Our laboratory is situated on the 2nd and 3rd floors of Building 6 (former Biochemistry building) of HPI, which their construction has been funded exclusively by the lab’s budget.
Our main activities include:
- The study of the structure and function of nicotinic acetylcholine receptors (nAChRs) which are implicated in several severe neurological diseases and disorders.
- The study of myasthenia gravis (MG), which is usually caused by anti-AChR autoantibodies, and the development of a specific therapy for this disease.
- The identification and characterization of novel MG subgroups with autoAbs against novel (like LRP4) or classical autoantigens
- The identification of a novel autoantigen in neuromyelitis optica (NMO) and characterization of the corresponding NMO subtype.
- The development of sensitive immunochemical diagnosis for three autoimmune neurological diseases (MG, NMO and LEMS).
- Services to the scientific community (e.g. monoclonal antibodies, mass production of recombinant proteins by a high-tech bioreactor, protein crystallization by a robot, DLS, etc) and support to the Greek MG Association.
The expansion of our lab on the two new floors includes, amongst others, a dedicated place (clean room) for the development of immunoadsorption columns under GMP standards necessary for the clinical trials for MG therapy, a crystallization room for structural studies, electrophysiology facility for recordings in Xenopus oocytes (Two-Electrode-Voltage-Clamp), appropriate culture rooms for the further development of improved diagnostics for neurological diseases and for the research on these diseases. Additionally, the expanded laboratory accommodates the administrative activities of the Hellenic Myasthenia Gravis Association (H-MGA). Furthermore, our group runs another electrophysiology facility for recordings in mammalian cell lines (patch clamp) situated on the ground floor of Building 6.
Nicotinic Acetylcholine Receptors (nAChRs)
Our laboratory is mainly studying the structure of the human nAChRs and their role in several related neurological diseases. nAChRs are the prototypic members of the pentameric ligand-gated ion channels (pLGICs) family, also including the serotonin 5-HT3, GABAA/C glycine and some invertebrate receptors. They form cation-selective channels of homologous subunits, each comprising an N-terminal extracellular domain (ECD) of 210-250 amino acids, bearing the acetylcholine (ACh) or ligand-binding sites, a transmembrane domain of four α-helices, a large cytoplasmic loop (110–270 amino acids). nAChRs are classified into muscle and neuronal receptors. The muscle nAChR forms heteropentamers with subunit stoichiometry of (α1)2β1γ(or ε)δ οn postsynaptic membranes of the neuromuscular junction, mediating neurotransmission for muscle contraction. It is the main autoantigen in the autoimmune disease myasthenia gravis (MG), while its mutations cause congenital myasthenic syndromes. The neuronal nAChRs are widely distributed in the peripheral and central nervous systems, regulating neuronal excitability and neurotransmitter release, and are also found in the immune system and in various peripheral tissues. To date, eleven neuronal nAChR subunits have been characterized in humans (α2-α7, α9, α10, β2-β4), forming either homopentamers (α7 or α9 pentamers) or heteropentamers of various combinations (e.g. α4β2, α7β2, α9α10), with each subtype presenting distinct pharmacological and electrophysiological properties. In all nAChRs, the acetylcholine (ACh)-binding sites are formed between the ECDs of an α subunit and an adjacent α or non-α subunit, conferring the principal (+) and the complementary (-) sides of the binding sites, respectively. Neuronal nAChRs are responsible for substances addiction (eg nicotine), while their dysfunction is related to various neurological and neuropsychiatric diseases, such as Alzheimer’s and Parkinson’s, autism, schizophrenia, epilepsy, depression, anxiety and attention deficit hyperactivity disorder. They are also implicated in the neuropathic chronic pain, inflammation, lung and breast cancers, and in some autoimmune disorders.
Muscle nAChR and MG
The skeletal muscle nAChR is fundamental for the neuromuscular transmission. In MG, patients produce autoantibodies, which destroy the AChRs at the neuromuscular junctions, resulting in muscular weakness and fatigability. As the number of diagnosed patients increases, there is a need for the development of improved and specific therapeutic approaches for MG. Our studies involve mainly a) the thorough understanding of the antigenic structure of muscle AChR, b) the pathogenic mechanisms in MG, c) efforts to develop novel immunospecific therapeutic approaches and d) the better diagnosis of the disease. The therapeutic approach which is being developed by our lab focuses on the use of recombinant nAChR fragments with near-native conformation as immunoadsorbents of patients’ antibodies (details concerning our results are presented in the “Research Programs” tab).
Neuronal nAChRs and drug design
Neuronal nAChRs are widely distributed in the peripheral and central nervous systems, regulating neuronal excitability and neurotransmitter release, and are also found in the immune system and in various peripheral tissues. Their dysfunction is related to various neurological and neuropsychiatric diseases. We have initiated studies on some of the most important subunits for understanding their structure, function and involvement in pathology with the ultimate aim to facilitate the design of effective and specific drugs targeting distinct subtypes associated with the above diseases. To this aim we express the ECDs of human neuronal nAChR subunits, as well as the intact and “truncated” nAChRs in higher eukaryotic expression systems, we produce monoclonal antibodies against them and we study their a) structural, b) pharmacological and c) electrophysiological properties (details concerning our results are presented in the “Research Programs” tab).
Aquaporin-1 and neuromyelitis optica (NMO)
NMO is a chronic inflammatory demyelinating disease of the CNS, related to multiple sclerosis (MS) and often misdiagnosed as MS. Abs to aquaporin-4 (AQP4), a water channel in the astrocytes, are detected in only ~50-70% of NMO patients, being an invaluable biomarker for NMO diagnosis. Yet, diagnosis of seronegative NMO remains challenging. We found that many “seronegative” NMO patients have Abs against aquaporin-1 (AQP1), another water channel of the astrocytes.
Hellenic Myasthenia Gravis Association (H-MGA)
We offered strong support to the MG patients of Greece for the creation and development of their Association (H-MGA; http://www.myasthenia.gr/), whose offices are hosted in our laboratory. The association aims at the assistance of the patients in every level.
Services to the scientific community
We provide many monoclonal antibodies against AChR subunits and several AChR subunit domains as well as MuSK and aquaporin-4 proteins, and we also provide the expertise for the production of monoclonal antibodies to important proteins, the mass production of recombinant proteins by a high-tech bioreactor, protein crystallization by a robotic system, DLS, electrophysiology, etc.
1. Tzartos, S.J., Tzartos, J., Stergiou Ch., Kilintireas, K. (2011). Biomarker. Greek patent no. 1007816 (17/102011), PCT/IB2012/054142
2.Tzartos, S.J., Trakas, N., Tzartos, J., Stergiou Ch., Zisimopoulou, P. (2010). Diagnostic Assays. Greek patent no. 1007341 (21/4/2010).
3. Tzartos, S.J., Psaridi-Linardaki, L., Kostelidou, K. and Mamalaki, A., (2003). Production of recombinant fragments of muscle AChR and their use for ex vivo immunoadsorption of anti-AChR antibodies from MG. Greek (nο. 1004240/2003) and European patent (no. 1509605/2009).
Head of the lab: Professor Socrates J. Tzartos
Tel: +30 210 6478844, Fax: +30 210 6478842
Nikos Trakas, firstname.lastname@example.org
Post-Doctoral Research Fellows:
Petros Giastas, email@example.com
Konstantinos Lazaridis, firstname.lastname@example.org
Christos Stergiou, email@example.com
John Tzartos, firstname.lastname@example.org
Paraskevi Zisimopoulou, email@example.com
Marios Zouridakis, firstname.lastname@example.org
Dafni Chroni, email@example.com
Eleftherios Zarkadas, firstname.lastname@example.org
Past members of the lab (2000-2016)
V. Avramopoulou, M. Belimezi, A. Bentenidi, K. Bitzopoulou, P. Evangelakou, E. Fostieri, I. Gavra, L. Jacobson, A. Karagiorgou, V. Katsemi, M. Kontou, K. Kostelidou, N. Kouvatsos, O. Lazos, A. Mamalaki, M. Marinou, E. Matsigkou, E. Papadaki, D. Papanastasiou, K. Poulas, E. Protopapadaki, L. Psaridi-Linardaki, M. Remoundos, L. Skriapa, A. Sotiriadis, P. Tsantili, A. Tsonis, Th. Tsouloufis.
Collaborating Laboratory in the Department of Pharmacy , University of Patras:
Associate Professor Konstantinos Poulas, email@example.com
Associate Professor George Patrinos, firstname.lastname@example.org
Current and past grants:
- Stavros Niarchos Foundation. Development of innovative biological products and services for infectious and neurodegenerative diseases: “Structural and functional studies of nAChRs” (2016-2019)
- Toleranzia. Treatment of experimental autoimmune MG (2016-2017)
- Hellenic Neuroimmunology Society. Antibodies to Aquaporin-1 in neuromyelitis optica (2016-2017)
- Muscular Dystrophy Association of America. Diagnosis and characterization of LRP4-MG, a novel myasthenia gravis subtype (2013-2016)
- GSRT Greek-Israeli bilateral Program: Development of tools for the understanding and diagnosis of neurological diseases (2013-2015)
- GSRT-Program Thalis: “Autoimmunity” (University of Patras, coordinator S. Tzartos) in collaboration with Prof. A. Tzioufa (University of Athens) and Prof. A. Germeni (University of Thessaly) 2012-2015
- GSRT-Program Excellence: Myasthenia Gravis (2012-2015)
- Association Francaises des Myopathies (AFM) Diagnosis, prevalence and characterization of a novel myasthenia gravis subtype, LRP4-MG (2012-2014)
- FP7-Regpot “Neurosign”. Development of a center of excellence in Neurosignaling. With the labs of R. Matsas and L. Probert (coordinator: S. Tzartos) 2010-2014
- FP7 Fight-MG. Myasthenias, a group of immune mediated neurolog. diseases (2009-2014)
- Muscular Dystrophy Association of America (MDA). Antigen-specific therapeutic autoantibody depletion in myasthenia gravis (MDA158763) 2010-2012
- FP7 Fight-MG. Myasthenias, a group of immune mediated neurological diseases: from etiology to therapy (2009-2013)
- FP7-Neurocypres. Neurotransmitter Cys-loop receptors: structure, function and disease (2008-2012)
- Association Francaises des Myopathies (AFM), Pentameric AChR extracellular domain for efficient autoantibody depletion in myasthenia gravis (2009-2011)
- FP6-STREP-Myastaid. Development of models to improve management of myasthenia gravis: From basic knowledge to clinical application (2006-2010)
- FP6- Public Health. European Myasthenia Gravis Network (EuroMyasthenia) 2006-2009
A. STRUCTURE AND FUNCTION OF NICOTINIC ACETYLCHOLINE RECEPTOR (nAChR)
Aim: To understand the structure–function relationships of the muscle and neuronal nAChRs with the ultimate aim to elucidate their pathogenic mechanisms, develop novel therapies and facilitate the design of efficient and subtype-specific drugs towards numerous associated neurological and neurodegenerative diseases.
We are expressing the extracellular domains (ECDs) of human muscle and neuronal nAChRs, as well as intact nAChRs, and we are studying their structure and their interaction with specific ligands and antibodies, as well as their pharmacological and electrophysiological properties. Specifically, we perform:
1. Expression of the ECDs of all the subunits of human neuronal nAChRs (α2-α7, α9, α10 and β2-β4) and of the subunits of human muscle nAChR (α1, β1, γ, δ) and expression of concatameric combinations of ECDs in eukaryotic expression systems.
2. Expression in higher eukaryotic systems (insect and mammalian cells) of intact and truncated nAChRs with the latter lacking their flexible cytoplasmic domains, so as to facilitate their structural studies.
3. Design and construction of mutated forms of nAChR subunits with improved structural and functional properties.
4. Mass production and purification of the recombinant proteins.
5. Production of monoclonal antibodies against these molecules.
6. Crystallization of nAChR-ECDs and truncated nAChRs in the absence and/or presence of characteristic ligands and elucidation of their X-ray crystal structures. This part was initiated in collaboration with the group of the late Nikos Oikonomakos, NHRF, Athens, an eminent crystallographer and excellent personality.
7. Electrophysiology experiments using Xenopus oocytes and/or mammalian cell lines expressing specific neuronal nAChRs bearing structure-guided mutations
We ultimately aim to map in detail the receptor ligand binding sites (such as for acetylcholine, nicotine, etc) through the analysis of receptor-ligand complexes, which will eventually lead to the rational design of novel pharmaceuticals against neurological diseases and disorders.
Major results of the Structure/Function arm of the group:
We recently elucidated the X-ray crystal structures of the ECDs of human neuronal α9 and α2 nAChR subunits, being the first structures reported for any neuronal nAChR by that time.
1. The α9-ECD structure was determined in its free state and in complexes with two antagonists (Fig. 1) at resolutions of 1.7 to 2.7 Å (Zouridakis et al 2014, Nature Struct & Mol Biol). α9 forms either homopentameric α9 or heteropentameric α9α10 nAChRs, both found in the inner ear, sympathetic neurons and non-neuronal cells. The α9-containing nAChRs are potential targets for the therapy of ear disorders, chronic pain, pemphigus vulgaris and lung and breast cancers. Our structures revealed i) an important interaction, involving the unique in α9 Thr147 residue, essential for the initial rearrangements triggered upon agonist binding, leading to channel opening, ii) a hydration pocket linking residues important for signal transmission, iii) a membrane-facing network coordinated by Arg210, coupling agonist binding to channel opening and iv) the interactions of antagonists with α9 and the rearrangements occurring upon their binding.
Fig. 1. Structures of the free and antagonist-bound human nAChR α9-ECD. Side-views of (a) the α9-ECD monomer, (b) the methyllycaconitine (MLA)-bound α9-ECD (MLA: displayed electron density in green mesh) and (c) the complex of α9-ECD (green) with α-bungarotoxin (magenta).
2. The α2-ECD structure was determined in its pentameric assembly induced by the bound agonist epibatidine (Fig. 2a,b), being the first reported pentameric structure for any neuronal nAChR domain (Kouvatsos et al 2016, PNAS) . α2 assembles with the β2 subunit to form α2β2 nAChRs whose dysfunction has been associated with nicotine dependence, asthma, bipolar disorder, obesity, and other conditions. Two α2β2 subtypes exist with either low or high agonist sensitivity (LS or HS, respectively) presumed to have stoichiometries (α2)3(β2)2 and (α2)2(β2)3, respectively. The α2-ECD structure revealed i) an interacting network with binding-site residues shaping the binding cavity and ii) critical residues that stabilize agonist binding. In addition, by structure-guided mutations and electrophysiology (Fig. 2c,d) we a) proved the existence of the α2/α2 binding site in the LS subtype and b) showed the importance of subunit interactions in mediating the signal transduction processes.
Overall, the elucidation of the 3D structures of α9 and α2 ECDs, are expected to serve as good templates for the modelling of other neuronal nAChR α-ECDs and as an aid for rational drug design to treat related diseases. Notably, as α2 and α4 subunits share 78% identity, the α2 structure will facilitate studies on the α4β2 nAChRs, which are of the highest pharmacological importance among nAChRs.
Fig. 2. Structure/function of α2β2 nAChR. (a-b) Side-view (a) and top-view (b) of the nAChR α2-ECD in complex with epibatidine. Each subunit is colored differently and the five epibatidine molecules are shown in orange spheres. (c-d) Electrophysiological responses to ACh of (d) the LS and (e) the HS subtype of α2β2 nAChR in transfected Xenopus oocytes.
B. UNDERSTANDING MYASTHENIA GRAVIS (MG)
Aim: To study the mode of action of the pathogenic MG autoantibodies and the development of antigen-specific therapies for MG.
As described in the introduction, myasthenia gravis (MG) is caused by autoantibodies against the AChR (usually) or MuSK (occasionally), both located at the post-synaptic membrane of the neuromuscular junction.
1. Animal models of AChR and MuSK MG
We developed animal models for both AChR-MG and MuSK-MG, based on the active immunization of rats with recombinant human AChR or MuSK ECDs. These models are invaluable tools in the study of MG, for understanding the pathogenic mechanisms involved, but also importantly for the in vivo testing of novel therapies.
2. Antigen-specific therapeutic removal of pathogenic antibodies
We aim at the selective removal of the anti-AChR and anti-MuSK autoantibodies from the blood of MG patients by the use of columns carrying extracellular domains of muscle AChR subunits or MuSK, capable of selectively binding these antibodies. Prerequisite for this aim is the heterologous expression of large quantities of these protein domains with a native conformation appropriate for binding the corresponding autoantibodies. Specifically, we perform:
- Heterologous expression of the ECDs of all five muscle nAChR subunits and of MuSK in eukaryotic expression systems (yeast Pichia pastoris and insect cells)
- Construction of mutant forms of these recombinant proteins with improved antigenic characteristics.
- Large-scale production and purification of the recombinant proteins. Preparation of immunoaffinity columns on sepharose beads.
- In vitro studies: testing the ability of the immunoaffinity columns to safely and efficiently adsorb the anti-AChR and anti-MuSK antibodies from large volumes of MG plasma or blood.
- Animal studies: Application of the immunoadsorption in the aforementioned experimental animal models.
- Design of future application of the immunoadsorption in clinical trials.
This effort is already at an advanced preclinical stage, it has lead to several publications and to a patent, and we hope to be able to initiate clinical trials before long.
3. Investigation of the functional mechanisms of autoantibodies in MG and search for responsible genetic factors
Autoantibodies against the AChR or MuSK are isolated from MG patients’ sera, as well as other serum components with potentially pathogenic or protective function, and their role is studied in cell culture and animal models.
Additionally, we are screening patients’ blood for single nucleotide polymorphisms (SNPs) in genes involved in the regulation of the immune response, which may be linked to predisposition of developing MG (in collaboration with Ass. Prof. G. Patrinos, Department of Pharmacy, University of Patras).
C. IDENTIFICATION OF A NOVEL AUTOANTIGEN IN NEUROMYELITIS OPTICA (NMO)
Taking advantage of our experience with MG, we have more recently initiated the study of another neurological autoimmune disease, neuromyelitis optica (NMO), or Davic’s disease. NMO is a chronic inflammatory demyelinating disease of the CNS, related to multiple sclerosis (MS) and often misdiagnosed as MS. However, NMO requires very different treatments from MS, while its wrong diagnosis leads to ineffective treatment, often with detrimental outcome. Abs to aquaporin-4 (AQP4), a water channel in CNS astrocytes, are an invaluable biomarker for NMO diagnosis. Yet, AQP4 Abs are detected in only ~50-70% of NMO patients while a small NMO subgroup has Abs against myelin oligodendrocyte glycoprotein (MOG). Diagnosis of seronegative NMO remains challenging. We found that many “seronegative” NMO patients have Abs against aquaporin-1 (AQP1), another water channel of the astrocytes. We initially developed specific RIAs by which we detected AQP1- and AQP4-autoAbs in 16.7% and 12%, respectively, of 348 patients suspected for NMO but not in controls. Anti-AQP1 specificity was confirmed by competition, protein immunoblotting and ELISA assays, whereas epitope localization was studied by immunoadsorption on intact cells expressing AQP1 and peptide mapping experiments. Most AQP1-Abs were of the complement-activating IgG1 subclass and the majority bound to the extracellular domain ECD of AQP1, suggesting a possible pathogenic role. Overall, AQP1-Abs may prove a novel biomarker for NMO probably with milder symptoms. Interestingly, in collaboration with E. Tuzun and H. Lassmann, we observed AQP1 (but not AQP4) loss in the brain demyelinating lesions of an AQP1-NMO patient, strongly suggesting a possible pathogenic role of these Abs
D. DEVELOPMENT OF ULTRA-SENSITIVE DIAGNOSIS FOR AUTOIMMUNE NEUROLOGICAL DISEASES
In addition to the routine tests, which are already used in our lab to diagnose three neurological diseases, MG, NMO and LEMS (i.e. detections of autoantibodies against AChR, MuSK, titin, aquaporin-4 and calcium channels), we are developing much more sensitive, than the currently available, techniques for the detection of very small quantities of the pathogenic antibodies against these antigens in order to reduce the chances for false negative diagnoses. We are already applying the ultra-sensitive technique for the routine diagnosis of anti-aquaporin-4 antibodies and we are working on the establishment of similar techniques for the anti-AChR and anti-MuSK antibodies.
We collaborate with several established international scientists in the fields of molecular and structural biology, biophysics and immunology. We also collaborate with many neurologists who provide invaluable biological material from well characterized patients. These collaborators are in major institutions and hospitals in >14 European countries, in USA, Israel, Turkey, China and Japan. Some of the international and local collaborators are:
- Dr. S. Berrih-Aknin (University P. and M. Curie, Paris): Neuroimmunology
- Dr. P. Bregestovski (Universite de Marseille): Electrophysiology
- Dr. P. Christadoss (University of Texas, USA): MG
- Dr. P.J. Corringer (Institut Pasteur Paris): Structural & Functional Biology
- Dr. M. DeBaets (Univ. Limburg, Maastricht, The Netherlands): Neuroimmunology
- Dr. S. Fuchs (Weizmann Institute of Science, Rehovot): Neuroimmunology.
- Dr. S. Labeit (Univ. Heidelberg, Germany): Muscle proteins (titin) in MG
- Dr. R. Mantegazza (Istituto “Carlo Besta”, Milan): Molecular Neurology
- Dr. A. Marx (Pathologisches Institut, Universitat Wurzburg, Germany): Cell Biology
- Dr. U. Maskos (Institut Pasteur Paris): Cell biology
- Dr. M. McIntosh (Univ. Utah, USA): Protein structure-function
- Dr. L. Mei (Georgia Health Sciences Univ. USA): Cell Biology
- Dr. M. Skok (Palladin Institute. Biochemistry, Kiev, Ukraine): Physiology
- Dr. V. Tsetlin (Shemyakin-Ovchinnikov Inst. of Bioorganic Chem., Moscow): Biophysics
- Dr. N. Unwin (Univ. of Cambridge): Structural Biology
- Dr. I. Grapsas (Aretaieion Hospital, Univ. of Athens): Plasmapheresis/Ab-apheresis
- Dr. E. Eliopoulos (Agricultural Univ of Athens): Structural Biology
- Dr. V. Zouvelou (Aeginition Hospital, Univ. of Athens): Neurology – Neuroimmunology
- Dr. C. Kilindireas (Aeginition Hospital, Univ. of Athens): Neurology – Neuroimmunology
- Dr. K. Poulas (University of Patras): Cessation of Smoking studies
- Dr. G. Patrinos (University of Patras): Identification of novel polymorphisms in nAChR genes
- Toleranzia (Sweden): MG animal models
- Glycorex Transplantation (Lund, Sweden): MG therapy by immunoadsorption
- Tzartos NeuroDiagnostics (Athens): Provides many sera/CSF for several neuroimmune diseases
- MedProt (Athens): our start-up spin-off: Development of diagnostic kits etc. The main aim of Medprot is to contribute to the sustainability of our research group
Lykhmus O, Koval L, Pastuhova D, Zouridakis M, Tzartos S, Komisarenko S, Skok M. The role of carbohydrate component of recombinant α7 nicotinic acetylcholine receptor extracellular domain in its immunogenicity and functional effects of resulting antibodies. 2016 Immunobiology;221(12):1355-1361. doi: 10.1016/j.imbio.2016.07.012.
Kouvatsos N, Giastas P, Chroni-Tzartou D, Poulopoulou C, TzartosSJ. Crystal structure of a human neuronal nAChR extracellular domain in pentameric assembly: Ligand-bound α2 homopentamer. Proc Natl Acad Sci U S A. 2016 Aug 23;113(34):9635-40. doi: 10.1073/pnas.1602619113.
Gilhus NE, Skeie GO, Romi F, Lazaridis K, Zisimoupoulou P, and Tzartos S. Myasthenia gravis-autoantibody characteristics and their implications for therapy. Nat. Rev. Neurol. 2016; 12(5):259-68. doi: 10.1038/nrneurol.2016.44. Epub 2016 Apr 22. Review
Küçükerden M, Huda R, Tüzün E, Yılmaz A, Skriapa L, Trakas N, T. Strait R, Finkelman FD, Kabadayı S, Zisimopoulou P, TzartosS, Christadoss P. MuSK induced experimental autoimmune myasthenia gravis does not require IgG1 antibody to MuSK. J. Neuroimmunol. 2016. Jun 15;295-296:84-92. doi: 10.1016/j.jneuroim.2016.04.003.
Stergiou C, Lazaridis K, Zouvelou V, Tzartos J, Mantegazza R, Antozzi C, Andreetta F, Evoli A, Deymeer F, Saruhan-Direskeneli G, Durmus H, Brenner T, Vaknin A, Berrih-Aknin S, Behin A, Sharshar T, De Baets M, Losen M, Martinez-Martinez P, Kleopa KA, Zamba-Papanicolaou E, Kyriakides T, Kostera-Pruszczyk A, Szczudlik P, Szyluk B, Lavrnic D, Basta I, Peric S, Tallaksen C, Maniaol A, Gilhus NE, Casasnovas Pons C, Pitha J, Jakubíkova M, Hanisch F, Bogomolovas J, Labeit D, Labeit S, TzartosSJ.Titin antibodies in “seronegative” myasthenia gravis – A new role for an old antigen, J. Neuroimmunology, 2016. 292: 108-115. doi: 10.1016/j.jneuroim.2016.01.018.
Lykhmus O, Voytenko L, Koval L, Mykhalskiy S, Cholin V, Peschana K, Zouridakis M, Tzartos S, Komisarenko S and Skok M. α7 Nicotinic Acetylcholine Receptor-Specific Antibody Induces Inflammation And Amyloid β42 Accumulation In The Mouse Brain To Impair Memory. Plos-1, 2015 Mar 27;10(3):e0122706. doi: 10.1371/journal.pone.0122706.
Maurer M, Bougoin S, Feferman T, Frenkian M, Bismuth J, Mouly V, Clairac G, Tzartos S, Fadel E, Eymard B, Fuchs S, Souroujon MC, Berrih-Aknin S. IL-6 and Akt are involved in muscular pathogenesis in myasthenia gravis. Acta Neuropathol Commun. 2015 Jan 15;3(1):1. doi: 10.1186/s40478-014-0179-6.
Azam L, Papakyriakou A, Zouridakis M, Giastas P, Tzartos SJ, McIntosh JM. Molecular Interaction of α-Conotoxin RgIA with the Rat α9α10 Nicotinic Acetylcholine Receptor.Mol Pharmacol. 2015 May;87(5):855-64. doi: 10.1124/mol.114.096511. Epub 2015 Mar 4. PMID:25740413
Arnaouteli S, Giastas P, Andreou A, Tzanodaskalaki M, Aldridge C, Tzartos SJ, Vollmer W, Eliopoulos E, Bouriotis V. Two putative polysaccharide deacetylases are required for osmotic stability and cell shape maintenance in Bacillus anthracis. J Biol Chem. 2015 Mar 30.pii: jbc.M115.640029. [Epub ahead of print] PMID:25825488
Yilmaz V, Oflazer P, Aysa F, Durmus H, Poulas K, Parman Y, Tzartos S, Tuzun E, Deymeer F, Saruhan-Direskeneli G. Differential cytokine changes in patients with myasthenia gravis with antibodies against AChR and MuSK. PLOS-1. 2015; 10(4):e0123546. doi: 10.1371/journal.pone.0123546
Özkök E, Durmus H, Yetimler B, Taslı H, Trakas N, Ulusoy C, Lagoumintzis G, Tzartos S, and Tüzün E: Reduced muscle mitochondrial enzyme activity in MuSK-immunized mice. Clinical Neuropathology. 2015 Nov-Dec;34(6):359-63. doi: 10.5414/NP300875.
Ulusoy C, Zibandeh N, Yıldırım S, Trakas N, Zisimopoulou P, Küçükerden M, Tașlı H, TzartosS, Göker K, Tüzün E, Akkoç T. Dental follicle mesenchymal stem cell administration ameliorates muscle weakness in MuSK-immunized mice. J Neuroinflammation. 2015 Dec 9;12(1):231. doi: 10.1186/s12974-015-0451-0.
Tsonis AI, Zisimopoulou P, Lazaridis K, Tzartos J, Matsigkou E, Zouvelou V, Mantegazza R, Antozzi C, Andreetta F, Evoli A, Deymeer F, Saruhan-Direskeneli G, Durmus H, Brenner T, Vaknin A, Berrih-Aknin S, Behin A, Sharshar T, De Baets M, Losen M, Martinez-Martinez P, Kleopa KA, Zamba-Papanicolaou E, Kyriakides T, Kostera-Pruszczyk A, Szczudlik P, Szyluk B, Lavrnic D, Basta I, Peric S, Tallaksen C, Maniaol A, Casasnovas Pons C, Pitha J, Jakubíkova M, Hanisch F, TzartosSJ. MuSK autoantibodies in myastheniagravis detected by cell based assay-A multinational study. J Neuroimmunol. 2015 Jul 15;284:10-7. doi: 10.1016/j.jneuroim.2015.04.015.
Lykhmus O, Gergalova G, Zouridakis M, Tzartos S, Komisarenko S, Skok M. Inflammation decreases the level of alpha7 nicotinic acetylcholine receptors in the brain mitochondria and makes them more susceptible to apoptosis induction. Int Immunopharmacol. 2015 Nov;29(1):148-51. doi: 10.1016/j.intimp.2015.04.007. Epub 2015 Apr 15.
Tuzun E, Berrih-Aknin S, Brenner T, Kusner LL, Le Panse R, Yang H, Tzartos S, Christadoss P. Guidelines for standard preclinical experiments in the mouse model of myasthenia gravis induced by acetylcholine receptor immunization. Exp Neurol. 2015 Feb 16. pii: S0014-4886(15)00032-1. doi: 10.1016/j.expneurol.2015.02.009. [Epub ahead of print]. PMID:25697844
Kusner LL, Losen M, Vincent A, Lindstrom J, Tzartos S, Lazaridis K, Martinez-Martinez P. Guidelines for pre-clinical assessment of the acetylcholine receptor-specific passive transfer myasthenia gravis model-Recommendations for methods and experimental designs. Exp Neurol. 2015 Mar 3.pii: S0014-4886(15)00055-2. doi: 10.1016/j.expneurol.2015.02.025. [Epub ahead of print] PMID:25743217
Losen M, Martinez-Martinez P, Molenaar PC, Lazaridis K, Tzartos S, Brenner T, Duan RS, Luo J, Lindstrom J, Kusner L. Standardization of the experimental autoimmune myasthenia gravis (EAMG) model by immunization of rats with Torpedo californica acetylcholine receptors – Recommendations for methods and experimental designs. Exp Neurol. 2015 Mar 18.pii: S0014-4886(15)00078-3. doi: 10.1016/j.expneurol.2015.03.010. [Epub ahead of print] PMID:25796590.
Zouvelou V, Zisimopoulou P, Psimenou E, Matsigkou E, Stamboulis E, Tzartos SJ. AChR-myasthenia gravis switching to double-seropositive several years after the onset.J. Neuroimmunol. 2014 Feb 15;267(1-2):111-2. doi: 10.1016/j.jneuroim.2013.12.012.
Tsivgoulis G, Dervenoulas G, Tzartos SJ, Zompola C, Papageorgiou SG, Voumvourakis K. Double seropositive myasthenia gravis with acetylocholine receptor and lipoprotein receptor-related protein 4 antibodies. Muscle and Nerve.2014 Jan 7.doi: 10.1002/mus.24166. [Epub ahead of print]
Zis P, Argiriadou V, Temperikidis PP, Zikou L, Tzartos SJ, Tavernarakis A. Parkinson’s disease associated with myasthenia gravis and rheumatoid arthritis. Neurol. Sci.(Letter to the Editor). Published on line 2-7-2014. DOI 10.1007/s10072-014-1660-5
Marino M, Maiuri MT, Di Sante G, Scuderi F, La Carpia F, Trakas N, Provenzano C, Zisimopoulou P, Ria F, Tzartos SJ, Evoli A, Bartoccioni E. T cell repertoire in DQ5-positive MuSK-positive myasthenia gravis patients. J Autoimmun. 2014 Jan 4.pii: S0896-8411(13)00154-6. doi: 10.1016/j.jaut.2013.12.007. [Epub ahead of print]
Avidan N, Le Panse R; Harbo H, Bernasconi P, Poulas K, Ginzburg E; Cavalcante P, Colleoni L; Baggi F, Antozzi C, Truffault F, Horn-Saban S, Pöschel S, Zagoriti Z, Maniaol A, Lie B; Bernard I, Saoudi A, Illes Z, Casasnovas C, Melms A, Tzartos S; Willcox N, Kostera-Pruszczyk A, Tallaksen C, Mantegazza R, Berrih-Aknin S, Miller A. VAV1 and BAFF, via NFκB pathway, are genetic risk factors for Myasthenia Gravis. 2014 Annals of Clinical and Translational Neurology,1(5):329-39. doi: 10.1002/acn3.51
Ulusoy C, Kim E, Tüzün E, Huda R, Yılmaz V, Poulas K, Trakas N, Skriapa L, Niarchos A, Strait RT, Finkelman FD, Turan S, Zisimopoulou P, Tzartos S, Saruhan-Direskeneli G, Christadoss P. Preferential production of IgG1, IL-4 and IL-10 in MuSK-immunized mice. Clin Immunol. 2014 Feb 28.pii: S1521-6616(14)00049-7. doi: 10.1016/j.clim.2014.02.012. [Epub ahead of print].
Tuzun E., Tzartos J., Ekizoglu E., Stergiou C., Zisimopoulou P., Çoban A., Shugaiv E., Türkoglu R., Kürtüncü M., Baykan B., Tzartos S. Title: Aquaporin-1 Antibody in Neuromyelitis Optica Patients. European Neurology, 2014. Eur Neurol. 2014 Sep 27;72(5-6):271-272. [Epub ahead of print].
Kouvatsos N, Niarchos A, Zisimopoulou P, Eliopoulos E, Poulas K, and Tzartos S. Purification and functional characterization of a truncated human α4β2 nicotinic acetylcholine receptor. Int. J Biol Macromol, 2014 Jul 8. pii: S0141-8130(14)00441-3. doi: 10.1016/j.ijbiomac.2014.06.058. [Epub ahead of print]
Boltsis I, Lagoumintzis G, Chatzileontiadou DSM, Giastas P, Tzartos SJ, Leonidas DD, and Poulas K. Non-contact Current Transfer Induces the Formation and Improves the X-ray Diffraction Quality of Protein Crystals. 2014 Cryst.Growth Des. DOI: 10.1021/cg5004098
Zouridakis M, Giastas P, Zarkadas E, Chroni-Tzartou D, Bregestovski P and Tzartos SJ. Crystal structures of the free and antagonist-bound states of the extracellular domain of human α9 nicotinic receptor. 2014. Nat. Struct & Mol. Biol. doi:10.1038/nsmb.2900.
Tsivgoulis G, Dervenoulas G, Kokotis P, Zompola C, Tzartos J, Tzartos SJ, Voumvourakis KI. Double seronegative myasthenia gravis with low density lipoprotein-4 (LRP4) antibodies presenting with isolated ocular symptoms. 2014. J. Neurol. Sci. doi: 10.1016/j.jns.2014.09.013.
Kordas G, Lagoumintzis G, Sideris S, Poulas K and Tzartos SJ.Direct proof of the in vivo pathogenic role of the AChR autoantibodies from myasthenia gravis patients.PLOS-1.2014. Sep 26;9(9):e108327. doi: 10.1371/journal.pone.0108327.
Skriapa L, Zisimopoulou P, Trakas N, Grapsa E, Tzartos SJ. Expression of extracellular domains of Muscle Spesific Kinase (MuSK) and use as immunoadsorbents for the development of an antigen specific therapy. 2014. J. Neuroimmunol. DOI: 10.1016/j.jneuroim.2014.09.013
Lazaridis K, Evaggelakou P, Bendenidi E, Sideri A, Grapsa E and Tzartos S.J. Specific adsorbents for myasthenia gravis autoantibodies using mutants of the muscle nicotinic acetylcholine receptor extracellular domains. J. Neuroimmunol. 2015 Jan 15;278:19-25. doi: 10.1016/j.jneuroim.2014.12.001. Epub 2014 Dec 3.
Zouvelou V, Stamboulis E, Skriapa L, Tzartos SJ. MuSK-Ab positive myasthenia: Not always grave. J Neurol Sci. 2013, 15;331(1-2):150-1.
Zouvelou V, Kyriazi S, Rentzos M, Belimezi M, Micheli MA, Tzartos SJ, Stamboulis E. Double-seropositive myasthenia gravis. Muscle Nerve. 2013, 47(3):465-6.
Zouvelou V, Zisimopoulou P, Rentzos M, Karandreas N, Evangelakou P, Stamboulis E, Tzartos SJ. Double seronegative myasthenia gravis with anti-LRP 4 antibodies.Neuromuscul Disord. 2013 Jul;23(7):568-70.
Tzartos JS, Stergiou Ch, Kilidireas K, Zisimopoulou P, Thomaidis T, and Tzartos SJ, Aquaporin-1 autoantibodies in patients with neuromyelitis optica spectrum disorders. PLOS-1, 2013.doi: 10.1371/journal.pone.0074773.
Lagoumintzis G, Zisimopoulou P, Trakas N, Grapsas E, Poulas K and Tzartos SJ (2013). Scale up and safety parameters of antigen specific immunoadsorption of human anti-acetylcholine receptor antibodies. J. Neuroimmunol. 2014; 267(1-2):1-6. doi: 10.1016/j.jneuroim. 2013.11.001. Epub 2013 Nov 10.
Zisimopoulou P, Evangelakou P, Tzartos J, Lazaridis K, Zouvelou V, Mantegazza R, Antozzi C, Andreetta F, Evoli A, Deymeer F, Saruhan-Direskeneli G, Durmus H, Brenner T, Vaknin A, Berrih-Aknin S, Frenkian Cuvelier M, Stojkovic T, Debaets M, Losen M, Martinez-Martinez P, Kleopa KA, Zamba-Papanicolaou E, Kyriakides T, Kostera-Pruszczyk A, Szczudlik P, Szyluk B, Lavrnic D, Basta I, Peric S, Tallaksen C, Maniaol A, & Tzartos SJ. A comprehensive analysis of the epidemiology and clinical characteristics of anti-LRP4 in myasthenia gravis. J. Autoimmunity. 2013. Epub ahead of print. http://dx.doi.org/10.1016/j.jaut.2013.12.004
Vrolix K, Fraussen J, Losen M, Stevens J, Lazaridis K, Molenaar PC, Somers V, Bracho MA, Le Panse R, Stinissen P, Berrih-Aknin S, Maessen JG, Van Garsse L, Buurman WA, Tzartos SJ, De Baets MH, Martinez-Martinez P. Clonal heterogeneity of thymic B cells from early-onset myasthenia gravis patients with antibodies against the acetylcholine receptor. J. Autoimmunity. 2014. doi: 10.1016/j.jaut.2013.12.008.
Lazaridis K, Zisimopoulou P, Giastas P, Bitzopoulou K, Evangelakou P; Sideri A, Tzartos SJ. Expression of human AChR extracellular domain mutants with improved characteristics. 2014 J Biol. Macromol;63:210-7. doi: 10.1016/j.ijbiomac.2013.11.003. Epub 2013 Nov 15
Niarchos A, Zouridakis M, Douris V, Georgostathi A, Kalamida D, Sotiriadis A, Poulas K, Iatrou K.. Tzartos SJ. Expression of a highly antigenic and native-like folded extracellular domain of the human α1 subunit of muscle nicotinic acetylcholine receptor, suitable for use in antigen specific therapies for Myasthenia Gravis. 2013 PLOS-1; 8(12):e84791. doi: 10.1371/journal.pone.0084791
Tzartos JS, Zisimopoulou P, Rentzos M, Karandreas N, Zouvelou V, Evangelakou P, Tsonis A, Thomaidis T, Lauria G, Andreetta F, Mantegazza R, Tzartos SJ. LRP4 antibodies in serum and CSF from amyotrophic lateral sclerosis patients. Ann. Clin Transl Neurol. Dec. 2013. doi: 10.1002/acn3.26.
Zisimopoulou P, Brenner T, Trakas N, Tzartos SJ. Serological diagnostics in myasthenia gravis based on novel assays and recently identified antigens. Autoimmun Rev. 2013 Jul;12(9):924-30.
Zagoriti Z, Kambouris M, Patrinos GP, Tzartos S, and Poulas K. (2013). Recent advances in genetic predisposition of myasthenia gravis. BioMed Res Int. Epub 2013 Nov 5.
Zagoriti Z, Georgitsi M, Giannakopoulou O, Ntellos F, Tzartos SJ, Patrinos GP, Poulas K. Genetics of myasthenia gravis: a case-control association study in the Hellenic population. Clin Dev Immunol. 2012;2012:484919. doi:10.1155/2012/484919. Epub 2012 Sep 25.
Poulas K, Koutsouraki E, Kordas G, Kokla A, Tzartos SJ. Anti-MuSK- and anti-AChR-positive myasthenia gravis induced by d-penicillamine. J Neuroimmunol. 2012 Sep 15;250(1-2):94-8. doi: 10.1016/j.jneuroim.2012.05.011.
Tzartos, J., C. Stergiou, H. Alexopoulos, P. Zisimopoulou, C. Karageorgiou, K. Kilintireas, M. Dalakas, and S. Tzartos, (2012) Highly Sensitive Radioimmunoassay Identifies Anti-Aquaporin-4 Autoantibodies in Several “Seronegative” Patients Suspected for Neuromyelitis Optica-Spectrum Disorders (NMO). Neurology, 78, P02133.
Zhang, B., J.S. Tzartos, M. Belimezi, S. Ragheb, B. Bealmear, R.A. Lewis, W.C. Xiong, R.P. Lisak, S.J. Tzartos, and L. Mei, (2012) Autoantibodies to Lipoprotein-Related Protein 4 in Patients With Double-Seronegative Myasthenia Gravis. Archives of Neurology. 69(4): p. 445-451.
Trakas, N., P. Zisimopoulou, and S.J. Tzartos, Development of a highly sensitive diagnostic assay for muscle-specific tyrosine kinase (MuSK) autoantibodies in myasthenia gravis. 2011 Journal of Neuroimmunology. 240: p. 79-86.
Koval, L., O. Lykhmus, O. Kalashnyk, N. Bachinskaya, G. Kravtsova, M. Soldatkina, M. Zouridakis, C. Stergiou, S. Tzartos, V. Tsetlin, S. Komisarenko, and M. Skok, (2011) The Presence and Origin of Autoantibodies Against alpha 4 and alpha 7 Nicotinic Acetylcholine Receptors in the Human Blood: Possible Relevance to Alzheimer’s Pathology. Journal of Alzheimers Disease. 25(4): p. 747-761.
Lykhmus, O., L. Koval, M. Skok, M. Zouridakis, P. Zisimopoulou, S. Tzartos, V. Tsetlin, S. Granon, J.P. Changeux, S. Komisarenko, and I. Cloez-Tayarani, (2011) Antibodies against Extracellular Domains of alpha4 and alpha7 Subunits Alter the Levels of Nicotinic Receptors in the Mouse Brain and Affect Memory: Possible Relevance to Alzheimer’s Pathology. Journal of Alzheimers Disease. 24(4): p. 693-704.
Pavlakis, P.P., H. Alexopoulos, M.L. Kosmidis, E. Stamboulis, J.G. Routsias, S.J. Tzartos, A.G. Tzioufas, H.M. Moutsopoulos, and M.C. Dalakas, (2011) Peripheral neuropathies in Sjogren syndrome: a new reappraisal. Journal of Neurology Neurosurgery and Psychiatry. 82(7): p. 798-802.
Stergiou, C., P. Zisimopoulou, and S.J. Tzartos, (2011) Expression of Water-soluble, Ligand-binding Concatameric Extracellular Domains of the Human Neuronal Nicotinic Receptor alpha 4 and beta 2 Subunits in the Yeast Pichia pastoris; glycosylation is not required for ligand binding. Journal of Biological Chemistry. 286(11): p. 8884-8892.
Keefe, D., C. Parng, D. Lundberg, S. Ray, J. Martineau-Bosco, C. Leng, S. Tzartos, J. Powell, M. Concino, M. Heartlein, J. Lamsa, and S. Josiah, (2010) In vitro characterization of an acetylcholine receptor-transferrin fusion protein for the treatment of myasthenia gravis. Autoimmunity. 43(8): p. 628-639.
Lagoumintzis, G., P. Zisimopoulou, G. Kordas, K. Lazaridis, K. Poulas, and S.J. Tzartos, (2010) Recent approaches to the development of antigen-specific immunotherapies for myasthenia gravis. Autoimmunity. 43(5-6): p. 436-445.
Gattenlohner, S., H. Jorissen, M. Huhn, A. Vincent, D. Beeson, S. Tzartos, A. Mamalaki, B. Etschmann, H.K. Muller-Hermelink, E. Koscielniak, S. Barth, and A. Marx, A Human Recombinant Autoantibody-Based Immunotoxin Specific for the Fetal Acetylcholine Receptor Inhibits Rhabdomyosarcoma Growth In Vitro and in a Murine Transplantation Model. Journal of Biomedicine and Biotechnology Art. No. 187621.
Keefe, D., Hess, D., Dosco, J., Tzartos, S., Powell, J., Lamsa. J., and Josiah, S. (2009) A rapid, fluorescence based assay for detecting antigenic modulation of the acetylcholine receptor on human cell lines. Cytometry B Clin Cytom. 76(3):206-12.
Zouridakis M, Zisimopoulou P, Eliopoulos E, Poulas K, and Tzartos SJ (2009) Design and expression of human α7 nicotinic acetylcholine receptor extracellular domain mutants with enhanced solubility and ligand-binding properties. Bioch. Bioph. Acta. 1794: 355-66.
Tsiamalos, P., Kordas, G., Kokla, A., Poulas, K., and Tzartos, S.J. (2009). Epidemiological and immunological profile of MuSK myasthenia gravis in Greece. Eur. J. Neurol. 16: 925-30.
Lykhmus, O , Koval, L., Pavlovych, S., Zouridakis, M., Zisimopoulou, P., Tzartos, S., Tsetlin, V., Volpina, O., Cloëz-Tayarani, I., Komisarenko, S., and Skok, M. (2009) Functional effects of antibodies against non-neuronal nicotinic acetylcholine receptors. Immunol. Lett. 128(1):68-73.
Gattenlohner, S, Jörißen, H., Huhn, M., Vincent, A., Beeson, D., Tzartos, S., Mamalaki, A., Etschmann, B., Müller-Hermelink, H.K., Koscielniak, E., Barth S.and Marx, A. (2009). A human recombinant autoantibody-based immunotoxin specific for the fetal acetylcholine receptor inhibits rhabdomyosarcoma growth in vitro and in a murine transplantation model. J. Biomed. Biotech. 2010:187621. doi: 10.1155/2010/187621
Keefe, D., Parng , C., Lundberg, D., Ray, S., Martineau-Bosc, J., Leng, C., Tzartos, S., Powell , J., Concino, M., Michael Heartlein, M., Lamsa. J., and Josiah, S. (2010). In vitro characterization of an acetylcholine receptor-transferrin fusion protein for the treatment of Myasthenia Gravis. Autoimmunity, 43(8):628-39
Konstantakaki, M, Tzartos, S.J., Poulas, K. and Eliopoulos, E. (2008). Μodel of the extracellular domain of the human α7 nAChR based on the crystal structure of the mouse α1 nAChR extracellular domain. J. Mol. Graph Modelling. 26: 1333-7.
Bitzopoulou, K., ,Kostelidou, K., Poulas, K and Tzartos, S.J. (2008) Expression and characterization of mutant forms of the extracellular domain of the human AChR gamma-subunit with improved solubility and enhanced antigenicity. Biochem. Biophys. Acta. 1784: 1226-33.
Zisimopoulou, P., Lagoumintzis, G., Poulas, K. and Tzartos, S.J. (2008). Antigen-specific apheresis of human anti-acetylcholine receptor autoantibodies from myasthenia gravis patients’ sera using Escherichia coli-expressed receptor domains. J. Neuroimmmunol. 200: 133-141.
Yi, H.J., Chae, C.S., So, J.S., Tzartos, S.J. Souroujon MC, Fuchs, S., Im, SH (2008) Suppression of experimental myasthenia gravis by a B-cell epitope-free recombinant acetylcholine receptor. Mol. Immunol. 461:192-201.
Konstantakaki, M., Tzartos, S.J., Poulas, K., and Eliopoulos, E. (2007) Molecular modeling of the complex between Torpedo acetylcholine receptor and anti-MIR Fab198. Biochem. Biophys. Res. Commun. 356:569-75.
Sideris, S., Lagoumintzis, G., Kordas, G., Kostelidou, K., Sotiriadis, A, Poulas, K. and Tzartos, S.J. (2007) Isolation and functional characterization of anti-acetylcholine receptor subunit-specific autoantibodies from myasthenic patients: receptor loss in cell culture. J. Neuroimmunol. 189:111-7.
Zouridakis, M., Kostelidou, K., Sotiriadis, A., Stergiou, Ch. Eliopoulos, E., Poulas, K., and Tzartos, S. (2007) Circular Dichroism Studies of Recombinant Extracellular Domains of Human Muscle and Neuronal Nicotinic Acetylcholine Receptors Provide an Insight into their structure. Intl. J. Biol. Macromol. 41:423-9.
Kostelidou, K., Trakas,N. and Tzartos, S.J. (2007) Extracellular domains of the β, γ and ε subunits of the human acetylcholine receptor as immunoadsorbents for myasthenic autoantibodies: a combination of immunoadsorbents results in increased efficiency. J. Neuroimmmunol. 190:44-52
Kostelidou, K., Trakas,N., Zouridakis, M., Bitzopoulou, K., Sotiriadis,A., Gavra, H., and Tzartos, S.J. (2006). Expression and characterization of soluble forms of the extracellular domains of the β, γ and ε subunits of the human muscle acetylcholine receptor. FEBS J. 273: 3557-3568
Fostieri, E., Tzartos, S.J., Berrih-Aknin, S., Beeson, D. and Mamalaki A. (2005) Isolation of potent human Fab fragments against a novel highly immunogenic region on human muscle acetylcholine receptor, which protect the receptor from myasthenic autoantibodies. Eur. J. Immunol. 35:632-643.
Protopapadakis, E., Kokla, A., Tzartos, S.J. and Mamalaki, A (2005) Isolation and characterization of human anti-acetylcholine receptor monoclonal antibodies from transgenic mice expressing human immunoglobulin loci. Eur. J. Immunol. 35:1960-68.
Guyon, S., Christadoss, P., Lepanse, R, Guyon, T, DePoea Baets, M., Wakkach, A., Bidault, J., Tzartos, S., and Berrih-Aknin, S. (2005) Effects of cytokines on AChR expression. Implications for myasthenia gravis. J. Immunol. 174: 5941-49.
Psaridi-Linardaki, L., Mamalaki, A., Trakas, N. and Tzartos, S.J. (2005) Specific immunoadsorption of the autoantibodies from myasthenic patients using the extracellular domain of the human muscle acetylcholine receptor α-subunit. Development of an antigen-specific therapeutic strategy. J. Neuroimmunol. 159:183-91.
Avramopoulou, V., Mamalaki, A., Tzartos, S.J. (2004) Soluble, oligomeric and ligand-binding extracellular domain of human alpha7 acetylcholine receptor expressed in yeast. Replacement of the hydrophobic cys-loop by the hydrophilic loop of ACh-binding protein enhances protein solubility. J. Biol. Chem. 279: 38287-93.
Marinou, M. and Tzartos, S.J. (2003). Identification of regions involved in the binding of α-Bungarotoxin to the human α7 neuronal nicotinic acetylcholine receptor using synthetic peptides. Biochem. J. 372, 543-554.
Phan-Chan-Du, A., Hemmerlin, C., Krikorian, D., Sakarellos-Daitsiotis, M., Tsikaris, V., Sakarellos, C., Marinou. M.,Thureau, A., Cung, M.T. and Tzartos, S.J. (2003). Solution conformation of the antibody-bound tyrosine phosphorylation site of the nicotinic acetylcholine -subunit in its phosphorylated and nonphosphorylated states. Biochemistry, 42:7371-7380.
Campos, E.C., Schiavi, C., Bolognesi, A., Bellusci, C., Lubelli, C., Duca, A., Polito, L., Vismara, S., Poulas, K., Tzartos, S.I., and Stirpe, F. (2002). Selective lesions of rabbit extraocular muscles injected with the anti-AChR immunotoxin saporin-mAb 73. Curr. Eye Res. 24: 58-65.
Psaridi-Linardaki, L.,Mamalaki, A., Remoundos, M. and Tzartos, S.J. (2002). Expression of soluble ligand- and antibody-binding extracellular subunit in yeast Pichiadomain of human muscle acetylcholine receptor α- pastoris. Role of glycosylation in α-bungarotoxin binding. J. Biol. Chem. 277: 26980-6.
Μetaxas, A., Tzartos, S., Liakopoulou-Kyriakide, M. (2002). The production of anti-hexapeptide antibodies which recognize the S7, L6 and L13 ribosomal proteins of Escherichia coli. J Pept Sci. 8:118-24.
Tataridis, D., Kolocouris, A., Fytas, G., Kolocouris, N., Foscolos, G.B., Poulas, K. and Tzartos, S.J. (2002).Mounting the nicotinic pharmacophoric structural elements in an homoadamantane scaffold: synthesis, molecular modeling and binding affinities to α7 nicotinic acetylcholine receptors. IL Farmaco. 57:979-984.
Poulas, K. and Tzartos, S.J (2001). The gender gap in autoimmune disease. Letter to Lancet, 357, 234.
Poulas, K., Eliopoulos, E., Vatzaki, E., Navaza, J., Kontou, M., Oikonomakos, N., Acharya, K.R., and Tzartos, S. J. (2001). Crystal structure of Fab198, an efficient protector of acetylcholine receptor against myasthenogenic antibodies. Eur. J. Biochem. 268: 3685-3693.
Poulas, K., Tsibri, E., Papanastasiou, D., Tsouloufis, T., Marinou, M., Tsantili, P., Papapetropoulos, T., and Tzartos, S.J. (2001). Epidemiology of seropositive myasthenia gravis in Greece. J. Neurol. Neurosur. Psych. 71:352-6.
Theodorou, V.,Tsikaris, V., Sakarellos-Daitsiotis, M, Avramopoulou, V., Kostelidou, K., Tzartos, S.J. and Sakarellos, C. (2001). Design, synthesis and conformational study of biologically active photolabeled analogues of the Main Immunogenic Region of the acetylcholine receptor. Biopolymers. 56: 37-46.
Trakas, N. and Tzartos, S.J. (2001) Conjugation of acetylcholine receptor-protecting Fab fragments with polyethylene glycol results in a prolonged half-life in the circulation and reduced immunogenicity. J. Neuroimmunol. 120:42-49.
Skok, M., Lykhmus, E., Bobrovnik, S., Tzartos, S.I., Tsouloufis, T., Vanderesse, R. , Coutrot, F., Cung, M.T., Marraud, M., Krikorian, D., and Sakarellos-Daitsiotis, M. (2001). Structure of epitopes recognized by the antibodies to alpha (181-192) peptides of neuronal nicotinic acetylcholine receptors: extrapolation to the structure of acetylcholine-binding domain. J. Neuroimmunol. 121: 59-66.
Kleinjung, J., Petit, M-C., Orlewski, P., Mamalaki, A., Tzartos, S.J., Tsikaris, V., Sakarellos-Daitsiotis, M., Sakarellos, C., Marraud, M. and Cung. M.-T. (2000). The 3D structure of the complex between an Fv antibody fragment and an analogue of the main immunogenic region of the acetylcholine receptor: A combined 2D-NMR, homology and molecular modeling approach. Biopolymers. 53: 113-128
Sevin-Landais, A., Rigler, P., Tzartos, S., Hucho, F., Hovius, R. and Vogel, H. (2000). Immobilisation of the nicotinic acetylcholine receptor in tethered lipid membranes. Biophys. Chem. 85:141-52.
Poulas, K., Tsouloufis, Th., and Tzartos S.J. (2000) Treatment of passively transferred experimental autoimmune myasthenia gravis using papain. Clin. Expl. Immunol. 120:363-368.
Tsouloufis, T., Mamalaki, A., Remoundos, M. and Tzartos, S.J. (2000). Reconstitution of conformationally-dependent epitopes on the N-terminal extracellular domain of the human muscle acetylcholine receptor α-subunit expressed in E. coli. Implications for Myasthenia Gravis therapeutic approaches. Int. Immunol. 12: 1255-65.
Papanastasiou, D., Poulas, K., Kokla, A and Tzartos, S. J. (2000). Prevention of passively transferred experimental autoimmune myasthenia gravis by Fab fragments of monoclonal antibodies directed against the main immunogenic region of the acetylcholine receptor. J. Neuroimmunol. 104:124-132.
Kontou, M., Leonidas, D., Vatzaki, E.H., Tsantili, P., Mamalaki, A., Oikonomakos, N.G., Acharya, K.R, and Tzartos, S. J. (2000).The crystal structure of the Fab fragment of a rat monoclonal antibody against the main immunogenic region of the human muscle acetylcholine receptor. Eur. J. Biochem. 267:2389-2397
Michalet, S., Teixeira, F., Gilquin, B., Mourier, G., Servent, S., Drevet, P., Binder, P., Tzartos, S., Ménez, A., and Kessler, P. (2000). Relative spatial position of a snake neurotoxin and the reduced disulfide bond αCys192-Cys193) at the αγ interface of the nicotinic acetylcholine receptor. J. Biol. Chem. 275: 25608-25615.
Sieb, J.P., Kraner, S., Schrank, B., Reitter, B., Goebel, H.H., Tzartos, S. J. and Steinlein, O.K. (2000). Severe congenital myasthenic syndrome due to homozygosity of the 1293insG ε-AChR subunit mutation. Ann. Neurol. 48:379-83
Fostieri, E., Beeson, D. and Tzartos, S.J. (2000). The conformation of the main immunogenic region on the α-subunit of muscle acetylcholine receptor is affected by neighboring receptor subunits. FEBS Lett. 481: 127-130.
Poulas, K., Tsibri, E., Papanastasiou, D., Tsouloufis, T., Marinou, M., Tsantili, P., Papapetropoulos, T., and Tzartos, S.J. (2000). Equal male and female incidence of myasthenia gravis. Neurology, 54, 1202-1203.
Nenninger, R., Schultz, A., Helmreich, M., Wilisch, A., Vandekerckhove, B., Hunig, T., Schalke, B., Tzartos, S.J., Kahlbacher, H., Muller-Hermelink, H. and Marx, A. (1998). Abnormal thymocyte development – Generation of autoaggressive T-cells in mixed and cortical thymomas. Lab. Invest. 78:743-753.
Tsantili, P., Tzartos, S.J. and Mamalaki, A. (1999) High affinity scFv antibody fragments protecting the human nicotinic acetylcholine receptor. J. Neuroimmunol. 94: 15-27.
Papanastasiou, D., Mamalaki, A., Eliopoulos, E., Poulas, K., Liolitsas Ch. and Tzartos, S.J. (1999). Construction and characterization of a humanized single chain Fv antibody fragment against the main immunogenic region of the acetylcholine receptor. J. Neuroimmunol. 94: 182-195.
Tzartos, S.J. and Remoundos, M. (1999). Detection of antibodies directed against the cytoplasmic region of the human acetylcholine receptor in sera from myasthenia gravis patients. Clin. Expl. Immunol. 116: 146-152.
Skok, M.V., Voitenko, L. P., Voitenko, S. V., Lykhmus, E. Yu., Kalashnik, E. N., Litvin, T. I., Tzartos S. J. and Skok, V. I. (1999). Alpha subunit composition of nicotinic acetylcholine receptors in the rat autonomic ganglia neurons as determined with subunit-specific anti-α(181-192) peptide antibodies. Neuroscience. .93: 1436-1447.
Wilisch, A., Gutsche, S., Hoffacker, V., Schultz, A., Tzartos, S., Nix, W., Schalke, B., Schneider, C., Muller-Hermelink, H. K. and Marx A. (1999). Association of acetylcholine receptor α-subunit expression in mixed thymoma with myasthenia gravis. Neurology. 52: 1460-1466.
Schultz, A., Hoffacker, V.,Wilisch, A., Nix, W., Schalke, B., Nix, W., Tzartos, S., Muller-Hermelink, H. K. and Marx A. (1999). Neurofilament is an autoantigenic determinant in myasthenia gravis. Ann. Neurology. 46: 167-75.
Martin-Ruiz, C.M., Court, J.A., Molnar, Ε., Lee, Μ., Gotti, C., Mamalaki, A., Tsouloufis, T., Tzartos, S., Ballard, C., Perry, R.H. and Perry, E.K. (1999) Alpha 4 but not alpha 3 and 7 nicotinic acetylcholine receptor subunits are lost from the temporal cortex in Alzheimer’s disease. J. Neurochem. 73: 1635-1640.
Jacobson, L., Beeson, D., Tzartos, S. and Vincent, A. (1999). Monoclonal antibodies raised against human acetylcholine receptor bind to all five subunits of the fetal isoform. J. Neuroimmunol. 98: 112-120.
Wakkach, A., Poea, S., Chastre, E., Gespach, C., Lecerf, F., De la Porte, S., Tzartos, S., Coulombe, A., and Berrih-Aknin, S. (1999). Establishment of a thymic myoid cell line: phenotypic and functional characteristics. Am. J. Pathol. 155:1229-1240
Sieb, J.P., Dorfler, P., Tzartos, S., Wewer, U., Ruegg, M.,Meyer, D., Baumann, I., Lindemuth, R., Jakschik, J. and Ries, F. (1998). Congenital myasthenic syndromes in two kinships with endplate acetylcholine receptor and utrophin deficiency. Neurology, 50: 54-61.
De la Porte, S., Chaubourt, E., Fabre, F., Poulas, K., Chapron, J., Eymard, B., Tzartos, S.J., and Koenig, J. (1998). Accumulation of acetylcholine receptors is a necessary condition for normal accumulation of acetylcholinesterase during in vivo neuromuscular synaptogenesis. Eur. J. Neurosci., 10: 1631-1643.
Barchan, D., Asher, O., Tzartos, S.J., Fuchs, S. and Souroujon, M. (1998). Modulation of the anti-acetylcholine receptor and experimental autoimmune myasthenia gravis by recombinant fragments of the acetylcholine receptor. Eur. J. Immunol. 28:616-624.
Gattenloehner, S., Vincent, A., Leuschner, I., Tzartos, S., Kirchner, T., Muller-Hermelink, H.-K., Marx, A. (1998) Investigation of the acetylcholine receptor in rhabdomyosarcomas as compared with other childhood tumors. Am. J. Pathol. 152: 437-444.
Guyon, T., Wakkach, A., Klingel-Schmitt, I., Levasseur, P., Beeson, D., Asher, O., Tzartos, S.J. and Berrih-Aknin, S. (1998). Regulation of acetylcholine receptor gene expression in human myasthenia gravis muscles. Evidence for a compensatory mechanism triggered by receptor loss. J. Clin. Invest. 102: 249-263.
Orlewski, P., Marraud, M., Cung, M.T, Tsikaris, V., Sakarellos-Daitsiotis, M., Sakarellos, K., Vatzaki, E. and Tzartos, S.J. (1996). Compared structures of the free AChR MIR decapeptide and the antibody-bound [A76]MIR analogue. A molecular dynamics simulation from 2D-NMR data. Biopolymers (Peptide Science). 40: 419-432.
Gotti, C., Balestra, B., Mantegazza, R., Tzartos, S., Moretti, M. & Clementi, F. (1997) Detection of antibody subpopulations in myasthenia gravis using a non radioactive new enzyme immunoassay. Muscle & Nerve, 20: 800-808.
Loutrari, H., Kokla, A., N. Trakas and Tzartos, S.J. (1997). Expression of human-Torpedo hybrid acetylcholine receptors for analyzing the antigenic specificities in myasthenic antisera. Clin. Expl. Immunol. 109, 538-546.
Andre, F., Marraud, M., Tsouloufis, T., Tzartos, S.J., Boussard, G. (1997) Triphosgene: An efficient carbonylating agent for liquid and solid-phase aza-peptide synthesis. Application to the synthesis of two aza-analogues of the AChR MIR decapeptide. J. Pep. Science . 3: 429-441
Voltz, R., Kamm, C., Padberg, F., Malotka, J., Kerschensteiner, M., Spuler, S., Tzartos, S., and Dornmair, K. (1997) Highly purified oligo-His tagged human recombinant alpha(1)-AChR is immunogenic in vivo and suitable for T cell stimulation in vitro in experimental and human myasthenia gravis. J.Neuroimmunol. 80:131-136.
Bufler, J., Kahlert, S., Tzartos, S.J., Toyka, C. and Franke, C. (1996). Activation and blockage of nicotinic channels by antibodies directed against the binding site of the acetylcholine receptor. J. Physiol. 492: 107-114
Kontou, M., Vatzaki, E.H., Kokla, A., Acharya, K.R., Oikonomakos, N.G. and Tzartos, S.J. (1996). Characterisation, crystallisation and preliminary X-ray diffraction analysis of a Fab fragment of a rat monoclonal antibody with very high affinity for the human muscle acetylcholine receptor. FEBS Lett. 389: 195-198.
Wakkach, A., Guyon, T., Bruand, C., Tzartos, S., Cohen-Kaminsky, S. and Berrih-Aknin, S. (1996) Expression of acetylcholine receptor genes in human thymic epithelial cells. Implication for myasthenia gravis. J. Immunol. 157: 3752-3760.
Pappas, I.S., Sophianos, D., Tzartos, S.J. and Tsiftsoglou, A.S. (1996). Expression of memory, differentiation and repression of c-myc and p53 genes in human RD/TE-671 cells induced by a uveido-derivative of pyridine (UDP-4). Cell Growth and Differentiation. 7: 797-809.
Tsikaris, V., Sakarellos, C., Sakarellos-Daitsiotis, M., Orlewski, P., Marraud, M. Cung, M.T., Vatzaki, E., and Tzartos, S.J. (1996). Construction and application of a new class of sequential oligopeptide carriers for multiple anchoring of antigenic peptides. Application to the AChR main immunogenic region. Intern. J. Biol. Macromol. 19: 195-205.
Tzartos, S.J., Kouvatsou, R. and Tzartos E. (1995) Monoclonal antibodies as site-specific probes for the acetylcholine receptor δ-subunit tyrosine and serine phosphorylation sites. Eur. J. Biochem. 228, 463-472.
Mapouras, D., Philippou, G., Charalabous, S., Tzartos, S.J. Balafas, A., Souvatzoglou, A. and Lymberi, P. (1995). Antibodies to acetylcholinesterase cross-reacting with thyroglobulin in myasthenia gravis and graves disease. Clin. Exp. Immunol 100: 336-343.
Tzartos, S.J., Tzartos, E., and Tzartos, J.S. (1995) Monoclonal antibodies against the acetylcholine receptor γ-subunit as site specific probes for receptor tyrosine phosphorylation. FEBS Letters. 363: 195-198.
Mamalaki, A., Boutou, E., Hurel, C., Patsavoudi, E., Tzartos, S.J. and Matsas, R. (1995). The BM88 antigen, a novel neuron-specific molecule, promotes the differentiation of mouse neuroblastoma cells. J. Biol. Chem. 270: 14201-14208.
Asher, O., Kues, W.A., Witzemann, V.,Tzartos, S.J., Fuchs, S. and Souroujon, M.C. (1993) Increased gene expression of acetylcholine receptor and myogenic factors in passively transferred experimental autoimmune myasthenia gravis. J. Immunol. 151, 6442-6450.
Schmutz, M., Kling, D., Tzartos, S.J. and Brisson, A. (1994). A mixed ELISA-immunoelectron microscopy approach for studying epitope topology of membrane proteins: application to the acetylcholine receptor. J. Histochem. Cytochem. 42, 315-327 (1994).
Tzartos, S.J., Valcana, C., Kouvatsou, R., and Kokla, A. (1993) The tyrosine phosphorylation site of the acetylcholine receptor β-subunit is located in a highly immunogenic epitope implicated in channel function. Antibody-probes for β subunit phosphorylation and function. EMBO J. 12, 5141-5149.
Papadouli, I., Sakarellos, C.,and Tzartos, S.T. (1993). High resolution epitope mapping and fine antigenic characterization of the main immunogenic region of the acetylcholine receptor. Improving the binding activity of synthetic analogues of the region. Eur. J. Biochem. 211, 227-234.
Eleftheriou, C.S., Trakas, N., Kokla, A. and Tzartos, S.J. (1993). A group of three fibroblast secreted polypeptides suppressed by cellular ageing and interferon-γ. Bioch. Bioph. Acta. 1180, 304-312.
Detsikas, E., Tsikaris, V., Sakarellos-Daitsiotis, M., Sakarellos, C., Cung, M.T., Marraud, M., Vatzaki, E. and Tzartos, S.J. (1993). Cyclic lactam analogues containing the main immunogenic region of Torpedo acetylcholine receptor. Peptide Research 6, 17-23.
Tsikaris, V., Detsikas, E., Sakarellos-Daitsiotis, M., Sakarellos, C., Vatzaki, E., Tzartos, S.J., Marraud, M. and Cung, M.T., (1993). Conformational requirements for molecular recognition of ACh receptor MIR analogues by monoclonal anti-MIR antibody: A 2D-NMR and molecular dynamics approach. Biopolymers. 33, 1123-1134.
Mamalaki, A., Trakas, N., and Tzartos, S.J. (1993). Bacterial expression of a single-chain Fv fragment which efficiently protects the acetylcholine receptor against antigenic modulation caused by myasthenic antibodies. Eur. J. Immunol. 23, 1839-1845.
Melms, A., Weissert, R., Klinkert, W.E.F., Schalke, B.C.G., Tzartos, S. and Wekerle, H. (1993). Specific immune complexes augment in vitro acetylcholine receptor-specific T-cell proliferation. Neurology 43, 583-588.
Vatzaki, E. H., Acharya, K.R., Oikonomakos, N. G. and Tzartos, S.J. (1993). Crystallization and preliminary crystallographic study of an Fab fragment of a pathogenic rat monoclonal antibody against the nicotinic acetylcholine receptor. Protein Science. 2: 1770-1772.
Loutrari, H., Tzartos, S.J. and Claudio, T. (1992). Use of Torpedo-mouse hybrid acetylcholine receptors reveals immunodominance of the α-subunit in myasthenia gravis antisera. Eur. J. Immunol. 22, 2949-2956.
Loutrari, H., Kokla, A. and Tzartos, S.J. (1992). Passive transfer of experimental myasthenia gravis via antigenic modulation of acetylcholine receptor. Eur. J. Immunol. 22, 2449-2452.
Zhang, Y., and Tzartos, S.J. (1992). B-T lymphocyte interactions in experimental autoimmune myasthenia gravis. Autoantibody mediated up-regulation of the response of AChR-specific T-lymphocytes. Immunology 77, 571-576.
Marx, A., Osborn, M., Tzartos, S., Geuder, K.I., Schalke, B., Nix, W., Kirchner, T., and Muller-Hermelink, H.K. (1992). A striational muscle antigen and myasthenia gravis-associated thymomas share an acetylcholine receptor epitope. Develop. Immunol. 2, 77-84.
Cung, M.T., Demange, P., Marraud, M., Tsikaris, V., Sakarellos, C., Papadouli, I., Kokla, A., Tzartos, S.J. (1991). Two-dimentional 1H-NMR study of antigen-antibody interactions: binding of synthetic decapeptides to an anti-acetylcholine receptor monoclonal antibody. Biopolymers. 31, 769-776.
Verschuuren, J.J.G.M., Graus Y.M.F., Bos N.A., Tzartos S.J., Van Breda Vriesman P.J.C., and De Baets M.H. (1991). Paratope and framework related idiotopes on acetylcholine receptor antibodies. J. Immunol. 146, 941-948.
Verschuuren, J.J.G.M., Graus Y.M.F., Van Breda Vriesman P.J.C., Tzartos S.J., and De Baets M.H. (1991). In vivo effects of neonatal administration of anti-idiotype antibodies on experimental autoimmune myasthenia gravis Autoimmunity. 10:173-179.
Tzartos, S. J., Loutrari, H., Tang, F., Kokla, A., Walgrave, S., Milius, R. P. and Conti-Tronconi, B. (1990). Main immunogenic region of Torpedo electroplax and human muscle acetylcholine receptor. Localization and micro-heterogeneity reveiled by the use of synthetic peptides. J. Neurochem. 54, 51-61.
Plinkert, P.K., Gitter, A.H., Zimmermann, U., Kirchner, T., Tzartos, S. and Zenner, H.P. (1990). Visualization and functional testing of acetylcholine receptor-like molecules in cochlear outer hair cells. Hearing Res. 44, 25-34.
Marx, A., O’ Connor, R., Geuder, K.I., Hoppe, F., Schalke, B., Tzartos, S., Kalies, I., Kirchner, T., and Muller-Hermelink, H. K. (1990). Characterization of a protein with an acetylcholine receptor epitope from myasthenia gravis-associated thymomas. Lab. Invest.. 62, 279-286.
Tzartos, S.J., Efthimiadis, A., Morel, E. and Bach, J.F. (1990) Neonatal myasthenia gravis: antigenic specificities of antibodies in sera from mothers and their infants. Clin. Exp. Immunol. 80, 376-380.
Papadouli, I., Potamianos, S., Hadjidakis, I., Bairaktari, H., Tsikaris, V., Sakarellos, C., Cung, M.T., Marraud, M. and Tzartos, S.J. (1990). Antigenic role of single residues within the main immunogenic region of the nicotinic acetylcholine receptor. Biochem. J. 269, 239-245.
Tzartos, S.J and Remoundos, M.S. (1990). Fine localization of the major α-bungarotoxin binding site to residues α189-195 of the Torpedo acetylcholine receptor. Residues 189, 190 and 195 are indispensable for binding. J. Biol. Chem. 265, 21462-21467.