6Electronmicroscopy Study of NMJ of an MG Patient Engel et al.Mayo clinic proc. 52:267, 1977
7AChR is a transmembrane glycoprotein formed by five homologous subunits in the stoichiometry a2bgd or a2bed. The molecular weights of the subunits range between 45 and 55 kDa.The a subunit is Considered to be the highly immunogenic region.
10Molecular Mechanisms of EAMG Damage to the neuromuscular junctionComplement activationAChRAPCIL-1, IL-12CD4Class IIPeptide(a )CD4TCRB7CD 28CD40L/CD40AChR-specific memory T cellProliferation and DifferentiationIL-10, TNF-a, IL-6,IL-12, IL-18AChR-specific memory B cellsAChR-AbPlasma cellsNKIFN-gIL-18B
14RED -bungarotoxin binding (NMJ) GREEN C3, MAC or IgG deposits IF Studies Reveal IgG Deposits But Not C3 or MAC Deposits at the NMJs of Mice with C3 or C4 DeficiencyC4+/+C4-/-C3-/-C3MACIgGRED -bungarotoxin binding (NMJ)GREEN C3, MAC or IgG depositsTuzun –ChristadossJ. Immunol. 171:3847, 2003
15Immune Intervention Disease specific Antigen/organ specific I. AChR T cell epitope toleranceII. AChR B cell epitope toleranceDisease specificI. Anti-Proinflammatory Cytokinea. Soluble TNFR (etanercept)b. IL1-Rac. Anti-IL-6II. Blocking classical complement pathwaya. Anti C1q/C2/C4
20Anti-C1q Ab Treatment Suppresses AChR and Dominant Peptide Specific IL-6 Production
21Effect of Cytokine Deficiencies in Clinical EAMGNormalIL-4IL-10Gene DepletionIFN-gAnti-AChR AbDiseaseIL-12IL-18IL-6TNF-a p55p7520406080100120% clinical disease and anti-AChR antibodies
22IL-6 and TNF in EAMG Th Th B B TNF TNF AChR specific IL6 IL-6 GC formationActivation of B cells and generation of effector B cells.Potentiates production of IgG anti-AChR antibodies (pathogenic)BBActivates C3Promotes EAMG pathology
23Targeting ProinflammatorCytokines A. Soluble Recombinant HumanTNFR (Etanercept)
27A pilot Trial of Etanercept in the Treatment of Steroid-Dependent MG *+ Mean change in QMG score from basline at 6 months was (p=0.041).Mean change in MMT at 6 months was (p=0.020).Mean decrease in prednisone dose from baseline to end of study was 17.5 mg/48 hr dose (p=0.0084).Etanercept was well tolerated, and no severe adverse reaction observed+ 11 patients enrolled; 8 completed, and 2 patients withdrawn due to disease worsening.
28Immunological Effect of Etanercept No reduction in plasma anti-AChR antibody.Peripheral blood CD4 and B cell (CD19+) counts rose steadily during the 24 week study.Patients who had higher increases in their cytokine levels had a worse outcome.
29Targeting ProinflammatorCytokines b. Recombinant Human IL1-Ra
30Activation of the Adaptive Immune System with IL-1
31IL-1Ra Treatment Prevents Clinical EAMG stoppedYang –Christadoss, J. Immunol.175:2018, 2005
32IL-1Ra Treats EAMG Yang –Christadoss, J. Immunol. 175:2018, 2005 P<0.05P<0.05P<0.05
33Possible Consequence of Down Regulating IL-1 by IL-1Ra in Mice with Clinical EAMG CD40L, OX40 Expression on T cellsInflammatory cytokinesIFN-g, IL-2, IL-1, IL-6, TNF-aAnti-AChR IgG , IgG1 and C3Anti-AChR antibodies and complementmediated NMJ pathology
34IL-6 in MG: Multiple Hit AChR Specific NMJ CD4 IL-6 B IgG2b -C1q C4-C3-C5-9C3
35IL-6 – A Danger Molecule in EAMG ! 1. IL-6 deficient mice are resistant to EAMG and produce less C32. C3 and FCγRIII deficient mice are resistant to EAMG and produce less IL-63. Amelioration of EAMG following anti-C1q treatment is associated with reduced IL-6
36Anti-IL-6 Ab Treatment Reduces the Incidence of EAMG Days after second immunization
37Anti-IL-6 Ab Treatment Suppresses Serum Anti-AChR IgG and IgG2b Ab
38Anti-IL-6 Ab Treatment Suppresses AChR Specific Cytokine Production
39Classical Complement Pathway and IL-6 in EAMG Pathogenesis anti-AChR antibody productionT helperB cellAntigen presenting cellAChRIL-6C3Immune complex formationAChRC1qC1rC1sC1qFcγRIII activationClassical complement pathway activationStimulation ofIL-6, C1q and C3 productionMembrane attack complex formation
40Balancing the Immune System to Treat Autoimmune Disease (MG) IL-6, TNFC3-C5b-C9Anti-AChR IgGIL-6, TNF-normal levelHealthySuppress anti-AChRand C5b-C9
43MG Lab - Galveston Collaborators Huan Yang Bo Wu Stephen Higgs Erdem Tuzun1,2Shamsher SainiAndrey BednovBen Scott 3Jing Li1Iris Wingrow3Huibin QiXiarong WuCollaboratorsHuan YangBo WuStephen HiggsTian Lin XioGalen KaufmannMat MerigioliJuli Rowin1MG foundation Osserman/Sosin/McClure Post doctoral Fellows1,2MDA Research Career Award Recipients3 MG Foundation Henry Viets FellowSupported by NIH,MDA, AFM,and MG Foundation