AMA production in primary biliary cirrhosis is promoted by the TLR9 ligand CpG and suppressed by potassium channel blockers.
We previously reported that peripheral blood mononuclear cells (PBMCs) from patients with primary biliary cirrhosis (PBC) produce significantly higher levels of polyclonal IgM than controls after exposure to CpG. Furthermore, the prevalence and unusually high levels of antimitochondrial antibodies (AMAs) in patients with PBC suggest a profound loss ofB cell tolerance. We have addressed the issue of whether CpG will promote the production ofAMAs and whether new experimental agents that inhibit the lymphocyte potassium channels Kv1.3 and KCa3.1 can suppress CpG-mediated B cell activation and AMA production. PBMCs were stimulated with and without CpG and were subsequently analyzed for phenotype, including expression of TLR9, CD86, and KCa3.1 concurrent with measurements of AMA and responses to a control antigen, tetanus toxoid, in supernatants. Additionally, K+ channel expression on B cells from PBC patients and controls was studied using whole-cell patch-clamp technology. In patients with PBC, CpG induces secretion of AMAs in PBMCs andalso up-regulates B cell expression of TLR9, CD86, and KCa3.1. Additionally, K+ channel blockers suppress secretion of AMA without a reduction of CpG-B-enhanced IgM production. Furthermore, there is diminished up-regulation of TLR9 and CD86 without affecting proliferation of B cells, B cell apoptosis, or viability.


CONCLUSIONS
These data suggest that the hyperresponsiveness of B cells in PBC accelerates B cell-mediated autoimmunity.
Moritoki
Yuki
Y
Division of Rheumatology, Allergy, and Clinical Immunology and the University of California at Davis, Davis, CA 95616, USA.
Lian
Zhe-Xiong
ZX
Wulff
Heike
H
Yang
Guo-Xiang
GX
Chuang
Ya-Hui
YH
Lan
Ruth Y
RY
Ueno
Yoshiyuki
Y
Ansari
Aftab A
AA
Coppel
Ross L
RL
Mackay
Ian R
IR
Gershwin
M Eric
ME
D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000276:immunology / Q000378:metabolism*; D015551:Autoimmunity; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D051940:B7-2 Antigen / Q000378:metabolism; D016022:Case-Control Studies; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007075:Immunoglobulin M / Q000378:metabolism; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000187:drug effects / Q000378:metabolism; D051664:Kv1.3 Potassium Channel / Q000187:drug effects / Q000378:metabolism; D008024:Ligands; D008105:Liver Cirrhosis, Biliary / Q000276:immunology / Q000378:metabolism*; D008213:Lymphocyte Activation; D008875:Middle Aged; D008928:Mitochondria / Q000276:immunology*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D051217:Toll-Like Receptor 9 / Q000378:metabolism*; D015534:Trans-Activators; D015854:Up-Regulation
D001323:Autoantibodies; D051940:B7-2 Antigen; C409062:CXXC1 protein, human; D004268:DNA-Binding Proteins; D007075:Immunoglobulin M; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; C496923:KCNN4 protein, human; D051664:Kv1.3 Potassium Channel; D008024:Ligands; D026902:Potassium Channel Blockers; C495371:TLR9 protein, human; D051217:Toll-Like Receptor 9; D015534:Trans-Activators