Anti-MOG antibodies are under polygenic regulation with the most significant control coming from the C-type lectin-like gene locus.

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system that is genetically complex. There is evidence supporting a role of myelin oligodendrocyte glycoprotein (MOG) humoral immunity in MS. We aimed to determine the genetic regulation of anti-MOG antibodies and their involvement in disease, by using MOG-induced experimental autoimmune encephalomyelitis (EAE) in rat, an animal model that closely mimics human MS. We show polygenic regulation of anti-MOG antibodies in two backcross populations, including a major genetic determinant for antibody expression on chromosome 4, Amig3. We fine-mapped the region to 539 kilobases (kb) consisting of a complex of seven C-type lectin receptor genes (Dcir4, Dcir3, Dcir2, Dcir1, Dcar1, Mcl and Mincle) that was captured in the APLEC congenic strain. We confirmed that Amig3 regulates anti-MOG antibody levels in MOG-EAE, and further showed that immune reactions during initiation of EAE were skewed toward increased numbers of B cells in the EAE-protected APLEC strain, together with higher anti-MOG IgG1 and lower IgG2b levels. Taken together, our data demonstrated complex regulation of the antibody response during EAE and that skewing the antibody response toward Th2 contributed to protection from EAE.

RGMA and IL21R show association with experimental inflammation and multiple sclerosis.

Rat chromosome 1 harbors overlapping quantitative trait loci (QTL) for cytokine production and experimental models of inflammatory diseases. We fine-dissected this region that regulated cytokine production, myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), anti-MOG antibodies and pristane-induced arthritis (PIA) in advanced intercross lines (AILs). Analysis in the tenth and twelfth generation of AILs resolved the region in two narrow QTL, Eae30 and Eae31. Eae30 showed linkage to MOG-EAE, anti-MOG antibodies and levels of interleukin-6 (IL-6). Eae31 showed linkage to EAE, PIA, anti-MOG antibodies and levels of tumor necrosis factor (TNF) and IL-6. Confidence intervals defined a limited set of potential candidate genes, with the most interesting being RGMA, IL21R and IL4R. We tested the association with multiple sclerosis (MS) in a Nordic case-control material. A single nucleotide polymorphism in RGMA associated with MS in males (odds ratio (OR)=1.33). Polymorphisms of RGMA also correlated with changes in the expression of interferon-gamma (IFN-gamma) and TNF in cerebrospinal fluid of MS patients. In IL21R, there was one positively associated (OR=1.14) and two protective (OR=0.87 and 0.68) haplotypes. One of the protective haplotypes correlated to lower IFN-gamma expression in peripheral blood mononuclear cells of MS patients. We conclude that RGMA and IL21R and their pathways are crucial in MS pathogenesis and warrant further studies as potential biomarkers and therapeutic targets.