BXSB-type genome causes murine autoimmune glomerulonephritis: pathological correlation between telomeric region of chromosome 1 and Yaa.

The autoimmune-prone BXSB/MpJ-Yaa mouse is a model of membranous proliferative glomerulonephritis (MPGN). Severe MPGN has been reported only in male BXSB/MpJ-Yaa mice because of the Y-linked autoimmune accelerator (Yaa) locus. However, we show that female BXSB/MpJ mice develop age-related MPGN without Yaa. Female BXSB/MpJ mice clearly developed MPGN characterized by increased mesangial cells, thickening of the glomerular basement membrane (GBM), double contouring and spike formation of GBM with T-cell infiltrations and podocyte injuries corresponding with increased autoantibody production and albuminuria. Analysis of the renal levels of the Fc gamma receptor (Fcgr) and interferon-activated gene 200 (Ifi200) family genes, which are MPGN candidate genes localized to the telomeric region of chromosome 1 (Chr.1), showed that Fcgr2b levels decreased, whereas Fcgr3 and Ifi202b levels increased in female BXSB/MpJ mice compared with healthy C57BL/6 mice. Furthermore, in isolated glomeruli, microarray analysis revealed that Fcgr3, Fcgr4 and Ifi202b expression was higher in male BXSB/MpJ-Yaa mice than in male BXSB/MpJ mice. These findings indicate that the BXSB/MpJ-type genome causes age-related MPGN with significant contribution from the telomeric region of Chr.1, and Yaa enhances the expression of genes localizing to this locus, thereby leading to severe MPGN in male mice.

IgA nephropathy in a patient with systemic lupus erythematosus.

Systemic lupus erythematosus is generally recognized to be a multisystem autoimmune disease with kidney involvement. However, the occurrence of other non-lupus glomerulopathies has been rarely reported in patients with systemic lupus erythematosus. It is well known that lupus nephritis may switch over time to another class according to the World Health Organization classification. It seems likely that IgA nephropathy is a clinical characteristic of a particular subset of patients with systemic lupus erythematosus. We report a 22-year-old Japanese man with recurrence of proteinuria. The renal flare occurred when he was without lupus clinical and serological activity, and renal remission was only obtained with angiotensin-converting enzyme inhibitor and angiotensin II receptor blocker therapy. Although the incidence of IgA nephropathy is high in Japan, we believe that this is the first report of a Japanese patient in which lupus nephritis switched over time to IgA nephropathy.