De-sialylated and sialylated IgG anti-dsDNA antibodies respectively worsen and mitigate experimental mouse lupus proteinuria and possible mechanisms

Abstract

BackgroundThe role of sialylated and de-sialylated (de-SIA) IgG anti-dsDNA antibodies in experimental mouse lupus remains unclear. Aim of the studyTo examine how sialylated and de-SIA IgG anti-dsDNA antibodies affect lupus mouse proteinuria and possible mechanisms. MethodsBlood was serially obtained from pristane-induced female BALB/c lupus mice to assess correlations between alpha-2,6-sialic cid (SIA) ratios of serum IgG anti-dsDNA and proteinuria. Kidney C3 staining was correlated with blood IgG anti-dsDNA. Sialylated IgG anti-dsDNA with its de-SIA form was administered to determine the effect on lupus proteinuria and in vitro consequences. ResultsWe observed that the SIA contents of IgG anti-dsDNA were lower in Week 16/1+ (Week 16 with 1 + proteinuria) and W24/2 + mice than those in W16 (no proteinuria) and W24/1 + mice, respectively (P < 0.005 for both). C3 staining densities in the kidney correlated inversely with the α-2,6-SIA content of plasma IgG anti-dsDNA (r = -0.660). Highly sialylated A52L1 IgG anti-dsDNA injection mitigated lupus proteinuria significantly from PBS injection; however, its de-SIA form worsened proteinuria (aggravation of proteinuria: the latter vs. the former [sialylated A52L1 IgG anti-dsDNA] with an infinite odds ratio). Highly sialylated A52L1 IgG anti-dsDNA resulted in higher interleukin (IL)-10/IL-12 ratios, higher transforming growth factor-β1 levels, and lower tumor necrosis factor-α levels in sera than its de-SIA from. ConclusionWe concluded that a low SIA/serum IgG anti-dsDNA ratio indicated a high severity of nephritis in pristane-induced lupus mice. Highly sialylated IgG anti-dsDNA, in contrast to the de-SIA form, alleviated the severity of lupus proteinuria.