Antibodies against monomeric C-reactive protein - a promising biomarker of lupus nephritis?

Abstract Objective and aim A significant incidence of systemic lupus erythematosus (SLE), the severity of lupus nephritis and varying responses to treatment rationalize the search for novel biomarkers of disease activity. The aim of the study was to assess whether antibodies against monomeric C reactive protein (anti-mCRP) are associated with the presence of lupus nephritis, correlate with disease activity, and whether they can serve to evaluate a response to treatment. Methods The study involved 74 patients with lupus nephritis, 29 patients with systemic lupus without renal involvement and 31 patients with primary glomerulonephritis; the control group included 31 healthy volunteers. Interleukin-6 and tumor necrosis factor alpha were measured using commercially available ELISA tests. The presence of anti-mCRP in the serum was tested with the use of in-house ELISA. Results The highest prevalence and concentrations of antibodies against monomeric C-reactive protein were observed among patients with lupus nephritis, as compared to other groups. The elevated level of anti-mCRP was associated with standard clinical and laboratory indicators of SLE activity. Moreover, the highest concentrations of both Il-6 and TNF-α were observed for patients with the most severe nephropathy. A significant decrease in anti-mCRP and cytokines' levels in the course of treatment was observed. Conclusion The study gives further evidence that antibodies against monomeric C-reactive protein may be considered an indicator of renal involvement in patients with SLE. Assessment of anti-mCRP supports monitoring of disease activity and can be used in evaluating the treatment effectiveness.