Potential diagnostic biomarkers for IgA nephropathy: a comparative study pre- and post-tonsillectomy.

OBJECTIVE: The proteins BAFF, ST6GALNAC2, C1GALT1, and COSMC in peripheral blood mononuclear cells (PBMCs) and plasma levels of IgA1 and galactose-deficient IgA1 (Gd-IgA1) are potential biomarkers for IgAN nephropathy. In this study, we comparatively studied the changes of those biomarkers before and after tonsillectomy.

METHODS: Peripheral blood samples were obtained from 16 IgAN patients with pre- and post-tonsillectomy. IgAN was diagnosed based on results from analysis of percutaneous renal biopsy tissue. Peripheral blood samples from three patients without renal diseases (non-IgAN), before and after tonsillectomy, and 16 healthy controls were also examined. BAFF, ST6GALNAC2, C1GALT1, and COSMC mRNA levels in PBMCs were detected using real-time PCR. Plasma IgA1 content was measured by ELISA. Gd-IgA1 levels were determined using the VV lectin-ELISA method.

RESULTS: BAFF, ST6GALNAC2, C1GALT1, and COSMC mRNA levels and the plasma concentrations of IgA1 and Gd-IgA1 in IgAN patients before tonsillectomy were significantly higher than those in healthy controls (P < 0.05). Tonsillectomy significantly increased the expression of BAFF and ST6GALNAC2, and plasma IgA1 level, while it downregulated that of C1GALT1 and COSMC (P < 0.05). However, in non-IgAN patients, tonsillectomy did not affect the mRNA levels of BAFF, ST6GALNAC2, C1GALT1, and COSMC, plasma IgA1 content and Gd-IgA1 level. Positive correlations were established between BAFF and IgA1 (r = 0.604, P < 0.01) and between ST6GALNAC2 and Gd-IgA1 (r = 0.623, P < 0.01).

CONCLUSIONS: Tonsillectomy changes the mRNA levels of BAFF, ST6GALNAC2, C1GALT1, and COSMC in PBMCs, as well as the plasma IgA1 level in IgAN patients. BAFF and ST6GALNAC2 might regulate IgA1 secretion and O-glycosylation.