Anti-Pentraxin 3 autoantibodies in systemic lupus erythematosus: A comparative study of patients with and without proteinuria

Abstract

Background and objectives: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease frequently complicated by renal involvement, known as lupus nephritis (LN). Pentraxin 3 (PTX3) is an acute-phase protein implicated in immune regulation, and autoantibodies against PTX3 (anti-PTX3) have been hypothesized to exert a protective effect against the development of LN in SLE patients. The objective of the current study was to evaluate serum levels of anti-PTX3 IgG and anti-double-stranded DNA (anti-dsDNA) IgG antibodies in SLE patients and to assess their association with disease activity and proteinuria. Methods: This cross-sectional study included 69 participants divided into three groups: SLE patients with proteinuria, SLE patients without proteinuria, and healthy controls. Serum IgG anti-PTX3 and anti-dsDNA levels were measured using enzyme-linked immunosorbent assay (ELISA). Proteinuria was assessed by measuring the albumin-to-creatinine ratio (A/Cr). Associations between antibody levels, proteinuria, and disease activity index were analyzed. Results: Serum anti-PTX3 levels were highest in SLE patients without proteinuria, with a statistically significant difference among the three groups ( p = 0.031). Anti-dsDNA antibodies were detected exclusively in SLE patients; however, no significant difference was observed between patients with and without proteinuria ( p = 1.00). Anti-PTX3 levels demonstrated a weak negative correlation with A/Cr (r = −0.082) and with disease activity index (r = −0.142). Conclusions: Higher anti-PTX3 levels in SLE patients without proteinuria and their inverse relationship with proteinuria and disease activity were observed in this cross-sectional sample; however, these correlations were weak and not statistically significant, and a protective or causal role cannot be established from these data. Anti-PTX3 may represent a candidate marker warranting longitudinal validation in patients with SLE.

Keywords

anti-dsDNA antibody / anti-PTX3 / ELISA / lupus nephritis / proteinuria / systemic lupus erythematosus

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