Serum complement levels as prognostic marker for monitoring treatment response in lupus nephritis

Abstract

Background: Lupus nephritis (LN) is one of the most common and serious manifestations of systemic lupus erythematosus (SLE) that causes significant morbidity and mortality. Certain biomarkers for LN are sometimes able to assess treatment response in lupus nephritis. This study aimed to compare serum complement levels (C3 and C4) as markers of treatment response of LN and their relation to the LN class in renal biopsy.

Methods: This prospective observational study was conducted in the Department of Nephrology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh from July 2018 to August 2019. Twenty seven patients who were diagnosed with LN after kidney biopsy were included in this study. Serum complement levels (C3 and C4), 24 hours urinary total protein (24-hr UTP) and anti-double-stranded DNA (anti-ds DNA) were measured in all patients at baseline, 3 months and 6 months after treatment initiation. These biomarker values before and after treatment were compared between the proliferative and non-proliferative LN patients.

Results: Serum C3 levels were significantly different between patients with proliferative LN (Class III and Class IV) and non-proliferative LN (Class V) at baseline (0.47 ± 0.32 g/l versus 0.89 ± 0.43 g/l, p=0.009) and levels changed significantly 6 months after treatment initiation (p<0.001) and likewise for serum C4 levels (0.10 ± 0.06 g/l versus 0.24 ± 0.26 g/l, p=0.040). The values of 24-hr UTP and anti-ds-DNA were significantly different 6 months after treatment with p value <0.05 in both groups but C3 (p<0.001) and renal Systemic Lupus Erythematosus Disease Activity Index (rSLEDAI) (p<0.001) were only significant in the proliferative group. On the other hand, after 6 months treatment, C4 levels became relatively higher but that was not significant in both groups (p>0.05).

Conclusion: After 6 months of treatment, serum C3 and C4 levels increased towards normal in both LN groups. Serum C3 and C4 levels in patients with LN correlate with disease activity. Therefore, serum complement (C3 and C4) levels may be utilized as serological biomarkers for treatment response of LN.

Birdem Med J 2021; 11(2): 97-102