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Updated: Jul 12, 2025
Analyses of Proteinuria, Renal Infiltration of Leukocytes, and Renal Deposition of Proteins in Lupus-prone MRL/lpr Mice
Published on: June 8, 2022
Microvascular C5b-9 deposition in non-lesional skin in patients with SLE and its correlation with active lupus
Meghan Anderson1, Cynthia Magro2, H Michael Belmont3
1Department of Rheumatology, NYU Grossman School of Medicine, New York City, New York, USA meghan.anderson@pennmedicine.upenn.edu.
Objective:
Tissue damage in lupus nephritis (LN) is mediated by activation of the classical complement pathway. Complement-mediated upregulation of endothelial cell adhesion molecules is seen in dermal blood vessels of non-lesional skin of patients with active lupus. In diseases with systemic complement activation, extensive microvascular C5b-9 deposition is seen in non-lesional skin. In this study, we assess the presence of systemic complement pathway activation as determined by non-lesional skin microvascular C5b-9 deposition in patients with LN.
Methods:
Eight patients with active LN and eight patients without active LN underwent non-lesional skin biopsies. Using a diaminobenzidine technique, specimens were evaluated for microvascular C5b-9 consistent with systemic complement pathway activation.
Results:
Five of eight patients with active LN and one of eight patients without active LN demonstrated positive C5b-9 staining in non-lesional skin (p=0.04). Positive non-lesional C5b-9 staining has greater specificity, 87.5%, for active LN than pyuria, low complements, elevated double-stranded DNA (dsDNA) and proteinuria. Urine protein creatinine ratio was significantly higher in patients with positive non-lesional C5b-9 deposition (5.18 vs 1.20; p=0.04). C5b-9 deposition was not associated with a higher NIH Activity Index, interstitial fibrosis, dsDNA or lower complements.
Conclusion:
This is the first study to demonstrate evidence in non-lesional skin of microvascular C5b-9 indicative of systemic complement pathway activation in LN. C5b-9 deposition is statistically more common and demonstrated greater specificity than most historical biomarkers for active LN. The findings support a potential role for microvascular C5b-9 assessment in non-lesional skin as a biomarker for LN activity.
