Class IV-S versus class IV-G lupus nephritis: clinical and morphologic differences suggesting different pathogenesis

Area of Science:

• Nephrology
• Immunology
• Pathology

Background:

• Lupus nephritis class IV is reclassified into segmental (IV-S) and global (IV-G) proliferative lesions.
• This study investigates the validity and pathogenic differences between these two lupus nephritis subtypes.

Purpose of the Study:

• To explore the clinical and morphological distinctions between lupus nephritis class IV-S and IV-G.
• To investigate potential differences in the pathogenesis of lupus nephritis IV-S and IV-G lesions.

Main Methods:

• Reclassification of lupus nephritis patients based on the proposed IV-S and IV-G criteria.
• Analysis of clinical data, biopsy findings (light microscopy and immunofluorescence), and long-term survival.
• Comparison of pathological features including immune deposits, fibrinoid necrosis, and cellular infiltration.

Main Results:

• Class IV-G lesions were associated with worse proteinuria, lower hemoglobin, lower CH50, and higher serum creatinine.
• Class IV-G showed greater immune deposits and subendothelial deposits, while IV-S had more mesangial deposits and fibrinoid necrosis.
• Class IV-G involved more glomeruli and had more monocytes/macrophages; long-term survival was poorer for IV-G with persistent lesions.

Conclusions:

• Significant clinical and morphological differences exist between lupus nephritis class IV-S and IV-G.
• Class IV-G lesions appear to represent a more traditional immune complex-mediated disease.
• Class IV-S lesions, with prominent fibrinoid necrosis and less correlation with immune deposits, suggest a distinct pathogenic pathway.