Effect of lymphokines on 35sulfate uptake by the glomerular basement membrane

Area of Science:

• Nephrology
• Immunology
• Molecular Biology

Background:

• Idiopathic minimal-lesion nephrotic syndrome (MLNS) is characterized by proteinuria without significant glomerular abnormalities.
• Previous studies indicated lymphocytes from MLNS patients produce a lymphokine that enhances glomerular basement membrane (GBM) 35Sulfate uptake.

Purpose of the Study:

• To identify the specific lymphokine responsible for increased GBM 35Sulfate uptake in MLNS.
• To investigate the effects of various cytokines, including interleukins (IL) 2-4, 6, and 8, on GBM 35Sulfate incorporation in vitro.

Main Methods:

• Culture of rat glomeruli with various cytokines (IL-2-4, 6, 8, GM-CSF, TNF).
• Measurement of 35Sulfate incorporation into the GBM.
• Detection of IL-8 in supernatants from MLNS patient cell cultures.
• Inhibition studies using anti-IL-8 neutralizing antibodies.

Main Results:

• Interleukin-8 (IL-8) significantly increased GBM 35Sulfate uptake compared to controls (10.8 vs. 7.9 cpm/μg GBM protein, p < 0.005).
• IL-8 reproduced the effect of the previously identified supernatant factor.
• IL-8 was detected in supernatants from MLNS patient cultures during relapse.
• Anti-IL-8 antibodies abolished the GBM 35Sulfate uptake enhancement by the supernatant factor.

Conclusions:

• Interleukin-8 (IL-8) is identified as the specific lymphokine responsible for increased GBM 35Sulfate uptake in idiopathic minimal-lesion nephrotic syndrome.
• IL-8 plays a significant role in the pathogenesis of MLNS by affecting GBM composition.
• Targeting IL-8 may offer a therapeutic strategy for MLNS.