Latent TGF-beta1 protects against crescentic glomerulonephritis

Area of Science:

• Nephrology
• Immunology
• Cell Biology

Background:

• Transforming growth factor-beta (TGF-beta) is crucial in renal fibrosis.
• Previous studies showed latent TGF-beta1 overexpression in skin did not impair renal function.
• The protective role of latent TGF-beta1 in immune-mediated kidney diseases remained unclear.

Purpose of the Study:

• To investigate the effect of latent TGF-beta1 overexpression in skin on anti-GBM crescentic glomerulonephritis.
• To determine if latent TGF-beta1 can protect against immune-mediated renal inflammation and fibrosis.

Main Methods:

• Induced anti-GBM disease in wild-type and transgenic mice overexpressing latent TGF-beta1 in keratinocytes.
• Assessed renal histology, function, proteinuria, immune cell infiltration, inflammatory markers, and fibrosis markers.
• Measured plasma and renal tissue levels of latent and active TGF-beta1, and analyzed Smad7, NF-kappaB, and TGF-beta/Smad2/3 activation.

Main Results:

• Transgenic mice showed reduced proteinuria (50%), preserved renal function, and suppressed crescent formation (70%).
• Transgenic mice exhibited decreased renal inflammation with 70% fewer T cells and macrophages, and 70-80% lower IL-1beta, TNFalpha, and MCP-1 expression.
• Progressive renal fibrosis was prevented in transgenic mice, associated with elevated latent TGF-beta1, upregulated Smad7, and suppressed NF-kappaB and TGF-beta/Smad2/3 activation.

Conclusions:

• Overexpression of latent TGF-beta1 in skin confers significant protection against anti-GBM crescentic glomerulonephritis.
• Protection is likely mediated by Smad7-dependent inhibition of NF-kappaB-driven renal inflammation and TGF-beta/Smad2/3-driven fibrosis.
• Latent TGF-beta1 may represent a potential therapeutic target for immune-mediated kidney diseases.