HIV-1 upregulates VEGF in podocytes

Area of Science:

• Nephrology
• Virology
• Molecular Biology

Background:

• HIV-associated nephropathy (HIVAN) presents as collapsing focal segmental glomerulosclerosis (FSGS).
• Transgenic mice overexpressing vascular endothelial growth factor 164 (VEGF164) in podocytes develop collapsing FSGS.
• The role of VEGF in HIVAN pathogenesis requires elucidation.

Purpose of the Study:

• To investigate the role of VEGF in the development of HIVAN.
• To determine if HIV-1 infection upregulates VEGF expression in podocytes.
• To explore the mechanisms by which HIV-1 influences VEGF and related pathways in podocytes.

Main Methods:

• Immunohistochemistry on kidneys from HIV-1-transgenic mice (Tg26) and HIVAN patients.
• Analysis of VEGF and hypoxia-inducible factor 2alpha (HIF-2alpha) mRNA and protein levels in HIV-infected podocytes in vitro.
• Investigation of HIV viral protein Nef's effect on VEGF and HIF-2alpha expression.
• Assessment of VEGFR2, neuropilin-1, and semaphorin 3a expression.
• In vitro experiments using exogenous VEGF and VEGFR2 neutralizing antibodies on podocytes.

Main Results:

• Kidneys from Tg26 mice and HIVAN patients showed increased VEGF and HIF-2alpha expression compared to controls.
• HIV-infected podocytes exhibited elevated VEGF and HIF-2alpha mRNA and protein levels.
• HIV-1 viral protein Nef stimulated VEGF and HIF-2alpha transcription via Src kinase and Stat3.
• HIV-1 upregulated VEGFR2 and neuropilin-1 while suppressing semaphorin 3a in podocytes.
• Exogenous VEGF promoted podocyte proliferation and de-differentiation; VEGFR2 blockade reversed these effects in HIV-infected or Tg26-derived podocytes.

Conclusions:

• HIV-1 infection induces VEGF and VEGFR2 expression in podocytes.
• VEGF signaling in podocytes is a critical factor in the pathogenesis of HIVAN.
• Targeting the VEGF pathway may offer therapeutic potential for HIVAN.