SIV Infection and the HIV Proteins Tat and Nef Induce Senescence in Adipose Tissue and Human Adipose Stem Cells, Resulting in Adipocyte Dysfunction

Abstract

Background: Aging is characterized by adipose tissue senescence, inflammation, and fibrosis, with trunk fat accumulation. Aging HIV-infected patients have a higher risk of trunk fat accumulation than uninfected individuals—suggesting that viral infection has a role in adipose tissue aging. We previously demonstrated that HIV/SIV infection and the Tat and Nef viral proteins were responsible for adipose tissue fibrosis and impaired adipogenesis. We hypothesized that SIV/HIV infection and viral proteins could induce adipose tissue senescence and thus lead to adipocyte dysfunctions. Methods: Features of tissue senescence were evaluated in subcutaneous and visceral adipose tissues of SIV-infected macaques and in human adipose stem cells (ASCs) exposed to Tat or Nef for up to 30 days. Results: p16 expression and p53 activation were higher in adipose tissue of SIV-infected macaques than in control macaques, indicating adipose tissue senescence. Tat and Nef induced higher senescence in ASCs, characterized by higher levels of senescence-associated beta-galactosidase activity, p16 expression, and p53 activation vs. control cells. Treatment with Tat and Nef also induced oxidative stress and mitochondrial dysfunction. Prevention of oxidative stress (using N-acetyl-cysteine) reduced senescence in ASCs. Adipocytes having differentiated from Nef-treated ASCs displayed alterations in adipogenesis with lower levels of triglyceride accumulation and adipocyte marker expression and secretion, and insulin resistance. Conclusion: HIV/SIV promotes adipose tissue senescence, which in turn may alter adipocyte function and contribute to insulin resistance.

Keywords

• adipose stem cells
• HIV
• senescence
• oxidative stress
• adipogenesis