HIV-1 decreases Nrf2/ARE activity and phagocytic function in alveolar macrophages

Respiratory complications occur frequently in individuals living with human immunodeficiency-1 virus (HIV) infection, and there is evidence that HIV-related oxidative stress impairs alveolar macrophage immune function. We hypothesized that nuclear factor (erythroid-derived 2)-like 2 (Nrf2), a master transcription factor that activates the antioxidant response element (ARE) and regulates antioxidant defenses, has an important role in alveolar macrophage (AMs) immune dysfunction in individuals with HIV infections. To test that hypothesis, we analyzed human monocyte-derived macrophages (MDMs) that were either infected with HIV-1 or were exposed to the HIV-related proteins gp120 and Tat ex vivo and determined that either stress affected the expression of Nrf2 and the Nrf2-ARE-dependent genes for NAD(P)H dehydrogenase, quinone 1 (NQO1) and glutamate-cysteine ligase, catalytic subunit (GCLC). We then determined that the expression of Nrf2, NQO1, and GCLC was significantly decreased in primary AMs isolated from HIV-1 transgenic rats. In parallel, treating a rat macrophage cell line (NR8383 cells) with the HIV-related proteins gp120 or Tat similarly decreased the gene and protein expression of Nrf2, NQO1, and GCLC. Further, phagocytic function was decreased in both human MDMs infected with HIV-1 and primary AMs from HIV-1 transgenic rats. Importantly, treating HIV-1-infected human MDMs or AMs from HIV-1 transgenic rats with sulforaphane (SFN, an Nrf2 activator) significantly improved their phagocytic function. The salutary effects of SFN were abrogated by silencing RNA to Nrf2 in wild-type rat macrophages. Our findings demonstrate that HIV-1 infection and exposure to HIV-1-related proteins inhibit Nrf2-ARE activity in the AMs and impair their phagocytic function. Treatments targeted at increasing Nrf2-ARE activity could, therefore, enhance lung innate immunity in people living with HIV-1.