Altered expression pattern of Nrf2/HO-1 axis during accelerated-senescence in HIV-1 transgenic rat

Chronic oxidative stress plays a central role in the pathogenesis of many diseases, including HIV-1 associated disorders. Concomitantly with the decline of endogenous antioxidant systems, it was reported that HIV-1-related proteins increase the production of radical species in cells and tissues that are not directly infected by the virus. In the context of HIV-1 infection, the role of Nrf2, a key transcription factor that contributes to the maintenance of cellular redox homeostasis, remains largely uncharacterized. One of the major stress-responsive player regulated by Nrf2 is the antioxidant enzyme HO-1. The Nrf2/HO-1 axis constitutes a crucial cell survival mechanism to counteract oxidative stress and inflammation. The present study aims to investigate the age-related patterns of Nrf2 and HO-1 in different brain regions and tissues of HIV-1 transgenic rat. Since HIV-1 induces an accelerated aging and the redox imbalance may actively promote senescence, we also evaluated the senescence phenotype-switching by quantifying levels of β-galactosidase activity. Our results showed changes in gene expression, with different trends depending on the brain regions and tissues examined. However, compared to age-matched controls, we observed in HIV-1 transgenic rats a significant reduction in the protein levels of Nrf2 and HO-1, suggesting a weakening in the protection exerted by Nrf2/HO-1 system. Moreover, we show that senescence occurs more rapidly in HIV-1 transgenic rats than in control animals. To our knowledge this is the first in vivo report showing the involvement of Nrf2/HO-1 pathway in a rat model of HIV-1.