HIV-infected apoptotic hepatocytes program macrophages for inflammasome development: role of alcohol

Abstract

Abstract Liver injury is a second cause of non-AIDS mortality in HIV-infection, and the progression to end-stage liver disease is more rapid in alcohol abusers. Hepatocytes comprise 80% of liver cells and are strong ethanol metabolizers. To elucidate whether hepatocytes are HIV-infected, we measured the kinetics of HIVgag RNA (RT-PCR) and p24 (Western blot) expression in Huh7.5-CYP (hepatocyte-like cells) exposed to HIV-1ADA in the presence or absence of acetaldehyde-generation system (AGS). The measurements were done at days 1, 3 and 5 post-infection. We found that the highest levels of HIV markers were observed at day 1, with further decrease by day 3 and 5. AGS treatment substantially increased these levels. The accumulation of HIV in hepatocytes was accompanied by activation of oxidative stress, judged by increasing reactive oxygen species (ROS) production at day 3 and 5 post-infection and enhanced expression of 4-hydroxynonenal (4HNE) protein adducts, which increased caspase 3 cleavage. To mimic proapoptotic effect of acetaldehyde and study the involvement of apoptotic hepatocytes in liver inflammation, we incubated apoptotic HIV-infected or uninfected Huh7.5-CYP cells with monocyte-derived human macrophages (MDMs) and then measured inflammasome activation based on NLRP3, caspase 1, IL-1β and IL-18 mRNAs. Activation of inflammasome in MDMs was more prominent when HIV-infected apoptotic cells were engulfed by MDM compared with uninfected cell engulfment. We conclude that acetaldehyde synergies with HIV to induce oxidative stress and apoptosis in hepatocytes. The engulfment of apoptotic HIV+ hepatocytes leads to inflammasome activation in macrophages, thereby promoting progression to liver injury.