Alcohol, Anti-HIV Drugs, and/or Hippuric Acid Deteriorate Cellular Stresses in Senescent Hepatocytes and Aging Murine Liver

Liver disease has increased recently in aging people living with HIV and substance use disorders, and little is known about injurious effects of anti-HIV drugs, alcohol and other substances on cellular stress responses in senescent hepatocytes and aging liver. In this study, senescence of two liver cell lines: HepG2 and AML-12, was induced by hydrogen peroxide (H₂O₂) and confirmed by senescence makers including cyclin-dependent kinase inhibitor CKI (p21), senescence-associated β-galactosidase (SA-β-gal), or insulin-like growth factor 1 (IGF1). The cell and mouse models (2-month-old versus 23-month-old) were treated with ritonavir, lopinavir, ethanol, or cocaine derivative hippuric acid. Cell stress responses and stress-related metabolic proteins were evaluated. In non-senescent cells, treatments of alcohol, ritonavir and lopinavir alone or in combinations increased expression of endoplasmic reticulum stress related glucose-regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP), had minor effects on glucose-regulated protein 75 (GRP75) and inositol 1,4,5-trisphosphate (IP3) receptor type 2 (IP3R2), ubiquitin specific protein 10 (USP10), USP17, USP20, lipogenic factor peroxisome proliferator-activated receptor gamma (PPARγ), Ras-related protein Rab-18 (RAB18), or Ras converting enzyme 1(RCE1). In the senescent cells, alcohol, ritonavir, lopinavir, and/or hippuric acid induced higher expression of GRP78, CHOP, IP3R2, USP17, USP20, PPARγ and RAB18, but reduced expression of GRP75, USP10, and RCE1. In the aged mice fed alcohol diet and the anti-HIV drugs, hepatic GRP78, CHOP, USP17, PPARγ, and triglycerides, number of senescent or dead hepatocytes, blood levels of alanine aminotransferase were significantly increased and RCE1 was reduced compared to young mice fed alcohol and the drugs. These results suggest that protein factors and responses that potentially function in ameliorating cellular stresses are undermined and protein factors that might cause cell dysfunctions or injury are exacerbated in the senescent hepatocytes and liver of aged mice treated with alcohol and anti-HIV drugs.