Chronic Δ9-Tetrahydrocannabinol Administration May Not Attenuate Simian Immunodeficiency Virus Disease Progression in Female Rhesus Macaques

Persons living with HIV/AIDS (PLWHA) frequently use cannabinoids, either recreationally by smoking marijuana or therapeutically (delta-9-tetrahydrocannabinol; (9)-THC dronabinol). Previously, we demonstrated that chronic (9)-THC administration decreases early mortality in male simian immunodeficiency virus (SIV)-infected macaques. In this study, we sought to examine whether similar protective effects resulted from chronic cannabinoid administration in SIV-infected female rhesus macaques. Clinical and viral parameters were evaluated in eight female rhesus macaques that received either (9)-THC (0.18-0.32mg/kg, intramuscularly, twice daily) or vehicle (VEH) starting 28 days prior to intravenous inoculation with SIVmac251. SIV disease progression was assessed by changes in body weight, mortality, viral levels in plasma and mucosal sites, and lymphocyte subsets. In contrast to our results in male animals, chronic (9)-THC did not protect SIV-infected female rhesus macaques from early mortality. Markers of SIV disease, including viral load and CD4(+)/CD8(+) ratio, were not altered by (9)-THC compared to control females; however, females that received chronic (9)-THC did not gain as much weight as control animals. In addition, (9)-THC administration increased total CXCR4 expression in both peripheral and duodenal CD4(+) and CD8(+) T lymphocytes prior to SIV inoculation. Although protection from early mortality was not evident, chronic (9)-THC did not affect clinical markers of SIV disease progression. The contrasting effects of chronic (9)-THC in males versus females remain to be explained, but highlight the need for further studies to explore the sex-dependent effects of (9)-THC and other cannabinoids on the HIV disease course and their implications for virus transmission.