Chronic Morphine Administration Differentially Modulates Viral Reservoirs in a Simian Immunodeficiency Virus SIVmac251-Infected Rhesus Macaque Model

Abstract

HIV persists in cellular reservoirs despite effective combined antiretroviral therapy (cART) and there is viremia flare up upon therapy interruption. Opioids modulate the immune system and suppress antiviral gene responses, which significantly impact people living with HIV (PLWH). However, the effect of opioids on viral reservoir dynamics remain elusive. Herein, we developed a morphine dependent SIVmac251 infected Rhesus macaque (RM) model to study the impact of opioids on HIV reservoirs. RMs on a morphine (or saline control) regimen were infected with SIVmac251. The cART was initiated in approximately half the animals five weeks post-infection, and morphine/saline administration continued until the end of the study. Among the untreated RM, we did not find any difference in plasma/CSF or in cell-associated DNA/RNA viral load in anatomical tissues. On the other hand, within the cART suppressed macaques, there was a reduction in cell-associated DNA load, intact proviral DNA levels, and in inducible SIV reservoir in lymph nodes (LNs) of morphine administered RMs. In distinction to LNs, in the CNS, the size of latent SIV reservoirs was higher in the CD11b+ microglia/macrophages in morphine dependent RMs. These results suggest that in the proposed model, morphine plays a differential role in SIV reservoirs by reducing the CD4+ T-cell reservoir in lymphoid tissues, while increasing the microglia/reservoir size in CNS tissue. The findings from this pre-clinical model will serve as a tool for screening therapeutic strategies to reduce/eliminate HIV reservoirs in opioid dependent PLWH. IMPORTANCE Identification and clearance of HIV reservoirs is a major challenge in achieving a cure for HIV. This is further complicated by co-morbidities that may alter the size of the reservoirs. There is an overlap between the risk factors for HIV and opioid abuse. Opiates have been recognized as prominent co-morbidities in HIV-infected populations. People infected with HIV also abusing opioids have immune modulatory effects and more severe neurological disease. However, the impact of opioid abuse on HIV reservoirs remains unclear. In this study, we used morphine dependent SIVmac251 infected rhesus macaque (RM) model to study the impact of opioids on HIV reservoirs. Our studies suggested that people with HIV who abuse opioids had higher reservoirs in CNS than the lymphoid system. Extrapolating the macaque findings in humans suggests that such differential modulation of HIV reservoirs among people living with HIV abusing opioids could be considered for future HIV cure research efforts.

Diminished Peripheral CD29hi Cytotoxic CD4+ T Cells Are Associated With Deleterious Effects During SIV Infection

“…However, no subsequent cART was administered. All animal characteristics and treatment regimen details were previously described ( 10 ). The experimental schema utilized for the study included a total of 19 rhesus macaques.…”

“…Briefly, RNA was extracted from EDTA plasma using a QIA amp viral RNA mini kit (Qiagen, Germantown, MD, USA; Cat no: 52906). Additional information on primers and probes with details of PCR conditions were described previously ( 10 ).…”

“…SIV RNA measures were then performed using qRT-PCR. Levels of replication-competent viruses were denoted as infectious units per million (IUPM) and were estimated using the IUPMStats v1.0 infection frequency calculator ( 10 , 51 ).…”

“…Although great strides have been undertaken, the cellular responses associated with sustaining persistence versus viral eradication remain poorly understood (3)(4)(5). HIV-infected individuals worldwide live different lifestyles stemming from varied cultural and sexual practices, co-exposures to other pathogens, and comorbid substance abuse not limited to the illicit use of drugs like morphine, cocaine, and heroin (6)(7)(8)(9)(10)(11). Collectively, these behaviors differentially impact the body's immune response, alter disease pathogenesis and need to be considered during the development of a universal HIV cure (6,12).…”

The Contributions of Clinical Pharmacology to HIV Cure Research

“…9 In addition to CD4+ T cells, the myeloid lineage of cells, including microglia and perivascular macrophages in the brain and urethral tissue macrophages, also serve as viral reservoirs. 10 These same anatomic sites may also be pharmacologic sanctuaries, as evidenced by concentrations of antiretroviral (ARV) drugs lower than those in peripheral blood and, in some cases, associated with evidence for low-level ongoing virus replication. 11,12 Following HIV entry into susceptible host cells, a cDNA copy of viral RNA is integrated into the infected cell's chromosome.…”