Endogenous opioid peptides suppress cytokine-mediated upregulation of HIV-1 expression in the chronically infected promonocyte clone U1

Opioid and neuroHIV Comorbidity - Current and Future Perspectives

With the current national opioid crisis, it is critical to examine the mechanisms underlying pathophysiologic interactions between human immunodeficiency virus (HIV) and opioids in the central nervous system (CNS). Recent advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal opioid-HIV interactions with increasing clarity. However, despite the substantial new insight, the unique impact of opioids on the severity, progression, and prognosis of neuroHIV and HIV-associated neurocognitive disorders (HAND) are not fully understood. In this review, we explore, in detail, what is currently known about mechanisms underlying opioid interactions with HIV, with emphasis on individual HIV-1-expressed gene products at the molecular, cellular and systems levels. Furthermore, we review preclinical and clinical studies with a focus on key considerations when addressing questions of whether opioid-HIV interactive pathogenesis results in unique structural or functional deficits not seen with either disease alone. These considerations include, understanding the combined consequences of HIV-1 genetic variants, host variants, and μ-opioid receptor (MOR) and HIV chemokine co-receptor interactions on the comorbidity. Lastly, we present topics that need to be considered in the future to better understand the unique contributions of opioids to the pathophysiology of neuroHIV. Graphical Abstract Blood-brain barrier and the neurovascular unit. With HIV and opiate co-exposure (represented below the dotted line), there is breakdown of tight junction proteins and increased leakage of paracellular compounds into the brain. Despite this, opiate exposure selectively increases the expression of some efflux transporters, thereby restricting brain penetration of specific drugs.

Synthetic Opioid Use and Common Injection-associated Viruses: Expanding the Translational Research Agenda

The US is in the midst of a major epidemic of opioid addiction and related comorbidities. People with opioid use disorder (OUD) are at significant risk for transmission of several blood-borne pathogens including the human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV). Commonly abused opioids and their receptors promote viral replication and virus-mediated pathology. However, most studies demonstrating an adverse effect of drugs of abuse have been conducted in vitro, the specific effects of synthetic opioids on viral replication have been poorly characterized, and the evaluation of opioid-virus interactions in clinically relevant populations is rare. Rigorous characterization of the interactions among synthetic opioids, host cells, and common injection-associated viral infections will require an interdisciplinary research approach and translational studies conducted on humans. Such research promises to improve clinical management paradigms for difficult-to-treat populations, facilitate rational public health policies given severely strained resources, and reveal additional pathways for novel target-specific therapeutic interventions. This mini-review examines the published literature on the effects of opioids on HIV, HBV, and HCV pathogenesis and proposes a series of scientific questions and considerations to establish a translational research agenda focused on opioid-virus interactions.

Opioids and Viral Infections: A Double-Edged Sword

Opioids and their receptors have received remarkable attention because they have the ability to alter immune function, which affects disease progression. In vitro and in vivo findings as well as observations in humans indicate that opioids and their receptors positively or negatively affect viral replication and virus-mediated pathology. The present study reviews recent insights in the role of opioids and their receptors in viral infections and discusses possible therapeutic opportunities. This review supports the emerging concept that opioids and their receptors have both favorable and unfavorable effects on viral disease, depending on the type of virus. Targeting of the opioid system is a potential option for developing effective therapies; however caution is required in relation to the beneficial functions of opioid systems.

Heroin inhibits HIV-restriction miRNAs and enhances HIV infection of macrophages

Although opioids have been extensively studied for their impact on the immune system, limited information is available about the specific actions of opioids on intracellular antiviral innate immunity against HIV infection. Thus, we investigated whether heroin, one of the most abused drugs, inhibits the expression of intracellular HIV restriction microRNA (miRNA) and facilitates HIV replication in macrophages. Heroin treatment of macrophages enhanced HIV replication, which was associated with the downregulation of several HIV restriction miRNAs. These heroin-mediated actions on the miRNAs and HIV could be antagonized by naltrexone, an opioid receptor antagonist. Furthermore, the in vitro negative impact of heroin on HIV-associated miRNAs was confirmed by the in vivo observation that heroin addicts had significantly lower levels of macrophage-derived HIV restriction miRNAs than those in the control subjects. These in vitro and in vivo findings indicate that heroin use compromises intracellular anti-HIV innate immunity, providing a favorable microenvironment for HIV survival in the target cells.

Morphine modulates monocyte-macrophage conversion phase

Monocyte migration and their activation into the macrophage phenotype play a role in the modulation of tissue injury. We studied the effect of morphine on the monocyte-macrophage conversion phase (MMCP). Phorbol 12-myristate 13-acetate (PMA) activated THP-1 cells and promoted their adhesion to the substrate. Morphine inhibited PMA-induced MMCP. However, opiate receptor antagonists attenuated this effect of morphine. Interestingly, PMA as well as morphine-stimulated superoxide production by monocytes. Superoxide dismutase (SOD) not only inhibited PMA-mediated MMCP but also attenuated the inhibitory effect of morphine. PMA not only enhanced adhesion of monocytes to a filter but also promoted their migration. These findings suggest that the PMA-induced macrophage phenotype conversion may be accelerating their migration; whereas, morphine may be preventing the migration of monocytes by inhibiting MMCP.

Opioids as modulators of cell death and survival--unraveling mechanisms and revealing new indications

Opioids are powerful analgesics but also drugs of abuse. Because opioid addicts are susceptible to certain infections, opioids have been suspected to suppress the immune response. This was supported by the finding that various immune-competent cells express opioid receptors and undergo apoptosis when treated with opioid alkaloids. Recent evidence suggests that opioids may also effect neuronal survival and proliferation or migrating properties of tumor cells. A multitude of signaling pathways has been suggested to be involved in these extra-analgesic effects of opioids. Growth-promoting effects were found to be mediated through Akt and Erk signaling cascades. Death-promoting effects have been ascribed to inhibition of nuclear factor-kappaB, increase of Fas expression, p53 stabilization, cytokine and chemokine release, and activation of nitric oxide synthase, p38, and c-Jun-N-terminal kinase. Some of the observed effects were inhibited with opioid receptor antagonists or pertussis toxin; others were unaffected. It is still unclear whether these properties are mediated through typical opioid receptor activation and inhibitory G-protein-signaling. The present review tries to unravel controversial findings and provides a hypothesis that may help to integrate diverse results.

Reduction of lipopolysaccharide-induced neurotoxicity in mouse mixed cortical neuron/glia cultures by ultralow concentrations of dynorphins

Previously we reported that ultralow concentrations of dynorphins (10(-16) to 10(-12) M) inhibited lipopolysaccharide (LPS)-induced production of nitric oxide (NO) and proinflammatory cytokines in mouse glia without the participation of kappa-opioid receptors. In the current study using mouse cortical neuron-glia cocultures, we examined the possibility that inhibition of glia inflammatory response by dynorphins might be neuroprotective for neurons. LPS, in a concentration-dependent manner, markedly increased the release of lactate dehydrogenase (LDH), an indicator of cellular injury. Ultralow concentrations (10(-14) to 10(-12) M) of dynorphin (dyn) A-(1-8) significantly prevented the LPS-induced release of LDH, loss of neurons, and changes in cell morphology, in addition to inhibition of LPS-induced nitrite production. Meanwhile, ultralow concentrations (10(-15) to 10(-13) M) of des-[Tyr(1)]-dyn A-(2-17), a nonopioid peptide which does not bind to kappa-opioid receptors, exhibited the same inhibitory effect as dyn A-(1-17). These results suggest that dynorphins at ultralow concentrations are capable of reducing LPS-induced neuronal injury and these neuroprotective effects of dynorphins are not mediated by classical opioid receptors.

Renal cell cytokine production stimulates HIV-1 expression in chronically HIV-1-infected monocytes

Renal infiltration of human immunodeficiency virus type 1 (HIV-1)-infected monocytes might play an important role in the development of HIV-associated nephropathy (HIVAN). In the present study, we investigated the effects of cytokines produced by cultured human mesangial cells (HMC) and proximal tubular epithelial cells (PTEC) on HIV-1 expression in chronically HIV-1-infected promonocytes (U1 cells). Human mesangial cells constitutively secreted interleukin-6 (IL-6) but not tumor necrosis factor-alpha (TNF-alpha) into the culture medium, whereas PTEC constitutively secreted both IL-6 and TNF-alpha. Coculture of U1 cells with HMC or PTEC for 72 hours markedly stimulated HIV-1 expression, with the p24 antigen concentration in the coculture supernatants ranging from approximately 200 to 1850 pg/ml. The presence of anti-IL-6 antibody in the coculture medium nearly completely blocked HIV-1 expression in the HMC/U1 cell cocultures (P < 0.05). Anti-IL-6 antibody and anti-TNF-alpha antibody blocked HIV-1 expression in the PTEC/U1 cell cocultures by 40% and 53%, respectively (P < 0.05). Moreover, the combination of anti-IL-6 and anti-TNF-alpha antibodies additively reduced coculture HIV-1 expression by 87% (P < 0.05). We conclude that renal cell production of IL-6 and TNF-alpha might provide a potent stimulus for HIV-1 expression in HIV-1-infected monocytes that infiltrate the kidney, and that this may play an important role in the pathogenesis of HIVAN.