Up-regulation of soluble tumor necrosis factor receptor two in plasma of HIV-seropositive individuals who use opiates

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

Opioids and Opioid Maintenance Therapies: Their Impact on Monocyte-Mediated HIV Neuropathogenesis

BACKGROUND

HIV-1 enters the CNS within two weeks after peripheral infection and results in chronic neuroinflammation that leads to HIV associated neurocognitive disorders (HAND) in more than 50% of infected people. HIV enters the CNS by transmigration of infected monocytes across the blood brain barrier. Intravenous drug abuse is a major risk factor for HIV-1 infection, and opioids have been shown to alter the progression and severity of HAND. Methadone and buprenorphine are opioid derivates that are used as opioid maintenance therapies. They are commonly used to treat opioid dependency in HIV infected substance abusers, but their effects on monocyte migration relevant to the development of cognitive impairment are not well characterized.

CONCLUSION

Here, we will discuss the effects of opioids and opioid maintenance therapies on the inflammatory functions of monocytes and macrophages that are related to the development of neuroinflammation in the context of HIV infection.

Associations of Circulating Soluble Tumor Necrosis Factor-α Receptors 1 and 2 with Interleukin-6 Levels in an Aging Cohort of Injection Drug Users with or at High Risk for HIV Infection

Chronic inflammation marked by elevated interleukin (IL)-6, soluble tumor necrosis factor (TNF)-α receptor (sTNFR)-1, and sTNFR-2 levels may play a detrimental role in aging and HIV infection. This study aimed to evaluate the relationships of circulating IL-6 with sTNFR-1 and sTNFR-2 levels in an aging cohort of injection drug users (IDUs) with or at high risk for HIV infection. The AIDS Linked to the Intravenous Experience (ALIVE) study is a community-recruited, prospective observational study of former and current IDUs in Baltimore, Maryland. Serum IL-6, sTNFR-1, and sTNFR-2 levels were measured using standard ELISA. Multivariate linear regression analysis was employed, adjusting for age, sex, HIV status, injection drug use, comorbidities, as well as HIV viral load, CD4 T cell counts, and antiretroviral therapy where appropriate. The analysis included 1,178 participants (316 HIV positive and 862 HIV negative). In the adjusted model, sTNFR-1 and sTNFR-2 were individually associated with IL-6 (regression coefficient: 0.877 and 0.556, respectively, for all participants; 0.607 and 0.407 for HIV positives; and 0.999 and 0.628 for HIV negatives, all p < 0.0001). In the model combining sTNFR-1 and sTNFR-2, the associations for sTNFR-1 remained significant (0.693 for all participants, p < 0.0001; 0.417 for HIV positives, p < 0.05; and 0.840 for HIV negatives), while those for sTNFR-2 were no longer significant. sTNFR-1 and sTNFR-2 were positively associated with IL-6 in ALIVE participants. These findings provide initial insight into the in vivo relationship between TNF-α activation and IL-6 and a basis for further investigations into potential mechanisms underlying chronic inflammation in aging and HIV infection.

Tight junction regulation by morphine and HIV-1 tat modulates blood-brain barrier permeability

Human immunodeficiency virus (HIV)-1 patients who abuse opiates are at a greater risk of developing neurological complications of AIDS. Alterations in blood-brain barrier (BBB) integrity are associated with cytoskeletal disorganization and disruption of tight junction (TJ) integrity. We hypothesize that opiates in combination with HIV-1 viral proteins can modulate TJ expression in primary brain microvascular endothelial cells (BMVEC), thereby compromising BBB integrity and exacerbating HIV-1 neuropathogenesis. We investigated the effect of morphine and/or tat on the expression of TJ proteins ZO-1, JAM-2, Occludin and P-glycoprotein and the functional effects of TJ modulation in BMVEC. Morphine and/or tat, via the activation of pro-inflammatory cytokines, intracellular Ca(2+) release, and activation of myosin light chain kinase, modulated TJ expression resulting in decreased transendothelial electric resistance and enhanced transendothelial migration across the BBB. These studies may lead to the development of novel anti-HIV-1 therapeutics that target specific TJ proteins, thus preventing TJ disruption in opiate using HIV-1 patients.

Hepatitis infection in the treatment of opioid dependence and abuse

Many new and existing cases of viral hepatitis infections are related to injection drug use. Transmission of these infections can result directly from the use of injection equipment that is contaminated with blood containing the hepatitis B or C virus or through sexual contact with an infected individual. In the latter case, drug use can indirectly contribute to hepatitis transmission through the dis-inhibited at-risk behavior, that is, unprotected sex with an infected partner. Individuals who inject drugs are at-risk for infection from different hepatitis viruses, hepatitis A, B, or C. Those with chronic hepatitis B virus infection also face additional risk should they become co-infected with hepatitis D virus. Protection from the transmission of hepatitis viruses A and B is best achieved by vaccination. For those with a history of or who currently inject drugs, the medical management of viral hepatitis infection comprising screening, testing, counseling and providing care and treatment is evolving. Components of the medical management of hepatitis infection, for persons considering, initiating, or receiving pharmacologic therapy for opioid addiction include: testing for hepatitis B and C infections; education and counseling regarding at-risk behavior and hepatitis transmission, acute and chronic hepatitis infection, liver disease and its care and treatment; vaccination against hepatitis A and B infection; and integrative primary care as part of the comprehensive treatment approach for recovery from opioid abuse and dependence. In addition, participation in a peer support group as part of integrated medical care enhances treatment outcomes. Liver disease is highly prevalent in patient populations seeking recovery from opioid addiction or who are currently receiving pharmacotherapy for opioid addiction. Pharmacotherapy for opioid addiction is not a contraindication to evaluation, care, or treatment of liver disease due to hepatitis virus infection. Successful pharmacotherapy for opioid addiction stabilizes patients and improves patient compliance to care and treatment regimens as well as promotes good patient outcomes. Implementation and integration of effective hepatitis prevention programs, care programs, and treatment regimens in concert with the pharmacological therapy of opioid addiction can reduce the public health burdens of hepatitis and injection drug use.

Serum soluble TNF receptor I and II levels correlate with disease activity in IBD patients

BACKGROUND

Tumor necrosis factor alpha (TNFalpha) is a proinflammatory cytokine and an important mediator in the pathophysiology of inflammatory bowel disease (IBD). The effects of TNFalpha are mediated by 2 specific receptors, a 55-kDa protein (TNF-RI) and a 75-kDa receptor (TNF-RII), which are usually bound to the cell surface. Soluble TNF receptors I and II (sTNF-RI + II) are released by proteolytic cleavage of the extracellular domains of these receptors. Soluble TNF-Rs act as TNF antagonists and can inhibit TNFalpha-mediated proinflammatory effects.

METHODS

Levels of sTNF-RI + II were measured using commercially available enzyme-linked immunosorbent assays (ELISAs). Serum levels of sTNF-RI + II of 76 healthy volunteers were compared to serum levels of 373 clinically well-characterized patients with Crohn's disease (CD) and 118 patients with ulcerative colitis (UC) with different disease activity from the German IBD competence network serum bank. CD patient subgroups were defined according to the Vienna Classification.

RESULTS

The serum levels of sTNF-RI were significantly increased in all groups (active, chronic active, and remission) of CD and UC patients compared to healthy controls. sTNF-RII levels were significantly higher in active CD patients compared to UC patients with no overlap of the 95% confidence interval. Significantly higher values of sTNF-RII compared to controls were also observed in CD patients and UC patients in remission. There was no statistically significant difference in sTNF-RI or sTNF-RII levels when patient subgroups were analyzed according to disease behavior or disease localization.

CONCLUSION

sTNF-RI is upregulated in the serum of IBD patients compared to healthy controls and could be used as a marker for disease activity. sTNF-RII levels are significantly more elevated in serum of active CD patients as compared to UC and could be used as an additional parameter to discriminate both diseases.

Acquired T-cell sensitivity to TRAIL mediated killing during HIV infection is regulated by CXCR4-gp120 interactions

BACKGROUND

Sensitivity towards apoptosis induced by ligation of the tumor necrosis factor family of death receptors is controlled in part by death receptor expression. Whereas cellular activation enhances Fas receptor expression and induces Fas sensitivity, such cellular activation neither alters TRAIL receptor expression nor induces TRAIL sensitivity. Cells infected by HIV acquire sensitivity to TRAIL induced death, although the mechanisms by which this is achieved are undefined.

OBJECTIVE

To define the mechanism by which cells from HIV infected patients acquire sensitivity to TRAIL mediated killing.

DESIGN

In vitro assessment of TRAIL receptor expression and TRAIL sensitivity.

METHODS

Treatment of Jurkat T cells, peripheral blood lymphocytes from HIV negative donors, or human osteogenic seroma (HOS) cells expressing CD4, CXCR4 or CCR5 with T tropic gp120, M tropic gp120, or agonistic antibodies against CD4, CXCR4 or CCR5. TRAIL receptors were measured by flow cytometry or reverse transcription-PCR and TRAIL sensitivity was assessed by incubation with recombinant TRAIL followed by Annexin V fluorescein isothiocyanate/Propidium Iodide (PI) staining.

RESULTS

Treatment of uninfected Jurkat T cells, as well as primary T cells with gp120 results in the upregulation of TRAIL death receptor expression and acquired sensitivity to TRAIL mediated cell death. The increase in TRAIL death receptor expression and acquisition of TRAIL sensitivity requires the chemokine coreceptor CXCR4 but not CCR5 or the CD4 receptor.

CONCLUSIONS

These results indicate that chemokine receptor interactions regulate TRAIL receptor expression and provide an explanation for the acquired T cell sensitivity to TRAIL mediated killing death during HIV infection.