Tobacco smoking effect on HIV-1 pathogenesis: role of cytochrome P450 isozymes

Brief Report: HIV Infection Does Not Explain Higher Nicotine Metabolism in People Living With HIV

BACKGROUND

Smoking contributes to significant morbidity and mortality in people with HIV. People with HIV have relatively high nicotine metabolism rates, as measured by the nicotine metabolite ratio (NMR, 3-hydroxycotinine/cotinine). A higher NMR is associated with difficulty quitting smoking. We hypothesized that HIV infection might upregulate nicotine metabolism.

SETTING

A retrospective study of male current smokers in the Multicenter AIDS Cohort Study who HIV seroconverted between 1985 and 1993.

METHODS

Eligibility included having plasma stored before and after confirmed HIV seroconversion and current tobacco use. Samples were selected from the closest available visits before (median 3.3 months) and after (median 9.4 months) seroconversion. Antiretroviral therapy use was exclusionary. Cotinine and 3-hydroxycotinine were measured using liquid chromatography-tandem mass spectrometry. We compared NMR from plasma pre-HIV and post-HIV infection using signed-rank tests. We targeted a sample size of 71 pairs to achieve 80% power to detect a 0.1 unit increase in NMR with P = 0.05.

RESULTS

We analyzed paired samples from 78 participants; the median age was 34.5 years [interquartile range (IQR 29-40 years)]. The median NMR pre-HIV and post-HIV was 0.45 (IQR 0.32-0.54) and 0.46 (IQR 0.34-0.56), respectively. The median change in NMR postseroconversion was +0.01 (IQR -0.05, +0.09), P = 0.25. Stratification of median change in NMR by timing between samples or time since HIV seroconversion did not alter this finding.

CONCLUSIONS

Acquiring HIV had no measurable effect on NMR. We postulate that upregulation of the NMR may be due to direct pharmacologic effects of HIV medications or metabolic changes in response to HIV infection.

Association of Substance Use with Immunological Response to Antiretroviral Therapy in HIV-Positive Patients from Southwest Ethiopia: A Prospective Observational Study

Background

Use of psychoactive substances by HIV-positive patients in the course of antiretroviral drug treatment has become a public health problem globally. Substance use (alcohol, nicotine, and khat) during the course of treatment results in interactions with drugs that lead to undesired treatment outcomes. This condition is understudied, and the consequences of substance use among patients on antiretroviral treatment are not well explored.

Methods

A prospective observational study was conducted among people on antiretroviral therapy (ART) at Jimma University Medical Center in southwest Ethiopia from April 20 to November 27, 2019. Data were collected using the World Health Organization's alcohol, smoking, and substance involvement screening test among adults who have followed antiretroviral therapy for a minimum of 6 months. Logistic regression analysis was done to identify factors associated with immunological response. The inadequate immunological response was defined as patients who were unable to achieve or maintain a CD4 cell count of >350 cells/mm³ after the 6-months of follow-up.

Results

Of the 332 patients enrolled, a majority (64.2%) of the respondents were females. The mean (±SD) age of the patients was 38.5 ± 9.5 years. The proportion of participants with a high level of health risk due to alcohol use was 8.4%, while 63.8% of them were non-alcohol users with no health risk. In multivariable logistic regression analysis, moderate and high levels of health risks from alcohol use were significantly associated with increased odds of inadequate immunological response (AOR: 2.9; 95% CI, 1.1-7.4) and (AOR: 4.3; 95% CI, 1.2-14.8), respectively, but the level of health risk from khat and cigarette use showed no association with inadequate immunological response in this study.

Conclusion

Moderate and high levels of health risk from alcohol use were independently associated with inadequate immunological response. People living with HIV/AIDS should regularly be screened for and be educated about substance use and its potential negative impact on CD4 cell recovery.

Effect of benzo(a)pyrene on oxidative stress and inflammatory mediators in astrocytes and HIV-infected macrophages

BACKGROUND

Benzo(a)pyrene (BaP), an important polycyclic aromatic hydrocarbons (PAH) component of cigarette/tobacco smoking, is known to cause adverse health effects and is responsible for various life-threatening conditions including cancer. However, it is not yet clear whether BaP contributes to the macrophage- and astrocyte-mediated inflammatory response.

METHODS

We examined the acute (up to 72 h) effects of BaP on the expression of antioxidant enzymes (AOEs), cytokines/chemokines, and cytochromes P450 (CYP) enzymes in astrocytic cell lines, SVGA, and chronically HIV-infected U1 macrophage. The treated cells were examined for mRNA, protein levels of CYPs, AOEs superoxide dismutase-1 (SOD1) and catalase (CAT), cytokines/chemokines, using Western blot, multiplex ELISA, and reactive oxygen species (ROS) by flow cytometry analysis.

RESULTS

Upon acute exposure, BaP (1 μM) showed a significant increase in the mRNA levels of CYPs (CYP1A1 and CYP1B1), and pro-inflammatory cytokine IL-1β in SVGA cells following BaP for 24, 48, and 72h. In addition, we observed a significant increase in the mRNA levels of SOD1 and CAT at 24h of BaP treatment. In contrast, BaP did not exert any change in the protein expression of AOEs and CYP enzymes. In U1 cells, however, we noticed an interesting increase in the levels of MCP-1 as well as a modest increase in TNFα, IL-8 and IL-1β levels observed at 72 h of BaP treatment but could not reach to statistically significant level.

CONCLUSIONS

Overall, these results suggest that BaP contributes in part to macrophage and astrocyte-mediated neuroinflammation by mainly inducing IL-1β and MCP-1 production, which is likely to occur with the involvement of CYP and/or oxidative stress pathways.

Plasma extracellular vesicles in people living with HIV and type 2 diabetes are related to microbial translocation and cardiovascular risk

HIV and type 2 diabetes (T2D) are both associated with gut microbiota alterations, low-grade endotoxemia and increased cardiovascular risk. We investigated the potential role of plasma extracellular vesicles (EVs) in relation to these processes. Plasma EVs were isolated by size exclusion chromatography in fasting individuals with HIV and T2D (n = 16), T2D only (n = 14), HIV only (n = 20) or healthy controls (n = 19), and characterized by transmission electron microscopy, western blot, nanoparticle tracking analysis and quantitative proteomics. The findings were compared to gut microbiota alterations, lipopolysaccharide levels and cardiovascular risk profile. Individuals with concomitant HIV and T2D had higher plasma EV concentration, which correlated closely with plasma lipopolysaccharides, triglycerides and Framingham score, but not with gut microbiota alterations. Proteomic analyses identified 558 human proteins, largely related to cardiometabolic disease genes and upstream regulation of inflammatory pathways, including IL-6 and IL-1β, as well as 30 bacterial proteins, mostly from lipopolysaccharide-producing Proteobacteria. Our study supports that EVs are related to microbial translocation processes in individuals with HIV and T2D. Their proteomic content suggests a contributing role in low-grade inflammation and cardiovascular risk development. The present approach for exploring gut-host crosstalk can potentially identify novel diagnostic biomarkers and therapeutic targets.

Nicotine self-administration with menthol and audiovisual cue facilitates differential packaging of CYP2A6 and cytokines/chemokines in rat plasma extracellular vesicles

In this study, we investigated whether intravenously self-administered nicotine with menthol and audiovisual cue modulates nicotine-metabolizing CYP2A6, oxidative stress modulators, and cytokines/chemokines in plasma extracellular vesicles (EVs) in rats. We assigned rats to self-administered nicotine with: (a) audiovisual cue (AV), (b) menthol, and (c) menthol and AV cue. We found increased levels of CD9 in plasma EVs after self-administered nicotine with menthol and AV cue. Moreover, expression of CYP2A6 in plasma EVs was significantly increased after self-administered nicotine in response to menthol and AV cue. However, despite an upward trend on SOD1 and catalase, increase was not found to be statistically significant, while total antioxidant capacity was found to be significantly increased in plasma and plasma EVs obtained after self-administered nicotine with menthol and AV cue. Among cytokine and chemokine profiling, we found a significant increase in the levels of MCP-1 after self-administered nicotine with menthol and AV cue and complete packaging of IL-1β in EVs. Taken together, the study provides evidence that nicotine in response to menthol and AV cues can package altered levels of CYP2A6, and cytokines/chemokines in plasma EVs that may contribute to cell–cell communication, nicotine metabolism, and inflammation upon cigarette smoking.

Independent and Combined Effects of Nicotine or Chronic Tobacco Smoking and HIV on the Brain: A Review of Preclinical and Clinical Studies

Tobacco smoking is highly prevalent among HIV-infected individuals. Chronic smokers with HIV showed greater cognitive deficits and impulsivity, and had more psychopathological symptoms and greater neuroinflammation than HIV non-smokers or smokers without HIV infection. However, preclinical studies that evaluated the combined effects of HIV-infection and tobacco smoking are scare. The preclinical models typically used cell cultures or animal models that involved specific HIV viral proteins or the administration of nicotine to rodents. These preclinical models consistently demonstrated that nicotine had neuroprotective and anti-inflammatory effects, leading to cognitive enhancement. Although the major addictive ingredient in tobacco smoking is nicotine, chronic smoking does not lead to improved cognitive function in humans. Therefore, preclinical studies designed to unravel the interactive effects of chronic tobacco smoking and HIV infection are needed. In this review, we summarized the preclinical studies that demonstrated the neuroprotective effects of nicotine, the neurotoxic effects of the HIV viral proteins, and the scant literature on nicotine or tobacco smoke in HIV transgenic rat models. We also reviewed the clinical studies that evaluated the neurotoxic effects of tobacco smoking, HIV infection and their combined effects on the brain, including studies that evaluated the cognitive and behavioral assessments, as well as neuroimaging measures. Lastly, we compared the different approaches between preclinical and clinical studies, identified some gaps and proposed some future directions. Graphical abstract Independent and combined effects of HIV and tobacco/nicotine. Left top and bottom panels: Both clinical studies of HIV infected persons and preclinical studies using viral proteins in vitro or in vivo in animal models showed that HIV infection could lead to neurotoxicity and neuroinflammation. Right top and bottom panels: While clinical studies of tobacco smoking consistently showed deleterious effects of smoking, clinical and preclinical studies that used nicotine show mild cognitive enhancement, neuroprotective and possibly anti-inflammatory effects. In the developing brain, however, nicotine is neurotoxic. Middle overlapping panels: Clinical studies of persons with HIV who were smokers typically showed additive deleterious effects of HIV and tobacco smoking. However, in the preclinical studies, when nicotine was administered to the HIV-1 Tg rats, the neurotoxic effects of HIV were attenuated, but tobacco smoke worsened the inflammatory cascade.

Cellular stress responses and dysfunctional Mitochondrial-cellular senescence, and therapeutics in chronic respiratory diseases

The abnormal inflammatory responses due to the lung tissue damage and ineffective repair/resolution in response to the inhaled toxicants result in the pathological changes associated with chronic respiratory diseases. Investigation of such pathophysiological mechanisms provides the opportunity to develop the molecular phenotype-specific diagnostic assays and could help in designing the personalized medicine-based therapeutic approaches against these prevalent diseases. As the central hubs of cell metabolism and energetics, mitochondria integrate cellular responses and interorganellar signaling pathways to maintain cellular and extracellular redox status and the cellular senescence that dictate the lung tissue responses. Specifically, as observed in chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis, the mitochondria-endoplasmic reticulum (ER) crosstalk is disrupted by the inhaled toxicants such as the combustible and emerging electronic nicotine-delivery system (ENDS) tobacco products. Thus, the recent research efforts have focused on understanding how the mitochondria-ER dysfunctions and oxidative stress responses can be targeted to improve inflammatory and cellular dysfunctions associated with these pathologic illnesses that are exacerbated by viral infections. The present review assesses the importance of these redox signaling and cellular senescence pathways that describe the role of mitochondria and ER on the development and function of lung epithelial responses, highlighting the cause and effect associations that reflect the disease pathogenesis and possible intervention strategies.

Circulatory Astrocyte and Neuronal EVs as Potential Biomarkers of Neurological Dysfunction in HIV-Infected Subjects and Alcohol/Tobacco Users

The diagnosis of neurocognitive disorders associated with HIV infection, alcohol, and tobacco using CSF or neuroimaging are invasive or expensive methods, respectively. Therefore, extracellular vesicles (EVs) can serve as reliable noninvasive markers due to their bidirectional transport of cargo from the brain to the systemic circulation. Hence, our objective was to investigate the expression of astrocytic (GFAP) and neuronal (L1CAM) specific proteins in EVs circulated in the plasma of HIV subjects, with and without a history of alcohol consumption and tobacco smoking. The protein expression of GFAP (p < 0.01) was significantly enhanced in plasma EVs obtained from HIV-positive subjects and alcohol users compared to healthy subjects, suggesting enhanced activation of astrocytes in those subjects. The L1CAM expression was found to be significantly elevated in cigarette smokers (p < 0.05). However, its expression was not found to be significant in HIV subjects and alcohol users. Both GFAP and L1CAM levels were not further elevated in HIV-positive alcohol or tobacco users compared to HIV-positive nonsubstance users. Taken together, our data demonstrate that the astrocytic and neuronal-specific markers (GFAP and L1CAM) can be packaged in EVs and circulate in plasma, which is further elevated in the presence of HIV infection, alcohol, and/or tobacco. Thus, the astroglial marker GFAP and neuronal marker L1CAM may represent potential biomarkers targeting neurological dysfunction upon HIV infection and/or alcohol/tobacco consumption.

Attributes of HIV infection over decades (1982-2018): A systematic review and meta-analysis

Understanding the risk factors for HIV infection is the foundation of successful preventive strategies, which must bundle sociocultural, behavioural and biomedical interventions to halt disease transmission. We aimed in this study to provide a pooled estimation of HIV risk factors and trace changes across decades in order to drive consensus and accurate assessment of disease transmission risk. We comprehensively searched PubMed, ISI Web of Knowledge, Medline, EMBASE, ScienceDirect, Ovid, EBSCO, Google Scholar and the Egyptian Universities Library Consortium from October to December 2018. Two independent reviewers extracted data from eligible studies. Funnel plots were inspected to identify publication bias. Heterogeneity across studies was checked using the Q and I² statistics. The results were reported based on the pooled odds ratio (pOR) with 95% CI using a random-effects model. Meta-analysis of HIV risk factors revealed a superior role for risky sexual practices (unprotected vaginal/anal sex), injecting drug use (IDU), sharing needles, sexually transmitted infections (STIs), child sexual abuse and vertical transmissions. Trends across decades (1982-1999 and 2000-2018, respectively) showed rising evidence for prostitution [pOR (95% CI)= 2.3 (1.12-4.68) versus 2.69 (1.67-4.32)] and men who have sex with men (MSM) [pOR (95% CI)= 2.28 (1.64-3.17) versus 3.67 (1.88-7.17)], while transmission through IDU [pOR (95% CI)= 3.42 (2.28-5.12) versus 2.16 (1.74-2.70)], alcoholism [pOR (95% CI)= 2.35 (0.73-7.59) versus 1.71(1.08-2.72)], and sharing syringes [pOR (95% CI)= 6.10 (2.57-14.5) versus 2.70 (2.01-6.35)] showed notable decline. Harm reduction programs and condom use have been recognized as chief HIV prevention strategies, while male circumcision contributed a partial role. Collectively, sexual risk factors continue to be a key driver of the global HIV epidemic. Persistent and emerging risk factors identified in our analysis should constitute the forefront targets of HIV prevention programmes to accelerate efforts towards HIV elimination.

Extracellular Vesicles in Smoking-Mediated HIV Pathogenesis and their Potential Role in Biomarker Discovery and Therapeutic Interventions

In the last two decades, the mortality rate in people living with HIV/AIDS (PLWHA) has decreased significantly, resulting in an almost normal longevity in this population. However, a large portion of this population still endures a poor quality of life, mostly due to an increased inclination for substance abuse, including tobacco smoking. The prevalence of smoking in PLWHA is consistently higher than in HIV negative persons. A predisposition to cigarette smoking in the setting of HIV potentially leads to exacerbated HIV replication and a higher risk for developing neurocognitive and other CNS disorders. Oxidative stress and inflammation have been identified as mechanistic pathways in smoking-mediated HIV pathogenesis and HIV-associated neuropathogenesis. Extracellular vesicles (EVs), packaged with oxidative stress and inflammatory agents, show promise in understanding the underlying mechanisms of smoking-induced HIV pathogenesis via cell-cell interactions. This review focuses on recent advances in the field of EVs with an emphasis on smoking-mediated HIV pathogenesis and HIV-associated neuropathogenesis. This review also provides an overview of the potential applications of EVs in developing novel therapeutic carriers for the treatment of HIV-infected individuals who smoke, and in the discovery of novel biomarkers that are associated with HIV-smoking interactions in the CNS.

Bidirectional Associations among Nicotine and Tobacco Smoke, NeuroHIV, and Antiretroviral Therapy

People living with HIV (PLWH) in the antiretroviral therapy (ART) era may lose more life-years to tobacco use than to HIV. Yet, smoking rates are more than twice as high among PLWH than the general population, contributing not just to mortality but to other adverse health outcomes, including neurocognitive deficits (neuroHIV). There is growing evidence that synergy with chronic inflammation and immune dysregulation that persists despite ART may be one mechanism by which tobacco smoking contributes to neuroHIV. This review will summarize the differential effects of nicotine vs tobacco smoking on inflammation in addition to the effects of tobacco smoke components on HIV disease progression. We will also discuss biomarkers of inflammation via neuroimaging as well as biomarkers of nicotine dependence (e.g., nicotine metabolite ratio). Tobacco smoking and nicotine may impact ART drug metabolism and conversely, certain ARTs may impact nicotine metabolism. Thus, we will review these bidirectional relationships and how they may contribute to neuroHIV and other adverse outcomes. We will also discuss the effects of tobacco use on the interaction between peripheral organs (lungs, heart, kidney) and subsequent CNS function in the context of HIV. Lastly, given the dramatic rise in the use of electronic nicotine delivery systems, we will discuss the implications of vaping on these processes. Despite the growing recognition of the importance of addressing tobacco use among PLWH, more research is necessary at both the preclinical and clinical level to disentangle the potentially synergistic effects of tobacco use, nicotine, HIV, cognition and immune dysregulation, as well as identify optimal approaches to reduce tobacco use. Graphical Abstract Proposed model of the relationships among HIV, ART, smoking, inflammation, and neurocognition. Solid lines represent relationships supported by evidence. Dashed lines represent relationships for which there is not enough evidence to make a conclusion. (a) HIV infection produces elevated levels of inflammation even among virally suppressed individuals. (b) HIV is associated with deficits in cognition function. (c) Smoking rates are higher among PLWH, compared to the general population. (d) The nicotine metabolite ratio (NMR) is associated with smoking behavior. (e) HIV and tobacco use are both associated with higher rates of psychiatric comorbidities, such as depression, and elevated levels of chronic stress. These factors may represent other mechanisms linking HIV and tobacco use. (f) The relationship between nicotine, tobacco smoking, and inflammation is complex, but it is well-established that smoking induces inflammation; the evidence for nicotine as anti-inflammatory is supported in some studies, but not others. (g) The relationship between tobacco use and neurocognition may differ for the effects of nicotine (acute nicotine use may have beneficial effects) vs. tobacco smoking (chronic use may impair cognition). (h) Elevated levels of inflammation may be associated with deficits in cognition. (i) PLWH may metabolize nicotine faster than those without HIV; the mechanism is not yet known and the finding needs validation in larger samples. We also hypothesize that if HIV-infection increases nicotine metabolism, then we should observe an attenuation effect once ART is initiated. (j) It is possible that the increase in NMR is due to ART effects on CYP2A6. (k) We hypothesize that faster nicotine metabolism may result in higher levels of inflammation since nicotine has anti-inflammatory properties.

Circulating Extracellular Vesicles Containing Xenobiotic Metabolizing CYP Enzymes and Their Potential Roles in Extrahepatic Cells Via Cell-Cell Interactions

The cytochrome P450 (CYP) family of enzymes is known to metabolize the majority of xenobiotics. Hepatocytes, powerhouses of CYP enzymes, are where most drugs are metabolized into non-toxic metabolites. Additional tissues/cells such as gut, kidneys, lungs, blood, and brain cells express selective CYP enzymes. Extrahepatic CYP enzymes, especially in kidneys, also metabolize drugs into excretable forms. However, extrahepatic cells express a much lower level of CYPs than hepatocytes. It is possible that the liver secretes CYP enzymes, which circulate via plasma and are eventually delivered to extrahepatic cells (e.g., brain cells). CYP circulation likely occurs via extracellular vesicles (EVs), which carry important biomolecules for delivery to distant cells. Recent studies have revealed an abundance of several CYPs in plasma EVs and other cell-derived EVs, and have demonstrated the role of CYP-containing EVs in xenobiotic-induced toxicity via cell–cell interactions. Thus, it is important to study the mechanism for packaging CYP into EVs, their circulation via plasma, and their role in extrahepatic cells. Future studies could help to find novel EV biomarkers and help to utilize EVs in novel interventions via CYP-containing EV drug delivery. This review mainly covers the abundance of CYPs in plasma EVs and EVs derived from CYP-expressing cells, as well as the potential role of EV CYPs in cell–cell communication and their application with respect to novel biomarkers and therapeutic interventions.

Tobacco and Antiretrovirals Modulate Transporter, Metabolic Enzyme, and Antioxidant Enzyme Expression and Function in Polarized Macrophages

BACKGROUND

Cigarette smoking increases systemic oxidative stress, inflammation, and viral replication in individuals with HIV. Macrophages are infected during HIV infection and serve as an important reservoir throughout the process. Macrophages exist in two phenotypes, the classically activated M1 macrophage and alternatively activated M2 macrophage. The expression of drug efflux transporters and metabolic enzymes, which have direct effects on intracellular drug concentrations, differ between the pro-inflammatory M1 macrophage and the anti-inflammatory M2 macrophage.

OBJECTIVE

To further explain the role of tobacco use in worsened outcomes in the HIV + population receiving antiretroviral therapy.

METHODS

Western blotting was used to examine macrophage polarization and expression of drug efflux transporters, CYP enzymes, and antioxidant enzymes. The arginase assay was used to measure arginase activity. Cytokine production was measured using the human multiplex inflammatory cytokine assay kit. The 8-OHdG DNA Damage Quantification Direct Kit was used to quantify DNA damage. Viral replication under the influence of tobacco and antiretroviral drug use was measured by p24 Elisa.

RESULTS

We observed phenotypic shifts from M1 to M2 with both individual and combination treatments with cigarette smoke condensate and the protease inhibitor antiretroviral drug lopinavir. These shifts lead to changes in cytokine production, the expression of CYP enzymes, anti-oxidant enzymes, and drug efflux transporters, as well as changes in viral replication.

CONCLUSION

This data suggest a mechanism by which tobacco use impairs HIV antiretroviral therapy to increase intracellular drug concentrations in this important cellular reservoir.

Differences in the rate of nicotine metabolism among smokers with and without HIV

OBJECTIVE

HIV-infected smokers lose more life years to tobacco use than to HIV infection. The nicotine metabolite ratio (NMR), a biomarker of CYP2A6, represents individual variation in the rate at which nicotine is metabolized and is associated with response to smoking cessation treatments. We evaluated whether HIV-infected smokers metabolize nicotine faster than HIV-uninfected smokers, which may contribute to the disproportionate smoking burden and may have important treatment implications.

DESIGN

We analysed baseline data from two clinical trials (NCT01710137; NCT01314001) to compare the NMR in HIV-infected smokers (N = 131) to HIV-uninfected smokers (N = 199).

METHODS

Propensity scores were used to match the groups 2 : 1 on characteristics that influence NMR: sex, race, BMI and smoking rate. Nicotine metabolites were assessed via liquid chromatography-tandem mass spectrometry methods and the ratio of 3-hydroxycotinine:cotinine was used to compute the NMR.

RESULTS

HIV-infected smokers had significantly higher NMR (mean = 0.47, SEM = 0.02) and were more likely to be in the highest NMR quartile compared with HIV-uninfected smokers (mean = 0.34, SEM = 0.02; Ps < 0.001).

CONCLUSION

The higher NMR observed among HIV-infected smokers may partially explain higher smoking rates and lower response to transdermal nicotine therapy. Understanding the mechanisms by which HIV and/or ART contribute to faster nicotine metabolism may guide the use of the NMR to personalize tobacco cessation strategies in this underserved population.

Impact of Tobacco Smoke in HIV Progression: a Major Risk Factor for the Development of NeuroAIDS and Associated of CNS Disorders

Aim

With the advent of highly active and combination antiretroviral therapy have substantially increased the life expectancy of patients infected with human immunodeficiency virus (HIV). However, this has brought into sharp contrast the incidence of several 'Non-acquired immunodeficiency syndrome (AIDS) diseases such as NeuroAIDS which identifies a group of neurological disorders caused primarily by HIV-mediated damage to the central and peripheral nervous systems. Given the patients depleted immune condition, the use and abuse of drug and addictive substances such as tobacco smoking can further deteriorates their overall health and accelerate the progression and severity of the disease. In this review we detail the pathogenesis, progression and characteristics of HIV and the impact of tobacco smoking as a risk factor for the progression of the disease to NeuroAIDS. This is a poorly understood aspect of HIV-related complications that needs to be addressed.

Subjects and methods

Review of theoretical approaches and knowledge synthesis.

Results

Tobacco smoking is highly prevalent in HIV patients when compared to the general population. The oxidative damage and inflammatory stress caused by chronic smoking on the cerebrovascular system have been well established. Considering that HIV patients have an impaired immune system and smokers per se are more susceptible to viral and bacterial inflammatory neuropathologies than non-smokers, it is conceivable that tobacco smoking as a risk factor for the progression of HIV into NeuroAIDS and related neurological impairments.

Conclusion

Tobacco smoke (TS) may bring about a synergistic effect in the context of persistent inflammatory state and cerebrovascular damage which facilitate HIV infection and progression to NeuroAIDS when compared to non-smokers.

A retrospective analysis of dental implant survival in HIV patients

AIM

This 5 years retrospective cohort survival study compared failure rates of dental implants placed in HIV (+) and HIV (-) patients relative to several risk factors.

MATERIALS AND METHODS

Between 2006 and 2015, 484 implants placed in HIV (+) patients and 805 implants placed in HIV (-) patients were assessed for survival. The effects of HIV were estimated using propensity weighting. The effects of age, smoking status, diabetes, restoration status, gender, implant type, placement site, hepatitis C status, baseline CD4 count and CD4%, post-placement average CD4%, nadir CD4%, nadir CD4 count and antiviral therapy were analysed.

RESULTS

Implants placed in HIV (+) patients and HIV (-) patients had similar failure rates (HR = 1.4, p = 0.34). Increased failure rates were observed in HIV (+) patients with baseline CD4% ≤20 (HR = 2.72, p = 0.04), post-placement CD4% average ≤20% (HR = 2.71, p = 0.04), protease inhibitor administration (HR = 2.74, p = 0.04), smoking (HR = 2.61, p = 0.05) and anterior maxillary placement (HR = 5.82, p < 0.01). Hepatitis C coinfection, viral titre, baseline CD4 count, gender, implant type and restoration type were non-contributory.

CONCLUSION

Implants placed in HIV (+) patients had similar survival rates as HIV (-) patients. Failure rates increase significantly when confounding risk factors are present in HIV (+) patients.

Brief Report: Rate of Nicotine Metabolism and Tobacco Use Among Persons With HIV: Implications for Treatment and Research

BACKGROUND

The nicotine metabolite ratio (NMR) is a biomarker that represents individual variation in the speed that nicotine is metabolized. The rate of nicotine metabolism alters smoking behavior (eg, amount) and has been validated for personalizing tobacco dependence medication selection to increase treatment efficacy and reduce treatment side effects in the general population of smokers. Although smoking rates are extremely high among those with HIV, the NMR has not been evaluated in this underserved population.

METHODS

We used baseline data from a smoking cessation clinical trial for smokers with HIV (N = 131) to examine associations between NMR and demographic, smoking, disease-related, and psychological characteristics. Pearson r and analysis of variance were used to identify univariate correlates of NMR, which were then entered into a multiple linear regression model.

RESULTS

In univariate analyses, a higher NMR (faster nicotine metabolism) was associated with being white, and more cigarettes per day, nicotine dependence, exhaled carbon monoxide, and symptoms of depression and anxiety, and using efavirenz. In a multiple regression model, a higher NMR was associated with more cigarettes per day, higher anxiety symptoms, and efavirenz use.

CONCLUSIONS

As in other populations, faster nicotine metabolism was associated with the use of more cigarettes and higher anxiety symptoms. Notably, efavirenz use was associated with faster metabolism, which might make it harder to quit smoking for people with HIV treated with that medication. These findings could help guide further study and the clinical use of the NMR to personalize nicotine dependence treatment in this underserved population.

Effects of Tobacco Usage and Antiretroviral Therapy on Biomarkers of Systemic Immune Activation in HIV-Infected Participants

Like HIV infection, smoking, which is common among HIV-infected persons, is associated with chronic, systemic inflammation. However, the possible augmentative effects of HIV infection and smoking and other types of tobacco usage on indices of systemic inflammation and the impact of combination antiretroviral therapy (cART) thereon remain largely unexplored and represent the focus of the current study. Of the total number of HIV-infected persons recruited to the study (n = 199), 100 were categorised as pre-cART and 99 as virally suppressed (HIV viral load < 40 copies/mL). According to serum cotinine levels, 144 and 55 participants were categorised as nonusers and users of tobacco, respectively. In addition to cytokines (IL-6, IL-8, and TNF-α) and chemokines (IP-10, MIG, IL-8, MCP-1, and RANTES), other biomarkers of systemic inflammation included C-reactive protein (CRP), β2-microglobulin, and those of neutrophil activation [ICAM-1, L-selectin, matrix metalloproteinase-9 (MMP-9)], microbial translocation (soluble CD14, LPS-binding protein), and oxidative stress (cyclophilin A, surfactant D). These were measured using multiplex bead array, ELISA, and immunonephelometric procedures. Viral suppression was associated with significant decreases in the levels of most of the biomarkers tested (P < 0.0037-0.0008), with the exceptions of CRP, cyclophilin A, and MMP-9. With respect to tobacco usage, irrespective of cART status, circulating levels of β2-microglobulin, cyclophilin A, and RANTES were significantly elevated (P < 0.042-0.012) in users vs nonusers. Additional analysis of the groups of tobacco users and nonusers according to cART status revealed high levels of RANTES in pre-cART/tobacco users relative to the three other subgroups (P < 0.004-0.0001), while more modest increases in cyclophilin A and MMP-9 (P < 0.019-0.027) were observed in comparison with the cART/tobacco user subgroup. Notwithstanding the efficacy of cART in attenuating HIV-associated, chronic systemic inflammation, the current study has identified RANTES as being significantly and seemingly selectively increased in those with active HIV infection who use tobacco, a mechanism which may underpin augmentative proinflammatory activity.

Modulatory Effects of Nicotine on neuroHIV/neuroAIDS

Nicotine, one of the key active ingredients in tobacco smoke, exerts its effects via binding to nicotinic acetylcholine receptors (nAChRs). Although both negative and positive pharmacological effects of nicotine have been shown in numerous animals and human studies, its interaction with human immunodeficiency virus-1 (HIV-1) have not been fully elucidated. Even though combined anti-retroviral therapy (cART) limits the progression of HIV-1 to acquired immune deficiency syndrome (AIDS), HIV-associated neurocognitive disorders (HAND) remain prevalent. There is thus a compelling need to enhance our understanding of HAND-related neurologic dysfunction. Some biochemical pathways and physiological dysfunctions have been found to be shared by HAND and Alzheimer's (AD) or Parkinson's (PD) diseases, and nicotine may exert the same neuroprotection in HAND that has been observed in both AD and PD. In the past dozen years, various potential therapeutic effects of nicotine such as neuroprotection have been revealed in both in vivo and in vitro studies, including using HIV-1 transgenic (HIV-1Tg) rat model, which mimics HIV-infected patients receiving cART. In the current review, we describe recent progress in the prevalence of HIV/AIDS with and without cigarette smoking, some animal models for studying neural dysfunction associated with HIV-1 infection, elucidating the modulatory effects of cigarette smoking/nicotine on HIV/AIDS, the anti-inflammatory effects of nicotine, and the neuroprotective effects observed in HIV-1Tg rat model. Taken together, these findings suggest the following: although tobacco smoking does cause deleterious effects in both health and disease conditions such as HIV infection, nicotine, the significant component of tobacco smoke, has been shown to possess some neuroprotective effects in HIV patients, possible via its anti-inflammatory activities. It is therefore necessary to study nicotine's dual effects on neuroHIV/neuroAIDS in hope of better defining the potential medical uses of nicotine or its analogues, and to make them available in a purer and less dangerous form.

Benzo(a)pyrene in Cigarette Smoke Enhances HIV-1 Replication through NF-κB Activation via CYP-Mediated Oxidative Stress Pathway

Smoking aggravates HIV-1 pathogenesis and leads to decreased responses to antiretroviral therapy. In this study, we aim to find a molecular mechanism that would explain smoking-induced HIV-1 replication. Benzo(a)pyrene (BaP), a major carcinogen in cigarette, requires metabolic activation through cytochrome P450s (CYPs) to exert its toxic effects. We hypothesized that CYP-mediated BaP metabolism generates reactive oxygen species (ROS), and the resultant oxidative stress aggravates HIV-1 replication. As expected, we observed ~3 to 4-fold increase in HIV-1 replication in U1 cells and human primary macrophages after chronic BaP exposure. We also observed ~30-fold increase in the expression of CYP1A1 at mRNA level, ~2.5-fold increase in its enzymatic activity as well as elevated ROS and cytotoxicity in U1 cells. The knock-down of the CYP1A1 gene using siRNA and treatment with selective CYP inhibitors and antioxidants significantly reduced HIV-1 replication. Further, we observed a nuclear translocation of NF-κB subunits (p50 and p65) after chronic BaP exposure, which was reduced by treatment with siRNA and antioxidants/CYP inhibitors. Suppression of NF-κB pathway using specific NF-κB inhibitors also significantly reduced HIV-1 replication. Altogether, our results suggest that BaP enhances HIV-1 replication in macrophages by a CYP-mediated oxidative stress pathway followed by the NF-κB pathway.

Baseline Cigarette Smoking Status as a Predictor of Virologic Suppression and CD4 Cell Count During One-Year Follow-Up in Substance Users with Uncontrolled HIV Infection

Cigarette smoking is prevalent in people living with HIV/AIDS (PLHIV) who abuse alcohol and/or illicit substances. This study evaluated whether smoking is predictive of virologic non-suppression (> 200 copies/mL) and low CD4 count (< 200 cells/mm³) during 1-year follow-up in medically hospitalized, substance-using PLHIV recruited for a multi-site trial. Smoking status was assessed with the Heaviness of Smoking Index (HSI). Analyses revealed that, controlling for baseline differences and adherence to antiretroviral therapy, non-smokers (n = 237), compared to smokers scoring in the medium-to-high range on the HSI (n = 386), were significantly more likely to achieve viral suppression (OR 1.50, 95% CI 1.02, 2.20). There was a significant smoking-by-time interaction for CD4 cell count (χ²(1) = 4.08, p < .05), with smokers less likely to have low CD4 count at baseline and 6-month follow-up, but more likely to have low CD4 count at 12-month follow-up. The results suggest that smoking may play a role in immunological functioning in HIV-infected substance users. ClinicalTrials.gov Identifier: NCT01612169.

Cigarette smoke promotes HIV infection of primary bronchial epithelium and additively suppresses CFTR function

Recurrent lung infections are a common cause of morbidity and mortality in people living with HIV and this is exacerbated in smokers even when administered combination antiretroviral therapy (cART). The incidence of pneumonia is increased with smoking and treatment interruption and is directly dependent on viral load in patients when adjusted for CD4 counts. CFTR dysfunction plays an important role in aberrant airway innate immunity as it is pivotal in regulating mucociliary clearance (MCC) rates and other antibacterial mechanisms of the airway. In our earlier work, we have demonstrated that bronchial epithelium expresses canonical HIV receptors CD4, CCR5 and CXCR4 and can be infected with HIV. HIV Tat suppresses CFTR mRNA and function via TGF-β signaling. In the present study, we demonstrate that cigarette smoke (CS) potentiates HIV infection of bronchial epithelial cells by upregulating CD4 and CCR5 expression. HIV and CS individually and additively suppress CFTR biogenesis and function, possibly explaining the increased incidence of lung infections in HIV patients and its exacerbation in HIV smokers.

Monocyte-derived exosomes upon exposure to cigarette smoke condensate alter their characteristics and show protective effect against cytotoxicity and HIV-1 replication

Smoking is known to exacerbate HIV-1 pathogenesis, especially in monocytes, through the oxidative stress pathway. Exosomes are known to alter HIV-1 pathogenesis through inter-cellular communication. However, the role of exosomes in smoking-mediated HIV-1 pathogenesis is unknown. In this study, we investigated the effect of cigarette smoke condensate (CSC) on the characteristics of monocyte-derived exosomes and their influence on HIV-1 replication. Initially, we demonstrated that CSC reduced total protein and antioxidant capacity in exosomes derived from HIV-1-infected and uninfected macrophages. The exosomes from CSC-treated uninfected cells showed a protective effect against cytotoxicity and viral replication in HIV-1-infected macrophages. However, exosomes derived from HIV-1-infected cells lost their protective capacity. The results suggest that the exosomal defense is likely to be more effective during the early phase of HIV-1 infection and diminishes at the latter phase. Furthermore, we showed CSC-mediated upregulation of catalase in exosomes from uninfected cells, with a decrease in the levels of catalase and PRDX6 in exosomes derived from HIV-1-infected cells. These results suggest a potential role of antioxidant enzymes, which are differentially packaged into CSC-exposed HIV-1-infected and uninfected cell-derived exosomes, on HIV-1 replication of recipient cells. Overall, our study suggests a novel role of exosomes in tobacco-mediated HIV-1 pathogenesis.

Impact of HIV infection and smoking on lung immunity and related disorders

HIV-infected persons not only have higher rates of smoking than the general population, but are also unusually vulnerable to the associated adverse health effects, both infective and noninfective in origin. Indeed, in the setting of well-organised care and availability of highly active antiretroviral therapy, HIV-infected smokers lose more life-years to smoking than to HIV infection per se, presenting a major challenge to healthcare providers. Not surprisingly, the respiratory system is particularly susceptible to the damaging interactive chronic inflammatory and immunosuppressive effects of HIV and smoking, intensifying the risk of the development of opportunistic infections, as well as lung cancer and obstructive lung disorders. The impact of smoking on the immunopathogenesis and frequencies of these respiratory conditions in the setting of HIV infection, as well as on the efficacy of antiretroviral therapy, represent the primary focus of this review.

Polycyclic aromatic hydrocarbons and cytochrome P450 in HIV pathogenesis

High prevalence of cigarette smoking in HIV patients is associated with increased HIV pathogenesis and disease progression. While the effect of smoking on the occurrence of lung cancer has been studied extensively, the association between smoking and HIV pathogenesis is poorly studied. We have recently shown the possible role of cytochrome P450 (CYP) in smoking/nicotine-mediated viral replication. In this review, we focus on the potential role of CYP pathway in polycyclic aromatic hydrocarbons (PAH), important constituents of cigarette smoke, mediated HIV pathogenesis. More specifically, we will discuss the role of CYP1A1 and CYP1B1, which are the major PAH-activating CYP enzymes. Our results have shown that treatment with cigarette smoke condensate (CSC) increases viral replication in HIV-infected macrophages. CSC contains PAH, which are known to be activated by CYP1A1 and CYP1B1 into procarcinogens/toxic metabolites. The expression of these CYPs is regulated by aryl hydrocarbon receptors (AHR), the cellular target of PAH, and an important player in various diseases including cancer. We propose that PAH/AHR-mediated CYP pathway is a novel target to develop new interventions for HIV positive smokers.

Effect of mild-to-moderate smoking on viral load, cytokines, oxidative stress, and cytochrome P450 enzymes in HIV-infected individuals

Mild-to-moderate tobacco smoking is highly prevalent in HIV-infected individuals, and is known to exacerbate HIV pathogenesis. The objective of this study was to determine the specific effects of mild-to-moderate smoking on viral load, cytokine production, and oxidative stress and cytochrome P450 (CYP) pathways in HIV-infected individuals who have not yet received antiretroviral therapy (ART). Thirty-two human subjects were recruited and assigned to four different cohorts as follows: a) HIV negative non-smokers, b) HIV positive non-smokers, c) HIV negative mild-to-moderate smokers, and d) HIV positive mild-to-moderate smokers. Patients were recruited in Cameroon, Africa using strict selection criteria to exclude patients not yet eligible for ART and not receiving conventional or traditional medications. Those with active tuberculosis, hepatitis B or with a history of substance abuse were also excluded. Our results showed an increase in the viral load in the plasma of HIV positive patients who were mild-to-moderate smokers compared to individuals who did not smoke. Furthermore, although we did not observe significant changes in the levels of most pro-inflammatory cytokines, the cytokine IL-8 and MCP-1 showed a significant decrease in the plasma of HIV-infected patients and smokers compared with HIV negative non-smokers. Importantly, HIV-infected individuals and smokers showed a significant increase in oxidative stress compared with HIV negative non-smoker subjects in both plasma and monocytes. To examine the possible pathways involved in increased oxidative stress and viral load, we determined the mRNA levels of several antioxidant and cytochrome P450 enzymes in monocytes. The results showed that the levels of most antioxidants are unaltered, suggesting their inability to counter oxidative stress. While CYP2A6 was induced in smokers, CYP3A4 was induced in HIV and HIV positive smokers compared with HIV negative non-smokers. Overall, the findings suggest a possible association of oxidative stress and perhaps CYP pathway with smoking-mediated increased viral load in HIV positive individuals.

Drug-drug interactions between anti-retroviral therapies and drugs of abuse in HIV systems

INTRODUCTION

Substance abuse is a common problem among HIV-infected individuals. Importantly, addictions as well as moderate use of alcohol, smoking, or other illicit drugs have been identified as major reasons for non-adherence to antiretroviral therapy (ART) among HIV patients. The literature also suggests a decrease in the response to ART among HIV patients who use these substances, leading to failure to achieve optimal virological response and increased disease progression.

AREAS COVERED

This review discusses the challenges with adherence to ART as well as observed drug interactions and known toxicities with major drugs of abuse, such as alcohol, smoking, methamphetamine, cocaine, marijuana, and opioids. The lack of adherence and drug interactions potentially lead to decreased efficacy of ART drugs and increased ART, and drugs of abuse-mediated toxicity. As CYP is the common pathway in metabolizing both ART and drugs of abuse, we discuss the possible involvement of CYP pathways in such drug interactions.

EXPERT OPINION

We acknowledge that further studies focusing on common metabolic pathways involving CYP and advance research in this area would help to potentially develop novel/alternate interventions and drug dose/regimen adjustments to improve medication outcomes in HIV patients who consume drugs of abuse.

Enhanced nicotine metabolism in HIV-1-positive smokers compared with HIV-negative smokers: simultaneous determination of nicotine and its four metabolites in their plasma using a simple and sensitive electrospray ionization liquid chromatography-tandem mass spectrometry technique

Smoking is approximately three times more prevalent in HIV-1-positive than HIV-negative individuals in the United States. Nicotine, which is the major constituent of tobacco, is rapidly metabolized mainly by cytochrome P450 (CYP2A6) to many metabolites. In this study, we developed a simple, fast, and sensitive electrospray ionization liquid chromatography-tandem mass spectrometry method using a strong cation solid phase extraction, and determined the concentration of nicotine and its four major metabolites (cotinine, nornicotine, norcotinine, and trans-3'-hydroxycotinine) in the plasma of HIV-1-positive and HIV-negative smokers. The multiple reaction monitoring transitions for nicotine, cotinine, trans-3'-hydroxycotinine, nornicotine, norcotinine, nicotine-d4, and cotinine-d3 were selected at mass-to-charge ratios of 163.3/117.1, 177.5/80.3, 193.2/80.1, 149.5/132.3, 163.4/80.3, 167.3/121.4, and 180.3/101.2, respectively. The lower limit of quantitation for nicotine and its metabolites was 0.53 ng/ml, which is relatively more sensitive than those previously reported. The concentration of nicotine was detected 5-fold lower in HIV-1-positive smokers (7.17 ± 3.8 ng/ml) than that observed in HIV-negative smokers (33.29 ± 15.4 ng/ml), whereas the concentration of the metabolite nornicotine was 3-fold higher in HIV-1-positive smokers (6.8 ± 2.9 ng/ml) than in HIV-negative smokers (2.3 ± 1.2 ng/ml). Although it was statistically nonsignificant, the concentration of the metabolite cotinine was also higher in HIV-1-positive smokers (85.6 ± 60.5 ng/ml) than in HIV-negative smokers (74.9 ± 40.5 ng/ml). In conclusion, a decrease in the concentration of nicotine and an increase in the concentration of its metabolites in HIV-1-positive smokers compared with HIV-negative smokers support the hypothesis that nicotine metabolism is enhanced in HIV-1-positive smokers compared with HIV-negative smokers.