Monocytes as regulators of inflammation and HIV-related comorbidities during cART

Mechanisms underlying the development of type 1 diabetes in ART-treated people living with HIV: an enigmatic puzzle

The immunopathogenesis of HIV infection remains poorly understood. Despite the widespread use of effective modern antiretroviral therapy (ART), people living with HIV (PLWH) are known to develop several comorbidities, including type 1 diabetes (T1DM). However, the etiology and critical mechanisms accounting for the onset of T1DM in the preceding context remain unknown. This article proposes to address this topic in order to provide further understanding and future research directions.

A longitudinal study of the brain structure network changes in HIV patients with ANI: combined VBM with SCN

Background

Despite the widespread adoption of combination antiretroviral therapy (cART) in managing HIV, the virus's impact on the brain structure of patients remains significant. This study aims to longitudinally explore the persistent effects of HIV on brain structure, focusing on changes in gray matter volume (GMV) and structural covariance network (SCN) among patients at the Asymptomatic Neurocognitive Impairment (ANI) stage.

Methods

This research involved 45 HIV patients diagnosed with ANI and 45 demographically matched healthy controls (HCs). The participants were observed over a 1.5-year period. Differences in GMV between groups were analyzed using voxel-based morphometry (VBM), while the graph theory model facilitated the establishment of topological metrics for assessing network indices. These differences were evaluated using two-sample t-tests and paired-sample t-tests, applying the network-based statistics method. Additionally, the study examined correlations between GMV and cognitive performance, as well as clinical variables.

Results

Compared with HCs, HIV patients demonstrated reduced GMV in the right middle temporal gyrus and left middle frontal gyrus (FWE, p < 0.05), along with decreased betweenness centrality (BC) in the left anterior cingulate and paracingulate cortex. Conversely, an increase in the clustering coefficient (Cp) was observed (FDR, p < 0.05). During the follow-up period, a decline in GMV in the right fusiform gyrus (FWE, p < 0.05) and a reduction in node efficiency (Ne) in the triangular part of the inferior frontal gyrus were noted compared with baseline measurements (FDR, p < 0.05). The SCN of HIV patients exhibited small-world properties across most sparsity levels (Sigma >1), and area under the curve (AUC) analysis revealed no significant statistical differences between groups.

Conclusion

The findings suggest that despite the administration of combination antiretroviral therapy (cART), HIV continues to exert slow and sustained damage on brain structures. However, when compared to HCs, the small-world properties of the patients' SCNs did not significantly differ, and the clustering coefficient, indicative of the overall information-processing capacity of the brain network, was slightly elevated in HIV patients. This elevation may relate to compensatory effects of brain area functions, the impact of cART, functional reorganization, or inflammatory responses.

Epigenetic modulation of myeloid cell functions in HIV and SARS-CoV-2 infection

Myeloid cells play a vital role in innate immune responses as they recognize and phagocytose pathogens like viruses, present antigens, produce cytokines, recruit other immune cells to combat infections, and contribute to the attenuation of immune responses to restore homeostasis. Signal integration by pathogen recognition receptors enables myeloid cells to adapt their functions by a network of transcription factors and chromatin remodelers. This review provides a brief overview of the subtypes of myeloid cells and the main epigenetic regulation mechanisms. Special focus is placed on the epigenomic alterations in viral nucleic acids of HIV and SARS-CoV-2 along with the epigenetic changes in the host's myeloid cell compartment. These changes are important as they lead to immune suppression and promote the progression of the disease. Finally, we highlight some promising examples of 'epidrugs' that modulate the epigenome of immune cells and could be used as therapeutics for viral infections.

The Potential of Clostridium butyricum to Preserve Gut Health, and to Mitigate Non-AIDS Comorbidities in People Living with HIV

A dramatic reduction in mortality among people living with HIV (PLWH) has been achieved during the modern antiretroviral therapy (ART) era. However, ART does not restore gut barrier function even after long-term viral suppression, allowing microbial products to enter the systemic blood circulation and induce chronic immune activation. In PLWH, a chronic state of systemic inflammation exists and persists, which increases the risk of development of inflammation-associated non-AIDS comorbidities such as metabolic disorders, cardiovascular diseases, and cancer. Clostridium butyricum is a human butyrate-producing symbiont present in the gut microbiome. Convergent evidence has demonstrated favorable effects of C. butyricum for gastrointestinal health, including maintenance of the structural and functional integrity of the gut barrier, inhibition of pathogenic bacteria within the intestine, and reduction of microbial translocation. Moreover, C. butyricum supplementation has been observed to have a positive effect on various inflammation-related diseases such as diabetes, ulcerative colitis, and cancer, which are also recognized as non-AIDS comorbidities associated with epithelial gut damage. There is currently scant published research in the literature, focusing on the influence of C. butyricum in the gut of PLWH. In this hypothesis review, we speculate the use of C. butyricum as a probiotic oral supplementation may well emerge as a potential future synergistic adjunctive strategy in PLWH, in tandem with ART, to restore and consolidate intestinal barrier integrity, repair the leaky gut, prevent microbial translocation from the gut, and reduce both gut and systemic inflammation, with the ultimate objective of decreasing the risk for development of non-AIDS comorbidities in PLWH.

Myocardial extracellular volume fraction is positively associated with activated monocyte subsets among cART-treated persons living with HIV in South Africa

BACKGROUND

Despite treatment with combination antiretroviral therapy (cART), persons living with HIV (PLWH) are at higher risk of cardiac structural abnormalities that may presage clinical heart failure, including myocardial fibrosis. This study assessed whether circulating cellular and soluble protein markers of immune activation cross-sectionally associate with myocardial fibrosis among cART-treated PLWH in South Africa.

METHODS

Participants were enrolled in Khayelitsha township near Cape Town, SA. Cardiac magnetic resonance imaging was performed. Plasma protein biomarkers were measured using enzyme-linked immunoassays and monocyte phenotypes were evaluated using flow cytometry. Associations were assessed using multivariable linear and logistic regression.

RESULTS

Among 69 cART-treated PLWH, mean (SD) age was 48 (10) years, 71% were female, and time since HIV diagnosis was 9 (6) years. Evidence of left ventricular fibrosis by late gadolinium enhancement was present in 74% of participants and mean (SD) extracellular volume fraction (ECV) was 30.9 (5.9)%. Degree of myocardial fibrosis/inflammation measured by ECV was positively associated with percentages of circulating non-classical and intermediate monocyte phenotypes reflecting inflammation and tissue injury.

CONCLUSION

These data generate hypotheses on possible immune mechanisms of HIV-associated non-ischemic myocardial disease, specifically among cART-treated PLWH in sub-Saharan Africa, where the majority of the HIV burden exists globally.

Simian immunodeficiency virus-infected rhesus macaques with AIDS co-develop cardiovascular pathology and encephalitis

Despite effective antiretroviral therapy, HIV co-morbidities remain where central nervous system (CNS) neurocognitive disorders and cardiovascular disease (CVD)-pathology that are linked with myeloid activation are most prevalent. Comorbidities such as neurocogntive dysfunction and cardiovascular disease (CVD) remain prevalent among people living with HIV. We sought to investigate if cardiac pathology (inflammation, fibrosis, cardiomyocyte damage) and CNS pathology (encephalitis) develop together during simian immunodeficiency virus (SIV) infection and if their co-development is linked with monocyte/macrophage activation. We used a cohort of SIV-infected rhesus macaques with rapid AIDS and demonstrated that SIV encephalitis (SIVE) and CVD pathology occur together more frequently than SIVE or CVD pathology alone. Their co-development correlated more strongly with activated myeloid cells, increased numbers of CD14+CD16+ monocytes, plasma CD163 and interleukin-18 (IL-18) than did SIVE or CVD pathology alone, or no pathology. Animals with both SIVE and CVD pathology had greater numbers of cardiac macrophages and increased collagen and monocyte/macrophage accumulation, which were better correlates of CVD-pathology than SIV-RNA. Animals with SIVE alone had higher levels of activated macrophage biomarkers and cardiac macrophage accumulation than SIVnoE animals. These observations were confirmed in HIV infected individuals with HIV encephalitis (HIVE) that had greater numbers of cardiac macrophages and fibrosis than HIV-infected controls without HIVE. These results underscore the notion that CNS and CVD pathologies frequently occur together in HIV and SIV infection, and demonstrate an unmet need for adjunctive therapies targeting macrophages.

The Use of CBD and Its Synthetic Analog HU308 in HIV-1-Infected Myeloid Cells

Currently, there is no cure for human immunodeficiency virus type 1 (HIV-1) infection. However, combined antiretroviral therapy (cART) aids in viral latency and prevents the progression of HIV-1 infection into acquired immunodeficiency syndrome (AIDS). cART has extended many lives, but people living with HIV-1 (PLWH) face lifelong ailments such as HIV-associated neurocognitive disorders (HAND) that range from asymptomatic HAND to HIV-1-associated dementia. HAND has been attributed to chronic inflammation and low-level infection within the central nervous system (CNS) caused by proinflammatory cytokines and viral products. These molecules are shuttled into the CNS within extracellular vesicles (EVs), lipid bound nanoparticles, and are released from cells as a form of intercellular communication. This study investigates the impact of cannabidiol (CBD), as a promising and potential therapeutic for HAND patients, and a similar synthetic molecule, HU308, on the EVs released from HIV-1-infected myeloid cells as well as HIV-1-infected 3D neurospheres. The data shows that both CBD and HU308 decrease non-coding and coding viral RNA (TAR and env) as well as proinflammatory cytokines as IL-1β and TNF-α mRNA. This decrease in viral RNA occurs in in vitro differentiated primary macrophages, in EVs released from HIV-1-infected cells monocytes, and infected neurospheres. Furthermore, a 3D neurosphere model shows an overall decrease in proinflammatory mRNA with HU308. Finally, using a humanized mouse model of HIV-1 infection, plasma viral RNA was shown to significantly decrease with HU308 alone and was most effective in combination with cART, even when compared to the typical cART treatment. Overall, CBD or HU308 may be a viable option to decrease EV release and associated cytokines which would dampen the virus spread and may be used in effective treatment of HAND in combination with cART.

Maternal ART throughout gestation prevents caudate volume reductions in neonates who are HIV exposed but uninfected

Introduction

Successful programmes for prevention of vertical HIV transmission have reduced the risk of infant HIV infection in South Africa from 8% in 2008 to below 1% in 2018/2019, resulting in an increasing population of children exposed to HIV perinatally but who are uninfected (HEU). However, the long-term effects of HIV and antiretroviral treatment (ART) exposure on the developing brain are not well understood. Whereas children who are HEU perform better than their HIV-infected counterparts, they demonstrate greater neurodevelopmental delay than children who are HIV unexposed and uninfected (HUU), especially in resource-poor settings. Here we investigate subcortical volumetric differences related to HIV and ART exposure in neonates.

Methods

We included 120 infants (59 girls; 79 HEU) born to healthy women with and without HIV infection in Cape Town, South Africa, where HIV sero-prevalence approaches 30%. Of the 79 HEU infants, 40 were exposed to ART throughout gestation (i.e., mothers initiated ART pre conception; HEU-pre), and 39 were exposed to ART for part of gestation (i.e., mothers initiated ART post conception; HEU-post). Post-conception mothers had a mean (± SD) gestational age (GA) of 15.4 (± 5.7) weeks at ART initiation. Mothers with HIV received standard care fixed drug combination ART (Tenofovir/Efavirenz/Emtricitabine). Infants were imaged unsedated on a 3T Skyra (Siemens, Erlangen, Germany) at mean GA equivalent of 41.5 (± 1.0) weeks. Selected regions (caudate, putamen, pallidum, thalamus, cerebellar hemispheres and vermis, and corpus callosum) were manually traced on T1-weighted images using Freeview.

Results

HEU neonates had smaller left putamen volumes than HUU [β (SE) = −90.3 (45.3), p = 0.05] and caudate volume reductions that depended on ART exposure duration in utero. While the HEU-pre group demonstrated no caudate volume reductions compared to HUU, the HEU-post group had smaller caudate volumes bilaterally [β (SE) = −145.5 (45.1), p = 0.002, and −135.7 (49.7), p = 0.008 for left and right caudate, respectively].

Discussion

These findings from the first postnatal month suggest that maternal ART throughout gestation is protective to the caudate nuclei. In contrast, left putamens were smaller across all HEU newborns, despite maternal ART.

The interplay among HIV, monocytes/macrophages, and extracellular vesicles: a systematic review

Despite effective antiretroviral therapies, chronic inflammation and spontaneous viral "blips" occur in HIV-infected patients. Given the roles for monocytes/macrophages in HIV pathogenesis and extracellular vesicles in intercellular communication, we performed this systematic review to delineate the triad of HIV, monocytes/macrophages, and extracellular vesicles in the modulation of immune activation and HIV activities. We searched PubMed, Web of Science, and EBSCO databases for published articles, up to 18 August 2022, relevant to this triad. The search identified 11,836 publications, and 36 studies were deemed eligible and included in this systematic review. Data were extracted for the characteristics of HIV, monocytes/macrophages, and extracellular vesicles used for experiments and the immunologic and virologic outcomes in extracellular vesicle recipient cells. Evidence for the effects on outcomes was synthesized by stratifying the characteristics by outcomes. In this triad, monocytes/macrophages were potential producers and recipients of extracellular vesicles, whose cargo repertoires and functionalities were regulated by HIV infection and cellular stimulation. Extracellular vesicles derived from HIV-infected monocytes/macrophages or the biofluid of HIV-infected patients enhanced innate immune activation and HIV dissemination, cellular entry, replication, and latency reactivation in bystander or infected target cells. These extracellular vesicles could be synthesized in the presence of antiretroviral agents and elicit pathogenic effects in a wide range of nontarget cells. At least eight functional types of extracellular vesicles could be classified based on the diverse extracellular vesicle effects, which were linked to specific virus- and/or host-derived cargos. Thus, the monocyte/macrophage-centered multidirectional crosstalk through extracellular vesicles may help sustain persistent immune activation and residual viral activities during suppressed HIV infection.

SMAD2/3 Phosphorylation Is Downregulated in T Cells in HIV-Infected Patients

Persistent inflammation contributes to the exhaustion of immune system and non-AIDS-defining events in HIV-infected patients. Transforming growth factor β (TGF-β) is generally considered an anti-inflammatory cytokine. It is unclear that why high-level TGF-β coexists with chronic inflammation during HIV infection. In this study, it was found that HIV-infected patients had lower proportion of phosphorylated SMAD2/3-positive cells among total CD3⁺ T cells and subsets of CD3⁺CD8⁺ and CD3⁺CD8^- T cells when compared with health subjects. The findings implied that phosphorylation of SMAD2/3 is inhibited in HIV-infected patients, and that disturbance of TGF-β/SMAD2/3 signaling pathway may be involved in HIV-related chronic inflammation.

Resistance to Prostaglandin E2 Promotes Monocyte Activation During Chronic HIV Infection

BACKGROUND

Monocyte activation is a driver of inflammation in the course of chronic HIV infection. Prostaglandin E2 (PGE2) is known to mediate anti-inflammatory effects, notably the inhibition of tumor necrosis factor- (TNF-) production by monocytes. We aim to investigate the effects of PGE2 on activation of monocytes in chronic HIV infection and the mechanisms through which PGE2 modulates their inflammatory signature.

METHODS

We recruited a group of people with HIV (PWH) and matched healthy uninfected persons. We compared plasma levels of PGE2, monocyte activation, and sensitivity of monocytes to the inhibitory actions mediated by PGE2.

RESULTS

We found increased plasma levels of PGE2 in PWH, and an activated phenotype in circulating monocytes, compared with uninfected individuals. Monocytes from PWH showed a significant resistance to the inhibitory actions mediated by PGE2; the concentration of PGE2 able to inhibit 50 of the production of TNF- by lipopolysaccharide-stimulated monocytes was 10 times higher in PWH compared with uninfected controls. Furthermore, the expression of phosphodiesterase 4B, a negative regulator of PGE2 activity, was significantly increased in monocytes from PWH.

CONCLUSIONS

Resistance to the inhibitory actions mediated by PGE2 could account, at least in part, for the inflammatory profile of circulating monocytes in PWH.

Trans women have worse cardiovascular biomarker profiles than cisgender men independent of hormone use and HIV serostatus

BACKGROUND

Feminizing hormonal therapy (FHT) and HIV potentially alter cardiovascular disease (CVD) risk in transgender women (TW).

METHODS

TW were enrolled in Los Angeles, California and Houston, Texas and frequency-matched to Multicenter AIDS Cohort Study cisgender men (CM) on age, race, substance use, and abacavir use. Biomarkers of CVD risk and inflammation were assessed via ELISA. Wilcoxon rank sum and Fisher's exact tests compared TW and CM. Multivariable linear regression assessed factors associated with biomarker concentrations.

RESULTS

TW (HIV+ n  = 75, HIV- n  = 47) and CM (HIV+ n  = 40, HIV- n  = 40) had mean age 43-45 years; TW/CM were 90%/91% non-Hispanic Black, Hispanic, or Multiracial, 26%/53% obese, and 34%/24% current smokers; 67% of TW were on FHT. Among people with HIV (PWH), TW had higher median extracellular newly-identified receptor for advanced glycation end-products (EN-RAGE), lipoprotein-associated phospholipase A2 (LpPLA2), oxidized low-density lipoprotein (oxLDL), soluble tumor necrosis factor receptor type (sTNFR) I/II, interleukin (IL)-8 and plasminogen activator inhibitor (PAI)-1, but lower soluble CD14, von Willebrand factor (vWF) and endothelin (ET)-1 levels than CM. Findings were similar for participants without HIV (all P  < 0.05). In multivariable analysis, TW had higher EN-RAGE, IL-6, IL-8, P selectin, PAI-1, oxLDL and sTNFRI/II concentrations, and lower vWF, independent of HIV serostatus and current FHT use. Both being a TW and a PWH were associated with lower ET-1.

CONCLUSIONS

Compared to matched cisgender men, trans women have altered profiles of biomarkers associated with systemic inflammation and CVD. Further work is needed to decipher the contributions of FHT to CVD risk in TW with HIV.

Buprenorphine reverses neurocognitive impairment in EcoHIV infected mice: A potential therapy for HIV-NCI

Thirty-eight million people worldwide are living with HIV, PWH, a major public health problem. Antiretroviral therapy (ART) revolutionized HIV treatment and significantly increased the lifespan of PWH. However, approximately 15-50% of PWH develop HIV associated neurocognitive disorders (HIV-NCI), a spectrum of cognitive deficits, that negatively impact quality of life. Many PWH also have opioid use disorder (OUD), and studies in animal models of HIV infection as well as in PWH suggest that OUD can contribute to HIV-NCI. The synthetic opioid agonist, buprenorphine, treats OUD but its effects on HIV-NCI are unclear. We reported that human mature inflammatory monocytes express the opioid receptors MOR and KOR, and that buprenorphine reduces important steps in monocyte transmigration. Monocytes also serve as HIV reservoirs despite effective ART, enter the brain, and contribute to HIV brain disease. Using EcoHIV infected mice, an established model of HIV infection and HIV-NCI, we previously showed that pretreatment of mice prior to EcoHIV infection reduces mouse monocyte entry into the brain and prevents NCI. Here we show that buprenorphine treatment of EcoHIV infected mice with already established chronic NCI completely reverses the disease. Disease reversal was associated with a significant reduction in brain inflammatory monocytes and reversal of dendritic injury in the cortex and hippocampus. These results suggest that HIV-NCI persistence may require a continuing influx of inflammatory monocytes into the brain. Thus, we recommend buprenorphine as a potential therapy for mitigation of HIV brain disease in PWH with or without OUD.

Navigating the complexity of chronic HIV-1 associated immune dysregulation

Despite successful viral suppression with antiretroviral therapy, chronic HIV-1 infection is associated with ongoing immune dysfunction. Investigation of the complex immune response in treated and untreated individuals with chronic HIV-1 infection is warranted. Immune alterations such as monocyte phenotype and Th-17/Treg ratios often persist years after the reduction in viraemia and predispose many individuals to long-term comorbidities such as cardiovascular disease or cancer. Furthermore, while there has been extensive research on the latent reservoir of treated patients with chronic HIV-1, which prevents the discontinuation of treatment, the mechanism behind this remains elusive and needs further investigation. In this review, we assist in navigating the recent research on these groups of individuals and provide a basis for further investigation.

Monocyte count and soluble markers of monocyte activation in people living with HIV and uninfected controls

Background

Monocytes play an important role in inflammation, and monocytosis and monocyte activation are features of chronic inflammation. We aimed to investigate if HIV status was associated with monocyte count and monocyte activation and to assess the relationship between monocyte count and monocyte activation markers and HIV-related factors.

Methods

Persons living with HIV (PLWH) with measured monocyte count and sCD14 and sCD163 were included from the Copenhagen Comorbidity in HIV infection (COCOMO) study and matched 1:5 on sex and age with uninfected controls. In addition, 74 uninfected individuals from COCOMO with measured sCD14 and sCD163 were included. Identical protocols and equipment were used to determine monocyte counts and monocyte activation in PLWH and uninfected controls. Linear regression adjusted for age, sex, smoking and waist-to-hip-ratio was used to analyze the association between possible risk factors and monocyte outcomes.

Results

We included 871 PLWH and 4355 uninfected controls. PLWH had − 0.021 [− 0.031 − 0.011] × 10⁹/L) lower monocyte count than uninfected controls, and in adjusted analyses HIV status was independently associated with − 0.035 [− 0.045, − 0.025] × 10⁹/L lower monocyte count. In contrast, PLWH had higher sCD163 and sCD14 concentrations than uninfected controls. After adjustment, HIV-status was associated with higher sCD14 and sCD163 concentrations (588 [325, 851] ng/ml, and 194 [57, 330] ng/ml, respectively).

Conclusion

PLWH had lower monocyte counts than controls, but the absolute difference was small, and any clinical impact is likely limited. In contrast, concentrations of monocyte activation markers, previously implicated as drivers of non-AIDS comorbidity, were higher in PLWH than in controls.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07450-y.

NMDA receptor antagonists engender neuroprotection against gp120-induced cognitive dysfunction in Rats through Modulation of PKR activation, oxidative stress, ER stress and IRE1α Signal Pathway

It is widely accepted that the surface glycoprotein (gp120) of human immunodeficiency virus-1 (HIV-1) plays an important role in HIV-1-induced nerve damage and pathogenesis of HIV-associated neurocognitive disorders (HAND). Our previous work has demonstrated that gp120 enhanced excitatory postsynaptic currents (EPSCs) mediated by N-methyl-D-aspartate receptors (NMDARs) and caused neural injury. However, the relationship between gp120, NMDARs and HAND is still unclear. Several lines of evidence indicate that double-stranded RNA-activated protein kinase (PKR) is involved in NMDA-induced cerebral ischemia and retinal damage, but because its role in neuropathology is still debated, we examined whether PKR links oxidative stress and endoplasmic reticulum (ER) stress to exert a deleterious role in the rat model with gp120 induced dementia. In this study, we found that NMDAR antagonist memantine or PKR inhibitor C16 improved gp120-induced learning and memory impairment, and inhibited gp120-induced PKR activity. Furthermore, memantine or C16 was found to attenuate gp120-inducd neuroinflammation, oxidative stress, ER stress and its downstream IRE1α/JNK pathway. Additionally, memantine or C16 evidently inhibited apoptotic pathways by reducing the Bax and caspase-3, 8, 9 expressions and increasing Bcl-2 expression. So the NMDA receptor antagonists could alleviate HIV/gp120 induced dementia in the rat model by altering PKR level. In conclusion, this study demonstrates that NMDARs plays a key role in HIV/gp120 induced hippocampal damage and cognitive dysfunction through PKR mediated oxidative stress, ER stress, and IRE1α/JNK signaling pathway in rats, implicating PKR inhibitors could provide a novel neuroprotective strategy for HAND via inhibiting ER stress and its downstream IRE1α signaling pathway.

Peripheral blood CD4+CCR6+ compartment differentiates HIV-1 infected or seropositive elite controllers from long-term successfully treated individuals

HIV-1 infection induces a chronic inflammatory environment not restored by suppressive antiretroviral therapy (ART). As of today, the effect of viral suppression and immune reconstitution in people living with HIV-1 (PLWH) has been well described but not completely understood. Herein, we show how PLWH who naturally control the virus (PLWH_EC) have a reduced proportion of CD4⁺CCR6⁺ and CD8⁺CCR6⁺ cells compared to PLWH on suppressive ART (PLWH_ART) and HIV-1 negative controls (HC). Expression of CCR2 was reduced on both CD4⁺, CD8⁺ and classical monocytes in PLWH_EC compared to PLWH_ART and HC. Longer suppressive therapy, measured in the same patients, decreased number of cells expressing CCR2 on all monocytic cell populations while expression on CD8⁺ T cells increased. Furthermore, the CD4⁺CCR6⁺/CCR6^- cells exhibited a unique proteomic profile with a modulated energy metabolism in PLWH_EC compared to PLWH_ART independent of CCR6 status. The CD4⁺CCR6⁺ cells also showed an enrichment in proteins involved in apoptosis and p53 signalling in PLWH_EC compared to PLWH_ART, indicative of increased sensitivity towards cell death mechanisms. Collectively, this data shows how PLWH_EC have a unique chemokine receptor profile that may aid in facilitating natural control of HIV-1 infection.

Chronic Alcohol Exposure Among People Living with HIV Is Associated with Innate Immune Activation and Alterations in Monocyte Phenotype and Plasma Cytokine Profile

Despite advances in antiretroviral therapy, chronic immune activation continues to be observed among individuals with well-controlled HIV viral loads, and is associated with non-AIDS defining morbidities among people living with HIV. Alcohol use disorder impacts a significant proportion of individuals living with HIV, and alcohol exposure is known to damage the intestinal epithelium which may increase translocation of pathogens and their molecular products, driving systemic immune activation and dysregulation. The aim of this study was to determine if adults living with HIV with well-controlled viral loads, who also suffer from alcohol use disorder with and without hepatitis C virus co-infection (n=23), exhibit evidence of advanced systemic immune activation, intestinal damage, and microbial translocation, as compared to adults living with HIV who are not exposed to chronic alcohol or other substances of abuse (n=29). The impact of a 1-month intervention to treat alcohol-use disorder was also examined. Alcohol-use disorder was associated with evidence of advanced innate immune activation, alterations in monocyte phenotype including increased expression of Toll-like receptor 4, increased burden of stimulatory ligands for Toll-like receptor 4, and alterations in plasma cytokine signature, most notably elevations in soluble CD40 ligand and transforming growth factor beta. Alcohol-associated immune activation was more pronounced among individuals with hepatitis C virus co-infection. Although the 1-month intervention to treat alcohol use disorder did not result in significant reductions in the interrogated indicators of immune activation, our findings suggest that chronic alcohol exposure is a major modifiable risk factor for chronic immune activation and dysregulation among people-living with HIV.

ApoA-I mimetics reduce systemic and gut inflammation in chronic treated HIV

Novel therapeutic strategies are needed to attenuate increased systemic and gut inflammation that contribute to morbidity and mortality in chronic HIV infection despite potent antiretroviral therapy (ART). The goal of this study is to use preclinical models of chronic treated HIV to determine whether the antioxidant and anti-inflammatory apoA-I mimetic peptides 6F and 4F attenuate systemic and gut inflammation in chronic HIV. We used two humanized murine models of HIV infection and gut explants from 10 uninfected and 10 HIV infected persons on potent ART, to determine the in vivo and ex vivo impact of apoA-I mimetics on systemic and intestinal inflammation in HIV. When compared to HIV infected humanized mice treated with ART alone, mice on oral apoA-I mimetic peptide 6F with ART had consistently reduced plasma and gut tissue cytokines (TNF-α, IL-6) and chemokines (CX3CL1) that are products of ADAM17 sheddase activity. Oral 6F attenuated gut protein levels of ADAM17 that were increased in HIV-1 infected mice on potent ART compared to uninfected mice. Adding oxidized lipoproteins and endotoxin (LPS) ex vivo to gut explants from HIV infected persons increased levels of ADAM17 in myeloid and intestinal cells, which increased TNF-α and CX3CL1. Both 4F and 6F attenuated these changes. Our preclinical data suggest that apoA-I mimetic peptides provide a novel therapeutic strategy that can target increased protein levels of ADAM17 and its sheddase activity that contribute to intestinal and systemic inflammation in treated HIV. The large repertoire of inflammatory mediators involved in ADAM17 sheddase activity places it as a pivotal orchestrator of several inflammatory pathways associated with morbidity in chronic treated HIV that make it an attractive therapeutic target.

A Sex-Stratified Analysis of Monocyte Phenotypes Associated with HIV Infection in Uganda

Women with HIV may experience higher rates of non-AIDS comorbidities compared to men with HIV, but the underlying mechanisms are not well understood. We investigated sex-related differences in the effects of HIV on monocyte phenotypes within the Ugandan Study of HIV effects on the Myocardium and Atherosclerosis (mUTIMA). Of 133 participants who provided blood for flow cytometry assays, 86 (65%) were women and 91 (68%) were persons living with HIV (PLWH) on antiretroviral therapy. The median age was 57 (interquartile range, 52–63) years. PLWH exhibited a lower proportion of circulating CD14⁺CD16^- classical monocytes (66.3% vs. 75.1%; p < 0.001), and higher proportion of CD14⁺CD16⁺ inflammatory monocytes (17% vs. 11.7%; p = 0.005) compared to HIV-uninfected participants. PLWH had an increased expression of the chemokine receptor CX3CR1 in total monocytes (CX3CR1⁺ monocytes, 24.5% vs. 4.7%; p < 0.001) and monocyte subsets. These findings were generally similar when analyzed by sex, with no significant interactions between sex and HIV status in adjusted models. Our data show that the inflammatory monocyte subset is expanded and monocyte CX3CR1 chemokine receptor expression is enhanced among PLWH, regardless of sex. Whether these parameters differentially affect risk for non-AIDS comorbidities and clinical outcomes in women with HIV requires additional investigation.

Acute HIV-1 and SARS-CoV-2 Infections Share Slan+ Monocyte Depletion-Evidence from an Hyperacute HIV-1 Case Report

Monocytes are key modulators in acute viral infections, determining both inflammation and development of specific B- and T-cell responses. Recently, these cells were shown to be associated to different SARS-CoV-2 infection outcome. However, their role in acute HIV-1 infection remains unclear. We had the opportunity to evaluate the mononuclear cell compartment in an early hyper-acute HIV-1 patient in comparison with an untreated chronic HIV-1 and a cohort of SARS-CoV-2 infected patients, by high dimensional flow cytometry using an unsupervised approach. A distinct polarization of the monocyte phenotype was observed in the two viral infections, with maintenance of pro-inflammatory M1-like profile in HIV-1, in contrast to the M2-like immunosuppressive shift in SARS-CoV-2. Noticeably, both acute infections had reduced CD14^low/−CD16⁺ non-classical monocytes, with depletion of the population expressing Slan (6-sulfo LacNac), which is thought to contribute to immune surveillance through pro-inflammatory properties. This depletion indicates a potential role of these cells in acute viral infection, which has not previously been explored. The inflammatory state accompanied by the depletion of Slan+ monocytes may provide new insights on the critical events that determine the rate of viral set-point in acute HIV-1 infection and subsequent impact on transmission and reservoir establishment.

Neuroinflammatory profiles regulated by the redox environment predicted cognitive dysfunction in people living with HIV: A cross-sectional study

BACKGROUND

Despite effective combination antiretroviral therapy (cART), people living with HIV (PLWH) remain at risk for developing neurocognitive impairment primarily due to systemic inflammation that persists despite virologic suppression, albeit the mechanisms underlying such inflammation are poorly understood.

METHODS

Herein, we evaluate the predictive capacity of the mitochondrial redox environment on circulating neuro- and T-lymphocyte-related inflammation and concomitant cognitive function in 40 virally-suppressed PLWH and 40 demographically-matched controls using structural equation modeling. We used state-of-the-art systems biology approaches including Seahorse Analyzer of mitochondrial function, electron paramagnetic resonance (EPR) spectroscopy to measure superoxide levels, antioxidant activity assays, and Meso Scale multiplex technology to quantify inflammatory proteins in the periphery.

FINDINGS

We observed disturbances in mitochondrial function and the redox environment in PLWH compared to controls, which included reduced mitochondrial capacity (t(76) = -1.85, p = 0.034, 95% CI: -∞,-0.13), elevated levels of superoxide (t(75) = 1.70, p = 0.047, 95% CI: 8.01 E 3, ∞) and alterations in antioxidant defense mechanisms (t(74) = 1.76, p = 0.041, 95% CI: -710.92, ∞). Interestingly, alterations in both superoxide- and hydrogen peroxide-sensitive redox environments were differentially predictive of neuro-, but not T-lymphocyte-related inflammatory profiles in PLWH and controls, respectively (ps < 0.026). Finally, when accounting for superoxide-sensitive redox pathways, neuroinflammatory profiles significantly predicted domain-specific cognitive function across our sample (β = -0.24, p = 0.034, 95% CI: -0.09, -0.004 for attention; β = -0.26, p = 0.018, 95% CI: -0.10, -0.01 for premorbid function).

INTERPRETATION

Our results suggest that precursors to neuroinflammation apparent in PLWH (i.e., mitochondrial function and redox environments) predict overall functionality and cognitive dysfunction and importantly, may serve as a proxy for characterizing inflammation-related functional decline in the future.

FUNDING

National Institute of Mental Health, National Institute for Neurological Disorders and Stroke, National Institute on Drug Abuse, National Science Foundation.

SARS-CoV-2 Portrayed against HIV: Contrary Viral Strategies in Similar Disguise

SARS-CoV-2 and HIV are zoonotic viruses that rapidly reached pandemic scale, causing global losses and fear. The COVID-19 and AIDS pandemics ignited massive efforts worldwide to develop antiviral strategies and characterize viral architectures, biological and immunological properties, and clinical outcomes. Although both viruses have a comparable appearance as enveloped viruses with positive-stranded RNA and envelope spikes mediating cellular entry, the entry process, downstream biological and immunological pathways, clinical outcomes, and disease courses are strikingly different. This review provides a systemic comparison of both viruses' structural and functional characteristics, delineating their distinct strategies for efficient spread.

Descriptive modification of inflammatory markers in HIV patients after cART initiation according to gender, smoking habit, CMV infection, BMI and serum lipids

Persistent inflammation, despite anti-retroviral therapy (ART), is an independent predictor of mortality and comorbidities in HIV infection. Multiple factors, including lifestyle and chronic viral coinfections, may contribute. Several of these factors are also associated with a chronic inflammation in the general population. Little is known about the degree to which these factors influence inflammation in HIV infection, particularly within the first year of ART. The purpose of this study was to distinguish the effects of factors (gender, body mass index, cholesterol and triglyceride levels, smoke habit and cytomegalovirus seropositivity), known to contribute to inflammation, on inflammation biomarkers over the first year of ART in HIV-infected patients. Linear mixed model analysis revealed significant biomarker decreases [soluble CD14 (s-CD14), soluble CD163 (s-CD163) and D-dimer (DD)], or increases [C Reactive Protein (CRP) and interleukin-6 (IL-6)] over time in the whole cohort, differences in most categories (genders for IL-6, smoke habit for s-CD14, cytomegalovirus infection for s-CD163 and IL-6) and in some category × time interactions [gender for interleukin-7 (IL-7)], cytomegalovirus infection for s-CD14 and cholesterol levels for s-CD14 and Tumor Necrosis Factor α (TNF-α)]. This explorative longitudinal study suggests further investigations on targeting inflammation pathophysiology in HIV-infected patients on ART.

Differential recognition of HIV-stimulated IL-1β and IL-18 secretion through NLR and NAIP signalling in monocyte-derived macrophages

Macrophages are important drivers of pathogenesis and progression to AIDS in HIV infection. The virus in the later phases of the infection is often predominantly macrophage-tropic and this tropism contributes to a chronic inflammatory and immune activation state that is observed in HIV patients. Pattern recognition receptors of the innate immune system are the key molecules that recognise HIV and mount the inflammatory responses in macrophages. The innate immune response against HIV-1 is potent and elicits caspase-1-dependent pro-inflammatory cytokine production of IL-1β and IL-18. Although, NLRP3 has been reported as an inflammasome sensor dictating this response little is known about the pattern recognition receptors that trigger the “priming” signal for inflammasome activation, the NLRs involved or the HIV components that trigger the response. Using a combination of siRNA knockdowns in monocyte derived macrophages (MDMs) of different TLRs and NLRs as well as chemical inhibition, it was demonstrated that HIV Vpu could trigger inflammasome activation via TLR4/NLRP3 leading to IL-1β/IL-18 secretion. The priming signal is triggered via TLR4, whereas the activation signal is triggered by direct effects on Kv1.3 channels, causing K⁺ efflux. In contrast, HIV gp41 could trigger IL-18 production via NAIP/NLRC4, independently of priming, as a one-step inflammasome activation. NAIP binds directly to the cytoplasmic tail of HIV envelope protein gp41 and represents the first non-bacterial ligand for the NAIP/NLRC4 inflammasome. These divergent pathways represent novel targets to resolve specific inflammatory pathologies associated with HIV-1 infection in macrophages.

It has been previously shown that inflammasome activation can be triggered during viral infection to produce the active cytokines IL-1β and IL-18. Our study represents a significant advance, as we now show that in fact there are distinct NLR inflammasome complexes and viral ligands for IL-1β secretion (Vpu) compared to IL-18 secretion (gp41) in response to HIV-1.

Most importantly, we show that the HIV envelope protein gp41 represents the first non-bacterial ligand for the assembly of the NAIP/NLRC4 inflammasome. HIV gp41 is a viroporin, and thus our data demonstrates for the first time that the NAIP/NLRC4 inflammasome assembles for all pore-forming proteins, irrespective of whether they have a viral or bacterial origin. This is critical for the host antiviral response and has broad implications for innate immunity in general.

Immunomodulation by cannabinoids: Current uses, mechanisms, and identification of data gaps to be addressed for additional therapeutic application

The endocannabinoid system plays a critical role in immunity and therefore its components, including cannabinoid receptors 1 and 2 (CB₁ and CB₂), are putative druggable targets for immune-mediated diseases. Whether modulating endogenous cannabinoid levels or interacting with CB₁ or CB₂ receptors directly, cannabinoids or cannabinoid-based therapeutics (CBTs) show promise as anti-inflammatory or immune suppressive agents. Herein we provide an overview of cannabinoid effects in animals and humans that provide support for the use of CBTs in immune-mediated disease such as multiple sclerosis (MS), inflammatory bowel disease (IBD), asthma, arthritis, diabetes, human immunodeficiency virus (HIV), and HIV-associated neurocognitive disorder (HAND). This is not an exhaustive review of cannabinoid effects on immune responses, but rather provides: (1) key studies in which initial and/or novel observations were made in animal studies; (2) critical human studies including meta-analyses and randomized clinical trials (RCTs) in which CBTs have been assessed; and (3) evidence for the role of CB₁ or CB₂ receptors in immune-mediated diseases through genetic analyses of single nucleotide polymorphisms (SNPs) in the CNR1 and CNR2 genes that encode CB₁ or CB₂ receptors, respectively. Perhaps most importantly, we provide our view of data gaps that exist, which if addressed, would allow for more rigorous evaluation of the efficacy and risk to benefit ratio of the use of cannabinoids and/or CBTs for immune-mediated diseases.

Cryptococcal Immune Reconstitution Inflammatory Syndrome: From Blood and Cerebrospinal Fluid Biomarkers to Treatment Approaches

Immune reconstitution inflammatory syndrome (IRIS) presents as an exaggerated immune reaction that occurs during dysregulated immune restoration in immunocompromised patients in late-stage human immunodeficiency virus (HIV) infection who have commenced antiretroviral treatments (ART). Virtually any opportunistic pathogen can provoke this type of immune restoration disorder. In this review, we focus on recent developments in the identification of risk factors for Cryptococcal IRIS and on advancements in our understanding of C-IRIS immunopathogenesis. We overview new findings in blood and cerebrospinal fluid which can potentially be useful in the prediction and diagnosis of cryptococcal meningitis IRIS (CM-IRIS). We assess current therapeutic regimens and novel treatment approaches to combat CM-IRIS. We discuss the utility of biomarkers for clinical monitoring and adjusting treatment modalities in acquired immunodeficiency syndrome (AIDS) patients co-infected with Cryptococcus who have initiated ART.

Monocyte/Macrophage-Mediated Innate Immunity in HIV-1 Infection: From Early Response to Late Dysregulation and Links to Cardiovascular Diseases Onset

Although monocytes and macrophages are key mediators of the innate immune system, the focus has largely been on the role of the adaptive immune system in the context of human immunodeficiency virus (HIV) infection. Thus more attention and research work regarding the innate immune system-especially the role of monocytes and macrophages during early HIV-1 infection-is required. Blood monocytes and tissue macrophages are both susceptible targets of HIV-1 infection, and the early host response can determine whether the nature of the infection becomes pathogenic or not. For example, monocytes and macrophages can contribute to the HIV reservoir and viral persistence, and influence the initiation/extension of immune activation and chronic inflammation. Here the expansion of monocyte subsets (classical, intermediate and non-classical) provide an increased understanding of the crucial role they play in terms of chronic inflammation and also by increasing the risk of coagulation during HIV-1 infection. This review discusses the role of monocytes and macrophages during HIV-1 pathogenesis, starting from the early response to late dysregulation that occurs as a result of persistent immune activation and chronic inflammation. Such changes are also linked to downstream targets such as increased coagulation and the onset of cardiovascular diseases.

Utilization of absolute monocyte counts to predict cardiovascular events in people living with HIV

OBJECTIVES

Cardiovascular risk is increased in people living with HIV (PLWH). In HIV-uninfected populations, total absolute monocyte count (AMC) has been shown to be predictive of future cardiovascular events (CVEs). We sought to determine whether AMC predicts CVEs in PLWH independent of established and HIV-related cardiovascular risk factors.

METHODS

We identified all PLWH within the Partners HIV Cohort without factors that could confound the monocyte count. CVE was defined as fatal or non-fatal acute myocardial infarction or ischaemic stroke. Baseline-measured AMC was defined as the average of all outpatient AMC counts a year before and after the baseline date. Multivariable Cox proportional hazards models were used to assess the association of baseline AMC with CVEs.

RESULTS

Our cohort consisted of 1980 patients, with median follow-up of 10.9 years and 182 CVEs. Mean (± SD) age was 41.9 ± 9.3 years; 73.0% were male. Mean CD4 count was 506.3 ± 307.1 cells/µL, 48% had HIV viral load (VL) < 400 copies/mL, and 87% were on antiretroviral therapy. Mean AMC was 0.38 × 10³  ± 0.13 cells/µL. In multivariable modelling adjusted for traditional CV risk factors, CD4 cell count, and HIV VL, AMC quartile 2 (Q2) (HR = 1.01, P = 0.98), Q3 (HR = 1.07, P = 0.76), and Q4 (HR = 0.97, P = 0.89) were not significantly predictive of CVE compared with Q1.

DISCUSSION

Baseline AMC was not associated with long-term CVEs in PLWH. AMC obtained in routine clinical encounters does not appear to enhance CV risk stratification in PLWH.

TLR agonists enhance responsiveness of inflammatory innate immune cells in HLA-B*57-positive HIV patients

Abstract

HLA-B*57 affects the course of HIV infection. Under antiretroviral therapy, its effects cannot be explained by outstandingly efficient T cell responses alone but may also involve cells of innate immunity. Studying in vitro stimulation with Pam3CSK4, E. coli LPS-B5 and CpG-ODN-2216, we observed greater induction of IL-6/IL-1beta double-positive CD14⁺CD16⁺⁺ monocytes as well as IFN-gamma-positive cytotoxic CD56^highCD16^neg NK cells in HLA-B*57- versus HLA-B*44-positive HIV patients, while TNF-alpha induction remained unchanged. Differences were not seen in the other monocyte and NK cell subsets or in HLA-matched healthy controls. Our findings show that, in virally suppressed HIV infection, HLA-B*57 is associated with enhanced responsiveness of inflammatory innate immune cells to TLR ligands, possibly contributing to increased vulnerability in sepsis.

Key messages

• HLA-B*57 is a host factor affecting clinical outcomes of HIV infection.

• HLA-B*57 modifies inflammatory subsets of NK cells and monocytes in HIV infection.

• In HLA-B*57-positive HIV patients TLR agonists induce enhanced IL-6/IL-1beta in monocytes.

• NK cells from HLA-B*57 HIV patients release more IFN-gamma upon TLR costimulation.

• HLA-B*57 is linked to enhanced inflammatory responsiveness to TLR ligands.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00109-020-01996-7.

Targeting Cannabinoid Receptor 2 on Peripheral Leukocytes to Attenuate Inflammatory Mechanisms Implicated in HIV-Associated Neurocognitive Disorder

HIV infection affects an estimated 38 million people. Approximately 50% of HIV patients exhibit neurocognitive dysfunction termed HIV-Associated Neurocognitive Disorder (HAND). HAND is a consequence of chronic low-level neuroinflammation due to HIV entry into the brain. Initially, monocytes become activated in circulation and traffic to the brain. Monocytes, when activated, become susceptible to infection by HIV and can then carry the virus across the blood brain barrier. Once in the brain, activated monocytes secrete chemokines, which recruit virus-specific CD8+ T cells into the brain to further promote neuroinflammation. HAND is closely linked to systemic inflammation driven, in part, by HIV but is also due to persistent translocation of microorganisms across the GI tract. Persistent anti-viral responses in the GI tract compromise microbial barrier integrity. Indeed, HIV patients can exhibit remarkably high levels of activated (CD16+) monocytes in circulation. Recent studies, including our own, show that HIV patients using medical marijuana exhibit lower levels of circulating CD16+ monocytes than non-cannabis using HIV patients. Cannabis is a known immune modulator, including anti-inflammatory properties, mediated, in part, by ∆9-tetrahydrocannabinol (THC), as well as less characterized minor cannabinoids, such as cannabidiol (CBD), terpenes and presumably other cannabis constituents. The immune modulating activity of THC is largely mediated through cannabinoid receptors (CB) 1 and 2, with CB1 also responsible for the psychotropic properties of cannabis. Here we discuss the anti-inflammatory properties of cannabinoids in the context of HIV and propose CB2 as a putative therapeutic target for the treatment of neuroinflammation. Graphical Abstract HIV-associated neurocognitive disorder is a systemic inflammatory disease leading to activation of plasmacytoid dendritic cells, monocytes and T cells. Monocyte and CD8 T cell migration across the BBB and interaction with astrocytes promotes neurotoxic inflammatory mediators release. CB2 ligands are proposed as therapeutics capable of suppressing systemic and localized inflammation.

[The study of the innate and acquired cellular immunity chains indicators in the peripheral blood of patients with HIV infection.]

In this study was made an attempt to reveal additional laboratory markers of white blood for preliminary estimation level of HIV-infection development. Essentially such markers these are in progress without complex equipment and expensive reagent. It was studied alterations of basic values cells of innate and acquired immunity of peripheral blood HIV-infected individuals with and without antiretroviral treatment (ART) during infection. It was estimate value leukocytes, neutrophils, monocytes, lymhpocytes, T-lymhpocytes, CD₄⁺, CD₈⁺ T-cells, CD₄/CD₈ index. It was used the first analysis in the time of registration for regular medical check-up and the intermediate derived during 2017-2018 years. Patients without ART and with ART before and after treatment had rates of leukocytes, lymhpocytes, T-lymhpocytes, monocytes and neutrophils within the normal guideline. Essential changes were observed in basic conventional laboratory parameters evaluation of HIV-infection dynamic (parameters of CD₄⁺, CD₈⁺ T-cells, CD₄/CD₈ index). Thereby it was impossible to reveal supplementary immunological markers of HIVinfection.

A longitudinal study of brain volume changes in rhesus macaque model infected with SIV

Given the current lack of understanding of brain volume changes caused by HIV infection, this study aimed to longitudinally assess the changes in regional brain tissue volume following HIV infection and to explore its relationship with peripheral blood absolute CD4+ lymphocyte count (CD4+), the percentage of monocytes in plasma(MON%) and cerebrospinal fluid viral load (CFVL).Four adult male rhesus monkeys were examined in healthy status and following infection with simian immunodeficiency virus using high-resolution 3D T1-weighted sagittal whole brain magnetic resonance imaging. DPABI and SPM were used to process and record changes in brain tissue volume. Correlation analyses were then used to explore the above relationships. Compared with brain tissue volume during the healthy stage, there was no change at 12 and 24 weeks postinoculation (12 wpi, 24 wpi). At 36 wpi, 48 wpi, and 60 wpi, basal ganglia, left inferior temporal gyrus, left occipital gyrus, and left superior frontal gyrus exhibited varying degrees of atrophy. There was no association found between CD4+, MON%, CFVL, and brain volume loss in any brain region. Our research demonstrated that in the early stage of HIV infection, local brain tissue atrophy can be demonstrated by MRI technique; furthermore, MRI can identify the earliest site of atrophy as well as the most severely affected site. Although there was no significant correlation between brain tissue volume loss and CD4+, MON%, and CFVL, our findings provided some evidence in the application of volumetric MR imaging in the early diagnosis and treatment follow-up of patients with HIV infection.

Chemokine CCL2 impairs spatial memory and cognition in rats via influencing inflammation, glutamate metabolism and apoptosis-associated genes expression- a potential mechanism for HIV-associated neurocognitive disorder

AIMS

To explore the role of chemokine CC motif ligand 2 (CCL2) in spatial memory and cognition impairment, and the underlying mechanisms focused on inflammatory, glutamate metabolistic and apoptotic- associated mRNA expression.

MATERIALS AND METHODS

Stereotaxic surgery was performed here to establish a rat model by bilateral intra-hippocampal injection of CCL2. Morris water maze (MWM) and Novel object recognition test (NORT) were used to assess the learning, memory and cognitive ability respectively. RT-PCR was used to detect the relative mRNA expression of inflammatory, glutamate metabolistic and apoptotic- associated indexes. Nissl and TUNEL staining were performed to observe the morphological changes of hippocampal CA1 zone and quantified the apoptosis of hippocampal neurons of CA1 zones respectively.

KEY FINDINGS

We found CCL2 injured cognitive function in rats. Six days after CCL2 injection, we revealed the following obvious mRNA expression changes: (1) increasing of the neuroinflammatory cytokines IL-1β, CXCL-10, IL-6; (2) decreasing of the glutamate transporters GLT-1 and GLAST and increasing of PAG; (3) increasing of the apoptotic genes caspase-8, caspase-3 and Bax, while decreasing the anti-apoptotic gene Bcl-2. Further, Nissl staining and TUNEL confirmed the injury of the structure of hippocampal CA1 zones and the apoptosis of hippocampal neurons.

SIGNIFICANCE

Our results indicated that CCL2 impaired spatial memory and cognition, the involving mechanisms may link to the up-regulation of mRNA expression of the three major pathological events: inflammation, excitotoxicity and neuronal apoptosis, which were involved in HIV-associated neurocognitive disorder (HAND). Taken together, these findings suggest a potential therapeutic strategy against CCL2.

Myeloid Cells Enriched for a Dendritic Cell Population From People Living With HIV Have Altered Gene Expression Not Restored by Antiretroviral Therapy

Antiretroviral therapy (ART) for human immunodeficiency virus (HIV) infections has been designed to optimize CD4 T-cell survival and limit HIV replication. Cell types other than CD4 T cells such as monocytes/macrophage, dendritic cells, and granulocytes (collectively known as myeloid cells), are generally not considered in the development of ART protocols. Myeloid dendritic cells (mDCs) are the most potent inducers of CD4 T-cell activation and central to the regulation of immune responses. mDCs in the blood are decreased in number, altered in function, and implicated in promoting HIV latency in people living with HIV (PLWH). We found that cells enriched for mDC in PLWH had transcriptional changes compared to mDC from HIV uninfected individuals, some of which were not completely restored by ART. In contrast, other mDC functions such as interleukin-1 signaling and type I interferon pathways were restored by ART. Some of the transcriptional changes in mDC not completely reversed by ART were enriched in genes that are classically associated with cells of the monocyte/macrophage lineage, but new single-cell RNA sequencing studies show that they are also expressed by a subset of mDC. A cellular enzyme, acyloxyacyl hydrolase (AOAH), important for lipopolysaccharide (LPS) detoxification, had increased transcription in mDC of PLWH, not restored by ART. It is possible that one reason ART is not completely successful in PLWH is the failure to phenotypically change the mDCs. Thus, inability of ART to be completely effective might involve myeloid cells and the failure to restore mDC function as measured by gene transcription. We suggest that mDC and myeloid cells should be considered in future combination ART development.

Altered monocyte phenotype and dysregulated innate cytokine responses among people living with HIV and opioid-use disorder

Supplemental Digital Content is available in the text

Background:

Opioid-use disorders (OUD) and hepatitis C or B co-infection (HEP) are common among people living with HIV (PLHIV). The impact of OUD on innate and adaptive immunity among PLHIV with and without HEP is unknown.

Objectives:

To investigate the impact of OUD on monocyte and T-cell phenotypes, cytokine responses to lipopolysaccharide (LPS) and phytohemagglutinin (PHA), and plasma inflammatory markers, among PLHIV with and without HEP.

Methods:

Cross-sectional study enrolling PLHIV receiving ART, with and without OUD. Flow cytometry determined monocyte and T-cell phenotypes; LPS and PHA-induced cytokine production was assessed following LPS and PHA stimulation by multiplex cytokine array; plasma IL-6, soluble CD163, and soluble CD14 were measured by ELISA.

Results:

Twenty-two PLHIV with OUD and 37 PLHIV without OUD were included. PLHIV with OUD exhibited higher frequencies of intermediate (CD14⁺⁺CD16⁺) and nonclassical (CD14^dimCD16⁺) monocytes when compared with PLHIV without OUD (P = 0.0025; P = 0.0001, respectively), regardless of HEP co-infection. Soluble CD163 and monocyte cell surface CD163 expression was increased among PLHIV with OUD and HEP, specifically. Regardless of HEP co-infection, PLHIV with OUD exhibited reduced production of IL-10, IL-8, IL-6, IL-1alpha, and TNF-alpha in response to LPS when compared with PLHIV without OUD; PHA-induced production of IL-10, IL-1alpha, IL-1beta, IL-6, and TNF-alpha were also reduced among individuals with OUD.

Conclusion:

OUD among PLHIV are associated with altered monocyte phenotypes and a dysregulated innate cytokine response. Defining underlying mechanisms of opioid-associated innate immune dysregulation among PLHIV should be prioritized to identify optimal OUD treatment strategies.

Reduction of Immune Activation and Partial Recovery of Staphylococcal Enterotoxin B-Induced Cytokine Production After Switching to an Integrase Strand Transfer Inhibitor-Containing Regimen: Results from an Observational Cohort Study

Background and Objective

Despite integrase strand transfer inhibitor (INSTI)-containing regimens now being considered a preferred option for both initial therapy and switching strategies in virologically suppressed patients, their effects on lymphocyte phenotypes and functions in the course of effective combination antiretroviral therapy (cART) are still unclear. Thus, we investigated the effect of a 24-week elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate (EVG/c/FTC/TDF) regimen on the T cell compartment and HIV reservoirs in HIV-infected patients switching from a suppressive protease inhibitor-based regimen.

Methods

Thirty HIV-positive patients receiving suppressive tenofovir disoproxil fumarate/emtricitabine (TDF + FTC) (for a median of 5 years) in association with either darunavir/ritonavir (DVR/r) (47%) or atazanavir/ritonavir (ATV/r) (53%) were followed up for 24 weeks after switching to EVG/c/FTC/TDF. At baseline (week 0 [W0]) and after 12 (W12) and 24 (W24) weeks we analyzed HLA-DR (human leukocyte antigen–DR isotype)/CD38/Ki67/CCR7 (C-C chemokine receptor type 7)/CD45RA/CD127/PD-1 (programmed cell death-1) on CD4/CD8, interferon (IFN)-γ/interleukin (IL)-2 after HIV/Staphylococcal enterotoxin B (SEB) exposure (flow cytometry); total, integrated, and unintegrated HIV-DNA; and residual low-level HIV viremia (quantitative polymerase chain reaction [qPCR]).

Results

While EVG/c/FTC/TDF introduction resulted in a stable CD4+ and CD8+ count, residual low-level HIV-RNA viremia, and HIV reservoirs, we observed a significant reduction in both activated CD4+ (p = 0.016) and CD8+ (p = 0.048) T cells, coupled with an increase in IL-2 and IFN-γ release by CD4+ and CD8+ effector memory T cells, and a decrease in cytokine production by terminally differentiated CD8+ T cells following SEB exposure. Furthermore, the magnitude of the reduction of activated HLA-DR + CD38 + CD8+ T cells (r = − 0.63, p = 0.014) inversely correlates with the amount of total HIV-DNA at W24.

Conclusions

Our data show a favorable effect of EVG/c/FTC/TDF switch to preserve immune activation-driven damage to T cell homeostasis, restore the multifunctional properties of effector T cells, and possibly contain cell-associated HIV viral burden in already virologically suppressed patients.

Foxp3+Helios+ regulatory T cells are associated with monocyte subsets and their PD-1 expression during acute HIV-1 infection

Background

Helios has been reported to stabilize regulatory T (Treg) suppressive function. Programmed cell death protein 1 (PD-1) expression in three human monocyte subsets modulates immune responses. Recently, our team reported that three monocyte subsets are associated with T helper cell differentiation in HIV-1-infected patients. Until now, the effects of monocyte subsets and their PD-1 expression on Foxp3⁺Helios⁺ Treg cells have not been fully characterized, especially during acute HIV-1 infection.

Results

The frequency of Foxp3⁺Helios⁺CD45RA⁺ Treg cells is significantly higher in patients with acute HIV-1 infection than those of healthy controls and chronic HIV-1-infected patients undergoing combined antiretroviral therapy. The frequency of Foxp3⁺Helios⁺CD45RA⁺ Treg cells is inversely correlated with CD4 T-cell counts and the CD4/CD8 ratio in chronic HIV-1-infected patients. During acute HIV-1 infection, the frequency of Foxp3⁺Helios⁺CD45RA⁺ Treg cells is inversely correlated with the frequency of the intermediate CD14⁺⁺CD16⁺ monocyte subset, but positively correlated with PD-1 expression in both intermediate CD14⁺⁺CD16⁺ and non-classical CD14⁺CD16⁺⁺ monocyte subsets.

Conclusions

In this study, the perturbations of Foxp3⁺Helios⁺ Treg cells were characterized, and the association between monocyte subsets and their PD-1 expression and Foxp3⁺Helios⁺ Treg cells was evaluated during HIV-1 infection. Our observations provide new evidence of the roles for Foxp3⁺Helios⁺ Treg cells and PD-1 expression on monocyte subsets in HIV pathogenesis.

Changes in Inflammation but Not in T-Cell Activation Precede Non-AIDS-Defining Events in a Case-Control Study of Patients on Long-term Antiretroviral Therapy

Background

We examined changes in soluble inflammatory cytokines and T-cell activation after antiretroviral therapy (ART) initiation in an AIDS Clinical Trials Group (ACTG) nested case-control study.

Methods

Cases were 143 human immunodeficiency virus (HIV)-infected adults who developed a non-AIDS event; 315 controls remained event-free. Specimens were tested pre-ART, year 1 post-ART, and at the visit preceding the event. Conditional logistic regression evaluated the associations of biomarker changes with non-AIDS events.

Results

Inflammatory and most activation biomarkers declined from pre-ART to year 1 for cases and controls. Subsequently, inflammatory biomarkers remained mostly stable in controls but not cases. Cellular activation markers generally declined for both cases and controls between year 1 and the pre-event sampling. Controls with greater pre-ART RNA levels or lower CD4+ levels had higher biomarker levels while also experiencing greater biomarker declines in the first year of ART. Changes in biomarkers to year 1 showed no significant associations with non-AIDS events. Cases, however, had significantly greater increases in all plasma biomarkers (but not cellular activation) from year 1 to the visit preceding the event.

Conclusions

Inflammation increases prior to non-AIDS events in treated HIV-infected adults. These biomarker changes may reflect subclinical disease processes or other alterations in the inflammatory environment that causally contribute to disease.

Clinical Trials Registration

NCT00001137.

Inflammatory and immunometabolic consequences of gut dysfunction in HIV: Parallels with IBD and implications for reservoir persistence and non-AIDS comorbidities

The gastrointestinal mucosa is critical for maintaining the integrity and functions of the gut. Disruption of this barrier is a hallmark and a risk factor for many intestinal and chronic inflammatory diseases. Inflammatory bowel disease (IBD) and HIV infection are characterized by microbial translocation and systemic inflammation. Despite the clinical overlaps between HIV and IBD, significant differences exist such as the severity of gut damage and mechanisms of immune cell homeostasis. Studies have supported the role of metabolic activation of immune cells in promoting chronic inflammation in HIV and IBD. This inflammatory response persists in HIV+ persons even after long-term virologic suppression by antiretroviral therapy (ART). Here, we review gut dysfunction and microbiota changes during HIV infection and IBD, and discuss how this may induce metabolic reprogramming of monocytes, macrophages and T cells to impact disease outcomes. Drawing from parallels with IBD, we highlight how factors such as lipopolysaccharides, residual viral replication, and extracellular vesicles activate biochemical pathways that regulate immunometabolic processes essential for HIV persistence and non-AIDS metabolic comorbidities. This review highlights new mechanisms and support for the use of immunometabolic-based therapeutics towards HIV remission/cure, and treatment of metabolic diseases.

In vitro Infection of Primary Human Monocytes with HIV-1

Monocyte infection by HIV-1 is an important component of chronic HIV pathogenesis. Following infection by HIV-1, monocytes are able to cross the blood brain barrier and set up a viral reservoir in the central nervous system. Additionally, in the setting of chronic HIV-1 infection, monocytes can become activated either directly through HIV-1 infection or indirectly via HIV-1-mediated systemic immune activation. Currently, there are few studies looking at HIV-1 infection of primary human monocytes in vitro. Furthermore, detection of successful HIV-1 infection of monocytes can be laborious requiring an ELISA for p24 or assessing levels of HIV-1 mRNA or DNA. This protocol utilizes an HIV-1 strain expressing GFP to allow for easy quantification of HIV-1 infection by fluorescence-assisted cell sorting (FACS). By determining HIV-1 infection by FACS one can take advantage of its multiparametric nature allowing for the use of less cells and the ability to assess the expression of other markers on HIV-1⁺ and HIV-1^- cells in the same experiment. Additionally, this protocol could be modified to study HIV-1 infection of other cells including CD4⁺ T cells.

The HIV Reservoir in Monocytes and Macrophages

In people living with HIV (PLWH) who are failing or unable to access combination antiretroviral therapy (cART), monocytes and macrophages are important drivers of pathogenesis and progression to AIDS. The relevance of the monocyte/macrophage reservoir in PLWH receiving cART is debatable as in vivo evidence for infected cells is limited and suggests the reservoir is small. Macrophages were assumed to have a moderate life span and lack self-renewing potential, but recent discoveries challenge this dogma and suggest a potentially important role of these cells as long-lived HIV reservoirs. This, combined with new HIV infection animal models, has led to a resurgence of interest in monocyte/macrophage reservoirs. Infection of non-human primates with myeloid-tropic SIV implicates monocyte/macrophage activation and infection in the brain with neurocognitive disorders, and infection of myeloid-only humanized mouse models are consistent with the potential of the monocyte/macrophage reservoir to sustain infection and be a source of rebound viremia following cART cessation. An increased resistance to HIV-induced cytopathic effects and a reduced susceptibility to some antiretroviral drugs implies macrophages may be relevant to residual replication under cART and to rebound viremia. With a reappraisal of monocyte circulation dynamics, and the development of techniques to differentiate between self-renewing tissue-resident, and monocyte-derived macrophages in different tissues, a new framework exists to contextualize and evaluate the significance and relevance of the monocyte/macrophage HIV reservoir. In this review, we discuss recent developments in monocyte and macrophage biology and appraise current and emerging techniques to quantify the reservoir. We discuss how this knowledge influences our evaluation of the myeloid HIV reservoir, the implications for HIV pathogenesis in both viremic and virologically-suppressed PLWH and the need to address the myeloid reservoir in future treatment and cure strategies.

Clinical and neuroimaging correlates of cognition in HIV

This study investigated whether HIV-positive participants, stable on combined antiretroviral therapy (cART), showed cognitive impairments relative to HIV-negative controls; and whether clinical and neuroimaging factors correlated with cognitive function in the HIV-positive participants. One hundred and twenty-six white men who have sex with men, of whom 78 were HIV-positive and stable on cART and 48 were HIV negative, were recruited to this cross-sectional study. The median age of HIV-positive participants in this study was 47. They underwent clinical and neuropsychological evaluation and magnetic resonance imaging of the brain, including diffusion tensor imaging (DTI). Cognitive scores for both groups were compared, and regression models were run to explore the influence of clinical, psychiatric, lifestyle, and neuroimaging variables on cognition. The prevalence of neurocognitive impairment, using the multivariate normative comparison criteria, was 28% in HIV-positive participants and 5% in HIV-negative participants. After covarying for age, years of education, and non-English speaking background, there were significant differences between the HIV group and the controls across four cognitive domains. The HIV group showed significantly higher mean diffusivity (MD) and lower fractional anisotropy (FA) than the control group on DTI. Although anxiety levels were clinically low, anxiety and DTI measures were the only variables to show significant correlations with cognitive function. In the HIV group, poorer cognitive performance was associated with higher MD and lower FA on DTI and higher (albeit clinically mild) levels of anxiety. Our findings suggest that white matter changes and subtle anxiety levels contribute independently to cognitive impairment in HIV.

Patho-immune Mechanisms of Hypertension in HIV: a Systematic and Thematic Review

PURPOSE OF REVIEW

To systematically review recent findings on the role of immune cell activation in the pathogenesis of hypertension in people living with HIV (PLWH) and compare studies from Sub-Saharan Africa with what is reported in the USA and European literature according to guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

RECENT FINDINGS

PLWH have an increased risk for development of hypertension and cardiovascular disease. Chronic immune activation contributes to hypertension but the inflammatory milieu that predisposes PLWH to hypertension is poorly understood. We identified 45 relevant studies from 13 unique African countries. The prevalence of hypertension in PLWH on antiretroviral therapy (ART) and the ART-naive PLWH ranged from 6 to 50% and 2 to 41%, respectively. Interleukin (IL)-17A, interferon (IFN)-γ, and higher CD4+ T cell counts were associated with hypertension in ART-treated participants. Targeting adaptive immune activation could provide improved care for hypertensive PLWH. Further research is needed to characterize the inflammatory milieu contributing to hypertension in PLWH especially in African populations where the global burden of HIV is the highest.

Inflammation Strikes Again: Frailty and HIV

PURPOSE OF REVIEW

As a consequence of antiretroviral therapy, the proportion of older HIV-infected adults is increasing, with a concomitant shift in burden of illness to age-related syndromes and disease. Frailty is an age-related syndrome of increased vulnerability to stress, predictive of major adverse clinical outcomes among HIV-infected and uninfected persons alike. Understanding frailty pathogenesis is critical to developing interventions to improve health outcomes in HIV. Here, we review the current evidence for the relationship between inflammation and frailty in HIV, and the potential for novel, inflammation-targeted interventions.

RECENT FINDINGS

Dysregulated inflammation has been consistently associated with frailty in elderly HIV-uninfected persons. Dysregulated inflammation is also central to HIV pathophysiology and several recent studies have demonstrated the important association of inflammation with frailty in HIV. Some evidence suggests that anti-inflammatory therapies may be effective in ameliorating the adverse impact of frailty among aging HIV-infected adults, though further investigation is necessary. Inflammation has been implicated in frailty in HIV infection, and improved understanding of the role that inflammation plays in frailty pathogenesis is key to the development of effective therapies to slow or prevent frailty in the vulnerable HIV-infected population.

Atrial fibrillation and human immunodeficiency virus type-1 infection: a systematic review. Implications for anticoagulant and antiarrhythmic therapy

The prevalence and incidence of atrial fibrillation/flutter (AF/AFL) in patients with human immunodeficiency virus type-1 (HIV-1) infection have been poorly investigated. We performed a systematic review using PubMed and Cochrane Database of Systematic Reviews, and screening of references, searching for clinical studies reporting on the association between HIV-1 infection and AF/AFL. We also summarized the main interactions of antiretroviral agents with antithrombotic and antiarrhythmic drugs. We found a prevalence of AF/AFL ranging from 2.0% to 5.13% in patients with HIV-1, with an incidence rate of 3.6/1000 person-years. Low CD4+ count (<200-250 cells ml^-1 ) and high viral load were predictors of AF/AFL. Regarding drugs interactions, nucleoside reverse transcriptase inhibitors, integrase inhibitor and maraviroc have the lowest interactions with oral anticoagulants. Among anticoagulants, dabigatran presents the most favourable profile. Most of antiarrhythmic drugs interact with protease inhibitors, with beta blockers and diltiazem having fewer interactions. The few studies available suggest a non-negligible prevalence of AF/AFL in patients with HIV-1 infection. Awareness of potential interactions with anticoagulation and antiarrhythmic drugs is needed to offer optimal management in this population.

HIV and Cardiovascular Disease: Role of Immunometabolic Perturbations

The successful rollout of anti-retroviral therapy ensured that HIV is increasingly managed as a chronic condition. HIV-positive persons are therefore exhibiting increased cardiovascular complications. This review focuses on the emerging role of "immunometabolism" within the context of HIV-related immune dysregulation and cardiovascular disease onset. Here, persistent immune activation contributes to pathophysiological perturbations during early infection, resulting in immune cell metabolic reprogramming and the activation of coagulation pathways in HIV-positive individuals.