The cytokine network of acute HIV infection: a promising target for vaccines and therapy to reduce viral set-point?

Human induced pluripotent stem cell-derived cardiomyocytes to study inflammation-induced aberrant calcium transient

Heart failure with preserved ejection fraction (HFpEF) is commonly found in persons living with HIV (PLWH) even when antiretroviral therapy suppresses HIV viremia. However, studying this condition has been challenging because an appropriate animal model is not available. In this article, we studied calcium transient in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in culture to simulate the cardiomyocyte relaxation defect noted in PLWH and HFpEF and assess whether various drugs have an effect. We show that treatment of hiPSC-CMs with inflammatory cytokines (such as interferon-γ or TNF-α) impairs their Ca2+ uptake into sarcoplasmic reticulum and that SGLT2 inhibitors, clinically proven as effective for HFpEF, reverse this effect. Additionally, treatment with mitochondrial antioxidants (like mito-Tempo) and certain antiretrovirals resulted in the reversal of the effects of these cytokines on calcium transient. Finally, incubation of hiPSC-CMs with serum from HIV patients with and without diastolic dysfunction did not alter their Ca2+-decay time, indicating that the exposure to the serum of these patients is not sufficient to induce the decrease in Ca2+ uptake in vitro. Together, our results indicate that hiPSC-CMs can be used as a model to study molecular mechanisms of inflammation-mediated abnormal cardiomyocyte relaxation and screen for potential new interventions.

Engineered dendritic cells-derived exosomes harboring HIV-1 Nefmut-Tat fusion protein and heat shock protein 70: A promising HIV-1 safe vaccine candidate

Antigen presenting cells (APCs)-derived exosomes are nano-vesicles that can induce antigen-specific T cell responses, and possess therapeutic effects in clinical settings. Moreover, dendritic cells (DCs)-based vaccines have been developed to combat human immunodeficiency virus-1 (HIV-1) infection in preclinical and clinical trials. We investigated the immunostimulatory effects (B- and T-cells activities) of DCs- and exosomes-based vaccine constructs harboring HIV-1 Nefmut-Tat fusion protein as an antigen candidate and heat shock protein 70 (Hsp70) as an adjuvant in mice. The modified DCs and engineered exosomes harboring Nefmut-Tat protein or Hsp70 were prepared using lentiviral vectors compared to electroporation, characterized and evaluated by in vitro and in vivo immunological tests. Our data indicated that the engineered exosomes induced high levels of total IgG, IgG2a, IFN-γ, TNF-α and Granzyme B. Moreover, co-injection of exosomes harboring Hsp70 could significantly increase the secretion of antibodies, cytokines and Granzyme B. The highest levels of IFN-γ and TNF-α were observed in exosomes harboring Nefmut-Tat combined with exosomes harboring Hsp70 (Exo-Nefmut-Tat + Exo-Hsp70) regimen after single-cycle replicable (SCR) HIV-1 exposure. Generally, Exo-Nefmut-Tat + Exo-Hsp70 regimen can be considered as a promising safe vaccine candidate due to high T-cells (Th1 and CTL) activity and its maintenance against SCR HIV-1 exposure.

Decreased IL-1 β Secretion as a Potential Predictor of Tuberculosis Recurrence in Individuals Diagnosed with HIV

Background: The mechanisms of the formation of immunological competence against tuberculosis (TB), and especially those associated with HIV co-infection, remain poorly understood. However, there is an urgent need for risk recurrence predictive biomarkers, as well as for predictors of successful treatment outcomes. The goal of the study was to identify possible immunological markers of TB recurrence in individuals with HIV/TB co-infection. Methods: The plasma levels of IFN-γ, TNF-α, IL-10, and IL-1β (cytokines which play important roles in the immune activation and protection against Mycobacterium tuberculosis) were measured using ELISA EIA-BEST kits. The cytokine concentrations were determined using a standard curve obtained with the standards provided by the manufacturer of each kit. Results: A total of 211 individuals were enrolled in the study as follows: 62 patients with HIV/TB co-infection, 52 with HIV monoinfection, 52 with TB monoinfection, and 45 healthy donors. Out of the 62 patients with HIV/TB, 75.8% (47) of patients were newly diagnosed with HIV and TB, and 24.2% (15) displayed recurrent TB and were newly diagnosed with HIV. Decreased levels of IFN-γ, TNF-α, and IL-10 were observed in patients with HIV/TB when compared with HIV and TB patients. However, there was no difference in IFN-γ, TNF-α, or IL-10 secretion between both HIV/TB groups. At the same time, an almost 4-fold decrease in Il-1β levels was detected in the HIV/TB group with TB recurrence when compared with the HIV/TB group (p = 0.0001); a 2.8-fold decrease when compared with HIV patients (p = 0.001); and a 2.2-fold decrease with newly diagnosed TB patients (p = 0.001). Conclusions: Significantly decreased Il-1β levels in HIV/TB patients' cohort with secondary TB indicate that this cytokine can be a potential biomarker of TB recurrence.

Inflammatory profile of vertically HIV-1 infected adolescents receiving ART in Cameroon: a contribution toward optimal pediatric HIV control strategies

Antiretroviral therapy (ART) has improved the lifespan of people living with HIV. However, their immune system remains in a state of sustained activation/inflammation, which favors viral replication and depletion of helper T-cells with varying profiles according to ART-response. We herein sought to ascertain the inflammatory profile of adolescents living with perinatal HIV-1 infection (ALPHI) receiving ART in an African context. In this cross-sectional and comparative study among ART-experienced ALPHI in Yaoundé-Cameroon, HIV-1 RNA was measured by Abbott Real-time PCR; CD4 cells were enumerated using flow cytometry; serum cytokines were measured by ELISA; HIV-1 proviral DNA was genotyped by Sanger-sequencing; and archived drug resistance mutations (ADRMs) were interpreted using Stanford HIVdb.v9.0.1. Overall, 73 adolescents were enrolled (60 ALPHI and 13 HIV-1 negative peers) aged 15 (13-18) years; 60.00% were female. ART median duration was 92 (46-123) months; median viral load was 3.99 (3.17-4.66) RNA Log10 (copies)/mL and median CD4 count was 326 (201-654) cells/mm3. As compared to HIV-negative adolescents, TNFα was highly expressed among ALPHI (p<0.01). Following a virological response, inflammatory cytokines (IFNγ and IL-12), anti-inflammatory cytokines (IL-4 and IL-10) and inflammation-related cytokines (IL-6 and IL-1β) were highly expressed with viral suppression (VS) vs. virological failure (VF), while the chemokine CCL3 was highly expressed with VF (p<0.01). Regarding the immune response, the inflammatory cytokine TNFα was highly expressed in those that are immunocompetent (CD4≥500 cell/mm3) vs. immunocompromised (CD4<500 cell/mm3), p ≤ 0.01; while chemokine CCL2 was highly expressed in the immunocompromised (p<0.05). In the presence of ADRMs, IL-4 and CCL3 were highly expressed (p=0.027 and p=0.043 respectively). Among ART-experienced ALPHI in Cameroon, the TNFα cytokine was found to be an inflammatory marker of HIV infection; IFNγ, IL-1β, IL-6, and IL-12 are potential immunological markers of VS and targeting these cytokines in addition to antiretroviral drugs may improve management. Moreover, CCL3 and CCL2 are possible predictors of VF and/or being immunocompromised and could serve as surrogates of poor ART response.

Divergent Cytokine and Chemokine Responses at Early Acute Simian Immunodeficiency Virus Infection Correlated with Virus Replication and CD4 T Cell Loss in a Rhesus Macaque Model

Cytokine and chemokine levels remain one of the significant predictive factors of HIV pathogenesis and disease outcome. Understanding the impact of cytokines and chemokines during early acute infection will help to recognize critical changes during HIV pathogenesis and might assist in establishing improved HIV treatment and prevention methods. Sixty-one cytokines and chemokines were evaluated in the plasma of an SIV-infected rhesus macaque model. A substantial change in 11 cytokines/growth factors and 9 chemokines were observed during acute infection. Almost all the cytokines/chemokines were below the baseline values for an initial couple of days of infection. We detected six important cytokines/chemokines, such as IL-18, IP-10, FLT3L, MCP-1, MCP-2, and MIP-3β, that can be used as biomarkers to predict the peripheral CD4+ T cell loss and increased viral replication during the acute SIV/HIV infection. Hence, regulating IL-18, IP-10, FLT3L, MCP-1, MCP-2, and MIP-3β expression might provide an antiviral response to combat acute SIV/HIV infection.

HIV but Not CMV Replication Alters the Blood Cytokine Network during Early HIV Infection in Men

OBJECTIVE

CMV coinfection contributes to sustained immune activation in people with chronic HIV. In particular, asymptomatic CMV shedding in semen has been associated with increased local and systemic immune activation, even during suppressive antiretroviral therapy (ART). However, the effect of seminal CMV shedding in people with HIV in the earliest phase of HIV infection is not known.

METHODS

Using Luminex, we measured the concentration of 34 cytokines in the blood plasma of sixty-nine men who had sex with men with or without HIV and in subgroups of CMV shedders vs. non-shedders. Differences in blood plasma cytokines between groups were investigated using the multivariate supervised partial least squares discriminant analysis method.

RESULTS

Independently of CMV, we found that concentrations of IP-10, MIG, MCP-1, I-TAC 10, IL-16, and MIP-1β were modulated in the earliest phase of HIV infection compared with control individuals without HIV. In people with HIV, there was no difference in blood cytokines among CMV shedders vs. non-shedders.

CONCLUSION

In early/acute HIV infection, asymptomatic CMV shedding in semen does not drive additional cytokine changes in blood. Early ART initiation should remain the priority, while the added benefit of CMV suppression during the various stages of HIV infection needs to be further investigated.

Infection with HIV-1 subtype D among acutely infected Ugandans is associated with higher median concentration of cytokines compared to subtype A

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HIV-1 subtype D exhibited significantly higher median concentrations of cytokines

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IL-12/23p40 and IL-1α were associated with faster CD4⁺T cell count decline

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bFGF was associated with maintenance of CD4+ counts above 350 cells/microliter

Objective

The observation that HIV-1 subtype D progresses faster to disease than subtype A prompted us to examine cytokine levels early after infection within the predominant viral subtypes that circulate in Uganda and address the following research questions: (1) Do cytokine levels vary between subtypes A1 and D? (2) Do cytokine profiles correlate with disease outcomes?

Methods

To address these questions, HIV-1 subtypes were determined by population sequencing of the HIV-1 pol gene and 37 plasma cytokine concentrations were evaluated using V-Plex kits on Meso Scale Discovery platform in 65 recent sero-converters.

Results

HIV-1 subtype D (pol) infections exhibited significantly higher median plasma concentrations of IL-5, IL-16, IL-1α, IL-7, IL-17A, CCL11 (Eotaxin-1), CXCL10 (IP-10), CCL13 (MCP-4) and VEGF-D compared to subtype A1 (pol) infections. We also found that IL-12/23p40 and IL-1α were associated with faster CD4⁺T cell count decline, while bFGF was associated with maintenance of CD4+ counts above 350 cells/microliter.

Conclusion

Our results suggest that increased production of cytokines in early HIV infection may trigger a disruption of the immune environment and contribute to pathogenic mechanisms underlying the accelerated disease progression seen in individuals infected with HIV-1 subtype D in Uganda.

Effect of HIV suppression on the cytokine network in blood and seminal plasma

OBJECTIVE

HIV infection disrupts the cytokine network and this disruption is not completely reversed by antiretroviral therapy (ART). Characterization of cytokine changes in blood and genital secretions is important for understanding HIV pathogenesis and the mechanisms of HIV sexual transmission. Here, we characterized the cytokine network in individuals longitudinally sampled before they began ART and after achieving suppression of HIV RNA.

METHODS

We measured concentrations of 34 cytokine/chemokines using multiplex bead-based assay in blood and seminal plasma of 19 men with HIV-1 prior to and after viral suppression. We used Partial Least Squares Discriminant Analysis (PLS-DA) to visualize the difference in cytokine pattern between the time points. Any cytokines with VIP scores exceeding 1 were deemed important in predicting suppression status and were subsequently tested using Wilcoxon Signed Rank Tests.

RESULTS

PLS-DA projections in blood were fairly similar before and after viral suppression. In contrast, the difference in PLS-DA projection observed in semen emphasizes that the immunological landscape and immunological needs are very different before and after ART in the male genital compartment. When tested individually, four cytokines were significantly different across time points in semen (MIG, IL-15, IL-7, I-TAC), and two in blood (MIG and IP-10).

CONCLUSION

Viral suppression with ART impacts the inflammatory milieu in seminal plasma. In contrast, the overall effect on the network of cytokines in blood was modest but consistent with prior analyses. These results identify specific changes in the cytokine networks in semen and blood as the immune system acclimates to chronic, suppressed HIV infection.

HIV-1 Vif suppresses antiviral immunity by targeting STING

HIV-1 infection-induced cGAS-STING-TBK1-IRF3 signaling activates innate immunity to produce type I interferon (IFN). The HIV-1 nonstructural protein viral infectivity factor (Vif) is essential in HIV-1 replication, as it degrades the host restriction factor APOBEC3G. However, whether and how it regulates the host immune response remains to be determined. In this study, we found that Vif inhibited the production of type I IFN to promote immune evasion. HIV-1 infection induced the activation of the host tyrosine kinase FRK, which subsequently phosphorylated the immunoreceptor tyrosine-based inhibitory motif (ITIM) of Vif and enhanced the interaction between Vif and the cellular tyrosine phosphatase SHP-1 to inhibit type I IFN. Mechanistically, the association of Vif with SHP-1 facilitated SHP-1 recruitment to STING and inhibited the K63-linked ubiquitination of STING at Lys337 by dephosphorylating STING at Tyr162. However, the FRK inhibitor D-65495 counteracted the phosphorylation of Vif to block the immune evasion of HIV-1 and antagonize infection. These findings reveal a previously unknown mechanism through which HIV-1 evades antiviral immunity via the ITIM-containing protein to inhibit the posttranslational modification of STING. These results provide a molecular basis for the development of new therapeutic strategies to treat HIV-1 infection.

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.

Evolution and Diversity of Immune Responses during Acute HIV Infection

Understanding the earliest immune responses following HIV infection is critical to inform future vaccines and therapeutics. Here, we review recent prospective human studies in at-risk populations that have provided insight into immune responses during acute infection, including additional relevant data from non-human primate (NHP) studies. We discuss the timing, nature, and function of the diverse immune responses induced, the onset of immune dysfunction, and the effects of early anti-retroviral therapy administration. Treatment at onset of viremia mitigates peripheral T and B cell dysfunction, limits seroconversion, and enhances cellular antiviral immunity despite persistence of infection in lymphoid tissues. We highlight pertinent areas for future investigation, and how application of high-throughput technologies, alongside targeted NHP studies, may elucidate immune response features to target in novel preventions and cures.

Virulent African horse sickness virus serotype 4 interferes with the innate immune response in horse peripheral blood mononuclear cells in vitro

African horse sickness (AHS) is caused by African horse sickness virus (AHSV), a double stranded RNA (dsRNA) virus of the genus Orbivirus, family Reoviridae. For the development of new generation AHS vaccines or antiviral treatments, it is crucial to understand the host immune response against the virus and the immune evasion strategies the virus employs. To achieve this, the current study used transcriptome analysis of RNA sequences to characterize and compare the innate immune responses activated during the attenuated AHSV serotype 4 (attAHSV4) (in vivo) and the virulent AHSV4 (virAHSV4) (in vitro) primary and secondary immune responses in horse peripheral blood mononuclear cells (PBMC) after 24 h. The pro-inflammatory cytokine and chemokine responses were negatively regulated by anti-inflammatory cytokines, whereas the parallel type I and type III IFN responses were maintained downstream of nucleic acid sensing pattern recognition receptor (PRR) signalling pathways during the attAHSV4 primary and secondary immune responses. It appeared that after translation, virAHSV4 proteins were able to interfere with the C-terminal IRF association domain (IAD)-type 1 (IAD1) containing IRFs, which inhibited the expression of type I and type III IFNs downstream of PRR signalling during the virAHSV4 primary and secondary immune responses. Viral interference resulted in an impaired innate immune response that was not able to eliminate virAHSV4-infected PBMC and gave rise to prolonged expression of pro-inflammatory cytokines and chemokines during the virAHSV4 induced primary immune response. Indicating that virAHSV4 interference with the innate immune response may give rise to an excessive inflammatory response that causes immunopathology, which could be a major contributing factor to the pathogenesis of AHS in a naïve horse. Viral interference was overcome by the fast kinetics and increased effector responses of innate immune cells due to trained innate immunity and memory T cells and B cells during the virAHSV4 secondary immune response.

Dysregulation of IL-17/IL-22 Effector Functions in Blood and Gut Mucosal Gamma Delta T Cells Correlates With Increase in Circulating Leaky Gut and Inflammatory Markers During cART-Treated Chronic SIV Infection in Macaques

HIV-associated inflammation has been implicated in the premature aging and increased risk of age-associated comorbidities in cART-treated individuals. However, the immune mechanisms underlying the chronic inflammatory state of cART-suppressed HIV infection remain unclear. Here, we investigated the role of γδT cells, a group of innate IL-17 producing T lymphocytes, in the development of systemic inflammation and leaky gut phenotype during cART-suppressed SIV infection of macaques. Plasma levels of inflammatory mediators, intestinal epithelial barrier disruption (IEBD) and microbial translocation (MT) biomarkers, and Th1/Th17-type cytokine functions were longitudinally assessed in blood and gut mucosa of SIV-infected, cART-suppressed macaques. Among the various gut mucosal IL-17/IL-22-producing T lymphocyte subsets including Th17, γδT, CD161+ CD8+ T, and MAIT cells, a specific decline in the Vδ2 subset of γδT cells and impaired IL-17/IL-22 production in γδT cells significantly correlated with the subsequent increase in plasma IEBD/MT markers (IFABP, LPS-binding protein, and sCD14) and pro-inflammatory cytokines (IL-6, IL-1β, IP10, etc.) despite continued viral suppression during long-term cART. Further, the plasma inflammatory cytokine signature during long-term cART was distinct from acute SIV infection and resembled the inflammatory cytokine profile of uninfected aging (inflammaging) macaques. Overall, our data suggest that during cART-suppressed chronic SIV infection, dysregulation of IL-17/IL-22 cytokine effector functions and decline of Vδ2 γδT cell subsets may contribute to gut epithelial barrier disruption and development of a distinct plasma inflammatory signature characteristic of inflammaging. Our results advance the current understanding of the impact of chronic HIV/SIV infection on γδT cell functions and demonstrate that in the setting of long-term cART, the loss of epithelial barrier-protective functions of Vδ2 T cells and ensuing IEBD/MT occurs before the hallmark expansion of Vδ1 subsets and skewed Vδ2/Vδ1 ratio. Thus, our work suggests that novel therapeutic approaches toward restoring IL-17/IL-22 cytokine functions of intestinal Vδ2 T cells may be beneficial in preserving gut epithelial barrier function and reducing chronic inflammation in HIV-infected individuals.

Cytokine Network and Sexual Human Immunodeficiency Virus Transmission in Men Who Have Sex With Men

BACKGROUND

Seminal human immunodeficiency virus (HIV) transmission from men to their partners remains the main driver of HIV epidemics worldwide. Semen is not merely a carrier of the virus, but also provides an immunological milieu that affects HIV transmission.

METHODS

We collected blood and semen from people with HIV whose epidemiologically linked sexual partners either did or did not acquire HIV. Viral transmission was confirmed by phylogenetic linkage (HIV pol). We measured the concentration of 34 cytokines/chemokines by Luminex in the blood and semen of 21 source partners who transmitted HIV (transmitters) and 22 who did not transmit HIV (nontransmitters) to their sexual partners. Differences between cytokine profiles in transmitters versus nontransmitters were analyzed using the multivariate statistical technique of partial least square discriminant analysis.

RESULTS

The cytokine profile in seminal fluid, but not in peripheral blood, was significantly different between men who have sex with men (MSM) who transmitted HIV and those who did not transmit HIV to their sexual partners (E = 19.77; P < .01). This difference persisted after excluding people with undetectable HIV RNA levels in nontransmitters.

CONCLUSIONS

Seminal cytokine profiles correlated with transmission or nontransmission of HIV from the infected MSM to their partners, independently from seminal viral load. Seminal cytokine spectra might be a contributing determinant of sexual HIV transmission, thus providing new directions for the development of strategies aimed at preventing HIV transmission.

Ex vivo rectal explant model reveals potential opposing roles of Natural Killer cells and Marginal Zone-like B cells in HIV-1 infection

Our understanding of innate immune responses in human rectal mucosal tissues (RM) and their contributions to promoting or restricting HIV transmission is limited. We defined the RM composition of innate and innate-like cell subsets, including plasmacytoid dendritic cells; CD1c + myeloid DCs; neutrophils; macrophages; natural killer cells (NK); Marginal Zone-like B cells (MZB); γδ T cells; and mucosal-associated invariant T cells in RM from 69 HIV-negative men by flow cytometry. Associations between these cell subsets and HIV-1 replication in ex vivo RM explant challenge experiments revealed an inverse correlation between RM-NK and p24 production, in contrast to a positive association between RM-MZB and HIV replication. Comparison of RM and blood-derived MZB and NK illustrated qualitative and quantitative differences between tissue compartments. Additionally, 22 soluble molecules were measured in a subset of explant cultures (n = 26). Higher production of IL-17A, IFN-γ, IL-10, IP-10, GM-CSF, sFasL, Granzyme A, Granzyme B, Granulysin, and Perforin following infection positively correlated with HIV replication. These data show novel associations between MZB and NK cells and p24 production in RM and underscore the importance of inflammatory cytokines in mucosal HIV infection, demonstrating the likely critical role these innate immune responses play in early mucosal HIV replication in humans.

Persistent Immune Activation in HIV-1-Infected Ex Vivo Model Tissues Subjected to Antiretroviral Therapy: Soluble and Extracellular Vesicle-Associated Cytokines

BACKGROUND

Residual immune activation after successful antiretroviral therapy (ART) in HIV-1-infected patients is associated with the increased risk of complications. Cytokines, both soluble and extracellular vesicle (EV)-associated, may play an important role in this immune activation.

SETTING

Ex vivo tissues were infected with X4LAI04 or R5SF162 HIV-1. Virus replicated for 16 days, or tissues were treated with the anti-retroviral drug ritonavir.

METHODS

Viral replication and production of 33 cytokines in soluble and EV-associated forms were measured with multiplexed bead-based assays.

RESULTS

Both variants of HIV-1 efficiently replicated in tissues and triggered upregulation of soluble cytokines, including IL-1β, IL-7, IL-18, IFN-γ, MIP-1α, MIP-1β, and RANTES. A similar pattern was observed in EV-associated cytokine release by HIV-infected tissues. In addition, TNF-α and RANTES demonstrated a significant shift to a more soluble form compared with EV-associated cytokines. Ritonavir treatment efficiently suppressed viral replication; however, both soluble and EV-associated cytokines remained largely upregulated after 13 days of treatment. EV-associated cytokines were more likely to remain elevated after ART. Treatment of uninfected tissues with ritonavir itself did not affect cytokine release.

CONCLUSIONS

We demonstrated that HIV-1 infection of ex vivo lymphoid tissues resulted in their immune activation as evaluated by upregulation of various cytokines, both soluble and EV-associated. This upregulation persisted despite inhibition of viral replication by ART. Thus, similar to in vivo, HIV-1-infected human tissues ex vivo continue to be immune-activated after viral suppression, providing a new laboratory model to study this phenomenon.

Differential packaging of inflammatory cytokines/ chemokines and oxidative stress modulators in U937 and U1 macrophages-derived extracellular vesicles upon exposure to tobacco constituents

Smoking, which is highly prevalent in HIV-infected populations, has been shown to exacerbate HIV replication, in part via the cytochrome P450 (CYP)-induced oxidative stress pathway. Recently, we have shown that extracellular vesicles (EVs), derived from tobacco- and/or HIV-exposed macrophages, alter HIV replication in macrophages by cell-cell interactions. We hypothesize that cigarette smoke condensate (CSC) and/or HIV-exposed macrophage-derived EVs carry relatively high levels of pro-oxidant and pro-inflammatory cargos and/or low levels of antioxidant and anti-inflammatory cargos, which are key mediators for HIV pathogenesis. Therefore, in this study, we investigated differential packaging of pro- and anti-inflammatory cytokines/chemokines and pro- and anti-oxidant contents in EVs after CSC exposure to myeloid cells (uninfected U937 and HIV-infected U1 cells). Our results showed that relatively long to short exposures with CSC increased the expression of cytokines in EVs isolated from HIV-infected U1 macrophages. Importantly, pro-inflammatory cytokines, especially IL-6, were highly packaged in EVs isolated from HIV-infected U1 macrophages upon both long and short-term CSC exposures. In general, anti-inflammatory cytokines, particularly IL-10, had a lower packaging in EVs, while packaging of chemokines was mostly increased in EVs upon CSC exposure in both HIV-infected U1 and uninfected U937 macrophages. Moreover, we observed higher expression of CYPs (1A1 and 1B1) and lower expression of antioxidant enzymes (SOD-1 and catalase) in EVs from HIV-infected U1 macrophages than in uninfected U937 macrophages. Together, they are expected to increase oxidative stress factors in EVs derived from HIV-infected U1 cells. Taken together, our results suggest packaging of increased level of oxidative stress and inflammatory elements in the EVs upon exposure to tobacco constituents and/or HIV to myeloid cells, which would ultimately enhance HIV replication in macrophages via cell-cell interactions.

MAIT cells are functionally impaired in a Mauritian cynomolgus macaque model of SIV and Mtb co-infection

Mucosal-associated invariant T (MAIT) cells can recognize and respond to some bacterially infected cells. Several in vitro and in vivo models of Mycobacterium tuberculosis (Mtb) infection suggest that MAIT cells can contribute to control of Mtb, but these studies are often cross-sectional and use peripheral blood cells. Whether MAIT cells are recruited to Mtb-affected granulomas and lymph nodes (LNs) during early Mtb infection and what purpose they might serve there is less well understood. Furthermore, whether HIV/SIV infection impairs MAIT cell frequency or function at the sites of Mtb replication has not been determined. Using Mauritian cynomolgus macaques (MCM), we phenotyped MAIT cells in the peripheral blood and bronchoalveolar lavage (BAL) before and during infection with SIVmac239. To test the hypothesis that SIV co-infection impairs MAIT cell frequency and function within granulomas, SIV+ and -naïve MCM were infected with a low dose of Mtb Erdman, and necropsied at 6 weeks post Mtb-challenge. MAIT cell frequency and function were examined within the peripheral blood, BAL, and Mtb-affected lymph nodes (LN) and granulomas. MAIT cells did not express markers indicative of T cell activation in response to Mtb in vivo within granulomas in animals infected with Mtb alone. SIV and Mtb co-infection led to increased expression of the activation/exhaustion markers PD-1 and TIGIT, and decreased ability to secrete TNFα when compared to SIV-naïve MCM. Our study provides evidence that SIV infection does not prohibit the recruitment of MAIT cells to sites of Mtb infection, but does functionally impair those MAIT cells. Their impaired function could have impacts, either direct or indirect, on the long-term containment of TB disease.

Association between the cytokine storm, immune cell dynamics, and viral replicative capacity in hyperacute HIV infection

INTRODUCTION

Immunological damage in acute HIV infection (AHI) may predispose to detrimental clinical sequela. However, studies on the earliest HIV-induced immunological changes are limited, particularly in sub-Saharan Africa. We assessed the plasma cytokines kinetics, and their associations with virological and immunological parameters, in a well-characterized AHI cohort where participants were diagnosed before peak viremia.

METHODS

Blood cytokine levels were measured using Luminex and ELISA assays pre-infection, during the hyperacute infection phase (before or at peak viremia, 1-11 days after the first detection of viremia), after peak viremia (24-32 days), and during the early chronic phase (77-263 days). Gag-protease-driven replicative capacities of the transmitted/founder viruses were determined using a green fluorescent reporter T cell assay. Complete blood counts were determined before and immediately following AHI detection before ART initiation.

RESULTS

Untreated AHI was associated with a cytokine storm of 12 out of the 33 cytokines analyzed. Initiation of ART during Fiebig stages I-II abrogated the cytokine storm. In untreated AHI, virus replicative capacity correlated positively with IP-10 (rho = 0.84, P < 0.001) and IFN-alpha (rho = 0.59, P = 0.045) and inversely with nadir CD4⁺ T cell counts (rho = - 0.58, P = 0.048). Hyperacute HIV infection before the initiation of ART was associated with a transient increase in monocytes (P < 0.001), decreased lymphocytes (P = 0.011) and eosinophils (P = 0.003) at Fiebig stages I-II, and decreased eosinophils (P < 0.001) and basophils (P = 0.007) at Fiebig stages III-V. Levels of CXCL13 during the untreated hyperacute phase correlated inversely with blood eosinophils (rho = - 0.89, P < 0.001), basophils (rho = - 0.87, P = 0.001) and lymphocytes (rho = - 0.81, P = 0.005), suggesting their trafficking into tissues. In early treated individuals, time to viral load suppression correlated positively with plasma CXCL13 at the early chronic phase (rho = 0.83, P = 0.042).

CONCLUSION

While commencement of ART during Fiebig stages I-II of AHI abrogated the HIV-induced cytokine storm, significant depletions of eosinophils, basophils, and lymphocytes, as well as transient expansions of monocytes, were still observed in these individuals in the hyperacute phase before the initiation of ART, suggesting that even ART initiated during the onset of viremia does not abrogate all HIV-induced immune changes.

Different pattern of stool and plasma gastrointestinal damage biomarkers during primary and chronic HIV infection

Introduction

Primary HIV infection (PHI) is the initial phase after HIV acquisition characterized by high viral replication, massive inflammatory response and irreversible immune-damage, particularly at the gastrointestinal level. In this study we aimed to characterize the dynamics of gastrointestinal damage biomarkers during the different phases of HIV infection and assess their association with HIV-disease markers and their accuracy to differentiate PHI from chronic HIV infection (CHI).

Methods

PHI-individuals (n = 57) were identified as HIV-seronegative/HIV-RNA positive and were followed up for one year at the Manhiça District Hospital in Mozambique. Ten plasma and 12 stool biomarkers were quantified by Luminex or ELISA and levels were compared to CHI-naive (n = 26), CHI on antiretroviral-treatment (ART; n = 30) and HIV-uninfected individuals (n = 58). Regression models adjusted by time point were used to estimate the association of the biomarkers with HIV-disease markers. Receiver operating curves were compared for the best accuracy to distinguish PHI from CHI.

Results

Soluble (s)CD14 was significantly associated with the CD4/CD8 ratio (P < 0.05) and viremia levels (P < 0.0001) during PHI. Plasma zonulin and stool lactoferrin were significantly higher in PHI as compared to CHI-individuals (P < 0.05). Plasma zonulin demonstrated the best accuracy to identify PHI among HIV-infected individuals (AUC = 0.85 [95% CI 0.75–0.94]). Using a cutoff value of plasma zonulin ≥ 8.75 ng/mL the model identified PHI with 87.7% sensitivity (95% CI 76.3–94.9) and 69.2% specificity (95% CI 48.2–85.7). An adjusted multivariate model including age, plasma zonulin and sCD14 further increased the classification performance (AUC = 0.92 [95% CI 0.86–0.99]).

Conclusions

While the stool biomarkers did not provide any predictive ability to distinguish PHI from CHI-individuals, plasma sCD14 and zonulin were significantly associated with HIV-disease markers and PHI identification, respectively. These inflammatory biomarkers may be useful to monitor changes in gastrointestinal integrity during HIV infection.

HIV-1 Envelope Glycoproteins Induce the Production of TNF-α and IL-10 in Human Monocytes by Activating Calcium Pathway

Human HIV-1 infection leads inevitably to a chronic hyper-immune-activation. However, the nature of the targeted receptors and the pathways involved remain to be fully elucidated. We demonstrate that X4-tropic gp120 induced the production of TNF-α and IL-10 by monocytes through activation of a cell membrane receptor, distinct from the CD4, CXCR4, and MR receptors. Gp120 failed to stimulate IL-10 and TNF-α production by monocytes in Ca²⁺ free medium. This failure was total for IL-10 and partial for TNF-α. However, IL-10 and TNF-α production was fully restored following the addition of exogenous calcium. Accordingly, addition of BAPTA-AM and cyclosporine-A, fully and partially inhibited IL-10 and TNF-α respectively. The PKA pathway was crucial for IL-10 production but only partially involved in gp120-induced TNF-α. The PLC pathway was partially and equivalently involved in gp120-induced TNF-α and IL-10. Moreover, the inhibition of PI3K, ERK1/2, p38 MAP-kinases and NF-κB pathways totally abolished the production of both cytokines. In conclusion, this study revealed the crucial calcium signaling pathway triggered by HIV-1 gp120 to control the production of these two cytokines: TNF-α and IL-10. The finding could help in the development of a new therapeutic strategy to alleviate the chronic hyper-immune-activation observed in HIV-1 infected patients.

Biomarkers of Progression after HIV Acute/Early Infection: Nothing Compares to CD4⁺ T-cell Count?

Progression of HIV infection is variable among individuals, and definition disease progression biomarkers is still needed. Here, we aimed to categorize the predictive potential of several variables using feature selection methods and decision trees. A total of seventy-five treatment-naïve subjects were enrolled during acute/early HIV infection. CD4⁺ T-cell counts (CD4TC) and viral load (VL) levels were determined at enrollment and for one year. Immune activation, HIV-specific immune response, Human Leukocyte Antigen (HLA) and C-C chemokine receptor type 5 (CCR5) genotypes, and plasma levels of 39 cytokines were determined. Data were analyzed by machine learning and non-parametric methods. Variable hierarchization was performed by Weka correlation-based feature selection and J48 decision tree. Plasma interleukin (IL)-10, interferon gamma-induced protein (IP)-10, soluble IL-2 receptor alpha (sIL-2Rα) and tumor necrosis factor alpha (TNF-α) levels correlated directly with baseline VL, whereas IL-2, TNF-α, fibroblast growth factor (FGF)-2 and macrophage inflammatory protein (MIP)-1β correlated directly with CD4⁺ T-cell activation (p < 0.05). However, none of these cytokines had good predictive values to distinguish "progressors" from "non-progressors". Similarly, immune activation, HIV-specific immune responses and HLA/CCR5 genotypes had low discrimination power. Baseline CD4TC was the most potent discerning variable with a cut-off of 438 cells/μL (accuracy = 0.93, κ-Cohen = 0.85). Limited discerning power of the other factors might be related to frequency, variability and/or sampling time. Future studies based on decision trees to identify biomarkers of post-treatment control are warrantied.

Dynamics of CD4 and CD8 T-Cell Subsets and Inflammatory Biomarkers during Early and Chronic HIV Infection in Mozambican Adults

During primary HIV infection (PHI), there is a striking cascade response of inflammatory cytokines and many cells of the immune system show altered frequencies and signs of extensive activation. These changes have been shown to have a relevant role in predicting disease progression; however, the challenges of identifying PHI have resulted in a lack of critical information about the dynamics of early pathogenic events. We studied soluble inflammatory biomarkers and changes in T-cell subsets in individuals at PHI (n = 40), chronic HIV infection (CHI, n = 56), and HIV-uninfected (n = 58) recruited at the Manhiça District Hospital in Mozambique. Plasma levels of 49 biomarkers were determined by Luminex and ELISA. T-cell immunophenotyping was performed by multicolor flow cytometry. Plasma HIV viremia, CD4, and CD8 T cell counts underwent rapid stabilization after PHI. However, several immunological parameters, including Th1-Th17 CD4 T cells and activation or exhaustion of CD8 T cells continued decreasing until more than 9 months postinfection. Importantly, no sign of immunosenescence was observed over the first year of HIV infection. Levels of IP-10, MCP-1, BAFF, sCD14, tumor necrosis factor receptor-2, and TRAIL were significantly overexpressed at the first month of infection and underwent a prompt decrease in the subsequent months while, MIG and CD27 levels began to increase 1 month after infection and remained overexpressed for almost 1 year postinfection. Early levels of soluble biomarkers were significantly associated with subsequently exhausted CD4 T-cells or with CD8 T-cell activation. Despite rapid immune control of virus replication, the stabilization of the T-cell subsets occurs months after viremia and CD4 count plateau, suggesting persistent immune dysfunction and highlighting the potential benefit of early treatment initiation that could limit immunological damage.

Chemokines and Chemokine Receptors: Accomplices for Human Immunodeficiency Virus Infection and Latency

Chemokines are small chemotactic cytokines that are involved in the regulation of immune cell migration. Multiple functional properties of chemokines, such as pro-inflammation, immune regulation, and promotion of cell growth, angiogenesis, and apoptosis, have been identified in many pathological and physiological contexts. Human immunodeficiency virus (HIV) infection is characterized by persistent inflammation and immune activation during both acute and chronic phases, and the "cytokine storm" is one of the hallmarks of HIV infection. Along with immune activation after HIV infection, an extensive range of chemokines and other cytokines are elevated, thereby generating the so-called "cytokine storm." In this review, the effects of the upregulated chemokines and chemokine receptors on the processes of HIV infection are discussed. The objective of this review was to focus on the main chemokines and chemokine receptors that have been found to be associated with HIV infection and latency. Elevated chemokines and chemokine receptors have been shown to play important roles in the HIV life cycle, disease progression, and HIV reservoir establishment. Thus, targeting these chemokines and receptors and the other proteins of related signaling pathways might provide novel therapeutic strategies, and the evidence indicates a promising future regarding the development of a functional cure for HIV.

On-chip immune cell activation and subsequent time-resolved magnetic bead-based cytokine detection

Cytokine profiling and immunophenotyping offer great potential for understanding many disease mechanisms, personalized diagnosis, and immunotherapy. Here, we demonstrate a time-resolved detection of cytokine from a single cell cluster using an in situ magnetic immune assay. An array of triple-layered microfluidic chambers was fabricated to enable simultaneous cell culture under perfusion flow and detection of the induced cytokines at multiple time-points. Each culture chamber comprises three fluidic compartments which are dedicated to, cell culture, perfusion and immunoassay. The three compartments are separated by porous membranes, which allow the diffusion of fresh nutrient from the perfusion compartment into the cell culture compartment and cytokines secretion from the cell culture compartment into the immune assay compartment. This structure hence enables capturing the released cytokines without disturbing the cell culture and without minimizing benefit gain from perfusion. Functionalized magnetic beads were used as a solid phase carrier for cytokine capturing and quantification. The cytokines released from differential stimuli were quantified in situ in non-differentiated U937 monocytes and differentiated macrophages.

Early initiation of antiretroviral treatment postSIV infection does not resolve lymphoid tissue activation

OBJECTIVE

Germinal center resident follicular helper T (TFH) cells in lymphoid follicles are a potential sanctuary for HIV/simian immunodeficiency virus (SIV) replication. But the dynamics of germinal centers upon early initiation of antiretroviral therapy (ART) and their potential role in the formation of viral sanctuaries post-SIV infection are not fully understood.

DESIGN

Sequential lymph node biopsies (n = 10) were collected from SIVmac239-infected rhesus macaques before infection, at 5 weeks postinfection/pre-ART, 6 and 12 weeks following ART initiation. These tissues and cells were analyzed for frequencies of TFH cells and assignment of germinal center scores.

RESULTS

Modest but significant increases in TFH cells and hyperplastic follicles with large germinal centers were noted during the acute phase of SIV infection (week 5/pre-ART). However, 6 weeks after ART initiation, substantial increases in germinal center TFH cells, germinal center B cells, hyperplastic follicles with large germinal centers, and abundant local IL-21 production were observed, whereas levels of SIV RNA and DNA of lymph nodes had decreased to barely detectable values along with barely detectable levels of SIV antibody-producing cells. An additional 6 weeks of ART did not appreciably decrease germinal center TFH or germinal center scores.

CONCLUSION

Thus, although early ART rapidly controls SIV replication, it does not regulate early lymphoid activation, which may contribute to the seeding and magnitude of viral reservoirs.

IP-10 Levels as an Accurate Screening Tool to Detect Acute HIV Infection in Resource-Limited Settings

Acute HIV infection (AHI) is the period prior to seroconversion characterized by high viral replication, hyper-transmission potential and commonly, non-specific febrile illness. AHI detection requires HIV-RNA viral load (VL) determination, which has very limited access in low-income countries due to restrictive costs and implementation constraints. We sought to identify a biomarker that could enable AHI diagnosis in scarce-resource settings, and to evaluate the feasibility of its implementation. HIV-seronegative adults presenting at the Manhiça District Hospital, Mozambique, with reported-fever were tested for VL. Plasma levels of 49 inflammatory biomarkers from AHI (n = 61) and non-HIV infected outpatients (n = 65) were determined by Luminex and ELISA. IP-10 demonstrated the best predictive power for AHI detection (AUC = 0.88 [95%CI 0.80-0.96]). A cut-off value of IP-10 ≥ 161.6 pg/mL provided a sensitivity of 95.5% (95%CI 85.5-99.5) and a specificity of 76.5% (95%CI 62.5-87.2). The implementation of an IP-10 screening test could avert from 21 to 84 new infections and save from US$176,609 to US$533,467 to the health system per 1,000 tested patients. We conclude that IP-10 is an accurate biomarker to screen febrile HIV-seronegative individuals for subsequent AHI diagnosis with VL. Such an algorithm is a cost-effective strategy to prevent disease progression and a substantial number of further HIV infections.

Comparative evaluation of microbial translocation products (LPS, sCD14, IgM Endocab) in HIV-1 infected Indian individuals

BACKGROUND

Microbial translocation of lipopolysaccharides (LPS), soluble CD14 (sCD14) and IgM Endocab levels have been reported to be associated with disease progression in HIV-1 infection. In this longitudinal study, plasma levels of different microbially translocated products (LPS, sCD14, Endocab) was investigated in HIV-1 infected Indian Individuals stratified as Rapid (R), Viremic slow (VS), Slow progressors (S) and healthy controls.

METHOD

Ten healthy and twenty HIV-1 infected individuals were enrolled. Plasma levels of LPS, sCD14, Endocab was examined using commercially available Limulus Amebocyte assay and enzyme-linked immunosorbent assay (ELISA) enzyme linked immunosorbant assay.

RESULTS

Elevated levels of sCD14, IgM EndoCab and LPS were observed during HIV-1 infection compared to healthy controls. Rapid progressors had higher levels of sCD14, IgM EndoCab, LPS (median% 1553, 3596, 202.2) compared to viremic slow, slow progressors and healthy controls both at baseline and follow up visits. At baseline, LPS correlated positively with IgM Endocab and negatively with sCD14 levels while at follow-up, significant positive correlation was observed between IgM Endocab and sCD14 (IgM EndoCab r = 0.490, p = 0.05; sCD14 r = 0.051, p = 0.830). Plasma levels of sCD14 correlated positively with viral load in rapid, viremic slow and slow progressors while CD + T cell count correlated positively with sCD14 and IgM EndoCab levels in viremic slow and slow progressors.

CONCLUSION

Our findings indicate that elevated levels of sCD14, IgM EndoCab and LPS in HIV-1 infected individuals are strong predictors of disease progression and could be considered as candidate biomarkers for disease monitoring.

Insulin Treatment Prevents Neuroinflammation and Neuronal Injury with Restored Neurobehavioral Function in Models of HIV/AIDS Neurodegeneration

HIV-1 infection of the brain causes the neurodegenerative syndrome HIV-associated neurocognitive disorders (HAND), for which there is no specific treatment. Herein, we investigated the actions of insulin using ex vivo and in vivo models of HAND. Increased neuroinflammatory gene expression was observed in brains from patients with HIV/AIDS. The insulin receptor was detected on both neurons and glia, but its expression was unaffected by HIV-1 infection. Insulin treatment of HIV-infected primary human microglia suppressed supernatant HIV-1 p24 levels, reduced CXCL10 and IL-6 transcript levels, and induced peroxisome proliferator-activated receptor gamma (PPAR-γ) expression. Insulin treatment of primary human neurons prevented HIV-1 Vpr-mediated cell process retraction and death. In feline immunodeficiency virus (FIV) infected cats, daily intranasal insulin treatment (20.0 IU/200 μl for 6 weeks) reduced CXCL10, IL-6, and FIV RNA detection in brain, although PPAR-γ in glia was increased compared with PBS-treated FIV⁺ control animals. These molecular changes were accompanied by diminished glial activation in cerebral cortex and white matter of insulin-treated FIV⁺ animals, with associated preservation of cortical neurons. Neuronal counts in parietal cortex, striatum, and hippocampus were higher in the FIV⁺/insulin-treated group compared with the FIV⁺/PBS-treated group. Moreover, intranasal insulin treatment improved neurobehavioral performance, including both memory and motor functions, in FIV⁺ animals. Therefore, insulin exerted ex vivo and in vivo antiviral, anti-inflammatory, and neuroprotective effects in models of HAND, representing a new therapeutic option for patients with inflammatory or infectious neurodegenerative disorders including HAND.

SIGNIFICANCE STATEMENT

HIV-associated neurocognitive disorders (HAND) represent a spectrum disorder of neurocognitive dysfunctions resulting from HIV-1 infection. Although the exact mechanisms causing HAND are unknown, productive HIV-1 infection in the brain with associated neuroinflammation is a potential pathogenic mechanism resulting in neuronal damage and death. We report that, in HIV-infected microglia cultures, insulin treatment led to reduced viral replication and inflammatory gene expression. In addition, intranasal insulin treatment of experimentally feline immunodeficiency virus-infected animals resulted in improved motor and memory performances. We show that insulin restored expression of the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-γ), which is suppressed by HIV-1 replication. Our findings indicate a unique function for insulin in improving neurological outcomes in lentiviral infections, implicating insulin as a therapeutic intervention for HAND.

A Cytokine Pattern That Differentiates Preseroconversion From Postseroconversion Phases of Primary HIV Infection

BACKGROUND

During acute HIV infection, HIV actively replicates but seroconversion has not yet occurred. Primary HIV infection (PHI) is characterized by a transient nonspecific febrile illness, a massive inflammatory response, and the progressive appearance of anti-HIV-specific antibodies. In this study, we have identified patterns of inflammatory biomarkers associated with the innate immunological reaction before completion of a full humoral response.

METHODS

A symptom-based screening was used to identify acute HIV infection in the Manhiça District Hospital in Mozambique. Plasma levels of biomarkers were determined by Luminex and enzyme-linked immunosorbent assay. Anti-HIV antibodies were analyzed by flow cytometry and Western blot. Statistical analyses used random forest and logistic regression models.

RESULTS

Of 3116 rapid test seronegative or indeterminate individuals, 85 (2.7%) had positive plasma HIV viral load and were enrolled as PHI, of which n = 45 (52.9%), n = 8 (9.4%), n = 12 (14.1%), and n = 20 (23.5%) were classified as Fiebig I-III, IV, V, and VI stages, respectively, by Western blot. Comparison of individuals at early (Fiebig I-IV) and late (Fiebig V-VI) immune stages identified significant differences in the expression level of plasma B-cell activating factor , monocyte chemotactic protein-1, sCD163, and monokine induced by interferon (IFN-γ). This cytokine signature classified patients in the preseroconversion phase with a sensitivity of 92.5% and a specificity of 81.2% CONCLUSIONS:: Identification of a cytokine signature specific for the preseroconversion stage of PHI may help to understand the earliest HIV pathogenic events and identify new potential targets for immunotherapy aimed at modulating the cytokine response to HIV infection.

IFN- protects primary macrophages against HIV infection

IFN-ε is a unique type I IFN that is not induced by pattern recognition response elements. IFN-ε is constitutively expressed in mucosal tissues, including the female genital mucosa. Although the direct antiviral activity of IFN-ε was thought to be weak compared with IFN-α, IFN-ε controls Chlamydia muridarum and herpes simplex virus 2 in mice, possibly through modulation of immune response. We show here that IFN-ε induces an antiviral state in human macrophages that blocks HIV-1 replication. IFN-ε had little or no protective effect in activated CD4⁺ T cells or transformed cell lines unless activated CD4⁺ T cells were infected with replication-competent HIV-1 at a low MOI. The block to HIV infection of macrophages was maximal after 24 hours of treatment and was reversible. IFN-ε acted on early stages of the HIV life cycle, including viral entry, reverse transcription, and nuclear import. The protection did not appear to operate through known type I IFN-induced HIV host restriction factors, such as APOBEC3A and SAMHD1. IFN-ε-stimulated immune mediators and pathways had the signature of type I IFNs but were distinct from IFN-α in macrophages. IFN-ε induced significant phagocytosis and ROS, which contributed to the block to HIV replication. These findings indicate that IFN-ε induces an antiviral state in macrophages that is mediated by different factors than those induced by IFN-α. Understanding the mechanism of IFN-ε-mediated HIV inhibition through immune modulation has implications for prevention.

Magnitude and Quality of Cytokine and Chemokine Storm during Acute Infection Distinguish Nonprogressive and Progressive Simian Immunodeficiency Virus Infections of Nonhuman Primates

Acute human immunodeficiency virus (HIV) infection represents a period of intense immune perturbation and activation of the host immune system. Study of the eclipse and viral expansion phases of infection is difficult in humans, but studies in nonprogressive and progressive nonhuman primate (NHP) infection models can provide significant insight into critical events occurring during this time. Cytokines, chemokines, and other soluble immune factors were measured in longitudinal samples from rhesus macaques infected with either SIVmac251 (progressive infection) or SIVmac239Δnef (attenuated/nonprogressive infection) and from African green monkeys infected with SIVsab9315BR (nonpathogenic infection). Levels of acute-phase peak viral replication were highest in SIVmac251 infection but correlated positively with viremia at 3 months postinfection in all three infection models. SIVmac251 infection was associated with stronger corresponding acute-phase cytokine/chemokine responses than the nonprogressive infections. The production of interleukin 15 (IL-15), IL-18, gamma interferon (IFN-γ), granulocyte colony-stimulating factor (G-CSF), monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein 1β (MIP-1β), and serum amyloid A protein (SAA) during acute SIVmac251 infection, but not during SIVmac239Δnef or SIVsab9315BR infection, correlated positively with chronic viremia at 3 months postinfection. Acute-phase production of MCP-1 correlated with viremia at 3 months postinfection in both nonprogressive infections. Finally, a positive correlation between the acute-phase area under the curve (AUC) for IL-6 and soluble CD40 ligand (sCD40L) and chronic viremia was observed only for the nonprogressive infection models. While we observed dynamic acute inflammatory immune responses in both progressive and nonprogressive SIV infections, the responses in the nonprogressive infections were not only lower in magnitude but also qualitatively different biomarkers of disease progression.

IMPORTANCE

NHP models of HIV infection constitute a powerful tool with which to study viral pathogenesis in order to gain critical information for a better understanding of HIV infection in humans. Here we studied progressive and nonprogressive simian immunodeficiency virus (SIV) infection models in both natural and nonnatural host NHP species. Regardless of the pathogenicity of the virus infection and regardless of the NHP species studied, the magnitude of viremia, as measured by area under the curve, during the first 4 weeks of infection correlated positively with viremia in chronic infection. The magnitude of cytokine and chemokine responses during primary infection also correlated positively with both acute-phase and chronic viremia. However, the pattern and levels of specific cytokines and chemokines produced differed between nonprogressive and progressive SIV infection models. The qualitative differences in the early immune response in pathogenic and nonpathogenic infections identified here may be important determinants of the subsequent disease course.

Cytokine cascade and networks among MSM HIV seroconverters: implications for early immunotherapy

The timing, intensity and duration of the cytokine cascade and reorganized interrelations in cytokine networks are not fully understood during acute HIV-1 infection (AHI). Using sequential plasma samples collected over three years post-infection in a cohort of MSM HIV-1 seroconvertors, we determined the early kinetics of cytokine levels during FiebigI-IV stages using Luminex-based multiplex assays. Cytokines were quantified and relationships between cytokines were assessed by Spearman correlation. Compared with HIV-negative MSM, HIV-infected individuals had significantly increased multiple plasma cytokines, including GM-CSF, IFN-α2, IL-12p70, IP-10 and VEGF, during both acute and chronic stages of infection. Furthermore, rapid disease progressors (RDPs) had earlier and more robust cytokine storms, compared with slow disease progressors (SDPs) (49.6 days vs. 74.9 days, respectively; 6.7-fold vs. 3.7-fold change of cytokines, respectively), suggesting the faster and stronger cytokine storm during AHI could promote disease progression. On the other hand, HIV-1 infection induced more interlocked cytokines network, establishing new strong correlations and imposing a higher rigidity. There were, respectively, 146 (44.9%) statistically significant correlations of cytokines in RDPs and 241 (74.2%) in SDPs (p < 0.001). This study suggests that immunomodulatory interventions aimed at controlling cytokine storm in AHI may be beneficial to slow eventual disease progression.

Characterization of Simian Immunodeficiency Virus Variants Anatomically Compartmentalized in Plasma and Milk in Chronically Infected African Green Monkeys

Unlike human immunodeficiency virus type 1 (HIV-1)-infected humans, African-origin, natural simian immunodeficiency virus (SIV) hosts, such as African green monkeys (AGMs), sustain nonpathogenic SIV infections and rarely vertically transmit SIV to their infants. Interestingly, chronically SIV-infected AGMs have anatomically compartmentalized SIV variants in plasma and milk, whereas humans and SIV-infected rhesus monkeys (RMs), Asian-origin nonnatural SIV hosts, do not exhibit this compartmentalization. Thus, it is possible that AGM SIV populations in milk have unique phenotypic features that contribute to the low postnatal transmission rates observed in this natural host species. In this study, we explored this possibility by characterizing the infectivity, tropism, and neutralization susceptibility of plasma and milk SIVsab env variants isolated from chronically SIVsab92018ivTF-infected AGMs. AGM plasma and milk SIVsab env pseudovirus variants exhibited similar infectivities, neutralization susceptibilities to autologous and heterologous plasma, and chemokine coreceptor usages for cell entry, suggesting similar abilities to initiate infection in a new host. We also assessed the cytokine milieu in SIV-infected AGM milk and compared it to that of SIV-infected RMs. MIP-1β, granulocyte colony-stimulating factor (G-CSF), interleukin-12/23 (IL-12/23), and IL-13 trended significantly higher in SIV-infected AGM milk than in that of RMs, while IL-18 and IL-6 trended significantly higher in SIV-infected RM milk than in that of AGMs. Taken together, our findings imply that nonviral maternal factors, such as the cytokine milieu, rather than unique characteristics of SIV populations in the milk contribute to the low postnatal transmission rates observed in AGMs.

IMPORTANCE

Due to the ongoing global incidence of pediatric HIV-1 infections, including many that occur via breastfeeding, development of effective vaccine strategies capable of preventing vertical HIV transmission through breastfeeding remains an important goal. Unlike HIV-1-infected humans, African green monkeys (AGMs), the natural SIV host species, sustain nonpathogenic SIV infections, rarely transmit the virus postnatally to their infants, and exhibit anatomically compartmentalized SIV populations in milk and plasma. Identifying unique features of the anatomically compartmentalized milk SIV populations could enhance our understanding of how AGMs may have evolved to avoid transmission through breastfeeding. While this study identified limited phenotypic distinctions between AGM plasma and milk SIV populations, potential differences in milk cytokine profiles of natural and nonnatural SIV hosts were observed. These findings imply the potential importance of nonviral factors in natural SIV host species, such as innate SIV/HIV immune factors in milk, as a means of naturally preventing vertical transmission.

The comparison of Th1, Th2, Th9, Th17 and Th22 cytokine profiles in acute and chronic HIV-1 infection

The aim of this study was to compare cytokine expression on both gene and protein levels in acute and chronic phase of HIV type 1 (HIV-1) infection. Thirty four patients were enrolled for cytokine expression analysis on protein level in acute and chronic stage of HIV-1 infection. Using PCR array technology, expression of 84 cytokine genes was measured in 3 patients in acute and 3 patients in chronic stage of HIV-1 infection. Bead-based cytometry was used to quantify levels of Th1/Th2/Th9/Th17/Th22 cytokines. The results showed statistically significant increase of 13 cytokine gene expression (cd40lg, csf2, ifna5, il12b, il1b, il20, lta, osm, spp1, tgfa, tnfsf 11, 14 and 8) and downregulation of the il12a expression in chronic HIV type 1 infection. Concentrations of IL-10, IL-4 and TNF-α were increased in the acute HIV type 1 infection when compared to control group. During chronic HIV type 1 infection there was an increase of IL-10, TNF-α, IL-2, IL-6, IL-13 and IL-22 levels when compared to control group. Comparison of cytokine expression between two stages of infection showed a significant decrease in IL-9 concentration. This study showed changes in cytokine profiles on both gene and protein levels in different stages of HIV-infection.

Rapid and Slow Progressors Show Increased IL-6 and IL-10 Levels in the Pre-AIDS Stage of HIV Infection

Cytokines are intrinsically related to disease progression in HIV infection. We evaluated the plasma levels of Th1/Th2/Th17 cytokines in extreme progressors, including slow (SPs) and rapid (RPs) progressors, who were thus classified based on clinical and laboratory follow-up covering a period of time before the initiation of HAART, ranging from 93–136.5 months for SPs and 7.5–16.5 months for RPs. Analyses were also performed based on the different stages of HIV infection (chronic, pre-HAART individuals—subjects sampled before initiating HAART but who initiated therapy from 12 to 24 months—and those receiving HAART). The plasma cytokine levels of 16 HIV-infected rapid progressors and 25 slow progressors were measured using a Human Th1/Th2/Th17 CBA kit. The IL-6 and IL-10 plasma levels differed significantly between the stages of HIV infection. The IL-6 levels were higher in slow progressors pre-HAART than in chronically infected SPs and HIV-seronegative individuals. The IL-10 levels were higher in slow progressors pre-HAART than in slow progressors receiving HAART and HIV-seronegative controls, and in rapid progressors, the IL-10 levels were higher in pre-HAART subjects than in HIV-seronegative controls. The results reflect the changes in the cytokine profile occurring during different clinical stages in HIV+ subjects. Our results suggest an association between increased IL-6 and IL-10 levels and pre-HAART stages independent of the slow or rapid progression status of the subjects. Thus, increased IL-6 and IL-10 levels could indicate a global inflammatory status and could be used as markers of the disease course in HIV-infected individuals.

Plasma Cytokine Levels in Chronic Asymptomatic HIV-1 Subtype C Infection as an Indicator of Disease Progression in Botswana: A Retrospective Case Control Study

HIV infects cells of the immune system causing immune activation and proliferation of immune cells, leading to alteration of production and activity of a number of cytokines. These changes in cytokine levels can affect the immune function, and have the potential to directly impact the course of HIV disease. We characterized plasma cytokine concentration profiles in HIV-1 subtype C chronically infected, antiretroviral therapy (ART)-naive participants to establish their influence on disease progression and viremia. Plasma levels of interleukin (IL)-1α, IL-7, IL-12p40, granulocyte macrophage-colony-stimulating factor (GM-CSF), and interferon (IFN)-γ were quantified in samples from 60 treatment-naive participants in the placebo arm of the completed Micronutrient-HIV disease progressions study, "Dikotlana" (2004-2009) in Gaborone, Botswana. Participants were stratified into progressors (P) and nonprogressors (NP) based on their rates of CD4(+) T cell depletion during the study period. Nonprogressors were those who had <1% CD4(+) T cell depletion at 24 months postenrollment. Progressors were defined as those with CD4(+) T cell depletion of >15% at 24 months postenrollment. Cytokine levels were compared between P and NP using the Mann-Whitney U-test. Logistic regression analysis was used to determine if cytokines predicted disease progression. Correlations of cytokines with CD4(+) T cell counts and viral loads were determined by the Spearman rank test. Median baseline CD4(+) T cell counts were 453 (Q1, Q3; 401, 592) and 479 (Q1, Q3; 401-592) for nonprogressors and progressors, respectively. Nonprogressors had a higher viral set point than progressors. IL-12p40 levels were significantly higher in the P than in NP at enrollment and 24 months (p < 0.05). Levels of IL-1α, IL-7, IFN-γ, and GM-CSF did not differ significantly between the two groups. Except for IL-12p40, which displayed an inverse correlation with CD4(+) T cell counts and a direct correlation with viral load, all other cytokines showed no correlations. IL-12p40 was found to be the most significant predictor of progression and its production was most likely driven by HIV replication products as evidenced by its direct correlation with viral load. In chronic HIV-1 subtype C infection, CD4(+) T cell counts and plasma cytokine levels may not necessarily evolve in parallel, suggesting the involvement of other factors in determining the rates of CD4(+) T cell depletion.

Reconciling Longitudinal Naive T-Cell and TREC Dynamics during HIV-1 Infection

Naive T cells in untreated HIV-1 infected individuals have a reduced T-cell receptor excision circle (TREC) content. Previous mathematical models have suggested that this is due to increased naive T-cell division. It remains unclear, however, how reduced naive TREC contents can be reconciled with a gradual loss of naive T cells in HIV-1 infection. We performed longitudinal analyses in humans before and after HIV-1 seroconversion, and used a mathematical model to investigate which processes could explain the observed changes in naive T-cell numbers and TRECs during untreated HIV-1 disease progression. Both CD4⁺ and CD8⁺ naive T-cell TREC contents declined biphasically, with a rapid loss during the first year and a much slower loss during the chronic phase of infection. While naive CD8⁺ T-cell numbers hardly changed during follow-up, naive CD4⁺ T-cell counts continually declined. We show that a fine balance between increased T-cell division and loss in the peripheral naive T-cell pool can explain the observed short- and long-term changes in TRECs and naive T-cell numbers, especially if T-cell turnover during the acute phase is more increased than during the chronic phase of infection. Loss of thymic output, on the other hand, does not help to explain the biphasic loss of TRECs in HIV infection. The observed longitudinal changes in TRECs and naive T-cell numbers in HIV-infected individuals are most likely explained by a tight balance between increased T-cell division and death, suggesting that these changes are intrinsically linked in HIV infection.

Modulation of apoptosis and viral latency - an axis to be well understood for successful cure of human immunodeficiency virus

Human immunodeficiency virus (HIV) is the causative agent of the deadly disease AIDS, which is characterized by the progressive decline of CD4(+)T-cells. HIV-1-encoded proteins such as envelope gp120 (glycoprotein gp120), Tat (trans-activator of transcription), Nef (negative regulatory factor), Vpr (viral protein R), Vpu (viral protein unique) and protease are known to be effective in modulating host cell signalling pathways that lead to an alteration in apoptosis of both HIV-infected and uninfected bystander cells. Depending on the stage of the virus life cycle and host cell type, these viral proteins act as mediators of pro- or anti-apoptotic signals. HIV latency in viral reservoirs is a persistent phenomenon that has remained beyond the control of the human immune system. To cure HIV infections completely, it is crucial to reactivate latent HIV from cellular pools and to drive these apoptosis-resistant cells towards death. Several previous studies have reported the role of HIV-encoded proteins in apoptosis modulation, but the molecular basis for apoptosis evasion of some chronically HIV-infected cells and reactivated latently HIV-infected cells still needs to be elucidated. The current review summarizes our present understanding of apoptosis modulation in HIV-infected cells, uninfected bystander cells and latently infected cells, with a focus on highlighting strategies to activate the apoptotic pathway to kill latently infected cells.

Defective iron homeostasis in human immunodeficiency virus type-1 latency

Highly active antiretroviral therapy has significantly improved the life of HIV-1-infected individuals, yet complete eradication of HIV-1 reservoirs (i.e., latently infected cells) remains a major challenge. We have previously shown that induction of the endogenous cytoprotective enzyme heme oxygenase-1 (HO-1) by its natural substrate hemin reduces susceptibility of T cells and macrophages to HIV-1 infection. In the present study, we demonstrate that hemin treatment stimulated virus production by latently infected ACH-2 cells, followed by cellular toxicity and death when stimulated with TNF-α or co-cultured with monocyte-derived macrophages (MDM). This cytotoxicity was associated with low levels of the iron-binding protein ferritin and the iron transporter ferroportin with lack of hemoglobin catabolic enzyme HO-1, resulting in substantial iron accumulation in the activated ACH-2 cells. Defective iron homeostasis in ACH-2 cells provides a model system for selective targeting of the latent HIV-1 reservoir by hemin-induced iron toxicity.

Comparative Analysis of Tat-Dependent and Tat-Deficient Natural Lentiviruses

The emergence of human immunodeficiency virus (HIV) causing acquired immunodeficiency syndrome (AIDS) in infected humans has resulted in a global pandemic that has killed millions. HIV-1 and HIV-2 belong to the lentivirus genus of the Retroviridae family. This genus also includes viruses that infect other vertebrate animals, among them caprine arthritis-encephalitis virus (CAEV) and Maedi-Visna virus (MVV), the prototypes of a heterogeneous group of viruses known as small ruminant lentiviruses (SRLVs), affecting both goat and sheep worldwide. Despite their long host-SRLV natural history, SRLVs were never found to be responsible for immunodeficiency in contrast to primate lentiviruses. SRLVs only replicate productively in monocytes/macrophages in infected animals but not in CD4+ T cells. The focus of this review is to examine and compare the biological and pathological properties of SRLVs as prototypic Tat-independent lentiviruses with HIV-1 as prototypic Tat-dependent lentiviruses. Results from this analysis will help to improve the understanding of why and how these two prototypic lentiviruses evolved in opposite directions in term of virulence and pathogenicity. Results may also help develop new strategies based on the attenuation of SRLVs to control the highly pathogenic HIV-1 in humans.

Effect of Probiotic Supplement on Cytokine Levels in HIV-Infected Individuals: A Preliminary Study

Inflammation persists in patients infected with HIV. Reduction of inflammatory cytokines and microbial translocation might be one way that this could be managed. Purpose: The anti-inflammatory properties of certain probiotic strains prompted us to investigate whether a probiotic could reduce the inflammatory index of HIV-infected patients. Methods: The study involved 30 HIV+ males on antiretroviral therapy, who were given one bottle of fermented milk Yakult Light^® containing Lactobacillus casei Shirota (LcS) twice a day for four weeks. Results: The probiotic LcS was associated with an increase of T lymphocytes and a significant increase of CD56+ cells (p = 0.04). There was also a significant decrease of mRNA levels of TGFβ, IL-10 and IL-12 (p < 0.001) and IL-1β expression (p < 0.001) and an increase of serum IL-23 (p = 0.03). In addition, decreased inflammation and cardiovascular risk were observed, as shown by a reduction of cystatin C (p < 0.001). Conclusions: These data provide preliminary evidence that probiotic supplementation may modulate certain immunological parameters and some of the cytokines that were analyzed. Thus, we propose that LcS may be an inexpensive and practical strategy to support the immune function of HIV+ patients.

Impairment of T cell development and acute inflammatory response in HIV-1 Tat transgenic mice

Immune activation and chronic inflammation are hallmark features of HIV infection causing T-cell depletion and cellular immune dysfunction in AIDS. Here, we addressed the issue whether HIV-1 Tat could affect T cell development and acute inflammatory response by generating a transgenic mouse expressing Tat in lymphoid tissue. Tat-Tg mice showed thymus atrophy and the maturation block from DN4 to DP thymic subpopulations, resulting in CD4⁺ and CD8⁺ T cells depletion in peripheral blood. In Tat-positive thymus, we observed the increased p65/NF-κB activity and deregulated expression of cytokines/chemokines and microRNA-181a-1, which are involved in T-lymphopoiesis. Upon LPS intraperitoneal injection, Tat-Tg mice developed an abnormal acute inflammatory response, which was characterized by enhanced lethality and production of inflammatory cytokines. Based on these findings, Tat-Tg mouse could represent an animal model for testing adjunctive therapies of HIV-1-associated inflammation and immune deregulation.

PQBP1 Is a Proximal Sensor of the cGAS-Dependent Innate Response to HIV-1

Dendritic cells (DCs) play a critical role in the immune response to viral infection through the facilitation of cell-intrinsic antiviral activity and the activation of adaptive immunity. HIV-1 infection of DCs triggers an IRF3-dependent innate immune response, which requires the activity of cyclic GAMP synthase (cGAS). We report the results of a targeted RNAi screen utilizing primary human monocyte-derived DCs (MDDCs) to identify immune regulators that directly interface with HIV-1-encoded features to initiate this innate response. Polyglutamine binding protein 1 (PQBP1) emerged as a strong candidate through this analysis. We found that PQBP1 directly binds to reverse-transcribed HIV-1 DNA and interacts with cGAS to initiate an IRF3-dependent innate response. MDDCs derived from Renpenning syndrome patients, who harbor mutations in the PQBP1 locus, possess a severely attenuated innate immune response to HIV-1 challenge, underscoring the role of PQBP1 as a proximal innate sensor of a HIV-1 infection.

Fast disease progression in simian HIV-infected female macaque is accompanied by a robust local inflammatory innate immune and microbial response

OBJECTIVE

Gender differences in immune response and the rate of disease progression in HIV-infected individuals have been reported but the underlying mechanism remains unclear, in part because of the lack of relevant animal models. Here, we report a novel nonhuman primate model for investigation of sex disparity in HIV disease progression.

DESIGN/METHODS

Viral load and rate of disease progression were evaluated in rhesus macaques infected intrarectally with lineage-related subtype C R5 simian HIVs. Cytokine/chemokine levels in rectal swab eluates, and bacterial species adherent to the swabs and in the feces were determined.

RESULTS

Simian HIV-infected female rhesus macaques progressed faster to AIDS than male macaques, recapitulating the sex bias in HIV-1 disease in humans. There were no significant differences in the levels of soluble immune mediators in the rectal mucosa of naive female and male macaques. However, an exploratory longitudinal study in six infected macaques indicates that the female macaques mounted an earlier and more robust proinflammatory skewed rectal immune response to infection. Moreover, expansion of Proteobacteria that increase in other intestinal inflammatory disorders was significantly higher in the rectal mucosa of female than male macaques during acute infection.

CONCLUSION

These findings suggest that sex differences in local innate immune activation and compositional shifts in the gut microbiota could be the drivers of increased disease susceptibility in female macaques. Further studies with this novel nonhuman primate model of HIV infection could lead to innovative research on gender differences, which may have important therapeutic implications for controlling disease in infected men as well as women.

Multiplexed Component Analysis to Identify Genes Contributing to the Immune Response during Acute SIV Infection

Immune response genes play an important role during acute HIV and SIV infection. Using an SIV macaque model of AIDS and CNS disease, our overall goal was to assess how the expression of genes associated with immune and inflammatory responses are longitudinally changed in different organs or cells during SIV infection. To compare RNA expression of a panel of 88 immune-related genes across time points and among three tissues – spleen, mesenteric lymph nodes (MLN) and peripheral blood mononuclear cells (PBMC) – we designed a set of Nanostring probes. To identify significant genes during acute SIV infection and to investigate whether these genes are tissue-specific or have global roles, we introduce a novel multiplexed component analysis (MCA) method. This combines multivariate analysis methods with multiple preprocessing methods to create a set of 12 “judges”; each judge emphasizes particular types of change in gene expression to which cells could respond, for example, the absolute or relative size of expression change from baseline. Compared to bivariate analysis methods, our MCA method improved classification rates. This analysis allows us to identify three categories of genes: (a) consensus genes likely to contribute highly to the immune response; (b) genes that would contribute highly to the immune response only if certain assumptions are met – e.g. that the cell responds to relative expression change rather than absolute expression change; and (c) genes whose contribution to immune response appears to be modest. We then compared the results across the three tissues of interest; some genes are consistently highly-contributing in all tissues, while others are specific for certain tissues. Our analysis identified CCL8, CXCL10, CXCL11, MxA, OAS2, and OAS1 as top contributing genes, all of which are stimulated by type I interferon. This suggests that the cytokine storm during acute SIV infection is a systemic innate immune response against viral replication. Furthermore, these genes have approximately equal contributions to all tissues, making them possible candidates to be used as non-invasive biomarkers in studying PBMCs instead of MLN and spleen during acute SIV infection experiments. We identified clusters of genes that co-vary together and studied their correlation with regard to other gene clusters. We also developed novel methods to faithfully visualize multi-gene correlations on two-dimensional polar plots, and to visualize tissue specificity of gene expression responses.

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.

Transcriptional Regulation of CXCL5 in HIV-1-Infected Macrophages and Its Functional Consequences on CNS Pathology

Human immunodeficiency virus-1 (HIV-1)-infected monocytes/macrophages and microglia release increased levels of proinflammatory cytokines and chemokines, including ELR+ (containing glutamic acid-leucine-arginine motif) chemokines. To investigate the role of HIV-1 infection on chemokine regulation, monocyte-derived macrophages (MDMs) from normal donors were infected with HIV-1 and the expression of chemokines and their downstream biological functions were evaluated. Among the tested chemokines, CXCL5 was upregulated significantly both at the mRNA and protein level in the HIV-1-infected MDMs compared with mock-infected cultures. Upregulation of CXCL5 in the HIV-1-infected MDMs is, in part, regulated by increased interleukin-1β (IL-1β) production and phosphorylation of ERK1/2. Functional analyses indicate that HIV-1-induced overexpression of CXCL5 has enhanced the ability to attract neutrophils, as observed by chemotaxis assay. However, exposure of NT2, SH-SY5Y cells, and primary neurons to HIV-1-infected MDM supernatants resulted in cell death that was not rescued by anti-CXCL5 antibody suggesting that CXCL5 does not have direct effect on neuronal death. Together, these results suggest that the increased level of CXCL5 in tissue compartments, including the central nervous system of HIV-1-infected individuals might alter the inflammatory response through the infiltration of neutrophils into tissue compartment, thus causing secondary effects on resident cells.

Association of Cytokines With Exosomes in the Plasma of HIV-1-Seropositive Individuals

Human immunodeficiency virus (HIV)-infected and viremic individuals exhibit elevated levels of plasma cytokines. Here we show that most cytokines are not in free form but appear associated with exosomes that are distinct from virions. Purified exosomes were analyzed to determine the levels of 21 cytokines and chemokines and compared with exosome-depleted plasma. Most cytokines were markedly enriched in exosomes from HIV-positive individuals relative to negative controls and to plasma. Moreover, exposure of naive peripheral blood mononuclear cells to exosomes purified from HIV-positive patients induced CD38 expression on naive and central memory CD4(+) and CD8(+) T cells, probably contributing to inflammation and viral propagation via bystander cell activation.

HIV-1 Tat protein induces PD-L1 (B7-H1) expression on dendritic cells through tumor necrosis factor alpha- and toll-like receptor 4-mediated mechanisms

Chronic human immunodeficiency virus type 1 (HIV-1) infection is associated with induction of T-cell coinhibitory pathways. However, the mechanisms by which HIV-1 induces upregulation of coinhibitory molecules remain to be fully elucidated. The aim of the present study was to determine whether and how HIV-1 Tat protein, an immunosuppressive viral factor, induces the PD-1/PD-L1 coinhibitory pathway on human dendritic cells (DCs). We found that treatment of DCs with whole HIV-1 Tat protein significantly upregulated the level of expression of PD-L1. This PD-L1 upregulation was observed in monocyte-derived dendritic cells (MoDCs) obtained from either uninfected or HIV-1-infected patients as well as in primary myeloid DCs from HIV-negative donors. In contrast, no effect on the expression of PD-L2 or PD-1 molecules was detected. The induction of PD-L1 on MoDCs by HIV-1 Tat (i) occurred in dose- and time-dependent manners, (ii) was mediated by the N-terminal 1-45 fragment of Tat, (iii) did not require direct cell-cell contact but appeared rather to be mediated by soluble factor(s), (iv) was abrogated following neutralization of tumor necrosis factor alpha (TNF-α) or blocking of Toll-like receptor 4 (TLR4), (v) was absent in TLR4-knockoout (KO) mice but could be restored following incubation with Tat-conditioned medium from wild-type DCs, (vi) impaired the capacity of MoDCs to functionally stimulate T cells, and (vii) was not reversed functionally following PD-1/PD-L1 pathway blockade, suggesting the implication of other Tat-mediated coinhibitory pathways. Our results demonstrate that HIV-1 Tat protein upregulates PD-L1 expression on MoDCs through TNF-α- and TLR4-mediated mechanisms, functionally compromising the ability of DCs to stimulate T cells. The findings offer a novel potential molecular target for the development of an anti-HIV-1 treatment.

IMPORTANCE

The objective of this study was to investigate the effect of human immunodeficiency virus type 1 (HIV-1) Tat on the PD-1/PD-L1 coinhibitory pathway on human monocyte-derived dendritic cells (MoDCs). We found that treatment of MoDCs from either healthy or HIV-1-infected patients with HIV-1 Tat protein stimulated the expression of PD-L1. We demonstrate that this stimulation was mediated through an indirect mechanism, involving tumor necrosis factor alpha (TNF-α) and Toll-like receptor 4 (TLR4) pathways, and resulted in compromised ability of Tat-treated MoDCs to functionally stimulate T-cell proliferation.