Baseline Viral Load and Immune Activation Determine the Extent of Reconstitution of Innate Immune Effectors in HIV-1-Infected Subjects Undergoing Antiretroviral Treatment

Immune reconstitution efficacy after combination antiretroviral therapy in male HIV-1 infected patients with homosexual and heterosexual transmission

We aimed to explore the impact of sexual transmission modes on immune reconstitution after combined antiretroviral therapy (cART). We have retrospectively analyzed longitudinal samples from 1557 treated male patients with virological suppression (HIV-1 RNA<50 copies/ml) for at least 2 years. Both heterosexuals (HET) and men who have sex with men (MSM) patients showed an increasing annual trend in CD4⁺ T cell counts after receiving cART (HET, β: 23.51 (cell/µl)/year, 95% CI: 16.70 to 30.31; MSM, β: 40.21 (cell/µl)/year, 95% CI: 35.82 to 44.61). However, the CD4⁺ T cell recovery rate was much lower in HET patients than MSM patients, determined by both the generalized additive mixed model (P < 0.001) and generalized estimating equations (P = 0.026). Besides HIV-1 subtypes, baseline CD4⁺ T cell counts and age at cART initiation, HET was an independent risk factor for immunological non-responders (adjusted OR: 1.73; 95% CI: 1.28 to 2.33). HET was also associated with lower probability of achieving conventional immune recovery (adjusted HR: 1.37; 95%CI: 1.22 to 1.67) and optimal immune recovery (adjusted HR: 1.48, 95%CI: 1.04-2.11). Male HET patients might have poorer immune reconstitution ability even after effective cART. Early initiation of cART after diagnosis and clinical monitoring for male HET patients should be highly emphasized.

Human NK cells confer protection against HIV-1 infection in humanized mice

The role of NK cells against HIV-1 infections remains to be elucidated in vivo. While humanized mouse models potentially could be used to directly evaluate human NK cell responses during HIV-1 infection, improved functional development of human NK cells in these hosts is needed. Here, we report the humanized MISTRG-6-15 mouse model, in which NK cells were quick to expand and exhibit degranulation, cytotoxicity, and proinflammatory cytokine production in nonlymphoid organs upon HIV-1 infection but had reduced functionality in lymphoid organs. Although HIV-1 infection induced functional impairment of NK cells, antiretroviral therapy reinvigorated NK cells in response to HIV-1 rebound after analytic treatment interruption. Moreover, a broadly neutralizing antibody, PGT121, enhanced NK cell function in vivo, consistent with antibody-dependent cellular cytotoxicity. Monoclonal antibody depletion of NK cells resulted in higher viral loads in multiple nonlymphoid organs. Overall, our results in humanized MISTRG-6-15 mice demonstrated that NK cells provided direct anti-HIV-1 responses in vivo but were limited in their responses in lymphoid organs.

Natural killer cells during acute HIV-1 infection: clues for HIV-1 prevention and therapy

Despite progress in preexposure prophylaxis, the number of newly diagnosed cases with HIV-1 remains high, highlighting the urgent need for preventive and therapeutic strategies to reduce HIV-1 acquisition and limit disease progression. Early immunological events, occurring during acute infection, are key determinants of the outcome and course of disease. Understanding early immune responses occurring before viral set-point is established, is critical to identify potential targets for prophylactic and therapeutic approaches. Natural killer (NK) cells represent a key cellular component of innate immunity and contribute to the early host defence against HIV-1 infection, modulating the pathogenesis of acute HIV-1 infection (AHI). Emerging studies have identified tools for harnessing NK cell responses and expanding specialized NK subpopulations with adaptive/memory features, paving the way for development of novel HIV-1 therapeutics. This review highlights the knowns and unknowns regarding the role of NK cell subsets in the containment of acute HIV-1 infection, and summarizes recent advances in selectively augmenting NK cell functions through prophylactic and therapeutic interventions.

Improved induced innate immune response after cART initiation in people with HIV

Introduction

Impairment of the innate immune function may contribute to the increased risk of bacterial and viral infections in people with HIV (PWH). In this study we aimed to investigate the induced innate immune responses in PWH prior to and after initiation of combinational antiretroviral therapy (cART). Furthermore, we aimed to investigate if the induced innate immune responses before initiation of cART were associated with CD4+ T-cell recovery one year after initiating cART.

Material and method

The induced innate immune response was assessed by the TruCulture^® whole blood technique in 32 PWH before cART initiation and after 1, 6 and 12 months. To mimic bacterial and viral infections we used a panel of three stimuli (lipopolysaccharide (LPS), resiquimod (R848), and polyinosinic:polycytidylic acid (Poly I:C)) to stimulate the extracellular Toll-like receptor (TLR) 4 and the intracellular TLR7/8 and TLR3, respectively. The following cytokine responses were analyzed by Luminex 200: Tumor Necrosis Factor (TNF)-α, Interleukin (IL)-1b, IL-6, IL-8, IL-10, IL-12p40, IL17A, Interferon (IFN)-α, and IFN-γ.

Results

At baseline PWH with nadir CD4+ T-cell count <350 cell/µL had lower levels of LPS-, R848-, and Poly I:C-induced IL-6 and IFN-γ, LPS- and R848-induced TNF-α and IL-12, LPS induced IL-1b, and R848-induced IL-10 than PWH with nadir CD4+ T-cell count >350 cells/µL. The majority (>50%) had induced cytokine concentrations below the reference intervals at baseline which was most pronounced for the LPS- and Poly I:C-induced responses. The induced responses in the whole population improved after 12 months of cART, and more PWH had induced cytokine concentrations within the reference intervals after 12 months. However, the majority of PWH still had LPS-induced INF-α, INF-γ and Poly I:C-induced TNF-α and IL-6 below the reference interval. The induced innate immune responses before cART initiation were not associated with the CD4+ T-cell recovery after 12 months of cART.

Conclusion

The innate immune response was impaired in PWH, with a more pronounced impairment in PWH with low nadir CD4+ T-cell count. Initiation of cART improved the innate immune response, but compared to the reference intervals, some impairment remained in PWH without viral replication.

The HIV Latency Reversal Agent HODHBt Enhances NK Cell Effector and Memory-Like Functions by Increasing Interleukin-15-Mediated STAT Activation

Elimination of human immunodeficiency virus (HIV) reservoirs is a critical endpoint to eradicate HIV. One therapeutic intervention against latent HIV is "shock and kill." This strategy is based on the transcriptional activation of latent HIV with a latency-reversing agent (LRA) with the consequent killing of the reactivated cell by either the cytopathic effect of HIV or the immune system. We have previously found that the small molecule 3-hydroxy-1,2,3-benzotriazin-4(3H)-one (HODHBt) acts as an LRA by increasing signal transducer and activator of transcription (STAT) factor activation mediated by interleukin-15 (IL-15) in cells isolated from aviremic participants. The IL-15 superagonist N-803 is currently under clinical investigation to eliminate latent reservoirs. IL-15 and N-803 share similar mechanisms of action by promoting the activation of STATs and have shown some promise in preclinical models directed toward HIV eradication. In this work, we evaluated the ability of HODHBt to enhance IL-15 signaling in natural killer (NK) cells and the biological consequences associated with increased STAT activation in NK cell effector and memory-like functions. We showed that HODHBt increased IL-15-mediated STAT phosphorylation in NK cells, resulting in increases in the secretion of CXCL-10 and interferon gamma (IFN-γ) and the expression of cytotoxic proteins, including granzyme B, granzyme A, perforin, granulysin, FASL, and TRAIL. This increased cytotoxic profile results in increased cytotoxicity against HIV-infected cells and different tumor cell lines. HODHBt also improved the generation of cytokine-induced memory-like NK cells. Overall, our data demonstrate that enhancing the magnitude of IL-15 signaling with HODHBt favors NK cell cytotoxicity and memory-like generation, and thus, targeting this pathway could be further explored for HIV cure interventions. IMPORTANCE Several clinical trials targeting the HIV latent reservoir with LRAs have been completed. In spite of a lack of clinical benefit, they have been crucial to elucidate hurdles that "shock and kill" strategies have to overcome to promote an effective reduction of the latent reservoir to lead to a cure. These hurdles include low reactivation potential mediated by LRAs, the negative influence of some LRAs on the activity of natural killer and effector CD8 T cells, an increased resistance to apoptosis of latently infected cells, and an exhausted immune system due to chronic inflammation. To that end, finding therapeutic strategies that can overcome some of these challenges could improve the outcome of shock and kill strategies aimed at HIV eradication. Here, we show that the LRA HODHBt also improves IL-15-mediated NK cell effector and memory-like functions. As such, pharmacological enhancement of IL-15-mediated STAT activation can open new therapeutic avenues toward an HIV cure.

Carrier-free micellar CpG interacting with cell membrane for enhanced immunological treatment of HIV-1

Unmethylated CpG motifs activate toll-like receptor 9 (TLR9), leading to sequence- and species-specific immune stimulation. Here, we engineered a CpG oligodeoxyribonucleotide (ODN) with multiple hydrophobic moieties, so-called lipid-modified uracil, which resulted in a facile micelle formation of the stimulant. The self-assembled CpG nanostructure (U4CpG) containing the ODN 2216 sequence was characterized by various spectroscopic and microscopic methods together with molecular dynamics simulations. Next, we evaluated the nano-immunostimulant for enhancement of anti-HIV immunity. U4CpG treatment induced activation of plasmacytoid dendritic cells (pDCs) and natural killer (NK) cells in healthy human peripheral blood, which produced type I interferons (IFNs) and IFN-γ in human peripheral blood mononuclear cells (PBMCs). Moreover, we validated the activation and promotion efficacy of U4CpG in patient-derived blood cells, and HIV-1 spread was significantly suppressed by a low dosage of the immunostimulant. Furthermore, U4CpG-treated PBMC cultured medium elicited transcription of latent HIV-1 in U1 cells indicating that U4CpG reversed HIV-1 latency. Thus, the functions of U4CpG in eradicating HIV-1 by enhancing immunity and reversing latency make the material a potential candidate for clinical studies dealing with viral infection.

Exosomes in HIV infection

PURPOSE OF REVIEW

The exosomes play a critical role in HIV infection, which constitute a pathway to release intracellular material and exchange material and information between cells. Exosomes have become a hotspot in the field of AIDS research. This review introduces the formation process of HIV particles and exosomes, and summarizes the role of exosomes in the progression of HIV disease from multiple aspects.

RECENT FINDINGS

Many components of the exosomes involved in HIV transfer and replication affect the occurrence, development, and outcome of AIDS, and are closely related to HIV infection. Exosomes can have a dual impact on HIV infection, and play an important role in activating the latent reservoir of HIV and affecting the chronic inflammation of HIV. The biological information carried by exosomes is also of great significance for the prediction of HIV disease.

SUMMARY

The present review summarizes the role of exosomes in HIV disease progression in various aspects in order to further understand the underlying mechanism affecting the infection and providing a new idea for the clinical diagnosis and treatment of AIDS.

Tissue-specific transcriptional profiling of plasmacytoid dendritic cells reveals a hyperactivated state in chronic SIV infection

HIV associated immune activation (IA) is associated with increased morbidity in people living with HIV (PLWH) on antiretroviral therapy, and remains a barrier for strategies aimed at reducing the HIV reservoir. The underlying mechanisms of IA have not been definitively elucidated, however, persistent production of Type I IFNs and expression of ISGs is considered to be one of the primary factors. Plasmacytoid DCs (pDCs) are a major producer of Type I IFN during viral infections, and are highly immunomodulatory in acute HIV and SIV infection, however their role in chronic HIV/SIV infection has not been firmly established. Here, we performed a detailed transcriptomic characterization of pDCs in chronic SIV infection in rhesus macaques, and in sooty mangabeys, a natural host non-human primate (NHP) species that undergoes non-pathogenic SIV infection. We also investigated the immunostimulatory capacity of lymph node homing pDCs in chronic SIV infection by contrasting gene expression of pDCs isolated from lymph nodes with those from blood. We observed that pDCs in LNs, but not blood, produced high levels of IFNα transcripts, and upregulated gene expression programs consistent with T cell activation and exhaustion. We apply a novel strategy to catalogue uncharacterized surface molecules on pDCs, and identified the lymphoid exhaustion markers TIGIT and LAIR1 as highly expressed in SIV infection. pDCs from SIV-infected sooty mangabeys lacked the activation profile of ISG signatures observed in infected macaques. These data demonstrate that pDCs are a primary producer of Type I IFN in chronic SIV infection. Further, this study demonstrated that pDCs trafficking to LNs persist in a highly activated state well into chronic infection. Collectively, these data identify pDCs as a highly immunomodulatory cell population in chronic SIV infection, and a putative therapeutic target to reduce immune activation.

The abnormal distribution of NK cell subsets before HAART treatment may be related to the level of immune reconstitution in HIV patient

BACKGROUND

HIV infection leads to the damage of NK cells, which is closely associated with the disease's progression, but whether it affects immune reconstitution after Highly Active Antiretroviral Therapy (HAART) is not clear.

METHODS

From March 9 to October 31, 2017, a total of 75 confirmed cases with HIV in Wenzhou were collected and analyzed. NK cell subsets were measured and compared among three groups: the control group, the group whose CD4⁺ T cell counts <200/μL (named as low-CD4 group) and the group whose CD4⁺ T cell counts ≥200/μL (named as high-CD4 group). The lymphocytic subsets were dynamically monitored in patients with HIV after HAART.

RESULTS

Patients in low-CD4 group have lower proportion of CD3^-CD56^dimCD16⁺ NK cell subset, but have higher proportion of CD3^-CD56^-CD16⁺ NK cell subsets, which were compared with patients in high-CD4 group (All P values <0.01). There is a positive correlation between the proportion of CD3^-CD56^-CD16⁺ NK cell subset and CD4⁺ T cell counts (r = 0.628, p < 0.001). Patients in the low-CD4 group have higher expression of PD-1 and PS on NK cells than patients in the high-CD4 group (All P values < 0.05). The odds ratio of the proportion of the CD3^-CD56^-CD16⁺ NK cell subset before treatment for HAART efficacy was 0.826 (p < 0.001).

CONCLUSIONS

There are abnormalities in the proportion and function of NK cell subsets in HIV patients, which are associated with disease progression. The proportion of the CD3^-CD56^-CD16⁺ NK cell subset before treatment is related with HAART efficacy.

Antibody cooperative adsorption onto AuNPs and its exploitation to force natural killer cells to kill HIV-infected T cells

HIV represents a persistent infection which negatively alters the immune system. New tools to reinvigorate different immune cell populations to impact HIV are needed. Herein, a novel nanotool for the specific enhancement of the natural killer (NK) immune response towards HIV-infected T-cells has been developed. Bispecific Au nanoparticles (BiAb-AuNPs), dually conjugated with IgG anti-HIVgp120 and IgG anti-human CD16 antibodies, were generated by a new controlled, linker-free and cooperative conjugation method promoting the ordered distribution and segregation of antibodies in domains. The cooperatively-adsorbed antibodies fully retained the capabilities to recognize their cognate antigen and were able to significantly enhance cell-to-cell contact between HIV-expressing cells and NK cells. As a consequence, the BiAb-AuNPs triggered a potent cytotoxic response against HIV-infected cells in blood and human tonsil explants. Remarkably, the BiAb-AuNPs were able to significantly reduce latent HIV infection after viral reactivation in a primary cell model of HIV latency. This novel molecularly-targeted strategy using a bispecific nanotool to enhance the immune system represents a new approximation with potential applications beyond HIV.

Persons who inject drugs (PWID) retain functional NK cells, dendritic cell stimulation, and adaptive immune recall responses despite prolonged opioid use

Previous literature suggests that acute opioid use results in the functional impairment of the immune response, thereby decreasing resistance to viral infection. Here, we assessed if innate and adaptive immune responses are compromised ex vivo in persons who inject drugs (PWID) and whether long-term injection drug use may impact host susceptibility to in vitro HIV infection. We measured the frequency, activation state, and functional profile of NK cells, dendritic cells, and CD4+ and CD8+ T cells in low-risk PWID who do not share needles, high-risk needle-sharing PWID, and control donors who did not inject drugs. We also assessed plasma levels of inflammatory markers and CD4+ T cell susceptibility to HIV infection. We observed a significant increase in the amount of sCD14 (P = 0.0023, n = 16) and sCD163 (P = 0.0001, n = 16) in the plasma of PWID compared to controls. Evidence of constitutive activation was noted in PWID as compared to controls with increased CD69 expression in CD56dim NK cells (P = 0.0103, n = 26) and increased CD38 and HLA-DR expression in CD4+ T cells (P = 0.0355, n = 23). However, no innate or adaptive functional differences were detected between PWID and controls, including: NK cell direct or antibody-dependent cellular cytotoxicity poly-functional response, TLR-stimulated dendritic cell/NK crosstalk, CD8+ T cell response to Staphylococcal enterotoxin B or CMV/EBV/FLU peptides, or constitutive or anti-CD3/CD28-stimulated CD4+ T cell infectivity with CCR5-tropic or CXCR4-tropic HIV-1 isolates. Our data indicate that PWID who utilize opioids over as prolonged time frame can retain a functional ex vivo immune response without a measurable increase in CD4+ T cell infectivity suggesting that leukocytes from PWID are not intrinsically more susceptibility to infection with HIV than non-PWID controls.

Hepatitis C virus modulates IgG glycosylation in HIV co-infected antiretroviral therapy suppressed individuals

OBJECTIVE

Glycosylation plays a critical role in mediating several antibody (mainly immunoglobulin G; IgG) immunological functions, including antibody-dependent cell-mediated cytotoxicity (ADCC), and anti-inflammatory activities. We investigated whether IgG glycosylation and immune profile patterns are differentially modulated in mono and dual infection using samples from untreated hepatitis C virus (HCV)-infected individuals with and without co-infection with antiretroviral therapy (ART)-suppressed HIV.

DESIGN

IgG glycosylation, immune subsets, natural killer cell function, and liver enzymes were assessed in 14 HCV mono-infected and 27 ART-suppressed HIV/HCV co-infected participants naïve to HCV treatment. Historic IgG glycosylation data from 23 ART-suppressed chronically HIV-infected individuals were also used for comparisons.

METHODS

Plasma IgG glycosylation was assessed using capillary electrophoresis. Whole blood was used for immune subset characterization by flow cytometry. Peripheral blood mononuclear cells were used to measure constitutive and interferon-α-induced K562 target cell lysis. Statistical analysis was performed using R (3.5.0).

RESULTS

HIV/HCV had lower levels of pro-ADCC-associated nonfucosylated glycans when compared with HIV [e.g. di-sialylated A2 percentage (%): P = 0.04], and higher levels of T and myeloid cell activation/exhaustion when compared with HCV (e.g. CD3CD8CD38 %: P < 0.001). Finally, in HCV high levels of the anti-inflammatory galactosylated and sialylated glycans were associated with low plasma levels of aspartate aminotransferase (AST), low CD8 T-cell activation, and high CD8 T-cell exhaustion.

CONCLUSION

HCV modulates IgG glycosylation profile in HIV co-infected individuals on suppressive ART. These results could inform on the modulation of IgG glycans in other mono and dual infections.

New signatures of poor CD4 cell recovery after suppressive antiretroviral therapy in HIV-1-infected individuals: involvement of miR-192, IL-6, sCD14 and miR-144

Up to 40% of newly diagnosed cases of HIV-1 infection are late diagnoses, with a profound decrease in CD4 cell counts in many cases. One-third of these individuals do not achieve optimal CD4 cell recovery (OR) after suppressive antiretroviral treatment (ART). This retrospective/longitudinal study of poor recovery (PR) included 79 HIV-1-infected individuals with CD4 count <200 cells/mm³ (25 PR and 54 OR) before ART. After suppressive ART, 21 PR and 24 OR individuals were further analysed, including paired samples. Selected miRs and plasma inflammatory markers were determined to investigate their potential predictive/diagnostic value for poor recovery. miR-192, IL-6 and sCD14 were independently associated with CD4 recovery before ART (p = 0.031, p = 0.007, and p = 0.008, respectively). The combination of these three factors returned a good discrimination (predictive value for PR) value of 0.841 (AUC, p < 0.001). After suppressive ART, miR-144 was independently associated with CD4 recovery (p = 0.017), showing a moderate discrimination value of 0.730 (AUC, p = 0.008) for PR. Our study provides new evidence on the relationship between miRs and HIV-1 infection that could help improve the management of individuals at HIV-1 diagnosis. These miRs and cytokines signature sets provide novel tools to predict CD4 cell recovery and its progression after ART.

NK Response Correlates with HIV Decrease in Pegylated IFN-α2a-Treated Antiretroviral Therapy-Suppressed Subjects

We previously reported that pegylated IFN-α2a (Peg-IFN-α2a) added to antiretroviral therapy (ART)-suppressed, HIV-infected subjects resulted in plasma HIV control and integrated HIV DNA decrease. We now evaluated whether innate NK cell activity or PBMC transcriptional profiles were associated with decreases in HIV measures. Human peripheral blood was analyzed prior to Peg-IFN-α2a administration (ART, baseline), after 5 wk of ART+Peg-IFN-α2a, and after 12 wk of Peg-IFN-α2a monotherapy (primary endpoint). After 5 wk of ART+Peg-IFN-α2a, immune subset frequencies were preserved, and induction of IFN-stimulated genes was noted in all subjects except for a subset in which the lack of IFN-stimulated gene induction was associated with increased expression of microRNAs. Viral control during Peg-IFN-α2a monotherapy was associated with 1) higher levels of NK cell activity and IFN-γ-induced protein 10 (IP-10) on ART (preimmunotherapy) and 2) downmodulation of NK cell KIR2DL1 and KIR2DL2/DL3 expression, transcriptional enrichment of expression of genes associated with NK cells in HIV controller subjects, and higher ex vivo IFN-α-induced NK cytotoxicity after 5 wk of ART+Peg-IFN-α2a. Integrated HIV DNA decline after immunotherapy was also associated with gene expression patterns indicative of cell-mediated activation and NK cytotoxicity. Overall, an increase in innate activity and NK cell cytotoxicity were identified as correlates of Peg-IFN-α2a-mediated HIV control.

Activated dendritic cells and monocytes in HIV immunological nonresponders: HIV-induced interferon-inducible protein-10 correlates with low future CD4+ recovery

Supplemental Digital Content is available in the text

Objective:

To explore monocyte and dendritic cell immune responses, and their association with future CD4⁺ gain in treated HIV patients with suboptimal CD4⁺ recovery.

Design:

A cross-sectional study of HIV-infected, virally suppressed individuals on antiretroviral therapy for at least 24 months; 41 immunological nonresponders (INRs) (CD4⁺ cell count <400 cells/μl) and 26 immunological responders (CD4⁺ cell count >600 cells/μl). Ten HIV-infected antiretroviral therapy-naive and 10 HIV-negative healthy persons served as controls. CD4⁺ cell counts were registered after median 2.4 and 4.7 years.

Methods:

Monocyte, dendritic-cell and T-cell activation and regulatory T cells (Tregs) were analyzed by flow cytometry. In INR and immunological responder subgroups matched on age and nadir CD4⁺ cell count, upregulation of interferon-inducible protein-10 (IP-10) and indoleamine 2,3-dioxygenase in monocytes and dendritic cells and cytokines in cell supernatants were measured in vitro in peripheral blood mononuclear cells stimulated with aldrithiol-2-inactivated HIV-1.

Results:

The INR group displayed higher spontaneous activation of both monocytes (HLA-DR⁺) and myeloid and plasmacytoid dendritic cells (HLA-DR⁺, CD83⁺ and CD86⁺) compared with immunological responders, and this was associated with increased T-cell activation (CD38⁺HLA-DR⁺), an effector memory T-cell phenotype and activated Tregs. The IP-10 response in monocytes after in-vitro HIV stimulation was negatively associated with prospective CD4⁺ gain. IP-10, indoleamine 2,3-dioxygenase and cytokines levels were comparable between the groups, but inversely correlated with activated Tregs in INRs.

Conclusion:

HIV-infected individuals with suboptimal immune recovery demonstrated more activated monocytes and in particular dendritic cells, compared with patients with acceptable CD4⁺ gain. A high level of HIV-specific IP-10 expression in monocytes may be predictive of future CD4⁺ recovery.

Aberrant natural killer (NK) cell activation and dysfunction among ART-treated HIV-infected adults in an African cohort

BACKGROUND

We examined NK cell phenotypes and functions after seven years of ART and undetectable viral loads (<50 copies/ml) with restored CD4 T-cell counts (≥500 cells/μl) and age-matched healthy-HIV-uninfected individuals from the same community.

METHODS

Using flow-cytometry, NK cell phenotypes were described using lineage markers (CD56^+/-CD16^+/-). NK cell activation was determined by expression of activation receptors (NKG2D, NKp44 and NKp46) and activation marker CD69. NK cell function was determined by CD107a, granzyme-b, and IFN-gamma production.

RESULTS

CD56 dim and CD56 bright NK cells were lower among ART-treated-HIV-infected than among age-matched-HIV-negative individuals; p = 0.0016 and p = 0.05 respectively. Production of CD107a (P = 0.004) and Granzyme-B (P = 0.005) was lower among ART-treated-HIV-infected relative to the healthy-HIV-uninfected individuals. NKG2D and NKp46 were lower, while CD69 expression was higher among ART-treated-HIV-infected than healthy-HIV-uninfected individuals.

CONCLUSION

NK cell activation and dysfunction persisted despite seven years of suppressive ART with "normalization" of peripheral CD4 counts.

Incomplete functional T-cell reconstitution in immunological non-responders at one year after initiation of antiretroviral therapy possibly predisposes them to infectious diseases

BACKGROUND

Immunological non-responders (INR) represent a unique category of HIV-infected patients on antiretroviral therapy. These patients have suppressed viremia but a suboptimal increase in CD4 cell count, which might have opposing effects on functional immune reconstitution. Hence, the extent of immune reconstitution in INR patients was investigated in order to determine their susceptibility to opportunistic infections.

METHODS

Twenty-three INR patients (CD4 increase <50 cells/mm³, viral load <40 copies/ml), 40 age-, sex-, and baseline CD4 count-matched responders (CD4 increase >100 cells/mm³, viral load <40 copies/ml), and 18 treatment failures defined as per the national guidelines were enrolled at 1year of antiretroviral therapy. The following examinations were performed: haemogram, phenotypic characterization by flow cytometry, and assessment of functional immune status by ELISPOT and intracellular cytokine assays.

RESULTS

A higher percentage of INR patients had clinically symptomatic infections than the responders. CD8⁺ activation and innate immune parameters, including the absolute neutrophil count and natural killer (NK) cell frequency and functionality, were restored in the INR patients. They had significantly higher non-HIV antigen-specific T-cell responses and activated CD4⁺ cells, but significantly compromised T-cell functionality, as assessed after anti-CD3 stimulation, and lower CD31⁺ and CD62L⁺CD4⁺ cells.

CONCLUSIONS

INR patients showed lower thymic output, incomplete functional T-cell reconstitution, higher responses to HIV co-pathogens, and higher symptomatic events, indicating the need for close monitoring and intervention strategies to overcome their continuing immunocompromised status.

The involvement of plasmacytoid cells in HIV infection and pathogenesis

Plasmacytoid dendritic cells (pDCs) are a unique dendritic cell subset that are specialized in type I interferon (IFN) production. pDCs are key players in the antiviral immune response and serve as bridge between innate and adaptive immunity. Although pDCs do not represent the main reservoir of the Human Immunodeficiency Virus (HIV), they are a crucial subset in HIV infection as they influence viral transmission, target cell infection and antigen presentation. pDCs act as inflammatory and immunosuppressive cells, thus contributing to HIV disease progression. This review provides a state of art analysis of the interactions between HIV and pDCs and their potential roles in HIV transmission, chronic immune activation and immunosuppression. A thorough understanding of the roles of pDCs in HIV infection will help to improve therapeutic strategies to fight HIV infection, and will further increase our knowledge on this important immune cell subset.

Effects of HIV infection and ART on phenotype and function of circulating monocytes, natural killer, and innate lymphoid cells

HIV infection causes upregulation of markers of inflammation, immune activation and apoptosis of host adaptive, and innate immune cells particularly monocytes, natural killer (NK) and innate lymphoid cells (ILCs). Although antiretroviral therapy (ART) restores CD4 T-cell counts, the persistent aberrant activation of monocytes, NK and ILCs observed likely contributes to the incomplete recovery of T-cell effector functions. A better understanding of the effects of HIV infection and ART on the phenotype and function of circulating monocytes, NK, and ILCs is required to guide development of novel therapeutic interventions to optimize immune recovery.

Antifungal Activity of Plasmacytoid Dendritic Cells and the Impact of Chronic HIV Infection

Due to the effectiveness of combined antiretroviral therapy, people living with HIV can control viral replication and live longer lifespans than ever. However, HIV-positive individuals still face challenges to their health and well-being, including dysregulation of the immune system resulting from years of chronic immune activation, as well as opportunistic infections from pathogenic fungi. This review focuses on one of the key players in HIV immunology, the plasmacytoid dendritic cell (pDC), which links the innate and adaptive immune response and is notable for being the body’s most potent producer of type-I interferons (IFNs). During chronic HIV infection, the pDC compartment is greatly dysregulated, experiencing a substantial depletion in number and compromise in function. This immune dysregulation may leave patients further susceptible to opportunistic infections. This is especially important when considering a new role for pDCs currently emerging in the literature: in addition to their role in antiviral immunity, recent studies suggest that pDCs also play an important role in antifungal immunity. Supporting this new role, pDCs express C-type lectin receptors including dectin-1, dectin-2, dectin-3, and mannose receptor, and toll-like receptors-4 and -9 that are involved in recognition, signaling, and response to a wide variety of fungal pathogens, including Aspergillus fumigatus, Cryptococcus neoformans, Candida albicans, and Pneumocystis jirovecii. Accordingly, pDCs have been demonstrated to recognize and respond to certain pathogenic fungi, measured via activation, cytokine production, and fungistatic activity in vitro, while in vivo mouse models indicated a strikingly vital role for pDCs in survival against pulmonary Aspergillus challenge. Here, we discuss the role of the pDC compartment and the dysregulation it undergoes during chronic HIV infection, as well as what is known so far about the role and mechanisms of pDC antifungal activity.

Natural killer cells in HIV-1 infection and therapy

: Natural killer (NK) cells are important effectors of innate immunity playing a key role in the eradication and clearance of viral infections. Over the recent years, several studies have shown that HIV-1 pathologically changes NK cell homeostasis and hampers their antiviral effector functions. Moreover, high levels of chronic HIV-1 viremia markedly impair those NK cell regulatory features that normally regulate the cross talks between innate and adaptive immune responses. These pathogenic events take place early in the infection and are associated with a pathologic redistribution of NK cell subsets that includes the expansion of anergic CD56/CD16 NK cells with an aberrant repertoire of activating and inhibitory receptors. Nevertheless, the presence of specific haplotypes for NK cell receptors and the engagement of NK cell antibody-dependent cell cytotocity have been reported to control HIV-1 infection. This dichotomy can be extremely useful to both predict the clinical outcome of the infection and to develop alternative antiviral pharmacological approaches. Indeed, the administration of antiretroviral therapy in HIV-1-infected patients restores NK cell phenotype and functions to normal levels. Thus, antiretroviral therapy can help to develop NK cell-directed therapeutic strategies that include the use of broadly neutralizing antibodies and toll-like receptor agonists. The present review discusses how our current knowledge of NK cell pathophysiology in HIV-1 infection is being translated both in experimental and clinical trials aimed at controlling the infection and disease.

CD1d-Restricted Natural Killer T Cells Are Preserved in Indian Long-Term Nonprogressors

BACKGROUND

Natural killer T (NKT) cells act as a bridge between innate and adaptive immune responses. Limited information is available regarding the role of NKT cells in the HIV disease progression especially HIV-1 C infection.

METHODOLOGY

NKT cells were characterized for their frequency and the activation, aging, exhaustion status, and their proliferation ability in 32 long-term nonprogressors (LTNPs), 40 progressors, 18 patients before and after suppressive combination antiretroviral therapy (cART) along with 35 HIV-1-negative subjects using multicolor flow cytometry.

RESULTS

The frequencies of total NKT cells and their subpopulation were significantly higher in LTNPs as compared with those obtained in progressors (P < 0.0001) and were significantly associated with higher CD4 counts and with lower plasma viral loads. The percentage of activated, aged, and exhausted NKT cells were significantly lower in LTNPs as compared with the progressors and inversely correlated with CD4 count and positively with plasma viral loads. The NKT cells from the LTNPs showed higher proliferation ability. The frequency and proliferation ability of the NKT cells were partially restored after 12 months of suppressive cART but still lower than the levels in LTNPs. The degree of restoration after cART was similar in both CD4 and CD4 NKT cells.

CONCLUSION

The findings demonstrate significant association of preserved NKT cells with the nonprogressive HIV infection and also showed that exhausted NKT cells are associated with disease progression. Further characterization of their functionality and assessment of sustenance in HIV infection will help to understand the HIV pathogenesis and to develop immune therapies.

HCV viraemia associates with NK cell activation and dysfunction in antiretroviral therapy-treated HIV/HCV-co-infected subjects

The impact of hepatitis C virus (HCV) RNA levels on immune status in chronically HCV mono-infected when compared to HIV/HCV co-infected on antiretroviral therapy (ART) remains poorly understood. A total of 78 African American subjects HCV viraemic/naïve to HCV treatment (33 HCV genotype 1 mono-infected, 45 ART-treated HIV/HCV genotype 1 co-infected) were studied. Clinical and liver enzyme measurements were performed. Whole blood was analysed for immune subset changes by flow cytometry. Peripheral blood mononuclear cells (PBMC) were used for same-day constitutive and in vitro Interferon (IFN)-α-induced signal transducer and activator of transcription (STAT) phosphorylation, K562 target cell lysis and K562 target cell recognition-mediated IFN-γ production. Statistical analysis was performed using R (2.5.1) or JMP Pro 11. While both groups did not differ in the level of liver enzymes, HIV/HCV had higher T-cell activation/exhaustion, and constitutive STAT-1 phosphorylation compared to HCV. In contrast, CD4⁺ FoxP3⁺ CD25⁺ frequency, IFN-αR expression on NK cells, as well as constitutive and IFN-α-induced direct cytotoxicity were lower in HIV/HCV. Linear regression models further supported these results. Finally, increase in HCV viral load and CD4⁺ T-cell count had an opposite effect between the two groups on NK cell activity and T-cell activation, respectively. HCV viral load in ART-treated HIV/HCV co-infection was associated with greater immune activation/exhaustion and NK dysfunction than HCV viral load alone in HCV mono-infection. The more pronounced immune modulation noted in ART-treated HIV-co-infected/untreated HCV viraemic subjects may impact HCV disease progression and/or response to immunotherapy.

Gag-Specific CD4 T Cell Proliferation, Plasmacytoid Dendritic Cells, and Ethnicity in Perinatally HIV-1-Infected Youths: The ANRS-EP38-IMMIP Study

In perinatally HIV-1-infected youths living in France, we previously reported that Gag-specific CD4 and CD8 T cell proliferation is more frequently detected in patients of black ethnicity than in those of other ethnicities. We observed that black patients had higher levels of dendritic cells (DCs) than other patients. We aimed at studying the association of DC levels with Gag-specific T cell proliferation. The ANRS-EP38-IMMIP study is an observational study of youths aged between 15 and 24 years who were perinatally infected with HIV. A single blood sample was drawn for virological and immunological assays. Data from cART-treated 53 youths with undetectable plasma HIV RNA were analyzed. Gag-specific T cell proliferation was assessed by using a CFSE-based test. Peripheral blood myeloid dendritic cells (mDCs) and plasmacytoid dendritic cells (pDCs) were phenotyped by flow cytometry. Plasma markers were quantified by ELISA or multiplex assays. Logistic regression was used for univariate and multivariate analyses. Patients with Gag-specific CD4 T cell proliferative responses had significantly higher percentages and absolute counts of mDCs and pDCs in the peripheral blood than nonresponding patients. Gag-specific CD4 and CD8 T cell proliferation was associated with lower plasma sCD14 levels. Plasma levels of IFN-α, TRAIL, and chemokines involved in T cell migration to secondary lymphoid organs were not associated with T cell proliferation. Multivariate analysis confirmed the association between Gag-specific CD4 T cell proliferation and pDC levels. In conclusion, DC levels are a robust correlate of the presence of Gag-specific T cell proliferation in successfully treated youths.

Mechanisms by Which Interleukin-12 Corrects Defective NK Cell Anticryptococcal Activity in HIV-Infected Patients

Cryptococcus neoformans is a pathogenic yeast and a leading cause of life-threatening meningitis in AIDS patients. Natural killer (NK) cells are important immune effector cells that directly recognize and kill C. neoformans via a perforin-dependent cytotoxic mechanism. We previously showed that NK cells from HIV-infected patients have aberrant anticryptococcal killing and that interleukin-12 (IL-12) restores the activity at least partially through restoration of NKp30. However, the mechanisms causing this defect or how IL-12 restores the function was unknown. By examining the sequential steps in NK cell killing of Cryptococcus, we found that NK cells from HIV-infected patients had defective binding of NK cells to C. neoformans. Moreover, those NK cells that bound to C. neoformans failed to polarize perforin-containing granules to the microbial synapse compared to healthy controls, suggesting that binding was insufficient to restore a defect in perforin polarization. We also identified lower expression of intracellular perforin and defective perforin release from NK cells of HIV-infected patients in response to C. neoformans. Importantly, treatment of NK cells from HIV-infected patients with IL-12 reversed the multiple defects in binding, granule polarization, perforin content, and perforin release and restored anticryptococcal activity. Thus, there are multiple defects in the cytolytic machinery of NK cells from HIV-infected patients, which cumulatively result in defective NK cell anticryptococcal activity, and each of these defects can be reversed with IL-12.

The mechanisms by which NK cells bind directly to pathogens and deploy their deadly cytolytic machinery during microbial host defense are only beginning to be elucidated. With the goal of understanding this process, we used NK cells from HIV-infected patients, which were known to have a defect in killing of Cryptococcus neoformans. Taking advantage of previous studies that had shown that IL-12 restored killing, we used the cytokine as a gain-of-function approach to define the relevance of multiple steps in the recognition and cytolytic pathway. We demonstrated that NK cells from HIV-infected patients failed to kill Cryptococcus due to defects in perforin expression, granule polarization, and release of perforin. Additionally, IL-12 restored recognition of C. neoformans through binding of the NK-activating receptor NKp30. These observations identify important mechanisms used by NK cells to kill microbes and determine that defects in NK cells from HIV-infected patients are reversible.

Effect of chronic morphine administration on circulating dendritic cells in SIV-infected rhesus macaques

We studied the effect of chronic morphine administration on the circulating dendritic cell population dynamics associated with SIV infection using rhesus macaques. Animals were either first infected with SIV and then given chronic morphine, or visa versa. SIV infection increased the numbers of myeloid DCs (mDCs), but morphine treatment attenuated this mDC expansion. In contrast, morphine increased the numbers of plasmacytoid DCs (pDCs) in SIV-infected animals. Finally, chronic morphine administration (no SIV) transiently increased the numbers of circulating pDCs. These results show that chronic morphine induces a significant alteration in the available circulating levels of critical antigen-presenting cells.

Innate immune reconstitution with suppression of HIV-1

Progressive HIV-1 infection leads to both profound immune suppression and pathologic inflammation in the majority of infected individuals. While adaptive immune dysfunction, as evidenced by CD4⁺ T cell depletion and exhaustion, has been extensively studied, less is known about the functional capacity of innate immune cell populations in the context of HIV-1 infection. Given the broad susceptibility to opportunistic infections and the dysregulated inflammation observed in progressive disease, we hypothesized that there would be significant changes in the innate cellular responses. Using a cohort of patients with multiple samplings before and after antiretroviral therapy (ART) initiation, we demonstrated increased responses to innate immune stimuli following viral suppression, as measured by the production of inflammatory cytokines. Plasma viral load itself had the strongest association with this change in innate functional capacity. We further identified epigenetic modifications in the TNFA promoter locus in monocytes that are associated with viremia, suggesting a molecular mechanism for the observed changes in innate immune function following initiation of ART. These data indicate that suppression of HIV-1 viremia is associated with changes in innate cellular function that may in part determine the restoration of protective immune responses.

HIV mono-infection is associated with an impaired anti-hepatitis C virus activity of natural killer cells

OBJECTIVE

Hepatitis C virus (HCV) infection in HIV(+) patients is associated with faster liver disease progression compared with HCV mono-infection. HIV-associated immune defects are considered to play an important role in this context. Here, we analyzed the effects of HIV infection on natural killer (NK)-cell-mediated anti-HCV activity.

DESIGN

NK cell phenotype and interferon gamma (IFN-γ) production, NK cell-mediated inhibition of HCV replication and CD4 T-cell/NK cell interactions were studied in treatment naive HIV (n = 22), and HIV patients under combined antiretroviral therapy (n = 29), compared with healthy controls (n = 20).

METHODS

NK cell-mediated inhibition of HCV replication was analyzed using the HuH7A2HCVreplicon model. IFN-γ production of NK cells as well as interleukin-2 secretion of CD4 T lymphocytes were studied by flow cytometry.

RESULTS

Peripheral blood mononuclear cells from HIV(+) patients displayed a significantly impaired anti-HCV activity, irrespective of combined antiretroviral therapy. This could in part be explained by HIV-associated decline in NK cell numbers. In addition, NK cell IFN-γ production was significantly impaired in HIV infection. Accordingly, we found low frequency of IFN-γ(+) NK cells in HIV(+) patients to be associated with ineffective inhibition of HCV replication. Finally, we show that CD4 T-cell-mediated stimulation of NK cell IFN-γ production was dysregulated in HIV infection with an impaired interleukin-2 response of NK cells.

CONCLUSION

HIV infection has a strong suppressive effect on anti-HCV activity of NK cells. This may contribute to low spontaneous clearance rate and accelerated progression of HCV-associated liver disease observed in HIV(+) patients.

HIV-Specific Antibody-Dependent Cellular Cytotoxicity (ADCC) -Mediating Antibodies Decline while NK Cell Function Increases during Antiretroviral Therapy (ART)

Understanding alterations in HIV-specific immune responses during antiretroviral therapy (ART), such as antibody-dependent cellular cytotoxicity (ADCC), is important in the development of novel strategies to control HIV-1 infection. This study included 53 HIV-1 positive individuals. We evaluated the ability of effector cells and antibodies to mediate ADCC separately and in combination using the ADCC-PanToxiLux assay. The ability of the peripheral blood mononuclear cells (PBMCs) to mediate ADCC was significantly higher in individuals who had been treated with ART before seroconversion, compared to the individuals initiating ART at a low CD4⁺ T cell count (<350 cells/μl blood) and the ART-naïve individuals. The frequency of CD16 expressing natural killer (NK) cells correlated with both the duration of ART and Granzyme B (GzB) activity. In contrast, the plasma titer of antibodies mediating ADCC declined during ART. These findings suggest improved cytotoxic function of the NK cells if initiating ART early during infection, while the levels of ADCC mediating antibodies declined during ART.

Increased proportions of dendritic cells and recovery of IFNγ responses in HIV/HCV co-infected patients receiving ART

Dendritic cell (DC) numbers and functions can be affected by HIV and HCV disease, but the effects of antiretroviral therapy (ART) on DC and the implications of these changes are unclear. We examined circulating DC in samples from Indonesian patients beginning ART with advanced HIV disease and documented mild/moderate HCV hepatitis. Frequencies of myeloid and plasmacytoid DC increased after 6 months on ART, but frequencies of DC producing IL-12 or IFNα following stimulation with TLR agonists (CL075, CpG) did not change. IFNγ responses to CL075, HCV and other antigens rose over this period. Hence increased IFNγ responses during ART may be associated with increased DC frequencies rather than changes in their functional capacity.

Lysis of HIV-1-infected autologous CD4+ primary T cells by interferon-alpha-activated NK cells requires NKp46 and NKG2D

OBJECTIVE

Autologous HIV-1-infected CD4 primary T cells (aHIVCD4) have been shown to be largely resistant to natural killer (NK)-cell-mediated lysis because of viral strategies of immune evasion. We have previously shown that a preactivation of NK cells with plasmacytoid dendritic cells can significantly augment lysis of aHIVCD4 through a mechanism dependent on interferon-alpha (IFN-α).

DESIGN

The goal of the present study is to identify the specific NK-activating receptors involved in NK lysis of aHIVCD4 following IFN-α activation.

METHODS

Peripheral blood mononuclear cells (PBMC) were incubated with aHIVCD4 to induce the secretion of endogenous levels of IFN-α and drive NK activation. We then utilized a standard chromium lysis assay to assess the degree of IFN-α-activated lysis of aHIVCD4 in the presence or absence of masking antibodies to a panel of NK-activating receptors and co-receptors.

RESULTS

Direct recognition of HIV-1-infected, but not uninfected, autologous CD4 primary T cells by PBMC induced the secretion IFN-α (median 2280 pg/ml, P < 0.001, n = 9) that, in turn, activated NK cells (P < 0.001, n = 12) and significantly increased their cytolytic potential against aHIVCD4 (P < 0.01, n = 12). The masking of NKp46 (P < 0.01, n = 8) and NKG2D (P < 0.05, n = 8), but not 2B4, NTBA, NKp30 or NKp44, significantly reduced IFN-α-activated lysis of aHIVCD4.

CONCLUSIONS

Taken together, these results demonstrate that endogenous levels of IFN-α secreted by plasmacytoid dendritic cells induce NK cells to lyse aHIVCD4 via the engagement of NKp46 and NKG2D.

Persistence of pathological distribution of NK cells in HIV-infected patients with prolonged use of HAART and a sustained immune response

OBJECTIVE

A prospective analysis of the distribution of NK subsets and natural cytotoxicity receptors (NKp30/NKp46) in HIV patients with long-term HAART use and sustained virological and immunological response.

METHODS

The main inclusion criteria were: at least 3 years' receipt of HAART; current CD4+ count ≥ 500 cells/mm3; undetectable viral load for at least 24 months; no hepatotropic virus co-infection. Percentages of CD56dim, CD56bright NK cells and CD56neg CD16+ cells were obtained. Expression of the NCRs, NKp30 and NKp46 was analysed in CD56+ cells. Thirty-nine infected patients and sixteen healthy donors were included in the study.

RESULTS

The percentages of total CD56+ and CD56dim NK cells were significantly lower in HIV-infected patients than in healthy donors (70.4 vs. 50.3 and 80.9 vs. 66.1 respectively). The percentage of total CD56+ NK cells expressing NCR receptors was lower in HIV patients than in healthy donors (NKp30: 25.20 vs. 58.63; NKp46: 24.8 vs. 50.59). This was also observed for CD56dim and CD56bright NK cells. Length of time with undetectable HIV viral load was identified as an independent factor associated with higher expression of NKp30 and NKp46.

CONCLUSION

Despite the prolonged and effective use of HAART, HIV-infected patients do not fully reconstitute the distribution of NK cells. Length of time with an undetectable viral load was related to greater recovery of NKp30/NKp46 receptors.

HIV-specific ADCC improves after antiretroviral therapy and correlates with normalization of the NK cell phenotype

BACKGROUND

Natural killer (NK) cell phenotype and function have recently gained much attention as playing crucial roles in antibody-dependent cellular cytotoxicity (ADCC). We investigated NK cell function, as measured by ADCC, in HIV-1-positive individuals before and 6 months after highly active antiretroviral therapy (HAART) initiation.

METHOD

The ability of antibodies and NK cells to mediate ADCC was investigated separately and in combination in an autologous model. The NK cell subset distribution and NK cell phenotype (ie, expression of maturation and activation markers within NK cell subsets) were analyzed.

RESULTS

The ability of NK cells to mediate ADCC was significantly increased after only 6 months of HAART and was not explained by a normalization of NK cell subsets (CD56 CD16 and CD56 CD16 NK cells) but rather by normalization in the frequency of NK cells expressing CCR7 and CD27. For individuals with no increase in ADCC after 6 months of HAART, the frequency of NK cells expressing NKp46 was downregulated. The ability of antibodies to mediate ADCC alone and in combination in an autologous model was not improved.

CONCLUSIONS

HAART improves the ability of NK cells to mediate ADCC after 6 months. This improvement does not correlate with general immune restoration, as measured by CD4 T-cell counts, but rather to a decrease in the frequency of NK cells expressing CCR7 and CD27.

Ruxolitinib and tofacitinib are potent and selective inhibitors of HIV-1 replication and virus reactivation in vitro

The JAK-STAT pathway is activated in both macrophages and lymphocytes upon human immunodeficiency virus type 1 (HIV-1) infection and thus represents an attractive cellular target to achieve HIV suppression and reduced inflammation, which may impact virus sanctuaries. Ruxolitinib and tofacitinib are JAK1/2 inhibitors that are FDA approved for rheumatoid arthritis and myelofibrosis, respectively, but their therapeutic application for treatment of HIV infection was unexplored. Both drugs demonstrated submicromolar inhibition of infection with HIV-1, HIV-2, and a simian-human immunodeficiency virus, RT-SHIV, across primary human or rhesus macaque lymphocytes and macrophages, with no apparent significant cytotoxicity at 2 to 3 logs above the median effective antiviral concentration. Combination of tofacitinib and ruxolitinib increased the efficacy by 53- to 161-fold versus that observed for monotherapy, respectively, and each drug applied alone to primary human lymphocytes displayed similar efficacy against HIV-1 containing various polymerase substitutions. Both drugs inhibited virus replication in lymphocytes stimulated with phytohemagglutinin (PHA) plus interleukin-2 (IL-2), but not PHA alone, and inhibited reactivation of latent HIV-1 at low-micromolar concentrations across the J-Lat T cell latency model and in primary human central memory lymphocytes. Thus, targeted inhibition of JAK provided a selective, potent, and novel mechanism to inhibit HIV-1 replication in lymphocytes and macrophages, replication of drug-resistant HIV-1, and reactivation of latent HIV-1 and has the potential to reset the immunologic milieu in HIV-infected individuals.

Evaluation of Langerhans cells counts comparing HIV-positive and negative anal squamous cell-carcinoma patients

PURPOSE

To investigate the differences in Langerhans cells (LCs) populations between HIV-positive and negative anal squamous cell carcinomas patients.

METHODS

Twenty five patients (14 HIV-positive and 11 HIV-negative) were evaluated. Paraffin-block transversal thin sections from biopsies of anal squamous cell carcinomas (ASCC) were stained using the anti-CD1A antibody that identifies activated LCs. LCs counts were performed using histometry at 20 different sites, at baseline in the ASCC cases. These were then compared with LCs counts in anal canal specimens from HIV-negative and positive patients without ASCC (controls groups).

RESULTS

In patients with ASCC, the LC count was greater among HIV-negative individuals than among HIV-positive individuals (p<0.05). The LC count was greater in the control HIV-negative group than in HIV-positive patients with ASCC (p<0.05).

CONCLUSION

There was a lower amount of activated LCs in HIV-positive patients with anal squamous cell carcinomas than in HIV-negative patients, thereby suggesting worsening of the immune response.

Short-term HIV-1 treatment interruption is associated with dysregulated TLR-stimuli responsiveness

Viremia during human immunodeficiency virus type-1 (HIV-1) infection results in progressive impairment of several components of the immune system. Here a unique model of repeated treatment interruptions (TIs) was used with the aim to reveal the effect of controlled short-term viremia on innate stimuli responsiveness and circulating dendritic cells (DCs). Sequential peripheral blood samples from HIV-1-infected patients on combination antiretroviral therapy, subjected to repeated TI cycles as part of a therapeutic DNA vaccination study, were analyzed. In vitro responsiveness of peripheral blood mononuclear cells to toll-like receptor (TLR) stimuli was analyzed by cytokine secretion, and frequencies of plasmacytoid DCs (pDCs) and myeloid DCs (mDCs) were monitored by flow cytometry. These parameters were found not to be significantly different between the vaccinated and placebo groups. Instead, independent of vaccination altered in vitro TLR responsiveness was observed in parallel with TI cycles. TLR7/8-triggered secretion of IL-12 and IFN-α, as well as TLR9-triggered secretion of IL-12, was hyperactivated. In contrast, expression of IFN-α after TLR9 stimulation decreased during the initial cycle of TI. Reduced frequencies of pDCs and mDCs, compared with baseline, were noted before and during the second TI, respectively. Furthermore, spontaneous ex vivo release of IL-12 from PBMC was noted during cycles of TI. In conclusion, these results suggest that consequences of short-term TI include dysregulated TLR responses and fluctuations in the frequencies of circulating DCs. Knowledge of these immunological factors may influence the continuation of stringent treatment schedules during HIV infections.

Increased activity of extrinsic and intrinsic apoptosis pathways in different mononuclear cell types in HIV type 1-infected patients regardless of whether they are depleted in disease

Myeloid dendritic cells (mDCs) are essential for initiation of adaptive immune responses but are depleted in HIV infection. Evidence suggests that apoptosis mediates loss, and to further understand the pathways involved, expression of caspases mediating apoptosis via the extrinsic and intrinsic pathways was analyzed. Blood samples were obtained from 14 HIV-infected patients (nine HAART and five antiretroviral naive) and 10 healthy controls. The expression of intracellular active caspases 8 and 9, associated with extrinsic and intrinsic pathways of apoptosis, and the expression of cell membrane death receptors and their ligands were assessed by flow cytometry in mDC. Additionally, expression of active caspases 8 and 9 in purified mDCs cultured for 5 days with HIV-Bal was analyzed. Frequencies of mDCs in the blood of HIV-infected patients were decreased while expression of CCR7 was up-regulated. Up to 94.4% and 91.8% of mDCs from HIV-infected patients expressed active caspases 8 and 9, respectively, compared to 24.5% and 19.9% from healthy controls (both p<0.0001). However, monocytes and B and T cells from HIV-infected patients also showed increased levels of these caspases. Percentages of FASL expression in mDCs were also elevated in HIV-infected individuals while mDCs expressing cell membrane death receptors remained unchanged. No differences between HAART and naive patients were observed for any of the molecules measured. Caspases 8 and 9 were up-regulated in mDCs cocultured with HIV despite lack of productive infection in vitro. Extrinsic and intrinsic pathways of apoptosis are up-regulated in HIV infection but do not correlate with cell depletion.

Dysregulated immunophenotypic attributes of plasmacytoid but not myeloid dendritic cells in HIV-1 infected individuals in the absence of highly active anti-retroviral therapy

Dendritic cells (DC) in HIV-1-infected individuals are decreased and their dysfunction has been implicated in HIV-1 immunopathogenesis. The mechanism of their dysfunction remains unclear, thus we analysed the expression of membrane molecules associated with immune regulation and DC activation in myeloid (mDC) and plasmacytoid DC (pDC) in therapy-naive and highly active anti-retroviral therapy (HAART)-treated HIV-1(+) patients. DC from healthy controls, untreated HIV-1(+) and HAART-treated patients were assessed by flow cytometry for expression of: anergy and apoptosis inducing molecules [programmed death (PD)-1 and its ligands PD-L1 and PD-L2], inhibitory and regulatory T cell-inducing molecules [immunoglobulin-like transcript (ILT)-3 and ILT-4], interferon (IFN)-α inhibitory receptor (ILT-7) and co-stimulatory molecules (CD80, CD83, and CD86). pDC from untreated HIV-1(+) patients expressed significantly lower levels of ILT-7 compared to healthy controls, while HAART-treated patients showed normal expression. pDC were also found to express moderately higher levels of PD-L1 and ILT-3 and lower levels of PD-L2 receptors in untreated patients compared to controls and HAART-treated patients. No significant changes were observed in mDC. There were no associations between the percentages and levels of expression of these molecules by pDC and viral load or CD4 T cell count. In conclusion, pDC but not mDC from HIV-1(+) patients with active viraemia display higher levels of apoptosis and T regulatory-inducing molecules and may be predisposed to chronically produce IFN-α through down-regulation of ILT-7. HAART restored normal expression levels of these receptors.

Dendritic Cells in HIV-1 and HCV Infection: Can They Help Win the Battle?

Persistent infections with human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) are a major cause of morbidity and mortality worldwide. As sentinels of our immune system, dendritic cells (DCs) play a central role in initiating and regulating a potent antiviral immune response. Recent advances in our understanding of the role of DCs during HIV-1 and HCV infection have provided crucial insights into the mechanisms employed by these viruses to impair DC functions in order to evade an effective immune response against them. Modulation of the immunological synapse between DC and T-cell, as well as dysregulation of the crosstalk between DCs and natural killer (NK) cells, are emerging as two crucial mechanisms. This review focuses on understanding the interaction of HIV-1 and HCV with DCs not only to understand the immunopathogenesis of chronic HIV-1 and HCV infection, but also to explore the possibilities of DC-based immunotherapeutic approaches against them. Host genetic makeup is known to play major roles in infection outcome and rate of disease progression, as well as response to anti-viral therapy in both HIV-1 and HCV-infected individuals. Therefore, we highlight the genetic variations that can potentially affect DC functions, especially in the setting of chronic viral infection. Altogether, we address if DCs’ potential as critical effectors of antiviral immune response could indeed be utilized to combat chronic infection with HIV-1 and HCV.

Human endogenous retrovirus expression is inversely associated with chronic immune activation in HIV-1 infection

Human endogenous retroviruses (HERV) are remnants of ancestral retroviral infections integrated into the germ line, and constitute approximately 8% of the genome. Several autoimmune disorders, malignancies, and infectious diseases such as HIV-1 are associated with higher HERV expression. The degree to which HERV expression in vivo results in persistent inflammation is not known. We studied the association of immune activation and HERV-K expression in 20 subjects with chronic, untreated progressive HIV-1 infection and 10 HIV-1 negative controls. The mean HERV-K gag and env RNA expression level in the HIV-1 infected cohort was higher than in the control group (p = 0.0003), and was negatively correlated with the frequency of activated CD38+HLA-DR+CD4+ T cells (Rho = -0.61; p = 0.01) and activated CD38+HLA-DR+CD8+ T cells (Rho = -0.51; p = 0.03). Although HIV-infected persons had higher levels of HERV-K RNA expression (as expected), the level of RNA expression was negatively associated with level of T cell activation. The mechanism for this unexpected association remains to be defined.

Pathogenesis of the immune reconstitution inflammatory syndrome in HIV-infected patients

PURPOSE OF REVIEW

The immune reconstitution inflammatory syndrome (IRIS) is an important clinical complication in HIV-infected patients initiating antiretroviral therapy. This review focuses on the latest literature pertaining to the pathogenesis of IRIS.

RECENT FINDINGS

The clinical manifestations of IRIS are heterogeneous due to the variety of opportunistic infections that are associated with this inflammatory syndrome. However, the disproportionate inflammation is a defining hallmark for which common mechanisms are suspected. Lymphopenia-induced proliferation in the context of systemic immune activation, presence of high antigenic exposure and a wider availability of interleukin-7 contribute to the exacerbated immune response underlying IRIS. Defect in pathogen clearance by phagocytes might favor high pathogen burden, which in turn is thought to activate both innate immune cells and pathogen-specific T cells upon correction of the CD4 T-cell lymphopenia, predisposing to IRIS. This common scenario might be further invigorated by functional impairments among regulatory T cells.

SUMMARY

Further insight into the cellular mechanisms driving IRIS is urgently needed. Understanding the relative contribution of distinct effector and regulatory T-cell subsets, and innate immune components to IRIS is required to inspire future therapeutic approaches.

Antiretroviral therapy in Indian setting: when & what to start with, when & what to switch to?

With the rapid scale up of antiretroviral therapy, there is a dramatic decline in HIV related morbidity and mortality in both developed and developing countries. Several new safe antiretroviral, and newer class of drugs and monitoring assays are developed recently. As a result the treatment guideline for the management of HIV disease continue to change. This review focuses on evolving science on Indian policy - antiretroviral therapy initiation, which drugs to start with, when to change the initial regimen and what to change.

Longitudinal changes of peripheral blood DC subsets and regulatory T cells in Chinese chronic HIV-1-infected patients during antiretroviral therapy

It has been emphasized that chronic generalized immune dysfunction is the leading event in the pathogenesis of HIV infection, in which the contribution of dendritic cells (DCs) and regulatory T cells (Tregs) should not be underestimated. In current study, we assessed the longitudinal changes of peripheral blood DC subsets and Tregs in chronically asymptomatic treatment-naive HIV-1-infected patients during 60 weeks of antiretroviral therapy (ART), and compared with those in healthy controls and long term non-progressors (LTNPs). Blood samples were collected at week 0, 4, 12, 24, 48 and 60 of treatment to measure the counts of DC subsets and Tregs by flow cytometry and IFN-a plasma levels by ELISA. The counts of myeloid dendritic cells (mDCs) increased during ART, reaching similar levels to healthy controls at week 60 post ART but still lower than those of LTNPs. In HIV-1-infected patients, the mDCs counts were directly correlated with CD4 counts during ART. Changes in mDCs at week 8 were positively correlated with the changes in CD4 counts at week 60 post ART. However, the counts and function of plasmacytoid dendritic cells (pDCs) remained relatively stable during ART, and similar to those in healthy controls and LTNPs. The percentage of Tregs increased before ART and normalized after ART. Importantly, we found pDCs counts were associated with percentage of Tregs during ART, which may help in understanding of the role of these cells in HIV infection.

HIV RNA suppression and immune restoration: can we do better?

HAART has significantly changed the natural history of HIV infection: patients receiving antiretrovirals are usually able to control viremia, even though not all virological responders adequately recover their CD4+ count. The reasons for poor immune restoration are only partially known and they include genetic, demographic and immunologic factors. A crucial element affecting immune recovery is immune activation, related to residual viremia; indeed, a suboptimal virological control (i.e., low levels of plasma HIV RNA) has been related with higher levels of chronic inflammation and all-cause mortality. The sources of residual viremia are not yet completely known, even though the most important one is represented by latently infected cells. Several methods, including 2-LTR HIV DNA and unspliced HIV RNA measurement, have been developed to estimate residual viremia and predict the outcome of antiretroviral therapy. Considering that poor immunologic responders are exposed to a higher risk of both AIDS-related and non-AIDS-related diseases, there is a need of new therapeutic strategies, including immunomodulators and drugs targeting the latent viral reservoirs, in order to face residual viremia but also to “drive” the host immunologic responses.

Natural killer cell activation distinguishes Mycobacterium tuberculosis-mediated immune reconstitution syndrome from chronic HIV and HIV/MTB coinfection

BACKGROUND

With increased access to antiretroviral treatment (ART), immune reconstitution inflammatory syndrome (IRIS) in Mycobacterium tuberculosis (MTB)-infected populations remains a clinical challenge. We studied a cross-sectional cohort of HIV-infected subjects in Johannesburg (South Africa) to help define the immune correlates that best distinguish IRIS from ongoing MTB cases.

METHODS

We studied HIV+ subjects developing MTB-related unmasking tuberculosis-related immune reconstitution inflammatory syndrome (uTB-IRIS) after ART initiation; control groups were subjects with HIV and HIV/tuberculosis-coinfected subjects with comparable ART treatment. Testing was conducted with whole blood-based 4-color flow cytometry and plasma-based Luminex cytokine assessment.

RESULTS

Natural killer cell activation, C-reactive protein, and interleukin 8 serum concentration were significantly higher in uTB-IRIS subjects compared with both control groups. In addition, all MTB-coinfected subjects, independent of clinical presentation, had higher neutrophils and T-cell activation, together with lower lymphocytes, CD4⁺ T-cell, and myeloid dendritic cell counts. Using conditional inference tree analysis, we show that elevated natural killer cell activation in combination with lymphocyte count characterizes the immunological profile of uTB-IRIS.

CONCLUSION

Our results support a role for innate immune effectors in the immunopathogenesis of unmasking MTB-related IRIS and identify new immune parameters defining this pathology.

HIV-1 infection and induction of interferon alpha in plasmacytoid dendritic cells

PURPOSE OF REVIEW

Loss of blood plasmacytoid dendritic cell (pDC) in HIV-1 infection is thought to impact on adaptive immune responses whilst the virus also induces aberrant interferon alpha (IFN-α) production that may fuel chronic immune activation and drive disease progression. Recent attention has focussed on the pathway of HIV-induced IFN-α production by pDC and the new data are reviewed here together with the pathway leading to infection.

RECENT FINDINGS

Attachment to CD4 and chemokine co-receptors is essential for HIV-1 infection. Although CD4, but not co-receptor binding, is a major route for passage to endosomes and triggering of IFN-α secretion this may also occur by CD4-independent mechanisms involving other receptors. In contrast to other Toll-like receptor (TLR)-7 ligands and RNA viruses that stimulate pDC to secrete IFN-α for 2-3  h, HIV-1-stimulated pDC can give sustained IFN-α production for up to 48  h which may contribute to chronic immune activation. This may reflect retention of HIV in early endosomes which also seems to be associated with incomplete maturation induced by HIV.

SUMMARY

HIV-1-pDC interactions contribute to pathogenesis through depletion and aberrant IFN-α production. New data on the pathway of pDC HIV-stimulated IFN-α secretion may facilitate therapy to reduce chronic immune activation and slow disease progression.

Biomarkers of immune dysfunction following combination antiretroviral therapy for HIV infection

Combination antiretroviral therapy (cART) has significantly reduced morbidity and mortality of HIV-infected patients, yet their life expectancy remains reduced compared with the general population. Most HIV-infected patients receiving cART have some persistent immune dysfunction characterized by chronic immune activation and premature aging of the immune system. Here we review biomarkers of T-cell activation (CD69, -25 and -38, HLA-DR, and soluble CD26 and -30); generalized immune activation (C-reactive protein, IL-6 and D-dimer); microbial translocation (lipopolysaccharide, 16S rDNA, lipopolysaccharide-binding protein and soluble CD14); and immune dysfunction of specific cellular subsets (T cells, natural killer cells and monocytes) in HIV-infected patients on cART and their relationship to adverse clinical outcomes including impaired CD4 T-cell recovery, as well as non-AIDS clinical events, such as cardiovascular disease.

Metabolic and anthropometric parameters contribute to ART-mediated CD4+ T cell recovery in HIV-1-infected individuals: an observational study

BACKGROUND

The degree of immune reconstitution achieved in response to suppressive ART is associated with baseline individual characteristics, such as pre-treatment CD4 count, levels of viral replication, cellular activation, choice of treatment regimen and gender. However, the combined effect of these variables on long-term CD4 recovery remains elusive, and no single variable predicts treatment response. We sought to determine if adiposity and molecules associated with lipid metabolism may affect the response to ART and the degree of subsequent immune reconstitution, and to assess their ability to predict CD4 recovery.

METHODS

We studied a cohort of 69 (48 females and 21 males) HIV-infected, treatment-naïve South African subjects initiating antiretroviral treatment (d4T, 3Tc and lopinavir/ritonavir). We collected information at baseline and six months after viral suppression, assessing anthropometric parameters, dual energy X-ray absorptiometry and magnetic resonance imaging scans, serum-based clinical laboratory tests and whole blood-based flow cytometry, and determined their role in predicting the increase in CD4 count in response to ART.

RESULTS

We present evidence that baseline CD4+ T cell count, viral load, CD8+ T cell activation (CD95 expression) and metabolic and anthropometric parameters linked to adiposity (LDL/HDL cholesterol ratio and waist/hip ratio) significantly contribute to variability in the extent of CD4 reconstitution (ΔCD4) after six months of continuous ART.

CONCLUSIONS

Our final model accounts for 44% of the variability in CD4+ T cell recovery in virally suppressed individuals, representing a workable predictive model of immune reconstitution.

Immune reconstitution under antiretroviral therapy: the new challenge in HIV-1 infection

Although highly active antiretroviral therapy has enabled constant progress in reducing HIV-1 replication, in some patients who are "aviremic" during treatment, the problem of insufficient immune restoration remains, and this exposes them to the risk of immune deficiency-associated pathologies. Various mechanisms may combine and account for this impaired immunologic response to treatment. A first possible mechanism is immune activation, which may be because of residual HIV production, microbial translocation, co-infections, immunosenescence, or lymphopenia per se. A second mechanism is ongoing HIV replication. Finally, deficient thymus output, sex, and genetic polymorphism influencing apoptosis may impair immune reconstitution. In this review we will discuss the tools at our disposal to identify the various mechanisms at work in a given patient and the specific therapeutic strategies we could propose based on this etiologic diagnosis.

Robust interferon-α and IL-12 responses by dendritic cells are related to efficient CD4+ T-cell recovery in HIV patients on ART

Amongst HIV patients with successful virological responses to antiretroviral therapy (ART), poor CD4(+) T-cell recovery is associated with low nadir CD4(+) T-cell counts and persistent immune activation. These factors might be influenced by dendritic cell (DC) function. Interferon-α-producing plasmacytoid DC and IL-12-producing myeloid DC were quantified by flow cytometry after stimulation with agonists to TLR7/8 (CL075) or TLR9 (CpG-ODN). These were compared between patients who achieved CD4(+) T-cell counts above or below 200 cells/μL after 6 months on ART (High vs. Low groups). High Group patients had more DC producing interferon-α or IL-12 at Weeks 6 and 12 on ART than Low Group patients. The frequencies of cytokine-producing DC at Week 12 were directly correlated with CD4(+) T-cell counts at baseline and at Week 12. Patients with good recovery of CD4(+) T-cells had robust TLR-mediated interferon-α responses by plasmacytoid DC and IL-12 responses by myeloid DC during early ART (1-3 months).