Dynamics of adaptive and innate immunity in patients treated during primary human immunodeficiency virus infection: results from Maraviroc in HIV Acute Infection (MAIN) randomized clinical trial

Plasma Cytokine Expression and Immune Reconstitution in Early and Delayed Anti-HIV 96-Weeks Treatment: A Retrospective Study

HIV is an immunodeficiency disease with emergence of inadequate corresponding reconstruction therapies. Pyroptosis of CD4+T cell is mainly caused by immune activation and inflammation that cannot be reduced by successful antiretroviral therapy (ART) alone. Coinfections because of CD4+T cell reconstitution failure can occur. Anti-inflammatory treatment determines the success of immune reconstitution. In our experiment, only a few cytokines could recover to normal level following a 2-year antiretroviral treatment in early ART initiation, which is consistent with current findings about adjuvant HIV anti-inflammatory therapy. Early infection is often accompanied by a more severe inflammatory response. Innate immunity cytokines like granulocyte macrophage-colony stimulating factor, IFN-γ induced protein 10 kDa, and tumor necrosis factor-α exhibited the most elevated levels among all kinds of inflammatory cytokines. The correlation analysis showed at least eight cytokines contributing to the changes of CD4/CD8 ratio.

Natural killer cells and their exosomes in viral infections and related therapeutic approaches: where are we?

Innate immunity is the first line of the host immune system to fight against infections. Natural killer cells are the innate immunity lymphocytes responsible for fighting against virus-infected and cancerous cells. They have various mechanisms to suppress viral infections. On the other hand, viruses have evolved to utilize different ways to evade NK cell-mediated responses. Viruses can balance the response by regulating the cytokine release pattern and changing the proportion of activating and inhibitory receptors on the surface of NK cells. Exosomes are a subtype of extracellular vesicles that are involved in intercellular communication. Most cell populations can release these nano-sized vesicles, and it was shown that these vesicles produce identical outcomes to the originating cell from which they are released. In recent years, the role of NK cell-derived exosomes in various diseases including viral infections has been highlighted, drawing attention to utilizing the therapeutic potential of these nanoparticles. In this article, the role of NK cells in various viral infections and the mechanisms used by viruses to evade these important immune system cells are initially examined. Subsequently, the role of NK cell exosomes in controlling various viral infections is discussed. Finally, the current position of these cells in the treatment of viral infections and the therapeutic potential of their exosomes are reviewed. Video Abstract.

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.

Natural killer cells in antiviral immunity

Natural killer (NK) cells play an important role in innate immune responses to viral infections. Here, we review recent insights into the role of NK cells in viral infections, with particular emphasis on human studies. We first discuss NK cells in the context of acute viral infections, with flavivirus and influenza virus infections as examples. Questions related to activation of NK cells, homing to infected tissues and the role of tissue-resident NK cells in acute viral infections are also addressed. Next, we discuss NK cells in the context of chronic viral infections with hepatitis C virus and HIV-1. Also covered is the role of adaptive-like NK cell expansions as well as the appearance of CD56- NK cells in the course of chronic infection. Specific emphasis is then placed in viral infections in patients with primary immunodeficiencies affecting NK cells. Not least, studies in this area have revealed an important role for NK cells in controlling several herpesvirus infections. Finally, we address new data with respect to the activation of NK cells and NK cell function in humans infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) giving rise to coronavirus disease 2019 (COVID-19).

Maraviroc as a potential HIV-1 latency-reversing agent in cell line models and ex vivo CD4 T cells

Recent studies have suggested that the CCR5 antagonist maraviroc (MVC) may exert an HIV-1 latency reversal effect. This study aimed at defining MVC-mediated induction of HIV-1 in three cell line latency models and in ex vivo CD4 T cells from six patients with suppressed viraemia. HIV-1 induction was evaluated in TZM-bl cells by measuring HIV-1 LTR-driven luciferase expression, and in ACH-2 and U1 latently infected cell lines by measuring cell-free (CFR) and cell-associated (CAR) HIV-1 RNA by qPCR. NF-κB p65 was quantified in nuclear extracts by immunodetection. In ex vivo CD4 T cells, CAR, CFR and cell-associated DNA (CAD) were quantified at baseline and 1-7-14 days post-induction (T1, T7, T14). At T7 and T14, the infectivity of the CD4 T cells co-cultured with MOLT-4/CCR5 target cells was evaluated in the TZM-bl assay (TZA). Results were expressed as fold activation (FA) with respect to untreated cells. No LTR activation was observed in TZM-bl cells at any MVC concentration. NF-κB activation was only modestly upregulated (1.6±0.4) in TZM-bl cells with 5 µM MVC. Significant FA of HIV-1 expression was only detected at 80 µM MVC, namely on HIV-1 CFR in U1 (3.1±0.9; P=0.034) and ACH-2 cells (3.9±1.4; P=0.037). CFR was only weakly stimulated at 20 µM in ACH-2 (1.7±1.0 FA) cells and at 5 µM in U1 cells (1.9±0.5 FA). Although no consistent pattern of MVC-mediated activation was observed in ex vivo experiments, substantial FA values were detected sparsely on individual samples with different parameters. Notably, in one sample, MVC stimulated all parameters at T7 (2.3±0.2 CAD, 6.8±3.7 CAR, 18.7±16.7 CFR, 7.3±0.2 TZA). In conclusion, MVC variably induces HIV-1 production in some cell line models not previously used to test its latency reversal potential. In ex vivo CD4 T cells, MVC may exert patient-specific HIV-1 induction; however, clinically relevant patterns, if any, remain to be defined.

Enhanced Immunological Recovery With Early Start of Antiretroviral Therapy During Acute or Early HIV Infection-Results of Italian Network of ACuTe HIV InfectiON (INACTION) Retrospective Study

BACKGROUND

Viral load peak and immune activation occur shortly after exposure during acute or early HIV infection (AEHI). We aimed to define the benefit of early start of antiretroviral treatment (ART) during AEHI in terms of immunological recovery, virological suppression, and treatment discontinuation.

SETTING

Patients diagnosed with AEHI (Fiebig stages I-V) during 2008-2014 from an analysis of 20 Italian centers.

METHODS

This was an observational, retrospective, and multicenter study. We investigated the effect of early ART (defined as initiation within 3 months from AEHI diagnosis) on time to virological suppression, optimal immunological recovery (defined as CD4 count ≥500/µL, CD4 ≥30%, and CD4/CD8 ≥1), and first-line ART regimen discontinuation by Cox regression analysis.

RESULTS

There were 321 patients with AEHI included in the study (82.9% in Fiebig stage III-V). At diagnosis, the median viral load was 5.67 log10 copies/mL and the median CD4 count was 456 cells/µL. Overall, 70.6% of patients started early ART (median time from HIV diagnosis to ART initiation 12 days, IQR 6-27). Higher baseline viral load and AEHI diagnosis during 2012-2014 were independently associated with early ART. HBV co-infection, baseline CD4/CD8 ≥1, lower baseline HIV-RNA, and AEHI diagnosis in recent years (2012-2014) were independently associated with a shorter time to virological suppression. Early ART emerged as an independent predictor of optimal immunological recovery after adjustment for baseline CD4 (absolute and percentage count) and CD4/CD8 ratio. The only independent predictor of first-line ART discontinuation was an initial ART regimen including > 3 drugs.

CONCLUSIONS

In a large cohort of well-characterized patients with AEHI, we confirmed the beneficial role of early ART on CD4+ T-cell recovery and on rates of CD4/CD8 ratio normalization. Moreover, we recognized baseline CD4/CD8 ratio as an independent factor influencing time to virological response in the setting of AEHI, thus giving new insights into research of immunological markers associated with virological control.

The Role of Natural Killer Cells and Regulatory T Cells While Aging with Human Immunodeficiency Virus

Combined antiretroviral therapy (cART) has increased the quality of life of people living with HIV (PLHIV). Consequently, the number of PLHIV >50 years is increasing worldwide. Patients on cART are known to remain in a proinflammatory state. The latter is linked to the development of non-AIDS-related chronic conditions. Although the number of aging PLHIV is increasing, the effect of HIV infection on the process of aging is not fully understood. Understanding the complexity of aging with HIV by investigating the effect of the latter on different components of the innate and adaptive immune systems is important to reduce the impact of these comorbid conditions and improve the quality of life of PLHIV. The role of killer immunoglobulin receptors (KIRs), expressed on the surface of natural killer (NK) cells, and their human leukocyte antigen (HLA) ligands in the clearance, susceptibility to or disease progression following HIV infection is well established. However, data on the effect of KIR-HLA interaction in aging HIV-infected population and the development of non-AIDS-related comorbid conditions are lacking. Moreover, conflicting data exist on the role of regulatory T cells (Tregs) during HIV infection. The purpose of this review is to advance the current knowledge on the role of NK cells and Tregs while aging with HIV infection.

Short Communication: Decreased Plasma Calcitonin Gene-Related Peptide as a Novel Biomarker for HIV-1 Disease Progression

HIV-1 mucosal transmission in genital epithelia occurs through infection of Langerhans cells and subsequent transinfection of CD4⁺ T cells. We previously reported that the vasodilator neuropeptide calcitonin gene-related peptide (CGRP), secreted upon activation of sensory peripheral neurons that innervate all mucosal epithelia, significantly inhibits transinfection. To investigate the association between CGRP and HIV-1 during infection, we evaluated circulating CGRP levels in HIV-1-infected patients. Plasma was obtained from combination antiretroviral therapy (cART)-naive or cART-treated patients with primary/acute (PHI) or chronic (CHI) HIV-1 infection, as well as from individuals who naturally control HIV-1 infection, namely exposed seronegatives (ESNs), elite controllers (ECs), and long-term nonprogressors (LTNPs). CGRP plasma levels were measured using an enzyme immunoassay. Compared with healthy HIV-1-negative controls, CGRP plasma levels significantly decreased in PHI patients and even further in CHI patients, but remained unchanged in ESNs, ECs, and LTNPs. Moreover, CGRP plasma levels were restored to baseline upon cART in both PHI and CHI. Finally, CGRP plasma levels directly correlated with CD4⁺ T cell counts and inversely with viral loads. Altogether, CGRP could serve as a novel diagnostic plasma biomarker for progression of HIV-1 infection. Moreover, administration of CGRP to cART-naive HIV-1-infected patients, to compensate for CGRP decline, could help controlling on-going HIV-1 infection.

NK Cells in HIV Disease

Natural killer (NK) cells play a critical role in viral immunity. In the setting of HIV infection, epidemiologic and functional evidence support a role for NK cells in both protection from new infection and in viral control. Specifically, NK cells directly mediate immune pressure leading to virus evolution, and NK cell receptor genotypic profiles, clonal repertoires, and functional capacity have all been implicated in virus containment. In addition, indirect NK cell-mediated antibody-dependent cellular cytotoxicity has been linked to vaccine-induced protective immunity against HIV infection. With recent advances in our understanding of NK cell deficiency, development, memory-like responses, and editing of the adaptive immune system, the opportunities to direct and exploit NK cell antiviral immunity to target HIV have exponentially grown. In this review, we seek to highlight the intersections between discoveries in basic NK cell biology and the challenges of HIV chronic infection, vaccine development, and cure/eradication strategies.

Immune activation during acute HIV infection and the impact of early antiretroviral therapy

PURPOSE OF REVIEW

The purpose of this review is to outline recent data pertaining to mechanisms of immune activation in acute infection and describe new developments that seek to determine if early antiretroviral treatment can mitigate chronic immune activation.

RECENT FINDINGS

Following the detection of HIV RNA, highly activated CD8 T cells expand and peak approximately 2 weeks following peak viral load whereas levels of proinflammatory soluble markers coincide with a rise in viral load. Immune activation during acute infection is driven by many factors including pyroptosis, replicative capacity of the infecting virus, and loss of Th17 cells within the gut. Early antiretroviral therapy (ART), particularly if initiated in Fiebig I (HIV IgM-), preserved mucosal CD4 T cells, possibly preventing the release of microbial products associated with immune activation. Viral reservoirs were restricted by the early initiation of ART, and heightened systemic immune activation was partially prevented compared with chronic HIV infection. A strong correlation was found between the size of the viral reservoir and cellular immune activation.

SUMMARY

The timing of immune activation during acute infection occurs shortly after exposure. Recent studies demonstrated that ART mitigates inflammatory responses, preserves CD4 T cells, and limits reservoir seeding if provided early in acute HIV infection.