Identification of PD-1 as a Unique Marker for Failing Immune Reconstitution in HIV-1–Infected Patients on Treatment

Navigating the Roadblocks: Progress and Challenges in Cell-Based Therapies for Human Immunodeficiency Virus

Cell-based therapies represent a major advancement in the treatment and management of HIV/AIDS, with a goal to overcome the limitations of traditional antiretroviral therapy (ART). These innovative approaches not only promise a functional cure by reconstructing the immune landscape but also address the persistent viral reservoirs. For example, stem cell therapies have emerged from the foundational success of allogeneic hematopoietic stem cell transplantation in curing HIV infection in a limited number of cases. B cell therapies make use of genetically modified B cells constitutively expressing broadly neutralizing antibodies (bNAbs) against target viral particles and infected cells. Adoptive cell transfer (ACT), including TCR-T therapy, CAR-T cells, NK-CAR cells, and DC-based therapy, is adapted from cancer immunotherapy and repurposed for HIV eradication. In this review, we summarize the mechanisms through which these engineered cells recognize and destroy HIV-infected cells, the modification strategies, and their role in sustaining remission in the absence of ART. The review also addresses the challenges to cell-based therapies against HIV and discusses the recent advancements aimed at overcoming them.

HIV immunological non-responders are characterized by extensive immunosenescence and impaired lymphocyte cytokine production capacity

Introduction

Immunological non-responders (INR) are people living with HIV (PLHIV) who fail to fully restore CD4+ T-cell counts despite complete viral suppression with antiretroviral therapy (ART). INR are at higher risk for non-HIV related morbidity and mortality. Previous research suggest persistent qualitative defects.

Methods

The 2000HIV study (clinical trials NTC03994835) enrolled 1895 PLHIV, divided in a discovery and validation cohort. PLHIV with CD4 T-cell count <350 cells/mm3 after ≥2 years of suppressive ART were defined as INR and were compared to immunological responders (IR) with CD4 T-cell count >500 cells/mm3. Logistic and rank based regression were used to analyze clinical data, extensive innate and adaptive immunophenotyping, and ex vivo monocyte and lymphocyte cytokine production after stimulation with various stimuli.

Results

The discovery cohort consisted of 62 INR and 1224 IR, the validation cohort of 26 INR and 243 IR. INR were older, had more advanced HIV disease before starting ART and had more frequently a history of non-AIDS related malignancy. INR had lower absolute CD4+ T-cell numbers in all subsets. Activated (HLA-DR+, CD38+) and exhausted (PD1+) subpopulations were proportionally increased in CD4 T-cells. Monocyte and granulocyte immunophenotypes were comparable. INR lymphocytes produced less IL-22, IFN-γ, IL-10 and IL-17 to stimuli. In contrast, monocyte cytokine production did not differ. The proportions of CD4+CD38+HLA-DR+ and CD4+PD1+ subpopulations showed an inversed correlation to lymphocyte cytokine production.

Conclusions

INR compared to IR have hyperactivated and exhausted CD4+ T-cells in combination with lymphocyte functional impairment, while innate immune responses were comparable. Our data provide a rationale to consider the use of anti-PD1 therapy in INR.

Immune checkpoint inhibitors as potential therapy for reverting T-cell exhaustion and reverting HIV latency in people living with HIV

The immune system of people living with HIV (PLWH) is persistently exposed to antigens leading to systemic inflammation despite combination antiretroviral treatment (cART). This inflammatory milieu promotes T-cell activation and exhaustion. Furthermore, it produces diminished effector functions including loss of cytokine production, cytotoxicity, and proliferation, leading to disease progression. Exhausted T cells show overexpression of immune checkpoint molecules (ICs) on the cell surface, including programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), T-cell immunoglobulin and mucin-domain containing-3 (TIM-3), T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT), and lymphocyte activation gene-3 (LAG-3). The ICs also play a crucial role in T-cell exhaustion by reducing the immune response to cancer antigens. Immunotherapy based on immune checkpoint inhibitors (ICIs) has changed the management of a diversity of cancers. Additionally, the interest in exploring this approach in the setting of HIV infection has increased, including AIDS-defining cancers and non-AIDS-defining cancers in PLWH. To date, research on this topic suggests that ICI-based therapies in PLWH could be a safe and effective approach. In this review, we provide an overview of the current literature on the potential role of ICI-based immunotherapy not only in cancer remission in PLWH but also as a therapeutic intervention to restore immune response against HIV, revert HIV latency, and attain a functional cure for HIV infection.

HIV-1 DNA and Immune Activation Levels Differ for Long-Lived T-Cells in Lymph Nodes, Compared with Peripheral Blood, during Antiretroviral Therapy

Elucidating the mechanisms underlying the persistence and location of the HIV reservoir is critical for developing cure interventions. While it has been shown that levels of T-cell activation and the size of the HIV reservoir are greater in rectal tissue and lymph nodes (LN) than in blood, the relative contributions of T-cell subsets to this anatomic difference are unknown. We measured and compared HIV-1 DNA content, expression of the T-cell activation markers CD38 and HLA-DR, and expression of the exhaustion markers programmed cell death protein 1 (PD-1) and T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT) in naive, central memory (CM), transitional memory (TM), and effector memory (EM) CD4+ and CD8+ T-cells in paired blood and LN samples among 14 people with HIV who were receiving antiretroviral therapy. HIV-1 DNA levels, T-cell immune activation, and TIGIT expression were higher in LN than in blood, especially in CM and TM CD4+ T-cell subsets. Immune activation was significantly higher in all CD8+ T-cell subsets, and memory CD8+ T-cell subsets from LN had higher levels of PD-1 expression, compared with blood, while TIGIT expression levels were significantly lower in TM CD8+ T-cells. The differences seen in CM and TM CD4+ T-cell subsets were more pronounced among participants with CD4+ T-cell counts of <500 cells/μL within 2 years after antiretroviral therapy initiation, thus highlighting increased residual dysregulation in LN as a distinguishing feature of and a potential mechanism for individuals with suboptimal CD4+ T-cell recovery during antiretroviral therapy. IMPORTANCE This study provides new insights into the contributions of different CD4+ and CD8+ T-cell subsets to the anatomic differences between LN and blood in individuals with HIV who have optimal versus suboptimal CD4+ T-cell recovery. To our knowledge, this is the first study comparing paired LN and blood CD4+ and CD8+ T-cell differentiation subsets, as well as those subsets in immunological responders versus immunological suboptimal responders.

Ex Vivo Blockade of the PD-1 Pathway Improves Recall IFNγ Responses of HIV-Infected Persons on Antiretroviral Therapy

Despite antiretroviral therapy (ART), immune exhaustion persists in HIV infection and limits T cell responses to HIV or other pathogens. Moreover, HIV infection results in the loss of pre-existing immunity. Here, we investigated the effect of blocking the PD-1 pathway on recall IFNγ responses to tetanus toxoid (TT) and measles virus (MV) antigens in HIV-infected persons on ART with prior TT and MV immunity. The ex vivo treatment of lymphocytes with anti-PD-1 and anti-PD-L1 antibodies significantly increased TT- and MV-specific IFNγ responses. The responses to TT and MV antigens alone or in combination with antibodies blocking the PD-1 pathway positively correlated with CD4 T cell levels. Furthermore, T cell PD-1 expression levels inversely correlated with recall IFNγ responses in combination with antibodies blocking the PD-1 pathway but not with IFNγ responses to antigens only. Our study suggested that targeting the PD-1 pathway may boost vaccine-induced pre-existing immunity in HIV-infected persons on ART depending on the degree of immune exhaustion.

Allogeneic gene-edited HIV-specific CAR-T cells secreting PD-1 blocking scFv enhance specific cytotoxic activity against HIV Env+ cells invivo

HIV-specific chimeric antigen receptor (CAR) T-cells have been developed to target HIV-1 infected CD4⁺ T-cells that express HIV Env proteins. However, T cell exhaustion and the patient-specific autologous paradigm of CAR-T cell hurdled clinical applications. Here, we created HIV-specific CAR-T cells using human peripheral blood mononuclear cells and a 3BNC117-E27 (3BE) CAR construct that enabled the expression of programmed cell death protein (PD-1) -blocking scFv E27 and the single-chain variable fragment of the HIV-1-specific broadly neutralizing antibody 3BNC117 to target native HIV Env. Compared with T cells expressing 3BNC117-CAR alone, 3BE CAR-T cells showed greater cytotoxic activity against HIV Env⁺ cells with stronger proliferation capability, higher killing efficiency, and enhanced cytokine secretion in the presence of HIV Env-expressing cells. Furthermore, we manufactured TCR-deficient 3BE CAR-T cells through gene editing and demonstrated that these CAR-T cells could effectively kill HIV Env ​⁺ ​cells in vivo without the occurrence of severe graft-versus-host disease (GvHD) in NSG mice. These data suggest that we have provided a feasible approach to the generation of "off-the-shelf" anti-HIV CAR-T cells in combination with PD-1 checkpoint blockade immunotherapy, which can be a powerful therapeutic candidate for the functional cure of HIV.

Cellular and molecular insights into incomplete immune recovery in HIV/AIDS patients

Highly active antiretroviral therapy (ART) can effectively inhibit virus replication and restore immune function in most people living with human immunodeficiency virus (HIV). However, an important proportion of patients fail to achieve a satisfactory increase in CD4⁺ T cell counts. This state is called incomplete immune reconstitution or immunological nonresponse (INR). Patients with INR have an increased risk of clinical progression and higher rates of mortality. Despite widespread attention to INR, the precise mechanisms remain unclear. In this review, we will discuss the alterations in the quantity and quality of CD4⁺ T as well as multiple immunocytes, changes in soluble molecules and cytokines, and their relationship with INR, aimed to provide cellular and molecular insights into incomplete immune reconstitution.

The effect of age on CD4+ T-cell recovery in HIV-suppressed adult participants: a sub-study from AIDS Clinical Trial Group (ACTG) A5321 and the Bone Loss and Immune Reconstitution (BLIR) study

Older age could be a risk factor for suboptimal CD4+ T-cell recovery in HIV-infected patients despite successful viral suppression. However, evaluation of this effect could be confounded by age-related immune processes such as decreased thymus output, increased immune activation and exhaustion. Here, we established a semi-mechanistic population model simultaneously describing naïve and memory CD4+ T-cell trajectories in 122 participants. Covariate analysis accounting for immune activation showed that older age was significantly associated with faster apparent elimination rate of the naïve T-cells. In addition, female sex predicted slower apparent elimination rate of memory T-cells. Simulations showed that the median maximal CD4+ T-cell count on ART treatment was 593 cells/μL (IQR 442-794) in patients aged 50 years or above and 738 cells/μL (IQR 548-1002) in patients aged 18-35 years. The differences in the percentage of subjects achieving sufficient immune reconstitution (CD4+ T-cell count> 500 cells/μL) between the two age groups were 15, 21 and 26% at year 1, 4 years and steady state, respectively, suggesting that advanced age may have a greater impact on long-term CD4+ T-cell recovery.

Site of analysis matters - Ongoing complete response to Nivolumab in a patient with HIV/HPV related metastatic anal cancer and MLH1 mutation

Anal cancer is a rare disease with increasing incidence. In patients with locally recurrent or metastatic disease which cannot be treated with chemoradiotherapy or salvage surgery systemic first-line chemotherapy with carboplatin and paclitaxel is standard of care. For patients who progress after first-line therapy and are still eligible for second-line therapy Programmed cell death protein 1 (PD-1) antibodies are potential therapeutic options. However, prediction of response to immunotherapy is still challenging including anal cancer. We report here to our knowledge the first anal cancer case with microsatellite instability (MSI) due to MLH1 mutation and a deep and ongoing response to Nivolumab treatment. Namely, thorough analysis of the primary tumor as well as metastatic sites by next generation sequencing (NGS) revealed that MSI was formally only found in the metastatic sites but not in the primary tumor. Concomitantly, tumor mutational burden (TMB) was higher in the metastatic site than in the primary tumor. Therefore, we conclude that all anal cancer patients should be tested for MSI and whenever possible molecular analysis should be performed rather from metastatic sites than from the primary tumor.

Multidisciplinary approach to treatment with immune checkpoint inhibitors in patients with HIV, tuberculosis, or underlying autoimmune diseases

We reviewed the available information on the use of immune checkpoint inhibitors (ICIs) in populations with special conditions, namely, patients with HIV, tuberculosis, or underlying autoimmune disease. Available data show that treatment with ICIs is safe in patients with HIV; it is advisable, however, that these patients receive adequate antiretroviral therapy and have an undetectable viral load before ICIs are initiated. Tuberculosis reactivation has been reported with the use of ICIs, possibly due to immune dysregulation. Tuberculosis has also been associated with the use of immunosuppressors to treat immune-related adverse events (irAEs). Active tuberculosis must be ruled out in patients with symptoms or signs, and selected patients may benefit from screening for latent tuberculosis infection, although more data are required. Limited data exist regarding the safety of ICIs in patients with cancer and autoimmune disease. Data from observational studies suggest that up to 29% of patients with a preexisting autoimmune disease treated with an ICI present with an autoimmune disease flare, and 30% present with a de novo irAE of any type. The frequency of flares appears to differ according to the type of ICI received, with higher rates associated with PD-1/PD-L1 inhibitors. The most common autoimmune diseases for which patients reported flares with ICI therapy are rheumatoid arthritis, other inflammatory arthritis, and psoriasis. Most studies have reported flares or de novo irAEs associated with ICIs that were mild to moderate, with low rates of discontinuation and no deaths due to flares. Therefore, the use of ICIs in these patients is possible, but careful monitoring is required.

RKIP Pleiotropic Activities in Cancer and Inflammatory Diseases: Role in Immunity

Simple Summary

The human body consists of tissues and organs formed by cells. In each cell there is a switch that allows the cell to divide or not. In contrast, cancer cells have their switch on which allow them to divide and invade other sites leading to death. Over two decades ago, Doctor Kam Yeung, University of Toledo, Ohio, has identified a factor (RKIP) that is responsible for the on/off switch which functions normally in healthy tissues but is inactive or absent in cancers. Since this early discovery, many additional properties have been ascribed to RKIP including its role in inhibiting cancer metastasis and resistance to therapeutics and its role in modulating the normal immune response. This review describes all of the above functions of RKIP and suggesting therapeutics to induce RKIP in cancers to inhibit their growth and metastases as well as inhibit its activity to treat non-cancerous inflammatory diseases.

Abstract

Several gene products play pivotal roles in the induction of inflammation and the progression of cancer. The Raf kinase inhibitory protein (RKIP) is a cytosolic protein that exerts pleiotropic activities in such conditions, and thus regulates oncogenesis and immune-mediated diseases through its deregulation. Herein, we review the general properties of RKIP, including its: (i) molecular structure; (ii) involvement in various cell signaling pathways (i.e., inhibition of the Raf/MEK/ERK pathway; the NF-kB pathway; GRK-2 or the STAT-3 pathway; as well as regulation of the GSK3Beta signaling; and the spindle checkpoints); (iii) regulation of RKIP expression; (iv) expression’s effects on oncogenesis; (v) role in the regulation of the immune system to diseases (i.e., RKIP regulation of T cell functions; the secretion of cytokines and immune mediators, apoptosis, immune check point inhibitors and RKIP involvement in inflammatory diseases); and (vi) bioinformatic analysis between normal and malignant tissues, as well as across various immune-related cells. Overall, the regulation of RKIP in different cancers and inflammatory diseases suggest that it can be used as a potential therapeutic target in the treatment of these diseases.

Risk factors for immune-related adverse events: what have we learned and what lies ahead?

Immune checkpoint inhibitors (ICIs) have heralded the advent of a new era in oncology by holding the promise of prolonged survival in severe and otherwise treatment-refractory advanced cancers. However, the remarkable antitumor efficacy of these agents is overshadowed by their potential for inducing autoimmune toxic effects, collectively termed immune-related adverse events (irAEs). These autoimmune adverse effects are often difficult to predict, possibly permanent, and occasionally fatal. Hence, the identification of risk factors for irAEs is urgently needed to allow for prompt therapeutic intervention. This review discusses the potential mechanisms through which irAEs arise and summarizes the existing evidence regarding risk factors associated with the occurrence of irAEs. In particular, we examined available data regarding the effect of a series of clinicopathological and demographic factors on the risk of irAEs.

Enhanced Gut-Homing Dynamics and Pronounced Exhaustion of Mucosal and Blood CD4+ T Cells in HIV-Infected Immunological Non-Responders

Immunological non-responders (INR), a subgroup of people living with HIV (PLHIV) who fail to restore CD4⁺ T cell numbers upon effective antiretroviral treatment, have impaired gut mucosal barrier function and an inferior clinical prognosis compared with immunological responders (IR). The contribution of gut-homing and exhaustion of mucosal T cells to the INR phenotype was previously unknown. Flow cytometry analysis of mononuclear cells from peripheral blood and ileal and colonic lamina propria showed that INR had higher fractions of gut-homing CD4⁺ T cells in blood compared with IR. In addition, gut-homing cells were more likely to display signs of exhaustion in INR. The increased CD4⁺ T cell exhaustion in INR was ubiquitous and not restricted to subpopulations defined by activation, differentiation or regulatory T cell markers. In INR, colon CD4⁺ T cell exhaustion correlated negatively with the fraction of CD4⁺ T cells in the same compartment, this was not apparent in the ileum. The fraction of exhausted mucosal CD4⁺ T cells correlated with I-FABP and REG3α, markers of enterocyte damage. We conclude that alterations of gut-homing and exhaustion of T cells may contribute to impaired gut immune and barrier functions associated with immunological non-response in PLHIV.

Human Immunodeficiency Virus Infection Promotes Human Papillomavirus-Mediated Anal Squamous Carcinogenesis: An Immunologic and Pathobiologic Review

BACKGROUND

Anal squamous cell carcinoma (SCC) is a rare gastrointestinal malignancy with rising incidence, both in the United States and internationally. The primary risk factor for anal SCC is human papillomavirus (HPV) infection. However, there is a growing burden of disease in patients with human immunodeficiency virus (HIV) and HPV coinfection, with the incidence of anal SCC significantly increasing in this population. This is particularly true in HIV-infected men. The epidemiologic correlation between HIV-HPV coinfection and anal SCC is established; however, the immunologic mechanisms underlying this relationship are not well understood.

SUMMARY

HIV-related immunosuppression due to low circulating CD4+ T cells is one component of increased risk, but other mechanisms, such as the effect of HIV on CD8+ T lymphocyte tumor infiltration and the PD-1/PD-L1 axis in antitumor and antiviral response, is emerging as significant contributors. The goal of this article is to review existing research on HIV-HPV coinfected anal SCC and precancerous lesions, propose explanations for the detrimental synergy of HIV and HPV on the pathogenesis and immunologic response to HPV-associated cancers, and discuss implications for future treatments and immunotherapies in HIV-positive patients with HPV-mediated anal SCC. Key Messages: The incidence of anal squamous cell carcinoma is increased in human immunodeficiency virus (HIV)-infected patients, even in patients on highly active antiretroviral therapy. Locoregional HIV infection may enhance human papillomavirus oncogenicity. Chronic inflammation due to HIV infection may contribute to CD8+ T lymphocyte exhaustion by upregulating PD-1 expression, thereby blunting cytotoxic antitumor response.

Increased homeostatic cytokines and stability of HIV-infected memory CD4 T-cells identify individuals with suboptimal CD4 T-cell recovery on-ART

Clinical outcomes are inferior for individuals with HIV having suboptimal CD4 T-cell recovery during antiretroviral therapy (ART). We investigated if the levels of infection and the response to homeostatic cytokines of CD4 T-cell subsets contributed to divergent CD4 T-cell recovery and HIV reservoir during ART by studying virologically-suppressed immunologic responders (IR, achieving a CD4 cell count >500 cells/μL on or before two years after ART initiation), and virologically-suppressed suboptimal responders (ISR, did not achieve a CD4 cell count >500 cells/μL in the first two years after ART initiation). Compared to IR, ISR demonstrated higher levels of HIV-DNA in naïve, central (CM), transitional (TM), and effector (EM) memory CD4 T-cells in blood, both pre- and on-ART, and specifically in CM CD4 T-cells in LN on-ART. Furthermore, ISR had higher pre-ART plasma levels of IL-7 and IL-15, cytokines regulating T-cell homeostasis. Notably, pre-ART PD-1 and TIGIT expression levels were higher in blood CM and TM CD4 T-cells for ISR; this was associated with a significantly lower fold-changes in HIV-DNA levels between pre- and on-ART time points exclusively on CM and TM T-cell subsets, but not naïve or EM T-cells. Finally, the frequency of CM CD4 T-cells expressing PD-1 or TIGIT pre-ART as well as plasma levels of IL-7 and IL-15 predicted HIV-DNA content on-ART. Our results establish the association between infection, T-cell homeostasis, and expression of PD-1 and TIGIT in long-lived CD4 T-cell subsets prior to ART with CD4 T-cell recovery and HIV persistence on-ART.

Pembrolizumab for treatment of progressive multifocal leukoencephalopathy in primary immunodeficiency and/or hematologic malignancy: a case series of five patients

Progressive multifocal leukoencephalopathy is a rare opportunistic infection of the brain by John Cunningham polyomavirus in immune-compromised patients. In cases where no overt option for immune reconstitution is available [e.g., in patients with primary immunodeficiency (PID)], the disease is lethal in the majority of patients. Immune checkpoint inhibition has been applied in recent years with mixed outcomes. We present four novel patients and the follow-up of a previously published patient suffering from progressive multifocal leukoencephalopathy (PML) due to PID and/or hematologic malignancy who were treated with the immune checkpoint inhibitor pembrolizumab. In two patients with PID, symptoms improved and stabilized. One patient died because of worsening PML another of intracranial hemorrhage which was unrelated to PML or its treatment with pembrolizumab. The fifth patient suffered from PID and died of a pre-existing immune dysregulation, possibly exacerbated by pembrolizumab. The long-term follow-up of the first patient provides support for therapeutic decisions during this therapy and is the longest published clinical course of a patient with checkpoint inhibition for PML. We conclude that pembrolizumab can control PML symptoms long term in a subgroup of patients with PID, in our cases for 21 and 36 months. However, therapy must be started early because symptoms are only partially reversible. In light of severe adverse events, application of pembrolizumab is only justified if the prognosis for the individual patient is very poor.

Disease Progression in Children with Perinatal HIV Correlates with Increased PD-1+ CD8 T Cells that Coexpress Multiple Immune Checkpoints

BACKGROUND

PD-1 marks exhausted T cells, with weak effector functions. Adults living with HIV have increased levels of PD-1+ CD8 T cells that correlate with HIV disease progression, yet little is known about the role of PD-1+ CD8 T cells in children with perinatal HIV.

METHODS

We enrolled 76 Kenyan children with perinatal HIV and 43 children who were HIV unexposed and quantified PD-1 levels on CD8 T cells, their coexpression with immune checkpoints (IC) 2B4, CD160 and TIM3, correlates with immune activation and HIV disease progression and HIV-specific and non-specific proliferative responses.

RESULTS

PD-1+ CD8 T cell frequencies are elevated in children with perinatal HIV and associated with disease progression. The majority of PD-1+ CD8 T cells coexpress additional ICs. ART initiation lowers total PD-1 levels and coexpression of multiple ICs. The frequency of PD-1 + 2B4+CD160+TIM3- in PD-1+ CD8 T cells, predicts weaker HIV-specific proliferative responses, suggesting this subset is functionally exhausted.

CONCLUSION

Children with perinatal HIV have high PD-1+ CD8 T cells that are a heterogeneous population differentially coexpressing multiple ICs. Understanding the complex interplay of ICs is essential to guide the development of PD-1 directed immunotherapies for pediatric HIV remission and cure.

Markers of T Cell Exhaustion and Senescence and Their Relationship to Plasma TGF-β Levels in Treated HIV+ Immune Non-responders

Background: Immune non-responders (INR) are HIV+, ART-controlled (>2 yrs) people who fail to reconstitute their CD4 T cell numbers. Systemic inflammation and markers of T cell senescence and exhaustion are observed in INR. This study aims to investigate T cell senescence and exhaustion and their possible association with soluble immune mediators and to understand the immune profile of HIV-infected INR. Selected participants were <50 years old to control for the confounder of older age. Methods: Plasma levels of IL-6, IP10, sCD14, sCD163, and TGF-β and markers of T cell exhaustion (PD-1, TIGIT) and senescence (CD57, KLRG-1) were measured in ART-treated, HIV+ participants grouped by CD4 T cell counts (n = 63). Immune parameters were also measured in HIV-uninfected, age distribution-matched controls (HC; n = 30). Associations between T cell markers of exhaustion and senescence and plasma levels of immune mediators were examined by Spearman rank order statistics. Results: Proportions of CD4 T cell subsets expressing markers of exhaustion (PD-1, TIGIT) and senescence (CD57, KLRG-1) were elevated in HIV+ participants. When comparing proportions between INR and IR, INR had higher proportions of CD4 memory PD-1+, EM CD57+, TEM TIGIT+ and CD8 EM and TEM TIGIT+ cells. Plasma levels of IL-6, IP10, and sCD14 were elevated during HIV infection. IP10 was higher in INR. Plasma TGF-β levels and CD4 cycling proportions of T regulatory cells were lower in INR. Proportions of CD4 T cells expressing TIGIT, PD-1, and CD57 positively correlated with plasma levels of IL-6. Plasma levels of TGF-β negatively correlated with proportions of TIGIT+ and PD-1+ T cell subsets. Conclusions: INR have lower levels of TGF-β and decreased proportions of cycling CD4 T regulatory cells and may have difficulty controlling inflammation. IP10 is elevated in INR and is linked to higher proportions of T cell exhaustion and senescence seen in INR.

Infections and Immunotherapy in Lung Cancer: A Bad Relationship?

Infectious diseases represent a relevant issue in lung cancer patients. Bacterial and viral infections might influence the patients’ prognosis, both directly affecting the immune system and indirectly impairing the outcome of anticancer treatments, mainly immunotherapy. In this analysis, we aimed to review the current evidence in order to clarify the complex correlation between infections and lung cancer. In detail, we mainly explored the potential impact on immunotherapy outcome/safety of (1) bacterial infections, with a detailed focus on antibiotics; and (2) viral infections, discriminating among (a) human immune-deficiency virus (HIV), (b) hepatitis B/C virus (HBV-HCV), and (c) Sars-Cov-2. A series of studies suggested the prognostic impact of antibiotic therapy administration, timing, and exposure ratio in patients treated with immune checkpoint inhibitors, probably through an antibiotic-related microbiota dysbiosis. Although cancer patients with HIV, HBV, and HCV were usually excluded from clinical trials evaluating immunotherapy, some retrospective and prospective trials performed in these patient subgroups reported similar results compared to those described in not-infected patients, with a favorable safety profile. Moreover, patients with thoracic cancers are particularly at risk of COVID-19 severe outcomes and mortality. Few reports speculated about the prognostic implications of anticancer therapy, including immunotherapy, in lung cancer patients with concomitant Sars-Cov-2 infection, showing, to date, inconsistent results. The correlation between infectious diseases and immunotherapy remains to be further explored and clarified in the context of dedicated trials. In clinical practice, the accurate and prompt multidisciplinary management of lung cancer patients with infections should be encouraged in order to select the best treatment options for these patients, avoiding unexpected toxicities, while maintaining the anticancer effect.

The Role of Immunomodulatory Receptors in the Pathogenesis of HIV Infection: A Therapeutic Opportunity for HIV Cure?

Immune activation is the hallmark of HIV infection and plays a role in the pathogenesis of the disease. In the context of suppressed HIV RNA replication by combination antiretroviral therapy (cART), there remains immune activation which is associated to the HIV reservoirs. Persistent virus contributes to a sustained inflammatory environment promoting accumulation of "activated/exhausted" T cells with diminished effector function. These T cells show increased expression of immunomodulatory receptors including Programmed cell death protein (PD1), Cytotoxic T Lymphocyte Associated Protein 4 (CTLA4), Lymphocyte activation gene 3 (LAG3), T cell immunoglobulin and ITIM domain (TIGIT), T cell immunoglobulin and mucin domain containing 3 (TIM3) among others. More importantly, recent reports had demonstrated that, HIV infected T cells express checkpoint receptors, contributing to their survival and promoting maintenance of the viral reservoir. Therapeutic strategies are focused on viral reservoir elimination and/or those to achieve sustained cART-free virologic remission. In this review, we will discuss the immunological basis and the latest advances of the use of checkpoint inhibitors to treat HIV infection.

Definition of Immunological Nonresponse to Antiretroviral Therapy: A Systematic Review

BACKGROUND

Terms and criteria to classify people living with HIV on antiretroviral therapy who fail to achieve satisfactory CD4 T-cell counts are heterogeneous, and need revision and summarization.

METHODS

We performed a systematic review of PubMed original research articles containing a set of predefined terms, published in English between January 2009 and September 2018. The search retrieved initially 1360 studies, of which 103 were eligible. The representative terminology and criteria were extracted and analyzed.

RESULTS

Twenty-two terms and 73 criteria to define the condition were identified. The most frequent term was "immunological nonresponders" and the most frequent criterion was "CD4 T-cell count <350 cells/µL after ≥24 months of virologic suppression." Most criteria use CD4+ T-cell counts as a surrogate, either as an absolute value or as a change after a defined period of time [corrected]. Distinct values and time points were used. Only 9 of the 73 criteria were used by more than one independent research team. Herein we propose 2 criteria that could help to reach a consensus.

CONCLUSIONS

The high disparity in terms and criteria here reported precludes data aggregation and progression of the knowledge on this condition, because it renders impossible to compare data from different studies. This review will foster the discussion of terms and criteria to achieve a consensual definition.

Infectious Complications of Immune Checkpoint Inhibitors

The clearance of both tumors and microbes depends on highly coordinated immune responses that are sufficiently potent to kill malignant or microbial cells while avoiding immunopathology from an overly exuberant inflammatory response. A molecular understanding of the immune pathways that regulate these responses paved the way for the development of checkpoint inhibitors (CPIs) as a therapeutic strategy to boost endogenous antitumor immunity. CPIs have demonstrated survival benefits across a wide spectrum of cancers. While infectious complications of CPIs are uncommon, immune-related adverse events occur frequently and often require immunosuppressive therapies that increase the risk of infection.

Safety and Efficacy of Immune Checkpoint Inhibitor Therapy in Patients With HIV Infection and Advanced-Stage Cancer: A Systematic Review

Importance

Patients with HIV infection are at increased risk for cancer. Cancer is the leading cause of death among non-AIDS-defining illnesses in these patients. Immune checkpoint inhibitor (ICI) therapy has transformed the treatment of cancer. However, clinical trials of ICIs have historically excluded patients with HIV infection. The safety and efficacy profile of ICIs is unknown in this underrepresented population.

Objective

To summarize results on the safety and efficacy of ICI therapy in HIV-infected patients with advanced-stage cancer.

Evidence Review

This systematic review was conducted in accordance with PRISMA guidelines. A literature search of PubMed was performed on April 16, 2018, using the keyword HIV and the names of ICIs approved by the US Food and Drug Administration (ipilimumab, nivolumab, pembrolizumab, avelumab, atezolizumab, and durvalumab). Patients with HIV infection who were being treated with ICIs for advanced-stage cancer were included. In addition, abstracts and posters from major oncology and AIDS society annual meetings from 2016 through 2018 were reviewed.

Findings

Seventy-three patients (66 [90.4%] male; mean age, 56.1 years [range, 30.0-77.0 years]) were identified from 13 articles (11 case reports and 2 case series) and 4 meeting abstracts. Sixty-two patients were treated with anti-programmed cell death 1 (anti-PD-1) therapy, 6 with anti-cytotoxic T-lymphocyte antigen 4 (anti-CTLA-4) therapy, 4 with anti-PD-1/CTLA-4 therapy, and 1 with sequential ipilimumab and nivolumab therapy. Immune checkpoint inhibitor therapy was generally well tolerated, with grade 3 or higher immune-related adverse events noted in 6 of 70 patients (8.6%). Among 34 patients with known paired pretreatment and posttreatment HIV loads, HIV remained suppressed in 26 of the 28 (93%) with undetectable HIV load. Among the 25 with paired pretreatment and posttreatment CD4 cell counts, the counts increased (mean [SD] change, 12.3 [28.5] /μL). Objective response rates were 30% for non-small cell lung cancer, 27% for melanoma, and 63% for Kaposi sarcoma.

Conclusions and Relevance

Immune checkpoint inhibitor therapy for the treatment of advanced-stage cancer in patients with HIV infection was associated with no new safety signals. Immune checkpoint inhibitors may be a safe and efficacious treatment option in this patient population. Several ongoing prospective clinical trials will shed further light on the safety and efficacy of ICI therapy in HIV-infected patients with cancer.

Incomplete immune reconstitution in HIV/AIDS patients on antiretroviral therapy: Challenges of immunological non-responders

The morbidity and mortality of HIV type-1 (HIV-1)-related diseases were dramatically diminished by the grounds of the introduction of potent antiretroviral therapy, which induces persistent suppression of HIV-1 replication and gradual recovery of CD4⁺ T-cell counts. However, ∼10-40% of HIV-1-infected individuals fail to achieve normalization of CD4⁺ T-cell counts despite persistent virological suppression. These patients are referred to as "inadequate immunological responders," "immunodiscordant responders," or "immunological non-responders (INRs)" who show severe immunological dysfunction. Indeed, INRs are at an increased risk of clinical progression to AIDS and non-AIDS events and present higher rates of mortality than HIV-1-infected individuals with adequate immune reconstitution. To date, the underlying mechanism of incomplete immune reconstitution in HIV-1-infected patients has not been fully elucidated. In light of this limitation, it is of substantial practical significance to deeply understand the mechanism of immune reconstitution and design effective individualized treatment strategies. Therefore, in this review, we aim to highlight the mechanism and risk factors of incomplete immune reconstitution and strategies to intervene.

Treating cancer with immunotherapy in HIV-positive patients: A challenging reality

Immunotherapy has widely changed the management of different malignancies. However, efficacy and safety of immune checkpoint inhibitors (ICIs) are not well established in people living with HIV (PLWH). Population of HIV-positive patients has deeply changed after the introduction of modern antiretroviral therapy (ART) and available data of immunotherapy in this subgroup are inadequate considering that cancer has become a leading cause of death and morbidity in this population. Moreover, there are many similarities between cancer and infectious antigen stimulation so that ICIs are even under evaluation as specific HIV treatment. Most of literature on this topic is based on small case series that suggest that immunotherapy for PLWH seems to be as effective as in HIV-negative population with a good safety profile. In this article we review literature on HIV and immunotherapy and we collect many case series available in different malignancies, with a brief focus on lung cancer.

Circulating Th1, Th2, Th17, Treg, and PD-1 Levels in Patients with Brucellosis

Brucella is an intracellular infection bacterium; the pathogenesis of Brucella and chronicity of infection may be related to the immune response of T cells. T lymphocytes mainly participate in cellular immune response. The extent of different T cell subsets imbalanced and their function dysregulated in patients with brucellosis remain not explicit. We grouped patients at different stages (acute, chronic, and convalescent). The frequencies of Th1, Th2, Th17, Treg, and PD-1 (programmed cell death protein 1) in peripheral blood were examined by flow cytometry, and the expressions of T lymphocyte cytokines in serum were detected by cytometric bead array. Th1, Th17, and Treg cell immunity was predominant in the acute stage, while Th2, Th17, and Treg cell immunity was predominant in the chronic stage. The expressions of PD-1 on CD4+ and CD8+ T lymphocytes were significantly different in acute and chronic patients. The percentages of Th1 cells in convalescent patients were still higher than those in healthy controls within one year after withdrawal. The expression of T lymphocyte cytokines in serum was different in patients at different stages. These results indicate that peripheral T lymphocyte immunity was involved in patients with brucellosis and represents a target for the preclinical and clinical assessment of novel immunomodulating therapeutics. The patients' immune function had not completely recovered in a short period of time during convalescence, so long-term follow-up of convalescent patients is needed.

Lymphopenia-induced proliferation of CD4 T-cells is associated with CD4 T-lymphocyte exhaustion in treated HIV-infected patients

Background & objectives:

Under the lymphopenic condition, T-cells divide to maintain their peripheral pool size. Profound chronic lymphopenia in some treated HIV-infected patients, characterized by poor T-cell recovery, might result in intensive homeostatic proliferation and can cause T-cell exhaustion and/or senescence. The present study was undertaken to evaluate the homeostatic proliferation of CD4⁺ T-cells in treated HIV-infected individuals, and to determine the amount of phenotypically exhausted and senescent CD4 T-lymphocytes.

Methods:

Thirty seven treated HIV-infected patients with suppressed HIV viral load (<50 copies/ml) were studied. Patients were divided into two groups: immunological non-responders (INRs) with CD4⁺ T-cells <350/μl (n=16) and immunological responders (IRs) with CD4⁺ T-cells >350/μl (n=21). T-cell subsets [naïve, central memory (CM), and effector memory (EM)] and proportions of cycling (Ki-67⁺), senescent (CD57⁺) and exhausted (PD-1⁺) T-lymphocytes were assessed using flow cytometry.

Results:

CD4⁺ T-cell cycling rate was higher in INRs than in IRs due to more extensive proliferation of CM, 4.7 vs 2.7 per cent (P <0.01) and EM, 4.8 vs 3.2 per cent (P <0.05). The percentages of CD4⁺ Ki-67⁺ CM and EM T-lymphocytes were inversely related to the CD4⁺ T-cell counts in the appropriate subset, r=–0.584 (P <0.001) and r=–0.556, (P <0.001), respectively. Exhaustion [24.2 vs 16.7% (P <0.01)], but not senescence [7.1 vs 10.8% (P>0.05)] was more pronounced in the INR group than in the IR group. The frequency of CD4⁺ Ki-67⁺ CM T-cells was related to the proportion of CD4⁺ PD-1⁺ cells of the same subset, r=0.789 (P <0.001). The numbers of CD4⁺ Ki-67⁺ PD-1⁺ CM and EM T-cells were substantially higher in INRs than in IRs.

Interpretation & conclusions:

The present data indicated that intensive homeostatic proliferation contributed to the T-cell exhaustion in HIV-infection.

Phenotype, Polyfunctionality, and Antiviral Activity of in vitro Stimulated CD8+ T-Cells From HIV+ Subjects Who Initiated cART at Different Time-Points After Acute Infection

Since anti-HIV treatment cannot cure the infection, many strategies have been proposed to eradicate the viral reservoir, which still remains as a major challenge. The success of some of these strategies will rely on the ability of HIV-specific CD8+ T-cells (CD8TC) to clear reactivated infected cells. Here, we aimed to investigate the phenotype and function of in vitro expanded CD8TC obtained from HIV+ subjects on combination antiretroviral therapy (cART), either initiated earlier (median = 3 months postinfection, ET: Early treatment) or later (median = 20 months postinfection, DT: Delayed treatment) after infection. Peripheral blood mononuclear cells from 12 DT and 13 ET subjects were obtained and stimulated with Nef and Gag peptide pools plus IL-2 for 14 days. ELISPOT was performed pre- and post-expansion. CD8TC memory/effector phenotype, PD-1 expression, polyfunctionality (CD107a/b, IFN-γ, IL-2, CCL4 (MIP-1β), and/or TNF-α production) and antiviral activity were evaluated post-expansion. Magnitude of ELISPOT responses increased after expansion by 103 times, in both groups. Expanded cells were highly polyfunctional, regardless of time of cART initiation. The memory/effector phenotype distribution was sharply skewed toward an effector phenotype after expansion in both groups although ET subjects showed significantly higher proportions of stem-cell and central memory CD8TCs. PD-1 expression was clustered in HIV-specific effector memory CD8TCs, subset that also showed the highest proportion of cytokine-producing cells. Moreover, PD-1 expression directly correlated with CD8TC functionality. Expanded CD8TCs from DT and ET subjects were highly capable of mediating antiviral activity, measured by two different assays. Antiviral function directly correlated with the proportion of fully differentiated effector cells (viral inhibition assay) as well as with CD8TC polyfunctionality and PD-1 expression (VITAL assay). In sum, we show that, despite being dampened in subjects on cART, the HIV-specific CD8TC response could be selectively stimulated and expanded in vitro, presenting a high proportion of cells able to carry-out multiple effector functions. Timing of cART initiation had an impact on the memory/effector differentiation phenotype, most likely reflecting how different periods of antigen persistence affected immune function. Overall, these results have important implications for the design and evaluation of strategies aimed at modulating CD8TCs to achieve the HIV functional cure.

PD-1 has a unique capacity to inhibit allergen-specific human CD4+ T cell responses

T lymphocytes have a crucial role in initiating and promoting type I allergies. Their responses are tightly regulated by numerous activating and inhibitory signals provided by APCs. Here we have addressed the role of the major coinhibitory receptors PD-1, CTLA-4, BTLA and LAG-3 in allergen-specific CD4⁺ T cell responses. PBMCs of healthy individuals and 41 patients allergic to house dust mites, birch, grass or mugwort pollen were stimulated with allergenic extracts and expression of coinhibitory receptors on responding CD4⁺ T cells was assessed. Blocking antibodies to PD-1, CTLA-4, BTLA and LAG-3 were used to evaluate the role of coinhibitory pathways. Allergen-specific CD4⁺ T cells showed strong upregulation of PD-1, LAG-3 and CTLA-4 upon stimulation, whereas BTLA was downregulated. Blockade of PD-1 strongly enhanced proliferation and cytokine production (IL-10; T_H1 cytokines IFN-γ, TNF-α; T_H2 cytokines IL-5, IL-13) of allergen-specific CD4⁺ T cells derived from allergic as well as non-allergic individuals. BTLA blockade enhanced proliferation but not cytokine production in response to house dust mite extract. Blocking LAG-3 was ineffective and surprisingly, we observed reduced proliferation and cytokine production in presence of a CTLA-4 antibody. Our results point to a unique potency of PD-1 pathways to dampen allergen-specific human T cells.

HIV-Infected Subjects With Poor CD4 T-Cell Recovery Despite Effective Therapy Express High Levels of OX40 and α4β7 on CD4 T-Cells Prior Therapy Initiation

Background

HIV-infected subjects with suboptimal CD4 restoration despite suppressive combined antiretroviral treatment (cART) (immunodiscordant subjects) have been classically characterized after a variable period of time under cART. Recently, we have reported that an increased frequency of proliferating CD4 T-cells in these subjects is already present before the cART onset. The potential contribution of peripheral compensatory homeostatic proliferation (HP) is yet unknown. We aimed to analyze the expression of HP-related cellular markers on CD4 T-cells of immunodiscordant subjects before cART.

Methods

We analyzed the expression of OX40 and α4β7 on peripheral CD4 T-cells from immunodiscordant and control subjects (n = 21 each group) before cART initiation, and also on available follow-up samples (after 24 month of suppressive cART). Additionally, we tested the expression of these markers in an in vitro system for the study of human HP processes.

Results

Immunodiscordant subjects showed increased levels of OX40 and α4β7 on CD4 T-cells before cART initiation. While the cART tended to reduce these levels, immunodiscordant subjects still maintained comparatively higher levels of OX40 and α4β7 after 24 months under suppressive cART. These HP-related markers were upregulated in vitro during the human HP, especially during the fast HP.

Conclusion

Our results are compatible with exacerbated HP processes in immunodiscordant subjects, already before the cART onset.

Differentiation and Function of Follicular CD8 T Cells During Human Immunodeficiency Virus Infection

The combination antiretroviral therapeutic (cART) regime effectively suppresses human immunodeficiency virus (HIV) replication and prevents progression to acquired immunodeficiency diseases. However, cART is not a cure, and viral rebound will occur immediately after treatment is interrupted largely due to the long-term presence of an HIV reservoir that is composed of latently infected target cells that maintain a quiescent state or persistently produce infectious viruses. CD4 T cells that reside in B-cell follicles within lymphoid tissues, called follicular helper T cells (TFH), have been identified as a major HIV reservoir. Due to their specialized anatomical structure, HIV-specific CD8 T cells are largely insulated from this TFH reservoir. It is increasingly clear that the elimination of TFH reservoirs is a key step toward a functional cure for HIV infection. Recently, several studies have suggested that a fraction of HIV-specific CD8 T cells can differentiate into a CXCR5-expressing subset, which are able to migrate into B-cell follicles and inhibit viral replication. In this review, we discuss the differentiation and functions of this newly identified CD8 T-cell subset and propose potential strategies for purging TFH HIV reservoirs by utilizing this unique population.

Hospital length of stay and cost burden of HIV, tuberculosis, and HIV-tuberculosis coinfection among pregnant women in the United States

BACKGROUND

We sought to determine hospital length of stay (LOS) and cost burden associated with hospital admissions among pregnant women with HIV monoinfection, tuberculosis (TB) monoinfection, or HIV-TB coinfection in the United States.

METHODS

Analysis covered the period from 2002-2014 using data from the Nationwide Inpatient Sample. Relevant ICD-9-CM codes were used to determine HIV and TB status. Costs associated with hospitalization were calculated and adjusted to 2010 dollars using the medical care component of the Consumer Price Index.

RESULTS

We found modest annual average reduction in HIV, TB, and HIV-TB coinfection rates over the study period. The mean LOS was lowest among mothers free of HIV or TB disease and highest among those with HIV-TB coinfection. The average LOS among mothers diagnosed with TB monoinfection was 60% higher than for those with HIV monoinfection. The cost associated with pregnancy-related hospital admissions among mothers with HIV was approximately 30% higher than disease-free mothers, and the cost more than doubled among patients with TB monoinfection or HIV-TB coinfection.

CONCLUSIONS

TB significantly increased hospital care cost among HIV-positive and HIV-negative pregnant women.

YY1 Upregulates Checkpoint Receptors and Downregulates Type I Cytokines in Exhausted, Chronically Stimulated Human T Cells

T cells infiltrate affected organs in chronic infections and malignancy, but they may fail to eradicate virus-infected cells or tumor because of exhaustion. This report describes a Yin Yang-1 (YY1)-centered mechanism for diverse components that have been correlated with exhaustion. Utilizing an in vitro reconstruction of chronic T cell activation, YY1 is shown to positively regulate the checkpoint receptors PD1, Lag3, and Tim3 and to negatively regulate the type I cytokines interleukin-2 (IL-2) (in collaboration with Ezh2 histone methyltransferase) and interferon gamma (IFN-?). Other tests suggest that IL-2 failure drives a large component of cytotoxic functional decline rather than solely checkpoint receptor-ligand interactions that have been the focus of current anti-exhaustion therapies. Clinical evaluations confirm elevated YY1 and Ezh2 in melanoma tumor-infiltrating lymphocytes and in PD1+ T cells in patients with HIV. Exhaustion is revealed to be an active process as the culmination of repetitive two-signal stimulation in a feedback loop via CD3/CD28?p38MAPK/JNK?YY1? exhaustion.

Mechanisms of CD8+ T cell-mediated suppression of HIV/SIV replication

In this article, we summarize the role of CD8⁺ T cells during natural and antiretroviral therapy (ART)-treated HIV and SIV infections, discuss the mechanisms responsible for their suppressive activity, and review the rationale for CD8⁺ T cell-based HIV cure strategies. Evidence suggests that CD8⁺ T cells are involved in the control of virus replication during HIV and SIV infections. During early HIV infection, the cytolytic activity of CD8⁺ T cells is responsible for control of viremia. However, it has been proposed that CD8⁺ T cells also use non-cytolytic mechanisms to control SIV infection. More recently, CD8⁺ T cells were shown to be required to fully suppress virus production in ART-treated SIV-infected macaques, suggesting that CD8⁺ T cells are involved in the control of virus transcription in latently infected cells that persist under ART. A better understanding of the complex antiviral activities of CD8⁺ T cells during HIV/SIV infection will pave the way for immune interventions aimed at harnessing these functions to target the HIV reservoir.

Expression of PD-1 and Tim-3 markers of T-cell exhaustion is associated with CD4 dynamics during the course of untreated and treated HIV infection

Introduction

T-cell exhaustion has been involved in the pathogenesis of HIV infection. We have longitudinally analyzed PD1 and Tim3 surrogate markers of T-cells exhaustion, in parallel with other markers of HIV progression, and its potential association with CD4 changes in treated and untreated infection.

Patients and methods

96 HIV patients, 49 of them followed in the absence of cART (cART-naïve group) and 47 after initiation of cART (cART group) were included and followed for a median of 43 [IQR: 31–60] months. PD1 and Tim3 expression, CD8 T-cells activation, recent thymic emigrants, activation/apoptosis and turnover of CD4 cells were assessed at baseline and during follow up. Univariate and multivariate associations with CD4 evolution were explored.

Results

Parameters significantly associated with CD4 depletion in cART-naïve group were: baseline level (p = 0.02) and variation (p = 0.002) of PD1 and Tim3 co-expression on CD8, and variation of CD95 expression on CD4 (p = 0.007). Parameters significantly associated with CD4 restoration in cART group were: baseline level of CD38+HLADR- subset of CD8 (p = 0.01), variation of PD1 expression on CD8 (p = 0.036), variation of Tim3 expression on CD4 (p = 0.039) and variation of CD95 expression on CD4 (p = 0.035).

Conclusions

Our results suggest that PD1 and Tim3 markers of exhaustion have a pivotal role in CD4 dynamics in HIV patients and its down-regulation would be a desirable effect of immunotherapies aimed to restore CD4 T-cell pool during progression of HIV infection.

Class-modeling analysis reveals T-cell homeostasis disturbances involved in loss of immune control in elite controllers

BACKGROUND

Despite long-lasting HIV replication control, a significant proportion of elite controller (EC) patients may experience CD4 T-cell loss. Discovering perturbations in immunological parameters could help our understanding of the mechanisms that may be operating in those patients experiencing loss of immunological control.

METHODS

A case-control study was performed to evaluate if alterations in different T-cell homeostatic parameters can predict CD4 T-cell loss in ECs by comparing data from EC patients showing significant CD4 decline (cases) and EC patients showing stable CD4 counts (controls). The partial least-squares-class modeling (PLS-CM) statistical methodology was employed to discriminate between the two groups of patients, and as a predictive model.

RESULTS

Herein, we show that among T-cell homeostatic alterations, lower levels of naïve and recent thymic emigrant subsets of CD8 cells and higher levels of effector and senescent subsets of CD8 cells as well as higher levels of exhaustion of CD4 cells, measured prior to CD4 T-cell loss, predict the loss of immunological control.

CONCLUSIONS

These data indicate that the parameters of T-cell homeostasis may identify those EC patients with a higher proclivity to CD4 T-cell loss. Our results may open new avenues for understanding the mechanisms underlying immunological progression despite HIV replication control, and eventually, for finding a functional cure through immune-based clinical trials.

Malnutrition in HIV-Infected Children Is an Indicator of Severe Disease with an Impaired Response to Antiretroviral Therapy

This observational study aimed to describe immunopathogenesis and treatment outcomes in children with and without severe acute malnutrition (SAM) and HIV-infection. We studied markers of microbial translocation (16sDNA), intestinal damage (iFABP), monocyte activation (sCD14), T-cell activation (CD38, HLA-DR) and immune exhaustion (PD1) in 32 HIV-infected children with and 41 HIV-infected children without SAM prior to initiation of antiretroviral therapy (ART) and cross-sectionally compared these children to 15 HIV-uninfected children with and 19 HIV-uninfected children without SAM. We then prospectively measured these markers and correlated them to treatment outcomes in the HIV-infected children at 48 weeks following initiation of ART. Plasma levels of 16sDNA, iFABP and sCD14 were measured by quantitative real time PCR, ELISA and Luminex, respectively. T cell phenotype markers were measured by flow cytometry. Multiple regression analysis was performed using generalized linear models (GLMs) and the least absolute shrinkage and selection operator (LASSO) approach for variable selection. Microbial translocation, T cell activation and exhaustion were increased in HIV-uninfected children with SAM compared to HIV-uninfected children without SAM. In HIV-infected children microbial translocation, immune activation, and exhaustion was strongly increased but did not differ by SAM-status. SAM was associated with increased mortality rates early after ART initiation. Malnutrition, age, microbial translocation, monocyte, and CD8 T cell activation were independently associated with decreased rates of CD4% immune recovery after 48 weeks of ART. SAM is associated with increased microbial translocation, immune activation, and immune exhaustion in HIV-uninfected children and with worse prognosis and impaired immune recovery in HIV-infected children on ART.

HIV-TB Coinfection among 57 Million Pregnant Women, Obstetric Complications, Alcohol Use, Drug Abuse, and Depression

Objective

HIV and tuberculosis represent diseases of major public health importance worldwide. Very little is known about HIV-TB coinfection among pregnant women, especially from industrialized settings. In this study, we examined the association between TB, HIV, and HIV-TB coinfection among pregnant mothers and obstetric complications, alcohol use, drug abuse, and depression.

Method

We examined inpatient hospital discharges in the United States from January 1, 2002, through December 31, 2014. We employed multivariable survey logistic regression to generate adjusted estimates for the association between infection status and study outcomes.

Results

We analyzed approximately 57 million records of pregnant women and their delivery information. HIV-TB coinfection was associated with the highest risks for several obstetric complications, alcohol use, and drug abuse. The risk for alcohol abuse was more than twice as high among HIV-monoinfected as compared to TB-monoinfected mothers. That risk gap more than doubled with HIV-TB coinfection. Both HIV-monoinfected and HIV-TB coinfected mothers experienced similarly increased risks for depression.

Conclusions

Mothers with HIV-TB coinfection experienced relatively heightened risks for obstetric complications, alcohol use, and drug abuse. The findings of this study underscore the importance of augmenting and enhancing social and structural support systems for HIV-TB coinfected pregnant women.

Antibodies targeting BTLA or TIM-3 enhance HIV-1 specific T cell responses in combination with PD-1 blockade

Persistent stimulation with antigens derived from viruses that establish chronic infections or tumour antigens results in the exhaustion of T cells. Coinhibitory receptors like PD-1 and CTLA-4 function as immune checkpoints on exhausted T cells. Blocking these molecules with antibodies improve immunity to cancer cells. Immune checkpoint inhibitors targeting other coinhibitory receptors might have a similar role in improving T cell function and thus also utility in cancer therapy. Using HIV-specific T cells as a model for exhaustion we have evaluated the capacity of antibodies targeting TIM-3, BTLA, CD160, LAG-3 and CTLA-4 alone or in combination with a PD-1 antibody to enhance proliferation and cytokine production in response to Gag and Nef peptides. Antibodies targeting BTLA and TIM-3 enhanced CD8 T cell proliferation. Moreover, our results indicate that blocking BTLA and TIM-3 in combination with PD-1 might be especially effective in enhancing responses of exhausted human T cells.

The Immune Interaction between HIV-1 Infection and Mycobacterium tuberculosis

The modulation of tuberculosis (TB)-induced immunopathology caused by human immunodeficiency virus (HIV)-1 coinfection remains incompletely understood but underlies the change seen in the natural history, presentation, and prognosis of TB in such patients. The deleterious combination of these two pathogens has been dubbed a "deadly syndemic," with each favoring the replication of the other and thereby contributing to accelerated disease morbidity and mortality. HIV-1 is the best-recognized risk factor for the development of active TB and accounts for 13% of cases globally. The advent of combination antiretroviral therapy (ART) has considerably mitigated this risk. Rapid roll-out of ART globally and the recent recommendation by the World Health Organization (WHO) to initiate ART for everyone living with HIV at any CD4 cell count should lead to further reductions in HIV-1-associated TB incidence because susceptibility to TB is inversely proportional to CD4 count. However, it is important to note that even after successful ART, patients with HIV-1 are still at increased risk for TB. Indeed, in settings of high TB incidence, the occurrence of TB often remains the first presentation of, and thereby the entry into, HIV care. As advantageous as ART-induced immune recovery is, it may also give rise to immunopathology, especially in the lower-CD4-count strata in the form of the immune reconstitution inflammatory syndrome. TB-immune reconstitution inflammatory syndrome will continue to impact the HIV-TB syndemic.

Aberrant plasma IL-7 and soluble IL-7 receptor levels indicate impaired T-cell response to IL-7 in human tuberculosis

T-cell proliferation and generation of protective memory during chronic infections depend on Interleukin-7 (IL-7) availability and receptivity. Regulation of IL-7 receptor (IL-7R) expression and signalling are key for IL-7-modulated T-cell functions. Aberrant expression of soluble (s) and membrane-associated (m) IL-7R molecules is associated with development of autoimmunity and immune failure in acquired immune deficiency syndrome (AIDS) patients. Here we investigated the role of IL-7/IL-7R on T-cell immunity in human tuberculosis. We performed two independent case-control studies comparing tuberculosis patients and healthy contacts. This was combined with follow-up examinations for a subgroup of tuberculosis patients under therapy and recovery. Blood plasma and T cells were characterised for IL-7/sIL-7R and mIL-7R expression, respectively. IL-7-dependent T-cell functions were determined by analysing STAT5 phosphorylation, antigen-specific cytokine release and by analysing markers of T-cell exhaustion and inflammation. Tuberculosis patients had lower soluble IL-7R (p < 0.001) and higher IL-7 (p < 0.001) plasma concentrations as compared to healthy contacts. Both markers were largely independent and aberrant expression normalised during therapy and recovery. Furthermore, tuberculosis patients had lower levels of mIL-7R in T cells caused by post-transcriptional mechanisms. Functional in vitro tests indicated diminished IL-7-induced STAT5 phosphorylation and impaired IL-7-promoted cytokine release of Mycobacterium tuberculosis-specific CD4⁺ T cells from tuberculosis patients. Finally, we determined T-cell exhaustion markers PD-1 and SOCS3 and detected increased SOCS3 expression during therapy. Only moderate correlation of PD-1 and SOCS3 with IL-7 expression was observed. We conclude that diminished soluble IL-7R and increased IL-7 plasma concentrations, as well as decreased membrane-associated IL-7R expression in T cells, reflect impaired T-cell sensitivity to IL-7 in tuberculosis patients. These findings show similarities to pathognomonic features of impaired T-cell functions and immune failure described in AIDS patients.

IL-7 is important for the development and homeostasis of T cells and promotes antigen-specific T-cell responses. Aberrant expression of plasma IL-7 and soluble IL-7R are found in autoimmune diseases and chronic viral infections. In AIDS patients—especially those who fail to reconstitute T-cell numbers during therapy—impaired IL-7-promoted T-cell functions indicated T-cell exhaustion/senescence. In order to evaluate the potential impact of IL-7 on tuberculosis, we characterised various parameters involved in the IL-7-response of tuberculosis patients and healthy contacts. Despite IL-7 being available at higher plasma levels among tuberculosis patients, the T-cell response to IL-7 was impaired when compared to healthy contacts. Soluble IL-7R levels were aberrantly low in plasma during acute tuberculosis but did not account for impaired IL-7 usage. Chronic inflammation in tuberculosis patients—reflected by increased IL-6 plasma levels—did not account for dysfunctional T-cell responses and analysed T-cell exhaustion markers were only moderately correlated. Our findings demonstrate that availability of IL-7 alone is not sufficient to promote protective T-cell immunity against tuberculosis. We describe aberrant IL-7/soluble IL-7R expression and impaired IL-7-mediated T-cell functions in tuberculosis patients with similarities and differences to described IL-7 dysregulation seen in patients with AIDS.

Durable complete response to nivolumab in a patient with HIV and metastatic non-small cell lung cancer

Programmed death 1 (PD-1) inhibitors have been shown to increase overall survival in non-small cell lung cancer (NSCLC) patients. HIV patients have increased expression of PD-1 on their T-cell surfaces. We describe a patient with well-controlled HIV and NSCLC who underwent treatment with nivolumab and had a durable complete response (CR) with his viral load remaining undetectable. To date there is only one case report of a cancer patient with melanoma and with HIV treated with a programmed death ligand 1 (PD-L1) inhibitor. The majority of clinical trials involving PD-1 and PD-L1 inhibitors exclude HIV patients.

CD4+ T cells from HIV-1 patients with impaired Th1 effector responses to Mycobacterium tuberculosis exhibit diminished histone and nucleoprotein signatures

HIV+ patients have an increased risk for tuberculosis disease despite clinical management with ARTs. We established a culture model of Mtb-infection in PBMCs from HIV+ PPD+ donors on suppressive ART (median 6.4years) with negligible viral loads (median<50copies/mL) and stable CD4+ T cell counts (517cells/mm^3). We observed that HIV+ patient lymphocytes harbored a recruitment defect to Mtb-infected monocytes. To investigate these immune defects on a per cell basis, purified CD4+ T cells from HIV patients were assessed by label-free quantification protein mass spectrometry. CD4+ T cells from HIV patients displayed diminished nucleoprotein levels - notably of histone variant H2a.Z and ribonucleoprotein A1. Only within healthy donors, transcriptional regulatory histone variant H2a.Z expression was correlated to the extent of IFN-γ induction upon Mtb-infection. Our findings may explain why HIV patients exhibit prolonged immune cell dysfunction despite suppressive ART, and implicate a per cell defect of CD4+ T cells.

Higher levels of IL-6, CD4 turnover and Treg frequency are already present before cART in HIV-infected subjects with later low CD4 recovery

Immunological characterization of HIV-infected subjects with low CD4-recovery (LR-subjects) has been extensively performed after a variable period of combined antiretroviral therapy (cART). We now explore immunological alterations present before the cART onset. In a case-control study, we selected pre-cART samples of HIV-subjects with and without low CD4-recovery after cART (n = 21 per group). CD4 T-cell activation, senescence and exhaustion related markers were not found specifically altered before cART initiation. On the other hand, we found that LR-subjects before cART already showed increased levels of IL6 (p = 0.009) and increased frequencies of Ki67+CD4⁺ T-cells (p = 0.026), CD45RA-CD27+CD4⁺ T-cells (p = 0.008) and Treg (p = 0.001), as well as increased expression of CD95 and CD127 on CD4 T-cells (p = 0.016; p = 0.032, respectively). These parameters characterize the immunological damage in LR-subjects before the cART onset and could be associated to the mechanisms hindering the subsequent CD4 recovery.

Blocking type I interferon signaling enhances T cell recovery and reduces HIV-1 reservoirs

Despite the efficient suppression of HIV-1 replication that can be achieved with combined antiretroviral therapy (cART), low levels of type I interferon (IFN-I) signaling persist in some individuals. This sustained signaling may impede immune recovery and foster viral persistence. Here we report studies using a monoclonal antibody to block IFN-α/β receptor (IFNAR) signaling in humanized mice (hu-mice) that were persistently infected with HIV-1. We discovered that effective cART restored the number of human immune cells in HIV-1-infected hu-mice but did not rescue their immune hyperactivation and dysfunction. IFNAR blockade fully reversed HIV-1-induced immune hyperactivation and rescued anti-HIV-1 immune responses in T cells from HIV-1-infected hu-mice. Finally, we found that IFNAR blockade in the presence of cART reduced the size of HIV-1 reservoirs in lymphoid tissues and delayed HIV-1 rebound after cART cessation in the HIV-1-infected hu-mice. We conclude that low levels of IFN-I signaling contribute to HIV-1-associated immune dysfunction and foster HIV-1 persistence in cART-treated hosts. Our results suggest that blocking IFNAR may provide a potential strategy to enhance immune recovery and reduce HIV-1 reservoirs in individuals with sustained elevations in IFN-I signaling during suppressive cART.

Inflammation Perturbs the IL-7 Axis, Promoting Senescence and Exhaustion that Broadly Characterize Immune Failure in Treated HIV Infection

BACKGROUND

HIV-infected patients who fail to normalize CD4 T cells despite suppressive antiretroviral therapy have impaired immune homeostasis: diminished naive T-cell numbers, elevated T-cell turnover, senescence, and inflammation.

METHODS

Blood samples from immune failures (n = 60), immune successes (n = 20), and healthy controls (n = 20) were examined for plasma interleukin (IL)-7 levels, for cellular expression of the IL-7Rα chain (CD127), for the exhaustion and senescence markers programed death 1 (PD-1) and CD57, and for the survival factor Bcl2. Because both inflammatory and homeostatic cytokines can induce T-cell cycling, we also examined the effects of these mediators on exhaustion and senescence markers.

RESULTS

Plasma levels of IL-7 were elevated and both CD4 and CD8 T-cell CD127 expression was decreased in immune failure. Plasma levels of IL-7 correlated directly with naive CD4 T-cell counts in immune success and inversely with T-cell cycling (Ki67) in healthy controls and immune success, but not in immune failure. CD4 T-cell density of PD-1 was increased and Bcl2+ CD4 T cells were decreased in immune failure but not in immune success, whereas the proportion of T cells expressing CD57 was increased in immune failure. PD-1 and CD57 were induced on CD4 but not CD8 T cells by stimulation in vitro with inflammatory IL-1β or homeostatic (IL-7) cytokines.

CONCLUSIONS

Perturbation of the IL-7/IL-7 receptor axis, increased T-cell turnover, and increased senescence may reflect dysregulated responses to both homeostatic and inflammatory cytokines in immune failure patients.

Update and New Directions in Therapeutics for Neurological Complications of HIV Infections

The pace of therapeutic developments in HIV presents unique challenges to the neurologist caring for patients. Combination antiretroviral therapy (cART) is remarkably effective in suppressing viral replication, preventing, and often even reversing disease progression. Still, not every patient benefits from cART for a variety of reasons, ranging from the cost of therapy and the burden of lifelong daily treatment to side effects and inadequate access to medical care. Treatment failure inevitably leads to disease progression and opportunistic complications. Many of these complications, even those that are treatable, produce permanent neurological disability. With ART, immune recovery itself may paradoxically lead to severe neurological disease; strategies for managing so-called immune reconstitution inflammatory syndrome are beginning to show benefits. Effective cART may nevertheless leave in its wake persistent neurocognitive impairment. Treatments for persistent impairment despite virologic suppression and good immune recovery are being tested but are not yet proven. As we shall see, these treatments target several proposed mechanisms including cerebral small vessel disease, which is highly prevalent in HIV. Most recently, an ambitious initiative has been undertaken to develop interventions to eradicate HIV. This will require elimination of all infectious forms of viral nucleic acid throughout the body. The influence of these interventions on the brain remains to be characterized. Meanwhile, clinical investigators continue to develop antiretroviral treatments that optimize effectiveness, convenience, and tolerability, while minimizing long-term toxicities.

Increase in frequencies of circulating Th-17 cells correlates with microbial translocation, immune activation and exhaustion in HIV-1 infected patients with poor CD4 T-cell reconstitution

We analyzed the association of circulating Th-17 cells (cTh-17) with immune activation (IA), immune exhaustion (IE) and regulatory T-cells (T-regs) in 20 human immunodeficiency virus-1 (HIV-1) infected patients with impaired restoration of CD4 T-cell counts despite prolonged suppression of plasma viremia (discordant) and compared it with 20 HIV-1 infected patients showing good immunologic and virologic responses (concordant) following highly active antiretroviral therapy (HAART). Discordant HIV-1 infected patients showed significantly higher frequencies of cTh-17 cells compared to concordant patients and healthy controls after PMA+Ionomicin stimulation. Discordant patients also showed higher CD4 T-cell immune activation (HLA-DR+CD38+) than concordant patients which directly correlated with microbial translocation. Additionally, CD4 T-cells of discordant patients showed higher frequencies of CD4 T-cells expressing multiple immune exhaustion markers (Tim3+PD-1+) which correlated with immune activation indicating that combined analysis of inhibitory molecules along with PD-1 might be a better predictor for immune exhaustion of CD4 T-cells. Increased cTh-17 cell frequency correlated inversely with CD4 T-cell percentages and absolute counts and directly with CD4 T-cell immune activation and T-reg frequencies. Persistent CD4 T-cell immune activation might favor differentiation of activated CD4 T-cells toward cTh-17 phenotype in discordant patients. Discordant patients had significantly lower baseline CD4 T-cell counts and higher viral load at the initiation of HAART and higher immune activation and immune exhaustion after being on HAART for long time indicating that these factors might be associated with an increase in cTh-17 cell frequency, thus, increasing the risk of disease progression despite virologic control.

HIV-specific CD8⁺ T cells and HIV eradication

After the success of combination antiretroviral therapy (cART) to treat HIV infection, the next great frontier is to cure infected persons, a formidable challenge. HIV persists in a quiescent state in resting CD4+ T cells, where the replicative enzymes targeted by cART are not active. Although low levels of HIV transcripts are detectable in these resting cells, little to no viral protein is produced, rendering this reservoir difficult to detect by the host CD8+ T cell response. However, recent advances suggest that this state of latency might be pharmacologically reversed, resulting in viral protein expression without the adverse effects of massive cellular activation. Emerging data suggest that with this approach, infected cells will not die of viral cytopathic effects, but might be eliminated if HIV-specific CD8+ T cells can be effectively harnessed. Here, we address the antiviral properties of HIV-specific CD8+ T cells and how these cells might be harnessed to greater effect toward achieving viral eradication or a functional cure.