Upregulation of PD-1 expression on HIV-specific CD8+ T cells leads to reversible immune dysfunction

Smoking and HIV-1 Infection Promote Retention of CD8+ T Cells in the Airway Mucosa

Smoking and HIV-1 infection are risk factors for COPD, which is among the most common comorbid conditions in people living with HIV-1. HIV-1 infection leads to persistent expansion of CD8+ T cells, and CD8+ T cell-mediated inflammation has been implicated in COPD pathogenesis. In this study, we investigated the effects of HIV-1 infection and smoking on T cell dynamics in patients at risk of COPD. Bronchoalveolar lavage (BAL), endobronchial brushings and blood from HIV-1 infected and uninfected non-smokers and smokers were analyzed by flow cytometry, and lungs were imaged by computed tomography. Chemokines were measured in BAL fluid, and CD8+ T cell chemotaxis in the presence of cigarette smoke extract was assessed in vitro. HIV-1 infection increased CD8+ T cells in the BAL, but this increase was abrogated by smoking. Smokers had reduced BAL levels of the T cell-recruiting chemokines CXCL10 and CCL5, and cigarette smoke extract inhibited CXCL10 and CCL5 production by macrophages and CD8+ T cell transmigration in vitro. In contrast to the BAL, CD8+ T cells in endobronchial brushings were increased in HIV-1 infected smokers, driven by an accumulation of effector memory T cells in the airway mucosa and an increase in tissue resident memory T cells. Mucosal CD8+ T cell numbers inversely correlated with lung aeration, suggesting an association with inflammation and remodeling. HIV-1 infection and smoking lead to retention of CD8+ T cells within the airway mucosa.

Pre-existing Simian Immunodeficiency Virus Infection Increases Expression of T Cell Markers Associated with Activation during Early Mycobacterium tuberculosis Coinfection and Impairs TNF Responses in Granulomas

Tuberculosis (TB) is the leading infectious cause of death among people living with HIV. People living with HIV are more susceptible to contracting Mycobacterium tuberculosis and often have worsened TB disease. Understanding the immunologic defects caused by HIV and the consequences it has on M. tuberculosis coinfection is critical in combating this global health epidemic. We previously showed in a model of SIV and M. tuberculosis coinfection in Mauritian cynomolgus macaques (MCM) that SIV/M. tuberculosis-coinfected MCM had rapidly progressive TB. We hypothesized that pre-existing SIV infection impairs early T cell responses to M. tuberculosis infection. We infected MCM with SIVmac239, followed by coinfection with M. tuberculosis Erdman 6 mo later. Although similar, TB progression was observed in both SIV⁺ and SIV-naive animals at 6 wk post-M. tuberculosis infection; longitudinal sampling of the blood (PBMC) and airways (bronchoalveolar lavage) revealed a significant reduction in circulating CD4⁺ T cells and an influx of CD8⁺ T cells in airways of SIV⁺ animals. At sites of M. tuberculosis infection (i.e., granulomas), SIV/M. tuberculosis-coinfected animals had a higher proportion of CD4⁺ and CD8⁺ T cells expressing PD-1 and TIGIT. In addition, there were fewer TNF-producing CD4⁺ T cells in granulomas of SIV/M. tuberculosis-coinfected animals. Taken together, we show that concurrent SIV infection alters T cell phenotypes in granulomas during the early stages of TB disease. As it is critical to establish control of M. tuberculosis replication soon postinfection, these phenotypic changes may distinguish the immune dysfunction that arises from pre-existing SIV infection, which promotes TB progression.

Hepatocellular cancer therapy in patients with HIV infection: Disparities in cancer care, trials enrolment, and cancer-related research

In the highly active antiretroviral therapy (HAART) era, hepatocellular carcinoma (HCC) is arising as a common late complication of human immunodeficiency virus (HIV) infection, with a great impact on morbidity and mortality. Though HIV infection alone may not be sufficient to promote hepatocarcinogenesis, the complex interaction of HIV with hepatitis is a main aspect influencing HCC morbidity and mortality.

Data about sorafenib effectiveness and safety in HIV-infected patients are limited, particularly for patients who are on HAART. However, in properly selected subgroups, outcomes may be comparable to those of HIV-uninfected patients. Scarce data are available for those other systemic treatments, either tyrosine kinase inhibitors, as well as immune checkpoint inhibitors (ICIs), which have been added to our therapeutic armamentarium. This review examines the influence of HIV infection on HCC development and natural history, summarizes main data on systemic therapies, offers some insight into possible mechanisms of T cell exhaustion and reversal of HIV latency with ICIs and issues about clinical trials enrollment. Nowadays, routine exclusion of HIV-infected patients from clinical trial participation is totally inappropriate, since it leaves a number of patients deprived of life-prolonging therapies.

Inducible HIV-1 Reservoir Quantification: Clinical Relevance, Applications and Advancements of TILDA

The presence of a stable HIV-1 reservoir persisting over time despite effective antiretroviral suppression therapy precludes a cure for HIV-1. Characterizing and quantifying this residual reservoir is considered an essential prerequisite to develop and validate curative strategies. However, a sensitive, reproducible, cost-effective, and easily executable test is still needed. The quantitative viral outgrowth assay is considered the gold standard approach to quantify the reservoir in HIV-1-infected patients on suppressive ART, but it has several limitations. An alternative method to quantify the viral reservoir following the reactivation of latent HIV-1 provirus detects multiply-spliced tat/rev RNA (msRNA) molecules by real-time PCR [tat/rev induced limiting dilution assay (TILDA)]. This article provides a perspective overview of the clinical relevance, various applications, recent advancements of TILDA, and how the assay has contributed to our understanding of the HIV-1 reservoir.

Reversal of the CD8+ T-Cell Exhaustion Induced by Chronic HIV-1 Infection Through Combined Blockade of the Adenosine and PD-1 Pathways

Background

Targeting immune checkpoints for HIV treatment potentially provides a double benefit resulting from the ability to restore viral-specific CD8⁺ T-cell functions and enhance HIV production from reservoir cells. Despite promising pre-clinical data, PD-1 blockade alone in HIV-1-infected patients with advanced cancer has shown limited benefits in controlling HIV, suggesting the need for additional targets beyond PD-1. CD39 and PD-1 are highly co-expressed on CD8⁺ T cells in HIV-1 infection. However, the characteristics of CD39 and PD-1 dual-positive CD8⁺ T-cell subsets in chronic HIV-1 infection remain poorly understood.

Methods

This study enrolled 72 HIV-1-infected patients, including 40 treatment naïve and 32 ART patients. A total of 11 healthy individuals were included as controls. Different subsets of CD8⁺ T cells defined by CD39 and/or PD-1 expression were studied by flow cytometry. The relationships between the frequencies of the different subsets and parameters indicating HIV-1 disease progression were analyzed. Functional (i.e., cytokine secretion, viral inhibition) assays were performed to evaluate the impact of the blockade of adenosine and/or PD-1 signaling on CD8⁺ T cells.

Results

The proportions of PD-1⁺, CD39⁺, and PD-1⁺CD39⁺ CD8⁺ T cells were significantly increased in treatment naïve patients but were partially lowered in patients on antiretroviral therapy. In treatment naïve patients, the proportions of PD-1⁺CD39⁺ CD8⁺ T cells were negatively correlated with CD4⁺ T-cell counts and the CD4/CD8 ratio, and were positively correlated with viral load. CD39⁺CD8⁺ T cells expressed high levels of the A2A adenosine receptor and were more sensitive to 2-chloroadenosine-mediated functional inhibition than their CD39^- counterparts. In vitro, a combination of blocking CD39/adenosine and PD-1 signaling showed a synergic effect in restoring CD8⁺ T-cell function, as evidenced by enhanced abilities to secrete functional cytokines and to kill autologous reservoir cells.

Conclusion

In patients with chronic HIV-1 infection there are increased frequencies of PD-1⁺, CD39⁺, and PD-1⁺CD39⁺ CD8⁺ T cells. In treatment naïve patients, the frequencies of PD-1⁺CD39⁺ CD8⁺ T cells are negatively correlated with CD4⁺ T-cell counts and the CD4/CD8 ratio and positively correlated with viral load. Combined blockade of CD39/adenosine and PD-1 signaling in vitro may exert a synergistic effect in restoring CD8⁺ T-cell function in HIV-1-infected patients.

CXCR3 and CXCR5 are highly expressed in HIV-1-specific CD8 central memory T cells from infected patients

New ways of characterizing CD8⁺ memory T cell responses in chronic infections are based on the measurement of chemokine receptor expression (CXCR3, CXCR5, and CX3CR1). We applied these novel phenotyping strategies to chronic HIV infection by comparing healthy donors (HDs), HIV-infected patients receiving antiretroviral therapy (ART), and spontaneous HIV controllers (HICs). In all groups, the memory cells exhibited high proportion of CXCR3⁺ cells. Proportions of CXCR5⁺ and CX3CR1⁺ cells were preferentially observed among central memory cells (Tcm) and effector memory cells (Tem) respectively. Chronic controlled HIV infection impacted the chemokine receptor profile of both HIV-specific and nonspecific CD8⁺ T cells. In total CD8⁺ T cells, the proportions of CXCR3^- CXCR5^- CX3CR1^- Tcm and Tem were lower in HIV-infected patients than in HDs with subtle differences between ART and HICs. Such phenotyping strategy also revealed differences in exhaustion and senescence phenotypes, the CXCR3⁺ CXCR5⁺ CX3CR1^- being more exhausted and senescent than the CXCR3⁺ CXCR5^- CX3CR1^- Tcm fraction. Among HIV-specific CD8⁺ T cells, the vast majority of Tcm cells were CXCR3⁺ and CXCR5⁺ cells in contrast with their nonspecific counterparts. In conclusion, the addition of migration markers contributes to better characterize Tcm/Tem compartment.

Epigenetic Features of HIV-Induced T-Cell Exhaustion Persist Despite Early Antiretroviral Therapy

T cell dysfunction occurs early following HIV infection, impacting the emergence of non-AIDS morbidities and limiting curative efforts. ART initiated during primary HIV infection (PHI) can reverse this dysfunction, but the extent of recovery is unknown. We studied 66 HIV-infected individuals treated from early PHI with up to three years of ART. Compared with HIV-uninfected controls, CD4 and CD8 T cells from early HIV infection were characterised by T cell activation and increased expression of the immune checkpoint receptors (ICRs) PD1, Tim-3 and TIGIT. Three years of ART lead to partial – but not complete – normalisation of ICR expression, the dynamics of which varied for individual ICRs. For HIV-specific cells, epigenetic profiling of tetramer-sorted CD8 T cells revealed that epigenetic features of exhaustion typically seen in chronic HIV infection were already present early in PHI, and that ART initiation during PHI resulted in only a partial shift of the epigenome to one with more favourable memory characteristics. These findings suggest that although ART initiation during PHI results in significant immune reconstitution, there may be only partial resolution of HIV-related phenotypic and epigenetic changes.

Assessment of nivolumab in HIV-Infected patients with advanced non-small cell lung cancer after prior chemotherapy. The IFCT-1602 CHIVA2 phase 2 clinical trial

IMPORTANCE

Therapies targeting immune checkpoints, such as the programmed cell death 1 (PD-1) receptor, have become the standard-of-care for patients with non-small cell lung cancer (NSCLC), but people living with HIV (PLWH) were excluded from these studies.

OBJECTIVE

To evaluate the efficacy and tolerability of nivolumab in PLWH with advanced NSCLC.

DESIGN

The CHIVA2 study was a nonrandomized, open-label, phase 2 clinical trial in PLWH with previously treated advanced NSCLC.

SETTING

National multicenter prospective study.

PARTICIPANTS

patients had viral load of <200 copies/mL, regardless of their CD4+ T-cell count.

INTERVENTION

Nivolumab was administered in second or third line, as monotherapy intravenously at 3 mg/kg every 2 weeks, until disease progression or limiting toxicity.

MAIN OUTCOMES AND MEASURES

The primary endpoint was disease control rate, evaluated using the Response Evaluation Criteria in Solid Tumors, version 1.1. Adverse events were graded using the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0.

RESULTS

Sixteen patients with advanced NSCLC were enrolled: 14 (88 %) were men, median age was 58 years (range: 44-71), and all were smokers. The median duration of nivolumab treatment was 3.5 months (range: 0.5-26.5). The median follow-up was 23.6 months. Disease control rate was 62.5 % for 15 evaluable patients at 8 weeks (2 with partial response, 8 with stable disease, and 5 with disease progression). Twelve (75 %) patients had treatment-related adverse events, which were mild or moderate, except for one patient experiencing severe pruritus, onycholysis, and pemphigoid. There were no opportunistic infections or unexpected immune-related events. HIV viral load was stable during treatment. An increase in proliferating CD8+ and CD4+ T-cells was observed after 3 nivolumab cycles in a subgroup of 9 patients.

CONCLUSIONS AND RELEVANCE

Second/third-line nivolumab treatment was well-tolerated and beneficial in PLWH with NSCLC. Future trials should investigate immune checkpoint inhibitors in first-line settings.

TRIAL REGISTRATION

EudraCT.ema.europa.eu registration number: 2016-003796-22.

CD8+ T-Cell Mediated Control of HIV-1 in a Unique Cohort With Low Viral Loads

A unique population of HIV-1 infected individuals can control infection without antiretroviral therapy. These individuals fall into a myriad of categories based on the degree of control (low or undetectable viral load), the durability of control over time and the underlying mechanism (i.e., possession of protective HLA alleles or the absence of critical cell surface receptors). In this study, we examine a cohort of HIV-1 infected individuals with a documented history of sustained low viral loads in the absence of therapy. Through in vitro analyses of cells from these individuals, we have determined that infected individuals with naturally low viral loads are capable of controlling spreading infection in vitro in a CD8⁺ T-cell dependent manner. This control is lost when viral load is suppressed by antiretroviral therapy and correlates with a clinical CD4:CD8 ratio of <1. Our results support the conclusion that HIV-1 controllers with low, but detectable viral loads may be controlling the virus due to an effective CD8⁺ T-cell response. Understanding the mechanisms of control in these subjects may provide valuable understanding that could be applied to induce a functional cure in standard progressors.

Loss of CD96 Expression as a Marker of HIV-Specific CD8+ T-Cell Differentiation and Dysfunction

Persistent immune activation and inflammation in people living with HIV (PLWH) are associated with immunosenescence, premature aging and increased risk of non-AIDS comorbidities, with the underlying mechanisms not fully understood. In this study, we show that downregulation of the T-cell immunoglobulin receptor CD96 on CD8⁺ T cells from PLWH is associated with decreased expression of the co-stimulatory receptors CD27 and CD28, higher expression of the senescence marker CD57 and accumulation of a terminally differentiated T-cell memory phenotype. In addition, we show that CD96-low CD8⁺ T-cells display lower proliferative potential compared to their CD96-high counterparts and that loss of CD96 expression by HIV-specific CD8⁺ T-cells is associated with a suboptimal response to HIV antigens. In conclusion, our results suggest that CD96 marks CD8⁺ T-cells with competent responses to HIV and the loss of its expression might be used as a biomarker for CD8⁺ T-cell senescence and dysfunction in PLWH.

Programmed cell death-1 single-nucleotide polymorphism rs10204525 is associated with human immunodeficiency virus type 1 RNA viral load in HIV-1-infected Moroccan subjects

Human Immunodeficiency Virus (HIV-1) infections are characterized by dysfunctional cellular and humoral antiviral immune responses. The progressive loss of effector functions in chronic viral infection has been associated with the up-regulation of programmed death-1 (PD-1), a negative regulator of activated T cells and Natural Killer cells. In HIV-1 infection, increased levels of PD-1 expression correlate with CD8 + T-cell exhaustion. In vitro, PD-1 blockade using PD-1 antibodies led to an increase in HIV-1 specific CD8 + T and memory B cell proliferation. We aimed to investigate the impact of PDCD1 rs10204525 polymorphism on HIV-1 susceptibility, AIDS development, and treatment response outcomes in HIV-1 infection in a Moroccan population. A total of 214 HIV-1 seropositive and 250 seronegative subjects were enrolled to investigate the association between the between the single-nucleotide polymorphism (SNP) rs10204525 of PDCD1 gene and HIV-1 pathogenesis using a predesigned TaqMan SNP genotyping assay. No significant association was found between rs10204525 and susceptibility to HIV-1 infection and AIDS development (p > 0.05). Genotype frequencies were significantly associated with the viral load before ART (p = 0.0105). HIV-1 viral load was significantly higher among subjects with the CC compared to TT genotype (p = 0.0043). In treated subjects, the median of viral load levels was significantly higher in CC and CT groups than TT subjects (p < 0.005). However, analysis of the correlation between CD4 + T-cell levels and PDCD1 polymorphism before and after ART showed no significant difference (p > 0.05). Our results demonstrated that rs10204525 polymorphism does not affect HIV-1 infection. However, this polymorphism may affect the response to treatment as measured by RNA viral load levels.

A participant-derived xenograft model of HIV enables long-term evaluation of autologous immunotherapies

HIV-specific CD8⁺ T cells partially control viral replication and delay disease progression, but they rarely provide lasting protection, largely due to immune escape. Here, we show that engrafting mice with memory CD4⁺ T cells from HIV⁺ donors uniquely allows for the in vivo evaluation of autologous T cell responses while avoiding graft-versus-host disease and the need for human fetal tissues that limit other models. Treating HIV-infected mice with clinically relevant HIV-specific T cell products resulted in substantial reductions in viremia. In vivo activity was significantly enhanced when T cells were engineered with surface-conjugated nanogels carrying an IL-15 superagonist, but it was ultimately limited by the pervasive selection of a diverse array of escape mutations, recapitulating patterns seen in humans. By applying mathematical modeling, we show that the kinetics of the CD8⁺ T cell response have a profound impact on the emergence and persistence of escape mutations. This “participant-derived xenograft” model of HIV provides a powerful tool for studying HIV-specific immunological responses and facilitating the development of effective cell-based therapies.

Selective downregulation of natural killer activating receptors on NK cells and upregulation of PD-1 expression on T cells in children with severe and/or recurrent Herpes simplex virus infections

Severe, recurrent or atypical Herpes simplex virus (HSV) infections are still posing clinical and diagnostic problem in clinical immunology facilities. However, the molecular background of this disorder is still unclear. The aim of this study was to investigate the expression of activating receptors on NK cells (CD16, NKp46, NKG2D, NKp80, 2B4, CD48 and NTB-A) and checkpoint molecule PD-1 on T lymphocytes and NK cells, in patients with severe and/or recurrent infections with HSV and age-matched healthy control subjects. As a result, we noticed that patients with severe and/or recurrent infection with HSV had significantly lower percentage of CD16^brightCD56^dim and higher percentage of CD16^dimCD56^bright NK cell subsets, when compared to control subjects, which may be associated with abnormal NK cell maturation during chronic HSV infection. Patients had also significantly downregulated expression of CD16 receptor on CD16^bright NK cells. The expression of activating receptors was significantly reduced on patients' NK cells - either both the percentage of NK cells expressing the receptor and MFI of its expression (NKp46, NKp80 and 2B4 on CD16^brightCD56^dim cells and NKp46 on CD16^dimCD56^bright cells) or only MFI (NKG2D on both NK cell subsets). It should be noted that the reduction of receptor expression was limited to NK cells, since there was no differences in the percentage of receptor-positive cells or MFI on T cells. However, NTB-A receptor was the only one which expression was not only simultaneously changed in patients' NK and T cells, but also significantly upregulated on CD16^dimCD56^bright NK cell and CD8⁺ cell subsets. Patients had also upregulated proportion of CD4⁺ T cells expressing PD-1. Thus, we suggest that an increased percentage of PD-1⁺ cells may represent an independent indirect mechanism of downregulation of antiviral response, separate from the reduction of NK cell activating receptors expression. Altogether, our studies indicate two possible mechanisms which may promote perpetuation of HSV infection: 1) selective inhibition of activating receptors on NK cells, but not on T cells, and 2) upregulation of checkpoint molecule PD-1 on CD4⁺ T cells.

Shocking HIV-1 with immunomodulatory latency reversing agents

The "shock-and-kill" strategy is one of the most explored HIV-1 cure approaches to eliminate latent virus. This strategy is based on HIV-1 reactivation using latency reversing agents (LRAs) to reactivate latent proviruses (the "shock" phase) and to induce subsequent elimination of the reactivated cells by immune responses or virus-induced cytopathic effects (the "kill" phase). Studies using immunomodulatory LRAs such as blockers of immune checkpoint molecules, toll-like receptor agonists, cytokines and CD8⁺ T cell depleting antibodies showed promising potential as LRAs inducing directly or indirectly cellular pathways known to control HIV transcription. However, the precise molecular mechanisms by which these immunomodulatory LRAs reverse latency remain incompletely understood. Together with the heterogenous nature of HIV-1 latency, this lack of understanding complicates efforts to develop more efficient and safer cure strategies. Hence, deciphering those mechanisms is pivotal in designing approaches to eliminate latent HIV infection.

Optimal Maturation of the SIV-Specific CD8+ T Cell Response after Primary Infection Is Associated with Natural Control of SIV: ANRS SIC Study

Highly efficient CD8⁺ T cells are associated with natural HIV control, but it has remained unclear how these cells are generated and maintained. We have used a macaque model of spontaneous SIVmac251 control to monitor the development of efficient CD8⁺ T cell responses. Our results show that SIV-specific CD8⁺ T cells emerge during primary infection in all animals. The ability of CD8⁺ T cells to suppress SIV is suboptimal in the acute phase but increases progressively in controller macaques before the establishment of sustained low-level viremia. Controller macaques develop optimal memory-like SIV-specific CD8⁺ T cells early after infection. In contrast, a persistently skewed differentiation phenotype characterizes memory SIV-specific CD8⁺ T cells in non-controller macaques. Accordingly, the phenotype of SIV-specific CD8⁺ T cells defined early after infection appears to favor the development of protective immunity in controllers, whereas SIV-specific CD8⁺ T cells in non-controllers fail to gain antiviral potency, feasibly as a consequence of early defects imprinted in the memory pool.

T cell immune discriminants of HIV reservoir size in a pediatric cohort of perinatally infected individuals

The size of the latent HIV reservoir is associated with the timing of therapeutic interventions and overall health of the immune system. Here, we demonstrate that T cell phenotypic signatures associate with viral reservoir size in a cohort of HIV vertically infected children and young adults under durable viral control, and who initiated anti-retroviral therapy (ART) <2 years old. Flow cytometry was used to measure expression of immune activation (IA), immune checkpoint (ICP) markers, and intracellular cytokine production after stimulation with GAG peptides in CD4 and CD8 T cells from cross-sectional peripheral blood samples. We also evaluated the expression of 96 genes in sort-purified total CD4 and CD8 T cells along with HIV-specific CD4 and CD8 T cells using a multiplexed RT-PCR approach. As a measure of HIV reservoir, total HIV-DNA quantification by real-time PCR was performed. Poisson regression modeling for predicting reservoir size using phenotypic markers revealed a signature that featured frequencies of PD-1+CD4 T cells, TIGIT+CD4 T cells and HIV-specific (CD40L+) CD4 T cells as important predictors and it also shows that time of ART initiation strongly affects their association with HIV-DNA. Further, gene expression analysis showed that the frequencies of PD-1+CD4 T cells associated with a CD4 T cell molecular profile skewed toward an exhausted Th1 profile. Our data provide a link between immune checkpoint molecules and HIV persistence in a pediatric cohort as has been demonstrated in adults. Frequencies of PD-1+ and TIGIT+CD4 T cells along with the frequency of HIV-specific CD4 T cells could be associated with the mechanism of viral persistence and may provide insight into potential targets for therapeutic intervention.

Low HIV reservoir size is associated with positive outcomes of therapeutic approaches and better immune function. Here, we identified a 9-marker T cell immune signature based on phenotypic flow cytometry data that associated with total HIV DNA measurements in a pediatric cohort of 34 perinatally infected participants with sustained viral control. Notably, frequencies of PD-1+ CD4 T cells and TIGIT+ CD4 T cells were positively correlated and HIV-specific (CD40L+) CD4 T cells were negatively correlated with HIV DNA, and were impacted by time of ART initiation. Gene expression analysis by multiplex RT-PCR showed that the frequencies of PD-1+ CD4 T cells associated with an exhausted Th1 molecular profile in CD4 T cells. This signature could inform future therapeutic studies and provide mechanistic insight on HIV persistence in perinatally infected HIV.

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.

In-vitro Immunomodulatory activity of Azadirachta indica A.Juss. Ethanol: water mixture against HIV associated chronic CD4+ T-cell activation/ exhaustion

BACKGROUND

In Sub-Saharan Africa, herbal therapy continues to be utilized for HIV-1 disease management. However, the therapeutic benefits of these substances remain ambiguous. To date, little is known about the effects of these plant extracts on chronic CD4 + T-cell activation and exhaustion which is partly driven by HIV-1 associated microbial translocation.

METHODS

Effects of Azadirachta indica, Momordica foetida and Moringa oleifera ethanol: water mixtures on cell viability were evaluated using the Guava PCA system. Then, an in-vitro cell culture model was developed to mimic CD4+ T cell exposures to antigens following HIV-1 microbial translocation. In this, peripheral blood mononuclear cells (PBMCs) isolated from HIV negative (n = 13), viral load < 1000 copies per mL (n = 10) and viral load > 1000 copies per mL (n = 6) study participants from rural Uganda were treated with Staphylococcus enterotoxin B (SEB). Then, the candidate plant extract (A. indica) was added to test the potential to inhibit corresponding CD4+ T cell activation. Following BD Facs Canto II event acquisition, variations in %CD38, %CD69, Human Leukocyte Antigen -DR (HLA-DR), Programmed cell death protein 1 (PD-1), T-cell immunoglobulin and mucin domain-containing protein 3 (Tim-3), interferon gamma (IFN γ) and interleukin 2 (IL-2) CD4 + T cell expression were evaluated.

RESULTS

Following exposure to SEB, only A. indica demonstrated a concentration-dependent ability to downregulate the levels of CD4 + T cell activation. At the final concentration of 0.500 μg/mL of A. indica, a significant downregulation of CD4 + CD38 + HLA-DR+ expression was observed in HIV negative (p < 0.0001) and both HIV infected groups (P = 0.0313). This plant extract also significantly lowered SEB induced % CD4+ T cell HLADR, PD-1 and Tim-3 levels. PD-1 and CD69 markers were only significantly downmodulated in only the HIV negative ((p = 0.0001 and p = 0.0078 respectively) and viral load< 1000 copies per ml (p = 0.0078) groups.

CONCLUSION

A. indica exhibited the in-vitro immunomodulatory potential to inhibit the continuum of SEB induced CD4+ T-cell activation/ exhaustion without impacting general T-cell specific functions such as cytokine secretion. Additional studies are needed to confirm A. indica as a source of natural products for targeting persistent immune activation and inflammation during ART.

Transcriptional and epigenetic regulation of PD-1 expression

Programmed cell death-1 (PD-1) is a co-inhibitory receptor that plays important roles in regulating T cell immunity and peripheral tolerance. PD-1 signaling prevents T cells from overactivation during acute infections, but it maintains T cell exhaustion during chronic infections. Tumor cells can exploit the PD-1 signaling pathway to evade antitumor immune responses. The PD-1 signaling pathway is also essential for maintaining peripheral tolerance and prevention of autoimmunity. PD-1 expression is strictly and differentially regulated by diverse mechanisms in immune cells. It is activated and repressed by distinct transcription factors in different circumstances. Moreover, epigenetic mechanisms are also involved in regulating PD-1 expression. In this review, we summarize the knowledge of the transcriptional and epigenetic regulation of PD-1 expression during different immune responses.

A Therapeutic Strategy to Combat HIV-1 Latently Infected Cells With a Combination of Latency-Reversing Agents Containing DAG-Lactone PKC Activators

Advances in antiviral therapy have dramatically improved the therapeutic effects on HIV type 1 (HIV-1) infection. However, even with potent combined antiretroviral therapy, HIV-1 latently infected cells cannot be fully eradicated. Latency-reversing agents (LRAs) are considered a potential tool for eliminating such cells; however, recent in vitro and in vivo studies have raised serious concerns regarding the efficacy and safety of the "shock and kill" strategy using LRAs. In the present study, we examined the activity and safety of a panel of protein kinase C (PKC) activators with a diacylglycerol (DAG)-lactone structure that mimics DAG, an endogenous ligand for PKC isozymes. YSE028, a DAG-lactone derivative, reversed HIV-1 latency in vitro when tested using HIV-1 latently infected cells (e.g., ACH2 and J-Lat cells) and primary cells from HIV-1-infected individuals. The activity of YSE028 in reversing HIV-1 latency was synergistically enhanced when combined with JQ1, a bromodomain and extra-terminal inhibitor LRA. DAG-lactone PKC activators also induced caspase-mediated apoptosis, specifically in HIV-1 latently infected cells. In addition, these DAG-lactone PKC activators showed minimal toxicity in vitro and in vivo. These data suggest that DAG-lactone PKC activators may serve as potential candidates for combination therapy against HIV-1 latently infected cells, especially when combined with other LRAs with a different mechanism, to minimize side effects and achieve maximum efficacy in various reservoir cells of the whole body.

Role of NKG2a/c+CD8+ T cells in pathogenic versus non-pathogenic SIV infections

Some viruses have established an equilibrium with their host. African green monkeys (AGM) display persistent high viral replication in the blood and intestine during Simian immunodeficiency virus (SIV) infection but resolve systemic inflammation after acute infection and lack intestinal immune or tissue damage during chronic infection. We show that NKG2_a/c⁺CD8⁺ T cells increase in the blood and intestine of AGM in response to SIVagm infection in contrast to SIVmac infection in macaques, the latter modeling HIV infection. NKG2_a/c⁺CD8⁺ T cells were not expanded in lymph nodes, and CXCR5⁺NKG2_a/c⁺CD8⁺ T cell frequencies further decreased after SIV infection. Genome-wide transcriptome analysis of NKG2_a/c⁺CD8⁺ T cells from AGM revealed the expression of NK cell receptors, and of molecules with cytotoxic effector, gut homing, and immunoregulatory and gut barrier function, including CD73. NKG2_a/c⁺CD8⁺ T cells correlated negatively with IL-23 in the intestine during SIVmac infection. The data suggest a potential regulatory role of NKG2_a/c⁺CD8⁺ T cells in intestinal inflammation during SIV/HIV infections.

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Molecular determination of NKG2a/c⁺CD8⁺ T cells in two species of nonhuman primates

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Tissue distribution of NKG2a/c⁺CD8⁺ T cell is profoundly sculpted by SIV infections

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Intestinal NKG2a/c⁺CD8⁺ T cells correlated negatively with IL-23 in SIV infection

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NKG2a/c⁺CD8⁺ T cells might play a protective gut barrier function in HIV/SIV infection

Immunologic Control of HIV-1: What Have We Learned and Can We Induce It?

PURPOSE OF REVIEW

A large amount of data now exists on the virus-specific immune response associated with spontaneous or induced immunologic control of lentiviruses. This review focuses on how the current understanding of HIV-specific immunity might be leveraged into induction of immunologic control and what further research is needed to accomplish this goal.

RECENT FINDINGS

During chronic infection, the function most robustly associated with immunologic control of HIV-1 is CD8⁺ T cell cytotoxic capacity. This function has proven difficult to restore in HIV-specific CD8⁺ T cells of chronically infected progressors in vitro and in vivo. However, progress has been made in inducing an effective CD8⁺ T cell response prior to lentiviral infection in the macaque model and during acute lentiviral infection in non-human primates. Further study will likely accelerate the ability to induce an effective CD8⁺ T cell response as part of prophylactic or therapeutic strategies.

Probing the Interface of HIV and Inflammaging

PURPOSE OF REVIEW

Systemic inflammation increases as a consequence of aging (inflammaging) and contributes to age-related morbidities. Inflammation in people living with HIV is elevated compared with the general population even after prolonged suppression of viremia with anti-retroviral therapy. Mechanisms that contribute to inflammation during aging and in treated HIV disease are potentially interactive, leading to an exaggerated inflammatory phenotype in people with HIV.

RECENT FINDINGS

Recent studies highlight roles for anti-retroviral therapy, co-infections, immune system alterations, and microbiome perturbations as important contributors to HIV-associated inflammation. These factors likely contribute to increased risk of age-related morbidities in people living with HIV. Understanding mechanisms that exaggerate the inflammaging process in people with HIV may lead to improved intervention strategies, ultimately, extending both lifespan and healthspan.

Phenotypic and Functional Analyses Guiding Combination Immune Checkpoint Immunotherapeutic Strategies in HTLV-1 Infection

Human T-cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) develops in 1–5% of HTLV-1-infected individuals. Previous studies by us and others have shown that the expression of negative immune checkpoint receptors (NCRs) is significantly increased on CD8 T cells in various chronic viral infections and are associated with poor anti-viral immunity. We have previously identified the differential expression of NCRs on CD8 T cells in blood from patients with HAM/TSP and in central nervous system (CNS) tissues of HTLV-1 infected humanized mice and defined the association with neurological complications. In this study, we determined the co-expression patterns of several key NCRs (PD-1, TIGIT, TIM-3, and LAG-3) and their cognate ligands in HTLV-1 infection and assessed how combination strategies targeting these pathways would impact HTLV-1-specific CD8 T-cell effector functions as an approach to reduce CNS disease outcomes. We found that global CD8 T cells from HAM/TSP patients co-express multiple NCRs at significantly higher frequencies than asymptomatic carriers (AC). Moreover, NCR ligands (PVR and PD-LI) on both plasmacytoid and myeloid dendritic cells were also expressed at higher frequencies in HAM/TSP compared to AC. In both AC and HAM/TSP subjects, combination dual PD-L1/TIGIT or triple PD-L1/TIGIT/TIM-3 blockade with monoclonal antibodies resulted in increases in intracellular cytokine expression in CD8 T cells after virus stimulation, particularly CD107a, a marker of degranulation, and TNF-α, a key cytokine that can directly inhibit viral replication. Interestingly, almost all blockade combinations resulted in reduced IL-2+ HTLV-1-specific CD8 T cell frequencies in HAM/TSP subjects, but not in AC. These results define a novel combinatorial NCR immunotherapeutic blockade strategy to reduce HAM/TSP disease burden.

Impact of anti-PD-1 and anti-CTLA-4 on the HIV reservoir in people living with HIV with cancer on antiretroviral therapy: The AIDS Malignancy Consortium-095 study

BACKGROUND

Antibodies to PD-1 and CTLA-4 may perturb HIV persistence during antiretroviral therapy (ART) by reversing HIV-latency and/or boosting HIV-specific immunity leading to clearance of infected cells. We tested this hypothesis in a clinical trial of anti-PD-1 alone or in combination with anti-CTLA-4 in people living with HIV (PLWH) and cancer.

METHODS

This was a substudy of the AIDS Malignancy Consortium-095 Study. ART-suppressed PLWH with advanced malignancies were assigned to nivolumab (anti-PD-1) with or without ipilimumab (anti-CTLA-4). In samples obtained pre-infusion and one and seven days after the first and fourth dose of immune checkpoint blockade (ICB), we quantified cell-associated unspliced (CA-US) HIV-RNA and HIV-DNA. Plasma HIV-RNA was quantified during the first treatment cycle. Quantitative viral outgrowth assay (QVOA) to estimate the frequency of replication-competent HIV was performed before and after ICB for participants with samples available.

RESULTS

Of forty participants, 33 received nivolumab and seven nivolumab plus ipilimumab. Whereas CA-US HIV RNA did not change with nivolumab monotherapy, we detected a median 1.44 fold-increase (IQR 1.16-1.89) after the first dose of nivolumab and ipilimumab combination therapy (P=0.031). There was no decrease in the frequency of cells containing replication-competent HIV, but in the two individuals on combination ICB for whom we had longitudinal QVOA, we detected decreases of 97% and 64% compared to baseline.

CONCLUSION

Anti-PD-1 alone showed no effect on HIV-latency or the latent HIV-reservoir, but the combination of anti-PD-1 and anti-CTL-4 induced a modest increase in CA-US HIV RNA and may potentially eliminate cells containing replication-competent HIV.

An unexpected role for p53 in regulating cancer cell-intrinsic PD-1 by acetylation

Cancer cell-intrinsic programmed cell death protein-1 (PD-1) has emerged as a tumor regulator in an immunity-independent manner, but its precise role in modulating tumor behaviors is complex, and how PD-1 is regulated in cancer cells is largely unknown. Here, we identified PD-1 as a direct target of tumor suppressor p53. Notably, p53 acetylation at K120/164 played a critical role in p53-mediated PD-1 transcription. Acetylated p53 preferentially recruited acetyltransferase cofactors onto PD-1 promoter, selectively facilitating PD-1 transcription by enhancing local chromatin acetylation. Reexpression of PD-1 in cancer cells inhibited tumor growth, whereas depletion of cancer cell-intrinsic PD-1 compromised p53-dependent tumor suppression. Moreover, histone deacetylase inhibitor (HDACi) activated PD-1 in an acetylated p53-dependent manner, supporting a synergistic effect by HDACi and p53 on tumor suppression via stimulating cancer cell-intrinsic PD-1. Our study reveals a mechanism for activating cancer cell-intrinsic PD-1 and indicates that p53-mediated PD-1 activation is critically involved in tumor suppression in an immunity-independent manner.

Epigenetic regulation of T cell adaptive immunity

The conceptualization of adaptive immunity, founded on the observation of immunological memory, has served as the basis for modern vaccination and immunotherapy approaches. This fundamental concept has allowed immunologists to explore mechanisms that enable humoral and cellular lymphocytes to tailor immune response functions to a wide array of environmental insults and remain poised for future pathogenic encounters. Until recently, for T cells it has remained unclear how memory differentiation acquires and sustains a gene expression program that grants a cell with a capacity for a heightened recall response. Recent investigations into this critical question have identified epigenetic programs as a causal molecular mechanism governing T cell subset specification and immunological memory. Here, we outline the studies that have illustrated this concept and posit on how insights into T cell adaptive immunity can be applied to improve upon existing immunotherapies.

Anti-PD-1 and Anti-PD-L1 Monoclonal Antibodies in People Living with HIV and Cancer

PURPOSE OF REVIEW

Immune checkpoint inhibitors targeting the programmed cell death-1 (PD-1) pathway are a class of anti-cancer immunotherapy agents changing treatment paradigms of many cancers that occur at higher rates in people living with HIV (PLWH) than in the general population. However, PLWH have been excluded from most of the initial clinical trials with these agents.

RECENT FINDINGS

Two recent prospective studies of anti-PD-1 agents, along with observational studies and a meta-analysis, have demonstrated acceptable safety in PLWH. Preliminary evidence indicates activity in a range of tumors and across CD4⁺ T cell counts. Safety and preliminary activity data suggest monoclonal antibodies targeting PD-1 or its ligand, PD-L1, are generally appropriate for PLWH and cancers for which there are FDA-approved indications. Ongoing and future trials of anti-PD-1 and anti-PD-L1 therapy alone or in combination for HIV-associated cancers may further improve outcomes for this underserved population.

Dampening antiviral immunity can protect the host

Viral infections are very common, and in most cases, the virus is well controlled and eliminated by the immune system. Nevertheless, in some cases, damage of the host tissue inflicted by the virus itself or by the elicited immune response may result in severe disease courses. Thus, regulatory mechanisms are necessary to control virus‐induced and immune pathology. This ensures immune responses are elicited in a potent but controlled manner. In this review, we will outline how immune regulation may contribute to this process. We focus on regulatory T cells and co‐inhibitory receptors and outline how these two regulatory immune components allow for and may even promote potent but not pathologic immune responses. By enabling a balanced immune response, regulatory mechanisms can thus contribute to pathogen control as well as tissue and host protection.

Effect of the use of Galectin-9 and blockade of TIM-3 receptor in the latent cellular reservoir of HIV-1

Reactivation of latent HIV-1 is a necessary step for the purging of the viral reservoir, although it does not seem to be enough. The stimulation of HIV-1 specific cytotoxic T lymphocytes (CTL) may be just as essential for this purpose. In this study, we aimed to show the effect of galectin-9 (Gal-9), known to revert HIV-1 latency, in combination with the blockade of TIM-3, a natural receptor for Gal-9 and an exhaustion marker. We confirmed the ability of Gal-9 to reactivate latent HIV-1 in Jurkat-LAT-GFP cells, as well as in an IL-7-based cellular model. This reactivation was not mediated via the TIM-3 receptor, but rather by the recognition of the Gal-9 of a specific oligosaccharide pattern of resting memory CD4⁺ T cells' surfaces. The potency of Gal-9 in inducing transcription of latent HIV-1 was equal to or greater than that of other latency-reversing agents (LRA). Furthermore, the combination of Gal-9 with other LRA did not show synergistic effects in the reactivation of the latent virus. To evaluate the impact of TIM-3 inhibition on the CTL-response, different co-culture experiments with CD4⁺T, CD8⁺ T, and NK cells were performed. Our data showed that blocking TIM-3 was associated with control of viral replication in both in vitro and ex vivo models in cells from PLWH on antiretroviral therapy. A joint strategy of the use of Gal-9 to reactivate latent HIV-1 and the inhibition of TIM-3 to enhance the HIV-1 CTL specific-response was associated with control of the replication of the virus that was being reactivated, thus potentially contributing to the elimination of the viral reservoir. Our results place this strategy as a promising approach to be tested in future studies. Reactivation of latent-HIV-1 by Gal-9 and reinvigoration of CD8⁺ T cells by TIM-3 blockade could be used separately or in combination.ImportanceHIV-1 infection is a health problem of enormous importance that still causes significant mortality. Antiretroviral treatment (ART) has demonstrated efficacy in the control of HIV-1 replication, decreasing the morbidity and mortality of the infection, but it cannot eradicate the virus. In our work, we tested a protein, galectin-9 (Gal-9), an HIV-1 latency-reversing agent, using an in vitro cellular model of latency and in cells from people living with HIV-1 (PLWH) on antiretroviral therapy. Our results confirmed the potential role of Gal-9 as a molecule with a potent HIV-1 reactivation capacity. More importantly, using a monoclonal antibody against T cell immunoglobulin and the mucin domain-containing molecule 3 (TIM-3) receptor we were able to enhance the HIV-1 cytotoxic T lymphocytes (CTL) specific response to eliminate the CD4⁺ T cells in which the virus had been reactivated. When used together, i.e., Gal-9 and TIM-3 blockade, control of the replication of HIV-1 was observed, suggesting a decrease in the cellular reservoir.

TCF-1 regulates HIV-specific CD8+ T cell expansion capacity

Although many HIV cure strategies seek to expand HIV-specific CD8+ T cells to control the virus, all are likely to fail if cellular exhaustion is not prevented. A loss in stem-like memory properties (i.e., the ability to proliferate and generate secondary effector cells) is a key feature of exhaustion; little is known, however, about how these properties are regulated in human virus-specific CD8+ T cells. We found that virus-specific CD8+ T cells from humans and nonhuman primates naturally controlling HIV/SIV infection express more of the transcription factor TCF-1 than noncontrollers. HIV-specific CD8+ T cell TCF-1 expression correlated with memory marker expression and expansion capacity and declined with antigenic stimulation. CRISPR-Cas9 editing of TCF-1 in human primary T cells demonstrated a direct role in regulating expansion capacity. Collectively, these data suggest that TCF-1 contributes to the regulation of the stem-like memory property of secondary expansion capacity of HIV-specific CD8+ T cells, and they provide a rationale for exploring the enhancement of this pathway in T cell-based therapeutic strategies for HIV.

A Combination of Anti-PD-L1 Treatment and Therapeutic Vaccination Facilitates Improved Retroviral Clearance via Reactivation of Highly Exhausted T Cells

Despite significant efforts, vaccines are not yet available for every infectious pathogen, and the search for a protective approach to prevent the establishment of chronic infections, i.e., with HIV, continues. Immune checkpoint therapies targeting inhibitory receptors, such as PD-1, have shown impressive results against solid tumors.

PD-1-targeted therapies have shown modest antiviral effects in preclinical models of chronic viral infection. Thus, novel therapy protocols are necessary to enhance T cell immunity and viral control to overcome T cell dysfunction and immunosuppression. Here, we demonstrate that nanoparticle-based therapeutic vaccination improved PD-1-targeted therapy during chronic infection with Friend retrovirus (FV). Prevention of inhibitory signals by blocking PD-L1 in combination with therapeutic vaccination with nanoparticles containing the microbial compound CpG and a CD8⁺ T cell Gag epitope peptide synergistically enhanced functional virus-specific CD8⁺ T cell responses and improved viral clearance. We characterized the CD8⁺ T cell populations that were affected by this combination therapy, demonstrating that new effector cells were generated and that exhausted CD8⁺ T cells were reactivated at the same time. While CD8⁺ T cells with high PD-1 (PD-1^hi) expression turned into a large population of granzyme B-expressing CD8⁺ T cells after combination therapy, CXCR5-expressing follicular cytotoxic CD8⁺ T cells also expanded to a high degree. Thus, our study describes a very efficient approach to enhance virus control and may help us to understand the mechanisms of combination immunotherapy reactivating CD8⁺ T cell immunity. A better understanding of CD8⁺ T cell immunity during combination therapy will be important for developing efficient checkpoint therapies against chronic viral infections and cancer.

Use of pembrolizumab with or without pomalidomide in HIV-associated non-Hodgkin's lymphoma

BACKGROUND

Non-Hodgkin's lymphoma (NHL) is currently the most common malignancy among people living with HIV (PLWH) in the USA. NHL in PLWH is more frequently associated with oncogenic viruses than NHL in immunocompetent individuals and is generally associated with increased PD-1 expression and T cell exhaustion. An effective immune-based second-line approach that is less immunosuppressive than chemotherapy may decrease infection risk, improve immune control of oncogenic viruses, and ultimately allow for better lymphoma control.

METHODS

We conducted a retrospective study of patients with HIV-associated lymphomas treated with pembrolizumab±pomalidomide in the HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute.

RESULTS

We identified 10 patients with stage IV relapsed and/or primary refractory HIV-associated NHL who were treated with pembrolizumab, an immune checkpoint inihibitor, with or without pomalidomide. Five patients had primary effusion lymphoma (PEL): one had germinal center B cell-like (GCB) diffuse large B cell lymphoma (DLBCL); two had non-GCB DLBCL; one had aggressive B cell lymphoma, not otherwise specified; and one had plasmablastic lymphoma. Six patients received pembrolizumab alone at 200 mg intravenously every 3 weeks, three received pembrolizumab 200 mg intravenously every 4 weeks plus pomalidomide 4 mg orally every day for days 1-21 of a 28-day cycle; and one sequentially received pembrolizumab alone and then pomalidomide alone. The response rate was 50% with particular benefit in gammaherpesvirus-associated tumors. The progression-free survival was 4.1 months (95% CI: 1.3 to 12.4) and overall survival was 14.7 months (95% CI: 2.96 to not reached). Three patients with PEL had leptomeningeal disease: one had a complete response and the other two had long-term disease control. There were four immune-related adverse events (irAEs), all CTCAEv5 grade 2-3; three of the four patients were able to continue receiving pembrolizumab. No irAEs occurred in patients receiving the combination of pembrolizumab and pomalidomide.

CONCLUSIONS

Treatment of HIV-associated NHL with pembrolizumab with or without pomalidomide elicited responses in several subtypes of HIV-associated NHL. This approach is worth further study in PLWH and NHL.

Assessment of the Feasibility and Safety of Durvalumab for Treatment of Solid Tumors in Patients With HIV-1 Infection: The Phase 2 DURVAST Study

Importance

Therapies targeting the programmed cell death 1 (PD-1) receptor or its ligand (PD-L1), such as the humanized monoclonal antibody durvalumab, have shown durable clinical responses in several tumor types. However, concerns about the safety and feasibility of PD-1/PD-L1 blockade in HIV-1-infected individuals have led to the exclusion of these patients from clinical trials on cancer immunotherapies.

Objective

To evaluate the feasibility and safety of durvalumab treatment in patients with advanced cancer and virologically controlled HIV-1 infection.

Design, Setting, and Participants

The DURVAST study was a nonrandomized, open-label, phase 2 clinical trial in patients with any solid tumor type in which anti-PD-1 or anti-PD-L1 antibodies have approved indications or for which there are data of antitumoral activity with no other available curative therapy. All patients had basal undetectable plasma viremia while undergoing combination antiretroviral therapy.

Interventions

Treatment consisted of intravenous infusion of durvalumab (1500 mg every 4 weeks) until disease progression or unacceptable toxic effects.

Main Outcomes and Measures

Adverse events were graded with the use of the National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.03. Tumor response was evaluated using the Response Evaluation Criteria in Solid Tumors version 1.1.

Results

A total of 20 HIV-1-infected patients with advanced cancer were enrolled; 16 (80%) were male, the median (range) age was 54 (30-73) years, and 12 (60%) had progressed with previous cancer treatment lines. A median (range) of 4 (1-16) cycles of durvalumab were administered. Drug-related adverse events were observed in 50% of patients, and all were grade 1 and 2 (mainly diarrhea, asthenia, and arthromyalgia). Four of 16 response-evaluable patients (25%) had a partial response. Five patients (31%) had stable disease, including 4 with durable stable disease (disease control rate of 50%). CD4+ and CD8+ T-cell counts and plasma HIV-1 viremia remained stable throughout the study.

Conclusions and Relevance

Durvalumab treatment was feasible and safe in HIV-1-infected patients with cancer receiving combination antiretroviral therapy. HIV-1-infected patients on suppressive antiretroviral therapy with advanced cancer should have access to cancer immunotherapy treatments.

Trial Registration

ClinicalTrials.gov Identifier: NCT03094286.

CD32+CD4+ memory T cells are enriched for total HIV-1 DNA in tissues from humanized mice

CD32 has raised conflicting results as a putative marker of the HIV-1 reservoir. We measured CD32 expression in tissues from viremic and virally suppressed humanized mice treated relatively early or late after HIV-1 infection with combined antiretroviral therapy. CD32 was expressed in a small fraction of the memory CD4+ T-cell subsets from different tissues in viremic and aviremic mice, regardless of treatment initiation time. CD32+ memory CD4+ T cells were enriched in cell-associated (CA) HIV-1 DNA but not in CA HIV-1 RNA as compared to the CD32-CD4+ fraction. Using multidimensional reduction analysis, several memory CD4+CD32+ T-cell clusters were identified expressing HLA-DR, TIGIT, or PD-1. Importantly, although tissue-resident CD32+CD4+ memory cells were enriched with translation-competent reservoirs, most of it was detected in memory CD32-CD4+ T cells. Our findings support that CD32 labels highly activated/exhausted memory CD4+ T-cell subsets that contain only a small proportion of the translation-competent reservoir.

Extensive proteomic and transcriptomic changes quench the TCR/CD3 activation signal of latently HIV-1 infected T cells

The biomolecular mechanisms controlling latent HIV-1 infection, despite their importance for the development of a cure for HIV-1 infection, are only partially understood. For example, ex vivo studies have recently shown that T cell activation only triggered HIV-1 reactivation in a fraction of the latently infected CD4+ T cell reservoir, but the molecular biology of this phenomenon is unclear. We demonstrate that HIV-1 infection of primary T cells and T cell lines indeed generates a substantial amount of T cell receptor (TCR)/CD3 activation-inert latently infected T cells. RNA-level analysis identified extensive transcriptomic differences between uninfected, TCR/CD3 activation-responsive and -inert T cells, but did not reveal a gene expression signature that could functionally explain TCR/CD3 signaling inertness. Network analysis suggested a largely stochastic nature of these gene expression changes (transcriptomic noise), raising the possibility that widespread gene dysregulation could provide a reactivation threshold by impairing overall signal transduction efficacy. Indeed, compounds that are known to induce genetic noise, such as HDAC inhibitors impeded the ability of TCR/CD3 activation to trigger HIV-1 reactivation. Unlike for transcriptomic data, pathway enrichment analysis based on phospho-proteomic data directly identified an altered TCR signaling motif. Network analysis of this data set identified drug targets that would promote TCR/CD3-mediated HIV-1 reactivation in the fraction of otherwise TCR/CD3-reactivation inert latently HIV-1 infected T cells, regardless of whether the latency models were based on T cell lines or primary T cells. The data emphasize that latent HIV-1 infection is largely the result of extensive, stable biomolecular changes to the signaling network of the host T cells harboring latent HIV-1 infection events. In extension, the data imply that therapeutic restoration of host cell responsiveness prior to the use of any activating stimulus will likely have to be an element of future HIV-1 cure therapies.

A curative therapy for HIV-1 infection will at least require the eradication of a small pool of CD4+ helper T cells in which the virus can persist in an inactive, latent state, even after years of successful antiretroviral therapy. It has been assumed that activation of these viral reservoir T cells will also reactivate the latent virus, which is a prerequisite for the destruction of these cells. Remarkably, this is not always the case and following application of even the most potent stimuli that activate normal T cells through their T cell receptor, a large portion of the latent virus pool remains in a dormant state. Herein we demonstrate that a large part of latent HIV-1 infection events reside in T cells that have been rendered activation inert. We provide a systemwide, biomolecular description of the changes that render latently HIV-1 infected T cells activation inert and using this description, devise pharmacologic interference strategies that render initially activation inert T cells responsive to stimulation. This in turn allows for efficient triggering of HIV-1 reactivation in a large part of the otherwise unresponsive latently HIV-1 infected T cell reservoir.

HIV DNA reservoir and elevated PD-1 expression of CD4 T-cell subsets particularly persist in the terminal ileum of HIV-positive patients despite cART

OBJECTIVES

Despite its importance as an HIV anatomic sanctuary, little is known about the characteristics of the HIV reservoir in the terminal ileum (TI). In blood, the immune checkpoint inhibitor programmed-death-1 (PD-1) has been linked to the HIV reservoir and T-cell immune dysfunction. We thus evaluated PD-1 expression and cell-associated HIV DNA in memory CD4 T-cell subsets from TI, peripheral blood (PB) and rectum (RE) of untreated and treated HIV-positive patients to identify associations between PD-1 and HIV reservoir in other sites.

METHODS

Using mononuclear cells from PB, TI and RE of untreated HIV-positive (N = 6), treated (n = 18) HIV-positive and uninfected individuals (n = 16), we identified and sorted distinct memory CD4 T-cell subsets by flow cytometry, quantified their cell-associated HIV DNA using quantitative PCR and assessed PD-1 expression levels using geometric mean fluorescence intensity. Combined HIV-1 RNA in situ hybridization and immunohistochemistry was performed on ileal biopsy sections.

RESULTS

Combined antiretroviral therapy (cART)-treated patients with undetectable HIV RNA and significantly lower levels of HIV DNA in PB showed particularly high PD-1 expression in PB and TI, and high HIV DNA levels in TI, irrespective of clinical characteristics. By contrast, in treatment-naïve patients HIV DNA levels in memory CD4 T-cell subsets were high in PB and TI.

CONCLUSION

Elevated PD-1 expression on memory CD4 T-cells in PB and TI despite treatment points to continuous immune dysfunction and underlines the importance of evaluating immunotherapy in reversing HIV latency and T-cell reconstitution. As HIV DNA particularly persists in TI despite cART, investigating samples from TI is crucial in understanding HIV immunopathogenesis.

Oxidative Stress Induces Mitochondrial Compromise in CD4 T Cells From Chronically HCV-Infected Individuals

We have previously shown that chronic Hepatitis C virus (HCV) infection can induce DNA damage and immune dysfunctions with excessive oxidative stress in T cells. Furthermore, evidence suggests that HCV contributes to increased susceptibility to metabolic disorders. However, the underlying mechanisms by which HCV infection impairs cellular metabolism in CD4 T cells remain unclear. In this study, we evaluated mitochondrial mass and intracellular and mitochondrial reactive oxygen species (ROS) production by flow cytometry, mitochondrial DNA (mtDNA) content by real-time qPCR, cellular respiration by seahorse analyzer, and dysregulated mitochondrial-localized proteins by Liquid Chromatography-Mass Spectrometry (LC-MS) in CD4 T cells from chronic HCV-infected individuals and health subjects. Mitochondrial mass was decreased while intracellular and mitochondrial ROS were increased, expressions of master mitochondrial regulators peroxisome proliferator-activated receptor 1 alpha (PGC-1α) and mitochondrial transcription factor A (mtTFA) were down-regulated, and oxidative stress was increased while mitochondrial DNA copy numbers were reduced. Importantly, CRISPR/Cas9-mediated knockdown of mtTFA impaired cellular respiration and reduced mtDNA copy number. Furthermore, proteins responsible for mediating oxidative stress, apoptosis, and mtDNA maintenance were significantly altered in HCV-CD4 T cells. These results indicate that mitochondrial functions are compromised in HCV-CD4 T cells, likely via the deregulation of several mitochondrial regulatory proteins.

Effects of Brief Adjunctive Metformin Therapy in Virologically Suppressed HIV-Infected Adults on Polyfunctional HIV-Specific CD8 T Cell Responses to PD-L1 Blockade

Targeting inhibitory immune checkpoint receptor pathways has shown remarkable success in improving anticancer T cell responses for the elimination of tumors. Such immunotherapeutic strategies are being pursued for HIV remission. Metformin has shown favorable clinical outcomes in enhancing the efficacy of programmed cell death-1 (PD-1) blockade and restoring antitumor T cell immunity. Furthermore, monocytes are known to be a strong predictor of progression-free survival in response to anti-PD-1 immunotherapy. In a single-arm clinical trial, we evaluated the immunological effects over an 8-week course of metformin therapy in seven euglycemic, virally suppressed HIV-infected participants on combination antiretroviral therapy (cART). We assessed changes in peripheral HIV-Gag-specific T cell responses to immune checkpoint blockade (ICB) with anti-PD-L1 and anti-T cell immunoreceptor with immunoglobulin and ITIM domain (TIGIT) monoclonal antibodies (mAbs) and changes in CD8 T cell and monocyte subsets using flow cytometry. Study participants were all male, 71% (5/7) Caucasian, with a median age of 61 years, CD4 count of 739 cells/μL, and plasma HIV RNA of <50 copies/mL on stable cART for >1 year. Ex vivo polyfunctional HIV-Gag-specific CD8 T cell responses to anti-PD-L1 mAb significantly improved (p < .05) over the 8-week course of metformin therapy. Moreover, frequencies of both intermediate (CD14⁺CD16⁺; r = 0.89, p = .01) and nonclassical (CD14^lowCD16⁺; r = 0.92, p = .01) monocytes at entry were predictive of the magnitude of the anti-HIV CD8 T cell responses to PD-L1 blockade. Collectively, these findings highlight that 8-week course of metformin increases the polyfunctionality of CD8 T cells and that baseline monocyte subset frequencies may be a potential determinant of PD-L1 blockade efficacy. These data provide valuable information for HIV remission trials that utilize ICB strategies to enhance anti-HIV CD8 T cell immunity.

TCR Transgenic Mice: A Valuable Tool for Studying Viral Immunopathogenesis Mechanisms

Viral infectious diseases are a significant burden on public health and the global economy, and new viral threats emerge continuously. Since CD4⁺ and CD8⁺ T cell responses are essential to eliminating viruses, it is important to understand the underlying mechanisms of anti-viral T cell-mediated immunopathogenesis during viral infections. Remarkable progress in transgenic (Tg) techniques has enabled scientists to more readily understand the mechanisms of viral pathogenesis. T cell receptor (TCR) Tg mice are extremely useful in studying T cell-mediated immune responses because the majority of T cells in these mice express specific TCRs for partner antigens. In this review, we discuss the important studies utilizing TCR Tg mice to unveil underlying mechanisms of T cell-mediated immunopathogenesis during viral infections.

Prolonged administration of maraviroc reactivates latent HIV in vivo but it does not prevent antiretroviral-free viral rebound

Human immunodeficiency virus (HIV) remains incurable due to latent viral reservoirs established in non-activated CD4 T cells that cannot be eliminated via antiretroviral therapy. Current efforts to cure HIV are focused on identifying drugs that will induce viral gene expression in latently infected cells, commonly known as latency reversing agents (LRAs). Some drugs have been shown to reactivate latent HIV but do not cause a reduction in reservoir size. Therefore, finding new LRAs or new combinations or increasing the round of stimulations is needed to cure HIV. However, the effects of these drugs on viral rebound after prolonged treatment have not been evaluated. In a previous clinical trial, antiretroviral therapy intensification with maraviroc for 48 weeks caused an increase in residual viremia and episomal two LTR-DNA circles suggesting that maraviroc could reactivate latent HIV. We amended the initial clinical trial to explore additional virologic parameters in stored samples and to evaluate the time to viral rebound during analytical treatment interruption in three patients. Maraviroc induced an increase in cell-associated HIV RNA during the administration of the drug. However, there was a rapid rebound of viremia after antiretroviral therapy discontinuation. HIV-specific T cell response was slightly enhanced. These results show that maraviroc can reactivate latent HIV in vivo but further studies are required to efficiently reduce the reservoir size.

CD57+ Memory T Cells Proliferate In Vivo

A central paradigm in the field of lymphocyte biology asserts that replicatively senescent memory T cells express the carbohydrate epitope CD57. These cells nonetheless accumulate with age and expand numerically in response to persistent antigenic stimulation. Here, we use in vivo deuterium labeling and ex vivo analyses of telomere length, telomerase activity, and intracellular expression of the cell-cycle marker Ki67 to distinguish between two non-exclusive scenarios: (1) CD57+ memory T cells do not proliferate and instead arise via phenotypic transition from the CD57- memory T cell pool; and/or (2) CD57+ memory T cells self-renew via intracompartmental proliferation. Our results provide compelling evidence in favor of the latter scenario and further suggest in conjunction with mathematical modeling that self-renewal is by far the most abundant source of newly generated CD57+ memory T cells. Immunological memory therefore appears to be intrinsically sustainable among highly differentiated subsets of T cells that express CD57.

Sharing CD4+ T Cell Loss: When COVID-19 and HIV Collide on Immune System

COVID-19 is a distinctive infection characterized by elevated inter-human transmission and presenting from absence of symptoms to severe cytokine storm that can lead to dismal prognosis. Like for HIV, lymphopenia and drastic reduction of CD4+ T cell counts in COVID-19 patients have been linked with poor clinical outcome. As CD4+ T cells play a critical role in orchestrating responses against viral infections, important lessons can be drawn by comparing T cell response in COVID-19 and in HIV infection and by studying HIV-infected patients who became infected by SARS-CoV-2. We critically reviewed host characteristics and hyper-inflammatory response in these two viral infections to have a better insight on the large difference in clinical outcome in persons being infected by SARS-CoV-2. The better understanding of mechanism of T cell dysfunction will contribute to the development of targeted therapy against severe COVID-19 and will help to rationally design vaccine involving T cell response for the long-term control of viral infection.

Peculiar Phenotypic and Cytotoxic Features of Pulmonary Mucosal CD8 T Cells in People Living with HIV Receiving Long-Term Antiretroviral Therapy

People living with HIV have high burdens of chronic lung disease, lung cancers, and pulmonary infections despite antiretroviral therapy (ART). The rates of tobacco smoking by people living with HIV vastly exceed that of the general population. Furthermore, we showed that HIV can persist within the lung mucosa despite long-term ART. As CD8 T cell cytotoxicity is pivotal for controlling viral infections and eliminating defective cells, we explored the phenotypic and functional features of pulmonary versus peripheral blood CD8 T cells in ART-treated HIV⁺ and uninfected controls. Bronchoalveolar lavage fluid and matched blood were obtained from asymptomatic ART-treated HIV⁺ smokers (n = 11) and nonsmokers (n = 15) and uninfected smokers (n = 7) and nonsmokers (n = 10). CD8 T cell subsets and phenotypes were assessed by flow cytometry. Perforin/granzyme B content, degranulation (CD107a expression), and cytotoxicity against autologous Gag peptide-pulsed CD4 T cells (Annexin V⁺) following in vitro stimulation were assessed. In all groups, pulmonary CD8 T cells were enriched in effector memory subsets compared with blood and displayed higher levels of activation (HLA-DR⁺) and exhaustion (PD1⁺) markers. Significant reductions in proportions of senescent pulmonary CD28^-CD57⁺ CD8 T cells were observed only in HIV⁺ smokers. Pulmonary CD8 T cells showed lower perforin expression ex vivo compared with blood CD8 T cells, with reduced granzyme B expression only in HIV⁺ nonsmokers. Bronchoalveolar lavage CD8 T cells showed significantly less in vitro degranulation and CD4 killing capacity than blood CD8 T cells. Therefore, pulmonary mucosal CD8 T cells are more differentiated, activated, and exhausted, with reduced killing capacity in vitro than blood CD8 T cells, potentially contributing to a suboptimal anti-HIV immune response within the lungs.

An atlas of immune cell exhaustion in HIV-infected individuals revealed by single-cell transcriptomics

Chronic infection with human immunodeficiency virus (HIV) can cause progressive loss of immune cell function, or exhaustion, which impairs control of virus replication. However, little is known about the development and maintenance, as well as heterogeneity of immune cell exhaustion. Here, we investigated the effects of HIV infection on immune cell exhaustion at the transcriptomic level by analyzing single-cell RNA sequencing of peripheral blood mononuclear cells from four healthy subjects (37,847 cells) and six HIV-infected donors (28,610 cells). We identified nine immune cell clusters and eight T cell subclusters, and three of these (exhausted CD4+ and CD8+ T cells and interferon-responsive CD8+ T cells) were detected only in samples from HIV-infected donors. An inhibitory receptor KLRG1 was identified in a HIV-1 specific exhausted CD8+ T cell population expressing KLRG1, TIGIT, and T-betdimEomeshi markers. Ex-vivo antibody blockade of KLRG1 restored the function of HIV-specific exhausted CD8+ T cells demonstrating the contribution of KLRG1+ population to T cell exhaustion and providing an immunotherapy target to treat HIV chronic infection. These data provide a comprehensive analysis of gene signatures associated with immune cell exhaustion during HIV infection, which could be useful in understanding exhaustion mechanisms and developing new cure therapies.

Mesenchymal stem cells protect against malaria pathogenesis by reprogramming erythropoiesis in the bone marrow

Malaria remains a major public health problem worldwide. The immune mechanisms that mediate protection against malaria are still unclear. Previously, we reported that mesenchymal stem cells (MSCs) play a critical role in host protection against malaria by altering the dynamic balance of T regulatory cells and effector T cells producing inflammatory cytokines. Here, we report that MSCs reprogram haematopoiesis in primary (bone marrow) and secondary (spleen) lymphoid organs to provide host protection against malaria. Adoptive transfer of MSCs from malaria-infected mice to naïve recipient mice that were subsequently infected with malaria parasites dramatically accelerated the formation of colony-forming units-erythroid cells in the bone marrow. Adoptively transferred MSCs also induced expression of the key erythroid cell differentiation factor GATA-1 in the spleen of recipient animals. Interestingly, we further observed a subtle increase in the CD34⁺ hematopoietic stem and progenitor cells in lymphoid organs, including spleen and lymph nodes. Infusion of MSCs also enhanced T cell proliferation, resulting in increased numbers of both CD4⁺ and CD8⁺ T cells in the spleen. MSCs also inhibited the induction of the negative co-stimulatory receptor programmed death-1 by T cells in recipient animals upon infection with malaria parasites. Taken together, our findings suggest that MSCs play a critical role in host protection against malaria infection by modulating erythropoiesis and lymphopoiesis.

Antigenic Restimulation of Virus-Specific Memory CD8+ T Cells Requires Days of Lytic Protein Accumulation for Maximal Cytotoxic Capacity

In various infections or vaccinations of mice or humans, reports of the persistence and the requirements for restimulation of the cytotoxic mediators granzyme B (GrB) and perforin (PRF) in CD8+ T cells have yielded disparate results. In this study, we examined the kinetics of PRF and GrB mRNA and protein expression after stimulation and associated changes in cytotoxic capacity in virus-specific memory cells in detail. In patients with controlled HIV or cleared respiratory syncytial virus (RSV) or influenza virus infections, all virus-specific CD8+ T cells expressed low PRF levels without restimulation. Following stimulation, they displayed similarly delayed kinetics for lytic protein expression, with significant increases occurring by days 1 to 3 before peaking on days 4 to 6. These increases were strongly correlated with, but were not dependent upon, proliferation. Incremental changes in PRF and GrB percent expression and mean fluorescence intensity (MFI) were highly correlated with increases in HIV-specific cytotoxicity. mRNA levels in HIV-specific CD8+ T-cells exhibited delayed kinetics after stimulation as with protein expression, peaking on day 5. In contrast to GrB, PRF mRNA transcripts were little changed over 5 days of stimulation (94-fold versus 2.8-fold, respectively), consistent with posttranscriptional regulation. Changes in expression of some microRNAs, including miR-17, miR-150, and miR-155, suggested that microRNAs might play a significant role in regulation of PRF expression. Therefore, under conditions of extremely low or absent antigen levels, memory virus-specific CD8+ T cells require prolonged stimulation over days to achieve maximal lytic protein expression and cytotoxic capacity.IMPORTANCE Antigen-specific CD8+ T cells play a major role in controlling most virus infections, primarily by perforin (PRF)- and granzyme B (GrB)-mediated apoptosis. There is considerable controversy regarding whether PRF is constitutively expressed, rapidly increased similarly to a cytokine, or delayed in its expression with more prolonged stimulation in virus-specific memory CD8+ T cells. In this study, the degree of cytotoxic capacity of virus-specific memory CD8+ T cells was directly proportional to the content of lytic molecules, which required antigenic stimulation over several days for maximal levels. This appeared to be modulated by increases in GrB transcription and microRNA-mediated posttranscriptional regulation of PRF expression. Clarifying the requirements for maximal cytotoxic capacity is critical to understanding how viral clearance might be mediated by memory cells and what functions should be induced by vaccines and immunotherapies.

Depletion and activation of mucosal CD4 T cells in HIV infected women with HPV-associated lesions of the cervix uteri

BACKGROUND

The burden of HPV-associated premalignant and malignant cervical lesions remains high in HIV+ women even under ART treatment. In order to identify possible underlying pathophysiologic mechanisms, we studied activation and HIV co-receptor expression in cervical T-cell populations in relation to HIV, HPV and cervical lesion status.

METHODS

Cervical cytobrush (n = 468: 253 HIV- and 215 HIV+; 71% on ART) and blood (in a subset of 39 women) was collected from women in Mbeya, Tanzania. Clinical data on HIV and HPV infection, as well as ART status was collected. T cell populations were characterized using multiparametric flow cytometry-based on their expression of markers for cellular activation (HLA-DR), and memory (CD45RO), as well as HIV co-receptors (CCR5, α4β7).

RESULTS

Cervical and blood T cells differed significantly, with higher frequencies of T cells expressing CD45RO, as well as the HIV co-receptors CCR5 and α4β7 in the cervical mucosa. The skewed CD4/CD8 T cell ratio in blood of HIV+ women was mirrored in the cervical mucosa and HPV co-infection was linked to lower levels of mucosal CD4 T cells in HIV+ women (%median: 22 vs 32; p = 0.04). In addition, HIV and HPV infection, and especially HPV-associated cervical lesions were linked to significantly higher frequencies of HLA-DR+ CD4 and CD8 T cells (p-values < 0.05). Interestingly, HPV infection did not significantly alter frequencies of CCR5+ or α4β7+ CD4 T cells.

CONCLUSION

The increased proportion of activated cervical T cells associated with HPV and HIV infection, as well as HPV-associated lesions, together with the HIV-induced depletion of cervical CD4 T cells, may increase the risk for HPV infection, associated premalignant lesions and cancer in HIV+ women. Further, high levels of activated CD4 T cells associated with HPV and HPV-associated lesions could contribute to a higher susceptibility to HIV in HPV infected women.

Combination rhIL-15 and Anti-PD-L1 (Avelumab) Enhances HIVGag-Specific CD8 T-Cell Function

In chronic HIV infection, virus-specific cytotoxic CD8 T cells showed expression of checkpoint receptors and impaired function. Therefore, restoration of CD8 T-cell function is critical in cure strategies. Here, we show that in vitro blockade of programmed cell death ligand 1 (PD-L1) by an anti-PD-L1 antibody (avelumab) in combination with recombinant human interleukin-15 (rhIL-15) synergistically enhanced cytokine secretion by proliferating HIVGag-specific CD8 T cells. In addition, these CD8 T cells have a CXCR3+PD1-/low phenotype, suggesting a potential to traffic into peripheral tissues. In vitro, proliferating CD8 T cells express PD-L1 suggesting that anti-PD-L1 treatment also targets virus-specific CD8 T cells. Together, these data indicate that rhIL-15/avelumab combination therapy could be a useful strategy to enhance CD8 T-cell function in cure strategies.