rhIL-7-hyFc and hIL-2/TCB2c combination promotes an immune-stimulatory tumor microenvironment that improves antitumor efficacy of checkpoint inhibitors.

BACKGROUND: Recombinant human interleukin (rhIL)-7-hyFc (efineptakin alfa; NT-I7) is a potent T-cell amplifier, with two IL-7 molecules fused to IgD/IgG4 elements. rhIL-7-hyFc promotes extensive infiltration of CD8+ T cells into the tumor, concurrently increasing the numbers of intratumoral PD-1+CD8+ T cells. The hIL-2/TCB2 complex (SLC-3010) inhibits tumor growth by preferential activation of CD122 (IL-2Rß)high CD8+ T cells and natural killer cells, over regulatory T cells (Tregs). We investigated the underlying mechanisms of rhIL-7-hyFc and hIL-2/TCB2c antitumor activity and the potential synergistic efficacy, specifically focusing on tumor-specific CD8+ cells within the tumor and the tumor-draining lymph nodes (tdLN). METHODS: MC38 and CT26 tumor-bearing mice were administered with 10 mg/kg rhIL-7-hyFc intramuscularly and 0.9 mg/kg hIL-2/TCB2c intravenously. Anti-PD-1 monoclonal antibody was administered intraperitoneally three times at 3-day intervals at a dose of 5 mg/kg. Tumor volume was measured to assess efficacy. To compare the composition of immune cells between each monotherapy and the combination therapy, we analyzed tumors and tdLNs by flow cytometry. RESULTS: Our data demonstrate that the combination of rhIL-7-hyFc and hIL-2/TCB2c increases efficacy and generates an immune-stimulatory tumor microenvironment (TME). The TME is characterized by an increased infiltration of tumor-specific CD8+ T cells, and a decreased frequency of CD39highTIM-3+ Treg cells. Most importantly, rhIL-7-hyFc increases infiltration of a CD62L+Ly108+ early progenitor population of exhausted CD8+ T cells (TPEX), which may retain long-term proliferation capacity and replenish functional effector CD8+ T cells. hIL-2/TCB2c induces differentiation of CD62L+Ly108+ TPEX rapidly into CD101+ terminally differentiated subsets (terminally exhausted T cell (TEX term)). Our study also demonstrates that rhIL-7-hyFc significantly enhances the proliferation rate of TPEX in the tdLNs, positively correlating with their abundance within the tumor. Moreover, rhIL-7-hyFc and hIL-2/TCB2c can overcome the limited therapeutic effectiveness of PD-1 blockade, culminating in the complete regression of tumors. CONCLUSIONS: rhIL-7-hyFc can expand and maintain the progenitor pool of exhausted CD8+ T cells, whereas hIL-2/TCB2c promotes their differentiation into TEX term. Together, this induces an immune-stimulatory TME that improves the efficacy of checkpoint blockade.

IL-2 produced by HBV-specific T cells as a biomarker of viral control and predictor of response to PD-1 therapy across clinical phases of chronic hepatitis B.

BACKGROUND: There are no immunological biomarkers that predict control of chronic hepatitis B (CHB). The lack of immune biomarkers raises concerns for therapies targeting PD-1/PD-L1 because they have the potential for immune-related adverse events. Defining specific immune functions associated with control of HBV replication could identify patients likely to respond to anti-PD-1/PD-L1 therapies and achieve a durable functional cure. METHODS: We enrolled immunotolerant, HBeAg+ immune-active (IA+), HBeAg- immune-active (IA-), inactive carriers, and functionally cured patients to test ex vivo PD-1 blockade on HBV-specific T cell functionality. Peripheral blood mononuclear cells were stimulated with overlapping peptides covering HBV proteins +/-α-PD-1 blockade. Functional T cells were measured using a 2-color FluoroSpot assay for interferon-γ and IL-2. Ex vivo functional restoration was compared to the interferon response capacity assay, which predicts overall survival in cancer patients receiving checkpoint inhibitors. RESULTS: Ex vivo interferon-γ+ responses did not differ across clinical phases. IL-2+ responses were significantly higher in patients with better viral control and preferentially restored with PD-1 blockade. Inactive carrier patients displayed the greatest increase in IL-2 production, which was dominated by CD4 T cell and response to the HBcAg. The interferon response capacity assay significantly correlated with the degree of HBV-specific T cell restoration. CONCLUSIONS: IL-2 production was associated with better HBV control and superior to interferon-γ as a marker of T cell restoration following ex vivo PD-1 blockade. Our study suggests that responsiveness to ex vivo PD-1 blockade, or the interferon response capacity assay, may support stratification for α-PD-1 therapies.

The Role of Interleukin-7 in the Formation of Tertiary Lymphoid Structures and Their Prognostic Value in Gastrointestinal Cancers.

Immunotherapies for the treatment of solid tumors continue to develop in preclinical and clinical research settings. Unfortunately, for many patients the tumor fails to respond or becomes resistant to therapies such as checkpoint inhibitors (CPIs) targeting programmed cell death protein-1 (PD-1), programmed death-ligand 1 (PD-L1), and cytotoxic T lymphocyte antigen-4 (CTLA-4). In many cancers, failed response to CPIs can be attributed to poor T cell infiltration, dominant immunosuppression, and exhausted immune responses. In gastrointestinal (GI) cancers T cell infiltration can be dismal, with several reports finding that CD8+ T cells compose less than 2% of all cells within the tumor. Organized aggregates of lymphocytes, antigen-presenting cells, and vessels, together termed tertiary lymphoid structures (TLSs), are hypothesized to be a major source of T cells within solid tumors. The intratumoral formation of these organized immune centers appears to rely on intricate cytokine and chemokine signaling to heterogeneous cell populations such as B and T cells, innate lymphoid cells, fibroblasts, and dendritic cells. In GI cancers, the presence and density of TLSs provide prognostic value for predicting outcome and survival. Further, TLS presence and density associates with favorable responses to CPIs in many cancers. This review highlights the prognostic value of TLSs in GI cancers, the role of the homeostatic cytokine interleukin-7 (IL-7) in TLS formation, and the induction of TLSs in solid tumors by novel therapeutics.

Advancements of Common Gamma-Chain Family Cytokines in Cancer Immunotherapy.

The approval of immunotherapies such as checkpoint inhibitors (CPIs), adoptive cell therapies and cancer vaccines has revolutionized the way cancer treatment is approached. While immunotherapies have improved clinical outcome in a variety of tumor types, some cancers have proven harder to combat using single agents, underscoring the need for multi-targeted immunotherapy approaches. Efficacy of CPIs and cancer vaccines requires patients to have a competent immune system with adequate cell numbers while the efficacy of adoptive cellular therapy is limited by the expansion and persistence of cells after infusion. A promising strategy to overcome these challenges is combination treatment with common gamma-chain cytokines. Gamma-chain cytokines play a critical role in the survival, proliferation, differentiation and function of multiple immune cell types, including CD8 T-cells and NK cells, which are at the center of the anti-tumor response. While the short half-life of recombinant cytokines initially limited their application in the clinic, advancements in protein engineering have led to the development of several next-generation drug candidates with dramatically increased half-life and bioactivity. When combining these cytokines with other immunotherapies, strong evidence of synergy has been observed in preclinical and clinical cancer settings. This promising data has led to the initiation of 70 ongoing clinical trials including IL-2, IL-7, IL-15 and IL-21. This review summarizes the recent advancements of common gamma-chain cytokines and their potential as a cancer immunotherapy.

Long-Acting Recombinant Human Interleukin-7, NT-I7, Increases Cytotoxic CD8 T Cells and Enhances Survival in Mouse Glioma Models.

PURPOSE: Patients with glioblastoma (GBM) are treated with radiotherapy (RT) and temozolomide (TMZ). These treatments may cause prolonged systemic lymphopenia, which itself is associated with poor outcomes. NT-I7 is a long-acting IL7 that expands CD4 and CD8 T-cell numbers in humans and mice. We tested whether NT-I7 prevents systemic lymphopenia and improves survival in mouse models of GBM. EXPERIMENTAL DESIGN: C57BL/6 mice bearing intracranial tumors (GL261 or CT2A) were treated with RT (1.8 Gy/day × 5 days), TMZ (33 mg/kg/day × 5 days), and/or NT-I7 (10 mg/kg on the final day of RT). We followed the mice for survival while serially analyzing levels of circulating T lymphocytes. We assessed regulatory T cells (Treg) and cytotoxic T lymphocytes in the tumor microenvironment, cervical lymph nodes, spleen, and thymus, and hematopoietic stem and progenitor cells in the bone marrow. RESULTS: GBM tumor-bearing mice treated with RT+NT-I7 increased T lymphocytes in the lymph nodes, thymus, and spleen, enhanced IFNγ production, and decreased Tregs in the tumor which was associated with a significant increase in survival. NT-I7 also enhanced central memory and effector memory CD8 T cells in lymphoid organs and tumor. Depleting CD8 T cells abrogated the effects of NT-I7. Furthermore, NT-I7 treatment decreased progenitor cells in the bone marrow. CONCLUSIONS: In orthotopic glioma-bearing mice, NT-I7 mitigates RT-related lymphopenia, increases cytotoxic CD8 T lymphocytes systemically and in the tumor, and improves survival. A phase I/II trial to evaluate NT-I7 in patients with high-grade gliomas is ongoing (NCT03687957).

Functional Exhaustion of HBV-Specific CD8 T Cells Impedes PD-L1 Blockade Efficacy in Chronic HBV Infection.

Background: A functional cure for chronic HBV could be achieved by boosting HBV-specific immunity. In vitro studies show that immunotherapy could be an effective strategy. However, these studies include strategies to enrich HBV-specific CD8 T cells, which could alter the expression of the anti-PD-1/anti-PD-L1 antibody targets. Our aim was to determine the efficacy of PD-L1 blockade ex vivo. Methods: HBV-specific CD8 T cells were characterized ex vivo by flow cytometry for the simultaneous analysis of six immune populations and 14 activating and inhibitory receptors. Ex vivo functionality was quantified by ELISpot and by combining peptide pool stimulation, dextramers and intracellular flow cytometry staining. Results: The functionality of HBV-specific CD8 T cells is associated with a higher frequency of cells with low exhaustion phenotype (LAG3-TIM3-PD-1+), independently of the clinical parameters. The accumulation of HBV-specific CD8 T cells with a functionally exhausted phenotype (LAG3+TIM3+PD-1+) is associated with lack of ex vivo functionality. PD-L1 blockade enhanced the HBV-specific CD8 T cell response only in patients with lower exhaustion levels, while response to PD-L1 blockade was abrogated in patients with higher frequencies of exhausted HBV-specific CD8 T cells. Conclusion: Higher levels of functionally exhausted HBV-specific CD8 T cells are associated with a lack of response that cannot be restored by blocking the PD-1:PD-L1 axis. This suggests that the clinical effectiveness of blocking the PD-1:PD-L1 axis as a monotherapy may be restricted. Combination strategies, potentially including the combination of anti-LAG-3 with other anti-iR antibodies, will likely be required to elicit a functional cure for patients with high levels of functionally exhausted HBV-specific CD8 T cells.

Immunogenomic profiling and pathological response results from a clinical trial of docetaxel and carboplatin in triple-negative breast cancer.

PURPOSE: Patients with triple-negative breast cancer (TNBC) who do not achieve pathological complete response (pCR) following neoadjuvant chemotherapy have a high risk of recurrence and death. Molecular characterization may identify patients unlikely to achieve pCR. This neoadjuvant trial was conducted to determine the pCR rate with docetaxel and carboplatin and to identify molecular alterations and/or immune gene signatures predicting pCR. EXPERIMENTAL DESIGN: Patients with clinical stages II/III TNBC received 6 cycles of docetaxel and carboplatin. The primary objective was to determine if neoadjuvant docetaxel and carboplatin would increase the pCR rate in TNBC compared to historical expectations. We performed whole-exome sequencing (WES) and immune profiling on pre-treatment tumor samples to identify alterations that may predict pCR. Thirteen matching on-treatment samples were also analyzed to assess changes in molecular profiles. RESULTS: Fifty-eight of 127 (45.7%) patients achieved pCR. There was a non-significant trend toward higher mutation burden for patients with residual cancer burden (RCB) 0/I versus RCB II/III (median 80 versus 68 variants, p 0.88). TP53 was the most frequently mutated gene, observed in 85.7% of tumors. EGFR, RB1, RAD51AP2, SDK2, L1CAM, KPRP, PCDHA1, CACNA1S, CFAP58, COL22A1, and COL4A5 mutations were observed almost exclusively in pre-treatment samples from patients who achieved pCR. Seven mutations in PCDHA1 were observed in pre-treatment samples from patients who did not achieve pCR. Several immune gene signatures including IDO1, PD-L1, interferon gamma signaling, CTLA4, cytotoxicity, tumor inflammation signature, inflammatory chemokines, cytotoxic cells, lymphoid, PD-L2, exhausted CD8, Tregs, and immunoproteasome were upregulated in pre-treatment samples from patients who achieved pCR. CONCLUSION: Neoadjuvant docetaxel and carboplatin resulted in a pCR of 45.7%. WES and immune profiling differentiated patients with and without pCR. TRIAL REGISTRATION: Clinical trial information: NCT02124902, Registered 24 April 2014 & NCT02547987, Registered 10 September 2015.

Immunotherapy during the acute SHIV infection of macaques confers long-term suppression of viremia.

We report that combination bNAb immunotherapy initiated on day 3 post-infection (PI) maintained durable CD8+ T cell-mediated suppression of SHIVAD8 viremia and preinoculation levels of CD4+ T cells in 9 of 13 treated monkeys during nearly 6 yr of observation, as assessed by successive CD8+ T cell-depletion experiments. In an extension of that study, two treatment interventions (bNAbs alone or cART plus bNAbs) beginning on week 2 PI were conducted and conferred controller status to 7 of 12 monkeys that was also dependent on control mediated by CD8+ cells. However, the median time to suppression of plasma viremia following intervention on week 2 was markedly delayed (85 wk) compared with combination bNAb immunotherapy initiated on day 3 (39 wk). In both cases, the principal correlate of virus control was the induction of CD8+ T cellular immunity.

The association between residential proximity to brownfield sites and high-traffic areas and measures of immunity.

The mechanisms by which neighborhood environmental exposures influence health are poorly understood, although immune system dysregulation represents a potential biological pathway. While many neighborhood exposures have been investigated, there is little research on residential proximity to brownfield waste. Using biomarker data from 262 participants in the Detroit Neighborhood Health Study, we estimated the association between proximity to brownfields and heavy traffic and signal joint T-cell receptor excision circles (sjTRECs, a measure of naive T-cell production), C-reactive protein (CRP, a measure of systemic inflammation), and interleukin-6 (IL-6, a pro-inflammatory cytokine). We assessed residential proximity ≤200 m from brownfields and highways on all three biomarkers using multivariate regression. We demonstrated that living ≤200 m from a brownfield site was associated with a 0.30 (95% CI = 0.59, 0.02, p = 0.04) loge-unit decrease in sjTRECs per million whole blood cells, as well as non-significantly elevated levels of CRP and IL-6. Heavy traffic was not associated with any biomarker. Persons living in close proximity to brownfield sites had significantly lower naive T-cell production, suggesting accelerated immune aging. Decreased T-cell production associated with brownfield proximity may be caused by toxicant exposure in brownfield sites, or may serve as a marker of other neighborhood stressors.

Development of Immature CD4+CD8+T Cells Into Mature CD4+ T Cells Requires Alpha-1 Antitrypsin as Observed by Treatment in HIV-1 Infected and Uninfected Controls.

Immune cells are, by default, migratory cells that traverse tissue for the purpose of carrying out recognition and recruitment in pathologic inflammation and infection. Members of the LDL receptor family (LDL-RFMs) interact with human leukocyte elastase on the cell surface (HLE-CS) in complex with the abundant blood protein α1proteinase inhibitor (α1PI, α1-antitrypsin, Alpha-1), a process that induces internalization of aggregated functionally-related receptors, including CD4 and the T cell antigen receptor, while simultaneously promoting cellular locomotion. We sought to determine whether augmenting α1PI blood concentration would promote the locomotion of immature T cells through the thymus and generate new CD4+ T cells. Two small clinical trials (NCT01370018, NCT01731691, https://clinicaltrials.gov) were conducted in which HIV-1 infected and uninfected individuals were augmented with α1PI and compared with placebo-treated subjects and untreated controls. Blood cell phenotypes were monitored weekly. We found that CD4/CD8 ratio was significantly increased by α1PI augmentation in both uninfected and HIV-1 infected individuals. We found that maturation of CD4+CD8+ T cells to become immunologically competent CD4+ T cells was regulated by α1PI. We propose a strategy targeting HLE-CS for treating secondary immunodeficiency for which there is currently no direct treatment. Treatment to directly elevate T cells in patients with secondary immunodeficiency, including HIV disease, can be provided by alpha-1 antitrypsin augmentation or small molecules that target HLE-CS. Because individuals infected with HIV-1 produce a monoclonal antibody, 3F5, which binds to and inactivates α1PI, a process that prevents α1PI from binding to HLE-CS, thereby blocking locomotion of immature T cells through the thymus to generate CD4+ T cells, we further propose that HIV-1 vaccination should include induction of an antibody that binds to and blocks 3F5 activity, thereby preventing AIDS in addition to the current vaccine strategy for preventing HIV-1 infection.

HBeAg seroconversion is associated with a more effective PD-L1 blockade during chronic hepatitis B infection.

BACKGROUND & AIMS: Current therapies for chronic hepatitis B virus (HBV) infection control viral replication but do not eliminate the risk of progression to hepatocellular carcinoma. HBV-specific CD8 T cells are necessary for viral control, but they are rare and exhausted during chronic infection. Preclinical studies have shown that blockade of the PD-1:PD-L1 axis can restore HBV-specific T cell functionality. The aim of this study was to analyze how the clinical and treatment status of patients impacts the ability of HBV-specific T cells to respond to PD-L1 blockade. METHODS: Expression patterns of the PD-1:PD-L1/PD-L2 axis were analyzed in healthy donors and chronically infected patients in different clinical phases of disease. A functional assay was performed to quantify baseline HBV-specific T cell responses in chronically infected patients. Baseline responses were then compared to those attained in the presence of an anti-PD-L1 monoclonal antibody (MEDI2790). RESULTS: Chronically infected patients were characterized by the upregulation of PD-1 within the T cell compartment and a concomitant upregulation of PD-L1 on myeloid dendritic cells. The upregulation was maximal in HBV e antigen (HBeAg)-positive patients but persisted after HBeAg negativization and was not restored by long-term treatment. HBV reactivity, measured as frequency of HBV-specific T cells, was significantly higher in HBeAg-negative patients with lower HBV DNA levels, independently of HBV surface antigen or alanine aminotransferase levels. Anti-PD-L1 blockade with MEDI2790 increased both the number of IFN-γ-producing T cells and the amount of IFN-γ produced per cell in 97% of patients with detectable HBV reactivity, independently of patients' clinical or treatment status. CONCLUSION: Patients with lower levels of HBV DNA and the absence of HBeAg have more intact HBV-specific T cell immunity and may benefit the most from PD-L1 blockade as a monotherapy. LAY SUMMARY: Hepatitis B virus (HBV)-specific T cell responses during chronic infection are weak due to the upregulation of inhibitor molecules on the immune cells. In this study we show that the inhibitory PD-1:PD-L1 axis is upregulated during chronic HBV infection and successful antiretroviral therapy does not restore normal levels of PD-1 and PD-L1 expression. However, in HBV e antigen-negative patients, treatment with an anti-PD-L1 antibody can increase the functionality of HBV-specific T cell responses by an average of 2-fold and is a promising new therapy for patients with chronic HBV infection.

The Great Recession and Immune Function.

The Great Recession precipitated unprecedented home foreclosures increases, but documentation of related neighborhood changes and population health is scant. Using the Detroit Neighborhood Health Study (N = 277), we examined associations between neighborhood-level recession indicators and thymic function, a life course immunological health indicator. In covariate-adjusted multilevel models, each 10 percentage point increase in abandoned home prevalence and 1 percentage point increase in 2009 home foreclosures was associated with 1.7-year and 3.3-year increases in thymic aging, respectively. Associations attenuated after adjustment for neighborhood-level social cohesion, suggesting community ties may buffer recession-related immune aging. Effects of neighborhood stressors were strongest in middle-income households, supporting theory of excess vulnerability in this group. Future research should assess whether ongoing foreclosure and blight reduction efforts improve health for residents of recession impacted neighborhoods.

Circulating metabolomic profile can predict dyslipidemia in HIV patients undergoing antiretroviral therapy.

BACKGROUND AND AIMS: Dyslipidemia in HIV-infected patients is unique and pathophysiologically associated with host factors, HIV itself and the use of antiretroviral therapy (ART). The use of nuclear magnetic resonance spectroscopy (NMR) provides additional data to conventional lipid measurements concerning the number of lipoprotein subclasses and particle sizes. METHODS: To investigate the ability of lipoprotein profile, we used a circulating metabolomic approach in a cohort of 103 ART-naive HIV-infected patients, who were initiating non-nucleoside analogue transcriptase inhibitor (NNRTI)-based ART, and we subsequently followed up these patients for 36 months. Univariate and multivariate analyses were performed to evaluate the predictive power of NMR spectroscopy. RESULTS: VLDL-metabolism (including VLDL lipid concentrations, sizes, and particle numbers), total triglycerides and lactate levels resulted in good classifiers of dyslipidemia (AUC 0.903). Total particles/HDL-P ratio was significantly higher in ART-associated dyslipidemia compared to ART-normolipidemia (p = 0.001). Large VLDL-Ps were positively associated with both LDL-triglycerides (ρ 0.682, p < 0.001) and lactate concentrations (ρ 0.416, p < 0.001), the last one a marker of mitochondrial low oxidative capacity. CONCLUSIONS: Our data suggest that circulating metabolites have better predictive values for HIV/ART-related dyslipidemia onset than do the biochemical markers associated with conventional lipid measurements. NMR identifies changes in VLDL-P, lactate and LDL-TG as potential clinical markers of baseline HIV-dyslipidemia predisposition. Differences in circulating metabolomics, especially differences in particle size, are indicators of important derangements of mitochondrial function that are linked to ART-related dyslipidemia.

Accumulation of follicular CD8+ T cells in pathogenic SIV infection.

LN follicles constitute major reservoir sites for HIV/SIV persistence. Cure strategies could benefit from the characterization of CD8+ T cells able to access and eliminate HIV-infected cells from these areas. In this study, we provide a comprehensive analysis of the phenotype, frequency, localization, and functionality of follicular CD8+ T cells (fCD8+) in SIV-infected nonhuman primates. Although disorganization of follicles was a major factor, significant accumulation of fCD8+ cells during chronic SIV infection was also observed in intact follicles, but only in pathogenic SIV infection. In line with this, tissue inflammatory mediators were strongly associated with the accumulation of fCD8+ cells, pointing to tissue inflammation as a major factor in this process. These fCD8+ cells have cytolytic potential and can be redirected to target and kill HIV-infected cells using bispecific antibodies. Altogether, our data support the use of SIV infection to better understand the dynamics of fCD8+ cells and to develop bispecific antibodies as a strategy for virus eradication.

Immune Correlates of Natural HIV Elite Control and Simultaneous HCV Clearance-Supercontrollers.

HIV-elite controllers are a minority group of HIV-infected patients with the ability to maintain undetectable HIV viremia for long time periods without antiretroviral treatment. A small group of HIV-controllers are also able to spontaneously clear the hepatitis C virus (HCV) whom we can refer to as "supercontrollers." There are no studies that explore immune correlates looking for the mechanisms implicated in this extraordinary phenomenon. Herein, we have analyzed HCV- and HIV-specific T-cell responses, as well as T, dendritic and NK cell phenotypes. The higher HCV-specific CD4 T-cell polyfunctionality, together with a low activation and exhaustion T-cell phenotype was found in supercontrollers. In addition, the frequency of CD8 CD161high T-cells was related with HIV- and HCV-specific T-cells polyfunctionality. Interesting features regarding NK and plasmacytoid dendritic cells (pDCs) were found. The study of the supercontroller's immune response, subjects that spontaneously controls both chronic viral infections, could provide further insights into virus-specific responses needed to develop immunotherapeutic strategies in the setting of HIV cure or HCV vaccination.

HIV-Specific CD8+ T Cells Exhibit Reduced and Differentially Regulated Cytolytic Activity in Lymphoid Tissue.

Elimination of lymphoid tissue reservoirs is a key component of HIV eradication strategies. CD8+ T cells play a critical role in control of HIV, but their functional attributes in lymph nodes (LNs) remain unclear. Here, we show that memory, follicular CXCR5+, and HIV-specific CD8+ T cells from LNs do not manifest the properties of cytolytic CD8+ T cells. While the frequency of follicular CXCR5+ CD8+ T cells was strongly inversely associated with peripheral viremia, this association was not dependent on cytolytic CXCR5+ CD8+ T cells. Moreover, the poor cytolytic activity of LN CD8+ T cells was linked to a compartmentalized dissociation between effector programming and the transcription factor T-bet. In line with this, activation of LN CD8+ T cells only partially induced the acquisition of cytolytic functions relative to peripheral blood CD8+ T cells. These results suggest that a state of immune privilege against CD8+ T cell-mediated cytolysis exists in lymphoid tissue, potentially facilitating the persistence of HIV.

Thymic Function Failure Is Associated With Human Immunodeficiency Virus Disease Progression.

Background: Thymic function has been mainly analyzed with surrogate peripheral markers affected by peripheral T-cell expansion, making it difficult to assess the role of thymic failure in human immunodeficiency virus (HIV) disease progression. The assay of signal-joint/DßJß T-cell rearrangement excision circles (sj/ß-TREC ratio) overcomes this limitation but has only been assayed in small cohorts. Thus, the aim of this study was to determine the role of thymic function, measured by the sj/ß-TREC ratio, on CD4 T-cell maintenance in prospective HIV cohorts that include patients with a wide age range and different immunological phenotypes. Methods: Seven hundred seventy-four patients including typical progressors, long-term nonprogressors (LTNPs), and vertically HIV-infected subjects were analyzed. Thymic function was quantified in peripheral blood samples using the sj/ß-TREC ratio. Associations between thymic function and CD4 T-cell dynamics and combination antiretroviral therapy (cART) onset were analyzed using linear, logistic, and Cox proportional hazard models. Results: Thymic function failure (sj/ß-TREC ratio <10) was independently associated with HIV progression. In agreement, patients with distinctive high CD4 T-cell levels and low progression rates (vertically HIV-infected patients and LTNPs, including HIV controllers) had significantly higher thymic function levels whereas patients with thymic function failure had lower CD4 T-cell levels, lower nadir, and faster CD4 T-cell decay. Conclusions: This work establishes the relevance of thymic function, measured by sj/ß-TREC ratio, in HIV disease progression by analyzing a large number of patients in 3 cohorts with different HIV disease progression phenotypes. These results support and help to understand the mechanisms underlying the rationale of early cART onset.

Follicular CD8 T cells accumulate in HIV infection and can kill infected cells in vitro via bispecific antibodies.

Cytolytic CD8 T cells play a crucial role in the control and elimination of virus-infected cells and are a major focus of HIV cure efforts. However, it has been shown that HIV-specific CD8 T cells are infrequently found within germinal centers (GCs), a predominant site of active and latent HIV infection. We demonstrate that HIV infection induces marked changes in the phenotype, frequency, and localization of CD8 T cells within the lymph node (LN). Significantly increased frequencies of CD8 T cells in the B cell follicles and GCs were found in LNs from treated and untreated HIV-infected individuals. This profile was associated with persistent local immune activation but did not appear to be directly related to local viral replication. Follicular CD8 (fCD8) T cells, despite compromised cytokine polyfunctionality, showed good cytolytic potential characterized by high ex vivo expression of granzyme B and perforin. We used an anti-HIV/anti-CD3 bispecific antibody in a redirected killing assay and found that fCD8 T cells had better killing activity than did non-fCD8 T cells. Our results indicate that CD8 T cells with potent cytolytic activity are recruited to GCs during HIV infection and, if appropriately redirected to kill HIV-infected cells, could be an effective component of an HIV cure strategy.

Tuberculosis Therapy Modifies the Cytokine Profile, Maturation State, and Expression of Inhibitory Molecules on Mycobacterium tuberculosis-Specific CD4+ T-Cells.

BACKGROUND: Little is known about the expression of inhibitory molecules cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed-death-1 (PD-1) on Mycobacterium tuberculosis (Mtb)-specific CD4 T-cells and how their expression is impacted by TB treatment. METHODS: Cryopreserved PBMCs from HIV-TB co-infected and TB mono-infected patients with untreated and treated tuberculosis (TB) disease were stimulated for six hours with PPD and stained. Using polychromatic flow cytometry, we characterized the differentiation state, cytokine profile, and inhibitory molecule expression on PPD-specific CD4 T-cells. RESULTS: In our HIV-TB co-infected cohort, TB treatment increased the proportion of PPD-specific CD4 T-cells co-producing IFN-γ+IL-2+TNF-α+ and IFN-γ+IL-2+ (p = 0.0004 and p = 0.0002, respectively) while decreasing the proportion of PPD-specific CD4 T-cells co-producing IFN-γ+MIP1-ß+TNF-α+ and IFN-γ+MIP1-ß+. The proportion of PPD-specific CD4 T-cells expressing an effector memory phenotype decreased (63.6% vs 51.6%, p = 0.0015) while the proportion expressing a central memory phenotype increased (7.8% vs. 21.7%, p = 0.001) following TB treatment. TB treatment reduced the proportion of PPD-specific CD4 T-cells expressing CTLA-4 (72.4% vs. 44.3%, p = 0.0005) and PD-1 (34.5% vs. 29.2%, p = 0.03). Similar trends were noted in our TB mono-infected cohort. CONCLUSION: TB treatment alters the functional profile of Mtb-specific CD4 T-cells reflecting shifts towards a less differentiated maturational profile and decreases PD-1 and CTLA-4 expression. These could serve as markers of reduced mycobacterial burden. Further study is warranted.