T-cell Compartment Research Articles

CLL-220: Modulation of Phenotypic and Functional Features of Immune Cells in Chronic Lymphocytic Leukemia Patients Treated with Ibrutinib

Context Chronic lymphocytic leukemia (CLL) is characterized by deep immune alterations, increased susceptibility to infections and immune evasion of tumor cells. Besides its direct anti-tumor activity, ibrutinib has shown to exert immunomodulatory effects. Objective The aim of this study was to analyze immune changes occurring in CLL patients treated with ibrutinib. Patients and methods Peripheral blood samples were collected from 22 CLL patients with progressive disease (PD-CLL) before ibrutinib start and after 1, 6, and 12 months of therapy. For comparison, 10 CLL patients with stable disease (SD-CLL), and 7 healthy donors were also enrolled. The phenotype of immune cells was assessed by flow cytometry. Cytotoxic activity was evaluated by CD107 assay. Results After 6 months of ibrutinib treatment we observed a decrease of circulating CLL cells, which was paralleled by a reduction of CD3+, CD4+, CD8+ T cells, and T regs in the peripheral blood. Already after 1 month of ibrutinib therapy, we found a normalization in the upregulated expression of the activation marker CD69 on T cells and subsequently (i.e. at month 12) a significant reduction in the expression of the inhibitory receptor CTLA-4. Other checkpoint molecules (i.e. TIGIT, CD96, PD-1, TIM-3, and BTLA) were not modulated on T cells by ibrutinib therapy. In the Vγ9Vδ2 T-cell compartment, we observed a reduced expression of the inhibitory receptor CD96 after 12 months of treatment, which was paralleled by an improvement in the cytotoxic functions. In NK cells, a reduced expression of CD69 and CD96—both upregulated at the baseline—and a recovery in CD16 expression, which was significantly lower in PD-CLL compared to SD-CLL, were detected after 6 months of treatment. By contrast, ibrutinib did not restore the compromised cytotoxicity of NK cells. Of note, when we categorized patients based on IWCLL response, we found that the modifications occurring in all immune compartments were exclusively confined to patients achieving a response and were not detectable in non-responder patients. Conclusion Overall, our results show that ibrutinib exerts a wide range of immune-modulating effects, which are associated with the achievement of a clinical response to therapy.

CD248+CD8+ T lymphocytes suppress pathological vascular remodeling in human thoracic aortic aneurysms.

Aortic aneurysms are characterized by vascular inflammation, neovascularization, and extracellular matrix destruction of the aortic wall. Although experimental studies indicate a potential role of CD248 in microvessel remodeling, the functions of CD248 in human vascular pathologies remain unexplored. Here we aimed to study how CD248 interferes with pathological vascular remodeling of human aortic aneurysms. Immunofluorescent staining showed that CD248 expression was mainly localized in the CD8+ T cells infiltrating in the adventitia and media of aortic walls of patients with ascending thoracic aortic aneurysms. qPCR and immunofluorescent staining analyses revealed increased aortic CD248 expression and infiltrating CD248+CD8+ T cells in aortic aneurysms than in nonaneurysmal aortas. Flow cytometry analysis of human peripheral blood further identified a fraction of circulating CD248+ cells which was confined in the CD8+ T-cell compartment. The increased infiltrating of CD248+CD8+ T cells was coincident with reduced circulating CD248+CD8+ T cells in patients with ascending TAA when compared with patients with coronary artery diseases and healthy donors. The CD248+CD8+ T cells were characterized by upregulated IL-10 and downregulated IL-1β/INF-γ expression when compared with CD248-CD8+ T cells. Moreover, when co-cultured with human aortic endothelial cells, the CD248+CD8+ T cells not only downregulated endothelial expression of ICAM1/VCAM1 and MMP2/3 but also suppressed endothelial migration. This study shows that CD248 reduces pathological vascular remodeling via anti-inflammatory CD248+CD8+ T cells, revealing a CD248-mediated cellular mechanism against human aortic aneurysms.

TARGETING CD4+ T CELL METABOLISM PROVIDES AN EFFECTIVE AND AGE-SPECIFIC IMMUNOSUPPRESSION

Targeting T-cell metabolism may provide an effective immunosuppression. We delineated the correlation of aging and T cell metabolism. Moreover, we defined the consequences of metabolic changes in T-cell compartments on alloimmunity and delineated specific and novel immunosuppressive targets on CD-4+ T-cells. We collected naïve CD4+ T cells (splenocytes) of young and old (3 and 18 months) C67BL/6 mice. Following activation with anti-CD3 and anti-CD28 (24 hrs), we evaluated oxidative phosphorylation (OXPHOS) and aerobic glycolysis by oxygen consumption (OCR) and extracellular acidification (ECAR) using a Seahorse XFe96 extracellular flux analyzer. Graft survival, T-cell specificity and a detailed immune profiling were recorded serially. Upon activation in-vitro, a compromised utilization of OXPHOS and glycolysis pathways was observed in old CD4+ T cells (p<0.0001), indicating failure of old CD4+ T cells to exhibit adequate metabolic reprogramming. Further analysis of metabolic pathways revealed a critical role of glutaminolysis in T cell activation. 6-diazo-5-oxo-l-norleucine (DON), an analog of glutamine inhibiting critical enzymes of glutaminolysis resulted into an age-specific reduced activation and proliferative capacities of CD4+T cells. Notably, lower doses of DON inhibited IL-2 production and CFSE-determined proliferation only in old but not young CD4+ T cells (p<0.001). Utilizing a pre-clinical fully mismatched transplantation model, we observed inversed CD4:CD8 ratio in old recipients following DON (1.6mg/kg every other day). Graft survival was prolonged in young recipients, from 7 to 18 days (p< 0.01). Notably, was a drastic and age-specific effect of DON on graft skin graft survival in old recipients to 42 days (n=7, p<0.001). Targeting metabolic pathways was specific to CD4+ T-cells. Adoptively transferring young CD4+ T cells reversed the prolonged survival observed in old recipients. Depletion of CD8+ T cells did not alter transplant outcomes of DON in either young or old recipients. Taken together, we introduce a detailed and age-specific analysis of metabolic pathways in T cells and introduce a novel concept for an optimized immunosuppression in old recipients.

Germline TET2 loss of function causes childhood immunodeficiency and lymphoma

AbstractMolecular dissection of inborn errors of immunity can help to elucidate the nonredundant functions of individual genes. We studied 3 children with an immune dysregulation syndrome of susceptibility to infection, lymphadenopathy, hepatosplenomegaly, developmental delay, autoimmunity, and lymphoma of B-cell (n = 2) or T-cell (n = 1) origin. All 3 showed early autologous T-cell reconstitution following allogeneic hematopoietic stem cell transplantation. By whole-exome sequencing, we identified rare homozygous germline missense or nonsense variants in a known epigenetic regulator of gene expression: ten-eleven translocation methylcytosine dioxygenase 2 (TET2). Mutated TET2 protein was absent or enzymatically defective for 5-hydroxymethylating activity, resulting in whole-blood DNA hypermethylation. Circulating T cells showed an abnormal immunophenotype including expanded double-negative, but depleted follicular helper, T-cell compartments and impaired Fas-dependent apoptosis in 2 of 3 patients. Moreover, TET2-deficient B cells showed defective class-switch recombination. The hematopoietic potential of patient-derived induced pluripotent stem cells was skewed toward the myeloid lineage. These are the first reported cases of autosomal-recessive germline TET2 deficiency in humans, causing clinically significant immunodeficiency and an autoimmune lymphoproliferative syndrome with marked predisposition to lymphoma. This disease phenotype demonstrates the broad role of TET2 within the human immune system.

Cellular and molecular profiling of T-cell subsets at the onset of human acute GVHD

AbstractThe cellular and molecular processes involved in acute graft-versus-host disease (aGVHD) development early after allogeneic hematopoietic cell transplantation (HCT) in humans remain largely unknown. We have performed multiparameter immunophenotyping and molecular profiling of CD4+and CD8+T cells in 2 independent cohorts of patients undergoing HCT, as well as in their HLA-identical sibling donors. Cellular profiling using spectral flow cytometry showed an incomplete reconstitution of the T-cell compartment in recipients without aGVHD early after transplantation, as well as a shift toward an effector memory phenotype, paralleled by depletion of the naive T-cell pool. Molecular profiling of T-cell populations in donors vs recipients without aGVHD revealed increased pathway activity of >40 gene modules in recipients. These pathways were associated in particular with T-cell activation, adhesion, migration, and effector functions. Cellular profiles from recipients developing aGVHD displayed an enrichment of cells with a T memory stem cell–like phenotype compared with recipients without aGVHD. Comparison of gene profiles from these recipients revealed that transforming growth factor-β (TGF-β) signaling was most significantly downregulated, whereas the pathway activity of NF-κB–associated transcription factors and signaling pathways were increased, at aGVHD onset. This study suggests that the integration of cellular and molecular profiles provides new insights into the development of aGVHD in humans.

Abstract 1516: Deep profiling of T-cell repertoire and tumor heterogeneity in chronic lymphocytic leukemia patients following allogeneic T-cell therapy

Abstract Chemotherapy/ targeted therapy are both known to trigger evolution of treatment resistant clones that can lead to relapse. Allogeneic stem cell transplant (alloSCT) for refractory Chronic Lymphocytic Leukemia (CLL) patients is associated with better outcomes. We hypothesized that allogeneic T-cell immunotherapies, including alloSCT and donor lymphocyte infusion (DLI) would impact tumor evolution through the application of selective immunologic pressure with reciprocal changes in the T-cell compartment. Here, we tested a cohort of 24 heavily pre-treated CLL patients treated. Treatments consisted of alloSCT alone, or with follow-up DLI, which are two established mediators of effective Graft versus Leukemia (GVL). Our cohort included 11 patients who relapsed (denoted as non-responder, NR) after alloSCT and 13 patients who had complete response (CR) after alloSCT, with 11/13 patients showing durable CR with a median post-transplant overall survival (OS) of 9.8 years. We mapped the evolutionary trajectories of tumor cells by whole exome sequencing (WES) of sort purified CLL in post-transplant relapsed patients. To investigate changes in immune repertoire and gene expression post-transplant, CD3 positive T-cells from peripheral blood and bone marrows of CLL patients at complete donor chimerism were analyzed both at bulk and at the single cell level. We found evidence of subclonal leukemic evolution in the majority of our CLL patient cohort after nonmyeloablative HLA-matched alloSCT. Different patterns of CLL evolution were observed, and these changes included putative CLL drivers in every case. In all of the 11 patients with longitudinal post-alloSCT samples available, we observed branched CLL evolution in 4 patients, linear evolution in 4 patients, and no evolution in 3 patients. These data suggest that differential sensitivity of leukemic subclones to allogeneic T cell killing may underlie the branched and linear evolution that we observed, and therefore can shape leukemic subclonal architecture after transplant. Of note, we found that clonal CLL was more responsive to alloSCT in comparison to CLL with subclonal disease architecture.To identify T-cells with GVL potential, we first cataloged potential neoantigens by screening mutated regions in CLL with in silico HLA binding prediction models. Neoantigen specific T-cells were then sorted from longitudinal peripheral blood samples using tetramers, followed by identification of GVL specific TCR in both bulk and single cell setting. We were able to identify T-cells that coevolved with specific tumorigenic lesions in a subset of CLL patients. Taken together, our results suggest that donor-derived antigen-specific T-cells mediate clonal selection of CLL with concurrent changes in allogeneic T-cells, and that these changes can be monitored in longitudinal patient samples. Citation Format: Celine Kerros, John P. Miller, Xizeng Mao, Haven R. Garber, Hannah C. Beird, Jianhua Zhang, Jason Roszik, Paul Leonard, Li Zhao, Sahil Seth, Pei Lin, Huandong Sun, William G. Wierda, Issa F. Khouri, Karen Clise-Dwyer, Andrew Futreal, Shoudan Liang, Koppikar Priya, Jeffrey Molldrem. Deep profiling of T-cell repertoire and tumor heterogeneity in chronic lymphocytic leukemia patients following allogeneic T-cell therapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1516.

Children From the Age of Three Show a Developmental Switch in T-Cell Differentiation.

Every sixth child suffers from hypertrophy of the adenoid, a secondary lymphoid organ, at least once in childhood. Little is known about the impact of pathogen-provocation vs. developmental impact on T-cell responses after 1 year of age. Therefore, developmental and infection-driven influences on the formation of T-cell-compartments and -multifunctionality in adenoids were analyzed taking into account patient's history of age and inflammatory processes. Here, we show that in adenoids of 102 infants and children similar frequencies of naïve, effector, and memory T-cells were accumulated, whereby history of suffering from subsequent infection symptoms resulted in lower frequencies of CD4+ and CD8+ T-cells co-expressing several cytokines. While patients suffering from sole nasal obstruction had balanced Th1- and Th17-compartments, Th1 dominated in patients with concomitant upper airway infections. In addition, analysis of cytokine co-expressing CD4+ and CD8+ T-cells showed that children at the age of three or older differed significantly from those being 1- or 2-years old, implicating a developmental switch in T-cell differentiation at that age. Yet, dissecting age and infectious history of the patients revealed that while CD8+ T-cell differentiation seems to be triggered by development, CD4+ T-cell functionality is partly impaired by infections. However, this functionality recovers by the age of 3 years. Thus, 3 years of age seems to be a critical period in an infant's life to develop robust T-cell compartments of higher quality. These findings identify important areas for future research and distinguish an age period in early childhood when to consider adjusting the choice of treatment of infections.

Human Immunodeficiency Virus-Negative Men Who Have Sex With Men Have an Altered T-Cell Phenotype and Bioenergy Metabolism

BackgroundWe recently reported that the levels of activation, exhaustion, and terminal differentiation within the peripheral T-cell compartment were increased in men who have sex with men (MSM) compared with blood bank donors. During activation and differentiation, T cells undergo metabolic changes to maintain their energy demand.MethodsThe effect of cytomeglovirus (CMV) infection and risk behavior on the immune phenotype of peripheral T cells and the immune bioenergy metabolism profile in human immunodeficiency virus-negative MSM (with high or low sexual risk behavior) and blood bank donors was evaluated.ResultsMen who have sex with men exhibited increased levels of T-cell activation and terminal differentiation and an impairment of the bioenergy metabolism (mitochondrial respiration and glycolysis) compared with blood bank donors. Cytomeglovirus infection was associated with increased terminal differentiation of CD4+ (B = 3.41; 95% confidence interval [CI], 1.98–4.85; P < .0001) and CD8+ T cells (CD57+: B = 1.21, 95% CI = 0.41–2.02, P = .004; CD27−CD28−: B = 2.20, 95% CI = 1.21–3.18, P < .0001; and CD57+ of CD28−: B = 1.02, 95% CI = 0.38–1.66, P = .002) and increased glycolysis (B = 0.97; 95% CI, 0.27–1.67; P = .007). Risk behavior was associated with increase activation of CD4+ T cells (B = 0.22; 95% CI, 0.07–0.37; P = .005), increased terminal differentiation of CD4+ (B = 0.82; 95% CI, 0.44–1.20; P < .0001) and CD8+ T cells (B = 1.55; 95% CI, 0.58–2.51; P = .002), and decreased glycolysis (glycolysis: B = −0.40, 95% CI = −0.68 to 0.12, P = .006; and glycolytic capacity: B = −0.54, 95% CI = −0.91 to 0.16, P = .005).ConclusionsMen who have sex with men show an increased prevalence of bloodborne and sexually transmitted infection, indicating that immunological changes in the T-cell population and the bioenergy metabolism observed in MSM can most likely be attributed to chronic antigen exposure.

Efficient T-Cell Compartment in HIV-Positive Patients Receiving Orthotopic Liver Transplant and Immunosuppressive Therapy.

In patients undergoing orthotopic liver transplant (OLT), immunosuppressive treatment is mandatory and infections are leading causes of morbidity/mortality. Thus, it is essential to understand the functionality of cell-mediated immunity after OLT. The aim of the study was to identify changes in T-cell phenotype and polyfunctionality in human immunodeficiency virus-positive (HIV+) and -negative (HIV-) patients undergoing immunosuppressive treatment after OLT. We studied peripheral blood mononuclear cells from 108 subjects divided into 4 groups of 27: HIV+ transplanted patients, HIV- transplanted patients, HIV+ nontransplanted patients, and healthy subjects. T-cell activation, differentiation, and cytokine production were analyzed by flow cytometry. Median age was 55 years (interquartile range, 52-59 years); the median CD4 count in HIV+ patients was 567 cells/mL, and all had undetectable viral load. CD4+ and CD8+ T-cell subpopulations showed different distributions between HIV+ and HIV- OLT patients. A cluster representing effector cells expressing PD1 was abundant in HIV- transplanted patients and they were characterized by higher levels of CD4+ T cells able to produce interferon-γ and tumor necrosis factor-α. HIV- transplanted patients have more exhausted or inflammatory T cells compared to HIV+ transplanted patients, suggesting that patients who have already experienced a form of immunosuppression due to HIV infection respond differently to anti-rejection therapy.

SO-26 Clinical efficacy of combined BRAF, MEK, and PD-1 inhibition in BRAFV600E colorectal cancer patients

While combinations of BRAF inhibitors with EGFR and/or MEK inhibitors have improved efficacy in BRAFV600E colorectal cancer (CRC), response rates remain low and durability is limited. Preclinical and correlative studies suggest that targeting BRAF signaling in combination with immune checkpoint inhibition could enhance activity. BRAFV600E CRC patients recruited from the Massachusetts General Hospital Cancer Center or the Dana-Farber Cancer Institute were treated with the PD-1 inhibitor spartalizumab (PDR001) 400mg IV q28d, dabrafenib 150mg PO BID, and trametinib 2mg PO daily. Single-cell RNAseq was performed on paired baseline and day 15 tumor biopsies, patient-derived organoids were established from baseline biopsies, and serial ctDNA was analyzed. To date, 21 BRAFV600E CRC patients have been enrolled (4 MSI, 17 MSS). 5 had prior therapy with BRAF inhibitors and/or immunotherapy. Median age was 64 (range 35-86) and 12 (57%) were female. Regimen was well-tolerated with rash, fever, and diarrhea as the most common AEs. Of 20 patients with at least one restaging scan, ORR was 35% (7/20) and disease control rate of 75%, which compares favorably to the historical 12% ORR of dabrafenib plus trametinib alone in BRAFV600E CRC. 45% (9/20) patients remained on therapy for >6 months, and one MSS patient remains on therapy >16 months with -100% reduction by RECIST. Among 12 MSS patients with no prior BRAF inhibitor or immunotherapy, response rate was 42% (5/12), and all 12 patients exhibited a reduction in tumor size. Response rate in MSI patients was 25% (1/4) with two remaining on therapy >6 months. Serial ctDNA analysis showed profound and sustained reduction in BRAFV600E ctDNA levels in responders and emergence of MAPK pathway alterations upon acquired resistance. Single-cell RNAseq of paired pre-treatment and day 15 on-treatment biopsies revealed increased infiltration by T-cells and other immune populations with therapy, as well as increased expression of cytotoxic genes specifically in the T-cell compartment. Single-cell RNAseq also confirmed inhibition of MAPK signature genes specifically in the tumor cell compartment, as well as induction of antigen presentation genes and other immune-modulatory programs within tumor cells. Patient-derived organoids treated with dabrafenib and trametinib exhibited gene expression changes that mirrored the changes observed in single-cell RNAseq of tumor cells in paired biopsies from the same trial patient from which they were derived. Spartalizumab, dabrafenib, and trametinib was well-tolerated and produced favorable response rates and durability relative to historical controls in BRAFV600E CRC patients. Correlative studies, including single-cell RNAseq of paired pre-treatment and on-treatment tumor biopsies and analysis of patient-derived organoids suggest potential mechanistic links that could underlie cooperativity between BRAF targeting and immune checkpoint inhibition. Updated data will be presented.

T-cell Response To Exercise Training Among Women At Heightened Risk Of Breast Cancer.

Aging causes changes in the peripheral T-cell compartment that may increase susceptibility to cancer and lower immune responses. Fitness is associated with lower frequencies of highly differentiated T-cells, increased naïve T-cells, and elevations in myokines such as IL-7 that contribute to naïve T-cell output, indicating that exercise may help preserve immunity. PURPOSE: Examine the impact of exercise training on the differentiation status of CD4+ and CD8+ T-cells, recent thymic emigrants (RTE), and plasma levels of IL-7 in older women with an elevated risk of breast cancer (obesity status, postmenopausal, elevated Gail and/or lifetime risk score or history of non-invasive breast cancer). METHODS: 44 women (VO2=19.58±3.37 ml/kg/min) were randomized to: high-intensity interval training (HIIT; n=16; 63.73±6.86yrs); moderate continuous exercise (MCE; n=14.; 64.62±12.21yrs); or control (CNT; n=14; 63.35±6.99yrs). Participants completed clinically supervised treadmill exercise 3x/week for 12 weeks using heart rate training. Naive (NA), central memory (CM), effector memory (EM) and CD45RA+ effector memory (EMRA) CD4+ and CD8+ T-cells, and RTE (CD4NA or CD8NA CD31+CD103+) in blood were quantified before and after training. Fold changes (cells/μl) were calculated by (post-pre)/pre and compared across groups via ANOVA with p<0.05 considered significant. RESULTS: 11, 10, and 11 participants completed the HIIT, MCE, and CNT training, respectively. Compared to HIIT, MCE increased total lymphocytes (-0.05±0.13 vs. 0.12±0.12), CD4 (-0.29±0.24 vs. 0.21±0.30), CD4 CM (-0.23±0.20 vs. 0.36±0.27), CD4NA (-0.33±0.32 vs. 0.31±0.39), and CD8EM (-0.16±0.31 vs. 0.32±0.31). The change in number of CD4CM was higher in MCE compared to CNT (0.36±0.27 vs. -0.24±0.42). No changes were found for IL-7 or RTEs. CONCLUSION: Immune responses to exercise training in women with an elevated risk of breast cancer are likely to vary depending on the intensity of exercise. Future research should focus on investigating the potential that exercise may have on T-cell phenotypes and their relation to breast cancer risk. Funded by NCI R25 CA057730, the MD Anderson Cancer Center/Energy Balance Assessment Supplemental Funding, MD Anderson Cancer Center, Center for Energy Balance in Cancer Prevention and Survivorship, UA T32CA009213.

CD4+ T cells persist for years in the human small intestine and display a TH1 cytokine profile.

Studies in mice and humans have shown that CD8+ T cell immunosurveillance in non-lymphoid tissues is dominated by resident populations. Whether CD4+ T cells use the same strategies to survey peripheral tissues is less clear. Here, examining the turnover of CD4+ T cells in transplanted duodenum in humans, we demonstrate that the majority of CD4+ T cells were still donor-derived one year after transplantation. In contrast to memory CD4+ T cells in peripheral blood, intestinal CD4+ TRM cells expressed CD69 and CD161, but only a minor fraction expressed CD103. Functionally, intestinal CD4+ TRM cells were very potent cytokine producers; the vast majority being polyfunctional TH1 cells, whereas a minor fraction produced IL-17. Interestingly, a fraction of intestinal CD4+ T cells produced granzyme-B and perforin after activation. Together, we show that the intestinal CD4+ T-cell compartment is dominated by resident populations that survive for more than 1 year. This finding is of high relevance for the development of oral vaccines and therapies for diseases in the gut.

Extremely low viral reservoir in treated chronically HIV-1-infected individuals.

BackgroundSmall viral reservoirs are found predominantly in HIV-1 controllers and individuals treated during acute/early HIV-1 infection. However, other HIV+ individuals could naturally also harbour low viral reservoirs.MethodsWe screened 451 HIV-1-infected treated-individuals with suppressed plasma viremia for at least 3 years and stored cryopreserved peripheral blood mononuclear cells (PBMCs). Total HIV-DNA was analysed in PBMCs with ddPCR. Individuals with <50 HIV-DNA copies/106 PBMCs constitute the ‘Low Viral Reservoir Treated’ cohort (LoViReT). Longitudinal samples were obtained from 12 chronically treated LoViReT and compared to 13 controls (>50 HIV-DNA copies/106 PBMCs) to analyse total HIV-DNA, T-cell and NK-cell populations, HIV-1 specific antibodies, and plasma inflammation markers.FindingsWe found that 9.3% of the individuals screened had <50 HIV-DNA copies/106 PBMCs. At least 66% initiated cART during the chronic phase of HIV-1 infection (cp-LoViReT). Cp-LoViReT harboured lower levels of HIV-DNA before cART and after treatment introduction the decays were greater compared to controls. They displayed a marked decline in quantity and avidity in HIV-specific antibodies after initiation of cART. Cp-LoViReT had fewer CD8+ TTM and TEMRA in the absence of cART, and higher CD8+ TN after 18 months on therapy.InterpretationTreated chronically HIV-1-infected LoViReT represent a new phenotype of individuals characterized by an intrinsically reduced viral reservoir, less impaired CD8+ T-cell compartment before cART, and low circulating HIV-1 antigens despite being treated in the chronic phase of infection. The identification of this unique group of individuals is of great interest for the design of future eradication studies.FundingMSD Spain

Immune reconstitution in children following chemotherapy for acute leukemia.

Although survival rates for pediatric acute lymphoblastic leukemia are now excellent, this is at the expense of prolonged chemotherapy regimens. We report the long‐term immune effects in children treated according to the UK Medical Research Council UKALL 2003 protocol. Peripheral blood lymphocyte subsets and immunoglobulin levels were studied in 116 participants, at six time points, during and for 18‐month following treatment, with 30‐39 patients analyzed at each time point.Total lymphocytes were reduced during maintenance chemotherapy and remained low 18 months following treatment completion. CD4 T cells remained significantly reduced 18 months after treatment, but CD8 cells and natural killer cells recovered to normal values. The fall in naïve B‐cell numbers during maintenance was most marked, but numbers recovered rapidly after cessation of treatment. Memory B cells, particularly nonclass‐switched memory B cells, remained below normal levels 18 months following treatment. All immunoglobulin subclasses were reduced during treatment compared to normal values, with IgM levels most affected.This study demonstrates that immune reconstitution differs between lymphocyte compartments. Although total B‐cell numbers recover rapidly, disruption of memory/naïve balance persists and T‐cell compartment persist at 18 months. This highlights the impact of modern chemotherapy regimens on immunity, and thus, infectious susceptibility and response to immunization.

\u03b3\u03b4 T cells compose a developmentally regulated intrauterine population and protect against vaginal candidiasis

This most comprehensive analysis to date of γδ T cells in the murine uterus reveals them to compose a unique local T-cell compartment. Consistent with earlier reports, most cells expressed a canonical Vγ6Vδ1 TCR, and produced interleukin (IL)-17A upon stimulation. Nonetheless, contrasting with earlier reports, uterine γδ T cells were not obviously intraepithelial, being more akin to sub-epithelial Vγ6Vδ1+ T cells at several other anatomical sites. By contrast to other tissues however, the uterine compartment also included non-Vγ6+, IFN-γ-producing cells; was strikingly enriched in young mice; expressed genes hitherto associated with the uterus, including the progesterone receptor; and did not require microbes for development and/or maintenance. This notwithstanding, γδ T-cell deficiency severely impaired resistance to reproductive tract infection by Candida albicans, associated with decreased responses of IL-17-dependent neutrophils. These findings emphasise tissue-specific complexities of different mucosal γδ cell compartments, and their evident importance in lymphoid stress-surveillance against barrier infection.

Clonal hematopoiesis in angioimmunoblastic T-cell lymphoma with divergent evolution to myeloid neoplasms

AbstractTET2 and DNMT3A mutations are frequently identified in T-cell lymphomas of T follicular helper cell origin (TCL-TFH), clonal hematopoiesis (CH), and myeloid neoplasms (MNs). The relationships among these 3 entities, however, are not well understood. We performed comprehensive genomic studies on paired bone marrow and tissue samples as well as on flow cytometry–sorted bone marrow and peripheral blood subpopulations from a cohort of 22 patients with TCL-TFH to identify shared CH-type mutations in various hematopoietic cell compartments. Identical mutations were detected in the neoplastic T-cell and myeloid compartments of 15 out of 22 patients (68%), including TET2 (14/15) and DNMT3A (10/15). Four patients developed MNs, all of which shared CH-type mutations with their TCL-TFH; additional unique genetic alterations were also detected in each patient's TCL-TFH and MN. These data demonstrate that CH is prevalent in patients with TCL-TFH and that divergent evolution of a CH clone may give rise to both TCL-TFH and MNs.

The sialyltransferase ST3Gal-IV guides murine T-cell progenitors to the thymus

AbstractT lymphocytes are important players in beneficial and detrimental immune responses. In contrast to other lymphocyte populations that develop in the bone marrow, T-cell precursors need to migrate to the thymus for further development. The interaction of P-selectin and P-selectin glycoprotein ligand-1 (PSGL-1) is crucial for thymic entry of T-cell precursors during settings of T-cell lineage reconstitution. PSGL-1 has to be sialylated to function as a ligand for P-selectin, and the sialyltransferase ST3Gal-IV might play a critical role in this process. We therefore investigated the role of ST3Gal-IV for T-cell development using competitive mixed bone marrow chimeric mice. We found that ST3Gal-IV is dispensable for homing and engraftment of hematopoietic precursors in the bone marrow. However, ST3Gal-IV deficiency affects seeding of the thymus by early T-cell progenitors, leading to impaired restoration of the peripheral T-cell compartment. This defect could be restored by ectopic retroviral expression of ST3Gal-IV in hematopoietic stem cells derived from ST3Gal-IV–deficient donor mice. Our findings show that ST3Gal-IV plays a critical and nonredundant role for efficient T-cell lineage reconstitution after bone marrow transplantation.

Adipose Tissue Hypertrophy, An Aberrant Biochemical Profile and Distinct Gene Expression in Lipedema

BackgroundLipedema is a common adipose tissue disorder affecting women, characterized by a symmetric subcutaneous adipose tissue deposition, particularly of the lower extremities. Lipedema is usually underdiagnosed, thus remaining an undertreated disease. Importantly, no histopathologic or molecular hallmarks exist to clearly diagnose the disease, which is often misinterpreted as obesity or lymphedema. Materials and methodsThe aim of the present study is to characterize in detail morphologic and molecular alterations in the adipose tissue composition of lipedema patients compared with healthy controls. Detailed histopathologic and molecular characterization was performed using lipid and cytokine quantification as well as gene expression arrays. The analysis was conducted on anatomically matched skin and fat tissue biopsies as well as fasting serum probes obtained from 10 lipedema and 11 gender and body mass index–matched control patients. ResultsHistologic evaluation of the adipose tissue showed increased intercellular fibrosis and adipocyte hypertrophy. Serum analysis showed an aberrant lipid metabolism without changes in the circulating adipokines. In an adipogenesis gene array, a distinct gene expression profile associated with macrophages was observed. Histologic assessment of the immune cell infiltrate confirmed the increased presence of macrophages, without changes in the T-cell compartment. ConclusionsLipedema presents a distinguishable disease with typical tissue architecture and aberrant lipid metabolism, different to obesity or lymphedema. The differentially expressed genes and immune cell infiltration profile in lipedema patients further support these findings.

The Regulatory Role of PIRB in CD4+ Th17 Mediated Colitis

Abstract Rationale CD4+T-cell differentiation into effector or memory populations is intrinsically regulated by the delicate balance between activating and inhibitory signals. Previously we identified a role of the inhibitory receptor, Paired Immunoglobulin-like Receptor (PIR) B in the negative regulation of innate immune responses in colitis. The aim of this study is to define the involvement of PIRB in CD4+ Th17 development and regulation of CD4+ Th17-dependent colitis. Results We demonstrate an intrinsic deficiency in PirB−/− Th17 in vitro polarization and cell survival. Specifically, polyclonal activation of PirB−/− Th17 cells lead to increased cell death and enhanced caspase activation (# of Dead cells, WT vs PirB−/−: 17.6 ± 2.3 × 103 vs 38.5 ± 5.8 × 103; # of Caspase 3/7+ cells: 9.8 ± 1.8 × 102 vs 19.7 ± 1.2 × 102; mean ± SEM, p &amp;lt; 0.05). In vivo, PirB−/− Il10−/− mice were protected from development of Il10−/− spontaneous colitis phenotype (Clinical Score, Il10−/− vs PirB−/− Il10−/−: 3.3 ± 0.6 vs 0.14 ± 0.08, p &amp;lt; 0.01; Histological Score: 2.3 ± 0.4 vs 1.2 ± 0.2; mean ± SEM, p &amp;lt; 0.01) and this was associated with reduced CD4+ Th17 cells in the mesenteric lymph nodes (% IL-17a+ cells, Il10−/− vs PirB−/− Il10−/−: 2.5 ± 0.3 vs 1.2 ± 0.1; mean ± SEM, p &amp;lt; 0.001). To test the intrinsic effects to the CD4+ T-cell compartment, we performed the CD4+ CD45RBhi T-cell transfer model of colitis. Rag−/− mice which received PirB−/− naïve CD4+ T-cells were protected from T-cell mediated colitis (% Change in Body Weight: −3.5 ± 4.9 % WT; 20.7 ± 4.6 % PirB−/−; p &amp;lt; 0.001; Histological Score: 3.8 ± 0.2 WT; 1.0 ± 0.4 PirB−/−; mean ± SEM, p &amp;lt; 0.001). Conclusions These data support the concept that PIRB regulates CD4+ Th17 differentiation and development of T-cell-dependent colitis phenotype.

Peptide cargo tunes a network of correlated motions in human leucocyte antigens.

Most biomolecular interactions are typically thought to increase the (local) rigidity of a complex, for example, in drug‐target binding. However, detailed analysis of specific biomolecular complexes can reveal a more subtle interplay between binding and rigidity. Here, we focussed on the human leucocyte antigen (HLA), which plays a crucial role in the adaptive immune system by presenting peptides for recognition by the αβ T‐cell receptor (TCR). The role that the peptide plays in tuning HLA flexibility during TCR recognition is potentially crucial in determining the functional outcome of an immune response, with obvious relevance to the growing list of immunotherapies that target the T‐cell compartment. We have applied high‐pressure/temperature perturbation experiments, combined with molecular dynamics simulations, to explore the drivers that affect molecular flexibility for a series of different peptide–HLA complexes. We find that different peptide sequences affect peptide–HLA flexibility in different ways, with the peptide cargo tuning a network of correlated motions throughout the pHLA complex, including in areas remote from the peptide‐binding interface, in a manner that could influence T‐cell antigen discrimination.