T Cells Research Articles

Prognostic significance of programmed cell death 1 expression on CD8+T cells in various cancers: a systematic review and meta-analysis

BackgroundIncreased PD-1 expression on CD8+ T cells is considered as a hallmark for T-cell exhaustion, and is thought to be related to the prognosis of cancer patients. However, discrepant results have made it difficult to apply PD-1+CD8+T cells and tumor prognosis to clinical practice. Therefore, we conducted a meta-analysis to evaluate its prognostic value in human cancers.MethodsPRISMA reporting guidelines were strictly followed for conducting the current meta-analysis. The PubMed, Web of Science, Embase databases were searched from inception to November 2024. The pooled Hazard Ratio (HR) along with 95% confidence intervals (CIs) of each article were combined for the associations of PD-1+CD8+ T cells with overall survival (OS), progression- free survival (PFS) and disease-free survival(DFS). Subgroup analyses were performed for area, specimen type, cancer type, treatment, detected method and cancer stage.ResultsA total of 20 studies (23 cohorts, 3086 cancer patients) were included in our study. The expression PD-1+CD8+ T cells in cancer patients tended to predict poor overall survival (OS) (HR: 1.379, 95%CI: 1.084-1.753, p= 0.009), and unfavorable disease-free survival(DFS) (HR: 1.468, 95%CI: 0.931-2.316, p=0.099), though it did not reach statistical significance. Begg’s and Egger’s test demonstrated that no obvious publication bias was exist.ConclusionsHigh PD-1 expression on CD8+ T cells is associated with worse survival outcomes, which can be potentially used as a prognostic marker of malignant tumor.

A distinct immunophenotype in children carrying the Blautia enterotype: The generation R study.

Studies in mouse models and human adults have shown that the intestinal microbiota composition can affect peripheral immune cells. We here examined whether the gut microbiota compositions affect B and T-cell subsets in children. The intestinal microbiota was characterized from stool samples of 344 10-year-old children from the Generation R Study by performing 16S rRNA sequencing. Bray-Curtis dissimilarity was used to cluster distinct microbiome compositions (enterotypes). B-cell and T-cell phenotypes were defined by 11-color-flow cytometry. Linear regression models with adjustment for lifestyle and child characteristics were performed to determine associations between enterotypes and immune cell numbers. Three enterotypes with distinct microbiota composition were found, characterized by high abundance of Prevotella, Bacteroides and Blautia. Children with the Blautia enterotype had decreased numbers of plasmablasts, CD4+ central memory (Tcm) T cells and follicular T-helper cells (Tfh), while Th22 cells and CD4+ effector memory (Tem) T cells, CD27-IgA+ memory B cells and CD27-IgE+ memory B cells, were increased in these children. In addition, in children with the Blautia enterotype CD4+ Tcm cell numbers expressing the β7 integrin, which can pair with α4 to mediate intestinal were also lower, while CD4+β7+ Tem cell numbers were higher than in the other enterotypes. The Blautia enterotype showed features beneficial for human health. Enterotypes were associated with differences in memory B- and T-cell compartments. This study is unique in the detailed analysis of the B and T-cell compartment and the intestinal microbiome in a large generic pediatric cohort, enabling correction for child and maternal covariates. These outcomes could guide further studies about the impact of intestinal microbiome intervention, for instance through diet and microbiota metabolites such as short chain fatty acid production.

Heterochromatic gene silencing controls CD4+ T cell susceptibility to regulatory T cell-mediated suppression in a murine allograft model

Protective immune responses require close interactions between conventional (Tconv) and regulatory T cells (Treg). The extracellular mediators and signaling events that regulate the crosstalk between these CD4+ T cell subsets have been extensively characterized. However, how Tconv translate Treg-dependent suppressive signals at the chromatin level remains largely unknown. Here we show, using a murine bone marrow allograft model in which graft rejection is coordinated by CD4+ T cells and can be inhibited by Treg, that Treg-mediated T cell suppression involves Heterochromatin Protein 1 α (HP1α)-dependent gene silencing. Unexpectedly, our screen also reveals that T cells deficient for HP1γ or the methyltransferase SUV39H1 are better repressed by Treg than their wild-type counterparts. Mechanistically, our transcriptional and epigenetic profiling identifies HP1γ as a negative regulator of a gene network functionally associated with T-cell exhaustion, including those encoding the inhibitory receptors PD-1 and LAG-3. In conclusion, we identify HP1 variants as rheostats that finely tune the balance between tolerance and immunity. While HP1α converts immunosuppressive signals into heterochromatin-dependent gene silencing mechanisms, HP1γ adjusts Tconv sensitivity to inhibitory environmental signals.

Polyfunctional CD8+CD226+RUNX2hi effector Tcells are diminished in advanced stages of chronic lymphocytic leukemia.

CD8+ Tcells, a subset of Tcells identified by the surface glycoprotein CD8, particularly those expressing the co-stimulatory molecule CD226, play a crucial role in the immune response to malignancies. However, their role in chronic lymphocytic leukemia (CLL), an immunosuppressive disease, has not yet been explored. We studied 64 CLL patients and 25 age- and sex-matched healthy controls (HCs). We analyzed the proportion of CD226-expressing cells among different CD8+ Tcell subsets (including naïve, central memory, effector memory, and effectors) in CLL patients, stratified by Rai stage and immunoglobulin heavy-chain variable region gene (IgHV) mutation status. Additionally, we compared the effector functions of CD8+CD226+ cells and their CD226- counterparts. We also quantified cytokine and chemokine levels in the plasma of CLL and HCs. Furthermore, we reanalyzed the publicly available bulk RNA-seq on CD226+ and CD226-CD8+ Tcells. Finally, we evaluated the impact of elevated cytokines/chemokines on CD226 expression. Our results showed that CD226-expressing cells were significantly decreased within the effector memory and effector CD8+ Tcell subsets in CLL patients with advanced Rai stages and unmutated IgHV, a marker of poor prognosis. These cells displayed robust effector functions, including cytokine production, cytolytic activity, degranulation, proliferation, and migration capacity. In contrast, CD8+CD226- Tcells displayed an exhausted phenotype with reduced Runt-related transcription factor 2 (RUNX2) expression. Elevated levels of interleukin-6 (IL-6) and macrophage inflammatory protein-1 beta (MIP-1β) were inversely correlated with the frequency of CD8+CD226+ Tcells and may contribute to the downregulation of CD226, possibly leading to Tcell dysfunction in CLL. Our findings highlight the critical role of CD8+CD226+RUNX2hi Tcells in CLL and suggest that their reduction is associated with disease progression and poor clinical outcomes. This study also underscores the potential of targeting IL-6 and MIP-1β to preserve polyfunctional CD8+CD226+ Tcells as a promising immunotherapy strategy.

Convergent and divergent immune aberrations in COVID-19, post-COVID-19-interstitial lung disease, and idiopathic pulmonary fibrosis.

We aimed to study transcriptional and phenotypic changes in circulating immune cells associated with increased risk of mortality in COVID-19, resolution of pulmonary fibrosis in post-COVID-19-interstitial lung disease (ILD), and persistence of idiopathic pulmonary fibrosis (IPF). Whole blood and peripheral blood mononuclear cells (PBMCs) were obtained from 227 subjects with COVID-19, post-COVID-19 interstitial lung disease (ILD), IPF, and controls. We measured a 50-gene signature (nCounter, Nanostring) previously found to be predictive of IPF and COVID-19 mortality along with plasma levels of several biomarkers by Luminex. In addition, we performed single-cell RNA sequencing (scRNA-seq) in PBMCs (10x Genomics) to determine the cellular source of the 50-gene signature. We identified the presence of three genomic risk profiles in COVID-19 based on the 50-gene signature associated with low-, intermediate-, or high-risk of mortality and with significant differences in proinflammatory and profibrotic cytokines. Patients with COVID-19 in the high-risk group had increased expression of seven genes in CD14+HLA-DRlowCD163+ monocytic-myeloid-derived suppressive cells (7Gene-M-MDSCs) and decreased expression of 43 genes in CD4 and CD8 T cell subsets. The loss of 7Gene-M-MDSCs and increased expression of these 43 genes in T cells was seen in survivors with post-COVID-19-ILD. On the contrary, patients with IPF had low expression of the 43 genes in CD4 and CD8 T cells. Collectively, we showed that a 50-gene, high-risk profile, predictive of IPF and COVID-19 mortality is characterized by a genomic imbalance in monocyte and T-cell subsets. This imbalance reverses in survivors with post-COVID-19-ILD highlighting genomic differences between post-COVID-19-ILD and IPF.NEW & NOTEWORTHY Changes in the 50-gene signature, reflective of increase in CD14+HLA-DRlowCD163+ monocytes and decrease in CD4 and CD8 T cells, are associated with increased mortality in COVID-19. A reversal of this pattern can be seen in post-COVID-19-ILD, whereas its persistence can be seen in IPF. Modulating the imbalance between HLA-DRlow monocytes and T cell subsets should be investigated as a potential strategy to treat pulmonary fibrosis associated with severe COVID-19 and progressive IPF.

Mepolizumab in patients with lymphoid variant hypereosinophilic syndrome: a multi-center prospective study.

Hypereosinophilic syndrome (HES) is characterized by blood and tissue hypereosinophilia causing organ damage and/or dysfunction. Mepolizumab, an anti-IL-5 antibody, has recently been approved in this indication. In lymphoid variant (L-)HES, eosinophil expansion is driven by IL-5-producing clonal CD3-CD4+ T cells. This study aimed to elucidate the efficacy of mepolizumab in patients with CD3-CD4+ L-HES, and the impact of treatment on aberrant cells and associated biomarkers. A biomarker sub-study was conducted during two clinical trials evaluating mepolizumab in HES, a 32-week randomized placebo-controlled trial (200622) followed by a 20-week open-label extension (205203). Patients with CD3-CD4+ and/or clonal T cells, elevated serum TARC/CCL17, sCD25 and/or detectable IL-5 were identified, and their treatment responses were compared to those without these anomalies. Of the 108 patients enrolled in 200622-205203, 103 consented to this study, including 17 with a CD3-CD4+ T-cell subset. Presence of CD3-CD4+ T cells or sCD25 levels ≥1500 pg/ml was associated with reduced eosinophil-lowering and corticosteroid-sparing effects of mepolizumab. None of the biomarkers were associated with an increased likelihood of experiencing clinical flares. A mepolizumab-induced increase in serum IL-5 was observed, that was significantly higher in patients with CD3-CD4+ T cells. Treatment did not affect CD3-CD4+ T cell counts. Mepolizumab has a favorable impact on disease flares in patients with CD3-CD4+ L-HES, although reduced eosinophil-depleting and corticosteroid-sparing effects are observed at the currently-approved dose. Further studies are needed to validate these findings on larger patient cohorts, and to explore whether clinical activity other than flares is equally controlled in this disease variant.

The impact of photodynamic therapy on cellular immune function in patients with cervical HPV infection

Cervical Human Papillomavirus (HPV) infection, a common sexually transmitted infection, can lead to cervical cancer. This study investigates the impact of Photodynamic Therapy (PDT) on cellular immune function in cervical HPV-infected patients. From October 2022 to February 2023, 60 patients with cervical HPV infection were randomly assigned to a control group (conventional treatment) or a PDT group (PDT treatment), each with 30 patients. Peripheral blood samples and cervical tissue were collected before treatment, at 3 months, and at 6 months post-treatment. Flow cytometry assessed T-cell subsets (CD4+, CD8+, CD3+), and ELISA measured cytokine levels (TNF-α, IL-6, IL-8). Baseline characteristics were similar between the PDT and control groups. The PDT group showed significantly higher HPV clearance rates at 3-months (70.00 %) and 6 months (100.00 %) compared to the control group 43.33 % and 80.00 %, respectively (p < 0.05). PDT significantly increased CD3+ and CD4+ cell levels at 3- and 6-months post-treatment compared to controls (p < 0.05). CD8+ levels and the CD4+/CD8+ ratio also significantly increased in the PDT group at 6 months. Additionally, PDT significantly reduced IL-6, IL-8, and TNF-α levels at 3- and 6-months post-treatment (p < 0.05). PDT enhances cellular immune function in cervical HPV-infected patients by increasing CD4+ and CD8+ T-cells and reducing pro-inflammatory cytokines. These findings highlight the potential of PDT in modulating immune responses and improving therapeutic strategies for cervical HPV infection.

Control of T-cell immunity by fatty acid metabolism.

Fatty acids play critical roles in maintaining the cellular functions of T cells and regulating T-cell immunity. This review synthesizes current research on the influence of fatty acids on T-cell subsets, including CD8+ T cells, TH1, TH17, Treg (regulatory T cells), and TFH (T follicular helper) cells. Fatty acids impact T cells by modulating signaling pathways, inducing metabolic changes, altering cellular structures, and regulating gene expression epigenetically. These processes affect T-cell activation, differentiation, and function, with implications for diseases such as autoimmune disease and cancer. Based on these insights, fatty acid pathways can potentially be modulated by novel therapeutics, paving the way for novel treatment approaches for immune-mediated disorders and cancer immunotherapy.

Novel Approaches of Cellular Therapy in Multiple Myeloma - Focus on CART.

Recent advancements in cellular therapies, particularly CAR-T and T cell engaging bispecific antibodies have significantly altered the therapeutic landscape for Multiple Myeloma. There are two U.S. FDA approved CAR-T products targeting BCMA available for commercial use at this time. Though these innovative therapies have demonstrated considerable efficacy in heavily pretreated multiple myeloma patients, many challenges remain, including accessibility, potential toxicities such as cytokine release syndrome and neurotoxicity and development of resistance through targeted antigen loss and T-cell exhaustion and various other mechanisms. CRISPR edited allogeneic CAR-T cells, CAR- NK cells, and structural makeover of autologous CART with safety switches are being studied to address current limitations in cellular therapy. Additionally, newer target antigens such as GPRC5D, FcRH5, armored CAR-T cells that resist immunosuppressive cytokines such as TGF-β are being investigated. This review summarizes safety and efficacy of currently available CART, discusses challenges with these therapies, and ongoing research efforts aimed at addressing resistance, mitigate treatment-related toxicities, and refining for broader applicability and prolonged efficacy. CART cell therapy has shown significant benefit in treatment of multiple myeloma. Many challenges persist. Novel strategies with structural modifications are being incorporated to overcome the limitations.

Sex-related differences in the morphology of rectal mucosa-associated lymphoid tissues in C57BL/6NCrSlc mice.

Sex hormones regulate gut function and mucosal immunity; however, their specific effects on the mucosa-associated lymphoid tissue (MALT) in the rectum of mammals remain unclear. Here, we aimed to investigate the influence of sex on MALT in the rectum of mammals by focusing on the rectal mucosa-associated lymphoid tissues (RMALTs) of C57BL/6NCrSIc mice. Histological analysis revealed that RMALTs were predominantly located in the lamina propria and submucosa of the rectal mucosa, with a significant sex-related difference in the distance from the anorectal junction to the first appearance of the RMALT. Despite similar RMALT numbers, females exhibited significantly larger RMALTs than males. Immunostaining revealed the presence of various immune cells, including T cells, B cells, macrophages, proliferative immune cells, lymphatic vessels, and high endothelial venules (HEVs), in RMALTs. Compared with males, females showed elevated T cell, helper T cell, and cytotoxic T-cell gene expression levels, along with high percentages of specific T-cell subsets. The factors influencing RMALT development, such as the presence of HEVs, C-X-C motif chemokine ligand 13 expression, and RMALT-containing cell proliferation, were also explored. Overall, this study revealed the detailed attributes of RMALTs, their immune cell composition, and their determinants in male and female mice, providing insights into the sex-specific characteristics of the rectal mucosal immune system.

Deciphering long-term immune effects of HIV-1/SARS-CoV-2 co-infection: a longitudinal study

IntroductionWhile the general immune response to Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) is well-understood, the long-term effects of Human Immunodeficiency Virus-1/Severe Acute Respiratory Syndrome-Coronavirus-2 (HIV-1/SARS-CoV-2) co-infection on the immune system remain unclear. This study investigates the immune response in people with HIV-1 (PWH) co-infected with SARS-CoV-2 to understand its long-term health consequences.MethodsA retrospective longitudinal study of PWH with suppressed viral load and SARS-CoV-2 infection was conducted. Cryopreserved peripheral blood mononuclear cells and plasma samples were collected at three time-points: HIV-1/pre-SARS-CoV-2 (n = 18), HIV-1/SARS-CoV-2 (n = 46), and HIV-1/post-SARS-CoV-2 (n = 36). Plasma levels of 25 soluble cytokines and chemokines, and anti-S/anti-N-IgG-SARS-CoV-2 antibodies were measured. Immunophenotyping of innate and adaptive immune components and HIV-1 and SARS-CoV-2-specific T/B-cell responses were assessed by flow cytometry.ResultsHIV-1/SARS-CoV-2 co-infection was associated with long-lasting immune dysfunction, characterized by elevated levels of pro-inflammatory cytokines and a decrease in the MIG-IP10-ITAC chemokine axis at the HIV/SARS-CoV-2 time-point, which persisted one year later. Additionally, alterations in the distribution of subsets and increased activation (NKG2D/NKG2C) and maturation (TIM3) markers of NK and dendritic cells were observed at the HIV-1/SARS-CoV-2 time-point, persisting throughout the study. Effector memory CD4 T-cell subsets were decreased, while exhaustion/senescence (PD1/TIM3/CD57) markers were elevated at all three time-points. SARS-CoV-2-specific T/B-cell responses remained stable throughout the study, while HIV-1-specific T-cell responses decreased at the HIV-1/SARS-CoV-2 time-point and remained so.ConclusionsPersistent immune dysfunction in HIV-1/SARS-CoV-2 co-infection increases the risk of future complications, even in PWH with mild symptoms. Exacerbated inflammation and alterations in immune cells may contribute to reduce vaccine efficacy and potential reinfections.

CD8+T Cell Exhaustion and Immune Checkpoint Blockade Treatment

T cells play an important role in anti-tumor immunity. Its subset that contains the surface receptor CD8, also called cytotoxic T cells, functions to facilitate tumor cell elimination. Chronic exposure of CD8+ T cells to antigens and inflammation can cause the T cells to lose their functions as well as changes in their surface expressions, named T cell exhaustion (Tex). This article reviews the molecular mechanisms of this cellular process and the influence of the tumor microenvironment (TME) on it. This article focuses on the mechanism of action of the four major upregulated immune checkpoint proteins (ICPs) and introduces ICB therapies targeting each ICP. Based on these mechanisms, scientists have suggested various interventions to reverse T-cell exhaustion. Recent clinical data show that although ICB therapy has significant efficacy in some patients, its limitations in patient selection limit the popularization of the treatment effect. ICB which curbs Tex by blocking the signal pathways that suppress T cell functions, summarizes the current understandings and progress, and identifies the gaps on this topic.

Single-cell RNA sequencing uncovers heterogenous immune cell responses upon exposure to food additive (E171) titanium dioxide

The prospective use of food additive titanium dioxide (E171 TiO2) in a variety of fields (food, pharmaceutics, and cosmetics) prompts proper cellular cytotoxicity and transcriptomic assessment. Interestingly, smaller-sized E171 TiO2 can translocate in bloodstream and induce a diverse immunological response by activating the immune system, which can be either pro-inflammatory or immune-suppressive. Nevertheless, their cellular or immunologic responses in a heterogeneous population of the immune system following exposure of food additive E171 TiO2 is yet to be elucidated. For this purpose, we have used male Sprague-Dawley rats to deliver E171 TiO2 (5 mg/kg bw per day) via non-invasive intratracheal instillation for 13 weeks. After the 4 weeks recovery period, 3 mL of blood samples from both treated and untreated groups were collected for scRNAseq analysis. Firstly, granulocyte G1 activated innate immune response through the upregulation of genes involved in pro-inflammatory cytokine mediated cytotoxicity. Whereas NK cells resulted in heterogeneity role depending on the subsets where NK1 significantly inhibited cytotoxicity, whereas NK2 and NK3 subsets activated pro-B cell population & inhibited T cell mediated cytotoxicity respectively. While NKT_1 activated innate inflammatory responses which was confirmed by cytotoxic CD8+ T killer cell suppression. Similarly, NKT_2 cells promote inflammatory response by releasing lytic granules and MHC-I complex inhibition to arrest cytotoxic T killer cell responses. Conversely, NKT_3 suppressed inflammatory response by release of anti-inflammatory cytokines suggesting the functional heterogeneity of NKT subset. The formation of MHC-I or MHC-II complexes with T-cell subsets resulted in neither B and T cell dysfunction nor cytotoxic T killer cell inhibition suppressing adaptive immune response. Overall, our research offers an innovative high-dimensional approach to reveal immunological and transcriptomic responses of each cell types at the single cell level in a complex heterogeneous cellular environment by reassuring a precise assessment of immunological response of E171 TiO2.Graphical

Differential Control of T-Cell Subsets by Recombinant Human PLD2 in a Mouse Model of Allergic Asthma

ABSTRACT Background Phospholipase D2 (PLD2) enzymes are expressed on the cytoplasmic membrane of bacteria, fungi, plants, and animals. Recently, extensive research has linked PLD2 to the chronic inflammatory activity of cells. Allergic asthma is a chronic airway inflammation disease. In this context, a recombinant human phospholipase D2 (rhPLD2) was designed and modified from the wild-type PLD2 to study its effects in an ovalbumin (OVA) induced murine model of asthma. Methods Hematoxylin and eosin staining was used for lung histopathology. Cytokine concentrations in bronchoalveolar lavage fluid (BALF) were measured using ELISA kits. The ratio of T-bet and GATA-3 expression level in spleen and lymph nodes following rhPLD2 administration was assessed through RT-PCR. Phenotyping analysis of Treg cells from peripheral blood was performed by flow cytometry. Results It indicated that OVA-induced mice exhibited elevated pulmonary eosinophilia and allergic inflammation in the airways, along with increased expression of IFN-γ, IL-4 in the lung BALF. Administration of rhPLD2 alleviated lung inflammation and significantly reduce the number of eosinophils in peripheral blood and BALF. RhPLD2 also reversed the IFN-γ/IL-4 ratio at the molecular level in BALF and the T-bet/GATA-3 ratio in lymphocytes of the lung, spleen, lymph nodes at the genetic level. Furthermore, FACS analysis demonstrated that rhPLD2 increased the frequency of both IL-10+Treg cells and CD25+ Treg cells. Conclusion From a therapeutic perspective, rhPLD2 alleviates allergic airway inflammation by balancing Th1/Th2 homeostasis and increasing Treg cells. It has been shown to function in immunoregulatory activities in OVA-induced asthma mice.

Microenvironmental Traits of Classical Hodgkin's Lymphoma in Adolescents and Their Prognostic Impact.

Classical Hodgkin's lymphoma (cHL) in adolescents between 15 and 18 years old shows a higher disease-related mortality, and the overall prognosis is worse than in both children and adults. We investigated the immune checkpoint inhibitors (ICPIs) therapeutic targets and specific T-regulatory and cytotoxic T-cell subsets in the subgroup of adolescent cHL patients, and we challenged their prognostic power. We retrieved formalin-fixed paraffin-embedded (FFPE) tissue of adolescent patients diagnosed with cHL and tested by immunohistochemistry the immune checkpoint molecules CTLA-4, LAG-3, PD-1, and PDL1 as well as the biological markers FOXP3 and CD8. All the cases of our cohort expressed the immune checkpoint molecules CTLA-4, LAG-3, and PD-1 in microenvironment (ME), and the number of PD1+ cells was strongly associated with advanced disease, being higher in stage III/IV, indicating a possible role in the progression of cHL. A higher risk of recurrence and progression occurred in patients with lower amount of CD8+ microenvironmental T-cells at diagnosis (67.14 ± 27.23 vs. 42.86 ± 17.33 p = 0.032 and 65.59 ± 26.68 vs. 37 ± 17.45 p = 0.046, respectively). We showed that microenvironment of cHL in adolescent patients is enriched with potential therapeutic targets of ICPI that may be considered for therapeutic applications. Furthermore, the presence of PD-1 expressing T-cells strongly relates to advanced stage disease and a low density of CD8+ T lymphocytes is associated with recurrence and progression of disease.

Multiomic profiling of chronically activated CD4+ T cells identifies drivers of exhaustion and metabolic reprogramming.

Repeated antigen exposure leads to T-cell exhaustion, a transcriptionally and epigenetically distinct cellular state marked by loss of effector functions (e.g., cytotoxicity, cytokine production/release), up-regulation of inhibitory receptors (e.g., PD-1), and reduced proliferative capacity. Molecular pathways underlying T-cell exhaustion have been defined for CD8+ cytotoxic T cells, but which factors drive exhaustion in CD4+ T cells, that are also required for an effective immune response against a tumor or infection, remains unclear. Here, we utilize quantitative proteomic, phosphoproteomic, and metabolomic analyses to characterize the molecular basis of the dysfunctional cell state induced by chronic stimulation of CD4+ memory T cells. We identified a dynamic response encompassing both known and novel up-regulated cell surface receptors, as well as dozens of unexpected transcriptional regulators. Integrated causal network analysis of our combined data predicts the histone acetyltransferase p300 as a driver of aspects of this phenotype following chronic stimulation, which we confirmed via targeted small molecule inhibition. While our integrative analysis also revealed large-scale metabolic reprogramming, our independent investigation confirmed a global remodeling away from glycolysis to a dysfunctional fatty acid oxidation-based metabolism coincident with oxidative stress. Overall, these data provide both insights into the mechanistic basis of CD4+ T-cell exhaustion and serve as a valuable resource for future interventional studies aimed at modulating T-cell dysfunction.

TOX Does Not Drive Sepsis-Induced T-Cell Exhaustion.

The immune system undergoes profound dysregulation in sepsis, characterized by hyperinflammation in the acute phase followed by long-lasting immunosuppression. T-cell exhaustion has been proposed as one facet of sepsis-related immunosuppression, which is characterized by impaired effector function and continuous expression of PD1. However, the current analysis of T-cell exhaustion in the post-sepsis is inadequate. Our current study has identified a progressive increase in the frequency of CD44+CD11a+ memory T cells during the post-sepsis phase, accompanied by the upregulation of exhaustion markers (PD-1, Lag3, and Tim3) and functional impairments in these cells. TOX is traditionally recognized as a key regulator driving CD8+ T-cell exhaustion in cancer and chronic infection. However, we demonstrate that TOX does not play a critical role in T-cell exhaustion during chronic sepsis but rather is involved in T-cell effector function. Both knockout and "knockdown" of TOX failed to alleviate sepsis-induced T-cell exhaustion. Instead, deletion of TOX impaired the effector function of T cells in chronic sepsis, contradicting its impact on short-term TCR engagement. Our study provides a novel insight into sepsis-induced T-cell exhaustion, highlighting the distinct characteristics of T-cell exhaustion programmed by sepsis.

The Evolving Applications of Bispecific Antibodies: Reaping the Harvest of Early Sowing and Planting New Seeds.

After decades of gradual progress from conceptualization to early clinical trials (1960-2000), the therapeutic potential of bispecific antibodies (bisp Abs) is now being fully realized. Insights gained from both successful and unsuccessful trials are helping to identify which mechanisms of action, antibody formats, and targets prove most effective, and which may benefit from further refinement. While T-cell engagers remain the most commonly used class of bisp Abs, current efforts aim to increase their effectiveness by co-engaging costimulatory molecules, reducing escape mechanisms, and countering immunosuppression. Strategies to minimize cytokine release syndrome (CRS) are also actively under development. In addition, novel antibody formats that are selectively activated within tumors are an exciting area of research, as is the precise targeting of specific T-cell subsets. Beyond T cells, the recruitment of macrophages and dendritic cells is attracting increasing interest, with researchers exploring various macrophage receptors to promote phagocytosis or to carry out specialized functions, such as the immunologically silent clearance of amyloid-beta plaques in the brain. While bisp Abs targeting B cells are relatively limited, they are primarily aimed at inhibiting B-cell activity in autoimmune diseases. Another evolving application involves the forced interaction between proteins. Beyond the successful development of Hemlibra for hemophilia, bispecific antibodies that mimic cytokine activity are being explored. Additionally, the recruitment of cell surface ubiquitin ligases and other enzymes represents a novel and promising therapeutic strategy. In regard to antibody formats, some applications such as the combination of T-cell engagers with costimulatory molecules are driving the development of trispecific antibodies, at least in preclinical settings. However, the increasing structural complexity of multispecific antibodies often leads to more challenging development paths, and the number of multispecific antibodies in clinical trials remains low. The clinical success of certain applications and well-established production methods position this therapeutic class to expand its benefits into other therapeutic areas.

Polycytotoxic T cells mediate antimicrobial activity against intracellular Mycobacterium tuberculosis.

Protection against infections with intracellular bacteria requires the interaction of macrophages and T-lymphocytes, including CD8+ T cells. Recently, the expression of natural killer cell receptors NKG2A and NKG2C was introduced as markers of CD8+ T-cell subsets. The goal of this study was to functionally characterize human NKG2A and NKG2C-expressing T cells using the major pathogen Mycobacterium tuberculosis (Mtb) as a model organism. Sorted NKG2 populations were analyzed for their capacity to proliferate and degranulate and their intracellular expression of cytotoxic molecules. Cytokine release and the effect on bacterial growth were assessed after coculture of NKG2 populations with Mtb-infected macrophages. NKG2A+ T cells released higher levels of IFN-γ and IL-10, whereas NKG2C+ T cells released higher levels of IL-2, contained the greatest reservoir of intracellular granzyme B and showed a remarkable constitutive level of degranulation. Both subsets inhibited the intracellular growth of Mtb more efficiently than NKG2-negative CD8+ T cells. Antimicrobial activity of NKG2+ T cells was not associated with the release of cytokines or cytotoxic molecules. However, the frequency of polycytotoxic T cells (P-CTL), defined as CD8+ T cells co-expressing granzyme B, perforin, and granulysin, positively correlated with the ability of NKG2-expressing T cells to control Mtb-growth in macrophages. Our results highlight the potential of NKG2-expressing P-CTL to trigger the antibacterial activity of human macrophages. Targeting this population by preventive or therapeutic immune interventions could provide a novel strategy to combat severe infectious diseases such as tuberculosis.

Itaconate Ameliorates Experimental Autoimmune Uveitis by Modulating Teff/Treg Cell Imbalance Via the DNAJA1/CDC45 Axis.

The aim of this study was to elucidate the effect of itaconate (ITA) on experimental autoimmune uveitis (EAU), to explore its potential mechanism, and to identify potential therapeutic targets. We established an animal model of EAU by constructing an immune map of mice treated with ITA and exploring the therapeutic mechanism of ITA by single-cell RNA sequencing and flow cytometry. ITA mitigated ocular inflammation associated with EAU and reversed the pathogenic differentiation linked to Th17 induction by EAU, along with the reactive oxygen species (ROS) and oxidative stress pathways. Subsequent to ITA intervention, the downregulated differentially expressed genes in the T-cell subset primarily centered around the heat shock protein (HSP) family. Activation of HSPs reversed the anti-inflammatory effects of ITA in EAU mice. ITA decreased ROS levels and HSP expression in CD4+ T cells, with DnaJ heat shock protein family (HSP40) member A1 (DNAJA1) exhibiting the most notable alterations among the HSPs. ITA suppressed the expression of DNAJA1/cell division cycle protein 45 (CDC45), thereby disrupting the pathogenic division cycle of CD4+ T cells and reducing their proliferation. Inhibiting DNAJA1 also held promise for modulating the Th17/Treg imbalance. Notably, ITA curtailed the expansion of CD4+ T cells in uveitis patients. Our research delved into the potential therapeutic mechanisms underlying ITA therapy in EAU, offering fresh perspectives on its utility in the treatment of autoimmune conditions. DNAJA1 emerges as a promising candidate for targeted therapeutic interventions in uveitis.