Deficient CD4 Research Articles

4E-BP3 deficiency impairs dendritic cell activation and CD4+ T cell differentiation and attenuates α-myosin-specific T cell-mediated myocarditis in mice.

Immune checkpoint inhibitor (ICI)-associated myocarditis is a rare but potentially fatal immune-related adverse event. Previously, we reported a case of ICI-associated myocarditis with elevated autoantibodies to 4E-binding protein 3 (4E-BP3). Recent studies have suggested that 4E-BP3 may play an important role in tumor development. However, its role in cardiac diseases including myocarditis is unknown. We investigated the role of 4E-BP3 in an autoimmune myocarditis mouse model. Myocarditis was induced in wild-type and 4E-BP3 knockout mice by immunization with murine α-myosin peptide. 4E-BP3 gene expression was upregulated in the heart of myocarditis mouse. We found that genetic deletion of 4E-BP3 attenuated myocardial inflammation, reduced fibrosis area, and improved cardiac function in myocarditis mice. Studies in bone marrow-chimeric mice demonstrated that immune cell-derived 4E-BP3 plays a pivotal role in the pathogenesis of myocarditis. Immune cell transfer experiments revealed that 4E-BP3 deficiency in dendritic cells and CD4+ T cells decreased disease severity in recipient mice. Furthermore, dendritic cells that were deficient in 4E-BP3 exhibited a diminished capacity to produce IL-6 and IL-1β. Naive CD4+ T cells lacking 4E-BP3 had a reduced ability to differentiate into T-helper (Th)1 and Th17 cells. These findings suggest that 4E-BP3 in dendritic cells and CD4+ T cells may be critically involved in the pathogenesis of α-myosin-specific T cell-mediated myocarditis. Thus, 4E-BP3 could be a possible therapeutic target for myocarditis.

NFATc1 in CD4+ T cells and CD11c+ dendritic cells drives TH2-mediated eosinophilic inflammation in allergic asthma

BackgroundAsthma, a chronic lung disease, is a significant public health problem worldwide. It is marked by increased Th2 response resulting in eosinophil accumulation. The pathophysiology of asthma involves various cell types, including epithelial cells, dendritic cells (DCs), innate lymphoid cells (ILCs), B cells, and effector cells. Nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1), a critical transcription factor for immune regulation, is known for its role in T cells and, more recently, in myeloid cells. However, the specific contributions of NFATc1 in T cells and DCs in the context of asthma are not well understood. ObjectiveExplore NFATc1’s role in T cells and dendritic cells in modulating Th2 immune responses within the pathophysiology of allergic asthma. MethodsMice lacking Nfatc1 in CD4+T cells or CD11c+ dendritic cells, were induced with asthma using house dust mite (HDM), enabling investigation into NFATc1's role in both cell types in experimental allergic asthma. Additionally, the study examined NFATc1 expression in these cells and its correlation with blood eosinophil levels in an adult asthma cohort. ResultsIn HDM-induced asthma model, we found that Nfatc1 deficiency either in CD4+ T cells or CD11c+ dendritic cells resulted in reduced Th2-driven eosinophilic inflammation, immunoglobulin E (IgE) levels, and mast cell presence in the lung of asthmatic mice. Nfatc1's absence in CD4+ T cells directly hampered Th2 cell polarization and functionality, whereas in CD11c+ dendritic cells, it affected DC differentiation and maturation, thereby weakening T cell priming, proliferation and subsequent Th2 differentiation. Correspondingly, translational research indicated significant correlations between CD4+NFATc1+ and CD11c+NFATc1+ cell populations and eosinophil levels in asthmatic patients, but not in healthy controls. ConclusionNFATc1 in T cells and dendritic cells modulate Th2-mediated eosinophilic inflammation in allergic asthma, which offering insights into asthma pathogenesis and identifying NFATc1 as a potential target for therapeutic intervention.

CD226 implicated in Akt-dependent apoptosis of CD4+ T cell contributes to asthmatic pathogenesis.

Asthma is a chronic airway inflammatory disease in which CD4+ T cell dysregulation occurs. Here, we investigated the molecular role and clinical significance of CD226, a costimulatory molecule of T lymphocytes, in the development of allergic asthma. Our results revealed that the expression of CD226 was significantly increased in CD4+ effector T cells, especially in T helper (Th) 2 cells and Th17 cells in patients with asthma. Moreover, CD4+ T cell-specific Cd226-knockout mice were generated and together with littermates were challenged with ovalbumin (OVA) to establish a model of allergic asthma. We found that CD226 deficiency in CD4+ T cells mitigated lung inflammation, IgE production, and eosinophil infiltration and reduced airway remodeling in experimental allergic asthma. However, the impact of CD226 on asthma was independent of Treg cell modulation. Through RNA-seq data analysis, the apoptosis pathway was screened. Mechanistically, CD226 deletion promoted CD4+ T cell late apoptosis via the activation of Caspase-3 in an Akt-dependent manner. Furthermore, blocking CD226 signaling with a recombinant fusion protein attenuated asthma features in mice and achieved a good therapeutic effect. Overall, this study revealed a unique role of CD226 in CD4+ T cell regulation in asthma pathogenesis. Therefore, targeting CD226 may provide new insights into the clinical treatment of asthma.

IFN-γ induces acute graft-versus-host disease by promoting HMGB1-mediated nuclear-to-cytoplasm translocation and autophagic degradation of p53.

Acute graft-versus-host disease (aGVHD) poses a significant impediment to achieving a more favourable therapeutic outcome in allogeneic hematopoietic stem cell transplantation (allo-HSCT). Our prior investigations disclosed a correlation between p53 down-regulation in CD4+ T cells and the occurrence of aGVHD. Notably, the insufficiency of the CCCTC-binding factor (CTCF) emerged as a pivotal factor in repressing p53 expression. However, the existence of additional mechanisms contributing to the reduction in p53 expression remains unclear. Interferon (IFN)-γ, a pivotal proinflammatory cytokine, assumes a crucial role in regulating alloreactive T-cell responses and plays a complex part in aGVHD development. IFN-γ has the capacity to induce autophagy, a vital catabolic process facilitating protein degradation, in various cell types. Presently, whether IFN-γ participates in the development of aGVHD by instigating the autophagic degradation of p53 in CD4+ T cells remains an unresolved question. In the present study, we demonstrated that heightened levels of IFN-γ in the plasma during aGVHD promoted the activation, proliferation, and autophagic activity of CD4+ T cells. Furthermore, IFN-γ induced the nuclear-to-cytoplasm translocation and autophagy-dependent degradation of p53 in CD4+ T cells. The translocation and autophagic degradation of p53 were contingent upon HMGB1, which underwent up-regulation and translocation from the nucleus to the cytoplasm following IFN-γ stimulation. In conclusion, our data unveil a novel mechanism underlying p53 deficiency in CD4+ T cells among aGVHD patients. This deficiency is induced by IFN-γ and relies on autophagy, establishing a link between IFN-γ, HMGB1-mediated translocation, and the autophagic degradation of p53.

Reduced function of the adaptor SH2B3 promotes T1D via altered gc cytokine-regulated, T cell intrinsic immune tolerance.

The rs3184504 polymorphism, encoding a hypomorphic variant of the negative regulator SH2B3, strongly associates with T1D.SH2B3 deficiency results in hypersensitivity to cytokines, including IL-2, in murine CD4+ and CD8+ T cells.SH2B3 deficient CD8+ T cells exhibit a comparable transcriptome to wild-type CD8+ T cells at baseline, but upon antigen stimulation SH2B3 deficient cells upregulate genes characteristic of enhanced JAK/STAT signaling and effector functions.We found a T-cell intrinsic role of SH2B3 leading to severe islet destruction in an adoptive transfer murine T1D model, while global SH2B3 deficiency accelerated spontaneous NOD diabetes across sexes.

Hypocortisolemic ASIA: a vaccine- and chronic infection-induced syndrome behind the origin of long COVID and myalgic encephalomyelitis.

Myalgic encephalomyelitis or chronic fatigue syndrome (ME/CFS), long COVID (LC) and post-COVID-19 vaccine syndrome show similarities in their pathophysiology and clinical manifestations. These disorders are related to viral or adjuvant persistence, immunological alterations, autoimmune diseases and hormonal imbalances. A developmental model is postulated that involves the interaction between immune hyperactivation, autoimmune hypophysitis or pituitary hypophysitis, and immune depletion. This process might begin with a deficient CD4 T-cell response to viral infections in genetically predisposed individuals (HLA-DRB1), followed by an uncontrolled immune response with CD8 T-cell hyperactivation and elevated antibody production, some of which may be directed against autoantigens, which can trigger autoimmune hypophysitis or direct damage to the pituitary, resulting in decreased production of pituitary hormones, such as ACTH. As the disease progresses, prolonged exposure to viral antigens can lead to exhaustion of the immune system, exacerbating symptoms and pathology. It is suggested that these disorders could be included in the autoimmune/adjuvant-induced inflammatory syndrome (ASIA) because of their similar clinical manifestations and possible relationship to genetic factors, such as polymorphisms in the HLA-DRB1 gene. In addition, it is proposed that treatment with antivirals, corticosteroids/ginseng, antioxidants, and metabolic precursors could improve symptoms by modulating the immune response, pituitary function, inflammation and oxidative stress. Therefore, the purpose of this review is to suggest a possible autoimmune origin against the adenohypophysis and a possible improvement of symptoms after treatment with corticosteroid replacement therapy.

Effect of photobiomodulation in the balance between effector and regulatory T cells in an experimental model of COPD.

Currently, Chronic Obstructive Pulmonary Disease (COPD) has a high impact on morbidity and mortality worldwide. The increase of CD4+, CD8+ cells expressing NF-κB, STAT4, IFN-γ and perforin are related to smoking habit, smoking history, airflow rate, obstruction and pulmonary emphysema. Furthermore, a deficiency in CD4+CD25+Foxp3+ regulatory T cells (Tregs) may impair the normal function of the immune system and lead to respiratory immune disease. On the other hand, the anti-inflammatory cytokine IL-10, produced by Treg cells and macrophages, inhibits the synthesis of several pro-inflammatory cytokines that are expressed in COPD. Therefore, immunotherapeutic strategies, such as Photobiomodulation (PBM), aim to regulate the levels of cytokines, chemokines and transcription factors in COPD. Consequently, the objective of this study was to evaluate CD4+STAT4 and CD4+CD25+Foxp3+ cells as well as the production of CD4+IFN- γ and CD4+CD25+IL-10 in the lung after PBM therapy in a COPD mice model. We induced COPD in C57BL/6 mice through an orotracheal application of cigarette smoke extract. PMB treatment was applied for the entire 7 weeks and Bronchoalveolar lavage (BAL) and lungs were collected to study production of IFN- γ and IL-10 in the lung. After the last administration with cigarette smoke extract (end of 7 weeks), 24 h later, the animals were euthanized. One-way ANOVA followed by NewmanKeuls test were used for statistical analysis with significance levels adjusted to 5% (p < 0.05). This result showed that PBM improves COPD symptomatology, reducing the number of inflammatory cells (macrophages, neutrophils and lymphocytes), the levels of IFN-γ among others, and increased IL-10. We also observed a decrease of collagen, mucus, bronchoconstriction index, alveolar enlargement, CD4+, CD8+, CD4+STAT4+, and CD4+IFN-γ+ cells. In addition, in the treated group, we found an increase in CD4+CD25+Foxp3+ and CD4+IL-10+ T cells. This study suggests that PBM treatment could be applied as an immunotherapeutic strategy for COPD.

Effect of BCL9/BCL9L inhibition–derived Th1 cells on dendritic cells–mediated antigen presentation in hepatocellular carcinoma and on the efficacy of CAR-T immunotherapy.

e16180 Background: Hepatocellular carcinoma (HCC) is an aggressive malignancy with limited treatment options. The emerging field of tumor immunotherapy, primarily focusing on CD8+ T cells and the tumor microenvironment (TME), has garnered substantial attention. CD4+ T cells, on the other hand, play a crucial role in maintaining immune equilibrium and orchestrating immune responses through interactions with various cell types. As crucial participants and coordinators in innate and adaptive immune responses, the role of CD4+ T cells in tumor development remain further exploration. Conventional dendritic cells (cDCs) are thought to perform antigen presentation to prime CD4+ T cells or CD8+ T cells. However, the reverse regulatory impact of CD4+ T cells on cDCs remains poorly understood. Methods: Initially, we examined the role of CD4+ T cell subsets in HCC development using TCGA database. Subsequently, we established Cd4-Cre Bcl9fl/fl Bcl9lfl/fl mice to explore the impact of T cell-specific Bcl9/Bcl9l deficiency on HCC development. We further investigate the impact of Bcl9/Bcl9l deficiency in CD4+ T cells on the therapeutic efficacy of mouse CAR-T treatment. Moreover, using single-cell RNA sequencing (scRNA-seq) databases from Bcl9/Bcl9l KO tumor-bearing mice and HCC patients, we investigated the regulatory role of CD4+ T cells on the function of cDCs. Finally, we validated the mechanism by which CD4+ T cells regulate cDCs function in a mouse HCC model and explored their influence on tumor-specific CD8+ T cells response. Results: We found elevated Th1 cell infiltration in various cancers including liver hepatocellular carcinoma (LIHC). High Th1 infiltration is associated with a favorable prognosis in LIHC, but there is a significant negative correlation between the expression of B-cell lymphoma 9/B-cell lymphoma 9-like (BCL9/BCL9L) and the infiltration of Th1 cells. We found that blocking T cell-intrinsic BCL9/BCL9L increased frequencies of Th1 cells, thereby suppressing HCC tumor growth. The enrichment of Th1 cells inversely regulates innate immune response to augment cDCs activation. BCL9/BCL9L inhibition amplifies CD4+ T cell and cDCs crosstalk and promotes cDCs antigen presentation. The reinforced cross-presentation of tumor antigens by cDCs promotes activation and proliferation of CD8+ T cells. Moreover, genetic editing of BCL9/BCL9L in CD4+ T cells can enhance the anti-tumor immunity by promoting CAR-T cell toxicity. Conclusions: Thus, BCL9/BCL9L inhibition orchestrate an adaptive immune to innate immune circuit wherein Th1 cells triggers cDCs antigen presentation in turn activate tumor-specific CD8+ T cells response to promote cancer immunity.

Elucidating the Transcriptional Role of the Nuclear Receptor RORα in CD8+ T Cell Memory vs Effector Cell Development

Abstract CD8+ T cells play a critical role in controlling viral infections and cancer and have the potential to be harnessed for the development of new therapeutic strategies. Defining the transcriptional regulatory networks that control CD8+ T cell differentiation and function is of great importance to achieve these goals. The retinoic acid receptor-related orphan receptor alpha (RORα), a member of the nuclear receptor superfamily of ligand-regulated transcription factors, has emerged as a potential transcriptional regulator of CD8+ T cell immunity. However, exactly how RORα functions in these processes is poorly understood. To this end we seek to identify the transcriptional role of RORα in regulating the differentiation of memory CD8+ T cells. Utilizing a mouse model with T cell-specific deletion of RORα we identify that RORα deficiency in CD8+ T cells leads to increased IFNγ production and increased cell-specific cytolytic function in vitro. Conversely, RORα overexpression results in decreased IFNγ production and defects in proliferative capacity in vitro. Our in vivo data further reveals that deletion of RORα in CD8+ T cells may affect the trafficking of these cells to non-lymphoid tissue and play a role in the development of tissue resident memory (TRM) cells. Our study provides important insights into the role of RORα in regulating CD8+ T cell function and highlights the potential for targeting nuclear receptors in the development of novel cell-based therapeutics.

Sustained cross-talk between donor T cells and IL-33+ stromal cells maintains CD4 T cell differentiation and determines GVHD outcomes

Abstract Conditioning before allogeneic hematopoietic stem cell transplantation (AlloHSCT) increases the tissue injury signal IL-33 in fibroblastic reticular cells (FRC). Released IL-33 directly stimulates donor CD4 T cells to prime IL-12-independent Type 1 T helper cell (Th1) differentiation and expansion. Tissue stroma upregulates IL-33, but a role for IL-33 in sustaining the pathogenic donor Th1 responses causing GVHD is unclear. We compared B6 mice with inducible ST2 deletion (R26-CreERT2xSt2fl/fl) to wildtype (WT) R26-CreERT2 as T cell donors in a lethal GVHD model (B6 to BALB/c). Donor ST2 deletion at days 10-14 post AlloHSCT increased CD4 T cells Foxp3 expression with reciprocal decreases in Tbet expression in both the lymphoid organs and target tissues. Sustained IL-33 signaling also maintained donor T cell TCF1 expression. Ablating ST2 after GVHD development improved clinical scores and promoted recipient weight gain. How bioactive IL-33 is released from nuclear sequestration remains undefined. RNAseq analysis suggested that IL-33 stimulates T cell granzyme B (GzmB) expression and B6 GzmB deficient (Gzmb-/-) donor T cells displayed reduced activation and expansion similar to ST2 deficient CD4 T cells. In contrast to GzmBWT, anti-IL-33 antibodies had no impact on GzmBKO T cell responses. Thus, cross-talk between donor T cells and IL-33+ stroma orchestrates the T cell identities that are critical to sustain the pathogenic CD4 T cell responses causing GVHD.

Loss of UCP2 in CD4+ T cell promotes Th1/2 Pathogenic Phenotype

Abstract Uncoupling protein 2 (UCP2) is an anion carrier protein located in the mitochondrial inner membrane. Mitochondria are the major sites for energy metabolism which is tightly linked with immune cell fate. In the present study, we have investigated UCP2’s function in T cells against murine melanoma model and the experimental autoimmune encephalomyelitis (EAE) model. Loss of UCP2 in CD4+ T cells showed a significant rise in the Th2/Th1 ratio. These cells exhibited an improved Th2 phenotype with increased production of nitric oxide (NO), and Inducible nitric oxide synthase (iNOS). Therefore, CD4+ T cells were treated with NOC-18, a source of NO, or L-NMMA, inhibitor for NOS to demonstrate NO-mediated Th2 polarization. Furthermore, Treatment of Ucp2 siRNA or, Genipin (inhibitor for UCP2) mimicked the effect of UCP2-/- CD4+ T cell with more cytotoxic markers and Th2/Th1 double positive cells. Transcriptomic and metabolomic analysis revealed the lower response of calcium influx by TCR activation and increased NLRF3 activation by uric acid in UCP2 deficient CD4+ T cells. Adoptive transfer of Genipin-treated Tyrp CD4+ cells exhibited superior tumor control as compared to Th1 and Th2, according to the findings. However, in UCP2-/- mice, the severity of EAE worsened, and heterogenic Th2 cells were infiltrated into the spinal cord. Our findings imply that the loss of UCP2 in CD4 increases Th2 polarization with a cytotoxic phenotype and may be relevant to various illnesses.

123 Helper T cell immunity in humans with inherited CD4 deficiency

123 Helper T cell immunity in humans with inherited CD4 deficiency

SIRT3 Negatively Regulates TFH-Cell Differentiation in Cancer.

Follicular helper T (TFH) cells are essential for inducing germinal center (GC) reactions to mediate humoral adaptive immunity in tumors; however, the mechanisms underlying TFH-cell differentiation remain unclear. In this study, we found that the metabolism sensor sirtuin 3 (SIRT3) is critical for TFH-cell differentiation and GC formation during tumor development and viral infection. SIRT3 deficiency in CD4+ T cells intrinsically enhanced TFH-cell differentiation and GC reactions during tumor development and viral infection. Mechanistically, damaged oxidative phosphorylation (OXPHOS) compensatively triggered the NAD+-glycolysis pathway to provide a cellular energy supply, which was necessary for SIRT3 deficiency-induced TFH-cell differentiation. Blocking NAD+ synthesis-glycolysis signaling or recovering OXPHOS activities reversed the TFH-cell differentiation induced by SIRT3 deficiency. Moreover, the mTOR and hypoxia-inducible factor 1α (HIF1α) signaling axis was found to be responsible for TFH-cell differentiation induced by SIRT3 deficiency. HIF1α directly interacted with and regulated the activity of the transcription factor Bcl6. Thus, our findings identify a cellular energy compensatory mechanism, regulated by the mitochondrial sensor SIRT3, that triggers NAD+-dependent glycolysis during mitochondrial OXPHOS injuries and an mTOR-HIF1α-Bcl6 pathway to reprogram TFH-cell differentiation. These data have implications for future cancer immunotherapy research targeting SIRT3 in T cells.

Cancer SLC6A6-mediated taurine uptake transactivates immune checkpoint genes and induces exhaustion in CD8+ T cells

Taurine is used to bolster immunity, but its effects on antitumor immunity are unclear. Here, we report that cancer-related taurine consumption causes Tcell exhaustion and tumor progression. The taurine transporter SLC6A6 is correlated with aggressiveness and poor outcomes in multiple cancers. SLC6A6-mediated taurine uptake promotes the malignant behaviors of tumor cells but also increases the survival and effector function of CD8+ Tcells. Tumor cells outcompete CD8+ Tcells for taurine by overexpressing SLC6A6, which induces Tcell death and malfunction, thereby fueling tumor progression. Mechanistically, taurine deficiency in CD8+ Tcells increases ER stress, promoting ATF4 transcription in a PERK-JAK1-STAT3 signaling-dependent manner. Increased ATF4 transactivates multiple immune checkpoint genes and induces Tcell exhaustion. In gastric cancer, we identify a chemotherapy-induced SP1-SLC6A6 regulatory axis. Our findings suggest that tumoral-SLC6A6-mediated taurine deficiency promotes immune evasion and that taurine supplementation reinvigorates exhausted CD8+ Tcells and increases the efficacy of cancer therapies.

Helper T cell immunity in humans with inherited CD4 deficiency.

CD4+ T cells are vital for host defense and immune regulation. However, the fundamental role of CD4 itself remains enigmatic. We report seven patients aged 5-61 years from five families of four ancestries with autosomal recessive CD4 deficiency and a range of infections, including recalcitrant warts and Whipple's disease. All patients are homozygous for rare deleterious CD4 variants impacting expression of the canonical CD4 isoform. A shorter expressed isoform that interacts with LCK, but not HLA class II, is affected by only one variant. All patients lack CD4+ T cells and have increased numbers of TCRαβ+CD4-CD8- T cells, which phenotypically and transcriptionally resemble conventional Th cells. Finally, patient CD4-CD8- αβ T cells exhibit intact responses to HLA class II-restricted antigens and promote B cell differentiation in vitro. Thus, compensatory development of Th cells enables patients with inherited CD4 deficiency to acquire effective cellular and humoral immunity against an unexpectedly large range of pathogens. Nevertheless, CD4 is indispensable for protective immunity against at least human papillomaviruses and Trophyrema whipplei.

CD4+ and CD8+ T cells reduce inflammation and promote bone healing in response to titanium implants

T cells are adaptive immune cells essential in pathogenic response, cancer, and autoimmune disorders. During the integration of biomaterials with host tissue, T cells modify the local inflammatory environment by releasing cytokines that promote inflammatory resolution following implantation. T cells are vital for the modulation of innate immune cells, recruitment and proliferation of mesenchymal stem cells (MSCs), and formation of functional tissue around the biomaterial implant. We have demonstrated that deficiency of αβ T cells promotes macrophage polarization towards a pro-inflammatory phenotype and attenuates MSC recruitment and proliferation in vitro and in vivo. The goal of this study was to understand how CD4+ and CD8+ T cells, subsets of the αβ T cell family, impact the inflammatory response to titanium (Ti) biomaterials. Deficiency of either CD4+ or CD8+ T cells increased the proportion of pro-inflammatory macrophages, lowered anti-inflammatory macrophages, and diminished MSC recruitment in vitro and in vivo. In addition, new bone formation at the implantation site was significantly reduced in T cell-deficient mice compared to T cell-competent mice. Deficiency of CD4+ T cells exacerbated these effects compared to CD8+ T cell deficiency. Our results show the importance of CD4+ and CD8+ T cells in modulating the inflammatory response and promoting new bone formation in response to modified Ti implants. Statement of significanceCD4+ and CD8+ T cells are essential in modulating the peri-implant microenvironment during the inflammatory response to biomaterial implantation. This study shows that deficiency of either CD4+ or CD8+ T cell subsets altered macrophage polarization and reduced MSC recruitment and proliferation at the implantation site.

Abstract 3979: PD-1 signals regulate NKG7 that is required for CD8+ T cells to sustain cytotoxicity and durable antitumor memory responses

Abstract Cytotoxic CD8+ T cells play a key role in response to anti-PD-1/PD-L1 immune checkpoint inhibitors (ICI) therapy. However, the exact effector molecules that are regulated by PD-1 signals in cytotoxic CD8+ T cells have not been completely defined. Lack of this knowledge is a crucial problem in addressing how to overcome the low clinical response rate to ICI therapy. When exploring why certain patients not responding to ICI therapy, we found non-responders did not have an elevated NKG7 expression in CD8+ T cells as responders to ICI therapy. The difference in NKG7 expression in CD8+ T cells between non-responders and responders to anti-PD-1 therapy prompted us to investigate the potential role of PD-1 signaling in regulating NKG7 expression. To that end, we generated a CD8+ T cell-specific Pdcd1 conditional knockout mice (CD8 E8ICre-Pdcd1fl/fl, also known as CD8-PD-1 cKO) where Pdcd1 is deleted after thymic selection of single positive CD8+ T cells. We observed a delayed tumor growth and prolonged survival in CD8-PD-1 cKO mice compared to control mice after B16-OVA melanoma tumor challenge. On Day 12, when the CD8-PD-1 cKO mice demonstrated their ability to control tumor growth, we conducted single cell RNA sequencing on isolated tumor infiltrating CD8+ T cells, revealing a significant increase of Nkg7 expression in effector CD8+ T cells in the Pdcd1 deficient CD8+ T cells compared to the control wild type T cells. Pdcd1-deficient effector CD8+ T cells also had increased expression of genes linked to NFAT/Calcineurin signaling pathway including Nfatc1, S100a4, Tbet and Tox, suggesting Nkg7 could be regulated by Pdcd1 via the NFAT pathway. To determine the impact of increased NKG7 expression in CD8+ T cells, we used OVA protein as a surrogate tumor antigen in vaccination. We found a complete B16-OVA tumor rejection in CD8-PD-1 cKO mice compared to control mice when tumor cells were injected on day 7 after vaccination with OVA protein and poly (I:C) (as an adjuvant), but only a partial rejection on day 21. The CD8-PD-1 cKO mice that were tumor-free for 30-40 days rejected 2nd tumor challenge with B16-OVA tumors. This long-term protection is tumor antigen (OVA) specific because these mice did not reject B16F10 tumor cells that do not express OVA antigen. We also found effector memory CD8+ T cells with high cytotoxicity increased in the spleen of CD8-PD-1 cKO mice after OVA antigen immunization compared to control. In conclusion, we found NKG7 is one of the effector molecules in cytotoxic CD8+ T cells, which can be regulated by PD-1 signals through NFAT signaling. Targeting the PD-1-NFAT pathway may be a new option to overcome low responses of T cells to ICI therapy in treatment of refractory cancer. Citation Format: Zhiming Mao, Joanina Gicobi, Jacob Hirdler, Xin Liu, Michelle Hsu, Emilia Dellacecca, Wenjing Zhang, Fabrice Lucien-Matteoni, Hai dong. PD-1 signals regulate NKG7 that is required for CD8+ T cells to sustain cytotoxicity and durable antitumor memory responses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3979.

Psychological stress to ovalbumin peptide-specific T-cell receptor transgenic mice impairs the suppressive ability of type 1 regulatory T cell.

Numerous diseases of the immune system can be traced back to the malfunctioning of the regulatory T cells. The aetiology is unclear. Psychological stress can cause disruption to the immune regulation. The synergistic effects of psychological stress and immune response on immune regulation have yet to be fully understood. The intention of this study is to analyse the interaction between psychological stress and immune responses and how it affects the functional status of type 1 regulatory T (Tr1) cells. In this study, ovalbumin peptide T-cell receptor transgenic mice were utilised. Mice were subjected to restraint stress to induce psychological stress. An airway allergy murine model was established, in which a mouse strain with RING finger protein 20 (Rnf20)-deficient CD4+ T cells were used. The results showed that concomitant exposure to restraint stress and immune response could exacerbate endoplasmic reticulum stress in Tr1 cells. Corticosterone was responsible for the elevated expression of X-box protein-1 (XBP1) in mouse Tr1 cells after exposure to both restraint stress and immune response. XBP1 mediated the effects of corticosterone on inducing Rnf20 in Tr1 cells. The reduction of the interleukin-10 expression in Tr1 cells was facilitated by Rnf20. Inhibition of Rnf20 alleviated experimental airway allergy by restoring the immune regulatory ability of Tr1 cells. In conclusion, the functions of Tr1 cells are negatively impacted by simultaneous exposure to psychological stress and immune response. Tr1 cells' immune suppressive functions can be restored by inhibiting Rnf20, which has the translational potential for the treatment of diseases of the immune system.

Foxm1-Mediated Transcriptional Inactivation of NLRP3 Inflammasome Promotes Immunosuppression in Cervical Cancer.

Foxm1 functions as an oncogene in multiple human malignancies, including cervical cancer. However, the potential of Foxm1 in the tumor microenvironment (TME) is still unknown. The purpose of the present study is to investigate the role of Foxm1 in CD8+ T cell anti-tumor immunity. RT-qPCR is conducted to calculate mRNA levels. JASPAR is used to predict the binding sites between Foxm1 and NLRP3. ChIP assay is performed to verify the occupancy of Foxm1 on the promoter of NLRP3. Modulatory relationship between Foxm1 and NLRP3 is verified by luciferase assay. In vivo assays are conducted to further verify the role of Foxm1/NLRP3 axis in cervical cancer. HE staining assay is applied for histological analysis. Flow cytometry is conducted to determine the functions of immune cells. We found that Foxm1 knockdown decreases tumor burden and suppresses tumor growth of cervical cancer. Foxm1 knock-down promotes the infiltration of CD8+ T cells. Foxm1 deficiency inhibits the exhaustion of CD8+ T cells and facilitates the maintenance of CD8+ effector and stem-like T cells. Moreover, Foxm1 transcriptionally inactivates NLRP3 and suppresses the expression of innate cytokines IL-1β and IL-18. However, inhibition of NLRP3 inflammasome or neutralizing IL-1β and IL-18 inhibits anti-tumor immunity and promoted tumor growth in Foxm1 deficiency in CD8+ T cells. In summary, targeting Foxm1 mediates the activation of NLRP3 inflammasome and stimulates CD8+ T cell anti-tumor immunity in cervical cancer.

Immune infiltration, aggressive pathology, and poor survival outcomes in RECQL helicase deficient breast cancers

RECQL is essential for genomic stability. Here, we evaluated RECQL in 449 pure ductal carcinomas in situ (DCIS), 152 DCIS components of mixed DCIS/invasive breast cancer (IBC) tumors, 157 IBC components of mixed DCIS/IBC and 50 normal epithelial terminal ductal lobular units (TDLUs). In 726 IBCs, CD8+, FOXP3+, IL17+, PDL1+, PD1+ T-cell infiltration (TILs) were investigated in RECQL deficient and proficient cancers. Tumor mutation burden (TMB) was evaluated in five RECQL germ-line mutation carriers with IBC by genome sequencing. Compared with normal epithelial cells, a striking reduction in nuclear RECQL in DCIS was evident with aggressive pathology and poor survival. In RECQL deficient IBCs, CD8+, FOXP3+, IL17+ or PDL1+ TILs were linked with aggressive pathology and shorter survival. In germline RECQL mutation carriers, increased TMB was observed in 4/5 tumors. We conclude that RECQL loss is an early event in breast cancer and promote immune cell infiltration.