Alginate-based artificial antigen presenting cells expand functional CD8+ T cells with memory characteristics for adoptive cell therapy.

The development of artificial Antigen Presenting Cells (aAPCs) has led to improvements in adoptive T cell therapy (ACT), an immunotherapy, for cancer treatment. aAPCs help to streamline the consistent production and expansion of T cells, thus reducing the time and costs associated with ACT. However, several issues still exist with ACT, such as insufficient T cell potency, which diminishes the translational potential for ACT. While aAPCs have been used primarily to increase production efficiency of T cells for ACT, the intrinsic properties of a biomaterial-based aAPC may affect T cell phenotype and function. In CD8+ T cells, reactive oxygen species (ROS) and oxidative stress accumulation can activate Forkhead box protein O1 (FOXO1) to transcribe antioxidants which reduce ROS and improve memory formation. Alginate, a biocompatible and antioxidant rich biomaterial, is promising for incorporation into an aAPC formulation to modulate T cell phenotype. To investigate its utility, a novel alginate-based aAPC platform was developed that preferentially expanded CD8+ T cells with memory related features. Alginate-based aAPCs allowed for greater control of CD8+ T cell qualities, including, significantly improved in vivo persistence and augmented in vivo anti-tumor T cell responses.

Synergistic activity of Enterococcus Faecium-induced ferroptosis via expansion of IFN-γ+CD8+ T cell population in advanced hepatocellular carcinoma treated with sorafenib.

The gut microbiota plays an important role in the development and treatment of hepatocellular carcinoma (HCC). However, the implication of specific gut microbiota in targeted sorafenib therapy for advanced HCC and the microbiota mode of action, remain to be elucidated. Here, we confirmed that four bacterial genera, Lachnoclostridium, Lachnospira, Enterobacter and Enterococcus, are associated with the therapeutic efficacy of Sorafenib, and that Enterobacter faecium (Efm) plays a crucial role in modulating the sorafenib activity. The effective colonization by Emf induced the IL-12 and IFN-γ production and an increased proportion of IFN-γ+CD8+ T cells in the tumor microenvironment. Finally, exopolysaccharides (EPS) from Efm were the primary inducer to prompt IFN-γ+CD8+ T cells to secrete IFN-γ, which together with sorafenib instigated ferroptosis in HCC cells. Collectively, these results indicate that Efm is a promising probiotics that enhances the efficacy of sorafenib treatment in advanced HCC.

CD8+T cell infiltration-associated barrier function of brain endothelial cells is enhanced by Astragalus polysaccharides via inhibiting PI3K/AKT signaling pathway.

Pathogenic CD8+T cells play an essential role in neuroinflammation and neural injury, which leads to the progression of inflammatory neurological disorders. Thus, blocking the infiltration of CD8+T cells is necessary for the treatment of neuroinflammatory diseases. Our previous study demonstrated that Astragalus polysaccharides (APS) could significantly reduce the infiltration of CD8+T cells in experimental autoimmune encephalomyelitis (EAE) mice. However, the mechanism by which APS suppress CD8+T cell infiltration remains elusive. In this study, we further found that APS could reduce the CD8+T cell infiltration in EAE and lipopolysaccharide (LPS)-induced neuroinflammatory model. Furthermore, we established the mouse brain endothelial cell (bEnd.3) inflammatory injury model by interleukin-1ß (IL-1ß) or LPS in vitro. The results showed that APS treatment downregulated the expression of vascular cell adhesion molecule1 (VCAM1) to decrease the adhesion of CD8+T cells to bEnd.3 cells. APS also upregulated the expression of zonula occluden-1 (ZO-1) and vascular endothelial cadherin (VE-cadherin) to reduce the trans-endothelial migration of CD8+T cells. The PI3K/AKT signaling pathway might mediate this protective effect of APS on bEnd.3 cells against inflammatory injury. In addition, we demonstrated the protective effect of APS on the integrity of brain endothelial cells in an LPS-induced neuroinflammatory model. In summary, our results indicate that APS can reduce peripheral CD8+T cell infiltration via enhancing the barrier function of brain endothelial cells, it may be a potential for the prevention of neuroinflammatory diseases.

Immunological hide-and-seek: epigenetically reprogrammed cancer cells and the dynamics of CD8+ T cells.

Cancer remains a global health burden, shaped by both genetic mutations and epigenetic dysregulation. Epigenetic alteration plays a pivotal role in tumorigenesis, immune response modulation, and the emergence of treatment resistance. This review emphasizes the intricate interplay between epigenetically reprogrammed cancer cells and the tumor microenvironment (TME), a relationship central to the immunoediting concept, which encompasses elimination, equilibrium, and escape phases. This review highlights the significance of CD8+ T cells as potent anticancer agents and discusses the mechanisms by which tumor cells evade immune surveillance and evolve resistance to immunotherapy. Such evasion entails the regulation of inhibitory molecules, antigen presentation machinery, and cytokine milieu. Furthermore, this review explores the complex dynamics culminating in CD8+ T cell dysfunction within the TME. In summary, this work offers insights into the indispensable role of epigenetic mechanisms in bolstering cancer cell survival amidst immunological challenges within the TME.

Unveiling the role of taurine and SLC6A6 in tumor immune evasion: Implications for gastric cancer therapy.

Metabolic changes are key drivers of tumor progression. Understanding how metabolic reprogramming promotes tumor development and identifying key metabolic activities are essential for improving tumor diagnosis and treatment. Among the numerous transporters in the body, solute carriers (SLCs) are particularly significant, often overexpressed in cancer cells to meet the tumor's demand for nutrients and energy. While the role of SLCs in nutrient absorption within the gastrointestinal tract is well-established, their specific role in gastric cancer (GC) remains unclear. Recently, Xiaodi Zhao's team investigated the critical role of taurine and its transporter, SLC6A6, in anti-tumor immunity and clinical outcomes. Notably, this research marks the first instance of taurine exhibiting a dual role. It promotes tumor growth in immunodeficient mice while inhibiting it in immunocompetent mice. The study found that taurine exerts its anti-cancer effects by modulating CD8+ T cells rather than directly inhibiting tumor cells, revealing the SP1-SLC6A6 axis as a key mechanism behind chemotherapy-induced immune evasion. Our work further explored the potential, advantages, and challenges of using taurine and SLC6A6 as biomarkers and therapeutic targets in gastric cancer. We aim to underscore their importance in both basic research and clinical applications, providing valuable insights and guidance for future investigations.

SIN3B Loss Heats up Cold Tumor Microenvironment to Boost Immunotherapy in Pancreatic Cancer.

Despite progress significant advances in immunotherapy for some solid tumors, pancreatic ductal adenocarcinoma (PDAC) remains unresponsive poorly responsive to such interventions, largely due to its highly immunosuppressive tumor microenvironment (TME) with limited CD8+ T cell infiltration. This study explores the role of the epigenetic factor Sin3B in the PDAC TME. Using murine PDAC models, we found that tumor cell-intrinsic Sin3B loss reshapes the TME, increasing CD8+ T cell infiltration and cytotoxicity, thus impeding tumor progression and enhancing sensitivity to anti-PD1 treatment. Sin3B-deficient tumor cells exhibited amplified CXCL9/10 secretion in response to Interferon-gamma (IFNγ), creating a positive feedback loop via the CXCL9/10-CXCR3 axis, thereby intensifying the anti-tumor immune response against PDAC. Mechanistically, extensive epigenetic regulation is uncovered by Sin3B loss, particularly enhanced H3K27Ac distribution on genes related to immune responses in PDAC cells. Consistent with the murine model findings, analysis of human PDAC samples revealed a significant inverse correlation between SIN3B levels and both CD8+ T cell infiltration and CXCL9/10 expression. Notebly, PDAC patients with lower SIN3B expression showed a more favorable response to anti-PD1 therapy. The findings suggest that targeting SIN3B can enhance cytotoxic T cell infiltration into the tumor site and improve immunotherapy efficacy in PDAC, offering potential avenues for therapeutic biomarker or target in this challenging disease.

UFMylation is involved in serum inflammatory cytokines generation and splenic T cell activation induced by lipopolysaccharide.

UFMylation, a novel ubiquitin-like protein modification system, has been recently found to be activated in inflammation. However, the effects of UFMylation activation on inflammation in vivo remains unclear. In the present study, we generated a UFMylation activated mice using transgenic (TG) techniques. Lipopolysaccharide (LPS) was used to induce systemic inflammation in both TG and non-transgenic (NTG) mice. Serum cytokines were detected using a Mouse Cytokine Array, and the proportions of splenic NK, B and T cells were determined by using flow cytometry. We found that TG mice showed increased serum G-CSF, TNF RII and decreased serum TCA-3, CD30L, bFGF, IL-15 and MIG compared with NTG mice at baseline. Furthermore, serum cytokines in TG mice exhibited different responses to LPS compared to NTG mice. LPS up-regulated serum TNF RII, G-CSF, MCP-5, RANTES, KC, BLC, MIG and down-regulated IL-1b, IL-2, IL-3, IL-4, IL-5, IL-7, IL-10, IL-12p40, IL-15, IL-17, IFN-γ, TCA-3, Eotaxin-2, LIX, MCP-1, TNFα, GM-CSF in NTG mice, whereas LPS up-regulated G-CSF, MCP-5, RANTES, KC, BLC, MIG, ICAM-1, PF4, Eotaxin, CD30L, MIP-1a, TNFRI and down-regulated IL-1b, IL-3, LIX, MCP-1, TNFα, GM-CSF in TG mice. Data from flow cytometry indicated that LPS significantly reduced the percentages of NK and NKT cells in NTG mice, whereas UFMylation activation inhibited LPS-induced NKT cell decrease. The proportions of B cells, total CD4+ and total CD8+ T cells were comparable between TG and NTG mice in response to LPS treatment, whereas the percentages of CD4+CD69+ and CD8+CD69+T cells were lower in TG mice. These findings suggest that UFMylation may alter LPS-induced serum cytokine profile and participate in splenic T cell activation in vivo.

Local TSH/TSHR signaling promotes CD8+ T cell exhaustion and immune evasion in colorectal carcinoma.

BACKGROUND: Dysfunction of CD8+ T cells in the tumor microenvironment (TME) contributes to tumor immune escape and immunotherapy tolerance. The effects of hormones such as leptin, steroid hormones, and glucocorticoids on T cell function have been reported previously. However, the mechanism underlying thyroid-stimulating hormone (TSH)/thyroid-stimulating hormone receptor (TSHR) signaling in CD8+ T cell exhaustion and tumor immune evasion remain poorly understood. This study was aimed at investigating the effects of TSH/TSHR signaling on the function of CD8+ T cells and immune evasion in colorectal cancer (CRC). METHODS: TSHR expression levels in CD8+ T cells were assessed with immunofluorescence and flow cytometry. Functional investigations involved manipulation of TSHR expression in cellular and mouse models to study its role in CD8+ T cells. Mechanistic insights were mainly gained through RNA-sequencing, Western blotting, chromatin immunoprecipitation and luciferase activity assay. Immunofluorescence, flow cytometry and Western blotting were used to investigate the source of TSH and TSHR in CRC tissues. RESULTS: TSHR was highly expressed in cancer cells and CD8+ T cells in CRC tissues. TSH/TSHR signaling was identified as the intrinsic pathway promoting CD8+ T cell exhaustion. Conditional deletion of TSHR in CD8+ tumor-infiltrating lymphocytes (TILs) improved effector differentiation and suppressed the expression of immune checkpoint receptors such as programmed cell death 1 (PD-1) and hepatitis A virus cellular receptor 2 (HAVCR2 or TIM3) through the protein kinase A (PKA)/cAMP-response element binding protein (CREB) signaling pathway. CRC cells secreted TSHR via exosomes to increase the TSHR level in CD8+ T cells, resulting in immunosuppression in the TME. Myeloid-derived suppressor cells (MDSCs) was the main source of TSH within the TME. Low expression of TSHR in CRC was a predictor of immunotherapy response. CONCLUSIONS: The present findings highlighted the role of endogenous TSH/TSHR signaling in CD8+ T cell exhaustion and immune evasion in CRC. TSHR may be suitable as a predictive and therapeutic biomarker in CRC immunotherapy.

Immune escape between endoplasmic reticulum stress-related cancer cells and exhausted CD8+T cells leads to neoadjuvant chemotherapy resistance in ovarian cancer.

Our study aims to explore the effects of neoadjuvant chemotherapy (NACT) on tumour cells and immune cells in the immune microenvironment of patients with high-grade serous ovarian cancer (HGSOC). Single-cell RNA sequencing data of paired ovarian cancer tissues were analysed before and after NACT in 11 patients with HGSOC. The effect of NACT on two major cell components of the tumour microenvironment, epithelial cells and CD8+T cells, was investigated. The mechanisms of epithelial cell evasion by NACT and immune killing were explored from the perspectives of gene expression, functional characteristics, transcriptional regulation, and cell communication. Key targets for reversing NACT resistance were identified and possible therapeutic strategies proposed. While NACT improved the de novo differentiation of anti-tumour CD8+T cells, enhancing their anti-tumour function, it increased the proportion of cancer cells with high HSP90B1 expression. Thus, the potential reasons for NACT resistance were identified as: 1) high levels of endoplasmic reticulum stress (ERS) characteristics, 2) high expression of the MDK-NCL ligand-receptor pair between them and exhausted CD8+T cells before NACT, and 3) high expression of the NECTIN2-TIGIT immune ligand-receptor pair between them and exhausted CD8+T cells after NACT. Thus, our study reveals the mechanisms underlying NACT resistance in patients with HGSOC from the perspective of the independent and interactive roles of cancer cells and CD8+T cells. We propose therapeutic strategies targeting the ERS marker HSP90B1 and the immune escape marker MDK before or during NACT, while targeting NECTIN2 blockade after NACT. This approach may offer new insights into combination treatments for patients with HGSOC displaying NACT resistance.

Systemic T-cell activation and interferon-γ activity in indeterminate severe hepatitis (iSH) are reminiscent of hemophagocytic lymphohistiocytosis (HLH): Implications for T-cell and interferon-γ directed therapies.

BACKGROUND: Severe hepatitis cases in children are increasingly recognized, however, the exact etiology remains unknown in a significant proportion of patients. Cases of indeterminate severe hepatitis (iSH) may progress to indeterminate pediatric acute liver failure (iPALF), hence understanding the immunobiology is critical to preventing disease progression. Hemophagocytic lymphohistiocytosis (HLH) is a systemic hyperinflammatory disorder associated with T-cell and macrophage activation with liver injury. OBJECTIVES: We hypothesized a high proportion of patients with iSH demonstrate systemic T-cell activation similar to HLH prior to developing iPALF and that the degree of T-cell activation in iSH might correlate with outcomes. METHODS: From 2019-2022, 14 patients with iSH and 7 patients with PALF of known, non-immune etiology were prospectively enrolled. We compared immune signatures of iSH, HLH, known PALF, and healthy controls. RESULTS: We found that patients with iSH have increased CD8+ T-cell activation and high interferon-γ activity similar to HLH. The amplitude of CD8+ T-cell activation was predictive of iSH progression to iPALF. We also found that in patients with iSH, ferritin had only modest elevation. However, age-normalized plasma soluble interleukin-2 receptor (sIL-2R) to ferritin level ratio can distinguish iSH from known PALF and HLH. As a proof of concept, we report that in three patients with steroid refractory iSH, emapalumab, an IFN-γ blocking antibody used in combination with steroids, improved liver function and may have prevented progression to PALF. CONCLUSIONS: Our data suggests flow-based T-cell activation markers could help in early identification and risk stratification for targeted intervention in patients with iSH.

A CD8+ T cell related immune score predicts survival and refines the risk assessment in acute myeloid leukemia.

Although advancements in genomic and epigenetic research have deepened our understanding of acute myeloid leukemia (AML), only one-third of patients can achieve durable remission. Growing evidence suggests that the immune microenvironment in bone marrow influences prognosis and survival in AML. There is a specific association between CD8+ T cells and the prognosis of AML patients. To develop a CD8+ T cell-related immune risk score for AML, we first evaluated the accuracy of CIBERSORTx in predicting the abundance of CD8+ T cells in bulk RNA-seq and found it significantly correlated with observed single-cell RNA sequencing data and the proportions of CD8+ T cells derived from flow cytometry. Next, we constructed the CTCG15, a 15-gene prognostic signature, using univariate and LASSO regression on the differentially expressed genes between CD8+ THigh and CD8+ TLow groups. The CTCG15 was further validated across six datasets in different platforms. The CTCG15 has been shown to be independent of established prognostic markers, and can distill transcriptomic consequences of several genetic abnormalities closely related to prognosis in AML patients. Finally, integrating this model into the 2022 European LeukemiaNet contributed to a higher predictive power for prognosis prediction. Collectively, our study demonstrates that CD8+ T cell-related signature could improve the comprehensive risk stratification and prognosis prediction in AML.

SGLT2 inhibitor promotes ketogenesis to improve MASH by suppressing CD8+ T cell activation.

During the progression of metabolic dysfunction-associated steatohepatitis (MASH), the accumulation of auto-aggressive CD8+ T cells significantly contributes to liver injury and inflammation. Empagliflozin (EMPA), a highly selective inhibitor of sodium-glucose co-transporter 2 (SGLT2), exhibits potential therapeutic benefits for liver steatosis; however, the underlying mechanism remains incompletely elucidated. Here, we found that EMPA significantly reduced the hepatic accumulation of auto-aggressive CD8+ T cells and lowered granzyme B levels in mice with MASH. Mechanistically, EMPA increased ß-hydroxybutyric acid by promoting the ketogenesis of CD8+ T cells via elevating 3-hydroxybutyrate dehydrogenase 1 (Bdh1) expression. The ß-hydroxybutyric acid subsequently inhibited interferon regulatory factor 4 (Irf4), which is crucial for CD8+ T cell activation. Furthermore, the ablation of Bdh1 in T cells aggravated the manifestation of MASH and hindered the therapeutic efficacy of EMPA. Moreover, a case-control study also showed that SGLT2 inhibitor treatment repressed CD8+ T cell infiltration and improved liver injury in patients with MASH. In summary, our study indicates that SGLT2 inhibitors can target CD8+ T cells and may be an effective strategy for treating MASH.

JAK/STAT Signaling Pathway Mediates Anti-Tumor Immunity of CD8+ T Cells in Renal Cancer.

Background: CD8+ T cells play a crucial role in immune responses, and have significant potential in tumor immunotherapy. The JAK/STAT pathway is essential for cytokine signal transduction and is linked to immune escape. However, its role in mediating CD8+ T cell anti-tumor immunity in renal cancer is not fully understood. Objective: To study the mechanisms underlying CD8+ T cell-mediated anti-tumor immunity and propose new possibilities for immunotherapy in patients with renal cancer. Methods: CD8+ T cells from mouse spleens were sorted using immunomagnetic beads, and their purity was confirmed by flow cytometry. Proliferation was analyzed using CCK-8 and CFSE assays. Activation of CD8+ T cells was assessed through ELISA and Western blotting. The malignant properties of Renca cells were evaluated through flow cytometry, Calcein-AM/PI staining, wound healing, Transwell, Western blot, and immunofluorescence. A subcutaneous tumor model in nude mice was used to examine the role of JAK1/STAT1 pathway in vivo. Results: Inhibitors of JAK1 and STAT1 significantly reduced the proliferation and activation of CD8+ T cell. Co-culture with CD8+ T cells increased apoptosis and inhibited the proliferation, migration, and invasion of Renca cells. The effects were diminished by JAK1 and STAT1 inhibitors, confirming that CD8+ T cells exert antitumor effects through the JAK1/STAT1 pathway. In vivo, inhibition of this pathway reduced the anti-tumor effects of CD8+ T cells. Conclusion: Inhibitors of JAK1 and STAT1 weakened the antitumor effects of CD8+ T cells, suggesting that targeting this pathway could enhance CD8+ T cell-mediated immunity in renal cancer.

Elimination of Human Papillomavirus 16-Positive Tumors by a Mucosal rAd5 Therapeutic Vaccination in a Pre-Clinical Murine Study.

Therapeutic vaccination can harness the body's cellular immune system to target and destroy cancerous cells. Several treatment options are available to eliminate pre-cancerous and cancerous lesions caused by human papillomaviruses (HPV), but may not result in a long-term cure. Therapeutic vaccination may offer an effective, durable, and minimally intrusive alternative. We developed mucosally delivered, recombinant, non-replicating human adenovirus type 5 (rAd5)-vectored vaccines that encode HPV16's oncogenic proteins E6 and E7 alongside a molecular dsRNA adjuvant. The induction of antigen-specific T cells and the therapeutic efficacy of rAd5 were evaluated in a mouse model of HPV tumorigenesis where E6E7-transformed cells, TC-1, were implanted subcutaneously in C57BL/6 mice. After tumor growth, mice were treated intranasally with rAd5 vaccines expressing the wildtype form of E6E7 (rAd5-16/E6E7Wt) in combination with an anti-PD-1 antibody or isotype control. Animals treated with rAd5-16/E6E7Wt with and without anti-PD-1 had significant reductions in tumor volume and increased survival compared to controls. Further, animals treated with rAd5-16/E6E7Wt had increased CD4+ and CD8+ tumor-infiltrating lymphocytes (TILs) and produced a cytotoxic tumor microenvironment. In a second study, the immunogenicity of a non-transformative form of E6E7 (rAd5-16/E6E7Mu) and a vaccine encoding predicted T cell epitopes of E6E7 (rAd5-16/E6E7epi) were evaluated. These vaccines elicited significant reductions in TC-1 tumor volume and increased survival of animals. Antigen-specific CD8+ T effector memory cells were observed in the animals treated with E6E7-encoding rAd5, but not in the rAd5-empty group. The work described here demonstrates that this mucosal vaccination can be used therapeutically to elicit specific cellular immunity and further identifies a clinical candidate with great potential for the treatment and prevention of human cervical cancer.

GSK-3ß in Dendritic Cells Exerts Opposite Functions in Regulating Cross-Priming and Memory CD8 T Cell Responses Independent of ß-Catenin.

GSK-3ß plays a critical role in regulating the Wnt/ß-catenin signaling pathway, and manipulating GSK-3ß in dendritic cells (DCs) has been shown to improve the antitumor efficacy of DC vaccines. Since the inhibition of GSK-3ß leads to the activation of ß-catenin, we hypothesize that blocking GSK-3ß in DCs negatively regulates DC-mediated CD8 T cell immunity and antitumor immunity. Using CD11c-GSK-3ß-/- conditional knockout mice in which GSK-3ß is genetically deleted in CD11c-expressing DCs, we surprisingly found that the deletion of GSK-3ß in DCs resulted in increased antitumor immunity, which contradicted our initial expectation of reduced antitumor immunity due to the presumed upregulation of ß-catenin in DCs. Indeed, we found by both Western blot and flow cytometry that the deletion of GSK-3ß in DCs did not lead to augmented expression of ß-catenin protein, suggesting that GSK-3ß exerts its function independent of ß-catenin. Supporting this notion, our single-cell RNA sequencing (scRNA-seq) analysis revealed that GSK-3ß-deficient DCs exhibited distinct gene expression patterns with minimally overlapping differentially expressed genes (DEGs) compared to DCs with activated ß-catenin. This suggests that the deletion of GSK-3ß in DCs is unlikely to lead to upregulation of ß-catenin at the transcriptional level. Consistent with enhanced antitumor immunity, we also found that CD11c-GSK-3ß-/- mice exhibited significantly augmented cross-priming of antigen-specific CD8 T cells following DC-targeted vaccines. We further found that the deletion of GSK-3ß in DCs completely abrogated memory CD8 T cell responses, suggesting that GSK-3ß in DCs also plays a negative role in regulating the differentiation and/or maintenance of memory CD8 T cells. scRNA-seq analysis further revealed that although the deletion of GSK-3ß in DCs positively regulated transcriptional programs for effector differentiation and function of primed antigen-specific CD8 T cells in CD11c-GSK-3ß-/- mice during the priming phase, it resulted in significantly reduced antigen-specific memory CD8 T cells, consistent with diminished memory responses. Taken together, our data demonstrate that GSK-3ß in DCs has opposite functions in regulating cross-priming and memory CD8 T cell responses, and GSK-3ß exerts its functions independent of its regulation of ß-catenin. These novel insights suggest that targeting GSK-3ß in cancer immunotherapies must consider its dual role in CD8 T cell responses.

Focusing on CD8+ T-cell phenotypes: improving solid tumor therapy.

Vigorous CD8+ T cells play a crucial role in recognizing tumor cells and combating solid tumors. How T cells efficiently recognize and target tumor antigens, and how they maintain the activity in the "rejection" of solid tumor microenvironment, are major concerns. Recent advances in understanding of the immunological trajectory and lifespan of CD8+ T cells have provided guidance for the design of more optimal anti-tumor immunotherapy regimens. Here, we review the newly discovered methods to enhance the function of CD8+ T cells against solid tumors, focusing on optimizing T cell receptor (TCR) expression, improving antigen recognition by engineered T cells, enhancing signal transduction of the TCR-CD3 complex, inducing the homing of polyclonal functional T cells to tumors, reversing T cell exhaustion under chronic antigen stimulation, and reprogramming the energy and metabolic pathways of T cells. We also discuss how to participate in the epigenetic changes of CD8+ T cells to regulate two key indicators of anti-tumor responses, namely effectiveness and persistence.

Impaired mitochondrial oxidative phosphorylation induces CD8+ T cell exhaustion.

CD8+ T cells play a crucial role in anti-tumor immunity, but their function can be impaired by exhaustion induced by prolonged antigen stimulation. Mitochondrial dysfunction, a hallmark of the tumor microenvironment (TME), has been linked to various pathologies, but its specific role in CD8+ T cell exhaustion remains underexplored. Here, we established an in vitro model of CD8+ T cell exhaustion by co-culturing OVA-specific OT1 CD8+ T cells with OVA-expressing MC38 tumor cells. Next, we investigated the impact of mitochondrial dysfunction on exhaustion using pharmacological inhibitors targeting the electron transport chain. The role of the mitochondrial complex I component NDUFA10 was further examined through genetic knockout in CD8+ T cells using CRISPR-Cas9. Inhibition of the mitochondrial electron transport chain significantly accelerated CD8+ T cell exhaustion in vitro. Knockout of NDUFA10 in CD8+ T cells led to enhanced tumor growth and increased exhaustion of tumor-infiltrating CD8+ T cells in a Rag1-/- tumor-bearing transfer model. This study highlights the critical role of mitochondrial function in regulating CD8+ T cell exhaustion and anti-tumor activity, providing new insights into the metabolic underpinnings of immune dysfunction in cancer.

Clinical and Histologic Variants of CD8+ Cutaneous T-Cell Lymphomas.

Although the vast majority of CTCL subtypes are of the CD4+ T-helper cell differentiation phenotype, there is a spectrum of CD8+ variants that manifest wide-ranging clinical, histologic, and phenotypic features that inform the classification of the disease. CD8, like CD4, and cytotoxic molecules (including TIA and granzyme) are readily detectable via IHC staining of tissue and, when expressed on the phenotypically abnormal T-cell population, can help distinguish specific CTCL subtypes. Nonetheless, given that the histopathologic differential for CD8+ lymphoproliferative disorders and lymphomas may range from very indolent lymphomatoid papulosis (LyP) to aggressive entities like CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma (AECTCL), CD8 and/or cytotoxic molecule expression alone is insufficient for diagnosis and is not in itself an indicator of prognosis. We present a review of CTCL subtypes that can demonstrate CD8 positivity: CD8+ mycosis fungoides (MF), LyP type D, subcutaneous panniculitis-like T-cell lymphoma (SPTCL), primary cutaneous gamma/delta T-cell lymphoma (PCGDTL), CD8+ AECTCL, and acral CD8+ T-cell lymphoproliferative disorder (acral CD8+ TCLPD). These diseases may have different clinical manifestations and distinctive treatment algorithms. Due to the rare nature of these diseases, it is imperative to integrate clinical, histologic, and immunohistochemical findings to determine an accurate diagnosis and an appropriate treatment plan.

Circ_0001947 encapsulated by small extracellular vesicles promotes gastric cancer progression and anti-PD-1 resistance by modulating CD8+ T cell exhaustion.

BACKGROUND: While small extracellular vesicles (sEVs)-derived circular RNAs (circRNAs) have been emerged as significant players in cancer, the function and underlying mechanism of sEVs-derived circRNAs in anti-cancer immunity remain unclear. METHODS: Gastric cancer (GC)-derived circRNAs were identified using RNA-seq data from GEO datasets and quantitative reverse transcription polymerase chain reaction (qRT-PCR), RNA immunoprecipitation, dual-luciferase assay, and bioinformatics analysis were performed to investigate the regulatory axis. Transwell assay, wound healing assay, cell counting kit-8 (CCK-8) assay, and xenograft models were used to evaluate its role in GC progression in vivo and in vitro. The delivery of specific circRNAs into sEVs were verified through electron microscopy, nanoparticle tracking analysis (NTA) and fuorescence in situ hybridization (FISH). Flow cytometric analysis and immunohistochemical staining were conducted to find out how specific circRNAs mediated CD8+ T cell exhaustion and resistant to anti-programmed cell death 1 (PD-1) therapy. RESULTS: We identified that circ_0001947, packaged by GC-derived sEVs, was obviously elevated in GC and was associated with poor clinical outcome. High circ0001947 level augmented the proliferation, migration, and invasion of GC cells. Mechanistically, circ0001947 sponged miR-661 and miR-671-5p to promote the expression of CD39, which further facilitated CD8+ T cell exhaustion and immune resistance. Conversely, blocking circ_0001947 attenuated CD8+ T cell exhaustion and increased the response to anti-PD-1 therapy. CONCLUSIONS: Our study manifested the therapeutic potential of targeting sEVs-transmitted circ_0001947 to prohibit CD8+ T cell exhaustion and immune resistance in GC.

Acidity suppresses CD8 + T-cell function by perturbing IL-2, mTORC1, and c-Myc signaling.

CD8 + T cells have critical roles in tumor control, but a range of factors in their microenvironment such as low pH can suppress their function. Here, we demonstrate that acidity restricts T-cell expansion mainly through impairing IL-2 responsiveness, lowers cytokine secretion upon re-activation, and reduces the cytolytic capacity of CD8 + T cells expressing low-affinity TCR. We further find decreased mTORC1 signaling activity and c-Myc levels at low pH. Mechanistically, nuclear/cytoplasmic acidification is linked to mTORC1 suppression in a Rheb-, Akt/TSC2/PRAS40-, GATOR1- and Lkb1/AMPK-independent manner, while c-Myc levels drop due to both decreased transcription and higher levels of proteasome-mediated degradation. In addition, lower intracellular levels of glutamine, glutamate, and aspartate, as well as elevated proline levels are observed with no apparent impact on mTORC1 signaling or c-Myc levels. Overall, we suggest that, due to the broad impact of acidity on CD8 + T cells, multiple interventions will be required to restore T-cell function unless intracellular pH is effectively controlled.