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Plasma cell-CD8+ T cell co-enrichment distinguishes immunotherapy-responsive hepatocellular carcinoma subtypes.

BACKGROUND: Hepatocellular carcinoma (HCC) is characterised by significant racial disparities in incidence and outcomes, yet whether these reflect distinct tumour biology or differential distribution of molecular subtypes among immunotherapy patients remains unclear. METHODS: We characterised molecular heterogeneity among 46 patients with HCC of differing background population from the NCI-CLARITY cohort receiving immune checkpoint inhibitor therapy, using transcriptomic and genomic profiling, with validation across multiple independent cohorts. RESULTS: Differential expression analysis comparing African American versus non-African American patients identified 126 genes, of which 55 demonstrated tumour-specific expression across independent validation cohorts with paired tumour-normal samples. Consensus clustering revealed two molecular subtypes with no significant race association, indicating these clusters capture tumour-intrinsic biology rather than ancestry. The genomic landscape showed minimal differences between subtypes. A prognostic signature derived from these expression profiles demonstrated significant risk stratification in the NCI-CLARITY cohort and TCGA-LIHC, but not in Asian cohorts, suggesting population-specific applicability. Immune deconvolution revealed that the two subtypes represent distinct immune microenvironments: one subtype exhibited markedly elevated plasma cell infiltration with strong plasma cell-CD8+T cell correlation suggesting coordinated adaptive immunity, along with elevated tertiary lymphoid structure signatures. The other subtype showed regulatory T cell-macrophage correlation and enrichment for immune-excluded phenotypes. The immune-enriched subtype trended towards higher immunotherapy response rates. CONCLUSIONS: Molecular heterogeneity in HCC reveals distinct tumour-immune ecosystems that transcend racial classification. Tumour immune heterogeneity in HCC reflects distinct molecular patterns, with immune hot tumours characterised by elevated tertiary lymphoid structure signatures and enriched plasma cell and CD8+T cells. These patterns may serve as prognostic biomarkers for immunotherapy patient stratification and demonstrate the value of diverse cohort representation in identifying clinically relevant therapeutic targets.

Gastrointestinal Cancer

High baseline PD-1+ CD8 T Cells and TIGIT+ CD8 T Cells in circulation associated with response to PD-1 blockade in patients with non-small cell lung cancer.

Blockade of PD-1 or its ligand PD-L1 with antibodies revolutionized treatment for stage III and IV non-small cell lung cancer (NSCLC) since FDA approval in 2015. However, resistance to PD-1/PD-L1 blockade remains a challenge, highlighting the need for biomarkers. This study analyzed 36 stage III and IV NSCLC patients, classified as responders or non-responders by iRECIST criteria. Peripheral blood mononuclear cells collected at baseline and post-treatment were examined for surface and intracellular markers via flow cytometry. CITE sequencing of CD8 T cells from three patients and plasma ctDNA analysis from 13 patients was performed using an ultrasensitive barcoding and next-generation sequencing method. Phenotypic analysis of CD8 T cells revealed higher TIGIT and PD-1 expression at baseline in responders compared to non-responders. Long-term responders (> 21 months) exhibited increased TCF-1+PD-1+ CD8 T cell frequencies relative to shorter-term responders (> 15 months) and non-responders. CITE sequencing revealed intrinsic differences in immune regulation pathways between responders and non-responders. Finally, non-responders showed elevated and increasing ctDNA levels post-treatment, correlating with declining TCF-1+PD-1+ CD8 T cells. Our data suggests combining CD8 T cell analysis with ctDNA dynamics could identify promising biomarkers for monitoring clinical response and treatment efficacy to PD-1/PD-L1 blockade in NSCLC.

Humans

Intratumor childhood vaccine-specific CD4+ T-cell recall coordinates antitumor CD8+ T cells and eosinophils.

BACKGROUND: Antitumor mechanisms of CD4+ T cells remain crudely defined, and means to effectively harness CD4+ T-cell help for cancer immunotherapy are lacking. Pre-existing memory CD4+ T cells hold potential to be leveraged for this purpose. Moreover, the role of pre-existing immunity in virotherapy, particularly recombinant poliovirus immunotherapy where childhood polio vaccine specific immunity is ubiquitous, remains unclear. Here we tested the hypothesis that childhood vaccine-specific memory T cells mediate antitumor immunotherapy and contribute to the antitumor efficacy of polio virotherapy. METHODS: The impact of polio immunization on polio virotherapy, and the antitumor effects of polio and tetanus recall were tested in syngeneic murine melanoma and breast cancer models. CD8+ T-cell and B-cell knockout, CD4+ T-cell depletion, CD4+ T-cell adoptive transfer, CD40L blockade, assessments of antitumor T-cell immunity, and eosinophil depletion defined antitumor mechanisms of recall antigens. Pan-cancer transcriptome data sets and polio virotherapy clinical trial correlates were used to assess the relevance of these findings in humans. RESULTS: Prior vaccination against poliovirus substantially bolstered the antitumor efficacy of polio virotherapy in mice, and intratumor recall of poliovirus or tetanus immunity delayed tumor growth. Intratumor recall antigens augmented antitumor T-cell function, caused marked tumor infiltration of type 2 innate lymphoid cells and eosinophils, and decreased proportions of regulatory T cells (Tregs). Antitumor effects of recall antigens were mediated by CD4+ T cells, limited by B cells, independent of CD40L, and dependent on eosinophils and CD8+ T cells. An inverse relationship between eosinophil and Treg signatures was observed across The Cancer Genome Atlas (TCGA) cancer types, and eosinophil depletion prevented Treg reductions after polio recall. Pretreatment polio neutralizing antibody titers were higher in patients living longer, and eosinophil levels increased in the majority of patients, after polio virotherapy. CONCLUSION: Pre-existing anti-polio immunity contributes to the antitumor efficacy of polio virotherapy. This work defines cancer immunotherapy potential of childhood vaccines, reveals their utility to engage CD4+ T-cell help for antitumor CD8+ T cells, and implicates eosinophils as antitumor effectors of CD4+ T cells.

Mice

Mucosal memory CD8⁺ T cells are selected in the periphery by an MHC class I molecule.

The presence of immune memory at pathogen-entry sites is a prerequisite for protection. Nevertheless, the mechanisms that warrant immunity at peripheral interfaces are not understood. Here we show that the nonclassical major histocompatibility complex (MHC) class I molecule thymus leukemia antigen (TL), induced on dendritic cells interacting with CD8αα on activated CD8αβ(+) T cells, mediated affinity-based selection of memory precursor cells. Furthermore, constitutive expression of TL on epithelial cells led to continued selection of mature CD8αβ(+) memory T cells. The memory process driven by TL and CD8αα was essential for the generation of CD8αβ(+) memory T cells in the intestine and the accumulation of highly antigen-sensitive CD8αβ(+) memory T cells that form the first line of defense at the largest entry port for pathogens.

Animals

The transcription factor NFAT promotes exhaustion of activated CD8⁺ T cells.

During persistent antigen stimulation, CD8(+) T cells show a gradual decrease in effector function, referred to as exhaustion, which impairs responses in the setting of tumors and infections. Here we demonstrate that the transcription factor NFAT controls the program of T cell exhaustion. When expressed in cells, an engineered form of NFAT1 unable to interact with AP-1 transcription factors diminished T cell receptor (TCR) signaling, increased the expression of inhibitory cell surface receptors, and interfered with the ability of CD8(+) T cells to protect against Listeria infection and attenuate tumor growth in vivo. We defined the genomic regions occupied by endogenous and engineered NFAT1 in primary CD8(+) T cells and showed that genes directly induced by the engineered NFAT1 overlapped with genes expressed in exhausted CD8(+) T cells in vivo. Our data show that NFAT promotes T cell anergy and exhaustion by binding at sites that do not require cooperation with AP-1.

Animals

Mapping self-associating chromatin hubs identifies Id proteins as key determinants of exhausted CD8+ T cell fate.

Within days of exposure to chronic viral infections, activated CD8+ T cells differentiate into Tcf1-Slamf6loTim3hi exhaustion-prone effector T (TEX_EFF) cells or self-renewing Tcf1+Slamf6hiTim3lo precursor exhausted T (TPEX) cells. Here we showed that early CD8+ TEX cell fates were imprinted by forming subset-specific, self-associating chromatin hubs. Chromatin hub assembly coincided with effector or stemness gene induction and identified the transcription cofactors Id2 and Id3 as key regulators that promoted CD8+ TEX_EFF and CD8+ TPEX cell fates, respectively. Id2 drove CD8+ TEX_EFF cell specification by activating effector genes, while suppressing genes involved in exhaustion and stemness. In contrast, Id3-repressed effector genes but upregulated IL-7Rα and AhR, thereby maintaining the CD8+ TPEX cell pool. Mechanistically, Id2 and Id3 exhibited a distinct impact on the chromatin accessibility landscape in early CD8+ TEX cells by engaging Runx3 and Tcf1 transcription factors along with E proteins. These findings indicated that reshaping chromatin architecture represents a critical means for specifying CD8+ TEX cell fates and ensuring lineage stability.

Animals

Deciphering CD8+ T cell exhaustion in human cancers through single-cell and spatial transcriptomics.

Exhausted CD8+ T cells (Tex) within the tumor microenvironment (TME) represents a critical barrier limiting anti-tumor immune responses. Tex cells are characterized by upregulated inhibitory immune checkpoint receptors, reduced cytotoxicity, and functional heterogeneity. Their genomic features and regulatory networks remain poorly defined, and only a minority of patients respond to immune checkpoint blockade (ICB) therapy. Single-cell RNA sequencing (scRNA-seq), through high-resolution transcriptomic profiling, has revealed diverse Tex subpopulations, identified subpopulation-specific marker genes and regulatory pathways. Spatial transcriptomics has further mapped the spatial distribution of Tex and their interaction networks with immune cells, tumor cells, and stromal cells, elucidating the impact of spatial heterogeneity on Tex functionality. Current studies indicate that the exhausted state of Tex is dynamic and modifiable, with functional differences among subpopulations closely associated with tumor progression and therapeutic response. However, the genomic characteristics, epigenetic regulation, and spatial interaction mechanisms of Tex require further exploration. This review summarizes recent advances in high-resolution omics technologies for precisely dissecting Tex heterogeneity, functional features, and interactions with other cells. It emphasizes the central value of optimizing Tex-targeted tumor immunotherapy strategies, providing theoretical foundations and directional guidance for developing more effective anti-tumor immunotherapies.

Humans

Oncogene-induced matrix reorganization controls CD8+ T cell function in the soft-tissue sarcoma microenvironment.

CD8+ T cell dysfunction impedes antitumor immunity in solid cancers, but the underlying mechanisms are diverse and poorly understood. Extracellular matrix (ECM) composition has been linked to impaired T cell migration and enhanced tumor progression; however, impacts of individual ECM molecules on T cell function in the tumor microenvironment (TME) are only beginning to be elucidated. Upstream regulators of aberrant ECM deposition and organization in solid tumors are equally ill-defined. Therefore, we investigated how ECM composition modulates CD8+ T cell function in undifferentiated pleomorphic sarcoma (UPS), an immunologically active desmoplastic tumor. Using an autochthonous murine model of UPS and data from multiple human patient cohorts, we discovered a multifaceted mechanism wherein the transcriptional coactivator YAP1 promotes collagen VI (COLVI) deposition in the UPS TME. In turn, COLVI induces CD8+ T cell dysfunction and immune evasion by remodeling fibrillar collagen and inhibiting T cell autophagic flux. Unexpectedly, collagen I (COLI) opposed COLVI in this setting, promoting CD8+ T cell function and acting as a tumor suppressor. Thus, CD8+ T cell responses in sarcoma depend on oncogene-mediated ECM composition and remodeling.

CD8-Positive T-Lymphocytes

Senescent fibroblasts drive CD8+ T cell dysfunction in colorectal cancer via CD36-mediated lipid transfer and peroxidation.

BACKGROUND: Functional exhaustion of tumor-infiltrating CD8+ T cells represents a hallmark of colorectal cancer (CRC) immunosuppression, though its mechanistic drivers remain elusive. Given the established correlation between CRC progression and stromal senescence characterized by pathological lipid accumulation and impaired immunity, we investigated whether and how senescent fibroblasts actively regulate CD8+ T cell dysfunction. METHODS: Single-cell RNA sequencing (scRNA-seq) analysis was conducted to unveil the diverse fibroblast populations and the significant lipid metabolism changes between senescent fibroblasts and non-senescent fibroblasts in human CRC specimens and adjacent normal mucosa. Machine-learning identified senescent fibroblasts with a distinct gene signature. Cell-cell communication analysis was used to evaluate the interactions between senescent fibroblasts and CD8+ T cells in colorectal cancer. Co-culture experiments were conducted among senescent fibroblasts, CD8+ T cells and patient-derived organoids of CRC (CRC-PDOs), with the results evaluated with high-content imaging and propidium iodide/Hoechst 33,342 staining. Flow cytometry, ELISA and lipid pulse-chase with BODIPY FL C16 were performed to detect the alterations of CD8+ T cell cytotoxic function and metabolic status. AOM/DSS-induced CRC mouse model was used to conduct in vivo validation to evaluate whether senolytics could suppress CRC progression. Patients from the Cancer Genome Atlas colorectal cancer cohort were stratified into CD36-high and CD36-low groups by median expression, and drug sensitivity for GDSC2 compounds was predicted computationally using the oncoPredict R package. RESULTS: ScRNA-seq demonstrated the specific cell population presence and divergence of senescent fibroblasts between neoplastic and histologically normal adjacent cell clusters in CRC. Random Forest was employed for cell senescence classification. Feature importance analysis identified five genes as key contributors to the model’s decision process. Cell-cell communication analysis revealed enhanced interactions between senescent fibroblasts and CD8+ T cells in CRC. Co-culture of senescent fibroblasts significantly impaired the cytotoxic functions of CD8+ T cells on CRC-PDOs, which was reflected by the declined proportions of granzyme B (GZMB) + and interferon gamma (IFNγ) + CD8+ T cells and enhanced viability of CRC-PDOs. Mechanistically, the co-culture with senescent fibroblasts promoted the lipid shuttling into CD8+ T cells to induce lipid peroxidation and downstream impairment of cytotoxicity. Furthermore, the inhibition of CD36, the specific scavenger receptor for lipid uptake of CD8+ T cells, effectively suppressed lipid transfer and peroxidation thereby preserving the effector functions of CD8+ T cells and ultimately promoting tumor apoptosis. Complementarily, in vivo senolytic treatment significantly suppressed CRC progression in AOM-DSS CRC mouse models. Top 12 therapeutic agents were identified significantly enhanced predicted efficacy in CD36-high tumors. CONCLUSIONS: Our study identified a substantial population of senescent fibroblasts in human CRC through single cell transcriptomics, machine-learning and clinical biopsies. These senescent fibroblasts impair CD8+ T cell-mediated killing of CRC-PDOs via CD36-dependent lipid transfer, suggesting senolytic targeting of stromal cells as a promising immunotherapeutic strategy for CRC.

Colorectal Neoplasms

The MYC/TXNIP axis mediates NCL-Suppressed CD8+T cell immune response in lung adenocarcinoma.

BACKGROUND: Lung adenocarcinoma is a deadly malignancy with immune evasion playing a key role in tumor progression. Glucose metabolism is crucial for T cell function, and the nucleolar protein NCL may influence T cell glucose metabolism. This study aims to investigate NCL's role in T cell glucose metabolism and immune evasion by lung adenocarcinoma cells. METHODS: Utilizing single-cell RNA sequencing (scRNA-seq) data from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA), we analyzed cell clustering, annotation, and prognosis. In vitro experiments involved manipulating NCL expression in CD8+ T cells to study immune function and glucose metabolism. In vivo studies using an orthotopic transplant mouse model monitored NCL's impact on CD8+ T cell glucose metabolism and anti-tumor immune function. RESULTS: NCL was associated with T cell dysfunction and glucose metabolism. NCL silencing enhanced CD8+ T cell glucose metabolism, cytotoxicity, and infiltration, while NCL overexpression had the opposite effect. NCL overexpression relieved MYC-mediated transcriptional repression of TXNIP, reducing CD8+ T cell glucose metabolism. In vivo, NCL inhibited CD8+ T cell glucose metabolism through the MYC/TXNIP axis, hindering anti-tumor immune function. CONCLUSIONS: NCL overexpression suppresses CD8+ T cell glucose metabolism and anti-tumor immune function, promoting lung adenocarcinoma progression via the MYC/TXNIP axis.

CD8-Positive T-Lymphocytes

SLA2 is Associated With Immune evasion and Exhaustion of CD8+ T Cells in Gastric Cancer.

The Src-like adaptor 2 (SLA2) functions as a negative regulator of T cell receptor signalling. However, its involvement in the tumour microenvironment (TME) of gastric cancer (GC) remains unexplored. In this study, we found that SLA2 expression was significantly elevated in GC tissues, and a high level of SLA2 was associated with poor prognosis in GC patients. Bioinformatics analyses revealed a close association between SLA2 and TME in GC. Single-cell RNA sequencing analysis indicated that SLA2 was significantly enriched in CD8+ T cells in GC tissues. Functional validation demonstrated that SLA2 overexpression contributed to the exhaustion of CD8+ T cells by suppressing their proliferation, upregulating the expression of exhaustion markers, reducing the secretion of effector cytokines (IFN-γ and TNF-α) and impairing cytotoxic function. SLA2 knockdown in in vitro-generated exhausted CD8 T cells significantly alleviated T cell exhaustion. Mechanistically, we found that inverse promoter methylation and active histone marks (H3K27ac, H3K4me3 and H3K4me1) may regulate SLA2 expression. Our findings suggest that SLA2 may modulate the TME and promote immune evasion via CD8+ T cell exhaustion in GC.

Humans

Priming of CD8+ T cells by peripheral dendritic cells exacerbates tau-mediated neurodegeneration.

Alzheimer's disease and primary tauopathies are marked by changes in adaptive immunity, with increased brain CD8+ T cells correlating with tau pathology severity. However, how peripheral T cells get primed to enter the brain and contribute to tau-mediated neurodegeneration remains unclear. In different disease conditions, conventional type 1 dendritic cells (cDC1s) cross-present antigens to prime CD8+ T cells into effector cells. We show that tauopathy mice lacking cDC1s or antigen cross-presentation are protected from neurodegeneration, with reduced brain CD8+ T cell infiltration and glial activation. The remaining CD8+ T cells exhibit limited clonal expansion, consistent with impaired priming. We further demonstrate that brain-derived antigens are presented in secondary lymphoid tissues, suggesting a site of T cell activation. Together, these findings establish cDC1-dependent peripheral priming as a key driver of CD8+ T cell accumulation in the brain and tau-mediated neurodegeneration.

Journal Article

Malonate promotes CD8+ T cell memory formation via protein malonylation.

Protein malonylation represents a recently identified posttranslational modification whose role in CD8+ T cell differentiation and functionality remains incompletely understood. In this study, we demonstrate that enhancing protein malonylation through sodium malonate (SM) treatment promotes CD8+ T cell memory formation in response to bacterial infection, subsequently potentiating recall responses. Comparative metabolomic analysis between SM-treated and control CD8+ T cells revealed significant metabolic alterations associated with protein malonylation. We present the first comprehensive proteomic analysis of lysine malonylation in murine CD8+ T cells, identifying 77 malonylation sites across 64 proteins involved in diverse cellular processes, particularly metabolic pathways. Malonylation of STAT6 was confirmed via the use of a specific chemical probe. Notably, we established that malonylation at the lysine 374 site of STAT6 results in increased TCF1 expression, due to alleviated transcriptional repression of TCF1 by STAT6. Collectively, our findings provide compelling evidence that protein malonylation plays a significant role in regulating CD8+ T cell memory formation.

Animals

Intratumoral PD-1+LAG-3+CD8+ T cells are associated with improved prognosis in gastric cancer.

PURPOSE: PD-1 and LAG-3 are frequently used as markers of T cell exhaustion, yet the prognostic relevance and phenotypic characteristics of PD-1+LAG-3+CD8+ T cells in gastric cancer (GC) remain poorly defined. This study aimed to investigate their association with clinical outcomes and characterize their immune characteristics across independent GC cohorts. METHODS: Four independent GC cohorts were analyzed: the Zhongshan Hospital cohort (ZSGC, n = 298), The Cancer Genome Atlas cohort (TCGA, n = 371), an Immune Checkpoint Blockade cohort (ICB, n = 45), and the Yonsei cohort (n = 433). Intratumoral PD-1+LAG-3+CD8+ T cell infiltration was quantified by immunofluorescence staining and transcriptomic gene signature scoring. Survival analysis was performed using Kaplan-Meier estimation and multivariate Cox regression. Functional characterization was performed by flow cytometry on resected GC tissue. The immune microenvironment composition was evaluated using computational analyses. RESULTS: PD-1+LAG-3+CD8+ T cells were enriched within tumors compared to adjacent normal mucosa, and their infiltration correlated with advanced tumor stage, poor differentiation, microsatellite instability, and Epstein-Barr virus (EBV)-positive molecular subtypes. High intratumoral infiltration was significantly associated with improved overall survival in both the ZSGC and TCGA cohorts, whereas single-positive PD-1+CD8+ or LAG-3+CD8+ T cells showed no such association. In the ICB cohort, higher infiltration was associated with a higher response rate to pembrolizumab. Intratumoral PD-1+LAG-3+CD8+ T cells exhibit an activated phenotype characterized by increased expression of CD137, IFN-γ, perforin, and CXCL13, along with elevated TCF7 and lower PD-1 levels, suggesting a tumor-reactive, pre-exhausted state. High infiltration was further associated with an immune-active tumor microenvironment. CONCLUSIONS: High intratumoral infiltration of PD-1+LAG-3+CD8+ T cells is associated with favorable prognosis and an immune-active microenvironment in GC. These cells display phenotypic features consistent with a pre-exhausted state and may serve as independent prognostic biomarkers and candidate predictive biomarkers for immunotherapy stratification.

Humans

Intrathecally expanded GZMK+/GZMH+ CD8 T cells targeting EBV antigens may reduce severity of Multiple Sclerosis.

Combining cerebrospinal fluid B cell receptor and T cell receptor repertoire analysis with transcriptional/ flow cytometry cellular profiles in hundreds of deeply-phenotyped people with Multiple Sclerosis (pwMS) and controls, we identified intrathecal expansion of anti-viral, cytotoxic, granzymes H/K (GZMH+/GZMK+) double positive (DP) CD8+ T cells that recognize EBV epitopes in pwMS. DP CD8+ T cells are activated and expanded by, and kill autologous, EBV-infected CSF B cell lines in-vitro. Correlations of surrogate transcriptional profiles with clinical and imaging outcomes infer a beneficial role for EBV-targeting DP CD8+ T cells, as untreated pwMS with proportionally higher DP CD8+ T cells to intrathecal B cells accumulate neurological disability slower. MS therapies also increase ratios of beneficial CD8+ T cell responses to intrathecal B cells, consistent with their ability to inhibit disability progression. This study provides indirect evidence that intrathecal EBV infection participates in disability accumulation in pwMS.

Journal Article

Exhausted CD8+ T cell fate is programmed by dynamic CTCF-mediated enhancer activation and invariant CTCF-imposed barriers.

Exhausted CD8+ T (TEX) cells undergo extensive genome reorganization during differentiation, yet the drivers of this process remain elusive. Here we show that CTCF programmed CD8+ TEX cell fates through two distinct modes of action. CTCF acquired de novo binding sites and concordantly induced open chromatin in early CD8+ TEX cells responding to chronic viral infection. The dynamic CTCF binding activated enhancers and promoted chromatin looping. Consequently, genetic ablation of CTCF diminished chromatin accessibility and interaction strength, impairing CD8+ TEX cell proliferation, effector function and bioenergetic mobilization. Conversely, invariant CTCF binding acted as essential chromatin barriers, and loss of CTCF disrupted insulation and caused aberrant chromatin self-association and undue RNA polymerase II pausing, leading to excessive activation of exhaustion- and stemness-linked genes. Thus, CTCF balanced CD8+ TEX cell differentiation by gaining dynamic binding to induce cytotoxicity and sustain metabolic fitness, while its invariant binding compartmentalized exhaustion and stemness program genes to prevent their overexuberant activation.

CCCTC-Binding Factor

Multi-level aggregation analysis of microbiome composition and host gene expression reveals associations with systemic and local immunity.

The human gut microbiome plays a critical role in immune regulation, yet the molecular links between microbiome composition and host gene expression remain incompletely understood. We analyzed associations between host gene expression and microbiome composition in a cohort of 315 healthy individuals, integrating microarray-based gene expression data from three intestinal sites (ileum, transverse colon, and rectum) and six immune cell types with microbiome sequencing data. Using a hierarchical feature aggregation strategy combining principal component analysis, clustering, and covariate correction, we discovered significant associations primarily related to immunity. While microbial profiles were similar across the three intestinal sites, the transverse colon yielded the most "microbiome-host gene expression" associations. Among the immune cell types, CD8+ cells showed the highest number of associations. The first principal component of microbiome composition, reflecting a gradient from commensals (e.g., Ruminococcaceae and Christensenellaceae) to proinflammatory taxa ([Ruminococcus] gnavus and Lachnoclostridium), correlated with the expression of TNF-α-linked genes (HMOX1, CPI17, HSD3B2, and SLC5A1). Among individual genera, Catenibacterium abundance was associated with gene expression in both intestinal and immune cells, including negative associations with MRPS21 (related to mitochondrial function) in the transverse colon and with CD8+ gene programs related to T cell differentiation. These findings align with emerging evidence implicating mitochondrial dysfunction in intestinal inflammation. Our results identify multi-level associations between the gut microbiome and host gene expression, suggesting potential mechanisms by which microbiota shape local and systemic immunity and vice versa. The implicated genes and taxa represent candidates for experimental validation to improve understanding of host-microbiome homeostasis and its disruption in disease.IMPORTANCEThe gut microbiome and immune system are engaged in a complex interplay throughout human life. While most associative studies focus on case-control comparisons-typically examining patients with conditions such as inflammatory bowel disease or metabolic diseases-less is known about the molecular links between the microbiome and immune system in healthy individuals. In this study of a large cohort of healthy individuals, we addressed this gap by applying multiscale modeling to tackle the high dimensionality of host-microbiome data. We identified multi-level associations between microbiome composition and host gene expression in both intestinal tissues and immune cells. These findings offer a valuable reference for understanding baseline host-microbiome communication and highlight molecular candidates-such as TNF-α-related genes and mitochondrial pathways-for future experimental validation.

Humans

CTSG Suppresses Breast Cancer Progression by Inhibiting the EGFR/ERK Signaling Pathway and Enhancing CD8⁺ T Cell Activation.

BACKGROUND: Breast cancer (BC), the most common female malignancy, has metastasis as its main cause of mortality. Cathepsin G (CTSG) is involved in tumorigenesis and immunity. This study explores the role of CTSG in BC progression and CD8 + T cell regulation. METHODS: Differentially expressed genes and proteins (DEGs/DEPs) were analyzed using Limma, and core genes were screened using Random Forest (RF) and Least absolute shrinkage and selection operator (LASSO). CTSG expression was analyzed using GSE36295, the Cancer Genome Atlas (TCGA), reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and western blot. Cell viability, proliferation, cell cycle, migration, and invasion were detected using Cell Counting Kit-8 (CCK8), 5&#x2011;Ethynyl&#x2011;2'&#x2011;deoxyuridine (EdU), flow cytometry, and Transwell assays, respectively. Sphere diameter was analyzed via sphere formation assay. Downstream mechanisms were examined using western blot, CCK8, flow cytometry, and Transwell assays. CD8 + T cell activity was examined using EdU, western blot, and flow cytometry. RESULTS: A total of 177 genes overlapped between GSE36295 DEGs and PDC000173 DEPs. CTSG was the hub gene identified by RF and LASSO. CTSG expression was significantly reduced in BC (P < 0.01). CTSG overexpression suppressed cell viability, proliferation, migration, invasion, sphere formation, and CD44 and CD133 expression (P < 0.01). CTSG up-regulation inhibited epidermal growth factor receptor (EGFR)/extracellular signal-regulated kinase (ERK) signaling axis and reduced cancer cell malignancy (P < 0.01). CTSG overexpression activated CD8 + T cells via EGFR/ERK inhibition, enhancing their cytotoxic effect on cancer cells (P < 0.01). CONCLUSION: CTSG inhibits BC malignancy and enhances CD8 + T cell function via EGFR/ERK inhibition.

Humans