The inhibitory receptor TIM-3 limits activation of the cGAS-STING pathway in intra-tumoral dendritic cells by suppressing extracellular DNA uptake.

Blockade of the inhibitory receptor TIM-3 shows efficacy in cancer immunotherapy clinical trials. TIM-3 inhibits production of the chemokine CXCL9 by XCR1+ classical dendritic cells (cDC1), thereby limiting antitumor immunity in mammary carcinomas. We found that increased CXCL9 expression by splenic cDC1s upon TIM-3 blockade required type I interferons and extracellular DNA. Chemokine expression as well as combinatorial efficacy of TIM-3 blockade and paclitaxel chemotherapy were impaired by deletion of Cgas and Sting. TIM-3 blockade increased uptake of extracellular DNA by cDC1 through an endocytic process that resulted in cytoplasmic localization. DNA uptake and efficacy of TIM-3 blockade required DNA binding by HMGB1, while galectin-9-induced cell surface clustering of TIM-3 was necessary for its suppressive function. Human peripheral blood cDC1s also took up extracellular DNA upon TIM-3 blockade. Thus, TIM-3 regulates endocytosis of extracellular DNA and activation of the cytoplasmic DNA sensing cGAS-STING pathway in cDC1s, with implications for understanding the mechanisms underlying TIM-3 immunotherapy.

Activation of p53 in Immature Myeloid Precursor Cells Controls Differentiation into Ly6c+CD103+ Monocytic Antigen-Presenting Cells in Tumors.

CD103+ dendritic cells are critical for cross-presentation of tumor antigens. Here we have shown that during immunotherapy, large numbers of cells expressing CD103 arose in murine tumors via direct differentiation of Ly6c+ monocytic precursors. These Ly6c+CD103+ cells could derive from bone-marrow monocytic progenitors (cMoPs) or from peripheral cells present within the myeloid-derived suppressor cell (MDSC) population. Differentiation was controlled by inflammation-induced activation of the transcription factor p53, which drove upregulation of Batf3 and acquisition of the Ly6c+CD103+ phenotype. Mice with a targeted deletion of p53 in myeloid cells selectively lost the Ly6c+CD103+ population and became unable to respond to multiple forms of immunotherapy and immunogenic chemotherapy. Conversely, increasing p53 expression using a p53-agonist drug caused a sustained increase in Ly6c+CD103+ cells in tumors during immunotherapy, which markedly enhanced the efficacy and duration of response. Thus, p53-driven differentiation of Ly6c+CD103+ monocytic cells represents a potent and previously unrecognized target for immunotherapy.

Tertiary Lymphoid Structure-Associated B Cells Enhance CXCL13+CD103+CD8+ Tissue-Resident Memory T-Cell Response to Programmed Cell Death Protein 1 Blockade in Cancer Immunotherapy.

BACKGROUND & AIMS: Although the presence of tertiary lymphoid structures (TLS) correlates with positive responses to immunotherapy in many solid malignancies, the mechanism by which TLS enhances antitumor immunity is not well understood. The present study aimed to investigate the underlying cross talk circuits between B cells and tissue-resident memory T (Trm) cells within the TLS and to understand their role in the context of immunotherapy. METHODS: Immunostaining and H&E staining of TLS and chemokine (C-X-C motif) ligand 13 (CXCL13)+ cluster of differentiation (CD)103+CD8+ Trm cells were performed on tumor sections from patients with gastric cancer (GC). The mechanism of communication between B cells and CXCL13+CD103+CD8+ Trm cells was determined in vitro and in vivo. The effect of CXCL13+CD103+CD8+ Trm cells in suppressing tumor growth was evaluated through anti-programmed cell death protein (PD)-1 therapy. RESULTS: The presence of TLS and CXCL13+CD103+CD8+ Trm cells in tumor tissues favored a superior response to anti-PD-1 therapy in patients with GC. Additionally, our research identified that activated B cells enhanced CXCL13 and granzyme B secretion by CD103+CD8+ Trm cells. Mechanistically, B cells facilitated the glycolysis of CD103+CD8+ Trm cells through the lymphotoxin-α/tumor necrosis factor receptor 2 (TNFR2) axis, and the mechanistic target of rapamycin signaling pathway played a critical role in CD103+CD8+ Trm cells glycolysis during this process. Moreover, the presence of TLS and CXCL13+CD103+CD8+ Trm cells correlated with potent responsiveness to anti-PD-1 therapy in a TNFR2-dependent manner. CONCLUSIONS: This study further reveals a crucial role for cellular communication between TLS-associated B cell and CXCL13+CD103+CD8+ Trm cells in antitumor immunity, providing valuable insights into the potential use of the lymphotoxin-α/TNFR2 axis within CXCL13+CD103+CD8+ Trm cells for advancing immunotherapy strategies in GC.

Cognate antigen-independent differentiation of resident memory T cells in chronic kidney disease.

Resident memory T cells (TRMs), which are memory T cells that are retained locally within tissues, have recently been described as antigen-specific frontline defenders against pathogens in barrier and nonbarrier epithelial tissues. They have also been noted for perpetuating chronic inflammation. The conditions responsible for TRM differentiation are still poorly understood, and their contributions, if any, to sterile models of chronic kidney disease (CKD) remain a mystery. In this study, we subjected male C57BL/6J mice and OT-1 transgenic mice to five consecutive days of 2 mg/kg aristolochic acid (AA) injections intraperitoneally to induce CKD or saline injections as a control. We evaluated their kidney immune profiles at 2 wk, 6 wk, and 6 mo after treatment. We identified a substantial population of TRMs in the kidneys of mice with AA-induced CKD. Flow cytometry of injured kidneys showed T cells bearing TRM surface markers and single-cell (sc) RNA sequencing revealed these cells as expressing well-known TRM transcription factors and receptors responsible for TRM differentiation and maintenance. Although kidney TRMs expressed Cd44, a marker of antigen experience and T cell activation, their derivation was independent of cognate antigen-T cell receptor interactions, as the kidneys of transgenic OT-1 mice still harbored considerable proportions of TRMs after injury. Our results suggest a nonantigen-specific or antigen-independent mechanism capable of generating TRMs in the kidney and highlight the need to better understand TRMs and their involvement in CKD.NEW & NOTEWORTHY Resident memory T cells (TRMs) differentiate and are retained within the kidneys of mice with aristolochic acid (AA)-induced chronic kidney disease (CKD). Here, we characterized this kidney TRM population and demonstrated TRM derivation in the kidneys of OT-1 transgenic mice with AA-induced CKD. A better understanding of TRMs and the processes by which they can differentiate independent of antigen may help our understanding of the interactions between the immune system and kidneys.

CD8 + CD103 + iTregs protect against ischemia-reperfusion-induced acute kidney Injury by inhibiting pyroptosis.

The occurrence of acute kidney injury (AKI) is elevated, one of the main causes is ischemia-reperfusion (I/R). However, no specific therapy is currently available to treat I/R-induced AKI (I/R-AKI). Treg cells have been demonstrated to perform an anti-inflammatory role in a range of autoimmune and inflammatory illnesses. However, there is limited available information about the possible functions of CD8 + CD103 + iTregs in I/R-AKI. We utilized renal tubular epithelial cells (RTECs) subjected to hypoxia-reoxygenation (H/R) and I/R-AKI mouse model to investigate whether CD8 + CD103 + iTregs could attenuate AKI and the underlying mechanism. In vitro, co-cultured with CD8 + CD103 + iTregs alleviated H/R-induced cell injury. After treatment of CD8 + CD103 + iTregs rather than control cells, a significant improvement of I/R-AKI was observed in vivo, including decreased serum creatinine (sCr) and blood urea nitrogen (BUN) levels, reduced renal pathological injury, lowered tubular apoptosis and inhibition of the transition from AKI to chronic kidney disease (CKD). Mechanically, CD8 + CD103 + iTregs alleviated H/R-induced cell injury and I/R-AKI partly by suppressing RTECs pyroptosis via inhibiting the NLRP3/Caspase-1 axis. Our study provides a novel perspective on the possibility of CD8 + CD103 + iTregs for the treatment of I/R-AKI.

Tissue-resident memory T cells exhibit phenotypically and functionally heterogeneous in human physiological and pathological nasal mucosa.

Pathogens commonly enter mucosal barrier tissues and tissue-resident memory T cells (TRM) are essential for preventing mucosal lesions. However, the immunological properties of TRM cells in nasal mucosa are poorly known. In comparison with control tissues, decreasing CD103+ TRM cells were observed in Chronic rhinosinusitis with nasal polyps (CRSwNPs) and sinonasal inverted papilloma (SNIP), which presented high capability to produce effector cytokines. In CRSwNPs, we found that CD103+ TRM cells with higher cytokine and Granzyme B coexpressed high PD-1, CD103- TRM cells expressed higher IL-10. Homogenates isolated from CRSwNPs induced CD103 expression on peripheral T cells which could be inhibited by blocking TGF-ß. The frequencies of CD103+ TRM cells in CRSwNPs were extremely negatively correlated with neutrophil infiltration. CD103+ TRM cells from Staphylococcus aureus positive CRSwNPs had a stronger response to SEB. Taken together, two phenotypically and functionally distinct subsets of TRM cells exist in nasal tissues and play critical roles in the progress of CRSwNPs and SNIPs.

Spatial Distribution and Densities of CD103+ and FoxP3+ Tumor Infiltrating Lymphocytes by Digital Analysis for Outcome Prediction in Breast Cancer.

BACKGROUND: The evaluation of tumor-infiltrating lymphocytes (TILs) for breast cancer prognosis is now established. However, the clinical value for their spatial distributions of specific immune subsets, namely CD103+ tissue-resident memory T cells FoxP3+ regulatory T ells, have not been thoroughly examined. METHOD: Representative whole sections of breast cancers were subjected to CD103 and FoxP3 double staining. Their density, ratio, and spatial features were analyzed in tumor area and tumor-stromal interface. Their associations with clinicopathological parameters and patient's prognosis were analyzed. RESULTS: CD103 TILs were closer to tumor nests than FoxP3 TILs in the tumor-stromal interface. Their densities were associated with high-grade disease, TNBC, and stromal TILs. High stromal FoxP3 (sFoxP3) TILs and close proximity of sCD103 TILs to tumor were independently associated with better survival at multivariate analysis. Subgroup analysis showed the high FoxP3 TILs density associated better survival was seen in HER2-OE and TNBC subtypes while the proximity of CD103 TILs to tumor nests associated better survival was seen in luminal cancers. CONCLUSION: The prognostic impact of CD103 and FoxP3 TILs in breast cancer depends on their spatial localization. High sFoxP3 TIL density and the lower distance of CD103 TILs from the tumor nests had independent favorable prognostic values.

Tissue-resident memory CD103+CD8+ T cells in colorectal cancer: its implication as a prognostic and predictive liver metastasis biomarker.

BACKGROUND: Tissue-resident memory CD103+CD8+ T cells (CD103+CD8+ TRMs) are important components of anti-tumor immunity. However, the significance of CD103+CD8+ TRMs in colorectal cancer (CRC) and their advantages remain unclear. METHODS: Clinical data and specimens were used to evaluate the significance of CD103+CD8+ TRMs in CRC. A mouse subcutaneous tumorigenesis model and colony-formation assay were conducted to evaluate the anti-tumor effects of CD103+CD8+ TRMs. Finally, the infiltration density and function of CD103+CD8+ TRMs in the tumors were evaluated using flow cytometry. RESULTS: In this study, we showed that highly infiltrated CD103+CD8+ TRMs were associated with earlier clinical stage and negative VEGF expression in CRC patients and predicted a favorable prognosis for CRC/CRC liver metastases patients. Interestingly, we also found that CD103+CD8+ TRMs may have predictive potential for whether CRC develops liver metastasis in CRC. In addition, we found a positive correlation between the ratio of the number of α-SMA+ vessels to the sum of the number of α-SMA+ and CD31+ vessels in CRC, and the infiltration level of CD103+CD8+ TRMs. In addition, anti-angiogenic therapy promoted infiltration of CD103+CD8+ TRMs and enhanced their ability to secrete interferon (IFN)-γ, thus further improving the anti-tumor effect. Moreover, in vivo experiments showed that compared with peripheral blood CD8+ T cells, CD103+CD8+ TRMs infused back into the body could also further promote CD8+ T cells to infiltrate the tumor, and they had a stronger ability to secrete IFN-γ, which resulted in better anti-tumor effects. CONCLUSION: We demonstrated that CD103+CD8+ TRMs have the potential for clinical applications and provide new ideas for combined anti-tumor therapeutic strategies, such as anti-tumor angiogenesis therapy and CAR-T combined immunotherapy.

Spatial features of specific CD103+CD8+ tissue-resident memory T cell subsets define the prognosis in patients with non-small cell lung cancer.

BACKGROUND: Tissue-resident memory T (TRM) cells can reside in the tumor microenvironment and are considered the primary response cells to immunotherapy. Heterogeneity in functional status and spatial distribution may contribute to the controversial role of TRM cells but we know little about it. METHODS: Through multiplex immunofluorescence (mIF) (CD8, CD103, PD-1, Tim-3, GZMB, CK), the quantity and spatial location of TRM cell subsets were recognized in the tissue from 274 patients with NSCLC after radical surgery. By integrating multiple machine learning methods, we constructed a TRM-based spatial immune signature (TRM-SIS) to predict the prognosis. Furthermore, we conducted a CD103-related gene set enrichment analysis (GSEA) and verified its finding by another mIF panel (CD8, CD103, CK, CD31, Hif-1α). RESULTS: The density of TRM cells was significantly correlated with the expression of PD-1, Tim-3 and GZMB. Four types of TRM cell subsets was defined, including TRM1 (PD-1-Tim-3-TRM), TRM2 (PD-1+Tim-3-TRM), TRM3 (PD-1-Tim-3+TRM) and TRM4 (PD-1+Tim-3+TRM). The cytotoxicity of TRM2 was the strongest while that of TRM4 was the weakest. Compare with TRM1 and TRM2, TRM3 and TRM4 had better infiltration and stronger interaction with cancer cells. The TRM-SIS was an independent prognostic factor for disease-free survival [HR = 2.43, 95%CI (1.63-3.60), P < 0.001] and showed a better performance than the TNM staging system for recurrence prediction. Furthermore, by CD103-related GSEA and mIF validation, we found a negative association between tumor angiogenesis and infiltration of TRM cells. CONCLUSIONS: These findings reveal a significant heterogeneity in the functional status and spatial distribution of TRM cells, and support it as a biomarker for the prognosis of NSCLC patients. Regulating TRM cells by targeting tumor angiogenesis may be a potential strategy to improve current immunotherapy.

Immunological characteristics of CD103+CD161+ T lymphocytes on chronic rhinosinusitis with nasal polyps.

Chronic rhinosinusitis with nasal polyps (CRSwNPs) is a heterogeneous disease characterized by local inflammation of the upper airway and sinus mucosa. T cell-mediated immune responses play irreplaceable roles in the pathogenesis of nasal polyps. CD161+ T cells have been implicated in the pathology of several diseases through cytokine production and cytotoxic activity. However, the immunological characteristics of CD161+ T cells in nasal mucosa are still not well understood, particularly in CRSwNPs. Our research revealed a notable enrichment of CD161+ T cells in nasal tissues compared to peripheral blood, with a significantly more infiltration of CD161+ T cells in CRSwNPs compared to control nasal samples. Phenotypical analysis found that CD161+ T cells predominantly co-expressed tissue-resident memory surface markers CD103, CD69, and CD45RO. CD161+CD103+ T cells demonstrated complicated effector functions, marked by elevated levels of PD-1, CTLA-4, IL-17, and IFN-γ and diminished expression of FoxP3 and CD25. Interestingly, despite CD161+ T cells was more abundant in polyp tissues compared to normal control tissues, and then further categorizing polyp samples into distinct groups based on clinical characteristics, only the recurrent CRSwNP group showed a significant reduction in CD161+CD8+ T cells compared to the primary CRSwNP group. This finding suggested the necessity for further research to comprehensively understand the underlying mechanisms and the broader significance of CD161+ T cells in the advancement and relapse of CRSwNPs.

Prognostic relevance of tumor-resident memory T cells in metastatic lymph nodes of esophageal squamous cell carcinoma.

Tumor-resident memory T (TRM ) cells in primary tumors are reportedly associated with a favorable prognosis in several malignancies. However, the behaviors and functions of TRM cells in regional lymph nodes (LNs) of esophageal cancer remain poorly understood. The aim of this study was to elucidate the effects of TRM cells in regional LNs of esophageal cancer on clinicopathological findings and prognosis. Specimens of esophageal cancer and primary metastatic LNs (recurrent nerve LNs) were obtained from 84 patients who underwent radical esophagectomy between 2011 and 2017. We performed immunohistochemistry to enumerate and analyze TRM cells, and used flow cytometry to investigate the function of TRM cells. TRM cells were observed in both metastatic LNs and primary tumors. TRM cell-rich specimens exhibited reduced lymphatic invasion and LN metastasis and prolonged survival compared with TRM cell-poor specimens. TRM cells in metastatic LNs were more significantly associated with enhanced survival than TRM cells in primary tumors. TRM cells expressed high levels of granzyme B as a cytotoxicity marker. Our results suggested that high TRM cell infiltration in metastatic LNs improves survival even though LN metastasis is commonly associated with poor prognosis. TRM cells possibly contribute to antitumor immunity in regional LNs.

Attenuation of renal injury by depleting cDC1 and by repurposing Flt3 inhibitor in anti-GBM disease.

Previous studies found cDC1s to be protective in early stage anti-GBM disease through Tregs, but pathogenic in late stage Adriamycin nephropathy through CD8+ T cells. Flt3 ligand is a growth factor essential for cDC1 development and Flt3 inhibitors are currently used for cancer treatment. We conducted this study to clarify the role and mechanisms of effects of cDC1s at different time points in anti-GBM disease. In addition, we aimed to utilize drug repurposing of Flt3 inhibitors to target cDC1s as a treatment of anti-GBM disease. We found that in human anti-GBM disease, the number of cDC1s increased significantly, proportionally more than cDC2s. The number of CD8+ T cells also increased significantly and their number correlated with cDC1 number. In XCR1-DTR mice, late (day 12-21) but not early (day 3-12) depletion of cDC1s attenuated kidney injury in mice with anti-GBM disease. cDC1s separated from kidneys of anti-GBM disease mice were found to have a pro-inflammatory phenotype (i.e. express high level of IL-6, IL-12 and IL-23) in late but not early stage. In the late depletion model, the number of CD8+ T cells was also reduced, but not Tregs. CD8+ T cells separated from kidneys of anti-GBM disease mice expressed high levels of cytotoxic molecules (granzyme B and perforin) and inflammatory cytokines (TNF-α and IFN-γ), and their expression reduced significantly after cDC1 depletion with diphtheria toxin. These findings were reproduced using a Flt3 inhibitor in wild type mice. Therefore, cDC1s are pathogenic in anti-GBM disease through activation of CD8+ T cells. Flt3 inhibition successfully attenuated kidney injury through depletion of cDC1s. Repurposing Flt3 inhibitors has potential as a novel therapeutic strategy for anti-GBM disease.

Systematic analysis of CD39, CD103, CD137, and PD-1 as biomarkers for naturally occurring tumor antigen-specific TILs.

The detection of tumor-specific T cells in solid tumors is integral to interrogate endogenous antitumor responses and to advance downstream therapeutic applications. Multiple biomarkers are reported to identify endogenous tumor-specific tumor-infiltrating lymphocytes (TILs), namely CD137, PD-1, CD103, and CD39; however, a direct comparison of these molecules has yet to be performed. We evaluated these biomarkers in primary human ovarian tumor samples using single-cell mass cytometry to compare their relative phenotypic profiles, and examined their response to autologous tumor cells ex vivo. PD-1+ , CD103+ , and CD39+ TILs all contain a CD137+ cell subset, while CD137+ TILs highly co-express the aforementioned markers. CD137+ TILs exhibit the highest expression of cytotoxic effector molecules compared to PD-1+ , CD103+ , or CD39+ TILs. Removal of CD137+ cells from PD-1+ , CD103+ , or CD39+ TILs diminish their IFN-γ secretion in response to autologous tumor cell stimulation, while CD137+ TILs maintain high HLA-dependent IFN-γ secretion. CD137+ TILs exhibited an exhausted phenotype but with CD28 co-expression, suggesting possible receptiveness to reinvigoration via immune checkpoint blockade. Together, our findings demonstrate that the antitumor abilities of PD-1+ , CD103+ , and CD39+ TILs are mainly derived from a subset of CD137-expressing TILs, implicating CD137 as a more selective biomarker for naturally occurring tumor-specific TILs.

The tissue-resident marker CD103 on peripheral blood T cells predicts responses to anti-PD-1 therapy in gastric cancer.

BACKGROUND: Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment. Since clinical benefits are limited to a subset of patients, we aimed to identify peripheral blood biomarkers that predict the efficacy of the anti-programmed cell death protein 1 (PD-1) antibody (nivolumab) in patients with gastric cancer. METHODS: We collected peripheral blood samples from gastric cancer patients (n = 29) before and after treatment with nivolumab and investigated the relationship between the frequency of surface or intracellular markers among nivolumab-binding PD-1+CD8+ T cells and treatment responses using multicolor flow cytometry. The tumors, lymph nodes, and peripheral blood of gastric cancer patients who underwent gastrectomy following nivolumab treatment were collected, and nivolumab-binding PD-1+CD8+ T cells in these tissue samples were characterized. RESULTS: Patients with a high frequency of CD103 among PD-1+CD8+ T cells in peripheral blood 2 weeks after the start of treatment had significantly better progression-free survival than the low group (P = 0.032). This CD103+PD-1+CD8+ T cell population mainly consisted of central memory T cells, showing the high expression of Ki-67 and few cytotoxic granules. In contrast, effector memory T cells were more frequently observed among CD103+PD-1+CD8+ T cells in tumors, which implied a change in the differentiated status of central memory T cells in lymph nodes and peripheral blood to effector memory T cells in tumors during the treatment with ICIs. CONCLUSIONS: A high frequency of CD103 among PD-1+CD8+ T cells 2 weeks after nivolumab treatment in patients with advanced gastric cancer may be a useful biomarker for predicting the efficacy of anti-PD-1 therapy.

The expression profiles of signature genes from CD103+LAG3+ tumour-infiltrating lymphocyte subsets predict breast cancer survival.

BACKGROUND: Tumour-infiltrating lymphocytes (TILs), including T and B cells, have been demonstrated to be associated with tumour progression. However, the different subpopulations of TILs and their roles in breast cancer remain poorly understood. Large-scale analysis using multiomics data could uncover potential mechanisms and provide promising biomarkers for predicting immunotherapy response. METHODS: Single-cell transcriptome data for breast cancer samples were analysed to identify unique TIL subsets. Based on the expression profiles of marker genes in these subsets, a TIL-related prognostic model was developed by univariate and multivariate Cox analyses and LASSO regression for the TCGA training cohort containing 1089 breast cancer patients. Multiplex immunohistochemistry was used to confirm the presence of TIL subsets in breast cancer samples. The model was validated with a large-scale transcriptomic dataset for 3619 breast cancer patients, including the METABRIC cohort, six chemotherapy transcriptomic cohorts, and two immunotherapy transcriptomic cohorts. RESULTS: We identified two TIL subsets with high expression of CD103 and LAG3 (CD103+LAG3+), including a CD8+ T-cell subset and a B-cell subset. Based on the expression profiles of marker genes in these two subpopulations, we further developed a CD103+LAG3+ TIL-related prognostic model (CLTRP) based on CXCL13 and BIRC3 genes for predicting the prognosis of breast cancer patients. CLTRP-low patients had a better prognosis than CLTRP-high patients. The comprehensive results showed that a low CLTRP score was associated with a high TP53 mutation rate, high infiltration of CD8 T cells, helper T cells, and CD4 T cells, high sensitivity to chemotherapeutic drugs, and a good response to immunotherapy. In contrast, a high CLTRP score was correlated with a low TP53 mutation rate, high infiltration of M0 and M2 macrophages, low sensitivity to chemotherapeutic drugs, and a poor response to immunotherapy. CONCLUSIONS: Our present study showed that the CLTRP score is a promising biomarker for distinguishing prognosis, drug sensitivity, molecular and immune characteristics, and immunotherapy outcomes in breast cancer patients. The CLTRP could serve as a valuable tool for clinical decision making regarding immunotherapy.

Research progress on intestinal tissue-resident memory T cells in inflammatory bowel disease.

Tissue-resident memory T (TRM) cells are a recently discovered subpopulation of memory T cells that reside in non-lymphoid tissues such as the intestine and skin and do not enter the bloodstream. The intestine encounters numerous pathogens daily. Intestinal mucosal immunity requires a balance between immune responses to pathogens and tolerance to food antigens and symbiotic microbiota. Therefore, intestinal TRM cells exhibit unique characteristics. In healthy intestines, TRM cells induce necessary inflammation to strengthen the intestinal barrier and inhibit bacterial translocation. During intestinal infections, TRM cells rapidly eliminate pathogens by proliferating, releasing cytokines, and recruiting other immune cells. Moreover, certain TRM cell subsets may have regulatory functions. The involvement of TRM cells in inflammatory bowel disease (IBD) is increasingly recognized as a critical factor. In IBD, the number of pro-inflammatory TRM cells increases, whereas the number of regulatory subgroups decreases. Additionally, the classic markers, CD69 and CD103, are not ideal for intestinal TRM cells. Here, we review the phenotype, development, maintenance, and function of intestinal TRM cells, as well as the latest findings in the context of IBD. Further understanding of the function of intestinal TRM cells and distinguishing their subgroups is crucial for developing therapeutic strategies to target these cells.

Significance of CD103+ tissue-resident memory T cells for predicting the effectiveness of immune checkpoint inhibitors in esophageal cancer.

BACKGROUND: Immune checkpoint inhibitors (ICIs), including nivolumab, have been approved to treat esophageal cancer. However, these remedies are not fit for all patients with esophageal cancer; therefore, a predictive surrogate marker is needed to assess their effectiveness. CD103+CD8+ tumor-infiltrating lymphocytes, defined as tissue-resident memory T cells (TRM), are promising indicators of response to ICIs, but it remains to be elucidated. This study investigated the association between the efficacy of ICIs and TRM. METHODS: The relationships between TRM infiltrating esophageal cancer, clinicopathological features, and prognosis after nivolumab initiation were examined using immunostaining. Tissue samples were obtained from surgically resected specimens of 37 patients with esophageal cancer who received nivolumab as a secondary or subsequent therapy. In addition, TRM infiltration was compared with programmed death-ligand 1 (PD-L1) expression and blood count parameters as predictors of nivolumab effectiveness. RESULTS: TRM-rich patients had a significant survival benefit after nivolumab initiation (12-months overall survival 70.8% vs 37.2%, p = 0.0485; 12-months progression-free survival 31.2% vs 0%, p = 0.0153) and experienced immune-related adverse events more frequently than TRM-poor patients (6 vs 2 patients). TRM infiltration was weakly correlated with PD-L1 positivity (r = 0.374, p = 0.022), but TRM may indicate more sensitive response to ICIs than PD-L1 expression in this study. Some blood test parameters also weakly correlated with TRM but did not impact prognosis. CONCLUSIONS: TRM-rich patients have a favorable prognosis after nivolumab initiation. Our results suggest that TRM are vital for antitumor immunity and are a promising predictor of ICIs effectiveness.

Prognostic values of tissue-resident CD8+T cells in human hepatocellular carcinoma and intrahepatic cholangiocarcinoma.

BACKGROUND: Tissue-resident CD8+T cells (CD103+CD8+T cells) are the essential effector cell population of anti-tumor immune response in tissue regional immunity. And we have reported that IL-33 can promote the proliferation and effector function of tissue-resident CD103+CD8+T cells. As of now, the immunolocalization and the prognostic values of tissue-resident CD8+T cells in human hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) still remain to be illustrated. METHODS: In our present study, we used the tissue microarrays of HCC and ICC, the multicolor immunohistochemistry (mIHC), and imaging analysis to characterize the tissue-resident CD8+T cells in HCC and ICC tissues. The prognostic values and clinical associations were also analyzed. We also studied the biological functions and the cell-cell communication between tumor-infiltrating CD103+CD8+T cells and other cell types in HCC and ICC based on the published single-cell RNA sequencing (scRNA-seq) data. RESULTS: Our work unveiled the expressions of CD8 and CD103 and immunolocalization of tissue-resident CD8+T cells in human HCC and ICC. Elevated CD8+T cells indicated a better overall survival (OS) rate, implying that tumor-infiltrating CD8+T cells in HCC and ICC could serve as an independent prognostic factor. Moreover, the number of CD103+CD8+T cells was increased in HCC and ICC tissues compared with adjacent normal tissues. HCC patients defined as CD8highCD103high had a better OS, and the CD8lowCD103low group tended to have a poorer prognosis in ICC. Evaluation of the CD103+CD8+T-cell ratio in CD8+T cells could also be a prognostic predictor for HCC and ICC patients. A higher ratio of CD103+CD8+T cells over total CD8+T cells in HCC tissues was negatively and significantly associated with the advanced pathological stage. The percentage of higher numbers of CD103+CD8+T cells in ICC tissues was negatively and significantly associated with the advanced pathological stage. In contrast, the higher ratio of CD103+CD8+T cells over total CD8+T cells in ICC tissues was negatively and significantly associated with the advanced pathological stage. In addition, single-cell transcriptomics revealed that CD103+CD8+T cells were enriched in genes associated with T-cell activation, proliferation, cytokine function, and T-cell exhaustion. CONCLUSION: The CD103+ tumor-specific T cells signified an important prognostic marker with improved OS, and the evaluation of the tissue-resident CD103+CD8+T cells might be helpful in assessing the on-treatment response of liver cancer.

Immunological characteristics of CD103+CD8+ Tc cells in the liver of C57BL/6 mouse infected with plasmodium NSM.

CD103 is an important marker of tissue-resident memory T cells (TRM) which play important roles in fighting against infection. However, the immunological characteristics of CD103+ T cells are not thoroughly elucidated in the liver of mouse infected with Plasmodium. Six- to eight-week-old C57BL/6 mice were infected with Plasmodium yoelii nigeriensis NSM. Mice were sacrificed on 12-16 days after infection and the livers were picked out. Sections of the livers were stained, and serum aspartate aminotransferase (AST) and alanine transaminase (ALT) levels were measured. Moreover, lymphocytes in the liver were isolated, and the expression of CD103 was determined by using qPCR. The percentage of CD103 on different immune cell populations was dynamically observed by using flow cytometry (FCM). In addition, the phenotype and cytokine production characteristics of CD103+CD8+ Tc cell were analyzed by using flow cytometry, respectively. Erythrocyte stage plasmodium infection could result in severe hepatic damage, a widespread inflammatory response and the decrease of CD103 expression on hepatic immune cells. Only CD8+ Tc and γδT cells expressed higher levels of CD103 in the uninfected state.CD103 expression in CD8+ Tc cells significantly decreased after infection. Compared to that of CD103- CD8+ Tc cells, CD103+ CD8+ Tc cells from the infected mice expressed lower level of CD69, higher level of CD62L, and secreted more IL-4, IL-10, IL-17, and secreted less IFN-γ. CD103+CD8+ Tc cells might mediate the hepatic immune response by secreting IL-4, IL-10, and IL-17 except IFN-γ in the mice infected with the erythrocytic phase plasmodium, which could be involved in the pathogenesis of severe liver damage resulted from the erythrocytic phase plasmodium yoelii nigeriensis NSM infection.

Blocking CD47 promotes antitumour immunity through CD103+ dendritic cell-NK cell axis in murine hepatocellular carcinoma model.

BACKGROUND & AIMS: The CD47-signal regulatory protein α (SIRPα) axis inhibits dendritic cell (DC) phagocytosis and contributes to immune evasion. However, the behaviour of DCs and the potential crosstalk between DCs and natural killer (NK) cells in the hepatocellular carcinoma (HCC) microenvironment after CD47 blockade remain unclear. METHODS: The infiltration of CD103+ DCs and NK cells were analysed by immunohistochemistry and immunofluorescence in both human and murine HCC specimens. An orthotopic liver tumour model was used to evaluate the function of the CD103+ DC-NK cell axis after CD47 blockade in vivo in wild-type, Rag1-/-, Batf3-/-, and STING1-/- mice. Phagocytosis assays were performed in CD103+ DC and HCC cell lines. CD103+ DC-derived cytokines were analysed by chemokine array. Spleen-derived NK cells in C57BL/6J mice were used to evaluate cytotoxic functions in vitro. RESULTS: Higher CD47 expression was associated with worse prognosis in patients with HCC. CD47 blockade enhanced antitumour efficacy by stimulating the CD103+ DC-NK cell axis. The hypoxic microenvironment promoted CD47 blockade-induced tumour DNA phagocytosis by CD103+ DCs. By releasing IL-12 and CXCL9, activated CD103+ DCs induced the recruitment of NK cells with upregulated expression of granzyme B, NKG2D, interferon-γ, and tumour necrosis factor-α and downregulated expression of NKG2A. The antitumour effects of CD47 blockade could be abolished by cyclic GMP-AMP synthase (cGAS)-STING pathway inhibition. CONCLUSIONS: In addition to the classical DC-T cell axis, CD47 blockade significantly enhanced the ability of CD103+ DCs to take up tumour DNA, resulting in the stimulation of the cGAS-STING pathway, which promoted the infiltration and activation of NK cells in liver cancer. LAY SUMMARY: Hypoxia (low oxygen levels) is prevalent in the hepatocellular carcinoma microenvironment and promotes the phagocytosis (ingestion and elimination) of tumour DNA by CD103+ dendritic cells (a type of immune cell). Blockade of the cell surface protein CD47 resulted in activation of CD103+ dendritic cells which led to the recruitment and activation of natural killer cells (a different immune cell). When activated, these cells exhibit an antitumour effect.