Trauma induces expansion and activation of a memory-like Treg population

Tumor derived exosomal ENTPD2 impair CD8+ T cell function in colon cancer through ATP-adenosine metabolism reprogramming

BACKGROUND

Extracellular ATP-AMP-adenosine metabolism plays a pivotal role in modulating tumor immune responses. Previous studies have shown that the conversion of ATP to AMP is primarily catalysed by Ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1/CD39), a widely studied ATPase, which is expressed in tumor-associated immune cells. However, the function of ATPases derived from tumor cells themselves remains poorly understood. The purpose of this study was to investigate the role of colon cancer cell-derived ATPases in the development and progression of colon cancer.

METHODS

Bioinformatic and tissue microarray analyses were performed to investigate the expression of ATPase family members in colon cancer. An ATP hydrolysis assay, high-performance liquid chromatography (HPLC), and CCK8 and colony formation assays were used to determine the effects of ENTPD2 on the biological functions of colon cancer cells. Flow cytometric and RNA-seq analyses were used to explore the function of CD8+ T cells. Immunoelectron microscopy and western blotting were used to evaluate the expression of ENTPD2 in exosomes. Double-labelling immunofluorescence and western blotting were used to examine the expression of ENTPD2 in serum exosomes and colon cancer tissues.

RESULTS

We found that ENTPD2, rather than the well-known ATPase CD39, is highly expressed in cancer cells and is significantly positively associated with poor patient prognosis in patients with colon cancer. The overexpression of ENTPD2 in cancer cells augmented tumor progression in immunocompetent mice by inhibiting the function of CD8+ T cells. Moreover, ENTPD2 is localized primarily within exosomes. On the one hand, exosomal ENTPD2 reduces extracellular ATP levels, thereby inhibiting P2X7R-mediated NFATc1 nuclear transcription; on the other hand, it facilitates the increased conversion of ATP to adenosine, hence promoting adenosine-A2AR pathway activity. In patients with colon cancer, the serum level of exosomal ENTPD2 is positively associated with advanced TNM stage and high tumor invasion depth. Moreover, the level of ENTPD2 in the serum exosomes of colon cancer patients is positively correlated with the ENTPD2 expression level in paired colon cancer tissues, and the ENTPD2 level in both serum exosomes and tissues is significantly negatively correlated with the ENTPD2 expression level in tumor-infiltrating CD8+ T cells.

CONCLUSION

Our study suggests that exosomal ENTPD2, originated from colon cancer cells, contributes to the immunosuppressive microenvironment by promoting ATP-adenosine metabolism. These findings highlight the importance of exosome-derived hydrolytic enzymes as independent entities in shaping the tumor immune microenvironment.

TIGIT-Fc Prolongs Corneal Allograft Survival in Mice by Upregulating TIGIT/CD226 Expression and the Proportion of Helios + Foxp3 + Treg Cells

BACKGROUND

Reduction of graft rejection remains key issue for supporting long-term graft retention after corneal transplantation. The relevance of Treg in reduction of corneal allografts rejection has been demonstrated. It has been recently reported that in addition to Foxp3, Helios is also considered to be a marker of activated Treg. Helios + Foxp3 + Treg are considered to be the true immunosuppressive Treg. TIGIT is an immunosuppressive costimulatory molecule that was found to be highly expressed on the surface of Helios + Foxp3 + Treg.

METHODS

In this study, we aimed to explore whether supplementing TIGIT would result in an expansion and activation of Helios + Foxp3 + Treg thus to mediate an immune tolerance following corneal transplantation by administering topically and systemically TIGIT-Fc treatment in murine models.

RESULTS

TIGIT-Fc treatment significantly improved the survival of corneal allograft compared with the control group. TIGIT-Fc treatment increased TIGIT/CD226 expression, the proportion of Helios + Foxp3 + Treg cells and an enhanced ex vivo suppressive effect from peripheral lymph nodes isolated Treg cells. Furthermore, the expression of Helios in corneal grafts was upregulated, whereas expression of CD226 and production of aqueous interferon-γ and VEGF were reduced by TIGIT-Fc treatment.

CONCLUSIONS

TIGIT-Fc treatment could specifically upregulate Helios + Foxp3 + Treg-mediated immune response after allogeneic corneal transplantation via TIGIT/CD226-CD155 pathway which improves the survival of allografts.

Neutrophil phenotypes implicated in the pathophysiology of post-traumatic sepsis

BACKGROUND

The disruption of immune homeostasis after trauma is a major cause of post-traumatic organ dysfunction and/or sepsis. Recently, a variety of neutrophil phenotypes with distinct functions have been identified and suggested as involved in various clinical conditions. The association between neutrophil phenotypes and post-traumatic immunodeficiency has also been reported, yet the specific neutrophil phenotypes and their functional significance in post-traumatic sepsis have not been fully clarified. Therefore, we sought to investigate neutrophil phenotypic changes in a murine model, as these may hold prognostic value in post-traumatic sepsis.

MATERIALS AND METHODS

Third-degree burns affecting 25% of the body surface area were used to establish trauma model, and sepsis was induced 24 h later through cecal ligation and puncture (CLP). The Burn/CLP post-traumatic sepsis model and the Sham/CLP control model were established to assess the immunological status after trauma. Histopathological evaluation was performed on the spleen, liver, kidneys, and lung tissues. Immunological evaluation included the assessment of neutrophil markers using mass cytometry as well as cytokine measurements in serum and ascitic fluid through multiplex analysis using LUMINEX®.

RESULTS

The Burn/CLP group had a lower survival rate than the Sham/CLP group. Histopathological examination revealed an impaired immune response and more advanced organ damage in the Burn/CLP group. Furthermore, the Burn/CLP group exhibited higher levels of transforming growth factor-beta 1 in the blood and generally lower levels of cytokines than the Sham/CLP group. CD11b, which is involved in neutrophil adhesion and migration, was highly expressed on neutrophils in the Burn/CLP group. The expression of CD172a, which is related to the inhibition of phagocytosis, was also upregulated on neutrophils in the Burn/CLP group. The expression of sialic acid-binding lg-like lectin F and CD68 also differed between the two groups.

CONCLUSION

Different neutrophil phenotypes were observed between Burn/CLP and Sham/CLP groups, suggesting that neutrophils are implicated in the immune imbalance following trauma. However, further studies are needed to prove the causal relationships between neutrophil phenotypes and outcomes, including survival rate and organ dysfunction.

Distinct Injury Responsive Regulatory T Cells Identified by Multi-Dimensional Phenotyping

CD4+ regulatory T cells (Tregs) activate and expand in response to different types of injuries, suggesting that they play a critical role in controlling the immune response to tissue and cell damage. This project used multi-dimensional profiling techniques to comprehensively characterize injury responsive Tregs in mice. We show that CD44high Tregs expand in response to injury and were highly suppressive when compared to CD44low Tregs. T cell receptor (TCR) repertoire analysis revealed that the CD44high Treg population undergo TCRαβ clonal expansion as well as increased TCR CDR3 diversity. Bulk RNA sequencing and single-cell RNA sequencing with paired TCR clonotype analysis identified unique differences between CD44high and CD44low Tregs and specific upregulation of genes in Tregs with expanded TCR clonotypes. Gene ontology analysis for molecular function of RNA sequencing data identified chemokine receptors and cell division as the most enriched functional terms in CD44high Tregs versus CD44low Tregs. Mass cytometry (CyTOF) analysis of Tregs from injured and uninjured mice verified protein expression of these genes on CD44high Tregs, with injury-induced increases in Helios, Galectin-3 and PYCARD expression. Taken together, these data indicate that injury triggers the expansion of a highly suppressive CD44high Treg population that is transcriptionally and phenotypically distinct from CD44low Tregs suggesting that they actively participate in controlling immune responses to injury and tissue damage.