CXCR6 defines therapeutic subtypes of CD4+ cytotoxic T cell lineage for adoptive cell transfer therapy in pediatric B cell acute lymphoblastic leukemia.

The potential of cytotoxic CD4+ T cells and tissue resident memory T cells (Trm) in achieving adult leukemia remission have been highlighted [1,2]. We hypothesized that CXCR6 could serve as a marker for cytotoxic CD4+ Trm cells in the bone marrow (BM) of pediatric B-ALL patients. Flow cytometry (FCM) and published single cell RNA sequencing (scRNA-seq) datasets were employed to characterize CXCR6+CD4+ T cells in the BM and peripheral blood (PB) of pediatric B-ALL patients and healthy donors. FCM, scRNA-seq and co-culture were utilized to explore the cytotoxicity of CXCR6+CD4+ T cells in vitro based on in vitro induction of CXCR6+CD4+ T cells using tumor antigens and peripheral blood mononuclear cells (PBMCs). The ssGSEA based on the cell markers identified according to the in vivo scRNA-seq data, the TARGET-ALL-P2 datasets, and integrated machine learning algorithm were employed to figure out the key cells with prognostic values, followed by simulation of adoptive cell transfer therapy (ACT). Integrated machine learning identified the high-risk cells for disease free survival, and overall survival, while simulation of ACT therapy using CXCR6+CD4+T cells indicated that CXCR6+CD4+ T cells could remodel the bone marrow microenvironments towards anti-tumor. Based on the expression of genes involved in formation of resident memory T cells, CXCR6 is not a marker of resident memory CD4+T cells but defines therapeutic subtypes of CD4+ cytotoxic T cell lineage for pediatric B-ALL.

Elevated enteric putrescine suppresses differentiation of intestinal germinal center B cells.

The dysregulation of B cell maturation and putrescine metabolism has been implicated in various diseases. However, the causal relationship between them and the underlying mechanisms remain unclear. In this study, we investigated the impact of exogenous putrescine on B cell differentiation in the intestinal microenvironment. Our results demonstrated that administration of exogenous putrescine significantly impaired the proportion of germinal center B (GC B) cells in Peyer's patches (PPs) and lamina propria. Through integration of bulk RNA sequencing and single-cell RNA sequencing (scRNA-seq), we identified putrescine-mediated changes in gene drivers, including those involved in the B cell receptor (BCR) signaling pathway and fatty acid oxidation. Furthermore, putrescine drinking disrupted T-B cell interactions and increased reactive oxygen species (ROS) production in B cells. In vitro activation of B cells confirmed the direct suppression of putrescine on GC B cells differentiation and ROS production. Additionally, we explored the Pearson correlations between putrescine biosynthesis activity and B cell infiltration in pan-cancers, revealing negative correlations in colon adenocarcinoma, stomach adenocarcinoma, and lung adenocarcinoma, but positive correlations in liver hepatocellular carcinoma, and breast invasive carcinoma. Our findings provided novel insights into the suppressive effects of elevated enteric putrescine on intestinal B cells differentiation and highlighted the complex and distinctive immunoregulatory role of putrescine in different microenvironments. These findings expand our understanding of the role of polyamines in B cell immunometabolism and related diseases.