Functional characteristics of the gene promoters of anti-inflammatory cytokines TGF-b and IL-10 in B lymphocyte cell models

Abstract

B cells play a crucial role in the pathogenesis of various diseases, such as autoimmune disorders, cancers, and infections. Unlike regulatory T cells, the anti-inflammatory capabilities of B cells have only recently garnered attention. Cytokines IL-10 and TGF-β are among the key secreted immunosuppressive factors, therefore studying the characteristics of their transcriptional regulation in B cells appears to be a relevant task. This study focuses on characterizing the promoter regions of IL10 and TGFB1 genes in immortalized B cell lines representing different developmental stages – Reh and Raji. To achieve this, we identified potential promoter regions guided by the epigenetic features of functional regulatory regions determined by bioinformatics methods of ChIP-Seq data analysis of chromatin marks in CD19+ lymphocytes. We examined the activity of selected promoters using reporter analysis in B cells. Additionally, we studied the impact of a single nucleotide polymorphism rs1800469 in the TGFB1 promoter, which is associated with the development of colorectal cancer, chronic obstructive pulmonary disease, and the risk of radiation fibrosis. Our results showed increased promoter activity of IL10 and TGFB1 in the Reh pro-B cells compared to the Raji mature B cells upon stimulation. Interestingly, the presence of the minor allele of rs1800469 led to enhanced TGFB1 promoter activity in the Reh cells. Higher activity of IL10 and TGFB1 promoters in acute lymphoblastic leukemia Reh cells may be associated with the increased immunosuppression, which is characteristic of this pathology. It is also possible that activation of pro-B cells Reh induces their differentiation into monocyte-like cells, which can be polarized into alternatively activated (M2) macrophages by autocrine TGF-β and IL-10. M2 macrophages can function as tumor-associated macrophages and contribute to the development of colorectal cancer. Moreover, increased levels of TGF-β in tissues increase the risks of fibrosis and decrease inflammation levels in chronic obstructive pulmonary disease.