Novel insights into the regulation of CCR7 receptor expression in immune cells

点击翻译按钮获取中文摘要

Toll-like receptors (TLR) recognize microbial molecules, which results in the development of inflammatory reactions caused by the activation of the NF-kB regulating expression of cytokines and chemokines. Pathogen-led TLR activation provides rapid recruitment of inflammatory cells to the site of infection and activates them to induce an arsenal of antimicrobial functions. Until recently, only innate immune cells, such as macrophages and DCs, and epithelial cells lining mucosal surfaces were known to express functionally competent TLRs. However, many studies have now reported physiologically relevant signal-competent TLRs in lymphocytes. Chemokines CCL19 and CCL21, the natural ligands of CCR7 are important for immune cell migration to lymph nodes. Since TLR activation and inflammation are hallmarks of viral and bacterial infections, it is of vital importance to determine whether they can regulate CCR7-dependent migration in order to better understand factors leading to T cell dissemination. In this research program, we seek to gain novel insights into the molecular and cellular events leading to CCR7 expression following TLR activation in T cells. Based on our exciting preliminary results, the following specific aims are proposed in this five-years research program: AIM 1. To establish whether TLR activation modulate CCR7 expression and functionality in T cells. In this objective, we will monitor CCR7 mRNA induction following TLR activation and inflammation of T cells by real-time RT-PCR. FACS analysis using a specific antibody against CCR7 will confirm the expression of CCR7 at cell surface. The functionality of the receptors will be verified by chemotaxis assays. AIM 2. To determine transcription factors and signaling modules elicited in T cells activated by TLR agonists that lead to the modulation of CCR7 expression. We propose to elucidate signaling events and transcription factors essential for the TLR-induced expression of CCR7. First, we will study the promoter activity using molecular constructs containing the full-length or deleted versions of the promoter region of CCR7. Next using electrophoretic mobility shift and chromatin immunoprecipitation assays, we will explore the transcription factors as well as the signaling events required for CCR7 expression in TLR-stimulated T cells. AIM 3. To determine whether the observed modulation in CCR7 expression in T cells affects migration in a mouse model. Mice that have an humanized immune system represent a suitable animal model to gain important insights in the comprehension of the immune system. Here, we will use such model to study the physiological relevance of our hypothesis. This innovative research program will give for the first time, novel insights into the comprehension of T cell migration in response to infections in response to CCL19 and CCL21, two CCR7 natural ligands.