Functional Genomics of Regulatory T cells - Novel Therapeutic Strategies for Immunomodulation

The main goal of the research plan is to understand how the immune system controls immune reactivity and balances self-tolerance versus an efficient immune defence. This could potentially lead to new understanding of key factors in the pathogenesis of hum an disease. Specifically, we aim to investigate the molecular mechanisms applied by regulatory T (TR) cells, and how TR cells contribute to immune control and immune-related disease. The main goal will be addressed through a series of interrelated subobje ctives: i) Identify key molecular differences between FOXP3 expressing and non-expressing T cells and understand the regulation of FOXP3 by an integrative approach by taking advantage of quantitative proteomics by stable isotope labeling (SILAC and cICAT) combined with microarray expression profiles using Affymetrix genechip analysis. SILAC involves growing one cell population in normal medium and another in medium containing heavy (isotopic) amino acids, making their peptides distinguishable by mass; Ii) New data support that TR cells induced in vitro suppress T cell function through a cAMP-dependent mechanism that involves production and secretion of PGE2. We aim to understand the regulation of COX-2 expression in TR cells in relation to other immunomod ulatory mechanisms and whether up-regulation of COX-2 expression is dependent on FOXP3 transcriptory activity or vice versa; Iii) In vitro reversal of TR cell induced immunosuppression in cell culture experiments by disruptors of cAMP signalling including cAMP antagonists, peptide disruptors of PKA anchoring and COX-2 inhibitors; Iv) Identify to what extent TR cells suppress HIV and tumor-specific immune responses in colorectal cancer (ongoing) and other neoplasms in in vitro experiments and animal models ; V) Develop clinically useful strategies for improving the immune function against malignant tumors, HIV and autoimmune diseases based on molecular insight into the mechanisms of TR cell-induced immune suppression.