Inflammatory bowel diseases (IBDs) identify idiopathic and debilitating illnesses characterized by severe gastrointestinal inflammation. Tumor necrosis factor-alpha (TNF-a) is considered the main cytokine involved in the IBD pathogenesis, thus, inactivating tools addressing this pro-inflammatory cytokine have been developed, including the anti-TNF-a monoclonal antibody, infliximab (IFX). Despite IFX efficacy in patients refractory to previous treatments, there are several reports of side effects as well as of patients who do not respond to this therapy, representing a major burden to patients life quality and high cost in public health expenditures. As such, a current and most important challenge in IBDs management is to identify markers that predict non-responsiveness to therapies. Recent studies have described a possible relationship between the positive response to IFX and expression of endogenous annexin A1 (ANXA1) in both CD patients and mice with experimental colitis. This represents the basis for this application. Mice deficient in ANXA1 do not respond to IFX treatment during an acute model of experimental colitis induced by dextran sulphate sodium (DSS). The mechanisms involved in this phenomenon remain unclear. The biology of ANXA1 dictates that after mobilization, this protein can act via autocrine, paracrine or juxtacrine pathways downstream an interaction with formyl-peptide receptors (FPR). Several anti-inflammatory and homeostatic effects result from the cascades activated by these bindings. The FPR1, 2 and 3 are known as promiscuous receptors because they can be stimulated by a wide range of ligands beyond ANXA1 or its pharmacophore peptide Ac2-26. Relevantly, due to their participation in antimicrobial and inflammatory processes, FPRs have been studied in IBDs. During the PhD project, we demonstrated that FPR1 and 2 signaling pathways are relevant to control experimental colitis manifestation in vivo and the ensuing intestinal epithelial damage. FPR1 and 2 are also involved in IFX efficacy in attenuating DSS-induced colitis in mice during chronification, with FPR1 displaying a prominent role in protecting the epithelial barrier. Besides that, we demonstrated the relevance of ANXA1, one of FPRs ligands, in these contexts. However, there are no further information about FPRs and other ligands involvement in IBDs pathogenesis and in cases of patients refractory to therapies. Here we propose to deepen our knowledge on this subject, asking the scientific question of whether FPRs desensitization could be associated to IFX unresponsiveness. To this end, we would like to apply for a fellowship at the William Harvey Research Institute, Queen Mary University of London, under Dr Mauro Perretti supervision. We propose to study localization and expression of FPRs by flow cytometry on ImageStreamX after different protocols of desensitization and ANXA1 depletion in Caco-2 cells and leukocytes. Associated with other experimental approaches, such as cytokines quantification and calcium mobilization, data obtained may contribute to decipher the pathways triggered by FPR agonists during the resolution of the IBD inflammation paving the way to the development of novel therapeutic strategies and help patients to reach an earlier and more permanent remission.
News published in Agência FAPESP Newsletter about the scholarship: