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Annexin A1 pathways triggered in the inflammatory bowel disease treated with infliximab

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Marina de Paula Silva
Total Authors: 1
Document type: Doctoral Thesis
Press: São Paulo.
Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
Defense date:
Examining board members:
Sandra Helena Poliselli Farsky; Patricia Castelucci
Advisor: Sandra Helena Poliselli Farsky

Inflammatory bowel diseases (IBDs) are chronic debilitating illnesses triggered by severe inflammation of the gastrointestinal tract. The tumor necrosis factor alpha (TNF-α) is pointed out as a primordial mediator of IBD pathogenesis; thus, inactivating tools targeting this cytokine have been widely used to treat these diseases. Although IFX is very efficient in inducing/maintaining remission in patients with IBD, side effects and unresponsiveness are still reported, emerging the need for the identification of biomarkers linked to therapeutical efficacy. In the Crohns disease (CD), systemic and tissue expressions of the anti-inflammatory protein, annexin A1 (AnxA1), are increased after IFX treatment and correlate with life quality improvement according to previous reports. AnxA1 and its N-terminal peptide, Ac2-26, act via formyl peptide receptors (FPRs); therefore, the present investigation aimed to understand how FPRs and AnxA1 participate in IFX mechanisms. In the experimental colitis model induced by dextran sulphate sodium (DSS) in wild-type (WT) and AnxA1-deficient mice (AnxA1-/-), IFX attenuated the clinical manifestations only in the WT group. FPRs blockade using the antagonist, Boc-2, impaired IFX effects in WT mice, while AnxA1 absence completely abrogated its efficacy. Furthermore, the inflammatory response was exacerbated after IFX in AnxA1-/- mice, with reduced T regulatory cells, increased tissue MMP9, large intestine shortening, lack of histological remission and 50% mortality. In WT mice, FPR blockade reverted the clinical recovery and mucosal crypts regeneration, with b-actina and brush border disorganization. Using the intestinal epithelial cell line Caco-2 stimulated with TNF-α in vitro, we confirmed that IFX protective effects on tight junctions are lost after FPR1 and FPR2 blockade, compromising the barrier integrity. In the colonic tissue, the expression and secretion of AnxA1 were induced by IFX after colitis. This secretion was shown to be dose-dependent in cells from the intestinal lamina propria treated ex vivo, demonstrating that secreted AnxA1 could constitute one of the resolutive mechanisms of that therapy. In humans with CD, IFX did not modify the expressions of FPR1 and FPR2 in circulating leukocytes or the plasma AnxA1 levels, not differentiating patients responsive or not. However, tissue AnxA1 expression was augmented in responsive patients, and AnxA1/FPR1 levels were negatively correlated with histological remission. Finally, bioinformatic analyses revealed differential expression of FPR1, FPR2 and AnxA1 mRNAs in the colon among remittent or refractory patients even before the beginning of infusions, which was not observed for samples of blood PBCM. In conclusion, we suggest that inducing tissue AnxA1 might be one of the resolution mechanisms of IFX, which is complemented by the activation of FPRs. Moreover, these markers could present predictive value of IFX efficacy, contributing to reaching an early and more permanent remission in IBD. (AU)

FAPESP's process: 16/19682-2 - Annexin A1 pathways triggered in the inflammatory bowel disease treated with infliximab
Grantee:Marina de Paula Silva
Support Opportunities: Scholarships in Brazil - Doctorate