Nuevos mecanismos protectores en la Enfermedad Inflamatoria Intestinal: Sistema Endocannabinoide y Haptoglobina.

Abstract

Inflammatory Bowel Disease (IBD) (Crohn’s disease (CD) and Ulcerative Colitis (CU)), is a chronic, poligenic, complex and relapsing disease of the gastrointestinal tract. _x000D_ Recent studies in vitro and experimental animal models have suggested a protective role of the Endocannabinoid System (ES) and Haptoglobin in IBD. _x000D_ Study 1: Endocannabinoid system and IBD_x000D_ We examined, using Western-Blotting and immunohistochemistry, the expression of all components of ES (receptors - CB1, CB2-, biosynthesis enzymes -DAGL-α/β, NAPE-PLD-, and degradating enzymes -FAAH y MAGL- in healthy human colonic tissue, and in active UC patients, without any previous treatment, and in quiescent phase. _x000D_ We identified for the first time, the presence of all components of ES in normal colonic tissue. As novelties we pointed out the expression of: CB1 in globlet cells; CB2 in Paneth cells and in neuroenteric plexi; FAAH and MAGL in plasmatic cells and in polymorphonuclear cells; byosynthesis enzymes in epithelial cells and in both mienteric plexi. _x000D_ Besides, we evidenced the presence of a basal endocannabinoid tone modified in UC patients, in active flares as in quiescent phases: _x000D_ - In UC patients with mild-moderate flares, there was an increase in CB2 expression, that returned to normality in the quiescent phase. _x000D_ - In the active phase there was a decrease in NAPE-PLD expression, that recovered in the quiescent phase, and an increase in DAGL-α and MAGL expression, that is maintained in the quiescent phase. _x000D_ In conclusion, the ES components are altered during inflammation in UC, mainly by an increase in CB2 expression. Therefore, the development of new drugs raising the endocannabinoid tone during inflammation may lead to new therapeutical approaches in IBD. _x000D_ Study 2: Haptoglobin and IBD. _x000D_ Hp is a protein with immunomodulatory properties. There is a polymorphism in the Hp gene, with two different alleles: Hp1 and Hp2. The goal of this study was to investigate the role of Hp in IBD, both genetically and functionally. _x000D_ We genotyped, using a “touch-down” PCR, 1061 CD patients, 755 UC patients and 452 healthy individuals. Prevalence of Hp2 was higher in CD and UC patients than in controls. These results were confirmed in IBD trios families (464 CD trios and 151 UC trios) where Hp2 allele was over-transmitted to the affected offspring. _x000D_ We determined serum levels of Hp in 62 healthy controls. Serum Hp values were lower in individuals with genotype 22. _x000D_ We developed two murine models of experimental colitis (DSS and OXA) and we demonstrated that Hp KO mice developed more severe colitis. _x000D_ In Hp KO mice, mRNA levels of IL-17, INF-γ, TNF and IL-6 in DSS-colitis and mRNA levels of IL-13 en OXA-colitis were higher than in WT mice. In DSS-colitis, after adding IL-23, in Hp KO mice production of IL-17 was significantly increased._x000D_ To summarized, the Hp polymorphism is implicated in genetic susceptibility to IBD, underscoring common pathogenic pathways with other immune-based diseases. Moreover, Hp has a role in reducing the severity of experimental colitis inflammation and it modulates IL-17 production, suggesting potencial therapeutical applications in IBD.

Date of Award	7 May 2012
Original language	Spanish
Supervisor	Montserrat Andreu Garcia (Director) & Adolfo Díez Pérez (Director)