The pro-apoptotic galectin-1 is functionally inhibited in inflamed intestinal areas of IBD patients

PAPA GOBBI R; ROCA A; SAMBUELLI A; RAVINOVICH G; TOSCANO M; GIL A; NEGREIRA S; HUERNOS; GONCALVES; BELLICOSO; TIRADO; CURCIARELLO R; YRIGOYEN; MUGLIA; YANTORNO M; DOCENA G

Copenhagen

Congreso; ECCO 2014; 2014

European Crohn's and Colitis Organisation

Background: Inflammatory bowel diseases (IBD) are multifactorialdisorders characterized by a chronic and relapsingintestinal inflammation. Galectin-1, a ubiquitous endogenouslectin, has been implicated in several chronic inflammatorydisorders. We aimed to analyze its role in the colonic mucosa ofpatients with Crohn?s disease (CD) and Ulcerative colitis (UC).Methods: Gal-1 expression was studied by qPCR, immunoblottingand histology in biopsies and resected tissues of patientswith IBD (n = 26) and control patients (n = 20). Gal-1-specificbinding ligands were also analyzed by flow cytometry in laminapropria and its physiologycal role in the induction of cell deathwas evaluated by flow cytometry.Results: We found in 21 biopsies of CD and 22 biopsiesof CU that Gal-1 mRNA expression was increased in colonicinflamed areas (p < 0.01). However Gal-1 protein expressionwas lower as compared to non-inflamed areas. To clarifythis controversial finding we cultured control biopsies withTNF-a (1, 5 and 10 ng/mL) and observed a dose-responseincrease in the expression and secretion of Gal-1 (p < 0.05).Additionally, fibroblast supernatants from IBD patients show theability to cleave Gal-1 protein. Both findings could explain thedissociation between mRNA expression and protein secretion.Gal-1-specific binding sites were considerably reduced inisolated lamina propria CD4 or CD8 lymphocytes from inflamedareas (n = 11), as compared to non-inflamed areas (n = 10) orcontrol samples (n = 8) (p < 0.05). A consistent lower bindingof PNA and C2GnT-1 expression was found in IBD samples,suggesting lower levels of asialo-core 1-O-glycans. Whenapoptosis was analyzed we found that 10 ng Gal-1 increased thefrequency of annexin-1-positive cells in control patients (n = 6)(17.94% with medium and 32.94% with 10 ng Gal-1. p < 0.05).Nevertheless no increased in the frequency of annexin-1-positive cells was observed in inflamed areas of IBD patients(n = 5, p = 0.9647).Conclusions: In conclusion, we found a differential expressionof Gal-1 and Gal-1-specific glycosylated ligands in biologicalsamples of IBD. We also found that Gal-1 exerts a pro-apoptoticeffect in T lymphocytes from non-inflamed areas, whereasT cells from inflamed areas are refractory to cell death. Thereduced expression of this protein in inflamed areas and theabsence of Gal-1-specific sites may have relevant implicationsin the survival vs cell death of mucosal T lymphocytes. Thismight impact in the persistency of the inflammatory process inthe affected colon.