INTESTINAL INFLAMMATION DICTATES GALECTIN- 1-INDUCED APOPTOSIS OF EPITHELIAL CELLS

MUGLIA, CECILIA I; PAPA GOBBI, RODRIGO; SMALDINI PAOLA L; ORSINI DELGADO, LUCÍA; ZANUZZI, CAROLINA; SAMBUELLI, ALICIA; ROCCA, A; TOSCANO, MARTA A; RABINOVICH, GABRIEL; DOCENA, GUILLERMO H

Congreso; Congreso de la Sociedad Argentina de Inmunología (SAI). LXII Reunión científica anual. 2014; 2014

Sociedad Argentina de Inmunologia

Intestinal epithelial cells (IEC) are key players in mucosal homeostasis.When the epithelial barrier is impaired inflammatorydisorders may arise, such as in IBD and allergy. Based on ourprevious findings on the role of Gal-1 in IEC apoptosis, we studiedthe influence of pro-inflammatory cytokines on the pro-apoptoticeffect of this β-galactoside binding protein. IEC were isolated formBalb/c mice and incubated with different pro-inflammatory cytokines(IL-1β, IFN-γ, TNF-α, IL-5 and IL-13). Gal-1 binding and apoptosiswere evaluated by flow cytometry using biotinylated Gal-1, annexinV/propidium iodide and JC1. To investigate the in vivo effectof an inflammatory Th1 or Th2 environment we performed theseassays in IEC isolated from a TNBS-induced colitis and a choleratoxin-driven allergy model. Finally, we assessed Gal-1 binding andGal-1-induced apoptosis by TUNEL (confocal microscopy) in IEC ofIBD patients. We found increased binding of Gal-1 to IEC incubatedwith IL-1β, TNF-α or IL-13 (35±4; 55±13 and 76±8 compared to 9±2of controls, p<0.01), which promoted higher frequency of apoptoticcells compared to cells incubated with Gal-1 in the absence of proinflammatorycytokines (19±8 vs 4±2% annexin V+ cells, p<0.05).Similarly, enterocytes from the colitis model and the food allergymodel showed higher binding of Gal-1 (p<0.05 in both cases) comparedto cells isolated from control mice. Accordingly, we observedhigher percentages of annexin V+IP- cells in IEC isolated fromcolitis or allergic mice compared to controls (p<0.05 and P<0.01,respectively). Moreover, IECs from inflamed areas of IBD showedhigher binding and higher frequency of TUNEL+ cells, compared tonon-inflamed tissues of the same patient or from control patients(p<0.05). Our results provide evidence of the pro-apoptotic roleof Gal-1 in IEC survival, which may impact on integrity of the gutbarrier and the influence of a pro-inflammatory microenvironmentin the immunoregulatory activity of this lectin.