Autophagy Protects against Colitis by the Maintenance of Normal Gut Microflora and Secretion of Mucus.

Genome-wide association studies of inflammatory bowel diseases identified susceptible loci containing an autophagy-related gene. However, the role of autophagy in the colon, a major affected area in inflammatory bowel diseases, is not clear. Here, we show that colonic epithelial cell-specific autophagy-related gene 7 (Atg7) conditional knock-out (cKO) mice showed exacerbation of experimental colitis with more abundant bacterial invasion into the colonic epithelium. Quantitative PCR analysis revealed that cKO mice had abnormal microflora with an increase of some genera. Consistently, expression of antimicrobial or antiparasitic peptides such as angiogenin-4, Relmß, intelectin-1, and intelectin-2 as well as that of their inducer cytokines was significantly reduced in the cKO mice. Furthermore, secretion of colonic mucins that function as a mucosal barrier against bacterial invasion was also significantly diminished in cKO mice. Taken together, our results indicate that autophagy in colonic epithelial cells protects against colitis by the maintenance of normal gut microflora and secretion of mucus.

Novel anti-carbohydrate antibodies reveal the cooperative function of sulfated N- and O-glycans in lymphocyte homing.

Cell surface glycans play pivotal roles in immune cell trafficking and immunity. Here we present an efficient method for generating anti-carbohydrate monoclonal antibodies (mAbs) using gene-targeted mice and describe critical glycans in lymphocyte homing. We immunized sulfotransferase GlcNAc6ST-1 and GlcNAc6ST-2 doubly deficient mice with sulfotransferase-overexpressing Chinese hamster ovary cells and generated two mAbs, termed S1 and S2. Both S1 and S2 bound high endothelial venules (HEVs) in the lymphoid organs of humans and wild-type mice, but not in those of doubly deficient mice. Glycan array analysis indicated that both S1 and S2 specifically bound 6-sulfo sialyl Lewis X and its defucosylated structure. Interestingly, S2 inhibited lymphocyte homing to peripheral lymph nodes by 95%, whereas S1 inhibited it by only 25%. S2 also significantly inhibited contact hypersensitivity responses and L-selectin-dependent leukocyte adhesion to HEVs. Immunohistochemical and Western blot analyses indicated that S1 preferentially bound sulfated O-glycans, whereas S2 bound both sulfated N- and O-glycans in HEVs. Furthermore, S2 strongly inhibited the N-glycan-dependent residual lymphocyte homing in mutant mice lacking sulfated O-glycans, indicating the importance of both sulfated N- and O-glycans in lymphocyte homing. Thus, the two mAbs generated by a novel method revealed the cooperative function of sulfated N- and O-glycans in lymphocyte homing and immune surveillance.