title: Specific-sized hyaluronan fragments promote expression of human β-defensin 2 in intestinal epithelium.
abstract: Hyaluronan (HA) is a glycosaminoglycan polymer found in the extracellular matrix of virtually all mammalian tissues. Recent work has suggested a role for small, fragmented HA polymers in initiating innate defense responses in immune cells, endothelium, and epidermis through interaction with innate molecular pattern recognition receptors, such as TLR4. Despite these advances, little is known regarding the effect of fragmented HA at the intestinal epithelium, where numerous pattern recognition receptors act as sentinels of an innate defense response that maintains epithelial barrier integrity in the presence of abundant and diverse microbial challenges. Here we report that HA fragments promote expression of the innate antimicrobial peptide human β-defensin 2 (HβD2) in intestinal epithelial cells. Treatment of HT-29 colonic epithelial cells with HA fragment preparations resulted in time- and dose-dependent up-regulated expression of HβD2 protein in a fragment size-specific manner, with 35-kDa HA fragment preparations emerging as the most potent inducers of intracellular HβD2. Furthermore, oral administration of specific-sized HA fragments promotes the expression of an HβD2 ortholog in the colonic epithelium of both wild-type and CD44-deficient mice but not in TLR4-deficient mice. Together, our observations suggest that a highly size-specific, TLR4-dependent, innate defense response to fragmented HA contributes to intestinal epithelium barrier defense through the induction of intracellular HβD2 protein.
authors: Department of Molecular Medicine, Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
authors: David R
authors: DR
authors: Hill
authors: Sean P
authors: SP
authors: Kessler
authors: Hyunjin K
authors: HK
authors: Rho
authors: Mary K
authors: MK
authors: Cowman
authors: Carol A
authors: CA
authors: de la Motte
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003106:Colon / Q000276:immunology / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000235:genetics / Q000276:immunology; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006820:Hyaluronic Acid / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D007113:Immunity, Innate / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008817:Mice, Mutant Strains; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D023083:beta-Defensins / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology
chemical_list: C497483:CD44 protein, human; C476399:Cd44 protein, mouse; C106641:DEFB4A protein, human; C117047:Defb2 protein, mouse; D018960:Hyaluronan Receptors; C495345:TLR4 protein, human; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D023083:beta-Defensins; D006820:Hyaluronic Acid