Gracilaria fisheri oligosaccharides ameliorate inflammation and colonic epithelial barrier dysfunction in mice with acetic acid-induced colitis

Objective:To investigate the effect of Gracilaria fisheri oligosaccharides(GFO)on inflammation and colonic epithelial barrier dysfunction in colitis mice.Methods:The animals were treated by oral gavage with distilled water,1000 mg/kg inulin,100,500,or 1000 mg/kg GFO for 14 d,or treated with 50 mg/kg mesalamine for 5 d after colitis induction(on day 10).Histopathology,inflammatory cytokines,colonic permeability,and tight junction proteins were investigated by hematoxylin and eosin staining,immunohistochemical staining,Ussing chamber technique,and Western blotting assays,respectively.Results:GFO ameliorated histological damage in colitis mice when compared to untreated colitis mice.Treatments with 100,500,and 1000 mg/kg GFO reduced TNF-αexpression,while IL-1βwas significantly reduced in colitis mice treated with 500 and 1000 mg/kg.Compared to untreated colitis mice,GFO increased transepithelial electrical resistance,reduced fluorescein isothiocyanate-dextran paracellular flux,and modulated tight junction proteins(occludin and claudin 2)in colitis mice.Conclusions:GFO has anti-inflammatory activity and could modulate colonic epithelial barrier dysfunction in acetic acid-induced colitis mice.Furthermore,GFO could modulate the expression of tight junction proteins that play important roles in colonic barrier function.