Effects Of Black Rice Extracts On Allergenicity Related To Celiac Disease Of Gliadin

Objective: Celiac disease is an autoimmune disorder elicited in genetically predisposed individuals by the ingestion of gluten.Gluten proteins,especially gliadin,activate the immune responses,resulting intestinal inflammation and tissue damage.At present,the only treatment for celiac disease is a strictly gluten-free diet for life.However,gluten protein is widely used in food processing,so it is difficult to completely avoid the intake of gluten in daily life for celiac patients.Black Rice has anti-oxidation and anti-inflammation function,which maybe alleviate gluten-induced oxidative stress and inflammation,and reduce intestinal injury.Therefore,we aim to investigate the effects of black rice extracts on allergenicity related to celiac disease of gliadin,so as to provide new strategies for alternative therapies of celiac disease.Methods: Caco-2 cells were incubated with 1.5 mg/mL pepsin–trypsin-digested gliadin(PT-gliadin)for 24 h,in order to induce oxidative stress and inflammatory responses.Caco-2 cells were treated with different concentrations of black rice extract(50 ?g/mL,100 ?g/mL,200 ?g/mL)for 3 h respectively,then incubated with PT-gliadin(1.5 mg/mL for 24 h),then detected cell viability,reactive oxygen species(ROS),reduced glutathione(GSH),malondialdehyde(MDA)level and superoxide dismutase(SOD)activity,the level of associated inflammatory factor IL-6?IL-8 and detected transglutaminase II(TG2)and tight junction protein Occludin expression by Western blotting.Gliadin-sensitized BALB/c mice model was established,and black rice extract(200 mg/kg,400mg/kg,800mg/kg)was administered via gavage daily for 28 days.Then the level of specific antibody IgG?IgA in serum,the level of relevant cytokine IL-1??TNF-??IFN-??IL-4?IL-6?IL-10?IL-13?IL-15?IL-17A?IL-21 in serum,spleen cell supernatant and jejunal lysate were detected,and intestinal histomorphology(duodenum,jejunum and ileum)was analyzed.Results: Gliadin inhibited the activity of Caco-2 cells,increased the level of ROS and MDA,decreased the level of GSH and the activity of SOD(P<0.05),and promoted the secretion of IL-6 and IL-8 in Caco-2 cells,down-regulated the expression of tight junction protein Occludin and up-regulate the expression of TG2 Protein(P<0.05),indicating the successful establishment of gliadin-induced oxidative stress and inflammatory cell responses.Black Rice extract reduced gliadin-induced toxicity to the proliferation of Caco-2 cells,eliminated the excessive accumulation of ROS induced by gliadin,inhibited lipid oxidation and increased the SOD activity and GSH content(P<0.05);also inhibited gliadin-induced secretion of IL-6,IL-8 and the expression of TG2 protein in Caco-2 cells,up-regulated the expression of tight junction protein Occludin in a dose-dependent manner(P<0.05).Gliadin significantly increased the levels of IgG and IgA in serum of gliadin-sensitized BALB/c mice(P<0.05),and the levels of IL-6,TNF-?,IL-17 A,IL-21,IL-4,IL-10 and IFN-? in serum and supernatant of spleen cells(P<0.05);The levels of IL-4,IL-1,IFN-?,IL-15 in jejunal lysate were increased(P<0.05),however the levels of IL-17 A,TNF-?,IL-10 and IL-21 in Jejunal lysate were decreased(P<0.05);Gliadin resulted in changes of intestinal histomorphology,villous atrophy,partial edema and crypt hyperplasia,indicating the successful establishment of gliadin-sensitized BALB/c mice model.Black Rice extract increased further the level of IgG and IgA,regulated the levels of IL-1,TNF-?,IFN-?,IL-4,IL-6,IL-10,IL-13,IL-15,Il-17 A,IL-21 in serum,supernatant of spleen cells and jejunal lysate of gliadin-sensitized mice,reduced the inflammation induced by gliadin and obviously improved intestinal injury induced by gliadin.Conclusion: Black Rice extract obviously alleviated the oxidative damage and inflammatory reaction induced by gliadin,improved the cell tight junction,improved intestinal injury induced by gliadin,indicating that black rice extract can alleviate the allergenicity related to celiac disease of gliadin to some extent.