Effect And Mechanism Of Hydrogen Sulfide On Food Allergy In Mice

Food allergy（FA）is becoming a common public health problem all over the world,but there are still no effective drugs for FA.With the development of science and technology,the pathogenesis of FA has been studied in recent ten years,but it is still necessary to further explore the pathogenesis of FA in order to prevent and treat FA.Intestinal tract is the main area of FA.Intestinal homeostasis and immunoregulation are closely related to FA.Hydrogen sulfide（H₂S）,together with nitric oxide（NO）and carbon monoxide（CO）,plays an important role in many physiological processes.As a new type of gas signaling molecule,H₂S can effectively regulate the inflammatory response,and can also be used as a key target in asthma and other diseases.This study first explored the changes of endogenous H₂S level in ovalbumin（OVA）-induced mouse FA model.Firstly,the level of H₂S in plasma and jejunum was detected by methylene blue spectrophotometry.Then,the enzyme producing H₂S in jejunum,cystathionineβ-synthase（CBS）and cystathionineγ-lyae（CSE）were detected by Western blotting.At the same time,the CSE expressed in jejunum was localized by immunofluorescence.The results showed that the level of H₂S in FA mice was significantly decreased.Immunofluorescence showed that the expression of CSE,an enzyme producing H₂S from intestinal epithelium,was decreased.These results suggest that endogenous H₂S may be involved in the pathological process of FA in mice.Secondly,sodium hydrosulfide hydrate（Na HS）was used to supplement H₂S to further explore the role of H₂S in mouse FA.Then,we further used the H₂S deficient mice(CSE^-/-mice)to verify the effect of H₂S deficient mice on FA.The results showed that the allergic symptoms such as diarrhea,hypothermia and weight loss were alleviated,and the levels of OVA specific immunoglobulin E（OVA-s Ig E）and mouse mast cell protein-1（m MCP-1）in serum were significantly decreased.In addition,the gene expression of IL-4,IL-5 and IL-13in jejunum was significantly decreased by H₂S supplementation.The results of flow cytometry showed that the proportion of Th2（T helper 2）cells in total CD4⁺T cells and the proportion of the group 2 innate lymphoid cell（ILC2）cells in mesenteric lymph node（MLN）were significantly decreased,while the proportion of Treg cells and ILC3 cells were significantly increased.H₂S deficiency significantly increased the incidence of diarrhea,aggravated allergic symptoms such as body temperature and weight loss,and significantly increased the serum levels of OVA-s Ig E and m MCP-1.In addition,the proportion of Th2 cells in total CD4⁺T cells and ILC2 cells in MLN were significantly increased,while the proportion of Treg cells was significantly decreased.Further verification of the role of H₂S by regulating the level of IL-25 in the intestine.The results showed that neutralizing IL-25 in CSE^-/-mice effectively alleviated the allergic symptoms of diarrhea and hypothermia,and significantly reduced the levels of OVA-s Ig E and m MCP-1 in serum,and significantly reduced the gene level of Th2 type cytokines in intestine.Finally,the mechanism of H₂S regulating IL-25 was explored.The results showed that the expression of c-Jun was significantly increased after salicin stimulated intestinal epithelial cells,and the expression of IL-25 was inhibited after c-Jun silencing,suggesting that H₂S may inhibit the expression of IL-25 by regulating c-Jun.This study demonstrated that the level of H₂S and the expression of CSE decreased significantly in FA mice.H₂S may down regulate the expression of Th2 cytokines by regulating c-Jun,inhibiting the expression of IL-25,reducing the level of IL-25 derived from intestinal epithelium,and regulating the changes of immune cells in MLN,thus inhibiting FA induced by OVA in mice.In conclusion,H₂S plays an important role in OVA induced FA in mice,which may be used as a target for the prevention of FA.This experiment can provide a theoretical basis for the development of dietary nutrition related products.