Inhibition Of NLRP3/IL-1? Axis By Sulforaphane Through Nrf2 To Reduce Inflammatory Response In Ulcerative Colitis

Background Ulcerative colitis(UC)is an undiscovered cause and mechanism of ulcerative colitis,which mainly involves superficial mucosa of colon and rectum.The clinical manifestation of ulcerative colitis is mucus purulent stool as a characteristic lesion,which is not difficult to distinguish under endoscopy.But it is also recognized as a non-specific inflammatory disease which cannot be cured completely.At present,the pathogenesis of the disease has not been fully clarified,and a large number of literatures have reported that the occurrence of the disease and the abnormal autoimmune function of the body has a strong correlation,because the immune function is too strong,It leads to self-attack and a large number of immune responses.Therefore,in the course of clinical treatment,some scholars should take care of it.Immunosuppressive therapy has achieved good results.In addition,the pathogenesis may also have a close relationship with congenital genetic factors,the release of inflammatory factors and other non-immune pathogeny.It has also been confirmed that the pathogenesis of UC is consistent with oxidative stress factors.Oxidative stress mainly induces the expression and release of oxygen free radicals(Reactive Oxy-gen Species,ROS)through a variety of related mechanisms and mediates the differentiation of a variety of cells.Apoptosis and proliferation,which lead to the injury of colonic mucosa,are important related mechanisms of intestinal inflammation.Inflammation includes promoter,sensation,The mass production of ROS is made up of four parts:mass,medium and target tissue.Through NLRs and other similar intracellular receptor receptors,the damage signals are transmitted to the competent cells to identify the damage signals.And this signal can cause the stimulation of the sensory cells and the production of a large number of inflammatory mediators,leading to the activation of the intracellular receptors of the sensory cells into NLRP3 inflammatory bodies,which in turn mediate the whole body of the body.Local inflammatory reaction.Ros can attack all components of the cell to induce the assembly of NLRP3 inflammatory bodies,and can directly recognize or recruit precursors of Caspase-1 through specific proteins to produce activated Caspase-1.Which in turn promotes the maturation and secretion of interleukin-1 ?(IL-1?)and interleukin-18(IL-18),These inflammatory factors have been proved to be of great significance in inducing inflammatory bowel disease and aggravating its activity.The excessive secretion of inflammatory factors can promote the excessive proliferation and differentiation of CD4 T lymphocytes to produce abnormal immune function,and it can also benefit the abnormal IL-2R of lymphocytes.The over-expression of these factors can result in the mass secretion of inflammatory mediators,and the proliferation and release of these factors can cause a vicious cycle that aggravates the systemic and local inflammatory reactions,when acting on the junction.Rectal mucosa for local mucosal tissue will produce inflammatory damage,mucosal surface appearance of congestion and edema.IL-18 can stimulate Th1 cells to secrete a variety of inflammatory factors through various mechanisms,the most important is IFN-? factor,its activity is much stronger than other inflammatory factors.IL-18 can also enhance the cytotoxicity of NK cells and CD8 T lymphocytes and promote the proliferation of T cells,and can mediate the aggravation of inflammatory response induced by various cytokines and chemokine.The overexpression of proliferative inflammatory mediators can also play a role in mediating programmed focal death.The idea of focal death is a pro-inflammatory death that does not equate to apoptosis in normal cells.The mechanism is that the causative factor mediates the release of a large number of intracellular substances through the lytic cell membrane after the rupture of the cell membrane.The release of content results in a strong inflammatory response.Transcription factor NF-E2-related factor 2(Nrf2)is considered to play a key role in defense against oxidative phosphorylation and toxic mediators.It can protect the existence of enzymes,cytokines and adhesion factors,thus play an important role in the occurrence and development of various inflammatory diseases,which is also an indispensable regulatory factor to resist oxidative stress.Under normal conditions,Nrf2 can combine with desired binding proteins,which appear to be weak and fast when they are affected by oxidative stress or other damage factors in the body.Decomposition and dissociation,and the formation of heterodimers in the nucleus in a stable state,induced activation to produce a eries of antagonistic oxidation effects.Sulforaphane(sulforaphane,SFN),also known as sulforaphane,has been proved to be a natural dietary acidic substance rich in Cruciferae,which can induce the activation of detoxifying enzymes to produce anticancer substances and regulate the immunity of the human body to play an anti-cancer role.Antioxidation is considered to be effective in many diseases such as prostate cancer,liver cancer,breast cancer and so on.Another important role of SFN is to act as an agonist of Nrf2,which can regulate the expression of Nrf2.A large number of experimental results show that sulforaphane can inhibit the proliferation and induce apoptosis of various tumor cells in vitro,and can effectively prevent liver cancer,lung cancer and so on.The occurrence of a variety of cancers is considered to have a good anti-oxidation,anti-cancer effects,UC is a type of disease that can occur carcinogenesis,regular review of colonoscopy is considered to be effective in preventing the occurrence of colon cancer,in view of this characteristic of SFN,Therefore,natural active substances such as sulforaphane,which have good antioxidant effect,were selected in this study.In view of the anti-cancer and antioxidant properties of SFN,whether it can regulate the expression of Nrf2 to slow down or prevent the development of ulcerative colitis.Caco-2 cell model was used to simulate the occurrence of ulcerative colitis,and the effect of SFN on the cell model was studied in this paper.To explore the role of SFN in the development of ulcerative colitis(UC)cell model and the mechanism of pathogenesis and prevention of ulcerative colitis(UC).Objective1.To explore whether SFN can slow down the inflammatory response of UC model cells.2.To explore the relationship between the activation of Nrf2 and the target genes of NLRP3/IL-1 ? axis in the model cells,and to determine whether SFN can protect UC through the regulation of Nrf2.MethodsIL-6,TNF-?,IFN-? and LPS were used to stimulate colon Caco-2 cells to simulate a complex inflammatory environment in which UC was located,in order to establish a cell model of ulcerative colitis.Different methods were used to detect the expression of inflammatory factors such as IL-8 in specific cell models to verify the success of the study.Nrf2 small interfering RNA(siRNA)was transfected into Caco-2 cells to detect the expression of Nrf2 and NLRP3/IL-1? axis target genes,and to verify the relationship between Nrf2 and NLRP3/IL-1 ? axis.Four kinds of inflammatory mediators were added to Caco-2 cells pretreated with SFN for 12 hours.The protective mechanism of sulforaphane on UC cell model by regulating Nrf2 pathway was studied by detecting the expression of Nrf2,NLRP3 and inflammatory factors.Results The cellular model simulates the inflammatory environment of ulcerative colitis in which Caco-2 cells are stimulated by mixed stimuli of different inflammatory mediators(mainly IL-6,TNF-?,IFN-? and LPS).PCR assay was used to detect the expression of inflammatory cytokines at the mRNA level and ELISA was used to detect the related inflammatory factors in the supernatant.The results showed that the expression of inflammatory mediators was up-regulated.Compared with the control group,the expression of Nrf2 gene in the knock-down model cells was up-regulated by NLRP3 and its downstream inflammatory factors in the siNrf2 group.After Caco-2 cells were pretreated with SFN before 12 hours,the expression of Nrf2 was up-regulated,and the expression of NLRP3 and inflammatory factors was down-regulated.Conclusion1.The model of ulcerative colitis was successfully established by stimulating colon Caco-2 cells with mixed inflammatory factors.2.SFN can significantly improve the inflammatory environment and inflammatory degree of UC.3.In UC cell model,Nrf2 can reduce the production of inflammatory factors by regulating the expression of target genes in the NLRP3/IL-1? axis and delay the inflammatory reaction.4.SFN can decrease the expression of inflammatory factors by regulating Nrf2.5.SFN may be a new drug adjuvant for the treatment of inflammatory bowel disease through the interaction of Nrf2 and NLRP3/IL-1? pathway,and provide a new target for clinical treatment.