| BACKGROUND AND PURPOSEUrinary tract infection(UTI)is the most common recurrent infection in humans,usually caused by various pathogens,the most common of which is Uropathogenic Escherichia coli(UPEC),which accounts for about all 80%of urinary tract infections.Urinary tract infections can be divided into upper urinary tract infections,including pyelonephritis and ureteritis;lower urinary tract infections,including cystitis and urethritis.Clinically,antibiotics are used to treat urinary tract infections,but a considerable number of patients suffer from repeated infections.With the continued emergence of antibiotic resistance,coupled with our increasing understanding of the role of symbiotic members of the host microbiota,we urgently need to explore therapies to reduce antibiotics.Uropathogenic Escherichia coli(UPEC)has a large number of pathogenic factors,including fibronectin,exotoxin and flagella.α-hemolysin(α-hemolysin,HlyA)is a major pathogenic exotoxin secreted by UPEC,which can cause serious urinary tract infections,such as acute pyelonephritis and sepsis.In urinary tract infections caused by UPEC,whether the diseased strain secretes HlyA is positively correlated with the severity of symptoms.Innate immune responses are the body’s first line of defense against UPEC infection.During urinary tract infections,UPEC can secrete the exotoxin HlyA to inhibit the metabolic enzyme ATP citrate cleavage(ACLY),resulting in a decrease in the level of acetyl-CoA,resulting in a decrease in the acetylation of H3K9 histones in the CXCL8 promoter region,which leads to immunity Inhibit the effect,thereby evading the body’s natural immune response.Previous in vitro experiments found that after UPEC infection,supplementation with acetate can partially reverse histone deacetylation.Urinary tract infection is currently the most common bacterial infectious disease worldwide.Approximately 150 million people get sick every year,and even about 1%of severe patients require hospitalization.The huge medical expenses have caused a serious economic burden.It is foreseeable that if urinary tract infections can be effectively prevented and treated,huge social and economic benefits will be produced.METHOD1.At the cellular level,after treatment with UPEC and HDM strain lacking in HlyA respectively,Western-Blot and PCR were used to test the immunosuppressive effect of UPEC infection.2.The UPEC and HDM strains were used to construct mouse urinary tract infection models.The acetate treatment group was intraperitoneally injected with acetate on the day before treatment,the first day,the third day,and the fifth day after treatment,and the infected mice were collected urine,the bacterial load of the bladder was detected by the bacterial coating plate method to verify the success of the model.3.Collect mouse bladder tissue 1 day after infection,and detect histone acetylation by immunofluorescence4.Collect mouse bladder tissue 1 day after infection,PCR to detect Cxcll expression in bladder tissue,and flow cytometry to detect inflammatory cells in bladder tissue.5.Collect mouse bladder tissues 1,4,and 7 days after infection,and perform histopathological scoring after HE staining.RESULT1.In vitro,UPEC and HDM were used to infect bladder epithelial cells(BECs,line 5637).Cell protein was extracted and PCR method was performed.The results showed that UPEC did not significantly induce inflammatory gene expression,and HDM treatment group showed a high level of inflammation.Gene,WesternBlot method,found that UPEC and HDM can activate the NF-κB signaling pathway(P<0.05).2.The mouse bladder tissue after 1 day of infection was collected and subjected to immunofluorescence.The results showed that UPEC reduced the level of histone acetylation,and the level of histone acetylation after acetate pretreatment was significantly increased(P<0.05).3.Collect mouse bladder tissue after 1 day of infection,homogenize the tissue,and perform PCR.The results show that the expression level of Cxcl1 in UPEC group is much lower than that of acetate pretreatment group and HDM group.Flow cytometry results show neutrophils in bladder tissue The number of UPEC group was much lower than that of acetate pretreatment group and HDM group(P<0.05).4.The mouse bladder tissues were collected 1,4,and 7 days after infection.The HE staining results showed that the HDM group had the highest histopathological score one day after infection,and then steadily decreased,while the UPEC group histopathological score gradually increased and reached the first day.Maintain the highest level for 7 days(P<0.05).CONCLUSION1.UPEC can activate the NF-κB pathway,but does not promote the expression of pro-inflammatory factors.2.Acetate supplementation in vitro can partially reverse the histone acetylation induced by UPEC exotoxin HlyA and improve the inhibition of inflammation.3.Acetate can improve cystitis caused by UPEC. |
