Effect Of NLRP3 Inflammasome On Aging Bladder In Rats And Its Possible Mechanism

Objective: Bladder dysfunction is closely associated with the bladder fibrosis,which was caused by various factors.The pathogenies of bladder fibrosis mediated by inflammation has been confirmed by other studies.Moreover,fibrosis plays an important role in organ aging and functional degeneration.Therefore,this study was aimed to investigate the expression changes of inflammatory in the aging bladder and its possible mechanisms,and to explore the effect of NLRP3 inflammatory inhibitor Glyburide on aging bladder.Methods: We firstly examined the changes of urodynamic parameters and the expression of NLRP3 inflammatory in aging bladder and young bladder.Female SD rats were randomly divided into two groups according to the age: 2 months old group and 24 months old natural aging group,10 rats in each group.The urodynamic parameters of the two groups of rats were examined by the urodynamic instrument to determine the characteristics of bladder degeneration.Masson staining was used to evaluate the deposition of collagen,and to indicate the degree of bladder fibrosis.We also measure the expression of inflammatory NLRP3,Caspase1,IL1?,and senescenceassociated protein p21 by immunohistochemistry.The expression of NLRP3 and SIRT3 in inflammatory was detected by Western blot.Immunofluorescence was used to localize the key molecule Caspase1 and detect its relative expression.The possible mechanism of NLRP3 inflammatory in aging bladder is speculated.In the second part,NLRP3 inhibitor is applied in this part.We set up three groups: the young group,the aging control group,the aging Glyburide group,each group of 10 rats.The expression of inflammatory and aging related molecular of bladder tissues is detected in three groups.The collagen deposition and the urodynamic characteristics of aging bladder are confirmed.Finally,we explored the effect of Glyburide on the expression of NLRP3 in aging bladder and the mechanism of Glyburide on aging bladder dysfunction.Results: Urodynamic examination showed that the maximum volume and residual urine volume of the bladder was increased in the aging group,and the voiding time was also prolonged,which might be used to explain the phenomenon of bladder function degeneration.The expression of NLRP3 was significantly increased in the aging bladder.Furthermore,we found that the Caspase1 and IL1? was activated,and mainly located to the bladder urothelium.However,the deacetylase SIRT3 was significantly reduced in the aging group,while the senescence-related molecule p21 was significantly increased,which was conformed to the degree of aging of the bladder.Glyburide inhibits the activity of NLRP3 inflammatory in aging bladder.The expression of NLRP3 and IL1? protein in aging Glyburide group was lower than aging control group,but still higher than young group.Hematoxylin-eosin and Sirius Red staining demonstrated that the bladder wall was remodeled in the aging control group and the aging Glyburide group.The collagen/muscle fiber ratio of the aging bladder was decreased.There was no significant difference of the expression of the agingrelated protein p16 protein in the aging control and the aging Glyburide group.Conclusion: Our study demonstrated that aging bladder was associated with NLRP3 activation in inflammatory aging.Inflamm-aging might be a new mechanism to explain the degeneration of aging bladder.NLRP3/IL1? signaling pathway,played an important role in bladder functional deterioration.Glyburide could inhibit the activity of NLRP3 inflammatory in the aging bladder and delay the degeneration of bladder function.