D-mannose ameliorates age-associated cellular senescence in the bladder urothelium and NLRP3/Gasdermin/IL-1β -driven pyroptotic epithelial cell shedding
Aging is a risk factor for disease via increased susceptibility to infection, decreased ability to maintain homeostasis, inefficiency in combatting stress, and decreased regenerative capacity. Multiple diseases including urinary tract infection (UTI), are more prevalent with age; however, the mechanisms underlying how aging affects the urinary tract mucosa and the reason why aging correlates with disease are poorly understood. Here, we show that, relative to young (8-12 weeks) mice, the urothelium of aged (18-24 months) female mice accumulates large lysosomes with decreased acid phosphatase activity and shows overall decreased autophagic flux. Aged bladders exhibit basally high accumulation of reactive oxygen species (ROS) and dampened redox response. Furthermore, the aged urothelium exhibits a canonical senescence-associated secretory phenotype (SASP) at baseline with continuous NLRP3-inflammasome- and Gasdermin D (GSDMD)-dependent pyroptotic cell death. Accordingly, we find that aged mice chronically exfoliate epithelial cells. When infected with uropathogenic E. coli, infected aged mice harbor more bacterial reservoirs post-infection and are prone to spontaneous recurrent UTI. Finally, treatment of aged mice with D-Mannose, a natural bioactive monosaccharide, rescues autophagy flux, reverses SASP, and limits pyroptotic epithelial shedding. Thus, normal aging dramatically affects bladder physiology with aging alone increasing baseline cellular stress and susceptibility to infection. Additionally, our results suggest that mannose supplementation could serve as a senotherapeutic to limit age-associated urothelial dysfunction.