Urinary tract infections (UTIs) represent one of the most common bacterial infections of humans. Recurrence and persistence of UTIs, in spite of appropriate antibiotic therapry, has been attributed, at least in part, to the pathogen seeking intracellular refuge within bladder cells. Type 1 fimbriated uropathogenic E.coli (UPEC) accounts for over 80% of all UTIs. The virulence of the bacteria is associated with its capacity to invade the superficial bladder epithelium and avoid elimination in the urine. We have recently discovered that during infection in an experimental model of UTI, UPEC were entering and harboring within fusiform vesicles of superficial epithelial cells of the bladder. Remarkably, artificially boosting intracellular levels of cAMP in BECs induced bacterial expulsion from infected BECs, and also impeded bacterial invasion of BECs. Conceivably, use of artificial enhancers of cAMP to reduce entry and to expel bacteria from intracellular niches could be of therapeutic value. In pilot experiments, we have successfully eliminated bacteriurea in UPEC infected mice following intraperitoneal instillation of forskolin, a cAMP booster. Forskolin (a derivative of the plant herb Coleus forskohlii) is unlikely to be toxic to humans considering that Coleus forskohlii extracts have been employed for medicinal purposes for centuries in Asia. In the US, use of forskolin for a variety of ailments is rapidly increasing as interest in alternative medicine has grown.
The specific aims are to: (i) Employ an ex vivo model of bladder infection, to demonstrate (a), the dependence of UPEC on intracellular cAMP levels during invasion of BECs and (b), the ability to manipulate bacterial burden in infected BECs with modulators of cAMP. (ii) Elucidate the molecular events leading to how intracellular cAMP negatively modulates UPEC invasion into BECs and how artificially increasing cAMP levels triggers bacterial expulsion.(iii) Examine the efficacy of forskolin treatment as an alternative or complement to antibiotic therapy for UTIs. The proposed studies should provide valuable information on the role of cAMP as a potent modulator of bacterial invasion and expulsion from BECs.
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