Obesity promotes urinary tract infection by disrupting urothelial immune defenses

Obesity is a significant public health concern associated with increased infection risk, but the mechanisms remain unclear. Using a diet induced obesity mouse model, we investigate how obesity impacts urinary tract infection (UTI) susceptibility and bladder urothelial defenses. High fat diet-fed female and male C57BL/6 mice exhibit increased susceptibility to uropathogenic E. coli (UPEC) following experimental UTI. Transcriptomic analysis of bladder urothelial cells reveals sex-specific gene expression changes, but both sexes share activation of focal adhesion and extracellular matrix signaling. Western blot and immunostaining confirm activation of focal adhesion kinase (FAK), a central component of the focal adhesion pathway, in the bladders of obese female and male mice. Mechanistically, primary human urothelial cells overexpressing FAK exhibit increased UPEC invasion. These findings demonstrate that obesity enhances UTI susceptibility and identify FAK as a conserved pathway disrupted by obesity, contributing to increased UPEC vulnerability. Urothelium was isolated from bladders of female and male mice fed standard chow or high-fat diet for 8 or 12 weeks. RNA-seq was performed on urothelium, and comparisons were made between high-fat and standard chow-fed mice of the same sex and/or diet duration.