Contribution of immune modulation, metabolism, and microbiota to Group B Streptococcal urinary tract infection

PROJECT SUMMARY Urinary tract infection (UTI) is a major medical burden, afflicting more than half of women at least once in their lifetime, and generating more than $2 billion of healthcare costs annually in the United States. UTI is typically considered a mild medical condition in healthy adults and is readily cured by oral antibiotics. However, hosts with aberrant antimicrobial defenses or metabolic dysfunction, such as type 2 diabetes, are twice as likely to develop UTI and often develop complications including recurrent UTI, pyelonephritis, and urosepsis. Certain pathogens, such as Group B Streptococcus (GBS) are curiously over-represented in diabetes, and may highlight unique deficiencies in host urinary defenses in these patients. The goal of this proposed research is to identify the dysfunctional molecular pathways of the diabetic urogenital tract conferring heightened susceptibility, increased virulence, and/or increased colonization by GBS. Our published and preliminary studies show deficient urinary antimicrobial defense factors and amplified GBS UTI susceptibility in diabetic mice, enhanced GBS fitness in diabetic levels of glucose, and increased GBS vaginal colonization in diabetic mice. These data support the central hypothesis that aberrant function of essential urinary defenses, augmented bacterial virulence, and/or disparate vaginal microbiota enhance susceptibility to GBS urogenital infection in type 2 diabetes. This hypothesis will be interrogated through the following specific aims: 1) Interrogate the role of Tamm-Horsfall glycoprotein (THP) in epithelial defense and immune modulation during GBS UTI, 2) Assess impact of urinary glucose levels on GBS bladder colonization and urinary tract immune responses, and 3) Define the impact of host metabolism and the vaginal microbiota on GBS colonization. These aims are advanced using multiple innovative tools including longitudinal glycan analyses, high-throughput cultivation of vaginal microbial communities, bioluminescent bacterial imaging, transgenic mouse lines, recently established humanized microbiota models of GBS vaginal colonization, and modern microbiome and metabolome profiling. This research takes place in the dynamic and interdisciplinary environment of Baylor College of Medicine with diverse expertise in GBS-host interactions, microbiome characterization and cultivation, and clinical management of type 2 diabetes. This research strategy seeks to more fully understand the complex processes diminishing host defenses during metabolic disease to inform new therapeutic targets that can treat or prevent UTI in both healthy individuals and those with type 2 diabetes.