Browsing by Author "Wolfe, Alan J."

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    Asymptomatic Bacteriuria versus Symptom Underreporting in Older Emergency Department Patients with Suspected Urinary Tract Infection
    (Wiley, 2020-11) Caterino, Jeffrey M.; Stephens, Julie A.; Camargo, Carlos A., Jr.; Wexler, Randell; Hebert, Courtney; Southerland, Lauren T.; Hunold, Katherine M.; Hains, David S.; Bischof, Jason J.; Wei, Lai; Wolfe, Alan J.; Schwaderer, Andrew; Pediatrics, School of Medicine
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    Development and validation of a high-throughput cell-based screen to identify activators of a bacterial two-component signal transduction system
    (ACC, 2015-07) van Rensburg, Julia J.; Fortney, Kate R.; Chen, Lan; Krieger, Andrew J.; Lima, Bruno P.; Wolfe, Alan J.; Katz, Barry P.; Zhang, Zhong-Yin; Spinola, Stanley M.; Department of Microbiology and Immunology, IU School of Medicine
    CpxRA is a two-component signal transduction system (2CSTS) found in many drug-resistant Gram-negative bacteria. In response to periplasmic stress, CpxA autophosphorylates and donates a phosphoryl group to its cognate response regulator, CpxR. Phosphorylated CpxR (CpxR-P) upregulates genes involved in membrane repair and downregulates multiple genes that encode virulence factors, which are trafficked across the cell membrane. Mutants that constitutively activate CpxRA in Salmonella enterica serovar Typhimurium and Haemophilus ducreyi are avirulent in mice and humans, respectively. Thus, the activation of CpxRA has high potential as a novel antimicrobial/antivirulence strategy. Using a series of Escherichia coli strains containing a CpxR-P-responsive lacZ reporter and deletions in genes encoding CpxRA system components, we developed and validated a novel cell-based high-throughput screen (HTS) for CpxRA activators. A screen of 36,000 compounds yielded one hit compound that increased reporter activity in wild-type cells. This is the first report of a compound that activates, rather than inhibits, a 2CSTS. The activity profile of the compound against CpxRA pathway mutants in the presence of glucose suggested that the compound inhibits CpxA phosphatase activity. We confirmed that the compound induced the accumulation of CpxR-P in treated cells. Although the hit compound contained a nitro group, a derivative lacking this group retained activity in serum and had lower cytotoxicity than that of the initial hit. This HTS is amenable for the screening of larger libraries to find compounds that activate CpxRA by other mechanisms, and it could be adapted to find activators of other two-component systems.
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    Interplay between bladder microbiota and urinary antimicrobial peptides: mechanisms for human urinary tract infection risk and symptom severity
    (PLoS, 2014-12-08) Nienhouse, Vanessa; Gao, Xiang; Dong, Qunfeng; Nelson, David E.; Toh, Evelyn; McKinley, Kathleen; Schreckenberger, Paul; Shibata, Noriko; Fok, Cynthia S.; Mueller, Elizabeth R.; Brubaker, Linda; Wolfe, Alan J.; Radek, Katherine A.; Department of Microbiology and Immunology, IU School of Medicine
    Resident bacterial communities (microbiota) and host antimicrobial peptides (AMPs) are both essential components of normal host innate immune responses that limit infection and pathogen induced inflammation. However, their interdependence has not been investigated in the context of urinary tract infection (UTI) susceptibility. Here, we explored the interrelationship between the urinary microbiota and host AMP responses as mechanisms for UTI risk. Using prospectively collected day of surgery (DOS) urine specimens from female pelvic floor surgery participants, we report that the relative abundance and/or frequency of specific urinary microbiota distinguished between participants who did or did not develop a post-operative UTI. Furthermore, UTI risk significantly correlated with both specific urinary microbiota and β-defensin AMP levels. Finally, urinary AMP hydrophobicity and protease activity were greater in participants who developed UTI, and correlated positively with both UTI risk and pelvic floor symptoms. These data demonstrate an interdependency between the urinary microbiota, AMP responses and symptoms, and identify a potential mechanism for UTI risk. Assessment of bacterial microbiota and host innate immune AMP responses in parallel may identify increased risk of UTI in certain populations.