Identification of the Outer Membrane Immunoproteome of the Uropathogen Proteus mirabilis: Insights into Virulence and Potential Vaccine Candidates.

Proteus mirabilis, a gram negative bacterium, represents a common cause of complicated urinary tract infections (UTIs) in catheterized patients or those with functional or anatomical abnormalities of the urinary tract. To systematically identify surface-exposed antigens, proteins in the outer membrane fraction of bacteria were separated by 2D gel electrophoresis and subjected to Western blotting with sera from mice experimentally infected with P. mirabilis. Proteins recognized by sera were identified by mass spectrometry. Thirty-seven antigens (including 24 outer membrane proteins) to which a humoral response had been mounted were identified; these antigens are presumably expressed during infection and therefore represent potential virulence factors. Six representative antigens were selected for further study. Of these antigens, three played no apparent role in pathogenesis, as strains with isogenic mutations were not attenuated in the mouse model of ascending UTI: a putative secreted 5’-nucleotidase (PMI0047), RafY (PMI0288), and FadL (PMI1810). However, two putative iron acquisition proteins, PMI0842 and PMI2596, both contribute to fitness in the urinary tract. The sixth antigen, ZnuB (PMI1150), was annotated as the inner membrane component of the high affinity zinc (Zn2+) transport system ZnuACB. Components of this system have been shown to contribute to virulence in other pathogens; therefore, the role of ZnuACB in P. mirabilis was investigated by constructing a strain with an insertionally interrupted copy of znuC. The znuC::kan mutant was more sensitive to zinc limitation than wild type, was outcompeted by wild type in minimal medium, displayed reduced swimming and swarming motility, and produced less flaA transcript and flagellin protein. Production of flagellin and swarming motility were restored by complementation with znuCB in trans. Swarming motility was also restored by the addition of Zn2+ to agar prior to inoculation. ZnuC offers a competitive advantage during urinary tract infection. Since we demonstrated a role for PMI0842, PMI2596, and ZnuC in UTI, we hypothesize that there is limited iron and zinc present in the urinary tract and that P. mirabilis must scavenge these ions to colonize and persist in the host.Ph.D.Microbiology & ImmunologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/75895/1/gmontero_1.pd

Cytotoxic necrotizing factor 1 promotes prostate cancer progression through activating the Cdc42–PAK1 axis

Uropathogenic Escherichia coli (UPEC) is the leading cause of urinary tract infections and plays a role in prostatic carcinogenesis and prostate cancer (PCa) progression. However, the mechanisms through which UPEC promotes PCa development and progression are unclear. Cytotoxic necrotizing factor 1 (CNF1) is one of the most important UPEC toxins and its role in PCa progression has never been studied. We found that UPEC‐secreted CNF1 promoted the migration and invasion of PCa cells and PCa metastasis. In vitro studies showed that CNF1 promotes pro‐migratory and pro‐invasive activity through entering PCa cells and activating Cdc42, which subsequently induced PAK1 phosphorylation and up‐regulation of MMP‐9 expression. CNF1 also promoted pulmonary metastasis in a xenograft mouse model through these mechanisms. PAK1 phosphorylation correlated with advanced grades of PCa in human clinical PCa tissues. These results suggest that CNF1 derived from UPEC plays an important role in PCa progression through activating a Cdc42–PAK1 signal axis and up‐regulating the expression of MMP‐9. Therefore, surveillance for and treatment of cnf1‐carrying UPEC strains may diminish PCa progression and thus have an important clinical therapeutic impact. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138311/1/path4940.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138311/2/path4940_am.pd

Immune modulation by group B Streptococcus influences host susceptibility to urinary tract infection by uropathogenic Escherichia coli

Urinary tract infection (UTI) is most often caused by uropathogenic Escherichia coli (UPEC). UPEC inoculation into the female urinary tract (UT) can occur through physical activities that expose the UT to an inherently polymicrobial periurethral, vaginal, or gastrointestinal flora. We report that a common urogenital inhabitant and opportunistic pathogen, group B Streptococcus (GBS), when present at the time of UPEC exposure, undergoes rapid UPEC-dependent exclusion from the murine urinary tract, yet it influences acute UPEC-host interactions and alters host susceptibility to persistent outcomes of bladder and kidney infection. GBS presence results in increased UPEC titers in the bladder lumen during acute infection and reduced inflammatory responses of murine macrophages to live UPEC or purified lipopolysaccharide (LPS), phenotypes that require GBS mimicry of host sialic acid residues. Taken together, these studies suggest that despite low titers, the presence of GBS at the time of polymicrobial UT exposure may be an overlooked risk factor for chronic pyelonephritis and recurrent UTI in susceptible groups, even if it is outcompeted and thus absent by the time of diagnosis