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Development of gene expression signatures for murine bladder: Control vs. UTI89

ABSTRACT: Antimicrobial peptides (AMPs) serve key proposed roles in defending the urinary tract against invading uropathogens, but individual AMPs bearing greatest responsibility for these functions remain largely unknown. We identified RegIIIγ as the most transcriptionally upregulated AMP in bladder transcriptomes following uropathogenic Escherichia coli (UPEC) infection. We confirmed induction of RegIIIγ mRNA during cystitis and pyelonephritis by quantitative RT-PCR. Immunoblotting demonstrates increased bladder and urinary RegIIIγ protein levels following UPEC infection. Immunostaining localizes RegIIIγ protein to urothelial cells of infected bladders and kidneys. Human patients with cystitis and pyelonephritis exhibit increased urine levels of the orthologous HIP/PAP protein. Recombinant RegIIIγ protein does not demonstrate bactericidal activity toward UPEC in vitro, but does kill Staphylococcus saprophyticus in a dose-dependent manner. RegIIIγ knockout and control urinary tracts contain comparable bacterial burden following experimental inoculation of UPEC as well as Gram-positive uropathogens. Thus, while RegIIIγ and HIP/PAP expression occurs in human and murine UTI, their specific functions in the urinary tract remain uncertain.

ORGANISM(S): Mus musculus

PROVIDER: GSE72007 | GEO | 2015/12/29

SECONDARY ACCESSION(S): PRJNA292711

REPOSITORIES: GEO

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Project description:The kidney and bladder expresses a variety of powerful defense mechanisms to limit urinary infection including iron scavenging, a process called "nutritional immunity". We previously demonstrated that bladder and kidney epithelia generates the archetype of the urinary iron defense, a lipocalin called NGAL which binds Enterochelin, a bacterial siderophore. However, because urinary bacteria can evade the bacteriostatic effects of NGAL by modifying Enterochelin and by producing additional siderophores, other mechanisms of "nutritional immunity" are anticipated. To study the defense in the kidney, we used a cell type specific method of RNA isolation in mouse (adapted from Gay et al, Oregon). A promiscuous form of phosphoribosyltransferase (UPRT) was cloned into the Rosa26 locus using a floxed-stop design which we activated in a cell specific fashion with Atp6v1b1-Cre. Thiouracil was introduced 12hr and 24hrs after urinary tract infection. Isolation of RNA directly from intercalated revealed synthetic (Npas1-Bmal1-Alas), transport (Hrg1, Flvcr1) and metabolic enzymes (Hmox1) of heme metabolism. Hmox1 was detected in the kidney with a luciferase based reporter (Contag et al, Stanford) after infection. CO production was detected in vivo and in AtpCre-mTmG FACS isolated intercalated cells in vitro using a novel metal-based probe synthesized at Columbia (adapted from Liu et al, China). Urinary bacteria (UPEC) with heme transport mutations were not competitive in the colonization of the kidney but conversely were markedly stimulated by iron, suggesting bacterial-host competition for heme capture and metabolism. In fact, infection upregulated both heme synthetic and metabolic genes, suggesting that CO production is induced by infection. Exposure to CO terminated the growth of UPEC. In sum, we have identified an unusual iron trafficking system in the collecting ducts that mirrors the nutritional requirements of UPEC to achieve pyelonephritis. Many of these components are specific to the intercalated cells, consistent with the notion that these cells defend the urinary tract from infection.

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Development of gene expression signatures for murine bladder: Control vs. UTI89

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