title: Ribonuclease 7 is a potent antimicrobial peptide within the human urinary tract.
abstract: Although the urinary tract is constantly challenged by microbial invasion, it remains free from colonization. Although little is known about how the urinary tract maintains sterility, the presence of antimicrobial peptides (AMPs) in the urine suggests that they may play a role in its protection from infection. Ribonuclease 7 (RNase 7) is a potent AMP that was first identified in the skin. Here, we characterize the expression and relevance of RNase 7 in the human kidney and urinary tract. Using RNA isolated from healthy human tissue, we performed quantitative real-time PCR and found basal RNASE7 expression in kidney and bladder tissue. Immunohistochemical and immunofluorescent analysis localized RNase 7 to the urothelium of the bladder, ureter, and the intercalated cells of the collecting tubules. In control urine samples from healthy individuals, the concentration of RNase 7 was found to be in the low micromolar range; very abundant for an AMP. Antibacterial neutralization assays showed that urinary RNase 7 has potent antimicrobial properties against Gram-negative and Gram-positive uropathogenic bacteria. Thus, RNase 7 is expressed in the human kidney and urinary tract and it may have an important antimicrobial role in maintaining tract sterility.
authors.affiliation: Pediatric Nephrology Fellowship Program, Nationwide Children's Hospital, The Ohio State University, Columbus, Ohio, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Spencer
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Schwaderer
authors.forename: Julianne D
authors.initials: JD
authors.lastname: Dirosario
authors.forename: Kirk M
authors.initials: KM
authors.lastname: McHugh
authors.forename: Glen
authors.initials: G
authors.lastname: McGillivary
authors.forename: Sheryl S
authors.initials: SS
authors.lastname: Justice
authors.forename: Ashley R
authors.initials: AR
authors.lastname: Carpenter
authors.forename: Peter B
authors.initials: PB
authors.lastname: Baker
authors.forename: Jürgen
authors.initials: J
authors.lastname: Harder
authors.forename: David S
authors.initials: DS
authors.lastname: Hains
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000032:analysis; D001419:Bacteria / Q000276:immunology; D006801:Humans; D007668:Kidney / Q000201:enzymology / Q000276:immunology; D060888:Real-Time Polymerase Chain Reaction; D012260:Ribonucleases / Q000032:analysis* / Q000235:genetics / Q000276:immunology*; D014018:Tissue Distribution; D001743:Urinary Bladder; D014551:Urinary Tract / Q000201:enzymology* / Q000276:immunology; D019459:Urothelium
chemical_list: D023181:Antimicrobial Cationic Peptides; D012260:Ribonucleases; C470000:Ribonuclease 7