Insulin receptor signaling regulates renal collecting duct and intercalated cell antibacterial defenses

J Clin Invest. 2018 Dec 3;128(12):5634-5646. doi: 10.1172/JCI98595. Epub 2018 Nov 12.

Abstract

People with diabetes mellitus have increased infection risk. With diabetes, urinary tract infection (UTI) is more common and has worse outcomes. Here, we investigate how diabetes and insulin resistance impact the kidney's innate defenses and urine sterility. We report that type 2 diabetic mice have increased UTI risk. Moreover, insulin-resistant prediabetic mice have increased UTI susceptibility, independent of hyperglycemia or glucosuria. To identify how insulin resistance affects renal antimicrobial defenses, we genetically deleted the insulin receptor in the kidney's collecting tubules and intercalated cells. Intercalated cells, located within collecting tubules, contribute to epithelial defenses by acidifying the urine and secreting antimicrobial peptides (AMPs) into the urinary stream. Collecting duct and intercalated cell-specific insulin receptor deletion did not impact urine acidification, suppressed downstream insulin-mediated targets and AMP expression, and increased UTI susceptibility. Specifically, insulin receptor-mediated signaling regulates AMPs, including lipocalin 2 and ribonuclease 4, via phosphatidylinositol-3-kinase signaling. These data suggest that insulin signaling plays a critical role in renal antibacterial defenses.

Keywords: Immunology; Insulin signaling; Nephrology; UTI/pyelonephritis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Infections / genetics
  • Bacterial Infections / metabolism*
  • Bacterial Infections / microbiology
  • Bacterial Infections / pathology
  • Diabetes Mellitus, Experimental / genetics
  • Diabetes Mellitus, Experimental / metabolism*
  • Diabetes Mellitus, Experimental / microbiology
  • Diabetes Mellitus, Experimental / pathology
  • Diabetes Mellitus, Type 2 / genetics
  • Diabetes Mellitus, Type 2 / metabolism*
  • Diabetes Mellitus, Type 2 / microbiology
  • Diabetes Mellitus, Type 2 / pathology
  • Kidney Tubules, Collecting / metabolism*
  • Kidney Tubules, Collecting / microbiology
  • Kidney Tubules, Collecting / pathology
  • Mice
  • Mice, Mutant Strains
  • Receptor, Insulin / genetics
  • Receptor, Insulin / metabolism*
  • Signal Transduction*
  • Urinary Tract Infections / genetics
  • Urinary Tract Infections / metabolism*
  • Urinary Tract Infections / pathology
  • alpha-Defensins / genetics
  • alpha-Defensins / metabolism

Substances

  • alpha-Defensins
  • Receptor, Insulin