DCHS1 DNA copy number loss associated with pediatric urinary tract infection risk

Abstract

Urinary tract infections (UTI), associated with vesicoureteral reflux (VUR), can lead to chronic kidney disease. Genetic alterations in the innate immune defenses contribute to UTI risk. We investigated a novel gene, Dachsous Cadherin-Related 1 (DCHS1), in children with UTI. We determined absolute DNA copy number (CN) of DCHS1 in children with UTI. In this case-control study, we utilized multiple complementary methods to determine the genomic CN of DCHS1. Children with (n = 370) and without (n = 71) VUR from two well-phenotyped clinical trials of UTI were copy-typed and compared to 491 healthy controls with no known history of VUR or UTI. Less than 1% of controls had a single copy of DCHS1, while 31% of children with UTI and no VUR and 7% of children with UTI and VUR had a single copy of the DCHS1 gene. Using immunostaining, we localized expression postnatally to the bladder and renal epithelia. Mice were also challenged with two uropathogenic Escherichia coli strains, and Dchs1 mRNA was quantified. This study represents the first report of DCHS1 in association with pediatric UTI. We hypothesize that its role in innate immunity is critical to lower urinary tract defense. Further investigation is required to determine the role of DCHS1 in innate immunity.

Keywords: DNA CN variations; pediatrics; urinary tract infections; vesicoureteral reflux.

Figure 1.

DCHS1 DNA copy number (CN) in subjects with UTI without vesicoureteral reflux (VUR), UTI with VUR, and controls. DCHS1 CN distribution and percentages in subjects with UTI without VUR (n = 71), UTI with VUR (n = 320), and controls (n = 491).

Figure 2.

DCHS1 DNA CNs 1 vs. ≥ 2 in subjects with UTI without VUR, UTI with VUR, and controls. Percentage and distribution of 1 CN vs. ≥ 2 CN of DCHS1 in subjects with UTI without VUR (n = 71), UTI with VUR (n = 320), and controls (n = 491). CN = DNA CN of DCHS1.

Figure 3.

Immunolocalization of DCHS1 in human kidney (upper and middle panel) and bladder (lower panel). Upper-left panel: kidney section showing V-ATPase E1-positive intercalated cell in collecting duct (green, white arrow); middle panel: DCHS1-positive cells (red, white arrow); and right-panel: merged image (white arrowheads) showing DCHS1-positive intercalated cells. Lower panel: bladder staining for DCHS1 indicated by arrows; left panel: 10× magnification showing islands of DCHS1 positive infiltrating cells; middle and right panel: 40× magnification, showing DCHS1-positive bladder urothelium. Blue nucleus staining DAPI, scale bar 50 µm.

Figure 4.

Dchs1 mRNA expression of murine bladder and kidneys in response to different uropathogenic E. coli strains. A and B graphs correspond to mRNA upregulation after 6 h on mouse bladder and kidneys infected with UTI89 compared to saline controls (n = 15 UTI89 and n = 15 saline). C and D graphs show mRNA transcripts of mouse bladder and kidneys upon inoculation with CFT073 compared to controls (n = 16 CFT073 and n = 15 saline), respectively. Long horizontal bars represent the mean, with upper and lower smaller horizontal bars representing ±1 standard deviation.