N TRAN1, MR SUTHERLAND1, TJ FLORES1, D RYAN1, L MOORE2, AL KENT3, JE DAHLSTROM3,4, JF BERTRAM1, VG PUELLES5, MJ BLACK1
1Monash University, Clayton, VIC; 2SA Pathology, Women’s and Children’s Hospital, and the University of Adelaide, Adelaide, SA; 3Canberra Hospital, Australian National University Medical School, Canberra, ACT; 4ACT Pathology, Canberra, ACT; 5RWTH Aachen University, Aachen, Germany
Aim: To determine the effects of chorioamnionitis on nephrogenesis and podocyte number in the developing human kidney.
Background: Chorioamnionitis, a common cause of preterm birth, is the inflammation of fetal membranes due to a bacterial infection during pregnancy. The fetal inflammatory response associated with chorioamnionitis has the potential to disrupt ongoing organ development, and is known to lead to organ injury. The specific impact of chorioamnionitis on nephron formation (nephrogenesis) in the human kidney, however, is unknown.
Methods: Archived kidney tissue was collected at autopsy from infants aged 21-28 weeks gestation (term = 38 weeks) that had been exposed (n=12), or unexposed (control, n=12), to chorioamnionitis in utero. Any intrauterine growth restricted infants were excluded. Nephrogenic zone width, glomerular generation number and glomerular maturity were assessed histologically. Immunofluorescent staining and stereology were used to assess glomerular volume, podocyte number, and podocyte density of inner-cortical glomeruli.
Results: There was no significant difference in kidney weight, nephrogenic zone width, glomerular generation number or glomerular maturity between groups. Average podocyte number (control: 697±16, chorioamnionitis: 657±15, p=0.08) and density (control: 2,163±75, chorioamnionitis: 1,978±64 per 105 µm3, p=0.07) per glomerulus tended to be lower in chorioamnionitis-exposed infants compared to controls, but this did not quite reach statistical significance.
Conclusions: Exposure to chorioamnionitis during gestation does not appear to significantly affect nephrogenesis or podocyte endowment in the kidneys of non-growth restricted infants.