Does undernutrition program renal glomerular injury leading to focal segmental glomerulosclerosis?

The number of babies of low birth weight (BW) and children with focal segmental glomerulosclerosis have been increasing. Also, adverse events during development increase disease risk in later life, but causal relationships among these facts remain unclear. Using a unique avian model, in which nutritional supply can be reduced unaffected by maternal circulation, we examined whether undernutrition during development retards nephrogenesis, resulting in fewer nephrons and in glomerular injury leading to nephrosclerosis. We found that in Japanese quail, Coturnix japonica, partial egg white withdrawal (EwW, 5‐8%, 8–9%, 10%) before incubation decreased BW by 8.7%, 15.2%, and 15.4%, respectively. In EwW birds vs. controls (CT), hatching rate and kidney size were lower, and more immature glomeruli were seen at the surface area. Also, the number of glomeruli (cortical region, mm 2 ) in mature EwW quail was lower (CT 38.2±3.2, 5–8% EwW 28.3±1.8; CT 34.67±1.4, 8–9% EwW 21.0±1.15). In EwW kidneys, some glomerular podocytes had tall/thin foot processes and contained numerous vacuoles, but immunoreactive podocin and slit diaphragms were clearly seen. Mesangial areas are expanded with edematous appearance. These results suggest that undernutrition during development delays nephrogenesis and reduces the number of mature nephrons. Damaged or incompletely mature glomeruli may proceed to nephrosclerosis. (Grant‐in‐Aid for Sci. Research from Japan Ministry for Education 21390307)