Renal lesions in young rats induced by Salmonella enteritidis endotoxin.

Sepsis in newborns and infants is a major pediatric problem often associated with renal dysfunction. The present report deals with changes in renal tissue induced by Salmonella enteritidis endotoxin in 10- and 28-day-old Sprague-Dawley rats. Our studies revealed a 90% lethality within 24 h of 0.1 mg/kg and 35 mg/kg S. enteritidis endotoxin injection in 10- and 28-day-old rats, respectively. The 10- and 28-day-old animals received a single intraperitoneal injection of the 90% lethality dose and were sacrificed at different intervals for histopathological evaluation of kidneys by light and electron microscopy. The glomeruli showed visceral epithelial and endothelial cell swelling and polymorphonuclear leukocyte and platelet accumulation in the capillary lumina. Cortical and medullary tubules showed edematous separation, mild focal epithelial cell damage and focal intertubular hemorrhage. Renal sections of 28-day-old experimental rats showed increased numbers of polymorphs in the glomerulus and enlarged mesangial matrix. These sections also showed an increase in the number of hemorrhagic foci in 10 x field compared with the 10-day-old experimental rats. Endothelial cells of renal vasculature showed cytoplasmic swelling, vacuolization, autophagic vesicle formation and presence of secondary lysosomes. Changes in the endothelial cells of peritubular microvasculature were extensive, resulting in focal degeneration and partial loss of endothelial lining. These studies show that infant rats are extremely sensitive to S. enteritidis endotoxin requiring 1/350 the dose given to young adults to induce histopathological changes in kidney; the endothelial cells of microvasculature appear to be the primary targets of endotoxic injury irrespective of age.