[Contribution of experimental pathology to the understanding of human pyelonephritis]

The close similarities between the urinary tract of primates make it possible to use the monkey as a model for understanding the pathophysiology of pyelonephritis in the human. Basically, experimental protocols consist in introducing uropathogenic strains of E. coli into the bladder and/or the ureter in the monkey and to determine early and late consequences of the subsequent renal tissue infection. Lesions appear within the first minutes of bacterial invasion. They result from the virulence of the parasite, which pertains to multiple factors, with a prominent role of fimbrial adhesion. However, the defense mechanisms of the host better explain the renal tissue insult. They comprise early ischoemia due to granulocyte aggregation within the renal capillaries, followed by damage due to oxygen free radicals which are generated during reperfusion. The primate model of pyelonephritis is extremely useful to understand most clinical, functional and radiological events observed in the course of human pyelonephritis. This model also serves to test pharmacological manoeuvres aimed at preventing the renal tissue injury of pyelonephritis.