Alterations of glomerular podocytic processes in immunologically mediated glomerular disorders

Abstract

The importance of the relationship between the alteration of podocytic processes (PP) and proteinuria has been controversial for almost 30 years. In spite of several morphometric studies the range of PP alterations in different proteinuric conditions has gone unnoticed. Thus, we studied the distribution of abnormally broadened PP in different glomerulopathies and in normal controls (children and adults). We found a highly variable mean PP-width in all proteinuric patients, values that were, however, always clearly distinct from normal controls in children and adults. A correlation between the extent of PP alteration and the amount of proteinuria was not found (r = 0.09) for the group as a whole or for the different clinico-pathological entities. In proteinuric patients 15 to 50% of all PP were broadened and covered 40 to 60% of the total length of the peripheral capillary loop. We conclude that the alteration of PP in various proteinuric conditions is variable and does not correlate with the level of proteinuria. These studies further suggest that other mechanisms, possible hemodynamic adaptation in response to the capillary wall injury, might play a role in the permeability changes observed in these patients.