Mechanisms of Glucocorticoid Resistance in Idiopathic Nephrotic Syndrome

Nephrotic syndrome, characterized by massive proteinuria, hypoalbuminemia and edema, is one of the most common kidney diseases in children. Although glucocorticoids (GCs), the mainstay of therapy for over 50 years, are effective in most children, more than 20% develop GC resistant nephrotic syndrome (SRNS), among whom focal segmental glomerular sclerosis (FSGS) is a frequent pathological outcome and the cause of endstage renal disease with a prevalence of 4% in the USA. Despite its clinical importance, the molecular basis of SRNS is unknown. In recent years, researchers have not only gained a new understanding of the roles of structural and functional abnormalities in GC receptors (GRs) in GC resistance, but have also gradually discovered close relationships between GC resistance in idiopathic nephrotic syndrome and podocyte-related molecules, like slit diaphragm (SD) molecules and so on. Here we mainly discussed these molecules and their physiological as well as pathological effects, including nephrin, podocin, CD2-associated protein (CD2AP), α-actinin-4, transient receptor potential cation channel 6 (TRPC6), phospholipase C epsilon-1 (PLCe1), Wilms’ tumor suppressor gene 1 (WT1), Lmx1b, LAMB2, myosin 1e (MOY1E) and inverted formin 2 (IFN2). Mitochondrial cytopathies are also involved in GC resistance and well-reviewed [1, 2], which will not be discussed in detail in this review. To those SRNS without any genetic defects, immunological disturbances are always involved and should be stressed. In this article, recent progress in research on the mechanisms of GC resistance in idiopathic nephrotic syndrome is reviewed.