Vascular permeability factors in steroid-sensitive nephrotic syndrome and focal segmental glomerulosclerosis

The concept that some forms of proteinuria may be induced by the action of circulating systemic permeability factors on the glomerular capillary wall is intriguing. First proposed in the 1970s in the context of steroid-sensitive nephrotic syndrome, the immune system was proposed as a source of such a vascular permeability factor (VPF). More recently, some forms of focal segmental glomerular sclerosis appear to be associated with another type of systemic factor. This paper reviews the evidence for such factors and compares the properties of a number of candidate VPFs.