Henoch-Schönlein Purpura Nephritis Causes and Its Relationship with IgA

Henoch-Schönlein purpura nephritis is a rare kidney disease leading to chronic kidney disease. Although retrospective studies suggest beneficial effects of some therapies, prospective randomized clinical trials proving treatment efficacy are still lacking. In view of this, we should find out its causes and then prevent them.

Henoch-Schonlein purpura is a type of vasculitis and inflammatory response within the blood vessel that has symptoms of purple spots on the skin, joint pain, gastrointestinal symptoms, and glomerulonephritis. It is usually seen in children (more commonly boys than in girls), but people of any age may be affected. Many have had an upper respiratory illness in the previous weeks. However, the pathogenesis of HSP remains unknown.

It is generally considered to be an immune complex-mediated disease characterized by the presence of polymeric IgA1containing immune complexes predominantly in dermal, gastrointestinal, and glomerular capillaries. The pathognomonic granular IgA and C3 deposits in the mesangium are indistinguishable from those seen in IgA nephropathy. Similar immunohistologic findings have also been observed in the kidneys of patients with liver cirrhosis, dermatitis herpetiformis, celiac disease, and chronic inflammatory disease of the lung.

The relationship between IgA nephropathy and HSP remains obscure, since the pathogenesis of both are still enigmatic despite the considerable information presented. However, a good deal of evidence suggests that the two disorders are pathogenetically linked. Many (but not all) patients with both disorders have increased serum IgA levels and IgA-containing CIC. Other observations in favor of a hypothesis of commonality include the indistinguishable nature of the renal histopathologic lesion, the presence of clinically silent but histologically detectable IgA deposits in dermal and gastrointestinal tissue in patients with Berger's disease, and the occasional report of HSP occurring in patients with prior long-term IgA nephropathy. Finally, one of two identical twin brothers simultaneously infected by proven adenovirus developed severe HSP nephritis progressing to chronic renal insufficiency, while the other developed Berger's disease with recurrent asymptomatic hematuria.