腎臓学と治療学ジャーナル

Hemolytic Uremic Syndrome in Post-Infectious Glomerulonephritis: Possible Pathophysiological Mechanisms

Abstract

Jean-Claude Davin, Jaap W. Groothoff, Michiel Oosterveld, Rixt Schriemer, Nicole van de Kar, Antonia Bouts and Sandrine Florquin

Malignant hypertension is able to induce glomerular Thrombotic Microangiopathy (TMA) and Hemolytic Uremic Syndrome (HUS) in the absence of Glomerulonephritis (GN). It is therefore commonly admitted that hypertension is the only cause of Glomerular Endothelial Cells (GEC) damage leading to TMA and HUS observed in GN. However, recent literature on TMA in IgA nephropathy calls this hypothesis into question. It is also questionable why so few cases of HUS are reported in association with Post-Infectious GN (PIGN) for which more than 50% of cases necessitate anti-hypertension treatment, we report the case of a 10 years old girl presenting with an extensive cutaneous streptococcal infection, hematuria, nephrotic syndrome, hypertension (146/106) and HUS needing dialysis. The kidney biopsy revealed a severe exudative GN, 30% of crescentic glomeruli and TMA. Immunofluorescence and electron microscopy suggested intense complement activation at the basal level of GEC and podocytes. Genotyping of complement factors was normal. A rapid recovery of a normal renal function was observed after intensive Plasma Exchange (PE) therapy. We speculate that a high amount of group A streptococcal (GAS) toxins produced in extensive cutaneous lesions might have facilitated TMA initiation by: 1/ a direct damage of endothelial cells; 2/ an intense complement activation induced by the binding of GAS toxins to the complement factor H (CFH), leading to GEC and podocytes’ lesions. The favorable effect of PE can be explained by removal of GAS toxins and inactivated CFH on one side and by supply of free CFH on another side. Multicentre studies should be initiated in order to evaluate the frequency and the pathophysiology of TMA and HUS in PIGN.