Immunohistochemical characterization of the renal function in transplanted kidney in a carrier of an atypical uremic haemolitic syndrome due to factor H deficit

Abstract

The hemolytic uremic syndrome is characterized by microangiopathic hemolytic anemia, thrombocytopenia and acute renal failure. It is classified in typical, positive diarrhea, induced by Escherichia coli 0157-H7 (90%) and atypical, most commonly secondary to the deregulation of the alternative pathway of complement (3-10%). The chromosomal region 1q32 contains the regulatory system of the activation of human complement (RCA). It is related to mutations in regulatory factors of C3 as factor H (FH, the most common), the factor I, factor B and the constitutive membrane protein (MCP). It presents both dominant and recessive autosomic inheritance patterns. The autosomic dominant alteration of FH usually occurs in adults and mortality and the risk end stage kidney disease ranges between 50% - 90%.
The aim of our work was to study tubular and glomerular function by Immunohistochemistry techniques to detect transport mechanisms for water (AQPs), urea (UT-A) and proteins (nephrin, podocalyxin and megalin) in a transplanted kidney in a patient carrier of HUS by alterations in FH that developed a recurrence of HUS and nephrotoxicity injuries. We detect an adaptation mechanism to uremia by de novo expression of UT-A2 in renal cortex and the decrease of the UT-A1 in medulla and alterations in the proximal water transport by the decrease in the expression of AQP1 in proximal tubule. The changes at the level of the expression of the podocytic nephrin and podocalyxin and megalin in the proximal tubule may explain the presence of proteinuria.