HUS and atypical HUS

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy characterized by intravascular hemolysis, thrombocytopenia, and acute kidney failure. HUS is usually categorized as typical, caused by Shiga toxin-producing Escherichia coli (STEC) infection, as atypical HUS (aHUS), usually caused by uncontrolled complement activation, or as secondary HUS with a coexisting disease. In recent years, a general understanding of the pathogenetic mechanisms driving HUS has increased. Typical HUS (ie, STEC-HUS) follows a gastrointestinal infection with STEC, whereas aHUS is associated primarily with mutations or autoantibodies leading to dysregulated complement activation. Among the 30% to 50% of patients with HUS who have no detectable complement defect, some have either impaired diacylglycerol kinase epsilon (DGK epsilon) activity, cobalamin C deficiency, or plasminogen deficiency. Some have secondary HUS with a coexisting disease or trigger such as autoimmunity, transplantation, cancer, infection, certain cytotoxic drugs, or pregnancy. The common pathogenetic features in STEC-HUS, aHUS, and secondary HUS are simultaneous damage to endothelial cells, intravascular hemolysis, and activation of platelets leading to a procoagulative state, formation of microthrombi, and tissue damage. In this review, the differences and similarities in the pathogenesis of STEC-HUS, aHUS, and secondaryHUSare discussed. Commonfor the pathogenesis seems to be the vicious cycle of complement activation, endothelial cell damage, platelet activation, and thrombosis. This process can be stopped by therapeutic complement inhibition in most patients with aHUS, but usually not those with a DGK epsilon mutation, and some patients with STEC-HUS or secondary HUS. Therefore, understanding the pathogenesis of the different forms of HUS may prove helpful in clinical practice.Peer reviewe

Life-threatening pregnancy-associated atypical haemolytic uraemic syndrome and its response to eculizumab

Pregnancy-associated atypical haemolytic uraemic syndrome (P-aHUS) is a rare, potentially lethal condition that can complicate pregnancy in up to 1 in 25 000 cases. Without prompt diagnosis and initiation of appropriate treatment, this condition can lead to disastrous consequences for both mother and child. Given the broad spectrum of conditions that can present similarly in the peripartum period, it is often difficult to establish the correct diagnosis in a timely manner. Recently, the terminal complement cascade inhibitor eculizumab has been used with considerable success in non-pregnancy HUS; however, its use in P-aHUS is limited to isolated case reports. Here, we present a case of fulminant P-aHUS in the postpartum period that was successfully treated with eculizumab resulting in significant recovery of renal function.No Full Tex

Microangiopatía trombótica secundaria y eculizumab: una opción terapéutica razonable

El conocimiento del papel del complemento en la patogenia del síndrome hemolítico urémico atípico y otras microangiopatías trombóticas (MAT) ha fomentado el desarrollo de la terapia anticomplemento con eculizumab más allá de su indicación original en la hemoglobinuria paroxística nocturna y en el síndrome hemolítico urémico atípico. La evidencia científica demuestra un estrecho límite entre MAT primarias y secundarias con activación del complemento subyacente en ambas. Por ello, el control del complemento se convierte en una diana terapéutica. El uso de eculizumab en MAT secundarias contempla 2 escenarios: diagnóstico diferencial difícil entre MAT primaria y secundaria (incluidos cuadros clínicos incompletos) o daño por complemento en procesos distintos, donde se demuestra la eficacia del tratamiento. Esta revisión es una síntesis de la evidencia científica sobre el papel de la activación del complemento en la fisiopatología de las MAT secundarias y la eficacia de la terapia anticomplemento en MAT asociadas a embarazo, fármacos, trasplante, rechazo humoral, enfermedades sistémicas y glomerulonefritis. La experiencia es aún limitada, pero la respuesta a eculizumab en pacientes con MAT secundarias graves y refractarias al tratamiento convencional abre una puerta a la investigación de la terapia anticomplemento como nueva opción terapéutica