Evaluation of cytochrome c in hemolytic uremic syndrome

Abstract

Hemolytic uremic syndrome (HUS) results from thrombotic microangiopathy following injury to vascular endothelial cells. Notably, the involvement of apoptosis has been considered to be one of the etiologies of HUS. Cytochrome c is a marker of apoptosis and has a positive correlation with the severity of acute encephalopathy. However, there have been no reports regarding HUS cases with or without encephalopathy. Here we report a case of HUS caused by enterohemorrhagic Escherichia coli O157 in a 4-year-old girl, in which serum cytochrome c levels were evaluated during different phases of acute encephalopathy. Her serum cytochrome c levels were high and fluctuated followed by neurological status. Additionally, we evaluated the association between serum cytochrome c levels and clinical features in 9 patients with HUS. Serum cytochrome c levels were higher in HUS cases complicated with encephalopathy and/or acute kidney injury with an estimated glomerular filtration rate under 20 ml/min/1.73 m². Our study suggests that apoptosis contributes to the pathophysiology of HUS, and that cytochrome c might be a useful marker for assessing its severity, especially in HUS cases with encephalopathy or acute kidney failure requiring dialysis. Further studies with a larger number of patients are required to clarify these associations.