Apoptosis in CADASIL: An in vitro study of lymphocytes and fibroblasts from a cohort of Italian patients

Abstract

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary disease affecting vascular smooth muscle cells of nearly all tissues. Clinical manifestations mainly concern the central nervous system with repeated TIA/stroke, migraine, psychiatric disturbances, and cognitive decline. Minor findings have been reported in muscle, nerve, and skin. CADASIL is due to NOTCH3 gene mutations. This gene has been identified as an up-regulator of c-FLIP, an inhibitor of Fas-ligand-induced apoptosis. The aim of this study was to assess the involvement of oxidative stress-induced apoptosis in cells from 16 Italian CADASIL patients. Peripheral blood lymphocytes (PBLs) and fibroblasts from CADASIL patients were exposed to 2-deoxy-D-ribose (dRib), which induces apoptosis by oxidative stress. Apoptosis was analyzed by flow cytometry, agarose gel electrophoresis and fluorescence microscopy for caspase-3 activation, phosphatidylserine exposure and mitochondrial membrane depolarization. PBLs and fibroblasts from CADASIL patients showed a significantly higher response to dRib-induced apoptosis than those of controls. PBLs from CADASIL patients also showed a significantly higher percentage of apoptotic cells than PBLs from controls, even when cultured without dRib. The greater susceptibility of PBLs and fibroblasts from CADASIL patients to dRib-induced apoptosis suggests that NOTCH3 mutations are an important apoptotic trigger. Since PBLs from patients showed higher levels of apoptosis even in the absence of an apoptotic stimulus, cells from CADASIL patients appear to be physiologically prone to apoptotic cell death.