Changes in the Morphology, Number, and Protein Levels of Plasma Exosomes in CADASIL Patients

Update on the Epidemiology, Pathogenesis, and Biomarkers of Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common monogenic disorder of the cerebral small blood vessels. It is caused by mutations in the NOTCH3 gene on chromosome 19, and more than 280 distinct pathogenic mutations have been reported to date. CADASIL was once considered a very rare disease with an estimated prevalence of 1.3-4.1 per 100,000 adults. However, recent large-scale genomic studies have revealed a high prevalence of pathogenic NOTCH3 variants among the general population, with the highest risk being among Asians. The disease severity and age at onset vary significantly even among individuals who carry the same NOTCH3 mutations. It is still unclear whether a significant genotype-phenotype correlation is present in CADASIL. The accumulation of granular osmiophilic material in the vasculature is a characteristic feature of CADASIL. However, the exact pathogenesis of CADASIL remains largely unclear despite various laboratory and clinical observations being made. Major hypotheses proposed so far have included aberrant NOTCH3 signaling, toxic aggregation, and abnormal matrisomes. Several characteristic features have been observed in the brain magnetic resonance images of patients with CADASIL, including subcortical lacunar lesions and white matter hyperintensities in the anterior temporal lobe or external capsule, which were useful in differentiating CADASIL from sporadic stroke in patients. The number of lacunes and the degree of brain atrophy were useful in predicting the clinical outcomes of patients with CADASIL. Several promising blood biomarkers have also recently been discovered for CADASIL, which require further research for validation.

Determination of Blood NOTCH3 Extracellular Domain and Jagged-1 Levels in Healthy Subjects

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common genetic disorder among those responsible for hereditary strokes, and it is caused by a mutation in the NOTCH3 gene on chromosome 19. Blood biomarkers related to the Notch signaling pathway have not been investigated extensively in CADASIL. In this study, we measured the serum and plasma levels of NOTCH3 extracellular domain (N3ECD) and its ligand, Jagged-1, in 279 healthy subjects. The levels of N3ECD and Jagged-1 showed significant correlations in both serum (p < 0.0001, r = 0.2681) and plasma (p < 0.0001, r = 0.4065). The N3ECD levels were significantly higher in the serum than in plasma and tend to increase with age. In contrast, there was no significant difference between the serum and plasma levels of Jagged-1 levels. To summarize, we were able to measure N3ECD and Jagged-1 protein levels in healthy human serum and plasma. Taken together, our findings provide the basis for further studies investigating the clinical use of blood N3ECD and Jagged-1 levels for CADASIL and other Notch signaling-related diseases.