CLINICAL AND BIOCHEMICAL FEATURES OF ENDOTHELIAL DYSFUNCTION AND BLOOD–BRAIN BARRIER IMPAIRMENT IN CHILDREN WITH PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY.

Progressive multifocal leukoencephalopathy (PML) in children is a severe neurodemyelinating disease associated with pronounced neuroinflammatory and neurovascular disorders. The aim of the study was to assess the clinical and biochemical features of endothelial dysfunction and blood-brain barrier impairment in pediatric PML. Children aged 3 to 18 years with confirmed PML were examined. Comprehensive assessment included clinical neurological status, neuroimaging, laboratory, and biochemical parameters. The level of circulating endothelial cells was determined using flow cytometry. A significant increase in circulating endothelial cells was detected in patients with PML, correlating with the severity of neurological deficit and the extent of demyelinating changes on MRI. The findings indicate an important role of endothelial dysfunction and blood-brain barrier impairment in the pathogenesis of the disease. Circulating endothelial cells may serve as promising biomarkers for disease activity, early diagnosis of neurovascular disorders, and monitoring of pathogenetic therapy effectiveness.