Early Microglial Activation Precedes Neuronal Loss in the Brain of the Cstb−/− Mouse Model of Progressive Myoclonus Epilepsy, EPM1

• Published in: Journal of neuropathology and experimental neurology Vol. 71; no. 1; pp. 40 - 53
• Main Authors: Tegelberg, Saara, Kopra, Outi, Joensuu, Tarja, Cooper, Jonathan D, Lehesjoki, Anna-Elina
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD American Association of Neuropathologists, Inc 01.01.2012; Lippincott Williams & Wilkins
• Subjects: Alcoholism and acute alcohol poisoning; Animals; Biological and medical sciences; Brain; Cell Death - genetics; Cerebral Cortex - metabolism; Cerebral Cortex - pathology; Cystatin B - deficiency; Cystatin B - genetics; Disease Models, Animal; Male; Medical sciences; Mice; Mice, Knockout; Microglia - metabolism; Microglia - pathology; Neurology; Neurons - metabolism; Neurons - pathology; Time Factors; Toxicology; Unverricht-Lundborg Syndrome - genetics; Unverricht-Lundborg Syndrome - metabolism; Unverricht-Lundborg Syndrome - pathology; Cerebellum; Animal model; Cerebral cortex; Neuroglia; Epilepsy; Central nervous system; Activation; Involuntary movement; Encephalon; Posterior thalamic nuclei; Somatosensory cortex; Neurodegeneration; Cerebrum; Neurological disorder; Nervous system diseases; Myoclonus; Rodentia; Astrocyte; Cerebral disorder; Microglia; Vertebrata; Mammalia; Mouse; Astrocyte activation; Central nervous system disease; Early; Myoclonus epilepsy
• ISSN: 0022-3069; 1554-6578
• DOI: 10.1097/NEN.0b013e31823e68e1

ABSTRACTProgressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1) is a hereditary neurodegenerative disorder caused by mutations in the cystatin B (CSTB) gene encoding an inhibitor of cysteine proteases. Here, we provide the first detailed description of the onset and progression of pathologic changes in the CNS of Cstb-deficient (Cstb) mice. Our data reveal early and localized glial activation in brain regions where neuron loss subsequently occurs. These changes are most pronounced in the thalamocortical system, with neuron loss occurring first within the cortex and only subsequently in the corresponding thalamic relay nucleus. Microglial activation precedes the emergence of myoclonia and is followed by successive astrocytosis and selective neuron loss. Neuron loss was not detected in thalamic relay nuclei that displayed no glial activation. Microglia showed morphologic changes during disease progression from that of phagocytic brain macrophages in young animals to having thickened branched processes in older animals. These novel data on the timing ofpathologic events in the CSTB-deficient brain highlight the potentialrole of glial activation at the initial stages of the disease. Determiningthe precise sequence of the neurodegenerative events in Cstb mouse brains will lay the basis for understanding the pathophysiology of EPM1.