Distribution Patterns of Astrocyte Populations in the Human Cortex.

Astrocytes are a major class of glial cell in the central nervous system that have a diverse range of types and functions thought to be based on their anatomical location, morphology and cellular properties. Recent studies highlight that astrocyte dysfunction contributes to the pathogenesis of neurological conditions. However, few studies have described the pattern, distribution and density of astrocytes in the adult human cortex. This study mapped the distribution and density of astrocytes immunolabelled with a range of cytoskeletal and membrane markers in the human frontal cortex. Distinct and overlapping astrocyte populations were determined. The frontal cortex from ten normal control cases (75 ± 9 years) was immunostained with glial fibrillary acidic protein (GFAP), aldehyde dehydrogenase-1 L1 (ALDH1L1), connexin-43 (Cx43), aquaporin-4 (AQP4), and glutamate transporter 1 (GLT-1). All markers labelled populations of astrocytes in the grey and white matter, separate cortical layers, subpial and perivascular regions. All markers were informative for labelling different cellular properties and cellular compartments of astrocytes. ALDH1L1 labelled the largest population of astrocytes, and Cx43-immunopositive astrocytes were found in all cortical layers. AQP4 and GLT-1 labelled distal astrocytic process and end-feet in the same population of astrocytes (98% of GLT-1-immunopositive astrocytes contained AQP4). In contrast, GFAP, the most widely used marker, predominantly labelled astrocytes in superficial cortical layers. This study highlights the diversity of astrocytes in the human cortex, providing a reference map of the distribution of distinct and overlapping astrocyte populations which can be used for comparative purposes in various disease, inflammatory and injury states involving astrocytes.

Coexisting Lewy body disease and clinical parkinsonism in amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is associated with a range of clinical phenotypes and shows progressive degeneration of upper and/or lower motor neurons, and phosphorylated 43 kDa TAR DNA-binding protein (pTDP-43) inclusions in motor and non-motor pathways. Parkinsonian features have been reported in up to 30% of ALS patients, and Lewy bodies, normally associated with Lewy body disease (LBD), have been reported in a small number of ALS cases, with unknown clinical relevance. This study investigates the prevalence of clinically relevant LBD in a prospectively studied ALS cohort to determine whether concomitant pathology contributes to the clinical heterogeneity. METHODS: All ALS cases held by the New South Wales Brain Bank (n = 97) were screened for coexisting LBD consistent with clinical disease (Braak ≥ stage IV). Relevant clinical and genetic associations were determined. RESULTS: Six cases had coexisting LBD Braak ≥ stage IV pathology. The age at symptom onset (69 ± 7 years) and disease duration (4 ± 3 years) in ALS cases with coexisting LBD did not differ from ALS cases. Three patients had lower limb onset and two patients had bulbar onset. Two patients developed the clinical features of Parkinson's disease, with one receiving a dual diagnosis. All cases had no known relevant family history or genetic abnormalities. CONCLUSION: The prevalence of clinically relevant LBD pathology in ALS is higher than in the general population, and has implications for clinical and neuropathological diagnoses and the identification of biomarkers.