Gerstmann-Sträussler-Scheinker syndrome (GSS) is a hereditary neurodegenerative disease characterized by extracellular aggregations of pathological prion protein (PrP) forming characteristic plaques. Our study aimed to evaluate the micromorphology and protein composition of these plaques in relation to age, disease duration, and co-expression of other pathogenic proteins related to other neurodegenerations. Hippocampal regions of nine clinically, neuropathologically, and genetically confirmed GSS subjects were investigated using immunohistochemistry and multichannel confocal fluorescent microscopy. Most pathognomic prion protein plaques were small (2-10 µm), condensed, globous, and did not contain any of the other investigated proteinaceous components, particularly dystrophic neurites. Equally rare (in two cases out of nine) were plaques over 50 µm having predominantly fibrillar structure and exhibit the presence of dystrophic neuritic structures; in one case, the plaques also included bulbous dystrophic neurites. Co-expression with hyperphosphorylated protein tau protein or amyloid beta-peptide (Aβ) in GSS PrP plaques is generally a rare observation, even in cases with comorbid neuropathology. The dominant picture of the GSS brain is small, condensed plaques, often multicentric, while presence of dystrophic neuritic changes accumulating hyperphosphorylated protein tau or Aβ in the PrP plaques are rare and, thus, their presence probably constitutes a trivial observation without any relationship to GSS development and progression.

• Klíčová slova
• Gerstmann–Sträussler–Scheinker syndrome, PrP, co-expression, plaques,
• MeSH
• dospělí MeSH
• Gerstmannova-Strausslerova-Scheinkerova nemoc * genetika   metabolismus   patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• missense mutace * MeSH
• patologická konformace proteinů * genetika   metabolismus   patologie   MeSH
• prionová bílkovina * genetika   metabolismus   MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• srovnávací studie MeSH
• Názvy látek
• prionová bílkovina * MeSH

Alzheimer's disease (AD) is characterised by the accumulation of intracytoplasmic aggregates of tau protein, which are suggested to spread in a prion-like manner between interconnected brain regions. This spreading is mediated by the secretion and uptake of tau from the extracellular space or direct cell-to-cell transmission through cellular protrusions. The prion-like tau then converts the endogenous, normal tau into pathological forms, resulting in neurodegeneration. The endoplasmic reticulum/Golgi-independent tau secretion through unconventional secretory pathways involves delivering misfolded and aggregated tau to the plasma membrane and its release into the extracellular space by non-vesicular and vesicular mechanisms. Although cytoplasmic tau was thought to be released only from degenerating cells, studies now show that cells constitutively secrete tau at low levels under physiological conditions. The mechanisms of secretion of tau under physiological and pathological conditions remain unclear. Therefore, a better understanding of these pathways is essential for developing therapeutic approaches that can target prion-like tau forms to prevent neurodegeneration progression in AD. This review focuses on unconventional secretion pathways involved in the spread of tau pathology in AD and presents these pathways as prospective areas for future AD drug discovery and development.

• Klíčová slova
• Alzheimer's disease, Extracellular tau, Neurodegenerative diseases, Prion-like protein, Tau aggregation, Tau propagation, Tauopathies, Unconventional tau secretion,
• MeSH
• Alzheimerova nemoc metabolismus   patologie   MeSH
• lidé MeSH
• mezibuněčná komunikace fyziologie   MeSH
• mozek metabolismus   patologie   MeSH
• patologická konformace proteinů metabolismus   patologie   MeSH
• proteiny tau metabolismus   MeSH
• tauopatie metabolismus   patologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• MAPT protein, human MeSH Prohlížeč
• proteiny tau MeSH

Neuropathological diagnostic criteria of neurodegenerative disorders are based on the presence of specific inclusions in a specific area of brain tissue that correlate with clinical manifestations. Concomitant neurodegenerative disorders correspond to a combination of two (or more) different fully developed diseases in the same patient. Concomitant neurodegenerative pathology represents the presence of definite neurodegeneration and deposits of pathological proteins specific for another disease, which is not, however, fully developed. Very frequent overlaps include Alzheimer's disease and alpha-synuclein inclusions. Nevertheless, careful neuropathological investigations reveal an increasing frequency of different co-pathologies in examined brains. In Alzheimer's disease, protein TDP-43 may co-aggregate, but it is not clear whether this is atypical isolated Alzheimer's disease or overlap of Alzheimer's disease with early frontotemporal lobar degeneration. Comorbidities of Alzheimer's disease and tauopathies are relatively rare. A combination of vascular pathology with primary neurodegeneration (mostly Alzheimer's disease or dementia with Lewy bodies) is historically called mixed dementia. Overlap of different neuropathologically confirmed neurodegenerations could lead to atypical and unusual clinical presentations and may be responsible for faster disease progression. Several CSF biomarkers have been evaluated for their utility in diagnostic processes in different neurodegenerative dementias; however, evidence regarding their role in neurodegenerative overlaps is still limited.

• Klíčová slova
• Alzheimer's disease, Mixed dementia, Neurodegeneration, Synucleinopathy, TDP-43, Tauopathy,
• MeSH
• alfa-synuklein metabolismus   MeSH
• Alzheimerova nemoc metabolismus   patologie   MeSH
• biologické markery metabolismus   MeSH
• demence s Lewyho tělísky metabolismus   patologie   MeSH
• DNA vazebné proteiny metabolismus   MeSH
• lidé MeSH
• patologická konformace proteinů metabolismus   patologie   MeSH
• proteiny tau metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• alfa-synuklein MeSH
• biologické markery MeSH
• DNA vazebné proteiny MeSH
• proteiny tau MeSH
• SNCA protein, human MeSH Prohlížeč
• TARDBP protein, human MeSH Prohlížeč