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Detection of alpha‐synuclein conformational variants from gastro‐intestinal biopsy tissue as a potential biomarker for Parkinson's disease
Author(s) -
Ruffmann C.,
BengoaVergniory N.,
Poggiolini I.,
Ritchie D.,
Hu M. T.,
AlegreAbarrategui J.,
Parkkinen L.
Publication year - 2018
Publication title -
neuropathology and applied neurobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.538
H-Index - 95
eISSN - 1365-2990
pISSN - 0305-1846
DOI - 10.1111/nan.12486
Subject(s) - biomarker , immunohistochemistry , pathology , western blot , staining , proximity ligation assay , biopsy , medicine , pathological , biology , receptor , biochemistry , gene
Aims Gastrointestinal ( GI ) α‐synuclein (aSyn) detection as a potential biomarker of Parkinson's disease ( PD ) is challenged by conflicting results of recent studies. To increase sensitivity and specificity, we applied three techniques to detect different conformations of aSyn in GI biopsies obtained from a longitudinal, clinically well‐characterized cohort of PD patients and healthy controls ( HC ). Methods With immunohistochemistry ( IHC ), we used antibodies reactive for total, phosphorylated and oligomeric aS yn; with aS yn proximity ligation assay ( AS ‐ PLA ), we targeted oligomeric aS yn species specifically; and with paraffin‐embedded tissue blot ( AS ‐ PET ‐blot) we aimed to detect fibrillary, synaptic aS yn. Results A total of 163 tissue blocks were collected from 51 PD patients (113 blocks) and 21 HC (50 blocks). In 31 PD patients, biopsies were taken before the PD diagnosis (Prodromal); while in 20 PD patients biopsies were obtained after diagnosis (Manifest). The majority of tissues blocks were from large intestine (62%), followed by small intestine (21%), stomach (10%) and oesophagus (7%). With IHC , four staining patterns were detected ( neuritic, ganglionic, epithelial and cellular ), while two distinct staining patterns were detected both with AS ‐ PLA ( cellular and diffuse signal) and with AS ‐ PET ‐blot ( aS yn‐localized and pericrypt signal). The level of agreement between different techniques was low and no single technique or staining pattern reliably distinguished PD patients (Prodromal or Manifest) from HC . Conclusions Our study suggests that detection of aS yn conformational variants currently considered pathological is not adequate for the diagnosis or prediction of PD . Future studies utilizing novel ultrasensitive amyloid aggregation assays may increase sensitivity and specificity.