Amyloid : the international journal of experimental and clinical investigation : the official journal of the International Society of Amyloidosis
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Amyloidosis is a disease group caused by pathological aggregation and deposition of peptides in diverse tissue sites. Apart from the fibril protein, amyloid deposits frequently enclose non-fibrillar constituents. In routine diagnostics, we noticed the presence of complement 9 (C9) in amyloid. ⋯ No data were found regarding caspase 3. Our findings demonstrate the ubiquitous, spatial and specific enrichment of C9 in amyloid deposits irrespective of amyloid-, organ- or tissue type. Our findings lend support to the hypothesis that amyloidosis might activate the complement cascade, which could lead to the formation of the membrane attack complex and cell death.
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More than 30 proteins and peptides have been found to form amyloid fibrils in human diseases. Fibrils formed by transthyretin (TTR) are associated with ATTR amyloidosis, affecting many vital organs, including the heart and peripheral nervous system. Congo red staining is the gold standard method for detection of amyloid deposits in tissue. ⋯ Using this method, we achieved sensitive detection of monomeric TTR in a microplate immunoassay and immunofluorescence labelling of ex vivo tissue from two patients containing ATTR aggregates. The system's utility was confirmed on sections from a patient with AA amyloidosis and liver sections from inflamed mouse. These results suggest that the detection system constitutes important new technology for highly sensitive detection of microscopic amounts of ATTR amyloid deposited in tissue.