The pathological process amyloidosis, in which misfolded proteins (amyloids) form insoluble fibril deposits, occurs in many diseases, including Alzheimer’s disease (AD) and type 2 diabetes mellitus (T2D). However, little is known about whether different forms of amyloid proteins interact or how amyloid formation begins in vivo. A new study published in The American Journal of Pathology has found evidence that amyloid from the brain can stimulate the growth of fibrils in the murine pancreas and pancreatic-related amyloid can be found along with brain-related amyloid in human brain senile plaques. Islet amyloid can be found in islets of Langerhans (photo) in almost all patients with T2D. Islet amyloid is made up of islet amyloid polypeptide (IAPP), which is derived from its precursor proIAPP. Accumulation of IAPP can lead to beta-cell death. In the brain, deposits of beta-amyloid in the cortex and blood vessels are characteristic findings in AD. Several clinical studies have shown that patients with T2D have almost a two-fold greater risk of developing AD. The data described in the current study suggest that one link between the two diseases may be the processes underlying amyloidosis. This investigation focused on understanding how amyloid deposits "seed" or spread within a tissue or from one organ to another. "Several soluble proteins are amyloid-forming in humans. Independent of protein origin, the fibrils produced are morphologically similar," said Gunilla T. Westermark, Ph.D, Department of Medical Cell Biology at Uppsala University in Sweden. "There is a potential for structures with amyloid-seeding ability to induce both homologous and heterologous fibril growth.
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