The transthyretin amyloidoses (ATTR) are devastating diseases characterized by progressive neuropathy and/or cardiomyopathy for which novel therapeutic strategies are needed. We have recently shown that curcumin (diferuloylmethane), the major bioactive polyphenol of turmeric, strongly suppresses TTR fibril formation in vitro, either by stabilization of TTR tetramer or by generating nonfibrillar small intermediates that are innocuous to cultured neuronal cells. In the present study, we aim to assess the effect of curcumin on TTR amyloidogenesis in vivo, using a well characterized mouse model for familial amyloidotic polyneuropathy (FAP). Mice were given 2% (w/w) dietary curcumin or control diet for a six week period. Curcumin supplementation resulted in micromolar steady-state levels in plasma as determined by LC/MS/MS. We show that curcumin binds selectively to the TTR thyroxine-binding sites of the tetramer over all the other plasma proteins. The effect on plasma TTR stability was determined by isoelectric focusing (IEF) and curcumin was found to significantly increase TTR tetramer resistance to dissociation. Most importantly, immunohistochemistry (IHC) analysis of mice tissues demonstrated that curcumin reduced TTR load in as much as 70% and lowered cytotoxicity associated with TTR aggregation by decreasing activation of death receptor Fas/CD95, endoplasmic reticulum (ER) chaperone BiP and 3-nitrotyrosine in tissues. Taken together, our results highlight the potential use of curcumin as a lead molecule for the prevention and treatment of TTR amyloidosis.

Tauroursodeoxycholic acid (TUDCA) is a unique natural compound that acts as a potent anti-apoptotic and anti-oxidant agent, reducing cytotoxicity in several neurodegenerative diseases. Since oxidative stress, apoptosis and inflammation are associated with transthyretin (TTR) deposition in Familial Amyloidotic Polyneuropathy (FAP), we investigated the possible TUDCA therapeutical application in this disease. We show by semi-quantitative immunohistochemistry and western blotting that administration of TUDCA to a transgenic mouse model of FAP decreased apoptotic and oxidative biomarkers usually associated with TTR deposition, namely the ER stress markers BiP and eIF2alpha, the Fas death receptor and oxidation products such as 3-nitrotyrosine. Most important, TUDCA treatment significantly reduced TTR toxic aggregates in as much as 75%. Since TUDCA has no effect on TTR aggregation "in vitro", this finding points for the "in vivo" modulation of TTR aggregation by cellular responses, such as by oxidative stress, ER stress and apoptosis and prompts for the use of this safe drug in prophylactic and therapeutic measures in FAP.