Epigallocatechin-3-Gallate as a Potential Therapeutic Drug for TTR-Related Amyloidosis: “In Vivo” Evidence from FAP Mice Models

Nelson Ferreira,Maria Rosário Almeida,Maria João Saraiva,Sergio T Ferreira

doi:10.1371/journal.pone.0029933

Nelson Ferreira, Maria Rosário Almeida + Show 2 more

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https://doi.org/10.1371/journal.pone.0029933

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Journal: PloS one	Publication Date: Jan 10, 2012
Citations: 130	License type: CC BY 4.0

Affiliation: University of Porto

Abstract

BackgroundFamilial amyloidotic polyneuropathy (FAP) is a neurodegenerative disease caused by the extracellular deposition of mutant transthyretin (TTR), with special involvement of the peripheral nervous system (PNS). Currently, hepatic transplantation is considered the most efficient therapy to halt the progression of clinical symptoms in FAP since more than 95% of TTR is produced by the liver. However, less invasive and more reliable therapeutic approaches have been proposed for FAP therapy, namely based on drugs acting as inhibitors of amyloid formation or as amyloid disruptors. We have recently reported that epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea, is able to inhibit TTR aggregation and fibril formation, “in vitro” and in a cellular system, and is also able to disrupt pre-formed amyloid fibrils “in vitro”.Methodology and Principal FindingsIn the present study, we assessed the effect of EGCG subchronic administration on TTR amyloidogenesis “in vivo”, using well characterized animal models for FAP. Semiquantitative immunohistochemistry (SQ-IHC) and Western blot analysis of mice tissues after treatment demonstrated that EGCG inhibits TTR toxic aggregates deposition in about 50% along the gastrointestinal tract (GI) and peripheral nervous system (PNS). Moreover EGCG treatment considerably lowered levels of several biomarkers associated with non-fibrillar TTR deposition, namely endoplasmic reticulum (ER)-stress, protein oxidation and apoptosis markers. Treatment of old FAP mice with EGCG resulted not only in the decrease of non-fibrillar TTR deposition but also in disaggregation of amyloid deposits. Consistently, matrix metalloproteinase (MMP)-9 and serum amyloid P component (SAP), both markers of amyloid deposition, were also found reduced in treated old FAP mice.Conclusions and SignificanceThe dual effect of EGCG both as TTR aggregation inhibitor and amyloid fibril disruptor together with the high tolerability and low toxicity of EGCG in humans, point towards the potential use of this compound, or optimized derivatives, in the treatment of TTR-related amyloidoses.

Highlights

Familial amyloidotic polyneuropathy (FAP) is an autosomal dominant hereditary disease characterized by the extracellular deposition of nonbranching cross b-pleated sheet fibrils in the connective tissue, with a special involvement of the peripheral nervous system (PNS), both autonomic and motor
Based in previous ‘‘in vitro’’ studies indicating that EGCG inhibits TTR amyloid fibril formation [8,9,10] we decided to test its effect ‘‘in vivo’’ using FAP mice models
EGCG dosage was selected based upon available ‘‘in vivo’’ reports [17], and taking into account both its oral acute (LD50 = 2170 mg/kg) and subchronic toxicity [18]. This dosage did not produce adverse side effects, as no significant difference was observed in body weight, behavior or mortality between animals treated with EGCG and age matched untreated controls

Summary

Introduction

Familial amyloidotic polyneuropathy (FAP) is an autosomal dominant hereditary disease characterized by the extracellular deposition of nonbranching cross b-pleated sheet fibrils in the connective tissue, with a special involvement of the peripheral nervous system (PNS), both autonomic and motor. More than one hundred amyloidogenic mutations have been reported, presenting some clinical heterogeneity but typically with peripheral nervous system (PNS) involvement [2]. The precise molecular mechanisms underlying TTR fibrillogenesis have not been yet fully disclosed, it is widely accepted that this process involves TTR tetramer dissociation, leading to partially unfolded monomers which self-assemble originating non-fibrillar aggregates, protofibrils and mature amyloid fibrils [3,4]. Familial amyloidotic polyneuropathy (FAP) is a neurodegenerative disease caused by the extracellular deposition of mutant transthyretin (TTR), with special involvement of the peripheral nervous system (PNS). We have recently reported that epigallocatechin-3-gallate (EGCG), the most abundant catechin in green tea, is able to inhibit TTR aggregation and fibril formation, ‘‘in vitro’’ and in a cellular system, and is able to disrupt pre-formed amyloid fibrils ‘‘in vitro’’

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