The polyphenol (−)-epigallocatechin-3-gallate prevents apoA-I_Iowa amyloidosis in vitro and protects human embryonic kidney 293 cells against amyloid cytotoxicity

Abstract

Introduction: Apolipoprotein A-I (apoA-I) amyloidosis is either a non-hereditary form with deposits of wild-type apoA-I proteins in atherosclerotic plaques or a hereditary form with progressive accumulation of mutant apoA-I proteins in different tissues. Several small polyphenolic molecules reportedly inhibited formation of fibrillar assemblies of some amyloidogenic proteins and their cytotoxicity, but small molecules that inhibit apoA-I fibril formation have never been reported.

Methods: Our methods included a thioflavin-T-binding assay, atomic force microscopy and dot blot and cell-based assays.

Results: We showed that (−)-epigallocatechin-3-gallate (EGCG), a tea-derived flavanol, inhibited in vitro fibril formation and disaggregated fibrils preformed by the N-terminal 1–83 fragments of wild-type (WT) apoA-I and the G26R point mutation of apoA-I (apoA-I_Iowa). We eliminated a common structure recognized by the anti-amyloid antibody OC by incubating apoA-I_Iowa with EGCG or treating apoA-I_Iowa fibrils with EGCG, which supported the above observation. In addition, EGCG rescued human embryonic kidney 293 cells from cytotoxicity and attenuated production of reactive oxygen species, which were induced by apoA-I_Iowa fibrils.

Conclusions: Our results support the concept that EGCG inhibits amyloid fibril formation of various amyloidogenic proteins. Thus, EGCG may be a candidate for providing a structure to develop de novo inhibitors for amyloidosis treatment.

• Amyloidosis
• apolipoprotein A-I
• EGCG
• oxidative stress
• recombinant amyloidogenic proteins

Acknowledgements

The authors would like to thank the Support Center for Advanced Medical Sciences, Institute of Biomedical Sciences, Tokushima University Graduate School.

Declaration of interest

The authors report no conflicts of interest. This work was partly supported by Grant-in-Aid for Scientific Research B-25293006 (to H. S.), Grant-in-Aid for Scientific Research C-23590448 and Grant-in-Aid for Challenging Exploratory Research 26670190 (to N. S.) and Grant-in-Aid for Young Scientists B-15K19488 (to K. N.) from the Japan Society for the Promotion of Science.