title: Dietary silk protein, sericin, improves epidermal hydration with increased levels of filaggrins and free amino acids in NC/Nga mice.
abstract: Epidermal hydration is maintained primarily by natural moisturising factors (NMF), of which free amino acids (AA) are major constituents that are generated by filaggrin degradation. To identify dietary sources that may improve skin dryness of atopic dermatitis (AD), we investigated dietary effects of silk proteins, sericin and fibroin, on epidermal levels of hydration, filaggrins and free AA, as well as PPARγ, peptidylarginine deiminase-3 (PAD3) and caspase-14 proteins involved in filaggrin expression and degradation processes. NC/Nga mice, an animal model of AD, were fed a control diet (group CA: atopic control) or diets with 1 % sericin (group S) or fibroin (group F) for 10 weeks. In group S, epidermal levels of hydration, total filaggrins and total free AA, as well as PPARγ, PAD3 and caspase-14, which were reduced in group CA, were increased to higher or similar levels of a normal control group of BALB/c mice (group C). Furthermore, profilaggrin, a precursor with multiple filaggrin repeats, and three repeat intermediates were increased, while two repeat intermediates and filaggrin were decreased in parallel with increased levels of glutamate and serine, major AA of NMF in group S. Despite increased levels of total filaggrins, total free AA, PPARγ and PAD3, epidermal levels of hydration, glutamate, serine and caspase-14 were not increased, but other minor AA of NMF were highly detected in group F. Dietary sericin improves epidermal hydration in parallel with enhancing profilaggrin expression and degradation into free AA that is coupled with elevated levels of PPARγ, PAD3 and caspase-14 proteins.
authors.affiliation: Department of Medical Nutrition, Graduate School of East-West Medical Science, Kyung Hee University, Yongin-si, Gyeonggi-do              446-701, Republic of Korea.
authors.forename: Hyunae
authors.initials: H
authors.lastname: Kim
authors.forename: Yu-ji
authors.initials: YJ
authors.lastname: Lim
authors.forename: Ji-Ho
authors.initials: JH
authors.lastname: Park
authors.forename: Yunhi
authors.initials: Y
authors.lastname: Cho
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D053456:Caspase 14 / Q000235:genetics / Q000378:metabolism; D003876:Dermatitis, Atopic / Q000188:drug therapy / Q000503:physiopathology; D004032:Diet; D019587:Dietary Supplements; D004817:Epidermis / Q000187:drug effects*; D000091344:Filaggrin Proteins; D005786:Gene Expression Regulation; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism; D055103:Hypodermoclysis; D007381:Intermediate Filament Proteins / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D047495:PPAR gamma / Q000235:genetics / Q000378:metabolism; D000076342:Protein-Arginine Deiminases; D047030:Sericins / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D047495:PPAR gamma; D047030:Sericins; D006867:Hydrolases; D053456:Caspase 14; D000076342:Protein-Arginine Deiminases