Da	Dalton
kDa	kilo Dalton
g	gram
kg	kilogram
L	Liter
mol	mole
mg	milligram
ppm	parts per million
μg	microgram
μmol	micro mole
μM	micro molar
3H	radioactive hydrogen (tritium)
14C	radioactive carbon 14
5α-DHT	5α-dihydrotestosterone
5α-Reductase	Steroid enzyme that converts testosterone into 5α-DHT
AD	Atopic dermatitis
Akt	Protein kinase B (a serine/threonine-specific protein kinase)
ALA	Alanine
α-MSH	α-melanocyte stimulating hormone
AMP	Antimicrobial peptides
AP-1	Activator protein 1
ATP	adenosine triphosphate
BPH	Benign prostatic hyperplasia
COX	Cyclo-oxygenase
DNA	Deoxyribonucleic acid
EGF	Epidermal growth factor
ERβ	Estrogen receptor β
FGF	Fibroblast growth factor
GI	Gastrointestinal tract
G2	Gap 2 phase (cell cycle)
Glc-Cer	Glucosylceramide
Gly	Glycine
GPX	Glutathione peroxidase
HaCaT	Human keratinoctyes
Hyp	Hydroxy proline
HMP	Human microbiome project
HDL	High-density lipoprotein
HO-1	Heme oxygenase 1
IL	interleukins
IgA, IgG, IgM	Immunoglobulin A, G, or M
IGF	Insulin-like growth factor
KOD	36. amino acid synthetic collagen. The sequence of the peptide is (Pro-Lys-Gly) (Pro-Hyp-Gly) (Asp-Hyp-Gly), and in single-letter amino acid abbreviation is (P-K-G); (P-O-G) (D-O-G), giving it the name KOD
LC	Langerhans cells
LDL	Low-density lipoproteins
MCH	Major histocompatibility complex
MDA	Malondialdehyde
MMP	Matrix metalloproteinases
NF-κB	Nuclear factor κ-light-chain-enhancer of activated B cells
Na2SeO3	Sodium selenite
Nrf2	Nuclear factor (erythroid-derived 2)-like 2 (basic leucine zipper)
PDGF	Platelet derived-growth factor
Pro	Proline
PRR	Pattern recognition receptor
RDA	Recommended dietary allowance
SEPW1	Seleno-protein 1
RNA	Ribonucleic acid
ROS	Reactive oxygen species (oxidative stress)
RSSC	Residual skin surface components
SeMet	Seleno-L-methionine
Ser	Serine
SIRT	NAD-dependent deacetylase sirtuin-1
TEWL	Trans-epidermal water loss
TGF	Transforming growth factor
Th17	Helper T cell 17
TMP	Tissue inhibitor of matrix metalloproteinases
TLR	Toll-like receptors
TNF-α	Tumor necrosis factor α
T-reg	Regulator T cells
US	United States
USA	United States of America
USFDA	United States Federal Drug Administration
UV	Ultraviolet
ZIP2	Zinc transporter-2