Nboost Doctor brochure - Flipbook - Page 13
What are the functions of the epidermis?
Protective barrier against mechanical and chemical injury 10
Keratinocytes are characterised by structural components acquired throughout the epidermal cell
differentiation process:
1. INTERCELLULAR JUNCTIONS – seal adjacent
keratinocytes
2. EXTRACELLULAR MATRIX – extracellular
environment to support cell adhesion,
intercellular communication and regulation
of cell differentiation
3. KERATIN CYTOSKELETON – internal structure
that confers keratinocytes high deformation
resistance 70 times more than other cells
Protection against mechanical and chemical
injury depends directly on the structural epidermal
integrity – a stratified arrangement of cell layers with
keratinocytes bonded by intercellular junctions and
extracellular matrixes.
A primary factor for preserving the skin barrier is
its capacity for cell renewal, which is affected by
keratinocyte’s differentiation and proliferation rate.
Maintenance of water-ion balance 6,11
The epidermis plays a fundamental role
in internal homeostasis by controlling the
exchange of substances, especially water
and ions, with the external environment.
The epidermis has multiple biochemical
components with selective properties to
preserve this functionality.
During keratinocyte migration towards the
most superficial layers, increased acidity
causes filaggrin to become degraded into
small, free metabolites and amino acids,
forming natural moisturising factors (NMF).
Normal
epidermis
Dry, brittle and
scaly epidermis
Attack from
external factors
Epidermal
layer
AQPs are essential for maintaining waterion balance of the cell by transporting
water and small molecules of solute across
epidermal cell membranes.
Skin surface
lipids
Increased
transepidermal
water loss
Immunological defense 12
Epidermal cells – including keratinocytes,
melanocytes, and Langerhans cells – can produce
multiple cytokines, reinforcing the epidermis as
a tissue that is immunocompetent and active in
creating an immunological barrier.
The epidermis has an active role in the inflammatory
response and in the preparation of more efficient
systemic immune responses with improved B- and
T-cell activation.
1. Blanpain C, Fuchs E. Epidermal homeostasis: a balancing act of stem cells in the skin. Nat Rev Mol Cell Biol. 2009 Mar;10(3):207-17 2. Nguyen AV, Soulika AM. The Dynamics
of the Skin’s Immune System. Int J Mol Sci. 2019;20(8):1811. 3. Russell-Goldman E, Murphy GF. The Pathobiology of Skin Ageing: New Insights into an Old Dilemma. Am J Pathol.
2020;190(7):1356-69. 4. Brenner M, Hearing VJ. The Protective Role of Melanin Against UV Damage in Human Skin. Photochem Photobiol. 2008;84(3):539-49. 5. Hara M, Verkman
AS. Glycerol replacement corrects defective skin hydration, elasticity, and barrier function in aquaporin-3-deficient mice. Proc Natl Acad Sci USA. 2003;100(12):7360-65.
6. Kezic, S., Kammeyer, A., Calkoen, F., Fluhr, J.W., Bos, J.D. Natural moisturizing factor components in the stratum corneum as biomarkers of filaggrin genotype: evaluation
of minimally invasive methods. Br. J. Dermatol. 2009; 161:1098–1104. 7. Farage MA, Miller KW, Elsner P, Maibach HI. Characteristics of the Ageing Skin.
Adv Wound Care (New Rochelle). 2013;2(1):5-10. 8. Lulevich V, Yang HY, Isseroff RR, Liu GY. Single cell mechanics of keratinocyte cells. Ultramicroscopy. 2010;110(12):1435-42.
9. Ortonne JP. Pigmentary changes of the ageing skin. Br J Dermatol. 1990;122(35):21-8. 10. Lulevich V, Yang HY, Isseroff RR, Liu GY. Single cell mechanics of keratinocyte cells.
Ultramicroscopy. 2010;110(12):1435-42. 11. Tzaphlidou, M. The role of collagen and elastin in aged skin: an image processing approach. Micron. 2004; 35:173–177.
12. Brazzini, B., Ghersetich, I., Hercogova, J., Lotti, T. The neuro-immuno- cutaneous-endocrine network: relationship between mind and skin. Dermatol. Ther. 2003;16: 123–131.
© Mine S, Fortunel NO, Pageon H, Asselineau D (2008) Ageing Alters Functionally Human Dermal Papillary Fibroblasts but Not Reticular Fibroblasts: A New View of Skin
Morphogenesis and Ageing. PLoS ONE 3(12): e4066. doi:10.1371/journal.pone.0004066
