Epidermal Barrier and its Functions in the Body Defense

Overview

Epidermal barrier represents one of the essential conditions of life on Earth. However, our present understandingof its function is still insufficient. The role of water incorporated in stratum corneum has not been yet studied enough.Till recently, both the stratum corneum et granulosum were considered to be „dead“ layers. It turned out that theselayers form very active part of epidermis and they have a secretory function. Their rigid anhydrotic consistency,complex intercellular spaces, and lipid bilayers produced by lamellar bodies form the defense barrier against boththe loss of fluids and ions and protecting against the hostile external environment. Important stabilizing function inthe barrier has ceramides and urea. The Langerhans’ dendritic cells and macrophages induce production of cytokinesin keratinocytes by means of calcium signals. That triggers the inflammatory cascade, which is accompanied byformation of pathological types of T-cells and by activation of apoptosis. Last but not least, the impairment ofepidermal barrier has an important role in the physiological aging of the skin.

Key words:
epidermal barrier, lipid bilayers, ceramides, dendritic cells, lamellar bodies, urea, atopy.