By Sally Durant for Vitality Magazine – PART ONE
Traditional teaching on the epidermis tells us that it is a dead, keratinised tissue with little functionality other than to provide a toughened and largely impenetrable outer layer for the skin. In reality, this vastly undermines the importance of this tissue which creates an intricate structural and physiological defence mechanism.
The Natural Barrier Function of the skin (NBF) is a physical and chemical entity which not only protects the skin from the external environment but equally preserves the homeostasis, or wellbeing, within the deeper skin layers.
As a result it is hugely impactful to overall skin health and its compromisation will inevitably lead to varying degrees of skin dysfunction and disease. Recognising poor barrier function is therefore essential to the accurate assessment and effective treatment of the skin, but the subtle indications are not always easy to spot. Accurate analysis of the NBF requires advanced visual skills together with an in-depth understanding of the anatomy and physiology of the epidermal tissue and the extrinsic and intrinsic influences on its integrity.
Taking the physical defence barrier first, the bilayer formation of the flattened keratinocytes ‘sandwiched’ between the epidermal lipids create a cohesive and hydrophobic ‘wall’ – the cells and oils forming the bricks and mortar respectively. The epidermal lipids are produced by keratinocyte cells within the Prickle Cell Layer and are composed of Free Fatty Acids, Cholesterol and Ceramides, the source of which comes from the diet.
For this reason, if a client’s intake of the right fats and oils is low then you can expect the skin to be lacking intercellular lipids. Poor lipidity will in turn lead to a breaking up of the NBF, potentially allowing irritants and micro-organisms to enter the skin causing it to become over reactivewith sensations of stinging and burning while also being be prone to ageing oxidative stress. Furthermore, the entry of infection-causing micro-organisms will be more likely and Trans Epidermal Water Loss (TEWL) will add dehydration to the cocktail of skin imbalances.
This epidermal dehydration compounds the compromisation of the NBF by causing the reduction of natural desquamation essential to the normal eco- environment of the skin. A lack of water in the epidermis prevents the dissolution of the corneodesmosomes which are small protein filaments holding the epidermal cells together. This results in hyperkeratosis and subsequent further disorientation of the NBF.
The chemical barrier function is now also compromised. An imbalance in the oil and water content of the epidermal tissue subsequently impacts on the acidity of the skin leading to an increased susceptibility to infection and inflammation. This naturally is a key issue in all skins but perhaps most pertinent in oily or acne prone and rosacea skins, underlining the need for individuals with these conditions to ensure not only proper hydration but also a well supported intercellular lipidity. For many acne sufferers this will be a hard concept to grasp and so the need to educate clients in the difference between acne related sebum and the intercellular epidermal lipids is paramount.
With the sebum in mind, changes in its composition instigated by the acne cycle, comedogenesis and the activities of the p.acnes bacteria will of course have a significant effect on the chemical NBF. While the physiology of acne is too large a subject for study here, essentially the alteration in the percentage of Triglycerides and Free Fatty Acids in the sebum dramatically alter the pH of the skin surface. This leads to greater risk of inflammation and infection within the pilo-sebaceous unit and potentially spreading into the sebaceous gland and extra cellular matrix of the dermis
Recognising and treating poor barrier function requires an ‘inside out’ approach. While close visual examination is essential, the more subtle indications of impaired barrier function will require a comprehensive investigation into the client’s general health, lifestyle, diet and environment together with their history of clinical skin treatment and the products used at home. In the next edition of Vitality magazine, we will examine the process of assessing the NBF and how to correct its dysfunction to ensure you are addressing this essential element of skin health.