The latest developments in cutaneous homeostasis

Abstract

Background: The skin is a major actor of human homeostasis mainly due to its important role in body temperature regulation but also through its role of barrier against any external aggression, and as a transmitter of a lot of information to the brain. It is very important that this vital organ can regulate its own homeostasis to be able to assume its role for the rest of human body. It is commonly admitted that cutaneous homeostasis is more or less the barrier effect but the last discovery for the last decade opens new interesting fields of investigation. Degradation of tight junctions with age are well-known. In rosacea, the water permeation in epidermis sever the cells and break the junctions, it is an open door for microbial infections and dramatic dryness. On atopic mice skin model, Yokushi and al. showed in 2015 that tight junctions of atopic skin are more permeable and this is correlated with the filaggrin protein depletion. If junctions still stop microbials and big molecules penetration, they let small molecules under 30 KDalton to penetrate the epidermis. This could be one of the causes of the inflammatory status of atopic skins and of dryness as water permeation is increased as well. Conclusions: In conclusion, skin homeostasis becomes more and more complex with the last discoveries about skin microbiota. Interactions between sebum, epidermal lipids, epidermal peptides and microbiota are huge. We have an open field to innovate in new treatment taking into account the capability of billions of living cells on our skin surface which talk with our cells all the time and work together to help our skin assume its defense role of the human body.