Skincare and LPS

(2) Skin Immunity and LPS

The skin in contact with the outside world might as well be called an immune organ, as with the intestinal tract. Being an organ most directly exposed to stimulations from the outside world, the skin utilizes the immune system to maintain homeostasis. Therefore, all the various cells present in the skin have potential for immune responses. Immune responses based on information exchanged between these skin cells maintain skin health.

The beauty of the skin and immunity are closely related. The immune system removes old cells and waste products; also helps to generate new cells; heals the skin damaged by ultraviolet rays, heat, or physical force; and rejects pathogenic bacteria invading through wounds. In other words, skin immunity enhances the skin’s clarity, promotes skin cell turnover, and heals the skin.

By the way, LPS works on skin immunity.

Since the LPS molecule contains a lipid that has an affinity for sebum, it penetrates the sebum-containing stratum corneum. However, as described earlier, the granular layer beneath the stratum corneum contains “tight junction” that prevent most substances from passing through. LPS is believed to be no exception and cannot penetrate the tight junction. However, LPS receptors are present in keratinocytes, found most commonly in the epidermis; Langerhans cells, whose dendrites extend to the stratum corneum; and regulatory T (Treg) cells, which mediate inflammation in a suppressive manner. Therefore, all these cell types respond to LPS. Thus, even if LPS does not penetrate the “tight junction”, it can work on the skin immune system.