Skin Immune Landscape: Inside and Outside the Organism

Abstract

The skin is an essential organ to the human body protecting it from external aggressions and pathogens. Over the years, the skin was proven to have a crucial immunological role, not only being a passive protective barrier but a network of effector cells and molecular mediators that constitute a highly sophisticated compound known as the “skin immune system” (SIS). Studies of skin immune sentinels provided essential insights of a complex and dynamic immunity, which was achieved through interaction between the external and internal cutaneous compartments. In fact, the skin surface is cohabited by microorganisms recognized as skin microbiota that live in complete harmony with the immune sentinels and contribute to the epithelial barrier reinforcement. However, under stress, the symbiotic relationship changes into a dysbiotic one resulting in skin disorders. Hence, the skin microbiota may have either positive or negative influence on the immune system. This review aims at providing basic background information on the cutaneous immune system from major cellular and molecular players and the impact of its microbiota on the well-coordinated immune responses in host defense.

Daily very low UV dose exposure enhances adaptive immunity, compared with a single high‐dose exposure. Consequences for the control of a skin infection

“…In 1978, Streilein defined the skin‐associated lymphoid tissue as an integrated system in which Langerhans cells, keratinocytes, resident epidermal cells, migrating lymphocytes and draining lymph nodes all work together coordinately to provide the skin with immune protection . Since then, the skin has been considered an immune organ and plenty of research has been performed in the field . Based on our previous results comparing shUVd and rlUVd effects on skin innate immune system, we decided to study if these changes can also modulate the adaptive immune response.…”

“…25,26 Since then, the skin has been considered an immune organ and plenty of research has been performed in the field. 27,28 Based on our previous results comparing shUVd and rlUVd effects on skin innate immune system, 16 we decided to study if these changes can also modulate the adaptive immune response.…”

Unbalanced Sphingolipid Metabolism and Its Implications for the Pathogenesis of Psoriasis

“…The prefix sphingo-was used to express properties similar to the sphinx of this mysterious class of lipids. The most important function assigned to SLs is that they act as second messengers in many biological processes [45].…”

Nanodermatology‐based solutions for psoriasis: State‐of‐the art and future prospects

“…This system is known as “skin immune system” or SIS. Skin also guests skin‐associated lymphoid tissues (SALTs), that has the function to process and present skin antigens to lymph nodes (Abdallah, Mijouin, & Pichon, ; Bragazzi, Orsi, Ansaldi, Gasparini, & Icardi, ; Casey, ; Dragicevic & Maibach, ; Oláh, Szöllősi, & Bíró, ; Park & Kim, ; Yazdi, Röcken, & Ghoreschi, ). A clear understanding of SIS and SALTs is of crucial importance for a proper understanding of the mechanisms of intra‐dermal (ID) vaccination and related immunization practices, as well as of the response to nanotherapeutic agents (Bragazzi et al, ).…”