Angiogenesis, the growth of new blood vessels from preexisting vessels, is associated with inflammation in various pathological conditions. Well-known angiogenetic factors include vascular endothelial growth factor (VEGF), angiopoietins, platelet-derived growth factor, transforming growth factor-β, and basic fibroblast growth factor. Yes-associated protein 1 (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) have recently been added to an important angiogenic factor. Accumulating evidence indicates associations between angiogenesis and chronic inflammatory skin diseases. Angiogenesis is deeply involved in the pathogenesis of psoriasis. VEGF, angiopoietins, tumor necrosis factor-a, interleukin-8, and interleukin-17 are unregulated in psoriasis and induce angiogenesis. Angiogenesis may be involved in the pathogenesis of atopic dermatitis, and in particular, mast cells are a major source of VEGF expression. Angiogenesis is an essential process in rosacea, which is induced by LL-37 from a signal cascade by microorganisms, VEGF, and MMP-3 from mast cells. In addition, angiogenesis by increased VEGF has been reported in chronic urticaria and hidradenitis suppurativa. The finding that VEGF is expressed in inflammatory skin lesions indicates that inhibition of angiogenesis is a useful strategy for treatment of chronic, inflammatory skin disorders.

Human skin is the largest organ and serves as the first line of defense against environmental factors. The human microbiota is defined as the total microbial community that coexists in the human body, while the microbiome refers to the collective genome of these microorganisms. Skin microbes do not simply reside on the skin but interact with the skin in a variety of ways, significantly affecting the skin barrier function. Here, we discuss recent insights into the symbiotic relationships between the microbiome and the skin barrier in physical, chemical, and innate/adaptive immunological ways. We discuss the gut-skin axis that affects skin barrier function. Finally, we examine the effects of microbiome dysbiosis on skin barrier function and the role of these effects in inflammatory skin diseases, such as acne, atopic dermatitis, and psoriasis. Microbiome cosmetics can help restore skin barrier function and improve these diseases.

Brimonidine is a highly selective α2-adrenergic receptor agonist approved by the FDA for the treatment of rosacea. Rosacea is a major clinical disease with vasodilatation and rash on the centre of the face, and that brimonidine as a vasoconstrictor can act as a remedy for rosacea. However, there is no study of how brimonidine has an effect on rosacea-related immune cells or mechanisms in the skin to improve rosacea. In this study, we observed that clinical features of rosacea induced by LL-37 in Balb/c mice were improved after the application of brimonidine gel, and we also showed a marked decrease in the number of inflammatory cells, especially mast cells (MCs) histologically. Furthermore, we confirmed that mRnA levels of MC enzymes increased by LL-37 were reduced by brimonidine gel. To our knowledge, we first found that brimonidine has a mechanism of treating rosacea by reducing the number and mRnA levels of MC-specific enzymes, an important immune cell in the pathogenesis of rosacea. | BACKGROUNDRosacea is a common chronic inflammatory skin disease characterized by telangiectasia and flushing.[1] The erythema of rosacea is thought to result from abnormal cutaneous vasomotor activity in the central part of the face. Brimonidine tartrate 0.33% gel (Mirvaso gel; Galderma, Lausanne, Switzerland), a highly selective α2-adrenergic receptor agonist, was recently recommended for the treatment of persistent facial erythema in patients with rosacea due to its potent vasoconstrictive effects. [2] Several clinical studies have demonstrated that brimonidine rapidly improves facial flushing and erythema. [2,3] However, the molecular and histological effects of brimonidine on rosacea remain largely unknown. Although the vasoconstrictive property of brimonidine gel has been suggested to contribute to the therapeutic effect, it was assumed that not only contracting the expanded blood vessels would act on the therapeutic mechanism. | QUESTION ADDRESSEDThe aims of this study were to investigate the histological changes and gene expression levels in rosacea-like skin lesions when applied with brimonidine and to identify the role of brimonidine gel in the pathogenesis of rosacea. In this study, we investigated whether brimonidine gel could influence the number of mast cells (MCs) and mRnA levels of tryptase and chymase by evaluating the response of topical application of brimonidine gel to rosacea-like skin lesions in mice. | EXPERIMENTAL DESIGNThirty-five 7-week-old female Balb/c mice were used in this study (Dooyeol Biotech, Seoul, Korea). The experimental protocol was approved by the Animal Care Committee of Catholic University of Korea. The mice were divided into three groups: control (n=11), LL-37 (n=12), and LL-37 plus brimonidine (LL-37+ brimonidine; n=12). The mice in the LL-37 and LL-37+ brimonidine groups had LL-37 injected intradermally into shaved back skin to induce rosacea-like skin lesions.Immediately after the injection of LL-37 (40 μL), the mice in the LL-37+ brimonidine group had brimonidine tartrate 0.3...