Skin aging is a complex process influenced by intrinsic and extrinsic factors. Together, these factors affect the structure and function of the epidermis and dermis. Histologically, aging skin typically shows epidermal atrophy due to decreased cell numbers. The dermis of aged skin shows decreased numbers of mast cells and fibroblasts. Fibroblast senescence contributes to skin aging by secreting a senescence-associated secretory phenotype, which decreases proliferation by impairing the release of essential growth factors and enhancing degradation of the extracellular matrix through activation of matrix metalloproteinases (MMPs). Several molecular mechanisms affect skin aging including telomere shortening, oxidative stress and MMP, cytokines, autophagic control, microRNAs, and the microbiome. Accumulating evidence on the molecular mechanisms of skin aging has provided clinicians with a wide range of therapeutic targets for treating aging skin.

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.

Purpose Migraine is a relatively common neurologic disorder. A possible link between atopic disorders and migraine has been suggested. This study investigated atopic disorders and their risks of migraine in the Korean population. Methods From the Korean National Health Insurance Service database, patients aged ≥ 20 years who underwent health screening between January and December of 2009 were enrolled. To evaluate the risk of migraine, Cox proportional hazards regression analyses were performed. Results In multivariable analysis, the atopic dermatitis group (adjusted hazard ratio [aHR], 1.28; 95% confidence interval [CI], 1.23–1.33), asthma group (aHR, 1.32; 95% CI, 1.30–1.34) and allergic rhinitis group (aHR, 1.45; 95% CI, 1.44–1.46) had significantly increased risks of migraine compared to their respective control groups ( P < 0.001). The patients with 1 (aHR, 1.43; 95% CI, 1.42–1.44), 2 (aHR, 1.50; 95% CI, 1.47–1.53), and 3 (aHR, 1.64; 95% CI, 1.43–1.88) atopic disorders had significantly increased risks of migraine compared to the control group ( P < 0.001). Conclusions Our results demonstrate that patients with atopic disorders may have increased risk of migraine and that the larger the number of concomitant atopic disorders, the higher the risk of migraine.

Background High‐intensity focused ultrasound (HIFU) has been recently introduced as a non‐invasive therapeutic modality for controlling excessive subcutaneous fat. Objective The efficacy and safety of the HIFU device for sculpting the abdomen, upper arm, and thigh were evaluated. Materials and Methods Ten subjects with more than 10 mm of subcutaneous fat in the abdomen, upper arm, and/or thigh were recruited. We evaluate mean change in the thickness and circumference of subcutaneous fat of each treated area measured using ultrasound 12 weeks after the procedure, the degree of pain, and subject and practitioner satisfaction 12 weeks after the procedure. Results The mean change of subcutaneous fat thickness in the abdomen, upper arm, and thigh measured using ultrasound 12 weeks after the procedure was −4.33 ± 2.42, −1.86 ± 1.35, and −1.86 ± 1.35 mm, respectively. Compared with pretreatment, subcutaneous fat thickness of the abdomen and upper arm was significantly reduced (p = 0.0020 and p = 0.0004, respectively), but not in the thigh (p = 0.0716). Highest patient satisfaction was for the abdomen. Pain was generally tolerable. Conclusion The results from the present study indicate HIFU can be an effective and safe therapeutic modality for removing excessive subcutaneous fat in humans.