Particulate matter (PM) is known to have harmful effects on human health. Epidemiological studies have suggested that PM exposure is related to skin diseases and extrinsic skin ageing. However, the mechanisms by which PM affects skin are unclear. The aim of this study was to investigate the mechanism of action of PMs on epidermal inflammation and skin ageing using a co‐culture of human keratinocytes (HaCaT) and fibroblasts (HDF). SRM 1648a (pmA) and 1649b (pmB), which mainly comprise heavy metals and polycyclic aromatic hydrocarbons, respectively, were used as reference PMs. Cytotoxic effects, activation of AhR, phosphorylation of p38 kinase and ROS generation were examined in PM‐treated HaCaT cells. The phosphorylation of p38 MAPK induced by PMs was shown to be critically important for the increases in IL‐1α and IL‐1β expression. Moreover, the mRNA and protein expression levels of MMP1 and COX2 were markedly increased in HDF cells co‐cultured with PM‐treated HaCaT cells. In conclusion, PMs induce the expression of pro‐inflammatory cytokines in keratinocytes via the p38 MAPK pathway, and these interleukins increase the expression of MMP1 and COX2 in HDF cells. These results suggest that PMs trigger skin ageing via p38 MAPK activation and interleukin secretion in epidermal keratinocytes.

Background: There are few pharmacologic options to reduce erythema and flushing in patients with recalcitrant erythematotelangiectatic rosacea (ETR). We previously reported two cases of refractory flushing and erythema of rosacea that were successfully treated with intradermal botulinum toxin injection, and additional research is needed to prove the efficacy and safety of this treatment. Objective: To report the efficacy and safety of botulinum toxin injection as an aid in persistent erythema of rosacea patients. Methods: A total of 20 Korean patients with recalcitrant ETR were enrolled to receive treatment by injection of botulinum toxin. Patients received one treatment of intradermal botulinum toxin injection and were assessed 1, 2, 4, and 8 weeks after treatment. The severity of erythema and telangiectasia was investigated by a non-treating physician, and the Erythema Index (EI) was assessed by mexameter at each visit. Patient satisfaction and any adverse events were also assessed at each visit. Results: 17 patients completed all follow-up visits and were included in the analysis. Intradermal injection of botulinum toxin significantly reduced erythema severity and EI in ETR patients. Patients reported a satisfaction score of 2.94±0.56 at 8 weeks after treatment. Except for three patients who discontinued the study early due to inconvenience of facial muscle paralysis, 17 patients participating in the final analysis did not report side effects except injection pain at the time of the procedure. Conclusion: Intradermal injection of botulinum toxin can be used as an effective and relatively safe adjuvant agent for recalcitrant and persistent erythema of ETR patients. (Ann Dermatol 30(6) 688∼693, 2018

BACKGROUND A wide lower face and a square jaw are considered esthetic problems, particularly in Asia. OBJECTIVE To investigate the optimal dose of a novel botulinum toxin (prabotulinum toxin A) for treating masseteric hypertrophy. METHODS Ninety subjects with masseteric hypertrophy were randomly divided into 5 groups and treated with placebo (A, normal saline) or prabotulinum toxin A (B: 24, C: 48, D: 72, and E: 96 units). Photography, ultrasonography, and 3-dimensional imaging were performed before and after injection at baseline and at 4, 8, 12, and 16 weeks after treatment. The participants also rated their satisfaction. RESULTS Masseter thickness significantly reduced in all groups at 12 weeks, compared with that in the placebo group. A dose-dependent reduction in masseter thickness was observed at the resting and maximal clenching positions. Sonography and 3-dimensional imaging revealed a gradual reduction in masseter thickness and volume, respectively, during the first 12 weeks. Despite being slightly effective, a dose of 24 units might be insufficient for resolving square face problems. Patients in Group E reported discomfort during jaw movement. CONCLUSION Prabotulinum toxin A could effectively improve lower face contour without major complications, with an optimal dose of 48 to 72 units, followed by reinjection after 12 weeks.

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A botulinum toxin (BTX) injection can be a simple and safe alternative to calf reduction surgery or liposuction without interrupting daily life. However, its optimum dosage and clinical response are not yet well known. A total of 40 patients with bilateral gastrocnemius muscle hypertrophy were enrolled in this study. All volunteers were randomly categorized into four groups and then administered different amounts of BTX (160 U and 200 U) on the medial and lateral aspects of their calves. All subjects showed clinical improvement with a reduction in the gastrocnemius muscle size after BTX injection. However, our results showed that the decrease in leg circumference was not dose dependent. No side effects of the injections, such as weakness of the legs, deformity, or abnormal sensation, were observed. There were also no cases of swelling, edema, hematoma, or infection. BTX at both dosages can be safely and effectively applied for calf muscle contouring without disturbing gait during walking or running.