Chong Won Choi

Fatty acid-binding proteins (FABPs) are intracellular lipid chaperones that regulate gene expression by controlling lipid trafficking within subcellular organelles. Among them, FABP4 is primarily expressed in adipocytes and macrophages and has been implicated in inflammatory responses in adipose tissue; however, its role in skin inflammation remains poorly understood. Here, we investigated the immunomodulatory role of FABP4 using human psoriatic skin samples, single-cell RNA sequencing, and an imiquimod-induced mouse model of psoriasis. We further employed pharmacologic inhibition and genetic modulation of FABP4 to assess its effects on macrophage polarization, along with transcription factor regulon analyses to identify downstream regulatory mechanisms. FABP4 was highly expressed in macrophages infiltrating psoriatic skin, and in vivo pharmacological inhibition of FABP4 attenuated psoriasiform skin inflammation and shifted macrophage phenotypes, suppressing M1-associated features while promoting CD206-expressing alternatively activated macrophages. For mechanistic insights, we examined the regulon activity of transcription factors associated with macrophage polarization in psoriatic skin and identified an association between PPARG and macrophage polarization; our in vivo and in vitro experiments further demonstrated that FABP4 inhibition restored PPARG expression and activity in psoriasis mice, which was decreased by imiquimod application. Overall, our study demonstrated that FABP4 plays a critical role in skin inflammation by modulating macrophage polarization through PPARG regulation, suggesting that targeting FABP4 may represent a potential therapeutic strategy for psoriasis and other inflammatory skin diseases.

Long-term ketotifen use was associated with a significantly lower incidence of recorded diagnoses of benign cutaneous tumours among patients with neurofibromatosis type 1. No statistically significant association was observed for neural tumours. These findings suggest that ketotifen may be a potentially accessible adjunctive option in the management of benign cutaneous tumours in neurofibromatosis type 1.

Palmoplantar pustulosis (PPP) is a chronic relapsing inflammatory skin disorder predominantly affecting the palms and soles. Despite the continued use of oral systemic agents, real‐world data on their durability and treatment patterns in PPP remain limited. To investigate the treatment patterns, drug survival, and clinical factors associated with treatment persistence in patients with PPP receiving oral systemic therapies. We conducted a retrospective cohort study of patients diagnosed with PPP at a tertiary care referral center in Korea between January 2010 and August 2023. Patients were categorized according to the initial oral agent prescribed—cyclosporine, acitretin, or methotrexate. Treatment trajectories were assessed using predefined criteria, and 12‐month drug survival was evaluated. Clinical predictors of treatment non‐persistence were identified using Cox proportional hazards regression analysis. Among 374 patients, 192 received oral systemic therapy (cyclosporine, n = 110; acitretin, n = 72; methotrexate, n = 8). Cyclosporine was the most commonly prescribed first‐line agent. Median drug survival was the longest for cyclosporine, followed by methotrexate and acitretin ( p = 0.15). Nail involvement was associated with greater persistence (HR = 0.617; 95% CI: 0.444–0.857; p = 0.004), whereas baseline hypertension increased discontinuation risk (HR = 1.492; 95% CI: 1.015–2.195; p = 0.042). Discontinuation patterns differed by agent: cyclosporine was often stopped early due to adverse events but remained durable in patients who tolerated it; acitretin was associated with early and persistent adverse events, with well‐controlled disease emerging as a later reason for cessation; and methotrexate showed sustained use beyond 6 months, with most discontinuations attributed to well‐controlled disease. This study highlights the heterogeneous treatment trajectories and variable drug survival among oral agents for PPP. Nail involvement and hypertension may be key clinical predictors of persistence. These findings support individualized treatment approaches to improve long‐term management of PPP.

Sebum plays a critical role in maintaining skin homeostasis, but its overproduction is associated with pore enlargement, acne, and other dermatological conditions. Acne causes physiological stress and reduced quality of life, contributing to social burden. Although various sebaceous gland models exist, including 2D, explant‐based, and in vivo/ex vivo systems, each has limitations in longevity or physiological relevance. While in vitro 3D sebocyte models would be more suitable for screening, they still fall short in recapitulating interactions with key skin components like fibroblasts and keratinocytes. Here, a 3D skin model was developed to mimic the epidermis and dermal layer including sebaceous glands. Uniform 3D collagen‐based artificial sebaceous glands, termed SebaSpheres, were produced using microfluidic technology. These SebaSpheres successfully accumulated lipids and expressed the differentiation marker, Blimp‐1. SebaSpheres were integrated into the microwell‐shaped dermal layer populated with fibroblasts, followed by the addition of keratinocytes (HaCaT) to establish an epidermis of the skin model. During co‐culture, live/dead imaging indicated that all three cell types maintained viability. Involucrin expression was observed in HaCaT cells under co‐culture conditions, indicating compatibility with sebocyte integration. This in vitro skin model provides a platform for future studies aimed at evaluating acne‐related stimuli and cosmetic compounds targeting oily skin.

Objective: Given that the therapeutic evidence for doxycycline in rosacea has predominantly been derived from studies on papulopustular rosacea (PPR), this study aimed to evaluate the efficacy and safety of combined oral doxycycline, topical calcineurin inhibitor (TCI), and pulsed dye laser (PDL) therapy in erythematotelangiectatic rosacea (ETR) and to identify clinical predictors of treatment response. Materials and Methods: Medical photographs of patients with ETR treated with oral doxycycline, TCI, and two subsequent PDL sessions were retrospectively reviewed. Erythema on the right cheek was quantitatively measured using computer‐aided image analysis. Results: Of the 79 included patients, 47 had the ETR subtype and 32 had the mixed ETR/PPR subtype. Erythema significantly improved after oral doxycycline and TCI treatment ( p < 0.001) and further PDL treatment ( p < 0.001). Particularly, in patients with moderate‐to‐severe ETR, background erythema improved to a level comparable to that observed in patients with mild ETR after treatment ( p = 0.307). Post‐treatment erythema did not differ by age ( p = 0.963) or Fitzpatrick skin type ( p = 0.277); however, it was significantly lower among males ( p = 0.008) and in patients without prior steroid treatment ( p = 0.046). No serious adverse events, including photosensitivity, were observed. Conclusion: Combined oral doxycycline, TCI, and PDL therapy is effective and safe for ETR, especially in patients with higher severity. Prompt diagnosis and avoidance of steroid misuse may improve treatment responses.

Several dermatological comorbidities, including juvenile xanthogranuloma, cutaneous mastocytosis, trichotillomania, xanthelasma palpebrarum, lipoma and malignant melanoma, have been frequently observed in patients with neurofibromatosis type 1 in different age groups. Dermatologists, who are crucial in diagnosing and managing this disorder throughout a patient’s life, should be aware of these comorbidities.

Purpose: This review outlines recent advances in skin-on-a-chip (SoC) and skin-integrated multi-organ-on-a-chip (MOC) technologies, emphasizing their potential to enhance dermatological research and drug testing by mimicking human physiology.Current Concepts: SoCs integrate skin models into microfluidic systems with dynamic perfusion, thereby enabling more physiologically relevant skin responses. MOC platforms link skin models with organ models such as the liver or gut, allowing the study of systemic interactions, including drug metabolism, immune responses, and inflammation.Discussion and Conclusion: These microphysiological systems reproduce human physiology more closely than traditional models. Although technical challenges remain, ongoing development may significantly improve drug screening, disease modeling, and personalized dermatological applications.

Neurofibromatosis type 1 (NF1) affects multiple organs progressively, leading to a shortened life expectancy. This study aimed to identify the complications that are prominent in each age group by comparing 28,082 patients with NF1 and 84,246 matched controls. Benign and malignant neoplasms along with neurological complications were the primary contributors to hospital use across most age groups. Respiratory and circulatory disorders were a common cause of hospital use in children and older adults, respectively. Except for soft tissue and central nervous system-originated malignancies, which are well-established NF1-related tumours, the highest rate ratios (RR) of malignancies with statistical significance was observed in the adrenal gland (0–9 years, RR 50.67, 95% CI 6.74–380.76); female genital organs (10–14 years, RR 12.06, 95% CI 1.35–107.93); respiratory and intrathoracic organs (15–19 years, RR 15.10, 95% CI 1.76–129.22; 20–29 years, RR 7.59, 95% CI 2.94–19.56; ≥ 60 years, RR 1.38, 95% CI 1.18–1.61); lip, oral cavity, and pharynx (30–39 years, RR 6.11, 95% CI 1.53–24.42); and bone and articular cartilage (40–49 years, RR 3.06, 95% CI 1.37–6.81; 50–59 years, RR 4.73, 95% CI 2.35–9.50). Comorbidities and malignancies that predominantly affect patients vary by age group; physicians should be aware of the appropriate management strategies throughout their lifespan.

Bo Mi Kang, Eunyoung Seo, Jung Min Ahn, Bo Ri Kim, Gwanyoung Kim, Kyungmin Lee, Seunghyun Choi, Taeheon Kim, Yunjee Lee, Wonwoo Choi, Chong Won Choi, and Sang Woong Youn. Biomolecules & Therapeutics -0001;0:. https://doi.org/10.4062/biomolther.2024.210

This study presents the GMS chip, a microfluidic platform modeling gut–skin interactions via coculture of intestinal cells, skin cells, and gut microbiota, enabling research on microbiome effects and probiotic validation.