Overview of Atopic Dermatitis in Different Ethnic Groups

Abstract

Atopic dermatitis (AD) is a common chronic inflammatory skin disease with a high prevalence worldwide, including countries from Asia, Africa, and Latin America, and in different ethnic groups. In recent years, more attention has been placed on the heterogeneity of AD associated with multiple factors, including a patient's ethnic background, resulting in an increasing body of clinical, genetic, epidemiologic, and immune-phenotypic evidence that delineates differences in AD among racial groups. Filaggrin (FLG) mutations, the strongest genetic risk factor for the development of AD, are detected in up to 50% of European and 27% of Asian AD patients, but very rarely in Africans. Th2 hyperactivation is a common attribute of all ethnic groups, though the Asian endotype of AD is also characterized by an increased Th17-mediated signal, whereas African Americans show a strong Th2/Th22 signature and an absence of Th1/Th17 skewing. In addition, the ethnic heterogeneity of AD may hold important therapeutic implications as a patient's genetic predisposition may affect treatment response and, thereby, a tailored strategy that better targets the dominant immunologic pathways in each ethnic subgroup may be envisaged. Nevertheless, white patients with AD represent the largest ethnicity enrolled and tested in clinical trials and the most treated in a real-world setting, limiting investigations about safety and efficacy across different ethnicities. The purpose of this review is to describe the heterogeneity in the pathophysiology of AD across ethnicities and its potential therapeutic implications.

Keywords: allergy; atopic eczema; cellular; dermatitis; epidemiology; ethnic differences; immunological; itch; molecular; physiological therapeutic; prevention; skin disease; treatment.

Figure 1

Main genetic, clinical, and immunological features in AD patients across ethnicities. Predominant genetic features of each subgroup, immune-polarization, and potential therapeutic implications are shown. FLG: Filaggrin; LOF: Loss-of-function; IL: Interleukin; TSLP: Thymic stromal lymphopoietin; IRF2: Interferon regulatory factor 2; TLR2: Toll-like receptor 2; FCER1A: Fcε Receptor1α; DEFB1: B -Defensin 1; SPINK5: Serine Peptidase Inhibitor Kazal Type 5; TCHH: Trichohyalin; TCHHL1: Trichohyalin like 1; CRNN: Cornulin; HRNR: Hornerin; CLDN1: Claudin 1; Th: T helper; JAKi: JAK inhibitors. Created with BioRender.com.