Pathophysiology of Atopic Dermatitis in Different Ethnic Groups

Atopic dermatitis (AD) is a common chronic inflammatory skin disease with high prevalence worldwide, including countries from Asia, Africa and Latin America, and in different ethnic groups. In recent years, more attention on AD heterogeneity associated on multiple factors, including patient’s ethnic background, has been posed, resulting in an increasing body of clinical, genetic, epidemiologic, and immune-phenotypic evidence that delineate differences among racial groups with AD. 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, while very rarely in Africans. The Th2 activation 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 own a strong Th2/Th22 signature and the absence of Th1/Th17 skewing. In addition, the ethnic heterogeneity may own important therapeutic implications as the 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 the investigation about safety and efficacy across different ethnicities. The purpose of this review is to describe the heterogeneity of pathophysiology across ethnicities and its potential therapeutic implications.