Research efforts across different disciplines are beginning to uncover biological factors that underlie racial differences in health status and disease severity. One common condition with a prevalence of 7.3 percent among U.S. adults is atopic dermatitis. In terms of prevalence and disease severity, African Americans are disproportionately affected when compared to European Americans.
Atopic dermatitis (AD) is a chronic skin disorder characterized by intense itching, very dry skin, eczematous lesions, and immune-mediated skin inflammation characterized by T and dendritic cell skin infiltration. Results of a recent study conducted at the Icahn School of Medicine at Mount Sinai Medical Center showed marked differences in the skin of those with AD compared to those who do not have the condition. Interestingly, differences were also found between African Americans, who have a more severe inflammatory response, and European Americans.
Biopsied skin samples from patients with and without AD were studied using immunohistochemistry and RNA-Seq (validated using quantitative RT-PCR). Dendritic cells marked by IgE receptors were significantly increased in skin lesions of African Americans with AD compared to that of European Americans with AD. However, langerin+ langerhans cells (dendritic cells specific for the epidermis) were increased only in African American lesions. Differences between African Americans and European Americans in the expression of T helper cell markers were also observed. Th1 and Th17 markers were more upregulated in lesions of European Americans compared to those of African Americans.
Differences in disease severity corresponded to serum IgE levels and expression of TH17 cytokines in African American patients. The increased infiltration of IgE-marked dendritic cells in lesions from African Americans corresponded with higher serum IgE and increased disease severity. The results discussed demonstrate the racial differences in molecular and cellular parameters associated with AD and the importance of a racially diverse patient population for clinical research. The data also provides crucial genetic and phenotypic information for application to personalized and precision medicine efforts and can support the development of more effective therapies across racial groups.