An overview of S100 proteins and their functions in skin homeostasis, interface dermatitis conditions and other skin pathologies.

S100 proteins comprise a family of structurally related proteins that are calcium-sensitive. S100 proteins have been found to play various roles in regulation of cell apoptosis, cell proliferation and differentiation, cell migration and invasion, energy metabolism, calcium homeostasis, protein phosphorylation, anti-microbial activity and inflammation in a variety of cell types. While the specific function of many S100 proteins remains unknown, some of the S100 proteins serve as disease biomarkers as well as possible therapeutic targets in skin diseases. Interface dermatitis (ID) is a histopathological term that covers many different skin conditions including cutaneous lupus erythematosus, lichen planus, and dermatomyositis. These pathologies share similar histological features, which include basal cell vacuolization and lymphocytic infiltration at the dermal-epidermal junction. In this review, we summarize how the S100 protein family contributes to both homeostatic and inflammatory processes in the skin. We also highlight the role of S100 proteins in neuronal signalling, describing how this might contribute to neuroimmune interactions in ID and other skin pathologies. Last, we discuss what is known about the S100 family proteins as both biomarkers and potential treatment targets in specific pathologies.

Special Considerations of Atopic Dermatitis in Skin of Color.

Atopic dermatitis (AD) is a chronic inflammatory skin condition with heterogeneous presentations and prevalence across different skin tones. In this chapter, AD is explored through the lens of racial and ethnic diversity, emphasizing the special considerations among patients with skin of color (SOC). Specific ethnic groups may exhibit unique AD phenotypes, and these differences pose unique diagnostic and management challenges, especially given the disproportionate impact of AD in African American and Asian populations due to environmental exposures and social factors (i.e., decreased access to healthcare resources). Addressing these social disparities, increasing representation in medical education and the clinical space, as well as ongoing research can help better serve this patient population.