Lifestyle Factors Involved in the Pathogenesis of Alopecia Areata

Abstract

Alopecia areata is a representative inflammatory skin disease that is associated with various environmental stimuli. While psychological stress is believed to be a major pathogenetic trigger in alopecia areata, infants and newborns also suffer from the disease, suggesting the possible presence of other environmental factors. Daily lifestyle is well known to be involved in various inflammatory diseases and influences the severity of inflammatory skin diseases. However, only a limited number of studies have summarized these influences on alopecia areata. In this review article, we summarize lifestyle factor-related influences on the pathogenesis of alopecia areata and focus on environmental factors, such as smoking, alcohol consumption, sleep, obesity, fatty acids, and gluten consumption.

Keywords: Th1; Th17; Th2; alopecia areata; lifestyle factors.

Figure 1

Hair follicle structure and regulatory mechanisms of immune reaction related to lifestyle factors.

Figure 2

Immunological regulators in the hair follicle associated with alopecia areata. There are immune response suppressors in hair follicles, such as MHC class I/II, β2 macroglobulin, MIF, CD200, and PD-L1. These immunosuppressive factors are downregulated in hair follicles of patients with alopecia areata. On the other hand, trichohyalin and tyrosine-related protein 2 are known as immune response activators in hair follicles and are also related to the pathogenesis of alopecia areata.