Are Preferred Scalp Locations for Alopecia Areata Patches a Clue to Neuronal Etiology?

Efficacy, safety, and Pharmacoeconomics of Three Common Strategies for Pediatric Alopecia Areata Patients: A Retrospective Cohort Study

Objective

To evaluate and explore the efficacy, safety, and pharmacoeconomics of three common strategies for pediatric alopecia areata.

Methods

Chinese pediatric alopecia areata patients meeting the criteria were included and divided into three groups based on the received treatments. The efficacy, adverse events and pharmacoeconomics of these treatments were retrospectively analyzed.

Results

Twenty-four pediatric AA patients were recruited in this study. 100% (12/12) of patients from the traditional group achieved SALT100. In the tofacitinib group, 40.0% (2/5) of patients achieved SALT50. 20.0% (1/5) of patients achieved SALT75 and 40.0% (2/5) of patients achieved SALT100. In the MN group, 42.86% (3/7) of patients were non-responders. 14.28 (1/7) of patients achieved SALT75 and 42.86% (3/7) of patients achieved SALT100. The adverse effects (AEs) were mild in all three groups, and none of the patients discontinued the treatments due to the AEs. Comparing the other two groups, the MN treatment would be more time-intensive and more expensive.

Conclusion

For newly diagnosed or naive pediatric patients, the traditional treatment was the first-line approach. For long-duration, severe and refractory patients, tofacitinib and microneedling can be alternative options.

Immune-mediated alopecias and their mechanobiological aspects

Alopecia is a non-specific term for hair loss clinically diagnosed by the hair loss pattern and histological analysis of patient scalp biopsies. The immune-mediated alopecia subtypes, including alopecia areata, lichen planopilaris, frontal fibrosing alopecia, and central centrifugal cicatricial alopecia, are common, significant forms of alopecia subtypes. For example, alopecia areata is the most common autoimmune disease with a lifetime incidence of approximately 2% of the world's population. In this perspective, we discuss major results from studies of immune-mediated alopecia subtypes. These studies suggest the key event in disease onset as the collapse in immune privilege, which alters the hair follicle microenvironment, e.g., upregulation of major histocompatibility complex molecules and increase of cytokine production, and results in immune cell infiltration, inflammatory responses, and damage of hair follicles. We note that previous studies have established that the hair follicle has a complex mechanical microenvironment, which may regulate the function of not only tissue cells but also immune cell infiltrates. This suggests a potential for mechanobiology to contribute to alopecia research by adding new methods, new approaches, and new ways of thinking, which is missing in the existing literature. To fill this a gap in the alopecia research space, we develop a mechanobiological hypothesis that alterations in the hair follicle microenvironment, specifically in the mechanically responsive tissues and cells, partially due to loss of immune privilege, may be contributors to disease pathology. We further focus our discussion on the potential for applying mechanoimmunology to the study of T cell infiltrates in the hair follicle, as they are considered primary contributors to alopecia pathology. To establish the connection between the mechanoimmunological hypothesis and immune-mediated alopecia subtypes, we discuss what is known about the role of T cells in immune-mediated alopecia subtypes, using the most extensively studied AA as our model.

A "hair-raising" history of alopecia areata

A 3500-year-old papyrus from ancient Egypt provides a list of treatments for many diseases including "bite hair loss," most likely alopecia areata (AA). The treatment of AA remained largely unchanged for over 1500 years. In 30 CE, Celsus described AA presenting as scalp alopecia in spots or the "windings of a snake" and suggested treatment with caustic compounds and scarification. The first "modern" description of AA came in 1813, though treatment still largely employed caustic agents. From the mid-19th century onwards, various hypotheses of AA development were put forward including infectious microbes (1843), nerve defects (1858), physical trauma and psychological stress (1881), focal inflammation (1891), diseased teeth (1902), toxins (1912) and endocrine disorders (1913). The 1950s brought new treatment developments with the first use of corticosteroid compounds (1952), and the first suggestion that AA was an autoimmune disease (1958). Research progressively shifted towards identifying hair follicle-specific autoantibodies (1995). The potential role of lymphocytes in AA was made implicit with immunohistological studies (1980s). However, studies confirming their functional role were not published until the development of rodent models (1990s). Genetic studies, particularly genome-wide association studies, have now come to the forefront and open up a new era of AA investigation (2000s). Today, AA research is actively focused on genetics, the microbiome, dietary modulators, the role of atopy, immune cell types in AA pathogenesis, primary antigenic targets, mechanisms by which immune cells influence hair growth, and of course the development of new treatments based on these discoveries.