Identification of Human Hair Follicle Antigens Targeted in the Presumptive Autoimmune Hair Follicle Disorder Alopecia Areata and Their Potential Functional Relevance In Vitro: Methods Development for Isolation and Identification of Alopecia Areata-Relevant Human Hair Follicle Antigens Using a Proteomics Approach and Their Functional Assessment Using an Ex Vivo Hair Follicle Organ Culture Model

This study investigated the autoimmune basis of alopecia areata (AA) by identifying hair follicle antigens targeted by the immune system. Using serum antibodies from 10 AA patients and 10 controls, researchers identified trichohyalin and keratin 16 as potential target antigens through mass spectrometry. Trichohyalin was immunoprecipitated by all AA sera but only by 5 normal sera, with significantly higher Mascot scores in the AA group (p=0.005). Functional studies showed that antibodies to these proteins inhibited hair fiber elongation in ex vivo hair follicle cultures. Indirect immunofluorescence revealed higher immunoreactivity in AA sera against anagen hair follicles, particularly in the outer and inner root sheaths. The findings suggested that antibodies against anagen-specific hair follicle antigens might play a pathogenic role in AA.