Successful hair regrowth in an acute diffuse form of alopecia areata during oral tacrolimus treatment in a patient with rheumatoid arthritis

Impact of Rheumatoid Arthritis on Alopecia: A Nationwide Population-Based Cohort Study in Taiwan

Objectives: Studies on the relationship between rheumatoid arthritis (RA) and alopecia areata (AA) are limited. This study investigated the effect of RA on alopecia areata risk in a nationwide cohort study. Methods: We analyzed 2000-2012 data from the Longitudinal Health Insurance Database in Taiwan. The follow-up period was extended up to the end of 2013. We defined RA as a diagnosis using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code 714.0 during at least three outpatient visits or one admission and the use of disease-modifying antirheumatic drugs (DMARDs) for >30 days. The enrollees with AA were identified using the ICD-9-CM code 704.01. We enrolled a comparison cohort comprising participants randomly matched by age and sex, with the same index date as that of the study cohort. Furthermore, we investigated alopecia risk by using Cox proportional-hazards regression models after propensity score matching for sex, age, comorbidities, and medication use. Results: In total, 2,905 patients with RA (74% women, mean age: 51.9 years) and 2,905 controls were followed for 22,276 and 25,732 person-years, respectively. Alopecia risk was 2.64-fold (95% confidence interval = 1.47-4.76) higher in patients with RA than in patients without RA after age, sex, comorbidities, and medication use were adjusted for. In addition, patients with thyroid disease presented considerable alopecia risk. Patients with RA in the younger age group (20-40 years) had the highest alopecia risk. Conclusions: Alopecia risk is significantly higher in patients with RA than in those without RA, particularly in the younger age group (20-40 years). RA assessment should be considered when examining patients with alopecia, especially young adults.

Frontiers in alopecia areata pathobiology research

This current review explores selected and as yet insufficiently investigated frontiers in current alopecia areata (AA) pathobiology research, with an emphasis on potential "new" players in AA pathobiology that deserve more systematic exploration and therapeutic targeting. Indeed, new evidence suggests that CD8⁺ T cells, which have long been thought to be the central players in AA pathobiology, are not the only drivers of disease. Instead, subsets of natural killer (NK) and so-called "unconventional" T cells (invariant NK T cells, γδ T cells, classic NK cells, and type 1 innate lymphoid cells), all of which can produce large amounts of IFN-γ, might also drive AA pathobiology independent of classical, autoantigen-dependent CD8⁺ T-cell functions. Another important new frontier is the role of regulatory lymphocyte subsets, such as regulatory T cells, γδ regulatory T cells, NKT10 cells, and perifollicular mast cells, in maintaining physiologic hair follicle immune privilege (IP); the extent to which these functions are defective in patients with AA; and how this IP-protective role could be restored therapeutically in patients with established AA. Broadening our AA research horizon along the lines suggested above promises not only to open the door to innovative and even more effective immunotherapy strategies for AA but will also likely be relevant for other autoimmune disorders in which pathobiology, ectopic MHC class I expression, and IP collapse play an important role.