What’s new in hair — September 2017 | Dr. Yuval Ramot
Secretory phospholipase A2-IIA overexpressing mice exhibit cyclic alopecia mediated through aberrant hair shaft differentiation and impaired wound healing response
Sci Rep. 2017 Sep 14;7(1):11619. doi: 10.1038/s41598-017-11830-9.
Secretory phospholipase A2 group IIA (sPLA2-IIA) is expressed in the skin, and serves as an EGF signalling modulator. It has a role in lipid metabolism and possesses a growth promoting activity. In this study, Chovatiya et al. checked the effect of K14-sPLA2-IIA expression in homozygous mice on hair growth. The mice experienced hair loss, that was accompanied by increased proliferation and differentiation of the hair follicle stem cells. This results in the development of cyclic alopecia at an early age due to the exhaustion of the hair follicle stem cells, also leads to impaired healing response. Taken together, this study highlights sPLA2-IIA as a therapeutic target for the treatment of alopecia and inflammatory conditions.
Shedding light on alopecia areata in pediatrics: A retrospective analysis of comorbidities in children in the national alopecia areata registry
Pediatr Dermatol. 2017 Sep;34(5):e271-e272. doi: 10.1111/pde.13238.
It has been reported in the past that alopecia areata (AA) is associated with several comorbidities. To further explore the associated comorbidities in the pediatric population, Sorrell et al. performed a retrospective study using data from the National Alopecia Areata Registry, including patients 13 years of age and younger at enrolment. They show that atopic dermatitis is more prevalent in patients with a more severe disease. Autoimmune comorbidities were also more prevalent in patients with AA, but in this case, there was no connection with the severity of AA, except for vitiligo. The authors conclude that there should be a high index of suspicion for autoimmune conditions in younger patients with AA.
Efficacy of topical tofacitinib in promoting hair growth in non-scarring alopecia: possible mechanism via VEGF induction
Arch Dermatol Res. 2017 Sep 7. doi: 10.1007/s00403-017-1777-5. [Epub ahead of print]
Tofacitinib has recently shown promise in treating alopecia areata in humans. However, the fact that there is a more rapid transition to anagen and activation of hair follicle progenitor cells with tofactinib suggests that it can also be valuable in the treatment of other forms of non-scarring alopecia. Therefore, Meephansan et al. performed a study to evaluate the effect of topical tofacitinib on hair growth in C57BL/6 mice in comparison to minoxidil and vehicle. They show that tofacitinib led to early onset hair growth, more hair growth and the fastest rate of hair growth in comparison to minoxidil and vehicle. The mechanism behind these effects are still not entirely clear, but the authors of the study demonstrated that there was less inflammatory cell infiltration after tofactinib treatment and a higher expression of VEGF. Based on these findings, the authors conclude that tofacitinib should be further studied to eventually be applied in human clinical trials.
Mol Cell Endocrinol. 2017 Sep 11. pii: S0303-7207(17)30492-6. doi: 10.1016/j.mce.2017.09.009. [Epub ahead of print]
Androgens are known to have an important role in skin and hair physiology, and they also participate in different pathologies of the hair and skin. In this comprehensive review, Ceruti et al. describe the physiological role of androgens in the skin and hair, with special emphasize on the androgen receptor and its functions. A large part of the review is dedicated to the role of the androgen receptor and its connection with androgenetic alopecia. This part of the article is an important update on the knowledge acquired in this field, with a detailed review of the connection between androgens and the Wnt/β-catenin signalling in androgenetic alopecia. Such better understanding of the molecular pathways involved in androgenetic alopecia and their connection to the androgen receptor has paved the way for new treatment possibilities.
NF-κB participates in mouse hair cycle control and plays distinct roles in the various pelage hair follicle types
J Invest Dermatol. 2017 Sep 20. pii: S0022-202X(17)32963-9. doi: 10.1016/j.jid.2017.08.042. [Epub ahead of print]
NF-κB activity has been shown to be important for hair follicle (HF) development. However, recent data suggest that it might also have a crucial role during HF cycle. To examine this question, Krieger et al. used a NF-κB reporter mouse, and showed that there is an excess activation of NF-κB in key locations of the HF, specifically in the secondary hair germ, inner root sheath and hair bulb, suggesting that NF-κB takes part in anagen induction. The authors then used mice with doxycycline-inducible NF-κB suppression in the epithelium to further explore the role NF-κB in the hair cycle of the different pelage HF types. This method showed that NF-κB is needed for guard HF cycling and induces anagen and growth of zigzag and awl HFs. The authors conclude that these findings support previous hypothesis that there is a big similarity between the signalling pathways that are activated in HF morphogenesis during embryogenesis and the pathways that are activated during hair cycle progression and anagen development.
JAMA Dermatol. Published online September 27, 2017. doi:10.1001/jamadermatol.2017.3694
Many studies have suggested that alopecia areata (AA) is associated with additional autoimmune conditions, and especially thyroid disorders and vitiligo (as has also been shown in the Pediatr Dermatol paper reviewed in this column). In this study, Patel et al. examined the results of thyroid function tests in 298 AA patients younger than 21 years in the aim of establishing clinical factors that can guide thyroid function screening. Twenty percent of the patients had abnormalities in thyroid testing, mostly hypothyroidism due to Hashimoto’s thyroiditis. Based on further sub-analysis of the results, the authors conclude that routine thyroid function testing should be performed in AA children who have a personal history of atopy, clinical findings suggestive for thyroid disease, Down syndrome or a family history of thyroid disease.