What’s new in hair — March 2016 | Dr. Yuval Ramot
A genome-wide association scan in admixed Latin Americans identifies loci influencing facial and scalp hair features.
Nat Commun. 2016 Mar 1;7:10815. doi: 10.1038/ncomms10815
The search for finding the elements that are responsible for the great variety that exists in human hair morphology is a long and tedious one. While genome-wide association scan is a very useful tool for identifying such elements, it necessitates a large number of samples from different ethnicities. In this study, Adhikari et al. performed a genome-wide association scan in over 6,000 individuals of mixed European, Native American and African ancestry. Eighteen association signals were identified, 10 of them are new. Of note, the authors found a genome-wide significant association for hair greying to a SNP located in the interferon regulatory factor 4 gene (IRF4), thus becoming the first reported locus for hair greying. Additionally, a genome-wide significant association for scalp hair shape was found to a SNP in PRSS53, which is expressed in high amounts in the inner root sheath, a segment of the hair follicle that is well-known to control hair structure and shape. These are obviously only the first steps in elucidating the factors that contribute to large variety of hair phenotypes that exist in the human population, but there is hope that with additional large studies like that one, our understanding will be expanded.
Cell Cycle. 2016 Mar 3:0. [Epub ahead of print]
An interesting question in hair research is whether aged hair follicles can be rejuvenated. In order to answer this question, Cao et al. have performed an elegant experiment, in which they transplanted young and old hair follicles into young and old nude mice. They showed that the growth of both young and old hair follicles was promoted when transplanted into young mice. This effect was not achieved when the hair follicles were transplanted into old mice. This finding was suggested to be related, at least in part, to an effect on nestin-expressing hair follicle-associated pluripotent stem cells. Taken together, this study suggests that hair loss associated with aging can be potentially reversed.
Alopecia areata: Animal models illuminate autoimmune pathogenesis and novel immunotherapeutic strategies
Autoimmun Rev. 2016 Mar 10. pii: S1568-9972(16)30056-8. doi: 10.1016/j.autrev.2016.03.008. [Epub ahead of print]
Animal models have played for years a major role in understanding mechanistic pathways of diseases, and are crucial for testing the efficacy of different treatments. Finding a proper animal model for alopecia areata (AA) has been a challenge for hair and autoimmune research. Nevertheless, luckily, in recent years there is growing number of options for using murine models for AA. In this article, Gilhar et al. review the available animal models, with emphasis on the two most eminent models in this field: the C3H/HeJ inbred mouse model and the humanized mouse model. These two models are reviewed in detail, and the advantages and disadvantages of each model are described. The authors conclude that these two models are mutually complementary, and researchers should be aware of their limitations when using them for conducting experiments. This article is a welcome addition to the literature on AA, addressing an important aspect of AA research.
Low circulating insulin-like growth factor-1 and high density lipoprotein are associated with hair loss in middle-aged women
Br J Dermatol. 2016 Mar 9. doi: 10.1111/bjd.14529.
While several studies have shown in the past association between female pattern hair loss (FPHL) and several other disorders, such as smoking, high cholesterol and triglyceride levels and coronary risk, many of these linkages were not replicated in other studies or showed only weak association. In this study, Noordam et al. took advantage of the Leiden Longevity Study in order to find association between FPHL and markers of cardiovascular disease risk (e.g., serum lipid levels and hypertension) and aging (e.g., 25-hydroxyvitamin D and insulin-like growth factor). The study included 323 middle-age females, of whom 13.3% were defined as having FPHL. The researchers found that low HDL and IGF-1 levels were associated with increased risk of hair loss. Such association was not found in men with hair loss. These results warrant confirmation by additional studies; however, they suggest that risk factors for hair loss may be sex-specific.
Frontal fibrosing alopecia – possible association with leave-on facial skin care products and sunscreens; a questionnaire study
Br J Dermatol. 2016 Mar 14. doi: 10.1111/bjd.14535
Frontal fibrosing alopecia (FFA) is a type of scarring alopecia, which is becoming more and more common, mainly among post-menopausal Caucasian females. The factors that trigger this type of alopecia are still unknown. However, the fact that it is a new disorder, combined with its steadily increasing incidence, point at environmental factors as contributing to its aetiology. In this study, Aldoori et al. performed a questionnaire study to explore possible contribution of environmental factors to FFA. 102 patients were recruited to this study, and were compared to 100 age- and sex-matched controls. While the results of this study are not conclusive, they point at leave-on facial skin care products as possible causes for the hair loss, and specifically highlight the use of sunscreens as a plausible cause. While this study has several limitations, and it is still immature to draw conclusions from its results, it calls for additional similar studies to explore this suggested association.
Cancer Epidemiol. 2016 Apr;41:129-31. doi: 10.1016/j.canep.2016.02.009. Epub 2016 Mar 1
Alopecia areata (AA) has been linked previously with several disorders, including thyroid diseases and vitiligo. Recently, it has been shown that vitiligo patients have a decreases risk for melanoma and nonmelanoma skin cancers (NMSCs). This finding raised the question whether AA patients also have a decreased risk for skin cancers. In this paper, Mostaghimi et al. addressed this question by performing a retrospective cohort study. They found a significantly decreased risk for NMSC in AA patients, and a trend towards a decreased risk for developing melanoma. While these findings need to be confirmed by larger studies, they still emphasize the hypothesis that anti-melanocyte autoantigens play a role in AA.