What’s new in hair — August 2017 | Dr. Claire A. Higgins
Glycolipid and Hormonal Profiles in Young Men with Early-Onset Androgenetic Alopecia: A meta-analysis
Sci Rep. 2017 Aug 10;7(1):7801. doi: 10.1038/s41598-017-08528-3.
Androgenetic alopecia (AGA), otherwise known as male pattern baldness, affects 50% of men by age 50. If hair loss occurs before the age of 35, it is considered as early onset. In this study, Cannarella et al performed a meta-analysis to assess the glycolipid and hormonal profiles in young men with early onset AGA. After originally identifying 10596 manuscripts with possible relevance, they applied exclusion and eligibility criteria, narrowing their focus to 7 manuscripts whose data was to be included in the meta-analysis. Upon analysis of these manuscripts which incorporated 522 men with early-onset AGA and 487 controls, they found that insulin serum levels, serum total cholesterol, LDL cholesterol and triglycerides were significantly higher in AGA patients compared to controls. Men with early onset AGA also had a higher body mass index than controls, however it is unclear if these differences are causative and related to AGA onset, or whether the psychological effects of AGA are causing weight gain and an unhealthy lifestyle. In the manuscript, the authors highlight that there have been previous associations between early onset AGA and type II diabetes and cardiovascular disease, and suggest that patients with AGA should have their body mass index monitored to prevent long term effects on their health. In addition, the authors looked at hormonal profiles in patients, and found that the hormonal pattern of men with early onset AGA resembled that of women with polycystic ovarian syndrome (PCOS). It has previously been suggested that early onset AGA is the male equivalent of PCOS, and this meta-analysis adds weight to this suggestion.
Int J Trichology. 2017 Apr-Jun;9(2):54-57. doi: 10.4103/ijt.ijt_100_16.
One alternative to pharmacological or surgical intervention to treat hair loss is to use spray on hair fibres, also known as reconstructive hair fibres. These fibres electrostatically adhere to hair already on the scalp, and can be used to camouflage the scalp giving the appearance of fuller and denser hair. In this manuscript, Combalia et al use scanning electron microscopy and X-ray microanalysis to assess the structure and chemical composition of 5 reconstructive hair fibre products. All 5 of these products gave comparable cosmetic results when used in patients with androgenetic alopecia, telogen effluvium or trichotillomania, however in alopecia areata they were ineffective, suggesting that they cannot adhere to scalp without any residual hair fibres. On analysing structure, the authors found that three of the products produced from a vegetal source contained fibres in a parallel orientation. The remaining two products were from a keratin source (sheep wool keratin or pure keratin) and these produced fibres with a scaly appearance, almost like the cuticle found on human hair fibres. All fibres contained Carbon and Oxygen, and while the vegetal hair fibres had low amounts of Sulphur this was present at high levels in the keratin based fibres. Despite differences in their composition and morphology, all of these fibres were quite effective cosmetically. As such, reconstructive hair fibres may be suitable for patients who suffer from psychological distress as a result of their hair loss.
Nat Cell Biol. 2017 Sep;19(9):1017-1026. doi: 10.1038/ncb3575. Epub 2017 Aug 14.
The hair follicle bulge houses epithelial stem cells which are critical for hair growth, and transition from a resting state telogen back into the growth state anagen. Numerous markers of bulge stem cells have been identified, and determining the role of these genes in stem cell activation is a mainstay in follicular research. In this study, Flores et al looked specifically at metabolism in hair follicle bulge cells identifying that glycolytic metabolites such as lactate, but not TCA metabolites, were routinely higher in hair follicle stem cells compared to stem cells in the interfollicular epidermis. They also found that lactate dehydrogenase was expressed within the hair follicle bulge, but not other cells within the follicle. To delve further into the role of lactate metabolism in the hair cycle the authors conducted both gain of function and loss of function experiments, both genetically and pharmacologically in mouse skin. They found that hair follicles with no lactate dehydrogenase failed to transition from telogen into anagen, however, when lactate production was enhanced hair follicles transition through the cycle stages was accelerated. It was not addressed whether anagen itself occurred faster as a result of this accelerated cycling, and the produced hair was the same length as normal hair, or whether the accelerated anagen was related to the decreased duration between the cycle transitions and therefore resulted in shorter hair. However, what was intriguing was that activating lactate production within the bulge had the described effect on the hair cycle, while activating it at the top of the follicle in the infundibular region had no effect on the cycle. Therefore, lactate production needs to be active in the bulge stem cells for accelerated transition from telogen to anagen.
Comparative genomics analyses of alpha-keratins reveal insights into evolutionary adaptation of marine mammals
Front Zool. 2017 Aug 2;14:41. doi: 10.1186/s12983-017-0225-x. eCollection 2017.
Marine mammals are generally categorised into 5 groups; pinnipeds, cetacenas, sea otters, sirenians and polar bears. The emergence of hair on these mammals is a major step in their evolution, however, there are differences between the mammalian groups. Seals, in the pinniped categorisation, have a thin coat of fur, while cetacenas (whales and dolphins) and sirenians (manatees) lack a hair coat completely. Sea otters have an exceptionally thick coat of fur, while polar bears have a dense underfur and lower number of guard hairs on their coat. In this study, Sun et al performed comparative genomics of alpha-keratins, from which hair keratin is formed, in 11 marine mammals from 4 of these 5 groups; 7 cetacenas, 2 pinnipeds,1 sirenian and 1 polar bear, and compared them to their terrestrial relatives. The terrestrial relative of the polar bear is the giant panda, the relative of the sirenian manatee is the elephant, while cows, sheep and alpacas are relatives to dolphins and whales (cetacenas). Most interesting was the finding that whales and dolphins, which are hairless, exclusively lost several keratin genes including K33A, K33B, K73 and K74, while these were present in their terrestrial relatives. K33A and K33B are present in the cortex of the hair fibre while K73 and K74 are found in the inner root sheath with mutations in K74 resulting in autosomal dominant woolly hair and hypotrichosis. This manuscript gives insights into the alpha-keratins which are important for evolution of hair, and the keratins which contribute to the diverse hair phenotypes observed in marine mammals.
Am J Clin Dermatol. 2017 Aug 11. doi: 10.1007/s40257-017-0312-y. [Epub ahead of print]
Alopecia areata (AA) is an autoimmune disease which results in hair loss, and is characterised by a strong Interferon (IFN) signature. Triggering events, such as emotional stress, infections and drugs are thought to induce an IFN response, and be causal in the onset of AA. In this manuscript, Richardson et al searched the Electronic Medical Record database at the University of Rochester Medical Center, to identify patients with AA and co-existing medical conditions which may serve as a triggering event. Associating AA with other conditions, they found that AA was significantly more prevalent in patients who had received either the hepatitis B vaccine, the hepatitis A vaccine, cytomegalovirus or IFN-β treatment. The odds of a patient receiving either the hepatitis A or B vaccine, or having IFN-β treatment and having AA were significantly increased over patients who did not receive a vaccine or treatment. The bioinformatics analysis in this manuscript therefore suggests that exposure to specific vaccines, such as hepatitis A or B, can serve as a triggering event and lead to an IFN response eliciting AA.
J Eur Acad Dermatol Venereol. 2017 Aug 31. doi: 10.1111/jdv.14571. [Epub ahead of print]
Frontal fibrosing alopecia (FFA) is a form of scarring alopecia which has gradually increased in prevalence since the 1990’s. Research into FFA was identified as one of the top ten research priorities by the British Hair and Nail Society which was discussed in last month’s What’s new in hair EHRS blog. In this manuscript, Vazquez-Herrera et al used a non-invasive imaging technique known as Optimal Coherence Technology (OCT) to increase our understanding of FFA. OCT is a medical imaging technique which utilises near-infrared light to visualise tissues. Light penetrates the sample, in this case skin, and the scattering pattern of the light provides information about the tissue structure. Thus with skin, OCT enables acquisition of relatively high resolution images up to 2 mm beneath the skin surface. In this paper, using OCT to image inflammatory and alopecic regions in 4 patients with FFA, and 3 controls, the authors found that inflammatory epidermis was slightly thicker than controls, which alopecic epidermis was thinner than controls. Blood flow was also decreased in the alopecic band, while in the inflammatory band it was increased relative to controls. This coincided with an irregular distribution of collagen in the inflammatory band of patients with FFA. Little is known about the onset or progression of FFA, however tools such as OCT will enable non-invasive monitoring of patients as disease progresses, and could be useful to evaluate therapeutic response over time.