What’s New In Hair — January 2015 | Dr. Yuval Ramot
Genome-wide meta-analysis in alopecia areata resolves HLA associations and reveals two new susceptibility loci
Nat Commun 2015 Jan 22;6:5966. doi: 10.1038/ncomms6966.
In this study, Betz et al performed a meta-analysis of the two big genome wide association studies conducted on alopecia areata patients, to achieve a total of 3,253 cases and 7,543 controls. This approach revealed two significant and one nominally significant loci that are associated with alopecia areata, in addition to the already known loci. This study underscores the importance of HLA-DR for the disease initiation, highlights again the critical role of the immune response, and unveils new emerging processes, including autophagy and apoptosis.
The genetics of alopecia areata: new approaches, new findings, new treatments
J Dermatol Sci 2015, http://dx.doi.org/10.1016/j.jdermsci.2015.01.004
In recent years, much knowledge has been acquired on the genetic basis of alopecia areata. This progress was made owing to new genetic methods and the formation of large patient registries, making the use of genome-wide association studies possible. This manuscript by Biran et al. reviews the data obtained from the different genetic studies performed throughout the years, with special emphasis on the possible therapeutic applications of these findings.
Plasmacytoid dendritic cells in alopecia areata: missing link?
J Eur Acad Dermatol Venereol. 2014 Dec 29. doi: 10.1111/jdv.12932. [Epub ahead of print]
The type I interferons (IFNs) have a critical role in the pathogenesis of alopecia areata (AA). However, their exact source is still unknown. Since plasmacytoid dendritic cells are known to be major producers of IFNs, Abou Rahal et al examined their presence in histopathological sections from AA patients. They found that plasmacytoid dendritic cells were present in all AA cases in the peribulbar area. They were absent in androgenetic alopecia cases, and located in a different distribution in trichotillomania cases.
Trichoscopic features of frontal fibrosing alopecia: Results in 249 patients
J Am Acad Dermatol 2015 Feb;72(2):357-9. doi: 10.1016/j.jaad.2014.10.039.
Trichoscopy is a powerful tool for the dermatologist to correctly diagnose different types of hair loss. Fernández-Crehuet et al have evaluated in a multi-center study the trichoscopic features of frontal fibrosing alopecia (FFA). They recruited a large number of patients to their study. Two interesting findings in this study were the discovery that the presence of cicatricial white patches were associated not only with the presence of FFA, but also with its severity. Furthermore, perifollicular erythema and follicular hyperkeratosis were associated with pruritus. This makes trichoscopy an important tool not only for the diagnosis of FFA, but also for estimating its severity.
Macrophages contribute to the cyclic activation of adult hair follicle stem cells
PLoS Biol. 2014 Dec 23;12(12):e1002002. doi: 10.1371/journal.pbio.1002002. eCollection 2014.
This manuscript provides evidence to the importance of macrophages in the regulation of the hair follicle stem cells. Using a mouse model, the authors show that reduction in macrophage number in the mesenchymal surroundings of the hair follicle leads to Wnt signaling-release and to the transformation from telogen to anagen. This provides further confirmation to the importance of epithelial-mesenchymal cross talk in the regulation of epithelial stem cell activation.
iRhom2 mutation leads to aberrant hair follicle differentiation in mice
PLoS One. 2014 Dec 29;9(12):e115114. doi: 10.1371/journal.pone.0115114. eCollection 2014.
The authors of this article found a spontaneous deletion mutation in the iRhom2 gene in the homozygous uncovered mice in a BALB/c genetic background, which has a hairless phenotype. By performing several additional functional experiments, they show that this mutation hamper the maturation of TACE, which affects the Notch1 and Wnt signaling pathway. This affects the hair shaft and inner root sheath differentiation.