Infundibular protein and RNA microarray analyses from affected and clinically non‐affected scalp in male androgenetic alopecia patients

Abstract

Non-invasive sample collection methods could facilitate clinical research on hair diseases. In an exploratory experimental study on six male volunteers with untreated androgenetic alopecia (AGA), Hamilton-Norwood stage IIIv-IV, skin surface and infundibular protein as well as RNA extracts from plucked hair follicles were analyzed from frontal skin, vertex and clinically unaffected occiput. Slightly increased levels of inflammatory markers were only found in AGAaffected scalp skin and infundibulum, not in RNA from plucked hair follicles. RNA expression profiles point towards differential expression of genes involved in hair cycle regulation, hair keratin production, but also RNA methylation and ion channel regulation. | BACKGROUNDOur current concept of androgenetic alopecia (AGA) suggests that different factors including hormonal effects, ion channel regulation, vascularization, and prostaglandins contribute to the disease onset and progression. [1][2][3] Microinflammation has been postulated to be involved. [4,5] Yet, exploratory molecular work in patients is difficult.Clinical trials largely rely on macroscopic readouts. Inclusion of biomarkers usually requires skin biopsies, limiting the number of investigational sites and frequency of sampling. Non-invasive sample collection methods could help increase our understanding of hair growth regulation. | QUESTIONS ADDRESSEDIn this pilot study, we combined clinical diagnostics with a new method for non-invasive sampling of infundibular protein [6] and RNA microarray analysis of plucked hair follicles to investigate inflammatory processes in AGA-affected scalp skin. Additionally, we looked into gene expression to identify new markers of relevance in androgenetic alopecia. | EXPERIMENTAL DESIGNSix male volunteers with untreated AGA, Hamilton-Norwood stage IIIv-IV, were included. Investigational sites (frontotemporal area, vertex, clinically unaffected occiput) were assessed (Table S1) by phototrichogram analysis, sebum and pH determination, optical coherence tomography (OCT), ultrasonography, hair root plucking (trichogram, Figure S1) and mini-zone cyanoacrylate skin surface stripping (CSSS).[6] Seborrhoeic dermatitis was an exclusion criterion.RNA from about 30 hairs from each site was obtained by hair plucking and extraction performed using RNeasy kit (Qiagen, Hilden, Germany). For hybridization, Agilent Gene Expression Hybridization kit (Agilent Technologies Inc., Santa Clara, CA, USA) was used, andCy3-labelled fragmented cRNA hybridized overnight to Agilent WholeHuman Genome Oligo Microarrays 8 × 60 K V2 using Agilent's recommended hybridization chamber and oven. The Agilent FeatureExtraction software was used to read out and process the microarray image files. Data were normalized followed by correlation analysis and differential gene expression analysis (DGA). For further details concerning study plan, methods and the microarray data, please refer to the Appendix S1. | RESULTSConsistent with the clinical diagnosis, the total hair density was significantl...

Physiological and Molecular Effects of in vivo and ex vivo Mild Skin Barrier Disruption

“…With regard to hair follicle penetration cyanoacrylate skin surface stripping (CSSS), a variation of stripping using cyanoacrylate-based resins, is of special interest. Because the liquid resin flows into hair follicle openings, it has been successfully applied for recovery of skin surface material and hair follicle material [5,6,7], as well as proposed as a penetration enhancement method [8,9,10]. For both types of application, it is important to understand the biological effects induced by the procedure not only in ex vivo experiments, but also in in vivo settings.…”

A bald statement — Current approaches to manipulate miniaturisation focus only on promoting hair growth

“…Most recently, a GWAS assessing AGA was performed which identified 71 possibly causative loci, most notably associated with 3 pathways; the Wnt signalling pathway, apoptosis and the AR signalling pathway . Aside from GWAS, transcriptomic studies, or those analysing serum content in men with AGA, have identified a myriad of other factors associated with hair loss …”

An analysis of gene expression data involving examination of signaling pathways activation reveals new insights into the mechanism of action of minoxidil topical foam in men with androgenetic alopecia

“…2 The hallmarks of AGA are alterations in hair cycle development, [3][4][5] follicular miniaturization, [6][7][8][9] and inflammation. [10][11][12] Topical minoxidil and oral finasteride have been approved by the Food and Drug Administration (USA) for the treatment of AGA. It is known that minoxidil stimulates hair growth; however, its mechanism of action is still not fully understood and needs further clarification.…”