The contribution of endogenous and exogenous factors to female alopecia: a study of identical twins

Comparative analysis of scalp and gut microbiome in androgenetic alopecia: A Korean cross-sectional study

Androgenetic alopecia (AGA) is a non-scarring and progressive form of hair loss occurring in both men and women. Although genetic predisposition and sex steroid hormones are the main causes, many factors remain unknown, and various extrinsic factors can negatively affect the lifespan of hair. We investigated skin-gut axis microorganisms as potential exogenous factors causing AGA, through comparative analyses of the scalp and gut microbiome in individuals with and without AGA in a Korean cohort. Using 16S rRNA gene sequencing, we characterized the scalp and gut microbiomes of 141 individuals divided into groups by sex and presence of AGA. Alpha diversity indices in the scalp microbiome were generally higher in individuals with AGA than in healthy controls. These indices showed a strong negative correlation with scalp-inhabitant bacteria (Cutibacterium and Staphylococcus), indicating that the appearance of non-inhabitant bacteria increases as hair loss progresses. No significant differences in diversity were observed between the gut microbiomes. However, bacterial functional differences, such as bile acid synthesis and bacterial invasion of epithelial cells, which are related to intestinal homeostasis, were observed. The networks of the scalp and gut microbiome were more complex and denser with higher values of the network topology statistic coefficient values (i.e., transitivity, density, and degree centrality) and more unique associations in individuals with AGA than in healthy controls. Our findings reveal a link between skin-gut microorganisms and AGA, indicating the former's potential involvement in the latter's development. Additionally, these results provide evidence for the development of cosmetics and therapeutics using microorganisms and metabolites involved in AGA.

Comorbidities in Androgenetic Alopecia: A Comprehensive Review

Androgenetic alopecia is the most common form of hair loss, affecting 85% of men and 40% of women. Androgenetic alopecia is a disease caused by multiple factors, such as genetics, hormones, and systemic diseases; however, the exact cause remains undetermined. Recent studies have found that it is associated with a high incidence of endocrine diseases and other comorbidities. It may not only be a skin disease but also an early signal of underlying systemic diseases. Effective management requires timely diagnosis and treatment initiation. However, in current clinical practice, androgenetic alopecia is still not fully understood or treated. Recognizing the true physical, social, and emotional burden of androgenic alopecia, as well as its associated comorbidities, is the first step in improving the prognosis of affected patients. This review aimed to gather the known pathological factors and provide a reference for clinical physicians to understand androgenetic alopecia and its comorbidities in depth, thereby enabling early recognition of the underlying systemic diseases and providing timely treatment.

Role of smoking in androgenetic alopecia: A systematic review

Smoking and its role in Androgenetic Alopecia has long been debated. Smoking may lead to hair loss by vasoconstriction, by forming DNA adducts, free radical damage to hair follicle, by enhancing senescence and hormonal effects. We have reviewed the available literature on AGA and smoking. Data available show that there is a significant association between smoking and AGA. However, studies demonstrating the benefit of avoidance of smoking in improving hair loss are lacking. Furthermore, large controlled studies with histological documentation are still unavailable to affirm the findings.

The Effects of Smoking on Hair Health: A Systematic Review

Smoking is not only a preventable cause of significant systemic disease but also affects the follicular growth cycle and fiber pigmentation. Ambient tobacco smoke exposure results in nicotine accumulation in hair follicles and the hair shaft. This review summarizes the evidence on the association between smoking and hair health, as denoted by alopecia and premature hair graying (PHG). In July 2020, a review of the literature using PubMed/MEDLINE and CINAHL databases identified 32 studies investigating the relationship between smoking, PHG, and alopecia (androgenetic alopecia and frontal fibrosing alopecia). The prevalence of hair loss and PHG is more prevalent in smokers than nonsmokers. Smoking is associated with negative effects on hair health as evidenced in PHG and alopecia. Smoking status should be assessed in patients who are presenting to their dermatologist for evaluation of alopecia and PHG.

New effects of caffeine on corticotropin-releasing hormone (CRH)-induced stress along the intrafollicular classical hypothalamic-pituitary-adrenal (HPA) axis (CRH-R1/2, IP3 -R, ACTH, MC-R2) and the neurogenic non-HPA axis (substance P, p75NTR and TrkA) in ex vivo human male androgenetic scalp hair follicles

BACKGROUND

Human hair is highly responsive to stress, and human scalp hair follicles (HFs) contain a peripheral neuroendocrine equivalent of the systemic hypothalamic-pituitary-adrenal (HPA) stress axis. Androgenetic alopecia (AGA) is supposed to be aggravated by stress. We used corticotropin-releasing hormone (CRH), which triggers the HPA axis, to induce a stress response in human ex vivo male AGA HFs. Caffeine is known to reverse testosterone-mediated hair growth inhibition in the same hair organ culture model.

OBJECTIVES

To investigate whether caffeine would antagonize CRH-mediated stress in these HFs.

METHODS

HFs from balding vertex area scalp biopsies of men affected by AGA were incubated with CRH (10-7 mol L-1 ) with or without caffeine (0·001% or 0·005%).

RESULTS

Compared to controls, CRH significantly enhanced the expression of catagen-inducing transforming growth factor-β2 (TGF-β2) (P < 0·001), CRH receptors 1 and 2 (CRH-R1/2) (P < 0·01), adrenocorticotropic hormone (ACTH) (P < 0·001) and melanocortin receptor 2 (MC-R2) (P < 0·001), and additional stress-associated parameters, substance P and p75 neurotrophin receptor (p75NTR ). CRH inhibited matrix keratinocyte proliferation and expression of anagen-promoting insulin-like growth factor-1 (IGF-1) and the pro-proliferative nerve growth factor receptor NGF-tyrosine kinase receptor A (TrkA). Caffeine significantly counteracted all described stress effects and additionally enhanced inositol trisphosphate receptor (IP3 -R), for the first time detected in human HFs.

CONCLUSIONS

These findings provide the first evidence in ex vivo human AGA HFs that the stress mediator CRH induces not only a complex intrafollicular HPA response, but also a non-HPA-related stress response. Moreover, we show that these effects can be effectively antagonized by caffeine. Thus, these data strongly support the hypothesis that stress can impair human hair physiology and induce hair loss, and that caffeine may effectively counteract stress-induced hair damage and possibly prevent stress-induced hair loss.

Particulate Matters Induce Apoptosis in Human Hair Follicular Keratinocytes

Background

Particulate matters (PM) comprise a heterogeneous mixture of particles suspended in air. A recent study found that urban PMs may penetrate into hair follicles via transfollicular and transdermal routes in dorsal skin.

Objective

To investigate the effects of PM on ex vivo cultured human scalp hair follicles and hair follicular keratinocytes in vitro.

Methods

TUNEL staining was employed to check cells undergoing apoptosis in cultured hair follicles after PM treatment. MTT assay was employed to check cell viability after PM treatment. Quantitative real-time PCR analysis was employed to quantitate the expression of inflammatory genes, matrix metalloproteinases (MMPs), and Duox1. Inflammatory cytokine levels were measured by ELISA after PM treatment. The level of reactive oxygen species (ROS) production was measured using a chemical fluorescent probe by a fluorescence plate reader.

Results

Abundant TUNEL-positive cells were observed in the keratinocyte region of hair including the epidermis, sebaceous gland, outer root sheath (ORS), inner root sheath (IRS), and bulb region. The viability of follicular cells, including the ORS, was found to be decreased upon PM exposure. mRNA expression and protein levels of inflammatory response genes and MMPs were upregulated in a dose-dependent manner by PM treatment. ROS levels were also increased by PM.

Conclusion

These data strongly suggest that penetrated PMs from air pollution may cause apoptotic cell death to follicular keratinocytes by increased production of ROS and inflammatory cytokines, which could impair hair growth.

Female Pattern Hair Loss-An Update

Female pattern hair loss (FPHL) is nonscarring progressive thinning of hair with gradual decrease in the number of hair, especially in the frontal, central, and parietal scalp, due to a process known as follicular miniaturization. The etiopathogenesis of FPHL is complex with multiple factors such as genetics, inflammation, hormones, and environment playing role in it. It usually manifests as slowly progressive hair thinning, mainly over the vertex and upper parietal scalp, the frontal hairline is often spared and the miniaturization is also not as severe as in men. A thorough history, clinical examination, hair loss evaluation tests, dermoscopy, and scalp biopsy can help in establishing the diagnosis. Various biochemical tests may be needed in patients with hyperandrogenism. The treatment includes medical and surgical modalities. Topical minoxidil is still considered the first line of treatment. Along with medical therapy, cosmetic camouflage may also be needed in some cases.

Physiopathology and current treatments of androgenetic alopecia: Going beyond androgens and anti-androgens

Androgenetic alopecia (AGA) is the most diagnosed hair loss dysfunction. Its physiopathology comprises a genetic predisposition affording an exacerbated response of the hair follicles cells to androgens aggravated by scalp inflammation and extrinsic factors. This paper presents a review of the mechanisms and extrinsic factors involved in the AGA physiopathology as well as its conventional and emerging treatments. The research focused on reports regarding AGA physiopathology and treatments published between January 2001 and July 2019 in medical and related journals. The most used medical treatments for AGA-minoxidil and finasteride-present non satisfactory results in some cases. Currently, the low-level laser therapy is recognized as a safe and effective treatment for AGA. Some minimally invasive techniques-mesotherapy, microneedling, carboxytherapy, and platelet-rich plasma-are also used to stimulate hair growth. Pharmaceutical substances with mechanisms differing from the anti-androgen activity are under current investigation and many of them have botanical origins; however, formulations with higher performance are required, and the hair follicles ability of being a drug and nanoparticle reservoir has been researched. The association of different strategies, that is, substances with synergic mechanisms and the use of advantageous technologies associated with lifestyle changes could improve the treatment outcomes.

Alopecia in rhesus macaques (Macaca mulatta): Association with pregnancy and chronic stress

BACKGROUND

Alopecia in captive non-human primates is often presented as a welfare issue. However, it is a complex condition with a number of possible causes. The purpose of this study was to assess the impact of pregnancy and hair cortisol concentrations on alopecia in rhesus macaques.

METHODS

Subjects were 113 socially housed adult female rhesus macaques (27 pregnant, 35 nursing infants, 51 controls). During routine physicals, photographs were taken for alopecia assessment and hair samples were collected for cortisol assay.

RESULTS

Alopecia was more prevalent in pregnant than in control females, but there was no association between alopecia and hair cortisol. However, there was a significant effect of pregnancy on hair cortisol. Nursing females had higher hair cortisol levels than pregnant females, which had higher levels than control females.

CONCLUSIONS

Although alopecia does not appear to be associated with hair cortisol, both alopecia and hair cortisol were associated with pregnancy.

Both low circulating insulin-like growth factor-1 and high-density lipoprotein cholesterol are associated with hair loss in middle-aged women

BACKGROUND

Multiple biomarkers have been associated with hair loss in women, but studies have shown inconsistent results.

OBJECTIVES

We investigated the associations between markers of cardiovascular disease risk (e.g. serum lipid levels and hypertension) and ageing [e.g. 25-hydroxyvitamin D and insulin-like growth factor (IGF)] with hair loss in a population of middle-aged women.

METHODS

In a random subgroup of 323 middle-aged women (mean age 61·5 years) from the Leiden Longevity Study, hair loss was graded by three assessors using the Sinclair scale; women with a mean score > 1·5 were classified as cases with hair loss.

RESULTS

Every 1 SD increase in high-density lipoprotein (HDL) cholesterol was associated with a 0·65-times lower risk [95% confidence interval (CI) 0·46-0·91] of hair loss. For IGF-1 the risk was 0·68 times lower (95% CI 0·48-0·97) per 1 SD increase, independently of the other studied variables. Women with both IGF-1 and HDL cholesterol levels below the medians of the study population had a 3·47-times higher risk (95% CI 1·30-9·25) of having hair loss.

CONCLUSIONS

Low HDL cholesterol and IGF-1 were associated with a higher risk of hair loss in women. However, further studies are required to infer causal relationships.

Female Pattern Hair Loss: a clinical and pathophysiological review

Female Pattern Hair Loss or female androgenetic alopecia is the main cause of hair loss in adult women and has a major impact on patients' quality of life. It evolves from the progressive miniaturization of follicles that lead to a subsequent decrease of the hair density, leading to a non-scarring diffuse alopecia, with characteristic clinical, dermoscopic and histological patterns. In spite of the high frequency of the disease and the relevance of its psychological impact, its pathogenesis is not yet fully understood, being influenced by genetic, hormonal and environmental factors. In addition, response to treatment is variable. In this article, authors discuss the main clinical, epidemiological and pathophysiological aspects of female pattern hair loss.

A 3-month, randomized, double-blind, placebo-controlled study evaluating the ability of an extra-strength marine protein supplement to promote hair growth and decrease shedding in women with self-perceived thinning hair

An oral marine protein supplement (MPS) is designed to promote hair growth in women with temporary thinning hair (Viviscal Extra Strength; Lifes2good, Inc., Chicago, IL). This double-blind, placebo-controlled study assessed the ability of MPS to promote terminal hair growth in adult women with self-perceived thinning hair associated with poor diet, stress, hormonal influences, or abnormal menstrual cycles. Adult women with thinning hair were randomized to receive MPS (N = 30) or placebo (N = 30) twice daily for 90 days. Digital images were obtained from a 4 cm(2) area scalp target area. Each subject's hair was washed and shed hairs were collected and counted. After 90 days, these measures were repeated and subjects completed Quality of Life and Self-Assessment Questionnaires. MPS-treated subjects achieved a significant increase in the number of terminal hairs within the target area (P < 0.0001) which was significantly greater than placebo (P < 0.0001). MPS use also resulted in significantly less hair shedding (P = 0.002) and higher total Self-Assessment (P = 0.006) and Quality of Life Questionnaires scores (P = 0.035). There were no reported adverse events. MPS promotes hair growth and decreases hair loss in women suffering from temporary thinning hair. This trial is registered with ClinicalTrials.gov Identifier: NCT02297360.

Environmental factors that contribute to upper eyelid ptosis: a study of identical twins

BACKGROUND

Current literature provides little information about the impact of environmental exposures on the severity of acquired blepharoptosis.

OBJECTIVE

The authors assessed environmental factors that may contribute to eyelid ptosis in a population of identical twins.

METHODS

Photographs of 286 sets of twins from a prospectively collected database from 2008 to 2010 were reviewed. The authors identified 96 sets of identical twins (192 individual persons) who had differing severity of ptosis. Digital photographs were analyzed, and the degree of ptosis was measured in each eye of every subject. The external factors that could potentially contribute to blepharoptosis were taken into consideration. The authors then assessed the correlations of 9 different environmental risk factors with ptosis. Generalized linear mixed model were constructed to determine the associations of ptosis measurements with environmental risk factors obtained from the subject survey database.

RESULTS

The mean level of upper eyelid ptosis in the study population was 1.1 mm. The mean difference in ptosis between twins was 0.5 mm. Wearing contact lenses, either hard or soft, was significantly associated with ptosis. The mean ptosis measurement among twins who did not wear contact lenses was 1.0 mm; for those who wore soft contact lenses, the mean was 1.41 mm, and for those who wore hard contact lenses, the mean was 1.84 mm.

CONCLUSIONS

Acquired ptosis is not linked to body mass index, smoking behavior, sun exposure, alcohol use, work stress, or sleep. Wearing either hard or soft lenses was associated with an increased risk of ptosis. These influences are independent of genetic predisposition.

LEVEL OF EVIDENCE

3 Diagnostic.

Androgenic alopecia is associated with less dietary soy, lower [corrected] blood vanadium and rs1160312 1 polymorphism in Taiwanese communities

Background

Although the genetic basis of androgenic alopecia has been clearly established, little is known about its non-genetic causes, such as environmental and lifestyle factors.

Objective

This study investigated blood and urine heavy metals concentrations, environmental exposure factors, personal behaviors, dietary intakes and the genotypes of related susceptibility genes in patients with androgenic alopecia (AGA).

Design

Age, AGA level, residence area, work hours, sleep patterns, cigarette usage, alcohol consumption, betel nut usage, hair treatments, eating habits, body heavy metals concentrations and rs1998076, rs913063, rs1160312 and rs201571 SNP genotype data were collected from 354 men. Logistic regression analysis was performed to examine whether any of the factors displayed odds ratios (ORs) indicating association with moderate to severe AGA (≧IV). Subsequently, Hosmer-Lemeshow, Nagelkerke R² and accuracy tests were conducted to help establish an optimal model.

Results

Moderate to severe AGA was associated with the AA genotype of rs1160312 (22.50, 95% CI 3.99–126.83), blood vanadium concentration (0.02, 95% CI 0.01–0.04), and regular consumption of soy bean drinks (0.23, 95% CI 0.06–0.85), after adjustment for age. The results were corroborated by the Hosmer-Lemeshow test (P = 0.73), Nagelkerke R² (0.59), accuracy test (0.816) and area under the curve (AUC; 0.90, 0.847–0.951) analysis.

Conclusions

Blood vanadium and frequent soy bean drink consumption may provide protect effects against AGA. Accordingly, blood vanadium concentrations, the AA genotype of rs1160312 and frequent consumption of soy bean drinks are associated with AGA.