mTOR signaling in hair follicle and hair diseases: recent progress

Mammalian target of rapamycin (mTOR) signaling pathway is a major regulator of cell proliferation and metabolism, playing significant roles in proliferation, apoptosis, inflammation, and illness. More and more evidences showed that the mTOR signaling pathway affects hair follicle circulation and maintains the stability of hair follicle stem cells. mTOR signaling may be a critical cog in Vitamin D receptor (VDR) deficiency-mediated hair follicle damage and degeneration and related alopecia disorders. This review examines the function of mTOR signaling in hair follicles and hair diseases, and talks about the underlying molecular mechanisms that mTOR signaling regulates.

Assessment of health-related quality of life in patients with frontal fibrosing alopecia

BACKGROUND

Frontal fibrosing alopecia (FFA) is a primary patterned cicatricial alopecia with different manifestations.

AIMS

Its incidence is increasing worldwide. Like other types of alopecia, FFA can affect patients' health-related quality of life (HRQOL). However, this effect has been rarely discussed. This study was designed to evaluate HRQOL in patients with FFA.

METHODS

In this cross-sectional study, 49 patients with confirmed FFA were asked to complete Dermatology Life Quality Index (DLQI) and the 36-Item Short Form Survey (SF-36) questionnaires. Disease severity was evaluated with the Frontal Fibrosing Alopecia Severity Score Index (FFASI).

RESULTS

Significant relation between SF-36 scores and other covariants was not detected. According to the DLQI, most of the patients (54%) had impaired HRQOL, which was of low grade for most of them (84%). Patients with face papules and patients who were in the group of nail, limb, and flexural involvement had significantly lower HRQOL (p-value 0.03).

CONCLUSION

We found that FFA negatively impacts HRQOL, which was more pronounced in patients with involvement of other ostensible areas.

The psychologic impact of loose anagen syndrome and short anagen syndrome

Loose anagen syndrome (LAS) and short anagen syndrome (SAS) are congenital hair disorders presenting with reduced hair length with or without hair thinning. We conducted a non-validated online questionnaire of self-identified familial participants in a Facebook support group to assess psychologic symptoms, including anxiety, depression, low self-esteem, sadness, insecurity, worry, frustration, and body dysmorphia, in patients and their caregivers. Of 163 total respondents, negative psychologic symptoms were reported in 44.2% (38/89) of LAS patients, 48.3% (43/89) of LAS caregivers, 56.8% (42/74) of SAS patients, and 47.2% (35/74) of SAS caregivers. Our data indicate that both LAS and SAS have strong psychologic, emotional, and social impacts on affected children and their caregivers.

Pili Torti: A Feature of Numerous Congenital and Acquired Conditions

Pili torti is a rare condition characterized by the presence of the hair shaft, which is flattened at irregular intervals and twisted 180° along its long axis. It is a form of hair shaft disorder with increased fragility. The condition is classified into inherited and acquired. Inherited forms may be either isolated or associated with numerous genetic diseases or syndromes (e.g., Menkes disease, Björnstad syndrome, Netherton syndrome, and Bazex-Dupré-Christol syndrome). Moreover, pili torti may be a feature of various ectodermal dysplasias (such as Rapp-Hodgkin syndrome and Ankyloblepharon-ectodermal defects-cleft lip/palate syndrome). Acquired pili torti was described in numerous forms of alopecia (e.g., lichen planopilaris, discoid lupus erythematosus, dissecting cellulitis, folliculitis decalvans, alopecia areata) as well as neoplastic and systemic diseases (such as cutaneous T-cell lymphoma, scalp metastasis of breast cancer, anorexia nervosa, malnutrition, cataracts, and chronic graft-vs.-host disease). The condition may also be induced by several drugs (epidermal growth factor receptor inhibitors, oral retinoids, sodium valproate, and carbamide perhydrate). The diagnosis of pili torti is based on trichoscopic or microscopic examination. As pili torti is a marker of numerous congenital and acquired disorders, in every case, the search for the signs of underlying conditions is recommended.

Dysbiosis and Enhanced Beta-Defensin Production in Hair Follicles of Patients with Lichen Planopilaris and Frontal Fibrosing Alopecia

Despite their distinct clinical manifestation, frontal fibrosing alopecia (FFA) and lichen planopilaris (LPP) display similar histopathologic features. Aberrant innate immune responses to endogenous or exogenous triggers have been discussed as factors that could drive inflammatory cascades and the collapse of the stem cell niche. In this exploratory study, we investigate the bacterial composition of scalp skin and plucked hair follicles (HF) of patients with FFA, LPP and alopecia areata circumscripta (AAc), as well as healthy individuals, in relation to cellular infiltrates and the expression of defense mediators. The most abundant genus in lesional and non-lesional HFs of LPP and FFA patients was Staphylococcus, while Lawsonella dominated in healthy individuals and in AAc patients. We observed statistically significant differences in the ratio of Firmicutes to Actinobacteria between healthy scalp, lesional, and non-lesional sites of FFA and LPP patients. This marked dysbiosis in FFA and LPP in compartments close to the bulge was associated with increased HβD1 and HβD2 expression along the HFs from lesional sites, while IL-17A was increased in lesional HF from AAc patients. The data encourage further studies on how exogenous factors and molecular interactions across the HF epithelium could contribute to disease onset and propagation.

The Potential Relevance of the Microbiome to Hair Physiology and Regeneration: The Emerging Role of Metagenomics

Human skin and hair follicles are recognized sites of microbial colonization. These microbiota help regulate host immune mechanisms via an interplay between microbes and immune cells, influencing homeostasis and inflammation. Bacteria affect immune responses by controlling the local inflammatory milieu, the breakdown of which can result in chronic inflammatory disorders. Follicular microbiome shifts described in some inflammatory cutaneous diseases suggest a link between their development or perpetuation and dysbiosis. Though the hair follicle infundibulum is an area of intense immunological interactions, bulb and bulge regions represent immune-privileged niches. Immune privilege maintenance seems essential for hair growth and regeneration, as collapse and inflammation characterize inflammatory hair disorders like alopecia areata and primary cicatricial alopecia. Current research largely focuses on immunological aberrations. However, studies suggest that external stimuli and interactions across the follicular epithelium can have profound effects on the local immune system, homeostasis, and cycling. Herein, we review hair follicle bacterial colonization, its possible effects on the underlying tissue, and links to the pathogenesis of alopecia, beyond the pure investigation of specific species abundance. As skin microbiology enters the metagenomics era, multi-dimensional approaches will enable a new level of investigations on the effects of microorganisms and metabolism on host tissue.

Synthetic hair reactions and treatment of complications: Case reports

BACKGROUND

Synthetic hair fiber implantation first achieved widespread use in the 1970s, but in 1983, the US Federal Drug Administration banned the fibers due to its complications. Currently available synthetic fibers consist of polyamide material, which has been claimed to be effective and safe. Nevertheless, its use for hair restoration is controversial because of complications such as recurrent infections; the rejection and the faster-than-anticipated loss of fibers; frequent allergic reactions; fears about carcinogenicity; cicatricial alopecia; granulomatous hypersensitivity; and cyst formation.

AIMS

To report complications of synthetic hair implantation and treatments.

METHODS

We report the clinical data, pathological studies, and treatment outcomes of two patients who developed complications after a synthetic hair implantation.

RESULTS

Our case reports showed significant moderate-to-severe adverse events, including recurrent folliculitis, scalp crusting, scarring, the matting and breakage of fibers, and granulomatous reactions. The onset of the reactions varied between 1 and 8 weeks. Pathological studies showed that the implantation of the synthetic hair into the scalp produced a hyperplastic proliferation of epidermal cells, foreign body granuloma, and persistent acute inflammation due to bacterial infections. In our study, definitive treatment was ineffective until the synthetic fibers were removed from the scalp.

CONCLUSION

These significant adverse reactions may limit the benefits of synthetic hair fiber implantation for some patients. Although the inflammations were initially controlled by oral and topical antibiotics, a variety of antibiotics were unable to control the folliculitis. The fibers were ultimately removed, following which, the inflammations improved.

Trichoscopic evaluation of frontal hairline recession in Egyptian female patients

BACKGROUND

Since frontal hairline is the most characteristic feature of the face for both men and women, affecting the psychological state of patients, hair loss has been considered to be one of the most prominent esthetic problems. Hair loss either resulting from the androgenetic or nonandrogenetic origin is characterized by changes in the anterior line.

AIM

The aim of this study was to evaluate the causes of the frontal hairline recession in Egyptian female patients using trichoscopy and to detect the prevalence of each of those causes in Egyptian females.

PATIENTS AND METHODS

This study was performed on a total of 200 Egyptian female patients aged between 15 and 65 years who complained of frontal hairline recession. All patients were derived from Al-Zahraa University hospital outpatient clinic over a period from November 2017 to April 2019. We classified them into two groups according to age: Group A: 15-45 and Group B: 46-65. After full history taking, general and dermatological examination, photographs of hair recession were taken from both frontal and temporal sides. Then, the trichoscopic examination by noncontact dermoscopy was done photographed and evaluated.

RESULTS

The most common cause of the frontal hairline recession in Egyptian female patients was androgenetic alopecia (AGA) (50%). Most of the patients were of old age (58%). The high statistically significant trichoscopic findings in androgenetic alopecia were yellow dots, peripilar sign, hair diameter diversity, and single-hair pilosebaceous unit (45.0%, 61.0%, 100.0%, and 96.0%), respectively. On the other hand, perifollicular scaling, absence of hair follicles, and lonely hair revealed a high statistically significant presentation (88.9%, 100.0%, and 22.2%), respectively, with frontal fibrosing alopecia, and vellus hair (100.0%) and perifollicular casts (91.8%) with tractional alopecia. Finally, hair broken at different levels (100%), black powder (88.9%), black dots (100.0%), hook hairs (11.1%), i hair (16.7%),V sign (44.4%), flame hairs (33.3%), coiled hair (5.6%), and burnt match stick sign (5.6%) showed a high statistically significance presentation with trichotillomania.

CONCLUSION

The present study supports the trichoscopic criteria for the diagnosis of causes of frontal hairline recession, which provide a noninvasive diagnostic tool compared with histopathological diagnosis.

Hair diseases: a big problem on a small surface

Civilizational progress initially contributes to the problem of hair loss and then to alopecia as regards both frequency and therapeutic dilemmas. The work presents trichological problems which occur more rarely, i.e. drug-induced, anagen and telogen alopecia, congenital and acquired structural hair disorders, psychic disturbances concerning the hair as well as the hair during menopause. Then, the article briefly describes contagious (infectious) diseases as well as diseases with inflammatory etiology which are accompanied by exfoliation and (frequently) pruritus. Finally, alopecia cicatricans is discussed. Alopecia areata and androgenetic alopecia are omitted herein because they occur more often and will be described in another work. Any disproportions and upset balance concerning correct functioning of mechanisms within the scalp hair system are the evidence of pathologies.

Hair care practices and structural evaluation of scalp and hair shaft parameters in African American and Caucasian women

How African American hair fragility relates to hair care practices and biologic differences between races is not well understood. To assess the differences between perceptions of hair health, hair care practices, and several biologic hair parameters between Caucasian and African American women. A questionnaire on perceptions of hair health and hair care practices was administered. Biological and structural parameters of hair shaft and scalp, including growth, density, diameter, cycle, breakage, and scalp blood flow were also assessed in this case-control study. Significant differences between the Caucasian and African American women were observed in the questionnaire and biologic study data. Regarding self-reported perceptions of hair health, there were differences in the following: hair shaft type (P < 0.001), hair breakage (P = 0.040), and desire to change hair (P = 0.001). Regarding self-reported hair care practices, there were differences in the following: location of haircutting (P = 0.002) and washing (P = 0.010), washing frequency (P < 0.001), chemical relaxer use (P < 0.001), hooded hair dryer use (P < 0.001), and hair shaft conditioner use (P = 0.005). The two groups had similar practices in regard to the use of hair color, frequency of hair color use, chemical curling agents, and handheld blow dryer use. Regarding biological and structural parameters, there were differences in the following: hair growth rate (P < 0.001), density (P = 0.0016), diameter (P = 0.01), number of broken hairs (P < 0.001), and blood flow (P = 0.03). There was no significant difference in hair cycle parameters.The differences in hair care practices and hair fiber morphology among African American women may contribute to clinically observed variation in hair fragility and growth.