Peroxisome proliferator-activated receptor-γ signalling protects hair follicle stem cells from chemotherapy-induced apoptosis and epithelial-mesenchymal transition.

BACKGROUND: Permanent chemotherapy-induced alopecia (pCIA), for which preventive interventions remain limited, can manifest with scarring. While the underlying pathomechanisms of pCIA are unclear, depletion of epithelial hair follicle (HF) stem cells (eHFSCs) is likely to play a role. OBJECTIVES: To explore the hypothesis that, besides apoptosis, eHFSCs undergo pathological epithelial-mesenchymal transition (EMT) in pCIA, thus explaining the scarring phenotype. Furthermore, we tested whether a peroxisome proliferator-activated receptor (PPAR)-γ modulator could prevent pCIA-associated pathomechanisms. METHODS: Organ-cultured human scalp HFs were treated with the cyclophosphamide metabolite 4-hydroperoxycyclophosphamide (4-HC). Additionally, HFs were pretreated with the agonistic PPAR-γ modulator N-acetyl-GED-0507-34-Levo (NAGED), which has previously been shown to promote K15 expression and antagonize EMT in eHFSCs. RESULTS: In accordance with anticipated hair bulb cytotoxicity, dystrophy and catagen induction, 4-HC promoted apoptosis along with increased p53 expression, DNA damage and pathological EMT in keratin 15+ (K15) eHFSCs, as evidenced by decreased E-cadherin expression and the appearance of fibronectin+ and vimentin+ cells in the hair bulge. Pretreatment with NAGED protected against 4-HC-induced hair bulb cytotoxicity/dystrophy, and apoptosis, p53 upregulation and EMT in the bulge, thereby significantly preventing depletion of K15+ human eHFSCs ex vivo. CONCLUSIONS: Since a key cyclophosphamide metabolite alone suffices to damage and deplete human scalp eHFSCs by promoting apoptosis, DNA damage and EMT ex vivo, strategies to prevent pCIA need to target these pathomechanisms. Given the ability of NAGED to prevent chemotherapy-induced eHFSCs damage ex vivo, our study introduces the stimulation of PPAR-γ signalling as a novel intervention strategy for the prevention of pCIA.

Alopecia areata in patients with systemic lupus erythematosus treated with belimumab: a plausible association.

Belimumab, an anti-B-lymphocyte stimulator monoclonal antibody, was recently approved for the treatment of systemic lupus erythematosus. Alopecia areata is characterized by an acute immune-mediated hair loss. Herein, we report on three adult systemic lupus erythematosus patients who developed alopecia areata in association with belimumab treatment. Alopecia areata was resolved in all three patients and belimumab was discontinued in two of them. Thus, in the current report, we explore the plausible link between alopecia areata and belimumab.

Theophylline exerts complex anti-ageing and anti-cytotoxicity effects in human skin ex vivo.

OBJECTIVE: Theophylline is a phosphodiesterase inhibitor that is being used clinically for asthma therapy. In addition, it is recognized as a cosmetic agent with possible anti-ageing and anti-oxidative properties. Nevertheless, how it affects human skin is still poorly examined. METHODS: Theophylline (10 or 100 µM) was administered to the culture medium of full-thickness human skin ex vivo for 24 or 72 h. RESULTS: Theophylline stimulated protein expression of the anti-oxidant metallothionein-1 and mRNA levels of collagen I and III. Assessment of fibrillin-1 immunohistology revealed enhanced structural stability of dermal microfibrils. Theophylline also exerted extracellular matrix-protective effects by decreasing MMP-2 and MMP-9 mRNA levels, partially antagonizing the effects of menadione, the potent, toxic ROS donor. In addition, it decreased menadione-stimulated epidermal keratinocytes apoptosis. Interestingly, theophylline also increased the level of intracutaneously produced melatonin, that is the most potent ROS-protective and DNA damage repair neuromediator, and tendentially increased protein expression of MT1, the melatonin receptor. Theophylline also increased the expression of keratin 15, the stem cell marker, in the epidermal basal layer but did not change mitochondrial activity or epidermal pigmentation. CONCLUSION: This ex vivo pilot study in human skin shows that theophylline possesses several interesting complex skin-protective properties. It encourages further examination of theophylline as a topical candidate for anti-ageing treatment.

OBJECTIF: la théophylline est un inhibiteur de la phosphodiestérase actuellement utilisée en clinique pour le traitement de l'asthme. En outre, elle est reconnue comme étant un agent cosmétique ayant des propriétés potentiellement anti-âge et antioxydantes. Cependant, la manière dont elle affecte la peau chez l'homme est encore très peu étudiée. MÉTHODES: de la théophylline (10 ou 100 µM) a été ajoutée dans le milieu de culture d'un échantillon de peau humaine d'épaisseur totale ex vivo pendant 24 ou 72 h. RÉSULTATS: la théophylline a stimulé l'expression de la métallothionéine-1, une protéine antioxydante, et les taux d'ARNm du collagène I et III. L'évaluation immunohistologique de la fibrilline-1 a révélé une meilleure stabilité structurale des microfibrilles du derme. La théophylline a également exercé des effets protecteurs sur la matrice extracellulaire en diminuant les taux d'ARNm des métalloprotéinases matricielles MMP-2 et MMP-9, neutralisant en partie les effets de la ménadione, puissant donneur d'espèces réactives de l'oxygène (ROS) toxiques. En outre, elle a diminué l'apoptose des kératinocytes épidermiques stimulés par la ménadione. Fait intéressant, la théophylline a également augmenté le taux de mélatonine produite de manière intra-cutanée, la mélatonine étant le plus puissant neuromédiateur protecteur contre les ROS et réparateur des lésions de l'ADN. Elle a augmenté de façon tendancielle l'expression de la protéine MT1, récepteur de la mélatonine. La théophylline a également augmenté l'expression de la kératine 15, marqueur de cellules souches, dans la couche basale épidermique, mais n'a pas modifié l'activité mitochondriale ou la pigmentation épidermique. CONCLUSION: cette étude pilote ex vivo réalisée sur de la peau humaine montre que la théophylline a plusieurs propriétés protectrices de la peau complexes et intéressantes. Ces résultats encouragent à poursuivre l'étude de la théophylline en tant que candidat à un traitement local anti-âge.

What causes alopecia areata?

The pathobiology of alopecia areata (AA), one of the most frequent autoimmune diseases and a major unsolved clinical problem, has intrigued dermatologists, hair biologists and immunologists for decades. Simultaneously, both affected patients and the physicians who take care of them are increasingly frustrated that there is still no fully satisfactory treatment. Much of this frustration results from the fact that the pathobiology of AA remains unclear, and no single AA pathogenesis concept can claim to be universally accepted. In fact, some investigators still harbour doubts whether this even is an autoimmune disease, and the relative importance of CD8(+) T cells, CD4(+) T cells and NKGD2(+) NK or NKT cells and the exact role of genetic factors in AA pathogenesis remain bones of contention. Also, is AA one disease, a spectrum of distinct disease entities or only a response pattern of normal hair follicles to immunologically mediated damage? During the past decade, substantial progress has been made in basic AA-related research, in the development of new models for translationally relevant AA research and in the identification of new therapeutic agents and targets for future AA management. This calls for a re-evaluation and public debate of currently prevalent AA pathobiology concepts. The present Controversies feature takes on this challenge, hoping to attract more skin biologists, immunologists and professional autoimmunity experts to this biologically fascinating and clinically important model disease.

Is thyrotropin-releasing hormone a novel neuroendocrine modulator of keratin expression in human skin?

BACKGROUND: Hair and epithelial keratins constitute the major structural components of the skin and its appendages, including the hair fibre. While it is appreciated that selected steroid hormones regulate specific keratins, little is known about the neuroendocrine control of human hair keratin expression. Preliminary evidence had suggested that thyrotropin-releasing hormone (TRH) may regulate keratin gene transcription. OBJECTIVES: To clarify whether TRH operates as a novel neuroendocrine regulator of human hair and epithelial keratin expression under physiologically relevant conditions in situ. METHODS: Microdissected human female scalp hair follicles (HFs) and female scalp skin were treated in serum-free organ culture for 12 h to 6 days with 100 ng mL(-1) TRH or vehicle. Both quantitative immunohistomorphometry and quantitative real-time polymerase chain reaction were utilized to assess expression of selected keratins. RESULTS: TRH significantly increased expression of the hair keratins K31 and K32, while that of K85 and K86, and of the epithelial keratins K14 and K17, was reduced. In the interfollicular epidermis, TRH stimulated expression of K6, K14 and K17, both at the mRNA and protein levels. Stimulation of the same keratins was also evident in the eccrine sweat and sebaceous glands. CONCLUSIONS: Selected human hair and epithelial keratins are modulated in situ. This may be relevant to explain hair shaft growth-promoting effects of TRH. Our pilot study suggests that the neuroendocrine controls that regulate the expression of human keratins deserve more systematic exploration and that these may be harnessed therapeutically.

A randomized, double-blind, placebo- and active-controlled, half-head study to evaluate the effects of platelet-rich plasma on alopecia areata.

BACKGROUND: Alopecia areata (AA) is a common autoimmune condition, causing inflammation-induced hair loss. This disease has very limited treatment possibilities, and no treatment is either curative or preventive. Platelet-rich plasma (PRP) has emerged as a new treatment modality in dermatology, and preliminary evidence has suggested that it might have a beneficial role in hair growth. OBJECTIVES: To evaluate the efficacy and safety of PRP for the treatment of AA in a randomized, double-blind, placebo- and active-controlled, half-head, parallel-group study. METHODS: Forty-five patients with AA were randomized to receive intralesional injections of PRP, triamcinolone acetonide (TrA) or placebo on one half of their scalp. The other half was not treated. Three treatments were given for each patient, with intervals of 1 month. The endpoints were hair regrowth, hair dystrophy as measured by dermoscopy, burning or itching sensation, and cell proliferation as measured by Ki-67 evaluation. Patients were followed for 1 year. RESULTS: PRP was found to increase hair regrowth significantly and to decrease hair dystrophy and burning or itching sensation compared with TrA or placebo. Ki-67 levels, which served as markers for cell proliferation, were significantly higher with PRP. No side-effects were noted during treatment. CONCLUSIONS: This pilot study, which is the first to investigate the effects of PRP on AA, suggests that PRP may serve as a safe and effective treatment option in AA, and calls for more extensive controlled studies with this method.

Thyrotropin-releasing hormone and oestrogen differentially regulate prolactin and prolactin receptor expression in female human skin and hair follicles in vitro.

BACKGROUND: Human skin and scalp hair follicles are both a nonclassical target and an extrapituitary source of prolactin (PRL), which is a potent hair growth modulator. However, how the expression of PRL and PRL receptor (PRLR) is regulated in human skin is unknown. OBJECTIVES: To investigate whether two key stimulators of pituitary PRL secretion, thyrotropin-releasing hormone (TRH) and oestrogen, also regulate cutaneous PRL and PRLR expression. METHODS: Female scalp skin and/or microdissected hair follicles were treated for 6 days in serum-free organ culture with oestrogen (100 nmol L(-1)), TRH (1-10 ng mL(-1), 3-30 nm) or vehicle control. Quantitative immunohistomorphometry of skin and hair follicle sections was complemented with quantitative polymerase chain reaction for PRL and PRLR in cultured hair follicles and/or female human outer root sheath (ORS) keratinocytes. RESULTS: Oestrogen treatment significantly upregulated PRL and PRLR immunoreactivity in selected skin and hair follicle compartments, at the gene and protein level (P < 0.05). TRH significantly increased PRL immunoreactivity and transcription in hair follicles (P < 0.05); however, while it also increased PRLR transcription in hair follicles, it downregulated PRLR immunoreactivity in the hair follicle ORS (P < 0.05). CONCLUSIONS: Our pilot study shows that two key endocrine controls of pituitary PRL secretion, oestrogen and TRH, also regulate PRL and PRLR expression in human skin. This provides novel insights into the regulation of extrapituitary PRL and PRLR expression, and invites exploration of oestrogen and TRH as novel therapeutic agents in the management of skin and hair diseases characterized by aberrant PRLR-mediated signalling.

The 'melanocyte-keratin' mystery revisited: neither normal human epidermal nor hair follicle melanocytes express keratin 16 or keratin 6 in situ.

BACKGROUND: Keratin family proteins are generally accepted as being restricted to epithelial cells. However, several studies have challenged this paradigm by reporting, for example, that melanoma cells can express keratins and that normal human epidermal melanocytes, which derive from the neural crest, express keratin 16 (K16) in situ. OBJECTIVES: We wished to confirm or refute that K16 and/or its intermediate filament partner, keratin 6 (K6), are expressed in normal human epidermal and/or hair follicle melanocytes in situ. METHODS: Cryosections of normal human scalp skin were subjected to highly sensitive double immunohistochemistry with specific antibodies against K16 or K6 and against the melanocyte-specific marker NKI/beteb (gp100). Immunoreactivity (IR) was visualized by conventional light microscopy and confocal fluorescence microscopy. RESULTS: Despite the use of different, high-sensitivity immunostaining methods, stringent positive and negative controls, and monospecific, well-characterized antikeratin antibodies, we could detect neither K16 nor K6 IR within intraepidermal or intrafollicular pigment cells of normal human scalp skin. Instead, NKI/beteb+ cells were found to be intimately embedded in foci of K16+ and/or K6+ keratinocytes, which might create the illusion of keratin expression by these cells. CONCLUSIONS: Human epidermal or hair follicle melanocytes do not express K16 and/or K6 while residing in their natural habitat.

Reduction of digital plantar pressure by debridement and silicone orthosis.

The lesser digits are frequent sites of elevated plantar pressure and ulceration in the diabetic foot. We sought to determine whether debridement of callus and the wearing of a custom molded digital orthosis could significantly reduce digital plantar pressure. Fourteen patients with distal digital callus were studied. For each patient, the toe with the highest plantar pressure was selected. A computerized pressure mat was used to record the plantar pressure before and after debridement with and without a moldable silicone digital orthosis. Mean peak plantar digital pressures before treatment were 2.80+/-0.7 kg/cm2 for the entire group. The digital orthosis alone reduced plantar pressure to a mean of 1.95+/-0.65 kg/cm2 p < 0.05. Treatment by debridement similarly reduced pressure to 1.99+/-0.76 kg/cm2 p < 0.05. The most effective reduction of pressure for all patients, as well as the most statistically significant, occurred when both treatments were given, with mean peak plantar pressure falling to 1.28+/-0.61 kg/cm2 p < 0.01. Debridement and custom molded digital orthoses alleviate distal digital plantar pressure. Since elevated plantar pressure increases the risk of neuropathic ulceration, these treatments should be considered in the prophylactic care of appropriate patients.