Androgen Receptor Accelerates Premature Senescence of Human Dermal Papilla Cells in Association with DNA Damage

The dermal papilla, located in the hair follicle, expresses androgen receptor and plays an important role in hair growth. Androgen/Androgen receptor actions have been implicated in the pathogenesis of androgenetic alopecia, but the exact mechanism is not well known. Recent studies suggest that balding dermal papilla cells exhibit premature senescence, upregulation of p16^INK4a, and nuclear expression of DNA damage markers. To investigate whether androgen/AR signaling influences the premature senescence of dermal papilla cells, we first compared frontal scalp dermal papilla cells of androgenetic alopecia patients with matched normal controls and observed that premature senescence is more prominent in the dermal papilla cells of androgenetic alopecia patients. Exposure of androgen induced premature senescence in dermal papilla cells from non-balding frontal and transitional zone of balding scalp follicles but not in beard follicles. Overexpression of the AR promoted androgen-induced premature senescence in association with p16^INK4a upregulation, whereas knockdown of the androgen receptor diminished the effects of androgen. An analysis of γ-H2AX expression in response to androgen/androgen receptor signaling suggested that DNA damage contributes to androgen/androgen receptor-accelerated premature senescence. These results define androgen/androgen receptor signaling as an accelerator of premature senescence in dermal papilla cells and suggest that the androgen/androgen receptor-mediated DNA damage-p16^INK4a axis is a potential therapeutic target in the treatment of androgenetic alopecia.     

Androgenetic alopecia: pathogenesis and potential for therapy

Androgenetic alopecia occurs in men and women, and is characterised by the loss of hair from the scalp in a defined pattern. Determining factors appear to be genetic predisposition coupled with the presence of sufficient circulating androgens. The prevalence of this condition is high (up to 50% of white males are affected by 50 years of age) and, although there are no serious direct health consequences, the loss of scalp hair can be distressing. Knowledge of the pathogenesis of androgenetic alopecia has increased markedly in recent years. Pre-programmed follicles on the scalp undergo a transformation from long growth (anagen) and short rest (telogen) cycles, to long rest and short growth cycles. This process is coupled with progressive miniaturisation of the follicle. These changes are androgen dependent, and require the inheritance of several genes. To date, only one of these genes, which encodes the androgen receptor (AR), has been identified. Of the many treatments available for androgenetic alopecia, only two (finasteride and minoxidil) have been scientifically shown to be useful in the treatment of hair loss. However, these therapies are variable in their effectiveness. Discovery of the involvement of the AR gene, and the identification of other genes contributing to the condition, might lead to the development of new and more effective therapies that target the condition at a more fundamental level.     

BMI and levels of zinc,copper in hair,serum and urine of Turkish male patients with androgenetic alopecia

ObjectiveMale pattern androgenetic alopecia is characterized by progressive hair loss from the scalp. It is known that imbalances of some trace elements play a role in the pathomechanism of many forms of alopecia. The aim of this study was to evaluate the levels of zinc and copper in hair, serum and urine samples of Turkish males with male pattern androgenetic alopecia and to compare with healthy controls.Material and methods116 males with male pattern androgenetic alopecia and 100 controls were involved in this study.ResultsLevels of zinc and copper in hair were decreased significantly in the patients (p < 0.05), although zinc and copper levels of serum and urine were not different between patients and controls (p > 0.05). Body mass index of patients were higher than control group. In addition, in the group with body mass index of 25 and lower zinc level in hair and urine, copper level in serum were significantly higher (p < 0.05). Body mass index was negatively correlated with hair zinc levels.ConclusionWe thought that decreased zinc and copper levels in hair may play a role in the etiology of male pattern androgenetic alopecia. In addition, obesity by making changes in the balance of the trace elements in hair, serum and urine may play a role in male pattern androgenetic alopecia. Hence, assessing the levels of trace elements in hair of male pattern androgenetic alopecia patients may be more valuable compared to serum and urine for treatment planning.     

Trace elements content and hormonal profiles in women with androgenetic alopecia

It is well-known that some trace element imbalances play a significant role in the pathomechanism of many forms of alopecia. Androgenetic alopecia, however, is a specific local sensitivity of hair follicle receptors to androgens. In a clinical and laboratory study, 153 women with androgenetic alopecia (AGA) and 32 control women were examined. In AGA patients telogen hair and vellus hair (miniaturization, D < 30 μm) significantly differed in frontal and parietal hair comparison with occipital area (20 ± 0.9% vs. 12 ± 0.5% and 33 ± 0.9% vs. 12 ± 0.6% respectively). In the AGA group levels of androstenedione and dihydrotestosterone were higher than in the control group. Hair elemental content, analyzed by ICP-MS, demonstrated a lowered Cu and Zn content in the frontal area in comparison to the occipital area. It is important to note, that the AGA patients with elevated levels of androstenedione and dihydrotestosterone presented an increased Cu content and decreased Mn, Se, Zn contents in the occipital area of scalp. The occipital level of Cu positively correlated with the concentration of free testosterone in the serum. A negative correlation between the Zn content in the occipital area and the dehydroepiandrosterone level in the blood was found. Unfortunately, a routine treatment course of AGA patients, including topical inhibitor of 5-alpha-reductase and minoxidil, had no effect on the Cu hair content in occipital and frontal areas. However, there were positive changes in the morphological structure and other trace element contents. These data led us to hypothesize a key role of Cu metabolism disturbances in the AGA onset, development of AGA, and potential pharmaceutical targets for the treatment of AGA.     

Topical minoxidil in the treatment of alopecia areata.

A modified double blind crossover study was performed to assess the effect of 1% topical minoxidil as compared with placebo in 30 patients with alopecia areata and alopecia totalis. The active preparation produced a highly significant incidence of hair regrowth. A cosmetically acceptable response was noted in 16 patients. No side effects were seen. The study confirmed that topical minoxidil will induce new hair growth in alopecia areata but that it is less likely to do so in more severe and extensive disease. Furthermore, patients with alopecia universalis and totalis may not respond at all. Nevertheless, as compared with other drugs minoxidil applied topically is relatively non-toxic, is easy to use, and has no systemic or local side effects.     

CRF receptor antagonist astressin-B reverses and prevents alopecia in CRF over-expressing mice

Corticotropin-releasing factor (CRF) signaling pathways are involved in the stress response, and there is growing evidence supporting hair growth inhibition of murine hair follicle in vivo upon stress exposure. We investigated whether the blockade of CRF receptors influences the development of hair loss in CRF over-expressing (OE)-mice that display phenotypes of Cushing''s syndrome and chronic stress, including alopecia. The non-selective CRF receptors antagonist, astressin-B (5 µg/mouse) injected peripherally once a day for 5 days in 4–9 months old CRF-OE alopecic mice induced pigmentation and hair re-growth that was largely retained for over 4 months. In young CRF-OE mice, astressin-B prevented the development of alopecia that occurred in saline-treated mice. Histological examination indicated that alopecic CRF-OE mice had hair follicle atrophy and that astressin-B revived the hair follicle from the telogen to anagen phase. However, astressin-B did not show any effect on the elevated plasma corticosterone levels and the increased weights of adrenal glands and visceral fat in CRF-OE mice. The selective CRF₂ receptor antagonist, astressin₂-B had moderate effect on pigmentation, but not on hair re-growth. The commercial drug for alopecia, minoxidil only showed partial effect on hair re-growth. These data support the existence of a key molecular switching mechanism triggered by blocking peripheral CRF receptors with an antagonist to reset hair growth in a mouse model of alopecia associated with chronic stress.     

MicroRNAs take part in pathophysiology and pathogenesis of Male Pattern Baldness

Male Pattern Baldness (MPB) or androgenetic alopecia is a common form of hair loss with androgens and genetics having etiological significance. Androgens are thought to pathophysiologically power on cascades of chronically dramatic alterations in genetically susceptible scalp dermal papillas, specialized cells in hair follicles in which androgens react, and finally resulting in a patterned alopecia. However, the exact mechanisms through which androgens, positive regulators of growth and anabolism in most body sites, paradoxically exert their effects on balding hair follicles, are not yet known. The role of microRNAs, a recently discovered class of non-coding RNAs, with a wide range of regulatory functions, has been documented in hair follicle formation and their deregulation in cancer of prostate, a target organ of androgens has also been delineated. Yet, there is a lack of knowledge in agreement with microRNAs’ contribution in pathophysiology of MPB. To investigate the role of microRNAs in pathogenesis of MPB, we selected seven microRNAs, predicted bioinformatically on a reverse engineering basis, from previously published microarray gene expression data and analyzed their expression in balding relative to non-balding dermal papillas. We found for the first time upregulation of four microRNAs (miR-221, miR-125b, miR-106b and miR-410) that could participate in pathogenesis of MPB. Regarding microRNAs’ therapeutic potential and accessibility of hair follicles for gene therapy, these microRNAs can be considered as good candidates for a new revolutionized generation of treatments.     

Pathobiology of androgenetic alopecia

Human hair morphogenesis is a dynamic process caused by the remodelling of the skin. Hair growth is cyclic in mammals consisting of three distinct stages: an active stage (anagen), a regressive stage (catagen), and a resting stage (telogen). One disorder in this process is gradual balding of the scalp called androgenetic alopecia. Little is known about the cell biological or molecular mechanisms involved and thus very little treatment is currently available. In this review we focus on the most significant parameters affecting hair growth which participate in baldness.     

Induction of transforming growth factor-beta 1 by androgen is mediated by reactive oxygen species in hair follicle dermal papilla cells

The progression of androgenetic alopecia is closely related to androgen-inducible transforming growth factor (TGF)-β1 secretion by hair follicle dermal papilla cells (DPCs) in bald scalp. Physiological levels of androgen exposure were reported to increase reactive oxygen species (ROS) generation. In this study, rat vibrissae dermal papilla cells (DP-6) transfected with androgen receptor showed increased ROS production following androgen treatment. We confirmed that TGF-β1 secretion is increased by androgen treatment in DP-6, whereas androgeninducible TGF-β1 was significantly suppressed by the ROSscavenger, N-acetyl cysteine. Therefore, we suggest that induction of TGF-β1 by androgen is mediated by ROS in hair follicle DPCs. [BMB Reports 2013; 46(9): 460-464]     

The hair follicle: a paradoxical androgen target organ

Androgens are the main regulator of normal human hair growth. After puberty, they promote transformation of vellus follicles, producing tiny, unpigmented hairs, to terminal ones, forming larger pigmented hairs, in many areas, e.g. the axilla. However, they have no apparent effect on the eyelashes, but can cause the opposite transformation on the scalp leading to the replacement of terminal hairs by vellus ones and the gradual onset of androgenetic alopecia. This paradox appears to be an unique hormonal effect. Hair follicles are mainly epithelial tissues, continuous with the epidermis, which project into the dermis. A mesenchyme-derived dermal papilla enclosed within the hair bulb at the base controls many aspects of follicle function. In the current hypothesis for androgen regulation, the dermal papilla is also considered the main site of androgen action with androgens from the blood binding to receptors in dermal papilla cells of androgen-sensitive follicles and causing an alteration of their production of paracrine factors for target cells e.g. keratinocytes. Studies of cultured dermal papilla cells from sites with different responses to androgens in vivo have confirmed the paradoxical responses. All dermal papilla cells from androgen-sensitive sites contain low capacity, high affinity androgen receptors. However, only some cells formed 5alpha-dihydrotestosterone, e.g. beard but not axillary cells, in line with hair growth in 5alpha-reductase deficiency. Incubation with androgens also stimulated the mitogenic capacity of beard cell media, but inhibited that produced by scalp cells. This suggests that the paradoxical differences are due to differential gene expression within hair follicles, presumably caused during embryogenesis.     

Noncicatrizing alopecias; with special reference to alopecia areata

Since the epochal work of Hamilton there has been general acceptance of the causal relationship of the male sex hormone, age and familial inheritance in development of male pattern baldness. Some of the medicaments used in recent years may cause a diffuse loss of scalp hair. Alopecia that accompanies disease states is probably due to generalized toxemia and disturbances in metabolism. Sometimes male pattern baldness occurs in physiologic states, as exemplified by diffuse hair loss occasionally in the postpartum period. Alopecia areata deserves a critical appraisal, since it may be evidence of underlying neuropsychotic states that need psychiatric diagnosis and treatment. The development of alopecia totalis or universalis in 50 per cent of the prepuberal cases of alopecia areata is of real significance, especially since so very few patients recover their normal scalp hair. The conclusions reached by the authors of two articles reporting on 368 cases of alopecia areata, alopecia totalis and alopecia universalis that the evidence is overwhelming against the malfunction of the endocrine glands as the cause of alopecia areata must be considered real contributions to our understanding of this condition.A few conditions simulate alopecia areata. Probably the ones which are seen most often are trichotillomania and patchy baldness caused by agents used in hair waving and straightening. Our findings in 22 cases of alopecia areata of a persistent inflammatory perivascular and perifollicular infiltrate, massive plugging of the ostia, disappearance of robust hair follicles and diminution in total number of hair follicles and sometimes fibrosis are not necessarily diagnostic of alopecia areata but seem to be very definitely characteristic. Treatment for alopecia areata is of little avail. At this time we do not recommend the general use of the corticosteroids despite the improvement of scalp appearance in the majority of instances in which the systemic administration of these hormones have been employed.     

NONCICATRIZING ALOPECIAS—With Special Reference to Alopecia Areata

Since the epochal work of Hamilton there has been general acceptance of the causal relationship of the male sex hormone, age and familial inheritance in development of male pattern baldness.Some of the medicaments used in recent years may cause a diffuse loss of scalp hair. Alopecia that accompanies disease states is probably due to generalized toxemia and disturbances in metabolism. Sometimes male pattern baldness occurs in physiologic states, as exemplified by diffuse hair loss occasionally in the postpartum period.Alopecia areata deserves a critical appraisal, since it may be evidence of underlying neuropsychotic states that need psychiatric diagnosis and treatment. The development of alopecia totalis or universalis in 50 per cent of the prepuberal cases of alopecia areata is of real significance, especially since so very few patients recover their normal scalp hair.The conclusions reached by the authors of two articles reporting on 368 cases of alopecia areata, alopecia totalis and alopecia universalis that the evidence is overwhelming against the malfunction of the endocrine glands as the cause of alopecia areata must be considered real contributions to our understanding of this condition.A few conditions simulate alopecia areata. Probably the ones which are seen most often are trichotillomania and patchy baldness caused by agents used in hair waving and straightening.Our findings in 22 cases of alopecia areata of a persistent inflammatory perivascular and perifollicular infiltrate, massive plugging of the ostia, disappearance of robust hair follicles and diminution in total number of hair follicles and sometimes fibrosis are not necessarily diagnostic of alopecia areata but seem to be very definitely characteristic.Treatment for alopecia areata is of little avail. At this time we do not recommend the general use of the corticosteroids despite the improvement of scalp appearance in the majority of instances in which the systemic administration of these hormones have been employed.     

Methods of hair loss evaluation in patients with endocrine disorders

Hair loss may accompany several endocrine disorders, including hypopituitarism, hypothyreosis, hyperthyreosis, hypoparathyroidism, diabetes mellitus, growth hormone deficiency, hyperprolactinaemia, polycystic ovary syndrome, SAHA syndrome, congenital adrenal hyperplasia, Cushing syndrome, or virilising tumours. Most patients with endocrine disorders present with diffuse non-scarring alopecia, such as anagen effluvium, telogen effluvium or androgenetic alopecia. Focal non-scarring alopecia, such as alopecia areata coexisting with autoimmune thyroiditis, is less frequent and scarring alopecia is a rare finding in patients with endocrine abnormalities. In some cases an endocrine disorder may be suspected based on dermatological findings during hair loss evaluation. Classic methods of hair evaluation include hair weighing, pull test, wash test, the trichogram, and histopathological examination. Newly developed non-invasive diagnostic techniques include the phototrichogram, trichoscan, trichoscopy, and reflectance confocal microscopy.     

FOLLICULAR LIPOSOMAL DELIVERY SYSTEMS

ABSTRACT

Traditionally, the prime pathway for the topical delivery of active agents across the skin was thought to be through intercellular routes and transcellular routes of the stratum corneum. However, alternative means such as via appenageal transport, i.e., follicular transport, is gaining more acceptances in the scientific community. Targeting specific sites of the hair follicle may represent a feasible therapeutic approach to skin diseases such as hair loss. It is therefore an object of this research to develop novel liposomal formulations for enabling the topical delivery of difficult-to-absorb agents for localized action, specifically to the hair follicles and sebaceous glands. We examined small and large molecules. The small molecule chosen was minoxidil, a known hair growth stimulator. The large molecular weight molecule was plasmid DNA encoded with interleukin-1 receptor antagonist protein (IL-1ra).     

A gene for hypotrichosis simplex of the scalp maps to chromosome 6p21.3

Hypotrichosis simplex of the scalp (HSS) is an autosomal dominant form of isolated alopecia causing almost complete loss of scalp hair, with onset in childhood. After exclusion of candidate regions previously associated with hair-loss disorders, we performed a genomewide linkage analysis in two Danish families and localized the gene to chromosome 6p21.3. This was confirmed in a Spanish family, with a total LOD score of 11.97 for marker D6S1701 in all families. The combined haplotype data identify a critical interval of 14.9 cM between markers D6S276 and D6S1607. Localization of the locus for HSS to 6p21.3 is a first step toward identification of the gene. The gene will give important insights into the molecular and cellular basis of hair growth on the scalp.     

Hairless and Wnt Signaling: Allies in Epithelial Stem Cell Differentiation

Nuclear receptors and Wnt signaling are both important regulators of developmental and physiological processes. Recent work linking these pathways in epithelial stem cell differentiation has come from studies analyzing the in vivo function of the nuclear receptor corepressor, Hairless (HR). The HR protein has long been suspected to regulate a stem cell-mediated process, hair cycling, as mutations in the Hr gene cause hair loss in both mice and men. The discovery that the HR protein is a nuclear receptor corepressor indicated that HR function in hair cycling is by regulating gene expression. A recent study revealed that HR represses expression of Wise, an inhibitor of Wnt signaling, leading to a model in which HR controls the timing of Wnt signaling required for hair cycling. Here we review these data, and provide new data showing that HR corepressor activity is essential for its in vivo function, and identify an additional putative Wnt inhibitor regulated by HR. This work complements previous studies demonstrating the role of Wnt signaling in epithelial stem cell differentiation.     

Follicular liposomal delivery systems

Traditionally, the prime pathway for the topical delivery of active agents across the skin was thought to be through intercellular routes and transcellular routes of the stratum corneum. However, alternative means such as via appenageal transport, i.e., follicular transport, is gaining more acceptances in the scientific community. Targeting specific sites of the hair follicle may represent a feasible therapeutic approach to skin diseases such as hair loss. It is therefore an object of this research to develop novel liposomal formulations for enabling the topical delivery of difficult-to-absorb agents for localized action, specifically to the hair follicles and sebaceous glands. We examined small and large molecules. The small molecule chosen was minoxidil, a known hair growth stimulator. The large molecular weight molecule was plasmid DNA encoded with interleukin-1 receptor antagonist protein (IL-1ra).     

Microsporum canis Infection in Three Familial Cases with Tinea Capitis and Tinea Corporis

We report a familial infection caused by Microsporum canis. The first two patients were a 30-year-old female and her son, a 5-year-old boy, who came in contact with a pet dog at a farm house. The boy then suffered from hair loss for 3 months. There were circular and patchy alopecia with diffuse scaling on his scalp. Meanwhile, his mother also developed patchy erythema and scaling on her face. Several weeks later, the boy’s sister, a 4-year-old girl, was noted to have inconspicuous scaly plaques in the center of her scalp. The development of tinea capitis in the two children and tinea corporis in their mother were diagnosed based on the positive KOH examination. Morphologic characteristics and sequencing of the internal transcribed spacers 1 and 2, amplified from primary culture isolates, confirmed that their infections were caused by the zoophilic M. canis. Repetitive sequence-based molecular typing using the DiversiLab system secreted enzymatic activity analysis, and antifungal susceptibility indicated that these isolates might share the same source. The boy and girl were cured by the treatment with oral itraconazole and topical naftifine–ketoconazole cream after washing the hair with 2 % ketoconazole shampoo, and their mother was successfully treated by terbinafine orally in combination with topical application of naftifine–ketoconazole cream.     

Laminin-10 is crucial for hair morphogenesis

The role of the extracellular matrix in cutaneous morphogenesis is poorly understood. Here, we describe the essential role of laminin-10 (alpha5beta1gamma1) in hair follicle development. Laminin-10 was present in the basement membrane of elongating hair germs, when other laminins were downregulated, suggesting a role for laminin-10 in hair development. Treatment of human scalp xenografts with antibodies to laminin-10, or its receptor beta1 integrin, produced alopecia. E16.5 Lama5 -/- mouse skin, lacking laminin-10, contained fewer hair germs compared with controls, and after transplantation, Lama5 -/- skin showed a failure of hair germ elongation followed by complete hair follicle regression. Lama5 -/- skin showed defective basement membrane assembly, without measurable increases in anoikis. Instead, Lama5 -/- skin showed decreased expression of early hair markers including sonic hedgehog and Gli1, implicating laminin-10 in developmental signaling. Intriguingly, treatment of Lama5 -/- skin with purified laminin-10 corrected basement membrane defects and restored hair follicle development. We conclude that laminin-10 is required for hair follicle development and report the first use of exogenous protein to correct a cutaneous developmental defect.     

The use of micrografts and minigrafts in the aesthetic reconstruction of the face and scalp

Hair transplantation by use of micrografts (one- to two-hair follicular unit grafts) and minigrafts (three- to four-hair follicular unit grafts) used in large numbers (>1000 grafts) in a single session was initially described for the treatment of male pattern baldness. More recently, the author has found many other applications, particularly in facial and scalp reconstruction. The most common causes for aesthetic hair restoration of those areas in the author's experience include hair loss resulting from aesthetic facial rejuvenation surgery, revision of unsatisfactory results from previous hair transplantation, burn alopecia, congenital reasons, and hair loss after oncologic resections. The basic technique is described in detail, with variations given for each of the challenging anatomic areas, including the sideburns and temporal hairline, eyebrows, eyelashes, mustache, beard, and remaining scalp. Special attention is given to the direction of hair growth, hair texture, aesthetic planning, and absence of detectable scars, in order to mimic nature and to result in a minimal number of procedures. The use of micrografts and minigrafts in the aesthetic reconstruction of the face and scalp has been found to be safe and predictable, and has provided a high level of patient satisfaction.