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Hypoxia-inducible factors (HIFs) induce numerous genes regulating oxygen homeostasis. As oxygen sensors of the cells, the HIF prolyl 4-hydroxylases (HIF-P4Hs) regulate the stability of HIFs in an oxygen-dependent manner. During hair follicle (HF) morphogenesis and cycling, the location of dermal papilla (DP) alternates between the dermis and hypodermis and results in varying oxygen levels for the DP cells. These cells are known to express hypoxia-inducible genes, but the role of the hypoxia response pathway in HF development and homeostasis has not been studied. Using conditional gene targeting and analysis of hair morphogenesis, we show here that lack of Hif-p4h-2 in Forkhead box D1 (FoxD1)-lineage mesodermal cells interferes with the normal HF development in mice. FoxD1-lineage cells were found to be mainly mesenchymal cells located in the dermis of truncal skin, including those cells composing the DP of HFs. We found that upon Hif-p4h-2 inactivation, HF development was disturbed during the first catagen leading to formation of epithelial-lined HF cysts filled by unorganized keratins, which eventually manifested as truncal alopecia. Furthermore, the depletion of Hif-p4h-2 led to HIF stabilization and dysregulation of multiple genes involved in keratin formation, HF differentiation, and HIF, transforming growth factor β (TGF-β), and Notch signaling. We hypothesize that the failure of HF cycling is likely to be mechanistically caused by disruption of the interplay of the HIF, TGF-β, and Notch pathways. In summary, we show here for the first time that HIF-P4H-2 function in FoxD1-lineage cells is essential for the normal development and homeostasis of HFs., Competing Interests: Conflict of interest J. M. reports that financial support was provided by FibroGen, Inc and also reports a relationship with FibroGen, Inc that includes equity or stocks. All other authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background and Objective: Work has already been done on validating the cross-cultural adaptation of the Hair-Specific Skindex-29 questionnaire (HSS-29) into Spanish. This questionnaire measures the impact of female-pattern hair loss on health-related quality of life (HRQoL). The aim of this study was to complete the validation process by testing the questionnaire's sensitivity to change and assessing its correlation with the generic 12-item Short-Form Health Survey (SF-12)., Material and Method: Patients who started treatment with a nutritional supplement that blocks the activity of 5-alpha-reductase were seen in two visits: a baseline visit and a follow-up visit at 6months. At each visit, hair loss severity was assessed by both investigators and patients via the Sinclair scale, evaluation of hair condition, and administration of HSS-29 and SF-12., Results: In total, 983 women with female-pattern hair loss participated in the study. The mean HSS-29 score decreased from 25.7±18.7 at baseline to 19.3±15.7 at follow-up and significant changes were also observed in the functioning, emotions, and symptoms domains. Changes in overall and subscale HSS-29 scores from baseline to follow-up were all significantly correlated with changes in SF-12 subscale scores. The Pearson correlation coefficients ranged from -0.1 to -0.4 and were all significant at P<.001., Conclusions: The Spanish version of HSS-29 is sensitive to change, as it detected changes in objective measurements of HRQoL. Correlations between HSS-29 and SF-12 scores were also observed., (Copyright © 2019 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.)

Cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathyis a rare form of inherited cerebral small vessel disease associated with mutations in the high-temperature requirement serine peptidase A1 gene. As of now, only about 50 cases have been reported. In 2012, our group reported a family with a novel mutant of the high-temperature requirement serine peptidase A1 gene in China for the first time. To further explore the molecular pathogenesis of cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy, a recombination mouse model expressed human high-temperature requirement serine peptidase A1 gene mutant identified by our group was generated using the Donor & Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 system and termed the Mut-high-temperature requirement serine peptidase A1 gene L364P mouse model. Results show that Mut-high-temperature requirement serine peptidase A1 gene L364P mice present similar pathological characteristics to patients with cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy, suggesting that the Mut-high-temperature requirement serine peptidase A1 gene L364P mouse model was generated successfully. Moreover, apoptosis was induced in mouse brain vascular smooth muscle cells derived from Mut-high-temperature requirement serine peptidase A1 gene L364P mice. In summary, the cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy mouse model described in this study will be beneficial to demonstrate the pathological mechanism of cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy and provide new therapeutic targets for clinical treatment., Competing Interests: The authors declare that they have no competing interests, and all authors should confirm its accuracy., (©2019 Li et al. Published by IMR press. All rights reserved.)

Several studies have established that sulfotransferase enzyme activity in the outer root sheath of plucked hair follicles predicts response to topical minoxidil in the treatment of pattern hair loss. However, the prevalence of this enzyme activity among Indian patients has not been studied. Additionally, no reports in the literature characterize sulfotransferase activity based on sex, age, duration of hair loss, grade of hair loss, and family history. In this study we utilized a sulfotransferase activity assay first reported by Goren et al. We characterize the follicular sulfotransferase activity of 120 pattern hair loss patients visiting a dermatology outpatient clinic in India. Overall, 40.8% of patients with pattern hair loss had low levels of sulfotransferase. Surprisingly, 49.3% of men had low levels of sulfotransferase compared to 26.6% of women. No correlation was found between sulfotransferase activity and age, duration of hair loss, grade of hair loss, or family history. A sub-analysis of patient reported outcomes (PRO) validated previous findings that sulfotransferase enzyme activity is a predictive marker for minoxidil response in pattern hair loss patients., (© 2018 Wiley Periodicals, Inc.)

Lichen planopilaris (LPP) is an inflammatory cicatricial alopecia for which many different therapies are attempted with varying success. The Janus kinase (JAK) inhibitor, tofacitinib, has been shown to be effective in treating the noncicatricial alopecia, alopecia areata. As in alopecia areata, upregulation of interferon and JAK signaling may play a role in LPP. We retrospectively reviewed the cases of 10 patients with recalcitrant LPP who were treated with oral tofacitinib. Patients received oral tofacitinib 5 mg twice or three times daily for 2-19 months as either monotherapy or adjunctive therapy to other ongoing treatments including intralesional triamcinolone, hydroxychloroquine, and tacrolimus ointment. Eight patients had clinical improvement in LPP with tofacitinib as either monotherapy (4/10) or adjunctive therapy (4/10). LPP Activity Index (LPPAI) before and after treatment was measured in seven patients and was significantly different (6.22 before treatment, 3.08 after treatment; p value = .0014). Reduction in LPPAI ranged from 30 to 94%. One patient complained of 10 pound (4.5 kg) weight gain after 12 months on tofacitinib. No other adverse effects were reported. Treatment with oral tofacitinib either as monotherapy or adjunctive therapy can lead to measurable improvement in recalcitrant LPP., (© 2018 The Authors. Dermatologic Therapy published by Wiley Periodicals, Inc.)

Background: The potential of anti-aging effect of DPP-4 inhibitors is unknown. This study was performed to determine whether linagliptin, a DPP-4 inhibitor, could protect against premature aging in klotho-/- mice., Methods: Klotho-/- mice exhibit multiple phenotypes resembling human premature aging, including extremely shortened life span, cognitive impairment, hippocampal neurodegeneration, hair loss, muscle atrophy, hypoglycemia, etc. To investigate the effect of linagliptin on these aging-related phenotypes, male klotho-/- mice were divided into two groups: (1) control group fed the standard diet, and (2) linagliptin group fed the standard diet containing linagliptin. Treatment with linagliptin was performed for 4 weeks. The effect of linagliptin on the above mentioned aging-related phenotypes was examined., Results: Body weight of klotho-/- mice was greater in linagliptin group than in control group (11.1 ± 0.3 vs 9.9 ± 0.3 g; P < 0.01), which was associated with greater gastrocnemius muscle weight (P < 0.01) and greater kidney weight (P < 0.05) in linagliptin group. Thus, linagliptin significantly prevented body weight loss in klotho-/- mice. Survival rate of klotho-/- mice was greater in linagliptin group (93%) compared to control group (67%), although the difference did not reach statistical significance (P = 0.08). None of linagliptin-treated klotho-/- mice had alopecia during the treatment (P < 0.05 vs control klotho-/- mice). Latency of klotho-/- mice in passive avoidance test was larger in linagliptin group than in control group (P < 0.05), indicating the amelioration of cognitive impairment by linagliptin. Cerebral blood flow of klotho-/- mice was larger in linagliptin group than in control group (P < 0.01), being associated with greater cerebral phospho-eNOS levels (P < 0.05) in linagliptin group. Neuronal cell number in hippocampal CA1 region was greater in linagliptin group than in control group (P < 0.05). Linagliptin group had greater cerebral phospho-Akt (P < 0.05) and phospho-CREB (P < 0.05) than control group. Thus, linagliptin ameliorated brain aging in klotho-/- mice. The degree of hypoglycemia in klotho-/- mice was less in linagliptin group than in control group, as estimated by the findings of OGTT., Conclusions: Out work provided the evidence that DPP-4 inhibition with linagliptin slowed the progression of premature aging in klotho-/- mice, and provided a novel insight into the potential role of DPP-4 in the mechanism of premature aging.

This study aims to investigate the biological activities related to hair loss of Equisetum debile extracts, including 5α-reductase inhibition, interleukin-6 (IL-6) secretion reduction, and anti-oxidation. E. debile extracts were obtained by maceration in various solvents. Crude extract (CE) was obtained by maceration in 95% ethanol. Chlorophyll-free extract (CF) was the CE which of the chlorophyll has been removed by electrocoagulation. Hexane extract (HE), ethyl acetate extract (EA), and ethanolic extract (ET) were fraction extracts obtained from maceration in hexane, ethyl acetate, and 95% ethanol, respectively. The extracts were investigated for inhibitory activity against 5α-reductase and IL-6 secretion. Total phenolic contents (TPC) were investigated and antioxidant activities were determined by means of 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2'-diphenyl-1-picrylhydrazyl (DPPH), and ferric reducing antioxidant power (FRAP) assays. The inhibition of lipid peroxidation was determined by the ferric thiocyanate method. The cytotoxicity of the extracts on dermal papilla cells and irritation test by hen's egg test chorioallantoic membrane assay were also investigated. All extracts could inhibit 5α-reductase and decrease IL-6 secretion in lipopolysaccharide-stimulated macrophage. The antioxidant activity of E. debile extracts was directly related to their TPC. ET which contained the highest TPC (68.8 ± 6.7 mg GA/g) showed the highest equivalent concentration (EC₁) of 289.1 ± 26.4 mM FeSO₄/g, TEAC of 156.6 ± 34.6 mM Trolox/g, and 20.0 ± 6.0% DPPH inhibition. However, EA exhibited the highest inhibition against lipid peroxidation (57.2 ± 0.4%). In addition, EA showed no cytotoxicity on dermal papilla cell line and no irritation on chorioallantoic membrane of hen's eggs. In conclusion, EA was suggested as the most attractive ingredients for functional food and nutraceuticals because of the high inhibitory activity against 5α-reductase, IL-6 secretion, and lipid peroxidation inhibition., Competing Interests: The authors declare no conflict of interest.

Topical minoxidil is the only topical drug approved by the US Food and Drug Administration (FDA) for the treatment of androgenetic alopecia. However, the exact mechanism by which minoxidil stimulates anagen phase and promotes hair growth is not fully understood. In the late telegen phase of the hair follicle growth cycle, stem cells located in the bulge region differentiate and re-enter anagen phase, a period of growth lasting 2-6 years. In androgenetic alopecia, the anagen phase is shortened and a progressive miniaturization of hair follicles occurs, eventually leading to hair loss. Several studies have demonstrated that minoxidil increases the amount of intracellular Ca2+, which has been shown to up-regulate the enzyme adenosine triphosphate (ATP) synthase. A recent study demonstrated that ATP synthase, independent of its role in ATP synthesis, promotes stem cell differentiation. As such, we propose that minoxidil induced Ca2+ influx can increase stem cell differentiation and may be a key factor in the mechanism by which minoxidil facilitates hair growth. Based on our theory, we provide a roadmap for the development of a new class of drugs for the treatment of androgenetic alopecia.

The epidermis is the outermost layer of skin that acts as a barrier to protect the body from the external environment and to control water and heat loss. This barrier function is established through the multistage differentiation of keratinocytes and the presence of bioactive sphingolipids such as ceramides, the levels of which are tightly regulated by a balance of ceramide synthase and ceramidase activities. Here we reveal the essential role of alkaline ceramidase 1 (Acer1) in the skin. Acer1-deficient (Acer1(-/-) ) mice showed elevated levels of ceramide in the skin, aberrant hair shaft cuticle formation and cyclic alopecia. We demonstrate that Acer1 is specifically expressed in differentiated interfollicular epidermis, infundibulum and sebaceous glands and consequently Acer1(-/-) mice have significant alterations in infundibulum and sebaceous gland architecture. Acer1(-/-) skin also shows perturbed hair follicle stem cell compartments. These alterations result in Acer1(-/-) mice showing increased transepidermal water loss and a hypermetabolism phenotype with associated reduction of fat content with age. We conclude that Acer1 is indispensable for mammalian skin homeostasis and whole-body energy homeostasis. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland., (© 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.)

The efficacy of thiopurines, including azathioprine (AZA) and 6-mercaptopurine (6MP), has been demonstrated for the treatment of inflammatory bowel disease (IBD). The most common and serious adverse event of treatment with thiopurines altered by doctors is leukopenia. Hair loss is also a serious event that could be a critical reason for patients to decline thiopurine treatment. Thiopurine-induced severe hair loss causes cosmetic problems, and it takes a long time to recover. In a recent study, NUDT15 R139C was strongly associated with thiopurine-induced leukopenia in Korean and Caucasian populations. In this study, we performed an association study to investigate and replicate the association of R139C with adverse events of thiopurines in Japanese patients. A total of 142 Japanese patients with IBD, with histories of thiopurine treatment, were examined. NUDT15 R139C was genotyped using a custom TaqMan genotyping assay. Adverse events including leukopenia were reviewed from medical records. The 6MP dose was adjusted to AZA equivalents by multiplying with 2 as a thiopurine dose. Five patients developed severe hair loss and all of them were risk homozygous (T/T) for R139C. No early severe hair loss was observed in patients with the C/T or C/C genotype (P=3.82 × 10(-16), odds ratio=212). The association of R139C with early (<8 weeks) leukopenia (white blood cells<3000 mm(-3)), which was previously reported in Korean patients, was replicated in our Japanese IBD cohort (P=1.92 × 10(-16), odds ratio=28.4). However, we could not confirm the association with late leukopenia in the Japanese subjects. Patients with the C/T genotype discontinued treatment or required thiopurine dose reduction significantly earlier than patients with the C/C genotype (P=1.45 × 10(-4)); however, on manipulating the doses, there was no significant difference in the thiopurine continuation rates between the groups. In the maintenance period, the frequencies of 6MP usage were higher, and the doses of thiopurines were significantly lower in patients with the C/T genotype than in those with the C/C genotype (0.574±0.316 mg kg(-1) per day vs 1.03±0.425 mg kg(-1) per day, P=6.21 × 10(-4)). NUDT R139C was significantly associated with early severe hair loss in Japanese patients with IBD. We also verified the previously reported association of R139C with early leukopenia in a different East Asian population. It is recommended that treatment with thiopurines should be avoided for patients with the T/T genotype. Low-dose 6MP (0.2-0.3 mg kg(-1) per day) could be used rather than AZA for the patients with C/T genotype to continue thiopurine treatments. However, late leukopenia and other several adverse events could not be completely predicted by R139C genotypes.

Objective: To elucidate the molecular mechanism of mutant HTRA1-dependent cerebral small vessel disease in heterozygous individuals., Methods: We recruited 113 unrelated index patients with clinically diagnosed cerebral small vessel disease. The coding sequences of the HTRA1 gene were analyzed. We evaluated HTRA1 protease activities using casein assays and oligomeric HTRA1 formation using gel filtration chromatography., Results: We found 4 heterozygous missense mutations in the HTRA1 gene (p.G283E, p.P285L, p.R302Q, and p.T319I) in 6 patients from 113 unrelated index patients and in 2 siblings in 2 unrelated families with p.R302Q. The mean age at cognitive impairment onset was 51.1 years. Spondylosis deformans was observed in all cases, whereas alopecia was observed in 3 cases; an autopsied case with p.G283E showed arteriopathy in their cerebral small arteries. These mutant HTRA1s showed markedly decreased protease activities and inhibited wild-type HTRA1 activity, whereas 2 of 3 mutant HTRA1s reported in cerebral autosomal-recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) (A252T and V297M) did not inhibit wild-type HTRA1 activity. Wild-type HTRA1 forms trimers; however, G283E and T319I HTRA1, observed in manifesting heterozygotes, did not form trimers. P285L and R302Q HTRA1s formed trimers, but their mutations were located in domains that are important for trimer-associated HTRA1 activation; in contrast, A252T and V297M HTRA1s, which have been observed in CARASIL, also formed trimers but had mutations outside the domains important for trimer-associated HTRA1 activation., Conclusions: The mutant HTRA1s observed in manifesting heterozygotes might result in an impaired HTRA1 activation cascade of HTRA1 or be unable to form stable trimers., (© 2016 American Academy of Neurology.)

Five ceramide synthases (CerS2-CerS6) are expressed in mouse skin. Although CerS3 has been shown to fulfill an essential function during skin development, neither CerS6- nor CerS2-deficient mice show an obvious skin phenotype. In order to study the role of CerS4, we generated CerS4-deficient mice (Cers4-/-) and CerS4-specific antibodies. With these biological tools we analysed the tissue distribution and determined the cell-type specific expression of CerS4 in suprabasal epidermal layers of footpads as well as in sebaceous glands of the dorsal skin. Loss of CerS4 protein leads to an altered lipid composition of the sebum, which is more solidified and therefore might cause progressive hair loss due to physical blocking of the hair canal. We also noticed a strong decrease in C20 1,2-alkane diols consistent with the decrease of wax diesters in the sebum of Cers4-/- mice. Cers4-/- mice at 12 months old display additional epidermal tissue destruction due to dilated and obstructed pilary canals. Mass spectrometric analyses additionally show a strong decrease in C20-containing sphingolipids.

Avicennia marina (AM) exhibits various biological activities and has been traditionally used in Egypt to cure skin diseases. In this study, the methanolic heartwood extract of AM was evaluated for inhibitory activity against 5α-reductase (5α-R) [E.C.1.3.99.5], the enzyme responsible for the over-production of 5α-dihydrotestosterone (5α-DHT) causing androgenic alopecia (AGA). An AGA-relevant cell-based assay was developed using human hair dermal papilla cells (HHDPCs), the main regulator of hair growth and the only cells within the hair follicle that are the direct site of 5α-DHT action, combined with a non-radioactive thin layer chromatography (TLC) detection technique. The results revealed that AM is a potent 5α-R type 1 (5α-R1) inhibitor, reducing the 5α-DHT production by 52% at the final concentration of 10 µg/mL. Activity-guided fractionation has led to the identification of avicequinone C, a furanonaphthaquinone, as a 5α-R1 inhibitor with an IC50 of 9.94 ± 0.33 µg/mL or 38.8 ± 1.29 µM. This paper is the first to report anti-androgenic activity through 5α-R1 inhibition of AM and avicequinone C.

Topical minoxidil is the most common drug used for the treatment of androgenetic alopecia (AGA) in men and women. Although topical minoxidil exhibits a good safety profile, the efficacy in the overall population remains relatively low at 30-40%. To observe significant improvement in hair growth, minoxidil is typically used daily for a period of at least 3-4 months. Due to the significant time commitment and low response rate, a biomarker for predicting patient response prior to therapy would be advantageous. Minoxidil is converted in the scalp to its active form, minoxidil sulfate, by the sulfotransferase enzyme SULT1A1. We hypothesized that SULT1A1 enzyme activity in the hair follicle correlates with minoxidil response for the treatment of AGA. Our preliminary retrospective study of a SULT1A1 activity assay demonstrates 95% sensitivity and 73% specificity in predicting minoxidil treatment response for AGA. A larger prospective study is now under way to further validate this novel assay., (© 2013 Wiley Periodicals, Inc.)

Background: Effective, safe and well-tolerated therapeutic and/or preventive regimens for chemotherapy-induced alopecia (CIA) still remain to be developed. Because α-melanocyte-stimulating hormone (α-MSH) exerts a number of cytoprotective effects and is well tolerated, we hypothesized that it may be a candidate CIA-protective agent., Objectives: To explore, using a human in vitro model for chemotherapy-induced hair follicle (HF) dystrophy that employs the key cyclophosphamide metabolite (4-hydroperoxy-cyclophosphamide, 4-HC), whether α-MSH protects from 4-HC-induced HF dystrophy., Methods: Microdissected human scalp HFs from four individuals were treated with 4-HC, α-MSH and 4-HC plus α-MSH. Changes in HF cycling, melanin distribution and hair matrix keratinocyte proliferation/apoptosis were examined by quantitative (immune-) morphometry. Expression of the cytoprotective enzyme haem oxygenase-1 (HO-1) was determined by real-time reverse transcriptase-polymerase chain reaction in HF of two individuals., Results: In 50% of the individuals α-MSH reduced melanin clumping as an early sign of 4-HC-induced disruption of follicular pigmentation. α-MSH reduced 4-HC-induced apoptosis in the HFs of one female patient. These protective effects of α-MSH were not associated with changes in 4-HC-induced catagen induction. α-MSH and 4-HC both increased HO-1 mRNA expression, while the combination of both agents had additive effects on HO-1 transcription., Conclusions: Exogenous α-MSH exerts moderate HF-protective effects against 4-HC-induced human scalp HF damage and upregulates the intrafollicular expression of a key cytoprotective enzyme. However, as substantial interindividual response variations were found, further studies are needed to probe α-MSH as a candidate CIA-protective agent., (© 2013 British Association of Dermatologists.)

Background: Pattern (androgenetic) alopecia is commonly encountered in scalp biopsies obtained for non-scarring hair loss. Prostaglandin D-synthase is known to be elevated in bald vs. non-alopetic scalp of patients with androgenetic alopecia. We hypothesized that this difference in pattern of prostaglandin D-synthase expression may constitute a developmental pattern inherent to normal as well as alopecic scalp skin, thus defining a 'field' vulnerable to acquired hair loss., Methods: We immunohistochemically mapped prostaglandin D-synthase expression from supra-auricular to vertex scalp skin of 11 cadavers., Results: We found significantly more dermal mast cells immunoreactive for prostaglandin D-synthase in the vertex compared to the lateral aspects of the scalp, with a decrement that spatially approximated the pattern of androgenetic alopecia. This difference was present in both balding and non-balding scalps and was independent of gender. Dual labeling established dermal cells expressing prostaglandin D-synthase as mast cells., Conclusions: These data indicate that scalp is spatially programmed via mast cell prostaglandin D-synthase distribution in a manner reminiscent of the pattern seen in androgenetic alopecia., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

The site-2 protease (S2P) is an unusually-hydrophobic integral membrane protease. It cleaves its substrates, which are membrane-bound transcription factors, within membrane-spanning helices. Although structural information for S2P from animals is lacking, the available data suggest that cleavage may occur at or within the lipid bilayer. In mammalian cells, S2P is essential owing to its activation of the sterol regulatory element binding proteins (SREBPs); in the absence of exogenous lipid, cells lacking S2P cannot survive. S2P is also important in the endoplasmic reticulum (ER) stress response, activating several different membrane-bound transcription factors. Human patients harboring reduction-of-function mutations in S2P exhibit an array of pathologies ranging from skin defects to neurological abnormalities. Surprisingly, Drosophila melanogaster lacking S2P are viable and fertile. This article is part of a Special Issue entitled: Intramembrane Proteases., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Objective: Mutations in the high-temperature requirement A serine peptidase 1 (HTRA1) gene were studied in a Chinese family with cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL)., Methods: Exons 1-9 of the HTRA1 gene were amplified and bidirectionally sequenced in a Chinese family with CARASIL. Mutation effects were analysed by three-dimensional modelling of the serine protease HTRA1 protein., Results: The proband was found to be homozygous for a novel missense mutation (c.854 C > T) identified in exon 4 of the HTRA1 gene; the parents of the proband were heterozygous for the same missense mutation. This c.854 C > T mutation resulted in a change from proline to leucine (p.P285L) in serine protease HTRA1, and was absent in 260 control chromosomes. Three-dimensional models showed that the change from proline to leucine (p.P285L) could attenuate the hydrogen bond between S284 and S287 residues, which might affect function of serine protease HTRA1., Conclusion: Discovery of a novel missense mutation (c.854C>T) associated with CARASIL expands the known CARASIL-related mutations in HTRA1.

Testosterone is necessary for the development of male pattern baldness, known as androgenetic alopecia (AGA); yet, the mechanisms for decreased hair growth in this disorder are unclear. We show that prostaglandin D(2) synthase (PTGDS) is elevated at the mRNA and protein levels in bald scalp compared to haired scalp of men with AGA. The product of PTGDS enzyme activity, prostaglandin D(2) (PGD(2)), is similarly elevated in bald scalp. During normal follicle cycling in mice, Ptgds and PGD(2) levels increase immediately preceding the regression phase, suggesting an inhibitory effect on hair growth. We show that PGD(2) inhibits hair growth in explanted human hair follicles and when applied topically to mice. Hair growth inhibition requires the PGD(2) receptor G protein (heterotrimeric guanine nucleotide)-coupled receptor 44 (GPR44), but not the PGD(2) receptor 1 (PTGDR). Furthermore, we find that a transgenic mouse, K14-Ptgs2, which targets prostaglandin-endoperoxide synthase 2 expression to the skin, demonstrates elevated levels of PGD(2) in the skin and develops alopecia, follicular miniaturization, and sebaceous gland hyperplasia, which are all hallmarks of human AGA. These results define PGD(2) as an inhibitor of hair growth in AGA and suggest the PGD(2)-GPR44 pathway as a potential target for treatment.

Crude drugs expected to have an estrogenic effect were screened for their inhibitory activity on testosterone 5α-reductase. Testosterone 5α-reductase is an enzyme catalyzing the conversion of testosterone to dihydrotestosterone, which possesses high affinity for the androgen receptor. Among the crude drugs tested, we focused on Puerariae Flos (the flowers of Pueraria thomsonii) due to its potent inhibitory activity and suitability for commercial use. The 50% ethanolic extract of Puerariae Flos (PF-ext) showed inhibitory activity of 60.2% at 500 μg/ml against testosterone 5α-reductase. Interestingly, it was more potent than that of Puerariae Radix (roots of Pueraria lobata). PF-ext also showed in vivo anti-androgenic activity using a hair growth assay in testosterone-sensitive male C57Black/6NCrSlc strain mice. We demonstrated saponins, including soyasaponin I and kaikasaponin III, to be active components in PF-ext. In addition, hair growth promotion activity in C3H/He mice at 2 mg/mouse/day of the topical administration of PF-ext was demonstrated. Thus, Puerariae Flos is a promising crude drug for treating androgenic alopecia.

This research program on the novel functions of Panax ginseng C. A. Meyer focused on the effects of ginseng rhizome on hair re-growth in androgenetic alopecia. Extracts of red ginseng rhizome showed greater dose-dependent inhibitory effects against testosterone 5α-reductase (5αR) when compared with extracts of the main root. Ginsenoside Ro, the predominant ginsenoside in the rhizome, and ginsenoside Rg(3), a unique ginsenoside in red ginseng, showed inhibitory activity against 5αR with IC(50) values of 259.4 and 86.1 µm, respectively. The rhizome of P. japonicus, which contains larger amounts of ginsenoside Ro, also inhibited 5αR. Topical administration of extracts of red ginseng rhizomes (2 mg/mouse) and ginsenoside Ro (0.2 mg/mouse) to shaved skin inhibited hair re-growth suppression after shaving in the testosterone-treated C57BL/6 mice. These results suggest that red ginseng rhizomes containing both oleanane- and dammarane-type ginsenosides are a promising raw material for cosmetic use. This is the first report that ginsenoside Ro enhances in vivo hair re-growth based on their inhibitory activity against 5αR in the androgenetic alopecia model., (Copyright © 2011 John Wiley & Sons, Ltd.)

Although perturbed lipid metabolism can often lead to skin abnormality, the role of phospholipase A(2) (PLA(2)) in skin homeostasis is poorly understood. In the present study we found that group X-secreted PLA(2) (sPLA(2)-X) was expressed in the outermost epithelium of hair follicles in synchrony with the anagen phase of hair cycling. Transgenic mice overexpressing sPLA(2)-X (PLA2G10-Tg) displayed alopecia, which was accompanied by hair follicle distortion with reduced expression of genes related to hair development, during a postnatal hair cycle. Additionally, the epidermis and sebaceous glands of PLA2G10-Tg skin were hyperplasic. Proteolytic activation of sPLA(2)-X in PLA2G10-Tg skin was accompanied by preferential hydrolysis of phosphatidylethanolamine species with polyunsaturated fatty acids as well as elevated production of some if not all eicosanoids. Importantly, the skin of Pla2g10-deficient mice had abnormal hair follicles with noticeable reduction in a subset of hair genes, a hypoplasic outer root sheath, a reduced number of melanin granules, and unexpected up-regulation of prostanoid synthesis. Collectively, our study highlights the spatiotemporal expression of sPLA(2)-X in hair follicles, the presence of skin-specific machinery leading to sPLA(2)-X activation, a functional link of sPLA(2)-X with hair follicle homeostasis, and compartmentalization of the prostanoid pathway in hair follicles and epidermis.

Ichthyosis follicularis with atrichia and photophobia (IFAP syndrome) is a rare X-linked, oculocutaneous human disorder. Here, we assign the IFAP locus to the 5.4 Mb region between DXS989 and DXS8019 on Xp22.11-p22.13 and provide evidence that missense mutations exchanging highly conserved amino acids of membrane-bound transcription factor protease, site 2 (MBTPS2) are associated with this phenotype. MBTPS2, a membrane-embedded zinc metalloprotease, activates signaling proteins involved in sterol control of transcription and ER stress response. Wild-type MBTPS2 was able to complement the protease deficiency in Chinese hamster M19 cells as shown by induction of an SRE-regulated reporter gene in transient transfection experiments and by growth of stably transfected cells in media devoid of cholesterol and lipids. These functions were impaired in five mutations as detected in unrelated patients. The degree of diminished activity correlated with clinical severity as noted in male patients. Our findings indicate that the phenotypic expression of IFAP syndrome is quantitatively related to a reduced function of a key cellular regulatory system affecting cholesterol homeostasis and ability to cope with ER stress.

Retinoic acid (RA) is a potent signaling molecule that is essential for many biological processes, and its levels are tightly regulated by mechanisms that are only partially understood. The synthesis of RA from its precursor retinol (vitamin A) is an important regulatory mechanism. Therefore, the esterification of retinol with fatty acyl moieties to generate retinyl esters, the main storage form of retinol, may also regulate RA levels. Here we show that the neutral lipid synthesis enzyme acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1) functions as the major acyl-CoA:retinol acyltransferase (ARAT) in murine skin. When dietary retinol is abundant, DGAT1 deficiency results in elevated levels of RA in skin and cyclical hair loss; both are prevented by dietary retinol deprivation. Further, DGAT1-deficient skin exhibits enhanced sensitivity to topically administered retinol. Deletion of the enzyme specifically in the epidermis causes alopecia, indicating that the regulation of RA homeostasis by DGAT1 is autonomous in the epidermis. These findings show that DGAT1 functions as an ARAT in the skin, where it acts to maintain retinoid homeostasis and prevent retinoid toxicity. Our findings may have implications for human skin or hair disorders treated with agents that modulate RA signaling.

Background: Alopecia is a psychologically distressing condition. Androgenetic alopecia, which affects millions of men and women, is an androgen-driven disorder. Here, Cuscuta reflexa Roxb is evaluated for hair growth activity in androgen-induced alopecia., Methods: Petroleum ether extract of C. reflexa was studied for its hair growth-promoting activity. Alopecia was induced in albino mice by testosterone administration for 20 days. Its inhibition by simultaneous administration of extract was evaluated using follicular density, anagen/telogen ratio, and microscopic observation of skin sections. To investigate the mechanism of observed activity, in vitro experiments were performed to study the effect of extract and its major component on activity of 5alpha-reductase enzyme., Results: Petroleum ether extract of C. reflexa exhibited promising hair growth-promoting activity as reflected from follicular density, anagen/telogen ratio, and skin sections. Inhibition of 5alpha-reductase activity by extract and isolate suggest that the extract reversed androgen-induced alopecia by inhibiting conversion of testosterone to dihydrotestosterone., Conclusions: The petroleum ether extract of C. reflexa and its isolate is useful in treatment of androgen-induced alopecia by inhibiting the enzyme 5alpha-reductase.

trans-3,4'-Dimethyl-3-hydroxyflavanone (t-flavanone) is a synthetic compound with hair growth enhancing activity that is effective against male pattern alopecia. t-Flavanone was designed as a derivative of astilbin, the active hair growth enhancing component of Hypericum perforatum extracts. This study was designed to elucidate the mechanism of hair growth enhancement by t-flavanone. We investigated the effects of t-flavanone on transforming growth factor beta (TGF-beta), a known catagen-inducing factor induced in hair papilla cells by male hormone. When t-flavanone was added to cocultures of human hair papilla cells and human keratinocytes, there was no change in the total level of TGF-beta2. However, levels of active TGF-beta2 were reduced, suggesting the involvement of t-flavanone in the activation pathway of TGF-beta2. In order to investigate the effects of t-flavanone on TGF-beta2 activation by human keratinocytes, we evaluated the level of active TGF-beta2 converted from the inactive form in t-flavanone-treated human keratinocytes. The amount of active TGF-beta2 was reduced compared with controls suggesting that t-flavanone suppresses the TGF-beta2 activation cascade in human keratinocytes. We then examined the activity of urokinase-type plasminogen activator (uPA), the rate-limiting enzyme in the TGF-beta2 activation cascade, in t-flavanone-treated human keratinocytes. We found that t-flavanone reduces uPA activity on the keratinocyte surface. t-Flavanone is a hair growth enhancing component that has a novel mechanism of action which suppresses TGF-beta2 activation, and thereby is expected to have therapeutic effects on other types of alopecia in addition to male pattern alopecia.

Background: Male pattern hair loss (MPHL) is a potentially reversible condition in which dihydrotestosterone is an important etiologic factor., Objective: Our aim was to evaluate the efficacy of the type 1 and 2 5alpha-reductase inhibitor dutasteride in men with MPHL., Methods: Four hundred sixteen men, 21 to 45 years old, were randomized to receive dutasteride 0.05, 0.1, 0.5 or 2.5 mg, finasteride 5 mg, or placebo daily for 24 weeks., Results: Dutasteride increased target area hair count versus placebo in a dose-dependent fashion and dutasteride 2.5 mg was superior to finasteride at 12 and 24 weeks. Expert panel photographic review and investigator assessment of hair growth confirmed these results. Scalp and serum dihydrotestosterone levels decreased, and testosterone levels increased, in a dose-dependent fashion with dutasteride., Limitations: The study was limited to 24 weeks., Conclusion: Dutasteride increases scalp hair growth in men with MPHL. Type 1 and type 2 5alpha-reductase may be important in the pathogenesis and treatment of MPHL.

Three Alaskan malamutes with hair loss and slightly elevated blood concentrations of 17-hydroxyprogesterone after stimulation with adrenocorticotropic hormone (ACTH) were treated with trilostane. Trilostane, an inhibitor of 3 beta-hydroxysteroid dehydrogenase, was given twice daily at a dose of 3.0 to 3.6 mg/kg per day orally for 4 to 6 months. Routine ACTH stimulation tests were performed over 8 months to evaluate the degree of adrenal function suppression. Treatment with trilostane led to complete hair regrowth in all three dogs within 6 months. No adverse effects associated with trilostane were recognized.

We describe here a spontaneous, autosomal recessive mutant mouse suffering from skin and hair defects, which arose in the outbred Kunming strain. By haplotype analysis and direct sequencing of PCR products, we show that this mutation is a new allele of the asebia locus with a naturally occurring mutation in the Scd1 gene (a CCC insertion at nucleotide position 835 in exon 5), which codes for stearoyl-CoA desaturase 1. This mutation introduces an extra proline residue at position 279 in the Scd1 protein. The mutant mice, originally designated km/km but now assigned the name Scd1ab-Xyk (hereafter abbreviated as abXyk/abXyk), have a similar gross and histological phenotype to that reported for previously characterized allelic asebia mutations (Scd1ab, Scd1abJ, Scd1ab2J, and Scd1tm1Ntam). Histological analysis showed they were also characterized by hypoplasic sebaceous glands and abnormal hair follicles. In a cross between Kunming- abXyk/abXyk and ABJ/Le-abJ/abJ mice, all the progeny showed the same phenotype, indicating that the two mutations were non-complementing and therefore allelic. Comparisons with the other four allelic mutants indicate that the Scd1ab-Xyk mutation causes the mildest change in Scd1 function. This new mouse mutant is a good model not only for the study of scarring alopecias in humans, which are characterized by hypoplasic sebaceous glands, but also for studying the structure and function of the Scd1 protein.

Point mutations and deletions of mitochondrial DNA (mtDNA) accumulate in a variety of tissues during ageing in humans, monkeys and rodents. These mutations are unevenly distributed and can accumulate clonally in certain cells, causing a mosaic pattern of respiratory chain deficiency in tissues such as heart, skeletal muscle and brain. In terms of the ageing process, their possible causative effects have been intensely debated because of their low abundance and purely correlative connection with ageing. We have now addressed this question experimentally by creating homozygous knock-in mice that express a proof-reading-deficient version of PolgA, the nucleus-encoded catalytic subunit of mtDNA polymerase. Here we show that the knock-in mice develop an mtDNA mutator phenotype with a threefold to fivefold increase in the levels of point mutations, as well as increased amounts of deleted mtDNA. This increase in somatic mtDNA mutations is associated with reduced lifespan and premature onset of ageing-related phenotypes such as weight loss, reduced subcutaneous fat, alopecia (hair loss), kyphosis (curvature of the spine), osteoporosis, anaemia, reduced fertility and heart enlargement. Our results thus provide a causative link between mtDNA mutations and ageing phenotypes in mammals.

The role of 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated polyamine biosynthesis in the development of metastatic squamous cell carcinoma (mSCC) in protein kinase C epsilon (PKC epsilon) transgenic mice was determined. TPA treatment induced epidermal ornithine decarboxylase (ODC) activity and putrescine levels approximately 3-4-fold more in PKC epsilon transgenic mice than their wild-type littermates. Development of mSCC by the 7,12-dimethylbenz(a)anthracene (100 nmol)-TPA (5 nmol) protocol in PKC epsilon transgenic mice was completely prevented by administration of the suicide inhibitor of ODC alpha-difluoromethylornithine (DFMO, 0.5% w/v) in the drinking water during TPA promotion. However, DFMO treatment led to marked hair loss in PKC epsilon transgenic mice. DFMO treatment-associated hair loss in PKC epsilon transgenic mice was accompanied by a decrease in the number of intact hair follicles. These results indicate that TPA-induced ODC activity and the resultant accumulation of putrescine in PKC epsilon transgenic mice are linked to growth and maintenance of hair follicles, and the development of mSCC. Severe hair loss observed in PKC epsilon transgenic mice on DFMO during skin tumor promotion has not been reported before in the prevention of cancer in other animal models or in human cancer prevention trials.

For topical treatment of androgenetic alopecia (AGA) in women, solutions containing either estradiol benzoate, estradiol valerate, 17beta- or 17alpha-estradiol are commercially available in Europe and some studies show an increased anagen and decreased telogen rate after treatment as compared with placebo. At present it is not precisely known how estrogens mediate their beneficial effect on AGA-affected hair follicles. We have shown recently that 17alpha-estradiol is able to diminish the amount of dihydrotestosterone (DHT) formed by human hair follicles after incubation with testosterone, while increasing the concentration of weaker steroids such as estrogens. Because aromatase is involved in the conversion of testosterone to estrogens and because there is some clinical evidence that aromatase activity may be involved in the pathogenesis of AGA, we addressed the question whether aromatase is expressed in human hair follicles and whether 17alpha-estradiol is able to modify the aromatase activity. Herewith we were able to demonstrate that intact, microdissected hair follicles from female donors express considerably more aromatase activity than hair follicles from male donors. Using immunohistochemistry, we detected the aromatase mainly in the epithelial parts of the hair follicle and not in the dermal papilla. Furthermore, we show that in comparison to the controls, we noticed in 17alpha-estradiol-incubated (1 nM) female hair follicles a concentration- and time-dependent increase of aromatase activity (at 24 h: 1 nM = +18%, 100 nM = +25%, 1 micro M = +57%; 24 h: 1 nM = +18%, 48 h: 1 nM = +25%). In conclusion, our ex vivo experiments suggest that under the influence of 17alpha-estradiol an increased conversion of testosterone to 17beta-estradiol and androstendione to estrone takes place, which might explain the beneficial effects of estrogen treatment of AGA.

Significant evidence has accumulated suggesting that the inducible form of cyclooxygenase (COX-2), a central enzyme in the prostaglandin biosynthetic pathway, plays an important role in tumor development. To better understand the role of COX-2 in tumorigenesis, we generated transgenic mice that overexpress COX-2 under control of the human keratin 14 promoter, which allows for expression in the epidermis and some other epithelia. Transgenic mice, referred to as K14.COX2 mice, were readily distinguished from their nontransgenic littermates by the appearance of significant alopecia. Administration of a specific COX-2 inhibitor restored hair growth, indicating that the alopecia was attributable to elevated COX-2 enzymatic activity. Unexpectedly, COX-2 overexpression was found to protect, rather than sensitize, K14.COX2 mice to skin tumor development induced by an initiation/promotion protocol. K14.COX2 transgenics developed tumors at a much lower frequency than did their littermate controls (3.3% versus 93%, respectively, on a FVB background and approximately 25% versus 100%, respectively, on an ICR background) and presented with significantly reduced tumor burdens (average, 0.03 versus 12.7 tumors/mouse, respectively, on a FVB background and 0.5 versus 7.1 tumors/mouse, respectively, on an ICR background). Mice fed a COX-2 inhibitor in utero and as weanlings up to the time of promotion also showed a significant resistance to tumor development. These results clearly raise questions regarding the role of COX-2 and elevated prostaglandin levels in skin tumor development.

Background: A number of studies have provided evidence that apoptosis is a central element in the regulation of hair follicle regression. In androgenetic alopecia (AGA), the exact location and control of key players in the apoptotic pathways remains obscure., Objective: In the present study, we used a panel of antibodies and investigated the spatial and cellular pattern of expression of caspases and inhibitors of apoptosis (IAPs), such as XIAP and FLIP, in men with normal scalp and in men with AGA before and after 6 months of treatment with 1 mg oral finasteride treatment., Methods and Results: Constitutive expression of caspases-1, -3, -8, and -9 and XIAP was detected predominantly within the isthmic and infundibular hair follicle area, basilar layer of the epidermis, and eccrine and sebaceous glands. AGA-affected tissues showed an increase in caspase (-1, -3, -6, -9) immunoreactivity with a concomitant decrease in XIAP staining. After 6 months of finasteride treatment, both caspases and XIAP were similar to levels exhibited by normal subjects. Immunoblot analysis was performed to determine antibody specificity and cellular expression of caspases. Purified populations of keratinocytes, melanocytes, dermal papilla, and dermal fibroblasts derived from human hair follicles were cultured in vitro and treated with 0.5 mm staurosporin. Time-course experiments revealed that processing of caspase-3 is a principal event during apoptosis of these hair cell types., Conclusion: These data suggest that alterations in levels of caspases and IAPs regulate hair follicle homeostasis. Moreover, finasteride appears to influence caspase and XIAP expression in hair follicle cells thus signaling anagen, active growth in the hair cycle.

Finasteride has been shown to be an effective treatment for men with androgenetic alopecia (AGA) as it restores hair growth to miniaturized hair follicles on the top of the scalp [1]. Caspases are regulators of programmed cell death, and very likely some specific caspases may function as mediators of the hair growth cycle. It is unclear whether finasteride influences the regulation of apoptosis via caspases in the hair follicle. Very little information is available regarding the role of caspases present in human hair follicles in normal scalp and in androgenetic alopecia. In this study we have analyzed the family of caspases, 1-10 along with usurpin, and XIAP, in men with normal scalp and in men with androgenetic alopecia before and after 6 months treatment with 1 mg oral finasteride treatment. Caspases 1, 3, 8 and 9 were detected predominantly within the isthmic and infundibular hair follicle area for both normal and AGA patients, however the expression of all factors, especially caspase 3 was greater in the AGA group than in the normal scalp group. AGA men had the same caspase factors but with greater expression. In the same AGA men treated with finasteride for 6 months, the expression of these factors was similar to levels in the normal group. Results from our study indicate caspase 3 to be of primary importance in normal hair homeostasis and that DHT may be signaling greater expression of caspases, inducing apoptosis in androgenetic alopecia. In conclusion, DHT may selectively regulate the caspase genes which play an important role in signaling programmed cell death, affecting the hair growth cycle.

Androgenetic alopecia (AGA) is the most common type of hair loss in men and women. This continuous process results in a type of alopecia that follows a definite pattern in those individuals who are genetically predisposed. A genetic predisposition is a feature of AGA, but the predisposing genes are still unknown. Our understanding, however, of the hormonal effects on hair growth is far move advanced, and human hair follicles are not only targets for androgens, but also reveal an active androgen metabolism, with the ability to convert several androgens by different steroidogenic enzymes. Recent results suggest that the dermal papilla of the hair follicle expresses abundant type 2 5a-reductase, 3b-HSD and steroid sulfatase activity. Therefore, current information about the androgen metabolism in hair follicles is reviewed and the potential impact on future therapeutic approaches is discussed.

The gonadal synthesis of testosterone from cholesterol involves four enzymes, namely, cytochrome P-450 side-chain cleavage enzyme, cytochrome P-450 17a-hydroxylase/lyase, 3b-hydroxysteroid dehydrogenase, and 17b-hydroxysteroid dehydrogenase. A significant part of the plasma-borne testosterone is converted in androgen target tissues, such as the skin, to the more potent androgen dihydrotestosterone by the steroid 5a-reductase type 1 and type 2 isoenzymes. Dihydrotestosterone, which binds to the nuclear androgen receptor with much greater affinity than testosterone, is the androgen responsible for a process leading to androgenetic alopecia. Consequently, the 5a-reductase inhibitor finasteride was developed and has proven efficacious in promoting hair growth as a consequence of lowering scalp and plasma dihydrotestosterone levels. In contrast to the direct synthesis of dihydrotestosterone from testosterone, biologically inactive C19-steroids produced by glandular and peripheral tissues may also feed into the scalp skin production of dihydrotestosterone by the local expression of reductive 17b-hydroxysteroid dehydrogenase, oxidative 3a-hydroxysteroid dehydrogenase, and 3b-hydroxysteroid dehydrogenase enzymes. Aberrant expression of one or more of these enzymes, could conceivably result in increased scalp dihydrotestosterone levels, and possibly, acceleration of the balding process in genetically predisposed men and women.

Recent studies suggest that 5 alpha-reductase type 2 (5 alpha R2) rather than 5 alpha R1 plays a key role in the pathogenesis of male-pattern baldness. To clarify the localization of the androgen receptor (AR), 5 alpha R1, and 5 alpha R2 in the hair follicle, we investigated the expression of the corresponding genes by RT-PCR using microdissected hair follicles. AR and 5 alpha R1 mRNAs were expressed in all portions of the hair follicle. By contrast, 5 alpha R2 mRNA was expressed only in mesenchymal portions that included the dermal papilla and connective tissue sheath, and hardly any was expressed in epithelial portions. The intensity of expression of these genes in each portion of the hair follicles did not differ between follicles from balding and nonbalding scalp. We also examined the expression of these genes in cultured fibroblasts derived from the dermal papilla and connective tissue sheath. Although expression of AR and 5 alpha R1 mRNAs was easily detected, there was no obvious expression of 5 alpha R2 mRNA in either type of cell. Type-specific inhibition of 5 alpha R activity by MK386 and MK906 confirmed these patterns of expression of 5 alpha R mRNA. Thus, the expression of 5 alpha R2 mRNA seems to be characteristic of freshly microdissected mesenchymal portions of the hair follicle, but such expression might not be maintained in culture.

In establishing a theory to predict male-pattern baldness, we investigated the correlation of testosterone, epitestosterone, and dihydrotestosterone with 5alpha-reductase in hair using gas chromatography-mass spectrometry. One hundred milligram hair samples were obtained from a group of balding subjects and their sons, as well as from a corresponding aged-matched, nonbalding group. The ratio of testosterone to epitestosterone was significantly greater (mean 46.41, p < 0.001; mean 35.83, p < 0.001, respectively) in the hair of balding fathers (n = 19, age 28-50 y) and their sons (n = 16, age 8-16 y) than in the hair of the nonbalding control subjects (mean 9.17 and 10.47, respectively). These findings demonstrate that analysis of terminal hair may not only provide a basis for predicting baldness when the subject is still young, but also for preventing and treating male-pattern baldness by controlling the steroid hormone balance.

Activity of glucose-6-phosphate 1-dehydrogenase (G6PDH) in human hair follicles was measured. A good relationship has been demonstrated between the activity and the ratio of the number of the anagen hairs to that of all the plucked hairs in the frontal-parietal region of the scalp with male-pattern alopecia. As the ratio becomes lower so that the advancing degree of alopecia is higher, the G6PDH activity becomes lower.

The predominant form of 5alpha-reductase (5aR) in human scalp is 5aR1. None the less, clinical studies have shown that finasteride, a selective inhibitor of 5aR2, decreases scalp dihydrotestosterone and promotes hair growth in men with androgenetic alopecia. Immunolocalization studies were thus carried out to examine 5aR isozyme distribution within scalp and, in particular, to determine whether 5aR2 might be associated with hair follicles. 5aR2 was localized using both a rabbit polyclonal and a mouse monoclonal antibody. 5aR1 was detected with a mouse monoclonal antibody. The specificity of these reagents was demonstrated both by immunofluorescence and Western blot analyses of COS cells overexpressing human 5aR1 or 5aR2. When cryosections of scalp from men with androgenetic alopecia were stained with antibody against 5aR2, using immunoperoxidase avidin-biotin complex methodology, immunostaining was observed in the inner layer of the outer root sheath and, in more proximal regions of the follicle, in the inner root sheath. Staining was also prominent in the infundibular region of the follicle, with less intense staining extending throughout the granular layer of the epidermis. Some staining was also seen in sebaceous ducts. Similar results were obtained with both the polyclonal and monoclonal 5aR2 antibodies. In contrast, in scalp cryosections stained with antibody to 5aR1, no immunostaining was observed within hair follicles. Intense staining for the type 1 isozyme was, however, detected within sebaceous glands. Our immunolocalization data suggest that the results seen in clinical trials of men with male pattern hair loss treated with finasteride may be due, at least in part, to local inhibition of 5aR2 within the hair follicle.

Androgenetic alopecia is the most common form of hair loss in men and women. Although clinically different, the pathogenetic pathways leading to this type of hair loss are similar in both sexes. Recent experimental data enable us to explain some pathogenetic steps suggesting a pivotal role of type 2 5 alpha-reductase in the pathogenesis of androgenetic hair loss. In this review our current knowledge about the pathophysiology and treatment options of androgenetic alopecia is summarized.

Minoxidil is known to induce hair growth in male pattern baldness, for which development androgen plays a central role. We studied the effect of minoxidil on testosterone metabolism by cultured dermal papilla cells from balding or nonbalding scalp and dermal fibroblasts. In all three groups, 17beta-hydroxysteroid dehydrogenase activity was much higher than 5alpha-reductase activity. Minoxidil increased 17beta-hydroxysteroid dehydrogenase activity by nearly 40% (P < 0.001) in dermal papilla cells of balding scalp, whereas the effect was less marked in dermal papilla cells from nonbalding scalp and dermal fibroblasts. 5alpha-Reductase activity was also slightly increased by minoxidil in dermal papilla cells from balding scalp. Again, the effect on 5alpha-reductase activity was insignificant in the other two groups of cells. Whether such modification of testosterone metabolism in dermal papilla cells of balding scalp by minoxidil is related to its therapeutic effect remains unknown.