Pro-inflammatory cytokine cascade in human plucked hair

Association between androgenetic alopecia and periodontitis

AIM

Androgenic alopecia (AGA) is men's most common form of hair loss. It is affected by changes in the expression and activity of 5αR and the metabolism of testosterone and DHT. There is an association between AGA and systemic inflammatory diseases. We hypothesized that there is an association between AGA and periodontal disease, as inflamed gingiva and periodontal fibroblasts have been shown to express more 5αR. Thus, this study aimed to evaluate the relationship between periodontal disease and AGA and the potential effect of aging on this association.

MATERIALS AND METHODS

Out of a cohort of 1088 individuals, 385 white males aged 25-65 with similar socioeconomic levels and without systemic disease were included. Periodontitis was defined using NHANES data. AGA was evaluated using the Norwood-Hamilton scale. The relationship between AGA, periodontal disease severity, and age was assessed.

RESULTS

There was a correlation between age and baldness (r = .421, p < .001). There was a significant correlation between AGA and periodontal disease in younger patients aged 25-34 and 35-44. (p < .042 and p < .036, respectively). There was no significant correlation between AGA and periodontal disease in the 45-54 and 55-65 age groups (p > .05).

CONCLUSION

There may be a relationship between periodontal disease and AGA in the 25-44 age range, suggesting that this association starts at an early age in adulthood.

Effects of some medicinal plant extracts on dermal papilla cells

INTRODUCTION

Miniaturization of the hair follicles is evident on the balding scalp. Approved medications, topical minoxidil, and oral finasteride for the treatment of alopecia sometimes come with undesirable adverse effects. The study was to examine the bioactivity of medicinal plants for finding the promising source of anti-hair loss application.

METHODS

Ten ethanolic extracts were prepared from Acacia concina (Willd.) DC., Acanthus ebracteatus Vahl, Bridelia ovata Decne, Cleome viscosa L., Cocos nucifera L., Hibiscus subdariffla L., Oryza sativa L., Terminalia chebula Retz., Tinospora crispa (L.) Hook. f. & Thomson and cytotoxic tested on dermal papilla cells using MTT assay. The effect of the extracts on cell cycle was also determined using flow cytometry technique. Anti-inflammatory activity was examined by determining IL-1β inhibition in RAW 257.4 cells. In vitro study of androgenic and 5α-reductase inhibitory activities were also determined using MTT assay and enzymatic reaction couple with liquid chromatography-mass spectrometry (LC-MS), respectively.

RESULTS

Our results revealed that only A. ebracteatus promoted dermal papilla cell proliferation and the S and G2/M phases in cell cycle. A. ebracteatus also showed inhibitory activity against 5α-reductase and testosterone in reducing cell viability of the dermal papilla. Moreover, A. ebracteatus extract strongly inhibited LPS-stimulating IL-1β production in RAW 264.7 cells in a dose-dependent manner.

CONCLUSION

Our finding indicated that the ethanolic extract of A. ebracteatus is a promising candidate for anti-hair loss treatment.

Effects of Acanthus ebracteatus Vahl. extract and verbascoside on human dermal papilla and murine macrophage

Androgenic alopecia is a common type of hair loss, usually caused by testosterone metabolism generating dihydrotestosterone and hair follicular micro-inflammation. These processes induce dermal papilla cells to undergo apoptosis. Currently approved effective medications for alopecia are Finasteride, an oral 5α-reductase inhibitor, Minoxidil, a topical hair growth promoter, and Diclofenac, an anti-inflammatory agent, all of which, however, have several adverse side effects. In our study, we showed the bioactivity of Acanthus ebracteatus Vahl. (AE) extract performed by 95% ethanol, and verbascoside (VB), a biomarker of AE extract. Both AE extract and VB were studied for their effects on dermal papilla cell viability and the cell cycle by using MTT assay and flow cytometry. The effect of an anti-inflammatory activity of AE extract and VB on IL-1β, NO, and TNF-α, released from LPS induced RAW 264.7 cells, and IL-1α and IL-6 released from irradiated dermal papilla cells were detected using ELISA technique. The preventive effect on dermal papilla cell apoptosis induced by testosterone was determined by MTT assay. In controlled in vitro assays it was found that AE extract and VB at various concentrations induced dermal papilla cell proliferation which was indicated by an increase in the number of cells in the S and G2/M phases of the cell cycle. AE extract at 250 µg/mL concentration or VB at 62.50 µg/mL concentration prevented cell apoptosis induced by testosterone at a statistically significant level. In addition, both AE extract and VB greatly inhibited the release of pro-inflammatory cytokines from RAW 264.7 and dermal papilla cells. The release of IL-1β, TNF-α, and NO from RAW 264.7 cells, as well as IL-1α and IL-6 from dermal papilla cells, was also diminished by AE extract 250 µg/mL and VB 125 µg/mL. Our results indicate that AE extract and VB are promising ingredients for anti-hair loss applications. However, further clinical study is necessary to evaluate the effectiveness of AE extract and VB as treatment for actual hair loss.

Low-Level Light Therapy Downregulates Scalp Inflammatory Biomarkers in Men With Androgenetic Alopecia and Boosts Minoxidil 2% to Bring a Sustainable Hair Regrowth Activity

BACKGROUND AND OBJECTIVES

Low-level light therapies using visible to infrared light are known to activate several cellular functions, such as adenosine triphosphate and nitric oxide synthesis. However, few clinical observations report its biological consequences for skin and scalp homeostasis. Since scalp inflammation was recognized as a potential physiological obstacle to the efficacy of the reference hair regrowth drug Minoxidil in vivo and since perifollicular inflammation is the hallmark of about 50%-70% follicular units in androgenetic alopecia, we decided to investigate whether the anti-inflammatory activity of LLLT/GentleWaves® device were assigned to L'Oréal by Light BioScience L.L.C., Virginia Beach, VA (US) could enhance hair regrowth activity of Minoxidil.

STUDY DESIGN/MATERIALS AND METHODS

We conducted a first experimental clinical study on 64 men with androgenetic alopecia using LLLT/GentleWaves®, 590-nm predominant wavelength 70 seconds, specifically pulsed once per day, for 3 days, and we performed a whole-genome analysis of treated scalp biopsies. In a second clinical study, including 135 alopecic volunteers, we evaluated the hair regrowth activity in response to the upgraded LLLT/GentleWaves® device and Minoxidil.

RESULTS

In the first clinical study, whole-genome analysis of treated scalp biopsies showed downregulation of scalp inflammatory biomarkers, such as AP1/FOSB messenger RNA (mRNA) and mir21, together with the disappearance of CD69 mRNA, specific to scalp-infiltrating T cells of about 50% of the studied volunteers prior to the LLLT/GentleWaves® treatment. In the second clinical study, we observed that LLLT/GentleWaves® was able to boost the hair regrowth activity of a Minoxidil 2% lotion to the extent of the highest concentration (5%) in terms of efficacy, number of responders, and perceived performance.

CONCLUSIONS

Altogether, these observations suggest the potential benefit of LLLT/GentleWaves® as a noninvasive adjunctive technology for skin and scalp conditions, where a mild perifollicular inflammation is involved. Lasers Surg. Med. 2021. Copyright © 2021 Wiley Periodicals LLC.

Systemic dexpanthenol as a novel treatment for female pattern hair loss

BACKGROUND

There are only a few drugs that have been used for the treatment of female pattern hair loss (FPHL).

AIMS

Through use of the Dermatologic Life Quality Index (DLQI) and a modified hair growth questionnaire, we aimed to evaluate the effect of dexpanthenol (DXP) as a new option for FPHL.

METHODS

Women who received 500 mg intramuscular DXP weekly for FPHL were included in this study. They were evaluated in terms of DLQI and laboratory characteristics, before and after DXP treatment, and were examined with a modified hair growth questionnaire.

RESULTS

Overall satisfaction with the appearance of the hair was described by the patients as 57.1% " I am satisfied," 28.6% "I am very satisfied," and 14.3% "I am neutral (neither satisfied nor dissatisfied)." There was a statistical difference between the mean DLQI scores before and after DXP treatment (P < .001). No statistical difference was found in the laboratory characteristics of the patients before and after DXP treatment (P > 0.05). No side effect was reported during DXP treatment.

CONCLUSION

Dexpanthenol is a safe and novel drug that may increase the quality of life in patients with FPHL.

Female Pattern Hair Loss and Androgen Excess: A Report From the Multidisciplinary Androgen Excess and PCOS Committee

OBJECTIVE

To determine the current state of knowledge and provide evidence-based recommendations that could be valid for all specialists taking care of female pattern hair loss (FPHL), a common form of hair loss in women that is characterized by the reduction of hair density in the central area of the scalp, whereas the frontal hairline is generally well conserved.

PARTICIPANTS

An expert task force appointed by the Androgen Excess and PCOS Society, which included specialists from dermatology, endocrinology, and reproductive endocrinology.

DESIGN

Levels of evidence were assessed and graded from A to D. Peer-reviewed studies evaluating FPHL published through December 2017 were reviewed. Criteria for inclusion/exclusion of the published papers were agreed on by at least two reviewers in each area and arbitrated by a third when necessary.

CONCLUSIONS

(i) The term "female pattern hair loss" should be used, avoiding the previous terms of alopecia or androgenetic alopecia. (ii) The two typical patterns of hair loss in FPHL are centrifugal expansion in the mid scalp, and a frontal accentuation or Christmas tree pattern. (iii) Isolated FPHL should not be considered a sign of hyperandrogenism when androgen levels are normal. (iv) The assessment of patients with FPHL is primarily clinical. (v) In all patients with FPHL, assessment of a possible androgen excess is mandatory. Measurement of vitamin D, iron, zinc, thyroid hormones, and prolactin are optional but recommended. (vi) Treatment of FPHL should start with minoxidil (5%), adding 5α-reductase inhibitors or antiandrogens when there is severe hair loss or hyperandrogenism.

Proprietary Herbal Extract Downregulates the Gene Expression of IL-1α in HaCaT Cells: Possible Implications Against Nonscarring Alopecia

Background

Currently while, topical minoxidil and oral finasteride are the only medications approved in androgenetic alopecia (AGA), the cause oriented treatment and immunsupressive treatment are being performed in telogen effluvium (TE) and alopecia areata (AA) respectively. Considering the inflammatory factors in the pathogenesis of these three nonscarring alopecia forms, we have formulated a mixture for topical usage composed of six different herbal extracts (HE) which have already known antiinflammatory and antioxidant features.

Materials and Methods

In addition to performing the phytochemical analysis of HE, we detected the gene expression level of IL-1α, the crucial hair loss mediator, for the putative efficacy in nonscarring alopecia. Cell proliferation assay was performed by XTT reagent. After determination of non-cytotoxic concentration, HaCaT cells were treated with HE. RNA isolations were carried out from both non-treated and treated cell groups by using TRI-reagent. Gene expressions of IL-1α and as control GAPDH were determined by RT-qPCR analysis.

Results

Results were represented as “IL-1α/GAPDH Fold Change”. HE solution caused statistically significant downregulation of IL-1α gene expressions (p<0.0001), compared to untreated control cells. HE treatment ended up with 0.1900 fold change for IL-1α.

Conclusion

IL-1α is a direct growth inhibitory agent in hair follicles and an important actor in the pathogenesis of AGA , TE, and AA. Considering together the vitamins, flavonoids, and trace elements identified in the phytochemical analyses and downregulation of IL-1α in HaCaT cells, our HE may be an auxiliary agent in the therapy of these three nonscarring alopecia forms.

Minoxidil Downregulates Interleukin-1 Alpha Gene Expression in HaCaT Cells

Introduction:

Minoxidil has been used topically to stimulate hair growth for male androgenetic alopecia (AGA) for more than 3 decades. It is currently being used for female AGA and alopecia areata (AA) as well. Although much time has passed since its first use, our understanding of its mechanism of action is highly limited. Therefore, we examined the inflammatory properties of AGA and AA, two entities in which minoxidil is being used as a therapeutic agent. We investigated the in vitro expression levels of cytokine interleukin-1 alpha (IL-1α), a potent inhibitor of hair growth, in minoxidil-treated human keratinocyte (HaCaT) cells to determine whether this molecule exerts anti-inflammatory effects.

Materials and Methods:

Cellular proliferation was examined using the Cell Proliferation Kit II (XTT) reagent. After determining a noncytotoxic concentration, HaCaT cells were treated with minoxidil. RNA was isolated from both untreated and treated cells with TRI Reagent^®. Expression of the IL-1α gene was determined by reverse transcription quantitative polymerase chain reaction analysis and is reported relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH), which served as a control.

Results:

Results are presented as IL-1α/GAPDH fold change. Minoxidil treatment downregulated IL-1α expression by 0.3433-fold compared with untreated cells (P = 0.001).

Conclusion:

This anti-inflammatory effect of minoxidil, as evidenced by significant downregulation of IL-1α gene expression in HaCaT cells, may represent one of its mechanisms of action in alopecia.

Advances in Understanding Hair Growth

In this short review, I introduce an integrated vision of human hair follicle behavior and describe opposing influences that control hair follicle homeostasis, from morphogenesis to hair cycling. The interdependence and complementary roles of these influences allow us to propose that the hair follicle is a true paradigm of a "Yin Yang" type, that is a cold/slow-hot/fast duality. Moreover, a new promising field is emerging, suggesting that glycans are key elements of hair follicle growth control.

Plucked human hair shafts and biomolecular medical research

The hair follicle is a skin integument at the boundary between an organism and its immediate environment. The biological role of the human hair follicle has lost some of its ancestral importance. However, an indepth investigation of this miniorgan reveals hidden complexity with huge research potential. An essential consideration when dealing with human research is the awareness of potential harm and thus the absolute need not to harm—a rule aptly qualified by the Latin term “primum non nocere” (first do no harm). The plucked hair shaft offers such advantages. The use of stem cells found in hair follicles cells is gaining momentum in the field of regenerative medicine. Furthermore, current diagnostic and clinical applications of plucked hair follicles include their use as autologous and/or three-dimensional epidermal equivalents, together with their utilization as surrogate tissue in pharmacokinetic and pharmacodynamics studies. Consequently, the use of noninvasive diagnostic procedures on hair follicle shafts, posing as a surrogate molecular model for internal organs in the individual patient for a spectrum of human disease conditions, can possibly become a reality in the near future.

Inhibition of inflammatory gene expression in keratinocytes using a composition containing carnitine, thioctic Acid and saw palmetto extract

Chronic inflammation of the hair follicle (HF) is considered a contributing factor in the pathogenesis of androgenetic alopecia (AGA). Previously, we clinically tested liposterolic extract of Serenoa repens (LSESr) and its glycoside, β-sitosterol, in subjects with AGA and showed a highly positive response to treatment. In this study, we sought to determine whether blockade of inflammation using a composition containing LSESr as well as two anti-inflammatory agents (carnitine and thioctic acid) could alter the expression of molecular markers of inflammation in a well-established in vitro system. Using a well-validated assay representative of HF keratinocytes, specifically, stimulation of cultured human keratinocyte cells in vitro, we measured changes in gene expression of a spectrum of well-known inflammatory markers. Lipopolysaccharide (LPS) provided an inflammatory stimulus. In particular, we found that the composition effectively suppressed LPS-activated gene expression of chemokines, including CCL17, CXCL6 and LTB(4) associated with pathways involved in inflammation and apoptosis. Our data support the hypothesis that the test compound exhibits anti-inflammatory characteristics in a well-established in vitro assay representing HF keratinocyte gene expression. These findings suggest that 5-alpha reductase inhibitors combined with blockade of inflammatory processes could represent a novel two-pronged approach in the treatment of AGA with improved efficacy over current modalities.

Influence of interleukin-1α on androgen receptor expression and cytokine secretion by cultured human dermal papilla cells

Dermal papilla cells (DPC) control the growth character of the hair follicle through their elaboration of mitogenic factors and extracellular matrix components. Further, the dermal papilla is a primary site of androgen action in the hair follicle. Interleukin-1alpha (IL-1alpha) is prominent in skin wounding and inflammatory responses although regarded as a negative hair growth regulator. We studied the effect of IL-1alpha and the potent androgen 5alpha-dihydrotestosterone (DHT) on the expression of the androgen receptor (AR) and various factors secreted by cultured human temporal scalp DPC. IL-1alpha triggered cellular changes consistent with nuclear factor-kappaB pathway activation as well as reduced AR mRNA and protein expression levels for DHT-stimulated DPC. This cytokine also increased DPC supernatant keratinocyte growth factor (KGF), vascular endothelial growth factor (VEGF), IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF) concentrations. IL-1alpha did not influence DPC supernatant levels of transforming growth factor-beta1, a negative hair growth regulator. The stimulatory effect of IL-1alpha on DPC VEGF, GM-CSF, KGF, and IL-8 expression was also evident at the mRNA level for these cytokines. IL-1alpha also increased mRNA transcript levels of protease-nexin-1, a secreted serine protease inhibitor expressed in the dermal papilla of anagen-stage hair follicles. Although DHT did not affect supernatant cytokine concentrations, the androgen altered mRNA transcript levels of several factors for DPC co-stimulated with IL-1alpha. In consideration of its in vitro activity profile, IL-1alpha may be an important modifier of dermal papilla activity as well as potentially influence androgen-regulated gene expression in DPC.

Procyanidin Oligomers Counteract TGF-β1- and TGF-β2-Induced Apoptosis in Hair Epithelial Cells: An Insight into Their Mechanisms

Procyanidin oligomers are polyphenol compounds we have identified in apples and barley which have hair growth stimulant effects, and which are able to promote hair epithelial cell growth and induce anagen induction of the hair cycle in the in vivo murine model. For the purpose of examining the hair-growing mechanisms of procyanidin oligomers, we examined their relationship to the TGF-beta signal pathway, known to be a regulator of catagen induction, and the mitogen-activated protein kinase cascade linked to cell proliferation. Addition of TGF-beta(1) or TGF-beta(2) to hair epithelial cell cultures dose-dependently decreased cell growth and induced apoptosis; however, addition of procyanidin B-2 to the culture neutralized the growth-inhibiting effects of both TGF-beta(1) and TGF-beta(2) and protected the cells from apoptosis. The same effects were observed with procyanidin B-3. We confirmed that procyanidin B-2 upregulates the expression of MEK-1/2 in cultured murine hair epithelial cells. We speculate that the hair-growing activity of procyanidin oligomers is at least linked to their growth-promoting effects on hair epithelial cells that follow MEK activation and their protective action on TGF-beta(1)- or TGF-beta(2)-induced apoptosis that is assumed to trigger catagen induction in the hair cycle.

[The life of human hair follicle revealed]

The human hair follicle is a unique appendage which results from epithelio-mesenchymal interactions initiated around the 3rd month of development. This appendage has a very complex structure, with a dermal compartment and an epithelial compartment. The dermal compartment comprises the connective tissue sheath and the dermal papilla, both of which are irrigated by microvessels. The epithelial compartment is made of highly replicating matrix cells giving rise to three concentrical domains, namely the outer root sheath, the inner root sheath and the hair shaft. The pigmentation unit, responsible for hair color, is made of fully active melanocytes located on top of the dermal papilla. Altogether a hair follicle contains more than 20 different cell types, engaged in different differentiation pathways and/or interacting with each other. This complex appendage has a unique behavior in mammals since, after a hair production phase, it involutes in place before entering a resting phase after which it renews itself under a cyclical but stochastic way, out of a double reservoir of pluripotent stem cells able to also regenerate epidermis. For yet unknown reasons, this well ordered process can be disturbed, provoking alopecia. The pigmentation unit also renews itself under a cyclical way, out of a melanocyte progenitor reservoir which progressively declines with time, provoking the hair whitening process. Finally, the shape of the hair shaft is programmed from the bulb. What makes this appendage unique and fascinating is its high degree of autonomy, its incredibly complex though stable structure, the number of different cell types interacting under an equilibrated way and its potential of regeneration. It represents a true paradigm of tissue homeostasis, exemplifying in a small living cylinder all the fundamental laws of cell-cell and tissue interactions. This life is revealed in this short synthesis.

Female pattern hair loss and its relationship to permanent/cicatricial alopecia: a new perspective

Female pattern hair loss (FPHL) is a common hair disorder of the central scalp. The clinical change in hair density, related to a change in the hair cycle and miniaturization of the hair follicle, is generally considered to be potentially reversible. However, there is now evidence of a permanent hair loss that develops in a subset of women with FPHL. The presence of a perifollicular lymphohistiocytic infiltrate and fibrosis is seen without follicular drop-out in biopsies of women with FPHL and with a notable follicular drop-out in a cicatricial form of this condition (heretofore called cicatricial pattern hair loss) as well as in fibrosing alopecia in a pattern distribution, currently classified as a subset of lichen planopilaris. The potential relationship of these conditions as well as frontal fibrosing alopecia and central centrifugal cicatricial alopecia, two other conditions of permanent hair loss seen primary in women, is discussed.

The natural history of androgenetic alopecia

Androgenetic alopecia (AGA) is the most common cause of hair loss, affecting up to 80% of men and 50% of women in their lifetime. Genetic predisposition to the disease is well known but the responsible genes have not been identified. Polymorphism in the androgen receptor gene has been recently detected in AGA.(1) Although the role of androgens, and particularly dihydrotestosterone (DHT), in causing the disease has been established for a long time, the natural history of AGA is still not completely understood. This paper reviews recent data about natural progression of the disease, as well as factors that may interfere with its course and long-term prognosis.

EEMCO Guidance for the Assessment of Hair Shedding and Alopecia

Knowledge of the hair follicle anatomy and the dynamics of hair cycling is substantial. Recognizing the anagen, catagen and telogen phases as well as teloptosis and the hair eclipse phenomenon clearly characterizes the typical hair chronobiology. Physiological modulators include hormones, neuromediators, miscellaneous biomolecules, seasons, micro-inflammation and ageing. For individuals who present with the complaint of increased hair shedding or alopecia, a host of evaluation techniques are available in addition to history, physical examination and laboratory assessment. Various clinical hair techniques can help in assessing the efficacy of drugs and cosmetics on hair growth. The methods are quite similar to those used to establish a definite diagnosis in dermatological practice. Great strides have been made during the recent decades in the methodology of hair growth trials in dermatology and cosmetology. Clinical evaluations benefit from a few additional specific techniques that enhance the perception of hair (re-) growth, shedding and alopecia. These assessments include the determination of hair patterning and density that may be helped by the 'black-and-white felt' examination. Daily hair counts, the 'hair pull test' and the 'hair feathering test' are also available. Instrumental methods provide reliable quantitative information that is useful if there are adequate controls. Some photographic methods, the trichogram, hair weighing and variants of the hair growth window technique including the phototrichogram, videotrichogram and tractio-phototrichogram provide insight into the complexities of hair cycling and shedding. Skin biopsy is indicated for diagnostic purposes, especially when the hair loss is accompanied by scarring.

Hair keratin pattern in human hair follicles grown in vitro

The keratin family includes epithelial (soft) keratins and hair (hard) keratins, and can be divided into acidic type I and basic to neutral type II subfamilies. Recently, nine type I and six type II hair keratin genes have been characterized through the screening of a human PAC library. The expression of these genes in the hair follicle was determined in vivo and a combined catalog of acidic and basic hair keratins was established. In this study, we investigated the expression and localization of most of the human hair keratin members of both types in human hair grown in vitro. We show that in vitro growth of hair follicles for 10 days in complete William's E culture medium did not alter the expression pattern of hair keratins. Similarly to the in vivo situation, each hair keratin was localized in precise and discrete compartments of the follicle, ranging from the matrix to the upper cortex and/or the hair cuticle. This study shows that the increase in length of in vitro grown follicles was accompanied by the proper hair shaft keratinization process. It also shows that hair follicle integrity was maintained in vitro, both in terms of gross morphology and molecular organization despite the complexity of the keratin expression pattern.

Procyanidin B-3, isolated from barley and identified as a hair-growth stimulant, has the potential to counteract inhibitory regulation by TGF-beta1

With the aim of identifying natural products, which possess hair-growing activity, we examined more than 1000 plant extracts with respect to their growth-promoting effects on hair epithelial cells. We discovered intensive growth-promoting activity, about 140% relative to controls, in barley extract. Our strategy for identifying active compounds in barley extract involved subjecting it to column chromatography using HP-20 resin columns, an LH-20 resin column, and preparative high-performance liquid chromatography (HPLC) using an ODS column. The 60% (v/v) aqueous methanol eluted fraction from the HP-20 column and the 75% (v/v) aqueous methanol eluted fraction from the subsequent LH-20 column showed high hair-growing activity in vivo. We isolated two major substances from the LH-20 active fraction using preparative HPLC. By means of mass spectrometry, 1H-NMR, and 13C-NMR analyses, one substance was revealed to be procyanidin B-3 and the other substance was identified as (+)-catechin. Purified procyanidin B-3 showed high hair-growing activity in the form of in vitro hair epithelial cell growth-promoting activity and in vivo anagen-inducing activity; however (+)-catechin showed no hair-growing activity. For the purpose of examining the hair-growing mechanisms of procyanidin B-3, we examined its relationship to the TGF-beta signal pathway, which is known to be a regulator of catagen induction. Addition of TGF-beta1 to hair epithelial cell cultures dose-dependently decreased the cell growth, and addition of procyanidin B-3 to the culture neutralized the growth-inhibiting effect of TGF-beta1. From these results, it is concluded that procyanidin B-3 can directly promote hair epithelial cell growth in vitro, has the potential to counteract the growth-inhibiting effect caused by TGF-beta1 in vitro, and has potential to stimulate anagen induction in vivo.

Tea tree oil reduces histamine-induced skin inflammation

BACKGROUND

Tea tree oil is the essential oil steam-distilled from Melaleuca alternifolia, an Australian native plant. In recent years it has become increasingly popular as an antimicrobial for the treatment of conditions such as tinea pedis and acne.

OBJECTIVES

To investigate the anti-inflammatory properties of tea tree oil on histamine-induced weal and flare.

METHODS

Twenty-seven volunteers were injected intradermally in each forearm (study and control assigned on an alternating basis) with histamine diphosphate (5 microg in 50 microL). Flare and weal diameters and double skin thickness were measured every 10 min for 1 h to calculate flare area and weal volume. At 20 min, 25 microL of 100% tea tree oil was applied topically to the study forearm of 21 volunteers. For six volunteers, 25 microL paraffin oil was applied instead of tea tree oil.

RESULTS

Application of liquid paraffin had no significant effect on histamine-induced weal and flare. There was also no difference in mean flare area between control arms and those on which tea tree oil was applied. However, mean weal volume significantly decreased after tea tree oil application (10 min after tea tree oil application, P = 0.0004, Mann-Whitney U-test).

CONCLUSIONS

This is the first study to show experimentally that tea tree oil can reduce histamine-induced skin inflammation.

Identification of clustered cells in human hair follicle responsible for MMP-9 gelatinolytic activity: consequences for the regulation of hair growth

BACKGROUND

The control of human hair follicle growth and differentiation is dependent upon several well-identified factors, including androgens, cytokines, and growth factors. In humans, alopecia androgenetica is a common aging process thought to be regulated through complex genetic imbalances, which also involve several of these crucial identified factors (and probably others not yet characterized), alone or in combination. Among these factors, epidermal growth factor (EGF), as well as pro-inflammatory cytokines, play a pivotal role, as evidenced by their direct inhibitory effects on hair growth both in vitro and in vivo. Following such treatments, the in vitro growth of hair follicles was rapidly arrested and deleterious modifications of hair morphology were also observed.

AIM

Because these cytokines act, at least partly, through the induction of matrix metalloproteinases (MMP), and because tissue remodeling occurs during the hair cycle, we attempted to identify and localize MMP in the human pilosebaceous unit.

METHOD

We used zymography to observe human hair follicles in culture in vitro.

RESULTS

We observed that human hair follicles in culture in vitro mainly and almost exclusively produce MMP-2 and MMP-9 gelatinolytic activities. Furthermore, after stimulation with EGF, tumor necrosis factor-alpha (TNF-alpha), or interleukin-1alpha (IL-1alpha), MMP-9 production was strongly increased. Using immunohistochemistry, we then precisely localized MMP-9 in the lower part of the inner root sheath (Henle's layer) of control human anagen hair follicles.

CONCLUSIONS

Cytokine- and EGF-induced upregulation of MMP-9 in the lower epithelial compartment of the human hair bulb is a major mechanism through which hair follicle involution, observed in alopecia, may occur.

Controls of hair follicle cycling

Nearly 50 years ago, Chase published a review of hair cycling in which he detailed hair growth in the mouse and integrated hair biology with the biology of his day. In this review we have used Chase as our model and tried to put the adult hair follicle growth cycle in perspective. We have tried to sketch the adult hair follicle cycle, as we know it today and what needs to be known. Above all, we hope that this work will serve as an introduction to basic biologists who are looking for a defined biological system that illustrates many of the challenges of modern biology: cell differentiation, epithelial-mesenchymal interactions, stem cell biology, pattern formation, apoptosis, cell and organ growth cycles, and pigmentation. The most important theme in studying the cycling hair follicle is that the follicle is a regenerating system. By traversing the phases of the cycle (growth, regression, resting, shedding, then growth again), the follicle demonstrates the unusual ability to completely regenerate itself. The basis for this regeneration rests in the unique follicular epithelial and mesenchymal components and their interactions. Recently, some of the molecular signals making up these interactions have been defined. They involve gene families also found in other regenerating systems such as fibroblast growth factor, transforming growth factor-beta, Wnt pathway, Sonic hedgehog, neurotrophins, and homeobox. For the immediate future, our challenge is to define the molecular basis for hair follicle growth control, to regenerate a mature hair follicle in vitro from defined populations, and to offer real solutions to our patients' problems.