More on mast cells and dermal fibrosis

[bornthisway]

Dermal fibrosis in male pattern hair loss: a suggestive implication of mast cells.

Arch Dermatol Res. 2008 Mar;300(3):147-52. Epub 2008 Feb 20.

Won CH, Kwon OS, Kim YK, Kang YJ, Kim BJ, Choi CW, Eun HC, Cho KH.

Department of Dermatology, Seoul National University College of Medicine, Yongon-Dong 28, Chongno-Gu, Seoul, 110-744, Republic of Korea.

A relationship has been suggested between mast cells (MCs) and male pattern hair loss (MPHL), because of histological evidence of perifollicular fibrosis and increased mast cell numbers. Two paired punch biopsies were taken from balding vertexes and non-balding occipital promontory areas of ten patients with MPHL (Ludwig-Hamilton IIIv to IV) and from five normal subjects aged from 20 to 35 years. Masson trichrome and Victoria blue staining were performed to observe collagen frameworks and elastic fiber structures. Numbers of immunoreactive MCs stained with anti-tryptase or anti-chymase antibody were counted. It was found that collagen bundles were significantly increased in balding vertexes than in non-balding occiput scalp skin. A near 4-fold increase in elastic fibers was observed in both vertex and occiput scalp skins with MPHL versus controls. Total numbers of MCs (tryptase-positive) in site-matched scalp samples were about 2-fold higher in MPHL subjects than in normal controls. Percentage elastic fiber (%) was found to be relatively well-correlated with tryptase and chymase-positive MCs. These findings suggest that accumulated MCs might be responsible for increased elastic fiber synthesis in MPHL, and indicate that future investigations are warranted.

PMID: 18286292

 

[michael barry]

its downstream of TGF-beta. The dermal sheath in Androgenetic Alopecia is 2 to 2.5 times thicker with crosslinked collagen, making it hard for the follicle to enlarge. Streamers of collagen appear underneath the follicle over time. It looks just like organ rejection microscopially. TGF-beta plays a similar role in other autoimmune disorders.

What is the body reacting to? The first inflammation seen in Androgenetic Alopecia is in the upper infradfulindulum where hyperkeratinization is usually taking place. There are 5AR type one there and androgen receptors there. I see two possibilities: either DKK_1 downstream of the papilla is killing keratinocytes or hyperkeratinization from too much androgen stimulation is killing the keratinocytes and the dead keratinocyte cells still in the hair shaft that have not grown all the way out of the body are eliciting the immunological response. The inflammaition in Androgenetic Alopecia is in the upper one third of the follicle, not down in the papilla where you think it would be. Inflammation, as Harold pointed out, is like a bomb going off in the body. Tissues next to the effected tissue get hurt also. This is my opinion of course, but cannot figure out any other reason why the damge in androgenic alopeica is a "low" process. Classic autoimmune disorders see the effected tissue destroyed pretty damned fast (just a few years at most), not over a decade or two like men slowly balding with too much collagen secreted all around the organ as happens. Docj077 thought TGF beta was the primary culprit in baldness------I wish he still posted, he was bright.

 

[harold]

Will post the text of this study in a bit. First here is a cotsarelis study cited by this one that discusses a female patient with scarring alopecia who upon examination was found to have mastocytosis - too many mast cells. They implicate mast cells as being causative of the sort of fibrosis and scarring seen in male pattern baldness.
hh

"Abstract

Background: Mastocytosis is comprised of a group of heterogeneous diseases involving various organs. Urticaria pigmentosa is the most common manifestation of cutaneous mastocytosis; others include mastocytoma, diffuse mastocytosis, and telangiectasia macularis eruptiva perstans.

Methods: We describe a case of indolent mastocytosis presenting as scarring alopecia. The scalp biopsy revealed a perifollicular and dermal inflammatory infiltrate composed predominantly of mast cells, which was confirmed by tryptase and Giemsa stains.

Results: The preponderance of mast cells in the biopsy prompted testing for urine N-methylhistamine levels, which were elevated and confirmed the diagnosis of mastocytosis. This is the first report of mastocytosis presenting as scarring alopecia.

Conclusions: This case suggests that the diagnosis of mastocytosis should be entertained in patients presenting with scarring alopecia accompanied by an intense mast cell infiltrate on scalp biopsy and also supports the notion that mast cells may be involved in the pathogenesis of alopecia.

The most common manifestation of cutaneous mastocytosis is urticaria pigmentosa. It is seen in over 90% of patients with mastocytosis and in just under 50% of patients with mastocytosis associated with hematological disorders.1 Other skin lesions associated with mastocytosis include mastocytoma, diffuse mastocytosis, and telangiectasia macularis eruptiva perstans. These patients may also have systemic symptoms consistent with increased mast cell numbers and their inflammatory mediators. Classic lesions and a positive Darier's sign suggest the diagnosis of cutaneous mastocytosis. Skin biopsy and measurement of urinary histamine metabolites, such as N-methylhistamine, are generally necessary to confirm the diagnosis. Atypical presentations may resemble eruptive xanthomas, impetigo, Langerhans' cell histiocytosis, or may have constitutional symptoms similar to carcinoid syndrome. We describe the first case of indolent mastocytosis presenting as cicatricial alopecia.
Case report


The patient is a 63-year-old woman with a 6-year history of cicatricial alopecia. For 3 years prior to presentation, she had noticed a tightening of her scalp that was painful at times. She also described infrequent abdominal cramps and occasional episodic hot flashes for the last 9 years. She noted that she experienced severe insect-bite reactions that lasted for several weeks. Her medical history was significant only for a cardiac arrhythmia, which was present for the past 25 years.

On physical examination, the patient appeared well with gray-black hair and an irregularly shaped, asymmetrical area of scarring alopecia on the vertex and superior scalp (Fig. 1). The eyebrows, eyelashes, and axillary hair were uninvolved. The patient was not dermatographic. The remainder of the skin examination was unremarkable without any evidence of lesions typical for urticaria pigmentosa. Laboratory data revealed a normal blood count and serum chemistry. Her antinuclear antibodies, rheumatoid factor, SSA, and SSB were all negative.

A scalp biopsy revealed dense fibrosis consistent with scarring in the upper dermis (Fig. 2). The epidermis was unremarkable. The number of hair follicles was diminished. Several residual well-developed follicles showed perifollicular fibrosis. Fibrous tracts at sites of previous follicular structures were present. There was a perifollicular mixed cell infiltrate with abundant mast cells, but there was essentially no inflammation present in the follicular epithelium. A mild perivascular inflammatory infiltrate was present. In the interstitium, the infiltrate also contained many plump mast cells and occasional eosinophils. Giemsa staining (Fig. 3) and immunohistochemical staining for tryptase (Fig. 4) showed a diffuse infiltrate of mast cells in the dermis and was focally perifollicular. The deep portions of the biopsy were unremarkable. No mucinous material was identified within the dermis.

Based on the histological impression of a markedly elevated number of mast cells on scalp biopsy, we performed two separate N-methylhistamine urine levels, which were each elevated at 348 and 378 mcg/g of creatinine (normal range is 50–250 mcg/g of creatinine). The patient's alopecia was treated with topical and intralesional corticosteroids with little improvement, and she was then lost to follow up.
Discussion


Mast cells are found primarily in the skin and in the lining of the bronchopulmonary tree and gastrointestinal tract. The characteristic granules of these cells contain a variety of inflammatory mediators, which are normally released only after appropriate stimulation. About 10% of the protein in mast cell granules is composed of the potent proteolytic enzymes chymase and tryptase.2 Mast cells also contain other inflammatory mediators including PGD2 and histamine. These mediators are thought to play a role in allergic reactions, fibrosis, arthritis, angiogenesis, and wound healing.3–5 A majority of patients with urticaria pigmentosa have mast cell granulomas in their bone marrow biopsy, and 50% of these patients also have abnormal liver and/or spleen scans.6 Often, patients with indolent skin involvement of mastocytosis also have substantial extracutaneous mast cell infiltrates, and the site of production of these mast cells is within the bone marrow.7 These patients usually have elevated blood and urine N-methylhistamine and/or serum PGD2. Therefore, cutaneous mastocytosis should be thought of as part of a systemic disease process, which can have various manifestations in the skin.

Previous studies have shed some light on the causes of mast cell accumulation in skin. Normal epidermal keratinocytes produce mast cell growth factor, also known as stem cell factor and c-kit ligand, which binds to the c-kit receptor on mast cells and probably causes their proliferation and accumulation.8 The lesions of patients with urticaria pigmentosa appear to have abnormal epidermal oversecretion of c-kit ligand,9 which is also found in dermal fibroblasts as well as in dermal dendritic cells and endothelial cells. The role of the c-kit receptor pathway in mastocytosis is further supported by the finding of point mutations in the catalytic domain of c-kit in patients with mastocytosis and associated hematological disease.10 Loss of c-kit expression, seen in piebaldism, may result in decreased mast cells in the skin. Therefore, it has been suggested that mastocytosis in the skin represents migration and accumulation of mast cells from the blood stream rather than a neoplastic process.

The etiology of most types of cicatricial alopecias remains obscure. Loss of follicular stem cells in the bulge or aberrant sebaceous glands are thought to play a role in causing permanent alopecias.11–13 Probably, the destruction of the follicle is the end result for many different pathological processes. Mast cells have been implicated in controlling hair follicle cycling as well as scarring and tissue remodeling.14,15 Thus, it is conceivable that mast cell infiltration of the scalp could result in cicatricial alopecia.

Although two cases of alopecia in newborns with mastocytosis have been reported in the French literature, 16,17 to our knowledge, mastocytosis presenting as scarring alopecia in an adult has never been reported. Mast cells are commonly found in the fibrous sheath of the hair follicle, and increases in the number of these mast cells and their degranulation has been observed within fibrous tract remnants in biopsy specimens of alopecia areata.18 One previous study failed to demonstrate an abnormal mastocytosis in alopecia areata because of a large variance of the number of mast cells in control scalp biopsies; however, the same study demonstrated an increased number of mast cells in a mouse model for alopecia areata.19 Others have found that degranulating mast cells were commonly associated with lymphocytes near the bulge area, and numerous mast cells were associated with male pattern alopecia.20 However, no one has ever reported testing for the presence of systemic mastocytosis in a patient with cicatricial alopecia and an infiltrate rich in mast cells.

This case raises the possibility of an association between scarring alopecia and mast cell disease. Mast cells have been implicated in the regulation of both anagen onset14 and catagen onset in mice.21 Mast cell granules contain many growth factors and cytokines, such as fibroblast growth factors and vascular endothelial derived growth factors. Receptors for these mediators have been implicated in hair follicle development and cycling.22 Mast cells also contain heparin and other serpins capable of modulating the effects of growth factors. Several proinflammatory interleukins (tumor necrosis factor-alpha, interleukin-4, and interleukin-6) are also found in mast cell granules and these products have been implicated in collagen synthesis and cutaneous fibroplasias. Recently, Lee et al. showed that c-kit-mutant mice, which lack mast cells, display little clinical or histological evidence of arthritis compared with control littermate mice when exposed to arthritogenic serum.23 This suggests that mast cells are the downstream effectors causing joint destruction in autoimmune arthritis. Similar studies are necessary to determine if mast cells play a role in the pathobiology of cicatricial alopecias. A quantitation of mast cell numbers in cicatricial alopecias compared with normal scalp may yield further insights into the possible association of mast cells with scarring alopecias. Our report should prompt these investigations as well as a search for other patients with cicatricial alopecia and infiltrates rich in mast cells.

The scalp biopsy from this patient showed scarring alopecia with a markedly increased number of plump mast cells as well as mast cell degranulation. These findings prompted testing for systemic mastocytosis, which remarkably was discovered. Mastocytosis had not previously been suspected in this patient. Her medical history of frequent abdominal cramps, occasional episodic hot flashes, hyper-reactive skin reaction to insect bites, and her cardiac arrhythmia may have represented the systemic manifestations of mastocytosis. In summary, scarring alopecia with an increased number of mast cells on scalp biopsy warrants entertainment of the diagnosis of mastocytosis, which can be confirmed by testing the urine for elevated levels of histamine metabolites."

 

[bornthisway]

Inhibiting mast cell activation?

Mast cells as targets of corticotropin-releasing factor and related peptides.

Trends Pharmacol Sci. 2004 Nov;25(11):563-8

Theoharides TC, Donelan JM, Papadopoulou N, Cao J, Kempuraj D, Conti P.

Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA. theoharis.theoharides_AT_tufts.edu

Several inflammatory skin conditions, including atopic dermatitis (AD) and psoriasis, are exacerbated by stress. Recent evidence suggests that crosstalk between mast cells, neurons and keratinocytes might be involved in such exacerbation. Mast cells are distributed widely in the skin, are present in increased numbers in AD and are located in close proximity to substance P- or neurotensin-containing neurons. Corticotropin-releasing factor (CRF), its structurally related peptide urocortin (Ucn) and their receptors are also present in the skin and their levels are increased following stress. Human mast cells synthesize and secrete both CRF and Ucn in response to immunoglobulin E receptor (FcepsilonRI) crosslinking. Mast cells also express CRF receptors, activation of which leads to the selective release of cytokines and other pro-inflammatory mediators. Thus, we propose that CRF receptor antagonists could be used together with natural molecules, such as retinol and flavonoids, to inhibit mast cell activation and provide new therapeutic options for chronic inflammatory conditions exacerbated by stress.

PMID: 15491778

I have to prepare for some tests so I won't have much time this week to post.

Something I was considering after the recent finasteride hormonal study I posted ( Finasteride and IGF-I theory ) .. ROS drives expression of TGF-b1 in dermal papilla, by decreasing ROS we decrease that expression which is involved in miniaturization/hair growth retardation. At the same time, high ROS causes IGF-I receptor insensitivity, so by reducing (not eliminating) ROS we reactivate IGF-I receptor sensitivity.

A related study..

Role of reactive oxygen species (ROS) on androgen-inducible TGF-beta1 regulation of dermal papilla cells.

Hyeon Gyeong Yoo, Yong Jung Kang, Se Rah Lee, Hyun Keol Pyo, Oh Sang Kwon, Kyu Han Kim, Hee Chul Eun, Kwang Hyun Cho,

Department of Dermatology, Seoul National University, College of Medicine, Laboratory of Cutaneous Aging and Hair Research, Clinical Research Institute, Seoul National University Hospital and Institute of Dermatological Science, Seoul National University, Seoul, Korea

Little is known about the roles of androgen on the regulation of redox state in the dermal papilla cells, a cellular process known to profoundly increase with aging. The androgen receptor (AR) has been reported to modulate TGF-beta1/Smad signaling and to be overexpressed in androgen-dependent scalp area of the patients with androgenetic alopecia. The rat vibrissae dermal papilla cell line (DP-6) overexpressed with AR was investigated to evaluate the role of ROS on androgen-induced increase of TGF-beta1 secretion. The AR stably-transfected DP-6 cells were incubated with R1881 or dihydrotestosterone (DHT). Flow cytometry and laser scanning confocal microscopy were undergone to measure ROS production and ELISA assay to evaluate TGF-beta1 secretion after androgen treatment. TGF-beta1 promoter activity assay was also performed whether to be influenced by pretreatment of ROS scavengers. Androgen markedly increased ROS generation and the androgen-inducible ROS augmented TGF-beta1 secretion from dermal papilla cells. Treatment with ROS scavenger or several species of inhibitors decreased ROS production and TGF-beta1 expression. Luciferase reporter assays showed suppression of TGF-beta1 promoter signaling by ROS scavengers. In conclusion, our study shows for the first time that androgen-induced TGF-beta1 accumulation in dermal papilla cells would be mediated by ROS production and prevented by antioxidants or ROS inhibitors.

 

[harold]

OK here is the whole study. Quick comments: seems this is an undeniable and very consistent finding. The question is then is it a cause or a consequence? Is tgf-beta or what have you knocking off hair and then attracting mast cells to the vicinity or is it the mast cells themselves that are respon sible for the hair loss. ie Will inhibiting/eliminating the mast cells help. Some lines of evidence indicate that it may. The above study about a woman with what looks like female pattern hair loss apparently caused by mastocytosis. The powerful effect of mast cells on hair cycles as demonstrated by Paus et al and others over the years.

Dont know if this is the place to raise it but reading another new study today I found a mention of a commercial PGDS inhibitor - tranilast. Apparently found in some OTC nasal sprays and eye drops. The good news is that it appparently inhibits both the lipocalin and the hemot.... the other type of PGDsynthase. This is important because Cotsarelis was specific that it was the lipocalin type (which incidentally is NOT contained in mast cells) that is so upregulated by androgens in balding scalp.

"Biochem Pharmacol. 1989 Aug 15;38(16):2673-6.
Inhibitory effect of tranilast on prostaglandin D synthetase.
Ikai K, Ujihara M, Fujii K, Urade Y.

Department of Dermatology, Kyoto University Faculty of Medicine, Japan.

The effect of Tranilast [N-(3,4-dimethoxycinnamoyl) anthranilic acid] on the synthesis of prostaglandin D2 (PGD2) by homogenates of rat peritoneal mast cells was investigated. The major cyclooxygenase product formed by mast cell homogenates was PGD2, smaller quantities of PGE2 and PGF2 alpha were also formed. Tranilast suppressed the production of PGD2 in a dose-dependent manner with an IC50 of 0.1 mM. This suppression was due to inhibition of PGD synthetase, but not cyclooxygenase, since the formation of PGE2 and PGF2 alpha were unchanged at a 0.1 mM concentration. In addition, the glutathione-dependent conversion of [14C]PGH2 to PGD2 by PGD synthetase (PGH-D isomerase, EC 5.3.99.2) was inhibited by Tranilast, with 50% inhibition achieved at 0.08 mM in broken cell preparations of rat peritoneal mast cells. Tranilast also inhibited purified rat spleen and brain PGD synthetases. Furthermore, Tranilast prevented the PGD2 generation from intact mast cells stimulated by the calcium ionophore A23187. These results suggest that Tranilast exerts some of its therapeutic effects by prevention of PGD2 generation in mast cells and some other tissues."

Anyway here is the study.

Introduction

Male pattern hair loss (MPHL) is hereditary and androgen-dependent, and is characterized by the progressive thinning of scalp hair in a defined clinical pattern [8, 27]. Androgens and genetic susceptibility are well known to produce predictable patterns of hair loss [8, 27], and histological observations of balding scalp biopsies have revealed that the miniaturization of terminal hairs is a distinguishing feature of MPHL and that this is frequently associated with perifollicular fibrosis [16, 32]. Concerning fibrosis and its relationship to alopecia, connective sheath fibrosis may play a negative role in MPHL by physically blocking normal follicular cycling [34].

It has been suggested that an inflammatory process is, at least in part, responsible for MPHL [17, 19, 26]. In addition, the histological features of MPHL have been reported to show perifollicular micro-inflammation, fibrous streams, and diffuse mast cells (MC) infiltration with focal perifollicular localization, along with the miniaturization of hair follicles [19, 26, 27]. It has also been reported that an association exists between alopecia and mastocytosis [33]. Accordingly, the above findings suggest that MCs and MPHL are related.

This study was undertaken to investigate whether MC infiltration is involved in the development and progression of MPHL, and to clarify the possible relationship between MCs and dermal fibrosis in MPHL. Numbers of tryptase- and chymase-positive MCs were evaluated in MPHL, and the correlations between these protease-positive MCs and dermal accumulations of collagen and elastic fiber bundles were investigated.

Ten patients with MPHL, showing no more than 5-cm circles of hair loss on their vertices (Ludwig–Hamilton classification IIIv to IV only), and five normal subjects without any history of hair loss or a family history of MPHL participated in this study. All the subjects were male, ranging in age from 20 to 35 years. Subjects who had dermatological disorders of the scalp were excluded. The Institutional Review Board of Seoul National University Hospital approved the protocol for this study, and written informed consent was obtained from all subjects.

Two paired 4-mm punch biopsies were taken from the balding vertex and haired occipital promontory area of the scalp of each subject. The vertex biopsy specimen was taken from the balding transitional regions of diminished hair density in patients with MPHL and the central vertex area in normal subjects. Biopsied specimens were fixed in 10% formalin for 24 h before being processed into paraffin wax and then sectioned horizontally at the approximate level of the entry of the sebaceous ducts into the follicles, usually 1–1.5 mm below the dermoepidermal junction. Masson trichrome and Victoria blue staining were respectively performed on the mounted serial 4 ?m thick sections for observation of the collagen framework and elastic fiber structural pattern. For immunostaining, sections were deparaffinized with xyrene and rehydrated through graded alcohols to water and boiled with target retrieval solution (Dako, Glostrup, Denmark). Sections were incubated in 3% H2O2 in phosphate-buffered saline and blocking solution for 30 min, and the sections were then incubated with the primary antibodies at 4°C overnight. Antibodies used and dilutions were as follows: monoclonal anti-tryptase (Dako, Denmark, 1:4,000), or monoclonal anti-chymase antibody (Calbiochem, Germany, 1:4,000). After rinsing in phosphate-buffered saline, the sections were visualized using an LSAB kit (Dako, Glostrup, Denmark), and the color reaction was performed with diaminobenzidine as a chromogenic substrate. The sections were counterstained briefly in Mayer’s hematoxylin. Control staining was performed with normal mouse immunoglobulin and showed no immunoreactivity (data not shown). After washing in running tap water for 5 min, the samples were dehydrated and mounted using permount medium (SP15-500, Fisher Scientific, NJ, USA.).

Using an automated image analysis system (IMTechnology, Daejeon, Republic of Korea), the total dermal area was calculated, excluding the space occupied by hair follicles inside the vitreous membrane and sebaceous glands, and the partial area occupied with collagen bundles or elastic fibers, which were positively stained by Masson Trichrome or Victoria blue staining, was determined. To assess the degree of dermal fibrosis, the volume percentage of collagen or elastic fibers (%) in each section was then calculated as the mean ± SEM in three different fields.

Tryptase-positive or chymase-positive MCs were counted in six or more different horizontally-adjacent fields at 200× magnification on separate serial sections using a light microscope with a superimposed intersecting grid and expressed as MCs/mm2 section area. Cells displaying a strong cytoplasmic staining and a nucleus were counted. The percentages of collagen and elastic fibers and MC numbers in designated dermal fields were assessed by investigators blinded to the identity of the biopsy site or subject profile.

Statistical analyses were performed by using the Mann–Whiteney test, Wilcoxon signed rank test, and P-values of less than 0.05 were considered statistically significant. The relationship between the increment of the collagen bundle/elastic fiber and the number of tryptase-positive/chymase-positive cells was analyzed by Pearson’s correlation analysis. All analyses were performed using SPSS 11 Software (SPSS, Chicago, IL, USA).

Collagen bundle and elastic fiber increases in balding vertex with MPHL

The diameters of hair follicles from balding vertex area of MPHL patients were found to be significantly reduced by 29.4% compared with those from non-balding control vertex scalp. The mean diameter of hair follicles was 206.8 ± 32.8 (mean ± SEM) in balding vertex scalp and 292.7 ± 12.0 in non-balding control vertex scalp, respectively (arbitrary unit, P < 0.05, Mann–Whiteney test).
Quantifications of collagen bundles and elastic fibers are shown in Fig. 1. Between the non-balding scalp area of MPHL subjects (45.5 ± 2.3%, mean ± SEM) and that of normal controls (42.3 ± 3.7%), the volume percentages of collagen bundles showed no significant difference. A significantly increased percentage of collagen bundles were only found in the balding vertex area with MPHL compared to the non-balding occiput scalp (P < 0.05) (Fig. 1a), and some increase in the percentage of collagen bundles was found in the bald vertex area compared to the control subjects.

MediaObjects/403_2007_826_Fig1_HTML.gif
Fig. 1 Histochemical and immunohistochemical images in collagen bundles and elastic fiber frameworks. The figures shown are representative sections of vertex and occiput scalp skins of MPHL subjects and normal controls. Total dermal cross sectional areas were calculated (regions covered by hair follicles and sebaceous glands were excluded). Areas occupied by collagen bundles (a) or elastic fibers (b) were determined using an automated image analysis system. Values are means ± SEM. (Original magnification ×200, square insert ×400)

Interestingly, a significant increase of elastic fiber framework area of nearly 4-fold was also observed in both the vertex and occipital scalp with MPHL (P < 0.001) (Fig. 1b). The volume percentage of elastic fibers was higher in vertex scalp skin compared to occipital scalp in control and MPHL subjects, similar to the expression of collagen bundles. Only balding vertex scalp skin revealed significantly more elastic fibers in MPHL subjects than in controls (P < 0.01) (Fig. 1b).

Increases in elastic fibers were correlated with increased numbers of mast cells in balding vertex with MPHL
Tryptase-positive, total MC numbers (MCT and MCTC) of site-matched scalp samples were about twice as high in MPHL subjects. Moreover, even non-balding occiput scalp samples of MPHL subjects showed greater MC numbers than those of normal controls, and these numbers were similar to those of control vertex scalp skin. MC numbers tended to increase in the same manner (1.7-fold increase, respectively) in the vertex skins of MPHL subjects (P < 0.001) and controls (P < 0.05) (Fig. 2a). Numbers of chymase-positive MCs were also higher in MPHL subjects (by about 1.5-fold) than in controls in both the vertex and occiput skin.

MediaObjects/403_2007_826_Fig2_HTML.gif
Fig. 2 Quantification of mast cells in the balding and non-balding scalp skins of patients with MPHL and in controls. a Tryptase-positive (total MCs) and chymase-positive MCs were counted. Data are presented as means ± SEM. Statistical analysis was performed using Wilcoxon’s signed rank test (original magnification ×200, square boxes ×400). b Relationships between increases in the amount of elastic fibers and numbers of tryptase-positive and chymase-positive MCs. Both correlations were significant by Pearson’s correlation analysis

To determine whether MC numbers were correlated with increases in fibrotic materials, we investigated the relationships between tryptase or chymase-positive MCs and volume percentages of collagen and elastic fibers. Significant correlations were found between volume percentages (%) of elastic fibers and tryptase and chymase-positive MCs (r = 0.58, 0.60, respectively, Pearson’s correlation analysis) (Fig. 2b).

Although androgens are primarily responsible for MPHL [14, 15, 22], the implication of microscopic inflammation in the pathogenesis of MPHL was also suggested from several studies [17, 19, 26, 28]. Sueki, et al. analyzed MC infiltration quantitatively and the ultra-structures of alopecic scalp areas, and suggested that micro-inflammation probably accelerates MPHL by inducing aberrant fibrosis [26].

In the present study, the amount of collagen bundles and elastic fibers and the number of MCs were quantified using an image analysis system to determine the nature of the relationship between dermal matrix remodeling and MC infiltration in MPHL. Initially, we analyzed connective tissue patterns by comparing balding vertex and haired occipital areas, and found significantly more collagen bundles and especially of elastic fibers in balding vertex scalp skin than in non-balding occipital scalp skin. Moreover, MC numbers were found to be elevated not only in the perifollicular sheaths of MPHL lesions, as has been previously reported [26], but also in interfollicular dermis. Furthermore, a significant correlation was found between dermal MC densities and amounts of elastic fiber and collagen bundles in the balding vertex skin of MPHL patients.

Mast cells are well known to play a critical role in allergic diseases and to be implicated in inflammatory disorders [24]. In addition, mast cell accumulations are often observed in fibrotic disorders of the skin, e.g., keloid, systemic sclerosis, and during wound healing [9, 18, 21, 23, 30]. The effects of activated mast cells on dermal fibroblast proliferation and collagen and glycosaminoglycans synthesis have been well demonstrated [1, 2]. Moreover, it has also been suggested that mediators and enzymes of mast cells are key initiating agents of perifollicular micro-inflammation and perifollicular fibrosis [19, 26]. MCs may directly or indirectly synthesize and release several mediators capable of modulating extracellular matrix production and degradation [7, 12]. These mediators include TNF-alpha, transforming growth factor (TGF)-beta, prostaglandin (PG)-D2, and basic fibroblast growth factor (bFGF) [1, 7, 12, 13]. TGF-beta is considered a key element in the fibrotic process [3, 29]. Furthermore, tryptase is known to stimulate fibroblast proliferation, to induce mRNAs required for collagen production [5, 13, 25], to increase elastin production in fibroblasts in bladder walls [11]. Therefore, MC accumulations might be responsible for increased collagen and elastic fiber synthesis in MPHL.

Regarding MPHL, Yoo et al. [34], demonstrated that androgen directly stimulated procollagen synthesis in bald scalp skin, and increase in elastic fibers was observed with the progression of alopecia [4], thus some type of dermal matrix remodeling in alopecia lesions appears to contribute to the miniaturization of hair follicles, a well known feature of MPHL.

Perifollicular T cell infiltrations have a role in development of alopecia including scarring alopecia, alopecia areata, and alopecia mucinosa [6, 10, 31, 33]. The role of T cells has also been investigated in the fibrotic processes associated with scleroderma [20]. Thus, it appears that T cells are may be involved in MPHL. However, alike other types of alopecia, little evidence about the implication of T cells on MPHL was reported. Further studies will be required.

In the present study, we found increases in MC numbers and collagen bundle and elastic fiber volumes were more marked in the vertex scalp skins of MPHL patients. Thus, differences in mast cell infiltration and secondary connective tissue changes may play an additional role in the progression of MPHL caused largely by androgens. Our results encourage use to suggest that MCs elicit a fibro-proliferative response in MPHL. However, further studies are necessary to determine the functional significances of our findings.
Acknowledgment This study was supported by a grant from the Korea Health 21 R&D Project, Ministry of Health & Welfare, Republic of Korea (A030086), and by a research agreement with AmorePacific Corporation, Republic of Korea.

References
1. Abe M, Kurosawa M, Ishikawa O, Miyachi Y (2000) Effect of mast cell-derived mediators and mast cell-related neutral proteases on human dermal fibroblast proliferation and type I collagen production. J Allergy Clin Immunol 106:S78–S84
PubMed CrossRef ChemPort

2. Abe M, Yokoyama Y, Amano H, Matsushima Y, Kan C, Ishikawa O (2002) Effect of activated human mast cells and mast cell derived mediators on proliferation, type 1 collagen production and glycosaminoglycans synthesis by human dermal fibroblasts. Eur J Dermatol 12:340–346
PubMed ChemPort

3. Border WA, Noble NA (1994) Transforming growth factor beta in tissue fibrosis. N Engl J Med 331:1286–1292
PubMed CrossRef ChemPort

4. Elston DM, McCollough ML, Warschaw KE, Bergfeld WF (2000) Elastic tissue in scars and alopecia. J Cutan Pathol 27:147–152
PubMed CrossRef ChemPort

5. Fiorucci L, Ascoli F (2004) Mast cell tryptase, a still enigmatic enzyme. Cell Mol Life Sci 61:1278–1295
PubMed SpringerLink ChemPort

6. Gilhar A, Paus R, Kalish RS (2007) Lymphocytes, neuropeptides, and genes involved in alopecia areata. J Clin Invest 117:2019–2027
PubMed CrossRef ChemPort

7. Gonzalez S, Moran M, Kochevar IE (1999) Chronic photodamage in skin of mast cell-deficient mice. Photochem photobiol 70:248–253
PubMed ChemPort

8. Haber RS (2006) Pathogenesis and medical therapy of male and female pattern hair loss In: Haber RS, Stough DB (eds) Hair transplantation. Elselvier, Philadelphia, pp 1–7

9. Hawkins RA, Claman HN, Clark RA, Steigerwald JC (1985) Increased dermal mast cell population in progressive systemic sclerosis; a link in chronic fibrosis? Ann intern Med 102:182–186
PubMed ChemPort

10. Horenstein MG, Simon J. (2007) Investigation of the hair follicle inner root sheath in scarring and non-scarring alopecia. J Cutan Pathol 34:762–768
PubMed CrossRef

11. Howard PS (2001) Mast cell enzymes alter the connective tissue phenotype of bladder wall fibroblasts and smooth muscle cells. Urology 57(6 Suppl 1):112–113
PubMed CrossRef ChemPort

12. Huttunen M, Harvima IT (2005) Mast cell tryptase and chymase in chronic leg ulcers: chymase is potentially destructive to epithelium and is controlled by proteinase inhibitors. Br J Dermatol 152:1149–1160
PubMed CrossRef ChemPort

13. Inoue Y, King Telogen Effluvium Jr, Barker E, Daniloff E, Newman LS (2002) Basic fibroblast growth factor and its receptors in idiopathic pulmonary fibrosis and lymphangioleiomyomatosis. Am J Respir Crit Care Med 166:765–773
PubMed CrossRef

14. Inui S, Fukuzato Y, Nakajima T, Yoshikawa K, Itami S (2002) Androgen inducible TGF beta1 from balding dermal papilla cells inhibits epithelial cell growth: a clue to understand paradoxical effects of androgen on human hair growth. FASEB J 16:1967–1969
PubMed ChemPort

15. Itami S, Inui S (2005) Role of androgen in mesenchymal epithelial interactions in human hair follicle. J Investig Dermatol Symp Proc 10:209–211
PubMed CrossRef ChemPort

16. Jahoda CA (1998) Cellular and developmental aspects of androgenetic alopecia. Exp Dermatol 7:235–248
PubMed CrossRef ChemPort

17. Jaworsky C, Kligman AM, Murphy GF (1992) Characterization of inflammatory infiltrates in male pattern alopecia: implications for pathogenesis. Br J Dermatol 127:239–246
PubMed CrossRef ChemPort

18. Lee YS, Vijayasingam S (1995) Mast cells and myofibroblasta in kelod: a light microscopic, immunohistochemical and ultrastructural study. Ann Acad Med Singapore 24:902–905
PubMed ChemPort

19. Mahe YF, Michelet JF, Billoni N (2000) Androgenetic alopecia and microinflammation. Int J Dermatol 39:576–584
PubMed CrossRef ChemPort

20. McGaha TL, Bona CA (2002) Role of profibrogenic cytokines secreted by T cells in fibrotic processes in scleroderma. Autoimmun Rev 1:174–181
PubMed CrossRef ChemPort

21. Nishioka K, Kobayashi Y, Katayama I, Takijiri C (1987) Mast cell numbers in diffuse scleroderma. Arch Dermatol 123:205–208
PubMed CrossRef ChemPort

22. Obana N, Chang C (1997) inhibition of hair growth by testosterone in the presence of dermal papilla cells from the frontal bald scalp of the postpubertal stumptailed macaque. Endocrinology 138:356–361
PubMed CrossRef ChemPort

23. Rothe MJ, Nowak M, Kerdel FA (1990) The mast cells in health and disease. J Am Acad Dermatol 23:615–624
PubMed ChemPort

24. Ryan JJ, Kashyap M, Bailey D, Kennedy S, Speiran K, Brenzovich J, Barnstein B, Oskeritzian C, Gomez G (2007) Mast cell homeostasis: a fundamental aspect of allergic disease. Crit Rev Immunol 27:15–32
PubMed ChemPort

25. Saito H (2005) Role of mast cell proteases in tissue remodeling. Chem Immunol Allergy 87:80–84
PubMed ChemPort

26. Sueki H, Stoudemayer T, Kligman AM, Murphy GF (1999) Quantitative and ultrastructural analysis of inflammatory infiltrates in male pattern alopecia. Acta Derm Venereol 79:347–350
PubMed CrossRef ChemPort

27. Trüeb RM (2002) Molecular mechanisms of androgenetic alopecia. Exp Gerontol 37:981–990
PubMed CrossRef

28. Trüeb RM (2005) Aging of hair. J Cosmet Dermatol 4:60–72
PubMed CrossRef

29. Verrecchia F, Mauviel A, Farge D (2006) Transforming growth factor-beta signaling through the Smad proteins: role in systemic sclerosis. Autoimmun Rev 5:563–569
PubMed CrossRef ChemPort

30. Wang HW, Tedla N, Hunt JE, Wakefield D, McNeil HP (2005) Mast cell accumulation and cytokine expression in the tight skin mouse model of scleroderma. Exp Dermatol 14:295–302
PubMed CrossRef ChemPort

31. Wasy?yszyn T, Koz?owski W, Zabielski SL. (2007) Changes in distribution pattern of CD8 lymphocytes in the scalp in alopecia areata during treatment with diphencyprone. Arch Dermatol Res 299:231–237
PubMed SpringerLink

32. Whiting DA (1993) Diagnostic and predictive value of horizontal sections of scalp biopsy specimens in male pattern androgenetic alopecia. J Am Acad Dermatol 28:755–763
PubMed ChemPort

33. Xu X, Solky B, Elenitsas R, Cotsarelis G (2003) Scarring alopecia associated with mastocytosis. J Cutan Pathol 30:561–565
PubMed CrossRef ChemPort

34. Yoo HG, Kim JS, Lee SR, Pyo HK, Moon HI, Lee JH, Kwon OS, Chung JH, Kim KH, Eun HC, Cho KH (2006) Perifollicular fibrosis: pathogenetic role in androgenetic alopecia. Biol Pharm Bull 29:1246–1250
PubMed CrossRef ChemPort

 

[harold]

I know I have kind of poured water on the significance of tgf-beta in male pattern baldness before - but could it be behind the mast cell/inflammatory cascade? It would be a nice neat explanation and would fit in with the in vitro effects of androgens/tgf-beta upon dermal keratinocytes/hair follicles.
hh

Transforming growth factor-beta 1 mediates mast cell chemotaxis

BL Gruber, MJ Marchese and RR Kew
Department of Medicine, State University of New York, Stony Brook 11794.

It remains unknown which factor(s) control mast cell recruitment in chronic immune reactions. Although TGF-beta has been shown to function as a potent chemotactic factor for monocytes, fibroblasts, and neutrophils, its effect on mast cells has not been previously determined. In this study, TGF-beta 1 was shown to cause directed migration of cultured mouse mast cells at femtomolar concentrations, with a maximal chemotactic response observed at 25 fM. Moreover, chemotaxis to TGF-beta was also seen using freshly isolated rat peritoneal mast cells. Addition of neutralizing Ab to TGF-beta abrogated its chemotactic activity for both freshly isolated rat peritoneal mast cells and cultured mouse mast cells, whereas an irrelevant species-matched control Ab had no effect. Checkerboard analysis confirmed the mast cell chemotactic activity after exposure to concentration gradients of TGF-beta. Mast cells were observed to undergo rapid and extensive shape changes on exposure to TGF-beta, assuming a polarized morphology in preparation for migration. Other known mast cell chemoattractants including laminin, c-kit ligand, and IL-3 were found to be considerably less potent on a molar basis in inducing directed migration. Affinity cross-linking studies identified TGF-beta binding proteins with M(r) at 70 and 288 kDa, consistent with types I and III TGF-beta receptors on the mast cells. In summary, TGF- beta is the most potent chemoattractant described for mast cells and conceivably relevant, because pathologic processes mediated by TGF-beta are often associated with mast cell accumulation.