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.
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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.
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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.
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