Botulinum toxin blocks mast cells and prevents rosacea like inflammation

Background

Rosacea is a chronic inflammatory skin condition whose etiology has been linked to mast cells and the antimicrobial peptide cathelicidin LL-37. Individuals with refractory disease have demonstrated clinical benefit with periodic injections of onabotulinum toxin, but the mechanism of action is unknown.

Analysis of mast cell subpopulations (MCT, MCTC) in cutaneous inflammation using novel enzyme-histochemical staining techniques

Abstract In order to gain insights into the dynamics of mast cell subpopulations in normal and diseased skin, a novel enzyme-histochemical double and triple staining method was employed that allowed the detection of metachromasia (toluidine blue) and the mast cell proteases tryp-tase and chymase within the same cell. Cryostat sections were used of skin biopsies from the following specimens: normal skin (N=4), psoriasis (N=13), atopic eczema (N=7), lichen planus (N=6), interferon α2a injection sites (N=l) of a leukemic infiltrate and corresponding normal skin of the same patient before and after treatment. (i) Equal numbers of tryptase-and chymase-positive mast cells (MCTC) were obtained in all normal and diseased specimens in papillary and reticular dermis, with threefold increases around appendages, (ii) Tryptase-positive mast cells (MCT) were absent in normal skin, but were markedly increased in a disease-specific pattern within the papillary dermis, the inflammatory infiltrate and around appendages, (iii) Marked increases of MCT were also noted at interferon injection sites within the leukemic infiltrate, but not in the normal skin of the same patient. These data suggest that disease-dependent mast cell dynamics involve only MCT in cutaneous inflammation and that MCT numbers are controlled by distinct, disease-specific local tissue factors.     

Polymorphism of the mast cell chymase gene (CMA1) promoter region: lack of association with asthma but association with serum total immunoglobulin E levels in adult atopic dermatitis

BACKGROUND: Mast cell chymase has the potential to be an important mediator of inflammation and remodelling in the asthmatic lung. Previous studies have examined association between promoter polymorphism of the chymase gene (CMA1) and allergic phenotypes but the significance of this polymorphism is unclear. We have examined association of a CMA1 variant in relation to asthma in a large UK Caucasian family cohort. METHODS: A polymorphism of the CMA1 gene promoter (-1903G/A) was genotyped in 341 asthmatic families and in 184 non-asthmatic adults recruited from the UK PCR-RFLP based genotyping. Association with asthma diagnosis, atopy, specific and total IgE, and atopy and asthma severity was examined. RESULTS: Case-control studies did not reveal a significant difference in allele frequency between asthmatics and controls. A significant association was found between CMA1 genotypes and total IgE levels in subjects with self-reported eczema that remained significant after correction for multiple testing (median total serum IgE GG 297 kU/L, GA 144 kU/L, AA 48.4 kU/L, Pc=0.0032). CONCLUSION: These data suggest that CMA1 promoter polymorphism does not contribute to asthma susceptibility or severity but may be involved in regulating IgE levels in patients with eczema.     

Mast cell tryptase may modulate endothelial cell phenotype in healing myocardial infarcts

Mast cells and macrophages infiltrate healing myocardial infarcts and may play an important role in regulating fibrous tissue deposition and extracellular matrix remodelling. This study examined the time-course of macrophage and mast cell accumulation in healing infarcts and studied the histological characteristics and protease expression profile of mast cells in a canine model of experimental infarction. Although macrophages were more numerous than mast cells in infarct granulation tissue, macrophage density decreased during maturation of the scar, whereas mast cell numbers remained persistently elevated. During the inflammatory phase of infarction, newly recruited leucocytes infiltrated the injured myocardium and appeared to be clustered in close proximity to degranulating cardiac mast cells. During the proliferative phase of healing, mast cells had decreased granular content and were localized close to infarct neovessels. In contrast, macrophages showed no selective localization. Mast cells in healing canine infarcts were alcian blue/safranin-positive cells that expressed both tryptase and chymase. In order to explain the pro-inflammatory and angiogenic actions of tryptase--the major secretory protein of mast cells--its effects on endothelial chemokine expression were examined. Chemokines are chemotactic cytokines that play an important role in leucocyte trafficking and angiogenesis and are highly induced in infarcts. Tryptase, a proteinase-activated receptor (PAR)-2 agonist, induced endothelial expression of the angiogenic chemokines CCL2/MCP-1 and CXCL8/IL-8, but not the angiostatic chemokine CXCL10/IP-10. Endothelial PAR-2 stimulation with the agonist peptide SLIGKV induced a similar chemokine expression profile. Mast cell tryptase may exert its angiogenic effects in part through selective stimulation of angiogenic chemokines.     

Role of chymase on growth of cultured canine Tenon's capsule fibroblasts and scarring in a canine conjunctival flap model

Chymase is a chymotrypsin-like serine protease contained in the secretory granules of mast cells. Recently, we reported that chymase activity and the number of chymase-positive mast cells in conjunctival tissues were significantly increased during the wound healing process in a hamster model of glaucoma surgery. However, it has been unclear the role of chymase on conjunctival scarring. In the present study, we evaluated the effect of dog chymase on cell proliferation of fibroblasts established from canine Tenon's capsule and the effect of a chymase inhibitor on scarring in a canine conjunctival flap model. After a fibroblast cell culture was established from canine Tenon's capsules, the fibroblasts were incubated in the presence of dog chymase (5-20 ng ml(-1)). Cell proliferation was evaluated by bromodeoxyuridine incorporation. In a canine conjunctival flap model, a sponge treated with a chymase inhibitor, Suc-Val-Pro-Phe(P)(OPh)(2), or placebo was placed in between the conjunctiva and sclera and the conjunctival incision was closed. One week after the surgery, adhesion degree was assessed, and chymase activities in the conjunctival lesion and in the areas of the conjunctiva and sclera were measured. In cultured canine Tenon's capsule fibroblasts, dog chymase significantly increased cell proliferation, and this chymase-dependent proliferation was completely suppressed by the chymase inhibitor. In the canine surgical model, chymase activity in placebo-treated eyes was significantly increased compared to control eyes, while it was significantly decreased by treatment with the chymase inhibitor. Scores for adhesion degree in the chymase inhibitor-treated eyes were significantly decreased in comparison with those in placebo-treated eyes. The conjunctival area in the chymase inhibitor-treated eyes was also suppressed to 52.6% compared with that in placebo-treated treated eyes. In conclusion, chymase stimulates proliferation of fibroblasts derived from canine Tenon's capsule and chymase may play an important role in scarring after glaucoma surgery.     

肥大细胞糜蛋白酶在瘢痕疙瘩组织的活性表达

目的探讨肥大细胞糜蛋白酶在人瘢痕疙瘩组织中的表达活性。方法采用免疫组织化学法检测瘢痕疙瘩组织和正常皮肤中肥大细胞的数量和糜蛋白酶的表达,并以RT-PCR和放免法检测瘢痕疙瘩和正常皮肤组织中糜蛋白酶mRNA表达活性变化。结果瘢痕疙瘩组织中肥大细胞数量与糜蛋白酶阳性表达评分为(10±0.25)个/HP、(6.2±0.23)mm2,明显高于正常皮肤组织的(4±0.22)个/HP、(2.5±0.12)mm2(P<0.01);RT-PCR结果显示瘢痕疙瘩组织中肥大细胞mRNA和糜蛋白酶mRNA表达水平较正常皮肤组织明显增高。结论肥大细胞糜蛋白酶存在于瘢痕疙瘩中且活性表达明显高于正常皮肤组织。     

固本防喘胶囊对慢性阻塞性肺疾病急性加重期患者治疗作用的研究

目的:探讨固本防喘胶囊对慢性阻塞性肺疾病(COPD)患者治疗作用的机制。方法:采用双盲随机方法将86例老年COPD急性加重期患者分为治疗组和对照组(各43例),两组基础治疗相同;治疗组加服中药固本防喘胶囊。采用酶联免疫吸附法(ELISA)检测痰中白细胞介素8(IL8)和嗜酸粒细胞趋化因子水平;采用酶标仪检测痰中类糜蛋白酶活性;比较治疗前后上述指标的变化。结果:1治疗组治疗后重、中度患者痰中类糜蛋白酶活性被抑制、IL8和嗜酸粒细胞趋化因子水平均显著降低,痰中中性粒细胞(NEU)和EOS计数亦降低;与治疗前比较差异均有显著性(P均<0.05),与对照组比较差异亦均有显著性(P均<0.05)。2痰类糜蛋白酶活性与IL8、嗜酸粒细胞趋化因子水平和临床症状评分均呈正相关(P均<0.01);IL8水平与痰NEU、EOS计数也均呈正相关(P均<0.05)。结论:固本防喘胶囊对COPD患者嗜酸粒细胞趋化因子、肥大细胞的抑制作用,可能是该方治疗COPD的机制之一。     

Significance of chymase-dependent angiotensin II formation in the progression of human liver fibrosis

Aim: Angiotensin II may contribute to liver fibrogenesis. In addition to angiotensin-converting enzyme (ACE), chymase, which is expressed by mast cells, is also known to be an angiotensin II-forming enzyme. However, it is unclear which of these two angiotensin II-forming enzymes plays a more important role in liver cirrhosis progression. In the present study, the role of angiotensin II-forming enzymes in the progression of liver cirrhosis was clarified. Methods: A total of 77 patients (16 in F0 stage, 10 in F1 stage, 22 in F2 stage, 12 in F3 stage, and 17 in F4 stage) were classified according to the new Inuyama classification into a non-cirrhosis (F0) group, an early cirrhosis (F1 + F2) group, and a chronic cirrhosis (F3 + F4) group. Results: Both chymase and total angiotensin II-forming activities were significantly higher in chronic cirrhosis patients than in the other two groups. However, there was nodifference among the three groups in ACE activity. On immunohistology, the number of chymase- and angiotensin II-positive cells was significantly higher in the chronic cirrhosis group than in the non-cirrhosis and early cirrhosis groups. There were significant correlations between the number of chymase-positive cells and the number of angiotensin II-positive cells, between the number of chymase-positive cells and the degree of fibrosis, and between the number of angiotensin II-positive cells and the degree of fibrosis. Conclusion: These results suggest that chymase-dependent angiotensin II formation may play an important role in hepatic fibrosis of patients with cirrhosis.     

Positive correlation between blood pressure or heart rate and chymase-dependent angiotensin II-forming activity in circulating mononuclear leukocytes measured by new ELISA

The aim of the present study was to establish a convenient clinically applicable assay method for chymase-dependent angiotensin II forming activity of circulating mononuclear leukocytes (CML), which was potentially a marker of tissue chymase activity. Using this method, association between CML chymase activity and clinical parameters was determined.

Cardiovascular outpatients (n = 170) without taking antihypertensive medication were recruited.

An ELISA for chymase-dependent angiotensin II-forming activity in CML was established using Nma /Dnp-modified angiotensin I.

Logistic regression analysis revealed that age and male gender were significant independent determinants of the increased CML chymase activity. After adjustment by age and gender, the CML chymase activity was positively correlated with systolic blood pressure, pulse rate, and the brain natriuretic peptide level.

The relation between blood pressure and CML chymase activity suggests that it might reflect that increased tissue chymase activity contributes to systemic high blood pressure and heart rate because plasma chymase is inactive due to inhibitory plasma inhibitors.