The density of myocardial and pericardial rat mast cells in isoproterenol-induced heart failure

Myocardial mast cells (MC) respond to cardiovascular pathology. The behavior of MC population in myocardium and pericardium of rats has been studied 24 h, 14, 28 and 60 days after two isoproterenol injections (at 24 h intervals). The extent of heart failure has been estimated by supersonic inspection 28 and 60 days after isoproterenol injections. The density of MCs of different degrees of maturity was estimated on paraffin sections stained with Alcian blue--Safranin. The MC density in myocardium of intact and experimental rats was relatively low: from 4 to 6 cells/mm2. The MC density in pericardium of intact rats was several times higher than in myocardium: 48.6 +/- 13.0 cells/mm2. In 24 h and 14 days after isoproterenol injections the pericardial MC density was 1.5 times higher than in control rats (P < 0.05) at the expense of increase in the number of mature MCs with Safranine-positive granules without the increase in the number of immature cells with Alcian blue-positive granules. In 28 days the pericardial MC density was 2 times higher than in intact rats (P < 0.05) at the expense of increase in number of immature and mature cells. In 60 days after isoproterenol injections the pericardial MC density and the ratio of immature and mature cells compared with control did not reach statistical significance. The changes in pericardial MC population corresponded to severity of heart failure according to functional indices. The findings show active reaction of pericardial MCs on myocardium dysfunction that stimulates the maturation of resident immature MCs in pericardium and migration of immature cells to pericardium of damage heart.     

A sharp increase in the density of pulmonary and pericardial mast cells under monocrotaline-induced pulmonary hypertension in rats

Multifunctional granular mast cells (MCs) are involved in various pathological processes. The response of MC populations of myocardium, pericardium and lung to pulmonary hypertension (PH) has been studies 8 weeks after injection of monocrotaline. Five intact and five experimental rats were used. The density of MCs of different maturity was estimated on paraffin sections stained with Alcian blue and Safranin. Expressiveness of PH was estimated by functional parameters with the help of echocardiograms and by morphological markers. The MC density in myocardium of the intact and experimental rats was relatively low: 2 to 4 cells/mm2. MC density in the pericardium of intact rats was 14 times higher than in myocardium and increased 3 times for PH. The mature Safranin-positive cells predominated (70-80%) in myocardium and pericardium of intact and experimental rats. The MC density in the lungs of intact rats was about 30 cells/mm2; 98% of these cells were immature Alcian-positive cells. The mean density of MCs in the lungs of rats with PH increased 5.6 times. The mature Safranin-positive cells appeared in the lungs of rats with severe pathology. The greatest number of MCs in lungs was in the rats with the most pronounced disorders of myocardium function and marked histological damages (injuries) of myocardium and lungs. The finding show active response of MC population to monocrotaline-induced PH that stimulates migration of immature MCs into pericardium and lungs from the outside. Our data indicate the important role of MCs in the pathogenesis of PH.     

Sharp increase in density of pulmonary and pericardial mast cells in monocrotaline-induced pulmonary hypertension in rats

Multifunctional granular mast cells (MCs) are involved in various pathological processes. The response of the MC population in the myocardium, pericardium, and lungs to pulmonary hypertension (PH) has been studied 8 weeks after the injection of monocrotaline. Five intact and five experimental rats were used. The density of MCs of different degrees of maturity was estimated in paraffin sections stained with Alcian blue and Safranin. The expression of PH was estimated by functional parameters using an echocardiogram and morphological markers. The MC density in the myocardium of intact and experimental rats was relatively low, i.e., 2–4 cells/mm². In the pericardia of intact rats, the MC density was 14 times higher than in the myocardia and increased by a factor of three in PH. In the myocardia and pericardia of intact and experimental rats, mature, Safranin-positive cells predominated (70–80%). In the lungs of intact rats, the MC density was about 30 cells/mm² and 98% of the cells were immature Alcian-positive cells. In lungs of rats with PH the mean density of MCs increased 5.6 times. In lungs of rats with severe pathologies, mature Safranin-positive cells appeared. The highest number of MCs in lungs was found in rats with distinctly pronounced disorders of myocardial function and marked histolological damages of myocardium and lung. The findings show the active reaction of the MC population to monocrotaline-induced PH, which stimulates the migration of immature MCs to the pericardium and lungs from the outside. The connection of cellular mechanisms of the development of PH with the function of MCs is not yet clear; however, the results of the present work indicate the important role of MCs in the pathogenesis of PH.     

The density of myocardial and pericardial rat mast cells in isoproterenol-induced heart failure

The multifunctional mast cells (MC), located in the myocardium, actively react to the pathology of a cardiovascular system. We investigated MC density in the pericardium and myocardium of rats in intact and experimental heart failure (HF) 24 h and 14, 28, and 60 days after two (at 24 h intervals) injections of Isoproterenol (IP) inducing necrosises in the myocardium. An expressiveness of HF was estimated with the help of ultrasonic scanning of the heart after 28 and 60 days after two IP injections. MC of different degrees of maturity were identified cytochemically on paraffin sections stained with Alcian blue-Safranine. The MC density in the myocardium of intact and experimental rats was relatively low, ranging from 4 to 6 cells/mm², thus the ratio of cells of a different degrees of maturity during HF development was reliably unchanging. In the fibrous layer of pericardium, the MC density was higher than in the myocardium and, for the intact rats, it amounted 48.6 ± 13.0 cells/mm². 24 h to 14 days after IP injections, the MC density in pericardium in contrast to intact sample increased on the average in 1.5 times (P < 0.05) at the expense of increase of density of more differentiated cells stained with Safranine, without density change of less differentiated cells stained with Alcian blue. After 28 days, the MC density in pericardium was 2 times higher than in the intact sample (P < 0.01) and, at the same time, the density of cells of a different maturity degree (P < 0.05) was considerably increased. For 60 days, the MC density and the balance of Alcian-and Safranine-positive cells did not differ reliably from the intact sample. The dynamic of behavior of the MC population of pericardium was corresponding to HF injury on functional parameters. The data obtained indicate the active reaction of MC pericardium on a dysfunction of the myocardium; it stimulates the maturation of resident MCs and the reinforcement of the population at the expense of the migration of cells from the outside, which allows us to propose an intensification of the MC secretory function.     

Effects of renin-angiotensin system inhibitors on density of rat myocardial, pericardial, and pulmonary mast cells in experimental heart failure

The activation of the renin-angiotensin system (RAS) plays a critical role in the pathogenesis of cardiac failures (CFs). Using a model of experimental CFs, we studied the effects of lisinopril (LP) and fosinopril (FP) (inhibitors of the angiotensin-converting enzyme), as well as of losartan (LT, antagonist of angiotensin II receptors), on the density of multifunctional mast cells (MCs). RAS inhibitors were injected for 4 weeks beginning 4 weeks after two (with 24-h intervals) isoproterenol injections. MCs of different degrees of maturity were identified in paraffin sections stained with Alcian blue and Safranin. The CF severity was estimated based on functional echocardiogram parameters and on morphological criteria in histological sections. The MC density in the myocardiums of intact rats, as well as of rats with CFs that were and were not treated with drugs was relatively low, i.e., 3–4 cells/mm². The MC density in pericardiums of intact rats was several times higher than in myocardiums, i.e., 35±7 cells/mm². In CFs, the density of pericardial MCs was 1.7 higher than in intact rats due to an increase in the density of immature cells stained with Alcian blue (p< 0.05). Injections of LP increased the MC density 1.4-fold due to the density of mature cells stained with Safranin (p< 0.01). Injections of FP and LT did not affect the MC density and the balance of cells of different degrees of maturity in the pericardium. In lungs, 96–99% of MCs were Alcian positive. In intact rats, rats with CF, and rats with CF treated with FP, the density of these cells was 30 cells/mm². Injections of LP and LT decreased the density of pulmonary MCs to 7 cells/mm² (p< 0.01) and 19 cells/mm² (p< 0.05), respectively. The functional parameters of the heart were consistent with the data of the morphological analysis. The improvement of myocardial function was only noted in rats with CF treated with FP and LT. The obtained data show that, in the myocardiums, pericardiums, and lungs of rats with CF, reaction of MCs (as the cell elements of the RAS tissue) to injections of inhibitors of RAS was diverse. In the pericardium, injections of LP stimulated the maturation of resident MCs, as well as the replenishment of the population at the expense of immature cells that migrate from outside (by means of the migration of immature cells from the outside). This allows us to suggest us that the secretory activity of these cells is intensified. Conversely, in lungs, injections of LP, like of LT, suppress the MC population.     

Myometrial cells induce angiogenesis and salvage damaged myocardium

Characteristically, uterine myometrial cells (MCs) are proliferative, inducing angiogenesis within the female reproductive organ. We evaluated whether MCs implanted into myocardium could also induce angiogenesis and restore heart function after injury. MCs were isolated from the adult rat uterus and cultured for three studies: 1) Intracellular VEGF levels were measured in MCs cultured with progesterone (10(-11), 10(-9), and 10(-7) M) (n = 6 tests per group). 2) Blood vessel density was evaluated 8 days after MCs (3 x 10(6) or 6 x 10(6)), smooth muscle cells (SMCs), or endothelial cells (n = 6 rats per group) were injected with matrigel into the subcutaneous tissue of adult rats. 3) MCs, SMCs (5 x 10(6)/rat), or media were injected into a transmural scar 3 wk after cryoinjury in rat hearts (n = 12 rats per group), and heart function, blood vessel density, and myocardial scar size and thickness were evaluated 5 wk later. In study 1, cultured MCs expressed VEGF, with levels significantly (P < 0.05) upregulated by progesterone at an optimal dose of 10(-11) M. In study 2, MCs injected into the subcutaneous tissue with matrigel induced significantly more blood vessels, especially large-diameter vessels, than did SMCs or endothelial cells (P < 0.01 for all groups). This angiogenic effect was greatest (P < 0.01) at higher doses of MCs and was enhanced by progesterone (10(-11) M). In study 3, MCs implanted into the injured myocardium increased blood vessel density at the implant area, reduced scar size, and improved cardiac function relative to SMCs and media. Overall, MCs induced angiogenesis in vitro and in vivo, prevented cardiac remodeling, and improved heart functional recovery after cardiac injury.     

Mast cell density: a quantitative index of acute liver inflammation

OBJECTIVE: To evaluate mast cell (MC) density, in liver tissues taken from young and aging rats treated with carbon tetrachloride (CCl4) or untreated, as a quantitative marker of acute liver inflammation and to investigate whether the density of MCs varied with the rats' age. STUDY DESIGN: Rats aged 2, 6, 12 and 19 months treated intraperitoneally with CCl4 were killed 2 and 24 hours after intoxication. Hepatocellular damage was established by measuring alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity. Four histologic sections of 12 specimens from each age group were stained with toluidine blue to identify the MCs, which were counted using a computer-assisted image analysis system. RESULTS: Histology showed hepatocellular necrosis with inflammatory infiltration both 2 and 24 hours after intoxication. Serum AST levels were high in the 6- and 12-month-old rats, whereas ALT levels were high in the those aged 2 and 19 months. Two and 24 hours after intoxication, MC density increased considerably in young rats but less so in rats aged 19 months. CONCLUSION: MC density can be a useful marker of acute liver inflammation. The greater density in young rats suggests that older rats have a reduced immune response or recruit fewer MCs.     

Effects of interleukin 3, interleukin 4, and fibroblasts on cultures of human lung mast cells in bronchoalveolar lavage fluids

The effects of T cell factors, including interleukin (IL)-3 and IL-4, and fibroblasts on the growth and differentiation of human lung mast cells (MCs) obtained by bronchoalveolar lavage (BAL) were examined. The number of MCs identified by alcian blue-safranin staining was twice that of the control culture without conditioned medium (CM) when BAL cells were cultured for 2 weeks in RPMI 1640 containing 10% fetal calf serum and partially purified CM derived from PHA-stimulated lymphocytes. In the presence of both recombinant (r) IL-3 and rIL-4, the number of MCs was twice as high as the control without increase in the per-cell histamine content after 2 weeks' culture. In umbilical cord blood cultures, IL-3 plus IL-4 augmented basophilic cells about 20-fold more than the control when cultured for 2 weeks. In some cases, the percentage of safranin-positive MCs was about 2-5 fold greater, with 2-7 fold higher histamine content, when cultured for 10 days with CM and fibroblasts derived from human embryonic lung. However, in all BAL experiments, there was no increase in the total number of MCs after culture compared with the initial number of MCs, unlike the umbilical cord blood cultures. These results suggest that T cell factors, including IL-3 and IL-4, and fibroblasts may influence the phenotype and the survival of lung mast cells in BAL, whereas there was no evidence for the presence of MC precursors in BAL fluids.     

Comparative cytophotometric analysis of the nucleic acid content in the cardiomyocytes of normal rats and following experimental infarct

The cytophotometrical investigation of gallocyanine-chrome alum stained cardiac muscle cells allows to ascertain that a mean content of the nucleic acids calculated for a single nucleus is essentially higher in the left ventricle myocytes in comparison with the left auricle cells of healthy adult rats. These values in 1-, 2- and 3-nuclear cells of the ventricle are, respectively, 21.3, 19.3, and 18.0, and 14.1, 13.7, 13.5 of arbitrary units (a. u.) in the auricle cells. A difference in cytoplasmic RNA contents of the same cells is more significant, these values are 65.7, 116.4, and 158.9 a. u. in ventricle myocytes, and 33.4, 60.8 and 95.2 a. u. in auricle cells. The nucleic acids content in the nuclei and RNA content in the cytoplasm increase with the development of proliferation in myocytes after experimental myocardial infarction. A relative increase in the nucleic acids content in the nuclei of the same cell types reaches 50, 24, and 10% 11 days after infarction and 56, 38, and 45% 31 days after infarction. A relative increase in cytoplasmic RNA of the same cells reaches, respectively, 52, 17, and 25%, and 70, 57, and 53% 11 and 31 days after infarction. These findings evidence on the greatest synthetic activity of the single-nuclear auricle muscle cells in the process of heart restoration after infarction.     

Thyroxine-induced cardiomegaly in rats of different age

In the present study the effect of thyroxine treatment on the development of cardiomegaly was compared in young (10-day-old) and adult (12-week-old) rats. L-thyroxine was administered subcutaneously in a dose of 1 mg per kg b.w. for 5 days. In young thyroxine-treated rats the heart weight increased by 79% in comparison with the control rats. The number of blood capillaries and muscle fibres per mm2 remained unchanged. The concentration of hydroxyproline was even lower than in control animals. The number of 3H-thymidine-labelled muscle cell nuclei was significantly higher both in the left and right ventricles of thyroxine treated rats. The density of capillaries and muscle fibres was significantly lower in adult rats than in the group of young animals. In adult thyroxine-treated animals the heart weight was higher by 36%, the number of capillaries and muscle fibres as well as the concentration of hydroxyproline was unchanged. Thyroxine induced significant increase in the number of DNA synthesizing nuclei of muscle cells in the left ventricle while the change in the right ventricular myocardium was not statistically significant. The present data indicate that a hyperplastic response of cardiac muscle cells to thyroxine occurs in both ventricles of young rats and also in the left ventricle of adult animals.     

Mast-cell secretion and angiogenesis, a quantitative study in rats and mice

The activation of the autogenous mast cells (MCs) in situ in intact mesenterial windows was elicited by the intraperitoneal injection of the MC secretagogue Compound 48/80 over a period of 1, 3 and 5 days in Sprague-Dawley rats and in C57 BL/6 and CBA/Ca mice. As a probe of MC secretion, the release of histamine was quantified fluorometrically at predetermined intervals during the treatment. Fourteen days after the start of the treatment, the angiogenic response was quantified histologically as the number of vessel profiles per unit length of mesenteric window. Both the MC-activating and the angiogenic effect of the 48/80-treatment was greater in the rats than in the mice. The occurrence of MC-mediated angiogenesis in the mouse is demonstrated here for the first time. In the rat, 48/80-induced MC mediated angiogenesis increased in a distinctly dose-dependent manner. Two daily doses of 48/80 was the most efficient angiogenic protocol tested; a single day's treatment increased the number of vessels almost fivefold. The remarkable potency of the angiogenic reaction following MC secretion supports our previous notion that MC-mediated angiogenesis may have therapeutic implications in poorly vascularized tissues.     

Rabies virus production in high vero cell density cultures on macroporous microcarriers

The purpose of the study was to investigate the rabies virus multiplication in Vero cell cultures performed on porous microcarriers, MCs (cellulose-Cytopore and gelatin-Cultispher G), which provide higher available surface area compared with solid (nonporous) MCs (DEAE-Cytodex 1). In a set of experiments performed at the same MC concentration (MCs per milliliter), cell densities regularly obtained in porous MC cultures were comparable, but almost twice as high as those in solid MC cultures. In addition, 41.1 +/- 3.9-, 35.2 +/- 2-, and 19.6 +/- 5.8-fold increases in cell concentration, relative to the initial cell number, along with maximum rabies virus titers of 6.3 +/- 0.3 x 10(4), 5 +/- 0.1 x 10(4), and 4.3 +/- 0.2 x 10(4) FFD(50)/mL were observed in Cytopore, Cultispher G, and Cytodex 1 MC cultures, respectively. When higher concentrations of MCs were employed, lower performances of virus production and MC-cell occupation (cells per MC or cells per square millimeter) were observed. Cell attachment to MCs was shown to be faster for Cytopore MCs and Cytodex 1 MCs than for Cultispher G MCs. Concerning the kinetics of cell multiplication on MCs, exponential cell growth, at similar specific cell growth rates, took place on Cytopore, Cultispher G, and Cytodex 1 MCs. In addition, cell densities as high as 2.1 +/- 0.2 x 10(6) cells/mL on Cytopore MCs, 1.8 +/- 0.1 x 10(6) cells/mL on Cultispher G MCs, and 1 +/- 0.3 x 10(6) cells/mL on Cytodex 1 MCs were regularly obtained in batch cultures. Optical as well as scanning and transmission electron microscopy studies carried out to analyze MC structure, MC cell occupation, and cell permissivity to virus infection demonstrated that there was uniform cell distribution in the external and internal areas of the MCs, suggesting an efficiency of virus synthesis. Our results indicate the usefulness of these supports for rabies virus antigen production, as well as possibilities for further optimization.     

食管癌细胞诱导肥大细胞迁移的小鼠模型

目的建立小鼠肥大细胞（mast cell,MC）迁移模型,探讨化疗药物三氧化二砷对人食管癌EC109细胞株生长的杀伤机理。方法利用肥大细胞的特征性蛋白酶抗体及其免疫荧光标记MC和PI标记EC109细胞内DNA;以流式细胞术分析小鼠腹腔液中肥大细胞各亚型的百分率及肿瘤细胞周期变化;使用激光扫描共聚焦显微镜显示肥大细胞内分泌颗粒的分布。并通过组织化学方法,观察各种诱导处理后小鼠肠组织肥大细胞由肠道向腹腔移动的变化。结果①根据流式细胞仪点图分布分析,将小鼠肥大细胞分为：类胰蛋白酶阳性、类糜蛋白酶阴性（MC T）;类糜蛋白酶阳性、类胰蛋白酶阴性（MC C）和类胰蛋白酶阳性、类糜蛋白酶阳性（MC TC）三种亚型,且T型MC明显多余TC型和C型（P〈0.05）;以共聚焦显微镜显示三种亚型的MC均含有丰富的分泌颗粒并分布于细胞膜内侧,为其出芽突起形成储备的状态。②经组织切片观察到诱导处理后小鼠肠组织MC由肠道向腹腔移动,且胰酶对MC的诱导作用大于食管癌细胞和As2O3。③经诱导迁移入腹腔的MC可能与癌细胞周期由S期向G2/M期跨越相关;As2O3能延迟食管癌细胞的G0/G1期,阻碍细胞向S期跨越,从而抑制食管癌细胞的生长。结论食管癌细胞移入小鼠腹腔,主要诱导T型MC参与免疫反应。在生物机体内环境（这里指MC影响）的条件下,As2O3对肿瘤细胞生长的作用主要表现为促使癌细胞周期的G0/G1期向S期跨越延迟,或G2/M期进入细胞分裂的延迟。     

Thymus mast cell numbers following perinatal and adult exposures to low intensity 0.5 Hz magnetic fields

In a factorial design, 40 male 200-day-old rats that had been exposed from 2.5 days before to 2.5 days after birth to either 0.5 Hz rotating magnetic fields (RMFs) between 10^–3T to 10^–6T or to sham fields and maintained after weaning in one of two typical caging conditions were exposed as adults to either one of three 0.5 Hz RMF intensities (10^–6T, 10^–7T or 10^–8T) or to sham fields or to colony room control conditions. The numbers of mast cells (MCs/mm²) were determined for thymus tissues stained with thionin and toluidine blue. Thymuses from adult rats that had been perinatally exposed to the RMF displayed a marginally significant 20% to 35% elevation in MC numbers relative to sham-field controls. However the adult exposures did not sïgnificantlÿ affect the MC numbers. The two postweaning caging conditions, a non-magnetic field comparator variable, induced a significant 35% difference in MC numbers. The absence of sïgnificant perinatal by adult RMF exposure interactions indicated that early magnetic field exposure did not alter adult thymus responsivity to weaker but more natural intensity levels.     

The development of activity of succinate dehydrogenase (EC.1.3.99.1) in the areas of the nigro-striatal pathway during the ontogenesis of a pig

The development of activity of succinate dehydrogenase was investigated by histochemical methods under the light and electron microscopes and also by biochemical methods. The studies were carried out in the areas of the nigro-striatal pathways of 7 foetal groups, two day-old piglets, three week-old piglets and adult pigs. It was demonstrated that the activity of succinate dehydrogenase appeared first in foetuses of about 86 days (180 mm). The highest activity in prenatal development appeared just before birth in about 112 days old (260 mm) foetuses. After birth in 2 day-old piglets the activity of the examined enzyme decreases, while in 3 week-old it increases however not reaching the activity level observed in adult pigs.     

Mechanism of saikosaponin-d in the regulation of rat mesangial cell proliferation and synthesis of extracellular matrix proteins.

Glomerulosclerosis is a common disorder in many types of chronic kidney diseases. Previous studies have shown that glomerular mesangial cells (MCs) play an important role in the pathogenesis of glomerulosclerosis. The ability of saikosaponin-d (SSd) to reduce the damage of kidney in progressive glomerulosclerosis has been demonstrated. In this study, the effects of saikosaponin-d on MC proliferation and synthesis of extracellular matrix proteins were investigated. Rat MCs were isolated from Wistar rats and cultured in Dulbecco's modified Eagle's medium. MCs were challenged with lipopolysacchorides and incubated with different concentrations of SSd. Cell proliferation and cytotoxicity were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), flow cytometry, and lactate dehydrogenase assays. Type IV collagen, fibronectin, and TGF-beta1 in the conditioned medium were measured. The expression of cyclin-dependent kinase 4, c-Jun, and c-Fos was determined by immunohistochemistry. At a concentration of 4 microg/mL or lower, SSd inhibited MC proliferation but did not cause cell death. SSd also inhibited lipopolysaccharide-induced secretion of type IV collagen, fibronectin, and TGF-beta1 in MCs. Additionally, SSd reduced the expression of CDK4, c-Jun, and c-Fos in MCs. We conclude that SSd inhibited MC proliferation and synthesis of extracullular matrix proteins through the downregulation of the CDK4, c-Jun, and c-Fos genes.     

Human intestinal fibroblasts prevent apoptosis in human intestinal mast cells by a mechanism independent of stem cell factor, IL-3, IL-4, and nerve growth factor

In rodents, fibroblasts (FBs) mediate stem cell factor (SCF)-dependent growth of mast cells (MCs). In humans, SCF is mandatory for MC differentiation and survival. Other factors such as IL-3, IL-4, and nerve growth factor (NGF) act in synergism with SCF, thus enhancing proliferation and/or preventing apoptosis in MCs. In this study, we studied in vitro interactions between human MCs and human FBs, both isolated from the intestine and purified to homogeneity. In coculture with FBs, MCs survived for up to 3 wk, whereas purified MCs cultured alone died within a few days. TNF-alpha and IL-1beta, which both did not affect MC survival directly, enhanced FB-dependent MC growth. We provide evidence that FB-derived MC growth factors are soluble, heat-sensitive molecules which down-regulate MC apoptosis without enhancing MC proliferation. However, only low amounts of SCF were measured in FB-conditioned medium (<0.2 ng/ml). Moreover, blocking of SCF/c-kit interaction by anti-SCF or anti-c-kit Abs and neutralization of IL-3, IL-4, and NGF did not affect MC survival in the coculture system. In conclusion, our data indicate that human FBs promote survival of human MCs by mechanisms independent of SCF, IL-3, IL-4, and NGF. Such interactions between MCs and FBs may explain why MCs accumulate at sites of inflammatory bowel disease and intestinal fibrosis.     

Involvement of mast cells in monocrotaline-induced pulmonary hypertension in rats

Background

Mast cells (MCs) are implicated in inflammation and tissue remodeling. Accumulation of lung MCs is described in pulmonary hypertension (PH); however, whether MC degranulation and c-kit, a tyrosine kinase receptor critically involved in MC biology, contribute to the pathogenesis and progression of PH has not been fully explored.

Methods

Pulmonary MCs of idiopathic pulmonary arterial hypertension (IPAH) patients and monocrotaline-injected rats (MCT-rats) were examined by histochemistry and morphometry. Effects of the specific c-kit inhibitor PLX and MC stabilizer cromolyn sodium salt (CSS) were investigated in MCT-rats both by the preventive and therapeutic approaches. Hemodynamic and right ventricular hypertrophy measurements, pulmonary vascular morphometry and analysis of pulmonary MC localization/counts/activation were performed in animal model studies.

Results

There was a prevalence of pulmonary MCs in IPAH patients and MCT-rats as compared to the donors and healthy rats, respectively. Notably, the perivascular MCs were increased and a majority of them were degranulated in lungs of IPAH patients and MCT-rats (p < 0.05 versus donor and control, respectively). In MCT-rats, the pharmacological inhibitions of MC degranulation and c-kit with CSS and PLX, respectively by a preventive approach (treatment from day 1 to 21 of MCT-injection) significantly attenuated right ventricular systolic pressure (RVSP) and right ventricular hypertrophy (RVH). Moreover, vascular remodeling, as evident from the significantly decreased muscularization and medial wall thickness of distal pulmonary vessels, was improved. However, treatments with CSS and PLX by a therapeutic approach (from day 21 to 35 of MCT-injection) neither improved hemodynamics and RVH nor vascular remodeling.

Conclusions

The accumulation and activation of perivascular MCs in the lungs are the histopathological features present in clinical (IPAH patients) and experimental (MCT-rats) PH. Moreover, the accumulation and activation of MCs in the lungs contribute to the development of PH in MCT-rats. Our findings reveal an important pathophysiological insight into the role of MCs in the pathogenesis of PH in MCT- rats.     

High density of tryptase‐positive mast cells in human colorectal cancer: a poor prognostic factor related to protease‐activated receptor 2 expression

Tryptase(+) mast cells (MCs), abundant in the invasive front of tumours, contribute to tissue remodelling. Indeed, protease‐activated receptor‐2 (PAR‐2) activation by MC‐tryptase is considered an oncogenic event in colorectal cancer (CRC). Recently, we have suggested NHERF1 as a potential new marker in CRC. In this study, we aimed to determine the distribution of tryptase(+) MCs and PAR‐2 and to examine the relationship between PAR‐2 and NHERF1, investigating their reputed usefulness as tumour markers. We studied a cohort of 115 CRC specimens including primary cancer (C) and adjacent normal mucosa (NM) by immunohistochemical double staining, analyzing the protein expression of MC‐tryptase, PAR‐2 and cytoplasmic NHERF1. MC density was higher in NM than in C. Tumours with high TNM stage and poor grade showed the highest MC density. A higher PAR‐2 immunoreactivity characterized tumours most infiltrated by MCs compared with samples with low MC density. Furthermore, PAR‐2 overexpression was associated with advanced TNM stage, poor grade and lymphovascular invasion (LVI). A positive correlation existed between tryptase(+) MC density and PAR‐2 expression. Cytoplasmic NHERF1 was higher in C than in NM and overexpressing tumours resulted associated with nodal and distant metastases, poor grade and LVI. PAR‐2 correlated with cytoplasmic NHERF1 and the PAR‐2(+)/cytoplasmic NHERF1(+) expression immunophenotype identified tumours associated with unfavourable prognosis and aggressive clinical parameters. Our data indicate that the high density of tryptase(+) MCs at invasive margins of tumours was associated with advanced stages of CRC and was strongly correlated with PAR‐2 expression.     

Serglycin is essential for maturation of mast cell secretory granule

To address the biological function of the scarcely studied intracellular proteoglycans, we targeted the gene for serglycin (SG), the only known committed intracellular proteoglycan. SG-/- mice developed normally and were fertile, but their mast cells (MCs) were severely affected. In peritoneum there was a complete absence of normal granulated MCs. Furthermore, peritoneal cells and ear tissue from SG-/- animals were devoid of the various MC-specific proteases. However, mRNA for the proteases was present in SG+/+, SG+/-, and SG-/- tissues, indicating that SG is essential for the storage, but not expression, of the MC proteases. Experiments, in which the differentiation of bone marrow stem cells into mature MCs was followed, showed that secretory granule maturation was compromised in SG-/- cells. Moreover, SG+/+ and SG+/- cells, but not SG-/- cells, synthesized proteoglycans of high anionic charge density. Taken together, we demonstrate a key role for SG proteoglycan in MC function.