Total Number Of Mast Cells Research Articles

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

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.

Effect of Low-Level Laser Therapy on Mast Cells in Second-Degree Burns in Rats

This study sought to investigate whether low-level laser therapy (LLLT) with a helium-neon (He-Ne) laser would affect mast cell number and degranulation in second-degree burns in rats. LLLT has been recently applied to stimulate the wound healing process. Sixty-five rats were randomly allocated to one of five groups. A deep second-degree burn was inflicted on all rats except those in the control group. In the sham-exposed group burns remained untreated. In the two laser-treated groups, the burns were irradiated every day by LLLT, with energy densities of 1.2 and 2.4 J/cm(2). In the fifth group the burns were treated topically with 0.2% nitrofurazone cream every day. The unburned skin of the rats in the control group were used for baseline study. The effects on mast cell number and degranulation were assessed by counting the number of intact and degranulated mast cells in sections fixed in formalin and stained with toluidine blue. On the seventh and 16th days post-burn, the type 1 mast cell count in the 2.4-J/cm(2) laser-treated group was significantly higher than that of the control group. On the 30th day, the total numbers of mast cells in the laser-treated groups were lower than those in the control and sham-exposed groups. LLLT of deep second-degree cutaneous burns in rats significantly increased the number of intact mast cells during the inflammatory and proliferative phases of healing, and decreased the total number of mast cells during the remodeling phase.

Long-term alterations of colonic nerve–mast cell interactions induced by neonatal maternal deprivation in rats

Background: Neonatal maternal deprivation induces colonic alterations in adult rats, such as hypersensitivity to distension or an increase in paracellular permeability, characteristics of irritable bowel syndrome (IBS) patients. Recent studies...

The Efficacy of Montelukast and Airway Mast Cell Profiles in Patients with Cough Variant Asthma

Background. Cough variant asthma (CVA) is characterized by chronic cough without apparent wheezing; its pathophysiology is considered to be similar to that of classic asthma. Objective. The clinical effects of montelukast, a cysteinyl-leukotriene receptor antagonist, on cough variant asthma were assessed, and the activation profile of airway mast cells was examined. Methods. Montelukast (10 mg/day) was given orally to 36 CVA patients (25 women and 11 men; median age, 37.5 years). Before treatment, the patients' bronchial mucosa underwent a biopsy with a fiberoptic bronchoscope. The biopsy specimens were double stained with anti-CD63 antibody and anti-human tryptase antibody. Results. After 2 weeks of montelukast treatment, cough symptoms improved in 22 patients (the effective group) but did not improve in 14 patients (the ineffective group); in the ineffective group, the symptoms disappeared 2 weeks after they were switched to fluticasone propionate (400 μg/day) inhalation therapy. In the effective group, the time interval from the onset of symptoms to the initiation of treatment was significantly shorter than in the ineffective group. The bronchial mucosa biopsy specimens showed that the proportion of CD63-positive cells in tryptase-positive mast cells was significantly higher in the effective group than in the ineffective group; although the total numbers of mast cells were not different between the two groups. Conclusion. There is a subgroup of CVA patients in whom leukotrienes are closely involved in the pathogenesis of their chronic cough; activation of airway mast cells may be an essential feature in these patients.

Antigen inhalation induces mast cells and eosinophils infiltration in the guinea pig esophageal epithelium involving histamine-mediated pathway

Antigen challenge in sensitized guinea pig esophagus in vitro induces mast cell degranulation and histamine release. This study tests the hypothesis that antigen inhalation in vivo induces infiltration of the esophageal epithelium by mast cells and eosinophils via a histamine pathway. Actively sensitized guinea pigs were exposed to inhaled 0.1% ovalbumin. One or 24 h after inhalation exposure, the esophagus was processed for immunofluorescent staining of mast cell tryptase and eosinophil major basic protein (MBP). Additional animals were pretreated with thioperamide, a histamine H4/H3 receptor antagonist. Total tryptase- and MBP-labeled cells and percent of positive cells in the epithelial layer were counted. The total number of mast cells was unchanged after inhalation challenge, but the percentage in the epithelium increased 1 h after challenge. The total number of eosinophils increased 1 h after challenge, and the percentage migrating to the epithelium increased by 24 h after challenge. Mast cell migration into the mucosal epithelium preceded that of eosinophils. Thioperamide inhibited mast cell and eosinophil migration. In conclusion, antigen inhalation in sensitized animals induces mast cells and eosinophils to infiltrate in the esophageal epithelium via histamine-mediated mechanism.

Mast cells and eosinophils in invasive breast carcinoma

BackgroundInflammatory cells in the tumour stroma has gained increasing interest recently. Thus, we aimed to study the frequency and prognostic impact of stromal mast cells and tumour infiltrating eosinophils in invasive breast carcinomas.MethodsTissue microarrays containing 234 cases of invasive breast cancer were prepared and analysed for the presence of stromal mast cells and eosinophils. Tumour infiltrating eosinophils were counted on hematoxylin-eosin slides. Immunostaining for tryptase was done and the total number of mast cells were counted and correlated to the proliferation marker Ki 67, positivity for estrogen and progesterone receptors, clinical parameters and clinical outcome.ResultsStromal mast cells were found to correlate to low grade tumours and estrogen receptor positivity. There was a total lack of eosinophils in breast cancer tumours.ConclusionA high number of mast cells in the tumours correlated to low-grade tumours and estrogen receptor positivity. Eosinophils are not tumour infiltrating in breast cancers.

Culture of human mast cells from peripheral blood progenitors

This protocol details a method for obtaining a considerable number of human mast cells from peripheral blood cells from normal donors without using stem cell mobilization treatment. By using the magnetic cell sorting system, 10(4)-10(5) cells are retrieved in the CD34+ fraction when 100 ml of blood is drawn from a healthy donor. When these cells are cultured using methylcellulose medium supplemented with stem cell factor and interleukin 6, 10(3)-10(4) mast cell colonies are formed in 6 weeks. The total mast cell number at 6 weeks of culture will be 10(6)-10(7).

Comparison of human tonsillar mast cell localization and ultrastructural observations between IgE-mediated allergic and nonallergic donors

Mast cells (MCs) are important effector cells in mucosal defense and allergic inflammation. Lymphoid tissues such as tonsils and adenoids also have modest numbers of MCs. However, the role of MCs in lymphoid tissues is not well known. In this study, we showed the local distribution of MCs in tonsils from IgE-mediated allergic or nonallergic donors, studied their ultrastructure, and specified their surrounding cell types. Tonsils were obtained from IgE-mediated allergic or nonallergic donors suffering from chronic tonsillitis or hyperplastic tonsils. The localization and distribution of MCs and IgE binding to MCs were determined by immunohistochemistry using antibodies against tryptase, c-kit, and IgE. In addition, mast cell structure was examined using electron microscopy. In both allergic and nonallergic donors, MCs were distributed mainly in the interfollicular area and the perivascular area of connective tissue. We found that the total number of MCs in tonsils was almost the same in both donor groups. However, the number of MCs in the interfollicular area was significantly higher in nonallergic versus allergic donors. Moreover, the electron microscopy revealed that MCs localized in perivascular areas of connective tissue have scroll-type granules, and MCs in the interfollicular areas contained both particle and scroll-type granules. In addition, the MCs that were surrounded by CD4+ lymphocytes in the interfollicular area showed empty granules, whereas MCs in the perivascular area, not surround by CD4+, were intact. This implies that these MCs were degranulated, and this probably was caused by CD4+ cells. Taken together, these findings suggest that tonsillar MCs distribute differently in allergic and nonallergic donors, and that MCs in the interfollicular area might be activated by direct contact with CD4+ T cells.

Gene and protein expression of protease‐activated receptor 2 in structural and inflammatory cells in the nasal mucosa in seasonal allergic rhinitis

Protease-activated receptor 2 (PAR 2) has been shown to be responsible for trypsin and mast cell tryptase-induced airway inflammation. Here, the present study aimed to explore the expression of PAR 2 in the nasal mucosa of seasonal allergic rhinitis (SAR). Study subjects were recruited for the study by medical history, physical examination and laboratory screening tests. Using immunohistochemistry, laser-assisted cell picking and subsequently real-time PCR, nasal mucosa biopsies of SAR patients were investigated for PAR 2 gene and protein expression in complex tissues of the nasal mucosa. Gene and protein expression of PAR 2 was firstly detected in nasal mucosa of SAR patients. The relative gene expression level of PAR 2 was significantly increased in complex tissues of the nasal mucosa of SAR (6.21+/-4.02 vs. controls: 1.38+/-0.86, P=0.004). Moreover, PAR 2 mRNA expression in epithelial cells (SAR: 4.78+/-4.64 vs. controls: 0.84+/-0.61, P=0.003) but not in mucus (SAR: 1.51+/-1.15 vs. controls: 1.35+/-1.02, P=0.78) and endothelial cells (SAR: 1.20+/-0.57 vs. controls: 1.73+/-1.30, P=0.5) was found to be significantly changed in the nasal mucosa in SAR. Using double immunohistochemistry the present study demonstrated that the total numbers of mast cells (P=0.0003) and eosinophils (P=0.03) and the numbers of eosinophils expressing PAR 2 (P=0.006) were significantly elevated in the nasal mucosa of SAR compared with the controls. The abundant presence and distribution of gene and protein expression of PAR 2 in different cell types in the nasal mucosa under normal situation, the increased expression of PAR 2 in epithelial cells and the increased number of eosinophils with PAR 2 suggest that PAR 2 may contribute to the pathogenesis of allergic diseases such as SAR.

Endometrial chemokines, uterine natural killer cells and mast cells in long-term users of the levonorgestrel-releasing intrauterine system

The objective was to assess endometrial chemokines in users of the levonorgestrel-releasing intrauterine system (LNG-IUS) and correlate them with leucocyte populations, uterine natural killer cells (uNK) and mast cells (MCs). Endometrium was obtained from two groups of women who had been using LNG-IUS for 3 years or more: 11 amenorrhoeic women formed the non-bleeding group and 15 women who maintained some form of cyclic bleeding comprised the bleeding group. Specific antibodies were used for the assessment of neutrophils, uNK cells and MCs. Immunohistochemistry was performed to locate the chemokines 6Ckine and interleukin-8 (IL-8). Neutrophils were few and without differences between the two groups. uNK cells were significantly higher in the bleeding group (P < 0.0001). There was no difference between the total number of MCs and activated MCs, but there was a greater extracellular area stained for MC tryptase (P < 0.05). Chemokines 6CKine and IL-8 were abundant in the stroma and in the epithelium, and there was no difference between the groups. We observed more uNK cells in users with bleeding and a greater extracellular area stained for MC tryptase, although there were no differences between the number of MCs and activated MCs or the chemokines 6CKine and IL-8. uNK cells and MC products may play a role in provoking breakthrough bleeding in long-term users of the LNG-IUS.

Mast cell activation and degranulation occur early during induction of periosteal bone resorption

We have previously postulated that mast cells participate in the cellular network involved in osteoclastic resorption, probably through histamine release. In this study, we examined mast cell activation and histamine release during origination of resorption. Groups of 10 rats were killed 0, 0.5, 1, 1.5, 3, 6, 9, 12 and 18 h after induction of resorption in a synchronized model of cortical resorption along the mandible. The total number of mast cells was transiently decreased by about one-third at 1 and 9 h. Mast cell activation was monitored by Alcian blue–safranin staining. Early after induction, mast cells started to release their mediator stores; complete release led to the apparent disappearance of the cells with the staining technique used. Histamine immunostaining confirmed the release of histamine and its diffusion in the extracellular environment. Massive degranulation was observed at 1.5 and 9 h with toluidine blue staining. Cell recovery, assessed in terms of histidine decarboxylase expression, occurred gradually. The number of ED1 + osteoclast precursors strongly increased from 12 h up to 18 h. Most parameters had returned to baseline at 18 h, except the ED1 + cells. H 2 receptor inhibition with famotidine strongly decreased ED1 + osteoclast precursors at 12 h and subsequently osteoclasts at the peak of resorption. These data support a role of mast cells in resorption origination. They show an early and transient intervention of mast cells in the events regulating the recruitment of circulating osteoclast precursors and ultimately of resorption. Mast cell activation and degranulation induce the release of mediators, particularly histamine acting through its H 2 receptors, which are likely involved in these reactions.

The majority of brain mast cells in B10.PL mice is present in the hippocampal formation

In the healthy mammalian CNS, mast cells (MCs) are thought to be located mostly in the thalamus. In this study, we have systematically assessed the presence of MCs in the hippocampal formation (HF) and in the thalamus of normal male and female B10.PL mice. Giemsa + and Toluidine Blue + MCs were detected by histomorphometric analyses at perivascular and intraparenchymal sites of both the hippocampus and the entorhinal cortex. We found a mean number of 4.4 MCs in the HF of female and 3.3 MCs in male B10.PL mice. In contrast to the HF, no MCs were present in the thalamus of these mice. Notably, all HF-MCs showed immunoreactivity for Kit, the receptor for the MC growth and maturation factor SCF, as assessed by FITC–avidin/Kit double labelling. We demonstrate that the majority of brain MCs is found in the hippocampus and entorhinal cortex of B10.PL mice, though the total number of MCs is small compared to other mouse strains or rats. The presence of most brain MCs in the HF of B10.PL mice suggests a potential role of MCs in hippocampal physiology and pathology.

Mast cell numbers and protease expression patterns in biopsy specimens following renal transplantation from living‐related donors predict long‐term graft function

In human kidney transplantation the main cause of declining long-term graft function is chronic allograft nephropathy (CAN). Recent studies have implicated human mast cells (MC) in chronic inflammation and fibrosis, MC can be subtyped according to protease content: MC(T) containing tryptase only and MC(TC) containing both tryptase and chymase. We investigated immunohistochemically whether numbers and subtypes of MC in biopsy specimens 100 d after transplantation could predict subsequent fibrosis and graft dysfunction. The total number of MC/high-power field at 100 d after transplantation correlated significantly with change in creatinine clearance (DeltaCcr), defined as (Ccr at 100 d) - (Ccr at 3 yr) (R = 0.597, p = 0.0021); fibrosis index (FI) at 100 d (R = 0.583, p = 0.0066); and DeltaFI, defined as (FI at 3 yr) - (FI at 100 d) (R = 0.406, p < 0.05). The ratio of MC(TC) to total MC at 100 d also correlated with DeltaCcr (R = 0.491, p = 0.0148), FI at 100 d (R = 0.527, p = 0.0081), and DeltaFI (R = 0.417, p < 0.05). Thus, increases in number of total MC and the ratio of MC(TC) to total MC in early biopsy specimens were related to decline of long-term graft function and fibrosis.

RELATIONSHIP BETWEEN MAST CELL AND INOS EXPRESSION IN TESTICULAR TISSUE ASSOCIATED WITH INFERTILITY

The objective of this study was to investigate mast cells and iNOS expression in testis tissue, and to correlate these results with spermatogenic disorders. A total of 136 testicular biopsies were obtained from the testes of 80 patients with infertility. Their age ranged from 21 to 45 years. The biopsy specimens were immunohistochemically stained with antihuman tryptase for mast cells. In each section, all interstitial fields were evaluated for the total number of mast cells as well as the total number of Leydig cells. The number of mast cells per Leydig cell was calculated and recorded as mast cell index. Immunohistochemical iNOS staining was evaluated semiquantitatively according to intensity and the proportion of the stained cells. There was a significant increase of the mast cell index in all groups with testicular disorder compared with normal spermatogenesis group (p < 0.05). Increase of the index was in the order of hypospermatogenesis, maturation arrest and SCO, and index of SCO group was especially higher, i.e, more than twice than other groups. iNOS score was significantly higher in the SCO group than in the men with normal spermatogenesis, hypospermatogenesis, and maturation arrest (p < 0.05). Finally, a significantly statistical correlation was found between the iNOS score and mast cells index (r = 0.758, p = 0.001). Increase of mast cell index was observed in the groups of infertile testis, and high expression of iNOS in Leydig cells was associated with the highest mast cell index in SCO, the lesion with the most severe damage of the germ cell.

Interaction between isolated human myocardial mast cells and cultured fibroblasts 1

Introduction Previously, we reported an increase in interstitial collagen and total mast-cell numbers in heart failure versus normal myocardium. A secondary increase, primarily in chymase-negative mast cells, occurred following LVAD support compared to matched pre-LVAD tissue samples and was associated with a decrease in interstitial collagen and bFGF. To further elucidate the changes in interstitial collagen, we investigated the direct interaction between mast cells, isolated from failing myocardium with or without previous LVAD support, and human fibroblasts in a coculture model. Additionally, the expression of HSP-47, the pro-collagen-specific chaperone protein, was determined in the particular myocardium. Materials and methods Myocardial tissue was obtained from 10 patients with end-stage dilated cardiomyopathy (DCM) at the time of transplantation. Five patients were transplanted following LVAD support, five patients without previous LVAD support. Mast cells were isolated according to a standard protocol, including collagenase digestion and cell separation. The isolated mast cells were co-cultured with human fibroblasts for 12 h, with or without stimulation of degranulation, and protein synthesis was measured by [ 3H]-proline incorporation. HSP-47 immunostaining was performed in the different myocardial samples and the positive cells were quantified. Results Stimulated mast cells isolated from DCM tissue (without previous LVAD support) caused a 92% increase in [ 3H]-proline incorporation and consequently in protein production in fibroblasts compared to mast-cell free culture ( P < 0.01), while conversely stimulated mast cells isolated from LVAD supported myocardium decreased the [ 3H]-proline incorporation by 63% ( P < 0.01) below baseline. Nonstimulated mast cells did not significantly alter the protein production over baseline. There was also a significant increase in the number of HSP-47-positive cells in DCM myocardium compared to normal ( P < 0.01) and there was a shift toward normal after LVAD support ( P < 0.01). Conclusion We demonstrate that fibroblast protein production in vitro is significantly altered by mast cells and that the direction of change is dependent on whether myocardium was supported by LVAD. We suggest that under long-term LVAD support there is a phenotypic alteration in myocardial mast cells, which leads to a change in concentration and/or composition of mediators, capable of re-remodeling the myocardial matrix.

Proliferation of Protease-enriched Mast Cells in Sarcoptic Skin Lesions of Raccoon Dogs

Skin sites, tongue, lung, liver, jejunum and rectum from two raccoon dogs with Sarcoptes scabiei infestation and five normal (control) raccoon dogs were examined in terms of the distribution, proteoglycan properties and protease activity of mast cells. Infestation with S. scabiei caused a significant increase in the number of dermal mast cells. While the number of mast cells (average±standard deviation) in specimens of skin from the dorsum, dorsal neck, dorsal hind foot and dorsal fore foot was 40.0±19.8/mm 2 in control animals, it was 236.1±58.9/mm 2 in the skin of mange-infested animals. Histochemical analysis revealed the glycosaminoglycan, heparin, within the mast cells of all organs examined in both control and affected animals. Enzyme-histochemical detection of serine proteases demonstrated an increase in mast-cell-specific protease activity (i.e., chymase and tryptase) in the skin of infested animals. The percentage of mast cells demonstrating chymase activity was 53.0±27.4% in control animals and 73.8±19.4% in mite-infested animals. The corresponding results for tryptase activity were 53.5±25.2% and 89.4±9.8%. Increases in mast cell chymase or tryptase activity, or both, were also observed within other organs of the infected animals, but the total number of mast cells found at such sites (with the exception of liver and ventrolateral pinna) did not differ from those of control animals.

Mast Cells and Hemangioma

Hemangioma is a primary tumor of the microvasculature in which angiogenesis is initially excessive, followed by spontaneous regression of the newly formed vessels, with the cellular parenchyma gradually being replaced with fibrofatty tissue. Mast cells, which are highly heterogenous in terms of their morphology, function, and metabolic products, have been implicated in the pathophysiology of hemangioma. Csaba stain shows that mast cells are predominantly of the biogenic amine phenotype throughout the development of hemangioma. The predominance of this phenotype remains unaltered following successful steroid therapy, although their number increases fourfold. Mast cells, all of which stain positive for tryptase, and those that stain positive for chymase as well, have been identified in hemangioma biopsy specimens throughout the three developmental phases. The total number of mast cells is highest during the involuting phase, less in the involuted phase, and least in the proliferative phase. The proportion of mast cells that contain both tryptase and chymase decreases from the proliferative through involuting to the involuted phase. This decreasing proportion of mast cells that contain both tryptase and chymase with ongoing involution parallels that of progressive deposition of the extracellular matrix as indicated by increasing fibrosis and fatty deposition. The short-chain type VIII collagen, thought to play a key role in angiogenesis, has been detected throughout the developmental phases of hemangioma. It has been postulated that this collagen, which is produced early in new vessel development, provides a substratum to facilitate the migration of endothelial cells. It may also facilitate the deposition of other extracellular constituents and influence cell movement and the maintenance of cell phenotypes. The intracellular localization of type VIII collagen in mast cells only in the early proliferative phase suggests that there is an active synthesis by mast cells during this phase. The increasing extracellular localization during hemangioma development may be caused by an increased secretion of protein from intracellular stores. The increased number of mast cells during the involuting phase indicates that these cells may play a role in the regression of hemangioma. This is in contrast to the large body of evidence showing the proangiogenic role of mast cells. The proportion of proliferating mast cells decreases, whereas the proportion of mast cells positive for clusterin/apolipoprotein J increases with ongoing involution of hemangioma. Clusterin/apolipoprotein J expression has been considered as a prominent marker of apoptotic cell loss. The presence of clusterin/apolipoprotein J granules both in the adjacent endothelial cells and in capillary lumens suggests that mast cells may be secreting this apoptotic modulator to promote the regression of hemangioma. Certain effectors produced by mast cells may participate in the development of hemangioma. It has been proposed that one of the functions of mast cells is to release factors leading to the regression of hemangioma. The evidence suggests that although mast cells may have a function in the endothelial proliferation in hemangioma, they also play a crucial role in the regression of this tumor. However, the roles of mast cells in the life cycle of hemangioma are likely to be complex and may involve stimulators of angiogenesis in the proliferative phase but inhibitors in later phases.

Naloxone-induced morphine withdrawal increases the number and degranulation of mast cells in the thalamus of the mouse

Naloxone-induced jumping in morphine-dependent mice is inhibited by cromolyn, a mast cell stabilizer, suggesting that this characteristic withdrawal behavior results from degranulation of mast cells. Because withdrawal is considered as a central phenomenon, degranulation of mast cells located within the CNS may influence aspects of opioid withdrawal. The present study evaluates histologically whether naloxone, injected into opioid dependent mice, induces degranulation of mast cells. Seventy-two hours after the s.c. implantation of a 75 mg morphine pellet, the number and degranulation of thalamic mast cells did not differ from those in placebo-implanted controls. However, two injections of 50 mg/kg of naloxone, 30 and 60 min before tissue collection, increased the number of degranulated mast cells compared to those in mice injected with saline. Analysis throughout the entire thalamus (90 40-μ sections) revealed increases in the total number of mast cells as well as the number that were degranulated, especially in sections 52–60, corresponding to Bregma −2.18 to 2.54. Here, mast cells were clustered in the IGL and VPL/VPM nuclei, and redistributed from the ventromedial to the dorsolateral aspects of the Po and PF nuclei during withdrawal. Degranulation was also greater throughout the LD, LP nuclei during withdrawal. These data reveal a novel neuroimmune reaction to opioid withdrawal in the CNS.

Interaction between isolated human myocardial mast cells and cultured fibroblasts

Introduction: Previously, we reported an increase in interstitial collagen and total mast cell numbers in heart failure versus normal myocardium. A secondary increase, primarily in chymase-negative mast cells, occurred following LVAD-support compared to matched pre-LVAD tissue samples and was associated with a decrease in interstitial collagen and bFGF. We investigated the direct interaction between mast cells, isolated from failing myocardium with or without previous LVAD support, and human fibroblasts in a co-culture model. Methods: Myocardial tissue was obtained from 10 patients with endstage dilated cardiomyopathy (DCM) at the time of transplantation. Five patients were transplanted following LVAD support, five patients without previous LVAD support. Mast cells were isolated according to a standard protocol, including collagenase digestion and cell separation. The isolated mast cells were co-cultured with human fibroblasts for 12 hours, with or without stimulation of degranulation and protein synthesis was measured by [3H]-proline incorporation. Results: Mast cells isolated from unsupported DCM tissue caused a 92% increase in [3H]-proline incorporation in fibroblasts after stimulation compared to mast cell free culture (p < 0.01), while mast cells isolated from LVAD supported myocardium decreased the [3H]-proline incorporation by 63% (p < 0.01) and consequently the protein production. Unstimulated mast cells did not significantly alter the protein production over baseline. Conclusion: We demonstrate that fibroblast protein production in vitro is significantly altered by mast cells and that the direction of change is dependent on whether myocardium was supported by LVAD. We suggest, that under long-term LVAD support there is a phenotypic alteration in mast cells, which leads to a change in mediators’ concentration and/or composition, capable of re-remodeling the myocardial matrix.

Mast cell subsets and neuropeptides in leprosy reactions.

The immunohistochemical identification of neuropeptides (calcitonin gene-related peptide, vasoactive intestinal polypeptide, substance P, alpha-melanocyte stimulating hormone and gamma-melanocyte stimulating hormone) quantification of mast cells and their subsets (tryptase/chymase-immunoreactive mast cells = TCMC and tryptase-immunoreactive mast cells = TMC) were determined in biopsies of six patients with leprosy reactions (three patients with type I reaction and three with type II). Biopsies were compared with those taken from the same body site in the remission stage of the same patient. We found a relative increase of TMC in the inflammatory infiltrate of the reactional biopsies compared to the post-reactional biopsy. Also, the total number of mast cells and the TMC/TCMC ratio in the inflammatory infiltrate was significantly higher than in the intervening dermis of the biopsies of both periods. No significant difference was found regarding neuroptide expression in the reactional and post-reactional biopsies. The relative increase of TMC in the reactional infiltrates could implicate this mast cell subset in the reported increase of the immune response in leprosy reactions.