Mast cells, fibroblasts, and fibrosis. New clues to the riddle of mast cells

Acute suppression of TGF-ß with local, sustained release of tranilast against the formation of fibrous capsules around silicone implants

We propose the acute, local suppression of transforming growth factor beta (TGF-ß), a major profibrotic cytokine, to reduce fibrosis around silicone implants. To this end, we prepared silicone implants that were able to release tranilast, a TGF-ß inhibitor, in a sustained manner for 5 days or 15 days. We performed histologic and immunohistochemical analyses for 12 weeks after the implantation of the implants in living rats. The capsule thicknesses and collagen densities significantly decreased compared with those around the non-treated silicone implants. Notably, early suppression of TGF-ß affected the fibrogenesis that actually occurs at the late stage of wound healing. This change may be ascribed to the decrease in monocyte recruitment mediated by early TGF-ß during the acute inflammatory reaction. Thus, a significant decrease in differentiated macrophages was observed along with a decrease in the quantity of TGF-ß and fibroblasts during the subsequent inflammation stage; these changes led to a diminished fibrotic capsule formation.

Altered immunohistochemical expression of mast cell tryptase and chymase in the pathogenesis of oral submucous fibrosis and malignant transformation of the overlying epithelium

Mast cells (MCs) expressing serine proteases; tryptase and chymase, are associated with fibrosis in various diseases. However, little is known about their involvement in oral submucous fibrosis (OSF). Our goal was to evaluate the role of MC tryptase and chymase in the pathogenesis of OSF and its malignant transformation. Immunohistochemical expression of MC tryptase and chymase was evaluated in 20 cases of OSF, 10 cases of oral squamous cell carcinoma (OSCC) and 10 cases of healthy controls. Subepithelial zone of Stage 1 and 2 while deep zone of Stage 3 and 4 OSF demonstrated increased tryptase positive MCs. OSCC revealed a proportionate increase in tryptase and chymase positive MCs irrespective of areas of distribution. An altered balance in the subepithelial and deep distribution of tryptase and chymase positive MCs play an important role in the pathogenesis of OSF and its malignant transformation.

Dynamic mast cell-stromal cell interactions promote growth of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) exists in a complex desmoplastic microenvironment, which includes cancer-associated fibroblasts [also known as pancreatic stellate cells (PSC)] and immune cells that provide a fibrotic niche that impedes successful cancer therapy. We have found that mast cells are essential for PDAC tumorigenesis. Whether mast cells contribute to the growth of PDAC and/or PSCs is unknown. Here, we tested the hypothesis that mast cells contribute to the growth of PSCs and tumor cells, thus contributing to PDAC development. Tumor cells promoted mast cell migration. Both tumor cells and PSCs stimulated mast cell activation. Conversely, mast cell-derived interleukin (IL)-13 and tryptase stimulated PSC proliferation. Treating tumor-bearing mice with agents that block mast cell migration and function depressed PDAC growth. Our findings suggest that mast cells exacerbate the cellular and extracellular dynamics of the tumor microenvironment found in PDAC. Therefore, targeting mast cells may inhibit stromal formation and improve therapy.

Dermal mast cell density in fingers reflects severity of skin sclerosis in systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is characterized by skin sclerosis, which develops from the distal extremities and spreads to the trunk. Although several reports have implied the involvement of mast cells in SSc based on examination of forearm skin specimens, there have been no studies that examined digital skin specimens.

METHODS

Skin biopsies were obtained from the distal one-third of the forearm and between distal and proximal interphalangeal joints from 46 SSc patients, as well as from 29 non-SSc patients and normal controls. Dermal mast cells were detected histologically using NanoZoomer digital pathology.

RESULTS

Dermal mast cell density was significantly higher in both the forearms and fingers in SSc patients compared with non-SSc patients and normal controls. Digital dermal mast cell density was significantly higher in patients with diffuse cutaneous SSc than in local cutaneous SSc patients and also in the anti-topoisomerase I antibody-positive group than in the negative group, though such tendency was not noted in the forearm dermis. Interestingly, digital dermal mast cell density tended to correlate negatively but significantly with disease duration, suggesting the possible involvement of dermal mast cells in the early pathological process.

CONCLUSION

Digital accumulation of toluidine blue- and/or c-Kit-positive dermal mast cells appears to be involved in the early stages of the pathological processes of SSc, especially in patients positive for anti-topoisomerase I antibody.

Immunohistochemical study of the presence of mast cells in idiopathic orbital inflammatory pseudotumor: possible role of mast cells in the course of its pathogenesis

BACKGROUND

It is well known that mast cells (MC) are involved in fibrosis and many forms of chronic inflammation. Chronic inflammatory cells infiltration and fibrosis in various orbital tissues are the main histopathologic features in patients with idiopathic orbital inflammatory pseudotumor (IOIP). Whether MC is involved in the course of chronic inflammatory conditions of IOIP is not yet clear. We sought to investigate the distribution of MCs in samples of IOIP and to explore the possible role of MC in the course of its pathegenesis.

METHODS

Immunohistochemistry with tryptase monoclonal antibody (a specific mast-cell surface marker) was used in 53 different subtypes of IOIP specimens including 19 of the lymphocyte infiltrative type, 22 of the fibrotic type, 12 of the mixed type and 4 specimens of normal orbital tissue. The number of positive stained MC was counted by light microscopy. The differences of the number of MC between various subtypes of IOIP were analyzed.

RESULTS

The average number of positive stained MC in the normal control group was 33.33 +/- 4.72 /mm(3), whereas the average numbers of positive stained MC in the lymphocyte infiltrative subtype group, the mixed subtype group and the fibrotic subtype group were 306.35 +/- 55.81 /mm(3), 662.93 +/- 115.28 /mm(3) and 813.44 +/- 146.56 /mm(3), respectively. Compared with the normal control, the number of MC increased significantly in all three subtypes of IOIP samples (P < 0.01). The number of MC in fibrotic subtype IOIP was the largest, followed by mixed subtype IOIP, and the lymphocyte infiltrative subtype IOIP (P < 0.05). The MC were distributed mainly around small vessels and in collagen fibers.

CONCLUSION

Mast cells may play an underappreciated role in the fibrosis of IOIP.

Histology of the thick scar on the female, red Duroc pig: final similarities to human hypertrophic scar

The etiology and treatment of hypertrophic scar remain puzzles even after decades of research. A significant reason is the lack of an accepted animal model of the process. The female, red Duroc pig model was described long ago. Since the skin of the pig is similar to that of humans, we are attempting to validate this model and found it to be encouraging. In this project we quantified myofibroblasts, mast cells and collagen nodules in the thick scar of the Duroc pig and compared these to the values for human hypertrophic scar. We found the results to be quite similar and so further validated the model. In addition, we observed that soon after wounding an inflammatory cell layer forms. The thickness of the inflammatory layer approaches the thickness of the skin removed as if the remaining dermis "knows" how much dermis is gone. In deep wounds this inflammatory layer thickens and this thickness is predictive of the thickness of the ultimate scar.

Protease-Activated Receptor-2 (PAR-2) Expression in Human Fibroblasts is Regulated by Growth Factors and Extracellular Matrix

Many cell types express a membrane receptor, activated by trypsin-like proteases, termed protease-activated receptor-2 (PAR-2). Previous studies describing PAR-2 expression on fibroblasts have been conflicting. In this report, we investigated in vitro PAR-2 expression on several fibroblast cell lines using flow cytometry, immunohistology, and immunoblots of cell lysates. Consistent PAR-2 expression was detected in cultured fibroblasts, although we observed heterogeneity of cellular expression among the cell lines. Some fibroblast lines expressed PAR-2 predominantly as an intracellular protein with differing cytoplasmic staining patterns, whereas other fibroblast lines displayed PAR-2 primarily as a cell surface receptor. Immunoblots of cell lysates with polyclonal anti-PAR-2 demonstrated a 44 kDa band, the predicted molecular weight for the PAR-2 core protein. Furthermore, we noted that expression of PAR-2 was subject to regulation. Fibroblasts grown within a collagen matrix downregulated receptor expression whereas increased PAR-2 expression was observed by the addition of fibroblast growth factors PDGF-BB and TGF-beta. This study may explain the previous inconsistencies in PAR-2 expression observed on tissue fibroblasts. Results indicate that the degree of fibroblast proliferation, attenuated by extracellular matrix and upregulated by growth factors, influences whether fibroblasts express PAR-2 and, thus, would be responsive to protease signaling.

Proliferative funiculitis with a prominent infiltration of mast cells

A surgical case of proliferative funiculitis (pseudosarcomatous myofibroblastic proliferation of the spermatic cord) with a prominent mast cell infiltration is reported. A 67-year-old man with a history of right inguinal herniorrhaphy 7 years earlier was operated on for diffuse swelling of the inguinal region and scrotum. A large lipoma was found in the inguinal region, and a nodular lesion, measuring 2.7 cm in maximal dimension, was firmly attached to the right spermatic cord. The nodular lesion showed diffuse proliferation of fibroblasts and myofibroblasts associated with the deposition of collagen. A diffuse infiltration of numerous mast cells was found throughout the lesion. Lesions that belong to the group of inflammatory pseudotumors are rarely accompanied by a prominent mast cell infiltration, and the differentiation from mast cell neoplasms is often problematic in such cases. The present case is the first example of proliferative funiculitis associated with this rare phenomenon.

Histamine-induced cytokine production and ICAM-1 expression in human conjunctival fibroblasts

PURPOSE

Conjunctival fibroblasts stimulated with histamine (H) may be directly involved in the inflammatory and remodeling processes of chronic allergic conjunctival diseases.

METHODS

Proinflammatory cytokine and growth factor production, and the expression of intercellular adhesion molecule-1 (ICAM-1) were studied in conjunctival fibroblast cultures challenged with different concentrations of H (from 10(-9) M to 10(-) (4) M). Interleukin (IL)-1, IL-4, IL-6, IL-8, tumor necrosis factor-alfa (TNF-alpha), fibroblast growth factor (FGF), epidermal growth factor (EGF) and transforming growth factor-beta (TGFbeta-1) were measured in supernatants. ICAM-1 expression was evaluated by a fluorescence activated cell sorter (FACS). Inhibitory effects of the H-1 antagonists (antiH): emedastine, levocabastine, and azelastine, and of the antiH-2, cimetidine, on H-stimulated fibroblasts were evaluated by measuring both cytokines in supernatants and the cellular expression of ICAM-1.

RESULTS

Histamine increased the production of IL-1, IL-6 and IL-8, and ICAM-1 expression. TNF-alpha, IL-4 and growth factor production were not modified by histamine. The antiH-1, emedastine, significantly reduced H-induced production of IL-1, IL-6 and IL-8, while azelastine reduced only IL-1. Levocabastine and cimetidine were less effective. The histamine-induced increase in ICAM-1 expression was inhibited by emedastine but not by azelastine and levocabastine.

CONCLUSIONS

Histamine has pro-inflammatory effects on conjunctival fibroblasts, inducing the production of cytokines and the expression of ICAM-1. Emedastine significantly reduced cytokine and ICAM-1 expression from H-stimulated fibroblasts. Conjunctival fibroblasts may contribute to the maintenance of inflammation in chronic allergic diseases.

The mast cell in wound healing

This review describes the role of the mast cell in the pathobiology of skin healing. After illustrating its main morphofunctional characteristics, with special reference to the dog and cat, we consider the involvement of the mast cell in the various phases of skin repair. With the aid of a wide array of newly formed or preformed mediators released by degranulation, the activated mast cell controls the key events of the healing phases: triggering and modulation of the inflammatory stage, proliferation of connective cellular elements and final remodelling of the newly formed connective tissue matrix. The importance of the mast cell in regulating healing processes is also demonstrated by the fact that a surplus or deficit of degranulated biological mediators causes impaired repair, with the formation of exuberant granulation tissue (e.g. keloids and hypertrophic scars), delayed closure (dehiscence) and chronicity of the inflammatory stage.

The differentiation and function of myofibroblasts is regulated by mast cell mediators

Myofibroblasts are fibroblasts that express certain features of smooth muscle differentiation. Increased numbers of myofibroblasts and mast cells are frequently found together in a wide variety of settings, such as normal wound repair and scleroderma skin, which suggests that mediators produced by the mast cells could play a role in the regulation of myofibroblast differentiation and function. We used a human mast cell line, HMC-1, to determine if mast cells can induce normal human dermal fibroblasts to differentiate into functional myofibroblasts in vitro. We monitored the differentiation process by assaying two properties of the myofibroblast phenotype: expression of alpha-smooth muscle actin and functional capacity to contract a collagen matrix. In both a simple coculture system and in a skin-equivalent culture system, HMC-1 cells induced alpha-smooth muscle actin expression by fibroblasts. HMC-1 cells also stimulated fibroblast contraction of collagen gels, and the relative amount of contraction was dependent upon the number of HMC-1 cells present. To characterize the individual contributions made by specific mast cell products, we examined the effects of histamine, tumor necrosis factor alpha, and tryptase. Histamine induced a clear increase in alpha-smooth muscle actin expression, but it did not appear to stimulate fibroblast contraction. Tumor necrosis factor alpha had no effect in either assay. Purified human tryptase induced alpha-smooth muscle actin expression, and blocking the proteolytic activity of tryptase with specific inhibitors reduced that response. Tryptase inhibitors also eliminated the ability of HMC-1 cells to stimulate fibroblast contraction, suggesting that tryptase secreted by the HMC-1 cells may be one of the active mast cell mediators.

Mast cell tryptase does not alter matrix metalloproteinase expression in human dermal fibroblasts: further evidence that proteolytically-active tryptase is a potent fibrogenic factor

There is compelling in vitro and in vivo evidence to implicate mast cells in the development of fibrosis. However, an important question remains as to the mechanisms by which mast cells mediate fibrosis. Recent evidence from our laboratory (Gruber et al., 1997, J. Immunol. , 158:2310-2317) has revealed that tryptase, the unique and abundant serine protease of human mast cells, is capable of activating fibroblasts by stimulating chemotaxis, proliferation, and procollagen mRNA synthesis. Regulation of matrix metalloproteinase (MMP) expression is another key step in connective tissue remodeling. Therefore, the effect of tryptase on fibroblast MMP expression was investigated. Proteolytically active tryptase did not alter the cellular mRNA levels for fibroblast MMP-1, MMP-2, MMP-3, and MMP-9 as detected by RNase protection assays. Moreover, tryptase did not alter the basal levels of MMP-1, MMP-2, MMP-3, MMP-9, or the tissue inhibitor of MMP-1 (TIMP-1) in fibroblast conditioned media as detected by specific enzyme-linked immunosorbent assay (ELISA). These results indicate that tryptase does not increase MMP expression in normal dermal fibroblasts. Moreover, these data strengthen the potential role of this unique serine protease as a potent fibrogenic factor.

Immunopathology of the human hair follicle

Although patients are told that, in many instances, their hair loss is precipitated by stress, they are certainly stressed and saddened by their alopecia. They would be elated with the ability to regrow their hair. Ideally, therapy would be specific and targeted at the cascade of inflammatory, cytokine-mediated, and mesenchymal events which lead to hair loss. Such is the case with infectious folliculitides: Pityrosporum folliculitis is cleared with antifungal agents, bacterial folliculitis is cleared with antibiotics, and herpetic folliculitis is treated with antiviral agents. Future studies of the hair follicle will perhaps unlock the mechanisms that drive and maintain normal hair growth. Until that time scientists will, no doubt, continue to be fascinated by the intricate developmental and immunologic mechanisms that drive this micro-organ of the skin.

Histamine effects on conjunctival fibroblasts from patients with vernal conjunctivitis

Histamine, an important mast cell mediator in allergic disorders, may affect extracellular matrix production and cell growth in vernal keratoconjunctivitis (VKC). In the present study, the histamine reactivity of conjunctival fibroblasts derived from VKC patients was investigated in vitro. Conjunctival fibroblast cultures were derived from biopses of 8 tarsal VKC patients and 5 normal subjects. These cells were maintained in vitro and stimulated with different concentrations of histamine with and without H1 (clorpheniramine) and H2 (cimetidine) receptor antagonists. Comparisons were made to fibroblasts grown in the same media without histamine and to fibroblasts stimulated with just antihistamine. The effects of histamine were evaluated by: (1) the MTT test to assess cell proliferation; (2) an in vitro wound model for cell migration and (3) the measurement of procollagen I (PIP) and procollagen III (PIIIP) in supernatants for collagen production. Results showed: (1) While VKC-derived fibroblasts proliferated at a faster rate than normal cells in unstimulated media, after histamine stimulation, VKC and normal cells grew at a similar rate. Both H1 and H2 antagonists significantly inhibited (P<0.05) histamine-induced cell proliferation. (2) Histamine enhanced cell migration after wounding; this effect was inhibited only by H2 antagonism. (3) When stimulated with histamine, VKC fibroblasts produced significantly more PIP than those in control media. Furthermore, VKC-derived fibroblasts were more sensitive to histamine challenge, producing significantly more PIP than normal fibroblasts. H1 and H2 antagonists did not modify histamine-stimulated PIP production. The enhanced proliferative and productive capacity of VKC fibroblasts may be the result of a selective overgrowth of one or more fibroblast subpopulations in a chronically inflamed tissue. Histamine increased proliferation, migration and collagen production in both normal and VKC fibroblasts. Since H2 antagonism modulated both cell growth and migration, but not histamine-induced collagen production, the latter may be mediated by a different receptor. These results showed that histamine is at least partially responsible for fibroblast stimulation.

Role of TGF-β1 on the IgE-Dependent Anaphylaxis Reaction

TGF-β1 is a member of a family of polypeptide factors that control proliferation, differentiation, chemotaxis, and other functions in many cell types. TGF-β1 has been shown to inhibit many immunologic functions. However, here we report that TGF-β1 has an important role in the elicitation of IgE-dependent allergic reactions. The synthetic antisense TGF-β1 oligonucleotides dose-dependently inhibit passive cutaneous anaphylaxis (PCA) reaction and histamine release from the mast cells activated by anti-DNP IgE in rats. The level of cAMP in mast cells, when antisense TGF-β1 oligonucleotides was added, significantly increased ∼7-fold compared with that of basal cells. The antisense TGF-β1 oligonucleotides also had a significant inhibitory effect on anti-DNP IgE-induced TNF-α release from mast cells. In situ hybridization analysis showed that the PCA reaction sites treated with antisense TGF-β1 oligonucleotides exhibited no detectable levels of TGF-β1 and l-histidine decarboxylase mRNA after anti-DNP IgE stimulation, whereas the PCA reaction sites treated with sense TGF-β1 oligonucleotides possessed significant amounts of their mRNA. Additionally, neutralizing Ab to TGF-β1 blocked the PCA reaction significantly, but its Ab did not inhibit peritoneal mast cell-released histamine upon treatment with anti-DNP IgE. Our results suggest that TGF-β1 is critical to the development of IgE-dependent anaphylaxis reactions.

Cutaneous mesenchymal hamartoma on the foot

We report a 16-year-old man with a cutaneous mesenchymal hamartoma on the left foot since infancy. Clinically, the lesion was 10x6 cm in size, relatively ill-defined, skin colored, and comprised of confluent nodules. Histopathologic examination revealed histology compatible with cutaneous mesenchymal hamartoma.

Immunohistochemical detection of human basophils in late-phase skin reactions

BACKGROUND

Human basophils are difficult to detect with classic histochemical stains at sites of allergic inflammation. The 2D7 anti-basophil monoclonal antibody was used to identify basophils in skin during the late-phase response to a cutaneous allergen challenge.

METHODS

The 2D7 monoclonal antibody was used on protease-digested sections of skin biopsy specimens obtained 6 and 24 hours after an allergen or buffer challenge. The skin chamber technique was used to compare buffer- and allergen-challenged sites at 6 hours, and intradermal injection of allergen was used to compare allergen-challenged sites at 6 and 24 hours.

RESULTS

Dramatic increases in the numbers of 2D7+ cells and in tissue staining by 2D7 were observed 6 hours after allergen challenge compared with buffer challenge. Histamine levels in skin chamber fluid varied with 2D7+ cell concentrations. By 24 hours, 2D7+ cells and tissue staining appeared to diminish but were still detectable in the allergen-challenged sites. Basophils localized primarily in and around blood vessels, whereas mast cells remained mostly in the superficial dermis. Mast cells were 2D7- in both the allergen- and buffer-challenged skin. Metachromatic staining of 2D7+ basophils with toluidine blue was absent in these tissue sections.

CONCLUSIONS

The 2D7 monoclonal antibody provides a more sensitive and precise marker than histochemical staining for human basophil involvement during the late-phase response to an allergen challenge. Basophil infiltration was observed at 6 hours only after allergen challenge and persisted at similar levels by 24 hours.

New treatment of idiopathic severe oligozoospermia with mast cell blocker: results of a single-blind study

OBJECTIVE

To determine whether mast cell blocker (tranilast) improves fertility and/or semen parameters in severe oligozoospermia.

DESIGN

Placebo-controlled single-blind clinical study.

SETTING

Nagoya University Hospital Andrology Clinic, Nagoya, Japan.

PATIENTS

Fifty men with sperm density < 5 x 10(6) sperm/mL, normal serum gonadotropins, and T, and a fertile partner were enrolled in this study.

INTERVENTIONS

Patients were prescribed randomly 300 mg/d tranilast or a placebo, three tablets per day, for 3 months. Semen and blood samples were collected before and after therapy. Semen parameters, serum gonadotropins, T, and PRL were evaluated before and after therapy.

RESULTS

The pregnancy rate (PR) in the mast cell blocker group was 28.6% compared with 0% in the placebo group. There was a statistical difference in the PR between groups. The mast cell blocker group had significantly higher levels of sperm density, sperm motility, and total motile sperm count. There were no differences between the mast cell blocker and placebo groups in seminal volume and normal sperm morphology.

CONCLUSIONS

The authors conclude that mast cell blocker is clinically useful for the treatment of idiopathic severe oligozoospermic men.

Collagen types I and III in giant papillae of vernal keratoconjunctivitis

AIMS

The objective of this study was to investigate alterations in conjunctival collagen and proteoglycans in the conjunctival giant papillae of patients with vernal keratoconjunctivitis (VKC).

METHODS

Tissue samples from tarsal giant papillae of seven eyes from five patients with VKC, and five tarsal conjunctival samples from five normal patients were obtained. Tissues were processed and stained with haematoxylin and eosin, Van Gieson, trichromic Mallory, toluidine blue, Alcian blue, and alkaline Giemsa. Collagen extraction was performed in acetic acid and pepsin, total collagen was quantified using hydroxy-proline levels, and collagen types I and III were analysed by gel electrophoresis (SDS-PAGE). Proteoglycans were quantified using uronic acid levels.

RESULTS

Histological evaluation showed a significant increase of mast cells in the epithelium (0/mm2 v 147/mm2, p < 0.01) and in the stroma (5.1/mm2 v 80/mm2, p < 0.01) of VKC patients. Collagen fibres were thicker and arranged irregularly, with the total amount significantly increased. Owing to an increased percentage of type III collagen, the ratio of collagen types I to III was decreased. Proteoglycans were also reduced in VKC samples.

CONCLUSION

The well known morphological abnormalities observed in VKC correspond to alterations in the ratio between collagens and proteoglycans, and between different types of collagen. The greatly increased number of mast cells found in these tissues suggests an active role for these cells in the abnormal connective tissue metabolism observed in VKC.

The role of the autonomic nervous system in chemically-induced liver damage and repair--using the essential hypertensive animal model (SHR)

The effects of autonomic nervous system on liver damage induced by carbon tetrachloride (CCl4) and repair were investigated morphologically and biochemically in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). After repetition of CCl4 treatment twice a week for 4 weeks, the SHR showed liver cirrhosis histologically. In WKY, however, only fibrosis was observed. Biochemically, the serum glutamate-pyruvate transaminase (GPT), liver lipid peroxidation (LPO) and superoxide dismutase (SOD) activities were measured. CCl4 increased the activities of GPT and LPO but decreased that of SOD in SHR more than in WKY. These findings indicate that liver damage induced by CCl4 was more severe in the sympathetic hyperactive SHR than in the normally active WKY. In induced cirrhotic liver of SHR and fibrotic liver of WKY, diffuse serotonin particles and numerous mast cells were observed in the fibrotic matrix, and some neovascular adrenergic fibers were found in these areas. These results indicate that the sympathetic nerve can exacerbate the liver damage, and both mast cells or serotonin particles and sympathetic nerve participate at some stages in the repair of liver damage.

Mast cells are essential for the full development of silica-induced pulmonary inflammation: a study with mast cell-deficient mice

Silicosis provides a good model for chronic interstitial pulmonary inflammation. In order to clarify the role of mast cells in the development of interstitial lung diseases, silica suspension was transnasally administered to mast cell-deficient mice (WBB6F1-W/Wv) and their mast cell-intact littermates (WBB6F1(-)+/+) as well as to normal mice (C57BL/6). Histologic examinations and analyses of bronchoalveolar lavage fluid (BALF) components indicated that silica instillation induces less severe lung lesions in mast cell-deficient mice than in mast cell-intact mice. BALF neutrophilia was prominent in mast cell-intact mice, but mast cell-deficient mice developed significantly milder BALF neutrophilia. An increase in the number of lung mast cells was observed in mast cell-intact mice. To further prove the involvement of mast cells, bone marrow-derived cultured mast cells from +/+ mice were adoptively transferred to mast cell-deficient mice. These mast cell-reconstituted mice developed more severe pulmonary lesions than did the mast cell-deficient mice; the severity of the lesions was similar to that in mast cell-intact mice. In addition, BALF neutrophilia was elicited by mast cell reconstitution. A significant number of mast cells was found in the lungs of mast cell-reconstituted mice when silica was administered. These results suggest the involvement of mast cells in the development of silicosis and implicate interactions between mast cells and neutrophils in the pathogenesis of this disorder.

Systemic sclerosis

Systemic sclerosis affects the connective tissue of various organs. It is characterized by alteration of the microvasculature with a dense inflammatory cellular infiltrate, followed by massive deposition of collagen. This review discusses diagnostic criteria, clinical subsets, survival data, clinical evaluation, epidemiology, pathogenesis, immunobiology, genetics, and therapy for systemic sclerosis in adults. Because the diagnosis of systemic sclerosis is most dependent on its cutaneous involvement, knowledge of this is essential in the evaluation and management of patients with this disorder.

Characterization of inflammatory infiltrates in male pattern alopecia: implications for pathogenesis

Hair-bearing, transitional, and alopecic scalp from three males and one female with progressive pattern alopecia were examined. Ultrastructural studies disclosed measurable thickening of the follicular adventitial sheaths of transitional and alopecic zones compared with those in the non-alopecic zones. This finding was associated with mast cell degranulation and fibroblast activation within the fibrous sheaths. Immunohistochemically, control biopsies were devoid of follicular inflammation (n = 3), while transitional regions consistently showed the presence of activated T-cell infiltrates about the lower portions of follicular infundibula. These infiltrates were associated with the induction of class II antigens on the endothelial linings of venules within follicular adventitia and with apparent hyperplasia of follicular dendritic cells displaying the CD1 epitope. Inflammatory cells infiltrated the region of the follicular bulge, the putative source of stem cells in cycling follicles. The data suggest that progressive fibrosis of the perifollicular sheath occurs in lesions of pattern alopecia, and may begin with T-cell infiltration of follicular stem cell epithelium. Injury to follicular stem cell epithelium and/or thickening of adventitial sheaths may impair normal pilar cycling and result in hair loss.

Temporal sequence of early alterations in rat lung following thoracic X-irradiation

The temporal patterns of several responses in the lungs of groups of rats administered two different thoracic doses of X-rays (7.5 and 15 Gy) were examined during a time frame within which radiation pneumonitis develops (1-13-week period) in order to assess for potential interrelationships among the responses. Endpoints surveyed included lung gravimetric and volumetric changes, changes in lavaged alveolar macrophage (AM) numbers, interstitial accumulations of mast cells (MC), and alterations in the amounts of lavaged phospholipids (PL), protein (P), and histamine (H). Sham-irradiated rats served as controls. Early (1 week), dose-dependent increases in lavageable PL were not accompanied by increases in lung weights or lavageable P. Elevations in lavaged PL continued for at least 5 weeks after exposure. By this time, lung weights, AM numbers, MC, and lavageable P, but not lavageable H, were all substantially increased in lungs that received the 15 Gy dose, whereas these changes were not observed at the lower dose. At later times (weeks 7 and 9), the hyperpermeability response following the 15 Gy exposure became less pronounced and the PL response also subsided, while lung MC continued to further increase and lavageable H became abnormally elevated. Maximal increases in the lung's permeability status after the 15 Gy exposure was coincidental with maximal increases in AM. An association of increases in AM and lung hyperpermeability, however, was not evident as of week 13 after the 7.5 Gy dose when lung weights and lavageable P were significantly elevated. For the X-ray doses examined, our results suggest that: (1) the early PL response to X-rays is independent of, and precedes, permeability changes in the lung; (2) the time to onset of an X-irradiation-induced increase in lung permeability is dose-dependent; (3) the progressive accumulation of MC in the lung following X-irradiation is dose-dependent; (4) excessive accumulations of interstitial MC after X-irradiation do not necessarily result in an increase in free H; and (5) free H in the lung does not appear to play a prominent role in the hyperpermeable response. Additionally, in conjunction with the findings of other investigators, our study suggests that the MC response to X-rays may be a fundamental component of the fibrogenic response.

Cutaneous mesenchymal hamartoma in the palm

A case of congenital, solitary, cutaneous mesenchymal hamartoma in the palm of the left hand is reported. The mass was composed mainly of an intimate mixture of fibrocollagenous bundles and islands of mature fat cells, distorted blood vessels with smooth muscle in the wall, and eccrine sweat glands. Many mast cells were scattered throughout the fibrocollagenous bundles. The mast cell may be an important cell in this hamartoma.

Endobronchial biopsy positive sarcoidosis: relation to bronchoalveolar lavage and course of disease

Sixty-two patients with newly diagnosed sarcoidosis were examined with fibreoptic bronchoscopy, endobronchial biopsies and bronchoalveolar lavage (BAL) were analysed. Epithelioid granulomatosis in endobronchial biopsies were found in 28 (45%) of the patients (BPOS). The patients in this BPOS group showed higher inflammatory activity in BAL fluid compared to those with negative biopsies (BNEG), with significant increases in lymphocyte and mast cell counts, and concentrations of procollagen III peptide and albumin. The patients were followed over a period of 2 years. The BPOS group tended to have a worse clinical course with more patients having a progressive disease and more patients requiring treatment with systemic steroids. We conclude that the findings of epithelioid granulomatosis in endobronchial biopsies may reflect a more intense and widespread inflammation in the lung.

Identification of IgE-positive cells and mast cells in frozen sections of multiple sclerosis brains

There is evidence that nervous system mast cells may be involved in the pathogenesis of experimental demyelinating diseases, and that their involvement may be mediated by IgE. In order to examine the possible relevance of these observations to human demyelinating diseases, we have histologically and immunocytochemically examined multiple sclerosis (MS) and control brains for the presence of mast cells and IgE. Using a highly specific antiserum, we found IgE-positive cells in MS brains, but not in controls. IgE-positive cells could be detected in all regions of MS lesions, but were far more frequent in areas of active infiltration. Immunopositive staining was only observed when sections were pretreated with a methanolic peroxide solution, suggesting that the IgE was cytoplasmic. Positive cells typically exhibited plasma cell morphology. Mast cells were identified using chloroacetate esterase (CAE) staining, and we were able to confirm previous reports of an increased association of mast cells with MS lesions. Mast cells were seen in 7/14 MS brains compared with 1/8 controls. They were most commonly observed in demyelinated areas, but were also seen in association with infiltrate. Mast cells and IgE-positive cells were also observed in areas of perivascular infiltration in other inflammatory central nervous system diseases (subacute sclerosing panencephalitis, herpes encephalitis). Mast cells may represent a route for infiltrating cells to enter the brain in inflammatory disorders.

Dermal mast cell degranulation in systemic sclerosis

Paired biopsy samples from involved and uninvolved skin were obtained from 19 patients with generalized scleroderma (11 with early, progressive disease and 8 with late, improving disease). Skin biopsy samples were double stained for mast cell granules and for mast cell membrane. The number of mast cells was increased in patients with systemic sclerosis (SSc), in both involved and uninvolved skin and in both early and late disease. There was an increase in the number of degranulated mast cells in the involved skin of patients with both early and late disease and in the not-yet-involved skin of patients with early disease; however, there was no increase in the number of degranulated mast cells in areas of previously involved but now normal skin of patients with late disease. Increases in mast cell number and degranulation precede clinically apparent dermal fibrosis in SSc. These observations and the absence of mast cell degranulation in regressing skin suggest a participatory role of the mast cell in the clinical progression of skin changes in SSc.

Mast cells and fibrosis in compartments of lymph nodes of normal, gnotobiotic, and athymic rats

Reports vary on the amount and distribution of mast cells in lymph nodes. We analysed the mast-cell population in compartments of nodes of diverse sites, from euthymic and athymic animals of various ages. Nodal mast cells were few in young animals, occurring mostly in medullary sinuses. Aging is often accompanied by a moderate increase of nodal mast cells. In compartments of a few nodes of some aged athymic and euthymic animals, the mast cells were greatly increased in the extrafollicular zone overlying medulla directly. In certain cases, this great increase was accompanied by pronounced mast-cell degranulation and by fibrosis in the mast cell-rich extrafollicular zone. It is suggested that the mast cells of medullary sinuses relate to non-immunological events, while those of the lymphoid parenchyma relate to elements that can induce humoral immune responses or are somehow involved in nodal processes of such responses. It is further suggested that an occasional emergence, with aging, of a deficiency of particular humoral immune responses may induce an excessive increase of cortical mast cells, and that activities of the resulting dense mast-cell population contribute to the onset of fibrosis.

Mast cells, nerves and fibrosis in the appendix: a morphological assessment

Mast cells are closely associated with nerves in the mucosa of the appendix vermiformis, and obliteration of the appendiceal lumen by fibrous tissue is accompanied by neurogenous hyperplasia. However, changes in the density of mast cells in this process have not been reported. Accordingly, fibrosis was graded in haematoxylin and eosin sections from 46 samples of human appendix. This was compared with mast cell number in toluidine blue-stained slides and nerve density in PGP9.5-immunoreactive sections. In the mucosa, the mast cell number in the samples with minimal fibrosis was three times greater than in those classified as normal (P less than 0.0001), and this declined in the more fibrotic samples. The mucosal nerve scores paralleled the mucosal mast cell changes, and stereological analysis revealed a correlation of mast cell number and nerve density within the lamina propria of the same specimens (r = 0.49-0.90). In the submucosa, mast cell numbers and nerve scores were not significantly different in the different histological grades and obliterated samples resembled normal submucosa, except that a dense axial block of nerve staining was often present. The progressive fibrotic changes in appendices provide a human model for studying the relationships of nerves, mast cells, and fibrosis in the gastrointestinal tract.

Histamine release from mouse and rat mast cells cultured with supernatants from chronic murine graft-vs-host splenocytes

There is growing interest in studying pathways of mast cell activation. In a mouse model of chronic graft-vs-host disease (cGVHD) extensive mast cell activation and degranulation occurs in vivo coincident with the development of dermal fibrosis. An interesting feature of this model is that the mast cell reaction is slow to develop, occurring over a period of weeks and waning by 300 days. The aim of our work was to investigate the effects of supernatants from splenocytes of such cGVHD mice (cGVHD sups) on mouse and rat peritoneal mast cells cocultured with 3T3 skin fibroblasts. We found that cGVHD sups are able to release histamine from both mouse and rat cultured mast cells in a slow fashion. Histamine release became evident only after 5-8 days of coculture of the mast cells with the cGVHD supernatants and thereafter decreased to basal levels. Mast cell activation due to cGVHD supernatants was a noncytotoxic event as demonstrated by mast cell counts in the cocultures and by the ability of mast cells to exclude trypan blue. Mast cells that had been activated by incubation with the cGVHD sups were as responsive to stimulation with either anti-IgE antibodies or compound 48/80 as were mast cells incubated with control sups. Supernatants from mice early in GVHD (Days 11-28) were most active in promoting histamine release. Supernatants from spleens of mice which had GVHD for 290 days and where the mast cells had returned to full granulation in vivo were inactive. This is the first in vitro study demonstrating slow mast cell histamine release instituted by other cells, namely the splenocytes of cGVHD mice.

A mast cell secretagogue, compound 48/80, prevents the accumulation of hyaluronan in lung tissue injured by ionizing irradiation

Irradiation with a single dose of 30 Grey on the basal regions of the lungs of Sprague-Dawley rats induced a peribronchial and alveolar inflammation. Infiltration of mast cells in the edematous alveolar interstitial tissue and also in the peribronchial tissue were characteristic features of the lesion. The appearance of mast cells was already seen 4 wk after irradiation and by weeks 6 to 8 there was a heavy infiltration. The staining properties suggested that they were connective tissue-type mast cells. The infiltration of mast cells was paralleled by an accumulation of hyaluronan (hyaluronic acid) in the alveolar interstitial tissue 6 and 8 wk after irradiation. The recovery of hyaluronan (HA) during bronchoalveolar lavage (BAL) of the lungs also increased at this time. Treatment with a mast cell secretagogue, compound 48/80, induced a distinct reduction of granulated mast cells in the alveolar tissue. Regular treatment with compound 48/80 from the time of irradiation considerably reduced the HA recovery during BAL and the HA accumulation in the interstitial tissue but did not affect the interstitial infiltration of mononuclear cells and polymorphonuclear leukocytes. By contrast, an accumulation of HA in the alveolar interstitial space was induced when compound 48/80 was given not until mast cell infiltration of the lung had started. The effects of compound 48/80 indicate that the connective tissue response after lung irradiation is dependent on whether or not mast cell degranulation is induced before or after the mast cell infiltration of the alveolar tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Exogenous electric current can reduce the formation of hypertrophic scars

Exogenous electric current has been shown to influence the healing of wounds in both human subjects and animal models. We examined the effect of positive polarity electrical stimulation on the resultant scar thickness of surgically induced wounds, and report that electrotherapy can reduce scar thickness and hypertrophic scar formation.

Challenge with gliadin induces eosinophil and mast cell activation in the jejunum of patients with celiac disease

PURPOSE

The aim of this study was to clarify the role of eosinophils and mast cells in the small bowel in celiac disease.

PATIENTS AND METHODS

Patients with celiac disease (n = 10) were investigated by perfusion of a closed jejunal segment. The concentrations of certain granule constituents from eosinophils, eosinophil cationic protein (ECP), and from mast cells/basophils, histamine, were measured and the jejunal secretion rates of these cellular markers were calculated.

RESULTS

Compared with findings in healthy control subjects (n = 14), increased secretion rates were observed under basal conditions in patients with histopathologically active celiac disease. Gliadin, administered by perfusion to the jejunal segment, induced a fourfold increase in ECP secretion and a twofold increase of histamine secretion in patients with celiac disease (n = 7), but did not influence the secretion rates of these substances in healthy controls (n = 3). The secretion rate of ECP started to increase 20 minutes after challenge of the perfused segment with gliadin and reached maximum levels 40 minutes later. The secretion rate of histamine started to increase 40 minutes after gliadin administration. Concurrently with these inflammatory events, the secretion of albumin was doubled as a sign of increased mucosal leakage.

CONCLUSION

These data indicate that eosinophils and mast cells are both involved in the early gliadin-induced reactions of the small intestine, and suggest that these cells are effector cells participating in the celiac lesion of the mucosa.

Elastic fibres in patients with systemic sclerosis. A morphological study

Dermal elastic fibres in biopsies taken from sun-exposed involved digital skin and sun-protected uninvolved skin on the medial aspect of the upper arms from 13 patients with systemic sclerosis were examined by light and transmission electron microscopy. For controls, biopsies were taken from similar sites from 4 age- and sex-matched healthy volunteers and 4 patients with primary Raynaud's phenomenon. On light microscopy only the control digital biopsies showed mild actinic changes of the elastic fibres whereas in all the biopsies from patients with systemic sclerosis identical changes of thickening, clumping and fragmentation of the elastic fibres were observed. Quantitative assessment of the dermal elastic fibres using microdensitometry and video image analysis showed no significant difference between the patients and controls. On electron microscopy more advanced abnormalities similar to those seen in actinic damage and chronological aging were found in the biopsies from all the patients with systemic sclerosis compared to the controls.

Mast cell changes in a case of rapidly progressive scleroderma-ultrastructural analysis

A 63-year-old woman had rapidly progressive scleroderma and died 4 months after the clinical appearance of her illness. Extreme itching of the affected skin was prominent. Electron microscopic study of the clinically uninvolved skin showed mainly normal mast cells. Mast cells in clinically involved skin showed a wide morphologic spectrum including evidence of cellular activation. There was an increased amount of cytoplasm occupied by polysomes and mitochondria and less cytoplasm occupied by granules. Most granules were pale and swollen, suggesting active degranulation. In some cases it was difficult to distinguish a hyperactive mast cell with only a few granules remaining from a fibroblast which had acquired granules by transgranulation. This case illustrates the active participation of mast cells in acute scleroderma.