The mast cell in health and disease

Rosacea pathogenesis and therapeutics: current treatments and a look at future targets

Rosacea is a chronic inflammatory skin condition associated with a significant health and economic burden from costs and loss of productivity due to seeking medical treatment. The disease encompasses multiple phenotypic manifestations involving a complex and multi-variate pathogenesis. Although the pathophysiology of rosacea is not completely understood, ongoing research is continually elucidating its mechanisms. In this review, current concepts of rosacea pathogenesis will be addressed which involve skin barrier and permeability dysfunction, the innate and adaptive immune systems, and the neurovascular system. More specifically, the cathelicidin pathway, transient potential receptor channels, mast cells, and the NLRP3 inflammasome pathway are various targets of current pharmacologic regimens. Future therapies may seek different mechanisms to act on current treatment targets, like the potential use of JAK/STAT inhibitors in ameliorating skin barrier dysfunction or TLR antagonists in alleviating cathelicidin mediated inflammation. Other potential treatments aim for entirely different molecular targets such as microvesicle particle mediated local and systemic inflammation. Ultimately rosacea is associated with a significant health and economic burden which warrants deeper research into its pathogenesis and resultant new treatment discovery.

Pediatric and Hereditary Mastocytosis

To a large extent, the clinical picture of pediatric mastocytosis depends on the age at which it is diagnosed. A neonate with diffuse cutaneous mastocytosis may frequently present in a severe state requiring treatment. Toddlers may require long-term anti-mediator therapy, and this may lead to concerns such as organizing preschool education due to the need for epinephrine injections. A teenager may have to face cutaneous disease persistence or a diagnosis of systemic mastocytosis. Further studies are needed to refine the available treatment options and prognosis for different age groups.

Validation of dermatopathological criteria to diagnose cutaneous lesions of mastocytosis: importance of KIT D816V mutation analysis

BACKGROUND

Cutaneous lesions of mastocytosis CLM are often subtle and may require biopsy. However, dermatohistopathological criteria for CLM remain undefined.

OBJECTIVES

To establish criteria for CLM by validating histological and molecular parameters.

METHODS

In skin samples from Caucasian patients with CLM and controls (atopic dermatitis, chronic urticaria, pruritus, tissue from tumor safety margin excisions), mast cell (MC) numbers, size, shape, distribution, immunostainability with a large panel of markers, pigmentation and presence of KIT D816V mutation were analysed.

RESULTS

Forty-seven CLM patients (32 maculopapular cutaneous mastocytosis (MPCM), 15 mastocytomas and 36 controls were included. Mastocytomas were easily identified by densely packed cuboidal MCs. In MPCM, skin MC density in CD117 stains was higher in CLM patients than in controls (p<0.0001) and values correlated closely (r=0.65, p<0.0001) to results in tryptase stains. The optimized upper dermis cut-off number of 62 MC/mm² had a sensitivity and specificity of 92% in both stainings, corresponding to approximately 12 MC/high power field (HPF). MC size was larger in MPCM than in controls (p=0.01). Interstitial (= not perivascular or periadnexal) MCs and stronger basal pigmentation of the epidermis were indicative of MPCM (p < 0.0001 each) and clusters of > 3 MC/HPF exclusively found in MCPM. Surface markers CD2, CD25 and CD30 stained T-lymphocytes, but only negligibly CLM MC. The KIT D816V mutation in formalin fixed paraffin embedded (FFPE) skin was evaluable in 87.5% of MCPM patients and had both 100% sensitivity and specificity.

CONCLUSIONS

MPCM can be predicted by major and minor criteria combined in a scoring model. Presence of D816V mutation in FFPE skin and MC density > 27/HPF are >95%-specific major criteria for MPCM. MC densities 12/HPF, interstitial MC, clusters and basal pigmentation are minor criteria.

Chlorogenic Acid Isomers Isolated from Artemisia lavandulaefolia Exhibit Anti-Rosacea Effects In Vitro

Rosacea is a chronic inflammatory disease affecting facial skin. It is associated with immune and vascular dysfunction mediated via increased expression and activity of cathelicidin and kallikrein 5 (KLK5), a serine protease of stratum corneum. Therefore, KLK5 inhibitors are considered as therapeutic agents for improving the underlying pathophysiology and clinical manifestation of rosacea. Here, we isolated the active constituents of Artemisia lavandulaefolia (A. lavandulaefolia) and investigated their inhibitory effect on KLK5 protease activity. Using bioassay-guided isolation, two bioactive compounds including chlorogenic acid isomers, 3,5-dicaffeoylquinic acid (isochlorogenic acid A) (1), and 4,5-dicaffeoylquinic acid (isochlorogenic acid C) (2) were isolated from A. lavandulaefolia. In this study, we evaluated the effects of isochlorogenic acids A and C on dysregulation of vascular and immune responses to rosacea, and elucidated their molecular mechanisms of action. The two chlorogenic acid isomers inhibit KLK5 protease activity, leading to reduced conversion of inactive cathelicidin into active LL-37. This inhibition of LL-37 production by isochlorogenic acids A and C reveals the efficacy of suppressing the expression of inflammatory mediators induced by LL-37 in immune cells such as macrophages and mast cells. In addition, both isomers of chlorogenic acid directly inhibited the proliferation and migration of vascular endothelial cells induced by LL-37.

Mast Cell Stabilizers in the Treatment of Rosacea: A Review of Existing and Emerging Therapies

Rosacea is a chronic inflammatory skin disease characterized by centrofacial erythema, papules, pustules, and telangiectasias. The onset of rosacea typically occurs after 30 years of age. It is estimated that approximately 2–5% of adults worldwide are affected. While the exact etiology of rosacea remains unknown, its pathogenesis is thought to be multifactorial with both environmental and genetic factors implicated. Ultraviolet radiation, heat, steam, ingested agents, including spicy foods and alcohol, host vasculature, dermal matrix degeneration, genetic susceptibility, and microbial organisms, including Demodex mites and Heliobacter pylori, have been implicated in the development of rosacea. Recently, mast cells (MCs) have emerged as key players in the pathogenesis of rosacea through the release of pro-inflammatory cytokines, chemokines, proteases, and antimicrobial peptides leading to cutaneous vasodilation, angiogenesis, and tissue fibrosis. Several existing and emerging topical, oral, and injectable therapeutics have been associated with improvement of rosacea symptoms based on their ability to stabilize and downregulate activated MCs. Herein, we review the data implicating MCs in the pathogenesis of rosacea and discuss interventions that may stabilize this pathway.

Tryptase as a polyfunctional component of mast cells

Mast cells are haematopoietic cells that arise from pluripotent precursors of the bone marrow. They play immunomodulatory roles in both health and disease. When appropriately activated, mast cells undergo degranulation, and preformed granule compounds are rapidly released into the surroundings. In many cases, the effects that mast cells have on various inflammatory settings are closely associated with the enzymatic characteristics of tryptase, the main granule compound of mast cells. Tryptase degranulation is often linked with the development of an immune response, allergy, inflammation, and remodelling of tissue architecture. Tryptase also represents an informative diagnostic marker of certain diseases and a prospective target for pharmacotherapy. In this review, we discuss the current knowledge about mast cell tryptase as one of the mast cell secretome proteases. The main points of the reviewed publications are highlighted with our microscopic images of mast cell tryptases visualized using immunohistochemical staining.

Mast cells and basophils in cutaneous immune responses

Mast cells and basophils share some functions in common and are generally associated with T helper 2 (Th2) immune responses, but taking basophils as surrogate cells for mast cell research or vice versa for several decades is problematic. Thus far, their in vitro functions have been well studied, but their in vivo functions remained poorly understood. New research tools for their functional analysis in vivo have revealed previously unrecognized roles for mast cells and basophils in several skin disorders. Newly developed mast cell-deficient mice provided evidence that mast cells initiate contact hypersensitivity via activating dendritic cells. In addition, studies using basophil-deficient mice have revealed that basophils were responsible for cutaneous Th2 skewing to haptens and peptide antigens but not to protein antigens. Moreover, human basophils infiltrate different skin lesions and have been implicated in the pathogenesis of skin diseases ranging from atopic dermatitis to autoimmune diseases. In this review, we will discuss the recent advances related to mast cells and basophils in human and murine cutaneous immune responses.

Immunohistochemical evaluation of mast cells and vascular endothelial proliferation in oral precancerous lesion-leukoplakia

Background:

Oral leukoplakia is the best-known precursor lesion. Although a morphologic feature of oral epithelial dysplasia is well described, less is known about the pathobiologic changes within the cells and over the cell surfaces for malignant transformation.

Aims:

The present study is aimed at comparing and correlating the mast cell density (MCD) and micro vascular density (MVD) in Normal Mucosa (NM) and different grades of dysplasia and to analyze their role in disease progression.

Materials and Methods:

MCD was assessed using anti mast cell tryptase and MVD was assessed immunohistochemically using anti-Factor VIII related von Willibrand factor.

Results:

The Results of the present study showed an exponential increase in microvessel density as mast cell density increased.

Conclusion:

The role of mast cells in angiogenesis as it progresses from normal mucosa to dysplasia is in concordance with the study. The number of mast cells and microvessel can be used as indictors of disease progression.

Saucerneol D inhibits eicosanoid generation and degranulation through suppression of Syk kinase in mast cells

Previously we reported that saucerneol D (SD), a naturally occurring sesquilignan isolated from Saururus chinensis (S. chinensis) suppressed lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 cells. The aim of this study was to elucidate whether SD modulates the generation of other inflammatory mediators in activated mast cells. We investigated the effects of SD on cyclooxygenase-2 (COX-2)-dependent prostaglandin D(2) (PGD(2)) and 5-lipoxygenase (5-LO)-dependent leukotriene C(4) (LTC(4)) generations as well as degranulation in cytokine-stimulated mouse bone marrow-derived mast cells (BMMCs). Biochemical analyses of the cytokine-mediated signaling pathways showed that SD suppressed the phosphorylation of Syk kinase and multiple downstream signaling processes including phospholipase Cγ1 (PLCγ1)-mediated intracellular Ca(2+) influx and activation of mitogen-activated protein kinases (MAPKs; including extracellular signal-regulated kinase 1/2 (ERK1/2), c-Jun NH(2)-terminal kinase (JNK) and p38) and the nuclear factor-κB (NF-κB) pathway. Taken together, the present study suggests that SD suppresses eicosanoid generation and degranulation through Syk-dependent pathway in BMMCs.

The possible role of trauma in skin tags through the release of mast cell mediators

Background:

Skin tags (ST) are common benign tumors of the skin but their etiopathogenesis is not well understood. STs arise in sites subjected to trauma. It was proved that mast cells are recruited to sites of skin trauma and increase their tumor necrosis factor-α (TNF-α) content.

Aim:

STs are linked to obesity and frictional sites, but this has not been studied at the molecular level. We hypothesized that mast cells, TNF-α and its family member, TNF-related apoptosis-inducing ligand (TRAIL) might play a role in the pathogenesis of STs as a response to trauma.

Materials and Methods:

A study was done on 15 patients with STs. Two STs and a snip of normal skin were obtained in each subject. We counted the mast cells after Toluidine blue staining. Enzyme-linked immunosorbant assay was used to measure TNF-α level while reverse transcriptase polymerase chain reaction was used to evaluate the level of TRAIL mRNA expression.

Results:

Mast cell count in all STs was significantly higher than that in control (P=0.0355). There was a highly significant increase in the level of TNF-α in all STs as compared to its level in controls (P<0.0001). Expression of TRAIL mRNA was significantly higher in STs as compared to its expression in controls (P<0.0001).

Conclusion:

Our study suggests that mast cells, TNF-α and TRAIL may play a role in the pathogenesis of STs.

Catestatin, a neuroendocrine antimicrobial peptide, induces human mast cell migration, degranulation and production of cytokines and chemokines

Catestatin, a neuroendocrine peptide with effects on human autonomic function, has recently been found to be a cutaneous antimicrobial peptide. Human catestatin exhibits three single nucleotide polymorphisms: Gly364Ser, Pro370Leu and Arg374Gln. Given reports indicating that antimicrobial peptides and neuropeptides induce mast cell activation, we postulated that catestatin might stimulate numerous functions of human mast cells, thereby participating in the regulation of skin inflammatory responses. Catestatin and its naturally occurring variants caused the human mast cell line LAD2 and peripheral blood-derived mast cells to migrate, degranulate and release leukotriene C(4) and prostaglandins D(2) and E(2). Moreover, catestatins increased intracellular Ca(2+) mobilization in mast cells, and induced the production of pro-inflammatory cytokines/chemokines such as granulocyte-macrophage colony-stimulating factor, monocyte chemotactic protein-1/CCL2, macrophage inflammatory protein-1α/CCL3 and macrophage inflammatory protein-1β/CCL4. Our evaluation of possible cellular mechanisms suggested that G-proteins, phospholipase C and the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) are involved in catestatin-induced mast cell activation as evidenced by the inhibitory effects of pertussis toxin (G-protein inhibitor), U-73122 (phospholipase C inhibitor) and U0126 (ERK inhibitor), respectively. We also found that human mast cells express the α7 subunit of the nicotinic acetylcholine receptor at both the mRNA and protein levels. Given that silencing the α7 receptor mRNA and an α7-specific inhibitor did not affect catestatin-mediated activation of mast cells, however, we concluded that this receptor is not likely to be functional in human mast cell stimulation by catestatins. Our finding that the neuroendocrine antimicrobial peptide catestatin activates human mast cells suggests that this peptide might have immunomodulatory functions, and provides a new link between neuroendocrine and cutaneous immune systems.

Increased angiogenesis and mast cells in the centre compared to the periphery of vitiligo lesions

The larger number of T-lymphocytes in the periphery of vitiligo lesions and their association with angiogenesis are reported. The objective of this study was to investigate angiogenesis, VEGF and mast cell in vitiligo lesions. Specimens of 30 patients' biopsies, from lesional and perilesional nondepigmented skin were stained for mast cells, CD34 and VEGF. The evaluation was made by image analysis and the measured variables were statistically analyzed. A significantly increased number of CD34 and VEGF positive vessels and mast cells were detected in the centre of the lesion than in the periphery (p < 0.0001, p < 0.0001 and p = 0.001). There was a positive correlation of CD34, VEGF and mast cell number between the centre and the periphery of the lesions (r = 0.877, p < 0.0001; r = 0.946, p < 0.0001 and r = 0.863, p < 0.0001, respectively). The increased angiogenesis and mast cell numbers in the area where lymphocyte number is lower may be explained with the stepwise inflammatory process in vitiligo.

IL-6, but not IL-4, stimulates chemokinesis and TNF stimulates chemotaxis of tissue mast cells: involvement of both mitogen-activated protein kinases and phosphatidylinositol 3-kinase signalling pathways

An increase in the number of mast cells within tissues is observed in many pathophysiological conditions. Current data indicate that migration of mature mast cells might be one of the key mechanisms responsible for rapid local accumulation of these cells. Considering that interleukin (IL)-6 and IL-4, as well as tumour necrosis factor (TNF), influence mast cell activity in various ways, the purpose of the current study was to examine whether these cytokines function as rat peritoneal mast cell chemoattractants. We showed that IL-4, in the concentration range from 10(-6) to 10(-3) ng/ml, did not induce a mast cell migratory response, even in the presence of laminin and fibronectin. Under the same experimental conditions, mast cells were shown to migrate in response to IL-6 stimulation in the presence of laminin. The optimal concentration of IL-6 for maximal migration of mast cells was 10(-4) ng/ml (i.e. approximately 5 nM). In comparison, the optimal concentration of TNF for maximal migration of mast cells was 5 x 10(-5) ng/ml (i.e. approximately 3 fM). IL-6-stimulated mast cell migration was the result of chemokinesis, whereas TNF-induced migration was the result of chemotaxis. Mast cell migratory responses to IL-6 and TNF were entirely blocked by specific anti-IL-6R and anti-TNFR1 antibodies. We also documented that the migration response of mast cells to stimulation with IL-6 and TNF was mediated through signal transduction pathways involving mitogen-activated protein kinases and phosphatidylinositol 3-kinase. Taken together, our results indicate that IL-6, as well as TNF, induces tissue mast cell migration. Thus, these proinflammatory cytokines can be responsible for mast cell accumulation at the site of diverse conditions accompanied by inflammation.

A study of the pathogenesis of rosacea: how angiogenesis and mast cells may participate in a complex multifactorial process

In the present study we evaluated, in involved and clinically uninvolved skin of Rosacea, microvessels density (MVD) and total vascular area (TVA) in addition to multiple morphologic characteristics of microvessels and also mast cells (MCs) number. We examined also the relationship between angiogenesis, MCs number and disease clinicopathological data. The study included 69 patients with Rosacea. A skin biopsy with a 4-mm punch was performed from clinically involved skin in each case. In nine randomly selected patients, facial biopsy specimens were obtained from both involved and clinically uninvolved skin. Histological sections, immunostained for factor VIII, were evaluated by image analysis for the quantification of MVD, TVA and several morphometric parameters related to the vessel size or shape. MCs detection in the dermis was carried out using the chloracetate esterase method (Fast Blue RR) in parafin sections. Serum antibodies against H.pylori were detected. Statistically important differences concerning the factors of angiogenesis between lesional and clinically non-lesional skin were demonstrated. A statistical important correlation was found also between high vascular density, PPR clinical type and the presence of ocular manifestations. MVD or TVA showed no correlation with the degree of solar elastosis or inflammation and with the Demodex density as well. However, high MVD values were found to correlate with granuloma formation in the dermis. MCs number were significantly greater in lesional compared to clinically non-lesional skin. Statistical significance was shown between MCs density and disease duration. However, no correlation between MCs number and blood vessel density was found. Angiogenesis seems to play an important role in the pathogenesis especially of the more severe clinical form of Rosacea. MCs seem to participate in evolution to disease chronicity by contributing to inflammation, angiogenesis and tissue fibrosis.

Silver-stained organizer regions and immunoglobulins in cutaneous keratoacanthomas and squamous cell carcinomas

The aim of this study was to investigate the biologic activity of epidermal cells in keratoacanthomas (KAs) and squamous cell carcinomas (SCCs) by counting the number of silver-stained nucleolar organizer regions (AgNORs), to estimate the quantity of Ig-producing cells and the inflammatory cellular infiltrate (ICI), and to make a comparative evaluation. Thirty KAs (10 at growth stage, 10 at mature stage, and 10 at involution stage) and 28 SCCs (nine well differentiated-Grade 1 (G1), seven moderately differentiated-Grade 2 (G2), five poorly differentiated-Grade 3 (G3), and seven pseudoadenoid) were investigated. The KAs examined had a mean number of 1.727 AgNORs (S.D. 0.232), and IgG predominated in most cases. IgG and IgE increase at the involution, IgA remains at almost the same level, and IgM decreases during the maturity stage. The SCCs examined had a mean number of 2.105 AgNORs (S.D. 0.446). IgG predominated and gradually increased in proportion to the degree of malignancy. There is a significant difference in the number of AgNORs and the proportion of Ig subclasses in contrast to the cellular infiltrate among the three stages of KA. In SCCs, the number of AgNORs and the percentage of Igs and ICI increased gradually in proportion to the degree of malignancy.

Antimicrobial peptides human beta-defensin (hBD)-3 and hBD-4 activate mast cells and increase skin vascular permeability

Antimicrobial peptides human beta-defensins (hBD) are mainly produced by epithelia of several organs including skin, and participate in innate immunity by killing invading pathogens. Besides their microbicidal activities, hBD activate several inflammatory and immune cells. Since hBD are generated by tissues where mast cells are present, we hypothesized that these peptides could activate mast cells. In this study, we demonstrated that both hBD-3 and hBD-4 induced mast cell degranulation, prostaglandin D2 production, intracellular Ca2+ mobilization and chemotaxis. Furthermore, hBD-3- and hBD-4-induced activation of mast cells was suppressed by pertussis toxin and U-73122, inhibitors for G protein and phospholipase C, respectively. We further revealed that hBD-3 and hBD-4 increased vascular permeability in the skin, which was dependent on the presence of mast cells, because hBD-3 and hBD-4 failed to enhance vascular permeability in mast cell-deficient Ws/Ws rats. We also demonstrated that hBD-3 and hBD-4 induced phosphorylation of MAPK p38 and ERK1/2, which were further required for hBD-mediated mast cell activation, as evidenced by the inhibitory effects of p38 and ERK1/2 inhibitors on mast cell degranulation. Together, these findings suggest the key role of hBD in inflammatory responses by recruiting and activating mast cells, and increasing vascular permeability.

The regulatory effect of SC-236 (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-l]benzenesulfonamide) on stem cell factor induced migration of mast cells

SC-236, (4-[5-(4-chlorophenyl)-3-(trifluoromethyl)-1-pyrazol-1-]benzenesulfonamide; C(16)H(11)ClF(3)N(3)O(2)S), is a highly selective cyclooxygenase (COX)-2 inhibitor. Recently, there have been reports that SC-236 protects against cartilage damage in addition to reducing inflammation and pain in osteoarthritis. However, the mechanism involved in the inflammatory allergic reaction has not been examined. Mast cells accumulation can be related to inflammatory conditions, including allergic rhinitis, asthma, and rheumatoid arthritis. The aim of the present study is to investigate the effects of SC-236 on stem cell factor (SCF)-induced migration, morphological alteration, and cytokine production of rat peritoneal mast cells (RPMCs). We observed that SCF significantly induced the migration and morphological alteration. The ability of SCF to enhance migration and morphological alteration was abolished by treatment with SC-236. In addition, production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and vascular endothelial growth factor (VEGF) production induced by SCF was significantly inhibited by treatment with SC-236. Previous work has demonstrated that SCF-induced migration and cytokine production of mast cells require p38 MAPK activation. We also showed that SC-236 suppresses the SCF-induced p38 MAPK activation in RPMCs. These data suggest that SC-236 inhibits migration and cytokine production through suppression of p38 MAPK activation. These results provided new insight into the pharmacological actions of SC-236 and its potential therapeutic role in the treatment of inflammatory allergic diseases.

The CD200 receptor is a novel and potent regulator of murine and human mast cell function

CD200R is a member of the Ig supergene family that is primarily expressed on myeloid cells. Recent in vivo studies have suggested that CD200R is an inhibitory receptor capable of regulating the activation threshold of inflammatory immune responses. Here we provide definitive evidence that CD200R is expressed on mouse and human mast cells and that engagement of CD200R by agonist Abs or ligand results in a potent inhibition of mast cell degranulation and cytokine secretion responses. CD200R-mediated inhibition of FcepsilonRI activation was observed both in vitro and in vivo and did not require the coligation of CD200R to FcepsilonRI. Unlike the majority of myeloid inhibitory receptors, CD200R does not contain a phosphatase recruiting inhibitory motif (ITIM); therefore, we conclude that CD200R represents a novel and potent inhibitory receptor that can be targeted in vivo to regulate mast cell-dependent pathologies.

Role of mast cells in the development of renal fibrosis: use of mast cell-deficient rats

BACKGROUND

Recent clinical studies have shown that the number of interstitial mast cells increases in various types of renal disease and correlates well with the magnitude of interstitial fibrosis. The present study was conducted to assess the role of mast cells in renal fibrosis by examining an experimental glomerular disease.

METHODS

A rat model of chronic glomerular disease, puromycin aminonucleoside-nephrosis, was induced in mast cell-deficient (Ws/Ws) and normal (+/+) rats.

RESULTS

The area of interstitial fibrosis was widely distributed at 6 weeks in both groups of rats; however, unexpectedly, the area of interstitial fibrosis was greater in Ws/Ws rats than in +/+ littermates. Biochemical analysis of the hydroxyproline content confirmed the more severe fibrosis in the Ws/Ws rats. The number of mast cells increased in both Ws/Ws and +/+ rats, concomitant with the development of interstitial fibrosis, but was confirmed to be lower in Ws/Ws than in +/+ rats. There were no differences in the numbers of interstitial macrophages and T lymphocytes between the two groups. Reverse transcription-polymerase chain reaction analysis of cytokine expression revealed that the level of mRNA for transforming growth factor-beta (TGF-beta), a potent profibrotic cytokine, was higher in Ws/Ws rats. In addition, heparin, one of the major components of mast cells, inhibited the expression of TGF-beta mRNA in rat fibroblasts in culture.

CONCLUSION

These results suggest that mast cells do not play a major role in the pathogenesis of interstitial fibrosis in puromycin aminonucleoside nephrosis. Rather, they might be protective or ameliorative in this model through the inhibition of TGF-beta production by heparin, and possibly in other models and also in humans.

Regulatory Effects of Cytokine Production in Atopic Allergic Reaction by Gammi-Danguieumja

Gammi-danguieumja (GD) is clinically used in South Korea for treating atopic dermatitis. However, its effects in experimental models remain unknown. We investigated a possible effect of GD on cytokines production using human T cell line (MOLT-4) or human mast cell line. As a result, GD (0.01 mg/mL)-containing medium in stimulated culture supernatants increased IL-2 and IFN-gamma, and decreased IL-4 secretion in MOLT-4. GD (0.01-1 mg/mL)-containing medium in stimulated culture supernatants dose-dependently and significantly decreased IL-8, IL-13, and tumor necrosis factor-alpha secretion on the phorbol 12-myristate 13-acetate and A23187-stimulated HMC-1. In addition, GD inhibited histamine release from activated mast cells. These results suggest that GD contributes to the regulation of atopic allergic reactions.

Mast cells: an unexpected finding in the modulation of cutaneous wound repair by charged beads

Increased numbers of mast cells are affiliated with a broad spectrum of pathologic skin conditions, including ulcers, atopic dermatitis, neurofibromatosis, hemangiomas, keloids, and hypertrophic scars. It has been proposed that mast cells play a primary pathophysiologic role in these disorders and that their presence represents not merely a secondary event. While investigating their recent hypothesis that positively charged cross-linked diethylaminoethyl dextran (CLDD) beads potentiate cutaneous wound healing, the authors serendipitously observed increased numbers of mast cells in the deep dermis of wounds treated with CLDD beads. The authors propose that mast cells may play an important role in the modulation of healing seen with CLDD beads. Incisional wounds were studied in 30 Sprague-Dawley rats partitioned into two groups that were killed 7 or 14 days after wounding. The wounds were treated with positively, negatively, or neutrally charged CLDD beads. Physiologic saline served as a control. At the designated times after incisional wounding, biopsy specimens were tested for wound breaking strength or processed for histologic testing, fixed in 4% paraformaldehyde, and stained with Giemsa and Goldner-Masson trichrome. Mast cells were counted under light microscopy in a blinded fashion and were expressed as the number of cells per millimeter squared. Significant increases in the number of mast cells were observed in the deep dermis of incisional wounds after implantation with positively or negatively charged CLDD beads. In contrast, neutrally charged beads had no effect on mast cell numbers. At 7 days, the incisions treated with positively charged beads averaged 2.1 times more mast cells compared with those treated with physiologic saline or neutrally charged beads, whereas the incisions treated with negatively charged beads displayed 3.2 times more mast cells. By day 14, the incisions treated with positively charged beads averaged 2.5 times more mast cells than those wounds treated with saline or neutrally charged beads; the incisions treated with negatively charged CLDD beads had 3.4 times more mast cells. The 7-day tensiometric data indicated that wounds treated with negatively charged CLDD beads had increased breaking strength compared with wounds treated with neutrally charged beads or saline (1.8 and 1.7 times, respectively; p = 0.01 and p = 0.02). Wounds treated with positively charged beads also showed increased breaking strength compared with wounds treated with neutrally charged beads or saline (1.5 and 1.4 times greater); however, this did not reach statistical significance. There was no apparent difference in breaking strength when neutrally charged beads were compared with those treated with saline. At 14 days, there was no statistically significant difference in wound breaking strength between different treatments. These findings are clinically germane to the assessment of proposed therapeutic applications of CLDD beads for a variety of impaired wound-healing states. Furthermore, if increased mast cell populations are intimately linked to hypertrophic scar and keloid formation, the results of the authors' study suggest that CLDD bead therapy of cutaneous wounds may lead to pathologic wound healing in humans.

A cathelicidin family of human antibacterial peptide LL-37 induces mast cell chemotaxis

The mast cell is one of the major effector cells in inflammatory reactions and can be found in most tissues throughout the body. During inflammation, an increase in the number of mast cells in the local milieu occurs, and such accumulation requires directed migration of this cell population. As it has previously been reported that the human cathelicidin-derived antibacterial peptide, LL-37, stimulates the degranulation of mast cells, we hypothesized that LL-37 could be a mast cell chemotaxin. The present study shows that LL-37 is a potent chemotactic factor for mast cells. The chemotactic response was dose-dependent and bell-shaped, reaching an optimal concentration of 5 microg/ml. In addition, checkerboard analysis showed that cell migration towards this peptide was chemotactic rather than chemokinetic. Moreover, Scatchard analysis using 125I-labelled LL-37-derived peptide revealed that LL-37 has at least two classes of receptors, namely high- and low-affinity receptors, on mast cells. Furthermore, the competitive binding assay suggested that LL-37 is unlikely to utilize formyl peptide receptor-like 1 (FPRL1), a functional LL-37 receptor for neutrophil and monocyte migration, on mast cells. In addition, the treatment of cells with pertussis toxin and phospholipase C inhibitor, U-73122, inhibited LL-37-mediated migration, indicating that LL-37 induces mast cell chemotaxis through a Gi protein-phospholipase C signalling pathway. These results show that besides its antibacterial activities, LL-37 may have the potential to recruit mast cells to inflammation foci.

Epithelial cell-derived human beta-defensin-2 acts as a chemotaxin for mast cells through a pertussis toxin-sensitive and phospholipase C-dependent pathway

Mast cells are known to accumulate at the sites of inflammation in response to chemoattractants generated in the local milieu. Since human beta-defensin-2 (hBD-2) is generated in several epithelial tissues where mast cells are present and because we have recently reported that this human antibacterial peptide induces mast cell degranulation, we thus hypothesized that hBD-2 could be a mast cell chemotaxin. Here we report that hBD-2 directly and specifically induces mast cell migration with an optimal concentration of 3 microg/ml. Checkerboard analysis showed that the migration was more chemotactic rather than chemokinetic. Moreover, Scatchard analysis using 125I-labeled hBD-2 revealed that mast cells have at least two classes of receptors, high- and low-affinity receptors, for this peptide. Moreover, the competitive binding assay suggested that hBD-2 is unlikely to utilize CCR6, a functional receptor for hBD-2-mediated dendritic and T cell migration, on mast cells. In addition, treatment of mast cells with G protein inhibitor, pertussis toxin, and phospholipase C inhibitor, U-73122, abolished the cell chemotaxis in response to hBD-2, indicating that the G protein-phospholipase C signaling pathway is involved in hBD-2-induced mast cell activation. Thus, we suggest that hBD-2, which was originally believed to be involved in innate host defense, may participate in the recruitment of mast cells to inflammation foci.

Mast cell density and IL-8 expression in nonlesional and lesional psoriatic skin

BACKGROUND

An important cellular aberration at sites of psoriatic inflammation is an increase in the number of dermal mast cells. Being multifactorial immune effector cells, it is believed that mast cells play an essential role in perpetuating the inflammatory process of psoriasis. However, factors responsible for the infiltration and accumulation of mast cells in psoriatic lesions are largely unknown. Recent studies have demonstrated that Interleukin-8 (IL-8) exerts strong chemotactic effects on mast cells in vitro. Overexpression of IL-8 has also been reported in psoriatic lesions. In this study, we have found a correlation between the expression of IL-8 and dermal mast cell density in lesional psoriatic skin as compared to nonlesional psoriatic skin.

METHODS

Four-mm punch biopsies were taken from 14 psoriatic patients and eight healthy volunteers. Using immunohistochemical techniques, 8 microm sections of lesional psoriatic, nonlesional psoriatic, and normal control samples were evaluated for dermal mast cell density and the density of IL-8 expressing keratinocytes.

RESULTS

It was found that dermal mast cell density in lesional psoriatic, nonlesional psoriatic, and normal skin was 105.4 +/- 71.2, 42.3 +/- 30.1, and 47.5 +/- 32.5 mast cells/mm(2), respectively. IL-8+ keratinocyte density in lesional psoriatic, non lesional psoriatic, and normal skin was 171.5 +/- 67.1, 25.4 +/- 14.9 and 20.6 +/- 8.7 IL-8+ Keratinocytes/mm(2), respectively.

CONCLUSIONS

The results of this study suggest that increased levels of IL-8 in the keratinocytes of psoriatic plaques play a contributing role in the migration of mast cells to lesion sites.

Calcifying fibrous pseudotumor versus inflammatory myofibroblastic tumor: a histological and immunohistochemical comparison

Calcifying fibrous pseudotumor (CFP), a recently described lesion, is characterized by a predominantly lymphoplasmacytic infiltrate with abundant hyalinized collagen and psammomatous or dystrophic calcifications. The cause and pathogenesis are unclear, but it has been postulated that CFP may represent a sclerosing end stage of inflammatory myofibroblastic tumor (IMT). We compared the histological and immunohistochemical profiles of seven cases diagnosed as CFP and seven as IMT. Histologically, the CFP demonstrated varying degrees of calcifications in addition to fibroblastic proliferation admixed with inflammatory cells composed of lymphocytes, eosinophils, and mast cells. The IMTs rarely contain calcifications and had a myofibroblastic proliferation varying from hyalinized acellular collagen to florid fibroblastic proliferations simulating sarcoma. The inflammatory component was composed primarily of plasma cells and lymphocytes, sometimes arranged as lymphoid aggregates with germinal centers. All CFP cases were diffusely positive for factor XIIIa and negative for smooth muscle actin, muscle-specific actin, and CD34. All IMTs demonstrated diffuse positivity for actin, variable positivity for CD34, and focal positivity for Factor XIIIa. This study demonstrates certain distinct histologic, immunohistochemical, and electron microscopic features between IMTs and CFPs.

Serum levels of soluble stem cell factor and soluble KIT are elevated in patients with atopic dermatitis and correlate with the disease severity

BACKGROUND

Mast cell infiltration in skin lesions of atopic dermatitis (AD) is considered to play an important role in the pathogenesis of the disease. The most common factor that stimulates mast cell growth, migration and differentiation is stem cell factor (SCF), and the interaction of SCF and its receptor, KIT (tyrosine kinase transmembrane receptor), appears to be the key event in the recruitment and proliferation of mast cells.

OBJECTIVES

To determine whether any altered metabolism of SCF and/or KIT is present in patients with AD.

METHODS

We measured serum levels of soluble SCF (sSCF) and soluble KIT (sKIT) using enzyme-linked immunosorbent assay in 54 patients with AD, five patients with erythrodermic psoriasis vulgaris and 64 healthy individuals.

RESULTS

Serum levels of both peptides in AD patients were significantly higher than those in healthy individuals, whereas patients with psoriasis vulgaris did not show any difference from healthy controls. Both sSCF and sKIT levels were positively correlated with the disease severity in AD patients, and decreased after effective treatment with topical corticosteroids. Conclusion Serum levels of sSCF and sKIT may be useful indicators for evaluation of the activity and severity of AD.

Role of stem cell factor and monocyte chemoattractant protein-1 in the interaction between fibroblasts and mast cells in fibrosis

Mast cell infiltration and accumulation is known to occur in tissue fibrosis. Increased numbers of mast cells are detected in scleroderma or hypertrophic scar skin, however, neither the role of mast cells nor the interaction of fibroblasts and mast cells in fibrosis are fully understood. A growing body of evidence indicate that mast cells are rich source of cytokines, growth factors or chemokines, which are suggested to play an important role in the induction of fibrosis. Recent in vivo and in vitro studies suggest the involvement of monocyte chemoattractant protein-1 (MCP-1), a member of the C-C chemokine family, in fibrosis. Here, we examined the effect of stem cell factor (SCF), a mast cell growth factor, on MCP-1 gene expression in a human mast cell line, HMC-1, and as well as the effect of MCP-1 on alpha1(I) collagen gene expression in human skin fibroblasts. HMC-1 cells spontaneously expressed MCP-1 mRNA transcripts, which was detectable by in situ hybridization and Northern blot analysis. Stimulation with SCF further upregulated MCP-1 mRNA expression in a time- and dose-dependent manner, and stimulation with 100 ng/ml SCF for 24 h induced a 3-fold increase of MCP-1 mRNA expression in HMC-1 cells as compared with unstimulated cells. The concentration of MCP-1 protein in the culture supernatants of 50 ng/ml SCF-stimulated HMC-1 cells (3816+/-70 pg/ml) was significantly elevated compared to unstimulated cells (2588+/-130 pg/ml) (P < 0.01), as assessed by ELISA. Adversely, MCP-1 induced alpha1(I) collagen mRNA expression in normal skin fibroblasts dose-dependently. Finally, comparative study revealed that the concentration of SCF in the culture supernatants of scleroderma fibroblasts at primary passages was significantly increased (344.6+/-182.4 pg/ml), as compared with normal skin fibroblasts (72.4+/-20.2 pg/ml) (P<0.05). These results suggest that fibroblast-derived SCF upregulates MCP-1 expression and synthesis in mast cells, which acts on fibroblasts to enhance alpha1(I) collagen mRNA expression. Our data may indicate an important interaction of fibroblasts and mast cells, via SCF and MCP-1, in the induction of fibrosis.

Clinical and histological evaluation of an analogue of palmitoylethanolamide, PLR 120 (comicronized Palmidrol INN) in cats with eosinophilic granuloma and eosinophilic plaque: a pilot study

Fifteen cats with eosinophilic granuloma or eosinophilic plaque were given PLR 120 at the dosage of 10 mg kg-1 twice daily for one month. PLR-120 down-modulates mast cell degranulation via a receptor-mediated mechanism. No other drugs were permitted and cats were kept free of parasites throughout the study. A clinical evaluation and skin biopsies were performed before and after the treatment. Clinical improvement was assessed at 15 and 30 days. Mast cell numbers were counted and their granular content was assessed by densitometric analysis on toluidine blue-stained sections before and after the treatment. Ten of 15 (67%) cats showed clinical improvement of signs and lesions. There was no significant difference between mast cell numbers in skin biopsies taken before and after the trial, whereas the number of granules was significantly increased (P < 0.009). This pilot study suggests that PLR-120 might be a useful drug for the treatment of eosinophilic granuloma and eosinophilic plaque.

Structural diversity of mast cell granules in black and white skin

BACKGROUND

There are conflicting reports of structural differences between black and white skin, other than pigmentary differences.

OBJECTIVES

To evaluate differences in mast cells between black and white skin.

METHODS

Biopsies of normal buttock skin were obtained from four African-American males (29.2 +/- 3.0 years old) and four Caucasian males (29.4 +/- 1.2 years old) and processed routinely for electron microscopy. For the quantitative assessment of mast cell granules, five electron micrographs at a final magnification of x 53,700 were analysed for each individual, using a computer-assisted image analyser. More than 10 granules per cell, and a total of 1210 granules, were evaluated for their internal structures.

RESULTS

Mast cells in black skin contained larger granules than those in white skin (P < 0.0001). In black skin, fusion of granules seemed to account for the larger sizes. The percentage of granule matrix occupied by curved lamellae was higher in white skin, whereas parallel-linear striations were more frequent in black skin (P < 0.05). The subgranular distribution of the mast cell proteases, tryptase and cathepsin G, were evaluated by immunoelectron microscopy. Tryptase reactivity was localized preferentially over the parallel-linear striations and partially over the dark amorphous subregions within granules of black skin, whereas it was confined to the peripheral area of granules, including curved lamellae, in white skin. Cathepsin G reactivity was more intense over the electron-dense amorphous areas in both groups, while parallel-linear striations in black skin and curved lamellae in white skin were negative.

CONCLUSIONS

This study has confirmed ultrastructural differences in mast cell granules between black and white skin, which may be of functional importance.

Mast cells control neutrophil recruitment during T cell-mediated delayed-type hypersensitivity reactions through tumor necrosis factor and macrophage inflammatory protein 2

Polymorphonuclear leukocytes (PMNs) characterize the pathology of T cell-mediated autoimmune diseases and delayed-type hypersensitivity reactions (DTHRs) in the skin, joints, and gut, but are absent in T cell-mediated autoimmune diseases of the brain or pancreas. All of these reactions are mediated by interferon gamma-producing type 1 T cells and produce a similar pattern of cytokines. Thus, the cells and mediators responsible for the PMN recruitment into skin, joints, or gut during DTHRs remain unknown. Analyzing hapten-induced DTHRs of the skin, we found that mast cells determine the T cell-dependent PMN recruitment through two mediators, tumor necrosis factor (TNF) and the CXC chemokine macrophage inflammatory protein 2 (MIP-2), the functional analogue of human interleukin 8. Extractable MIP-2 protein was abundant during DTHRs in and around mast cells of wild-type (WT) mice but absent in mast cell-deficient WBB6F(1)-Kit(W)/Kit(W-)(v) (Kit(W)/Kit(W)(-v)) mice. T cell-dependent PMN recruitment was reduced >60% by anti-MIP-2 antibodies and >80% in mast cell-deficient Kit(W)/Kit(W)(-v) mice. Mast cells from WT mice efficiently restored DTHRs and MIP-2-dependent PMN recruitment in Kit(W)/Kit(W)-(v) mice, whereas mast cells from TNF(-/)- mice did not. Thus, mast cell-derived TNF and MIP-2 ultimately determine the pattern of infiltrating cells during T cell-mediated DTHRs.

Cytochemistry of mast cells: new fluorescent methods selective for sulfated glycosaminoglycans

The development and application of simple and selective fluorescent methods for routine detection of mast cells are of considerable interest because these cells play an important role in health and disease. In the present study, aspects of staining of sulfated glycosaminoglycans with carbocyanines, aryloxazoles, and a ruthenium(II) complex are discussed. The most suitable of these compounds for visualizing mast cells in smears and tissue sections are DiOC1 (3), Q-dmPOPOP, PyPO, and Rubipy, which have been practically overlooked as cationic fluorochromes for fixed cells. Bicolour fluorescence allowing simultaneous observation of mast cells and other cell types and tissue components by application of these dyes in combination with haematoxylin and/or eosin, or by counterstaining with other fluorochromes or fluorescent complexes is particularly useful for routine histopathological studies. Simple and reliable staining procedures, bright emission, high sensitivity and stability, permanent mounting, and possibilities for combined use with other histochemical methods are the most relevant advantages of these mast cell fluorochromes.

Mast cells in leprosy and leprosy reaction

BACKGROUND

Mast cells can be visualized in routine, acid-fast-staining, paraffin tissue section as metachromatic staining cells, and can be activated to release inflammatory mediators which play a role in the cell-mediated immune response.

METHODS

Skin biopsy tissues were taken from the most active skin lesion of each leprosy patient at the time of diagnosis (nonreactional group) and at the time of reaction (reactional group) during the years 1994-1997 in the leprosy clinic at the Department of Dermatology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Thailand. Mast cells were identified by metachromatic staining (purple) in Fite's stain sections and reported as the average number of cells per high power field in three compartments: at the center and periphery of the granuloma and in the interstitium. The data were analyzed in three groups: nonreactional group, type I, and type II leprosy reactions. The mast cell count of each group and each compartment of the section, expressed as the mean +/- standard error, was compared.

RESULTS

A total of 95 persons were included in the study, but 108 tissue sections were obtained due to nine cases having more than one section. Of these patients, 63 cases (66.32%) had no reaction, 19 cases (20%) had type I reaction, and 13 cases had type II reaction. There was no difference in age and sex among these groups. The mast cell count in the interstitium was higher than that within the granuloma, both at the center and at the periphery, in every type, and the count in this area reduced significantly in leprosy reactions, both type I and type II, compared with the nonreactional group.

CONCLUSIONS

The change in the average mast cell number in nonreactional leprosy and leprosy reactions may indicate the important role of mast cells in dynamic changes in the cell-mediated immune response in leprosy and leprosy reactions.

Nerve growth factor functions as a chemoattractant for mast cells through both mitogen-activated protein kinase and phosphatidylinositol 3-kinase signaling pathways

Despite being a well-characterized neurotrophic factor, nerve growth factor (NGF) influences survival, differentiation, and functions of mast cells. We investigated whether NGF was able to induce directional migration of rat peritoneal mast cells (PMCs). NGF clearly induced chemotactic movement of PMCs in a dose-dependent manner with the drastic morphological change and distribution of F-actin, which was completely blocked by pretreatment with Clostridium botulinumC2 toxin, an actin-polymerization inhibitor. Because PMCs constitutively express the NGF high-affinity receptor (TrkA) with a tyrosine kinase domain, we focused on downstream effectors in signaling cascades following the TrkA. NGF rapidly activated both mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K), and the addition of inhibitors specific for MAPK kinase and PI3K suppressed cell migration and these signals. In the coculture system with PMCs and fibroblasts, which produce biologically active NGF, directional migration of PMCs to fibroblasts was observed, and the addition of anti-NGF polyclonal antibodies significantly suppressed the migration of PMCs. These findings suggested that NGF initiated chemotactic movement of PMCs through both MAPK and PI3K signaling pathways following TrkA activation. Thus, locally produced NGF may play an important role in mast cell accumulation in allergic and nonallergic inflammatory conditions.

Mast cells enhance contraction of three-dimensional collagen lattices by fibroblasts by cell-cell interaction: role of stem cell factor/c-kit

Reorganization of the extracellular matrix is important in many biological and pathophysiological processes, including tissue remodelling, wound healing, or cancer metastasis. The ability of cultured fibroblasts to reorganize and contract three-dimensional type I collagen gels is regarded as an in vitro model for this process. In tissue fibrosis, complex interactions among fibroblasts, inflammatory cells and the extracellular matrix are taking place. Mast cells have often been discussed to play a role in several fibrotic conditions including scleroderma, scar formation, or wound healing. In this study, we examined the effects of mast cells on contraction of collagen lattices. The results demonstrate that co-culture of dermal fibroblasts with a human mast cell line (HMC-1) significantly enhanced contraction of the three-dimensional collagen lattices, whereas mast cells alone failed to contract the gel. Addition of culture supernatants of mast cells did not enhance the speed of gel contraction, indicating the importance of cell-cell contact. Morphological analysis showed that mast cells were incorporated into the lattices. Histological examination also demonstrated that within the lattices, mast cells were localized in close contact to, or attached to, fibroblasts. As fibroblasts and mast cells are known to attach via stem cell factor (SCF)/c-kit interaction when co-cultured in monolayers, we also examined the effect of antibodies against SCF and c-kit in this system. Addition of both antibodies inhibited gel contraction up to 70%. In contrast, antibodies against interleukin-4 (IL-4) and IL-4 receptor did not affect gel contraction. These results indicate that mast cells enhance fibroblast-mediated contraction of collagen lattices via direct cell-cell contact, mediated in part by SCF/c-kit interactions.

Mastocytosis with skin manifestations: current status

AIM

To review our present knowledge about mastocyte origin, mastocytosis classification and management.

METHODS

Literature review.

RESULTS

Mastocytoses are chronic and recurrent disorders with symptoms which might either be limited only to the skin or to internal organs as well. The mastocytes, coming from bone marrow progenitor cells, migrate to tissues where they participate in inflammation and in cellular immunity as well as in the metabolism of connective and osseous tissues. Their proliferation causes the appearance of mastocytoses. The classification of the clinical manifestations of the mastocytoses into cutaneous, reactive (under the influence of the degranulator factors) and systemic disease, facilitates dialog among clinicians. Determination of prognosis and appropriate therapeutic regimens depend on individual features.

CONCLUSIONS

Mastocytosis diagnosis is verified by histological study of skin lesion biopsy material. Management is symptomatic and unfortunately does not eradicate the disease.

A barium method for the cytochemical detection of sulfated glycosaminoglycans in mast cells and basophilic leukocytes

Barium ions precipitate inorganic as well as organic sulfate compounds and they can be detected by a reaction with sodium rhodizonate. In this work, we describe the use of a barium method for the selective demonstration of sulfated glycosaminoglycans in cytoplasmic granules of mast cells and basophilic leukocytes. Methanol-fixed smears of mouse peritoneal mast cells and rat bone marrow basophils were treated with 5% BaCl2 for 10 min, followed by staining with either 0.2% sodium rhodizonate in 50% ethanol for 2 h at 60 degrees C, or 0.01% brilliant green in distilled water for 1 min. Light microscopic observation revealed a strong staining reaction of the cytoplasmic granules of these cell types, which was more selective when using sodium rhodizonate. Control smears treated with BaCl2 or sodium rhodizonate alone, and those subjected to methylation/extraction of sulfate groups before staining remained unstained. The selective binding of barium ions to mast cell granules was established with scanning electron microscopy using a backscattered electron detector, and confirmed by energy dispersive X-ray microanalysis as well as element mapping.

The clinical expression of allergy in the skin

The cutaneous immune system has evolved to protect the organism from potential exogenous pathogens in a complex manner. Recent investigations of the special role of the skin in allergy have focused on the proinflammatory potential of various cells such as Langerhans' cells, keratinocytes, mast cells (MC), endothelial cells, and dermal fibroblasts. Furthermore, in processing and reacting to antigens, infiltrating inflammatory cells (lymphocytes; monocytes; macrophages; and eosinophil, neutrophil, and basophil granulocytes) play an important role both by cell-cell interactions with specific receptors on cell surfaces and via soluble mediators.

Contribution of mast cells to the tubulointerstitial lesions in IgA nephritis

BACKGROUND

Mast cells have never been extensively investigated in renal disease, particularly glomerulonephritis. Recent improvements in monoclonal antibody production to mast cell specific enzymes have made it possible to study mast cells in tissues more accurately and easily. Mast cells have been found to secrete basic fibroblast growth factor (bFGF) in human pulmonary fibrosis.

METHODS

Mast cells in 67 cases of IgA nephritis were investigated. Toluidine blue (TB) stainings at pH 5.0 and pH 0.5 were employed histochemically, and anti-human mast cell tryptase and chymase monoclonal antibodies were used immunohistochemically. Anti-bFGF antibody was also used immunohistochemically.

RESULTS

Mast cells were scattered in the interstitium including in fibrotic areas. TB pH 0.5-positive mast cells were more numerous than TB pH 5. 0-positive mast cells. Immunostaining with anti-tryptase monoclonal antibody detected more mast cells than the TB stainings. Mast cells in the interstitium of IgA nephritis had both tryptase and chymase. Immunoelectron microscopy showed that tryptase was exclusively localized in the specific granules of mast cells. The average number of tryptase positive mast cell in the interstitium of IgA nephritis was lower than that of T lymphocyte but more than that of macrophages. The average number of mast cells increased with the progression of interstitial fibrosis and had a significant correlation with 24-hour creatinine clearance. Using double labeled immunohistochemistry, some tryptase-positive mast cells had bFGF in their cytoplasm. Electron microscopy showed that mast cells were associated with fibroblasts and/or lymphocytes in the interstitium.

CONCLUSION

Mast cells are one of the constitutive cells in the interstitium of IgA nephritis patients and affect renal function by contributing to the interstitial fibrosis.

Expression of basic fibroblast growth factor in nasal polyps

Basic fibroblast growth factor (bFGF) is a polypeptide that is mitogenic for a wide variety of cell types. We used Northern blot analysis and immunohistochemistry to determine if bFGF is expressed in the nasal polyp tissue; bFGF messenger RNA was detectable in the polyps examined by Northern blot analysis. Strong immunostaining for bFGF was found in blood vessels and along the basement membrane of the epithelial cell layers. Basal epithelial cells and some infiltrating mononuclear cells also stained for bFGF. Proliferating cell nuclear antigen colocalized with bFGF to basal epithelial cells, endothelial cells, and areas of focal epithelial metaplasia. The polyp tissue was double-labeled with a mouse monoclonal antitryptase, a specific mast cell marker, and anti-bFGF. A significant number (65% +/- 19%) of the bFGF-positive mononuclear cells in the polyp tissues were positive for tryptase. These findings suggest that bFGF may contribute to the endothelial and epithelial proliferation in nasal polyp tissues and that mast cells are one source of this growth factor.

Ultrastructural immunolocalization of basic fibroblast growth factor in mast cell secretory granules. Morphological evidence for bfgf release through degranulation

We previously reported that mast cells (MCs) serve as a source of basic fibroblast growth factor (bFGF), a potent angiogenic and mitogenic polypeptide, suggesting that bFGF may mediate MC-related neovascularization and fibroproliferation. Unlike many other growth factors, bFGF lacks a classic peptide sequence for its secretion, and the mechanism(s) for its release remains controversial. Because MCs release a wide spectrum of bioactive products via degranulation, we hypothesized that MC degranulation may be a mechanism of bFGF release and used ultrastructural immunohistochemistry to test the hypothesis. We reasoned that if bFGF is released through degranulation, it should be localized to MC secretory granules. Human tissues with chronic inflammation and rat/mouse tissues with anaphylaxis were studied. In all tissue samples examined, positive staining (or immunogold particle localization) for bFGF in MCs was predominantly in the cytoplasmic granules. Moderate bFGF immunoreactivity was also found in the nucleus, whereas the cytosol and other subcellular organelles exhibited minimal immunogold particle localization. In contrast, no immunogold particle localization for bFGF was observed in lymphocytes or plasma cells. In rat/mouse lingual tissue undergoing anaphylaxis, immunogold particle localization for bFGF was found not only in swollen cytoplasmic granules but also in the extruded granules of MCs. Three different anti-bFGF antibodies gave similar immunogold particle localization patterns, whereas all controls were negative. These results provide morphological evidence suggesting that, despite the lack of a classic secretory peptide in its structure, bFGF is localized to the secretory granules in MCs and may be released through degranulation.

Lymphadenopathy, elevated serum IgE levels, autoimmunity, and mast cell accumulation in flaky skin mutant mice

The autosomal recessive mutation "flaky skin" (fsn) causes pleiotropic abnormalities in the immune and hematopoietic systems accompanied by pathologic changes in the skin. Homozygotes (fsn/fsn) showed increased size and histological alterations in the spleen and lymph nodes. Abnormalities in lymphoid architecture of the spleen in fsn/fsn mice were accompanied by marked increases in total numbers of B cells, macrophages, and immature erythroid cells. Splenic B cells displayed elevated MHC class II expression. Serum IgE levels were greater than 100 microg/ml by 10 weeks of age, representing > 7000-fold increase compared with normal littermates. This increased IgE level was associated with elevated IL-4 production by spleen cells and with increased amounts of serum IL-4. Serum IgM, IgG1, and IgG2b levels were also increased in fsn/fsn mice while IgG3 was decreased. Autoimmunity in fsn/fsn mice was evidenced by glomerulonephritis accompanied by immune complex deposition in the kidneys, increased serum blood urea nitrogen levels, and the presence of circulating anti-double-stranded DNA autoantibodies. Pathological changes in the skin of fsn/fsn mice were characterized by epidermal hyperplasia and mixed dermal inflammation. Increased numbers of mast cells were also observed in the dermis of the truncal skin as well as in the epithelial stomach. These marked immunological abnormalities suggest that the fsn locus encodes a major immunoregulatory molecule important in multiple immune and hematopoietic functions.