Human mast cells produce IL-13 by high-affinity IgE receptor cross-linking: enhanced IL-13 production by IL-4-primed human mast cells

Induction of IL-13 production and upregulation of gene expression of protease activated receptors in P815 cells by IL-6

Interleukin (IL)-6 is a multifunctional cytokine which has been showed to induce up-regulated expression of Fc epsilon RI receptor and histamine production in mast cells. However, little is known of its effects on Th2 cytokine secretion and protease activated receptor (PAR) expression in mast cells. In the present study, we examined potential influence of IL-6 on IL-13, IL-4 and IL-10 release from P815 cells and PAR expression on P815 cells by using flow cytometry analysis, quantitative real-time PCR, ELISA and cellular activation of signaling ELISA (CASE) techniques. The results showed that IL-6 induced up to 1.8-fold increase in IL-13, but not IL-4 or IL-10 release from P815 cells, and FSLLRY-NH(2) did not affect IL-6 induced IL-13 release. Tryptase elicited 2.0-fold increase in IL-13 release from P815 cells, which can be inhibited by IL-6. IL-6 elicited the up-regulated expression of PAR-1, PAR-2, PAR-3 and PAR-4 mRNAs, but had little effects on expression of PAR proteins. U0126, PD98059 and LY204002 abolished IL-6 induced IL-13 release when they were preincubated with P815 cells, indicating ERK and Akt cell signaling pathways may be involved in the event. In conclusion, IL-6 can stimulate IL-13 release from mast cells through an ERK and Akt cell signaling pathway dependent, but PAR independent mechanism.

Therapeutic efficacy of Cintredekin Besudotox (IL13-PE38QQR) in murine lung fibrosis is unaffected by immunity to Pseudomonas aeruginosa exotoxin A

BACKGROUND

We have previously explored a therapeutic strategy for specifically targeting the profibrotic activity of IL-13 during experimental pulmonary fibrosis using a fusion protein comprised of human IL-13 and a mutated form of Pseudomonas aeruginosa exotoxin A (IL13-PE) and observed that the intranasal delivery of IL13-PE reduced bleomycin-induced pulmonary fibrosis through its elimination of IL-13-responsive cells in the lung. The aim of the present study was to determine whether the presence of an immune response to P. aeruginosa and/or its exotoxin A (PE) would diminish the anti-fibrotic properties of IL13-PE.

METHODOLOGY/PRINCIPAL FINDINGS

Fourteen days after P. aeruginosa infection, C57BL/6 mice were injected with bleomycin via the intratracheal route. Other groups of mice received 4 doses of saline or IL13-PE by either intranasal or intraperitoneal application, and were challenged i.t. with bleomycin 28 days later. At day 21 after bleomycin, all mice received either saline vehicle or IL13-PE by the intranasal route and histopatological analyses of whole lung samples were performed at day 28 after bleomycin. Intrapulmonary P. aeruginosa infection promoted a neutralizing IgG2A and IgA antibody response in BALF and serum. Surprisingly, histological analysis showed that a prior P. aeruginosa infection attenuated the development of bleomycin-induced pulmonary fibrosis, which was modestly further attenuated by the intranasal administration of IL13-PE. Although prior intranasal administration of IL13-PE failed to elicit an antibody response, the systemic administration of IL13-PE induced a strong neutralizing antibody response. However, the prior systemic sensitization of mice with IL13-PE did not inhibit the anti-fibrotic effect of IL13-PE in fibrotic mice.

CONCLUSIONS

Thus, IL13-PE therapy in pulmonary fibrosis works regardless of the presence of a humoral immune response to Pseudomonas exotoxin A. Interestingly, a prior infection with P. aeruginosa markedly attenuated the pulmonary fibrotic response suggesting that the immune elicitation by this pathogen exerts anti-fibrotic effects.

Interaction between prostaglandin D and chemoattractant receptor-homologous molecule expressed on Th2 cells mediates cytokine production by Th2 lymphocytes in response to activated mast cells

The mechanisms by which immunologically activated mast cells stimulate the production of proinflammatory cytokines by T helper type 2 (Th2) lymphocytes were investigated in a human cell culture system. Supernatants collected from cord blood-derived mast cells after treatment with immunoglobulin E (IgE)/anti-IgE contained an activity that stimulated the production of interleukin (IL)-4, IL-5 and IL-13 (both mRNA and protein) by Th2 lymphocytes. This activity was not detected in supernatants from unactivated mast cells and its production was inhibited by treatment of activated mast cells with the cyclo-oxygenase inhibitor diclofenac. The concentration of diclofenac used inhibited completely the production of prostaglandin D(2) (PGD(2)) but did not inhibit the release of histamine or leukotriene C(4). The effect of supernatants from activated mast cells was mimicked by exogenous PGD(2) at concentrations similar to those detected in the cultures of activated mast cells, and addition of exogenous PGD(2) to supernatants from diclofenac-treated mast cells restored their ability to stimulate Th2 cytokine production. The ability of the mast cell supernatants to stimulate production of Th2 cytokines was not affected by addition of diclofenac to the Th2 cells directly, indicating that the production, but not the action, of the factor was sensitive to diclofenac treatment. Inhibition of chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) abolished the effect of the mast cell supernatants on Th2 cytokine production. These data indicate that mast cells have the ability to stimulate Th2 cells to elaborate cytokines independently of T cell receptor activation or co-stimulation and this response is mediated by PGD(2) acting upon CRTH2 expressed by Th2 cells.

Interleukin-13 promoter gene polymorphism -1112C/T is associated with the systemic form of mastocytosis

BACKGROUND

Mastocytosis is a heterogenous disease involving mast cells (MC) and their progenitors. Cutaneous and systemic variants of the disease have been reported. In contrast to cutaneous mastocytosis (CM), patients with systemic mastocytosis (SM) are at risk to develop disease progression or a nonMC-lineage haematopoietic neoplasm. Little is known, however, about factors predisposing for the development of SM. One factor may be cytokine regulation of MC progenitors.

METHODS

We examined the role of the interleukin-13 (IL-13) promoter gene polymorphism -1112C/T, known to be associated with increased transcription, in mastocytosis using allele-specific polymerase chain reaction method. Serum tryptase and IL-13 levels were determined by immunoassay, and expression of the IL-13 receptor in neoplastic MC by reverse transcription-polymerase chain reaction and flow cytometry.

RESULTS

The frequency of the -1112T allele of the IL-13 promoter was significantly higher in patients with SM compared with CM (P < 0.008) and in mastocytosis patients compared with healthy controls (P < 0.0001). Correspondingly, the polymorphism was found to correlate with an elevated serum tryptase level (P = 0.004) and with adult-onset of the disease (P < 0.0015), both of which are almost invariably associated with SM. Serum IL-13 levels were also higher in SM patients compared with CM (P = 0.011), and higher in CT- than in CC carriers (P < 0.05). Finally, we were able to show that neoplastic human MC display IL-13 receptors and grow better in IL-13-containing medium.

CONCLUSIONS

The -1112C/T IL-13 gene polymorphism and the resulting 'hypertranscription' may predispose for the development of SM.

Pathological evaluation of uterine leiomyomas treated with gonadotropin-releasing hormone agonist (GnRH-a) therapy: role of mast cells and a possible mechanism of GnRH-a resistance in leiomyomas

Gonadotropin-releasing hormone agonist (GnRH-a) therapy is frequently applied to reduce the volume of uterine leiomyomas (UL). In addition, the possible relationship between mast cells (MC) within UL and the development of UL has been suggested, but the role of MC in UL remains to be determined. UL with or without GnRH-a therapy in 121 premenopausal patients were reviewed. The number of MC was evaluated between the two groups, immunohistochemistry was done for insulin-like growth factor-I (IGF-I), and the association between the IGF-I immunoreactivity in UL and the GnRH-a therapy was analyzed. The number of MC significantly increased in UL in GnRH-a therapy, while IGF-I immunoreactivity was significantly reduced in smooth muscle cells of these UL. Furthermore, IGF-I immunoreactivity in MC was inversely correlated with the size reduction rate of UL in GnRH-a therapy. Although GnRH-a therapy is considered to reduce the size of UL transiently, the regression of UL was in part hampered by the increased IGF-I secretion from the increased MC after GnRH-a therapy. Therefore, the more the IGF-I secretion from MC in UL increases, the less effective the GnRH-a therapy is on the size reduction of UL. Thus, the present study may provide an explanation of the possible mechanism of GnRH-a resistance in UL.

Progress in allergy signal research on mast cells: systemic approach to mast cell biology in allergic diseases

At the end of the last century, microarray technology that examines the total genes and transcripts present in a cell became available as a laboratory tool. Mast cells are known to play a pivotal role in initiating allergic inflammation by releasing various mediators and cytokines. According to the recent microarray-based studies, mast cells have been found to be much more versatile functional molecules than we ever thought. Also, genes that are exclusively expressed in mast cells have been identified in comparison with other cell types. In this article, the outcome of microarray-based analyses on the role of mast cells in allergic inflammation will be reviewed by focusing on the mast cell-specific genes as drug targets.

Mast cell production of IL-4 and TNF may be required for protective and pathological responses in gastrointestinal helminth infection

Expulsion of the gastrointestinal nematode Trichinella spiralis is associated with Th2 responses and intestinal inflammation, which correlate with a marked mast cell (MC) response. To address the role of MC-derived cytokines in the induction of protective responses, WBB6F1-KitW/KitW-v (W/W(v)) mice were reconstituted with wild-type, tumor necrosis factor (TNF)-alpha(-/-), or interleukin (IL)-4(-/-) bone marrow (BM) prior to infection with T. spiralis. W/W(v) mice reconstituted with TNF-alpha(-/-) or IL-4(-/-) BM expelled the parasite less efficiently and showed diminished enteropathy, whereas protective responses were normal in W/W(v) mice reconstituted with wild-type BM and were accompanied by intestinal pathology. MC responses were reduced in W/W(v) mice reconstituted with IL-4(-/-) BM and to a lesser extent when reconstituted with TNF-alpha(-/-). These results suggest that MC-derived IL-4 and TNF may regulate the induction of protective Th2 responses and intestinal inflammation associated with the expulsion of T. spiralis. Significantly, these studies suggest a role for MC-derived cytokines as autocrine growth factors.

Inhibition of human cord blood-derived mast cell responses by anti-Fc epsilon RI mAb 15/1 versus anti-IgE Omalizumab

Aggregation of the alpha-chain of the high affinity IgE receptor (Fc epsilon RI alpha) on mast cells or basophils after cross-linking of receptor-bound IgE by its antigen or an anti-IgE antibody results in cell activation and release of inflammatory mediators. Omalizumab (Xolair), Novartis Pharmaceuticals; Genentech Inc.) is a recombinant humanized anti-IgE mAb developed for the treatment of severe allergic asthma. It complexes with free serum IgE, which prevents its binding to Fc epsilon RI and thereby interrupts the allergic cascade. Administration of an inhibitory anti-Fc epsilon RI alpha mAb may represent an alternative strategy to neutralize IgE-mediated receptor activation. In the present report, for the first time, we have performed direct side of side comparison between the inhibitory anti-Fc epsilon RI alpha mAb designated 15/1 and Omalizumab for their effects on human cord blood-derived mast cells. We provide the first evidence that both 15/1 mAb and Omalizumab efficiently inhibit Fc epsilon RI-mediated human mast cell responses in vitro (degranulation, activation, release of IL-8 and IL-13, phosphorylation of Akt) and that mAb 15/1 is a non-anaphylactogenic antibody, which compared to Omalizumab, displays markedly higher inhibitory potency in the presence of high IgE levels.

A polymorphism of MS4A2 (- 109T > C) encoding the beta-chain of the high-affinity immunoglobulin E receptor (FcepsilonR1beta) is associated with a susceptibility to aspirin-intolerant asthma

BACKGROUND AND OBJECTIVE

The MS4A2 gene, the beta chain of the high-affinity receptor for immunoglobulin (Ig)E, has previously been linked to atopy and asthma. The beta-chain of FcepsilonR1 enhances receptor maturation and signal transduction capacity, leading to the release of proinflammatory mediators and cytokines that can exacerbate the symptom of asthma. This study was performed to evaluate whether two genetic polymorphisms of the FcepsilonR1beta gene (FcepsilonR1beta-109T > C and FcepsilonR1beta E237G) are associated with aspirin-intolerant asthma (AIA). The MS4A2 gene polymorphisms (FcepsilonR1beta-109T > C and FcepsilonR1beta E237G) were determined by SNP-IT assays in patients with AIA (N = 164), aspirin-tolerant asthma (ATA, N = 144) and normal controls (NC, N = 264) recruited from a Korean population.

RESULTS

The genotype frequencies of FcepsilonR1beta-109T > C and E237G polymorphisms were not significantly associated with the pathogenesis of AIA. However, FcepsilonR1beta-109T > C polymorphism was significantly associated with the presence of specific IgE to Staphylococcal enterotoxin B (SEB); the number of subjects carrying both homozygous TT genotype of FcepsilonR1beta-109T > C and specific IgE to SEB was significantly higher in the AIA group when compared with the other control groups (P = 0.01, odds ratio (OR) = 7.723, 95% confidence interval (CI) = 1.327-39.860 for AIA vs. ATA; P = 0.02, OR = 6.364, 95% CI = 1.149 approximately 35.229 for AIA vs. NC). In addition, luciferase reporter assays also showed that the FcepsilonR1beta-109T allele was associated with higher promoter activity of MS4A2 in both RBL-2H3 and A549 cell lines.

CONCLUSION

FcepsilonR1beta-109T > C polymorphism may increase expression of MS4A2 by mast cells, leading to enhanced release of proinflammatory mediators in the asthmatic airway, contributing to increased susceptibility to AIA.

Mast cells express IL-13R alpha 1: IL-13 promotes human lung mast cell proliferation and Fc epsilon RI expression

BACKGROUND

The Th2 cytokine interleukin (IL)-13 is implicated in the development of various allergic diseases including asthma. The IL-13 receptor, IL-13Ralpha1, is expressed on most leukocytes, except T-cells. Evidence to support IL-13Ralpha1 expression on mast cells is limited.

METHODS

We investigated: (i) IL-13Ralpha1 expression by human lung mast cells (HLMC); (ii) the number of IL-13Ralpha1+ bronchial submucosal mast cells in subjects with asthma and normal controls and (iii) the effect of IL-13 priming on HLMC expression of high-affinity IgE receptor (FcepsilonRI), stem cell factor receptor (CD117), histamine release, proliferation, and survival.

RESULTS

Human lung mast cell expressed IL-13Ralpha1 mRNA. IL-13Ralpha1 was highly expressed on the surface HLMC (82+/-9%). Bronchial submucosal mast cell IL-13Ralpha1 expression was higher in asthmatics (86+/-2%) than normal controls (78+/-2%; P=0.015). IL-13 priming for 30 min did not increase HLMC histamine release, in the presence or absence of SCF or in response to IgE/anti-IgE activation. IL-13 priming for 5 days upregulated HLMC FcepsilonRI expression (22% increase in fluorescent intensity; P=0.003), increased histamine release following IgE/anti-IgE activation by 56% (P=0.03) and increased proliferation by 50% (P=0.003) without affecting cell survival or CD117 expression. The IL-13 specific neutralizing antibody CAT-354 inhibited all IL-13 mediated effects.

CONCLUSION

Human lung mast cell express IL-13Ralpha1 and activation by IL-13 for 5 days increased FcepsilonRI expression and proliferation. Histamine release was not affected by short-term priming with IL-13, but was upregulated by priming for 5 days suggesting that this effect was mediated by the increased FcepsilonRI expression. These data support the view that targeting IL-13 may be beneficial in the treatment of asthma.

IL-4 regulates MEK expression required for lysophosphatidic acid-mediated chemokine generation by human mast cells

IL-4 and mast cells (MCs) mediate mucosal defense against helminths and are central to allergic inflammation. Lysophosphatidic acid (LPA), an abundant, potent lipid growth factor, stimulates the growth of cultured human MCs (hMCs) in vitro through a pathway involving LPA receptors 1 and 3 (termed the LPA(1) and LPA(3) receptors, respectively) and peroxisome proliferator-activated receptor-gamma. We now report that LPA potently induces the generation of proinflammatory chemokines (MIP-1beta, IL-8, and MCP-1) by hMCs by a mechanism that absolutely requires IL-4. The de novo expression of chemokine mRNA and protein generation involves synergistic actions of calcium flux-dependent NFAT transcription factors and ERK. ERK phosphorylation and chemokine production in response to LPA require IL-4-dependent up-regulation of MEK-1 expression by a pathway involving PI3K. Although receptor-selective agonists for both the LPA(2) and LPA(3) receptors induce calcium fluxes by hMCs, only the LPA(2) receptor-selective agonist fatty alcohol phosphate-12 mimics the IL-4-dependent effect of LPA on chemokine generation. The fact that LPA, an endogenous lipid mediator, activates hMCs by an LPA(2) receptor-dependent pathway indicates functional distinctions between different LPA receptor family members that are expressed constitutively by cells of a single hemopoietic lineage. Moreover, the regulation of MEK-dependent signaling is a mechanism by which IL-4 could amplify inflammation in mucosal immune responses through receptor systems for endogenous ligands such as LPA.

Cytokine Production by Skin-Derived Mast Cells: Endogenous Proteases Are Responsible for Degradation of Cytokines

The current study characterizes the cytokine protein (ELISA) and mRNA (gene array and RT-PCR) profiles of skin-derived mast cells cultured under serum-free conditions when activated by cross-linking of Fc epsilonRI. Prior to mast cell activation, mRNA only for TNF-alpha was detected, while after activation mRNA for IL-5, IL-6, IL-13, TNF-alpha, and GM-CSF substantially increased, and for IL-4 it minimally increased. However, at the protein level certain recombinant cytokines, as measured by ELISAs, were degraded by proteases released by these skin-derived mast cells. IL-6 and IL-13 were most susceptible, followed by IL-5 and TNF-alpha; GM-CSF was completely resistant. These observations also held for the endogenous cytokines produced by activated mast cells. By using protease inhibitors, chymase and cathepsin G, not tryptase, were identified in the mast cell releasates as the likely culprits that digest these cytokines. Their cytokine-degrading capabilities were confirmed with purified chymase and cathepsin G. Soy bean trypsin inhibitor, when added to mast cell releasates, prevented the degradation of exogenously added cytokines and, when added to mast cells prior to their activation, prevented degradation of susceptible endogenous cytokines without affecting either degranulation or GM-CSF production. Consequently, substantial levels of IL-5, IL-6, IL-13, TNF-alpha, and GM-CSF were detected 24-48 h after mast cells had been activated, while none were detected 15 min after activation, by which time preformed granule mediators had been released. IL-4 was not detected at any time point. Thus, unless cytokines are protected from degradation by endogenous proteases, cytokine production by human mast cells with chymase and cathepsin G cells may be grossly underestimated.

Increase of activated mast cells in human endometriosis

PROBLEM

The proliferation of stromal cells in endometriosis promotes extensive adhesion; therefore, the morphological analysis of stromal lesions is important in the investigation of the pathogenesis of endometriosis.

METHOD OF STUDY

In this study, the morphological and numeric comparisons of degranulated mast cells were performed between endometriotic lesions and comparative regions (eutopic endometrium and normal uterine serosa) of patients with and without endometriosis.

RESULTS

In cases of endometriosis, diffuse infiltration of numerous mast cells was observed throughout the stromal lesions. These mast cells exhibited degranulation, and scattered granules were also observed. In the eutopic endometrium and normal uterine serosa of both the endometriosis patients and the controls, mast cells were rarely detected.

CONCLUSIONS

These results suggest that an abnormal immune response, specifically a hypersensitivity reaction, is strongly related to endometriosis; our findings will be helpful in the development of methods for the treatment of endometriosis.

Therapeutic targeting of IL-4- and IL-13-responsive cells in pulmonary fibrosis

Severe forms of idiopathic interstitial pneumonia (IIP), such as usual interstitial pneumonia (UIP), can be impervious to modern steroid and immunosuppressive treatment regimens, thereby emphasizing the need for novel effective therapies. Understanding the cytokine networks that may affect immune and structural cell activation and, hence, the progression of these fatal fibrotic diseases, has been a focus in our research. In this regard, we have examined the role of interleukin (IL)-4 and IL-13 and their respective receptor subunits in this process. Examination of clinical surgical lung biopsies (SLBs) showed that IIP is characterized by the abnormal, heightened expression of the receptor subunits that bind IL-4 and IL-13. Specifically, IL-4Ralpha and IL-13Ralpha2 (the high-affinity IL-13 receptor subunit) was present in greater abundance in SLBs and fibroblasts from IIP patients compared with normal patients, who exhibited no evidence of pulmonary fibrosis. These clinical findings prompted us to investigate whether the targeting of pulmonary cell types that were highly responsive to IL-4 and IL-13 was a viable therapeutic option in IIP. Using a chimeric protein comprised of human IL-13 and a truncated version of an exotoxin from Pseudomonas (abbreviated IL13-PE), we observed that IL13-PE selectively targeted human pulmonary fibroblasts grown from IIP SLBs, whereas it had a minimal effect on fibroblasts grown from biopsies from normal patients. In murine models characterized by abnormal airway or interstitial fibrotic responses, the intranasal administration of IL13-PE significantly attenuated the fibrotic response through the targeting of IL-4Ralpha- and IL-13Ralpha2-expressing pulmonary cells, including monocytes, macrophages, and pulmonary fibroblasts. Together, these data demonstrate that IL-4 and IL-13 are required for the initiation and maintenance of pulmonary fibrosis, and highlight the importance of further investigation of anti-fibrotic therapeutics that prevent the action of both cytokines during clinical pulmonary fibrosis.

Long-term exacerbation by interleukin 13 of IgE-mediated eosinophilia in rats

Recent work shows that at least two cycles of antigen challenge applied in a 7-day interval are required to yield tissue eosinophil accumulation in IgE-passively sensitized rats. Since interleukin (IL)-13 is widely regarded as a key mediator in eosinophilic responses associated with mast cells and IgE, we investigated whether this cytokine could replace the first cycle of sensitization and challenge in its proeosinophilic role. We found that IL-13 (25 and 50 ng/cavity) injected into the rat pleural space led to eotaxin generation and a dose-dependent accumulation of eosinophils following IgE-passive sensitization and challenge 7 days later. IL-13 failed to cause eosinophil chemotaxis in vitro but induced eosinophil accumulation into the pleural cavity of naïve rats, which peaked 1 day and faded 72 h post-challenge. No changes were found 1 week after intrapleural injection of IL-13, except an approximately 40-50% increase in the number of adhered and non-adhered pleural mast cells. As recovered from the pleural effluent 1 week after IL-13, mast cells expressed the same amount of IgE bound on their surface as compared to controls. However, they generated 3-fold more LTC(4) following IgE-sensitization and challenge in vitro, keeping intact the amount of histamine released. Finally, pretreatment with zileuton (50 microg/cavity) 1 h before allergen challenge prevented eosinophil accumulation in those animals injected with IL-13 1 week before. In conclusion, our findings show that IL-13 causes a long-term exacerbation of the IgE-mediated eosinophilic response in a mechanism associated with heightened cysteinyl-leukotriene (cys-LT) production by resident mast cells.

Successful treatment of systemic mastocytosis with high-dose interferon-alfa: long-term follow-up of a case

Daily treatment of systemic mastocytosis with high-dose interferon-alfa often is not tolerated because of clinical or hematologic side effects. We report successful treatment of a patient with systemic mastocytosis, who was positive for the D816V mutation, with interferon alfa-2b at 10 million units three times per week. During 5 years of treatment, bone marrow infiltration by mast cells decreased from 50 to < or =5%, and there was a decrease (urinary N-methylhistamine excretion, 75%; serum tryptase concentration, 98%) or normalization (serum calcitonin value, urinary prostaglandin F2alpha excretion) of mast cell mediators. Side effects included mild depression (untreated) and biochemical hypothyroidism easily managed with supplemental levothyroxine.

Upregulation of interleukin-13 and its receptor in a murine model of bleomycin-induced scleroderma

BACKGROUND

Interleukin-13 (IL-13) has been implicated in the pathogenesis of fibrotic conditions. Previously, a murine model for scleroderma has been established by repeated local injections of bleomycin. This animal model enabled us to study local expression and production of IL-13 in skin lesions during disease progression.

METHODS

Dermal sclerosis (DSc) was induced by repeated subcutaneous injections of bleomycin (1 mg/ml) in C3H/HeJ mice. IL-13 and IL-4 expressions were examined by RT-PCR, ELISA and immunohistochemistry.

RESULTS

RT-PCR showed that both IL-4 and IL-13 mRNA levels in skin lesions were increased and peaked after 4 weeks of bleomycin treatment. Quantification by densitometry revealed up to 4.2- and 1.9-fold increases, respectively. Immunohistochemical localization showed in skin lesions expression of IL-13 on infiltrating inflammatory cells, including mononuclear cells and possibly mast cells, increased with DSc progression. IL-13 protein production was also significantly increased. In skin lesions, IL-13 receptor (IL-13R) alpha2 expression was augmented mainly in the infiltrating mononuclear cells after 4 weeks of bleomycin exposure. IL-13Ralpha2, but not IL-13Ralpha1, mRNA was upregulated in the whole skin after 4 weeks. On the contrary, mRNA expression of IL-13Ralpha1 and IL- 13Ralpha2 was significantly altered in the cultured fibroblasts derived from bleomycin-treated skin.

CONCLUSION

These data demonstrate that in skin lesions levels of IL-13 as well as its receptor increase in parallel with DSc progression, suggesting that IL-13 promotes the progression of cutaneous fibrosis/sclerosis in the murine model of bleomycin-induced scleroderma.

Mast cells are involved in inflammatory reactions during Complex Regional Pain Syndrome type 1

BACKGROUND

The Complex Regional Pain Syndrome type 1 (CRPS1) is a complication of surgery or trauma but spontaneous development is also described. Although the pathogenesis remains debatable, afferent, efferent and central nervous system mechanisms are proposed. Recently we showed involvement of the proinflammatory cytokines IL-6 and TNFalpha which is direct evidence for an inflammatory process. Many types of cells, such as activated T lymphocytes, monocytes, macrophages and skin resident cells like mast cells, could contribute to the production of cytokines. Involvement of mast cells is relatively easy to detect by measurement of tryptase.

AIM

To establish whether mast cells are involved in the inflammatory reactions during CRPS1.

METHODS

Twenty patients fulfilling the Bruehl criteria with CRPS1 in one extremity were studied. Impairment was assessed by registration of pain and measurement of differences in temperature, volume and mobility between the involved and uninvolved extremity. Blisters were made with a suction method in order to determine cytokines and mast cell derived tryptase in the involved and uninvolved extremity.

RESULTS

In the blister fluid a significant difference (median +/- interquartile range, Wilcoxon signed-ranks test P < 0.05) was found between the involved and uninvolved extremity in IL-6 [53.5 (17.3-225) versus 6.2 (2-20.3) pg/ml], TNFalpha [31 (15.5-131.5) versus 8 (4-39) pg/ml], and tryptase [37 (20.5-62.3) versus 12.5 (6.7-23.5) ng/ml]. There was a significant correlation (0.455) between the intensity of pain and tryptase levels in the involved extremity (Spearman's test, P < 0.05).

CONCLUSION

Mast cells are involved in inflammatory reactions during the CRPS1. Mast cells could play a role in the production of cytokines such as TNFalpha.

Adenosine-activated mast cells induce IgE synthesis by B lymphocytes: an A2B-mediated process involving Th2 cytokines IL-4 and IL-13 with implications for asthma

Adenosine provokes bronchoconstriction in asthmatics through acute activation of mast cells, but its potential role in chronic inflammation has not been adequately characterized. We hypothesized that adenosine up-regulates Th2 cytokines in mast cells, thus promoting IgE synthesis by B lymphocytes. We tested this hypothesis in human mast cells (HMC-1) expressing A(2A), A(2B), and A(3) adenosine receptors. The adenosine analog 5'-N-ethylcarboxamidoadenosine (NECA) (10 microM) increased mRNA expression of IL-1beta, IL-3, IL-4, IL-8, and IL-13, but not IL-2 and IFN-gamma. Up-regulation of IL-4 and IL-13 was verified using RT-PCR and ELISA; 10 microM NECA increased IL-13 concentrations in HMC-1 conditioned medium 28-fold, from 7.6 +/- 0.3 to 215 +/- 4 pg/ml, and increased IL-4 concentrations 6-fold, from 19.2 +/- 0.1 to 117 +/- 2 pg/ml. This effect was mediated by A(2B) receptors because neither the selective A(2A) agonist 2-p-(2-carboxyethyl)phenethylamino-NECA nor the selective A(3) agonist N(6)-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine reproduced it, and the selective A(2B) antagonist 3-isobutyl-8-pyrrolidinoxanthine prevented it. Constitutive expression of CD40 ligand on HMC-1 surface was not altered by NECA. Human B lymphocytes cocultured for 12 days with NECA-stimulated HMC-1 produced 870 +/- 33 pg IgE per 10(6) B cells, whereas lymphocytes cocultured with nonstimulated HMC-1, or cultured alone in the absence or in the presence of NECA, produced no IgE. Thus, we demonstrated induction of IgE synthesis by the interaction between adenosine-stimulated mast cells and B lymphocytes, and suggest that this mechanism is involved in the amplification of the allergic inflammatory responses associated with asthma.

Mouse mast cell protease-1 is required for the enteropathy induced by gastrointestinal helminth infection in the mouse

BACKGROUND & AIMS

The relationship between intestinal pathology and immune expulsion of gastrointestinal nematodes remains controversial. Immune expulsion of gastrointestinal helminth parasites is usually associated with Th2 responses, but the effector mechanisms directly responsible for parasite loss have not been elucidated. Mast cell hyperplasia is a hallmark of infection with gastrointestinal nematodes, in particular Trichinella spiralis. Although the precise mechanism by which mast cells induce expulsion of these parasites has not been elucidated, it has been proposed that mast cell mediators, including cytokines and granule chymases, act to create an environment inhospitable to the parasite, part of this being the induction of intestinal inflammation. Therefore, the aims of this study were to dissect the role of mast cells and mast cell proteases in the induction of parasite-induced enteropathy.

METHODS

Mast cell-deficient W/Wv and mouse mast cell protease-1 (mMCP-1)-deficient mice were infected with T. spiralis, and parasite expulsion, enteropathy, and Th2 responses were determined.

RESULTS

Expulsion of the parasite was delayed in both strains of mice compared with wild-type controls; additionally, in both cases, the enteropathy was significantly ameliorated. Although Th2 responses were significantly reduced in mast cell-deficient W/Wv mice, those from mMCP-1-deficient mice were similar to wild-type mice. Additionally, levels of TNF-alpha and nitric oxide were significantly reduced in both W/Wv and mMCP-1 deficient mice.

CONCLUSIONS

These results imply that mast cells may contribute to the induction of protective Th2 responses and, importantly, that the intestinal inflammation associated with gastrointestinal helminths is partly mediated by mMCP-1.

Neutralizing endogenous IL-6 renders mast cells of the MCT type from lung, but not the MCTC type from skin and lung, susceptible to human recombinant IL-4-induced apoptosis

Human cord blood-derived mast cells undergo apoptosis upon exposure to recombinant human (rh)IL-4 and become resistant to rhIL-4-induced apoptosis when cultured in the presence of rhIL-6. The current study extends these effects of rhIL-4 to different populations of human mast cells, namely fetal liver-derived mast cells, lung-derived mast cells, and skin-derived mast cells. Endogenous production of IL-6 appears to protect fetal liver-derived mast cells and those of the MC(T) phenotype from rhIL-4-mediated apoptosis, because neutralization of IL-6 renders these mast cells sensitive. In contrast, mast cells of the MC(TC) phenotype from skin and lung were resistant to IL-4-mediated apoptosis, even after neutralization of endogenous IL-6. MC(TC) cells were CD124(low), whereas those of the MC(T) cells were CD124(high). These observations extend the phenotypic differences between MC(T) and MC(TC) types of human mast cells to include different functional responses to IL-4.

Recombinant human (rh) stem cell factor and rhIL-4 stimulate differentiation and proliferation of CD3+ cells from umbilical cord blood and CD3+ cells enhance FcepsilonR1 expression on fetal liver-derived mast cells in the presence of rhIL-4

We previously reported that rhIL-4 induced apoptosis and rhIL-6 mediated protection of human mast cells derived from cord blood mononuclear cells. Based on the result, we attempted to obtain the phenotypes and differentiation of CD3+ cells from cord blood by investigating their cell surface markers in the presence of rhSCF plus rhIL-4. The effect of co-cultured CD3+ cells on fetal liver mast cells (FLMCs) was also determined. Phenotypes from cord blood-derived cells were analyzed by flow cytometry and cell numbers were determined. Fetal liver mast cells were cultured with cord blood-derived cells (mainly CD3+) in the presence of rhSCF and/or rhIL-4 and were analyzed to determine cell number and expression of Kit+ and FcepsilonR1. The percentage of CD3+ cells from cord blood-derived cells on day 0 was about 41 +/- 13.5%, following monocytes and granulocytes. CD3+ cells increased in number (1.5-fold) and purity (90%), whereas other cell types did not survive. More than 60% of CD3+ cells from cord blood at day 0 were CD4(-)CD8-. These double-negative cells dramatically decreased by 1 week of culture, while CD4+CD8+ cells increased in number and purity through 3 weeks of culture, and then decreased as greater numbers of single-positive T cells emerged. We also found that FcepsilonR expression on FLMC increased in the presence of rhIL-4, but was not affected by the T cells that developed from cord blood mononuclear cells. The results indicate that IL-4, a Th2 type cytokine, together with rhSCF, can induce T cell proliferations, differentiation, and maturation from cord blood progenitor cells.

A review of experimental studies on diesel exhaust particles and nasal epithelium alterations

The aim of the present review is to summarize biological events in nasal epithelium after short-term exposure to diesel exhaust particles (DEP). Therefore human, animal, and in vitro studies carried out since 1987 are reviewed. Short-term exposure results included qualitative alterations characterized by immediate nasal hyperresponsiveness, antioxidant responses, marked epithelial inflammation, and a specific humoral response. In addition, studies on combined DEP/allergen challenge reported that, besides their intrinsic deleterious properties, DEP produced adjuvant-like effects on the immediate and late-phase response to allergen challenge, since they are able to mimic effects occurring after allergen challenge. DEP act deeply in nasal epithelium by (1) directing cytokine gene expression toward a Th2 profile, (2) enhancing local antigen-specific immunoglobulin E (IgE) production, and (3) driving in vivo isotype switch to IgE. Furthermore, DEP can induce in allergic subjects sensitization to a neoallergen, sensitization that did not occur with exposure to the neoantigen alone. Particulate pollutants such as DEP, encountered in urban areas, are therefore thought to be contributing causal factors to the exaggerated sensitization to allergens in subjects with appropriate genetic predisposition, sensitization that they might not otherwise have experienced. These findings add weight to the hypothesis that DEP are involved in the increased prevalence of airway allergic diseases.

Mucosal T-cell phenotypes in persistent atopic and nonatopic rhinitis show an association with mast cells

BACKGROUND

Allergic rhinitis is characterized by selective expansion of T cell subsets with a CD4+ phenotype. Recently, we identified a subpopulation of nonallergic rhinitis subjects with increased epithelial mast cell and eosinophil populations, suggestive of local mucosal allergy. Previously, T cell subsets have not been characterized in this subselection of nonallergic subjects and furthermore, their relationship to mast cell and basophil effector cells remain unidentified.

OBJECTIVE

To determine if a subpopulation of nonallergic subjects with idiopathic rhinitis (IR) have localized allergy confined to their nasal mucosa by comparing the T cell subsets and major histocompatibility complex (MHC) II expressing cells to persistent allergic rhinitis (PAR). Furthermore, the relationship between T cell subsets and mast cells/basophils was investigated.

METHODS

None of the symptomatic patients in this study were clinically allergen-challenged. Nasal turbinate mucosa was removed from patients with PAR, IR and normal controls. Morphometry was performed on immunostained sections for T cell subset populations including CD3+, CD4+, CD8+, CD25+, CD45RA+, CD45RO+, human leucocyte antigen (HLA)-DRalpha (MHC class II), mast cell tryptase and for basophils.

RESULTS

Subjects with persistent allergic rhinitis differed to normal controls in showing significantly increased numbers of total (CD3+), activated (CD25+) and allergen-naïve (CD45RA+) T lymphocytes in their nasal mucosa (P < 0.025). The naïve CD45RA+ memory T cells correlated to mucosal mast cells in PAR (P = 0.03). IR patients differ to allergic subjects in showing significantly reduced numbers of epithelial HLA-DRalpha+ cells (P = 0.007), but increased numbers of CD8+ lymphocytes (P = 0.02). The CD8+ T cells correlated with mucosal mast cell numbers (P = 0.02). In both rhinitis groups, basophils were present in very low numbers obviating the need for statistical analysis.

CONCLUSION

PAR is characterized by increased numbers of CD3+, CD25+ and CD45RA+ T lymphocytes compared with normal mucosa. Allergic and nonallergic rhinitis groups can be separated by significant differences in the number of epithelial antigen presenting cells (APCs) (HLA-DRalpha+) and sub-epithelial activated (CD25+) T cells. Moreover, IR patients do not significantly differ to their allergic counterparts with respect to total (CD3+) and naïve (CD45RA+) T cell numbers, or numbers of epithelial activated (CD25+) lymphocytes. IR subjects show significantly increased numbers of CD8+ lymphocytes compared with control mucosa and although our findings suggest that the initiating inflammatory events may differ, both rhinitis groups show a similarity in pathology involving mucosal mast cells with an association to infiltrating T cells.

Generation of a large number of connective tissue type mast cells by culture of murine fetal skin cells

We describe a novel culture system for generating large numbers of murine skin-associated mast cells and distinguish their characteristics from bone marrow-derived cultured mast cells. Culture of day 16 fetal skin single cell suspensions in the presence of interleukin-3 and stem cell factor allowed expansion and maturation of mast cells in the presence of stromal cells. The average yield of mast cells after 2 wk was 7.3 million cells per fetus at a purity of 96%. These fetal skin-derived cultured mast cells increased their histamine content in a time-dependent manner to 3.6 pg per cell after 2 wk and 6.7 pg per cell after 4 wk. Phenotypic analyses revealed much greater expression of CD49b and CD81 and lesser expression of CD77 and CD102 on fetal skin-derived cultured mast cells as compared with bone marrow-derived cultured mast cells. These findings suggest a close similarity between fetal skin-derived cultured mast cells and freshly isolated cutaneous mast cells. Connective tissue mast cell characteristics of fetal skin-derived cultured mast cells were evidenced by: (1) their greater histamine content than bone marrow-derived cultured mast cells; (2) the presence of heparin; and (3) their degranulation in response to compound 48/80 and substance P. Importantly, fetal skin-derived cultured mast cells secreted greater amounts of interleukin-13 but much less MIP-1beta and interleukin-6 than bone marrow-derived cultured mast cells in response to ionomycin. Thus fetal skin-derived cultured mast cells have many characteristics distinct from bone marrow-derived cultured mast cells and can be used as a model of cutaneous mast cells to discern their functions.

FcεRI-dependent gene expression in human mast cells is differentially controlled by T helper type 2 cytokines

BACKGROUND

Mast cells (MCs) proliferate in response to T(H)2 cytokines and express genes de novo after activation. Limited information is available concerning the interplay between these events.

OBJECTIVE

We explored the potential for T(H)2 cytokines to alter activation-dependent gene expression by MCs.

METHODS

Cord blood-derived human (h)MCs maintained in stem cell factor (SCF) alone were compared with replicates treated with IL-4, IL-5, or IL-9, respectively, for their patterns of FcepsilonRI-dependent gene induction using microarray technology.

RESULTS

Activation of SCF-treated hMCs upregulated their expression of roughly 140 transcripts at 2 hours, including genes involved in cell cycle progression and arrest. Each cytokine substantially modified this profile; approximately 800 inducible genes apiece were controlled by IL-5 or IL-9, whereas 169 inducible genes were controlled by IL-4. IL-4 favored the induction of cytokines and of genes associated with cell growth arrest (GADD34, GAS-1, CIDE-A, INK4D, and BAX) and completely abolished the enhanced proliferation observed in the other 3 groups after activation. Conversely, IL-5 priming induced preferential upregulation of genes involved in cell proliferation and did not abolish thymidine incorporation.

CONCLUSIONS

T(H)2 cytokines differentially modulate gene induction in hMCs after FcepsilonRI cross-linkage. IL-4 uniquely controls cytokine gene expression by hMCs and might also limit their activation-driven proliferation.

Human cord blood-derived mast cells synthesize and release I-309 in response to IgE

Mast cells are the central mediating cells of allergic reactions. Binding of allergen specific IgE to high affinity IgE receptor (Fcepsilon RI) and subsequent binding of allergen by the IgE causes receptor cross-linking and activation. In a study examining the differential gene expression in human cord blood-derived mast cells (CBMCs) mediated by activation of Fcepsilon RI both with IgE and IgE followed by cross-linking with alpha-IgE, the chemokine I-309 was found to be upregulated. I-309 is the ligand for the CCR8 receptor and is responsible for chemoattraction of TH2 type T-cells. Interestingly, I-309 RNA and protein levels were elevated not only in response to IgE/alpha-IgE activation but also by IgE alone. In addition, the I-309 levels were augmented by growth of the CBMCs in the presence of the proinflammatory cytokine IL-4. GM-CSF and MIP-1alpha secretion was also induced by IgE. These results suggest that IgE, through the production and release of cytokines such as I-309, GM-CSF and MIP-1alpha could promote an inflammatory reaction in the absence of antigen stimulation of mast cells.

Therapeutic attenuation of pulmonary fibrosis via targeting of IL-4- and IL-13-responsive cells

Severe forms of idiopathic interstitial pneumonia (IIP), such as usual interstitial pneumonia, can be impervious to modern steroid and immunosuppressive treatment regimens, thereby emphasizing the need for novel effective therapies. Consequently, research attention has been directed toward understanding the cytokine networks that may affect fibroblast activation and, hence, the progression of certain IIPs. This led us to investigate whether the specific targeting of resident lung cells responsive to IL-4 and IL-13 exerted a therapeutic effect in an experimental model of IIP, namely the bleomycin-induced model of pulmonary fibrosis. IL-4, IL-13, and their corresponding receptor subunits, IL-4Ralpha, IL-13Ralpha1, and IL-13Ralpha2, were maximally expressed at the mRNA and protein levels in whole lung samples on day 21 or 28 after an intratracheal bleomycin challenge. The intranasal administration of an IL-13 immunotoxin chimeric molecule (IL13-PE) from days 21-28, but not for 1-wk periods at earlier times, after bleomycin challenge had a significant therapeutic effect on histological and biochemical parameters of bleomycin-induced pulmonary fibrosis compared with the control group. The intranasal IL13-PE therapy significantly reduced the numbers of IL-4 and IL-13 receptor-positive mononuclear cells and macrophages and the levels of profibrotic cytokine and chemokine in the lungs of bleomycin-challenged mice on day 28. Thus, this study demonstrates that IL-4- and/or IL-13-binding cells are required for the maintenance of pulmonary fibrosis induced by bleomycin and highlights the importance of further investigation of antifibrotic therapeutics that target these cells during pulmonary fibrosis.

Role of immunoreactions and mast cells in pathogenesis of human endometriosis -morphologic study and gene expression analysis-

STUDY OBJECTIVES

To investigate the pathophysiology of human endometriosis, we examined by morphological and molecular biological methods.

METHODS

Samples of ovarian endometriosis and normal ovarian tissues were obtained laparoscopically after informed consent. A morphological study by toluidine blue staining, immunohistochemistry of c-kit and electron microscopy demonstrated the localization of mast cells in the stromal lesions of endometriosis. Oligonucleotide microarrays were used for gene expression analysis.

RESULTS

Infiltration of numerous mast cells and development of fibrosis was observed throughout the stromal lesions. Gene expression analysis by oligonucleotide microarrays indicated inflammatory immunoreactions in the lesions. Expressions of the FCER1G and PGDS, which are considered to be mast cell-specific genes, were upregulated in the ovarian endometriotic lesions as compared to the normal ovarian tissues. Furthermore, expressions of genes associated with immunological inflammation, such as IL-8, GRO1, GRO2, CXCR4, MCP1, and those related to tissue remodeling (MMP, COL4A2, and COL5A2) were also higher in endometriotic lesions than in the normal ovarian tissue.

CONCLUSIONS

Thus it is likely that mast cells and their related inflammatory immunoreactions via chemokines play important roles in producing fibrosis and adhesions in endometriotic lesions.

The role of mast cells in asthma

While the role of mast cells in allergic reactions is unequivocal, their precise functions in asthma remain controversial. Mast cells uniquely populate all vascularized organs and tissues, including the upper and lower respiratory tree, even in healthy individuals. Histologic evidence suggests that asthma is accompanied by a mast cell hyperplasia in the inflamed mucosal epithelium and the adjacent smooth muscle. The mechanisms responsible for constitutive mast cell development have been partly elucidated. Moreover, both in vitro studies and in vivo disease models indicate that mast cells have a remarkably flexible program of gene expression, and this program can be drastically altered by the T-cell-derived Th2 cytokines relevant to asthma. Moreover, the role of mast cells in innate immunity is now firmly established, and the capacity for numerous microbial pathogens to initiate their activation in vitro and in vivo suggest mechanisms by which microbes could initiate disease exacerbations.

Is there a common mechanism of gastrointestinal nematode expulsion?

Parasitic gastrointestinal (GI) nematodes are one of the most commonly acquired infections in the world. Although they cause relatively little mortality, infections result in high levels of morbidity that can result in developmental consequences in infected children and cause significant economic loss in infected animals. Over the last 30 years there has been extensive research into the mechanisms controlling the expulsion of gastrointestinal nematodes. Although many of the effector mechanisms that contribute to the loss of the parasite have been defined, we still appear to be some way from understanding the actual cause of parasite loss. Part of this stems from the different responses induced by different gastrointestinal parasites. It is clear that a Th2 response is essential for the expulsion of GI helminths; however, each of the characteristic immunological effector mechanisms induced following infection with these parasites may not be required or may be insufficient in isolation, but together they operate to expel GI helminths. These responses then succeed more efficiently in some cases than in others to induce parasite expulsion. The contribution made by various effector mechanisms to the expulsion of these parasites may therefore be a reflection of both the niche which the parasite inhabits as well as possible evasive/suppressive mechanisms employed by the parasites. In this review the various aspects of parasite expulsion will be described and the controversial issues in the field will be discussed.

The central role of FcepsilonRI in allergy

The high-affinity receptor for immunoglobulin E (IgE), FcepsilonRI, plays a central role in the initiation and control of atopic allergic inflammation. On mast cells and basophils, the function of the receptor is well known and constitutes cellular degranulation and the release of various mediators. FcepsilonRI on antigen-presenting cells (APCs), however, does not lead to degranulation of preformed granula, but has different functions: signal transduction pathways like the activation of NF-kappaB are initiated to induce inflammatory cytokine gene expression. In addition, FcepsilonRI on APCs acts as an allergen-focusing structure and can efficiently amplify allergen presentation in an IgE-dependent manner. Recently, we and others have gained new insight into the regulation and function of FcepsilonRI on APCs, which has shed new light on the modulating effects of the immune system in atopic inflammation.

Mast cells: beyond IgE

Mast cells, historically known for their involvement in type I hypersensitivity, also serve critical protective and homeostatic functions. They directly recognize the products of bacterial infection through several surface receptor proteins, releasing proteases, cytokines, and eicosanoid mediators that recruit neutrophils, limit the spread of bacterial infection, and facilitate subsequent tissue repair. In vitro studies suggest that the spectrum of microbes capable of initiating mast cell activation is broad and extends to common respiratory viruses, mycoplasma, and even products of tissue injury, such as nucleotides. TH2-polarized inflammation elicits a reactive hyperplasia of mast cells at the involved mucosal surfaces in both mice and human subject. Several recombinant TH2 cytokines (IL-3, IL-4, IL-5, and IL-9) act synergistically with stem cell factor to facilitate proliferation of nontransformed human mast cells in vitro. IL-4 induces the expression of critical inflammation-associated genes by human mast cells, such as those encoding leukotriene C4 synthase, Fc(epsilon)RI, and several cytokines. Consequently, priming with IL-4 not only amplifies classical Fc(epsilon)RI-dependent mast cell activation but also dramatically alters the product profile of mast cells activated by innate signals and by chemical mediators of inflammation. Strikingly, IL-4 induces an activation response by mast cells to cysteinyl leukotrienes, which act through a receptor shared with uridine diphosphate to induce cytokine generation without exocytosis. It Is possible that alterations in mast cell phenotype by the TH2 milieu of allergy permits otherwise trivial infections or homeostatic chemical signals to initiate harmful inflammatory cascades and sustain tissue pathology. Drug development must take these nonclassical mast cell activation pathways into account without compromising the beneficial and protective functions of mast cells.

Biochemical and functional characterization of human transmembrane tryptase (TMT)/tryptase gamma. TMT is an exocytosed mast cell protease that induces airway hyperresponsiveness in vivo via an interleukin-13/interleukin-4 receptor alpha/signal transducer and activator of transcription (STAT) 6-dependent pathway

Transmembrane tryptase (TMT)/tryptase gamma is a membrane-bound serine protease stored in the secretory granules of human and mouse lung mast cells (MCs). We now show that TMT reaches the external face of the plasma membrane when MCs are induced to degranulate. Analysis of purified recombinant TMT revealed that it is a two-chain neutral protease. Thus, TMT is the only MC protease identified so far which retains its 18-residue propeptide when proteolytically activated. The genes that encode TMT and tryptase betaI reside on human chromosome 16p13.3. However, substrate specificity studies revealed that TMT and tryptase betaI are functionally distinct even though they are approximately 50% identical. Although TMT is rapidly inactivated by the human plasma serpin alpha(1)-antitrypsin in vitro, administration of recombinant TMT (but not recombinant tryptase betaI) into the trachea of mice leads to airway hyperresponsiveness (AHR) and increased expression of interleukin (IL) 13. T cells also increase their expression of IL-13 mRNA when exposed to TMT in vitro. TMT is therefore a novel exocytosed surface mediator that can stimulate those cell types that are in close proximity. TMT induces AHR in normal mice but not in transgenic mice that lack signal transducer and activator of transcription (STAT) 6 or the alpha-chain of the cytokine receptor that recognizes both IL-4 and IL-13. Based on these data, we conclude that TMT is an exocytosed MC neutral protease that induces AHR in lungs primarily by activating an IL-13/IL-4Ralpha/STAT6-dependent pathway.

Interleukin-13 fusion cytotoxin arrests Schistosoma mansoni egg-induced pulmonary granuloma formation in mice

Schistosoma mansoni egg-induced lung pathology requires the actions of interleukin (IL)-4 and IL-13. Because receptors for IL-4 and IL-13 share chains, we examined the effect of a fusion protein comprised of IL-13 and Pseudomonas exotoxin (IL13-PE) on the development of pulmonary granulomas in mice. At day 8 after an intravenous injection of live S. mansoni eggs, whole lung samples from IL13-PE-treated mice exhibited significantly lower IL-4 and IL-13 gene expression, smaller granulomas, decreased collagen levels, and increased IL-13 receptor alpha2 gene expression compared to controls. The therapeutic effects of IL13-PE were also observed at day 16 despite the termination of IL13-PE treatment at day 8. These studies demonstrate that targeting IL-4- and IL-13- responsive cells with IL13-PE effectively arrests S. mansoni egg granuloma formation.

Regulation of mast-cell and basophil function and survival by IgE

Mast cells and basophils are important effector cells in T helper 2 (T(H)2)-cell-dependent, immunoglobulin-E-associated allergic disorders and immune responses to parasites. The crosslinking of IgE that is bound to the high-affinity receptor Fc epsilon RI with multivalent antigen results in the aggregation of Fc epsilon RI and the secretion of products that can have effector, immunoregulatory or autocrine effects. This response can be enhanced markedly in cells that have been exposed to high levels of IgE, which results in the increased surface expression of Fc epsilon RI. Moreover, recent work indicates that monomeric IgE (in the absence of crosslinking) can render mast cells resistant to apoptosis induced by growth-factor deprivation in vitro and, under certain circumstances, can induce the release of cytokines. So, the binding of IgE to Fc epsilon RI might influence mast-cell and basophil survival directly or indirectly, and can also regulate cellular function.

Th2 cytokine regulation of type I collagen gel contraction mediated by human lung mesenchymal cells

Asthma is characterized by chronic inflammation of the airway wall with the presence of activated T helper 2 (Th2) lymphocytes. The current study assessed the ability of Th2 cytokines to modulate fibroblast-mediated contraction of collagen gels to determine if Th2 cytokines could contribute to tissue remodeling by altering mesenchymal cell contraction. Human fetal lung fibroblasts, human adult bronchial fibroblasts and human airway smooth muscle cells were cast into native type I collagen gels and allowed to contract in the presence or absence of IL (interleukin)-4, IL-5, IL-10, or IL-13. IL-4 and IL-13 but not IL-5 and IL-10 augmented collagen gel contraction in a concentration-dependent manner. Neither IL-4 nor IL-13 altered fibroblast production of transforming growth factor-beta or fibronectin. Both, however, decreased fibroblast prostaglandin (PG) E(2) release. Decreased PGE(2) release was associated with a decreased expression of cyclooxygenase 1 and 2 protein and mRNA. Indomethacin completely inhibited PGE(2) release and also augmented contraction. IL-4 and IL-13, however, added together with indomethacin further augmented contraction suggesting both a PGE-dependent and a PGE-independent effect. These findings suggest that IL-4 and IL-13 may modulate airway tissue remodeling and, therefore, could play a role in the altered airway connective tissue which characterizes asthma.

Cysteinyl leukotrienes and uridine diphosphate induce cytokine generation by human mast cells through an interleukin 4-regulated pathway that is inhibited by leukotriene receptor antagonists

We previously reported that interleukin (IL)-4 upregulates the expression of leukotriene C(4) synthase (LTC(4)S) by human cord blood--derived mast cells (hMCs), augments their high-affinity Fc receptor for IgE (Fc(epsilon)RI)-dependent generation of eicosanoids and cytokines, and induces a calcium flux in response to cysteinyl leukotrienes (cys-LTs) and uridine diphosphate (UDP) that is blocked by cys-LT receptor antagonists. We speculated that this IL-4-dependent, receptor-mediated response to the cys-LTs and UDP might induce cytokine generation by hMCs without concomitant exocytosis. Unlike hMCs maintained in cytoprotective stem cell factor (SCF) alone, hMCs primed for 5 d with IL-4 responded to UDP (1microM), LTC(4) (100 nM), and LTD(4) (100 nM) by producing IL-5, tumor necrosis factor (TNF)-alpha, and especially large quantities of macrophage inflammatory protein (MIP)-1beta de novo at 6 h, preceded by the induced expression of the corresponding mRNAs. Cys-LT- and UDP-mediated cytokine production by the primed hMCs occurred without histamine release or PGD(2) generation and was inhibited by the CysLT1 receptor antagonist MK571. Additionally, pretreatment of hMCs with MK571 or with the cys-LT biosynthetic inhibitor MK886 decreased IL-5 and TNF-alpha production in response to IgE receptor cross-linkage, implying a positive feedback by endogenously produced cys-LTs. Cys-LTs and UDP thus orchestrate a novel, IL-4-regulated, non-IgE-dependent hMC activation for cytokine gene induction that could be initiated by microbes, cellular injury, or neurogenic or inflammatory signals; and this pathobiologic event would not be recognized in tissue studies where hMC activation is classically defined by exocytosis.

Reduced efficacy of treatment of strongyloidiasis in HTLV-I carriers related to enhanced expression of IFN-gamma and TGF-beta1

Strongyloidiasis, a human intestinal infection caused by Strongyloides stercoralis (S. stercoralis), is difficult to cure with drugs. In particular, a decrease of the efficacy of treatment has been reported in patients dually infected with S. stercoralis and human T-cell leukaemia virus type I (HTLV-I), both of which are endemic in Okinawa, Japan. However, the factors influencing this resistance remain unclear. In the present study, patients infected with S. stercoralis, with or without HTLV-I infection, were treated with albendazole, followed up for one year and separated into two groups, cured and non-cured. The cure rate of S. stercoralis was lower in HTLV-I carriers (P < 0.05). Serum levels of S. stercoralis-specific IgA, IgE, IgG, IgG1 and IgG4 antibodies were estimated, and a decrease of IgE (P < 0.05) and an increase of IgG4 (P < 0.05) were observed in the non-cured group, especially in HTLV-I carriers. RT-PCR of cytokines using peripheral blood mononuclear cells revealed that S. stercoralis patients with HTLV-I showed a high frequency of expression of IFN-gamma and TGF-beta1, whereas those without HTLV-I showed no expression of these cytokines. IFN-gamma- and TGF-beta1-positive HTLV-I carriers showed a decrease of IgE (P < 0.05), an increase of IgG4 (P < 0.01) and a lower cure rate (P < 0.01) compared with those who were negative for both cytokines. These results suggest that persistent infection with HTLV-I affected S. stercoralis-specific immunity and reduced therapeutic efficacy.

Mast cells regulate IFN-gamma expression in the skin and circulating IgE levels in allergen-induced skin inflammation

BACKGROUND

Mast cells are important effector cells in IgE-mediated allergic reactions. They are present in normal skin and increased in skin lesions of patients with atopic dermatitis (AD).

OBJECTIVE

We used mice deficient in mast cells (W/W(v)) to assess the role of these cells in a murine model of allergen-induced skin inflammation induced by repeated epicutaneous sensitization with ovalbumin (OVA); the model exhibits many of the characteristics of AD.

METHODS

Mice deficient in mast cells were sensitized with OVA. Histologic and immunohistochemical examinations, as well as measurements of IL-4 and IFN-gamma mRNA, were performed on OVA-sensitized skin. Total and antigen-specific serum IgE levels were determined.

RESULTS

Infiltration in W/W(v) mice by mononuclear cells, T cells, and eosinophils in OVA-sensitized skin was comparable to that in wild-type (WT) controls. Expression of IL-4 mRNA in sensitized skin sites was similarly increased in WT and W/W(v) mice. However, IFN-gamma mRNA expression was significantly increased in sensitized skin of W/W(v) mice but not in that of WT controls. IL-4 mRNA was readily detectable in unsensitized skin of WT controls but not in that of W/W,(v) mice, whereas expression of IL-12 p40 mRNA was significantly increased in unsensitized skin of W/W(v) mice in comparison with WT controls. Total serum IgE levels were significantly increased after epicutaneous sensitization in W/W(v) mice in comparison with WT controls.

CONCLUSION

These results suggest that mast cells regulate IFN-gamma expression in the skin and IgE levels in the circulation in a model of allergen-induced skin inflammation with similarities to AD. This is important, given the role of IFN-gamma in keratinocyte injury in AD and the role of IgE-mediated reactions in exacerbating AD.

IL-13 fusion cytotoxin ameliorates chronic fungal-induced allergic airway disease in mice

IL-13 has emerged as a major contributor to allergic and asthmatic responses, and as such it represents an attractive target in these diseases. In this study, IL-13-responsive cells in the lung were targeted via the intranasal administration of IL-13-PE38QQR (IL-13-PE), comprised of human IL-13 and a derivative of Pseudomonas exotoxin, to Aspergillus fumigatus-sensitized mice challenged with A. fumigatus spores, or conidia. Mice received 50, 100, or 200 ng of IL-13-PE or diluent alone (i.e., control group) on alternate days from day 14 to day 28 after the conidia challenge. The control group of mice exhibited significant airway hyperreactivity, goblet cell hyperplasia, and peribronchial fibrosis at day 28 after conidia. Although the two lower doses of IL-13-PE had limited therapeutic effects in mice with fungal-induced allergic airway disease, the highest dose of IL-13-PE tested significantly reduced all features of airway disease compared with the control group. Whole lung mRNA expression of IL-4Ralpha and IL-13Ralpha1 was markedly reduced, whereas bronchoalveolar lavage and whole lung levels of IFN-gamma were significantly elevated in mice treated with 200 ng of IL-13-PE compared with the control group. This study demonstrates that a therapy designed to target IL-13-responsive cells in the lung ameliorates established fungal-induced allergic airway disease in mice.

Gene expression profiles for Fc epsilon RI, cytokines and chemokines upon Fc epsilon RI activation in human cultured mast cells derived from peripheral blood

Mast cells have been reported to release not only chemical mediators, but also cytokines upon Fc epsilon receptor I(Fc epsilon RI) cross-linking. Recently, we have established a culture system to derive chymase-rich human mast cells from mononuclear cells in peripheral blood. However, the functional properties of these mast cells have remained unrevealed. In this study, we examined the functions of peripheral blood-derived human cultured mast cells (pHCMCs). pHCMCs expressed functional Fc epsilon RI, and most of them contained tryptase. These pHCMCs sensitized with immunoglobulin E (IgE) and interleukin 4 (IL-4) were activated through cross-linking of Fc epsilon RI. The time-dependent mRNA expression profiles of Fc epsilon RI subunits, cytokines and chemokines in the sensitized pHCMCs upon Fc epsilon RI engagement were examined by reverse transcriptase polymerase chain reaction (RT-PCR). mRNA for most of cytokines and chemokines, which were observed in allergic inflammation, was detected in activated pHCMCs. In addition, gene expression for monocyte chemoattractant protein 3 (MCP-3) in human mast cells, and liver and activation-regulated chemokine (LARC), thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) in mast cells was revealed for the first time in our study. Fc epsilon RI-mediated cytokine and chemokine production at protein level was evaluated using enzyme-linked immunosorbent assay (ELISA). These data suggest that pHCMCs, which are capable of producing a variety of cytokines and chemokines, can be a useful candidate for investigating roles of mast cells as a conductor for allergic inflammation.

Rat mast cell protease-I enhances immunoglobulin E production by mouse B cells stimulated with interleukin-4

Mast cell chymase plays important roles in inflammation and tissue remodeling. Here we show that mast cell chymase also functions as an enhancer of immunoglobulin production. In the culture of murine spleen cells stimulated with lipopolysaccharide and interleukin-4, purified rat chymase (rat mast cell protease-I; RMCP-I), at physiological concentrations, enhanced immunoglobulin E (IgE) and IgG1 syntheses but not IgG3 synthesis. The enhancement was also evident when spleen cells depleted of T cells and macrophages were employed as responding cells. Enzymatic activity of RMCP-I was required to enhance IgE and IgG1, because two inhibitors for chymotryptic enzymes, chymostatin and Y-40613, a novel chymase inhibitor, suppressed the enhanced immunoglobulin production, and phenylmethylsulphonyl fluoride, an irreversible inhibitor for serine proteases, totally abolished the enhancing effect. Furthermore, a specific inhibitor for Zn2+-dependent metalloproteases, GI 129471, could also completely inhibit the production of IgE and IgG1 that was enhanced by RMCP-I, suggesting that a metalloprotease also played an essential role in the immunoglobulin production. Our results together with others show that proteases from mast cell granules have important function not only in the efferent phase but also in the afferent phase of immune responses.

Resting and activation-dependent ion channels in human mast cells

The mechanism of mediator secretion from mast cells in disease is likely to include modulation of ion channel activity. Several distinct Ca(2+), K(+), and Cl(-) conductances have been identified in rodent mast cells, but there are no data on human mast cells. We have used the whole-cell variant of the patch clamp technique to characterize for the first time macroscopic ion currents in purified human lung mast cells and human peripheral blood-derived mast cells at rest and following IgE-dependent activation. The majority of both mast cell types were electrically silent at rest with a resting membrane potential of around 0 mV. Following IgE-dependent activation, >90% of human peripheral blood-derived mast cells responded within 2 min with the development of a Ca(2+)-activated K(+) current exhibiting weak inward rectification, which polarized the cells to around -40 mV and a smaller outwardly rectifying Ca(2+)-independent Cl(-) conductance. Human lung mast cells showed more heterogeneity in their response to anti-IgE, with Ca(2+)-activated K(+) currents and Ca(2+)-independent Cl(-) currents developing in approximately 50% of cells. In both cell types, the K(+) current was blocked reversibly by charybdotoxin, which along with its electrophysiological properties suggests it is carried by a channel similar to the intermediate conductance Ca(2+)-activated K(+) channel. Charybdotoxin did not consistently attenuate histamine or leukotriene C(4) release, indicating that the Ca(2+)-activated K(+) current may enhance, but is not essential for, the release of these mediators.

Development of an allergy test model: activation of human mast cells with potentially allergenic substances

Due to the permanent increase of newly developed and already existing allergies, simple, quick, and reliable test models for detecting potentially allergenic substances are still required. Here, we describe the development of a new in vitro allergy test based on isolated primary mast cells (MC) of non-allergic patients from lung tissue and foreskin specimens, respectively. To establish the specificity of the test model we used primary MC stimulated with immunoglobulin E (IgE), human recombinant stem cell factor (hrSCF), and anti-IgE antibodies to release significant amounts of histamine indicating the ability of MC to cause a hypersensitivity reaction of the immediate type. The general applicability of this test model for detecting allergenic substances could be confirmed by histamine release of primary MC stimulated with sera of patients suffering from house dust allergy, and the corresponding antigen Dermatophagoides pteronyssinus. The results of the present work suggest that this newly developed human in vitro model provides the opportunity of testing substances for their allergenic potential within days and at low costs. This could also be of particular interest for newly produced compounds.

Dynamics of antigen-specific helper T cells at the initiation of airway eosinophilic inflammation

Bronchial asthma is characterized by chronic eosinophilic inflammation of the bronchial mucosa in which Th2 cells play crucial roles. Ovalbumin-reactive Th2 clones were labeled with a fluorescent-probe then infused into unprimed mice to elucidate the dynamics of antigen-specific T cells involved in allergic inflammation. Infiltration of not only labeled antigen-specific T cells, but also unlabeled nonspecific CD4(+) T cells into the bronchial mucosa following inhaled antigen challenge was detectable under confocal microscopy and flow cytometry. Accordingly, labeled T cells in the spleen were decreased, whereas those in hilar lymph nodes were increased upon antigen challenge. Approximately 45% of antigen-specific T cells that migrated into the lungs bore CD25, while another early activation marker, CD69, was expressed on 80% of the migrated T cells. Accordingly, antigen challenge to the mice induced in situ proliferation of antigen-specific T cells as well as bronchial epithelial cells in the lungs. Expression of vascular cell adhesion molecule (VCAM)-1, but not intercellular adhesion molecule (ICAM)-1, on the vascular endothelium in the lungs was enhanced following antigen challenge. Nevertheless, treatment with anti-VCAM-1 antibody, and also anti-ICAM-1 antibody strongly suppressed the accumulation of T cells, suggesting that both VCAM-1 and ICAM-1 are essential for antigen-stimulated T cell mobilization into peripheral tissues. Our current study visualized the kinetics and the mechanism of antigen-specific T cell migration in response to local challenge with a protein antigen.

Gene expression screening of human mast cells and eosinophils using high-density oligonucleotide probe arrays: abundant expression of major basic protein in mast cells

Mast cells (MCs) and eosinophils are thought to play important roles in evoking allergic inflammation. Cell-type--specific gene expression was screened among 12,000 genes in human MCs and eosinophils with the use of high-density oligonucleotide probe arrays. In comparison with other leukocytes, MCs expressed 140 cell-type--specific transcripts, whereas eosinophils expressed only 34. Among the transcripts for expected MC-specific proteins such as tryptase, major basic protein (MBP), which had been thought to be eosinophil specific, was ranked fourth in terms of amounts of increased MC-specific messenger RNA. Mature eosinophils were almost lacking this transcript. MCs obtained from 4 different sources (ie, lung, skin, adult peripheral blood progenitor--derived and cord blood progenitor--derived MCs, and eosinophils) were found to have high protein levels of MBP in their granules with the use of flow cytometric and confocal laser scanning microscopic analyses. The present finding that MCs can produce abundant MBP is crucial because many reports regarding allergic pathogenesis have been based on earlier findings that MBP was almost unique to eosinophils and not produced by MCs. (Blood. 2001;98:1127-1134)