Expression of the C-C chemokine receptor CCR3 in human airway epithelial cells

Chemokine-induced eosinophil chemotaxis is mediated primarily through the C-C chemokine receptor, CCR3. We have now detected CCR3 immunoreactivity on epithelial cells in biopsies of patients with asthma and other respiratory diseases. CCR3 mRNA was detected by Northern blot analysis after TNF-alpha stimulation of the human primary bronchial epithelial cells as well as the epithelial cell line, BEAS-2B; IFN-gamma potentiated the TNF-alpha-induced expression. Western blots and flow cytometry confirmed the expression of CCR3 protein. This receptor is functional based on studies demonstrating eotaxin-induced intracellular Ca(2+) flux and tyrosine phosphorylation of cellular proteins. The specificity of this functional response was confirmed by blocking these signaling events with anti-CCR3 mAb (7B11) or pertussis toxin. Furthermore, (125)I-eotaxin binding assay confirmed that CCR3 expressed on epithelial cells have the expected ligand specificity. These studies indicate that airway epithelial cells express CCR3 and suggest that CCR3 ligands may influence epithelial cell functions.

Cutaneous injection of human subjects with macrophage inflammatory protein-1 alpha induces significant recruitment of neutrophils and monocytes

Macrophage inflammatory protein (MIP-1 alpha), a member of the CC chemokine subfamily, has been shown to attract T cells and monocytes in vitro and to be expressed at sites of inflammation. Although the in vitro activities of MIP-1 alpha have been well documented, the in vivo biological activities of MIP-1 alpha in humans have not been studied. To address this, we challenged human subjects by intradermal injection with up to 1000 pmol of MIP-1 alpha and performed biopsies 2, 10, and 24 h later. Although no acute cutaneous or systemic reactions were noted, endothelial cell activation, as indicated by the expression of E-selectin, was observed. In agreement with its in vitro activity, monocyte, lymphocyte, and, to a lesser degree, eosinophil infiltration was observed, peaking at 10-24 h. Surprisingly, in contrast to its reported lack of in vitro neutrophil-stimulating activity, a rapid infiltration of neutrophils was observed in vivo. This neutrophil infiltration occurred as early as 2 h, preceding the appearance of other cells, and peaked at 10 h. Interestingly, we found that neutrophils in whole blood, but not after isolation, expressed CCR1 on their cell surface. This CCR1 was thought to be functional as assessed by neutrophil CD11b up-regulation following whole-blood MIP-1 alpha stimulation. These studies substantiate the biological effects of MIP-1 alpha on monocytes and lymphocytes and uncover the previously unrecognized activity of MIP-1 alpha to induce neutrophil infiltration and endothelial cell activation, underscoring the need to evaluate chemokines in vivo in humans.

Activation of eotaxin gene transcription by NF-kappa B and STAT6 in human airway epithelial cells

The C-C chemokine eotaxin is a potent chemoattractant for eosinophils and probably plays an important role in the pathogenesis of asthma, although the mechanisms of its regulation are not well known. Airway epithelial cells express eotaxin mRNA and protein after stimulation with a variety of cytokines. We focused on the molecular mechanisms of eotaxin gene regulation by TNF-alpha and IL-4 in the airway epithelial cell line, BEAS-2B. Cells were transfected with luciferase reporter plasmids, which contained up to 1363 bp of the eotaxin promoter. Eotaxin promoter activity was increased by TNF-alpha (2.5-fold) and IL-4 (1.5-fold), respectively. The combination of TNF-alpha and IL-4 produced 3.6-fold activation of the eotaxin promoter. The eotaxin promoter contains overlapping consensus binding sites for transcription factors, NF-kappa B and STAT6, which are known to mediate responses to TNF-alpha and IL-4, respectively. Electrophoretic mobility shift assays revealed NF-kappa B binding after TNF-alpha stimulation and STAT6 binding after IL-4 stimulation using a DNA probe derived from the eotaxin promoter. Mutant plasmids were generated to define the roles of these transcription factors in eotaxin promoter activity. TNF-alpha stimulation, but not IL-4 stimulation, was lost in plasmids mutated at the NF-kappa B binding site, whereas IL-4 stimulation, but not TNF-alpha stimulation, was lost in plasmids mutated at the STAT6 binding site. When both sites were mutated, all transcriptional activation was lost. These results imply that TNF-alpha and IL-4 stimulate expression of the eotaxin gene by activating NF-kappa B and STAT6.

Expression of interleukin-16 by human epithelial cells. Inhibition by dexamethasone

Production of chemoattractants by bronchial epithelial cells may contribute to the local accumulation of inflammatory cells in patients with bronchial asthma and other pulmonary diseases. Recently, interleukin (IL)-16 (lymphocyte chemoattractant factor) was reported to be a potent chemotactic stimulus for CD4(+) T lymphocytes and eosinophils, the types of leukocyte found in the proximity of bronchial epithelium in asthmatic individuals. To test the possibility that bronchial epithelial cells produce IL-16, we analyzed RNA and culture supernatants from the human bronchial epithelial cell line BEAS-2B, using reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. BEAS-2B constitutively expressed IL-16 messenger RNA (mRNA) and protein; IL-16 expression was significantly upregulated in a concentration-dependent manner within 24 h by stimulation with histamine, IL-1beta, or tumor necrosis factor (TNF)-alpha whereas interferon-gamma did not significantly increase IL-16. Findings in BEAS-2B cells were confirmed in primary bronchial epithelial cells. Using TA cloning, IL-16 was cloned from BEAS-2B airway epithelial cells. Sequence analysis confirmed its near identity with lymphocyte-derived IL-16. The combination of IL-1beta and TNF-alpha had an additive effect on IL-16 expression. This combination of cytokines also had a priming effect on histamine-induced IL-16 mRNA expression, which was observed within 24 h and which increased to at least 48 h after stimulation. The IL-16 expression induced by histamine and combined cytokines was significantly inhibited by pretreatment with the protein synthesis inhibitor cycloheximide (10 microg/ml). Pretreatment with dexamethasone also significantly suppressed the expression of IL-16, in a concentration-dependent manner. Sputum samples from asthmatic subjects were found to have higher levels of IL-16 than were samples from subjects with other pulmonary inflammatory diseases. These findings suggest that bronchial epithelial cells have the capacity to produce IL-16 after stimulation with histamine, IL-1beta, and TNF-alpha, and raise the possibility that epithelium-derived IL-16 may play a role in recruitment of eosinophils and CD4(+) T lymphocytes in the airways. Downregulation of IL-16 expression by dexamethasone suggests that glucocorticoids may inhibit airway inflammation partly by suppressing the synthesis of inflammatory cytokines including IL-16.

Differential regulation of epithelial-derived C-C chemokine expression by IL-4 and the glucocorticoid budesonide

Airway epithelial cells are a rich source of eosinophil-selective C-C chemokines. We investigated whether cytokines and the topical glucocorticoid budesonide differentially regulate RANTES, monocyte chemoattractant protein-4 (MCP-4), and eotaxin mRNA and protein expression in the human bronchial epithelial cell line BEAS-2B and in primary human bronchial epithelial cells by Northern blot analysis and ELISAs. Eotaxin and MCP-4 mRNA expression induced by TNF-alpha alone or in combination with IFN-gamma was near-maximal after 1 h, peaked at 4 and 8 h, respectively, remained unchanged up to 24 h, and was protein synthesis independent. In contrast, RANTES mRNA was detectable only after 2 h and slowly increased to a peak at 24 h, and was protein synthesis dependent. Induction of eotaxin and MCP-4 mRNA showed a 10- to 100-fold greater sensitivity to TNF-alpha compared with RANTES mRNA. IL-4 and IFN-gamma had selective effects on chemokine expression; IL-4 selectively up-regulated the expression of eotaxin and MCP-4 and potentiated TNF-alpha-induced eotaxin, while IFN-gamma markedly potentiated only the TNF-alpha-induced expression of RANTES. Although budesonide inhibited the expression of chemokine mRNA to a variable extent, it effectively inhibited production of eotaxin and RANTES protein. Budesonide inhibited both RANTES- and eotaxin promoter-driven reporter gene activity. Budesonide also selectively accelerated the decay of eotaxin and MCP-4 mRNA. These results point to IL-4 as a possible mediator by which Th2 cells may induce selective production of C-C chemokines from epithelium and indicate that glucocorticoid inhibit chemokine expression through multiple mechanisms of action.

Chemokines and allergic disease

Understanding the chemokine network has become one of the great challenges for researchers interested in inflammatory mechanisms and inflammation-based diseases. The complexity and diversity of the system provide not only a daunting task for its comprehension but also numerous opportunities for development of new, targeted therapies. It is now certain that chemokines are involved as important mediators of allergic inflammation; the fine details and scope of their roles are now under investigation. Presumably, because of distinct pressures on the immune systems of people living in different geographic regions, genetic variation of ligands, receptors, and regulatory regions in the network have emerged. Establishing the roles of these polymorphisms in determining disease susceptibility or progression among individuals and in distinct ethnic groups will provide a basis for improved understanding and treatment of allergic diseases.

An in vitro comparison of commonly used topical glucocorticoid preparations

BACKGROUND

Glucocorticoids (GC) are potent inhibitors of peripheral blood eosinophil, basophil, and airway epithelial cell function.

OBJECTIVES

We compared in vitro the inhibitory activity of synthetic GC used for topical treatment in asthma and rhinitis on basophil histamine release (HR), eosinophil viability, and expression of vascular cell adhesion molecule-1 (VCAM-1) in the human bronchial epithelial cell line BEAS-2B.

METHODS

Cells were treated for 24 hours with increasing concentrations (range 10(-13) to 10(-6) mol/L) of fluticasone propionate (FP), mometasone furoate (MF), budesonide (BUD), beclomethasone dipropionate (BDP), triamcinolone acetonide (TAA), hydrocortisone (HC), or dimethyl sulfoxide diluent before challenge. HR was measured by a fluorometric assay, viability of purified eosinophils was assessed by erythrosin B dye exclusion, and expression of VCAM-1 was measured by flow cytometry.

RESULTS

GC induced a concentration-dependent inhibition of anti-IgE-induced HR. Maximum inhibition ranged from 59. 7% to 81%, with a rank order of GC potency of FP > MF > BUD > BDP congruent with TAA >> HC. Three-day treatment of eosinophils with GC concentration-dependently inhibited IL-5-induced eosinophil viability, with a rank of potency almost identical to that observed with basophil HR. The rank order of potency of GC for inhibition of the expression of VCAM-1 in BEAS-2B cells was MF congruent with FP >> BUD > TAA > HC congruent with BDP. Inhibitory concentration of 50% values revealed that epithelial cells were the most sensitive and eosinophils were the least sensitive.

CONCLUSIONS

These data, combined with information on pharmacodynamics of these drugs in vivo, may be useful in estimating GC local anti-inflammatory effects.

Production of the novel C-C chemokine MCP-4 by airway cells and comparison of its biological activity to other C-C chemokines

Monocyte chemotactic protein-4 (MCP-4) is a newly identified C-C chemokine with potent eosinophil chemoattractant properties. We describe studies of its biological activity in vitro to induce chemotaxis of peripheral blood eosinophils and to induce histamine release from IL-3-primed peripheral blood basophils. MCP-4 and eotaxin caused a similar rise in eosinophil intracytoplasmic Ca2+ and complete cross-desensitization. MCP-4 also abolished the eosinophil Ca2+ response to MCP-3 and partially desensitized the response to macrophage inflammatory protein-1alpha. MCP-4 activated cell migration via either CCR2b or CCR3 in mouse lymphoma cells transfected with these chemokine receptors. MCP-4 inhibited binding of 125I-eotaxin to eosinophils and CCR3-transfected cells and inhibited 125I-MCP-1 binding to CCR2b-transfectants. MCP-4 mRNA was found in cells collected in bronchoalveolar lavage of asthmatic and nonasthmatic subjects and was prominently expressed in human lung and heart. MCP-4 mRNA was expressed in several human bronchial epithelial cell lines after cytokine stimulation. Pretreatment of BEAS-2B epithelial cells with the glucocorticoid budesonide inhibited MCP-4 mRNA expression. These features make MCP-4 a candidate for playing a role in eosinophil recruitment during allergic respiratory diseases.

Detection of the chemokine RANTES and endothelial adhesion molecules in nasal polyps

BACKGROUND

To better understand the mechanisms of eosinophil recruitment into the upper airways, we examined human nasal polyps for the expression of the chemotactic cytokine RANTES and the endothelial adhesion molecules E-selectin and vascular cell adhesion molecule-1 (VCAM-1).

METHODS

Routine histologic examination and immunostaining with antibodies to RANTES, E-selectin, and VCAM-1 were performed on three types of tissues: nasal polyps, sinus mucosa, or turbinates from patients undergoing other elective procedures (S/T), and nasal biopsy specimens from nonallergic volunteers (NA). To further quantify the expression of endothelial adhesion molecules, some tissue samples were homogenized, and the resulting supernatants were assayed with sandwich ELISAs for VCAM-1 and E-selectin.

RESULTS

Polyp eosinophil counts ranged from 19/mm2 to 1818/mm2 (763 +/- 120/mm2, mean +/- SEM) and were significantly higher than those found in the control tissues (5 +/- 2 in S/T samples and 20 +/- 9 in NA samples, p < 0.002). Immunochemical staining for RANTES was observed in 11 of 14 polyps; intense staining for RANTES (grade 3) was observed in six of 14 polyps. None of nine S/T samples or five NA samples demonstrated grade 3 staining. Staining with anti-RANTES was largely localized to airway and glandular epithelium. There was no significant correlation between counts of eosinophils or the combined total of eosinophils plus mononuclear cells and the intensity of epithelial RANTES staining in all nasal tissues. Staining for VCAM-1, as well as for E-selectin, was detected in 11 of 14 polyps and eight of 13 control tissues. VCAM-1 detected by ELISA in polyp tissues (6.8 +/- 1.3 micrograms/gm) was higher than that found in six S/T samples (1.2 +/- 0.3 micrograms/gm, p < 0.005) and in two NA samples (1.8 +/- 0.02 micrograms/gm, p = 0.08). E-selectin values in polyps (1.4 +/- 0.3 micrograms/gm) were not statistically different from those detected in six S/T samples (0.5 +/- 0.2 microgram/gm) or two NA samples (1.6 +/- 0.4 microgram/gm). Counts of eosinophils and eosinophils plus mononuclear cells displayed a strong correlation with VCAM-1 ELISA values (p < 0.005 and p < 0.004, respectively) but not with VCAM-1 staining. VCAM-1 staining correlated with EG2-positive eosinophils in nasal polyp tissues (p < 0.01). E-selectin staining did not correlate with either neutrophil or eosinophil counts.

CONCLUSIONS

These studies demonstrate that the chemokine RANTES is produced in vivo predominantly to nasal epithelium. Endothelial activation, as indicated by adhesion molecule expression, occurs in human nasal polyp tissues and in control tissues, possibly reflecting the continued antigen exposure of the nasal mucosa. The correlations found in this study suggest that expression of VCAM-1 plays a role in the selective recruitment of eosinophils and mononuclear cells into nasal polyp tissues and that RANTES may be more important in localizing eosinophils to the epithelium.

Contrast media are incomplete secretagogues acting on human basophils and mast cells isolated from heart and lung, but not skin tissue

To investigate the mechanisms of anaphylactoid reactions to radiocontrast media, in vitro mediator release induced by three iodinated contrast agents was examined using peripheral blood basophils and mast cells purified from human lung parenchyma, heart, and skin tissues. Three iodinated contrast agents, sodium and meglumine salts of ioxaglic acid, sodium and meglumine salts of ioxithalamic acid, and ioversol, were incubated with basophils purified from peripheral blood and human mast cells isolated and purified from different anatomical sites. Release of preformed (histamine and tryptase) and de novo synthesized mediators (prostaglandin D2 and leukotriene C4) into the supernatans was determined at various contrast medium concentrations after incubation for 60 min. Ioxaglate (0.2-0.3 M), ioxithalamate (0.3-0.5 M), and to a lesser extent ioversol (0.3-0.5 M) induced histamine release from basophils in a concentration-dependent manner. All three induced the release of preformed mediators (histamine and tryptase) from human lung, but not from skin mast cells. They also induced histamine and tryptase release from human heart mast cells. However, they did not induce the de novo synthesis of leukotriene C1 or prostaglandin D2 from human basophils or any type of mast cell examined. Cross-linking of IgE by anti-IgE induced the release of leukotriene C4 or prostaglandin D2 from human basophils or mast cells. Mannitol, an osmotic stimulus, induced the release of histamine from human basophils, but to a lesser extent from mast cells. These results show that different contrast media can differ in their ability to release mediators from enriched preparations of human basophils and mast cells. The three contrast agents examined act on basophils and mast cells as incomplete secretagogues, causing the release of preformed mediators, but not these novo synthesis of chemical mediators. It may be useful to measure plasma tryptase levels to detect adverse reactions caused by iodinated radiographic contrast materials.

Role of mast cells, basophils and their mediators in adverse reactions to general anesthetics and radiocontrast media

General anesthetics and radiocontrast media (RCM) can cause anaphylactic or anaphylactoid reactions. These are usually underdiagnosed and underreported, but their incidence is apparently rising. Their pathogenesis is complex and not completely understood, but the release of vasoactive mediators from basophils and mast cells plays a central role. The recent development of in vitro techniques to study the release of preformed (histamine and tryptase) and de novo synthesized mediators (PGD2, LTC4, and PAF) from purified basophils and mast cells has made it possible to quantify the mediator-releasing activity of anesthetics such as muscle relaxants, general anesthetics, opioids, and benzodiazepines and RCM on human basophils and mast cells isolated from lung, skin and heart tissues. The majority of general anesthetics and RCM tested induced only the release of preformed mediators (histamine and tryptase), not of the de novo synthesized eicosanoids. There was wide variability in the response of basophils and mast cells from different donors to the same drug or RCM, presumably due to the releasability parameter. Hyperosmolality is probably not the only factor responsible for basophil and mast cell activation by RCM. The in vitro release of histamine induced by anesthetic drugs and RCM was correlated with the release of tryptase. Given the longer half-life of tryptase than histamine in plasma, measurements of plasma tryptase may become a useful diagnostic tool for identifying adverse reactions to anesthetics and RCM.

Human basophil/mast cell releasability. XI. Heterogeneity of the effects of contrast media on mediator release

BACKGROUND

The activation of basophils and mast cells plays a role in the pathogenesis of anaphylactoid reactions occurring during the administration of iodinated radiocontrast media.

METHODS

We compared the effects of three contrast media (CM), Hexabrix (sodium and meglumine salts of ioxaglic acid), Telebrix (sodium and meglumine salts of ioxitalamic acid), and Optiray (ioversol) on the release of preformed (histamine and tryptase) and de novo synthesized (prostaglandin D2 and leukotriene C4) mediators from human basophils and mast cells isolated from lung, skin, and heart tissue. The commercial preparations were evaluated in parallel with the pure substances. Mannitol was used as a positive control inducing histamine release (HR) by hyperosmolar stimulation.

RESULTS

Hexabrix (0.1 to 0.3 mol/L), Telebrix (0.1 to 0.5 mol/L), Optiray (0.2 to 0.5 mol/L), and the corresponding pure substances concentration-dependently induced HR from basophils. A positive correlation was found between CM osmolality and HR from basophils. Mast cells isolated from different anatomic sites responded differently to the three CM. Hexabrix and Optiray induced histamine and tryptase release from human lung mast cells, but not from human skin mast cells. No correlation was found between the osmolality of CM and HR from human lung mast cells. There was a significant correlation between the percent of histamine and tryptase release induced by CM from human lung mast cells. Hexabrix, Telebrix, and Optiray also induced histamine and tryptase release from human heart mast cells. None of the CM induced the de novo synthesis of leukotriene C4 or prostaglandin D2 from basophils or mast cells. The kinetics of HR caused by CM differed according to the drug used and the cell (basophils or human lung mast cells) examined. CM-induced HR from basophils and human lung mast cells was temperature-dependent, partially influenced by extracellular Ca2+ concentrations, and not modified by preincubation of basophils with IL-2 or IL-3.

CONCLUSIONS

These results provide evidence of the heterogeneity of the effects of CM on mediator release from human basophils and mast cells from different anatomic sites. They also suggest that hyperosmolarity may be an important factor in the activation of basophils by CM, but less relevant for mast cells. CM induce only the release of preformed mediators. The measurement of plasma tryptase might be clinically useful for monitoring adverse reactions caused by CM.

Glucocorticosteroid inhibition of cytokine production: relevance to antiallergic actions

We believe that there are the following four classes of glucocorticoid-sensitive cytokines that are involved in cell recruitment: (1) those that activate endothelium nonspecifically; (2) those that activate endothelium specifically; (3) those that activate, prime, and prolong the survival of eosinophils; and (4) those that stimulate movement of cells up into the epithelium. Glucocorticoids inhibit the generation of these cytokines and thereby prevent several different aspects of inflammation, including the activation and recruitment of inflammatory cells (eosinophils, basophils, and lymphocytes) and the release of inflammatory mediators. We believe such pleiotropic actions account for the efficacy and widespread use of glucocorticoids in the treatment of asthma.

Expression of the chemokine RANTES by a human bronchial epithelial cell line. Modulation by cytokines and glucocorticoids

The chemokine RANTES is a potent chemoattractant for eosinophils, lymphocytes, and monocytes, and has been detected recently in the epithelium of human airways mucosa. We have studied, therefore, the expression of RANTES mRNA and protein in the human bronchial epithelial cell line BEAS-2B. Using Northern blot analysis, RANTES mRNA was not detectable in unstimulated BEAS-2B cells. Incubation of cells with TNF-alpha or IFN-gamma induced the expression of RANTES mRNA and protein within 16 h. The combination of TNF-alpha and IFN-gamma displayed a marked synergism in inducing RANTES expression. Pretreatment of cells with the glucocorticoid budesonide (10(-10)-10(-7) M) for 24 h inhibited expression of RANTES mRNA and protein stimulated by either TNF-alpha or TNF-alpha plus IFN-gamma in a concentration- and time-dependent manner. Nonglucocorticoid steroids did not inhibit RANTES mRNA expression. Production of RANTES by epithelium could contribute to the mechanism of selective cellular recruitment occurring in the airways during inflammation, thus playing a relevant role in the pathogenesis of diseases such as asthma, rhinitis, and polyposis. The down-regulation of RANTES production by glucocorticoids in epithelial cells may contribute to the efficacy of these compounds in reducing cellular infiltration and, ultimately, to their anti-inflammatory properties.

Expression of the chemokine RANTES by a human bronchial epithelial cell line. Modulation by cytokines and glucocorticoids

The chemokine RANTES is a potent chemoattractant for eosinophils, lymphocytes, and monocytes, and has been detected recently in the epithelium of human airways mucosa. We have studied, therefore, the expression of RANTES mRNA and protein in the human bronchial epithelial cell line BEAS-2B. Using Northern blot analysis, RANTES mRNA was not detectable in unstimulated BEAS-2B cells. Incubation of cells with TNF-alpha or IFN-gamma induced the expression of RANTES mRNA and protein within 16 h. The combination of TNF-alpha and IFN-gamma displayed a marked synergism in inducing RANTES expression. Pretreatment of cells with the glucocorticoid budesonide (10(-10)-10(-7) M) for 24 h inhibited expression of RANTES mRNA and protein stimulated by either TNF-alpha or TNF-alpha plus IFN-gamma in a concentration- and time-dependent manner. Nonglucocorticoid steroids did not inhibit RANTES mRNA expression. Production of RANTES by epithelium could contribute to the mechanism of selective cellular recruitment occurring in the airways during inflammation, thus playing a relevant role in the pathogenesis of diseases such as asthma, rhinitis, and polyposis. The down-regulation of RANTES production by glucocorticoids in epithelial cells may contribute to the efficacy of these compounds in reducing cellular infiltration and, ultimately, to their anti-inflammatory properties.

Mechanisms of activation of human mast cells and basophils by general anesthetic drugs

A study was performed about the effects of increasing concentrations of muscle relaxants (suxamethonium, d-tubocurarine, vecuronium, and atracurium), hypnotics (propofol, ketamine, and thiopental), opioids (morphine, buprenorphine, and fentanyl), and benzodiazepines (diazepam, flunitrazepam, and midazolam) on the release of preformed (histamine and tryptase) and de novo synthesized (prostaglandin D2: PGD2 and peptide-leukotriene C4: LTC4) chemical mediators from human basophils and mast cells isolated from skin (HSMC), lung parenchyma (HLMC) and heart tissue (HHMC). None of the drugs tested induced the release of histamine or LTC4 from basophils of normal donors. Suxamethonium did not induce mediator release from any type of human mast cell tested. Only the highest concentration of d-tubocurarine used caused histamine release from HSMC and HLMC. Atracurium, more than vecuronium, induced concentration-dependent histamine release from HSMC and HLMC. Propofol induced a concentration-dependent histamine release from HLMC, but not from HHMC. Only the highest concentrations of ketamine and thiopental used caused a significant release of histamine from HLMC. The muscle relaxants and hypnotics examined did not induce any de novo synthesis of PGD2 or LTC4 in mast cells. Morphine only induced histamine and tryptase release from HSMC, but not the de novo synthesis of PGD2. In contrast, buprenorphine caused histamine and tryptase release from HLMC, and not from HSMC, whilst it also induced de novo synthesis of PGD2 and LTC4 in HLMC. Fentanyl did not give any histamine and tryptase release from mast cells. Diazepam and flunitrazepam only induced a small release of histamine from mast cells, whereas midazolam caused the release of histamine from HLMC. The biochemical pathways underlying the release of mediators from human mast cells induced by drugs used during general anaesthesia are different from those underlying the immune release of histamine. From the results obtained with the in vitro model described here, it is clear that new drugs promising for the anesthesiologic arena should be tested in vitro before their potential histamine-releasing activity is experienced in vivo.

Anti-inflammatory effects of glucocorticoids and cyclosporin A on human basophils

Pro-inflammatory and vasoactive mediators released from human basophils and mast cells play a role in several inflammatory and immune disorders. It was recently demonstrated that cyclosporin A (CsA) exerts anti-inflammatory effects by inhibiting the release of preformed and de novo synthesized mediators from human basophils. This study compared the effects of pharmacological concentrations of deflazacort (DFZ) and prednisolone (PRED) on the anti-IgE-mediated release of preformed (histamine) and de novo synthesized (leukotriene C4: [LTC4]) mediators from basophils. Basophils were cultured for 18 hours in the presence of pharmacological concentrations of DFZ (10(-8) to 3 x 10(-6) M). DFZ inhibited the anti-IgE-mediated release of histamine and LTC4 from basophils in a concentration-dependent manner (6-40%), and had a similar efficacy and potency to PRED. The effect of DFZ (10(-8) to 10(-7) M) in combination with CsA on the immunological release of histamine and LTC4 from basophils was also evaluated. An 18-hour incubation of basophils with DFZ (10(-8) M) followed by a short (15-minute) incubation with CsA (30 ng/ml) resulted in an additive inhibition of the release of histamine and LTC4. The additive anti-inflammatory effect of these drugs makes them interesting candidates for future controlled clinical trials in inflammatory diseases in which basophil-derived mediators play a relevant role.

Anti-inflammatory effect of FK-506 on human skin mast cells

FK-506 and the structurally related macrolide rapamycin are high-affinity ligands for a specific binding protein (FK-506 binding protein). We examined the effects of FK-506 and rapamycin on the release of pre-formed (histamine) and de novo synthesized inflammatory mediators (prostaglandin D2) from mast cells isolated from human skin tissue. FK-506 (0.1 to 100 nM) concentration-dependently inhibited (5 to 65%) histamine release from skin mast cells activated by anti-IgE. FK-506 was more potent in skin mast cells than in basophils (IC40 = 2.15 +/- 0.78 nM versus 5.12 +/- 1.34 nM; p < 0.001), whereas the maximal inhibitory effect was higher in basophils than in skin mast cells (88.77 +/- 2.44% versus 67.30 +/- 3.98%; p < 0.01). FK-506 had little or no inhibitory effect on histamine release from skin mast cells challenged with compound A23187 and substance P, respectively, whereas it completely suppressed A23187-induced histamine release from basophils. FK-506 (0.1 to 100 nM) also inhibited (up to 65%) the de novo synthesis of prostaglandin D2 from skin mast cells challenged with anti-IgE. Despite its structural similarity to FK-506, rapamycin (10 to 300 nM) had little or no effect on the release of histamine from skin mast cells induced by anti-IgE, A23187, and substance P. However, rapamycin competitively antagonized the inhibitory effect of FK-506 on anti-IgE-induced histamine release from skin mast cells with a dissociation constant of about 14 nM. These data indicate that FK-506, but not rapamycin, is a potent anti-inflammatory agent acting on skin mast cells presumably by binding to the FK-506 binding protein. It thus appears that binding to the FK-506 binding protein is necessary, but not sufficient, to deliver an inhibitory signal to skin mast cells.

Human basophil/mast cell releasability. IX. Heterogeneity of the effects of opioids on mediator release

Opioids differ in their capacity to cause release of histamine. The effects of increasing concentrations of three opioids (morphine, buprenorphine, and fentanyl) were studied on the release of preformed (histamine and tryptase) and de novo synthesized (prostaglandin D2 [PGD2] and peptide-leukotriene C4 [LTC4]) chemical mediators from human peripheral blood basophils and mast cells isolated from skin tissues or lung parenchyma. Basophils released < 5% of their histamine content and did not synthesize significant amounts of LTC4 when incubated with any of the opioids. Mast cells showed markedly different responses to the three opioids. Morphine (10(-5)-3 x 10(-4) M), in a concentration-dependent manner, induced histamine and tryptase release from skin but not from lung mast cells, up to a maximum of 18.2 +/- 1.9% and 13.0 +/- 4.1 micrograms/10(7) cells, respectively. Morphine did not induce de novo synthesis of PGD2 from skin mast cells. Buprenorphine (10(-6)-10(-4) M), in a concentration-dependent manner, caused histamine and tryptase release from lung but not from skin mast cells, to a maximum of 47.6 +/- 7.2% and 35.1 +/- 13.6 micrograms/10(7) cells, respectively. Buprenorphine also induced de novo synthesis of PGD2 and LTC4 from lung mast cells. Fentanyl (10(-5)-10(-3) M) did not induce histamine and tryptase release or the de novo synthesis of PGD2 or LTC4 from any mast cells. Histamine release caused by buprenorphine from lung mast cells was slow (t1/2 = 11.2 +/- 3.6 min) compared with that induced by morphine from skin mast cells (t1/2 < 1 min, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-inflammatory effect of cyclosporin A on human skin mast cells

We have examined the effects of cyclosporin A (CsA) and cyclosporin H (CsH), which bind with different affinity to cyclophilin, to evaluate the role of this protein in the release of preformed (histamine) and de novo synthesized (prostaglandin D2[PGD2]) mediators of inflammatory reactions from human skin mast cells (HSMC). CsA (2.4-800 nM)-inhibited (5-60%) histamine release from HSMC challenged with anti-IgE. CsA exerted little, if any, inhibitory effect on histamine release from HSMC challenged with compound A23187 and substance P, whereas it completely suppressed A23187-induced histamine release from human basophils. Inhibition of histamine release from HSMC challenged with anti-IgE was extremely rapid and was not abolished by washing (three times) the cells before anti-IgE challenge. CsA (2.4-800 nM) markedly inhibited (25-70%) the de novo synthesis of PGD2 from HSMC challenged with anti-IgE. CsH, which has an extremely low affinity for cyclophilin, had no effect on skin mast-cell mediator release. These data suggest that CsA is a potent anti-inflammatory agent acting on HSMC, presumably by interacting with cyclophilin.

General anaesthetics induce only histamine release selectively from human mast cells

We have examined the in vitro effects of increasing concentrations of propofol (5-70 micrograms ml-1), ketamine (10(-6)-10(-3) mol litre-1) and thiopentone (10(-5)-8 x 10(-4) mol litre-1) on the release of preformed histamine and de novo synthesized mediators (peptide leukotriene C4 (LTC4) or prostaglandin D2 (PGD2] from human basophils and mast cells isolated from lung parenchyma and skin tissue and from heart fragments. Propofol, ketamine and thiopentone failed to induce the release of histamine and de novo synthesis of LTC4 from basophils. Propofol induced histamine release from lung (mean 8.6 (SEM 1.6)%) and skin mast cells (3.8 (1.5)%), but not from heart mast cells. Ketamine caused release of histamine from lung (6.2 (0.9)%) and skin mast cells (2.5 (1.5)%). Thiopentone caused a small amount of histamine release from lung mast cells (3.1 (1.2)%). Propofol, ketamine and thiopentone did not induce de novo synthesis of PGD2 and LTC4 from lung and skin mast cells. These results demonstrate that general anaesthetics induce only histamine release selectively from human mast cells.