IL-10 inhibits cysteinyl leukotriene-induced activation of human monocytes and monocyte-derived dendritic cells

New insights into the mechanisms of the immune microenvironment and immunotherapy in osteosarcoma

Osteosarcoma, a malignant bone tumor primarily affecting adolescents, is highly invasive with a poor prognosis. While surgery and chemotherapy have improved survival for localized cases, pulmonary metastasis significantly reduces survival to approximately 20%, highlighting the need for novel treatments. Immunotherapy, which leverages the immune system to target osteosarcoma cells, shows promise. This review summarizes the biological characteristics of osteosarcoma, mechanisms of pulmonary metastasis, and the tumor immune microenvironment (TME). It involves recent immunotherapy advances, including monoclonal antibodies, tumor vaccines, immune cell therapies, checkpoint inhibitors, and oncolytic viruses, and discusses combining these with standard treatments.

Continuous infusion of resolvin D2 in combination with Angiotensin-II show contrary effects on blood pressure and intracardiac artery remodeling

Specialized pro-resolving mediators (SPMs) are key effectors of resolution of inflammation. This is highly relevant for cardiac and vessel remodeling, where the net inflammatory response contributes to determine disease outcome. Herein, we used a mice model of angiotensin (Ang)-II-induced hypertension to study the effect of the SPM Resolvin D2 (RvD2), on hypertension and cardiac remodeling. By using subcutaneous osmotic minipumps, mice were treated with PBS or Ang-II in combination with or without RvD2 for two weeks. Mice receiving RvD2 gained less blood pressure increase compared to Ang-II alone. Surprisingly, however, examination of intracardiac arteries revealed that RvD2 treatment in combination with Ang-II exacerbated Ang-II-induced fibrosis. Measures of vascular smooth muscle cell dedifferentiation correlated with the level of vascular remodeling, indicating that this dedifferentiation, including increased proliferation and migration, is a contributing factor. RNA sequencing of left ventricle cardiac tissue supported these findings as pathways related to cell proliferation and cell differentiation were upregulated in mice treated with Ang-II in combination with RvD2. Additionally, the RNA sequencing also showed upregulation of pathways related to SPM metabolism. In line with this, Mass spectrometry analysis of lipid mediators showed reduced cardiac levels of the arachidonic acid derived metabolite leukotriene E4 in RvD2 treated mice. Our study suggests that continuous infusion through osmotic minipumps should not be the recommended route of RvD2 administration in future studies.

FLIPR Calcium Mobilization Assays in GPCR Drug Discovery

Intracellular calcium mobilization can be measured using several methods varying in indicator dyes and devices used. In this chapter, we describe the fluorescence-based method (FLIPR Calcium 4 Assay) developed by Molecular Devices for a FlexStation and routinely used in our laboratory for detecting intracellular calcium changes. The assay is designed to study calcium mobilization induced by majority of GPCRs and calcium channels and allows for simultaneous concentration-dependent analysis of several receptor agonists and antagonists, useful in receptor characterization and drug discovery projects.

Immune-regulation and -functions of eicosanoid lipid mediators

Bioactive lipids regulate most physiological processes, from digestion to blood flow and from hemostasis to labor. Lipid mediators are also involved in multiple pathologies including cancer, autoimmunity or asthma. The pathological roles of lipid mediators are based on their intricate involvement in the immune system, which comprises source and target cells of these mediators. Based on their biosynthetic origin, bioactive lipids can be grouped into different classes [e.g. sphingolipids, formed from sphingosine or eicosanoids, formed from arachidonic acid (AA)]. Owing to the complexity of different mediator classes and the prominent immunological roles of eicosanoids, this review will focus solely on the immune-regulation of eicosanoids. Eicosanoids do not only control key immune responses (e.g. chemotaxis, antigen presentation, phagocytosis), but they are also subject to reciprocal control by the immune system. Particularly, key immunoregulatory cytokines such as IL-4 and IFN-γ shape the cellular eicosanoid profile, thus providing efficient feedback regulation between cytokine and eicosanoid networks. For the purpose of this review, I will first provide a short overview of the most important immunological functions of eicosanoids with a focus on prostaglandins (PGs) and leukotrienes (LTs). Second, I will summarize the current knowledge on immunological factors that regulate eicosanoid production during infection and inflammation.

Staphylococcus aureus enterotoxin sensitization involvement and its association with the CysLTR1 variant in different asthma phenotypes

BACKGROUND

Sensitization to Staphylococcus aureus enterotoxin (SE) is a known risk factor for asthma susceptibility and severity. However, how SE sensitization is involved in asthma, particularly nonatopic asthma and/or late-onset asthma, remains uncertain.

OBJECTIVE

To clarify the involvement of SE sensitization in nonatopic and/or late-onset asthma and its association with a polymorphism of the cysteinyl leukotriene receptor 1 gene (CysLTR1), which was examined because CysLT signaling is closely associated with late-onset eosinophilic asthma.

METHODS

We assessed associations between sensitization to SE (A and/or B) and clinical indexes in 224 patients with asthma (mean age, 62.3 years; 171 women) from a cohort of the Kinki Hokuriku Airway Disease Conference, particularly those with nonatopic asthma (not sensitized to common aeroallergens) and/or late-onset asthma. Associations between SE sensitization and CysLTR1 polymorphism (rs2806489), a potential regulatory variant for atopic predisposition in women, were also assessed in a sex-stratified manner.

RESULTS

A total of 105 patients (47%) with asthma were sensitized to SE. Among patients with nonatopic asthma (n = 67) or with late-onset asthma (n = 124), those sensitized to SE had significantly higher serum total IgE and periostin levels than those not sensitized. In nonatopic patients, a rapid decrease in forced expiratory volume in 1 second was associated with SE sensitization. In women with asthma, rs2806489 was associated with sensitization to SEB and age at asthma onset.

CONCLUSION

SE sensitization contributes to T_H2 inflammation in nonatopic and/or late-onset asthma. In women with asthma, the CysLTR1 variant might be associated with sensitization to SEB and age at asthma onset.

Sesamol ameliorates hypotension by modulating cytokines and PPAR-gamma in systemic inflammatory response

Sepsis is one of the major causes of death reported in intensive care units. Acute kidney injury (AKI) and hypotension are important in the pathogenesis and mortality of systemic inflammatory response (SIR). Sesamol delays mortality in sepsis; however, its effects on AKI and hypotension and the role of peroxisome proliferator-activated receptor-ɣ (PPAR-γ) activation have not been established. We investigated the effect of sesamol on SIR in cecal ligation and puncture (CLP)-induced acute kidney injury and lipopolysaccharide (LPS)-induced hypotension in rats. Sesamol was subcutaneously injected 1 h after SIR. Renal function (BUN and CRE) and proinflammatory mediators interleukin (IL)-1β and IL-6 were increased after CLP. Tumor necrosis factor (TNF)-α, IL-1β, IL-10, and nitrite production were significantly increased 6 h after LPS-induced hypotension (mean arterial pressure was significantly decreased). Sesamol significantly inhibited BUN, CRE, IL-1β, IL-6, and nitrite after CLP-induced acute renal injury. In addition, sesamol increased mean arterial pressure and IL-10, inhibited TNF-α and IL-1β, but did not affect nitrite production in LPS-induced hypotension. Sesamol increased PPAR-γ in the leucocytes and peritoneal macrophages in LPS-induced SIR. We conclude that sesamol regulates leucocyte and macrophage PPAR-γ-associated systemic cytokines expression, thereby ameliorates acute kidney injury and hypotension in rats.

Ca2+ mobilization assays in GPCR drug discovery

Intracellular calcium mobilization can be measured using several methods varying in indicator dyes and devices used. In this chapter, we describe the fluorescence-based method (FLIPR Calcium 4 Assay) developed by Molecular Devices for a FlexStation and routinely used in our laboratory for detecting intracellular calcium changes. The assay is designed to study calcium mobilization induced by majority of GPCRs and calcium channels and allows for simultaneous concentration-dependent analysis of several receptor agonists and antagonists, useful in receptor characterization and drug discovery projects.

The fish oil ingredient, docosahexaenoic acid, activates cytosolic phospholipase A₂ via GPR120 receptor to produce prostaglandin E₂ and plays an anti-inflammatory role in macrophages

Docosahexaenoic acid (DHA) is one of the major ingredients of fish oil and has been reported to have anti-inflammatory properties mediated through the GPR120 receptor. Whether cytosolic phospholipase A2 (cPLA2 ) and lipid mediators produced from cPLA2 activation are involved in the anti-inflammatory role of DHA in macrophages has not been reported. We report here that DHA and the GPR120 agonist, GW9508, activate cPLA2 and cyclooxygenase 2 (COX-2), and cause prostaglandin E2 (PGE2) release in a murine macrophage cell line RAW264.7 and in human primary monocyte-derived macrophages. DHA and GW9508 activate cPLA2 via GPR120 receptor, G protein Gαq and scaffold protein β-arrestin 2. Extracellular signal-regulated kinase 1/2 activation is involved in DHA- and GW9508-induced cPLA2 activation, but not p38 mitogen-activated protein kinase. The anti-inflammatory role of DHA and GW9508 is in part via activation of cPLA2 , COX-2 and production of PGE2 as a cPLA2 inhibitor or a COX-2 inhibitor partially reverses the DHA- and GW9508-induced inhibition of lipopolysaccharide-induced interleukin-6 secretion. The cPLA2 product arachidonic acid and PGE2 also play an anti-inflammatory role. This effect of PGE2 is partially through inhibition of the nuclear factor-κB signalling pathway and through the EP4 receptor of PGE2 because an EP4 inhibitor or knock-down of EP4 partially reverses DHA inhibition of lipopolysaccharide-induced interleukin-6 secretion. Hence, DHA has an anti-inflammatory effect partially through induction of PGE2.

Key role of group v secreted phospholipase A2 in Th2 cytokine and dendritic cell-driven airway hyperresponsiveness and remodeling

Background

Previous work has shown that disruption of the gene for group X secreted phospholipase A₂ (sPLA₂-X) markedly diminishes airway hyperresponsiveness and remodeling in a mouse asthma model. With the large number of additional sPLA₂s in the mammalian genome, the involvement of other sPLA₂s in the asthma model is possible – in particular, the group V sPLA₂ (sPLA₂-V) that like sPLA₂-X is highly active at hydrolyzing membranes of mammalian cells.

Methodology and Principal Findings

The allergen-driven asthma phenotype was significantly reduced in sPLA₂-V-deficient mice but to a lesser extent than observed previously in sPLA₂-X-deficient mice. The most striking difference observed between the sPLA₂-V and sPLA₂-X knockouts was the significant impairment of the primary immune response to the allergen ovalbumin (OVA) in the sPLA₂-V^−/− mice. The impairment in eicosanoid generation and dendritic cell activation in sPLA2-V^−/− mice diminishes Th2 cytokine responses in the airways.

Conclusions

This paper illustrates the diverse roles of sPLA₂s in the immunopathogenesis of the asthma phenotype and directs attention to developing specific inhibitors of sPLA₂-V as a potential new therapy to treat asthma and other allergic disorders.

Bisoprolol reverses epinephrine-mediated inhibition of cell emigration through increases in the expression of β-arrestin 2 and CCR7 and PI3K phosphorylation, in dendritic cells loaded with cholesterol

The effect of bisoprolol on dendritic cell (DC) migration was investigated, including the analysis of protein expression, cytokine secretion and activation of the PI3K-pathway. The chemotactic cell numbers in cholesterol-loaded DCs treated with epinephrine were significantly decreased by 26.66±6.29% (6h), 35.67±2.91% (12h) and 29.33±1.09% (24h). This effect was significantly reversed by 46.00±10.65% (6h), 64.25±6.77% (12h) and 55.74±5.51% (24h) when bisoprolol and epinephrine were both present. In cholesterol-loaded DCs, treatment with epinephrine significantly increased AR-β1 protein expression by 56.99±4.87%, but inhibited β-arrestin 2 and CCR7 protein expression by 30.51±4.22% and 25.31±0.04%, respectively. These effects were reversed by bisoprolol by 36.87±4.40%, 41.47±3.95% and 30.14±0.54%, respectively. TNF-α and MMP9 levels were decreased by 68.33±4.00% and 39.57±9.21% in cholesterol-loaded DCs treated with epinephrine. In contrast, when bisoprolol and epinephrine were administered together, the secretion of these proteins was significantly increased by 233.81±37.06 % and 76.66±14.21%, respectively. Treatment with epinephrine decreased PI3K-phosphorylation by 31.88±2.79%, 40.24±5.69% and 30.93±4.66% at 15, 30 and 60min, respectively, whereas the effect of epinephrine on the expression of phosphorylated PI3K was reversed by 49.49±12.12%, 70.93±16.14% and 47.62±6.00%, respectively, when cells were treated with both bisoprolol and epinephrine. Wortmannin inhibited the effects of bisoprolol on PI3K-phosphorylation (38.63±6.12%), the expression of CCR7 (23.4±2.72%), the secretion of TNF-α (69.46±4.48%) and MMP9 (43.15±4.63%), and the number of chemotactic cells (36.84±5.22%). This is the first study to establish a signaling pathway, epinephrine-AR-β1-β-arrestin2-PI3K-MMP9/CCR7, which plays a critical role in the migration of DCs.

Serum IL-10 from systemic lupus erythematosus patients suppresses the differentiation and function of monocyte-derived dendritic cells

The role played by cytokines, other than interferon (IFN)-α, in the differentiation and function of dendritic cells (DCs) in systemic lupus erythematosus (SLE), remains unclear. Serum interleukin-10 (IL-10) levels are generally elevated in SLE patients, which might modulate the differentiation of DCs. In this study, DCs were induced from monocytes either by transendothelial trafficking or by culture with granulocyte-macrophage colony-stimulating factor (GM-CSF) + IL-4 + tumor necrosis factor (TNF)-α. Both systems were used to investigate the effects of elevated serum IL-10 level on DC differentiation in SLE patients. The results showed that monocyte-derived DCs induced by either SLE serum or exogenous IL-10 reduced the expression of human leukocyte antigen (HLA)-DR and CD80, decreased IL-12p40 level, and increased IL-10 level, and exhibited an impaired capacity to stimulate allogenic T-cell proliferation. These results indicate that serum IL-10 may be involved in the pathogenesis of SLE by modulating the differentiation and function of DCs.

microRNA-181a represses ox-LDL-stimulated inflammatory response in dendritic cell by targeting c-Fos

Oxidized LDL (ox-LDL) activates dendritic cells (DCs), thereby initiating inflammation responses in atherosclerosis, yet the modulatory mechanisms remain unclear. MicroRNAs (miRNAs) are important regulators for DC functions. This study evaluated the regulation by miRNAs of the ox-LDL-induced DC immune response. In CD11c⁺ DCs from ApoE-deficient mice with hyperlipidemia, microRNA miR-181a was significantly up-regulated. In cultured bone marrow-derived DCs (BMDCs), ox-LDL promoted DC maturation and up-regulated miR-181a expression. Abundance of miR-181a attenuated ox-LDL-induced CD83 and CD40 expression, inhibited the secretion of interleukin (IL)-6 and TNF-α, and up-regulated IL-10, an important anti-inflammatory cytokine that was inhibited by ox-LDL. Inhibition of the endogenous miR-181a reversed the effects on CD83 and CD40 as well as the effects on IL-6 and TNF-α. The putative target genes of miR-181a were evaluated by gene ontology assessment, and the c-Fos-mediated inflammation pathway was identified. miR-181a targeted the 3′ untranslated region of c-Fos mRNA by luciferase experiments. Thus, abundance of miR-181a reduced c-Fos protein, whereas inhibition of miR-181a increased c-Fos protein in BMDCs. We therefore suggest that miR-181a attenuates ox-LDL-stimulated immune inflammation responses by targeting c-Fos in DCs.

Montelukast abrogates rhabdomyolysis-induced acute renal failure via rectifying detrimental changes in antioxidant profile and systemic cytokines and apoptotic factors production

In addition to antiasthmatic effect, the cysteinyl leukotriene receptor 1 (CysLT₁) antagonist montelukast shows renoprotective effect during ischemia/reperfusion and cyclosporine-induced renal damage. Here, we proposed that montelukast protects against rhabdomyolysis-induced acute renal failure. Compared with saline-treated rats, at 48 h following the induction of rhabdomyolysis using intramuscular glycerol (10 ml 50% glycerol/kg), significant elevations in serum levels of urea, creatinine, phosphate and acute renal tubular necrosis were observed. This was associated with elevations in serum Fas, interleukin-10, tumor necrotic factor-alpha, and transforming growth factor-beta1 and renal malondialdehyde and nitrite and detrimental reductions in renal catalase and superoxide dismutase activities. The effects of rhabdomyolysis on renal functional, biochemical and structural integrity and the associated changes in cytokines and Fas levels were abolished upon concurrent administration of montelukast (10 mg/kg i.p.) for 3 days (1 day before and 2 days after induction of rhabdomyolysis). Alternatively, administration of the anti-oxidant, α-tocopherol (400 mg/kg i.m.) for 3 days, succeeded in alleviating renal oxidative stress, but had no significant effect on the circulating levels of most cytokines and partially restored kidney functional and structural damage. Serum level of interleukin-6 was not altered by rhabdomyolysis but showed significant elevations in rats treated with montelukast or α-tocopherol. Collectively, motelukast abrogated functional and structural renal damage induced by rhabdomyolysis via ameliorating renal oxidative stress and modulation of systemic cytokines and apoptotic factors production. The results of this work are expected to open new avenues for early prevention of rhabdomyolysis-induced acute renal failure using selective CysLT₁ antagonists such as montelukast.

International Union of Basic and Clinical Pharmacology. LXXXIV: leukotriene receptor nomenclature, distribution, and pathophysiological functions

The seven-transmembrane G protein-coupled receptors activated by leukotrienes are divided into two subclasses based on their ligand specificity for either leukotriene B(4) or the cysteinyl leukotrienes (LTC(4), LTD(4), and LTE(4)). These receptors have been designated BLT and CysLT receptors, respectively, and a subdivision into BLT(1) and BLT(2) receptors and CysLT(1) and CysLT(2) receptors has been established. However, recent findings have also indicated the existence of putative additional leukotriene receptor subtypes. Furthermore, other ligands interact with the leukotriene receptors. Finally, leukotrienes may also activate other receptor classes, such as purinergic receptors. The aim of this review is to provide an update on the pharmacology, expression patterns, and pathophysiological roles of the leukotriene receptors as well as the therapeutic developments in this area of research.

2-Polyunsaturated acyl lysophosphatidylethanolamine attenuates inflammatory response in zymosan A-induced peritonitis in mice

In the present study, the anti-inflammatory action of lysophosphatidylethanolamine (lysoPtdEtn), orally administered, in zymosan A-induced peritonitis was examined. Oral administration of 2-DHA-lysoPtdEtn (ED(50), ~111 μg/kg) or 2-ARA-lysoPtdEtn (ED(50), 221 μg/kg) was found to inhibit the plasma leakage in mice treated with zymosan A. In support of this, 2-polyunsaturated acyl-lysoPtdEtn diminished the formation of LTC(4), a lipid mediator responsible for vascular permeability. Next, 2-DHA-lysoPtdEtn (ED(50), 110 μg/kg) or 2-ARA-lysoPtdEtn (ED(50), 123 μg/kg) effectively inhibited the leukocyte extravasation into the peritoneum. Consistent with this, each polyunsaturated-lysoPtdEtn diminished the formation of LTB(4) and 12-HETE, potent chemotactic factors. Additionally, the level of pro-inflammatory mediator (IL-1 β, IL-6, TNF-α or NO) was lowered remarkably in contrast to the augmentation of anti-inflammatory interleukin IL-10. Furthermore, 2-(15-HETE)-lysoPtdEtn and 2-(17-HDHE)-lysoPtdEtn, 15-lipoxygenation product of 2-ARA-lysoPtdEtn and 2-DHA-lysoPtdEtn, respectively, were more potent than corresponding lysoPtdEtn, suggesting the action of 2-acyl-lysoPtdEtn might be expressed through 15-lipoxygenation. In support of this, the formation of 15-HETE and LXA(4) was upgraded in accordance with an increasing dose of 2-ARA-lysoPtdEtn. Separately, anti-inflammatory actions, 2-polyunsaturated acyl-lysoPtdEtns also drastically diminished leukocyte infiltration in a later phase of zymosan A-induced peritonitis, indicating that these lipids also possess pro-resolving activity. Taken together, it is suggested that polyunsaturated lysoPtdEtns and their lipoxygenation derivatives, could be classified as potent anti-inflammatory lipids.

Montelukast treatment may alter the early efficacy of immunotherapy in children with asthma

BACKGROUND

Allergen-specific immunotherapy (SIT) is the only available potentially curative approach in the management of allergic diseases. Therapies that boost regulatory T cell induction during SIT might further enhance its effectiveness.

OBJECTIVE

The purpose of this study was to assess the effect of montelukast treatment on early clinical and immunologic effects of allergen-specific immunotherapy in children with asthma.

METHODS

It was a randomized, double-blind, placebo-controlled trial conducted in 36 children with asthma and allergy to house dust mites who required from 400 to 800 microg of inhaled budesonide per day during the 7-month run-in period. Patients were randomly allocated to receive 5 mg montelukast daily (n = 18) or placebo (n = 18) as an addition to inhaled corticosteroid (ICS) treatment during the 3-month build-up phase of SIT, when modification of ICS doses was not allowed. During the 7 months of the maintenance phase of SIT, ICS doses were adjusted to control the asthma symptoms.

RESULTS

After 12 months of SIT, a reduction of the median daily ICS dose, necessary to control asthma symptoms, was 16.7% grater in patients from the placebo group than in patients from the montelukast group. Intervention with montelukast significantly impaired the induction of regulatory T lymphocytes. During the build-up phase of SIT, patients in the placebo group frequently experienced an increase in asthma symptoms leading to exclusions from the per protocol population.

CONCLUSION

Our study failed to show a beneficial effect of montelukast on SIT. In fact, quite the opposite occurred: compared with placebo, montelukast intervention led to less effectiveness of SIT.

Dendritic cells and their role in atherogenesis

Dendritic cells (DCs) are the most potent professional antigen-presenting cells with the unique ability of primary immune response initiation. DCs originate from bone marrow progenitors, which circulate in the peripheral blood and subsequently penetrate peripheral tissues, where they give rise to immature DCs. In peripheral tissues, DCs continuously monitor the microenvironment and, when the cells encounter 'danger' signals, DCs undergo differentiation and maturation. Maturing DCs usually migrate to lymphatic tissues, where they form contacts with T cells to initiate a primary immune response. DCs were identified in arteries in 1995 and since then, further knowledge has been gained about the peculiarities of vascular-associated DCs and their role in atherosclerosis. Immune reactions toward modified lipoproteins and other factors ignited by resident vascular DCs as well as by newly arrived DCs, which originate from blood monocytes, are believed to destabilize arterial homeostasis from very earlier stages of atherogenesis. There is a remarkable heterogeneity of DCs in atherosclerotic lesions. Some DCs mature and become capable of forming clusters with T cells directly within the arterial wall. The predictive value of the numbers of circulating DC precursors in coronary artery disease and in atherosclerosis has been assessed, and it has been shown that DCs have a role in plaque destabilization. Over recent decades, DCs have proven to be a valuable instrument in immunotherapy approaches against cancer and various autoimmune diseases, and this explains the demand that the accumulated knowledge be applied to the field of atherosclerosis immunotherapy.

Concentration-dependent noncysteinyl leukotriene type 1 receptor-mediated inhibitory activity of leukotriene receptor antagonists

The use of cysteinyl leukotriene receptor antagonists (LTRAs) for asthma therapy has been associated with a significant degree of interpatient variability in response to treatment. Some of that variability may be attributable to noncysteinyl leukotriene type 1 receptor (CysLT(1))-mediated inhibitory mechanisms that have been demonstrated for this group of drugs. We used a model of CysLT(1) signaling in human monocytes to characterize CysLT(1)-dependent and -independent anti-inflammatory activity of two chemically different, clinically relevant LTRAs (montelukast and zafirlukast). Using receptor-desensitization experiments in monocytes and CysLT(1)-transfected HEK293 cells and IL-10- and CysLT(1) small interfering RNA-induced downregulation of CysLT(1) expression, we showed that reported CysLT(1) agonists leukotriene D(4) and UDP signal through calcium mobilization, acting on separate receptors, and that both pathways were inhibited by montelukast and zafirlukast. However, 3-log greater concentrations of LTRAs were required for the inhibition of UDP-induced signaling. In monocytes, UDP, but not leukotriene D(4), induced IL-8 production that was significantly inhibited by both drugs at micromolar concentrations. At low micromolar concentrations, both LTRAs also inhibited calcium ionophore-induced leukotriene (leukotriene B(4) and leukotriene C(4)) production, indicating 5-lipoxygenase inhibitory activities. We report herein that montelukast and zafirlukast, acting in a concentration-dependent manner, can inhibit non-CysLT(1)-mediated proinflammatory reactions, suggesting activities potentially relevant for interpatient variability in response to treatment. Higher doses of currently known LTRAs or new compounds derived from this class of drugs may represent a new strategy for finding more efficient therapy for bronchial asthma.

Cysteinyl-leukotriene receptor type 1 expression and function is down-regulated during monocyte-derived dendritic cell maturation with zymosan: involvement of IL-10 and prostaglandins

TLRs sense microbial products and initiate adaptive immune responses by activating dendritic cells (DCs). DCs have been shown to produce leukotrienes and, conversely, leukotrienes are known to modulate several DC functions. In this study, we examined the modulation of expression and function of cysteinyl-leukotriene receptor type 1 (CysLT1) on human monocyte-derived DCs during their differentiation and subsequent maturation with zymosan, a TLR2 agonist. Maturation of DCs with zymosan reduced CysLT1 mRNA levels and protein expression in a time-dependent fashion and was associated with a diminution of functional responsiveness to leukotriene D(4) as assessed by intracellular calcium mobilization, CCL2 and CCL3 production, and chemotaxis. The effect of zymosan was mediated by both TLR2 and dectin-1 activation. Zymosan also induced a rapid expression of cyclooxygenase-2 and the production of PGE(2) and IL-10. Addition of an anti-IL-10 neutralizing Ab or inhibitors of cyclooxygenase greatly reduced the ability of zymosan to down-regulate CysLT1 expression. Down-regulation of CysLT1 expression by zymosan could be reproduced by a combination of IL-10 and PGE(2), and was dependent on MAPK activation. Taken together, our findings indicate that zymosan down-regulates CysLT1 expression in DCs with consequently reduced functional responsiveness of the cells to leukotriene D(4) stimulation. This effect is partially dependent on an endogenous production of PGs and IL-10 by DCs.

Potential therapy of Fc-antigen combination-encoding DNA vaccination in mouse allergic airway inflammation

Vaccination with allergen-encoding DNA has been proposed as having potential for allergen-specific immunotherapy. In this study, we examine the therapeutic effect of allergen-encoding DNA vaccination directly to dendritic cells (DCs) on allergen-induced allergic airway inflammation in a mouse model and explore potential mechanism. Ovalbumin (OVA)-sensitized and challenged mice were immunized with DNA vaccine and received bronchoalveolar lavage (BAL) 1 day after the last challenge, to measure BAL levels of interleukin (IL)-4, IL-5, interferon (IFN)-gamma and differential cell count. Pulmonary DCs and Spleen DCs were purified and sorted according to the expression of CD(11c) (+)CD(80) (+) and CD(11c) (+)CD(86) (+) co-stimulatory molecules. Our data demonstrated that DNA vaccine therapy with OVA-Fc-pcDNA(3.1) significantly prevented OVA-increased levels of IL-4, IL-5 and the percentage of eosinophils and OVA-decreased level of IFN-gamma. OVA-Fc-pcDNA(3.1)-treated mice had less severity of airway inflammation, and lower expression of CD(11c) (+)CD(80) (+) and CD(11c) (+)CD(86) (+) on pulmonary DCs, as compared with animals with OVA-pcDNA(3.1,) pcDNA(3.1) and OVA respectively. DNA vaccine encoding both Fc and OVA was shown to be more effective than DNA vaccine encoding OVA alone. Our data indicate that Fc-antigen combination-encoding DNA vaccination has better preventive effects on antigen-induced airway inflammation by regulating DCs, and may be a new alternative therapy for asthma.