Polyunsaturated fatty acids (PUFAs) exhibit a range of biological effects, many of which are mediated through the formation and actions of their bioactive metabolites. It is well appreciated that dietary PUFA balance affects inflammation and/or allergic diseases, and recent advances in liquid chromatography tandem mass spectrometry (LC-MS/MS)-based mediator lipidomics have revealed a potential link between PUFA metabolism and biological phenotypes. This review presents insights into the emerging roles of eosinophil PUFA metabolism in controlling inflammatory responses and its potential involvement in allergy control.

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Background: Eosinophilic esophagitis (EoE) is related to allergic diseases such as bronchial asthma (BA), atopic dermatitis, and allergic rhinitis. The aim of this study was to examine the eosinophil infiltration in the upper gastrointestinal (GI) tract in patients with BA using esophagogastroduodenoscopy. Methods: Patients with BA who had upper GI tract symptoms were enrolled. Patients who received systemically administered steroids were excluded. Eosinophil infiltrations in the esophagus, stomach, and duodenum were examined with regard to the endoscopic findings and pathological findings of bi- opsy specimens (UMIN000010132). Results: Ninety patients were enrolled from October in 2012 to September in 2014. Thirty-six were male, 54 were female, and the mean age was 57.5 years. Eighty-one (90%) used inhaled corticosteroids. Fourteen patients (15.6%) had reflux esophagitis, 8 of whom had grade A and 6 had grade B. No patient with EoE was observed. One female patient who had marked eosinophil infiltration in the esophagus, stomach, and duodenum was diagnosed as having eosinophilic gastroenteritis, but endoscopy showed only mucosal edema in the antrum. Another female patient who had marked eosinophil infiltration in the esophagus, stomach, and duodenum was diagnosed as having eosinophilic granulomatosis with polyangiitis, and endoscopy showed erosions in the antrum and the duodenum. Three patients had eosinophil infiltration in the stomach, but none of them had severe symptoms. Conclusions: Patients with asthma who had upper gastrointestinal symptoms rarely had eosinophilic gastrointestinal disorders. Biopsy specimens are of high importance in the diagnosis of eosinophilic gastrointestinal disorders even if there is no remarkable endoscopic finding.

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Background: Interleukin (IL)-17A plays a pivotal role in the pathogenesis of rheumatoid arthritis (RA). The expression of IL-17A in synovial mast cells (MCs) in RA and osteoarthritis (OA) has been reported, but the frequencies of IL-17A expression in synovial MCs have varied. The aim of this study was to investigate whether IL-17A expression is upregulated in human synovial MCs in RA and to elucidate the mechanism of IL-17A expression in synovial MCs. Methods: Synovial tissues were obtained from patients with RA or OA undergoing joint replacement surgery, and synovial MCs were enzymatically dispersed. Synovium-derived cultured MCs were generated by culturing synovial cells with stem cell factor. IL-17A expression was investigated using immunofluorescence in synovial tissues. IL-17A mRNA expression and its production from MCs were examined using RT-PCR and ELISA, respectively. Results: The number of IL-17A-positive ⁽⁺⁾ synovial MCs and the percentage of IL-17A⁺ MCs among all the IL-17A⁺ cells from RA patients were not significantly increased compared with those from OA subjects. The synovium-derived cultured MCs spontaneously released small amounts of IL-17A. Neither IgE- nor IgG-dependent stimulation increased IL-17A production from the MCs. IL-33, tumor necrosis factor-a, C5a, lipopolysaccharide or IL-23 plus IL-1β did not affect IL-17A production in MCs. Conclusions: The synovial MCs are not a main source of IL-17A in RA.

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Background: MicroRNAs are non-coding small RNAs that regulate expression of target genes by binding to 3 untranslated regions. In this study, we used bronchial epithelial cells to investigate in vitro the role of the microRNA miR-155 in the expression of chemokines associated with airway inflammation. miR- 155 has previously been reported to regulate allergic inflammation. Methods: BEAS-2B bronchial epithelial cells were cultured and transfected with mimic or inhibitor oli- gonucleotides to overexpress or downregulate miR-155, as confirmed by real-time PCR. Cells were then stimulated with tumor necrosis factor-alpha, interleukin-13 (IL-13), and a double stranded RNA that binds Toll-like receptor 3. Expression and secretion of the chemokines CCL5, CCL11, CCL26, CXCL8, and CXCL10 were then quantified by real-time PCR and ELISA, respectively. Phosphorylation of signal transducer and activator of transcription 6 (STAT6), a target of the IL-13 receptor, was analyzed by ELISA. Results: miR-155 overexpression significantly suppressed IL-13-induced secretion of CCL11 and CCL26. These effects were specific, and were not observed for other chemokines, nor in cells with down- regulated miR-155. miR-155 overexpression also suppressed CCL11 and CCL26 mRNA, but did not affect expression of the IL-13 receptor or phosphorylation of STAT6. Conclusions: miR-155 specifically inhibits IL-13-induced expression of eosinophilic chemokines CCL11 and CCL26 in bronchial epithelial cells, even though the 3'-untranslated region of these genes do not contain a consensus binding site for miR-155.

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Background: Airway accumulation of eosinophils and bronchial hyperresponsiveness (BHR) are prominent features of bronchial asthma, though the contribution of eosinophils to the development of BHR is controversial. Similar to Th2 cell-mediated pathology, Th9 cells, characterized by IL-9-producing activity, have been demonstrated to induce airway eosinophilia and BHR. In this study, we investigated the role of eosinophils in Th9-mediated BHR by employing Th9 cell-transferred murine airway inflammation model. Methods: Ovalbumin (OVA)-specific Th2 and Th9 cells were differentiated from CD4⁺ T cells of DO11.10/ RAG-2^-/- mice in vitro and cytokine-producing activity of those cells was examined. BALB/c mice were adoptively transferred with Th2 or Th9 cells and challenged with OVA. Then, the number of inflammatory cells in bronchoalveolar lavage fluid and bronchial responsiveness to inhaled methacholine were determined. Results: Both in Th2 and Th9 cell-transferred mice, substantial accumulation of eosinophils in the lungs and BHR were induced by challenge with specific antigen. Nevertheless, an essential and dispensable role of eosinophils in Th2- and Th9-mediated BHR, respectively, was demonstrated by employing eosinophildeficient mice. The neutralization of IL-9 as well as deficiency of IL-10 in the donor cells did not affect Th9-mediated BHR. Conclusions: In contrast to Th2-mediated and eosinophil-dependent BHR, Th9 could induce BHR independently from eosinophils and its characteristic cytokines, IL-9 and IL-10.

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Background: Viral infections are the most common cause of asthma exacerbation. Virally infected epithelial cells undergo apoptosis. Although in healthy conditions, apoptosis may have a host-defensive role in limiting virus spread, this process may have a detrimental effect on damaged epithelium in asthma. Toll-like receptors (TLRs) are the receptors for various pathogens, and viruses possess several components that can activate TLR3, TLR4, and TLR7/8. However, as it has not been determined as to which component is responsible for virus-induced epithelial cell apoptosis, we comprehensively analyzed the effects of all TLR ligands on apoptosis. Methods: BEAS-2B cells or primary cultured human bronchial epithelial cells (PBECs) were stimulated by TLR 2, 3, 4, 5, 7/8, and 9 ligands and cell death was analyzed by flow cytometry. Chemokine generations induced by these ligands were also analyzed. Results: The TLR3 ligand polyinosinic-polycytidylic acid (poly I:C) specifically induced chemokine generation and apoptosis, while other TLR ligands including those for TLR5, 7/8, and 9 had no effect. The response to poly I:C had two phases, which included rapid secretion of chemokines and subsequent apoptosis in a later phase. Poly I:C induced apoptosis in a caspase-dependent manner and functionally upregulated the expression of Fas. Conclusions: Previous findings indicating that viruses induced caspase-dependent death and upregulated Fas expression were reproduced by poly I:C, suggesting the central role of dsRNA/TLR3 in virusinduced apoptosis. Since these processes may have detrimental effects on pre-existing epithelial damage, the dsRNA/TLR3 pathway may be potential novel treatment target for virus-induced exacerbation of asthma.

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Background: Psychological stress is one of the major risk factors for asthma exacerbation. Although histamine in the brain acts as an excitatory and inhibitory neurotransmitter associated with psychological stress, the contribution of brain histamine to psychological stress-induced exacerbation of asthma remains unclear. The objective of this study was to investigate the role of histamine receptors in the CNS on stress induced asthma aggravation. Methods: We monitored the numbers of inflammatory cells and interleukin (IL)-13 levels in bronchoalveolar lavage fluid, airway responsiveness to inhaled methacholine, mucus secretion in airway epithelial cells, and antigen-specific IgE contents in sera in a murine model of stress-induced asthma treated with epinastine (an H₁R antagonist), thioperamide (an H_3/4R antagonist), or solvent. Results: All indicators of stress-induced asthma exacerbation were significantly reduced in stressed mice treated with epinastine compared with those treated with solvent, whereas treatment with thioperamide did not reduce the numbers of inflammatory cells in the stressed mice. Conclusions: These results suggest that H₁R, but not H_3/4R, may be involved in stress-induced asthma exacerbations in the central nervous system.

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Background: Epithelial-mesenchymal transition (EMT) is reported to promote airway remodeling in asthmatics, which is the main histological change that causes complex and severe symptoms in asthmatics. However, little is known about whether EMT also plays a role in acute exacerbations of asthma evoked by respiratory tract infections. Methods: A human lung adenocarcinoma line, A549, was incubated with TGF- β1 at 10 ng/ml to induce EMT. Then the cells were stimulated with CpG ODN. Expression of surface and intracellular molecules was analyzed by flow cytometry. IL-6, IL-8 and MCP-1 in the culture supernatant were measured by Cytometric Bead Assay, and the expression of mRNA was quantitated by real-time PCR. CpG ODN uptake was analyzed by flow cytometry. Results: The culture supernatant levels of IL-6, IL-8 and MCP-1 and the expression of mRNA for these cytokines in CpG ODN-stimulated A549 cells that had undergone EMT was significantly higher compared to those that had not. Addition of ODN H154, a TLR9-inhibiting DNA, significantly suppressed the CpG ODN-induced production of those cytokines. However, flow cytometry found the level of TLR9 expression to be slightly lower in A549 cells that had undergone EMT compared to those that had not. On the other hand, CpG ODN uptake was increased in cells that had undergone EMT. Conclusions: EMT induction of A549 cells enhanced CpG ODN uptake and CpG ODN-induced production of IL-6, IL-8 and MCP-1. These results suggest that EMT plays an important role in exacerbation in asthmatics with airway remodeling by enhancing sensitivity to extrinsic pathogens.

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