Lung Epithelial TRPA1 Mediates Lipopolysaccharide-Induced Lung Inflammation in Bronchial Epithelial Cells and Mice

Toll-like receptor (TLR) 4 was originally thought to be the sole pattern recognition receptor for lipopolysaccharide (LPS). Transient receptor potential ankyrin 1 (TRPA1), a Ca2+-permeant channel, has been suggested as a non-TLR receptor membrane-bound sensor of LPS. We recently reported that TRPA1 is expressed in lung epithelial cells (LECs) and mediates lung inflammation induced by cigarette smoke. However, the role of TRPA1 in LPS-induced lung inflammation has not been conclusively defined, and its underlying cellular mechanisms remain unclear. In this study, our in vitro results showed that LPS sequentially produced a cascade of events, including the elevation of intracellular Ca2+, the activation of NADPH oxidase, increase in intracellular reactive oxygen species (ROS), the activation of mitogen-activated protein kinase (MAPK)/nuclear factor-kB (NF-κB) signaling, and the induction of IL-8. The increase in intracellular Ca2+ was inhibited by HC030031 (a TRPA1 antagonist) but was unaffected by TAK-242 (a TLR-4 inhibitor). The activation of NADPH oxidase was prevented by its inhibitor apocynin, EGTA (an extracellular Ca2+ chelator), and HC030031. The increase in intracellular ROS was attenuated by apocynin, N-acetyl-cysteine (NAC, a ROS scavenger), EGTA, and HC030031. The activation of the MAPK/NF-κB signaling was halted by NAC, EGTA, and HC030031. IL-8 induction was suppressed by HC030031 and TRPA1 siRNA, and further reduced by the combination of HC030031 and TAK-242. Our in vivo studies showed that trpa1–/– mice exhibited a reduced level of LPS-induced lung inflammation compared with wild-type mice as evidenced by the alleviations of increases in vascular permeability, inflammatory cell infiltration, inflammatory cytokine levels, oxidative stress, and MAPK signaling activation. Thus, in LECs, LPS may activate TRPA1 resulting in an increase in Ca2+ influx. The increased intracellular Ca2+ leads to NADPH oxidase activation, which causes an increase in intracellular ROS. The intracellular ROS activates the MAPK/NF-κB signaling resulting in IL-8 induction. This mechanism may possibly be at work to induce lung inflammation in mice

Time for a new language for asthma control : Results from REALISE Asia

Acknowledgments: This study was supported and funded by Mundipharma Pte Ltd. Online survey and statistical analysis were performed by Pei-Li Teh, Rachel Howard, Tsin-Li Chua, and Jie Sun of Research Partnership Pte Ltd. Medical writing support was provided by Sen-Kwan Tay of Research2Trials Clinical Solutions Pte Ltd.Peer reviewedPublisher PD

Effectiveness of initiating biologics in severe asthma patients with high steroid exposure

Peer reviewedPostprin

Demographic and Clinical Characteristics of Patients with Severe Asthma in the Asian Pacific Region : data from the International Severe Asthma Registry (ISAR)

Peer reviewe

Characterization of patients in the International Severe Asthma Registry with high steroid exposure who did or did not initiate biologic therapy

Peer reviewedPostprin

Association between T2-related co-morbidities and effectiveness of biologics in severe asthma

Acknowledgments The authors thank Mr. Joash Tan (BSc, Hons), of the Observational and Pragmatic Research Institute (OPRI), and Ms Andrea Lim (BSc, Hons) of the Observational Pragmatic Research Institute (OPRI) for their editorial and formatting assistance that supported the development of this publication. Funding statement: This study was conducted by the Observational and Pragmatic Research Institute (OPRI) Pte Ltd and was partially funded by Optimum Patient Care Global and AstraZeneca Ltd. AstraZeneca UK LimitedPeer reviewe

The proinflammatory actions of mast cell tryptase and agonists of protease activated receptor 2 on the human airway epithelium

The aims of this study have been to investigate the proinflammatory actions of tryptase on airway epithelial cells and to examine the potential role of PAR-2 in airway inflammation.Tryptase was isolated to high purity and was added to epithelial cells. An increase in 3H-thymidine uptake in 16HBE 14o- cells (maximal at 10 mU/ml) was induced by tryptase without stimulating significant cell proliferation; while at higher concentrations (80 mU/ml), tryptase actually inhibited DNA synthesis and cell growth in an apparently non-cytotoxic manner. Within 3 h of adding tryptase, marked increases in expression of mRNA for IL-6, IL-8 and GM-CSF were detected by RT-PCR. This was followed by increased secretion of IL-6 (maximal at 6h), IL-8 and GM-CSF (both maximal at 24 h and 48 h) into culture supernatants. The actions of tryptase were in all cases inhibited by heat inactivation of the enzyme or by addition of the protease inhibitor leupeptin. The peptide SLIGKV, an agonist for protease activated receptor 2 (PAR - 2), induced responses similar to those elicited with tryptase, suggesting that the proinflammatory actions may be mediated through activation of this receptor.Tryptase induced a progressive decrease in transepithelial resistance (TER) across monolayers of 16HBE 14o- cells at 80 mU/ml though at lower concentrations (10 or 20 uU/ml) could actually increase TER. The peptide agonist of PAR-2 SLIGKV and trypsin were also able to induce a decline in TER. Pretreatment of cells with pertussis toxin, a Gi protein inhibitor, abolished the response to SLIGKV, but not that to tryptase, suggesting that processes other than PAR-2 activation may mediate the decline in TER induced by tryptase.Tryptase and other agonists of PAR-2 activation could play key roles in epithelial inflammation in asthma and in other allergic conditions, and these must represent attractive targets for therapeutic intervention.</p

Effects of corticosteroid and neuraminidase inhibitors on survival in patients with respiratory distress induced by influenza virus

Background/Purpose: Neuraminidase inhibitors (NAIs) including oseltamivir and peramivir are used for influenza treatment. A systemic corticosteroid is usually administrated for acute respiratory distress syndrome. The aim of this study was to investigate the effect of a systemic corticosteroid and its interaction with NAIs in patients with influenza infection and respiratory distress. Methods: A retrospective survey of hospitalized patients infected with influenza from January 2012 to May 2014 was conducted in a medical center in Taiwan. Results: Eighty-six patients were hospitalized during the study period. Forty-eight patients had respiratory distress and 39 of them (81.3%, 39/48) were supported by a mechanical ventilator. All patients with respiratory distress received oseltamivir; 60.4% (29/48) and 31.3% (15/48) of them received a corticosteroid and salvage intravenous peramivir, respectively. All-cause mortality was 29.1% (14/48), 20% (3/15), and 31% (9/29) in patients with respiratory distress, patients who received salvage peramivir, and patients who received a systemic corticosteroid, respectively. Salvage peramivir seemed to improve prognosis in patients with H1pdm09 or type B virus infection and respiratory distress (p = 0.05). Early initiating corticosteroid had a worse prognosis than initiation after 72 hours of NAI treatment (p = 0.024). In particular, a systemic corticosteroid seemed to lead to a shorter survival time in patients with chronic lung disease (p = 0.05). Conclusion: Salvage peramivir provided a better prognosis than monotherapy with oseltamivir in patients who were infected with H1pdm09 or type B virus and who developed respiratory distress. A systemic corticosteroid should be administered after initiating NAI therapy, especially in patients with chronic lung disease