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Cysteinyl leukotrienes (CysLTs), a group of inflammatory lipid mediators, are found elevated in obese-asthmatic patients. Leukotriene D4 (LTD4), a representative CysLT, is implicated in promoting lung inflammation and remodelling in allergic asthma, but its role in non-allergic asthma, especially in obese-asthmatic patients, is not known. Here, using primary human small airway epithelial cells (SAECs) we have investigated the mechanism of LTD4-induced inflammation and remodelling and assessed high proneness of obese mice to develop asthma upon challenge with allergen ovalbumin (OVA). Primary human small airway epithelial cells (SAECs) were stimulated with different concentrations of LTD4 for different time intervals and various inflammatory markers were measured through cytokine array, membrane-based ELISA and Western blotting. An air–liquid interface (ALI) model of SAECs was used to study the effects of LTD4-induced remodelling in SAECs using Western blotting, H&E staining and PAS staining. Further, OVA-based murine model was used to examine the propensity of high-fat diet (HFD)-fed obese mice to develop asthma symptoms by studying the infiltration of inflammatory cells (assessed by bronchioalveolar lavage (BAL) cytology) and airway remodelling (assessed by histopathology) upon allergen exposure. The human primary small airway epithelial cells (SAECs) treated with LTD4 showed significant alterations in the levels of inflammatory markers such as GM-CSF, TNF-α, IL-1β, EGF and eotaxin in dose- and time-dependent manner. Further, LTD4 enhanced the activation of inflammasomes as evidenced by increased levels of NALP3, cleaved caspase-1 and IL-1β. LTD4 also enhanced inflammation by increasing the expression of COX-2 in SAECs. The airway remodelling markers Vimentin and Muc5AC were found elevated in ALI culture of SAECs when stimulated with LTD4, as it also increased TGF-β levels and activation of Smad2/3 phosphorylation in SAECs. Last, sensitization and challenge of HFD-fed obese mice with OVA showed increased infiltration of inflammatory cells in BAL and enhanced levels of remodeling phenotypes like loss of cilia, mucus cell metaplasia and collagen deposition in mice lung tissues. The results suggest that LTD4 could induce inflammatory response in human airway epithelial cell by activating NALP3 inflammasome. LTD4 could further promote airway epithelial cells’ remodelling through TGF-β/smad2/3-mediated pathway. Our in vivo results suggested that obesity predisposed the OVA challenged mice to develop lung inflammation and remodelling akin to asthma-like phenotypes during obesity.

Cysteinyl leukotrienes (CysLTs), a group of inflammatory lipid mediators, are found elevated in obese-asthmatic patients. Leukotriene DPrimary human small airway epithelial cells (SAECs) were stimulated with different concentrations of LTDThe human primary small airway epithelial cells (SAECs) treated with LTDThe results suggest that LTD

Background Cysteinyl leukotrienes (CysLTs), the potent lipid inflammatory mediators, are elevated in many pathological conditions and implicated in various inflammatory diseases including asthma, however their role in airway epithelial cells modulation is not clearly understood. We have investigated the effects of a CysLT, Leukotriene D4 (LTD4) on human airway epithelial cells, and assessed its role and mode of action in these cells. Methodology Human small airway epithelial cells (SAECs) and A549 cells were incubated with different concentrations of LTD4 for different time intervals. Subsequently trypan blue dye exclusion assay, MTT assay, Western blotting, RT-PCR and immunofluorescence experiments were performed to examine the effects of LTD4 on proliferation and related molecular changes in the airway epithelial cells. Results The treatment of human airway epithelial cells with LTD4 resulted in a significant increase in cell proliferation and modulation in the expression of receptors, CysLT1R and CysLT2R in SAECs as well as A549 cells. In both types of cells, LTD4 increased the expression levels of PCNA and c-myc, and trans-activated EGF receptor and increased the activation of ERK1/2. When treated along with epidermal growth factor (EGF), LTD4 showed a marginal additive effect in ERK1/2 and EGFR phosphorylation compared to LTD4 alone in both types of airway epithelial cells. Conclusion In conclusion, these results suggest that sustained presence of lipid inflammatory mediator LTD4 could induce human airway epithelial cell proliferation through ERK1/2 phosphorylation, either directly via CysLT1 receptor or by transactivating EGFR.

Cysteinyl leukotrienes (CysLTs), the potent lipid inflammatory mediators, are elevated in many pathological conditions and implicated in various inflammatory diseases including asthma, however their role in airway epithelial cells modulation is not clearly understood. We have investigated the effects of a CysLT, Leukotriene DHuman small airway epithelial cells (SAECs) and A549 cells were incubated with different concentrations of LTDThe treatment of human airway epithelial cells with LTDIn conclusion, these results suggest that sustained presence of lipid inflammatory mediator LTD