Gheware, A. P. | bioRxiv Science

bioRxiv2020

Docosahexaenoic acid (DHA), a nutritional supplement, modulates steroid insensitivity in asthma

Asthmatics with poor steroid responsiveness are now found to use health services at higher frequency and contribute to socio-economic burden disproportionately. We have previously shown that a ω-6 fatty acid metabolite leads to a severe and steroid insensitive asthma-like condition in mice. Here, we investigated the role of retinoid-x-receptor gamma (RXRγ) and Docosahexaenoic acid (DHA), a ω3 fatty acid rexinoid ligand of RXR, on the features of steroid insensitivity in asthmatic condition. RXRγ was found to be reduced in the lungs of human asthmatics and mice with steroid insensitive allergic airway inflammation. RXRγ knockdown in naïve mice led to spontaneous asthma like features whereas RXRγ knockdown in allergic mice led to steroid insensitive asthma features. We observed while RXRγ binds to the glucocorticoid receptor (GR) gene and regulates its transcription, DHA increases the GRα expression in human bronchial epithelial cells and reverses the steroid insensitive features in mice with allergic airway inflammation. Docosahexaenoic acid (DHA), a ligand of RXR, was reduced in the sera of steroid-insensitive asthmatics. We conclude that DHA may prove to be a promising steroid sensitizing agent for the treatment of steroid insensitive asthmatics.Summary The molecular regulation of glucocorticoid receptor by retinoid-x-receptor gamma (RXRgama) has an implication in steroid insensitive asthma as we found that Docosahexaenoic acid (DHA), a nutritional supplement and natural ligand of RXRgamma, improves steroid sensitivity in steroid insensitive mice model of asthma and DHA levels are found to be low in steroid insensitive asthmatic patients.Competing Interest StatementThe authors have declared no competing interest.Abbreviations usedAAIAllergic airway inflammationAHRAirway hyper-responsivenessATRAAll-trans retinoic acidAUArbitrary unitsBALBronchoalveolar lavageBEAS-2BHuman bronchial epithelial cellsCECockroach allergen extractChIPChromatin Immunoprecipitation9CRA9-cis retinoic acidDEXDexamethasoneDHADocosahexaenoic acidDMSODimethyl sulfoxideELISAEnzyme-linked immunosorbent assayGAPDHGlyceraldehyde 3-phosphate dehydrogenaseGLucGaussia luciferaseGRαGlucocorticoid receptor alphaGREGlucocorticoid receptor elementH & EHaematoxylin and eosinIFNγInterferon gammaIgEImmunoglobulinE ILInterleukinKCKeratinocyte chemoattractant15-LOX15-lipoxygenaseMCF-7Human breast adenocarcinoma cell lineMCP1-αMonocyte chemoattractant protein1-αNF-κBNuclear Factor kappa-light-chain-enhancer of activated B cellsO.EOverexpressionOVAOvalbuminp38-MAPKp38 mitogen-activated protein kinasePBSPhosphate buffered salineRARRetinoic acid receptorPDTCPyrrolidinedithiocarbamateRXRERexinoid receptor elementRXRγRetinoid-x-receptor gamma13-S-HODE13-hydroxyoctadecadienoic acidSEMStandard error meansiRNASmall interfering RNASTAT-6Signal transducer and activator of transcription 6ThT helperVEHVehicleView Full Text

immunology↗

bioRxiv2020

Adhatoda Vasica ameliorates cellular hypoxia dependent mitochondrial dysfunction in acute and severe asthmatic mice.

Severe asthma is a chronic airway disease that exhibits poor response to conventional asthma therapies. Growing evidence suggests that elevated hypoxia increases the severity of asthmatic inflammation among patients and in model systems. In this study, we elucidate the therapeutic effects and mechanistic basis of Adhatoda Vasica (AV) aqueous extract on mouse models of acute allergic as well as severe asthma subtypes at physiological, histopathological, and molecular levels. Oral administration of AV extract attenuates the increased airway resistance and inflammation in acute allergic asthmatic mice and alleviates the molecular signatures of steroid (dexamethasone) resistance like IL-17A, KC, and HIF-1 (hypoxia inducible factor-1alpha) in severe asthmatic mice. AV inhibits HIF-1 levels through restoration of expression of its negative regulator-PHD2 (prolyl hydroxylase domain-2). Alleviation of hypoxic response mediated by AV is further confirmed in the acute and severe asthma model. AV reverses cellular hypoxia-induced mitochondrial dysfunction in human bronchial epithelial cells - evident from bioenergetic profiles and morphological analysis of mitochondria. In silico docking of AV constituents reveal higher negative binding affinity for C and O-glycosides for HIF-1, IL-6, Janus kinase 1/3, TNF- and TGF-{beta}-key players of hypoxia-inflammation. This study for the first time provides a molecular basis of action and effect of AV whole extract that is widely used in Ayurveda practice for diverse respiratory ailments. Further, through its effect on hypoxia-induced mitochondrial dysfunction, the study highlights its potential to treat severe steroid-resistant asthma. Significance StatementSevere asthma is a global health concern with a large fraction unresponsive to current treatment modalities involving corticosteroids. Recent findings suggest that elevated hypoxia has a critical role in severity of asthma. Here, we report therapeutic treatment with aqueous extract of Adhatoda Vasica (AV), an ayurvedic medicine, attenuates sever steroid insensitive asthmatic features in mice. The observed effects of AV are through inhibition of hypoxic response, both in vivo and in vitro. AV also reverses mitochondrial dysfunction, a key consequence associated with hypoxia, and asthma. This study highlights the translational potential of AV for the treatment of severe asthma and provides opportunities for its usage in other disease conditions where hypoxia is pertinent.

immunology↗