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IL-13 desensitizes ?2-adrenergic receptors in human airway epithelial cells through a 15-lipoxygenase/G protein receptor kinase 2 mechanism.

ABSTRACT: BACKGROUND:?2-Adrenergic receptor (?2AR) agonists are critical treatments for asthma. However, receptor desensitization can lead to loss of therapeutic effects. Although desensitization to repeated use of ?2-agonists is well studied, type 2 inflammation could also affect ?2AR function. OBJECTIVE:We sought to evaluate the effect of the type 2 cytokine IL-13 on ?2AR desensitization in human airway epithelial cells (HAECs) and determine whether 15-lipoxygenase-1 (15LO1) binding with phosphatidylethanolamine-binding protein 1 (PEBP1) contributes to desensitization through release of G protein receptor kinase 2 (GRK2). METHODS:HAECs in air-liquid interface culture with or without IL-13 (48 hours) or isoproterenol hydrochloride (ISO; 30 minutes) pretreatment were stimulated with ISO (10 minutes). Cyclic adenosine 3, 5-monophosphate (cAMP) levels were measured using ELISA, and ?2AR and GRK2 phosphorylation was measured using Western blotting. Short interfering RNA was used for 15LO1 knockdown. Interactions of GRK2, PEBP1, and 15LO1 were detected by means of immunoprecipitation/Western blotting and immunofluorescence. HAECs and airway tissue from control subjects and asthmatic patients were evaluated for I5LO1, PEBP1, and GRK2. RESULTS:Pretreatment with ISO or IL-13 decreased ISO-induced cAMP generation compared with ISO for 10 minutes alone paralleled by increases in ?2AR and GRK2 phosphorylation. GRK2 associated with PEBP1 after 10 minutes of ISO in association with low phosphorylated GRK2 (pGRK2) levels. In contrast, in the presence of IL-13 plus ISO (10 minutes), binding of GRK2 to PEBP1 decreased, whereas 15LO1 binding and pGRK2 levels increased. 15LO1 knockdown restored ISO-induced cAMP generation. These findings were recapitulated in freshly brushed HAECs from cells and tissue of asthmatic patients. CONCLUSION:IL-13 treatment of HAECs leads to ?2AR desensitization, which involves 15LO1/PEBP1 interactions to free GRK2, and allows it to phosphorylate (and desensitize) ?2ARs, suggesting that the beneficial effects of ?2-agonists could be blunted in patients with type 2 associated asthma.

SUBMITTER: Albano GD

PROVIDER: S-EPMC4426258 | biostudies-literature | 2015 May

REPOSITORIES: biostudies-literature

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IL-13 desensitizes β2-adrenergic receptors in human airway epithelial cells through a 15-lipoxygenase/G protein receptor kinase 2 mechanism.

Albano Giusy D GD Zhao Jinming J Etling Emily B EB Park Seo Young SY Hu Haizhen H Trudeau John B JB Profita Mirella M Wenzel Sally E SE

The Journal of allergy and clinical immunology 20150324 5

<h4>Background</h4>β2-Adrenergic receptor (β2AR) agonists are critical treatments for asthma. However, receptor desensitization can lead to loss of therapeutic effects. Although desensitization to repeated use of β2-agonists is well studied, type 2 inflammation could also affect β2AR function.<h4>Objective</h4>We sought to evaluate the effect of the type 2 cytokine IL-13 on β2AR desensitization in human airway epithelial cells (HAECs) and determine whether 15-lipoxygenase-1 (15LO1) binding with ...[more]

PMID: 25819984

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Project description:BackgroundImpaired airway mucosal immunity can contribute to increased respiratory tract infections in asthmatic patients, but the involved molecular mechanisms have not been fully clarified. Airway epithelial cells serve as the first line of respiratory mucosal defense to eliminate inhaled pathogens through various mechanisms, including Toll-like receptor (TLR) pathways. Our previous studies suggest that impaired TLR2 function in T(H)2 cytokine-exposed airways might decrease immune responses to pathogens and subsequently exacerbate allergic inflammation. IL-1 receptor-associated kinase M (IRAK-M) negatively regulates TLR signaling. However, IRAK-M expression in airway epithelium from asthmatic patients and its functions under a T(H)2 cytokine milieu remain unclear.ObjectivesWe sought to evaluate the role of IRAK-M in IL-13-inhibited TLR2 signaling in human airway epithelial cells.MethodsWe examined IRAK-M protein expression in epithelia from asthmatic patients versus that in normal airway epithelia. Moreover, IRAK-M regulation and function in modulating innate immunity (eg, TLR2 signaling) were investigated in cultured human airway epithelial cells with or without IL-13 stimulation.ResultsIRAK-M protein levels were increased in asthmatic airway epithelium. Furthermore, in primary human airway epithelial cells, IL-13 consistently upregulated IRAK-M expression, largely through activation of phosphoinositide 3-kinase pathway. Specifically, phosphoinositide 3-kinase activation led to c-Jun binding to human IRAK-M gene promoter and IRAK-M upregulation. Functionally, IL-13-induced IRAK-M suppressed airway epithelial TLR2 signaling activation (eg, TLR2 and human ?-defensin 2), partly through inhibiting activation of nuclear factor ?B.ConclusionsOur data indicate that epithelial IRAK-M overexpression in T(H)2 cytokine-exposed airways inhibits TLR2 signaling, providing a novel mechanism for the increased susceptibility of infections in asthmatic patients.

Dataset Information

IL-13 desensitizes ?2-adrenergic receptors in human airway epithelial cells through a 15-lipoxygenase/G protein receptor kinase 2 mechanism.

Publications

IL-13 desensitizes β2-adrenergic receptors in human airway epithelial cells through a 15-lipoxygenase/G protein receptor kinase 2 mechanism.

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