Chloride Channel 3 (CLC3), an Immune Antiporter in the Migration and Activation of Human Eosinophils in Allergic Asthma

Allergic asthma is a complex and heterogeneous disease of the airways. Eosinophils migrate to the airways under the influence of chemokines to start an excessive damage and repair cycle leading to airway inflammation and remodeling in allergic asthma. TGF-β has been closely related with eosinophils in airway remodeling. Eosinophils produce TGF-β; at the same time they are also affected by TGF-β, leading to their migration and activation. TGF-β has also been implicated in the modulation of chloride channels including CLC3, which is required for the respiratory burst by eosinophils and neutrophils, and altering the shape to cause migration of neutrophils. However, the underlying mechanism of eosinophil migration and activation is not clearly understood. In this study, the expression and roles of CLC3 in human eosinophils were investigated. Novel transcript variants of CLC3 in human peripheral blood eosinophils were found and compared among healthy, mild-to-moderate, and moderate-to-severe asthmatics. Higher expression of CLC3 was noted in blood eosinophils of mild-to-moderate asthmatics compared to the healthy counterparts. The expression was even higher than the moderate-to-severe asthmatic group. On the contrary, nasal lavage eosinophils showed higher CLC3 expression in moderate-to-severe asthmatics than mild-to-moderate. The CLC3 expression was noted in the membrane and organelles of eosinophils suggesting a broad role of this chloride channel in the pathophysiology of allergic asthma. Using different blockers and techniques, TGF-β and eotaxin-induced migration and activation of eosinophils were found to be dependent on CLC3. Molecular investigation revealed that TGF-β regulates CLC3 through PKC-δ and SMAD3. Gene analysis disclosed multiple AP-1 binding sites on CLC3 gene, suggesting an important role of AP-1 in the regulation of CLC3. Using different bioinformatics tools, an uncharacterized CLC3 promoter was identified and cloned. Promoter activity assay confirmed AP-1 as a major regulator CLC3. Identification of novel transcript variants of CLC3 and their role in allergic asthma in addition to the signaling events regulating CLC3 will help in understanding the underlying signaling events taking place in the activation and migration of eosinophils through CLC3. CLC3 transcript variants may serve as biomarkers for the identification of asthma phenotypes. Moreover, studying the complex interactions of these proteins in hyper-activated eosinophils may help in understanding the pathophysiology of allergic asthma and provide a potential therapeutic approach in allergic asthma

Grantor dc:publisher

Creighton University

Year dc:date.issued

2014

Author dc:creator

• Gaurav, Rohit

Advisor dc:contributor.advisor

• Agrawal, Devendra K.

Statement dc:rights

• Copyright is retained by the Author. A non-exclusive distribution right is granted to Creighton University and to ProQuest following the publishing model selected above.

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10504/62868

OAI identifier oai:identifier

oai:cdr.creighton.edu:10504/62868