isoforms Archives - World Asthma Foundation

Cigarette Smoke Induces uPAR in Vivo and Isoforms Selectively Contribute to Bronchial Epithelial Phenotype.

Am J Respir Cell Mol Biol. 2014 Dec 9;

Authors: Portelli MA, Stewart CE, Hall IP, Brightling CE, Sayers I

Abstract
The urokinase plasminogen activator receptor (uPAR) gene (PLAUR) has been identified as an asthma susceptibility gene, with polymorphisms within that gene being associated with baseline lung function, lung function decline and lung function in a smoking population. Soluble cleaved uPAR (scuPAR), a molecule identified as a marker of increased morbidity and mortality in a number of diseases, has itself been shown to be elevated in the airways of asthma and COPD patients. However, the functionality of soluble receptor isoforms and their relationship with an important initiator for obstructive lung disease, cigarette smoke, remains undefined. In this study, we set out to determine the effect of cigarette smoke on soluble uPAR isoforms, its regulatory pathway and the resultant effect on bronchial epithelial cell function. We identified a positive association between cigarette pack/years and uPAR expression in the airway bronchial epithelium of biopsies from asthma patients (n=27, P=0.0485). In vitro, cigarette smoke promoted cleavage of uPAR from the surface of bronchial epithelial cells (1.5X induction, P<0.0001) and induced the soluble spliced isoform through changes in mRNA expression (~2X change, P<0.001), driven by loss of endogenous 3`UTR suppression. Elevated expression of the soluble isoforms resulted in a pro-remodelling cell phenotype, characterised by increased proliferation and MMP-9 expression in primary bronchial epithelial cells. This suggests that cigarette smoke elevates soluble receptor isoforms in bronchial epithelial cells through direct (cleavage), and indirect (mRNA expression) means. These findings provide further insight into how cigarette smoke may influence changes in the airways of importance to airway remodelling and obstructive lung disease progression.

PMID: 25490122 [PubMed – as supplied by publisher]

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CD44 variant isoforms are specifically expressed on peripheral blood lymphocytes from asthmatic patients.

Exp Ther Med. 2012 Jul;4(1):79-83

Authors: Yang C, Liang H, Zhao H, Jiang X

Abstract
Asthma is a disease characterized by chronic airway inflammation, and Th2 cells play a critical role in initiating and sustaining asthmatic inflammation. It has been shown that CD44 expressed on CD4(+) T cells plays a critical role in the accumulation of antigen-specific Th2 cells in the development of airway hyperresponsiveness induced by antigen challenge in the airways. The aim of this study was to determine whether there are specific CD44 variant isoforms (CD44v) expressed on lymphocytes from asthmatic patients. We collected whole blood samples from 103 normal subjects, 165 subjects with asthma and 104 with pneumonia. Peripheral blood lymphocyte isolation was performed, and total RNA was extracted from the isolated lymphocytes, using nested PCR for specific CD44v amplification on lymphocytes. Demographic variables were analyzed using linear regression in order to determine whether the expression of CD44v was correlated with these demographic features. The nested PCR results revealed that CD44v5 was expressed by 55.2% of asthma patients, which was significantly higher than levels of expression in the other groups. Lower percentages of individuals in the normal subject group exhibited expression of CD44v5 and CD44v6. The data demonstrated that the percentage of individuals in the pneumonia group expressing CD44v5 was 29.0%, but a higher percentage of these patients expressed CD44v6. CD44v5 expression was positively correlated with IgE levels (p=0.032) in the asthmatic patient group, and CD44v6 was significantly positively correlated with the neutrophil count (p<0.05). CD44v5 was expressed by a higher proportion of asthmatic patients than other subjects and thus may play an important role in the pathogenesis of asthma. These findings may offer a new target for the diagnosis and treatment of asthma and may also provide insights into the mechanisms of asthma development.

PMID: 23060926 [PubMed – as supplied by publisher]

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