Signal transducer and activator of transcription 6 (STAT-6) expression and function in asthmatic bronchial epithelium

doi:10.1067/mai.2001.119554

Journal of Allergy and Clinical Immunology

Volume 108, Issue 5, November 2001, Pages 832-838

https://doi.org/10.1067/mai.2001.119554 Get rights and content

Abstract

Background: Asthma is associated with increased production of IL-4 and IL-13. Objective: Because many of the effects of these cytokines are mediated by activation of signal transducer and activator of transcription 6 (STAT-6), we investigated expression and function of this transcription factor in the airways. Methods: STAT-6 expression was investigated through use of immunohistochemistry or RT-PCR applied to bronchial biopsy specimens or brushings from normal control or asthmatic subjects. STAT-6 function was investigated by means of Western blotting and ELISA applied to primary epithelial cell cultures. Results: Immunohistochemistry revealed that the bronchial epithelium was the major site of STAT-6 expression, both cytoplasmic and nuclear staining being observed. The level of STAT-6 expression in subjects with mild asthma (median [range] percent epithelial staining, 3.4% [0% to 16.0%]; n = 14) did not differ significantly from that in normal controls (4.7% [0.0% to 20.0%]; n = 11); however, in subjects with severe asthma, epithelial STAT-6 expression (13.7% [4.8% to 25.7%]; n = 9) was increased in comparison with subjects with mild asthma and normal controls (P < .05). RT-PCR analysis showed that epithelial STAT-6 expression was heterogeneous and comprised both full-length STAT-6 and the dominant-negative variant that lacks the SH2 domain. Treatment of primary cultures of bronchial epithelial cells with IL-4 resulted in STAT-6 phosphorylation and stimulation of IL-8 secretion; however, no difference in the responses of epithelial cells was observed between normal (n = 12) and asthmatic (n = 14) donors. Conclusion: These data demonstrate expression and activation of STAT-6 in normal and asthmatic bronchial epithelium. The activity of this transcription factor is likely to play a key role in mediating the responses of the bronchial epithelium to T_H2 cytokines that are characteristic of the asthmatic phenotype. (J Allergy Clin Immunol 2001;108:832-8.)

Section snippets

Materials and methods

All materials were purchased from Sigma (Poole, United Kingdom), unless otherwise indicated.

STAT-6 expression in human airways

To investigate whether STAT-6 was a likely mediator of IL-4 and IL-13 responses in human airway mucosa, immunohistochemistry was used to determine the presence of STAT-6 in bronchial biopsy specimens of normal and asthmatic subjects. Immunohistochemical analysis revealed the ciliated columnar cells of the bronchial epithelium to be the major site of STAT-6 expression, mucus secreting goblet cells also showing prominent positive immunoreactivity around the nuclear region (Fig 1, A-C ).

Discussion

These studies have demonstrated for the first time that the expression of STAT-6 in the bronchial epithelium is higher in subjects with severe asthma than in subjects with mild asthma or normal controls. STAT-6 thus joins a variety of other transcription factors, including STAT-1,²² NFκB,²³ and AP-1,²⁴ whose levels and activity are upregulated in the asthmatic bronchial epithelium. The activity of each of these transcription factors is likely to make a substantial contribution to the

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^☆: Supported by an AstraZeneca studentship provided to R.E.M., by the Sir Jules Thorn Charitable Trust, and by the Medical Research Council, United Kingdom.

^☆☆: Reprint requests: Donna E. Davies, PhD, Division of Respiratory Cell and Molecular Biology, School of Medicine, Southampton General Hospital, Southampton, SO16 6YD, United Kingdom.

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Mechanisms of AllergySignal transducer and activator of transcription 6 (STAT-6) expression and function in asthmatic bronchial epithelium☆,☆☆

Abstract

Section snippets

Materials and methods

STAT-6 expression in human airways

Discussion

Immunol Today

J Allergy Clin Immunol

J Allergy Clin Immunol

J Allergy Clin Immunol

Biochem Biophys Res Commun

Genomics

The epidemic of allergy and asthma

Nature

Disruption of the murine IL-4 gene blocks Th2 cytokine responses

Nature

Interleukin-13: central mediator of allergic asthma

Science

Pulmonary expression of interleukin-13 causes inflammation, mucus hypersecretion, subepithelial fibrosis, physiologic abnormalities, and eotaxin production

J Clin Invest

IL-4 induces mucin gene expression and goblet cell metaplasia in vitro and in vivo

J Immunol

Upregulatory effects of interleukin-4 and interleukin-13 but not interleukin-10 on granulocyte/macrophage colony-stimulating factor production by human bronchial epithelial cells

Am J Respir Cell Mol Biol

Jaks and STATs: biological implications

Annu Rev Immunol

Essential role of Stat6 in IL-4 signalling

Nature

STATs and gene regulation

Science

Mechanisms of Allergy
Signal transducer and activator of transcription 6 (STAT-6) expression and function in asthmatic bronchial epithelium☆,☆☆