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ABSTRACT: Glucose concentrations of normal human airway surface liquid are approximately 12.5 times lower than blood glucose concentrations indicating that glucose uptake by epithelial cells may play a role in maintaining lung glucose homeostasis. We have therefore investigated potential glucose uptake mechanisms in non-polarised and polarised H441 human airway epithelial cells and bronchial biopsies. We detected mRNA and protein for glucose transporter type 2 (GLUT2) and glucose transporter type 4 (GLUT4) in non-polarised cells but GLUT4 was not detected in the plasma membrane. In polarised cells, GLUT2 protein was detected in both apical and basolateral membranes. Furthermore, GLUT2 protein was localised to epithelial cells of human bronchial mucosa biopsies. In non-polarised H441 cells, uptake of D: -glucose and deoxyglucose was similar. Uptake of both was inhibited by phloretin indicating that glucose uptake was via GLUT-mediated transport. Phloretin-sensitive transport remained the predominant route for glucose uptake across apical and basolateral membranes of polarised cells and was maximal at 5-10 mM glucose. We could not conclusively demonstrate sodium/glucose transporter-mediated transport in non-polarised or polarised cells. Our study provides the first evidence that glucose transport in human airway epithelial cells in vitro and in vivo utilises GLUT2 transporters. We speculate that these transporters could contribute to glucose uptake/homeostasis in the human airway.
Pflügers Archiv - European Journal of Physiology 09/2008; 456(5):991-1003. · 4.46 Impact Factor
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Sun Ying,
Brian O'Connor, Jonathan Ratoff,
Qiu Meng,
Cailong Fang,
David Cousins,
Guizhen Zhang,
Shuyan Gu,
Zhongli Gao,
Betty Shamji,
Matthew J Edwards,
Tak H Lee,
Chris J Corrigan
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ABSTRACT: Asthma and chronic obstructive pulmonary disease (COPD) are associated with Th2 and Th1 differentiated T cells. The cytokine thymic stromal lymphopoietin (TSLP) promotes differentiation of Th2 T cells and secretion of chemokines which preferentially attract them. We hypothesized that there is distinct airways expression of TSLP and chemokines which preferentially attract Th1- and Th2-type T cells, and influx of T cells bearing their receptors in asthma and COPD. In situ hybridization, immunohistochemistry, and ELISA were used to examine the expression and cellular provenance of TSLP, Th2-attracting (TARC/CCL17, MDC/CCL22, I-309/CCL1), and Th1-attracting (IP-10/CXCL10, I-TAC/CXCL11) chemokines in the bronchial mucosa and bronchoalveolar lavage fluid of subjects with moderate/severe asthma, COPD, and controls. Cells expressing mRNA encoding TSLP, TARC/CCL17, MDC/CCL22, and IP-10/CXCL10, but not I-TAC/CXCL11 and I-309/CCL1, were significantly increased in severe asthma and COPD as compared with non-smoker controls (p < 0.02). This pattern was reflected in bronchoalveolar lavage fluid protein concentrations. Expression of the same chemokines was also increased in ex- and current smokers. The cellular sources of TSLP and chemokines were strikingly similar in severe asthma and COPD. The numbers of total bronchial mucosal T cells expressing the chemokine receptors CCR4, CCR8, and CXCR3 did not significantly differ in asthma, COPD, and controls. Both asthma and COPD are associated with elevated bronchial mucosal expression of TSLP and the same Th1- and Th2-attracting chemokines. Increased expression of these chemokines is not, however, associated with selective accumulation of T cells bearing their receptors.
The Journal of Immunology 08/2008; 181(4):2790-8. · 5.79 Impact Factor
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ABSTRACT: Overexpression of the transcriptional regulatory factor activator protein 1 might contribute to T-cell glucocorticoid (GC) refractoriness in GC-resistant asthma.
We sought to address the hypothesis that clinically GC-resistant asthma is accompanied by failure of systemic GCs to inhibit phosphorylation of c-jun and c-jun N-terminal kinase (JNK) in bronchial mucosal cells.
We performed enumeration of total (CD45+) leukocytes and cells expressing c-fos and total and phosphorylated c-jun and JNK in bronchial biopsy sections from 9 GC-sensitive and 17 GC-resistant asthmatic patients taken before and after oral prednisolone (40 mg/1.72 m(2) body surface area daily for 14 days) using specific antibodies, immunohistochemistry, and image analysis.
At baseline, mean total (CD45+) mucosal leukocytes, total cells expressing phosphorylated c-jun and JNK, and mean percentages of cells in which these molecules were phosphorylated were similar in both groups, whereas mean total numbers of c-fos-immunoreactive cells were increased in the GC-resistant asthmatic subjects (P = .04). After prednisolone, the mean total cells expressing phosphorylated c-jun and JNK and the mean percentages of cells in which these molecules were phosphorylated were significantly reduced in the GC-sensitive (P < or = .02) but not the GC-resistant asthmatic subjects. Mean total CD45+ leukocytes and c-fos-immunoreactive cells were not significantly altered in either group.
Clinical GC responsiveness in asthma is accompanied by reduced phosphorylation of bronchial mucosal c-jun and JNK, a phenomenon not seen in resistant patients.
Dysregulation of activator protein 1 activation leading to clinical GC resistance might reflect identifiable environmental influences and is a target for future therapy.
Journal of Allergy and Clinical Immunology 09/2006; 118(2):368-75. · 11.00 Impact Factor
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Sun Ying,
Brian O'Connor, Jonathan Ratoff,
Qiu Meng,
Kirsty Mallett,
David Cousins,
Douglas Robinson,
Guizhen Zhang,
Jisheng Zhao,
Tak H Lee,
Chris Corrigan
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ABSTRACT: Thymic stromal lymphopoietin (TSLP) is said to increase expression of chemokines attracting Th2 T cells. We hypothesized that asthma is characterized by elevated bronchial mucosal expression of TSLP and Th2-attracting, but not Th1-attracting, chemokines as compared with controls, with selective accumulation of cells bearing receptors for these chemokines. We used in situ hybridization and immunohistochemistry to examine the expression and cellular provenance of TSLP, Th2-attracting (thymus and activation-regulated chemokine (TARC)/CCL17, macrophage-derived chemokine (MDC)/CCL22, I-309/CCL1) and Th1-attracting (IFN-gamma-inducible protein 10 (IP-10)/CXCL10, IFN-inducible T cell alpha-chemoattractant (I-TAC)/CXCL11) chemokines and expression of their receptors CCR4, CCR8, and CXCR3 in bronchial biopsies from 20 asthmatics and 15 normal controls. The numbers of cells within the bronchial epithelium and submucosa expressing mRNA for TSLP, TARC/CCL17, MDC/CCL22, and IP-10/CXCL10, but not I-TAC/CXCL11 and I-309/CCL1, were significantly increased in asthmatics as compared with controls (p </= 0.018). TSLP and TARC/CCL17 expression correlated with airway obstruction. Although the total numbers of cells expressing CCR4, CCR8, and CXCR3 did not significantly differ in the asthmatics and controls, there was evidence of selective infiltration of CD4(+)/CCR4(+) T cells in the asthmatic biopsies which correlated with TARC and MDC expression and airway obstruction. Epithelial cells, endothelial cells, neutrophils, macrophages, and mast cells were significant sources of TSLP and chemokines. Our data implicate TSLP, TARC/CCL17, MDC/CCL22, and IP-10/CXCL10 in asthma pathogenesis. These may act partly through selective development and retention, or recruitment of Th2 cells bearing their receptors.
The Journal of Immunology 07/2005; 174(12):8183-90. · 5.79 Impact Factor
