Biomedical subjects

Hays W J Young

Publications and source records attributed to Hays W J Young.

8 recordsLinked to original sources

PubMed2006

A3 adenosine receptor signaling contributes to airway mucin secretion after allergen challenge.

Mucin hypersecretion is a prominent feature of obstructive airway diseases such as asthma. Clara cells conditionally produce mucin in response to inflammatory signals in a process termed mucous metaplasia. This can be followed by mucin secretion stimulated by various signaling molecules. The cellular and molecular mechanisms that regulate mucin production and secretion are not well understood. Adenosine is a signaling nucleoside that has been implicated in airway diseases in which mucus obstruction is prominent. Furthermore, the A(3) adenosine receptor (A(3)AR) is upregulated in mucin-producing goblet cells of the airway, thereby implicating it in processes involved in mucous cell biology. Here we use genetic approaches to investigate the contribution of A(3)AR signaling to mucus production and secretion in a mouse model of allergen-induced pulmonary disease. We found that the degree of mucin production in response to allergen is similar in wild-type and A(3)AR-deficient mice, and that overexpression of this receptor in Clara cells neither induces mucin production itself, nor enhances mucin production in response to allergen challenge. Collectively, these experiments demonstrate that the A(3)AR is neither necessary nor sufficient for mucous cell metaplasia. In contrast to the lack of effect on mucin production, agonist-induced mucin secretion was increased in goblet cells overexpressing the A(3)AR, and was absent in A(3)AR-deficient mice. Thus, the A(3)AR contributes to mucin secretion in allergen-induced metaplasia. Signaling through this receptor may contribute to mucus airway obstruction seen in pulmonary disorders in which adenosine levels are elevated.

Animals↗

PubMed2006

Interactions between leukotriene C4 and interleukin 13 signaling pathways in a mouse model of airway disease.

CONTEXT: During an asthmatic episode, leukotriene C4 (LTC4) and interleukin 13 (IL-13) are released into the airways and are thought to be central mediators of the asthmatic response. However, little is known about how these molecules interact or affect each other's signaling pathway. OBJECTIVE: To determine if the LTC4 and IL-13 signaling pathways interact with each other's pathways. DESIGN: We examined airway responsiveness, cysteinyl LTs (Cys-LTs), and Cys-LT and IL-13 receptor transcript levels in wild-type mice and in mice that were deficient in gamma-glutamyl leukotrienase (an enzyme that converts LTC4 to LTD4), STAT6 (signal transducer and activator of transcription 6 [a critical molecule in IL-13 signaling]), and IL-4Ralpha (a subunit of the IL-13 receptor). RESULTS: Wild-type (C57BL/129SvEv) and gamma-glutamyl leukotrienase-deficient mice showed increased airway responsiveness after intranasal instillation of IL-13; similar results were observed after intranasal instillation of IL-13 or LTC4 in a second wild-type strain (BALB/c). Interleukin 13 treatment reduced levels of Cys-LTs in bronchoalveolar lavage fluid. This change was unaccompanied by changes in other arachidonic acid metabolites or in RNA transcript levels of enzymes associated with Cys-LT synthesis. Interleukin 13 treatment also increased transcript levels of the Cys-LT 1 and Cys-LT 2 receptors, while LTC4 increased transcript levels of the alpha1 chain of the IL-13 receptor. Furthermore, IL-4Ralpha-deficient mice had increased airway responsiveness to LTC4 but not to IL-13, whereas STAT6-deficient mice failed to respond to either agonist. CONCLUSIONS: These findings indicate that LTC4 and IL-13 are dependent on or signal through STAT6 to increase airway responsiveness and that both agonists regulate expression of each other's receptors.

Airway Resistance↗

PubMed2005

Partially adenosine deaminase-deficient mice develop pulmonary fibrosis in association with adenosine elevations.

Adenosine, a signaling nucleoside, exhibits tissue-protective and tissue-destructive effects. Adenosine levels in tissues are controlled in part by the enzyme adenosine deaminase (ADA). ADA-deficient mice accumulate adenosine levels in multiple tissues, including the lung, where adenosine contributes to the development of pulmonary inflammation and chronic airway remodeling. The present study describes the development of pulmonary fibrosis in mice that have been genetically engineered to possess partial ADA enzyme activity and, thus, accumulate adenosine over a prolonged period of time. These partially ADA-deficient mice live for up to 5 mo and die from apparent respiratory distress. Detailed investigations of the lung histopathology of partially ADA-deficient mice revealed progressive pulmonary fibrosis marked by an increase in the number of pulmonary myofibroblasts and an increase in collagen deposition. In addition, in regions of the distal airways that did not exhibit fibrosis, an increase in the number of large foamy macrophages and a substantial enlargement of the alveolar air spaces suggest emphysemic changes. Furthermore, important proinflammatory and profibrotic signaling pathways, including IL-13 and transforming growth factor-beta1, were activated. Increases in tissue fibrosis were also seen in the liver and kidneys of these mice. These changes occurred in association with pronounced elevations of lung adenosine concentrations and alterations in lung adenosine receptor levels, supporting the hypothesis that elevation of endogenous adenosine is a proinflammatory and profibrotic signal in this model.

Adenosine↗

PubMed2004

A3 adenosine receptor signaling contributes to airway inflammation and mucus production in adenosine deaminase-deficient mice.

Adenosine signaling has been implicated in chronic lung diseases such as asthma and chronic obstructive pulmonary disease; however, the specific roles of the various adenosine receptors in processes central to these disorders are not well understood. In this study, we have investigated the role(s) of the A(3) adenosine receptor in adenosine-dependent pulmonary inflammation observed in adenosine deaminase (ADA)-deficient mice. The A(3) receptor (A(3)R) was found to be expressed in eosinophils and mucus-producing cells in the airways of ADA-deficient mice. Treatment of ADA-deficient mice with MRS 1523, a selective A(3)R antagonist, prevented airway eosinophilia and mucus production. Similar findings were seen in the lungs of ADA/A(3) double knockout mice. Although eosinophils were decreased in the airways of ADA-deficient mice following antagonism or removal of the A(3)R, elevations in circulating and lung interstitial eosinophils persisted, suggesting signaling through the A(3)R is needed for the migration of eosinophils into the airways. These findings identify an important role for the A(3)R in regulating lung eosinophilia and mucus production in an environment of elevated adenosine.

Adenosine Deaminase↗

PubMed2003

Expression of capacitative calcium TrpC proteins in rat myometrium during pregnancy.

External Ca2+ entry into myometrial smooth-muscle cells is important to uterine contraction and hence to labor progression and parturition. Proteins of the transient receptor potential (Trp) channel family are putative capacitative Ca2+ entry channels that respond to contractant-generated signals and intracellular Ca2+ store depletion. Quantitative reverse transcription-polymerase chain reaction was used to examine the relative expression of TrpC mRNAs in rat myometrium and determine their expression pattern during pregnancy and labor. rTrpC1, rTrpC2, rTrpC4, rTrpC5, rTrpC6, and rTrpC7 mRNAs, but not rTrpC3 mRNA, were expressed in nonpregnant rat myometrium. With the exception of rTrpC7, the resulting products were sequenced and found to be identical with published sequences; new rTrpC7 sequence exhibited >88% homology to mouse and human TrpC7 coding regions. Relative to beta-actin mRNA, rTrpC4 mRNA was expressed in the greatest abundance. rTrpC1, 5, and 6 mRNAs were expressed at lower levels, whereas rTrpC2 and 7 mRNAs were barely detectable. This relative expression pattern was also observed throughout the course of gestation. There were no major differences in expression of rTrpC1, 2, 4, or 7 mRNAs between Day 13 and Day 21 of gestation or labor. Rat TrpC5 and TrpC6 mRNA expression decreased in pregnancy but was not altered between Day 13 and Day 21 or in labor. Western blot analysis generally confirmed these observations with respect to protein expression. These data suggest that rTrpC4 may play a major role in regulated Ca2+ entry in myometrial cells and throughout pregnancy but do not rule out contributions from other Trp proteins.

Animals↗

PubMed2003

Abnormal alveolar development associated with elevated adenine nucleosides.

Adenosine signaling has been characterized in various physiologic systems, but little is known about the role of adenosine signaling in lung development. Alveogenesis and microvascular maturation are the final stages in lung development in mammals. Alveogenesis in the mouse begins on Postnatal Day 5, when the process of secondary septation plays a pivotal role in the expansion of the alveolar sacs and microvascular maturation. Adenosine deaminase null mice (ADA-/-) exhibit abnormalities in alveogenesis in association with elevated lung adenosine levels. Large-scale gene expression analysis of ADA-/- lungs using oligonucleotide-based microarrays revealed novel relationships between gene expression patterns and elevated lung adenosine during the stages of alveolar maturation. Genes regulating apoptosis, proliferation, and vascular development were shown to be altered, and decreased cell proliferation in association with increased alveolar type II cell apoptosis was shown to contribute to abnormal secondary septation in these mice. ADA enzyme therapy allowed for normal patterns of apoptosis, proliferation, and alveolar development in association with prevention of adenosine elevations. These findings were correlated with the presence of adenosine receptors in the developing lung, suggesting the involvement of receptor signaling. These studies provide evidence that elevated lung adenosine can lead to abnormal alveogenesis by disrupting patterns of cell proliferation and apoptosis.

Adenine Nucleotides↗

PubMed2003

Adenosine mediates IL-13-induced inflammation and remodeling in the lung and interacts in an IL-13-adenosine amplification pathway.

IL-13 is an important mediator of inflammation and remodeling. We hypothesized that adenosine accumulation, alterations in adenosine receptors, and adenosine-IL-13 autoinduction are critical events in IL-13-induced pathologies. To test this, we characterized the effects of IL-13 overexpression on the levels of adenosine, adenosine deaminase (ADA) activity, and adenosine receptors in the murine lung. We also determined whether adenosine induced IL-13 in lungs from ADA-null mice. IL-13 induced an inflammatory and remodeling response that caused respiratory failure and death. During this response, IL-13 caused a progressive increase in adenosine accumulation, inhibited ADA activity and mRNA accumulation, and augmented the expression of the A1, A2B, and A3 but not the A2A adenosine receptors. ADA enzyme therapy diminished the IL-13-induced increase in adenosine, inhibited IL-13-induced inflammation, chemokine elaboration, fibrosis, and alveolar destruction, and prolonged the survival of IL-13-transgenic animals. In addition, IL-13 was strongly induced by adenosine in ADA-null mice. These findings demonstrate that adenosine and adenosine signaling contribute to and influence the severity of IL-13-induced tissue responses. They also demonstrate that IL-13 and adenosine stimulate one another in an amplification pathway that may contribute to the nature, severity, progression, and/or chronicity of IL-13 and/or Th2-mediated disorders.

Adenosine↗

PubMed2002

Gene expression profiling in inflammatory airway disease associated with elevated adenosine.

Adenosine has been implicated as a modulator of inflammatory processes central to asthma. However, the molecular mechanisms involved are poorly understood. We used Atlas mouse cDNA arrays to analyze differential gene expression in association with lung inflammation resulting from elevated adenosine in adenosine deaminase (ADA)-deficient mice. We report that of the 1,176 genes on the array, the expression patterns of 280 genes were consistently altered. Of these genes, the steady-state levels of 93 genes were upregulated and 29 were downregulated. We also show that lowering adenosine levels with ADA enzyme therapy has striking effects on gene expression that may be associated with resolution of pulmonary eosinophilia. In addition, we confirmed the nucleic acid and protein expression of vascular endothelial growth factor and monocyte chemoattractant protein-3, two candidate genes that may be regulated by adenosine. In conclusion, high-throughput profiling of gene expression by cDNA array hybridization has provided an overview of critical regulatory genes involved in airway inflammation in ADA-deficient mice. These mice will serve as a useful in vivo model for characterizing molecular mechanisms of adenosine-mediated lung damage.

Adenosine↗