The mechanisms that orchestrate and/or perpetuate chronic airway inflammation, believed to be key factors in the progression of asthma, remain unknown. Recent evidence suggests that airway smooth muscle (ASM) synthetic function, defined as secretion of cytokines, chemokines or growth factors and expression of adhesion molecules, may play an active role in regulating airway inflammation in asthma. In the previous funding period, we identified multiple transcription factors such as NF-kappaB and NF-AT that regulate cytokine-induced inflammatory gene expression in human ASM cells. In our new preliminary studies, we found that TNFalpha activates other transcription factors IRF-1, STAT1 and STAT2, and differentially regulates the expression of CD38, IL-6, RANTES and eotaxin but not ICAM-1 via the autocrine action of secreted IFNbeta. Accordingly, the aims of this COMPETING CONTINUATION proposal seek to extend our previous findings by defining the relative contribution of each of these signaling molecules in the regulation of TNFalpha effects on synthetic functions. The central hypothesis of this proposal states that TNFalpha and autocrine IFNbeta act in synergy to differentially regulate inflammatory gene expression via the coordinated activation of STAT1/STAT2, NF-kappaB and CD38-dependent pathways.
In Aim 1, we will determine whether NF-kappaB functionally interacts with STAT1/STAT2 and IRF-1 to regulate TNFalpha-induced expression of inflammatory genes in an IFNbeta-dependent manner using cytokine promoter constructs and coimmunoprecipitation, co-localization and gel shift assays.
In Aim 2, we will identify the transcriptional mechanisms (TRAFIKK) regulating cytokine-induced IFNbeta expression in human ASM cells using dominant negative and constitutively active cDNA constructs. We will also determine the in vivo relevance of IFNbeta expression by ASM in a murine model of bronchial hyper-responsiveness by characterizing the time course of in vivo expression and/or activation of IFNbeta signaling molecules in ASM.
In Aim 3, we will characterize whether IFNbeta-dependent CD38 pathways are necessary and/or sufficient to regulate TNFalpha-induced expression of inflammatory genes in ASM cells. The role of CD38 will be investigated using CD38 -/- ASM and soluble inhibitors. The role of calcium-dependent pathways in TNFalpha-inducible genes will be assessed by examining the role of FKBP12.6 and NF-AT using gene-deficient mice, reporter constructs and soluble inhibitors. Because of the importance of inflammatory cytokines/chemokines in asthma, results from our studies will determine that ASM-derived cytokines participate in the regulation of airway inflammation not only via paracrine effects but also via the autocrine modulation of ASM synthetic function. Thus, understanding the transcriptional mechanisms regulating the expression of inflammatory genes in ASM will likely lead to new therapeutic approaches for the treatment of asthma.
|Bhandare, Reena; Damera, Gautam; Banerjee, Audreesh et al. (2010) Glucocorticoid receptor interacting protein-1 restores glucocorticoid responsiveness in steroid-resistant airway structural cells. Am J Respir Cell Mol Biol 42:9-15|
|Amrani, Yassine; Syed, Farhat; Huang, Chris et al. (2010) Expression and activation of the oxytocin receptor in airway smooth muscle cells: Regulation by TNFalpha and IL-13. Respir Res 11:104|
|Goncharova, Elena A; Goncharov, Dmitry A; Damera, Gautam et al. (2009) Signal transducer and activator of transcription 3 is required for abnormal proliferation and survival of TSC2-deficient cells: relevance to pulmonary lymphangioleiomyomatosis. Mol Pharmacol 76:766-77|
|Panettieri Jr, Reynold A (2009) Asthma persistence versus progression: does airway smooth muscle function predict irreversible airflow obstruction? Allergy Asthma Proc 30:103-8|
|Tliba, Omar; Panettieri Jr, Reynold A (2009) Noncontractile functions of airway smooth muscle cells in asthma. Annu Rev Physiol 71:509-35|
|Damera, Gautam; Tliba, Omar; Panettieri Jr, Reynold A (2009) Airway smooth muscle as an immunomodulatory cell. Pulm Pharmacol Ther 22:353-9|
|Jain, Deepika; Keslacy, Stefan; Tliba, Omar et al. (2008) Essential role of IFNbeta and CD38 in TNFalpha-induced airway smooth muscle hyper-responsiveness. Immunobiology 213:499-509|
|Tliba, Omar; Damera, Gautam; Banerjee, Audreesh et al. (2008) Cytokines induce an early steroid resistance in airway smooth muscle cells: novel role of interferon regulatory factor-1. Am J Respir Cell Mol Biol 38:463-72|
|Tliba, Omar; Amrani, Yassine (2008) Airway smooth muscle cell as an inflammatory cell: lessons learned from interferon signaling pathways. Proc Am Thorac Soc 5:106-12|
|Goncharova, Elena A; Goncharov, Dmitry A; Chisolm, Amelia et al. (2008) Interferon beta augments tuberous sclerosis complex 2 (TSC2)-dependent inhibition of TSC2-null ELT3 and human lymphangioleiomyomatosis-derived cell proliferation. Mol Pharmacol 73:778-88|
Showing the most recent 10 out of 46 publications