Chlamydophila pneumoniae enhances secretion of VEGF, TGF-beta and TIMP-1 from human bronchial epithelial cells under Th2 dominant microenvironment

PURPOSE: Chlamydophila pneumoniae infection in the airways is thought to be associated with the pathogenesis of asthma, especially in non-atopic severe asthma with irreversible airway obstruction that may be related to airway remodeling. Here, we investigated whether C. pneumoniae infection enhances the secretion of critical chemical mediators for airway remodeling, such as VEGF, TGF-beta, and TIMP-1, in human bronchial epithelial cells (BECs) in a Th2-dominant microenvironment. METHODS: Human bronchial epithelial cells (BEAS-2B cells) were infected with C. pneumoniae strain TW183 and cultured in both a Th1-dominant microenvironment with INF-gamma and a Th2-dominant microenvironment with IL-4 or IL-13 added to the culture medium. The VEGF, TGF-beta, and TIMP-1 levels in the culture supernatants were measured using enzyme-linked immunosorbent assays (ELISA). The activation of NF-kappaB in each experimental condition was determined using an electrophoretic mobility shift assay. RESULTS: Chlamydophila pneumoniae-infected BECs showed enhanced secretion of VEGF, TGF-beta, and TIMP-1 compared with non-infected BECs. The levels of cytokines secreted from BECs were increased more when IL-13 was added to the culture medium. C. pneumoniae-infected BECs also showed increased NF-kappaB activation. CONCLUSIONS: These results suggest that C. pneumoniae plays a role in the pathogenesis of airway remodeling in asthma, revealing a Th2-dominant immune response. Further studies are required to clarify the precise mechanism of C. pneumoniae infection in airway remodeling.

Minimal amount of insulin can reverse diabetic heart function: Sarcoplasmic reticulum Ca2+ transport and phospholamban protein expression

In the present study, the underlying mechanisms for diabetic functional derangement and insulin effect on diabetic cardiomyopathy were investigated with respect to sarcoplasmic reticulum (SR) Ca2+-ATPase and phospholamban at the transcriptional and translational levels. The maximal Ca2+ uptake and the affinity of Ca2+-ATPase for Ca2+ were decreased in streptozotocin-induced diabetic rat cardiac SR, however, even minimal amount of insulin could reverse both parameters. Levels of both mRNA and protein of phospholamban were significantly increased in diabetic rat hearts, whereas the mRNA and protein levels of SR Ca2+-ATPase were significantly decreased. In case of phospholamban, insulin treatment reverses these parameters to normal levels. Minimal amount of insulin could reverse the protein levels; however, it could not reverse the mRNA level of SR Ca2+-ATPase at all. Thus, the decreased SR Ca2+ uptake appear to be largely attributed to the decreased SR Ca2+-ATPase level, which is further impaired due to the inhibition by the increased level of phospholamban. These results indicate that insulin is involved in the control of intracellular Ca2+ in the cardiomyocyte through multiple target proteins via multiple mechanisms for the decrease in the mRNA for both SR Ca2+-ATPase and phospholamban which are unknown and needs further study.

Thyroid hormone-induced alterations of Ca2+-ATPase and phospholamban protein expression in cardiac sarcoplasmic reticulum

Alterations of cardiovascular function associated with various thyroid states have been studied. In hyperthyroidism left ventricular contractility and relaxation velocity were increased, whereas these parameters were decreased in hypothyroidism. The mechanisms for these changes have been suggested to include alterations in the expression and/or activity levels of various proteins; alpha-myosin heavy chain, beta-myosin heavy chain, beta-receptors, the guanine nucleotide-binding regulatory protein, and the sarcolemmal Ca2+-ATPase. All these cellular alterations may be associated with changes in the intracellular Ca2+ concentration. The most important regulator of intracellular Ca2+ concentration is the sarcoplasmic reticulum (SR), which serves as a Ca2+ sink during relaxation and as a Ca2+ source during contraction. The Ca2+-ATPase and phospholamban are the most important proteins in the SR membrane for muscle relaxation. The dephosphorylated phospholamban inhibits the SR Ca2+-ATPase through a direct interaction, and phosphorylation of phospholamban relieves the inhibition. In the present study, quantitative changes of Ca2+-ATPase and phospholamban expression and the functional consequences of these changes in various thyroid states were investigated. The effects of thyroid hormones on (1) SR Ca2+ uptake, (2) phosphorylation levels of phospholamban, (3) SR Ca2+-ATPase and phospholamban protein levels, (4) phospholamban mRNA levels were examined. Our findings indicate that hyperthyroidism is associated with increases in Ca2+-ATPase and decreases in phospholamban levels whereas opposite changes in these proteins occur in hypothyroidism.

Thyroid hormone-induced alterations of ryanodine and dihydropyridine receptor protein expression in rat hear

Thyroid hormone-induced cellular dysfunctions may be associated with changes in the intracellular Ca2+ concentration. The ryanodine receptor, a Ca2+ release channel of the SR, is responsible for the rapid release of Ca2+ that activates cardiac muscle contraction. In the excitation-contaction coupling cascade, activation of ryanodine receptors is initiated by the activity of sarcolemmal Ca2+ channels, the dihydropyridine receptors. In hyperthyroidism left ventricular contractility and relaxation velocity were increased, whereas these parameters were decreased in hypothyroidism. The mechanisms for these changes have been suggested to include alterations in the expression and/or activity levels of various proteins. In the present study, quantitative changes of ryanodine receptors and the dihydropyridine receptors, and the functional consequences of these changes in various thyroid states were investigated. In hyperthyroid hearts, (3H)ryanodine binding and ryanodine receptor mRNA levels were increased, but protein levels of ryanodine were not changed significantly. However, the above parameters were markedly decreased in hypothyroid hearts. In case of dihydropyridine receptor, there were a significant increase in the mRNA and protein levels, and (3H)nitrendipine binding, whereas no changes were observed in these parameters of hypothyroid hearts. Our findings indicate that hyperthyroidism is associated with increases in ryanodine receptor and dihydropyridine receptor expression levels, which is well correlated with the ryanodine and dihydropyridine binding. Whereas opposite changes occur in ryanodine receptor of the hypothyroid hearts.