Jak/Stat and Casein Kinase Signaling Pathway Are Involved in Interleukin-6-Induced Ctgf Expression and Lung Fibrosis

Neutrophils are effector cells of general immunity and play important role in the body's defense against bacterial infection. Through their capacity to produce toxic reactive oxygen intermediates (superoxide anion and its metabolites) upon proper stimulation they are involved in the inflammatory response lead into the clearing of foreign particles including pathogenic microorganisms. However, the excessive release of toxic reactive oxygen intermediates can result in undesirable tissue damage. Therefore, to understand the cellular mechanism of superoxide anion generation in neutrophils and search for drugs that would regulate the generation of toxic reactive oxygen intermediates from neutrophils could enhance the defense mechanism against bacterial infection and attenuate the tissue damage occurring at sites of inflammation in these conditions. In our preliminary screening study, compound 8 (PC8) among the 24 synthetic 7-azabenzimidazole derivatives had better inhibitory effect on formyl-Met-Leu-Phe (fMLP)-induced superoxide anion generation from neutrophils. PC8 had no effect on phosphorylation and membrane recruitment of protein kinase B (Akt), phosphorylation of p44/42 mitogen-activated protein kinase (MAPK), p38 MAPK and MAPK-activated protein kinase 2 (MK2), whereas, decreased the [Ca2+]i casused by fMLP and cyclopiazonic acid (CPA). The aim of this project is to evaluate the mechanisms of inhibition by compound PC8 of superoxide anion generation. The following experiments including: 1) measurement of superoxide anion generation; 2) superoxide generation in neutrophil cell-free system; 3) phospholipase C activation; 4) protein kinase C activation; 5) p21-activated kinase activation; 6) cyclic AMP content; 7) NADPH oxidase activity. After these experiments, the modes of action of compound PC8 on the inhibition of superoxide anion generation from neutrophils will be apprehended.