Jing-Guo Wei

Identification of Signaling Pathways Involved in Aberrant Production of Adipokines in Adipocytes Undergoing Oxidative Stress

BACKGROUND AND AIMS In obesity, oxidative stress is responsible for the aberrant production of adipokines such as adiponectin, plasminogen activator inhibitor (PAI)-1 and interleukin-6 (IL-6), which is causally associated with obesity-related inflammation, insulin resistance and cardiovascular disease. However, the signaling transduction pathways participating in adipokine dysregulation induced by oxidative stress are largely unknown. Thus, the aim of the present study was to identify possible involved signaling pathways. METHODS 3T3-L1 cells were differentiated into adipocytes and underwent oxidative stress by exposure to extraneous H(2)O(2). Quantitative PCR and immunoassays were performed to determine mRNA and protein levels of adipokines (adiponectin, PAI-1 and IL-6), respectively. Possible signaling pathways involved were high-throughout identified by Bioplex phosphoprotein assays and subsequently confirmed by inhibition of the targeted protein kinases such as Akt, ERK1/2, JAK/STAT, JNK, and p70 S6K, respectively. RESULTS H(2)O(2) markedly suppressed adiponectin mRNA expression as well as protein secretion; however, it enhanced PAI-1 and IL-6 production in mature adipocytes. Akt,JAK/STAT and ERK1/2 participated in the H(2)O(2)-induced increase of PAI-1 and IL-6 expression, whereas adiponectin expression was reduced by H(2)O(2) via Akt and JAK/STAT. CONCLUSIONS Akt and JAK/STAT are congenerous pathways through which oxidative stress downregulates adiponectin and upregulates PAI-1 and IL-6 expression. ERK1/2 participates not in H(2)O(2)-induced decrease of adiponectin expression, but in the increase of PAI-1 and IL-6.

Alteration of tight junctions in pulmonary microvascular endothelial cells in bleomycin-treated rats.

Macrophages and eosinophils that infiltrate the lung interstitium are active promoters of bleomycin (BLM)-induced pulmonary fibrosis. Leukocyte infiltration indicates disrupted barrier function in endothelial cells. The aims of this study were to investigate tight junctions (TJs) and their regulation of zonula occludens-1 (ZO-1) proteins in pulmonary microvascular endothelial cells (PMVECs) during BLM-induced pulmonary fibrosis and to compare the BLM model with the pneumococcus-induced pneumonia model of lung injury. The results revealed that the majority of PMVEC TJs were in an open state in BLM-treated tissue, where PMVEC paracellular permeability remained consistently higher than in controls. Macrophage accumulation in the lung interstitium was also significantly higher than in controls. Alteration of ZO-1 protein expression further supported the apparent disruption in PMVEC TJs in tissues from BLM-treated rats. These changes were markedly different from the concurrent changes in pneumococcus-infected rats. The findings suggest that changes in the ZO-1 proteins of PMVECs underlie the sustained disruption of TJs in BLM-treated animal models of pulmonary fibrosis. This dysfunction of paracellular barriers directly leads to the sustained infiltration of leukocytes and corresponding cytokine secretion, proliferation of fibroblasts, and progression of pulmonary fibrosis.

Proliferative phenotype of pulmonary microvascular endothelial cells plays a critical role in the overexpression of CTGF in the bleomycin-injured rat.

The pathogenesis of idiopathic pulmonary fibrosis (IPF) is not very clear, with evidence for the involvement of both inflammation and aberrant vascular remodeling (associated with angiogenesis). Pulmonary microvascular endothelial cells (PMVECs), which play a major role in inflammation, secrete cytokines that promote the transformation and collagen synthesis of fibroblasts. Moreover, angiogenesis is characterized by PMVEC proliferation. The main aim of this study was to confirm the role of PMVECs in pulmonary fibrosis. Accordingly, we observed the functional changes in PMVECs in bleomycin (BLM)-treated rats (pulmonary fibrosis model) in vivo, and compared them with those of rats with pneumonia. The proliferation phenotype and intracellular ionized calcium concentration ([Ca(2+)]i) of PMVECs from BLM-treated rats were also investigated. The functioning of PMVECs was abnormal in BLM-injured rats, particularly with regard to their proliferation and secretion of connective tissue growth factor (CTGF). [Ca(2+)]i was increased in the proliferated PMVECs from BLM-treated rats. The findings suggest that dysfunction of PMVECs characterized by overexpression of CTGF is critical in rat pulmonary injury induced by BLM, and is probably related with the proliferative phenotype and [Ca(2+)]i overload. It can be concluded from the results that proliferation of PMVECs plays an important role in the pathogenesis of BLM-induced PF.

Sphincter of Oddi dysfunction in hypercholesterolemic rabbits

Background and objectives The mechanisms that trigger gallbladder evacuation dysfunction, the key risk factor for gallstone formation, have not yet been fully elucidated. The sphincter of Oddi (SO) plays important roles in the regulation of gallbladder evacuation and maintenance of normal hydraulic pressure of the biliary tract. The aim of our study was to investigate the effects of hypercholesterolemia on the motility function of SO and the underlying mechanisms of SO dysfunction (SOD). Methods Forty New Zealand white rabbits were divided randomly into the control group fed with standard chow and the experimental (Ch) group fed with a high-cholesterol diet for 8 weeks. Changes in the maximal gallbladder emptying rate, gallbladder evacuation with cholecystokinin-octapeptide (CCK-8) stimulation and SO functions of both groups were measured in vivo; B ultrasound examination was used for dynamic observation of peristaltic movements in vivo; SO pressure was measured using manometry; morphological characteristics were observed by electronic microscope; laser scanning confocal fluorescence microscopy was used to identify changes in [Ca2+]i and Ca2+ oscillation in primary SO smooth muscle cells (SMCs). Results Gallbladder cholestasis was observed during early stages of gallstone formation in Ch rabbits. CCK-8 could not improve the gallbladder cholestatic state in Ch group. Passive dilation of SO significantly improved the cholestatic state in Ch rabbits (P<0.05), although the maximal gallbladder emptying rate was still lower than that of the control group. Manometry data indicted a significant increase in the base pressure of the SO low-pressure ampulla segment and high-pressure segment (P<0.05) in Ch group. laser scanning confocal fluorescence microscopy assay data indicated that [Ca2+]i in SO cells of Ch group significantly increased and were in a state of overload (P<0.05); Ca2+ oscillation signals in SO cells of Ch group were also abnormal. Conclusion Hypercholesterolemia initially induced SOD, leading to increased gallbladder evacuation resistance and cholestasis. We suggested that [Ca2+]i overload and/or Ca2+ oscillation abnormality potentially play important roles in the pathogenesis of SOD.

Effective inhibition of irradiation on human gliomas growth in vitro and in vivo after epidermal growth factor receptor silencing with RNA interference.

In this study, we found that irradiation in the presence of small interfering RNA–epidermal growth factor receptor (EGFR) arrested U373 glioma cells in G0 and G1 phases, delayed cell cycle progression, and effectively inhibited cell proliferation compared with cells that received only radiotherapy. In addition, combined therapy enhanced the percent of apoptotic U373 cells in vitro and also reduced the tumor size and increased the survival rate in tumor xenograft studies. This study demonstrates the antitumor activity of ionizing radiation therapy in combination with small interfering RNA–EGFR in gliomas both in vitro and in vivo and provides a scientific rationale for targeting EGFR to enhance the sensitivity to radiotherapy in patients with glioblastoma multiforme.