Effects of ROS-relative NF-κB signaling on high glucose-induced TLR4 and MCP-1 expression in podocyte injury.

High glucose (HG) induced inflammation is central to progression in diabetic nephropathy (DN). Recent studies have suggested that nuclear factor-kappa B (NF-κB) signaling activation is associated with DN, and podocyte damage may be involved in orchestrating these effects. Therefore, the aim of this study was to investigate the effects of NF-κB signaling on podocytes under HG conditions. The effects of HG and NF-κB signaling on podocytes were assessed by CCK-8 assay, cellular NF-κB translocation assay, measurement of reactive oxygen species (ROS) and Western blot analysis. We found that HG reduced cell viability, activated NF-κB signaling and up-regulated toll-like receptor 4 (TLR4) and monocyte chemoattractant protein-1 (MCP-1). In these cells, NF-κB inhibition with ammonium pyrrolidinethiocarbamate (PDTC) resulted in effectively constraining TLR4 and MCP-1 up-regulation, indicating that protective effects associated with the inhibition of NF-κB were linked to TLR4 and MCP-1 down-regulation in podocytes. Furthermore, HG significantly increased the production of intracellular ROS. Pretreatment with N-acetyl-l-cysteine (NAC) significantly inhibited intracellular ROS generation and increased cell viability, accompanied by a significant NF-κB inhibition and suppression of TLR4 and inflammatory cytokine MCP-1 expression. Collectively, our novel data suggest that HG induces the over-experssion of TLR-4 and MCP-1 through a NF-κB-dependent signaling. NF-κB-mediated increased inflammation is possibly via ROS and contributes to the cell injury. These results may provide potential therapeutic target for diabetic nephropathy in the future.

Wei M ，Li Z ，Xiao L ，Yang Z ... -  《-》

Crocin Protects Podocytes Against Oxidative Stress and Inflammation Induced by High Glucose Through Inhibition of NF-κB.

Diabetic nephropathy (DN) is a microangiopathic disease characterized by excessive urinary albumin excretion, which occurs in 30% of patients with diabetes mellitus. It is the second leading cause of end-stage renal diseases in China. Nuclear factor-kappa B (NF-κB) is reported to be closely correlated with the inflammation underlying diabetes-associated renal damage. Crocin, a plant-derived compound, has antioxidant properties that may inhibit NF-κB. In the present study, we used a conditionally immortalized mouse podocyte cell line to explore whether crocin could effectively block albuminuria. Cells were incubated with 15 or 25 mM D-glucose to mimic diabetic conditions. The expression of Wilms tumor 1 (WT-1) and synaptopodin was evaluated to identify differentiated podocytes, and the expression of nephrin, podocin, and CD2ap was measured as markers of slit diaphragms, the main structures within the glomerular filtration barrier. The high-glucose conditions led to reduced nephrin, podocin, and CD2ap expression, which was prevented by pretreatment with crocin. The oxidative stress and pro-inflammatory response of podocytes associated with DN induced by high glucose were also reduced by crocin pretreatment. Phosphorylated IκBα (p-IκBα) expression induced by high glucose was also significantly decreased by crocin pretreatment. Moreover, pyrrolidine dithiocarbamate, a NF-κB inhibitor, pyrrolidine dithio carbamate, augmented the protective effects of crocin. Our results demonstrate a protective role of crocin against damage to podocytes and slit diaphragms under high-glucose conditions via inhibition of NF-κB. This study presents a potential therapy for DN and contributes to the understanding of the mechanism underlying DN.

Li S ，Liu X ，Lei J ，Yang J ，Tian P ，Gao Y ... -  《-》

Protective effects of the suppressed NF-κB/TLR4 signaling pathway on oxidative stress of lung tissue in rat with acute lung injury.

The pathogenesis of acute lung injury (ALI) is characterized by lung inflammation and lung oxidative stress. The study was conducted in order to investigate the effect toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NF-κB) exhibited on oxidative stress in ALI. After the rats had been assigned into different groups, arterial blood, white blood cell (WBC), lung permeability index (LPI), wet/dry (W/D) ratio, TLR4 and NF-κB expression and superoxide dismutase (SOD), myeloperoxidase (MPO), malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species (ROS) were examined. Afterward, the correlation between the levels of TLR4 and NF-κB was determined. Decreased levels of PaO2 , SOD, MPO, and GSH accompanied by increased levels of PaCO2 , WBC number, LPI and W/D ratio, MDA and ROS, as well as TLR4 and NF-κB expressions in the ALI, ALI + NF-κB inhibitor, and ALI + phosphate buffer saline groups were found. Inhibition of NF-κB resulted in increased PaO2 and decreased PaCO2 levels, WBC number, and LPI and W/D ratio. Decreased expression of NF-κB increased SOD, GSH, and MPO, but decreased MDA and ROS. We also found that NF-κB inhibition resulted in the improvement of ALI in rats. TLR4 and NF-κB expressions were negatively correlated with levels of SOD, MPO, and GSH, and positively correlated with MDA and ROS levels. In summary, our findings provided evidence that inhibition of the TLR4/NF-κB signaling pathway decreases oxidative stress, thereby improving ALI. As a result, NF-κB signaling pathway has shown potential as a therapeutic target in ALI therapy.

Zhang ZM ，Wang YC ，Chen L ，Li Z ... -  《-》

Cyclopropanyldehydrocostunolide LJ attenuates high glucose-induced podocyte injury by suppressing RANKL/RANK-mediated NF-κB and MAPK signaling pathways.

The aim of this research was to investigate the effects of cyclopropanyldehydrocostunolide (also named LJ), a derivative of sesquiterpene lactones (SLs), on high glucose (HG)-induced podocyte injury and the associated molecular mechanisms. Differentiated mouse podocytes were incubated in different treatments. The migration and albumin filtration of podocytes were examined by Transwell filters. The protein and mRNA levels of MCP-1 were measured using enzyme-linked immunosorbent assay (ELISA) and quantitative real-time PCR (q-PCR). Protein expression and phosphorylation were detected by western blot, and the nuclear translocation of NF-κB was performed with a confocal microscope. The gene expression of the receptor activator for NF-κB (RANK) was silenced by small interfering RNA (siRNA). Our results showed that HG enhanced migration, albumin filtration and MCP-1 expression in podocytes. At the molecular level, HG promoted the phosphorylation of NF-κB/p65, IKKβ, IκBα, mitogen-activated protein kinase (MAPK) and the nuclear translocation of p65. LJ reversed the effects of HG in a dose-dependent manner. Furthermore, our data provided the first demonstration that the receptor activator for NF-κB ligand (RANKL) and its cognate receptor RANK were overexpressed in HG-induced podocytes and were downregulated by LJ. RANK siRNA also attenuated HG-induced podocyte injury and markedly inhibited the activation of NF-κB and MAPK signaling pathways. LJ attenuates HG-induced podocyte injury by suppressing RANKL/RANK-mediated NF-κB and MAPK signaling pathways.

Chen XW ，Liu WT ，Wang YX ，Chen WJ ，Li HY ，Chen YH ，Du XY ，Peng FF ，Zhou WD ，Xu ZZ ，Long HB ... -  《-》

High glucose induces rat mesangial cells proliferation and MCP-1 expression via ROS-mediated activation of NF-κB pathway, which is inhibited by eleutheroside E.

Yang X ，Wang Y ，Gao G 《-》