Ox-LDL-induced TGF-β1 production in human alveolar epithelial cells: Involvement of the Ras/ERK/PLTP pathway

A protective role for B-1 cells and oxidation-specific epitope IgM in lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a morbid fibrotic lung disease with limited treatment options. The pathophysiology of IPF remains poorly understood, and elucidation of the cellular and molecular mechanisms of IPF pathogenesis is key to the development of new therapeutics. B-1 cells are an innate B cell population which play an important role linking innate and adaptive immunity. B-1 cells spontaneously secrete natural IgM and prevent inflammation in several disease states. One class of these IgM recognize oxidation-specific epitopes (OSE), which have been shown to be generated in lung injury and to promote fibrosis. A main B-1 cell reservoir is the pleural space, adjacent to the typical distribution of fibrosis in IPF. In this study, we demonstrate that B-1 cells are recruited to the lung during injury where they secrete IgM to OSE (IgM OSE ). We also show that the pleural B-1 cell reservoir responds to lung injury through regulation of the chemokine receptor CXCR4. Mechanistically we show that the transcription factor Id3 is a novel negative regulator of CXCR4 expression. Using mice with B-cell specific Id3 deficiency, a model of increased B-1b cells, we demonstrate decreased bleomycin-induced fibrosis compared to littermate controls. Furthermore, we show that mice deficient in secretory IgM ( sIgM -/- ) have higher mortality in response to bleomycin-induced lung injury, which is partially mitigated through airway delivery of the IgM OSE E06. Additionally, we provide insight into potential mechanisms of IgM in attenuation of fibrosis through RNA sequencing and pathway analysis, highlighting complement activation and extracellular matrix deposition as key differentially regulated pathways.

Obesity and the Development of Lung Fibrosis

Obesity is an epidemic worldwide and the obese people suffer from a range of respiratory complications including fibrotic changes in the lung. The influence of obesity on the lung is multi-factorial, which is related to both mechanical injury and various inflammatory mediators produced by excessive adipose tissues, and infiltrated immune cells. Adiposity causes increased production of inflammatory mediators, for example, cytokines, chemokines, and adipokines, both locally and in the systemic circulation, thereby rendering susceptibility to respiratory diseases, and altered responses. Lung fibrosis is closely related to chronic inflammation in the lung. Current data suggest a link between lung fibrosis and diet-induced obesity, although the mechanism remains incomplete understood. This review summarizes findings on the association of lung fibrosis with obesity, highlights the role of several critical inflammatory mediators (e.g., TNF-α, TGF-β, and MCP-1) in obesity related lung fibrosis and the implication of obesity in the outcomes of idiopathic pulmonary fibrosis patients.

Untargeted metabolomics of human plasma reveal lipid markers unique to chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis

Chronic obstructive pulmonary disease (COPD) is characterised by airway inflammation and progressive airflow limitation, whereas idiopathic pulmonary fibrosis (IPF) is characterised by a restrictive pattern due to fibrosis and impaired gas exchange. We undertook metabolomic analysis of blood samples in IPF, COPD and healthy controls (HC) to determine differences in circulating molecules and identify novel pathogenic pathways. An untargeted metabolomics using an ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometer (UHPLC-QTOF-MS) was performed to profile plasma of patients with COPD (n = 21), and IPF (n = 24) in comparison to plasma from healthy controls (HC; n = 20). The most significant features were identified using multiple database matching. One-way ANOVA and variable importance in projection (VIP) scores were also used to highlight metabolites that influence the specific disease groups. Non-polar metabolites such as fatty acids (FA) and membrane lipids were well resolved and a total of 4805 features were identified. The most prominent metabolite composition differences in lipid mediators identified at ∼2-3 fold higher in both diseases compared to HC were palmitoleic acid, oleic acid and linoleic acid; and dihydrotestosterone was lower in both diseases. We demonstrated that COPD and IPF were characterised by systemic changes in lipid constituents such as essential FA sampled from circulating plasma.

The role of oxidised self-lipids and alveolar macrophage CD1b expression in COPD

In chronic obstructive pulmonary disease (COPD) apoptotic bronchial epithelial cells are increased, and their phagocytosis by alveolar macrophages (AM) is decreased alongside bacterial phagocytosis. Epithelial cellular lipids, including those exposed on uncleared apoptotic bodies, can become oxidized, and may be recognized and presented as non-self by antigen presenting cells. CD1b is a lipid-presenting protein, previously only described in dendritic cells. We investigated whether CD1b is upregulated in COPD AM, and whether lipid oxidation products are found in the airways of cigarette smoke (CS) exposed mice. We also characterise CD1b for the first time in a range of macrophages and assess CD1b expression and phagocytic function in response to oxidised lipid. Bronchoalveolar lavage and exhaled breath condensate were collected from never-smoker, current-smoker, and COPD patients and AM CD1b expression and airway 8-isoprostane levels assessed. Malondialdehyde was measured in CS-exposed mouse airways by confocal/immunofluorescence. Oxidation of lipids produced from CS-exposed 16HBE14o- (HBE) bronchial epithelial cells was assessed by spectrophotometry and changes in lipid classes assessed by mass spectrometry. 16HBE cell toxicity was measured by flow cytometry as was phagocytosis, CD1b expression, HLA class I/II, and mannose receptor (MR) in monocyte derived macrophages (MDM). AM CD1b was significantly increased in COPD smokers (4.5 fold), COPD ex-smokers (4.3 fold), and smokers (3.9 fold), and AM CD1b significantly correlated with disease severity (FEV₁) and smoking pack years. Airway 8-isoprostane also increased in smokers and COPD smokers and ex-smokers. Malondialdehyde was significantly increased in the bronchial epithelium of CS-exposed mice (MFI of 18.18 vs 23.50 for control). Oxidised lipid was produced from CS-exposed bronchial epithelial cells (9.8-fold of control) and showed a different overall lipid makeup to that of control total cellular lipid. This oxidised epithelial lipid significantly upregulated MDM CD1b, caused bronchial epithelial cell toxicity, and reduced MDM phagocytic capacity and MR in a dose dependent manner. Increased levels of oxidised lipids in the airways of COPD patients may be responsible for reduced phagocytosis and may become a self-antigen to be presented by CD1b on macrophages to perpetuate disease progression despite smoking cessation.

The Role of Phospholipid Transfer Protein in the Development of Atherosclerosis

PURPOSE OF REVIEW

Phospholipid transfer protein (PLTP), a member of lipid transfer protein family, is an important protein involved in lipid metabolism in the circulation. This article reviews recent PLTP research progresses, involving lipoprotein metabolism and atherogenesis.

RECENT FINDINGS

PLTP activity influences atherogenic and anti-atherogenic lipoprotein levels. Human serum PLTP activity is a risk factor for human cardiovascular disease and is an independent predictor of all-cause mortality. PLTP deficiency reduces VLDL and LDL levels and attenuates atherosclerosis in mouse models, while PLTP overexpression exerts an opposite effect. Both PLTP deficiency and overexpression result in reduction of HDL which has different size, inflammatory index, and lipid composition. Moreover, although both PLTP deficiency and overexpression reduce cholesterol efflux capacity, but this effect has no impact in macrophage reverse cholesterol transport in mice. Furthermore, PLTP activity is related with metabolic syndrome, thrombosis, and inflammation. PLTP could be target for the treatment of dyslipidemia and atherosclerosis, although some potential off-target effects should be noted.

Puerarin protects vascular smooth muscle cells from oxidized low-density lipoprotein-induced reductions in viability via inhibition of the p38 MAPK and JNK signaling pathways

Puerarin belongs to the family of flavonoids extracted from Pueraria lobata (Wild.) Ohwi, which exhibits antioxidative, anti-inflammatory, anti-hyperglycemic, antitumor, anti-hypertensive and anti-atherosclerotic activities. In the present study, the effects of puerarin on oxidized low-density lipoprotein (ox-LDL)-stimulated vascular smooth muscle cells (VSMCs) were explored to understand the mechanisms underlying the anti-atherosclerotic effects of puerarin. VSMCs were treated with various concentrations of puerarin (0, 20, 40 and 80 µM) prior to stimulation with ox-LDL (50 µg/ml). VSMC viability was evaluated by performing MTT and Cell Counting Kit-8 assays. Moreover, superoxide dismutase (SOD) and malondialdehyde (MDA) levels were measured by performing ELISAs. The mRNA expression levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were determined via reverse transcription-quantitative PCR. Western blotting was conducted to assess the levels of p38-MAPK and JNK phosphorylation. The results indicated that puerarin inhibited ox-LDL-induced VSMC viability. Moreover, puerarin significantly decreased the mRNA expression levels of IL-6 and TNF-α, significantly reduced the production of MDA and significantly increased SOD activity in ox-LDL-stimulated VSMCs. Puerarin also inhibited ox-LDL-induced phosphorylation of p38 and JNK in VSMCs. The results suggested that puerarin reduced ox-LDL-induced VSMC viability via inhibition of the p38 MAPK and JNK signaling pathways. The present study provided theoretical evidence that puerarin may serve as a therapeutic agent to reduce the development of atherosclerosis.

Bax-inhibiting peptide attenuates bleomycin-induced lung injury in mice

Bax is a pro-apoptotic member of the Bcl-2 family of proteins, and plays a central role in mitochondria-dependent apoptosis. Several lines of evidence have implied that Bax is involved in both epithelial apoptosis and fibroblast proliferation in idiopathic pulmonary fibrosis; however, the mechanisms remain unknown. Bax-inhibiting peptide V5 (BIP-V5) exhibits membrane permeability and inhibits the activation of Bax.

The purpose of this study was to investigate whether the control of Bax activity by BIP-V5 reduces the degree of bleomycin-induced lung injury. C57BL/6J mice were administered bleomycin and BIP-V5 intratracheally on day 0. Bronchoalveolar lavage fluid and lung tissue were obtained on day 7. Human pulmonary alveolar epithelial cells (A549 cells) and mouse pulmonary alveolar epithelial cells (LA-4 cells) were stimulated with bleomycin to induce apoptosis.

Administration of BIP-V5 improved the survival rate and degree of bleomycin-induced lung injury by suppressing Bax activation in mice. BIP-V5 treatment decreased bleomycin-induced apoptosis of alveolar epithelial cell lines (A549 cells and LA-4 cells) by suppressing Bax activation. These results indicate that administration of BIP-V5 may constitute a novel therapeutic strategy against lung injury.

Summary: The inhibiting peptide for Bax, a pro-apoptotic member of the Bcl-2 family of proteins, ameliorates bleomycin-induced lung injury in mice via apoptosis suppression in epithelial cells.

Selenium modulates MMP2 expression through the TGFβ1/Smad signalling pathway in human umbilical vein endothelial cells and rabbits following lipid disturbance

BACKGROUND

A high-fat diet is a major risk factor for coronary heart diseases. Matrix metalloprotease (MMP) expression is changed in many cardiovascular diseases. Selenium, which is an important trace element in animals, has a close relationship with cardiovascular diseases. The TGFβ1/Smad signalling pathway is ubiquitous in diverse tissues and cells, and it is also associated with the occurrence and development of cardiovascular diseases. Therefore, in this study, we aimed to determine selenium's effect on lipid metabolism, atherosclerotic plaque formation, and MMP2 expression, as well as the underlying functional mechanism.

METHODS AND RESULTS

In vivo tests: 24 male New Zealand white rabbits were randomly divided into 4 groups: regular diet, high-fat diet, high-fat diet+selenium and regular diet+selenium groups. The high-fat diet induced the lipid disturbances of rabbits at week 12. Selenium supplementation lowered total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) levels (p<0.01). Selenium supplementation also suppressed MMP2 over-expression in thoracic aortas. In vitro tests: Human umbilical vein endothelial cells (HUVECs) were treated with different concentrations of selenium or ox-LDL. Ox-LDL promoted MMP2 expression by increasing TGFβ1, pSmad2, pSmad3 and Smad3 expression (p<0.01). Selenium attenuated MMP2 over-expression by regulating the TGFβ1/Smad signalling pathway.

CONCLUSIONS

Selenium suppressed high-fat diet-induced MMP2 over-expression in vivo by improving lipid metabolism. In vitro, selenium attenuated MMP2 over-expression through the TGFβ1/Smad signalling pathway.

Cigarette smoke extract induces the epithelial-to-mesenchymal transition via the PLTP/TGF-β1/Smad2 pathway in RLE-6TN cells

Aim: The role of phospholipid transfer protein (PLTP) in the pathogenesis of the cigarette smoke extract (CSE)-induced epithelial-to-mesenchymal transition (EMT) has not been well described. In this study we investigated the effect of PLTP on the CSE-induced EMT of rat alveolar epithelial cells (RLE-6TN). Methods: The rats were exposed to air and cigarette smoke (CS) for 3 d and then the lungs were sectioned and examined using immunohistochemistry techniques. RLE-6TN cells were treated with different concentrations of CSE. PLTP siRNA was transfected into cells or SB431542 - an inhibitor of the transforming growth factor-β1 (TGF-β1) type I receptor - was administered prior to CSE exposure. The expression of EMT markers and PLTP was detected by qRT-PCR. The levels of PLTP, TGF-β1, p-Smad2, Smad2, and EMT proteins were analyzed by western blotting. Results: Lung injury and EMT were accompanied by up-regulation of PLTP and TGF-β1 in the CS-exposed rat model. EMT was induced by CSE in vitro, and the expression of PLTP, TGF-β1, and p-Smad2 was significantly increased after exposure to CSE (P < 0.05). Moreover, knockdown of PLTP and blocking of the TGF-β1/Smad2 pathway restrained the CSE-induced activation of the TGF-β1/Smad2 pathway and partly inhibited EMT by reversing E-cadherin expression and retarding the induction of N-cadherin and vimentin. In contrast, SB431542 had no effect on the expression of PLTP, while it ameliorated CSE-induced EMT. Conclusion: PLTP promotes the CSE-induced EMT process, in which the TGF-β1/Smad2 pathway is activated.

Cigarette smoke extract alters the cell cycle via the phospholipid transfer protein/transforming growth factor-β1/CyclinD1/CDK4 pathway

This study was aimed to investigate the effect of phospholipid transfer protein (PLTP) on cigarette smoke extract (CSE)-induced alteration of the cell cycle and the possible mechanism. Male Wistar rats and the rat alveolar epithelial cell line (RLE-6TN) were exposed to normal air or different concentrations of CSE. Then PLTP siRNA was transfected into cells and an inhibitor of transforming growth factor-β1 (TGF-β1) was administered prior to CSE exposure. Histological changes and cell cycle stage were recorded, as were the expression levels of PLTP, TGF-β1, CyclinD1 and CDK4. Resulting morphological changes included diffuse interstitial substance incrassation and elevated alveolar rupturing. Flow cytometry analysis revealed an increase in the number of cells in the G1 phase in a time- and dose-related manner. Both PLTP and TGF-β1 were up-regulated at protein and mRNA levels, whereas CyclinD1 and CDK4 expression was down-regulated after CSE exposure. Furthermore, PLTP siRNA significantly suppressed CSE-induced TGF-β1 expression, resulting in up-regulation of CyclinD1 and CDK4, but the TGF-β1 inhibitor was not able to abrogate CSE-induced PLTP over-expression. In conclusion, PLTP may operate upstream of the TGF-β1/CyclinD1/CDK4 pathway and may mediate the CSE-induced G1 arrest in RLE-6TN cells. Our work provides some new insight into the relation between PLTP and cell cycle progression.

WNT/β-catenin signaling regulates cigarette smoke-induced airway inflammation via the PPARδ/p38 pathway

The mechanisms of WNT/β-catenin signaling involved in airway inflammation of chronic obstructive pulmonary disease (COPD) remain unknown, although recent observations have suggested an important contribution of the pathway in pulmonary parenchymal tissue repair and airway epithelium differentiation. We investigated the role of WNT/β-catenin signaling in cigarette smoke (CS)-related airway inflammation using patient lung tissues, human bronchial epithelial cells (16HBECs), and mouse models. Reduced activity of WNT/β-catenin signaling was observed in the airway epithelium of smokers with or without COPD. The mRNA expression of WNT transcription factor TCF4 negatively correlated with the pack year. The mRNA levels of WNT receptor FZD4 negatively correlated with the mRNA levels of IL-1β. CS exposure decreased the activity of WNT/β-catenin signaling in both 16HBECs and mice. In vitro studies demonstrated the upregulation of inflammatory cytokines TNF-α and IL-1β secretion induced by CS extract (CSE) could be attenuated by β-catenin activator SB216763 and be exacerbated by β-catenin small-interfering RNA (siRNA), respectively. Furthermore, the decrease in the expression of peroxisome proliferator-activated receptor (PPARδ) induced by CSE stimulation could be rescued by SB216763. SB216763 also attenuated the upregulation of phosphorylated p38 mitogen-activated protein kinase (MAPK) stimulated by CSE. Both PPARδ agonist and p38 MAPK inhibitor could suppress the TNF-α and IL-1β release induced by CSE treatment. In addition, PPARδ activation could abolish β-catenin siRNA-mediated aggravation of phosphorylated p38 MAPK in response to CSE. Finally, SB216763 treatment significantly ameliorated peribronchial inflammatory cell infiltration, leukocyte influx, and the release of TNF-α and IL-1β in the bronchoalveolar lavage fluid of CS-exposed mice. Taken together, our findings indicate that the reduced activity of WNT/β-catenin signaling induced by CS may promote inflammatory cytokine production in airway epithelium and have an essential role in airway inflammation in COPD by PPARδ/p38 MAPK pathway.

Cigarette smoke extract induces apoptosis of rat alveolar Type II cells via the PLTP/TGF-β1/Smad2 pathway

Apoptosis of alveolar epithelial cells has been implicated in the pathogenesis of acute lung injury. Phospholipid transfer protein (PLTP) may play a role in apoptosis. In the present study, the effect of the novel function of PLTP in cigarette smoke extract (CSE)-induced apoptosis of alveolar epithelial cells and the possible mechanism were examined. Male Wistar rats were exposed to air and cigarette smoke (n=10/exposure) for 6h/day on 3 consecutive days, then the lungs were sectioned and examined. To investigate effects on alveolar epithelial cells, rat alveolar epithelial cells (RLE-6TN) were treated with different concentrations of CSE for various times. siRNA for PLTP was transfected into cells and an inhibitor of the transforming growth factor-β1 (TGF-β1) type I receptor was administered prior to CSE exposure. Apoptosis was measured, and mRNA expression of PLTP and TGF-β1 and protein levels of PLTP, TGF-β1, p-Smad2 and cleaved caspase-3 were analyzed. The results showed that apoptosis, as well as expression of PLTP, TGF-β1, p-Smad2 and cleaved caspase-3 were all significantly increased after CSE stimulation (P<0.05). Furthermore, the expression of TGF-β1, p-Smad2 and cleaved caspase-3 induced by CSE could be partly abrogated by knockdown of PLTP. The expression of PLTP showed no significant change as a result of TGF-β1 receptor inhibition, while cleaved caspase-3 showed a remarkable reduction. PLTP may act as an upstream signal molecule of the TGF-β1/Smad2 pathway and is likely to be involved in CSE-induced apoptosis of alveolar epithelial cells.

RIP140 contributes to foam cell formation and atherosclerosis by regulating cholesterol homeostasis in macrophages

Atherosclerosis, a syndrome with abnormal arterial walls, is one of the major causes that lead to the development of various cardiovascular diseases. The key initiator of atherosclerosis is cholesterol accumulation. The uncontrolled cholesterol deposition, mainly involving low-density lipoprotein (LDL), causes atheroma plaque formation, which initiates chronic inflammation due to the recruitment of inflammatory cells such as macrophages. Macrophages scavenge excess peripheral cholesterol and transport intracellular cholesterol to high-density lipoprotein (HDL) for excretion or storage. Cholesterol-laden macrophage-derived foam cell formation is the main cause of atherogenesis. It is critical to understand the regulatory mechanism of cholesterol homeostasis in the macrophage in order to prevent foam cells formation and further develop novel therapeutic strategies against atherosclerosis. Here we identified a protein, RIP140 (receptor interacting protein 140), which enhances macrophage-derived foam cell formation by reducing expression of reverse cholesterol transport genes, A TP-binding membrane cassette transporter A-1 (ABCA1) and ATP-binding membrane cassette transporter G-1 (ABCG1). In animal models, we found that reducing RIP140 levels by crossing macrophage-specific RIP140 knockdown (MϕRIP140KD) mice with ApoE null mice effectively ameliorates high-cholesterol diet-induced atherosclerosis. Our data suggest that reducing RIP140 levels in macrophages significantly inhibits atherosclerosis, along with markers of inflammation and the number of macrophages in a western diet fed ApoE null mouse. This study provides a proof-of-concept for RIP140 as a risk biomarker of, and a therapeutic target for, atherosclerosis.

Targeting the mevalonate cascade as a new therapeutic approach in heart disease, cancer and pulmonary disease

The cholesterol biosynthesis pathway, also known as the mevalonate (MVA) pathway, is an essential cellular pathway that is involved in diverse cell functions. The enzyme 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase (HMGCR) is the rate-limiting step in cholesterol biosynthesis and catalyzes the conversion of HMG-CoA to MVA. Given its role in cholesterol and isoprenoid biosynthesis, the regulation of HMGCR has been intensely investigated. Because all cells require a steady supply of MVA, both the sterol (i.e. cholesterol) and non-sterol (i.e. isoprenoid) products of MVA metabolism exert coordinated feedback regulation on HMGCR through different mechanisms. The proper functioning of HMGCR as the proximal enzyme in the MVA pathway is essential under both normal physiologic conditions and in many diseases given its role in cell cycle pathways and cell proliferation, cholesterol biosynthesis and metabolism, cell cytoskeletal dynamics and stability, cell membrane structure and fluidity, mitochondrial function, proliferation, and cell fate. The blockbuster statin drugs ('statins') directly bind to and inhibit HMGCR, and their use for the past thirty years has revolutionized the treatment of hypercholesterolemia and cardiovascular diseases, in particular coronary heart disease. Initially thought to exert their effects through cholesterol reduction, recent evidence indicates that statins also have pleiotropic immunomodulatory properties independent of cholesterol lowering. In this review we will focus on the therapeutic applications and mechanisms involved in the MVA cascade including Rho GTPase and Rho kinase (ROCK) signaling, statin inhibition of HMGCR, geranylgeranyltransferase (GGTase) inhibition, and farnesyltransferase (FTase) inhibition in cardiovascular disease, pulmonary diseases (e.g. asthma and chronic obstructive pulmonary disease (COPD)), and cancer.

Cathepsin G degradation of phospholipid transfer protein (PLTP) augments pulmonary inflammation

Phospholipid transfer protein (PLTP) regulates phospholipid transport in the circulation and is highly expressed within the lung epithelium, where it is secreted into the alveolar space. Since PLTP expression is increased in chronic obstructive pulmonary disease (COPD), this study aimed to determine how PLTP affects lung signaling and inflammation. Despite its increased expression, PLTP activity decreased by 80% in COPD bronchoalveolar lavage fluid (BALF) due to serine protease cleavage, primarily by cathepsin G. Likewise, PLTP BALF activity levels decreased by 20 and 40% in smoke-exposed mice and in the media of smoke-treated small airway epithelial (SAE) cells, respectively. To assess how PLTP affected inflammatory responses in a lung injury model, PLTP siRNA or recombinant protein was administered to the lungs of mice prior to LPS challenge. Silencing PLTP at baseline caused a 68% increase in inflammatory cell infiltration, a 120 and 340% increase in ERK and NF-κB activation, and increased MMP-9, IL1β, and IFN-γ levels after LPS treatment by 39, 140, and 190%, respectively. Conversely, PLTP protein administration countered these effects in this model. Thus, these findings establish a novel anti-inflammatory function of PLTP in the lung and suggest that proteolytic cleavage of PLTP by cathepsin G may enhance the injurious inflammatory responses that occur in COPD.

Thioredoxin1 downregulates oxidized low-density lipoprotein-induced adhesion molecule expression via Smad3 protein

Atherosclerosis is a chronic inflammation disease that is initiated by endothelial cell injury. Oxidized low-density lipoprotein (ox-LDL) is directly associated with chronic vascular inflammation. To understand whether thioredoxin1 (Trx1) participates in an antiinflammatory defense mechanism in atherosclerosis, we investigated the effect of Trx1 on the expression of two adhesion molecules, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1), in human umbilical vein endothelial cells (HUVECs). Thioredoxin1 and dominant-negative mutant thioredoxin1 (TD) were transiently overexpressed using adenovirus vector gene transfer. Our data showed that Trx1 overexpression suppressed ox-LDL-induced adhesion molecule expression in HUVECs. The overexpression of Trx1 promoted ox-LDL-induced Smad3 phosphorylation and nuclear translocation. A co-immunoprecipitation assay indicated that Smad3 continued to interact with Trx1 with or without ox-LDL stimulation. These results suggest that Trx1 inherently suppresses VCAM-1 and ICAM-1 expression in vascular endothelia and may prevent the initiation of atherosclerosis by attenuating adhesion molecule expression. The enhancement of Smad3 phosphorylation and nuclear expression appears to be primarily responsible for the Trx1-induced downregulation of adhesion molecules.

Increased serum ox-LDL levels correlated with lung function, inflammation, and oxidative stress in COPD

Chronic obstructive pulmonary disease (COPD) is associated with abnormal inflammation and high oxidative stress. Studies suggest that oxidized low density lipoprotein (ox-LDL) is involved in diseases associated with oxidative stress and inflammation. However, no data on the possible relationship between COPD and ox-LDL are available. This study compared serum levels of ox-LDL in 48 COPD patients and 32 health controls and correlated them with lung function, systematic inflammation, and oxidative stress. Serum levels of ox-LDL, C-reactive protein (CRP), and oxidative stress (measured by reactive oxygen species, ROS) were analyzed using commercial kits. Mean levels of serum ox-LDL were significantly higher in COPD patients than in controls (18.62 ± 7.56 versus 12.57 ± 5.90 mU/L, P < 0.05). Serum levels of CRP and ROS were also significantly higher in COPD patients. Serum levels of ox-LDL in COPD patients correlated inversely with FEV₁% predicted, an index of lung function (r = −0.347, P = 0.016), while they correlated positively with CRP and ROS levels. These results suggest that serum levels of ox-LDL are increased in COPD patients and that these levels are associated with lung function, inflammation, and oxidative stress in COPD. Future studies are needed to determine whether and how ox-LDL plays a role in COPD.

The effect of curcumin on sepsis-induced acute lung injury in a rat model through the inhibition of the TGF-β1/SMAD3 pathway

Curcumin has the potential to treat inflammatory diseases. This study investigated its effect on sepsis-induced acute lung injury (ALI) in a rat model. 125 healthy rats were randomly divided into five groups, including normal group, sham-operated group, sepsis group, dimethyl sulfoxide group, and curcumin-treated group (25 rats in each subgroup). Sepsis-induced acute lung injury was affected by cecal ligation and puncture surgery. At 0, 6, 12, 24, and 48 h after treatment, the lungs were harvested for histological and protein expression examinations. 24h after the initial treatment, real-time PCR and Western blot analysis showed that the expression of TGF-β1 and SMAD3-dependent signaling pathway was significantly decreased in the curcumin-treated group than other control groups (P<0.05). Therefore, curcumin played a protective role in sepsis-induced ALI, possibly through the inhibition of the expression of TGF-β1/SMAD3 pathway which may provide a new strategy for the treatment of sepsis-induced ALI.

Oleic acid induces lung injury in mice through activation of the ERK pathway

Oleic acid (OA) can induce acute lung injury in experimental models. In the present work, we used intratracheal OA injection to show augmented oedema formation, cell migration and activation, lipid mediator, and cytokine productions in the bronchoalveolar fluids of Swiss Webster mice. We also demonstrated that OA-induced pulmonary injury is dependent on ERK1/2 activation, since U0126, an inhibitor of ERK1/2 phosphorylation, blocked neutrophil migration, oedema, and lipid body formation as well as IL-6, but not IL-1β production. Using a mice strain carrying a null mutation for the TLR4 receptor, we proved that increased inflammatory parameters after OA challenges were not due to the activation of the TLR4 receptor. With OA being a Na/K-ATPase inhibitor, we suggest the possible involvement of this enzyme as an OA target triggering lung inflammation.