In vitro effects of exogenous carbon monoxide on oxidative stress and lipid metabolism in macrophages

Carbon monoxide ameliorates lipopolysaccharide-induced acute lung injury via inhibition of alveolar macrophage pyroptosis

Carbon monoxide (CO) has been reported to exhibit a therapeutic effect in lipopolysaccharide (LPS)-induced acute lung injury (ALI). However, the precise mechanism by which CO confers protection against ALI remains unclear. Pyroptosis has been recently proposed to play an essential role in the initiation and progression of ALI. Thus, we investigated whether pyroptosis is involved in the protection of CO against ALI and its underlying mechanism. First, an LPS-induced ALI mouse model was established. To determine the role of pyroptosis, we evaluated histological changes and the expression levels of cleaved caspase-11, N-gasdermin D (GSDMD), and IL-1β in lung tissues, which are the indicators of pyroptosis. Inhalation of CO exhibited protective effects on LPS-induced ALI by decreasing TNF-α and IL-10 expression and ameliorating pathological changes in lung tissue. In vitro, CO significantly reduced the expression of cleaved caspase-11, N-GSDMD, IL-1β, and IL-18. In addition, it increased nuclear factor E2-related factor 2 (NRF-2) expression in a time-dependent manner in RAW 264.7 cells and decreased N-GSDMD expression. The expression of cleaved GSDMD and release of LDH were increased after treatment with a specific NRF-2 inhibitor, ML385, indicating that NRF-2 mediates the inhibition of pyroptosis by CO. Taken together, these results demonstrated that CO upregulated NRF-2 to inhibit pyroptosis and subsequently ameliorated LPS-induced ALI.

CORM-2 Pretreatment Attenuates Inflammation-mediated Islet Dysfunction

During the process of human islet isolation a cascade of stressful events are triggered and negatively influence islet yield, viability, and function, including the production of proinflammatory cytokines and activation of apoptosis. Carbon monoxide-releasing molecule 2 (CORM-2) is a donor of carbon monoxide (CO) and can release CO spontaneously. Accumulating studies suggest that CORM-2 exerts cytoprotective and anti-inflammatory properties. However, the effect of CORM-2 on islet isolation is still unclear. In this study, we found that CORM-2 pretreatment significantly decreased the expression of critical inflammatory genes, including tissue factor, intercellular adhesion molecule-1, chemokine (C-C motif) ligand 2, C-X-C motif chemokine 10, Toll-like receptor 4, interleukin-1β, interleukin-6, and tumor necrosis factor-α (TNF-α). The isolated islets of the CORM-2 pretreatment group showed reduced apoptotic rate, improved viability, and higher glucose-stimulated insulin secretion, and functional gene expression in comparison to control group. Importantly, CORM-2 pretreatment prevented the impairment caused by TNF-α, evidenced by the improved glucose-stimulated index and transplantation outcomes. The present study demonstrated the anti-inflammatory property of CORM-2 during human islet isolation, and we suggest that CORM-2 pretreatment is an appealing treatment to mitigate inflammation-mediated islet dysfunction during isolation and culture ex vivo and to preserve long-term islet survival and function.

Analysis of Low Molecular Weight Substances and Related Processes Influencing Cellular Cholesterol Efflux

Cholesterol efflux is the key process protecting the vascular system from the development of atherosclerotic lesions. Various extracellular and intracellular events affect the ability of the cell to efflux excess cholesterol. To explore the possible pathways and processes that promote or inhibit cholesterol efflux, we applied a combined cheminformatic and bioinformatic approach. We performed a comprehensive analysis of published data on the various substances influencing cholesterol efflux and found 153 low molecular weight substances that are included in the Chemical Entities of Biological Interest (ChEBI) database. Pathway enrichment was performed for substances identified within the Reactome database, and 45 substances were selected in 93 significant pathways. The most common pathways included the energy-dependent processes related to active cholesterol transport from the cell, lipoprotein metabolism and lipid transport, and signaling pathways. The activators and inhibitors of cholesterol efflux were non-uniformly distributed among the different pathways: the substances influencing ‘biological oxidations’ activate cholesterol efflux and the substances influencing ‘Signaling by GPCR and PTK6’ inhibit efflux. This analysis may be used in the search and design of efflux effectors for therapies targeting structural and functional high-density lipoprotein deficiency.

Heme, Heme Oxygenase, and Endoplasmic Reticulum Stress-A New Insight into the Pathophysiology of Vascular Diseases

The prevalence of vascular disorders continues to rise worldwide. Parallel with that, new pathophysiological pathways have been discovered, providing possible remedies for prevention and therapy in vascular diseases. Growing evidence suggests that endoplasmic reticulum (ER) stress is involved in a number of vasculopathies, including atherosclerosis, vascular brain events, and diabetes. Heme, which is released from hemoglobin or other heme proteins, triggers various pathophysiological consequence, including heme stress as well as ER stress. The potentially toxic free heme is converted by heme oxygenases (HOs) into carbon monoxide (CO), iron, and biliverdin (BV), the latter of which is reduced to bilirubin (BR). Redox-active iron is oxidized and stored by ferritin, an iron sequestering protein which exhibits ferroxidase activity. In recent years, CO, BV, and BR have been shown to control cellular processes such as inflammation, apoptosis, and antioxidant defense. This review covers our current knowledge about how heme induced endoplasmic reticulum stress (HIERS) participates in the pathogenesis of vascular disorders and highlights recent discoveries in the molecular mechanisms of HO-mediated cytoprotection in heme stress and ER stress, as well as crosstalk between ER stress and HO-1. Furthermore, we focus on the translational potential of HIERS and heme oxygenase-1 (HO-1) in atherosclerosis, diabetes mellitus, and brain hemorrhage.

The effects of cigarette smoking and smoking cessation on high-density lipoprotein functions: implications for coronary artery disease

BACKGROUND

Smoking cessation was associated with improved prognosis of coronary artery disease. This study was designed to investigate the effect of smoking cessation on high-density lipoprotein functionality in coronary artery disease patients.

METHODS

In this prospective, randomized and parallel controlled study, coronary artery disease smokers ( n = 28) and healthy smokers ( n = 30) were divided into smoking cessation group and continuous smoking group, respectively. Blood samples were collected before and after three-month smoking cessation. Plasma high-density lipoprotein was isolated by density gradient centrifugation. The ability of high-density lipoprotein against copper-induced oxidation of lipoprotein was determined to evaluate the antioxidative property of high-density lipoprotein, and the macrophage migration inhibited by high-density lipoprotein was tested to identify the antichemotactic property of high-density lipoprotein. High-density lipoprotein-induced macrophage cholesterol efflux was measured by fluorescence spectrometry using NBD cholesterol analogue. Healthy non-smoking volunteers were enrolled as the baseline control.

RESULTS

The baseline antioxidative, antichemotactic ability of high-density lipoprotein and high-density lipoprotein-induced cellular cholesterol efflux in coronary artery disease smokers and healthy smokers were significantly attenuated when compared with those in healthy non-smokers. After three-month smoking cessation, both the antioxidative ability and antichemotactic ability of high-density lipoprotein were improved significantly in coronary artery disease smokers. However, high-density lipoprotein-induced cellular cholesterol efflux was not increased by smoking cessation. In in vitro experiments, carbon monoxide reduced the antioxidative ability and nicotine enhanced the antichemotactic ability of high-density lipoprotein.

CONCLUSIONS

Smoking cessation is an effective measure to improve high-density lipoprotein functions in coronary artery disease smokers. Our study re-emphasizes the importance of smoking cessation in the secondary prevention of coronary artery disease.

The Lipidomic Analyses in Low and Highly Aggressive Ovarian Cancer Cell Lines

Despite huge advances in the research of epithelial ovarian cancer (EOC), it remains the most lethal gynecological malignancy. Peritoneal tumor cell dissemination with cell survival and drug-resistance to taxane and platinum-based chemotherapy are two of the major challenges of EOC treatment. We have generated highly aggressive EOC cell lines (ID8-P1 lines or P1) from ID8-P0 (without in vivo passage, or P0) through in vivo passage in mice. We conducted lipidomic analyses in cells from ID8-P0 versus three ID8-P1 cell lines using ultra-high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. A total of 16 classes of lipids (149 individual lipids) were analyzed and compared between P0 and P1 cells. In addition to overall lipid profiles in EOC cells, we had several novel observations. Several classes and species of lipids have been identified to be differentially present in P0 versus P1 cells, which are potentially involved in the acquired aggressiveness of P1 cells. Triacylglycerols (TAG) were dramatically increased under detachment stress in EOC cells. Since survival of EOC cells under detachment is one of the major obstacles for EOC treatment, further studies identifying the molecular mechanisms controlling TAG increase may lead to new treatment modalities for EOC.