Different Interaction Modes for Protein-disulfide Isomerase (PDI) as an Efficient Regulator and a Specific Substrate of Endoplasmic Reticulum Oxidoreductin-1α (Ero1α)

Protein-disulfide isomerase (PDI) and sulfhydryl oxidase endoplasmic reticulum oxidoreductin-1α (Ero1α) constitute the pivotal pathway for oxidative protein folding in the mammalian endoplasmic reticulum (ER). Ero1α oxidizes PDI to introduce disulfides into substrates, and PDI can feedback-regulate Ero1α activity. Here, we show the regulatory disulfide of Ero1α responds to the redox fluctuation in ER very sensitively, relying on the availability of redox active PDI. The regulation of Ero1α is rapidly facilitated by either a or a′ catalytic domain of PDI, independent of the substrate binding domain. On the other hand, activated Ero1α specifically binds to PDI via hydrophobic interactions and preferentially catalyzes the oxidation of domain a′. This asymmetry ensures PDI to function simultaneously as an oxidoreductase and an isomerase. In addition, several PDI family members are also characterized to be potent regulators of Ero1α. The novel modes for PDI as a competent regulator and a specific substrate of Ero1α govern efficient and faithful oxidative protein folding and maintain the ER redox homeostasis.     

Hyperactivity of the Ero1α Oxidase Elicits Endoplasmic Reticulum Stress but No Broad Antioxidant Response

Oxidizing equivalents for the process of oxidative protein folding in the endoplasmic reticulum (ER) of mammalian cells are mainly provided by the Ero1α oxidase. The molecular mechanisms that regulate Ero1α activity in order to harness its oxidative power are quite well understood. However, the overall cellular response to oxidative stress generated by Ero1α in the lumen of the mammalian ER is poorly characterized. Here we investigate the effects of overexpressing a hyperactive mutant (C104A/C131A) of Ero1α. We show that Ero1α hyperactivity leads to hyperoxidation of the ER oxidoreductase ERp57 and induces expression of two established unfolded protein response (UPR) targets, BiP (immunoglobulin-binding protein) and HERP (homocysteine-induced ER protein). These effects could be reverted or aggravated by N-acetylcysteine and buthionine sulfoximine, respectively. Because both agents manipulate the cellular glutathione redox buffer, we conclude that the observed effects of Ero1α-C104A/C131A overexpression are likely caused by an oxidative perturbation of the ER glutathione redox buffer. In accordance, we show that Ero1α hyperactivity affects cell viability when cellular glutathione levels are compromised. Using microarray analysis, we demonstrate that the cell reacts to the oxidative challenge caused by Ero1α hyperactivity by turning on the UPR. Moreover, this analysis allowed the identification of two new targets of the mammalian UPR, CRELD1 and c18orf45. Interestingly, a broad antioxidant response was not induced. Our findings suggest that the hyperoxidation generated by Ero1α-C104A/C131A is addressed in the ER lumen and is unlikely to exert oxidative injury throughout the cell.     

Choline kinase inhibition induces exacerbated endoplasmic reticulum stress and triggers apoptosis via CHOP in cancer cells

Endoplasmic reticulum (ER) is a central organelle in eukaryotic cells that regulates protein synthesis and maturation. Perturbation of ER functions leads to ER stress, which has been previously associated with a broad variety of diseases. ER stress is generally regarded as compensatory, but prolonged ER stress has been involved in apoptosis induced by several cytotoxic agents. Choline kinase α (ChoKα), the first enzyme in the Kennedy pathway, is responsible for the generation of phosphorylcholine (PCho) that ultimately renders phosphatidylcholine. ChoKα overexpression and high PCho levels have been detected in several cancer types. Inhibition of ChoKα has demonstrated antiproliferative and antitumor properties; however, the mechanisms underlying these activities remain poorly understood. Here, we demonstrate that ChoKα inhibitors (ChoKIs), MN58b and RSM932A, induce cell death in cancer cells (T47D, MCF7, MDA-MB231, SW620 and H460), through the prolonged activation of ER stress response. Evidence of ChoKIs-induced ER stress includes enhanced production of glucose-regulated protein, 78 kDa (GRP78), protein disulfide isomerase, IRE1α, CHOP, CCAAT/enhancer-binding protein beta (C/EBPβ) and TRB3. Although partial reduction of ChoKα levels by small interfering RNA was not sufficient to increase the production of ER stress proteins, silencing of ChoKα levels also show a decrease in CHOP overproduction induced by ChoKIs, which suggests that ER stress induction is due to a change in ChoKα protein folding after binding to ChoKIs. Silencing of CHOP expression leads to a reduction in C/EBPβ, ATF3 and GRP78 protein levels and abrogates apoptosis in tumor cells after treatment with ChoKIs, suggesting that CHOP maintains ER stress responses and triggers the pro-apoptotic signal. Consistent with the differential effect of ChoKIs in cancer and primary cells previously described, ChoKIs only promoted a transient and moderated ER stress response in the non-tumorogenic cells MCF10A. In conclusion, pharmacological inhibition of ChoKα induces cancer cell death through a mechanism that involves the activation of exaggerated and persistent ER stress supported by CHOP overproduction.     

β-Glucan from Saccharomyces cerevisiae alleviates oxidative stress in LPS-stimulated RAW264.7 cells via Dectin-1/Nrf2/HO-1 signaling pathway

β-Glucan from Saccharomyces cerevisiae has been described to be effective antioxidants, but the specific antioxidation mechanism of β-glucan is unclear. The objectives of this research were to determine whether the β-glucan from Saccharomyces cerevisiae could regulate oxidative stress through the Dectin-1/Nrf2/HO-1 signaling pathway in lipopolysaccharides (LPS)-stimulated RAW264.7 cells. In this study, we examined the effects of β-glucan on the enzyme activity or production of oxidative stress indicators in LPS-stimulated RAW264.7 cells by biochemical analysis and the protein expression of key factors of Dectin-1/Nrf2/HO-1 signaling pathway by immunofluorescence and western blot. The biochemical analysis results showed that β-glucan increased the LPS-induced downregulation of enzyme activity of intracellular heme oxygenase (HO), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) while decreasing the production of reactive oxygen species (ROS) and malondialdehyde (MDA). Furthermore, immunofluorescence results showed that β-glucan can activate the nuclear factor erythroid 2-related factor 2 (Nrf2). The antioxidant mechanism study indicated that β-glucan activated dendritic-cell-associated C-type lectin 1 (Dectin-1) receptors mediated Nrf2/HO-1 signaling pathway, thereby downregulating the production of ROS and thus produced the antioxidant effects in LPS-stimulated RAW 264.7 cells. In conclusion, these results indicate that β-glucan potently alleviated oxidative stress via Dectin-1/Nrf2/HO-1 in LPS-stimulated RAW 264.7 cells.     

Fyn Activation of mTORC1 Stimulates the IRE1α-JNK Pathway,Leading to Cell Death

We previously reported that the skeletal muscle-specific overexpression of Fyn in mice resulted in a severe muscle wasting phenotype despite the activation of mTORC1 signaling. To investigate the bases for the loss of muscle fiber mass, we examined the relationship between Fyn activation of mTORC1, JNK, and endoplasmic reticulum stress. Overexpression of Fyn in skeletal muscle in vivo and in HEK293T cells in culture resulted in the activation of IRE1α and JNK, leading to increased cell death. Fyn synergized with the general endoplasmic reticulum stress inducer thapsigargin, resulting in the activation of IRE1α and further accelerated cell death. Moreover, inhibition of mTORC1 with rapamycin suppressed IRE1α activation and JNK phosphorylation, resulting in protecting cells against Fyn- and thapsigargin-induced cell death. Moreover, rapamycin treatment in vivo reduced the skeletal muscle IRE1α activation in the Fyn-overexpressing transgenic mice. Together, these data demonstrate the presence of a Fyn-induced endoplasmic reticulum stress that occurred, at least in part, through the activation of mTORC1, as well as subsequent activation of the IRE1α-JNK pathway driving cell death.     

Endoplasmic Reticulum Oxidoreductin-1α (Ero1α) Improves Folding and Secretion of Mutant Proinsulin and Limits Mutant Proinsulin-induced Endoplasmic Reticulum Stress

Upon chronic up-regulation of proinsulin synthesis, misfolded proinsulin can accumulate in the endoplasmic reticulum (ER) of pancreatic β-cells, promoting ER stress and type 2 diabetes mellitus. In Mutant Ins-gene-induced Diabetes of Youth (MIDY), misfolded mutant proinsulin impairs ER exit of co-expressed wild-type proinsulin, limiting insulin production and leading to eventual β-cell death. In this study we have investigated the hypothesis that increased expression of ER oxidoreductin-1α (Ero1α), despite its established role in the generation of H₂O₂, might nevertheless be beneficial in limiting proinsulin misfolding and its adverse downstream consequences. Increased Ero1α expression is effective in promoting wild-type proinsulin export from cells co-expressing misfolded mutant proinsulin. In addition, we find that upon increased Ero1α expression, some of the MIDY mutants themselves are directly rescued from ER retention. Secretory rescue of proinsulin-G(B23)V is correlated with improved oxidative folding of mutant proinsulin. Indeed, using three different variants of Ero1α, we find that expression of either wild-type or an Ero1α variant lacking regulatory disulfides can rescue mutant proinsulin-G(B23)V, in parallel with its ability to provide an oxidizing environment in the ER lumen, whereas beneficial effects were less apparent for a redox-inactive form of Ero1. Increased expression of protein disulfide isomerase antagonizes the rescue provided by oxidatively active Ero1. Importantly, ER stress induced by misfolded proinsulin was limited by increased expression of Ero1α, suggesting that enhancing the oxidative folding of proinsulin may be a viable therapeutic strategy in the treatment of type 2 diabetes.     

Heterotrimeric G protein subunits differentially respond to endoplasmic reticulum stress in Arabidopsis

Canonical heterotrimeric G proteins in eukaryotes are major components that localize at plasma membrane and transmit extracellular stimuli into the cell. Genome of a seed plant Arabidopsis thaliana encodes at least one Gα (GPA1), one Gβ (AGB1), and 3 Gγ (AGG1, AGG2 and AGG3) subunits. The loss-of-function mutations of G protein subunit(s) cause multiple defects in development as well as biotic and abiotic stress responses. However, it remains elusive how these subunits differentially express these defects. Here, we report that Arabidopsis heterotrimeric G protein subunits differentially respond to the endoplasmic reticulum (ER) stress. An isolated homozygous mutant of AGB1, agb1-3, was more sensitive to the tunicamycin-induced ER stress compared to the wild type and the other loss-of-function mutants of G protein subunits. Moreover, ER stress responsive genes were highly expressed in the agb1-3 plant. Our results indicate that AGB1 positively contributes to ER stress tolerance in Arabidopsis.     

Neuraminidase 1 deficiency attenuates cardiac dysfunction,oxidative stress,fibrosis, inflammatory via AMPK-SIRT3 pathway in diabetic cardiomyopathy mice

Diabetic cardiomyopathy (DCM) is associated with oxidative stress and augmented inflammation in the heart. Neuraminidases (NEU) 1 has initially been described as a lysosomal protein which plays a role in the catabolism of glycosylated proteins. We investigated the role of NEU1 in the myocardium in diabetic heart. Streptozotocin (STZ) was injected intraperitoneally to induce diabetes in mice. Neonatal rat ventricular myocytes (NRVMs) were used to verify the effect of shNEU1 in vitro. NEU1 is up-regulated in cardiomyocytes under diabetic conditions. NEU1 inhibition alleviated oxidative stress, inflammation and apoptosis, and improved cardiac function in STZ-induced diabetic mice. Furthermore, NEU1 inhibition also attenuated the high glucose-induced increased reactive oxygen species generation, inflammation and, cell death in vitro. ShNEU1 activated Sirtuin 3 (SIRT3) signaling pathway, and SIRT3 deficiency blocked shNEU1-mediated cardioprotective effects in vitro. More importantly, we found AMPKα was responsible for the elevation of SIRT3 expression via AMPKα-deficiency studies in vitro and in vivo. Knockdown of LKB1 reversed the effect elicited by shNEU1 in vitro. In conclusion, NEU1 inhibition activates AMPKα via LKB1, and subsequently activates sirt3, thereby regulating fibrosis, inflammation, apoptosis and oxidative stress in diabetic myocardial tissue.     

Role of protein kinase C δ in ER stress and apoptosis induced by oxidized LDL in human vascular smooth muscle cells

During atherogenesis, excess amounts of low-density lipoproteins (LDL) accumulate in the subendothelial space where they undergo oxidative modifications. Oxidized LDL (oxLDL) alter the fragile balance between survival and death of vascular smooth muscle cells (VSMC) thereby leading to plaque instability and finally to atherothrombotic events. As protein kinase C δ (PKCδ) is pro-apoptotic in many cell types, we investigated its potential role in the regulation of VSMC apoptosis induced by oxLDL. We found that human VSMC silenced for PKCδ exhibited a protection towards oxLDL-induced apoptosis. OxLDL triggered the activation of PKCδ as shown by its phosphorylation and nuclear translocation. PKCδ activation was dependent on the reactive oxygen species generated by oxLDL. Moreover, we demonstrated that PKCδ participates in oxLDL-induced endoplasmic reticulum (ER) stress-dependent apoptotic signaling mainly through the IRE1α/JNK pathway. Finally, the role of PKCδ in the development of atherosclerosis was supported by immunohistological analyses showing the colocalization of activated PKCδ with ER stress and lipid peroxidation markers in human atherosclerotic lesions. These findings highlight a role for PKCδ as a key regulator of oxLDL-induced ER stress-mediated apoptosis in VSMC, which may contribute to atherosclerotic plaque instability and rupture.     

Endoplasmic reticulum stress sensitizes pancreatic beta cells to interleukin-1β-induced apoptosis via Bim/A1 imbalance

We have recently shown that the crosstalk between mild endoplasmic reticulum (ER) stress and low concentrations of the pro-inflammatory cytokine interleukin (IL)-1β exacerbates beta cell inflammatory responses via the IRE1α/XBP1 pathway. We presently investigated whether mild ER stress also sensitizes beta cells to cytokine-induced apoptosis. Cyclopiazonic acid (CPA)-induced ER stress enhanced the IL-1β apoptosis in INS-1E and primary rat beta cells. This was not prevented by XBP1 knockdown (KD), indicating the dissociation between the pathways leading to inflammation and cell death. Analysis of the role of pro- and anti-apoptotic proteins in cytokine-induced apoptosis indicated a central role for the pro-apoptotic BH3 (Bcl-2 homology 3)-only protein Bim (Bcl-2-interacting mediator of cell death), which was counteracted by four anti-apoptotic Bcl-2 (B-cell lymphoma-2) proteins, namely Bcl-2, Bcl-XL, Mcl-1 and A1. CPA+IL-1β-induced beta cell apoptosis was accompanied by increased expression of Bim, particularly the most pro-apoptotic variant, small isoform of Bim (Bim_S), and decreased expression of A1. Bim silencing protected against CPA+IL-1β-induced apoptosis, whereas A1 KD aggravated cell death. Bim inhibition protected against cell death caused by A1 silencing under all conditions studied. In conclusion, mild ER stress predisposes beta cells to the pro-apoptotic effects of IL-1β by disrupting the balance between pro- and anti-apoptotic Bcl-2 proteins. These findings link ER stress to exacerbated apoptosis during islet inflammation and provide potential mechanistic targets for beta cell protection, namely downregulation of Bim and upregulation of A1.     

Polyphenol oxidase-mediated protection against oxidative stress is not associated with enhanced photosynthetic efficiency

Background and Aims Polyphenol oxidases (PPOs) catalyse the oxidation of monophenols and/or o-diphenols to highly reactive o-quinones, which in turn interact with oxygen and proteins to form reactive oxygen species (ROS) and typical brown-pigmented complexes. Hence PPOs can affect local levels of oxygen and ROS. Although the currently known substrates are located in the vacuole, the enzyme is targeted to the thylakoid lumen, suggesting a role for PPOs in photosynthesis. The current study was designed to investigate the potential involvement of PPOs in the photosynthetic response to oxidative stress.Methods Photosynthesis (A, F_v/F_m, ΦPSII, q_N, q_P, NPQ) was measured in leaves of a wild-type and a low-PPO mutant of red clover (Trifolium pratense ‘Milvus’) under control conditions and under a stress treatment designed to induce photooxidative stress: cold/high light (2 °C/580 µmol m²s^–1) or 0–10 µm methyl viologen. Foliar protein content and oxidation state were also determined.Key Results Photosynthetic performance, and chlorophyll and protein content during 4 d of cold/high light stress and 3 d of subsequent recovery under control growth conditions showed similar susceptibility to stress in both lines. However, more extensive oxidative damage to protein in mutants than wild-types was observed after treatment of attached leaves with methyl viologen. In addition, PPO activity could be associated with an increased capacity to dissipate excess energy, but only at relatively low methyl viologen doses.Conclusions The presence of PPO activity in leaves did not correspond to a direct role for the enzyme in the regulation or protection of photosynthesis under cold stress. However, an indication that PPO could be involved in cellular protection against low-level oxidative stress requires further investigation.     

The HSP GRP94 interacts with macrophage intracellular complement C3 and impacts M2 profile during ER stress

The role of GRP94, an endoplasmic reticulum (ER) stress protein with both pro- and anti-inflammatory functions, has not been investigated in macrophages during ER stress, whereas ER stress has been reported in many diseases involving macrophages. In this work, we studied GRP94 in M1/LPS + IFNγ and M2/IL-4 primary macrophages derived from human monocytes (isolated from buffy coats), in basal and ER stress conditions induced by thapsigargin (Tg), an inducer of ER calcium depletion and tunicamycin (Tm), an inhibitor of N-glycosylation. We found that GRP94 was expressed on the membrane of M2 but not M1 macrophages. In M2, Tg, but not Tm, while decreased GRP94 content in the membrane, it induced its secretion. This correlated with the induction of a pro-inflammatory profile, which was dependent on the UPR IRE1α arm activation and on a functional GRP94. As we previously reported that GRP94 associated with complement C3 at the extracellular level, we analyzed C3 and confirmed GRP94-C3 interaction in our experimental model. Further, Tg increased this interaction and, in these conditions, C3b and cathepsin L were detected in the extracellular medium where GRP94 co-immunoprecipitated with C3 and C3b. Finally, we showed that the C3b inactivated fragment, iC3b, only present on non-stressed M2, depended on functional GRP94, making both GRP94 and iC3b potential markers of M2 cells. In conclusion, our results show that GRP94 is co-secreted with C3 under ER stress conditions which may facilitate its cleavage by cathepsin L, thus contributing to the pro-inflammatory profile observed in stressed M2 macrophages.Subject terms: Immunology, Innate immune cells     

The AKT modulator A-443654 reduces α-synuclein expression and normalizes ER stress and autophagy

Accumulation of α-synuclein is a main underlying pathological feature of Parkinson’s disease and α-synucleinopathies, for which lowering expression of the α-synuclein gene (SNCA) is a potential therapeutic avenue. Using a cell-based luciferase reporter of SNCA expression we performed a quantitative high-throughput screen of 155,885 compounds and identified A-443654, an inhibitor of the multiple functional kinase AKT, as a potent inhibitor of SNCA. HEK-293 cells with CAG repeat expanded ATXN2 (ATXN2-Q58 cells) have increased levels of α-synuclein. We found that A-443654 normalized levels of both SNCA mRNA and α-synuclein monomers and oligomers in ATXN2-Q58 cells. A-443654 also normalized levels of α-synuclein in fibroblasts and iPSC-derived dopaminergic neurons from a patient carrying a triplication of the SNCA gene. Analysis of autophagy and endoplasmic reticulum stress markers showed that A-443654 successfully prevented α-synuclein toxicity and restored cell function in ATXN2-Q58 cells, normalizing the levels of mTOR, LC3-II, p62, STAU1, BiP, and CHOP. A-443654 also decreased the expression of DCLK1, an inhibitor of α-synuclein lysosomal degradation. Our study identifies A-443654 and AKT inhibition as a potential strategy for reducing SNCA expression and treating Parkinson’s disease pathology.     

A Combined “Omics” Approach Identifies N-Myc Interactor as a Novel Cytokine-induced Regulator of IRE1α Protein and c-Jun N-terminal Kinase in Pancreatic Beta Cells

Type 1 diabetes is an autoimmune disease with a strong inflammatory component. The cytokines interleukin-1β and interferon-γ contribute to beta cell apoptosis in type 1 diabetes. These cytokines induce endoplasmic reticulum stress and the unfolded protein response (UPR), contributing to the loss of beta cells. IRE1α, one of the UPR mediators, triggers insulin degradation and inflammation in beta cells and is critical for the transition from “physiological” to “pathological” UPR. The mechanisms regulating inositol-requiring protein 1α (IRE1α) activation and its signaling for beta cell “adaptation,” “stress response,” or “apoptosis” remain to be clarified. To address these questions, we combined mammalian protein-protein interaction trap-based IRE1α interactome and functional genomic analysis of human and rodent beta cells exposed to pro-inflammatory cytokines to identify novel cytokine-induced regulators of IRE1α. Based on this approach, we identified N-Myc interactor (NMI) as an IRE1α-interacting/modulator protein in rodent and human pancreatic beta cells. An increased expression of NMI was detected in islets from nonobese diabetic mice with insulitis and in rodent or human beta cells exposed in vitro to the pro-inflammatory cytokines interleukin-1β and interferon-γ. Detailed mechanistic studies demonstrated that NMI negatively modulates IRE1α-dependent activation of JNK and apoptosis in rodent and human pancreatic beta cells. In conclusion, by using a combined omics approach, we identified NMI induction as a novel negative feedback mechanism that decreases IRE1α-dependent activation of JNK and apoptosis in cytokine-exposed beta cells.     

Bee venom ameliorates cardiac dysfunction in diabetic hyperlipidemic rats

High levels of blood glucose and lipids are well-known risk factors for heart diseases. Bee venom is a natural product that has a potent hypoglycemic, hypolipidemic, anti-inflammatory, and antioxidant effects. The current study aimed to determine the bee venom effects on cardiac dysfunction compared to combined therapy of metformin and atorvastatin in diabetic hyperlipidemic rats. The median lethal dose of bee venom was estimated, and then 50 adult male albino rats were categorized into five groups. One group was fed a standard diet and served as a negative control, while the other groups were given nicotinamide and streptozotocin injections to induce type 2 diabetes. After confirming diabetes, the rats were fed a high-fat diet for four weeks. The four groups were divided as follows: one group served as a positive control, whereas the other three groups were treated with bee venom (0.5 mg/kg), bee venom (1.23 mg/kg), and combined therapy of metformin (60 mg/kg) and atorvastatin (10 mg/kg), respectively, for four weeks. Upon termination of the experiment, blood samples and heart tissue were obtained. Administration of bee venom using both doses (0.5 and 1.23 mg/kg) and combined therapy of metformin and atorvastatin revealed a significant decrease in the concentrations of glucose, total cholesterol, triacylglycerol, low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol, troponin I, creatine kinase, and lactate dehydrogenase activities. Moreover, a significant decrease had been detedcted in malondialdehyde, nuclear factor-kappa-β levels, and relative mRNA expression of vascular cell adhesion molecule-1 and galectin-3 in heart tissue compared to the positive control (P < 0.0001). Furthermore, there was a significant increase in bodyweight levels of insulin, high-density lipoprotein cholesterol, and total antioxidant capacity in heart tissue compared to the positive control (P < 0.0001). The results indicate that bee venom can ameliorate cardiac dysfunction through attenuating oxidative stress and downregulating the NF-κβ signaling pathway.     

Sleepiness,inflammation and oxidative stress markers in middle-aged males with obstructive sleep apnea without metabolic syndrome: a cross-sectional study

Background

The simultaneous occurrence of metabolic syndrome and excessive daytime sleepiness are very common in obstructive sleep apnea (OSA) patients. Both conditions, if present in OSA, have been reported to be associated with inflammation and disruption of oxidative stress balance that impair the cardiovascular system. To verify the impact of daytime sleepiness on inflammatory and oxidative stress markers, we evaluated OSA patients without significant metabolic disturbance.

Methods

Thirty-five male subjects without diagnostic criteria for metabolic syndrome (Adult Treatment Panel III) were distributed into a control group (n = 10) (43 ± 10.56 years, apnea-hypopnea index - AHI 2.71 ± 1.48/hour), a non-sleepy OSA group (n = 11) (42.36 ± 9.48 years, AHI 29.48 ± 22.83/hour) and a sleepy OSA group (n = 14) (45.43 ± 10.06 years, AHI 38.20 ± 25.54/hour). Excessive daytime sleepiness was considered when Epworth sleepiness scale score was ≥ 10. Levels of high-sensitivity C-reactive protein, homocysteine and cysteine, and paraoxonase-1 activity and arylesterase activity of paraoxonase-1 were evaluated.

Results

Patients with OSA and excessive daytime sleepiness presented increased high-sensitivity C-reactive protein levels even after controlling for confounders. No significant differences were found among the groups in paraoxonase-1 activity nor arylesterase activity of paraoxonase-1. AHI was independently associated and excessive daytime sleepiness tended to have an association with high-sensitivity C-reactive protein.

Conclusions

In the absence of metabolic syndrome, increased inflammatory response was associated with AHI and daytime sleepiness, while OSA was not associated with abnormalities in oxidative stress markers.     

Cannabidiol protects oligodendrocyte progenitor cells from inflammation-induced apoptosis by attenuating endoplasmic reticulum stress

Cannabidiol (CBD) is the most abundant cannabinoid in Cannabis sativa that has no psychoactive properties. CBD has been approved to treat inflammation, pain and spasticity associated with multiple sclerosis (MS), of which demyelination and oligodendrocyte loss are hallmarks. Thus, we investigated the protective effects of CBD against the damage to oligodendrocyte progenitor cells (OPCs) mediated by the immune system. Doses of 1 μM CBD protect OPCs from oxidative stress by decreasing the production of reactive oxygen species. CBD also protects OPCs from apoptosis induced by LPS/IFNγ through the decrease of caspase 3 induction via mechanisms that do not involve CB1, CB2, TRPV1 or PPARγ receptors. Tunicamycin-induced OPC death was attenuated by CBD, suggesting a role of endoplasmic reticulum (ER) stress in the mode of action of CBD. This protection against ER stress-induced apoptosis was associated with reduced phosphorylation of eiF2α, one of the initiators of the ER stress pathway. Indeed, CBD diminished the phosphorylation of PKR and eiF2α induced by LPS/IFNγ. The pro-survival effects of CBD in OPCs were accompanied by decreases in the expression of ER apoptotic effectors (CHOP, Bax and caspase 12), and increased expression of the anti-apoptotic Bcl-2. These findings suggest that attenuation of the ER stress pathway is involved in the ‘oligoprotective'' effects of CBD during inflammation.