C-reactive protein promotes adhesion of monocytes to endothelial cells via NADPH oxidase-mediated oxidative stress

Role of Oxidative Stress in Ocular Diseases: A Balancing Act

Redox homeostasis is a delicate balancing act of maintaining appropriate levels of antioxidant defense mechanisms and reactive oxidizing oxygen and nitrogen species. Any disruption of this balance leads to oxidative stress, which is a key pathogenic factor in several ocular diseases. In this review, we present the current evidence for oxidative stress and mitochondrial dysfunction in conditions affecting both the anterior segment (e.g., dry eye disease, keratoconus, cataract) and posterior segment (age-related macular degeneration, proliferative vitreoretinopathy, diabetic retinopathy, glaucoma) of the human eye. We posit that further development of therapeutic interventions to promote pro-regenerative responses and maintenance of the redox balance may delay or prevent the progression of these major ocular pathologies. Continued efforts in this field will not only yield a better understanding of the molecular mechanisms underlying the pathogenesis of ocular diseases but also enable the identification of novel druggable redox targets and antioxidant therapies.

Crossmodal Audiovisual Emotional Integration in Depression: An Event-Related Potential Study

Depression is related to the defect of emotion processing, and people's emotional processing is crossmodal. This article aims to investigate whether there is a difference in audiovisual emotional integration between the depression group and the normal group using a high-resolution event-related potential (ERP) technique. We designed a visual and/or auditory detection task. The behavioral results showed that the responses to bimodal audiovisual stimuli were faster than those to unimodal auditory or visual stimuli, indicating that crossmodal integration of emotional information occurred in both the depression and normal groups. The ERP results showed that the N2 amplitude induced by sadness was significantly higher than that induced by happiness. The participants in the depression group showed larger amplitudes of N1 and P2, and the average amplitude of LPP evoked in the frontocentral lobe in the depression group was significantly lower than that in the normal group. The results indicated that there are different audiovisual emotional processing mechanisms between depressed and non-depressed college students.

Effects of hyperhomocysteinemia on ischemic cerebral small vessel disease and analysis of inflammatory mechanisms

Purpose: Hyperhomocysteinemia is closely related to, but is not a confirmed risk factor of, cerebral small vessel disease (CSVD). This study aimed to determine whether hyperhomo-cysteinemia is correlated significantly with CSVD.Materials and methods: This cross-sectional study compared the homocysteine (Hcy) levels of patients with and without CSVD. High-sensitivity C-reactive protein (hs-CRP) levels were compared according to white matter lesion (WML) severity, which was classified using the Fazekas system. Risk factors for ischemic CSVD were analyzed through multivariate unconditional logistic regression analysis.Results: Hcy levels were significantly higher in patients with lacunar infarction (LI) than in controls (p=.0438), in patients with Fazekas 2-3 than in patients with Fazekas 0-1 WMLs (p=.0192), in patients with Fazekas 4-6 than in patients with Fazekas 2-3 WMLs (p=.0207), and in patients with LI than in patients without LI (p=.0043). hs-CRP levels were significantly higher in patients with LI than in patients without LI (p=.0068) and in patients with Fazekas 4-6 than in patients with Fazekas 0-1 WMLs (p=.0031). Three multivariate unconditional logistic regression analyses showed that hyperhomocysteinemia is a risk factor for LI (p=.006; odds ratio [OR], 27.668), severe WML (p=.028; OR, 1.984), and high hs-CRP level (p=.016; OR, 3.956).Conclusions: The assessment of Hcy levels is important for ischemic CSVD. Hyperhomocysteinemia is a risk factor for LI and severe WML. Further, hyperhomocysteinemia is associated with high hs-CRP levels, and this may involve an inflammatory mechanism; however, further studies are needed in this regard.

Hydrogen Sulfide Protects Against High Glucose-Induced Human Umbilical Vein Endothelial Cell Injury Through Activating PI3K/Akt/eNOS Pathway

Purpose

Dysfunction of endothelial cells plays a key role in the pathogenesis of diabetic atherosclerosis. High glucose (HG) has been found as a key factor in the progression of diabetic complications, including atherosclerosis. PI3K/Akt/eNOS signaling pathway has been shown to involve in HG-induced vascular injuries. Hydrogen sulfide (H₂S) has been found to exhibit protective effects on HG-induced vascular injuries. Moreover, H₂S activates PI3K/Akt/eNOS pathway in endothelial cells. Thus, the present study aimed to determine if H₂S exerts protective effects against HG-induced injuries of human umbilical vein endothelial cells (HUVECs) via activating PI3K/Akt/eNOS signaling.

Materials and Methods

The endothelial protective effects of H₂S were evaluated and compared to the controlled groups. Cell viability, cell migration and tube formation were determined by in vitro functional assays; protein levels were evaluated by Western blot assay and ELISA; cell apoptosis was determined by Hoechst 33258 nuclear staining; Reactive oxygen species (ROS) production was evaluated by the ROS detection kit.

Results

HG treatment significantly inhibited PI3K/Akt/eNOS signaling in HUVECs, which was partially reversed by the H2S treatment. HG treatment inhibited cell viability of HUVECs, which were markedly prevented by H₂S or PI3K agonist Y-P 740. HG treatment also induced HUVEC cell apoptosis by increasing the protein levels of cleaved caspase 3, Bax and Bcl-2, which were significantly attenuated by H₂S or 740 Y-P. ROS production and gp91^phox protein level were increased by HG treatment in HUVECs and this effect can be blocked by the treatment with H₂S or Y-P 740. Moreover, HG treatment increased the protein levels of pro-inflammatory cytokines, caspase-1 and phosphorylated JNK, which was significantly attenuated by H₂S or Y-P 740. Importantly, the cytoprotective effect of H₂S against HG-induced injury was inhibited by LY294002 (an inhibitor of PI3K/Akt/eNOS signaling pathway).

Conclusion

The present study demonstrated that exogenous H₂S protects endothelial cells against HG-induced injuries by activating PI3K/Akt/eNOS pathway. Based on the above findings, we proposed that reduced endogenous H₂S levels and the subsequent PI3K/Akt/eNOS signaling impairment may be the important pathophysiological mechanism underlying hyperglycemia-induced vascular injuries.

Impact of C-reactive protein on osteo-/chondrogenic transdifferentiation and calcification of vascular smooth muscle cells

Medial vascular calcification occurs during the aging process and is strongly accelerated by chronic kidney disease (CKD). Elevated C-reactive protein (CRP) levels are associated with vascular calcification, cardiovascular events and mortality in CKD patients. CRP is an important promoter of vascular inflammation. Inflammatory processes are critically involved in initiation and progression of vascular calcification. Thus, the present study explored a possible impact of CRP on vascular calcification. We found that CRP promoted osteo-/chondrogenic transdifferentiation and aggravated phosphate-induced osteo-/chondrogenic transdifferentiation and calcification of primary human aortic smooth muscle cells (HAoSMCs). These effects were paralleled by increased cellular oxidative stress and corresponding pro-calcific downstream-signaling. Antioxidants or p38 MAPK inhibition suppressed CRP-induced osteo-/chondrogenic signaling and mineralization. Furthermore, silencing of Fc fragment of IgG receptor IIa (FCGR2A) blunted the pro-calcific effects of CRP. Vascular CRP expression was increased in the klotho-hypomorphic mouse model of aging as well as in HAoSMCs during calcifying conditions. In conclusion, CRP augments osteo-/chondrogenic transdifferentiation of vascular smooth muscle cells through mechanisms involving FCGR2A-dependent induction of oxidative stress. Thus, systemic inflammation may actively contribute to the progression of vascular calcification.

Reduced Plasma Kallistatin Is Associated With the Severity of Coronary Artery Disease, and Kallistatin Treatment Attenuates Atherosclerotic Plaque Formation in Mice

Background Kallistatin exerts beneficial effects on organ injury by inhibiting oxidative stress and inflammation. However, the role of kallistatin in atherosclerosis is largely unknown. Here, we investigated the role and mechanisms of kallistatin in patients with coronary artery disease ( CAD ), atherosclerotic plaques of apoE-/- mice, and endothelial activation. Methods and Results Plasma kallistatin levels were analyzed in 453 patients at different stages of CAD . Kallistatin levels were significantly lower in patients with CAD and negatively associated with CAD severity and oxidative stress. Human kallistatin cDNA in an adenoviral vector was injected intravenously into apoE-/- mice after partial carotid ligation, with or without nitric oxide synthase inhibitor (Nω-nitro-L-arginine methyl ester) or sirtuin 1 inhibitor (nicotinamide). Kallistatin gene delivery significantly reduced macrophage deposition, oxidative stress, and plaque volume in the carotid artery, compared with control adenoviral injection. Kallistatin administration increased endothelial nitrous oxide synthase, sirtuin 1, interleukin-10, superoxide dismutase 2, and catalase expression in carotid plaques. The beneficial effects of kallistatin in mice were mitigated by Nω-nitro-L-arginine methyl ester or nicotinamide. Furthermore, human kallistatin protein suppressed tumor necrosis factor-α-induced NADPH oxidase activity and increased endothelial nitrous oxide synthase and sirtuin 1 expression in cultured human endothelial cells. These effects were also abolished by Nω-nitro-L-arginine methyl ester or nicotinamide. Conclusions This was the first study to demonstrate that reduced plasma kallistatin levels in patients are associated with CAD severity and oxidative stress. Kallistatin treatment prevents carotid atherosclerotic plaque formation in mice by stimulating the sirtuin 1/endothelial nitrous oxide synthase pathway. These findings indicate the potential protective effects of kallistatin on atherosclerosis in human subjects and mouse models.

High-dose atorvastatin versus moderate dose on early vascular protection after ST-elevation myocardial infarction

Background and aim

Clinical benefits of early high-dose statin therapy after acute coronary syndromes are widely known; however, there is poor evidence on the specific setting of ST-elevation myocardial infarction (STEMI) and dose-dependent effects of this therapy on endothelial function and inflammatory biomarkers in the most vulnerable phase after acute coronary syndromes: the postdischarge period. In our study, we compared the short-term effects of high (80 mg) vs moderate doses of atorvastatin (20 mg) in patients with STEMI undergoing primary percutaneous coronary intervention on endothelial function and vascular inflammation. The aim of our study was the evaluation of dose-dependent short-term effects.

Subjects and methods

We enrolled 52 patients within 48 hours of a STEMI to atorvastatin 80 mg (n=26) or 20 mg (n=26). Every patient underwent endothelial function evaluation by the reactive hyperemia–peripheral arterial tonometry (RH-PAT) index on the first day and 1 month after the STEMI. At the same time, we measured lipid profile and serum levels of high-sensitivity CRP, IL6, TNFα, and oxidized LDL.

Results

After 1 month of therapy, we observed differences in high-sensitivity CRP levels (0.04±0.02 mg/dL vs 0.36±0.3 mg/dL, P=0.001), IL6 (1.12±0.93 pg/mL vs 3.13±2.84 pg/mL, P=0.03), and improvement in RH-PAT index (1.96±0.16 vs 1.72±0.19, P=0.002) in the group treated with high-dose vs moderate-dose atorvastatin. There was no significant difference in levels of TNFα or oxidized LDL with atorvastatin 20 mg, while there was a reduction in these variables in the group treated with atorvastatin 80 mg. We observed a correlation between high-sensitivity polymerase chain reaction and RH-PAT index on the 30th day after STEMI (r=0.5, P=0.001).

Conclusion

Higher dose statin therapy in patients with STEMI undergoing primary percutaneous coronary intervention showed early greater vascular protective effects that moderate dose.

GLP-1 Inhibits High-Glucose-Induced Oxidative Injury of Vascular Endothelial Cells

The aim of this work was to evaluate the effects of glucagon-like peptide-1 (GLP-1) on high-glucose-induced oxidative stress and investigate the possible mechanisms underlying this process. We measured reactive oxygen species (ROS) production, cell apoptosis, the expression of NOX4 and its subunits, and p47phox translocation in human umbilical vein endothelial cells (HUVECs). An experimental type 2 diabetes model was induced using streptozotocin in male Sprague-Dawley rats. Fasting blood glucose (FBG), fasting insulin (FINS), total cholesterol (TC), triglycerides (TGs), and free fatty acid (FFA) were measured. Histomorphological analysis of the aorta was performed using hematoxylin-eosin staining. NOX4 and VCAM-1 expression in the aorta was measured. We found that high-glucose-induced ROS production and apoptosis were inhibited by GLP-1 treatment. High glucose caused upregulation of NOX4, p47phox, and Rac-1 and translocation of p47phox but had no effect on the cells pretreated with GLP-1. Furthermore, in the diabetic group, FBG, FINS, TG, TC, and FFA were increased, and NOX4 and VCAM-1 levels were also elevated. However, GLP-1 attenuated all these changes. GLP-1 ameliorated high-glucose-induced oxidative stress by inhibiting NOX4, p47phox, and Rac-1 expression and translocation of p47phox, suggesting its clinical usefulness in diabetic vascular complications.

Reactive Oxygen Species: A Key Hallmark of Cardiovascular Disease

Cardiovascular diseases (CVDs) have been the prime cause of mortality worldwide for decades. However, the underlying mechanism of their pathogenesis is not fully clear yet. It has been already established that reactive oxygen species (ROS) play a vital role in the progression of CVDs. ROS are chemically unstable reactive free radicals containing oxygen, normally produced by xanthine oxidase, nicotinamide adenine dinucleotide phosphate oxidase, lipoxygenases, or mitochondria or due to the uncoupling of nitric oxide synthase in vascular cells. When the equilibrium between production of free radicals and antioxidant capacity of human physiology gets altered due to several pathophysiological conditions, oxidative stress is induced, which in turn leads to tissue injury. This review focuses on pathways behind the production of ROS, its involvement in various intracellular signaling cascades leading to several cardiovascular disorders (endothelial dysfunction, ischemia-reperfusion, and atherosclerosis), methods for its detection, and therapeutic strategies for treatment of CVDs targeting the sources of ROS. The information generated by this review aims to provide updated insights into the understanding of the mechanisms behind cardiovascular complications mediated by ROS.

Intensive Statin Therapy in NSTE-ACS Patients Undergoing PCI: Clinical and Biochemical Effects

Early initiation of statin therapy in acute coronary syndrome patients has a favorable prognostic impact because of its anti-inflammatory and antithrombotic properties. In this study, we explored the effect of atorvastatin-loading, followed by intensive atorvastatin therapy, on clinical and biochemical outcomes in non-ST-segment-elevation acute coronary syndrome patients who were scheduled for percutaneous coronary intervention. We prospectively enrolled 140 patients (mean age, 56 ± 9 years, 68% men). Once eligible, patients were randomly assigned to receive either a moderate 20-mg daily dose of atorvastatin (Group A) or a 160-mg loading dose followed by an intensified 80-mg daily dose (Group B). High-sensitivity C-reactive protein (hs-CRP) levels were recorded before and after intervention. Evaluation after 6 months included hs-CRP levels, left ventricular systolic function, and major adverse cardiac events. We found no significant difference between the 2 groups in regard to the interventional data. However, blood sampling after coronary intervention, and again 6 months later, revealed a significant decline in mean hs-CRP level among Group B patients (P < 0.001). Moreover, patients in Group B manifested a higher left ventricular ejection fraction than did patients in Group A (P < 0.05). After 6 months, we found no significant difference between groups in the incidence of major adverse cardiac events. We conclude that intensive atorvastatin therapy in non-ST-segment-elevation acute coronary syndrome patients is associated with lower hs-CRP levels and with higher left ventricular ejection fraction after 6 months, with no significant impact on adverse cardiac events.

Correlation between serum levels of C-reactive protein and infant pneumonia: A meta-analysis

Experimental data imply that serum C-reactive protein (CRP) is a marker of general systemic inflammation, and inflammation may have a role in the development of pneumonia. The aim of the present study was to investigate the associations of serum CRP levels in infant patients with pneumonia by meta-analysis. The Science Citation Index, Cochrane Library, PubMed, Embase, CINAHL, Current Contents and two Chinese (CMB and CNKI) databases were searched. Studies were pooled and standard mean difference (SMD) and the corresponding 95% confidence interval (CI) were calculated. Subgroup analyses and publication bias detection were also conducted. The statistical analysis was conducted using Stata software version 12.0. Serum CRP levels were analyzed in 10 clinical case-control studies (652 infants with pneumonia and 845 healthy controls); significant differences in serum CRP levels were observed between infants with pneumonia and the healthy controls (SMD=4.41, 95% CI: 3.34-5.47, P<0.001). Ethnicity-stratified subgroup analysis detected that high levels of serum CRP may be the main risk factor for infant pneumonia in Asian, African and Caucasian populations (all P<0.05). Serum CRP levels were statistically higher in infants with pneumonia than in healthy infants, and thus serum levels of CRP may have independent diagnostic value for pneumonia in children.

C-reactive protein stimulates RAGE expression in human coronary artery endothelial cells in vitro via ROS generation and ERK/NF-κB activation

AIM

The receptor for advanced glycation end-products (RAGE) plays an important role in development of atherosclerosis, and C-reactive protein (CRP) has been found to stimulate its expression in endothelial cells. In this study we investigated how CRP regulated the expression of RAGE in human coronary artery endothelial cells (HCAECs).

METHODS

HCAECs were treated in vitro with CRP (50 μg/mL) in combination with a variety of inhibitors. ROS generation was determined by immunocytochemistry and flow cytometry. The RAGE expression and phosphorylation of relevant signaling proteins were measured using Western blot analyses.

RESULTS

CRP stimulated the expression of RAGE in the cells, accompanied by markedly increased ROS generation, phosphorylation of ERK1/2 and NF-κB p65, as well as translocation of NF-κB p65 to the nuclei. CRP also stimulated phosphorylation of JNK and p38 MAPK. Pretreatment of the cells with the ROS scavenger N-acetyl-L-cysteine, ERK inhibitor PD98059 or NF-κB inhibitor PDTC blocked CRP-stimulated RAGE expression, but pretreatment with the NADPH oxidase inhibitor DPI, JNK inhibitor SP600125 or p38 MAPK inhibitor SB203580 did not significantly alter CRP-stimulated RAGE expression.

CONCLUSION

CRP stimulates RAGE expression in HCAECs in vitro via ROS generation and activation of the ERK/NF-κB signaling pathway.

High glucose induced oxidative stress and apoptosis in cardiac microvascular endothelial cells are regulated by FoxO3a

Aim

Cardiac microvascular endothelial cells (CMECs) dysfunction contributes to cardiovascular complications in diabetes, whereas, the underlying mechanism is not fully clarified. FoxO transcription factors are involved in apoptosis and reactive oxygen species (ROS) production. Therefore, the present study was designed to elucidate the potential role of FoxO3a on the CMECs injury induced by high glucose.

Materials and Methods

CMECs were isolated from hearts of adult rats and cultured in normal or high glucose medium for 6 h, 12 h and 24 h respectively. To down-regulate FoxO3a expression, CMECs were transfected with FoxO3a siRNA. ROS accumulation and apoptosis in CMECs were assessed by dihydroethidine (DHE) staining and TUNEL assay respectively. Moreover, the expressions of Akt, FoxO3a, Bim and BclxL in CMECs were assessed by Western blotting assay.

Results

ROS accumulation in CMECs was significantly increased after high glucose incubation for 6 to 24 h. Meanwhile, high glucose also increased apoptosis in CMECs, correlated with decreased the phosphorylation expressions of Akt and FoxO3a. Moreover, high glucose incubation increased the expression of Bim, whereas increased anti-apoptotic protein BclxL. Furthermore, siRNA target FoxO3a silencing enhanced the ROS accumulation, whereas suppressed apoptosis in CMECs. FoxO3a silencing also abolished the disturbance of Bcl-2 proteins induced by high glucose in CMECs.

Conclusion

Our data provide evidence that high glucose induced FoxO3a activation which suppressed ROS accumulation, and in parallel, resulted in apoptosis of CMECs.

Proteomic analysis identifies an NADPH oxidase 1 (Nox1)-mediated role for actin-related protein 2/3 complex subunit 2 (ARPC2) in promoting smooth muscle cell migration

A variety of vascular pathologies, including hypertension, restenosis and atherosclerosis, are characterized by vascular smooth muscle cell (VSMC) hypertrophy and migration. NADPH oxidase 1 (Nox1) plays a pivotal role in these phenotypes via distinct downstream signaling. However, the mediators differentiating these distinct phenotypes and their precise role in vascular disease are still not clear. The present study was designed to identify novel targets of VSMC Nox1 signaling using 2D Differential In-Gel Electrophoresis and Mass Spectrometry (2D-DIGE/MS). VSMC treatment with scrambled (Scrmb) or Nox1 siRNA and incubation with the oxidant hydrogen peroxide (H₂O₂; 50 μM, 3 h) followed by 2D-DIGE/MS on cell lysates identified 10 target proteins. Among these proteins, actin-related protein 2/3 complex subunit 2 (ARPC2) with no previous link to Nox isozymes, H₂O₂, or other reactive oxygen species (ROS), was identified and postulated to play an intermediary role in VSMC migration. Western blot confirmed that Nox1 mediates H₂O₂-induced ARPC2 expression in VSMC. Treatment with a p38 MAPK inhibitor (SB203580) resulted in reduced ARPC2 expression in H₂O₂-treated VSMC. Additionally, wound-healing “scratch” assay confirmed that H₂O₂ stimulates VSMC migration via Nox1. Importantly, gene silencing of ARPC2 suppressed H₂O₂-stimulated VSMC migration. These results demonstrate for the first time that Nox1-mediated VSMC migration involves ARPC2 as a downstream signaling target.

Positive association between high-sensitivity C-reactive protein and incidence of type 2 diabetes mellitus in Japanese workers: 6-year follow-up

BACKGROUND

Elevated high-sensitivity C-reactive protein (hs-CRP), a marker of low-grade systemic inflammation, may be involved in the etiology of type 2 diabetes mellitus (T2DM). However, whether inflammation precedes development of T2DM independent of cigarette smoking and obesity remains to be confirmed.

METHODS

We studied 4213 civil servants in a local government in Japan aged 35-66 years at baseline in 2002, who donated blood samples and were followed 6 years. Hazard ratios (HR) of T2DM according to the hs-CRP quartiles [range Q1: 0.02-0.18 (reference), Q2: 0.18-0.33, Q3: 0.33-0.67 and Q4: 0.67-9.62 mg/L) were estimated by Cox proportional hazards model adjusted for gender, age, body mass index, alcohol intake, smoking status (current, past and never), number of cigarettes per day, physical activity, family history of diabetes (Model 1) and variables in Model 1 + glucose (Model 2).

RESULTS

The geometric mean [95% confidence interval (CI)] of hs-CRP was 0.36 mg/L (0.34-0.37). During the follow-up, 156 new T2DM cases were confirmed. In total sample, Model 2 HRs (95% CIs) for hs-CRP quartiles Q2-Q4 compared with Q1 were 0.69 (0.36-1.26), 1.47 (0.91-2.39) and 1.78 (1.10-2.88), respectively (p for linear trend = 0.014). Stratified analysis revealed that a statistically significant association was observed only in normal weight non-current smokers with Model 2 HRs (CIs) being 0.79 (0.29-2.17), 2.63 (1.25-5.56) and 3.19 (1.49-6.86) for Q2-Q4 compared with Q1, respectively (p for linear trend = 0.0006). The relationship did not change materially after further adjusting for log-homeostasis model assessment or exclusion of past smokers.

CONCLUSIONS

These findings imply that higher hs-CRP itself or existence of chronic systemic inflammation precedes onset of T2DM independent of obesity and smoking.

Statins modulate feedback regulation mechanisms between advanced glycation end-products and C-reactive protein: evidence in patients with acute myocardial infarction

OBJECTIVE

High sensitivity C-reactive protein (hsCRP) and advanced glycation end-products (AGEs) have been proposed as mediators in inflammation and atherosclerosis. Therefore, we studied the relation between AGE and hsCRP in patients with acute myocardial infarction (AMI).

METHODS

Patients with AMI diagnosis and satisfying our inclusion criteria were included during 2009-2011 in an unicentre registry of AMI patients for a cross-sectional study. The final cohort was composed of 156 patients (46.2% STEMI and 27.6% with type-2 diabetes). AGE and hsCRP were measured in plasma.

RESULTS

Diabetic patients were older than non-diabetics (68.6 ± 10.6 vs. 60.4 ± 13.9 years; p<0.05), presented more incidence of hypertension (62.8 vs. 36.3%; p<0.05) and were in a higher Killip class (p<0.05). The mean values of fluorescent AGE and hsCRP levels were 61.3 ± 49.8 AU and 2.4 ± 4.0 mg/L, respectively, and there were no differences in these parameters between diabetic and non-diabetic patients. A direct association between AGE and hsCRP levels was observed, mainly in diabetic patients (r=0.258; p=0.018). Importantly, this association disappeared in patients who had been treated with statins before their AMI (r=-0.055; p=0.845), but it was maintained in non-diabetic patients naïve for statins treatment (r=0.634; p<0.001), independently of other treatments and confounding parameters.

CONCLUSIONS

This is the first evidence in humans of a feedback regulation mechanism between CRP and the AGE-RAGE axis modulated by statins.

Glucagon-like peptide-1 protects against cardiac microvascular injury in diabetes via a cAMP/PKA/Rho-dependent mechanism

Impaired cardiac microvascular function contributes to cardiovascular complications in diabetes. Glucagon-like peptide-1 (GLP-1) exhibits potential cardioprotective properties in addition to its glucose-lowering effect. This study was designed to evaluate the impact of GLP-1 on cardiac microvascular injury in diabetes and the underlying mechanism involved. Experimental diabetes was induced using streptozotocin in rats. Cohorts of diabetic rats received a 12-week treatment of vildagliptin (dipeptidyl peptidase-4 inhibitor) or exenatide (GLP-1 analog). Experimental diabetes attenuated cardiac function, glucose uptake, and microvascular barrier function, which were significantly improved by vildagliptin or exenatide treatment. Cardiac microvascular endothelial cells (CMECs) were isolated and cultured in normal or high glucose medium with or without GLP-1. GLP-1 decreased high-glucose-induced reactive oxygen species production and apoptotic index, as well as the levels of NADPH oxidase such as p47(phox) and gp91(phox). Furthermore, cAMP/PKA (cAMP-dependent protein kinase activity) was increased and Rho-expression was decreased in high-glucose-induced CMECs after GLP-1 treatment. In conclusion, GLP-1 could protect the cardiac microvessels against oxidative stress, apoptosis, and the resultant microvascular barrier dysfunction in diabetes, which may contribute to the improvement of cardiac function and cardiac glucose metabolism in diabetes. The protective effects of GLP-1 are dependent on downstream inhibition of Rho through a cAMP/PKA-mediated pathway.

Reduced protein oxidation in Wistar rats supplemented with marine ω3 PUFAs

The potential effects of various dietary eicosapentaenoic acid (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6) ratios (1:1, 2:1, and 1:2, respectively) on protein redox states from plasma, kidney, skeletal muscle, and liver were investigated in Wistar rats. Dietary fish oil groups were compared with animals fed soybean and linseed oils, vegetable oils enriched in ω6 linoleic acid (LA; 18:2) and ω3 α-linolenic acid (ALA; 18:3), respectively. Fish oil treatments were effective at reducing the level of total fatty acids in plasma and enriching the plasmatic free fatty acid fraction and erythrocyte membranes in EPA and DHA. A proteomic approach consisting of fluorescein 5-thiosemicarbazide (FTSC) labeling of protein carbonyls, FTSC intensity visualization on 1-DE or 2-DE gels, and protein identification by MS/MS was used for the protein oxidation assessment. Albumin was found to be the most carbonylated protein in plasma for all dietary groups, and its oxidation level was significantly modulated by dietary interventions. Supplementation with an equal EPA:DHA ratio (1:1) showed the lowest oxidation score for plasma albumin, followed in increasing order of carbonylation by 1:2 <2:1 ≈ linseed < soybean. Oxidation patterns of myofibrillar skeletal muscle proteins and cytosolic proteins from kidney and liver also indicated a protective effect on proteins for the fish oil treatments, the 1:1 ratio exhibiting the lowest protein oxidation scores. The effect of fish oil treatments at reducing carbonylation on specific proteins from plasma (albumin), skeletal muscle (actin), and liver (albumin, argininosuccinate synthetase, 3-α-hydroxysteroid dehydrogenase) was remarkable. This investigation highlights the efficiency of dietary fish oil at reducing in vivo oxidative damage of proteins compared to oils enriched in the 18-carbon polyunsaturated fatty acids ω3 ALA and ω6 LA, and such antioxidant activity may differ among different fish oil sources because of variations in EPA/DHA content.

The pro-atherogenic effects of macrophages are reduced upon formation of a complex between C-reactive protein and lysophosphatidylcholine

Rationale

C-reactive protein (CRP) and lysophosphatidylcholine (LPC) are phosphorylcholine-(PC)-containing oxidized phospholipids (oxPLs) found in oxidized LDL (oxLDL), which trigger pro-atherogenic activities of macrophages during the process of atherosclerosis. It has been previously reported that CRP binds to the PC head group of oxLDL in a calcium-dependent manner. The aim of this study was to investigate the importance of binding between CRP and LPC to the pro-atherogenic activities of macrophages.

Objectives and findings

A chemiluminescent immunoassay and HPLC showed that human recombinant CRP formed a stable complex with LPC in the presence of calcium. The Kd value of the binding of the CRP-LPC complex to the receptors FcγRIA or FcγRIIA was 3–5 fold lower than that of CRP alone. The CRP-LPC complex triggered less potent generation of reactive oxygen species and less activation of the transcription factors AP-1 and NF-kB by human monocyte-derived macrophages in comparison to CRP or LPC alone. However, CRP did not affect activities driven by components of oxLDL lacking PC, such as upregulation of PPRE, ABCA1, CD36 and PPARγ and the enhancement of cholesterol efflux by human macrophages. The presence of CRP inhibited the association of Dil-labelled oxLDL to human macrophages.

Conclusions

The formation of complexes between CRP and PC-containing oxPLs, such as LPC, suppresses the pro-atherogenic effects of CRP and LPC on macrophages. This effect may in part retard the progression of atherosclerosis.