Investigating the Correlation between Serum Amyloid A and Infarct-Related Artery Patency Prior to Percutaneous Coronary Intervention in ST-Segment Elevation Myocardial Infarction Patients

Serum amyloid A (SAA) is a cardiovascular risk factor and may serve as a predictor of infarct-related artery (IRA) patency in patients with ST-segment elevation myocardial infarction (STEMI). We measured SAA levels in STEMI patients who underwent percutaneous coronary intervention (PCI) and investigated their association with IRA patency. According to the Thrombolysis in Myocardial Infarction (TIMI) flow grade, 363 STEMI patients undergoing PCI in our hospital were divided into an occlusion group (TIMI 0-2) and a patency group (TIMI 3). The SAA level before PCI was significantly higher in STEMI patients with IRA occluded than in those with patent ones. At a cutoff value of 36.9 mg/L, SAA had a sensitivity of 63.0% and a specificity of 90.6% (area under the ROC curve [AUC] = .833, 95% CI: .793-.873, P < .001). Multivariate logistic regression analysis showed that SAA was an independent predictor of IRA patency in STEMI patients before PCI (odds ratio [OR] = 1.041, 95% CI: 1.020-1.062, P < .001). SAA can be used as a potential predictor of IRA patency in STEMI patients before PCI.

Osteocytes/Osteoblasts Produce SAA3 to Regulate Hepatic Metabolism of Cholesterol

Hypercholesterolaemia is a systemic metabolic disease, but the role of organs other than liver in cholesterol metabolism is unappreciated. The phenotypic characterization of the Tsc1Dmp1 mice reveal that genetic depletion of tuberous sclerosis complex 1 (TSC1) in osteocytes/osteoblasts (Dmp1-Cre) triggers progressive increase in serum cholesterol level. The resulting cholesterol metabolic dysregulation is shown to be associated with upregulation and elevation of serum amyloid A3 (SAA3), a lipid metabolism related factor, in the bone and serum respectively. SAA3, elicited from the bone, bound to toll-like receptor 4 (TLR4) on hepatocytes to phosphorylate c-Jun, and caused impeded conversion of cholesterol to bile acids via suppression on cholesterol 7 α-hydroxylase (Cyp7a1) expression. Ablation of Saa3 in Tsc1Dmp1 mice prevented the CYP7A1 reduction in liver and cholesterol elevation in serum. These results expand the understanding of bone function and hepatic regulation of cholesterol metabolism and uncover a potential therapeutic use of pharmacological modulation of SAA3 in hypercholesterolaemia.

Blood-Based and Imaging Biomarkers of Atherosclerosis

Atherosclerosis is the main cause of arterial thrombosis, causing acute occlusive cardiovascular syndromes. Numerous risk prediction models have been developed, which mathematically combine multiple predictors, to estimate the risk of developing cardiovascular events. Current risk models typically do not include information from biomarkers that can potentially improve these existing prediction models especially if they are pathophysiologically relevant. Numerous cardiovascular disease biomarkers have been investigated that have focused on known pathophysiological pathways including those related to cardiac stress, inflammation, matrix remodelling, and endothelial dysfunction. Imaging biomarkers have also been studied that have yielded promising results with a potential higher degree of clinical applicability in detection of atherosclerosis and cardiovascular event prediction. To further improve therapy decision-making and guidance, there is continuing intense research on emerging biologically relevant biomarkers. As the pathogenesis of cardiovascular disease is multifactorial, improvements in discrimination and reclassification in risk prediction models will likely involve multiple biomarkers. This article will provide an overview of the literature on potential blood-based and imaging biomarkers of atherosclerosis studied so far, as well as potential future directions.

Very high HDL-C (high-density lipoprotein cholesterol) is associated with increased cardiovascular risk in patients with NSTEMI (non-ST-segment elevation myocardial infarction) undergoing PCI (percutaneous coronary intervention)

BACKGROUND

Studies in populations with or without cardiovascular disease have shown that very high HDL-C levels are associated with an increased risk of cardiovascular events. However, the exact relationship between HDL-C levels and long-term prognosis remains unknown in patients with myocardial infarction (MI) undergoing percutaneous coronary intervention (PCI).

METHODS

This was a post hoc secondary analysis of long-term follow-up results in patients undergoing PCI open-label, observational cohort study. Patients with MI who had undergone PCI were enrolled. Restricted cubic spline (RCS) analysis and logistic regression analysis were performed to assess the relationship between HDL-C levels and the risk of cardiovascular events.

RESULTS

A total of 1934 patients with MI undergoing PCI were enrolled in our analysis and our population was divided in 3 groups according to the HDL-C plasma levels: HDL-C < 40 mg/dL (low HDL-C); HDL-C between 40 and 80 mg/ dL (medium HDL-C); and HDL-C > 80 mg/dL (high HDL-C). RCS analysis showed a nonlinear U-shaped association between HDL-C levels and major adverse cardiac and cerebrovascular events (MACCE) in patients with NSTEMI with adjusted variables. After adjusting for potential confounders, the follow-up analysis indicated that high risk group had elevated occurrence of MACCE than low risk group (HDL-C 35 and 55 mg/dL) (OR:1.645, P = 0.006).

CONCLUSIONS

Our analysis demonstrated that there is a U-shaped association between HDL-C and MACCE in patients with NSTEMI undergoing PCI.

Indicators of Oxidative Stress in the Prediction of Coronary Artery Lesions in Patients With Kawasaki Disease

OBJECTIVES

The aim of this study was to examine the clinical significance of oxidative stress (OS)-related indices, including inflammatory markers and lipid and platelet (PLT) parameter, in coronary artery lesions (CALs) in Kawasaki disease (KD).

METHODS

Clinical data of 952 KD patients diagnosed between January 2019 and March 2022 were collected and divided into CAL and NCAL groups. All the KD patients were randomly divided into training set and verification set. The univariate analysis and multivariate logistic regression analysis of training set were used to identify the OS-related independent risk factors of CALs, which were then used to construct a predictive nomogram. Calibration curve and receiver operating characteristic curve were used to evaluate the performance of the model. The predictive nomogram was further validated on verification set.

RESULTS

In the training set, 137 KD patients (18.0%) showed CALs. C-reactive protein, serum amyloid A, PLT count, monocyte-to-high-density lipoprotein (HDL) ratio, and PLT-to-lymphocyte ratio were significantly higher, whereas HDL was lower in the CAL group than the NCAL group. Increased C-reactive protein, serum amyloid A, PLT, and decreased HDL were identified as independent risk factors. The nomogram constructed using these factors showed satisfactory calibration degree and discriminatory power (the area under the curve, 0.887). In the verification set, the area under the curve was 0.795.

CONCLUSION

The predictive nomogram constructed using 4 OS-related risk factors associated with CALs in patients with KD could be a useful tool for early diagnosis of CALs in KD.

Discovery of protein biomarkers for venous thromboembolism in non-small cell lung cancer patients through data-independent acquisition mass spectrometry

Objective

Non-small cell lung cancer (NSCLC) patients present a high incidence of venous thromboembolism (VTE) with poor prognosis. It is crucial to identify and diagnose VTE early. The study aimed to identify potential protein biomarkers and mechanism of VTE in NSCLC patients via proteomics research.

Methods

Proteomic analysis of the human plasma was performed through data-independent acquisition mass spectrometry for 20 NSCLC patients with VTE, and 15 NSCLC patients without VTE. Significantly differentially expressed proteins were analyzed by multiple bioinformatics method for further biomarker analysis.

Results

A total of 280 differentially expressed proteins were identified in VTE and non-VTE patients, where 42 were upregulated and 238 were downregulated. These proteins were involved in acute-phase response, cytokine production, neutrophil migration and other biological processes related to VTE and inflammation. Five proteins including SAA1, S100A8, LBP, HP and LDHB had significant change between VTE and non-VTE patients, with the area under the curve (AUC) were 0.8067, 0.8308, 0.7767, 0.8021, 0.8533, respectively.

Conclusions

SAA1, S100A8, LBP, HP and LDHB may serve as potential plasma biomarkers for diagnosis VTE in NSCLC patients.

The Role of Major Inflammatory Biomarkers in the Pathogenesis of Atrial Fibrillation

Many studies have reported a relationship between inflammation and atrial fibrillation (AF). According to the literature, inflammation is the key component in pathophysiological processes during the development of AF; the amplification of inflammatory pathways triggers AF, and, at the same time, AF increases the inflammatory state. The plasma levels of several inflammatory biomarkers are elevated in patients with AF; therefore, inflammation might contribute to both the maintenance and occurrence of AF and its thromboembolic complications. Numerous inflammatory markers have been linked to AF, including CD40 ligand, fibrinogen, matrix metalloproteinase (MMP)-9, monocyte chemoattractant protein-1, myeloperoxidase, plasminogen activator inhibitor-1, and serum amyloid A. There are many pathophysiological aspects of AF that are linked to these inflammatory biomarkers, including atrial structural remodeling and atrial dilatation, increased atrial myocyte expression, fluctuations in calcium cycling, cardiac remodeling promotion, increased cardiac myocyte proliferation and terminal differentiation, production of several MMPs, the pathogenesis of atherosclerosis and cardiomyocyte apoptosis, an increased degree of fibrosis in atrial myocardium, and the progression and development of atherogenesis and atherothrombosis. The present review article aims to provide an updated overview and focus on the basic role of different biomarkers of inflammation in the pathophysiological aspects of the pathogenesis of AF.

Association between Serum Amyloid A Level and White Matter Hyperintensity Burden: a Cross-Sectional Analysis in Patients with Acute Ischemic Stroke

INTRODUCTION

This work aimed to determine the potential link between white matter hyperintensity (WMH) burden and serum amyloid A (SAA) level in patients with acute ischemic stroke.

METHODS

Consecutive patients with acute large artery atherosclerosis (LAA) stroke between April 2021 and May 2022 were included. WMH volumes (periventricular, deep, and total) were measured using the Fazekas score and a semiautomated volumetric analysis on fluid-attenuated inversion recovery-magnetic resonance imaging. The burdens of WMH were scored to assess the dose-dependent association between SAA and WMH volume. Multivariate regression and a two-piecewise linear regression model were used to evaluate whether SAA levels are an independent predictor of WMH, and to discover the threshold effect or saturation effect of SAA levels with respect to WMH volume.

RESULTS

The mean age of patients was 63.2 ± 11.5 years, with 65.9% men. The median SAA level was 3.93 mg/L and the total WMH volume of 6.86 cm³. In the multivariable analysis, SAA remained an independent predictor of total WMH volume [β = 0.82, 95% confidence interval (CI) = 0.49-1.07, p < 0.001], periventricular WMH volume (adjusted β = 0.76, 95% CI = 0.46-1.07, p < 0.001), and deep WMH volume (adjusted β = 0.26, 95% CI = 0.06-0.45, p = 0.011) after controlling for confounders. Furthermore, SAA levels were associated with periventricular Fazekas score, deep Fazekas score, and Fazekas grades. Threshold effect and saturation effect analyses demonstrated a nonlinear relationship between SAA levels and periventricular white matter hyperintensity (PVWMH) volumes, with SAA levels (2.12-19.89 mg/L) having significant dose-dependent relationships with periventricular WMH volumes (adjusted β = 1.98, 95% CI = 1.12-2.84, p < 0.001).

CONCLUSION

SAA level ranging from 2.12 to 19.89 mg/L is dose-dependently associated with periventricular WMH development. These findings point the way forward for future research into the pathophysiology of WMH.

The Association of Acute Phase Proteins in Stress and Inflammation-Induced T2D

Acute phase proteins (APPs), such as plasminogen activator inhibitor-1 (PAI-1), serum amyloid A (SAA), and C-reactive protein (CRP), are elevated in type-2 diabetes (T2D) and are routinely used as biomarkers for this disease. These APPs are regulated by the peripheral mediators of stress (i.e., endogenous glucocorticoids (GCs)) and inflammation (i.e., pro-inflammatory cytokines), with both implicated in the development of insulin resistance, the main risk factor for the development of T2D. In this review we propose that APPs, PAI-1, SAA, and CRP, could be the causative rather than only a correlative link between the physiological elements of risk (stress and inflammation) and the development of insulin resistance.

Role of Serum Amyloid A in Abdominal Aortic Aneurysm and Related Cardiovascular Diseases

Epidemiological data positively correlate plasma serum amyloid A (SAA) levels with cardiovascular disease severity and mortality. Studies by several investigators have indicated a causal role for SAA in the development of atherosclerosis in animal models. Suppression of SAA attenuates the development of angiotensin II (AngII)-induced abdominal aortic aneurysm (AAA) formation in mice. Thus, SAA is not just a marker for cardiovascular disease (CVD) development, but it is a key player. However, to consider SAA as a therapeutic target for these diseases, the pathway leading to its involvement needs to be understood. This review provides a brief description of the pathobiological significance of this enigmatic molecule. The purpose of this review is to summarize the data relevant to its role in the development of CVD, the pitfalls in SAA research, and unanswered questions in the field.

Pro-Inflammatory Serum Amyloid a Stimulates Renal Dysfunction and Enhances Atherosclerosis in Apo E-Deficient Mice

Acute serum amyloid A (SAA) is an apolipoprotein that mediates pro-inflammatory and pro-atherogenic pathways. SAA-mediated signalling is diverse and includes canonical and acute immunoregulatory pathways in a range of cell types and organs. This study aimed to further elucidate the roles for SAA in the pathogenesis of vascular and renal dysfunction. Two groups of male ApoE-deficient mice were administered SAA (100 µL, 120 µg/mL) or vehicle control (100 µL PBS) and monitored for 4 or 16 weeks after SAA treatment; tissue was harvested for biochemical and histological analyses at each time point. Under these conditions, SAA administration induced crosstalk between NF-κB and Nrf2 transcriptional factors, leading to downstream induction of pro-inflammatory mediators and antioxidant response elements 4 weeks after SAA administration, respectively. SAA treatment stimulated an upregulation of renal IFN-γ with a concomitant increase in renal levels of p38 MAPK and matrix metalloproteinase (MMP) activities, which is linked to tissue fibrosis. In the kidney of SAA-treated mice, the immunolocalisation of inducible nitric oxide synthase (iNOS) was markedly increased, and this was localised to the parietal epithelial cells lining Bowman’s space within glomeruli, which led to progressive renal fibrosis. Assessment of aortic root lesion at the study endpoint revealed accelerated atherosclerosis formation; animals treated with SAA also showed evidence of a thinned fibrous cap as judged by diffuse collagen staining. Together, this suggests that SAA elicits early renal dysfunction through promoting the IFN-γ-iNOS-p38 MAPK axis that manifests as the fibrosis of renal tissue and enhanced cardiovascular disease.

Periodontitis induces endothelial dysfunction in mice

The treatment of periodontitis has numerous positive effects on established chronic health conditions, including cardiovascular disease and diabetes. However, ethical considerations do limit the establishment of human trials to investigate whether periodontitis promotes the early stages of chronic conditions. Therefore, the aim of this study was to investigate whether periodontitis induces endothelial dysfunction in hyperlipidemic apolipoprotein E gene-deficient (ApoE^-/-) mice. Forty-five 8-week-old ApoE^-/- mice were challenged by oral lavage with Porphyromonas gingivalis and Streptococcus gordonii for 4 weeks. A subgroup of animals (n = 15-17/group) was placed in a metabolic chamber immediately before euthanasia at 4 weeks to measure VO₂/CO₂ concentrations and voluntary locomotion. In infected and control animals alveolar bone levels were measured by x-ray imaging and endothelial function was determined by measuring endothelial-dependent vasorelaxation of aortic rings. The mRNA expression levels of serum amyloid A and tumor necrosis factor were determined in liver tissues by qRT PCR and protein concentrations in serum by ELISA. Caecal contents were analysed by sequencing to determine changes to the gut microbiota to investigate linkages between microbiome and systemic changes. The results showed that oral lavage of P. gingivalis and S. gordonii for 4 weeks, initiated periodontitis in ApoE^-/- mice, similar to the human situation. The oral inflammation was accompanied by a significant increase in mRNA expression of pro-inflammatory mediators serum amyloid A1 and tumor necrosis factor in the liver. Mice with periodontitis also exhibited impaired endothelial-dependent vasorelaxation responses to acetylcholine. This systemic response was connected to increased energy expenditure, locomotion and respiratory quotient. No differences were detected in caecal microbiota between the infected and control animals. Overall, this is the first report that provide evidence that periodontitis induces endothelial dysfunction in mice. Other systemic responses observed in response to the local reaction need further investigation. The study suggests that early prevention of periodontitis may help limit the early stages of endothelial dysfunction that is linked to atherogenesis in humans.

Lipoproteins and lipids in cardiovascular disease: from mechanistic insights to therapeutic targeting

With cardiovascular disease being the leading cause of morbidity and mortality worldwide, effective and cost-efficient therapies to reduce cardiovascular risk are highly needed. Lipids and lipoprotein particles crucially contribute to atherosclerosis as underlying pathology of cardiovascular disease and influence inflammatory processes as well as function of leukocytes, vascular and cardiac cells, thereby impacting on vessels and heart. Statins form the first-line therapy with the aim to block cholesterol synthesis, but additional lipid-lowering drugs are sometimes needed to achieve low-density lipoprotein (LDL) cholesterol target values. Furthermore, beyond LDL cholesterol, also other lipid mediators contribute to cardiovascular risk. This review comprehensively discusses low- and high-density lipoprotein cholesterol, lipoprotein (a), triglycerides as well as fatty acids and derivatives in the context of cardiovascular disease, providing mechanistic insights into their role in pathological processes impacting on cardiovascular disease. Also, an overview of applied as well as emerging therapeutic strategies to reduce lipid-induced cardiovascular burden is provided.

High-Density Lipoprotein (HDL) Inhibits Serum Amyloid A (SAA)-Induced Vascular and Renal Dysfunctions in Apolipoprotein E-Deficient Mice

Serum amyloid A (SAA) promotes endothelial inflammation and dysfunction that is associated with cardiovascular disease and renal pathologies. SAA is an apoprotein for high-density lipoprotein (HDL) and its sequestration to HDL diminishes SAA bioactivity. Herein we investigated the effect of co-supplementing HDL on SAA-mediated changes to vascular and renal function in apolipoprotein E-deficient (ApoE^-/^-) mice in the absence of a high-fat diet. Male ApoE^-/- mice received recombinant human SAA or vehicle (control) by intraperitoneal (i.p.) injection every three days for two weeks with or without freshly isolated human HDL supplemented by intravenous (i.v.) injection in the two weeks preceding SAA stimulation. Aorta and kidney were harvested 4 or 18 weeks after commencement of treatment. At 4 weeks after commencement of treatment, SAA increased aortic vascular cell adhesion molecule (VCAM)-1 expression and F₂-isoprostane level and decreased cyclic guanosine monophosphate (cGMP), consistent with SAA stimulating endothelial dysfunction and promoting atherosclerosis. SAA also stimulated renal injury and inflammation that manifested as increased urinary protein, kidney injury molecule (KIM)-1, and renal tissue cytokine/chemokine levels as well as increased protein tyrosine chlorination and P38 MAPkinase activation and decreased in Bowman's space, confirming that SAA elicited a pro-inflammatory phenotype in the kidney. At 18 weeks, vascular lesions increased significantly in the cohort of ApoE^-/- mice treated with SAA alone. By contrast, pretreatment of mice with HDL decreased SAA pro-inflammatory activity, inhibited SAA enhancement of aortic lesion size and renal function, and prevented changes to glomerular Bowman's space. Taken together, these data indicate that supplemented HDL reduces SAA-mediated endothelial and renal dysfunction in an atherosclerosis-prone mouse model.

CTRP3 Alleviates Ox-LDL-Induced Inflammatory Response and Endothelial Dysfunction in Mouse Aortic Endothelial Cells by Activating the PI3K/Akt/eNOS Pathway

C1q/tumor necrosis factor-related protein-3 (CTRP3) is a novel, certified, adipokine that beneficially regulates metabolism and inflammation in the cardiovascular system. Atherosclerotic plaque rupturing and secondary thrombosis cause vascular disorders, such as myocardial infarction and unstable angina. However, the underlying role of CTRP3 in atherosclerosis remains unclear. In this study, we aimed to elucidate whether and how CTRP3 ameliorates inflammation and endothelial dysfunction caused by oxidized low-density lipoprotein (ox-LDL). We first confirmed that CTRP3 expression was inhibited in ApoE-/- mice, compared to normal mice. Then, pcDNA-CTRP3 and siCTRP3 were transfected into mouse aortic endothelial cells after ox-LDL stimulation, and we observed that enhanced CTRP3 remarkably downregulated CRP, TNF-α, IL-6, CD40, and CD40L. We also observed that overexpression of CTRP3 elevated cell activity and decreased lactated hydrogenase release, accompanied by a marked reduction in cell apoptosis induced by ox-LDL. Meanwhile, overexpressed CTRP3 caused a decrease in Ang II, ICAM-1, and VCAM-1 expression, and it restored the balance between ET-1 and NO. Mechanism analysis confirmed that incremental CTRP3 upregulated p-PI3K, p-Akt, and p-eNOS expression, indicating that CTRP3 facilitated activation of the PI3K/Akt/eNOS pathway. On the contrary, siCTRP3 exerted the opposite effect to this activation. Blocking these pathways using LY294002 or L-NAME attenuated the protective role of CTRP3. Overall, these results suggest that CTRP3 can efficiently inhibit the inflammatory response and endothelial dysfunction induced by ox-LDL in mouse aortic endothelial cells, perhaps by activating the PI3K/Akt/eNOS pathway, indicating a promising strategy against atherosclerosis.

The cardiovascular phenotype of adult patients with phenylketonuria

BACKGROUND

Patients with Phenylketonuria (PKU) are exposed to multiple cardiovascular risk factors, but the clinical significance of these abnormalities is yet unknown. The purpose of this study was to characterize the cardiovascular phenotype in adult patients with PKU by clinical and dietary data, measurements of biochemical markers, and non-invasive examination of vascular functions.

RESULTS

Twenty-three adult patients with PKU (age: 18-47 y; 30.8 ± 8.4 y) and 28 healthy controls (age: 18-47 y; 30.1 ± 9.1 y) were included in this study. PKU patients had significantly higher systolic and diastolic blood pressure, increased resting heart rate and a higher body mass index. Total cholesterol and non-HDL cholesterol levels were significantly increased in PKU patients, whereas plasma levels of HDL cholesterol and its subfraction HDL2 (but not HDL3) were significantly decreased. The inflammatory markers C-reactive protein and serum amyloid A protein and the serum oxidative stress marker malondialdehyde were significantly higher in patients with PKU. Venous occlusion plethysmography showed marked reduction in post-ischemic blood flow and the carotid to femoral pulse wave velocity was significantly increased demonstrating endothelial dysfunction and increased vascular stiffness.

CONCLUSIONS

This study shows that the cardiovascular phenotype of adult PKU patients is characterized by an accumulation of traditional cardiovascular risk factors, high levels of inflammatory and oxidative stress markers, endothelial dysfunction and vascular stiffness. These data indicate the need for early cardiovascular risk reduction in patients with PKU.

Role of serum amyloid A in atherosclerosis

PURPOSE OF REVIEW

Acute phase serum amyloid A (SAA) is persistently elevated in chronic inflammatory conditions, and elevated levels predict cardiovascular risk in humans. More recently, murine studies have demonstrated that over-expression of SAA increases and deficiency/suppression of SAA attenuates atherosclerosis. Thus, beyond being a biomarker, SAA appears to play a causal role in atherogenesis. The purpose of this review is to summarize the data supporting SAA as a key player in atherosclerosis development.

RECENT FINDINGS

A number of pro-inflammatory and pro-atherogenic activities have been ascribed to SAA. However, the literature is conflicted, as recombinant SAA, and/or lipid-free SAA, used in many of the earlier studies, do not reflect the activity of native human or murine SAA, which exists largely lipid-associated. Recent literatures demonstrate that SAA activates the NLRP3 inflammasome, alters vascular function, affects HDL function, and increases thrombosis. Importantly, SAA activity appears to be regulated by its lipid association, and HDL may serve to sequester and limit SAA activity.

SUMMARY

SAA has many pro-inflammatory and pro-atherogenic activities, is clearly demonstrated to affect atherosclerosis development, and may be a candidate target for clinical trials in cardiovascular diseases.

SAA1 increases NOX4/ROS production to promote LPS-induced inflammation in vascular smooth muscle cells through activating p38MAPK/NF-κB pathway

Background

To investigate the effects of serum amyloid A1 (SAA1) on lipopolysaccharide (LPS) -induced inflammation in vascular smooth muscle cells (VSMCs). SAA1 expression was detected in LPS induced VSMCs at different concentrations for different time by using Western blotting. After pre-incubation with recombinant SAA1 protein, VSMCs were treated with 1 μg/ml LPS for 24 h. The VSMCs were then divided into Control, SAA1 siRNA, Nox4 siRNA, LPS, LPS + SAA1 siRNA, LPS + Nox4 siRNA and LPS + SAA1 siRNA + Nox4 groups. MTT was performed to observe the toxicity of VSMCs. Lucigenin-enhanced chemiluminescence method was used to detect superoxide anion (O₂⁻) production and NADPH oxidase activity. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to determine expressions of inflammatory factors. Western blotting was used to determine expressions of NOX-4 and p38MAPK/NF-κB pathway related proteins.

Results

LPS promoted SAA1 protein expression in a concentration−/time-dependent manner. Recombinant SAA1 protein could increase NOX4/ROS production and promote the release of inflammatory factors (IL-1β, IL-6, IL-8, IL-17, TNF-α and MCP-1) in LPS (1 μg/ml) - induced VSMCs. Besides, both SAA1 siRNA and NOX-4 siRNA could not only enhance the O₂⁻ production and NADPH oxidase activity, but also up-regulate the protein expression of NOX4, the release of inflammatory factors, and the levels of p-p38 and p-NF-κB p65 in LPS-induced VSMCs. However, no significant differences in each index were observed between LPS group and LPS + SAA1 siRNA + Nox4 group.

Conclusion

SAA1-mediated NOX4/ROS pathway could activate p38MAPK/NF-κB pathway, thereby contributing to the release of inflammatory factors in LPS-induced VSMCs.

Inflammatory cytokines in type 2 diabetes mellitus as facilitators of hypercoagulation and abnormal clot formation

BACKGROUND

The global burden of type 2 diabetes mellitus (T2DM), together with the presence of cardiovascular risk in this population, is reaching pandemic levels. A prominent feature of T2DM is chronic and systemic inflammation, with the accompanying presence of circulating and dysregulated inflammatory biomarkers; which in turn is associated with abnormal clot formation.

METHODS

Here, we investigate the correlation between abnormal blood clotting, using thromboelastography (TEG), clot ultrastructure using scanning electron microscopy (SEM) and the presence of a dysregulated inflammatory cytokine profile, by examining various circulating biomarkers.

RESULTS

Our results show that many biomarkers, across TEG, cytokine and lipid groups, were greatly dysregulated in the T2DM sample. Furthermore, our T2DM sample's coagulation profiles were significantly more hypercoagulable when compared to our heathy sample, and ultrastructural analysis confirmed a matted and denser clot structure in the T2DM sample.

CONCLUSIONS

We suggest that dysregulated circulating molecules may in part be responsible for a hypercoagulable state and vascular dysfunction in the T2DM sample. We propose further that a personalized approach could be of great value when planning treatment and tracking the patient health status after embarking on a treatment regimes, and that looking to novel inflammatory and vascular biomarkers might be crucial.

Olive Leaf Extract Attenuates Inflammatory Activation and DNA Damage in Human Arterial Endothelial Cells

Olive leaf extract (OLE) is used in traditional medicine as a food supplement and as an over-the-counter drug for a variety of its effects, including anti-inflammatory and anti-atherosclerotic ones. Mechanisms through which OLE could modulate these pathways in human vasculature remain largely unknown. Serum amyloid A (SAA) plays a causal role in atherosclerosis and cardiovascular diseases and induces pro-inflammatory and pro-adhesive responses in human coronary artery endothelial cells (HCAEC). Within this study we explored whether OLE can attenuate SAA-driven responses in HCAEC. HCAEC were treated with SAA (1,000 nM) and/or OLE (0.5 and 1 mg/ml). The expression of adhesion molecules VCAM-1 and E-selectin, matrix metalloproteinases (MMP2 and MMP9) and microRNA 146a, let-7e, and let-7g (involved in the regulation of inflammation) was determined by qPCR. The amount of secreted IL-6, IL-8, MIF, and GRO-α in cell culture supernatants was quantified by ELISA. Phosphorylation of NF-κB was assessed by Western blot and DNA damage was measured using the COMET assay. OLE decreased significantly released protein levels of IL-6 and IL-8, as well as mRNA expression of E-selectin in SAA-stimulated HCAEC and reduced MMP2 levels in unstimulated cells. Phosphorylation of NF-κB (p65) was upregulated in the presence of SAA, with OLE significantly attenuating this SAA-induced effect. OLE stabilized SAA-induced upregulation of microRNA-146a and let-7e in HCAEC, suggesting that OLE could fine-tune the SAA-driven activity of NF-κB by changing the microRNA networks in HCAEC. SAA induced DNA damage and worsened the oxidative DNA damage in HCAEC, whereas OLE protected HCAEC from SAA- and H₂O₂-driven DNA damage. OLE significantly attenuated certain pro-inflammatory and pro-adhesive responses and decreased DNA damage in HCAEC upon stimulation with SAA. The reversal of SAA-driven endothelial activation by OLE might contribute to its anti-inflammatory and anti-atherogenic effects in HCAEC.

Serum Amyloid A Stimulates Vascular and Renal Dysfunction in Apolipoprotein E-Deficient Mice Fed a Normal Chow Diet

Elevated serum amyloid A (SAA) levels may promote endothelial dysfunction, which is linked to cardiovascular and renal pathologies. We investigated the effect of SAA on vascular and renal function in apolipoprotein E-deficient (ApoE^−/−) mice. Male ApoE^−/− mice received vehicle (control), low-level lipopolysaccharide (LPS), or recombinant human SAA by i.p. injection every third day for 2 weeks. Heart, aorta and kidney were harvested between 3 days and 18 weeks after treatment. SAA administration increased vascular cell adhesion molecule (VCAM)-1 expression and circulating monocyte chemotactic protein (MCP)-1 and decreased aortic cyclic guanosine monophosphate (cGMP), consistent with SAA inhibiting nitric oxide bioactivity. In addition, binding of labeled leukocytes to excised aorta increased as monitored using an ex vivo leukocyte adhesion assay. Renal injury was evident 4 weeks after commencement of SAA treatment, manifesting as increased plasma urea, urinary protein, oxidized lipids, urinary kidney injury molecule (KIM)-1 and multiple cytokines and chemokines in kidney tissue, relative to controls. Phosphorylation of nuclear-factor-kappa-beta (NFκB-p-P65), tissue factor (TF), and macrophage recruitment increased in kidneys from ApoE^−/− mice 4 weeks after SAA treatment, confirming that SAA elicited a pro-inflammatory and pro-thrombotic phenotype. These data indicate that SAA impairs endothelial and renal function in ApoE^−/− mice in the absence of a high-fat diet.

NFκB Inhibition Mitigates Serum Amyloid A-Induced Pro-Atherogenic Responses in Endothelial Cells and Leukocyte Adhesion and Adverse Changes to Endothelium Function in Isolated Aorta

The acute phase protein serum amyloid A (SAA) is associated with endothelial dysfunction and early-stage atherogenesis. Stimulation of vascular cells with SAA increases gene expression of pro-inflammation cytokines and tissue factor (TF). Activation of the transcription factor, nuclear factor kappa-B (NFκB), may be central to SAA-mediated endothelial cell inflammation, dysfunction and pro-thrombotic responses, while targeting NFκB with a pharmacologic inhibitor, BAY11-7082, may mitigate SAA activity. Human carotid artery endothelial cells (HCtAEC) were pre-incubated (1.5 h) with 10 μM BAY11-7082 or vehicle (control) followed by SAA (10 μg/mL; 4.5 h). Under these conditions gene expression for TF and Tumor Necrosis Factor (TNF) increased in SAA-treated HCtAEC and pre-treatment with BAY11-7082 significantly (TNF) and marginally (TF) reduced mRNA expression. Intracellular TNF and interleukin 6 (IL-6) protein also increased in HCtAEC supplemented with SAA and this expression was inhibited by BAY11-7082. Supplemented BAY11-7082 also significantly decreased SAA-mediated leukocyte adhesion to apolipoprotein E-deficient mouse aorta in exvivo vascular flow studies. In vascular function studies, isolated aortic rings pre-treated with BAY11-7082 prior to incubation with SAA showed improved endothelium-dependent vasorelaxation and increased vascular cyclic guanosine monophosphate (cGMP) content. Together these data suggest that inhibition of NFκB activation may protect endothelial function by inhibiting the pro-inflammatory and pro-thrombotic activities of SAA.

Markers of Atherosclerosis: Part 1 - Serological Markers

Atherosclerosis is a major contributor to morbidity and mortality worldwide. With therapeutic consequences in mind, several risk scores are being used to differentiate individuals with low, intermediate or high cardiovascular (CV) event risk. The most appropriate management of intermediate risk individuals is still not known, therefore, novel biomarkers are being sought to help re-stratify them as low or high risk. This narrative review is presented in two parts. Here, in Part 1, we summarise current knowledge on serum (serological) biomarkers of atherosclerosis. Among novel biomarkers, high sensitivity C-reactive protein (hsCRP) has emerged as the most promising in chronic situations, others need further clinical studies. However, it seems that a combination of serum biomarkers offers more to risk stratification than either biomarker alone. In Part 2, we address genetic and imaging markers of atherosclerosis, as well as other developments relevant to risk prediction.

No effects without causes: the Iron Dysregulation and Dormant Microbes hypothesis for chronic, inflammatory diseases

Since the successful conquest of many acute, communicable (infectious) diseases through the use of vaccines and antibiotics, the currently most prevalent diseases are chronic and progressive in nature, and are all accompanied by inflammation. These diseases include neurodegenerative (e.g. Alzheimer's, Parkinson's), vascular (e.g. atherosclerosis, pre-eclampsia, type 2 diabetes) and autoimmune (e.g. rheumatoid arthritis and multiple sclerosis) diseases that may appear to have little in common. In fact they all share significant features, in particular chronic inflammation and its attendant inflammatory cytokines. Such effects do not happen without underlying and initially 'external' causes, and it is of interest to seek these causes. Taking a systems approach, we argue that these causes include (i) stress-induced iron dysregulation, and (ii) its ability to awaken dormant, non-replicating microbes with which the host has become infected. Other external causes may be dietary. Such microbes are capable of shedding small, but functionally significant amounts of highly inflammagenic molecules such as lipopolysaccharide and lipoteichoic acid. Sequelae include significant coagulopathies, not least the recently discovered amyloidogenic clotting of blood, leading to cell death and the release of further inflammagens. The extensive evidence discussed here implies, as was found with ulcers, that almost all chronic, infectious diseases do in fact harbour a microbial component. What differs is simply the microbes and the anatomical location from and at which they exert damage. This analysis offers novel avenues for diagnosis and treatment.

Editorial: dose-dependent ZnO particle-induced acute phase response in humans warrants re-evaluation of occupational exposure limits for metal oxides

Epidemiological studies link inhalation of particles to increased risk of cardiovascular disease. Inhaled particles may induce cardiovascular disease by several different mechanisms including translocation of particles to systemic circulation, activation of airway sensory nerves resulting in autonomic imbalance and particle-induced pulmonary inflammation and acute phase response.The acute phase response is the systemic response to acute and chronic inflammatory states caused by for example bacterial infection, virus infection, trauma and infarction. It is characterized by differential expression of ca. 50 different acute phase proteins including C-reactive protein and Serum amyloid A, which are the most differentially up-regulated acute phase response proteins. Blood levels of these two acute phase proteins are closely associated with risk of cardiovascular disease in epidemiological studies and SAA has been causally related to the formation of plaques in the aorta in animal studies.In a recent paper in Particle and Fibre Toxicology, Christian Monsé et al. provide evidence that inhalation of ZnO nanoparticles induces dose-dependent acute phase response in humans at dose levels well below the current mass-based occupational exposure limits in a number of countries including Germany, The Netherlands, UK, Sweden, Denmark and the US.Given the evidence suggesting a causal relationship between increased levels of serum amyloid A and atherosclerosis, the current results call for a re-evaluation of occupational exposure limits for a number of particle exposures including ZnO taking induction of acute phase response into account. Furthermore, it underscores cardiovascular disease as an occupational disease.

Serum amyloid A, procalcitonin, highly sensitive C reactive protein and tumor necrosis factor alpha levels and acute inflammatory response in patients with hemolysis, elevated liver enzymes, low platelet count (HELLP) and eclampsia

AIM

The aim of this study was to determine the relationship between serum amyloid A (SAA), procalcitonin (ProC), highly sensitive C reactive protein (hsCRP) and tumor necrosis factor (TNF) alpha activity in patients with pre-eclampsia, eclampsia and hemolysis, elevated liver enzymes, low platelet count (HELLP), and the pathogenesis and severity of the disease.

METHOD

Ninety patients at ≥ 32 gestational weeks, according to the last date of menstruation and ultra-sonographic measurements, diagnosed with pre-eclampsia (30 patients), eclampsia (30 patients) or HELLP syndrome (30 patients) were included in the study. Thirty healthy pregnant women from the outpatient clinic during the same period were recruited as the control. The age, gravida, parity, gestational age, systolic and diastolic blood pressures, proteinuria, hemoglobin, thrombocyte count, liver function tests (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, SAA, TNF alpha, ProC and hsCRP levels during pregnancy) were determined and recorded.

RESULTS

No statistically significant differences were detected between the four groups in terms of age, gravida, parity, gestational age and hemoglobin parameters (P > 0.05). When compared to the control, systolic and diastolic blood pressures, spot and 24 h urine protein levels, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, SAA, ProC, hsCRP and TNF alpha levels were significantly high and thrombocyte levels were low in the pre-eclamptic, eclamptic and HELLP groups (P < 0.05).

CONCLUSION

The investigated parameters were useful to gain an understanding of the maternal inflammatory profile of pre-eclampsia and might be beneficial as markers to predict complications such as HELLP and eclampsia and to provide the necessary preventive approach in these patients.

Manifestations of Renal Impairment in Fructose-induced Metabolic Syndrome

Introduction International studies show an increased incidence of chronic kidney disease (CKD) in patients with metabolic syndrome (MS). It is assumed that the major components of MS - obesity, insulin resistance, dyslipidemia, and hypertension - are linked to renal damage through the systemic release of several pro-inflammatory mediators, such as uric acid (UA), C-reactive protein (CRP), and generalized oxidative stress. The aim of the present study was to investigate the extent of kidney impairment and manifestations of dysfunction in rats with fructose-induced MS. Methods We used a model of high-fructose diet in male Wistar rats with 35% glucose-fructose corn syrup in drinking water over a duration of 16 weeks. The experimental animals were divided into two groups: control and high-fructose drinking (HFD). Serum samples were obtained from both groups for laboratory study, and the kidneys were extracted for observation via light microscopy examination. Results All HFD rats developed obesity, hyperglycemia, hypertriglyceridemia, increased levels of CRP and UA (when compared to the control group), and oxidative stress with high levels of malondialdehyde and low levels of reduced glutathione. The kidneys of the HFD group revealed a significant increase in kidney weight in the absence of evidence of renal dysfunction and electrolyte disturbances. Under light microscopy, the kidneys of the HFD group revealed amyloid deposits in Kimmelstiel-Wilson-like nodules and the walls of the large caliber blood vessels, early-stage atherosclerosis with visible ruptures and scarring, hydropic change (vacuolar degeneration) in the epithelial cells covering the proximal tubules, and increased eosinophilia in the distant tubules when compared to the control group. Conclusion Under the conditions of a fructose-induced metabolic syndrome, high serum UA and CRP correlate to the development of early renal disorders without a clinical manifestation of renal dysfunction. These phenomena are of particular importance for assessing the risk of developing future CKD.

The effect of tocopheryl phosphates (TPM) on the development of atherosclerosis in apolipoprotein-E deficient mice

α-Tocopheryl phosphate (TP) is a naturally occurring form of vitamin E found in the body. In the present study we compared the ability of an α-TP mixture (TPM) against a standard vitamin E supplement, α-tocopherol acetate (TA) on the development of atherosclerotic lesions in ApoE-deficient mice. Mice were maintained on either a normal chow diet for 24 weeks (Normal Diet), vs a group in which the final 8 weeks of the 24-week period mice were placed on a high fat (21%), high cholesterol (0.15%) challenge diet (HFHC), to exacerbate atherosclerotic lesion development.. The difference in these two control groups established the extent of the diet-induced atherosclerotic lesion development. Mice in the various treatment groups received either TA (300 mg/kg chow) or TPM (6.7-200 mg/kg chow) for 24 weeks, with TPM treatment resulting in dose-dependent significant reductions in atherosclerotic lesion formation and plasma levels of pro-inflammatory cytokines. TA-treated mice, with the tocopherol equivalent TPM dose (200 mg/kg chow), showed no significant reduction in plasma lipid levels or evidence for aortic lesion regression. At this TPM equivalent TA dose, a 44% reduction in aortic lesion formation was observed. In addition, these TPM treated mice, also showed a marked reduction in aortic superoxide formation and decreased circulating plasma levels of known pro-inflammatory markers IL-6, MCP-1, IL-1β, IFN-γ and TNF-α. These findings indicate that TPM treatment slows progression of atherosclerotic lesions in ApoE-deficient mice with this effect potentially involving reduced oxidative stress and decreased inflammation.

Effect of tofacitinib on lipid levels and lipid-related parameters in patients with moderate to severe psoriasis

BACKGROUND

Psoriasis is a systemic inflammatory disease associated with increased cardiovascular (CV) risk and altered lipid metabolism. Tofacitinib is an oral Janus kinase inhibitor.

OBJECTIVE

The aim of the study was to investigate the effects of tofacitinib on traditional and nontraditional lipid parameters and CV risk markers in patients with psoriasis from a phase III study, OPT Pivotal 1.

METHODS

Patients with psoriasis were randomized to tofacitinib 5 or 10 mg twice daily (BID) or placebo BID. Serum samples were collected at baseline, week 4, and week 16. Analyses included serum cholesterol levels, triglycerides, lipoproteins, lipid particles, lipid-related parameters/CV risk markers, and high-density lipoprotein (HDL) function analyses.

RESULTS

At week 16, small concurrent increases in mean low-density lipoprotein cholesterol (LDL-C) and HDL cholesterol (HDL-C) levels were observed with tofacitinib; total cholesterol/HDL-C ratio did not change. There was no significant change in the number of small dense LDL particles, which are considered to be more atherogenic than large particles, and oxidized LDL did not increase. Paraoxonase 1 activity, linked to HDL antioxidant capacity, increased, and HDL-associated serum amyloid A, which reduces the anti-atherogenic potential of HDL, decreased. HDL capacity to promote cholesterol efflux from macrophages did not change. Lecithin-cholesterol acyltransferase activity, which is associated with reverse cholesterol transport, increased. Markers of systemic inflammation, serum amyloid A and C-reactive protein, decreased with tofacitinib.

CONCLUSION

While small increases in lipid levels are observed with tofacitinib treatment in patients with psoriasis, effects on selected lipid-related parameters and other circulating CV risk biomarkers are not suggestive of an increased CV risk [NCT01276639].

S100A8/A9 and S100A9 reduce acute lung injury

S100A8 and S100A9 are myeloid cell-derived proteins that are elevated in several types of inflammatory lung disorders. Pro- and anti-inflammatory properties are reported and these proteins are proposed to activate TLR4. S100A8 and S100A9 can function separately, likely through distinct receptors but a systematic comparison of their effects in vivo are limited. Here we assess inflammation in murine lung following S100A9 and S100A8/A9 inhalation. Unlike S100A8, S100A9 promoted mild neutrophil and lymphocyte influx, possibly mediated in part, by increased mast cell degranulation and selective upregulation of some chemokine genes, particularly CXCL-10. S100 proteins did not significantly induce proinflammatory mediators including TNF-α, interleukin-1β (IL-1β), IL-6 or serum amyloid A3 (SAA3). In contrast to S100A8, neither preparation induced S100A8 or IL-10 mRNA/protein in airway epithelial cells, or in tracheal epithelial cells in vitro. Like S100A8, S100A9 and S100A8/A9 reduced neutrophil influx in acute lung injury provoked by lipopolysaccharide (LPS) challenge but were somewhat less inhibitory, possibly because of differential effects on expression of some chemokines, IL-1β, SAA3 and IL-10. Novel common pathways including increased induction of an NAD⁺-dependent protein deacetylase sirtuin-1 that may reduce NF-κB signalling, and increased STAT3 activation may reduce LPS activation. Results suggest a role for these proteins in normal homeostasis and protective mechanisms in the lung.

iTRAQ-based quantitative proteomics reveals important host factors involved in the high pathogenicity of the H5N1 avian influenza virus in mice

We previously reported a pair of H5N1 avian influenza viruses which are genetically similar but differ greatly in their virulence in mice. A/Chicken/Jiangsu/k0402/2010 (CK10) is highly lethal to mice, whereas A/Goose/Jiangsu/k0403/2010 (GS10) is avirulent. In this study, to investigate the host factors that account for their virulence discrepancy, we compared the pathology and host proteome of the CK10- or GS10-infected mouse lung. Moderate lung injury was observed from CK10-infected animals as early as the first day of infection, and the pathology steadily progressed at later time point. However, only mild lesions were observed in GS10-infected mouse lung at the late infection stage. Using the quantitative iTRAQ coupled LC-MS/MS method, we first found that more significantly differentially expressed (DE) proteins were stimulated by GS10 compared with CK10. However, bio-function analysis of the DE proteins suggested that CK10 induced much stronger inflammatory response-related functions than GS10. Canonical pathway analysis also demonstrated that CK10 highly activated the "Acute Phase Response Signaling," which results in a wide range of biological activities in response to viral infection, including many inflammatory processes. Further in-depth analysis showed that CK10 exacerbated acute lung injury-associated responses, including inflammatory response, cell death, reactive oxygen species production and complement response. In addition, some of these identified proteins that associated with the lung injury were further confirmed to be regulated in vitro. Therefore, our findings suggest that the early increased lung injury-associated host response induced by CK10 may contribute to the lung pathology and the high virulence of this virus in mice.

Double Filtration Plasma Apheresis Shortens Hospital Admission Duration of Patients With Severe Hypertriglyceridemia-Associated Acute Pancreatitis

OBJECTIVES

The treatment effectiveness of double filtration plasma apheresis (DFPP) on severe hypertriglyceridemia-associated acute pancreatitis (STAP) has been questioned because the currently defined serum triglyceride level--1000 mg/dL--is too low for STAP. Given this, we aimed to investigate DFPP effectiveness when we elevated STAP definition to 5000 mg/dL serum triglyceride.

METHODS

We performed nested case-control studies for STAP patients and divided them into groups "with" or "without" DFPP. We further recruited outpatient asymptomatic hypertriglyceridemia patients with STAP history, then divided them into groups "with" or "without" prophylactic DFPP once every 3 to 6 months for 2 years. We observed hospitalization duration and STAP recurrence between patients with and patients without DFPP.

RESULTS

Twelve STAP patients receiving DFPP had a median hospitalization of 5 days, whereas 24 patients without DFPP had 10 days (P = 0.009). Six outpatient referrals with STAP history receiving prophylactic DFPP showed no STAP recurrences whereas 6 without DFPP showed 3 recurrences (P = 0.046). For the 25 patients whose serum triglyceride exceeded 5000 mg/dL, 11 receiving DFPP had median hospitalization of 5 days while 14 without DFPP had 11 days (P = 0.012).

CONCLUSIONS

When applied to serum triglyceride in excess of 5000 mg/dL, DFPP removes oxidized and inflammatory lipoproteins, shortens hospitalization duration, and minimizes STAP recurrence.

Oxidatively altered IgG with increased immunoreactivity to β2-glycoprotein I and its peptide clusters influence human coronary artery endothelial cells

Oxidative stress has been shown to play a role in modifying antibodies in favor of higher auto-immunoreactivity. We studied the immunoreactivity of oxidized IgG (oxIgG) to β2-glycoprotein I (β2GPI), six peptide sequences corresponding to amino acid clusters on its different domains, to determine their effects on human coronary artery endothelial cells (HCAEC). Human IgG was purified from seven donors, electro-oxidized and checked for immunoreactivity and avidity to β2GPI and to peptides by ELISA. Conformational stability and antibody-antigen complex formation of oxIgG was analyzed by fluorescence spectroscopy and dynamic light scattering. Resting and activated sub-confluent HCAEC were stimulated with oxIgG or IgG. Secreted cytokines were measured by ELISA. Immunoreactivity of seven oxIgG samples increased to 7.5-fold against β2GPI and to 3.8-fold against six peptides as compared to IgG. oxIgG showed low avidity "properties." Conformational changes and exposure of protein hydrophobic regions were confirmed by an elevation in fluorescence (2.4- to 5.0-fold) on bis-ANS dye binding to oxIgG. oxIgG significantly elevated the release of GROα and IL-8 in resting and activated states of HCAEC. Oxidation alters IgG in favor of autoreactivity toward whole β2GPI and corresponding peptides on different domains of β2GPI and could lead to dysfunction of arterial endothelium by upregulation of chemokines.

Serum amyloid A receptor blockade and incorporation into high-density lipoprotein modulates its pro-inflammatory and pro-thrombotic activities on vascular endothelial cells

The acute phase protein serum amyloid A (SAA), a marker of inflammation, induces expression of pro-inflammatory and pro-thrombotic mediators including ICAM-1, VCAM-1, IL-6, IL-8, MCP-1 and tissue factor (TF) in both monocytes/macrophages and endothelial cells, and induces endothelial dysfunction—a precursor to atherosclerosis. In this study, we determined the effect of pharmacological inhibition of known SAA receptors on pro-inflammatory and pro-thrombotic activities of SAA in human carotid artery endothelial cells (HCtAEC). HCtAEC were pre-treated with inhibitors of formyl peptide receptor-like-1 (FPRL-1), WRW4; receptor for advanced glycation-endproducts (RAGE), (endogenous secretory RAGE; esRAGE) and toll-like receptors-2/4 (TLR2/4) (OxPapC), before stimulation by added SAA. Inhibitor activity was also compared to high-density lipoprotein (HDL), a known inhibitor of SAA-induced effects on endothelial cells. SAA significantly increased gene expression of TF, NFκB and TNF and protein levels of TF and VEGF in HCtAEC. These effects were inhibited to variable extents by WRW4, esRAGE and OxPapC either alone or in combination, suggesting involvement of endothelial cell SAA receptors in pro-atherogenic gene expression. In contrast, HDL consistently showed the greatest inhibitory action, and often abrogated SAA-mediated responses. Increasing HDL levels relative to circulating free SAA may prevent SAA-mediated endothelial dysfunction and ameliorate atherogenesis.

Serum amyloid A and inflammation in diabetic kidney disease and podocytes

Inflammatory pathways are central mechanisms in diabetic kidney disease (DKD). Serum amyloid A (SAA) is increased by chronic inflammation, but SAA has not been previously evaluated as a potential DKD mediator. The aims of this study were to determine whether SAA is increased in human DKD and corresponding mouse models and to assess effects of SAA on podocyte inflammatory responses. SAA was increased in the plasma of people with DKD characterized by overt proteinuria and inversely correlated with estimated glomerular filtration rate (creatinine-based CKD-EPI). SAA was also elevated in plasma of diabetic mouse models including type 1 diabetes (streptozotocin/C57BL/6) and type 2 diabetes (BTBR-ob/ob). SAA mRNA (Nephromine) was increased in human DKD compared with non-diabetic and/or glomerular disease controls (glomerular fold change 1.5, P=0.017; tubulointerstitium fold change 1.4, P=0.021). The kidneys of both diabetic mouse models also demonstrated increased SAA mRNA (quantitative real-time PCR) expression compared with non-diabetic controls (type 1 diabetes fold change 2.9; type 2 diabetes fold change 42.5, P=0.009; interaction by model P=0.57). Humans with DKD and the diabetic mouse models exhibited extensive SAA protein deposition in the glomeruli and tubulointerstitium in similar patterns by immunohistochemistry. SAA localized within podocytes of diabetic mice. Podocytes exposed to advanced glycation end products, metabolic mediators of inflammation in diabetes, increased expression of SAA mRNA (fold change 15.3, P=0.004) and protein (fold change 38.4, P=0.014). Podocytes exposed to exogenous SAA increased NF-κB activity, and pathway array analysis revealed upregulation of mRNA for NF-κB-dependent targets comprising numerous inflammatory mediators, including SAA itself (fold change 17.0, P=0.006). Inhibition of NF-κB reduced these pro-inflammatory responses. In conclusion, SAA is increased in the blood and produced in the kidneys of people with DKD and corresponding diabetic mouse models. Podocytes are likely to be key responder cells to SAA-induced inflammation in the diabetic kidney. SAA is a compelling candidate for DKD therapeutic and biomarker discovery.

Acute Phase Response: Implication in ST-segment Elevation Myocardial Infarction

We aimed to investigate the relation between serum inflammatory markers, 25OHvit-D3 and oxidative stress markers, namely paraoxonase1-arylesterase (PON1-ARE), total antioxidant status (TAS) and total oxidant status (TOS) in 30 male patients with ST-elevation myocardial infarction(STEMI) . There was negative correlation between tumor necrosis factor alpha and ARE; positive correlations between serum amyloid A(SAA) and oxidative stress index, SAA and TOS, 25OHvit-D3 and ARE. There was no statistically significant correlation between inflammation makers, oxidative stress markers and Gensini score. The main finding of our study was the tendency of inflammation markers, and oxidative stress markers, to change in relatively clear opposite directions in STEMI.

Serum amyloid A stimulates cultured endothelial cells to migrate and proliferate: inhibition by the multikinase inhibitor BIBF1120

In the present study, we tested whether serum amyloid A (SAA) protein, an established biomarker of inflammation, also plays a role in stimulating neovascularization. To evaluate this possibility, human carotid artery endothelial (HCtAE) cells were cultured and cellular migration and the proinflammatory and/or thrombotic activity of SAA (0, 1 or 10 μg/mL) on vascular endothelial cells was verified by determining gene regulation relative to control (in the absence of SAA). Exposure of HCtAE cells to SAA increased expression of the transcription factor nuclear factor-κB (NFKB), tumour necrosis factor (TNF) and pro-coagulative tissue factor (F3), and stimulated phosphorylation of the P65 subunit of the NFKB complex. Enhanced production of TNF and NFKB was paralleled by increased vascular endothelial growth factor (VEGF) mRNA and protein expression, as demonstrated by quantitative polymerase chain reaction, western blotting and ELISA. Administration of 10 μg/mL SAA enhanced endothelial cell migration (1.6-fold vs control), stimulated regrowth of HCtAE cells after mechanical injury (~1.2-fold vs control) and increased endothelial tube formation relative to control after 6 h. The SAA-mediated enhancement of endothelial cell migration, proliferation and tube formation were markedly inhibited by pretreatment of HCtAE cells with the multi-angiokinase receptor inhibitor BIBF1120 (100 nmol/L), although SAA-stimulated gene responses for F3 and NFKB were unaffected by 100 nmol/L BIBF1120 pretreatment. Overall, BIBF1120 inhibited the pro-angiogenic activity of SAA on vascular endothelial cells in this experimental model of inflammation.

A bidirectional relationship of oral-systemic responses: observations of systemic host responses in patients after full-mouth extractions

OBJECTIVE

This investigation tested the hypothesis that systemic inflammatory responses would be attenuated by minimizing the oral microbial burden in patients with moderate to severe periodontitis.

STUDY DESIGN

Patients (n = 73) scheduled for full-mouth extractions were categorized as case type I/II (gingivitis/mild periodontitis) or case type III/IV (moderate/severe periodontitis). Serum levels of acute phase proteins (APPs) and immunoglobulin G (IgG) antibody were assessed at baseline and through 1 year after extraction.

RESULTS

At baseline, the levels of multiple APPs (e.g., fibrinogen, C-reactive protein) and antibodies to periodontal pathogens were significantly higher with case type III/IV vs I/II. These differences were sustained 12 months after extractions for most APPs.

CONCLUSIONS

The results demonstrated that removal of disease by full-mouth extraction of teeth altered the overall burden of challenge to the host. Continued elevation in various APPs in the III/IV group suggested a potential underlying constitutive difference in systemic response characteristics of this population.

Proteomic analysis of plasma-purified VLDL, LDL, and HDL fractions from atherosclerotic patients undergoing carotid endarterectomy: identification of serum amyloid A as a potential marker

Apolipoproteins are very heterogeneous protein family, implicated in plasma lipoprotein structural stabilization, lipid metabolism, inflammation, or immunity. Obtaining detailed information on apolipoprotein composition and structure may contribute to elucidating lipoprotein roles in atherogenesis and to developing new therapeutic strategies for the treatment of lipoprotein-associated disorders. This study aimed at developing a comprehensive method for characterizing the apolipoprotein component of plasma VLDL, LDL, and HDL fractions from patients undergoing carotid endarterectomy, by means of two-dimensional electrophoresis (2-DE) coupled with Mass Spectrometry analysis, useful for identifying potential markers of plaque presence and vulnerability. The adopted method allowed obtaining reproducible 2-DE maps of exchangeable apolipoproteins from VLDL, LDL, and HDL. Twenty-three protein isoforms were identified by peptide mass fingerprinting analysis. Differential proteomic analysis allowed for identifying increased levels of acute-phase serum amyloid A protein (AP SAA) in all lipoprotein fractions, especially in LDL from atherosclerotic patients. Results have been confirmed by western blotting analysis on each lipoprotein fraction using apo AI levels for data normalization. The higher levels of AP SAA found in patients suggest a role of LDL as AP SAA carrier into the subendothelial space of artery wall, where AP SAA accumulates and may exert noxious effects.

Serum amyloid A inhibits dendritic cell apoptosis to induce glucocorticoid resistance in CD4(+) T cells

Mediators produced by the airway epithelium control the activation, recruitment, and survival of pulmonary dendritic cells (DC) that present antigen to CD4(+) T cells during the genesis and exacerbation of allergic asthma. The epithelial-derived acute phase protein, serum amyloid A (SAA), induces DC maturation and TH17 polarization. TH17 responses are associated with severe forms of allergic asthma that are poorly controlled by corticosteroids. We sought to determine whether SAA would enhance the survival of DC during serum starvation and could then contribute to the development of a glucocorticoid-resistant phenotype in CD4(+) T cells. Bone marrow-derived dendritic cells (BMDC) that were serum starved in the presence of SAA were protected from activation of caspase-3 and released less lactate dehydrogenase. In comparison with untreated serum-starved BMDC, treatment with SAA downregulated mRNA expression of the pro-apoptotic molecule Bim, increased production of the pro-survival heat shock protein 70 (HSP70), and induced secretion of pro-inflammatory cytokines. SAA-treated BMDC that were serum starved for 48 h remained capable of presenting antigen and induced OTII CD4(+) T cells to secrete IL-17A, IL-17F, IL-21, IL-22, and IFNγ in the presence of ovalbumin. IL-17A, IL-17F, IL-21, and IFNγ production occurred even when the CD4(+) T cells were treated with dexamethasone (Dex), whereas glucocorticoid treatment abolished cytokine secretion by T cells cocultured with untreated serum-starved BMDC. Measurement of Dex-responsive gene expression demonstrated CD4(+) T cells as the target of glucocorticoid hyperresponsiveness manifest as a consequence of BMDC stimulation by SAA. Finally, allergic airway disease induced by SAA and antigen inhalation was unresponsive to Dex treatment. Our results indicate that apo-SAA affects DC to both prolong their viability and increase their inflammatory potential under apoptosis-inducing conditions. These findings reveal mechanisms through which SAA enhances the CD4(+) T-cell-stimulating capacity of antigen-presenting cells that may actively participate in the pathogenicity of glucocorticoid-resistant lung disease.

Plasma proteomics of differential outcome to long-term therapy in children with idiopathic pulmonary arterial hypertension

PURPOSE

The prognosis for children with IPAH unresponsive to therapy is poor. We investigated the plasma proteome for a molecular basis of good versus poor outcome to long-term vasodilator therapy.

EXPERIMENTAL DESIGN

Plasma was collected at baseline or shortly after therapy initiation and following chronic vasodilator therapy, then divided into those with good outcome (n = 8), and those with a poor outcome (n = 7). To identify proteins unique to either outcome, we used differential gel electrophoresis and mass spectrometry. Results were confirmed by commercial enzyme-linked immunosorbent assay.

RESULTS

Before and after therapy, SAA-4 was 4-fold lower in those with good outcome compared to those with poor outcome, while serum paraoxonase/arylesterase-1 was increased 2-fold in those with good outcome versus poor outcome. After therapy, haptoglobin and hemopexin were 1.45- and 1.8-fold lower, respectively, in those with a good versus poor outcome. Among those with a good outcome, SAP was 1.3-fold lower prior to therapy.

CONCLUSIONS AND CLINICAL RELEVANCE

SAP and SAA-4 regulate circulating mononuclear phagocytes. As such, they may contribute to the differential response to chronic vasodilator therapy in the context of inflammation in IPAH.

Angiogenic factors and acute-phase proteins in serum samples of preeclampsia and HELLP patients: a matched-pair analysis

OBJECTIVES

To investigate the serum level distribution of angiogenic markers (PlGF, endoglin, sFlt-1) and acute-phase proteins (SAA, CRP) in patients with HELLP syndrome or preeclampsia (PE) including matched controls.

METHODS

The matching procedure revealed 46 controls for 23 HELLP cases, and 81 controls for 42 preeclamptic patients. Maternal serum concentrations were determined by immunoassays.

RESULTS

SAA and CRP levels were significantly higher in HELLP patients compared with controls. This finding was not observed in preeclamptic subgroup. Pro-angiogenic PlGF is significantly lower in PE and HELLP syndrome. Anti-angiogenic endoglin is significantly higher in PE and HELLP syndrome. The sFlt-1 analysis supports the anti-angiogenic shift in HELLP and preeclamptic patients, but with smaller differences between subgroups. The SAA/PlGF ratio showed the highest ROC value of all tested parameters in discrimination between HELLP and HELLP controls.

CONCLUSIONS

These findings support the concept that patients with HELLP syndrome have both an anti-angiogenic state and a pronounced inflammatory response, while patients with PE are characterized only by an anti-angiogenic shift.

Acute-phase serum amyloid A: perspectives on its physiological and pathological roles

Serum amyloid A (SAA), a protein originally of interest primarily to investigators focusing on AA amyloidogenesis, has become a subject of interest to a very broad research community. SAA is still a major amyloid research topic because AA amyloid, for which SAA is the precursor, is the prototypic model of in vivo amyloidogenesis and much that has been learned with this model has been applicable to much more common clinical types of amyloid. However, SAA has also become a subject of considerable interest to those studying (i) the synthesis and regulation of acute phase proteins, of which SAA is a prime example, (ii) the role that SAA plays in tissue injury and inflammation, a situation in which the plasma concentration of SAA may increase a 1000-fold, (iii) the influence that SAA has on HDL structure and function, because during inflammation the majority of SAA is an apolipoprotein of HDL, (iv) the influence that SAA may have on HDL's role in reverse cholesterol transport, and therefore, (v) SAA's potential role in atherogenesis. However, no physiological role for SAA, among many proposed, has been widely accepted. None the less from an evolutionary perspective SAA must have a critical physiological function conferring survival-value because SAA genes have existed for at least 500 million years and SAA's amino acid sequence has been substantially conserved. An examination of the published literature over the last 40 years reveals a great deal of conflicting data and interpretation. Using SAA's conserved amino acid sequence and the physiological effects it has while in its native structure, namely an HDL apolipoprotein, we argue that much of the confounding data and interpretation relates to experimental pitfalls not appreciated when working with SAA, a failure to appreciate the value of physiologic studies done in the 1970-1990 and a current major focus on putative roles of SAA in atherogenesis and chronic disease. When viewed from an evolutionary perspective, published data suggest that acute-phase SAA is part of a systemic response to injury to recycle and reuse cholesterol from destroyed and damaged cells. This is accomplished through SAA's targeted delivery of HDL to macrophages, and its suppression of ACAT, the enhancement of neutral cholesterol esterase and ABC transporters in macrophages. The recycling of cholesterol during serious injury, when dietary intake is restricted and there is an immediate and critical requirement of cholesterol in the generation of myriads of cells involved in inflammation and repair responses, is likely SAA's important survival role. Data implicating SAA in atherogenesis are not relevant to its evolutionary role. Furthermore, in apoE(-/-) mice, domains near the N- and C- termini of SAA inhibit the initiation and progression of aortic lipid lesions illustrating the conflicting nature of these two sets of data.

The effect of poloxamer 407 on the functional properties of HDL in mice

Objectives

There is an inverse relationship between high-density lipoprotein (HDL) and heart disease. HDL possesses not only both antioxidant and anti-inflammatory properties, but also anti-thrombotic and endothelial function-promoting qualities. However, it is not only the serum concentration of HDL that is important, but also the ‘functional’ quality of the HDL. The objective was to determine the functional status of HDL in a well-established mouse model of dyslipidaemia and atherosclerosis induced by the administration of a block copolymer (poloxamer 407; P-407).

Methods

C57BL/6 mice were administered a single intraperitoneal dose of P-407 (0.5 g/kg) and blood was collected at 24 h post-dosing. HDL was isolated from controls (control HDL) and P-407-treated (P-407 HDL) mice and used to test its anti-inflammatory properties in vitro. Additionally, antioxidant enzymes associated with HDL, namely, platelet activating factor-acetylhydrolase (PAF-AH) and paraoxonase (PON), were evaluated for any potential reduction in their biological activity.

Key findings

A single injection of P-407 in C57BL/6 mice resulted in a marked decrease in the levels of HDL-cholesterol and phospholipids. HDL particle size significantly increased, primarily due to remodelling of HDL with triglyceride. It was demonstrated that (i) long-chain saturated fatty acids were higher and the n-3/n-6 fatty acid ratio was significantly lower for P-407 HDL compared with control HDL, and (ii) P-407 HDL lost its capacity to inhibit tumour necrosis factor-α (TNF-α)-induced vascular cell adhesion molecule-1 (VCAM-1) expression compared with control HDL. Additionally, P-407 HDL was not able to neutralize lipopolysaccharide and inhibit subsequent TNF-α production compared with control HDL. The biological activity of platelet-activating factor acetylhydrolase (PAF-AH) and paraoxonase (PON) decreased in direct proportion to the circulating levels of both HDL-cholesterol and apolipoprotein (apoA-1).

Conclusions

Combination of previously reported findings in P-407-treated mice, such as (i) production of both oxidized LDL and malondialdehyde, and (ii) profound elevations in the soluble forms of intercellular adhesion molecule-1 (ICAM-1), VCAM-1, and E-selectin, with the present results, would strongly suggest that HDL in P-407-treated mice is rendered dysfunctional. Thus, these findings help to explain why P-407-treated mice begin to form aortic atherosclerotic lesions about one month after initiating P-407 treatment.