Complement in atherosclerosis: friend or foe?

Diagnostic and prognostic value of mannan-binding lectin associated protein (MAp19) for functionally relevant coronary artery disease

BACKGROUND

This study aimed to evaluate the diagnostic and prognostic potential of MAp19, a regulating component of the lectin pathway of the complement system, in patients with suspected functionally relevant coronary artery disease (fCAD) as well as the determinants of MAp19 levels.

METHODS

The presence of fCAD was adjudicated using myocardial perfusion imaging with single-photon emission tomography and, where available, coronary angiography. MAp19 levels were measured in participants at rest, at peak stress tests, and two hours after the stress. The study also tracked major cardiovascular events, including non-fatal myocardial infarction and cardiovascular death, over a five-year follow-up period.

RESULTS

Among the 1,571 patients analyzed (32.3 % women), fCAD was identified in 462 individuals (29.4 %). MAp19 demonstrated no diagnostic significance, yielding an area under the curve (AUC) of 0.51 (0.47-0.55). Throughout the five-year follow-up, 107 patients (6.8 %) experienced non-fatal myocardial infarctions, 99 (6.3 %) had cardiovascular death, 194 (12.3 %) experienced all cause death and 50 (3.1 %) suffered a stroke. Cox and Kaplan-Meier analysis confirmed prognostic value of MAp19 for myocardial infarction, but not for cardiovascular death. Significant increases in the concentration of MAp19 were observed during bicycle (p = 0.001) and combined stress tests (p = 0.001).

CONCLUSION

MAp19 demonstrated an association with the risk of myocardial infarction. Increases in MAp19 concentration were observed during bicycle and combined stress-tests.

Association of the Complement System with Subclinical Atherosclerosis in Psoriasis: Findings from an Observational Cohort Study

Psoriasis is a chronic and inflammatory disease that affects the skin and joints and is associated with multiple comorbidities and cardiovascular risk factors. Consequently, patients with psoriasis have an increased risk of cardiovascular diseases such as atherosclerosis, a chronic pathology that shares common inflammatory and immune-response mechanisms with psoriasis, including vascular inflammation and complement activation. To better understand the relationship between atherosclerosis and psoriasis, a proteomics study followed by a bioinformatics analysis was carried out, with a subsequent validation step using ELISA and western blotting. When the plasma from patients with psoriasis alone was compared with that from patients with psoriasis and atherosclerosis, 31 proteins of interest related to the complement system and oxygen transport were identified. After the validation phase, 11 proteins appeared to define the presence of subclinical atherosclerosis in patients with psoriasis, indicating the importance of complement cascades in the development of atherosclerotic plaques in individuals with psoriasis. These results are a step forward in understanding the pathological pathways implicated in the cardiovascular risk associated with this population, which may represent an interesting starting point for developing predictive tools that improve the follow-up of these patients and design more effective therapies.

The relationship between complement C1q and coronary plaque vulnerability based on optical coherence tomography analysis

To determine the association between complement C1q and vulnerable plaque morphology among coronary artery disease (CAD) patients. We conducted a retrospective observational study of 221 CAD patients admitted to The Second Affiliated Hospital of Xi'an Jiaotong University. Intravascular optical coherence tomography was utilized to describe the culprit plaques' morphology. Using logistic regression analysis to explore the correlation between C1q and vulnerable plaques, and receiver operator characteristic (ROC) analysis assess the predictive accuracy. As reported, the complement C1q level was lower in ACS patients than CCS patients (18.25 ± 3.88 vs. 19.18 ± 4.25, P = 0.045). The low complement-C1q-level group was more prone to develop vulnerable plaques. In lipid-rich plaques, the complement C1q level was positively correlated with the thickness of fibrous cap (r = 0.480, P = 0.041). Univariate and multivariate logistic regression analyses suggested that complement C1q could be an independent contributor to plaques' vulnerability. For plaque rupture, erosion, thrombus, and cholesterol crystals, the areas under the ROC curve of complement C1q level were 0.873, 0.816, 0.785, and 0.837, respectively (P < 0.05 for all). In CAD patients, the complement C1q could be a valuable indicator of plaque vulnerability.

High Level of Serum Complement C3 Expression is Associated with Postoperative Vasculopathy Progression in Moyamoya Disease

Background

The immune system plays an important role in the onset and development of moyamoya disease (MMD), but the specific mechanisms remain unclear. This study aimed to explore the relationship between the expression of complements and immunoglobulin in serum and progression of MMD.

Methods

A total of 84 patients with MMD and 70 healthy individuals were enrolled. Serum immunoglobulin and complement C3 and C4 expression were compared between healthy individuals and MMD patients. Follow-up was performed at least 6 months post-operation. Univariate and multivariate analysis after adjusting different covariates were performed to explore predictive factors associated with vasculopathy progression. A nomogram basing on the results of multivariate analysis was established to predict vasculopathy progression.

Results

Compared to healthy individuals, MMD patients had significantly lower expression of serum complements C3 (P = 0.003*). Among MMD patients, C3 was significantly lower in those with late-stage disease (P = 0.001*). Of 84 patients, 27/84 (32.1%) patients presented with vasculopathy progression within a median follow-up time of 13.0 months. Age (P=0.006*), diastolic blood pressure (P=0.004*) and serum complement C3 expression (P=0.015*) were associated with vasculopathy progression after adjusting different covariables.

Conclusion

Complement C3 is downregulated in moyamoya disease and decreases even further in late-Suzuki stage disease. Age, diastolic blood pressure and serum complement C3 expression are associated with vasculopathy progression, suggesting that the complement might be involved in the development of moyamoya disease.

The role of immune system in atherosclerosis: Molecular mechanisms, controversies, and future possibilities

Numerous cardiovascular disorders have atherosclerosis as their pathological underpinning. Numerous studies have demonstrated that, with the aid of pattern recognition receptors, cytokines, and immunoglobulins, innate immunity, represented by monocytes/macrophages, and adaptive immunity, primarily T/B cells, play a critical role in controlling inflammation and abnormal lipid metabolism in atherosclerosis. Additionally, the finding of numerous complement components in atherosclerotic plaques suggests yet again how heavily the immune system controls atherosclerosis. Therefore, it is essential to have a thorough grasp of how the immune system contributes to atherosclerosis. The specific molecular mechanisms involved in the activation of immune cells and immune molecules in atherosclerosis, the controversy surrounding some immune cells in atherosclerosis, and the limitations of extrapolating from relevant animal models to humans were all carefully reviewed in this review from the three perspectives of innate immunity, adaptive immunity, and complement system. This could provide fresh possibilities for atherosclerosis research and treatment in the future.

Serum multi-omics analysis in hindlimb unloading mice model: Insights into systemic molecular changes and potential diagnostic and therapeutic biomarkers

Microgravity, in space travel and prolonged bed rest conditions, induces cardiovascular deconditioning along with skeletal muscle mass loss and weakness. The findings of microgravity research may also aid in the understanding and treatment of human health conditions on Earth such as muscle atrophy, and cardiovascular diseases. Due to the paucity of biomarkers and the unknown underlying mechanisms of cardiovascular and skeletal muscle deconditioning in these environments, there are insufficient diagnostic and preventative measures. In this study, we employed hindlimb unloading (HU) mouse model, which mimics astronauts in space and bedridden patients, to first evaluate cardiovascular and skeletal muscle function, followed by proteomics and metabolomics LC-MS/MS-based analysis using serum samples. Three weeks of unloading caused changes in the function of the cardiovascular system in c57/Bl6 mice, as seen by a decrease in mean arterial pressure and heart weight. Unloading for three weeks also changed skeletal muscle function, causing a loss in grip strength in HU mice and atrophy of skeletal muscle indicated by a reduction in muscle mass. These modifications were partially reversed by a two-week recovery period of reloading condition, emphasizing the significance of the recovery process. Proteomics analysis revealed 12 dysregulated proteins among the groups, such as phospholipid transfer protein, Carbonic anhydrase 3, Parvalbumin alpha, Major urinary protein 20 (Mup20), Thrombospondin-1, and Apolipoprotein C-IV. On the other hand, metabolomics analysis showed altered metabolites among the groups such as inosine, hypoxanthine, xanthosine, sphinganine, l-valine, 3,4-Dihydroxyphenylglycol, and l-Glutamic acid. The joint data analysis revealed that HU conditions mainly impacted pathways such as ABC transporters, complement and coagulation cascades, nitrogen metabolism, and purine metabolism. Overall, our results indicate that microgravity environment induces significant alterations in the function, proteins, and metabolites of these mice. These observations suggest the potential utilization of these proteins and metabolites as novel biomarkers for assessing and mitigating cardiovascular and skeletal muscle deconditioning associated with such conditions.

ITGB2 is a central hub-gene associated with inflammation and early fibro-atheroma development in a swine model of atherosclerosis

Background and aim

The complex dynamic interplay between different biological pathways involved in atherosclerosis development has rendered the identification of specific therapeutic targets a challenging quest. We aimed to identify specific genes and mechanistic pathways associated with the early development of fibro-atheromas in a swine model of atherosclerosis.

Methods

The Wisconsin Miniature Swine™ model of Familial Hypercholesterolemia (WMS-FH, n = 11) and genetically related WMS controls (WMS-N, n = 11) were used. The infrarenal aorta was harvested from both groups for histopathologic and transcriptomic profiling at 12 months. Bioinformatic analysis was performed to identify hub genes and pathways central to disease pathophysiology. The expression of ITGB2, the top ranked hub gene, was manipulated in cell culture and the expression of interconnected genes was tested.

Results

Fibro-atheromatous lesions were documented in all WMS-FH aortic tissues and displayed internal elastic lamina (IEL) disruption, significant reduction of myofibroblast presence and disorganized collagen deposition. No fibro-atheromas were observed in the control group. A total of 266 differentially expressed genes (DEGs) were upregulated in WMS-FH aortic tissues, while 29 genes were downregulated. Top identified hub genes included ITGB2, C1QA, LCP2, SPI1, CSF1R, C5AR1, CTSS, MPEG1, C1QC, and CSF2RB. Overexpression of ITGB2 resulted in elevated expression of other interconnected genes expressed in porcine endothelial cells.

Conclusion

In a swine translational model of atherosclerosis, transcriptomic analysis identified ITGB2 as a central hub gene associated inflammation and early fibroatheroma development making it a potential therapeutic target at this stage of disease.

Cell-autonomous regulation of complement C3 by factor H limits macrophage efferocytosis and exacerbates atherosclerosis

Complement factor H (CFH) negatively regulates consumption of complement component 3 (C3), thereby restricting complement activation. Genetic variants in CFH predispose to chronic inflammatory disease. Here, we examined the impact of CFH on atherosclerosis development. In a mouse model of atherosclerosis, CFH deficiency limited plaque necrosis in a C3-dependent manner. Deletion of CFH in monocyte-derived inflammatory macrophages propagated uncontrolled cell-autonomous C3 consumption without downstream C5 activation and heightened efferocytotic capacity. Among leukocytes, Cfh expression was restricted to monocytes and macrophages, increased during inflammation, and coincided with the accumulation of intracellular C3. Macrophage-derived CFH was sufficient to dampen resolution of inflammation, and hematopoietic deletion of CFH in atherosclerosis-prone mice promoted lesional efferocytosis and reduced plaque size. Furthermore, we identified monocyte-derived inflammatory macrophages expressing C3 and CFH in human atherosclerotic plaques. Our findings reveal a regulatory axis wherein CFH controls intracellular C3 levels of macrophages in a cell-autonomous manner, evidencing the importance of on-site complement regulation in the pathogenesis of inflammatory diseases.

Plasma factor D is cross-sectionally associated with low-grade inflammation, endothelial dysfunction and cardiovascular disease: The Maastricht study

BACKGROUND AND AIMS

The complement system, particularly the alternative complement pathway, may contribute to vascular damage and development of cardiovascular disease (CVD). We investigated the association of factor D, the rate-limiting protease in alternative pathway activation, with adverse cardiovascular outcomes.

METHODS

In 2947 participants (50.6% men, 59.9 ± 8.2 years, 26.5% type 2 diabetes [T2D], oversampled) we measured markers of low-grade inflammation (LGI, composite score, in SD) and, endothelial dysfunction (ED, composite score, in SD), carotid intima-media thickness (cIMT, μm), ankle-brachial index (ABI), CVD (yes/no) and plasma concentrations of factor D (in SD). Associations were estimated using multiple linear and logistic regression, adjusting for demographic, lifestyle, and dietary factors.

RESULTS

Factor D (per SD) significantly associated with LGI (0.171 SD [0.137; 0.205]), ED (0.158 SD [0.123; 0.194]) and CVD (OR 1.15 [1.04; 1.27]) but not significantly with cIMT (-6.62 μm [-13.51; 0.27]) or ABI (-0.003 [-0.007; 0.001]). Interaction analyses show that factor D more strongly associated with ED in non-diabetes (0.237 SD [0.189; 0.285] than in T2D (0.095 SD [0.034; 0.157]), pinteraction <0.05. These results were largely corroborated by additional analyses with C3 and C3a. In contrast, factor D inversely associated with cIMT in non-diabetes (-13.37 μm [-21.84; -4.90]), but not in T2D (4.49 [-7.91; 16.89]), pinteraction <0.05.

CONCLUSIONS

Plasma factor D is independently associated with LGI, ED, and prevalent CVD but not with ABI or cIMT. Hence, greater plasma factor D concentration in CVD may potentially induce complement activation which, in turn, might contribute to further disease progression via a process that may involve inflammation and endothelial dysfunction but was not directly related to atherosclerosis or arterial injury. The observation that, in participants without diabetes, factor D associated with worse ED but smaller cIMT warrants further investigation.

Epigenetic BET reader inhibitor apabetalone (RVX-208) counters proinflammatory aortic gene expression in a diet induced obesity mouse model and in human endothelial cells

BACKGROUND AND AIMS

Obese patients are at risk for type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). A lipid-rich diet promotes arterial changes by inducing hypertension, oxidative stress, and inflammation. Bromodomain and extraterminal (BET) proteins contribute to endothelial and immune cell activation in vitro and in atherosclerosis mouse models. We aim to determine if BET inhibition can reduce lipid-rich diet-induced vascular inflammation in mice.

METHODS

Body weight, serum glucose and lipid levels were measured in mice fed a high-fat diet (HFD) or low-fat diet (LFD) for 6 weeks and at study termination. BET inhibitors apabetalone and JQ1 were co-administered with the HFD for additional 16 weeks. Aortic gene expression was analyzed post necropsy by PCR, Nanostring nCounter® Inflammation Panel and bioinformatics pathway analysis. Transcription changes and BRD4 chromatin occupancy were analyzed in primary human endothelial cells in response to TNFα and apabetalone.

RESULTS

HFD induced weight gain, visceral obesity, high fasting blood glucose, glucose intolerance and insulin resistance compared to LFD controls. HFD upregulated the aortic expression of 47 genes involved in inflammation, innate immunity, cytoskeleton and complement pathways. Apabetalone and JQ1 treatment reduced HFD-induced aortic expression of proinflammatory genes. Congruently, bioinformatics predicted enhanced signaling by TNFα in the HFD versus LFD aorta, which was countered by BETi treatment. TNFα-stimulated human endothelial cells had increased expression of HFD-sensitive genes and higher BRD4 chromatin occupancy, which was countered by apabetalone treatment.

CONCLUSIONS

HFD induces vascular inflammation in mice through TNFα signaling. Apabetalone treatment reduces this proinflammatory phenotype, providing mechanistic insight into how BET inhibitors may reduce CVD risk in obese patients.

Decoding the transcriptome of calcified atherosclerotic plaque at single-cell resolution

Atherogenesis involves an interplay of inflammation, tissue remodeling and cellular transdifferentiation (CTD), making it especially difficult to precisely delineate its pathophysiology. Here we use single-cell RNA sequencing and systems-biology approaches to analyze the transcriptional profiles of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) in calcified atherosclerotic core (AC) plaques and patient-matched proximal adjacent (PA) portions of carotid artery tissue from patients undergoing carotid endarterectomy. Our results reveal an anatomic distinction whereby PA cells express inflammatory mediators, while cells expressing matrix-secreting genes occupy a majority of the AC region. Systems biology analysis indicates that inflammation in PA ECs and VSMCs may be driven by TNFa signaling. Furthermore, we identify POSTN, SPP1 and IBSP in AC VSMCs, and ITLN1, SCX and S100A4 in AC ECs as possible candidate drivers of CTD in the atherosclerotic core. These results establish an anatomic framework for atherogenesis which forms the basis for exploration of a site-specific strategy for disruption of disease progression.

Single-cell RNA sequencing and systems biology are used to profile the human vascular cell populations in calcified atherosclerotic core plaques from carotid endarterectomy samples, showing an anatomic distinction between gene expression of inflammatory versus matrix-secreting factors.

Therapeutic Intervention with Anti-Complement Component 5 Antibody Does Not Reduce NASH but Does Attenuate Atherosclerosis and MIF Concentrations in Ldlr-/-.Leiden Mice

Background: Chronic inflammation is an important driver in the progression of non-alcoholic steatohepatitis (NASH) and atherosclerosis. The complement system, one of the first lines of defense in innate immunity, has been implicated in both diseases. However, the potential therapeutic value of complement inhibition in the ongoing disease remains unclear. Methods: After 20 weeks of high-fat diet (HFD) feeding, obese Ldlr-/-.Leiden mice were treated twice a week with an established anti-C5 antibody (BB5.1) or vehicle control. A separate group of mice was kept on a chow diet as a healthy reference. After 12 weeks of treatment, NASH was analyzed histopathologically, and genome-wide hepatic gene expression was analyzed by next-generation sequencing and pathway analysis. Atherosclerotic lesion area and severity were quantified histopathologically in the aortic roots. Results: Anti-C5 treatment considerably reduced complement system activity in plasma and MAC deposition in the liver but did not affect NASH. Anti-C5 did, however, reduce the development of atherosclerosis, limiting the total lesion size and severity independently of an effect on plasma cholesterol but with reductions in oxidized LDL (oxLDL) and macrophage migration inhibitory factor (MIF). Conclusion: We show, for the first time, that treatment with an anti-C5 antibody in advanced stages of NASH is not sufficient to reduce the disease, while therapeutic intervention against established atherosclerosis is beneficial to limit further progression.

Overactivation of the complement system may be involved in intrarenal arteriolar lesions in IgA nephropathy

Introduction

IgA nephropathy (IgAN) encompasses a wide range of clinical and histology features. Some patients present without hematuria, with or without hypertension, still rapidly progress in renal function. Renal pathology of this part of patients were predominant intrarenal arteriolar lesions, rarely presented glomerular proliferative lesions. We aim to investigate the clinical and pathological characteristics and prognosis of these IgAN patients and initially explore whether the abnormal activation of complement is involved in the intrarenal arteriolar lesions of IgAN.

Methods

A total of 866 patients with renal biopsy-proven IgAN diagnosed at Beijing Anzhen Hospital were recruited. IgAN patients without intrarenal arteriolar lesions and proliferative lesions were excluded (n = 115), the rest were divided into arteriolar lesions group (n = 202) and proliferative lesions group (n = 549). Among them, 255 patients were regularly followed up for at least 1 year. Renal biopsy tissues of 104 IgAN patients were stained for complement components by immunohistochemistry and immunofluorescence.

Results

Compared with proliferative lesions group, the arteriolar lesions group experienced high percentage of hypertension (p = 0.004), low percentage of gross hematuria (p = 0.001), microscopic hematuria (p < 0.001) and less initial proteinuria (p = 0.033). Renal survival between the two groups was not significantly different (p = 0.133). MBL, C4d, FH and FHR5, C3c, and MAC deposited on intrarenal arteriole in arteriolar lesions group. Compare with the proliferative lesion group, the arteriolar lesions group exhibited a higher intensity of C3c deposition on the intrarenal arterioles (p = 0.048). C3c and CD31 co-deposited on intrarenal arterioles area in patients with intrarenal arteriolar lesions.

Conclusion

Renal survival of the IgAN patients in arteriolar lesions group was not better than those in proliferative lesions group. Abnormal activation of complement may be involved in the pathogenesis of arteriolar damage through the injury of endothelial cells in this clinical phenotype of IgAN.

Extent of vascular plaque predicts future cardiovascular events in patients with systemic lupus erythematosus

OBJECTIVE

Patients with SLE have increased prevalence of clinical cardiovascular disease (CVD) and subclinical atherosclerosis. Although 30-40% of patients with SLE have vascular plaque on ultrasound scanning, this study is the first to consider the relationship between total burden of plaque and subsequent CVD risk.

METHODS

One hundred patients with SLE and without any previous clinical CVD underwent vascular ultrasound scans of both carotid and both common femoral bifurcations between 2011 and 2013. Clinical, serological, demographic and treatment data were collected at baseline. Patients were followed till 2020 to identify those who developed new onset coronary disease or stroke. Statistical analysis to identify factors associated with increased risk of developing CVD events was carried out.

RESULTS

Thirty-six patients had plaque at baseline. During follow-up five patients (all had baseline plaque) developed coronary disease and two, without baseline plaque, developed lacunar strokes. Mean (s.d.) age of these patients was 46.5 (4.5) years. Patients with three or more baseline bifurcations with plaque were 10 times more likely to develop CVD than those with 0-2 bifurcations with plaques (OR 9.9, P = 0.009). TPA > 16mm2 was associated with six-fold increased risk of CVD (OR = 6.44, P = 0.028). Patients with disease duration > 14 years were more likely than those with disease duration < 14 years to develop CVD (OR 8.3 P = 0.043).

CONCLUSIONS

The number of bifurcations with plaque and TPA in patients with SLE may be valuable in assessing risk of CVD and deciding on clinical measures to reduce this risk.

Involvement of enhanced expression of classical complement C1q in atherosclerosis progression and plaque instability: C1q as an indicator of clinical outcome

Activation of the classical complement pathway plays a major role in regulating atherosclerosis progression, and it is believed to have both proatherogenic and atheroprotective effects. This study focused on C1q, the first protein in the classical pathway, and examined its potentialities of plaque progression and instability and its relationship with clinical outcomes. To assess the localization and quantity of C1q expression in various stages of atherosclerosis, immunohistochemistry, western blotting, and real-time polymerase chain reaction (PCR) were performed using abdominal aortas from eight autopsy cases. C1q immunoreactivity in relation to plaque instability and clinical outcomes was also examined using directional coronary atherectomy (DCA) samples from 19 patients with acute coronary syndromes (ACS) and 18 patients with stable angina pectoris (SAP) and coronary aspirated specimens from 38 patients with acute myocardial infarction. C1q immunoreactivity was localized in the extracellular matrix, necrotic cores, macrophages and smooth muscle cells in atherosclerotic lesions. Western blotting and real-time PCR illustrated that C1q protein and mRNA expression was significantly higher in advanced lesions than in early lesions. Immunohistochemical analysis using DCA specimens revealed that C1q expression was significantly higher in ACS plaques than in SAP plaques. Finally, immunohistochemical analysis using thrombus aspiration specimens demonstrated that histopathological C1q in aspirated coronary materials could be an indicator of poor medical condition. Our results indicated that C1q is significantly involved in atherosclerosis progression and plaque instability, and it could be considered as one of the indicators of cardiovascular outcomes.

Plasma Proteomic Changes of Atherosclerosis after Exercise in ApoE Knockout Mice

Atherosclerosis is the preliminary cause of coronary artery disease, one of the diseases that account for the largest number of fatal mortalities. Physical activity is an effective strategy to restrain atherosclerosis from deterioration. Evidence indicated that changes in the proteomic profile are highly associated with atherosclerosis development, but the mechanism behind exercise for atherosclerosis amelioration has not yet been investigated from a proteomics perspective. Hence, the proteomic profiles could further elucidate the systematic effects of exercise intervention on ApoE knockout atherosclerotic model and high-fat-diet intervention. In the current study, Apoeem1Narl/Narl mice were randomly allocated into a normal diet (ND), Western diet (WD), and WD with 12-week exercise intervention (WD EX) groups. The plasma proteome between WD and WD EX groups demonstrate the significant difference, and ten major pathways, including cardiovascular disease (CVD)–hematological disease, inflammatory disease, infectious diseases, inflammatory response, cell-to-cell signaling and interaction, connective tissue disorders_inflammatory disease, metabolic disease_organismal injury and abnormalities, cell-to-cell signaling and interaction, connective tissue disorders_inflammatory disease, and endocrine system disorders_gastrointestinal disease, etc., were generated by the IPA analysis. The 15 proteins (MYOCD, PROS1, C2, SERPINA10, CRP, F5, C5, CFB, FGG, CFH, F12, PRDX2, PROZ, PPIA, and HABP2) critically involved in CVD–hematological disease pathway showed significant difference between WD and WD EX groups. In current study, exercise could significantly alleviate the significantly elevated C5 and inflammation induced by the WD group in accordance with amelioration of atherosclerosis. Therefore, exercise could mitigate chemotaxis through the modulation of the C5 level and innate immunity, thereby alleviating the pathogenesis of atherosclerosis in Western-diet-induced obese mice.

Pharmacological Inhibition of CETP (Cholesteryl Ester Transfer Protein) Increases HDL (High-Density Lipoprotein) That Contains ApoC3 and Other HDL Subspecies Associated With Higher Risk of Coronary Heart Disease

Supplemental Digital Content is available in the text.

Plasma total HDL (high-density lipoprotein) is a heterogeneous mix of many protein-based subspecies whose functions and associations with coronary heart disease vary. We hypothesize that increasing HDL by CETP (cholesteryl ester transfer protein) inhibition failed to reduce cardiovascular disease risk, in part, because it increased dysfunctional subspecies associated with higher risk such as HDL that contains apoC3.

Proteomic analysis of extracellular vesicles enriched serum associated with future ischemic stroke

Identifying new biomarkers beyond the established risk factors that make it possible to predict and prevent ischemic stroke has great significance. Extracellular vesicles are powerful cell‒cell messengers, containing disease-specific biomolecules, which makes them powerful diagnostic candidates. Therefore, this study aimed to identify proteins derived from extracellular vesicles enriched serum related to future ischemic stroke events, using a proteomic method. Of Japanese subjects who voluntarily participated in health checkups at our institute a number of times, 10 subjects (6 males and 4 females, age: 64.2 ± 3.9 years) who developed symptomatic ischemic stroke (7.3 ± 4.4 years’ follow-up) and 10 age‒sex matched controls without brain lesions (6.7 ± 2.8 years’ follow-up) were investigated. Extracellular vesicles enriched fractions were derived from serum collected at the baseline visit. Differentially expressed proteins were evaluated using isobaric tagging for relative and absolute protein quantification (iTRAQ)-based proteomic analysis. Of the 29 proteins identified, alpha-2-macroglobulin, complement C1q subcomponent subunit B, complement C1r subcomponent, and histidine-rich glycoprotein were significantly upregulated (2.21-, 2.15-, 2.24-, and 2.16-fold, respectively) in subjects with future ischemic stroke, as compared with controls. Our study supports the concept of serum-derived extracellular vesicles enriched fractions as biomarkers for new-onset stroke. These proteins may be useful for prediction or for targeted therapy.

Screening and bioinformatics analysis of key biomarkers in acute myocardial infarction

Acute myocardial infarction (AMI) is the most severe manifestation of coronary artery disease. Considerable efforts have been made to elucidate its etiology and pathology, but the genetic factors that play a decisive role in the occurrence of AMI are still unclear. To determine the molecular mechanism of the occurrence and development of AMI, four microarray datasets, namely, GSE29111, GSE48060, GSE66360, and GSE97320, were downloaded from the Gene Expression Omnibus (GEO) database. We analyzed the four GEO datasets to obtain the differential expression genes (DEGs) of patients with AMI and patients with non-AMI and then performed gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and Protein-protein interaction (PPI) network analysis. A total of 41 DEGs were identified, including 39 upregulated genes and 2 downregulated genes. The enriched functions and pathways of the DEGs included the inflammatory response, neutrophil chemotaxis, immune response, extracellular space, positive regulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcription factor activity, response to lipopolysaccharide, receptor for advanced glycation end products (RAGE) receptor binding, innate immune response, defense response to bacterium, and receptor activity. The cytoHubba plug-in in Cytoscape was used to select the most significant hub gene from the PPI network. Ten hub genes were identified, and GO enrichment analysis revealed that these genes were mainly enriched in inflammatory response, neutrophil chemotaxis, immune response, RAGE receptor binding, and extracellular region. In conclusion, this study integrated four datasets and used bioinformatics methods to analyze the gene chips of AMI samples and control samples and identified DEGs that may be involved in the occurrence and development of AMI. The study provides reliable molecular biomarkers for AMI screening, diagnosis, and prognosis.

SARS-CoV-2 and Atherosclerosis: Should COVID-19 Be Recognized as a New Predisposing Cardiovascular Risk Factor?

At the beginning of the COVID-19 pandemic, the lung was recognized as the main target organ; now, new evidence suggests that SARS-CoV-2 infection leads to vascular disease. In a previous review, we supposed a bidirectional link between endothelial dysfunction and COVID-19, identifying atherosclerosis as having a crucial role in its pathogenesis. Atherosclerosis with an existing endothelial dysfunction may worsen COVID-19 manifestations, leading to adverse outcomes, as largely reported. However, COVID-19 may be the trigger factor in the progression of the atherosclerotic process up to making it clinically manifest. The thrombotic complications can involve not only the atherosclerotic plaque, but also the durability of the surgical device implanted to treat a pre-existing coronary artery disease as recently reported. The burden of the disease makes necessary a long-term stratification of patients, revising drastically targeted therapy among others.

Hyperhomocysteinemia as an Independent Risk Factor for Coronary Heart Disease. Comparison with Conventional Risk Factors

The present study was designed to evaluate the strength of association of raised plasma homocysteine concentration as a risk factor for coronary heart disease independent of conventional risk factor. It was a case control study conducted at Punjab Institute of Cardiology Lahore. A total of 210 subjects aged 25 to 60 years comprising of 105 newly admitted patients of CHD as cases and 105 age and sex matched healthy individuals with no history of CHD as control were recruited for the study. Fasting blood samples were obtained from cases and controls. Plasma homocysteine was analyzed by fluorescence polarization immunoassay (FPIA) method on automated immunoassay analyzer (Abbott IMX). Total cholesterol, triglyceride and HDL cholesterol were analyzed using calorimetric kit methods. The concentration of LDL cholesterol was calculated using Friedewald formula. The patients were also assessed for traditional risk factors such as age, sex, family history of CVD, hypertension, smoking and physical activity, and were compared with control subjects. The collected data was entered in SPSS version 24 for analysis and interpretation.The mean age in controls and experimental groups were 43.00± 8.42 years and 44.72± 8.59 years with statistically same distribution (p- value= 0.144). The mean plasma homocysteine for cases was 22.33± 9.22 µmol/L where as it was 12.59±3.73 µmol/L in control group. Highly significant difference was seen between the mean plasma level of homocysteine in cases and controls (p˂0.001).Simple logistic regression indicates a strong association of coronary heart disease with hyperhomocysteinemia (OR 7.45), which remained significantly associated with coronary heart disease by multivariate logistic regression (OR 7.10, 95%C1 3.12-12.83, p=0.000). The present study concludes that elevated levels of Plasma homocysteine is an independent risk factor for coronary heart disease independent of conventional risk factors and can be used as an indicator for predicting the future possibility for the onset of CVD.

Apolipoprotein Signature of HDL and LDL from Atherosclerotic Patients in Relation with Carotid Plaque Typology: A Preliminary Report

In the past years, it has become increasingly clear that the protein cargo of the different lipoprotein classes is largely responsible for carrying out their various functions, also in relation to pathological conditions, including atherosclerosis. Accordingly, detailed information about their apolipoprotein composition and structure may contribute to the revelation of their role in atherogenesis and the understanding of the mechanisms that lead to atherosclerotic degeneration and toward vulnerable plaque formation. With this aim, shotgun proteomics was applied to identify the apolipoprotein signatures of both high-density and low-density lipoproteins (HDL and LDL) plasma fractions purified from healthy volunteers and atherosclerotic patients with different plaque typologies who underwent carotid endarterectomy. By this approach, two proteins with potential implications in inflammatory, immune, and hemostatic pathways, namely, integrin beta-2 (P05107) and secretoglobin family 3A member 2 (Q96PL1), have been confirmed to belong to the HDL proteome. Similarly, the list of LDL-associated proteins has been enriched with 21 proteins involved in complement and coagulation cascades and the acute-phase response, which potentially double the protein species of LDL cargo. Moreover, differential expression analysis has shown protein signatures specific for patients with “hard” or “soft” plaques.

Dendrimer end-terminal motif-dependent evasion of human complement and complement activation through IgM hitchhiking

Complement is an enzymatic humoral pattern-recognition defence system of the body. Non-specific deposition of blood biomolecules on nanomedicines triggers complement activation through the alternative pathway, but complement-triggering mechanisms of nanomaterials with dimensions comparable to or smaller than many globular blood proteins are unknown. Here we study this using a library of <6 nm poly(amido amine) dendrimers bearing different end-terminal functional groups. Dendrimers are not sensed by C1q and mannan-binding lectin, and hence do not trigger complement activation through these pattern-recognition molecules. While, pyrrolidone- and carboxylic acid-terminated dendrimers fully evade complement response, and independent of factor H modulation, binding of amine-terminated dendrimers to a subset of natural IgM glycoforms triggers complement activation through lectin pathway-IgM axis. These findings contribute to mechanistic understanding of complement surveillance of dendrimeric materials, and provide opportunities for dendrimer-driven engineering of complement-safe nanomedicines and medical devices.

Understanding nanomaterials interactions with complement is important for a number of applications. Here, the authors study the interaction of sub 6 nm dendrimers with complement and show the small dendrimers escape complement activation but do interact with IgM to trigger lectin-pathway complement activation.

Serum biomarker discovery related to pathogenesis in acute coronary syndrome by proteomic approach

Acute coronary syndrome (ACS) results from inadequate supply of blood flow from the coronary arteries to the heart or ischemia. ACS has an extremely high morbidity and mortality. The levels of biomarkers currently used for detection of ACS also increase in response to myocardial necrosis and other diseases and are not elevated immediately after symptoms appear, thus limiting their diagnostic capacity. Therefore, we aimed to discover new ACS diagnostic biomarkers with high sensitivity and specificity that are specifically related to ACS pathogenesis. Sera from 50 patients with ACS and healthy controls (discovery cohort) each were analyzed using mass spectrometry (MS) to identify differentially expressed proteins, and protein candidates were evaluated as ACS biomarkers in 120 people in each group (validation cohort). α-1-acid glycoprotein 1 (AGP1), complement C5 (C5), leucine-rich α-2-glycoprotein (LRG), and vitronectin (VN) were identified as biomarkers whose levels increase and gelsolin (GSN) as a biomarker whose levels decrease in patients with ACS. We concluded that these biomarkers are associated with the pathogenesis of ACS and can predict the onset of ACS prior to the appearance of necrotic biomarkers.

Alternative C3 Complement System: Lipids and Atherosclerosis

Familial hypercholesterolemia (FH) is increasingly associated with inflammation, a phenotype that persists despite treatment with lipid lowering therapies. The alternative C3 complement system (C3), as a key inflammatory mediator, seems to be involved in the atherosclerotic process; however, the relationship between C3 and lipids during plaque progression remains unknown. The aim of the study was to investigate by a systems biology approach the role of C3 in relation to lipoprotein levels during atherosclerosis (AT) progression and to gain a better understanding on the effects of C3 products on the phenotype and function of human lipid-loaded vascular smooth muscle cells (VSMCs). By mass spectrometry and differential proteomics, we found the extracellular matrix (ECM) of human aortas to be enriched in active components of the C3 complement system, with a significantly different proteomic signature in AT segments. Thus, C3 products were more abundant in AT-ECM than in macroscopically normal segments. Furthermore, circulating C3 levels were significantly elevated in FH patients with subclinical coronary AT, evidenced by computed tomographic angiography. However, no correlation was identified between circulating C3 levels and the increase in plaque burden, indicating a local regulation of the C3 in AT arteries. In cell culture studies of human VSMCs, we evidenced the expression of C3, C3aR (anaphylatoxin receptor) and the integrin α_Mβ₂ receptor for C3b/iC3b (RT-PCR and Western blot). C3mRNA was up-regulated in lipid-loaded human VSMCs, and C3 protein significantly increased in cell culture supernatants, indicating that the C3 products in the AT-ECM have a local vessel-wall niche. Interestingly, C3a and iC3b (C3 active fragments) have functional effects on VSMCs, significantly reversing the inhibition of VSMC migration induced by aggregated LDL and stimulating cell spreading, organization of F-actin stress fibers and attachment during the adhesion of lipid-loaded human VSMCs. This study, by using a systems biology approach, identified molecular processes involving the C3 complement system in vascular remodeling and in the progression of advanced human atherosclerotic lesions.

Serum Complement C1q Activity Is Associated With Obstructive Coronary Artery Disease

Background: Complement C1q plays a dual role in the atherosclerosis. Previous studies showed inconsistent results about the association of serum C1q levels and coronary artery disease (CAD). Here, we explored the associations of serum C1q activity with CAD, coronary stenosis severity, cardiovascular biomarkers, and 1-year restenosis after coronary artery revascularization.

Methods: We enrolled 956 CAD patients and 677 controls to evaluate the associations of serum complement C1q activity to the presence and severity of obstructive CAD and non-obstructive CAD. Serum C1q activity and the concentrations of laboratory markers were measured in all subjects. All the data were analyzed using SPSS22.0 software.

Results: Serum C1q activity in Obstructive CAD and Non-Obstructive CAD groups was significantly higher than the control group (195.52 ± 48.31 kU/L and 195.42 ± 51.25 kU/L vs. 183.44 ± 31.75 kU/L, P < 0.05). Greater C1q activity was significantly correlated with higher total cholesterol (TC) and triglyceride (TG) levels. C1q activity was associated with an increased Odds Ratio (OR) of CAD (OR = 1.322, 95% CI 1.168–1.496, P < 0.05) and 1-year restenosis after revascularization (the highest OR = 3.544, 95% CI 1.089–12.702, P < 0.05). Complement C1q activity was not correlated with Gensini score in the Obstructive CAD group after adjustment for confounders. C1q activity has low value in predicting the incidence of CAD.

Conclusion: Serum complement C1q activity is associated with obstructive CAD.

Association between serum adipsin and plaque vulnerability determined by optical coherence tomography in patients with coronary artery disease

Background

Early identification of vulnerable plaques is important for patients with coronary artery disease (CAD) to reduce acute coronary events and improve their prognosis. We sought to examine the relationship between adipsin, an adipokine secreted from adipocytes, and plaque vulnerability in CAD patients.

Methods

A total of 103 plaques from 99 consecutive patients who underwent coronary angiography were assessed by optical coherence tomography. The serum level of adipsin was measured using enzyme-linked immunosorbent assay (ELISA). The accuracy of adipsin for detecting thin-cap fibroatheroma (TCFA) was determined by the area under the receiver operating characteristic curve (AUC).

Results

Of the 99 patients, 49 were classified into the low adipsin group and 50 into the high adipsin group according to the median level of serum adipsin (2.43 µg/mL). The plaques from the high adipsin group exhibited a greater lipid index (2,700.0 vs. 1,975.9° × mm, P=0.015) and an increased proportion of TCFAs (41.2% vs. 21.2%, P=0.028) compared with the low adipsin group. Serum adipsin was found to be negatively correlated with fibrous cap thickness (ρ=−0.322, P=0.002), while it was positively correlated with average lipid arc (ρ=0.253, P=0.015), maximum lipid arc (ρ=0.211, P=0.044), lipid core length (ρ=0.241, P=0.021), lipid index (ρ=0.335, P=0.001), and vulnerability score (ρ=0.254, P=0.014). Furthermore, adipsin had a significant association with TCFAs (OR: 1.290, 95% CI: 1.048–1.589, P=0.016) in the multivariate analysis, while having a moderate diagnostic accuracy for TCFAs (AUC: 0.710, 95% CI: 0.602–0.817, P<0.001).

Conclusions

Our findings suggest that serum adipsin is significantly and positively correlated with the incidence of TCFAs. The application of adipsin as a biomarker may offer improvement in the diagnosis of vulnerable plaques and clinical benefits for CAD patients.

Ficolin-2 serum levels predict the occurrence of acute coronary syndrome in patients with severe carotid artery stenosis

BACKGROUND AND PURPOSE

erosion of vulnerable atherosclerotic plaques may cause life-threatening thromboembolic complications. There is indeed an urgent need to recognize a clear-cut biomarker able to identify vulnerable plaques. Here, we focused on circulating proteins belonging to the lectin pathway (LP) of complement activation.

METHODS

we analyzed mannose-binding lectin (MBL), ficolin-1, -2 and -3 (LP initiators) levels by ELISA in sera from n = 240 of an already published cohort of patients undergoing endarterectomy for severe carotid stenosis and followed-up until 18 months after surgery. Immunofluorescence followed by confocal and polarized light microscopy was used to detect LP initiator intraplaque localization. Spearman's rank test was drawn to investigate correlation between serum LP levels and circulating inflammatory proteins or intraplaque components. Survival analyses were then performed to test the predictive role of LP on long-term adverse outcome.

RESULTS

ficolins, but not MBL, correlated positively with 1) high circulating levels of inflammatory markers, including MPO, MMP-8, MMP-9, ICAM-1, osteopontin, neutrophil elastase, and; 2) immune cell intraplaque recruitment. Immunofluorescence showed ficolins in calcified plaques and ficolin-2 in cholesterol-enriched plaque regions in association with macrophages. In the multivariate survival analysis, ficolin-2 serum levels predicted a major adverse cardiovascular event during the follow-up, independently of symptomatic status and inflammatory markers (hazard ratio 38.6 [95 % CI 3.9-385.2]).

CONCLUSIONS

ficolins support intraplaque immune cell recruitment and inflammatory processes ultimately leading to plaque vulnerability. Especially for ficolin-2 a strong predictive value toward adverse cardiovascular events was demonstrated. This evidence offers potentially new pharmacological target to dampen the inflammatory mechanisms leading to plaque vulnerability.

Adipsin deficiency does not impact atherosclerosis development in Ldlr-/- mice

Obesity is a potent risk factor for atherosclerotic morbidity and mortality. Cytokines secreted from adipose tissue, namely, adipokines, have been suggested to be actively involved in atherosclerosis. One of the most abundant adipokines, adipsin, is downregulated in obesity. It catalyzes the rate-limiting step of alternative complement activation, which is one of the three complement pathways potentially involved in inflammation in atherosclerosis. Interestingly, adipsin has been identified as a novel biomarker in human coronary artery disease. However, its role in the development of atherosclerosis remains unexplored. We crossed adipsin^-/- mice onto an Ldlr^-/- background [double-knockout (DKO) mice] and induced atherogenesis by high-fat and high-cholesterol feeding. Metabolic profiles were systemically characterized, and atherosclerotic plaques were measured at both aortic root and arch regions. Western blotting was conducted to assess adipsin level and complement activity. The DKO mice exhibited similar sizes of atherosclerotic lesions as Ldlr^-/- control mice at both the aortic root and arch regions. Accordingly, they displayed comparable metabolic parameters, including body weight, insulin sensitivity, and lipid profiles, along with compensated complement activity. Adipsin deficiency does not impact the development of atherosclerosis in Ldlr^-/- mice despite its crucial function in alternative complement activation. Therefore, it is unlikely to play an important role in mediating the risk of atherosclerotic complications in obesity.NEW & NOTEWORTHY Adipsin deficiency does not impact the development of atherosclerosis in Ldlr^-/- mice despite its crucial function in alternative complement activation. Therefore, it is unlikely to play an important role in mediating the risk of atherosclerotic complications in obesity.

Protein-Defined Subspecies of HDLs (High-Density Lipoproteins) and Differential Risk of Coronary Heart Disease in 4 Prospective Studies

OBJECTIVE

HDL (high-density lipoprotein) contains functional proteins that define single subspecies, each comprising 1% to 12% of the total HDL. We studied the differential association with coronary heart disease (CHD) of 15 such subspecies. Approach and Results: We measured plasma apoA1 (apolipoprotein A1) concentrations of 15 protein-defined HDL subspecies in 4 US-based prospective studies. Among participants without CVD at baseline, 932 developed CHD during 10 to 25 years. They were matched 1:1 to controls who did not experience CHD. In each cohort, hazard ratios for each subspecies were computed by conditional logistic regression and combined by meta-analysis. Higher levels of HDL subspecies containing alpha-2 macroglobulin, CoC3 (complement C3), HP (haptoglobin), or PLMG (plasminogen) were associated with higher relative risk compared with the HDL counterpart lacking the defining protein (hazard ratio range, 0.96-1.11 per 1 SD increase versus 0.73-0.81, respectively; P for heterogeneity <0.05). In contrast, HDL containing apoC1 or apoE were associated with lower relative risk compared with the counterpart (hazard ratio, 0.74; P=0.002 and 0.77, P=0.001, respectively).

CONCLUSIONS

Several subspecies of HDL defined by single proteins that are involved in thrombosis, inflammation, immunity, and lipid metabolism are found in small fractions of total HDL and are associated with higher relative risk of CHD compared with HDL that lacks the defining protein. In contrast, HDL containing apoC1 or apoE are robustly associated with lower risk. The balance between beneficial and harmful subspecies in a person's HDL sample may determine the risk of CHD pertaining to HDL and paths to treatment.

Complement Activation in Association with Markers of Neutrophil Extracellular Traps and Acute Myocardial Infarction in Stable Coronary Artery Disease

Complement activation and neutrophil extracellular traps (NETs) have both been suggested to drive atherosclerotic plaque progression. Although experimental studies suggest interplay between these two innate immunity components, the relevance in patients with coronary artery disease (CAD) is unclear. The aim of this study was to assess associations between complement activation and NETs in patients with stable CAD and examine the role of complement activation on clinical outcome. Blood samples from a cohort of patients with angiographically verified stable CAD (n = 1001) were analyzed by ELISA for the terminal complement complex (TCC) and by relative quantification for gene expression of the C5a receptor 1 (C5aR1) as markers of complement activation. As markers of NETs, dsDNA was analyzed by fluorescent nucleic acid stain and myeloperoxidase-DNA (MPO-DNA) by ELISA. Clinical outcome was defined as unstable angina, nonhemorrhagic stroke, acute myocardial infarction (MI), or death (n = 106, whereof 36 MI). Levels of TCC and C5aR1 were not significantly correlated to dsDNA (TCC: r = −0.045, p = 0.153; C5aR1: r = −0.060, p = 0.434) or MPO-DNA (TCC: r = 0.026, p = 0.414; C5aR1: r = 0.123, p = 0.107). When dividing TCC and C5aR1 levels into quartiles (Q), levels of MPO-DNA differed significantly across quartiles (TCC: p = 0.008, C5aR1: 0.049), while dsDNA did not (TCC: p = 0.181, C5aR1: p = 0.771). Patients with TCC levels in Q4 had significantly higher levels of MPO-DNA than Q1-3 (p = 0.019), and C5aR1 levels in Q3-4 had significantly higher levels of MPO-DNA than Q1-2 (p = 0.046). TCC levels did not differ between patients experiencing a clinical endpoint or not, but high levels were associated with increased risk of acute MI (OR. 1.97, 95% CI: 0.99-3.90, p = 0.053) during two-year follow up, also when adjusted for relevant covariates. In conclusion, TCC and C5aR1 were moderately associated with the NET marker MPO-DNA, and TCC levels were related to the risk of future MI in this cohort of patients with stable CAD.

Serum complement C1q level is associated with acute coronary syndrome

BACKGROUND AND OBJECTIVES

The complement system plays an important role in the development of acute coronary syndrome (ACS). Complement C1q is an important initial component of the classical complement pathway and closely related to many chronic inflammatory diseases, including atherosclerosis (AS). We aimed to determine whether there was association between serum complement C1q and the severity of coronary stenosis.

SUBJECTS AND METHODS

320 patients who underwent coronary arteriography (CAG) were stratified into non-ACS group (control group, n = 74), unstable angina group (UA group, n = 197) and acute myocardial infarction group (AMI group, n = 49) according to the severity of coronary stenosis and clinical manifestations. The severity of coronary stenosis was represented in Gensini score, and serum complement C1q level was compared using immunity transmission turbidity among three groups.

RESULTS

The level of complement C1q in AMI group was lower significantly than control group and UA group (P < 0.05), but there was no correlation between serum complement C1q and Gensini score (β=-0.086, P = 0.125). In nitrate-taking patients, serum complement C1q had a negative association with Gensini score (r=-0.275, P = 0.001), and in non-smokers, there was also a negative correlation (β=-0.159, P = 0.036). After calibrating smoking, drinking or statins, the serum complement C1q levels of control group, UA group and AMI group decreased in sequence (P <  0.05). Logistic regression analysis showed that the decreasing of serum complement C1q was an unfavorable factor for acute myocardial infarction (OR=0.984, 95 %CI=0.972∼0.997, P = 0.015) and for ACS (OR=0.984, 95 %CI=0.971∼0.984, P = 0.025) in drinking patients. Regrettably, ROC curve suggested that the accuracy in diagnosing coronary atherosclerotic heart disease by serum complement C1q was low (AUC=0.568, 95 %CI= 0.492-0.644, P = 0.076, sensitivity 73.6 %, specificity 58.1 %).

CONCLUSION

Serum complement C1q in ACS patients, in particular AMI patients, showed lower level. This finding suggests further decrease of complement C1q level in ACS patients may be a contributory factor to instability or rupture of atherosclerotic plaques. Combined with other clinical indicators, it can be helpful to predict the risk and severity of coronary stenosis.

Increased Complement Factor B and Bb Levels Are Associated with Mortality in Patients with Severe Aortic Stenosis

Inflammation is involved in initiation and progression of aortic stenosis (AS). However, the role of the complement system, a crucial component of innate immunity in AS, is unclear. We hypothesized that circulating levels of complement factor B (FB), an important component of the alternative pathway, are upregulated and could predict outcome in patients with severe symptomatic AS. Therefore, plasma levels of FB, Bb, and terminal complement complex were analyzed in three cohorts of patients with severe symptomatic AS and mild-to-moderate or severe asymptomatic AS (population 1, n = 123; population 2, n = 436; population 3, n = 61) and in healthy controls by enzyme immunoassays. Compared with controls, symptomatic AS patients had significantly elevated levels of FB (2.9- and 2.8-fold increase in population 1 and 2, respectively). FB levels in symptomatic and asymptomatic AS patients were comparable (population 2 and 3), and in asymptomatic patients FB correlated inversely with valve area. FB levels in population 1 and 2 correlated with terminal complement complex levels and measures of systemic inflammation (i.e., CRP), cardiac function (i.e., NT-proBNP), and cardiac necrosis (i.e., Troponin T). High FB levels were significantly associated with mortality also after adjusting for clinical and biochemical covariates (hazard ratio 1.37; p = 0.028, population 2). Plasma levels of the Bb fragment showed a similar pattern in relation to mortality. We concluded that elevated levels of FB and Bb are associated with adverse outcome in patients with symptomatic AS. Increased levels of FB in asymptomatic patients suggest the involvement of FB from the early phase of the disease.

Altered Expression of Complement Regulatory Proteins CD35, CD46, CD55, and CD59 on Leukocyte Subsets in Individuals Suffering From Coronary Artery Disease

Studies conducted in animal models have suggested that membrane complement regulatory proteins play an important role in the pathophysiology of coronary artery disease (CAD). In this study, a total of 100 individuals, with stable CAD and 100 healthy controls, both groups predominantly male, were recruited. We evaluated the plasma levels of complement regulatory proteins (Cregs) CD35, CD46, CD55, and CD59 and their surface expression on granulocytes, lymphocytes, and monocytes by flow cytometry. The mRNA expression of these Cregs in total leukocytes was determined by quantitative PCR. The soluble forms of Cregs, C3c, Mannose binding protein-associated serine protease 2 (MASP-2), Platelet activating factor-acetyl hydrolase (PAF-AH), and inflammatory cytokines were quantified by ELISA. High plasma levels of C3c, indicative of complement activation, in addition to significantly low levels of Cregs, were observed in CAD patients. A significantly lower expression of CD46 and CD55 on the surface of lymphocytes, monocytes, and granulocytes and higher surface expression of CD35 and CD59 on granulocytes (p < 0.0001) was seen in CAD patients as compared to healthy donors. The high expression of CD59 on granulocytes positively correlated with the severity of disease and may serve as a potential marker of disease progression in CAD.

Shotgun proteomic analysis reveals proteome alterations in HDL of patients with cholesteryl ester transfer protein deficiency

BACKGROUND

We previously reported that the patients with cholesteryl ester transfer protein (CETP) deficiency (CETP-D) show marked changes in the size and lipid compositions of high-density lipoprotein (HDL) and that they are not protected from atherosclerotic cardiovascular diseases, despite increased serum HDL-cholesterol (HDL-C) levels. HDL particles carry a variety of proteins, some of which are known to have antiatherogenic functions.

OBJECTIVE

This study aimed to investigate the protein composition of HDL particles in patients with CETP-D.

METHODS

Eight patients with complete deficiency of CETP and 8 normolipidemic healthy subjects were enrolled. We performed shotgun proteomic analysis to investigate the proteome of ultracentrifugally isolated HDL.

RESULTS

We identified 79 HDL-associated proteins involved in lipid metabolism, protease inhibition, complement regulation, and acute-phase response, including 5 potential newly identified HDL-associated proteins such as angiopoietin-like3 (ANGPTL3). Spectral counts of apolipoprotein (apo) E were increased in patients with CETP-D compared with controls (60.3 ± 6.9 vs 43.7 ± 2.5, P < .001), which is concordant with our previous report. Complement regulatory proteins such as C3, C4a, C4b, and C9 were also significantly enriched in HDL from patients with CETP-D. Furthermore, apoC-III and ANGPTL3, both of which are now known to associate with increased atherosclerotic cardiovascular diseases, were enriched in patients with CETP-D compared with normolipidemic subjects (35.9 ± 5.3 vs 27.1 ± 3.7, 2.3 ± 1.1 vs 0.4 ± 1.1, respectively; P < .01).

CONCLUSION

We have characterized HDL-associated proteins in patients with CETP-D. We identified a significant increase in the amount of apoE, apoC-III, ANGPTL3, and complement regulatory proteins. These proteomic changes might be partly responsible for the enhanced atherogenicity of patients with CETP-D.

TMT-Based Quantitative Proteomic Analysis Reveals Proteomic Changes Involved in Longevity

PURPOSE

Individual lifespans vary widely, and longevity is the main concern from ancient to modern times. This study is aimed to identify plasma proteins associated with longevity by proteomics technique.

EXPERIMENTAL DESIGN

Tandem mass tags (TMT)-based proteomics analysis is performed for the plasma of Bama longevity group and a control group to analyze the differentially expressed proteins (DEPs). A validation set is used to verify the results of TMT-based proteomics.

RESULTS

Between Bama natives and the control individuals, the authors identify 175 DEPs, which are mainly involved in complement and coagulation cascades, metabolism of glyco and lipid, and regulation of actin cytoskeleton. Consistent with the proteomic analysis, plasma levels of MMP2, CCL5, and PF4 are significantly lower in Bama participants than in controls, whereas IGFBP2 and C9 increase in Bama individuals, in the validation set. By ROC analysis, combinations of these five proteins result in a high AUC value (0.991, 95% CI, 0.929-1.000, p < 0.0001) to distinguish longevous participants from controls.

CONCLUSIONS AND CLINICAL RELEVANCE

The results highlight the roles of complement and coagulation cascades, metabolism of glyco and lipid, and inflammatory and immune response may play important roles in longevity. And the DEPs may serve as clinically useful biomarkers for healthy aging and predicting longevity.

Complement Complex C5b-9 Levels Are Associated with the Clinical Outcomes of Acute Ischemic Stroke and Carotid Plaque Stability

The terminal complement complex C5b-9 plays an important role in acute ischemic stroke (AIS) and carotid atherosclerosis. However, the associations between serum C5b-9, the severity and outcome of AIS, and the stability of carotid plaques have not been well investigated. In this clinical study, 70 patients with AIS and 70 healthy controls were enrolled. Serum C5b-9 levels at 72 h after stroke onset were measured by enzyme-linked immunosorbent assay (ELISA). Infarct size, the National Institutes of Health Stroke Scale (NIHSS), the 90-day modified Rankin Scale (mRS), and carotid plaque and stenosis were evaluated. Serum C5b-9 levels were significantly higher in AIS patients than in healthy controls (p < 0.001) and were correlated with infarction sizes (p = 0.045) and the NIHSS (P = 0.035). Furthermore, 90-day mRS analysis demonstrated that the patients with poor outcomes had higher serum C5b-9 levels than those with good outcomes (P < 0.001). Moreover, serum C5b-9 levels in AIS patients with unstable carotid plaques were much higher than in those with stable carotid plaques (P = 0.009). Multivariate logistic regression indicated that C5b-9 could be an independent risk factor for AIS (P < 0.001) and unstable carotid plaques (P = 0.015). Therefore, complement complex C5b-9 may be a potential biomarker in predicting the severity and outcome, as well as the stability of carotid plaques, in AIS patients.

Novel interactomics approach identifies ABCA1 as direct target of evodiamine, which increases macrophage cholesterol efflux

Evodiamine, a bioactive alkaloid from the fruits of the traditional Chinese medicine Evodia rutaecarpa (Juss.) Benth. (Fructus Evodiae, Wuzhuyu), recently gained attention as a dietary supplement for weight loss and optimization of lipid metabolism. In light of its use by patients and consumers, there is an urgent need to elucidate the molecular targets affected by this natural product. Using a novel interactomics approach, the Nematic Protein Organisation Technique (NPOT), we report the identification of ATP-binding cassette transporter A1 (ABCA1), a key membrane transporter contributing to cholesterol efflux (ChE), as a direct binding target of evodiamine. The binding of evodiamine to ABCA1 is confirmed by surface plasmon resonance (SPR) experiments. Examining the functional consequences of ABCA1 binding reveals that evodiamine treatment results in increased ABCA1 stability, elevated cellular ABCA1 protein levels, and ultimately increased ChE from THP-1-derived human macrophages. The protein levels of other relevant cholesterol transporters, ABCG1 and SR-B1, remain unaffected in the presence of evodiamine, and the ABCA1 mRNA level is also not altered.

Complement Component C3 Promotes Cerebral Ischemia/Reperfusion Injury Mediated by TLR2/NFκB Activation in Diabetic Mice

Complement component C3 (C3), a key factor in the complement system, is heavily involved in various inflammation-associated diseases. However, it remains obscure for its role in the pathogenesis of cerebral ischemia/reperfusion (I/R) injury in diabetes. A transient middle cerebral artery occlusion (tMCAO) model was used for cerebral I/R injury in streptozotocin-induced diabetic mice. Cerebral infarct volume and neurological function were measured at different times of reperfusion. Complement C3 was measured by ELISA and western blotting. It was observed that complement C3 expression was increased in cerebral I/R injury of diabetic mice, whereas complement C3 deficiency abrogated the activation and injury. Furthermore, activating complement C3 promotes TLR2/NFκB activation after I/R injury in diabetic mice, which is inhibited by of the silencing of TLR2. Taken together, our data demonstrate that complement C3 promotes cerebral I/R injury via the TLR2/NFκB pathway in diabetic mice, and regulating the complement C3/TLR2/NFκB pathway may be a novel target for therapeutic intervention in diabetic stroke.

Classical Pathway of Complement Activation: Longitudinal Associations of C1q and C1-INH With Cardiovascular Outcomes: The CODAM Study (Cohort on Diabetes and Atherosclerosis Maastricht)-Brief Report

OBJECTIVE

The classical complement pathway has been assigned both protective and pathological effects in cardiovascular disease (CVD), but human data are lacking. We determined the associations of the pattern recognition factor C1q and the regulator C1-INH (C1-inhibitor) with incident CVD, carotid intima-media thickness, endothelial dysfunction, and low-grade inflammation.

APPROACH AND RESULTS

Baseline concentrations of C1q and C1-INH were measured in the CODAM study (Cohort on Diabetes and Atherosclerosis Maastricht; n=574; 61% men; age, 60±7 years). The 7-year incidence of CVD in participants free of CVD at baseline was evaluated using logistic regression analyses (n=342; 73 cases). The lowest incidence of CVD was observed in the middle tertile of C1q (T_low compared with T_middle: odds ratio, 2.38 [95% confidence interval, 1.14-4.95]; T_high compared with T_middle: odds ratio, 1.96 [95% confidence interval, 0.94-4.07]). C1-INH was not associated with CVD. During the 7-year follow-up period, C1q and C1-INH were not, or inconsistently, associated with carotid intima-media thickness or with biomarker scores reflecting endothelial dysfunction and low-grade inflammation.

CONCLUSIONS

Our results suggest a nonlinear association between C1q and incident CVD. This supports the concept that early steps in classical pathway activation may have both protective and pathological effects on human CVD.

Post-transplant hypocomplementemia: A novel marker of cardiovascular risk in kidney transplant recipients?

BACKGROUND AND AIMS

Cardiovascular disease (CVD) is a leading cause of mortality after kidney transplantation (KT). The potential role of the complement system in the pathogenesis of post-transplant CVD remains unexplored.

METHODS

Serum complement (C3 and C4) levels were measured at baseline and post-transplant months 1 and 6 in 447 kT recipients. The study outcome was post-transplant atherothrombotic event (PAE), a composite of acute coronary syndrome, critical peripheral arterial disease, stroke and/or transient ischemic attack.

RESULTS

After a median follow-up of 4.2 years, 48 PAEs occurred in 43 patients (cumulative incidence: 9.6%; incidence rate: 2.6 events per 100 transplant-years). No differences were found in C3 and C4 levels at baseline or month 1 between patients with or without PAE. However, C3 levels at month 6 were significantly lower in patients developing PAE beyond that point (i.e., late PAE) (96.9 ± 22.3 vs. 109.6 ± 24.0 mg/dL; p = 0.013). The presence of C3 hypocomplementemia at month 6 was associated with a lower PAE-free survival (p = 0.002). After adjusting for conventional CVD risk factors and acute graft rejection, C3 hypocomplementemia at month 6 remained as an independent risk factor for late PAE in all the exploratory models (minimum hazard ratio: 3.24; p = 0.011). With respect to a model exclusively based on clinical variables, the inclusion of C3 levels at month 6 improved predictive capacity (areas under ROC curves: 0.788 and 0.812, respectively).

CONCLUSIONS

Post-transplant monitoring of serum C3 levels might be useful to identify KT recipients at increased risk of CVD.

Circulating complement component 4d (C4d) correlates with tumor volume, chemotherapeutic response and survival in patients with malignant pleural mesothelioma

Only limited information is available on the role of complement activation in malignant pleural mesothelioma (MPM). Thus, we investigated the circulating and tissue levels of the complement component 4d (C4d) in MPM. Plasma samples from 55 MPM patients, 21 healthy volunteers (HV) and 14 patients with non-malignant pleural diseases (NMPD) were measured by ELISA for C4d levels. Tissue specimens from 32 patients were analyzed by C4d immunohistochemistry. Tumor volumetry was measured in 20 patients. We found no C4d labeling on tumor cells, but on ectopic lymphoid structures within the tumor stroma. Plasma C4d levels did not significantly differ between MPM, HV or NMPD. Late-stage MPM patients had higher plasma C4d levels compared to early-stage (p = 0.079). High circulating C4d was associated with a higher tumor volume (p = 0.047). Plasma C4d levels following induction chemotherapy were significantly higher in patients with stable/progressive disease compared to those with partial/major response (p = 0.005). Strikingly, patients with low C4d levels at diagnosis had a significantly better overall survival, confirmed in a multivariate cox regression model (hazard ratio 0.263, p = 0.01). Our findings suggest that circulating plasma C4d is a promising new prognostic biomarker in patients with MPM and, moreover, helps to select patients for surgery following induction chemotherapy.