Elevated level of ADAMTS4 in plasma and peripheral monocytes from patients with acute coronary syndrome

Identification of Adamts4 as a novel adult cardiac injury biomarker with therapeutic implications in patients with cardiac injuries

Pathological cardiac remodeling as an aftermath of a severe cardiac injury can lead to ventricular dysfunction and subsequent heart failure. Adamts4, a metalloproteinase, and disintegrin with thrombospondin-like motif, involved in the turnover of certain extracellular matrix molecules and pathogenesis of osteoarthritis, also plays a role in cardiac remodeling although little is presently known about its expression and function in the heart. Here, we have investigated the dynamic expression pattern of Adamts4 during cardiogenesis and also in the adult heart. To our surprise, adult cardiac injury reactivated Adamts4 expression concomitant with fibrosis induction. To better understand the mechanism, cultured H9c2 cardiomyocyte cells were subjected to ROS injury and Hypoxia. Moreover, through combinatorial treatment with SB431542 (an inhibitor of Tgf-β1), and Adamts4 siRNA mediated gene knockdown, we were able to decipher a regulatory hierarchy to the signal cascade being at the heart of Tgf-β regulation. Besides the hallmark expression of Adamts4 and Tgf-β1, expression of other fibrosis-related markers like Collagen-III, alpha-SMA and Periostin were also assessed. Finally, increased levels of Adamts4 and alpha-SMA proteins in cardiac patients also resonated well with our animal and cell culture studies. Overall, in this study, we highlight, Adamts4 as a novel biomarker of adult cardiac injury.

Atherosclerosis Pathways are Activated in Pericoronary Adipose Tissue of Patients with Coronary Artery Disease

PURPOSE

Perivascular release of inflammatory mediators may accelerate coronary lesion formation and contribute to plaque instability. Accordingly, we compared gene expression in pericoronary adipose tissue (PCAT) in patients with advanced coronary artery disease (CAD) and non-CAD controls.

PATIENTS AND METHODS

PCAT samples were collected during coronary bypass grafting from CAD patients (n = 21) and controls undergoing valve replacement surgery, with CAD excluded by coronary angiography (n = 19). Gene expression was measured by GeneChip™ Human Transcriptome Array 2.0. Obtained list of 1348 transcripts (2.0%) that passed the filter criteria was further analyzed by Ingenuity Pathway Analysis software, identifying 735 unique differentially expressed genes (DEGs).

RESULTS

Among the CAD patients, 416 (30.9%) transcripts were upregulated, and 932 (69.1%) were downregulated, compared to controls. The top upregulated genes were involved in inflammation and atherosclerosis (chemokines, interleukin-6, selectin E and low-density lipoprotein cholesterol (LDL-C) receptor), whereas the downregulated genes were involved in cardiac ischaemia and remodelling, platelet function and mitochondrial function (miR-3671, miR-4524a, multimerin, biglycan, tissue factor pathway inhibitor (TFPI), glucuronidases, miR-548, collagen type I, III, IV). Among the top upstream regulators, we identified molecules that have proinflammatory and atherosclerotic features (High Mobility Group Box 2 (HMGB2), platelet-derived growth platelet (PDGF) and evolutionarily conserved signaling intermediate in Toll pathways (ESCIT)). The activated pathway related to DEGs consisted of molecules with well-established role in the pathogenesis of atherosclerosis (TFPI, plasminogen activator, plasminogen activator, urokinase receptor (PLAUR), thrombomodulin). Moreover, we showed that 22 of the altered genes form a pro-atherogenic network.

CONCLUSION

Altered gene expression in PCAT of CAD patients, with genes upregulation and activation of pathway involved in inflammation and atherosclerosis, may be involved in CAD development and progression.

ADAMTS proteases in cardiovascular physiology and disease

The a disintegrin-like and metalloproteinase with thrombospondin motif (ADAMTS) family comprises 19 proteases that regulate the structure and function of extracellular proteins in the extracellular matrix and blood. The best characterized cardiovascular role is that of ADAMTS-13 in blood. Moderately low ADAMTS-13 levels increase the risk of ischeamic stroke and very low levels (less than 10%) can cause thrombotic thrombocytopenic purpura (TTP). Recombinant ADAMTS-13 is currently in clinical trials for treatment of TTP. Recently, new cardiovascular roles for ADAMTS proteases have been discovered. Several ADAMTS family members are important in the development of blood vessels and the heart, especially the valves. A number of studies have also investigated the potential role of ADAMTS-1, -4 and -5 in cardiovascular disease. They cleave proteoglycans such as versican, which represent major structural components of the arteries. ADAMTS-7 and -8 are attracting considerable interest owing to their implication in atherosclerosis and pulmonary arterial hypertension, respectively. Mutations in the ADAMTS19 gene cause progressive heart valve disease and missense variants in ADAMTS6 are associated with cardiac conduction. In this review, we discuss in detail the evidence for these and other cardiovascular roles of ADAMTS family members, their proteolytic substrates and the potential molecular mechanisms involved.

The role of ADAMTS4 and ADAMTS9 in cardiovascular disease in premature ovarian insufficiency and idiopathic hypogonadotropic hypogonadism

PURPOSE

We aimed to determine the relation of a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS4), and a disintegrin and metalloproteinase with thrombospondin motifs-9 (ADAMTS9) with cardiovascular disease (CVD) risk, in ovarian dysfunction patients with premature ovarian insufficiency (POI), and idiopathic hypogonadotropic hypogonadism (IHH).

METHODS

43 IHH and 44 POI patients were enrolled to this case-control study. Serum hormonal parameters, lipid profiles, ADAMTS4 and ADAMTS9 levels were measured. Lipid accumulation product (LAP) index, visceral adiposity index (VAI), and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated. The patients with at least two out of the four following criteria were accepted to have increased CVD risk; waist-to-hip ratio (WHR) ≥ 0.8, waist circumference (WC) ≥ 79 cm, triglycerides (TG) ≥ 150 mg/dL, high-density lipoprotein cholesterol (HDL-C) < 50 mg/dL. Serum ADAMTS4 and ADAMTS9 levels were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

ADAMTS4 and ADAMTS9 levels were significantly higher in the IHH group than the POI group (p = 0.002, and p = 0.013, respectively). IHH group had significantly higher levels of insulin, HOMA-IR index, and LAP index (p = 0.006, p = 0.005, and p = 0.013, respectively). The mean age of patients in the IHH group (23.60 ± 5.64 years) was significantly lower than the POI group (31.05 ± 6.03 years), (p < 0.001). Odds ratios (OR) were 1.236 (95% CI 1.055-1.447) and 1.002 (95% CI 1.000-1.004) for LAP index and ADAMTS4, respectively, in the IHH group. These two parameters found to have high predictivity for CVD risk in the IHH group (p = 0.009 and p = 0.028, respectively).

CONCLUSION

The lower levels of ADAMTS4 in the POI group, when compared with the IHH patients pointed out that even limited hormone secretion and ovulation in the POI group, may have protective effect on cardiovascular system. The higher levels of ADAMTS4 and LAP index in the IHH group demonstrated the increased risk of these patients for CVD.

Elevated plasma levels of Mac-2 binding protein predict poor cardiovascular outcomes in patients with acute coronary syndrome

BACKGROUND

Mac-2 binding protein (M2BP) is an inflammatory glycoprotein associated with carotid atherosclerosis and all-cause mortality in patients with suspected coronary artery diseases. We aimed to explore the potential association of plasma M2BP levels with unstable plaque morphology and cardiovascular outcomes in patients with acute coronary syndrome (ACS).

PATIENTS AND METHODS

We compared plasma M2BP levels among three groups: 216 patients with ACS, 82 patients with stable angina pectoris, and 50 controls. Angiographic analyses of complex lesions were carried out in patients with ACS and they were followed up prospectively for 12 months for the occurrence of major adverse cardiovascular outcomes (MACEs).

RESULTS

Patients with ACS showed significantly higher plasma levels of M2BP than patients with stable angina pectoris (P<0.001) and controls (P<0.001). M2BP levels correlated positively with the presence (P<0.001) and extent (P=0.005) of complex lesions. During follow-up, 45 (20.8%) cases of MACEs occurred. Survival analysis indicated that high M2BP levels were associated with a poor prognosis (log-rank P=0.008). After Cox multivariate adjustment, plasma M2BP levels remained an independent predictor of MACEs either as a continuous variable (hazard ratio: 1.178, 95% confidence interval: 1.093-1.270, P<0.001) or as a categorical variable (hazard ratio: 2.783, 95% confidence interval: 1.433-5.404, P=0.002).

CONCLUSION

Plasma M2BP levels might be predictive of unstable plaque and were associated independently with poor cardiovascular outcomes in patients with ACS.

Loss of ADAMTS4 reduces high fat diet-induced atherosclerosis and enhances plaque stability in ApoE(-/-) mice

Atherosclerosis is a chronic inflammatory disease characterized by formation of lipid-rich plaques on the inner walls of arteries. ADAMTS4 (a disintegrin-like and metalloproteinase with thrombospondin motifs-4) is a secreted proteinase that regulates versican turnover in the arterial wall and atherosclerotic plaques. Recent reports indicated elevated ADAMTS4 level in human atherosclerotic plaques and in the plasma of acute coronary syndrome patients. Nevertheless, whether increased ADAMTS4 is a consequence of atherosclerosis or ADAMTS4 has a causal role in atherogenesis remains unknown. In this work, we investigated the role of ADAMTS4 in diet induced atherosclerosis using apolipoprotein E deficient (ApoE(-/-)) and Adamts4 knockout mice. We show that ADAMTS4 expression increases in plaques as atherosclerosis progresses in ApoE(-/-) mice. ApoE(-/-)Adamts4(-/-) double knockout mice presented a significant reduction in plaque burden at 18 weeks of age. Loss of ADAMTS4 lead to a more stable plaque phenotype with a significantly reduced plaque vulnerability index characterized by reduced lipid content and macrophages accompanied with a significant increase in smooth muscle cells, collagen deposition and fibrotic cap thickness. The reduced atherosclerosis is accompanied by an altered plasma inflammatory cytokine profile. These results demonstrate for the first time that ADAMTS4 contributes to diet induced atherosclerosis in ApoE(-/-) mice.

ADAMTS-4 activity in synovial fluid as a biomarker of inflammation and effusion

OBJECTIVE

To evaluate the potential of ADAMTS-4 (aggrecanase -1) activity in synovial fluid (SF) as a biomarker of knee injury and joint disease.

DESIGN

We have measured ADAMTS-4 activity in the synovial fluid of 170 orthopaedic patients with different degrees of joint pathology, using a commercial ADAMTS-4 fluorescence resonance energy transfer (FRET) substrate assay. Patients were classified at arthroscopy as (i) macroscopically normal, (ii) with an injury of the meniscus, anterior cruciate ligament or chondral/osteochondral defects or (iii) with osteoarthritis, and the influence of independent factors (age, patient group, effusion and synovial inflammation) on ADAMTS-4 activity levels was assessed.

RESULTS

In most patients (106/170) ADAMTS-4 activity was undetectable; ADAMTS-4 ranged from 0 to 2.8 ng/mL in synovial fluid from patients with an injury, 0-4.1 ng/mL in osteoarthritic patients and 4.0-12.3 ng/mL in patients with large effusions. Four independent variables each significantly influenced ADAMTS-4 activity in synovial fluid (all P < 0.001): age (concordance = 0.69), presence of osteoarthritis (OA) (concordance = 0.66), level of effusion (concordance = 0.78) and inflammation (concordance = 0.68). Not only did effusion influence the amount of ADAMTS-4 activity most strongly, but it also did this in an ordered manner (P < 0.001).

CONCLUSIONS

The main finding of this study is that ADAMTS-4 levels in synovial fluid are most strongly correlated with inflammation and severity of effusion in the knee. Further study is required to determine if it could provide a useful tool to aid clinical diagnoses, indicate treatment, to monitor progression of joint degeneration or OA or alternatively the success of treatment.

Integrative computational and experimental approaches to establish a post-myocardial infarction knowledge map

Vast research efforts have been devoted to providing clinical diagnostic markers of myocardial infarction (MI), leading to over one million abstracts associated with “MI” and “Cardiovascular Diseases” in PubMed. Accumulation of the research results imposed a challenge to integrate and interpret these results. To address this problem and better understand how the left ventricle (LV) remodels post-MI at both the molecular and cellular levels, we propose here an integrative framework that couples computational methods and experimental data. We selected an initial set of MI-related proteins from published human studies and constructed an MI-specific protein-protein-interaction network (MIPIN). Structural and functional analysis of the MIPIN showed that the post-MI LV exhibited increased representation of proteins involved in transcriptional activity, inflammatory response, and extracellular matrix (ECM) remodeling. Known plasma or serum expression changes of the MIPIN proteins in patients with MI were acquired by data mining of the PubMed and UniProt knowledgebase, and served as a training set to predict unlabeled MIPIN protein changes post-MI. The predictions were validated with published results in PubMed, suggesting prognosticative capability of the MIPIN. Further, we established the first knowledge map related to the post-MI response, providing a major step towards enhancing our understanding of molecular interactions specific to MI and linking the molecular interaction, cellular responses, and biological processes to quantify LV remodeling.

Heart attack, known medically as myocardial infarction, often occurs as a result of partial shortage of blood supply to a portion of the heart, leading to the death of heart muscle cells. Following myocardial infarction, complications might arise, including arrhythmia, myocardial rupture, left ventricular dysfunction, and heart failure. Although myocardial infarction can be quickly diagnosed using a various number of tests, including blood tests and electrocardiography, there have been no available prognostic tests to predict the long-term outcome in response to myocardial infarction. Here, we present a framework to analyze how the left ventricle responds to myocardial infarction by combining protein interactome and experimental results retrieved from published human studies. The framework organized current understanding of molecular interactions specific to myocardial infarction, cellular responses, and biological processes to quantify left ventricular remodeling process. Specifically, our knowledge map showed that transcriptional activity, inflammatory response, and extracellular matrix remodeling are the main functional themes post myocardial infarction. In addition, text analytics of relevant abstracts revealed differentiated protein expressions in plasma or serum expressions from patients with myocardial infarction. Using this data, we predicted expression levels of other proteins following myocardial infarction.

The anti-atherogenic cytokine interleukin-33 inhibits the expression of a disintegrin and metalloproteinase with thrombospondin motifs-1, -4 and -5 in human macrophages: Requirement of extracellular signal-regulated kinase, c-Jun N-terminal kinase and phosphoinositide 3-kinase signaling pathways

Atherosclerosis is an inflammatory disorder of the vasculature regulated by cytokines. Amongst the cytokines, IL-33 attenuates the development of atherosclerosis in mouse model systems via several mechanisms, including inhibition of macrophage foam cell formation and promotion of a Th1 to Th2 shift. Proteases produced by macrophages, such as matrix metalloproteinases and members of ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs) family, play potential roles in regulating atherosclerotic plaque stability. Despite such importance, the action of IL-33 on the expression of such proteases has not been analyzed. We have therefore investigated the effect of IL-33 on the expression of ADAMTS-1, -4 and -5 in human macrophages. Immunohistochemical analysis showed that these three proteases were expressed in human atherosclerotic lesions, particularly by macrophages and, to a lesser extent, by smooth muscle cells and endothelial cells. The expression of ADAMTS-1, -4 and -5 in human macrophages was specifically inhibited by IL-33. The action of IL-33 on the expression of these ADAMTS members was mediated through its receptor ST2. IL-33 activated ERK1/2, JNK1/2 and c-Jun, but not p38 MAPK or Akt, in human macrophages. RNA interference assays using a combination of adenoviral encoding small hairpin RNA and small interfering RNA showed a requirement of ERK1/2, JNK1/2, c-Jun, PI3Kγ and PI3Kδ, but not p38α, in the IL-33-inhibited expression of these ADAMTS isoforms. These studies provide novel insights into the expression of ADAMTS-1, -4 and -5 in human atherosclerotic lesions and the regulation of their expression in human macrophages by the key anti-atherogenic cytokine IL-33.

Assessment of the matrix degenerative effects of MMP-3, ADAMTS-4, and HTRA1, injected into a bovine intervertebral disc organ culture model

STUDY DESIGN

In vitro study to develop an intervertebral disc degeneration organ culture model, using coccygeal bovine intervertebral discs (IVDs) and injection of proteolytic enzymes MMP-3, ADAMTS-4, and HTRA1.

OBJECTIVE

This study aimed to develop an in vitro model of enzyme-mediated intervertebral disc degeneration to mimic the clinical outcome in humans for investigation of therapeutic treatment options.

SUMMARY OF BACKGROUND DATA

Bovine IVDs are comparable with human IVDs in terms of cell composition and biomechanical behavior. Researchers injected papain and trypsin into them to create an intervertebral disc degeneration model with a degenerated nucleus pulposus (NP) area. They achieved macroscopic cavities as well as a loss of glycosaminoglycans (GAGs). However, none of these enzymes are clinically relevant.

METHODS

Bovine IVDs were harvested maintaining the endplates. Active forms of MMP-3, ADAMTS-4, and HTRA1 were injected at a dose of 10 μg/mL each. Phosphate-buffered saline was injected as a control. Discs were cultured for 8 days and loaded diurnally (days 1-4 with ≈0.4 MPa for 16 hr) and left under free swelling condition from days 4 to 8 to avoid expected artifacts because of dehydration of the NP. Outcome parameters included disc height, metabolic cell activity, DNA content, GAG content, total collagen content, relative gene expression, and histological investigation.

RESULTS

The mean metabolic cell activity was significantly lower in the NP area of discs injected with ADAMTS-4 than the day 0 control discs. Disc height was decreased after injection with HTRA1 and was significantly correlated with changes in GAG/DNA of the NP tissue. Total collagen content tended to be lower in groups injected with ADAMTS4 and MMP-3.

CONCLUSION

MMP-3, ADAMTS-4, and HTRA1 provoked neither visible matrix degradation nor major shifts in gene expression. However, cell activity was significantly reduced and HTRA1 induced loss of disc height that positively correlated with changes in GAG/DNA content. The use of higher doses of these enzymes or a combination thereof may, therefore, be necessary to induce disc degeneration.

Regulation of ADAMTS-1, -4 and -5 expression in human macrophages: differential regulation by key cytokines implicated in atherosclerosis and novel synergism between TL1A and IL-17

•

Atherosclerosis is an inflammatory disorder regulated by cytokines.

•

ADAMTS proteases have been suggested to play an important role in this disease.

•

The action of key cytokines on the expression of ADAMTS proteases in macrophages is poorly understood.

•

The effect of IFN-γ, TGF-β, TL1A and IL-17A on the expression of ADAMTS-1, -4 and -5 was studied.

•

Novel differential actions and synergistic interactions were identified.

Atherosclerosis is an inflammatory disease of the vasculature regulated by cytokines. Macrophages play a crucial role at all stages of this disease, including regulation of foam cell formation, the inflammatory response and stability of atherosclerotic plaques. For example, matrix metalloproteinases produced by macrophages play an important role in modulating plaque stability. More recently, the ADAMTS proteases, which are known to play a key role in the control of cartilage degradation during arthritis, have been found to be expressed in atherosclerotic lesions and suggested to have potentially important functions in the control of plaque stability. Unfortunately, the action of cytokines on the expression of ADAMTS family in macrophages is poorly understood. We have investigated the effect of classical cytokines (IFN-γ and TGF-β) and those that have been recently identified (TL1A and IL-17) on the expression of ADAMTS-1, -4 and -5 in human macrophages. The expression of all three ADAMTS members was induced during differentiation of monocytes into macrophages. TGF-β had a differential action with induction of ADAMTS-1 and -5 expression and attenuation in the levels of ADAMTS-4. In contrast, IFN-γ suppressed the expression of ADAMTS-1 without having an effect on ADAMTS-4 and -5. Although TL-1A or IL-17A alone had little effect on the expression of all the members, they induced their expression synergistically when present together. These studies provide new insight into the regulation of key ADAMTS family members in human macrophages by major cytokines in relation to atherosclerosis.

Monocyte gene expression and coronary artery disease

PURPOSE OF REVIEW

Despite current therapy, coronary artery disease (CAD) remains the major cause of morbidity and mortality worldwide. CAD is the consequence of a complex array of deranged metabolic processes including the immune system. In this context, monocytes and macrophages are indisputable players. Thus, monocyte gene expression analysis could be a powerful tool to provide new insights in the pathophysiology of CAD and improve identification of individuals at risk. We discuss current literature assessing monocyte gene expression and its association with CAD.

RECENT FINDINGS

Monocyte surface markers CD14 ⁺⁺and CD16⁺ have been established as biomarkers for increased cardiovascular disease risk in a large number of studies. More in-depth gene expression analysis identified several interesting genes, such as ABCA1, CD36 and MSR1 with an increased expression in circulating monocytes from patients with CAD. The results for CD36 were replicated in one other study. For ABCA1 and MSR1 conflicting data are published.

SUMMARY

Recent findings indicate that genetic differences exist in circulating monocytes of patients suffering from CAD, giving us more insights into the underlying mechanisms. However, larger studies are required to prove that monocytes' expression signature could serve as a marker for diagnostic purposes in the future.

Pre- and early in-hospital procedures in patients with acute coronary syndromes: first results of the "German chest pain unit registry"

BACKGROUND

In an attempt to improve the treatment of patients with acute coronary syndromes (ACS), a network of certified chest pain units (CPUs) has been recently established in Germany.

METHODS

Data from patients admitted between December 2008 and September 2011 for ACS in 40 certified CPUs participating in the registry were prospectively collected.

RESULTS

A total of 5,457 patients was admitted for ACS; 798 patients (14.6 %) were diagnosed with an ST-elevation myocardial infarction (STEMI), 2,244 (41.1 %) with a non-ST-elevation myocardial infarction (NSTEMI), and 2,415 (44.3 %) with unstable angina. The mean time to first medical contact was 2:08 h for STEMI patients. A pre-hospital ECG was available in 23.8 % of all ACS patients. Importantly, evidence of ST-segment elevation was present in 79.7 % of the STEMI patients already in this pre-hospital ECG. As many as 76.6 % of the patients, independently of their symptoms and final diagnosis, received an ECG within 10 min of reaching the CPU. 98.2 % of STEMI patients underwent invasive diagnostics, with an in-hospital delay as little as 31 (11-75) min.

CONCLUSION

The establishment of a nation-wide network of certified CPUs optimizes the medical treatment of patients with ACS while providing an ideal infrastructure to evaluate and improve, both on a nation-wide and a single center scale, the adherence to guidelines. The median delay between symptom onset and first medical contact remains high. Although performed relatively rarely, a pre-hospital ECG facilitates earlier diagnosis of a STEMI in a large majority of patients. The introduction of CPUs minimizes in-hospital delays and exploits the benefit of invasive diagnostics and treatment.