C-reactive protein induces apoptosis in human coronary vascular smooth muscle cells

C-Reactive Protein: An Important Inflammatory Marker of Coronary Atherosclerotic Disease

Cardiovascular disease (CVD) is the most common cause of death worldwide, with coronary atherosclerotic heart disease (CHD) accounting for the majority of events. Evidence demonstrates that inflammation plays a vital role in the development of CHD. The association between C-reactive protein (CRP), a representative inflammatory biomarker, and atherosclerosis (AS), CHD, and inflammation has attracted attention. Therefore, we conducted an extensive search on PubMed using the aforementioned terms as search criteria and identified a total of 1246 articles published from January 2000 to April 2024. Both review and research-based articles consistently indicate CRP as a risk enhancer for CVD, contributing to the refinement of risk stratification and early identification of apparently healthy at-risk populations. Additionally, CRP reflects disease progression and predicts the prognosis of recurrent cardiovascular events. Anti-inflammatory therapeutic strategies targeting CRP also provide new treatment options for patients. This review focuses on the link between CRP and CHD, highlighting how CRP is involved in the pathological progression of AS and its potential value for clinical applications.

Peritoneal Inflammation in PD-Related Peritonitis Induces Systemic Eryptosis: In Vitro and In Vivo Assessments

Erythrocytes (RBCs) have a highly specialized and organized membrane structure and undergo programmed cell death, known as eryptosis. Our preliminary data show a significant increase in the eryptosis during peritoneal dialysis (PD)-associated peritonitis. The objectives of the present study were assessment of the incrementation of eryptosis in PD patients with peritonitis, evaluation of the relationship between systemic eryptosis in peritonitis and specific peritonitis biomarkers in PD effluent (PDE), and confirmation of the induction of eryptosis by peritonitis in a vitro setting. We enrolled 22 PD patients with peritonitis and 17 healthy subjects (control group, CTR). For the in vivo study, eryptosis was measured in freshly isolated RBCs. For the in vitro study, healthy RBCs were exposed to the plasma of 22 PD patients with peritonitis and the plasma of the CTR group for 2, 4, and 24 h. Eryptosis was evaluated by flow cytometric analyses in vivo and in vitro. PDE samples were collected for biomarkers analysis.The percentage of eryptotic RBCs was significantly higher in PD patients with peritonitis than in CTR (PD patients with peritonitis: 7.7; IQR 4.3-14.2, versus CTR: 0.8; IQR 0.7-1.3; p < 0.001). We confirmed these in vivo results by in vitro experiments: healthy RBCs incubated with plasma from PD patients with peritonitis demonstrated a significant increase in eryptosis compared to healthy RBCs exposed to plasma from the control group at all times. Furthermore, significant positive correlations were observed between eryptosis level and all analyzed peritoneal biomarkers of peritonitis. We investigated a potential connection between systemic eryptosis and peritoneal biomarkers of peritonitis. Up-regulation of inflammatory markers could explain the increased rate of systemic eryptosis during PD-related peritonitis.

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.

An integrative review of nonobvious puzzles of cellular and molecular cardiooncology

Oncologic patients are subjected to four major treatment types: surgery, radiotherapy, chemotherapy, and immunotherapy. All nonsurgical forms of cancer management are known to potentially violate the structural and functional integrity of the cardiovascular system. The prevalence and severity of cardiotoxicity and vascular abnormalities led to the emergence of a clinical subdiscipline, called cardiooncology. This relatively new, but rapidly expanding area of knowledge, primarily focuses on clinical observations linking the adverse effects of cancer therapy with deteriorated quality of life of cancer survivors and their increased morbidity and mortality. Cellular and molecular determinants of these relations are far less understood, mainly because of several unsolved paths and contradicting findings in the literature. In this article, we provide a comprehensive view of the cellular and molecular etiology of cardiooncology. We pay particular attention to various intracellular processes that arise in cardiomyocytes, vascular endothelial cells, and smooth muscle cells treated in experimentally-controlled conditions in vitro and in vivo with ionizing radiation and drugs representing diverse modes of anti-cancer activity.

Eryptosis in Peritoneal Dialysis-Related Peritonitis: The Potential Role of Inflammation in Mediating the Increase in Eryptosis in PD

Background: Peritonitis and exit site infections are the main complications of patients treated with peritoneal dialysis (PD). Erythrocytes (red blood cells—RBCs) are very sensitive cells, and they are characterized by eryptosis (programmed cell death). The purpose of this research was to assess eryptosis in PD patients with PD-related peritonitis and its connection to inflammatory markers in vivo and in vitro. Material and Methods: In this study, we included 65 PD patients: 34 PD patients without systemic inflammation nor PD-related peritonitis in the previous 3 months, and 31 PD patients with an acute episode of PD-related peritonitis. We measured C-reactive protein (CRP) and cytokine (IL-1β, IL-6, and IL-18) levels as systemic inflammatory markers. Eryptosis was evaluated by flow cytometric analyses in freshly isolated RBCs. The induction of eryptosis due to in vitro exposure to IL-1β, IL-6, and IL-18 was verified. Results: Eryptosis was significantly higher in PD patients with peritonitis (9.6%; IQR 4.2−16.7), compared to the those in the other group (2.7%; IQR 1.6−3.9) (p < 0.0001). Significant positive correlations were noticed between eryptosis and CRP, IL-1β, and IL-6. RBCs, incubated with greater concentrations of all cytokines in vitro, resulted in significantly higher occurrences of eryptosis in comparison with those incubated with lower concentration and with untreated cell (p < 0.05), and for those with extensive exposure (p < 0.05). Conclusion: In conclusion, we investigated a potential relationship between systemic eryptosis and the in vivo and in vitro inflammatory damage of the peritoneal membrane during peritonitis. Thus, the presented results revealed that upregulated inflammatory markers and immune system dysregulation could be the cause of high levels of systemic eryptosis during PD-related peritonitis.

Impact of acute inflammation on Band 3 protein anion exchange capability in human erythrocytes

Objective: The impact of acute inflammation, revealed by C-reactive protein (CRP) plasma levels, has been studied on the erythrocytes anion exchanger Band 3 protein.Methods: Anion exchange capability through Band 3 protein, lipid peroxidation, -SH membrane groups and intracellular GSH levels have been measured on erythrocytes from patients with CRP >8 mg/L.Results: Under acute inflammation, a significant increase in anion exchange capability, increased lipid peroxidation, decreased-SH groups and GSH content were observed. Serum CRP levels recovery (after one week) was associated to -SH groups and GSH recovery, but not to anion exchange capability restoration. After 2 months, a total recovery of all parameters was observed.Conclusion: Band 3 protein anion exchange capability is affected by acute inflammation; the accelerated rate of anion exchange may be mainly due to lipid peroxidation, rather than to -SH groups oxidation; erythrocytes renewal could be needed to have a total recover of their function.

In Vitro Induction of Eryptosis by Uremic Toxins and Inflammation Mediators in Healthy Red Blood Cells

Eryptosis is the stress-induced RBC (red blood cell) death mechanism. It is known that eryptosis is largely influenced by plasma and blood composition, and that it is accelerated in patients affected by chronic kidney disease (CKD). The aim of this study is to evaluate the eryptosis rate in healthy RBCs treated with different concentration of IL-6, IL-1β, urea and p-cresol, comparable to plasmatic level of CKD patients, at different time points. We exposed healthy RBCs to increasing concentrations of IL-6, IL-1β, urea and p-cresol. Morphological markers of eryptosis (cell membrane scrambling, cell shrinkage and PS exposure at RBC surface) were evaluated by flow cytometric analyses. The cytotoxic effect of cytokines and uremic toxins were analyzed in vitro on healthy RBCs at 4, 8 and 24 h. Morphology of treated RBCs was dramatically deranged, and the average cell volume was significantly higher in RBCs exposed to higher concentration of all molecules (all, p < 0.001). Furthermore, healthy RBCs incubated with each molecules demonstrated a significant increase in eryptosis. Cytofluorimetric analysis of eryptosis highlighted significantly higher cell death rate in RBCs incubated with a higher concentration of both cytokines compared with RBCs incubated with a lower concentration (all, p < 0.05). In conclusion, our data show that cytokines and uremic toxins have a harmful effect on RBCs viability and trigger eryptosis. Further studies are necessary to validate these results in vivo and to associate abnormal eryptosis with cytokine levels in CKD patients. The eryptosis pathway could, moreover, become a new promising target for anemia management in CKD patients.

Investigation of the Associations of Novel Inflammatory Biomarkers-Systemic Inflammatory Index (SII) and Systemic Inflammatory Response Index (SIRI)-With the Severity of Coronary Artery Disease and Acute Coronary Syndrome Occurrence

Atherosclerosis, the underlying cause of coronary artery disease (CAD), has a significant inflammatory component. White blood cell count is an affordable and accessible way to assess the systemic immune response, as it comprises many subgroups with distinct and complex functions. Considering their multidirectional effect on atherosclerosis, new biomarkers integrating various leukocyte subgroups, the Systemic Inflammatory Index (SII) and the Systemic Inflammatory Response Index (SIRI), were recently devised to describe the balance between inflammation and immune reaction. This research aimed to evaluate the relationship of the intensity of inflammation measured by these biomarkers with the severity of CAD assessed with coronary angiography and with the diagnosis of acute coronary syndrome (ACS) or stable CAD in 699 patients. SIRI, but not SII, was associated with the diagnosis, having the highest values for patients with ACS (STEMI), significantly higher than in patients with stable CAD (p < 0.01). The highest SII and SIRI values were observed in patients with three-vessel CAD. SII and SIRI require further in-depth and well-designed research to evaluate their potential in a clinical setting.

Neutrophil-to-Lymphocyte Ratio Is Not Associated with Severity of Coronary Artery Disease and Is Not Correlated with Vitamin D Level in Patients with a History of an Acute Coronary Syndrome

Coronary artery disease (CAD), the leading cause of death worldwide, has an underlying cause in atherosclerosis. The activity of this inflammatory process can be measured with neutrophil-to-lymphocyte ratio (NLR). The anti-inflammatory and anti-atherogenic properties of vitamin D affect many mechanisms involved in CAD. In this study, we investigated the association between NLR, vitamin D concentration, and severity of CAD in a group of patients with a history of myocardial infarction (MI). NLR was higher in patients with acute coronary syndrome (ACS) in comparison to those with stable CAD (median: 2.8, range: 0.96−24.3 vs. median: 2.3, range: 0.03−31.6; p < 0.05). No associations between NLR and severity of CAD (p = 0.14) in the cohort and in the subgroups with stable CAD (p = 0.40) and ACS (p = 0.34) were observed. We found no correlation between vitamin D level and NLR neither in the whole study group (p = 0.29) nor in subgroups of patients with stable CAD (p = 0.84) and ACS (p = 0.30). NLR could be used as prognostic biomarker of consecutive MI in patients with CAD and a history of MI.

Radiation-induced C-reactive protein triggers apoptosis of vascular smooth muscle cells through ROS interfering with the STAT3/Ref-1 complex

Damage to normal tissue can occur over a long period after cancer radiotherapy. Free radical by radiation can initiate or accelerate chronic inflammation, which can lead to atherosclerosis. However, the underlying mechanisms remain unclear. Vascular smooth muscle cells (VSMCs) proliferate in response to JAK/STAT3 signalling. C-reactive protein (CRP) can induce VSMCs apoptosis via triggering NADPH oxidase (NOX). Apoptotic VSMCs promote instability and inflammation of atherosclerotic lesions. Herein, we identified a VSMCs that switched from proliferation to apoptosis through was enhanced by radiation-induced CRP. NOX inhibition using lentiviral sh-p22^phox prevented apoptosis upon radiation-induced CRP. CRP overexpression reduced the amount of STAT3/Ref-1 complex, decreased JAK/STAT phosphorylation and formed a new complex of Ref-1/CRP in VSMC. Apoptosis of VSMCs was further increased by CRP co-overexpressed with Ref-1. Functional inhibition of NOX or p53 also prevented apoptotic activity of the CRP-Ref-1 complex. Immunofluorescence showed co-localization of CRP, Ref-1 and p53 with α-actin-positive VSMC in human atherosclerotic plaques. In conclusion, radiation-induced CRP increased the VSMCs apoptosis through Ref-1, which dissociated the STAT3/Ref-1 complex, interfered with JAK/STAT3 activity, and interacted with CRP-Ref-1, thus resulting in transcription-independent cell death via p53. Targeting CRP as a vascular side effect of radiotherapy could be exploited to improve curability.

C-reactive protein as an effector molecule in Covid-19 pathogenesis

The current pandemic caused by SARS-CoV-2 virus infection is known as Covid-19 (coronavirus disease 2019). This disease can be asymptomatic or can affect multiple organ systems. Damage induced by the virus is related to dysfunctional activity of the immune system, but the activity of molecules such as C-reactive protein (CRP) as a factor capable of inducing an inflammatory status that may be involved in the severe evolution of the disease, has not been extensively evaluated. A systematic review was performed using the NCBI-PubMed database to find articles related to Covid-19 immunity, inflammatory response, and CRP published from December 2019 to December 2020. High levels of CRP were found in patients with severe evolution of Covid-19 in which several organ systems were affected and in patients who died. CRP activates complement, induces the production of pro-inflammatory cytokines and induces apoptosis which, together with the inflammatory status during the disease, can lead to a severe outcome. Several drugs can decrease the level or block the effect of CRP and might be useful in the treatment of Covid-19. From this review it is reasonable to conclude that CRP is a factor that can contribute to severe evolution of Covid-19 and that the use of drugs able to lower CRP levels or block its activity should be evaluated in randomized controlled clinical trials.

C-Reactive Protein Controls IL-23 Production by Human Monocytes

C-reactive protein (CRP) is an acute-phase protein in humans that is produced in high quantities by the liver upon infection and under inflammatory conditions. Although CRP is commonly used as a marker of inflammation, CRP can also directly contribute to inflammation by eliciting pro-inflammatory cytokine production by immune cells. Since CRP is highly elevated in serum under inflammatory conditions, we have studied the CRP-induced cytokine profile of human monocytes, one of the main innate immune cell populations in blood. We identified that CRP is relatively unique in its capacity to induce production of the pro-inflammatory cytokine IL-23, which was in stark contrast to a wide panel of pattern recognition receptor (PRR) ligands. We show that CRP-induced IL-23 production was mediated at the level of gene transcription, since CRP particularly promoted gene transcription of IL23A (encoding IL-23p19) instead of IL12A (encoding IL-12p35), while PRR ligands induce the opposite response. Interestingly, when CRP stimulation was combined with PRR ligand stimulation, as for example, occurs in the context of sepsis, IL-23 production by monocytes was strongly reduced. Combined, these data identify CRP as a unique individual ligand to induce IL-23 production by monocytes, which may contribute to shaping systemic immune responses under inflammatory conditions.

Blocking FcγRIIB in Smooth Muscle Cells Reduces Hypertension

[Figure: see text].

Mechanism of Physical Exercise on Lowering Levels of C-Reactive Protein (CRP) in Overweight and Obese

Cases of overweight and obesity in the world increased continuously. In 2016, obesity increased by 3% in men and 6% in women compared to 1975. Overweight cases also increased by 20% in men and 23% in women compared to 1975. Overweight and obesity have been linked to an increase in adipose tissue in the body. Increased adipose tissue associated with inflammation, which one of its characteristics is an increase levels of C - Reactive Protein (CRP). This article aim is to describe the mechanism of physical exercise to diminish CRP level in overweight and obesity. Adipose tissue produces and releases various pro-inflammatory and anti-inflammatory factors such as leptin, adiponectin, resistin, TNF-α, IL-6, MCP-1 and CRP. One of the prevention and treatment of inflammatory for overweight and obesity cases is to do physical exercise. In cases of overweight and obesity, the physical exercise aims to increase energy expenditure. Physical exercise decreases the volume and amount of adipose and pre-adipose tissue as well as the number of endothelial cells and macrophages in adipose that contain pro-inflammation such as IL-1, TNF-α, CRP, serum amyloid protein (SAA), and cytokines. Physical exercise rises anti-inflammatory properties such as IL-10, IL-1ra which play a role in inhibiting the transduction of IL-1β signals and inhibiting TNF-α synthesis. Physical exercise also amplifies antioxidant enzymes such as SOD and GPX. The antioxidants play a role in fighting free radicals to reduce inflammation.

Pathogenic role of human C-reactive protein in diabetic retinopathy

PURPOSE

Elevated blood levels of C-reactive protein (CRP) are associated with both type 1 and type 2 diabetes and diabetic complications, such as diabetic retinopathy (DR). However, its pathogenic role in DR remains unknown. The present study aims to investigate the potential role of CRP in DR pathogenesis and explore its underlying mechanism.

MATERIALS AND METHODS

Human CRP transgenic (hCRP-Tg) rats were employed for streptozotocin (STZ)-induced diabetic and oxygen-induced retinopathy (OIR) models. The retina function was monitored by electroretinography (ERG) and retinal thickness was measured by optical coherence tomography (OCT). TUNEL and cell death ELISA were performed to measure the apoptosis. Oxidative stress was detected by the measurement of reactive oxygen species (ROS) in cells and 3-Nitrotyrosine staining in tissue sections.

RESULTS

In non-diabetic condition, hCRP-Tg with elevated hCRP levels in the retinas demonstrated declined ERG responses and decreased retinal thickness. In STZ-induced diabetic condition, overexpression of hCRP deteriorated retinal neurodegeneration as shown by ERG and apoptosis assays. hCRP also exacerbated retinal leukostasis and acellular capillary formation induced by diabetes. In the OIR model, overexpression of hCRP exacerbated retinal neovascularization (NV). In retinal cell lines, hCRP treatment induced cell death and over-production of ROS. Furthermore, hCRP-induced overexpression of pro-inflammatory, pro-oxidative, and pro-angiogenic factors was associated with up-regulation of CD32 and the NF-κB signaling in the retinas.

CONCLUSIONS

Elevated hCRP levels play a pathogenic role in DR. Targeting the hCRP-CD32-NF-κB pathway may represent a novel therapeutic strategy for DR.

Religiosity/Spirituality and Physiological Markers of Health

The long-standing interest in the effects of religiosity and spirituality (R/S) on health outcomes has given rise to a large and diverse literature. We conducted a meta-analysis on research involving R/S and physiological markers of health to elucidate both the scope and mechanism(s) of this phenomenon. A combined analysis found a significant, but small, beneficial effect. Subgroup analyses found that some measures of both extrinsic and intrinsic religiosity were significantly associated with health. Several outcome measures, including blood pressure, C-reactive protein, and cardiovascular health markers, were significantly associated with R/S. Our findings suggest that R/S benefits health, perhaps through minimizing the disruptive effects of stress/depression on inflammation. We hope that researchers can use these results to guide efforts aimed at elucidating the true mechanism(s) linking religious/spiritual beliefs and physical health.

C-reactive protein promotes inflammation through TLR4/NF-κB/TGF-β pathway in HL-1 cells

Atrial fibrillation (AF) is the most common type of heart arrhythmia. Currently, the pathogenesis of AF is not fully understood yet. A growing body of evidence highlighted the strong association between inflammation and the pathogenesis of AF. C-reactive protein (CRP) is an inflammation marker with increased expression in AF. Therefore, the aim of this study was to determine if CRP promotes inflammation, which may sequentially mediate the onset of AF and the concurrent atrial fibrosis, through TLR4/NF-κB/TGF-β pathway. HL-1 cells were treated with either 25 or 50 μg/ml recombinant human CRP. TGF-β1 and NF-κB inhibitors were given either solely or together to the 50 μg/ml CRP-treated cells. Cell proliferation, apoptosis, the expression of apoptotic factors and TLR4, IL-6, TGF-β1, Smad2, and the phosphorylation of Smad2 were determined. Data showed that CRP induced dose-dependent inhibition on cell proliferation and promoted cell apoptosis, which was induced through both intrinsic and extrinsic pathways. Such effects were reversed by inhibiting TGF-β1 and/or NF-κB. Inhibition of TGF-β1 and/or NF-κB also reduced the expression of TLR4 and IL-6. Inhibition of NF-κB alone weakened the expression of TGF-β1 and phosphorylation of Smad2. Our study demonstrated that CRP is not only a marker, but also an important mediator in the induction of inflammation and likely the pathogenesis of AF. We for the first time reported CRP-induced activation and cross-talk between TLR4 and NF-κB/TGF-β1 signaling pathway in a cardiomyocyte model. Reducing CRP and targeting TLR4/NF-κB/TGF-β1 pathway may provide new insights in the therapeutic interventions to inflammation-induced AF.

Association of plasma macrophage colony-stimulating factor with cardiovascular morbidity and all-cause mortality in chronic hemodialysis patients

Background

Cardiovascular disease (CVD) events are the main cause of death in long-term hemodialysis (HD) patients. Macrophage colony- stimulating factor (M-CSF) is actively involved in the formation of atherosclerosis and causes plaque instability, thrombosis and the development of acute coronary syndromes. However, little information is available on the role of M-CSF in HD patients. We aimed to investigate the association between plasma M-CSF levels and CVD events as well as all-cause mortality in patients undergoing long-term HD.

Methods

Fifty two HD patients and 8 healthy controls were recruited in this study. HD patients were followed up from September 2014 to May 2017. The primary end point was CVD event, the secondary outcome was death from any cause. Patients were divided into two groups with low and high M-CSF levels based on the optimal cut-off value determined by the ROC curve. Cox regression analyses were used to assess the predictive value of plasma M-CSF for CVD events and all-cause mortality in HD patients. We tested the levels of plasma M-CSF and other inflammatory cytokines in surviving HD patients using ELISA or CBA kit.

Results

The average plasma level of M-CSF in 52 patients was approximately twice that of healthy controls (992.4 vs. 427.2 pg/mL; p <  0.05). During 32 months of follow-up, 26 patients (50.0%) had at least one CVD event and 8 patients (15.4%) died. The mean plasma M-CSF concentration increased in survivors after follow-up compared to that detected at baseline (1277.8 ± 693.3 vs. 997.2 ± 417.4 pg/mL; p <  0.05). Multivariate Cox regression analysis showed that plasma M-CSF is an independent risk factor for CVD events in HD patients (p <  0.05). In the Cox regression model after adjusting for gender and age, high M-CSF levels were related to an increased risk of all-cause death (p <  0.05). We also found that M-CSF levels were positively correlated with IL-6 and IL-18 levels (both p < 0.05), which are the major pathogentic cytokines that contribute to HD-related CVD events.

Conclusion

M-CSF is a prognostic factor for CVD events and all-cause mortality in HD patients.

C-Reactive Protein Promotes Inflammation through FcγR-Induced Glycolytic Reprogramming of Human Macrophages

C-reactive protein (CRP) is an acute-phase protein produced in high quantities by the liver in response to infection and during chronic inflammatory disorders. Although CRP is known to facilitate the clearance of cell debris and bacteria by phagocytic cells, the role of CRP in additional immunological functions is less clear. This study shows that complexed CRP (phosphocholine [PC]:CRP) (formed by binding of CRP to PC moieties), but not soluble CRP, synergized with specific TLRs to posttranscriptionally amplify TNF, IL-1β, and IL-23 production by human inflammatory macrophages. We identified FcγRI and IIa as the main receptors responsible for initiating PC:CRP-induced inflammation. In addition, we identified the underlying mechanism, which depended on signaling through kinases Syk, PI3K, and AKT2, as well as glycolytic reprogramming. These data indicate that in humans, CRP is not only a marker but also a driver of inflammation by human macrophages. Therefore, although providing host defense against bacteria, PC:CRP-induced inflammation may also exacerbate pathology in the context of disorders such as atherosclerosis.

Role of C-Reactive Protein at Sites of Inflammation and Infection

C-reactive protein (CRP) is an acute inflammatory protein that increases up to 1,000-fold at sites of infection or inflammation. CRP is produced as a homopentameric protein, termed native CRP (nCRP), which can irreversibly dissociate at sites of inflammation and infection into five separate monomers, termed monomeric CRP (mCRP). CRP is synthesized primarily in liver hepatocytes but also by smooth muscle cells, macrophages, endothelial cells, lymphocytes, and adipocytes. Evidence suggests that estrogen in the form of hormone replacement therapy influences CRP levels in the elderly. Having been traditionally utilized as a marker of infection and cardiovascular events, there is now growing evidence that CRP plays important roles in inflammatory processes and host responses to infection including the complement pathway, apoptosis, phagocytosis, nitric oxide (NO) release, and the production of cytokines, particularly interleukin-6 and tumor necrosis factor-α. Unlike more recent publications, the findings of early work on CRP can seem somewhat unclear and at times conflicting since it was often not specified which particular CRP isoform was measured or utilized in experiments and whether responses attributed to nCRP were in fact possibly due to dissociation into mCRP or lipopolysaccharide contamination. In addition, since antibodies for mCRP are not commercially available, few laboratories are able to conduct studies investigating the mCRP isoform. Despite these issues and the fact that most CRP research to date has focused on vascular disorders, there is mounting evidence that CRP isoforms have distinct biological properties, with nCRP often exhibiting more anti-inflammatory activities compared to mCRP. The nCRP isoform activates the classical complement pathway, induces phagocytosis, and promotes apoptosis. On the other hand, mCRP promotes the chemotaxis and recruitment of circulating leukocytes to areas of inflammation and can delay apoptosis. The nCRP and mCRP isoforms work in opposing directions to inhibit and induce NO production, respectively. In terms of pro-inflammatory cytokine production, mCRP increases interleukin-8 and monocyte chemoattractant protein-1 production, whereas nCRP has no detectable effect on their levels. Further studies are needed to expand on these emerging findings and to fully characterize the differential roles that each CRP isoform plays at sites of local inflammation and infection.

Syncytin-1, an endogenous retroviral protein, triggers the activation of CRP via TLR3 signal cascade in glial cells

Schizophrenia is a devastating psychiatric disorder that impacts on social functioning and quality of life, and there is accumulating evidence that inflammation is a potential pathogenic mechanism of schizophrenia. However, the mechanism of inflammation possibly occurred in schizophrenia has not been well understood. The endogenous retroviral protein syncytin-1 and inflammatory marker CRP are both abnormally expressed in schizophrenia patients. CRP is one of the markers of bacterial infection generally. Less clear is whether virus or viral protein can trigger the activation of CRP. Here, we detected a robust increase of the levels of syncytin-1 and CRP in schizophrenia patients, and displayed a positive correlation and marked consistency between expressions of syncytin-1 and CRP in schizophrenia patients. Furthermore, overexpression of syncytin-1 significantly elevated the levels of CRP, TLR3, and IL-6 in both human microglia and astrocytes. TLR3 deficiency impaired the expressions of CRP and IL-6 induced by syncytin-1. Importantly, we observed a cellular co-localization and a direct interaction between syncytin-1 and TLR3. Additionally, knockdown of IL-6 inhibited the syncytin-1-induced CRP expression. Thus, the totality of these results showed that viral protein syncytin-1 could trigger the activation of CRP, which might explain the elevated CRP in sterile inflammation and exhibit a novel mechanism for regulation of inflammation by syncytin-1 in schizophrenia.

Stimulation of Erythrocyte Cell Membrane Scrambling by C-Reactive Protein

Background: Eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and phosphatidylserine-translocation, is triggered by fever and inflammation. Signaling includes increased cytosolic Ca2+-activity ([Ca2+]i), caspase activation, and ceramide. Inflammation is associated with increased plasma concentration of C-reactive protein (CRP). The present study explored whether CRP triggers eryptosis. Methods: Phosphatidylserine abundance at the cell surface was estimated from annexin-V-binding, cell volume from forward scatter, [Ca2+]i from Fluo3-fluorescence, ceramide abundance and caspase-3-activity utilizing FITC-conjugated antibodies. Moreover, blood was drawn from patients with acute appendicitis (9♀,11♂) and healthy volunteers (10♀,10♂) for determination of CRP, blood count and phosphatidylserine. Results: A 48h CRP treatment significantly increased the percentage of annexin-V-binding cells (≥5µg/ml), [Ca2+]i (≥5µg/ml), ceramide (20µg/ml) and caspase-activity (20µg/ml). Annexin-V-binding was significantly blunted by caspase inhibitor zVAD (10µM). The percentage of phosphatidylserine-exposing erythrocytes in freshly drawn blood was significantly higher in appendicitis patients (1.83±0.21%) than healthy volunteers (0.81±0.09%), and significantly higher following a 24h incubation of erythrocytes from healthy volunteers to patient plasma than to plasma from healthy volunteers. The percentage of phosphatidylserine-exposing erythrocytes correlated with CRP plasma concentration. Conclusion: C-reactive protein triggers eryptosis, an effect at least partially due to increase of [Ca2+]i, increase of ceramide abundance and caspase activation.

Monomethylarsonous acid, but not inorganic arsenic, is a mitochondria-specific toxicant in vascular smooth muscle cells

Arsenic exposure has been implicated as a risk factor for cardiovascular diseases, metabolic disorders, and cancer, yet the role mitochondrial dysfunction plays in the cellular mechanisms of pathology is largely unknown. To investigate arsenic-induced mitochondrial dysfunction in vascular smooth muscle cells (VSMCs), we exposed rat aortic smooth muscle cells (A7r5) to inorganic arsenic (iAs(III)) and its metabolite monomethylarsonous acid (MMA(III)) and compared their effects on mitochondrial function and oxidative stress. Our results indicate that MMA(III) is significantly more toxic to mitochondria than iAs(III). Exposure of VSMCs to MMA(III), but not iAs(III), significantly decreased basal and maximal oxygen consumption rates and concomitantly increased compensatory extracellular acidification rates, a proxy for glycolysis. Treatment with MMA(III) significantly increased hydrogen peroxide and superoxide levels compared to iAs(III). Exposure to MMA(III) resulted in significant decreases in mitochondrial ATP, aberrant perinuclear clustering of mitochondria, and decreased mitochondrial content. Mechanistically, we observed that mitochondrial superoxide and hydrogen peroxide contribute to mitochondrial toxicity, as treatment of cells with MnTBAP (a mitochondrial superoxide dismutase mimetic) and catalase significantly reduced mitochondrial respiration deficits and cell death induced by both arsenic compounds. Overall, our data demonstrates that MMA(III) is a mitochondria-specific toxicant that elevates mitochondrial and non-mitochondrial sources of ROS.

Biomarkers to enhance accuracy and precision of prediction of short-term and long-term outcome after spontaneous intracerebral haemorrhage: a study protocol for a prospective cohort study

BACKGROUND

Several studies reported prognostic value of biomarker in intracerebral hemorrhagic (ICH) but they are either preliminary observation or inadequately powered to analyse independent contribution of biomarkers over and above clinical and neuroimaging data.

OBJECTIVE

To examine whether the biomarker can significantly add to the predictive accuracy of prognosis of ICH.

METHOD/DESIGN

In a multi-centric prospective cohort study, 1020 patients with ICH within 72 hours of onset are being recruited. After obtaining written informed consent from patients/proxy, venous blood sample (10 ml) is being collected and analysed for C-reactive protein (CRP) level, S100B, Glial fibrillary acidic protein (GFAP), Troponin, change in leukocyte count and Copeptin levels. The patients are telephonically followed using stroke scales (Barthel Index and modified Rankin Scale) at 3, 6, 12 months and 2 years after the recruitment.

DISCUSSION

This protocol will aim at predicting the short term or long term prognosis with the use of clinical, neuroimaging and biomarkers in order to help clinician to stratify patients for early referral or intervention.

Fcγ receptors and ligands and cardiovascular disease

Fcγ receptors (FcγRs) classically modulate intracellular signaling on binding of the Fc region of IgG in immune response cells. How FcγR and their ligands affect cardiovascular health and disease has been interrogated recently in both preclinical and clinical studies. The stimulation of activating FcγR in endothelial cells, vascular smooth muscle cells, and monocytes/macrophages causes a variety of cellular responses that may contribute to vascular disease pathogenesis. Stimulation of the lone inhibitory FγcR, FcγRIIB, also has adverse consequences in endothelial cells, antagonizing NO production and reparative mechanisms. In preclinical disease models, activating FcγRs promote atherosclerosis, whereas FcγRIIB is protective, and activating FcγRs also enhance thrombotic and nonthrombotic vascular occlusion. The FcγR ligand C-reactive protein (CRP) has undergone intense study. Although in rodents CRP does not affect atherosclerosis, it causes hypertension and insulin resistance and worsens myocardial infarction. Massive data have accumulated indicating an association between increases in circulating CRP and coronary heart disease in humans. However, Mendelian randomization studies reveal that CRP is not likely a disease mediator. CRP genetics and hypertension warrant further investigation. To date, studies of genetic variants of activating FcγRs are insufficient to implicate the receptors in coronary heart disease pathogenesis in humans. However, a link between FcγRIIB and human hypertension may be emerging. Further knowledge of the vascular biology of FcγR and their ligands will potentially enhance our understanding of cardiovascular disorders, particularly in patients whose greater predisposition for disease is not explained by traditional risk factors, such as individuals with autoimmune disorders.

Pentraxins: structure, function, and role in inflammation

The pentraxins are an ancient family of proteins with a unique architecture found as far back in evolution as the Horseshoe crab. In humans the two members of this family are C-reactive protein and serum amyloid P. Pentraxins are defined by their sequence homology, their pentameric structure and their calcium-dependent binding to their ligands. Pentraxins function as soluble pattern recognition molecules and one of the earliest and most important roles for these proteins is host defense primarily against pathogenic bacteria. They function as opsonins for pathogens through activation of the complement pathway and through binding to Fc gamma receptors. Pentraxins also recognize membrane phospholipids and nuclear components exposed on or released by damaged cells. CRP has a specific interaction with small nuclear ribonucleoproteins whereas SAP is a major recognition molecule for DNA, two nuclear autoantigens. Studies in autoimmune and inflammatory disease models suggest that pentraxins interact with macrophage Fc receptors to regulate the inflammatory response. Because CRP is a strong acute phase reactant it is widely used as a marker of inflammation and infection.

Homocysteine and C-reactive protein associated with progression and prognosis of intracranial branch atheromatous disease

BACKGROUND AND OBJECTIVES

C-reactive protein (CRP) is a biomarker of inflammation and a sensitive predictor of stroke, and high homocysteine (Hcy) is also associated with stroke. However, the roles of CRP and Hcy in the pathogenesis, progression and prognosis of branch atheromatous disease (BAD) and lipohyalinotic degeneration (LD) are largely unknown. We sought to determine the relation between them in Chinese patients.

METHODS

According to the lesion presences shown by diffusion-weighted imaging (DWI), we retrospectively recruited a cohort of 308 patients with a diagnosis of BAD and LD from a total of 1458 consecutive patients with acute ischemic stroke. Progression was defined as worsening by > or  = 1-point in the NIHSS for motor function within the first 5 days. Good outcome was deemed as Modified Rankin Scale (mRS) ≤ 2 and poor outcome was mRS > 2 recorded at one month after onset.

RESULTS

This study comprised a total of 179 patients with BAD and 129 patients with LD. Subjects in patients with LD significantly had an elevated Hcy (p = 0.030), a lower NIHSS score on admission (p<0.001) and mRS score at one month after ictus (p<0.001) than those in patients with BAD. Elevated Hcy (P = 0.004) and increased CRP (P = 0.025) were associated with progression in patients with BAD, and CRP (p = 0.006) and diabetes mellitus (p = 0.011) were found to be associated with poor outcome in patients with BAD. However, no association was observed in patients with LD on progression and prognosis. After multivariate logistic regression analysis, elevated Hcy (p = 0.002) remained the only independent predictor for the progression, and increased CRP (p = 0.027) and smoking (p = 0.012) became the independent predictors for the poor outcome in patients with BAD.

CONCLUSIONS

In patients with BAD, elevated Hcy and increased CRP may independently predict progression and prognosis, respectively.

New aspects of gene-silencing for the treatment of cardiovascular diseases

Coronary heart disease (CHD), mainly caused by atherosclerosis, represents the single leading cause of death in industrialized countries. Besides the classical interventional therapies new applications for treatment of vascular wall pathologies are appearing on the horizon. RNA interference (RNAi) represents a novel therapeutic strategy due to sequence-specific gene-silencing through the use of small interfering RNA (siRNA). The modulation of gene expression by short RNAs provides a powerful tool to theoretically silence any disease-related or disease-promoting gene of interest. In this review we outline the RNAi mechanisms, the currently used delivery systems and their possible applications to the cardiovascular system. Especially, the optimization of the targeting and transfection procedures could enhance the efficiency of siRNA delivery drastically and might open the way to clinical applicability. The new findings of the last years may show the techniques to new innovative therapies and could probably play an important role in treating CHD in the future.

Inflammatory activation: cardiac, renal, and cardio-renal interactions in patients with the cardiorenal syndrome

Although inflammation is a physiologic response designed to protect us from infection, when unchecked and ongoing it may cause substantial harm. Both chronic heart failure (CHF) and chronic kidney disease (CKD) are known to cause elaboration of several pro-inflammatory mediators that can be detected at high concentrations in the tissues and blood stream. The biologic sources driving this chronic inflammatory state in CHF and CKD are not fully established. Traditional sources of inflammation include the heart and the kidneys which produce a wide range of pro-inflammatory cytokines in response to neurohormones and sympathetic activation. However, growing evidence suggests that non-traditional biomechanical mechanisms such as venous and tissue congestion due to volume overload are also important as they stimulate endotoxin absorption from the bowel and peripheral synthesis and release of pro-inflammatory mediators. Both during the chronic phase and, more rapidly, during acute exacerbations of CHF and CKD, inflammation and congestion appear to amplify each other resulting in a downward spiral of worsening cardiac, vascular, and renal functions that may negatively impact patients' outcome. Anti-inflammatory treatment strategies aimed at attenuating end organ damage and improving clinical prognosis in the cardiorenal syndrome have been disappointing to date. A new therapeutic paradigm may be needed, which involves different anti-inflammatory strategies for individual etiologies and stages of CHF and CKD. It may also include specific (short-term) anti-inflammatory treatments that counteract inflammation during the unsettled phases of clinical decompensation. Finally, it will require greater focus on volume overload as an increasingly significant source of systemic inflammation in the cardiorenal syndrome.

Inflammatory markers in coronary artery disease

Coronary artery disease (CAD) is one of the most common manifestations of atherosclerosis. Inflammation is considered one of the major processes that contribute to atherogenesis. Inflammation plays an important role not only on the initiation and progression of atherosclerosis but also on plaque rupture, an event that leads to acute vascular events. Various biomarkers express different pathways and pathophysiologic mechanisms of cardiovascular disease, and inflammatory biomarkers express different parts of the atherogenic process, regarding the initiation and progression of atherosclerosis or the destabilization of the atherosclerotic plaque. Therefore, inflammatory biomarkers may prove to be useful in the detection, staging, and prognosis of patients with CAD. Furthermore, the fact that inflammatory processes are essential steps in the course of the disease offers future therapeutic targets for the interruption of the atherogenic process or for the management of acute events.

Targeting C/EBP homologous protein with siRNA attenuates cerebral vasospasm after experimental subarachnoid hemorrhage

Endothelial apoptosis plays a major role in the development of cerebral vascular spasm after subarachnoid hemorrhage (SAH). C/EBP homologous protein (CHOP) orchestrates apoptosis in a variety of cell types in response to endoplasmic reticulum (ER) stress, implicated in the brain injury after SAH. However, the role of CHOP in the mechanism of cerebral vasospasm (CVS) after SAH remains unexplored. The aim of this study was to evaluate the effect of CHOP silencing on endothelial apoptosis and CVS following subarachnoid hemorrhage in the rat. The study was conducted on 65 rats and employed endovascular perforation model of SAH. CHOP siRNAs were injected 24 h prior to the hemorrhage. At 72 h after SAH brains with basilar arteries (BA) were collected from euthanized rats for laboratory investigations. Triple fluorescence stain revealed expression of CHOP in cerebral vascular endothelia after SAH. Marked reduction of CHOP protein and the reduction of its downstream signaling effectors, bim and caspase-3, were found in BA with Western blot analysis. CHOP silencing reduced number of apoptotic endothelial cells in BA, and increased BA diameter after SAH. The amelioration of CVS was associated with reduced neuronal injury in cerebral tissues. In conclusion, CHOP siRNA treatment can effectively combat apoptotic mechanisms of cerebral vasospasm set in motion by subarachnoid bleeding.

Membrane curvature recognition by C-reactive protein using lipoprotein mimics

It has been reported that the oxidation of phosphatidylcholine (PC) is necessary for C-reactive protein (CRP) to bind to lipid membranes, but it remains elusive why CRP only binds oxidized membranes. Here we offer a new perspective on the role of membrane curvature and CRP binding using engineered lipoprotein particle (LPP) mimics. We show that CRP binds preferentially to LPP mimics with diameters of ≤ 28 nm, and binding of CRP to these mimics leads to the dissociation of native CRP into monomeric CRP, exposing CRP neo-epitopes that bind C1q. We also show that the smaller LPP mimics compete for CRP binding to oxidized low density lipoproteins (oxLDLs), suggesting that these mimics expose the same PC epitopes as those found on oxLDLs. Results from this study suggest that membrane curvature could be an additional factor influencing CRP binding of damaged membranes distinct from the oxidation of PC lipids.

Monomeric C-reactive protein alters fibrin clot properties on endothelial cells

Elevated plasma levels of C-reactive protein (CRP) are independently associated with increased risk of atherothrombosis. Several lines of evidence suggest that CRP has prothrombogenic effects on injured vessel wall(s) by enhancing tissue factor (TF) expression. Abnormal fibrin formation is correlated with increased thrombotic risk. However, the impact of localized, cell surface-driven in situ tissue factor generation by CRP on clot dynamics and fibrin architecture has not previously been evaluated. We examined the impact of native CRP and modified or monomeric CRP (mCRP) on the fibrin formation and structure in Human Umbilical Vein Endothelial Cells (HUVECs). Fibrin formation and structure were examined using laser scanning confocal microscopy. Incubation with mCRP on the cell surface had faster fibrin polymerization by the analysis of turbidimetry. Confocal microscopy of fibrin clots showed a significantly increased density in the treatment of mCRP compared with native CRP and control in the proximal versus distal relationship to the cell surface. The increased expression and activity of TF on the cell surface was observed by addition of mCRP. Blockage of tissue factor and lipid rafts significantly reduced the density of fibrin network produced by mCRP-stimulated endothelial cells. mCRP changes clot dynamics and alters fibrin architecture by enhancing TF on the endothelial cell surface. These results support the concept that elevated CRP levels may induce fibrinolytic resistance and endothelial dysfunction by altering fibrin clot structure.

Is there a common upstream link for autophagic and apoptotic cell death in human high-grade gliomas?

The prognosis of patients with human high-grade gliomas (HGGs) remains dismal despite major advances in their management, due mainly to the high resistance of these infiltrative tumor cells to programmed cell death (PCD). Most therapeutic strategies for HGGs are aimed to maximize PCD type I, apoptosis or type II, autophagy. These are predominantly distinctive processes, but many studies suggest a cross-talk between the two. A better understanding of the link between PCD types I and II might allow development of more effective therapies for HGGs. In this study, we examined whether there is a common upstream signaling event responsible for both apoptotic and autophagic PCD using 3 chemotherapeutic agents in human HGG cells. Our study shows that each agent caused a significant decrease in cell viability in each of the HGG cell lines tested. The increase rate of apoptosis and autophagy varied among cell lines and chemotherapeutic agents used. Increased expression of cytidine-cytidine-adenosine-adenosine-thymidine (C)/enhancer binding protein (EBP) homologous transcription factor C/EBP homologous protein (CHOP)/growth arrest and DNA damage-inducible gene 153 (GADD153) was documented after use of either pro-autophagic or pro-apoptotic agents. The involvement of CHOP/GADD153 in both type I and type II PCD was confirmed by overexpression and gene-silencing studies. Gene silencing by small-interfering RNA-mediated CHOP/GADD153 resulted in increased cell viability, decreased upregulation of microtubule-associated protein light-chain 3' type II (LC3II) and cleaved caspase-3, and inhibition of apoptosis and autophagy. Exogenous expression of CHOP/GADD153 triggered apoptosis and autophagy in the absence of other stimuli. The clinical significance of these findings was supported by the evidence that celecoxib, a nonsteroidal anti-inflammatory drug known to induce GADD153-mediated apoptosis, strongly increases both type I and type II PCD in HGG cells when combined with another inducer of GADD153. These data suggest that CHOP/GADD153 should be investigated as a novel targetable signaling step to improve therapies for HGGs.

Opposing effects of monomeric and pentameric C-reactive protein on endothelial progenitor cells

C-reactive protein (CRP) has been linked to the pathogenesis of atherosclerosis. The dissociation of native, pentameric (p)CRP to monomeric (m)CRP on the cell membrane of activated platelets has recently been demonstrated. The dissociation of pCRP to mCRP may explain local pro-inflammatory reactions at the site of developing atherosclerotic plaques. As a biomarker, pCRP predicts cardiovascular adverse events and so do reduced levels and function of circulating endothelial progenitor cells (EPCs). We hypothesised that mCRP and pCRP exert a differential effect on EPC function and differentiation. EPCs were treated with mCRP or pCRP for 72 h, respectively. Phenotypical characterisation was done by flow cytometry and immunofluorescence microscopy, while the effect of mCRP and pCRP on gene expression was examined by whole-genome gene expression analysis. The functional capacity of EPCs was determined by colony forming unit (CFU) assay and endothelial tube formation assay. Double staining for acetylated LDL and ulex lectin significantly decreased in cells treated with pCRP. The length of tubuli in a matrigel assay with HUVECs decreased significantly in response to pCRP, but not to mCRP. The number of CFUs increased after pCRP treatment. RNA expression profiling demonstrated that mCRP and pCRP cause highly contradictory gene regulation. Interferon-responsive genes (IFI44L, IFI44, IFI27, IFI 6, MX1, OAS2) were among the highly up-regulated genes after mCRP, but not after pCRP treatment. In conclusion, EPC phenotype, genotype and function were differentially affected by mCRP and pCRP, strongly arguing for differential roles of these two CRP conformations. The up-regulation of interferon-inducible genes in response to mCRP may constitute a mechanism for the local regulation of EPC function.

C-reactive protein induces p53-mediated cell cycle arrest in H9c2 cardiac myocytes

C-reactive protein (CRP) is one of the most important biomarker for cardiovascular diseases. Recent studies have shown that CRP affects cell survival, differentiation and apoptosis. However, the effect of CRP on the cell cycle has not been studied yet. We investigated the cell cycle alterations and cellular mechanisms induced by CRP in H9c2 cardiac myocytes. Flow cytometry analysis showed that CRP-treated H9c2 cells displayed cell cycle arrest in G0/G1 phase. CRP treatment resulted in a significant reduction in the levels of CDK4, CDK6 and cyclin D1 in a concentration-dependent manner. Interestingly, CRP caused an increase in the p53 accumulation and its phosphorylation on Ser15, leading to induce p21 upregulation. Treatment with a specific p53 inhibitor, PFT-α restored the levels of CDK4 and CDK6. A significant increase of ERK1/2 phosphorylation level was detected in CRP-treated cells. Furthermore, pretreatment of a specific ERK inhibitor resulted in decreased p53 phosphorylation and p21 induction. ERK inhibitor pretreatment induced significant restoration of protein levels of CDK4 and CDK6, leading to re-entry into the cell cycle. In addition, increased phosphorylation of p53 and ERK induced by CRP was considerably reversed by Fc gamma receptor IIIa (FcγRIIIa) knock-down using siRNA. FcγRIIIa siRNA transfection also restored the levels of cell cycle proteins. Our study has provided the first proposal on the novel insights into how CRP directly affects cell cycle in cells.

Time course analysis of gene expression identifies multiple genes with differential expression in patients with in-stent restenosis

BACKGROUND

The vascular disease in-stent restenosis (ISR) is characterized by formation of neointima and adverse inward remodeling of the artery after injury by coronary stent implantation. We hypothesized that the analysis of gene expression in peripheral blood mononuclear cells (PBMCs) would demonstrate differences in transcript expression between individuals who develop ISR and those who do not.

METHODS AND RESULTS

We determined and investigated PBMC gene expression of 358 patients undergoing an index procedure to treat in de novo coronary artery lesions with bare metallic stents, using a novel time-varying intercept model to optimally assess the time course of gene expression across a time course of blood samples. Validation analyses were conducted in an independent sample of 97 patients with similar time-course blood sampling and gene expression data. We identified 47 probesets with differential expression, of which 36 were validated upon independent replication testing. The genes identified have varied functions, including some related to cellular growth and metabolism, such as the NAB2 and LAMP genes.

CONCLUSIONS

In a study of patients undergoing bare metallic stent implantation, we have identified and replicated differential gene expression in peripheral blood mononuclear cells, studied across a time series of blood samples. The genes identified suggest alterations in cellular growth and metabolism pathways, and these results provide the basis for further specific functional hypothesis generation and testing of the mechanisms of ISR.

Low-level C-reactive protein levels exert cytoprotective actions on human podocytes

BACKGROUND

Albuminuria and elevated C-reactive protein (CRP) levels are common manifestations of many inflammatory diseases. Cardiovascular-based drugs, with secondary anti-inflammatory actions, such as angiotensin-converting enzyme-inhibitors are able to reduce both proteinuria and CRP levels, raising the question of whether CRP directly influences the processes that result in proteinuria. As proteinuria is thought to be induced as a result of podocyte dysfunction, we investigated whether there is a pathomechanistic link with CRP.

METHODS

Podocytes were analysed for evidence of endogenous CRP production in response to inflammatory agents. In addition, they were incubated in the presence of various concentrations of exogenous CRP and analysed for evidence of a response to treatment.

RESULTS

Our results demonstrated that inflammatory agents such as macrophage-conditioned medium and interleukin-1β induced the expression of CRP messenger RNA in podocytes. However, they were unable to induce CRP protein. Stimulation of podocytes with exogenous CRP demonstrated that 10 μg/mL CRP induced a low but significant level of interleukin-6 secretion. Tumour necrosis factor α, however, was not detected. CRP did up-regulate the expression of the slit diaphragm proteins nephrin and CD2AP, as well as the structural proteins ezrin and podocalyxin-like protein-1, proteins known to be involved in signalling via the phosphotidylinositol-3 (PI-3) kinase pathway. CRP exposure reduced caspase-3 enzyme activity and up-regulated the expression of the anti-apoptotic protein Bcl-2. In the presence of the PI-3 kinase inhibitor LY294002, the ability of CRP to suppress caspase-3 activity was significantly reduced.

CONCLUSIONS

Taken together, these data suggest that rather than inducing podocyte damage, CRP may be a survival factor for podocytes by maintaining their structural integrity and initiating a survival cascade, which may facilitate podocyte recovery from injury.

Overproduction of cyclo-oxygenase-2 (COX-2) is involved in the resistance to apoptosis in vascular smooth muscle cells from diabetic patients: a link between inflammation and apoptosis

AIMS/HYPOTHESIS

Inflammation is a common feature in cardiovascular diseases, including diabetes mellitus. In addition to the well-known inflammatory role of cyclo-oxygenase-2 (COX-2), this protein has also been implicated in apoptosis resistance in tumour cells. Vascular smooth muscle cells (VSMC) from diabetic patients are also resistant to apoptosis because of an increased abundance of B cell lymphoma 2 protein (BCL2). In this work, we investigated whether overproduction of COX-2 was involved in the resistance to apoptosis in VSMC from diabetic patients.

METHODS

VSMC were obtained from internal mammary arteries from patients who had undergone coronary artery bypass graft surgery. Apoptosis was measured by DNA fragmentation, BCL2 degradation and cytochrome c release.

RESULTS

Apoptosis induced by C-reactive protein in cells from non-diabetic patients was mediated by COX-2. VSMC from diabetic patients showed higher basal levels of COX-2 compared with those from non-diabetic patients. Transfection of VSMC from non-diabetic patients with a plasmid containing COX-2 (also known as PTGS2) increased basal production of COX-2 and BCL2 and mimicked the resistance to apoptosis that occurs in diabetic patients. We also found a significant correlation (R = 0.846, p = 0.016) between COX-2 and BCL2 production in arterial rings from diabetic patients measured by confocal microscopy. However, inhibition of COX-2 production by small interfering RNA proved unable to reverse BCL2 production in diabetic VSMC.

CONCLUSIONS/INTERPRETATION

These results suggest a link between inflammation (COX-2) and apoptosis resistance (BCL2) in the arteries of diabetic patients. This relationship is not causative and the common production of these two proteins may be co-regulated by shared regulatory elements in diabetes.

Increased C-reactive protein expression exacerbates left ventricular dysfunction and remodeling after myocardial infarction

We previously reported serum C-reactive protein (CRP) elevation after acute myocardial infarction (MI) to be associated with adverse outcomes including cardiac rupture, left ventricular (LV) remodeling, and cardiac death. Experimental studies have indicated that CRP per se has various biological actions including proinflammatory and proapoptotic effects, suggesting a pathogenic role of CRP in the post-MI remodeling process. We tested the hypothesis that increased CRP expression would exacerbate adverse LV remodeling after MI via deleterious effects of CRP. Transgenic mice with human CRP expression (CRP-Tg) and their transgene-negative littermates (control) underwent left coronary artery ligation. There was no apparent difference in phenotypic features between CRP-Tg and control mice before MI. Although mortality and infarct size were similar in the two groups, CRP-Tg mice showed more LV dilation and worse LV function with more prominent cardiomyocyte hypertrophy and fibrosis in the noninfarcted regions after MI than controls. Histological evaluation conducted 1 wk post-MI revealed a higher rate of apoptosis and more macrophage infiltration in the border zones of infarcted hearts from CRP-Tg mice in relation to increased monocyte chemotactic protein (MCP)-1 expression and matrix metalloproteinase (MMP)-9 activity. Increased CRP expression exacerbates LV dysfunction and promotes adverse LV remodeling after MI in mice. The deleterious effect of CRP on post-MI LV remodeling may be associated with increased apoptotic rates, macrophage infiltration, MCP-1 expression, and MMP-9 activity in the border zone.

Carotid plaque, stroke pathogenesis, and CRP: treatment of ischemic stroke

Inflammation is receiving increased attention as a cause of atherosclerosis and stroke. Several inflammatory biomarkers, and particularly high-sensitivity C-reactive protein (hsCRP), have been identified as likely predictors of the risk of a future stroke. In clinical settings, it has been consistently observed that higher concentrations of CRP are associated with larger brain infarcts, stroke severity, neurologic disability, and future vascular events. However, there is still controversy over the degree of risk conferred by elevated CRP concentrations. Some studies reported that the predictive value of CRP is moderate compared with classical risk factors and is only weakly related to cardiovascular damage after adjustment for traditional cardiovascular risk factors. CRP like many other hemostatic factors is an acute-phase protein and, therefore, it is not always clear whether its association with cerebrovascular disease reflects its contribution to atherothrombosis, its acute-phase condition, or both. Furthermore, the value of single measurements of CRP in patients with concurrent infection or other inflammatory conditions has not been established and reported data should be interpreted cautiously. Several drugs, especially hydroxymethylglutaryl coenzyme A reductase inhibitors (statins), have been demonstrated to reduce hsCRP levels independently of their effects on plasma cholesterol. Recently, emerging therapies have been aimed at the control of blood pressure and inflammation in stroke patients. Whether a reduction of hsCRP levels could be beneficial to stroke patients remains to be clarified, and it is also unclear whether other drugs may be useful to lower hsCRP levels. More studies are needed before hsCRP becomes a routine part of the evaluation of stroke patients. This should also prompt the search for new agents directly blocking CRP actions.

Desipramine induces apoptosis in rat glioma cells via endoplasmic reticulum stress-dependent CHOP pathway

Various antidepressants, mainly tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs), have exhibited potent anticancer properties in different cancer cell types. In the present study, desipramine (DMI), a representative of TCAs, was examined with respect to its apoptosis-inducing activity in rat C6 glioma cells and the underlying mechanism of action. DMI induced typical apoptotic morphology of chromatin condensation in rat glioma C6 cells and activated intracellular caspase 9 and caspase 3 with no change in mitochondrial membrane potential. Simultaneously, DMI significantly elevated expression of endoplasmic reticulum stress regulator CHOP/GADD153 and its targeting molecule GADD34. However, knockdown of CHOP by CHOP-specific short interfering RNA (siRNA) could decrease the activity of intracellular caspase 3 and the cytotoxicity of DMI to C6 cells. These results revealed that the CHOP-dependent endoplasmic reticulum (ER) stress pathway is responsible for DMI-induced apoptosis in C6 cells.

Repetitive element DNA methylation and circulating endothelial and inflammation markers in the VA normative aging study

BACKGROUND

Lower blood DNA methylation has been associated with atherosclerosis and high cardiovascular risk. Mechanisms linking DNA hypomethylation to increased cardiovascular risk are still largely unknown. In a population of community-dwelling elderly individuals, we evaluated whether DNA methylation in LINE-1 repetitive element, heavily methylated sequences dispersed throughout the human genome, was associated with circulating Vascular Cell Adhesion Molecule-1 (VCAM-1), Inter- Cellular Adhesion Molecule-1 (ICAM-1), and C-reactive protein (CRP).

METHODS AND RESULTS

We measured LINE-1 methylation by bisulfite PCR-Pyrosequencing on 742 blood DNA samples from male participants in the Boston area Normative Aging Study (mean age=74.8 years). Mean serum VCAM-1 increased progressively in association with LINE-1 hypomethylation (from 975.2 to 1063.4 ng/ml in the highest vs. lowest methylation quintiles; ptrend= 0.004). The association between VCAM-1 and LINE-1 hypomethylation was significant in individuals without ischemic heart disease or stroke (n=480; p=0.001), but not in those with prevalent disease (n=262; p=0.57). Serum ICAM-1 and CRP were not associated with LINE-1 methylation (p-trend=> 0.25). All results were confirmed by multivariable analyses adjusting for age, BMI, smoking, pack-years, and ischemic heart disease/stroke.

CONCLUSIONS

LINE-1 element hypomethylation is associated with higher serum VCAM-1. Our data provide new insights into epigenetic events that may accompany the development of cardiovascular disease.

Therapeutic opportunities of small interfering RNA

Formation of small interfering RNA (siRNA) occurs in two steps involving binding of the RNA nucleases to a large double‐stranded RNA (dsRNA) and its cleavage into fragments called siRNA. In the second step, these siRNAs join a multinuclease complex, which degrades the homologous single‐stranded mRNAs. The delivery of siRNA involves viral‐ and non‐viral‐mediated delivery systems; the approaches for chemical modifications have also been developed. It has various therapeutic applications for disorders like cardiovascular diseases, central nervous system (CNS) disorders, cancer, human immunodeficiency virus (HIV), hepatic disorders, etc. The present review gives an overview of the applications of siRNA and their potential for treating many hitherto untreatable diseases.