Increased platelet activation markers in rheumatoid arthritis: are they related with subclinical atherosclerosis?

A systematic review and meta-analysis of circulating adhesion molecules in rheumatoid arthritis

BACKGROUND

The availability of robust biomarkers of endothelial activation might enhance the identification of subclinical atherosclerosis in rheumatoid arthritis (RA). We investigated this issue by conducting a systematic review and meta-analysis of cell adhesion molecules in RA patients.

METHODS

We searched electronic databases from inception to 31 July 2023 for case-control studies assessing the circulating concentrations of immunoglobulin-like adhesion molecules (vascular cell, VCAM-1, intercellular, ICAM-1, and platelet endothelial cell, PECAM-1, adhesion molecule-1) and selectins (E, L, and P selectin) in RA patients and healthy controls. Risk of bias and certainty of evidence were assessed using the JBI checklist and GRADE, respectively.

RESULTS

In 39 studies, compared to controls, RA patients had significantly higher concentrations of ICAM-1 (standard mean difference, SMD = 0.81, 95% CI 0.62-1.00, p < 0.001; I2 = 83.0%, p < 0.001), VCAM-1 (SMD = 1.17, 95% CI 0.73-1.61, p < 0.001; I2 = 95.8%, p < 0.001), PECAM-1 (SMD = 0.82, 95% CI 0.57-1.08, p < 0.001; I2 = 0.0%, p = 0.90), E-selectin (SMD = 0.64, 95% CI 0.42-0.86, p < 0.001; I2 = 75.0%, p < 0.001), and P-selectin (SMD = 1.06, 95% CI 0.50-1.60, p < 0.001; I2 = 84.8%, p < 0.001), but not L-selectin. In meta-regression and subgroup analysis, significant associations were observed between the effect size and use of glucocorticoids (ICAM-1), erythrocyte sedimentation rate (VCAM-1), study continent (VCAM-1, E-selectin, and P-selectin), and matrix assessed (P-selectin).

CONCLUSIONS

The results of our study support a significant role of cell adhesion molecules in mediating the interplay between RA and atherosclerosis. Further studies are warranted to determine whether the routine use of these biomarkers can facilitate the detection and management of early atherosclerosis in this patient group. PROSPERO Registration Number: CRD42023466662.

Canine diabetes mellitus demonstrates multiple markers of chronic inflammation including Th40 cell increases and elevated systemic-immune inflammation index, consistent with autoimmune dysregulation

Introduction

Canine diabetes mellitus (CDM) is a relatively common endocrine disease in dogs. Many CDM clinical features resemble human type 1 diabetes mellitus (T1DM), but lack of autoimmune biomarkers makes calling the disease autoimmune controversial. Autoimmune biomarkers linking CDM and T1DM would create an alternative model for drug development impacting both human and canine disease.

Methods

We examined peripheral blood of diagnosed CDM dog patients comparing it to healthy control (HC) dogs. Dogs were recruited to a study at the Colorado State University Veterinary Teaching Hospital and blood samples collected for blood chemistry panels, complete blood counts (CBC), and immunologic analysis. Markers of disease progression such as glycated albumin (fructosamine, the canine equivalent of human HbA1c) and c-peptide were addressed.

Results

Significant differences in adaptive immune lymphocytes, innate immune macrophages/monocytes and neutrophils and differences in platelets were detected between CDM and HC based on CBC. Significant differences in serum glucose, cholesterol and the liver function enzyme alkaline phosphatase were also detected. A systemic immune inflammation index (SII) and chronic inflammation index (CII) as measures of dynamic changes in adaptive and innate cells between inflammatory and non-inflammatory conditions were created with highly significant differences between CDM and HC. Th40 cells (CD4+CD40+ T cells) that are demonstrably pathogenic in mouse T1DM and able to differentiate diabetic from non-diabetic subjects in human T1DM were significantly expanded in peripheral blood mononuclear cells.

Conclusions

Based on each clinical finding, CDM can be categorized as an autoimmune condition. The association of significantly elevated Th40 cells in CDM when compared to HC or to osteoarthritis, a chronic but non-autoimmune disease, suggests peripheral blood Th40 cell numbers as a biomarker that reflects CDM chronic inflammation. The differences in SII and CII further underscore those findings.

The genesis of cardiovascular risk in inflammatory arthritis: insights into glycocalyx shedding, endothelial dysfunction, and atherosclerosis initiation

This narrative review provides a comprehensive examination of the complex interplay between inflammatory arthritis (IA) and cardiovascular pathology. It particularly illuminates the roles of atherosclerosis initiation, endothelial dysfunction, and glycocalyx shedding. IA not only provokes tissue-specific inflammatory responses, but also engenders a considerable degree of non-specific systemic inflammation. This review underscores the accelerating influence of the chronic inflammatory milieu of IA on cardiovascular disease (CVD) progression. A focal point of our exploration is the critical function of the endothelial glycocalyx (EG) in this acceleration process, which possibly characterizes the earliest phases of atherosclerosis. We delve into the influence of inflammatory mediators on microtubule dynamics, EG modulation, immune cell migration and activation, and lipid dysregulation. We also illuminate the impact of microparticles and microRNA on endothelial function. Further, we elucidate the role of systemic inflammation and sheddases in EG degradation, the repercussions of complement activation, and the essential role of syndecans in preserving EG integrity. Our review provides insight into the complex and dynamic interface between systemic circulation and the endothelium.

Relevance of circulating markers of endothelial activation for cardiovascular risk assessment in rheumatoid arthritis: a narrative review

Rheumatoid arthritis (RA) is associated with excessive cardiovascular mortality secondary to premature atherosclerosis, in which endothelial activation (EA) plays a central role. EA is characterized by loss of vascular integrity, expression of leucocyte adhesion molecules, transition from antithrombotic to prothrombotic phenotype, cytokines production, shedding of membrane microparticles and recruitment of endothelial progenitor cells. As EA is an early event in atherogenesis, circulating markers of EA are putative markers of vascular pathology and cardiovascular (CV) risk. After a presentation of biology of EA, the present review analyzed the available data regarding changes in EA markers in RA in link with the vascular pathology and CV events, discussed their relevance as biomarkers of CV risk and proposed future directions.

Unique crosstalk between platelet and leukocyte counts during treatment for acute coronary syndrome: A retrospective observational study

In the pathophysiology of acute coronary syndrome (ACS), platelet (PLT) and neutrophil (Neu) crosstalk may be important for activating coagulation and inflammation. It has been speculated that PLTs and Neu may affect each other's cell counts; however, few studies have investigated this hypothesis. In this study, we measured changes in blood cell counts in 245 patients with ACS during treatment and investigated the mutual effects of each blood cell type. Path diagrams were drawn using structural equation modeling, and temporal changes in the count of each blood cell type and the relevance of these changes were analyzed. Throughout the treatment period, the numbers of all blood cell types (red blood cells [RBCs], leukocytes, and PLTs) were associated with each other before and after treatment. A detailed examination of the different cell types revealed that the PLT count at admission had a significant positive effect on the leukocyte (especially Neu) count after treatment. Conversely, the leukocyte (especially Neu) count at admission had a significant positive effect on the PLT count after treatment. During ACS, PLTs and leukocytes, especially Neu, stimulate each other to increase their numbers. The formation of a PLT-leukocyte complex may increase coagulation activity and inflammation, which can lead to a further increase in the counts of both blood cell types.

Platelet extracellular vesicles and the secretory interactome join forces in health and disease

Extracellular vesicles (EVs) are small membrane-bound vesicles released by cells under various conditions. They are found in the extracellular milieu in all biological fluids. As the concentrations, contents, and origin of EVs can change during inflammation, the assessment of EVs can be used as a proxy of cellular activation. Here, we review the literature regarding EVs, more particularly those released by platelets and their mother cells, the megakaryocytes. Their cargo includes cytokines, growth factors, organelles (mitochondria and proteasomes), nucleic acids (messenger and non-coding RNA), transcription factors, and autoantigens. EVs may thus contribute to intercellular communication by facilitating exchange of material between cells. EVs also interact with other molecules secreted by cells. In autoimmune diseases, EVs are associated with antibodies secreted by B cells. By definition, EVs necessarily comprise a phospholipid moiety, which is thus the target of secreted phospholipases also abundantly expressed in the extracellular milieu. We discuss how platelet-derived EVs, which represent the majority of the circulating EVs, may contribute to immunity through the activity of their cargo or in combination with the secretory interactome.

Increase of Circulating Monocyte-Platelet Conjugates in Rheumatoid Arthritis Responders to IL-6 Blockage

Platelets (PLT) bind to a significant percentage of circulating monocytes and this immunomodulatory interaction is increased in several inflammatory and autoimmune conditions. The therapeutic blockage of IL-6 with Tocilizumab (TCZ) alters PLT and the phenotype and function of monocytes in rheumatoid arthritis (RA). However, the relationship between monocyte−PLT conjugates (CD14+PLT+) and clinical and immunological variables and the regulation of this interaction by IL-6 blockage are still unknown. Here, we compared the presence of monocyte−PLT conjugates (CD14+PLT+) and membrane CD162 expression using flow cytometry, and, by ELISA, the markers of PLT activation (sCD62P and sCD40L) in healthy donors (HD) and patients with long-standing RA before TCZ (baseline). We found higher percentages and absolute counts of CD14+PLT+, and higher plasmatic levels of sCD62P and sCD40L but lower CD162 expression on monocytes from RA patients than those from HD. Additionally, the levels of CD14+PLT+ inversely correlated with inflammatory parameters. Interestingly, 95% of patients with lower percentages of CD14+PLT+ and only 63% of patients with higher percentages of CD14+PLT+ achieved a EULAR-defined response at four weeks (p = 0.036). After TCZ, the percentage of CD14+PLT+ increased in 92% of RA patients who achieved 12 w-remission (p < 0.001). Our results suggest that the binding of PLTs has a modulatory effect, accentuated by the increased binding of PLTs to monocytes in response to the therapeutic blockage of IL-6.

Increased Expression of Extracellular Vesicles Is Associated With the Procoagulant State in Patients With Established Rheumatoid Arthritis

This study sought to identify different subpopulations of extracellular vesicles (EVs) in plasma from female patients with established rheumatoid arthritis (RA) in relation to the activation of coagulation and fibrin formation in these patients. Forty women were included in the study, 20 patients and 20 age-matched healthy controls. The mean disease duration in patients was 13.0 (5.0-25.0) years, with medium to high disease activity despite ongoing treatment with low-dose prednisolone and methotrexate. There were no differences between the investigated groups regarding the presence of traditional cardiovascular risk factors. The concentration of phosphatidylserine-positive (PS+) EVs; platelet (CD42a+), leucocyte (CD45+), monocyte (CD14+), and endothelial (CD144+)-derived EVs; and EVs-expressing tissue factor (CD142+), P-selectin (CD62P+), and E-selectin (CD62E+) were determined by flow cytometry analysis. Overall hemostasis potential (OHP) was assessed to follow the hemostatic disturbances, including the parameters for overall coagulation potential (OCP) and overall fibrinolytic potential (OFP). Fibrin clot turbidity was measured together with clot lysis time, and scanning electron microscopy was performed. Increased concentrations of PS+, CD42a+, CD142+, CD45+, CD14+, and CD62P+ EVs were found in plasma from patients with RA compared to healthy controls, and the concentrations of PS+, CD42a+, CD14+, and CD62P+ EVs were positively correlated with the inflammatory parameters in RA patients. Positive correlations were also found between the levels of PS+ and CD42a+ EVs and OCP as well as between the levels of PS+, CD42a+, and CD62P+EVs and OHP. The levels of PS+, CD42a+, CD14+, CD62P+, and CD62E+ EVs were negatively correlated with OFP. Elevated levels of circulating EVs of different cell origins were found in patients with established RA, in relation to the inflammatory burden and coagulation activation in the disease.

Patients with autoimmune chronic inflammatory diseases present increased biomarkers of thromboinflammation and endothelial dysfunction in the absence of flares and cardiovascular comorbidities

Cardiovascular risk is increased in patients with autoimmune rheumatic diseases. Endothelial, erythrocyte and platelet microvesicles (MVs) are elevated in patients with cardiovascular diseases and represent novel markers of endothelial dysfunction and thromboinflammation. We tested whether their levels are increased in patients with autoimmune rheumatic diseases (ARDs) in the absence of disease flare and cardiovascular comorbidities. Well-controlled patients with rheumatoid arthritis or systemic lupus erythematosus were studied, provided they were free from cardiovascular comorbidities and established cardiovascular disease. We additionally studied (a) a control group consisting of healthy volunteers and (b) a reference group including patients with stable coronary artery disease (CAD). MVs were measured using a standardized flow cytometry protocol. In a population of 74 participants, patients with ARDs (n = 17) presented increased levels of both endothelial (283.3 ± 195.0/μL vs 168.5 ± 54.8/μL, p = 0.029) and platelet MVs (374.0 ± 275.3/μL vs 225.7 ± 101.1/μL, p = 0.046) compared to controls (n = 34), whereas erythrocyte MVs did not significantly differ. In addition, patients with ARDs showed similar levels of endothelial MVs compared to CAD patients (n = 23) (283.3 ± 195.0/μL vs 297.0 ± 211.8/μL, p = 0.846). Platelet MVs were significantly associated with disease duration, and erythrocyte MVs with patients' perceived disease activity. In conclusion, increased levels of endothelial and platelet MVs may be evident in patients with ARDs, even in the absence of disease flares and before the establishment of cardiovascular complications. Levels of endothelial MVs resemble those of patients with profound atherothrombotic profile. The prognostic potential of MVs in terms of cardiovascular disease prevention warrants further investigation in patients with ARDs.

Innate immune receptors in platelets and platelet-leukocyte interactions

Platelets are chief cells in hemostasis. Apart from their hemostatic roles, platelets are major inflammatory effector cells that can influence both innate and adaptive immune responses. Activated platelets have thromboinflammatory functions linking hemostatic and immune responses in several physiological and pathological conditions. Among many ways in which platelets exert these functions, platelet expression of pattern recognition receptors (PRRs), including TLR, Nod-like receptor, and C-type lectin receptor families, plays major roles in sensing and responding to pathogen-associated or damage-associated molecular patterns (PAMPs and DAMPs, respectively). In this review, an increasing body of evidence is compiled showing the participation of platelet innate immune receptors, including PRRs, in infectious diseases, sterile inflammation, and cancer. How platelet recognition of endogenous DAMPs participates in sterile inflammatory diseases and thrombosis is discussed. In addition, platelet recognition of both PAMPs and DAMPs initiates platelet-mediated inflammation and vascular thrombosis in infectious diseases, including viral, bacterial, and parasite infections. The study also focuses on the involvement of innate immune receptors in platelet activation during cancer, and their contribution to tumor microenvironment development and metastasis. Finally, how innate immune receptors participate in platelet communication with leukocytes, modulating leukocyte-mediated inflammation and immune functions, is highlighted. These cell communication processes, including platelet-induced release of neutrophil extracellular traps, platelet Ag presentation to T-cells and platelet modulation of monocyte cytokine secretion are discussed in the context of infectious and sterile diseases of major concern in human health, including cardiovascular diseases, dengue, HIV infection, sepsis, and cancer.

Endothelial Dysfunction in Patients with Rheumatoid Arthritis: the Role of Hypertension

PURPOSE OF REVIEW

To review the data on the role of endothelial dysfunction and the impact of hypertension as a potent mediator of cardiovascular disease in patients with rheumatoid arthritis (RA).

RECENT FINDINGS

RA represents the most common autoimmune rheumatic disorder and is characterized by chronic systemic inflammation predisposing to cardiovascular complications. Cardiovascular mortality is increased among patients with RA and represents the leading cause of death. Although the exact prevalence is debated, hypertension is increased in RA. Hypertension acts synergistically with chronic inflammation and accounts, at least partially, for the increased cardiovascular morbidity in this group of patients. Endothelial dysfunction is considered a primary process in the pathogenesis of hypertension and cardiovascular diseases and contributes significantly to the development and progression of the associated micro- and macrovascular complications. Even though several studies in patients with RA have shown the presence of endothelial dysfunction with traditional methods, novel biochemical and vascular methods for the evaluation of endothelial dysfunction have been scarcely applied. In addition, it remains unclear whether and to which extent endothelial dysfunction in RA is present regardless of concomitant hypertension, even in well-controlled patients. Hypertension, endothelial dysfunction, and chronic systemic inflammation appear as a mutually reinforcing triad aggravating cardiovascular risk in patients with RA. Detection of endothelial dysfunction in patients with RA in the early stages further aiming at the development of novel therapeutic targets might contribute to prevention of cardiovascular complications and remains under investigation.

Biomarkers associated with cardiovascular disease in patients with early rheumatoid arthritis

Objectives

Patients with rheumatoid arthritis (RA) have an increased mortality and morbidity due to cardiovascular disease (CVD). In this prospective 5-year follow up of patients with RA, we analysed several biomarkers, known to be associated with atherosclerosis and/or inflammation in the general population. The aim of this study was to find out whether the RA-disease per se affect these biomarkers and if those could be associated with the progression of atherosclerosis, as measured by intima media thickness (IMT) among patients with early RA.

Methods

Patients from northern Sweden diagnosed with early RA, are consecutively recruited into an ongoing prospective study on CVD comorbidity. A subgroup of patients, aged ≤60 years (n = 71) was included for ultrasound measurements of IMT at inclusion (T0) and after 5 years (T5) together with age-sex-matched controls (n = 40). The patients were clinically assessed. Blood was analysed for lipids, ESR and CRP and several biomarkers known to be associated with atherosclerosis in the general population.

Results

At T0, the patients with RA had significantly lower levels of MIF and significantly higher levels of interleukin (IL)-18 and MIC-1 compared with controls. At T5, the patients with RA had significantly higher levels of pentraxin3, MIC-1, TNF-R2, ICAM-1, VCAM-1 and endostatin compared with controls. At T0 the levels of MPO correlated with DAS28, sCD40L with CRP and IL-18 with systolic blood pressure and Reynolds risk score. Using PLSR on a CVD-panel analysed with multiplex immunoassay, the patients with RA could be correctly classified into those who had a worsening in their IMT over the five years or not. Here, MMP3 was identified as influential.

Conclusions

This study indicates that the RA disease itself could affect several of the biomarkers in this study, and possibly also the processes involved in the development of atherosclerosis.

Assessment of CD40 and CD40L expression in rheumatoid arthritis patients, association with clinical features and DAS28

The predominance of the effector mechanisms by CD4 + T cells is a characteristic of inflammatory autoimmune diseases such as rheumatoid arthritis (RA). The CD40/CD40L costimulatory pathway contributes to these pathogenic mechanisms by promoting autoantibody production and inflammation. Aberrant expression of CD40 and CD40L in RA patients has been shown, the latter prevailing in females. However, contrasting results have emerged regarding the clinical associations of these findings. We determined the association of CD40 and CD40L expression with the clinical activity evaluated through DAS28 in RA patients. A total of 38 female RA patients and 10 age- and sex-matched control subjects were included. CD40 and CD40L mRNA expression was quantified by real-time qPCR, cell surface proteins were determined by flow cytometry, and protein soluble forms were determined by ELISA. The expansion of a CD4 + T cell subpopulation expressing CD40 was identified in the RA group. In addition, high frequencies of CD4 + CD40L + T cells expressing high levels of CD40L, increased levels of sCD40L and overexpression of CD40L mRNA were observed in these patients. Moreover, there was a gradual increase in CD40L when data were stratified according to DAS28, except for very active patients. No correlation was observed between the levels of mRNA, cell surface protein and soluble protein of CD40 and CD40L with the clinical features of RA patients. There is an altered expression of CD40L in female RA patients in association with clinical activity assessed by DAS28, these findings support the evidence that suggests CD40L as a marker of clinical activity.

Synergistic enhancement and hepatoprotective effect of combination of total phenolic extracts of Citrus aurantium L. and methotrexate for treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune inflammatory disorder characterized by joint destruction and bone damage. Methotrexate (MTX) is recommended as the first-line disease-modifying agent for the treatment of RA. However, the clinical efficacy of MTX is limited due to its low response and side effects, especially hepatotoxicity. Total phenolic extracts of Citrus aurantium L. (TPE-CA) are rich in dietary bioactive flavonoids, which show beneficial effects on liver health and are regarded as therapeutic tools against inflammatory diseases. In this study, the efficacy of MTX, alone or in combination with TPE-CA, for the treatment of collagen-induced arthritis and protection against hepatic injury in rats was investigated. TPE-CA and MTX combination effectively reduced the inflammatory symptoms and joint damage by inhibiting the NF-κB pathway. Moreover, TPE-CA significantly ameliorated MTX-induced chronic hepatic injury by enhancing antioxidant enzymes activities, suppressing hepatic cytochrome P450 2E1 expression, and modulating the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 pathway. This combination regimen not only provided synergistic enhancement but also exhibited hepatoprotective effect against chemically induced chronic hepatotoxicity. This could be an alternative strategy to improve the low response of MTX in RA treatment.

Association of platelet-derived microvesicles and their phenotypes with carotid atherosclerosis and recurrent vascular events in patients after ischemic stroke

INTRODUCTION

Platelet-derived microvesicles (pMVs) exhibit procoagulant and proinflammatory properties and play a role in the development and progression of atherosclerosis. The study examined the association between the total number of pMVs and their phenotypes with carotid atherosclerosis and recurrent vascular events (VEs) in patients in the convalescent phase of ischemic stroke (IS).

MATERIALS AND METHODS

The study group consisted of 72 patients with IS secondary to large artery atherosclerosis (LAA) (n = 40) and small arteries occlusion (SAO) (n = 32) and 69 matched cardiovascular disease risk-factor (RF) controls. Total pMV number, defined as CD61+ microvesicles (MVs), and their phenotypes, defined as the surface expression of proinflammatory (CD40L, CD62P, CD31) and procoagulant (PS, PAC-1) markers, were characterized and quantified using flow cytometry. The mean common carotid intima-media thickness (CCA mean IMT), maximal common carotid IMT (CCA max IMT) and maximal bifurcation IMT (BIF max IMT) were measured bilaterally using B-mode, color Doppler ultrasonography. All study subjects were observed for one-year to establish the occurrence of VEs.

RESULTS

No differences in pMV parameters between LAA and SAO stroke subjects and between stroke subgroups and controls were found. Stroke patients with carotid atherosclerosis exhibited higher concentration of CD62P+/CD61+ and PAC-1+/CD61+ MVs compared to patients without the atherosclerosis. Positive associations between total number of pMVs, AnV+ MVs and AnV+/CD61+ MVs and atherosclerotic thickening of carotid intima-media in stroke patients were found. Elevated concentration of AnV+/CD61+, PAC-1+/CD61+, CD61P+/CD61+ and CD31+/CD61+ MVs, were revealed in stroke patients who suffered from recurrent VE in one-year follow-up period. Negative correlation of pMVs and CD62P+/CD61+ MVs concentration as well as percentage of total CD61+ in AnV+ population of MVs and time elapsed from IS in convalescent stroke subjects was revealed.

CONCLUSION

Our results confirm positive correlations between total pMV number, the number of PAC-1+/CD61+ and CD62+/CD61+ MVs and carotid atherosclerosis in stroke subjects. Some pMV parameters may exhibit a predictive value for the next VE in groups with a history of stroke. pMVs and some of their phenotypes decline over time elapsed from stroke in convalescent stroke subjects.

Potential role of platelets for atherosclerotic events in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease with increased risk of cardiovascular events and mortality that can be attributed to accelerated atherosclerosis. This pilot study aimed to investigate if changes in blood parameters were compatible with atherosclerotic events in RA patients. To this aim, 45 RA women (aged more than 18 years), and 25 age and gender-matched healthy donors (HD) were included. Biomarkers of oxidative stress, platelet activation and platelet aggregation were analysed in RA patients at baseline and after six months of treatment with disease modifying anti-rheumatic drugs (DMARDs). Flow cytometry analysis revealed that ca. 4% of platelets was in activated state (evaluated in term of Annexin V and PAC-1 positivity) in RA patients at baseline, and that the 76% of platelets displayed mitochondrial hyperpolarization. Moreover, platelets from RA patients at baseline aggregated more than those from HD after whole blood treatment with adenosine diphosphate. Interestingly, platelet aggregation in patients at baseline positively correlated with disease activity measured by DAS28 score. After six months of treatment with DMARDs, platelet activation and platelet aggregation reached values comparable to those of HD. Our preliminary data suggest that platelets might play an active role in the atherosclerosis occurring in RA patients.

TNFα expressed on the surface of microparticles modulates endothelial cell fate in rheumatoid arthritis

Background

Rheumatoid arthritis (RA) is associated with a high prevalence of atherosclerosis. Recently increased levels of microparticles (MPs) have been reported in patients with RA. MPs could represent a link between autoimmunity and endothelial dysfunction by expressing tumor necrosis factor alpha (TNFα), a key cytokine involved in the pathogenesis of RA, altering endothelial apoptosis and autophagy. The aim of this study was to investigate TNFα expression on MPs and its relationship with endothelial cell fate.

Methods

MPs were purified from peripheral blood from 20 healthy controls (HC) and from 20 patients with RA, before (time (T)0) and after (T4) 4-month treatment with etanercept (ETA). Surface expression of TNFα was performed by flow cytometry analysis. EA.hy926 cells, an immortalized endothelial cell line, were treated with RA-MPs purified at T0 and at T4 and also, with RA-MPs in vitro treated with ETA. Apoptosis and autophagy were then evaluated.

Results

RA-MPs purified at T0 expressed TNFα on their surface and this expression significantly decreased at T4. Moreover, at T0 RA-MPs, significantly increased both apoptosis and autophagy levels on endothelial cells, in a dose-dependent manner. RA-MPs did not significantly change these parameters after 4 months of in vivo treatment with ETA.

Conclusions

Our data demonstrate that MPs isolated from patients with RA exert a pathological effect on endothelial cells by TNFα expressed on their surface. In vivo and in vitro treatment with ETA modulates this effect, suggesting anti-TNF therapy protects against endothelial damage in patients with RA.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1768-8) contains supplementary material, which is available to authorized users.

Cleaved N-terminal histone tails distinguish between NADPH oxidase (NOX)-dependent and NOX-independent pathways of neutrophil extracellular trap formation

OBJECTIVES

Neutrophil extracellular traps (NETs) act in various rheumatic diseases. Although NET formation was originally described as a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX)-dependent pathway, it appears that there are also NOX-independent pathways of NET release. Currently, no tools are available that can discriminate between both NET-forming pathways. We aimed to develop a serological method allowing the discrimination between NETs generated through NOX-dependent or NOX-independent pathways.

METHODS

Histones from in vitro generated NOX-dependent and NOX-independent NETs were characterised with a panel of lupus-derived antibodies against N-terminal histone tails using immunofluorescence microscopy, western blot and ELISA. NETs in patients with NET-associated diseases, that is, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriatic arthritis (PsA) and sepsis, were characterised in sandwich ELISAs employing antibodies against myeloperoxidase (MPO) and N-terminal histone tails as detecting and capturing antibodies, respectively. Functional responses of endothelial cells to NOX-dependent and NOX-independent NETs were assessed as well.

RESULTS

Neutrophil elastase cleaves the N-terminal tails of core histones during NOX-dependent, but not during NOX-independent NET formation. Consequently, the detection of MPO-histone complexes with antibodies against N-terminal histone tails allows discrimination between NETs formed through a NOX-dependent or NOX-independent manner. Characterisation of in vivo circulating NETs revealed the presence of NOX-independent NETs in RA, SLE and sepsis, but NOX-dependent NETs in PsA. NOX-independent NETs displayed an increased capacity to activate endothelial cells when compared with NOX-dependent NETs.

CONCLUSIONS

These results indicate heterogeneity in NET-forming pathways in vivo and highlight the need for disease-specific strategies to prevent NET-mediated pathology.

Soluble CD40L is associated with increased oxidative burst and neutrophil extracellular trap release in Behçet's disease

Background

Studies have suggested that soluble factors in plasma from patients with active (aBD) and inactive (iBD) Behçet’s disease (BD) stimulate neutrophil function. Soluble CD40 ligand (sCD40L) is an important mediator of inflammation in BD. Its expression and effect on neutrophil oxidative burst and neutrophil extracellular trap (NET) release have not been characterized. In this study, we sought to investigate the role of plasma and the CD40L pathway on NET release and the oxidative burst profile in patients with aBD and iBD.

Methods

Neutrophils and peripheral blood mononuclear cells (PBMCs) were obtained from patients with aBD (n = 30), patients with iBD (n = 31), and healthy control subjects (HCs; n = 30). sCD40L plasma concentration was determined in individual samples. A pool of plasma for each group was created. In some experiments, plasma pools were treated with recombinant CD40 (rhCD40-muIg) for sCD40L blockade. NET release and H₂O₂/O₂⁻ production were determined after stimulation with phorbol 12-myristate 13-acetate, sCD40L, or plasma pool. Flow cytometric analysis was performed to evaluate the expression of (1) CD40, Mac-1, and phosphorylated NF-κB p65 on neutrophils and monocytes and (2) CD40L on activated T cells and platelets. CD40L gene expression in PBMCs was determined by qRT-PCR.

Results

sCD40L plasma levels were significantly higher in patients with iBD (median 17,234, range 2346–19,279 pg/ml) and patients with aBD (median 18,289, range 413–19,883 pg/ml) than in HCs (median 47.5, range 33.7–26.7 pg/ml; p < 0.001). NET release was constitutively increased in BD compared with HC. NET release and H₂O₂/O₂⁻ were higher after stimulation with sCD40L or BD plasma and decreased after sCD40L blockade. Mac-1 expression was constitutively increased in neutrophils of patients with aBD (88.7 ± 13.2% of cells) and patients with iBD (89.2 ± 20.1% of cells) compared with HC (27.1 ± 18.8% of cells; p < 0.01). CD40 expression on phagocytes and CD40L expression on platelets were similar in the three groups. PBMCs as well as nonactivated and activated CD4⁺ T cells from patients with BD showed higher CD40L expression.

Conclusions

Plasma from patients with aBD exerts a stimulus on NET release and oxidative burst, probably induced by sCD40L.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1443-5) contains supplementary material, which is available to authorized users.

Long-term Treatment with Anti-platelet Agents for Collagen-induced Arthritis Improves Radiological Findings

Objectives

The objectives of this study were to evaluate the long-term effect of anti-platelet treatment on the radiological progression of collagen-induced arthritis in rats.

Methods

Female Lewis rats with collagen-induced arthritis were divided into three experimental groups: saline, aspirin monotherapy (n = 12), and aspirin–clopidogrel dual therapy (n = 12). Drugs were administered daily and continued up to 70 days after the induction of arthritis. The clinical arthritis index (weight, morphology score, and paw thickness) and radiological scores were evaluated.

Results

The clinical arthritis index peaked on day 20, while the radiological scores peaked on day 35. No intergroup difference was observed in the clinical arthritis index throughout the experiment. The aspirin–clopidogrel dual therapy group had a significantly higher mean radiological score than the other groups (p = 0.045) on day 35. Further treatments resulted in significantly improved radiological findings in the aspirin monotherapy and aspirin–clopidogrel dual therapy groups on day 70 but no significant improvement in the saline group.

Conclusion

Anti-platelet agent treatment improved radiological findings on day 70. These observations emphasize the importance of a future long-term study of the effects of anti-platelet agent treatment on arthritis.

Association between mean platelet volume and disease severity in patients with psoriasis and psoriatic arthritis

Introduction

Mean platelet volume (MPV) is an important marker that shows the activation and function of the platelets, which is effective in the inflammatory diseases.

Aim

To show the relationship between MPV and the development of psoriatic arthritis (PA) in patients with psoriasis vulgaris (PV) and the correlation between MPV and psoriasis severity score (PASI).

Material and methods

Our study included 116 patients with psoriatic arthritis (68 female, 48 male) and 41 patients in the psoriasis group (19 female, 22 male) and 90 subjects in the control group (55 female, 35 male). The demographic data of the patients, duration of disease, PASI, the nature of the disease were evaluated retrospectively.

Results

Mean platelet volume levels of both the PV group (8.79 ±0.86 fl) and the PA group (9.18 ±1.26 fl) were significantly higher compared to the control group (8.42 ±0.74 fl). There was a weak statistically positive correlation between the PASI and the MPV according to the correlation analysis (r = 0.165; p = 0.046).

Conclusions

Our results show that MPV may be helpful as an indicator of the clinical course of PV and PA. In this regard, that study should be supported by prospective studies to find strong correlations.

The Inflammatory Role of Platelets: Translational Insights from Experimental Studies of Autoimmune Disorders

Beyond their indispensable role in hemostasis, platelets have shown to affect the development of inflammatory disorders, as they have been epidemiologically and mechanistically linked to diseases featuring an inflammatory reaction in inflammatory diseases like multiple sclerosis, rheumatoid arthritis and inflammatory bowel disorders. The identification of novel molecular mechanisms linking inflammation and to platelets has highlighted them as new targets for therapeutic interventions. In particular, genetic and pharmacological studies have identified an important role for platelets in neuroinflammation. This review summarizes the main molecular links between platelets and inflammation, focusing on immune regulatory factors, receptors, cellular targets and signaling pathways by which they can amplify inflammatory reactions and that make them potential therapeutic targets.

Anti-TNFα agents curb platelet activation in patients with rheumatoid arthritis

BACKGROUND

Cardiovascular disease is important in rheumatoid arthritis (RA). Tissue factor (TF) is expressed upon platelet activation and initiates coagulation. Anti-tumour necrosis factor-α (TNFα) agents seem to decrease RA-associated cardiovascular events. We investigated whether (1) TNFα activates human platelets and (2) TNFα pharmacological blockade modulates the platelet-leucocyte reciprocal activation in RA.

DESIGN

The expression of platelet TNFα receptors has been assessed by flow cytometry and immunogold electron microscopy. Platelet and leucocyte activation has been assessed also in the presence of antibodies against the TNFα receptors 1 and 2 and of infliximab. TF expression, binding to fibrinogen and phosphatidylserine exposure, has been assessed by flow cytometry, TF activity by coagulation time and by endogenous thrombin generation. Markers of platelet and leucocyte activation have been assessed in 161 subjects: 42 patients with RA, 12 with osteoarthritis, 37 age-matched and sex-matched patients with chronic stable angina and 70 age-matched and sex-matched healthy subjects.

RESULTS

TNFα elicited the platelet activation and the expression of TF, which in turn prompted thrombin generation and clot formation. Inhibition of the TNFα-induced activation restricted platelet ability to activate leucocytes and to induce leucocyte TF. TNFα inhibition did not influence platelet activation induced by collagen, ADP or thrombin receptor activating peptide-6. Platelets of patients with RA were more activated than those of controls. Activation was reduced in patients treated with TNFα inhibitors.

CONCLUSIONS

TNFα-dependent pathways control platelet activation and TF expression in RA. Further studies will verify whether the protective effect of TNFα inhibitors on cardiovascular events involves their ability to modulate platelet function.

Role of extracellular vesicles in autoimmune diseases

Extracellular vesicles (EVs) consist of exosomes released upon fusion of multivesicular bodies with the cell plasma membrane and microparticles shed directly from the cell membrane of many cell types. EVs can mediate cell-cell communication and are involved in many processes including inflammation, immune signaling, angiogenesis, stress response, senescence, proliferation, and cell differentiation. Accumulating evidence reveals that EVs act in the establishment, maintenance and modulation of autoimmune processes among several others involved in cancer and cardiovascular complications. EVs could also present biomedical applications, as disease biomarkers and therapeutic targets or agents for drug delivery.

Anti-citrullinated protein antibodies contribute to platelet activation in rheumatoid arthritis

Introduction

Although the role of platelets in rheumatoid arthritis (RA) is relatively unexplored, recent studies point towards a contribution of platelets in arthritis. We set out to determine platelet phenotype in RA and studied whether this could be influenced by the presence of anti-citrullinated protein antibodies (ACPA).

Methods

Platelets from healthy controls were incubated in the presence of plasma of patients with RA or age- and sex-matched healthy controls and plasma from ACPA^neg or ACPA^pos patients or in the presence of plate-bound ACPA. Characteristics of platelets isolated from patients with RA were correlated to disease activity.

Results

Platelets isolated from healthy controls displayed markers of platelet activation in the presence of plasma derived from RA patients, as determined by P-selectin expression, formation of aggregates and secretion of soluble CD40 ligand (sCD40L). Furthermore, levels of P-selectin expression and sCD40L release correlated with high ACPA titres. In accordance with these findings, enhanced platelet activation was observed after incubation with ACPA^pos plasma versus ACPA^neg plasma. Pre-incubation of platelets with blocking antibodies directed against low-affinity immunoglobulin G receptor (FcγRIIa) completely inhibited the ACPA-mediated activation. In addition, expression of P-selectin measured as number of platelets correlated with Disease Activity Score in 44 joints, C-reactive protein level, ACPA status and ACPA level.

Conclusions

We show for the first time that ACPA can mediate an FcγRIIa-dependent activation of platelets. As ACPA can be detected several years before RA disease onset and activated platelets contribute to vascular permeability, these data implicate a possible role for ACPA-mediated activation of platelets in arthritis onset.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0665-7) contains supplementary material, which is available to authorized users.

Evaluation of the efficacy and safety of different Tripterygium preparations on collagen-induced arthritis in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Tripterygium preparations (TPs), a traditional Chinese Medicines extracted from Tripterygium wilfordii Hook f., are widely used for treatment of rheumatoid arthritis (RA). However, TPs from different Pharmaceutical factory have different efficacy and side effects for RA treatment.

AIM OF THE STUDY

The purpose of the current study is to evaluate the efficacy and safety of four TPs from different Pharmaceutical factory in china on the treatment of collagen-induced arthritis (CIA) rats and provide a theoretical and experimental basis for the individualized use of TPs.

MATERIALS AND METHODS

The model of wistar rats of CIA was made, and the rats were perfused a stomach with four TPs for 3 weeks continuously. Then arthritis severity was determined by visual examination of the paws and histopathologic changes of joint, liver, kidney and testis were determined by hematoxylin-eosin (H&E) staining. The expression of inflammatory cytokines (IL-1β, TNF-α, IL-17 and IL-6) in the joint was analyzed by real-time PCR, and the count and motion parameters (sperm motility and progressive sperm) of sperm in cauda epididymis were assessed with computer-assisted sperm analysis (CASA) system. Routine blood tests were conducted using automated hematology analyzer, and the aspartate aminotransferase (AST), alanine aminotransferase (ALT) activities, creatinine (Cr), and blood urea nitrogen (BUN) in serum of CIA rats were measured using a UniCel DxC 880i autoanalyzer.

RESULTS

All of tested TPs could reduce inflammatory score, histopathological arthritis severity and joint׳s inflammatory cytokines (IL-1β, TNF-α, IL-17 and IL-6) expression in CIA rats, however, TP-D showed stronger inhibitory effect for inflammatory score compared with other three TPs in vivo. All of tested TPs did not show hepatotoxicity and nephrotoxicity and also had little effect for the concentration of hemoglobin (Hb) and the count of white blood cell (WBC). Analysis of red blood cell (RBC) number showed that TP-C and TP-D could reverse lower RBC number in untreated CIA rats to normal level. Interestingly, the results showed TPs named TP-C and TP-D could decrease platelet (PLT) number which significantly increases in untreated CIA rats. Reproductive toxicity, the main side effect of TPs, assay showed that the sperm quality (density, viability, and motility) in four of TPs-treated CIA rats were decreased significantly, consistently with spermatogenic cell density reduced. However parallel analysis showed that in four TPs-treated rats, the number of sperm, motile sperm and progressive sperm were highest in TP-D group, in contrast, were lowest in TP-C group.

CONCLUSIONS

These findings suggested that four TPs showed significantly therapeutic effect on ameliorating inflammation of CIA rats, with no obvious hepatotoxicity and nephrotoxicity in vivo. TP-D showed advantages with its higher efficacy and less reproductive toxicity as well as increasing RBC number, decreasing PLT number in CIA treatment. Thus, in the development of individualized treatment plan for RA patients, TP-D might be considered preferentially.

Platelets promote allergic asthma through the expression of CD154

Platelet activation is associated with multiple immune responses and the pathogenesis of various immune-related diseases. However, the exact role and the underlying mechanism of platelets in the progression of allergic asthma remain largely unclear. In this study, we demonstrate that during antigen sensitization, platelets can be activated by ovalbumin (OVA) aerosol via the upregulation of CD154 (CD40L) expression. Platelet transfer promoted allergic asthma progression by inducing more severe leukocyte infiltration and lung inflammation, elevated IgE production and strengthened T helper 2 (Th2) responses in asthma-induced mice. Accordingly, platelet depletion compromised allergic asthma progression. Cd154-deficient platelets failed to promote asthma development, indicating the requirement of CD154 for platelets to promote asthma progression. The mechanistic study showed that platelets inhibited the induction of Foxp3(+) regulatory T cells both in vivo and in vitro at least partially through CD154, providing an explanation for the increase of Th2 responses by platelet transfer. Our study reveals the previously unknown role of platelet CD154 in the promotion of asthma progression by polarizing Th2 responses and inhibiting regulatory T-cell generation and thus provides a potential clue for allergic disease interventions.

Platelets promote allergic asthma through the expression of CD154

Platelet activation is associated with multiple immune responses and the pathogenesis of various immune-related diseases. However, the exact role and the underlying mechanism of platelets in the progression of allergic asthma remain largely unclear. In this study, we demonstrate that during antigen sensitization, platelets can be activated by ovalbumin (OVA) aerosol via the upregulation of CD154 (CD40L) expression. Platelet transfer promoted allergic asthma progression by inducing more severe leukocyte infiltration and lung inflammation, elevated IgE production and strengthened T helper 2 (Th2) responses in asthma-induced mice. Accordingly, platelet depletion compromised allergic asthma progression. Cd154-deficient platelets failed to promote asthma development, indicating the requirement of CD154 for platelets to promote asthma progression. The mechanistic study showed that platelets inhibited the induction of Foxp3(+) regulatory T cells both in vivo and in vitro at least partially through CD154, providing an explanation for the increase of Th2 responses by platelet transfer. Our study reveals the previously unknown role of platelet CD154 in the promotion of asthma progression by polarizing Th2 responses and inhibiting regulatory T-cell generation and thus provides a potential clue for allergic disease interventions.

Are microparticles the missing link between thrombosis and autoimmune diseases? Involvement in selected rheumatologic diseases

Microparticles (MPs) are membrane-bound vesicles with important physiologic effects. MPs exchange information intercellularly, with each kind of MP carrying antigens and receptors of the cells from which they originated. They are biologic effectors in inflammation, angiogenesis, vascular injury, and thrombosis. Thrombosis is generally caused by abnormalities in blood flow, blood composition, and/or properties of the vessel wall. Thrombosis is a well-described feature of cardiovascular disease and cerebrovascular disease. Accumulating evidence suggests that increased risk of thrombosis is also characteristic of autoimmune disorders and immune-mediated diseases affecting all age groups, although the older adults are most vulnerable. Current research has also implicated MPs as a source of autoantigenic nuclear material that can form immune complexes, activate the innate immune system, and may lead to autoimmunity. This review focuses on the contribution of MPs to both the pathogenesis of autoimmune diseases and, as the immune and coagulation systems are tightly linked, their role in hypercoagulability in the setting of autoimmunity in an aging population.

Chronic arthritis and cardiovascular disease: altered blood parameters give rise to a prothrombotic propensity

OBJECTIVE

Rheumatoid arthritis, and to a lesser extent ankylosing spondylitis and psoriatic arthritis, associates with increased morbidity and mortality due to cardiovascular complications. We hypothesized that the increased risk of cardiovascular disease is reflected by changes in blood parameters that are compatible with a prothrombotic propensity. To substantiate this notion, we performed an extensive literature search identifying such parameters.

METHODS

A search through PubMed (1970-2013) was done to find primary articles with the following search terms: rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis or synovial fluid. These were combined with keywords reflecting processes of atherothrombosis: atherosclerosis, cardiovascular disease, coagulation, endothelial, fibrinolysis, mean platelet volume, microparticle, platelet, platelet count and mass, thrombosis, and thrombus.

RESULTS

The published studies point to a multitude of blood-related processes that can contribute to a prothrombotic propensity in chronic inflammatory diseases. These include an increase in platelet mass; low-level platelet activation, enforced by interaction with leukocytes and the formation of proinflammatory cytokines; a locally activated endothelium; and an increased coagulant activity. Patient treatment with methotrexate or TNF-α blockers appears to result in normalization of several of these prothrombotic parameters.

CONCLUSION

This analysis provides a first identification of the mechanisms by which inflammatory arthritis can aggravate cardiovascular disease.

Cardiovascular biomarkers in patients with psoriasis

Psoriasis is a systemic inflammatory disease of the skin with associated comorbidity. Severe forms of psoriasis are associated with increased mortality, which might be due to cardiovascular (CV) comorbidity. In this study, we investigated in 79 patients with psoriasis compared to 80 healthy volunteers different biomarkers that play a role in vascular disease and inflammation, such as C-reactive protein (CRP), human soluble CD40 ligand (sCD40L), oxidized low-density lipoprotein (ox-LDL), human matrix Gla protein (MGP) and fetuin-A. Our results showed that CRP (P < 0.0001), sCD40L (P < 0.0001) and MGP (P < 0.0001) were increased in the patient cohort. Fetuin-A showed decreased serum levels in patients with psoriasis (P < 0.0001), whereas ox-LDL did not show any significant difference. In multivariate analyses controlling for sex, age and BMI, these findings were confirmed. Thus, CV biomarkers are altered in patients with psoriasis. If the decrease in fetuin-A as well as the increase in sCD40L can be proven in further studies, these biomarkers may help to characterize a subgroup of patients who are at risk to develop CVD and/or monitor the effect of therapeutic antipsoriatic strategies on concomitant diseases. This knowledge may be useful in the management of high-need patients with psoriasis.

Lipid profile changes in patients with rheumatic diseases receiving a treatment with TNF-α blockers: a meta-analysis of prospective studies

BACKGROUND

Some studies showed an anti-atherogenic effect of TNF-α blockers on lipid profile, but these data have been challenged.

OBJECTIVE

To perform a meta-analysis on lipid profile changes induced by TNF-α blocker treatment.

METHODS

Prospective studies on rheumatic patients receiving TNF-α blockers and providing before-and-after treatment values of triglycerides (TGs), total cholesterol (TC), HDL-cholesterol (HDLc), LDL-cholesterol (LDLc), and atherogenic index (AI) were included. Standardized mean differences (SMD) in lipid profile were analyzed at short-term (2-12 weeks), middle-term (13-24 weeks), and long-term (25-52 weeks) assessments.

RESULTS

Thirty articles (1707 patients) were included. TNF-α blockers determined an increase in TC at short-term, middle-term, and long-term assessments (SMD: 0.20 mmol/L [95% CI: 0.04, 0.35]; SMD: 0.27 mmol/L [95% CI: 0.08, 0.46]; SMD: 0.22 mmol/L [95% CI: 0.01, 0.43]). HDLc increased only at the short-term assessment (SMD: 0.19 mmol/L [95% CI: 0.10, 0.28]), and TGs achieved a significant increase at the long-term assessment (SMD: 0.19 mmol/L [95% CI: 0.04, 0.34]). LDLc and AI were not affected by TNF-α blocker treatment.

CONCLUSIONS

Slight but significant increases in TC occurred without any significant change in LDLc and AI. Changes in HDLc and TGs were not consistent among the different time point assessments. These quantitative changes in lipid profile do not seem to be able to explain cardiovascular risk improvement reported in patients receiving TNF-α blockers. Further studies on other mechanisms are needed to address this issue.

Platelets and autoimmunity

Vascular injury is the initial manifestation of inflammation resulting in the recruitment and activation of various cell types. The integrity of the vascular wall is monitored by platelets that become activated in the presence of exposed subendothelium. Besides their well-established role in haemostasis, ample data are now emerging on the many immunoregulatory functions of platelets. Platelets store and release a large plethora of cytokines, chemokines and growth factors. They also represent the largest circulating pool of many inflammatory mediators like P-selectin, CD40L and non-neuronal serotonin. Furthermore, complement activation occurs on the platelet surface and deposition of complement results in platelet activation. Overall, platelets have multiple functions in both innate and adaptive immunity. Further insight into the multifaceted role of platelets could therefore provide important clues into how we could implement current platelet therapy to reduce both platelet-induced thrombosis and inflammation. In this review, we discuss the current perceptions of platelet involvement in various autoimmune diseases like rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis and multiple sclerosis.

CD154: the atherosclerotic risk factor in rheumatoid arthritis?

Atherosclerosis, now regarded as a chronic inflammatory disease of the arterial wall, and its clinical manifestations have increasingly been associated with rheumatoid arthritis (RA), supporting the notion that autoimmune diseases and vascular disorders share common etiological features. Indeed, evidence pertaining to this matter indicates that inflammation and its multiple components are the driving force behind the pathogenesis of these disorders. Interestingly, CD154 and its receptors have emerged as major players in the development of RA and atherosclerosis, which raises the possibility that this axis may represent an important biological link between both complications. Indeed, CD154 signaling elicits critical inflammatory responses that are common to the pathogenesis of both diseases. Here, we provide an overview of the traditional and disease-related interrelations between RA and vascular abnormalities, while focusing on CD154 as a potential mediator in the development of atherosclerotic events in RA patients.

Effects of xinfeng capsules on expression of platelet granule membrane protein 140 and platelet cluster of differentiation 40 ligand in peripheral blood of adjuvant arthritis rats

Platelet GMP-140 and CD40L as specific markers of platelet activation play an important role in the morbidity and development of rheumatoid arthritis. The expression of GMP-140, CD40L increases in peripheral blood of AA rats. And they have correlation with voix pedis' swelling, AI. XFC could inhibit the inflammatory response through inhibiting platelet activation of AA rats, which means decreasing the expression of GMP-140, CD40L in peripheral blood. So, the voix pedis' swelling and AI were decreased as the result.

Enhanced platelet-derived microparticle formation is associated with carotid atherosclerosis in convalescent stroke patients

Platelets participate in the development and progression of atherosclerosis. During this process they interact with endothelial cells and leukocytes. Therefore, we investigated the associations between carotid atherosclerosis and platelet reactivity markers. The platelet surface expression of P-selectin (CD62P) and the activated GPIIb/IIIa receptor (corresponding to increased binding of PAC-1), as well as the fraction of platelet-derived microparticles (PMPs) prior to and after platelet stimulation with TRAP or ADP, were determined using flow cytometry in 94 subjects in the convalescent phase of ischaemic stroke and in 76 disease controls. The mean common carotid intima-media thickness (CCA(mean) IMT), maximal common carotid IMT (CCA(max) IMT) and maximal bifurcation IMT (BIF(max) IMT) were measured bilaterally using B mode, colour Doppler ultrasonography. In stroke subjects IMT within CCA and BIF were greater than in disease controls and the percentage of PMPs prior to and after ex vivo stimulation with agonists was significantly higher than in controls. Multiple regression analysis revealed that PMPs were positively and independently correlated with both CCA(mean) IMT (β = 0.23; p < 0.01) and stroke (β = 0.21; p<0.01), while PAC-1 binding to platelets activated with ADP was negatively and independently associated with CCA(mean) IMT (β = -0.29; p<0.001) and atherosclerotic carotid plaque presence (β = -0.28, p = 0.003). We found a positive association between enhanced PMP formation and atherosclerotic thickening of carotid intima-media or carotid plaque in patients after ischaemic stroke. We demonstrated that diminished expression of active GPIIb/IIIa in the ADP-activated platelets is associated with increased carotid IMT, independently of stroke.

Selectins and Associated Adhesion Proteins in Inflammatory disorders

Inflammation is defined as the normal response of living tissue to injury or infection. It is important to emphasize two components of this definition. First, that inflammation is a normal response and, as such, is expected to occur when tissue is damaged. Infact, if injured tissue does not exhibit signs of inflammation this would be considered abnormal and wounds and infections would never heal without inflammation. Secondly, inflammation occurs in living tissue, hence there is need for an adequate blood supply to the tissues in order to exhibit an inflammatory response. The inflammatory response may be triggered by mechanical injury, chemical toxins, and invasion by microorganisms, and hypersensitivity reactions. Three major events occur during the inflammatory response: the blood supply to the affected area is increased substantially, capillary permeability is increased, and leucocytes migrate from the capillary vessels into the surrounding interstitial spaces to the site of inflammation or injury. The inflammatory response represents a complex biological and biochemical process involving cells of the immune system and a plethora of biological mediators. Cell-to-cell communication molecules such as cytokines play an extremely important role in mediating the process of inflammation. Inflammation and platelet activation are critical phenomena in the setting of acute coronary syndromes. An extensive exposition of this complex phenomenon is beyond the scope of this article (Rankin 2004).

The CD40-CD40L system in cardiovascular disease

The CD40-CD40L system is a pathway which is associated with both prothrombotic and proinflammatory effects. CD40 and its ligand were first discovered on the surface of activated T cells, but its presence on B cells, antigen-presenting cells, mast cells, and finally platelets, is evident. The soluble form of CD40L (sCD40L) is derived mainly from activated platelets and contributes to the pathophysiology of atherosclerosis and atherothrombosis. Indeed, sCD40L has autocrine, paracrine, and endocrine activities, and it enhances platelet activation, aggregation, and platelet-leucocyte conjugation that may lead to atherothrombosis. It has even been suggested that sCD40L may play a pathogenic role in triggering acute coronary syndromes. Conversely, blockade of this pathway with anti-CD40L antibodies may prevent or delay the progression of atherosclerosis. Concentrations of sCD40L also predict risk of future cardiovascular disease in healthy women and clinical outcomes in patients with acute coronary syndromes. However, there are controversial and uncertain points over the application of this biomarker to clinical cardiology. In this review, we provide an overview of potential implications of CD40-CD40L signalling and sCD40L as a biomarker in patients with atherosclerotic vascular diseases.

Platelet function in rheumatoid arthritis: arthritic and cardiovascular implications

Patients with rheumatoid arthritis (RA) are at high risk of cardiovascular events. Platelet biomarkers are involved in inflammation, atherosclerosis and thrombosis. Cardiovascular and RA-associated factors can alter the structure and function of platelets, starting from megakaryocytopoiesis. Reactive megakaryocytopoiesis increases circulating platelets count and triggers hyperactivity. Hyperactive platelets target synovial membranes with subsequent local rheumatoid inflammation. Hyperactive platelets interact with other cells, and target the vascular wall. Accumulating evidence suggests that disease modifying anti-rheumatic drugs (DMARD) decrease platelet activity.

Platelet function in rheumatoid arthritis: arthritic and cardiovascular implications

Patients with rheumatoid arthritis (RA) are at high risk of cardiovascular events. Platelet biomarkers are involved in inflammation, atherosclerosis and thrombosis. Cardiovascular and RA-associated factors can alter the structure and function of platelets, starting from megakaryocytopoiesis. Reactive megakaryocytopoiesis increases circulating platelets count and triggers hyperactivity. Hyperactive platelets target synovial membranes with subsequent local rheumatoid inflammation. Hyperactive platelets interact with other cells, and target the vascular wall. Accumulating evidence suggests that disease modifying anti-rheumatic drugs (DMARD) decrease platelet activity.

Thrombin generation in rheumatoid arthritis: dependence on plasma factor composition

Growing evidence indicates that rheumatoid arthritis (RA) is associated with an increased risk for thromboembolic cardiovascular events. We investigated thrombin generation profiles in RA patients and their dependence on plasma factor/inhibitor composition. Plasma factor (F) compositions (II, V, VII, VIII, IX, X), antithrombin and free tissue factor pathway inhibitor (TFPI) from 46 consecutive RA patients with no cardiovascular events (39 female, 7 male, aged 57 [range, 23-75] years; DAS28 [Disease Activity Score] 5.2 +/- 1.1) were compared with those obtained in age- and sex-matched apparently healthy controls. Using each individual's plasma coagulation protein composition, tissue factor-initiated thrombin generation was assessed both computationally and empirically. RA patients had higher fibrinogen (4.18 [IQR 1.09] vs. 2.56 [0.41] g/l, p<0.0001), FVIII (226 +/- 40 vs. 113 +/- 15%, p<0.001), PC (107 [16] vs. 100 [14]%, p<0.001), and free TFPI levels (22.3 [2.2] vs. 14.7 [2.1] ng/ml, p<0.001). DAS28, but not age, RA duration, or C-reactive protein, was associated with FV, FVIII, FIX, FX, antithrombin, and free TFPI (r from 0.27 to 0.48, p<0.05). Intergroup comparison of computational thrombin generation profiles showed that in RA patients, maximum thrombin levels (p=0.01) and the rate of thrombin formation (p<0.0001) were higher, whereas the initiation phase of thrombin generation (p<0.0001) and the time to maximum thrombin levels (p<0.0001) were longer. Empirical reconstructions of the populations reproduced the thrombin generation profiles generated by the computational model. Simulations of thrombin formation suggest that blood plasma composition, i.e. a marked increase in FVIII, somewhat counterbalanced by free TFPI, contributes to the prothrombotic phenotype in RA patients.

Preliminary evidence for a matrix metalloproteinase-2 (MMP-2)-dependent shedding of soluble CD40 ligand (sCD40L) from activated platelets

Platelets are the major source of soluble CD40 ligand (sCD40L) in the blood. It has been demonstrated that CD40L is cleaved from the surface of activated platelets to release sCD40L. However, the enzyme involved in sCD40L shedding has not been identified yet. Using a panel of pharmacological inhibitors of serine, cysteine, aspartate, or metalloproteinases, preliminary evidence is presented for the hypothesis that matrix metalloproteinase-2 (MMP-2) might be the protease, primarily responsible for CD40L cleavage from platelet surface.