[Microparticles during sepsis and trauma. A link between inflammation and thrombotic processes]

Physiological role of reactive oxygen species as promoters of natural defenses

It has been 60 yr since the discovery of reactive oxygen species (ROS) in biology and the beginning of the scientific community's attempt to understand the impact of the unpaired electron of ROS molecules in biological pathways, which was eventually noted to be toxic. Several studies have shown that the presence of ROS is essential in triggering or acting as a secondary factor for numerous pathologies, including metabolic and genetic diseases; however, it was demonstrated that chronic treatment with antioxidants failed to show efficacy and positive effects in the prevention of diseases or health complications that result from oxidative stress. On the contrary, such treatment has been shown to sometimes even worsen the disease. Because of the permanent presence of ROS in organisms, elaborate mechanisms to adapt with these reactive molecules and to use them without necessarily blocking or preventing their actions have been studied. There is now a large body of evidence that shows that living organisms have conformed to the presence of ROS and, in retrospect, have adapted to the bioactive molecules that are generated by ROS on proteins, lipids, and DNA. In addition, ROS have undergone a shift from being molecules that invoked oxidative damage in regulating signaling pathways that impinged on normal physiological and redox responses. Working in this direction, this review unlocks a new conception about the involvement of cellular oxidants in the maintenance of redox homeostasis in redox regulation of normal physiological functions, and an explanation for its essential role in numerous pathophysiological states is noted.-Roy, J., Galano, J.-M., Durand, T., Le Guennec, J.-Y., Lee, J. C.-Y. Physiological role of reactive oxygen species as promoters of natural defenses.

Microparticles in Chronic Heart Failure

Heart failure (HF) continues to have a sufficient impact on morbidity, mortality, and disability in developed countries. Growing evidence supports the hypothesis that microparticles (MPs) might contribute to the pathogenesis of the HF development playing a pivotal role in the regulation of the endogenous repair system, thrombosis, coagulation, inflammation, immunity, and metabolic memory phenomenon. Therefore, there is a large body of data clarifying the predictive value of MP numerous in circulation among subjects with HF. Although the determination of MP signature is better than measurement of single MP circulating level, there is not yet close confirmation that immune phenotype of cells produced MPs are important for HF prediction and development. The aim of the chapter is to summarize knowledge regarding the role of various MPs in diagnosis and prognosis of HF. The role of MPs as a delivery vehicle for drugs attenuated cardiac remodeling is considered.

Microparticles: new light shed on the understanding of venous thromboembolism

Microparticles are small membrane fragments shed primarily from blood and endothelial cells during either activation or apoptosis. There is mounting evidence suggesting that microparticles perform a large array of biological functions and contribute to various diseases. Of these disease processes, a significant link has been established between microparticles and venous thromboembolism. Advances in research on the role of microparticles in thrombosis have yielded crucial insights into possible mechanisms, diagnoses and therapeutic targets of venous thromboembolism. In this review, we discuss the definition and properties of microparticles and venous thromboembolism, provide a synopsis of the evidence detailing the contributions of microparticles to venous thromboembolism, and propose potential mechanisms, by which venous thromboembolism occurs. Moreover, we illustrate a possible role of microparticles in cancer-related venous thromboembolism.

Endothelial, platelet, and tissue factor-bearing microparticles in cancer patients with and without venous thromboembolism

BACKGROUND

Cancer is a prothrombotic state, with an increased prevalence of venous thromboembolism (VTE). Microparticles (MPs) are sub-micron-sized vesicles derived from activated or apoptotic cells that may play a role in VTE, although evidence of this association is still limited.

OBJECTIVES

To evaluate the hypothesis that elevated numbers of endothelial (EMPs), platelets (PMPs), and Tissue Factor-bearing MPs (TF(+)MPs) in plasma may contribute to cancer-associated thrombosis.

PATIENTS/METHODS

EMPs, PMPs and TF(+)MPs plasma levels were measured in 90 consecutive patients (cases) referred to our Department (30 with a first episode of unprovoked VTE; 30 with active cancer; 30 with a diagnosis of acute VTE associated with active cancer), and in a group of 90 healthy subjects (controls). MPs analyses were performed by flow-cytometry (Cytomics FC500).

RESULTS

Cases showed statistically significant higher (mean ± SD) circulating EMPs and PMPs plasma levels (920 ± 341 and 1221 ± 413 MP/μL, respectively) than controls (299 ± 102 and 495 ± 241 MP/μL; p<0.005). Moreover cancer patients (with and without VTE) showed higher (mean ± SD) TF(+)MPs (927 ± 415 MPs/μL) than controls (204 ± 112 MPs/μL; p<0.001). The subgroup of cancer patients plus VTE showed statistically significant higher TF(+)MPs plasma levels (1019 ± 656 MPs/μL) than cancer patients without VTE (755 ± 391 MPs/μL, p = 0.002). Multivariate analysis failed to show a significant association between elevated TF(+)MPs and VTE in cancer patients.

CONCLUSIONS

Our results suggest that MPs might be an important intermediate in the cascade of cellular injury and vascular dysfunctions underlying the process of thrombosis, particularly in cancer. Further clinical investigations are needed to confirm the precise role of MPs in predicting hypercoagulable state in patients with cancer.

Microparticle-induced release of B-lymphocyte regulators by rheumatoid synoviocytes

Introduction

In the present study, we investigated the ability of microparticles isolated from synovial fluids from patients with rheumatoid arthritis or osteoarthritis to induce the synthesis and release of key cytokines of B-lymphocyte modulation such as B cell-activating factor, thymic stroma lymphopoietin, and secretory leukocyte protease inhibitor by rheumatoid fibroblast-like synoviocytes.

Methods

Microparticles were analyzed in synovial fluids from patients with rheumatoid arthritis, osteoarthritis, microcristalline arthritis, and reactive arthritis. In addition, microparticle release after activation from various cell lines (CEM lymphocyte and THP-1 cells) was assessed. Microparticles were isolated by differential centrifugation, and quantitative determinations were carried out by prothrombinase assay after capture on immobilized annexin V. B cell-activating factor, thymic stroma lymphopoietin, and secretory leukocyte protease inhibitor release was evaluated by enzyme-linked immunosorbent assay.

Results

Microparticles isolated from synovial fluids obtained from rheumatoid arthritis and osteoarthritis patients or microparticles derived from activated THP-1 cells were able to induce B cell-activating factor, thymic stroma lymphopoietin, and secretory leukocyte protease inhibitor release by rheumatoid arthritis fibroblast-like synoviocytes. Conversely, CEM-lymphocytes-derived microparticles generated by treatment with a combination of PHA, PMA and Adt-D did not promote the release of B cell-activating factor but favored the secretion of thymic stroma lymphopoietin and secretory leukocyte protease inhibitor by rheumatoid arthritis fibrobast-like synoviocytes. However, microparticles isolated from actinomycin D-treated CEM lymphocytes were not able to induce B cell-activating factor, thymic stroma lymphopoietin, or secretory leukocyte protease inhibitor release, indicating that microparticles derived from apoptotic T cells do not function as effectors in B-cell activation.

Conclusions

These results demonstrate that microparticles are signalling structures that may act as specific conveyors in the triggered induction and amplification of autoimmunity. This study also indicates that microparticles have differential effects in the crosstalk between B lymphocytes and target cells of autoimmunity regarding the parental cells from which they derive.

[Acute traumatic haemorrhagic shock and transfusion: what's new in 2009?]

In spite of continuous progress in surgery and in interventional radiology, massive haemorrhage remains a leading cause of death in traumatology. The transfusional strategy appears a key step in the treatment of haemorrhagic shock. In the light of new insights into the pathophysiology of coagulopathies associated with traumatic shock it seems reasonable to transfuse patients with haemorrhagic shock earlier than previously recommended.

Effects of anticoagulant strategies on activation of inflammation and coagulation

Acute inflammatory events, such as those that occur in sepsis, lead to dysregulation of the coagulation cascade. The hemostatic imbalance in sepsis, characterized by the excessive activation of procoagulant pathways and the impairment of anticoagulant activity, leads to disseminated intravascular coagulation and results in microvascular thrombosis, tissue hypoperfusion and, ultimately, multiple organ failure and death. Furthermore, natural anti-inflammatory mechanisms of the endogenous anticoagulants are diminished by the impaired coagulation. Supportive strategies aiming at inhibiting activation of coagulation and inflammation by treatment with exogenous anticoagulants have been found to be beneficial in experimental and initial clinical studies. This review summarizes the available experimental and clinical data regarding the interaction between coagulation and inflammation, focusing on the two anticoagulants which are in clinical use, antithrombin and activated protein C. Identification of the different biological mechanisms of the two endogenous anticoagulants might help to determine target patient populations as well as to develop new anticoagulant analogs that differ in there respective effects in coagulation and inflammation.