Antonella Capozzi

Bio: Antonella Capozzi is an academic researcher from Sapienza University of Rome. The author has contributed to research in topics: Antiphospholipid syndrome & Signal transduction. The author has an hindex of 16, co-authored 51 publications receiving 959 citations.

Anti-β2-glycoprotein I antibodies induce monocyte release of tumor necrosis factor α and tissue factor by signal transduction pathways involving lipid rafts

Abstract: Objective To investigate the association of β2-glycoprotein I (β2GPI) with lipid rafts in monocytic cells and to evaluate the proinflammatory and procoagulant effects of anti-β2GPI binding to its target antigen on the monocyte plasma membrane. Methods Human monocytes were fractionated by sucrose density-gradient centrifugation and analyzed by Western blotting. Immunoprecipitation experiments were performed to analyze the association of β2GPI with lipid rafts and the possible interaction of β2GPI with annexin A2 and Toll-like receptor 4 (TLR-4). Monocytes were then stimulated with affinity-purified anti-β2GPI antibodies from patients with the antiphospholipid syndrome (APS). Interleukin-1 receptor–associated kinase (IRAK) phosphorylation and NF-κB activation were evaluated by immunoprecipitation and transcription factor assay, respectively. Supernatants from monocytes were tested for tumor necrosis factor α (TNFα) and tissue factor (TF) levels by enzyme-linked immunosorbent assay. Results We found β2GPI and its putative receptor annexin A2 in lipid raft fractions of human monocytes. Moreover, there was an association between β2GPI and TLR-4, suggesting that it was partially dependent on raft integrity. Triggering with anti-β2GPI antibodies induced IRAK phosphorylation and consequent NF-κB activation, which led to the release of TNFα and TF. Conclusion Anti-β2GPI antibodies react with their target antigen, likely in association with annexin A2 and TLR-4, in lipid rafts in the monocyte plasma membrane. Anti-β2GPI binding triggers IRAK phosphorylation and NF-κB translocation, leading to a proinflammatory and procoagulant monocyte phenotype characterized by the release of TNFα and TF, respectively. These findings provide new insight into the pathogenesis of APS, improving our knowledge of valuable therapeutic targets.

Autophagy generates citrullinated peptides in human synoviocytes: a possible trigger for anti-citrullinated peptide antibodies

Abstract: Objectives Autophagy may represent a functional processing event that creates a substrate for autoreactivity. In particular, autophagy may play a role in the pathogenesis of RA, since autophagy is a key cellular event involved in the generation of citrullinated peptides, with consequent breakage of tolerance. Thus, in RA, autophagy may be the common feature in several situations (including smoking, joint injury and infection) that may drive the adaptive responses to citrullinated self-proteins. The aim of this study was the analysis, in vitro, of the role of autophagy in the generation of citrullinated peptides and, in vivo, of the relationship between autophagy and the production of anti-CCP antibodies (Abs). Methods For autophagy induction, fibroblast-like synoviocytes, primary fibroblasts and monocytes were stimulated with tunicamycin or rapamycin. Peptidyl arginine deiminase activity was tested by enzyme-linked immunosorbent assay, and protein citrullination was evaluated by western blotting. The main citrullinated RA candidate antigens, vimentin, α-enolase and filaggrin, were demonstrated by immunoprecipitation. The relationship between autophagy and anti-CCP Abs was analysed in 30 early-active RA patients. Results Our results demonstrated in vitro a role for autophagy in the citrullination process. Cells treated with tunicamycin or rapamycin showed peptidyl arginine deiminase 4 activation, with consequent protein citrullination. Immunoblotting and immunoprecipitation experiments, using specific Abs, identified the main citrullinated proteins: vimentin, α-enolase and filaggrin. In vivo, a significant association between levels of autophagy and anti-CCP Abs was observed in treatment-naive early-active RA patients. Conclusion These findings support the view that the processing of proteins in autophagy generates citrullinated peptides recognized by the immune system in RA.

The Pathogenesis of the Antiphospholipid Syndrome

Abstract: The antiphospholipid syndrome is a prothrombotic disorder associated with autoantibodies. It is associated with obstetrical complications (mainly spontaneous abortion) as well as venous and arterial thrombotic risks. Insights into disease mechanisms have led to new therapies.

Redox status expressed as GSH:GSSG ratio as a marker for oxidative stress in paediatric tumour patients.

Abstract: Oxidative stress causes profound alterations of various biological structures, including cellular membranes, lipids, proteins and nucleic acids, and it is involved in numerous malignancies. Reduced glutathione (GSH) is considered to be one of the most important scavengers of reactive oxygen species (ROS), and its ratio with oxidised glutathione (GSSG) may be used as a marker of oxidative stress. The main aim of this study was to determine GSH:GSSG ratio in the blood serum of paediatric cancer patients to use this ratio as a potential marker of oxidative stress. The whole procedure was optimised and the recoveries for both substances were greater than 80% under the optimised conditions. We analysed a group of paediatric patients (n=116) with various types of cancer, including neuroblastoma, anaplastic ependymoma, germ cell tumour, genital tract tumour, lymphadenopathy, rhabdomyosarcoma, nephroblastoma, Ewing's sarcoma, osteosarcoma, Hodgkin's lymphoma, medulloblastoma and retinoblastoma. We simultaneously determined the levels of reduced and oxidised glutathione, and thus, its ratio in the blood serum of the patients. The highest ratio was observed in retinoblastoma patients and the lowest in anaplastic ependymoma. We were able to distinguish between the diagnoses based on the results of the obtained GSH:GSSG ratio.

Tissue Factor: An Essential Mediator of Hemostasis and Trigger of Thrombosis.

Abstract: Tissue factor (TF) is the high-affinity receptor and cofactor for factor (F)VII/VIIa The TF-FVIIa complex is the primary initiator of blood coagulation and plays an essential role in hemostasis TF is expressed on perivascular cells and epithelial cells at organ and body surfaces where it forms a hemostatic barrier TF also provides additional hemostatic protection to vital organs, such as the brain, lung, and heart Under pathological conditions, TF can trigger both arterial and venous thrombosis For instance, atherosclerotic plaques contain high levels of TF on macrophage foam cells and microvesicles that drives thrombus formation after plaque rupture In sepsis, inducible TF expression on monocytes leads to disseminated intravascular coagulation In cancer patients, tumors release TF-positive microvesicles into the circulation that may contribute to venous thrombosis TF also has nonhemostatic roles For instance, TF-dependent activation of the coagulation cascade generates coagulation proteases, such as FVIIa, FXa, and thrombin, which induce signaling in a variety of cells by cleavage of protease-activated receptors This review will focus on the roles of TF in protective hemostasis and pathological thrombosis