Biomedical subjects

Felice D'Agnillo

Publications and source records attributed to Felice D'Agnillo.

5 recordsLinked to original sources

PubMed2005

Anthrax lethal toxin enhances cytokine-induced VCAM-1 expression on human endothelial cells.

Vascular endothelial dysfunction is thought to play a prominent role in systemic anthrax pathogenesis. We examined the effect of anthrax lethal toxin (LTx), a key virulence factor of Bacillus anthracis, on the expression of vascular cell adhesion molecule-1 (VCAM-1) on normal and cytokine-stimulated human lung microvascular endothelial cells. Confluent endothelial monolayers were treated with lethal factor (LF), protective antigen (PA), or both (LTx) in the presence or absence of tumor necrosis factor-alpha (TNFalpha). LTx enhanced cytokine-induced VCAM-1 expression and monocyte adhesion. LTx alone had no effect on VCAM-1 expression. LF, PA or the combination of a catalytically inactive mutant LF and PA failed to enhance cytokine-induced VCAM-1 expression. Treatment with inhibitors of mitogen-activated protein kinase kinases (MEKs) and mitogen-activated protein kinases did not reproduce the VCAM-1 enhancement effect of LTx, a known MEK metalloprotease, suggesting LTx-mediated MEK cleavage may not be a contributing factor.

Antigens, Bacterial↗

PubMed2005

Anthrax lethal toxin induces endothelial barrier dysfunction.

Hemorrhage and pleural effusion are prominent pathological features of systemic anthrax infection. We examined the effect of anthrax lethal toxin (LT), a major virulence factor of Bacillus anthracis, on the barrier function of primary human lung microvascular endothelial cells. We also examined the distribution patterns of cytoskeletal actin and vascular endothelial-cadherin (VE-cadherin), both of which are involved in barrier function regulation. Endothelial monolayers cultured on porous membrane inserts were treated with the LT components lethal factor (LF) and protective antigen (PA) individually, or in combination. LT induced a concentration- and time-dependent decrease in transendothelial electrical resistance that correlated with increased permeability to fluorescently labeled albumin. LT also produced a marked increase in central actin stress fibers and significantly altered VE-cadherin distribution as revealed by immunofluorescence microscopy and cell surface enzyme-linked immunosorbent assay. Treatment with LF, PA, or the combination of an inactive LF mutant and PA did not alter barrier function or the distribution of actin or VE-cadherin. LT-induced barrier dysfunction was not dependent on endothelial apoptosis or necrosis. The present findings support a possible role for LT-induced barrier dysfunction in the vascular permeability changes accompanying systemic anthrax infection.

Antigens, Bacterial↗

PubMed2004

Redox active hemoglobin enhances lipopolysaccharide-induced injury to cultured bovine endothelial cells.

The interaction of cell-free hemoglobin with lipopolysaccharide (LPS) is thought to aggravate the pathophysiology of sepsis and/or septic shock. This study examines the possible modulatory role of cell-free hemoglobin on LPS-induced apoptosis of cultured bovine aortic endothelial cells. Experiments were performed with or without fetal bovine serum, a source of LPS-binding protein and soluble CD14. In the absence of serum, LPS alone or coincubated with purified bovine hemoglobin (BvHb), human hemoglobin (Hb), or alpha-cross-linked Hb (alphaalphaHb) did not induce apoptosis. In the presence of serum, LPS induced significant apoptosis. LPS combined with BvHb, Hb, or alphaalphaHb produced the same extent of apoptosis as LPS alone. To examine whether the H(2)O(2)-driven redox activity of hemoglobin alters LPS-induced apoptosis, glucose oxidase was added to the system to generate a subtoxic flux of H(2)O(2). The combined treatment of LPS, glucose oxidase, and BvHb, Hb, or alphaalphaHb enhanced apoptosis compared with LPS alone. These findings support a possible mechanism whereby the redox cycling of hemoglobin, and not its direct interaction with LPS, contributes to the hemoglobin-mediated enhancement of LPS-related pathophysiology.

Animals↗

PubMed2002

A role for the myoglobin redox cycle in the induction of endothelial cell apoptosis.

This study investigates the potential role of the ferric/ferryl redox cycle of myoglobin (Mb) in the development of endothelial cell injury. Bovine aortic endothelial cells were incubated with ferric Mb (0.5-100 micro M) in the presence or absence of low steady states of H(2)O(2) (3-4 micro M) generated by glucose oxidase (GOX). The reaction of ferric Mb with H(2)O(2) generated ferryl Mb as monitored spectrophotometrically. Ferryl Mb formation correlated with the induction of apoptosis as indicated by morphological criteria, caspase 3 activation, phosphatidylserine (PS) externalization, and nuclear condensation by Hoechst 33342 staining. The addition of ascorbate or catalase inhibited the formation of ferryl Mb and the onset of apoptosis, whereas apoptosis was enhanced in cells depleted of intracellular glutathione by pretreatment with buthionine sulfoximine. Mb and Mb/GOX suppressed cell cycle progression, but only Mb/GOX produced significant cell loss revealed by the accumulation of sub G1 events. These results suggest a role for the Mb redox cycle in the induction of endothelial cell apoptosis, which may be relevant in the pathophysiology of diseases characterized by the release of Mb from damaged muscle.

Animals↗

PubMed2002

Cellular prion protein is expressed on endothelial cells and is released during apoptosis on membrane microparticles found in human plasma.

BACKGROUND: Blood and plasma of animals experimentally infected with transmissible spongiform encephalopathies (TSEs) can transmit TSE infection by transfusion. A conformational isoform of prion protein (PrPsc) is believed to be the TSE-infectious agent that propagates by converting the cellular prion protein (PrPc) to additional molecules of PrPsc. In orally infected animals, PrPsc accumulates in intestinal endothelial cells. In blood, two thirds of PrPc resides in plasma, but its source is not known. STUDY DESIGN AND METHODS: The expression of PrPc in cultured human umbilical vein endothelial cells (HUVECs) was studied using flow cytometry, immunoblotting, and RT-PCR. Flow cytometry was used to characterize endothelial membrane microparticles (MPs) in cell culture supernatants and in normal human plasma. RESULTS: HUVECs and bovine aorta endothelial cells express PrPc. The number of surface PrPc molecules per cell in HUVECs was 58,000 +/- 2,800. The induction of apoptosis in HUVECs led to a marked release of membrane MPs (60,000-80,000 MPs/10(3) cells) that expressed PrPc and other endothelial antigens. The presence of endothelial cell-derived MPs expressing PrPc was demonstrated in platelet-free human plasma. CONCLUSION: Endothelial cell apoptosis is associated with the release of PrPc-positive MPs. These MPs contribute to the PrPc pool in plasma and may have a role in disseminating TSE infectivity in blood.

Animals↗