Chiara Foglieni

Chromogranin A protects vessels against tumor necrosis factor alpha-induced vascular leakage

Elevated levels of circulating chromogranin A (CgA), a protein stored in the secretory granules of many neuroendocrine cells and neurons, have been detected in the blood of patients with neuroendocrine tumors or heart failure. The pathophysiological role of increased secretion of CgA is unknown. Using mice bearing subcutaneous tumors genetically engineered to secrete CgA in circulation, we have found that increased blood levels of this protein prevent vascular leakage induced by tumor necrosis factor‐α (TNF) in the liver venous system. Structure–activity studies, carried out with CgA fragments administered to normal mice, showed that an active site is located within residues 7–57 of CgA. Accordingly, an anti‐CgA antibody directed to residues 53–57 inhibited the effect of circulating CgA, either endogenously produced or exogenously administered, on liver vessels. Studies of the mechanism of action showed that CgA inhibits TNF‐induced VE‐cadherin down‐regulation and barrier alteration of cultured endothelial cells, in an indirect manner. Other effectors, such as thrombin and vascular endothelial growth factor were partially inhibited by CgA N‐terminal fragments in in vitro permeability assays. These findings suggest that circulating CgA could help regulate the endothelial barrier function and to protect vessels against TNF‐induced plasma leakage in pathological conditions characterized by increased production of TNF and CgA, such as cancer or heart failure.

The vasostatin-I fragment of chromogranin A inhibits VEGF-induced endothelial cell proliferation and migration

A growing body of evidence suggests that chromogranin A (CgA), a secretory protein released by many neuroendocrine cells and frequently used as a diagnostic and prognostic serum marker for a range of neuroendocrine tumors, is a precursor of several bioactive fragments. This work was undertaken to assess whether the N‐terminal fragment CgA1–76 (called vasostatin I) can inhibit the proangiogenic activity of vascular endothelial growth factor (VEGF), a factor involved in tumor growth. The effect of recom‐binant human vasostatin I (VS‐1) on VEGF‐induced human umbilical endothelial cells (HUVEC) signaling, proliferation, migration, and organization has been investigated. We have found that VS‐1 (3 μg/ml;330 nM) can inhibit VEGF‐induced ERK phosphorylation, as well as cell migration, proliferation, morphogenesis, and invasion of collagen gels in various in vitro assays. In addition, VS‐1 could inhibit the formation of capillary‐like structures in Matrigel plugs in a rat model. VS‐1 could also inhibit basal ERK phosphorylation and motility of HUVEC, leading to a more quiescent state in the absence of VEGF, without inducing apoptotic or necrotic effects. Conclusion: These findings suggest that vasostatin I may play a novel role as a regulator of endothelial cell function and homeostasis.—Belloni, D., Scabini, S., Foglieni, C., Veschini, L., Giazzon, A., Colombo, B., Fulgenzi, A., Helle, K. B., Ferrero, M. E., Corti, A., Ferrero, E. The vasostatin‐I fragment of chromogranin A inhibits VEGF‐induced endothelial cell proliferation and migration. FASEB J. 21, 3052–3062 (2007)

Increased expression and secretion of resistin in epicardial adipose tissue of patients with acute coronary syndrome

The purpose of this study was to test the hypothesis that specific epicardial adipose tissue (EAT) proinflammatory adipokines might be implicated in acute coronary syndrome (ACS). We compared expression and protein secretion of several EAT adipokines of male ACS with those of matched stable coronary artery disease (CAD) patients and controls with angiographically normal coronary arteries. The effect of supernatant of cultured EAT on endothelial cell permeability in vitro was also evaluated in the three study groups. EAT of ACS patients showed significantly higher gene expression and protein secretion of resistin than patients with stable CAD. Interleukin-6, plasminogen activator inhibitor-1, and monocyte chemoattractant protein-1 genes were also significantly overexpressed in ACS compared with the control group but not when compared with stable CAD. Immunofluorescence of EAT sections revealed a significantly greater number of CD68(+) cells in ACS patients than stable CAD and control groups. The permeability of endothelial cells in vitro was significantly increased after exposure to supernatant of cultured EAT from ACS, but not control or stable CAD groups, and this effect was normalized by anti-resistin antiserum. We found that EAT of patients with ACS is characterized by increased expression and secretion of resistin and associated with increased in vitro endothelial cell permeability.

Bortezomib induces autophagic death in proliferating human endothelial cells.

The proteasome inhibitor Bortezomib has been approved for the treatment of relapsed/refractory multiple myeloma (MM), thanks to its ability to induce MM cell apoptosis. Moreover, Bortezomib has antiangiogenic properties. We report that endothelial cells (EC) exposed to Bortezomib undergo death to an extent that depends strictly on their activation state. Indeed, while quiescent EC are resistant to Bortezomib, the drug results maximally toxic in EC switched toward angiogenesis with FGF, and exerts a moderate effect on subconfluent HUVEC. Moreover, EC activation state deeply influences the death pathway elicited by Bortezomib: after treatment, angiogenesis-triggered EC display typical features of apoptosis. Conversely, death of subconfluent EC is preceded by ROS generation and signs typical of autophagy, including intense cytoplasmic vacuolization with evidence of autophagosomes at electron microscopy, and conversion of the cytosolic MAP LC3 I form toward the autophagosome-associated LC3 II form. Treatment with the specific autophagy inhibitor 3-MA prevents both LC3 I/LC3 II conversion and HUVEC cell death. Finally, early removal of Bortezomib is accompanied by the recovery of cell shape and viability. These findings strongly suggest that Bortezomib induces either apoptosis or autophagy in EC; interfering with the autophagic response may potentiate the antiangiogenic effect of the drug.

Histopathology of Clinical Coronary Restenosis in Drug-Eluting Versus Bare Metal Stents

To characterize in-stent restenosis after the implantation of sirolimus-eluting stents (SES), paclitaxel-eluting stents (PES), tacrolimus-eluting stents (TES), and zotarolimus-eluting stents (ZES), 25 patients treated with drug-eluting stents (DES; 9 PES, 10 SES, 4 TES, and 2 ZES) and 19 with bare-metal stents (BMS) underwent directional coronary atherectomy for in-stent restenosis 4 to 36 months after implantation. Restenosis after DES implantation was more frequently focal and associated with smaller specimens compared to that after BMS implantation. Light and confocal microscopy were used. Histologic features were similar in DES and BMS. In-stent restenotic lesions were composed mainly of neointima containing proteoglycan-rich smooth muscle cells and fibrolipidic regions. Small inflammatory infiltrates were observed, mostly in patients with unstable angina; CD18- and/or CD3(+) cells were detected in patients with BMS and DES. Different smooth muscle cell phenotypes were observed: synthetic was more frequent with BMS and PES, intermediate with ZES, contractile or intermediate with SES, and contractile with TES. The mean proliferation index was low and comparable among stent types; cyclins B1 and D1 were expressed in all DES. In conclusion, intra-DES and intra-BMS restenotic tissue was composed mainly of smooth muscle cells with different phenotypes, proliferating at a low rate. The different smooth muscle cell phenotypes within the stent types might suggest different mechanisms of restenosis.

R5 HIV‐1 envelope attracts dendritic cells to cross the human intestinal epithelium and sample luminal virions via engagement of the CCR5

The gastrointestinal tract is a principal route of entry and site of persistence of human immunodeficiency virus type 1 (HIV‐1). The intestinal mucosa, being rich of cells that are the main target of the virus, represents a primary site of viral replication and CD4+ T‐cell depletion. Here, we show both in vitro and ex vivo that HIV‐1 of R5 but not X4 phenotype is capable of selectively triggering dendritic cells (DCs) to migrate within 30 min between intestinal epithelial cells to sample virions and transfer infection to target cells. The engagement of the chemokine receptor 5 on DCs and the viral envelope, regardless of the genetic subtype, drive DC migration. Viruses penetrating through transient opening of the tight junctions likely create a paracellular gradient to attract DCs. The formation of junctions with epithelial cells may initiate a haptotactic process of DCs and at the same time favour cell‐to‐cell viral transmission. Our findings indicate that HIV‐1 translocation across the intestinal mucosa occurs through the selective engagement of DCs by R5 viruses, and may guide the design of new prevention strategies.

Expansion of T-Cell Receptor ζdim Effector T Cells in Acute Coronary Syndromes

Objective—The T-cell receptor zeta (TCR&zgr;)-chain is a master sensor and regulator of lymphocyte responses. Loss of TCR&zgr;-chain expression has been documented during infectious and inflammatory diseases and defines a population of effector T cells (TCR&zgr;dim T cells) that migrate to inflamed tissues. We assessed the expression and functional correlates of circulating TCR&zgr;dim T cells in coronary artery disease. Methods and Results—We examined the expression of TCR&zgr;-chain by flow cytometry in 140 subjects. Increased peripheral blood CD4+ TCR&zgr;dim T cells were found in patients with acute coronary syndromes (ACS, n=66; median 5.3%, interquartile 2.6 to 9.1% of total CD4+ T cells; P<0.0001) compared to chronic stable angina (CSA, n=32; 1.6%; 1.0 to 4.1%) and controls (n=42; 1.5%; 0.5 to 2.9%). Such increase was significantly greater in ACS patients with elevated levels of C-reactive protein, and it persisted after the acute event. Moreover, TCR&zgr;dim cells were also more represented within CD8+ T cell, NK, and CD4+CD28null T cell subsets in ACS compared to CSA and controls. Finally, CD4+ and CD8+ TCR&zgr;dim T cells isolated from ACS displayed an enhanced transendothelial migratory capacity. Conclusions—TCR&zgr;dim T cells, an effector T-cell subset with transendothelial migratory ability, are increased in ACS, and may be implicated in coronary instability.

Inhibition of chemokine expression in rat inflamed paws by systemic use of the antihyperalgesic oxidized ATP

BackgroundWe previously showed that local use of periodate oxidized ATP (oATP, a selective inhibitor of P2X7 receptors for ATP) in rat paw treated with Freunds adjuvant induced a significant reduction of hyperalgesia Herein we investigate the role of oATP, in the rat paws inflamed by carrageenan, which mimics acute inflammation in humans.ResultsLocal, oral or intravenous administration of a single dose of oATP significantly reduced thermal hyperalgesia in hind paws of rats for 24 hours, and such effect was greater than that induced by diclofenac or indomethacin. Following oATP treatment, the expression of the pro-inflammatory chemokines interferon-gamma-inducible protein-10 (IP-10), mon ocyte chemoattractant protein-1 (MCP-1) and interleukin-8 (IL-8) within the inflamed tissues markedly decreased on vessels and infiltrated cells. In parallel, the immunohistochemical findings showed an impairment, with respect to the untreated rats, in P2X7 expression, mainly on nerves and vessels close to the site of inflammation. Finally, oATP treatment significantly reduced the presence of infiltrating inflammatory macrophages in the paw tissue.ConclusionTaken together these results clearly show that oATP reduces carrageenan-induced inflammation in rats.

Protective effect of EDTA preadministration on renal ischemia

BackgroundChelation therapy with sodium edetate (EDTA) improved renal function and slowed the progression of renal insufficiency in patients subjected to lead intoxication. This study was performed to identify the underlying mechanism of the ability of EDTA treatment to protect kidneys from damage.MethodsThe effects of EDTA administration were studied in a rat model of acute renal failure induced by 60 minutes ischemia followed or not by 60 minutes reperfusion. Renal ischemic damage was evaluated by histological studies and by functional studies, namely serum creatinine and blood urea nitrogen levels. Treatment with EDTA was performed 30 minutes before the induction of ischemia. Polymorphonuclear cell (PMN) adhesion capability, plasmatic nitric oxide (NO) levels and endothelial NO synthase (eNOS) renal expression were studied as well as the EDTA protection from the TNFα-induced vascular leakage in the kidneys. Data was compared by two-way analysis of variance followed by a post hoc test.ResultsEDTA administration resulted in the preservation of both functional and histological parameters of rat kidneys. PMN obtained from peripheral blood of EDTA-treated ischemized rats, displayed a significant reduction in the expression of the adhesion molecule Mac-1 with respect to controls. NO was significantly increased by EDTA administration and eNOS expression was higher and more diffuse in kidneys of rats treated with EDTA than in the controls. Finally, EDTA administration was able to prevent in vivo the TNFα-induced vascular leakage in the kidneys.ConclusionThis data provides evidence that EDTA treatment is able to protect rat kidneys from ischemic damage possibly through the stimulation of NO production.

Functional and dynamic polymerization of the ALS-linked protein TDP-43 antagonizes its pathologic aggregation

TDP-43 is a primarily nuclear RNA-binding protein, whose abnormal phosphorylation and cytoplasmic aggregation characterizes affected neurons in patients with amyotrophic lateral sclerosis and frontotemporal dementia. Here, we report that physiological nuclear TDP-43 in mouse and human brain forms homo-oligomers that are resistant to cellular stress. Physiological TDP-43 oligomerization is mediated by its N-terminal domain, which can adopt dynamic, solenoid-like structures, as revealed by a 2.1 Å crystal structure in combination with nuclear magnetic resonance spectroscopy and electron microscopy. These head-to-tail TDP-43 oligomers are unique among known RNA-binding proteins and represent the functional form of the protein in vivo, since their destabilization results in loss of alternative splicing regulation of known neuronal RNA targets. Our findings indicate that N-terminal domain-driven oligomerization spatially separates the adjoining highly aggregation-prone, C-terminal low-complexity domains of consecutive TDP-43 monomers, thereby preventing low-complexity domain inter-molecular interactions and antagonizing the formation of pathologic aggregates.TDP-43 aggregation is observed in amyotrophic lateral sclerosis. Here the authors combine X-ray crystallography, nuclear magnetic resonance and electron microscopy studies and show that physiological oligomerization of TDP-43 is mediated through its N-terminal domain, which forms functional and dynamic oligomers antagonizing pathologic aggregation.