Angiopoietin-1 Treatment Reduces Inflammation but Does Not Prevent Ventilator-Induced Lung Injury

Background: Loss of integrity of the epithelial and endothelial barriers is thought to be a prominent feature of ventilator-induced lung injury (VILI). Based on its function in vascular integrity, we hypothesize that the angiopoietin (Ang)-Tie2 system plays a role in the development of VILI. The present study was designed to examine the effects of mechanical ventilation on the Ang-Tie2 system in lung tissue. Moreover, we evaluated whether treatment with Ang-1, a Tie2 receptor agonist, protects against inflammation, vascular leakage and impaired gas exchange induced by mechanical ventilation. Methods: Mice were anesthetized, tracheotomized and mechanically ventilated for 5 hours with either an inspiratory pressure of 10 cmH(2)O ('low' tidal volume similar to 7.5 ml/kg; LVT) or 18 cmH(2)O ('high' tidal volume similar to 15 ml/kg; HVT). At initiation of HVT-ventilation, recombinant human Ang-1 was intravenously administered (1 or 4 mu g per animal). Non-ventilated mice served as controls. Results: HVT-ventilation influenced the Ang-Tie2 system in lungs of healthy mice since Ang-1, Ang-2 and Tie2 mRNA were decreased. Treatment with Ang-1 increased Akt-phosphorylation indicating Tie2 signaling. Ang-1 treatment reduced infiltration of granulocytes and expression of keratinocyte-derived chemokine (KC), macrophage inflammatory protein (MIP)-2, monocyte chemotactic protein (MCP)-1 and interleukin (IL)-1 beta caused by HVT-ventilation. Importantly, Ang-1 treatment did not prevent vascular leakage and impaired gas exchange in HVT-ventilated mice despite inhibition of inflammation, vascular endothelial growth factor (VEGF) and Ang-2 expression. Conclusions: Ang-1 treatment downregulates pulmonary inflammation, VEGF and Ang-2 expression but does not protect against vascular leakage and impaired gas exchange induced by HVT-ventilatio

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

Plasma Cholesteryl Ester Transfer Protein (CETP) in Relation to Human Pathophysiology

Plasma CETP was initially isolated as a highly purified 74 kD protein. The human CETP gene is located at chromosome 16q13, near the locus of the lecithin cholesterol acyltransferase (LCAT) gene. The CETP gene consists of 16 exons, spanning 25 kb. The CETP mRNA encodes 476 amino acids. The mature CETP contains four N-linked sugars with a variable glycosylation site of 341Asn. CETP mRNA is expressed in various tissues, but liver cells, adipocytes, and macrophages are abundant sources. One of the determinants of high density lipoprotein (HDL) neutral lipid composition is plasma CETP. In incubated human plasma, transfer and equilibration of (LCAT)-generated cholesteryl ester (CE) is found. Humans, hamsters, guinea pigs, and chickens belong to a group with intermediate CETP activity. Plasma CETP binds neutral lipids CE or triglyceride (TG), and phospholipid (PL) on HDL3, but CETP selectively promotes an exchange of CE and TG among lipoproteins. On the one hand, HDL-TG can be hydrolyzed by hepatic lipase, and on the other hand, plasma CETP decreases HDL particle size via CE/TG exchange between chylomicron/VLDL and HDL. Thus, CETP thereby accelerates the catabolic rate of HDL apolipoproteins. CETP enhances HDL remodeling from large HDL to small subclasses including pre-HDL. However, CETP deficiency would decrease cholesterol esterification rate, thereby inhibiting maturation of preb-HDL to α-migrating spherical HDL. Therefore, in CETP deficiency, large-to-small HDL remodeling is decreased and preb-HDL catabolism is also decreased. © 2010 Elsevier Inc. All rights reserved.[Book Chapter