Elena Vecile

Evidence of CXC, CC and C chemokine production by lymphatic endothelial cells

Although production of chemokines by vascular endothelial cells has been documented, there is only limited information regarding the expression of chemokines by the lymphatic endothelium. Here we used lymphatic endothelial cells (LEC) derived from experimentally induced murine lymphangiomas to investigate the pattern of chemokine expression by these cells. Histological analysis of the lymphatic hyperplasia revealed the presence of leucocytes in the tissues surrounding the lesions, suggesting the presence of chemoattractant activity. A functional chemotactic assay on human polymorphonuclear cells and on purified subpopulations of murine leucocytes using culture supernatants from LEC primary cultures confirmed the presence of chemoattractant activity. The identity of different cytokines of the CXC, CC and C subfamilies was investigated by reverse trancriptase–polymerase chain reaction on total endothelial cell RNA. Amplified fragments corresponding to KC, IP10, Mig‐1, BCL, MIP‐2, SLC, RANTES, MCP‐1, C10, and Lptn were obtained, and confirmed by Southern blot and sequencing. In contrast, MIP‐1α, MIP‐1β, and MIP‐1γ were not detected. Higher levels of expression were revealed by Northern blot analysis for Mig‐1, MCP‐1 and C10. The lymphatic endothelium‐restricted production of these chemokines was also confirmed by in situ hybridization. The presence of high C10 mRNA expression levels in LEC was particularly unexpected, because the production of this molecule has been previously identified only in cells of the haematopoietic lineage. These observations represent the first detailed analysis of chemokine production by lymphatic endothelial cells and may account, in part, for the mechanism of leucocyte recruitment into the lymphatics, and of lymphocyte recirculation within the lymphatic system.

Alterations in the interleukin-1/interleukin-1 receptor antagonist balance modulate cardiac remodeling following myocardial infarction in the mouse.

Background Healing after acute myocardial infarction (AMI) is characterized by an intense inflammatory response and increased Interleukin-1 (IL-1) tissue activity. Genetically engineered mice lacking the IL-1 receptor (IL-1R1-/-, not responsive to IL-1) or the IL-1 receptor antagonist (IL-1Ra, enhanced response to IL-1) have an altered IL-1/IL-1Ra balance that we hypothesize modulates infarct healing and cardiac remodeling after AMI. Methods IL-1R1-/- and IL-1Ra-/- male mice and their correspondent wild-types (WT) were subjected to permanent coronary artery ligation or sham surgery. Infarct size (trichrome scar size), apoptotic cell death (TUNEL) and left ventricular (LV) dimensions and function (echocardiography) were measured prior to and 7 days after surgery. Results When compared with the corresponding WT, IL-1R1-/- mice had significantly smaller infarcts (−25%), less cardiomyocyte apoptosis (−50%), and reduced LV enlargement (LV end-diastolic diameter increase [LVEDD], −20%) and dysfunction (LV ejection fraction [LVEF] decrease, −50%), whereas IL-1Ra-/- mice had significantly larger infarcts (+75%), more apoptosis (5-fold increase), and more severe LV enlargement (LVEDD increase,+30%) and dysfunction (LVEF decrease, +70%)(all P values <0.05). Conclusions An imbalance in IL-1/IL-1Ra signaling at the IL-1R1 level modulates the severity of cardiac remodeling after AMI in the mouse, with reduced IL-1R1 signaling providing protection and unopposed IL-1R1 signaling providing harm.

Relevance of interleukin-1 receptor antagonist intron-2 polymorphism in ischemic stroke.

Evidence of inflammatory phenomena associated with atherosclerotic plaques is extensive. Interleukin-1 (IL-1) is one of the key modulators of the inflammatory response, and its activity is critically regulated by its receptor antagonist (IL-1Ra). A variable number of tandem repeats (VNTR) in intron 2 of the human IL-1Ra shows a common polymorphism that has been related to different production of IL-1Ra and IL-1 proteins. In monocytes, the less common allele 2 has been associated with an increased production of IL-1Ra and a decreased production of IL-1. Moreover, a cooperative effect with a C to T polymorphism in the promoter of IL-1β gene (C–511→T) has been described. In the present study, we investigated the frequency of these polymorphisms in 110 subjects who survived an ischemic stroke, in 101 healthy age-matched individuals, and in a population-based sample of 1,303 healthy Italians. The frequency of the IL- 1Ra 1/1 genotype was significantly higher in stroke survivors with respect to age-matched controls (77.2 and 45.5%, respectively; p < 0.001), and to the wide group of healthy Italians (77.2 and 51.9%, respectively; p < 0.001). As expected, the estimated frequency of the IL-1Ra allele 1 (Ra*1 allele) in stroke survivors was higher than in age-matched controls (0.851 and 0.664, respectively; p < 0.001) and in healthy Italians (0.851 and 0.717, respectively; p < 0.001). Thus, ischemic stroke survivors that carry the Ra*1 allele showed a strong association with the disease with respect to age-matched controls [odds ratio (OR) = 3.905; 95% confidence interval (CI), 2.110–7.229] and healthy Italians [OR = 3.256 (95% CI, 1.971–5.379)]. No significant association was seen for the IL-1β (C–511→T) polymorphism. However, in stroke survivors, an association between the Ra*1 allele and the C allele of the IL-1β (-511) polymorphism was found (p < 0.001). Our results implicate the IL-1Ra gene in the susceptibility to ischemic stroke, and suggest that IL-1Ra genotyping may be useful in the identification of patient subgroups for pharmacological intervention in IL-1 production or actions.

Plasma concentrations of interleukin‐2 soluble receptor in mild ischaemic left ventricular dysfunction

Inflammation is increasingly thought to play a key role in promoting coronary atherosclerosis w1x. Inflammatory markers, such as C-reactive protein (CRP) have been found to be elevated in patients with acute coronary syndromes and to be predictive of adverse cardiac events w2–5x. Similarly, increased levels of inflammatory cytokines have been shown in congestive heart failure w6x (CHF) and follow the progression of the disease to its terminal phases w7x (end-stage CHF ). Whether activation of the inflammatory-immune system is induced in the early phases of ischaemic left ventricular dysfunction (LVD) remains to be determined.

Intracellular Function of Interleukin-1 Receptor Antagonist in Ischemic Cardiomyocytes

Background Loss of cardiac myocytes due to apoptosis is a relevant feature of ischemic heart disease. It has been described in infarct and peri-infarct regions of the myocardium in coronary syndromes and in ischemia-linked heart remodeling. Previous studies have provided protection against ischemia-induced cardiomyocyte apoptosis by the anti-inflammatory cytokine interleukin-1 receptor-antagonist (IL-1Ra). Mitochondria triggering of caspases plays a central role in ischemia-induced apoptosis. We examined the production of IL-1Ra in the ischemic heart and, based on dual intra/extracellular function of some other interleukins, we hypothesized that IL-1Ra may also directly inhibit mitochondria-activated caspases and cardiomyocyte apoptosis. Methodology/Principal Findings Synthesis of IL-1Ra was evidenced in the hearts explanted from patients with ischemic heart disease. In the mouse ischemic heart and in a mouse cardiomyocyte cell line exposed to long-lasting hypoxia, IL-1Ra bound and inhibited mitochondria-activated caspases, whereas inhibition of caspase activation was not observed in the heart of mice lacking IL-1Ra (Il-1ra−/−) or in siRNA to IL-1Ra-interfered cells. An impressive 6-fold increase of hypoxia-induced apoptosis was observed in cells lacking IL-1Ra. IL-1Ra down-regulated cells were not protected against caspase activation and apoptosis by knocking down of the IL-1 receptor, confirming the intracellular, receptor-independent, anti-apoptotic function of IL-1Ra. Notably, the inhibitory effect of IL-1Ra was not influenced by enduring ischemic conditions in which previously described physiologic inhibitors of apoptosis are neutralized. Conclusions/Significance These observations point to intracellular IL-1Ra as a critical mechanism of the cell self-protection against ischemia-induced apoptosis and suggest that this cytokine plays an important role in the remodeling of heart by promoting survival of cardiomyocytes in the ischemic regions.