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 \u3c0.05). 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

Analisi Numerica di Problemi di Convezione Naturale Turbolenta in Cavit\ue0 Rettangolari: Confronto fra Volumi di Controllo ed Elementi Finiti

LA TERMOTECNIC

Leptospira icterohemorrhagiae and leptospire peptidoglycans induce endothelial cell adhesiveness for polymorphonuclear leukocytes

We have examined the effect of the virulent Leptospira interrogans strain Teramo, serotype icterohemorrhagiae, on the adherence of human neutrophilic polymorphonuclear leukocytes (PMN) to cultured human umbilical vein endothelial cells (HEC). Selective pretreatment of HEC with intact or sonicated leptospires caused a dose- and time-dependent increase of HEC-PMN adhesion (13.2% +/- 2.5% adherence to untreated HEC versus 46.3% +/- 5.6% adherence to HEC pretreated for 4 h with 10(8) intact leptospires per ml [mean +/- standard error of six experiments; P < 0.001]). In contrast, selective leptospire pretreatment of PMN or the addition of leptospires during the adherence assay did not alter HEC-PMN adherence. Leptospire induction of endothelial-cell adhesiveness occurred without detectable HEC damage and was prevented by RNA and protein synthesis inhibitors and by monoclonal antibodies to the CD11/CD18 adhesion complex of neutrophils and to the endothelial-leukocyte adhesion molecule 1 (ELAM-1) of endothelial cells. Similar results were obtained with pretreatment of HEC with interleukin-1 or with the lipopolysaccharide (LPS) of the gram-negative bacterium Escherichia coli. The possibility that contamination by the LPS of gram-negative bacteria could be involved in the induction of HEC adhesiveness was ruled out by the observation that the LPS inhibitor polymyxin B, which abolished the proadhesive effect of E. coli LPS, was ineffective in inhibiting leptospire- as well as interleukin-1-induced adherence. Similarly, leptospire LPSs seemed to have no role in the increase of endothelial-cell adhesiveness, since pretreatment of HEC with a leptospire LPS extract (phenol-water method) or with a leptospire total lipid extract failed to induce the proadhesive phenotype for neutrophils. Instead, peptidoglycans extracted from our leptospires actively stimulated the endothelial proadhesive activity for neutrophils (16.5% +/- 2.1% adherence to untreated HEC versus 51.2% +/- 2.9% adherence to HEC pretreated for 4 h with 1 microgram of peptidoglycan per ml; [mean +/- standard error of four experiments; P < 0.001]). This peptidoglycan-induced activity was inhibited by monoclonal antibodies to the CD11/CD18 adhesion complex and to ELAM-1 but not by polymyxin B. We conclude that peptidoglycans from pathogenic leptospires are among the molecules that can directly activate vascular endothelial cells to increase their adhesiveness for neutrophilic granulocytes. These observations may contribute to a better understanding of the mechanisms whereby non-gram-negative bacteria modulate the local and systemic inflammatory reaction

Capitolo 2 : Meccanismi di difesa

Vengono descritti i meccanismi di instaurazione dell'infiammazione acuta e dell'infiammazione cronica, e i diversi aspetti che questi due tipi di infiammazione possono assumere. Inoltre vengono trattati gli effetti positivi e negativi della flogosi e le manifestazioni sistemiche dell'infiammazione (febbre, leucocitosi, modificazioni plasmatiche, metaboliche e comportamentali

How Can Interleukin-1 Receptor Antagonist Modulate Distinct Cell Death Pathways?

Multiple mechanisms of cell death exist (apoptosis, necroptosis, pyroptosis) and the subtle balance of several distinct proteins and inhibitors tightly regulates the cell fate toward one or the other pathway. Here, by combining coimmunoprecipitation, enzyme assays, and molecular simulations, we ascribe a new role, within this entangled regulatory network, to the interleukin-1 receptor antagonist (IL-1Ra). Our study enlightens that IL-1Ra, which usually inhibits the inflammatory effects of IL-1\u3b1/\u3b2 by binding to IL-1 receptor, under advanced pathological states prevents apoptosis and/or necroptosis by noncompetitively inhibiting the activity of caspase-8 and -9. Consensus docking, followed by cumulative 10 \u3bcs of molecular dynamics simulations unprecedentedly reveal that IL-1Ra binds both caspases at their dimeric interface, preventing, in this manner, the formation of their catalytically/signaling active form. The resulting IL-1Ra/caspase-8(9) adducts are stabilized by hydrophobic and by few key hydrogen bonding interactions, formed by residues fully conserved across distinct caspases (-3, -6, -7, -8, and -9), and closely resemble the binding mode of the caspases inhibitors XIAP (X-linked inhibitor of apoptosis) and c-FLIP (cellular FLICE-like inhibitory protein). Tight regulation of the different forms of cell death has a major impact on distinct human illnesses (i.e., cancer, neurodegeneration, ischemic injury, atherosclerosis, viral/bacterial infections, and immune reaction). Hence, our study, pinpointing IL-1Ra as new actor of the intricate cell death regulatory network and gaining an atomic-scale understanding of its mechanism may open new avenues toward innovative therapeutic strategies to tackle major human diseases

Soluble interleukin-2 receptor: is there a role in ischaemic cardiomyopathy?

We believe that sIL-2R levels should be regarded as markers of LV dysfunction independently from its cause. Moreover, we believe that in the current effort to understand and appraise fully the role of inflammatory mechanism in cardiac remodelling and failure, sIL-2R levels should be determined in the active phases of the disease when LV dysfunction ensues, rather than in its advanced phase

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-1beta 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 T) polymorphism. However, in stroke survivors, an association between the Ra*1 allele and the C allele of the IL-1beta (-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