The nuclear receptor LXR modulates interleukin-18 levels through multiple mechanisms

IL-18 is a member of the IL-1 family involved in innate immunity and inflammation. Deregulated levels of IL-18 are involved in the pathogenesis of multiple disorders including inflammatory and metabolic diseases, yet relatively little is known regarding its regulation. Liver X receptors or LXRs are key modulators of macrophage cholesterol homeostasis and immune responses. Here we show that LXR ligands negatively regulate LPS-induced mRNA and protein expression of IL-18 in bone marrow-derived macrophages. Consistent with this being an LXR-mediated process, inhibition is abolished in the presence of a specific LXR antagonist and in LXR-deficient macrophages. Additionally, IL-18 processing of its precursor inactive form to its bioactive state is inhibited by LXR through negative regulation of both pro-caspase 1 expression and activation. Finally, LXR ligands further modulate IL-18 levels by inducing the expression of IL-18BP, a potent endogenous inhibitor of IL-18. This regulation occurs via the transcription factor IRF8, thus identifying IL-18BP as a novel LXR and IRF8 target gene. In conclusion, LXR activation inhibits IL-18 production through regulation of its transcription and maturation into an active pro-inflammatory cytokine. This novel regulation of IL-18 by LXR could be applied to modulate the severity of IL-18 driven metabolic and inflammatory disorders

Differences in the Tumor Microenvironment between African-American and European-American Breast Cancer Patients

Background: African-American breast cancer patients experience higher mortality rates than European-American patients despite having a lower incidence of the disease. We tested the hypothesis that intrinsic differences in the tumor biology may contribute to this cancer health disparity. Methods and Results: Using laser capture microdissection, we examined genome-wide mRNA expression specific to tumor epithelium and tumor stroma in 18 African-American and 17 European-American patients. Numerous genes were differentially expressed between these two patient groups and a two-gene signature in the tumor epithelium distinguished between them. To identify the biological processes in tumors that are different by race/ethnicity, Gene Ontology and disease association analyses were performed. Several biological processes were identified which may contribute to enhanced disease aggressiveness in African-American patients, including angiogenesis and chemotaxis. African-American tumors also contained a prominent interferon signature. The role of angiogenesis in the tumor biology of African-American

IL-27 Regulates IL-18 Binding Protein in Skin Resident Cells

IL-18 is an important mediator involved in chronic inflammatory conditions such as cutaneous lupus erythematosus, psoriasis and chronic eczema. An imbalance between IL-18 and its endogenous antagonist IL-18 binding protein (BP) may account for increased IL-18 activity. IL-27 is a cytokine with dual function displaying pro- and anti-inflammatory properties. Here we provide evidence for a yet not described anti-inflammatory mode of action on skin resident cells. Human keratinocytes and surprisingly also fibroblasts (which do not produce any IL-18) show a robust, dose-dependent and highly inducible mRNA expression and secretion of IL-18BP upon IL-27 stimulation. Other IL-12 family members failed to induce IL-18BP. The production of IL-18BP peaked between 48–72 h after stimulation and was sustained for up to 96 h. Investigation of the signalling pathway showed that IL-27 activates STAT1 in human keratinocytes and that a proximal GAS site at the IL-18BP promoter is of importance for the functional activity of IL-27. The data are in support of a significant anti-inflammatory effect of IL-27 on skin resident cells. An important novel property of IL-27 in skin pathobiology may be to counter-regulate IL-18 activities by acting on keratinocytes and importantly also on dermal fibroblasts

Is the inflammasome a potential therapeutic target in renal disease?

The inflammasome is a large, multiprotein complex that drives proinflammatory cytokine production in response to infection and tissue injury. Pattern recognition receptors that are either membrane bound or cytoplasmic trigger inflammasome assembly. These receptors sense danger signals including damage-associated molecular patterns and pathogen-associated molecular patterns (DAMPS and PAMPS respectively). The best-characterized inflammasome is the NLRP3 inflammasome. On assembly of the NLRP3 inflammasome, post-translational processing and secretion of pro-inflammatory cytokines IL-1β and IL-18 occurs; in addition, cell death may be mediated via caspase-1. Intrinsic renal cells express components of the inflammasome pathway. This is most prominent in tubular epithelial cells and, to a lesser degree, in glomeruli. Several primary renal diseases and systemic diseases affecting the kidney are associated with NLRP3 inflammasome/IL-1β/IL-18 axis activation. Most of the disorders studied have been acute inflammatory diseases. The disease spectrum includes ureteric obstruction, ischaemia reperfusion injury, glomerulonephritis, sepsis, hypoxia, glycerol-induced renal failure, and crystal nephropathy. In addition to mediating renal disease, the IL-1/ IL-18 axis may also be responsible for development of CKD itself and its related complications, including vascular calcification and sepsis. Experimental models using genetic deletions and/or receptor antagonists/antiserum against the NLRP3 inflammasome pathway have shown decreased severity of disease. As such, the inflammasome is an attractive potential therapeutic target in a variety of renal diseases

Monitoring Electricity Consumption on the - WPI Campus

This report, prepared for the Plant Services Department at Worcester Polytechnic Institute, evaluates the present status of WPI's electricity monitoring system, on a building-by-building basis. It includes a comprehensive report of the electricity meter functionality for several dormitories and academic buildings. Also, it presents a short and long-term plan to improve the school's ability to monitor its electricity consumption

Wind Power from Kites 2008

The goal of this project was to design and build a one-kilowatt scale system for generating power using a kite. Kite power has the potential to be more economical than using wind turbines because kites can fly higher than turbines can operate. In the developed system, a large windboarding kite pulls the end of a long rocking arm which turns a generator and creates electricity. This motion is repeated using a mechanism that changes the angle of attack of the kite during each cycle, thus varying its lift force and allowing a rocking motion of the arm. All sub-components of the system have been lab tested and field tested. The system has produced power under restricted conditions. A future application for this system will be in a developing nation without access to a power grid

The promoter of IL-18 binding protein: Activation by an IFN-γ-induced complex of IFN regulatory factor 1 and CCAAT/enhancer binding protein β

The IL-18 binding protein (IL-18BP) is a circulating inhibitor of the proinflammatory cytokine IL-18. It is constitutively expressed in mononuclear cells, and elevated expression is induced by IFN-γ. In this study, we characterized the IL-18BP promoter. We first showed that induction is at the transcriptional level and requires de novo protein synthesis. The IL-18BP promoter resides within 1.6 kb DNA upstream of the first exon and includes at least six regulatory elements. We identified in the basal promoter a gamma-activated sequence (GAS) proximal to the transcription start site (base 1), followed by an IFN regulatory factor 1 response element (IRF-E) and two CCAAT/enhancer binding protein β (C/EBPβ) sites, all of which are essential for basal promoter activity. Furthermore, GAS and IRF-E were essential for IFN-γ-induced transcription. Indeed, sera of IRF-1-deficient mice lacked basal and IFN-γ-induced IL-18BP. We found that after induction of IRF-1 by IFN-γ, it formed a complex with C/EBPβ, which bound to the IRF-E and GAS-containing proximal DNA. In contrast, the IFN-γ-induced signal transducer and activator of transcription 1 dimer did not associate with this GAS. In addition, we identified a silencer element and a distal enhancer at bases −1081 to −1272, which was also physically associated with IRF-1. The IRF-1–C/EBPβ complex described here probably plays a fundamental role in regulating additional IFN-γ-responsive genes