Background-Inflammation plays a key role in the pathophysiology of myocardial ischemia/reperfusion (I/R) injury; however, the mechanism by which myocardial I/R induces inflammation remains unclear. Recent evidence indicates that a sterile inflammatory response triggered by tissue damage is mediated through a multiple-protein complex called the inflammasome. Therefore, we hypothesized that the inflammasome is an initial sensor for danger signal(s) in myocardial I/R injury. Methods and Results-We demonstrate that inflammasome activation in cardiac fibroblasts, but not in cardiomyocytes, is crucially involved in the initial inflammatory response after myocardial I/R injury. We found that inflammasomes are formed by I/R and that its subsequent activation of inflammasomes leads to interleukin-1␤ production, resulting in inflammatory responses such as inflammatory cell infiltration and cytokine expression in the heart. In mice deficient for apoptosis-associated speck-like adaptor protein and caspase-1, these inflammatory responses and subsequent injuries, including infarct development and myocardial fibrosis and dysfunction, were markedly diminished. Bone marrow transplantation experiments with apoptosis-associated speck-like adaptor protein-deficient mice revealed that inflammasome activation in bone marrow cells and myocardial resident cells such as cardiomyocytes or cardiac fibroblasts plays an important role in myocardial I/R injury. In vitro experiments revealed that hypoxia/reoxygenation stimulated inflammasome activation in cardiac fibroblasts, but not in cardiomyocytes, and that hypoxia/reoxygenation-induced activation was mediated through reactive oxygen species production and potassium efflux. Conclusions-Our results demonstrate the molecular basis for the initial inflammatory response after I/R and suggest that the inflammasome is a potential novel therapeutic target for preventing myocardial I/R injury. (Circulation. 2011;123:594-604.)Key Words: cytokine Ⅲ heart Ⅲ hypoxia Ⅲ inflammation Ⅲ leukocyte I ncreasing evidence indicates that inflammation is involved in the pathophysiology of myocardial ischemia/reperfusion (I/R) injury. 1 One prominent and early mediator for inflammation in I/R injury is interleukin-1␤ (IL-1␤). 2,3 I/R induces IL-1␤ expression in the heart, and the inhibition of IL-1␤ prevents myocardial injury after I/R, 3 suggesting that the deleterious effects of myocardial I/R are mediated, at least in part, by IL-1␤. In the generation of IL-1␤, pro-IL-1␤, an inactive precursor, undergoes proteolysis by the converting enzyme caspase-1. Caspase-1 is activated within a cytosolic multiprotein complex, the inflammasome. The inflammasome contains cytoplasmic receptors of the NACHT leucine-rich-repeat protein family that are associated with the apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), which in turn recruits and activates caspase-1. 4,5 Increasing evidence indicates that several sterile inflammatory responses triggered by tissue damage are mediated by th...

BackgroundHyaluronan (HA) is a primary component of the extracellular matrix of cells, and it is involved in the pathogenesis of atherosclerosis. The purpose of this study was to investigate the role of HA in neointimal formation after vascular injury and determine its tissue-specific role in vascular smooth muscle cells (VSMCs) by using a cre-lox conditional transgenic (cTg) strategy.Methods and ResultsHA was found to be expressed in neointimal lesions in humans with atherosclerosis and after wire-mediated vascular injury in mice. Inhibition of HA synthesis using 4-methylumbelliferone markedly inhibited neointimal formation after injury. In vitro experiments revealed that low-molecular-weight HA (LMW-HA) induced VSMC activation, including migration, proliferation, and production of inflammatory cytokines, and reactive oxygen species (ROS). The migration and proliferation of VSMCs were mediated by the CD44/RhoA and CD44/ERK1/2 pathways, respectively. Because HA synthase 2 (HAS2) is predominantly expressed in injured arteries, we generated cTg mice that overexpress the murine HAS2 gene specifically in VSMCs (cHAS2/CreSM22α mice) and showed that HA overexpression markedly enhanced neointimal formation after cuff-mediated vascular injury. Further, HA-overexpressing VSMCs isolated from cHAS2/CreSM22α mice showed augmented migration, proliferation, and production of inflammatory cytokines and ROS.ConclusionVSMC-derived HA promotes neointimal formation after vascular injury, and HA may be a potential therapeutic target for cardiovascular disease.

This report concerns two patients with severe protein losing enteropathy and refractory diarrhea due to AA amyloidosis who were successfully treated with corticosteroid and octreotide. In these patients, biopsied tissues from the gastrointestinal (GI) tract showed extensive deposition of AA amyloid, which was caused by rheumatoid arthritis in one case and was of unidentified etiology in the other. Both patients manifested severe diarrhea unresponsive to conventional treatment with hypoproteinemia, and protein leakage from the small intestine to the ascending colon was confirmed by 99mTc-diethylene triamine pentaacetic acid human serum albumin (HSA-D) scintigraphy. Soon after starting a long-acting somatostatin analogue, octreotide, with co-administration of oral prednisolone, their general status improved in parallel with a rapid decrease in the volume of watery diarrhea and an increase in serum levels of albumin and IgG. Also on 99mTc-HSA-D scintigraphy protein leakage from the GI tract was apparently decreased in both patients. Combination therapy with a somatostatin analogue and corticosteroid may be effective for protein losing enteropathy with intractable diarrhea ascribable to GI amyloidosis. Because of the lack of specific therapies in this serious clinical situation, the described therapy should actively be considered as a therapeutic option not only in AA amyloidosis, but also in other types of systemic amyloidosis.

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SummaryInflammatory biomarkers have been proposed for use in the risk stratification of patients with acute myocardial infarction (AMI). We examined the value of inflammatory biomarkers over clinical features for predicting cardiovascular (CV) events in stable outpatients with MI. We enrolled 430 post-MI patients and measured their levels of high-sensitivity C reactive protein (hs-CRP), growth differentiation factor-15 (GDF-15), and the interleukin-1 receptor family member called ST2 (ST2), one month after AMI. Patients were prospectively followed for 3 years. In our study cohort (mean age, 66 ± 12 years; left ventricular ejection fraction, 55 ± 13%), CV events were observed in 39 patients (9.1%). KaplanMeier analysis revealed that patients with high levels of GDF-15 (≥ 1221.0 ng/L) showed poorer prognoses than those with low levels of GDF-15 (< 1221.0 ng/L) (20.4% versus 3.6%, P < 0.001); hs-CRP and ST2 did not show a similar correlation with prognoses. GDF-15 remained associated with CV events after adjusting for age, chronic kidney disease, and B-type natriuretic peptide (hazard ratio, 1.001; 95% confidence interval, 1.000 -1.001; P = 0.046). GDF-15 provided an incremental predictive value for CV events over clinical features (incremental value in global χ 2 = 43.81, P < 0.001). In outpatients with prior MI, GDF-15 was an independent indicator of CV events, unlike hs-CRP and ST2. GDF-15 provided an incremental prognostic value over clinical features. (Int Heart J 2016; 57: 11-17) Key words: Coronary artery disease, Growth differentiation factor-15, Prognosis I nflammatory biomarkers have been proposed for use in the risk stratification of patients with cardiovascular (CV) disease. 1-7) Patients with acute myocardial infarction (AMI) are at significant risk for recurrent CV events, such as death, recurrent MI, and heart failure. Novel biomarkers for patients with AMI are of interest because they may reveal pivotal disease mechanisms and potential therapeutic targets. 8)High-sensitivity C reactive protein (hs-CRP); growth differentiation factor-15 (GDF-15), a member of the transforming growth factor-β superfamily; and ST2, a member of the interleukin-1 receptor family, are strongly associated with CV events in AMI patients. [9][10][11][12][13][14][15][16] In clinically stable patients with acute decompensated heart failure, high levels of B-type natriuretic peptide (BNP) at the end of a hospitalization are strong, independent markers of CV events compared with levels during the acute phase.17) Secondary prevention of CV events is a crucial factor for the prognostic improvement in patients with AMI, and novel biomarkers provide important information about patient management if the biomarkers contribute to the risk stratification in these patients. However, the prognostic significance of inflammatory biomarkers for risk stratification in stable post-MI outpatients is poorly understood. Editorial p.1The aims of this study were to 1) compare the prognostic significance of inflammatory biomarkers for predicting C...