Transfer of hepatocellular microRNA regulates cytochrome P450 2E1 in renal tubular cells.

BACKGROUND: Extracellular microRNAs enter kidney cells and modify gene expression. We used a Dicer-hepatocyte-specific microRNA conditional-knock-out (Dicer-CKO) mouse to investigate microRNA transfer from liver to kidney. METHODS: Dicerflox/flox mice were treated with a Cre recombinase-expressing adenovirus (AAV8) to selectively inhibit hepatocyte microRNA production (Dicer-CKO). Organ microRNA expression was measured in health and following paracetamol toxicity. The functional consequence of hepatic microRNA transfer was determined by measuring the expression and activity of cytochrome P450 2E1 (target of the hepatocellular miR-122), and by measuring the effect of serum extracellular vesicles (ECVs) on proximal tubular cell injury. In humans with liver injury we measured microRNA expression in urinary ECVs. A murine model of myocardial infarction was used as a non-hepatic model of microRNA release. FINDINGS: Dicer-CKO mice demonstrated a decrease in kidney miR-122 in the absence of other microRNA changes. During hepatotoxicity, miR-122 increased in kidney tubular cells; this was abolished in Dicer-CKO mice. Depletion of hepatocyte microRNA increased kidney cytochrome P450 2E1 expression and activity. Serum ECVs from mice with hepatotoxicity increased proximal tubular cell miR-122 and prevented cisplatin toxicity. miR-122 increased in urinary ECVs during human hepatotoxicity. Transfer of microRNA was not restricted to liver injury -miR-499 was released following cardiac injury and correlated with an increase in the kidney. INTERPRETATION: Physiological transfer of functional microRNA to the kidney is increased by liver injury and this signalling represents a new paradigm for understanding the relationship between liver injury and renal function. FUNDING: Kidney Research UK, Medical Research Scotland, Medical Research Council.

Eosinophil Deficiency Promotes Aberrant Repair and Adverse Remodeling Following Acute Myocardial Infarction.

In ST-segment elevation myocardial infarction of both patients and mice, there was a decline in blood eosinophil count, with activated eosinophils recruited to the infarct zone. Eosinophil deficiency resulted in attenuated anti-inflammatory macrophage polarization, enhanced myocardial inflammation, increased scar size, and deterioration of myocardial structure and function. Adverse cardiac remodeling in the setting of eosinophil deficiency was prevented by interleukin-4 therapy.

3D angle-independent Doppler and speckle tracking for the myocardium and blood flow

A technology based on velocity ratio indices is described for application in the myocardium. Angle-independent Doppler indices, such as the pulsatility index, which employ velocity ratios, can be measured even if the ultrasound beam vector at the moving target and the motion vector are not in a known plane. The unknown plane situation is often encountered when an ultrasound beam interrogates sites in the myocardium. The velocities employed in an index calculation must be close to the same or opposite directions. The Doppler velocity ratio indices are independent of angle in 3D space as are ratio indices based on 1D strain and 1D speckle tracking. Angle-independent results with spectral Doppler methods are discussed. Possible future imaging techniques based on velocity ratios are presented. By using indices that involve ratios, several other sources of error cancel in addition to that of angular dependence for example errors due to less than optimum gain settings and beam distortion. This makes the indices reliable as research or clinical tools. Ratio techniques can be readily implemented with current commercial blood flow pulsed wave duplex Doppler equipment or with pulsed wave tissue Doppler equipment. In 70 patients where the quality of the real-time B-mode looked suitable for the Doppler velocity ratio technique, there was only one case where clear spectra could not be obtained for both the LV wall and the septum. A reproducibility study of spectra from the septum of the heart shows a 12% difference in velocity ratios in the repeat measurements.

A Context-Dependent Role for αv Integrins in Regulatory T Cell Accumulation at Sites of Inflammation.

Several inflammatory diseases including multiple sclerosis and inflammatory bowel disease have been associated with dysfunctional and/or reduced numbers of Foxp3+ regulatory T cells (Treg). While numerous mechanisms of action have been discovered by which Treg can exert their function, disease-specific Treg requirements remain largely unknown. We found that the integrin αv, which can pair with several ß subunits including ß8, is highly upregulated in Treg at sites of inflammation. Using mice that lacked αv expression or ß8 expression specifically in Treg, we demonstrate that there was no deficit in Treg accumulation in the central nervous system during experimental autoimmune encephalomyelitis and no difference in the resolution of disease compared to control mice. In contrast, during a curative T cell transfer model of colitis, Treg lacking all αv integrins were found at reduced proportions and numbers in the inflamed gut. This led to a quantitative impairment in the ability of αv-deficient Treg to reverse disease when Treg numbers in the inflamed colon were below a threshold. Increase of the number of curative Treg injected was able to rescue this phenotype, indicating that αv integrins were not required for the immunosuppressive function of Treg per se. In accordance with this, αv deficiency did not impact on the capacity of Treg to suppress proliferation of naive conventional T cells in vitro as well as in vivo. These observations demonstrate that despite the general upregulation of αv integrins in Treg at sites of inflammation, they are relevant for adequate Treg accumulation only in specific disease settings. The understanding of disease-specific mechanisms of action by Treg has clear implications for Treg-targeted therapies.

Systemic Atherosclerotic Inflammation Following Acute Myocardial Infarction: Myocardial Infarction Begets Myocardial Infarction.

BACKGROUND: Preclinical data suggest that an acute inflammatory response following myocardial infarction (MI) accelerates systemic atherosclerosis. Using combined positron emission and computed tomography, we investigated whether this phenomenon occurs in humans. METHODS AND RESULTS: Overall, 40 patients with MI and 40 with stable angina underwent thoracic 18F-fluorodeoxyglucose combined positron emission and computed tomography scan. Radiotracer uptake was measured in aortic atheroma and nonvascular tissue (paraspinal muscle). In 1003 patients enrolled in the Global Registry of Acute Coronary Events, we assessed whether infarct size predicted early (≤30 days) and late (>30 days) recurrent coronary events. Compared with patients with stable angina, patients with MI had higher aortic 18F-fluorodeoxyglucose uptake (tissue-to-background ratio 2.15±0.30 versus 1.84±0.18, P<0.0001) and plasma C-reactive protein concentrations (6.50 [2.00 to 12.75] versus 2.00 [0.50 to 4.00] mg/dL, P=0.0005) despite having similar aortic (P=0.12) and less coronary (P=0.006) atherosclerotic burden and similar paraspinal muscular 18F-fluorodeoxyglucose uptake (P=0.52). Patients with ST-segment elevation MI had larger infarcts (peak plasma troponin 32 300 [10 200 to >50 000] versus 3800 [1000 to 9200] ng/L, P<0.0001) and greater aortic 18F-fluorodeoxyglucose uptake (2.24±0.32 versus 2.02±0.21, P=0.03) than those with non-ST-segment elevation MI. Peak plasma troponin concentrations correlated with aortic 18F-fluorodeoxyglucose uptake (r=0.43, P=0.01) and, on multivariate analysis, independently predicted early (tertile 3 versus tertile 1: relative risk 4.40 [95% CI 1.90 to 10.19], P=0.001), but not late, recurrent MI. CONCLUSIONS: The presence and extent of MI is associated with increased aortic atherosclerotic inflammation and early recurrent MI. This finding supports the hypothesis that acute MI exacerbates systemic atherosclerotic inflammation and remote plaque destabilization: MI begets MI. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01749254.

Is myocardial ischemia really bad for you?

The assessment of myocardial ischemia represents a cornerstone in our approach to coronary artery disease. Indeed many of the clinical decisions we make revolve around the results of stress testing, the assessment of coronary luminal stenoses and, more recently, fractional flow reserve measurements. Whilst the assessment of ischemia is often useful with respect to diagnosis and its treatment important in terms of symptom relief, whether ischemia directly leads to adverse cardiovascular outcomes, in particular myocardial infarction, is much more controversial. Indeed this is one of the key questions facing cardiology practice today and the focus of an ongoing multimillion-dollar study, the ISCHEMIA trial. In this editorial the authors examine some of the underlying evidence and ask the question: is ischemia itself really bad for you?

Eosinophil count predicts mortality following percutaneous coronary intervention.

INTRODUCTION: Several inflammatory markers have been shown to be independent predictors for both the development of clinically significant atherosclerosis and for adverse outcome in patients with symptomatic coronary artery disease (CAD). We investigated the prognostic role of eosinophil count in low to intermediate risk patients with CAD. METHODS: We studied 909 patients admitted for elective or urgent percutaneous coronary intervention (PCI) from April 2002 to December 2004, and measured pre-procedural total and differential white blood cell (WBC) counts. Inter-tertile WBC differences in short (6months) and long term (up to 74months) mortality were analysed after adjusting for differences in baseline characteristics. RESULTS: Over a median period of 54months (inter-quartile range 47-65), a total of 138 deaths (15.2%) occurred, of which 24 were in the first 6months of follow-up. Cox regression analysis showed that high pre-procedural eosinophil count (top tertile) was associated with improved outcome within the first 6months (OR=0.23 [0.06-0.84]; p=0.03) but after this period there was an increased risk of mortality (OR=2.21, [1.26-3.88]; p=0.006). CONCLUSIONS: Eosinophil count is a novel biomarker for risk stratification of CAD patients, which was associated initially with reduced mortality, but after 6months with increased mortality.

Tissue oxygen saturation and outcome after cardiac surgery.

BACKGROUND: Cardiopulmonary bypass during cardiac surgery can result in a shortfall in oxygen delivery relative to demand, marked by a decrease in muscle tissue oxygen saturation as blood flow is redistributed to vital organs. Such "tissue shock" might impair postoperative recovery. OBJECTIVES: To determine the association of changes in tissue oxygen saturation with postoperative outcome in cardiac surgery patients. METHODS: In 74 adults undergoing cardiac surgery, tissue oxygen saturation in the thenar eminence was recorded using near-infrared spectroscopy before and during induction of anesthesia, throughout surgery, and in the intensive care unit until extubation or for a maximum monitoring time of 24 hours. The measurements were related to postoperative outcome. RESULTS: Mean tissue oxygen saturation increased from 81.7% to 88.5% with induction of anesthesia and decreased to 78.9% and 69.9% during surgery and on arrival in the intensive care unit, respectively. Saturation increased to 77.8% by 6 hours after surgery and remained stable. Mean saturation during the first minutes of anesthesia and 20 minutes in the intensive care unit was lower in patients with a postoperative morbidity than in patients without such morbidity on day 15 (81.1% vs 87.6%; P = .04) and on day 3 (72.9% vs 85.5%; P = .009). No associations with other outcome measures were observed. CONCLUSIONS: In patients undergoing cardiac surgery, reduced tissue oxygen saturation in the thenar eminence may be associated with poor postoperative outcome. Further studies are needed to confirm these findings and to determine whether measures to improve the balance between oxygen delivery and consumption might improve both tissue oxygen saturation and outcome.

Age >or=75 years is associated with greater resource utilization following coronary artery bypass grafting.

We examined whether complication rates and resource utilization among elderly patients undergoing coronary artery bypass grafting (CABG) differed from their younger counterparts. A retrospective review of prospectively collected data was conducted of 2936 patients undergoing first-time isolated CABG. Demographic and baseline clinical characteristics were collected, and patients grouped according to age into those <75 years (n=2424, younger) and >or=75 years (n=512, older). Major postoperative complications were recorded and data collected on indicators of resource utilization, which included intensive care unit (ICU) length of stay (LOS), postoperative LOS and total hospital LOS. In comparison with younger patients, older patients were more likely to be female (26.6% vs. 18.1%, P<0.0001) and require an urgent procedure (46.4% vs. 33.3%, P<0.0001). Postoperative complications were significantly higher in elderly patients (43.7% vs. 23.0%; odds ratio (OR)=2.5, 95% confidence interval (CI) [2.0-3.1]; P<0.0001). Older patients incurred longer intensive care stays (2 days interquartile range (IQR) [1-3] vs. 1 day IQR [1-2]; P<0.0001) and a longer postoperative stay (8 days IQR [6-11] vs. 6 days IQR [5-8]; P<0.0001). Multivariate logistic regression analysis showed age >or=75 years was an independent predictor of postoperative LOS (OR=1.23, 95% CI [0.49-1.96]; P=0.001). Older patients aged >or=75 years undergoing CABG had significantly higher rates of postoperative complications and greater resource utilization than their younger counterparts.

Preprocedural hemoglobin predicts outcome in peripheral vascular disease patients undergoing percutaneous transluminal angioplasty.

BACKGROUND: Anemia is a risk factor for adverse outcome in patients with symptomatic cardiovascular disease. This study assessed the association of preprocedural hemoglobin with adverse outcome in patients with advanced peripheral vascular disease (PVD) undergoing percutaneous transluminal angioplasty (PTA). METHODS: Consecutive first-time procedures for patients with Rutherford category 4 or 5 PVD who underwent successful nonemergency PTA were analyzed in a retrospective cohort study. Cardiovascular risk factors, preprocedural hemoglobin, and angiographic data were recorded. Preprocedural (

Resolution-phase macrophages possess a unique inflammatory phenotype that is controlled by cAMP.

Neutralizing injurious stimuli, proinflammatory mediator catabolism, and polymorphonuclear leukocyte (PMN) clearance are determinants of inflammatory resolution. To this, we recently added innate-type lymphocyte repopulation as being central for restoring postinflammation tissue homeostasis with a role in controlling innate immune-mediated responses to secondary infection. However, although macrophages dominate resolution, their phenotype and role in restoring tissue physiology once inflammation abates are unknown. Therefore, we isolated macrophages from the resolving phase of acute inflammation and found that compared with classically activated proinflammatory M1 cells, resolution-phase macrophages (rMs) possess weaker bactericidal properties and express an alternatively activated phenotype but with elevated markers of M1 cells including inducible cyclooxygenase (COX 2) and nitric oxide synthase (iNOS). This phenotype is controlled by cAMP, which, when inhibited, transforms rM to M1 cells. Conversely, elevating cAMP in M1 cells transforms them to rMs, with implications for cAMP in the resolution of systemic inflammation. It transpires that although rMs are dispensable for clearing PMNs during self-limiting inflammation, they are essential for signaling postresolution lymphocyte repopulation via COX 2 lipids. Thus, rM macrophages are neither classically nor alternatively activated but a hybrid of both, with a role in mediating postresolution innate-lymphocyte repopulation and restoring tissue homeostasis.

Preprocedural neutrophil count predicts outcome in patients with advanced peripheral vascular disease undergoing percutaneous transluminal angioplasty.

BACKGROUND: The neutrophil count has been associated with adverse cardiovascular events after percutaneous coronary intervention. There are limited data on risk stratification of patients with advanced peripheral vascular disease (PVD) using white blood cell (WBC) subtypes. This study assessed the association of total and differential WBC counts with adverse outcome in patients with advanced PVD undergoing percutaneous transluminal angioplasty (PTA). METHODS: In a retrospective cohort study, consecutive de novo procedures were analyzed for patients with Rutherford category 4 or 5 PVD who underwent successful nonemergency PTA. Cardiovascular risk factors, baseline total and differential WBC counts, and angiographic data were recorded. Primary outcome was a composite of events of target vessel revascularization (repeat PTA or vascular bypass operation) or lower limb amputation. RESULTS: A total of 101 patients were studied. Their mean age was 76 +/- 10 years, 54% had diabetes mellitus, 68% were hypertensive, and 12% had had previous myocardial infarction. We observed 29 events during a median period of 14 months (interquartile range, 4-26). Cox regression analysis found diabetes mellitus (odds ratio [OR], 4.67; 95% confidence interval [CI], 1.35-16.14; P = .02), Rutherford category 5 (OR, 4.18; 95% CI, 1.06-16.51; P = .04), poor tibial runoff (OR, 4.42; 95% CI, 1.16-16.82; P = .03), and preprocedural neutrophil count in the third tertile (OR, 10.77; 95% CI, 2.19-52.91; P = .003) were independent predictors of outcome. CONCLUSIONS: The results suggest that the preprocedural neutrophil count could be used in global risk factor assessment of patients with advanced PVD who are being considered for PTA. The neutrophil count may reflect the burden of atherosclerosis and tissue damage, and so could identify patients who need more aggressive intervention for advanced PVD.

Variation in bradykinin receptor genes increases the cardiovascular risk associated with hypertension.

AIMS: The contribution of kinins to the beneficial effects of angiotensin I converting enzyme (ACE) inhibition in cardiovascular risk reduction remains unclear. The genes for the kinin inducible B1 receptor (B(1)R) and constitutive B2 receptor (B(2)R) contain functional variants: the B(1)R-699C (rather than G) and the B(2)R(-9) (rather than +9) alleles are associated with greater mRNA expression and the B(2)R(-9) allele with reduced left ventricular hypertrophic responses. We tested whether these gene variants influenced hypertensive coronary risk in a large prospective study. METHODS AND RESULTS: Two thousand, seven hundred and six previously healthy UK men (mean age at recruitment 56 years; median follow-up 10.8 years) were genotyped for the kinin receptor variants. The coronary risk attributable to systolic hypertension (SBP>/=160 mmHg) was significantly higher only in B(1)R-699GG homozygotes (HR 2.14 [1.42-3.22]; P<0.0001) and B(2)R(+9,+9) individuals (HR 3.51 [1.69-7.28]; P=0.001) but not in B(1)R-699C allele carriers (HR 0.82 [0.28-2.42]; P=0.76) or in B(2)R(-9,-9) homozygotes (HR 1.25 [0.51-3.04]; P=0.63). CONCLUSIONS: Common variation in the genes for the kinin B(1)and B(2)receptors influences prospective hypertensive coronary risk. These are the first reported human data to suggest a role for the B(1)R in human coronary vascular disease, and the first prospective study to demonstrate a similar role for the B(2)R.

Genetic variants of angiotensin II receptors and cardiovascular risk in hypertension.

Renin-angiotensin systems may mediate cardiovascular disease pathogenesis through a balance of actions of angiotensin II on (potentially proatherogenic) constitutive type 1 (AT1R) and (potentially antiatherogenic) inducible type 2 (AT2R) receptors. We explored such potential roles in a prospective candidate gene association study. Cardiovascular end points (fatal, nonfatal, and silent myocardial infarction and coronary artery bypass surgery/angioplasty) were documented among 2579 healthy UK men (mean age, 56.1+/-3.5 years; median follow-up, 10.1 years) genotyped for the AT1R1166A>C and the X chromosome located AT2R1675A>G and 3123C>A polymorphisms. Baseline characteristics, including blood pressure, were independent of genotype. The AT1R1166CC genotype was associated with relative cardiovascular risk (hazard ratio, 1.65 [1.05 to 2.59]; P=0.03) independent of blood pressure. Systolic blood pressure was associated with risk (P=0.0005), but this association was restricted to AT2R1675A allele carriers (P<0.00001), with G allele carriers protected from the risk associated with blood pressure (P=0.18). Hypertensive carriers with the AT2R1675A/3123A haplotype were at most risk, with 37.5% having an event. This is the first study to demonstrate an association of AT2R genotype with coronary risk, an effect that was confined to hypertensive subjects and supports the concept that the inducible AT2R is protective. Conversely, the AT1R1166CC genotype was associated with cardiovascular risk irrespective of blood pressure. These data are important to our understanding of the divergent role of angiotensin II acting at its receptor subtypes and coronary disease pathogenesis and for the development of future cardiovascular therapies.