John Cardinal

MicroRNA profiling in patients with abdominal aortic aneurysms: the significance of miR-155

AAA (abdominal aortic aneurysm) is a potentially life-threatening late-onset degenerative condition. miRNAs (microRNAs), the small non-coding RNA molecules that regulate gene expression, have been shown previously to be associated with a broad range of human pathologies, including cardiovascular diseases. The aim of the present study was to identify AAA-associated miRNAs potentially contributing to AAA pathology. We analysed the expression of 124 miRNAs within AAA biopsies and serum of ten patients undergoing AAA repair, and serum from ten age- and sex-matched subjects without AAA, using the FlexmiR™ MicroRNA Assay. RNA extracted from the site of main AAA dilatation (AAA body) was compared with that extracted from the macroscopically non-dilated neck of the AAA (AAA neck). Similarly, RNA extracted from the serum of AAA patients (AAA serum) was compared with that extracted from age- and sex-matched controls (control serum). qPCR (quantitative real-time PCR), Western blot analysis and histology were performed using an independent set of six paired AAA body and neck biopsies to examine the validity of findings. Seven miRNAs were up-regulated [>2-fold difference, FDR (false discovery rate) <0.5] within AAA biopsies, of which miR-155 was the most differentially expressed (11.32-fold, FDR=0.414). This finding was confirmed by qPCR with the median relative expression of miR-155 being 3.26 and 0.63 within AAA body and AAA neck biopsies respectively (P=0.031). Circulating miR-155 was also increased in AAA patients compared with controls, with a 2.67-fold up-regulation at borderline significance (FDR=0.554). Two immunologically important miR-155 target genes, CTLA4 (cytotoxic T-lymphocyte-associated protein) and SMAD2, were assessed and found to be significantly down-regulated within AAA bodies compared with AAA necks (P=0.032 and P=0.026) as determined by qPCR and Western blotting respectively. Histology demonstrated dense accumulation of T-lymphocytes within the adventitial and outer medial layers of AAA body, but not neck tissue. The results of the present study suggest that miR-155 is overexpressed in AAA with potential implications in the pathogenesis of the condition.

Relation of reduced preclinical left ventricular diastolic function and cardiac remodeling in overweight youth to insulin resistance and inflammation

Insulin resistance (IR) and inflammation are associated with an increased risk of cardiovascular disease and may contribute to obesity cardiomyopathy. The earliest sign of obesity cardiomyopathy is impaired left ventricular (LV) diastolic function, which may be evident in obese children and adolescents. However, the precise metabolic basis of the impaired LV diastolic function remains unknown. The aims of this study were to evaluate cardiac structure and LV diastolic function by tissue Doppler imaging in overweight and obese (OW) youth and to assess the relative individual contributions of adiposity, IR, and inflammation to alterations in cardiac structure and function. We studied 35 OW (body mass index standard deviation score 2.0±0.8; non-IR n=19, IR n=16) and 34 non-OW youth (body mass index standard deviation score 0.1±0.7). LV diastolic function was reduced in OW youth compared with non-OW controls, as indicated by lower peak myocardial relaxation velocities (p<0.001) and greater filling pressures (p<0.001). OW youth also had greater LV mass index (p<0.001), left atrial volume index, and LV interventricular septal thickness (LV-IVS; both p=0.02). IR-OW youth had the highest LV filling pressures, LV-IVS, and relative wall thickness (all p<0.05). Homeostasis model of assessment-insulin resistance and C-reactive protein were negative determinants of peak myocardial relaxation velocity and positive predictors of filling pressure. Adiponectin was a negative determinant of LV-IVS, independent of obesity. In conclusion, OW youth with IR and inflammation are more likely to have adverse changes to cardiovascular structure and function which may predispose to premature cardiovascular disease in adulthood.

Effects of atorvastatin on NGAL and cystatin C in chronic kidney disease: a post hoc analysis of the LORD trial

BACKGROUND Neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C are biomarkers of kidney injury and function, respectively. This study assessed whether plasma NGAL and/or serum cystatin C predicted baseline estimated glomerular filtration rate (eGFR) and urinary protein excretion, rate of change of eGFR and urinary protein excretion and whether atorvastatin influenced changes in these biomarkers in patients with chronic kidney disease (CKD). METHODS This is a post hoc analysis of the Lipid Lowering and Onset of Renal Disease trial, a randomized double-blind, placebo-controlled trial where 88 patients with Stages 2-4 CKD received atorvastatin 10 mg/day (48) or placebo (40). Stored blood samples were analysed for NGAL and cystatin C at baseline and a mean of 1.5 and 2.9 years later. Serum creatinine and Modification of Diet in Renal Disease (MDRD) eGFR were obtained three monthly. RESULTS There were negative associations between NGAL and cystatin C and eGFR (P = 0.025 and P < 0.001, respectively) at all time points. There were no associations between baseline NGAL and cystatin C and rate of change of eGFR (P = 0.44 and P = 0.49, respectively). Baseline NGAL but not cystatin C (P = 0.043 and P = 0.35, respectively) predicted rate of change of urinary protein excretion. In atorvastatin-treated patients, NGAL decreased (mean, -7.4 ng/mL/year; SD 128.4), whereas it increased in the placebo group [mean, 4.6 ng/mL/year; SD 56.6), the difference being statistically significant (P = 0.049). CONCLUSIONS NGAL is a biomarker of existing CKD but did not predict CKD progression. Atorvastatin reduced plasma NGAL but the significance and mechanisms require further investigation. Atorvastatin had no significant effect on cystatin C.

A deletion in chromosome 6q is associated with human abdominal aortic aneurysm

Current efforts to identify the genetic contribution to abdominal aortic aneurysm (AAA) have mainly focused on the assessment of germ-line variants such as single-nucleotide polymorphisms. The aim of the present study was to assess the presence of acquired chromosomal aberrations in human AAA. Microarray data of ten biopsies obtained from the site of main AAA dilatation (AAA body) and three control biopsies obtained from the macroscopically non-dilated neck of the AAA (AAA neck) were initially compared with identified chromosomal aneuploidies using the Chromosomal Aberration Region Miner (ChARM) software. A commonly deleted segment of chromosome bands 6 (q22.1-23.2) was predicted within AAA biopsies. This finding was confirmed by quantitative real-time PCR (qPCR)-based DNA copy number assessments of an independent set of six AAA body and neck biopsies which identified a fold copy number change (∆KCt) of -1±0.35, suggesting the loss of one copy of the long interspersed nucleotide element type 1 (LINE-1) mapped to chromosome 6 (q22.1-23.2). The median relative genomic content of LINE-1 DNA was also reduced in AAA body compared with AAA neck biopsies (1.540 compared with 3.159; P=0.031). A gene important for vascular homoeostasis mapped to 6q23.1, connective tissue growth factor (CTGF), was assessed and found to be significantly down-regulated within AAA bodies compared with AAA necks (0.261 compared with 0.627; P=0.031), as determined by reverse transcription qPCR using total RNA as a template. Histology demonstrated marked staining for macrophages within AAA body biopsies. We found in vitro that the median relative genomic content of LINE-1 DNA in aortic vascular smooth muscle cells (AoSMCs) exposed to pro-inflammatory medium was ~1.5 times greater than that measured in control AoSMCs exposed to non-conditioned medium (3.044 compared with 2.040; P=0.015). Our findings suggest that acquired chromosomal aberrations associated with retrotransposon propagation may predispose to sporadic AAA.

Multiple endocrine neoplasia type 1 in childhood: how screening guidelines correlate with real life experience

Multiple linear regression models are built to predict either the adult height or the age at first menstruation, for girls with an idiopathic central precocious puberty.