Erik Biros

The Interleukin 1 Beta (IL1B) Gene Is Associated with Failure to Achieve Remission and Impaired Emotion Processing in Major Depression

BACKGROUND Accumulating evidence suggests the involvement of inflammatory processes and cytokines in particular in the pathophysiology of major depression (MDD) and resistance to antidepressant treatment. Furthermore, amygdala and anterior cingulate cortex (ACC) responsiveness to emotional stimuli has been suggested as a predictor of treatment response. This study investigated the association between genetic variants of the interleukin 1 beta (IL1B) gene and amygdala and ACC responsiveness to emotional stimuli and response to antidepressant treatment. METHODS In this analysis, 256 Caucasian patients with MDD (145 women, 111 men) were genotyped for variants rs16944, rs1143643, and rs1143634 in the IL1B gene (2q14). Response to antidepressant treatment over 6 weeks was defined as remission (< or = 7 on the Hamilton Rating Scale for Depression-21-question) and response (>50% decrease on Hamilton Rating Scale for Depression-21-question). Brain activity under visual presentation of emotional faces was assessed in a subsample of 32 depressed patients by means of functional magnetic resonance imaging at 3 T. RESULTS Pharmacogenetic analyses show significant associations of the GG genotypes of single nucleotide polymorphisms (SNPs) rs16944 (odds ratio = 1.74; 95% confidence interval 1.2-4.3) and rs1143643 (odds ratio = 3.1; 95% confidence interval 1.3-7.8) (compared with the AA genotype) with nonremission after 6 weeks. The imaging analyses show that the number of G-alleles in both SNPs (rs16944 and rs1143643) was associated with reduced responsiveness of the amygdala and ACC to emotional stimulation. CONCLUSIONS The present study suggests a negative effect of the IL1B gene on pharmacological response and amygdala and ACC function involving the same genotypes of two SNPs (rs16944, rs116343), which taken together increase the risk of nonremission over 6 weeks of antidepressant treatment in MDD.

Common variants at 6p21.1 are associated with large artery atherosclerotic stroke

Genome-wide association studies (GWAS) have not consistently detected replicable genetic risk factors for ischemic stroke, potentially due to etiological heterogeneity of this trait. We performed GWAS of ischemic stroke and a major ischemic stroke subtype (large artery atherosclerosis, LAA) using 1,162 ischemic stroke cases (including 421 LAA cases) and 1,244 population controls from Australia. Evidence for a genetic influence on ischemic stroke risk was detected, but this influence was higher and more significant for the LAA subtype. We identified a new LAA susceptibility locus on chromosome 6p21.1 (rs556621: odds ratio (OR) = 1.62, P = 3.9 × 10−8) and replicated this association in 1,715 LAA cases and 52,695 population controls from 10 independent population cohorts (meta-analysis replication OR = 1.15, P = 3.9 × 10−4; discovery and replication combined OR = 1.21, P = 4.7 × 10−8). This study identifies a genetic risk locus for LAA and shows how analyzing etiological subtypes may better identify genetic risk alleles for ischemic stroke.

Role for MyD88, TLR2 and TLR9 but Not TLR1, TLR4 or TLR6 in Experimental Autoimmune Encephalomyelitis

The potential roles of TLRs in the cause and pathogenesis of autoimmune CNS inflammation remain contentious. In this study, we examined the effects of targeted deletions of TLR1, TLR2, TLR4, TLR6, TLR9, and MyD88 on the induction of myelin oligodendrocyte glycoprotein 35–55 (MOG35–55) peptide/CFA/pertussis toxin-induced autoimmune encephalomyelitis. Although C57BL/6.Tlr1−/−, C57BL/6.Tlr4−/− and C57BL/6.Tlr6−/− mice showed normal susceptibility to disease, signs were alleviated in female C57BL/6.Tlr2−/− and C57BL/6.Tlr9−/− mice and C57BL/6.Tlr2/9−/− mice of both sexes. C57BL/6.Myd88−/− mice were completely protected. Lower clinical scores were associated with reduced leukocyte infiltrates. These results were confirmed by passive adoptive transfer of disease into female C57BL/6.Tlr2−/− and C57BL/6.Tlr9−/− mice, where protection in the absence of TLR2 was associated with fewer infiltrating CD4+ cells in the CNS, reduced prevalence of detectable circulating IL-6, and increased proportions of central (CD62L+) CD4+CD25+Foxp3+ regulatory T cells. These results provide a potential molecular mechanism for the observed effects of TLR signaling on the severity of autoimmune CNS inflammation.

Downregulation of transforming growth factor, beta receptor 2 and Notch signaling pathway in human abdominal aortic aneurysm

OBJECTIVE Mutations in FBN1 and TGFBR2 genes are the main causative mutations identified in Marfan syndrome (MFS). The major vascular complication of MFS is aneurysm formation. Abdominal aortic aneurysm (AAA) is an acquired disease of later life of unknown etiology. The aim of this study was to examine if genetic aberrations in MFS-related genes FBN1 and TGFBR2 are present in patients with AAA. METHODS We assessed the presence of copy number variation (CNV) in FBN1 and TGFBR2 genes in AAA biopsies from twelve patients. We also analyzed the expression of these genes in AAA biopsies compared to control biopsies from six organ donors. In addition we assessed the expression of two members of the Notch signaling pathway NOTCH3 and HEY2 as well as aortic smooth muscle cell (AoSMC) differentiation marker TAGLN in AAA and control biopsies. RESULTS Loss of one copy (deletion) of the FBN1 exon 66 sequence and TGFBR2 exon 8 was identified in 7 (58%) and 11 (92%) of the 12 AAA biopsies. No copy number amplifications (duplications) were detected. Patients carrying TGFBR2 exon 8 deletion showed marked downregulation of this gene in AAA biopsies compared to control biopsies (0.699 vs. 1.765, p = 0.038). Notch signaling components NOTCH3 and HEY2 were markedly downregulated in AAA, while expression of the AoSMC differentiation marker TAGLN did not differ between AAA and control biopsies (0.468 vs. 0.486, p = 0.546). CONCLUSION This study suggests an acquired impairment in TGF-β signaling that along with downregulation of the Notch signaling pathway may contribute to the pathogenesis of AAA.

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.

Meta-analysis of the association between single nucleotide polymorphisms in TGF-β receptor genes and abdominal aortic aneurysm.

OBJECTIVE The role of transforming growth factor (TGF)-beta in abdominal aortic aneurysm (AAA) is controversial. The aim of this study was to assess the association of single nucleotide polymorphisms (SNPs) within TGFBR1 and TGFBR2 with AAA and infrarenal aortic diameter by combining data from previously published studies. METHODS We performed a meta-analysis using individual subject data from three independent case-control groups from Western Australia (n=1675), New Zealand (n=1209), and the Netherlands (n=1636) with 610, 601, and 693 cases of AAA (maximum infrarenal aortic diameter ≥30 mm), respectively. Data were available for two TGFBR1 (rs10819634, rs1571590) and six TGFBR2 (rs304839, rs1346907, rs1036095, rs9831477, rs9843143, rs764522) SNPs. RESULTS There was marked heterogeneity between studies. The G alleles of the TGFBR2 rs764522 and rs1036095 SNPs were associated with AAA under a recessive model (OR=1.69, 95% CI 1.28-2.25, P<0.001 and OR=1.59, 95% CI 1.23-2.07, P<0.001) when a fixed effects model was used. Both associations remained significant after adjustment for multiple testing. CONCLUSION This study suggests that two common genetic polymorphisms in TGFBR2 are associated with the risk of developing AAA although this association was mainly driven by findings in the Netherlands group and marked between study heterogeneity was detected.

The association of genetic variants of matrix metalloproteinases with abdominal aortic aneurysm: a systematic review and meta-analysis

Context Aberrant matrix turnover is believed to play a key role in the pathogenesis of abdominal aortic aneurysm (AAA). Matrix metalloproteinases (MMPs) and their inhibitors (tissue inhibitor of metalloproteinases; TIMPs) are important enzymes in the control of extracellular matrix remodelling. Objective The aim of this study was to investigate if single nucleotide polymorphisms (SNPs) within MMP and TIMP gene families are associated with the presence of AAA. Data sources We performed a search of MEDLINE and EMBASE databases on the 21st November 2012. Study selection Case-control studies assessing the association of at least one SNP in a MMP or TIMP gene with AAA were included. Data extraction Data were independently extracted by two reviewers. A random effects model was used to calculate combined odds ratios for commonly investigated SNPs according to dominant, recessive and additive inheritance. Results Thirteen studies examining 58 SNPs within 10 different MMP and TIMP genes were identified. Eight SNPs were assessed in at least 3 studies (combined sample size ranging from 141- 2191 AAA cases and 340-2013 controls) and included in a meta-analysis. Results on 1258 cases and 1406 controls for MMP3 rs3025058 showed an association with AAA presence; best described by a dominant pattern of inheritance (OR=1.48 95%CI 1.23 – 1.78, p=3.95×10-5). No associations with AAA were identified for other SNPs assessed in this study including rs1799750 (MMP1), rs3918242 (MMP9), rs486055 (MMP10), rs2276109 (MMP12), rs2252070 (MMP13), rs4898 (TIMP1) or rs9619311 (TIMP3). Conclusion A common SNP within the MMP3 promoter region, previously suggested to increase MMP3 expression, appears to be a moderate risk factor for AAA.

Association of PPARγ allelic variation, osteoprotegerin and abdominal aortic aneurysm

Objective  We have previously demonstrated high concentrations of the glycoprotein osteoprotegerin (OPG) in biopsies of abdominal aortic aneurysm (AAA), and demonstrated that ligation of the nuclear receptor peroxisome proliferator‐activated receptor gamma (PPARγ) downregulates OPG in vitro and within a mouse model. The aims of this study were to assess the associations between circulating concentrations of OPG, polymorphisms of the gene encoding PPARγ (PPARG), AAA presence and growth.

The Novel Association of the Chemokine CCL22 with Abdominal Aortic Aneurysm

The aim of this study was to examine aortic biopsies with a cytokine array to identify new cytokines associated with abdominal aortic aneurysm (AAA). We assessed the relative expression of 79 cytokines using antibody-based cytokine arrays in a total of 12 AAA and 12 control aortic biopsies. Based on these findings we validated the findings for one cytokine by examining a further 11 AAA and 11 atherothrombosis biopsies and serum from 1028 men, 315 of whom had an AAA. Three cytokines (interleukins 1B and 8, and Chemokine CC motif ligand 22 [CCL22]) were consistently up-regulated in AAA biopsies. Since CCL22 had not previously been associated with aortic dilatation, we confirmed the upregulation of this cytokine in further tissue biopsies and serum using enzyme-linked immunosorbent assay. Median serum concentrations of CCL22 were greater in men with AAA (0.69 ng/ml) than controls (0.56 ng/ml, P < 0.01). Serum CCL22 was independently associated with both small (OR 1.51, 95% CI 1.21-1.88) and large AAA (OR 1.33, 95% CI 1.08-1.62) after adjusting for other risk factors. The association between CCL22 and AAA was also confirmed using immunohistochemistry. The results presented in this study demonstrate a novel association between CCL22 and AAA as well as illustrate how a protein array can be used to identify novel markers of potential pathogenic and diagnostic significance for AAA.

Apolipoprotein E genotype is associated with serum C-reactive protein but not abdominal aortic aneurysm

OBJECTIVE Apolipoprotein E (ApoE) genotype has been associated with systemic inflammation and athero-thrombosis however the association with abdominal aortic aneurysm (AAA) has not been previously examined. We assessed the association between ApoE genotype with AAA presence and growth, and serum C-reactive protein (CRP). METHODS Serum concentrations of CRP (in 1358 men) and 6 single nucleotide polymorphisms (SNPs) for ApoE (in 1711 men) were examined in subjects from the Health In Men Study. 640 men with small AAAs were followed by ultrasound surveillance for a mean of 4.1 years. RESULTS There was no association between ApoE genotype and AAA presence. Men heterozygote for the ApoE p.Arg176Cys polymorphism had slower AAA growth, odds ratio for AAA progression> or =median 0.41, 95% confidence intervals 0.21-0.80, p=0.01. Men heterozygote for the ApoE g.50093756A>G polymorphism had slightly more rapid AAA growth, odds ratio for AAA progression> or =median 1.48, 95% confidence intervals 1.02-2.14, p=0.04. None of the ApoE SNPs were associated with AAA growth however taking into account multiple testing. Two SNPs in ApoE were associated with serum CRP under a co-dominant model, ApoE p.Cys130Arg (SNP ID rs429358), p=0.00003 and ApoE g.50114786A>G (SNP ID rs4420638), p=0.00013. Adjusting for other risk factors plus serum creatinine the varepsilon4 allele was associated with lower serum CRP under a dominant model, coefficient 0.089, p=0.002. CONCLUSION We found no consistent association between ApoE genotype and AAA. We confirmed an association between ApoE genotype and serum CRP.