Reduced plakoglobin increases the risk of sodium current defects and atrial conduction abnormalities in response to androgenic anabolic steroid abuse.

Androgenic anabolic steroids (AAS) are commonly abused by young men. Male sex and increased AAS levels are associated with earlier and more severe manifestation of common cardiac conditions, such as atrial fibrillation, and rare ones, such as arrhythmogenic right ventricular cardiomyopathy (ARVC). Clinical observations suggest a potential atrial involvement in ARVC. Arrhythmogenic right ventricular cardiomyopathy is caused by desmosomal gene defects, including reduced plakoglobin expression. Here, we analysed clinical records from 146 ARVC patients to identify that ARVC is more common in males than females. Patients with ARVC also had an increased incidence of atrial arrhythmias and P wave changes. To study desmosomal vulnerability and the effects of AAS on the atria, young adult male mice, heterozygously deficient for plakoglobin (Plako+/-), and wild type (WT) littermates were chronically exposed to 5α-dihydrotestosterone (DHT) or placebo. The DHT increased atrial expression of pro-hypertrophic, fibrotic and inflammatory transcripts. In mice with reduced plakoglobin, DHT exaggerated P wave abnormalities, atrial conduction slowing, sodium current depletion, action potential amplitude reduction and the fall in action potential depolarization rate. Super-resolution microscopy revealed a decrease in NaV1.5 membrane clustering in Plako+/- atrial cardiomyocytes after DHT exposure. In summary, AAS combined with plakoglobin deficiency cause pathological atrial electrical remodelling in young male hearts. Male sex is likely to increase the risk of atrial arrhythmia, particularly in those with desmosomal gene variants. This risk is likely to be exaggerated further by AAS use. KEY POINTS: Androgenic male sex hormones, such as testosterone, might increase the risk of atrial fibrillation in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), which is often caused by desmosomal gene defects (e.g. reduced plakoglobin expression). In this study, we observed a significantly higher proportion of males who had ARVC compared with females, and atrial arrhythmias and P wave changes represented a common observation in advanced ARVC stages. In mice with reduced plakoglobin expression, chronic administration of 5α-dihydrotestosterone led to P wave abnormalities, atrial conduction slowing, sodium current depletion and a decrease in membrane-localized NaV1.5 clusters. 5α-Dihydrotestosterone, therefore, represents a stimulus aggravating the pro-arrhythmic phenotype in carriers of desmosomal mutations and can affect atrial electrical function.

A genome-wide association study in autoimmune neurological syndromes with anti-GAD65 autoantibodies.

Autoimmune neurological syndromes (AINS) with autoantibodies against the 65 kDa isoform of the glutamic acid decarboxylase (GAD65) present with limbic encephalitis, including temporal lobe seizures or epilepsy, cerebellitis with ataxia, and stiff-person-syndrome or overlap forms. Anti-GAD65 autoantibodies are also detected in autoimmune diabetes mellitus, which has a strong genetic susceptibility conferred by human leukocyte antigen (HLA) and non-HLA genomic regions. We investigated the genetic predisposition in patients with anti-GAD65 AINS. We performed a genome-wide association study (GWAS) and an association analysis of the HLA region in a large German cohort of 1214 individuals. These included 167 patients with anti-GAD65 AINS, recruited by the German Network for Research on Autoimmune Encephalitis (GENERATE), and 1047 individuals without neurological or endocrine disease as population-based controls. Predictions of protein expression changes based on GWAS findings were further explored and validated in the CSF proteome of a virtually independent cohort of 10 patients with GAD65-AINS and 10 controls. Our GWAS identified 16 genome-wide significant (P < 5 × 10-8) loci for the susceptibility to anti-GAD65 AINS. The top variant, rs2535288 [P = 4.42 × 10-16, odds ratio (OR) = 0.26, 95% confidence interval (CI) = 0.187-0.358], localized to an intergenic segment in the middle of the HLA class I region. The great majority of variants in these loci (>90%) mapped to non-coding regions of the genome. Over 40% of the variants have known regulatory functions on the expression of 48 genes in disease relevant cells and tissues, mainly CD4+ T cells and the cerebral cortex. The annotation of epigenomic marks suggested specificity for neural and immune cells. A network analysis of the implicated protein-coding genes highlighted the role of protein kinase C beta (PRKCB) and identified an enrichment of numerous biological pathways participating in immunity and neural function. Analysis of the classical HLA alleles and haplotypes showed no genome-wide significant associations. The strongest associations were found for the DQA1*03:01-DQB1*03:02-DRB1*04:01HLA haplotype (P = 4.39 × 10-4, OR = 2.5, 95%CI = 1.499-4.157) and DRB1*04:01 allele (P = 8.3 × 10-5, OR = 2.4, 95%CI = 1.548-3.682) identified in our cohort. As predicted, the CSF proteome showed differential levels of five proteins (HLA-A/B, C4A, ATG4D and NEO1) of expression quantitative trait loci genes from our GWAS in the CSF proteome of anti-GAD65 AINS. These findings suggest a strong genetic predisposition with direct functional implications for immunity and neural function in anti-GAD65 AINS, mainly conferred by genomic regions outside the classical HLA alleles.

Cardiac chamber-specific genetic alterations suggest candidate genes and pathways implicating the left ventricle in the pathogenesis of atrial fibrillation.

It is believed that the atria play a predominant role in the initiation and maintenance of atrial fibrillation (AF), while the role of left ventricular dysfunction in the pathophysiology remains enigmatic. We sought to dissect chamber specificity of AF-associated transcriptional changes using RNA-sequencing. We performed intra- and inter-chamber differential expression analyses comparing AF against sinus rhythm to identify genes specifically dysregulated in human left atria, right atria, and left ventricle (LV), and integrated known AF genetic associations with expression quantitative trait loci datasets to inform the potential for disease causal contributions within each chamber. Inter-chamber patterns changed drastically. Vast AF-associated transcriptional changes specific to LV, enriched for biological pathway terms implicating mitochondrial function, developmental processes and immunity, were supported at the genetic level, but no major enrichments for candidate genes specific to the atria were found. Our observations suggest an active role of the LV in the pathogenesis of AF.

Evolutionarily conserved transcriptional landscape of the heart defining the chamber specific physiology.

Cardiovascular disease (CVD) remains the leading cause of death worldwide. A deeper characterization of regional transcription patterns within different heart chambers may aid to improve our understanding of the molecular mechanisms involved in myocardial function and further, our ability to develop novel therapeutic strategies. Here, we used RNA sequencing to determine differentially expressed protein coding (PC) and long non-coding (lncRNA) transcripts within the heart chambers across seven vertebrate species and identified evolutionarily conserved chamber specific genes, lncRNAs and pathways. We investigated lncRNA homologs based on sequence, secondary structure, synteny and expressional conservation and found most lncRNAs to be conserved by synteny. Regional co-expression patterns of transcripts are modulated by multiple factors, including genomic overlap, strandedness and transcript biotype. Finally, we provide a community resource designated EvoACTG, which informs researchers on the conserved yet intertwined nature of the coding and non-coding cardiac transcriptome across popular model organisms in CVD research.

Climate change facilitates a parasite's host exploitation via temperature-mediated immunometabolic processes.

Global climate change can influence organismic interactions like those between hosts and parasites. Rising temperatures may exacerbate the exploitation of hosts by parasites, especially in ectothermic systems. The metabolic activity of ectotherms is strongly linked to temperature and generally increases when temperatures rise. We hypothesized that temperature change in combination with parasite infection interferes with the host's immunometabolism. We used a parasite, the avian cestode Schistocephalus solidus, which taps most of its resources from the metabolism of an ectothermic intermediate host, the three-spined stickleback. We experimentally exposed sticklebacks to this parasite, and studied liver transcriptomes 50 days after infection at 13°C and 24°C, to assess their immunometabolic responses. Furthermore, we monitored fitness parameters of the parasite and examined immunity and body condition of the sticklebacks at 13°C, 18°C and 24°C after 36, 50 and 64 days of infection. At low temperatures (13°C), S. solidus growth was constrained, presumably also by the more active stickleback's immune system, thus delaying its infectivity for the final host to 64 days. Warmer temperature (18°C and 24°C) enhanced S. solidus growth, and it became infective to the final host already after 36 days. Overall, S. solidus produced many more viable offspring after development at elevated temperatures. In contrast, stickleback hosts had lower body conditions, and their immune system was less active at warm temperature. The stickleback's liver transcriptome revealed that mainly metabolic processes were differentially regulated between temperatures, whereas immune genes were not strongly affected. Temperature effects on gene expression were strongly enhanced in infected sticklebacks, and even in exposed-but-not-infected hosts. These data suggest that the parasite exposure in concert with rising temperature, as to be expected with global climate change, shifted the host's immunometabolism, thus providing nutrients for the enormous growth of the parasite and, at the same time suppressing immune defence.

A genetic variant alters the secondary structure of the lncRNA H19 and is associated with dilated cardiomyopathy.

lncRNAs are at the core of many regulatory processes and have also been recognized to be involved in various complex diseases. They affect gene regulation through direct interactions with RNA, DNA or proteins. Accordingly, lncRNA structure is likely to be essential for their regulatory function. Point mutations, which manifest as SNPs (single nucleotide polymorphisms) in genome screens, can substantially alter their function and, subsequently, the expression of their downstream regulated genes. To test the effect of SNPs on structure, we investigated lncRNAs associated with dilated cardiomyopathy. Among 322 human candidate lncRNAs, we demonstrate first the significant association of an SNP located in lncRNA H19 using data from 1084 diseased and 751 control patients. H19 is generally highly expressed in the heart, with a complex expression pattern during heart development. Next, we used MFE (minimum free energy) folding to demonstrate a significant refolding in the secondary structure of this 861 nt long lncRNA. Since MFE folding may overlook the importance of sub-optimal structures, we showed that this refolding also manifests in the overall Boltzmann structure ensemble. There, the composition of structures is tremendously affected in their thermodynamic probabilities through the genetic variant. Finally, we confirmed these results experimentally, using SHAPE-Seq, corroborating that SNPs affecting such structures may explain hidden genetic variance not accounted for through genome wide association studies. Our results suggest that structural changes in lncRNAs, and lncRNA H19 in particular, affect regulatory processes and represent optimal targets for further in-depth studies probing their molecular interactions.

Complement 5a Receptor Polymorphisms Are Associated With Panton-Valentine Leukocidin-positive Staphylococcus aureus Colonization in African Pygmies.

Panton-Valentine leukocidin (PVL) is common in African Staphylococcus aureus and can be associated with skin and soft tissue infection. PVL-positive S. aureus colonization is associated with a variant of complement receptor 5a, the cellular target of the lukS PVL subunit.

Suppressor of Cytokine Signaling 1 is Involved in Gene Regulation Which Controls the Survival of Ly6Clow Monocytes in Mice.

BACKGROUND/AIMS: Inflammatory processes are controlled by the fine-tuned balance of monocyte subsets. In mice, different subsets of monocytes can be distinguished by the expression of Ly6C that is highly expressed on inflammatory monocytes (Ly6Chigh) and to a lesser extent on patrolling monocytes (Ly6Clow). Our previous study revealed an accumulation of Ly6Chigh monocytes in atherosclerotic-prone mice bearing a deficiency in suppressor of cytokine signaling (SOCS)-1 leading to an increased atherosclerotic burden. To decipher the underlying mechanisms, we performed a genome-wide analysis of SOCS-1-dependent gene regulation in Ly6Chigh and Ly6Clow monocytes. METHODS: In monocyte subsets from SOCS-1competent and -deficient mice differentially regulated genes were identified using an Illumina mRNA microarray (45,200 transcripts), which were randomly validated by qPCR. Principal component analysis was performed to further characterize mRNA profiles in monocyte subsets. To unravel potential regulatory mechanisms behind the differential mRNA expression, in silico analysis of a transcription factor (TF) network correlating with SOCS-1-dependent mRNA expression was carried out and combined with a weighted correlation network analysis (WGCNA). RESULTS: mRNA analysis in monocyte subsets revealed 46 differentially regulated genes by 2-fold or more. Principal component analysis illustrated a distinct separation of mRNA profiles in monocyte subsets from SOCS-1-deficient mice. Notably, two cell surface receptors crucially involved in the determination of monocyte differentiation and survival, C-X3-C chemokine receptor 1 (CX3CR1) and colony stimulating factor 1 receptor (CSF1R), were identified to be regulated by SOCS-1. Moreover, in silico analysis of a TF network in combination with the WGCNA revealed genes coding for PPAR-γ, NUR77 and several ETSdomain proteins that act as pivotal inflammatory regulators. CONCLUSION: Our study reveals that SOCS-1 is implicated in a TF network regulating the expression of central transcription factors like PPAR-γ and NUR77 thereby influencing the expression of CX3CR1 and CSF1R that are known to be pivotal for the survival of Ly6Clow monocytes.

Transcriptomic and proteomic analysis of iris tissue and aqueous humor in juvenile idiopathic arthritis-associated uveitis.

Gene and protein expression profiles of iris biopsies, aqueous humor (AqH), and sera in patients with juvenile idiopathic arthritis-associated uveitis (JIAU) in comparison to control patients with primary open-angle glaucoma (POAG) and HLA-B27-positive acute anterior uveitis (AAU) were investigated. Via RNA Sequencing (RNA-Seq) and mass spectrometry-based protein expression analyses 136 genes and 56 proteins could be identified as being significantly differentially expressed (DE) between the JIAU and POAG group. Gene expression of different immunoglobulin (Ig) components as well as of the B cell-associated factors ID3, ID1, and EBF1 was significantly upregulated in the JIAU group as compared to POAG patients. qRT-PCR analysis showed a significantly higher gene expression of the B cell-related genes CD19, CD20, CD27, CD138, and MZB1 in the JIAU group. At the protein level, a significantly higher expression of Ig components in JIAU than in POAG was confirmed. The B cell-associated protein MZB1 showed a higher expression in JIAU patients than in POAG which was confirmed by western blot analysis. Using bead-based immunoassay analysis we were able to detect a significantly higher concentration of the B cell-activating and survival factors BAFF, APRIL, and IL-6 in the AqH of JIAU and AAU patients than in POAG patients. The intraocularly upregulated B cell-specific genes and proteins in iris tissue suggest that B cells participate in the immunopathology of JIAU. The intracameral environment in JIAU may facilitate local effector and survival functions of B cells, leading to disease course typical for anterior uveitis.

Rare genetic variants in SMAP1, B3GAT2, and RIMS1 contribute to pediatric venous thromboembolism.

Recent genome-wide association studies (GWAS) have confirmed known risk mutations for venous thromboembolism (VTE) and identified a number of novel susceptibility loci in adults. Here we present a GWAS in 212 nuclear families with pediatric VTE followed by targeted next-generation sequencing (NGS) to identify causative mutations contributing to the association. Three single nucleotide polymorphisms (SNPs) exceeded the threshold for genome-wide significance as determined by permutation testing using 100 000 bootstrap permutations (P < 10-5). These SNPs reside in a region on chromosome 6q13 comprising the genes small ARF GAP1 (SMAP1), an ARF6 guanosine triphosphatase-activating protein that functions in clathrin-dependent endocytosis, and ß-1,3-glucoronyltransferase 2 (B3GAT2), a member of the human natural killer 1 carbohydrate pathway. Rs1304029 and rs2748331 are associated with pediatric VTE with unpermuted/permuted values of P = 1.42 × 10-6/2.0 × 10-6 and P = 6.11 × 10-6/1.8 × 10-5, respectively. Rs2748331 was replicated (P = .00719) in an independent study sample coming from our GWAS on pediatric thromboembolic stroke (combined P = 7.88 × 10-7). Subsequent targeted NGS in 24 discordant sibling pairs identified 17 nonsynonymous coding variants, of which 1 located in SMAP1 and 3 in RIMS1, a member of the RIM family of active zone proteins, are predicted as damaging by Protein Variation Effect Analyzer and/or sorting intolerant from tolerant scores. Three SNPs curtly missed statistical significance in the transmission-disequilibrium test in the full cohort (rs112439957: P = .08326, SMAP1; rs767118962: P = .08326, RIMS1; and rs41265501: P = .05778, RIMS1). In conjunction, our data provide compelling evidence for SMAP1, B3GAT2, and RIMS1 as novel susceptibility loci for pediatric VTE and warrant future functional studies to unravel the underlying molecular mechanisms leading to VTE.

Multiple phenotypes in phosphoglucomutase 1 deficiency.

BACKGROUND: Congenital disorders of glycosylation are genetic syndromes that result in impaired glycoprotein production. We evaluated patients who had a novel recessive disorder of glycosylation, with a range of clinical manifestations that included hepatopathy, bifid uvula, malignant hyperthermia, hypogonadotropic hypogonadism, growth retardation, hypoglycemia, myopathy, dilated cardiomyopathy, and cardiac arrest. METHODS: Homozygosity mapping followed by whole-exome sequencing was used to identify a mutation in the gene for phosphoglucomutase 1 (PGM1) in two siblings. Sequencing identified additional mutations in 15 other families. Phosphoglucomutase 1 enzyme activity was assayed on cell extracts. Analyses of glycosylation efficiency and quantitative studies of sugar metabolites were performed. Galactose supplementation in fibroblast cultures and dietary supplementation in the patients were studied to determine the effect on glycosylation. RESULTS: Phosphoglucomutase 1 enzyme activity was markedly diminished in all patients. Mass spectrometry of transferrin showed a loss of complete N-glycans and the presence of truncated glycans lacking galactose. Fibroblasts supplemented with galactose showed restoration of protein glycosylation and no evidence of glycogen accumulation. Dietary supplementation with galactose in six patients resulted in changes suggestive of clinical improvement. A new screening test showed good discrimination between patients and controls. CONCLUSIONS: Phosphoglucomutase 1 deficiency, previously identified as a glycogenosis, is also a congenital disorder of glycosylation. Supplementation with galactose leads to biochemical improvement in indexes of glycosylation in cells and patients, and supplementation with complex carbohydrates stabilizes blood glucose. A new screening test has been developed but has not yet been validated. (Funded by the Netherlands Organization for Scientific Research and others.).

Transcriptome assessment reveals a dominant role for TLR4 in the activation of human monocytes by the alarmin MRP8.

The alarmins myeloid-related protein (MRP)8 and MRP14 are the most prevalent cytoplasmic proteins in phagocytes. When released from activated or necrotic phagocytes, extracellular MRP8/MRP14 promote inflammation in many diseases, including infections, allergies, autoimmune diseases, rheumatoid arthritis, and inflammatory bowel disease. The involvement of TLR4 and the multiligand receptor for advanced glycation end products as receptors during MRP8-mediated effects on inflammation remains controversial. By comparative bioinformatic analysis of genome-wide response patterns of human monocytes to MRP8, endotoxins, and various cytokines, we have developed a model in which TLR4 is the dominant receptor for MRP8-mediated phagocyte activation. The relevance of the TLR4 signaling pathway was experimentally validated using human and murine models of TLR4- and receptor for advanced glycation end products-dependent signaling. Furthermore, our systems biology approach has uncovered an antiapoptotic role for MRP8 in monocytes, which was corroborated by independent functional experiments. Our data confirm the primary importance of the TLR4/MRP8 axis in the activation of human monocytes, representing a novel and attractive target for modulation of the overwhelming innate immune response.

Ear2 deletion causes early memory and learning deficits in APP/PS1 mice.

To assess the consequences of locus ceruleus (LC) degeneration and subsequent noradrenaline (NA) deficiency in early Alzheimer's disease (AD), mice overexpressing mutant amyloid precursor protein and presenilin-1 (APP/PS1) were crossed with Ear2(-/-) mice that have a severe loss of LC neurons projecting to the hippocampus and neocortex. Testing spatial memory and hippocampal long-term potentiation revealed an impairment in APP/PS1 Ear2(-/-) mice, whereas APP/PS1 or Ear2(-/-) mice showed only minor changes. These deficits were associated with distinct synaptic changes including reduced expression of the NMDA 2A subunit and increased levels of NMDA receptor 2B in APP/PS1 Ear2(-/-) mice. Acute pharmacological replacement of NA by L-threo-DOPS partially restored phosphorylation of ß-CaMKII and spatial memory performance in APP/PS1 Ear2(-/-) mice. These changes were not accompanied by altered APP processing or amyloid ß peptide (Aß) deposition. Thus, early LC degeneration and subsequent NA reduction may contribute to cognitive deficits via CaMKII and NMDA receptor dysfunction independent of Aß and suggests that NA supplementation could be beneficial in treating AD.

Transcriptional adaptations during long-term persistence of Staphylococcus aureus in the airways of a cystic fibrosis patient.

The lungs of Cystic fibrosis (CF) patients are often colonized and/or infected by Staphylococcus aureus for years, mostly by one predominant clone. For long-term survival in this environment, S. aureus needs to adapt during its interactions with host factors, antibiotics, and other pathogens. Here, we study long-term transcriptional as well as genomic adaptations of an isogenic pair of S. aureus isolates from a single patient using RNA sequencing (RNA-Seq) and whole genome sequencing (WGS). Mimicking in vivo conditions, we cultivated the S. aureus isolates using artificial sputum medium before harvesting RNA for subsequent analysis. We confirmed our RNA-Seq data using quantitative real-time (qRT)-PCR and additionally investigated intermediate isolates from the same patient representing in total 13.2 years of persistence in the CF airways. Comparative RNA-Seq analysis of the first and the last ("late") isolate revealed significant differences in the late isolate after 13.2 years of persistence. Of the 2545 genes expressed in both isolates that were cultivated aerobically, 256 genes were up- and 161 were down-regulated with a minimum 2-fold change (2f). Focusing on 25 highly (≥8f) up- (n=9) or down- (n=16) regulated genes, we identified several genes encoding for virulence factors involved in immune evasion, bacterial spread or secretion (e.g. spa, sak, and esxA). Moreover, these genes displayed similar expression trends under aerobic, microaerophilic and anaerobic conditions. Further qRT-PCR-experiments of highly up- or down-regulated genes within intermediate S. aureus isolates resulted in different gene expression patterns over the years. Using sequencing analysis of the differently expressed genes and their upstream regions in the late S. aureus isolate resulted in only few genomic alterations. Comparative transcriptomic analysis revealed adaptive changes affecting mainly genes involved in host-pathogen interaction. Although the underlying mechanisms were not known, our results suggest adaptive processes beyond genomic mutations triggered by local factors rather than by activation of global regulators.

DNA methylation changes are a late event in acute promyelocytic leukemia and coincide with loss of transcription factor binding.

The origin of aberrant DNA methylation in cancer remains largely unknown. In the present study, we elucidated the DNA methylome in primary acute promyelocytic leukemia (APL) and the role of promyelocytic leukemia-retinoic acid receptor α (PML-RARα) in establishing these patterns. Cells from APL patients showed increased genome-wide DNA methylation with higher variability than healthy CD34(+) cells, promyelocytes, and remission BM cells. A core set of differentially methylated regions in APL was identified. Age at diagnosis, Sanz score, and Flt3-mutation status characterized methylation subtypes. Transcription factor-binding sites (eg, the c-myc-binding sites) were associated with low methylation. However, SUZ12- and REST-binding sites identified in embryonic stem cells were preferentially DNA hypermethylated in APL cells. Unexpectedly, PML-RARα-binding sites were also protected from aberrant DNA methylation in APL cells. Consistent with this, myeloid cells from preleukemic PML-RARα knock-in mice did not show altered DNA methylation and the expression of PML-RARα in hematopoietic progenitor cells prevented differentiation without affecting DNA methylation. Treatment of APL blasts with all-trans retinoic acid also did not result in immediate DNA methylation changes. The results of the present study suggest that aberrant DNA methylation is associated with leukemia phenotype but is not required for PML-RARα-mediated initiation of leukemogenesis.

A genome-wide association study identifies 6p21 as novel risk locus for dilated cardiomyopathy.

AIMS: Dilated cardiomyopathy (DCM) is one of the leading causes for cardiac transplantations and accounts for up to one-third of all heart failure cases. Since extrinsic and monogenic causes explain only a fraction of all cases, common genetic variants are suspected to contribute to the pathogenesis of DCM, its age of onset, and clinical progression. By a large-scale case-control genome-wide association study we aimed here to identify novel genetic risk loci for DCM. METHODS AND RESULTS: Applying a three-staged study design, we analysed more than 4100 DCM cases and 7600 controls. We identified and successfully replicated multiple single nucleotide polymorphism on chromosome 6p21. In the combined analysis, the most significant association signal was obtained for rs9262636 (P = 4.90 × 10(-9)) located in HCG22, which could again be replicated in an independent cohort. Taking advantage of expression quantitative trait loci (eQTL) as molecular phenotypes, we identified rs9262636 as an eQTL for several closely located genes encoding class I and class II major histocompatibility complex heavy chain receptors. CONCLUSION: The present study reveals a novel genetic susceptibility locus that clearly underlines the role of genetically driven, inflammatory processes in the pathogenesis of idiopathic DCM.

Phylogeny and phenotypes of clinical and environmental Shiga toxin-producing Escherichia coli O174.

Shiga toxin (Stx)-producing Escherichia coli (STEC) of serogroup O174 are human pathogenic intimin gene (eae)-negative STEC. To facilitate diagnosis and subtyping, we genotypically and phenotypically characterized 25 STEC O174 isolates from humans with different clinical outcomes and from animals and the environment. fliC genotyping resulted in four different genotypes (fliCH2 : n = 5; fliCH8 : n = 8; fliCH21 : n = 11; fliCH46 : n = 1). Twenty-three strains were motile expressing the corresponding H antigen; two non-motile isolates possessed fliCH8 . The stx genotypes and non-stx virulence loci, including toxins, serine-proteases and adhesins correlated well with serotypes but showed no differences with respect to the isolates' origins. Multilocus sequence typing identified seven sequence types that correlated with serotypes. Core gene typing further specified the four serotypes, including a previously unknown O174:H46 combination, and revealed distant relationships of the different serotypes within serogroup O174 and in relation to other haemolytic uremic syndrome (HUS)-associated STEC. Only serotype O174:H21 was associated with HUS. Differences in virulence factors and in the adherence capacity of STEC O174 corroborated this separation into four distinct groups. Our study provides a basis for O174 subtyping, unravels considerable genotypic and phenotypic heterogeneity and sheds light to potential environmental and animal reservoirs.

Bacterial whole-genome sequencing revisited: portable, scalable, and standardized analysis for typing and detection of virulence and antibiotic resistance genes.

Multidrug-resistant nosocomial pathogens present a major burden for hospitals. Rapid cluster identification and pathogen profiling, i.e., of antibiotic resistance and virulence genes, are crucial for effective infection control. Methicillin-resistant Staphylococcus aureus (MRSA), in particular, is now one of the leading causes of nosocomial infections. In this study, whole-genome sequencing (WGS) was applied retrospectively to an unusual spike in MRSA cases in two intensive care units (ICUs) over the course of 4 weeks. While the epidemiological investigation concluded that there were two separate clusters, each associated with one ICU, S. aureus protein A gene (spa) typing data suggested that they belonged to single clonal cluster (all cases shared spa type t001). Standardized gene sets were used to extract an allele-based profile for typing and an antibiotic resistance and toxin gene profile. The WGS results produced high-resolution allelic profiles, which were used to discriminate the MRSA clusters, corroborating the epidemiological investigation and identifying previously unsuspected transmission events. The antibiotic resistance profile was in agreement with the original clinical laboratory susceptibility profile, and the toxin profile provided additional, previously unknown information. WGS coupled with allelic profiling provided a high-resolution method that can be implemented as regular screening for effective infection control.

Paradoxical effects on force generation after efficient ß1-adrenoceptor knockdown in reconstituted heart tissue.

Stimulation of myocardial ß(1)-adrenoceptors (AR) is a major mechanism that increases cardiac function. We investigated the functional consequences of genetic ß(1)-AR knockdown in three-dimensional engineered heart tissue (EHT). For ß(1)-AR knockdown, short interfering RNA (siRNA) sequences targeting specifically the ß(1)-AR (shB1) and a scrambled control (shCTR) were subcloned into a recombinant adeno-associated virus (AAV)-short hairpin RNA (shRNA) expression system. Transduction efficiency was ∼100%, and radioligand binding revealed 70% lower ß(1)-AR density in AAV6-shB1-transduced EHTs. Force measurements, performed over the culture period of 14 days, showed paradoxically higher force generation in AAV6-shB1 compared with shCTR under basal (0.19 ± 0.01 versus 0.13 ± 0.01 mN) and after ß-AR-stimulated conditions with isoprenaline (Δfractional shortening: 72 ± 5% versus 34 ± 4%). Large scale gene expression analysis revealed that AAV6-shCTR compared with nontransduced EHTs showed only few differentially regulated genes (<20), whereas AAV6-shB1 induced marked changes in gene expression (>250 genes), indicating that ß(1)-AR knockdown itself determines the outcome. None of the regulated genes pointed to obvious off-target effects to explain higher force generation. Moreover, compensational regulation of ß(2)-AR signaling or changes in prominent ß(1)-AR downstream targets could be ruled out. In summary, we show paradoxically higher force generation and isoprenaline responses after efficient ß(1)-AR knockdown in EHTs. Our findings 1) reveal an unexpected layer of complexity in gene regulation after specific ß(1)-AR knockdown rather than unspecific dysregulations through transcriptional interference, 2) challenge classic assumptions on the role of cardiac ß(1)-AR, and 3) may open up new avenues for ß-AR loss-of-function research in vivo.

A genome-wide association study identifies a gene network of ADAMTS genes in the predisposition to pediatric stroke.

Pediatric stroke is a rare but highly penetrant disease with a strong genetic background. Although there are an increasing number of genome-wide association studies (GWASs) for stroke in adults, such studies for stroke of pediatric onset are lacking. Here we report the results of the first GWAS on pediatric stroke using a large cohort of 270 family-based trios. GWAS was performed using the Illumina 370 CNV single nucleotide polymorphisms array and analyzed using the transmission disequilibrium test as implemented in PLINK. An enrichment analysis was performed to identify additional true association signals among lower P value signals and searched for cumulatively associated genes within protein interaction data using dmGWAS. We observed clustering of association signals in 4 genes belonging to one family of metalloproteinases at high (ADAMTS12, P = 2.9 × 10(-6); ADAMTS2, P = 8.0 × 10(-6)) and moderate (ADAMTS13, P = 9.3 × 10(-4); ADAMTS17, P = 8.5 × 10(-4)) significance levels. Over-representation and gene-network analyses highlight the importance of the extracellular matrix in conjunction with members of the phosphoinositide and calcium signaling pathways in the susceptibility for pediatric stroke. Associated extracellular matrix components, such as ADAMTS proteins, in combination with misbalanced coagulation signals as unveiled by gene network analysis suggest a major role of postnatal vascular injury with subsequent thrombus formation as the leading cause of pediatric stroke.