Targeting the High-Density Lipoprotein Proteome for the Treatment of Post-Acute Sequelae of SARS-CoV-2

Here, we target the high-density lipoprotein (HDL) proteome in a case series of 16 patients with post-COVID-19 symptoms treated with HMG-Co-A reductase inhibitors (statin) plus angiotensin II type 1 receptor blockers (ARBs) for 6 weeks. Patients suffering from persistent symptoms (post-acute sequelae) after serologically confirmed SARS-CoV-2 infection (post-COVID-19 syndrome, PCS, n = 8) or following SARS-CoV-2 vaccination (PVS, n = 8) were included. Asymptomatic subjects with corresponding serological findings served as healthy controls (n = 8/8). HDL was isolated using dextran sulfate precipitation and the HDL proteome of all study participants was analyzed quantitatively by mass spectrometry. Clinical symptoms were assessed using questionnaires before and after therapy. The inflammatory potential of the patients' HDL proteome was addressed in human endothelial cells. The HDL proteome of patients with PCS and PVS showed no significant differences; however, compared to controls, the HDL from PVS/PCS patients displayed significant alterations involving hemoglobin, cytoskeletal proteins (MYL6, TLN1, PARVB, TPM4, FLNA), and amyloid precursor protein. Gene Ontology Biological Process (GOBP) enrichment analysis identified hemostasis, peptidase, and lipoprotein regulation pathways to be involved. Treatment of PVS/PCS patients with statins plus ARBs improved the patients' clinical symptoms. After therapy, three proteins were significantly increased (FAM3C, AT6AP2, ADAM10; FDR < 0.05) in the HDL proteome from patients with PVS/PCS. Exposure of human endothelial cells with the HDL proteome from treated PVS/PCS patients revealed reduced inflammatory cytokine and adhesion molecule expression. Thus, HDL proteome analysis from PVS/PCS patients enables a deeper insight into the underlying disease mechanisms, pointing to significant involvement in metabolic and signaling disturbances. Treatment with statins plus ARBs improved clinical symptoms and reduced the inflammatory potential of the HDL proteome. These observations may guide future therapeutic strategies for PVS/PCS patients.

The ratio of cytochrome c oxidase subunit 4 isoform 4I1 and 4I2 mRNA is changed in permanent atrial fibrillation

AIMS

The conditions of hypoxia are suggested to induce permanent atrial fibrillation (AF). The regulation of COX4I2 and COX4I1 depends on oxygen availability in tissues. A role of COX4I2 in the myocardium of AF patients is supposed for pathogenesis of AF and subsequent alterations in the electron transfer chain (ETC) under hypoxia.

METHODS AND RESULTS

In vitro, influence of hypoxia on HeLa 53 cells was studied and elevated parts of COX 4I2 were confirmed. Myocardial biopsies were taken ex vivo from the patients' Right Atria with SR (n = 31) and AF (n = 11), respectively. RT- PCR for mRNA expresson, mitochondrial respiration by polarography and the protein content of cytochrome c oxidase (CytOx) subunit 4I1 and CytOx subunit 4I2 by ELISA were studied. Clinical data were correlated to the findings of gene expressions in parallel. Patients with permanent AF had a change in isoform 4I2/4I1 expression along with a decrease of isoform COX 4I1 expression. The 4I2/4I1 ratio of mRNA expression was increased from 0.630 to 1.058 in comparison. However, the protein content of CytOx subunit 4 was much lower in the AF group, whereas the respiration/units enzyme activity in both groups remained the same.

CONCLUSIONS

This study describes a possible molecular correlate for the development of AF. Due to the known functional significance of COX 4I2, mitochondrial dysfunction can be assumed as a part of the pathogenesis of AF.

Comparative analysis of full-length 16s ribosomal RNA genome sequencing in human fecal samples using primer sets with different degrees of degeneracy

Next-generation sequencing has revolutionized the field of microbiology research and greatly expanded our knowledge of complex bacterial communities. Nanopore sequencing provides distinct advantages, combining cost-effectiveness, ease of use, high throughput, and high taxonomic resolution through its ability to process long amplicons, such as the entire 16s rRNA genome. We examine the performance of the conventional 27F primer (27F-I) included in the 16S Barcoding Kit distributed by Oxford Nanopore Technologies (ONT) and that of a more degenerate 27F primer (27F-II) in the context of highly complex bacterial communities in 73 human fecal samples. The results show striking differences in both taxonomic diversity and relative abundance of a substantial number of taxa between the two primer sets. Primer 27F-I reveals a significantly lower biodiversity and, for example, at the taxonomic level of the phyla, a dominance of Firmicutes and Proteobacteria as determined by relative abundances, as well as an unusually high ratio of Firmicutes/Bacteriodetes when compared to the more degenerate primer set (27F-II). Considering the findings in the context of the gut microbiomes common in Western industrial societies, as reported in the American Gut Project, the more degenerate primer set (27F-II) reflects the composition and diversity of the fecal microbiome significantly better than the 27F-I primer. This study provides a fundamentally relevant comparative analysis of the in situ performance of two primer sets designed for sequencing of the entire 16s rRNA genome and suggests that the more degenerate primer set (27F-II) should be preferred for nanopore sequencing-based analyses of the human fecal microbiome.

Fast and Easy Nanopore Sequencing Workflow for Rapid Genetic Testing of Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant lipid metabolism disorder characterized by severely elevated plasma low-density lipoprotein cholesterol levels. The disease is caused by mutations in 3 genes (LDLR, APOB and PCSK9) while over 90% of the mutations are located within the LDLR gene. Thus, genetic analysis of the LDLR gene is the first step in the genetic diagnosis of FH. However, conventional methods like Sanger and NextGen sequencing are still costly and time-consuming. In contrast, Oxford Nanopore technology sequencing is an emerging third-generation sequencing technology featured by easy operability, low cost, small size and the capability of parallel sample sequencing. Here, we present an easy Nanopore-sequencing-based workflow for the rapid genetic testing of FH taking only 3 days and costing less than $50 per sample without the requirement for deep bioinformatic knowledge. Using our workflow, we were able to identify the underlying pathogenic variants of 10 FH patients including one novel, not yet recorded pathogenic variants. Our workflow allows the rapid evaluation of the pathogenic variants by utilizing detailed variant information from Ensembl. Additionally, our workflow is not restricted to sequencing the LDLR gene alone but can be easily adapted to the other FH-causing genes and more importantly, to any desired gene contributing to any hereditary disease. Therefore, our workflow is an attractive opportunity for every diagnostic laboratory to offer fast and easy in-house genetic diagnostics.

Genome-wide association analysis in dilated cardiomyopathy reveals two new players in systolic heart failure on chromosomes 3p25.1 and 22q11.23

AIMS

Our objective was to better understand the genetic bases of dilated cardiomyopathy (DCM), a leading cause of systolic heart failure.

METHODS AND RESULTS

We conducted the largest genome-wide association study performed so far in DCM, with 2719 cases and 4440 controls in the discovery population. We identified and replicated two new DCM-associated loci on chromosome 3p25.1 [lead single-nucleotide polymorphism (SNP) rs62232870, P = 8.7 × 10-11 and 7.7 × 10-4 in the discovery and replication steps, respectively] and chromosome 22q11.23 (lead SNP rs7284877, P = 3.3 × 10-8 and 1.4 × 10-3 in the discovery and replication steps, respectively), while confirming two previously identified DCM loci on chromosomes 10 and 1, BAG3 and HSPB7. A genetic risk score constructed from the number of risk alleles at these four DCM loci revealed a 3-fold increased risk of DCM for individuals with 8 risk alleles compared to individuals with 5 risk alleles (median of the referral population). In silico annotation and functional 4C-sequencing analyses on iPSC-derived cardiomyocytes identify SLC6A6 as the most likely DCM gene at the 3p25.1 locus. This gene encodes a taurine transporter whose involvement in myocardial dysfunction and DCM is supported by numerous observations in humans and animals. At the 22q11.23 locus, in silico and data mining annotations, and to a lesser extent functional analysis, strongly suggest SMARCB1 as the candidate culprit gene.

CONCLUSION

This study provides a better understanding of the genetic architecture of DCM and sheds light on novel biological pathways underlying heart failure.

Deficiency of Nucleotide-binding oligomerization domain-containing proteins (NOD) 1 and 2 reduces atherosclerosis

Atherosclerosis is crucially fueled by inflammatory pathways including pattern recognition receptor (PRR)-related signaling of the innate immune system. Currently, the impact of the cytoplasmic PRRs nucleotide-binding oligomerization domain-containing protein (NOD) 1 and 2 is incompletely characterized. We, therefore, generated Nod1/Nod2 double knockout mice on a low-density lipoprotein receptor (Ldlr)-deficient background (= Ldlr^−/−Nod1/2^−/−) which were subsequently analyzed regarding experimental atherosclerosis, lipid metabolism, insulin resistance and gut microbiota composition. Compared to Ldlr^−/− mice, Ldlr^−/−Nod1/2^−/− mice showed reduced plasma lipids and increased hepatic expression of the scavenger receptor LDL receptor-related protein 1 after feeding a high-fat diet for 12 weeks. Furthermore, intestinal cholesterol and its bacterial degradation product coprostanol were elevated in Ldlr^−/−Nod1/2^−/− mice, correlating with the increased abundance of Eubacterium coprostanoligenes as assessed by 3rd generation sequencing of the gut microbiota. Atherosclerotic plaques of Ldlr^−/−Nod1/2^−/− mice exhibited less lipid deposition and macrophage accumulation. Moreover, macrophages from Ldlr^−/−Nod1/2^−/− mice showed higher expression of the cholesterol efflux transporters Abca1 and Abcg1 and accordingly reduced foam cell formation. Deficiency of Nod1 and Nod2 led to reduced plaque lipid deposition and inflammatory cell infiltration in atherosclerotic plaques. This might be explained by diminished plasma lipid levels and foam cell formation due to altered expression of key regulators of the hepatic cholesterol pathway as well as differential intestinal cholesterol metabolism and microbiota composition.

Mitochondrial active and relaxed state respiration after heat shock mRNA response in the heart

Induction of Heat Shock Proteins results in cytoprotection. Beneficial effect results from transcription and translational cellular components' involvement that defends metabolism and thus induce ischemic protection of the tissue. Mitochondrial respiration is also involved in stress- induced conditions. It is not a uniform process. Cytochrome c Oxidase (CytOx) representing complex IV of the Electron Transfer Chain (ETC) has a regulatory role for mitochondrial respiratory activity, which is tested in our study after hsp induction. Moreover, protein translation for mitochondrial components was probed by the detection of MT-CO1 for Subunit 1 of CytOx neosynthesis. Wistar rats were subjected to whole-body hyperthermia at 42.0-42.5 °C for 15 min followed by a normothermic recovery period. Heat shock response was monitored time dependent from LV biopsies of all control and heat treated animals with PCR-analysis for hsp 32, 60, 70.1, 70.2, 90 and MT-CO1 expression at 15, 30, 45, 60, 120 and 360 min recovery (n = 5 in each group), respectively. Enzymatic activity of CytOx were evaluated polarographically. High energy phosphates were detected by chromatographic analysis. The mRNA expression of MT-CO1 peaked at 60 min and was accompanied by hsp 32 (r = 0.457; p = 0.037) and hsp 70.2 (r = 0.615; p = 0.003) upregulation. With hsp induction, mitochondrial respiration was increased initially. Enzymatic activity reconciled from active into relaxed status wherein CytOx activity was completely inhibited by ATP. Myocardial ATP content increased from stress induced point i.e. < 1 µmol g^-1 protein w/w to finally 1.5 ± 0.53 µmol g^-1 protein w/w at 120 min recovery interval. Hyperthermic, myocardial hsp- induction goes along with increased CytOx activity representing an increased "active" mitochondrial respiration. In parallel, de -novo holoenzyme assembly of CytOx begins as shown by MT-CO1 upregulation at 60 min recovery time crossing with a final return to the physiological "relaxed" state and ATP -inhibited respiration.

Increased KCNJ18 promoter activity as a mechanism in atypical normokalemic periodic paralysis

Objective

To identify the genetic basis of a patient with symptoms of normokalemic sporadic periodic paralysis (PP) and to study the effect of KCNJ18 mutations.

Methods

A candidate gene approach was used to identify causative gene mutations, using Sanger sequencing. KCNJ18 promoter activity was analyzed in transfected HEK293 cells with a luciferase assay, and functional analysis of Kir2.6 channels was performed with the two-electrode voltage-clamp technique.

Results

Although we did not identify harmful mutations in SCN4A, CACNA1S, KCNJ2 and KCNE3, we detected a monoallelic four-fold variant in KCNJ18 (R39Q/R40H/A56E/I249V), together with a variant in the respective promoter of this channel (c.-542T/A). The exonic variants in Kir2.6 did not alter the channel function; however, luciferase assays revealed a 10-fold higher promoter activity of the c.-542A promoter construct, which is likely to cause a gain-of-function by increased expression of Kir2.6. We found that reducing extracellular K⁺ levels causes a paradoxical reduction in outward currents, similar to that described for other inward rectifying K⁺ channels. Thus, reducing the extracellular K⁺ levels might be a therapeutic strategy to antagonize the transcriptionally increased KCNJ18 currents. Consistently, treatment of the patient with K⁺ reducing drugs dramatically improved the health situation and prevented PP attacks.

Conclusions

We show that a promoter defect in the KCNJ18 gene is likely to cause periodic paralysis, as the observed transcriptional upregulation will be linked to increased Kir2.6 function. This concept is further supported by our observation that most of the PP attacks in our patient disappeared on medical treatment with K⁺ reducing drugs.

Myocardial insufficiency is related to reduced subunit 4 content of cytochrome c oxidase

BACKGROUND

Treatment of heart failure remains one of the most challenging task for intensive care medicine, cardiology and cardiac surgery. New options and better indicators are always required. Understanding the basic mechanisms underlying heart failure promote the development of adjusted therapy e.g. assist devices and monitoring of recovery. If cardiac failure is related to compromised cellular respiration of the heart, remains unclear. Myocardial respiration depends on Cytochrome c- Oxidase (CytOx) activity representing the rate limiting step for the mitochondrial respiratory chain. The enzymatic activity as well as mRNA expression of enzyme's mitochondrial encoded catalytic subunit 2, nuclear encoded regulatory subunit 4 and protein contents were studied in biopsies of cardiac patients suffering from myocardial insufficiency and dilated cardiomyopathy (DCM).

METHODS

Fifty-four patients were enrolled in the study and underwent coronary angiography. Thirty male patients (mean age: 45 +/- 15 yrs.) had a reduced ejection fraction (EF) 35 ± 12% below 45% and a left ventricular end diastolic diameter (LVEDD) of 71 ± 10 mm bigger than 56 mm. They were diagnosed as having idiopathic dilated cardiomyopathy (DCM) without coronary heart disease and NYHA-class 3 and 4. Additionally, 24 male patients (mean age: 52 +/- 11 yrs.) after exclusion of secondary cardiomyopathies, coronary artery or valve disease, served as control (EF: 68 ± 7, LVEDD: 51 ± 7 mm). Total RNA was extracted from two biopsies of each person. Real-time PCR analysis was performed with specific primers followed by a melt curve analysis. Corresponding protein expression in the tissue was studied with immune-histochemistry while enzymatic activity was evaluated by spectroscopy.

RESULTS

Gene and protein expression analysis of patients showed a significant decrease of subunit 4 (1.1 vs. 0.6, p < 0.001; 7.7 ± 3.1% vs. 2.8 ± 1.4%, p < 0.0001) but no differences in subunit 2. Correlations were found between reduced subunit 2 expression, low EF (r = 0.766, p < 0.00045) and increased LVEDD (r = 0.492, p < 0.0068). In case of DCM less subunit 4 expression and reduced shortening fraction (r = 0.524, p < 0.017) was found, but enzymatic activity was higher (0.08 ± 0.06 vs. 0.26 ± 0.08 U/mg, p < 0.001) although myocardial oxygen consumption continued to the same extent.

CONCLUSION

In case of myocardial insufficiency and DCM, decreased expression of COX 4 results in an impaired CytOx activity. Higher enzymatic activity but equal oxygen consumption contribute to the pathophysiology of the myocardial insufficiency and appears as an indicator of oxidative stress. This kind of dysregulation should be in the focus for the development of diagnostic and therapy procedures.

The prognostic value of sST2 and galectin-3 considering different aetiologies in non-ischaemic heart failure

Objective

Several studies indicate a prognostic value of sST2 and galectin-3 in heart failure (HF). While previous studies focused on ischaemic cause of HF, we investigated the role of sST2 and galectin-3 in patients with non-ischaemic dilated cardiomyopathy (DCM).

Methods

sST2 and galectin-3 serum concentrations were measured in 262 subjects with DCM. Survival rates were determined for all-cause mortality (ACM) and cardiac mortality (CM).

Results

In a univariate model, sST2 as a continuous variable was a predictor of ACM (HR 1.05; 95% CI 1.03 to 1.07, P<0.001) and CM (HR 1.03; 95% CI 1.00 to 1.06, P=0.040). In the subgroup of patients with inflammatory and/or viral DCM (DCMi⋎viral), the endpoints ACM (HR 1.10; 95% CI 1.05 to 1.17, P<0.001) and CM (HR 1.10; 95% CI 1.02 to 1.18, P=0.013) were significant. In the subgroup of patients with idiopathic DCM, the endpoint ACM (HR 1.04; 95% CI 1.01 to 1.07, P=0.019) was significant. In a multivariate model, the prognostic value of the sST2 main group remained intact for ACM (HR 1.04; 95% CI 1.02 to 1.07, P=0.003).

Univariate and multivariate analysis of galectin-3 as continuous variable did not show any significant result. However, in a quartile model, intermediate values of galectin-3 were significantly associated with a lower event rate of ACM and CM.

Conclusion

The study revealed that sST2 predicts ACM and CM in patients with non-ischaemic HF and could be useful especially in patients with inflammatory background. Our findings that intermediate levels of galectin-3 allow for better prognosis were new and different to other investigations.

Trial registration number

NCT03090425; Results.

Double Tube Stent-Grafts for Infrarenal Aortic Aneurysm: A New Concept

Purpose:

To present the concept of double tube stent-grafts and examine the indications for and results achieved with these devices.

Methods:

From January 1, 2000, to December 31, 2005, 759 patients who underwent endovascular repair of infrarenal aortic aneurysms at 2 centers. Of these, 45 (5.9%) patients received a double tube stent-graft; complete operative and follow-up data were available for retrospective analysis in 41 patients (33 men; mean age 73.1±8.9 years). Diameters measured before stent-graft implantation and at follow-up (12, 24, 36, and 48 months) with clinical examination, 2-phase computed tomographic angiography, duplex sonography, and biplanar abdominal radiography were tested for significant changes using ANOVA with the Bonferroni-Dunn correction. Late outcomes (clinical success and endoleak) were analyzed by the Kaplan-Meier method.

Results:

The postoperative complication rate was 12.2%, with 2.4% systemic complications (1 patient with angina pectoris); the early mortality rate was 0%. Mean follow-up was 21.9±12.8 months (range 12–61) for the 41 patients. Four (9.8%) patients died during follow-up of cardiac causes (n=2), lung cancer (n=1), and bowel ischemia (n=1). Four (9.8%) endoleaks were observed during follow-up: 1 distal type I, 2 type II, and 1 type III. Maximum aneurysm diameters shrank from 52.0±9.5 mm preoperatively to 44.0±10.8 mm (p<0.0001) postoperatively at the latest available follow-up.

Conclusion:

Our study supports the use of this double tube technique for repair of appropriate saccular infrarenal aortic aneurysms. The double tube stent-graft method appears safe in terms of endoleaks and migration, so we recommend that it be considered an option of endovascular aortic aneurysm therapy.

Influence of different aetiologies on clinical course and outcome in patients with dilated cardiomyopathy

BACKGROUND

The clinical phenotype dilated cardiomyopathy is assumed to be the endstage of a multifactorial aetiopathogenetic pathophysiology which includes a not satisfactorily defined group of patients with inflammatory cardiomyopathy.

METHODS

Within the German Competence Network Heart Failure patients with heart failure due to dilated cardiomyopathy of viral/inflammatory (DCMi/v) and nonviral/noninflammatory (DCM) aetiology were enrolled. After 1 year 237 patients (180 male/57 female) were re-examined including complete clinical work-up. The association of different clinical courses with the time from initial diagnosis of heart failure (newly: ≤ 1 year; late: > 1 year) was investigated.

RESULTS

After 1-year-follow-up New York Heart Association (NYHA) class (by -0.48 in newly diagnosed DCM and -0.82 in newly diagnosed DCMi/v in addition to -0.24 in late diagnosed DCM and -0.17 in late diagnosed DCMi/v) as well as left ventricular ejection fraction (+14% in newly diagnosed DCM and DCMi/v and +6% in later diagnosed DCM and DCMi/v) were significantly improved in all patients. In patients with early diagnosed dilated cardiomyopathy a strong improvement of NYHA class could be demonstrated.

CONCLUSIONS

This study demonstrates for the first time a significant interaction between duration of disease, NYHA class and left ventricular ejection fraction in patients with DCM. Our results clearly demonstrate that in patients with DCM an early diagnosis within 1 year after occurrence of clinical signs is associated with a strong improvement in the clinical course, whereas late diagnosis results in a loss of change in clinical course and outcome.

Management of fulminant myocarditis: a diagnosis in search of its etiology but with therapeutic options

Fulminant myocarditis is a clinical syndrome with signs of acute heart failure, cardiogenic shock, or life-threating rhythm disturbances in the context of suspected myocarditis. It is not an etiological diagnosis, but may have different underlying causes and pathogenetic processes - viral, bacterial, toxic, and autoreactive. Clinical management of the disease entity at the acute stage involves hemodynamic monitoring in an intensive care unit or similar setting. Rapid routine work-up is mandatory with serial EKGs, echocardiography, cardiac MRI, heart catheterization with endomyocardial biopsy for histology, immunohistology, and molecular analysis for the underlying infection and pathogenesis. Heart failure therapy is warranted in all cases according to current guidelines. For fulminant autoreactive myocarditis, immunosuppressive treatment is beneficial; for viral myocarditis, IVIg can resolve the inflammation, reduce the viral load, and even eradicate the microbial agent. ECMO, IABP, ventricular assist devices, LifeVest, or ICD implantation can bridge to recovery or to heart transplantation.

Trypanosoma cruzi evades the protective role of interferon-gamma-signaling in parasite-infected cells

The protozoan parasite Trypanosoma cruzi is responsible for the zoonotic Chagas disease, a chronic and systemic infection in humans and warm-blooded animals typically leading to progressive dilated cardiomyopathy and gastrointestinal manifestations. In the present study, we report that the transcription factor STAT1 (signal transducer and activator of transcription 1) reduces the susceptibility of human cells to infection with T. cruzi. Our in vitro data demonstrate that interferon -γ (IFNγ) pre-treatment causes T. cruzi-infected cells to enter an anti-parasitic state through the activation of the transcription factor STAT1. Whereas stimulation of STAT1-expressing cells with IFNγ significantly impaired intracellular replication of parasites, no protective effect of IFNγ was observed in STAT1-deficient U3A cells. The gene encoding indoleamine 2, 3-dioxygenase (ido) was identified as a STAT1-regulated target gene engaged in parasite clearance. Exposure of cells to T. cruzi trypomastigotes in the absence of IFNγ resulted in both sustained tyrosine and serine phosphorylation of STAT1 and its increased DNA binding. Furthermore, we found that in response to T. cruzi the total amount of intracellular STAT1 increased in an infectious dose-dependent manner, both at the mRNA and protein level. While STAT1 activation is a potent strategy of the host in the fight against the invading pathogen, amastigotes replicating intracellularly antagonize this pathway by specifically promoting the dephosphorylation of STAT1 serine 727, thereby partially circumventing its protective effects. These findings point to the crucial role of the IFNγ/STAT1 signal pathway in the evolutionary combat between T. cruzi parasites and their host.

Influence of cyclical mechanical loading on osteogenic markers in an osteoblast-fibroblast co-culture in vitro: tendon-to-bone interface in anterior cruciate ligament reconstruction

PURPOSE

We aimed to evaluate the influence of cyclical mechanical loading on osteoblasts and fibroblasts, and co-cultures of both in vitro, simulating the conditions of the tendon-to-bone interface in anterior cruciate ligament reconstruction.

METHODS

Osteoblast-like cells (OBL) and tendon-derived rodent fibroblasts (TDF) were cultured alone or in co-culture to simulate the tendon-to-bone interface. Cyclical loading was applied for one hour twice a day for three days, with a frequency of 1 Hz and 3 % strain. Alkaline phosphatase (AP), osteocalcin (OC), collagen type 1 (COL1A1), and bone morphogenetic protein 2 (BMP-2) gene expression and protein deposition were detected by real-time polymerase chain reaction (qPCR) and immunocytochemical analysis.

RESULTS

Mechanical loading significantly decreased AP, OC, and COL1A1 gene expression in both OBL and TDF, compared to non-loaded culture. However, mechanical load increased gene expression of the same marker genes including BMP-2 during co-culture. Immunocytochemistry demonstrated increased deposition of corresponding proteins in the same range, independent of culture conditions. Higher depositions of BMP-2 were shown under loading conditions for osteoblast and TDF monocultures. Prolongation of mechanical loading resulted in cell detachment and spheroid formation.

CONCLUSION

Cyclical mechanical loading caused downregulation of genes involved in osteointegration and osteoinduction, such as OC, ALP, and COL1A1 in monocultures of osteoblasts and fibroblasts; co-cultures lacked this phenomenon. Immunocytochemistry and qPCR analysis showed slight upregulations of marker genes and corresponding proteins. This might be due to the potential stabilising effects of osteoblast-fibroblast cross talk in the co-culture environment, simulating fibrocartilage formation at the tendon-to-bone interface.

Viral genomes in the pericardial fluid and in peri- and epicardial biopsies from a German cohort of patients with large to moderate pericardial effusions

The aetiology of pericardial effusion has been generally assessed by clinical work-up only, which leaves a large cohort of patients with "idiopathic" effusions virtually undiagnosed. In accordance with the ESC guidelines, this contribution intends to change this attitude. After therapeutic or diagnostic pericardiocentesis of 259 patients with large to moderate pericardial effusions, pericardial fluid, epicardial and pericardial biopsies, and blood samples were analysed by PCR for cardiotropic microbial agents. Cytology, histology, immunohistology of tissue and fluids and laboratory tests were performed. Of the 259 patients, 35 % suffered from an autoreactive aetiology, 28 % suffered from a malignant and 14 % from an infectious cause. Investigating all samples by PCR, we identified viral genomes in 51 (19.7 %) patients, parvovirus B19 (B19 V) being identified in 25 and Epstein-Barr virus (EBV) in 19 cases. In patients with a sole infectious aetiology (n = 36), B19 V was detected in 21 and EBV in 10 cases. When differentiating with regard to the material investigated for the presence of cardiotropic viruses, parvovirus B19 was most often detected in the epicardium and EBV was most frequently detected in the pericardial fluid independent from the final diagnostic categorisation. Bacterial cultures including tests for tuberculosis were all negative. Molecular techniques improve sensitivity, specificity and diagnostic accuracy for the underlying aetiology in pericarditis patients with effusion. The identification of specific viral signatures will help to understand pathogenetic mechanisms in pericarditis and allow to tailor an adequate therapy beyond antiphlogistic treatment.

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.

Detection of a large duplication mutation in the myosin-binding protein C3 gene in a case of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a cardiovascular disease with autosomal dominant inheritance caused by mutations in genes coding for sarcomeric and/or regulatory proteins expressed in cardiomyocytes. In a small cohort of HCM patients (n=8), we searched for mutations in the two most common genes responsible for HCM and found four missense mutations in the MYH7 gene encoding cardiac β-myosin heavy chain (R204H, M493V, R719W, and R870H) and three mutations in the myosin-binding protein C3 gene (MYBPC3) including one missense (A848V) and two frameshift mutations (c.3713delTG and c.702ins26bp). The c.702ins26bp insertion resulted from the duplication of a 26-bp fragment in a 54-year-old female HCM patient presenting with clinical signs of heart failure due to diastolic dysfunction. Although such large duplications (>10 bp) in the MYBPC3 gene are very rare and have been identified only in 4 families reported so far, the identical duplication mutation was found earlier in a Dutch patient, demonstrating that it may constitute a hitherto unknown founder mutation in central European populations. This observation underscores the significance of insertions into the coding sequence of the MYBPC3 gene for the development and pathogenesis of HCM.

Identification of a missense mutation in the melusin-encoding ITGB1BP2 gene in a patient with dilated cardiomyopathy

In a heterogeneous cohort of patients (n=255) with sporadic and familial dilated cardiomyopathy (DCM), we searched for novel disease-associated mutations in the human melusin-encoding ITGB1BP2 gene and found only one missense mutation, which was a substitution of alanine for glycine at position 313 located in the carboxy-terminal spacer region of the molecule. This point mutation (c.938C>G) was identified in a 45-year-old male with familial DCM and severe impairment of left-ventricular function, but was absent in 300 healthy control subjects. However, its functional significance in the context of heart failure is unclear, as this amino acid substitution was predicted to be without disease-causing effects. In this report, we confirm the low prevalence of mutations and single nucleotide polymorphisms in the coding sequence of the human melusin gene in patients with DCM, ruling out the possibility that genetic variations in this myocardially transcribed gene may have a significant impact on the epidemiology of DCM-induced heart failure.

Two glutamic acid residues in the DNA-binding domain are engaged in the release of STAT1 dimers from DNA

Background

In interferon-γ-stimulated cells, the dimeric transcription factor STAT1 (signal transducer and activator of transcription 1) recognizes semi-palindromic motifs in the promoter regions of cytokine-driven target genes termed GAS (gamma-activated sites). However, the molecular steps that facilitate GAS binding and the subsequent liberation of STAT1 homodimers from these promoter elements are not well understood.

Results

Using a mutational approach, we identified two critical glutamyl residues within the DNA-binding domain adjacent to the phosphodiester backbone of DNA which efficiently release phospho-STAT1 from DNA. The release of STAT1 dimers from DNA enhances transcriptional activity on both interferon-driven reporter and endogenous target genes. A substitution of either of the two glutamic acid residues broadens the repertoire of putative binding sites on DNA and enhances binding affinity to GAS sites. However, despite elevated levels of tyrosine phosphorylation and a prolonged nuclear accumulation period, the STAT1 DNA-binding mutants show a significantly reduced transcriptional activity upon stimulation of cells with interferon-γ. This reduced transcriptional response may be explained by the deposition of oligomerized STAT1 molecules outside GAS sites.

Conclusions

Thus, two negatively charged amino acid residues in the DNA-binding domain are engaged in the liberation of STAT1 from DNA, resulting in a high dissociation rate from non-GAS sites as a key feature of STAT1 signal transduction, which positively regulates cytokine-dependent gene expression probably by preventing retention at transcriptionally inert sites.

Genotype-specific effects on left ventricular function in parvovirus B19-positive patients with dilated cardiomyopathy

Genotype-specific effects of parvovirus B19 (B19V) infections on left ventricular function in patients with dilated cardiomyopathy (DCM) have not been investigated so far. In this prospective clinical study, the prevalences of B19V genotypes in endomyocardial biopsies from patients presenting with inflammatory heart disease and DCM were determined. A total of 139 consecutive patients were included in the study; among them 53 patients were diagnosed as DCM. Among the total study cohort, B19V DNA was detected in 65 study participants (46.8%). Genotyping of the B19V genomes in the total cohort identified genotype 1 in 38 samples (27.3%), genotype 2 in 25 samples (18.0%), and genotype 3 in only two patients (1.4%). During an average follow-up period of 8 months left ventricular ejection fraction (LVEF) improved significantly both in B19V-positive (7.1 ± 13.8%, n = 17, P = 0.038) as well as B19V-negative patients with DCM (9.5 ± 13.9%, n = 20, P = 0.017). However, mean LVEF improved only in patients with genotype 1 (11.0 ± 14.4%, n = 7), whereas it even decreased in patients with genotype 2 (-6.2 ± 6.3%, n = 5, P = 0.033). These data from a small sample of patients diagnosed as DCM suggested that myocardial function during short-time follow-up differed between genetic variants of B19V. Patients with genotype 1 were on average younger than genotype 2 and appeared to be more prone to a beneficial course of left ventricular function than patients with genotype 2. Future studies with larger sample sizes and longer follow-up periods will be required to confirm this observation.

A genome-wide association study identifies two loci associated with heart failure due to dilated cardiomyopathy

AIMS

Dilated cardiomyopathy (DCM) is a major cause of heart failure with a high familial recurrence risk. So far, the genetics of DCM remains largely unresolved. We conducted the first genome-wide association study (GWAS) to identify loci contributing to sporadic DCM.

METHODS AND RESULTS

One thousand one hundred and seventy-nine DCM patients and 1108 controls contributed to the discovery phase. Pools of DNA stratified on disease status, population, age, and gender were constituted and used for testing association of DCM with 517 382 single nucleotide polymorphisms (SNPs). Three DCM-associated SNPs were confirmed by individual genotyping (P < 5.0 10(-7)), and two of them, rs10927875 and rs2234962, were replicated in independent samples (1165 DCM patients and 1302 controls), with P-values of 0.002 and 0.009, respectively. rs10927875 maps to a region on chromosome 1p36.13 which encompasses several genes among which HSPB7 has been formerly suggested to be implicated in DCM. The second identified locus involves rs2234962, a non-synonymous SNP (c.T757C, p. C151R) located within the sequence of BAG3 on chromosome 10q26. To assess whether coding mutations of BAG3 might cause monogenic forms of the disease, we sequenced BAG3 exons in 168 independent index cases diagnosed with familial DCM and identified four truncating and two missense mutations. Each mutation was heterozygous, present in all genotyped relatives affected by the disease and absent in a control group of 347 healthy individuals, strongly suggesting that these mutations are causing the disease.

CONCLUSION

This GWAS identified two loci involved in sporadic DCM, one of them probably implicates BAG3. Our results show that rare mutations in BAG3 contribute to monogenic forms of the disease, while common variant(s) in the same gene are implicated in sporadic DCM.

Identification of mutational hot spots in LMNA encoding lamin A/C in patients with familial dilated cardiomyopathy

The familial form of dilated cardiomyopathy (DCM) occurs in about 20%-50% of DCM cases. It is a heterogeneous genetic disease: mutations in more than 20 different genes have been shown to cause familial DCM. LMNA, encoding the nuclear membrane protein lamin A/C, is one of the most important disease gene for that disease. Therefore, we analyzed the LMNA gene in a large cohort of 73 patients with familial DCM. Clinical examination (ECG, echocardiography, and catheterization) was followed by genetic characterization of LMNA by direct sequencing. We detected five heterozygous missense mutations (prevalence 7%) in five different families characterized by severe DCM and heart failure with conduction system disease necessitating pacemaker implantation and heart transplantation. Four of these variants clustered in the protein domain coil 1B, which is important for lamin B interaction and lamin A/C dimerization. Although we identified two novel mutations (E203V, K219T) besides three known ones (E161K, R190Q, R644C), it was remarkable that four mutations represent LMNA hot spots. DCM patients with LMNA mutations show a notable homogenous severe phenotype as we could confirm in our study. Testing LMNA in such families seems to be recommended because genotype information in an individual could definitely be useful for the clinician.

A missense variant in desmoglein-2 predisposes to dilated cardiomyopathy

Familial Dilated Cardiomyopathy (FDCM) is caused by mutations in genes encoding myocardial force transduction proteins. Desmoglein-2 (DSG2) and Desmocollin-2 (DSC2) provide cellular adhesion and force transduction by cell-to-cell anchorage. To test whether perturbations of DSG2 or DSC2 exhibit a pathogenic impact on DCM pathogenesis, we sequenced both genes in 73 patients with FDCM and assessed prevalence of missense variations in matched control cohorts. We detected two missense variations in DSG2 (V55M and V919G) which were absent in 360 control alleles. Surprisingly, both variants were previously reported in patients with arrhythmogenic right ventricular cardiomyopathy. Yet, in the present study only the DSG2-V55M variant showed segregation with DCM in a family pedigree. Subsequent, analysis of 538 patients with idiopathic DCM and 617 consecutive control individuals resulted in identification of thirteen DSG2-V55M carriers with DCM, whereas only three control subjects harbored the variant. DSG2 immunostaining revealed pale structures of the intercalated disc in myocardium of one unique homozygous DSG2-V55M carrier. Furthermore, myocardial desmosomal structures were significantly shortened when compared to DCM myocardium negative for DSG2-V55M. Thus, our study identified the DSG2-V55M polymorphism as a novel risk variant for DCM associated with shortened desmosomes of the cardiac intercalated disc.

Glycosylphosphatidylinositol-induced cardiac myocyte death might contribute to the fatal outcome of Plasmodium falciparum malaria

BACKGROUND

Glycosylphosphatidylinositol (GPI) purified from Plasmodium falciparum has been shown to play an important role as a toxin in the pathology of malaria. Previous studies demonstrated cardiac involvement in patients suffering from severe malaria due to P. falciparum. Therefore, we tested the hypothesis that GPI induces apoptosis in cardiomyocytes.

METHODS AND RESULTS

By using TUNEL and caspase activity assays, we provided evidence for apoptosis induction in cardiomyocytes by P. falciparum GPI after 48 h of incubation. A similar result was obtained in heart cells of mice 48 h after in vivo injection of GPI. Gene expression analyses in GPI-treated cardiomyocytes showed an up-regulation of apoptotic genes (apaf-1, bax) and of a myocardial damage marker bnp (brain natriuretic peptide), while a down-regulation was observed for the anti-apoptotic gene bcl-2 and for the heat shock protein hsp70. In spite of inflammatory cytokine gene up-regulation by GPI, co-culture with peripheral mononuclear cells (PMNCs) did not change the results obtained with cardiomyocytes alone, indicating a direct effect of GPI on cardiac myocytes. Co-culture with non-myocytic cardiac cells (NMCCs) resulted in up-regulation of Hsp70 and Bcl-2 genes in GPI-treated cardiomyocytes but without repercussion on the apoptosis level. A malaria-infected patient, presenting fulminant heart failure showed typical signs of cardiac myocyte apoptosis demonstrating the clinical relevance of toxin induced heart damage for the lethality of malaria. Our studies performed in vitro and in mice suggest that the GPI could be responsible for cardiomyocyte apoptosis that occurred in this patient.

CONCLUSION

Plasmodium falciparum GPI-induced apoptosis might participate in the lethality of malaria.

Hereditary long QT syndrome due to autoimmune hypoparathyroidism in autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), also known as autoimmune polyglandular syndrome type I, is a rare autosomal recessively inherited disorder characterized by variable combinations of endocrine and nonendocrine symptoms. In this report, we describe two 20- and 17-year-old Turkish siblings presenting with typical symptoms of APECED, including Addison disease, alopecia, vitiligo, and hypopituitarism, in whom electrocardiographic examinations demonstrated an abnormal prolongation of the QT interval. In both cases, excessive hypocalcemia due to primary hypoparathyroidism was identified as the underlying cause of the long QT syndrome. Sequencing the gene coding for the autoimmune regulator revealed a homozygous missense mutation in exon 14 with a C-to-T transition that resulted in the substitution of proline 539 for leucine in the carboxy-terminal protein molecule. Our data show that a single point mutation in the transcriptional active autoimmune regulator protein is associated with inherited alterations in calcium metabolism resulting from autoimmune reactions against the parathyroid glands. This finding defines a congenital autoimmune disease as a hereditary long QT syndrome.