Antigen-free control wells in an ELISA set-up for the determination of autoantibodies against G protein-coupled receptors-a requisite for correct data evaluation.

First functional acting autoantibodies against G protein-coupled receptors such as the beta2-adrenoceptor in e.g. asthmatic patients have already been discovered in the early 1980s of the last century using assays that show their functional activity. Today, almost 40 years later, the measurement of such autoantibodies is still a challenge. Bioassays able to show the functional activity of such autoantibodies against G protein-coupled receptors are still the ne plus ultra for their detection and also classification when additionally exploiting specific receptor blockers for the neutralisation of the effect. Bioassays based on living cells make specific demands on the laboratories and are, therefore not suitable for every routine laboratory. Routine diagnostics, therefore, ideally requires different assays based on e.g. solid-phase technology, such as enzyme-linked immunosorbent assay (ELISA) technology. Here, endeavours are going on, using either the exact epitopes of such autoantibodies, if known, for trapping the autoantibodies, or the complete receptor in biological or artificial membranes that are immobilised onto a plastic carrier (ELISA principle). Here, we question and discuss the outcome of such tests, especially, if no controls such as the non-coated plastic carrier or the corresponding receptor-free membrane coat is offered as control in parallel, in light of the manifold experiences already collected with even non-agonistic acting autoantibodies by Güven et al. (J Immunol Methods 403:26-36, 2014).

Critical illness myopathy and GLUT4: significance of insulin and muscle contraction.

RATIONALE: Critical illness myopathy (CIM) has no known cause and no treatment. Immobilization and impaired glucose metabolism are implicated. OBJECTIVES: We assessed signal transduction in skeletal muscle of patients at risk for CIM. We also investigated the effects of evoked muscle contraction. METHODS: In a prospective observational and interventional pilot study, we screened 874 mechanically ventilated patients with a sepsis-related organ-failure assessment score greater than or equal to 8 for 3 consecutive days in the first 5 days of intensive care unit stay. Thirty patients at risk for CIM underwent euglycemic-hyperinsulinemic clamp, muscle microdialysis studies, and muscle biopsies. Control subjects were healthy. In five additional patients at risk for CIM, we performed corresponding analyses after 12-day, daily, unilateral electrical muscle stimulation with the contralateral leg as control. MEASUREMENTS AND MAIN RESULTS: We performed successive muscle biopsies and assessed systemic insulin sensitivity and signal transduction pathways of glucose utilization at the mRNA and protein level and glucose transporter-4 (GLUT4) localization in skeletal muscle tissue. Skeletal muscle GLUT4 was trapped at perinuclear spaces, most pronounced in patients with CIM, but resided at the sarcolemma in control subjects. Glucose metabolism was not stimulated during euglycemic-hyperinsulinergic clamp. Insulin signal transduction was competent up to p-Akt activation; however, p-adenosine monophosphate-activated protein kinase (p-AMPK) was not detectable in CIM muscle. Electrical muscle stimulation increased p-AMPK, repositioned GLUT4, locally improved glucose metabolism, and prevented type-2 fiber atrophy. CONCLUSIONS: Insufficient GLUT4 translocation results in decreased glucose supply in patients with CIM. Failed AMPK activation is involved. Evoked muscle contraction may prevent muscle-specific AMPK failure, restore GLUT4 disposition, and diminish protein breakdown. Clinical trial registered with http://www.controlled-trials.com (registration number ISRCTN77569430).

Activating autoantibodies to the angiotensin II type I receptor play an important role in mediating hypertension in response to adoptive transfer of CD4+ T lymphocytes from placental ischemic rats.

Hypertension in rats with chronic placental ischemia (reduced uterine perfusion pressure, RUPP) is associated with elevated inflammatory cytokines, agonistic autoantibodies to the angiotensin II type I receptor (AT1-AA) and CD4(+) T cells; all of which are elevated in preclamptic women. Additionally, we have shown that adoptive transfer of RUPP CD4(+) T cells increases blood pressure, inflammatory cytokines, and sFlt-1. The objective of this study was to determine the long-term effects of RUPP CD4(+) T cells on AT1-AA, renal and systemic hemodynamics in pregnant rats. To answer this question CD4(+) T splenocytes were magnetically isolated on day 19 of gestation from control RUPP and normal pregnant (NP) rats and injected into a new group of NP rats at day 13 of gestation. On day 19 of gestation mean arterial pressure (MAP) and renal function (glomerular filtration rates, GFR) were analyzed and serum collected for AT1-AA analysis. To determine a role for AT1-AA to mediate RUPP CD4(+) T cell-induced blood pressure increases, MAP was analyzed in a second group of rats treated with AT1 receptor blockade losartan (10 mg·kg(-1)·day(-1)) and in a third group of rats treated with rituximab, a B cell-depleting agent (250 mg/kg) we have shown previously to decrease AT1-AA production in RUPP rats. MAP increased from 101 ± 2 mmHg NP to 126 ± 2 mmHg in RUPP rats (P < 0.001) and to 123 ± 1 mmHg in NP rats injected with RUPP CD4(+) T cells (NP+RUPP CD4(+)T cells) (P < 0.001). Furthermore, GFR decreased from 2.2 ml/min (n = 7) in NP rats to 1.0 ml/min (n = 5) NP+RUPP CD4(+)T cell. Circulating AT1-AA increased from 0.22 ± 0.1 units in NP rats to 13 ± 0.7 (P < 0.001) units in NP+RUPP CD4(+)T cell-treated rats but decreased to 8.34 ± 1 beats/min in NP+RUPP CD4(+) T cells chronically treated with rituximab. Hypertension in NP+RUPP CD4(+)T cell group was attenuated by losartan (102 ± 4 mmHg) and with B cell depletion (101 ± 5 mmHg). Therefore, we conclude that one mechanism of hypertension in response to CD4(+) T lymphocytes activated during placental ischemia is via AT1 receptor activation, potentially via AT1-AA during pregnancy.

C-Reactive Protein (CRP) Blocks the Desensitization of Agonistic Stimulated G Protein Coupled Receptors (GPCRs) in Neonatal Rat Cardiomyocytes.

Recently, C-reactive protein (CRP) was shown to affect intracellular calcium signaling and blood pressure in vitro and in vivo, respectively. The aim of the present study was to further investigate if a direct effect on G-protein coupled receptor (GPCR) signaling by CRP can be observed by using CRP in combination with different GPCR agonists on spontaneously beating cultured neonatal rat cardiomyocytes. All used agonists (isoprenaline, clenbuterol, phenylephrine, angiotensin II and endothelin 1) affected the beat rate of cardiomyocytes significantly and after washing them out and re-stimulation the cells developed a pronounced desensitization of the corresponding receptors. CRP did not affect the basal beating-rate nor the initial increase/decrease in beat-rate triggered by different agonists. However, CRP co-incubated cells did not exhibit desensitization of the respective GPCRs after the stimulation with the different agonists. This lack of desensitization was independent of the GPCR type, but it was dependent on the CRP concentration. Therefore, CRP interferes with the desensitization of GPCRs and has to be considered as a novel regulator of adrenergic, angiotensin-1 and endothelin receptors.

Functional autoantibodies against G-protein coupled receptors in patients with persistent Long-COVID-19 symptoms.

Impairment of health after overcoming the acute phase of COVID-19 is being observed more and more frequently. Here different symptoms of neurological and/or cardiological origin have been reported. With symptoms, which are very similar to the ones reported but are not caused by SARS-CoV-2, the occurrence of functionally active autoantibodies (fAABs) targeting G-protein coupled receptors (GPCR-fAABs) has been discussed to be involved. We, therefore investigated, whether GPCR-fAABs are detectable in 31 patients suffering from different Long-COVID-19 symptoms after recovery from the acute phase of the disease. The spectrum of symptoms was mostly of neurological origin (29/31 patients), including post-COVID-19 fatigue, alopecia, attention deficit, tremor and others. Combined neurological and cardiovascular disorders were reported in 17 of the 31 patients. Two recovered COVID-19 patients were free of follow-up symptoms. All 31 former COVID-19 patients had between 2 and 7 different GPCR-fAABs that acted as receptor agonists. Some of those GPCR-fAABs activate their target receptors which cause a positive chronotropic effect in neonatal rat cardiomyocytes, the read-out in the test system for their detection (bioassay for GPCR-fAAB detection). Other GPCR-fAABs, in opposite, cause a negative chronotropic effect on those cells. The positive chronotropic GPCR-fAABs identified in the blood of Long-COVID patients targeted the ß2-adrenoceptor (ß2-fAAB), the α1-adrenoceptor (α1-fAAB), the angiotensin II AT1-receptor (AT1-fAAB), and the nociceptin-like opioid receptor (NOC-fAAB). The negative chronotropic GPCR-fAABs identified targeted the muscarinic M2-receptor (M2-fAAB), the MAS-receptor (MAS-fAAB), and the ETA-receptor (ETA-fAAB). It was analysed which of the extracellular receptor loops was targeted by the autoantibodies.

Beyond the sarcomere: CSRP3 mutations cause hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a frequent genetic cardiac disease and the most common cause of sudden cardiac death in young individuals. Most of the currently known HCM disease genes encode sarcomeric proteins. Previous studies have shown an association between CSRP3 missense mutations and either dilated cardiomyopathy (DCM) or HCM, but all these studies were unable to provide comprehensive genetic evidence for a causative role of CSRP3 mutations. We used linkage analysis and identified a CSRP3 missense mutation in a large German family affected by HCM. We confirmed CSRP3 as an HCM disease gene. Furthermore, CSRP3 missense mutations segregating with HCM were identified in four other families. We used a newly designed monoclonal antibody to show that muscle LIM protein (MLP), the protein encoded by CSRP3, is mainly a cytosolic component of cardiomyocytes and not tightly anchored to sarcomeric structures. Our functional data from both in vitro and in vivo analyses suggest that at least one of MLP's mutated forms seems to be destabilized in the heart of HCM patients harbouring a CSRP3 missense mutation. We also present evidence for mild skeletal muscle disease in affected persons. Our results support the view that HCM is not exclusively a sarcomeric disease and also suggest that impaired mechano-sensory stress signalling might be involved in the pathogenesis of HCM.

The aptamer BC 007 for treatment of dilated cardiomyopathy: evaluation in Doberman Pinschers of efficacy and outcomes.

AIMS: Aptamer BC 007, a 15-mer single-strand DNA oligonucleotide (5'-GGTTGGTGTGGTTGG-3'), was developed to neutralize functional autoantibodies that bind to the extracellular domains of G protein-coupled receptors (GPCR-AAB), leading to the modulation of receptor-mediated signalling cascades that induce pathophysiological states. Among the GPCR-AAB, there are those directed against the ß1-adrenergic receptor (ß1-AAB) that are highly present in patients with dilated cardiomyopathy (DCM) and are increasingly accepted as disease drivers. Using Doberman Pinschers (DP) with DCM, which possess similarities with human DCM among these ß1-AAB positivity for that the disease-driving role in DP DCM was demonstrated, the safety of BC 007, efficacy for neutralizing ß1-AAB, and the DP's outcome were investigated. METHODS AND RESULTS: Fourteen client-owned ß1-AAB-positive DP with electrocardiographically and echocardiographically indicated DCM were treated with BC 007. For controlling, two groups were created: 14 ß1-AAB-positive DP with DCM not treated with BC 007 (Control 1) and 14 DP with DCM closely matched to the BC 007-treated DP (Control 2), retrospectively selected from the institutional database of DP. After treatment, DP were monitored both echocardiographically, and for ß1-AAB, and survival curves were calculated. Based on clinical and laboratory examination, no adverse effects associated with BC 007 treatment were observed during the study. Forty-eight hours after treatment, the DP's blood was free of ß1-AAB, which led to a reduction or stabilization of left ventricular end-systolic volume (ESVI) during ß1-AAB free time in 10 of the treated DP. In one DP, where ß1-AAB returned after 3 months and ESVI worsened again, a second BC 007 treatment after 9 months again cleared the blood from ß1-AAB and improved the ESVI. Compared with the controls, DP treated with BC 007 showed a significantly longer survival time [572 days, interquartile range (IQR) 442-840 days] vs. Control group 1 (266 days, IQR 97-438 days; logrank: P = 0.009) and Control group 2 (229 days, IQR 174-319 days; logrank: P = 0.012). CONCLUSIONS: Treatment with BC 007 for ß1-AAB neutralization was safe, resulted in a long-lasting reduction of ß1-AAB combined with improved cardiac function and prolonged the survival of DP with DCM. Using a natural large animal model of DCM considered superior to small animal models of immunization-induced cardiomyopathy, combined with a study design comparable with clinical trials, we believe that our results provide the basis for optimism that treatment with BC 007 might also be effective in human patients with DCM.

A Three-Part, Randomised Study to Investigate the Safety, Tolerability, Pharmacokinetics and Mode of Action of BC 007, Neutraliser of Pathogenic Autoantibodies Against G-Protein Coupled Receptors in Healthy, Young and Elderly Subjects.

BACKGROUND AND OBJECTIVE: BC 007 is a substance with a novel and innovative mode of action for the first-time causal treatment of chronic heart failure, associated with the occurrence of autoantibodies against the ß1-adrenoceptor, and other diseases of mostly the heart and vascular system, being accompanied by the occurrence of functionally active agonistic autoantibodies against G-protein-coupled receptors (fGPCR-AAb). The proposed mechanism of action of BC 007 is the neutralisation of these pathogenic autoantibodies which stimulate the respective receptor. To evaluate the safety, tolerability, pharmacokinetics and mode of action of BC 007, single intravenous infusions of increasing concentration were given to healthy young males and healthy elderly autoantibody-negative and autoantibody-positive participants of both sexes. METHODS: This study was subdivided into three parts. Part A was a single-centre, randomised, double-blind, placebo-controlled safety and tolerability study including healthy young male autoantibody-negative Whites (N = 23) and Asians (N = 1), testing doses of 15, 50 and 150 mg BC 007 (Cohorts 1-3) and elderly male and female Whites (N = 8), testing a dose of 150 mg BC 007 (Cohort 4), randomly assigned in a 3:1 ratio to BC 007 or placebo. Open-label Part B included fGPCR-AAb-positive subjects (50 and 150 mg BC 007, Cohorts 1 and 2, respectively). Open-label Part C included fGPCR-AAb-positive subjects for testing doses of 300, 450, 750, 1350 mg and 1900 mg BC 007. Lower doses were either given as an infusion or divided into a bolus plus infusion up to a dose of 300 mg followed by a constant bolus of 150 mg up to a dose of 750 mg, while at doses of 1350 mg and 1900 mg it was a slow infusion with a constant infusion rate. Infusion times increased with increasing dose from 20 min (15, 50 or 150 mg) to 40 min (300, 450 or 750 mg), 75 min (1350 mg) and 105 min (1900 mg). RESULTS: The mean observed BC 007 area under the concentration-time curve (AUC0-24) increased with increasing dose in a dose proportional manner (slope estimate of 1.039). No serious adverse events were observed. Drug-related adverse events were predominantly the expected mild-to-moderate increase in bleeding time (aPTT), beginning with a dose of 50 mg, which paralleled the infusion and returned to normal shortly after infusion. fGPCR-AAb neutralisation efficiency increased with increasing dose and was achieved for all subjects in the last cohort. CONCLUSION: BC 007 is demonstrated to be safe and well tolerated. BC 007 neutralised fGPCR-AAb, showing a trend for a dose-response relationship in elderly healthy but fGPCR-AAb-positive subjects. CLINICALTRIALS. GOV REGISTRATION NUMBER: NCT02955420.

Immunoadsorption for Treatment of Patients with Suspected Alzheimer Dementia and Agonistic Autoantibodies against Alpha1a-Adrenoceptor-Rationale and Design of the IMAD Pilot Study.

BACKGROUND: agonistic autoantibodies (agAABs) against G protein-coupled receptors (GPCR) have been linked to cardiovascular disease. In dementia patients, GPCR-agAABs against the α1- and ß2-adrenoceptors (α1AR- and ß2AR) were found at a prevalence of 50%. Elimination of agAABs by immunoadsorption (IA) was successfully applied in cardiovascular disease. The IMAD trial (Efficacy of immunoadsorption for treatment of persons with Alzheimer dementia and agonistic autoantibodies against alpha1A-adrenoceptor) investigates whether the removal of α1AR-AABs by a 5-day IA procedure has a positive effect (improvement or non-deterioration) on changes of hemodynamic, cognitive, vascular and metabolic parameters in patients with suspected Alzheimer's clinical syndrome within a one-year follow-up period. METHODS: the IMAD trial is designed as an exploratory monocentric interventional trial corresponding to a proof-of-concept phase-IIa study. If cognition capacity of eligible patients scores 19-26 in the Mini Mental State Examination (MMSE), patients are tested for the presence of agAABs by an enzyme-linked immunosorbent assay (ELISA)-based method, followed by a bioassay-based confirmation test, further screening and treatment with IA and intravenous immunoglobulin G (IgG) replacement. We aim to include 15 patients with IA/IgG and to complete follow-up data from at least 12 patients. The primary outcome parameter of the study is uncorrected mean cerebral perfusion measured in mL/min/100 gr of brain tissue determined by magnetic resonance imaging with arterial spin labeling after 12 months. CONCLUSION: IMAD is an important pilot study that will analyze whether the removal of α1AR-agAABs by immunoadsorption in α1AR-agAAB-positive patients with suspected Alzheimer's clinical syndrome may slow the progression of dementia and/or may improve vascular functional parameters.

Dysferlin-deficient muscular dystrophy features amyloidosis.

OBJECTIVE: Dysferlin (DYSF) gene mutations cause limb girdle muscular dystrophy type 2B and Miyoshi's myopathy. The consequences of DYSF mutations on protein structure are poorly understood. METHODS: The gene encoding dysferlin was sequenced in patients with suspected dysferlin-deficient muscular dystrophy. Muscle biopsy specimens were analyzed by histochemistry, immunohistochemistry, and electron microscopy. Antibodies against N-terminal dysferlin-peptides were raised. RESULTS: We found three families with muscular dystrophy caused by homozygous or compound heterozygous DYSF mutations featuring sarcolemmal and interstitial amyloid deposits. These mutations were all located in the N-terminal region of the protein. Dysferlin was a constituent of the amyloid deposits. INTERPRETATION: Limb girdle muscular dystrophy type 2B is the first muscular dystrophy associated with amyloidosis. Molecular treatment strategies will necessarily have to consider the presence of amyloidogenesis.

Analytics of Functional Autoantibodies in Patients with Chagas Disease.

Autoantibodies directed against G-protein-coupled receptors (GPCR-AAB), an autoantibody type discovered in the 1970s, affect functionally their targets and are therefore called functional autoantibodies. GPCR-AAB are increasingly accepted as the origin or amplifier of various diseases. Here, we describe the present "gold standard" for measurement of GPCR-AAB in human blood. This bioassay monitors the chronotropic activity of GPCR-AAB by recording the spontaneous beating of cultured neonatal rat cardiomyocytes. The construction of this bioassay and its procedure and standardization for GPCR-AAB measurement are described in detail and also include the application of the bioassay for GPCR-AAB differentiation related to first the targeted receptors and IgG subclasses carrying the GPCR-AAB and second the extracellular receptor-binding site and specific epitopes targeted by the GPCR-AAB.

Determination of Agonistically Acting Autoantibodies to the Adrenergic Beta-1 Receptor by Cellular Bioassay.

Agonistically acting autoantibodies directed against the adrenergic beta-1 receptor (beta1-AABs) are a pathogenic factor in diseases of the heart and circulatory system such as dilated cardiomyopathy. Here we describe the detection of such functionally active beta1-AABs from serum samples using spontaneously beating neonatal rat cardiomyocytes, which express the fully functional adrenergic beta-1 receptor coupled with the signal transduction pathway that induces chronotropy. With serum samples added (containing beta1-AABs), an increased positive chronotropic effect is caused that can be blocked by the subsequent addition of specific beta-blockers (abolishing this chronotropic response). The return to the basal beat rate of the cells by the addition of a beta-blocker proves the adrenergic beta-1 receptor specificity of the serum sample.

Doberman pinschers present autoimmunity associated with functional autoantibodies: A model to study the autoimmune background of human dilated cardiomyopathy.

BACKGROUND: Autoimmunity associated with autoantibodies against the ß1-adrenergic receptor (ß1-AAB) is increasingly accepted as the driver of human dilated cardiomyopathy (DCM). Unfortunately, there is a lack of animal models to extend the knowledge about ß1-AAB autoimmunity in DCM and to develop appropriate treatment strategies. OBJECTIVES: To introduce an animal model, we investigated the ß1-AAB associated autoimmunity in Doberman Pinscher (DP) with dilated cardiomyopathy, which has similarities to human DCM. MATERIALS AND METHODS: Eighty-seven DP with cardiomyopathy in terms of pathological ECG and echocardiography (DoCM) and 31 dogs (at enrollment) without DoCM (controls) were analyzed for serum activity of ß1-AAB with a bioassay that records the chronotropic response of spontaneously beating cultured neonatal rat cardiomyocytes to the DP's IgG. To locate the receptor binding site of ß1-AAB and the autoantibody's sensitivity to inhibition, competing experiments with related blockers were performed with the bioassay. In controls that developed DoCM during follow-up, ß1-AAB were analyzed during progress. RESULTS: Fifty-nine (67.8%) DoCM dogs and 19 (61.3%) controls were ß1-AAB positive. Of the controls that developed DoCM, 8 were ß1-AAB positive (p = 0.044 vs. dogs remaining in the control group); their ß1-AAB activity increased with the cardiomyopathy progress (p<0.02). To supplement DoCM group with the 9 animals which developed cardiomyopathy in the follow up, a more pronounced ß1-AAB positivity became visible in the DoCM group (p = 0.066). Total and cardiac mortality were higher in ß1-AAB positive DP (p = 0.002; p = 0037). The dogs' ß1-AAB recognized a specific epitope on the second extracellular receptor and were sensitive to inhibition by drugs already successfully tested to inhibit the corresponding human autoantibody. CONCLUSIONS: Doberman Pinschers presented ß1-AAB associated autoimmunity, similar as in the pathogenesis of human DCM. Consequently, DP could compensate the lack of animal models for the investigation of ß1-AAB autoimmunity in human DCM.

Dysfunction of dysferlin-deficient hearts.

Mutations in the gene encoding dysferlin cause limb-girdle muscular dystrophy 2B (LGMD2B), a disorder that is believed to spare the heart. We observed dilated cardiomyopathy in two out of seven LGMD2B patients and cardiac abnormalities in three others. Cardiac biopsies showed that dysferlin was completely absent from the sarcolemma and appeared to be trapped within the cardiomyocytes. SJL/J mice (33-week-old) had diminished end-systolic pressure and reduced dP/dt; however, the hearts were histologically normal. Gene expression profiles of cardiac tissue were obtained and later confirmed by quantitative RT-PCR. Dysferlin-deficient and control mice had different gene expression patterns in terms of cardiomyocyte Z-disc and signal transduction proteins. CapZ, LIM-domain-binding protein 3 (LDB3, MLP), cypher (ZASP), desmin, and the cardiac ankyrin-repeated protein (CARP) were differentially expressed, compared to controls. Mechanical stress induced by the nonselective beta-adrenergic agonist isoproterenol (5 mg/kg body weight) given daily for 10 days resulted in reduced fractional shortening and increased cardiac fibrosis in SJL/J mice as compared to controls. Isoproterenol also caused metalloproteinase-2 upregulation in SJL/J mice. In A/J mice, the effect of isoproterenol injection was even more dramatic and lead to premature death as well as marked sarcolemmal injury as demonstrated by Evans blue dye penetration. Our data suggest that disturbances in dysferlin as well as Z-line proteins and transcription factors particularly under mechanical stress cause cardiomyopathy.

Difference between beta1-adrenoceptor autoantibodies of human and animal origin-Limitations detecting beta1-adrenoceptor autoantibodies using peptide based ELISA technology.

Cell-based analytics for the detection of the beta1-adrenoceptor autoantibody (beta1-AAB) are functional, yet difficult to handle, and should be replaced by easily applicable, routine lab methods. Endeavors to develop solid-phase-based assays such as ELISA to exploit epitope moieties for trapping autoantibodies are ongoing. These solid-phase-based assays, however, are often unreliable when used with human patient material, in contrast to animal derived autoantibodies. We therefore tested an immunogen peptide-based ELISA for the detection of beta1-AAB, and compared commercially available goat antibodies against the 2nd extracellular loop of human beta1-adrenoceptor (ADRB1-AB) to autoantibodies enriched from patient material. The functionality of these autoantibodies was tested in a cell based assay for comparison and their structural appearance was investigated using 2D gel electrophoresis. The ELISA showed a limit of detection for ADRB1-AB of about 1.5 nmol antibody/L when spiked in human control serum and only about 25 nmol/L when spiked in species identical (goat) matrix material. When applied to samples of human origin, the ELISA failed to identify the specific beta1-AABs. A low concentration of beta1-AAB, together with structural inconsistency of the patient originated samples as seen from the 2D Gel appearance, might contribute to the failure of the peptide based ELISA technology to detect human beta1-AABs.

Characterization of Aptamer BC 007 Substance and Product Using Circular Dichroism and Nuclear Magnetic Resonance Spectroscopy.

Possible unwanted folding of biopharmaceuticals during manufacturing and storage has resulted in analysis schemes compared to small molecules that include bioanalytical characterization besides chemical characterization. Whether bioanalytical characterization is required for nucleotide-based drugs, may be decided on a case-by-case basis. Nucleotide-based pharmaceuticals, if chemically synthesized, occupy an intermediate position between small-molecule drugs and biologics. Here, we tested whether a physicochemical characterization of a nucleotide-based drug substance, BC 007, was adequate, using circular dichroism (CD) spectroscopy. Nuclear magnetic resonance confirmed CD data in one experimental setup. BC 007 forms a quadruplex structure under specific external conditions, which was characterized for its stability and structural appearance also after denaturation using CD and nuclear magnetic resonance. The amount of the free energy (ΔG0) involved in quadruplex formation of BC 007 was estimated at +8.7 kJ/mol when dissolved in water and +1.4 kJ/mol in 154 mM NaCl, indicating structural instability under these conditions. However, dissolution of the substance in 5 mM of KCl reduced the ΔG0 to -5.6 kJ/mol due to the stabilizing effect of cations. These results show that positive ΔG0 of quadruplex structure formation in water and aqueous NaCl prevents BC 007 from preforming stable 3-dimensional structures, which could potentially affect drug function.

Performance and in-house validation of a bioassay for the determination of beta1-autoantibodies found in patients with cardiomyopathy.

BACKGROUND: Autoantibodies specific for the adrenergic beta1-receptor were identified to be an essential factor for the pathogenesis of dilated cardiomyopathy. For the detection of these autoantibodies, a bioassay was developed and has been used, measuring the positive chronotropic effect on spontaneously beating neonatal rat cardiomyocytes. In order to use this bioassay as an analytical tool to monitor the effectiveness of autoantibody neutralizing therapy in a regulated field, there is a need to assess its analytical performance and validate it according to current guidelines. METHODS: Using standard autoantibody samples, the increased beat rate compared to the basal rate [delta beats/min] was recorded when investigating guideline required assay performance parameters. RESULTS: The analytical specificity and sensitivity of the bioassay was demonstrated. The limit of detection and positivity cut-off level were determined to be 3.56 and 7.97 delta beats/min, respectively. The coefficient of variation (CV) of all tested single values (four technical replicates each) was ≤15.2%. The CV of precision within each measuring series did not exceed 20%. Furthermore, the sample stability under a variety of different storage conditions was assessed, as well as the robustness of the cardiomyocyte preparations, which were both given. CONCLUSION: This bioassay fulfilled guideline determined quality requirements and proved to be appropriate for its application in clinical trials.

Novel sequence variants in dysferlin-deficient muscular dystrophy leading to mRNA decay and possible C2-domain misfolding.

Mutations in the gene encoding dysferlin (DYSF) cause the allelic autosomal recessive disorders limb girdle muscular dystrophy 2B and Miyoshi myopathy. It encompasses 55 exons spanning 150 kb of genomic DNA. Dysferlin is involved in membrane repair in skeletal muscle. We identified three families with novel sequence variants in DYSF. All affected family members showed limb girdle weakness and had reduced or absent dysferlin protein on immunohistochemistry. All exons of DYSF were screened by genomic sequencing. Five novel variants in DYSF were found: two missense mutations (c.895G>A and c.4022T>C), one 5' donor splice-site variant (c.855+1delG), one nonsense mutation (c.1448C>A), and a variant in the 3'UTR of DYSF (c.*107T>A). All alterations were confirmed by restriction enzyme analysis and not found in 400 control alleles. Nonsense mediated RNA decay or changes in the three-dimensional protein structure resulting in intracellular dysferlin aggregates and finally the lack of dysferlin protein were identified as consequences of the novel DYSF variants.

Effect of sialyl Lewis X-glycoliposomes on the inhibition of E-selectin-mediated tumour cell adhesion in vitro.

The aim of this study was to evaluate the potential of different types of sialyl Lewis X-conjugated liposomes as competitive inhibitors for tumour cell adhesion to endothelial E-selectin. Sterically stabilised liposomes with the sLeX ligand at the terminal end of the polyethyleneglycol (PEG) chain, as well as vesicles that had the ligand embedded within the PEG-layer, were compared to ligand-bearing liposomes without sterical stabilisation. First, 14 different tumour cell lines were characterised for their expression of sialyl Lewis X and/or A. Tumour cell adhesion was characterised in three static assays in vitro using: (i) immobilised E-selectin, (ii) CHO cells, transfected to express E-selectin and (iii) human umbilical vein endothelial cells (HUVEC). Sterically stabilised liposomes with the ligand at the terminal end of the polyethylene chain were the most effective inhibitors in all three assays and inhibited the adhesion of HT29 colon- and Lewis lung (LL) carcinoma cells by about 60-80%. The binding was not affected by a PEG-coating of the liposomes. Sterical stabilisation, on the other hand, completely prevented macrophage uptake (J774 cell line) independently of the presence of the ligand, while plain liposomes were taken up in an amount of 5.4 nmol liposomal lipids/10(6) macrophages.