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 ( f AABs) targeting G-protein coupled receptors (GPCR- f AABs) has been discussed to be involved. We, therefore investigated, whether GPCR- f AABs 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- f AABs that acted as receptor agonists. Some of those GPCR- f AABs 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- f AAB detection). Other GPCR- f AABs, in opposite, cause a negative chronotropic effect on those cells. The positive chronotropic GPCR- f AABs identified in the blood of Long-COVID patients targeted the β 2 -adrenoceptor (β 2 - f AAB), the α 1 -adrenoceptor (α 1 - f AAB), the angiotensin II AT1-receptor (AT1- f AAB), and the nociceptin—like opioid receptor (NOC- f AAB). The negative chronotropic GPCR- f AABs identified targeted the muscarinic M 2 -receptor (M 2 - f AAB), the MAS-receptor (MAS- f AAB), and the ETA-receptor (ETA- f AAB). It was analysed which of the extracellular receptor loops was targeted by the autoantibodies.
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 β1-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 (f GPCR-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 f GPCR-AAbpositive subjects (50 and 150 mg BC 007, Cohorts 1 and 2, respectively). Open-label Part C included f GPCR-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 (AUC 0-24) 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. f GPCR-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 f GPCR-AAb, showing a trend for a dose-response relationship in elderly healthy but f GPCR-AAb-positive subjects. ClinicalTrials.gov Registration Number NCT02955420.
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.
BackgroundAutoantibodies 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.MethodsUsing standard autoantibody samples, the increased beat rate compared to the basal rate [delta beats/min] was recorded when investigating guideline required assay performance parameters.ResultsThe 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.ConclusionThis bioassay fulfilled guideline determined quality requirements and proved to be appropriate for its application in clinical trials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.