SARS-CoV-2-reactive T-cell receptors isolated from convalescent COVID-19 patients confer potent T-cell effector function

Both B cells and T cells are involved in an effective immune response to SARS-CoV-2, the disease-causing virus of COVID-19. While B cells—with the indispensable help of CD4⁺ T cells—are essential to generate neutralizing antibodies, T cells on their own have been recognized as another major player in effective anti-SARS-CoV-2 immunity. In this report, we provide insights into the characteristics of individual HLA-A*02:01- and HLA-A*24:02-restricted SARS-CoV-2-reactive TCRs, isolated from convalescent COVID-19 patients. We observed that SARS-CoV-2-reactive T-cell populations were clearly detectable in convalescent samples and that TCRs isolated from these T cell clones were highly functional upon ectopic re-expression. The SARS-CoV-2-reactive TCRs described in this report mediated potent TCR signaling in reporter assays with low nanomolar EC50 values. We further demonstrate that these SARS-CoV-2-reactive TCRs conferred powerful T-cell effector function to primary CD8⁺ T cells as evident by a robust anti-SARS-CoV-2 IFN-γ response and in vitro cytotoxicity. We also provide an example of a long-lasting anti-SARS-CoV-2 memory response by reisolation of one of the retrieved TCRs 5 months after initial sampling. Taken together, these findings contribute to a better understanding of anti-SARS-CoV-2 T-cell immunity and may contribute to paving the way toward immunotherapeutics approaches targeting SARS-CoV-2.     

New population-based exome data are questioning the pathogenicity of previously cardiomyopathy-associated genetic variants

Cardiomyopathies are a heterogeneous group of diseases with various etiologies. We focused on three genetically determined cardiomyopathies: hypertrophic (HCM), dilated (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC). Eighty-four genes have so far been associated with these cardiomyopathies, but the disease-causing effect of reported variants is often dubious. In order to identify possible false-positive variants, we investigated the prevalence of previously reported cardiomyopathy-associated variants in recently published exome data. We searched for reported missense and nonsense variants in the NHLBI-Go Exome Sequencing Project (ESP) containing exome data from 6500 individuals. In ESP, we identified 94 variants out of 687 (14%) variants previously associated with HCM, 58 out of 337 (17%) variants associated with DCM, and 38 variants out of 209 (18%) associated with ARVC. These findings correspond to a genotype prevalence of 1:4 for HCM, 1:6 for DCM, and 1:5 for ARVC. PolyPhen-2 predictions were conducted on all previously published cardiomyopathy-associated missense variants. We found significant overrepresentation of variants predicted as being benign among those present in ESP compared with the ones not present. In order to validate our findings, seven variants associated with cardiomyopathy were genotyped in a control population and this revealed frequencies comparable with the ones found in ESP. In conclusion, we identified genotype prevalences up to more than one thousand times higher than expected from the phenotype prevalences in the general population (HCM 1:500, DCM 1:2500, and ARVC 1:5000) and our data suggest that a high number of these variants are not monogenic causes of cardiomyopathy.     

Cyclic mechanical stimulation rescues achilles tendon from degeneration in a bioreactor system

Physiotherapy is one of the effective treatments for tendinopathy, whereby symptoms are relieved by changing the biomechanical environment of the pathological tendon. However, the underlying mechanism remains unclear. In this study, we first established a model of progressive tendinopathy‐like degeneration in the rabbit Achilles. Following ex vivo loading deprivation culture in a bioreactor system for 6 and 12 days, tendons exhibited progressive degenerative changes, abnormal collagen type III production, increased cell apoptosis, and weakened mechanical properties. When intervention was applied at day 7 for another 6 days by using cyclic tensile mechanical stimulation (6% strain, 0.25 Hz, 8 h/day) in a bioreactor, the pathological changes and mechanical properties were almost restored to levels seen in healthy tendon. Our results indicated that a proper biomechanical environment was able to rescue early‐stage pathological changes by increased collagen type I production, decreased collagen degradation and cell apoptosis. The ex vivo model developed in this study allows systematic study on the effect of mechanical stimulation on tendon biology. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1888–1896, 2015.     

Higher Glucocorticoid Secretion in the Physiological Range Is Associated With Lower Bone Strength at the Proximal Radius in Healthy Children: Importance of Protein Intake Adjustment

Whether higher production of glucocorticoids (GCs) within the physiological range may already be affecting bone status in healthy children is unknown. Because dietary protein intake affects both bone and GCs, we examined the association of urinary measures of glucocorticoid status and cortical bone in healthy non‐obese children, after particularly controlling for protein intake. Proximal forearm bone parameters were measured by peripheral quantitative computed tomography (pQCT). Subjects studied (n = 175, 87 males, aged 6 to 18 years) had two 24‐hour urine samples collected: the first sample at 1 year before bone measurement, and the second sample at the time of bone measurement. Major urinary GC metabolites were measured by mass spectrometry and summed to assess daily adrenal GC secretion (∑C21). Urinary free cortisol (UFF) and cortisone (UFE) were summed to assess potentially bioactive free GCs (UFF + UFE). After controlling for several covariates and especially urinary nitrogen (the biomarker of protein intake) cortisol secretion ∑C21 was inversely associated with all analyzed pQCT measures of bone quality. ∑C21 also predicted a higher endosteal and lower periosteal circumference, explaining both a smaller cortical area and (together with lower BMD) a lower strength‐strain‐index (SSI). UFF + UFE, UFE itself, and a urinary metabolite‐estimate of 11beta‐hydroxysteroid dehydrogenase type1 (11beta‐HSD1) activity showed corresponding reciprocal associations (p < 0.05) with BMD and bone mineral content, but not with SSI and bone geometry variables. In conclusion, higher GC levels, even within the physiological range, appear to exert negative influences on bone modeling and remodeling already during growth. Our physiological data also suggest a relevant role of cortisone as the direct source for intracrine‐generated cortisol by bone cell 11beta‐HSD1. © 2014 American Society for Bone and Mineral Research.