Next-Generation Sequencing of T and B Cell Receptor Repertoires from COVID-19 Patients Showed Signatures Associated with Severity of Disease.

We profiled adaptive immunity in COVID-19 patients with active infection or after recovery and created a repository of currently >14 million B and T cell receptor (BCR and TCR) sequences from the blood of these patients. The B cell response showed converging IGHV3-driven BCR clusters closely associated with SARS-CoV-2 antibodies. Clonality and skewing of TCR repertoires were associated with interferon type I and III responses, early CD4+ and CD8+ T cell activation, and counterregulation by the co-receptors BTLA, Tim-3, PD-1, TIGIT, and CD73. Tfh, Th17-like, and nonconventional (but not classical antiviral) Th1 cell polarizations were induced. SARS-CoV-2-specific T cell responses were driven by TCR clusters shared between patients with a characteristic trajectory of clonotypes and traceability over the disease course. Our data provide fundamental insight into adaptive immunity to SARS-CoV-2 with the actively updated repository providing a resource for the scientific community urgently needed to inform therapeutic concepts and vaccine development.

Senescence-induced inflammation: an important player and key therapeutic target in atherosclerosis.

Inflammation is a hallmark and potent driver of pathological vascular remodelling in atherosclerosis. However, current anti-inflammatory therapeutic strategies have shown mixed results. As an alternative perspective on the conundrum of chronic inflammation emerging evidence points towards a small subset of senescent cells as a critical player and central node driving atherosclerosis. Senescent cells belonging to various cell types are a dominant and chronic source of a large array of pro-inflammatory cytokines and various additional plaque destabilizing factors, being involved with various aspects of atherosclerosis pathogenesis. Antagonizing these key agitators of local chronic inflammation and plaque instability may provide a causative and multi-purpose therapeutic strategy to treat atherosclerosis. Anti-senescence treatment options with translational potential are currently in development. However, several questions and challenges remain to be addressed before these novel treatment approaches may enter the clinical setting.

Imaging of chemokine receptor CXCR4 expression in culprit and nonculprit coronary atherosclerotic plaque using motion-corrected [68Ga]pentixafor PET/CT.

PURPOSE: The chemokine receptor CXCR4 is a promising target for molecular imaging of CXCR4+ cell types, e.g. inflammatory cells, in cardiovascular diseases. We speculated that a specific CXCR4 ligand, [68Ga]pentixafor, along with novel techniques for motion correction, would facilitate the in vivo characterization of CXCR4 expression in small culprit and nonculprit coronary atherosclerotic lesions after acute myocardial infarction by motion-corrected targeted PET/CT. METHODS: CXCR4 expression was analysed ex vivo in separately obtained arterial wall specimens. [68Ga]Pentixafor PET/CT was performed in 37 patients after stent-based reperfusion for a first acute ST-segment elevation myocardial infarction. List-mode PET data were reconstructed to five different datasets using cardiac and/or respiratory gating. Guided by CT for localization, the PET signals of culprit and various groups of nonculprit coronary lesions were analysed and compared. RESULTS: Ex vivo, CXCR4 was upregulated in atherosclerotic lesions, and mainly colocalized with CD68+ inflammatory cells. In vivo, elevated CXCR4 expression was detected in culprit and nonculprit lesions, and the strongest CXCR4 PET signal (median SUVmax 1.96; interquartile range, IQR, 1.55-2.31) was observed in culprit coronary artery lesions. Stented nonculprit lesions (median SUVmax 1.45, IQR 1.23-1.88; P = 0.048) and hot spots in naive remote coronary segments (median SUVmax 1.34, IQR 1.23-1.74; P = 0.0005) showed significantly lower levels of CXCR4 expression. Dual cardiac/respiratory gating provided the strongest CXCR4 PET signal and the highest lesion detectability. CONCLUSION: We demonstrated the basic feasibility of motion-corrected targeted PET/CT imaging of CXCR4 expression in coronary artery lesions, which was triggered by vessel wall inflammation but also by stent-induced injury. This novel methodology may serve as a platform for future diagnostic and therapeutic clinical studies targeting the biology of coronary atherosclerotic plaque.

Regulator of G-Protein Signaling 5 Prevents Smooth Muscle Cell Proliferation and Attenuates Neointima Formation.

OBJECTIVE: Regulator of G-protein signaling 5 (RGS5) is abundantly expressed in vascular smooth muscle cells (SMCs) and inhibits G-protein signaling by enhancing the guanosine triphosphate-hydrolyzing activity of Gα-subunits. In the present study, we investigated the effects of RGS5 on vascular SMC function in vitro and neointima formation after wire-induced injury in mice and determined the underlying mechanisms. APPROACH AND RESULTS: We found a robust expression of RGS5 in native arteries of C57BL/6 mice and a highly significant downregulation within neointimal lesions 10 and 21 days after vascular injury as assessed by quantitative polymerase chain reaction, immunoblotting, and immunohistochemistry. In vitro, RGS5 was found significantly downregulated after mitogenic stimulation of human coronary artery SMCs. To restore RGS5 levels, SMCs were transduced with adenoviral vectors encoding wild-type RGS5 or a nondegradable mutant. RGS5-WT and, even more prominently, the C2A-RGS5 mutant prevented SMC proliferation and migration. In contrast, the siRNA-mediated knockdown of RGS5 significantly augmented SMC proliferation. Following overexpression of RGS5, fluorescence-activated cell sorting analysis of propidium iodide-stained cells indicated cell cycle arrest in G0/G1 phase. Mechanistically, inhibition of the phosphorylation of the extracellular signal-regulated kinase 1/2 and mitogen-activated protein kinase downstream signaling was shown to be responsible for the anti-proliferative effect of RGS5. Following wire-induced injury of the femoral artery in C57BL/6 mice, adenoviral-mediated overexpression of RGS5-WT or C2A-RGS5 significantly reduced SMC proliferation and neointima formation in vivo. CONCLUSIONS: Downregulation of RGS5 is an important prerequisite for SMC proliferation in vitro and in vivo. Therefore, reconstitution of RGS5 levels represents a promising therapeutic option to prevent vascular remodeling processes.

Intermittent Fasting After ST-Segment-Elevation Myocardial Infarction Improves Left Ventricular Function: The Randomized Controlled INTERFAST-MI Trial.

BACKGROUND: Intermittent fasting has shown positive effects on numerous cardiovascular risk factors. The INTERFAST-MI trial (Intermittent Fasting in Myocardial Infarction) has been designed to study the effects of intermittent fasting on cardiac function after STEM (ST-segment-elevation myocardial infarction) and the feasibility of future multicenter trials. METHODS: The INTERFAST-MI study was a prospective, randomized, controlled, nonblinded, single-center investigator-initiated trial. From October 1, 2020, to July 15, 2022, 48 patients were randomized to the study groups intermittent fasting or regular diet and followed for 6 months with follow-up visits at 4 weeks and 3 months. RESULTS: In all, 22 of 24 patients in the intermittent fasting group with a mean age of 58.54±12.29 years and 20 of 24 patients in the regular diet group with a mean age of 59.60±13.11 years were included in the intention-to-treat population. The primary efficacy end point (improvement in left ventricular ejection fraction after 4 weeks) was significantly greater in the intermittent fasting group compared with the control group (mean±SD, 6.636±7.122%. versus 1.450±4.828%; P=0.038). This effect was still significant and even more pronounced after 3 and 6 months. The patients in the intermittent fasting group showed a greater reduction in diastolic blood pressure and body weight compared with the control group. The mean adherence of patients in the intermittent fasting group was a median of 83.7% (interquartile range, 69.0%-98.4%) of all days. None of the patients from either group reported dizziness, syncope, or collapse. CONCLUSIONS: Our results suggest that intermittent fasting after myocardial infarction may be safe and could improve left ventricular function after STEMI. REGISTRATION: URL: https://www.drks.de; Unique identifier: DRKS00021784.

Opposing effects of ATP and adenosine on barrier function of rat coronary microvasculature.

ATP can differentially affect the micro- and macrovascular endothelial barrier. It has been shown that it can both increase and/or decrease macromolecule permeability of microvascular endothelial cells and microvessels, in vivo. We hypothesised that the barrier stabilising effect is mediated by ATP itself via P2 receptors, while barrier-disrupting effect is mediated by its metabolite adenosine via adenosine receptors. The effects of ATP, ADP, AMP and adenosine on barrier function were studied in cultured rat coronary microvascular endothelial monolayers (RCEC) in vitro, as well as in rat mesentery vessels, and in rat hearts in vivo. ATP and ADP showed a biphasic effect on permeability of RCEC monolayers with a reduction followed by a later increase in albumin permeability. The permeability decreasing effect of ATP was enhanced by ecto-nucleotidase inhibitor ARL67156 while permeability increasing effect was enhanced by apyrase, an extracellular ecto-nucleotidase. Moreover, the permeability increasing effect was abrogated by adenosine receptor antagonists, 8-phenyltheophylline (8-PT) and DMPX. Adenosine and adenosine receptor agonists 5'-(N-ethylcarboxamido)-adenosine (NECA), CGS21680, and R-PIA enhanced albumin permeability which was antagonised by 8-PT, A(1), and A(2) but not by A(3) receptor antagonists. Likewise, immunofluorescence microscopy of VE-cadherin and actin showed that NECA induces a disturbance of intercellular junctions. Pre-incubation of ATP antagonised the effects of NECA on permeability, actin cytoskeleton and intercellular junctions. Similar effects of the applied substances were observed in rat mesentery artery by determining the vascular leakage using intravital microscopy as well as in rat hearts by assessing myocardial water contents in vivo. In conclusion, the study demonstrates that in RCEC, ATP, ADP, and its metabolite adenosine play opposing roles on endothelial barrier function.

Inhibition of STAT3 signaling prevents vascular smooth muscle cell proliferation and neointima formation.

Dedifferentiation, migration, and proliferation of resident vascular smooth muscle cells (SMCs) are key components of neointima formation after vascular injury. Activation of signal transducer and activator of transcription-3 (STAT3) is suggested to be critically involved in this process, but the complex regulation of STAT3-dependent genes and the functional significance of inhibiting this pathway during the development of vascular proliferative diseases remain elusive. In this study, we demonstrate that STAT3 was activated in neointimal lesions following wire-induced injury in mice. Phosphorylation of STAT3 induced trans-activation of cyclin D1 and survivin in SMCs in vitro and in neointimal cells in vivo, thus promoting proliferation and migration of SMCs as well as reducing apoptotic cell death. WP1066, a highly potent inhibitor of STAT3 signaling, abrogated phosphorylation of STAT3 and dose-dependently inhibited the functional effects of activated STAT3 in stimulated SMCs. The local application of WP1066 via a thermosensitive pluronic F-127 gel around the dilated arteries significantly inhibited proliferation of neointimal cells and decreased the neointimal lesion size at 3 weeks after injury. Even though WP1066 application attenuated the injury-induced up-regulation of the chemokine RANTES at 6 h after injury, there was no significant effect on the accumulation of circulating cells at 1 week after injury. In conclusion, these data identify STAT3 as a key molecule for the proliferative response of SMC and neointima formation. Moreover, inhibition of STAT3 by the potent and specific compound WP1066 might represent a novel and attractive approach for the local treatment of vascular proliferative diseases.

Effect of intermittent fasting after ST-elevation myocardial infarction on left ventricular function: study protocol of a pilot randomised controlled trial (INTERFAST-MI).

INTRODUCTION: Preclinical studies consistently show robust disease-modifying effects of intermittent fasting in animal models of cardiovascular disease. However, the impact of intermittent fasting on cardiovascular endpoints after myocardial infarction has not been investigated in a clinical trial so far. METHODS AND ANALYSIS: The INTERmittent FASTing after Myocardial Infarction (INTERFAST-MI) trial is a monocentric prospective randomised controlled non-confirmatory pilot study including 48 patients with ST-segment elevation myocardial infarction. They will be randomised in a 1:1 ratio to either intermittent fasting (daily time-restricted eating; consuming food for not more than 8 hours/day, fasting for at least 16 hours/day) or to a control group without a particular diet. The follow-up time is 6 months. The prespecified primary outcome is change in left ventricular systolic function at 4 weeks from baseline to estimate effect size required to establishing sample size and power calculation for a future full-scale trial. Secondary outcomes include protocol adherence, recruitment, major adverse cardiac events, revascularisation, changes in left ventricular systolic function at 3 and 6 months, patient weight, blood pressure, and serum markers of inflammation and cardiovascular disease. Enrolment began on 1 November 2020 and is expected to conclude in December 2021. ETHICS AND DISSEMINATION: The trial has received ethics approval from the Medical Ethics Committee of the Martin-Luther-University Halle-Wittenberg. Results of the study will be submitted for publication in a peer-reviewed journal and presented at scientific conferences. TRIAL REGISTRATION NUMBER: DRKS00021784.

Empagliflozin prevents neointima formation by impairing smooth muscle cell proliferation and accelerating endothelial regeneration.

Background: Empagliflozin, an inhibitor of the sodium glucose co-transporter 2 (SGLT2) and developed as an anti-diabetic agent exerts additional beneficial effects on heart failure outcomes. However, the effect of empagliflozin on vascular cell function and vascular remodeling processes remains largely elusive. Methods/Results: Immunocytochemistry and immunoblotting revealed SGLT2 to be expressed in human smooth muscle (SMC) and endothelial cells (EC) as well as in murine femoral arteries. In vitro, empagliflozin reduced serum-induced proliferation and migration of human diabetic and non-diabetic SMCs in a dose-dependent manner. In contrast, empagliflozin significantly increased the cell count and migration capacity of human diabetic ECs, but not of human non-diabetic ECs. In vivo, application of empagliflozin resulted in a reduced number of proliferating neointimal cells in response to femoral artery wire-injury in C57BL/6J mice and prevented neointima formation. Comparable effects were observed in a streptozocin-induced diabetic model of apolipoprotein E-/- mice. Conclusive to the in vitro-results, re-endothelialization was not significantly affected in C57BL/6 mice, but improved in diabetic mice after treatment with empagliflozin assessed by Evan's Blue staining 3 days after electric denudation of the carotid artery. Ribonucleic acid (RNA) sequencing (RNA-seq) of human SMCs identified the vasoactive peptide apelin to be decisively regulated in response to empagliflozin treatment. Recombinant apelin mimicked the in vitro-effects of empagliflozin in ECs and SMCs. Conclusion: Empagliflozin significantly reduces serum-induced proliferation and migration of SMCs in vitro and prevents neointima formation in vivo, while augmenting EC proliferation in vitro and re-endothelialization in vivo after vascular injury. These data document the functional impact of empagliflozin on vascular human SMCs and ECs and vascular remodeling in mice for the first time.

Circulating smooth muscle progenitor cells in arterial remodeling.

The proliferation and migration of vascular smooth muscle cells (SMCs) from the media toward the intimal layer are key components in vascular proliferative diseases. In addition, the differentiation of circulating bone marrow-derived mononuclear cells (BMMCs) into SMCs has been described to contribute to lesion progression in experimental models of atherosclerosis, transplant arteriosclerosis, and neointima formation. In vitro, CD14(+) BMMCs from peripheral blood acquire a spindle-shaped phenotype and express specific SMC markers in response to platelet-derived growth factor-BB. However, the 'trans-differentiation' capacity of BMMCs into definitive SMCs in vivo remains a highly controversial issue. Whereas SMCs within atherosclerotic plaques have been demonstrated to be exclusively of local origin, more severe injury models have shown a wide diversity of SMCs or smooth muscle-like cells derived from BMMCs. In hindsight, these discrepancies may be attributed to methodological differences, e.g., the use of high-resolution microscopy or the specificity of the SMC marker proteins. In fact, the analysis of mouse strains that express marker genes under the control of a highly specific smooth muscle-myosin heavy chain (SM-MHC) promoter and a time-course analysis on the dynamic process of neointima formation have recently shown that BMMCs temporarily express α-smooth muscle actin, not SM-MHC. Additionally, BM-derived cells disappear from the neointimal lesion after the inflammatory response to the injury has subsided. Although CD14(+)/CD68(+) have important paracrine effects on arterial lesion progression, BMMCs account for more of the 'SMC-like macrophages' than the highly 'trans-differentiated' and definitive SMCs in vivo. This article is part of a special issue entitled, "Cardiovascular Stem Cells Revisited".

3-Deazaadenosine prevents smooth muscle cell proliferation and neointima formation by interfering with Ras signaling.

3-Deazaadenosine (c3Ado) is a potent inhibitor of S-adenosylhomocysteine hydrolase, which regulates cellular methyltransferase activity. In the present study, we sought to determine the effect of c3Ado on vascular smooth muscle cell (VSMC) function and neointima formation in vivo. c3Ado dose-dependently prevented the proliferation and migration of human coronary VSMCs in vitro. This was accompanied by an increased expression of the cyclin-dependent kinase inhibitors p21(WAF1/Cip1), p27(Kip1), a decreased expression of G(1)/S phase cyclins, and a lack of retinoblastoma protein hyperphosphorylation. In accordance with these findings, fluorescence-activated cell-sorting analysis of propidium iodide-stained cells indicated a cell cycle arrest in the G(0)/G(1) phase. Importantly, c3Ado did not affect the number of viable (trypan blue exclusion) or apoptotic cells (TUNEL). Mechanistically, c3Ado prevented FCS-induced Ras carboxyl methylation and membrane translocation and activity by inhibiting isoprenylcysteine carboxyl methyltransferase and reduced FCS-induced extracellular signal-regulated kinase (ERK)1/2 and Akt phosphorylation in a dose-dependent manner. Conversely, rescuing signal transduction by overexpression of a constitutive active Ras mutant abrogated c3Ado's effect on proliferation. For in vivo studies, the femoral artery of C57BL/6 mice was dilated and mice were fed a diet containing 150 microg of c3Ado per day. c3Ado prevented dilation-induced Ras activation, as well as ERK1/2 and Akt phosphorylation in vivo. At day 21, VSMC proliferation (proliferating-cell nuclear antigen [PCNA]-positive cells), as well as the neointima/media ratio (0.7+/-0.2 versus 1.6+/-0.4; P<0.05) were significantly reduced, without any changes in the number of apoptotic cells. Our data indicate that c3Ado interferes with Ras methylation and function and thereby with mitogenic activation of ERK1/2 and Akt, preventing VSMC cell cycle entry and proliferation and neointima formation in vivo. Thus, therapeutic inhibition of S-adenosylhomocysteine hydrolase by c3Ado may represent a save and effective novel approach to prevent vascular proliferative disease.

Time-course analysis on the differentiation of bone marrow-derived progenitor cells into smooth muscle cells during neointima formation.

OBJECTIVE: Bone marrow-derived progenitor cells have been implicated to contribute to neointima formation, but the time course and extent of their accumulation and differentiation into vascular cells and, most importantly, the long-term contribution of bone marrow-derived progenitor cells to the vascular lesion remain undefined. METHODS AND RESULTS: Wire-induced injury of the femoral artery was performed on chimeric C57BL/6 mice transplanted with bone marrow from transgenic mice expressing enhanced green fluorescence protein, and vessels were harvested at 3 days, 1, 2, 3, 4, 6, and 16 weeks after dilatation (n=8 animals per time point). Using high-resolution microscopy, we unexpectedly found that the expression of smooth muscle cell or endothelial cell markers in enhanced green fluorescence protein positive cells was a very rare event. Indeed, most of the enhanced green fluorescence protein positive cells that accumulated during the acute inflammatory response were identified as monocytes/macrophages, and their number declined at later time points. In contrast, a substantial fraction of highly proliferative stem cell antigen-1 and CD34(+) but enhanced green fluorescence protein negative and thus locally derived cells were detected in the adventitia. CONCLUSIONS: These data provide evidence that the differentiation of bone marrow-derived progenitor cells into smooth muscle cell or endothelial cell lineages seems to be an exceedingly rare event. Moreover, the contribution of bone marrow-derived cells to the cellular compartment of the neointima is limited to a transient period of the inflammatory response.

Toxic Epidermal Necrolysis Caused by Allopurinol: A Serious but Still Underestimated Adverse Reaction.

BACKGROUND Allopurinol is the first-line therapy for the treatment of symptomatic hyperuricemia (gout). In clinical practice, there is a tendency to overmedicate asymptomatic patients who have elevated serum urate. Because of this practice, serious and life-threatening reactions such as Stevens-Johnson syndrome (SJS) or the more dramatic toxic epidermal necrolysis (TEN), both frequently caused by uricostatics, may occur. To increase awareness of these complications, we present a case with fulminant TEN caused by allopurinol. CASE REPORT A 75-year-old woman noticed a mildly itching skin rash accompanied by fever, shivering, and weakness approximately 3 weeks after taking newly prescribed allopurinol. The initial clinical examination revealed a generalized maculopapular exanthema. An adverse drug reaction was recognized, and allopurinol was discontinued. Ambulatory supportive therapy using prednisolone and cetirizine was started but failed. The patient developed a progressive exanthema with painful widespread blistering, skin peeling, and mucosal and conjunctival lesions. After recurrent presentations to the Emergency Department, the patient was transferred to our Intensive Care Unit (ICU). The clinical picture confirmed the suspected diagnosis of TEN. Massive fluid replacement, prednisolone, and cyclosporine were used as anti-inflammatory therapy. Polyhexanide and octenidine were applied for local treatment. All treatment measures were guided daily by a multidisciplinary team. After 7 days in the ICU, the patient was transferred to the Dermatology Department and was discharged from the hospital 42 days later. CONCLUSIONS With the prescription of allopurinol, there should be awareness of potentially life-threatening complications such as SJS or TEN. Patients with SJS or TEN should be immediately transferred to an ICU with dermatological expertise and multidisciplinary therapy.

SARS-CoV-2-specific antibody rearrangements in prepandemic immune repertoires of risk cohorts and patients with COVID-19.

A considerable fraction of B cells recognize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with germline-encoded elements of their B cell receptor, resulting in the production of neutralizing and nonneutralizing antibodies. We found that antibody sequences from different discovery cohorts shared biochemical properties and could be retrieved across validation cohorts, confirming the stereotyped character of this naive response in coronavirus disease 2019 (COVID-19). While neutralizing antibody sequences were found independently of disease severity, in line with serological data, individual nonneutralizing antibody sequences were associated with fatal clinical courses, suggesting detrimental effects of these antibodies. We mined 200 immune repertoires from healthy individuals and 500 repertoires from patients with blood or solid cancers - all acquired prior to the pandemic - for SARS-CoV-2 antibody sequences. While the largely unmutated B cell rearrangements occurred in a substantial fraction of immune repertoires from young and healthy individuals, these sequences were less likely to be found in individuals over 60 years of age and in those with cancer. This reflects B cell repertoire restriction in aging and cancer, and may to a certain extent explain the different clinical courses of COVID-19 observed in these risk groups. Future studies will have to address if this stereotyped B cell response to SARS-CoV-2 emerging from unmutated antibody rearrangements will create long-lived memory.

BET bromodomain-containing epigenetic reader proteins regulate vascular smooth muscle cell proliferation and neointima formation.

AIMS: Recent studies revealed that the bromodomain and extra-terminal (BET) epigenetic reader proteins resemble key regulators in the underlying pathophysiology of cancer, diabetes, or cardiovascular disease. However, whether they also regulate vascular remodelling processes by direct effects on vascular cells is unknown. In this study, we investigated the effects of the BET proteins on human smooth muscle cell (SMC) function in vitro and neointima formation in response to vascular injury in vivo. METHODS AND RESULTS: Selective inhibition of BETs by the small molecule (+)-JQ1 dose-dependently reduced proliferation and migration of SMCs without apoptotic or toxic effects. Flow cytometric analysis revealed a cell cycle arrest in the G0/G1 phase in the presence of (+)-JQ1. Microarray- and pathway analyses revealed a substantial transcriptional regulation of gene sets controlled by the Forkhead box O (FOXO1)1-transcription factor. Silencing of the most significantly regulated FOXO1-dependent gene, CDKN1A, abolished the antiproliferative effects. Immunohistochemical colocalization, co-immunoprecipitation, and promoter-binding ELISA assay data confirmed that the BET protein BRD4 directly binds to FOXO1 and regulates FOXO1 transactivational capacity. In vivo, local application of (+)-JQ1 significantly attenuated SMC proliferation and neointimal lesion formation following wire-induced injury of the femoral artery in C57BL/6 mice. CONCLUSION: Inhibition of the BET-containing protein BRD4 after vascular injury by (+)-JQ1 restores FOXO1 transactivational activity, subsequent CDKN1A expression, cell cycle arrest and thus prevents SMC proliferation in vitro and neointima formation in vivo. Inhibition of BET epigenetic reader proteins might thus represent a promising therapeutic strategy to prevent adverse vascular remodelling.

Landscape of T-cell repertoires with public COVID-19-associated T-cell receptors in pre-pandemic risk cohorts.

OBJECTIVES: T cells have an essential role in the antiviral defence. Public T-cell receptor (TCR) clonotypes are expanded in a substantial proportion of COVID-19 patients. We set out to exploit their potential use as read-out for COVID-19 T-cell immune responses. METHODS: We searched for COVID-19-associated T-cell clones with public TCRs, as defined by identical complementarity-determining region 3 (CDR3) beta chain amino acid sequence that can be reproducibly detected in the blood of COVID-19 patients. Of the different clonotype identification algorithms used in this study, deep sequencing of brain tissue of five patients with fatal COVID-19 delivered 68 TCR clonotypes with superior representation across 140 immune repertoires of unrelated COVID-19 patients. RESULTS: Mining of immune repertoires from subjects not previously exposed to the virus showed that these clonotypes can be found in almost 20% of pre-pandemic immune repertoires of healthy subjects, with lower representation in repertoires from risk groups like individuals above the age of 60 years or patients with cancer. CONCLUSION: Together, our data show that at least a proportion of the SARS-CoV-2 T-cell response is mediated by public TCRs that are present in repertoires of unexposed individuals. The lower representation of these clones in repertoires of risk groups or failure to expand such clones may contribute to more unfavorable clinical COVID-19 courses.

Inhibition of matrix deposition: a new strategy for prevention of restenosis after balloon angioplasty.

Restenosis after balloon angioplasty or stent placement is characterized by local accumulation of mainly vascular smooth muscle cells and the synthesis of extracellular matrix molecules (ECM).We hypothesized that inhibition of ECM synthesis represents a strategy to prevent trauma-induced neointima formation. Rats were treated with pirfenidone (1 g/kg of body weight orally.), an inhibitor of growth factor-induced collagen synthesis, and subjected to balloon denudation of the carotid artery. Two weeks later, computer-aided morphometry was done and compared with untreated controls (each n = 6). Neointimal proliferative activity was quantified immunohistochemically by counting PCNA-positive nuclei, and collagen deposition was visualized by picrosirius red staining and semi-quantified by Northern blot. Control-injured animals developed marked neointimal thickening within 2 weeks (I/M, mean intima to media ratio: 2.42 +/- 0.15) resulting in an 89.2% luminal narrowing. The neointima mainly consisted of vascular smooth muscle cells embedded in collagen. Neointima formation was strongly reduced when balloon-injured animals had been treated with pirfenidone (I/M ratio 0.22 +/- 0.08, P < 0.001), resulting in a minimal residual narrowing of the lumen (7.9%). I/M ratio did not further increase even after discontinuation of the drug for 14 days (0.35 +/- 0.13). Proliferative activity within the neointima was unaffected by the drug, 4.4% versus 4.8% of neointimal cells stained positive for PCNA in carotid arteries of treated versus untreated animals, respectively. However, picrosirius red staining demonstrated marked attenuation of collagen deposition, a finding that was further confirmed by Northern blot of homogenized vessels. Pirfenidone, currently being investigated clinically for the treatment of various fibrotic diseases, is able to prevent neointimal lesion formation most likely through inhibition of local ECM deposition. Targeting matrix deposition may have an intriguing potential for the prevention of vascular proliferative diseases.

Early Escalation of Mechanical Circulatory Support Stabilizes and Potentially Rescues Patients in Refractory Cardiogenic Shock.

BACKGROUND: Limited progress has been made in the management of cardiogenic shock (CS). Morbidity and mortality of refractory CS remain high. The effects of mechanical circulatory support (MCS) are promising, although many aspects are elusive. We evaluated efficacy and safety of early combined MCS (Impella microaxial pump + venoarterial extracorporeal membrane oxygenation [VA-ECMO]) in refractory CS and aimed to determine factors for decision-making in combined MCS. METHODS AND RESULTS: We analyzed 69 consecutive patients with refractory CS from our registry requiring combined MCS. In 12 cases, therapy was actively withdrawn according to patient's will. Patients were severely sick (Survival After Venoarterial ECMO score mean±SD, -8.9±4.4) predicting 30% in-hospital survival; ventilation 94%, dialysis 56%. Impella pumps and VA-ECMO were combined early (duration of combined MCS: median 94 hours; interquartile range, 49-150 hours). Early MCS escalation stabilized patients rapidly, reducing number and doses of catecholamines (P<0.05 versus baseline) while hemodynamics improved. Reflecting an improved microcirculation, lactate levels normalized within 24 hours (P<0.05 versus baseline). Despite refractory CS and disease severity, survival was favorable (on MCS 61%, 30 days 49%, 6 months 40%). In multivariate Cox-regression, duration of shock-to-first device (hours, hazard ratio, 1.05 [95% CI, 1.01-1.08]; P=0.007) and lactate levels after 12 hours of MCS (hazard ratio, 1.28 [95% CI, 1.09-1.51]; P=0.002) independently predicted survival. Additional right ventricular failure predisposed to futility (hazard ratio, 8.48 [95% CI, 1.85-38.91]; P=0.006). CONCLUSIONS: The early and consequent combination of MCS by Impella microaxial pumps and VA-ECMO enables stabilization and may rescue high-risk patients with refractory CS at low overall risk. Independent predictors of survival may guide prognostication, decision-making, and allocation of medical resources.

Calpain counteracts mechanosensitive apoptosis of vascular smooth muscle cells in vitro and in vivo.

Mechanical forces contribute to vascular remodeling processes. Elevated mechanical stress causes apoptosis of vascular smooth muscle cells (VSMCs) within the media. This study examined the role of the cystein protease calpain in force-induced vascular cell apoptosis and its effect on injury-induced vascular remodeling processes. VSMCs were exposed to cyclic tensile force in vitro, which resulted in increased p53 protein expression and transcriptional activity as well as a significant increase of apoptotic VSMCs. Apoptosis was prevented by the p53 inhibitor pifithrin and by p53 antisense oligonucleotides, indicating dependency of force-induced apoptosis on p53. Simultaneously, calpain activity increased by mechanical stress. Prevention of calpain activation by calpeptin or antisense oligonucleotides augmented strain-induced p53 expression and transcriptional activity, resulting in a further increase of apoptotic rate. p53 protein was directly disintegrated by activated calpain. The in vivo relevance of the findings was tested: pharmacologic inhibition of initial calpain activation augmented early apoptosis of medial VSMCs 24 h after balloon injury in a p53-dependent manner but resulted in a marked increase in late neointima formation. We conclude that calpain counteracts mechanically induced excessive VSMC apoptosis through its p53-degrading properties, which identifies calpain as a key regulator of mechanosensitive remodeling processes of the vascular wall.