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Children infected with SARS-CoV-2 rarely progress to respiratory failure, but the risk of mortality in infected people over 85 years of age remains high, despite vaccination and improving treatment options. Here, we take a comprehensive, multidisciplinary approach to investigate differences in the cellular landscape and function of paediatric (70y) nasal epithelial cells experimentally infected with SARS-CoV-2. Our data reveal that nasal epithelial cell subtypes show different tropism to SARS-CoV-2, correlating with age, ACE2 and TMPRSS2 expression. Ciliated cells are a viral replication centre across all age groups, but a distinct goblet inflammatory subtype emerges in infected paediatric cultures, identifiable by high expression of interferon stimulated genes and truncated viral genomes. In contrast, infected elderly cultures show a proportional increase in ITGB6hiprogenitors, which facilitate viral spread and are associated with dysfunctional epithelial repair pathways.Graphical Abstract

T1 Figure 1ConclusionsOverall, this largest paediatric single cell COVID-19 study to date showed significant differences in response to SARS-CoV-2 between children and adults, reflecting the changes of the immune landscape over developmental time, which in children are dominated by naive and innate responses.

While a substantial proportion of adults infected with SARS-CoV-2 progress to develop severe disease, children rarely manifest respiratory complications. Therefore, understanding differences in the local and systemic response to SARS-CoV-2 infection between children and adults may provide important clues about the pathogenesis of SARS-CoV-2 infection. To address this, we first generated a healthy reference multi-omics single cell data set from children (n=30) in whom we have profiled triple matched samples: nasal and tracheal brushings and PBMCs, where we track the developmental changes for 42 airway and 31 blood cell populations from infancy, through childhood to adolescence. This has revealed the presence of naive B and T lymphocytes in neonates and infants with a unique gene expression signature bearing hallmarks of innate immunity. We then contrast the healthy reference with equivalent data from severe paediatric and adult COVID-19 patients (total n=27), from the same three types of samples: upper and lower airways and blood. We found striking differences: children with COVID-19 as opposed to adults had a higher proportion of innate lymphoid and non-clonally expanded naive T cells in peripheral blood, and a limited interferon-response signature. In the airway epithelium, we found the highest viral load in goblet and ciliated cells and describe a novel inflammatory epithelial cell population. These cells represent a transitional regenerative state between secretory and ciliated cells; they were found in healthy children and were enriched in paediatric and adult COVID-19 patients. Epithelial cells display an antiviral and neutrophil-recruiting gene signature that is weaker in severe paediatricversusadult COVID-19. Our matched blood and airway samples allowed us to study the spatial dynamics of infection. Lastly, we provide a user-friendly interface for this data1as a highly granular reference for the study of immune responses in airways and blood in children.

The COVID-19 pandemic, caused by SARS coronavirus 2 (SARS-CoV-2), has resulted in excess morbidity and mortality as well as economic decline. To characterise the systemic host immune response to SARS-CoV-2, we performed single-cell RNA-sequencing coupled with analysis of cell surface proteins, providing molecular profiling of over 800,000 peripheral blood mononuclear cells from a cohort of 130 patients with COVID-19. Our cohort, from three UK centres, spans the spectrum of clinical presentations and disease severities ranging from asymptomatic to critical. Three control groups were included: healthy volunteers, patients suffering from a non-COVID-19 severe respiratory illness and healthy individuals administered with intravenous lipopolysaccharide to model an acute inflammatory response. Full single cell transcriptomes coupled with quantification of 188 cell surface proteins, and T and B lymphocyte antigen receptor repertoires have provided several insights into COVID-19: 1. a new non-classical monocyte state that sequesters platelets and replenishes the alveolar macrophage pool; 2. platelet activation accompanied by early priming towards megakaryopoiesis in immature haematopoietic stem/progenitor cells and expansion of megakaryocyte-primed progenitors; 3. increased clonally expanded CD8+ effector:effector memory T cells, and proliferating CD4+ and CD8+ T cells in patients with more severe disease; and 4. relative increase of IgA plasmablasts in asymptomatic stages that switches to expansion of IgG plasmablasts and plasma cells, accompanied with higher incidence of BCR sharing, as disease severity increases. All data and analysis results are available for interrogation and data mining through an intuitive web portal. Together, these data detail the cellular processes present in peripheral blood during an acute immune response to COVID-19, and serve as a template for multi-omic single cell data integration across multiple centers to rapidly build powerful resources to help combat diseases such as COVID-19.

We present the case of an 88-year-old gentleman who presented to hospital septic with bilateral leg cellulitis, pulmonary oedema and hypotension. He had no history of heart disease but had had bilateral carpal tunnel releases. His condition deteriorated with refractory hypotension in spite of fluid filling, inotropic and vasopressor support. His echocardiogram showed an infiltrative cardiomyopathy with a speckled myocardium, severe concentric left and right ventricular increased wall thickness, diastolic dysfunction, biatrial dilatation and restrictive physiology in keeping with cardiac amyloidosis. He developed atrial fibrillation and worsening respiratory failure due to fluid overload and was intubated and ventilated but continued to decline and passed away. The degree of heart failure in the absence of ischaemia, the patient’s advanced age, echocardiographic findings and past history of carpal tunnel syndrome in a male are strongly indicative of a diagnosis of wild-type cardiac transthyretin amyloidosis. We discuss the key features and intensive care management of this disease.

Misfolding, polymerization, and defective secretion of functional alpha-1 antitrypsin underlies the predisposition to severe liver and lung disease in alpha-1 antitrypsin deficiency. We have identified a novel (Ala336Pro, Baghdad) deficiency variant and characterized it relative to the wild-type (M) and Glu342Lys (Z) alleles. The index case is a homozygous individual of consanguineous parentage, with levels of circulating alpha-1 antitrypsin in the moderate deficiency range, but is a biochemical phenotype that could not be classified by standard methods. The majority of the protein was present as functionally inactive polymer, and the remaining monomer was 37% active relative to the wild-type protein. These factors combined indicate an 85 to 95% functional deficiency, similar to that seen with ZZ homozygotes. Biochemical, biophysical, and computational studies further defined the molecular basis of this deficiency. These studies demonstrated that native Ala336Pro alpha-1 antitrypsin could populate the polymerogenic intermediate—and therefore polymerize—more readily than either wild-type alpha-1 antitrypsin or the Z variant. In contrast, folding was far less impaired in Ala336Pro alpha-1 antitrypsin than in the Z variant. The data are consistent with a disparate contribution by the “breach” region and “shutter” region of strand 5A to folding and polymerization mechanisms. Moreover, the findings demonstrate that, in these variants, folding efficiency does not correlate directly with the tendency to polymerize in vitro or in vivo. They therefore differentiate generalized misfolding from polymerization tendencies in missense variants of alpha-1 antitrypsin. Clinically, they further support the need to quantify loss-of-function in alpha-1 antitrypsin deficiency to individualize patient care.

Introduction A1ATD is an autosomal co-dominant condition where homozygosity for the Z-allele results, classically, in emphysematous lung involvement, and liver fibrosis dependant on polymerisation rate of aberrant protein. 1 The FIB4 score non-invasively estimates risk of liver fibrosis, 2 but has not previously been investigated in A1ATD. We completed preliminary assessment of the utility of FIB4 in our A1ATD cohort. Whilst the standard of care in A1ATD should be joint respiratory-hepatology services, not all patients are able to access this. A simple tool to guide referral to hepatology services could therefore be clinically useful to the respiratory community. Methods We report data from 30 PiZZ patients with ultrasound (USS) characterisation of liver disease. An abnormal USS was considered as any abnormality other than cysts, thus including features of cirrhosis and fatty infiltration. FIB4 was calculated as [Age (years)xAST(U/l)]/[Platelets (10 9 )xALT(U/l)]. The most recent lung physiology was recorded as FEV1 (%predicted), diffusion coefficient (KCO,%predicted) and residual volume (RV,%predicted). Body mass index (BMI) was calculated. Results The 30 patients had a mean age of 54 ± 12.4 years, 14 were male. Lung function showed mean FEV1 1.85 ± 1.12 L (61.3 ± 30.9%), KCO 1.05 ± 0.40 mmol/min/kPa/L (66.4 ± 22.2%) and RV 3.58 ± 1.36 L (171.8 ± 50.4%). The mean FIB4 was 1.76 ± 1.36. Eight (26.7%) patients had liver disease on USS. FIB4 cut-off values of 1.45 and 3.25 were utilised, as they are widely validated. 3 Of patients >3.25, 100% had abnormal scans (PPV 100%), and of patients Conclusions The FIB4 score, calculated from routine laboratory variables and age, may be useful to rule in and out significant liver involvement in A1ATD with reasonable sensitivity and specificity. Further work is required for validation against biopsy, the gold-standard assessment. We confirm a previously noted lack of association between liver disease and emphysema severity, 4 and highlight the association between higher BMI and higher fibrosis risk in A1ATD.

A 27-year-old woman was referred from her general practitioner (GP) 6 weeks postpartum with weight loss, dyspnoea and bilateral leg swelling. She had been treated by the GP for a chest infection the week before. On admission she was tachycardic, hypotensive and hypoxic with bilateral leg oedema and bibasal crackles. A chest radiograph showed diffuse multinodular opacification. A CT pulmonary angiogram showed dilated pulmonary artery. Echocardiogram confirmed right ventricular strain and dilation. Sputum microscopy was positive for acid-fast bacilli. The patient developed confusion and low-grade fever and the CT head scan showed meningeal involvement. One year of antituberculous therapy was started and she made a clinical recovery after 10 days and was discharged with regular follow-up. An echocardiogram showed resolution of the right heart strain 4 months later.

In this cluster randomised controlled trial, Cartwright et al 1 evaluated the outcomes of telehealth on patient reported outcomes in a primary care population with chronic disease. Telehealth is the use of remote data exchange between patients at home and health professionals to assist management of long-term conditions. It is heralded as a solution to our growing elderly population with its significant chronic disease burden. The Department of Health has commissioned …