Background Increased understanding of whether individuals who have recovered from COVID-19 are protected from future SARS-CoV-2 infection is an urgent requirement. We aimed to investigate whether antibodies against SARS-CoV-2 were associated with a decreased risk of symptomatic and asymptomatic reinfection. Methods A large, multicentre, prospective cohort study was done, with participants recruited from publicly funded hospitals in all regions of England. All health-care workers, support staff, and administrative staff working at hospitals who could remain engaged in follow-up for 12 months were eligible to join The SARS-CoV-2 Immunity and Reinfection Evaluation study. Participants were excluded if they had no PCR tests after enrolment, enrolled after Dec 31, 2020, or had insufficient PCR and antibody data for cohort assignment. Participants attended regular SARS-CoV-2 PCR and antibody testing (every 2–4 weeks) and completed questionnaires every 2 weeks on symptoms and exposures. At enrolment, participants were assigned to either the positive cohort (antibody positive, or previous positive PCR or antibody test) or negative cohort (antibody negative, no previous positive PCR or antibody test). The primary outcome was a reinfection in the positive cohort or a primary infection in the negative cohort, determined by PCR tests. Potential reinfections were clinically reviewed and classified according to case definitions (confirmed, probable, or possible) and symptom-status, depending on the hierarchy of evidence. Primary infections in the negative cohort were defined as a first positive PCR test and seroconversions were excluded when not associated with a positive PCR test. A proportional hazards frailty model using a Poisson distribution was used to estimate incidence rate ratios (IRR) to compare infection rates in the two cohorts. Findings From June 18, 2020, to Dec 31, 2020, 30 625 participants were enrolled into the study. 51 participants withdrew from the study, 4913 were excluded, and 25 661 participants (with linked data on antibody and PCR testing) were included in the analysis. Data were extracted from all sources on Feb 5, 2021, and include data up to and including Jan 11, 2021. 155 infections were detected in the baseline positive cohort of 8278 participants, collectively contributing 2 047 113 person-days of follow-up. This compares with 1704 new PCR positive infections in the negative cohort of 17 383 participants, contributing 2 971 436 person-days of follow-up. The incidence density was 7·6 reinfections per 100 000 person-days in the positive cohort, compared with 57·3 primary infections per 100 000 person-days in the negative cohort, between June, 2020, and January, 2021. The adjusted IRR was 0·159 for all reinfections (95% CI 0·13–0·19) compared with PCR-confirmed primary infections. The median interval between primary infection and reinfection was more than 200 days. Interpretation A previous histo...

Background BNT162b2 mRNA and ChAdOx1 nCOV-19 adenoviral vector vaccines have been rapidly rolled out in the UK from December, 2020. We aimed to determine the factors associated with vaccine coverage for both vaccines and documented the vaccine effectiveness of the BNT162b2 mRNA vaccine in a cohort of health-care workers undergoing regular asymptomatic testing. MethodsThe SIREN study is a prospective cohort study among staff (aged ≥18 years) working in publicly-funded hospitals in the UK. Participants were assigned into either the positive cohort (antibody positive or history of infection [indicated by previous positivity of antibody or PCR tests]) or the negative cohort (antibody negative with no previous positive test) at the beginning of the follow-up period. Baseline risk factors were collected at enrolment, symptom status was collected every 2 weeks, and vaccination status was collected through linkage to the National Immunisations Management System and questionnaires. Participants had fortnightly asymptomatic SARS-CoV-2 PCR testing and monthly antibody testing, and all tests (including symptomatic testing) outside SIREN were captured. Data cutoff for this analysis was Feb 5, 2021. The follow-up period was Dec 7, 2020, to Feb 5, 2021. The primary outcomes were vaccinated participants (binary ever vacinated variable; indicated by at least one vaccine dose recorded by at least one of the two vaccination data sources) for the vaccine coverage analysis and SARS-CoV-2 infection confirmed by a PCR test for the vaccine effectiveness analysis. We did a mixed-effect logistic regression analysis to identify factors associated with vaccine coverage. We used a piecewise exponential hazard mixed-effects model (shared frailty-type model) using a Poisson distribution to calculate hazard ratios to compare time-to-infection in unvaccinated and vaccinated participants and estimate the impact of the BNT162b2 vaccine on all PCR-positive infections (asymptomatic and symptomatic). This study is registered with ISRCTN, number ISRCTN11041050, and is ongoing.Findings 23 324 participants from 104 sites (all in England) met the inclusion criteria for this analysis and were enrolled. Included participants had a median age of 46•1 years (IQR 36•0-54•1) and 19 692 (84%) were female; 8203 (35%) were assigned to the positive cohort at the start of the analysis period, and 15 121 (65%) assigned to the negative cohort. Total follow-up time was 2 calendar months and 1 106 905 person-days (396 318 vaccinated and 710 587 unvaccinated). Vaccine coverage was 89% on Feb 5, 2021, 94% of whom had BNT162b2 vaccine. Significantly lower coverage was associated with previous infection, gender, age, ethnicity, job role, and Index of Multiple Deprivation score. During follow-up, there were 977 new infections in the unvaccinated cohort, an incidence density of 14 infections per 10 000 person-days; the vaccinated cohort had 71 new infections 21 days or more after their first dose (incidence density of eight infections per 10 000 person-days) and nine infecti...

In airway and renal epithelia, the glucocorticoid-mediated stimulation of amiloride-sensitive Na ؉ transport is associated with increased expression of the epithelial Na ؉ channel ␣ subunit (␣ENaC). In H441 lung cells, 100 nM dexamethasone increases amiloride-sensitive shortcircuit current (3.3 A/cm 2 to 7.5 A/cm 2 ), correlating with a 5-fold increase in ␣ENaC mRNA expression that could be blocked by actinomycin D. To explore transcriptional regulation of ␣ENaC, the human ␣ENaC 5-flanking region was cloned and tested in H441 cells. By deletion analysis, a ϳ150-base pair region 5 to the upstream promoter was identified that, when stimulated with 100 nM dexamethasone, increased luciferase expression 15-fold. This region, which contains two imperfect GREs, also functioned when coupled to a heterologous promoter. When individually tested, only the downstream GRE functioned in cis and bound GR in a gel mobility shift assay. In the M-1 collecting duct line Na ؉ transport, m␣ENaC expression and luciferase expression from ␣ENaC genomic fragments were also increased by 100 nM dexamethasone. In a colonic cell line, HT29, trans-activation via a heterologously expressed glucocorticoid receptor restored glucocorticoid-stimulated ␣ENaC gene transcription. We conclude that glucocorticoids stimulate ␣ENaC expression in kidney and lung via activation of a hormone response element in the 5-flanking region of h␣ENaC and this response, in part, is the likely basis for the up-regulation of Na ؉ transport in these sites.

H441 cells, a bronchiolar epithelial cell line, develop a glucocorticoid-regulated amiloride-sensitive Na(+) transport pathway on permeable supports (R. Sayegh, S. D. Auerbach, X. Li, R. Loftus, R. Husted, J. B. Stokes, and C. P. Thomas. J Biol Chem 274: 12431-12437, 1999). To understand its molecular basis, we examined the effect of glucocorticoids (GC) on epithelial Na(+) channel (ENaC)-alpha, -beta, and -gamma and sgk1 expression and determined the biophysical properties of Na(+) channels in these cells. GC stimulated the expression of ENac-alpha, -beta, and -gamma and sgk1 mRNA, with the first effect seen by 1 h. These effects were abolished by actinomycin D, but not by cycloheximide, indicating a direct stimulatory effect on ENaC and sgk1 mRNA synthesis. The GC effect on transcription of ENaC-alpha mRNA was accompanied by a significant increase in ENaC-alpha protein levels. GC also stimulated ENaC-alpha, -beta, and -gamma and sgk1 mRNA expression in A549 cells, an alveolar type II cell line. To determine the biophysical properties of the Na(+) channel, single-channel currents were recorded from cell-attached H441 membranes. An Na(+)-selective channel with slow kinetics and a slope conductance of 10.8 pS was noted, properties similar to ENaC-alpha, -beta, and -gamma expressed in Xenopus laevis oocytes. These experiments indicate that amiloride-sensitive Na(+) transport is mediated through classic ENaC channels in human lung epithelia and that GC-regulated Na(+) transport is accompanied by increased transcription of each of the component subunits and sgk1.

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sFlt1-e15a emerged as an alternate transcript of Flt1 late in evolution with the insertion of an AluSq sequence into the primate genome after the emergence of the simian infraorder about 40 million years ago. sFlt1-e15a is particularly abundant in human placenta and trophoblasts and is also highly expressed in nonhuman primate placenta. The expressed protein has a C-terminal polyserine tail and, like reference sequence sFlt1 (sFlt1-i13), is glycosylated and secreted. Consistent with a role in placental pathophysiology, hypoxia stimulates sFlt1-e15a expression in isolated cytotrophoblasts and a trophoblast cell line, and differentiation into syncytiotrophoblasts further enhances the effect of hypoxia. Placental levels of sFlt1-e15a and sFlt1-i13 transcripts are significantly elevated in patients with preeclampsia compared with normal pregnancies. We speculate that sFlt1-e15a may contribute to the pathophysiology of preeclampsia.

In lung and collecting duct epithelia, glucocorticoid (GC)-stimulated Na+ transport is preceded by an increase in the protein kinase sgk1, which in turn regulates the activity of the epithelial Na+ channel (ENaC). We investigated the mechanism for GC-regulated human sgk1 expression in lung and renal epithelia. sgk1 mRNA was increased in these epithelia by GCs, and this was inhibited by actinomycin D and superinduced by cycloheximide, consistent with a transcriptional effect that did not require protein synthesis. To understand the basis for transcriptional regulation, the transcription initiation site was mapped and the 5'-flanking region cloned by PCR. A 3-kb fragment of the upstream region was coupled to luciferase and transfected into A549 cells. By deletion analysis, an imperfect GC response element (GRE) was identified that was necessary and sufficient for GC responsiveness. When tested with cell extracts, a specific protein recognized by an anti-GC receptor (GR) antibody bound the GRE in gel mobility shift assays. We conclude that GCs stimulate sgk1 expression in human epithelial cells via activation of a GRE in the 5'-flanking region of sgk1.

Atypical hemolytic uremic syndrome (aHUS) is a thrombotic microangiopathy caused by uncontrolled activation of the alternative pathway of complement at the cell surface level that leads to microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney failure. In approximately one half of affected patients, pathogenic loss-of-function variants in regulators of complement or gain-of-function variants in effectors of complement are identified, clearly implicating complement in aHUS. However, there are strong lines of evidence supporting the presence of additional genetic contributions to this disease. To identify novel aHUS-associated genes, we completed a comprehensive screen of the complement and coagulation pathways in 36 patients with sporadic aHUS using targeted genomic enrichment and massively parallel sequencing. After variant calling, quality control, and hard filtering, we identified 84 reported or novel nonsynonymous variants, 22 of which have been previously associated with disease. Using computational prediction methods, 20 of the remaining 62 variants were predicted to be deleterious. Consistent with published data, nearly one half of these 42 variants (19; 45%) were found in genes implicated in the pathogenesis of aHUS. Several genes in the coagulation pathway were also identified as important in the pathogenesis of aHUS. PLG, in particular, carried more pathogenic variants than any other coagulation gene, including three known plasminogen deficiency mutations and a predicted pathogenic variant. These data suggest that mutation screening in patients with aHUS should be broadened to include genes in the coagulation pathway.