Objectives: Use of corticosteroids is common in the treatment of coronavirus disease 2019, but clinical effectiveness is controversial. We aimed to investigate the association of corticosteroids therapy with clinical outcomes of hospitalized COVID-19 patients. Methods: In this single-centre, retrospective cohort study, adult patients with confirmed coronavirus disease 2019 and dead or discharged between 29 December 2019 and 15 February 2020 were studied; 1:1 propensity score matchings were performed between patients with or without corticosteroid treatment. A multivariable COX proportional hazards model was used to estimate the association between corticosteroid treatment and in-hospital mortality by taking corticosteroids as a time-varying covariate. Results: Among 646 patients, the in-hospital death rate was higher in 158 patients with corticosteroid administration (72/158, 45.6% vs. 56/488, 11.5%, p < 0.0001). After propensity score matching analysis, no significant differences were observed in in-hospital death between patients with and without corticosteroid treatment (47/124, 37.9% vs. 47/124, 37.9%, p 1.000). When patients received corticosteroids before they required nasal high-flow oxygen therapy or mechanical ventilation, the in-hospital death rate was lower than that in patients who were not administered corticosteroids (17/86, 19.8% vs. 26/86, 30.2%, log rank p 0.0102), whereas the time from admission to clinical improvement was longer (13 (IQR 10-17) days vs. 10 (IQR 8-13) days; p < 0.001). Using the Cox proportional hazards regression model accounting for time varying exposures in matched pairs, corticosteroid therapy was not associated with mortality difference (HR 0.98, 95% CI 0.93-1.03, p 0.4694). Discussion: Corticosteroids use in COVID-19 patients may not be associated with in-hospital mortality. (C) 2020 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

The possible effects of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) on COVID-19 disease severity have generated considerable debate. We performed a single-center, retrospective analysis of hospitalized adult COVID-19 patients in Wuhan, China, who had definite clinical outcome (dead or discharged) by February 15, 2020. Patients on anti-hypertensive treatment with or without ACEI/ARB were compared on their clinical characteristics and outcomes. The medical records from 702 patients were screened. Among the 101 patients with a history of hypertension and taking at least one anti-hypertensive medication, 40 patients were receiving ACEI/ARB as part of their regimen, and 61 patients were on antihypertensive medication other than ACEI/ARB. We observed no statistically significant differences in percentages of in-hospital mortality (28% vs. 34%, P = 0.46), ICU admission (20% vs. 28%, P = 0.37) or invasive mechanical ventilation (18% vs. 26%, P = 0.31) between patients with or without ACEI/ARB treatment. Further multivariable adjustment of age and gender did not provide evidence for a significant association between ACEI/ARB treatment and severe COVID-19 outcomes. Our findings confirm the lack of an association between chronic receipt of renin-angiotensin system antagonists and severe outcomes of COVID-19. Patients should continue previous anti-hypertensive therapy until further evidence is available.

Influenza virus infection poses a heavy burden on global health and economics. With the advancement in viral pathogen detection methods, the role of virus infection in community-acquired pneumonia has been increasingly recognized. The disease spectrum of influenza ranges from asymptomatic infection to severe or even fatal illness. Progress has been made in recent years to identify risk factors including lymphopenia and hypoxia for influenza mortality. Immunopathology plays an important role in influenza pathogenesis. The disturbed homeostasis after virus infection consists of both an excessive inflammatory phase and an immune suppression phase, collectively described as viral sepsis. Multiple antiviral therapies have been tested and some were advanced to late-phase clinical trials, including polymerase inhibitors, hemagglutinin inhibitors, host-acting antivirals, monoclonal antibodies, and adjunctive immunomodulatory therapies. Combination therapies have been shown to increase antiviral efficacy and genetic resistance barrier. In this review, we summarized the recent advances in our understanding of the disease pathogenesis, as well as the progress in antiviral therapy development. We also pointed out current key knowledge gaps in influenza research. Hopefully, experience gained from seasonal influenza research will prepare us for the next influenza pandemic and emerging respiratory pathogens.

Protozoan parasites of the phylum Apicomplexa actively move through tissue to initiate and perpetuate infection. The regulation of parasite motility relies on cyclic nucleotide-dependent kinases, but how these kinases are activated remains unknown. Here, using an array of biochemical and cell biology approaches, we show that the apicomplexan parasite Toxoplasma gondii expresses a large guanylate cyclase (TgGC) protein, which contains several upstream ATPase transporter-like domains. We show that TgGC has a dynamic localization, being concentrated at the apical tip in extracellular parasites, which then relocates to a more cytosolic distribution during intracellular replication. Conditional TgGC knockdown revealed that this protein is essential for acute-stage tachyzoite growth, as TgGC-deficient parasites were defective in motility, host cell attachment, invasion, and subsequent host cell egress. We show that TgGC is critical for a rapid rise in cytosolic [Ca2+] and for secretion of microneme organelles upon stimulation with a cGMP agonist, but these deficiencies can be bypassed by direct activation of signaling by a Ca2+ ionophore. Furthermore, we found that TgGC is required for transducing changes in extracellular pH and [K+] to activate cytosolic [Ca2+] flux. Together, the results of our work implicate TgGC as a putative signal transducer that activates Ca2+ signaling and motility in Toxoplasma.

The phylum Apicomplexa comprises a group of obligate intracellular parasites that alternate between intracellular replicating stages and actively motile extracellular forms that move through tissue. Parasite cytosolic Ca2+ signalling activates motility, but how this is switched off after invasion is complete to allow for replication to begin is not understood. Here, we show that the cyclic adenosine monophosphate (cAMP)-dependent protein kinase A catalytic subunit 1 (PKAc1) of Toxoplasma is responsible for suppression of Ca2+ signalling upon host cell invasion. We demonstrate that PKAc1 is sequestered to the parasite periphery by dual acylation of PKA regulatory subunit 1 (PKAr1). Upon genetic depletion of PKAc1 we show that newly invaded parasites exit host cells shortly thereafter, in a perforin-like protein 1 (PLP-1)-dependent fashion. Furthermore, we demonstrate that loss of PKAc1 prevents rapid down-regulation of cytosolic [Ca2+] levels shortly after invasion. We also provide evidence that loss of PKAc1 sensitises parasites to cyclic GMP (cGMP)-induced Ca2+ signalling, thus demonstrating a functional link between cAMP and these other signalling modalities. Together, this work provides a new paradigm in understanding how Toxoplasma and related apicomplexan parasites regulate infectivity.