Human macrophages differentiated in the presence of vitamin D3 restrict dengue virus infection and innate responses by downregulating mannose receptor expression

ABSTARCT: Severe dengue disease is associated with high viral loads and overproduction of pro-inflammatory cytokines, suggesting impairment in the control of dengue virus (DENV) and the mechanisms that regulate cytokine production. Vitamin D3 has been described as an important modulator of immune responses to several pathogens. Interestingly, increasing evidence has associated vitamin D with decreased DENV infection and early disease recovery, yet the molecular mechanisms whereby vitamin D reduces DENV infection are not well understood. METHODS AND PRINCIPAL FINDINGS: Macrophages represent important cell targets for DENV replication and consequently, they are key drivers of dengue disease. In this study we evaluated the effect of vitamin D3 on the differentiation of monocyte-derived macrophages (MDM) and their susceptibility and cytokine response to DENV. Our data demonstrate that MDM differentiated in the presence of vitamin D3 (D3-MDM) restrict DENV infection and moderate the classical inflammatory cytokine response. Mechanistically, vitamin D3-driven differentiation led to reduced surface expression of C-type lectins including the mannose receptor (MR, CD206) that is known to act as primary receptor for DENV attachment on macrophages and to trigger of immune signaling. Consequently, DENV bound less efficiently to vitamin D3-differentiated macrophages, leading to lower infection. Interestingly, IL-4 enhanced infection was reduced in D3-MDM by restriction of MR expression. Moreover, we detected moderate secretion of TNF-α, IL-1β, and IL-10 in D3-MDM, likely due to less MR engagement during DENV infection. CONCLUSIONS/SIGNIFICANCE: Our findings reveal a molecular mechanism by which vitamin D counteracts DENV infection and progression of severe disease, and indicates its potential relevance as a preventive or therapeutic candidate

SARS-CoV-2 Spike triggers barrier dysfunction and vascular leak via integrins and TGF-β signaling

Severe COVID-19 is associated with epithelial and endothelial barrier dysfunction within the lung as well as in distal organs. While it is appreciated that an exaggerated inflammatory response is associated with barrier dysfunction, the triggers of vascular leak are unclear. Here, we report that cell-intrinsic interactions between the Spike (S) glycoprotein of SARS-CoV-2 and epithelial/endothelial cells are sufficient to induce barrier dysfunction in vitro and vascular leak in vivo, independently of viral replication and the ACE2 receptor. We identify an S-triggered transcriptional response associated with extracellular matrix reorganization and TGF-β signaling. Using genetic knockouts and specific inhibitors, we demonstrate that glycosaminoglycans, integrins, and the TGF-β signaling axis are required for S-mediated barrier dysfunction. Notably, we show that SARS-CoV-2 infection caused leak in vivo, which was reduced by inhibiting integrins. Our findings offer mechanistic insight into SARS-CoV-2-triggered vascular leak, providing a starting point for development of therapies targeting COVID-19

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Depletion of CD8+ cells abolishes memory in acquired immunity against Chlamydia pneumoniae in BALB/c mice

The importance of T cells in Chlamydia pneumoniae infection in mice was assessed by comparing wild-type BALB/c mice with nude mice and mice depleted in vivo of either CD4+ or CD8+ T cells. Whereas wild-type mice cleared the primary infection in 3 weeks, nude mice were only able to restrict the infection and could not clear it during the observation period of 56 days. Nude mice exhibited a greater number of macrophages in their lungs and the pulmonary cells secreted a higher level of tumour necrosis factor-α (TNF-α) than wild-type mice. Depletion of CD4+ cells did not change the overall infection kinetics of the primary infection. However, depletion of CD8+ cells resulted in a slightly impaired clearance of the bacteria in the late stages of primary infection. To assess the role of the two T-cell subsets in the acquired immunity that develops during primary infection in wild-type BALB/c mice, in vivo depletions were performed during reinfection. Prior to reinfection, immunocompetent wild-type mice were infected and natural immunity was allowed to form. During reinfection, depletion of CD4+ cells did not have any effect on infection kinetics, whereas depletion of CD8+ cells abolished the protection, reverting the infection kinetics and bacterial load to the same levels found in wild-type mice during primary infection. These results show that T cells are necessary for clearing C. pneumoniae infection in mice. Furthermore, whereas neither of the two main T-cell subsets, separately, were essential for clearance of primary infection, the induced protective immunity was strongly CD8 dependent

Go/no-go decision in anaesthesia: wide variation in risk tolerance amongst anaesthetists

Background: The variability in risk tolerance in medicine is not well understood. Parallels are often drawn between aviation and anaesthesia. The aviation industry is perceived as culturally risk averse, and part of preflight checks involves a decision on whether the flight can operate. This is sometimes termed a go/no-go decision. This questionnaire study was undertaken to explore the equivalent go/no-go decision in anaesthesia. We presented anaesthetists with a range of situations in which additional risk might be expected and asked them to decide whether they would proceed with the case. Methods: An electronic questionnaire was distributed to anaesthetic colleagues of all grades in one National Health Service Trust. Eleven scenarios, all drawn from critical incident data, were presented. Participants were invited to consider whether they would proceed, how they would modify their anaesthetic technique, and to predict whether a colleague with similar experience would make the same decision. Textual responses were analysed qualitatively. Results: The scenario response rate was 28%. Consultants were significantly more likely to proceed than trainees. In no scenario was there absolute agreement over whether to proceed, even in scenarios where national guidelines would suggest a case should be cancelled. Thematic analysis suggested a wide variability in what anaesthetists consider acceptable or professional behaviour. Conclusions: It is clear that safety decisions cannot be made in isolation and that clinicians must consider operational requirements, such as throughput, when making a go/no-go decision. The level of variability in decision-making was surprising, particularly for scenarios that appeared to go against guidelines