ABSTRACT
BACKGROUND: Noninvasive ventilation (NIV) is beneficial in exacerbations of chronic obstructive pulmonary disease (COPD), but its effectiveness in pneumonia-associated respiratory failure is still controversial. In the current meta-analysis, we aimed to investigate whether the use of NIV before intubation in pneumonia improves the mortality and intubation rates of respiratory failure as compared to no use of NIV in adults. METHODS: We searched three databases from inception to December 2019. We included studies, in which pneumonia patients were randomized initially into either NIV-treated or non-NIV-treated groups. Five full-text publications, including 121 patients, reported eligible data for statistical analysis. RESULTS: With NIV the overall hospital mortality rate seemed lower in patients with pneumonia-associated respiratory failure, but this was not significant [odds ratio (OR) = 0.39; 95% confidence interval (CI): 0.13-1.14; P = 0.085]. In the intensive care unit, the mortality was significantly lower when NIV was applied compared to no NIV treatment (OR = 0.22; 95% CI: 0.07-0.75; P = 0.015). NIV also decreased mortality compared to no NIV in patient groups, which did not exclude patients with COPD (OR = 0.25; 95% CI: 0.08-0.74; P = 0.013). The need for intubation was significantly reduced in NIV-treated patients (OR = 0.22; 95% CI: 0.09-0.53; P = 0.001), which effect was more prominent in pneumonia patient groups not excluding patients with pre-existing COPD (OR = 0.13; 95% CI: 0.03-0.46; P = 0.002). CONCLUSION: NIV markedly decreases the death rate in the intensive care unit and reduces the need for intubation in patients with pneumonia-associated respiratory failure. The beneficial effects of NIV seem more pronounced in populations that include patients with COPD. Our findings suggest that NIV should be considered in the therapeutic guidelines of pneumonia, given that future clinical trials confirm the results of our meta-analysis. AVAILABILITY OF DATA AND MATERIALS: All data and materials generated during the current study are available from the corresponding author on reasonable request.
Subject(s)
Noninvasive Ventilation , Pneumonia , Respiratory Insufficiency , Adult , Hospital Mortality , Humans , Noninvasive Ventilation/methods , Pneumonia/complications , Pneumonia/therapy , Randomized Controlled Trials as Topic , Respiration, Artificial/methods , Respiratory Insufficiency/etiology , Respiratory Insufficiency/therapyABSTRACT
Emerging SARS-CoV-2 variants pose threats to vaccination campaigns against COVID-19. Being more transmissible than the original virus, the SARS-CoV-2 B.1.617 lineage, named the Delta variant, swept through the world in 2021. The mutations in the Delta's spike protein shift the protein towards a net positive electrostatic potential. To understand the key molecular drivers of the Delta infection, we investigate the cellular uptake of the Delta spike protein and Delta spike-bearing SARS-CoV-2 pseudoviruses. Specific in vitro modification of ACE2 and syndecan expression enabled us to demonstrate that syndecan-4, the syndecan isoform abundant in the lung, enhances the transmission of the Delta variant by attaching its mutated spike glycoprotein and facilitating its cellular entry. Compared to the wild-type spike, the Delta one shows a higher affinity towards heparan sulfate proteoglycans than towards ACE2. In addition to attachment to the polyanionic heparan sulfate chains, the Delta spike's molecular interactions with syndecan-4 also involve syndecan-4's cell-binding domain that mediates cell-to-cell adhesion. Regardless of the complexity of these interactions, exogenously added heparin blocks Delta's cellular entry as efficiently as syndecan-4 knockdown. Therefore, a profound understanding of the molecular mechanisms underlying Delta infections enables the development of molecularly targeted yet simple strategies to reduce the Delta variant's spread.