Prognostic and Pathogenic Role of Angiopoietin-1 and -2 in Pneumonia

Serum angiopoietin-2/angiopoietin-1 ratio is associated with cardiovascular and all-cause mortality in peritoneal dialysis patients: a prospective cohort study

INTRODUCTION

Our objective was to examine the factors associated with the serum angiopoietin-2/angiopoietin-1 (Angpt-2/Angpt-1) ratio in peritoneal dialysis (PD) patients and to investigate the association between Angpt-2/Angpt-1 ratio and cardiovascular and all-cause mortality.

METHODS

Patients on PD who were prevalent between January 2014 and April 2015 in the center of Renji Hospital were enrolled. At the time of enrollment, serum and dialysate samples were collected to detect biochemical parameters, serum angiopoietin-2 and angiopoietin-1 levels. Patients were dichotomized into two groups according to a median of Angpt-2/Angpt-1 ratio and followed up prospectively until the end of the study.

RESULTS

A total of 325 patients were enrolled, including 168 males (51.7%) with a mean age of 56.9 ± 14.2 years and a median PD duration of 32.4 (9.8-55.9) months. Multiple linear regression showed pulse pressure (β = 0.206, p < .001) and high-sensitivity C-reactive protein (hs-CRP) (β = 0.149, p = .011) were positively correlated with serum Angpt-2/Angpt-1 ratio, while residual renal function (RRF) (β= -0.219, p < .001) was negatively correlated with serum Angpt-2/Angpt-1 ratio. Multivariate Cox regression analysis showed the high serum Angpt-2/Angpt-1 ratio was an independent predictor of cardiovascular mortality (hazard ratio (HR)=2.467, 95% confidence interval (CI) 1.243-4.895, p = .010) and all-cause mortality (HR = 1.486, 95%CI 1.038-2.127, p = .031). In further subgroup analysis by gender, a significant association was shown in high Angpt-2/Angpt-1 ratio with all-cause mortality in male (p < .05), but not in female patients (p>.05).

CONCLUSIONS

High Angpt-2/Angpt-1 ratio is an independent risk factor for cardiovascular and all-cause mortality in PD patients.

Angiopoietin-1 attenuates lipopolysaccharide-induced endotoxemia in a Hirschsprung's disease murine model by improving intestinal vascular integrity: implications for treating postoperative Hirschsprung-associated enterocolitis

PURPOSE

Angiopoietin-1 (Ang1) mitigates inflammation as a proangiogenic growth factor. Action of Ang1 on lipopolysaccharide (LPS)-induced endotoxemic inflammation was investigated in endothelin receptor-B null Hirschsprung's disease mice (KO).

METHODS

LPS or saline was injected intraperitoneally in KO (KO-LPS; n = 9, KO-sal; n = 5) and wild-type (WT) (WT-LPS; n = 6, WT-sal; n = 6) pups obtained within 24 h of birth. Normoganglionic terminal ileum harvested 6 h after LPS was used for RNA extraction and histology. IL-1β, SELE, VEGFA, Ang1, Angiopoietin-2 (Ang2), and TIE2 expression analyzed by quantitative polymerase chain reaction (qPCR), vascular permeability assessed by the Miles assay, severity of inflammation, and immunofluorescence for phospho-TIE2 and VE-cadherin were used to assess endothelial cell contact integrity and compared with KO pups pretreated with intraperitoneal Ang1 [Ang1(KO-LPS); n = 5] or saline [sal(KO-LPS); n = 6] 2 h before LPS.

RESULTS

KO-LPS pups showed significantly increased inflammation (p < 0.05) and expression of IL-1β, SELE, VEGFA, and Ang2 (p = 0.019, 0.003, 0.008 and < 0.0001, respectively); expression of Ang1 and TIE2 remained unchanged when compared with KO-saline. In Ang1(KO-LPS) ileum, changes seen in sal(KO-LPS) were eliminated and phospho-TIE2 and VE-cadherin fluorescence increased.

CONCLUSION

Ang1 successfully attenuated LPS-induced normoganglionic intestinal inflammation, downregulated pro-inflammatory genes, and improved vascular barrier integrity in KO pups.

Molecular Phenotypes of Acute Respiratory Distress Syndrome in the ROSE Trial Have Differential Outcomes and Gene Expression Patterns That Differ at Baseline and Longitudinally over Time

Rationale: Two molecular phenotypes have been identified in acute respiratory distress syndrome (ARDS). In the ROSE (Reevaluation of Systemic Early Neuromuscular Blockade) trial of cisatracurium in moderate to severe ARDS, we addressed three unanswered questions: 1) Do the same phenotypes emerge in a more severe ARDS cohort with earlier recruitment; 2) Do phenotypes respond differently to neuromuscular blockade? and 3) What biological pathways most differentiate inflammatory phenotypes?Methods: We performed latent class analysis in ROSE using preenrollment clinical and protein biomarkers. In a subset of patients (n = 134), we sequenced whole-blood RNA using enrollment and Day 2 samples and performed differential gene expression and pathway analyses. Informed by the differential gene expression analysis, we measured additional plasma proteins and evaluated their abundance relative to gene expression amounts.Measurements and Main Results: In ROSE, we identified the hypoinflammatory (60.4%) and hyperinflammatory (39.6%) phenotypes with similar biological and clinical characteristics as prior studies, including higher mortality at Day 90 for the hyperinflammatory phenotype (30.3% vs. 61.6%; P < 0.0001). We observed no treatment interaction between the phenotypes and randomized groups for mortality. The hyperinflammatory phenotype was enriched for genes associated with innate immune response, tissue remodeling, and zinc metabolism at Day 0 and collagen synthesis and neutrophil degranulation at Day 2. Longitudinal changes in gene expression patterns differed dependent on survivorship. For most highly expressed genes, we observed correlations with their corresponding plasma proteins' abundance. However, for the class-defining plasma proteins in the latent class analysis, no correlation was observed with their corresponding genes' expression.Conclusions: The hyperinflammatory and hypoinflammatory phenotypes have different clinical, protein, and dynamic transcriptional characteristics. These findings support the clinical and biological potential of molecular phenotypes to advance precision care in ARDS.

Serum Angiopoietin-2 level increase differs between polytraumatized patients with and without central nervous system injuries

Since endothelial cells rapidly release Angiopoietin-2 (Ang-2) in response to vascular injury and inflammatory stimuli, we aimed to investigate if its serum levels increase in polytraumatized patients. Our cohort study evaluated 28 blunt polytrauma survivors (mean age, 38.4 years; median ISS, 34) who were directly admitted to our level I trauma center in 2018. We assessed the serum Ang-2 level at admission and on days 1, 3, 5, 7, and 10 during hospitalization. Ang-2 was released into the circulation immediately after polytrauma. At admission (day 0), it amounted to 8286 ± 5068 pg/mL, three-and-a-half times the reference value of 2337 ± 650 pg/mL assessed in a healthy control group. Subgroup analysis provided a higher mean Ang-2 level in the CNSI group combining all patients suffering a brain or spinal cord injury compared to the non-CNSI group solely on day 0 [11083 ± 5408 pg/mL versus 3963 ± 2062 pg/mL; p < 0.001]. Whereas the mean Ang-2 level increased only in the non-CNSI group from day 0 to day 3 (p = 0.009), the respective curves showed similar continuous decreases starting with day 3. Multivariate logistic regression analysis revealed an association between the Ang-2 day 0 level and the presence of a CNSI (OR = 1.885; p = 0.048). ROC analysis provided a cutoff level of 5352 pg/mL. In our study group, serum Ang-2 levels assessed at admission differed between polytraumatized patients with and without brain or spinal cord injuries. Based on our findings, we consider serum Ang-2 levels an effective biomarker candidate for indicating CNSI in these patients at admission, worthy of further evaluation in large multicenter studies.

John AL. Mast cell activation in lungs during SARS-CoV-2 infection associated with lung pathology and severe COVID-19

Lung inflammation is a hallmark of Coronavirus disease 2019 (COVID-19) in patients who are severely ill, and the pathophysiology of disease is thought to be immune mediated. Mast cells (MCs) are polyfunctional immune cells present in the airways, where they respond to certain viruses and allergens and often promote inflammation. We observed widespread degranulation of MCs during acute and unresolved airway inflammation in SARS-CoV-2-infected mice and nonhuman primates. Using a mouse model of MC deficiency, MC-dependent interstitial pneumonitis, hemorrhaging, and edema in the lung were observed during SARS-CoV-2 infection. In humans, transcriptional changes in patients requiring oxygen supplementation also implicated cells with a MC phenotype in severe disease. MC activation in humans was confirmed through detection of MC-specific proteases, including chymase, the levels of which were significantly correlated with disease severity and with biomarkers of vascular dysregulation. These results support the involvement of MCs in lung tissue damage during SARS-CoV-2 infection in animal models and the association of MC activation with severe COVID-19 in humans, suggesting potential strategies for intervention.

EVALUATION OF CYFRA 21-1, ANGIOPOETIN-2, PENTRAXIN-3, SRAGE, IL-6, AND IL-10 IN POLYTRAUMATIZED PATIENTS WITH CONCOMITANT THORACIC TRAUMA-HELPFUL MARKERS TO PREDICT PNEUMONIA?

ABSTRACT

Background: Pneumonia is a frequent complication after polytrauma. This study aims to evaluate the ability of different serum markers to identify patients at risk of developing pneumonia after polytrauma. Methods: A retrospective analysis of prospectively collected data in polytraumatized patients with concomitant thoracic trauma (Injury Severity Score ≥16, Abbreviated Injury Scale Thorax ≥ 3) was performed. The study cohort was divided into patients with and without pneumonia during the clinical course. Serum levels of lung epithelial (CYFRA 21-1), endothelial (Ang-2), and inflammatory (PTX-3, sRAGE, IL-6, IL-10) markers were measured upon arrival in the trauma room and on days 2 and 5. Results: A total of 73 patients and 16 healthy controls were included in this study. Of these, 20 patients (27.4%) developed pneumonia. Polytraumatized patients showed significantly increased CYFRA 21-1 levels with a distinct peak after admission compared with healthy controls. Serum PTX-3 significantly increased on day 2 in polytraumatized patients compared with healthy controls. Injury Severity Score and demographic parameters were comparable between both groups (pneumonia vs. no pneumonia). No statistically significant difference could be observed for serum levels of CYFRA 21-1, Ang-2, PTX-3, sRAGE, IL-6, and IL-10 between the groups (pneumonia vs. no pneumonia) on all days. Logistic regression revealed a combination of IL-6, IL-10, sRAGE, and PTX-3 to be eventually helpful to identify patients at risk of developing pneumonia and our newly developed score was significantly higher on day 0 in patients developing pneumonia ( P < 0.05). Conclusion: The investigated serum markers alone are not helpful to identify polytraumatized patients at risk of developing pneumonia, while a combination of IL-6, IL-10, PTX-3, and sRAGE might be.

Endothelial Damage, Neutrophil Extracellular Traps and Platelet Activation in COVID-19 vs. Community-Acquired Pneumonia: A Case-Control Study

COVID-19 has been a diagnostic and therapeutic challenge. It has marked a paradigm shift when considering other types of pneumonia etiology. We analyzed the biomarkers related to endothelial damage and immunothrombosis in COVID-19 in comparison to community-acquired pneumonia (CAP) through a case-control study of 358 patients with pneumonia (179 hospitalized with COVID-19 vs. 179 matched hospitalized with CAP). Endothelial damage markers (endothelin and proadrenomedullin), neutrophil extracellular traps (NETs) (citrullinated-3 histone, cell-free DNA), and platelet activation (soluble P-selectin) were measured. In-hospital and 1-year follow-up outcomes were evaluated. Endothelial damage, platelet activation, and NET biomarkers are significantly higher in CAP compared to COVID-19. In-hospital mortality in COVID-19 was higher compared to CAP whereas 1-year mortality and cardiovascular complications were higher in CAP. In the univariate analysis (OR 95% CIs), proADM and endothelin were associated with in-hospital mortality (proADM: CAP 3.210 [1.698-6.070], COVID-19 8.977 [3.413-23.609]; endothelin: CAP 1.014 [1.006-1.022], COVID-19 1.024 [1.014-1.034]), in-hospital CVE (proADM: CAP 1.623 [1.080-2.439], COVID-19 2.146 [1.186-3.882]; endothelin: CAP 1.005 [1.000-1.010], COVID-19 1.010 [1.003-1.018]), and 1-year mortality (proADM: CAP 2.590 [1.644-4.080], COVID-19 13.562 [4.872-37.751]; endothelin: CAP 1.008 [1.003-1.013], COVID-19 1.026 [1.016-1.037]). In conclusion, COVID-19 and CAP showed different expressions of endothelial damage and NETs. ProADM and endothelin are associated with short- and long-term mortality.

Defining the role of host biomarkers in the diagnosis and prognosis of the severity of childhood pneumonia: a prospective cohort study

Reliable tools to inform outpatient management of childhood pneumonia in resource-limited settings are needed. We investigated the value added by biomarkers of the host infection response to the performance of the Liverpool quick Sequential Organ Failure Assessment score (LqSOFA), for triage of children presenting with pneumonia to a primary care clinic in a refugee camp on the Thailand-Myanmar border. 900 consecutive presentations of children aged ≤ 24 months meeting WHO pneumonia criteria were included. The primary outcome was receipt of supplemental oxygen. We compared discrimination of a clinical risk score (LqSOFA) to markers of endothelial injury (Ang-1, Ang-2, sFlt-1), immune activation (CHI3L1, IP-10, IL-1ra, IL-6, IL-8, IL-10, sTNFR-1, sTREM-1), and inflammation (CRP, PCT), and quantified the net benefit of including biomarkers alongside LqSOFA. We evaluated the differential contribution of LqSOFA and host biomarkers to the diagnosis and prognosis of pneumonia severity. 49/900 (5.4%) presentations met the primary outcome. Discrimination of LqSOFA and Ang-2, the best performing biomarker, were comparable (AUC 0.82 [95% CI 0.76-0.88] and 0.81 [95% CI 0.74-0.87] respectively). Combining Ang-2 with LqSOFA improved discrimination (AUC 0.91; 95% CI 0.87-0.94; p < 0.001), and resulted in greater net benefit, with 10-30% fewer children who required oxygen supplementation incorrectly identified as safe for community-based management. Ang-2 had greater prognostic utility than LqSOFA to identify children requiring supplemental oxygen later in their illness course. Combining Ang-2 and LqSOFA could guide referrals of childhood pneumonia from resource-limited community settings. Further work on test development and integration into patient triage is required.

The Global Burden of Community-Acquired Pneumonia in Adults, Encompassing Invasive Pneumococcal Disease and the Prevalence of Its Associated Cardiovascular Events, with a Focus on Pneumolysin and Macrolide Antibiotics in Pathogenesis and Therapy

Despite innovative advances in anti-infective therapies and vaccine development technologies, community-acquired pneumonia (CAP) remains the most persistent cause of infection-related mortality globally. Confronting the ongoing threat posed by Streptococcus pneumoniae (the pneumococcus), the most common bacterial cause of CAP, particularly to the non-immune elderly, remains challenging due to the propensity of the elderly to develop invasive pneumococcal disease (IPD), together with the predilection of the pathogen for the heart. The resultant development of often fatal cardiovascular events (CVEs), particularly during the first seven days of acute infection, is now recognized as a relatively common complication of IPD. The current review represents an update on the prevalence and types of CVEs associated with acute bacterial CAP, particularly IPD. In addition, it is focused on recent insights into the involvement of the pneumococcal pore-forming toxin, pneumolysin (Ply), in subverting host immune defenses, particularly the protective functions of the alveolar macrophage during early-stage disease. This, in turn, enables extra-pulmonary dissemination of the pathogen, leading to cardiac invasion, cardiotoxicity and myocardial dysfunction. The review concludes with an overview of the current status of macrolide antibiotics in the treatment of bacterial CAP in general, as well as severe pneumococcal CAP, including a consideration of the mechanisms by which these agents inhibit the production of Ply by macrolide-resistant strains of the pathogen.

Loss of endothelial CFTR drives barrier failure and edema formation in lung infection and can be targeted by CFTR potentiation

Pneumonia is the most common cause of the acute respiratory distress syndrome (ARDS). Here, we identified loss of endothelial cystic fibrosis transmembrane conductance regulator (CFTR) as an important pathomechanism leading to lung barrier failure in pneumonia-induced ARDS. CFTR was down-regulated after Streptococcus pneumoniae infection ex vivo or in vivo in human or murine lung tissue, respectively. Analysis of isolated perfused rat lungs revealed that CFTR inhibition increased endothelial permeability in parallel with intracellular chloride ion and calcium ion concentrations ([Cl^-]_i and [Ca²⁺]_i). Inhibition of the chloride ion-sensitive with-no-lysine kinase 1 (WNK1) protein with tyrphostin 47 or WNK463 replicated the effect of CFTR inhibition on endothelial permeability and endothelial [Ca²⁺]_i, whereas WNK1 activation by temozolomide attenuated it. Endothelial [Ca²⁺]_i transients and permeability in response to inhibition of either CFTR or WNK1 were prevented by inhibition of the cation channel transient receptor potential vanilloid 4 (TRPV4). Mice deficient in Trpv4 (Trpv4^-/-) developed less lung edema and protein leak than their wild-type littermates after infection with S. pneumoniae. The CFTR potentiator ivacaftor prevented lung CFTR loss, edema, and protein leak after S. pneumoniae infection in wild-type mice. In conclusion, lung infection caused loss of CFTR that promoted lung edema formation through intracellular chloride ion accumulation, inhibition of WNK1, and subsequent disinhibition of TRPV4, resulting in endothelial calcium ion influx and vascular barrier failure. Ivacaftor prevented CFTR loss in the lungs of mice with pneumonia and may, therefore, represent a possible therapeutic strategy in people suffering from ARDS due to severe pneumonia.

Advanced development and mechanism of sepsis-related acute respiratory distress syndrome

The introduction of the Sepsis 3.0 guidelines in 2016 improved our understanding of sepsis diagnosis and therapy. Personalized treatment strategies and nursing methods for sepsis patients are recommended in the "Save Sepsis Campaign" in 2021. However, mortality in sepsis patients remains high. Patients with sepsis-related acute respiratory distress syndrome account for around 30% of them, with fatality rates ranging from 30 to 40%. Pathological specimens from individuals with sepsis-related ARDS frequently demonstrate widespread alveolar damage, and investigations have revealed that pulmonary epithelial and pulmonary endothelial injury is the underlying cause. As a result, the purpose of this work is to evaluate the mechanism and research progress of pulmonary epithelial and pulmonary endothelial damage in sepsis-related ARDS, which may provide new directions for future research, diagnosis, and therapy.

N-myc and STAT interactor is a novel biomarker of severity in community-acquired pneumonia: a prospective study

Objectives

To tested the ability of N-myc and STAT interactor (NMI) levels in patients with community-acquired pneumonia (CAP) to predict the severity of the disease.

Methods

Prospective observational analysis of patients with CAP was performed. The NMI levels in serum of 394 CAP patients on admission were measured by immunoassay. Thirty-day mortality and intensive care unit (ICU) admission were set as clinical outcomes. The predicting value of NMI for clinical outcomes was determined by receiver operating characteristic curve and logistic regression analysis. The internal validity was assessed using cross-validation with bootstrap resampling.

Results

NMI was an independent risk factor for both 30-day mortality and admission to ICU for CAP patients. The area under curve (AUC) of NMI to predict mortality was 0.91 (95% CI: 0.86–0.96), and that to predict ICU admission was 0.92 (95% CI: 0.88–0.97), significantly higher than that of other biomarkers including procalcitonin and C-reactive protein. The proportion of clinical outcomes notably rose as NMI levels elevated (P < 0.001). The AUCs of the new score systems including NMI (N-PSI and N-CURB65 score) to predict outcomes were significantly higher than the original score systems.

Conclusions

NMI is a novel biomarker for predicting CAP severity superior to former biomarkers in 30-day mortality and ICU admission.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02139-x.

Adjunctive therapy with the Tie2 agonist Vasculotide reduces pulmonary permeability in Streptococcus pneumoniae infected and mechanically ventilated mice

Community acquired pneumonia, mainly caused by Streptococcus pneumoniae (S.pn.), is a common cause of death worldwide. Despite adequate antibiotic therapy, pneumococcal pneumonia can induce pulmonary endothelial hyperpermeability leading to acute lung injury, which often requires mechanical ventilation (MV) causing ventilator-induced lung injury (VILI). Endothelial stabilization is mediated by angiopoietin-1 induced Tie2 activation. PEGylated (polyethylene glycol) Tie2-agonist Vasculotide (VT) mimics Angiopietin-1 effects. Recently, VT has been shown to reduce pulmonary hyperpermeability in murine pneumococcal pneumonia. The aim of this study was to determine whether VT reduces lung damage in S.pn. infected and mechanically ventilated mice. Pulmonary hyperpermeability, immune response and bacterial load were quantified in S.pn. infected mice treated with Ampicillin + /−VT and undergoing six hours of MV 24 h post infection. Histopathological lung changes, Tie2-expression and -phosphorylation were evaluated. VT did not alter immune response or bacterial burden, but interestingly combination treatment with ampicillin significantly reduced pulmonary hyperpermeability, histological lung damage and edema formation. Tie2-mRNA expression was reduced by S.pn. infection and/or MV but not restored by VT. Moreover, Tie2 phosphorylation was not affected by VT. These findings indicate that VT may be a promising adjunctive treatment option for prevention of VILI in severe pneumococcal pneumonia.

Unmet needs in pneumonia research: a comprehensive approach by the CAPNETZ study group

Introduction

Despite improvements in medical science and public health, mortality of community-acquired pneumonia (CAP) has barely changed throughout the last 15 years. The current SARS-CoV-2 pandemic has once again highlighted the central importance of acute respiratory infections to human health. The “network of excellence on Community Acquired Pneumonia” (CAPNETZ) hosts the most comprehensive CAP database worldwide including more than 12,000 patients. CAPNETZ connects physicians, microbiologists, virologists, epidemiologists, and computer scientists throughout Europe. Our aim was to summarize the current situation in CAP research and identify the most pressing unmet needs in CAP research.

Methods

To identify areas of future CAP research, CAPNETZ followed a multiple-step procedure. First, research members of CAPNETZ were individually asked to identify unmet needs. Second, the top 100 experts in the field of CAP research were asked for their insights about the unmet needs in CAP (Delphi approach). Third, internal and external experts discussed unmet needs in CAP at a scientific retreat.

Results

Eleven topics for future CAP research were identified: detection of causative pathogens, next generation sequencing for antimicrobial treatment guidance, imaging diagnostics, biomarkers, risk stratification, antiviral and antibiotic treatment, adjunctive therapy, vaccines and prevention, systemic and local immune response, comorbidities, and long-term cardio-vascular complications.

Conclusion

Pneumonia is a complex disease where the interplay between pathogens, immune system and comorbidities not only impose an immediate risk of mortality but also affect the patients’ risk of developing comorbidities as well as mortality for up to a decade after pneumonia has resolved. Our review of unmet needs in CAP research has shown that there are still major shortcomings in our knowledge of CAP.

TPGS-based and S-thanatin functionalized nanorods for overcoming drug resistance in Klebsiella pneumonia

Tigecycline is regarded as the last line of defense to combat multidrug-resistant Klebsiella pneumoniae. However, increasing utilization has led to rising drug resistance and treatment failure. Here, we design a D-alpha tocopheryl polyethylene glycol succinate-modified and S-thanatin peptide-functionalized nanorods based on calcium phosphate nanoparticles for tigecycline delivery and pneumonia therapy caused by tigecycline-resistant Klebsiella pneumoniae. After incubation with bacteria, the fabricated nanorods can enhance tigecycline accumulation in bacteria via the inhibitory effect on efflux pumps exerted by D-alpha tocopheryl polyethylene glycol succinate and the targeting capacity of S-thanatin to bacteria. The synergistic antibacterial capacity between S-thanatin and tigecycline further enhances the antibacterial activity of nanorods, thus overcoming the tigecycline resistance of Klebsiella pneumoniae. After intravenous injection, nanorods significantly reduces the counts of white blood cells and neutrophils, decreases bacterial colonies, and ameliorates neutrophil infiltration events, thereby largely increasing the survival rate of mice with pneumonia. These findings may provide a therapeutic strategy for infections caused by drug-resistant bacteria.

Overproduction of efflux pumps represents an important mechanism of Klebsiella pneumonia resistance to tigecycline. Here, the authors design TPGS- and S-thanatin functionalized nanorods loaded with tigecycline to increase drug accumulation inside bacteria and overcome bacterial resistance.

Nebulization Therapy with Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes for COVID-19 Pneumonia

Background

Scientists have been facing numerous challenges in the development of an effective therapeutic strategy for the treatment of COVID-19 pneumonia. Several studies have suggested that improving patient immunity and reducing lung injury induced by SARS-CoV-2 may be effective for treating patients with COVID-19.

Methods

A pilot trial of nebulization therapy with exosomes of mesenchymal stem cells (MSCs) was performed on seven patients with COVID-19 pneumonia. Exosomes secreted from MSCs were collected and purified using multiple ultrafiltration steps. All patients were treated with nebulization of MSC-derived exosomes, and primary safety and efficacy outcomes were evaluated.

Results

Our clinical study demonstrated that nebulization of MSC-derived exosomes is a novel method that might be utilized in the treatment of COVID-19 pneumonia. Nebulization of MSC-derived exosomes did not induce acute allergic or secondary allergic reactions but did promote the absorption of pulmonary lesions and reduce the duration of hospitalization for mild cases of COVID-19 pneumonia.

Conclusions

Nebulization of MSC-derived exosomes is a safe, effective, and simple method, and their application at the beginning of treatment may be more beneficial.

Trial Registration

Chinese Clinical Trial Registry, ChiCTR2000030261. Registered on 26 February 2020.

Graphical Abstract

Prognostic Value of Histidine-Rich Glycoprotein for Community-Acquired Pneumonia

Purpose

Histidine-rich glycoprotein (HRG) is abundant in serum and has been implicated in several processes including blood coagulation and immune response. This prospective study is aimed at exploring HRG as a biomarker in patients hospitalized for community-acquired pneumonia (CAP).

Methods

A total of 160 patients (73 severe CAP, 57 nonsevere CAP), and 30 healthy controls were enrolled in 2019. Demographic and clinical data were recorded for all patients. Serum HRG concentration was measured upon admission using ELISA.

Results

HRG levels were significantly lower in severe CAP patients compared with other groups, regardless of etiology, and were negatively correlated with serum interleukin-6 and disease severity index scores. Combination of CURB-65, PSI, and APACHE II scores with HRG values significantly improved the accuracy of predicting 30-day mortality in these patients. Cox regression analysis showed that HRG could serve as an independent risk factor for 30-day mortality. Notably, patients with HRG ≤ 16.92 μg/mL had significantly lower cumulative survival than those with HRG > 16.92 μg/mL.

Conclusion

Serum HRG levels are lower in patients with severe CAP and are negatively correlated with disease severity scores. Measurement of HRG upon admission can provide valuable prognostic information for patients with CAP.

Efficacy and Safety of LY3127804, an Anti-Angiopoietin-2 Antibody, in a Randomized, Double-Blind, Placebo-Controlled Clinical Trial in Patients Hospitalized with Pneumonia and Presumed or Confirmed COVID-19

BACKGROUND

Severe cases of coronavirus disease 2019 (COVID-19) are characterized by progressive respiratory failure and the development of acute respiratory distress syndrome (ARDS), with high mortality rates for patients requiring mechanical ventilation. Levels of the vascular growth factor Angiopoietin 2 (Ang2) in plasma have been strongly correlated with increased ARDS risk in patients with pneumonia or sepsis. The intent of this study was to determine whether LY3127804, an anti-Ang2 monoclonal antibody, could reduce the need for mechanical ventilation among patients admitted to the hospital with pneumonia and presumed or confirmed COVID-19.

METHODS

Patients admitted to hospital with confirmed pneumonia, presumed or confirmed COVID-19, and infiltrates on chest imaging and/or oxygen saturation of ≤ 95% on room air were stratified by age group (< 65 years and ≥ 65 years), sex, and site and randomly assigned 1:1 within each stratum to receive either LY3127804 (20 mg/kg) or placebo on Day 1 and possibly on Day 15. The primary end point for this study was number of days in which a patient did not require a ventilator over the 28-day study period.

RESULTS

Interim analysis assessed study futility after 95 randomized patients had 28-day data available and showed no benefit of LY3127804 in reducing the number of ventilator days over placebo. The study was subsequently terminated.

CONCLUSION

LY3127804 treatment did not decrease the need for ventilator usage in patients hospitalized with pneumonia and presumed or confirmed COVID-19.

ClinicalTrials.gov identifier

NCT04342897

Requirement of respiratory support in acute bronchiolitis in infants is linked to endothelial and neutrophil activation

BACKGROUND

Evidence shows that activation of pulmonary vascular endothelium and neutrophils are involved in the pathophysiology of acute bronchiolitis. We hypothesized that levels of markers of endothelial activation and leukocyte counts are associated with requirement and duration of respiratory support.

METHODS

Thirty-four infants with bronchiolitis and eight controls were included. Nasopharyngeal swabs and blood samples were taken at admission. Serum levels of Angiopoietin (Ang)-1, Ang-2, sP-selectin, sE-selectin, vascular cell adhesion molecule-1 (sVCAM-1), intercellular adhesion molecule-1 (sICAM-1), and leukocyte counts were measured. For univariate analysis, bronchiolitis cases were grouped into two groups, namely those not requiring and those requiring any form of respiratory support. To control for known risk factors for poor outcome (i.e., age, prematurity, and congenital heart disease), and for days post symptom onset, linear regression analysis was performed with duration of any type of respiratory support in days.

RESULTS

Ang-2 levels, Ang-2/Ang-1 ratios, sE-selectin levels, immature neutrophil count, and neutrophil/lymphocyte ratio (NLR) were higher in acute bronchiolitis versus controls. Ang-2, and NLR levels were significantly higher, and lymphocyte counts significantly lower, in infants that required respiratory support versus those that did not. Ang-2 levels (β: .32, 95% confidence interval [CI]: 0.19-1.19) and NLR (β: .68, 95% CI: 0.17-1.19) were positive predictors for the duration of respiratory support.

CONCLUSIONS

Markers of endothelial and neutrophil activation are associated with respiratory support for acute bronchiolitis. Admission Ang-2 levels and NLR may be promising markers to determine requirement of respiratory support and deserve further study.

COVID-19: A Redox Disease-What a Stress Pandemic Can Teach Us About Resilience and What We May Learn from the Reactive Species Interactome About Its Treatment

Significance: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus causing coronavirus disease 2019 (COVID-19), affects every aspect of human life by challenging bodily, socioeconomic, and political systems at unprecedented levels. As vaccines become available, their distribution, safety, and efficacy against emerging variants remain uncertain, and specific treatments are lacking. Recent Advances: Initially affecting the lungs, COVID-19 is a complex multisystems disease that disturbs the whole-body redox balance and can be long-lasting (Long-COVID). Numerous risk factors have been identified, but the reasons for variations in susceptibility to infection, disease severity, and outcome are poorly understood. The reactive species interactome (RSI) was recently introduced as a framework to conceptualize how cells and whole organisms sense, integrate, and accommodate stress. Critical Issues: We here consider COVID-19 as a redox disease, offering a holistic perspective of its effects on the human body, considering the vulnerability of complex interconnected systems with multiorgan/multilevel interdependencies. Host/viral glycan interactions underpin SARS-CoV-2's extraordinary efficiency in gaining cellular access, crossing the epithelial/endothelial barrier to spread along the vascular/lymphatic endothelium, and evading antiviral/antioxidant defences. An inflammation-driven "oxidative storm" alters the redox landscape, eliciting epithelial, endothelial, mitochondrial, metabolic, and immune dysfunction, and coagulopathy. Concomitantly reduced nitric oxide availability renders the sulfur-based redox circuitry vulnerable to oxidation, with eventual catastrophic failure in redox communication/regulation. Host nutrient limitations are crucial determinants of resilience at the individual and population level. Future Directions: While inflicting considerable damage to health and well-being, COVID-19 may provide the ultimate testing ground to improve the diagnosis and treatment of redox-related stress diseases. "Redox phenotyping" of patients to characterize whole-body RSI status as the disease progresses may inform new therapeutic approaches to regain redox balance, reduce mortality in COVID-19 and other redox diseases, and provide opportunities to tackle Long-COVID. Antioxid. Redox Signal. 35, 1226-1268.

Neutrophil-Dependent Immunity During Pulmonary Infections and Inflammations

Rapid recruitment of neutrophils to an inflamed site is one of the hallmarks of an effective host defense mechanism. The main pathway through which this happens is by the innate immune response. Neutrophils, which play an important part in innate immune defense, migrate into lungs through the modulation actions of chemokines to execute a variety of pro-inflammatory functions. Despite the importance of chemokines in host immunity, little has been discussed on their roles in host immunity. A holistic understanding of neutrophil recruitment, pattern recognition pathways, the roles of chemokines and the pathophysiological roles of neutrophils in host immunity may allow for new approaches in the treatment of infectious and inflammatory disease of the lung. Herein, this review aims at highlighting some of the developments in lung neutrophil-immunity by focusing on the functions and roles of CXC/CC chemokines and pattern recognition receptors in neutrophil immunity during pulmonary inflammations. The pathophysiological roles of neutrophils in COVID-19 and thromboembolism have also been summarized. We finally summarized various neutrophil biomarkers that can be utilized as prognostic molecules in pulmonary inflammations and discussed various neutrophil-targeted therapies for neutrophil-driven pulmonary inflammatory diseases.

Mechanism of Phosgene-Induced Acute Lung Injury and Treatment Strategy

Phosgene (COCl₂) was once used as a classic suffocation poison and currently plays an essential role in industrial production. Due to its high toxicity, the problem of poisoning caused by leakage during production, storage, and use cannot be ignored. Phosgene mainly acts on the lungs, causing long-lasting respiratory depression, refractory pulmonary edema, and other related lung injuries, which may cause acute respiratory distress syndrome or even death in severe cases. Due to the high mortality, poor prognosis, and frequent sequelae, targeted therapies for phosgene exposure are needed. However, there is currently no specific antidote for phosgene poisoning. This paper reviews the literature on the mechanism and treatment strategies to explore new ideas for the treatment of phosgene poisoning.

Passive muscle heating attenuates the decline in vascular function caused by limb disuse

Limb disuse has profound negative consequences on both vascular and skeletal muscle health. The purpose of this investigation was to determine whether repeated application of passive heat, applied to the knee extensor muscles, could mitigate the detrimental effects of limb disuse on vascular function. This was a randomized, single-blinded placebo controlled trial. Twenty-one healthy volunteers (10 women, 11 men) underwent 10 days of unilateral lower limb immobilization and were randomized to receive either a daily 2 h sham (Imm) or heat treatment (Imm+H) using pulsed shortwave diathermy. Vascular function was assessed with Doppler ultrasound of the femoral artery and the passive leg movement technique. Biopsies of the vastus lateralis were also collected before and after the intervention. In Imm, femoral artery diameter (FAD) and PLM-induced hyperaemia (HYP) were reduced by 7.3% and 34.3%, respectively. Changes in both FAD (4% decrease; P = 0.0006) and HYP (7.8% increase; P = 0.003) were significantly attenuated in Imm+H. Vastus lateralis capillary density was not altered in either group. Immobilization significantly decreased expression of vascular endothelial growth factor (P = 0.006) and Akt (P = 0.001), and increased expression of angiopoietin 2 (P = 0.0004) over time, with no differences found between groups. Immobilization also upregulated elements associated with remodelling of the extracellular matrix, including matrix metalloproteinase 2 (P = 0.0046) and fibronectin (P = 0.0163), with no differences found between groups. In conclusion, limb immobilization impairs vascular endothelial function, but daily muscle heating via diathermy is sufficient to counteract this adverse effect. These are the first data to indicate that passive muscle heating mitigates disuse-induced vascular dysfunction. KEY POINTS: Limb disuse can be unavoidable for many of reasons (i.e. injury, bed rest, post-surgery), and can have significant adverse consequences for muscular and vascular health. We tested the hypothesis that declines in vascular function that result from lower limb immobilization could be mitigated by application of passive heat therapy. This report shows that 10 days of limb immobilization significantly decreases resistance artery diameter and vascular function, and that application of passive heat to the knee extensor muscle group each day for 2 h per day is sufficient to attenuate these declines. Additionally, muscle biopsy analyses showed that 10 days of heat therapy does not alter capillary density of the muscle, but upregulates multiple factors indicative of a vascular remodelling response. Our data demonstrate the utility of passive heat as a therapeutic tool to mitigate losses in lower limb vascular function that occur from disuse.

Blood leukocyte transcriptomes in gram-positive and gram-negative community-acquired pneumonia

BACKGROUND

Gram-positive and Gram-negative bacteria are the most common causative pathogens in community-acquired pneumonia (CAP) on the intensive care unit (ICU). The aim of this study was to determine whether the host immune response differs between Gram-positive and Gram-negative CAP upon ICU admission.

METHODS

Sixteen host response biomarkers providing insight in pathophysiological mechanisms implicated in sepsis and blood leukocyte transcriptomes were analysed in patients with CAP upon ICU admission in two tertiary hospitals in the Netherlands.

RESULTS

309 patients with CAP with a definite or probable likelihood (determined by predefined criteria) were included. A causative pathogen was determined in 74.4% of admissions. Patients admitted with Gram-positive CAP (n=90) were not different from those admitted with Gram-negative CAP (n=75) regarding demographics, chronic comorbidities, severity of disease and mortality. Host response biomarkers reflective of systemic inflammation, coagulation activation and endothelial cell function, as well as blood leukocytes transcriptomes, were largely similar between Gram-positive and Gram-negative CAP. Blood leukocyte transcriptomes were also similar in Gram-positive and Gram-negative CAP in two independent validation cohorts. On a pathogen-specific level, Streptococcus pneumoniae and Escherichia coli induced the most distinct host immune response.

CONCLUSION

Outcome and host response are similar in critically ill patients with CAP due to Gram-positive bacteria compared to Gram-negative bacteria.

Adipokines in metabolic and reproductive functions in birds: An overview of current knowns and unknowns

Adipose tissue is now recognized as an active endocrine organ, which synthesizes and secretes numerous peptides factors called adipokines. In mammals, they exert pleiotropic effects affecting energy metabolism but also fertility. In mammals, secretion of adipokines is altered in adipose tissue dysfunctions and may participate to obesity-associated disorders. Thus, adipokines are promising candidates both for novel pharmacological treatment strategies and as diagnostic tools. As compared to mammals, birds exhibit several unique physiological features, which make them an interesting model for comparative studies on endocrine control of metabolism and adiposity and reproductive functions. Some adipokines such as leptin and visfatin may have different roles in avian species as compared to mammals. In addition, some of them found in mammals such as CCL2 (chemokine ligand 2), resistin, omentin and FGF21 (Fibroblast Growth factor 21) have not yet been mapped to the chicken genome model and among its annotated gene models. This brief review aims to summarize data (structure, metabolic and reproductive roles and molecular mechanisms involved) related to main avian adipokines (leptin, adiponectin, visfatin, and chemerin) and we will briefly discuss the adipokines that are still lacking in avian species.

The role of angiopoietin-2 and surfactant protein-D levels in SARS-CoV-2-related lung injury: A prospective, observational, cohort study

Introduction

Coronavirus disease‐2019 (COVID‐19) is a respiratory disease whose clinical manifestation ranges from asymptomatic to severe respiratory failure. The purpose of this study was to investigate the place of serum surfactant‐D (SP‐D) and angiopoetin‐2 (Ang‐2) levels in predicting severity of disease in patients diagnosed with COVID‐19.

Methods

Sixty‐four patients diagnosed with COVID‐19 between September 2020 and February 2021, 50 patients diagnosed with community‐acquired pneumonia and a 50‐member healthy control group were included in the study. Plasma samples and clinical data were collected within 72 h after admission, during hospital stay. Serum SP‐D and Ang‐2 concentrations were measured using the enzyme‐linked immunosorbent assay.

Results

SP‐D and Ang‐2 levels were significantly higher in the mild–moderate pneumonia and severe/critical patient groups compared to the asymptomatic and noncomplicated COVID‐19 patients (p < 0.001 for all groups). Serum SP‐D and Ang‐2 levels of severe‐critical COVID‐19 patients were significantly higher than CAP patients (p < 0.001). Powerful correlation was present between clinical severity of COVID‐19 and SP‐D and Ang‐2 levels (r = 0.885 p < 0.001 and r = 0.913 p < 0.001, respectively). Cut‐off values of 37.7 ng/ml (AUC = 0.763, p < 0.001, 95% confidence interval [CI] = 0.667–0.860) for SP‐D and 4208.3 pg/ml (AUC = 0.659, p = 0.004, 95% CI = 0.554–0.763) for Ang‐2 were identified as predictors of COVID‐19 disease at receiver operating characteristic curve analysis.

Conclusion

SP‐D and Ang‐2 are predictive factors in differentiating COVID‐19 patients and determining severity of disease. These data may be important for the initiation of treatment in the early stage of the disease in patients with COVID‐19.

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All clinicians should be aware of cutaneous lesions of COVID‐19

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Such manifestations could be the first presentation of the infection or an indicator of the deterioration of the patient s wellbeing.

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Also, such dermatologic symptoms could be because of anti‐SARS‐CoV‐2 medications, expressing the need to monitor patients cautiously.

Carbonic Anhydrase IX and Hypoxia Promote Rat Pulmonary Endothelial Cell Survival During Infection

Low tidal volume ventilation protects the lung in mechanically ventilated patients. The impact of the accompanying permissive hypoxemia and hypercapnia on endothelial cell recovery from injury is poorly understood. Carbonic anhydrase IX (CA IX) is expressed in pulmonary microvascular endothelial cells (PMVECs), where it contributes to CO2 and pH homeostasis, bioenergetics and angiogenesis. We hypothesized that CA IX is important for PMVEC survival, and CA IX expression and release from PMVECs are increased during infection. While plasma CA IX was unchanged in human and rat pneumonia, there was a trend towards increasing CA IX in bronchoalveolar fluid of mechanically ventilated critically ill pneumonia patients and a significant increase in CA IX in lung tissue lysate of rat pneumonia. To investigate functional implications of the lung CA IX increase, we generated PMVEC cell lines harboring domain-specific CA IX mutations. Using these cells, we found that infection promotes intracellular expression, release and metalloproteinase-mediated extracellular cleavage of CA IX in PMVECs. Intracellular domain deletion uniquely impaired CA IX membrane localization. Loss of the CA IX intracellular domain promoted cell death following infection, suggesting the important role of intracellular domain in PMVEC survival. We also found that hypoxia improves survival, whereas hypercapnia reverses the protective effect of hypoxia, during infection. Thus, we report that: (1) CA IX increases in rat pneumonia lung; and, (2) the CA IX intracellular domain and hypoxia promote PMVEC survival during infection.

Signatures of mast cell activation are associated with severe COVID-19

Lung inflammation is a hallmark of Coronavirus disease 2019 (COVID-19) in severely ill patients and the pathophysiology of disease is thought to be immune-mediated. Mast cells (MCs) are polyfunctional immune cells present in the airways, where they respond to certain viruses and allergens, often promoting inflammation. We observed widespread degranulation of MCs during acute and unresolved airway inflammation in SARS-CoV-2-infected mice and non-human primates. In humans, transcriptional changes in patients requiring oxygen supplementation also implicated cells with a MC phenotype. MC activation in humans was confirmed, through detection of the MC-specific protease, chymase, levels of which were significantly correlated with disease severity. These results support the association of MC activation with severe COVID-19, suggesting potential strategies for intervention.

Extracellular Vesicles: Versatile Nanomediators, Potential Biomarkers and Therapeutic Agents in Atherosclerosis and COVID-19-Related Thrombosis

Cells convey information among one another. One instrument employed to transmit data and constituents to specific (target) cells is extracellular vesicles (EVs). They originate from a variety of cells (endothelial, immune cells, platelets, mesenchymal stromal cells, etc.), and consequently, their surface characteristics and cargo vary according to the paternal cell. The cargo could be DNA, mRNA, microRNA, receptors, metabolites, cytoplasmic proteins, or pathological molecules, as a function of which EVs exert different effects upon endocytosis in recipient cells. Recently, EVs have become important participants in a variety of pathologies, including atherogenesis and coronavirus disease 2019 (COVID-19)-associated thrombosis. Herein, we summarize recent advances and some of our own results on the role of EVs in atherosclerotic cardiovascular diseases, and discuss their potential to function as signaling mediators, biomarkers and therapeutic agents. Since COVID-19 patients have a high rate of thrombotic events, a special section of the review is dedicated to the mechanism of thrombosis and the possible therapeutic potential of EVs in COVID-19-related thrombosis. Yet, EV mechanisms and their role in the transfer of information between cells in normal and pathological conditions remain to be explored.

Comparison of host endothelial, epithelial and inflammatory response in ICU patients with and without COVID-19: a prospective observational cohort study

BACKGROUND

Analyses of blood biomarkers involved in the host response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral infection can reveal distinct biological pathways and inform development and testing of therapeutics for COVID-19. Our objective was to evaluate host endothelial, epithelial and inflammatory biomarkers in COVID-19.

METHODS

We prospectively enrolled 171 ICU patients, including 78 (46%) patients positive and 93 (54%) negative for SARS-CoV-2 infection from April to September, 2020. We compared 22 plasma biomarkers in blood collected within 24 h and 3 days after ICU admission.

RESULTS

In critically ill COVID-19 and non-COVID-19 patients, the most common ICU admission diagnoses were respiratory failure or pneumonia, followed by sepsis and other diagnoses. Similar proportions of patients in both groups received invasive mechanical ventilation at the time of study enrollment. COVID-19 and non-COVID-19 patients had similar rates of acute respiratory distress syndrome, severe acute kidney injury, and in-hospital mortality. While concentrations of interleukin 6 and 8 were not different between groups, markers of epithelial cell injury (soluble receptor for advanced glycation end products, sRAGE) and acute phase proteins (serum amyloid A, SAA) were significantly higher in COVID-19 compared to non-COVID-19, adjusting for demographics and APACHE III scores. In contrast, angiopoietin 2:1 (Ang-2:1 ratio) and soluble tumor necrosis factor receptor 1 (sTNFR-1), markers of endothelial dysfunction and inflammation, were significantly lower in COVID-19 (p < 0.002). Ang-2:1 ratio and SAA were associated with mortality only in non-COVID-19 patients.

CONCLUSIONS

These studies demonstrate that, unlike other well-studied causes of critical illness, endothelial dysfunction may not be characteristic of severe COVID-19 early after ICU admission. Pathways resulting in elaboration of acute phase proteins and inducing epithelial cell injury may be promising targets for therapeutics in COVID-19.

Serum Levels of Markers of Endothelial Activation Are Not Associated with a Positive Blood Culture in Surinamese Children with Suspected Severe Infection

BACKGROUND

Systemic serum levels of markers of endothelial activation are associated with infection. We hypothesize that levels of markers of endothelial activation are associated with the presence of a positive blood culture as a manifestation of a systemic infection in children with a suspected severe infection in Suriname.

METHODS

In this prospective observational cohort study, children between 1 month and 18 years of age suspected of severe infection as assessed by the threating physician, and in whom laboratory testing and blood culturing was performed before start of intravenous antibiotic treatment, were recruited at the emergency department of the Academic Hospital Paramaribo, Suriname. Serum was collected at blood culturing and after 48-72 h of admission. Serum was stored for measurement of levels of Angiopoietin (Ang)-1, Ang-2, soluble (s)P-selectin, sE-selectin, vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and platelet and endothelial cell adhesion molecule-1.

RESULTS

Fifty-one children were included of whom 10 had a positive blood culture. Baseline characteristics were similar between children with and without a positive blood culture. No significant differences in serum levels of the Angiopoietins or soluble cellular adhesion molecules between groups were observed at start of antibiotic treatment nor after 48-72 h.

CONCLUSIONS

The data from this study indicate that in children with severe infection, serum levels of markers of endothelial cell activation are not associated with a positive blood culture. Thus, having a positive bacterial blood culture may not be the only factor driving endothelial activation in this patient population.

Arginine vasopressin receptor 2 activation promotes microvascular permeability in sepsis

Methicillin-resistant Staphylococcus aureus (MRSA) sepsis is a severe condition associated with vascular leakage and poor prognosis. The hemodynamic management of sepsis targets hypotension, but there is no specific treatment available for vascular leakage. Arginine vasopressin (AVP) has been used in sepsis to promote vasoconstriction by activating AVP receptor 1 (V₁R). However, recent evidence suggests that increased fluid retention may be associated with the AVP receptor 2 (V₂R) activation worsening the outcome of sepsis. Hence, we hypothesized that the inhibition of V₂R activation ameliorates the severity of microvascular hyperpermeability during sepsis. The hypothesis was tested using a well-characterized and clinically relevant ovine model of MRSA pneumonia/sepsis and in vitro assays of human lung microvascular endothelial cells (HMVECs). in vivo experiments demonstrated that the treatment of septic sheep with tolvaptan (TLVP), an FDA-approved V₂R antagonist, significantly attenuated the sepsis-induced fluid retention and markedly reduced the lung water content. These pathological changes were not affected by the treatment with V₂R agonist, desmopressin (DDAVP). Additionally, the incubation of cultured HMVECs with DDAVP, and DDAVP along with MRSA significantly increased the paracellular permeability. Finally, both the DDAVP and MRSA-induced hyperpermeability was significantly attenuated by TLVP. Subsequent protein and gene expression assays determined that the V₂R-induced increase in permeability is mediated by phospholipase C beta (PLCβ) and the potent permeability factor angiopoietin-2. In conclusion, our results indicate that the activation of the AVP-V₂R axis is critical in the pathophysiology of severe microvascular hyperpermeability during Gram-positive sepsis. The use of the antagonist TLVP should be considered as adjuvant treatment for septic patients. The results from this clinically relevant animal study are highly translational to clinical practice.

Emerging Therapeutic Modalities against COVID-19

The novel SARS-CoV-2 virus has quickly spread worldwide, bringing the whole world as well as the economy to a standstill. As the world is struggling to minimize the transmission of this devastating disease, several strategies are being actively deployed to develop therapeutic interventions. Pharmaceutical companies and academic researchers are relentlessly working to investigate experimental, repurposed or FDA-approved drugs on a compassionate basis and novel biologics for SARS-CoV-2 prophylaxis and treatment. Presently, a tremendous surge of COVID-19 clinical trials are advancing through different stages. Among currently registered clinical efforts, ~86% are centered on testing small molecules or antibodies either alone or in combination with immunomodulators. The rest ~14% of clinical efforts are aimed at evaluating vaccines and convalescent plasma-based therapies to mitigate the disease's symptoms. This review provides a comprehensive overview of current therapeutic modalities being evaluated against SARS-CoV-2 virus in clinical trials.

Systematic review of extracellular vesicle-based treatments for lung injury: are EVs a potential therapy for COVID-19?

Severe COVID-19 infection results in bilateral interstitial pneumonia, often leading to acute respiratory distress syndrome (ARDS) and pulmonary fibrosis in survivors. Most patients with severe COVID-19 infections who died had developed ARDS. Currently, ARDS is treated with supportive measures, but regenerative medicine approaches including extracellular vesicle (EV)-based therapies have shown promise. Herein, we aimed to analyse whether EV-based therapies could be effective in treating severe pulmonary conditions that affect COVID-19 patients and to understand their relevance for an eventual therapeutic application to human patients. Using a defined search strategy, we conducted a systematic review of the literature and found 39 articles (2014–2020) that reported effects of EVs, mainly derived from stem cells, in lung injury models (one large animal study, none in human). EV treatment resulted in: (1) attenuation of inflammation (reduction of pro-inflammatory cytokines and neutrophil infiltration, M2 macrophage polarization); (2) regeneration of alveolar epithelium (decreased apoptosis and stimulation of surfactant production); (3) repair of microvascular permeability (increased endothelial cell junction proteins); (4) prevention of fibrosis (reduced fibrin production). These effects were mediated by the release of EV cargo and identified factors including miRs-126, −30b-3p, −145, −27a-3p, syndecan-1, hepatocyte growth factor and angiopoietin-1. This review indicates that EV-based therapies hold great potential for COVID-19 related lung injuries as they target multiple pathways and enhance tissue regeneration. However, before translating EV therapies into human clinical trials, efforts should be directed at developing good manufacturing practice solutions for EVs and testing optimal dosage and administration route in large animal models.

Dysregulation of angiopoietin-Tie-2 axis in ugandan children hospitalized with pneumonia

OBJECTIVE

Pneumonia is the leading cause of death in children under 5, with the highest burden in resource-limited countries. Endothelial activation occurs in pneumonia and can be assessed using quantitative levels of biomarkers angiopoietin (Ang)-1 and Ang-2. We examined admission levels of Ang-1 and Ang-2 in pediatric pneumonia and their association with disease severity and outcome.

METHODS

Prospective cohort study of children with hypoxemic pneumonia admitted to two hospitals in Uganda. Clinical, radiographic, and microbiologic characteristics were measured at admission. Disease severity was assessed using the Respiratory Index of Severity in Children (RISC). Plasma levels of Ang-1 and Ang-2 were quantified by enzyme-linked immunosorbent assay. Vital signs, oxygen supplementation, and mortality were assessed prospectively.

RESULTS

We included 65 patients (43% female) with median age 19 months (IQR 8-24). Admission Ang-2/Ang-1 ratio directly correlated with RISC (ρ = 0.32, p = 0.008) and lactate level (ρ = 0.48, p < 0.001). Ang-2/Ang-1 ratio was higher in pneumococcal pneumonia than viral RTI (0.19 [IQR: 0.076-0.54] vs. 0.078 [IQR: 0.027-0.11]; p = 0.03). Elevated Ang-2/Ang-1 ratio (>0.084) was associated with prolonged tachypnea (HR 0.50 (95%CI 0.29-0.87), p = 0.02), fever (HR 0.56 (95%CI 0.33 to 0.96), p = 0.02), longer duration of oxygen therapy (HR 0.59 (95%CI 0.35-0.99), p = 0.04), and hospital stay (HR 0.43 (95%CI 0.25-0.74), p = 0.001). The Ang-2/Ang-1 ratio at admission was higher in fatal cases relative to survivors (0.36 [IQR: 0.17-0.58] vs. 0.077 [IQR: 0.025-0.19]; p = 0.05) CONCLUSION: Endothelial activation in hypoxemic pediatric pneumonia, reflected by high plasma Ang-2/Ang-1 ratio, is associated with disease severity, prolonged recovery time, and mortality.

Rationale for the clinical use of adipose-derived mesenchymal stem cells for COVID-19 patients

In late 2019, a novel coronavirus (SARS-CoV-2) emerged in Wuhan, capital city of Hubei province in China. Cases of SARS-CoV-2 infection quickly grew by several thousand per day. Less than 100 days later, the World Health Organization declared that the rapidly spreading viral outbreak had become a global pandemic. Coronavirus disease 2019 (COVID-19) is typically associated with fever and respiratory symptoms. It often progresses to severe respiratory distress and multi-organ failure which carry a high mortality rate. Older patients or those with medical comorbidities are at greater risk for severe disease. Inflammation, pulmonary edema and an over-reactive immune response can lead to hypoxia, respiratory distress and lung damage. Mesenchymal stromal/stem cells (MSCs) possess potent and broad-ranging immunomodulatory activities. Multiple in vivo studies in animal models and ex vivo human lung models have demonstrated the MSC's impressive capacity to inhibit lung damage, reduce inflammation, dampen immune responses and aid with alveolar fluid clearance. Additionally, MSCs produce molecules that are antimicrobial and reduce pain. Upon administration by the intravenous route, the cells travel directly to the lungs where the majority are sequestered, a great benefit for the treatment of pulmonary disease. The in vivo safety of local and intravenous administration of MSCs has been demonstrated in multiple human clinical trials, including studies of acute respiratory distress syndrome (ARDS). Recently, the application of MSCs in the context of ongoing COVID-19 disease and other viral respiratory illnesses has demonstrated reduced patient mortality and, in some cases, improved long-term pulmonary function. Adipose-derived stem cells (ASC), an abundant type of MSC, are proposed as a therapeutic option for the treatment of COVID-19 in order to reduce morbidity and mortality. Additionally, when proven to be safe and effective, ASC treatments may reduce the demand on critical hospital resources. The ongoing COVID-19 outbreak has resulted in significant healthcare and socioeconomic burdens across the globe. There is a desperate need for safe and effective treatments. Cellular based therapies hold great promise for the treatment of COVID-19. This literature summary reviews the scientific rationale and need for clinical studies of adipose-derived stem cells and other types of mesenchymal stem cells in the treatment of patients who suffer with COVID-19.

Sepsis therapies: learning from 30 years of failure of translational research to propose new leads

Sepsis has been identified by the World Health Organization (WHO) as a global health priority. There has been a tremendous effort to decipher underlying mechanisms responsible for organ failure and death, and to develop new treatments. Despite saving thousands of animals over the last three decades in multiple preclinical studies, no new effective drug has emerged that has clearly improved patient outcomes. In the present review, we analyze the reasons for this failure, focusing on the inclusion of inappropriate patients and the use of irrelevant animal models. We advocate against repeating the same mistakes and propose changes to the research paradigm. We discuss the long-term consequences of surviving sepsis and, finally, list some putative approaches-both old and new-that could help save lives and improve survivorship.

Biomarkers in Community-Acquired Pneumonia (Cardiac and Non-Cardiac)

Community-acquired pneumonia (CAP) remains the first cause of morbidity and mortality worldwide due to infection. Several aspects such as severity and host response are related to its clinical course and outcome. Beyond the acute implications that the infection provokes in the host, pneumonia also has long-term negative consequences. Among them, cardiovascular complications and mortality are the most outstanding. Therefore, an adequate recognition and stratification of the risk of complications and mortality is crucial. Many biomarkers have been studied for these reasons, considering that each biomarker mirrors a different aspect. Moreover, the clinical application of many of them is still being deliberated because of their limitations and the heterogeneity of the disease. In this review, we examine some of the most relevant biomarkers that we have classified as cardiac and non-cardiac. We discuss some classic biomarkers and others that are considered novel biomarkers, which are mainly involved in cardiovascular risk.

Host-Based Prognostic Biomarkers to Improve Risk Stratification and Outcome of Febrile Children in Low- and Middle-Income Countries

Fever is one of the leading causes for pediatric medical consultation and the most common symptom at clinical presentation in low- and middle-income countries (LMICs). Most febrile episodes are due to self-limited infections, but a small proportion of children will develop life-threatening infections. The early recognition of children who have or are progressing to a critical illness among all febrile cases is challenging, and there are currently no objective and quantitative tools to do so. This results in increased morbidity and mortality among children with impending life-threatening infections, whilst contributing to the unnecessary prescription of antibiotics, overwhelming health care facilities, and harm to patients receiving avoidable antimicrobial treatment. Specific fever origin is difficult to ascertain and co-infections in LMICs are common. However, many severe infections share common pathways of host injury irrespective of etiology, including immune and endothelial activation that contribute to the pathobiology of sepsis (i.e., pathogen "agnostic" mechanisms of disease). Importantly, mediators of these pathways are independent markers of disease severity and outcome. We propose that measuring circulating levels of these factors can provide quantitative and objective evidence to: enable early recognition of severe infection; guide patient triage and management; enhance post-discharge risk stratification and follow up; and mitigate potential gender bias in clinical decisions. Here, we review the clinical and biological evidence supporting the clinical utility of host immune and endothelial activation biomarkers as components of novel rapid triage tests, and discuss the challenges and needs for developing and implementing such tools.

Role of Angiopoietin-2 in Vascular Physiology and Pathophysiology

Angiopoietins 1–4 (Ang1–4) represent an important family of growth factors, whose activities are mediated through the tyrosine kinase receptors, Tie1 and Tie2. The best characterized are angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2). Ang1 is a potent angiogenic growth factor signaling through Tie2, whereas Ang2 was initially identified as a vascular disruptive agent with antagonistic activity through the same receptor. Recent data demonstrates that Ang2 has context-dependent agonist activities. Ang2 plays important roles in physiological processes and the deregulation of its expression is characteristic of several diseases. In this review, we summarize the activity of Ang2 on blood and lymphatic endothelial cells, its significance in human physiology and disease, and provide a current view of the molecular signaling pathways regulated by Ang2 in endothelial cells.

Biomarkers of Community-Acquired Pneumonia: A Key to Disease Diagnosis and Management

Community-acquired pneumonia (CAP) is a dangerous disease caused by a spectrum of bacterial and viral pathogens. The choice of specific therapy and the need for hospitalization or transfer to the intensive care unit are determined by the causative agent and disease severity. The microbiological analysis of sputum largely depends on the quality of the material obtained. The prediction of severity and the duration of therapy are determined individually, and existing prognostic scales are used generally. This review examines the possibilities of using specific serological biomarkers to detect the bacterial or viral aetiology of CAP and to assess disease severity. Particular emphasis is placed on the use of biomarker signatures and the discovery of biomarker candidates for a single multiplex analysis.

Integrating molecular pathogenesis and clinical translation in sepsis-induced acute respiratory distress syndrome

Sepsis-induced acute respiratory distress syndrome (ARDS) has high morbidity and mortality and arises after lung infection or infection at extrapulmonary sites. An aberrant host response to infection leads to disruption of the pulmonary alveolar-capillary barrier, resulting in lung injury characterized by hypoxemia, inflammation, and noncardiogenic pulmonary edema. Despite increased understanding of the molecular biology underlying sepsis-induced ARDS, there are no targeted pharmacologic therapies for this devastating condition. Here, we review the molecular underpinnings of sepsis-induced ARDS with a focus on relevant clinical and translational studies that point toward novel therapeutic strategies.