Persistent alveolar inflammatory response in critically ill patients with COVID-19 is associated with mortality

The neutrophil-to-lymphocyte ratio in bronchoalveolar lavage fluid could help to personalize corticosteroid therapy in severe COVID-19 pneumonia

OBJECTIVE

To investigate the response to high-dose corticosteroids according to bronchoalveolar neutrophil-to-lymphocyte ratio (BAL-NLR) in critically-ill COVID-19 patients.

METHODS

We retrospectively analyzed a single-center cohort of adult COVID-19 patients admitted to the intensive care unit with COVID-19 pneumonia between 2020 and 2022, who had a bronchoalveolar lavage and received systemic corticosteroids. We defined high-dose corticosteroid therapy as the administration of at least 1mg/kg/day of methylprednisolone.

RESULTS

Among 161 patients, 56 had LOWBAL-NLR (<0.8), 55 MILDBAL-NLR (0.8-3.5), and 50 HIGHBAL-NLR (>3.5). A quarter of patients received high-dose corticosteroid therapy. In the HIGHBAL-NLR group, those receiving high-dose corticosteroid therapy had a lower (27 % versus 43 %, p = 0.23) 90-day mortality rate than those receiving a standard dose. In the LOWBAL-NLR group, those receiving high-dose corticosteroid therapy had a higher (31 % versus 12 %, p = 0.12) 90-day mortality rate.

CONCLUSION

Our results suggest that bronchoalveolar cellular phenotype influences therapeutic response to high-dose corticosteroid therapy.

Integrating Pulmonary and Systemic Transcriptomic Profiles to Characterize Lung Injury after Pediatric Hematopoietic Stem Cell Transplant

Hematopoietic stem cell transplantation (HCT) is potentially curative for numerous malignant and non-malignant diseases but can lead to lung injury due to chemoradiation toxicity, infection, and immune dysregulation. Bronchoalveolar lavage (BAL) is the most commonly used procedure for diagnostic sampling of the lung but is invasive, cannot be performed in medically fragile patients, and is challenging to perform serially. We previously showed that BAL transcriptomes representing pulmonary inflammation and cellular injury can phenotype post-HCT lung injury and predict mortality outcomes. However, whether peripheral blood testing is a suitable minimally-invasive surrogate for pulmonary sampling in the HCT population remains unknown. To address this question, we compared 210 paired BAL and peripheral blood transcriptomes obtained from 166 pediatric HCT patients at 27 children's hospitals. BAL and blood mRNA abundance showed minimal overall correlation at the level of individual genes, gene set enrichment scores, imputed cell fractions, and T- and B-cell receptor clonotypes. Instead, we identified significant site-specific transcriptional programs. In BAL, expression of innate and adaptive immune pathways was tightly co-regulated with expression of epithelial mesenchymal transition and hypoxia pathways, and these signatures were associated with mortality. In contrast, in blood, expression of endothelial injury, DNA repair, and cellular metabolism pathways was associated with mortality. Integration of paired BAL and blood transcriptomes dichotomized patients into two groups, of which one group showed twice the rate of hypoxia and significantly worse outcomes within 7 days of enrollment. These findings reveal a compartmentalized injury response, where BAL and peripheral blood transcriptomes provide distinct but complementary insights into local and systemic mechanisms of post-HCT lung injury.

The Complex Immune Cell Composition and Cellular Interaction in the Alveolar Compartment of Patients with Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is characterized by protein-rich edema due to alveolar-capillary barrier dysfunction caused by inflammatory processes. Currently, our understanding of the inflammatory response in patients with ARDS is mainly based on assessment of the systemic compartment and preclinical studies. Investigations into the intricate network of immune cells and their critical functions in the alveolar compartment remain limited. However, with recent improvements in single-cell analyses, our comprehensive understanding of the interactions between immune cells in the lungs has improved. In this review, we summarize the current knowledge about the cellular composition and interactions of different immune cell types within the alveolar space of patients with ARDS. Neutrophils and macrophages are the predominant immune cells in the alveolar space of patients with ARDS. Yet, all immune cells present, including lymphocytes, participate in complex interactions, coordinate recruitment, modulate the lifespan, and control apoptosis through various signaling pathways. Moreover, the cellular composition of alveolar immune cells is associated with the clinical outcomes of patients with ARDS. In conclusion, this synthesis advances our understanding of ARDS immunology, emphasizing the crucial role of immune cells within the alveolar space. Associations between cellular composition and clinical outcomes highlight the significance of exploring distinct alveolar immune cell subsets. Such exploration holds promise for uncovering novel therapeutic targets in ARDS pathophysiology, presenting avenues for enhancing clinical management and treatment strategies for patients with ARDS.

Viral reactivations and fungal infections in nonresolving acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a condition affecting 10% of patients requiring admission to the intensive care unit and results from endothelial dysfunction, alveolar epithelial injury and unbalanced inflammation, leading to exudative pulmonary oedema. A significant portion of these patients experience a lung injury that fails to resolve. Persistent or worsening respiratory failure beyond 5 days after the initiation of mechanical ventilation is referred to as nonresolving ARDS. Viral and fungal pathogens can exploit the hyperinflammatory environment and altered immune landscape in ARDS, perpetuating a cycle of ongoing inflammation and lung injury, thereby contributing to the progression towards and persistence of nonresolving ARDS, even in previously immunocompetent patients. This review discusses the significance, pathophysiology, diagnostic challenges and key knowledge gaps concerning various viral and fungal pathogens in nonresolving ARDS, with a particular focus on influenza-associated and COVID-19-associated pulmonary aspergillosis and pulmonary reactivation of Herpesviridae, such as cytomegalovirus and herpes simplex virus. Diagnosing these infections is challenging due to their nonspecific clinical presentation and the inability of current tests to distinguish between fungal colonisation or asymptomatic viral shedding and clinically significant infections or reactivations. A deeper understanding of the complex interplay between these pathogens and the host immune system in the context of ARDS, combined with advances in diagnostic and therapeutic strategies, has the potential to enhance the management and prognosis of patients with nonresolving ARDS.

Progress of CCL20-CCR6 in the airways: a promising new therapeutic target

The chemokine CCL20, a small cytokine that belongs to the C-C chemokine family, interacts with its homologous receptor CCR6, which is expressed on wide range of cell types. According to current research, the CCL20-CCR6 has been established as acritical player in a diverse range of inflammatory, oncogenic, and autoimmune diseases. Within the respiratory system, CCL20-CCR6 demonstrates heightened expression in conditions such as allergic asthma, chronic airway inflammation, non-small cell lung cancer (NSCLC), chronic obstructive pulmonary disease (COPD), and other respiratory diseases, which is conducive to the inflammatory mediators recruitment and tumor microenvironment remodeling. Numerous studies have demonstrated that therapeutic interventions targeting CCL20 and CCR6, including antibodies and antagonists, have the potential to mitigate disease progression. Despite the promising research prospects surrounding the CCL20-CCR6 chemokine axis, the precise mechanisms underlying its action in respiratory diseases remain largely elusive. In this review, we delve into the potential roles of the CCL20-CCR6 axis within the respiratory system by synthesizing and analyzing current research findings. Our objective is to provide a comprehensive understanding of the CCL20-CCR6 axis and its implications for respiratory health and disease. And we aspire to propel research endeavors in this domain and furnish valuable insights for the development of future therapeutic strategies.

Association of blood inflammatory phenotypes and asthma burden in children with moderate-to-severe asthma

Background

Underlying immunological mechanisms in children with moderate-to-severe asthma are complex and unclear. We aimed to investigate the association between blood inflammatory parameters and asthma burden in children with moderate-to-severe asthma.

Methods

Blood inflammatory parameters (eosinophil and neutrophil counts and inflammatory mediators using multiplex immunoassay technology) were measured in children (6-17 years) with moderate-to-severe asthma from the SysPharmPediA cohort across four European countries. Based upon low/high blood eosinophil (LBE/HBE) counts of

Results

Among 126 included children (41% girls and mean (sd) age of 11.94 (2.76)), 22%, 44%, 11% and 23% were classified as mixed, eosinophilic, neutrophilic and paucigranulocytic phenotypes, respectively. Neutrophilic children had the lowest lung function (forced expiratory volume in 1 s % predicted pre-salbutamol) compared with other groups. Children with mixed asthma were most often uncontrolled and had the highest asthma-related school absence in the past year. Interleukin (IL)-6 and matrix metalloproteinase-9 levels were significantly higher in patients with mixed or neutrophilic asthma, whereas tissue inhibitor of metalloproteinase-2 was lower in patients with neutrophilic asthma compared with eosinophilic or paucigranulocytic asthma. IL-5 was increased in eosinophilic group compared with the neutrophilic and paucigranulocytic groups, irrespective of the chosen cut-off for eosinophilia.

Conclusion

Differences in asthma burden-related clinical expression and distinct blood inflammatory mediator profiles were found between phenotypes, highlighting implications for optimising personalised treatment and management strategies in children with moderate-to-severe asthma.

Collapse

Key Words Collapse

MESH Headings Collapse

Grants

• Ministry of Education, Science, and Sport of the Republic of Slovenia
• German Ministry of Education and Research
• ZonMw
• ERACoSysMed

Collapse

Affiliation(s)

Amir Hossein Alizadeh Bahmani Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Amsterdam Public Health, Personalized Medicine, Amsterdam, The Netherlands
Susanne J.H. Vijverberg Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Amsterdam Public Health, Personalized Medicine, Amsterdam, The Netherlands
Simone Hashimoto Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Department of Pediatric Pulmonology and Allergy, Emma Children's Hospital, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
Christine Wolff Department of Pediatric Pneumology and Allergy, University Children's Hospital Regensburg (KUNO), Regensburg, Germany
Catarina Almqvist Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
Lizan D. Bloemsma Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
Susanne Brandstetter KUNO, University of Regensburg, Regensburg, Germany
Paula Corcuera-Elosegui Division of Pediatric Respiratory Medicine, Hospital Universitario Donostia, San Sebastián, Spain
Mario Gorenjak Center for Human Molecular Genetics and Pharmacogenomics, Faculty of Medicine, University of Maribor, Maribor, Slovenia
Susanne Harner Department of Pediatric Pneumology and Allergy, University Children's Hospital Regensburg (KUNO), Regensburg, Germany
Anna M. Hedman Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden
Michael Kabesch Department of Pediatric Pneumology and Allergy, University Children's Hospital Regensburg (KUNO), Regensburg, Germany
Leyre López-Fernández Division of Pediatric Respiratory Medicine, Hospital Universitario Donostia, San Sebastián, Spain
Aletta D. Kraneveld Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht, The Netherlands
Anne H. Neerincx Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
Maria Pino-Yanes Genomics and Health Group, Department of Biochemistry, Microbiology, Cell Biology and Genetics, Universidad de La Laguna, Santa Cruz de Tenerife, Spain CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain Instituto de Tecnologías Biomédicas, Universidad de La Laguna, La Laguna, Spain
Uroš Potočnik Center for Human Molecular Genetics and Pharmacogenomics, Faculty of Medicine, University of Maribor, Maribor, Slovenia
Olaia Sardón-Prado Division of Pediatric Respiratory Medicine, Hospital Universitario Donostia, San Sebastián, Spain Department of Pediatrics, School of Medicine and Nursery, University of the Basque Country, San Sebastián, Spain
Barbara S. Dierdorp Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Department of Experimental Immunology, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
Tamara Dekker Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Department of Experimental Immunology, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
Nariman K.A. Metwally Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
Jan Willem Duitman Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Department of Experimental Immunology, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
René Lutter Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Department of Experimental Immunology, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands
Paul Brinkman Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Amsterdam Public Health, Personalized Medicine, Amsterdam, The Netherlands
Mahmoud I. Abdel-Aziz Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Amsterdam Public Health, Personalized Medicine, Amsterdam, The Netherlands
Anke H. Maitland-van der Zee Department of Pulmonary Medicine, Amsterdam UMC Location University of Amsterdam, Amsterdam, The Netherlands Amsterdam Institute for Infection and Immunity, Inflammatory Diseases, Amsterdam, The Netherlands Amsterdam Public Health, Personalized Medicine, Amsterdam, The Netherlands

Collapse

PD-L1 and PD-1 Are Associated with Clinical Outcomes and Alveolar Immune Cell Activation in Acute Respiratory Distress Syndrome

The relationship between the PD-L1 (Programmed Death-Ligand 1)/PD-1 pathway, lung inflammation, and clinical outcomes in acute respiratory distress syndrome (ARDS) is poorly understood. We sought to determine whether PD-L1/PD-1 in the lung or blood is associated with ARDS and associated severity. We measured soluble PD-L1 (sPD-L1) in plasma and lower respiratory tract samples (ARDS1 [n = 59] and ARDS2 [n = 78]) or plasma samples alone (ARDS3 [n = 149]) collected from subjects with ARDS and tested for associations with mortality using multiple regression. We used mass cytometry to measure PD-L1/PD-1 expression and intracellular cytokine staining in cells isolated from BAL fluid (n = 18) and blood (n = 16) from critically ill subjects with or without ARDS enrolled from a fourth cohort. Higher plasma concentrations of sPD-L1 were associated with mortality in ARDS1, ARDS2, and ARDS3. In contrast, higher concentrations of sPD-L1 in the lung were either not associated with mortality (ARDS2) or were associated with survival (ARDS1). Alveolar PD-1POS T cells had more intracellular cytokine staining than PD-1NEG T cells. Subjects without ARDS had a higher ratio of PD-L1POS alveolar macrophages to PD-1POS T cells than subjects with ARDS. We conclude that sPD-L1 may have divergent cellular sources and/or functions in the alveolar versus blood compartments, given distinct associations with mortality. Alveolar leukocyte subsets defined by PD-L1 or PD-1 cell-surface expression have distinct cytokine secretion profiles, and the relative proportions of these subsets are associated with ARDS.

Acute respiratory distress syndrome

The understanding of acute respiratory distress syndrome (ARDS) has evolved greatly since it was first described in a 1967 case series, with several subsequent updates to the definition of the syndrome. Basic science advances and clinical trials have provided insight into the mechanisms of lung injury in ARDS and led to reduced mortality through comprehensive critical care interventions. This review summarizes the current understanding of the epidemiology, pathophysiology, and management of ARDS. Key highlights include a recommended new global definition of ARDS and updated guidelines for managing ARDS on a backbone of established interventions such as low tidal volume ventilation, prone positioning, and a conservative fluid strategy. Future priorities for investigation of ARDS are also highlighted.

Heterogeneity, Bayesian thinking, and phenotyping in critical care: A primer

PURPOSE

To familiarize clinicians with the emerging concepts in critical care research of Bayesian thinking and personalized medicine through phenotyping and explain their clinical relevance by highlighting how they address the issues of frequent negative trials and heterogeneity of treatment effect.

SUMMARY

The past decades have seen many negative (effect-neutral) critical care trials of promising interventions, culminating in calls to improve the field's research through adopting Bayesian thinking and increasing personalization of critical care medicine through phenotyping. Bayesian analyses add interpretive power for clinicians as they summarize treatment effects based on probabilities of benefit or harm, contrasting with conventional frequentist statistics that either affirm or reject a null hypothesis. Critical care trials are beginning to include prospective Bayesian analyses, and many trials have undergone reanalysis with Bayesian methods. Phenotyping seeks to identify treatable traits to target interventions to patients expected to derive benefit. Phenotyping and subphenotyping have gained prominence in the most syndromic and heterogenous critical care disease states, acute respiratory distress syndrome and sepsis. Grouping of patients has been informative across a spectrum of clinically observable physiological parameters, biomarkers, and genomic data. Bayesian thinking and phenotyping are emerging as elements of adaptive clinical trials and predictive enrichment, paving the way for a new era of high-quality evidence. These concepts share a common goal, sifting through the noise of heterogeneity in critical care to increase the value of existing and future research.

CONCLUSION

The future of critical care medicine will inevitably involve modification of statistical methods through Bayesian analyses and targeted therapeutics via phenotyping. Clinicians must be familiar with these systems that support recommendations to improve decision-making in the gray areas of critical care practice.

Pulmonary herpes simplex virus and cytomegalovirus in patients with acute respiratory distress syndrome related to COVID-19

PURPOSE

Human herpesviruses, particularly cytomegalovirus (CMV) and herpes simplex virus (HSV), frequently reactivate in critically ill patients, including those with acute respiratory distress syndrome (ARDS) related to coronavirus disease 2019 (COVID-19). The clinical interpretation of pulmonary herpesvirus reactivation is challenging and there is ongoing debate about its association with mortality and benefit of antiviral medication. We aimed to quantify the incidence and pathogenicity of pulmonary CMV and HSV reactivations in critically ill COVID-19 patients.

METHODS

Mechanically ventilated COVID-19 patients seropositive for CMV or HSV were included in this observational cohort study. Diagnostic bronchoscopy with bronchoalveolar lavage was performed routinely and analyzed for alveolar viral loads and inflammatory biomarkers. Utilizing joint modeling, we explored the dynamic association between viral load trajectories over time and mortality. We explored alveolar inflammatory biomarker dynamics between reactivated and non-reactivated patients.

RESULTS

Pulmonary reactivation (> 104 copies/ml) of CMV occurred in 6% of CMV-seropositive patients (9/156), and pulmonary reactivation of HSV in 37% of HSV-seropositive patients (63/172). HSV viral load dynamics prior to or without antiviral treatment were associated with increased 90-day mortality (hazard ratio [HR] 1.24, 95% confidence interval [CI] 1.04-1.47). The alveolar concentration of several inflammatory biomarkers increased with HSV reactivation, including interleukin (IL)-6, IL-1β, granulocyte colony stimulating factor (G-CSF), and tumor necrosis factor (TNF).

CONCLUSION

In mechanically ventilated COVID-19 patients, HSV reactivations are common, while CMV reactivations were rare. HSV viral load dynamics prior to or without antiviral treatment are associated with mortality. Alveolar inflammation is elevated after HSV reactivation.

Higher levels of IL-1ra, IL-6, IL-8, MCP-1, MIP-3α, MIP-3β, and fractalkine are associated with 90-day mortality in 132 non-immunomodulated hospitalized patients with COVID-19

INTRODUCTION

Immune dysregulation with an excessive release of cytokines has been identified as a key driver in the development of severe COVID-19. The aim of this study was to evaluate the initial cytokine profile associated with 90-day mortality and respiratory failure in a cohort of patients hospitalized with COVID 19 that did not receive immunomodulatory therapy.

METHODS

Levels of 45 cytokines were measured in blood samples obtained at admission from patients with confirmed COVID-19. Logistic regression analysis was utilized to determine the association between cytokine levels and outcomes. The primary outcome was death within 90 days from admission and the secondary outcome was need for mechanical ventilation.

RESULTS

A total of 132 patients were included during the spring of 2020. We found that one anti-inflammatory cytokine, one pro-inflammatory cytokine, and five chemokines were associated with the odds of 90-day mortality, specifically: interleukin-1 receptor antagonist, interleukin-6, interleukin-8, monocyte chemoattractant protein-1, macrophage inflammatory protein-3α, macrophage inflammatory protein-3β, and fractalkine. All but fractalkine were also associated with the odds of respiratory failure during admission. Monocyte chemoattractant protein-1 showed the strongest estimate of association with both outcomes.

CONCLUSION

We showed that one anti-inflammatory cytokine, one pro-inflammatory cytokine, and five chemokines were associated with 90-day mortality in patients hospitalized with COVID-19 that did not receive immunomodulatory therapy.

A narrative review of chemokine receptors CXCR1 and CXCR2 and their role in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a severe form of acute respiratory failure characterised by extensive inflammatory injury to the alveolocapillary barrier leading to alveolar oedema, impaired gas exchange and, ultimately, hypoxaemia necessitating the use of supplemental oxygen combined with some degree of positive airway pressure. Although much heterogeneity exists regarding the aetiology, localisation and endotypic characterisation of ARDS, what remains largely undisputed is the role of the innate immune system, and in particular of neutrophils, in precipitating and propagating lung injury. Activated neutrophils, recruited to the lung through chemokine gradients, promote injury by releasing oxidants, proteases and neutrophil extracellular traps, which ultimately cause platelet aggregation, microvascular thrombosis and cellular death. Among various neutrophilic chemoattractants, interleukin-8/C-X-C motif ligand 8 and related chemokines, collectively called ELR+ chemokines, acting on neutrophils through the G protein-coupled receptors CXCR1 and CXCR2, are pivotal in orchestrating the neutrophil activation status and chemotaxis in the inflamed lung. This allows efficient elimination of infectious agents while at the same time minimising collateral damage to host tissue. Therefore, understanding how CXCR1 and CXCR2 receptors are regulated is important if we hope to effectively target them for therapeutic use in ARDS. In the following narrative review, we provide an overview of the role of ELR+ chemokines in acute lung injury (ALI) and ARDS, we summarise the relevant regulatory pathways of their cognisant receptors CXCR1/2 and highlight current preclinical and clinical evidence on the therapeutic role of CXCR1 and CXCR2 inhibition in animal models of ALI, as well as in ARDS patients.

Longitudinal multicompartment characterization of host-microbiota interactions in patients with acute respiratory failure

Critical illness can significantly alter the composition and function of the human microbiome, but few studies have examined these changes over time. Here, we conduct a comprehensive analysis of the oral, lung, and gut microbiota in 479 mechanically ventilated patients (223 females, 256 males) with acute respiratory failure. We use advanced DNA sequencing technologies, including Illumina amplicon sequencing (utilizing 16S and ITS rRNA genes for bacteria and fungi, respectively, in all sample types) and Nanopore metagenomics for lung microbiota. Our results reveal a progressive dysbiosis in all three body compartments, characterized by a reduction in microbial diversity, a decrease in beneficial anaerobes, and an increase in pathogens. We find that clinical factors, such as chronic obstructive pulmonary disease, immunosuppression, and antibiotic exposure, are associated with specific patterns of dysbiosis. Interestingly, unsupervised clustering of lung microbiota diversity and composition by 16S independently predicted survival and performed better than traditional clinical and host-response predictors. These observations are validated in two separate cohorts of COVID-19 patients, highlighting the potential of lung microbiota as valuable prognostic biomarkers in critical care. Understanding these microbiome changes during critical illness points to new opportunities for microbiota-targeted precision medicine interventions.

Biological effects of corticosteroids on pneumococcal pneumonia in Mice-translational significance

BACKGROUND

Streptococcus pneumoniae is the most common bacterial cause of community acquired pneumonia and the acute respiratory distress syndrome (ARDS). Some clinical trials have demonstrated a beneficial effect of corticosteroid therapy in community acquired pneumonia, COVID-19, and ARDS, but the mechanisms of this benefit remain unclear. The primary objective of this study was to investigate the effects of corticosteroids on the pulmonary biology of pneumococcal pneumonia in a mouse model. A secondary objective was to identify shared transcriptomic features of pneumococcal pneumonia and steroid treatment in the mouse model and clinical samples.

METHODS

We carried out comprehensive physiologic, biochemical, and histological analyses in mice to identify the mechanisms of lung injury in Streptococcus pneumoniae with and without adjunctive steroid therapy. We also studied lower respiratory tract gene expression from a cohort of 15 mechanically ventilated patients (10 with Streptococcus pneumoniae and 5 controls) to compare with the transcriptional studies in the mice.

RESULTS

In mice with pneumonia, dexamethasone in combination with ceftriaxone reduced (1) pulmonary edema formation, (2) alveolar protein permeability, (3) proinflammatory cytokine release, (4) histopathologic lung injury score, and (5) hypoxemia but did not increase bacterial burden. Transcriptomic analyses identified effects of steroid therapy in mice that were also observed in the clinical samples.

CONCLUSIONS

In combination with appropriate antibiotic therapy in mice, treatment of pneumococcal pneumonia with steroid therapy reduced hypoxemia, pulmonary edema, lung permeability, and histologic criteria of lung injury, and also altered inflammatory responses at the protein and gene expression level. The transcriptional studies in patients suggest that the mouse model replicates some of the features of pneumonia in patients with Streptococcus pneumoniae and steroid treatment. Overall, these studies provide evidence for the mechanisms that may explain the beneficial effects of glucocorticoid therapy in patients with community acquired pneumonia from Streptococcus Pneumoniae.

Case study observational research: inflammatory cytokines in the bronchial epithelial lining fluid of COVID-19 patients with acute hypoxemic respiratory failure

BACKGROUND

In this study, the concentrations of inflammatory cytokines were measured in the bronchial epithelial lining fluid (ELF) and plasma in patients with acute hypoxemic respiratory failure (AHRF) secondary to severe coronavirus disease 2019 (COVID-19).

METHODS

We comprehensively analyzed the concentrations of 25 cytokines in the ELF and plasma of 27 COVID-19 AHRF patients. ELF was collected using the bronchial microsampling method through an endotracheal tube just after patients were intubated for mechanical ventilation.

RESULTS

Compared with those in healthy volunteers, the concentrations of interleukin (IL)-6 (median 27.6 pmol/L), IL-8 (1045.1 pmol/L), IL-17A (0.8 pmol/L), IL-25 (1.5 pmol/L), and IL-31 (42.3 pmol/L) were significantly greater in the ELF of COVID-19 patients than in that of volunteers. The concentrations of MCP-1 and MIP-1β were significantly greater in the plasma of COVID-19 patients than in that of volunteers. The ELF/plasma ratio of IL-8 was the highest among the 25 cytokines, with a median of 737, and the ELF/plasma ratio of IL-6 (median: 218), IL-1β (202), IL-31 (169), MCP-1 (81), MIP-1β (55), and TNF-α (47) were lower.

CONCLUSIONS

The ELF concentrations of IL-6, IL-8, IL-17A, IL-25, and IL-31 were significantly increased in COVID-19 patients. Although high levels of MIP-1 and MIP-1β were also detected in the blood samples collected simultaneously with the ELF samples, the results indicated that lung inflammation was highly compartmentalized. Our study demonstrated that a comprehensive analysis of cytokines in the ELF is a feasible approach for understanding lung inflammation and systemic interactions in patients with severe pneumonia.

Potential therapeutic targets for COVID-19 complicated with pulmonary hypertension: a bioinformatics and early validation study

Coronavirus disease (COVID-19) and pulmonary hypertension (PH) are closely correlated. However, the mechanism is still poorly understood. In this article, we analyzed the molecular action network driving the emergence of this event. Two datasets (GSE113439 and GSE147507) from the GEO database were used for the identification of differentially expressed genes (DEGs).Common DEGs were selected by VennDiagram and their enrichment in biological pathways was analyzed. Candidate gene biomarkers were selected using three different machine-learning algorithms (SVM-RFE, LASSO, RF).The diagnostic efficacy of these foundational genes was validated using independent datasets. Eventually, we validated molecular docking and medication prediction. We found 62 common DEGs, including several ones that could be enriched for Immune Response and Inflammation. Two DEGs (SELE and CCL20) could be identified by machine-learning algorithms. They performed well in diagnostic tests on independent datasets. In particular, we observed an upregulation of functions associated with the adaptive immune response, the leukocyte-lymphocyte-driven immunological response, and the proinflammatory response. Moreover, by ssGSEA, natural killer T cells, activated dendritic cells, activated CD4 T cells, neutrophils, and plasmacytoid dendritic cells were correlated with COVID-19 and PH, with SELE and CCL20 showing the strongest correlation with dendritic cells. Potential therapeutic compounds like FENRETI-NIDE, AFLATOXIN B1 and 1-nitropyrene were predicted. Further molecular docking and molecular dynamics simulations showed that 1-nitropyrene had the most stable binding with SELE and CCL20.The findings indicated that SELE and CCL20 were identified as novel diagnostic biomarkers for COVID-19 complicated with PH, and the target of these two key genes, FENRETI-NIDE and 1-nitropyrene, was predicted to be a potential therapeutic target, thus providing new insights into the prediction and treatment of COVID-19 complicated with PH in clinical practice.

Reframing sepsis immunobiology for translation: towards informative subtyping and targeted immunomodulatory therapies

Sepsis is a common and deadly condition. Within the current model of sepsis immunobiology, the framing of dysregulated host immune responses into proinflammatory and immunosuppressive responses for the testing of novel treatments has not resulted in successful immunomodulatory therapies. Thus, the recent focus has been to parse observable heterogeneity into subtypes of sepsis to enable personalised immunomodulation. In this Personal View, we highlight that many fundamental immunological concepts such as resistance, disease tolerance, resilience, resolution, and repair are not incorporated into the current sepsis immunobiology model. The focus for addressing heterogeneity in sepsis should be broadened beyond subtyping to encompass the identification of deterministic molecular networks or dominant mechanisms. We explicitly reframe the dysregulated host immune responses in sepsis as altered homoeostasis with pathological disruption of immune-driven resistance, disease tolerance, resilience, and resolution mechanisms. Our proposal highlights opportunities to identify novel treatment targets and could enable successful immunomodulation in the future.

Longitudinal plasma proteomics reveals biomarkers of alveolar-capillary barrier disruption in critically ill COVID-19 patients

The pathobiology of respiratory failure in COVID-19 consists of a complex interplay between viral cytopathic effects and a dysregulated host immune response. In critically ill patients, imatinib treatment demonstrated potential for reducing invasive ventilation duration and mortality. Here, we perform longitudinal profiling of 6385 plasma proteins in 318 hospitalised patients to investigate the biological processes involved in critical COVID-19, and assess the effects of imatinib treatment. Nine proteins measured at hospital admission accurately predict critical illness development. Next to dysregulation of inflammation, critical illness is characterised by pathways involving cellular adhesion, extracellular matrix turnover and tissue remodelling. Imatinib treatment attenuates protein perturbations associated with inflammation and extracellular matrix turnover. These proteomic alterations are contextualised using external pulmonary RNA-sequencing data of deceased COVID-19 patients and imatinib-treated Syrian hamsters. Together, we show that alveolar capillary barrier disruption in critical COVID-19 is reflected in the plasma proteome, and is attenuated with imatinib treatment. This study comprises a secondary analysis of both clinical data and plasma samples derived from a clinical trial that was registered with the EU Clinical Trials Register (EudraCT 2020-001236-10, https://www.clinicaltrialsregister.eu/ctr-search/trial/2020-001236-10/NL ) and Netherlands Trial Register (NL8491, https://www.trialregister.nl/trial/8491 ).

The alveolar fibroproliferative response in moderate to severe COVID-19-related acute respiratory distress syndrome and 1-yr follow-up

COVID-19-related acute respiratory distress syndrome (ARDS) can lead to long-term pulmonary fibrotic lesions. Alveolar fibroproliferative response (FPR) is a key factor in the development of pulmonary fibrosis. N-terminal peptide of procollagen III (NT-PCP-III) is a validated biomarker for activated FPR in ARDS. This study aimed to assess the association between dynamic changes in alveolar FPR and long-term outcomes, as well as mortality in COVID-19 ARDS patients. We conducted a prospective cohort study of 154 COVID-19 ARDS patients. We collected bronchoalveolar lavage (BAL) and blood samples for measurement of 17 pulmonary fibrosis biomarkers, including NT-PCP-III. We assessed pulmonary function and chest computed tomography (CT) at 3 and 12 mo after hospital discharge. We performed joint modeling to assess the association between longitudinal changes in biomarker levels and mortality at day 90 after starting mechanical ventilation. 154 patients with 284 BAL samples were analyzed. Of all patients, 40% survived to day 90, of whom 54 completed the follow-up procedure. A longitudinal increase in NT-PCP-III was associated with increased mortality (HR 2.89, 95% CI: 2.55-3.28; P < 0.001). Forced vital capacity and diffusion for carbon monoxide were impaired at 3 mo but improved significantly at one year after hospital discharge (P = 0.03 and P = 0.004, respectively). There was no strong evidence linking alveolar FPR during hospitalization and signs of pulmonary fibrosis in pulmonary function or chest CT images during 1-yr follow-up. In COVID-19 ARDS patients, alveolar FPR during hospitalization was associated with higher mortality but not with the presence of long-term fibrotic lung sequelae within survivors.NEW & NOTEWORTHY This is the first prospective study on the longitudinal alveolar fibroproliferative response in COVID-19 ARDS and its relationship with mortality and long-term follow-up. We used the largest cohort of COVID-19 ARDS patients who had consecutive bronchoalveolar lavages and measured 17 pulmonary fibroproliferative biomarkers. We found that a higher fibroproliferative response during admission was associated with increased mortality, but not correlated with long-term fibrotic lung sequelae in survivors.