Pulmonary infections complicating ARDS

Naringin dihydrochalcone alleviates sepsis-induced acute lung injury via improving gut microbial homeostasis and activating GPR18 receptor

Acute lung injury (ALI) is a life-threatening disease characterized by severe lung inflammation and intestinal microbiota disorder. The GPR18 receptor has been demonstrated to be a potential therapeutic target against ALI. Extracting Naringin dihydrochalcone (NDC) from the life-sustaining orange peel is known for its diverse anti-inflammatory properties, yet the specific action target remains uncertain. In the present study, we identified NDC as a potential agonist of the GPR18 receptor using virtual screening and investigated the pharmacological effects of NDC on sepsis-induced acute lung injury in rats and explored underlying mechanisms. In in vivo experiments, CLP-induced ALI model was established by cecum puncture and treated with NDC gavage one hour prior to drug administration, lung histopathology and inflammatory cytokines were evaluated, and feces were subjected to 16s rRNA sequencing and untargeted metabolomics analysis. In in vitro experiments, the anti-inflammatory properties were exerted by evaluating NDC targeting the GPR18 receptor to inhibit lipopolysaccharide (LPS)-induced secretion of TNF-α, IL-6, IL-1β and activation of inflammatory signaling pathways in MH-S cells. Our findings showed that NDC significantly ameliorated lung damage and pro-inflammatory cytokine levels (TNF-α, IL-6, IL-1β) in both cells and lung tissues via inhibiting the activation of STAT3, NF-κB, and NLRP3 inflammatory signaling pathways through GRP18 receptor activation. In addition, NDC can also partly reverse the imbalance of gut microbiota composition caused by CLP via increasing the proportion of Firmicutes/Bacteroidetes and Lactobacillus and decreasing the relative abundance of Proteobacteria. Meanwhile, the fecal metabolites in the NDC treatment group also significantly were changed, including decreased secretion of Phenylalanin, Glycine, and bile secretion, and increased secretion of Lysine. In conclusion, these findings suggest that NDC can alleviate sepsis-induced ALI via improving gut microbial homeostasis and metabolism and mitigate inflammation via activating GPR18 receptor. In conclusion, the results indicate that NDC, derived from the typical orange peel of food, could significantly contribute to development by enhancing intestinal microbial balance and metabolic processes, and reducing inflammation by activating the GPR18 receptor, thus mitigating sepsis-induced ALI and expanding the range of functional foods.

Tetrastigma hemsleyanum polysaccharide ameliorates cytokine storm syndrome via the IFN-γ-JAK2/STAT pathway

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is an disease characterized by pulmonary edema and widespread inflammation, leading to a notably high mortality rate. The dysregulation of both pro-inflammatory and anti-inflammatory systems, results in cytokine storm (CS), is intricately associated with the development of ALI/ARDS. Tetrastigma hemsleyanum polysaccharide (THP) exerts remarkable anti-inflammatory and immunomodulatory effects against the disease, although its precise role in pathogenesis remains unclear. In the present study, an ALI/ARDS model was established using bacterial lipopolysaccharides. THP administration via aerosol inhalation significantly mitigated lung injury, reduced the number of inflammatory cells, and ameliorated glycerophospholipid metabolism. Furthermore, specific CS-related pathways were investigated by examining the synergy between tumor necrosis factor-α and interferon-γ used to establish CS models. The results indicated that THP effectively decreased inflammatory damage and cell death. The RNA sequencing revealed the involvement of the Janus kinase (JAK) 2-signal transducers and activators of transcription (STAT) signaling pathway in exerting the mentioned effects. Additionally, THP inhibited the activation of the JAK-STAT pathway, thereby alleviating the CS both in vivo and in vitro. Overall, THP exhibited marked therapeutic potential against ALI/ARDS and CS, primarily by targeting the IFN-γ-JAK2/STAT signaling pathway.

Emerging liver infection of Veillonella parvula associated with acute respiratory distress syndrome: a case report

Introduction

Veillonella parvula is a bacteria that can be found in normal oral and gastrointestinal flora. Veillonella infection is rare in immunocompetent patients but is known to cause periorbital cellulitis, endocarditis, osteomyelitis and bacteremia; however, its association with acute respiratory distress syndrome (ARDS) has not been previously documented.

Case presentation

A 36-year-old female with no known history who presented with right-sided chest, flank and upper abdominal pain after a motor vehicle accident. Computed tomography showed multiple right rib fractures, small right pneumothorax, and a grade 4 liver laceration with active extravasation of the posterior aspect of the right liver lobe. Over the hospital course, the patient developed ARDS and was intubated for hypoxemia. A right posterior liver abscess was percutaneously drained, with a copious amount of air and ~30 ml turbid fluid aspirated. Cultures from the liver abscess grew Veillonella parvula. She was treated with Micafungin, Levofloxacin, and Metronidazole for the hepatic abscess, and was discharged home with outpatient follow-up.

Discussion

The authors present one of the first reported cases of a V. parvula infected liver abscess associated with ARDS in an immunocompetent patient.

Conclusion

These clinical findings are unique due to the nature of our patient's ARDS onset and the dearth of similar cases in the literature. The favorable outcome of our patient was due to a multidisciplinary and early identification of a V. parvula hepatic abscess. The authors' findings contribute to the future management of V. parvula and a greater understanding of its disseminating effects and presentation in immunocompetent patients.

Using the sympathetic system, beta blockers and alpha-2 agonists, to address acute respiratory distress syndrome

Acute Respiratory Distress Syndrome (ARDS) manifests as an acute inflammatory lung injury characterized by persistent hypoxemia, featuring a swift onset, high mortality, and predominantly supportive care as the current therapeutic approach, while effective treatments remain an area of active investigation. Adrenergic receptors (AR) play a pivotal role as stress hormone receptors, extensively participating in various inflammatory processes by initiating downstream signaling pathways. Advancements in molecular biology and pharmacology continually unveil the physiological significance of distinct AR subtypes. Interventions targeting these subtypes have the potential to induce specific alterations in cellular and organismal functions, presenting a promising avenue as a therapeutic target for managing ARDS. This article elucidates the pathogenesis of ARDS and the basic structure and function of AR. It also explores the relationship between AR and ARDS from the perspective of different AR subtypes, aiming to provide new insights for the improvement of ARDS.

IL-10 Counteracts IFN-γ to Alleviate Acute Lung Injury in a Viral-Bacterial Superinfection Model

Immune activation is essential for lung control of viral and bacterial infection, but an overwhelming inflammatory response often leads to the onset of acute respiratory distress syndrome. IL-10 plays a crucial role in regulating the balance between antimicrobial immunity and immunopathology. In the present study, we investigated the role of IL-10 in acute lung injury induced by influenza A virus and methicillin-resistant Staphylococcus aureus coinfection. This unique coinfection model resembles patients with acute pneumonia undergoing appropriate antibiotic therapies. Using global IL-10 and IL-10 receptor gene-deficient mice, as well as in vivo neutralizing antibodies, we show that IL-10 deficiency promotes IFN-γ-dominant cytokine responses and triggers acute animal death. Interestingly, this extreme susceptibility is fully preventable by IFN-γ neutralization during coinfection. Further studies using mice with Il10ra deletion in selective myeloid subsets reveal that IL-10 primarily acts on mononuclear phagocytes to prevent IFN-γ/TNF-α hyperproduction and acute mortality. Importantly, this antiinflammatory IL-10 signaling is independent of its inhibitory effect on antiviral and antibacterial defense. Collectively, our results demonstrate a key mechanism of IL-10 in preventing hypercytokinemia and acute respiratory distress syndrome pathogenesis by counteracting the IFN-γ response.

Ultrasound-Mediated Antibiotic Delivery to In Vivo Biofilm Infections: A Review

Bacterial biofilms are a significant concern in various medical contexts due to their resilience to our immune system as well as antibiotic therapy. Biofilms often require surgical removal and frequently lead to recurrent or chronic infections. Therefore, there is an urgent need for improved strategies to treat biofilm infections. Ultrasound-mediated drug delivery is a technique that combines ultrasound application, often with the administration of acoustically-active agents, to enhance drug delivery to specific target tissues or cells within the body. This method involves using ultrasound waves to assist in the transportation or activation of medications, improving their penetration, distribution, and efficacy at the desired site. The advantages of ultrasound-mediated drug delivery include targeted and localized delivery, reduced systemic side effects, and improved efficacy of the drug at lower doses. This review scrutinizes recent advances in the application of ultrasound-mediated drug delivery for treating biofilm infections, focusing on in vivo studies. We examine the strengths and limitations of this technology in the context of wound infections, device-associated infections, lung infections and abscesses, and discuss current gaps in knowledge and clinical translation considerations.

Outpatient insulin use in type 2 diabetes mellitus and acute respiratory distress syndrome outcomes: A retrospective cohort study

BACKGROUND

The impact of type 2 diabetes mellitus (T2DM) on acute respiratory distress syndrome (ARDS) is debatable. T2DM was suspected to reduce the risk and complications of ARDS. However, during coronavirus disease 2019 (COVID-19), T2DM predisposed patients to ARDS, especially those who were on insulin at home.

AIM

To evaluate the impact of outpatient insulin use in T2DM patients on non-COVID-19 ARDS outcomes.

METHODS

We conducted a retrospective cohort analysis using the Nationwide Inpatient Sample database. Adult patients diagnosed with ARDS were stratified into insulin-dependent diabetes mellitus (DM) (IDDM) and non-insulin-dependent DM (NIDDM) groups. After applying exclusion criteria and matching over 20 variables, we compared cohorts for mortality, duration of mechanical ventilation, incidence of acute kidney injury (AKI), length of stay (LOS), hospitalization costs, and other clinical outcomes.

RESULTS

Following 1:1 propensity score matching, the analysis included 274 patients in each group. Notably, no statistically significant differences emerged between the IDDM and NIDDM groups in terms of mortality rates (32.8% vs 31.0%, P = 0.520), median hospital LOS (10 d, P = 0.537), requirement for mechanical ventilation, incidence rates of sepsis, pneumonia or AKI, median total hospitalization costs, or patient disposition upon discharge.

CONCLUSION

Compared to alternative anti-diabetic medications, outpatient insulin treatment does not appear to exert an independent influence on in-hospital morbidity or mortality in diabetic patients with non-COVID-19 ARDS.

A nomogram predicting pneumonia after cardiac surgery: a retrospective modeling study

BACKGROUND

Postoperative pneumonia (POP) is the most prevalent of all nosocomial infections in patients who underwent cardiac surgery. The aim of this study was to identify independent risk factors for pneumonia after cardiac surgery, from which we constructed a nomogram for prediction.

METHODS

The clinical data of patients admitted to the Department of Cardiothoracic Surgery of Nanjing Drum Tower Hospital from October 2020 to September 2021 who underwent cardiac surgery were retrospectively analyzed, and the patients were divided into two groups according to whether they had POP: POP group (n=105) and non-POP group (n=1083). Preoperative, intraoperative, and postoperative indicators were collected and analyzed. Logistic regression was used to identify independent risk factors for POP in patients who underwent cardiac surgery. We constructed a nomogram based on these independent risk factors. Model discrimination was assessed via area under the receiver operating characteristic curve (AUC), and calibration was assessed via calibration plot.

RESULTS

A total of 105 events occurred in the 1188 cases. Age (>55 years) (OR: 1.83, P=0.0225), preoperative malnutrition (OR: 3.71, P<0.0001), diabetes mellitus(OR: 2.33, P=0.0036), CPB time (Cardiopulmonary Bypass Time) > 135 min (OR: 2.80, P<0.0001), moderate to severe ARDS (Acute Respiratory Distress Syndrome )(OR: 1.79, P=0.0148), use of ECMO or IABP or CRRT (ECMO: Extra Corporeal Membrane Oxygenation; IABP: Intra-Aortic Balloon Pump; CRRT: Continuous Renal Replacement Therapy )(OR: 2.60, P=0.0057) and MV( Mechanical Ventilation )> 20 hours (OR: 3.11, P<0.0001) were independent risk factors for POP. Based on those independent risk factors, we constructed a simple nomogram with an AUC of 0.82. Calibration plots showed good agreement between predicted probabilities and actual probabilities.

CONCLUSION

We constructed a facile nomogram for predicting pneumonia after cardiac surgery with good discrimination and calibration. The model has excellent clinical applicability and can be used to identify and adjust modifiable risk factors to reduce the incidence of POP as well as patient mortality.

Establishment and validation of a predictive model for tracheotomy in critically ill patients and analysis of the impact of different tracheotomy timing on patient prognosis

BACKGROUND

In critically ill patients receiving invasive mechanical ventilation (IMV), it is unable to determine early which patients require tracheotomy and whether early tracheotomy is beneficial.

METHODS

Clinical data of patients who were first admitted to the ICU and underwent invasive ventilation for more than 24 h in the Medical Information Marketplace in Intensive Care (MIMIC)-IV database were retrospectively collected. Patients were categorized into successful extubation and tracheotomy groups according to whether they were subsequently successfully extubated or underwent tracheotomy. The patients were randomly divided into model training set and validation set in a ratio of 7:3. Constructing predictive models and evaluating and validating the models. The tracheotomized patients were divided into the early tracheotomy group (< = 7 days) and the late tracheotomy group (> 7 days), and the prognosis of the two groups was analyzed.

RESULTS

A total of 7 key variables were screened: Glasgow coma scale (GCS) score, pneumonia, traumatic intracerebral hemorrhage, hemorrhagic stroke, left and right pupil responses to light, and parenteral nutrition. The area under the receiver operator characteristic (ROC) curve of the prediction model constructed through these seven variables was 0.897 (95% CI: 0.876-0.919), and 0.896 (95% CI: 0.866-0.926) for the training and validation sets, respectively. Patients in the early tracheotomy group had a shorter length of hospital stay, IMV duration, and sedation duration compared to the late tracheotomy group (p < 0.05), but there was no statistically significant difference in survival outcomes between the two groups.

CONCLUSION

The prediction model constructed and validated based on the MIMIC-IV database can accurately predict the outcome of tracheotomy in critically ill patients. Meanwhile, early tracheotomy in critically ill patients does not improve survival outcomes but has potential advantages in shortening the duration of hospitalization, IMV, and sedation.

Establishment of a Predictive Model for Acute Respiratory Distress Syndrome in Patients with Bacterial Pneumonia

Background

Community-acquired pneumonia (CAP) is a global health concern due to its high rates of morbidity and mortality. Bacterial pathogens are common causes of CAP. It is one of the most common causes of acute respiratory distress syndrome (ARDS), a common severe respiratory system manifestation threatening human health. This study aimed to establish a predictive model for ARDS in patients with bacterial pneumonia, which was conducive to early identification of the occurrence and effective prevention of ARDS.

Methods

We collected the clinical data of hospitalized patients with bacterial pneumonia in Affiliated Huzhou Hospital of Zhejiang University School of Medicine from January 2022 to November 2022. The independent risk factors for ARDS in patients with bacterial pneumonia were determined by univariate and multivariate binary logistic regression analyses. The nomogram was constructed to display the predictive model, and the receiver-operating characteristic curve was plotted to evaluate the predictive value of ARDS.

Results

This study included 254 patients with bacterial pneumonia, of which 114 developed ARDS. The multivariate logistic regression analysis revealed age [odds ratio (OR) = 1.041, P = 0.003], heart rate (OR = 1.020, P = 0.028), lymphocyte count (OR = 0.555, P = 0.033), white blood cell count (OR = 1.062, P = 0.033), bilateral lung lesions (OR = 7.352, P = 0.011) and pleural effusion (OR = 2.512, P = 0.002) as the independent risk factors for ARDS. The predictive model was constructed based on the six independent factors, which was valuable in predicting ARDS with area under the curve of 0.794.

Conclusion

The predictive model was beneficial to evaluate the disease progression in patients with bacterial pneumonia and identify ARDS. Further, our nomogram might help doctors predict the incidence of ARDS and conduct treatment as early as possible.

Artificial intelligence for the optimal management of community-acquired pneumonia

PURPOSE OF REVIEW

This timely review explores the integration of artificial intelligence (AI) into community-acquired pneumonia (CAP) management, emphasizing its relevance in predicting the risk of hospitalization. With CAP remaining a global public health concern, the review highlights the need for efficient and reliable AI tools to optimize resource allocation and improve patient outcomes.

RECENT FINDINGS

Challenges in CAP management delve into the application of AI in predicting CAP-related hospitalization risks, and complications, and mortality. The integration of AI-based risk scores in managing CAP has the potential to enhance the accuracy of predicting patients at higher risk, facilitating timely intervention and resource allocation. Moreover, AI algorithms reduce variability associated with subjective clinical judgment, promoting consistency in decision-making, and provide real-time risk assessments, aiding in the dynamic management of patients with CAP.

SUMMARY

The development and implementation of AI-tools for hospitalization in CAP represent a transformative approach to improving patient outcomes. The integration of AI into healthcare has the potential to revolutionize the way we identify and manage individuals at risk of severe outcomes, ultimately leading to more efficient resource utilization and better overall patient care.

Antimicrobial Drug Penetration Is Enhanced by Lung Tissue Inflammation and Injury

Rationale: Pneumonia is a frequent and feared complication in intubated critically ill patients. Tissue concentrations of antimicrobial drugs need to be sufficiently high to treat the infection and also prevent development of bacterial resistance. It is uncertain whether pulmonary inflammation and injury affect antimicrobial drug penetration into lung tissue.Objectives: To determine and compare tissue and BAL fluid concentrations of ceftaroline fosamil and linezolid in a model of unilateral acute lung injury in pigs and to evaluate whether dose adjustment is necessary to reach sufficient antimicrobial concentrations in injured lung tissue.Methods: After induction of unilateral acute lung injury, ceftaroline fosamil and linezolid were administered intravenously. Drug concentrations were measured in lung tissue through microdialysis and in blood and BAL fluid samples during the following 8 hours. The primary endpoint was the tissue concentration area under the concentration curve in the first 8 hours (AUC0-8 h) of the two antimicrobial drugs.Measurements and Main Results: In 10 pigs, antimicrobial drug concentrations were higher in inflamed and injured lung tissue compared with those in uninflamed and uninjured lung tissue (median ceftaroline fosamil AUC0-8 h [and interquartile range] = 26.7 mg ⋅ h ⋅ L-1 [19.7-39.0] vs. 16.0 mg ⋅ h ⋅ L-1 [13.6-19.9], P = 0.02; median linezolid AUC0-8 h 76.0 mg ⋅ h ⋅ L-1 [68.1-96.0] vs. 54.6 mg ⋅ h ⋅ L-1 [42.7-60.9], P = 0.01), resulting in a longer time above the minimal inhibitory concentration and in higher peak concentrations and dialysate/plasma ratios. Penetration into BAL fluid was excellent for both antimicrobials, but without left-to-right differences (ceftaroline fosamil, P = 0.78; linezolid, P = 1.00).Conclusions: Tissue penetration of two commonly used antimicrobial drugs for pneumonia is enhanced by early lung tissue inflammation and injury, resulting in longer times above the minimal inhibitory concentration. Thus, lung tissue inflammation ameliorates antimicrobial drug penetration during the acute phase.

Th17/Treg balance: the bloom and wane in the pathophysiology of sepsis

Sepsis is a multi-organ dysfunction characterized by an unregulated host response to infection. It is associated with high morbidity, rapid disease progression, and high mortality. Current therapies mainly focus on symptomatic treatment, such as blood volume supplementation and antibiotic use, but their effectiveness is limited. Th17/Treg balance, based on its inflammatory property, plays a crucial role in determining the direction of the inflammatory response and the regression of organ damage in sepsis patients. This review provides a summary of the changes in T-helper (Th) 17 cell and regulatory T (Treg) cell differentiation and function during sepsis, the heterogeneity of Th17/Treg balance in the inflammatory response, and the relationship between Th17/Treg balance and organ damage. Th17/Treg balance exerts significant control over the bloom and wanes in host inflammatory response throughout sepsis.

Inhibition of sphingosine kinase 1 attenuates LPS-induced acute lung injury by suppressing endothelial cell pyroptosis

Acute lung injury (ALI) is a frequent complication of sepsis, with pyroptosis playing a pivotal role. Analysis of Gene Expression Omnibus (GEO) mouse sepsis datasets revealed the upregulation of sphingosine kinase 1 (SphK1) in septic mouse lung tissues, which was validated in lipopolysaccharide (LPS)-treated mice. Therefore, this study aimed to explore the potential role and underlying mechanisms of SphK1, the primary kinase responsible for catalyzing the formation of the bioactive lipid sphingosine-1-phosphat, in sepsis development. Mice received an intraperitoneal injection of SphK1 inhibitor prior to LPS administration. Mouse lung vascular endothelial cells (MLVECs) were exposed to LPS and SphK1 inhibitor. The SphK1 inhibitor mitigated ALI, as evidenced by hematoxylin and eosin (H&E) staining and the wet-to-dry (W/D) weight ratio and reduced Evans blue dye leakage. Furthermore, the SphK1 inhibitor inhibited the activation of the NOD-like receptor protein 3 inflammasome and the subsequent induction of pyroptosis both in vivo and in vitro. Intriguingly, using co-immunoprecipitation (Co-IP) combined with mass spectrometry, our findings revealed that SphK1 associates with pyruvate kinase M2 (PKM2), facilitating PKM2 phosphorylation and its nuclear translocation. TEPP-46, which has the ability to stabilize PKM2 and inhibit the phosphorylation and nuclear translocation of PKM2, markedly reduced the expression of pyroptosis-associated markers and alleviated lung injury. Concludingly, our results suggest that targeting SphK1 is a promising therapeutic strategy for ALI.

Tau and Aβ42 in lavage fluid of pneumonia patients are associated with end-organ dysfunction: A prospective exploratory study

BACKGROUND

Bacterial pneumonia and sepsis are both common causes of end-organ dysfunction, especially in immunocompromised and critically ill patients. Pre-clinical data demonstrate that bacterial pneumonia and sepsis elicit the production of cytotoxic tau and amyloids from pulmonary endothelial cells, which cause lung and brain injury in naïve animal subjects, independent of the primary infection. The contribution of infection-elicited cytotoxic tau and amyloids to end-organ dysfunction has not been examined in the clinical setting. We hypothesized that cytotoxic tau and amyloids are present in the bronchoalveolar lavage fluid of critically ill patients with bacterial pneumonia and that these tau/amyloids are associated with end-organ dysfunction.

METHODS

Bacterial culture-positive and culture-negative mechanically ventilated patients were recruited into a prospective, exploratory observational study. Levels of tau and Aβ42 in, and cytotoxicity of, the bronchoalveolar lavage fluid were measured. Cytotoxic tau and amyloid concentrations were examined in comparison with patient clinical characteristics, including measures of end-organ dysfunction.

RESULTS

Tau and Aβ42 were increased in culture-positive patients (n = 49) compared to culture-negative patients (n = 50), independent of the causative bacterial organism. The mean age of patients was 52.1 ± 16.72 years old in the culture-positive group and 52.78 ± 18.18 years old in the culture-negative group. Males comprised 65.3% of the culture-positive group and 56% of the culture-negative group. Caucasian culture-positive patients had increased tau, boiled tau, and Aβ42 compared to both Caucasian and minority culture-negative patients. The increase in cytotoxins was most evident in males of all ages, and their presence was associated with end-organ dysfunction.

CONCLUSIONS

Bacterial infection promotes the generation of cytotoxic tau and Aβ42 within the lung, and these cytotoxins contribute to end-organ dysfunction among critically ill patients. This work illuminates an unappreciated mechanism of injury in critical illness.

Effect of COVID-19 on infections associated with medical devices in critical care

OBJECTIVES

This study explores the hypothesis that COVID-19 patients are at a heightened risk of healthcare-associated infections (HAIs) associated with medical device usage compared to non-COVID-19 patients. Our primary objective was to investigate the correlation between COVID-19 infection in ICU patients and subsequent HAIs following invasive medical device insertion. Additionally, we aim to assess the impact of SARS-CoV-2 infection on onset times concerning specific microorganisms and the type of medical device, providing valuable insights into this intricate relationship in intensive care settings.

METHODOLOGY

A retrospective cohort study was conducted using ICU patient records at our hospital from 2020 to 2022. This investigation entailed evaluating the timing of HAIs while distinguishing between patients with and without SARS-CoV-2 infection. We identified and analyzed the type of isolation and infection attributed to the medical device while controlling for ICU duration and ventilator days using Cox regression.

RESULTS

Our study included 127 patients without SARS-CoV-2 infection and 140 patients with SARS-CoV-2 infection. The findings indicated a higher incidence of HAI caused by various microorganisms associated with any medical device in patients with SARS-CoV-2 (HR = 6.86; 95% CI-95%: 3.26-14.43; p < 0.01). After adjusting for ICU duration and ventilator days, a heightened frequency of HAIs persisted in SARS-CoV-2-infected individuals. However, a detailed examination of HAIs revealed that only ventilation-associated pneumonia (VAP) displayed a significant association (HR = 6.69; 95% CI: 2.59-17.31; p < 0.01). A statistically significant correlation between SARS-CoV-2 infection and the isolation of S. aureus was also observed (p = 0.034). The prevalence of S. aureus infection was notably higher in patients with SARS-CoV-2 (RR = 8.080; 95% CI: 1.052-62.068; p < 0.01).

CONCLUSIONS

The frequency of pathogen isolates in invasive medical devices exhibited an association with SARS-CoV-2 infection. Critically ill patients with SARS-CoV-2 are more prone to developing early-onset VAP than those without SARS-CoV-2 infection.

Associations of Awake Prone Positioning-Induced Changes in Physiology with Intubation: An International Prospective Observational Study in Patients with Acute Hypoxemic Respiratory Failure Related to COVID-19

INTRODUCTION

Awake prone positioning has the potential to improve oxygenation and decrease respiratory rate, potentially reducing the need for intubation in patients with acute hypoxemic respiratory failure. We investigated awake prone positioning-induced changes in oxygenation and respiratory rate, and the prognostic capacity for intubation in patients with COVID-19 pneumonia.

METHODS

International multicenter prospective observation study in critically ill adult patients with COVID-19 receiving supplemental oxygen. We collected data on oxygenation and respiratory rate at baseline, and at 1 h after being placed in prone positioning. The combined primary outcome was oxygenation and respiratory rate at 1 h. The secondary endpoint was treatment failure, defined as need for intubation within 24 h of start of awake prone positioning.

RESULTS

Between March 27th and November 2020, 101 patients were enrolled of which 99 were fully analyzable. Awake prone positioning lasted mean of 3 [2-4] h. In 77 patients (77.7%), awake prone positioning improved oxygenation, and in 37 patients (54.4%) it decreased respiratory rate. Twenty-nine patients (29.3%) were intubated within 24 h. An increase in SpO2/FiO2 of < 10 (OR 5.1, 95% CI 1.4-18.5, P = 0.01), a failure to increase PaO2/FiO2 to > 116 mmHg (OR 3.6, 95% CI 1.2-10.8, P = 0.02), and a decrease in respiratory rate of < 2 breaths/min (OR 3.6, 95% CI 1.3-9.5, P = 0.01) were independent variables associated with need for intubation. The AUC-ROC curve for intubation using a multivariable model was 0.73 (95% CI 0.62-0.84).

CONCLUSIONS

Awake prone positioning improves oxygenation in the majority of patients, and decreases respiratory rate in more than half of patients with acute hypoxemic respiratory failure caused by COVID-19. One in three patients need intubation within 24 h. Awake prone position-induced changes in oxygenation and respiratory rate have prognostic capacity for intubation within 24 h.

α 2 -ADRENORECEPTOR ANTAGONIST AMELIORATES SEPSIS-ASSOCIATED PULMONARY FIBROSIS BY SUPPRESSING NOREPINEPHRINE-MEDIATED FIBROBLAST DIFFERENTIATION VIA INHIBITING PKC ACTIVATION

ABSTRACT

Pulmonary fibrosis is an important factor affecting the prognosis of severe septic patients with acute lung injury. The objective of this study was to explore the effect of norepinephrine (NE) and α 2 -adrenoreceptor (AR) on sepsis-associated pulmonary fibrosis and the mechanism underlying these effects. We found pulmonary fibrotic changes, and increased NE production and α 2A -AR expression in the pulmonary tissue of mice subjected to cecal ligation and puncture surgery. Reserpine and yohimbine alleviated pulmonary fibrosis in mice with sepsis by exhausting NE derived from the lung's adrenergic nerve and blocking α 2 -AR, respectively. There was no significant difference in the expression of the three α 1 -AR subtypes. The effect of NE on promoting pulmonary fibroblast differentiation in vitro was suppressed by yohimbine. Both the protein and mRNA expression levels of α 2A -AR were increased in pulmonary fibroblasts treated with LPS. Clonidine, a selective α 2 -AR agonist, enhanced LPS-induced differentiation in pulmonary fibroblasts, as indicated by the increase in α-smooth muscle actin and collagen I/III, which was mitigated by inhibiting PKC and p38. Further in vivo results indicated that yohimbine alleviated pulmonary fibrosis and inhibited the phosphorylation of PKC, p38, and Smad2/3 in lung tissue of mice exposed to LPS for 4 weeks. Clonidine showed the opposite effect to yohimbine, which aggravated LPS-induced pulmonary fibrosis. These findings demonstrated that the sepsis-induced increase in NE promoted fibroblast differentiation via activating α 2 -AR. Blockage of α 2 -AR effectively ameliorated sepsis-associated pulmonary fibrosis by abolishing NE-induced lung fibroblast differentiation and inhibiting the PKC-p38-Smad2/3 pathway.

A prediction model for acute respiratory distress syndrome in immunocompetent adults with adenovirus-associated Pneumonia: a multicenter retrospective analysis

BACKGROUND

In recent years, the number of human adenovirus (HAdV)-related pneumonia cases has increased in immunocompetent adults. Acute respiratory distress syndrome (ARDS) in these patients is the predominant cause of HADV-associated fatality rates. This study aimed to identify early risk factors to predict early HAdV-related ARDS.

METHODS

Data from immunocompetent adults with HAdV pneumonia between June 2018 and May 2022 in ten tertiary general hospitals in central China was analyzed retrospectively. Patients were categorized into the ARDS group based on the Berlin definition. The prediction model of HAdV-related ARDS was developed using multivariate stepwise logistic regression and visualized using a nomogram.

RESULTS

Of 102 patients with adenovirus pneumonia, 41 (40.2%) developed ARDS. Overall, most patients were male (94.1%), the median age was 38.0 years. Multivariate logistic regression showed that dyspnea, SOFA (Sequential Organ Failure Assessment) score, lactate dehydrogenase (LDH) and mechanical ventilation status were independent risk factors for this development, which has a high mortality rate (41.5%). Incorporating these factors, we established a nomogram with good concordance statistics of 0.904 (95% CI 0.844-0.963) which may help to predict early HAdV-related ARDS.

CONCLUSION

A nomogram with good accuracy in the early prediction of ARDS in patients with HAdV-associated pneumonia may could contribute to the early management and effective treatment of severe HAdV infection.

Robust airway microbiome signatures in acute respiratory failure and hospital-acquired pneumonia

Respiratory microbial dysbiosis is associated with acute respiratory distress syndrome (ARDS) and hospital-acquired pneumonia (HAP) in critically ill patients. However, we lack reproducible respiratory microbiome signatures that can increase our understanding of these conditions and potential treatments. Here, we analyze 16S rRNA sequencing data from 2,177 respiratory samples collected from 1,029 critically ill patients (21.7% with ARDS and 26.3% with HAP) and 327 healthy controls, sourced from 17 published studies. After data harmonization and pooling of individual patient data, we identified microbiota signatures associated with ARDS, HAP and prolonged mechanical ventilation. Microbiota signatures for HAP and prolonged mechanical ventilation were characterized by depletion of a core group of microbes typical of healthy respiratory samples, and the ARDS microbiota signature was distinguished by enrichment of potentially pathogenic respiratory microbes, including Pseudomonas and Staphylococcus. Using machine learning models, we identified clinically informative, three- and four-factor signatures that predicted ARDS, HAP and prolonged mechanical ventilation with relatively high accuracy (area under the curve of 0.751, 0.72 and 0.727, respectively). We validated the signatures in an independent prospective cohort of 136 patients on mechanical ventillation and found that patients with microbiome signatures associated with ARDS, HAP or prolonged mechanical ventilation had longer times to successful extubation than patients lacking these signatures (hazard ratios of 1.56 (95% confidence interval (CI) 1.07-2.27), 1.51 (95% CI 1.02-2.23) and 1.50 (95% CI 1.03-2.18), respectively). Thus, we defined and validated robust respiratory microbiome signatures associated with ARDS and HAP that may help to identify promising targets for microbiome therapeutic modulation in critically ill patients.

Healthcare-associated infections in critical COVID-19 patients in Tunis: epidemiology, risk factors, and outcomes

BACKGROUND

Coronavirus disease 2019 (COVID-19) pandemic disrupted adherences to healthcare-associated infection (HAI) prevention protocols. Herein, we studied the characteristics of all HAIs occurring in critically ill COVID-19 patients.

METHODS

A retrospective, single-center cohort of critical COVID-19 patients during 2021. Microbiological samples were collected if HAI was suspected. We analyzed all factors that could potentially induce HAI, using septic shock and mortality as endpoints.

RESULTS

Sixty-four among 161 included patients (39.7%) presented a total of 117 HAIs with an incidence density of 69.2 per 1,000 hospitalization days. Compared to the prior COVID-19 period (2013-2019), the identification of HAI increased in 2021. HAIs were classified into ventilator-associated pneumonia (VAP; n=38), bloodstream infection (n=32), urinary tract infection (n=24), catheter-related infection (n=12), and fungal infection (n=11). All HAIs occurred significantly earlier in the post-COVID-19 period (VAP: 6 vs. 10 days, P=0.045, in 2017 and 2021). Acinetobacter baumannii (39.5%) and Klebsiella pneumoniae (27%) were the most commonly isolated pathogens that exhibited a multidrug-resistant (MDR) profile, observed in 89% and 64.5%, respectively. The HAI factors were laboratory abnormalities (odds ratio [OR], 6.4; 95% confidence interval [CI], 2.3-26.0), cumulative steroid dose (OR, 1.9; 95% CI, 1.3-4.0), and invasive procedures (OR, 20.7; 95% CI, 5.3-64.0). HAI was an independent factor of mortality (OR, 8.5; P=0.004).

CONCLUSIONS

During the COVID-19 era, the incidence of HAIs increased and MDR isolates remained frequent. A severe biological inflammatory syndrome, invasive devices, and elevated cumulative steroid dosages were related to HAIs. HAI was a significant death factor.

Mortality, incidence, and microbiological documentation of ventilated acquired pneumonia (VAP) in critically ill patients with COVID-19 or influenza

BACKGROUND

Data on ventilator associated pneumonia (VAP) in COVID-19 and influenza patients admitted to intensive care units (ICU) are scarce. This study aimed to estimate day-60 mortality related to VAP in ICU patients ventilated for at least 48 h, either for COVID-19 or for influenza, and to describe the epidemiological characteristics in each group of VAP.

DESIGN

Multicentre retrospective observational study.

SETTING

Eleven ICUs of the French OutcomeRea™ network.

PATIENTS

Patients treated with invasive mechanical ventilation (IMV) for at least 48 h for either COVID-19 or for flu.

RESULTS

Of the 585 patients included, 503 had COVID-19 and 82 had influenza between January 2008 and June 2021. A total of 232 patients, 209 (41.6%) with COVID-19 and 23 (28%) with influenza, developed 375 VAP episodes. Among the COVID-19 and flu patients, VAP incidences for the first VAP episode were, respectively, 99.2 and 56.4 per 1000 IMV days (p < 0.01), and incidences for all VAP episodes were 32.8 and 17.8 per 1000 IMV days (p < 0.01). Microorganisms of VAP were Gram-positive cocci in 29.6% and 23.5% of episodes of VAP (p < 0.01), respectively, including Staphylococcus aureus in 19.9% and 11.8% (p = 0.25), and Gram-negative bacilli in 84.2% and 79.4% (p = 0.47). In the overall cohort, VAP was associated with an increased risk of day-60 mortality (aHR = 1.77 [1.36; 2.30], p < 0.01), and COVID-19 had a higher mortality risk than influenza (aHR = 2.22 [CI 95%, 1.34; 3.66], p < 0.01). VAP was associated with increased day-60 mortality among COVID-19 patients (aHR = 1.75 [CI 95%, 1.32; 2.33], p < 0.01), but not among influenza patients (aHR = 1.75 [CI 95%, 0.48; 6.33], p = 0.35).

CONCLUSION

The incidence of VAP was higher in patients ventilated for at least 48 h for COVID-19 than for influenza. In both groups, Gram-negative bacilli were the most frequently detected microorganisms. In patients ventilated for either COVID-19 or influenza VAP and COVID-19 were associated with a higher risk of mortality.

Efficiency of exogenous surfactant combined with intravenous N-acetylcysteine in two-hit rodent model of ARDS

Accumulation of reactive oxygen species during hyperoxia together with secondary bacteria-induced inflammation leads to lung damage in ventilated critically ill patients. Antioxidant N-acetylcysteine (NAC) in combination with surfactant may improve lung function. We compared the efficacy of NAC combined with surfactant in the double-hit model of lung injury. Bacterial lipopolysaccharide (LPS) instilled intratracheally and hyperoxia were used to induce lung injury in Wistar rats. Animals were mechanically ventilated and treated intravenously with NAC alone or in combination with intratracheal surfactant (poractant alfa; PSUR+NAC). Control received saline. Lung functions, inflammatory markers, oxidative damage, total white blood cell (WBC) count and lung oedema were evaluated during 4 hrs. Administration of NAC increased total antioxidant capacity (TAC) and decreased IL-6. This effect was potentiated by the combined administration of surfactant and NAC. In addition, PSUR+NAC reduced the levels of TNFα, IL-1ß, and TAC compared to NAC only and improved lung injury score. The combination of exogenous surfactant with NAC suppresses lung inflammation and oxidative stress in the experimental double-hit model of lung injury.

Systemic cytokines inhibition with Imp7 siRNA nanoparticle ameliorates gut injury in a mouse model of ventilator-induced lung injury

Mechanical ventilation (MV) may negatively affect the lungs and cause the release of inflammatory mediators, resulting in extra-pulmonary organ dysfunction. Studies have revealed systemically elevated levels of proinflammatory cytokines in animal models of ventilator-induced lung injury (VILI); however, whether these cytokines have an effect on gut injury and the mechanisms involved remain unknown. In this study, VILI was generated in mice with high tidal volume mechanical ventilation (20 ml/kg). Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6 concentrations in serum and gut measured by ELISA showed significant elevation in the VILI mice. Significant increases in gut injury and PANoptosis were observed in the VILI mice, which were positively correlated with the serum levels of TNF-α, IL-1β, and IL-6. The VILI mice displayed intestinal barrier defects, decreased expressions of occludin and zonula occludin-1 (ZO-1), and increased expression of claudin-2 and the activation of myosin light chain (MLC). Importantly, intratracheal administration of Imp7 siRNA nanoparticle effectively inhibited cytokines production and protected mice from VILI-induced gut injury. These data provide evidence of systemic cytokines contributing to gut injury following VILI and highlight the possibility of targeting cytokines inhibition via Imp7 siRNA nanoparticle as a potential therapeutic intervention for alleviating gut injury following VILI.

Pulmonary inflammation and fibroblast immunoregulation: from bench to bedside

In recent years, there has been an explosion of interest in how fibroblasts initiate, sustain, and resolve inflammation across disease states. Fibroblasts contain heterogeneous subsets with diverse functionality. The phenotypes of these populations vary depending on their spatial distribution within the tissue and the immunopathologic cues contributing to disease progression. In addition to their roles in structurally supporting organs and remodeling tissue, fibroblasts mediate critical interactions with diverse immune cells. These interactions have important implications for defining mechanisms of disease and identifying potential therapeutic targets. Fibroblasts in the respiratory tract, in particular, determine the severity and outcome of numerous acute and chronic lung diseases, including asthma, chronic obstructive pulmonary disease, acute respiratory distress syndrome, and idiopathic pulmonary fibrosis. Here, we review recent studies defining the spatiotemporal identity of the lung-derived fibroblasts and the mechanisms by which these subsets regulate immune responses to insult exposures and highlight past, current, and future therapeutic targets with relevance to fibroblast biology in the context of acute and chronic human respiratory diseases. This perspective highlights the importance of tissue context in defining fibroblast-immune crosstalk and paves the way for identifying therapeutic approaches to benefit patients with acute and chronic pulmonary disorders.

The role of macrophages polarization in sepsis-induced acute lung injury

Sepsis presents as a severe infectious disease frequently documented in clinical settings. Characterized by its systemic inflammatory response syndrome, sepsis has the potential to trigger multi-organ dysfunction and can escalate to becoming life-threatening. A common fallout from sepsis is acute lung injury (ALI), which often progresses to acute respiratory distress syndrome (ARDS). Macrophages, due to their significant role in the immune system, are receiving increased attention in clinical studies. Macrophage polarization is a process that hinges on an intricate regulatory network influenced by a myriad of signaling molecules, transcription factors, epigenetic modifications, and metabolic reprogramming. In this review, our primary focus is on the classically activated macrophages (M1-like) and alternatively activated macrophages (M2-like) as the two paramount phenotypes instrumental in sepsis' host immune response. An imbalance between M1-like and M2-like macrophages can precipitate the onset and exacerbate the progression of sepsis. This review provides a comprehensive understanding of the interplay between macrophage polarization and sepsis-induced acute lung injury (SALI) and elaborates on the intervention strategy that centers around the crucial process of macrophage polarization.

Klebsiella pneumoniae C o-infection Leads to Fatal Pneumonia in SARS-CoV-2-infected Mice

SARS-CoV-2 patients have been reported to have high rates of secondary Klebsiella pneumoniae infections. Klebsiella pneumoniae is a commensal that is typically found in the respiratory and gastrointestinal tracts. However, it can cause severe disease when a person's immune system is compromised. Despite a high number of K. pneumoniae cases reported in SARS-CoV-2 patients, a co-infection animal model evaluating the pathogenesis is not available. We describe a mouse model to study disease pathogenesis of SARS-CoV-2 and K. pneumoniae co-infection. BALB/cJ mice were inoculated with mouse-adapted SARS-CoV-2 followed by a challenge with K. pneumoniae . Mice were monitored for body weight change, clinical signs, and survival during infection. The bacterial load, viral titers, immune cell accumulation and phenotype, and histopathology were evaluated in the lungs. The co-infected mice showed severe clinical disease and a higher mortality rate within 48 h of K. pneumoniae infection. The co-infected mice had significantly elevated bacterial load in the lungs, however, viral loads were similar between co-infected and single-infected mice. Histopathology of co-infected mice showed severe bronchointerstitial pneumonia with copious intralesional bacteria. Flow cytometry analysis showed significantly higher numbers of neutrophils and macrophages in the lungs. Collectively, our results demonstrated that co-infection of SARS-CoV-2 with K. pneumoniae causes severe disease with increased mortality in mice.

Ventilator-associated events: From surveillance to optimizing management

Mechanical ventilation (MV) is a life-support therapy that may predispose to morbid and lethal complications, with ventilator-associated pneumonia (VAP) being the most prevalent. In 2013, the Center for Disease Control (CDC) defined criteria for ventilator-associated events (VAE). Ten years later, a growing number of studies assessing or validating its clinical applicability and the potential benefits of its inclusion have been published. Surveillance with VAE criteria is retrospective and the focus is often on a subset of patients with higher than lower severity. To date, it is estimated that around 30% of ventilated patients in the intensive care unit (ICU) develop VAE. While surveillance enhances the detection of infectious and non-infectious MV-related complications that are severe enough to impact the patient's outcomes, there are still many gaps in its classification and management. In this review, we provide an update by discussing VAE etiologies, epidemiology, and classification. Preventive strategies on optimizing ventilation, sedative and neuromuscular blockade therapy, and restrictive fluid management are warranted. An ideal VAE bundle is likely to minimize the period of intubation. We believe that it is time to progress from just surveillance to clinical care. Therefore, with this review, we have aimed to provide a roadmap for future research on the subject.

Personalized Respiratory Support in ARDS: A Physiology-to-Bedside Review

Acute respiratory distress syndrome (ARDS) is a leading cause of disability and mortality worldwide, and while no specific etiologic interventions have been shown to improve outcomes, noninvasive and invasive respiratory support strategies are life-saving interventions that allow time for lung recovery. However, the inappropriate management of these strategies, which neglects the unique features of respiratory, lung, and chest wall mechanics may result in disease progression, such as patient self-inflicted lung injury during spontaneous breathing or by ventilator-induced lung injury during invasive mechanical ventilation. ARDS characteristics are highly heterogeneous; therefore, a physiology-based approach is strongly advocated to titrate the delivery and management of respiratory support strategies to match patient characteristics and needs to limit ARDS progression. Several tools have been implemented in clinical practice to aid the clinician in identifying the ARDS sub-phenotypes based on physiological peculiarities (inspiratory effort, respiratory mechanics, and recruitability), thus allowing for the appropriate application of personalized supportive care. In this narrative review, we provide an overview of noninvasive and invasive respiratory support strategies, as well as discuss how identifying ARDS sub-phenotypes in daily practice can help clinicians to deliver personalized respiratory support and potentially improve patient outcomes.

Assessment of Inspiratory Effort in Spontaneously Breathing COVID-19 ARDS Patients Undergoing Helmet CPAP: A Comparison between Esophageal, Transdiaphragmatic and Central Venous Pressure Swing

INTRODUCTION

The clinical features of COVID-19 are highly variable. It has been speculated that the progression across COVID-19 may be triggered by excessive inspiratory drive activation. The aim of the present study was to assess whether the tidal swing in central venous pressure (ΔCVP) is a reliable estimate of inspiratory effort.

METHODS

Thirty critically ill patients with COVID-19 ARDS underwent a PEEP trial (0-5-10 cmH₂O) during helmet CPAP. Esophageal (ΔPes) and transdiaphragmatic (ΔPdi) pressure swings were measured as indices of inspiratory effort. ΔCVP was assessed via a standard venous catheter. A low and a high inspiratory effort were defined as ΔPes ≤ 10 and  >15 cmH2O, respectively.

RESULTS

During the PEEP trial, no significant changes in ΔPes (11 [6-16] vs. 11 [7-15] vs. 12 [8-16] cmH2O, p = 0.652) and in ΔCVP (12 [7-17] vs. 11.5 [7-16] vs. 11.5 [8-15] cmH2O, p = 0.918) were detected. ΔCVP was significantly associated with ΔPes (marginal R² 0.87, p < 0.001). ΔCVP recognized both low (AUC-ROC curve 0.89 [0.84-0.96]) and high inspiratory efforts (AUC-ROC curve 0.98 [0.96-1]).

CONCLUSIONS

ΔCVP is an easily available a reliable surrogate of ΔPes and can detect a low or a high inspiratory effort. This study provides a useful bedside tool to monitor the inspiratory effort of spontaneously breathing COVID-19 patients.

Biopharmaceutical Assessment of Mesh Aerosolised Plasminogen, a Step towards ARDS Treatment

Acute respiratory distress syndrome (ARDS) is a severe complication of lung injuries, commonly associated with bacterial, fungal and viral infections, including SARS-CoV-2 viral infections. ARDS is strongly correlated with patient mortality and its clinical management is very complex, with no effective treatment presently available. ARDS involves severe respiratory failure, fibrin deposition in both airways and lung parenchyma, with the development of an obstructing hyaline membrane drastically limiting gas exchange. Moreover, hypercoagulation is related to deep lung inflammation, and a pharmacological action toward both aspects is expected to be beneficial. Plasminogen (PLG) is a main component of the fibrinolytic system playing key roles in various inflammation regulatory processes. The inhalation of PLG has been proposed in the form of the off-label administration of an eyedrop solution, namely, a plasminogen-based orphan medicinal product (PLG-OMP), by means of jet nebulisation. Being a protein, PLG is susceptible to partial inactivation under jet nebulisation. The aim of the present work is to demonstrate the efficacy of the mesh nebulisation of PLG-OMP in an in vitro simulation of clinical off-label administration, considering both the enzymatic and immunomodulating activities of PLG. Biopharmaceutical aspects are also investigated to corroborate the feasibility of PLG-OMP administration by inhalation. The nebulisation of the solution was performed using an Aerogen^® Solo^TM vibrating-mesh nebuliser. Aerosolised PLG showed an optimal in vitro deposition profile, with 90% of the active ingredient impacting the lower portions of a glass impinger. The nebulised PLG remained in its monomeric form, with no alteration of glycoform composition and 94% of enzymatic activity maintenance. Activity loss was observed only when PLG-OMP nebulisation was performed under simulated clinical oxygen administration. In vitro investigations evidenced good penetration of aerosolised PLG through artificial airway mucus, as well as poor permeation across an Air-Liquid Interface model of pulmonary epithelium. The results suggest a good safety profile of inhalable PLG, excluding high systemic absorption but with good mucus diffusion. Most importantly, the aerosolised PLG was capable of reversing the effects of an LPS-activated macrophage RAW 264.7 cell line, demonstrating the immunomodulating activity of PLG in an already induced inflammatory state. All physical, biochemical and biopharmaceutical assessments of mesh aerosolised PLG-OMP provided evidence for its potential off-label administration as a treatment for ARDS patients.

Increased Alveolar Epithelial Damage Markers and Inflammasome-Regulated Cytokines Are Associated with Pulmonary Superinfection in ARDS

Acute respiratory distress syndrome (ARDS) is a life-threatening form of respiratory failure defined by dysregulated immune homeostasis and alveolar epithelial and endothelial damage. Up to 40% of ARDS patients develop pulmonary superinfections, contributing to poor prognosis and increasing mortality. Understanding what renders ARDS patients highly susceptible to pulmonary superinfections is therefore essential. We hypothesized that ARDS patients who develop pulmonary superinfections display a distinct pulmonary injury and pro-inflammatory response pattern. Serum and BALF samples from 52 patients were collected simultaneously within 24 h of ARDS onset. The incidence of pulmonary superinfections was determined retrospectively, and the patients were classified accordingly. Serum concentrations of the epithelial markers soluble receptor for advanced glycation end-products (sRAGE) and surfactant protein D (SP-D) and the endothelial markers vascular endothelial growth factor (VEGF) and angiopoetin-2 (Ang-2) as well as bronchoalveolar lavage fluid concentrations of the pro-inflammatory cytokines interleukin 1ß (IL-1ß), interleukin 18 (IL-18), interleukin 6 (IL-6), and tumor necrosis factor-alpha (TNF-a) were analyzed via multiplex immunoassay. Inflammasome-regulated cytokine IL-18 and the epithelial damage markers SP-D and sRAGE were significantly increased in ARDS patients who developed pulmonary superinfections. In contrast, endothelial markers and inflammasome-independent cytokines did not differ between the groups. The current findings reveal a distinct biomarker pattern that indicates inflammasome activation and alveolar epithelial injury. This pattern may potentially be used in future studies to identify high-risk patients, enabling targeted preventive strategies and personalized treatment approaches.

Acute Respiratory Distress Syndrome; A Review of Recent Updates and a Glance into the Future

Acute respiratory distress syndrome (ARDS) is a rapidly progressive form of respiratory failure that accounts for 10% of admissions to the ICU and is associated with approximately 40% mortality in severe cases. Despite significant mortality and healthcare burden, the mainstay of management remains supportive care. The recent pandemic of SARS-CoV-2 has re-ignited a worldwide interest in exploring the pathophysiology of ARDS, looking for innovative ideas to treat this disease. Recently, many trials have been published utilizing different pharmacotherapy targets; however, the long-term benefits of these agents remain unknown. Metabolomics profiling and stem cell transplantation offer strong enthusiasm and may completely change the outlook of ARDS management in the near future.

Risk factors for developing ventilator-associated lower respiratory tract infection in patients with severe COVID-19: a multinational, multicentre study, prospective, observational study

Around one-third of patients diagnosed with COVID-19 develop a severe illness that requires admission to the Intensive Care Unit (ICU). In clinical practice, clinicians have learned that patients admitted to the ICU due to severe COVID-19 frequently develop ventilator-associated lower respiratory tract infections (VA-LRTI). This study aims to describe the clinical characteristics, the factors associated with VA-LRTI, and its impact on clinical outcomes in patients with severe COVID-19. This was a multicentre, observational cohort study conducted in ten countries in Latin America and Europe. We included patients with confirmed rtPCR for SARS-CoV-2 requiring ICU admission and endotracheal intubation. Only patients with a microbiological and clinical diagnosis of VA-LRTI were included. Multivariate Logistic regression analyses and Random Forest were conducted to determine the risk factors for VA-LRTI and its clinical impact in patients with severe COVID-19. In our study cohort of 3287 patients, VA-LRTI was diagnosed in 28.8% [948/3287]. The cumulative incidence of ventilator-associated pneumonia (VAP) was 18.6% [610/3287], followed by ventilator-associated tracheobronchitis (VAT) 10.3% [338/3287]. A total of 1252 bacteria species were isolated. The most frequently isolated pathogens were Pseudomonas aeruginosa (21.2% [266/1252]), followed by Klebsiella pneumoniae (19.1% [239/1252]) and Staphylococcus aureus (15.5% [194/1,252]). The factors independently associated with the development of VA-LRTI were prolonged stay under invasive mechanical ventilation, AKI during ICU stay, and the number of comorbidities. Regarding the clinical impact of VA-LRTI, patients with VAP had an increased risk of hospital mortality (OR [95% CI] of 1.81 [1.40-2.34]), while VAT was not associated with increased hospital mortality (OR [95% CI] of 1.34 [0.98-1.83]). VA-LRTI, often with difficult-to-treat bacteria, is frequent in patients admitted to the ICU due to severe COVID-19 and is associated with worse clinical outcomes, including higher mortality. Identifying risk factors for VA-LRTI might allow the early patient diagnosis to improve clinical outcomes.Trial registration: This is a prospective observational study; therefore, no health care interventions were applied to participants, and trial registration is not applicable.

Interferon gamma-1b for the prevention of hospital-acquired pneumonia in critically ill patients: a phase 2, placebo-controlled randomized clinical trial

PURPOSE

We aimed to determine whether interferon gamma-1b prevents hospital-acquired pneumonia in mechanically ventilated patients.

METHODS

In a multicenter, placebo-controlled, randomized trial conducted in 11 European hospitals, we randomly assigned critically ill adults, with one or more acute organ failures, under mechanical ventilation to receive interferon gamma-1b (100 µg every 48 h from day 1 to 9) or placebo (following the same regimen). The primary outcome was a composite of hospital-acquired pneumonia or all-cause mortality on day 28. The planned sample size was 200 with interim safety analyses after enrolling 50 and 100 patients.

RESULTS

The study was discontinued after the second safety analysis for potential harm with interferon gamma-1b, and the follow-up was completed in June 2022. Among 109 randomized patients (median age, 57 (41-66) years; 37 (33.9%) women; all included in France), 108 (99%) completed the trial. Twenty-eight days after inclusion, 26 of 55 participants (47.3%) in the interferon-gamma group and 16 of 53 (30.2%) in the placebo group had hospital-acquired pneumonia or died (adjusted hazard ratio (HR) 1.76, 95% confidence interval (CI) 0.94-3.29; P = 0.08). Serious adverse events were reported in 24 of 55 participants (43.6%) in the interferon-gamma group and 17 of 54 (31.5%) in the placebo group (P = 0.19). In an exploratory analysis, we found that hospital-acquired pneumonia developed in a subgroup of patients with decreased CCL17 response to interferon-gamma treatment.

CONCLUSIONS

Among mechanically ventilated patients with acute organ failure, treatment with interferon gamma-1b compared with placebo did not significantly reduce the incidence of hospital-acquired pneumonia or death on day 28. Furthermore, the trial was discontinued early due to safety concerns about interferon gamma-1b treatment.

Multiple-site decontamination to prevent acquired infection in patients with veno-venous ECMO support

BACKGROUND

Acute distress respiratory syndrome (ARDS) patients with veno-venous extra corporeal membrane oxygenation (ECMO) support are particularly exposed to ECMO-associated infection (ECMO-AI). Unfortunately, data regarding AI prophylaxis in this setting are lacking. Selective decontamination regimens decrease AI incidence, including ventilator-associated pneumonia (VAP) and bloodstream infection (BSI) in critically ill patients. We hypothesized that a multiple-site decontamination (MSD) regimen is associated with a reduction in the incidence of AI among VV-ECMO patients.

METHODS

We conducted a retrospective observational study in three French ECMO referral centers from January 2010 to December 2021. All adult patients (> 18 years old) who received VV-ECMO support for ARDS were eligible. In addition to standard care (SC), 2 ICUs used MSD, which consists of the administration of topical antibiotics four times daily in the oropharynx and the gastric tube, once daily chlorhexidine body-wash and a 5-day nasal mupirocin course. AIs were compared between the 2 ICUs using MSD (MSD group) and the last ICU using SC.

RESULTS

They were 241 patients available for the study. Sixty-nine were admitted in an ICU that applied MSD while the 172 others received standard care and constituted the SC group. There were 19 ECMO-AIs (12 VAP, 7 BSI) in the MSD group (1162 ECMO-days) compared to 143 AIs (104 VAP, 39 BSI) in the SC group (2376 ECMO-days), (p < 0.05 for all infection site). In a Poisson regression model, MSD was independently associated with a lower incidence of ECMO-AI (IRR = 0.42, 95% CI [0.23-0.60] p < 0.001). There were 30 multidrug resistant microorganisms (MDRO) acquisition in the SC group as compared with two in the MSD group (IRR = 0.13, 95% CI [0.03-0.56] p = 0.001). Mortality in ICU was similar in both groups (43% in the SC group vs 45% in the MSD group p = 0.90). Results were similar after propensity-score matching.

CONCLUSION

In this cohort of patients from different hospitals, MSD appeared to be safe in ECMO patients and may be associated with improved outcomes including lower ECMO-AI and MDRO acquisition incidences. Since residual confounders may persist, these promising results deserve confirmation by randomized controlled trials.

Complement as a vital nexus of the pathobiological connectome for acute respiratory distress syndrome: An emerging therapeutic target

The hallmark of acute respiratory distress syndrome (ARDS) pathobiology is unchecked inflammation-driven diffuse alveolar damage and alveolar-capillary barrier dysfunction. Currently, therapeutic interventions for ARDS remain largely limited to pulmonary-supportive strategies, and there is an unmet demand for pharmacologic therapies targeting the underlying pathology of ARDS in patients suffering from the illness. The complement cascade (ComC) plays an integral role in the regulation of both innate and adaptive immune responses. ComC activation can prime an overzealous cytokine storm and tissue/organ damage. The ARDS and acute lung injury (ALI) have an established relationship with early maladaptive ComC activation. In this review, we have collected evidence from the current studies linking ALI/ARDS with ComC dysregulation, focusing on elucidating the new emerging roles of the extracellular (canonical) and intracellular (non-canonical or complosome), ComC (complementome) in ALI/ARDS pathobiology, and highlighting complementome as a vital nexus of the pathobiological connectome for ALI/ARDS via its crosstalking with other systems of the immunome, DAMPome, PAMPome, coagulome, metabolome, and microbiome. We have also discussed the diagnostic/therapeutic potential and future direction of ALI/ARDS care with the ultimate goal of better defining mechanistic subtypes (endotypes and theratypes) through new methodologies in order to facilitate a more precise and effective complement-targeted therapy for treating these comorbidities. This information leads to support for a therapeutic anti-inflammatory strategy by targeting the ComC, where the arsenal of clinical-stage complement-specific drugs is available, especially for patients with ALI/ARDS due to COVID-19.

YAP-regulated type II alveolar epithelial cell differentiation mediated by human umbilical cord-derived mesenchymal stem cells in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) contributes to higher mortality worldwide. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) have immunomodulatory and regenerative potential. However, the effects of hUC-MSCs as an ARDS treatment remain unclear. We investigated the role of hUC-MSCs in the differentiation of type II alveolar epithelial cells (AECII) by regulating Yes-associated protein (YAP) in ARDS. Male C57BL/6JNarl mice were intratracheally (i.t.) administered lipopolysaccharide (LPS) to induce an ARDS model, followed by a single intravenous (i.v.) dose of hUC-MSCs. hUC-MSCs improved pulmonary function, decreased inflammation on day 3, and mitigated lung injury by reducing the lung injury score and increasing lung aeration (%) in mice on day 7 (p < 0.05). hUC-MSCs inactivated YAP on AECII and facilitated cell differentiation by decreasing Pro-surfactant protein C (Pro-SPC) and galectin 3 (LGALS3) while increasing podoplanin (T1α) in lungs of mice (p < 0.05). In AECII MLE-12 cells, both coculture with hUC-MSCs after LPS exposure and the YAP inhibitor, verteporfin, reduced Pro-SPC and LGALS3, whereas the YAP inhibitor increased T1α expression (p < 0.05). In conclusion, hUC-MSCs ameliorated lung injury of ARDS and regulated YAP to facilitate AECII differentiation.

Ventilator-Associated Pneumonia in COVID-19 Patients Admitted in Intensive Care Units: Relapse, Therapeutic Failure and Attributable Mortality-A Multicentric Observational Study from the OutcomeRea Network

Introduction: Ventilator-associated pneumonia (VAP) incidence is high among critically ill COVID-19 patients. Its attributable mortality remains underestimated, especially for unresolved episodes. Indeed, the impact of therapeutic failures and the determinants that potentially affect mortality are poorly evaluated. We assessed the prognosis of VAP in severe COVID-19 cases and the impact of relapse, superinfection, and treatment failure on 60-day mortality. Methods: We evaluated the incidence of VAP in a multicenter prospective cohort that included adult patients with severe COVID-19, who required mechanical ventilation for ≥48 h between March 2020 and June 2021. We investigated the risk factors for 30-day and 60-day mortality, and the factors associated with relapse, superinfection, and treatment failure. Results: Among 1424 patients admitted to eleven centers, 540 were invasively ventilated for 48 h or more, and 231 had VAP episodes, which were caused by Enterobacterales (49.8%), P. aeruginosa (24.8%), and S. aureus (22%). The VAP incidence rate was 45.6/1000 ventilator days, and the cumulative incidence at Day 30 was 60%. VAP increased the duration of mechanical ventilation without modifying the crude 60-day death rate (47.6% vs. 44.7% without VAP) and resulted in a 36% increase in death hazard. Late-onset pneumonia represented 179 episodes (78.2%) and was responsible for a 56% increase in death hazard. The cumulative incidence rates of relapse and superinfection were 45% and 39.5%, respectively, but did not impact death hazard. Superinfection was more frequently related to ECMO and first episode of VAP caused by non-fermenting bacteria. The risk factors for treatment failure were an absence of highly susceptible microorganisms and vasopressor need at VAP onset. Conclusions: The incidence of VAP, mainly late-onset episodes, is high in COVID-19 patients and associated with an increased risk of death, similar to that observed in other mechanically ventilated patients. The high rate of VAP due to difficult-to-treat microorganisms, pharmacokinetic alterations induced by renal replacement therapy, shock, and ECMO likely explains the high cumulative risk of relapse, superinfection, and treatment failure.

The Use of Extracorporeal Membrane Oxygenation for Burns: A Systematic Review and Meta-Analysis

Burns are among the leading causes of trauma worldwide, and acute respiratory distress syndrome (ARDS) is a common cause of death in burn patients. Some patients develop hypoxemia refractory to conventional therapies and may be initiated on extracorporeal membrane oxygenation (ECMO) as rescue therapy. We conducted a meta-analysis for studies reporting on survival rates of patients receiving ECMO for burns or inhalation injuries, which was the primary outcome. Secondary outcomes included the hospital and intensive care unit length of stay and duration of ECMO. Random-effects (DerSimonian and Laird) were conducted. The pooled survival from 10 studies was 53.6% (95% confidence interval [CI]: 37.6-69.2%, high certainty). Survival was significantly associated with age (regression coefficient [B]: -0.0088, 95% CI: -0.0155 to -0.0021, p = 0.011) and the proportion of male patients (B: -1.0137 95% CI: -1.9695 to -0.0580, p = 0.038). Patients were cannulated on ECMO for a mean of 8.4 days (95% CI: 6.1-10.7) and remained in the ICU for a mean of 40.4 days (95% CI: 11.4-69.3). Mean hospital length of stay was 45.4 days (95% CI: 31.7-59.0). In conclusion, patients with burn and inhalation injuries who develop ARDS refractory to conservative management have a survival rate of 54% when placed on ECMO.

Feasibility and mechanism analysis of Reduning in the prevention of sepsis-induced pulmonary fibrosis

Introduction: The increasing mortality in patients with sepsis-induced pulmonary fibrosis owes to a lack of effective treatment options. This study aims to explore the possibility and possible targets of Reduning in the prevention of sepsis-related pulmonary fibrosis. Methods: The active components and targets of Reduning were searched and screened from the database and analysis platform of traditional Chinese medicine (TCM) system pharmacology. GeneCards, human genome database, DisGeNET database, and the OMIM database were checked to determine the targets associated with sepsis-induced pulmonary fibrosis. DAVID Bioinformatics Resources 6.8 was used for GO and KEGG enrichment analysis to predict its possible signaling pathways and explore its molecular mechanism. The protein-protein interaction (PPI) network was used to identify key active components and core targets. Molecular docking technology was applied to screen the complexes with stable binding of key active components and core targets. Molecular dynamics simulations were used to verify the binding stability and molecular dynamics characteristics of the complexes. The protective effect of RDN on sepsis-induced pulmonary fibrosis was verified by in vitro and in vivo experiments. Results: There were 319 shared targets between sepsis-induced pulmonary fibrosis and RDN. GO enrichment analysis showed that they mainly regulated and participated in the positive regulation of kinase activity, mitogen-activated protein kinase (MAPK) cascade, and protein phosphorylation. KEGG enrichment analysis showed that they were mainly enriched in the mitogen-activated protein kinase cascade signaling pathway, the calcium signaling pathway, the apoptosis pathway, and other signaling pathways. The results of molecular docking and molecular dynamics simulations showed that the active components, stigmasterol, beta-sitosterol, and quercetin, had good binding activities with ERBB2, and they exhibited good stability. Molecular validation experiments confirmed RDN could alleviate lung fibrosis induced by cecum ligation and puncture (CLP), in parallel with the inhibition of the ERBB2-p38 MAPK pathway in mouse alveolar macrophages (AMs). Discussion: Reduning may prevent sepsis-induced pulmonary fibrosis by regulating the ERBB2-p38 MAPK signaling pathway, which provides a possibility for the prevention of sepsis-induced pulmonary fibrosis with traditional Chinese medicine.

Could the Lung Be a Gateway for Amphotericin B to Attack the Army of Fungi?

Fungal diseases are a significant cause of morbidity and mortality worldwide, primarily affecting immunocompromised patients. Aspergillus, Pneumocystis, and Cryptococcus are opportunistic fungi and may cause severe lung disease. They can develop mechanisms to evade the host immune system and colonize or cause lung disease. Current fungal infection treatments constitute a few classes of antifungal drugs with significant fungi resistance development. Amphotericin B (AmB) has a broad-spectrum antifungal effect with a low incidence of resistance. However, AmB is a highly lipophilic antifungal with low solubility and permeability and is unstable in light, heat, and oxygen. Due to the difficulty of achieving adequate concentrations of AmB in the lung by intravenous administration and seeking to minimize adverse effects, nebulized AmB has been used. The pulmonary pathway has advantages such as its rapid onset of action, low metabolic activity at the site of action, ability to avoid first-pass hepatic metabolism, lower risk of adverse effects, and thin thickness of the alveolar epithelium. This paper presented different strategies for pulmonary AmB delivery, detailing the potential of nanoformulation and hoping to foster research in the field. Our finds indicate that despite an optimistic scenario for the pulmonary formulation of AmB based on the encouraging results discussed here, there is still no product registration on the FDA nor any clinical trial undergoing ClinicalTrial.gov.

Analysis of clinical characteristics and prognostic factors of ARDS caused by community-acquired pneumonia in people with different immune status

BACKGROUND

The purpose of this study is to describe the clinical characteristics and prognostic risk factors of acute respiratory distress syndrome (ARDS) caused by community-acquired pneumonia under different immune states.

METHODS

The patients were divided into immunocompetent and immunocompromised groups according to their immune status. The basic clinical data of the two groups were collected and statistically analyzed, and the clinical characteristics and prognostic factors of ARDS caused by community-acquired pneumonia under different immune states were summarized.

RESULTS

128 patients with ARDS caused by community-acquired pneumonia were enrolled. The chest High-Resolution Computed Tomography (HRCT) scores of patients with immunosuppression were higher (236.0 ± 55.0 vs. 207.5 ± 49.6, p < 0.05) and the score of APACHE II was higher (17.3 ± 4.8 vs. 15.1 ± 5.4, p < 0.05). The 28-day intensive care unit (ICU) mortality was higher in the immunocompromised group (54.5% vs. 34.7%, p = 0.045). The 28-day in-hospital mortality in the immunocompetent group was mainly related to NLR and the oxygenation index. The 28-day in-hospital mortality in the immunocompromised group was mainly related to LDH and APACHE II.

CONCLUSION

There are differences in clinical characteristics and mortality of ARDS patients caused by community-acquired pneumonia under different immune states.

Targeted delivery of an anti-inflammatory corticosteroid to Ly6C/G-positive cells abates severity of influenza A symptoms

The distribution of Ly6C/G-positive cells in response to an infection of the mouse respiratory tract with influenza A virus was followed noninvasively over time by immuno-positron emission tomography. We converted nanobodies that recognize Ly6C and Ly6G, markers of neutrophils and other myeloid cells, as well as an influenza hemagglutinin-specific nanobody, into ⁸⁹Zr-labeled PEGylated positron emission tomography (PET) imaging agents. The PET images showed strong accumulation of these imaging agents in the lungs of infected mice. Immunohistochemistry of influenza virus-infected mice and control mice, injected with a biotinylated and PEGylated version of the Ly6C/G-specific nanobody, showed the presence of abundant Ly6C/G-positive myeloid cells and positivity for Ly6C/G on bronchial epithelium in influenza virus-infected mice. This is consistent with focal inflammation in the lungs, a finding that correlated well with the immuno-PET results. No such signals were detected in control mice. Having shown by PET the accumulation of the Ly6C/G-specific nanobody in infected lungs, we synthesized conjugates of Ly6C/G-specific nanobodies with dexamethasone to enable targeted delivery of this immunosuppressive corticosteroid to sites of inflammation. Such conjugates reduced the weight loss that accompanies infection, while the equivalent amount of free dexamethasone was without effect. Nanobody-drug conjugates thus enable delivery of drugs to particular cell types at the appropriate anatomic site(s). By avoiding systemic exposure to free dexamethasone, this strategy minimizes its undesirable side effects because of the much lower effective dose of the nanobody-dexamethasone conjugate. The ability to selectively target inflammatory cells may find application in the treatment of other infections or other immune-mediated diseases.

Nosocomial infections during extracorporeal membrane oxygenation

PURPOSE OF THE REVIEW

The aim of this review is to present the latest evidence regarding the prevention, diagnosis and treatment of nosocomial infections during extracorporeal membrane oxygenation (ECMO) support.

RECENT FINDINGS

New descriptive data from the Extracorporeal Life Support Organisation (ELSO) registry and single centre studies have been published. In parallel, there is an increase in the availability of evidence about the diagnostic accuracy of infection markers, yield of routine cultures, effectivity of antibiotic prophylaxis and other preventive measures.

SUMMARY

ECMO is a rescue therapy for severe hemodynamic or respiratory failure. Nosocomial infections on ECMO support are frequent (infection rate ranging between 20.5% to more than 50% of ECMO runs) and have impact in survival, with reported increases in the risk of death up to 63% in infected patients. However, diagnosis and treatment are challenging, as the unique relationship between patient and circuit may act as a confounder for infection and exacerbate the variability of antibiotic pharmacokinetics in critical illness. Clinical practice regarding antibiotic treatment and infection prevention is not yet supported by high-quality evidence.

Bacterial infection in coronavirus disease 2019 patients: co-infection, super-infection and how it impacts on antimicrobial use

PURPOSE OF REVIEW

Since the beginning of the severe acute respiratory syndrome coronavirus 2 pandemic, there has been a large increase in the consumption of antimicrobials, both as a form of treatment for viral pneumonia, which has been shown to be ineffective, and in the treatment of secondary infections that arise over the course of the severe presentation of coronavirus disease 2019 (COVID-19). This increase in consumption, often empirical, ends up causing an increase in the incidence of colonization and secondary infections by multi and pan-resistant germs.

RECENT FINDINGS

The presence of a hyperinflammatory condition induced by the primary infection, associated with the structural damage caused by viral pneumonia and by the greater colonization by bacteria, generally multiresistant, are important risk factors for the acquisition of secondary infections in COVID-19. Consequently, there is an increased prevalence of secondary infections, associated with a higher consumption of antimicrobials and a significant increase in the incidence of infections by multi and pan-resistant bacteria.

SUMMARY

Antimicrobial stewardship and improvement in diagnostic techniques, improving the accuracy of bacterial infection diagnosis, may impact the antibiotic consumption and the incidence of infections by resistant pathogens.

Relationship between corticosteroid use and incidence of ventilator-associated pneumonia in COVID-19 patients: a retrospective multicenter study

Background

Ventilator-associated pneumonia (VAP) is common in patients with severe SARS-CoV-2 pneumonia. The aim of this ancillary analysis of the coVAPid multicenter observational retrospective study is to assess the relationship between adjuvant corticosteroid use and the incidence of VAP.

Methods

Planned ancillary analysis of a multicenter retrospective European cohort in 36 ICUs. Adult patients receiving invasive mechanical ventilation for more than 48 h for SARS-CoV-2 pneumonia were consecutively included between February and May 2020. VAP diagnosis required strict definition with clinical, radiological and quantitative microbiological confirmation. We assessed the association of VAP with corticosteroid treatment using univariate and multivariate cause-specific Cox’s proportional hazard models with adjustment on pre-specified confounders.

Results

Among the 545 included patients, 191 (35%) received corticosteroids. The proportional hazard assumption for the effect of corticosteroids on the incidence of VAP could not be accepted, indicating that this effect varied during ICU stay. We found a non-significant lower risk of VAP for corticosteroid-treated patients during the first days in the ICU and an increased risk for longer ICU stay. By modeling the effect of corticosteroids with time-dependent coefficients, the association between corticosteroids and the incidence of VAP was not significant (overall effect p = 0.082), with time-dependent hazard ratios (95% confidence interval) of 0.47 (0.17–1.31) at day 2, 0.95 (0.63–1.42) at day 7, 1.48 (1.01–2.16) at day 14 and 1.94 (1.09–3.46) at day 21.

Conclusions

No significant association was found between adjuvant corticosteroid treatment and the incidence of VAP, although a time-varying effect of corticosteroids was identified along the 28-day follow-up.

Herpesviridae lung reactivation and infection in patients with severe COVID-19 or influenza virus pneumonia: a comparative study

Background

Lung reactivations of Herpesviridae, herpes simplex virus (HSV) and cytomegalovirus (CMV) have been reported in COVID-19 patients. Whether or not those viral reactivations are more frequent than in other patients is not known.

Methods

Retrospective monocentric cohort study of 145 patients with severe COVID-19 pneumonia requiring invasive mechanical ventilation and who were tested for HSV and CMV in bronchoalveolar lavage performed during fiberoptic bronchoscopy for ventilator-associated pneumonia suspicion. Rates of HSV and CMV lung reactivations, and HSV bronchopneumonitis were assessed and compared with an historical cohort of 89 patients with severe influenza pneumonia requiring invasive mechanical ventilation.

Results

Among the 145 COVID-19 patients included, 50% and 42% had HSV and CMV lung reactivations, respectively, whereas among the 89 influenza patients, 63% and 28% had HSV and CMV lung reactivations, respectively. Cumulative incidence of HSV lung reactivation (taking into account extubation and death as competing events) was higher in influenza than in COVID-19 patients (p = 0.03), whereas the rate of HSV bronchopneumonitis was similar in both groups (31% and 25%, respectively). Cumulative incidence of CMV lung reactivation (taking into account extubation and death as competing events) was similar in COVID-19 and influenza patients (p = 0.07). Outcomes of patients with HSV or CMV lung reactivations were similar to that of patients without, whatever the underlying conditions, i.e., in COVID-19 patients, in influenza patients, or when all patients were grouped.

Conclusions

HSV and CMV lung reactivations are frequent in COVID-19 patients, but not more frequent than in patients with influenza-associated severe pneumonia, despite a higher severity of illness at intensive care unit admission of the latter and a longer duration of mechanical ventilation of the former. Although no impact on outcome of HSV and CMV lung reactivations was detected, the effect of antiviral treatment against these Herpesviridae remains to be determined in these patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01062-0.

Frontline workers: Mediators of mucosal immunity in community acquired pneumonia and COVID-19

The current COVID-19 pandemic has highlighted a need to further understand lung mucosal immunity to reduce the burden of community acquired pneumonia, including that caused by the SARS-CoV-2 virus. Local mucosal immunity provides the first line of defence against respiratory pathogens, however very little is known about the mechanisms involved, with a majority of literature on respiratory infections based on the examination of peripheral blood. The mortality for severe community acquired pneumonia has been rising annually, even prior to the current pandemic, highlighting a significant need to increase knowledge, understanding and research in this field. In this review we profile key mediators of lung mucosal immunity, the dysfunction that occurs in the diseased lung microenvironment including the imbalance of inflammatory mediators and dysbiosis of the local microbiome. A greater understanding of lung tissue-based immunity may lead to improved diagnostic and prognostic procedures and novel treatment strategies aimed at reducing the disease burden of community acquired pneumonia, avoiding the systemic manifestations of infection and excess morbidity and mortality.

IFN-γ transforms the transcriptomic landscape and triggers myeloid cell hyperresponsiveness to cause lethal lung injury

Acute Respiratory Distress Syndrome (ARDS) is an inflammatory disease that is associated with high mortality but no specific treatment. Our understanding of initial events that trigger ARDS pathogenesis is limited. We have developed a mouse model of inflammatory lung injury by influenza and methicillin-resistant Staphylococcus aureus (MRSA) coinfection plus daily antibiotic therapy. Using this pneumonic ARDS model, here we show that IFN-γ receptor signaling drives inflammatory cytokine storm and lung tissue damage. By single-cell RNA sequencing (scRNA-seq) analysis, we demonstrate that IFN-γ signaling induces a transcriptional shift in airway immune cells, particularly by upregulating macrophage and monocyte expression of genes associated with inflammatory diseases. Further evidence from conditional knockout mouse models reveals that IFN-γ receptor signaling in myeloid cells, particularly CD11c+ mononuclear phagocytes, directly promotes TNF-α hyperproduction and inflammatory lung damage. Collectively, the findings from this study, ranging from cell-intrinsic gene expression to overall disease outcome, demonstrate that influenza-induced IFN-γ triggers myeloid cell hyperresponsiveness to MRSA, thereby leading to excessive inflammatory response and lethal lung damage during coinfection.