The epidemiology of acute respiratory distress syndrome in patients presenting to the emergency department with severe sepsis

Risk factors for mortality in children with moderate-to-severe ARDS with concurrent hematological or immune-related diseases: a retrospective analysis

BACKGROUND

As a heterogeneous syndrome, acute respiratory distress syndrome (ARDS) patients with comorbidities are significantly more severely ill. We aim to investigate the clinical characteristics and analyze the risk factors for mortality in children with moderate-to-severe acute respiratory distress syndrome (ARDS) who also have concurrent hematological or immune-related diseases.

METHODS

A retrospective observational study was conducted from September 2020 to May 2022 in the pediatric intensive care unit (PICU) at Children's Hospital of Chongqing Medical University (Chongqing, China). All children with moderate-to-severe ARDS were included and divided into two groups based on the presence or absence of hematological or immune-related diseases. Clinical characteristics, treatment, and outcome data were collected. Univariate logistic regression and multivariate Firth regression analysis were used to identify risk factors for mortality in children with moderate-to-severe ARDS with concurrent hematological or immune-related diseases.

RESULTS

A total of 215 children with moderate-to-severe ARDS were included in the study, of whom 65 had hematological or immune-related diseases (30.2%). These children were older (p < 0.001), had higher Pediatric Index of Mortality 3 scores (p = 0.002), higher lactate levels (p = 0.042), higher rates of positive pathogen detection (p < 0.001), shorter PICU stay (p = 0.023), higher incidence of multiple organ dysfunction syndrome (p = 0.012), and higher 28-day mortality rates (p < 0.001). Firth regression analysis showed that invasive fungal infection (OR = 4.954, 95% CI 0.245-3.158, p < 0.05), use of vasoactive drugs (OR = 7.638, 95% CI 0.524-3.811, p < 0.05), and high-frequency oscillatory ventilation (OR = 6.551, 95% CI 0.134-3.908, p < 0.05) were associated with increased mortality rates in children with moderate-to-severe ARDS with concurrent hematological or immune-related diseases.

CONCLUSION

The incidence of moderate-to-severe ARDS is higher in children with concurrent hematological or immune-related diseases, and their prognosis is worse. In this group, children with invasive fungal infections, greater use of vasoactive drugs, or high-frequency oscillatory ventilation had a higher 28-day mortality rate.

SEX DIFFERENCES IN SEPSIS-RELATED ACUTE RESPIRATORY DISTRESS SYNDROME AND OTHER SHORT-TERM OUTCOMES AMONG CRITICALLY ILL PATIENTS WITH SEPSIS: A RETROSPECTIVE STUDY IN CHINA

ABSTRACT

Background: The evidence of sex disparity in acute respiratory distress syndrome (ARDS) is scarce and varies widely. Objective: This observational, retrospective study aimed to determine the effect of sex on the sepsis-related ARDS and other short outcomes in critically ill patients with sepsis. Methods: A total of 2,111 adult patients with sepsis who were admitted to three central intensive care units (ICUs) of Wuhan Tongji Hospital between 2012 and 2022 were included in our analysis. Sex was considered as an exposure factor, with sepsis-related ARDS as the primary outcome, and in-hospital mortality, invasive mechanical ventilation support, septic shock, and other complications as secondary outcomes. Results: Among the 2,111 enrolled patients, 1,287 were males (61%) and 824 were females (39%). The incidence of sepsis-related ARDS was higher in males compared to females ( P = 0.001), as well as in-hospital mortality ( P = 0.009). Multivariate logistic analysis demonstrated that male sex remained independently associated with an increased risk of sepsis-related ARDS (adjusted odds ratio [aOR] = 1. 493 [1.034-2.156], P = 0.032). Propensity score matching analysis also indicated that males had 58% higher odds of developing sepsis-related ARDS (aOR = 1.584 [1.022-2.456], P = 0.040). Regarding secondary outcomes, male sex was identified as a risk factor for in-hospital mortality (aOR = 1.536 [1.087-2.169], P = 0.015) and invasive mechanical ventilation support (aOR = 1.313 [1.029-1.674], P = 0.028) in the fully adjusted model. Sensitivity analysis that included postmenopausal females and age-matched male counterparts showed that male sex still remained to be a risk factor of developing sepsis-related ARDS (aOR = 1.968 [1.241-3.120], P = 0.004). Conclusions: Male sex was identified as an independent risk factor for sepsis-related ARDS and in-hospital mortality among critically ill patients with sepsis. Given the retrospective design of this study, the relationship between sex and sepsis-related ARDS requires further validation through large-scale randomized controlled trials in the future.

ATG16L1 restrains macrophage NLRP3 activation and alveolar epithelial cell injury during septic lung injury

BACKGROUND

The lung is the organ most commonly affected by sepsis. Additionally, acute lung injury (ALI) resulting from sepsis is a major cause of death in intensive care units. Macrophages are essential for maintaining normal lung physiological functions and are implicated in various pulmonary diseases. An essential autophagy protein, autophagy-related protein 16-like 1 (ATG16L1), is crucial for the inflammatory activation of macrophages.

METHODS

ATG16L1 expression was measured in lung from mice with sepsis. ALI was induced in myeloid ATG16L1-, NLRP3- and STING-deficient mice by intraperitoneal injection of lipopolysaccharide (LPS, 10 mg/kg). Using immunofluorescence and flow cytometry to assess the inflammatory status of LPS-treated bone marrow-derived macrophages (BMDMs). A co-culture system of BMDMs and MLE-12 cells was established in vitro.

RESULTS

Myeloid ATG16L1-deficient mice exhibited exacerbated septic lung injury and a more intense inflammatory response following LPS treatment. Mechanistically, ATG16L1-deficient macrophages exhibited impaired LC3B lipidation, damaged mitochondria and reactive oxygen species (ROS) accumulation. These abnormalities led to the activation of NOD-like receptor family pyrin domain-containing protein 3 (NLRP3), subsequently enhancing proinflammatory response. Overactivated ATG16L1-deficient macrophages aggravated the damage to alveolar epithelial cells and enhanced the release of double-stranded DNA (dsDNA), thereby promoting STING activation and subsequent NLRP3 activation in macrophages, leading to positive feedback activation of macrophage NLRP3 signalling. Scavenging mitochondrial ROS or inhibiting STING activation effectively suppresses NLRP3 activation in macrophages and alleviates ALI. Furthermore, overexpression of myeloid ATG16L1 limits NLRP3 activation and reduces the severity of ALI.

CONCLUSIONS

Our findings reveal a new role for ATG16L1 in regulating macrophage NLRP3 feedback activation during sepsis, suggesting it as a potential therapeutic target for treating sepsis-induced ALI.

KEY POINTS

Myeloid-specific ATG16L1 deficiency exacerbates sepsis-induced lung injury. ATG16L1-deficient macrophages exhibit impaired LC3B lipidation and ROS accumulation, leading to NLRP3 inflammasome activation. Uncontrolled inflammatory responses in ATG16L1-deficient macrophages aggravate alveolar epithelial cell damage. Alveolar epithelial cells release dsDNA, activating the cGAS-STING-NLRP3 signaling pathway, which subsequently triggers a positive feedback activation of NLRP3. Overexpression of ATG16L1 helps mitigate lung tissue inflammation, offering a novel therapeutic direction for sepsis-induced lung injury.

Association between the triglyceride glucose index and the risk of acute respiratory failure in patients with acute pancreatitis

BACKGROUND

The triglyceride glucose (TyG) index serves as a dependable marker for insulin resistance and has shown a significant correlation with the severity of acute pancreatitis (AP). However, no research exists regarding the association between the TyG index and the development of acute respiratory failure (ARF) in AP. This study assesses the association between TyG index and ARF in patients with AP.

METHODS

Retrospective cohort analysis was conducted with the MIMIC-IV 2.2 critical care data. The endpoint focused on ARF during hospitalization. Statistical analysis encompassed univariate and multivariate logistic regressions, alongside restricted cubic spline (RCS) analysis to explore potential nonlinear associations. Receiver operating characteristic (ROC) curve analysis was employed to identify the optimal TyG index cutoff, leading to the classification of patients into Low TyG and High TyG groups. Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were subsequently applied to minimize the influence of confounding factors, thereby further clarifying the relationship between the TyG index and ARF in patients with AP.

RESULTS

A total of 758 patients were involved in this study, the incidence of ARF was 21.64%. Logistic regression analyses demonstrated a significant association between the TyG index and the incidence of ARF in patients with AP. The RCS model illustrated a nonlinear relationship between a higher TyG index and an increased risk of ARF. The cutoff value of TyG index was 9.099 for ARF in patients with AP based on the ROC curve analysis. Furthermore, following PSM and IPTW, multivariate logistic regression analysis indicated that the High TyG group exhibited a significantly higher risk of ARF compared to the Low TyG group (P < 0.05).

CONCLUSIONS

The TyG index is associated with ARF risk in AP patients and may aid in early risk assessment.

Role of inflammasomes in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is present in >10% of all people admitted to critical care and is associated with severe morbidity and mortality. Despite more than half a century since its first description, no efficacious pharmacological therapies have been developed, and little progress has been made in improving clinical outcomes. Neutrophils are the principal drivers of ARDS, with their priming and subsequent aberrant downstream functions, including interleukin (IL) 1β and IL-18 secretion, central to the disease pathogenesis. The dominant pathways through which IL-1β and IL-18 are believed to be elaborated are multimeric protein structures called inflammasomes that consist of sensor proteins, adaptor proteins and an effector enzyme. The inflammasome's initial activation depends on one of a variety of damage-associated (DAMP) or pathogen-associated (PAMP) molecular patterns. However, once activated, a common downstream inflammatory pathway is initiated regardless of the specific DAMP or PAMP involved. Several inflammasomes exist in humans. The nucleotide-binding domain leucine-rich repeat (NLR) family, pyrin domain-containing 3 (NLRP3), inflammasome is the best described in the context of ARDS and is known to be activated in both infective and sterile cases. The NLR family, caspase activation and recruitment domain-containing 4 (NLRC4) and absent in melanoma 2 (AIM2) inflammasomes have also been implicated in various ARDS settings, as have inflammasome-independent pathways. Further work is required to understand human biology as much of our knowledge is extrapolated from rodent experimental models. Experimental lung injury models have demonstrated beneficial responses to inflammasome, IL-1β and IL-18 blockade. However, findings have yet to be successfully translated into humans with ARDS, likely due to an underappreciation of the central role of the neutrophil inflammasome. A thorough understanding of inflammasome pathways is vital for critical care clinicians and researchers and for the development of beneficial therapies. In this review, we describe the central role of the inflammasome in the development of ARDS and its potential for immunomodulation, highlighting key areas for future research.

Comparison of high-flow nasal oxygen therapy and noninvasive ventilation in suspected sepsis patients with acute respiratory distress in the emergency department: a retrospective cohort study

INTRODUCTION

High-flow nasal cannula (HFNC) and non-invasive ventilation (NIV) are widely utilized respiratory support modalities for patients presenting with suspected sepsis and respiratory distress.This study aims to compare the 48-hour intubation rates between HFNC and NIV therapies in patients with suspected sepsis and respiratory distress.

METHODS

This retrospective cohort study collected data over a 2-year period (January 2022 to December 2023) from patients presenting to the ED of Ramathibodi Hospital with suspected sepsis who received respiratory support with either HFNC or NIV. To analyze the incidence of intubation and 28-day mortality, we employed multivariable Cox regression to estimate hazard ratios (HRs). The hospital length of stay and ventilator-free days at 28 days were compared using Gaussian regression analysis.

RESULTS

A total of 546 patients met the inclusion criteria. The intubation at 48 h was 17.39% in the HFNC group and 19.47% in the NIV group (adjusted HR 0.74; 95% CI, 0.48 to 1.15; p = 0.18). The HFNC group demonstrated a trend toward lower 28-day mortality than the NIV group (adjusted HR 0.34; 95% CI, 0.12 to 1.02; p = 0.053). Additionally, the HFNC group had significantly more ventilator-free days (adjusted mean difference 1.46 days; 95% CI, 0.11 to 2.80; p = 0.034).

CONCLUSIONS

In patients with suspected sepsis and acute respiratory distress, HFNC therapy did not significantly reduce the 48-hour intubation compared to NIV. However, HFNC was associated with a trend toward lower 28-day mortality and a significantly greater number of ventilator-free days on day 28.

TRIAL REGISTRATION

This trial was retrospectively registered in the Thai Clinical Trial Registry on 09 November 2023. The TCTR identification number is TCTR20231109004.

Autophagy-related biomarkers identified in sepsis-induced ARDS through bioinformatics analysis

While dysregulated autophagy has been linked to acute respiratory distress syndrome (ARDS) development in sepsis, the exact regulatory mechanisms driving this process remain unclear. This study systematically investigated autophagy-related genes in sepsis-induced ARDS using integrative bioinformatics, including weighted gene coexpression network analysis (WGCNA), differential gene expression analysis (DEGs), receiver operating characteristic (ROC) curve analysis, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, protein‒protein interaction (PPI) network analysis, and immune infiltration analysis. Hub genes were further validated by qPCR in Beas-2B cells receiving lipopolysaccharide (LPS) stimulation. We identified 18 autophagy-related DEGs with diagnostic potential for sepsis-induced ARDS. These DEGs were linked to endocytosis, protein kinase inhibition, and enigmatic Ficolin-1-rich granules. The downregulated hallmark signaling pathways involved apoptosis, complement, IL-2/STAT5, and KRAS signaling. Immune infiltration analysis revealed alterations in 7 immune cell subsets, including CD8 + T-cell exhaustion, natural killer cell reduction, and the type 1 helper T-cell response. When Beas-2B cells were treated with LPS, we discovered that 6 out of the 18 hub genes were significantly downregulated. Our findings provide novel insights into autophagy-mediated ARDS pathogenesis in sepsis. The hub genes represent promising candidates for clinical biomarker development and therapeutic targeting, which necessitates further validation.

End-Expiratory Occlusion Test and Tidal Volume Challenge Test for Evaluating Fluid Responsiveness in Severe Traumatic Brain Injury, Septic Shock, and Acute Respiratory Distress Syndrome

INTRODUCTION

Fluid management in critically ill patients, particularly those with severe traumatic brain injury (TBI), septic shock, and acute respiratory distress syndrome (ARDS), presents a complex and multifaceted challenge. Dynamic tests such as the end-expiratory occlusion (EEO) test and tidal volume challenge (TVC) test are commonly used to assess fluid responsiveness, providing valuable insights into cardiovascular responses to changes in volume status. However, due to the unique risks and complications associated with these conditions, there is an increasing need to explore and evaluate alternative methods for predicting fluid responsiveness more safely and accurately in these critically ill patients.

METHODS

This study presents a prospective investigation conducted on patients with severe TBI, septic shock, and ARDS. Before administering a 100 mL colloid bolus, both the EEO and TVC tests were performed. Initial measurements of cardiac output (CO), cardiac index (CI), and pulse pressure variation (PPV) were recorded, followed by subsequent measurements after each test to assess the fluid responsiveness and cardiovascular changes in these critically ill patients.

RESULTS

Among the 180 participants, a more than 5% increase in CI during the EEO test was indicative of fluid responsiveness. Similarly, a 3.5% absolute increase in PPV during the TVC test suggested fluid responsiveness. The interrater reliability for the EEO test was observed to be 0.915, indicating strong agreement between raters, while for PPV, it was 0.637, reflecting moderate agreement. These values suggest that the EEO test shows a high degree of consistency between different evaluators, whereas the PPV measurement demonstrates a more moderate level of reliability.

CONCLUSION

In patients with severe TBI, septic shock, and ARDS who are receiving low tidal volume (VT) ventilation, both the EEO test for 15 seconds and the TVC method can be used to assess fluid responsiveness. However, it is important to note that the EEO test demonstrates greater reliability in this context.

INDUCTION OF EARLY PULMONARY SENESCENCE IN EXPERIMENTAL SEPSIS

ABSTRACT

Background: Sepsis continues to pose a significant threat to human life and represents a substantial financial burden. In addition to replicative stress resulting from telomeric loss, recent studies have identified multiple factors contributing to cell cycle arrest. Furthermore, our understanding of pathways associated with cellular senescence, such as CD47-mediated suppression of efferocytosis, has expanded. However, beyond in vitro experiments, the impact of cell stress during complex systemic illnesses, including sepsis, remains poorly understood. Consequently, we conducted an investigation into molecular alterations related to senescence-associated pulmonary mechanisms during experimental nonpulmonary sepsis. Methods: Male C57BL/6JRj mice were anesthetized and subjected to either control conditions (sham) or cecal ligation and puncture (CLP) to induce sepsis. Twenty-four hours or 7 d after CLP, animals were killed, and blood, bronchoalveolar fluids, and lungs were harvested and analyzed for morphological and biochemical changes. Results: Histological damage in pulmonary tissue, as well as increases in plasma levels of surfactant protein D, indicated development of alveolar-focused acute lung injury after CLP. Additionally, we observed a significant upregulation of the CD47-QPCTL-SHP-1 axis in lungs of septic mice. Whereas the expression of p16, a marker primarily indicating manifested forms of senescence, was decreased after CLP, the early marker of cellular senescence, p21, was increased in the lungs during sepsis. Later, at 7 d after CLP, pulmonary expression of CD47 and QPCTL-1 was decreased, whereas SHP-1 was significantly enhanced. Conclusion: Our findings suggest an activation of senescent-associated pathways during experimental sepsis. However, expanding the experiments to other organ systems and in vivo long-term models are necessary to further evaluate the sustained mechanisms and immunopathophysiological consequences of cellular senescence triggered by septic organ injury.

Circular RNA-Cacna1d Plays a Critical Role in Sepsis-induced Lung Injury by Sponging microRNA-185-5p

The role of circular RNAs (circRNAs) in sepsis-induced lung injury is not clear. This study investigated the role and molecular mechanism of a novel circRNA in sepsis-induced lung injury and explored its prognostic value in patients with sepsis. In this study, aberrant circRNA expression profiling in lung tissues from mice with sepsis-induced lung injury was analyzed using high-throughput sequencing. circRNA-Cacna1d was verified by qRT-PCR, and its biological function in sepsis-induced lung injury was validated in vitro and in vivo. The interactions among circRNA-Cacna1d, microRNAs (miRNAs), and their downstream genes were verified. Furthermore, the clinical value of circRNA-Cacna1d in peripheral blood from patients with sepsis was also evaluated. We found that circRNA-Cacna1d expression was significantly increased in lung tissues of mice with sepsis and in microvascular endothelial cells after LPS challenge. circRNA-Cacna1d knockdown alleviated inflammatory response and ameliorated the permeability of vascular endothelium, thereby mitigating sepsis-induced lung injury and significantly improving the survival rate of mice with sepsis. Mechanistically, circRNA-Cacna1d directly interacted with miRNA-185-5p and functioned as a miRNA sponge to regulate the RhoA/ROCK1 signaling pathway. The expression level of circRNA-Cacna1d in patients with early sepsis was significantly higher than that in the healthy control subjects. Higher levels of circRNA-Cacna1d in patients with sepsis were associated with increased disease severity and poorer outcomes. In conclusions, circRNA-Cacna1d may play a role in sepsis-induced lung injury by regulating the RhoA/ROCK1 axis by acting as a miRNA-185-5p sponge. circRNA-Cacna1d is a potential therapeutic target for sepsis-induced lung injury and a prognostic biomarker in sepsis.

Dexmedetomidine attenuates sepsis-associated acute lung injury by regulating macrophage efferocytosis through the ROS/ADAM10/AXL pathway

BACKGROUND

The lungs are highly susceptible to damage during sepsis, with severe lung injury potentially progressing to acute respiratory distress syndrome and even fatal sepsis. Effective efferocytosis of apoptotic cells is crucial in alleviating inflammation and tissue injury.

METHODS

We established a septic lung injury mouse model via intraperitoneal injection of lipopolysaccharide. Lung injury was assessed by histology, immunofluorescence, neutrophil immunohistochemistry staining, and cytokine detection. We extracted alveolar macrophages by bronchoalveolar lavage and primary macrophages from mouse bone marrow to investigate the regulatory effects of Dexmedetomidine (DEX) on efferocytosis. We further validated the molecular mechanisms underlying the regulation of macrophage efferocytosis by DEX through knockdown of AXL expression. Additionally, we examined the efferocytic ability of monocytes isolated from patients.

RESULTS

We discovered that DEX treatment effectively alleviated pulmonary injury and inflammation. Lipopolysaccharide reduced macrophage efferocytosis and AXL expression which were reversed by DEX. We also found DEX inhibited the increased activation of A Disintegrin And Metalloproteinase 10 (ADAM10) and the production of soluble AXL. Moreover, our findings demonstrated that DEX decreased the elevated ROS production linked to higher ADAM10 activation. Blocking AXL negated DEX's benefits on efferocytosis and lung protection. Efferocytosis in monocytes from septic lung injury patients was notably lower than in healthy individuals.

CONCLUSION

Our findings demonstrated that DEX treatment effectively reduces septic lung injury by promoting macrophage efferocytosis through ROS/ADAM10/AXL signaling pathwway.

Throat microbiota drives alterations in pulmonary alveolar microbiota in patients with septic ARDS

OBJECTIVES

The translocation of intestinal flora has been linked to the colonization of diverse and heavy lower respiratory flora in patients with septic ARDS, and is considered a critical prognostic factor for patients.

METHODS

On the first and third days of ICU admission, BALF, throat swab, and anal swab were collected, resulting in a total of 288 samples. These samples were analyzed using 16S rRNA analysis and the traceability analysis of new generation technology.

RESULTS

On the first day, among the top five microbiota species in abundance, four species were found to be identical in BALF and throat samples. Similarly, on the third day, three microbiota species were found to be identical in abundance in both BALF and throat samples. On the first day, 85.16% of microorganisms originated from the throat, 5.79% from the intestines, and 9.05% were unknown. On the third day, 83.52% of microorganisms came from the throat, 4.67% from the intestines, and 11.81% were unknown. Additionally, when regrouping the 46 patients, the results revealed a significant predominance of throat microorganisms in BALF on both the first and third day. Furthermore, as the disease progressed, the proportion of intestinal flora in BALF increased in patients with enterogenic ARDS.

CONCLUSIONS

In patients with septic ARDS, the main source of lung microbiota is primarily from the throat. Furthermore, the dynamic trend of the microbiota on the first and third day is essentially consistent.It is important to note that the origin of the intestinal flora does not exclude the possibility of its origin from the throat.

Subphenotypic features of patients with sepsis and ARDS: a multicenter cohort study

Objectives

Patients with sepsis are often comorbid with acute respiratory distress syndrome (ARDS), and the phenotypic characteristics of pulmonary and non-pulmonary infections leading to ARDS are still unclear. This study aimed to compare the phenotypic characteristics of ARDS resulting from pulmonary infections and other non-site infections and provide better guidance for clinical treatment.

Methods

We conducted a multicenter cohort analysis using data from the Tianjin Medical University General Hospital, Medical Information Mart for Intensive Care-IV (MIMIC-IV), and the electronic intensive care unit (eICU) databases. The study population consisted of adult patients diagnosed with sepsis and ARDS. The primary objectives were to compare the characteristics and outcomes of patients with pulmonary infection-induced ARDS and those with non-pulmonary infection-induced ARDS using Wilcoxon analysis, Kaplan-Meier curves, correlation analysis, propensity matching scores, and other statistical methods.

Results

Patients with ARDS by pulmonary infection may be more likely to have a history of chronic obstructive pulmonary disease, and abdominal infection was more likely to induce ARDS in sepsis patients with non-pulmonary infection. Pulmonary infections caused by Klebsiella pneumoniae and Acinetobacter baumannii were more likely to induce ARDS. The oxygenation index and prognosis of ARDS patients induced by pulmonary infection were worse than those caused by other infections, with lower PaO2, PaO2/FiO2, and ROX index and longer hospital stay. More ARDS patients with pulmonary infection were given mechanical ventilation therapy, with higher mortality, APACHE II, SOFA, and SAPS II. The further correlation analysis showed that the prognostic scores of ARDS patients were negatively correlated with PaO2/FiO2 and ROX index. The above results were confirmed to varying degrees by propensity matching scores, external cohort validation, and other methods.

Conclusion

Pulmonary infection induces a worse prognosis of ARDS than other site infections in patients with sepsis and ARDS. These patients require heightened vigilance, early intervention, and possibly more aggressive management strategies.

Risk factors for acute respiratory distress syndrome in sepsis patients: A meta-analysis

Background

Acute Respiratory Distress Syndrome (ARDS) is a critical complication of sepsis, associated with high morbidity and mortality. Identifying risk factors for ARDS among sepsis patients is essential for early intervention and improving outcomes.

Methods

We conducted a comprehensive meta-analysis, reviewing studies that examined the association between various risk factors and ARDS development in sepsis patients. Databases such as PubMed, EMBASE, Cochrane Library, Medline, CINAHL, and Web of Science were searched up to January 2024, without language restrictions. Eligible studies included observational cohorts and case-control studies. Pooled odds ratios (ORs) and standardized mean differences (SMDs) were calculated using a random-effects model. Heterogeneity was assessed through I2 statistics, and publication bias was evaluated via the Luis Furuya-Kanamori (LFK) index.

Results

15 studies with more than 40,000 participants were analyzed. Significant risk factors for ARDS included pulmonary infection (OR: 2.696, 95 % CI: 1.655 to 4.390), septic shock (OR: 2.627, 95 % CI: 1.850 to 3.731), and pancreatitis (OR: 3.734, 95 % CI: 2.958 to 4.712). No significant associations were found between the development of ARDS in septic patients and the following risk factors: sex (OR: 1.106, 95%CI: 0.957-1.279), smoking status (OR: 1.214, 95%CI: 0.835-1.765), or steroid use (OR: 0.901, 95%CI: 0.617-1.314). APACHE-II and SOFA scores were predictive of ARDS development, emphasizing their utility in clinical assessments.

Conclusion

Pulmonary infection, septic shock, and pancreatitis significantly increase ARDS risk in sepsis patients. Our findings advocate for targeted management of these risk factors to mitigate ARDS development, emphasizing the importance of personalized care in sepsis management.

Hydroxychloroquine attenuates sepsis-induced acute respiratory distress syndrome in rats

BACKGROUND

This study investigates the effects of hydroxychloroquine (HCQ) on a sepsis-induced acute respiratory distress syndrome (ARDS) model in rats, initiated by a fecal intraperitoneal injection procedure (FIP).

METHODS

Three groups were established: control (n=8), FIP + saline (n=7), and FIP + HCQ (20 mg/kg/day) (n=9). Blood samples were collected for arterial blood gas and biochemical analyses, and bilateral pneumonectomy was performed for histopathologic examination.

RESULTS

In the FIP + saline group, PaO2 decreased and PaCO2 increased, whereas these levels normalized in the FIP + HCQ group compared to the control (p<0.001 and p<0.05, respectively). Histopathological scores for alveolar congestion, perivascular/interstitial edema, hemorrhage in alveolar tissue, leukocyte infiltration or aggregation in air spaces/vascular walls, and alveolar wall/hyaline membrane thickness increased in the FIP + saline group compared to the control group (p<0.01). These scores decreased in the FIP + HCQ group compared to the FIP + saline group (p<0.01). HCQ reversed the sepsis-induced increase in malondialdehyde, tumor necrosis factor-alpha, interleukin-6, and lactic acid.

CONCLUSION

HCQ may be an effective and safe option to mitigate the severe progression of ARDS.

Compartmentalization of the inflammatory response during bacterial sepsis and severe COVID-19

Acute infections cause local and systemic disorders which can lead in the most severe forms to multi-organ failure and eventually to death. The host response to infection encompasses a large spectrum of reactions with a concomitant activation of the so-called inflammatory response aimed at fighting the infectious agent and removing damaged tissues or cells, and the anti-inflammatory response aimed at controlling inflammation and initiating the healing process. Fine-tuning at the local and systemic levels is key to preventing local and remote injury due to immune system activation. Thus, during bacterial sepsis and Coronavirus disease 2019 (COVID-19), concomitant systemic and compartmentalized pro-inflammatory and compensatory anti-inflammatory responses are occurring. Immune cells (e.g., macrophages, neutrophils, natural killer cells, and T-lymphocytes), as well as endothelial cells, differ from one compartment to another and contribute to specific organ responses to sterile and microbial insult. Furthermore, tissue-specific microbiota influences the local and systemic response. A better understanding of the tissue-specific immune status, the organ immunity crosstalk, and the role of specific mediators during sepsis and COVID-19 can foster the development of more accurate biomarkers for better diagnosis and prognosis and help to define appropriate host-targeted treatments and vaccines in the context of precision medicine.

Identification and genetic validation of leukemia inhibitory factor super-enhancers in acute respiratory distress syndrome and lung cancer

Super-enhancers play prominent roles in driving robust pathological gene expression, but they are hidden in human genome at noncoding regions, making them difficult to explore. Leukemia inhibitory factor (LIF) is a multifunctional cytokine crucially involved in acute respiratory distress syndrome (ARDS) and lung cancer progression. However, the mechanisms governing LIF regulation in disease contexts remain largely unexplored. In this study, we observed elevated levels of LIF in the bronchoalveolar lavage fluid (BALF) of patients with sepsis-related ARDS compared to those with nonsepsis-related ARDS. Furthermore, both basal and LPS-induced LIF expression were under the control of super-enhancers. Through analysis of H3K27Ac ChIP-seq data, we pinpointed three potential super-enhancers (LIF-SE1, LIF-SE2, and LIF-SE3) located proximal to the LIF gene in cells. Notably, genetic deletion of any of these three super-enhancers using CRISPR-Cas9 technology led to a significant reduction in LIF expression. Moreover, in cells lacking these super-enhancers, both cell growth and invasion capabilities were substantially impaired. Our findings highlight the critical role of three specific super-enhancers in regulating LIF expression and offer new insights into the transcriptional regulation of LIF in ARDS and lung cancer.

Parsimonious Waveform-derived Features consisting of Pulse Arrival Time and Heart Rate Variability Predicts the Onset of Septic Shock

Sepsis is a major public health emergency and one of the leading causes of morbidity and mortality in critically ill patients. For each hour treatment is delayed, shock-related mortality increases, so early diagnosis and intervention is of utmost importance. However, earlier recognition of shock requires active monitoring, which may be delayed due to subclinical manifestations of the disease at the early phase of onset. Machine learning systems can increase timely detection of shock onset by exploiting complex interactions among continuous physiological waveforms. We use a dataset consisting of high-resolution physiological waveforms from intensive care unit (ICU) of a tertiary hospital system. We investigate the use of mean arterial blood pressure (MAP), pulse arrival time (PAT), heart rate variability (HRV), and heart rate (HR) for the early prediction of shock onset. Using only five minutes of the aforementioned vital signals from 239 ICU patients, our developed models can accurately predict septic shock onset 6 to 36 hours prior to clinical recognition with area under the receiver operating characteristic (AUROC) of 0.84 and 0.8 respectively. This work lays foundations for a robust, efficient, accurate and early prediction of septic shock onset which may help clinicians in their decision-making processes. This study introduces machine learning models that provide fast and accurate predictions of septic shock onset times up to 36 hours in advance. BP, PAT and HR dynamics can independently predict septic shock onset with a look-back period of only 5 mins.

Risk factors of acute respiratory distress syndrome in sepsis caused by intra-abdominal infections: A retrospective study

BACKGROUND

Intra-abdominal infections are frequently associated with acute respiratory distress syndrome, which significantly affects patient prognosis. However, little is known about the specific risk factors of acute respiratory distress syndrome in sepsis caused by intra-abdominal infections.

METHODS

This retrospective study included adult patients with intra-abdominal sepsis admitted to the intensive care unit of a tertiary teaching hospital in China between June 2017 and June 2022. Patients were categorized based on the presence or absence of acute respiratory distress syndrome. Data, including vital signs, laboratory values, and severity scores collected within 24 hours of sepsis diagnosis, as well as outcomes within 90 days, were analyzed. Multivariable logistic regression was used to identify independent risk factors associated with acute respiratory distress syndrome.

RESULTS

A total of 738 patients were included, of whom 218 (29.5%) developed acute respiratory distress syndrome. Patients with acute respiratory distress syndrome were younger, had a higher body mass index and disease severity scores, and exhibited higher proportions of septic shock and hospital-acquired intra-abdominal infections. The mortalities in the intensive care unit and at 28 and 90 days were higher in the acute respiratory distress syndrome group. In the multivariate logistic regression model, age under 65 years (odds ratio [95% confidence interval]: 1.571 [1.093-2.259]), elevated body mass index (2.070 [1.382-3.101] for overweight, 6.994 [3.207-15.255]) for obesity, septic shock (2.043 [1.400-2.980]), procalcitonin (1.009 [1.004-1.015]), hospital-acquired intra-abdominal infections (2.528[1.373-4.657]), and source of intra-abdominal infections (2.170 [1.140-4.128] for biliary tract infection, 0.443 [0.217-0.904] for gastroduodenal perforation) were independently associated with acute respiratory distress syndrome.

CONCLUSION

In patients with intra-abdominal sepsis, age under 65 years, higher body mass index and procalcitonin, septic shock, hospital-acquired intra-abdominal infections, and biliary tract infection were risk factors for acute respiratory distress syndrome.

Lung tissue expression of epithelial injury markers is associated with acute lung injury severity but does not discriminate sepsis from ARDS

BACKGROUND

Acute respiratory distress syndrome (ARDS) is a common cause of respiratory failure in critically ill patients, and diffuse alveolar damage (DAD) is considered its histological hallmark. Sepsis is one of the most common aetiology of ARDS with the highest case-fatality rate. Identifying ARDS patients and differentiate them from other causes of acute respiratory failure remains a challenge. To address this, many studies have focused on identifying biomarkers that can help assess lung epithelial injury. However, there is scarce information available regarding the tissue expression of these markers. Evaluating the expression of elafin, RAGE, and SP-D in lung tissue offers a potential bridge between serological markers and the underlying histopathological changes. Therefore, we hypothesize that the expression of epithelial injury markers varies between sepsis and ARDS as well as according to its severity.

METHODS

We compared the post-mortem lung tissue expression of the epithelial injury markers RAGE, SP-D, and elafin of patients that died of sepsis, ARDS, and controls that died from non-pulmonary causes. Lung tissue was collected during routine autopsy and protein expression was assessed by immunohistochemistry. We also assessed the lung injury by a semi-quantitative analysis.

RESULTS

We observed that all features of DAD were milder in septic group compared to ARDS group. Elafin tissue expression was increased and SP-D was decreased in the sepsis and ARDS groups. Severe ARDS expressed higher levels of elafin and RAGE, and they were negatively correlated with PaO2/FiO2 ratio, and positively correlated with bronchopneumonia percentage and hyaline membrane score. RAGE tissue expression was negatively correlated with mechanical ventilation duration in both ARDS and septic groups. In septic patients, elafin was positively correlated with ICU admission length, SP-D was positively correlated with serum lactate and RAGE was correlated with C-reactive protein.

CONCLUSIONS

Lung tissue expression of elafin and RAGE, but not SP-D, is associated with ARDS severity, but does not discriminate sepsis patients from ARDS patients.

Post-operative sepsis-induced acute respiratory distress syndrome: risk factors for a life-threatening complication

Introduction

Prevalence and mortality of the acute respiratory distress syndrome (ARDS) in intensive care units (ICU) are unacceptably high. There is scarce literature on post-operative sepsis-induced ARDS despite that sepsis and major surgery are conditions associated with ARDS. We aimed to examine the impact of post-operative sepsis-induced ARDS on 60-day mortality.

Methods

We performed a secondary analysis of a prospective observational study in 454 patients who underwent major surgery admitted into a single ICU. Patients were stratified in two groups depending on whether they met criteria for ARDS. Primary outcome was 60-day mortality of post-operative sepsis-induced ARDS. Secondary outcome measures were potential risk factors for post-operative sepsis-induced ARDS, and for 60-day mortality.

Results

Higher SOFA score (OR 1.1, 95% CI 1.0-1.3, p = 0.020) and higher lactate (OR 1.9, 95% CI 1.2-2.7, p = 0.004) at study inclusion were independently associated with ARDS. ARDS patients (n = 45) had higher ICU stay [14 (18) vs. 5 (11) days, p < 0.001] and longer need for mechanical ventilation [6 (14) vs. 1 (5) days, p < 0.001] than non-ARDS patients (n = 409). Sixty-day mortality was higher in ARDS patients (OR 2.7, 95% CI 1.1-6.3, p = 0.024). Chronic renal failure (OR 4.0, 95% CI 1.2-13.7, p = 0.026), elevated lactate dehydrogenase (OR 1.7, 95% CI 1.1-2.7, p = 0.015) and higher APACHE II score (OR 2.7, 95% CI 1.3-5.4, p = 0.006) were independently associated with 60-day mortality.

Conclusion

Post-operative sepsis-induced ARDS is associated with higher 60-day mortality compared to non-ARDS post-operative septic patients. Post-operative septic patients with higher severity of illness have a greater risk of ARDS and worse outcomes. Further investigation is needed in post-operative sepsis-induced ARDS to prevent ARDS.

The Effect of Galantamine on Lipopolysaccharide-induced Acute Lung Injury During Neutropenia Recovery in Mice

BACKGROUND/AIM

Acute lung injury (ALI) is associated with a high mortality rate and cancer patients who receive chemotherapy are at high risk of ALI during neutropenia recovery. Galantamine is a cholinesterase inhibitor used for Alzheimer's disease treatment. Previous studies have shown that galantamine reduced inflammatory response in lipopolysaccharide (LPS)-induced ALI in rats. Mer protein was negatively associated with inflammatory response. The aim of the study was to investigate whether galantamine is effective in LPS-induced ALI during neutropenia recovery and its effect on Mer tyrosine kinase (MerTK) expression in mice.

MATERIALS AND METHODS

Intraperitoneal cyclophosphamide was given to mice to induce neutropenia. After 7 days, LPS was administered by intratracheal instillation. Intraperitoneal galantamine was given once before LPS administration and in another group, galantamine was given twice before LPS administration.

RESULTS

Galantamine attenuated LPS-induced ALI in histopathological analysis. The neutrophil percentage was lower in the group where galantamine was injected once, compared to the LPS group (p=0.007). MerTK expression was also higher in the group where galantamine was injected once but did not reach statistical significance (p=0.101).

CONCLUSION

Galantamine attenuated inflammation in LPS-induced ALI during neutropenia recovery.

Effect of a physician-nurse integrated lung protection care model in neurocritical patients

Background

Lung injury resulting from diffuse pulmonary interstitial and other lung-related complications is a significant contributor to poor prognosis and mortality in patients with critical neurological diseases. To enhance patient outcomes, it is essential to investigate a lung protection model that involves the collaboration of doctors, nurses, and other medical professionals.

Methods

Patients receiving different care styles were divided into two groups: routine care (RC) and lung function protection care (LFPC). The LFPC group included airway and posture management, sedation and analgesia management, positive end-expiratory pressure titration in ventilation management, and fluid volume management, among others. Statistical analysis methods, such as chi-square, were used to compare the incidence of acute lung injury (ALI), neurogenic pulmonary edema (NPE), ventilator-associated pneumonia (VAP), acute respiratory distress syndrome (ARDS), and length of stay between the RC and LFPC groups.

Results

The RC group included 68 patients (33 males; 34-74 years of age). The LFPC group included 60 patients (29 males; 37-73 years of age). Compared with the RC group, the LFPC group had lower occurrence rates of ALI (20.0 % vs. 38.2 %, P = 0.024), NPE (8.3 % vs. 23.5 %, P = 0.021), VAP (8.3 % vs. 25.0 %, P = 0.013), and ARDS (1.7 % vs. 16.2 %, P = 0.015). The length of hospital stay was shorter in the LFPC group than in the RC group (11.3 ± 3.5 vs. 14.3 ± 4.4 days, P = 0.0001).

Conclusion

The physician-nurse integrated lung protection care model proved to be effective in improving outcomes, reducing complications, and shortening the hospital stay length for neurocritical patients.

Global Scientific Trends in Continuous Renal Replacement Therapy from 2000 to 2023: A Bibliometric and Visual Analysis

INTRODUCTION

Continuous renal replacement therapy (CRRT) is one of the most widely used blood purification and organ support methods in the ICU. However, the development process, the current status, hotspots, and future trends of CRRT remain unclear.

METHOD

The WoSCC database was used to analyze CRRT research evolution and theme trends. VOSviewer was used to construct coauthorship, co-occurrence, co-citation, and network visualizations. CiteSpace is used to detect bursts for co-occurrence items. Several important subtopics were reviewed and discussed in more detail.

RESULTS

Global publications increased from 56 in 2000 to 398 in 2023, a 710.71% increase. Blood Purification published the most manuscripts, followed by the International Journal of Artificial Organs. The USA, the San Bortolo Hospital, and Bellomo were the most productive and impactful institution, country, and author, respectively. Based on co-occurrence cluster analysis, five clusters emerged: (1) clinical applications and management of CRRT; (2) sepsis and CRRT; (3) CRRT anticoagulant management; (4) CRRT and antibiotic pharmacokinetics and pharmacodynamics; and (5) comparison of CRRT and intermittent hemodialysis. COVID-19, initiation, ECOMO, cefepime, guidelines, cardiogenic shock, biomarker, and outcome were the latest high-frequency keywords or strongest bursts, indicating the emerging frontiers of CRRT.

CONCLUSIONS

There has been widespread publication and citation of CRRT research in the past 2 decades. We provide an overview of current trends, global collaboration patterns, basic knowledge, research hotspots, and emerging frontiers.

TRENDS IN CHOLESTEROL AND LIPOPROTEINS ARE ASSOCIATED WITH ACUTE RESPIRATORY DISTRESS SYNDROME INCIDENCE AND DEATH AMONG SEPSIS PATIENTS

ABSTRACT

Objective: Compare changes in cholesterol and lipoprotein levels occurring in septic patients with and without acute respiratory distress syndrome (ARDS) and by survivorship. Methods: We reanalyzed data from prospective sepsis studies. Cholesterol and lipoprotein levels were analyzed using univariate testing to detect changes between septic patients with or without ARDS, and among ARDS survivors compared with nonsurvivors at enrollment (first 24 h of sepsis) and 48 to 72 h later. Results: 214 patients with sepsis were included of whom 48 had ARDS and 166 did not have ARDS. Cholesterol and lipoproteins among septic ARDS versus non-ARDS showed similar enrollment levels. However, 48 to 72 h after enrollment, change in median total cholesterol (48/72 h - enrollment) was significantly different between septic ARDS (-4, interquartile range [IQR] -23.5, 6.5, n = 35) and non-ARDS (0, -10.0, 17.5, P = 0.04; n = 106). When compared by ARDS survivorship, ARDS nonsurvivors (n = 14) had lower median total cholesterol levels (75.5, IQR 68.4, 93.5) compared with ARDS survivors (113.0, IQR 84.0, 126.8, P = 0.022), and lower median enrollment low-density lipoprotein cholesterol (LDL-C) levels (27, IQR 19.5-34.5) compared with ARDS survivors (43, IQR 27-67, P = 0.013; n = 33). Apolipoprotein A-I levels were also significantly lower in ARDS nonsurvivors (n = 14) (87.6, IQR 76.45-103.64) compared with ARDS survivors (130.0, IQR 73.25-165.47, P = 0.047; n = 33). At 48 to 72 h, for ARDS nonsurvivors, median levels of low-density lipoprotein cholesterol (9.0, IQR 4.3, 18.0; n = 10), LDL-C (17.0, IQR 5.0, 29.0; n = 9), and total cholesterol (59.0, 45.3, 81.5; n = 10) were significantly lower compared with ARDS survivors' (n = 25) levels of low-density lipoprotein cholesterol (20.0, IQR 12.0-39.0, P = 0.014), LDL-C (42.0, IQR 27.0-58.0, P = 0.019), and total cholesterol (105.0, IQR 91.0, 115.0, P = 0.003). Conclusions: Change in total cholesterol was different in septic ARDS versus non-ARDS. Total cholesterol, LDL-C, and apolipoprotein A-I levels were lower in ARDS nonsurvivors compared with survivors. Future studies of dysregulated cholesterol metabolism in septic ARDS patients are needed to understand biology and links to potential therapies.

COAGULOPATHY PARAMETERS PREDICTIVE OF OUTCOMES IN SEPSIS-INDUCED ACUTE RESPIRATORY DISTRESS SYNDROME: A SUBANALYSIS OF THE TWO PROSPECTIVE MULTICENTER COHORT STUDIES

ABSTRACT

Background: Although coagulopathy is often observed in acute respiratory distress syndrome (ARDS), its clinical impact remains poorly understood. Objectives: This study aimed to clarify the coagulopathy parameters that are clinically applicable for prognostication and to determine anticoagulant indications in sepsis-induced ARDS. Method: This study enrolled patients with sepsis-derived ARDS from two nationwide multicenter, prospective observational studies. We explored coagulopathy parameters that could predict outcomes in the Focused Outcome Research on Emergency Care for Acute Respiratory Distress Syndrome, Sepsis, and Trauma (FORECAST) cohort, and the defined coagulopathy criteria were validated in the Sepsis Prognostication in Intensive Care Unit and Emergency Room-Intensive Care Unit (SPICE-ICU) cohort. The correlation between anticoagulant use and outcomes was also evaluated. Results: A total of 181 patients with sepsis-derived ARDS in the FORECAST study and 61 patients in the SPICE-ICU study were included. In a preliminary study, we found the set of prothrombin time-international normalized ratio ≥1.4 and platelet count ≤12 × 10 4 /μL, and thrombocytopenia and elongated prothrombin time (TEP) coagulopathy as the best coagulopathy parameters and used it for further analysis; the odds ratio (OR) of TEP coagulopathy for in-hospital mortality adjusted for confounding was 3.84 (95% confidence interval [CI], 1.66-8.87; P = 0.005). In the validation cohort, the adjusted OR for in-hospital mortality was 32.99 (95% CI, 2.60-418.72; P = 0.002). Although patients without TEP coagulopathy showed significant improvements in oxygenation over the first 4 days, patients with TEP coagulopathy showed no significant improvement (ΔPaO 2 /FiO 2 ratio, 24 ± 20 vs. 90 ± 9; P = 0.026). Furthermore, anticoagulant use was significantly correlated with mortality and oxygenation recovery in patients with TEP coagulopathy but not in patients without TEP coagulopathy. Conclusion: Thrombocytopenia and elongated prothrombin time coagulopathy is closely associated with better outcomes and responses to anticoagulant therapy in sepsis-induced ARDS, and our coagulopathy criteria may be clinically useful.

ADAR1 protects pulmonary macrophages from sepsis-induced pyroptosis and lung injury through miR-21/A20 signaling

Acute lung injury is a serious complication of sepsis with high morbidity and mortality. Pyroptosis is a proinflammatory form of programmed cell death that leads to immune dysregulation and organ dysfunction during sepsis. We previously found that adenosine deaminase acting on double-stranded RNA 1 (ADAR1) plays regulatory roles in the pathology of sepsis, but the mechanism of ADAR1 in sepsis-induced pyroptosis and lung injury remains unclear. Here, we mainly investigated the regulatory effects and underlying mechanism of ADAR1 in sepsis-induced lung injury and pyroptosis of pulmonary macrophages through RNA sequencing of clinical samples, caecal ligation and puncture (CLP)-induced septic mouse models, and in vitro cellular experiments using RAW264.7 cells with lipopolysaccharide (LPS) stimulation. The results showed that pyroptosis was activated in peripheral blood mononuclear cells (PBMCs) from patients with sepsis. In the CLP-induced septic mouse model, pyroptosis was mainly activated in pulmonary macrophages. LPS-stimulated RAW264.7 cells showed significantly increased activation of the NLRP3 inflammasome. ADAR1 was downregulated in PMBCs of patients with sepsis, and overexpression of ADAR1 alleviated CLP-induced lung injury and NLRP3 inflammasome activation. Mechanistically, the regulatory effects of ADAR1 on macrophage pyroptosis were mediated by the miR-21/A20/NLRP3 signalling cascade. ADAR1 attenuated sepsis-induced lung injury and hindered the activation of pyroptosis in pulmonary macrophages in sepsis through the miR-21/A20/NLRP3 axis. Our study highlights the role of ADAR1 in protecting pulmonary macrophages against pyroptosis and suggests targeting ADAR1/miR-21 signalling as a therapeutic opportunity in sepsis-related lung injury.

Acute respiratory distress syndrome heterogeneity and the septic ARDS subgroup

Acute respiratory distress syndrome (ARDS) is an acute diffuse inflammatory lung injury characterized by the damage of alveolar epithelial cells and pulmonary capillary endothelial cells. It is mainly manifested by non-cardiogenic pulmonary edema, resulting from intrapulmonary and extrapulmonary risk factors. ARDS is often accompanied by immune system disturbance, both locally in the lungs and systemically. As a common heterogeneous disease in critical care medicine, researchers are often faced with the failure of clinical trials. Latent class analysis had been used to compensate for poor outcomes and found that targeted treatment after subgrouping contribute to ARDS therapy. The subphenotype of ARDS caused by sepsis has garnered attention due to its refractory nature and detrimental consequences. Sepsis stands as the most predominant extrapulmonary cause of ARDS, accounting for approximately 32% of ARDS cases. Studies indicate that sepsis-induced ARDS tends to be more severe than ARDS caused by other factors, leading to poorer prognosis and higher mortality rate. This comprehensive review delves into the immunological mechanisms of sepsis-ARDS, the heterogeneity of ARDS and existing research on targeted treatments, aiming to providing mechanism understanding and exploring ideas for accurate treatment of ARDS or sepsis-ARDS.

Global prevalence of COVID-19-induced acute respiratory distress syndrome: systematic review and meta-analysis

BACKGROUND

Acute respiratory distress syndrome (ARDS) is potentially a fatal form of respiratory failure among COVID-19 patients. Globally, there are inconsistent findings regarding ARDS among COVID-19 patients. Therefore, this study aimed to estimate the pooled prevalence of COVID-19-induced ARDS among COVID-19 patients worldwide.

METHODS

To retrieve relevant studies, the authors searched Embase, MEDLINE, PubMed, Web of Science, Cochrane Library, Google, and Google Scholar using a combination of search terms. The search was conducted for articles published from December 2019 to September 2022. Articles were searched and screened by title (ti), abstract (ab), and full-text (ft) by two reviewers independently. The quality of each included article was assessed using the Newcastle-Ottawa Assessment Scale. Data were entered into Microsoft Word and exported to Stata version 14 for analysis. Heterogeneity was detected using the Cochrane Q statistics and I-square (I2). Then the sources of variations were identified by subgroup and meta-regression analysis. A random effect meta-analysis model was used. The publication bias was detected using the graphic asymmetry test of the funnel plot and/or Egger's test (p value < 0.05). To treat the potential publication bias, trim and fill analysis were computed. The protocol has been registered in an international database, the Prospective Register of Systematic Reviews (PROSPERO) with reference number: CRD42023438277.

RESULTS

A total of 794 studies worldwide were screened for their eligibility. Of these 11 studies with 2845 participants were included in this systematic review and meta-analysis. The overall pooled prevalence of COVID-19-induced ARDS in the world was found to be 32.2% (95%CI = 27.70-41.73%), I2 = 97.3%, and p value < 0.001).

CONCLUSION

The pooled prevalence of COVID-19-induced ARDS was found to be high. The virus remains a global burden because its genetic causes are constantly changing or it mutated throughout the pandemic to emerge a new strain of infection. Therefore, interventions such as massive vaccination, early case detection, screening, isolation, and treatment of the cases need to be implemented to tackle its severity.

Establishment and validation of a predictive model for respiratory failure within 48 h following admission in patients with sepsis: a retrospective cohort study

Objective: The objective of this study is to identify patients with sepsis who are at a high risk of respiratory failure. Methods: Data of 1,738 patients with sepsis admitted to Dongyang People's Hospital from June 2013 to May 2023 were collected, including the age at admission, blood indicators, and physiological indicators. Independent risk factors for respiratory failure during hospitalization in the modeling population were analyzed to establish a nomogram. The area under the receiver operating characteristic curve (AUC) was used to evaluate the discriminative ability, the GiViTI calibration graph was used to evaluate the calibration, and the decline curve analysis (DCA) curve was used to evaluate and predict the clinical validity. The model was compared with the Sequential Organ Failure Assessment (SOFA) score, the National Early Warning Score (NEWS) system, and the ensemble model using the validation population. Results: Ten independent risk factors for respiratory failure in patients with sepsis were included in the final logistic model. The AUC values of the prediction model in the modeling population and validation population were 0.792 and 0.807, respectively, both with good fit between the predicted possibility and the observed event. The DCA curves were far away from the two extreme curves, indicating good clinical benefits. Based on the AUC values in the validation population, this model showed higher discrimination power than the SOFA score (AUC: 0.682; p < 0.001) and NEWS (AUC: 0.520; p < 0.001), and it was comparable to the ensemble model (AUC: 0.758; p = 0.180). Conclusion: Our model had good performance in predicting the risk of respiratory failure in patients with sepsis within 48 h following admission.

Effects of intravenous sivelestat sodium on prevention of acute respiratory distress syndrome in patients with sepsis: study protocol for a double-blind multicentre randomised controlled trial

INTRODUCTION

Sepsis is one of the most common risk factors for acute respiratory distress syndrome (ARDS). Neutrophil elastase (NE) is believed to be an important mediator of ARDS. When sepsis occurs, a large number of inflammatory factors are activated and released, which makes neutrophils migrate into the lung, eventually leading to the occurrence of ARDS. Sivelestat sodium is an NE inhibitor that can inhibit the inflammatory reaction during systemic inflammatory response syndrome and alleviate lung injury. Therefore, we hypothesise that intravenous sivelestat sodium may prevent the occurrence of ARDS in patients with sepsis.

METHODS AND ANALYSIS

This is a prospective, investigator-initiated, double-blind, adaptive, multicentre, randomised, controlled clinical trial with an adaptive 'sample size re-estimation' design. Patients meeting the inclusion criteria who were transferred into the intensive care unit will be randomly assigned to receive sivelestat sodium or placebo for up to 7 days. The primary outcome is the development of ARDS within 7 days after randomisation. A total of 238 patients will be recruited based on a 15% decrease in the incidence of ARDS in the intervention group in this study. A predefined interim analysis will be performed to ensure that the calculation is reasonable after reaching 50% (120) of the planned sample size.

ETHICS AND DISSEMINATION

The study protocol was approved by the Ethics Committee of ZhongDa Hospital affiliated to Southeast University (identifier: Clinical Ethical Approval No. 2021ZDSYLL153-P03). Results will be submitted for publication in peer-reviewed journals and presented at relevant conferences and meetings.

TRIAL REGISTRATION NUMBER

NCT04973670.

Investigating the link between miR-34a-5p and TLR6 signaling in sepsis-induced ARDS

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) are lung complications diagnosed by impaired gaseous exchanges leading to mortality. From the diverse etiologies, sepsis is a prominent contributor to ALI/ARDS. In the present study, we retrieved sepsis-induced ARDS mRNA expression profile and identified 883 differentially expressed genes (DEGs). Next, we established an ARDS-specific weighted gene co-expression network (WGCN) and picked the blue module as our hub module based on highly correlated network properties. Later we subjected all hub module DEGs to form an ARDS-specific 3-node feed-forward loop (FFL) whose highest-order subnetwork motif revealed one TF (STAT6), one miRNA (miR-34a-5p), and one mRNA (TLR6). Thereafter, we screened a natural product library and identified three lead molecules that showed promising binding affinity against TLR6. We then performed molecular dynamics simulations to evaluate the stability and binding free energy of the TLR6-lead molecule complexes. Our results suggest these lead molecules may be potential therapeutic candidates for treating sepsis-induced ALI/ARDS. In-silico studies on clinical datasets for sepsis-induced ARDS indicate a possible positive interaction between miR-34a and TLR6 and an antagonizing effect on STAT6 to promote inflammation. Also, the translational study on septic mice lungs by IHC staining reveals a hike in the expression of TLR6. We report here that miR-34a actively augments the effect of sepsis on lung epithelial cell apoptosis. This study suggests that miR-34a promotes TLR6 to heighten inflammation in sepsis-induced ALI/ARDS.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03700-1.

RIGHT VENTRICULAR DYSFUNCTION IN SEPSIS: AN UPDATED NARRATIVE REVIEW

ABSTRACT

Sepsis is a multisystem disease process, which constitutes a significant public health challenge and is associated with high morbidity and mortality. Among other systems, sepsis is known to affect the cardiovascular system, which may manifest as myocardial injury, arrhythmias, refractory shock, and/or septic cardiomyopathy. Septic cardiomyopathy is defined as the reversible systolic and/or diastolic dysfunction of one or both ventricles. Left ventricle dysfunction has been extensively studied in the past, and its prognostic role in patients with sepsis is well documented. However, there is relatively scarce literature on right ventricle (RV) dysfunction and its role. Given the importance of timely detection of septic cardiomyopathy and its bearing on prognosis of patients, the role of RV dysfunction has come into renewed focus. Hence, through this review, we sought to describe the pathophysiology of RV dysfunction in sepsis and what have we learnt so far about its multifactorial nature. We also elucidate the roles of different biomarkers for its detection and prognosis, along with appropriate management of such patient population.

Single-cell analysis reveals dysregulated inflammatory response in peripheral blood immunity in patients with acute respiratory distress syndrome

Introduction: Acute respiratory distress syndrome (ARDS) remains a major clinical challenge for patients in intensive care units. Determining the differential mechanisms underlying ARDS with different etiologies is a key goal to improve the effectiveness of ARDS therapy. Despite growing evidence that different immune cell types are involved in ARDS, the role of altered immune cell subpopulations in disease progression is unelucidated. Methods: In this study, we combined scRNA-seq and bulk-level sequencing to analyze the transcriptomes of peripheral blood mononuclear cells from healthy volunteers and patients with septic ARDS (sep-ARDS) and pneumonic ARDS (PNE-ARDS). Results: Our data revealed differential alterations at the cellular and molecular levels and within biological signaling pathways in ARDS with different etiologies. The dynamics of neutrophils, macrophages (Macs), classical dendritic cells (cDCs), myeloid-derived suppressive cells (MDSCs), and CD8⁺ T cells varied significantly among groups of different samples, with neutrophils and cDCs at higher, and Macs at significantly lower, amounts in the patients with sep-ARDS. Furthermore, MDSCs were highly enriched only in the sep-ARDS patients, whereas a higher abundance of CD8⁺ T cells was observed in patients with PNE-ARDS. In addition, these cell subpopulations were found to be significantly involved in apoptosis, inflammatory, and immune-related pathways. In particular, a significant enhancement of the oxidative stress response was observed in the neutrophil subpopulation. Conclusion: Our study shows that the composition of cells involved in the main peripheral circulation differs in patients with ARDS with different etiologies. Studying the role and mechanism of action of these cells during ARDS will provide new opportunities for the treatment of this condition.

Corticosteroids in ARDS

Acute respiratory distress syndrome (ARDS) is frequently associated with sepsis. ARDS and sepsis exhibit a common pathobiology, namely excessive inflammation. Corticosteroids are powerful anti-inflammatory agents that are routinely used in septic shock and in oxygen-dependent SARS-CoV-2 related acute respiratory failure. Recently, corticosteroids were found to reduce mortality in severe community-acquired pneumonia. Corticosteroids may therefore also have a role to play in the treatment of ARDS. This narrative review was undertaken following a PubMed search for English language reports published before January 2023 using the terms acute respiratory distress syndrome, sepsis and steroids. Additional reports were identified by examining the reference lists of selected articles and based on personnel knowledge of the authors of the field. High-quality research is needed to fully understand the role of corticosteroids in the treatment of ARDS and to determine the optimal timing, dosing and duration of treatment.

Clinical outcomes after a single induction dose of etomidate versus ketamine for emergency department sepsis intubation: a randomized controlled trial

Patients with sepsis often require emergency intubation. In emergency departments (EDs), rapid-sequence intubation with a single-dose induction agent is standard practice, but the best choice of induction agent in sepsis remains controversial. We conducted a randomized, controlled, single-blind trial in the ED. We included septic patients who were aged at least 18 years and required sedation for emergency intubation. Patients were randomly assigned by a blocked randomization to receive 0.2-0.3 mg/kg of etomidate or 1-2 mg/kg of ketamine for intubation. The objectives were to compare the survival outcomes and adverse events after intubation between etomidate and ketamine. Two hundred and sixty septic patients were enrolled; 130 patients/drug arm whose baseline characteristics were well balanced at baseline. In the etomidate group, 105 patients (80.8%) were alive at 28 days, compared with 95 patients (73.1%) in the ketamine group (risk difference [RD], 7.7%; 95% confidence interval [CI], - 2.5 to 17.9%; P = 0.092). There was no significant difference in the proportion of patients who survived at 24 h (91.5% vs. 96.2%; P = 0.097) and survived at 7 days (87.7% vs. 87.7%; P = 0.574). A significantly higher proportion of the etomidate group needed a vasopressor within 24 h after intubation: 43.9% vs. 17.7%, RD, 26.2% (95% CI, 15.4 to 36.9%; P < 0.001). In conclusion, there were no differences in early and late survival rates between etomidate and ketamine. However, etomidate was associated with higher risks of early vasopressor use after intubation. Trial registration: The trial protocol was registered in the Thai Clinical Trials Registry (identification number: TCTR20210213001). Registered 13 February 2021-Retrospectively registered, https://www.thaiclinicaltrials.org/export/pdf/TCTR20210213001 .

A Systematic Review and Meta-Analysis of Independent Predictors for Acute Respiratory Distress Syndrome in Patients Presenting With Sepsis

The current meta-analysis was conducted to determine the predictors of acute respiratory distress syndrome (ARDS) in patients with sepsis. The present meta-analysis was conducted in accordance with the MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines. We conducted a systematic search using the PubMed, Cochrane Library, and EMBASE databases for studies published between 1 January 2000 and 28 February 2023 that assessed the predictors of ARDS in patients with sepsis. We used key terms such as "predictors," "acute respiratory distress syndrome," and "sepsis" to search for relevant articles. Our search was limited to human studies published in English. A total of six studies were included in this meta-analysis. Of the six studies, four were retrospective and two were prospective. The pooled incidence of ARDS was 11.27%. We identified six factors with a consistent and statistically significant association with ARDS, including sequential organ failure assessment (SOFA) score, Acute Physiology and Chronic Health Evaluation (APACHE) II score, pulmonary sepsis, smoking, pancreatitis, and C-reactive protein. Age, diabetes, and chronic obstructive pulmonary disease (COPD) were not found to be significantly associated with ARDS in this patient population. It is important for healthcare providers to consider these predictors when assessing patients with sepsis and septic shock to identify those at high risk for developing ARDS and implement appropriate preventive measures.

Altered Lung Heat Shock Protein-70 Expression and Severity of Sepsis-Induced Acute Lung Injury in a Chronic Kidney Disease Rat Model

Enhanced heat shock protein-70 (HSP-70) expression in the lungs is associated with attenuated acute lung injury (ALI) in a sepsis model. Chronic kidney disease (CKD) significantly contributes to the poor prognosis of patients with sepsis. This study examined the relationship between sepsis-induced ALI severity and altered lung HSP-70 expression in CKD. Experimental rats underwent a sham operation (control group) or 5/6 nephrectomy (CKD group). Sepsis was induced with cecal ligation and puncture (CLP). Laboratory tests and lung harvest were performed in the control group (without CLP and after 3, 12, 24, and 72 h of CLP) and in the CKD group (without CLP and after 72 h of CLP). ALI was the most severe after 12 h of sepsis. The mean lung injury score at 72 h after sepsis was significantly higher in the CKD group than in the control group (4.38 versus 3.30, p < 0.01). Nonetheless, enhanced lung HSP-70 expression was not observed in the CKD group. This study shows that altered lung HSP-70 expression is associated with the worsening of sepsis-induced ALI in patients with CKD. Enhancing lung HSP-70 is a novel treatment target for patients with CKD and sepsis-induced ALI.

A prediction model for predicting the risk of acute respiratory distress syndrome in sepsis patients: a retrospective cohort study

BACKGROUND

The risk of death in sepsis patients with acute respiratory distress syndrome (ARDS) was as high as 20-50%. Few studies focused on the risk identification of ARDS among sepsis patients. This study aimed to develop and validate a nomogram to predict the ARDS risk in sepsis patients based on the Medical Information Mart for Intensive Care IV database.

METHODS

A total of 16,523 sepsis patients were included and randomly divided into the training and testing sets with a ratio of 7:3 in this retrospective cohort study. The outcomes were defined as the occurrence of ARDS for ICU patients with sepsis. Univariate and multivariate logistic regression analyses were used in the training set to identify the factors that were associated with ARDS risk, which were adopted to establish the nomogram. The receiver operating characteristic and calibration curves were used to assess the predictive performance of nomogram.

RESULTS

Totally 2422 (20.66%) sepsis patients occurred ARDS, with the median follow-up time of 8.47 (5.20, 16.20) days. The results found that body mass index, respiratory rate, urine output, partial pressure of carbon dioxide, blood urea nitrogen, vasopressin, continuous renal replacement therapy, ventilation status, chronic pulmonary disease, malignant cancer, liver disease, septic shock and pancreatitis might be predictors. The area under the curve of developed model were 0.811 (95% CI 0.802-0.820) in the training set and 0.812 (95% CI 0.798-0.826) in the testing set. The calibration curve showed a good concordance between the predicted and observed ARDS among sepsis patients.

CONCLUSION

We developed a model incorporating thirteen clinical features to predict the ARDS risk in patients with sepsis. The model showed a good predictive ability by internal validation.

Predicting Persistent Acute Respiratory Failure in Acute Pancreatitis: The Accuracy of Two Lung Injury Indices

BACKGROUND/AIMS

Early and accurate identification of patients with acute pancreatitis (AP) at high risk of persistent acute respiratory failure (PARF) is crucial. We sought to determine the accuracy of simplified Lung Injury Prediction Score (sLIPS) and simplified Early Acute Lung Injury (sEALI) for predicting PARF in ward AP patients.

METHODS

Consecutive AP patients in a training cohort from West China Hospital of Sichuan University (n = 912) and a validation cohort from The First Affiliated Hospital of Nanchang University (n = 1033) were analyzed. PARF was defined as oxygen in arterial blood/fraction of inspired oxygen < 300 mmHg that lasts for > 48 h. The sLIPS was composed by shock (predisposing condition), alcohol abuse, obesity, high respiratory rate, low oxygen saturation, high oxygen requirement, hypoalbuminemia, and acidosis (risk modifiers). The sEALI was calculated from oxygen 2 to 6 L/min, oxygen > 6 L/min, and high respiratory rate. Both indices were calculated on admission.

RESULTS

PARF developed in 16% (145/912) and 22% (228/1033) (22%) of the training and validation cohorts, respectively. In these patients, sLIPS and sEALI were significantly increased. sLIPS ≥ 2 predicted PARF in the training (AUROC 0.87, 95% CI 0.84-0.89) and validation (AUROC 0.81, 95% CI 0.78-0.83) cohorts. sLIPS was significantly more accurate than sEALI and current clinical scoring systems in both cohorts (all P < 0.05).

CONCLUSIONS

Using routinely available clinical data, the sLIPS can accurately predict PARF in ward AP patients and outperforms the sEALI and current existing clinical scoring systems.

Prognostic implication of a novel right ventricular injury score in septic patients

AIMS

We aim to investigate the prognostic value of a right ventricular (RV) injury score based on the concept of RV dilation, RV systolic dysfunction, and RV-pulmonary arterial (PA) decoupling in septic patients and to explore whether the RV injury (RVI) score can be used to grade the severity of RV dysfunction in these patients.

METHODS AND RESULTS

Septic patients admitted to the ICU were prospectively included. We collected haemodynamic and echocardiographic parameters as well as prognostic information. RV dilation was defined as right and left ventricular end-diastolic area ratio (R/LVEDA) > 2/3. RVSD was defined as tricuspid annular plane systolic excursion (TAPSE) < 17 mm, right ventricular fractional area change (FAC) < 35%, or peak velocity of tricuspid annulus via tissue Doppler (S') < 10 cm/s. RV-PA decoupling was represented by the TAPSE/pulmonary arterial systolic pressure (PASP) ratio. RVI score were determined by the presence of the following findings: RVSD, RV dilation, and RV-PA decoupling, that is, one point for each finding. A total of 327 patients were enrolled in this study, among whom 276 survived and 51 died at 30 days after admission. Overall, 18.0% had RV dilation, 35.8% had RVSD, and 21.4% had RV-PA decoupling, with an appreciable overlap present. A multivariate Cox regression analysis showed that RV dilation (HR: 2.19, 95% CI: 1.19-4.01, P = 0.011), RVSD (HR: 2.25, 95% CI: 1.23-4.13, P = 0.009) and RV-PA decoupling (HR: 2.08, 95% CI: 1.19-3.65, P = 0.011) were independently associated with a 30 day mortality. Furthermore, RVI score was also an independent predictor, displayed additive effect with respect to 30 day mortality (RVI score 1 vs. RVI score 0, HR: 2.94, 95% CI: 1.20-7.20, P = 0.018; RVI score 2 vs. RVI score 0, HR: 3.20, 95% CI: 1.28-7.98, P = 0.013; RVI score 3 vs. RVI score 0, HR: 7.17, 95% CI: 2.65-19.38, P < 0.001), and had the best performance in model goodness of fit, discrimination and variance explained than the other RV indices.

CONCLUSIONS

The RVI score was independently related to 30 day mortality and had the potential to grade the severity of RV dysfunction in septic patients.

PLD2 deletion alleviates disruption of tight junctions in sepsis-induced ALI by regulating PA/STAT3 phosphorylation pathway

BACKGROUND

Increased inflammatory exudation caused by endothelium and endothelial junction damage is a typical pathological feature of acute respiratory distress syndrome/acute lung injury (ARDS/ALI). Previous studies have shown that phospholipase D2 (PLD2) can increase the inflammatory response and has a close relationship with the severity of sepsis-induced ALI and the mortality of sepsis, but its mechanism is unknown. This study explored the effect and mechanism of PLD2 deletion on the structure and function of endothelial tight junction (TJ) in lipopolysaccharide (LPS)-induced ALI.

METHODS

We used C57BL/6 mice (wild-type and PLD2 knockout (PLD2^-/-)) and human umbilical vein endothelial cell (HUVEC) models of sepsis-ALI. The pathological changes were evaluated by hematoxylin-eosin staining. Pulmonary vascular permeability was detected using wet-dry ratio, fluorescein isothiocyanate (FITC)-dextran, FITC-albumin, and immunoglobulin M concentration of bronchoalveolar lavage fluid. FITC-dextran and trans-endothelial electrical resistance assay were used to evaluate endothelial permeability on LPS-stimulated HUVECs. The mRNA expressions of TJ proteins were detected by real-time quantitative polymerase chain reaction. Then, protein levels were detected through Western blot analysis and immunofluorescence. The content of phosphatidic acid (PA), a downstream product of PLD2, was detected using an enzyme-linked immunosorbent assay kit.

RESULTS

PLD2 deficiency not only alleviated lung histopathological changes and improved pulmonary vascular permeability but also increased the survival rate of ALI mice. Knockout of PLD2 or treatment with the PLD2 inhibitor can reduce the damage of endothelial TJ proteins, namely, claudin5, occludin and zonula occludens protein-1, in sepsis-ALI mice and LPS-stimulated HUVECs. The level of the PLD2 catalytic product PA increased in LPS-stimulated HUVECs, and exogenous PA can reduce the TJ protein expression and increase signal transducer and activator of transcription 3 (STAT3) phosphorylation in vitro. Inhibition of STAT3 phosphorylation attenuated PA-induced degradation of endothelial TJs.

CONCLUSION

PLD2 knockout or inhibition may protect against LPS-induced lung injury by regulating the PA/STAT3 phosphorylation/endothelial TJ axis.

APELIN-13 AMELIORATES LPS-INDUCED ENDOTHELIAL-TO-MESENCHYMAL TRANSITION AND POST-ACUTE LUNG INJURY PULMONARY FIBROSIS BY SUPPRESSING TRANSFORMING GROWTH FACTOR-Β1 SIGNALING

ABSTRACT

The pathophysiology of acute respiratory distress syndrome (ARDS) involves cytokine storms, alveolar-capillary barrier destruction, and fibrotic progression. Pulmonary interstitial fibrosis is an important factor affecting the prognosis of ARDS patients. Endothelial-to-mesenchymal transition (EndMT) plays an important role in the development of fibrotic diseases, and the occurrence of EndMT has been observed in experimental models of LPS-induced acute lung injury (ALI). Apelin is an endogenous active polypeptide that plays an important role in maintaining endothelial cell homeostasis and inhibiting fibrotic progression in various diseases. However, whether apelin attenuates EndMT in ALI and post-ALI pulmonary fibrosis remains unclear. We analyzed the serum levels of apelin-13 in patients with sepsis-associated ARDS to examine its possible clinical value. A murine model of LPS-induced pulmonary fibrosis and an LPS-challenged endothelial cell injury model were used to analyze the protective effect and underlying mechanism of apelin-13. Mice were treated with apelin-13 by i.p. injection, and human pulmonary microvascular endothelial cells were incubated with apelin-13 in vitro . We found that the circulating apelin-13 levels were significantly elevated in sepsis-associated ARDS patients compared with healthy controls. Our study also confirmed that LPS induced EndMT progression and pulmonary fibrosis, which were characterized by decreased CD31 expression and increased α-smooth muscle actin expression and collagen deposition. LPS also stimulated the production of transforming growth factor β1 and activated the Smad signaling pathway. However, apelin-13 treatment significantly attenuated these changes. Our findings suggest that apelin-13 may be a novel biomarker in patients with sepsis-associated ARDS. These results demonstrate that apelin-13 ameliorates LPS-induced EndMT and post-ALI pulmonary fibrosis by suppressing transforming growth factor β1 signaling.

Neutrophil Extracellular Traps Induce Alveolar Macrophage Pyroptosis by Regulating NLRP3 Deubiquitination, Aggravating the Development of Septic Lung Injury

Background

Uncontrolled inflammation is a typical feature of sepsis-related lung injury. The key event in the progression of lung injury is Caspase-1-dependent alveolar macrophage (AM) pyroptosis. Similarly, neutrophils are stimulated to release neutrophil extracellular traps (NETs) to participate in the innate immune response. This study aims to illustrate the specific mechanisms by which NETs activate AM at the post-translational level and maintain lung inflammation.

Methods

We established a septic lung injury model by caecal ligation and puncture. We found elevated NETs and interleukin-1b (IL-1β) levels in the lung tissues of septic mice. Western blot and immunofluorescence analyses was utilized to determine whether NETs promote AM pyroptosis and whether degrading NETs or targeting the NLRP3 inflammasome had protective effects on AM pyroptosis and lung injury. Flow cytometric and co-immunoprecipitation analyses verified intracellular reactive oxygen species (ROS) levels and the binding of NLRP3 and ubiquitin (UB) molecules, respectively.

Results

Increased NETs production and IL-1β release in septic mice were correlated with the degree of lung injury. NETs upregulated the level of NLRP3, followed by NLRP3 inflammasome assembly and caspase-1 activation, leading to AM pyroptosis executed by the activated fragment of full-length gasdermin D (FH-GSDMD). However, the opposite effect was observed in the context of NETs degradation. Furthermore, NETs markedly elicited an increase in ROS, which facilitated the activation of NLRP3 deubiquitination and the subsequent pyroptosis pathway in AM. Removal of ROS could promote the binding of NLRP3 and ubiquitin, inhibit NLRP3 binding to apoptosis-associated spotted proteins (ASC) and further alleviate the inflammatory changes in the lungs.

Conclusion

In summary, these findings indicate that NETs prime ROS generation, which promotes NLRP3 inflammasome activation at the post-translational level to mediate AM pyroptosis and sustain lung injury in septic mice.

Using machine learning for the early prediction of sepsis-associated ARDS in the ICU and identification of clinical phenotypes with differential responses to treatment

Background: An early diagnosis model with clinical phenotype classification is key for the early identification and precise treatment of sepsis-associated acute respiratory distress syndrome (ARDS). This study aimed to: 1) build a machine learning diagnostic model for patients with sepsis-associated ARDS using easily accessible early clinical indicators, 2) conduct rapid classification of clinical phenotypes in this population, and 3) explore the differences in clinical characteristics, outcomes, and treatment responses of different phenotypes. Methods: This study is based on data from the Telehealth Intensive Care Unit (eICU) and Medical Information Mart for Intensive Care IV (MIMIC-IV). We trained and tested the early diagnostic model of sepsis-associated ARDS patients in the eICU. We used key predictive indicators to cluster sepsis-associated ARDS patients and determine the characteristics and clinical outcomes of different phenotypes, as well to explore the differences of in-hospital mortality among different the positive end-expiratory pressure (PEEP) levels in different phenotypes. These results are verified in MIMIC-IV to evaluate whether they are repeatable. Results: Among the diagnostic models constructed in 19,249 sepsis patients and 5,947 sepsis-associated ARDS patients, the AdaBoost (Decision Tree) model achieved the best performance with an area under the receiver operating characteristic curve (AUC) of 0.895, which is higher than that of the traditional Logistic Regression model (Z = -2.40,p = 0.013), and the accuracy of 70.06%, sensitivity of 78.11% and specificity of 78.74%. We simultaneously identified three sepsis-associated ARDS phenotypes. Cluster 0 (n = 3,669) had the lowest in-hospital mortality rate (6.51%) and fewer laboratory abnormalities (lower WBC (median:15.000 K/mcL), lower blood glucose (median:158.000 mg/dl), lower creatinine (median:1.200 mg/dl), lower lactic acid (median:3.000 mmol/L); p < 0.001). Cluster 1 (n = 1,554) had the highest in-hospital mortality rate (75.29%) and the most laboratory abnormalities (higher WBC (median:18.300 K/mcL), higher blood glucose (median:188.000 mg/dl), higher creatinine (median:2.300 mg/dl), higher lactic acid (median:3.900 mmol/L); p < 0.001). Cluster 2 (n = 724) had the most complex condition, with a moderate in-hospital mortality rate (29.7%) and the longest intensive care unit stay. In Clusters 0 and 1, patients with high PEEP had higher in-hospital mortality rate than those with low PEEP, but the opposite trend was seen in Cluster 2. These results were repeatable in 11,935 patients with sepsis and 2,699 patients with sepsis-associated ARDS patients in the MIMIC-IV cohort. Conclusion: A machine learning diagnostic model of sepsis-associated ARDS patients was established. Three phenotypes with different clinical features and outcomes were clustered, and these had different therapeutic responses. These findings are helpful for the early and rapid identification of sepsis-associated ARDS patients and their precise individualized treatment.

Prevention of mortality in acute lung injury induced by oleic acid: Application of polyherbal decoction (bronco T)

Acute lung injury (ALI) is a lethal respiratory disorder; directed uncontrolled inflammation, sloughing of the alveolar cells and their diffusion, and altered cardiorespiratory parameters with a global mortality rate of 40%. This study was designed to assess the preventive effect of a polyherbal decoction (Bronco T, 1.5 g/kg b. w.) on cardiorespiratory variables in oleic acid-induced ALI in rats. Oleic acid increases the level of neutrophil infiltration leading to pulmonary edema and alters the cardiorespiratory dynamics. The adult male rats were surgically cannulated and treated with intravenous oleic acid (0.38 ml/kg b. w.) to establish the ALI model. Bronco T was pre-administered orally 3 hours before oleic acid. The biophysical, histological, biochemical, and molecular effects were compared with dexamethasone (5 mg/kg b. w. i. p.). The animals were randomly divided into control, lethal, standard, and treatment groups. Respiratory frequency (RF), heart rate (HR), and mean arterial pressure (MAP) were recorded on a computerized chart recorder; arterial blood sample was collected to determine PaO₂/FiO₂, TNF-α, and MPO. Lipid peroxidation, superoxide dismutase, and catalase activity were evaluated to measure oxidative stress in bronchoalveolar lavage. Additionally, the pulmonary water content, COX-2 expression and histological examination were determined in the lung. A molecular docking study of the active phytoconstituent of BT obtained from HR-LCMS analysis against reported targets (IL-6, COX-2, TNFα, MPO and ENaC) of ALI was carried out. The B.T. pretreatment prevents mortality in comparison to the oleic acid group. It protects the lungs and heart from the detrimental effect of oleic acid, on par with dexamethasone. COX-2 mRNA expression was significantly down-regulated in the treatment group. The reduced level of TNF-α, MPO, SOD and catalase supported the protective effect of B.T. The in silico study revealed strong binding interaction between the phytoconstituent (Galangin 3- [galactosyl-(1–4)-rhamnoside and Beta solamarine] of BT and the reported target. The B.T. pre-administration attenuates the oleic acid-induced mortality and cardiorespiratory toxicity.

Precise Monitoring and Assessing Treatment Response of Sepsis-Induced Acute Lung Hypoxia with a Nitroreductase-Activated Golgi-Targetable Fluorescent Probe

Sepsis-induced acute lung injury (ALI) is mostly attributed to an outbreak of reactive oxygen species (ROS), which makes leukocytes infiltrate into the lung and results in lung hypoxia. Nitroreductase (NTR) is significantly upregulated under hypoxia, which is commonly regarded as a potential biomarker for assessing sepsis-induced acute lung hypoxia. Increasing evidence shows that NTR in the Golgi apparatus could be induced in sepsis-induced ALI. Meanwhile, the prolyl hydroxylase (PHD) inhibitor (dimethyloxalylglycine, DMOG) attenuated sepsis-induced ALI through further increasing the level of Golgi NTR by improving hypoxia inducible factor-1α (HIF-1α) activity, but as yet, no Golgi-targetable probe has been developed for monitoring and assessing treatment response of sepsis-induced ALI. Herein, we report a Golgi-targetable probe, Gol-NTR, for monitoring and assessing treatment response of sepsis-induced ALI through mapping the generation of NTR. The probe displayed high sensitivity with a low detection limit of 54.8 ng/mL and good selectivity to NTR. In addition, due to the excellent characteristics of Golgi-targetable, Gol-NTR was successfully applied in mapping the change of Golgi NTR in cells and zebrafish caused by various stimuli. Most importantly, the production of Golgi NTR in the sepsis-induced ALI and the PHD inhibitor (DMOG) against sepsis-induced ALI were visualized and precisely assessed for the first time with the assistance of Gol-NTR. The results demonstrated the practicability of Gol-NTR for the precise monitoring and assessing of the personalized treatment response of sepsis-induced ALI.

Sepsis-related cardiomyopathy: Not an easy task for ICU physicians

Sepsis-induced myocardial dysfunction is common. In addition to acute coronary syndrome, at least two types of left ventricular dysfunction can occur in septic patients: typical septic cardiomyopathy (SC) and sepsis-related takotsubo cardiomyopathy (ST). Although the definition of septic cardiomyopathy is based on left ventricular (LV) systolic dysfunction, both ventricles can be affected. In this context, it has been increasingly recognized that right ventricular (RV) systolic dysfunction is associated with long-term prognosis in septic patients. Unlike typical SC, ST patients usually displayed LV apical and circumferential mid-ventricular hypokinesia and basal hypercontractility. Timely and precise evaluation of heart dysfunction in sepsis patients is not easy but obviously mandatory. Further studies are still warranted regarding the mechanism, evaluation, and management of septic cardiomyopathy.

Mucin 1 Inhibits Ferroptosis and Sensitizes Vitamin E to Alleviate Sepsis-Induced Acute Lung Injury through GSK3β/Keap1-Nrf2-GPX4 Pathway

BACKGROUND

Ferroptosis is a nonapoptotic form of programmed cell death, which may be related to the occurrence and development of sepsis-induced acute respiratory distress syndrome (ARDS)/acute lung injury (ALI). Mucin 1 (MUC1) is a kind of macromolecule transmembrane glycoprotein. Previous studies have shown that MUC1 could relieve ALI in sepsis and predict whether sepsis patients would develop into ARDS. However, the role of MUC1 in the ferroptosis of sepsis-induced ALI/ARDS remains unclear.

MATERIALS AND METHODS

Sera samples from 50 patients with sepsis/septic shock were used to detect iron metabolism-related markers. Western blot and qRT-PCR were conducted to detect the expression levels of ferroptosis-related genes. Enzyme-linked immunosorbent assay (ELISA) was performed to evaluate inflammatory factors. Transmission electron microscopy (TEM) was used to assess morphological changes of cells.

RESULTS

The results showed that the iron metabolism-related indicators in sepsis-induced ARDS patients changed significantly, suggesting the iron metabolism disorder. The expression levels of ferroptosis-related genes in lung tissues of sepsis had marked changes, and the lipid peroxidation levels increased, while Ferrostatin-1 (Fer-1) could reverse the above results, which confirmed the occurrence of ferroptosis. In terms of mechanism studies, inhibition of MUC1 dimerization could increase the expression level of Keap1, reduce the phosphorylation level of GSK3β, inhibit the entry of Nrf2 into the nucleus, further inhibit the expression level of GPX4, enhance the lipid peroxidation level of lung tissues, trigger ferroptosis, and aggravate lung injury. Besides, inhibiting MUC1 reversed the alleviating effect of vitamin E on ALI caused by sepsis, increased the aggregation of inflammatory cells in lung tissues, and aggravated alveolar injury and edema.

CONCLUSIONS

Our study was the first to explore the changes of iron metabolism indicators in ALI/ARDS of sepsis, clarify the important role of ferroptosis in ALI/ARDS induced by sepsis, and reveal the effects and specific mechanisms of MUC1 in regulating ferroptosis, as well as the sensitization on vitamin E.