Liver-lung interactions in acute respiratory distress syndrome

Genome-wide assessment of shared genetic landscape of idiopathic pulmonary fibrosis and its comorbidities

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease accompanied by both local and systemic comorbidities. Genetic factors play a role in the development of IPF and certain associated comorbidities. Nevertheless, it is uncertain whether there are shared genetic factors underlying IPF and these comorbidities. To bridge this knowledge gap, we conducted a systematic investigation into the shared genetic architecture between IPF and ten prevalent heritable comorbidities (i.e., body mass index [BMI], coronary artery disease [CAD], chronic obstructive pulmonary disease [COPD], gastroesophageal reflux disease, lung cancer, major depressive disorder [MDD], obstructive sleep apnoea, pulmonary hypertension [PH], stroke, and type 2 diabetes), by utilizing large-scale summary data from their respective genome-wide association studies and multi-omics studies. We revealed significant (false discovery rate [FDR] < 0.05) and moderate genetic correlations between IPF and seven comorbidities, excluding lung cancer, MDD and PH. Evidence suggested a partially putative causal effect of IPF on CAD. Notably, we observed FDR-significant genetic enrichments in lung for the cross-trait between IPF and CAD and in liver for the cross-trait between IPF and COPD. Additionally, we identified 65 FDR-significant genes over-represented in 20 biological pathways related to the etiology of IPF, BMI, and COPD, including inflammation-related mucin gene clusters. Several of these genes were associated with clinically relevant drugs for the treatment of IPF, CAD, and/or COPD. Our results underscore the pervasive shared genetic basis between IPF and its common comorbidities and hold future implications for early diagnosis of IPF-related comorbidities, drug repurposing, and the development of novel therapies for IPF.

Extra-pulmonary control of respiratory defense

Pneumonia persists as a public health crisis, representing the leading cause of death due to infection. Whether respiratory tract infections progress to pneumonia and its sequelae such as acute respiratory distress syndrome and sepsis depends on numerous underlying conditions related to both the causative agent and host. Regarding the former, pneumonia burden remains staggeringly high, despite the effectiveness of pathogen-targeting strategies such as vaccines and antibiotics. This demands a greater understanding of host features that collaborate to promote immune resistance and tissue resilience in the infected lung. Such features inside the pulmonary compartment have drawn much attention, where major advances have been made related to resident and recruited immune activity. By comparison, extra-pulmonary processes guiding pneumonia susceptibility are relatively elusive, constituting the focus of this review. Here we will highlight examples of when, how, and why tissues outside of the lungs dispatch signals that modulate local immunity in the airspaces. Topics include the liver, gut, bone marrow, brain and more, all of which contribute in direct and indirect ways to pneumonia outcome. When tuned appropriately, it has become clear that these responses can serve protective roles, and this will be considered distinctly from what would otherwise be aberrant responses characteristic of pneumonia-induced organ injury and sepsis. Further advances in this area may reveal novel targetable areas for clinical intervention that are not confined to the intra-pulmonary space.

Hemodynamic effects of positive end-expiratory pressure

PURPOSE OF REVIEW

Positive end-expiratory pressure (PEEP) is required in the Berlin definition of acute respiratory distress syndrome and is a cornerstone of its treatment. Application of PEEP increases airway pressure and modifies pleural and transpulmonary pressures according to respiratory mechanics, resulting in blood volume alteration into the pulmonary circulation. This can in turn affect right ventricular preload, afterload and function. At the opposite, PEEP may improve left ventricular function, providing no deleterious effect occurs on the right ventricle.

RECENT FINDINGS

This review examines the impact of PEEP on cardiac function with regards to heart-lung interactions, and describes its consequences on organs perfusion and function, including the kidney, gut, liver and the brain. PEEP in itself is not beneficious nor detrimental on end-organ hemodynamics, but its hemodynamic effects vary according to both respiratory mechanics and association with other hemodynamic variables such as central venous or mean arterial pressure. There are parallels in the means of preventing deleterious impact of PEEP on the lungs, heart, kidney, liver and central nervous system.

SUMMARY

The quest for optimal PEEP settings has been a prominent goal in ARDS research for the last decades. Intensive care physician must maintain a high degree of vigilance towards hemodynamic effects of PEEP on cardiac function and end-organs circulation.

Peri-operative extracorporeal membrane oxygenation in adult and pediatric living donor liver transplantation: a single-center experience

Background

Extracorporeal membrane oxygenation (ECMO) is a potential rescue therapy for patients with acute cardiopulmonary dysfunction refractory to conventional treatment. In this study, we described the clinical profiles and outcomes of adult and pediatric living donor liver transplantation (LDLT) patients who received ECMO support during the peri-operative period.

Methods

From June 1994 to December 2020, eleven out of the 1,812 LDLTs performed at Kaohsiung Chang Gung Memorial Hospital required ECMO support: six for respiratory failure, three for cardiogenic shock, and two for refractory septic shock. Comparison between the survivor and non-survivor groups was made.

Results

The survival rate for liver transplantation (LT) patients on ECMO support is 36.4%-40% in adults and 33.3% in pediatrics, while the survival rate per indication is as follows: acute respiratory distress syndrome (ARDS) (50%), cardiogenic shock (33.3%), and sepsis (0%). Shorter durations of LT-to-ECMO and pre-ECMO mechanical ventilation were observed in the survivor group. On the other hand, we observed persistently elevated total bilirubin levels in non-survivors, while none of the survivors had aspartate aminotransferase (AST)/alanine aminotransferase (ALT) levels >1,000 U/L. A higher proportion of non-survivors were on concurrent continuous renal replacement therapy (CRRT).

Conclusions

Our experience has proven ECMO's utility during the peri-operative period for both adult and pediatric LDLT patients, more specifically for indications other than septic shock. Further studies are needed to better understand the factors leading to poor outcomes in order to identify patients who will more likely benefit from ECMO.

The pan-liver network theory: From traditional chinese medicine to western medicine

In traditional Chinese medicine (TCM), the liver is the "general organ" that is responsible for governing/maintaining the free flow of qi over the entire body and storing blood. According to the classic five elements theory, zang-xiang theory, yin-yang theory, meridians and collaterals theory, and the five-viscera correlation theory, the liver has essential relationships with many extrahepatic organs or tissues, such as the mother-child relationships between the liver and the heart, and the yin-yang and exterior-interior relationships between the liver and the gallbladder. The influences of the liver to the extrahepatic organs or tissues have been well-established when treating the extrahepatic diseases from the perspective of modulating the liver by using the ancient classic prescriptions of TCM and the acupuncture and moxibustion. In modern medicine, as the largest solid organ in the human body, the liver has the typical functions of filtration and storage of blood; metabolism of carbohydrates, fats, proteins, hormones, and foreign chemicals; formation of bile; storage of vitamins and iron; and formation of coagulation factors. The liver also has essential endocrine function, and acts as an immunological organ due to containing the resident immune cells. In the perspective of modern human anatomy, physiology, and pathophysiology, the liver has the organ interactions with the extrahepatic organs or tissues, for example, the gut, pancreas, adipose, skeletal muscle, heart, lung, kidney, brain, spleen, eyes, skin, bone, and sexual organs, through the circulation (including hemodynamics, redox signals, hepatokines, metabolites, and the translocation of microbiota or its products, such as endotoxins), the neural signals, or other forms of pathogenic factors, under normal or diseases status. The organ interactions centered on the liver not only influence the homeostasis of these indicated organs or tissues, but also contribute to the pathogenesis of cardiometabolic diseases (including obesity, type 2 diabetes mellitus, metabolic [dysfunction]-associated fatty liver diseases, and cardio-cerebrovascular diseases), pulmonary diseases, hyperuricemia and gout, chronic kidney disease, and male and female sexual dysfunction. Therefore, based on TCM and modern medicine, the liver has the bidirectional interaction with the extrahepatic organ or tissue, and this established bidirectional interaction system may further interact with another one or more extrahepatic organs/tissues, thus depicting a complex "pan-hepatic network" model. The pan-hepatic network acts as one of the essential mechanisms of homeostasis and the pathogenesis of diseases.

Hyperbilirubinemia as a Risk Factor for Mortality and Morbidity in Trauma Patients

Hyperbilirubinemia is frequently reported in trauma patients. However, few studies have investigated the effects of hyperbilirubinemia on patients' clinical trajectories. This study aimed to evaluate the relationship between hyperbilirubinemia and patient outcomes following trauma. Our study included 387 patients who were admitted to the trauma bay with severe trauma between January 2017 and December 2021. We categorized patients into two groups based on their peak bilirubin levels: the low-bilirubin (LB) group, with levels below 3 mg/dL, and the high-bilirubin (HB) group, with levels above 3 mg/dL. We then compared the rates of complications and mortality between these two groups. The incidence of pneumonia (10.8% vs. 32.3%, p < 0.001), acute kidney injury (AKI) (2.8% vs. 19.2%, p < 0.001), sepsis (2.8% vs. 10.1%, p = 0.003), and wound infections (8.3% vs. 30.3%, p < 0.001) was significantly higher in the HB group. Additionally, the mortality rate was significantly higher (4.2% vs. 10.1%, p = 0.028) in the HB group. Multivariate analysis revealed that the higher the bilirubin level, the greater the risk of complications (pneumonia: odds ratio [OR] = 3.238; 95% confidence interval [CI] = 1.68-6.22; p < 0.001, AKI: OR = 4.718; 95% CI = 1.65-13.44; p = 0.004, sepsis: OR = 3.087; 95% CI = 1.00-9.52; p = 0.04, wound infection: OR = 3.995; 95% CI = 2.073-7.700; p < 0.001). In conclusion, hyperbilirubinemia was associated with poorer outcomes in trauma patients.

Liver's influence on the brain through the action of bile acids

The liver partakes as a sensor and effector of peripheral metabolic changes and a regulator of systemic blood and nutrient circulation. As such, abnormalities arising from liver dysfunction can influence the brain in multiple ways, owing to direct and indirect bilateral communication between the liver and the brain. Interestingly, altered bile acid composition resulting from perturbed liver cholesterol metabolism influences systemic inflammatory responses, blood-brain barrier permeability, and neuron synaptic functions. Furthermore, bile acids produced by specific bacterial species may provide a causal link between dysregulated gut flora and neurodegenerative disease pathology through the gut-brain axis. This review will cover the role of bile acids-an often-overlooked category of active metabolites-in the development of neurological disorders associated with neurodegeneration. Further studies into bile acid signaling in the brain may provide insights into novel treatments against neurological disorders.

Alcohol use disorder in the intensive care unit a highly morbid condition, but chemical dependency discussion improves outcomes

BACKGROUND

Alcohol use disorders (AUD) are common in patients admitted to intensive care units (ICU) and increase the risk for worse outcomes. In this study, we describe factors associated with patient mortality after ICU admission and the effect of chemical dependency (CD) counseling on outcomes in the year following ICU admission.

METHODS

We retrospectively reviewed patient demographics, hospital data, and documentation of CD counseling by medical providers for all ICU patients with AUD admitted to our institution between January 2017 and March 2019. Primary outcomes were in-hospital and 1-year mortality.

RESULTS

Of the 527 patients with AUD requiring ICU care, median age was 56 years (range, 18-86). Both in-hospital (12%) and 1-year mortality rates (27%) were high. Rural patients, comorbidities, older age, need for mechanical ventilation, and complications were associated with increased risk of in-hospital and 1-year mortality. CD counseling was documented for 73% of patients, and 50% of these patients accepted alcohol treatment or resources prior to discharge. CD evaluation and acceptance was associated with a significantly decreased rate of readmission for liver or alcohol-related issues (36% vs. 58%; odds ratio [OR], 0.41; 95% confidence interval [CI], 0.27-0.61) and 1-year mortality (7% vs. 19.5%; OR, 0.32; 95% CI, 0.16-0.64). CD evaluation alone, regardless of patient acceptance, was associated with a significantly decreased 1-year post-discharge mortality rate (12% vs. 23%; OR, 0.44; 95% CI, 0.25-0.77).

CONCLUSIONS

ICU patients with AUD had high in-hospital and 1-year mortality. CD evaluation, regardless of patient acceptance, was associated with a significant decrease in 1-year mortality.

Interactions of Inhaled Liposome with Macrophages and Neutrophils Determine Particle Biofate and Anti-Inflammatory Effect in Acute Lung Inflammation

Since most current studies have focused on exploring how phagocyte internalization of drug-loaded nanovesicles by macrophages would affect the function and therapeutic effects of infiltrated neutrophils or monocytes, research has evaluated the specificity of the inhaled nanovesicles for targeting various phagocytes subpopulations. In this study, liposomes with various charges (including neutral (L1), anionic (L2), and cationic at inflammatory sites (L3)) were constructed to investigate how particle charge determined their interactions with key phagocytes (including macrophages and neutrophils) in acute lung injury (ALI) models and to establish correlations with their biofate and overall anti-inflammatory effect. Our results clearly indicated that neutrophils were capable of rapidly sequestering L3 with a 3.2-fold increase in the cellular liposome distribution, compared to that in AMs, while 70.5% of L2 were preferentially uptaken by alveolar macrophages (AMs). Furthermore, both AMs and the infiltrated neutrophils performed as the potential vesicles for the inhaled liposomes to prolong their lung retention in ALI models, whereas AMs function as sweepers to recognize and process liposomes in the healthy lung. Finally, inhaled roflumilast-loaded macrophage or neutrophil preferential liposomes (L2 or L3) exhibited optimal anti-inflammatory effect because of the decreased AMs phagocytic capacity or the prolonged circulation times of neutrophils. Such findings will be beneficial in exploiting a potential pathway to specifically manipulate lung phagocyte functions in lung inflammatory diseases where these cells play crucial roles.

The Impact of Nonalcoholic Fatty Liver Disease on Severe Community-Acquired Pneumonia Outcomes

Community-acquired pneumonia (CAP) is one of the leading causes of morbidity and mortality, while nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. NAFLD is associated with systemic changes in immune response, possibly linked to CAP severity. However, the impact of NAFLD on CAP outcomes has not been determined. The aim of this study was to evaluate clinical course, complications and outcomes of severe CAP requiring ICU treatment in patients with NAFLD in the pre-COVID-19 era. A retrospective cohort study included 138 consecutively hospitalized adult patients with severe CAP admitted to the ICU during a 4-year period: 80 patients with NAFLD and 58 controls. Patients with NAFLD more frequently presented with ARDS (68.7% vs. 43.1%), and required invasive mechanical ventilation (86.2% vs. 63.8%), respiratory ECMO (50% vs. 24.1%), and continuous renal replacement therapy (62.5% vs. 29.3%). Mortality was significantly higher in the NAFLD group (50% vs. 20.7%), and the time from hospital admission to death was significantly shorter. In survival analysis, NAFLD (HR 2.21, 95%CI 1.03-5.06) was associated with mortality independently of other components of metabolic syndrome. In conclusion, our study identified NAFLD as an independent predictor of mortality in patients with severe CAP.

Total bilirubin is associated with all-cause mortality in patients with acute respiratory distress syndrome: a retrospective study

Background

Acute respiratory distress syndrome (ARDS) is a life-threatening disease for which biomarkers to predict mortality are needed. Total bilirubin (TBIL), an end-product of hemoglobin catabolism in mammals reflecting liver dysfunction, has been demonstrated as an independent risk indicator for critically ill patients. This study aimed to examine whether TBIL on intensive care unit (ICU) admission is associated with ARDS mortality.

Methods

We analyzed the data of patients diagnosed with ARDS according to the Berlin definition from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. The primary endpoint was 30-day ICU mortality after admission to the ICU, and the second endpoint was in-hospital mortality. Multivariable logistic analysis adjusted for potential confounders was used to determine the association between TBIL and short-term mortality.

Results

Of 1,539 ARDS patients enrolled, 261 patients died within 30 days of admission to the ICU. In the multivariable logistic analysis, each 1 g/dL increase in TBIL levels led to a 4% increase in the odds of 30-day ICU mortality [adjusted odds ratio (OR) =0.04; 95% confidence interval (CI): 0.01 to 0.08] and a 4% increase in the odds of in-hospital mortality (adjusted OR =0.04; 95% CI: 0.01 to 0.07). Furthermore, TBIL levels ≥2 mg/dL were significantly associated with 30-day ICU mortality (adjusted OR =1.51, 95% CI: 1.02 to 1.07) and in-hospital mortality (OR =1.41; 95% CI: 1.01 to 1.87). Similarly, associations between serum TBIL levels and 30-day ICU mortality were found in all subgroups stratified by comorbidities, the severity of ARDS, and other variables.

Conclusions

A higher serum TBIL on ICU admission was independently associated with mortality in ARDS patients. Intensive care and observation should be provided to ARDS patients with increased TBIL.

Paediatric dengue shock syndrome and acute respiratory failure: a single-centre retrospective study

OBJECTIVE

Dengue shock syndrome (DSS) is a serious health condition leading to paediatric intensive care unit (PICU) admissions and deaths in tropical countries. Acute respiratory failure (ARF) is associated with DSS and is a major cause of dengue deaths. We aimed to identify risk factors associated with ARF in children with DSS.

METHODS

We retrospectively reviewed children with DSS admitted to a PICU from 2010 to 2020 at a tertiary level hospital in Bangkok, Thailand. Patient characteristics, clinical parameters and laboratory data were collected. Multivariable logistic regression analysis was used to identify factors associated with ARF.

RESULTS

Twenty-six (43.3%) of 60 children with DSS developed ARF and 6 did not survive to day 28. The median (IQR) age was 8.1 years (IQR 4.0-11.0). Fluid accumulation during the first 72 hours of PICU admission was greater in the ARF group compared with the non-ARF group (12.2% (IQR 7.6-21.7) vs 8.3% (IQR 4.4-13.3), p=0.009). In a multivariate analysis at 72 hours post PICU admission, the presence of ˃15% fluid accumulation was independently associated with ARF (adjusted OR 5.67, 95% CI 1.24 to 25.89, p=0.025).

CONCLUSION

ARF is an important complication in children with DSS. A close assessment of patient fluid status is essential to identify patients at risk of ARF. Once the patient is haemodynamically stable and leakage slows, judicious fluid management is required to prevent ARF.

Oral Supplementation with the Polyamine Spermidine Affects Hepatic but Not Pulmonary Lipid Metabolism in Lean but Not Obese Mice

The polyamine spermidine is discussed as a caloric restriction mimetic and therapeutic option for obesity and related comorbidities. This study tested oral spermidine supplementation with regard to the systemic, hepatic and pulmonary lipid metabolism under different diet conditions. Male C57BL/6 mice were fed a purified control (CD), high sucrose (HSD) or high fat (HFD) diet with (-S) or without spermidine for 30 weeks. In CD-fed mice, spermidine decreased body and adipose tissue weights and reduced hepatic lipid content. The HSD induced hepatic lipid synthesis and accumulation and hypercholesterolemia. This was not affected by spermidine supplementation, but body weight and blood glucose were lower in HSD-S compared to HSD. HFD-fed mice showed higher body and fat depot weights, prediabetes, hypercholesterolemia and severe liver steatosis, which were not altered by spermidine. Within the liver, spermidine diminished hepatic expression of lipogenic transcription factors SREBF1 and 2 under HSD and HFD and affected the expression of other lipid-related enzymes. In contrast, diet and spermidine exerted only minor effects on pulmonary parameters. Thus, oral spermidine supplementation affects lipid metabolism in a diet-dependent manner, with significant reductions in body fat and weight under physiological nutrition and positive effects on weight and blood glucose under high sucrose intake, but no impact on dietary fat-related parameters.

Are Cirrhotic Patients Receiving Invasive Mechanical Ventilation at Risk of Abundant Microaspiration

Previous studies have identified cirrhosis as a risk factor for ventilator-associated pneumonia (VAP). The aim of our study was to determine the relationship between cirrhosis and abundant gastric-content microaspiration in intubated critically ill patients. We performed a matched cohort study using data from three randomized controlled trials on abundant microaspiration in patients under mechanical ventilation. Each cirrhotic patient was matched with three to four controls for gender, age ± 5 years and simplified acute physiology score II (SAPS II) ± 5 points. Abundant microaspiration was defined by significant levels of pepsin and alpha-amylase in >30% of tracheal aspirates. All tracheal aspirates were collected for the first 48 h of the study period. The percentage of patients with abundant gastric-content microaspiration was the primary outcome. The abundant microaspiration of oropharyngeal secretions, VAP incidence, the duration of mechanical ventilation, length of intensive care unit (ICU) stay and mortality were the secondary outcomes. A. total of 39 cirrhotic patients were matched to 138 controls. The percentage of patients with abundant gastric-content microaspiration did not differ between the two groups (relative risk: 0.91 (95% CI: 0.75 to 1.10)). There was no significant difference between the two groups in terms of the abundant microaspiration of oropharyngeal secretions, VAP, the duration of mechanical ventilation, the length of ICU stay and mortality. Our results suggest that cirrhosis is not associated with abundant gastric-content microaspiration.

The liver in sepsis: molecular mechanism of liver failure and their potential for clinical translation

Liver failure is a life-threatening complication of infections restricting the host's response to infection. The pivotal role of the liver in metabolic, synthetic, and immunological pathways enforces limits the host's ability to control the immune response appropriately, making it vulnerable to ineffective pathogen resistance and tissue damage. Deregulated networks of liver diseases are gradually uncovered by high-throughput, single-cell resolved OMICS technologies visualizing an astonishing diversity of cell types and regulatory interaction driving tolerogenic signaling in health and inflammation in disease. Therefore, this review elucidates the effects of the dysregulated host response on the liver, consequences for the immune response, and possible avenues for personalized therapeutics.

Alcoholic liver disease: a new insight into the pathogenesis of liver disease

Excessive alcohol consumption contributes to a broad clinical spectrum of liver diseases, from simple steatosis to end-stage hepatocellular carcinoma. The liver is the primary organ that metabolizes ingested alcohol and is exquisitely sensitive to alcohol intake. Alcohol metabolism is classified into two pathways: oxidative and non-oxidative alcohol metabolism. Both oxidative and non-oxidative alcohol metabolisms and their metabolites have toxic consequences for multiple organs, including the liver, adipose tissue, intestine, and pancreas. Although many studies have focused on the effects of oxidative alcohol metabolites on liver damage, the importance of non-oxidative alcohol metabolites in cellular damage has also been discovered. Furthermore, extrahepatic alcohol effects are crucial for providing additional information necessary for the progression of alcoholic liver disease. Therefore, studying the effects of alcohol-producing metabolites and interorgan crosstalk between the liver and peripheral organs that express ethanol-metabolizing enzymes will facilitate a comprehensive understanding of the pathogenesis of alcoholic liver disease. This review focuses on alcohol-metabolite-associated hepatotoxicity due to oxidative and non-oxidative alcohol metabolites and the role of interorgan crosstalk in alcoholic liver disease pathogenesis.

Obesity Reshapes the Microbial Population Structure along the Gut-Liver-Lung Axis in Mice

The microbiome is emerging as a major player in tissue homeostasis in health and disease. Gut microbiome dysbiosis correlates with several autoimmune and metabolic diseases, while high-fat diets and ensuing obesity are known to affect the complexity and diversity of the microbiome, thus modulating pathophysiology. Moreover, the existence of a gut-liver microbial axis has been proposed, which may extend to the lung. In this context, we systematically compared the microbiomes of the gut, liver, and lung of mice fed a high-fat diet to those of littermates fed a matched control diet. We carried out deep sequencing of seven hypervariable regions of the 16S rRNA microbial gene to examine microbial diversity in the tissues of interest. Comparison of the local microbiomes indicated that lung tissue has the least diverse microbiome under healthy conditions, while microbial diversity in the healthy liver clustered closer to the gut. Obesity increased microbial complexity in all three tissues, with lung microbial diversity being the most modified. Obesity promoted the expansion of Firmicutes along the gut-liver-lung axis, highlighting staphylococcus as a possible pathologic link between obesity and systemic pathophysiology, especially in the lungs.

High levels of eicosanoids and docosanoids in the lungs of intubated COVID-19 patients

Severe acute respiratory syndrome coronavirus 2 is responsible for coronavirus disease 2019 (COVID-19). While COVID-19 is often benign, a subset of patients develops severe multilobar pneumonia that can progress to an acute respiratory distress syndrome. There is no cure for severe COVID-19 and few treatments significantly improved clinical outcome. Dexamethasone and possibly aspirin, which directly/indirectly target the biosynthesis/effects of numerous lipid mediators are among those options. Our objective was to define if severe COVID-19 patients were characterized by increased bioactive lipids modulating lung inflammation. A targeted lipidomic analysis of bronchoalveolar lavages (BALs) by tandem mass spectrometry was done on 25 healthy controls and 33 COVID-19 patients requiring mechanical ventilation. BALs from severe COVID-19 patients were characterized by increased fatty acids and inflammatory lipid mediators. There was a predominance of thromboxane and prostaglandins. Leukotrienes were also increased, notably LTB₄ , LTE₄ , and eoxin E₄ . Monohydroxylated 15-lipoxygenase metabolites derived from linoleate, arachidonate, eicosapentaenoate, and docosahexaenoate were also increased. Finally yet importantly, specialized pro-resolving mediators, notably lipoxin A₄ and the D-series resolvins, were also increased, underscoring that the lipid mediator storm occurring in severe COVID-19 involves pro- and anti-inflammatory lipids. Our data unmask the lipid mediator storm occurring in the lungs of patients afflicted with severe COVID-19. We discuss which clinically available drugs could be helpful at modulating the lipidome we observed in the hope of minimizing the deleterious effects of pro-inflammatory lipids and enhancing the effects of anti-inflammatory and/or pro-resolving lipid mediators.

Microarray and Bioinformatics Analysis of Circular RNA Differential Expression in Newborns With Acute Respiratory Distress Syndrome

Previous studies pointed out that a variety of microRNAs (miRNAs) are involved in the pathogenesis of neonatal acute respiratory distress syndrome (NARDS) and play different roles in the pathological process. However, there have been few studies reporting the connection between circular RNA (circRNA) and NARDS, so the expression profile of circRNAs in newborns with acute respiratory distress syndrome remains largely unknown. In the present study, 10 samples obtained from remaining clinical blood samples of newborns hospitalized in a neonatal ward of the First Affiliated Hospital of Nanjing Medical University from January 2020 to October 2020 were divided into the "NARDS" group and "non-NARDS" group according to the Montelux standard and then were analyzed in microarray, and 10 other samples collected from the same place and from January 1, 2021 to August 31, 2021, were used to do RT-qPCR experiment. circRNA expression profiles, in which 741 circRNAs were downregulated and 588 were upregulated, were screened with circRNA high-throughput sequencing. Subsequently, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of parent genes of the differentially expressed circRNAs revealed that these circRNAs may be related to the process of protein synthesis and metabolism in NARDS. Moreover, five circRNAs-hsa_circ_0058495, hsa_circ_0000367, hsa_circ_0005389, hsa_circ_0059571, and hsa_circ_0006608-were selected randomly among the top 10 circRNAs of the downregulated or upregulated expression profiles. Then, bioinformatics tools were used to predict correlative miRNA and its target genes, which were also subjected to the same bioinformatics analysis for further study. The top 30 enriched KEGG pathway analyses of the 125 target genes suggested that these target genes are widely involved in the synthesis and secretion of endocrine hormones, and the top 30 enriched GO terms based on the 125 target genes are also focused on the protein and DNA processing. Thus, the present results show that circRNAs could promote the inflammation of NARDS which may provide a new therapeutic direction and it can be used as molecular markers for early diagnosis of NARDS, but further molecular biology verification is needed to define the specific role of differentially expressed circRNAs in NARDS.