Deep phenotyping of the lipidomic response in COVID-19 and non-COVID-19 sepsis

Mast cell activation signature as a potential biomarker in COVID-19

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, represented a public health challenge due to the absence of effective treatments to combat the disease. Lethality associated with SARS-CoV-2 infection results from an exacerbated immune response that mediates clinical disease progression and compromises respiratory capacity and organ function. In the lungs, one of the cell lineages increased during COVID-19 are mast cells (MC), cells of innate immune response known for their ability to promote inflammation through the release of their pre-formed mediators or de novo synthesis. The role of MC-derived mediators during SARS-CoV-2 infection and their association with the development of severe COVID-19 have been poorly described. In a previous report, we demonstrated the predictive ability of carboxypeptidase A3 (CPA3) to determine COVID-19 severity. However, it is currently unclear whether the use of other mast cell-derived mediators could improve this predictive ability. To address this gap, we evaluated levels of total tryptase, CPA3, chymase, and prostaglandin D2 (PGD2) in serum from patients with non-severe and severe COVID-19 to develop a predictive model of severe COVID-19 outcomes. We demonstrate that the combined use of these mediators enhances their predictive ability for MC activation during SARS-CoV-2 infection and their involvement in severe forms of COVID-19. Based on these findings, a serum MC activation profile can be proposed as a promising biomarker for SARS-CoV-2 infection and may contribute to the development of targeted therapeutic strategies to improve patient outcomes.

Lipidomics reveals effect of EHHADH in lung squamous cell

Lung squamous cell carcinoma (LUSC) and lung adenocarcinoma (LUAD) are two major pathological types of non-small cell lung cancer (NSCLC), characterized by distinct patterns of lipid metabolism. However, the molecular mechanisms underlying lipid metabolism reprogramming specific to LUSC remain poorly understood. This study aims to fill this gap by identifying and characterizing EHHADH (enoyl-CoA, hydratase/3-hydroxyacyl CoA dehydrogenase) as a key regulator of medium-chain fatty acid metabolism in LUSC. The peroxisomal L-bifunctional enzyme is one of the important elements to control the peroxisomal fatty acid beta-oxidation pathway. Through high-expression genes related to lipid metabolism were identified by data mining, the expression and regulatory effects of EHHADH in different cell lines were investigated. EHHADH was highly expressed in LUSC cells and exhibited different expression patterns from those in LUAD cells. Knockdown of EHHADH in LUSC cell lines led to a marked reduction in cell proliferation. RNA sequencing following EHHADH silencing demonstrated significant changes in the expression of lipid metabolism-related genes in different cell lines, such as AZGP1, CAV1, CYP3A4, NR2F2, NR3C2, and RARG. Lipidomics analysis further demonstrated that EHHADH plays a crucial role in regulating intracellular and extracellular lipid profiles. EHHADH knockdown resulted in increased levels of long-chain fatty acids and storage lipids, while decreased levels of medium-chain fatty acids. Conversely, overexpression of EHHADH reduced long-chain fatty acids and storage lipids, while increasing specific medium-chain fatty acids. These metabolic alterations were consistent with changes in lipid metabolism-related protein expression, supporting the molecular mechanistic role of EHHADH in lipid regulation. In conclusion, EHHADH functions as an important regulator of lipid metabolism in LUSC and plays a key role in the occurrence, progression, and treatment of lung cancer. The important impact of EHHADH in lipid metabolism disorders suggests potential utility as a biomarker for diagnosis and a target for personalized treatment strategies in lung cancer.

Enhanced Production of Lipid Mediators in Plasma and Activation of DNA Damage Pathways in PBMCs Are Correlated With the Severity of Ancestral SARS-CoV-2 Infection

Many questions remain unanswered regarding the implication of genetics and lipid metabolites with severe SARS-CoV-2 infections. We performed bulk RNA-seq and a total fatty acid panel analysis on PBMCs and plasma collected from 10 infected and 10 uninfected patients. Univariate comparison of lipid metabolites using the Mann-Whitney U-test revealed that six lipid metabolites were significantly increased in COVID-19 patients, including the lipid mediators arachidonic acid (AA) and eicosapentaenoic acid (EPA), which both give rise to eicosanoids. Key lipids implicated in inflammation, including AA and EPA, along with the fatty acids DHA and DPA, were significantly and positively correlated to the WHO disease severity score. Analysis of our bulk RNA-seq dataset demonstrated distinct transcriptional profiles leading to a segregation of COVID-19 patients based on the WHO score. Ontology, KEGG, and Reactome analysis identified several key pathways and nodes that were enriched for genes related to innate immunity, interactions between lymphoid and nonlymphoid cells, interleukin signaling, and subsequent DNA damage pathways. EPA levels correlated with heightened cell cycling and DNA damage pathways observed in patients with a high WHO score. We studied gene expression in nasopharyngeal swabs from 58 healthy and COVID-19 participants and identified that genes implicated in eicosanoid synthesis, such as alox5, alox12, and alox15B, were specifically up-regulated in high WHO score patients in several cell types of the nasopharynx, especially goblet cells across different viral variants (Deta and Omicron). Using published nasal scRNA-seq datasets from COVID-19 patients, we evaluated the expression of genes implicated in eicosanoid synthesis, such as ALOX5, ALOX15, and ALOX15B, across nasal cell types and COVID-19 severity groups. Altogether, our study highlights the fact that the increase in specific lipids implicated in inflammation and the genes required for their synthesis correlated with the severity of the SARS-CoV-2 infection.

Deficiency in platelet 12-lipoxygenase exacerbates inflammation and disease severity during SARS-CoV-2 infection

Platelets, known for maintaining blood balance, also participate in antimicrobial defense. Upon severeacute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, platelets become hyperactivated, releasing molecules such as cytokines, granule contents, and bioactive lipids. The key effector biolipids produced by platelets include 12-hydroxyeicosatetraenoic acid (12-HETE) and 12-hydroxyeicosatrienoic acid (12-HETrE), produced by 12-lipoxygenase (12-LOX), and prostaglandins and thromboxane, produced by cyclooxygenase-1. While prostaglandin E2 and thromboxane B2 were previously associated with lung inflammation in severe COVID-19, the role of platelet 12-LOX in SARS-CoV-2 infection remains unclear. Using mice deficient for platelets' 12-LOX, we report that SARS-CoV-2 infection resulted in higher lung inflammation characterized by histopathological tissue analysis, increased leukocyte infiltrates, and cytokine production relative to wild-type mice. In addition, distinct platelet and lung transcriptomic changes, including alterations in NOD-like receptor (NLR) family pyrin domain-containing 1 (NLRP1) inflammasome-related gene expression, were observed. Mass spectrometry lipidomic analysis in 12-LOX-deficient-infected mice revealed significant changes in bioactive lipid content, including reduced levels of 12-HETrE that inversely correlated with disease severity. Finally, platelet 12-LOX deficiency was associated with increased morbidity and lower survival rates relative to wild type (WT) mice. Overall, this study highlights the complex interplay between 12-LOX-related lipid metabolism and inflammatory responses during SARS-CoV-2 infection. The findings provide valuable insights into potential therapeutic targets aimed at mitigating severe outcomes, emphasizing the pivotal role of platelet enzymes in the host response to viral infections.

Delayed viral clearance and altered inflammatory responses affect severity of SARS-CoV-2 infection in aged mice

Epidemiological investigations consistently demonstrate an overrepresentation of the elderly in COVID-19 hospitalizations and fatalities, making the advanced age as a major predictor of disease severity. Despite this, a comprehensive understanding of the cellular and molecular mechanisms explaining how old age represents a major risk factor remain elusive. To investigate this, we compared SARS-CoV-2 infection outcomes in young adults (2 months) and geriatric (15-22 months) mice. Both groups of K18-ACE2 mice were intranasally infected with 500 TCID50 of SARS-CoV-2 Delta variant with analyses performed on days 3, 5, and 7 post-infection (DPI). Analyses included pulmonary cytokines, lung RNA-seq, viral loads, lipidomic profiles, and histological assessments, with a concurrent evaluation of the percentage of mice reaching humane endpoints. The findings unveiled notable differences, with aged mice exhibiting impaired viral clearance, reduced survival, and failure to recover weight loss due to infection. RNA-seq data suggested greater lung damage and reduced respiratory function in infected aged mice. Additionally, elderly-infected mice exhibited a deficient antiviral response characterized by reduced Th1-associated mediators (IFNγ, CCL2, CCL3, CXCL9) and diminished number of macrophages, NK cells, and T cells. Furthermore, mass-spectrometry analysis of the lung lipidome indicated altered expression of several lipids with immunomodulatory and pro-resolution effects in aged mice such as Resolvin, HOTrEs, and NeuroP, but also DiHOMEs-related ARDS. These findings indicate that aging affects antiviral immunity, leading to prolonged infection, greater lung damage, and poorer clinical outcomes. This underscores the potential efficacy of immunomodulatory treatments for elderly subjects experiencing symptoms of severe COVID-19.

Metabolomics- and proteomics-based multi-omics integration reveals early metabolite alterations in sepsis-associated acute kidney injury

BACKGROUND

Sepsis-associated acute kidney injury (SA-AKI) is a frequent complication in patients with sepsis and is associated with high mortality. Therefore, early recognition of SA-AKI is essential for administering supportive treatment and preventing further damage. This study aimed to identify and validate metabolite biomarkers of SA-AKI to assist in early clinical diagnosis.

METHODS

Untargeted renal proteomic and metabolomic analyses were performed on the renal tissues of LPS-induced SA-AKI and sepsis mice. Glomerular filtration rate (GFR) monitoring technology was used to evaluate real-time renal function in mice. To elucidate the distinctive characteristics of SA-AKI, a multi-omics Spearman correlation network was constructed integrating core metabolites, proteins, and renal function. Subsequently, metabolomics analysis was used to explore the dynamic changes of core metabolites in the serum of SA-AKI mice at 0, 8, and 24 h. Finally, a clinical cohort (28 patients with SA-AKI vs. 28 patients with sepsis) serum quantitative metabolomic analysis was carried out to build a diagnostic model for SA-AKI via logistic regression (LR).

RESULTS

Thirteen differential renal metabolites and 112 differential renal proteins were identified through a multi-omics study of SA-AKI mice. Subsequently, a multi-omics correlation network was constructed to highlight five core metabolites, i.e., 3-hydroxybutyric acid, 3-hydroxymethylglutaric acid, creatine, myristic acid, and inosine, the early changes of which were then observed via serum time series experiments of SA-AKI mice. The levels of 3-hydroxybutyric acid, 3-hydroxymethylglutaric acid, and creatine increased significantly at 24 h, myristic acid increased at 8 h, while inosine decreased at 8 h. Ultimately, based on the identified core metabolites, we recruited 56 patients and constructed a diagnostic model named IC3, using inosine, creatine, and 3-hydroxybutyric acid, to early identify SA-AKI (AUC = 0.90).

CONCLUSIONS

We proposed a blood metabolite model consisting of inosine, creatine, and 3-hydroxybutyric acid for the early screening of SA-AKI. Future studies will observe the performance of these metabolites in other clinical populations to evaluate their diagnostic role.

Human genetics identify convergent signals in mitochondrial LACTB-mediated lipid metabolism in cardiovascular-kidney-metabolic syndrome

The understanding of cardiovascular-kidney-metabolic syndrome remains difficult despite recently performed large scale genome-wide association studies. Here, we identified beta-lactamase (LACTB), a novel gene whose expression is targeted by genetic variations causing kidney dysfunction and hyperlipidemia. Mice with LACTB deletion developed impaired glucose tolerance, elevated lipid levels, and increased sensitivity to kidney disease, while mice with tubule-specific overexpression of LACTB were protected from kidney injury. We show that LACTB is a novel mitochondrial protease cleaving and activating phospholipase A2 group VI (PLA2G6), a kidney-metabolic risk gene itself. Genetic deletion of PLA2G6 in tubule-specific LACTB-overexpressing mice abolished the protective function of LACTB. Via mouse and human lipidomic studies, we show that LACTB and downstream PLA2G6 convert oxidized phosphatidylethanolamine to lyso-phosphatidylethanolamine and thereby regulate mitochondrial function and ferroptosis. In summary, we identify a novel gene and a core targetable pathway for kidney-metabolic disorders.

Causal relationship between lipidome and acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS), with high morbidity and mortality, is a common clinical syndrome of acute respiratory failure caused by diffuse lung inflammation and edema. ARDS can precipitate in various ways. The complex pathophysiology of ARDS involves the activation and dysregulation of multiple metabolisms and immune responses. Using summary-level data from a genome-wide association study (GWAS), a two-sample Mendelian randomization (MR) analysis of 179 genetically predicted lipid species and ARDS (375 cases, 406,518 controls) was performed and validated in plasma and pulmonary edema fluid from 24 patients. Furthermore, we used a two-step MR to quantify the effect of immune cell-mediated lipids on ARDS. We identified 8 lipids (Cholesterol, Phosphatidylcholine (14:0_16:0), Phosphatidylcholine (16:0_20:5), Phosphatidylcholine (18:0_18:2), Phosphatidylethanolamine (18:1_18:1), Triacylglycerol (51:2), Triacylglycerol (52:4), and Triacylglycerol (54:3) ) associated with ARDS. The proportions of genetically-predicted lipids mediated by the four types of immune cells were determined. Sensitivity analysis did not reveal any obvious pleiotropy or heterogeneity. Our study demonstrates the power of multivariate genetic analysis in correlated lipidomic data and reveals genetic links between ARDS and lipid species beyond standard lipids.

Unraveling SARS-CoV-2 Host-Response Heterogeneity through Longitudinal Molecular Subtyping

Hospitalized COVID-19 patients exhibit diverse immune responses during acute infection, which are associated with a wide range of clinical outcomes. However, understanding these immune heterogeneities and their links to various clinical complications, especially long COVID, remains a challenge. In this study, we performed unsupervised subtyping of longitudinal multi-omics immunophenotyping in over 1,000 hospitalized patients, identifying two critical subtypes linked to mortality or mechanical ventilation with prolonged hospital stay and three severe subtypes associated with timely acute recovery. We confirmed that unresolved systemic inflammation and T-cell dysfunctions were hallmarks of increased severity and further distinguished patients with similar acute respiratory severity by their distinct immune profiles, which correlated with differences in demographic and clinical complications. Notably, one critical subtype (SubF) was uniquely characterized by early excessive inflammation, insufficient anticoagulation, and fatty acid dysregulation, alongside higher incidences of hematologic, cardiac, and renal complications, and an elevated risk of long COVID. Among the severe subtypes, significant differences in viral clearance and early antiviral responses were observed, with one subtype (SubC) showing strong early T-cell cytotoxicity but a poor humoral response, slower viral clearance, and greater risks of chronic organ dysfunction and long COVID. These findings provide crucial insights into the complex and context-dependent nature of COVID-19 immune responses, highlighting the importance of personalized therapeutic strategies to improve both acute and long-term outcomes.

Identification of CRTH2 as a New PPARγ-Target Gene in T Cells Suggested CRTH2 Dependent Conversion of Th2 Cells as Therapeutic Concept in COVID-19 Infection

Background

COVID-19 is a serious viral infection, which is often associated with a lethal outcome. Therefore, understanding mechanisms, which affect the immune response during SARS-CoV2 infection, are important.

Methods

To address this, we determined the number of T cells in peripheral blood derived from intensive care COVID-19 patients. Based on our previous studies, evaluating PPARγ-dependent T cell apoptosis in sepsis patients, we monitored PPARγ expression. We performed a next generation sequencing approach to identify putative PPARγ-target genes in Jurkat T cells and used a PPARγ transactivation assay in HEK293T cells. Finally, we translated these data to primary T cells derived from healthy donors.

Results

A significantly reduced count of total CD3+ T lymphocytes and the CD4+ and CD8+ subpopulations was observed. Also, the numbers of anti-inflammatory, resolutive Th2 cells and FoxP3-positive regulatory T cells (Treg) were decreased. We observed an augmented PPARγ expression in CD4+ T cells of intensive care COVID-19 patients. Adapted from a next generation sequencing approach in Jurkat T cells, we found the chemoattractant receptor-homologous molecule expressed on T helper type 2 cells (CRTH2) as one gene regulated by PPARγ in T cells. This Th2 marker is a receptor for prostaglandin D and its metabolic degradation product 15-deoxy-∆12,14-prostaglandin J2 (15d-PGJ2), an established endogenous PPARγ agonist. In line, we observed an increased PPARγ transactivation in response to 15d-PGJ2 treatment in HEK293T cells overexpressing CRTH2. Translating these data to primary T cells, we found that Th2 differentiation was associated with an increased expression of CRTH2. Interestingly, these CRTH2+ T cells were prone to apoptosis.

Conclusion

These mechanistic data suggest an involvement of PPARγ in Th2 differentiation and T cell depletion in COVID-19 patients.

SPMs exert anti-inflammatory and pro-resolving effects through positive allosteric modulation of the prostaglandin EP4 receptor

Inflammation is a protective response to pathogens and injury. To be effective it needs to be resolved by endogenous mechanisms in order to avoid prolonged and excessive inflammation, which can become chronic. Specialized pro-resolving mediators (SPMs) are a group of lipids derived from omega-3 fatty acids, which can induce the resolution of inflammation. How SPMs exert their anti-inflammatory and pro-resolving effects is, however, not clear. Here, we show that SPMs such as protectins, maresins, and D-series resolvins function as biased positive allosteric modulators (PAM) of the prostaglandin E2 (PGE2) receptor EP4 through an intracellular binding site. They increase PGE2-induced Gs-mediated formation of cAMP and thereby promote anti-inflammatory signaling of EP4. In addition, SPMs endow the endogenous EP4 receptor on macrophages with the ability to couple to Gi-type G-proteins, which converts the EP4 receptor on macrophages from an anti-phagocytotic receptor to one increasing phagocytosis, a central mechanism of the pro-resolving activity of synthetic SPMs. In the absence of the EP4 receptor, SPMs lose their anti-inflammatory and pro-resolving activity in vitro and in vivo. Our findings reveal an unusual mechanism of allosteric receptor modulation by lipids and provide a mechanism by which synthetic SPMs exert pro-resolving and anti-inflammatory effects, which may facilitate approaches to treat inflammation.

The Link between Inflammation, Lipid Derivatives, and Microbiota Metabolites in COVID-19 Patients: Implications on Eating Behaviors and Nutritional Status

Extreme inflammation that continues even after infections can lead to a cytokine storm. In recent times, one of the most common causes of cytokine storm activation has been SARS-CoV-2 infection. A cytokine storm leads to dysregulation and excessive stimulation of the immune system, producing symptoms typical of post-COVID syndrome, including chronic fatigue, shortness of breath, joint pain, trouble concentrating (known as "brain fog"), and even direct organ damage in the heart, lungs, kidneys, and brain. This work summarizes the current knowledge regarding inflammation and the cytokine storm related to SARS-CoV-2 infection. Additionally, changes in lipid metabolism and microbiota composition under the influence of inflammation in COVID-19, along with the possible underlying mechanisms, are described. Finally, this text explores potential health implications related to changes in eating behaviors and nutritional status in COVID-19 patients. Although research on the cytokine storm is still ongoing, there is convincing evidence suggesting that severe immune and inflammatory responses during the acute phase of COVID-19 may lead to long-term health consequences. Understanding these links is key to developing treatment strategies and supporting patients after infection.

Bile Acids as Emerging Players at the Intersection of Steatotic Liver Disease and Cardiovascular Diseases

Affecting approximately 25% of the global population, steatotic liver disease (SLD) poses a significant health concern. SLD ranges from simple steatosis to metabolic dysfunction-associated steatohepatitis and fibrosis with a risk of severe liver complications such as cirrhosis and hepatocellular carcinoma. SLD is associated with obesity, atherogenic dyslipidaemia, and insulin resistance, increasing cardiovascular risks. As such, identifying SLD is vital for cardiovascular disease (CVD) prevention and treatment. Bile acids (BAs) have critical roles in lipid digestion and are signalling molecules regulating glucose and lipid metabolism and influencing gut microbiota balance. BAs have been identified as critical mediators in cardiovascular health, influencing vascular tone, cholesterol homeostasis, and inflammatory responses. The cardio-protective or harmful effects of BAs depend on their concentration and composition in circulation. The effects of certain BAs occur through the activation of a group of receptors, which reduce atherosclerosis and modulate cardiac functions. Thus, manipulating BA receptors could offer new avenues for treating not only liver diseases but also CVDs linked to metabolic dysfunctions. In conclusion, this review discusses the intricate interplay between BAs, metabolic pathways, and hepatic and extrahepatic diseases. We also highlight the necessity for further research to improve our understanding of how modifying BA characteristics affects or ameliorates disease.

Implementation of multiomic mass spectrometry approaches for the evaluation of human health following environmental exposure

Omics analyses collectively refer to the possibility of profiling genetic variants, RNA, epigenetic markers, proteins, lipids, and metabolites. The most common analytical approaches used for detecting molecules present within biofluids related to metabolism are vibrational spectroscopy techniques, represented by infrared, Raman, and nuclear magnetic resonance (NMR) spectroscopies and mass spectrometry (MS). Omics-based assessments utilizing MS are rapidly expanding and being applied to various scientific disciplines and clinical settings. Most of the omics instruments are operated by specialists in dedicated laboratories; however, the development of miniature portable omics has made the technology more available to users for field applications. Variations in molecular information gained from omics approaches are useful for evaluating human health following environmental exposure and the development and progression of numerous diseases. As MS technology develops so do statistical and machine learning methods for the detection of molecular deviations from personalized metabolism, which are correlated to altered health conditions, and they are intended to provide a multi-disciplinary overview for researchers interested in adding multiomic analysis to their current efforts. This includes an introduction to mass spectrometry-based omics technologies, current state-of-the-art capabilities and their respective strengths and limitations for surveying molecular information. Furthermore, we describe how knowledge gained from these assessments can be applied to personalized medicine and diagnostic strategies.

Differential Impact In Vivo of Pf4-ΔCre-Mediated and Gp1ba-ΔCre-Mediated Depletion of Cyclooxygenase-1 in Platelets in Mice

BACKGROUND

Low-dose aspirin is widely used for the secondary prevention of cardiovascular disease. The beneficial effects of low-dose aspirin are attributable to its inhibition of platelet Cox (cyclooxygenase)-1-derived thromboxane A2. Until recently, the use of the Pf4 (platelet factor 4) Cre has been the only genetic approach to generating megakaryocyte/platelet ablation of Cox-1 in mice. However, Pf4-ΔCre displays ectopic expression outside the megakaryocyte/platelet lineage, especially during inflammation. The use of the Gp1ba (glycoprotein 1bα) Cre promises a more specific, targeted approach.

METHODS

To evaluate the role of Cox-1 in platelets, we crossed Pf4-ΔCre or Gp1ba-ΔCre mice with Cox-1flox/flox mice to generate platelet Cox-1-/- mice on normolipidemic and hyperlipidemic (Ldlr-/-; low-density lipoprotein receptor) backgrounds.

RESULTS

Ex vivo platelet aggregation induced by arachidonic acid or adenosine diphosphate in platelet-rich plasma was inhibited to a similar extent in Pf4-ΔCre Cox-1-/-/Ldlr-/- and Gp1ba-ΔCre Cox-1-/-/Ldlr-/- mice. In a mouse model of tail injury, Pf4-ΔCre-mediated and Gp1ba-ΔCre-mediated deletions of Cox-1 were similarly efficient in suppressing platelet prostanoid biosynthesis. Experimental thrombogenesis and attendant blood loss were similar in both models. However, the impact on atherogenesis was divergent, being accelerated in the Pf4-ΔCre mice while restrained in the Gp1ba-ΔCres. In the former, accelerated atherogenesis was associated with greater suppression of PGI2 biosynthesis, a reduction in the lipopolysaccharide-evoked capacity to produce PGE2 (prostaglandin E) and PGD2 (prostanglandin D), activation of the inflammasome, elevated plasma levels of IL-1β (interleukin), reduced plasma levels of HDL-C (high-density lipoprotein receptor-cholesterol), and a reduction in the capacity for reverse cholesterol transport. By contrast, in the latter, plasma HDL-C and α-tocopherol were elevated, and MIP-1α (macrophage inflammatory protein-1α) and MCP-1 (monocyte chemoattractant protein 1) were reduced.

CONCLUSIONS

Both approaches to Cox-1 deletion similarly restrain thrombogenesis, but a differential impact on Cox-1-dependent prostanoid formation by the vasculature may contribute to an inflammatory phenotype and accelerated atherogenesis in Pf4-ΔCre mice.

The calcineurin-NFATc pathway modulates the lipid mediators in BAL fluid extracellular vesicles, thereby regulating microvascular endothelial cell barrier function

Extracellular vesicles mediate intercellular communication by transporting biologically active macromolecules. Our prior studies have demonstrated that the nuclear factor of activated T cell cytoplasmic member 3 (NFATc3) is activated in mouse pulmonary macrophages in response to lipopolysaccharide (LPS). Inhibition of NFATc3 activation by a novel cell-permeable calcineurin peptide inhibitor CNI103 mitigated the development of acute lung injury (ALI) in LPS-treated mice. Although pro-inflammatory lipid mediators are known contributors to lung inflammation and injury, it remains unclear whether the calcineurin-NFATc pathway regulates extracellular vesicle (EV) lipid content and if this content contributes to ALI pathogenesis. In this study, EVs from mouse bronchoalveolar lavage fluid (BALF) were analyzed for their lipid mediators by liquid chromatography in conjunction with mass spectrometry (LC-MS/MS). Our data demonstrate that EVs from LPS-treated mice contained significantly higher levels of arachidonic acid (AA) metabolites, which were found in low levels by prior treatment with CNI103. The catalytic activity of lung tissue cytoplasmic phospholipase A2 (cPLA2) increased during ALI, correlating with an increased amount of arachidonic acid (AA) in the EVs. Furthermore, ALI is associated with increased expression of cPLA2, cyclooxygenase 2 (COX2), and lipoxygenases (5-LOX, 12-LOX, and 15-LOX) in lung tissue, and pretreatment with CNI103 inhibited the catalytic activity of cPLA2 and the expression of cPLA2, COX, and LOX transcripts. Furthermore, co-culture of mouse pulmonary microvascular endothelial cell (PMVEC) monolayer and NFAT-luciferase reporter macrophages with BALF EVs from LPS-treated mice increased the pulmonary microvascular endothelial cell (PMVEC) monolayer barrier permeability and luciferase activity in macrophages. However, EVs from CNI103-treated mice had no negative impact on PMVEC monolayer barrier integrity. In summary, BALF EVs from LPS-treated mice carry biologically active NFATc-dependent, AA-derived lipids that play a role in regulating PMVEC monolayer barrier function.

Roles of glutamic pyruvate transaminase 2 in reprogramming of airway epithelial lipidomic and metabolomic profiles after smoking

Metabolic abnormalities represent one of the pathological features of chronic obstructive pulmonary disease (COPD). Glutamic pyruvate transaminase 2 (GPT2) is involved in glutamate metabolism and lipid synthesis pathways, whilst the exact roles of GPT2 in the occurrence and development of COPD remains uncertain. This study aims at investigating how GPT2 and the associated genes modulate smoking-induced airway epithelial metabolism and damage by reprogramming lipid synthesis. The circulating or human airway epithelial metabolomic and lipidomic profiles of COPD patients or cell-lines explored with smoking were assessed to elucidate the pivotal roles of GPT2 in reprogramming processes. We found that GPT2 regulate the reprogramming of lipid metabolisms caused by smoking, especially phosphatidylcholine (PC) and triacylglycerol (TAG), along with changes in the expression of lipid metabolism-associated genes. GPT2 modulated cell sensitivities and survival in response to smoking by enhancing mitochondrial functions and maintaining lipid and energy homeostasis. Our findings provide evidence for the involvement of GPT2 in the reprogramming of airway epithelial lipids following smoking, as well as the molecular mechanisms underlying GPT2-mediated regulation, which may offer an alternative of therapeutic strategies for chronic lung diseases.

Investigation of Serum Endocan Levels in SARS-CoV-2 Patients

Endocan is an endothelial-cell-specific proteoglycan (ESM-1) and has emerged as an endothelial dysfunction and inflammatory marker in recent years. Endocan can be used as a marker of inflammatory endothelial dysfunction in endothelium-dependent disease: cardiovascular disease, sepsis, lung and kidney disease and malignancies. Recent data suggest that endothelial dysfunction is a key mechanism in COVID-19 pathogenesis. Endotheliitis and thrombo-inflammation are associated with severe forms of SARS-CoV-2 infection, and endocan is currently under investigation as a potential diagnostic and prognostic marker. The aim of this study was to determine serum endocan levels in patients with COVID-19 to evaluate the correlation between endocan levels and clinical disease diagnosis and prognosis. This study enrolled 56 patients, divided into three groups depending on disease severity: mild (15), moderate (25) and severe (16). The biochemical, demographic, clinical and imagistic data were collected and evaluated in correlation with the endocan levels. Serum endocan levels were significantly higher in the COVID-19 patients compared to the control group; also, endocan concentration correlated with vaccination status. The results revealed significantly elevated serum endocan levels in COVID-19 patients compared to the control group, with a correlation observed between endocan concentration and vaccination status. These findings suggest that endocan may serve as a novel biomarker for detecting inflammation and endothelial dysfunction risk in COVID-19 patients. There was no significant relationship between serum endocan levels and disease severity or the presence of cardiovascular diseases. Endocan can be considered a novel biomarker for the detection of inflammation and endothelial dysfunction risk in COVID-19 patients.