New therapeutic horizons for plasma phospholipid transfer protein (PLTP): Targeting endotoxemia, infection and sepsis

S100A8/A9hi neutrophils induce mitochondrial dysfunction and PANoptosis in endothelial cells via mitochondrial complex I deficiency during sepsis

S100a8/a9, largely released by polymorphonuclear neutrophils (PMNs), belongs to the S100 family of calcium-binding proteins and plays a role in a variety of inflammatory diseases. Although S100a8/a9 has been reported to trigger endothelial cell apoptosis, the mechanisms of S100a8/a9-induced endothelial dysfunction during sepsis require in-depth research. We demonstrate that high expression levels of S100a8/a9 suppress Ndufa3 expression in mitochondrial complex I via downregulation of Nrf1 expression. Mitochondrial complex I deficiency contributes to NAD+-dependent Sirt1 suppression, which induces mitochondrial disorders, including excessive fission and blocked mitophagy, and mtDNA released from damaged mitochondria ultimately activates ZBP1-mediated PANoptosis in endothelial cells. Moreover, based on comprehensive scRNA-seq and bulk RNA-seq analyses, S100A8/A9hi neutrophils are closely associated with the circulating endothelial cell count (a useful marker of endothelial damage), and S100A8 is an independent risk factor for poor prognosis in sepsis patients.

Risk factors and prognostic value of endotoxemia in patients with acute myocardial infarction

Background

There is increasing evidence regarding the association between endotoxemia and the pathogenesis of atherosclerosis and myocardial infarction (MI). During the acute phase of MI, endotoxemia might increase inflammation and drive adverse cardiovascular (CV) outcomes. We aimed to explore the risk factors and prognostic value of endotoxemia in patients admitted for acute MI.

Methods

Patients admitted to the coronary care unit of Dijon University Hospital for type 1 acute MI between 2013 and 2015 were included. Endotoxemia, assessed by plasma lipopolysaccharide (LPS) concentration, was measured by mass spectrometry. Major adverse CV events were recorded in the year following hospital admission.

Results

Data from 245 consecutive MI patients were analyzed. LPS concentration at admission markedly increased with age and diabetes. High LPS concentration was correlated with metabolic biomarkers (glycemia, triglyceride, and total cholesterol) but not with CV (troponin Ic peak and N-terminal pro-brain natriuretic peptide) or inflammatory biomarkers (C-reactive protein, IL6, IL8, and TNFα). LPS concentration was not associated with in-hospital or 1-year outcomes.

Conclusions

In patients admitted for MI, higher levels of endotoxins were related to pre-existing conditions rather than acute clinical severity. Therefore, endotoxins measured on the day of MI could reflect metabolic chronic endotoxemia rather than MI-related acute gut translocation.

High-Density Lipoprotein Subfractions Remodeling: A Critical Process for the Treatment of Atherosclerotic Cardiovascular Diseases

Numerous studies have shown that a low level of high-density lipoprotein cholesterol (HDL-C) is an independent biomarker of cardiovascular disease. High-density lipoprotein (HDL) is considered to be a protective factor for atherosclerosis (AS). Therefore, raising HDL-C has been widely recognized as a promising strategy to treat atherosclerotic cardiovascular diseases (ASCVD). However, several studies have found that increasing HDL-C levels does not necessarily reduce the risk of ASCVD. HDL particles are highly heterogeneous in structure, composition, and biological function. Moreover, HDL particles from atherosclerotic patients exhibit impaired anti-atherogenic functions and these dysfunctional HDL particles might even promote ASCVD. This makes it uncertain that HDL-raising therapy will prevent and treat ASCVD. It is necessary to comprehensively analyze the structure and function of HDL subfractions. We review current advances related to HDL subfractions remodeling and highlight how current lipid-modifying drugs such as niacin, statins, fibrates, and cholesteryl ester transfer protein inhibitors regulate cholesterol concentration of HDL and specific HDL subfractions.

The Effect of Enteric-Derived Lipopolysaccharides on Obesity

Endotoxin is a general term for toxic substances in Gram-negative bacteria, whose damaging effects are mainly derived from the lipopolysaccharides (LPS) in the cell walls of Gram-negative bacteria, and is a strong pyrogen. Obesity is a chronic, low-grade inflammatory condition, and LPS are thought to trigger and exacerbate it. The gut flora is the largest source of LPS in the body, and it is increasingly believed that altered intestinal microorganisms can play an essential role in the pathology of different diseases. Today, the complex axis linking gut flora to inflammatory states and adiposity has not been well elucidated. This review summarises the evidence for an interconnection between LPS, obesity, and gut flora, further expanding our understanding of LPS as a mediator of low-grade inflammatory disease and contributing to lessening the effects of obesity and related metabolic disorders. As well as providing targets associated with LPS, obesity, and gut flora, it is hoped that interventions that combine targets with gut flora address the individual differences in gut flora treatment.

The role of genetically-influenced phospholipid transfer protein activity in lipoprotein metabolism and coronary artery disease

BACKGROUND

Phospholipid transfer protein (PLTP) transfers surface phospholipids between lipoproteins and as such plays a role in lipoprotein metabolism, but with unclear effects on coronary artery disease (CAD) risk. We aimed to investigate the associations of genetically-influenced PLTP activity with 1-H nuclear magnetic resonance (1H-NMR) metabolomic measures and with CAD. Furthermore, using factorial Mendelian randomization (MR), we examined the potential additional effect of genetically-influenced PLTP activity on CAD risk on top of genetically-influenced low-density lipoprotein-cholesterol (LDL-C) lowering.

METHODS

Using data from UK Biobank, genetic scores for PLTP activity and LDL-C were calculated and dichotomised based on the median, generating four groups with combinations of high/low PLTP activity and high/low LDL-C levels for the factorial MR. Linear and logistic regressions were performed on 168 metabolomic measures (N = 58,514) and CAD (N = 318,734, N-cases=37,552), respectively, with results expressed as β coefficients (in standard deviation units) or odds ratios (ORs) and 95% confidence interval (CI).

RESULTS

Irrespective of the genetically-influenced LDL-C, genetically-influenced low PLTP activity was associated with a higher HDL particle concentration (β [95% CI]: 0.03 [0.01, 0.05]), smaller HDL size (-0.14 [-0.15, -0.12]) and higher triglyceride (TG) concentration (0.04 [0.02, 0.05]), but not with CAD (OR 0.99 [0.97, 1.02]). In factorial MR analyses, genetically-influenced low PLTP activity and genetically-influenced low LDL-C had independent associations with metabolomic measures, and genetically-influenced low PLTP activity did not show an additional effect on CAD risk.

CONCLUSIONS

Low PLTP activity associates with higher HDL particle concentration, smaller HDL particle size and higher TG concentration, but no association with CAD risk was observed.

Phospholipid transfer protein ameliorates sepsis-induced cardiac dysfunction through NLRP3 inflammasome inhibition

Cardiomyocyte pyroptosis is a primary contributor to sepsis-induced cardiac dysfunction (SICD). Recombinant phospholipid transfer protein (PLTP) have been demonstrated to possess anti-inflammatory and antiseptic properties. However, the effect of PLTP on SICD remains unknown. In this study, we established the in vivo and in vitro sepsis model with the recombinant PLTP treatment. The survival rates of mice, mouse cardiac function, cell viability, the protein level of proinflammatory cytokine, and lactate dehydrogenase level were evaluated. The cardiomyocyte pyroptotic changes were observed. The distribution of PLTP and NOD-like receptor thermal protein domain associated protein 3 (NLRP3) in mouse myocardial tissue and expression of PLTP, apoptosis associated speck like protein containing a CARD (ASC), NLRP3, caspase-1, interleukin (IL)-1β, and Gasdermin D (GSDMD) were detected. PLTP ameliorated the cecal ligation and puncture-induced mouse survival rate decrease and cardiac dysfunction, inhibited the IL-1β, IL-18, and tumor necrosis factor (TNF)-α release, and blocked the NLRP3 inflammasome/GSDMD signaling pathway in septic mice. In vitro, PLTP reversed the lipopolysaccharide-induced cardiomyocyte pyroptosis, expression of IL-1β, IL-6, TNF-α, and activation of the NLRP3 inflammasome/GSDMD signal pathway. Moreover, PLTP could bind to NLRP3 and negatively regulate the activity of the NLRP3 inflammasome/GSDMD signal pathway. This study demonstrated that PLTP can ameliorate SICD by inhibiting inflammatory responses and cardiomyocyte pyroptosis by blocking the activation of the NLRP3 inflammasome/GSDMD signaling pathway.

Plasma citrulline concentration and plasma LPS detection among critically ill patients a prospective observational study

PURPOSE

Gut can be a source of sepsis but sepsis itself can induce gut dysfunction. We aimed to study whether plasma citrulline, a marker of enterocyte mass, was correlated with plasma lipopolysaccharide, a potential marker of bacterial translocation among critically ill patients.

MATERIALS AND METHODS

Critically ill patients admitted to the ICU. Plasma citrulline and plasma LPS concentration and activity were measured at ICU admission. Patients were compared according to the presence of sepsis at ICU admission.

RESULTS

109 critically ill patients, with SOFA score 8 [6-12], were prospectively included. Sixty six patients (61%) had sepsis at ICU admission. There was no correlation between plasma citrulline concentration and plasma LPS concentration or activity. However, sepsis at ICU admission was associated with a lower plasma citrulline concentration (13.4 μmol.L-1 vs 21.3 μmol.L-1, p = 0.02). Plasma LPS activity was significantly higher among patients with abdominal sepsis compared to patients with extra-abdominal sepsis (1.04 EU/mL vs 0.63, p = 0.01).

CONCLUSIONS

Plasma citrulline is not associated with the level of plasma LPS but is strongly decreased among septic patients. Detection of LPS is ubiquitous among critically ill patients but abdominal sepsis is associated with increased plasma LPS activity compared to extra-abdominal sepsis.

Lactobacillus acidophilus JYLA-126 Ameliorates Obesity-Associated Metabolic Disorders by Positively Regulating the AMPK Signaling Pathway Through the Gut-Liver Axis

Obesity is a chronic metabolic disease worldwide and is considered a major health problem in contemporary society. Lactobacillus acidophilus have demonstrated beneficial effects on obesity, but the specific mechanism of how it exerts beneficial effects has not been elucidated. Here, we found that L. acidophilus JYLA-126 had good biological properties for intestinal health, such as antioxidation, acid tolerance, bile salt tolerance, antimicrobial activity, and gut colonization. We further identified that supplementation of L. acidophilus JYLA-126 obese mice possessed a dose-dependent amelioration of body weight, intestinal imbalance, and metabolic disorders compared to HFD-induced mice. Mechanistically, the excellent slimming effect of L. acidophilus JYLA-126 was achieved mainly by reversing HFD-induced gut dysbiosis, inhibiting inflammatory factors and balancing the homeostasis of the gut-liver axis. Specifically, L. acidophilus JYLA-126 improved hepatic glycogen synthesis, lowered oxidative stress, and facilitated lipid metabolism by regulating AMPK signaling pathway-related protein expression to restore the overall metabolic level. Accordingly, L. acidophilus JYLA-126 promoted energy uptake efficiency in obese mice, resulting in significant expression of uncoupling protein 1 (UCP1) protein in brown adipose tissue (BAT), and markedly reduced the size of adipocytes. These findings indicate that the anti-obesity activity of L. acidophilus JYLA-126 correlates with activation of the AMPK signaling pathway through improved gut-liver interactions.

Cytokine dysregulation despite immunoglobulin replacement therapy in common variable immunodeficiency (CVID)

Introduction

Common variable immunodeficiency (CVID) is the most prevalent symptomatic primary immunodeficiency. CVID is a heterogeneous disorder with a presumed multifactorial etiology. Intravenous or subcutaneous immunoglobulin replacement therapy (IgRT) can prevent severe infections but not underlying immune dysregulation.

Methods

In this study, we evaluated the serum concentrations of proinflammatory (TNF-α, IL-1β, IL-6) and immunoregulatory cytokines (IL-10), as well as lipopolysaccharide (LPS) and soluble CD14 (sCD14) in CVID individuals with infectious only (INF-CVID), and those with additional systemic autoimmune and inflammatory disorders (NIC-CVID), and healthy donors (HD).

Results

Our results showed increased serum concentrations of TNF-α, IL-1β, IL-6, and IL-10 in both INF-CVID and NIC-CVID subjects compared to HD. However, elevations of TNF-α, IL-1β, IL-6, and IL-10 were significantly more marked in NIC-CVID than INF-CVID. Additionally, LPS concentrations were increased only in NIC-CVID but not in INF-CVID compared to HD. Circulating levels of sCD14 were significantly increased in NIC-CVID compared to both INF-CVID and HD.

Discussion

These findings indicate persistent cytokine dysregulation despite IgRT in individuals with CVID. Moreover, the circulating cytokine profile reveals the heterogeneity of immune dysregulation in different subgroups of CVID subjects.

Endotoxemia in Acute Heart Failure and Cardiogenic Shock: Evidence, Mechanisms and Therapeutic Options

Acute heart failure and cardiogenic shock are frequently occurring and deadly conditions. In patients with those conditions, endotoxemia related to gut injury and gut barrier dysfunction is usually described as a driver of organ dysfunction. Because endotoxemia might reciprocally alter cardiac function, this phenomenon has been suggested as a potent vicious cycle that worsens organ perfusion and leading to adverse outcomes. Yet, evidence beyond this phenomenon might be overlooked, and mechanisms are not fully understood. Subsequently, even though therapeutics available to reduce endotoxin load, there are no indications to treat endotoxemia during acute heart failure and cardiogenic shock. In this review, we first explore the evidence regarding endotoxemia in acute heart failure and cardiogenic shock. Then, we describe the main treatments for endotoxemia in the acute setting, and we present the challenges that remain before personalized treatments against endotoxemia can be used in patients with acute heart failure and cardiogenic shock.

Plasma Proteomics Unveil Novel Immune Signatures and Biomarkers upon SARS-CoV-2 Infection

Several elements have an impact on COVID-19, including comorbidities, age and sex. To determine the protein profile changes in peripheral blood caused by a SARS-CoV-2 infection, a proximity extension assay was used to quantify 1387 proteins in plasma samples among 28 Finnish patients with COVID-19 with and without comorbidities and their controls. Key immune signatures, including CD4 and CD28, were changed in patients with comorbidities. Importantly, several unreported elevated proteins in patients with COVID-19, such as RBP2 and BST2, which show anti-microbial activity, along with proteins involved in extracellular matrix remodeling, including MATN2 and COL6A3, were identified. RNF41 was downregulated in patients compared to healthy controls. Our study demonstrates that SARS-CoV-2 infection causes distinct plasma protein changes in the presence of comorbidities despite the interpatient heterogeneity, and several novel potential biomarkers associated with a SARS-CoV-2 infection alone and in the presence of comorbidities were identified. Protein changes linked to the generation of SARS-CoV-2-specific antibodies, long-term effects and potential association with post-COVID-19 condition were revealed. Further study to characterize the identified plasma protein changes from larger cohorts with more diverse ethnicities of patients with COVID-19 combined with functional studies will facilitate the identification of novel diagnostic, prognostic biomarkers and potential therapeutic targets for patients with COVID-19.

The emerging roles of leukocyte cell-derived chemotaxin-2 in immune diseases: From mechanisms to therapeutic potential

Leukocyte cell-derived chemotaxin-2 (LECT2, also named ChM-II), initially identified as a chemokine mediating neutrophil migration, is a multifunctional secreted factor involved in diverse physiological and pathological processes. The high sequence similarity of LECT2 among different vertebrates makes it possible to explore its functions by using comparative biology. LECT2 is associated with many immune processes and immune-related diseases via its binding to cell surface receptors such as CD209a, Tie1, and Met in various cell types. In addition, the misfolding LECT2 leads to the amyloidosis of several crucial tissues (kidney, liver, and lung, etc.) by inducing the formation of insoluble fibrils. However, the mechanisms of LECT2-mediated diverse immune pathogenic conditions in various tissues remain to be fully elucidated due to the functional and signaling heterogeneity. Here, we provide a comprehensive summary of the structure, the “double-edged sword” function, and the extensive signaling pathways of LECT2 in immune diseases, as well as the potential applications of LECT2 in therapeutic interventions in preclinical or clinical trials. This review provides an integrated perspective on the current understanding of how LECT2 is associated with immune diseases, with the aim of facilitating the development of drugs or probes against LECT2 for the theranostics of immune-related diseases.

Ginkgolic acid promotes inflammation and macrophage apoptosis via SUMOylation and NF-κB pathways in sepsis

Background

Excessive inflammation and increased apoptosis of macrophages contribute to organ damage and poor prognosis of sepsis. Ginkgolic acid (GA) is a natural constituent extracted from the leaves of Ginkgo biloba, that can regulate inflammation and apoptosis. The present study aims to investigate the potential effect of GA in treating sepsis and its possible mechanisms.

Materials and methods

Here, a classic septic mice model and a lipopolysaccharide (LPS)-induced RAW 264.7 inflammation model were established. Cytokines in serum and culture supernatant were detected by ELISA, and the mRNA levels of them were examined by PCR. Hematoxylin and eosin (H&E) staining was performed to determine histopathological changes in liver, lung and kidney. Bacterial burden in the blood, peritoneal lavage fluids (PLFs) and organs were observed on Luria-Bertani agar medium. Flow cytometry and western blotting was used to detect apoptosis and the expression level of apoptosis related molecules, respectively. Moreover, the levels of SUMOylation were detected by western blotting. The activity of NF-κB p65 was assessed by immunofluorescence staining and western blotting.

Results

The result showed that GA promoted inflammatory responses, reduced bacterial clearance, aggravated organ damage, and increased mortality in septic mice. GA increased apoptosis in peritoneal macrophages (PMs) and RAW 264.7 cells. Meanwhile, GA inhibited SUMOylation and increased the nuclear translocation of NF-κB p65 as well as its phosphorylation level.

Conclusion

Collectively, GA promotes inflammation and macrophage apoptosis in sepsis, which may be mediated by inhibiting the SUMOylation process and increasing NF-κB p65 activity.

Rheumatoid arthritis is associated with increased gut permeability and bacterial translocation which are reversed by inflammation control

OBJECTIVE

to assess how rheumatoid arthritis (RA) and Disease Modifying Anti Rheumatic Drugs (DMARDs) affect gut permeability.

METHODS

to explore colonic mucosa integrity, tight junction proteins ZO-1, occludin and claudin 2 were quantified by immunohistochemistry on colonic biopsies in 20 RA patients and 20 age- and sex-matched controls. Staining intensity was assessed by two blinded independent readers. To explore intestinal permeability, serum concentrations of LPS-binding protein (LBP), sCD14 and zonulin-related proteins (ZRP) were evaluated by ELISA in another cohort of 59 RA: 21 patients naive of DMARDs (17 before and after introduction of a conventional synthetic (cs) DMARDs), 38 patients with severe RA (before and after introduction of a biological (b) DMARDs), and 33 healthy controls.

RESULTS

Z0-1 protein was less expressed in colon of RA patients than controls (mean score ± SEM of 1.6 ± 0.56 vs 2.0 ± 0.43; p= 0.01), while no significant difference was detected for occludin and claudin-2. RA patients had higher serum LBP and sCD14 concentrations than controls. LBP and sCD14 levels were significantly correlated with DAS28 (r = 0.61, p= 0.005 and r = 0.57, p= 0.01, respectively) while ZRP did not. bDMARD responders had significantly reduced LBP and sCD14 concentrations unlike bDMARDs non-responders and patients treated with csDMARDs.

CONCLUSION

RA patients have altered colonic tight junction proteins and increased serum biomarkers of intestinal permeability. There was a correlation between serological markers of intestinal permeability and disease activity as well as bDMARD response. These results suggest a link between impaired gut integrity and systemic inflammation in RA.

Effect of a Functional Phospholipid Metabolome-Protein Association Pathway on the Mechanism of COVID-19 Disease Progression

This study aimed to explore the clinical practice of phospholipid metabolic pathways in COVID-19. In this study, 48 COVID-19 patients and 17 healthy controls were included. Patients were divided into mild (n=40) and severe (n=8) according to their severity. Phospholipid metabolites, TCA circulating metabolites, eicosanoid metabolites, and closely associated enzymes and transfer proteins were detected in the plasma of all individuals using metabolomics and proteomics assays, respectively. 30 of the 33 metabolites found differed significantly (P<0.05) between patients and healthy controls (P<0.05), with D-dimmer significantly correlated with all of the lysophospholipid metabolites (LysoPE, LysoPC, LysoPI and LPA). In particular, we found that phosphatidylinositol (PI) and phosphatidylcholine (PC) could identify patients from healthy controls (AUC 0.771 and 0.745, respectively) and that the severity of the patients could be determined (AUC 0.663 and 0.809, respectively). The last measurement before discharge also revealed significant changes in both PI and PC. For the first time, our study explores the significance of the phospholipid metabolic system in COVID-19 patients. Based on molecular pathway mechanisms, three important phospholipid pathways related to Ceramide-Malate acid (Cer-SM), Lysophospholipid (LPs), and membrane function were established. Clinical values discovered included the role of Cer in maintaining the inflammatory internal environment, the modulation of procoagulant LPA by upstream fibrinolytic metabolites, and the role of PI and PC in predicting disease aggravation.

Mettl14 mediates the inflammatory response of macrophages in atherosclerosis through the NF-κB/IL-6 signaling pathway

The inflammatory response of macrophages has been reported to play a critical role in atherosclerosis. The inflammatory state of macrophages is modified by epigenetic reprogramming. m⁶A RNA methylation is an epigenetic modification of RNAs. However, little is known about the potential roles and underlying mechanisms of m⁶A modification in macrophage inflammation. Herein, we showed that the expression of the m⁶A modification “writer” Mettl14 was increased in coronary heart disease and LPS-stimulated THP-1 cells. Knockdown of Mettl14 promoted M2 polarization of macrophages, inhibited foam cell formation and decreased migration. Mechanistically, the expression of Myd88 and IL-6 was decreased in Mettl14 knockdown cells. Through m⁶A modification, Mettl14 regulated the stability of Myd88 mRNA. Furthermore, Myd88 affected the transcription of IL-6 via the distribution of p65 in nuclei rather than directly regulating the expression of IL-6 through m⁶A modification. In vivo, Mettl14 gene knockout significantly reduced the inflammatory response of macrophages and the development of atherosclerotic plaques. Taken together, our data demonstrate that Mettl14 plays a vital role in macrophage inflammation in atherosclerosis via the NF-κB/IL-6 signaling pathway, suggesting that Mettl14 may be a promising therapeutic target for the clinical treatment of atherosclerosis.