LTB4 and 5-oxo-ETE from extracellular vesicles stimulate neutrophils in granulomatosis with polyangiitis

The mitochondrial biliverdin exporter ABCB10 in hepatocytes mitigates neutrophilic inflammation in alcoholic hepatitis

Acute liver failure caused by alcoholic hepatitis (AH) is only effectively treated with liver transplantation. Livers of patients with AH show a unique molecular signature characterized by defective hepatocellular redox metabolism, concurrent to hepatic infiltration of neutrophils that express myeloperoxidase (MPO) and form neutrophil extracellular traps (NETs). Exacerbated NET formation and MPO activity contribute to liver damage in mice with AH and predicts poor prognosis in AH patients. The identification of pathways that maladaptively exacerbate neutrophilic activity in liver could inform of novel therapeutic approaches to treat AH. Whether the redox defects of hepatocytes in AH directly exacerbate neutrophilic inflammation and NET formation is unclear. Here we identify that the protein content of the mitochondrial biliverdin exporter ABCB10, which increases hepatocyte-autonomous synthesis of the ROS-scavenger bilirubin, is decreased in livers from humans and mice with AH. Increasing ABCB10 expression selectively in hepatocytes of mice with AH is sufficient to decrease MPO gene expression and histone H3 citrullination, a specific marker of NET formation. These anti-inflammatory effects can be explained by ABCB10 function reducing ROS-mediated actions in liver. Accordingly, ABCB10 gain-of-function selectively increased the mitochondrial GSH/GSSG ratio and decreased hepatic 4-HNE protein adducts, without elevating mitochondrial fat expenditure capacity, nor mitigating steatosis and hepatocyte death. Thus, our study supports that ABCB10 function regulating ROS-mediated actions within surviving hepatocytes mitigates the maladaptive activation of infiltrated neutrophils in AH. Consequently, ABCB10 gain-of-function in human hepatocytes could potentially decrease acute liver failure by decreasing the inflammatory flare caused by excessive neutrophil activity.

A randomized control trial to test the effect of pegbovigrastim treatment at dry off on plasma and milk oxylipid profiles during early mammary gland involution and post-parturient period

The early period of mammary gland involution is a critical juncture in the lactation cycle that can have significant effects on milk production and mammary gland health. Pegbovigrastim (PEG) administered 1 wk prior and on the day of parturition can enhance immune function and reduce the incidence of mastitis in the early postpartum period. Oxylipids are potent metabolites of polyunsaturated fatty acids (PUFA) and are important mediators of inflammation. The objective of this study was to evaluate effects of PEG given 1 wk before and at the day of dry-off (D0) on concentrations of oxylipids in plasma and milk from 7 d before D0 to 14 after, as well as the effects during the first 14 d of the subsequent lactation. We hypothesized that both pro- and anti-inflammatory oxylipids would vary based on initiation of mammary gland involution and that pegbovigrastim would affect oxylipid concentration, particularly those related to leukocytes. A complete randomized blocked design was used to enroll cows into either a PEG treatment group (n = 10) or control group (n = 10; CON). Blood samples were collected -7, -2, -1, 0, 1, 2, 4, 7, 14 d relative to dry-off and 5, 10, and 14 d post-calving. Samples were analyzed for PUFA and oxylipids in milk and plasma by ultra-performance mass-spectrometry and liquid chromatography tandem quadrupole mass spectrometry, respectively. Overall, 30 lipid mediators were measured both in milk and plasma. Repeated measures analyses revealed a significant interaction of treatment by time for milk 8-iso-keto-15-prostaglandin E2, prostaglandin F2α, plasma 8,12-iso-prostaglandin FαVI, 11-hydroxyeicosatetraenoic acid, and 12-hydroxyheptadecatienoic acid. The majority of milk PUFA and oxylipids differed significantly during early mammary gland involution and into the early postpartum period. This study demonstrated changes in oxylipids in milk secretions and plasma during early involution and further investigation may illuminate multiple complex processes and reveal targets for optimization of mammary gland involution.

Update of Potential Biomarkers in Risk Prediction and Monitoring of Atherosclerosis in Systemic Lupus Erythematosus to Prevent Cardiovascular Disease

Systemic lupus erythematosus is a chronic connective tissue disease associated with an increased risk of premature atherosclerosis. It is estimated that approximately 10% of SLE patients develop significant atherosclerosis each year, which is responsible for premature cardiovascular disease that is largely asymptomatic. This review summarizes the most recent reports from the past few years on biomarkers of atherosclerosis in SLE, mainly focusing on immune markers. Persistent chronic inflammation of the vascular wall is an important cause of cardiovascular disease (CVD) events related to endothelial dysfunction, cell proliferation, impaired production and function of nitric oxide and microangiopathic changes. Studies on pathogenic immune mediators involved in atherosclerosis will be crucial research avenues for preventing CVD.

NLRP3 is essential for neutrophil polarization and chemotaxis in response to leukotriene B4 gradient

Neutrophil recruitment to sites of infection and inflammation is an essential process in the early innate immune response. Upon activation, a subset of neutrophils rapidly assembles the multiprotein complex known as the NLRP3 inflammasome. The NLRP3 inflammasome forms at the microtubule organizing center, which promotes the formation of interleukin (IL)-1β and IL-18, essential cytokines in the immune response. We recently showed that mice deficient in NLRP3 (NLRP3-/-) have reduced neutrophil recruitment to the peritoneum in a model of thioglycolate-induced peritonitis. Here, we tested the hypothesis that this diminished recruitment could be, in part, the result of defects in neutrophil chemotaxis. We find that NLRP3-/- neutrophils show loss of cell polarization, as well as reduced directionality and velocity of migration toward increasing concentrations of leukotriene B4 (LTB4) in a chemotaxis assay in vitro, which was confirmed through intravital microscopy of neutrophil migration toward a laser-induced burn injury of the liver. Furthermore, pharmacologically blocking NLRP3 inflammasome assembly with MCC950 in vitro reduced directionality but preserved nondirectional movement, indicating that inflammasome assembly is specifically required for polarization and directional chemotaxis, but not cell motility per se. In support of this, pharmacological breakdown of the microtubule cytoskeleton via nocodazole treatment induced cell polarization and restored nondirectional cell migration in NLRP3-deficient neutrophils in the LTB4 gradient. Therefore, NLRP3 inflammasome assembly is required for establishment of cell polarity to guide the directional chemotactic migration of neutrophils.

Baseline Elevations of Leukotriene Metabolites and Altered Plasmalogens Are Prognostic Biomarkers of Plaque Progression in Systemic Lupus Erythematosus

Systemic lupus erythematosus (SLE) is associated with an increased incidence of acute and chronic cardiovascular disease as compared to the general population. This study uses a comprehensive metabolomic screen of baseline sera from lupus patients to identify metabolites that predict future carotid plaque progression, following 8–9 years of follow-up. Nine patients had SLE without plaque progression, 8 had SLE and went on to develop atherosclerotic plaques (SLE^PP), and 8 patients were controls who did not have SLE. The arachidonic acid pathway metabolites, leukotriene B4 (LTB4) and 5-hydroxyeicosatetraenoic acid (5-HETE), and the oxidized lipids 9/13-hydroxyoctodecadienoic acid (HODE) were found to be significantly altered (p < 0.05 and fold-change >2) in SLE^PP patients compared to SLE patients without plaque progression. SLE^PP patients also exhibited significantly altered levels of branched chain amino acid (BCAA) metabolites and plasmalogens compared to the non-SLE controls. Taken together with the rich literature on these metabolites, these findings suggest that the identified metabolites may not only be prognostic of cardiovascular disease development in SLE patients, but they may also be active drivers of atheroma formation. Early identification of these high risk SLE patients may help institute preventive measures early in the disease course.

Profile of circulating extracellular vesicles microRNA correlates with the disease activity in granulomatosis with polyangiitis

Granulomatosis with polyangiitis is a chronic systemic inflammation of small vessels characterized by circulating anti-proteinase 3 antibodies. MicroRNAs are short transcripts specifically inhibiting protein translation. Neutrophils can release extracellular vesicles (EVs). In this study, we characterized profile of microRNA trafficked by EVs in GPA. Fifty patients with GPA were enrolled in the study, 25 at acute phase and 25 in remission. EVs were isolated from the blood serum, characterized by their number, size distribution. Following unbiased screening for microRNA expression, differentially expressed candidates were measured by quantitative real-time PCR. Circulating DNA-myeloperoxidase complexes and apoptosis-related transcripts in peripheral blood neutrophils were quantified. We identified four differentially expressed microRNAs from EVs in granulomatosis with polyangiitis (GPA). MirRs-223-3p, 664a-3p, and 200b-3p were overexpressed and miR-769-5p suppressed in the disease. A distinction between GPA and healthy controls was the best for miR-223-3p, whereas miR-664a-3p discriminated between active vs. remission of GPA. Correct classification of the disease based on multivariate discriminant analysis was between 92% for acute phase and 85% for all study participants. Bioinformatics tools identified genes transcripts potentially targeted by the microRNAs belonging to pathways of focal adhesion, mTOR signaling and neutrophil extracellular traps formation. Two microRNAs positively correlating with the disease activity were involved in neutrophil extracellular traps formation and apoptosis inhibition. A comprehensive characteristics of microRNAs trafficked in bloodstream inside EVs correlates well with our understanding of the mechanisms of GPA and suggests the importance of EVs in progression of the disease.

Targeted Lipidomics for Characterization of PUFAs and Eicosanoids in Extracellular Vesicles

Lipids are increasingly recognized as bioactive mediators of extracellular vesicle (EV) functions. However, while EV proteins and nucleic acids are well described, EV lipids are insufficiently understood due to lack of adequate quantitative methods. We adapted an established targeted and quantitative mass spectrometry (LC-MS/MS) method originally developed for analysis of 94 eicosanoids and seven polyunsaturated fatty acids (PUFA) in human plasma. Additionally, the influence of freeze–thaw (FT) cycles, injection volume, and extraction solvent were investigated. The modified protocol was applied to lipidomic analysis of differently polarized macrophage-derived EVs. We successfully quantified three PUFAs and eight eicosanoids within EVs. Lipid extraction showed reproducible PUFA and eicosanoid patterns. We found a particularly high impact of FT cycles on EV lipid profiles, with significant reductions of up to 70%. Thus, repeated FT will markedly influence analytical results and may alter EV functions, emphasizing the importance of a standardized sample pretreatment protocol for the analysis of bioactive lipids in EVs. EV lipid profiles differed largely depending on the polarization of the originating macrophages. Particularly, we observed major changes in the arachidonic acid pathway. We emphasize the importance of a standardized sample pretreatment protocol for the analysis of bioactive lipids in EVs.

Lipidomic Analysis of Extracellular Vesicles Isolated from Human Plasma and Serum

Lipidomics is an omics approach to comprehensively study lipid profiles in biological samples, such as plasma, serum, urine, and tissue specimens. Moreover, lipidomic analyses are useful for identifying novel lipid biomarkers, especially for various metabolic and malignant diseases in humans. Extracellular vesicles (EVs) are lipid bilayer-encapsulated nanoparticles secreted from various cells into the extracellular space. In particular, circulating EVs in the blood stream have attracted considerable research interest as they are considered the fingerprint of the cells from which they are secreted and are a promising source for less-invasive biomarker screening. Here, we describe the entire workflow for the lipidomic analysis of circulating EVs, including the methods for their purification from human plasma and serum, liquid chromatography coupled with high-resolution mass spectrometry-based lipid measurement, and data analyses for profiling EV lipids. Using this methodological workflow, over 260 lipid molecules belonging to the glycerophospholipid and sphingolipid groups can be detected.

Recent advances in Extracellular Vesicles and their involvements in vasculitis

Systemic vasculitis is a heterogeneous group of multisystem autoimmune disorders characterized by inflammation of blood vessels. Although many progresses in diagnosis and immunotherapies have been achieved over the past decades, there are still many unanswered questions about vasculitis from pathological understanding to more advanced therapies. Extracellular vesicles (EVs) are double-layer phospholipid membrane vesicles harboring various cargoes. EVs can be classified into exosomes, microvesicles (MVs), and apoptotic bodies depending on their size and origin of cellular compartment. EVs can be released by almost all cell types and may be involved in physical and pathological processes including inflammation and autoimmune responses. In systemic vasculitis, EVs may have pathogenic involvement in inflammation, autoimmune responses, thrombosis, endothelium injury, angiogenesis and intimal hyperplasia. EV-associated redox reaction may also be involved in vasculitis pathogenesis by inducing inflammation, endothelial injury and thrombosis. Additionally, EVs may serve as specific biomarkers for diagnosis or monitoring of disease activity and therapeutic efficacy, i.e. AAV-associated renal involvement. In this review, we have discussed the recent advances of EVs, especially their roles in pathogenesis and clinical involvements in vasculitis.

Extracellular Vesicles Tune the Immune System in Renal Disease: A Focus on Systemic Lupus Erythematosus, Antiphospholipid Syndrome, Thrombotic Microangiopathy and ANCA-Vasculitis

Extracellular vesicles (EV) are microparticles released in biological fluids by different cell types, both in physiological and pathological conditions. Owing to their ability to carry and transfer biomolecules, EV are mediators of cell-to-cell communication and are involved in the pathogenesis of several diseases. The ability of EV to modulate the immune system, the coagulation cascade, the angiogenetic process, and to drive endothelial dysfunction plays a crucial role in the pathophysiology of both autoimmune and renal diseases. Recent studies have demonstrated the involvement of EV in the control of renal homeostasis by acting as intercellular signaling molecules, mediators of inflammation and tissue regeneration. Moreover, circulating EV and urinary EV secreted by renal cells have been investigated as potential early biomarkers of renal injury. In the present review, we discuss the recent findings on the involvement of EV in autoimmunity and in renal intercellular communication. We focused on EV-mediated interaction between the immune system and the kidney in autoimmune diseases displaying common renal damage, such as antiphospholipid syndrome, systemic lupus erythematosus, thrombotic microangiopathy, and vasculitis. Although further studies are needed to extend our knowledge on EV in renal pathology, a deeper investigation of the impact of EV in kidney autoimmune diseases may also provide insight into renal biological processes. Furthermore, EV may represent promising biomarkers of renal diseases with potential future applications as diagnostic and therapeutic tools.

Endothelial cells response to neutrophil-derived extracellular vesicles miRNAs in anti-PR3 positive vasculitis

In vasculitis disorders, inflammation affects blood vessels. Granulomatosis with polyangiitis (GPA) is a chronic systemic vasculitis distinguished by the presence of anti-proteinase-3 autoantibodies (anti-PR3). In this study we analyzed the molecular signature of human umbilical endothelial cells (HUVECs) in response to neutrophil-derived extracellular vesicles (EVs). EVs were obtained from anti-PR3-activated neutrophils, purified and characterized by flow cytometry, nanoparticle tracking and miRNA screening. HUVECs were stimulated with EVs and miRNA/mRNA expression was measured. Cell culture media proteins were identified by antibody microarrays and selected cytokines were measured. Comparison of differentially expressed miRNAs/mRNAs between non-stimulated and EV-stimulated HUVECs revealed two regulatory patterns. Significant up-regulation of 14 mRNA transcripts (including CXCL8, DKK1, IL1RL1, ANGPT-2, THBS1 and VCAM-1) was accompanied by 11 miRNAs silencing (including miR-661, miR-664a-3p, miR-377-3p, miR-30d-5p). Significant down-regulation was observed for nine mRNA transcripts (including FASLG, CASP8, STAT3, GATA3, IRAK1 and IL6) and accompanied by up-regulation of 10 miRNAs (including miR-223-3p, miR-142-3p, miR-211-5p). Stimulated HUVECs released IL-8, Dickkopf-related protein 1 (DKK-1), soluble interleukin (IL)-1 like receptor-1 (ST2), growth differentiation factor 15 (GDF-15), angiopoietin-2, endoglin, thrombospondin-1 and vascular adhesion molecule-1 (VCAM-1). Moreover, transfection of HUVECs with mimics of highly expressed in EVs miR-223-3p or miR-142-3p, stimulated production of IL-8, ST2 and endoglin. Cytokines released by HUVECs were also elevated in blood of patients with GPA. The most increased were IL-8, DKK-1, ST2, angiopoietin-2 and IL-33. In-vitro stimulation of HUVECs by neutrophil-derived EVs recapitulates contribution of endothelium in autoimmune vasculitis. Proinflammatory phenotype of released cytokines corresponds with the regulatory network of miRNAs/mRNAs comprising both EVs miRNA and endothelial cell transcripts.

Targeting the OXE receptor as a potential novel therapy for asthma

5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is an arachidonic acid metabolite formed by oxidation of the 5-lipoxygenase (5-LO) product 5S-hydroxy-6,8,11,14-eicosatetraenoic acid (5S-HETE) by the NADP+-dependent enzyme 5-hydroxyeicosanoid dehydrogenase. It is the only 5-LO product with appreciable chemoattractant activity for human eosinophils. Its actions are mediated by the selective OXE receptor, which is highly expressed on eosinophils, basophils, neutrophils and monocytes. Orthologs of the OXER1 gene, which encodes this receptor, are found in many species except for rodents. Intradermal injection of 5-oxo-ETE into humans and monkeys elicits eosinophil infiltration into the skin, raising the possibility that it may play a pathophysiological role in eosinophilic diseases. To investigate this and possibly identify a novel therapy we sought to prepare synthetic antagonists that could selectively block the OXE receptor. We synthesized a series of indole-based compounds bearing substituents that mimic the regions of 5-oxo-ETE that are required for biological activity, which we modified to reduce metabolism. The most potent of these OXE receptor antagonists is S-Y048, which is a potent inhibitor of 5-oxo-ETE-induced calcium mobilization (IC50, 20 pM) and has a long half-life following oral administration. S-Y048 inhibited allergen-induced eosinophil infiltration into the skin of rhesus monkeys that had been experimentally sensitized to house dust mite and inhibited pulmonary inflammation resulting from challenge with aerosolized allergen. These data provide the first evidence for a pathophysiological role for 5-oxo-ETE in mammals and suggest that potent and selective OXE receptor antagonists such as S-Y048 may be useful therapeutic agents in asthma and other eosinophilic diseases.