Lysophosphatidic Acid Receptor 3 Suppress Neutrophil Extracellular Traps Production and Thrombosis During Sepsis

Neutrophil extracellular traps: potential thrombotic markers and therapeutic targets in colorectal cancer

Neutrophil extracellular traps (NETs) are promising promoters in venous thromboembolism (VTE). In the present study, we have investigated the potential thrombogenic role of NETs in colorectal cancer (CRC). A total of 583 patients with gastrointestinal malignancies who were diagnosed with or without VTE by extremities arteriovenous ultrasound and computed tomography were enrolled. The incidence of VTE in CRC was as high as 17.53%. In serological ELISA experiments, Cit-H3, myeloperoxidase, and cfDNA were significantly overexpressed in CRC patients with VTE compared with CRC patients without VTE and healthy individuals. Neutrophils from CRC patients with VTE produced appreciable amounts of NETs after stimulation with phorbol-12-myristate-13-acetate, which were lacking in CRC patients without VTE and healthy individuals. CfDNA was positively correlated with plasmin-α2-antiplasmin complex and tissue plasmin activator inhibitor-1 complex, and Cit-H3 was positively correlated with plasmin-α2-antiplasmin complex, suggesting that NETs are associated with increased fibrinolytic activity. We screened some NETs-related genes by analyzing several high-throughput sequencing datasets of VTE and NETs. FCGR1A was identified as the optimal target gene by pan-cancer expression analysis and survival analysis. FCGR1A was significantly overexpressed in the peripheral blood of CRC patients without VTE compared with healthy individuals and showed a positive correlation with cfDNA. Neutrophil-derived NETs were significantly reduced by FCGR1A inhibitor exposure. These findings indicate that NETs are actively involved in VTE in CRC. NETs are promising thrombotic marker and therapeutic target in CRC to prevent the thrombotic consequences of cancer.

Interferon lambda signaling in neutrophils enhances the pathogenesis of Bordetella pertussis infection

Interferon lambda plays diverse roles in bacterial infections. Previously, we showed that interferon lambda is induced in the lungs of Bordetella pertussis-infected adult mice and exacerbates inflammation. Here, we report that mice lacking the interferon lambda receptor 1 specifically on neutrophils (MRP8creIFNLR1fl/fl mice) exhibit reduced lung bacterial load and inflammation compared to wild-type mice during B. pertussis infection. In B. pertussis-infected wild-type mice, lung type I and III IFN responses were higher than in MRP8creIFNLR1fl/fl mice, correlating with increased lung inflammatory pathology. There was an increased proportion of interferon gamma-producing neutrophils in the lungs of MRP8creIFNLR1fl/fl mice compared to wild-type mice. IFNLR1-/- neutrophils incubated with B. pertussis exhibited higher killing compared to wild-type neutrophils. Treatment of wild-type neutrophils with interferon lambda further decreased their bacterial killing capacity and treatment of wild-type mice with interferon lambda increased lung bacterial loads. Contributing to the differential killing, we found that IFNLR1-/- neutrophils exhibit higher levels of reactive oxygen species, myeloperoxidase, matrix metalloproteinase-9 activity, neutrophil extracellular traps, and interferon gamma secretion than wild-type neutrophils, and inhibiting NADPH oxidase inhibited bacterial killing in IFNLR1-/- neutrophils. B. pertussis-induced interferon lambda secretion and IFNLR1 gene expression in mouse and human neutrophils and this was dependent on the bacterial virulence protein pertussis toxin. Pertussis toxin enhanced bacterial loads in wild type but not in MRP8creIFNLR1fl/fl or IFNLR1-/- mice. Thus, pertussis toxin disrupts neutrophil function by enhancing type III IFN signaling, which prevents neutrophils from effectively clearing B. pertussis during infection, leading to higher bacterial loads and exacerbation of lung inflammation.

Deleting autotaxin in LysM+ myeloid cells impairs innate tumor immunity in models of metastatic melanoma

Autotaxin (ATX) is a lysophospholipase D that generates lysophosphatidic acid (LPA) and regulates cancer metastasis, therapeutic resistance, and tumor immunity. We found that myeloid cells in human melanoma biopsies abundantly express ATX and investigated its role in modulating innate tumor immunity using two models of melanoma metastasis-spontaneous and experimental. Targeted knockout of ATX in LysM+ myeloid cells in mice (LysM-KO) reduced both spontaneous and experimental B16-F10 melanoma metastases by ≥ 50%. Immunoprofiling revealed differences in M2-like alveolar macrophages, neutrophils and regulatory T cells in the metastatic lungs of LysM-WT versus LysM-KO that are model-dependent. These differences extend systemically, with LysM-KO mice bearing experimental metastasis having fewer neutrophils in the spleen than LysM-WT mice. Our results show that (1) LysM+ myeloid cells are an important source of ATX/LPA that promote melanoma metastasis by altering innate tumor immunity, and (2) intratumor and systemic immune profiles vary dynamically during disease progression and are model-dependent.

Lysophosphatidic acid, a simple phospholipid with myriad functions

Lysophosphatidic acid (LPA) is a simple phospholipid consisting of a phosphate group, glycerol moiety, and only one hydrocarbon chain. Despite its simple chemical structure, LPA plays an important role as an essential bioactive signaling molecule via its specific six G protein-coupled receptors, LPA_1-6. Recent studies, especially those using genetic tools, have revealed diverse physiological and pathological roles of LPA and LPA receptors in almost every organ system. Furthermore, many studies are illuminating detailed mechanisms to orchestrate multiple LPA receptor signaling pathways and to facilitate their coordinated function. Importantly, these extensive "bench" works are now translated into the "bedside" as exemplified by approaches targeting LPA₁ signaling to combat fibrotic diseases. In this review, we discuss the physiological and pathological roles of LPA signaling and their implications for clinical application by focusing on findings revealed by in vivo studies utilizing genetic tools targeting LPA receptors.

Modulations of urinary lipid mediators in acute bladder cystitis

Bioactive lipids, such as lysophospholipids, ceramides, and eicosanoids and related mediators, have been demonstrated to be involved in inflammation. We aimed to investigate the possible orchestral modulations of these bioactive lipids in human inflammation. We simultaneously measured the urinary levels of lysophospholipids, ceramides, and eicosanoids and related mediators by a liquid chromatography-mass spectrometry method in patients with cystitis and control subjects. The urinary levels of lysophosphatidylcholine, lysophosphatidylethanolamine, sphingosine 1-phosphate, ceramides, prostaglandin (PG)E₂ and its metabolites represented by tetranor-PGEM, several oxylipins, DHA, and lysoPAF were higher in patients with cystitis. Urinary levels of some species of glycerolysophospholipids were highly positively correlated with those of other species of the same glycerolysophospholipids. Cluster analyses revealed that lysophosphatidylcholine was close to a PGE₂ metabolite, lysophosphatidylethanolamine was close to DHA, and sphingosine 1-phosphate and ceramides were close to lysoPAF. The orchestral dynamism of the lipid mediators was observed in the urine of cystitis, suggesting the necessity for simultaneous investigation of lipid mediators for translational research.

Dynamic modulations of sphingolipids and glycerophospholipids in COVID-19

BACKGROUND

A heterogeneous clinical phenotype is a characteristic of coronavirus disease 2019 (COVID-19). Therefore, investigating biomarkers associated with disease severity is important for understanding the mechanisms responsible for this heterogeneity and for developing novel agents to prevent critical conditions. This study aimed to elucidate the modulations of sphingolipids and glycerophospholipids, which have been shown to possess potent biological properties.

METHODS

We measured the serum sphingolipid and glycerophospholipid levels in a total of 887 samples from 215 COVID-19 subjects, plus 115 control subjects without infectious diseases and 109 subjects with infectious diseases other than COVID-19.

RESULTS

We observed the dynamic modulations of sphingolipids and glycerophospholipids in the serum of COVID-19 subjects, depending on the time course and severity. The elevation of C16:0 ceramide and lysophosphatidylinositol and decreases in C18:1 ceramide, dihydrosphingosine, lysophosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol were specific to COVID-19. Regarding the association with maximum severity, phosphatidylinositol and phosphatidylcholine species with long unsaturated acyl chains were negatively associated, while lysophosphatidylethanolamine and phosphatidylethanolamine were positively associated with maximum severity during the early phase. Lysophosphatidylcholine and phosphatidylcholine had strong negative correlations with CRP, while phosphatidylethanolamine had strong positive ones. C16:0 ceramide, lysophosphatidylcholine, phosphatidylcholine and phosphatidylethanolamine species with long unsaturated acyl chains had negative correlations with D-dimer, while phosphatidylethanolamine species with short acyl chains and phosphatidylinositol had positive ones. Several species of phosphatidylcholine, phosphatidylethanolamine and sphingomyelin might serve as better biomarkers for predicting severe COVID-19 during the early phase than CRP and D-dimer. Compared with the lipid modulations seen in mice treated with lipopolysaccharide, tissue factor, or histone, the lipid modulations observed in severe COVID-19 were most akin to those in mice administered lipopolysaccharide.

CONCLUSION

A better understanding of the disturbances in sphingolipids and glycerophospholipids observed in this study will prompt further investigation to develop laboratory testing for predicting maximum severity and/or novel agents to suppress the aggravation of COVID-19.

Extracellular traps and the role in thrombosis

Thrombotic complications pose serious health risks worldwide. A significant change in our understanding of the pathophysiology of thrombosis has occurred since the discovery of extracellular traps (ETs) and their prothrombotic properties. As a result of immune cells decondensing chromatin into extracellular fibers, ETs promote thrombus formation by acting as a scaffold that activates platelets and coagulates them. The involvement of ETs in thrombosis has been reported in various thrombotic conditions including deep vein thrombosis (DVT), pulmonary emboli, acute myocardial infarction, aucte ischemic stroke, and abdominal aortic aneurysms. This review summarizes the existing evidence of ETs in human and animal model thrombi. The authors described studies showing the existence of ETs in venous or arterial thrombi. In addition, we studied potential novel therapeutic opportunities related to the resolution or prevention of thrombosis by targeting ETs.