Self-extinguishing relay waves enable homeostatic control of human neutrophil swarming.

Neutrophils collectively migrate to sites of injury and infection. How these swarms are coordinated to ensure the proper level of recruitment is unknown. Using an ex vivo model of infection, we show that human neutrophil swarming is organized by multiple pulsatile chemoattractant waves. These waves propagate through active relay in which stimulated neutrophils trigger their neighbors to release additional swarming cues. Unlike canonical active relays, we find these waves to be self-terminating, limiting the spatial range of cell recruitment. We identify an NADPH-oxidase-based negative feedback loop that is needed for this self-terminating behavior. We observe near-constant levels of neutrophil recruitment over a wide range of starting conditions, revealing surprising robustness in the swarming process. This homeostatic control is achieved by larger and more numerous swarming waves at lower cell densities. We link defective wave termination to a broken recruitment homeostat in the context of human chronic granulomatous disease.

Biological Evaluation of Lysionotin: a Novel Inhibitor of 5-Lipoxygenase for Anti-glioma.

OBJECTIVE: To explore the potential mechanism of lysionotin in treating glioma. METHODS: First, target prediction based on Bernoulli Naïve Bayes profiling and pathway enrichment was used to predict the biological activity of lysionotin. The binding between 5-lipoxygenase (5-LO) and lysionotin was detected by surface plasmon resonance (SPR) and molecular docking, and the inhibitory effects of lysionotin on 5-LO and proliferation of glioma were determined using enzyme inhibition assay in vitro and cell viability analysis, respectively. Furthermore, the pharmaceutical effect of lysionotin was explored by cell survival rate analysis and liquid chromatography with tandem mass spectrometry (LC-MS/MS). The protein expression, intracellular calcium ion concentration and cytoskeleton detection were revealed by Western blot, flow cytometry and fluorescence labeling, respectively. RESULTS: Target prediction and pathway enrichment revealed that lysionotin inhibited 5-LO, a key enzyme involved in the arachidonic acid metabolism pathway, to inhibit the proliferation of glioma. Molecular docking results demonstrated that 5-LO can be binding to lysionotin through hydrogen bonds, forming bonds with His600, Gln557, Asn554, and His372. SPR analysis further confirmed the interaction between 5-LO and lysionotin. Furthermore, enzyme inhibition assay in vitro and cell survival rate analysis revealed that 50% inhibition concentration of lysionotin and the median effective concentration of lysionotin were 90 and 16.58 µmol/L, respectively, and the results of LC-MS/MS showed that lysionotin inhibited the production of 5S-hydroperoxy-eicosatetraenoic acid (P<0.05), and moreover, the LC-MS/MS results indicated that lysionotin can enter glioma cells well (P<0.01) and inhibit their proliferation. Western blot analysis demonstrated that lysionotin can inhibit the expression of 5-LO (P<0.05) and downstream leukotriene B4 receptor (P<0.01). In addition, the results showed that lysionotin affected intracellular calcium ion concentration by inhibiting 5-LO to affect the cytoskeleton, as determined by flow cytometry and fluorescence labeling. CONCLUSION: Lysionotin binds to 5-LO could suppress glioma by inhibiting arachiodonic acid metabolism pathway.

ATP and Formyl Peptides Facilitate Chemoattractant Leukotriene-B4 Synthesis and Drive Calcium Fluxes, Which May Contribute to Neutrophil Swarming at Sites of Cell Damage and Pathogens Invasion.

Here, we demonstrate that human neutrophil interaction with the bacterium Salmonella typhimurium fuels leukotriene B4 synthesis induced by the chemoattractant fMLP. In this work, we found that extracellular ATP (eATP), the amount of which increases sharply during tissue damage, can effectively regulate fMLP-induced leukotriene B4 synthesis. The vector of influence strongly depends on the particular stage of sequential stimulation of neutrophils by bacteria and on the stage at which fMLP purinergic signaling occurs. Activation of 5-lipoxygenase (5-LOX), key enzyme of leukotriene biosynthesis, depends on an increase in the cytosolic concentration of Ca2+. We demonstrate that eATP treatment prior to fMLP, by markedly reducing the amplitude of the fMLP-induced Ca2+ transient jump, inhibits leukotriene synthesis. At the same time, when added with or shortly after fMLP, eATP effectively potentiates arachidonic acid metabolism, including by Ca2+ fluxes stimulation. Flufenamic acid, glibenclamide, and calmodulin antagonist R24571, all of which block calcium signaling in different ways, all suppressed 5-LOX product synthesis in our experimental model, indicating the dominance of calcium-mediated mechanisms in eATP regulatory potential. Investigation into the adhesive properties of neutrophils revealed the formation of cell clusters when adding fMLP to neutrophils exposed to the bacterium Salmonella typhimurium. eATP added simultaneously with fMLP supported neutrophil polarization and clustering. A cell-derived chemoattractant such as leukotriene B4 plays a crucial role in the recruitment of additional neutrophils to the foci of tissue damage or pathogen invasion, and eATP, through the dynamics of changes in [Ca2+]i, plays an important decisive role in fMLP-induced leukotrienes synthesis during neutrophil interactions with the bacterium Salmonella typhimurium.

Leukotriene B4: A potential mediator and biomarker for cardiac allograft vasculopathy.

BACKGROUND: Cardiac allograft vasculopathy (CAV) remains the leading cause of long-term graft failure and mortality after heart transplantation. Effective preventive and treatment options are not available to date, largely because underlying mechanisms remain poorly understood. We studied the potential role of leukotriene B4 (LTB4), an inflammatory lipid mediator, in the development of CAV. METHODS: We used an established preclinical rat CAV model to study the role of LTB4 in CAV. We performed syngeneic and allogeneic orthotopic aortic transplantation, after which neointimal proliferation was quantified. Animals were then treated with Bestatin, an inhibitor of LTB4 synthesis, or vehicle control for 30 days post-transplant, and evidence of graft CAV was determined by histology. We also measured serial LTB4 levels in a cohort of 28 human heart transplant recipients with CAV, 17 matched transplant controls without CAV, and 20 healthy nontransplant controls. RESULTS: We showed that infiltration of the arterial wall with macrophages leads to neointimal thickening and a rise in serum LTB4 levels in our rat model of CAV. Inhibition of LTB4 production with the drug Bestatin prevents development of neointimal hyperplasia, suggesting that Bestatin may be effective therapy for CAV prevention. In a parallel study of heart transplant recipients, we found nonsignificantly elevated plasma LTB4 levels in patients with CAV, compared to patients without CAV and healthy, nontransplant controls. CONCLUSIONS: This study provides key evidence supporting the role of the inflammatory cytokine LTB4 as an important mediator of CAV development and provides preliminary data suggesting the clinical benefit of Bestatin for CAV prevention.

Leukotriene B4-induced neutrophil extracellular traps impede the clearance of Pneumocystis.

Pneumocystis pneumonia (PCP) is a fungal pulmonary disease with high mortality in immunocompromised patients. Neutrophils are essential in defending against fungal infections; however, their role in PCP is controversial. Here we aim to investigate the effects of neutrophil extracellular traps (NETs) on Pneumocystis clearance and lung injury using a mouse model of PCP. Intriguingly, although neutrophils play a fundamental role in defending against fungal infections, NETs failed to eliminate Pneumocystis, but instead impaired the killing of Pneumocystis. Mechanically, Pneumocystis triggered Leukotriene B4 (LTB4)-dependent neutrophil swarming, leading to agglutinative NET formation. Blocking Leukotriene B4 with its receptor antagonist Etalocib significantly reduced the accumulation and NET release of neutrophils in vitro and in vivo, enhanced the killing ability of neutrophils against Pneumocystis, and alleviated lung injury in PCP mice. This study identifies the deleterious role of agglutinative NETs in Pneumocystis infection and reveals a new way to prevent NET formation, which provides new insights into the pathogenesis of PCP.

Leukotriene B4 levels in CHD-associated paediatric pulmonary hypertension.

BACKGROUND: The aim of this study is to evaluate the role of leukotriene B4, an inflammatory mediator, in the development of pulmonary hypertension in paediatric patients with CHD with left-right shunt. METHODS: The study included forty patients with CHD with left-right shunts. Based on haemodynamic data obtained from cardiac diagnostic catheterisation, 25 patients who met the criteria for pulmonary arterial hypertension were included in the patient group. The control group comprised 15 patients who did not meet the criteria. The standard cardiac haemodynamic study was conducted. Leukotriene B4 levels were assessed in blood samples taken from both pulmonary arteries and peripheral veins. RESULTS: The median age of patients with pulmonary arterial hypertension was 10 months (range: 3-168), while the median age of the control group was 50 months (range: 3-194). In the pulmonary hypertension group, the median pulmonary artery systolic/diastolic/mean pressures were 38/18/24 mmHg, compared to 26/10/18 mmHg in the control group. Leukotriene B4 levels in pulmonary artery blood samples were significantly higher in the pulmonary arterial hypertension group compared to the controls (p < 0.05). Peripheral leukotriene B4 levels were also elevated in the pulmonary arterial hypertension group in comparison to the control group, though the difference was not statistically significant. CONCLUSION: The discovery of elevated leukotriene B4 levels in pulmonary artery samples from paediatric patients with pulmonary arterial hypertension secondary to CHD with left-to-right shunt suggests that local inflammation may have a pathological role in the development of pulmonary arterial hypertension.

Prostaglandin E2/Leukotriene B4 balance and viral load in distinct clinical stages of COVID-19: A cross-sectional study.

BACKGROUND: Prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) are eicosanoids involved in modulation of the antiviral immune response. Recent studies have identified increased levels of several eicosanoids in the plasma and bronchoalveolar lavage of patients with coronavirus disease (COVID-19). This study investigated correlations between plasma levels of PGE2 and LTB4 and clinical severity of COVID-19. METHODS: This cross-sectional study involved non-infected (n = 10) individuals and COVID-19 patients classified as cured (n = 13), oligosymptomatic (n = 29), severe (n = 15) or deceased (n = 11). Levels of D-dimer a, known COVID-19 severity marker, PGE2 and LTB4 were measured by ELISAs and data were analysed with respect to viral load. RESULTS: PGE2 plasma levels were decreased in COVID-19 patients compared to the non-infected group. Changes in PGE2 and LTB4 levels did not correlate with any particular clinical presentations of COVID-19. However, LTB4 was related to decreased SARS-CoV-2 burden in patients, suggesting that only LTB4 is associated with control of viral load. CONCLUSIONS: Our data indicate that PGE2/LTB4 plasma levels are not associated with COVID-19 clinical severity. Hospitalized patients with COVID-19 are treated with corticosteroids, which may influence the observed eicosanoid imbalance. Additional analyses are required to fully understand the participation of PGE2 receptors in the pathophysiology of COVID-19.

Redox processes are major regulators of leukotriene synthesis in neutrophils exposed to bacteria Salmonella typhimurium; the way to manipulate neutrophil swarming.

Neutrophils play a primary role in protecting our body from pathogens. When confronted with invading bacteria, neutrophils begin to produce leukotriene B4, a potent chemoattractant that, in cooperation with the primary bacterial chemoattractant fMLP, stimulates the formation of swarms of neutrophils surrounding pathogens. Here we describe a complex redox regulation that either stimulates or inhibits fMLP-induced leukotriene synthesis in an experimental model of neutrophils interacting with Salmonella typhimurium. The scavenging of mitochondrial reactive oxygen species by mitochondria-targeted antioxidants MitoQ and SkQ1, as well as inhibition of their production by mitochondrial inhibitors, inhibit the synthesis of leukotrienes regardless of the cessation of oxidative phosphorylation. On the contrary, antioxidants N-acetylcysteine and sodium hydrosulfide promoting reductive shift in the reversible thiol-disulfide system stimulate the synthesis of leukotrienes. Diamide that oxidizes glutathione at high concentrations inhibits leukotriene synthesis, and the glutathione precursor S-adenosyl-L-methionine prevents this inhibition. Diamide-dependent inhibition is also prevented by diphenyleneiodonium, presumably through inhibition of NADPH oxidase and NADPH accumulation. Thus, during bacterial infection, maintaining the reduced state of glutathione in neutrophils plays a decisive role in the synthesis of leukotriene B4. Suppression of excess leukotriene synthesis is an effective strategy for treating various inflammatory pathologies. Our data suggest that the use of mitochondria-targeted antioxidants may be promising for this purpose, whereas known thiol-based antioxidants, such as N-acetylcysteine, may dangerously stimulate leukotriene synthesis by neutrophils during severe pathogenic infection.

Two distinct forms of human BLT2: long-form and short-form BLT2.

BLT2 is a low-affinity leukotriene B4 receptor that plays an essential role in the pathogenesis of various inflammatory diseases, including asthma and cancer. BLT2 is minimally expressed in a normal internal environment but is overexpressed in a stress-induced inflammatory environment. Recent research indicated that human BLT2 has two distinct forms. Although their functions are likely to be different, very few studies investigated these differences. Therefore, this paper will discuss about the two distinct forms of human BLT2; the short-form of BLT2 and the long-form of BLT2.

Caffeic acid modulates activation of neutrophils and attenuates sepsis-induced organ injury by inhibiting 5-LOX/LTB4 pathway.

BACKGROUND: Sepsis is a critical systemic inflammatory syndrome which usually leads to multiple organ dysfunction. Caffeic acid (CA), a phenolic compound derived from various plants, has been proved to be essential in neuroprotection, but its role in septic organ damage is unclear. This research aimed to investigate whether CA protects against organ injury in a mouse model of cecal ligation and puncture (CLP). METHODS: CA (30 mg/kg) or vehicle was administered by intraperitoneal injection immediately after CLP. The samples of blood, lungs, and livers were collected 24 h later. Organ injury was assessed by histopathological examination (HE staining), neutrophil infiltration (myeloperoxidase fluorescence), oxidative stress levels (MDA, SOD, HO-1), and inflammatory cytokines (TNF-α, IL-1ß, and IL-6) release in lung and liver tissues. Neutrophil extracellular trap (NET) formation was analyzed by immunofluorescence. In vitro experiments were performed to investigate the potential mechanisms of CA using small interfering RNA (siRNA) techniques in neutrophils, and the effect of CA on neutrophil apoptosis was analyzed by flow cytometry. RESULTS: Results showed that CA treatment improved the 7-day survival rate and attenuated the histopathological injury in the lung and liver of CLP mice. CA significantly reduced neutrophil infiltration in the lungs and livers of CLP mice. TNF-α, IL-1ß, IL-6 and LTB4 were reduced in serum, lung, and liver of CA-treated CLP mice, and phosphorylation of MAPK (p38, ERK, JNK) and p65 NF-κB was inhibited in lungs and livers. CA treatment further increased HO-1 levels and enhanced superoxide dismutase (SOD) activity, but reduced malondialdehyde (MDA) levels and NET formation. Similarly, in vitro experiments showed that CA treatment and 5-LOX siRNA interference inhibited inflammatory activation and NET release in neutrophils, suppressed MAPK and NF-κB phosphorylation in LPS-treated neutrophils, and decreased LTB4 and cfDNA levels. Flow cytometric analysis revealed that CA treatment reversed LPS-mediated delayed apoptosis in human neutrophils, and Western blot also indicated that CA treatment inhibited Bcl-2 expression but increased Bax expression. CA treatment did not induce further changes in neutrophil apoptosis, inflammatory activation, and NET release when 5-LOX was knocked down by siRNA interference. CONCLUSIONS: CA has a protective effect on lung and liver injury in a murine model of sepsis, which may be related to inhibition of the 5-LOX/LTB4 pathway.

Discovery of a novel BLT2 antagonist for the treatment of inflammatory airway diseases.

Leukotriene B4 (LTB4) is a potent chemoattractant that can recruit and activate immune cells such as neutrophils, eosinophils, and monocytes to sites of inflammation. Excessive production of LTB4 has been linked to acute and chronic inflammatory diseases, including asthma, rheumatoid arthritis, and psoriasis. Inhibiting the binding of LTB4 to its receptors, BLT1 and BLT2, is a potential strategy for treating these conditions. While several BLT1 antagonists have been developed for clinical trials, most have failed due to efficacy and safety issues. Therefore, discovering selective BLT2 antagonists could improve our understanding of the distinct functions of BLT1 and BLT2 receptors and their pharmacological implications. In this study, we aimed to discover novel BLT2 antagonists by synthesizing a series of biphenyl analogues based on a BLT2 selective agonist, CAY10583. Among the synthesized compounds, 15b was found to selectively inhibit the chemotaxis of CHO-BLT2 cells with an IC50 value of 224 nM without inhibiting the chemotaxis of CHO-BLT1 cells. 15b also inhibited the binding of LTB4 and BLT2 with a Ki value of 132 nM. Furthermore, 15b had good metabolic stability in liver microsomes and moderate bioavailability (F = 34%) in in vivo PK studies. 15b also showed in vivo efficacy in a mouse model of asthma, reducing airway hyperresponsiveness by 59% and decreasing Th2 cytokines by up to 46%. Our study provides a promising lead for the development of selective BLT2 antagonists as potential therapeutics for inflammatory airway diseases such as asthma and chronic obstructive pulmonary disease.

Stepwise phosphorylation of BLT1 defines complex assemblies with ß-arrestin serving distinct functions.

G protein-coupled receptors (GPCRs) utilize complex cellular systems to respond to diverse ligand concentrations. By taking BLT1, a GPCR for leukotriene B4 (LTB4 ), as a model, our previous work elucidated that this system functions through the modulation of phosphorylation status on two specific residues: Thr308 and Ser310 . Ser310 phosphorylation occurs at a lower LTB4 concentration than Thr308 , leading to a shift in ligand affinity from a high-to-low state. However, the implications of BLT1 phosphorylation in signal transduction processes or the underlying mechanisms have remained unclear. Here, we identify the sequential BLT1-engaged conformations of ß-arrestin and subsequent alterations in signal transduction. Stimulation of the high-affinity BLT1 with LTB4 induces phosphorylation at Ser310 via the ERK1/2-GRK pathway, resulting in a ß-arrestin-bound low-affinity state. This configuration, referred to as the "low-LTB4 -induced complex," necessitates the finger loop region and the phosphoinositide-binding motif of ß-arrestins to interact with BLT1 and deactivates the ERK1/2 signaling. Under high LTB4 concentrations, the low-affinity BLT1 again binds to the ligand and triggers the generation of the low-LTB4 -induced complex into a different form termed "high-LTB4 -induced complex." This change is propelled by The308 -phosphorylation-dependent basal phosphorylation by PKCs. Within the high-LTB4 -induced complex, ß-arrestin adapts a unique configuration that involves additional N domain interaction to the low-affinity BLT1 and stimulates the PI3K/AKT pathway. We propose that the stepwise phosphorylation of BLT1 defines the formation of complex assemblies, wherein ß-arrestins perform distinct functions.

Imbalanced serum levels of resolvin E1 (RvE1) and leukotriene B4 (LTB4) may contribute to the pathogenesis of atherosclerosis.

Persistent and chronic unresolved inflammation exerts a critical role in developing atherosclerosis; however, mechanisms that prevent the resolution of inflammation in atherosclerosis are poorly delineated. This study aims to evaluate the serum levels of inflammatory high-sensitivity C-reactive protein (hsCRP), pro-inflammatory leukotriene B4 (LTB4), besides anti-inflammatory compounds, including eicosapentaenoic acid (EPA) and its derivative resolvin E1 (RvE1) in patients with atherosclerosis. Thirty-four atherosclerosis patients and thirty-two age- and sex-matched healthy individuals were included in this study. The serum levels of hsCRP, LTB4, EPA, and RvE1 were measured using the enzyme-linked immunosorbent assay (ELISA) technique. Our results showed that the hsCRP serum levels in the three-vessel disease (3VD) subgroup of patients are significantly lower than those in the mild and single-vessel disease (SVD) subgroups (P < 0.05). Besides, the serum levels of LTB4 were meaningfully greater in patients with atherosclerosis compared to healthy controls (P < 0.05). Also, the serum EPA and RvE1 levels were significantly higher in patients than in controls (P < 0.01 and P < 0.05, respectively). However, the ratio of RvE1 to LTB4 (RvE1:LTB4) in patients was significantly reduced to that in controls (P < 0.0001). These findings illustrate that imbalanced pro-resolving RvE1 and pro-inflammatory LTB4 might contribute to failing vascular inflammation resolution and subsequent progression toward chronic inflammation in atherosclerosis.

Therapeutic target of leukotriene B4 receptors, BLT1 and BLT2: Insights from basic research.

Leukotriene B4 (LTB4) is a lipid mediator rapidly generated from arachidonic acid in response to various stimuli. This lipid mediator exerts its biological activities by binding to cognate receptors. Two LTB4 receptors have been cloned; BLT1 and BLT2 as a high- and a low-affinity receptors, respectively. In numerous analyses, physiological and pathophysiological importance of LTB4 and cognate receptors in various diseases has been clarified. For example, disruption of the BLT1 gene or treatment with blockers for this receptor reduced various diseases such as rheumatoid arthritis and bronchial asthma in mice, in contrast BLT2 deficiency facilitated several diseases in the small intestine and the skin. These data support the idea that BLT1 blockers and BLT2 agonists could be useful for the cure of these diseases. Thus, various drugs targeting each receptor are being developed by many pharmaceutical companies. In this review, we focus on our current knowledge of the biosynthesis and physiological roles of LTB4 through cognate receptors. We further describe the effects of these receptor deficiencies on several pathophysiological conditions, including the potential of LTB4 receptors as therapeutic targets for the cure of the diseases. Moreover, current information on the structure and post-translational modification of BLT1 and BLT2 is discussed.

CDCT-induced nephrotoxicity in rat by apoptosis via metabolic disturbance.

Compound diclofenac sodium chlorphenamine maleate tablets (CDCT) are widely used for the cold in Asia. However, CDCT can cause hematuria symptoms in clinical, and the underlying mechanism is unknown. This study aims to investigate the CDCT-induced changes of morphology in kidney and metabolites and further explore the possible mechanisms of CDCT-induced nephrotoxicity. Sprague-Dawley rats were exposed to the CDCT at a clinical equivalent dose for 6 days. CDCT exposure can induce kidney injury and death. Pathological changes, including creatinine, urea nitrogen, and histopathology, were observed in rats. Furthermore, metabolomic-driven energy and glycerophospholipid metabolism pathway disorders, accompanied by remarkably changed key metabolites, such as succinate, leukotriene B4 (LTB4 ), and cardiolipin (CL), are observed in the CDCT-induced nephrotoxicity. Functionally, succinate accumulation leads to mitochondrial damage, as evidence by the imbalance of complex I and complex II and an increase in mitochondrial reactive oxygen species (mito SOX). Meanwhile, LTB4 activated the NF-κB signaling, as shown by increased protein of p65, phosphor-p65, and decreased protein of IκBα and phosphor-IκBα. Eventually, the apoptosis pathway was triggered in response to reduced CL, inflammation, and mito SOX, as demonstrated by the expression of cyt c, Bax, Bcl-2, caspase-3, and caspase-9. This study indicated that CDCT-induced metabolic disorders triggered nephrotoxicity and provided a comprehensive information to elucidate the mechanism of CDCT induced nephrotoxicity.

[Regulatory effect of moxibustion on LTB4/MMP-9 in serum of patients with rheumatoid arthritis].

OBJECTIVE: To observe the effects of moxibustion on the contents of leukotriene B4 (LTB4), interleukin-17 (IL-17), tumor necrosis factor-α (TNF-α) and matrix metalloproteinase -9 (MMP-9) in serum, and explore the protection mechanisms of moxibustion in the patients with rheumatoid arthritis (RA). METHODS: A total of 64 patients with RA were randomly divided into treatment group (n=31) and control group (n=33). The patients in the control group were treated with conventional medication for consecutive 5 weeks. Based on the treatment in the control group, the patients in the treatment group were treated with moxibustion at bilateral Shenshu (BL23), Zusanli (ST36) and Ashi points, 3 times a week, for consecutive 5 weeks. Separately, the visual analogue scale (VAS) score, morning stiffness score, the number of tender joints, the number of swollen joints, the score of the disease activity score of 28 joints (DAS28) were observed; the contents of rheumatoid factor (RF), erythrocyte sedimentation rate (ESR) and C-reative protein (CRP) in serum were determined by biochemical method; and the contents of LTB4, IL-17, TNF-α and MMP-9 in serum were detected by using ELISA before and after treatment in the patients of both groups. RESULTS: After treatment, VAS score, morning stiffness score, the number of tender joints, the number of swollen joints, DAS28 score, the contents of serum RF in both groups, and contents of serum CRP, ESR, LTB4, IL-17, TNF-α and MMP-9 in the treatment group were significantly reduced when compared with those before treatment (P<0.01, P<0.05). After treatment, VAS score, morning stiffness score, the number of tender joints, the number of swollen joints, DAS28 score, and the levels of LTB4, IL-17 and MMP-9 in serum were obviously lower in the treatment group when compared with the control group (P<0.01, P<0.05). In the treatment group, the changes before and after treatment in the levels of LTB4, IL-17 and TNF-α were positively correlated with that of MMP-9 (P<0.05, r>0). CONCLUSION: Moxibustion at BL23 and ST36 combined with conventional medication significantly relieves joint pain and reduce disease activity in RA patients, which may be related to the modulation of LTB4, IL-17 and MMP-9 by moxibustion.

Roles of the peroxisome proliferator-activated receptors (PPARs) in the pathogenesis of nonalcoholic fatty liver disease (NAFLD).

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of disease phenotypes which start with simple steatosis and lipid accumulation in the hepatocytes - a typical histological lesions characteristic. It may progress to non-alcoholic steatohepatitis (NASH) that is characterized by hepatic inflammation and/or fibrosis and subsequent onset of NAFLD-related cirrhosis and hepatocellular carcinoma (HCC). Due to the central role of the liver in metabolism, NAFLD is regarded as a result of and contribution to the metabolic abnormalities seen in the metabolic syndrome. Peroxisome proliferator-activated receptors (PPARs) has three subtypes, which govern the expression of genes responsible for energy metabolism, cellular development, inflammation, and differentiation. The agonists of PPARα, such as fenofibrate and clofibrate, have been used as lipid-lowering drugs in clinical practice. Thiazolidinediones (TZDs) - ligands of PPARγ, such as rosiglitazone and pioglitazone, are also used in the treatment of type 2 diabetes (T2D) with insulin resistance (IR). Increasing evidence suggests that PPARß/δ agonists have potential therapeutic effects in improving insulin sensitivity and lipid metabolism disorders. In addition, PPARs ligands have been considered as potential therapeutic drugs for hypertension, atherosclerosis (AS) or diabetic nephropathy. Their crucial biological roles dictate the significance of PPARs-targeting in medical research and drug discovery. Here, it reviews the biological activities, ligand selectivity and biological functions of the PPARs family, and discusses the relationship between PPARs and the pathogenesis of NAFLD and metabolic syndrome. This will open new possibilities for PPARs application in medicine, and provide a new idea for the treatment of fatty liver and related diseases.

The Role of Leukotriene B4 in Cow Metritis.

Introduction: Metritis is a common postpartum disease in dairy cows. As a mast cell (MC) mediator, leukotriene B4 (LTB4) is the strongest phagocyte chemokine. It is important in inflammation for the recruitment of immune cells to resist infection. This study investigated the effect of LTB4 in metritis. Material and Methods: Twenty Holstein cows 3 to 6 years old and at 6 to 10 days postpartum were selected, ten of which with postpartum metritis were the experimental group, and the other ten of which as healthy cows were the control group. The levels of LTB4, substance P (SP) and vasoactive intestinal peptide (VIP) were measured by ELISA, the expression of LTB4 receptor 2 (BLT2), matrix metalloproteinase (MMP)-2 and MMP-9 mRNA was measured by qPCR, and collagens I and IV were detected by immunohistochemical staining. Results: Concentrations of SP and LTB4 were significantly higher, but those of VIP were significantly lower in the experimental group than those in the control group. The expression of BLT2, MMP-2 and MMP-9 mRNA was significantly higher in the experimental group than that in the control group. The expression of collagen Ⅰ and collagen Ⅳ was significantly lower in the experimental group than that in the control group. Conclusion: In metritis, SP promotes the activation of MC and the synthesis and release of LTB4. Leukotriene B4 chemotactic immune cells promote the high expression of collagenase, which accelerated the hydrolysis of collagen, while the inhibitory effect of VIP on MC was weakened. This may further aggravate the damage to uterine tissue.

New and promising type of leukotriene B4 (LTB4) antagonists based on the 1,4-benzodioxine structure.

New leukotriene B4 (LTB4) antagonists have been synthesized that can be considered as potential anti-inflammatory drugs. Structures containing the dioxygenated nucleus of 1,4-benzodioxine constitute a potential group of leukotriene B4 (LTB4) antagonists. The objective of this study was to access efficient and selective LTB4 antagonists as a way to elucidate the role of LTB4 in inflammatory processes and therefore allow the development of new types of structures based on 1,4-benzodioxine. Forty-one new 1,4-benzodioxine molecules substituted at different positions of the heterocyclic nucleus were synthesized to determine the minimum structural requirements by studying structure-activity relationships. Eighteen of them were tested in vitro and in vivo for their anti-inflammatory activity related to the antagonist character of LTB4. Pharmacological tests have shown satisfactory in vitro activity for compounds 24b, 24c and 24e with IC50's of 288, 439, 477 nM respectively. The results of the in vivo tests, carried out with the compound that presented greater activity in the in vitro tests 24b, have shown significant anti-inflammatory properties.

Endothelial Protein kinase D1 is a major regulator of post-traumatic hyperinflammation.

Trauma is a major cause of death worldwide. The post-traumatic immune response culminates in the release of pro-inflammatory mediators, translating in the infiltration of neutrophils (PMNs) at injury sites. The extent of this inflammation is determined by multiple factors, such as PMN adhesion to the endothelium, transendothelial migration, endothelial barrier integrity as well as PMN swarming, mass infiltration and activation. This process is initiated by secondary lipid mediators, such as leukotriene B4 (LTB4). We here provide evidence that Protein kinase D1 (PRKD1) in endothelial cells is implicated in all these processes. Endothelial PRKD1 is activated by pro-inflammatory stimuli and amplifies PMN-mediated inflammation by upregulation of cytokine and chemokines as well as adhesion molecules, such as ICAM-1, VCAM-1 and E-selectin. This induces enhanced PMN adhesion and trans-migration. PRKD1 activation also destabilizes endothelial VE-cadherin adhesion complexes and thus the endothelial barrier, fostering PMN infiltration. We even describe a yet unrecognized PRKD1-dependant mechanism to induce biosynthesis of the PMN-swarming mediator LTB4 directed via intercellular communication through small extracellular vesicles (sEVs) and enhanced CXCL8 secretion from activated endothelial cells. These endothelial sEVs transfer the LTB4 biosynthesis enzyme LTA4 hydrolase (LTA4H) to prime PMNs, while initiating biosynthesis also requires additional signals, like CXCL8. We further demonstrate the respective LTA4H-positive sEVs in the serum of polytrauma patients, peaking 12 h post injury. Therefore, PRKD1 is a key regulator in the coordinated communication of the endothelium with PMNs and a vital signaling node during post-traumatic inflammation.