Expression and significance of procalcitonin, leukotriene B4, serum amyloid A, and C-reactive protein in children with different types of pneumonia: An observational study.

This study aimed to investigate the expression and significance of serum procalcitonin (PCT), leukotriene B4 (LTB4), Serum amyloid A (SAA), and C-reactive protein (CRP) in children with different types of pneumonia caused by different pathogenic infections. One hundred and one children with pneumonia admitted to The Fifth People Hospital of Zhuhai from July 2019 to June 2020 were enrolled and divided into 38 cases in the bacterial group, 30 cases in the mycoplasma group, and 33 cases in the virus group according to the different types of pathogens. The patients were divided into 42 cases in the noncritical group, 33 cases in the critical group, and 26 cases in the very critical group according to the pediatric clinical illness score (PCIS), and 30 healthy children were selected as the control group during the same period. Comparison of serum PCT, SAA: bacterial group > mycoplasma group > viral group > control group with significant differences (P < .05). Receiver operator characteristic (ROC) analysis showed that the area under the curves (AUCs) of serum PCT, LTB4, SAA, and CRP for the diagnosis of bacterial pneumonia were 1.000, 0.531, 0.969, and 0.833, respectively, and the AUCs for the diagnosis of mycoplasma pneumonia were 0.653, 0.609, 0.547, and 0.652, respectively, and the AUCs for the diagnosis of viral pneumonia were 0.888, 0.570, 0.955, and 1.000, respectively. Comparison of serum PCT, LTB4, SAA: very critical group > critical group > noncritical group > control group, with significant differences (P < .05). Serum PCT, LTB4, and SAA were negatively correlated with PCIS score by Pearson analysis (P < .05). Serum PCT and SAA showed diagnostic value for bacterial pneumonia, and serum SAA and CRP showed diagnostic value for viral pneumonia; serum PCT, LTB4, and SAA correlate with severity of disease and show higher expression with worsening of the condition.

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.

Longitudinal assessment of leukotriene B4, lipoxin A4, and resolvin D1 plasma levels in pregnant women with risk factors for preeclampsia.

OBJECTIVES: We carried out a longitudinal study to compare leukotriene B4 (LTB4), lipoxin A4 (LXA4), and resolvin D1 (RvD1) levels in pregnant women with risk factors for PE - who did (N = 11) or did not develop (N = 17) this clinical condition. DESIGN & METHODS: For both groups, plasma levels of the lipid mediators were measured using immunoassays at 12-19, 20-29, and 30-34 weeks of gestation. RESULTS: LTB4 tended to be upregulated throughout gestation in women who developed PE. Moreover, this increase was significant at 30-34 weeks. Although LXA4 levels also tended to be higher in the PE group, this difference was not significant for the evaluated gestational periods. Pregnant women with PE had lower RvD1 levels and a low RvD1/LTB4 ratio at 30-34 weeks, compared to those in the normotensive pregnant women. Contrarily, RvD1 levels increased at weeks 12-19 in pregnant women who developed PE. Particularly, LXA4 and RvD1 levels were higher at 30-34 weeks than those at 20-29 weeks considering both groups of women. We observed an interaction between the gestational outcome and the gestational period in case of RvD1. CONCLUSIONS: The imbalance among LTB4, LXA4, and RvD1 levels in these preeclamptic women is consistent with the excessive inflammation that underlies the pathogenesis of PE. Although our data highlight the potential for the use of these lipid mediators as clinical markers for PE development, future longitudinal studies must be carried out to confirm these findings.

Effects of Sodium Selenite Injection on Serum Metabolic Profiles in Women Diagnosed with Breast Cancer-Related Lymphedema-Secondary Analysis of a Randomized Placebo-Controlled Trial Using Global Metabolomics.

In our previous study, intravenous (IV) injection of selenium alleviated breast cancer-related lymphedema (BCRL). This secondary analysis aimed to explore the metabolic effects of selenium on patients with BCRL. Serum samples of the selenium-treated (SE, n = 15) or the placebo-controlled (CTRL, n = 14) groups were analyzed by ultra-high-performance liquid chromatography with Q-Exactive Orbitrap tandem mass spectrometry (UHPLC-Q-Exactive Orbitrap/MS). The SE group showed a lower ratio of extracellular water to segmental water (ECW/SW) in the affected arm to ECW/SW in the unaffected arm (arm ECW/SW ratio) than the CTRL group. Metabolomics analysis showed a valid classification at 2-weeks and 107 differential metabolites were identified. Among them, the levels of corticosterone, LTB4-DMA, and PGE3-which are known anti-inflammatory compounds-were elevated in the SE group. Pathway analysis demonstrated that lipid metabolism (glycerophospholipid metabolism, steroid hormone biosynthesis, or arachidonic acid metabolism), nucleotide metabolism (pyrimidine or purine metabolism), and vitamin metabolism (pantothenate and CoA biosynthesis, vitamin B6 metabolism, ascorbate and aldarate metabolism) were altered in the SE group compared to the CTRL group. In addition, xanthurenic acid levels were negatively associated with whole blood selenium level (WBSe) and positively associated with the arm ECW/SW. In conclusion, selenium IV injection improved the arm ECW/SW ratio and altered the serum metabolic profiles in patients with BCRL, and improved the anti-inflammatory process in lipid, nucleotide and vitamin pathways, which might alleviate the symptoms of BCRL.

Regression of human coronary artery plaque is associated with a high ratio of (18-hydroxy-eicosapentaenoic acid + resolvin E1) to leukotriene B4.

Inflammation in arterial walls leads to coronary artery disease (CAD). We previously reported that a high omega-3 fatty index was associated with prevention of progression of coronary atherosclerosis, a disease of chronic inflammation in the arterial wall. However, the mechanism of such benefit is unclear. The two main omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are precursors of specialized pro-resolving lipid mediators (SPMs)-resolvins and maresins-which actively resolve chronic inflammation. To explore whether SPMs are associated with coronary plaque progression, levels of SPMs and proinflammatory mediators (leukotriene B4 [LTB4 ] and prostaglandins) were measured using liquid chromatography-tandem mass spectrometry in 31 statin-treated patients with stable CAD randomized to either EPA and DHA, 3.36 g daily, or no EPA/DHA (control). Coronary plaque volume was measured by coronary computed tomographic angiography at baseline and at 30-month follow-up. Higher plasma levels of EPA+DHA were associated with significantly increased levels of two SPMs-resolvin E1 and maresin 1-and 18-hydroxy-eicosapentaenoic acid (HEPE), the precursor of resolvin E1. Those with low plasma EPA+DHA levels had a low (18-HEPE+resolvin E1)/LTB4 ratio and significant plaque progression. Those with high plasma EPA+DHA levels had either low (18-HEPE+resolvin E1)/LTB4 ratios with significant plaque progression or high (18-HEPE+resolvin E1)/LTB4 ratios with significant plaque regression. These findings suggest that an imbalance between pro-resolving and proinflammatory lipid mediators is associated with plaque progression and potentially mediates the beneficial effects of EPA and DHA in CAD patients.

Plasma Resolvin D2 to Leukotriene B4 Ratio Is Reduced in Diabetic Patients with Ischemic Stroke and Related to Prognosis.

BACKGROUND: Diabetes mellitus (DM) aggravates symptoms and prognosis of acute ischemic stroke (AIS), and inflammation plays an important role therein. Resolvin D2 (RvD2) is one of the specialized pro-resolving mediators (SPMs), while leukotriene B4 (LTB4) is a classic proinflammatory mediator. The ratio of RvD2 to LTB4 is an index of pro-resolving/proinflammatory balance. We aim to explore the role of RvD2/LTB4 ratio in ischemic stroke complicated with DM. METHODS: The plasma levels of RvD2 and LTB4 were analyzed by enzyme immunoassay in stroke patients with DM (DM + AIS group) or without DM (nonDM+AIS group). Patients were followed up at 90 days after stroke onset, and modified Rankin Score (mRS) was assessed. The association of RvD2/LTB4 ratio with stroke severity and prognosis was also analyzed. RESULTS: The plasma levels of RvD2 were positively correlated to LTB4. The RvD2/LTB4 ratio in DM + AIS group was lower than that in the nonDM+AIS group. No correlation was found between the RvD2/LTB4 ratio and infarct size or NIHSS score. The RvD2/LTB4 ratio at baseline was significantly lower in the poor prognosis group (mRS ≥ 3) than that in the good prognosis group (mRS ≤ 2). CONCLUSIONS: Our study indicated that the balance between pro-resolving and proinflammatory mediators was impaired by diabetes in ischemic stroke. The RvD2/LTB4 ratio may serve as a biomarker of prognosis for ischemic stroke.

Serum leukotriene B4 and hydroxyeicosatetraenoic acid in the prediction of pre-eclampsia.

INTRODUCTION: Pre-eclampsia (PE) affects 2-8% of pregnancies worldwide. Despite identification of numerous possible biomarkers, accurate prediction and early diagnosis of PE remain challenging. We examined the potential of leukotriene B4 (LTB4) and 15-hydroxyeicosatetraenoic acid (15(S)-HETE) as biomarkers of PE by comparing serum levels at three gestational age (GA) groups between normotensive pregnancies and asymptomatic women who subsequently developed preterm or term-PE. METHODS: This is a case-control study drawn from a prospective study of adverse pregnancy outcomes with serum samples collected at 19-24 weeks (n = 48), 30-34 weeks (n = 101) and 35-37 weeks (n = 54) GA. LTB4 and 15(S)-HETE levels were determined by ELISA. Serum level multiples of the median (MoM) were compared between normal and PE-pregnancies. Association between LTB4 and 15(S)-HETE and GA at delivery was investigated with Cox proportional-hazards models. RESULTS: Serum LTB4 levels were lower in women of East-Asian ethnicity, higher in women with PE history, and increased with GA in normotensive pregnancies, but not in PE. LTB4 was elevated at 19-24 weeks in women who developed preterm-PE. There was a negative association between LTB4 MoM and interval between sampling and delivery with PE at 19-24 weeks only. Serum 15(S)-HETE levels were not influenced by GA at testing and were elevated in women of South-Asian ethnicity. Median 15(S)-HETE levels were unchanged in preterm and term-PE at any GA. DISCUSSION: LTB4 was higher at 19-24 weeks in pregnancies that developed preterm-PE versus unaffected pregnancies, suggesting it is a potentially useful predictive marker of preterm PE in the second trimester.

Omega-3 polyunsaturated fatty acid supplementation improves lipid metabolism and endothelial function by providing a beneficial eicosanoid-pattern in patients with acute myocardial infarction: A randomized, controlled trial.

BACKGROUND & AIMS: Omega-3 polyunsaturated fatty acid (ω-3 PUFA) have been reported to have beneficial cardiovascular effects, but its mechanism of protection against acute myocardial infarction (AMI) who are under guideline-based therapy is not fully understood. Here, we used a metabolomic approach to systematically analyze the eicosanoid metabolites induced by ω-3 PUFA supplementation and investigated the underlying mechanisms. METHODS: Participants with AMI after successful percutaneous coronary intervention were randomized to 3 months of 2 g daily ω-3 PUFA and guideline-adjusted therapy (n = 30, ω-3 therapy) or guideline-adjusted therapy alone (n = 30, Usual therapy). Functional PUFA-derived eicosanoids in plasma were profiled by metabolomics. Clinical and laboratory tests were obtained before and 3 months after baseline and after the study therapy. RESULTS: By intent-to-treat analysis, the content of 11-HDoHE, 20-HDoHE and 16,17-EDP and that of epoxyeicosatetraenoic acids (EEQs), derived from docosahexaenoic acid and eicosapentaenoic acid, respectively, were significantly higher with ω-3 group than Usual therapy, whereas that of prostaglandin J2 (PGJ2) and leukotriene B4, derived from arachidonic acid, was significantly decreased. As compared with Usual therapy, ω-3 PUFA therapy significantly reduced levels of triglycerides (-6.3%, P < 0.05), apolipoprotein B (-4.9%, P < 0.05) and lipoprotein(a) (-37.0%, P < 0.05) and increased nitric oxide level (62.2%, P < 0.05). In addition, the levels of these variables were positively correlated with change in 16,17-EDP and EEQs content but negatively with change in PGJ2 content. CONCLUSIONS: ω-3 PUFA supplementation may improve lipid metabolism and endothelial function possibly by affecting eicosanoid metabolic status at a systemic level during convalescent healing after AMI. CLINICAL TRIAL REGISTRATION: URL: http://www.chictr.org.cn. Unique identifier: ChiCTR1900025859.

Elevated Levels of Anti-Inflammatory Eicosanoids and Monocyte Heterogeneity in Mycobacterium tuberculosis Infection and Disease.

Eicosanoids modulate both innate and adaptive immune responses in Mycobacterium tuberculosis (Mtb) infection and have been suggested as possible Host Directed Therapy (HDT) targets, but more knowledge of eicosanoid dynamics in Mtb infection is required. We investigated the levels and ratios of eicosanoid mediators and their cellular sources, monocyte subsets and CD4 T cells in Tuberculosis (TB) patients with various clinical states of Mtb infection. Patients consenting to prospective enrolment in a TB quality registry and biorepository, 16 with pulmonary TB (before and at-end-of treatment), 14 with extrapulmonary TB and 17 latently infected (LTBI) were included. Plasma levels of Prostaglandin E2 (PGE2), Lipoxin A4 (LXA4), and Leukotriene B4 (LTB4) were measured by enzyme-linked immunosorbent assay. Monocyte subsets and CD4 T cells and their expression of Cyclooxygenase-2 (COX-2), Prostaglandin receptor EP2 (EP2), and 5-Lipoxygenase (5-LOX) were analyzed by flow cytometry with and without Purified Protein Derivate (PPD)-stimulation. Pulmonary TB patients had elevated levels of the anti-inflammatory mediator LXA4 at diagnosis compared to LTBI (p < 0.01), while levels of PGE2 and LTB4 showed no difference between clinical states of Mtb infection. LTB4 was the only mediator to be reduced upon treatment (p < 0.05), along with the ratio LTB4/LXA4 (p < 0.01). Pulmonary TB patients had higher levels of total monocytes at diagnosis compared to end-of-treatment and LTBI (both p < 0.05), and a relative increase in the classical monocyte subset. All monocyte subsets had low basal expression of COX-2 and 5-LOX, which were markedly increased upon PPD stimulation. By contrast, the expression of EP2 was reduced upon stimulation. CD4 T cells expressed low basal COX-2 activity that increased modestly upon stimulation, whereas their basal expression of 5-LOX was considerable. In conclusion, the level of eicosanoids in plasma seem to vary between clinical states of Mtb infection. Mediators in the eicosanoid system are present in monocytes and CD4 T cells. The expression of eicosanoids in monocytes are responsive to mycobacterial stimulation independent of Mtb disease state, but subsets are heterogeneous with regard to eicosanoid-mediator expression. Further exploration of eicosanoid mediators as targets for HDT in TB are warranted.

Imbalanced serum levels of resolvin E1 (RvE1) and leukotriene B4 (LTB4) in patients with allergic rhinitis.

Timely and successful resolution of acute inflammation plays a crucial role in preventing the development of chronic airway inflammation in allergic rhinitis (AR). This study intends to assess the serum levels of pro-inflammatory leukotriene B4 (LTB4), anti-inflammatory mediators, including resolvin E1 (RvE1), RvD1, IL-10, and TGF-ß, besides mRNA expression level of G-protein coupled receptor 120 (GPR120) and peroxisome proliferator-activated receptor-γ (PPAR-γ) receptors in peripheral blood leukocytes of AR patients. Thirty-seven AR patients and thirty age- and gender-matched healthy subjects were enrolled in this study. The serum levels of LTB4, RvE1, RvD1, IL-10, and TGF-ß were measured using enzyme-linked immunosorbent assay (ELISA) technique, and the mRNA expression level of GPR120 and PPAR-γ was assessed by the real-time PCR method. The serum levels of RvE1 and LTB4 were significantly higher in patients with AR than in healthy subjects (P < 0.01 and P < 0.0001, respectively). However, a significantly lower ratio of RvE1 and RvD1 to LTB4 was found in patients with AR relative to healthy subjects (P < 0.05 and P < 0.0001, respectively). Likewise, the serum levels of both IL-10 and TGF-ß cytokines were significantly reduced in patients with AR compared to healthy subjects (P < 0.01 and P < 0.0001, respectively). Furthermore, the mRNA expression of PPAR-γ was significantly lower in patients with AR than in healthy subjects (P < 0.05). Our findings indicate that imbalanced pro-resolving lipid mediator RvE1 and pro-inflammatory LTB4 might contribute to the defective airway inflammation-resolution and subsequent progression toward chronic inflammation in AR patients.

Development of New Serum Biomarkers for Early Lymphedema Detection.

Background: Early lymphedema detection may reduce the symptoms and improve clinical outcomes. However, the lack of reliable serum biomarkers capable of predicting lymphedema development is a current medical problem. In this study, we investigated if serum levels of hyaluronic acid (HA) and leukotriene B4 (LTB4), two molecules involved in lymphedema development, may work as predictors of this condition. Methods and Results: A mouse model of acquired lymphedema was generated through ablation of tail dermal lymphatic network. Tail diameter was measured daily, and HA and LTB4 serum levels were analyzed before and during the development of lymphedema. We found increased serum levels of HA and reduced levels of LTB4 at early days before the appearance of lymphedema signs. Similar results were observed in the lymphedema tissue. Increased local and systemic inflammation was also detected at early time points. Moreover, the ratio LTB4/HA arises as the strongest predictor for lymphedema development. In fact, we found an inverse correlation in our model, where reduced LTB4/HA levels showed increased lymphedema signs. Conclusions: These findings suggest that serum ratio of LTB4/HA may be a useful biomarker to predict acquired lymphedema development, with potential to be used in clinical conditions such as breast cancer patients.

Pre-eclampsia is associated with reduced resolvin D1 and maresin 1 to leukotriene B4 ratios in the plasma.

PROBLEM: Omega-3 and omega-6 fatty acids can be endogenously converted into mediators with pro-inflammatory (eg, leukotriene B4/LTB4) or anti-inflammatory/pro-resolving activities (eg, resolvin D1/RvD1 and maresin 1/MaR1). Recent data indicate an imbalance of LTB4 and MaR1 levels in pre-eclampsia (PE), but the relative production of these mediators, including RvD1, and the role of these mediators in the disease pathogenesis remain unclear. Therefore, this study aimed to investigate the plasma levels of LTB4, RvD1, and MaR1 in pregnant women with or without PE and non-pregnant controls and their association with clinical/laboratory parameters of PE women. METHOD OF STUDY: LTB4, RvD1, and MaR1 plasma levels were measured by competitive enzyme immunoassay in 19 non-pregnant, 20 normotensive pregnant, and 21 PE women. RESULTS: Plasma concentrations of LTB4 were higher and RvD1 were lower in PE women than in normotensive pregnant women, who presented higher levels of LTB4 and similar levels of RvD1 to non-pregnant women. MaR1 levels did not differ among the groups. Pre-eclampsia women had decreased RvD1/LTB4 and MaR1/LTB4 ratios. Considering only the PE group, positive correlations were observed among all the mediators tested, between LTB4 and white blood cell count and between RvD1 and creatinine levels. However, all lipid mediators correlated negatively with body mass index before pregnancy. LTB4 also correlated negatively with maternal age. CONCLUSION: Our findings suggest that the PE state results in systemic overproduction of LTB4 in relation to RvD1 and MaR1, and that these lipid mediators may be involved with the disease pathogenesis.

Early and Sustained Increases in Leukotriene B4 Levels Are Associated with Poor Clinical Outcome in Ischemic Stroke Patients.

Leukotriene B4 (LTB4) has been implicated in ischemic stroke pathology. We examined the prognostic significance of LTB4 levels in patients with acute middle cerebral artery (MCA) infarction and their mechanisms in rat stroke models. In ischemic stroke patients with middle cerebral artery infarction, plasma LTB4 levels were found to increase rapidly, roughly doubling within 24 h when compared to initial post-stroke levels. Further analyses indicate that poor functional recovery is associated with early and more sustained increase in LTB4 rather than the peak levels. Results from studies using a rat embolic stroke model showed increased 5-lipoxygenase (5-LOX) expression in the ipsilateral infarcted cortex compared with sham control or respective contralateral regions at 24 h post-stroke with a concomitant increase in LTB4 levels. In addition, neutrophil influx was also observed in the infarcted cortex. Double immunostaining indicated that neutrophils express 5-LOX and leukotriene A4 hydrolase (LTA4H), highlighting the pivotal contributions of neutrophils as a source of LTB4. Importantly, rise in plasma LTB4 levels corresponded with an increase in LTB4 amount in the infarcted cortex, thereby supporting the use of plasma as a surrogate for brain LTB4 levels. Pre-stroke LTB4 loading increased brain infarct volume in tMCAO rats. Conversely, administration of the 5-LOX-activating protein (FLAP) inhibitor BAY-X1005 or B-leukotriene receptor (BLTR) antagonist LY255283 decreased the infarct volume by a similar extent. To conclude, targeted interruption of the LTB4 pathway might be a viable treatment strategy for acute ischemic stroke.

Promotion of Myofibroblast Differentiation and Tissue Fibrosis by the Leukotriene B4 -Leukotriene B4 Receptor Axis in Systemic Sclerosis.

OBJECTIVE: To investigate the role of the inflammatory lipid mediator leukotriene B4 (LTB4 ) and its receptor, BLT1, in the development and progression of systemic sclerosis (SSc). METHODS: Serum levels of LTB4 were compared in 64 patients with SSc and 80 healthy controls. Skin and lung tissue sections from patients with SSc and healthy donors were immunostained for leukotriene A4 hydrolase (LTA4 H), the critical enzyme for LTB4 synthesis, and BLT1, in combination with different cell markers. In mouse models of SSc using bleomycin or angiotensin II challenge or immunization with the DNA topoisomerase I, genetic or pharmacologic interruption of the LTB4 -BLT1 axis in mice was carried out to assess its effects on systemic disease features and myofibroblast markers. Immunoblotting was performed to examine the signaling pathway in fibroblasts and endothelial cells following stimulation with LTB4 or with serum from SSc patients. RESULTS: Serum LTB4 levels were 44.93% higher in patients with SSc than in matched healthy controls (mean ± SD 220.3 ± 74.75 pg/ml versus 152.0 ± 68.05 pg/ml; P < 0.0001), and this was associated with the patient subsets of SSc-associated interstitial lung disease and diffuse cutaneous SSc. Levels of LTA4 H and BLT1 were increased in lesional areas of the skin and lungs of SSc patients, and both were abundant in myofibroblasts and endothelial cells. Interruption of the LTB4 -BLT1 axis in mouse models of SSc significantly mitigated dermal and pulmonary fibrosis, with 54.00% and 52.65% fewer α-smooth muscle actin-positive myofibroblasts accumulating in the skin and lungs of mice, respectively, after bleomycin challenge. Immunoblotting of cultures with recombinant LTB4 -stimulated fibroblasts and endothelial cells or with serum from SSc patients showed that fibroblast-myofibroblast and endothelial-mesenchymal transitions were promoted via BLT1, and that this was dependent on activation of the phosphatidylinositol 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) pathway but independent of the release of transforming growth factor ß (TGFß) by fibroblasts or endothelial cells. CONCLUSION: The LTB4 -BLT1 axis may contribute to fibrosis in SSc by directly promoting myofibroblast differentiation via the PI3K/Akt/mTOR pathway, and this appears to operate independently of autocrine secretion of TGFß.

A possible relationship between Thromboxane B2 and Leukotriene B4 and the encapsulation of Dirofilaria repens worms in human subcutaneous dirofilariasis.

Human subcutaneous dirofilariosis has several clinical presentations. Many cases present as subcutaneous nodules, as a consequence of a local inflammatory reaction that encapsulates and destroys the worms. In addition, there are cases in which migrating worms located in the ocular area remain unencapsulated. In the present work, the levels of two pro-inflammatory eicosanoids, thromboxane B2 (TxB2) and leukotriene B4 (LTB4) are analysed by commercial Enzime-Linked immunosorbent assay (ELISA) in serum samples from 43 individuals, 28 diagnosed as having subcutaneous dirofilariasis presenting a subcutaneous nodule, five diagnosed as having dirofilariasis, in which the worms remained unencapsulated in the periphery of the eye, and ten healthy individuals living in a non-endemic area, used as controls. The worms were surgically removed, identifying Dirofilaria repens as the causative agent in all cases, by Polymerase Chain Reaction (PCR). Individuals with nodules showed significantly higher levels of TxB2 and LTB4 than healthy controls, whereas significant differences in LTB4 levels were observed between individuals with unencapsulated worms and healthy controls. It is speculated that the absence of LTB4 may contribute to the fact that worms remain unencapsulated as a part of immune evasion mechanisms.

Highly sensitive and specific LC-MS/MS method to determine endogenous leukotriene B4 levels in human plasma.

Aim: To develop a high sensitivity and specific analytical method to measure endogenous levels of leukotriene B4 (LTB4) in human plasma. Methodology: LC-MS/MS and ELISA. Results: An LC-MS/MS method was developed with a sensitivity of 1.0 pg/ml, and within and between batch precision of <16% and <13% RSD, respectively. Conclusion: We have developed a sensitive LC-MS/MS method that can detect endogenous LTB4 in human plasma. The LC-MS/MS method displayed correlation with a commercial LTB4 ELISA when analyzing in ex vivo ionophore-stimulated blood samples. For untreated plasma this correlation was lost. Endogenous LTB4 was shown to be unstable in plasma during storage at -20°C and subject to stereoisomer formation. Neither of the assays could quantify endogenous plasma LTB4 in samples stored for long term.

LC-MS/MS assay for the simultaneous determination of tocopherols, polyunsaturated fatty acids and their metabolites in human plasma and serum.

The role of vitamin E in both enzymatic and free radical-dependent metabolism of polyunsaturated fatty acids (PUFAs) has been well demonstrated. This study proposed a new LC-MS/MS method to quantify the main vitamin E forms, their metabolites and main PUFA species in human blood, since, at present, there are not procedures able to simultaneously determine these two classes of compounds. After the optimization of sample treatment and reverse-phase separation conditions, tandem mass spectrometry detection was evaluated experimenting both positive and negative electrospray ionisation modes. The procedure was also preliminarily adapted to assess five arachidonic acid-derived eicosanoids that could be under the influence of vitamin E function, such as LTB4 (leukotriene B4), 20-HETE (20-hydroxyeicosatetraenoic acid) and their ω-oxidation metabolites. After the validation study, the performance characteristics were confirmed analysing a certified reference material (SRM® 1950 - frozen human plasma by NIST). Finally, an application of the method in the analysis of lipid abnormalities of chronic kidney disease patients was shown.

Bronchoalveolar fluid and plasma inflammatory biomarkers in contemporary ARDS patients.

Purpose: Bronchoalveolar fluid (BALF) and plasma biomarkers are often endpoints in early phase randomized trials (RCTs) in acute respiratory distress syndrome (ARDS). With ARDS mortality decreasing, we analyzed baseline biomarkers in samples from contemporary ARDS patients participating in a prior RCT and compared these to historical controls. Materials and methods: Ninety ARDS adult patients enrolled in the parent trial. BALF and blood were collected at baseline, day 4 ± 1, and day 8 ± 1. Interleukins-8/-6/-1ß/-1 receptor antagonist/-10; granulocyte colony stimulating factor; monocyte chemotactic protein-1; tumour necrosis factor-α; surfactant protein-D; von Willebrand factor; leukotriene B4; receptor for advanced glycosylation end products; soluble Fas ligand; and neutrophil counts were measured. Results: Compared to historical measurements, our values were generally substantially lower, despite our participants being similar to historical controls. For example, our BALF IL-8 and plasma IL-6 were notably lower than in a 1999 RCT of low tidal volume ventilation and a 2007 biomarker study, respectively. Conclusions: Baseline biomarker levels in current ARDS patients are substantially lower than 6-20 years before collection of these samples. These findings, whether from ICU care changes resulting in less inflammation or from variation in assay techniques over time, have important implications for design of future RCTs with biomarkers as endpoints.

Resolution of inflammation in neuromyelitis optica spectrum disorders.

BACKGROUND: Neuromyelitis optica spectrum disorders (NMOSD) are a spectrum of neuroinflammatory disorders associated with autoimmune antibodies against aquaporin-4 (AQP4). Accumulating evidence suggests that inflammation is involved in NMOSD pathogenesis. Resolution of inflammation, which is a highly regulated process mediated by specialized pro-resolving lipid mediators (SPMs) is important to prevent over-responsive inflammation. Deficiency in resolution of inflammation may lead to or accelerates inflammatory diseases. However, whether resolution of inflammation is impaired in NMOSD is not known. The objective of this study was to analyze the levels of SPMs in the serum and cerebrospinal fluid (CSF) of NMOSD patients, and to explore the roles of SPMs in clinical features of NMOSD. METHODS: Thirty-five patients with NMOSD, 34 patients with multiple sclerosis, and 36 patients with non-inflammatory neurological diseases were enrolled in this study. Pro-resolving mediators including Annexin A1 (ANXA1) and resolvin D1 (RvD1), as well as pro-inflammatory lipid mediator leukotriene B4 (LTB4) levels were analyzed by enzyme-linked immunosorbent assay. Pro- and anti-inflammatory cytokines as well as chemokine levels were analyzed using cytometric beads array (CBA). RESULTS: Our results showed RvD1 levels were significantly decreased, whereas LTB4 levels were significantly increased in the CSF of NMOSD patients. AQP4-IgG titer was negatively correlated with RvD1 levels in the CSF of NMOSD patients. CONCLUSIONS: Decreased RvD1 levels indicate impaired resolution of inflammation in NMOSD patients. AQP4-IgG may contribute to increased inflammation and lead to unresolved inflammation in NMOSD.

Metabolic profiling of human plasma reveals the activation of 5-lipoxygenase in the acute attack of gouty arthritis.

Objective: Monosodium urate-induced inflammation plays a vital role in acute gout (AG). Inflammation is a multi-stage process involved in the acute release of arachidonic acid and its metabolites. However, the function of the metabolism of arachidonic acid and other polyunsaturated fatty acids in AG is not well understood. This study aimed to investigate the modification of polyunsaturated fatty acid metabolism by AG. Methods: Plasma samples from patients with an AG attack (n = 26) and gender-matched healthy controls (n = 26) were analysed by metabolic profiling of polyunsaturated fatty acids. The findings were further validated with a second cohort (n = 20 each group). The associated mechanisms were investigated in whole blood cells from the second cohort and neutrophils in vitro. Results: Plasma metabolic profiling revealed a significant increase in leukotriene B4 (LTB4) for AG patients in both cohorts. The increase in plasma LTB4 was accounted for by the dynamic balance between the activation of 5-lipoxygenase and CYP4F3, the former mediating the biosynthesis of LTB4 and the latter mediating its metabolism. This was supported by significantly increased transcriptional levels of 5-lipoxygenase and CYP4F3 in whole blood cells from AG patients compared with those of controls, and the uric acid-caused dose-relevant and time-dependent activation of 5-lipoxygenase and CYP4F3 at the transcriptional and molecular levels in vitro. Conclusion: Increased LTB4 in AG patients is mainly due to activation of 5-lipoxygenase. 5-Lipoxygenase inhibition may be of therapeutic value clinically.