Phospholipase A2 Research Articles

Essential trace element and phosphatidylcholine remodeling: Implications for body composition and insulin resistance

BackgroundRecent studies indicated that bioactive lipids of phosphatidylcholines (PCs) and lysophosphatidylcholines (LysoPCs) predict unhealthy metabolic phenotypes, but results remain inconsistent. To fill this knowledge gap, we investigated whether essential trace elements affect PC-Lyso PC remodeling pathways and the risk of insulin resistance (IR). MethodsAnthropometric and blood biochemical data (glucose, insulin, and lipoprotein-associated phospholipase A2 (Lp-PLA2)) were obtained from 99 adults. Blood essential/probably essential trace elements and lipid metabolites were respectively measured by inductively coupled plasma mass spectrometry (ICP-MS), and ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Result and ConclusionExcept for LysoPC (O-18:0/0:0), an inverse V shape was observed between body weight and PC and LysoPC species. A Pearson correlation analysis showed that essential/probably-essential metals (Se, Cu, and Ni: r=-0.4∼-0.7) were negatively correlated with PC metabolites but positively correlated with LysoPC (O-18:0/0:0) (Se, Cu, and Ni: r=0.85–0.64). Quantile-g computation showed that one quantile increase in essential metals was associated with a 2.16-fold increase in serum Lp-PLA2 (β=2.16 (95 % confidence interval (CI): 0.34, 3.98), p=0.023), which are key enzymes involved in PC/Lyso PC metabolism. An interactive analysis showed that compared to those with the lowest levels (reference), individuals with the highest levels of serum PCs (pooled, M2) and the lowest essential/probably essential metals (M1) were associated with a healthier body composition and had a 76 % decreased risk of IR (odds ratio (OR)=0.24 (95 % CI: 0.06, 0.90), p<0.05). In contrast, increased exposure to LysoPC(O-18:0/0:0) (M2) and essential metals (M2) exhibited an 8.22-times highest risk of IR (OR= 8.22 (2.07, 32.57), p<0.05) as well as an altered body composition. In conclusion, overexposure to essential/probably essential trace elements may promote an unhealthy body weight and IR through modulating PC/LysoPC remodeling pathways.

Correlation between lipoprotein-associated phospholipase A2 and poststroke mild cognitive impairment

ABSTRACT Objectives This study aimed to investigate the correlationbetween serum lipoprotein-associated phospholipase A2 (Lp-PLA2) and poststrokemild cognitive impairment (PSMCI). Methods The patients included in the study were divided into PSMCI (68 cases)and cognitively normal (CN) (218 cases) groups and followed up for six months.Demographic and clinical data were collected. A logistic regression analysiswas performed to determine whether Lp-PLA2 is an independent risk factor forPSMCI. Spearman’s correlation analysis was used to examine the correlationbetween Lp-PLA2 levels and Montreal CognitiveAssessment (MoCA) scores. A receiver operating characteristic (ROC) curveanalysis was performed to determine the diagnostic threshold value of Lp-PLA2for PSMCI. Results Serum Lp-PLA2 levels were significantly higherin the PSMCI group than in the CN group. The logistic regression analysisshowed that Lp-PLA2 was an independent risk factor for PSMCI (OR = 1.05, 95% CI= 1.03–1.07). Spearman’s correlation analysis revealed a significantcorrelation between the Lp-PLA2 levels and MoCA scores (R= -0.49). The area under the ROC curve forLp-PLA2 was 0.849, and the threshold value for PSMCI occurrence was 236.8 ng/ml. Conclusions Elevated serum Lp-PLA2 is an independent riskfactor for PSMCI and may serve as a potential biomarker for PSMCI.

Differentiating human phospholipase A2's activity toward phosphatidylinositol, phosphatidylinositol phosphate and phosphatidylinositol bisphosphate

Phospholipase A2's (PLA2's) constitute a superfamily of enzymes that hydrolyze the sn-2 fatty acyl chain on glycerophospholipids. We have previously reported that each PLA2 Type shows a unique substrate specificity for the molecular species it hydrolyzes, especially the acyl chain that is cleaved from the sn-2 position and to some extent the polar group. However, phosphatidylinositol (PI) and PI phosphates (PIPs) have not been as well studied as substrates as other phospholipids because the PIPs require adaptation of the standard analysis methods, but they are important in vivo. We determined the in vitro activity of the three major types of human PLA2's, namely the cytosolic (c), calcium-independent (i), and secreted (s) PLA2's toward PI, PI-4-phosphate (PI(4)P), and PI-4,5-bisphosphate (PI(4,5)P2). The in vitro assay revealed that Group IVA cPLA2 (GIVA cPLA2) showed relatively high activity toward PI and PI(4)P among the tested PLA2's; nevertheless, the highly hydrophilic headgroup disrupted the interaction between the lipid surface and the enzyme. GIVA cPLA2 and GVIA iPLA2 showed detectable activity toward PI(4,5)P2, but it appeared to be a poorer substrate for all of the PLA2's tested. Furthermore, molecular dynamics (MD) simulations demonstrated that Thr416 and Glu418 of GIVA cPLA2 contribute significantly to accommodating the hydrophilic head groups of PI and PI(4)P, which could explain some selectivity for PI and PI(4)P. These results indicated that GIVA cPLA2 can accommodate PI and PI(4)P in its active site and hydrolyze them, suggesting that the GIVA cPLA2 may best account for the PI and PIP hydrolysis in living cells.

Phospholipid metabolism-related genotypes of PLA2R1 and CERS4 contribute to nonobese MASLD.

Abnormal phospholipid metabolism is linked to metabolic dysfunction-associated steatotic liver disease (MASLD) development and progression. We aimed to clarify whether genetic variants of phospholipid metabolism modify these relationships. This case-control study consecutively recruited 600 patients who underwent MRI-based proton density fat fraction examination (240 participants with serum metabonomics analysis, 128 biopsy-proven cases) as 3 groups: healthy control, nonobese MASLD, and obese MASLD, (n = 200 cases each). Ten variants of phospholipid metabolism-related genes [phospholipase A2 Group VII rs1805018, rs76863441, rs1421378, and rs1051931; phospholipase A2 receptor 1 (PLA2R1) rs35771982, rs3828323, and rs3749117; paraoxonase-1 rs662 and rs854560; and ceramide synthase 4 (CERS4) rs17160348)] were genotyped using SNaPshot. The T-allele of CERS4 rs17160348 was associated with a higher risk of both obese and nonobese MASLD (OR: 1.95, 95% CI: 1.20-3.15; OR: 1.76, 95% CI: 1.08-2.86, respectively). PLA2R1 rs35771982-allele is a risk factor for nonobese MASLD (OR: 1.66, 95% CI: 1.11-1.24), moderate-to-severe steatosis (OR: 3.24, 95% CI: 1.96-6.22), and steatohepatitis (OR: 2.61, 95% CI: 1.15-3.87), while the paraoxonase-1 rs854560 T-allele (OR: 0.50, 95% CI: 0.26-0.97) and PLA2R1 rs3749117 C-allele (OR: 1.70, 95% CI: 1.14-2.52) are closely related to obese MASLD. After adjusting for sphingomyelin level, the effect of the PLA2R1 rs35771982CC allele on MASLD was attenuated. Furthermore, similar effects on the association between the CERS4 rs17160348 C allele and MASLD were observed for phosphatidylcholine, phosphatidic acid, sphingomyelin, and phosphatidylinositol. The mutations in PLA2R1 rs35771982 and CERS4 rs17160348 presented detrimental impact on the risk of occurrence and disease severity in nonobese MASLD through altered phospholipid metabolism.

Effects of grain intervention on hypothalamic function and the metabolome of blood and milk in dairy cows

BackgroundThe hypothalamus plays a crucial role in the health and productivity of dairy cows, yet studies on its functionality and its impact on peripheral circulation in these animals are relatively scarce, particularly regarding dietary interventions. Therefore, our study undertook a comprehensive analysis, incorporating both metabolomics and transcriptomics, to explore the effects of a grain-based diet on the functionality of the hypothalamus, as well as on blood and milk in dairy cows.ResultsThe hypothalamic metabolome analysis revealed a significant reduction in prostaglandin E2 (PGE2) level as a prominent response to the grain-based diet introduction. Furthermore, the hypothalamic transcriptome profiling showed a notable upregulation in amino acid metabolism due to the grain-based diet. Conversely, the grain-based diet led to the downregulation of genes involved in the metabolic pathway from lecithin to PGE2, including phospholipase A2 (PLA2G4E, PLA2G2A, and PLA2G12B), cyclooxygenase-2 (COX2), and prostaglandin E synthase (PTGES). Additionally, the plasma metabolome analysis indicated a substantial decrease in the level of PGE2, along with a decline in adrenal steroid hormones (tetrahydrocortisol and pregnenolone) following the grain-based diet introduction. Analysis of the milk metabolome showed that the grain-based diet significantly increased uric acid level while notably decreasing PGE2 level. Importantly, PGE2 was identified as a critical metabolic marker in the hypothalamus, blood, and milk in response to grain intervention. Correlation analysis demonstrated a significant correlation among metabolic alterations in the hypothalamus, blood, and milk following the grain-based diet.ConclusionsOur findings suggest a potential link between hypothalamic changes and alterations in peripheral circulation resulting from the introduction of a grain-based diet.

Deep analysis of total serum N-glycome suggests glyco-signatures for phospholipase A2 receptor 1-related idiopathic membranous nephropathy diagnosis

Idiopathic membranous nephropathy (IMN) is an antibody-mediated and kidney-specific autoimmune disease, with the antigen phospholipase A2 receptor 1 (PLA2R1) accounting for approximately 70% of IMN cases. Although a variety of new podocyte target antigens and their autoantibodies have been identified, they are still of limited diagnostic and therapeutic value due to lack of high specificity and sensitivity. N-glycans play vital roles in renal system and their pathobiological relevance has become increasingly recognized in many kidney diseases, but not fully explored in IMN. To find possible glyco-signatures for PLA2R1-related IMN diagnosis, we herein established a comprehensive workflow for total serum N-glycome analysis based on our recently developed mass spectrometry (MS)-based N-glycan purification method, named Ultrafast Glycoprotein Immobilization for Glycan extraction (UltraGIG). A total of 191 N-glycans were identified from IMN patients, representing the largest N-glycome dataset in IMN. Compared to healthy controls, up-regulation of sialylation and core-fucosylation as well as down-regulation of galactosylation were observed in PLA2R1-positive IMN patients, and up-regulation of hyper-galactosylation was specific for PLA2R1-negative IMN patients. A six-glycan marker panel consisting of H4N3S1, H4N3F1, H6N4S2, H6H5F1S2, H6N5 and H6N6F1S1, was proposed to aid in the accurate diagnosis of PLA2R1-related IMN, which provided new insights into IMN biomarker study. SignificancePLA2R1-related IMN is a kidney-specific autoimmune disease with a high risk of developing end-stage renal disease (ESRD) and even kidney failure. Current biomarkers are still of limited diagnostic and therapeutic value due to lack of high specificity and sensitivity. An in-depth MS analysis of total serum N-glycome of PLA2R1-related IMN patients was conducted for the first time. We generated the largest dataset of serum N-glycome for IMN to date, and proposed a novel six-glycan marker panel that may help the accurate diagnosis of PLA2R1-related IMN.

Protection of blood-brain barrier by endothelial DAPK1 deletion after stroke

Death-associated protein kinase (DAPK) 1 is a critical mediator for neuronal cell death in cerebral ischemia, but its role in blood-brain barrier (BBB) disruption is incompletely understood. Here, we found that endothelial-specific deletion of Dapk1 using Tie2 Cre protected the brain of Dapk1fl/fl mice against middle cerebral artery occlusion (MCAO), characterized by mitigated Evans blue dye (EBD) extravasation, reduced infarct size and improved behavior. In vitro experiments also indicated that DAPK1 deletion inhibited oxygen-glucose deprivation (OGD)-induced tight junction alteration between cerebral endothelial cells (CECs). Mechanistically, we revealed that DAPK1-DAPK3 interaction activated cytosolic phospholipase A2 (cPLA2) in OGD-stimulated CECs. Our results thus suggest that inhibition of endothelial DAPK1 specifically prevents BBB damage after stroke.

Quantification of urinary podocyte-derived migrasomes for the diagnosis of kidney disease.

Migrasomes represent a recently uncovered category of extracellular microvesicles, spanning a diameter range of 500 to 3000nm. They are emitted by migrating cells and harbour a diverse array of RNAs and proteins. Migrasomes can be readily identified in bodily fluids like serum and urine, rendering them a valuable non-invasive source for disease diagnosis through liquid biopsy. In this investigation, we introduce a streamlined and effective approach for the capture and quantitative assessment of migrasomes, employing wheat germ agglutinin (WGA)-coated magnetic beads and flow cytometry (referred to as WBFC). Subsequently, we examined the levels of migrasomes in the urine of kidney disease (KD) patients with podocyte injury and healthy volunteers using WBFC. The outcomes unveiled a substantial increase in urinary podocyte-derived migrasome concentrations among individuals with KD with podocyte injury compared to the healthy counterparts. Notably, the urinary podocyte-derived migrasomes were found to express an abundant quantity of phospholipase A2 receptor (PLA2R) proteins. The presence of PLA2R proteins in these migrasomes holds promise for serving as a natural antigen for the quantification of autoantibodies against PLA2R in the serum of patients afflicted by membranous nephropathy. Consequently, our study not only pioneers a novel technique for the isolation and quantification of migrasomes but also underscores the potential of urinary migrasomes as a promising biomarker for the early diagnosis of KD with podocyte injury.

Gender-related and PUFA-related differences in lipoprotein-associated phospholipase A2 levels in patients with type 2 diabetes and atherosclerotic cardiovascular disease.

Lipoprotein-associated phospholipase A2 (Lp-PLA2) may play an important role in the development of atherosclerotic cardiovascular disease (ASCVD). Increased plasma levels of Lp-PLA2 may predict future cardiovascular (CV) events in type 2 diabetes (T2D). The potential beneficial effects of polyunsaturated fatty acids (PUFA) on ASCVD have been widely investigated. However, the impact of different PUFA concentrations on Lp-PLA2 remains uncertain. We sought to determine the intergender differences in a population of patients with both T2D and ASCVD regarding Lp-PLA2 mass and the association between Lp-PLA2 mass and plasma levels of PUFA. In this cross-sectional study, we measured the Lp-PLA2 mass, PUFA concentrations and inflammatory markers in 74 patients (49 males and 25 females) with T2D and ASCVD. In this very high-risk population, males had, on average, 33.6% higher levels of Lp-PLA2 than females. The Lp-PLA2 mass was positively associated with interleukin 6 (IL-6) (r = 0.27, p = 0.019), creatinine (r = 0.29, p = 0.03) and triglyceride levels (r = 0.41, p = 0.002). Additionally, male gender and higher levels of triglycerides, leptin, oxidized low-density lipoprotein (oxLDL), and intercellular adhesion molecule 1 (ICAM-1) were independent predictors for an increased Lp-PLA2. Moreover, arachidonic acid (AA) negatively correlated with Lp-PLA2 (r = -0.26, p = 0.024), which was especially apparent in the female subgroup. In the population of patients with ASCVD and T2D, males present with higher plasma levels of Lp-PLA2 than females. Additionally, higher plasma levels of AA were associated with lower Lp-PLA2 levels. Our findings support the utilization of Lp-PLA2 as a novel biomarker in ASCVD risk assessment in a very high CV risk population.

Inhibiting arachidonic acid generation mitigates aging-induced hyperinsulinemia and insulin resistance in mice

BackgroundAging-related type 2 diabetes (T2DM) is characterized by hyperinsulinemia, insulin resistance, and β-cell dysfunction. However, the underlying molecular mechanisms remain to be unclear. MethodsWe conducted non-targeted metabolomics to compare human serum samples from young adults (YA), elderly adults (EA), and elderly adults with diabetes (EA+DM) of Chinese population. Adult mice and aged mice were intragastrically administered with varespladib every day for two weeks and metabolic characteristics were monitored. Serum levels of arachidonic acid, insulin, and C-peptide, as well as serum activity of secretory phospholipase A2 (sPLA2) were detected in mice. Mouse islet perfusion assays were used to assess insulin secretion ability. Phosphorylated AKT levels were measured to evaluate insulin sensitivities of peripheral tissues in mice. ResultsNon-targeted metabolomics analysis of human serum samples revealed differential metabolic signatures among the YA, EA, and EA+DM groups. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed significant enhancement of arachidonic acid metabolism and glycerophospholipid metabolism in the EA group compared with the YA group. Further analysis identified two metabolic fluxes that favored the accumulation of arachidonic acid in the elderly. Increased levels of arachidonic acid were also confirmed in aged mice with hyperinsulinemia and insulin resistance, together with subsequent glucose intolerance. Conversely, inhibiting the generation of arachidonic acid with varespladib, an inhibitor of sPLA2, reduced aging-associated diabetes by improving hyperinsulinemia and hepatic insulin resistance in aged mice but not in adult mice. Islet perfusion assays also showed that varespladib treatment suppressed the enhanced insulin secretion observed in aged islets. ConclusionsCollectively, our findings uncover that arachidonic acid serves as a metabolic hub in Chinese elderly population. Our results also suggest that arachidonic acid plays a fundamental role in regulating β-cell function during aging and point to a novel therapy for aging-associated diabetes.

Copy number deletion of PLA2G4A affects the susceptibility and clinical phenotypes of schizophrenia

Phospholipase A2(PLA2) superfamily is recognized as being involved in the pathogenesis of schizophrenia by affecting lipid homeostasis in cell membranes. We hypothesized that PLA2 gene copy number variation (CNV) may affect PLA2 enzyme expression and be associated with schizophrenia risk. This study indicated that in the discovery stage, an increased copy number of PLA2G6 and the deletion of PLA2G3, PLA2G4A, PLA2G4F and PLA2G12F was associated with increased risk of schizophrenia. CNV segments involving six PLA2 genes were detected in publicly available datasets, including two deletion segments specific to the PLA2G4A gene. The relationship between the deletion of PLA2G4A and susceptibility to schizophrenia was then reaffirmed in the validation group of 806 individuals. There was a significant correlation between PLA2G4A deletion and the symptoms of poverty of thought in male patients and erotomanic delusion in females. Furthermore, ELISA results demonstrate a significant decrease in peripheral blood cytosolic PLA2(cPLA2) levels in patients with the PLA2G4A deletion genotype compared to those with normal and copy number duplicate genotypes. These data suggest that the functional copy number deletion in the PLA2G4A gene is associated with the risk of schizophrenia and clinical phenotypes by reducing the expression of cPLA2, which may be an indicator of susceptibility to schizophrenia.

Effect of flavonoid-rich fraction of Pleiocarpa mutica leaves on phospholipase A2 activity

Pleiocarpa mutica (Apocynaceae) is a pharmaceutical plant investigated to identify the usefulness and efficacy of the shrubs in the treatment of various ailments. Also, flavonoids are polypenolic compounds frequently found in nature and are divided into flavones, anthocyanidins, isoflavones, catechins, flavonols, chalcones, and flavonones based on the structure of their chemicals. Hence, fresh leaves of Pleiocarpa mutica were collected from Ugbene-Ajima, Uzo-Uwani Local Government Area, Enugu State, Nigeria. The extraction of a flavonoid-rich fraction of P. mutica leaves was conducted by dissolving a certain amount of crude extract in 20 mL of 10% H2SO4 in a tiny flask and then heating the mixture in a water bath for 30 minutes at 100 °C to initiate hydrolysis. However, quantitative phytochemical analysis of the P. mutica flavonoid-rich fraction was carried out by utilizing standard conventional protocols. Newly drawn human blood samples were centrifuged for 10 minutes at 3,000 rpm, with the supernatant (plasma) being disposed of. After being measured and reconstituted as a 40% (v/v) suspension with phosphate-buffered saline, the red blood cells were rinsed three times with an equivalent volume of normal saline. The fraction substantially (p &lt; 0.05) reduced the activity of phospholipase A2 in a concentration-dependent approach when compared to the standard drug (prednisolone), with a range of 0.2 mL to 1.0 mL reducing the amount of the enzyme by 47.58% to 63.61%. These results showed that the flavonoid-rich fraction of Pleiocarpa mutica leaves is potent in curtailing the inflammatory response through inhibition of phospholipase A2 activity.

Sex differences in cardiac ferroptosis after acute myocardial infarction in wild type and aryl hydrocarbon receptor knockout mice

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): MICIN/Agencia Estatal de Investigación (DOI: 10.13039/50110001103) (NextGeneration, EU/PRTR) Background and Purpose Ferroptosis is a new regulated programmed cell death pathway, driven by iron-dependent phospholipid peroxidation, that plays an important role in the development of cardiovascular diseases. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor of the basic Helix-Loop-Helix-PER-ARNT-SIM superfamily. Upon ligand binding, AhR translocates into the nucleus and dimerizes with the AhR nuclear translocator; the heterodimer then binds to dioxin-response elements located in the promoter region of receptor-regulated genes, most of which are involved in xenobiotic metabolism. Beyond its role in metabolizing exogenous toxins as part of an adaptive chemical response, it is well known that AhR is activated by endogenous ligands and it has been postulated that AhR has important functions in physiological and/or pathological conditions. Here we studied sex differences in cardiac ferroptosis after acute myocardial infarction (AMI) in mice and the implication of defective AhR signalling on this process. Methods and Results AMI was induced in 8–10-weeks-old males and females AhR+/+ and AhR-/- mice by ligation of the left anterior descending coronary artery. Animal care and experimental procedures followed the principles of animal care (NIH publication Nº85-23 revised 1985) and the guidelines for ethical care of experimental animals of the European Union (2010/63/EU). Survival analysis showed that 16% of AhR+/+male mice and 14% of AhR+/+ female mice died 72 h after AMI surgery whereas the mortality was 100% in AhR-/-male mice and only 17% in AhR-/- female mice group. The treatment of AhR-/- AMI male mice with ferrostatin (1 mg/kg i.p) increased survival to 40%. Immunofluorescence analysis of cardiac staining levels of 8-hydroxy-2’-deoxyguanosine revealed higher oxidative stress in AhR+/+AMI male mice compared with AhR+/+AMI females, 24 h after surgery. The absence of AhR in AMI males showed an increased oxidative stress that was similar to that obtained in AMI AhR+/+ males but significantly greater than that observed in AhR-/- AMI females. Finally, analysis of differential expressions of classical genes related to ferroptosis in AhR-/- AMI male and AMI female mice, 24 h after surgery, showed, only in males, a reduced expression of ferritin heavy chain 1 and ferroportin, and an increased expression of phospholipase A2. Conclusion Our results show that loss of AhR in males but not in females favours the ferroptosis process associated with myocardial ischemia, highlighting a possible role for this nuclear receptor in cardiac remodelling and survival after AMI.

The Prevalence, Characteristics, and Putative Mechanisms of Dual Antigen-Positive Membranous Nephropathy: The Underestimated Condition.

Following the discovery of podocyte phospholipase A2 receptor and thrombospondin type-1 domain-containing 7A, various potential target antigens for membranous nephropathy (MN) have been reported one after another. MN target antigens have now been identified in a significant proportion of patients, and a new classification framework classifies patients with MN based on the detected antigen and associated disease phenotype. A serology-based approach that does not require a histological diagnosis for patients suspected of having MN has also been proposed. However, there have been cases in which dual positivity for MN antigens and/or corresponding antibodies has been shown. Importantly, some of them showed a transition of the affected patient's immune responses to MN antigens, suggesting that serological diagnosis changes depending on the timing of the analysis. In this review, we provide detailed information on these cases and present an overview of our recent understanding of their putative mechanisms involved in these cases. Greater awareness is required to adequately recognize and develop appropriate therapeutic strategies for this condition.

Online monitoring of continuous aqueous two-phase flotation (ATPF) for the development of an autonomous control strategy

Aqueous two-phase flotation (ATPF) is a separation technique for isolating biological products such as enzymes from crude complex biosuspensions. The continuous operation mode of ATPF allows high throughput while maintaining a high separation efficiency. In this work, a laboratory plant for continuous ATPF with integrated online measurement technology is presented and ATPF experiments with the model enzyme phospholipase A2 are performed. Three electrical conductivity probes allow real time and spatially resolved characterization of phase mixing in the flotation tank caused by rising bubbles. UV/Vis spectroscopy is used to measure the enzyme concentration online at the top phase outlet. The equilibrium concentrations in the top and bottom phase are linearly dependent on the feed concentration, revealing a constant partition coefficient. The experimental results of this work provide the basis for the development of an autonomous feedback controller for the continuous ATPF process.

Investigation of potential effects of quercetin on COVID-19 treatment: a systematic review of randomized controlled trials

Objectives: The COVID-19 pandemic has rapidly become a global health crisis. Currently, there are no proven, reliable, specific treatments for COVID-19. Alongside drug interventions, supportive treatments are implemented during the disease. Quercetin, recognized for its antiviral, anti-inflammatory, anti-aging, and antioxidant properties, is under evaluation in this study for its potential impact on preventing, influencing the course, and mitigating the severity of COVID-19. Methods: A thorough search was conducted across scientific databases, including PubMed, Embase, Web of Science, SAGEpub, Copernicus, Cochrane Library, ScienceDirect, Elsevier, Scopus, Google Scholar, EBSCOhost, Crossref, Ovid-LWW, and DergiPark databases, between 1 November 2021 and 1 April 2022 to ensure a comprehensive inclusion of relevant studies. Results: Thirteen randomized controlled clinical trials (five published, eight unpublished) were identified. Existing literature supports quercetin’s role as a potent free radical scavenger with robust antioxidant properties. It exhibits anti-inflammatory characteristics by inhibiting lipid peroxidation and restraining pro-inflammatory enzymes such as lipoxygenase and phospholipase A2. Scholarly discourse suggests that quercetin supplementation within the 500-1500 mg range leads to favorable outcomes, including quicker patient discharge, reduced inflammation, increased respiratory rate, accelerated viral clearance, and an improved disease prognosis. However, it is noted that intervention durations vary across studies. Conclusions: The analysis of the studies suggested that quercetin is a promising therapeutic agent that can cause a decrease in disease symptoms, frequency of hospitalization, hospital stay, need for non-invasive oxygen treatment, need for intensive care, and mortality. Nonetheless, more clinical studies are needed to better understand quercetin’s curative effects on COVID-19 infection.

IL-6 inhibition with clazakizumab in patients receiving maintenance dialysis: a randomized phase 2b trial

Inflammation mediated by interleukin-6 (IL-6) is strongly associated with cardiovascular risk. Here we evaluated clazakizumab, a monoclonal antibody targeting the IL-6 ligand, in a phase 2b dose-finding study. Adults with cardiovascular disease and/or diabetes receiving maintenance dialysis with high-sensitivity C-reactive protein (hs-CRP) ≥ 2 mg l−1 at baseline were randomized to receive clazakizumab (2.5 mg, 5 mg or 10 mg, n = 32 per dose group) or placebo (n = 31) every 4 weeks. The primary endpoint was the change from baseline in hs-CRP to week 12, expressed as the geometric mean ratio. Clazakizumab treatment signficantly reduced serum hs-CRP concentrations at week 12 by 86%, 90% and 92% relative to placebo in patients randomized to 2.5 mg, 5 mg or 10 mg clazakizumab, respectively (all P < 0.0001), meeting the primary outcome. With regard to secondary endpoints, clazakizumab treatment reduced serum fibrinogen, amyloid A, secretory phospholipase A2, and lipoprotein(a) concentrations, as well as increased mean serum albumin concentrations at 12 weeks, relative to placebo. The proportion of patients who achieved hs-CRP < 2.0 mg l−1 was 79%, 82% and 79% in the 2.5 mg, 5 mg and 10 mg clazakizumab groups, respectively, compared with 0% of placebo-treated patients. With regard to safety, no cases of sustained grade 3 or 4 thrombocytopenia or neutropenia were observed. Serious infections were seen with similar frequency in the placebo, clazakizumab 2.5 mg and clazakizumab 5 mg groups, but were numerically more frequent in the clazakizumab 10 mg group. The results of this trial indicate that in patients receiving maintenance dialysis, clazakizumab reduced inflammatory biomarkers associated with cardiovascular events. ClinicalTrials.gov registration: NCT05485961.

Effects of sEH inhibition on the eicosanoid and cytokine storms in SARS-CoV-2-infected mice.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection involves an initial viral infection phase followed by a host-response phase that includes an eicosanoid and cytokine storm, lung inflammation and respiratory failure. While vaccination and early anti-viral therapies are effective in preventing or limiting the pathogenic host response, this latter phase is poorly understood with no highly effective treatment options. Inhibitors of soluble epoxide hydrolase (sEH) increase levels of anti-inflammatory molecules called epoxyeicosatrienoic acids (EETs). This study aimed to investigate the impact of sEH inhibition on the host response to SARS-CoV-2 infection in a mouse model with human angiotensin-converting enzyme 2 (ACE2) expression. Mice were infected with SARS-CoV-2 and treated with either vehicle or the sEH inhibitor 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU). At day 5 post-infection, SARS-CoV-2 induced weight loss, clinical signs, a cytokine storm, an eicosanoid storm, and severe lung inflammation with ~50% mortality on days 6-8 post-infection. SARS-CoV-2 infection induced lung expression of phospholipase A2 (PLA2), cyclooxygenase (COX) and lipoxygenase (LOX) pathway genes, while suppressing expression of most cytochrome P450 genes. Treatment with the sEH inhibitor TPPU delayed weight loss but did not alter clinical signs, lung cytokine expression or overall survival of infected mice. Interestingly, TPPU treatment significantly reversed the eicosanoid storm and attenuated viral-induced elevation of 39 fatty acids and oxylipins from COX, LOX and P450 pathways, which suggests the effects at the level of PLA2 activation. The suppression of the eicosanoid storm by TPPU without corresponding changes in lung cytokines, lung inflammation or mortality reveals a surprising dissociation between systemic oxylipin and cytokine signaling pathways during SARS-CoV-2 infection and suggests that the cytokine storm is primarily responsible for morbidity and mortality in this animal model.

Correlation of LP-PLA2 and MMP-9 with the occurrence of early neurological deterioration in patients with acute ischemic stroke.

Early neurological deterioration is a common complication of acute ischemic stroke (AIS), which aggravates symptoms, worsens the condition, and counteracts the benefits of clinical treatment. The aim of this paper was to analyze the correlation between lipoprotein-associated phospholipase A2 (Lp-PLA2), matrix metalloproteinase-9 (MMP-9), and the occurrence of early neurological deterioration (END) in patients with AIS and to explore the clinical prediction of END by the combination of the 2 assays for the clinical prediction of END. A total of 500 AIS patients admitted to our hospital from October 2022 to October 2023 were included as study subjects, and the clinical data of all AIS patients were collected and organized to detect the levels of Lp-PLA2 and MMP-9. Categorized into END and non-END groups according to whether END occurred within 7 days of the onset of AIS, and comparing the clinical baseline data and laboratory index levels of the 2 groups. Logistic regression analysis was performed to determine the independent predictors of END, and the predictive effects of Lp-PLA2 and MMP-9 levels on END were assessed by subject work characteristics (ROC) curves. END occurred in 111 (22.2%) of 500 AIS patients. Multivariate logistic regression analysis showed that diabetes (OR 2.717, 95% CI:1.53-4.81, P < .001), baseline NIHSS score (OR 1.65, 95% CI:1.41-1.94, P < .001), Lp-PLA2 (OR 1.07, 95% CI:1.05-1.09, P < .001) and MMP-9 (OR 1.12, 95% CI:1.09-1.16, P < .001) levels were independent influences on the occurrence of END in patients with AIS after correcting for confounders. ROC curve analysis showed that Lp-PLA2, MMP-9, and a combination of both predicted END with an area under the curve was 0.730, 0.763, and 0.831, respectively, and the area under the curve for the combination of both predicting END was significantly higher than that for any of the inflammatory markers alone (P < .05). Both inflammatory markers, Lp-PLA2 and MMP-9, were independent predictors of the development of END in patients with AIS, and the combination of the two had a higher predictive value.

Lipidomics of phospholipase A2 reveals exquisite specificity in macrophages

Phospholipase A2 (PLA2) constitutes a superfamily of enzymes that hydrolyze phospholipids at their sn-2 fatty acyl position. Our laboratory has demonstrated that PLA2 enzymes regulate membrane remodeling and cell signaling by their specificity toward their phospholipid substrates at the molecular level. Recent in vitro studies show that each type of PLA2, including Group IVA cytosolic PLA2 (cPLA2), Group V secreted PLA2 (sPLA2), Group VIA calcium independent PLA2 (iPLA2) and Group VIIA lipoprotein-associated PLA2, also known as platelet-activating factor acetyl hydrolase, can discriminate exquisitely between fatty acids at the sn-2 position. Thus, these enzymes regulate the production of diverse PUFA precursors of inflammatory metabolites. We now determined PLA2 specificity in macrophage cells grown in cell culture, where the amounts and localization of the phospholipid substrates play a role in which specific phospholipids are hydrolyzed by each enzyme type. We used PLA2 stereospecific inhibitors in tandem with a novel UPLC-MS/MS-based lipidomics platform to quantify more than a thousand unique phospholipid molecular species demonstrating cPLA2, sPLA2, and iPLA2 activity and specificity toward the phospholipids in living cells. The observed specificity follows the in vitro capability of the enzymes and can reflect the enrichment of certain phospholipid species in specific membrane locations where particular PLA2’s associate. For assaying, we target 20:4-PI for cPLA2, 22:6-PG for sPLA2, and 18:2-PC for iPLA2. These new results provide great insight into the physiological role of PLA2 enzymes in cell membrane remodeling and could shed light on how PLA2 enzymes underpin inflammation and other lipid-related diseases.