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Background and Purpose: Autophagy is a protective factor for controlling neuronal damage, while necroptosis promotes neuroinflammation after spinal cord injury (SCI). DADLE (D‐Ala2, D‐Leu5]‐enkephalin) is a selective agonist for delta (δ) opioid receptor and has been identified as a promising drug for neuroprotection. The aim of this study was to investigate the mechanism/s by which DADLE causes locomotor recovery following SCI. Experimental approach: Spinal cord contusion model was used and DADLE was given by i.p. (16 mg·kg−1) in mice for following experiments. Motor function was assessed by footprint and Basso mouse scale (BMS) score analysis. Western blotting used to evaluate related protein expression. Immunofluorescence showed the protein expression in each cell and its distribution. Network pharmacology analysis was used to find the related signalling pathways. Key Results: DADLE promoted functional recovery after SCI. In SCI model of mice, DADLE significantly increased autophagic flux and inhibited necroptosis. Concurrently, DADLE restored autophagic flux by decreasing lysosomal membrane permeabilization (LMP). Additionally, chloroquine administration reversed the protective effect of DADLE to inhibit necroptosis. Further analysis showed that DADLE decreased phosphorylated cPLA2, overexpression of cPLA2 partially reversed DADLE inhibitory effect on LMP and necroptosis, as well as the promotion autophagy. Finally, AMPK/SIRT1/p38 pathway regulating cPLA2 is involved in the action DADLE on SCI and naltrindole inhibited DADLE action on δ receptor and on AMPK signalling pathway. Conclusion and Implication: DADLE causes its neuroprotective effects on SCI by promoting autophagic flux and inhibiting necroptosis by decreasing LMP via activating δ receptor/AMPK/SIRT1/p38/cPLA2 pathway. [ABSTRACT FROM AUTHOR]

Physiologically, renal medullary cells are surrounded by a hyperosmolar interstitium. However, different pathological situations can induce abrupt changes in environmental osmolality, causing cell stress. Therefore, renal cells must adapt to survive in this new condition. We previously demonstrated that, among the mechanisms involved in osmoprotection, renal cells upregulate triglyceride biosynthesis (which helps preserve glycerophospholipid synthesis and membrane homeostasis) and cyclooxygenase‐2 (which generates prostaglandins from arachidonic acid) to maintain lipid metabolism in renal tissue. Herein, we evaluated whether hyperosmolality modulates phospholipase A2 (PLA2) activity, leading to arachidonic acid release from membrane glycerophospholipid, and investigated its possible role in hyperosmolality‐induced triglyceride synthesis and accumulation. We found that hyperosmolality induced PLA2 expression and activity in Madin‐Darby canine kidney cells. Cytosolic PLA2 (cPLA2) inhibition, but not secreted or calcium‐independent PLA2 (sPLA2 or iPLA2, respectively), prevented triglyceride synthesis and reduced cell survival. Inhibition of prostaglandin synthesis with indomethacin not only failed to prevent hyperosmolality‐induced triglyceride synthesis but also exacerbated it. Similar results were observed with the peroxisomal proliferator activated receptor gamma (PPARγ) agonist rosiglitazone. Furthermore, hyperosmolality increased free intracellular arachidonic acid levels, which were even higher when prostaglandin synthesis was inhibited by indomethacin. Blocking PPARγ with GW‐9662 prevented the effects of both indomethacin and rosiglitazone on triglyceride synthesis and even reduced hyperosmolality‐induced triglyceride synthesis, suggesting that arachidonic acid may stimulate triglyceride synthesis through PPARγ activation. These results highlight the role of cPLA2 in osmoprotection, since it is essential to provide arachidonic acid, which is involved in PPARγ‐regulated triglyceride synthesis, thus guaranteeing cell survival. [ABSTRACT FROM AUTHOR]

The blood–retinal barrier (BRB) is strongly compromised in diabetic retinopathy (DR) due to the detachment of pericytes (PCs) from retinal microvessels, resulting in increased permeability and impairment of the BRB. Western blots, immunofluorescence and ELISA were performed on adipose mesenchymal stem cells (ASCs) and pericyte-like (P)-ASCs by co-cultured human retinal endothelial cells (HRECs) under hyperglycemic conditions (HG), as a model of DR. Our results demonstrated that: (a) platelet-derived growth factor receptor (PDGFR) and its activated form were more highly expressed in monocultured P-ASCs than in ASCs, and this expression increased when co-cultured with HRECs under high glucose conditions (HG); (b) the transcription factor Nrf2 was more expressed in the cytoplasmic fraction of ASCs and in the P-ASC nuclear fraction, under normal glucose and, even more, under HG conditions; (c) cytosolic phospholipase A2 activity and prostaglandin E2 release, stimulated by HG, were significantly reduced in P-ASCs co-cultured with HRECs; (d) HO-1 protein content was significantly higher in HG-P-ASCs/HRECs than P-ASCs/HRECs; and (e) VEGF-A levels in media from HG-co-cultures were reduced in P-ASCs/HRECs with respect to ASCs/HRECs. The data obtained highlighted the potential of autologous differentiated ASCs in future clinical applications based on cell therapy to counteract the damage induced by DR. [ABSTRACT FROM AUTHOR]

ABSTRACTGlycoprotein VI (GPVI) is the major collagen receptor on the platelet surface and is important in mediating granule secretion and atherothrombosis. Sulforaphane (SFN), a dietary isothiocyanate enriched in cruciferous vegetables, exerts multiple biological activities. This study aimed to investigate the efficacy of SFN on GPVI-mediated signaling and platelet granule secretion in vitro. We herein demonstrated that SFN greatly attenuated granule secretion in human gel-filtered platelets in response to collagen, including inhibiting CD62P and CD63 expression and PF4, CCL5, and ATP release. Mechanistically, these inhibitory effects of SFN were mainly mediated by its attenuation of cytosolic phospholipase A2 (cPLA2) phosphorylation and thromboxane A2 (TxA2) generation. Moreover, SFN did not further decrease the inhibitory effects of p38 MAPK inhibitor SB203580 on cPLA2 phosphorylation, TxA2 generation and granule secretion. Thus, SFN attenuates platelet granule secretion via down-regulating GPVI-mediated p38 MAPK/cPLA2/TxA2 signaling, which may play important preventive roles in cardiovascular diseases.

Central nervous system (CNS) trauma, including traumatic brain injury and spinal cord injury, has a high rate of disability and mortality, and effective treatment is currently lacking. Previous studies have revealed that neural inflammation plays a vital role in CNS trauma. As the initial enzyme in neuroinflammation, cytosolic phospholipase A2 (cPLA2) can hydrolyze membranous phosphatides at the sn-2 position in a preferential way to release lysophospholipids and ω3-polyunsaturated fatty acid dominated by arachidonic acid, thereby inducing secondary injuries. Although there is substantial fresh knowledge pertaining to cPLA2, in-depth comprehension of how cPLA2 participates in CNS trauma and the potential methods to ameliorate the clinical results after CNS trauma are still insufficient. The present review summarizes the latest understanding of how cPLA2 participates in CNS trauma, highlighting novel findings pertaining to how cPLA2 activation initiates the potential mechanisms specifically, neuroinflammation, lysosome membrane functions, and autophagy activity, that damage the CNS after trauma. Moreover, we focused on testing a variety of drugs capable of inhibiting cPLA2 or the upstream pathway, and we explored how those agents might be utilized as treatments to improve the results following CNS trauma. This review aimed to effectively understand the mechanism of cPLA2 activation and its role in the pathophysiological processes of CNS trauma and provide clarification and a new referential framework for future research.

Glycoprotein VI (GPVI) is the major collagen receptor on the platelet surface and is important in mediating granule secretion and atherothrombosis. Sulforaphane (SFN), a dietary isothiocyanate enriched in cruciferous vegetables, exerts multiple biological activities. This study aimed to investigate the efficacy of SFN on GPVI-mediated signaling and platelet granule secretion in vitro. We herein demonstrated that SFN greatly attenuated granule secretion in human gel-filtered platelets in response to collagen, including inhibiting CD62P and CD63 expression and PF4, CCL5, and ATP release. Mechanistically, these inhibitory effects of SFN were mainly mediated by its attenuation of cytosolic phospholipase A2 (cPLA2) phosphorylation and thromboxane A2 (TxA2) generation. Moreover, SFN did not further decrease the inhibitory effects of p38 MAPK inhibitor SB203580 on cPLA2 phosphorylation, TxA2 generation and granule secretion. Thus, SFN attenuates platelet granule secretion via down-regulating GPVI-mediated p38 MAPK/cPLA2/TxA2 signaling, which may play important preventive roles in cardiovascular diseases. [ABSTRACT FROM AUTHOR]

[Display omitted] Valproic acid (VPA) has broad efficacy against several seizures but causes liver injury limiting its prolonged clinical use. Some studies have demonstrated that VPA-induced hepatotoxicity is characterized by microvesicular hepatic steatosis. However, novel detailed mechanisms to explain VPA-induced hepatic steatosis and experimentally rigorously validated protective agents are still lacking. In this study, 8-week-old C57BL/6J mice were gavaged with VPA (500 mg/kg/d) for 4 weeks to establish an in vivo model of VPA-induced chronic liver injury. Quantitative proteomic and non-targeted lipidomic analyses were performed to explore the underlying mechanisms of VPA-induced hepatotoxicity. As a result, VPA-induced hepatotoxicity is associated with impaired autophagic flux, which is attributed to lysosomal dysfunction. Further studies revealed that VPA-induced lysosomal membrane permeabilization (LMP), allows soluble lysosomal enzymes to leak into the cytosol, which subsequently led to impaired lysosomal acidification. A lower abundance of glycerophospholipids and an increased abundance of lysophospholipids in liver tissues of mice in the VPA group strongly indicated that VPA-induced LMP may be mediated by the activation of phospholipase PLA2G4A. Metformin (Met) acted as a potential protective agent attenuating VPA-induced liver dysfunction and excessive lipid accumulation. Molecular docking and cellular thermal shift assays demonstrated that Met inhibited the activity of PLA2G4A by directly binding to it, thereby ameliorating VPA-induced LMP and autophagic flux impairment. In conclusion, this study highlights the therapeutic potential of targeting PLA2G4A-mediated lysosomal dysfunction in VPA-induced hepatotoxicity. [ABSTRACT FROM AUTHOR]

Necrosis that appears at the ischemic distal end of random-pattern skin flaps increases the pain and economic burden of patients. Necroptosis is thought to contribute to flap necrosis. Lysosomal membrane permeabilization (LMP) plays an indispensable role in the regulation of necroptosis. Nonetheless, the mechanisms by which lysosomal membranes become leaky and the relationship between necroptosis and lysosomes are still unclear in ischemic flaps. Based on Western blotting, immunofluorescence, enzyme-linked immunosorbent assay, and liquid chromatography-mass spectrometry (LC-MS) analysis results, we found that LMP was presented in the ischemic distal portion of random-pattern skin flaps, which leads to disruption of lysosomal function and macroautophagic/autophagic flux, increased necroptosis, and aggravated necrosis of the ischemic flaps. Moreover, bioinformatics analysis of the LC-MS results enabled us to focus on the role of PLA2G4E/cPLA2 (phospholipase A2, group IVE) in LMP of the ischemic flaps. In vivo inhibition of PLA2G4E with an adeno-associated virus vector attenuated LMP and necroptosis, and promoted flap survival. In addition, microRNA-seq helped us determine that Mir504-5p was differentially expressed in ischemic flaps. A string of in vitro and in vivo tests was employed to verify the inhibitory effect of Mir504-5p on PLA2G4E, LMP and necroptosis. Finally, we concluded that the inhibition of PLA2G4E by Mir504-5p reduced LMP-induced necroptosis, thereby promoting the survival of random-pattern skin flaps. Abbreviations: AAV: adeno-associated virus; ACTA2/α;-SMA: actin alpha 2, smooth muscle, aorta; ALOX15/12/15-LOX: arachidonate 15- lipoxygenase; c-CASP8: cleaved caspase; c-CASP3: cleaved caspase 3; CTSD: cathepsin D; CTSB: cathepsin B; CTSL: cathepsin L; DMECs: primary mouse dermal microvascular endothelial cells; ELISA: enzyme-linked immunosorbent assay; F-CHP: 5-FAM-conjugated collagen hybridizing peptide; FISH: fluorescence in situ hybridization; HUVECs: human umbilical vein endothelial cells; LAMP1: lysosomal-associated membrane protein 1; LAMP2: lysosomal-associated membrane protein 2; LC-MS: liquid chromatography-mass spectrometry; LDBF: laser doppler blood flow; LMP: lysosomal membrane permeabilization; LPE: lysophosphatidylethanolamine; LPC: lysophosphatidylcholine; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MLKL: mixed lineage kinase domain-like; NDI: N-dodecylimidazole; PECAM1/CD31: platelet/endothelial cell adhesion molecule 1; PLA2G4A/cPLA2: phospholipase A2, group IVA (cytosolic, calcium-dependent); PLA2G4E/cPLA2: phospholipase A2, group IVE; qPCR: quantitative real-time polymerase chain reaction; RIPK1: receptor (TNFRSF)-interacting serine-threonine kinase 1; RIPK3: receptor-interacting serine-threonine kinase 3; RISC: RNA-induced silencing complex; ROS: reactive oxygen species; shRNA: short hairpin RNA; SQSTM1: sequestosome 1; TBHP: tert-butyl hydroperoxide; TUNEL: terminal deoxynucleotidyl transferase dUTP nick end labelling. [ABSTRACT FROM AUTHOR]

Cytosolic phospholipase A2 (cPLA2) is an enzyme regulating membrane phospholipid homeostasis and the release of arachidonic acid utilized in inflammatory responses. It represents an attractive target for the treatment of Alzheimer’s disease (AD). Previously, we showed that lipopolysaccharide (LPS)-induced systemic inflammation caused abnormal lipid metabolism in the brain of a transgenic AD mouse model (APdE9), which might be associated with potential changes in cPLA2 activity. Here, we investigated changes in cPLA2 expression and activity, as well as the molecular mechanisms underlying these alterations due to chronic LPS administration in the cerebral cortex of female APdE9 mice as compared to saline- and LPS-treated female wild-type mice and saline-treated APdE9 mice. The study revealed the significant effects of genotype LPS treatment on cortical cPLA2 protein expression and activity in APdE9 mice. LPS treatment resulted in nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB) activation in the cortex of APdE9 mice. The gene expressions of inflammation markers Il1b and Tnfa were significantly elevated in the cortex of both APdE9 groups compared to the wild-type groups. The study provides evidence of the elevated expression and activity of cPLA2 in the brain cortex of APdE9 mice after chronic LPS treatment, which could be associated with NFkB activation.

Recent studies have revealed that lipid droplets accumulate in neurons after brain injury and evoke lipotoxicity, damaging the neurons. However, how lipids are metabolized by spinal cord neurons after spinal cord injury remains unclear. Herein, we investigated lipid metabolism by spinal cord neurons after spinal cord injury and identified lipid-lowering compounds to treat spinal cord injury. We found that lipid droplets accumulated in perilesional spinal cord neurons after spinal cord injury in mice. Lipid droplet accumulation could be induced by myelin debris in HT22 cells. Myelin debris degradation by phospholipase led to massive free fatty acid production, which increased lipid droplet synthesis, β-oxidation, and oxidative phosphorylation. Excessive oxidative phosphorylation increased reactive oxygen species generation, which led to increased lipid peroxidation and HT22 cell apoptosis. Bromocriptine was identified as a lipid-lowering compound that inhibited phosphorylation of cytosolic phospholipase A2 by reducing the phosphorylation of extracellular signal-regulated kinases 1/2 in the mitogen-activated protein kinase pathway, thereby inhibiting myelin debris degradation by cytosolic phospholipase A2 and alleviating lipid droplet accumulation in myelin debris-treated HT22 cells. Motor function, lipid droplet accumulation in spinal cord neurons and neuronal survival were all improved in bromocriptine-treated mice after spinal cord injury. The results suggest that bromocriptine can protect neurons from lipotoxic damage after spinal cord injury via the extracellular signal-regulated kinases 1/2-cytosolic phospholipase A2 pathway., Competing Interests: None

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the main triggers of drug hypersensitivity reactions, probably due to their high consumption worldwide. The most frequent type of NSAID hypersensitivity is NSAID cross-hypersensitivity, in which patients react to NSAIDs from different chemical groups in the absence of a specific immunological response. The underlying mechanism of NSAID cross-hypersensitivity has been linked to cyclooxygenase (COX)-1 inhibition causing an imbalance in the arachidonic acid pathway. Despite NSAID-induced acute urticaria/angioedema (NIUA) being the most frequent clinical phenotype, most studies have focused on NSAID-exacerbated respiratory disease. As NSAID cross-hypersensitivity reactions are idiosyncratic, only appearing in some subjects, it is believed that individual susceptibility is under the influence of genetic factors. Although associations with polymorphisms in genes from the AA pathway have been described, no previous study has evaluated the potential role of cytosolic phospholipase A2 (cPLA2) variants. This enzyme catalyzes the initial hydrolysis of membrane phospholipids to release AA, which can be subsequently metabolized into eicosanoids. Here, we analyzed for the first time the overall genetic variation in the cPLA2 gene (PLA2G4A) in NIUA patients. For this purpose, a set of tagging single nucleotide polymorphisms (tagSNPs) in PLA2G4A were selected using data from Europeans subjects in the 1,000 Genomes Project, and genotyped with the iPlex Sequenom MassArray technology. Two independent populations, each comprising NIUA patients and NSAID-tolerant controls, were recruited in Spain, for the purposes of discovery and replication, comprising a total of 1,128 individuals. Fifty-eight tagSNPs were successfully genotyped in the discovery cohort, of which four were significantly associated with NIUA after Bonferroni correction (rs2049963, rs2064471, rs12088010, and rs12746200). These polymorphisms were then genotyped in the replication cohort: rs2049963 was associated with increased risk for NIUA after Bonferroni correction under the dominant and additive models, whereas rs12088010 and rs12746200 were protective under these two inheritance models. Our results suggest a role for PLA2G4A polymorphisms in NIUA. However, further studies are required to replicate our findings, elucidate the mechanistic role, and evaluate the participation of PLA2G4A variants in other phenotypes induced by NSAID cross-hypersensitivity.

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Disorders of the endoplasmic reticulum (ER) lead to cellular damage but can cause cell death if ER dysfunction is prolonged. We aimed to examine liver/kidney functions, neutral sphingomyelinase (N-SMase) activity, sphingolipid levels, cytosolic phospholipase A2 (cPLA2) and cyclooxygenase-2 (COX-2) protein expression in rats under ER stress. ER stress was induced by tunicamycin (TM) and the ER stress inhibitor taurodeoxycholic acid (TUDCA) was injected before induction of ER stress. ER stress was confirmed by increased tissue levels of GRP78. Hematological and biochemical profiles were measured by autoanalyzers while hepatic and renal injury was evaluated via microscopy and histopathological scoring. Tissue levels of C16-C24 sphingomyelins (SM), C16-C24 ceramides (CERs) and sphingosine-1-phosphate (S1P) were determined by LC-MS/MS. Tissue cPLA2 and COX-2 were measured by western blot and activity assays. Tunicamycin treatment caused kidney and liver function test abnormalities, increased hematocrit and hemoglobin levels but decreased white blood cell counts. Histopathological findings showed hepatic necroinflammation and renal tubular damage in rats treated with TM. TUDCA administration attenuated WBC abnormalities and TM- induced hepatic/renal functional impairment in ER stress, as evident by significantly restored serum ALT, AST, creatinine, and total bilirubin levels. A significant increase was observed in N-SMase activity, tissue levels of C16-C24 CERs, cPLA2 and COX-2 expression in liver and kidney tissue under ER stress. TUDCA administration decreased tissue CER levels, cPLA2 and COX-2 expression as well as prostaglandin E2 (PGE2) formation. These results signify that ER stress causes hepatic and renal toxicity as well as CER-induced PGE2 formation in liver and kidney. [ABSTRACT FROM AUTHOR]

The SARS-CoV-2 virus that is the cause of coronavirus disease 2019 (COVID-19) affects not only peripheral organs such as the lungs and blood vessels, but also the central nervous system (CNS)—as seen by effects on smell, taste, seizures, stroke, neuropathological findings and possibly, loss of control of respiration resulting in silent hypoxemia. COVID-19 induces an inflammatory response and, in severe cases, a cytokine storm that can damage the CNS. Antimalarials have unique properties that distinguish them from other anti-inflammatory drugs. (A) They are very lipophilic, which enhances their ability to cross the blood-brain barrier (BBB). Hence, they have the potential to act not only in the periphery but also in the CNS, and could be a useful addition to our limited armamentarium against the SARS-CoV-2 virus. (B) They are non-selective inhibitors of phospholipase A2 isoforms, including cytosolic phospholipase A2 (cPLA2). The latter is not only activated by cytokines but itself generates arachidonic acid, which is metabolized by cyclooxygenase (COX) to pro-inflammatory eicosanoids. Free radicals are produced in this process, which can lead to oxidative damage to the CNS. There are at least 4 ways that antimalarials could be useful in combating COVID-19. (1) They inhibit PLA2. (2) They are basic molecules capable of affecting the pH of lysosomes and inhibiting the activity of lysosomal enzymes. (3) They may affect the expression and Fe2+/H+ symporter activity of iron transporters such as divalent metal transporter 1 (DMT1), hence reducing iron accumulation in tissues and iron-catalysed free radical formation. (4) They could affect viral replication. The latter may be related to their effect on inhibition of PLA2 isoforms. Inhibition of cPLA2 impairs an early step of coronavirus replication in cell culture. In addition, a secretory PLA2 (sPLA2) isoform, PLA2G2D, has been shown to be essential for the lethality of SARS-CoV in mice. It is important to take note of what ongoing clinical trials on chloroquine and hydroxychloroquine can eventually tell us about the use of antimalarials and other anti-inflammatory agents, not only for the treatment of COVID-19, but also for neurovascular disorders such as stroke and vascular dementia. [ABSTRACT FROM AUTHOR]

Background and Purpose: Autophagy is a protective factor for controlling neuronal damage, while necroptosis promotes neuroinflammation after spinal cord injury (SCI). DADLE (D-Ala 2 , D-Leu 5 ]-enkephalin) is a selective agonist for delta (δ) opioid receptor and has been identified as a promising drug for neuroprotection. The aim of this study was to investigate the mechanism/s by which DADLE causes locomotor recovery following SCI., Experimental Approach: Spinal cord contusion model was used and DADLE was given by i.p. (16 mg·kg -1 ) in mice for following experiments. Motor function was assessed by footprint and Basso mouse scale (BMS) score analysis. Western blotting used to evaluate related protein expression. Immunofluorescence showed the protein expression in each cell and its distribution. Network pharmacology analysis was used to find the related signalling pathways., Key Results: DADLE promoted functional recovery after SCI. In SCI model of mice, DADLE significantly increased autophagic flux and inhibited necroptosis. Concurrently, DADLE restored autophagic flux by decreasing lysosomal membrane permeabilization (LMP). Additionally, chloroquine administration reversed the protective effect of DADLE to inhibit necroptosis. Further analysis showed that DADLE decreased phosphorylated cPLA 2 , overexpression of cPLA 2 partially reversed DADLE inhibitory effect on LMP and necroptosis, as well as the promotion autophagy. Finally, AMPK/SIRT1/p38 pathway regulating cPLA 2 is involved in the action DADLE on SCI and naltrindole inhibited DADLE action on δ receptor and on AMPK signalling pathway., Conclusion and Implication: DADLE causes its neuroprotective effects on SCI by promoting autophagic flux and inhibiting necroptosis by decreasing LMP via activating δ receptor/AMPK/SIRT1/p38/cPLA 2 pathway., (© 2023 British Pharmacological Society.)

Physiologically, renal medullary cells are surrounded by a hyperosmolar interstitium. However, different pathological situations can induce abrupt changes in environmental osmolality, causing cell stress. Therefore, renal cells must adapt to survive in this new condition. We previously demonstrated that, among the mechanisms involved in osmoprotection, renal cells upregulate triglyceride biosynthesis (which helps preserve glycerophospholipid synthesis and membrane homeostasis) and cyclooxygenase-2 (which generates prostaglandins from arachidonic acid) to maintain lipid metabolism in renal tissue. Herein, we evaluated whether hyperosmolality modulates phospholipase A 2 (PLA 2 ) activity, leading to arachidonic acid release from membrane glycerophospholipid, and investigated its possible role in hyperosmolality-induced triglyceride synthesis and accumulation. We found that hyperosmolality induced PLA 2 expression and activity in Madin-Darby canine kidney cells. Cytosolic PLA 2 (cPLA2) inhibition, but not secreted or calcium-independent PLA 2 (sPLA 2 or iPLA 2 , respectively), prevented triglyceride synthesis and reduced cell survival. Inhibition of prostaglandin synthesis with indomethacin not only failed to prevent hyperosmolality-induced triglyceride synthesis but also exacerbated it. Similar results were observed with the peroxisomal proliferator activated receptor gamma (PPARγ) agonist rosiglitazone. Furthermore, hyperosmolality increased free intracellular arachidonic acid levels, which were even higher when prostaglandin synthesis was inhibited by indomethacin. Blocking PPARγ with GW-9662 prevented the effects of both indomethacin and rosiglitazone on triglyceride synthesis and even reduced hyperosmolality-induced triglyceride synthesis, suggesting that arachidonic acid may stimulate triglyceride synthesis through PPARγ activation. These results highlight the role of cPLA 2 in osmoprotection, since it is essential to provide arachidonic acid, which is involved in PPARγ-regulated triglyceride synthesis, thus guaranteeing cell survival., (© 2023 Federation of European Biochemical Societies.)

Calcium-sensing receptor (CaSR) is a G protein-coupled receptor (GPCRs). Soluble β-amyloid peptide (Aβ) is one of the orthosteric modulators of CaSR, while, the role and underlying mechanism of CaSR in cognitive decline in Alzheimer’s disease (AD) is unclear. In this study, molecular technology such as live-cell imaging combined with behavioral tests were used to explore the role and the underlying mechanism of CaSR in the cognitive deficits in AD mice. The expression levels of CaSR were increased both in AD mice and Aβ1–42 (β-amyloid protein)-treated primary cultured neurons. Pharmacological inhibition of CaSR ameliorated recognitive and spatial memory deficits of Aβ1–42-oligomer-treated mice in a dose-dependent manner. Pharmacological inhibition of CaSR or down-regulation of the expression of CaSR by CaSR-shRNA-lentivirus prevented the impairment of filopodia, and the synapse induced by oligomeric Aβ1–42. The contents of cytosolic phospholipase A2 (cPLA2) and prostaglandin E2 (PGE2) in hippocampal neurons and tissue were increased after treatment with Aβ1–42 oligomers. Inhibition or down-regulation of CaSR mediates Aβ-induced synapse formation and cognitive deficits partially, through the activation of the cPLA2/PGE2 pathway. This study provides novel insights on CaSR, which is a promising therapeutic target for AD.

Singapore grouper iridovirus (SGIV), belonging to genus Ranavirus, family Iridoviridae, causes great economic losses in the aquaculture industry. Previous studies demonstrated the lipid composition of intracellular unenveloped viruses, but the changes in host-cell glyceophospholipids components and the roles of key enzymes during SGIV infection still remain largely unknown. Here, the whole cell lipidomic profiling during SGIV infection was analyzed using UPLC-Q-TOF-MS/MS. The lipidomic data showed that glycerophospholipids (GPs), including phosphatidylcholine (PC), phosphatidylserine (PS), glycerophosphoinositols (PI) and fatty acids (FAs) were significantly elevated in SGIV-infected cells, indicating that SGIV infection disturbed GPs homeostasis, and then affected the metabolism of FAs, especially arachidonic acid (AA). The roles of key enzymes, such as cytosolic phospholipase A2 (cPLA2), 5-Lipoxygenase (5-LOX), and cyclooxygenase (COX) in SGIV infection were further investigated using the corresponding specific inhibitors. The inhibition of cPLA2 by AACOCF3 decreased SGIV replication, suggesting that cPLA2 might play important roles in the process of SGIV infection. Consistent with this result, the ectopic expression of EccPLA2α or knockdown significantly enhanced or suppressed viral replication in vitro, respectively. In addition, the inhibition of both 5-LOX and COX significantly suppressed SGIV replication, indicating that AA metabolism was essential for SGIV infection. Taken together, our results demonstrated for the first time that SGIV infection in vitro disturbed GPs homeostasis and cPLA2 exerted crucial roles in SGIV replication.

Calcium-sensing receptor (CaSR) is a G protein-coupled receptor (GPCRs). Soluble β-amyloid peptide (Aβ) is one of the orthosteric modulators of CaSR, while, the role and underlying mechanism of CaSR in cognitive decline in Alzheimer's disease (AD) is unclear. In this study, molecular technology such as live-cell imaging combined with behavioral tests were used to explore the role and the underlying mechanism of CaSR in the cognitive deficits in AD mice. The expression levels of CaSR were increased both in AD mice and Aβ1–42 (β-amyloid protein)-treated primary cultured neurons. Pharmacological inhibition of CaSR ameliorated recognitive and spatial memory deficits of Aβ1–42-oligomer-treated mice in a dose-dependent manner. Pharmacological inhibition of CaSR or down-regulation of the expression of CaSR by CaSR-shRNA-lentivirus prevented the impairment of filopodia, and the synapse induced by oligomeric Aβ1–42. The contents of cytosolic phospholipase A2 (cPLA2) and prostaglandin E2 (PGE2) in hippocampal neurons and tissue were increased after treatment with Aβ1–42 oligomers. Inhibition or down-regulation of CaSR mediates Aβ-induced synapse formation and cognitive deficits partially, through the activation of the cPLA2/PGE2 pathway. This study provides novel insights on CaSR, which is a promising therapeutic target for AD. [ABSTRACT FROM AUTHOR]

Abstract Background Autism is neurodevelopmental disorder that is characterized by developmental, behavioral, social and sensory abnormalities. Researchers have focused in last years in immunological alteration and inflammation as a hot subject in autism field. This work aims to study the alteration in phospholipids (PE, PS, and PC) together with the change in cPLA2 concentration as the main phospholipid hydrolytic enzyme in autistic patients compared to control. It was also extended to find a correlation between these biomarkers and severity of autism measured as childhood autism rating scale (CARS), Social responsiveness scale (SRS), and Short sensory profile (SSP). Methods Phospholipids (PE, PS, PC) and cPLA2 as biochemical parameters were determined in the plasma of 48 Saudi autistic male patients, categorized as mild-moderate and severe as indicated by their Childhood Autism Rating Scale (CARS), social responsiveness scale (SRS) and short sensory profile (SSP) and compared to 40 age- and gender-matched control samples. Results The reported data demonstrate significantly lower levels of PE, PS, and PC together with a significant increase in cPLA2. While association between severity of autism and impaired phospholipid concentration was completely lacked, an association between cPLA2 and impaired sensory processing was observed. Conclusions The impaired phospholipid level and remarkable increased in cPLA2 concentration asserted their roles in the etiology of autism. Receiver operating characteristic analysis together with predictiveness diagrams proved that the measured parameters could be used as predictive biomarkers of clinical symptoms and provide significant guidance for future therapeutic strategy to re-establish physiological homeostasis.

Background: Alzheimer's disease (AD) is a neurodegenerative disorder lacking any curative treatment up to now. Indeed, actual medication given to the patients alleviates only symptoms. The cytosolic phospholipase A2 (cPLA 2 -IVA) appears as a pivotal player situated at the center of pathological pathways leading to AD and its inhibition could be a promising therapeutic approach., Objective: A cPLA 2 -IVA inhibiting peptide was identified in the present work, aiming to develop an original therapeutic strategy., Methods: We targeted the cPLA 2 -IVA using the phage display technology. The hit peptide PLP25 was first validated in vitro (arachidonic acid dosage [AA], cPLA 2 -IVA cellular translocation) before being tested in vivo . We evaluated spatial memory using the Barnes maze, amyloid deposits by MRI and immunohistochemistry (IHC), and other important biomarkers such as the cPLA 2 -IVA itself, the NMDA receptor, AβPP and tau by IHC after i.v. injection in APP/PS1 mice., Results: Showing a high affinity for the C2 domain of this enzyme, the peptide PLP25 exhibited an inhibitory effect on cPLA 2 -IVA activity by blocking its binding to its substrate, resulting in a decreased release of AA. Coupled to a vector peptide (LRPep2) in order to optimize brain access, we showed an improvement of cognitive abilities of APP/PS1 mice, which also exhibited a decreased number of amyloid plaques, a restored expression of cPLA 2 -IVA, and a favorable effect on NMDA receptor expression and tau protein phosphorylation., Conclusions: cPLA 2 -IVA inhibition through PLP25 peptide could be a promising therapeutic strategy for AD., Competing Interests: The authors have no conflict of interest to report., (© 2023 – The authors. Published by IOS Press.)

Kaempferol, a phytochemical found in many edible plants, is known to alleviate diseases such as cancer, allergy, and inflammation. The objective of this study was to investigate whether kaempferol could reduce omega-6 and ovalbumin-mediated allergic reactions at lung and trachea in BALB/c mice. Mice were allocated into five groups: 1) control group (CON); 2) positive control group with orally administration of omega-6 (POS); 3) bovine serum albumin (BSA) sensitization group (with BSA injection and ovalbumin inhalation); 4) BSA+K10 group: BSA injection, 10 μg/g of kaempferol administration and ovalbumin inhalation; and 5) BSA+K20 group: BSA injection, 20 μg/g of kaempferol administration and ovalbumin inhalation. Results revealed that serum histamine level was the highest (p

Cytosolic phospholipase A2 (cPLA2) mediates oligomeric amyloid-β peptide (oAβ)-induced oxidative and inflammatory responses in glial cells. Increased activity of cPLA2 has been implicated in the neuropathology of Alzheimer's disease (AD), suggesting that cPLA2 regulation of oAβ-induced microglial activation may play a role in the AD pathology. We demonstrate that LPS, IFNγ, and oAβ increased phosphorylated cPLA2 (p-cPLA2) in immortalized mouse microglia (BV2). Aβ association with primary rat microglia and BV2 cells, possibly via membrane-binding and/or intracellular deposition, presumably indicative of microglia-mediated clearance of the peptide, was reduced by inhibition of cPLA2. However, cPLA2 inhibition did not affect the depletion of this associated Aβ when cells were washed and incubated in a fresh medium after oAβ treatment. Since the depletion was abrogated by NH4Cl, a lysosomal inhibitor, these results suggested that cPLA2 was not involved in the degradation of the associated Aβ. To further dissect the effects of cPLA2 on microglia cell membranes, atomic force microscopy (AFM) was used to determine endocytic activity. The force for membrane tether formation (Fmtf) is a measure of membrane-cytoskeleton connectivity and represents a mechanical barrier to endocytic vesicle formation. Inhibition of cPLA2 increased Fmtf in both unstimulated BV2 cells and cells stimulated with LPS + IFNγ. Thus, increasing p-cPLA2 would decrease Fmtf, thereby increasing endocytosis. These results suggest a role of cPLA2 activation in facilitating oAβ endocytosis by microglial cells through regulation of the membrane-cytoskeleton connectivity. [ABSTRACT FROM AUTHOR]

Highlights • The plasma concentration of iPLA2 was increased in schizophrenia while cPLA2 not. • Meta-analysis showed the iPLA2 in schizophrenia was increased while cPLA2 was not. • The correlation between the iPLA2 and skin flushing response was positive. Abstract Evidence indicates that abnormal phospholipase A2 (PLA2) levels and niacin insensitivity are present in individuals with schizophrenia. This study was designed to determine whether differences in plasma calcium-independent phospholipase A2 (iPLA2) and cytosolic phospholipase A2 (cPLA2) exist between those with schizophrenia and healthy controls, and to explore the correlation between PLA2s and the niacin skin reaction in schizophrenic patients. We performed ELISA experiments to measure the concentrations of plasma iPLA2 and cPLA2 and we conducted a series of niacin skin tests on schizophrenic patients from the Chinese Han population. In addition, a meta-analysis of the relationship between PLA2 and schizophrenia was conducted. The plasma concentration of iPLA2 in patients with schizophrenia was significantly higher than that in healthy controls while the plasma concentration of cPLA2 did not differ. The meta-analysis also revealed that the activity level of iPLA2 in individuals with schizophrenia was higher than that in healthy controls, whereas that of cPLA2 was not. Furthermore, a significant positive correlation was found between the concentration of iPLA2 and the score for the skin flushing response within 20 min. The abnormal plasma iPLA2 concentration and its relationship with the niacin skin test in schizophrenic patients has contributed to a deeper understanding of the pathology of schizophrenia, which may in turn provide new insights into the clinical diagnoses and treatment of schizophrenia. [ABSTRACT FROM AUTHOR]

White matter degeneration is a pathological hallmark of neurodegenerative diseases including Alzheimer's. Age remains the greatest risk factor for Alzheimer's and the prevalence of age-related late onset Alzheimer's is greatest in females. We investigated mechanisms underlying white matter degeneration in an animal model consistent with the sex at greatest Alzheimer's risk. Results of these analyses demonstrated decline in mitochondrial respiration, increased mitochondrial hydrogen peroxide production and cytosolic-phospholipase-A2 sphingomyelinase pathway activation during female brain aging. Electron microscopic and lipidomic analyses confirmed myelin degeneration. An increase in fatty acids and mitochondrial fatty acid metabolism machinery was coincident with a rise in brain ketone bodies and decline in plasma ketone bodies. This mechanistic pathway and its chronologically phased activation, links mitochondrial dysfunction early in aging with later age development of white matter degeneration. The catabolism of myelin lipids to generate ketone bodies can be viewed as a systems level adaptive response to address brain fuel and energy demand. Elucidation of the initiating factors and the mechanistic pathway leading to white matter catabolism in the aging female brain provides potential therapeutic targets to prevent and treat demyelinating diseases such as Alzheimer's and multiple sclerosis. Targeting stages of disease and associated mechanisms will be critical.

Objective: To investigate the mechanism of cytosolic phospholipase A2(cPLA2) inhibitor to improve neurological function after spinal cord injury (SCI)., Methods: Thirty-six 3 months old female SD rats, with body mass (280±20) g, were divided into three groups ( n =12):sham group, SCI group, and SCI+ arachidonyl trifluoromethyl ketone(AACOCF3) group. Balloon compression SCI model was established in all three groups. In the sham model group, the spinal cord compression model was created after the balloon was placed without pressure treatment, and the remaining two groups were pressurized with the balloon for 48 h. After successful modeling, rats in the SCI+AACOCF3 group were injected intraperitoneally with AACOCF3, a specific inhibitor of cPLA2. The remaining two groups of rats were injected intraperitoneally with saline. The animals were sacrificed in batches on 7 and 14 days after modeling, respectively. And the damaged spinal cord tissues were sampled for pathomorphological observation, to detect the expression of cPLA2 and various autophagic fluxPrelated molecules and test the recovery of motor function., Results: Spinal cord histomorphometry examination showed that the spinal cord tissue in the sham group was structurally intact, with normal numbers and morphology of neurons and glial cells. In the SCI group, spinal cord tissue fractures with large and prominent spinal cord cavities were seen. In the SCI+AACOCF3 group, the spinal cord tissue was more intact than in the SCI group, with more fused spinal cord cavities, more surviving neurons, and less glial cell hyperplasia. Western blot showed that the sham group had the lowest protein expression of LC3-Ⅱ, Beclin 1, p62, and cPLA2 compared with the SCI and SCI+AACOCF3 groups ( P <0.05) and the highest protein expression of LC3-Ⅰ ( P <0.05). P62 and cPLA2 expression in the SCI group were higher than in the SCI+AACOCF3 group ( P <0.05). Behavioral observations showed that the time corresponding to BBB exercise scores was significantly lower in both the SCI and SCI+AACOCF3 groups than in the sham group ( P <0.05). Scores at 3, 7, and 14 days after pressurization were higher in the SCI+AACOCF3 group than in the SCI group ( P <0.05)., Conclusion: cPLA2 inhibitors can reduce neuronal damage secondary to SCI, promote neurological recovery and improve motor function by improving lysosomal membrane permeability and regulating autophagic flux.

Objective: To observe the effect of electroacupuncture（EA） on the expression of cytosolic phospholipase A2 （cPLA2） and apoptosis of nerve cells in rats with spinal cord injury （SCI）, so as to explore its mechanisms underlying improvement of SCI., Methods: Seventy-two female SD rats were randomly divided into model, EA, antagonist and EA+antagonist groups, with 18 rats in each group and other 18 rats were used as the sham operation （sham） group. The SCI model was established by referring to modified Allen's method with a weight impactor. The hindlimb motor function was assessed by using Basso-Beattie-Bresnahan （BBB） score. Rats of the EA group were subjected to EA stimulation at "Dazhui"（GV14）, "Yaoyangguan"（GV3）, bilateral "Ciliao"（BL32） and "Zusanli"（ST36） for 20 min, once a day for 14 days. Rats of the antagonist group received intravenous injection followed by intraperitoneal injection of arachidonyl trifluoromethyl ketone （AACOCF3, antagonist of cPLA2）, once every other day. Rats of the EA+antagonist group received EA treatment combined with antagonist injection. After the treatment, the rats were sacrificed and the spinal cord tissue was collected for detecting the protein expression of cPLA2, p-cPLA2, Bcl-2, Bax and Caspase-3 by Western blot, and the mRNA expression of cPLA2, Bcl-2, Bax and Caspase-3 using qRT-PCR. The morphological changes of the spinal cord were detected by Nissl staining., Results: In comparison with the sham group, the BBB score, expression of Bcl-2 protein and mRNA were significantly down-regulated （ P <0.01）, whereas the expression levels of Bax, Caspase-3 and p-cPLA2 proteins and mRNAs were considerably up-regulated in the model group （ P <0.01）. Compared with the model group, the BBB score, expression levels of Bcl-2 protein and mRNA were significantly up-regulated （ P <0.01, P <0.05）, while the expression levels of Bax, Caspase-3 and p-cPLA2 proteins in the EA, antagonist and EA+antagonist groups, Bax and cPLA2 mRNAs in both antagonist and EA+antagonist groups, and Caspase-3 mRNA in the EA+antagonist group were obviously down-regulated （ P <0.01, P <0.05）. The effect of EA+antagonist was significantly superior to EA in increasing BBB score and in lowering expression of Bax and cPLA2 mRNAs （ P <0.01, P <0.05）. Nissl staining showed reduced number of nerve cells and Nissl bodies, and striped dark blue cells in the model group, which was milder in the EA and antagonist groups, particularly in the EA+antagonist group., Conclusion: EA may improve the limb motor function of SCI rats, which may be related to its functions in down-regulating the expression of p-cPLA2, Bax and Caspase-3 and up-regulating Bcl-2 to reduce the apoptosis of nerve cells in the regional spinal cord.

The aim of the present study was to investigate the potential role of club cell secretory protein (CCSP), an endogenous modulator, in reducing pulmonary inflammation induced by sevoflurane following one-lung ventilation (OLV). Healthy Japanese white rabbits were randomly assigned to six groups: Sham-operated group (group S); respiratory management of OLV group (group O); OLV + sevoflurane treated group (group OF), club cells exfoliated + sham-operated group (group NA), club cells exfoliated + OLV group (group NAO); and club cells exfoliated + OLV + sevoflurane treated group (group NAOF). At the end of the experimental observation, all animals in the different groups were sacrificed and lung injury was evaluated according to the lung wet/dry weight ratio and histological scoring system. Lung homogenates were harvested to detect the mRNA and protein expression of cytosolic phospholipase A2 (c-PLA2) and CCSP. The content of arachidonic acid was measured using an ELISA. Following OLV treatment, c-PLA2 expression was increased, CCSP expression was decreased and lung injury scores were significantly increased. Sevoflurane inhalation in the OLV-treated group induced an upregulation of CCSP and a downregulation of c-PLA2 expression. In the group NAO, in which the club cells were simultaneously exfoliated, OLV caused more severe lung damage and induced higher expression of c-PLA2 compared with that in group O. However, sevoflurane inhalation reduced the extent of lung injury and the expression of c-PLA2, even when the endogenous modulator of lung inflammation, CCSP, was exfoliated (group NAOF). These results indicated that OLV promoted lung inflammation through the CCSP and c-PLA2 pathway. However, the results from the club cells exfoliated group indicated that the CCSP may not be involved in the protective effect exerted by sevoflurane inhalation. [ABSTRACT FROM AUTHOR]

During radiotherapy, an inflammatory response might be induced by activating various enzymes involved in membrane lipid metabolism. The eicosanoid pathway associated with cytosolic phospholipase A2 (cPLA2), cyclooxygenases (COXs), and lipoxygenases (LOXs) can be induced by radiation, and many lipid metabolites might contribute to cancer-associated inflammation, cell proliferation, and cell survival in cancer. The lipid metabolites are also involved in the establishment of the tumor-associated microenvironment through promotion of angiogenesis and formation of vascular network. These biological activities of lipid metabolites are responsible for malignant progression with the acquisition of radioresistance, leading to unsatisfactory outcome of cancer radiotherapy. Many efforts have been made to identify the mechanisms associated with bioactive lipid metabolites and radiation signaling that lead to radioresistance and to develop potent radiosensitizers to improve therapeutic efficacy. Beneficial outcomes would be achieved by targeting the enzymes, such as cPLA2, COXs, and LOXs, responsible for arachidonic acid metabolism and cancer-associated inflammation during cancer radiotherapy. The current study demonstrated a brief review for the radioresistant effects of bioactive lipid metabolites and their enzymes in cancer and the radiosensitizing effects of inhibitors for the enzymes on cancer therapy. [ABSTRACT FROM AUTHOR]

Taxifolin is a potent flavonoid with anti-inflammatory activity. Taxifolin has been reported to decrease the accumulation of β-amyloid (Aβ), and reduce Aβ-induced neurotoxicity. However, the detail molecular mechanism of taxifolin against Aβ-induced neurotoxicity is largely unknown. In this study, we revealed the protective effects and the underlying mechanisms of taxifolin on the impairments of cognitive function and synapse formation induced by soluble Aβ oligomers. Our results showed that taxifolin prevented neuronal cell death in a concentration-dependent manner. The recognition memory in novel object recognition tasks and the spatial memory in Morris water maze tests are significantly lower in the Alzheimer’s disease (AD) model mice induced by hippocampal injection of Aβ42. Taxifolin treatment prevented the recognitive and spatial memory deficits of the AD mice. 10 mg/kg taxifolin treatment also significantly prevented the decreased expression levels of PSD 95 induced by Aβ42. Live cell imaging study showed that 2 h pre-treatment of taxifolin prevented the decrease in the number of filopodium and spine induced by Aβ42 oligomers. Aβ42 oligomers significantly increased the production of cytosolic phospholipase A2 (cPLA2), a crucial enzyme of pro-inflammatory mediator, and prostaglandin E2 (PGE2), a neuroinflammatory molecule. Taxifolin significantly reduced the content of cPLA2 and PGE2 induced by Aβ42 both in the primary hippocampal neurons and hippocampal tissues. These results indicated that taxifolin might prevent Aβ42 oligomer-induced synapse and cognitive impairments through decreasing cPLA2 and PGE2. Our study provided novel insights into the cellular mechanisms for the protective effects of taxifolin on AD. [ABSTRACT FROM AUTHOR]

Abstract: The metabolism of polyunsaturated fatty acids (PUFAs) remains poorly characterized in ovarian tissues of patients with polycystic ovary syndrome (PCOS). This study aimed to explore alterations in the levels of PUFAs and their metabolites in serum and ovarian tissues in a PCOS rat model treated with a high‐fat diet and andronate. Levels of PUFAs and their metabolites were measured using gas/liquid chromatography‐mass spectrometry after the establishment of a PCOS rat model. Only 3 kinds of PUFAs [linoleic acid, arachidonic acid (AA) and docosahexaenoic acid] were detected in both the circulation and ovarian tissues of the rats, and their concentrations were lower in ovarian tissues than in serum. Moreover, significant differences in the ovarian levels of AA were observed between control, high‐fat diet‐fed and PCOS rats. The levels of prostaglandins, AA metabolites via the cyclooxygenase (COX) pathway, in ovarian tissues of the PCOS group were significantly increased compared to those in the controls. Further studies on the mechanism underlying this phenomenon showed a correlation between decreased expression of phosphorylated cytosolic phospholipase A2 (p‐cPLA2) and increased mRNA and protein expression of COX2, potentially leading to a deeper understanding of altered AA and prostaglandin levels in ovarian tissues of PCOS rats. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) is the second most commonly diagnosed cancer in females and the third in males. In this work, we aim to investigate the possible anti-cancer effects of interferon-gamma (IFN-γ) in CRC cells. We observed that IFN-γ induced mitochondria-derived reactive oxygen species (ROS) production in a time-dependent manner in SW480 and HCT116 cell lines. The IFN-γ-induced mitochondrial ROS generation was dependent on the activation of cytosolic phospholipase A2 (cPLA2). In addition, a mitochondria-targeted antioxidant SS31 and/or cPLA2 inhibitor AACOCF3 abolished the IFN-γ-induced ROS production and subsequent autophagy and apoptosis. Moreover, suppression of autophagy by CQ was able to reduce IFN-γ-induced cell apoptosis. Beclin-1 gene silencing resulted in caspase-3 inactivation, decreased Bax/Bcl-2 ratio and less population of apoptotic cells. Collectively, our results suggested that IFN-γ induces autophagy-associated apoptosis in CRC cells via inducing cPLA2-dependent mitochondrial ROS production. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor-alpha (TNF-alpha) triggers activation of cytosolic phospholipase A2 (cPLA2) and then enhancing the synthesis of prostaglandin (PG) in inflammatory diseases. However, the detailed mechanisms of TNF-alpha induced cPLA2 expression were not fully defined in human pulmonary alveolar epithelial cells (HPAEpiCs). We found that TNF-alpha-stimulated increases in cPLA2 mRNA (5.2 folds) and protein (3.9 folds) expression, promoter activity (4.3 folds), and PGE2 secretion (4.7 folds) in HPAEpiCs, determined by Western blot, real-time PCR, promoter activity assay and PGE2 ELISA kit. These TNF-alpha-mediated responses were abrogated by the inhibitors of NADPH oxidase [apocynin (APO) and diphenyleneiodonium chloride (DPI)], ROS [N-acetyl cysteine, (NAC)], NF-kappaB (Bay11-7082) and transfection with siRNA of ASK1, p47phox, TRAF2, NIK, IKKalpha, IKKbeta, or p65. TNF-alpha markedly stimulated NADPH oxidase activation and ROS including superoxide and hydrogen peroxide production which were inhibited by pretreatment with a TNFR1 neutralizing antibody, APO, DPI or transfection with siRNA of TRAF2, ASK1, or p47phox. In addition, TNF-alpha also stimulated p47phox phosphorylation and translocation in a time-dependent manner. On the other hand, TNF-alpha induced TNFR1, TRAF2, ASK1, and p47phox complex formation in HPAEpiCs, which were attenuated by a TNF-alpha neutralizing antibody. We found that pretreatment with NAC, DPI, or APO also attenuated the TNF-alpha-stimulated IKKalpha/beta and NF-kappaB p65 phosphorylation, NF-kappaB (p65) translocation, and NF-kappaB promoter activity in HPAEpiCs. Finally, we observed that TNF-alpha-stimulated NADPH oxidase activation and ROS generation activates NF-kappaB through the NIK/IKKalpha/beta pathway. Taken together, our results demonstrated that in HPAEpiCs, up-regulation of cPLA2 by TNF-alpha is, at least in part, mediated through the cooperation of TNFR1, TRAF2, ASK1, and NADPH oxidase leading to ROS generation and ultimately activates NF-kappaB pathway.

Cytosolic phospholipase A2α (cPLA2α) is a key enzyme in regulation of inflammation process and neuromembrane homeostasis, both of which are critical in pathogenesis of Alzheimer’s diseases. By hybride APP/PS1 Tg-AD mice with cPLA2α knockout mice, three lines of APP/PS1 Tg-AD mice were produced with genotypes of cPLA2α +/+ , cPLA2α +/− and cPLA2α −/− . Compared to cPLA2α +/+ Tg-AD mice, the amyloid plaque formation was significantly downregulated in the brain of cPLA2α +/− Tg-AD mice, but not in cPLA2α −/− Tg-AD mice. The reactive gliosis were also significantly downregulated in both cPLA2α +/− and cPLA2α −/− Tg-AD mouse lines. The paradoxical effects of cPLA2α on the amyloid plaques reveal a complex role of cPLA2α in pathogenesis of AD and could be a potential target for prevention and treatment of AD. [ABSTRACT FROM AUTHOR]

Background: Polyunsaturated fatty acids play a crucial role in neuronal function, and the modification of these compounds in the brain could have an impact on neurodegenerative diseases such as Alzheimer's disease. Despite the fact that arachidonic acid is the second foremost polyunsaturated fatty acid besides docosahexaenoic acid, its role and the regulation of its transfer and mobilization in the brain are poorly known. Methods: Two groups of 39 adult male BALB/c mice were fed with an arachidonic acid-enriched diet or an oleic acid-enriched diet, respectively, for 12 weeks. After 10 weeks on the diet, mice received intracerebroventricular injections of either NaCl solution or amyloid-β peptide (Aβ) oligomers. Y-maze and Morris water maze tests were used to evaluate short- and long-term memory. At 12 weeks on the diet, mice were killed, and blood, liver, and brain samples were collected for lipid and protein analyses. Results: We found that the administration of an arachidonic acid-enriched diet for 12 weeks induced short-term memory impairment and increased deleterious effects of Aβ oligomers on learning abilities. These cognitive alterations were associated with modifications of expression of a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, postsynaptic density protein 95, and glial fibrillary acidic protein in mouse cortex or hippocampus by the arachidonic acid-enriched diet and Aβ oligomer administration. This diet also led to an imbalance between the main ω-6 fatty acids and the ω-3 fatty acids in favor of the first one in erythrocytes and the liver as well as in the hippocampal and cortical brain structures. In the cortex, the dietary arachidonic acid also induced an increase of arachidonic acid-containing phospholipid species in phosphatidylserine class, whereas intracerebroventricular injections modified several arachidonic acid- and docosahexaenoic acid-containing species in the four phospholipid classes. Finally, we observed that dietary arachidonic acid decreased the expression of the neuronal form of acyl-coenzyme A synthetase 4 in the hippocampus and increased the cytosolic phospholipase A2 activation level in the cortices of the mice. Conclusions: Dietary arachidonic acid could amplify Aβ oligomer neurotoxicity. Its consumption could constitute a risk factor for Alzheimer's disease in humans and should be taken into account in future preventive strategies. Its deleterious effect on cognitive capacity could be linked to the balance between arachidonic acid-mobilizing enzymes. [ABSTRACT FROM AUTHOR]

Background: Autism is neurodevelopmental disorder that is characterized by developmental, behavioral, social and sensory abnormalities. Researchers have focused in last years in immunological alteration and inflammation as a hot subject in autism field. This work aims to study the alteration in phospholipids (PE, PS, and PC) together with the change in cPLA2 concentration as the main phospholipid hydrolytic enzyme in autistic patients compared to control. It was also extended to find a correlation between these biomarkers and severity of autism measured as childhood autism rating scale (CARS), Social responsiveness scale (SRS), and Short sensory profile (SSP). Methods: Phospholipids (PE, PS, PC) and cPLA2 as biochemical parameters were determined in the plasma of 48 Saudi autistic male patients, categorized as mild-moderate and severe as indicated by their Childhood Autism Rating Scale (CARS), social responsiveness scale (SRS) and short sensory profile (SSP) and compared to 40 age- and gender-matched control samples. Results: The reported data demonstrate significantly lower levels of PE, PS, and PC together with a significant increase in cPLA2. While association between severity of autism and impaired phospholipid concentration was completely lacked, an association between cPLA2 and impaired sensory processing was observed. Conclusions: The impaired phospholipid level and remarkable increased in cPLA2 concentration asserted their roles in the etiology of autism. Receiver operating characteristic analysis together with predictiveness diagrams proved that the measured parameters could be used as predictive biomarkers of clinical symptoms and provide significant guidance for future therapeutic strategy to re-establish physiological homeostasis. [ABSTRACT FROM AUTHOR]

• FFD reduced macrophage and neutrophil infiltration in lung tissue. • FFD inhibited the production of cytokines and chemokines. • FFD reduced downstream hydrolysis of cPLA2 arachidonic acid and leukotriene B4. • FFD inhibited LPS-induced cPLA2/ERK/P65 signaling pathway by targeting cPLA2. Acute lung injury (ALI) causes acute respiratory distress syndrome, with a high mortality rate of 40%, with currently available pharmacological treatments. Cytosolic phospholipase A2 (cPLA2) plays a critical role in the lipopolysaccharide (LPS)-induced pathology of ALI. This study assessed the therapeutic effects of fexofenadine (FFD), an on-market small-molecule drug that can target cPLA2 in LPS-induced ALI. Primary macrophages obtained from the bone marrow of wild-type and cPLA2 knockout mice and the alveolar macrophage cell line, MHS were used to test the inhibitory effect of FFD on the cPLA2/ERK/p65 signaling pathway, NF-κB p65 translocation, and cytokine and chemokine production. An LPS-induced ALI mouse model was used to assess the treatment effects of FFD. Flow cytometry detected subsets of macrophages and neutrophils. cPLA2 activity and downstream hydrolysates were detected. Treatment with a cPLA2 inhibitor or NF-κB p65 inhibitor confirmed that FFD functioned through the cPLA2/ERK/p65 signaling pathway by targeting cPLA2. FFD reduced the infiltration of macrophages and neutrophils, decreased the protein secretion in bronchoalveolar lavage fluid, and reduced the production of TNFα, IL-1β, IL-6, MCP-1, and IL-8 in the lung, bronchoalveolar lavage fluid, and sera of LPS-induced ALI mice. FFD inhibited cPLA2 activity, suppressed the cPLA2/ERK/p65 signaling pathway, inhibited translocation of p65, and decreased the production of cytokines, chemokines, and downstream hydrolysates of cPLA2, arachidonic acid, and leukotriene B4. FFD inhibits the cPLA2/ERK/p65 signaling pathway by targeting cPLA2. Therefore, FFD is promising as a therapeutic against cPLA2-involved diseases, particularly ALI. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor-α (TNF-α) triggers activation of cytosolic phospholipase A2 (cPLA2) and then enhancing the synthesis of prostaglandin (PG) in inflammatory diseases. However, the detailed mechanisms of TNF-α induced cPLA2 expression were not fully defined in human pulmonary alveolar epithelial cells (HPAEpiCs). We found that TNF-α-stimulated increases in cPLA2 mRNA (5.2 folds) and protein (3.9 folds) expression, promoter activity (4.3 folds), and PGE2 secretion (4.7 folds) in HPAEpiCs, determined by Western blot, real-time PCR, promoter activity assay and PGE2 ELISA kit. These TNF-a-mediated responses were abrogated by the inhibitors of NADPH oxidase [apocynin (APO) and diphenyleneiodonium chloride (DPI)], ROS [Nacetyl cysteine, (NAC)], NF-κB (Bay11-7082) and transfection with siRNA of ASK1, p47phox, TRAF2, NIK, IKKa, IKKb, or p65. TNF-a markedly stimulated NADPH oxidase activation and ROS including superoxide and hydrogen peroxide production which were inhibited by pretreatment with a TNFR1 neutralizing antibody, APO, DPI or transfection with siRNA of TRAF2, ASK1, or p47phox. In addition, TNF-α also stimulated p47phox phosphorylation and translocation in a time-dependent manner. On the other hand, TNF-α induced TNFR1, TRAF2, ASK1, and p47phox complex formation in HPAEpiCs, which were attenuated by a TNF-α neutralizing antibody. We found that pretreatment with NAC, DPI, or APO also attenuated the TNF-a-stimulated IKKa/b and NF-κB p65 phosphorylation, NF-κB (p65) translocation, and NF-κB promoter activity in HPAEpiCs. Finally, we observed that TNF-a-stimulated NADPH oxidase activation and ROS generation activates NF-κB through the NIK/IKKa/b pathway. Taken together, our results demonstrated that in HPAEpiCs, up-regulation of cPLA2 by TNF-α is, at least in part, mediated through the cooperation of TNFR1, TRAF2, ASK1, and NADPH oxidase leading to ROS generation and ultimately activates NF-κB pathway. [ABSTRACT FROM AUTHOR]

Background: Cytosolic phospholipase A2 (cPLA2) plays a key role in the development of late-phase anaphylaxis. L -Glutamine (Gln), a nonessential amino acid, has anti-inflammatory activity via inhibiting cPLA2. Methods: We used a penicillininduced murine model of anaphylaxis, and late-phase anaphylaxis was quantified by measuring the increase in the hematocrit (Ht) value. Various inhibitors, small interfering RNA, and knockout mice were used in inhibition experiments. Phosphorylation and protein expression of cPLA2, ERK, and MAPK phosphatase 1 (MKP-1) were detected by Western blotting. Results: Leukotriene (LT) B4 was found to be another potent inducer of late-phase anaphylaxis besides the known mediator platelet-activating-factor (PAF). Gln efficiently prevented late-phase anaphylaxis when it was administered up to 3 h after challenge injection via inhibiting cPLA2. Inhibition studies indicated that p38 MAPK was the major upstream regulator of cPLA2. Gln dephosphorylated p38 and cPLA2 via up-regulating the negative regulator of p38 MAPK, i.e., MKP-1 protein. MKP-1 blockade abrogated all the effects of Gln. Conclusion: Of the cPLA2 metabolites, PAF and LTB4 play a key role in the development of late-phase anaphylaxis, and Gln prevents the reaction via MKP-1-dependent deactivation of cPLA2. [ABSTRACT FROM AUTHOR]

Multiple reports have demonstrated a role for ceramide kinase (CERK) in the production of eicosanoids. To examine the effects of the genetic ablation of CERK on eicosanoid synthesis, primary mouse embryonic fibroblasts (MEFs) and macrophages were isolated from CERK−/− and CERK+/+ mice, and the ceramide-1-phosphate (C1P) and eicosanoid profiles were investigated. Significant decreases were observed in multiple C1P subspecies in CERK−/− cells as compared to CERK+/+ cells with overall 24% and 48% decreases in total C1P. In baseline experiments, the levels of multiple eicosanoids were significantly lower in the CERK−/− cells compared with wild-type cells. Importantly, induction of eicosanoid synthesis by calcium ionophore was significantly reduced in the CERK−/− MEFs. Our studies also demonstrate that the CERK−/− mouse has adapted to loss of CERK in regards to airway hyper-responsiveness as compared with CERK siRNA treatment. Overall, we demonstrate that there are significant differences in eicosanoid levels in ex vivo CERK−/− cells compared with wild-type counterparts, but the effect of the genetic ablation of CERK on eicosanoid synthesis and the serum levels of C1P was not apparent in vivo.

Cytosolic phospholipase A2 (cPLA2) is activated by phosphorylation at serine-505 (S505) by extracellular regulated kinase 1/2 (ERK1/2). However, rat brain calcium/calmodulin-dependent kinase II (CaMKII) phosphorylates recombinant cPLA2 at serine-515 (S515) and increases its activity in vitro. We have studied the sites of cPLA2 phosphorylation and their significance in arachidonic acid (AA) release in response to norepinephrine (NE) in vivo in rabbit vascular smooth muscle cells (VSMCs) using specific anti-phospho-S515- and -S505 cPLA2 antibodies and by mutagenesis of S515 and S505 to alanine. NE increased the phosphorylation of cPLA2 at S515, followed by phosphorylation of ERK1/2 and consequently phosphorylation of cPLA2 at S505. The CaMKII inhibitor 2-[N-(2-hydroxyethyl)]-N-(4-methoxybenzene-sulfonyl)]amino-N-(4-chlorocinnamyl)-methylbenzylamine attenuated cPLA2 at S515 and S505, whereas the ERK1/2 inhibitor U0126 reduced phosphorylation at S505 but not at S515. NE in cells transduced with adenovirus carrying enhanced cyan fluorescent protein cPLA2 wild type caused phosphorylation at S515 and S505 and increased AA release. Expression of the S515A mutant in VSMCs reduced the phosphorylation of S505, ERK1/2, and AA release in response to NE. Transduction with a double mutant (S515A/S505A) blocked the phosphorylation of cPLA2 and AA release. These data suggest that the NE-stimulated phosphorylation of cPLA2 at S515 is required for the phosphorylation of S505 by ERK1/2 and that both sites of phosphorylation are important for AA release in VSMCs.

Recent data have revealed that soluble oligomeric amyloid-β peptide (Aβ) may be the proximate effectors of neuronal injuries and death in Alzheimer's disease (AD) by unknown mechanisms. Consistently, we recently demonstrated the critical role of a redox-sensitive cytosolic calcium-dependent phospholipase A2 (cPLA2)-arachidonic acid (AA) pathway in Aβ oligomer-induced cell death. According to the involvement of oxidative stress and polyunsaturated fatty acids like AA in the regulation of sphingomyelinase (SMase) activity, the present study underlines the role of SMases in soluble Aβ-induced apoptosis. Soluble Aβ oligomers induced the activation of both neutral and acidic SMases, as demonstrated by the direct measurement of their enzymatic activities, by the inhibitory effects of both specific neutral and acidic SMase inhibitors, and by gene knockdown using antisense oligonucleotides. Furthermore, soluble Aβ-mediated activation of SMases and subsequent cell death were found to be inhibited by antioxidant molecules and a cPLA2-specific inhibitor or antisense oligonucleotide. We also demonstrate that sphingosine-1-phosphate is a potent neuroprotective factor against soluble Aβ oligomer-induced cell death and apoptosis by inhibiting soluble Aβ-induced activation of acidic sphingomyelinase. These results suggest that Aβ oligomers induce neuronal death by activating neutral and acidic SMases in a redox-sensitive cPLA2-AA pathway.