Search

Lysophosphatidylcholine (lysoPtdCho) is produced by the phospholipase A2-mediated hydrolysis of phosphatidylcholine and can stimulate proliferation and apoptosis of vascular smooth muscle cells. We examined the influence of fetal bovine serum (FBS) concentration in the culture medium on lysoPtdChomediated apoptosis and proliferation of human aortic smooth muscle cells (HASMCs) as well as on the activation of extracellular signal-regulated kinases (ERK)1/2. In the presence of 1% FBS, HASMC viability increased after lysoPtdCho treatment at 1 and 10 μM but decreased at 25 and 50 μM. However, lysoPtdCho increased HASMC viability in a dose-dependent manner in the presence of 10% FBS. The activity of caspase 3/7 in HASMCs was increased by 25 μM lysoPtdCho in the presence of 1% FBS, but not 10% FBS. Furthermore, lysoPtdCho at 1 and 10 μM triggered ERK1/2 phosphorylation in the presence of 1% FBS, but not at 10% FBS. Thus, lysoPtdCho-mediated HASMC apoptosis, proliferation, and ERK1/2 activation are dependent on the concentration of FBS. [ABSTRACT FROM AUTHOR]

Abstract Background The transformation of normal macrophage cells into lipid-laden foam cells is an important step in the progression of atherosclerosis. One major contributor to foam cell formation in vivo is the intracellular accumulation of cholesterol. Methods Here, we report the effects of various combinations of low-density lipoprotein, sterols, lipids and other factors on human macrophages, using an automated image analysis program to quantitatively compare single cell properties, such as cell size and lipid content, in different conditions. Results We observed that the addition of cholesterol caused an increase in average cell lipid content across a range of conditions. All of the sterol-lipid mixtures examined were capable of inducing increases in average cell lipid content, with variations in the distribution of the response, in cytotoxicity and in how the sterol-lipid combination interacted with other activating factors. For example, cholesterol and lipopolysaccharide acted synergistically to increase cell lipid content while also increasing cell survival compared with the addition of lipopolysaccharide alone. Additionally, ergosterol and cholesteryl hemisuccinate caused similar increases in lipid content but also exhibited considerably greater cytotoxicity than cholesterol. Conclusions The use of automated image analysis enables us to assess not only changes in average cell size and content, but also to rapidly and automatically compare population distributions based on simple fluorescence images. Our observations add to increasing understanding of the complex and multifactorial nature of foam-cell formation and provide a novel approach to assessing the heterogeneity of macrophage response to a variety of factors.

The major facilitator superfamily domain 2a protein was identified recently as a lysophosphatidylcholine (LPC) symporter with high affinity for LPC species enriched with DHA (LPC-DHA). To test the hypothesis that reproductive state and choline intake influence plasma LPC-DHA, we performed a post hoc analysis of samples available through 10 weeks of a previously conducted feeding study, which provided two doses of choline (480 and 930 mg/d) to non-pregnant (n 21), third-trimester pregnant (n 26), and lactating (n 24) women; all participants consumed 200 mg of supplemental DHA and 22 % of their daily choline intake as 2H-labelled choline. The effects of reproductive state and choline intake on total LPC-DHA (expressed as a percentage of LPC) and plasma enrichments of labelled LPC and LPC-DHA were assessed using mixed and generalised linear models. Reproductive state interacted with time (P = 0·001) to influence total LPC-DHA, which significantly increased by week 10 in non-pregnant women, but not in pregnant or lactating women. Contrary to total LPC-DHA, patterns of labelled LPC-DHA enrichments were discordant between pregnant and lactating women (P < 0·05), suggestive of unique, reproductive state-specific mechanisms that result in reduced production and/or enhanced clearance of LPC-DHA during pregnancy and lactation. Regardless of the reproductive state, women consuming 930 v. 480 mg choline per d exhibited no change in total LPC-DHA but higher d3-LPC-DHA (P = 0·02), indicating that higher choline intakes favour the production of LPC-DHA from the phosphatidylethanolamine N -methyltransferase pathway of phosphatidylcholine biosynthesis. Our results warrant further investigation into the effect of reproductive state and dietary choline on LPC-DHA dynamics and its contribution to DHA status. [ABSTRACT FROM AUTHOR]

Background: Pancreaticobiliary maljunction and intrahepatic gallstones are at a high risk for biliary malignancy. Lysophosphatidylcholine (LPC) is increased in the bile of these patients, and we have previously reported that LPC‐induced cytotoxicity causes senescence‐associated secretory phenotype (SASP) in cholangiocytes. We aimed to determine the protective effect of phosphatidylcholine (PC) on LPC‐induced cholangiocyte cytotoxicity. Methods: MMNK‐1, a human immortalized cholangiocyte cell line was treated with LPC with or without PC. To assess the biological effects of SASP components on cholangiocarcinoma, HuH28 and HuCCT1 (human cholangiocarcinoma cell lines) were cultured in the conditioned media where MMNK‐1 cells treated with LPC. Results: The presence of PC reduced reactive oxygen species generation and oxidative DNA damage in MMNK‐1 treated with LPC. Moreover, SA‐β‐gal activity was markedly downregulated by PC. The secretion of SASP components, including interleukin (IL)‐8, IL‐6, and C‐C motif chemokine ligand 2 was also substantially reduced in the presence of PC. Cellular proliferation and migration were enhanced in HuCCT1 and HuH28 cells when cultured in the conditioned media, and these observations were suppressed by simultaneous addition of PC. Conclusion: PC protects cholangiocytes against LPC‐induced cytotoxicity and cellular senescence, suggesting its potential as a target for inhibiting LPC‐related carcinogenesis and its promotion. [ABSTRACT FROM AUTHOR]

Multiple sclerosis (MS) is an inflammatory disease characterized by myelin loss. While therapies exist to slow MS progression, no treatment currently exists for remyelination. Remyelination, linked to reduced disability in MS, relies on microglia and monocyte-derived macrophages (MDMs). This study aims to understand the role of microglia during remyelination by lineage tracing and depleting them. Microglial lineage tracing reveals that both microglia and MDMs initially accumulate, but microglia later dominate the lesion. Microglia and MDMs engulf equal amounts of inhibitory myelin debris, but after microglial depletion, MDMs compensate by engulfing more myelin debris. Microglial depletion does, however, reduce the recruitment and proliferation of oligodendrocyte progenitor cells (OPCs) and impairs their subsequent differentiation and remyelination. These findings underscore the essential role of microglia during remyelination and offer insights for enhancing this process by understanding microglial regulation of remyelination. [Display omitted] • Microglia and monocyte-derived macrophages engulf equal volumes of myelin debris • Macrophages compensate to remove myelin debris when microglia are depleted • Microglia facilitate oligodendrocyte progenitor cell proliferation • Microglia promote oligodendrocyte differentiation and remyelination Baaklini et al. demonstrate that, after demyelination, microglia and monocyte-derived macrophages engulf equal volumes of myelin debris. They found that microglia depletion did not impact myelin debris clearance because monocyte-derived macrophages could compensate. They found that microglia did promote oligodendrocyte progenitor cell recruitment and their subsequent differentiation and remyelination. [ABSTRACT FROM AUTHOR]

Inflammatory bowel diseases (IBD) comprise a distinct set of clinical symptoms resulting from chronic inflammation within the gastrointestinal (GI) tract. Despite the significant progress in understanding the etiology and development of treatment strategies, IBD remain incurable for thousands of patients. Metabolic deregulation is indicative of IBD, including substantial shifts in lipid metabolism. Recent data showed that changes in some phospholipids are very common in IBD patients. For instance, phosphatidylcholine (PC)/phosphatidylethanolamine (PE) and lysophosphatidylcholine (LPC)/PC ratios are associated with the severity of the inflammatory process. Composition of phospholipids also changes upon IBD towards an increase in arachidonic acid and a decrease in linoleic and a-linolenic acid levels. Moreover, an increase in certain phospholipid metabolites, such as lysophosphatidylcholine, sphingosine-1-phosphate and ceramide, can result in enhanced intestinal inflammation, malignancy, apoptosis or necroptosis. Because some phospholipids are associated with pathogenesis of IBD, they may provide a basis for new strategies to treat IBD. Current attempts are aimed at controlling phospholipid and fatty acid levels through the diet or via pharmacological manipulation of lipid metabolism.

Both calcium-independent phospholipase A2 beta (iPLA2β) and endoplasmic reticulum (ER) stress regulate important pathophysiological processes including inflammation, calcium homeostasis and apoptosis. However, their roles in ischemic heart disease are poorly understood. Here, we show that the expression of iPLA2β is increased during myocardial ischemia/reperfusion (I/R) injury, concomitant with the induction of ER stress and the upregulation of cell death. We further show that the levels of iPLA2β in serum collected from acute myocardial infarction (AMI) patients and in samples collected from both in vivo and in vitro I/R injury models are significantly elevated. Further, iPLA2β knockout mice and siRNA mediated iPLA2β knockdown are employed to evaluate the ER stress and cell apoptosis during I/R injury. Additionally, cell surface protein biotinylation and immunofluorescence assays are used to trace and locate iPLA2β. Our data demonstrate the increase of iPLA2β augments ER stress and enhances cardiomyocyte apoptosis during I/R injury in vitro and in vivo. Inhibition of iPLA2β ameliorates ER stress and decreases cell death. Mechanistically, iPLA2β promotes ER stress and apoptosis by translocating to ER upon myocardial I/R injury. Together, our study suggests iPLA2β contributes to ER stress-induced apoptosis during myocardial I/R injury, which may serve as a potential therapeutic target against ischemic heart disease.

Lysophosphatidic acids (LysoPAs) and lysophosphatidylserine (LysoPS) are emerging lipid mediators proposed to be involved in the pathogenesis of acute coronary syndrome (ACS). In this study, we attempted to elucidate how LysoPA and LysoPS become elevated in ACS using human blood samples collected simultaneously from culprit coronary arteries and peripheral arteries in ACS subjects. We found that: 1) the plasma LysoPA, LysoPS, and lysophosphatidylglycerol levels were not different, while the lysophosphatidylcholine (LysoPC), lysophosphatidylinositol, and lysophosphatidylethanolamine (LysoPE) levels were significantly lower in the culprit coronary arteries; 2) the serum autotaxin (ATX) level was lower and the serum phosphatidylserine-specific phospholipase A1 (PS-PLA1) level was higher in the culprit coronary arteries; 3) the LysoPE and ATX levels were significant explanatory factors for the mainly elevated species of LysoPA, except for 22:6 LysoPA, in the peripheral arteries, while the LysoPC and LysoPE levels, but not the ATX level, were explanatory factors in the culprit coronary arteries; and 4) 18:0 and 18:1 LysoPS were significantly correlated with PS-PLA1 only in the culprit coronary arteries. In conclusion, the origins of LysoPA and LysoPS might differ between culprit coronary arteries and peripheral arteries, and substrates for ATX, such as LysoPC and LysoPE, might be important for the generation of LysoPA in ACS.

Candida albicans is a commensal fungus, opportunistic pathogen, and the most common cause of fungal infection in humans. The biosynthesis of phosphatidylcholine (PC), a major eukaryotic glycerophospholipid, occurs through two primary pathways. In Saccharomyces cerevisiae and some plants, a third PC synthesis pathway, the PC deacylation/reacylation pathway (PC-DRP), has been characterized. PC-DRP begins with the acylation of the lipid turnover product, glycerophosphocholine (GPC), by the GPC acyltransferase, Gpc1, to form Lyso-PC. Lyso-PC is then acylated by lysolipid acyltransferase, Lpt1, to produce PC. Importantly, GPC, the substrate for Gpc1, is a ubiquitous metabolite available within the host. GPC is imported by C. albicans, and deletion of the major GPC transporter, Git3, leads to decreased virulence in a murine model. Here we report that GPC can be directly acylated in C. albicans by the protein product of orf19.988, a homolog of ScGpc1. Through lipidomic studies, we show loss of Gpc1 leads to a decrease in PC levels. This decrease occurs in the absence of exogenous GPC, indicating that the impact on PC levels may be greater in the human host where GPC is available. A gpc1Δ/Δ strain exhibits several sensitivities to antifungals that target lipid metabolism. Furthermore, loss of Gpc1 results in both a hyphal growth defect in embedded conditions and a decrease in long-term cell viability. These results demonstrate for the first time the importance of Gpc1 and this alternative PC biosynthesis route (PC-DRP) to the physiology of a pathogenic fungus., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Vitamins D have various biological activities, as well as intestinal calcium absorption. There has been recent concern about insufficient vitamin D intake. In addition to vitamins D2 and D3, there are lesser-known vitamins D4–D7. We synthesized vitamins D5–D7, which are not commercially available, and then evaluated and compared the mixed micelles-solubilized vitamins D uptake by Caco-2 cells. Except for vitamin D5, the uptake amounts of vitamins D4–D7 by differentiated Caco-2 cells were similar to those of vitamins D2 and D3. The facilitative diffusion rate in the ezetimibe inhibited pathway was approximately 20% for each vitamin D type, suggesting that they would pass through the pathway at a similar rate. Lysophosphatidylcholine enhanced each vitamin D uptake by approximately 2.5-fold. Lysophosphatidylcholine showed an enhancing effect on vitamin D uptake by reducing the intercellular barrier formation of Caco-2 cells by reducing cellular cholesterol, suggesting that increasing the uptakes of vitamins D and/or co-ingesting them with lysophosphatidylcholine, would improve vitamin D insufficiency. The various biological activities in the activated form of vitamins D4–D7 were estimated by Prediction of Activity Spectra for Substances (PASS) online simulation. These may have some biological activities, supporting the potential as nutritional components.

The stimulation of the immune response to prevent the progression of an infection may be an adjuvant to antimicrobial treatment. Here, we aimed to evaluate the efficacy of lysophosphatidylcholine (LPC) treatment in combination with colistin in murine experimental models of severe infections by Acinetobacter baumannii. We used the A. baumannii Ab9 strain, susceptible to colistin and most of the antibiotics used in clinical settings, and the A. baumannii Ab186 strain, susceptible to colistin but presenting a multidrug-resistant (MDR) pattern. The therapeutic efficacies of one and two LPC doses (25 mg/kg/d) and colistin (20 mg/kg/8 h), alone or in combination, were assessed against Ab9 and Ab186 in murine peritoneal sepsis and pneumonia models. One and two LPC doses combined with colistin and colistin monotherapy enhanced Ab9 and Ab186 clearance from spleen, lungs and blood and reduced mice mortality compared with those of the non-treated mice group in both experimental models. Moreover, one and two LPC doses reduced the bacterial concentration in tissues and blood in both models and increased mice survival in the peritoneal sepsis model for both strains compared with those of the colistin monotherapy group. LPC used as an adjuvant of colistin treatment may be helpful to reduce the severity and the resolution of the MDR A. baumannii infection.

Trypanosoma cruzi is the etiological agent of Chagas disease. These parasites undergo dramatic morphological and physiological changes during their life cycle. The human-infective metacyclic trypomastigotes differentiate from epimastigotes inside the midgut of the Triatominae insect vector. Our group has shown that the saliva and feces of Rhodnius prolixus contains a lysophospholipid, lysophosphatidylcholine (LPC), which modulates several aspects of T. cruzi infection in macrophages. LPC hydrolysis by a specific lysophospholipase D, autotaxin (ATX), generates lysophosphatidic acid (LPA). These bioactive lysophospholipids are multisignaling molecules and are found in human plasma ingested by the insect during blood feeding. Here, we show the role of LPC and LPA in T. cruzi proliferation and differentiation. Both lysophospholipids are able to induce parasite proliferation. We observed an increase in parasite growth with different fatty acyl chains, such as C18:0, C16:0, or C18:1 LPC. The dynamics of LPC and LPA effect on parasite proliferation was evaluated in vivo through a time- and space-dependent strategy in the vector gut. LPC but not LPA was also able to affect parasite metacyclogenesis. Finally, we determined LPA and LPC distribution in the parasite itself. Such bioactive lipids are associated with reservosomes of T. cruzi. To the best of our knowledge, this is the first study to suggest the role of surrounding bioactive lipids ingested during blood feeding in the control of parasite transmission. [ABSTRACT FROM AUTHOR]

Lysophosphatidylcholine (lysoPtdCho) is produced mainly by the phospholipase A2‐dependent hydrolysis of phosphatidylcholine (PtdCho) and can induce inflammatory activation and osteogenic gene expression in vascular smooth muscle cells. However, the mechanisms mediating these processes have not been fully elucidated. In this study, we investigated whether inhibition of protein kinase A (PKA) signaling suppressed lysoPtdCho‐induced calcification of human aortic smooth muscle cells (HASMC). Calcium levels and alkaline phosphatase activity were significantly increased in HASMC treated with lysoPtdCho, but not PtdCho, compared with those in phosphate‐buffered saline‐treated HASMC. However, the addition of a PKA inhibitor (H‐89) or PKA siRNA blocked lysoPtdCho‐induced HASMC calcification. These results showed that lysoPtdCho could activate PKA‐mediated HASMC calcification and that PKA may be a therapeutic target for lysoPtdCho‐mediated vascular smooth muscle cell calcification. [ABSTRACT FROM AUTHOR]

A quantification system for lysophospholipids (lysoPL) was developed, especially for blood samples, using liquid chromatography–tandem mass spectrometry (LC–MS/MS). However, the lysoPL measurement in cerebrospinal fluid (CSF) has not been validated. Therefore, the present study aimed to validate the lysoPL measurement using CSF samples and to elucidate the possible clinical significance of the lysoPL measurement in CSF. For the validation, we observed a good precision and linearity in a sample with high lysoPL levels. The concentrations of lysoPL changed after incubation but the changes were smaller than those observed for serum samples. Moreover, we observed that the CSF levels of 16:0, 18:0 lysophosphatidylcholine, and 18:0, 18:1, and 20:4 lysophosphatidic acid were significantly higher in subjects with central nervous system invasion caused by hematological malignancies or carcinoma than in subjects with no abnormal CSF test results. In conclusion, an LC–MS/MS quantification system for lysoPL in CSF might be useful and could be applied to clinical laboratory testing. [ABSTRACT FROM AUTHOR]

The possibility of improving brain function coupled with its preferential uptake in the brain has garnered attention for docosahexaenoic acid-bound lysophosphatidylcholine (DHA-LPC). However, studies focusing on the health benefits of dietary DHA-LPC are lacking. We prepared a dietary oil rich in DHALPC (DHA-LPC rich oil) via enzymatic modification of phospholipids (PL) extracted from squid (Todarodes pacificus) meal and purification of active carbon, ion exchange resin, and silica gel. We then examined the effects of dietary DHA-LPC rich oil on male Wistar rats by evaluating serum and liver lipid profiles, fatty acid (FA) metabolizing enzyme activity, and the FA composition of serum and brain. The rats were fed a basal diet containing either soybean oil alone (7%) or soybean oil (4.5%) with DHA-LPC rich oil (2.5%) for 28 days, and then evaluated. The rats fed the diet containing DHA-LPC rich oil showed reduced triacylglycerol concentration due, in part, to the enhancement of carnitine palmitoyltransferase 2 and acyl- CoA oxidase activities and suppression of acetyl-CoA carboxylase and glucose-6-phosphate dehydrogenase activities in the liver. Moreover, the dietary DHA-LPC rich oil moderately increased DHA in the FA composition of the rat hippocampus, which may be due to elevated DHA composition in serum LPC. These results suggest that DHA-LPC rich oil has hypolipidemic effect and moderate increase in hippocampal DHA amount in normal rats. [ABSTRACT FROM AUTHOR]

Background and Aims: Lipotoxicity causes liver inflammation, which leads to non‐alcoholic steatohepatitis (NASH). Lysophosphatidylcholine (LPC) is a causal agent of lipotoxicity. Recently, lysophosphatidylcholine acyltransferase (LPCAT) was identified as an enzyme that catalyzes the esterification of LPC, which potentially decreases LPC levels. However, the effect of LPCAT in lipotoxicity of the liver is not fully understood. Our aim was to determine whether LPCAT attenuates lipotoxicity in the liver. Methods: Mice fed a high‐fat diet with sucrose (HFDS) or high‐fat diet without sucrose, and Huh‐7 cells treated with palmitate were used. Results: Mice‐fed HFDS showed advanced liver fibrosis as compared with mice‐fed high‐fat diet or normal chow. Lysophosphatidylcholine acyltransferase 3 (LPCAT3) mRNA expression in the liver was significantly decreased in the HFDS liver, and LPC content in the HFDS liver was significantly increased as compared with the other groups. When Huh‐7 cells with short hairpin RNA‐mediated knockdown of LPCAT3 (shLPCAT3 cells) were treated with palmitate, the intracellular LPC concentration and cell death were significantly higher than those in wild‐type Huh‐7 cells. Palmitate‐induced cell death in shLPCAT3 was attenuated by a combination of receptor‐interacting protein kinase 1 inhibitor with pan‐caspase inhibitor. In contrast, intracellular LPC and palmitate‐induced cell death were significantly lower in LPCAT3‐overexpressing Huh‐7 cells than in wild‐type cells. Conclusion: Depletion of LPCAT3 in a mouse model of NASH leads to caspase‐independent cell death, and LPCAT3 is a potential therapeutic target in NASH. [ABSTRACT FROM AUTHOR]

Abstract Inflammation and oxidative stress are the two processes crucial in atherogenesis. Platelet-activating factor acetylhydrolase (PAF-AH), a plasma lipoprotein-associated enzyme, degrades pro-inflammatory lipids generated within oxidatively modified lipoproteins. Extensive evidence shows that incretin-based drugs, a new class of anti-diabetic agents, can provide cardiovascular protection that cannot be attributed to their glucose-lowering effects. The present study was undertaken to determine whether the antiatherogenic effects of the GLP-1(glucagon-like peptide-1) receptor agonist (exenatide) and DPP-4(dipeptidyl peptidase-4) inhibitors (sitagliptin) may occur via the regulation of platelet-activating factor acetylhydrolase (PAF-AH) activity/mass and inhibition of low-density lipoprotein (LDL) oxidation in the fructose-fed rats. Normal and fructose-fed rats (8 wk) were treated (4 wk) with sitagliptin (5 and 10 mg/kg p.o.) or with exenatide (5 and 10 µg/kg, s.c.). Plasma PAF-AH activity and phosphatidylcholine (PC) concentration were measured colorimetrically. Plasma PAF-AH concentration, oxidized LDL (oxLDL), hexanoyl-Lys adduct (HEL), lyso-PC, apolipoprotein A-I (apoA-I), apoB, platelet-activating factor (PAF), monocyte chemoattractant protein-1 (MCP-1) and endothelin-1 (ET-1) were measured by ELISA. The four-week exenatide (5 µg/kg, sc.) treatment of fructose fed-rats significantly increased plasma PAF-AH activity (+33%, P < 0.001) and decreased the level of circulating oxLDL (-42%, P < 0.05) and MCP-1 (-23%, P < 0.01). These changes were accompanied by the decrease in plasma PC/lyso-PC (-47%, P < 0.001) and apoB/apoA-I ratio (-75%, P < 0.001). The effect of exenatide on enzyme activity was associated with only a minor effect on metabolic parameters and was independent of weight reduction. Exenatide but not sitagliptin inhibits oxidative modification of LDL probably due to favorable effect on plasma PAF-AH activity. [ABSTRACT FROM AUTHOR]

Several years after its isolation from melanoma cells, an increasing body of experimental evidence has established the involvement of Autotaxin (ATX) in the pathogenesis of several diseases. ATX, an extracellular enzyme responsible for the hydrolysis of lysophosphatidylcholine (LPC) into the bioactive lipid lysophosphatidic acid (LPA), is overexpressed in a variety of human metastatic cancers and is strongly implicated in chronic inflammation and liver toxicity, fibrotic diseases, and thrombosis. Accordingly, the ATX‐LPA signaling pathway is considered a tractable target for therapeutic intervention substantiated by the multitude of research campaigns that have been successful in identifying ATX inhibitors by both academia and industry. Furthermore, from a therapeutic standpoint, the entry and the so far promising results of the first ATX inhibitor in advanced clinical trials against idiopathic pulmonary fibrosis (IPF) lends support to the viability of this approach, bringing it to the forefront of drug discovery efforts. The present review article aims to provide a comprehensive overview of the most important series of ATX inhibitors developed so far. Special weight is lent to the design, structure activity relationship and mode of binding studies carried out, leading to the identification of advanced leads. The most significant in vitro and in vivo pharmacological results of these advanced leads are also summarized. Lastly, the development of the first ATX inhibitor entered in clinical trials accompanied by its phase 1 and 2a clinical trial data is disclosed. [ABSTRACT FROM AUTHOR]

Abstract Demyelination in white matter is the end product of numerous pathological processes. This study was designed to evaluate the neuroprotective effect of l -serine and the underlying mechanisms against the demyelinating injury of white matter. A model of focal demyelinating lesions (FDL) was established using the two-point stereotactic injection of 0.25% lysophosphatidylcholine (LPC, 10 μg per point) into the corpus callosum of mice. Mice were then intraperitoneally injected with one of three doses of l -serine (114, 342, or 1026 mg/kg) 2 h after FDL, and then twice daily for the next five days. Behavior tests and histological analysis were assessed for up to twenty-eight days post-FDL induction. Electron microscopy was used for ultrastructural investigation. In vitro , we applied primary co-cultures of microglia and oligodendrocytes for oxygen glucose deprivation (OGD). After establishing FDL, l -serine treatment: 1) improved spatial learning, memory and cognitive ability in mice, and relieved anxiety for 4 weeks post-FDL induction; 2) reduced abnormally dephosphorylated neurofilament proteins, increased myelin basic protein, and preserved anatomic myelinated axons; 3) inhibited microglia activation and reduced the release of inflammatory factors; 4) promoted recruitment and proliferation of oligodendrocyte progenitor cells, and the efficiency of subsequent remyelination on day twenty-eight post-FDL induction. In vitro experiments, showed that l -serine not only directly protected against oligodendrocytes from OGD damage, but also provided an indirect protective effect by regulating microglia. In our study, l -serine offered long-lasting behavioral and oligodendrocyte protection and promoted remyelination. Therefore, l -serine may be an effective clinical treatment aganist white matter injury. Highlights • l -serine has an outstanding therapeutic effect against LPC-induced white matter injury in mice. • l -serine offers long-lasting behavioral and oligodendrocyte protection and promotes remyelination. • l -serine could provide an additional protective effect by regulating microglia activation. [ABSTRACT FROM AUTHOR]

Objectives Acute aortic dissection (AAD) is a severe clinical emergency with a high mortality, and is easily misdiagnosed in its early stage. This study aimed at discovering serum metabolomic markers with the potential to diagnose AAD and distinguish between two subtypes of AAD. Methods Thirty-five patients with AAD, including 20 with Stanford type A and 15 with Stanford type B were enrolled in this study, together with 20 healthy controls. All patients with AAD were admitted within 72 h of onset. Serum metabolomics profiles were determined by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry and the data were analysed by principal component analysis and partial least squares discriminant analysis. Results A total of 17 metabolites differing between the control and AAD groups were finally screened and identified as lysophosphatidylcholines (LPC) and sphingolipids including sphinganine, phytosphingosine, sphingomyelin, and ceramide. Compared with those in the healthy control group, LPC levels were significantly lower in both the Stanford type A and type B AAD groups. Interestingly, sphingolipids, including sphinganine, phytosphingosine, and ceramide, were remarkably reduced in the Stanford type A AAD group, but not in the Stanford type B AAD group. Subgroup analysis showed that the changes in LPC and sphingolipid levels were unrelated to hypertension or gender. Conclusions The present results indicate that LPCs and sphingolipids are significantly altered in patients with AAD, and several sphingolipids, such as sphinganine, phytosphingosine, and ceramide, were dramatically decreased in patients with Stanford type A AAD. A combination of these two families of metabolites could serve as a potential biomarker for the diagnosis of AAD and distinguishing between Stanford type A and Stanford type B. [ABSTRACT FROM AUTHOR]

A pathological feature in atherosclerosis is the dysfunction and death of vascular endothelial cells (EC). Oxidized low‐density lipoprotein (LDL), known to accumulate in the atherosclerotic arterial walls, impairs endothelium‐dependent relaxation and causes EC apoptosis. A major bioactive ingredient of the oxidized LDL is lysophosphatidylcholine (LPC), which at higher concentrations causes apoptosis and necrosis in various EC. There is hitherto no report on LPC‐induced cytotoxicity in brain EC. In this work, we found that LPC caused cytosolic Ca2+ overload, mitochondrial membrane potential decrease, p38 activation, caspase 3 activation and eventually apoptotic death in mouse cerebral bEND.3 EC. In contrast to reported reactive oxygen species (ROS) generation by LPC in other EC, LPC did not trigger ROS formation in bEND.3 cells. Pharmacological inhibition of p38 alleviated LPC‐inflicted cell death. We examined whether heparin could be cytoprotective: although it could not suppress LPC‐triggered Ca2+ signal, p38 activation and mitochondrial membrane potential drop, it did suppress LPC‐induced caspase 3 activation and alleviate LPC‐inflicted cytotoxicity. Our data suggest LPC apoptotic death mechanisms in bEND.3 might involve mitochondrial membrane potential decrease and p38 activation. Heparin is protective against LPC cytotoxicity and might intervene steps between mitochondrial membrane potential drop/p38 activation and caspase 3 activation. [ABSTRACT FROM AUTHOR]

Background: Gait speed is an important measure of lower extremity physical performance in older adults and is predictive of disability and mortality. The biological pathways involved in the decline of lower extremity physical performance are not well understood. We used a targeted metabolomics approach to identify plasma metabolites predictive of change in gait speed over time.Methods: Gait speed was measured at baseline and over median follow-up of 50.5 months in 504 adults, aged ≥50 years, who had two or more study visits in the Baltimore Longitudinal Study of Aging (BLSA). Plasma metabolites were measured using targeted mass spectrometry (AbsoluteIDQ p180 Kit, Biocrates).Results: Of 148 plasma metabolites (amino acids, biogenic amines, hexoses, glycerophospholipids) measured, eight were significantly associated with gait speed at baseline, independent of age and sex: hexoses (r = -0.148, p < .001), [sphingomyelin (SM) 16:1 (r = -0.091, p = .0009), SM 18:0 (r = -0.085, p = .002), SM 18:1 (r = -0.128, p < .0001], phosphatidylcholine aa 32:3 (r = -0.088, p = .001), lysophosphatidylcholine (LPC) 17:0 (r = 0.083, p = .003), LPC 18:1 (r = 0.089, p = .001), and LPC 18:2 (r = 0.104, p < .0001). Adjusting for baseline age, sex, and chronic diseases, baseline plasma LPC 18:2 was an independent predictor of the rate of change of gait speed over subsequent follow-up (p = .003). No other plasma metabolites were significantly associated longitudinal changes of gait speed over time.Conclusions: Low plasma LPC 18:2, which has previously been shown to predict impaired glucose tolerance, insulin resistance, type 2 diabetes, coronary artery disease, and memory impairment, is an independent predictor of decline in gait speed in older adults. [ABSTRACT FROM AUTHOR]

Lysophosphatidylcholine (LysoPC) has been shown to induce the expression of inflammatory proteins, including cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6), associated with cardiac fibrosis. Here, we demonstrated that LysoPC-induced COX-2 and IL-6 expression was inhibited by silencing NADPH oxidase 1, 2, 4, 5; p65; and FoxO1 in human cardiac fibroblasts (HCFs). LysoPC-induced IL-6 expression was attenuated by a COX-2 inhibitor. LysoPC-induced responses were mediated via the NADPH oxidase-derived reactive oxygen species-dependent JNK1/2 phosphorylation pathway, leading to NF-κB and FoxO1 activation. In addition, we demonstrated that both FoxO1 and p65 regulated COX-2 promoter activity stimulated by LysoPC. Overexpression of wild-type FoxO1 and S256D FoxO1 enhanced COX-2 promoter activity and protein expression in HCFs. These results were confirmed by ex vivo studies, where LysoPC-induced COX-2 and IL-6 expression was attenuated by the inhibitors of NADPH oxidase, NF-κB, and FoxO1. Our findings demonstrate that LysoPC-induced COX-2 expression is mediated via NADPH oxidase-derived reactive oxygen species generation linked to the JNK1/2-dependent pathway leading to FoxO1 and NF-κB activation in HCFs. LysoPC-induced COX-2-dependent IL-6 expression provided novel insights into the therapeutic targets of the cardiac fibrotic responses. [ABSTRACT FROM AUTHOR]

The major facilitator superfamily domain-containing protein 2A (MFSD2A) is a constituent of the blood-brain barrier and functions to transport lysophosphatidylcholines (LPCs) into the central nervous system. LPCs such as that derived from docosahexanoic acid (DHA) are indispensable to neurogenesis and maintenance of neurons, yet cannot be synthesized within the brain and are dependent on MFSD2A for brain uptake. Recent studies have implicated MFSD2A mutations in lethal and non-lethal microcephaly syndromes, with the severity correlating to the residual activity of the transporter. We describe two siblings with shared parental ancestry, in whom we identified a homozygous missense mutation (c.1205C > A; p.Pro402His) in MFSD2A. Both affected individuals had microcephaly, hypotonia, appendicular spasticity, dystonia, strabismus, and global developmental delay. Neuroimaging revealed paucity of white matter with enlarged lateral ventricles. Plasma lysophosphatidylcholine (LPC) levels were elevated, reflecting reduced brain transport. Cell-based studies of the p.Pro402His mutant protein indicated complete loss of activity of the transporter despite the non-lethal, attenuated phenotype. The aggregate data of MFSD2A-associated genotypes and phenotypes suggest that additional factors, such as nutritional supplementation or modifying genetic factors, may modulate the severity of disease and call for consideration of treatment options for affected individuals. [ABSTRACT FROM AUTHOR]

Highlights • Lysophosphatidylcholine (LPC) is associated with oxidation of low density lipoproteins (LDL) and atherosclerosis. • We elucidated RNA profiling from LPC treated THP-1 derived macrophages using RNA sequencing method. • The LPC affected the expression of genes involved in cholesterol synthesis pathways. • LPCs with saturated acyl groups is involved in cholesterol biosynthesis. Abstract Lysophosphatidylcholine (LPC), a major component of oxidized low-density lipoprotein, is associated with atherosclerosis, obesity, stroke, and cancer. However, the direction and mechanism of this relationship remains unclear. In this study, we conducted RNA profiling in THP-1 derived macrophages treated with LPC and uncovered a relationship between LPC and the cholesterol biosynthesis pathway. Principal component analysis (PCA) of RNA profiling showed that untreated THP-1 cells and those treated with 10, 20, or 40 µM LPC were distinctly distributed. Functional annotation revealed that LPC affected the expression of genes involved in cytokine–cytokine receptor interaction, TNF signaling, and MAPK signaling. Interestingly, LPC also altered the expression of 11 genes involved in cholesterol synthesis such as those in terpenoid backbone biosynthesis and steroid biosynthesis pathways. This increased gene expression occurred in a dose-dependent manner in response to LPC treatment. Especially, LPC with saturated acyl groups enhanced the expression of these genes compared to LPC with unsaturated acyl groups, and similar results were shown in response to saturated and unsaturated free fatty acids. Our findings demonstrate that LPCs with saturated acyl groups induce the expression of genes involved in cholesterol biosynthesis and may have implications for cholesterol related diseases. [ABSTRACT FROM AUTHOR]

We investigated the synthesis of N-docosahexaenoylethanolamine (synaptamide) in neuronal cells from unesterified docosahexaenoic acid (DHA) or DHA-lysophosphatidylcholine (DHA-lysoPC), the two major lipid forms that deliver DHA to the brain, in order to understand the formation of this neurotrophic and neuroprotective metabolite of DHA in the brain. Both substrates were taken up in Neuro2A cells and metabolized to N-docosahexaenoylphosphatidylethanolamine (NDoPE) and synaptamide in a time- and concentration-dependent manner, but unesterified DHA was 1.5 to 2.4 times more effective than DHA-lysoPC at equimolar concentrations. The plasmalogen NDoPE (pNDoPE) amounted more than 80% of NDoPE produced from DHA or DHA-lysoPC, with 16-carbon-pNDoPE being the most abundant species. Inhibition of N-acylphosphatidylethanolamine-phospholipase D (NAPE-PLD) by hexachlorophene or bithionol significantly decreased the synaptamide production, indicating that synaptamide synthesis is mediated at least in part via NDoPE hydrolysis. NDoPE formation occurred much more rapidly than synaptamide production, indicating a precursor–product relationship. Although NDoPE is an intermediate for synaptamide biosynthesis, only about 1% of newly synthesized NDoPE was converted to synaptamide, possibly suggesting additional biological function of NDoPE, particularly for pNDoPE, which is the major form of NDoPE produced.

Lysophosphatidic acid (LPA) is a bioactive lysophospholipid that is a notable biomarker of kidney injury. However, it is not clear how LPA is produced in renal cells. In this study, we explored LPA generation and its enzymatic pathway in a rat kidney-derived cell, NRK52E cells. Culturing of NRK52E cells with acyl lysophosphatidylcholine (acyl LPC), or lyso-platelet activating factor (lysoPAF, alkyl LPC) was resulted in increased extracellular level of choline, co-product with LPA by lysophospholipase D (lysoPLD). Their activities were enhanced by addition of calcium ions to the cell culture medium, but failed to be inhibited by S32826, an autotaxin (ATX)-specific inhibitor. Liquid chromatography-tandem mass spectrometric analysis revealed the small, but significant extracellular production of acyl LPA/cyclic phosphatidic acid (cPA) and alkyl LPA/cPA. The mRNA expression of glycerophosphodiesterase (GDE) 7 with lysoPLD activity was elevated in confluent NRK52E cells cultured over 3 days. GDE7 plasmid-transfection of NRK52E cells augmented both extracellular and intracellular productions of LPAs (acyl and alkyl) as well as extracellular productions of cPAs (acyl and alkyl) from exogenous LPCs (acyl and alkyl). These results suggest that intact NRK52E cells are able to produce choline and LPA/cPA from exogenous LPCs through the enzymatic action of GDE7 that is located on the plasma membranes and intracellular membranes. • NRK52E cells produce choline from exogenously added lysophosphatidylcholine (LPC). • NRK52E cells produce lysophosphatidic acid (LPA) and cyclic phosphatidic acid (cPA). • Intracellular productions of LPA and cPA from LPC exposed to NRK52E cells • Confluent NRK52E cells express more mRNAs of glycerophosphodiesterase 7 (GDE7). • GDE7-transfection of NRK52E cells augmented productions of LPA/cPA/choline. [ABSTRACT FROM AUTHOR]

The saturated LPC18:0 and unsaturated LPC18:1 lysophosphatidylcholines have important roles in inflammation and immunity and are interesting targets for immunotherapy. The synthetic cationic lipid DODAB has been successfully employed in delivery systems, and would be a suitable carrier for those lysophosphatidylcholines. Here, assemblies of DODAB and LPC18:0 or LPC18:1 were characterized by Differential Scanning Calorimetry (DSC) and Electron Paramagnetic Resonance (EPR) spectroscopy. LPC18:0 increased the DODAB gel-fluid transition enthalpy and rigidified both phases. In contrast, LPC18:1 caused a decrease in the DODAB gel-fluid transition temperature and cooperativity, associated with two populations with distinct rigidities in the gel phase. In the fluid phase, LPC18:1 increased the surface order but, differently from LPC18:0, did not affect viscosity at the membrane core. The impact of the different acyl chains of LPC18:0 and 18:1 on structure and thermotropic behavior should be considered when developing applications using mixed DODAB membranes. [Display omitted] • DODAB vesicle structure can be modulated by lysophosphatidylcholine acyl chain. • Saturated lysophosphatidylcholine rigidified the gel phase of cationic membranes. • Unsaturated lysophosphatidylcholine destabilized the gel phase. • Saturated lysophosphatidylcholine rigidified the fluid phase of cationic membranes. • Unsaturated lysophosphatidylcholine rigidified the surface of the fluid phase. [ABSTRACT FROM AUTHOR]

Mouse chow supplemented with lysophosphatidylcholine with oleic acid at sn-1 and a hydroxyl group at sn-2 (LysoPC 18:1) increased LysoPC 18:1 in tissue of the jejunum of LDL receptor (LDLR)-null mice by 8.9 ± 1.7-fold compared with chow alone. Western diet (WD) contained dramatically less phosphatidylcholine 18:1 or LysoPC 18:1 compared with chow, but feeding WD increased LysoPC 18:1 in the jejunum by 7.5 ± 1.4-fold compared with chow. Feeding LysoPC 18:1 or feeding WD increased oxidized phospholipids in the jejunum by 5.2 ± 3.0-fold or 8.6 ± 2.2-fold, respectively, in LDLR-null mice (P < 0.0004), and 2.6 ± 1.5-fold or 2.4 ± 0.92-fold, respectively, in WT C57BL/6J mice (P < 0.0001). Adding 0.06‥ by weight of a concentrate of transgenic tomatoes expressing the 6F peptide (Tg6F) decreased LysoPC 18:1 in the jejunum of LDLR-null mice on both diets (P < 0.0001), and prevented the increase in oxidized phospholipids in the jejunum in LDLR-null and WT mice on both diets (P < 0.008). Tg6F decreased inflammatory cells in the villi of the jejunum, decreased dyslipidemia, and decreased systemic inflammation in LDLR-null and WT mice on both diets. We conclude that Tg6F reduces diet-induced inflammation by reducing the content of unsaturated LysoPC and oxidized phospholipids in the jejunum of mice.

The influence of the hypercholesterolemia associated with atherosclerosis on monocytes is poorly understood. Monocytes are exposed to high concentrations of lipids, particularly cholesterol and lysophosphatidylcholine (lyso-PC). Indeed, in line with recent reports, we found that monocytes accumulate cholesteryl esters (CEs) in hypercholesterolemic mice, demonstrating the need for studies that analyze the effects of lipid accumulation on monocytes. Here we analyze the effects of cholesterol and lyso-PC loading in human monocytes and macrophages. We found that cholesterol acyltransferase and CE hydrolase activities are lower in monocytes. Monocytes also showed a different expression profile of cholesterol influx and efflux genes in response to lipid loading and a different pattern of lyso-PC metabolism. In monocytes, increased levels of CE slowed the conversion of lyso-PC into PC. Interestingly, although macrophages accumulated glycerophosphocholine, phosphocholine was the main water-soluble choline metabolite being generated in monocytes, suggesting a role for mono- and diacylglycerol in the chemoattractability of these cells. In summary, monocytes and macrophages show significant differences in lipid metabolism and gene expression profiles in response to lipid loading. These findings provide new insights into the mechanisms of atherosclerosis and suggest potentials for targeting monocyte chemotactic properties not only in atherosclerosis but also in other diseases.

Oxidized low-density lipoprotein (oxLDL) and oxidized high-density lipoprotein (oxHDL), known as risk factors for cardiovascular disease, have been observed in plasma and atheromatous plaques. In a previous study, the content of oxidized phosphatidylcholine (oxPC) and lysophosphatidylcholine (lysoPC) species stayed constant in isolated in vivo oxLDL but increased in copper-induced oxLDL in vitro. In this study, we prepared synthetic deuterium-labeled 1-palmitoyl lysoPC and palmitoyl-glutaroyl PC (PGPC), a short chain-oxPC to elucidate the metabolic fate of oxPC and lysoPC in oxLDL in the presence of HDL. When LDL preloaded with d13-lysoPC was mixed with HDL, d13-lysoPC was recovered in both the LDL and HDL fractions equally. d13-LysoPC decreased by 50% after 4 h of incubation, while d13-PC increased in both fractions. Diacyl-PC production was abolished by an inhibitor of lecithin-cholesterol acyltransferase (LCAT). When d13-PGPC-preloaded LDL was incubated with HDL, d13-PGPC was transferred to HDL in a dose-dependent manner when both LCAT and lipoprotein-associated phospholipase A2 (Lp-PLA2) were inhibited. Lp-PLA2 in both HDL and LDL was responsible for the hydrolysis of d13-PGPC. These results suggest that short chain-oxPC and lysoPC can transfer between lipoproteins quickly and can be enzymatically converted from oxPC to lysoPC and from lysoPC to diacyl-PC in the presence of HDL.

Ginseng consumption has been shown to prevent and reduce many health risks, including cardiovascular disease. However, the ginseng-induced changes in biofluids and tissue metabolomes associated with blood health remain poorly understood. In this study, healthy rats were orally administered ginseng extracts or water for one month. Biofluid and tissue metabolites along with steroid hormones, plasma cytokines, and blood pressure factors were determined to elucidate the relationship between ginseng intake and blood vessel health. Moreover, the effect of ginseng extract on blood vessel tension was measured from the thoracic aorta. Ginseng intake decreased the levels of blood phospholipids, lysophosphatidylcholines and related enzymes, high blood pressure factors, and cytokines, and induced vasodilation. Moreover, ginseng intake decreased the level of renal oxidized glutathione. Overall, our findings suggest that ginseng intake can improve blood vessel health via modulation of vasodilation, oxidation stress, and pro-inflammatory cytokines. Moreover, the decrease in renal oxidized glutathione indicated that ginseng intake is positively related with the reduction in oxidative stress-induced renal dysfunction.

Lysophosphatidylcholines are a group of bioactive lipids heavily investigated in the context of inflammation and atherosclerosis development. While present in plasma during physiological conditions, their concentration can drastically increase in certain inflammatory states. Lysophosphatidylcholines are widely regarded as potent pro-inflammatory and deleterious mediators, but an increasing number of more recent studies show multiple beneficial properties under various pathological conditions. Many of the discrepancies in the published studies are due to the investigation of different species or mixtures of lysophatidylcholines and the use of supra-physiological concentrations in the absence of serum or other carrier proteins. Furthermore, interpretation of the results is complicated by the rapid metabolism of lysophosphatidylcholine (LPC) in cells and tissues to pro-inflammatory lysophosphatidic acid. Interestingly, most of the recent studies, in contrast to older studies, found lower LPC plasma levels associated with unfavorable disease outcomes. Being the most abundant lysophospholipid in plasma, it is of utmost importance to understand its physiological functions and shed light on the discordant literature connected to its research. LPCs should be recognized as important homeostatic mediators involved in all stages of vascular inflammation. In this review, we want to point out potential pro- and anti-inflammatory activities of lysophospholipids in the vascular system and highlight recent discoveries about the effect of lysophosphatidylcholines on immune cells at the endothelial vascular interface. We will also look at their potential clinical application as biomarkers.

Diabetes mellitus is a worldwide health problem with high rates of mortality and morbidity. Management of diabetes mellitus by dietary components is achievable especially at the initial stage of the disease. Several studies confirmed the antidiabetic activities of simple phenolic acids and lysophosphatidylcholine (LPC). The main goal of this study was to identify new potential insulin secretion modulators obtained by combining the structures of two natural compounds, namely O-methyl derivatives of phenolic acids and phospholipids. LPC and phosphatidylcholine bearing methoxylated aromatic carboxylic acids were tested as potential agents able to improve glucose-stimulated insulin secretion (GSIS) and intracellular calcium mobilization in MIN6 β pancreatic cell line. Our results show that LPC with covalently bonded molecule of p-anisic acid at the sn-1 position was able to induce GSIS and intracellular calcium flux. Notably, 1-anisoyl-2-hydroxy-sn-glycero-3-phosphocholine did not affect the viability of MIN6 cells, suggesting its potential safe use. Furthermore, we have shown that three G protein coupled receptors, namely GPR40, GPR55, and GPR119, are targeted by this LPC derivative.

Branched-chain amino acids (BCAAs) and lysophosphatidylcholines (LPCs) have been reported to be associated with diabetes. The purpose of the present study was to investigate the relative contributions of BCAAs and LPCs to the progression of prediabetes to diabetes using a targeted metabolomic approach. This study was part of a health survey of employees of the Electricity Generating Authority of Thailand (n = 79; nine females and 70 males). A targeted metabolomics analysis was performed using an AbsoluteIDQ® p180 kit, flow injection analysis, and liquid chromatography-tandem mass spectrometry. The highest variable importance in projection (VIP) scores for the progression to diabetes of the amino acids and phospholipids were associated with isoleucine and LPC acyl C28:1, respectively. Using logistic regression analysis, we found that high baseline isoleucine concentration was associated with a higher incidence of diabetes, while high LPC acyl 28:1 was associated with a lower incidence. Isoleucine and LPC acyl 28:1 were independently associated with incident diabetes in a model that also included conventional risk factors for diabetes (baseline fasting plasma glucose (FPG), age, sex, and body mass index (BMI)). In addition, isoleucine and LPC acyl 28:1 were independently associated with serum HbA1c 5 years later in a robust regression model that also included baseline FPG, age, sex, and BMI. Isoleucine, LPC acyl 28:1, age, and FPG were significantly associated with HbA1c at this time. In conclusion, these results provide evidence that isoleucine and LPC acyl C28:1 have respective positive and negative independent associations with incident diabetes.

Tuberculosis is caused by the infectious agent Mycobacterium tuberculosis (Mtb). Mtb has various survival strategies, including blockade of phagosome maturation and inhibition of antigen presentation. Lysophosphatidylcholine (LPC) is a major phospholipid component of oxidized low-density lipoprotein and is involved in various cellular responses, such as activation of second messengers and bactericidal activity in neutrophils. In this study, macrophages were infected with a low infectious dose of Mtb and treated with LPC to investigate the bactericidal activity of LPC against Mtb. In macrophages infected with Mtb strain, H37Ra or H37Rv, LPC suppressed bacterial growth; however, this effect was suppressed in bone marrow-derived macrophages (BMDMs) isolated from G2A (a G protein-coupled receptor involved in some LPC actions) knockout mice. LPC also promoted phagosome maturation via phosphatidylinositol 3 kinase (PI3K)–p38 mitogen-activated protein kinase (MAPK)-mediated reactive oxygen species production and intracellular Ca2+ release during Mtb infection. In addition, LPC induced increased levels of intracellular cyclic adenosine monophosphate (cAMP) and phosphorylated glycogen synthase kinase 3 beta (GSK3β) in Mtb-infected macrophages. Protein kinase A (PKA)-induced phosphorylation of GSK3β suppressed activation of NF-κB in LPC-treated macrophages during Mtb infection, leading to decreased secretion of pro-inflammatory cytokines and increased secretion of anti-inflammatory cytokines. These results suggest that LPC can effectively control Mtb growth by promoting phagosome maturation via cAMP-induced activation of the PKA–PI3K–p38 MAPK pathway. Moreover, LPC can regulate excessive production of pro-inflammatory cytokines associated with bacterial infection of macrophages.

ObjectivesImpaired clearance of dying and dead cells by professional and amateur phagocytes plays a crucial role in the etiology of systemic lupus erythematosus (SLE). While dying, cells expose and release a plethora of eat-me and find-me signals to ensure their timely removal before entering the dangerous stage of secondary necrosis. A well-described chemoattractant for macrophages is dying cell-derived lysophosphatidylcholine (LPC). However, its implications for and/or its association with SLE disease, so far, have not been examined. In the present study, we analyzed the LPC serum concentrations of patients with SLE and rheumatoid arthritis (RA). Subsequently, we examined if and to which extent the measured serum concentrations of LPC and an LPC-rich environment can impact the phagocytosis of necrotic cells.MethodsSera from patients with SLE, RA, and normal healthy donors (NHD) were characterized for several parameters, including LPC concentrations. Phagocytosis of dead cells by human macrophages in the presence of SLE and NHD sera was quantified. Additionally, the impact of exogenously added, purified LPC on phagocytosis was analyzed.ResultsPatients with SLE had significantly increased LPC serum levels, and high serum LPC of SLE patients correlated significantly with impaired phagocytosis of dead cells in the presence of heat-inactivated serum. Phagocytosis in the presence of sera from NHD showed no correlation to LPC levels, but exogenous addition of purified LPC in the range as measured in SLE patients’ sera led to a concentration-dependent decrease.ConclusionOur data show that high levels of LPC as observed in the sera of SLE patients have a negative impact on the clearance of dead cells by macrophages. Chemoattraction requires a concentration gradient. The higher the LPC concentration surrounding a dying or dead cell, the smaller the achievable gradient upon LPC release will be. Thus, it is feasible to assume that elevated LPC levels can interfere with the build-up of a local LPC gradient during cell death, and hence might play a role in the establishment and/or perpetuation of SLE disease.