Plasma Lysophosphatidylcholine and Phospholipase A2 Activity in Chagas Disease Patients: A Comparative Analysis

Chagas disease (CD) affects 21 countries in the Americas and is caused by the parasite Trypanosoma cruzi. A key molecule involved in CD is lysophosphatidylcholine (LPC), which has been studied in various contexts: in the saliva of insect vectors, during the establishment of infection in the vertebrate host, and for the parasite itself. This lipid can be produced by the action of phospholipases A2 (PLA2), enzymes that catalyze the hydrolysis of phospholipids releasing fatty acids and lysophospholipids, such as LPC. This study investigates LPC levels and PLA2 activities in the plasma of CD patients and compares these levels with those in healthy individuals and patients with idiopathic dilated cardiomyopathy (IDCM). Plasma from 64 CD patients, 54 healthy individuals, and 16 IDCM patients were analyzed. LPC levels and the activity of two types of phospholipase A2: secreted (sPLA2) and lipoprotein-associated (Lp-PLA2) were measured. LPC levels and sPLA2 activity were similar between CD patients and the control groups. However, there were notable differences in LPC levels and sPLA2 activity between subgroups of CD patients and IDCM patients. This study is the first to identify LPC in patients with CD across various stages of the disease. It also offers new insights into the biochemical changes observed in the plasma of patients with IDCM.

Effect of Lysophosphatidylcholine on ATP and ρ-Nitrophenyl Phosphate Hydrolysis by the Plasma Membrane H^+-ATPase from Soybean Hypocotyls

The stimulatory effect of lysophosphatidylcholine (lyso_PC) on ATP and ρ_nitrophenyl phosphate (PNPP) hydrolysis by the plasma membrane H +_ATPase from soybean (Glycine max (L.) Merr.) hypocotyls was studied. Results showed that lyso_PC stimulated the hydrolysis of ATP; ATP hydrolysis was enhanced dramatically when lyso_PC was within 0-0.03%, and increased slightly when lyso_PC was higher than 0.03%. At the concentration of 0.03%, lyso_PC stimulated ATP hydrolysis by 80.5%. Kinetics analysis showed that V max increased from 0.46 μmol P i·mg -1 protein·min -1 to 0.87 μmol P i·mg -1 protein·min -1 while K m increased from 0.88 mmol/L to 1.15 mmol/L under lyso_PC treatment. The optimum pH of ATP hydrolysis was shifted from 6.5 to 7.0 . Moreover, it was found lyso_PC enhanced the inhibition of ATP hydrolysis by hydroxylamine. In the presence of 200 mmol/L hydroxylamine, ATP hydrolysis was inhibited by 74.4%, while it was inhibited by 84.4% when treated with lyso_PC. However, PNPP hydrolysis and the inhibitory effect of vanadate were not affected by lyso_PC. The above results indicated that the kinase domain might be an action site or regulatory region of the C_terminal autoinhibitory domain in the plant plasma membrane H +_ATPase.

Baseline effects of lysophosphatidylcholine and nerve growth factor in a rat model of sciatic nerve regeneration after crush injury

Schwann cells play a major role in helping heal injured nerves. They help clear debris, produce neurotrophins, upregulate neurotrophin receptors, and form bands of Büngner to guide the healing nerve. But nerves do not always produce enough neurotrophins and neurotrophin receptors to repair themselves. Nerve growth factor（NGF） is an important neurotrophin for promoting nerve healing and lysophosphatidylcholine（LPC） has been shown to stimulate NGF receptors（NGFR）. This study tested the administration of a single intraneural injection of LPC（1 mg/mL for single LPC injection and 10 mg/mL for multiple LPC injections） at day 0 and one（day 7）, two（days 5 and 7）, or three（days 5, 7, and 9） injections of NGF（160 ng/mL for single injections and 80 ng/mL for multiple injections） to determine baseline effects on crush ed sciatic nerves in rats. The rats were randomly divided into four groups： control, crush, crush-NGF, and crush-LPC-NGF. The healing of the nerves was measured weekly by monitoring gait; electrophysiological parameters： compound muscle action potential（CMAP） amplitudes; and morphological parameters： total fascicle areas, myelinated fiber counts, fiber densities, fiber packing, and mean g-ratio values at weeks 3 and 6. The crush, crush-NGF, and crush-LPC-NGF groups statistically differed from the control group for all six weeks for the electrophysiological parameters but only differed from the control group at week 3 for the morphological parameters. The crush, crush-NGF, and crush-LPC-NGF groups did not differ from each other over the course of the study. Single injections of LPC and NGF one week apart or multiple treatments of NGF at 5, 7 and 9 days post-injury did not alter the healing rate of the sciatic nerves during weeks 1-6 of the study. These findings are important to define the baseline effects of NGF and LPC injections, as part of a larger effort to determine the minimal dose regimen of NGF to regenerate peripheral nerves.

Biliary phosphatidylcholine and lysophosphatidylcholine profiles in sclerosing cholangitis

AIM:To analyze phospholipid profiles in intrahepatic bile from patients with primary sclerosing cholangitis(PSC)and secondary sclerosing cholangitis(SSC).METHODS:Intrahepatic bile specimens collected via endoscopic retrograde cholangiography from 41 patients were analyzed.Fourteen of these patients were diagnosed with PSC,10 with SSC,11 with choledocholithiasis or no identifiable biliary disease,and 6 with cholangiocellular carcinoma(CCC).Bile acid,cholesterol,protein,and bilirubin contents as well as pancreas lipase activity in bile were determined by biochemical methods.Phosphatidylcholine(PC)and lysophosphatidylcholine(LPC)species were quantified using nanoelectrospray ionization tandem mass spectrometry.RESULTS:Bile from all the examined patient groups showed a remarkably similar PC and LPC species composition,with only minor statistical differences.Total biliary PC concentrations were highest in controls(8030±1843 mol/L)and lowest in patients with CCC(1969±981 mol/L)(P=0.005,controls vs SSC and CCC,respectively,P<0.05).LPC contents in bile were overall low(4.2%±1.8%).Biliary LPC/PC ratios and ratios of biliary PC to bilirubin,PC to cholesterol,PC to protein,and PC to bile acids showed no intergroup differences.CONCLUSION:PC and LPC profiles being similar in patients with or without sclerosing cholangitis,these phospholipids are likely not of major pathogenetic importance in this disease group.

Interaction of major facilitator superfamily domain containing 2A with the blood-brain barrier

The functional and structural integrity of the blood-brain barrier is crucial in maintaining homeostasis in the brain microenvironment;however,the molecular mechanisms underlying the formation and function of the blood-brain barrier remain poorly understood.The major facilitator superfamily domain containing 2A has been identified as a key regulator of blood-brain barrier function.It plays a critical role in promoting and maintaining the formation and functional stability of the blood-brain barrier,in addition to the transport of lipids,such as docosahexaenoic acid,across the blood-brain barrier.Furthermore,an increasing number of studies have suggested that major facilitator superfamily domain containing 2A is involved in the molecular mechanisms of blood-brain barrier dysfunction in a variety of neurological diseases;however,little is known regarding the mechanisms by which major facilitator superfamily domain containing 2A affects the blood-brain barrier.This paper provides a comprehensive and systematic review of the close relationship between major facilitator superfamily domain containing 2A proteins and the blood-brain barrier,including their basic structures and functions,cross-linking between major facilitator superfamily domain containing 2A and the blood-brain barrier,and the in-depth studies on lipid transport and the regulation of blood-brain barrier permeability.This comprehensive systematic review contributes to an in-depth understanding of the important role of major facilitator superfamily domain containing 2A proteins in maintaining the structure and function of the blood-brain barrier and the research progress to date.This will not only help to elucidate the pathogenesis of neurological diseases,improve the accuracy of laboratory diagnosis,and optimize clinical treatment strategies,but it may also play an important role in prognostic monitoring.In addition,the effects of major facilitator superfamily domain containing 2A on blood-brain barrier leakage in various diseases and the research progress on cross-blood-brain barrier drug delivery are summarized.This review may contribute to the development of new approaches for the treatment of neurological diseases.

Effect of lysophosphatidylcholine on behavior and structure of phosphatidylcholine liposomes

Differential scanning calorimetry (DSC), fluorescence polarization and X-ray diffraction were per-formed to investigate the kinetics of the micellar to the lamellar phase transition of dipalmitoylphosphatidylcholine/1-palmitoylphosphatidylcholine (16:0 LPC/DPPC) liposomes at gel phase. With a 16:0 LPC concentration up to 27 mol% only the sharp main transition with relatively high enthalpy (△H) values of DPPC was observed. Increasing 16 : 0 LPC concentration, the phase transition was broadened and the transition enthalpy was decreased and finally totally disappeared. The fluorescence probes of 3AS, 9AS, 12AS, and 16AP were employed, respectively, to detect the mo-bility of various sites of carbon chains of DPPC or 16:0 LPC/DPPC liposomes. It was shown that DPPC liposomes formed in the absence of 16:0 LPC always had a fluidity gradient in both gel and liquid-crystalline phase, while in the presence of 14.1 mol% and 27.0 mol% 16:0 LPC in the mixtures, the fluidity gradient tended to disappear below 40℃: . In the case of 27.0 mol% 16:0 LPC in the 16:0 LPC/DPPC mixtures the polarization of the sixteenth carbon of acyl chains was similar to that of the sixth at l0℃ . Small-angle X-ray diffraction showed that when increasing 16:0 LPC concentration there was a significant decrease in the 16:0 LPC/DPPC liposome thickness. Thickness of the lipid layer of DPPC was 7.30 nm, but those of the samples containing 14.1 mol% and 27.0 mol% of 16:0 LPC were re-duced to 6.79 and 5.52 nm at 25℃ , respectively. Wide-angle X-ray diffraction showed that a reflection appeared at 0. 42 nm with a broad shoulder around 0. 41 nm in pure DPPC at a lipid concentration of 300 mg/mL at 25℃ . In the 16;0 LPC/DPPC system, a single sharp reflection appeared at 0.41 nm. It can be concluded that DPPC forms an in-terdigitated gel phase in the presence of 16:0 LPC concentration below 30 mol%, above this concentration micelliza-tion of the bilayers occurs. The interdigitated structures were destabilized slowly with 16:0 LPC concentration increas-ing, and finally the 16:0 LPC/DPPC bilayers fit into the micelles with its concentration up to 60 mol% .

Lipopolysaccharide triggers nuclear import of Lpcat1 to regulate inducible gene expression in lung epithelia

AIM:To report that Lpcat1 plays an important role in regulating lipopolysaccharide (LPS) inducible gene tran-scription. METHODS:Gene expression in Murine Lung Epithelial MLE-12 cells with LPS treatment or Haemophilus influenza and Escherichia coli infection was analyzed by employing quantitative Reverse Transcription Polymerase Chain Reaction techniques. Nucleofection was used to deliver Lenti-viral system to express or knock down Lpcat1 in MLE cells. Subcellular protein fractionation and Western blotting were utilized to study Lpcat1 nuclear relocation. RESULTS:Lpcat1 translocates into the nucleus from thecytoplasm in murine lung epithelia (MLE) after LPS treatment. Haemophilus influenza and Escherichia coli , two LPS-containing pathogens that cause pneumonia, triggered Lpcat1 nuclear translocation from the cytoplasm. The LPS inducible gene expression profile was determined by quantitative reverse transcription polymerase chain reaction after silencing Lpcat1 or overexpression of the enzyme in MLE cells. We detected that 17 out of a total 38 screened genes were upregulated, 14 genes were suppressed, and 7 genes remained unchanged in LPS treated cells in comparison to controls. Knockdown of Lpcat1 by shRNA dramatically changed the spectrum of the LPS inducible gene transcription, as 18 genes out of 38 genes were upregulated, of which 20 genes were suppressed or unchanged. Notably, in Lpcat1 overex-pressed cells, 25 genes out of 38 genes were reduced in the setting of LPS treatment.CONCLUSION:These observations suggest that Lpcat1 relocates into the nucleus in response to bacterial infection to differentially regulate gene transcriptional repression.

Association between dairy intake,lipids and vascular structure and function in diabetes

AIM To determine lipid species that change in response to a change in dairy consumption. In addition, to investigate whether dairy associated lipid species are correlated with changes in measures of vascular structure and function.METHODS A 12-mo randomised controlled trial was conducted to determine the effect of increased consumption of fruit, vegetables and dairy, compared to usual diet, on measures of vascular structure and function in adults with type 1 and type 2 diabetes(n = 108). Thispaper comprises post-hoc analyses investigating the relationship between dairy intake, serum lipid species and vascular health. Central and peripheral blood pressure, carotid femoral pulse wave velocity, augmentation index, serum lipid species and dietary intake were measured at baseline and 3-mo. Common carotid artery intima media thickness was measured at baseline and 12-mo.RESULTS Serum lipid species [lysophosphatidylcholine(LPC) 14:0, LPC 15:0, LPC 16:1, phosphatidylcholine(PC) 29:0 PC 30:0, PC 31:0 and cholesterol ester(CE) 14:0] were associated with the change in full fat dairy consumption(rho 0.19-0.25; P < 0.05). The 3-mo change in some lipids was positively associated with the 3-mo change in central systolic [LPC 14:0(rho 0.30; P = 0.007), PC 30:0(rho 0.28; P = 0.010)] and diastolic blood pressure [LPC 14:0(rho 0.32; P = 0.004), LPC 15:0(rho 0.23; P = 0.04), LPC 16:1(rho 0.23; P = 0.035), PC 29:0(rho 0.28; P = 0.01), PC 30:0(rho 0.36; P = 0.001), PC 31:0(rho 0.30; P = 0.007)] and 12-mo change in common carotid artery intimal medial thickness [CE 14:0(rho 0.22; P = 0.02)]. Pulse wave velocity and augmentation index were unrelated to dairy and lipid species.CONCLUSION An increase in dairy associated lipids appears to be associated with an increase in blood pressure and common carotid intimal medial thickness.

The Effect of the LysoPC-induced Endothelial Cell Conditioned Medium on Proliferating Cell Nuclear Antigen Expression of the Calf Thoracic Aorta Smooth Muscle Cells

In order to study the effect of and mechanism of lysophosphatidylcholine (LysoPC) on proliferation of the calf thoracic aorta smooth muscle cells (ASMCs), the ASMCs were used to observe the effects of LysoPC induced endothelial cell conditioned medium on the DNA content and proliferating cell nuclear antigen (PCNA) expression in the calf thoracic ASMCs by flow cytometry and Western Blot technique. It was found that LysoPC induced endothelial cell conditioned medium could significantly promote PCNA expression of the calf ASMCs, induce the converting of ASMCs from G 0 /G 1 phase to S phase of DNA synthesis, and increase the tyrosine phosphorylation protein expression. Tyrosine protein kinase inhibitor (TPKi) RG50864 could obviously inhibit proliferation of LysoPC induced ASMCs in a dose dependence manner. The results indicated that the effect of LysoPC promoting the proliferation of ASMCs is partly evoked by endothelial cell derived growth factors such as PDGF and so on.

Effects of ovarian cancer G protein coupled receptor 1 on the proliferation, migration, and adhesion of human ovarian cancer cells

Background OGR1 was found as a G-protein coupled receptor （GPCR） and proton sensor. Our previous studies have found that OGR1 has inhibitory effect on the metastasis of prostate cancer. In order to investigate the roles of OGR1 gene in the biological activities of ovarian cancer, we studied the OGR1 effects on ovarian cancer cells, HEY cells.Methods OGR1 gene was transfected into HEY cell, in which endogenous expression is low. OGR1-overxepressed cells and vector-transfected cells were compared in different assays. Western blotting was employed to confirm the high expression level of OGR1. Cell proliferation was determined by MTT assay and cell doubling time assay. Cell migration assay （transwell assay） and cell adhesion assay were performed to determine the migration and adhesion potential of cells. Student＇s t test was employed for statistical analysis.Results Proliferation of OGR1-overexpressed cells was significantly reduced （P ＜0.01）; cell migration was significantly inhibited in the OGR1-transfected cells （P ＜0.01）; cell adhesion to extracellular matrix including fibronectin, vitronectin,collagen Ⅰ/Ⅳ was significantly increased （P ＜0.01）.Conclusions OGR1 expression in human ovarian cancer cells significantly inhibited the cell proliferation and migration,but significantly enhanced cell adhesion to the extracellular matrix. It indicated that OGR1 may be a tumor suppressor gene for ovarian cancer.

A mechanism underlying stimulation and inhibition of protein kinase C by lyso-PC: A role of membrane physical state

Lysophosphatidylcholine (lyso PC) biphasically regulates the diacylglycerol induced activation of protein kinase C (PKC). In common parlance, lyso PC stimulates PKC at low concentrations, but, conversely, inhibits it at high concentrations. The activity of purified PKC from rat brains was measured in the vesicles made up of dipalmitoylphosphatidylserine (DPPS), 1,2 sn diolein (DOG) and different molar ratios of 1 palmitoyl sn glycerol 3 phosphoryl choline (C16:0 lyso PC). The effect, i.e. stimulation or inhibition on PKC by C16:0 lyso PC, depends on DPPS and DOG concentrations as well as its own concentration. When the concentration of DOG is stable, this C16:0 lyso PC action depends on C16:0 lyso PC/DPPS molar ratio. Differential scanning calorimetry (DSC), two fluorescence probes and light scattering were used to analyze the physical characteristics of membrane, including thermotropic phase behavior, the turbidity, the lipid molecular acyl chains packing and the head group spacing. The more adulteration of C16:0 lyso PC in liposome bilayer membrane, the looser acyl chains pack, and the broader head group spacing. DSC results show that there are two immiscible lipid areas in the membrane: C16:0 lyso PC rich area and C16:0 lyso PC poor area. When C16:0 lyso PC/DPPS molar ratio was 0 234, the two areas had the broadest boundary and the activation of PKC was the highest. When the ratio was over 0 434, the phase transition of DPPS disappeared; micelle tended to substitute the structure of bilayer; the activity of PKC was inhibited completely. DOG can stabilize the bilayer structure of membrane, so the C16:0 lyso PC/DPPS molar ratios to inhibit PKC in lipid mixture with DOG are higher than that without DOG. The ability of C16:0 lyso PC to change the physical properties and the structure of membrane plays an important role in its effect on PKC activation.

Deciphering lipid dysregulation in ALS:from mechanisms to translational medicine

Lipids,defined by low solubility in water and high solubility in nonpolar solvents,can be classified into fatty acids,glycerolipids,glycerophospholipids,sphingolipids,and sterols.Lipids not only regulate integrity and fluidity of biologi-cal membranes,but also serve as energy storage and bioactive molecules for signaling.Causal mutations in SPTLC1(serine palmitoyltransferase long chain subunit 1)gene within the lipogenic pathway have been identified in amyo-trophic lateral sclerosis(ALS),a paralytic and fatal motor neuron disease.Furthermore,lipid dysmetabolism within the central nervous system and circulation is associated with ALS.Here,we aim to delineate the diverse roles of different lipid classes and understand how lipid dysmetabolism may contribute to ALS pathogenesis.Among the different lipids,accumulation of ceramides,arachidonic acid,and lysophosphatidylcholine is commonly emerging as detri-mental to motor neurons.We end with exploring the potential ALS therapeutics by reducing these toxic lipids.