Sphingosine-1-phosphate (S1P) is the main metabolite produced in the process of phospholipid metabolism, which can promote proliferation, migration, and apoptosis of cells, and maintain the barrier function of vascular endothelium. The latest researches showed that S1P can alleviate acute lung injury (ALI) and the inflammation caused by ALI, while the dosage of S1P is still needed to be considered. Mesenchymal stem cells (MSCs) have been a emerging therapy with potential therapeutic effects on ALI because of their characteristics of self-replication and multi-directional differentiation, and their advantages in hematopoiesis, immune regulation, and tissue repair. S1P can promote differentiation of MSCs and participate in immune regulation, while MSCs can regulate the homeostasis of S1P in the body. The synergistic effect of S1P and MSC provides a new treatment method for ALI. This article reviews the production and biological function of S1P, receptor and signal pathway of S1P, the therapeutic effects of S1P on ALI, and the research advances of S1P combined with MSCs in the treatment of ALI, aiming to provide theoretical references for the development of S1P targeted drugs in the treatment of ALI and the search for new combined treatment schemes for ALI.
Acute Lung Injury ; Animals ; Lung/metabolism* ; Lysophospholipids/pharmacology* ; Mice ; Mice, Inbred C57BL ; Sphingosine/pharmacology*

The aim of the present study was to explore the role of orphan G protein-coupled receptor 55 (GPR55) in diabetic gastroparesis (DG). Streptozotocin (STZ) was used to mimic the DG model, and the body weight and blood glucose concentration were tested 4 weeks after STZ injection (i.p.). Electrogastrogram and phenolsulfonphthalein test were used for detecting gastric emptying. Motilin (MTL), gastrin (GAS), vasoactive intestinal peptide (VIP), and somatostatin (SS) levels in plasma were determined using radioimmunology. Real-time PCR and Western blot were applied to identify the expression of GPR55 in gastric tissue, and immunohistochemistry was used to detect the distribution. The effect of lysophosphatidylinositol (LPI), an agonist of GPR55, was observed. STZ mice showed increased blood glucose concentration, lower body weight, decreased amplitude of slow wave, and delayed gastric emptying. LPI antagonized these effects of STZ. Compared to the control group, STZ caused significant decreases of MTL and GAS levels (P < 0.01), as well as increases of SS and VIP levels (P < 0.01). The changes of these hormones induced by STZ were counteracted when using LPI. GPR55 located in mice stomach, and it was up-regulated in DG. Although LPI showed no effects on the distribution and expression of GPR55 in normal mice, it could inhibit STZ-induced GPR55 up-regulation. These results suggest GPR55 is involved in the regulation of gastric movement of DG, and may serve as a new target of DG treatment. LPI, an agonist of GPR55, can protect against STZ-induced DG, and the mechanism may involve the change of GPR55 expression and modification of gastrointestinal movement regulating hormones.
Animals ; Diabetes Mellitus, Experimental ; metabolism ; pathology ; Gastroparesis ; metabolism ; pathology ; Lysophospholipids ; pharmacology ; Mice ; Receptors, Cannabinoid ; metabolism

OBJECTIVETo investigate the effect and potential mechanism of lysophosphatidic acid (LPA) and antiarrhythmic peptide (AAP10) on rabbit ventricular arrhythmia.

METHODSTwenty-four rabbits were randomly divided into three groups (n = 8 each): control group, LPA group and AAP10 + LPA group. Using arterially perfused rabbit ventricular wedge preparations, transmural ECG and action potentials from both endocardium and epicardium were simultaneously recorded in the whole process of all experiments with two separate floating microeletrodes. The incidence of ventricular arrhythmia post S1S2 stimulation was recorded. Protein levels of nonphosphorylated Cx43 and total Cx43 were evaluated by Western blot. The distribution of nonphosphorylated Cx43 was observed by confocal immunofluorescence microscopy.

RESULTSCompared with the control group, the QT interval, endocardial action potential duration, transmural repolarization dispersion (TDR) and incidence of ventricular arrhythmia were significantly increased and nonphosphorylated Cx43 expression was significantly upregulated in the LPA group. Compared with the LPA group, cotreatment with AAP10 can reduce the QT interval, endocardial action potential duration, TDR and incidence of ventricular arrhythmia (25.0% vs 62.5%, P < 0.01) and downregulate nonphosphorylated Cx43.

CONCLUSIONSLPA could promote the arrhythmia possibly by upregulating nonphosphorylated Cx43 and subsequent gap junction transmission inhibition. Gap junction enhancer AAP10 could attenuate the pro-arrhythmic effect of LPA probably by downregulating myocardial nonphosphorylated Cx43 expression.

Animals ; Anti-Arrhythmia Agents ; pharmacology ; Arrhythmias, Cardiac ; chemically induced ; metabolism ; physiopathology ; Connexin 43 ; metabolism ; Lysophospholipids ; adverse effects ; Oligopeptides ; pharmacology ; Rabbits

Action Potentials ; drug effects ; physiology ; Animals ; Guinea Pigs ; Heart Ventricles ; drug effects ; Lysophospholipids ; pharmacology ; Myocardial Contraction ; drug effects ; physiology ; Myocardium ; Sphingosine ; analogs & derivatives ; pharmacology

This study examined whether propofol and aminophylline affect the mobilization of intracellular calcium in human umbilical vein endothelial cells. Intracellular calcium was measured using laser scanning confocal microscopy. Cultured and serum-starved cells on round coverslips were incubated with propofol or aminophylline for 30 min, and then stimulated with lysophosphatidic acid, propofol and aminophylline. The results were expressed as relative fluorescence intensity and fold stimulation. Propofol decreased the concentration of intracellular calcium, whereas aminophylline caused increased mobilization of intracellular calcium in a concentration-dependent manner. Propofol suppressed the lysophosphatidic acid-induced mobilization of intracellular calcium in a concentration-dependent manner. Propofol further prevented the aminophylline-induced increase of intracellular calcium at clinically relevant concentrations. However, aminophylline reversed the inhibitory effect of propofol on the elevation of intracellular calcium by lysophosphatidic acid. Our results suggest that propofol and aminophylline antagonize each other on the mobilization of intracellular calcium in human umbilical vein endothelial cells at clinically relevant concentrations. Serious consideration should be given to how this interaction affects mobilization of intracellular calcium when these two drugs are used together.
Aminophylline/*antagonists & inhibitors/pharmacology ; Anesthetics, Intravenous/*antagonists & inhibitors/pharmacology ; Bronchodilator Agents/*antagonists & inhibitors/pharmacology ; Calcium/*metabolism ; Cells, Cultured ; Endothelial Cells/*drug effects/metabolism ; Endothelium, Vascular/cytology ; Humans ; Lysophospholipids/pharmacology ; Microscopy, Confocal ; Propofol/*antagonists & inhibitors/pharmacology ; Umbilical Veins/cytology

Animals ; Arrhythmias, Cardiac ; chemically induced ; etiology ; Female ; Heart ; drug effects ; In Vitro Techniques ; Lysophospholipids ; pharmacology ; physiology ; Male ; Random Allocation ; Rats ; Rats, Wistar

Effects of lysophosphatidic acid (LPA), an extracellular phospholipid signal, on the proliferation of rat embryonic neural stem cells (NSCs) and their differentiation into microtubule-associated protein 2 (MAP2)-positive and choline acetyltransferase (ChAT)-positive, i.e. cholinergic-committed neurons, were observed in vitro by [(3)H]-thymidine incorporation, immunocytochemistry, Western blot and other techniques. The results showed that: (1) Lower concentrations of LPA (0.01~1.0 mumol/L) dose-dependently enhanced the uptake of [(3)H]-thymidine by NSCs cultured in specific serum-free medium, indicating a significant promotive action of LPA on the proliferation of NSCs. (2) After fetal bovine serum which induces and commences the differentiation of NSCs, was used in the medium, the lower concentrations of LPA increased the percentages of both MAP2- and ChAT-immunoreactive neurons, with a peak at 0.1 mumol/L LPA in two cases. (3) The promotive effects of LPA on the differentiation of MAP2- and ChAT-positive neurons were also supported by the up-regulation of the expressions of both MAP2 and ChAT proteins detected by Western blot. (4) At the early phase of differentiation of NSCs, the cell migration and neurite extension were enhanced significantly by lower dosages of LPA under phase-contrast microscope. These results suggest that LPA within certain lower range of concentrations promotes the proliferation of NSCs and their differentiation into unspecific MAP2-positive and specific cholinergic-committed neurons, and also strengthens the migration and neurite extension of the newly-generated neuronal (and also glial as reported elsewhere) progenitors.
Animals ; Cell Differentiation ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Cholinergic Neurons ; cytology ; Embryonic Stem Cells ; drug effects ; Lysophospholipids ; pharmacology ; Neural Stem Cells ; drug effects ; Rats

The effect of lysophosphatidic acid (LPA), with a wide range of its different concentrations, upon cultured mouse cortical neurons was assessed by electrophoresis of DNA fragments, HO33342 and TUNEL stainings, and also by ultrastructural examination at times. The results showed that administration of LPA at lower concentrations (0.1-30 micromol/L) dose-dependently protected cortical neurons from apoptosis that was induced by deprivation of serum from the cultural medium, while 50 micromol/L or higher concentrations of LPA failed to show this effect; and moreover, the concentrations higher than 50 micromol/L induced apoptosis in neurons cultured in serum-containing complete medium. These results suggest that a moderate concentration of LPA may play as a survival factor in apoptotic cortical neurons, while an excessive level of LPA induces apoptosis in neurons cultured in complete medium.
Animals ; Animals, Newborn ; Apoptosis ; drug effects ; Cell Survival ; drug effects ; Cells, Cultured ; Cerebral Cortex ; cytology ; Culture Media, Serum-Free ; Lysophospholipids ; pharmacology ; Mice ; Neurons ; cytology

To study the effect of lysophosphatidic acid (LPA) on the differentiation of embryonic neural stem cells (NSCs) into neuroglial cells in rats in vitro, both oligodendrocytes and astrocytes were detected by their marker proteins galactocerebroside (Gal-C) and glial fibrillary acidic protein (GFAP), respectively, using double-labeling immunocytochemistry. RT-PCR assay was also used for analyzing the expression of LPA receptors in NSCs. Our results showed that: (1) LPA at different concentrations (0.01-3.0 mumol/L) was added to culture medium and cell counting was carried out on the 7th day in all groups. Exposure to LPA led to a dose-dependent increase of oligodendrocytes with the response peaked at 1.0 mumol/L, with an increased percentage of 32.6% (P<0.01) of total cells as compared to that of 8.5% in the vehicle group. (2) LPA showed no effect on the differentiation of NSCs into astrocytes. (3) RT-PCR assay showed that LPA(1) and LPA(3) receptors were strongly expressed while LPA(2) receptor expressed weakly in NSCs. These results suggest that LPA at low concentration might act as an extracellular signal through the receptors in NSCs, mainly LPA(1) and LPA(3) receptors, to promote the differentiation of NSCs into oligodendrocytes, while it exhibits little, if any, conceivable effect on the differentiation of NSCs into astrocytes.
Animals ; Cell Differentiation ; drug effects ; Cells, Cultured ; Lysophospholipids ; pharmacology ; Neural Stem Cells ; cytology ; drug effects ; Neuroglia ; cytology ; Rats ; Receptors, Lysophosphatidic Acid ; metabolism

Recently, a mitochondrial ceramidase has been identified and cloned, whose mitochondrial localization strongly suggests the existence of an unexpected mitochondrial pathway of ceramide metabolism that may play a key role in mitochondrial functions, especially in the regulation of apoptosis. To explore the biological effect of mitochondrial ceramidase on cells, pcDNA 3.1/His-CDase plasmid, containing mitochondrial ceramidase cDNA sequence, was transducted into K562 cells mediated by liposome, and G418 was used to screen for positive colonies. A stable transfected K562 cell line was established and named as 'K562TC'. The difference between K562 and K562TC cells in chemotheraputic cytotoxicity response and serum-withdrawal resistance and Bcl-2 protein expression were evaluated by MTT assay, annexin V/PI test, flow cytometry or Western blotting, respectively. The results showed that although survival was comparable between K562 and K562TC cells after exposed to adriamycin, etoposide or arsenious acid, K562TC cells with elevated Bcl-2 protein expression level as identified by FCM or Western blotting revealed stronger resistance to apoptosis induced by serum withdrawal than their parental cells. Inhibition of mitochondrial ceramidase expression in K562TC cells by its specific antisense oligodeoxynucleotide was correlated with a decrease in Bcl-2 protein level. N, N-dimethylsphingosine, a sphingosine kinase inhibitor, depleted intracellular sphingosine-1-phosphate production, also abrogated Bcl-2 protein expression in K562TC cells, while Bcl-2 protein level in K562 cells was up-regulated by exogenous sphingosine-1-phosphate. It is concluded that mitochondrial ceramidase overexpression in K562 cells leads to markedly elevated level of Bcl-2 protein and results in more resistance to serum withdrawal. This effect is initiated not by sphingosine, the direct metabolite of mitochondrial ceramidase, but via sphingosine-1-phosphate, its phosphorylated form. This is the first evidence that mitochondrial ceramidase, through its sphingoid metabolite sphingosine-1-phosphate, up-regulates Bcl-2 protein expression in K562 cells.
Amidohydrolases ; physiology ; Apoptosis ; Arsenites ; pharmacology ; Ceramidases ; Doxorubicin ; pharmacology ; Etoposide ; pharmacology ; Humans ; K562 Cells ; Lysophospholipids ; physiology ; Mitochondria ; enzymology ; Oligonucleotides, Antisense ; pharmacology ; Proto-Oncogene Proteins c-bcl-2 ; analysis ; Sphingosine ; analogs & derivatives ; physiology ; Up-Regulation