brp-lpa and lysophosphatidic-acid

Microglia, the immunocompetent cells of the CNS, rapidly respond to brain injury and disease by altering their morphology and phenotype to adopt an activated state. Microglia can exist broadly between two different states, namely the classical (M1) and the alternative (M2) phenotype. The first is characterized by the production of pro-inflammatory cytokines/chemokines and reactive oxygen and/or nitrogen species. In contrast, alternatively activated microglia are typified by an anti-inflammatory phenotype supporting wound healing and debris clearance. The objective of the present study was to determine the outcome of lysophosphatidic acid (LPA)-mediated signaling events on microglia polarization.. LPA receptor expression and cyto-/chemokine mRNA levels in BV-2 and primary murine microglia (PMM) were determined by qPCR. M1/M2 marker expression was analyzed by Western blotting, immunofluorescence microscopy, or flow cytometry. Cyto-/chemokine secretion was quantitated by ELISA.. BV-2 cells express LPA receptor 2 (LPA2), 3, 5, and 6, whereas PMM express LPA1, 2, 4, 5, and 6. We show that LPA treatment of BV-2 and PMM leads to a shift towards a pro-inflammatory M1-like phenotype. LPA treatment increased CD40 and CD86 (M1 markers) and reduced CD206 (M2 marker) expression. LPA increased inducible nitric oxide synthase (iNOS) and COX-2 levels (both M1), while the M2 marker Arginase-1 was suppressed in BV-2 cells. Immunofluorescence studies (iNOS, COX-2, Arginase-1, and RELMα) extended these findings to PMM. Upregulation of M1 markers in BV-2 and PMM was accompanied by increased cyto-/chemokine transcription and secretion (IL-1β, TNFα, IL-6, CCL5, and CXCL2). The pharmacological LPA5 antagonist TCLPA5 blunted most of these pro-inflammatory responses.. LPA drives BV-2 and PMM towards a pro-inflammatory M1-like phenotype. Suppression by TCLPA5 indicates that the LPA/LPA5 signaling axis could represent a potential pharmacological target to interfere with microglia polarization in disease.

Topics: Actins; Analysis of Variance; Animals; Animals, Newborn; Cell Polarity; Cells, Cultured; Cerebral Cortex; Cytokines; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Lysophospholipids; Mice; Microglia; Nitric Oxide Synthase Type II; Reactive Oxygen Species; Receptors, Lysophosphatidic Acid; RNA, Messenger; Time Factors

Hyperoxia is still broadly used in clinical practice in order to assure organ oxygenation in critically ill patients, albeit known toxic effects. In this present study, we hypothesize that lysophosphatidic acid (LPA) mediates NKT cell activation in a mouse model of hyperoxic lung injury. In vitro, pulmonary NKT cells were exposed to hyperoxia for 72 h, and the induction of the ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP-2) was examined and production of lysophosphatidic acid (LPA) was measured. In vivo, animals were exposed to 100 % oxygen for 72 h and lungs and serum were harvested. Pulmonary NKT cells were then incubated with the LPA antagonist Brp-LPA. Animals received BrP-LPA prior to oxygen exposure. Autotaxin (ATX, ENPP-2) was significantly up-regulated on pulmonary NKT cells after hyperoxia (p < 0.01) in vitro. LPA levels were increased in supernatants of hyperoxia-exposed pulmonary NKT cells. LPA levels were significantly reduced by incubating NKT cells with LPA-BrP during oxygen exposure (p < 0,05) in vitro. Hyperoxia-exposed animals showed significantly increased serum levels of LPA (p ≤ 0,05) as well as increased pulmonary NKT cell numbers in vivo. BrP-LPA injection significantly improved survival as well as significantly decreased lung injury and lowered pulmonary NKT cell numbers. We conclude that NKT cell-induced hyperoxic lung injury is mediated by pro-inflammatory LPA generation, at least in part, secondary to ENPP-2 up-regulation on pulmonary NKT cells. Being a potent LPA antagonist, BrP-LPA prevents hyperoxia-induced lung injury in vitro and in vivo.

Topics: Acute Lung Injury; Animals; Cell Count; Hyperoxia; Inflammation; Lung; Lysophosphatidylcholines; Lysophospholipids; Mice; Mice, Inbred C57BL; Natural Killer T-Cells; Oxygen; Phosphoric Diester Hydrolases; Receptors, Purinergic P2X7; Up-Regulation

Lysophosphatidic acid (LPA) is a potent bioactive lipid mediator with diverse biological properties. We previously found altered expression of the LPA-related genes in rodents after treatment with sertraline, which is widely used to treat anxiety disorders and depression. However, little is known about the behavioral effects of LPA. In the present study, we investigated the behavioral effects of intracerebroventricular injection of LPA in adult mice. LPA did not significantly affect spontaneous locomotor activity, suggesting that LPA does not induce hyperactivity, ataxia, or sedation. We next investigated the emotional effects of LPA via the hole-board test. LPA significantly increased the number of head-dips in a dose- and time-related manner. A significant induction of head-dip counts occurred 15 and 30 min after LPA administration. To clarify the involvement of LPA receptors, we examined the effect of the non-selective LPA1-4 receptor antagonist, 1-bromo-3(S)-hydroxy-4-(palmitoyloxy)butyl-phosphonate (BrP-LPA) co-administered with LPA. BrP-LPA dose-dependently inhibited LPA-induced head-dip counts. We next investigated anxiety-like behavior via the elevated plus-maze test. LPA significantly reduced the percentage of time spent in the open arms and BrP-LPA dose-dependently inhibited this anxiety-like behavior. In conclusion, LPA induced anxiety-like behavior in mice via LPA receptors. Our results suggest that LPA signaling plays an important role in regulating anxiety in mice.

Topics: Analysis of Variance; Animals; Anxiety; Disease Models, Animal; Dose-Response Relationship, Drug; Exploratory Behavior; Lysophospholipids; Male; Maze Learning; Mice; Mice, Inbred C57BL; Motor Activity; Reaction Time; Receptors, Lysophosphatidic Acid; Time Factors

Autotaxin (ATX) is a secreted glycoprotein with the lysophospholipase D (lysoPLD) activity to convert lysophosphatidylcholine (LPC) into lysophosphatidic acid (LPA), a bioactive lysophospholipid involved in diverse biological actions. ATX is highly expressed in some cancer cells and contributes to their tumorigenesis, invasion, and metastases, while in other cancer cells ATX is silenced or expressed at low level. The mechanism of ATX expression regulation in cancer cells remains largely unknown.. In the present study, we demonstrated that trichostatin A (TSA), a well-known HDAC inhibitor (HDACi), significantly induced ATX expression in SW480 and several other cancer cells with low or undetectable endogenous ATX expression. ATX induction could be observed when HDAC3 and HDAC7 were down-regulated by their siRNAs. It was found that HDAC7 expression levels were low in the cancer cells with high endogenous ATX expression. Exogenous over-expression of HDAC7 inhibited ATX expression in these cells in a HDAC3-dependent manner. These data indicate that HDAC3 and HDAC7 collaboratively suppress ATX expression in cancer cells, and suggest that TSA induce ATX expression by inhibiting HDAC3 and HDAC7. The biological significance of this regulation mechanism was revealed by demonstrating that TSA-induced ATX protected cancer cells against TSA-induced apoptosis by producing LPA through its lysoPLD activity, which could be reversed by BrP-LPA and S32826, the inhibitors of the ATX-LPA axis.. We have demonstrated that ATX expression is repressed by HDAC3 and HDAC7 in cancer cells. During TSA treatment, ATX is induced due to the HDAC3 and HDAC7 inhibition and functionally antagonizes the TSA-induced apoptosis. These results reveal an internal HDACi-resistant mechanism in cancer cells, and suggest that the inhibition of ATX-LPA axis would be helpful to improve the efficacy of HDACi-based therapeutics against cancer.

Topics: Acetylation; Anilides; Apoptosis; Cell Line, Tumor; Cytoprotection; Down-Regulation; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; Histone Deacetylase Inhibitors; Histone Deacetylases; Humans; Hydroxamic Acids; Lysophospholipids; Multienzyme Complexes; Organophosphonates; Phosphodiesterase I; Phosphoric Diester Hydrolases; Promoter Regions, Genetic; Pyrophosphatases; Receptors, Lysophosphatidic Acid; RNA, Messenger; Signal Transduction; Up-Regulation

Signal transduction modifiers that modulate the lysophosphatidic acid (LPA) pathway have potential as anticancer agents. Herein, we describe metabolically stabilized LPA analogues that reduce cell migration and invasion and cause regression of orthotopic breast tumors in vivo. Two diastereoisomeric alpha-bromophosphonates (BrP-LPA) were synthesized, and the pharmacology was determined for five LPA G protein-coupled receptors (GPCRs). The syn and anti diastereomers of BrP-LPA are pan-LPA GPCR antagonists and are also nanomolar inhibitors of the lysophospholipase D activity of autotaxin, the dominant biosynthetic source of LPA. Computational models correctly predicted the diastereoselectivity of antagonism for three GPCR isoforms. The anti isomer of BrP-LPA was more effective than syn isomer in reducing migration of MDA-MB-231 cells, and the anti isomer was superior in reducing invasion of these cells. Finally, orthotopic breast cancer xenografts were established in nude mice by injection of MB-231 cells in an in situ cross-linkable extracellular matrix. After 2 weeks, mice were treated with the BrP-LPA alone (10 mg/kg), Taxol alone (10 mg/kg), or Taxol followed by BrP-LPA. All treatments significantly reduced tumor burden, and BrP-LPA was superior to Taxol in reducing blood vessel density in tumors. Moreover, both the anti- and syn-BrP-LPA significantly reduced tumors at 3 mg/kg.

Topics: Breast Neoplasms; Cell Line, Tumor; Cell Movement; Female; Humans; Lysophospholipids; Multienzyme Complexes; Organophosphonates; Phosphodiesterase I; Phosphoric Diester Hydrolases; Pyrophosphatases; Receptors, Lysophosphatidic Acid