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Lysophosphatidate (LPA) and sphingosine 1-phosphate (S1P) promote vasculogenesis, angiogenesis, and wound healing by activating a plethora of overlapping signaling pathways that stimulate mitogenesis, cell survival, and migration. As such, maladaptive signaling by LPA and S1P have major effects in increasing tumor progression and producing poor patient outcomes after chemotherapy and radiotherapy. Many signaling actions of S1P and LPA are not redundant; each are vital in normal physiology and their metabolisms differ. In the present work, we studied how LPA signaling impacts S1P metabolism and signaling in MDA-MB-231 and MCF-7 breast cancer cells. LPA increased sphingosine kinase-1 (SphK1) synthesis and rapidly activated cytosolic SphK1 through association with membranes. Blocking phospholipase D activity attenuated the LPA-induced activation of SphK1 and the synthesis of ABCC1 and ABCG2 transporters that secrete S1P from cells. This effect was magnified in doxorubicin-resistant MCF-7 cells. LPA also facilitated S1P signaling by increasing mRNA expression for S1P1 receptors. Doxorubicin-resistant MCF-7 cells had increased S1P2 and S1P3 receptor expression and show increased LPA-induced SphK1 activation, increased expression of ABCC1, ABCG2 and greater S1P secretion. Thus, LPA itself and LPA-induced S1P signaling counteract doxorubicin-induced death of MCF-7 cells. We conclude from the present and previous studies that LPA promotes S1P metabolism and signaling to coordinately increase tumor growth and metastasis and decrease the effectiveness of chemotherapy and radiotherapy for breast cancer treatment.

Lysophosphatidic acid (LPA) is a versatile lysolipid, and activates a variety of signaling cascades in many cell types. Extracellular LPA is produced from lysophosphatidylcholine (LPC) by the enzyme autotaxin (ATX), and binds to a family of G-protein coupled receptors on its target cells. Research by many groups continues to support the idea that LPA, and the ATX-LPA axis, have important roles in asthma and allergic airway inflammation. In vitro studies have shown that LPA activates many cell types implicated in airway inflammation, including eosinophils, mast cells, dendritic cells, lymphocytes, airway epithelial cells, and airway smooth muscle cells. In animal models ATX and LPA receptor antagonists have been shown to attenuate allergic airway inflammation and hyperreactivity, cardinal features of asthma in humans. ATX and LPA antagonists are currently under active development to treat lung fibrosis, cancer, and other conditions. If compounds with acceptable safety profiles can be identified, then it seems likely that they will be useful in inflammatory lung diseases like asthma.

Background Lysophosphatidic acid (LPA) is involved in numerous biological processes, including neurodevelopment, chronic inflammation, and immunologic response in the central nervous system. Autotaxin (ATX) is a secreted enzyme that produces LPA from lysophosphatidylcholine (LPC). Previous studies have demonstrated decreased protein levels of ATX in cerebrospinal fluid (CSF) of patients with major depressive disorder (MDD). Based on those studies, the current study investigated the levels of lysophospholipids species including LPA and related metabolic enzymes, in CSF of patients with MDD and schizophrenia (SCZ). Methods The levels of lysophospholipids species and related metabolic enzymes were measured with either liquid chromatography-tandem mass spectrometry or enzyme-linked immunosorbent assay. Japanese patients were diagnosed with DSM-IV-TR. CSF was obtained from age- and sex-matched healthy controls (n = 27) and patients with MDD (n = 26) and SCZ (n = 27). Results Of all lysophospholipids species, the levels of LPA 22:6 (LPA - docosahexaenoic acid) were significantly lower in patients with MDD and SCZ than in healthy controls. These levels were negatively correlated with several clinical symptomatic scores of MDD, but not those of SCZ. In addition, the levels of LPA 22:6 were significantly correlated with the levels of LPC 22:6 among all 3 groups. On the other hand, the levels of LPA 22:6 were not correlated with ATX activity in patients with MDD and SCZ. Conclusion The lower levels of LPA 22:6 in patients with MDD and SCZ suggest an abnormality of LPA 22:6 metabolism. In addition, several depressive symptoms in patients with MDD were significantly associated with the lower levels of LPA 22:6, suggesting an involvement of LPA 22:6 in the pathophysiology of MDD.

Muscular dystrophies (MDs) are a diverse group of severe disorders characterized by increased skeletal muscle feebleness. In many cases, respiratory and cardiac muscles are also compromised. Skeletal muscle inflammation and fibrosis are hallmarks of several skeletal muscle diseases, including MDs. Until now, several keys signaling pathways and factors that regulate inflammation and fibrosis have been identified. However, no curative treatments are available. Therefore, it is necessary to find new therapeutic targets to fight these diseases and improve muscle performance. Lysophosphatidic acid (LPA) is an active glycerophospholipid mainly synthesized by the secreted enzyme autotaxin (ATX), which activates six different G protein-coupled receptors named LPA1 to LPA6 (LPARs). In conjunction, they are part of the ATX/LPA/LPARs axis, involved in the inflammatory and fibrotic response in several organs-tissues. This review recapitulates the most relevant aspects of inflammation and fibrosis in MDs. It analyzes experimental evidence of the effects of the ATX/LPA/LPARs axis on inflammatory and fibrotic responses. Finally, we speculate about its potential role as a new therapeutic pharmacological target to treat these diseases.

Lysophosphatidic acid (LPA) and its G-protein-coupled receptors (Lpar1–Lpar6) mediate a plethora of activities associated with cancer growth and progression. However, there is no systematic study about whether and how LPA promotes esophageal squamous cell carcinoma (ESCC). Here, we show that autotaxin (ATX), a primary LPA-producing enzyme, is highly expressed in ESCC, and overexpressed ATX is associated with the poor outcome of ESCC patients. Meanwhile, the expression of Lpar1 was much higher in ESCC cells compared with Het-1a (human esophagus normal epithelial cells). Functional experiments showed that LPA remarkably increased the proliferation and migration of ESCC cells. Furthermore, Lpar1 knockdown abolished the effect of LPA on ESCC cell proliferation and migration. Mechanistic studies revealed that LPA promoted ESCC cell lines proliferation and migration through PI3K/Akt pathway. Treatment of KYSE30 cell xenografts with Lpar1 inhibitor BMS-986020 significantly repressed tumor growth. Our results shed light on the important role of LPA in ESCC, and Lpar1 might be a potential treatment target for ESCC.

Objective Acute myocardial infarction (AMI) initiates pathological inflammation which aggravates tissue damage and causes heart failure. Lysophosphatidic acid (LPA), produced by autotaxin (ATX), promotes inflammation and the development of atherosclerosis. The role of ATX/LPA signaling nexus in cardiac inflammation and resulting adverse cardiac remodeling is poorly understood. Approach and results We assessed autotaxin activity and LPA levels in relation to cardiac and systemic inflammation in AMI patients and C57BL/6 (WT) mice. Human and murine peripheral blood and cardiac tissue samples showed elevated levels of ATX activity, LPA, and inflammatory cells following AMI and there was strong correlation between LPA levels and circulating inflammatory cells. In a gain of function model, lipid phosphate phosphatase-3 (LPP3) specific inducible knock out (Mx1-Plpp3Δ) showed higher systemic and cardiac inflammation after AMI compared to littermate controls (Mx1-Plpp3fl/fl); and a corresponding increase in bone marrow progenitor cell count and proliferation. Moreover, in Mx1- Plpp3Δ mice, cardiac functional recovery was reduced with corresponding increases in adverse cardiac remodeling and scar size (as assessed by echocardiography and Masson's Trichrome staining). To examine the effect of ATX/LPA nexus inhibition, we treated WT mice with the specific pharmacological inhibitor, PF8380, twice a day for 7 days post AMI. Inhibition of the ATX/LPA signaling nexus resulted in significant reduction in post-AMI inflammatory response, leading to favorable cardiac functional recovery, reduced scar size and enhanced angiogenesis. Conclusion ATX/LPA signaling nexus plays an important role in modulating inflammation after AMI and targeting this mechanism represents a novel therapeutic target for patients presenting with acute myocardial injury.

Peritoneal dissemination and malignant ascites in pancreatic ductal adenocarcinoma (PDAC) patients represent a major clinical issue. Lysophosphatidic acid (LPA) is a lipid mediator that modulates the progression of various cancers. Based on the increasing evidence showing that LPA is abundant in malignant ascites, we focused on autotaxin (ATX), which is a secreted enzyme that is important for the production of LPA. This study aimed to elucidate the importance of the ATX‐LPA axis in malignant ascites in PDAC and to determine whether ATX works as a molecular target for treating peritoneal dissemination. In a PDAC peritoneal dissemination mouse model, the amount of ATX was significantly higher in ascites than in serum. An in vitro study using two PDAC cell lines, AsPC‐1 and PANC‐1, showed that ATX‐LPA signaling promoted cancer cell migration via the activation of the downstream signaling, and this increased cell migration was suppressed by an ATX inhibitor, PF‐8380. An in vivo study showed that PF‐8380 suppressed peritoneal dissemination and decreased malignant ascites, and these results were validated by the biological analysis as well as the in vitro study. Moreover, there was a positive correlation between the amount of ATX in ascites and the degree of disseminated cancer progression. These findings demonstrated that ATX in ascites works as a promotor of peritoneal dissemination, and the targeting of ATX must represent a useful and novel therapy for peritoneal dissemination of PDAC., We could detect the strong inhibitory effect of PF‐8380 on intraperitoneal dissemination of pancreatic ductal adenocarcinoma (PDAC) as it was clearly visualized by bioluminescence imaging and under white‐light imaging.

One class of molecules that are now coming to be recognized as essential for our understanding of the nervous system are the lysophospholipids. One of the major signaling lysophospholipids is lysophosphatidic acid, also known as LPA. LPA activates a variety of G protein-coupled receptors (GPCRs) leading to a multitude of physiological responses. In this review, I describe our current understanding of the role of LPA and LPA receptor signaling in the development and function of the nervous system, especially the central nervous system (CNS). In addition, I highlight how aberrant LPA receptor signaling may underlie neuropathological conditions, with important clinical application.

Endothelial permeability is a major complication that must be addressed during stroke treatment. Study of the mechanisms underlying blood–brain barrier (BBB) disruption and management of the hypoxic stress-induced permeability of the endothelium following reperfusion are both urgently needed for stroke management. Lysophosphatidic acid (LPA), a bioactive lipid essential for basic cellular functions, causes unfavorable outcomes during stroke progression. LPA-producing enzyme autotaxin (ATX) is regulated in ischemic stroke. We used an electrical cell-substrate impedance sensor (ECIS) to measure endothelial permeability. Mitochondrial bioenergetics were obtained using a Seahorse analyzer. AR-2 probe fluorescence assay was used to measure ATX activity. LPA increased endothelial permeability and reduced junctional protein expression in mouse brain microvascular endothelial cells (MBMEC). LPA receptor inhibitors Ki16425 and AM095 attenuated the LPA-induced changes in the endothelial permeability and junctional proteins. LPA significantly diminished mitochondrial function in MBMEC. ATX was upregulated (p < 0.05) in brain microvascular endothelial cells under hypoxic reperfusion. ATX activity and permeability were attenuated with the use of an ATX inhibitor in a mouse stroke model. The upregulation of ATX with hypoxic reperfusion leads to LPA production in brain endothelial cells favoring permeability. Inhibition of the ATX–LPA–LPAR axis could be therapeutically targeted in stroke to achieve better outcomes.

International audience; Lysophosphatidic acid (LPA) is a natural bioactive phospholipid with pleiotropic activities affecting multiple tissues, including bone. LPA exerts its biological functions by binding to G-protein coupled LPA receptors (LPA1-6) to stimulate cell migration, proliferation, and survival. It is largely produced by autotaxin (ATX), a secreted enzyme with lysophospholipase D activity that converts lysophosphatidylcholine (LPC) into active LPA. Beyond its enzymatic activity, ATX serves as a docking molecule facilitating the efficient delivery of LPA to its specific cell surface receptors. Thus, LPA effects are the result of local production by ATX in a given tissue or cell type. As a consequence, the ATX/LPA axis should be considered as an entity to better understand their roles in physiology and pathophysiology and to propose novel therapeutic strategies. Herein, we provide not only an extensive overview of the relevance of the ATX/LPA axis in bone cell commitment and differentiation, skeletal development, and bone disorders, but also discuss new working hypotheses emerging from the interplay of ATX/LPA with well-established signaling pathways regulating bone mass.

Glioblastomas (GBMs) are highly aggressive primary brain tumors characterized by cellular heterogeneity, insensitivity to chemotherapy and poor patient survival. Lysophosphatidic acid (LPA) is a lysophospholipid that acts as a bioactive signaling molecule and plays important roles in diverse biological events during development and disease, including several cancer types. Microglial cells, the resident macrophages of the central nervous system, express high levels of Autotaxin (ATX,Enpp2), an enzyme that synthetizes LPA. Our study aimed to investigate the role of LPA on tumor growth and invasion in the context of microglia-GBM interaction. First, through bioinformatics studies, patient data analysis demonstrated that more aggressive GBM expressed higher levels of ENPP2, which was also associated with worse patient prognosis with proneural GBM. Using GBM-microglia co-culture system we then demonstrated that GBM secreted factors were able to increase LPA1 and ATX in microglia, which could be further enhanced by hypoxia. On the other hand, interaction with microglial cells also increased ATX expression in GBM. Furthermore, microglial-induced GBM proliferation and migration could be inhibited by pharmacological inhibition of LPA1 , suggesting that microglial-derived LPA could support tumor growth and invasion. Finally, increased LPA1 expression was observed in GBM comparing with other gliomas and could be also associated with worse patient survival. These results show for the first time a microglia-GBM interaction through the LPA pathway with relevant implications for tumor progression. A better understanding of this interaction can lead to the development of new therapeutic strategies setting LPA as a potential target for GBM treatment.

Extracellular lysophosphatidate (LPA) signalling is regulated by the balance of LPA formation by autotaxin (ATX) versus LPA degradation by lipid phosphate phosphatases (LPP) and by the relative expressions of six G-protein-coupled LPA receptors. These receptors increase cell proliferation, migration, survival and angiogenesis. Acute inflammation produced by tissue damage stimulates ATX production and LPA signalling as a component of wound healing. If inflammation does not resolve, LPA signalling becomes maladaptive in conditions including arthritis, neurologic pain, obesity and cancers. Furthermore, LPA signalling through LPA1 receptors promotes fibrosis in skin, liver, kidneys and lungs. LPA also promotes the spread of tumours to other organs (metastasis) and the pro-survival properties of LPA explain why LPA counteracts the effects of chemotherapeutic agents and radiotherapy. ATX is secreted in response to radiation-induced DNA damage during cancer treatments and this together with increased LPA1 receptor expression leads to radiation-induced fibrosis. The anti-inflammatory agent, dexamethasone, decreases levels of inflammatory cytokines/chemokines. This is linked to a coordinated decrease in the production of ATX and LPA1/2 receptors and increased LPA degradation through LPP1. These effects explain why dexamethasone attenuates radiation-induced fibrosis. Increased LPA signalling is also associated with cardiovascular disease including atherosclerosis and deranged LPA signalling is associated with pregnancy complications including preeclampsia and intrahepatic cholestasis of pregnancy. LPA contributes to chronic inflammation because it stimulates the secretion of inflammatory cytokines/chemokines, which increase further ATX production and LPA signalling. Attenuating maladaptive LPA signalling provides a novel means of treating inflammatory diseases that underlie so many important medical conditions.

Autotaxin (ATX, also known as ENPP2) is a predominant lysophosphatidic acid (LPA)-producing enzyme in the body, and LPA regulates various physiological functions, such as angiogenesis and wound hea...

International audience; Inflammatory and neuropathic-like components underlie rheumatoid arthritis (RA)-associated pain, and lysophosphatidic acid (LPA) is linked to both joint inflammation in RA patients and to neuropathic pain. Thus, we investigated a role for LPA signalling using the collagen antibody-induced arthritis (CAIA) model. Pain-like behavior during the inflammatory phase and the late, neuropathic-like phase of CAIA was reversed by a neutralizing antibody generated against LPA and by an LPA1/3 receptor inhibitor, but joint inflammation was not affected. Autotaxin, an LPA synthesizing enzyme was upregulated in dorsal root ganglia (DRG) neurons during both CAIA phases, but not in joints or spinal cord. Late-phase pronociceptive neurochemical changes in the DRG were blocked in Lpar1 receptor deficient mice and reversed by LPA neutralization. In vitro and in vivo studies indicated that LPA regulates pain-like behavior via the LPA1 receptor on satellite glia cells (SGCs), which is expressed by both human and mouse SGCs in the DRG. Furthermore, CAIA-induced SGC activity is reversed by phospholipid neutralization and blocked in Lpar1 deficient mice. Our findings suggest that the regulation of CAIA-induced pain-like behavior by LPA signalling is a peripheral event, associated with the DRGs and involving increased pronociceptive activity of SGCs, which in turn act on sensory neurons.

Cauda equina compression (CEC) is a major cause of neurogenic claudication and progresses to neuropathic pain (NP). A lipid mediator, lysophosphatidic acid (LPA), is known to induce NP via the LPA1 receptor. To know a possible mechanism of LPA production in neurogenic claudication, we determined the levels of LPA, lysophosphatidylcholine (LPC) and LPA-producing enzyme autotaxin (ATX), in the cerebrospinal fluid (CSF) and spinal cord (SC) using a CEC as a possible model of neurogenic claudication. Using silicon blocks within the lumbar epidural space, we developed a CEC model in rats with motor dysfunction. LPC and LPA levels in the CSF were significantly increased from day 1. Importantly, specific LPA species (16:0, 18:2, 20:4) were upregulated, which have been shown to produce by ATX detected in the CSF, without changes on its level. In SC, the LPC and LPA levels did not change, but mass spectrometry imaging analysis revealed that LPC was present in a region where the silicon blocks were inserted. These results propose a model for LPA production in SC and CSF upon neurogenic claudication that LPC produced locally by tissue damages is converted to LPA by ATX, which then leak out into the CSF.

Lysophosphatidic acids (LPAs) are bioactive radyl hydrocarbon-substituted derivatives of glycerol 3-phosphate. LPA metabolism and signaling are implicated in heritable risk of coronary artery disease. Genetic and pharmacological inhibition of these processes attenuate experimental atherosclerosis. LPA accumulates in atheromas, which may be a consequence of association with LDLs. The source, regulation, and biological activity of LDL-associated LPA are unknown. We examined the effects of experimental hyperlipidemia on the levels and distribution of circulating LPA in mice. The majority of plasma LPA was associated with albumin in plasma from wild-type mice fed normal chow. LDL-associated LPA was increased in plasma from high-fat Western diet-fed mice that are genetically prone to hyperlipidemia (LDL receptor knockout or activated proprotein convertase subtilisin/kexin type 9-overexpressing C57Bl6). Adipose-specific deficiency of the ENPP2 gene encoding the LPA-generating secreted lysophospholipase D, autotaxin (ATX), attenuated these Western diet-dependent increases in LPA. ATX-dependent increases in LDL-associated LPA were observed in isolated incubated plasma. ATX acted directly on LDL-associated lysophospholipid substrates in vitro. LDL from all human subjects examined contained LPA and was decreased by lipid-lowering drug therapies. Human and mouse plasma therefore contains a diet-sensitive LDL-associated LPA pool that might contribute to the cardiovascular disease-promoting effects of LPA.

Purpose: The objective of the current study was to evaluate the effects of the autotaxin (ATX)–lysophosphatidic acid (LPA) signaling axis on the human trabecular meshwork (HTM) in two-dimensional (2D) and three-dimensional (3D) cultures of HTM cells. Methods: The effects were characterized by transendothelial electrical resistance (TEER) and FITC-dextran permeability (2D), measurements of size and stiffness (3D), and the expression of several genes, including extracellular matrix (ECM) molecules, their modulators, and endoplasmic reticulum (ER) stress-related factors. Results: A one-day exposure to 200 nM LPA induced significant down-sizing effects of the 3D HTM spheroids, and these effects were enhanced slightly on longer exposure. The TEER and FITC-dextran permeability data indicate that LPA induced an increase in the barrier function of the 2D HTM monolayers. A one-day exposure to a 2 mg/L solution of ATX also resulted in a significant decrease in the sizes of the 3D HTM spheroids, and an increase in stiffness was also observed. The gene expression of several ECMs, their regulators and ER-stress related factors by the 3D HTM spheroids were altered by both ATX and LPA, but in different manners. Conclusions: The findings presented herein suggest that ATX may have additional roles in the human TM, in addition to the ATX–LPA signaling axis.

Background Autotaxin is an enzyme that converts lysophospholipid into lysophosphatidic acid (LPA), a highly potent signaling molecule through a range of LPA receptors. It is therefore important to investigate which factors play a role in regulating ATX expression. Since we have reported that ATX levels increase dramatically in patients with various forms of cholestasis, we embarked on a study to reveal factors that influence the enzyme activity ATX as well as its expression level in vitro and in vivo. Methods Bile from cholestatic patients was fractionated by HPLC and analyzed for modulation of ATX activity. ATX expression was measured in fibroblasts upon stimulation or inhibition of LPA signaling. Results Surprisingly, ATX activity was stimulated by most forms of its product LPA, but it was inhibited by bile salts and bile salt-like molecules, particularly by 3-OH sulfated bile salts and sulfated progesterone metabolites that are known to accumulate during chronic cholestasis and cholestasis of pregnancy, respectively. Activation of fibroblasts by LPA decreased ATX expression by 72%. Conversely, inhibition of LPA signaling increased ATX expression 3-fold, indicating strong feedback regulation by LPA signaling. In fibroblasts, we could verify that inhibition of ATX activity by bile salts induces its expression. Furthermore, induction of cholestasis in mice causes increased plasma ATX activity. Conclusions Multiple biliary compounds that accumulate in the systemic circulation during cholestasis inhibit ATX activity and thereby increase ATX expression through feedback regulation. This mechanism may contribute to increased serum ATX activity in patients with cholestasis.

A preclinical strategy to broaden the search of potentially effective treatments in amyotrophic lateral sclerosis (ALS) relies on identifying factors controlling motor neuron (MN) excitability. These partners might be part of still unknown pathogenic pathways and/or useful for the design of new interventions to affect disease progression. In this framework, the bioactive membrane-derived phospholipid lysophosphatidic acid (LPA) affects MN excitability through LPA receptor 1 (LPA(1)). Furthermore, LPA(1) knockdown is neuroprotective in transgenic ALS SOD1-G93A mice. On this basis, we raised the hypothesis that the major LPA-synthesizing ectoenzyme, autotaxin (ATX), regulates MN excitability and is a potential target to modulate disease development in ALS mice. We show here that PF-8380, a specific ATX inhibitor, reduced intrinsic membrane excitability (IME) of hypoglossal MNs in brainstem slices, supporting that baseline ATX activity regulates MN IME. PF-8380-induced alterations were prevented by a small-interfering RNA directed against mRNA for lpa(1). These outcomes support that impact of ATX-originated lysophospholipids on MN IME engages, at least, the G-protein-coupled receptor LPA(1). Interestingly, mRNA(atx) levels increased in the spinal cord of pre-symptomatic (1-2 months old) SOD1-G93A mice, thus preceding MN loss. The rise in transcripts levels also occurred in cultured spinal cord MNs from SOD1-G93A embryos, suggesting that mRNA(atx) upregulation in MNs is an etiopathogenic event in the ALS cell model. Remarkably, chronic administration in the drinking water of the orally bioavailable ATX inhibitor PF-8380 delayed MN loss, motor deterioration and prolonged life span in ALS mice. Treatment also led to a reduction in LPA(1)-immunoreactive patches in transgenic animals mostly in MNs. These outcomes support that neuroprotective effects of interfering with ATX in SOD1-G93A mice rely, at least in part, on LPA(1) knockdown in MNs. Therefore, we propose ATX as a potential target and/or a biomarker in ALS and highlight ATX inhibitors as reasonable tools with therapeutic usefulness for this lethal pathology., BFU2015-71422-R (MINECO/FEDER) from Spain's Government; FEDER-UCA18-108475 from the 2014-2020 ERDF Operational Programme and the Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia; LI19/10IN-CO21 from INiBICA to BML and PID2019-110960GB-I00 (MICINN) from Spain's Government to BML and DGF

Background The loss of endothelial integrity increases the risk of intracerebral hemorrhage during ischemic stroke. Adjunct therapeutic targets for reperfusion in ischemic stroke are in need to prevent blood‐brain barrier disruption. Recently, we have shown that endothelial permeability is mediated by lysophosphatidic acid (LPA), but the role of autotaxin, which produces LPA, remains unclear in stroke. We investigate whether autotaxin/LPA axis regulates blood‐brain barrier integrity after cerebral ischemia. Methods and Results Ischemic stroke was induced in mice by middle cerebral artery occlusion for 90 minutes, followed by 24‐hour reperfusion. The therapeutic efficacy of autotaxin/LPA receptor blockade was evaluated using triphenyl tetrazolium chloride staining, Evans blue permeability, infrared imaging, mass spectrometry, and XF24 analyzer to evaluate blood‐brain barrier integrity, autotaxin activity, and mitochondrial bioenergetics. In our mouse model of ischemic stroke, the mRNA levels of autotaxin were elevated 1.7‐fold following the cerebral ischemia and reperfusion (I/R) group compared with the sham. The enzymatic activity of autotaxin was augmented by 4‐fold in the I/R group compared with the sham. Plasma and brain tissues in I/R group showed elevated LPA levels. The I/R group also demonstrated mitochondrial dysfunction, as evidenced by decreased ( P Conclusions Autotaxin‐LPA signaling blockade attenuates blood‐brain barrier disruption and mitochondrial function following I/R, suggesting targeting this axis could be a new therapeutic approach toward treating ischemic stroke.

Lysophosphatidic acid (LPA) is an endogenous lysophospholipid and a bioactive lipid that is synthesized by the enzyme autotaxin (ATX). The ATX–LPA axis has been associated with cognitive dysfunction and inflammatory diseases, mainly in a range of nonalcoholic liver diseases. Recently, preclinical and clinical evidence has suggested a role of LPA signaling in alcohol use disorder (AUD) and AUD-related cognitive function. However, the ATX–LPA axis has not been sufficiently investigated in alcoholic liver diseases. An exploratory study was conducted in 136 participants, 66 abstinent patients with AUD seeking treatment for alcohol (alcohol group), and 70 healthy control subjects (control group). The alcohol group was divided according to the presence of comorbid liver diseases (i.e., fatty liver/steatosis, alcoholic steatohepatitis, or cirrhosis). All participants were clinically evaluated, and plasma concentrations of total LPA and ATX were measured using enzyme-linked immunosorbent assays. Data were primarily analyzed using analysis of covariance (ANCOVA) while controlling for age, body mass index, and sex. Logistic regression models were created to assess the association of the ATX–LPA axis and AUD or liver disease. LPA and ATX were log10-transformed to fit the assumptions of parametric testing.The main results were as follows: total LPA and ATX concentrations were dysregulated in the alcohol group, and patients with AUD had significantly lower LPA (F(1,131) = 10.677, p = 0.001) and higher ATX (F(1,131) = 8.327, p = 0.005) concentrations than control subjects, patients with AUD and liver disease had significantly higher ATX concentrations (post hoc test, p &lt, 0.05) than patients with AUD but not liver disease, significant correlations between AUD-related variables and concentrations of LPA and ATX were only found in the non-liver disease subgroup (the duration of alcohol abstinence with LPA and ATX (r = +0.33, p &lt, 0.05), and the severity of AUD with ATX (rho = −0.33, p &lt, 0.05)), and a logistic regression model with LPA, ATX, and AUD-related variables showed an excellent discriminative power (area under the curve (AUC) = 0.915, p &lt, 0.001) for distinguishing patients with AUD and comorbid liver disease. In conclusion, our data show that the ATX–LPA axis is dysregulated in AUD and suggest this lipid signaling, in combination with relevant AUD-related variables, as a reliable biomarker of alcoholic liver diseases.

Lysophosphatidic acid (LPA) receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Lysophospholipid Receptors [55, 19, 82, 129]) are activated by the endogenous phospholipid LPA. The first receptor, LPA1, was identified as ventricular zone gene-1 (vzg-1) [40], This discovery represented the beginning of the de-orphanisation of members of the endothelial differentiation gene (edg) family, as other LPA and sphingosine 1-phosphate (S1P) receptors were found. Five additional LPA receptors (LPA2,3,4,5,6) have since been identified [82] and their gene nomenclature codified for human LPAR1, LPAR2, etc. (HUGO Gene Nomenclature Committee, HGNC) and Lpar1, Lpar2, etc. for mice (Mouse Genome Informatics Database, MGI) to reflect species and receptor function of their corresponding proteins. The crystal structure of LPA1 is solved and indicates that LPA accesses the extracellular binding pocket, consistent with its proposed delivery via autotaxin [13]. These studies have also implicated cross-talk with endocannabinoids via phosphorylated intermediates that can also activate these receptors. The binding affinities to LPA1 of unlabeled, natural LPA and anandamide phosphate (AEAp) were measured using backscattering interferometry (pKd = 9) [83, 104]. Utilization of this method indicated affinities that were 77-fold lower than when measured using radioactivity-based protocols [128]. Targeted deletion of LPA receptors has clarified signalling pathways and identified physiological and pathophysiological roles. Multiple groups have independently published validation of all six LPA receptors described in these tables, and further validation was achieved using a distinct read-out via a novel TGFα "shedding* assay [48]. LPA has been proposed to be a ligand for GPR35 [94], supported by a study revealing that LPA modulates macrophage function through GPR35 [54]. However chemokine (C-X-C motif) ligand 17 (CXCL17) is reported to be a ligand for GPR35/CXCR8 [76]. Moreover, LPA has also been described as an agonist for the transient receptor potential (Trp) ion channels TRPV1 [87] and TRPA1 [58]. All of these proposed non-GPCR receptor identities require confirmation and are not currently recognized as bona fide LPA receptors.

Cyclic phosphatidic acid (cPA) is a naturally occurring phospholipid mediator that, along with its chemically stabilized analogue 2-carba-cyclic phosphatidic acid (2ccPA), induces various biological activities in vitro and in vivo. Although cPA is similar to lysophosphatidic acid (LPA) in structure and synthetic pathway, some of cPA biological functions apparently differ from those reported for LPA. We previously investigated the pharmacokinetic profile of 2ccPA, which was found to be rapidly degraded, especially in acidic conditions, yielding an unidentified compound. Thus, not only cPA but also its degradation compound may contribute to the biological activity of cPA, at least for 2ccPA. In this study, we determined the structure and examined the biological activities of 2-carba-lysophosphatidic acid (2carbaLPA) as a 2ccPA degradation compound, which is a type of β-LPA analogue. Similar to LPA and cPA, 2carbaLPA induced the phosphorylation of the extracellular signal-regulated kinase and showed potent agonism for all known LPA receptors (LPA1–6) in the transforming growth factor-α (TGFα) shedding assay, in particular for LPA3 and LPA4. 2carbaLPA inhibited the lysophospholipase D activity of autotaxin (ATX) in vitro similar to other cPA analogues, such as 2ccPA, 3-carba-cPA, and 3-carba-LPA (α-LPA analogue). Our study shows that 2carbaLPA is a novel β-LPA analogue with high potential for the activation of some LPA receptors and ATX inhibition.

Lysophosphatidic acid (LPA) receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Lysophospholipid Receptors [55, 19, 82, 129]) are activated by the endogenous phospholipid LPA. The first receptor, LPA1, was identified as ventricular zone gene-1 (vzg-1) [40], This discovery represented the beginning of the de-orphanisation of members of the endothelial differentiation gene (edg) family, as other LPA and sphingosine 1-phosphate (S1P) receptors were found. Five additional LPA receptors (LPA2,3,4,5,6) have since been identified [82] and their gene nomenclature codified for human LPAR1, LPAR2, etc. (HUGO Gene Nomenclature Committee, HGNC) and Lpar1, Lpar2, etc. for mice (Mouse Genome Informatics Database, MGI) to reflect species and receptor function of their corresponding proteins. The crystal structure of LPA1 is solved and indicates that LPA accesses the extracellular binding pocket, consistent with its proposed delivery via autotaxin [13]. These studies have also implicated cross-talk with endocannabinoids via phosphorylated intermediates that can also activate these receptors. The binding affinities to LPA1 of unlabeled, natural LPA and anandamide phosphate (AEAp) were measured using backscattering interferometry (pKd = 9) [83, 104]. Utilization of this method indicated affinities that were 77-fold lower than when measured using radioactivity-based protocols [128]. Targeted deletion of LPA receptors has clarified signalling pathways and identified physiological and pathophysiological roles. Multiple groups have independently published validation of all six LPA receptors described in these tables, and further validation was achieved using a distinct read-out via a novel TGFα "shedding* assay [48]. LPA LPA has been proposed to be a ligand for GPCR35 [94], supported by a recent study revealing that LPA modulates macrophage function through GPR35 [54]. However chemokine (C-X-C motif) ligand 17 (CXCL17) is reported to be a ligand for GPR35/CXCR8 [76]. Moreover, LPA has also been described as an agonist for the transient receptor potential (Trp) ion channels TRPV1 [87] and TRPA1 [58]. All of these proposed non-GPCR receptor identities require confirmation and are not currently recognized as bona fide LPA receptors.

Autotaxin (ATX) plays an important role in (patho-)physiological lysophosphatidic acid (LPA) signaling. Here we describe the establishment of novel cell-based ATX assay formats. ATX-mediated LPA generation is detected by using a stable LPA receptor reporter cell line. In a first assay variant, ATX-mediated LPA generation is started in the absence of cells and the reaction mix is transferred to the reporter cells after stopping the reaction (two-tube assay). In a second assay variant, ATX is added to the reporter cells expressing the known autotaxin binding partners integrin β1, integrin β3 and the LPA receptor 1. LPA generation is started in the presence of cells and is detected in real-time (one-tube assay). Structurally diverse ATX inhibitors with different binding modes were characterized in both cell-based assay variants and were also tested in the well-established biochemical choline release assay. ATX inhibitors displayed similar potencies, regardless if the assay was performed in the absence or presence of cells, and comparable results were obtained in all three assay formats. In summary, our novel cell-based ATX assay formats are well-suited for sensitive detection of enzyme activity as well as for the characterization of ATX inhibitors in the presence and absence of cells.

Lysophosphatidic acid (LPA), a bioactive lipid produced extracellularly by autotaxin (ATX), has been known to induce various pathophysiological events, including cancer cell invasion and metastasis. Discoidin domain receptor 2 (DDR2) expression is upregulated in ovarian cancer tissues, and is closely associated with poor clinical outcomes in ovarian cancer patients. In the present study, we determined a critical role and signaling cascade for the expression of DDR2 in LPA-induced ovarian cancer cell invasion. We also found ectopic expression of ATX or stimulation of ovarian cancer cells with LPA-induced DDR2 expression. However, the silencing of DDR2 expression significantly inhibited ATX- and LPA-induced ovarian cancer cell invasion. In addition, treatment of the cells with pharmacological inhibitors of phosphoinositide 3-kinase (PI3K), Akt, and mTOR abrogated LPA-induced DDR2 expression. Moreover, we observed that HIF-1α, located downstream of the mTOR, is implicated in LPA-induced DDR2 expression and ovarian cancer cell invasion. Finally, we provide evidence that LPA-induced HIF-1α expression mediates Twist1 expression to upregulate DDR2 expression. Collectively, the present study demonstrates that ATX, and thereby LPA, induces DDR2 expression through the activation of the PI3K/Akt/mTOR/HIF-1α/Twist1 signaling axes, aggravating ovarian cancer cell invasion.

Lysophosphatidic acid (LPA) is a bioactive phospholipid with mitogenic and growth factor-like activities affecting cell invasion, cancer progression, and resistance. It is produced mainly by autotaxin and acts on six G-protein-coupled receptors, LPAR1-6. LPA has recently been implicated as a growth factor present in ascites of ovarian cancer patients. However, mitogenic pathways stimulated by LPA via its receptors may involve any novel, thus far uncharacterized, signaling pathway(s). Here we show that three LPA receptors are involved in tumor progression by activation of both the AKT and ERK signaling pathways. CRISPR-edited LPAR2 and LPAR3 knockouts have opposing effects on ERK activation, whereas LPAR6 is involved in the activation of AKT, affecting cell migration and invasion. Our study identifies specific molecular machinery triggered by LPA and its receptors that modulates tumor cells and can serve as therapeutic target in this malignancy.

Autotaxin (ATX) is a soluble extracellular enzyme that is abundant in mammalian plasma and cerebrospinal fluid (CSF). It has two known enzymatic activities, acting as both a phosphodiesterase and a phospholipase. The majority of its biological effects have been associated with its ability to liberate lysophosphatidic acid (LPA) from its substrate, lysophosphatidylcholine (LPC). LPA has diverse pleiotropic effects in the central nervous system (CNS) and other tissues via the activation of a family of six cognate G protein-coupled receptors. These LPA receptors (LPARs) are expressed in some combination in all known cell types in the CNS where they mediate such fundamental cellular processes as proliferation, differentiation, migration, chronic inflammation, and cytoskeletal organization. As a result, dysregulation of LPA content may contribute to many CNS and PNS disorders such as chronic inflammatory or neuropathic pain, glioblastoma multiforme (GBM), hemorrhagic hydrocephalus, schizophrenia, multiple sclerosis, Alzheimer's disease, metabolic syndrome-induced brain damage, traumatic brain injury, hepatic encephalopathy-induced cerebral edema, macular edema, major depressive disorder, stress-induced psychiatric disorder, alcohol-induced brain damage, HIV-induced brain injury, pruritus, and peripheral nerve injury. ATX activity is now known to be the primary biological source of this bioactive signaling lipid, and as such, represents a potentially high-value drug target. There is currently one ATX inhibitor entering phase III clinical trials, with several additional preclinical compounds under investigation. This review discusses the physiological and pathological significance of the ATX-LPA-LPA receptor signaling axis and summarizes the evidence for targeting this pathway for the treatment of CNS diseases.

Objectives Prurigo is a treatment‐resistant inflammatory disease of unknown etiology. Persistent and severe itch is a major and important clinical symptom, but pathological mechanisms and/or actual mediators for itch in prurigo remain to be defined. Methods We investigated blood levels of β‐endorphin, dynorphin A, and autotaxin in adult patients with prurigo (n = 18), including prurigo nodularis, prurigo chronica multiformis, and other forms. Patients with hemodialysis, hepatic dysfunction, and pregnancy were excluded. Immunofluorescence staining for β‐endorphin and autotaxin in lesional skin was also performed. In addition, β‐endorphin and autotaxin synthesis of cultured epidermal keratinocytes in response to several cytokine stimulation was assessed in vitro. Results Blood levels of β‐endorphin were higher in patients with prurigo than in control subjects (n = 20), while dynorphin A levels were comparable in the two groups. Blood autotaxin levels also were increased in patients with prurigo compared to control subjects. On the one hand, epidermal expression of β‐endorphin was increased in skin lesions of prurigo chronica multiformis, but not in prurigo nodularis. On the other hand, enhanced expression of autotaxin was observed in the epidermis in both prurigo nodularis and prurigo chronica multiformis. In vitro studies showed that β‐endorphin‐expressing epidermal keratinocytes increased following stimulation with TNF‐α, interleukin‐31, and/or IFN‐γ. Autotaxin was also detected in the cytoplasm of cultured epidermal keratinocytes. The fraction of autotaxin‐expressing cells increased when stimulated with TNF‐α and/or interleukin‐31. Conclusions Imbalance of opioid receptor signals and/or the autotaxin‐lysophosphatidic acid axis may contribute, at least in part, to the pathogenesis and intractable pruritus in some of the patients with prurigo.

Lysophosphatidic acid (LPA) is a ubiquitous lysophospholipid that induces a wide range of cellular processes such as wound healing, differentiation, proliferation, migration, and survival. LPA signaling is increased in a number of cancers. In Glioblastoma (GBM), the most aggressive brain tumor, autotaxin the enzyme that produces LPA and its receptor LPA1 are overexpressed. LPA1 is preferentially couple to Gαq proteins in these tumors that in turn activates PKCs. PKCs are involved in many cellular processes including proliferation and metastasis. In this study, we aimed to determine if a classical PKC (α isozyme), could be activated through LPA1 in GBM cell lines and if this activation impacts on cell number. We found that LPA1 induces PKCα translocation to the nucleus, but not to the cell membrane after LPA treatment and the cell number diminished when LPA1/PKCα signaling was blocked, suggesting a relevant role of LPA1 and PKCα in GBM growth.

Pancreatic ductal adenocarcinoma (PDAC) develops a pronounced stromal response reflecting an aberrant wound-healing process. This stromal reaction features transdifferentiation of tissue-resident pancreatic stellate cells (PSC) into activated cancer-associated fibroblasts, a process induced by PDAC cells but of unclear significance for PDAC progression. Here, we show that PSCs undergo a dramatic lipid metabolic shift during differentiation in the context of pancreatic tumorigenesis, including remodeling of the intracellular lipidome and secretion of abundant lipids in the activated, fibroblastic state. Specifically, stroma-derived lysophosphatidylcholines support PDAC cell synthesis of phosphatidylcholines, key components of cell membranes, and also facilitate production of the potent wound-healing mediator lysophosphatidic acid (LPA) by the extracellular enzyme autotaxin, which is overexpressed in PDAC. The autotaxin–LPA axis promotes PDAC cell proliferation, migration, and AKT activation, and genetic or pharmacologic autotaxin inhibition suppresses PDAC growth in vivo. Our work demonstrates how PDAC cells exploit the local production of wound-healing mediators to stimulate their own growth and migration. Significance: Our work highlights an unanticipated role for PSCs in producing the oncogenic LPA signaling lipid and demonstrates how PDAC tumor cells co-opt the release of wound-healing mediators by neighboring PSCs to promote their own proliferation and migration. See related commentary by Biffi and Tuveson, p. 578. This article is highlighted in the In This Issue feature, p. 565

The growth factor-like lipid mediator, lysophosphatidic acid (LPA), is a potent signaling molecule that influences numerous physiologic and pathologic processes. Manipulation of LPA signaling is of growing pharmacotherapeutic interest, especially because LPA resembles compounds with drug-like features. The action of LPA is mediated through activation of multiple types of molecular targets, including six G protein-coupled receptors that are clear targets for drug development. However, the LPA signaling has been linked to pathological responses that include promotion of fibrosis, atherogenesis, tumorigenesis, and metastasis. Thus, a question arises: Can we harness, in an LPA-like drug, the many beneficial activities of this lipid without eliciting its dreadful actions? We developed octadecyl thiophosphate (OTP; subsequently licensed as Rx100), an LPA mimic with higher stability in vivo than LPA. This article highlights progress made toward developing analogs like OTP and exploring prosurvival and regenerative LPA signaling. We determined that LPA prevents cell death triggered by various cellular stresses, including genotoxic stressors, and rescues cells condemned to apoptosis. LPA(2) agonists provide a new treatment option for secretory diarrhea and reduce gastric erosion caused by nonsteroidal anti-inflammatory drugs. The potential uses of LPA(2) agonists like OTP and sulfamoyl benzoic acid-based radioprotectins must be further explored for therapeutic uses.

Background The autotaxin/lysophosphatidic acid axis is involved in diverse biological processes including neurodevelopment, inflammation, and immunological functioning. The lysophosphatidic acid 1 receptor has been implicated in the pathophysiology of major depressive disorder and in the mechanism of action of antidepressants. However, it is unclear whether central or peripheral autotaxin levels are altered in patients with major depressive disorder. Methods Serum autotaxin levels were measured by an enzyme-linked immunosorbent assay in 37 patients with major depressive disorder diagnosed using DSM-IV-TR who underwent electroconvulsive therapy and were compared with those of 47 nondepressed controls matched for age and sex between January 2011 and December 2015. Patient serum levels of autotaxin before and after electroconvulsive therapy were also compared. In a separate sample set, cerebrospinal fluid autotaxin levels were compared between 26 patients with major depressive disorder and 27 nondepressed controls between December 2010 and December 2015. A potential association was examined between autotaxin levels and clinical symptoms assessed with the Hamilton Depression Rating Scale. Results Before electroconvulsive therapy, both serum and cerebrospinal fluidautotaxin levels were significantly lower in major depressive disorder patients than in controls (serum: P = .001, cerebrospinal fluid: P = .038). A significantly negative correlation between serum, but not cerebrospinal fluid, autotaxin levels and depressive symptoms was observed (P = .032). After electroconvulsive therapy, a parallel increase in serum autotaxin levels and depressive symptoms improvement was observed (P = .005). Conclusion The current results suggest that serum autotaxin levels are reduced in a state-dependent manner. The reduction of cerebrospinal fluid autotaxin levels suggests a dysfunction in the autotaxin/lysophosphatidic acid axis in the brains of patients with major depressive disorder.

The peritoneal fluid of ovarian carcinoma patients promotes cancer cell invasion and metastatic spread with lysophosphatidic acid (LPA) as a potentially crucial mediator. However, the origin of LPA in ascites and the clinical relevance of individual LPA species have not been addressed. Here, we show that the levels of multiple acyl-LPA species are strongly elevated in ascites versus plasma and are associated with short relapse-free survival. Data derived from transcriptome and secretome analyses of primary ascite-derived cells indicate that (a) the major route of LPA synthesis is the consecutive action of a secretory phospholipase A2 (PLA2 ) and autotaxin, (b) that the components of this pathway are coordinately upregulated in ascites, and (c) that CD163+CD206+ tumor-associated macrophages play an essential role as main producers of PLA2 G7 and autotaxin. The latter conclusion is consistent with mass spectrometry-based metabolomic analyses of conditioned medium from ascites cells, which showed that tumor-associated macrophages, but not tumor cells, are able to produce 20:4 acyl-LPA in lipid-free medium. Furthermore, our transcriptomic data revealed that LPA receptor (LPAR) genes are expressed in a clearly cell type-selective manner: While tumor cells express predominantly LPAR1-3, macrophages and T cells also express LPAR5 and LPAR6 at high levels, pointing to cell type-selective LPA signaling pathways. RNA profiling identified cytokines linked to cell motility and migration as the most conspicuous class of LPA-induced genes in macrophages, suggesting that LPA exerts protumorigenic properties at least in part via the tumor secretome.

The lipid mediator lysophosphatidic acid (LPA) in biological fluids is primarily produced by cleavage of lysophospholipids by the lysophospholipase D enzyme Autotaxin (ATX). LPA has been identified and abundantly detected in the culture medium of various cancer cell types, tumor effusates, and ascites fluid of cancer patients. Our current understanding of the physiological role of LPA established its role in fundamental biological responses that include cell proliferation, metabolism, neuronal differentiation, angiogenesis, cell migration, hematopoiesis, inflammation, immunity, wound healing, regulation of cell excitability, and the promotion of cell survival by protecting against apoptotic death. These essential biological responses elicited by LPA are seemingly hijacked by cancer cells in many ways; transcriptional upregulation of ATX leading to increased LPA levels, enhanced expression of multiple LPA GPCR subtypes, and the downregulation of its metabolic breakdown. Recent studies have shown that overexpression of ATX and LPA GPCR can lead to malignant transformation, enhanced proliferation of cancer stem cells, increased invasion and metastasis, reprogramming of the tumor microenvironment and the metastatic niche, and development of resistance to chemo-, immuno-, and radiation-therapy of cancer. The fundamental role of LPA in cancer progression and the therapeutic inhibition of the ATX-LPA axis, although highly appealing, remains unexploited as drug development to these targets has not reached into the clinic yet. The purpose of this brief review is to highlight some unique signaling mechanisms engaged by the ATX-LPA axis and emphasize the therapeutic potential that lies in blocking the molecular targets of the LPA system.

Endometriosis has been considered as an estrogen (E2)-dependent and progesterone (P4)-resistant disease. On the other hand, lysophosphatidic acid (LPA) has been suggested as a significant modulator of ovarian pathology, acting via both LPA levels and LPA receptor (LPAR) upregulation. Therefore, the objective of the present study was to evaluate LPA concentration as well as LPARs, autotaxin (ATX), and phospholipase A2 (PLA2) expression in ovarian endometriotic cysts and normal endometrium with correlation of the expression of E2 and P4 receptors in endometriotic cysts. The analyses were carried out using the tissues derived from 37 patients with ovarian endometriosis and 20 endometrial samples collected from women without endometriosis were used as a control. We found that ovarian endometriotic cysts are a site of LPA synthesis due to the presence of enzymes involved in LPA synthesis in the tissue. Additionally, when we compared endometriotic cysts versus normal endometrium, we were able to show overexpression of 3 from 6 examined LPARs and both enzymes responsible for LPA synthesis in endometriotic cysts. Finally, we found the correlations between LPARs, ATX, and PLA2 and the expression of E2 and P4 receptors in endometriotic cysts. Owing to the high LPAR2 and LPAR4 transcript and protein expression in endometriotic ovarian cysts and positive correlations of both these receptors with the PR-B and ERβ, respectively, those receptors seem to be the most promising predictors of the endometriotic cysts as well as the main receptors responsible for LPA action in the ovarian endometriosis.

Objective: β cell dedifferentiation may underlie the reversible reduction in pancreatic β cell mass and function in type 2 diabetes (T2D). We previously reported that β cell-specific Sirt3 knockout (Sirt3f/f;Cre/+) mice developed impaired glucose tolerance and glucose-stimulated insulin secretion after feeding with high fat diet (HFD). RNA sequencing showed that Sirt3-deficient islets had enhanced expression of Enpp2 (Autotaxin, or ATX), a secreted lysophospholipase which produces lysophosphatidic acid (LPA). Here, we hypothesized that activation of the ATX/LPA pathway contributed to pancreatic β cell dedifferentiation in Sirt3-deficient β cells. Methods: We applied LPA, or lysophosphatidylcoline (LPC), the substrate of ATX for producing LPA, to MIN6 cell line and mouse islets with altered Sirt3 expression to investigate the effect of LPA on β cell dedifferentiation and its underlying mechanisms. To examine the pathological effects of ATX/LPA pathway, we injected the β cell selective adeno-associated virus (AAV-Atx-shRNA) or negative control AAV-scramble in Sirt3f/f and Sirt3f/f;Cre/+ mice followed by 6-week of HFD feeding. Results: In Sirt3f/f;Cre/+ mouse islets and Sirt3 knockdown MIN6 cells, ATX upregulation led to increased LPC with increased production of LPA. The latter not only induced reversible dedifferentiation in MIN6 cells and mouse islets, but also reduced glucose-stimulated insulin secretion from islets. In MIN6 cells, LPA induced phosphorylation of JNK/p38 MAPK which was accompanied by β cell dedifferentiation. The latter was suppressed by inhibitors of LPA receptor, JNK, and p38 MAPK. Importantly, inhibiting ATX in vivo improved insulin secretion and reduced β cell dedifferentiation in HFD-fed Sirt3f/f;Cre/+ mice. Conclusions: Sirt3 prevents β cell dedifferentiation by inhibiting ATX expression and upregulation of LPA. These findings support a long-range signaling effect of Sirt3 which modulates the ATX-LPA pathway to reverse β cell dysfunction associated with glucolipotoxicity. Published version This study is supported by the General Research Fund of the Research Grant Council, the Hong Kong SAR Government (project reference: RGCECS 24122318 and GRF 14109519). G.A.R. was supported by a Wellcome Trust Investigator Award (212625/Z/18/Z), MRC Programme grant (MR/R022259/1) and a start-up grant from the CR-CHUM, Université de Montréal.

β2-Glycoprotein I (β2-GPI) is a plasma protein that binds to oxidized low-density lipoprotein (LDL) and negatively charged substances, and inhibits platelet activation and blood coagulation. In this study, we investigated the interaction of β2-GPI with a negatively charged lysophosphatidic acid (LPA) in platelet aggregation and blood clotting. Two negatively charged lysophospholipids, LPA and lysophosphatidylserine, specifically inhibited the binding of β2-GPI to oxidized LDL in a concentration-dependent manner. Intrinsic tryptophan fluorescence studies demonstrated that emission intensity of β2-GPI decreases in an LPA-concentration-dependent manner without a shift in wavelength maxima. LPA specifically induced the aggregation of β2-GPI in phosphate-buffered saline, and in incubated plasma and serum, both of which are known to accumulate LPA by the action of lecithin-cholesterol acyltransferase and lysophospholipase D/autotaxin. β2-GPI aggregated by LPA did not inhibit activated von Willebrand factor-induced aggregation, and did not prolong the activated partial thromboplastin time in blood plasma, in contrast to non-aggregated β2-GPI. These results suggest that β2-GPI aggregated by the binding to LPA fails to inhibit platelet aggregation and blood clotting in contrast to non-aggregated β2-GPI.

Autotaxin (ATX or ENPP2) is a secreted lysophospholipase D that produces lysophosphatidic acid (LPA), a pleiotropic lipid mediator acting on specific GPCRs. ATX and LPA have been implicated in key (patho)physiologic processes, including embryonic development, lymphocyte homing, inflammation, and cancer progression. Using LPA receptor knockout mice, we previously uncovered a role for LPA signaling in promoting colitis and colorectal cancer. Here, we examined the role of ATX in experimental colitis through inducible deletion of Enpp2 in adult mice. ATX expression was increased upon induction of colitis, whereas ATX deletion reduced the severity of inflammation in both acute and chronic colitis, accompanied by transient weight loss. ATX expression in lymphocytes was strongly reduced in Rag1(−/−) and μMT mice, suggesting B cells as a major ATX-producing source, which was validated by immunofluorescence and biochemical analyses. ATX secretion by B cells from control, but not Enpp2 knockout, mice led to ERK activation in colorectal cancer cells and promoted T cell migration. We conclude that ATX deletion suppresses experimental colitis and that B cells are a major source of ATX in the colon. Our study suggests that pharmacological inhibition of ATX could be a therapeutic strategy in colitis.—Lin, S., Haque, A., Raeman, R., Guo, L., He, P., Denning, T. L., El-Rayes, B., Moolenaar, W. H., Yun, C. C. Autotaxin determines colitis severity in mice and is secreted by B cells in the colon.

Obesity is associated with increased cardiovascular morbidity and mortality, but the direct signals to initiate or exaggerate cardiomyopathy remain largely unknown. Present study aims to explore the pathophysiological role of autotaxin/lysophosphatidic acid (LPA) in the process of cardiomyopathy during obesity. Through utilizing mouse model and clinical samples, present study investigates the therapeutic benefits of autotaxin inhibitor and clinical correlation to obesity‐related cardiomyopathy. The elevated circulating levels of autotaxin are closely associated with cardiac parameters in mice. Administration with autotaxin inhibitor, PF‐8380 effectively attenuates high fat diet‐induced cardiac hypertrophy, dysfunction and inflammatory response. Consistently, autotaxin inhibition also decreases circulating LPA levels in obese mice. In in vitro study, LPA directly initiates cell size enlargement and inflammation in neonatal cardiomyocytes. More importantly, circulating levels of autotaxin are positively correlated with cardiac dysfunction and hypertrophy in 55 patients. In conclusion, present study uncovers the correlation between circulating autotaxin and cardiac parameters in mice and human patient, and provided solid evidence of the therapeutic application of autotaxin inhibitor in combating obesity‐related cardiomyopathy.

Lysophospholipids (LPLs), particularly sphingosine 1-phosphate (S1P) and lysophosphatidic acid (LPA), are bioactive lipid modulators of cellular homeostasis and pathology. The discovery and characterization of five S1P- and six LPA-specific G protein-coupled receptors (GPCRs), S1P(1–5) and LPA(1–6), has expanded their known involvement in all mammalian physiological systems. Resolution of the S1P(1), LPA(1), and LPA(6) crystal structures has fueled the growing interest in these receptors and their ligands as targets for pharmacological manipulation. In this review, we have attempted to provide an integrated overview of the three crystallized LPL GPCRs with biochemical and physiological structure-function data. Finally, we provide a novel discussion of how chaperones for LPLs may be considered when extrapolating crystallographic and computational data towards understanding actual biological interactions and phenotypes.

Background Lysophosphatidic acid (LPA), generated extracellularly by the action of autotaxin and phospholipase A2, functions through LPA receptors (LPARs) or sphingosine-1-phosphate receptors (S1PRs) to induce pro-fibrotic signaling in the lower respiratory tract of patients with idiopathic pulmonary fibrosis (IPF). We hypothesized that LPA induces changes in small airway epithelial (SAE) basal cells (BC) that create cross-talk between the BC and normal human lung fibroblasts (NHLF), enhancing myofibroblast formation. Methods To assess LPA-induced signaling, BC were treated with LPA for 2.5 min and cell lysates were analyzed by phosphokinase array and Western blot. To assess transcriptional changes, BC were treated with LPA for 3 h and harvested for collection and analysis of RNA by quantitative polymerase chain reaction (qPCR). To assess signaling protein production and function, BC were washed thoroughly after LPA treatment and incubated for 24 h before collection for protein analysis by ELISA or functional analysis by transfer of conditioned medium to NHLF cultures. Transcription, protein production, and proliferation of NHLF were assessed. Results LPA treatment induced signaling by cAMP response element-binding protein (CREB), extracellular signal-related kinases 1 and 2 (Erk1/2), and epithelial growth factor receptor (EGFR) resulting in elevated expression of connective tissue growth factor (CTGF), endothelin-1 (EDN1/ET-1 protein), and platelet derived growth factor B (PDGFB) at the mRNA and protein levels. The conditioned medium from LPA-treated BC induced NHLF proliferation and increased NHLF expression of collagen I (COL1A1), smooth muscle actin (ACTA2), and autotaxin (ENPP2) at the mRNA and protein levels. Increased autotaxin secretion from NHLF correlated with increased LPA in the NHLF culture medium. Inhibition of CREB signaling blocked LPA-induced changes in BC transcription and translation as well as the pro-fibrotic effects of the conditioned medium on NHLF. Conclusion Inhibition of CREB signaling may represent a novel target for alleviating the LPA-induced pro-fibrotic feedback loop between SAE BC and NHLF.

Autotaxin (ATX) is a secreted glycoprotein and functions as a key enzyme to produce extracellular lysophosphatidic acid (LPA). LPA interacts with at least six G protein-coupled receptors, LPAR1-6, on the cell membrane to activate various signal transduction pathways through distinct G proteins, such as Gi/0, G12/13, Gq/11, and Gs. The ATX-LPA axis plays an important role in physiological and pathological processes, including embryogenesis, obesity, and inflammation. ATX is one of the top 40 most unregulated genes in metastatic cancer, and the ATX-LPA axis is involved in the development of different types of cancers, such as colorectal cancer, ovarian cancer, breast cancer, and glioblastoma. ATX expression is under multifaceted controls at the transcription, post-transcription, and secretion levels. ATX and LPA in the tumor microenvironment not only promote cell proliferation, migration, and survival, but also increase the expression of inflammation-related circuits, which results in poor outcomes for patients with cancer. Currently, ATX is regarded as a potential cancer therapeutic target, and an increasing number of ATX inhibitors have been developed. In this review, we focus on the mechanism of ATX expression regulation and the functions of ATX in cancer development.

Portoenterostomy is the standard treatment for biliary atresia (BA) that reduces jaundice in two thirds of cases. However, progressive liver fibrosis is common, leading to cirrhosis in most patients. Autotaxin is a new marker for the progression of hepatic fibrosis. We examined the relationship between serum autotaxin levels and liver histological findings in patients with BA.BA patients with native livers were identified in our hospital. Patients underwent protocol liver biopsies every 1 to 5 years, and liver fibrosis was evaluated based on the METAVIR score. Serum autotaxin levels were compared with the last available pathological findings.Thirty-five patients were included and the median age was 10.6 years. Serum autotaxin levels was median 1.6 mg/L. The mean autotaxin level was 1.08 mg/L in F0, 1.07 mg/L in F1, 0.95 mg/L in F2, 2.17 mg/L in F3, and 2.50 mg/L in F4; it was significantly higher in F4 than in F0-F2 (P0.0024). For predicting cirrhosis (F4) and advanced liver fibrosis (≥F3), autotaxin had the almost same areas under the curve (AUCs 0.78 and 0.90, respectively) as well as M2BPGi.Autotaxin levels could be used to evaluate the status of native liver fibrosis.

Introduction: Ischemic stroke is a leading cause of death and a serious cause of long-term disability in the US. r-TPA is the only treatment available for stroke. Only 5% of patients receive it, as others have the risk of intracerebral hemorrhage. Ischemic reperfusion (I/R) following stroke exacerbates the condition and initiates various molecular signals, ultimately interrupting blood-brain barrier BBB so, better therapy is in need. Lysophosphatidic acid (LPA) is a bioactive lipid regulating various essential cellular functions such as migration, proliferation, adhesion. Autotaxin (ATX) produces LPA, which then regulates through its six G-protein coupled receptors. Methods: Transient middle cerebral artery occlusion (MCAO) with 90 minutes of ischemia and 24 hours of reperfusion was used as a stroke model in mice. LPA was analyzed in plasma with mass spectrometry and in tissue with immunohistochemistry. AR-2 probe fluorescence measured ATX activity. Seahorse analyzer measured the mitochondrial bioenergetics in brain and mouse brain microvascular endothelial cells (MBMEC). Permeability was studied with Electric Cell Substrate Impedance System. Results: ATX was elevated in mRNA level with 1.7 fold increased activity following I/R. LPA showed a significant (P Conclusion: We have shown that LPA and its regulator enzyme ATX play a significant role in ischemic stroke, increasing BBB permeability, and elevating mitochondrial dysfunction. ATX inhibitors as therapy could improve the condition of stroke patients.

Lumbar spinal canal stenosis (LSS) or mechanical compression of dorsal root ganglion (DRG) is one of the causes of low back pain and neuropathic pain (NP). Lysophosphatidic acid (LPA) is a potent bioactive lipid mediator that is produced mainly from lysophosphatidylcholine (LPC) via autotaxin (ATX) and is known to induce NP via LPA1 receptor signaling in mice. Recently, we demonstrated that LPC and LPA were higher in cerebrospinal fluid (CSF) of patients with LSS. Based on the possible potential efficacy of the ATX inhibitor for NP treatment, we used an NP model with compression of DRG (CD model) and investigated LPA dynamics and whether ATX inhibition could ameliorate NP symptoms, using an orally available ATX inhibitor (ONO-8430506) at a dose of 30 mg/kg. In CD model, we observed increased LPC and LPA levels in CSF, and decreased threshold of the pain which were ameliorated by oral administration of the ATX inhibitor with decreased microglia and astrocyte populations at the site of the spinal dorsal horn projecting from injured DRG. These results suggested possible efficacy of ATX inhibitor for the treatment of NP caused by spinal nerve root compression and involvement of the ATX-LPA axis in the mechanism of NP induction.

Background Pancreatic cancer (PC) is a devastating disease that has a poor prognosis and a total 5-year survival rate of around 5%. The poor prognosis of PC is due in part to a lack of suitable biomarkers that can allow early diagnosis. The lysophospholipase autotaxin (ATX) and its product lysophosphatidic acid (LPA) play an essential role in disease progression in PC patients and are associated with increased morbidity in several types of cancer. In this study, we evaluated both the potential role of serum LPA and ATX as diagnostic markers in PC and their prognostic value for PC either alone or in combination with CA19-9. Methods ATX, LPA and CA19-9 levels were evaluated using ELISA of serum obtained from PC patients (n = 114) healthy volunteers (HVs: n = 120) and patients with benign pancreatic diseases (BPDs: n = 94). Results Serum levels of ATX, LPA and CA19-9 in PC patients were substantially higher than that for BPD patients or HVs (p p = 0.0012). Conclusion Measurement of LPA and ATX levels together with CA19-9 levels can be used for early detection of PC and diagnosis of PC in general.

Lysophosphatidic acid (LPA) is a potent signaling lipid, and state-dependent alterations in plasma LPA make it a promising diagnostic marker for various diseases. However, plasma LPA concentrations vary widely among reports, even under normal conditions. These variations can be attributed, at least in part, to the artificial metabolism of LPA after blood collection. Here, we aimed to develop an optimized plasma preparation method that reflects the concentration of LPA in the circulating blood. The main features of the devised method were suppression of both LPA production and degradation after blood collection by keeping whole blood samples at low temperature followed by the addition of an autotaxin inhibitor to plasma samples. Using this devised method, the LPA level did not change for 30 min after blood collection. Also, human and mouse LPA levels were found to be much lower than those previously reported, ranging from 40 to 50 nM with minimal variation across the individual. Finally, the increased accuracy made it possible to detect circadian rhythms in the levels of certain LPA species in mouse plasma. These results demonstrate the usefulness of the devised plasma preparation method to determine accurate plasma LPA concentrations.

BACKGROUND & AIMS Acute-on-chronic liver failure (ACLF) is characterized by systemic inflammation, monocyte dysfunction, and susceptibility to infection. Lysophosphatidylcholines (LPCs) are immune-active lipids whose metabolic regulation and effect on monocyte function in ACLF is open for study. APPROACHES & RESULTS Three hundred forty-two subjects were recruited and characterized for blood lipid, cytokines, phospholipase (PLA), and autotaxin (ATX) concentration. Peripheral blood mononuclear cells and CD14+ monocytes were cultured with LPC, or its autotaxin (ATX)-derived product, lysophosphatidic acid (LPA), with or without lipopolysaccharide stimulation and assessed for surface marker phenotype, cytokines production, ATX and LPA-receptor expression, and phagocytosis. Hepatic ATX expression was determined by immunohistochemistry. Healthy volunteers and patients with sepsis or acute liver failure served as controls. ACLF serum was depleted in LPCs with up-regulated LPA levels. Patients who died had lower LPC levels than survivors (area under the receiver operating characteristic curve, 0.94; P

The ATX-LPA axis is an attractive target for therapeutic intervention in a variety of diseases, such as tumor metastasis, fibrosis, pruritus, multiple sclerosis, inflammation, autoimmune conditions, metabolic syndrome, and so on. Accordingly, considerable efforts have been devoted to the development of new chemical entities capable of modulating the ATX-LPA axis.This review aims to provide an overview of novel ATX inhibitors reported in patents from September 2016 to August 2020, discussing their structural characteristics and inhibitory potencyIn the past four years, the classification of ATX inhibitors based on binding modes has brought great benefits to the discovery of more efficacious inhibitors. In addition to GLPG1690 currently in phase III clinical studies for IPF, BBT-877, and BLD-0409 as potent ATX inhibitors have been enrolled in phase I clinical evaluation; meanwhile, many effective molecules were also reported successively. However, most emerging ATX inhibitors in the last four years are closely analogs of previous entities, such as GLPG1690 and PF-8380, which translate into the urgently identification of ATX inhibitors with diverse structural features and promising properties in the near future.