Integrating transformers and many-objective optimization for drug design.

BACKGROUND: Drug design is a challenging and important task that requires the generation of novel and effective molecules that can bind to specific protein targets. Artificial intelligence algorithms have recently showed promising potential to expedite the drug design process. However, existing methods adopt multi-objective approaches which limits the number of objectives. RESULTS: In this paper, we expand this thread of research from the many-objective perspective, by proposing a novel framework that integrates a latent Transformer-based model for molecular generation, with a drug design system that incorporates absorption, distribution, metabolism, excretion, and toxicity prediction, molecular docking, and many-objective metaheuristics. We compared the performance of two latent Transformer models (ReLSO and FragNet) on a molecular generation task and show that ReLSO outperforms FragNet in terms of reconstruction and latent space organization. We then explored six different many-objective metaheuristics based on evolutionary algorithms and particle swarm optimization on a drug design task involving potential drug candidates to human lysophosphatidic acid receptor 1, a cancer-related protein target. CONCLUSION: We show that multi-objective evolutionary algorithm based on dominance and decomposition performs the best in terms of finding molecules that satisfy many objectives, such as high binding affinity and low toxicity, and high drug-likeness. Our framework demonstrates the potential of combining Transformers and many-objective computational intelligence for drug design.

WGCNA analysis of the effect of exogenous BR on leaf angle of maize mutant lpa1.

Leaf angle, as one of the important agronomic traits of maize, can directly affect the planting density of maize, thereby affecting its yield. Here we used the ZmLPA1 gene mutant lpa1 to study maize leaf angle and found that the lpa1 leaf angle changed significantly under exogenous brassinosteroid (BR) treatment compared with WT (inbred line B73). Transcriptome sequencing of WT and lpa1 treated with different concentrations of exogenous BR showed that the differentially expressed genes were upregulated with auxin, cytokinin and brassinosteroid; Genes associated with abscisic acid are down-regulated. The differentially expressed genes in WT and lpa1 by weighted gene co-expression network analysis (WGCNA) yielded two gene modules associated with maize leaf angle change under exogenous BR treatment. The results provide a new theory for the regulation of maize leaf angle by lpa1 and exogenous BR.

Social avoidance and altered hypothalamic-pituitary-adrenal axis in a mouse model of anxious depression: The role of LPA1 receptor.

Anxious depression is a prevalent disease with devastating consequences. Despite the lack of knowledge about the neurobiological basis of this subtype of depression, recently our group has identified a relationship between the LPA1 receptor, one of the six characterized G protein-coupled receptors (LPA1-6) for lysophosphatidic acid, with a mixed depressive-anxiety phenotype. Dysfunctional social behaviors, which have been related to increased activation of the hypothalamus-pituitary-adrenal (HPA) axis, are key symptoms of depression and are even more prominent in patients with comorbid anxiety and depressive disorders. Social behavior and HPA functioning were assessed in animals lacking the LPA1 receptor. For these purposes, we first examined social behaviors in wild-type and LPA1 receptor-null mice. In addition, a dexamethasone (DEX) suppression test was carried out. maLPA1-null mice exhibited social avoidance, a blunted response to DEX administration and an impaired circadian rhythm of corticosterone levels, which are features that are consistently dysregulated in many mental illnesses including anxious depression. Here, we have strengthened the previous experimental evidence for maLPA1-null mice to represent a good animal model of anxious depression, providing an opportunity to explore new therapeutic targets for the treatment of mood disorders, particularly this subtype of depression.

Lead generation from N-[benzyl(4-phenylbutyl)carbamoyl]amino acid as a novel LPA1 antagonist for the treatment of systemic sclerosis.

Lysophosphatidic acid (LPA), a bioactive phospholipid, binds to the G protein-coupled LPA1 receptor on the surfaces of immune cells, to promote progression of fibrosis of the skin and organs through inducing infiltration of immune cells into tissues, chemokine production, inflammatory cytokine production, and fibroblast transformation. Anti-fibrotic effects of LPA1 blockade have been reported in animal models of scleroderma and scleroderma patients. In the study reported herein, we identified the novel urea compound 5 as a hit compound with LPA1 antagonist activity from our in-house library and synthesized the lead compound TP0541640 (18) by structural transformation utilizing a structure-based drug design (SBDD) approach. Compound 18 possessed potent in vitro LPA1 antagonist activity and exhibited a dose-dependent inhibitory effect against LPA-induced histamine release in mice. Furthermore, 18 significantly suppressed collagen production and skin thickening in a mouse model of bleomycin-induced skin fibrosis. Herein, we describe the compound design strategies and in vivo studies in greater detail.

Lysophosphatidic acid receptor LPA1 trafficking and interaction with Rab proteins, as evidenced by Förster resonance energy transfer.

LPA1 internalization to endosomes was studied employing Förster Resonance Energy Transfer (FRET) in cells coexpressing the mCherry-lysophosphatidic acid LPA1 receptors and distinct eGFP-tagged Rab proteins. Lysophosphatidic acid (LPA)-induced internalization was rapid and decreased afterward: phorbol myristate acetate (PMA) action was slower and sustained. LPA stimulated LPA1-Rab5 interaction rapidly but transiently, whereas PMA action was rapid but sustained. Expression of a Rab5 dominant-negative mutant blocked LPA1-Rab5 interaction and receptor internalization. LPA-induced LPA1-Rab9 interaction was only observed at 60 min, and LPA1-Rab7 interaction after 5 min with LPA and after 60 min with PMA. LPA triggered immediate but transient rapid recycling (i.e., LPA1-Rab4 interaction), whereas PMA action was slower but sustained. Agonist-induced slow recycling (LPA1-Rab11 interaction) increased at 15 min and remained at this level, whereas PMA action showed early and late peaks. Our results indicate that LPA1 receptor internalization varies with the stimuli.

TXA2 mediates LPA1-stimulated uterine contraction in late pregnant mouse.

Lysophosphatidic acid (LPA) is known to increase uterine contraction in the estrus cycle and early pregnancy, however, the effect of LPA in late pregnant uterus and its mechanisms are not clear. In the present study, we show the LPA receptor subtypes expressed and the mechanism of LPA-induced contractions in late pregnant mouse uterus. We determined the relative mRNA expression of LPA receptor genes by quantitative PCR and elicited log concentration-response curves to oleoyl-L-α-LPA by performing tension experiments in the presence and absence of nonselective and selective receptor antagonists and inhibitors of the TXA2 pathway. LPA1 was the most highly expressed receptor subtype in the late pregnant mouse uterus and LPA1/2/3 agonist (Oleoyl-L-α LPA) elicited increased contractions in this tissue that had lesser efficacy compared to oxytocin. LPA1/3 antagonist, Ki-16425, and a potent LPA1 antagonist (AM-095) significantly inhibited the LPA-induced contractions. Further, the nonselective COX inhibitor, indomethacin, and potent thromboxane A2 synthase inhibitor, furegrelate significantly impaired LPA-induced contractions. Moreover, selective thromboxane receptor (TP) antagonist, SQ-29548, and Rho kinase inhibitor, Y-27632 almost eliminated LPA-induced uterine contractions. LPA1 stimulation elicits contractions in the late pregnant mouse uterus using the contractile prostanoid, TXA2 and may be targeted to induce labor in uterine dysfunctions/ dystocia.

Targeting the LPA1 signaling pathway for fibrosis therapy: a patent review (2010-present).

INTRODUCTION: Fibrosis is a disease that damages organs and even causes death. Because of the complicated pathogenesis, the development of drugs for fibrosis is challenging. In the lysophosphatidic acid receptor type 1 (LPA1) signaling pathway, LPA1 and its downstream Rho-associated coiled-coil forming protein kinase (ROCK) are related to the process of fibrosis. Targeting LPA1 signaling pathway is a potential strategy for the treatment of fibrosis. AREA COVERED: This review describes the process of fibrosis mediated by the LPA1 signaling pathway and then summarizes LPA1 antagonist patents reported since 2010 and ROCK inhibitor patents since 2017 according to their scaffolds based on the Cortellis Drug Discovery Intelligence database. Information on LPA1 antagonists entering clinical trials is integrated. EXPERT OPINION: Over the past decade, a large number of antagonists targeting the LPA1 signaling pathway have been patented for fibrosis therapy. A limited number of compounds have entered clinical trials. Different companies and research groups have used different scaffolds when designing compounds for fibrosis therapy. Therefore, LPA1 and ROCK are competitive targets for the development of new therapies for fibrosis to provide a potential treatment method for fibrosis in the future.

Effects of a lysophosphatidic acid receptor 1 antagonist on hypertensive renal injury in Dahl-Iwai salt-sensitive rats.

Lysophosphatidic acid (LPA) is a biologically active lysophospholipid, and acts on six types of LPA receptors (LPA1-LPA6). LPA-LPA1 signaling has been suggested as a therapeutic target for inflammatory and fibrotic disorders, including renal fibrosis. In this study, we investigated the effects of AM095, an LPA1 selective antagonist, on hypertensive renal injury in Dahl-Iwai salt-sensitive (DS) rats. We evaluated the preventive as well as therapeutic efficacy of AM095 in reducing proteinuria, and improving impaired renal function and renal fibrosis in the hypertensive DS rat. Preventive administration of AM095 suppressed proteinuria, renal function impairment and renal fibrosis in the hypertensive DS rats. In addition, therapeutic administration of AM095 reduced the levels of proximal tubular injury markers and suppressed renal fibrosis. Furthermore, combined administration of AM095 with an angiotensin-converting enzyme (ACE) inhibitor reduced the levels of proximal tubular injury markers and kidney weight increase, and suppressed renal fibrosis more effectively than administration of either agent alone, independent of the antihypertensive effect of the ACE inhibitor. These results provide the first evidence of the potential efficacy of LPA1 antagonist in suppressing renal injury in hypertensive DS rats, suggesting the promise of LPA1 antagonists as a novel therapeutic option for hypertensive renal injury.

LPA1 antagonist BMS-986020 changes collagen dynamics and exerts antifibrotic effects in vitro and in patients with idiopathic pulmonary fibrosis.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a debilitating lung disease with limited treatment options. A phase 2 trial (NCT01766817) showed that twice-daily treatment with BMS-986020, a lysophosphatidic acid receptor 1 (LPA1) antagonist, significantly decreased the slope of forced vital capacity (FVC) decline over 26 weeks compared with placebo in patients with IPF. This analysis aimed to better understand the impact of LPA1 antagonism on extracellular matrix (ECM)-neoepitope biomarkers and lung function through a post hoc analysis of the phase 2 study, along with an in vitro fibrogenesis model. METHODS: Serum levels of nine ECM-neoepitope biomarkers were measured in patients with IPF. The association of biomarkers with baseline and change from baseline FVC and quantitative lung fibrosis as measured with high-resolution computed tomography, and differences between treatment arms using linear mixed models, were assessed. The Scar-in-a-Jar in vitro fibrogenesis model was used to further elucidate the antifibrotic mechanism of BMS-986020. RESULTS: In 140 patients with IPF, baseline ECM-neoepitope biomarker levels did not predict FVC progression but was significantly correlated with baseline FVC and lung fibrosis measurements. Most serum ECM-neoepitope biomarker levels were significantly reduced following BMS-986020 treatment compared with placebo, and several of the reductions correlated with FVC and/or lung fibrosis improvement. In the Scar-in-a-Jar in vitro model, BMS-986020 potently inhibited LPA1-induced fibrogenesis. CONCLUSIONS: BMS-986020 reduced serum ECM-neoepitope biomarkers, which were previously associated with IPF prognosis. In vitro, LPA promoted fibrogenesis, which was LPA1 dependent and inhibited by BMS-986020. Together these data elucidate a novel antifibrotic mechanism of action for pharmacological LPA1 blockade. Trial registration ClinicalTrials.gov identifier: NCT01766817; First posted: January 11, 2013; https://clinicaltrials.gov/ct2/show/NCT01766817 .

Structure dependence and species sensitivity of in vivo hepatobiliary toxicity with lysophosphatidic acid receptor 1 (LPA1) antagonists.

BMS-986020, BMS-986234 and BMS-986278, are three lysophosphatidic acid receptor 1 (LPA1) antagonists that were or are being investigated for treatment of idiopathic pulmonary fibrosis (IPF). Hepatobiliary toxicity (elevated serum AST, ALT, and ALP, plasma bile acids [BAs], and cholecystitis) was observed in a Phase 2 clinical trial with BMS-986020, and development was discontinued. In dogs and rats, the species used for the pivotal toxicology studies, there was no evidence of hepatobiliary toxicity in the dog while findings in the rat were limited to increased plasma BAs levels (6.1× control), ALT (2.9×) and bilirubin (3.4×) with no histopathologic correlates. Since neither rats nor dogs predicted clinical toxicity, follow-up studies in cynomolgus monkeys revealed hepatobiliary toxicity that included increased ALT (2.0× control) and GLDH (4.9×), bile duct hyperplasia, cholangitis, cholestasis, and cholecystitis at clinically relevant BMS-986020 exposures with no changes in plasma or liver BAs. This confirmed monkey as a relevant species for identifying hepatobiliary toxicity with BMS-986020. In order to assess whether the toxicity was compound-specific or related to LPA1 antagonism, two structurally distinct LPA1 antagonists (BMS-986234 and BMS-986278), were evaluated in rat and monkey. There were no clinical or anatomic pathology changes indicative of hepatobiliary toxicity. Mixed effects on plasma BAs in both rat and monkey has made this biomarker not a useful predictor of the hepatobiliary toxicity. In conclusion, the nonclinical data indicate the hepatobiliary toxicity observed clinically and in monkeys administered BMS-986020 is compound specific and not mediated via antagonism of LPA1.

Targeting autotaxin impacts disease advance in the SOD1-G93A mouse model of amyotrophic lateral sclerosis.

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 (LPA1 ). Furthermore, LPA1  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 lpa1 . These outcomes support that impact of ATX-originated lysophospholipids on MN IME engages, at least, the G-protein-coupled receptor LPA1 . Interestingly, mRNAatx 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 mRNAatx 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 LPA1 -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 LPA1  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.

Molecular Regulation of Lysophosphatidic Acid Receptor 1 Maturation and Desensitization.

Lysophosphatidic acid receptor 1 (LPA1) belongs to the G protein-coupled receptor family. The ligand for LPA1 is LPA, the simplest lysophospholipid. LPA is considered a growth factor and induces cell proliferation, anti-apoptosis, and cell migration. The pro-inflammatory and pro-fibrotic roles of LPA have also been well-demonstrated. Most of the biological functions of LPA are mostly executed through LPA1. The mature form of LPA1 is glycosylated and localized on the plasma membrane. LPA1 is bound to heterotrimetric G proteins and transduces intracellular signaling in response to ligation to LPA. Desensitization of LPA1 negatively regulates LPA1-mediated signaling and the resulting biological functions. Phosphorylation and ubiquitination are well-demonstrated posttranslational modifications of GPCR. In this review, we will discuss our knowledge of LPA1 glycosylation, maturation, and trafficking from the endoplasmic reticulum (ER)/Golgi to the plasma membrane. Moreover, in light of recent findings, we will also discuss molecular regulation of LPA1 internalization and stability.

A blocking peptide stabilizes lysophosphatidic acid receptor 1 and promotes lysophosphatidic acid-induced cellular responses.

G protein-coupled receptors regulate a variety of cellular responses and have been considered as therapeutic targets for human diseases. Lysophosphatidic acid receptor 1 (LPA1) is a receptor for bioactive lysophospholipid, LPA. LPA/LPA1-mediated signaling contributes to inflammatory and fibrotic responses in lung diseases; thus understanding regulation of LPA1 stability is important for modulating LPA/LPA1 signaling. Our previous study has shown that LPA1 is degraded in the Nedd4 like (Nedd4L) E3 ubiquitin ligase-mediated ubiquitin-proteasome system. In the current study, we attempt to identify a peptide that stabilizes LPA1 through disrupting LPA1 association with Nedd4L. LPA treatment induces both endogenous and overexpressed LPA1 degradation, which is attenuated by a proteasome inhibitor, suggesting that LPA1 is degraded in the proteasome. LPA increases phosphorylation of extracellular signal-regulated kinase 1/2 (Erk1/2) and I-κB kinase in lung epithelial cells, and this effect is promoted by overexpression of a peptide (P1) that mimics C-terminal of LPA1. P1, not a control peptide, attenuates LPA-induced LPA1 ubiquitination and degradation, suggesting that P1 stabilizes LPA1. Further, P1 diminishes Nedd4L-mediated degradation of LPA1 and Nedd4L/LPA1 association. In addition to increasing LPA1 signaling, P1 enhances LPA-induced cell migration and gene expression of Elafin, matrix metallopeptidase 1, and serpin family B member 2 in lung epithelial cells. These data suggest that disruption of LPA1 interaction with Nedd4L by P1 increases LPA1 stability and LPA/LPA1 signaling.

LPA1 Receptor Promotes Progesterone Receptor Phosphorylation through PKCα in Human Glioblastoma Cells.

Lysophosphatidic acid (LPA) induces a wide range of cellular processes and its signaling is increased in several cancers including glioblastoma (GBM), a high-grade astrocytoma, which is the most common malignant brain tumor. LPA1 receptor is expressed in GBM cells and its signaling pathways activate protein kinases C (PKCs). A downstream target of PKC, involved in GBM progression, is the intracellular progesterone receptor (PR), which can be phosphorylated by this enzyme, increasing its transcriptional activity. Interestingly, in GBM cells, PKCα isotype translocates to the nucleus after LPA stimulation, resulting in an increase in PR phosphorylation. In this study, we determined that LPA1 receptor activation induces protein-protein interaction between PKCα and PR in human GBM cells; this interaction increased PR phosphorylation in serine400. Moreover, LPA treatment augmented VEGF transcription, a known PR target. This effect was blocked by the PR selective modulator RU486; also, the activation of LPA1/PR signaling promoted migration of GBM cells. Interestingly, using TCGA data base, we found that mRNA expression of LPAR1 increases according to tumor malignancy and correlates with a lower survival in grade III astrocytomas. These results suggest that LPA1/PR pathway regulates GBM progression.

CMTM8 as an LPA1-associated partner mediates lysophosphatidic acid-induced pancreatic cancer metastasis.

BACKGROUND: Lysophosphatidic acid (LPA) is known to promote cancer cell invasiveness through LPA1, but the downstream signaling cascades are still not fully clarified. The CKLF-like MARVEL transmembrane domain-containing (CMTM) family regulates aggressive phenotype in many cancers. METHODS: We performed LPA1 co-immunoprecipitation combined with mass spectrometry to search for LPA1-associated proteins. The role of CMTM8 in mediating the pro-invasive activity of LPA was investigated in pancreatic cancer. RESULTS: We identified CMTM8 as an LPA1-interacting protein. LPA1 and CMTM8 were co-localized in pancreatic cancer cells. LPA treatment led to stabilization of CMTM8 protein, which was impaired by knockdown of LPA1. Depletion of CMTM8 significantly suppressed the migration and invasion of pancreatic cancer cells. Conversely, ectopic expression of CMTM8 enhanced the migratory and invasive capacity of pancreatic cancer cells. CMTM8 depletion blocked the formation of metastatic lesions in the lung. Knockdown of CMTM8 attenuated LPA-induced migration and invasion in pancreatic cancer cells. CMTM8 overexpression stimulated ß-catenin activation through reduction of GSK3ß. In addition, knockdown of ß-catenin dramatically antagonized CMTM8-mediated migration and invasion in pancreatic cancer cells. CONCLUSIONS: CMTM8 serves as a key mediator of LPA-induced invasiveness in pancreatic cancer. The interaction between CMTM8 and LPA1 leads to activation of oncogenic ß-catenin signaling. CMTM8 represents a potential therapeutic target for pancreatic cancer.

Interfering with lysophosphatidic acid receptor edg2/lpa1 signalling slows down disease progression in SOD1-G93A transgenic mice.

AIMS: Alterations in excitability represent an early hallmark in Amyotrophic Lateral Sclerosis (ALS). Therefore, deciphering the factors that impact motor neuron (MN) excitability offers an opportunity to uncover further aetiopathogenic mechanisms, neuroprotective agents, therapeutic targets, and/or biomarkers in ALS. Here, we hypothesised that the lipokine lysophosphatidic acid (lpa) regulates MN excitability via the G-protein-coupled receptor lpa1 . Then, modulating lpa1 -mediated signalling might affect disease progression in the ALS SOD1-G93A mouse model. METHODS: The influence of lpa-lpa1 signalling on the electrical properties, Ca2+ dynamic and survival of MNs was tested in vitro. Expression of lpa1 in cultured MNs and in the spinal cord of SOD1-G93A mice was analysed. ALS mice were chronically treated with a small-interfering RNA against lpa1 (siRNAlpa1 ) or with the lpa1 inhibitor AM095. Motor skills, MN loss, and lifespan were evaluated. RESULTS: AM095 reduced MN excitability. Conversely, exogenous lpa increased MN excitability by modulating task1 'leak' potassium channels downstream of lpa1 . Lpa-lpa1 signalling evoked an excitotoxic response in MNs via voltage-sensitive calcium channels. Cultured SOD1-G93A MNs displayed lpa1 upregulation and heightened vulnerability to lpa. In transgenic mice, lpa1 was upregulated mostly in spinal cord MNs before cell loss. Chronic administration of either siRNAlpa1 or AM095 reduced lpa1 expression at least in MNs, delayed MN death, improved motor skills, and prolonged life expectancy of ALS mice. CONCLUSIONS: These results suggest that stressed lpa-lpa1 signalling contributes to MN degeneration in SOD1-G93A mice. Consequently, disrupting lpa1 slows down disease progression. This highlights LPA1 signalling as a potential target and/or biomarker in ALS.

Expression of lysophosphatidic acid receptor 1 in the adult female mouse pituitary gland.

Lysophosphatidic acid receptor 1 (LPA1) is a receptor of lysophosphatidic acid (LPA). The present study investigated Lpar1 mRNA expression in the mouse pituitary gland by RT-PCR, in situ hybridization, and immunohistochemistry. Lpar1 mRNA was abundantly expressed in the pituitary gland. In situ hybridization and immunohistochemistry revealed over 90 % of a common glycoprotein α-subunit, luteinizing hormone ß-subunit, and thyroid-stimulating hormone ß-subunit immunoreactive cells co-expressed Lpar1 mRNA in the anterior pituitary gland, but few growth hormone, adrenocorticotropic hormone, and prolactin cells co-expressed Lpar1. Furthermore, Lpar1 mRNA levels in the pituitary gland were increased after ovariectomy and decreased after E2 administration. These results demonstrate that LPA1-mediated signaling may play physiological roles in gonadotropes and thyrotropes in the mouse pituitary gland.

Microglial lysophosphatidic acid promotes glioblastoma proliferation and migration via LPA1 receptor.

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.

Activation of Macrophages by Lysophosphatidic Acid through the Lysophosphatidic Acid Receptor 1 as a Novel Mechanism in Multiple Sclerosis Pathogenesis.

Multiple sclerosis (MS) is a neuroinflammatory disease whose pathogenesis remains unclear. Lysophosphatidic acid (LPA) is an endogenous phospholipid involved in multiple immune cell functions and dysregulated in MS. Its receptor LPA1 is expressed in macrophages and regulates their activation, which is of interest due to the role of macrophage activation in MS in both destruction and repair. In this study, we studied the genetic deletion and pharmaceutical inhibition of LPA1 in the mouse MS model, experimental autoimmune encephalomyelitis (EAE). LPA1 expression was analyzed in EAE mice and MS patient immune cells. The effect of LPA and LPA1 on macrophage activation was studied in human monocyte-derived macrophages. We show that lack of LPA1 activity induces milder clinical EAE course and that Lpar1 expression in peripheral blood mononuclear cells (PBMC) correlates with onset of relapses and severity in EAE. We see the same over-expression in PBMC from MS patients during relapse compared with progressive forms of the disease and in stimulated monocyte-derived macrophages. LPA induced a proinflammatory-like response in macrophages through LPA1, providing a plausible way in which LPA and LPA1 dysregulation can lead to the inflammation in MS. These data show a new mechanism of LPA signaling in the MS pathogenesis, prompting further research into its use as a therapeutic target biomarker.