Lysophosphatidic acid level and the incidence of silent brain infarction in patients with nonvalvular atrial fibrillation

Lysophospholipid receptors in neurodegeneration and neuroprotection

The central nervous system (CNS) is one of the most complex physiological systems, and treatment of CNS disorders represents an area of major medical need. One critical aspect of the CNS is its lack of regeneration, such that damage is often permanent. The damage often leads to neurodegeneration, and so strategies for neuroprotection could lead to major medical advances. The G protein-coupled receptor (GPCR) family is one of the major receptor classes, and they have been successfully targeted clinically. One class of GPCRs is those activated by bioactive lysophospholipids as ligands, especially sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA). Research has been increasingly demonstrating the important roles that S1P and LPA, and their receptors, play in physiology and disease. In this review, I describe the role of S1P and LPA receptors in neurodegeneration and potential roles in neuroprotection. Much of our understanding of the role of S1P receptors has been through pharmacological tools. One such tool, fingolimod (also known as FTY720), which is a S1P receptor agonist but a functional antagonist in the immune system, is clinically efficacious in multiple sclerosis by producing a lymphopenia to reduce autoimmune attacks; however, there is evidence that fingolimod is also neuroprotective. Furthermore, fingolimod is neuroprotective in many other neuropathologies, including stroke, Parkinson's disease, Huntington's disease, Rett syndrome, Alzheimer's disease, and others that are discussed here. LPA receptors also appear to be involved, being upregulated in a variety of neuropathologies. Antagonists or mutations of LPA receptors, especially LPA1, are neuroprotective in a variety of conditions, including cortical development, traumatic brain injury, spinal cord injury, stroke and others discussed here. Finally, LPA receptors may interact with other receptors, including a functional interaction with plasticity related genes.

Neurological Improvement via Lysophosphatidic Acid Administration in a Rodent Model of Cardiac Arrest-Induced Brain Injury

Lysophosphatidic acid (LPA) serves as a fundamental constituent of phospholipids. While prior studies have shown detrimental effects of LPA in a range of pathological conditions, including brain ischemia, no studies have explored the impact of LPA in the context of cardiac arrest (CA). The aim of this study is to evaluate the effects of the intravenous administration of an LPA species containing oleic acid, LPA (18:1) on the neurological function of rats (male, Sprague Dawley) following 8 min of asphyxial CA. Baseline characteristics, including body weight, surgical procedure time, and vital signs before cardiac arrest, were similar between LPA (18:1)-treated (n = 10) and vehicle-treated (n = 10) groups. There was no statistically significant difference in 24 h survival between the two groups. However, LPA (18:1)-treated rats exhibited significantly improved neurological function at 24 h examination (LPA (18:1), 85.4% ± 3.1 vs. vehicle, 74.0% ± 3.3, p = 0.045). This difference was most apparent in the retention of coordination ability in the LPA (18:1) group (LPA (18:1), 71.9% ± 7.4 vs. vehicle, 25.0% ± 9.1, p < 0.001). Overall, LPA (18:1) administration in post-cardiac arrest rats significantly improved neurological function, especially coordination ability at 24 h after cardiac arrest. LPA (18:1) has the potential to serve as a novel therapeutic in cardiac arrest.

Neurological consequences of neurovascular unit and brain vasculature damages: potential risks for pregnancy infections and COVID-19-babies

Intragravidic and perinatal infections, acting through either direct viral effect or immune-mediated responses, are recognized causes of liability for neurodevelopmental disorders in the progeny. The large amounts of epidemiological data and the wealth of information deriving from animal models of gestational infections have contributed to delineate, in the last years, possible underpinning mechanisms for this phenomenon, including defects in neuronal migration, impaired spine and synaptic development, and altered activation of microglia. Recently, dysfunctions of the neurovascular unit and anomalies of the brain vasculature have unexpectedly emerged as potential causes at the origin of behavioral abnormalities and psychiatric disorders consequent to prenatal and perinatal infections. This review aims to discuss the up-to-date literature evidence pointing to the neurovascular unit and brain vasculature damages as the etiological mechanisms in neurodevelopmental syndromes. We focus on the inflammatory events consequent to intragravidic viral infections as well as on the direct viral effects as the potential primary triggers. These authors hope that a timely review of the literature will help to envision promising research directions, also relevant for the present and future COVID-19 longitudinal studies.

Lysophosphatidic Acid Signalling in Nervous System Development and Function

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.

Lysophosphatidic acid increased infarct size in the early stage of cerebral ischemia-reperfusion with increased BBB permeability

BACKGROUND

We investigated whether exogenous lysophosphatidic acid (LPA), a phospholipid extracellular signaling molecule, would increase infarct size and blood-brain barrier (BBB) disruption during the early stage of cerebral ischemia-reperfusion, and whether it works through Akt-mTOR-S6K1 intracellular signaling.

MATERIAL AND METHODS

Rats were given either vehicle or LPA 1 mg/kg iv three times during reperfusion after one hour of middle cerebral artery (MCA) occlusion. In another group, prior to administration of LPA, 30 mg/kg of PF-4708671, an S6K1 inhibitor, was injected. After one hour of MCA occlusion and two hours of reperfusion the transfer coefficient (K_i) of ¹⁴C-α-aminoisobutyric acid and the volume of ³H-dextran distribution were determined to measure the degree of BBB disruption. At the same time, the size of infarct was determined and western blot analysis was performed to determine the levels of phosphorylated Akt (p-Akt) and phosphorylated S6 (pS6).

RESULTS

LPA increased the K_i in the ischemic-reperfused cortex (+43%) when compared with Control rats and PF-4708671 pretreatment prevented the increase of K_i by LPA. LPA increased the percentage of cortical infarct out of total cortical area (+36%) and PF-4708671 pretreatment prevented the increase of the infarct size. Exogenous LPA did not significantly change the levels of p-Akt as well as pS6 in the ischemic-reperfused cortex.

CONCLUSION

Our data demonstrate that the increase in BBB disruption could be one of the reasons of the increased infarct size by LPA. S6K1 may not be the major target of LPA. A decrease of LPA during early cerebral ischemia-reperfusion might be beneficial for neuronal survival.

Cerebral Ischemia-Reperfusion Injury: Lysophosphatidic Acid Mediates Inflammation by Decreasing the Expression of Liver X Receptor

Lysophosphatidic acid (LPA), a ubiquitous phospholipid, plays a crucial role in the pathogenesis and pathophysiological process of neurological diseases, which constitute the pathological course after cerebral ischemia. Nevertheless, the molecular mechanisms associated with the pathogenic roles of LPA remain elusive. In this study, we evaluated the expression of the liver X receptor (LXR) and nuclear factor kappa B (NFκB) by Western blotting, quantified the levels of IL-1β, IL-6, TNF-α, and LPA by ELISA, and evaluated apoptosis and infarct by TUNEL (terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling) and TTC (triphenyltetrazolium chloride) staining respectively in Sprague-Dawley (SD) rats after middle cerebral artery occlusion (MCAO). The levels of LPA, an extracellular signaling molecule, increased after ischemia and caused neurological injury effect, decreased the expression level of LXR, and increased the expression level of inflammatory factors (IL-1β, IL-6, and TNF-α) via the NFκB signaling pathway. This elevated LPA-induced pathological process is one of the pathological reactions associated with ischemic brain injury. We present a direct or indirect connection between LPA and LXR in the pathophysiological process. In conclusion, we speculate that the inhibition of LPA generation and administration of LXR agonist may be explored as potential cerebral infarction treatment strategies.

Lysophosphatidic acid receptor 1 (LPA1) plays critical roles in microglial activation and brain damage after transient focal cerebral ischemia

Background

Lysophosphatidic acid receptor 1 (LPA₁) is in the spotlight because its synthetic antagonist has been under clinical trials for lung fibrosis and psoriasis. Targeting LPA₁ might also be a therapeutic strategy for cerebral ischemia because LPA₁ triggers microglial activation, a core pathogenesis in cerebral ischemia. Here, we addressed this possibility using a mouse model of transient middle cerebral artery occlusion (tMCAO).

Methods

To address the role of LPA₁ in the ischemic brain damage, we used AM095, a selective LPA₁ antagonist, as a pharmacological tool and lentivirus bearing a specific LPA₁ shRNA as a genetic tool. Brain injury after tMCAO challenge was accessed by determining brain infarction and neurological deficit score. Role of LPA₁ in tMCAO-induced microglial activation was ascertained by immunohistochemical analysis. Proinflammatory responses in the ischemic brain were determined by qRT-PCR and immunohistochemical analyses, which were validated in vitro using mouse primary microglia. Activation of MAPKs and PI3K/Akt was determined by Western blot analysis.

Results

AM095 administration immediately after reperfusion attenuated brain damage such as brain infarction and neurological deficit at 1 day after tMCAO, which was reaffirmed by LPA₁ shRNA lentivirus. AM095 administration also attenuated brain infarction and neurological deficit at 3 days after tMCAO. LPA₁ antagonism attenuated microglial activation; it reduced numbers and soma size of activated microglia, reversed their morphology into less toxic one, and reduced microglial proliferation. Additionally, LPA₁ antagonism reduced mRNA expression levels of proinflammatory cytokines and suppressed NF-κB activation, demonstrating its regulatory role of proinflammatory responses in the ischemic brain. Particularly, these LPA₁-driven proinflammatory responses appeared to occur in activated microglia because NF-κB activation occurred mainly in activated microglia in the ischemic brain. Regulatory role of LPA₁ in proinflammatory responses of microglia was further supported by in vitro findings using lipopolysaccharide-stimulated cultured microglia, showing that suppressing LPA₁ activity reduced mRNA expression levels of proinflammatory cytokines. In the ischemic brain, LPA₁ influenced PI3K/Akt and MAPKs; suppressing LPA₁ activity decreased MAPK activation and increased Akt phosphorylation.

Conclusion

This study demonstrates that LPA₁ is a new etiological factor for cerebral ischemia, strongly indicating that its modulation can be a potential strategy to reduce ischemic brain damage.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1555-8) contains supplementary material, which is available to authorized users.

Lysophosphatidic acid induces neuronal cell death via activation of asparagine endopeptidase in cerebral ischemia-reperfusion injury

Lysophosphatidic acid (LPA), an extracellular signaling molecule, influences diverse biological events, including the pathophysiological process induced after ischemic brain injury. However, the molecular mechanisms mediating the pathological change after ischemic stroke remain elusive. Here we report that asparagine endopeptidase (AEP), a lysosomal cysteine proteinase, is regulated by LPA during stroke. AEP proteolytically cleaves tau and generates tauN368 fragments, triggering neuronal death. Inhibiting the generation of LPA reduces the expression of AEP and tauN368, and alleviates neuronal cell death. Together, this evidence indicates that the LPA-AEP pathway plays a key role in the pathophysiological process induced after ischemic stroke. Inhibition of LPA could be a useful therapeutic for treating neuronal injury after stroke.

Radiosensitization effect of overexpression of adenovirus-mediated SIRT6 on A549 non-small cell lung cancer cells

OBJECTIVE

To explore the radiosensitization effect of overexpression of silent information regulator 6 (SIRT6) on A549 non-small cell lung cancer (NSCLC) cells.

METHODS

Adenovirus vector Ad-SIRT6 causing overexpression of SIRT6 was established. Western blotting and MTT assay were adopted to detect the level of SIRT6 protein and the inhibitory rate of A549 cell proliferation after different concentrations of adenovirus transduction (0, 25, 100, 200, and 400 pfu/cell) for 24 h. Control group, Ad-null group and Ad-SIRT6 group were designed in this experiment and virus concentration of the latter two groups was 200 pfu/cell. Colony formation assays were employed to test survival fraction (SF) of the 3 groups after 0, 2, 4, 6, 8, 10 X-ray irradiation. Flow cytometry was used to detect the status of cell cycle of 3 groups after 48 h of 4 Gy X-ray irradiation and Western blotting was used to determine the expression of apoptosis-related genes of 3 groups after 48 h of 4 Gy X-ray irradiation.

RESULTS

In the range of 25 ~ 400 pfu/cell, the inhibitory rate of A549 cell proliferation increased as adenovirus concentration raised. The inhibitory rates under the concentrations of 0, 25, 100, 200, and 400 pfu/cell were 0%, 4.23 ± 0.34%, 12.7 ± 2.57%, 22.6 ± 3.38%, 32.2 ± 3.22%, 38.7 ± 4.09% and 47.8 ± 5.58% and there were significantly differences among groups (P < .05). SF in Ad-SIRT6 group was lower than Ad-null and control groups after 4 ~ 10 Gy X-ray irradiation (P < 0.05) and the sensitization enhancement ratio (SER) was 1.35 when compared with control group. Moreover, after 48 h of 4 Gy X-ray irradiation, there appeared a significant increase in G1-phase cell proportion, up-regulated expression of the level of apoptosis-promoting genes (Bax and Cleaved caspase-3), but a obvious decline in S-phase and G2-phase cell proportion and a significant decrease of the level of apoptosis- inhibiting gene (Bal-2) in the Ad-SIRT6 group (P<0.05).

CONCLUSION

The over-expression of adenovirus-mediated SIRT6, which has radiosensitization effect on A549 cells of NSCLC, can inhibit the proliferation of A549 cells and cause G0/G1 phase retardation as well as induce apoptosis of cells.

LPA signaling initiates schizophrenia-like brain and behavioral changes in a mouse model of prenatal brain hemorrhage

Genetic, environmental and neurodevelopmental factors are thought to underlie the onset of neuropsychiatric disorders such as schizophrenia. How these risk factors collectively contribute to pathology is unclear. Here, we present a mouse model of prenatal intracerebral hemorrhage--an identified risk factor for schizophrenia--using a serum-exposure paradigm. This model exhibits behavioral, neurochemical and schizophrenia-related gene expression alterations in adult females. Behavioral alterations in amphetamine-induced locomotion, prepulse inhibition, thigmotaxis and social interaction--in addition to increases in tyrosine hydroxylase-positive dopaminergic cells in the substantia nigra and ventral tegmental area and decreases in parvalbumin-positive cells in the prefrontal cortex--were induced upon prenatal serum exposure. Lysophosphatidic acid (LPA), a lipid component of serum, was identified as a key molecular initiator of schizophrenia-like sequelae induced by serum. Prenatal exposure to LPA alone phenocopied many of the schizophrenia-like alterations seen in the serum model, whereas pretreatment with an antagonist against the LPA receptor subtype LPA1 prevented many of the behavioral and neurochemical alterations. In addition, both prenatal serum and LPA exposure altered the expression of many genes and pathways related to schizophrenia, including the expression of Grin2b, Slc17a7 and Grid1. These findings demonstrate that aberrant LPA receptor signaling associated with fetal brain hemorrhage may contribute to the development of some neuropsychiatric disorders.

Different effects of lysophosphatidic acid on L-type calcium current in neonatal rat ventricular myocytes with and without H2O2 treatment

L-type calcium current (I(Ca-L)) alterations are implicated in various cardiac diseases, and the lysophosphatidic acid (LPA) level increases in several ischemic heart diseases. We investigated the effects of LPA on I(Ca-L) in normal and H2O2-treated neonatal rat ventricular myocytes. LPA treatment (24h) increased the action potential duration (APD) and I(Ca-L) in normal ventricular myocytes, but it decreased these parameters in H2O2-treated myocytes. LPA increased the single-channel open probability of L-type calcium channels in both normal and H2O2-treated myocytes. LPA activated calcineurin (CaN) and induced the cytoplasm-to-nucleus translocation of nuclear factor of activated T-cells (NFAT) in H2O2-treated cardiomyocytes. In H2O2-treated cardiomyocytes, LPA decreased Ca(v)1.2 mRNA and protein expression levels at 4 and 8h, respectively. A CaN inhibitor (FK-506) prevented LPA-induced APD, I(Ca-L), and Ca(v)1.2 mRNA and protein down-regulation. The LPA-induced I(Ca-L) increase in normal cardiomyocytes was CaN-NFAT signaling-independent, and LPA did not affect Ca(v)1.2 mRNA or protein expression. In conclusion, LPA increases the I(Ca-L) in normal ventricular myocytes by increasing the single-channel open probability of L-type calcium channels, and LPA decreases I(Ca-L) in H2O2-treated cardiomyocytes via the CaN-NFAT pathway.

Effect of Withaferin A on A549 cellular proliferation and apoptosis in non-small cell lung cancer

OBJECTIVE

To explore the effect of Withaferin A on A549 cellular proliferation and apoptosis in non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

NSCNC cell line A549 was selected to explore the effect of Withaferin A on A549 cellular proliferation, apoptosis and the PI3K/Akt signal pathway capable of regulating tumor biological behavior by assessment of cellular proliferation, cellular apoptotic rates and cellular cycling as well as by immuno-blotting.

RESULTS

Withaferin A could inhibit A549 cellular proliferation and the control rate was dosage-dependent (P<0.05), which also increased time-dependently with the same dosage of Withaferin A (P<0.05). The apoptotic indexes in A549 cells treated with 0, 2.5, 5.0, 10.0 and 20.0 μmol·L-1 Withaferin A for 48 h were significantly different (P<0.05). In addition, the apoptotic rates of each group in both early and advanced stages were higher than those in 0 μmol·L-1 (P<0.05), which were evidently higher after 48 h than those after 24 h (P<0.05). A549 cells treated by Withaferin A for 48 h were markedly lower in Bcl-2 level and obviously higher in Bax and cleaved caspase-3 levels than those treated by 0 μmol·L-1 Withaferin A (P<0.05), and there were significant differences among 5, 10 and 20 μmol·L-1 Withaferin A (P<0.05). The ratios of A549 cells treated by Withaferin A for 48 h in G0/G1 stage were higher than those in 0 μmol·L-1 , while those in S and G2/M stages were obviously lower than those in G2/M stage, and there were significant differences in 5.0, 10.0 and 20.0 μmol·L-1 Withaferin A (P<0.05). Additionally, p-Akt/Akt values were in reverse association with dosage, and the differences were significant (P<0.05).

CONCLUSION

Withaferin A can inhibit the proliferation and apoptosis of A549 cells by suppressing activation of the PI3K/Akt pathways.

Relationship between lysophosphatidic acid and matrix metalloproteinase-9 plasma concentrations and carotid atheromatous plaque stability in patients with cerebral infarction

Objective:

To investigate the correlation between plasma lysophosphatidic acid (LPA), matrix metalloproteinase (MMP)-9 and carotid atheromatous plaque stability in patients with cerebral infarction.

Method:

Patients with cerebral infarction underwent carotid artery duplex ultrasonography and transcranial Doppler monitoring for detection of microemboli. Patients were stratified by plaque type (no plaque, intima thickening, unstable plaque, stable plaque) and presence or absence of micoremboli. Plasma LPA and MMP-9 were quantified.

Result:

LPA and MMP-9 concentrations were significantly higher and microemboli positivity was significantly more common in patients with unstable plaque ( n = 21) than the other three groups (intima thickening, n = 16; stable plaque n = 41; no plaque; n = 12). There was a significant positive correlation between LPA and MMP-9 concentrations.

Conclusion:

Plasma LPA and MMP-9 concentrations may be useful biomarkers in the clinical identification and prediction of unstable plaque, and in guiding treatment.

The prognostic values of leukocyte Rho kinase activity in acute ischemic stroke

Objective. It has been reported that leukocyte ROCK activity is elevated in patients after ischemic stroke, but it is unclear whether leukocyte ROCK activity is associated with clinical outcomes following acute stroke events. The objective of this study is to investigate if leukocyte ROCK activity can predict the outcomes in patients with acute ischemic stroke. Materials and Methods. We enrolled 110 patients of acute ischemic stroke and measured the leukocyte ROCK activity and plasma level of inflammatory cytokines to correlate the clinical outcomes of these patients. Results. The leukocyte ROCK activity at 48 hours after admission in acute ischemic stroke patients was higher as compared to a risk-matched population. The leukocyte ROCK activity significantly correlated with National Institute of Health Stroke Scale (NIHSS) difference between admission and 90 days after stroke event. Kaplan-Meier survival estimates showed lower stroke-free survival during follow-up period in patients with high leukocyte ROCK activity or plasma hsCRP level. Leukocyte ROCK activity independently predicted the recurrent stroke in patients with atherosclerotic stroke. Conclusions. This study shows elevated leukocyte ROCK activity in patients with ischemic stroke as compared to risk-matched subjects and is an independent predictor for recurrent stroke.

Lysophosphatidic acid in atherosclerotic diseases

Lysophosphatidic acid (LPA) is a potent bioactive phospholipid. As many other biological active lipids, LPA is an autacoid: it is formed locally on demand, and it acts locally near its site of synthesis. LPA has a plethora of biological activities on blood cells (platelets, monocytes) and cells of the vessel wall (endothelial cells, smooth muscle cells, macrophages) that are all key players in atherosclerotic and atherothrombotic processes. The specific cellular actions of LPA are determined by its multifaceted molecular structures, the expression of multiple G-protein coupled LPA receptors at the cell surface and their diverse coupling to intracellular signalling pathways. Numerous studies have now shown that LPA has thrombogenic and atherogenic actions. Here, we aim to provide a comprehensive, yet concise, thoughtful and critical review of this exciting research area and to pinpoint potential pharmacological targets for inhibiting thrombogenic and atherogenic activities of LPA. We hope that the review will serve to accelerate knowledge of basic and clinical science, and to foster drug development in the field of LPA and atherosclerotic/atherothrombotic diseases.