Autotaxin Levels Research Articles

Alteration of the lysophosphatidic acid and its precursor lysophosphatidylcholine levels in spinal cord stenosis: A study using a rat cauda equina compression model

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.

Pruritus in patients with chronic liver disease and serum autotaxin levels in patients with primary biliary cholangitis

BackgroundPruritus is a common symptom seen in patients with chronic liver disease. However, frequency and severity of pruritus in patients with chronic liver disease is unclear. We investigated frequency, severity and predictive factors of pruritus in these patients from a large cohort.MethodsA total of 2477 patients with chronic liver disease without allergies or skin diseases were investigated for itch frequency and severity. Itch severity was self-assessed using pruritus scores using the numerical rating scale (NRS). Multivariate regression analysis was performed to identify factors associated with pruritus. Serum autotaxin levels were measured in patients with primary biliary cholangitis (PBC), and the relationship to liver fibrosis and pruritus was analyzed.ResultsThe frequency of pruritus in patients with chronic liver disease was significantly higher than in subjects without liver disease (29.8 and 16.2%, respectively, P < 0.001). NRS was high in patients with chronic liver disease, especially in those with PBC, as is generally expected. Multivariate analysis identified lower albumin, higher eosinophil count, and etiology of PBC as independent factors associated with severe pruritus (≥5 points of NRS). In patients with PBC, serum autotaxin levels were significantly correlated with liver fibrosis markers such as platelet count and liver stiffness, and hepatobiliary enzymes such as total bilirubin, aspartate aminotransferase and alkaline phosphatase. However, no significant correlations between serum autotaxin levels and frequency and severity of pruritus were observed in patients with PBC.ConclusionThe frequency of pruritus was high in patients with chronic liver disease. Reduction of liver function is associated with severe pruritus based on the large number of patients with chronic liver disease. Serum autotaxin is useful for assessing liver fibrosis and severity of cholangitis; however, it is not a predictive marker for severe pruritus in patients with PBC.

Role of the autotaxin-lysophosphatidic acid axis in glaucoma, aqueous humor drainage and fibrogenic activity

Ocular hypertension due to impaired aqueous humor (AH) drainage through the trabecular meshwork (TM) is a major risk factor for glaucoma, a leading cause of irreversible blindness. However, the etiology of ocular hypertension remains unclear. Although autotaxin, a secreted lysophospholipase D and its catalytic product lysophosphatidic acid (LPA) have been shown to modulate AH drainage through TM, we do not have a complete understanding of their role and regulation in glaucoma patients, TM and AH outflow. This study reports a significant increase in the levels of autotaxin, lysophosphatidylcholine (LPC), LPA and connective tissue growth factor (CTGF) in the AH of Caucasian and African American open angle glaucoma patients relative to age-matched non-glaucoma patients. Treatment of human TM cells with dexamethasone, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) increased the levels of autotaxin protein, a response that was mitigated by inhibitors of glucocorticoid receptor, NF-kB and SMAD3. Dexamethasone, TNF-α, IL-1β and LPC treatment of TM cells also led to an increase in the levels of CTGF, fibronectin and collagen type 1 in an autotaxin dependent manner. Additionally, in perfused enucleated mouse eyes, autotaxin and LPC were noted to decrease, while inhibition of autotaxin was increased aqueous outflow through the TM. Taken together, these results provide additional evidence for dysregulation of the autotaxin-LPA axis in the AH of glaucoma patients, reveal molecular insights into the regulation of autotaxin expression in TM cells and the consequences of autotaxin inhibitors in suppressing the fibrogenic response and resistance to AH outflow through the TM.

P5292Obesity paradox, hyperlipoproteinemia(a), autotaxin concentration and stenotic atherosclerosis of different vascular territories

Abstract Background Controversial data have recently emerged about the role of obesity in the development of cardiovascular diseases, otherwise known as “Obesity paradox”. Autotaxin (ATX) hydrolyzes lysophosphatidylcholine to lysophosphatidic acid, a lipid mediator involved in pathological processes, including obesity. Purpose To investigate the association between obesity and stenotic atherosclerosis of different vascular territories. Methods The study included 1225 patients with results of instrumental examination of coronary, carotid and lower limbs arteries. Stenotic atherosclerosis (≥50%) in any vascular bed was diagnosed in 889 patients. Results The patients were divided into two groups depending on body mass index (BMI) (table). The groups were comparable on age, lipids and frequency of CHD. The obesity negatively associated with lower extremity artery disease (LEAD) (odds ratio (OR) 0.51; 95% CI 0.36–0.72, p&lt;0.01) adjusted for gender, age, smoking, type 2 diabetes, lipids and Lp(a). Multifocal atherosclerosis was also negatively associated with obesity (OR 0.44; 95% CI 0.28–0.71, p&lt;0.01). ATX level was lower in patients with LEAD (median [25; 75%]: 492 [418; 573] ng/ml) vs. patients without LEAD (520 [424; 618] ng/ml, p&lt;0.05). The similar results for ATX concentration were shown for patients with multifocal atherosclerosis vs. without stenotic atherosclerosis: 478 [414; 571] ng/ml vs. 551 [412; 678] ng/ml, p&lt;0.05. The corresponding trend was observed in patients with and without coronary heart disease (CHD) (502 [421; 594] vs. 545 [425; 638] ng/ml, p=0.05). ATX level was associated with BMI (r=0.34, p&lt;0.01) and negatively correlated with LEAD and multifocal atherosclerosis in obesity patients (r=−0.2, p&lt;0.05 in both cases). Characteristics of study groups Parameters Control, BMI &lt;30 kg/m2, n=846 Obesity, BMI ≥30 kg/m2, n=379 Hypertension 585 (69%) 316 (83%)*** Type 2 diabetes 133 (16%) 115 (30%)*** Lipoprotein(a), mg/dl 23.9 [9.0; 54.7] 18.0 [6.6; 49.2]* Lipoprotein(a) ≥30 mg/dl 372 (44%) 137 (36%)* Autotaxin, ng/ml 513.5±137.3 528.4±140.1 Carotid atherosclerosis 293 (35%) 127 (33%) CHD 539 (64%) 206 (54%)** LEAD 224 (26%) 66 (17%)*** *p&lt;0.05, **p&lt;0.005, ***p&lt;0.0005 compare with control group. Conclusion “Obesity paradox” was observed in the patients with LEAD, CHD and multifocal atherosclerosis and it could be associated with lysophosphatidic acid pathway.

P2748Lipoprotein(a) and autotaxin in patients with stenotic atherosclerosis of coronary arteries and aortic valve stenosis

Abstract Background Lipoprotein(a) [Lp(a)] is an independent risk factor of coronary heart disease (CHD) and calcific aortic valve stenosis (CAVS). It has been recently shown that autotaxin (ATX), which breaks down lysophosphatidylcholine, derived from oxidized phospholipids, to lysophosphatidic acid, was strongly associated with CAVS. Purpose The aim of the study was to investigate the role of Lp(a) and ATX in CHD patients with and without CAVS. Methods The study included 438 patients (average age 66±11 years, men 310), 332 had CHD with ≥50% stenosis in at least one coronary artery according to angiography. CAVS was diagnosed with ultrasound. The control group consisted of 106 patients without CHD and CAVS. The concentrations of Lp(a), ATX, lipids and blood cells were measured for all the patients. Results CHD without CAVS (group I) was diagnosed in 287 patients, 45 patients had CHD and CAVS (group II). Patients in both groups were older than patients in the control group (75±8, 66±10 and 61±13 years respectively). ATX level was lower in group I (median [25; 75%]: 493 [406; 583] ng/ml) than in control group (544 [412; 655] ng/ml, p=0.02) or group II (553 [475; 609] ng/ml, p=0.003). Lp(a) was lower in control group (14.5 [5.5; 36.0] mg/dl) than in group I (25.6 [9.7; 58.5] mg/dl, p=0.0004) and group II (23.8 [9.9; 79.1] mg/dl, p=0.02). Elevated level of ATX was positively associated with CAVS in CHD patients, but negatively with CHD in patients without CAVS. We have shown that age, glucose level and neutrophil-lymphocytes index (NLI) could be predictors of CAVS in patients with CHD according to results of logistic regression analysis. Odds ratio of high (QIV) vs. low (QI) Odds ratio (95% confidence interval) Groups Autotaxin Lipoprotein(a) Neutrophil-lymphocytes index I vs. control 0.5 (0.3–0.9)* 2.7 (1.3–5.2)** 2.4 (1.3–4.6)* II vs. control 8.6 (1.1–70.1)* 3.4 (1.2–9.4)* 6.2 (2.2–16.9)** II vs. I 16.6 (2.1–131.1)** 1.3 (0.5–3.2) 2.5 (1.0–6.37)* *p&lt;0.05, **p&lt;0.005. Conclusion Elevated Lp(a) level is a predictor of CHD regardless of calcific aortic valve stenosis, whereas elevated concentration of autotoxin in CHD patients was associated with calcific aortic valve stenosis.

CSF levels of apolipoprotein C1 and autotaxin found to associate with neuropathic pain and fibromyalgia.

ObjectiveNeuropathic pain and fibromyalgia are two common and poorly understood chronic pain conditions that lack satisfactory treatments, cause substantial suffering and societal costs. Today, there are no biological markers on which to base chronic pain diagnoses, treatment choices or to understand the pathophysiology of pain for the individual patient. This study aimed to investigate cerebrospinal fluid (CSF) protein profiles potentially associated with fibromyalgia and neuropathic pain.MethodsCSF samples were collected from 25 patients with neuropathic pain (two independent sets, n=14 patients for discovery, and n=11 for verification), 40 patients with fibromyalgia and 134 controls without neurological disease from two different populations. CSF protein profiling of 55 proteins was performed using antibody suspension bead array technology.ResultsWe found increased levels of apolipoprotein C1 (APOC1) in CSF of neuropathic pain patients compared to controls and there was a trend for increased levels also in fibromyalgia patients. In addition, levels of ectonucleotide pyrophosphatase family member 2 (ENPP2, also referred to as autotaxin) were increased in the CSF of fibromyalgia patients compared to all other groups including patients with neuropathic pain.ConclusionThe increased levels of APOC1 and ENPP2 found in neuropathic pain and fibromyalgia patients may shed light on the underlying mechanisms of these conditions. Further investigation is required to elucidate their role in maintaining pain and other main symptoms of these disorders.

Abrogation of lysophosphatidic acid receptor 1 ameliorates murine vasculitis

BackgroundLysophosphatidic acid (LPA), generated by autotaxin (ATX), is a bioactive lipid mediator that binds to the receptors (LPA1–6), and serves as an important mediator in inflammation. Previous studies have demonstrated that LPA-LPA1 cascade contributes to arthritis and skin sclerosis. In this study, we examined the role of LPA signals in murine Candida albicans water-soluble fraction (CAWS)-induced vasculitis.MethodsATX and LPA receptor expressions were analyzed by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction. Effects of LPA1 inhibition on CAWS-induced vasculitis were evaluated in LPA1-deficient mice or using an LPA1 antagonist, LA-01. Migration activity was assessed using a chemotaxis chamber. The number of migrated fluorescently labeled neutrophils, which were transferred into the vasculitis mice, was counted in the aortic wall. CXCL1 and IL-8 concentrations were determined by enzyme-linked immunosorbent assay.ResultsATX and LPA1 were highly expressed in the inflamed region of CAWS-induced vasculitis. Severity of the vasculitis in LPA1-deficient mice was suppressed. The LPA1 antagonist, LA-01, also ameliorated the CAWS-induced vasculitis. LPA induced neutrophil migration, which was inhibited by LA-01 in vitro. Infiltration of transferred neutrophils from LPA1-deficient mice into the coronary arteries was suppressed. LA-01 also inhibited the infiltration of wild-type neutrophils. Expression of CXCL1 and IL-8 in human endothelial cells was enhanced by LPA, but was inhibited by LA-01. ATX and LPA1 expression levels were higher in the affected skin region of vasculitis patients than in healthy controls.ConclusionsThese results suggest that LPA-LPA1 signaling contributes to the development of vasculitis via chemoattractant production from endothelial cells followed by neutrophil recruitment. Thus, LPA1 has potential as a novel target for vasculitis therapies.

Abstract 290: Lpp3 Deficiency Impairs Mitochondrial Function And Enhances Myocardial Lpa Mediated Signaling

The bioactive lysophosphatidic acid (LPA) plays a well-known role in atherosclerotic disease, whereas, its role in myocardial function remains virtually unexplored. Following acute myocardial infarction, serum LPA concentration rises by six-fold over control human subjects, suggesting LPA may contribute to the pathogenesis of myocardial infarction. LPA production involves hydrolysis of lysophosphatidylcholine by the secreted enzyme autotaxin, whereas lipid phosphate phosphatase-3 (LPP3) catalyzes LPA dephosphorylation to generate lipid products that are not receptor active. We present the first evidence that cardiac ischemia/reperfusion (I/R) injury enhances myocardial autotaxin levels and decreases myocardial LPP3 expression, and this is associated with increased serum LPA levels. Upon reperfusion, reactive oxygen species production arises as a burst of superoxide from mitochondria following I/R injury. The redox-sensitive transcription factor NFAT has been shown to bind to the autotaxin promoter and induce its expression. Therefore, we looked at the autotaxin and LPP3 regulation in mice following I/R injury in the myocardium. After 1h ligation followed by 3h reperfusion in the myocardium, we observed a 3-fold increase in the autotaxin protein levels, whereas LPP3 protein levels were significantly downregulated as observed through Western blot analysis in these myocardial ischemic tissues. Autotaxin and miR-92a mRNA expression levels were significantly upregulated, whereas KLF2 and LPP3 mRNA expressions were significantly downregulated following I/R injury at 24 hours. Western blot analysis showed a 3-fold increase autotaxin protein levels and immunohistochemistry of human infarct tissues at 24 hours showed disruption of the sarcomere with decreased LPP3 staining. We found that I/R injury transactivates miR-92a, and inhibit KLF2, an upstream activator of LPP3. Taken together, us in vivo data, from the myocardial I/R injury and human infarct tissues, suggest that regulation of autotaxin and LPP3 activity might cause the rise in serum LPA levels as reported with acute myocardial infarct patients

Increased β‐endorphin and autotaxin in patients with prurigo

AbstractObjectivesPrurigo 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.MethodsWe 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.ResultsBlood 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.ConclusionsImbalance 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.

LPA5 Is an Inhibitory Receptor That Suppresses CD8 T-Cell Cytotoxic Function via Disruption of Early TCR Signaling.

Persistent T cell antigen receptor (TCR) signaling by CD8 T cells is a feature of cancer and chronic infections and results in the sustained expression of, and signaling by, inhibitory receptors, which ultimately impair cytotoxic activity via poorly characterized mechanisms. We have previously determined that the LPA5 GPCR expressed by CD8 T cells, upon engaging the lysophosphatidic acid (LPA) bioactive serum lipid, functions as an inhibitory receptor able to negatively regulate TCR signaling. Notably, the levels of LPA and autotaxin (ATX), the phospholipase D enzyme that produces LPA, are often increased in chronic inflammatory disorders such as chronic infections, autoimmune diseases, obesity, and cancer. In this report, we demonstrate that LPA engagement selectively by LPA5 on human and mouse CD8 T cells leads to the inhibition of several early TCR signaling events including intracellular calcium mobilization and ERK activation. We further show that, as a consequence of LPA5 suppression of TCR signaling, the exocytosis of perforin-containing granules is significantly impaired and reflected by repressed in vitro and in vivo CD8 T cell cytolytic activity. Thus, these data not only document LPA5 as a novel inhibitory receptor but also determine the molecular and biochemical mechanisms by which a naturally occurring serum lipid that is elevated under settings of chronic inflammation signals to suppress CD8 T cell killing activity in both human and murine cells. As diverse tumors have repeatedly been shown to aberrantly produce LPA that acts in an autocrine manner to promote tumorigenesis, our findings further implicate LPA in activating a novel inhibitory receptor whose signaling may be therapeutically silenced to promote CD8 T cell immunity.

Phospholipid levels in blood during community-acquired pneumonia

Phospholipids, major constituents of bilayer cell membranes, are present in large amounts in pulmonary surfactant and play key roles in cell signaling. Here, we aim at finding clinically useful disease markers in community-acquired pneumonia (CAP) using comprehensive phospholipid profiling in blood and modeling of changes between sampling time points. Serum samples from 33 patients hospitalized with CAP were collected at admission, three hours after the start of intravenous antibiotics, Day 1 (at 12–24 h), Day 2 (at 36–48 h), and several weeks after recovery. A profile of 75 phospholipid species including quantification of the bioactive lysophosphatidylcholines (LPCs) was determined using liquid chromatography coupled to time-of-flight mass spectrometry. To control for possible enzymatic degradation of LPCs, serum autotaxin levels were examined. Twenty-two of the 33 patients with a clinical diagnosis of CAP received a laboratory-verified CAP diagnosis by microbial culture or microbial DNA detection by qPCR. All major phospholipid species, especially the LPCs, were pronouncedly decreased in the acute stage of illness. Total and individual LPC concentrations increased shortly after the initiation of antibiotic treatment, concentrations were at their lowest 3h after the initiation, and increased after Day 1. The total LPC concentration increased by a change ratio of 1.6–1.7 between acute illness and Day 2, and by a ratio of 3.7 between acute illness and full disease resolution. Autotaxin levels were low in acute illness and showed little changes over time, contradicting a hypothesis of enzymatic degradation causing the low levels of LPCs. In this sample of patients with CAP, the results demonstrate that LPC concentration changes in serum of patients with CAP closely mirrored the early transition from acute illness to recovery after the initiation of antibiotics. LPCs should be further explored as potential disease stage biomarkers in CAP and for their potential physiological role during recovery.

Attenuation of surgically-induced osteoarthritis (OA) by inhibition of autotaxin

Purpose: Osteoarthritis (OA) is a chronic, progressive joint disease leading to a poor quality of life. Previously, we have reported that selected Lysophoshatidylcholines (lysoPCs) are increased in animal models of OA (Datta et al., 2017, PMID: 28811491). We also identified that these particular metabolites may promote OA pathogenesis in an autotaxin (ATX) - dependent manner. ATX is an enzyme responsible for the conversion of lysoPC to the inflammatory mediator lysophosphatidic acid (LPA). Previous studies have also shown that ATX levels in plasma and synovial fluid correlate with the severity of knee osteoarthritis (Mabey et al., 2015, PMID: 25659292). Thus, we sought to identify if local pharmacological inhibition of ATX can attenuate surgically-induced OA in vivo and its mechanism of action in vitro. Methods: Nine week-old mice were subjected to surgically-induced OA by destabilizing medial meniscus (DMM surgery). ATX antagonist (PF -8380, Pfizer) was injected intra-articularly in the mouse knee joints at 2nd,4th 6th and 8th week of post surgery. Subsequent knee joints were collected at 10 weeks of post surgery and histopathological changes were evaluated. Primary human chondrocytes were treated with IL-1β/ATX antagonist, and the expression of catabolic markers were determined. Results: Local injection of ATX antagonist reduced the degree of cartilage degeneration in surgically induced OA models compared to saline injected controls. ATX antagonist also reduced the amount of synovitis as compared to controls. Immunohistochemical analysis of mouse knee joints showed decreased expression of catabolic markers (C1-2C and MMP 13) in ATX treated mice compared to control mice. In vitro, ATX antagonist attenuated IL-1β-induced increases in the expression of MMP13 Conclusions: Inhibition of ATX attenuates surgically-induced OA. We are currently investigating the mechanism of action of ATX in attenuating OA. Our data, to date, suggests pre-clinical efficacy of ATX to limit OA progression.

Atorvastatin attenuates lysophosphatidic acid‐induced tau hyperphosphorylation through p38 MAPK kinase pathway in an Alzheimer's disease model

The prevalence of Alzheimer's disease (AD) is currently estimated to be around 6 million cases and is predicted to rapidly increase in the coming decades. The currently approved treatments fail to alter the underlying pathophysiology, provide only modest and temporary symptomatic relief and are associated with several side effects. Recent evidence suggests that vascular factors, in particular, lysophosphatidic acid (LPA), the most bioactive component of oxidized low‐density lipoprotein (oxLDL), play a crucial role in the pathophysiology of AD. Increased levels of LPA lead to activation of several intracellular signaling cascades thereby leading to neuroinflammation and neurodegeneration. Statins are cholesterol lowering agents of proven benefit in vascular disease and are also associated with reduction in circulating oxLDL levels. Additionally, several clinical studies suggest the risk of AD was substantially reduced with statins. Hence, the goal of the proposed research is to evaluate the role of the LPA signaling in AD pathogenesis and the effect of statin (atorvastatin) in attenuating LPA induced cognitive dysfunction. In vitro studies utilizing ShSy5y neuronal cell line showed atorvastatin attenuated LPA induced Amyloid beta and tau hyperphosphorylation. The effect of LPA on p38 MAPK Kinase and it's downstream signaling markers of apoptosis (BAX, BCL2) and inflammation (NF‐Kβ, IL‐6, TNFα) was analyzed through biochemical assays. We will utilize a high fat diet mouse model, to investigate the neuroprotective effects of atorvastatin. Novel object location test, Y‐maze and contextual fear conditioning will be performed to evaluate cognitive and behavioral deficits. To assess the effects of LPA and atorvastatin on hippocampal synaptic plasticity, we will measure long term potentiation and long‐term depression, which are the cellular correlates of learning and memory. Golgi cox staining to study the effect of LPA and atorvastatin on dendritic spine morphology is being performed. Western blot will also be used to measure levels of AMPA and NMDA receptor subunits. Biochemical assays will be performed to quantify levels of PSD‐95, synaptophysin, and ARC protein, which are proteins essential for synaptic maturity and plasticity. Finally, the neuroprotective effect of atorvastatin on LPA induced cognitive dysfunction will be analyzed by measuring the levels of autotaxin (ATX), an enzyme important for LPA synthesis. 4, 8‐ and 12‐months aged age. We believe our study will demonstrate that that atorvastatin through its pleotropic effects, attenuate LPA induced cognitive dysfunction by improving behavioral and cognitive deficits, synaptic dysfunction, and reducing the pathologies of AD thereby uncovering a molecular mechanism of LPA induced dyshomeostasis in AD.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Doxorubicin in myocardial lysophosphatidic acid signaling

Generation of reactive oxygen species has been implicated in the toxicity of nearly 50% of the current FDA approved cancer therapeutic drugs. Mitochondrial respiration is a major source of reactive oxygen species production and that the presence of the mitochondrial antioxidant enzyme, manganese superoxide dismutase, is essential for the survival of all aerobic life. Our studies of animals using the prototype redox‐active anticancer drug, doxorubicin, indicate that overexpression of manganese superoxide dismutase protects the heart against doxorubicin‐induced cardiac injury and reduction of manganese superoxide dismutase by heterozygous knockout mice increases cardiac injury after exposure to doxorubicin. While the bioactive glycerophospholipid lysophosphatidic acid rises by seven‐fold over control subjects, suggesting lysophosphatidic acid may contribute to the doxorubicin‐induced cardiac toxicity. Lysophosphatidic acid production involves hydrolysis of lysophosphatidylcholine by the secreted enzyme autotaxin, whereas lipid phosphate phosphatase‐3 (LPP3) catalyzes lysophosphatidic acid dephosphorylation to generate lipid products that are not receptor active. In this application, we present the first evidence that doxorubicin‐induced cardiac injury enhances myocardial autotaxin levels and decreases myocardial LPP3 expression, and this is associated with increased serum lysophosphatidic acid levels. Reactive oxygen species production arises as a burst of superoxide from mitochondria following doxorubicin‐induced cardiac injury. The redox‐sensitive transcription factor NFAT (a nuclear factor of activated T‐cells) has been shown to bind to the autotaxin promoter and induce its expression. Similarly, oxidant stress may deplete LPP3 levels in the context of cardiac injury through reduced LPP3 expression or enhanced LPP3 degradation. Thus, we hypothesize that doxorubicin‐induced cardiac injury alters autotaxin and LPP3 expression through mitochondrial superoxide production to drive lysophosphatidic acid signaling and cardiomyocyte dysfunction. The following interrelated specific aims are designed to provide step‐wise and in‐depth studies in vitro, in vivo, and in experimental therapeutics settings. Specific aim 1 will assess the role of myocardial superoxide production in autotaxin expression and lysophosphatidic acid production in doxorubicin‐induced cardiac injury. Specific aim 2 will determine the role of mitochondrial superoxide production in LPP3 depletion and lysophosphatidic acid regulation in doxorubicin‐induced cardiac injury. We could identify whether modulation of cellular versus mitochondrial antioxidant status confers a differential protective effect in doxorubicin‐induced cardiac injury models.Support or Funding InformationAAA‐ FGAP Fellow grant funded by the American Association of Anatomists.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Alterations in Skin Microbiomes of Patients With Cirrhosis

Patients with cirrhosis have intestinal dysbiosis and are prone to itching and skin or soft-tissue infections. The skin microbiome, and its relationship with intestinal microbiome, have not been characterized. We investigated alterations in skin microbiota of patients with cirrhosis and their association with intestinal microbiota and modulators of itch. We collected skin swabs at 7 sites and blood and stool samples from 20 healthy individuals (control subjects; mean age, 59 years) and 50 patients with cirrhosis (mean age, 61 years; mean model for end-stage disease score, 12; 20 with decompensation). Skin and stool samples were analyzed by 16s rRNA sequencing and serum samples were analyzed by liquid chromatography and mass spectrometry for levels of bile acids (BAs) and by an ELISA for autotaxin (an itch modulator). Participants were analyzed by the visual analog itch scale (VAS, 0-10,10= maximum intensity). Data were compared between groups (cirrhosis vs control subjects, with vs without decompensation, VAS 5 or higher vs less than 5). Correlation networks between serum levels of BAs and skin microbiomes were compared between patients with cirrhosis with vs without itching. The composition of microbiomes at all skin sites differed between control subjects and patients with cirrhosis and between patients with compensated vs decompensated cirrhosis. Skin microbiomes of patients with cirrhosis (especially those with decompensation) contained a higher relative abundance of Gammaproteobacteria, Streptococaceae, and Staphylococcaceae, and fecal microbiomes contained a higher relative abundance of Gammaproteobacteria, than control subjects. These bacterial taxa were associated with serum levels of autotaxin and BAs, which were higher in patients with VAS scores ≥5. Based on network statistics, microbial and BA interactions at all sites were more complex in patients with greater levels of itching in the shin, the most common site of itch. We identified alterations in skin microbiome of patients with cirrhosis (in Gammaproteobacteria, Streptococcaceae, and Staphylococcaceae)-especially in patients with decompensation; fecal microbiomes of patients with cirrhosis had a higher relative abundance of Gammaproteobacteria than control subjects. These specific microbial taxa are associated with itching intensity and itch modulators, such as serum levels of BAs and autotaxin.

Simiao Pill Attenuates Collagen-Induced Arthritis in Rats through Suppressing the ATX-LPA and MAPK Signalling Pathways.

Objective Simiao pill (SM), a traditional Chinese formula, has been used as an antirheumatic drug in clinical practice for hundreds of years. Rheumatoid arthritis (RA) is characterized by chronic synovial inflammation and hyperplasia, cartilage destruction, and joint damage. This study was designed to investigate the protective effects of SM on collagen-induced arthritis (CIA) in rats. It also aimed to explore whether this protective effect of SM was related to the inhibition of the ATX-LPA and MAPK signalling pathways. Materials and Methods Rats were injected with a collagen II emulsion at the end of the tail and on the back to induce arthritis. Treatment with different doses of SM was conducted by intragastric administration. Then, body weights and arthritis scores were measured. The serum levels of tumour necrosis factor (TNF)-α, interleukin (IL)-1β, C-reactive protein (CRP), osteoprotegerin (OPG), autotaxin (ATX), and lysophosphatidic acid (LPA) were determined by ELISA. Pathological changes in the joints were measured by micro-CT and assessed via haematoxylin-eosin (H&E) staining. The expression of ATX, LPA receptor 1 (LPA1) was detected by immunohistochemical staining, and the expression of mitogen-activated protein kinase (MAPK) was detected by Western blotting. Results SM significantly alleviated arthritis symptoms, inhibited bone erosion, and decreased the levels of TNF-α, IL-1β, CRP, ATX, and LPA in the sera of CIA rats. Importantly, SM clearly reduced the protein expression of LPA1 and ATX. The activation of the MAPK signalling pathway was also inhibited by SM in the synovial tissues of CIA rats. Conclusions The antirheumatic effects of SM were associated with the regulation of the ATX-LPA and MAPK pathways, the suppression of proinflammatory cytokine production, and the alleviation of cartilage and bone injury. These findings suggest that SM might be a promising alternative candidate for RA therapy.

Acute and chronic effect of bariatric surgery on circulating autotaxin levels.

Autotaxin (ATX), an adipose tissue‐derived lysophospholipase, has been involved in the pathophysiology of cardiometabolic diseases. The impact of bariatric surgery on circulating ATX levels is unknown. We examined the short‐ (24 h, 5 days) and longer‐term (6 and 12 months) impact of bariatric surgery; as well as the short‐term effect of caloric restriction (CR) on plasma ATX levels in patients with severe obesity. We measured ATX levels in 69 men and women (mean age: 41 ± 11 years, body mass index: 49.8 ± 7.1 kg/m2), before and after biliopancreatic diversion with duodenal switch surgery (BPD‐DS) as well as in a control group (patients with severe obesity without surgery; n = 34). We also measured ATX levels in seven patients with severe obesity and type 2 diabetes who underwent a 3‐day CR protocol before their BPD‐DS. At baseline, ATX levels were positively associated with body mass index, fat mass, insulin resistance (HOMA‐IR) as well as insulin and leptin levels and negatively with fat‐free mass. ATX concentrations decreased 26.2% at 24 h after BPD‐DS (342.9 ± 152.3 pg/mL to 253.2 ± 68.9 pg/mL, P < 0.0001) and by 16.4% at 12 months after BPD‐DS (342.9 ± 152.3 pg/mL to 286.8 ± 182.6 pg/mL, P = 0.04). ATX concentrations were unchanged during follow‐up in the control group (P = 0.4), and not influenced by short‐term CR. In patients with severe obesity, bariatric surgery induced a rapid and sustained decrease in plasma ATX levels. Acute changes in ATX may not be explained by bariatric surgery‐induced CR.

Autotaxin, bile acid profile and effect of ileal bile acid transporter inhibition in primary biliary cholangitis patients with pruritus.

Pruritus is a common symptom in patients with primary biliary cholangitis (PBC) for which ileal bile acid transporter (IBAT) inhibition is emerging as a potential therapy. We explored the serum metabonome and gut microbiota profile in PBC patients with pruritus and investigated the effect of GSK2330672, an IBAT inhibitor. We studied fasting serum bile acids (BAs), autotaxin and faecal microbiota in 22 PBC patients with pruritus at baseline and after 2weeks of GSK2330672 treatment. Control group included 31 asymptomatic PBC patients and 18 healthy volunteers. BA profiling was done by ultra performance liquid chromatography coupled to a mass spectrometry (UPLC-MS). Faecal microbiomes were analysed by 16S ribosomal RNA gene sequencing. In PBC patients with pruritus, serum levels of total and glyco-conjugated primary BAs and autotaxin were significantly elevated. Autotaxin activity correlated significantly with tauro- and glyco-conjugated cholic acid (CA) and chenodeoxycholic acid (CDCA), both at baseline and after GSK2330672. GSK2330672 significantly reduced autotaxin and all tauro- and glyco- conjugated BAs and increased faecal levels of CA (P=0.048) and CDCA (P=0.027). Gut microbiota of PBC patients with pruritus was similar to control groups. GSK2330672 increased the relative abundance of Firmicutes (P=0.033) and Clostridia (P=0.04) and decreased Bacteroidetes (P=0.033) and Bacteroidia (P=0.04). Pruritus in PBC does not show a distinct gut bacterial profile but is associated with elevated serum bile acid and autotaxin levels which decrease after IBAT inhibition. In cholestatic pruritus, a complex interplay between BAs and autotaxin is likely and may be modified by IBAT inhibition.

Reduced Serum and Cerebrospinal Fluid Levels of Autotaxin in Major Depressive Disorder.

BackgroundThe 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.MethodsSerum 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.ResultsBefore 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).ConclusionThe 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.

Serum autotaxin levels are associated with Graves' disease.

Graves' Disease is a representative autoimmune thyroid disease that presents with hyperthyroidism. Emerging evidence has shown the involvement of lysophosphatidic acid (LPA) and its producing enzyme, autotaxin (ATX), in the pathogenesis of various diseases; among them, the involvement of the ATX/LPA axis in some immunological disturbances has been proposed. In this study, we investigated the association between serum ATX levels and Graves' disease. We measured the levels of serum total ATX and ATX isoforms (classical ATX and novel ATX) in patients with untreated Graves' disease, Graves' disease treated with anti-thyroid drugs, patients with subacute thyroiditis, silent thyroiditis, Plummer's disease, or Hashimoto's thyroiditis, and patients who had undergone a total thyroidectomy, as well as normal subjects. The serum total ATX and ATX isoform levels were higher in the patients with Graves' disease, compared with the levels in the healthy subjects and the patients with subacute thyroiditis. Treatment with anti-thyroid drugs significantly decreased the serum ATX levels. The serum ATX levels and the changes in serum ATX levels during treatment were moderately or strongly correlated with the serum concentrations or the changes in thyroid hormones. However, the administration of T3 or T4 did not increase the expression or serum levels of ATX in 3T3L1 adipocytes or wild-type mice. In conclusion, the serum ATX levels were higher in subjects with Graves' disease, possibly because of a mechanism that does not involve hyperthyroidism. These results suggest the possible involvement of the ATX/LPA axis in the pathogenesis of Graves' disease.