Association of Serum Autotaxin Levels with Liver Fibrosis in Patients with Chronic Hepatitis C. Sci Rep. 2017;7:46705. [PMID: 28425454 PMCID: PMC5397977 DOI: 10.1038/srep46705]

Autotaxin is a potential predictive marker for the development of veno-occlusive disease/sinusoidal obstruction syndrome after allogeneic hematopoietic cell transplantation

Veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) is a life-threatening complication after allogeneic hematopoietic cell transplantation (allo-HCT), and stratification of the high-risk group before transplantation is significant. Serum autotaxin (ATX) levels have been reported to increase in patients with liver fibrosis caused by metabolic inhibition from liver sinusoidal endothelial cells. Considering that the pathophysiology of VOD/SOS begins with liver sinusoidal endothelial cell injury, an increase in serum ATX levels may precede the onset of VOD/SOS. A retrospective study with 252 patients, including 12 patients with VOD/SOS, who had received allo-HCT was performed. The cumulative incidence of VOD/SOS was higher in the group with serum ATX levels before conditioning (baseline ATX) above the upper reference limit (high ATX group, p < 0.001), and 1-year cumulative incidences were 22.7% (95% confidence interval [95%CI], 3.1-42.4%) and 3.5% (95%CI, 1.1-5.8%), respectively. In the multivariate analysis, elevated baseline ATX was identified as an independent risk factor for VOD/SOS development and showed an additive effect on the predictive ability of known risk factors. Furthermore, the incidence of VOD/SOS-related mortality was greater in the high ATX group (16.7% vs. 1.3%; p = 0.005). Serum ATX is a potential predictive marker for the development of VOD/SOS.

Sodium/bile acid co-transporter inhibitors currently in preclinical or early clinical development for the treatment of primary biliary cholangitis

INTRODUCTION

Pruritus is common and often undertreated in patients with primary biliary cholangitis (PBC). Existing treatments largely have an aging and low-quality evidence base, and studies included only small numbers of patients. More recent data that has added to our understanding of pruritus treatments has often come from clinical trials where itching was a secondary outcome measure in a trial designed primarily to assess disease-modifying agents. This area represents an unmet clinical need in the management of PBC.

AREAS COVERED

In this manuscript, we first summarize the proposed mechanisms for PBC-related pruritus and the current treatment paradigm. We then present an appraisal of the existing pre-clinical and clinical evidence for the use of ileal bile acid transporter inhibitors (IBATis) for this indication in PBC patients.

EXPERT OPINION

Evidence for the efficacy of IBATis is promising but limited by the currently available volume of data. Furthermore, larger clinical trials with long-term data on efficacy, safety and tolerability are needed to confirm the role of using IBATis in clinical practice and their place on the itch treatment ladder. Additional focus should also be given to exploring the disease-modifying potential of IBATis in PBC.

Serum autotaxin is a prognostic indicator of liver-related events in patients with non-alcoholic fatty liver disease

BACKGROUND

Circulating autotaxin (ATX) levels have been reported to correlate with liver inflammation activity and liver fibrosis severity in patients with non-alcoholic fatty liver disease (NAFLD). The objective of this study is to investigate whether serum ATX could predict liver-related events (LRE) in NAFLD patients.

METHODS

This retrospective investigation includes 309 biopsy-proven NAFLD patients registered at Shinshu University Hospital. All patients are followed for at least 1 year, during which time the prevalence of LRE, including newly developing hepatocellular carcinoma, hepatic encephalopathy, ascites, and esophagogastric varices, is investigated in relation to ATX levels at the time of liver biopsy.

RESULTS

During the median follow-up period of 7.0 years, LRE are observed in 20 patients (6.5%). The area under the receiver operating characteristic curve and cut-off value of serum ATX for predicting LRE are 0.81 and 1.227 mg/l, respectively. Multivariate Cox proportional hazards models for LRE determine ATX and advanced fibrosis as independently associated factors. Furthermore, in a competing risk analysis that considered non-liver-related death as a competing event, ATX (HR 2.29, 95% CI 1.22-4.30, p = 0.010) is identified as an independent factor associated with LRE, along with advanced fibrosis (HR 8.01, 95% CI 2.10-30.60, p = 0.002). The predictive utility of ATX for LRE is validated in an independent cohort.

CONCLUSIONS

Serum ATX may serve as a predictive marker for LRE in patients with NAFLD.

Bioactive signalling lipids as drivers of chronic liver diseases

Lipids are important in multiple cellular functions, with most having structural or energy storage roles. However, a small fraction of lipids exert bioactive roles through binding to G protein-coupled receptors and induce a plethora of processes including cell proliferation, differentiation, growth, migration, apoptosis, senescence and survival. Bioactive signalling lipids are potent modulators of metabolism and energy homeostasis, inflammation, tissue repair and malignant transformation. All these events are involved in the initiation and progression of chronic liver diseases. In this review, we focus specifically on the roles of bioactive lipids derived from phospholipids (lyso-phospholipids) and poly-unsaturated fatty acids (eicosanoids, pro-resolving lipid mediators and endocannabinoids) in prevalent chronic liver diseases (alcohol-associated liver disease, non-alcoholic fatty liver disease, viral hepatitis and hepatocellular carcinoma). We discuss the balance between pathogenic and beneficial bioactive lipids as well as potential therapeutic targets related to the agonism or antagonism of their receptors.

A Diagnostic Impact of Serum Autotaxin Levels in Patients with Bone Marrow Fibrosis

BACKGROUND

Bone marrow (BM) fibrosis is a condition characterized by deposition of reticulin and collagen fibers in BM. It may confer a poor prognosis in some of hematological malignancies. However, the relationship between fibrosis and the disease pathology is not fully understood and no biomarkers for BM fibrosis are available in clinical practice. Autotaxin (ATX) is a secreted enzyme that is associated with various pathophysiological responses, including fibrosis. We conducted a pilot study to investigate the serum ATX levels in various hematological disorders in patients with or without BM fibrosis.

PATIENTS AND METHODS

The serum levels of ATX in a total of 198 patients with hematological disorders and 160 healthy subjects were analyzed. Because of sexual difference in ATX level, the ATX ratio-determined by dividing the ATX level by the mean value of ATX of control subjects of the same sex-was calculated for further comparative analysis. A trephine biopsy samples from 53 patients were also evaluated to determine the Reticulin Fibrosis Index and Collagen Fibrosis Index of each sample.

RESULTS

In comparison to the control group, the ATX ratio was significantly higher in patients, especially those with malignant lymphoma. The ATX ratio in lymphoma patients with BM fibrosis was significantly higher than that in patients without BM fibrosis. The Collagen Fibrosis Index showed statistically significant negative correlation with the ATX ratio.

CONCLUSION

Our results suggest that the ATX ratio may be a candidate diagnostic biomarker for BM fibrosis in selected patients, including those with malignant lymphoma.

Circulating autotaxin levels in healthy teenagers: Data from the Vitados cohort

Autotaxin (ATX) is a secreted enzyme with a lysophospholipase D activity, mainly secreted by adipocytes and widely expressed. Its major function is to convert lysophosphatidylcholine (LPC) into lysophosphatidic acid (LPA), an essential bioactive lipid involved in multiple cell processes. The ATX-LPA axis is increasingly studied because of its involvement in numerous pathological conditions, more specifically in inflammatory or neoplastic diseases, and in obesity. Circulating ATX levels gradually increase with the stage of some pathologies, such as liver fibrosis, thus making them a potentially interesting non-invasive marker for fibrosis estimation. Normal circulating levels of ATX have been established in healthy adults, but no data exist at the pediatric age. The aim of our study is to describe the physiological concentrations of circulating ATX levels in healthy teenagers through a secondary analysis of the VITADOS cohort. Our study included 38 teenagers of Caucasian origin (12 males, 26 females). Their median age was 13 years for males and 14 years for females, ranging from Tanner 1 to 5. BMI was at the 25th percentile for males and 54th percentile for females, and median blood pressure was normal. ATX median levels were 1,049 (450-2201) ng/ml. There was no difference in ATX levels between sexes in teenagers, which was in contrast to the male and female differences described in the adult population. ATX levels significantly decreased with age and pubertal status, reaching adult levels at the end of puberty. Our study also suggested positive correlations between ATX levels and blood pressure (BP), lipid metabolism, and bone biomarkers. However, except for LDL cholesterol, these factors were also significantly correlated with age, which might be a confounding factor. Still, a correlation between ATX and diastolic BP was described in obese adult patients. No correlation was found between ATX levels and inflammatory marker C-reactive protein (CRP), Body Mass Index (BMI), and biomarkers of phosphate/calcium metabolism. In conclusion, our study is the first to describe the decline in ATX levels with puberty and the physiological concentrations of ATX levels in healthy teenagers. It will be of utmost importance when performing clinical studies in children with chronic diseases to keep these kinetics in mind, as circulating ATX might become a non-invasive prognostic biomarker in pediatric chronic diseases.

Decrease in serum levels of autotaxin in COVID-19 patients

INTRODUCTION

In order to identify therapeutic targets in Coronavirus disease 2019 (COVID-19), it is important to identify molecules involved in the biological responses that are modulated in COVID-19. Lysophosphatidic acids (LPAs) are involved in the pulmonary inflammation and fibrosis are one of the candidate molecules. The aim of this study was to evaluate the association between the serum levels of autotaxin (ATX), which are enzymes involved in the synthesis of lysophosphatidic acids.

MATERIAL AND METHODS

We enrolled 134 subjects with COVID-19 and 58 normal healthy subjects for the study. We measured serum ATX levels longitudinally in COVID-19 patients and investigated the time course and the association with severity and clinical parameters.

RESULTS

The serum ATX levels were reduced in all patients with COVID-19, irrespective of the disease severity, and were negatively associated with the serum CRP, D-dimer, and anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody levels.

DISCUSSION

Considering the biological properties of LPAs in the pulmonary inflammation and fibrosis, modulation of ATX might be compensatory biological responses to suppress immunological overreaction especially in the lung, which is an important underlying mechanism for the mortality of the disease.

CONCLUSIONS

COVID-19 patients showed a decrease in the serum levels of ATX, irrespective of the disease severity. Key MessagesAutotaxin (ATX) is an enzyme involved in the synthesis of lysophosphatidic acid (LPA), which has been reported to be involved in pulmonary inflammation and fibrosis. Patients with COVID-19 show decrease in the serum levels of ATX. Modulation of ATX might be compensatory biological responses to suppress immunological overreaction.

Circulating thrombospondin 2 levels reflect fibrosis severity and disease activity in HCV-infected patients

Among several secreted glycoproteins belonging to the thrombospondin family, thrombospondin 2 (TSP2) is involved in various functions, including collagen/fibrin formation. Liver/serum TSP2 levels have been correlated to liver fibrosis stage and disease activity in nonalcoholic fatty liver disease. This study investigated whether serum TSP2 was associated with clinicopathological features in hepatitis C virus (HCV)-infected patients as well. A total of 350 patients with HCV who had undergone liver biopsy were retrospectively enrolled and divided into a discovery cohort (n = 270) and a validation cohort (n = 80). In the discovery cohort, serum TSP2 levels were moderately correlated with both liver fibrosis stage (r = 0.426, P < 0.0001) and activity grade (r = 0.435, P < 0.0001). The area under the receiver operating characteristic curve of TSP2 for predicting severe fibrosis (≥ F3) was 0.78 and comparable to or better than those of autotaxin (0.78), FIB-4 index (0.78), and APRI (0.76). The discovery cohort findings were closely replicated in the validation cohort. Moreover, comprehensive liver genetic analysis of HCV-infected patients confirmed that the expression of the THBS2 gene encoding TSP2 was significantly higher in severely fibrotic F4 than in F1 patients. Circulating TSP2 levels may reflect the severity of hepatic fibrosis/inflammation in HCV-infected patients.

Cholestatic Itch: Our Current Understanding of Pathophysiology and Treatments

Hepatic pruritus is common in liver conditions, including cholestasis and nonalcoholic fatty liver disease. The pruritus can be severe enough to diminish sleep and decrease quality of life. The pathophysiology likely involves many molecules and receptors, including bile acids, bilirubin, lysophosphatidic acid (LPA), endogenous opioids, and serotonin. Recent advances suggest a significant role of Mas-related G protein-coupled receptor X4 (MRGPRX4) and autotaxin/LPA as key players in cholestatic pruritus. Further research is needed to develop increasingly targeted therapies with greater efficacy, especially given that many patients report itch refractory to various treatments. Cholestyramine was the only US FDA-approved drug for cholestatic pruritus until recent approval of ileal bile acid transporter (IBAT) inhibitors for use in the pediatric cholestatic conditions, progressive familial intrahepatic cholestasis and Alagille syndrome. Both medications decrease the bile acid pool. IBAT inhibitors are under investigation for broader use, and targeting LPA receptors and MRGPR4 are additional attractive options.

A type IV Autotaxin inhibitor ameliorates acute liver injury and nonalcoholic steatohepatitis

The lysophosphatidic acid (LPA) signaling axis is an important but rather underexplored pathway in liver disease. LPA is predominantly produced by Autotaxin (ATX) that has gained significant attention with an impressive number of ATX inhibitors (type I-IV) reported. Here, we evaluated the therapeutic potential of a (yet unexplored) type IV inhibitor, Cpd17, in liver injury. We first confirmed the involvement of the ATX-LPA signaling axis in human and murine diseased livers. Then, we evaluated the effects of Cpd17, in comparison with the classic type I inhibitor PF8380, in vitro, where Cpd17 showed higher efficacy. Thereafter, we characterized the mechanism-of-action of both inhibitors and found that Cpd17 was more potent in inhibiting RhoA-mediated cytoskeletal remodeling, and phosphorylation of MAPK/ERK and AKT/PKB. Finally, the therapeutic potential of Cpd17 was investigated in CCl₄ -induced acute liver injury and diet-induced nonalcoholic steatohepatitis, demonstrating an excellent potential of Cpd17 in reducing liver injury in both disease models in vivo. We conclude that ATX inhibition, by type IV inhibitor in particular, has an excellent potential for clinical application in liver diseases.

Long-term prediction of hepatocellular carcinoma using serum autotaxin levels after antiviral therapy for hepatitis C

INTRODUCTION AND OBJECTIVES

Continuous monitoring for hepatocellular carcinoma is necessary following treatment with direct-acting antivirals in patients with hepatitis C virus infection. We investigated whether the long-term follow-up of serum autotaxin levels could predict the development of hepatocellular carcinoma.

PATIENTS AND METHODS

This prospective observational study enrolled adult patients with chronic hepatitis C virus infection who presented to the study center from January 2016 to March 2021. Among the patients who achieved a sustained viral response, the relationship between the development of hepatocellular carcinoma and serum autotaxin levels was assessed before treatment with direct-acting antivirals; at the end of therapy; at 12 and 24 weeks; and at 12, 24, 36, and 48 months after treatment.

RESULTS

Data were analyzed for 139 patients. Thirteen patients developed hepatocellular carcinoma 48 months after treatment. The cut-off serum autotaxin values that predicted hepatocellular carcinoma after 24 weeks were 1.22 (men) and 1.92 (women) mg/L. The area under the curve for serum autotaxin was 0.83 (95% confidence interval [CI]:0.71-0.95) in men and 0.90 (95% CI: 0.82-0.99) in women. The positive predictive value of serum autotaxin was 0.208 (95% CI: 0.139-0.248), and the negative predictive value was 0.971 (95% CI: 0.939-0.990). The cumulative incidence of hepatocellular carcinoma was significantly higher when serum autotaxin levels were above the cut-off value after 24 weeks (p < 0.0001).

CONCLUSIONS

Serum autotaxin is a candidate biomarker for predicting hepatocellular carcinoma during the long-term follow-up of patients with a sustained viral response following treatment with direct-acting antivirals.

Structure and function of the Ecto-Nucleotide Pyrophosphatase-Phosphodiesterase (ENPP) family: tidying up diversity

Ecto-nucleotide pyrophosphatase/phosphodiesterase (ENPP) family members (ENPP1–7) have been implicated in key biological and pathophysiological processes, including nucleotide and phospholipid signaling, bone mineralization, fibrotic diseases, and tumor-associated immune cell infiltration. ENPPs are single-pass transmembrane ecto-enzymes, with notable exceptions of ENPP2 (Autotaxin) and ENNP6, which are secreted and glycosylphosphatidylinositol (GPI)-anchored, respectively. ENNP1 and ENNP2 are the best characterized and functionally the most interesting members. Here, we review the structural features of ENPP1–7 to understand how they evolved to accommodate specific substrates and mediate different biological activities. ENPPs are defined by a conserved phosphodiesterase (PDE) domain. In ENPP1–3, the PDE domain is flanked by two N-terminal somatomedin B-like domains and a C-terminal inactive nuclease domain that confers structural stability, whereas ENPP4–7 only possess the PDE domain. Structural differences in the substrate-binding site endow each protein with unique characteristics. Thus, ENPP1, ENPP3, ENPP4, and ENPP5 hydrolyze nucleotides, whereas ENPP2, ENPP6, and ENNP7 evolved as phospholipases through adaptions in the catalytic domain. These adaptations explain the different biological and pathophysiological functions of individual members. Understanding the ENPP members as a whole advances our insights into common mechanisms, highlights their functional diversity, and helps to explore new biological roles.

Impact of serum autotaxin level correlating with histological findings in biliary atresia

PURPOSE

Portoenterostomy is the standard treatment for biliary atresia (BA) that reduces jaundice in two thirds of cases. However, progressive liver fibrosis is common, leading to cirrhosis in most patients. Autotaxin is a new marker for the progression of hepatic fibrosis. We examined the relationship between serum autotaxin levels and liver histological findings in patients with BA.

METHODS

BA patients with native livers were identified in our hospital. Patients underwent protocol liver biopsies every 1 to 5 years, and liver fibrosis was evaluated based on the METAVIR score. Serum autotaxin levels were compared with the last available pathological findings.

RESULTS

Thirty-five patients were included and the median age was 10.6 years. Serum autotaxin levels was median 1.6 mg/L. The mean autotaxin level was 1.08 mg/L in F0, 1.07 mg/L in F1, 0.95 mg/L in F2, 2.17 mg/L in F3, and 2.50 mg/L in F4; it was significantly higher in F4 than in F0-F2 (P<0.0024). For predicting cirrhosis (F4) and advanced liver fibrosis (≥F3), autotaxin had the almost same areas under the curve (AUCs 0.78 and 0.90, respectively) as well as M2BPGi.

CONCLUSION

Autotaxin levels could be used to evaluate the status of native liver fibrosis.

Hepatoprotective effect of Saccharomyces Cervisciae Cell Wall Extract against thioacetamide-induced liver fibrosis in rats

Fibrosis represents a common outcome of almost all chronic liver diseases and leads to an impairment of liver function that requires medical intervention. The current study aimed to evaluate the potential anti-fibrotic effect of Saccharomyces cervisciae cell wall extract (SCCWE) against thioacetamide (TAA)-induced liver fibrosis in rats (200mg/kg b.w. i.p. twice weekly for 6 weeks) using Ursodeoxycholic acid (UDCA) as a reference anti-fibrotic product. SCCWE at two doses (50 and 100 mg/kg) significantly ameliorated the rise in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma glutamide transferase (GGT) activities, total bilirubin and direct bilirubin, increased total protein and albumin. SCCWE significantly reduced glutathione depletion (GSH), Nitric oxide (NOx) and malondialdehyde (MDA), thioredoxin (Trx) contents and elevated nuclear factor erythroid 2–related factor 2 (Nrf-2) content. Its anti-inflammatory effects were confirmed by observing a decrease in nuclear factor-κB (NF- κβ), interleukin-1b (IL-1β) and inducible nitric oxide synthase (iNOS) content. The anti-fibrotic effects of SCCWE were explored by assessing fibrosis related markers as it significantly reduced transform growth factor-β (TGF-β) and autotaxin (ATX) contents. Administration of SCCWE significantly decreased matrix metalloproteinase-3 and 9 (MMP-3 and -9). Furthermore, it also decreased alpha smooth muscle actin (α-SMA) and caspase-3 as assessed immunohistochemically those results were similar to that of the standard drug UDCA. This study shows that SCCWE protects against TAA-induced liver fibrosis in rats, through attenuating oxidative stress, and inflammation, ameliorating MMPs, combating apoptosis and thereby fibrotic biomarkers in addition to improving histopathological changes.

Integrating Spatial Transcriptomics and Single-Cell RNA-seq Reveals the Gene Expression Profling of the Human Embryonic Liver

The liver is one of vital organs of the human body, and it plays an important role in the metabolism and detoxification. Moreover, fetal liver is one of the hematopoietic places during ontogeny. Understanding how this complex organ develops during embryogenesis will yield insights into how functional liver replacement tissue can be engineered and how liver regeneration can be promoted. Here, we combine the advantages of single-cell RNA sequencing and Spatial Transcriptomics (ST) technology for unbiased analysis of fetal livers over developmental time from 8 post-conception weeks (PCW) and 17 PCW in humans. We systematically identified nine cell types, and defined the developmental pathways of the major cell types. The results showed that human fetal livers experienced blood rapid growth and immigration during the period studied in our experiments, and identified the differentially expressed genes, and metabolic changes in the developmental process of erythroid cells. In addition, we focus on the expression of liver disease related genes, and found that 17 genes published and linked to liver disease mainly expressed in megakaryocyte and endothelial, hardly expressed in any other cell types. Together, our findings provide a comprehensive and clear understanding of the differentiation processes of all main cell types in the human fetal livers, which may provide reference data and information for liver disease treatment and liver regeneration.

Review of Diagnostic Biomarkers in Autoimmune Pancreatitis: Where Are We Now?

Autoimmune pancreatitis (AIP) is a pancreatic manifestation of an IgG4-related disease (IgG4-RD). AIP lacks disease-specific biomarkers, and therefore, it is difficult to distinguish AIP from malignancies, especially pancreatic cancer. In this review, we have summarized the latest findings on potential diagnostic biomarkers for AIP. Many investigations have been conducted, but no specific biomarkers for AIP are identified. Therefore, further studies are required to identify accurate diagnostic biomarkers for AIP.

Clinical Usefulness of Serum Autotaxin for Early Prediction of Relapse in Male Patients with Type 1 Autoimmune Pancreatitis

BACKGROUND

Serum IgG4 level is a useful diagnostic marker for autoimmune pancreatitis (AIP), but it is difficult to use to predict relapse.

AIMS

We investigated whether serum autotaxin (ATX) level is predictive of AIP relapse after steroid therapy.

METHODS

Fifty-six patients with type 1 AIP were investigated. We measured serum ATX at the time of diagnosis. We selected 24 males for whom serum samples during steroid therapy had been obtained and measured serum ATX at steroid therapy for induction of remission and at maintenance therapy. In the relapse group, we also measured ATX at the time of relapse.

RESULTS

ATX was significantly higher in female patients than in male patients. In order to clarify changes in ATX during steroid therapy, we focused on 24 male patients. We found that ATX decreased significantly during steroid therapy for induction of remission and at the time of maintenance therapy. In half of all patients who relapsed during maintenance therapy, ATX was significantly elevated at the time of relapse compared with that of induction therapy (P = 0.039). When we compared ATX at the time of maintenance therapy between patients with relapse and without, we observed significantly higher ATX in the former (P = 0.024). We found that the combination of ATX and elastase-1 could predict relapse with high accuracy (95%).

CONCLUSIONS

Preliminary evidence suggests that serum ATX might serve as a candidate biomarker to predict relapse of AIP as well as to monitor the effect of steroid therapy.

Cholestasis-Associated Pruritus and Its Pruritogens

Pruritus is a debilitating symptom of various cholestatic disorders, including primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and inherited progressive familial intrahepatic cholestasis (PFIC). The molecular mechanisms leading to cholestasis-associated pruritus are still unresolved and the involved pruritogens are indecisive. As a consequence of pruritus, patients suffer from sleep deprivation, loss of daytime concentration, auto-mutilation and sometimes even suicidal ideations. Current guideline-approved therapy of cholestasis-associated pruritus includes stepwise administration of several medications, which may alleviate complaints in some, but not all affected patients. Therefore, also experimental therapeutic approaches are required to improve patients' quality of life. This article reviews the current state of research on pruritogens and their receptors, and shortly discusses the most recent experimental therapies.

Hepatitis C Virus (HCV) Direct-Acting Antiviral Therapy in Persons With Human Immunodeficiency Virus-HCV Genotype 1 Coinfection Resulting in High Rate of Sustained Virologic Response and Variable in Normalization of Soluble Markers of Immune Activation

BACKGROUND

Hepatitis C virus (HCV) direct-acting antivirals are highly effective. Less is known about changes in markers of immune activation in persons with human immunodeficiency virus (HIV) in whom a sustained virologic response (SVR) is achieved.

METHODS

We conducted a nonrandomized clinical trial of 12 or 24 weeks of paritaprevir-ritonavir-ombitasvir plus dasabuvir (PrOD) with or without ribavirin in persons with HCV-1/HIV coinfection suppressed with antiretroviral therapy. Plasma HCV, soluble CD14 (sCD14), interferon-inducible protein 10, soluble CD163 (sCD163), interleukin 6 (IL-6), interleukin 18, monocyte chemoattractant protein (MCP-1), autotaxin (ATX), and Mac2-binding protein (Mac2BP) were measured over 48 weeks.

RESULTS

Participants were treated with PrOD for 12 (n = 9) or 24 (n = 36) weeks; the SVR rate at 12 weeks was 93%. At baseline, cirrhosis was associated with higher ATX and MCP-1, female sex with higher ATX and IL-6, older age with higher Mac2BP, higher body mass index with higher ATX, and HIV-1 protease inhibitor use with higher sCD14 levels. In those with SVR, interferon-inducible protein 10, ATX, and Mac2BP levels declined by week 2, interleukin 18 levels declined by the end of treatment, sCD14 levels did not change, and sCD163, MCP-1, and IL-6 levels changed at a single time point.

CONCLUSIONS

During HIV/HCV coinfection, plasma immune activation marker heterogeneity is in part attributable to age, sex, cirrhosis, body mass index, and/or type of antiretroviral therapy. HCV treatment with paritaprevir-ritonavir-ombitasvir plus dasabuvir is highly effective and is associated with variable rate and magnitude of decline in markers of immune activation.

CLINICAL TRIALS REGISTRATION

NCT02194998.

Association of serum autotaxin levels with liver fibrosis in patients pretreatment and posttreatment with chronic hepatitis C

BACKGROUND AND AIM

The evaluation of liver fibrosis in patients with chronic hepatitis C virus (HCV) infection is important as it is a risk factor for hepatocellular carcinoma. In the recent years, autotaxin (ATX) has been established as a new noninvasive biomarker to predict liver fibrosis. However, antiviral treatment has been reported to decrease serum ATX, but it is unclear whether posttreatment ATX levels reflect liver fibrosis. In the present study, the correlation between ATX and liver fibrosis in pretreatment and posttreatment patients with HCV infection was analyzed.

METHODS

A total of 199 samples from 136 patients with HCV infection who had undergone hepatic biopsy before and/or after antiviral treatment at Osaka City University Hospital were used. Posttreatment patients included 38 interferon-treated patients and 80 interferon-free direct-acting antiviral-treated patients; all patients achieved a sustained virological response (SVR). Serum ATX levels were determined by enzyme immunoassay with an AIA-2000 analyzer.

RESULTS

Serum ATX levels were largely correlated with liver fibrosis stage in patients with HCV infection before and after antiviral treatment. The measured values decreased even in similar liver fibrosis stages after treatment. The area under the receiver operating characteristic curve for the ability of ATX to diagnose above F2 stage before treatment was 0.81 (both male and female) and that after achieving SVR, it was 0.71 (male) and 0.72 (female).

CONCLUSIONS

Serum ATX levels were correlated with histological liver fibrosis stage after achieving SVR. However, separate cutoff values before and after antiviral therapy should be established.

Serum autotaxin levels in responders to HCV treatment by direct-acting antivirals

Background

Hepatitis C virus (HCV) infection is considered one of the main causes of chronic liver disease around the world. Liver biopsy has been believed to be the gold standard for the assessment of the degree of liver fibrosis. Thus, there is a need to improve non-invasive evaluation of liver fibrosis. The aim of the present study was to study the changes in serum levels of ATX (Autotaxin) as a marker of hepatic fibrosis in responders to HCV treatment by DAAs. This prospective study was carried out at hepatology outpatient clinics for HCV treatment in Mansoura Specialized Medical Hospital that involved 54 participants: 34 patients with HCV and 20 controls; ATX was measured for the controls and all patients before and after treatment.

Results

We found a significant higher ATX level in control subjects vs HCV patients, 100% of control subjects had ATX > 97.5 and 58.8% of HCV had ATX ≤ 97.5. Also, a significantly higher ATX after treatment with DAAs as a whole was observed.

Conclusion

The authors concluded that ATX should be considered cautiously as a diagnostic marker for liver fibrosis in Egyptian patients with chronic hepatitis C infection. Although this study yielded negative results, this may be important to prevent duplication of the research efforts.

The impact of achieving a sustained virological response with direct-acting antivirals on serum autotaxin levels in chronic hepatitis C patients

Background

Autotaxin (ATX) is an emerging biomarker for liver fibrosis. Achievement of sustained virological response (SVR) by direct-acting antivirals (DAAs) results in hepatic fibrosis regression in chronic hepatitis C (CHC) patients. In this context, the clinical implications of ATX have not yet been well-defined. In this study, we aimed to assess the impact of achieving SVR with DAA therapy on serum ATX levels and whether these levels can reflect the regression of hepatic fibrosis in CHC patients. We evaluated serum ATX levels at baseline and 12 weeks post-DAA therapy in 48 CHC patients. We compared ATX with FIB4 score and AST-to-Platelet Ratio Index (APRI) as regards the detection of grade F3–4 fibrosis.

Results

Serum ATX levels were significantly declined in 47 patients after the achievement of SVR12 (p < 0.001). The diagnostic ability of ATX for the detection of grade F3–4 fibrosis was inferior to FIB4 and APRI scores at baseline and SVR12.

Conclusion

Achievement of SVR with DAA therapy causes a significant decline in serum autotaxin concentrations, suggesting early regression of hepatic fibrosis in CHC patients. However, its diagnostic capability for routine patient monitoring and follow-up is still under debate.

Post-Treatment M2BPGi Level and the Rate of Autotaxin Reduction are Predictive of Hepatocellular Carcinoma Development after Antiviral Therapy in Patients with Chronic Hepatitis C

Patients with chronic hepatitis C virus (HCV) develop hepatocellular carcinoma (HCC) regardless of achieving a sustained viral response (SVR). Because advanced liver fibrosis is a powerful risk factor for HCC, we analyzed the association between autotaxin (ATX), a liver fibrosis marker, and post-SVR HCC development within 3 years after antiviral treatment. We included 670 patients with HCV who received direct-acting antivirals, achieved SVR and were followed up for at least 6 months (270 of them were followed up for 3 years or more). We measured serum ATX levels before treatment and 12/24 weeks after treatment. The diagnosis of HCC was based on imaging modalities, such as dynamic computed tomography and dynamic magnetic resonance imaging and/or liver biopsy. The present study revealed that high levels of serum ATX predicted post-SVR HCC development (area under the receiver operating characteristic: 0.70-0.76). However, Wisteria floribunda agglutinin positive Mac-2 binding protein (M2BPGi), another liver fibrosis marker, was a more useful predictive marker especially post-treatment according to a multivariate analysis. Patients with a high rate of ATX reduction before and after antiviral treatment did not develop HCC regardless of high pretreatment ATX levels. In conclusion, post-treatment M2BPGi level and the combination of pretreatment ATX levels and rate of ATX reduction were useful predictive markers for post-SVR HCC development in patients with chronic HCV infection.

Clinical impact of normal alanine aminotransferase on direct-acting antiviral outcome in patients with chronic hepatitis C virus infection

Background and Aims

This study aimed to clarify the clinical picture of hepatitis C virus (HCV) carriers with normal alanine aminotransferase (CNALT) and those with ALT elevation (non‐CNALT) under direct‐acting antivirals (DAAs).

Methods

We enrolled 1002 patients with HCV (427 men, median age: 69 years) who had received DAAs for comparisons between CNALT (ALT ≤33 U/L in males and ≤25 U/L in females; n = 374) and non‐CNALT (n = 628) groups.

Results

CNALT patients displayed a higher platelet count (PLT) (170 000 vs 146 000/μL, P < 0.0001) and albumin (4.1 vs 4.1 g/dL, P = 0.0006) but lower AST (25 vs 51 U/L, P < 0.0001), alpha fetoprotein (3.2 vs 5.4 ng/mL, P < 0.0001), and liver fibrosis marker scores (all P < 0.0001). The sustained virologic response rate was comparable between the CNALT and non‐CNALT groups (97.8 vs 95.3%, P = 0.106). The cumulative incidence of hepatocellular carcinoma (HCC) after DAA treatment was comparable between the CNALT and non‐CNALT groups (P = 0.117, log‐rank test). In CNALT patients with HCC history, PLT ≥150 000/μL was an independent risk factor of HCC recurrence (P = 0.019). In non‐CNALT patients without HCC history, male gender (P = 0.021) and albumin <4.0 g/dL (P = 0.007) were independent risk factors, while PLT < 150 000/μL (P = 0.081) was a marginal risk factor of HCC occurrence.

Conclusion

CNALT patients displayed a milder degree of liver fibrosis. Combinations of CNALT and PLT status might be useful as markers for HCC occurrence or recurrence surveillance.

Metabolic Hallmarks of Hepatic Stellate Cells in Liver Fibrosis

Liver fibrosis is a regenerative process that occurs after injury. It is characterized by the deposition of connective tissue by specialized fibroblasts and concomitant proliferative responses. Chronic damage that stimulates fibrogenic processes in the long-term may result in the deposition of excess matrix tissue and impairment of liver functions. End-stage fibrosis is referred to as cirrhosis and predisposes strongly to the loss of liver functions (decompensation) and hepatocellular carcinoma. Liver fibrosis is a pathology common to a number of different chronic liver diseases, including alcoholic liver disease, non-alcoholic fatty liver disease, and viral hepatitis. The predominant cell type responsible for fibrogenesis is hepatic stellate cells (HSCs). In response to inflammatory stimuli or hepatocyte death, HSCs undergo trans-differentiation to myofibroblast-like cells. Recent evidence shows that metabolic alterations in HSCs are important for the trans-differentiation process and thus offer new possibilities for therapeutic interventions. The aim of this review is to summarize current knowledge of the metabolic changes that occur during HSC activation with a particular focus on the retinol and lipid metabolism, the central carbon metabolism, and associated redox or stress-related signaling pathways.

Elevated Autotaxin and LPA Levels During Chronic Viral Hepatitis and Hepatocellular Carcinoma Associate with Systemic Immune Activation

Circulating autotaxin (ATX) is elevated in persons with liver disease, particularly in the setting of chronic hepatitis C virus (HCV) and HCV/HIV infection. It is thought that plasma ATX levels are, in part, attributable to impaired liver clearance that is secondary to fibrotic liver disease. In a discovery data set, we identified plasma ATX to be associated with parameters of systemic immune activation during chronic HCV and HCV/HIV infection. We and others have observed a partial normalization of ATX levels within months of starting interferon-free direct-acting antiviral (DAA) HCV therapy, consistent with a non-fibrotic liver disease contribution to elevated ATX levels, or HCV-mediated hepatocyte activation. Relationships between ATX, lysophosphatidic acid (LPA) and parameters of systemic immune activation will be discussed in the context of HCV infection, age, immune health, liver health, and hepatocellular carcinoma (HCC).

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

Background

Pruritus 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.

Methods

A 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.

Results

The 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.

Conclusion

The 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.

Deregulated Lysophosphatidic Acid Metabolism and Signaling in Liver Cancer

Liver cancer is one of the leading causes of death worldwide due to late diagnosis and scarcity of treatment options. The major risk factor for liver cancer is cirrhosis with the underlying causes of cirrhosis being viral infection (hepatitis B or C), metabolic deregulation (Non-alcoholic fatty liver disease (NAFLD) in the presence of obesity and diabetes), alcohol or cholestatic disorders. Lysophosphatidic acid (LPA) is a bioactive phospholipid with numerous effects, most of them compatible with the hallmarks of cancer (proliferation, migration, invasion, survival, evasion of apoptosis, deregulated metabolism, neoangiogenesis, etc.). Autotaxin (ATX) is the enzyme responsible for the bulk of extracellular LPA production, and together with LPA signaling is involved in chronic inflammatory diseases, fibrosis and cancer. This review discusses the most important findings and the mechanisms related to ATX/LPA/LPAR involvement on metabolic, viral and cholestatic liver disorders and their progression to liver cancer in the context of human patients and mouse models. It focuses on the role of ATX/LPA in NAFLD development and its progression to liver cancer as NAFLD has an increasing incidence which is associated with the increasing incidence of liver cancer. Bearing in mind that adipose tissue accounts for the largest amount of LPA production, many studies have implicated LPA in adipose tissue metabolism and inflammation, liver steatosis, insulin resistance, glucose intolerance and lipogenesis. At the same time, LPA and ATX play crucial roles in fibrotic diseases. Given that hepatocellular carcinoma (HCC) is usually developed on the background of liver fibrosis, therapies that both delay the progression of fibrosis and prevent its development to malignancy would be very promising. Therefore, ATX/LPA signaling appears as an attractive therapeutic target as evidenced by the fact that it is involved in both liver fibrosis progression and liver cancer development.

Autotaxin is a valuable biomarker for the prediction of liver fibrosis in patients with non-alcoholic fatty liver disease

AIM

We investigated the characteristics of serum autotaxin (ATX) and its diagnostic performance for liver fibrosis in a large cohort of patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

We compared the usefulness of ATX and other fibrosis markers in 307 biopsy-confirmed NAFLD patients. In addition, in 145 participants with NAFLD, we compared the diagnostic performance of ATX with that of non-invasive imaging methods (vibration-controlled transient elastography and magnetic resonance elastography [MRE]).

RESULTS

Serum ATX concentration was significantly correlated with fibrosis stage in male and female NAFLD patients. In male patients, the area under the receiver operating characteristic (AUROC) curve values of ATX for the diagnosis of ≥stage 1, ≥stage 2, ≥stage 3, and ≥stage 4 fibrosis were 0.65, 0.75, 0.81, and 0.95, respectively. In female NAFLD participants, the AUROC values were all >0.81. The sensitivity of ATX was highest for the diagnosis of ≥stage 2 and ≥stage 3 fibrosis in both men and women with NAFLD. In the comparison between ATX and non-invasive imaging methods, the AUROC for MRE was the highest at every stage of fibrosis.

CONCLUSIONS

Serum ATX concentration is significantly correlated with fibrosis stage in NAFLD patients. The diagnostic accuracy of ATX for liver fibrosis is lower than that of MRE, but the sensitivities of ATX for the diagnosis of ≥stage 2 and ≥stage 3 were highest. We conclude that ATX is useful for the selection of patients requiring further evaluation for liver fibrosis.

Lysophosphatidic Acid Induces ECM Production via Activation of the Mechanosensitive YAP/TAZ Transcriptional Pathway in Trabecular Meshwork Cells

Purpose

Lysophosphatidic acid (LPA), a bioactive lipid, has been shown to increase resistance to aqueous humor outflow (AH) through the trabecular meshwork (TM). The molecular basis for this response of the TM to LPA, however, is not completely understood. In this study, we explored the possible involvement of mechanosensitive Yes-associated protein (YAP) and its paralog, transcriptional coactivator with PDZ-binding domain (TAZ), transcriptional activation in extracellular matrix (ECM) production by LPA-induced contractile activity in human TM cells (HTM).

Methods

The responsiveness of genes encoding LPA receptors (LPARs), LPA hydrolyzing lipid phosphate phosphatases (LPPs), and the LPA-generating autotaxin (ATX) to cyclic mechanical stretch in HTM cells, was evaluated by RT-quantitative (q)PCR. The effects of LPA and LPA receptor antagonists on actomyosin contractile activity, activation of YAP/TAZ, and levels of connective tissue growth factor (CTGF), and Cyr61 and ECM proteins in HTM cells were determined by immunoblotting, mass spectrometry, and immunofluorescence analyses.

Results

Cyclic mechanical stretch significantly increased the expression of several types of LPARs, LPP1, and ATX in HTM cells. LPA and LPA receptor–dependent contractile activity led to increases in both, the protein levels and activation of YAP/TAZ, and increased the levels of CTGF, Cyr61, α-smooth muscle actin (α–SMA), and ECM proteins in HTM cells.

Conclusions

The results of this study reveal that LPA and its receptors stimulate YAP/TAZ transcriptional activity in HTM cells by modulating cellular contractile tension, and augment expression of CTGF that in turn leads to increased production of ECM. Therefore, YAP/TAZ-induced increases in CTGF and ECM production could be an important molecular mechanism underlying LPA-induced resistance to AH outflow and ocular hypertension.

Past history of hepatocellular carcinoma is an independent risk factor of treatment failure in patients with chronic hepatitis C virus infection receiving direct-acting antivirals

Direct-acting antiviral (DAA) treatment can achieve a high sustained virological response (SVR) rate in patients with hepatitis C virus (HCV) infection regardless of a history of hepatocellular carcinoma (HCC [+]). We examined 838 patients (370 men, median age: 69 years) who were treated with DAAs for comparisons of clinical findings between 79 HCC (+) (9.4%) and 759 HCC (-) (90.6%) patients and associations with treatment outcome. Male frequency was significantly higher in the HCC (+) group (60.8% vs 42.4%, P = 0.006). There were significant differences between the HCC (+) and HCC (-) groups for platelet count (115 vs 152 ×10⁹ /L, P < 0.001), baseline alpha fetoprotein (AFP) (9.9 vs 4.5 ng/mL, P < 0.001) and the established fibrosis markers of FIB-4 index (4.7 vs 3.0, P < 0.001), AST-to-platelet ratio index (APRI) (1.1 vs 0.7, P = 0.009), M2BPGi (3.80 vs 1.78 COI, P < 0.001) and autotaxin (1.91 vs 1.50 mg/L, P < 0.001). The overall SVR rate was 94.7% and significantly lower in the HCC (+) group (87.3 vs 95.5%, P = 0.001). Multivariate analysis revealed that a history of HCC was independently associated with DAA treatment failure (odds ratio: 3.56, 95% confidence interval: 1.32-9.57, P = 0.01). In conclusion, patients with chronic HCV infection and prior HCC tended to exhibit more advanced disease progression at DAA commencement. HCC (+) status at the initiation of DAAs was significantly associated with adverse therapeutic outcomes. DAA treatment for HCV should therefore be started as early as possible, especially before complicating HCC.

Development and therapeutic potential of autotaxin small molecule inhibitors: From bench to advanced clinical trials

Several years after its isolation from melanoma cells, an increasing body of experimental evidence has established the involvement of Autotaxin (ATX) in the pathogenesis of several diseases. ATX, an extracellular enzyme responsible for the hydrolysis of lysophosphatidylcholine (LPC) into the bioactive lipid lysophosphatidic acid (LPA), is overexpressed in a variety of human metastatic cancers and is strongly implicated in chronic inflammation and liver toxicity, fibrotic diseases, and thrombosis. Accordingly, the ATX-LPA signaling pathway is considered a tractable target for therapeutic intervention substantiated by the multitude of research campaigns that have been successful in identifying ATX inhibitors by both academia and industry. Furthermore, from a therapeutic standpoint, the entry and the so far promising results of the first ATX inhibitor in advanced clinical trials against idiopathic pulmonary fibrosis (IPF) lends support to the viability of this approach, bringing it to the forefront of drug discovery efforts. The present review article aims to provide a comprehensive overview of the most important series of ATX inhibitors developed so far. Special weight is lent to the design, structure activity relationship and mode of binding studies carried out, leading to the identification of advanced leads. The most significant in vitro and in vivo pharmacological results of these advanced leads are also summarized. Lastly, the development of the first ATX inhibitor entered in clinical trials accompanied by its phase 1 and 2a clinical trial data is disclosed.

Quantitative analysis of serum chemokines associated with treatment failure of direct-acting antivirals in chronic hepatitis C

Although serum chemokine levels have been reported to influence the outcome of interferon-based treatment in patients with chronic hepatitis C, their effect on the hepatitis C virus (HCV) response to direct-acting antiviral agents (DAAs), which can achieve high rates of a sustained virological response (SVR), is largely unknown. To clarify this relationship, 9 chemokines (eotaxin, GRO-α, IL-8, IP-10, MCP-1, MIP-1α, MIP-1β, RANTES, and SDF-1α) were quantified before, during, and after DAA treatment using serum samples obtained from 57 patients with chronic hepatitis C. All baseline median chemokine levels were significantly higher in patients with chronic hepatitis C than in healthy subjects (P < 0.05). In particular, lower MIP-1β (≤71.5 pg/mL) and higher RANTES (>671.5 pg/mL) levels were significantly associated with patients who failed to clear HCV RNA (P = 0.0039 and 0.013, respectively). Prediction of a clinical response based on a combination of these chemokines demonstrated high sensitivity (82%), specificity (85%), negative predictive value (95%), and area under the curve (0.833). The non-SVR rate (56.3%; 9 of 16) was significantly higher in patients with low MIP-1β and high RANTES compared with other combinations. Moreover, baseline MIP-1β and RANTES were both additive and independent for predicting a non-SVR. Apart from an increase in eotaxin, all chemokines became decreased in patients with a SVR. In conclusion, a combination of serum MIP-1β and RANTES levels may be predictive of a treatment response to DAAs in Japanese patients with chronic hepatitis C.

Soluble Markers of Immune Activation Differentially Normalize and Selectively Associate with Improvement in AST, ALT, Albumin, and Transient Elastography During IFN-Free HCV Therapy

Background

During chronic hepatitis C virus (HCV) infection, Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT) levels mark active liver inflammation and tissue damage, while albumin reflects synthetic liver function and nutritional status. Transient Elastography (TE) is a clinical measure of liver stiffness that facilitates evaluation of liver damage stage. While a portion of the TE score is attributable to liver fibrosis and relatively irreversible damage, another component of the TE score is attributable to liver inflammation or edema. Markers of inflammation during chronic HCV infection include soluble markers of immune activation, which are also associated with morbid outcome (including cardiovascular disease and liver-disease progression). Whether soluble markers of immune activation or changes in their level during HCV therapy relate to normalization of AST, ALT, Albumin, or TE score, is not clear.

Methods

We evaluated soluble markers of immune activation (plasma sCD14, IL-6, sCD163, autotaxin [ATX], and Mac2BP) and TE score, and their relationship in 20 HCV-infected patients before, during, and after HCV-directed IFN-free direct-acting antiviral (DAA) therapy. We evaluated normalization of parameters and the relationship between each over a 6-month window.

Results

Before therapy, serum AST levels positively correlated with plasma levels of sCD14, sCD163, and Mac2BP, while ALT levels positively correlated with Mac2BP. Serum albumin level negatively correlated with plasma IL-6 and ATX levels. IFN-free therapy uniformly resulted in sustained virological response at 12 and 24 weeks after therapy completion. After initiation of therapy AST and ALT normalized, while levels of ATX, Mac2BP, sCD163, and TE score partially normalized over 6 months. Additionally, change in AST level and APRI score correlated with change in sCD163, IL-6, and Mac2BP levels, and change in ALT correlated with change in IL-6 and Mac2BP levels. Improvement in TE score correlated with a decrease in the level of sCD14 at week 4, and almost statistically significant with decrease in sCD14 at weeks 20-24 after initiation of IFN-free HCV therapy.

Conclusions

Soluble markers of immune activation normalize or partially normalize at different rates after initiation of curative HCV DAA therapy, and TE scores improve, with wide variability in the degree of absolute improvement in liver stiffness from patient to patient. Decline magnitude of sCD14 was associated with improvement in TE score, while magnitude of improvement in AST correlated with reduction in sCD163 levels. These data provide support for a model where monocyte/Kupffer cell activation may account for a portion of the liver inflammation and edema, which is at least partially reversible following initiation of HCV DAA therapy.

Serum Autotaxin Concentrations Reflect Changes in Liver Stiffness and Fibrosis After Antiviral Therapy in Patients with Chronic Hepatitis C

The purpose of this study was to determine whether serum autotaxin concentrations reflect liver stiffness in patients with chronic hepatitis C virus (HCV) treated with direct‐acting antiviral agents. Adult patients with chronic HCV were enrolled from January 2016 to August 2017. Autotaxin concentrations in these patients were compared with those of a control group consisting of healthy individuals. Liver stiffness was determined by transient elastography. The relationship between fibrosis markers and fibrosis scores was evaluated before and after treatment. Data from 155 HCV patients and 56 control subjects were analyzed. Autotaxin concentrations were significantly higher in HCV patients with liver stiffness scores less than or equal to 7.4 kPa versus controls. Autotaxin concentrations at the end of treatment and beyond were significantly lower than those prior to treatment. Pretreatment and posttreatment autotaxin concentrations in male and female patients with liver stiffness scores greater than 14.9 kPa changed significantly (P < 0.01 and P < 0.01, respectively). From the start of treatment to 6 months following treatment, the fibrosis marker/liver stiffness score ratios changed as follows: autotaxin: 0.189 (95% confidence interval [CI]: 0.169‐0.209) to 0.191 (95% CI: 0.166‐0.216; P= 0.88); Wisteria floribundaagglutinin‐positive Mac‐2‐binding protein: 0.294 (95% CI: 0.256‐0.332) to 0.223 (95% CI: 0.191‐0.255; P< 0.001); hyaluronic acid: 19.05 (95% CI: 14.29‐23.81) to 13.92 (95% CI: 11.16‐16.70; P = 0.044); and type IV collagen 7S: 0.560 (95% CI: 0.515‐0.604) to 0.546 (95% CI: 0.497‐0.895; P = 0.052). Conclusion: Autotaxin concentrations reflect liver stiffness before and after antiviral treatment in patients with chronic HCV infection.

Increased aqueous autotaxin and lysophosphatidic acid levels are potential prognostic factors after trabeculectomy in different types of glaucoma

We explored the potential relevance of aqueous lysophosphatidic acid (LPA) and autotaxin (ATX) levels on postoperative outcomes of trabeculectomy, and the effects of ATX on fibrotic response in cultured human conjunctiva fibroblast (HCF) cells. We enrolled 70 glaucomatous eyes which underwent trabeculectomy, and quantified aqueous LPA and ATX. Those eyes were followed up for 12 months, and postoperative filtering blebs were evaluated using anterior segment optical coherence tomography. Also, the ATX-induced fibrotic changes in HCFs and the effects of an ATX inhibitor were assessed. Measured aqueous ATX and LPA levels were significantly different between glaucoma subtypes. In multivariate analyses, aqueous ATX levels were significantly correlated with the presence of needlings at 1, 3, 6 and 12 months after surgery. Exfoliative glaucoma, whose ATX level was significantly high, showed significantly increased numbers of needlings and a lower cumulative success rate without needlings. An in vitro study showed that fibrotic changes were upregulated by ATX treatment in HCFs, which was significantly suppressed by an ATX inhibitor. We presently demonstrate that aqueous ATX may be a prognostic factor affecting the fibrotic response in HCFs and bleb formation, and inhibition of ATX could be a therapeutic target after trabeculectomy.

Serum Autotaxin Is a Useful Disease Progression Marker in Patients with Primary Biliary Cholangitis

Autotaxin (ATX) is a secreted enzyme metabolized by liver sinusoidal endothelial cells that has been associated with liver fibrosis. We evaluated serum ATX values in 128 treatment-naïve, histologically assessed primary biliary cholangitis (PBC) patients and 80 healthy controls for comparisons of clinical parameters in a case-control study. The median ATX concentrations in controls and PBC patients of Nakanuma’s stage I, II, III, and IV were 0.70, 0.80, 0.87, 1.03, and 1.70 mg/L, respectively, which increased significantly with disease stage (r = 0.53, P < 0.0001) as confirmed by Scheuer’s classification (r = 0.43, P < 0.0001). ATX correlated with Wisteria floribunda agglutinin-positive Mac-2 binding protein (M2BPGi) (r = 0.51, P < 0.0001) and fibrosis index based on four factors (FIB-4) index (r = 0.51, P < 0.0001). While ALP and M2BPGi levels had decreased significantly (both P < 0.001) by 12 months of ursodeoxycholic acid treatment, ATX had not (0.95 to 0.96 mg/L) (P = 0.07). We observed in a longitudinal study that ATX increased significantly (P < 0.00001) over 18 years in an independent group of 29 patients. Patients succumbing to disease-related death showed a significantly higher ATX increase rate (0.05 mg/L/year) than did survivors (0.02 mg/L/year) (P < 0.01). ATX therefore appears useful for assessing disease stage and prognosis in PBC.

Changes in serum levels of autotaxin with direct-acting antiviral therapy in patients with chronic hepatitis C

Sustained virological response (SVR) rates have increased remarkably since the introduction of direct-acting antiviral agents (DAAs) for chronic hepatitis C. Autotaxin (ATX) is a secreted enzyme converting lysophosphatidylcholine to lysophosphatidic acid and a newly established biomarker for liver fibrosis. Interferon-free DAA regimens for chronic hepatitis C could improve liver stiffness in SVR patients according to several non-invasive evaluation methods, but the clinical response and significance of ATX in this context have not yet been defined. We therefore investigated sequential serum ATX levels at baseline, 4 weeks after the start of treatment, and 24 weeks after treatment in 159 hepatitis C virus (HCV)-infected patients who received DAA therapy. Other non-invasive fibrosis markers (aspartate aminotransferase-to-platelet ratio and FIB-4 index) were examined as well. Baseline median ATX levels were comparable between the 144 patients who achieved a SVR and the 15 who did not (1.54 vs. 1.62 mg/L), but median ATX levels became significantly decreased during and after DAA therapy in the SVR group only (from 1.54 to 1.40 and 1.31 mg/L, respectively; P < 0.001). ATX was significantly decreased between baseline and 4 weeks of treatment in overall, male, and female SVR patients (all P < 0.001). In subjects with low necroinflammatory activity in the liver (i.e., alanine aminotransferase < 30 U/L), ATX levels were significantly reduced from baseline to 4 weeks of treatment and remained low (P < 0.001) in patients with a SVR. Thus, interferon-free DAA therapy was associated with a significant decrease in serum ATX levels in patients achieving a SVR, suggesting early regression of liver fibrosis in addition to inflammation treatment.

Serum autotaxin levels are correlated with hepatic fibrosis and ballooning in patients with non-alcoholic fatty liver disease

AIM

To examine the relationship between serum autotaxin (ATX) concentrations and clinicopathological findings in non-alcoholic fatty liver disease (NAFLD) patients.

METHODS

One hundred eighty-six NAFLD patients who had undergone liver biopsy between 2008 and 2017 were retrospectively enrolled. Serum samples were collected at the time of biopsy and ATX was measured by enzyme immunoassays. Sera obtained from 160 healthy, non-obese individuals were used as controls. Histological findings were graded according to an NAFLD scoring system and correlations with serum ATX were calculated by Spearman’s test. Diagnostic accuracy was evaluated using the area under the receiver operating characteristic curve (AUC). Cut-off values were identified by the Youden index, and the nearest clinically applicable value to the cutoff was considered the optimal threshold for clinical convenience.

RESULTS

Serum ATX levels were significantly higher in NAFLD patients than in controls (0.86 mg/L vs 0.76 mg/L, P < 0.001) and correlated significantly with ballooning score and fibrosis stage (r = 0.36, P < 0.001 and r = 0.45, P < 0.001, respectively). Such tendencies were stronger in female patients. There were no remarkable relationships between ATX and serum alanine aminotransferase, lipid profiles, or steatosis scores. The AUC values of ATX for predicting the presence of fibrosis (≥ F1), significant fibrosis (≥ F2), severe fibrosis (≥ F3), and cirrhosis (F4), were all more than 0.70 in respective analyses.

CONCLUSION

Serum ATX levels may at least partially reflect histological severity in NAFLD.

Coming of Age for Autotaxin and Lysophosphatidate Signaling: Clinical Applications for Preventing, Detecting and Targeting Tumor-Promoting Inflammation

A quarter-century after the discovery of autotaxin in cell culture, the autotaxin-lysophosphatidate (LPA)-lipid phosphate phosphatase axis is now a promising clinical target for treating chronic inflammatory conditions, mitigating fibrosis progression, and improving the efficacy of existing cancer chemotherapies and radiotherapy. Nearly half of the literature on this axis has been published during the last five years. In cancer biology, LPA signaling is increasingly being recognized as a central mediator of the progression of chronic inflammation in the establishment of a tumor microenvironment which promotes cancer growth, immune evasion, metastasis, and treatment resistance. In this review, we will summarize recent advances made in understanding LPA signaling with respect to chronic inflammation and cancer. We will also provide perspectives on the applications of inhibitors of LPA signaling in preventing cancer initiation, as adjuncts extending the efficacy of current cancer treatments by blocking inflammation caused by either the cancer or the cancer therapy itself, and by disruption of the tumor microenvironment. Overall, LPA, a simple molecule that mediates a plethora of biological effects, can be targeted at its levels of production by autotaxin, LPA receptors or through LPA degradation by lipid phosphate phosphatases. Drugs for these applications will soon be entering clinical practice.

Serum autotaxin is a useful liver fibrosis marker in patients with chronic hepatitis B virus infection

AIM

Autotaxin (ATX) is a secreted enzyme that is considered to be associated with liver damage as well as fibrosis. This study assessed the ability of ATX to diagnose liver fibrosis in patients with chronic hepatitis B virus (HBV) infection.

METHODS

Serum ATX levels were retrospectively evaluated in 101 treatment-naïve patients with HBV-related chronic hepatitis or cirrhosis, all of whom had undergone liver biopsy at our hospital.

RESULTS

Serum ATX concentration increased significantly according to liver fibrosis stage in overall (r = 0.46, P < 0.0001), male (r = 0.55, P < 0.0001), and female (r = 0.52, P = 0.0006) patient groups. When analyzed by gender, serum ATX was one of the most reliable markers for all fibrosis stages compared with other tested non-invasive markers, which included hyaluronic acid, type IV collagen 7S, aspartate aminotransferase-to-platelet ratio index, and fibrosis index based on four factors, according to receiver operating characteristic curve analysis.

CONCLUSION

Based on this histologically proven data, ATX represents a novel non-invasive biomarker for liver fibrosis in HBV-infected patients.

Lysophospholipids in laboratory medicine

Lysophospholipids (LPLs), such as lysophosphatidic acid (LPA), sphingosine 1-phosphate (S1P), and lysophosphatidylserine (LysoPS), are attracting attention as second-generation lipid mediators. In our laboratory, the functional roles of these lipid mediators and the mechanisms by which the levels of these mediators are regulated in vivo have been studied. Based on these studies, the clinical introduction of assays for LPLs and related proteins has been pursued and will be described in this review. Although assays of these lipids themselves are possible, autotaxin (ATX), apolipoprotein M (ApoM), and phosphatidylserine-specific phospholipase A₁ (PS-PLA₁) are more promising as alternate biomarkers for LPA, S1P, and LysoPS, respectively. Presently, ATX, which produces LPA through its lysophospholipase D activity, has been shown to be a useful laboratory test for the diagnosis and staging of liver fibrosis, whereas PS-PLA₁ and ApoM are considered to be promising clinical markers reflecting the in vivo actions induced by LysoPS and S1P.

Pathological process of liver sinusoidal endothelial cells in liver diseases

Cirrhosis develops from liver fibrosis and is the severe pathological stage of all chronic liver injury. Cirrhosis caused by hepatitis B virus and hepatitis C virus infection is especially common. Liver fibrosis and cirrhosis involve excess production of extracellular matrix, which is closely related to liver sinusoidal endothelial cells (LSECs). Damaged LSECs can synthesize transforming growth factor-beta and platelet-derived growth factor, which activate hepatic stellate cells and facilitate the synthesis of extracellular matrix. Herein, we highlight the angiogenic cytokines of LSECs related to liver fibrosis and cirrhosis at different stages and focus on the formation and development of liver fibrosis and cirrhosis. Inhibition of LSEC angiogenesis and antiangiogenic therapy are described in detail. Targeting LSECs has high therapeutic potential for liver diseases. Further understanding of the mechanism of action will provide stronger evidence for the development of anti-LSEC drugs and new directions for diagnosis and treatment of liver diseases.

Performance of autotaxin as a serum marker for liver fibrosis

Background Because autotaxin reportedly has a better performance than hyaluronic acid as a marker for liver fibrosis for the prediction of cirrhosis caused by hepatitis C, we aimed to further evaluate the role of autotaxin in liver fibrosis of other aetiologies. Methods Autotaxin antigen was measured in serum samples from 108 patients with chronic hepatitis B and 128 patients with non-alcoholic fatty liver disease who had undergone a liver biopsy as well as healthy subjects and patients with chronic kidney disease, diabetes mellitus, rheumatoid arthritis and cardiac dysfunction. Results When evaluated using receiver operator characteristics curves, the performance of autotaxin for the prediction of significant fibrosis (F2-F4) in chronic hepatitis B patients was better than that of hyaluronic acid or type IV collagen 7S. In non-alcoholic fatty liver disease patients, however, the performance of autotaxin for the prediction of significant fibrosis was poorer than that of hyaluronic acid or type IV collagen 7S. The increase in the serum autotaxin concentrations was less notable than that of hyaluronic acid or type IV collagen in patients with chronic kidney disease, diabetes mellitus, rheumatoid arthritis or cardiac dysfunction. Food intake did not affect the serum autotaxin concentrations. Conclusions Autotaxin is useful as a serum marker for liver fibrosis caused by not only chronic viral hepatitis C but also by hepatitis B, although it was less useful in patients with non-alcoholic fatty liver disease. The increase in serum autotaxin concentrations is fairly specific for liver fibrosis, and the serum autotaxin concentrations can be analysed without consideration of food intake before blood collection.