Autotaxin inhibition reduces cardiac inflammation and mitigates adverse cardiac remodeling after myocardial infarction

Autotaxin Inhibition Reduces Post-Ischemic Myocardial Inflammation via Epigenetic Gene Modifications

Myocardial infarction (MI) triggers a complex inflammatory response that is essential for cardiac repair but can also lead to adverse outcomes if left uncontrolled. Recent studies have highlighted the importance of epigenetic modifications in regulating post-MI inflammation. This study investigated the role of the autotaxin (ATX)/lysophosphatidic acid (LPA) signaling axis in modulating myocardial inflammation through epigenetic pathways in a mouse model of MI. C57BL/6 J mice underwent left anterior descending coronary artery ligation to induce MI and were treated with the ATX inhibitor, PF-8380, or vehicle. Cardiac tissue from the border zone was collected at 6 h, 1, 3, and 7 days post-MI for epigenetic gene profiling using RT2 Profiler PCR Arrays. The results revealed distinct gene expression patterns across sham, MI + Vehicle, and MI + PF-8380 groups. PF-8380 treatment significantly altered the expression of genes involved in inflammation, stress response, and epigenetic regulation compared to the vehicle group. Notably, PF-8380 downregulated Hdac5, Prmt5, and Prmt6, which are linked to exacerbated inflammatory responses, as early as 6 h post-MI. Furthermore, PF-8380 attenuated the reduction of Smyd1, a gene important in myogenic differentiation, at 7 days post-MI. This study demonstrates that the ATX/LPA signaling axis plays a pivotal role in modulating post-MI inflammation via epigenetic pathways. Targeting ATX/LPA signaling may represent a novel therapeutic strategy to control inflammation and improve outcomes after MI. Further research is needed to validate these findings in preclinical and clinical settings and to elucidate the complex interplay between epigenetic mechanisms and ATX/LPA signaling in the context of MI.

Lysophosphatidic acid contributes to myocardial ischemia/reperfusion injury by activating TRPV1 in spinal cord

Lysophosphatidic acid (LPA) is a bioactive phospholipid that plays a crucial role in cardiovascular diseases. Here, we question whether LPA contributes to myocardial ischemia/reperfusion (I/R) injury by acting on transient receptor potential vanilloid 1 (TRPV1) in spinal cord. By ligating the left coronary artery to establish an in vivo I/R mouse model, we observed a 1.57-fold increase in LPA level in the cerebrospinal fluid (CSF). The I/R-elevated CSF LPA levels were reduced by HA130, an LPA synthesis inhibitor, compared to vehicle treatment (4.74 ± 0.34 vs. 6.46 ± 0.94 μg/mL, p = 0.0014). Myocardial infarct size was reduced by HA130 treatment compared to the vehicle group (26 ± 8% vs. 46 ± 8%, p = 0.0001). To block the interaction of LPA with TRPV1 at the K710 site, we generated a K710N knock-in mouse model. The TRPV1K710N mice were resistant to LPA-induced myocardial injury, showing a smaller infarct size relative to TRPV1WT mice (28 ± 4% vs. 60 ± 7%, p < 0.0001). Additionally, a sequence-specific TRPV1 peptide targeting the K710 region produced similar protective effects against LPA-induced myocardial injury. Blocking the K710 region through K710N mutation or TRPV1 peptide resulted in reduced neuropeptides release and decreased activity of cardiac sensory neurons, leading to a decrease in cardiac norepinephrine concentration and the restoration of intramyocardial pro-survival signaling, namely protein kinase B/extracellular regulated kinase/glycogen synthase kinase-3β pathway. These findings suggest that the elevation of CSF LPA is strongly associated with myocardial I/R injury. Moreover, inhibiting the interaction of LPA with TRPV1 by blocking the K710 region uncovers a novel strategy for preventing myocardial ischemic injury.

Lysophosphatidic Acid-Mediated Inflammation at the Heart of Heart Failure

PURPOSE OF REVIEW

The primary aim of this review is to provide an in-depth examination of the role bioactive lipids-namely lysophosphatidic acid (LPA) and ceramides-play in inflammation-mediated cardiac remodeling during heart failure. With the global prevalence of heart failure on the rise, it is critical to understand the underlying molecular mechanisms contributing to its pathogenesis. Traditional studies have emphasized factors such as oxidative stress and neurohormonal activation, but emerging research has shed light on bioactive lipids as central mediators in heart failure pathology. By elucidating these intricacies, this review aims to: Bridge the gap between basic research and clinical practice by highlighting clinically relevant pathways contributing to the pathogenesis and prognosis of heart failure. Provide a foundation for the development of targeted therapies that could mitigate the effects of LPA and ceramides on heart failure. Serve as a comprehensive resource for clinicians and researchers interested in the molecular biology of heart failure, aiding in better diagnostic and therapeutic decisions.

RECENT FINDINGS

Recent findings have shed light on the central role of bioactive lipids, specifically lysophosphatidic acid (LPA) and ceramides, in heart failure pathology. Traditional studies have emphasized factors such as hypoxia-mediated cardiomyocyte loss and neurohormonal activation in the development of heart failure. Emerging research has elucidated the intricacies of bioactive lipid-mediated inflammation in cardiac remodeling and the development of heart failure. Studies have shown that LPA and ceramides contribute to the pathogenesis of heart failure by promoting inflammation, fibrosis, and apoptosis in cardiac cells. Additionally, recent studies have identified potential targeted therapies that could mitigate the effects of bioactive lipids on heart failure, including LPA receptor antagonists and ceramide synthase inhibitors. These recent findings provide a promising avenue for the development of targeted therapies that could improve the diagnosis and treatment of heart failure. In this review, we highlight the pivotal role of inflammation induced by bioactive lipid signaling and its influence on the pathogenesis of heart failure. By critically assessing the existing literature, we provide a comprehensive resource for clinicians and researchers interested in the molecular mechanisms of heart failure. Our review aims to bridge the gap between basic research and clinical practice by providing actionable insights and a foundation for the development of targeted therapies that could mitigate the effects of bioactive lipids on heart failure. We hope that this review will aid in better diagnostic and therapeutic decisions, further advancing our collective understanding and management of heart failure.

Macrophage-driven cardiac inflammation and healing: insights from homeostasis and myocardial infarction

Early and prompt reperfusion therapy has markedly improved the survival rates among patients enduring myocardial infarction (MI). Nonetheless, the resulting adverse remodeling and the subsequent onset of heart failure remain formidable clinical management challenges and represent a primary cause of disability in MI patients worldwide. Macrophages play a crucial role in immune system regulation and wield a profound influence over the inflammatory repair process following MI, thereby dictating the degree of myocardial injury and the subsequent pathological remodeling. Despite numerous previous biological studies that established the classical polarization model for macrophages, classifying them as either M1 pro-inflammatory or M2 pro-reparative macrophages, this simplistic categorization falls short of meeting the precision medicine standards, hindering the translational advancement of clinical research. Recently, advances in single-cell sequencing technology have facilitated a more profound exploration of macrophage heterogeneity and plasticity, opening avenues for the development of targeted interventions to address macrophage-related factors in the aftermath of MI. In this review, we provide a summary of macrophage origins, tissue distribution, classification, and surface markers. Furthermore, we delve into the multifaceted roles of macrophages in maintaining cardiac homeostasis and regulating inflammation during the post-MI period.

The multiple roles of lysophosphatidic acid in vascular disease and atherosclerosis

PURPOSE OF REVIEW

To explore the multiple roles that lysophosphatidic acid (LPA) plays in vascular disease and atherosclerosis.

RECENT FINDINGS

A high-fat high-cholesterol diet decreases antimicrobial activity in the small intestine, which leads to increased levels of bacterial lipopolysaccharide in the mucus of the small intestine and in plasma that increase systemic inflammation, and enhance dyslipidemia and aortic atherosclerosis. Decreasing LPA production in enterocytes reduces the impact of the diet. LPA signaling inhibits glucagon-like peptide 1 secretion, promotes atherosclerosis, increases vessel permeability and infarct volume in stroke, but protects against abdominal aortic aneurysm formation and rupture. Acting through the calpain system in lymphatic endothelial cells, LPA reduces the trafficking of anti-inflammatory Treg lymphocytes, which enhances atherosclerosis. Acting through LPA receptor 1 in cardiac lymphatic endothelial cells and fibroblasts, LPA enhances hypertrophic cardiomyopathy.

SUMMARY

LPA plays multiple roles in vascular disease and atherosclerosis that is cell and context dependent. In some settings LPA promotes these disease processes and in others it inhibits the disease process. Because LPA is so ubiquitous, therapeutic approaches targeting LPA must be as specific as possible for the cells and the context in which the disease process occurs.

Prognostic Significance of Activated Monocytes in Patients with ST-Elevation Myocardial Infarction

Circulating monocytes have different subsets, including classical (CD14++CD16-), intermediate (CD14++CD16+), and nonclassical (CD14+CD16++), which play different roles in cardiovascular physiology and disease progression. The predictive value of each subset for adverse clinical outcomes in patients with coronary artery disease is not fully understood. We sought to evaluate the prognostic efficacy of each monocyte subset in patients with ST-elevation myocardial infarction (STEMI). We recruited 100 patients with STEMI who underwent primary percutaneous coronary intervention (PCI). Blood samples were collected at the time of presentation to the hospital (within 6 h from onset of symptoms, baseline (BL)) and then at 3, 6, 12, and 24 h after presentation. Monocytes were defined as CD45+/HLA-DR+ and then subdivided based on the expression of CD14, CD16, CCR2, CD11b, and CD42. The primary endpoint was a composite of all-cause death, hospitalization for heart failure, stent thrombosis, in-stent restenosis, and recurrent myocardial infarction. Univariate and multivariate Cox proportional hazards models, including baseline comorbidities, were performed. The mean age of our cohort was 58.9 years and 25% of our patients were females. Patients with high levels (above the median) of CD14+CD16++ monocytes showed an increased risk for the primary endpoint in comparison to patients with low levels; adjusted hazard ratio (aHR) for CD14+/CD16++ cells was 4.3 (95% confidence interval (95% CI) 1.2-14.8, p = 0.02), for CD14+/CD16++/CCR2+ cells was 3.82 (95% CI 1.06-13.7, p = 0.04), for CD14+/CD16++/CD42b+ cells was 3.37 (95% CI 1.07-10.6, p = 0.03), for CD14+/CD16++/CD11b+ was 5.17 (95% CI 1.4-18.0, p = 0.009), and for CD14+ HLA-DR+ was 7.5 (95% CI 2.0-28.5, p = 0.002). CD14++CD16-, CD14++CD16+, and their CD11b+, CCR2+, and CD42b+ aggregates were not significantly predictive for our composite endpoint. Our study shows that CD14+ CD16++ monocytes and their subsets expressing CCR2, CD42, and CD11b could be important predictors of clinical outcomes in patients with STEMI. Further studies with a larger sample size and different coronary artery disease phenotypes are needed to verify the findings.

Phospholipids, the Masters in the Shadows during Healing after Acute Myocardial Infarction

Phospholipids are major components of cell membranes with complex structures, high heterogeneity and critical biological functions and have been used since ancient times to treat cardiovascular disease. Their importance and role were shadowed by the difficulty or incomplete available research methodology to study their biological presence and functionality. This review focuses on the current knowledge about the roles of phospholipids in the pathophysiology and therapy of cardiovascular diseases, which have been increasingly recognized. Used in singular formulation or in inclusive combinations with current drugs, phospholipids proved their positive and valuable effects not only in the protection of myocardial tissue, inflammation and fibrosis but also in angiogenesis, coagulation or cardiac regeneration more frequently in animal models as well as in human pathology. Thus, while mainly neglected by the scientific community, phospholipids present negligible side effects and could represent an ideal target for future therapeutic strategies in healing myocardial infarction. Acknowledging and understanding their mechanisms of action could offer a new perspective into novel therapeutic strategies for patients suffering an acute myocardial infarction, reducing the burden and improving the general social and economic outcome.

Role of Enterocyte Enpp2 and Autotaxin in Regulating Lipopolysaccharide Levels, Systemic Inflammation and Atherosclerosis

Conversion of lysophosphatidylcholine (LPC) to lysophosphatidic acid (LPA) by autotaxin, a secreted phospholipase D, is a major pathway for producing LPA. We previously reported that feeding Ldlr^-/- mice standard mouse chow supplemented with unsaturated LPA or LPC qualitatively mimicked the dyslipidemia and atherosclerosis induced by feeding a Western diet (WD). Here we report that adding unsaturated LPA to standard mouse chow also increased the content of reactive oxygen species (ROS) and oxidized phospholipids (OxPL) in jejunum mucus. To determine the role of intestinal autotaxin, enterocyte specific Ldlr^-/-/Enpp2 knockout (iKO) mice were generated. In control mice, the WD increased enterocyte Enpp2 expression and raised autotaxin levels. Ex vivo, addition of OxPL to jejunum from Ldlr^-/- mice on a chow diet induced expression of Enpp2. In control mice, the WD raised OxPL levels in jejunum mucus, and decreased gene expression in enterocytes for a number of peptides and proteins that affect antimicrobial activity. On the WD, the control mice developed elevated levels of LPS in jejunum mucus and plasma, with increased dyslipidemia and increased atherosclerosis. All of these changes were reduced in the iKO mice. We conclude that the WD increases the formation of intestinal OxPL, which i) induce enterocyte Enpp2 and autotaxin resulting in higher enterocyte LPA levels; that ii) contribute to the formation of ROS that help to maintain the high OxPL levels; iii) decrease intestinal antimicrobial activity; and iv) raise plasma LPS levels that promote systemic inflammation and enhance atherosclerosis.

Endothelial Specific Deletion of Autotaxin Improves Stroke Outcomes

Autotaxin (ATX) is an extracellular secretory enzyme (lysophospholipase D) that catalyzes the hydrolysis of lysophosphatidyl choline to lysophosphatidic acid (LPA). The ATX-LPA axis is a well-known pathological mediator of liver fibrosis, metastasis in cancer, pulmonary fibrosis, atherosclerosis, and neurodegenerative diseases. Additionally, it is believed that LPA may cause vascular permeability. In ischemic stroke, vascular permeability leading to hemorrhagic transformation is a major limitation for therapies and an obstacle to stroke management. Therefore, in this study, we generated an endothelial-specific ATX deletion in mice (ERT2 ATX-/-) to observe stroke outcomes in a mouse stroke model to analyze the role of endothelial ATX. The AR2 probe and Evans Blue staining were used to perform the ATX activity and vascular permeability assays, respectively. Laser speckle imaging was used to observe the cerebral blood flow following stroke. In this study, we observed that stroke outcomes were alleviated with the endothelial deletion of ATX. Permeability and infarct volume were reduced in ERT2 ATX-/- mice compared to ischemia-reperfusion (I/R)-only mice. In addition, the cerebral blood flow was retained in ERT2 ATX-/- compared to I/R mice. The outcomes in the stroke model are alleviated due to the limited LPA concentration, reduced ATX concentration, and ATX activity in ERT2 ATX-/- mice. This study suggests that endothelial-specific ATX leads to increased LPA in the brain vasculature following ischemic-reperfusion and ultimately disrupts vascular permeability, resulting in adverse stroke outcomes.

Combined Transplantation of Human MSCs and ECFCs Improves Cardiac Function and Decrease Cardiomyocyte Apoptosis After Acute Myocardial Infarction

BACKGROUND

Ischemic heart disease, often caused by an acute myocardial infarction (AMI) is one of the leading causes of morbidity and mortality worldwide. Despite significant advances in medical and procedural therapies, millions of AMI patients progress to develop heart failure every year.

METHODS

Here, we examine the combination therapy of human mesenchymal stromal cells (MSCs) and endothelial colony-forming cells (ECFCs) to reduce the early ischemic damage (MSCs) and enhance angiogenesis (ECFCs) in a pre-clinical model of acute myocardial infarction. NOD/SCID mice were subjected to AMI followed by transplantation of MSCs and ECFCs either alone or in combination. Cardiomyocyte apoptosis and cardiac functional recovery were assessed in short- and long-term follow-up studies.

RESULTS

At 1 day after AMI, MSC- and ECFC-treated animals demonstrated significantly lower cardiomyocyte apoptosis compared to vehicle-treated animals. This phenomenon was associated with a significant reduction in infarct size, cardiac fibrosis, and improvement in functional cardiac recovery 4 weeks after AMI.

CONCLUSIONS

The use of ECFCs, MSCs, and the combination of both cell types reduce cardiomyocyte apoptosis, scar size, and adverse cardiac remodeling, compared to vehicle, in a pre-clinical model of AMI. These results support the use of this combined cell therapy approach in future human studies during the acute phase of ischemic cardiac injury.

Role of autotaxin in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a prototypic systemic autoimmune disease characterized by the production of various autoantibodies and deposition of immune complexes. SLE is a heterogenous disease, and the pattern of organ involvement and response to treatment differs significantly among patients. Novel biological markers are necessary to assess the extent of organ involvement and predict treatment response in SLE. Lysophosphatidic acid is a lysophospholipid involved in various biological processes, and autotaxin (ATX), which catalyzes the production of lysophosphatidic acid in the extracellular space, has gained attention in various diseases as a potential biomarker. The concentration of ATX is increased in the serum and urine of patients with SLE and lupus nephritis. Recent evidence suggests that ATX produced by plasmacytoid dendritic cells may play an important role in the immune system and pathogenesis of SLE. Furthermore, the production of ATX is associated with type I interferons, a key cytokine in SLE pathogenesis, and ATX may be a potential biomarker and key molecule in SLE.

Fibrotic Response of Human Trabecular Meshwork Cells to Transforming Growth Factor-Beta 3 and Autotaxin in Aqueous Humor

This study examines the potential role of transforming growth factor-beta 3 (TGF-β3) on the fibrotic response of cultured human trabecular meshwork (HTM) cells. The relationships and trans-signaling interactions between TGF-β3 and autotaxin (ATX) in HTM cells were also examined. The levels of TGF-β and ATX in the aqueous humor (AH) of patients were measured by an immunoenzymetric assay. The TGF-β3-induced expression of the fibrogenic markers, fibronectin, collagen type I alpha 1 chain, and alpha-smooth muscle actin, and ATX were examined by quantitative real-time PCR, Western blotting, and immunocytochemistry, and the trans-signaling regulatory effect of TGF-β3 on ATX expression was also evaluated. In HTM cells, the significant upregulation of ATX was induced by TGF-β3 at a concentration of 0.1 ng/mL, corresponding to the physiological concentration in the AH of patients with exfoliative glaucoma (XFG). However, higher concentrations of TGF-β3 significantly suppressed ATX expression. TGF-β3 regulated ATX transcription and signaling in HTM cells, inducing the upregulation of fibrogenic proteins in a dose-dependent manner. Trans-signaling of TGF-β3 regulated ATX transcription, protein expression, and signaling, and was thereby suggested to induce fibrosis of the trabecular meshwork. Modulation of trans-signaling between TGF-β3 and ATX may be key to elucidate the pathology of XFG, and for the development of novel treatment modalities.

Dexamethasone Alleviates Myocardial Injury in a Rat Model of Acute Myocardial Infarction Supported by Venoarterial Extracorporeal Membrane Oxygenation

Myocardial ischemia causes myocardial inflammation. Research indicates that the venoarterial extracorporeal membrane oxygenation (VA ECMO) provides cardiac support; however, the inflammatory response caused by myocardial ischemia remains unresolved. Dexamethasone (Dex), a broad anti-inflammatory agent, exhibits a cardioprotective effect. This study aims to investigate the effect of Dex on a rat model of acute myocardial infarction (AMI) supported by VA ECMO. Male Sprague-Dawley rats (300–350 g) were randomly divided into three groups: Sham group (n = 5), ECMO group (n = 6), and ECMO + Dex group (n = 6). AMI was induced by ligating the left anterior descending (LAD) coronary artery. Sham group only thoracotomy was performed but LAD was not ligated. The ECMO and ECMO + Dex groups were subjected to 1 h of AMI and 2 h of VA ECMO. In the ECMO + Dex group, Dex (0.2 mg/kg) was intravenously injected into the rats after 1 h of AMI. Lastly, myocardial tissue and blood samples were harvested for further evaluation. The ECMO + Dex group significantly reduced infarct size and levels of cTnI, cTnT, and CK-MB. Apoptotic cells and the expression levels of Bax, Caspase3, and Cle-Caspase3 proteins were markedly lower in the ECMO + Dex group than that in the ECMO group. Neutrophil and macrophage infiltration was lower in the ECMO + Dex group than in the ECMO group. A significant reduction was noted in ICAM-1, C5a, MMP-9, IL-1β, IL-6, and TNF-α. In summary, our findings revealed that Dex alleviates myocardial injury in a rat model of AMI supported by VA ECMO.

Therapeutic and Prognostic Significance of Arachidonic Acid in Heart Failure

BACKGROUND

Accurate prediction of death is an unmet need in patients with acute decompensated heart failure (HF). Arachidonic acid (AA) metabolites play an important role in the multiple pathophysiological processes. We aimed to develop an AA score to accurately predict mortality in patients with acute decompensated HF and explore the causal relationship between the AA predictors and HF.

METHODS

The serum AA metabolites was measured in patients with acute decompensated HF (discovery cohort n=419; validation cohort n=386) by mass spectroscopy. We assessed the prognostic importance of AA metabolites for 1-year death using Cox regression and machine learning approaches. An machine learning-based AA score for predicting 1-year death was created and validated. We explored the mechanisms using transcriptome and functional experiments in a mouse model of early ischemic cardiomyopathy.

RESULTS

Among the 27 AA metabolites, elevated 14,15-DHET/14,15-EET ratio was the strongest predictor of 1-year death (hazard ratio, 2.10, P=3.1×10^-6). Machine learning-based AA score using a combination of the 14,15-DHET/14,15-EET ratio, 14,15-DHET, PGD2, and 9-HETE performed best (area under the curve [AUC]: 0.85). The machine learning-based AA score provided incremental information to predict mortality beyond BNP (B-type natriuretic peptide; ΔAUC: 0.19), clinical score (ΔAUC: 0.09), and preexisting ADHERE, Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients With Heart Failure, and Get With The Guidelines Heart Failure scores (ΔAUC: 0.17, 0.17, 0.15, respectively). In the validation cohort, the AA score accurately predicted mortality (AUC:0.81). False-negative and false-positive findings, as classified by the BNP threshold, were correctly reclassified by the AA score (46.2% of false-negative and 84.5% of false-positive). In a murine model, the expression and enzymatic activity of sEH (soluble epoxide hydrolase) increased after myocardial infarction. Genetic deletion of sEH improved HF and the blockade of 14,15-EET abolished this cardioprotection. We mechanistically revealed the beneficial effect of 14,15-EET by impairing the activation of monocytes/macrophages.

CONCLUSIONS

Our studies propose that the AA score predicts death in patients with acute decompensated HF and inhibiting sEH serves as a therapeutic target for treating HF.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04108182.

Serum autotaxin as a novel prognostic marker in patients with non-ischaemic dilated cardiomyopathy

Aims

Autotaxin (ATX) promotes myocardial inflammation, fibrosis, and the subsequent cardiac remodelling through lysophosphatidic acid production. However, the prognostic impact of serum ATX in non‐ischaemic dilated cardiomyopathy (NIDCM) has not been clarified. We investigated the prognostic impact of serum ATX in patients with NIDCM.

Methods and results

We enrolled 104 patients with NIDCM (49.8 ± 13.4 years, 76 men). We divided the patients into two groups using different cutoffs of median serum ATX levels for men and women: high‐ATX group and low‐ATX group. Cardiac events were defined as a composite of cardiac death and heart failure resulting in hospitalization. Median ATX level was 203.5 ng/mL for men and 257.0 ng/mL for women. Brain natriuretic peptide levels [224.0 (59.6–689.5) pg/mL vs. 96.5 (40.8–191.5) pg/mL, P = 0.010] were higher in the high‐ATX group than low‐ATX group, whereas high‐sensitivity C‐reactive protein and collagen volume fraction levels in endomyocardial biopsy samples were not significantly different between the two groups. Kaplan–Meier survival analysis revealed that the event‐free survival rate was significantly lower in the high‐ATX group than low‐ATX group (log‐rank; P = 0.007). Cox proportional hazard analysis revealed that high‐ATX was an independent determinant of composite cardiac events. In both sexes, serum ATX levels did not correlate with high‐sensitivity C‐reactive protein levels and collagen volume fraction but had a weak correlation with brain natriuretic peptide levels (men; spearman's rank: 0.274, P = 0.017, women; spearman's rank: 0.378, P = 0.048).

Conclusion

High serum ATX levels can be associated with increasing adverse clinical outcomes in patients with NIDCM. These results indicate serum ATX may be a novel biomarker or therapeutic target in NIDCM.

Aberrant ENPP2 expression promotes tumor progression in multiple myeloma

Ectonucleotide pyrophosphatase/phosphodiesterase 2 (ENPP2) has been recently linked to tumor development. However, its role in modulating multiple myeloma (MM) disease progression remains unclear. Here, we demonstrated that CD138+ cells isolated from MM patients presented with higher expression of ENPP2 compared with CD138- cells. Treatment of MM cells with IL-6 resulted in ENPP2 upregulation. ENPP2 overexpression promoted proliferation, inhibited apoptosis, increased lysophosphatidic acid (LPA) generation, and upregulated osteoclastogenesis mediator expression in MM cells. In contrast, ENPP2 inhibition induced apoptosis, suppressed proliferation and survival, decreased LPA generation and downregulated osteoclastogenesis mediator expression. In an MM xenograft mouse model, ENPP2 knockdown significantly reduced MM tumor burden by inhibiting cell proliferation and inducing apoptosis. Furthermore, ENPP2 knockdown decreased the levels of LPA, osteoclastogenesis mediators in sera of mice with MM. Our findings revealed the tumor-promoting role of ENPP2 in MM, thus providing new molecular evidence for targeting the ENPP2-LPA axis in MM therapy.

The linkage between inflammation and fibrosis in muscular dystrophies: The axis autotaxin-lysophosphatidic acid as a new therapeutic target?

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