Gliovascular interface abnormality in mice with endothelial cell senescence.

In the brain, neurons, glial cells, vascular endothelial cells (ECs), and mural cells form a functional structure referred to as the neurovascular unit (NVU). The functions of the NVU become impaired with aging. To gain insight into the mechanism underlying the aging-related changes in the NVU, we characterized in the present study the gliovascular interface in transgenic mice expressing a dominant-negative form of the telomeric repeat-binding factor 2 (TERF2) specifically in ECs using the Tie2 promoter. In these transgenic mice, senescence occurred in the cerebral ECs and was accompanied by upregulation of the mRNAs of proinflammatory cell adhesion molecules and cytokines. It is noteworthy that in the deep layers of the cerebral cortex, astrocytes exhibited an increase in the signals for S100ß as well as a decrease in the polarization of the water channel aquaporin-4 (AQP4) to the perivascular endfeet of the astrocytes. Mechanistically, the perivascular localization of dystroglycan and its ligand, laminin α2, was decreased, and their localization correlated well with the perivascular localization of AQP4, which supports the notion that their interaction regulates the perivascular localization of AQP4. The diminished perivascular localization of laminin α2 may be attributed to its proteolytic degradation by the matrix metalloproteinase-2 released by senescent ECs. Pericyte coverage was increased and negatively correlated with the decrease in the perivascular localization of AQP4. We propose that aging-related changes in ECs induce a mild morphological alteration of astrocytes and affect the localization of AQP4 at the gliovascular interface.

An electrocardiographic score to predict pulmonary hypertension in children with atrial septal defect.

BACKGROUND: In limited resource settings, identification of factors that predict the occurrence of pulmonary hypertension(PH) in children with atrial septal defect(ASD) is important to decide which patients should be prioritized for defect closure to prevent complication. Echocardiography and cardiac catheterization are not widely available in such settings. No scoring system has been proposed to predict PH among children with ASD. We aimed to develop a PH prediction score using electrocardiography parameters for children with ASD in Indonesia. METHODS: A cross-sectional study reviewing medical record including ECG record was conducted among all children with newly diagnosed isolated ASD admitted to Dr Sardjito Hospital in Yogyakarta, Indonesia during 2016-2018. Diagnosis of ASD and PH was confirmed through echocardiography and/or cardiac catheterization. Spiegelhalter Knill-Jones approach was used to develop PH prediction score. Accuracy of prediction score was performed using a receiver operating characteristic (ROC) curve. RESULTS: Of 144 children, 50(34.7%) had PH. Predictors of pulmonary hypertension were QRS axis ≥120°, P wave ≥ 3 mm at lead II, R without S at V1, Q wave at V1, right bundle branch block (RBBB), R wave at V1, V2 or aVR > normal limit and S wave at V6 or lead I > normal limit. ROC curve from prediction scores yielded an area under the curve (AUC) 0.908(95% CI 0.85-0.96). Using the cut-off value 3.5, this PH prediction score had sensitivity of 76%(61.8-86.9), specificity 96.8%(91.0-99.3), positive predictive value 92.7%(80.5-97.5), negative predictive value 88.4%(82.2-92.6), and positive likelihood ratio 23.8(7.7-73.3). CONCLUSIONS: A presence of PH in children with ASD can be predicted by the simple electrocardiographic score including QRS axis ≥120°, P wave ≥3 mm at lead II, R without S at V1, Q wave at V1, RBBB, R wave at V1, V2 or aVR > normal limit and S wave at V6 or lead I > normal limit. A total score ≥ 3.5 shows a moderate sensitivity and high specificity to predict PH among children with ASD.

Inactivating the Uninhibited: The Tale of Activins and Inhibins in Pulmonary Arterial Hypertension.

Advances in technology and biomedical knowledge have led to the effective diagnosis and treatment of an increasing number of rare diseases. Pulmonary arterial hypertension (PAH) is a rare disorder of the pulmonary vasculature that is associated with high mortality and morbidity rates. Although significant progress has been made in understanding PAH and its diagnosis and treatment, numerous unanswered questions remain regarding pulmonary vascular remodeling, a major factor contributing to the increase in pulmonary arterial pressure. Here, we discuss the role of activins and inhibins, both of which belong to the TGF-ß superfamily, in PAH development. We examine how these relate to signaling pathways implicated in PAH pathogenesis. Furthermore, we discuss how activin/inhibin-targeting drugs, particularly sotatercep, affect pathophysiology, as these target the afore-mentioned specific pathway. We highlight activin/inhibin signaling as a critical mediator of PAH development that is to be targeted for therapeutic gain, potentially improving patient outcomes in the future.

GPNMB plays a protective role against obesity-related metabolic disorders by reducing macrophage inflammatory capacity.

Obesity is a global health problem that is often related to cardiovascular and metabolic diseases. Chronic low-grade inflammation in white adipose tissue (WAT) is a hallmark of obesity. Previously, during a search for differentially expressed genes in WAT of obese mice, we identified glycoprotein nonmetastatic melanoma protein B (GPNMB), of which expression was robustly induced in pathologically expanded WAT. Here, we investigated the role of GPNMB in obesity-related metabolic disorders utilizing GPNMB-deficient mice. When fed a high-fat diet (HFD), GPNMB-deficient mice showed body weight and adiposity similar to those of wild-type (WT) mice. Nonetheless, insulin and glucose tolerance tests revealed significant obesity-related metabolic disorders in GPNMB-KO mice compared with WT mice fed with HFD. Chronic WAT inflammation was remarkably worsened in HFD-fed GPNMB-KO mice, accompanied by a striking increase in crown-like structures, typical hallmarks for diseased WAT. Macrophages isolated from GPNMB-KO mice were observed to produce more inflammatory cytokines than those of WT mice, a difference abolished by supplementation with recombinant soluble GPNMB extracellular domain. We demonstrated that GPNMB reduced the inflammatory capacity of macrophages by inhibiting NF-κB signaling largely through binding to CD44. Finally, we showed that macrophage depletion by addition of clodronate liposomes abolished the worsened WAT inflammation and abrogated the exacerbation of metabolic disorders in GPNMB-deficient mice fed on HFD. Our data reveal that GPNMB negatively regulates macrophage inflammatory capacities and ameliorates the WAT inflammation in obesity; therefore we conclude that GPNMB is a promising therapeutic target for the treatment of metabolic disorders associated with obesity.

Budesonide/glycopyrronium/formoterol fumarate triple therapy prevents pulmonary hypertension in a COPD mouse model via NFκB inactivation.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a health problem that results in death, commonly due to the development of pulmonary hypertension (PH). Here, by utilizing a mouse model of intratracheal elastase-induced emphysema that presents three different phases of COPD, we sought to observe whether budesonide/glycopyrronium/formoterol fumarate (BGF) triple therapy could prevent COPD-PH in addition to ameliorating COPD progression. METHODS: We utilized intratracheal elastase-induced emphysema mouse model and performed experiments in three phases illustrating COPD progression: inflammatory (1 day post-elastase), emphysema (3 weeks post-elastase) and PH (4 weeks post-elastase), while treatments of BGF and controls (vehicle, one-drug, and two-drug combinations) were started in prior to elastase instillation (inflammatory phase), at day 7 (emphysema), or at day 14 (PH phase). Phenotype analyses were performed in each phase. In vitro, A549 cells or isolated mouse lung endothelial cells (MLEC) were treated with TNFα with/without BGF treatment to analyze NFκB signaling and cytokine expression changes. RESULTS: We observed significant reductions in the proinflammatory phenotype observed in the lungs and bronchoalveolar lavage fluid (BALF) 1 day after elastase administration in mice treated with BGF compared with that in mice administered elastase alone (BALF neutrophil percentage, p = 0.0011 for PBS/Vehicle vs. PBS/Elastase, p = 0.0161 for PBS/Elastase vs. BGF). In contrast, only BGF treatment significantly ameliorated the elastase-induced emphysematous lung structure and desaturation after three weeks of elastase instillation (mean linear intercept, p = 0.0156 for PBS/Vehicle vs. PBS/Elastase, p = 0.0274 for PBS/Elastase vs. BGF). Furthermore, BGF treatment prevented COPD-PH development, as shown by improvements in the hemodynamic and histological phenotypes four weeks after elastase treatment (right ventricular systolic pressure, p = 0.0062 for PBS/Vehicle vs. PBS/Elastase, p = 0.027 for PBS/Elastase vs. BGF). Molecularly, BGF acts by inhibiting NFκB-p65 phosphorylation and subsequently decreasing the mRNA expression of proinflammatory cytokines in both alveolar epithelial and pulmonary endothelial cells. CONCLUSION: Our results collectively showed that BGF treatment could prevent PH in addition to ameliorating COPD progression via the inhibition of inflammatory NFκB signaling.

Chondroitin Sulfate N-acetylgalactosaminyltransferase-2 Impacts Foam Cell Formation and Atherosclerosis by Altering Macrophage Glycosaminoglycan Chain.

OBJECTIVE: Chondroitin sulfate proteoglycans are the primary constituents of the macrophage glycosaminoglycan and extracellular microenvironment. To examine their potential role in atherogenesis, we investigated the biological importance of one of the chondroitin sulfate glycosaminoglycan biosynthesis gene, ChGn-2 (chondroitin sulfate N-acetylgalactosaminyltransferase-2), in macrophage foam cell formation. Approach and Results: ChGn-2-deficient mice showed decreased and shortened glycosaminoglycans. ChGn-2-/-/LDLr-/- (low-density lipoprotein receptor) mice generated less atherosclerotic plaque after being fed with Western diet despite exhibiting a metabolic phenotype similar to that of the ChGn-2+/+/LDLr-/- littermates. We demonstrated that in macrophages, ChGn-2 expression was upregulated in the presence of oxLDL (oxidized LDL), and glycosaminoglycan was substantially increased. Foam cell formation was significantly altered by ChGn-2 in both mouse peritoneal macrophages and the RAW264.7 macrophage cell line. Mechanistically, ChGn-2 enhanced oxLDL binding on the cell surface, and as a consequence, CD36-an important macrophage membrane scavenger receptor-was differentially regulated. CONCLUSIONS: ChGn-2 alteration on macrophages conceivably influences LDL accumulation and subsequently accelerates plaque formation. These results collectively suggest that ChGn-2 is a novel therapeutic target amenable to clinical translation in the future. Graphic Abstract: A graphic abstract is available for this article.

The loss of endothelin-2 exhibits an anticancer effect in A549 human lung adenocarcinoma cell line.

Lung cancer is the leading cause of cancer-related deaths worldwide, and adenocarcinoma is the most common subtype of lung cancer. Endothelin-2 (ET-2) is expressed in the epithelium of alveoli, and its expression is increased in cancer. However, the role of ET-2 in lung adenocarcinoma remains unclear. This study aimed to investigate the pathophysiological functions of ET-2 in A549 human lung adenocarcinoma cells. We analyzed the expression of ET-2 mRNA in lung adenocarcinoma tissues compared with that in nontumor lung tissues using public online databases. The function of ET-2 in A549 cells was investigated using siRNA. ET-2 mRNA level was upregulated in lung adenocarcinoma tissues, and high ET-2 level was associated with poor overall survival in patients with lung adenocarcinoma. ET-2 silencing reduced the proliferation, migration, and invasion, and enhanced apoptosis in A549 cells. Mechanistically, ET-2 silencing reduced the expression levels of X-linked inhibitor of apoptosis and survivin, which are members of the inhibitor apoptosis protein family. In addition, silencing ET-2 inhibited epithelial-mesenchymal transition, which halted migration. Therefore, the specific targeting of ET-2 may be a potential treatment strategy for lung adenocarcinoma.

Usefulness of Combining NT-proBNP Level and Right Atrial Diameter for Simple and Early Noninvasive Detection of Pulmonary Hypertension Among Adult Patients with Atrial Septal Defect.

BACKGROUND: Atrial septal defect developed pulmonary hypertension (ASD-PH) at first diagnosis due to late presentation are common in Indonesia. Transthoracic echocardiogram (TTE) is a common tool to detect ASD-PH, before proceeding to invasive procedure. The NT-proBNP measurement to screen ASD-PH is not yet considered the standard approach, especially in limited resource conditions. The objective of this study is to assess the value of NT-proBNP, along with simple TTE parameter, to screen PH among adults with ASD. METHODS: This was a cross-sectional study. The subjects were adult ASD-PH patients from the COHARD-PH  registry (n=357). Right heart catheterization (RHC) was performed to diagnose PH. Blood sample was withdrawn during RHC for NT-proBNP measurement. The TTE was performed as standard procedure and its regular parameters were assessed, along with NT-proBNP, to detect PH. RESULTS: Two parameters significantly predicted PH, namely NT-proBNP and right atrial (RA) diameter. The cut-off of NT-proBNP to detect PH was ≥140 pg/mL. The cut-off of RA diameter to detect PH was ≥46.0 mm. The combined values of NT-proBNP level ≥140 pg/mL and RA diameter ≥46.0 mm yielded 46.6% sensitivity, 91.8% specificity, 54.3% accuracy, 96.5% positive predictive value and 26.2% negative predictive value to detect PH, which were better than single value. CONCLUSION: NT-proBNP level ≥140 pg/mL represented PH in adult ASD patients. The NT-proBNP level ≥140 pg/mL and RA diameter ≥46.0 mm had a pre-test probability measures to triage patients needing more invasive procedure and also to determine when and if to start the PH-specific treatment.

Multi-Institutional Prospective Cohort Study of Patients With Pulmonary Hypertension Associated With Respiratory Diseases.

BACKGROUND: There is limited evidence for pulmonary arterial hypertension (PAH)-targeted therapy in patients with pulmonary hypertension associated with respiratory disease (R-PH). Therefore, we conducted a multicenter prospective study of patients with R-PH to examine real-world characteristics of responders by evaluating demographics, treatment backgrounds, and prognosis.Methods and Results:Among the 281 patients with R-PH included in this study, there was a treatment-naïve cohort of 183 patients with normal pulmonary arterial wedge pressure and 1 of 4 major diseases (chronic obstructive pulmonary diseases, interstitial pneumonia [IP], IP with connective tissue disease, or combined pulmonary fibrosis with emphysema); 43% of patients had mild ventilatory impairment (MVI), whereas 52% had a severe form of PH. 68% received PAH-targeted therapies (mainly phosphodiesterase-5 inhibitors). Among patients with MVI, those treated initially (i.e., within 2 months of the first right heart catheterization) had better survival than patients not treated initially (3-year survival 70.6% vs. 34.2%; P=0.01); there was no significant difference in survival in the group with severe ventilatory impairment (49.6% vs. 32.1%; P=0.38). Responders to PAH-targeted therapy were more prevalent in the group with MVI. CONCLUSIONS: This first Japanese registry of R-PH showed that a high proportion of patients with MVI (PAH phenotype) had better survival if they received initial treatment with PAH-targeted therapies. Responders were predominant in the group with MVI.

Family with sequence similarity 13, member A modulates adipocyte insulin signaling and preserves systemic metabolic homeostasis.

Adipose tissue dysfunction is causally implicated in the impaired metabolic homeostasis associated with obesity; however, detailed mechanisms underlying dysregulated adipocyte functions in obesity remain to be elucidated. Here we searched for genes that provide a previously unknown mechanism in adipocyte metabolic functions and identified family with sequence similarity 13, member A (Fam13a) as a factor that modifies insulin signal cascade in adipocytes. Fam13a was highly expressed in adipose tissue, predominantly in mature adipocytes, and its expression was substantially reduced in adipose tissues of obese compared with lean mice. We revealed that Fam13a accentuated insulin signaling by recruiting protein phosphatase 2A with insulin receptor substrate 1 (IRS1), leading to protection of IRS1 from proteasomal degradation. We further demonstrated that genetic loss of Fam13a exacerbated obesity-related metabolic disorders, while targeted activation of Fam13a in adipocytes ameliorated it in association with altered adipose tissue insulin sensitivity in mice. Our data unveiled a previously unknown mechanism in the regulation of adipocyte insulin signaling by Fam13a and identified its significant role in systemic metabolic homeostasis, shedding light on Fam13a as a pharmacotherapeutic target to treat obesity-related metabolic disorders.

Predictors of Long-term Outcomes in Patients With Connective Tissue Disease Associated With Pulmonary Arterial Hypertension.

BACKGROUND/OBJECTIVE: Pulmonary arterial hypertension (PAH) is a progressive disease characterized by increased pulmonary arterial pressure and pulmonary vascular resistance that can lead to right-sided heart failure. Connective tissue disease-associated PAH (CTD-PAH) often has poorer outcomes than idiopathic or hereditary PAH, suggesting the presence of non-PAH factors that could affect the prognoses. This cohort study aimed to identify prognostic factors for CTD-PAH management. METHODS: Medical records from April 1999 to November 2014 were reviewed to determine the time from treatment initiation to the occurrence of a clinically worsening event and the time elapsed until death. Data at baseline and the final assessment were used to identify prognostic factors associated with events using univariate and multivariate analyses by the stepwise Cox regression method. RESULTS: In 36 patients with CTD-PAH analyzed, the proportions with no clinically worsening events at 1, 2, and 3 years after treatment initiation were 62%, 52%, and 45%, respectively, with survival rates of 88%, 77%, and 77%, respectively. The regression model showed that reduced hemoglobin at baseline, reduced qR pattern in electrocardiogram lead V1, increased 60-minute erythrocyte sedimentation rate, and increased mean pulmonary arterial pressure at the final assessment were risk factors that were significantly associated with clinical worsening. For survival, no prognostic factor was identifiable. CONCLUSIONS: Hemodynamic and non-PAH factors, such as anemia, nutritional status, and inflammatory activity of the underlying CTD, which are not listed in the risk assessment table of PAH guidelines, should be strictly controlled to improve the prognosis of patients with CTD-PAH. A more multifactorial treatment strategy should be developed.

Endothelin XVI.

Although 31 years have passed since the discovery of endothelin, that pioneering report, and the subsequent flood of influential studies elucidating its molecular and clinical details, have since paved the way for thousands of publications. They showed the promise of endothelin and the vast amount of work that remains to be done to fully unleash the potential this peptide possesses, both as a key physiological regulator and as a therapeutic target. Endothelin conferences and their proceedings have served as a host for many of these breakthrough studies, and in keeping with this fine tradition, Endothelin XVI will host novel research articles presented at the Sixteenth International Conference on Endothelin (ET-16) as its proceedings. On September 22-25, 2019, ET-16 was held at Kobe Port Oasis, Kobe, Japan, where numerous important discoveries were presented to the scientific community for the first time, many of which are compiled and published in this special issue. As the Editors of this special issue that comprises in-depth reviews, insightful editorials, and numerous original research articles discussing findings from various biomedical fields, we are extremely proud to present Endothelin XVI. We sincerely hope for the continued growth of this field for the benefit of the patients and the advancement of biomedical science.

The Sixteenth International Conference on Endothelin (ET-16), Kobe, 2019.

The Sixteenth International Conference on Endothelin (ET-16) was held September 22-25, 2019, in Kobe Port Oasis, Kobe, Japan, and co-chaired by Noriaki Emoto, MD, PhD, from Kobe Pharmaceutical University and Bambang Widyantoro, MD, PhD, from the University of Indonesia. As the sixteenth iteration of this biannual conference that has been held since 1988, ET-16 provided a platform for researchers of all generations from all parts of the world to present novel discoveries in the field of endothelin. ET-16 returned to Asia and to Kobe, Japan, after 6 years of alternating venues with North America and Europe, with over 100 participants attending, sharing, and discussing the newest findings on endothelin and endothelin receptor antagonists in science and medicine.

Chondroitin sulfate mediates liver responses to injury induced by dual endothelin receptor inhibition.

Although dual endothelin receptor antagonists (ERAs) show great promise for treating various conditions, their propensity to induce liver injury limits their clinical usage. Inflammation and fibrosis are important processes in liver responses to injury and it has been suggested that they and dual ERA-induced liver injury are mediated by the proteoglycan component chondroitin sulfate (CS), which is synthesized by CHST3 and CHST13. In this study, we investigated whether dual ER inhibition in the liver could alter CHST3 and CHST13 expression and thus CS production and whether liver CS content could prevent inflammatory and fibrosis responses after liver injury. We observed increased CHST3 and CHST13 expression after liver injury in bile duct ligated mice and histologically confirmed abundant CS deposition in the injured liver. Moreover, treating Hep3B cells with a dual ERA mimic significantly increased CHST3 and CHST13 expression, inflammatory cytokine levels, and glycosaminoglycan deposition. Furthermore, pro-inflammatory and pro-fibrotic markers were observed after dual ERA treatment, while treatment with CS-degrading chondroitinase ABC was able to successfully reverse these phenotypes. These observations suggest that CHST3- and CHST13-induced CS production can mediate liver injury responses caused by dual ER inhibition and thus could be an alternative pathway for treating ERA-induced liver injury.

Predictive model of bosentan-induced liver toxicity in Japanese patients with pulmonary arterial hypertension.

Bosentan, an endothelin receptor antagonist, has been widely used as a first-line medication for the treatment of pulmonary arterial hypertension (PAH). It has been shown to improve symptoms of hypertension, exercise capacity, and hemodynamics and prolong time to clinical worsening. However, liver dysfunction is a major side effect of bosentan treatment that could hamper the optimal management of patients with PAH. Previously, we demonstrated, using drug metabolism enzymes and transporters analysis, that the carbohydrate sulfotransferase 3 (CHST3) and CHST13 alleles are significantly more frequent in patients with elevated aminotransferases during therapy with bosentan than they are in patients without liver toxicity. In addition, we constructed a pharmacogenomics model to predict bosentan-induced liver injury in patients with PAH using two single-nucleotide polymorphisms and two nongenetic factors. The purpose of the present study was to externally validate the predictive model of bosentan-induced liver toxicity in Japanese patients. We evaluated five cases of patients treated with bosentan, and one presented with liver dysfunction. We applied mutation alleles of CHST3 and CHST13, serum creatinine, and age to our model to predict liver dysfunction. The sensitivity and specificity were calculated as 100% and 50%, respectively. Considering that PAH is a rare disease, multicenter collaboration would be necessary to validate our model.

Chondroitin sulfate N-acetylgalactosaminyltransferase-2 deletion alleviates lipoprotein retention in early atherosclerosis and attenuates aortic smooth muscle cell migration.

Glycosaminoglycans (GAGs) play an integral role in low-density lipoprotein (LDL) retention in the vascular intimal layer and have emerged as attractive therapeutic targets for atherosclerosis. GAG biosynthesis involves the cooperation of numerous enzymes. Chondroitin sulfate N-acetylgalactosaminyltransferase-2 (ChGn-2) is a vital Golgi transferase that participates in enzymatic elongation of GAGs. Here, we investigated the effects of ChGn-2 gene deletion on the development of atherosclerosis. Partial carotid artery ligation was performed on ChGn-2-/-/LDLr-/- and ChGn-2+/+/LDLr-/- mice to induce diffuse intimal thickening (DIT). Aortic smooth muscle cells (ASMCs) were isolated to investigate cellular LDL binding and migration. Histological analysis of human coronary artery sections revealed that ChGn-2 was expressed in early and advanced atherosclerotic lesions. Deletion of the ChGn-2 gene significantly reduced LDL retention in the DIT mouse model. Furthermore, LDL binding, visualized using rhodamine-labeled LDLs, was dramatically reduced. Interestingly, a functional assay of ASMCs prepared from ChGn-2-/- mice displayed abrogation of platelet-derived growth factor (PDGF)-mediated migration via reduced PDGF receptor phosphorylation. Taken together, these findings indicate that ChGn-2 is functionally involved in the progression of atherosclerosis both in its early and advanced stages. Therefore, ChGn-2 may serve as a plausible target to treat atherosclerotic-related diseases in the future.

Activation of neuregulin-4 in adipocytes improves metabolic health by enhancing adipose tissue angiogenesis.

Obesity often causes systemic metabolic disorders in close association with adipose tissue dysfunction. Adipose tissue contains well-developed vasculatures, and obesity mediates vascular rarefaction that causes hypoxia and triggers inflammation in adipose tissue. Adipose tissue-derived neuregulin-4 (Nrg4) is an immerging factor that is critically involved in metabolic homeostasis. We recently identified that Nrg4 is an angiogenic adipokine that plays an important role in maintaining adipose tissue vasculature. Here, we further validated its beneficial role in metabolic health primarily by enhancing adipose tissue angiogenesis. Targeted activation of Nrg4 in adipocytes improved metabolic health in mice under both normal and high fat dietary condition without changes in body weight. Activation of Nrg4 increased blood vessels in white adipose tissue, and ameliorated adipose tissue hypoxia under obese condition. Of note, inhibition of angiogenesis by sugen-treatment abolished the beneficial effects of Nrg4 on systemic metabolic health. Furthermore, targeted inhibition of Nrg4-ErbB signaling in adipose tissue vasculature using prohibitin binding peptide-conjugated nanocarrier abrogated the enhanced adipose tissue angiogenesis, and canceled the improved metabolic health induced by Nrg4 activation. These data further support a crucial role of Nrg4 in maintaining systemic metabolic homeostasis at least partially through enhancing adipose tissue angiogenesis.

Neuregulin-4 is an angiogenic factor that is critically involved in the maintenance of adipose tissue vasculature.

Adipose tissue (AT) contains well-developed vascular networks. Pathological AT expansion often accompany the reduction in AT blood vessels, which further exacerbates adipocyte dysfunction due to hypoxia; however, it remains unclear whether AT vascular rarefaction is simply secondary to adipocyte hypertrophy, or if there is an actively regulated pathway that mediates impaired AT angiogenesis in obesity. We searched for growth factors whose expression in AT is down-regulated in obesity; accordingly, we identified neuregulin-4 (Nrg4), a member of the EGF family of proteins. Nrg4 is highly and preferentially expressed in healthy adipocytes, while its expression was substantially reduced in obesity. Nrg4 activated endothelial angiogenic functions and angiogenesis both in vitro and in vivo. Genetic loss of Nrg4 caused reduction in brown and white AT blood vessels, and induced overweight even while consuming normal chow. Conditional knockout of Nrg4 in brown adipocytes caused blood vessel reduction in brown but not in white AT, and was sufficient to induce obese phenotype. Our data demonstrated that Nrg4 plays a critical role in maintaining AT vasculature and its metabolic functions. Considering the substantial reduction of Nrg4 in obesity, disruption of Nrg4-mediated angiogenesis could be an active mechanism for the obesity-associated vascular rarefaction in AT, and thus Nrg4 is an attracting pharmacotherapeutic target in the prevention and/or treatment of obesity-related metabolic disorders.

Systemic inhibition of Janus kinase induces browning of white adipose tissue and ameliorates obesity-related metabolic disorders.

Browning of white adipose tissue is a promising strategy to tackle obesity. Recently, Janus kinase (JAK) inhibition was shown to induce white-to-brown metabolic conversion of adipocytes in vitro; however effects of JAK inhibition on browning and systemic metabolic health in vivo remain to be elucidated. Here, we report that systemic administration of JAK inhibitor (JAKi) ameliorated obesity-related metabolic disorders. Administration of JAKi in mice fed a high-fat diet increased UCP-1 and PRDM16 expression in white adipose tissue, indicating the browning of white adipocyte. Food intake was increased in JAKi-treated mice, while the body weight and adiposity was similar between the JAKi- and vehicle-treated mice. In consistent with the browning, thermogenic capacity was enhanced in mice treated with JAKi. Chronic inflammation in white adipose tissue was not ameliorated by JAKi-treatment. Nevertheless, insulin sensitivity was well preserved in JAKi-treated mice comparing with that in vehicle-treated mice. Serum levels of triglyceride and free fatty acid were significantly reduced by JAKi-treatment, which is accompanied by ameliorated hepatosteatosis. Our data demonstrate that systemic administration of JAKi has beneficial effects in preserving metabolic health, and thus inhibition of JAK signaling has therapeutic potential for the treatment of obesity and its-related metabolic disorders.

CHST3 and CHST13 polymorphisms as predictors of bosentan-induced liver toxicity in Japanese patients with pulmonary arterial hypertension.

Bosentan, an endothelin receptor antagonist, has been widely used as a first-line drug for the treatment of pulmonary arterial hypertension (PAH). In addition, bosentan is approved for patients with digital ulcers related to systemic sclerosis. Liver dysfunction is a major adverse effect of bosentan and may lead to discontinuation of therapy. The purpose of this study was to identify genomic biomarkers to predict bosentan-induced liver injury. A total of 69 PAH patients were recruited into the study. An exploratory analysis of 1936 single-nucleotide polymorphisms (SNPs) in 231 genes involved in absorption, distribution, metabolism, and elimination of multiple medications using Affimetrix DMET™ (Drug Metabolism Enzymes and Transporters) chips was performed. We extracted 16 SNPs (P < 0.05) using the Jonckheere-Terpstra trend test and multiplex logistic analysis; we identified two SNPs in two genes, CHST3 and CHST13, which are responsible for proteoglycan sulfation and were significantly associated with bosentan-induced liver injury. We constructed a predictive model for bosentan-induced liver injury (area under the curve [AUC]: 0.89, sensitivity: 82.61%, specificity: 86.05%) via receiver operating curve (ROC) analysis using 2 SNPs and 2 non-genetic factors. Two SNPs were identified as potential predictive markers for bosentan-induced liver injury in Japanese patients with pulmonary arterial hypertension. This is the first pharmacogenomics study linking proteoglycan sulfating genes to drug-induced liver dysfunction, a frequently observed clinical adverse effect of bosentan therapy. These results may provide a way to personalize PAH medicine as well as provide novel mechanistic insights to drug-induced liver dysfunction.