Cyp2c44 Gene Disruption Is Associated With Increased Hematopoietic Stem Cells: Implication in Chronic Hypoxia-induced Pulmonary Hypertension

We have recently demonstrated that disruption of the murine cytochrome P450 2c44 gene exacerbates chronic hypoxia-induced pulmonary artery remodeling and hypertension in mice. Subsequently, we serendipitously found that Cyp2c44 gene disruption also increases hematopoietic stem cell (HSC) number in bone marrow and blood. Therefore, the objective of this study was to investigate whether Cyp2c44 disruption regulates HSC phenotype and whether increases in differentiated HSCs contribute to chronic hypoxia-induced remodeling of pulmonary arteries. Our findings demonstrated that lack of a CYP2C44 epoxygenase, which produces epoxyeicosatrienoic acids and hydroxyeicosatetraenoic acids, increases: 1] HSC (CD34+, CD117+, and CD133+) numbers, 2] proangiogenic (CD34+, CD133+, CD34+, CD117+, CD133+) cells, and 3] immunogenic/inflammatory (CD34+, CD11b+, CD133+, CD11b+, F4/80+, CD11b+, and F4/80+ CD11b+) monocytes and macrophages, in bone morrow and blood as compared to wild type mice. Furthermore, we identified increased CD133+ and von Willebrand factor positive cells, which are derived from proangiogenic stem cells, in remodeled and occluded pulmonary arteries of CYP2C44-deficient mice exposed to chronic hypoxia. In conclusion, our results demonstrated that CYP2C44-derived lipid mediators played a critical role in regulating HSCs phenotype, because disruption of Cyp2c44 gene increased differentiated HSCs that potentially contributed to chronic hypoxia-induced pulmonary artery remodeling and occlusion

Evaluation of palliative treatments in unresectable pancreatic cancer

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) presents as unresectable disease in 80% of patients. Limited Australian data exists regarding management and outcome of palliative management for PDAC. This study aims to: (i) identify patients with PDAC being managed with palliative intent; (ii) assess the type of palliative management being used. METHODS: A prospectively maintained pancreatic database at Western Health (2015-2017) was used to identify patient demographics; stage and multidisciplinary decision regarding resectability and operative interventions; palliative care; use of chemotherapy, radiotherapy and; management of exocrine and endocrine insufficiency. Data on chemotherapy use, number of hospital admissions, emergency department attendances and intensive care unit admissions 30 days prior to death were recorded. RESULTS: One-hundred and eleven patients had diagnosis of PDAC, 15% with locally advanced and 45% with metastatic PDAC. Among the locally advanced and metastatic PDAC, 48% received biliary stent insertions, 93% had palliative care referral, 45% received palliative chemotherapy and 10% received radiotherapy. Dietitian referral occurred in 79% and 36% were prescribed with a pancreatic enzyme replacement therapy. Diabetes mellitus was present in 52% of which 31% was new onset. Within 30 days prior to death, 11% patients received palliative chemotherapy, 32% were hospitalized and 11% visited an emergency department more than once. Sixty-five percent died in hospital. CONCLUSION: A high proportion of patients diagnosed with locally advanced and metastatic PDAC received palliative care referrals and appropriate level of end-of-life care. Further prospective studies are necessary, examining the management and impacts of pancreatic insufficiency in this group

EET-Dependent Potentiation of Pulmonary Arterial Pressure: Sex-Different Regulation of Soluble Epoxide Hydrolase

We tested the hypothesis that suppression of epoxyeicosatrienoic acid (EET) metabolism via genetic knockout of the gene for soluble epoxide hydrolase (sEH-KO), or female-specific downregulation of sEH expression, plays a role in the potentiation of pulmonary hypertension. We used male (M) and female (F) wild-type (WT) and sEH-KO mice; the latter have high pulmonary EETs. Right ventricular systolic pressure (RVSP) and mean arterial blood pressure (MABP) in control and in response to in vivo administration of U46619 (thromboxane analog), 14,15-EET, and 14,15-EEZE [14,15-epoxyeicosa-5(z)-enoic acid; antagonist of EETs] were recorded. Basal RVSP was comparable among all groups of mice, whereas MABP was significantly lower in F-WT than M-WT mice and further reduced predominantly in F-KO compared with M-KO mice. U46619 dose dependently increased RVSP and MABP in all groups of mice. The increase in RVSP was significantly greater and coincided with smaller increases in MABP in M-KO and F-WT mice compared with M-WT mice. In F-KO mice, the elevation of RVSP by U46619 was even higher than in M-KO and F-WT mice, associated with the least increase in MABP. 14,15-EEZE prevented the augmentation of U46619-induced elevation of RVSP in sEH-KO mice, whereas 14,15-EET-induced pulmonary vasoconstriction was comparable in all groups of mice. sEH expression in the lungs was reduced, paralleled with higher levels of EETs in F-WT compared with M-WT mice. In summary, EETs initiate pulmonary vasoconstriction but act as vasodilators systemically. High pulmonary EETs, as a function of downregulation or deletion of sEH, potentiate U46619-induced increases in RVSP in a female-susceptible manner

EET Intervention on Wnt1, NOV, and HO-1 Signaling Prevents Obesity-induced Cardiomyopathy in Obese Mice

We have previously reported that epoxyeicosatrienoic acid (EET) has multiple beneficial effects on vascular function; in addition to its antiapoptotic action, it increases insulin sensitivity and inhibits inflammation. To uncover the signaling mechanisms by which EET reduces cardiomyopathy, we hypothesized that EET infusion might ameliorate obesity-induced cardiomyopathy by improving heme oxygenase (HO)-1, Wnt1, thermogenic gene levels, and mitochondrial integrity in cardiac tissues and improved pericardial fat phenotype. EET reduced levels of fasting blood glucose and proinflammatory adipokines, including nephroblastoma overexpressed (NOV) signaling, while increasing echocardiographic fractional shortening and O2 consumption. Of interest, we also noted a marked improvement in mitochondrial integrity, thermogenic genes, and Wnt 1 and HO-1 signaling mechanisms. Knockout of peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha) in EET-treated mice resulted in a reversal of these beneficial effects including a decrease in myocardial Wnt1 and HO-1 expression and an increase in NOV. To further elucidate the effects of EET on pericardial adipose tissues, we observed EET treatment increases in adiponectin, PGC-1alpha, phospho-AMP-activated protein kinase, insulin receptor phosphorylation, and thermogenic genes, resulting in a browning pericardial adipose phenotype under high-fat diets. Collectively, these experiments demonstrate that an EET agonist increased Wnt1 and HO-1 signaling while decreasing NOV pathways and the progression of cardiomyopathy. Furthermore, this report presents a portal into potential therapeutic approaches for the treatment of heart failure and metabolic syndrome.NEW & NOTEWORTHY The mechanism by which EET acts on obesity-induced cardiomyopathy is unknown. Here, we describe a previously unrecognized function of EET infusion that inhibits nephroblastoma overexpressed (NOV) levels and activates Wnt1, hence identifying NOV inhibition and enhanced Wnt1 expression as novel pharmacological targets for the prevention and treatment of cardiomyopathy and heart failure.Listen to this article\u27s corresponding podcast at http://ajpheart.physiology.org/content/early/2017/05/31/ajpheart.00093.2017

Inhibition of soluble epoxide hydrolase increases coronary perfusion in mice.

Roles of soluble epoxide hydrolase (sEH), the enzyme responsible for hydrolysis of epoxyeicosatrienoic acids (EETs) to their diols (DHETs), in the coronary circulation and cardiac function remain unknown. We tested the hypothesis that compromising EET hydrolysis/degradation, via sEH deficiency, lowers the coronary resistance to promote cardiac perfusion and function. Hearts were isolated from wild type (WT), sEH knockout (KO) mice and WT mice chronically treated with t-TUCB (sEH inhibitor), and perfused with constant flow at different pre-loads. Compared to WT controls, sEH-deficient hearts required significantly greater basal coronary flow to maintain the perfusion pressure at 100 mmHg and exhibited a greater reduction in vascular resistance during tension-induced heart work, implying a better coronary perfusion during cardiac performance. Cardiac contractility, characterized by developed tension in response to changes in preload, was potentially increased in sEH-KO hearts, manifested by an enlarged magnitude at each step-wise increase in end-diastolic to peak-systolic tension. 14,15-EEZE (EET antagonist) prevented the adaptation of coronary circulation in sEH null hearts whereas responses in WT hearts were sensitive to the inhibition of NO. Cardiac expression of EET synthases (CYP2J2/2C29) was comparable in both genotypic mice whereas, levels of 14,15-, 11,12- and 8,9-EETs were significantly higher in sEH-KO hearts, accompanied with lower levels of DHETs. In conclusion, the elevation of cardiac EETs, as a function of sEH deficiency, plays key roles in the adaptation of coronary flow and cardiac function

Involvement of Gap Junctions Between Smooth Muscle Cells in Sustained Hypoxic Pulmonary Vasoconstriction Development: A Potential Role for 15-HETE and 20-HETE

In response to hypoxia, the pulmonary artery normally constricts to maintain optimal ventilation-perfusion matching in the lung, but chronic hypoxia leads to the development of pulmonary hypertension. The mechanisms of sustained hypoxic pulmonary vasoconstriction (HPV) remain unclear. The aim of this study was to determine the role of gap junctions (GJs) between smooth muscle cells (SMCs) in the sustained HPV development and involvement of arachidonic acid (AA) metabolites in GJ-mediated signaling. Vascular tone was measured in bovine intrapulmonary arteries (BIPAs) using isometric force measurement technique. Expression of contractile proteins was determined by Western blot. AA metabolites in the bath fluid were analyzed by mass spectrometry. Prolonged hypoxia elicited endothelium-independent sustained HPV in BIPAs. Inhibition of GJs by 18β-glycyrrhetinic acid (18β-GA) and heptanol, nonspecific blockers, and Gap-27, a specific blocker, decreased HPV in deendothelized BIPAs. The sustained HPV was not dependent on Ca(2+) entry but decreased by removal of Ca(2+) and by Rho-kinase inhibition with Y-27632. Furthermore, inhibition of GJs decreased smooth muscle myosin heavy chain (SM-MHC) expression and myosin light chain phosphorylation in BIPAs. Interestingly, inhibition of 15- and 20-hydroxyeicosatetraenoic acid (HETE) synthesis decreased HPV in deendothelized BIPAs. 15-HETE- and 20-HETE-stimulated constriction of BIPAs was inhibited by 18β-GA and Gap-27. Application of 15-HETE and 20-HETE to BIPAs increased SM-MHC expression, which was also suppressed by 18β-GA and by inhibitors of lipoxygenase and cytochrome P450 monooxygenases. More interestingly, 15,20-dihydroxyeicosatetraenoic acid and 20-OH-prostaglandin E2, novel derivatives of 20-HETE, were detected in tissue bath fluid and synthesis of these derivatives was almost completely abolished by 18β-GA. Taken together, our novel findings show that GJs between SMCs are involved in the sustained HPV in BIPAs, and 15-HETE and 20-HETE, through GJs, appear to mediate SM-MHC expression and contribute to the sustained HPV development