Hirohide Matsuura

Inhibition of Prolyl Hydroxylase Domain-Containing Protein Suppressed Lipopolysaccharide-Induced TNF-α Expression

Objective—Prolyl hydroxylase domain-containing proteins (PHDs) play pivotal roles in oxygen-sensing system through the regulation of &agr;-subunit of hypoxia-inducible factor (HIF), a key transcription factor governing a large set of gene expression to adapt hypoxia. Although tissue hypoxia plays an essential role in maintaining inflammation, the role of PHDs in the inflammatory responses has not been clearly determined. Here, we investigated the role of PHDs in lipopolysaccharide (LPS)-induced tumor necrosis factor &agr; (TNF-&agr;) induction in macrophages. Methods and Results—Northern blot analysis and ELISA revealed that LPS-induced TNF-&agr; upregulation was strongly suppressed by PHD inhibitors, dimethyloxallyl glycine (DMOG), and TM6008 in RAW264.7 macrophages. DMOG suppressed LPS-induced TNF-&agr; upregulation in HIF-1&agr;–depleted cells and HIF-1&agr; overexpression failed to suppress the induction of TNF-&agr;. DMOG rather suppressed LPS-induced NF-&kgr;B transcriptional activity. Downregulation of Phd1 or Phd2 mRNA by RNA interference partially attenuated LPS-induced TNF-&agr; induction. DMOG also inhibited LPS-induced TNF-&agr; production in peritoneal macrophages as well as human macrophages. Conclusions—PHD inhibition by DMOG or RNA interference inhibited LPS-induced TNF-&agr; upregulation in macrophages possibly through NF-&kgr;B inhibition, which is independent of HIF-1&agr; accumulation. This study suggests that PHDs are positive regulators of LPS-induced inflammatory process, and therefore inhibition of PHD may be a novel strategy for the treatment of inflammatory diseases.

Resveratrol attenuates angiotensin II-induced interleukin-6 expression and perivascular fibrosis

Recent studies have shown that resveratrol (3,5,4′-trihydroxystilbene), a polyphenolic compound found in grapes and red wine, has various beneficial effects on cardiovascular diseases and prolongs the life span of mice fed a high-fat diet. We hypothesized that resveratrol may attenuate vascular inflammatory response induced by angiotensin (Ang) II. We examined the effect of resveratrol on Ang II-induced interleukin (IL)-6 expression in vascular smooth muscle cells (VSMCs). Resveratrol significantly attenuated Ang II-induced IL-6 mRNA expression and IL-6 protein in the supernatant of VSMC in a dose-dependent manner. Resveratrol suppressed the IL-6 gene promoter activity. Resveratrol inhibited the Ang II-induced cAMP-response element-binding protein and nuclear factor-kappa B activity, which are critical for Ang II-induced IL-6 gene activation. An increase in the serum concentration of IL-6 induced by Ang II infusion was attenuated by an oral administration of resveratrol. Resveratrol also inhibited Ang II-induced hypertension and perivascular fibrosis of the heart. Although hydralazine reduced blood pressure level equal to resveratrol, it did not reduce the Ang II-induced IL-6 production and perivascular fibrosis. These data suggest that the inhibition of Ang II-induced vascular inflammation and high blood pressure by resveratrol may contribute, at least in part, to the anti-atherogenic effects of resveratrol.

Prolyl Hydroxylase Domain Protein 2 Plays a Critical Role in Diet-Induced Obesity and Glucose Intolerance

Background— Recent studies suggest that the oxygen-sensing pathway consisting of transcription factor hypoxia-inducible factor and prolyl hydroxylase domain proteins (PHDs) plays a critical role in glucose metabolism. However, the role of adipocyte PHD in the development of obesity has not been clarified. We examined whether deletion of PHD2, the main oxygen sensor, in adipocytes affects diet-induced obesity and associated metabolic abnormalities. Methods and Results— To delete PHD2 in adipocyte, PHD2-floxed mice were crossed with aP2-Cre transgenic mice (Phd2f/f/aP2-Cre). Phd2f/f/aP2-Cre mice were resistant to high-fat diet–induced obesity (36.7±1.7 versus 44.3±2.0 g in control; P<0.01) and showed better glucose tolerance and homeostasis model assessment–insulin resistance index than control mice (3.6±1.0 versus 11.1±2.1; P<0.01). The weight of white adipose tissue was lighter (epididymal fat, 758±35 versus 1208±507 mg in control; P<0.01) with a reduction in adipocyte size. Macrophage infiltration into white adipose tissue was also alleviated in Phd2f/f/aP2-Cre mice. Target genes of hypoxia-inducible factor, including glycolytic enzymes and adiponectin, were upregulated in adipocytes of Phd2f/f/aP2-Cre mice. Lipid content was decreased and uncoupling protein-1 expression was increased in brown adipose tissue of Phd2f/f/aP2-Cre mice. Knockdown of PHD2 in 3T3L1 adipocytes induced a decrease in the glucose level and an increase in the lactate level in the supernatant with upregulation of glycolytic enzymes and reduced lipid accumulation. Conclusions— PHD2 in adipose tissue plays a critical role in the development of diet-induced obesity and glucose intolerance. PHD2 might be a novel target molecule for the treatment of obesity and associated metabolic abnormalities.

Acetylcholinesterase inhibitors attenuate atherogenesis in apolipoprotein E-knockout mice

OBJECTIVE Donepezil, a reversible acetylcholinesterase inhibitor, improves cognitive function of Alzheimers disease. Stimulation of cholinergic system was reported to improve long-term survival of rats with chronic heart failure and to attenuate inflammatory response in mice with lipopolysaccharide-induced sepsis. We sought to determine whether the pharmacological stimulation of cholinergic system by donepezil reduces atherogenesis in apolipoprotein (Apo) E-knockout (KO) mice. METHODS AND RESULTS Male ApoE-KO mice (10-week-old) were fed a high-fat diet and received infusion of angiotensin (Ang) II (490 ng/kg/day). Donepezil or physostigmine was administered for 4 weeks. Oral administration of donepezil (5 mg/kg/day) or infusion of physostigmine (2 mg/kg/day) significantly attenuated atherogenesis (Oil Red O-positive area) without significant changes in heart rate, blood pressure and total cholesterol levels. Administration of donepezil suppressed expression of monocyte chemoattractant protein-1 and tumor necrosis factor-α, NADPH oxidase activity and production of reactive oxygen species in the aorta. CONCLUSION The present study revealed novel anti-oxidative and anti-atherosclerotic effects of pharmacological stimulation of cholinergic system by donepezil. Donepezil may be used as a novel therapeutics for the atherosclerotic cardiovascular diseases.

Deletion of Phd2 in myeloid lineage attenuates hypertensive cardiovascular remodeling

BACKGROUND Hypertension induces cardiovascular hypertrophy and fibrosis. Infiltrated macrophages are critically involved in this process. We recently reported that inhibition of prolyl hydroxylase domain protein 2 (PHD2), which hydroxylates the proline residues of hypoxia-inducible factor-α (HIF-α) and thereby induces HIF-α degradation, suppressed inflammatory responses in macrophages. We examined whether myeloid-specific Phd2 deletion affects hypertension-induced cardiovascular remodeling. METHODS AND RESULTS Myeloid-specific PHD2-deficient mice (MyPHD2KO) were generated by crossing Phd2-floxed mice with LysM-Cre transgenic mice, resulting in the accumulation of HIF-1α and HIF-2α in macrophage. Eight- to ten-week-old mice were given N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, and Angiotensin II (Ang II) infusion. L-NAME/Ang II comparably increased systolic blood pressure in control and MyPHD2KO mice. However, MyPHD2KO mice showed less aortic medial and adventitial thickening, and macrophage infiltration. Cardiac interstitial fibrosis and myocyte hypertrophy were also significantly ameliorated in MyPHD2KO mice. Transforming growth factor-β and collagen expression were decreased in the aorta and heart from MyPHD2KO mice. Echocardiographic analysis showed that left ventricular hypertrophy and reduced ejection fraction induced by L-NAME/Ang II treatment in control mice were not observed in MyPHD2KO mice. Administration of digoxin that inhibits HIF-α synthesis to L-NAME/Ang II-treated MyPHD2KO mice reversed these beneficial features. CONCLUSIONS Phd2 deletion in myeloid lineage attenuates hypertensive cardiovascular hypertrophy and fibrosis, which may be mediated by decreased inflammation- and fibrosis-associated gene expression in macrophages. PHD2 in myeloid lineage plays a critical role in hypertensive cardiovascular remodeling.

Inhibition of MDM2 attenuates neointimal hyperplasia via suppression of vascular proliferation and inflammation

AIMS Tumour protein p53 plays an important role in the vascular remodelling process as well as in oncogenesis. p53 is negatively regulated by murine double minute 2 (MDM2). A recently developed MDM2 inhibitor, nutlin-3, is a non-genotoxic activator of the p53 pathway. So far, the effect of MDM2 inhibition on vascular remodelling has not been elucidated. We therefore investigated the effect of nutlin-3 on neointima formation. METHODS AND RESULTS Nutlin-3 up-regulated p53 and its downstream target p21 in vascular smooth muscle cells (VSMCs). DNA synthesis assay and flow cytometric analysis revealed that nutlin-3 inhibited platelet-derived growth factor (PDGF)-induced VSMC proliferation by cell cycle arrest. This inhibitory effect was abrogated in p53-siRNA-transfected VSMCs. Furthermore, nutlin-3 inhibited PDGF-stimulated VSMC migration. Treatment with nutlin-3 attenuated neointimal hyperplasia at 28 days after vascular injury in mice, associated with up-regulation of p53 and p21. BrdU incorporation was decreased at 14 days after injury in nutlin-3-treated mice. TUNEL assay showed that nutlin-3 did not exaggerate apoptosis of the injured vessels. Infiltration of macrophages and T-lymphocytes and mRNA expression of chemokine (C-C motif) ligand-5, interleukin-6, and intercellular adhesion molecule-1 were decreased in the injured vessels of nutlin-3-treated mice. Nutlin-3 suppressed NF-κB activation in VSMCs, but not in p53-siRNA-transfected VSMCs. CONCLUSIONS The MDM2 antagonist nutlin-3 inhibits VSMC proliferation, migration, and NF-κB activation, and also attenuates neointimal hyperplasia after vascular injury in mice, which is associated with suppression of vascular cell proliferation and an inflammatory response. Targeting MDM2 might be a potential therapeutic strategy for the treatment of vascular proliferative diseases.

Stimulation of α7 nicotinic acetylcholine receptor by AR-R17779 suppresses atherosclerosis and aortic aneurysm formation in apolipoprotein E-deficient mice.

Atherosclerosis is a chronic inflammatory disease. It has been appreciated that vagus nerve inhibits macrophage activation via α7 nicotinic acetylcholine receptor (nAChR), termed the cholinergic anti-inflammatory pathway. We explored the effects of AR-R17779, a selective α7nAChR agonist, on atherosclerosis and aneurysm formation in apolipoprotein E (ApoE)-deficient mice. ApoE-deficient mice were fed a high-fat diet (HFD) and angiotensin II (Ang II) was infused by osmotic minipumps from 10-week-old for 4weeks. AR-R17779 was given in drinking water ad libitum. Oil red O staining of the aorta showed that combined loading of HFD and Ang II induced marked atherosclerosis compared with control mice fed a normal chow. Treatment with AR-R17779 significantly reduced atherosclerotic plaque area and improved survival of mice. Treatment with AR-R17779 also suppressed abdominal aortic aneurysm formation. Quantitative RT-PCR of the aorta revealed that mRNA expression levels of interleukin-1β, interleukin-6 and NOX2 were significantly decreased in AR-R17779-treated mice compared with Ang II+HFD mice. AR-R17779 treatment also reduced blood pressure and serum lipid levels. In conclusion, α7nAChR activation attenuates atherogenesis and aortic abdominal aneurysm formation in ApoE-deficient mice possibly through an anti-inflammatory effect and reduction of blood pressure and lipid levels. Pharmacological activation of α7nAChR may have a therapeutic potential against atherosclerotic vascular diseases through multiple mechanisms.

Inhibition of Prolyl Hydroxylase Domain-Containing Protein Downregulates Vascular Angiotensin II Type 1 Receptor

Inhibition of prolyl hydroxylase domain-containing protein (PHD) by hypoxia stabilizes hypoxia-inducible factor 1 and increases the expression of target genes, such as vascular endothelial growth factor. Although the systemic renin-angiotensin system is activated by hypoxia, the role of PHD in the regulation of the renin-angiotensin system remains unknown. We examined the effect of PHD inhibition on the expression of angiotensin II type 1 receptor (AT1R). Hypoxia, cobalt chloride, and dimethyloxalylglycine, all known to inhibit PHD, reduced AT1R expression in vascular smooth muscle cells. Knockdown of PHD2, a major isoform of PHDs, by RNA interference also reduced AT1R expression. Cobalt chloride diminished angiotensin II–induced extracellular signal–regulated kinase phosphorylation. Cobalt chloride decreased AT1R mRNA through transcriptional and posttranscriptional mechanisms. Oral administration of cobalt chloride (14 mg/kg per day) to C57BL/6J mice receiving angiotensin II infusion (490 ng/kg per minute) for 4 weeks significantly attenuated perivascular fibrosis of the coronary arteries without affecting blood pressure level. These data suggest that PHD inhibition may be beneficial for the treatment of cardiovascular diseases by inhibiting renin-angiotensin system via AT1R downregulation.

Beraprost sodium, a stable prostacyclin analogue, improves insulin resistance in high-fat diet-induced obese mice

Obesity induces hypertrophy of adipocyte resulting in production of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein 1 (MCP1 (CCL2)). These cytokines play an important role in the development of insulin resistance. Beraprost sodium (BPS), a prostaglandin I2 analogue, is reported to attenuate inflammation. In this study, we examined the effect of BPS on glucose metabolism in mice fed a high-fat diet (HFD). Four-week-old C57/B6 male mice were fed a HFD for 12 weeks (HFD group) and the treatment group received oral BPS (300 μg/kg per day) for the same period. Then, glucose metabolism, histological changes, and gene expression of white adipose tissue (WAT) were examined. Body weight was increased, and glucose intolerance and insulin resistance were developed in the HFD group. Treatment with BPS improved glucose tolerance and insulin action without body weight change. Histological analysis of WAT showed an increase in the size of adipocyte and macrophage infiltration in the HFD group, which was attenuated by BPS treatment. BPS reduced HFD-induced expression of MCP1 and TNF-α in WAT. BPS also attenuated hepatic steatosis induced by the HFD. These results suggest that BPS improved glucose intolerance possibly through suppression of inflammatory cytokines in WAT. BPS may be beneficial for the treatment of obesity-associated glucose intolerance.

Acetylcholinesterase inhibitors attenuate angiogenesis.

Donepezil {(RS)-2-[(1-benzyl-4-piperidyl)methyl]-5,6-dimethoxy-2,3-dihydroinden-1-one} is a reversible acetylcholinesterase inhibitor and used for treatment of patients with AD (Alzheimers disease). Recent studies showed that treatment with donepezil reduced production of inflammatory cytokines in PBMCs (peripheral blood mononuclear cells). It was also reported that muscle-derived inflammatory cytokines play a critical role in neovascularization in a hindlimb ischaemia model. We sought to determine whether donepezil affects angiogenesis. A hindlimb ischaemia model was created by unilateral femoral artery ligation. Blood flow recovery examined by laser Doppler perfusion imaging and capillary density by immunohistochemical staining of CD31-positive cells in the ischaemic hindlimb were significantly decreased in donepezil- and physostigmine-treated mice compared with control mice after 2 weeks. Donepezil reduced expression of IL (interleukin)-1β and VEGF (vascular endothelial growth factor) in the ischaemic hindlimb. Intramuscular injections of IL-1β to the ischaemic hindlimb reversed the donepezil-induced VEGF down-regulation and the anti-angiogenic effect. Hypoxia induced IL-1β expression in C2C12 myoblast cells, which was inhibited by pre-incubation with ACh (acetylcholine) or LY294002, a PI3K (phosphoinositide 3-kinase) inhibitor. Donepezil inhibited phosphorylation of Akt [also known as PKB (protein kinase B)], a downstream kinase of PI3K, in the ischaemic hindlimb. These findings suggest that cholinergic stimulation by acetylcholinesterase inhibitors suppresses angiogenesis through inhibition of PI3K-mediated IL-1β induction, which is followed by reduction of VEGF expression. Acetylcholinesterase inhibitor may be a novel anti-angiogenic therapy.