Tatsunori Oguchi

NADPH Oxidase Deficiency Exacerbates Angiotensin II–Induced Abdominal Aortic Aneurysms in Mice

Objective—Although nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) is reportedly essential for phagocyte host defenses, it has been found to aggravate atherosclerosis in apolipoprotein E (Apoe)-null mice through excess production of superoxide. We therefore assessed the role of NOX2 in an experimental model of abdominal aortic aneurysm (AAA) and assessed the mechanism of NOX2 action in AAA. Approach and Results—AAA was induced in low-density lipoprotein receptor-null (Ldlr–/–) mice by infusing angiotensin II. Nox2 expression was elevated in the abdominal aortae of these mice during infusion of angiotensin II, with enhanced Nox2 expression mainly because of the recruitment of NOX2-enriched macrophages into AAA lesions. Unexpectedly, systemic Nox2 deficiency promoted AAA development but reduced the level of reactive oxygen species in AAA lesions. Nox2 deficiency stimulated macrophage conversion toward the M1 subset, enhancing expression of interleukin (IL)-1&bgr; and matrix metalloproteinase-9/12 mRNA. Administration of neutralizing antibody against IL-1&bgr; abolished AAA development in Nox2-deficient mice. Bone marrow transplantation experiments revealed that AAA aggravation by Nox2 deficiency is because of bone marrow–derived cells. Isolated bone marrow–derived macrophages from Nox2-null mice could not generate reactive oxygen species. In contrast, IL-1&bgr; expression in peritoneal and bone marrow–derived macrophages, but not in peritoneal neutrophils, was substantially enhanced by Nox2 deficiency. Pharmacological inhibition of Janus kinase/signal transducers and activators of transcription signaling inhibited excess IL-1&bgr; expression in Nox2-deficient macrophages, whereas matrix metalloproteinase-9 secretion was constitutively stimulated via nuclear factor-&kgr;B signals. Conclusions—Nox2 deficiency enhances macrophage secretion of IL-1&bgr; and matrix metalloproteinase-9, disrupting tissue-remodeling functions in AAA lesions. These actions are unfavorable if NOX2 is to serve as a molecular target for AAA.

Sitagliptin Inhibits the Lipopolysaccharide-Induced Inflammation

Sitagliptin Inhibits the Lipopolysaccharide-Induced Inflammation Abstract Objective: Sitagliptin is an anti-diabetic Dipeptidyl peptidase-4 (DPP-4) inhibitor; used worldwide with a well-established evidence base as an effective anti-diabetic therapy and the lowest cost of all DPP-4 inhibitors. Atherosclerosis and inflammation are more common in diabetic patients than in nondiabetic patients, and progression of atherosclerosis contributes to this inflammation. Therefore, anti-inflammatory therapy is important for the prognosis of diabetic patients. Although several reports have investigated the anti-inflammatory mechanisms of sitagliptin in vitro, none of these studies has described its effects on mitogenactivated protein kinase (MAPK) in human umbilical vein endothelial cells (HUVECs) stimulated with lipopolysaccharide (LPS). We assessed the MAPK-dependent anti-inflammatory effects of sitagliptin in HUVECs. Methods: HUVECs (1–2 × 105 cell/mL) were either pretreated with different doses of sitagliptin for 1 h or left untreated. Subsequently, HUVECs were either incubated with lipopolysaccharide (LPS) together with sitagliptin (after treatment) or left untreated. Five hours post incubation, the culture medium was sampled for interleukin (IL)-6. Additionally, intranuclear p65 levels were measured 5 h after simultaneous treatment with LPS and sitagliptin. p38 MAPK levels and PKC activity were measured in the cytosolic fractions 30 min after simultaneous treatment with LPS and sitagliptin. Results: Treatment with LPS alone induced significant IL-6 production compared with untreated control cells. Pretreatment of cells with sitagliptin at all concentrations tested significantly reduced LPS-stimulated IL-6 production. However, after treatment of cells with sitagliptin at any concentration did not inhibit LPS-stimulated IL-6 production. Compared to untreated cells, treatment with 5 nM sitagliptin significantly inhibited LPS-stimulated intranuclear p65 expression, and p38 MAPK phosphorylation. There was no significant difference in PKC activity with LPS or sitagliptin. Conclusion: In HUVECs, sitagliptin elicits its anti-inflammatory effects through MAPK-dependent mechanisms.

Cilostazol suppresses Aβ-induced neurotoxicity in SH-SY5Y cells through inhibition of oxidative stress and MAPK signaling pathway

Alzheimer’s disease (AD) is a slowly progressive form of dementia, characterized by memory impairment and cognitive dysfunction. AD is mainly characterized by the deposition of amyloid β (Aβ) plaques and intracellular neurofibrillary tangles in the brain, along with neuronal degeneration and high levels of oxidative stress. Cilostazol (CSZ) was recently found to suppress the progression of cognitive decline in patients with stable AD receiving acetylcholinesterase inhibitors. This present study aimed to clarify the mechanism by which CSZ protects neurons from degeneration associated with Aβ(1–42). We used Aβ(1–42) to induce neurotoxicity in human neuroblastoma SH-SY5Y cells. Cells were pretreated with CSZ before co-treatment with Aβ. To evaluate the effect of CSZ on oxidative stress, we examined levels of reactive oxygen species (ROS), nicotinamide adenine dinucleotide phosphate oxidase (Nox) activity, mRNA expression of NOX4, and Cu/Zn-Superoxide Dismutase (SOD), as well as apoptosis biomarkers [MTT, (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), caspase-3 and -9 activities and staining of annexin V]. We also assayed the activity of mitogen-activated protein kinases (MAPK): p38 MAPK and extracellular signal-regulated kinase1/2 (ERK1/2), and biomarkers of mitochondrial function (Bcl-2 and Bax), and cyclic adenosine monophosphate response element-binding protein (CREB). Aβ-induced oxidative stress (ROS, NOX4 activity, and expression of NOX mRNA), caspase activation (caspase-3 and -9), and p38 MAPK phosphorylation were suppressed by co-treatment with CSZ, but not by ERK1/2 activation. In addition, pretreatment with CSZ suppressed Aβ-induced apoptosis and increased cell viability via suppression of Bax (a proapoptotic protein), upregulation of Bcl-2 (an antiapoptotic protein) and Cu/Zn-SOD (a superoxide scavenging enzyme), and phosphorylation of CREB. These findings suggested that CSZ could counteract neurotoxicity through multiple mechanisms, one mechanism involving the attenuation of oxidative stress by suppressing NOX activity and Nox mRNA expression in Aβ-induced neurotoxicity and another involving the anti-neurotoxic effect via the ERK1/2/phosphorylated CREB pathway.

A new method for measuring osteoclast formation by electrical impedance.

Osteoclasts are important target cells for osteoporosis treatment. Recently, a real-time cell analysis (RTCA) system was developed to observe cell morphology and adhesion; however, the use of RTCA to study osteoclastogenesis has not been reported. Here, we investigated whether osteoclast formation could be monitored in real-time using RTCA. The cell index determined via electrical impedance using RTCA, and the number of osteoclasts exhibited a significant positive correlation. RTCA was useful for determining the effect of (-)-epigallocatechin-3-gallate on the inhibition of bone resorption. We established a new method of measuring osteoclast formation in real-time using RTCA.

Modified Six Elements Test: Earlier diagnosis of the correlation between motor and executive dysfunction in Parkinson's disease without dementia

In patients with Parkinsons disease, executive deficits are known to correlate with motor dysfunctions, such as gait and postural instability. However executive deficits are sometimes difficult to detect using common frontal assessment batteries. Behavioral Assessment of Dysexecutive Syndrome includes six subtests to evaluate different aspects of executive function required in daily life. Among these the Modified Six Elements Test examines higher levels of executive function with regard to prospective memory and organization of behavior.

Vitamin E-Coated Dialyzer Inhibits Oxidative Stress

Aim: To examine the effects of vitamin E-coated dialyzer on oxidative stress in vitro. Methods: A dialyzer with a synthetic polymer membrane (APS-11SA) and vitamin E-coated dialyzer (VPS-11SA) were connected to a blood tubing line, and U937 cells were circulated in the device. The circulating fluid was collected at 1, 2, 5, 10, 25, and 50 cycles, which are estimated numbers of passes through the dialyzer. Intracellular reactive oxygen species (ROS) production, malondialdehyde (MDA), and Cu/Zn-superoxide dismutase (SOD) were quantified. Results: Intracellular ROS production was increased in the first cycle by APS-11SA and was decreased throughout the experiment by VPS-11SA. Intracellular ROS production in the VPS-11SA device was lower, and MDA levels were decreased. MDA levels were lower during VPS-11SA processing than during APS-11SA processing. Cu/Zn-SOD levels remained unchanged. Conclusion: Our results highlight anti-oxidative-stress effects of a vitamin E-coated dialyzer.

Supratherapeutic concentrations of cilostazol inhibits β-amyloid oligomerization in vitro

Alzheimer disease (AD) is the most common type of dementia, and is currently incurable. The efficacy of existing treatments for AD such as acetylcholinesterase inhibitors is limited to symptom improvement. Research on disease-modifying therapies (DMTs) has conventionally focused on amelioration of CNS pathogenesis. Two neuropathological changes correlate strongly with AD, the appearance of neurofibrillary tangles containing the microtubule-associated protein tau and extracellular amyloid deposits containing amyloid β-protein (Aβ). The aggregation of Aβ is believed to be the key pathogenic event in AD, with oligomeric assemblies thought to be the most neurotoxic form. Inhibitors of oligomer formation, therefore, could be valuable therapeutics for AD patients. The clinical phosphodiesterase type-3 inhibitor cilostazol (CSZ) was recently found to suppress the progression of cognitive decline in patients with stable AD receiving acetylcholinesterase inhibitors. Here we examined the effects of CSZ on in vitro aggregations of Aβ1-40 and Aβ1-42 including oligomerization, using the thioflavin T assay, photo-induced cross-linking of unmodified proteins, and electron microscopy. CSZ (25-100 μM) inhibited Aβ aggregation, especially oligomer formation. Considering that CSZ might be a key molecule for DMTs of AD, it cannot be ruled out that the low concentration of CSZ achievable in patient dosing may display some ant-oligomeric activity in synergy with its known therapeutic effects.