Tomoyasu Kadoguchi

Elevated Circulating Levels of Inflammatory Markers in Patients with Acute Coronary Syndrome

Objective. We evaluated inflammatory cytokines and chemokine in peripheral blood mononuclear cells (PBMCs) in patients with either acute coronary syndrome (ACS) or stable coronary artery disease (CAD). Methods. We enrolled 20 ACS patients and 50 stable CAD patients without previous history of ACS who underwent cardiac catheterization. Patients with an estimated glomerular filtration rate of ≤30 mL/min/1.73 m2 and C-reactive protein of ≥1.0 mg/dL were excluded. Blood samples were collected from the patients just before catheterization, and PBMCs were isolated from the whole blood. The levels of inflammatory cytokines and chemokine were measured by using real-time quantitative polymerase chain reaction and immunoassays. Results. The expression of tumor necrosis factor alpha (TNF-α), interleukin- (IL-) 6, IL-10, IL-23A, IL-27, and IL-37 was significantly higher in the ACS group than in the CAD group (P < 0.05). In contrast, the expression of IL-33 was significantly lower in the ACS group than in the CAD group (P < 0.05). The ACS patients had higher plasma levels of TNF-α, IL-6, and IL-10 in the ACS group than in the CAD group. Conclusion. Circulating levels of pro-/anti-inflammatory cytokines, including IL-23A, IL-27, IL-33, and IL-37, may be associated with the pathogenesis of atherosclerosis in ACS patients.

Low Serum Levels of EPA are Associated with the Size and Growth Rate of Abdominal Aortic Aneurysm

Aim: Omega-3 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been reported to reduce the risk of cardiovascular disease. However, whether omega-3 PUFAs are involved in the pathogenesis of abdominal aortic aneurysms (AAA) remains unclear. Methods: We analyzed 67 consecutive patients admitted for the elective surgical repair of AAA. We investigated the association of serum EPA and DHA levels as well as the EPA/AA ratio with the size of AAA assessed using three-dimensional reconstructed computed tomography images. Results: Mean patient age was 70 ± 9 years and 60 patients were male. Serum EPA and DHA levels were 75.2 ± 35.7 µg/mL and 146.1 ± 48.5 µg/mL, respectively. EPA/AA ratio was 0.44 ± 0.22, which was lower than those in healthy Japanese subject and equivalent to those in Japanese patients with coronary artery disease as previously reported. Mean of the maximum AAA diameter was 56.4 ± 8.9 mm, and serum EPA levels and EPA/AA ratio negatively correlated with it (r = −0.32 and r = −0.32, respectively). Multiple liner regression analysis showed that EPA levels were significant independent factor contributing to the maximum AAA diameter. Furthermore, low serum EPA levels and low EPA/AA ratio were significantly associated with the growth rate of AAA diameter (r = −0.43 and r = −0.33, respectively). Conclusion: EPA levels in patients with AAA were relatively low. Low serum EPA levels and EPA/AA ratio were associated with the size and growth rate of AAA.

An Interleukin-6 Receptor Antibody Suppresses Atherosclerosis in Atherogenic Mice

IκBNS is a nuclear IκB protein which negatively regulates nuclear factor-κB activity. We demonstrated that IκBNS deficiency accelerates atherosclerosis in LDL receptor-deficient (LDLr−/−) mice via increased interleukin (IL)-6 production by macrophages. Previous studies showed that the increase in IL-6 might contribute to the development of atherosclerotic lesions. However, whether an anti-mouse IL-6 receptor antibody (MR16-1) can protect atherosclerotic lesions in atherogenic mice remains to be elucidated. We investigated atherosclerotic lesions in LDLr−/− and IκBNS−/−/LDLr−/− mice after 16 weeks consumption of a high-fat diet. All mice received intraperitoneal injections of MR16-1 or phosphate-buffered saline (PBS) (control) once a week during a high-fat diet consumption. Treatment of MR16-1 yielded no adverse systemic effects, and we detected no significant differences in serum cholesterol levels in either group. The atherosclerotic lesions were significantly increased in IκBNS−/−/LDLr−/− compared with LDLr−/− mice (p < 0.01) under treatment of PBS. However, MR16-1 treatment abolished the significant difference of atherosclerotic lesions between IκBNS−/−/LDLr−/− and LDLr−/− mice. Interestingly, MR16-1 also significantly decreased atherosclerotic lesions in LDLr−/− mice compared with PBS treatment (p < 0.05). Immunostaining revealed percent phospho-STAT3-positive cell were significantly decreased in the atherosclerotic lesions of MR16-1 treated both IκBNS−/−/LDLr−/− and LDLr−/− mice compared with PBS-treated mice, indicating MR16-1 could suppress atherosclerotic lesions via the inhibition of IL-6–STAT3 signaling pathway. This study highlights the potential therapeutic benefit of anti-IL-6 therapy in preventing atherogenesis induced by dyslipidemia and/or inflammation.

Inhibition of interleukin-1 suppresses angiotensin II-induced aortic inflammation and aneurysm formation

BACKGROUND Angiotensin II (Ang II) activates components of the inflammatory cascade, which promotes hypertension and development of abdominal aortic aneurysm (AAA). This study aimed to elucidate the effects of an IL-1 receptor antagonist (IL-1Ra) and an anti-IL-1β antibody (01BSUR) on Ang II-induced AAA. METHODS AND RESULTS Male wild-type (WT) and IL-1Ra-deficient (IL-1Ra-/-) mice were infused with Ang II (1000 ng/kg/min) using subcutaneous osmotic pumps for 28 days. Fourteen days post-infusion, both systolic blood pressure (SBP) (Ang II-treated IL-1Ra-/-:149 ± 2 vs. Ang II-treated WT:126 ± 3 mm Hg, p < 0.001) and abdominal aortic width (0.94 ± 0.09 vs. 0.49 ± 0.03 mm, p < 0.001) were significantly higher in IL-1Ra-/- mice than in WT mice. Because 28-day infusion with Ang II in IL-1Ra-/- mice significantly increased the occurrence of fatal aortic rupture (89% vs. 6%, p < 0.0001), both types of mice were infused with Ang II for only 14 days, and histological analyses were performed at 28 days. Interestingly, AAA increased more significantly in IL-1Ra-/- mice than in WT mice (p < 0.001), although SBP did not differ at 28 days in IL-1Ra-/- and WT mice (117 ± 4 vs. 115 ± 3 mm Hg, p = 0.71 (after cessation of Ang II infusion)). Histological analyses showed numerous inflammatory cells around the abdominal aorta in IL-1Ra-/- mice, but not in WT mice. Finally, compared with IgG2a treatment, treatment with 01BSUR decreased Ang II-induced AAA in IL-1Ra-/- mice. CONCLUSIONS The present study demonstrates that inhibition of IL-1β significantly suppresses AAA formation after Ang II infusion, suggesting that suppression of IL-1β may provide an additional strategy to protect against AAA in hypertensive patients.

Possible Role of NADPH Oxidase 4 in Angiotensin II-Induced Muscle Wasting in Mice

Background: Muscle wasting is a debilitating phenotype associated with chronic heart failure (CHF). We have previously demonstrated that angiotensin II (AII) directly induces muscle wasting in mice through the activation of NADPH oxidase (Nox). In this study, we tested the hypothesis that deficiency of NADPH oxidase 4 (Nox4), a major source of oxidative stress, ameliorates AII-induced muscle wasting through the regulation of redox balance. Methods and Results: Nox4 knockout (KO) and wild-type (WT) mice were used. At baseline, there were no differences in physical characteristics between the WT and KO mice. Saline (vehicle, V) or AII was infused via osmotic minipumps for 4 weeks, after which, the WT + AII mice showed significant increases in Nox activity and NOX4 protein compared with the WT + V mice, as well as decreases in body weight, gastrocnemius muscle weight, and myocyte cross-sectional area. These changes were significantly attenuated in the KO + AII mice (27 ± 1 vs. 31 ± 1 g, 385 ± 3 vs. 438 ± 13 mg, and 1,330 ± 30 vs. 2281 ± 150 μm2, respectively, all P < 0.05). The expression levels of phospho-Akt decreased, whereas those of muscle RING Finger-1 (MuRF-1) and MAFbx/atrogin-1 significantly increased in the WT + AII mice compared with the WT + V mice. Furthermore, nuclear factor erythroid-derived 2-like 2 (Nrf2) and the expression levels of Nrf2-regulated genes significantly decreased in the WT + AII mice compared with the WT + V mice. These changes were significantly attenuated in the KO + AII mice (P < 0.05). Conclusion: Nox4 deficiency attenuated AII-induced muscle wasting, partially through the regulation of Nrf2. The Nox4–Nrf2 axis may play an important role in the development of AII-induced muscle wasting.