Naoyuki Kimura

miR-29b Participates in Early Aneurysm Development in Marfan Syndrome

Rationale: Marfan syndrome (MFS) is a systemic connective tissue disorder notable for the development of aortic root aneurysms and the subsequent life-threatening complications of aortic dissection and rupture. Underlying fibrillin-1 gene mutations cause increased transforming growth factor-&bgr; (TGF-&bgr;) signaling. Although TGF-&bgr; blockade prevents aneurysms in MFS mouse models, the mechanisms through which excessive TGF-&bgr; causes aneurysms remain ill-defined. Objective: We investigated the role of microRNA-29b (miR-29b) in aneurysm formation in MFS. Methods and Results: Using quantitative polymerase chain reaction, we discovered that miR-29b, a microRNA regulating apoptosis and extracellular matrix synthesis/deposition genes, is increased in the ascending aorta of Marfan (Fbn1C1039G/+) mice. Increased apoptosis, assessed by increased cleaved caspase-3 and caspase-9, enhanced caspase-3 activity, and decreased levels of the antiapoptotic proteins, Mcl-1 and Bcl-2, were found in the Fbn1C1039G/+ aorta. Histological evidence of decreased and fragmented elastin was observed exclusively in the Fbn1C1039G/+ ascending aorta in association with repressed elastin mRNA and increased matrix metalloproteinase-2 expression and activity, both targets of miR-29b. Evidence of decreased activation of nuclear factor &kgr;B, a repressor of miR-29b, and a factor suppressed by TGF-&bgr;, was also observed in Fbn1C1039G/+ aorta. Furthermore, administration of a nuclear factor &kgr;B inhibitor increased miR-29b levels, whereas TGF-&bgr; blockade or losartan effectively decreased miR-29b levels in Fbn1C1039G/+ mice. Finally, miR-29b blockade by locked nucleic acid antisense oligonucleotides prevented early aneurysm development, aortic wall apoptosis, and extracellular matrix deficiencies. Conclusions: We identify increased miR-29b expression as key to the pathogenesis of early aneurysm development in MFS by regulating aortic wall apoptosis and extracellular matrix abnormalities.

A common rejection module (CRM) for acute rejection across multiple organs identifies novel therapeutics for organ transplantation

A set of 11 genes, termed the common rejection module, predicts acute graft rejection in solid organ transplant patients and may help to identify novel drug targets in transplantation.

Influence of patent false lumen on long-term outcome after surgery for acute type A aortic dissection

OBJECTIVE The fate of the dissected distal aorta after surgery for acute type A aortic dissection has not been fully understood. We assessed the influence of a residual patent false lumen on long-term outcomes. METHODS Two hundred eighteen patients underwent emergency surgery for DeBakey type I or IIIb retrograde acute type A aortic dissection (1997-2006). Aortic arch replacement was performed in selected patients whose entry site was in or extended into the aortic arch. In-hospital mortality was 7.3% (16/218), and 193 survivors (mean age 62 years) underwent enhanced computed tomography within 1 month after the operation. These patients were divided into two groups according to the status of the false lumen, whether patent (n = 124) or thrombosed (n = 69). In each group, segment-specific aortic growth rate, distal reoperation, and late survival were examined. RESULTS Growth rate was determined in 139 (72.0%) patients who underwent serial computed tomography. Average growth rate in the patent group was greater than that in the thrombosed group (aortic arch [1.1 vs -0.41 mm per year; P = .005], proximal descending aorta [1.9 vs -0.71 mm per year; P <.001], and distal descending aorta [1.3 vs -0.70 mm per year; P = .002]). However, growth was slow (<1 mm per year) in about 50% of patients in the patent group. There was no significant difference in distal reoperation or late survival between the two groups. CONCLUSIONS The patent false lumen influences postoperative aortic enlargement. However, with careful follow-up, a favorable prognosis is expected even for patients with a residual patent false lumen.

αB-Crystallin Improves Murine Cardiac Function and Attenuates Apoptosis in Human Endothelial Cells Exposed to Ischemia-Reperfusion

BACKGROUND This study investigates the protective effect of exogenous αB-crystallin (CryAB) on myocardial function after ischemia-reperfusion injury. METHODS Mice underwent temporary left anterior descending artery occlusion for 30 minutes. Either CryAB (50 μg) or phosphate-buffered saline (100 μL [n=6, each group]) were injected in the intramyocardial medial and lateral perinfarct zone 15 minutes before reperfusion. Intraperitoneal injections were administered every other day. Left ventricular ejection fraction was evaluated on postoperative day 40 with magnetic resonance imaging. To investigate the effect of CryAB on apoptosis after hypoxia/reoxygenation in vitro, murine atrial cardiomyocytes (HL-1 cells) or human microvascular endothelial cells (HMEC-1) were incubated with either 50 μg CryAB (500 μg /10 mL) or phosphate-buffered saline in a hypoxia chamber for 6, 12, and 24 hours, followed by 30 minutes of reoxygenation at room air. Apoptosis was then assessed by western blot (Bcl-2, free bax, cleaved caspases-3, 9, PARP) and enzyme-linked immunosorbent assay analyses (cytoplasmic histone-associated DNA fragments and caspase-3 activity). RESULTS On postoperative day 40, CryAB-treated mice had a 1.8-fold increase in left ventricular ejection fraction versus control mice (27%±6% versus 15%±4% SD, p<0.005). In vitro, (1) the HL-1 cells showed no significant difference in apoptotic protein expression, cytoplasmic histone-associated DNA fragments, or caspase-3 activity; (2) the HMEC-1 cells had increased but not significant apoptotic protein expression with, however, a significant decrease in cytoplasmic histone-associated DNA fragments (1.5-fold, p<0.01) and caspase-3 activity (2.7-fold, p<0.005). CONCLUSIONS Exogenous CryAB administration significantly improves cardiac function after ischemia-reperfusion injury, in vivo. The protective anti-apoptotic affects of CryAB may target the endothelial cell.

Interleukin-17 Accelerates Allograft Rejection by Suppressing Regulatory T Cell Expansion

Background— Interleukin-17 (IL-17), which is predominantly produced by T helper 17 cells distinct from T helper 1 or T helper 2 cells, participates in the pathogenesis of infectious, autoimmune, and allergic disorders. However, the precise role in allograft rejection remains uncertain. In the present study, we investigated the role of IL-17 in acute allograft rejection using IL-17-deficient mice. Methods and Results— Donor hearts from FVB mice were heterotopically transplanted into either C57BL/6J-IL-17-deficient (IL-17−/−) or -wild-type mice. Allograft survival was significantly prolonged in IL-17−/− recipient mice due to reduced local inflammation accompanied by decreased inflammatory cell recruitment and cytokine/chemokine expression. IL-17−/− recipient mice exhibited decreased IL-6 production and reciprocally enhanced regulatory T cell expansion, suggesting a contribution of regulatory T cells to prolonged allograft survival. Indeed, allografts transplanted into anti-CD25 mAb-treated IL-17−/− recipient mice (regulatory T cell-depleted) developed acute rejection similar to wild-type recipient mice. Surprisingly, we found that gamma delta T cells rather than CD4+ and CD8+ T cells were key IL-17 producers in the allografts. In support, equivalent allograft rejection was observed in Rag-2−/− recipient mice engrafted with either wild-type or IL-17−/− CD4+ and CD8+ T cells. Finally, hearts transplanted into gamma delta T cell-deficient mice resulted in decreased allograft rejection compared with wild-type controls. Conclusions— During heart transplantation, (1) IL-17 is crucial for acceleration of acute rejection; (2) IL-17-deficiency enhances regulatory T cell expansion; and (3) gamma delta T cells rather than CD4+ and CD8+ T cells are a potential source of IL-17. IL-17 neutralization may provide a potential target for novel therapeutic treatment for cardiac allograft rejection.

IL-17 Contributes to the Development of Chronic Rejection in a Murine Heart Transplant Model

BackgroundAlthough interleukin-17 (IL-17) has been reported to participate in the pathogenesis of infectious, autoimmune and allergic disorders, the precise role in allograft rejection remains uncertain. This study illustrates that IL-17 contributes to the pathogenesis of chronic allograft rejection.ResultUtilizing a murine heterotopic heart transplant model system, IL-17-deficient recipient mice had decreased allograft inflammatory cell recruitment, decreased IL-6, MCP-1, and KC production, and reduced graft coronary artery disease (GCAD). Intragraft gamma delta (γδ) T cells appear to be the predominant source of IL-17 production.ConclusionTherefore, IL-17 neutralization may provide a potential target for novel therapeutic treatment for cardiac allograft rejection.

The 17-mm St. Jude Medical Regent Valve Is a Valid Option for Patients With a Small Aortic Annulus

BACKGROUND When aortic valve replacement is performed in patients with a small aortic annulus, prosthesis-patient mismatch is of concern. Such prosthesis-patient mismatch may affect postoperative clinical status and survival. We investigated the outcomes of isolated aortic valve replacement performed with a 17-mm mechanical prosthesis in patients with aortic stenosis. METHODS Twenty-three patients with aortic stenosis (mean age, 74.6 +/- 6.3 years) underwent isolated aortic valve replacement with a 17-mm St. Jude Medical Regent prosthesis. Mean body surface area was 1.41 +/- 0.13 m(2). Preoperative echocardiography yielded a mean aortic valve area of 0.36 +/- 0.10 cm(2)/m(2), a mean left ventricular-aortic pressure gradient of 68.4 +/- 25.3 mm Hg, and a mean left ventricular mass index of 200 +/- 69 g/m(2). RESULTS There was no operative mortality, and there were no valve-related events. Echocardiography at 14.0 +/- 10.0 months after aortic valve replacement showed a significant increase in the mean effective orifice area index (0.95 +/- 0.24 cm(2)/m(2)), decrease in the mean left ventricular-aortic pressure gradient (17.4 +/- 8.2 mm Hg), and decrease in the mean left ventricular mass index (124 +/- 37 cm(2)/m(2)). Prosthesis-patient mismatch (effective orifice area index < 0.85 cm(2)/m(2)) was present in 8 patients at discharge. In these patients as well as in those without prosthesis-patient mismatch, the left ventricular mass index decreased remarkably during follow-up. CONCLUSIONS Aortic valve replacement with a 17-mm Regent prosthesis appears to provide satisfactory clinical and hemodynamic results in patients with a small aortic annulus. Remarkable left ventricular mass regression during follow-up was achieved irrespective of the effective orifice area index at discharge.

Utility of the Penn Classification in Predicting Outcomes of Surgery for Acute Type A Aortic Dissection

The Penn classification, a risk assessment system for acute type A aortic dissection (AAAD), is based on preoperative ischemic conditions. We investigated whether Penn classes predict outcomes after surgery for AAAD. Three hundred fifty-one patients with DeBakey type I AAAD treated surgically, January 1997 to January 2011, were divided into 4 groups per Penn class: Aa (no ischemia, n = 187), Ab (localized ischemia with branch malperfusion, n = 67), Ac (generalized ischemia with circulatory collapse, n = 46), and Abc (localized and generalized ischemia, n = 51). Early and late outcomes were compared between groups. In-hospital mortality was 3% (6 of 187) for Penn Aa, 6% (4 of 67) for Penn Ab, 17% (8 of 46) for Penn Ac, and 22% (11 of 51) for Penn Abc. Multivariate logistic regression analysis showed Penn classes Ac and Abc, operation time >6 hours, and entry in the descending thoracic aorta to be risk factors for in-hospital mortality. Incidences of neurologic, respiratory, and hepatic complications differed between groups. Five-year cumulative survival was 85% in the Penn Aa group, 74% in the Penn Ab group (p = 0.027 vs Penn Aa), 78% in the Penn Ac group, and 67% in the Penn Abc group (p <0.001 vs Penn Aa). In conclusion, morbidity and mortality are high in patients with generalized ischemia. The Penn classification appears to be a useful risk assessment system for AAAD, predictive of outcomes.

Perfusion through the dorsalis pedis artery for acute limb ischemia secondary to an occlusive arterial cannula during percutaneous cardiopulmonary support

Percutaneous cardiopulmonary support (PCPS) is a powerful resuscitation tool for patients in cardiogenic shock. The femoral artery is generally used for arterial access; however, vascular complications, particularly in atherosclerotic arteries, can occur. Although such complications occur infrequently, they can be fatal. We describe the case of a 75-year-old woman who required extended PCPS for cardiogenic shock secondary to coronary spasm after on-pump beating coronary artery bypass grafting. Limb ischemia occurred because of an occlusive cannula, and distal perfusion with a 20G elastic intravenous catheter inserted into the dorsalis pedis artery resolved the ischemia. The catheter was connected to the side port of an oxygenator and provided distal limb perfusion during PCPS. This technique appears to be useful in treating limb ischemia and may have application in patients with arterial occlusive disease who are dependent on mechanical support.

Prevention of transplant coronary artery disease by prenylation inhibitors

BACKGROUND In this study we systematically dissect the prenylation pathway to better define the mechanism behind statin inhibition in chronic allograft rejection in heart transplants, or transplant coronary artery disease (TCAD). METHODS Utilizing a murine heterotopic heart transplant model, animals received daily treatments of either statin or selective isoprenoid blockade inhibitors to block the four major downstream branches of the mevalonate pathway. TCAD was assessed by morphometric analysis at Day 52. Graft-infiltrating cells, cytokine production, smooth muscle cell proliferation and migration and endothelial cell MHC II expression were detected on Day 7. RESULTS Atorvastatin and two prenylation inhibitors, NE-10790 and manumycin A, significantly reduced TCAD lesions compared with untreated animals. Perillyl alcohol treatment resulted in a trend toward decreased luminal narrowing. Finally, zaragozic acid (cholesterol blockade only) did not alter TCAD severity. Statins and prenylation inhibitors reduced inflammatory cell allograft recruitment, but did not always correlate with TCAD reduction. Cytokine production was decreased in recipient spleens in all treatment groups. Both in vitro and in vivo IFN-γ-stimulated MHC II expression was decreased in a dose-dependent manner in the atorvastatin, perillyl alcohol and NE-10790 groups. In vitro smooth muscle cell proliferation was decreased in all treatment groups. Finally, in vitro smooth muscle cell migration was decreased in the atorvastatin, NE-10790 and manumycin A groups only. CONCLUSIONS FPT and GGPT-2 (inhibition) are the key enzymes in the HGM-CoA reductase pathway and most influential in TCAD prevention. TCAD reduction is most closely related to smooth muscle cell migration, but not its anti-inflammatory properties.