Involvement of growth differentiation factor 15 in paradoxical relationship between body mass index and mortality in patients with suspected or known coronary artery disease; The ANOX Study

Background

Obesity is a well-established risk factor for type 2 diabetes mellitus, hypertension and dyslipidemia, leading to coronary artery disease (CAD). Nevertheless, body mass index (BMI) is inversely associated with cardiovascular (CV) mortality in patients with cardiac disorders, termed “obesity paradox”. However, the underlying mechanism remains unclear.

Purpose

To clarify important factors involved in the pathogenesis of obesity paradox.

Methods

Using data from a multicenter, prospective cohort of 2,418 patients with suspected or known CAD enrolled in the ANOX study, we assessed the relationship between BMI at baseline and the incidence of CV death over 3 years, and investigated the involvement of several endocrine factors which were previously reported to have some roles in obesity and heart diseases, such as adiponectin, N-terminal pro-brain natriuretic peptide (NT-proBNP) and growth differentiation factor 15 (GDF-15), in the relationship between BMI and CV death.

Results

In Kaplan-Meier analyses, the lower quartiles of BMI and the higher quartiles of adiponectin levels were paradoxically associated with the higher cumulative incidence of CV death. To clarify the important factors involved in the paradoxical association between BMI or adiponectin and mortality, we first investigated independent determinants for BMI and adiponectin levels respectively, using multiple stepwise regression analyses among many clinical factors, and then narrow down the prognostic factors commonly associated with BMI and adiponectin, which were age, hemoglobin and NT-proBNP. Interestingly, circulating levels of GDF15 were significantly correlated with NT-proBNP levels, and the presence of anemia raised the gradient of the correlation line in a scatter plot (without anemia, r=0.139, p<0.0001; with anemia, r=0.228, p<0.0001). Moreover, the highest GDF15 quartile showed significantly lower BMI and higher adiponectin levels compared to the lower quartiles (p<0.001 and p<0.001, respectively, by Student t-test). In Cox proportional hazard models, hazard ratios (HRs) of BMI (per 1-unit increase) were 0.90 (95% confidence interval [CI], 0.85–0.96) for CV death. Additional adjustment for hemoglobin, NT-proBNP, adiponectin or GDF15 diminished the statistical significance (HR, 0.92 [95% CI, 0.87–0.99], 0.95 [0.89–1.01], 0.92 [0.87–0.99], or 0.93 [0.87–0.99], respectively).

Conclusions

The lower BMI and the higher adiponectin levels were paradoxically associated with the higher incidence of CV death in patients with CAD. This paradox may be mediated by cardiac endocrine factors induced by cardiac stresses, including GDF-15 in addition to natriuretic peptides.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization.

Serum amyloid A-low-density-lipoprotein complex and mortality in patients with suspected or known coronary artery disease: the ANOX study

Background

Serum amyloid A-low-density-lipoprotein (SAA-LDL) is a complex formed from the oxidative interaction between SAA and LDLs. A relatively small-scale study has shown that circulating SAA-LDL levels may serve as a prognostic marker in patients with stable coronary artery disease (CAD). However, the prognostic value of SAA-LDL should be confirmed in a larger-scale cohort study.

Methods

Using data from a multicenter, prospective cohort of 2416 patients with suspected or known CAD enrolled in the ANOX (Development of Novel Biomarkers Related to Angiogenesis or Oxidative Stress to Predict Cardiovascular Events) study, we assessed the prognostic value of serum levels of SAA-LDL. The primary outcome was all-cause death. The secondary outcomes were cardiovascular death and major adverse cardiovascular events (MACE) defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke. Patients were followed up over 3 years.

Results

Stepwise regression analysis including baseline data on potential clinical confounders (i.e., age, sex, body mass index, hypertension, dyslipidemia, diabetes, current smoking, estimated glomerular filtration rate, the Gensini score, previous myocardial infarction, previous stroke, previous heart failure hospitalization, atrial fibrillation, malignancies, anemia, antihypertensive drug use, statin use, and aspirin use) and established cardiovascular biomarkers (i.e., N-terminal pro-brain natriuretic peptide, high-sensitivity cardiac troponin I [hs-cTnI], and high-sensitivity C-reactive protein [hs-CRP]) revealed that independent determinants of SAA-LDL levels were female sex, dyslipidemia, the Gensini score, absence of statin use, hs-cTnI, and hs-CRP. After adjusting for potential clinical confounders and established cardiovascular biomarkers, the highest quartile of SAA-LDL levels (vs. the lowest quartile) was significantly associated with the incidence of all-cause death (hazard ratio [HR], 1.51; 95% confidence interval [CI], 1.02–2.26), but not with that of cardiovascular death (HR, 1.11; 95% CI, 0.59–2.10) or MACE (HR, 1.57; 95% CI, 0.97–2.57). Stratified analyses revealed that this association was pronounced in patients with low hs-cTnI (<75th percentile) (HR, 1.85; 95% CI, 1.06–3.30) and in patients with low hs-CRP levels (≤1.0 mg/L) (HR, 2.30; 95% CI, 1.17–4.79).

Conclusions

Elevated SAA-LDL levels were independently associated with the risk of all-cause death in patients with suspected or known CAD. The SAA-LDL level appears to serve as a prognostic biomarker for risk stratification in relatively low-risk patients with low hs-cTnI (<75th percentile) or low hs-CRP (≤1.0 mg/L).

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization.

Impact of atrial fibrillation on soluble fms-like tyrosine kinase-1 and cardiovascular events in patients with suspected or known coronary artery disease: the EXCEED-J study

Background

Soluble fms-like tyrosine kinase-1 (sFlt-1), a vascular endothelial growth factor (VEGF) antagonist, has been suggested as a marker of endothelial dysfunction. Circulating sFlt-1 levels are associated with adverse outcomes in patients with preeclampsia, chronic kidney disease, and heart failure. Atrial fibrillation (AF) and coronary artery disease (CAD) are both associated with endothelial dysfunction. However, whether sFlt-1 can predict cardiovascular (CV) events and whether AF modifies the relationship between sFlt-1 and CV events in patients with suspected or known CAD are unknown.

Methods

We performed a nationwide, multicenter, prospective cohort study to determine the prognostic value of sFlt-1 and other biomarkers in patients with suspected or known CAD undergoing elective angiography. Heparin-free fasting serum was collected from the peripheral vein to determine levels of sFlt-1, VEGF, placental growth factor, cystatin C, neutrophil gelatinase-associated lipocalin, N-terminal pro-brain natriuretic peptide (NT-proBNP), high-sensitivity cardiac troponin-I (hs-cTnI), and high-sensitivity C-reactive protein (hs-CRP). The primary outcome was 3-point major adverse CV events (3P-MACE) defined as a composite of CV death, nonfatal myocardial infarction, and nonfatal stroke. The secondary outcomes were all-cause death, CV death, and 5P-MACE defined as a composite of 3P-MACE, heart failure hospitalization, and coronary/peripheral artery revascularization.

Results

3311 patients were consecutively enrolled between Nov 2013 and May 2017. After excluding 56 ineligible patients, 3255 patients (324 AF and 2931 non-AF) were followed up over 3 years (follow-up rate, 99%). During the follow-up, 156 patients developed 3P-MACE, 215 died from any cause, 82 died from cardiovascular disease, and 1361 developed 5P-MACE. The sFlt-1 level was significantly higher in AF compared to non-AF patients (p<0.001). Stepwise regression analysis revealed that the sFlt-1 level was independently associated with AF. After adjusting for potential clinical confounders, serum levels of sFlt-1, NT-proBNP, hs-cTnI and cystatin C, but not other biomarkers, were significantly associated with 3P-MACE in the entire cohort. These associations were still significant in non-AF patients, whereas only the sFlt-1 level was significantly associated with 3P-MACE in AF patients. Serum levels of sFlt-1, but not other biomarkers, were also significantly associated with CV death in AF patients. Among the biomarkers, only the hs-CRP level was significantly associated with all-cause death, and no biomarker was significantly associated with 5P-MACE in AF patients. Furthermore, sFlt-1 provided an incremental prognostic information for 3P-MACE to the model with potential clinical confounders in AF, but not in non-AF patients.

Conclusions

Serum levels of sFlt-1 were significantly associated with 3P-MACE in patients with suspected or known CAD. This association was pronounced in AF patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The EXCEED-J study is supported by Health Labour Sciences Research Grant (2013-2014), AMED (2015-2017, Grant Number JP17ek0210008) and Grant-in-Aid for Clinical Research from the National Hospital Organization (2018-2020).

Internal jugular vein thrombosis and pulmonary thromboembolism after head and neck reconstructive surgery

BACKGROUND

Free flap failure secondary to internal jugular vein thrombosis (IJVT) is a significant complication after head and neck reconstructive surgery. A consensus has not yet been reached among reconstructive surgeons regarding the treatment of IJVT.

METHODS

We retrospectively evaluated the incidence of IJVT in 118 patients who underwent free flap reconstruction at Hyogo Cancer Center, Akashi, Japan. The occurrence of IJVT-related flap circulation crisis and pulmonary thromboembolism (PTE) was studied. This study was approved by the institutional ethics committee, and written informed consent was obtained from each patient.

RESULTS

From 118 patients who underwent head and neck reconstructive surgery, we included 116 internal jugular veins (IJVs) preserved after neck dissection in the present study. IJVT was confirmed in 25 (21.6%) IJVs from 23 patients. One patient (0.8%) developed venous congestion due to IJVT, which resulted in total flap necrosis. Two patients (1.7%) exhibited PTE associated with IJVT. They were treated with direct oral anticoagulants for 3 months and were discharged without any sequelae.

CONCLUSION

Our results suggest that IJVT after head and neck reconstructive surgery caused not only flap circulation crisis but also PTE. Reconstructive surgeons should be aware of the potential risks due to serious complications associated with IJVT.

Impact of glucose tolerance status on the relationship between vascular endothelial growth factor D and mortality in patients with suspected coronary artery disease: a subanalysis of the ANOX study

Background

Vascular endothelial growth factor D (VEGF-D) is a secreted glycoprotein that can act as lymphangiogenic and angiogenic growth factors through binding to its specific receptors, VEGFR-3 and VEGFR-2. VEGF-D signaling via VEGFR-3 plays an important role in lipoprotein metabolisms which may contribute to coronary artery disease (CAD). We recently reported that serum levels of VEGF-D are independently associated with mortality in patients with suspected or known CAD. However, the impact of glucose tolerance status on the relationship between VEGF-D and mortality in patients with suspected CAD is unclear.

Methods

Serum VEGF-D levels were measured in 1,717 patients with suspected CAD undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict CV events (ANOX) study, and followed up for 3 years. After excluding 67 patients with no HbA1c data, 1,650 patients were divided into 3 groups according to the glucose tolerance status: diabetes (DM, n=693), prediabetes (preDM, n=541) defined as an HbA1c of 5.7 to 6.4%, and normal glucose tolerance (NGT, n=416) defined as an HbA1c of 5.6% or less. The outcomes were total death, CV death, and major adverse CV events (MACE) defined as a composite of CV death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 80 DM, 45 preDM, and 30 NGT patients died from any cause, 24 DM, 13 preDM, and 12 NGT died from CV disease, and 54 DM, 30 preDM, and 19 NGT developed MACE. After adjustment for established risk factors, VEGF-D levels were significantly associated with total death (hazard ratio [HR] for 1-SD increase, 1.28; 95% confidence interval [CI], 1.12–1.47), but not with CV death (HR, 1.20; 95% CI, 0.93–1.52) or MACE (HR, 1.23; 95% CI, 0.997–1.48) in DM; VEGF-D levels were not significantly associated with total death (HR, 0.97; 95% CI, 0.70–1.34), CV death (HR, 1.39; 95% CI, 0.92–2.11), or MACE (HR, 1.09; 95% CI, 0.74–1.50) in preDM; VEGF-D levels were not significantly associated with total death (HR, 1.34; 95% CI, 0.98–1.84), CV death (HR, 1.32; 95% CI, 0.78–2.13), or MACE (HR, 1.01; 95% CI, 0.66–1.46) in NGT. Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of VEGF-D levels further improved the prediction of total death (P=0.040 for continuous net reclassification improvement [NRI], P=0.007 for integrated discrimination improvement [IDI]), but not that of CV death or MACE in DM, while it did not significantly improved the prediction of total death, CV death, or MACE either in preDM or in NGT.

Conclusions

The VEGF-D level was independently associated with total death in DM, but not in preDM or in NGT. The relationship between VEGF-D and total mortality may depend on the presence of DM in patients with suspected CAD.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization.

Impact of anemia on the relationship between vascular endothelial growth factor C and mortality in patients with suspected or known coronary artery disease: a subanalysis of the ANOX study

Background

The lymphatic system has been suggested to play an important role in cholesterol metabolism and cardiovascular (CV) disease. Recently, we demonstrated that serum levels of vascular endothelial growth factor C (VEGF-C), a central player of lymphangiogenesis, are inversely and independently associated with the risk of all-cause mortality in patients with suspected or known coronary artery disease (CAD). However, the impact of anemia on the relationship between VEGF-C and mortality in those patients is unclear.

Methods

Serum VEGF-C levels were measured in 2,418 patients with suspected or known CAD undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict CV events (ANOX) study, and followed up for 3 years. Anemia was defined as a hemoglobin level of less than 13 g/dL in men and <12 g/dL in women. Patients were divided into 2 groups according to the presence (anemic, n=882) or absence (non-anemic, n=1,536) of anemia. The primary outcome was all-cause death. The secondary outcomes were CV death, and major adverse CV events (MACE) defined as a composite of CV death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 164 anemic and 90 non-anemic patients died from any cause, 64 anemic and 24 non-anemic patients died from CV disease, and 96 anemic and 69 non-anemic patients developed MACE. After adjustment for established risk factors, VEGF-C levels were significantly and inversely associated with all-cause death (hazard ratio [HR] for 1-SD increase, 0.71; 95% confidence interval [CI], 0.59–0.84), CV death (HR, 0.60; 95% CI, 0.44–0.79), and MACE (HR, 0.76; 95% CI, 0.60–0.95) in anemic, while VEGF-C levels were not significantly associated with all-cause death (HR, 0.87; 95% CI, 0.69–1.11), CV death (HR, 1.32; 95% CI, 0.85–1.93), or MACE (HR, 1.12; 95% CI, 0.87–1.42) in non-anemic patients. Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of VEGF-C levels further improved the prediction of all-cause death (P<0.001 for continuous net reclassification improvement [NRI], P=0.006 for integrated discrimination improvement [IDI]) and CV death (P<0.001 for NRI, P=0.005 for IDI), but not that of MACE (P=0.021 for NRI, P=0.059 for IDI) in anemic, whereas the addition of VEGF-C levels did not improved the prediction of all-cause death (P=0.234 for NRI, P=0.415 for IDI), CV death (P=0.190 for NRI, P=0.392 for IDI) or MACE (P=0.897 for NRI, P=0.128 for IDI) in non-anemic patients.

Conclusions

The VEGF-C level was inversely and independently associated with all-cause and CV mortality in anemic, but not in non-anemic patients with suspected or known CAD. The inverse relationship between VEGF-C and mortality may depend on the presence of anemia.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization.

Impact of chronic kidney disease on the relationship between vascular endothelial growth factor C and mortality in patients with suspected coronary artery disease: a subanalysis of the ANOX study

Background

The lymphatic system has been suggested to play an important role in cholesterol metabolism and cardiovascular (CV) disease. Recently, we demonstrated that serum levels of vascular endothelial growth factor C (VEGF-C), a central player of lymphangiogenesis, are inversely and independently associated with the risk of all-cause mortality in patients with suspected or known coronary artery disease (CAD). However, the impact of chronic kidney disease (CKD) on the relationship between VEGF-C and mortality in patients with suspected CAD is unclear.

Methods

Serum VEGF-C levels were measured in 1,717 patients with suspected but no history of CAD undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict CV events (ANOX) study, and followed up for 3 years. Patients were divided into 2 groups according to the presence (CKD, n=674) or absence (non-CKD, n=1,043) of CKD. The primary outcome was all-cause death. The secondary outcomes were CV death, and major adverse CV events (MACE) defined as a composite of CV death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 95 CKD and 66 non-CKD patients died from any cause, 37 CKD and 13 non-CKD died from CV disease, and 61 CKD and 43 non-CKD developed MACE. After adjustment for established risk factors, VEGF-C levels were significantly and inversely associated with all-cause death (hazard ratio [HR] for 1-SD increase, 0.72; 95% confidence interval [CI], 0.57–0.90) and CV death (HR, 0.69; 95% CI, 0.48–0.97), but not with MACE (HR, 0.78; 95% CI, 0.60–1.03) in CKD, while VEGF-C levels were significantly and inversely associated with all-cause death (HR, 0.69; 95% CI, 0.52–0.91), but not with CV death (HR, 0.91; 95% CI, 0.50–1.66) or MACE (HR, 1.09; 95% CI, 0.81–1.44) in non-CKD. Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of VEGF-C levels further improved the prediction of all-cause death (P=0.047 for continuous net reclassification improvement [NRI], P=0.048 for integrated discrimination improvement [IDI]), but not that of CV death (P=0.016 for NRI, P=0.245 for IDI) or MACE (P=0.166 for NRI, P=0.311 for IDI) in CKD, whereas the addition of VEGF-C levels did not improve the prediction of all-cause death (P=0.053 for NRI, P=0.012 for IDI), CV death (P=0.864 for NRI, P=0.602 for IDI) or MACE (P=0.999 for NRI, P=0.154 for IDI) in non-CKD.

Conclusions

The VEGF-C level inversely and independently predicted all-cause mortality in CKD, but not in non-CKD patients with suspected CAD. The inverse relationship between VEGF-C and all-cause mortality in patients with suspected CAD seems to be remarkable in the presence of CKD.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization.

Impact of anemia on the relationships of growth differentiation factor 15 with mortality and cardiovascular events in patients with suspected or known coronary artery disease: the ANOX study

Background

Growth differentiation factor 15 (GDF-15) is a stress-responsive cytokine that plays an important role in the regulation of the inflammatory response, growth and cell differentiation. An elevated GDF-15 was found in various conditions including anemia and stable coronary artery disease (CAD), and it was reported to predict mortality and cardiovascular (CV) events in general population and in patients with established CAD. However, the impact of anemia on the relationships of GDF-15 with mortality and CV events in patients with suspected or known CAD is unclear.

Methods

Serum GDF-15 levels were measured in 2,418 patients with suspected or known CAD undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict CV events (ANOX) study, and followed up for 3 years. Anemia was defined as a hemoglobin level of less than 13 g/dL in men and <12 g/dL in women. Patients were divided into 2 groups according to the presence (anemic, n=882) or absence (non-anemic, n=1,536) of anemia. The primary outcome was all-cause death. The secondary outcomes were CV death, and major adverse CV events (MACE) defined as a composite of CV death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 164 anemic and 90 non-anemic patients died from any cause, 64 anemic and 24 non-anemic patients died from CV disease, and 96 anemic and 69 non-anemic patients developed MACE. After adjustment for established risk factors, GDF-15 levels were significantly associated with all-cause death (hazard ratio [HR] for 1-SD increase, 1.75; 95% confidence interval [CI], 1.51–2.04), CV death (HR, 1.67; 95% CI, 1.30–2.13), and MACE (HR, 1.46; 95% CI, 1.18–1.81) in anemic, while GDF-15 levels were also significantly associated with all-cause death (HR, 1.47; 95% CI, 1.27–1.69), CV death (HR, 1.56; 95% CI, 1.18–1.99), and MACE (HR, 1.25; 95% CI, 1.004–1.50) in non-anemic patients. Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of GDF-15 levels further improved the prediction of all-cause death (P<0.001 for continuous net reclassification improvement [NRI], P<0.001 for integrated discrimination improvement [IDI]), CV death (P=0.026 for NRI, P=0.023 for IDI), and MACE (P=0.025 for NRI, P=0.042 for IDI) in anemic, whereas it did not improved the prediction of all-cause death (P=0.072 for NRI, P=0.079 for IDI), CV death (P=0.289 for NRI, P=0.179 for IDI) or MACE (P=0.397 for NRI, P=0.230 for IDI) in non-anemic patients.

Conclusions

The GDF-15 level significantly improved the prediction of all-cause death, CV death, and MACE in anemic, but not in non-anemic patients with suspected or known CAD. The relationships of GDF-15 with mortality and CV events seem to be remarkable in the presence of anemia.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization.

Impact of smoking status on the relationships of growth differentiation factor 15 with mortality and cardiovascular events in patients with suspected or known coronary artery disease: the ANOX study

Background

Growth differentiation factor 15 (GDF-15) is a stress-responsive cytokine that plays an important role in the regulation of the inflammatory response, growth and cell differentiation. An elevated GDF-15 was found in various conditions including cigarette smoking and stable coronary artery disease (CAD), and it was reported to predict mortality and cardiovascular (CV) events in general population and in patients with established CAD. However, the impact of smoking status on the relationships of GDF-15 with mortality and CV events in patients with suspected or known CAD is unclear.

Methods

Serum GDF-15 levels were measured in 2,418 patients with suspected or known CAD undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict CV events (ANOX) study, and followed up for 3 years. Patients were divided into 3 groups according to the smoking status: current (n=428), past (n=1,035), and never smokers (n=955). The outcomes were total death, CV death, and major adverse CV events (MACE) defined as a composite of CV death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 48 current, 120 past, and 86 never smokers died from any cause, 17 current, 47 past, and 24 never smokers died from CV disease, and 35 current, 80 past, and 50 never smokers developed MACE. After adjustment for established risk factors, GDF-15 levels were significantly associated with total death (hazard ratio [HR] for 1-SD increase, 1.30; 95% confidence interval [CI], 1.03–1.65), but not with CV death (HR, 1.09; 95% CI, 0.69–1.62) or MACE (HR, 0.95; 95% CI, 0.64–1.34) in current smokers; GDF-15 levels were significantly associated with total death (HR, 1.73; 95% CI, 1.46–2.05) and CV death (HR, 1.41; 95% CI, 1.09–1.85), but not with MACE (HR, 1.20; 95% CI, 0.96–1.48) in past smokers; GDF-15 levels were significantly associated with total death (HR, 1.62; 95% CI, 1.32–1.95), CV death (HR, 1.76; 95% CI, 1.22–2.46), and MACE (HR, 1.64; 95% CI, 1.27–2.07) in never smokers. Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of GDF-15 levels further improved the prediction of total death (P<0.001 for continuous net reclassification improvement [NRI], P=0.001 for integrated discrimination improvement [IDI]) and MACE (P<0.001 for NRI, P=0.045 for IDI), but not that of CV death, in never smokers, while it did not significantly improved the prediction of total death, CV death, or MACE either in current or in past smokers.

Conclusions

The GDF-15 level was independently associated with total death and MACE in never, but not in current or past smokers with suspected or known CAD. The relationships of GDF-15 with mortality and CV events seem to be attenuated by the presence of current and past smoking.

Funding Acknowledgement

Type of funding source: Public Institution(s). Main funding source(s): The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization.

P3639Vascular endothelial growth factor-C and mortality in patients with suspected but no history of coronary heart disease: a subanalysis of the ANOX study

Background

The lymphatic system has been suggested to play an important role in cholesterol metabolism and cardiovascular disease. Recently, we demonstrated that serum levels of vascular endothelial growth factor-C (VEGF-C), a central player of lymphangiogenesis, are inversely and independently associated with the risk of all-cause mortality in patients with suspected or known coronary heart disease (CHD). However, the prognostic value of VEGF-C in patients with suspected but no history of CHD is still unclear.

Methods

Serum VEGF-C levels were measured in 1,717 patients with suspected but no history of CHD undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict cardiovascular events (ANOX) study, and followed up for 3 years. The primary outcome was all-cause death. The secondary outcomes were cardiovascular death, and major adverse cardiovascular events (MACE) defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 161 patients died from any cause, 50 died from cardiovascular disease, and 104 developed MACE. After adjustment for established risk factors, VEGF-C levels were significantly and inversely associated with all-cause death (hazard ratio [HR] for 1-SD increase, 0.69; 95% confidence interval [CI], 0.58–0.83) and cardiovascular death (HR, 0.72; 95% CI, 0.52–0.998), but not with MACE (HR, 0.91; 95% CI, 0.74–1.13). Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin-I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of VEGF-C levels further improved the prediction of all-cause death (continuous net reclassification improvement [NRI], 0.282; 95% CI, 0.121–0.443; P<0.001; integrated discrimination improvement [IDI], 0.009; 95% CI, 0.003–0.016; P=0.005), but not that of cardiovascular death (NRI, 0.178; 95% CI, r=−0.103–0.458; P=0.214; IDI, 0.004; 95% CI, r=−0.002–0.009; P=0.194) or MACE (NRI, 0.037; 95% CI, r=−0.162–0.235; P=0.717; IDI, 0.000; 95% CI, r=−0.0004–0.0005; P=0.872).

Conclusions

In patients with suspected but no history of CHD undergoing elective coronary angiography, a low VEGF-C value may predict all-cause mortality independent of established risk factors and cardiovascular biomarkers.

Acknowledgement/Funding

The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization

5195Growth differentiation factor-15 and mortality in suspected or known coronary heart disease patients with diabetes: a subanalysis of the ANOX study

Background

Diabetes is a risk factor for coronary heart disease (CHD), but further risk stratification in patients with diabetes is necessary to improve the prediction and prevention of cardiovascular events and deaths. Growth differentiation factor-15 (GDF-15) is a stress-responsive cytokine, which plays an important role in the regulation of the inflammatory response, growth and cell differentiation. Elevated GDF-15 was found in various diseases including diabetes and stable CHD, and was reported to predict mortality and cardiovascular events in general or established CHD population. However, the prognostic value of GDF-15 in suspected or known CHD patients with diabetes is unknown.

Methods

Serum GDF-15 levels were measured in 1,087 suspected or known CHD patients with diabetes undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict cardiovascular events (ANOX) study, and followed up for 3 years. The primary outcome was all-cause death. The secondary outcomes were cardiovascular death, and major adverse cardiovascular events (MACE) defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 147 patients died from any cause, 47 died from cardiovascular disease, and 94 developed MACE. After adjustment for established risk factors, GDF-15 levels were significantly associated with all-cause death (hazard ratio [HR] for 1-SD increase, 1.66; 95% confidence interval [CI], 1.48–1.86), cardiovascular death (HR, 1.63; 95% CI, 1.34–1.99), and MACE (HR, 1.41; 95% CI, 1.20–1.65). Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin-I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of GDF-15 levels further improved the prediction of all-cause death (continuous net reclassification improvement [NRI], 0.344; 95% CI, 0.172–0.517; P<0.001; integrated discrimination improvement [IDI], 0.049; 95% CI, 0.026–0.072; P<0.001), but not that of cardiovascular death (NRI, −0.013; 95% CI, −0.300–0.274; P=0.931; IDI, 0.023; 95% CI, 0.003–0.043; P=0.026) or MACE (NRI, 0.059; 95% CI, −0.151–0.268; P=0.583; IDI, 0.005; 95% CI, −0.004–0.015; P=0.244).

Conclusions

In suspected or known CHD patients with diabetes undergoing elective coronary angiography, elevated GDF-15 levels may predict all-cause mortality independent of established risk factors and cardiovascular biomarkers.

Acknowledgement/Funding

The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization.

P5529Vascular endothelial growth factor-D and mortality in suspected or known coronary heart disease patients with diabetes: a subanalysis of the ANOX study

Background

Diabetes is a risk factor for coronary heart disease (CHD), but further risk stratification in patients with diabetes is necessary to improve the prediction and prevention of cardiovascular events and deaths. Vascular endothelial growth factor-D (VEGF-D) is a secreted glycoprotein that can act as lymphangiogenic and angiogenic growth factors through binding to its specific receptors, VEGFR-3 (Flt-4) and VEGFR-2 (KDR/Flk-1). VEGF-D signaling via VEGFR-3 plays an important role in lipoprotein metabolisms which may contribute to CHD. VEGF-D signaling has been used as a therapeutic target of human diseases such as lymphangioleiomyomatosis and refractory angina. Furthermore, in clinical settings, the VEGF-D level is already established as a diagnostic biomarker for lymphangioleiomyomatosis. However, the prognostic value of VEGF-D in suspected or known CHD patients with diabetes is unknown.

Methods

Serum VEGF-D levels were measured in 1,087 suspected or known CHD patients with diabetes undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict cardiovascular events (ANOX) study, and followed up for 3 years. The primary outcome was all-cause death. The secondary outcomes were cardiovascular death, and major adverse cardiovascular events (MACE) defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 147 patients died from any cause, 47 died from cardiovascular disease, and 94 developed MACE. After adjustment for established risk factors, VEGF-D levels were significantly associated with all-cause death (hazard ratio [HR] for 1-SD increase, 1.34; 95% confidence interval [CI], 1.21–1.47), cardiovascular death (HR, 1.40; 95% CI, 1.18–1.62), and MACE (HR, 1.22; 95% CI, 1.07–1.40). Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin-I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of VEGF-D levels further improved the prediction of all-cause death (continuous net reclassification improvement [NRI], 0.258; 95% CI, 0.088–0.429; P=0.003; integrated discrimination improvement [IDI], 0.013; 95% CI, 0.002–0.024; P=0.022), but not that of cardiovascular death (NRI, 0.046; 95% CI, −0.245–0.336; P=0.759; IDI, 0.013; 95% CI, −0.005–0.031; P=0.146) or MACE (NRI, 0.064; 95% CI, −0.146–0.274; P=0.552; IDI, 0.001; 95% CI, −0.002–0.004; P=0.557).

Conclusions

In suspected or known CHD patients with diabetes undergoing elective coronary angiography, elevated VEGF-D levels may predict all-cause mortality independent of established risk factors and cardiovascular biomarkers.

Acknowledgement/Funding

The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization

P5526Vascular endothelial growth factor-D and mortality in suspected or known coronary heart disease patients with chronic kidney disease: a subanalysis of the ANOX study

Background

Chronic kidney disease (CKD) is an independent risk factor for the development and progression of coronary heart disease (CHD). Vascular endothelial growth factor-D (VEGF-D) is a secreted glycoprotein that can act as lymphangiogenic and angiogenic growth factors through binding to its specific receptors, VEGFR-3 (Flt-4) and VEGFR-2 (KDR/Flk-1). VEGF-D signaling via VEGFR-3 plays an important role in lipoprotein metabolisms which may contribute to CHD. VEGF-D signaling has been used as a therapeutic target of human diseases such as lymphangioleiomyomatosis and refractory angina. Furthermore, in clinical settings, the VEGF-D level is already established as a diagnostic biomarker for lymphangioleiomyomatosis. However, the prognostic value of VEGF-D in suspected or known CHD patients with CKD is unknown.

Methods

Serum VEGF-D levels were measured in 999 suspected or known CHD patients with CKD undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict cardiovascular events (ANOX) study, and followed up for 3 years. The primary outcome was all-cause death. The secondary outcomes were cardiovascular death, and major adverse cardiovascular events (MACE) defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 154 patients died from any cause, 61 died from cardiovascular disease, and 96 developed MACE. After adjustment for established risk factors, VEGF-D levels were significantly associated with all-cause death (hazard ratio [HR] for 1-SD increase, 1.41; 95% confidence interval [CI], 1.27–1.56), cardiovascular death (HR, 1.48; 95% CI, 1.28–1.71), and MACE (HR, 1.34; 95% CI, 1.18–1.53). Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin-I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of VEGF-D levels further improved the prediction of all-cause death (continuous net reclassification improvement [NRI], 0.272; 95% CI, 0.100–0.445; P=0.002; integrated discrimination improvement [IDI], 0.015; 95% CI, 0.003–0.027; P=0.013), but not that of cardiovascular death (NRI, 0.230; 95% CI, −0.029 to 0.488; P=0.082; IDI, 0.012; 95% CI, −0.007 to 0.031; P=0.207) or MACE (NRI, 0.102; 95% CI, −0.106 to 0.310; P=0.337; IDI, 0.005; 95% CI, −0.005 to 0.015; P=0.337).

Conclusions

In suspected or known CHD patients with CKD undergoing elective coronary angiography, elevated VEGF-D levels may predict all-cause mortality independent of established risk factors and cardiovascular biomarkers.

Acknowledgement/Funding

The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization

P3765Low vascular endothelial growth factor-C was a predictor for cardiovascular events in patients with atrial fibrillation and suspected or known coronary artery disease: a subanalysis of the ANOX study

Background

Lymphatic system has been considered to play an important role in cardiovascular disease. We recently reported that vascular endothelial growth factor-C (VEGF-C), a central player in lymphangiogenesis, predicted all-cause mortality in patients with suspected or known coronary artery disease (CAD). However, relationship between VEGF-C and atrial fibrillation (AF) remains unclear.

Methods

The ANOX study is a multicenter, prospective cohort study of 2,418 patients with suspected CAD, to determine the predictive value of possible novel biomarkers related to angiogenesis or oxidative stress for major adverse cardiovascular events (MACE) among patients undergoing elective angiography. Blood samples were collected from the arterial catheter sheath at the beginning of coronary angiography. Serum levels of VEGF-C, as well as N-terminal pro-brain natriuretic peptide (NT-proBNP), high-sensitivity troponin-I (cTnI), and high-sensitivity C-reactive protein (hsCRP), were measured. The outcome was a MACE defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke.

Results

Of a total of 2,418 patients, 261 patients had AF at baseline. AF group were older, and had more chronic kidney disease, history of heart failure, and history of stroke, but less diabetes, dyslipidemia, and CAD. The median level of NT-proBNP, cTnI, and hsCRP were higher in AF group [AF vs non-AF: NT-proBNP, 1048 pg/ml vs 162 pg/ml (p<0.0001); cTnI, 0.0003 ng/ml, vs 0.0 ng/ml (p<0.0001); hsCRP, 1.43 ug/ml vs 0.88 ug/ml (p=0.0005)], whereas median level of VEGF-C was lower in AF group [3107 pg/ml vs 3590 pg/ml (p<0.0001)]. AF was associated with lower VEGF-C and higher hsCRP after adjustment for potential confounders. During the 3-year follow-up, 29 (11.1%) patients in AF group and 136 (6.3%) patients in non-AF group developed MACE (p=0.007). Incidence of stroke was higher in AF group (17 (6.5%) vs 52 (2.4%); p<0.0009), despite that the incidence of cardiovascular death and myocardial infarction were similar between the groups. We divided the entire cohort into two groups based on the lowest quartile of VEGF-C or highest quartile of other biomarkers, lowest quartile of VEGF-C (log rank p=0.0004), as well as highest quartile of cTnI (log rank p=0.0009), were significantly associated with MACE in AF group. After adjustment for established risk factors and these biomarkers, both lowest quartile of VEGF-C (HR, 2.73; 95% CI, 1.27–6.06) and highest quartile of cTnI (HR, 2.54; 95% CI, 1.08–6.09) were significantly associated with MACE in AF group.

Conclusions

AF was associated with lower level of VEGF-C, and low VEGF-C as well as high cTnI might serve as an independent predictor of MACE in patients with AF and suspected or known CAD.

P3635Vascular endothelial growth factor-D and mortality in patients with suspected but no history of coronary heart disease: a subanalysis of the ANOX study

Background

Vascular endothelial growth factor-D (VEGF-D) is a secreted glycoprotein that can act as lymphangiogenic and angiogenic growth factors through binding to its specific receptors, VEGFR-3 (Flt-4) and VEGFR-2 (KDR/Flk-1). VEGF-D signaling via VEGFR-3 plays an important role in lipoprotein metabolisms which may contribute to coronary heart disease (CHD). VEGF-D signaling has been used as a therapeutic target of human diseases such as lymphangioleiomyomatosis and refractory angina. In clinical settings, the VEGF-D level is already established as a diagnostic biomarker for lymphangioleiomyomatosis. However, the prognostic value of VEGF-D in patients with suspected but no history of CHD is unknown.

Methods

Serum VEGF-D levels were measured in 1,717 patients with suspected but no history of CHD undergoing elective coronary angiography, enrolled in the development of novel biomarkers related to angiogenesis or oxidative stress to predict cardiovascular events (ANOX) study, and followed up for 3 years. The primary outcome was all-cause death. The secondary outcomes were cardiovascular death, and major adverse cardiovascular events (MACE) defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal stroke.

Results

During the follow-up, 161 patients died from any cause, 50 died from cardiovascular disease, and 104 developed MACE. After adjustment for established risk factors, VEGF-D levels were significantly associated with all-cause death (hazard ratio [HR] for 1-SD increase, 1.29; 95% confidence interval [CI], 1.17–1.42), cardiovascular death (HR, 1.37; 95% CI, 1.20–1.56), and MACE (HR, 1.22; 95% CI, 1.08–1.37). Even after incorporation of N-terminal pro-brain natriuretic peptide, contemporary sensitive cardiac troponin-I, and high-sensitivity C-reactive protein into a model with established risk factors, the addition of VEGF-D levels further improved the prediction of all-cause death (continuous net reclassification improvement [NRI], 0.165; 95% CI, 0.004–0.325; P=0.044; integrated discrimination improvement [IDI], 0.012; 95% CI, 0.002–0.023; P=0.013), but not that of cardiovascular death (NRI, 0.078; 95% CI, r=−0.203–0.359; P=0.586; IDI, 0.014; 95% CI, r=−0.009–0.037; P=0.235) or MACE (NRI, r=−0.011; 95% CI, r=−0.207–0.184; P=0.337; IDI, 0.003; 95% CI, r=−0.003–0.009; P=0.354).

Conclusions

In patients with suspected but no history of CHD undergoing elective coronary angiography, elevated VEGF-D levels may predict all-cause mortality independent of established risk factors and cardiovascular biomarkers.

Acknowledgement/Funding

The ANOX study is supported by a Grant-in-Aid for Clinical Research from the National Hospital Organization.

Hole-phonon coupling effect on the band dispersion of organic molecular semiconductors

The dynamic interaction between the traveling charges and the molecular vibrations is critical for the charge transport in organic semiconductors. However, a direct evidence of the expected impact of the charge-phonon coupling on the band dispersion of organic semiconductors is yet to be provided. Here, we report on the electronic properties of rubrene single crystal as investigated by angle resolved ultraviolet photoelectron spectroscopy. A gap opening and kink-like features in the rubrene electronic band dispersion are observed. In particular, the latter results in a large enhancement of the hole effective mass (> 1.4), well above the limit of the theoretical estimations. The results are consistent with the expected modifications of the band structures in organic semiconductors as introduced by hole-phonon coupling effects and represent an important experimental step toward the understanding of the charge localization phenomena in organic materials.The charge transport properties in organic semiconductors are affected by the impact of molecular vibrations, yet it has been challenging to quantify them to date. Here, Bussolotti et al. provide direct experimental evidence on the band dispersion modified by molecular vibrations in a rubrene single crystal.

Association of CAD, a multifunctional protein involved in pyrimidine synthesis, with mLST8, a component of the mTOR complexes

Background

mTOR is a genetically conserved serine/threonine protein kinase, which controls cell growth, proliferation, and survival. A multifunctional protein CAD, catalyzing the initial three steps in de novo pyrimidine synthesis, is regulated by the phosphorylation reaction with different protein kinases, but the relationship with mTOR protein kinase has not been known.

Results

CAD was recovered as a binding protein with mLST8, a component of the mTOR complexes, from HEK293 cells transfected with the FLAG-mLST8 vector. Association of these two proteins was confirmed by the co-immuoprecipitaiton followed by immunoblot analysis of transfected myc-CAD and FLAG-mLST8 as well as that of the endogenous proteins in the cells. Analysis using mutant constructs suggested that CAD has more than one region for the binding with mLST8, and that mLST8 recognizes CAD and mTOR in distinct ways. The CAD enzymatic activity decreased in the cells depleted of amino acids and serum, in which the mTOR activity is suppressed.

Conclusion

The results obtained indicate that mLST8 bridges between CAD and mTOR, and plays a role in the signaling mechanism where CAD is regulated in the mTOR pathway through the association with mLST8.

Meloxicam, a COX-2 inhibitor, ameliorates ischemia/reperfusion injury in non-heart-beating donor livers

BACKGROUND/AIMS

Chronic organ donor shortage has led to the consideration to expand the donor pool with livers from non-heart-beating donors (NHBD), although a higher risk of graft dys- or nonfunction is associated with these livers. We examined the effects of selective cyclooxygenase-2 (COX-2) inhibition on hepatic warm ischemia (WI) reperfusion (I/R) injury of NHBD.

METHODS

Male Wistar rats were used as donors and meloxicam (5 mg/kg body weight) was administered into the preservation solution. Livers were excised after 60 min of WI in situ, flushed and preserved for 24 h at 4°C. Reperfusion was carried out in vitro at a constant flow for 45 min. During reperfusion (5, 15, 30 and 45 min), enzyme release of alanine aminotransferase and glutamate lactate dehydrogenase were measured as well as portal venous pressure, bile production and oxygen consumption. The production of malondialdehyde was quantified and TUNEL staining was performed. Quantitative PCR analyzed COX-2 mRNA. COX-2 immunohistochemistry and TxB(2) detection completed the measurements.

RESULTS

Meloxicam treatment led to better functional recovery concerning liver enzyme release, vascular resistance and metabolic activity over time in all animals. Oxidative stress and apoptosis were considerably reduced.

CONCLUSION

Cold storage using meloxicam resulted in significantly better integrity and function of livers retrieved from NHBD. Selective COX-2 inhibition is a new therapeutic approach achieving improved preservation of grafts from NHBD.

Association between the neutrophil myeloperoxidase index and subsets of bacterial infections

The mean myeloperoxidase index (MPXI) is calculated during the routine complete blood count performed using the autoanalyzer ADVIA120/2120. The pattern of changes in the neutrophil myeloperoxidase levels in patients with specific infectious diseases was analyzed by assessing the MPXI levels. In patients with bacterial sepsis, identified by positive blood-culture tests, with (n = 29) and without (n = 51) systemic inflammatory response syndrome, the mean MPXI significantly reduced to -3.18 and -2.06, respectively. In contrast, among patients with nontuberculous nonseptic bacterial infections (n = 40), the mean MPXI significantly elevated to 5.51, while tuberculosis patients (n = 37) and patients with viral infection (n = 60) showed an unchanged MPXI (mean values, -0.46 and -1.06, respectively). Among the parameters of inflammation, only the C-reactive protein values showed a weak correlation with the MPXI levels. [Conclusion] These results indicate that MPXI is correlated with some specific infectious states, i.e. MPXI is low in bacterial sepsis and high in nontuberculous nonseptic bacterial infections. MPXI appears to be an independent and useful biomarker for the diagnosis and follow-up of infectious diseases, especially when the MPXI values are obtained at regular intervals during the disease courses of the patients.

Tti1 and Tel2 are critical factors in mammalian target of rapamycin complex assembly

Mammalian target of rapamycin (mTOR) is a member of the phosphatidylinositol 3-kinase-related kinase (PIKK) family and is a major regulator of translation, cell growth, and autophagy. mTOR exists in two distinct complexes, mTORC1 and mTORC2, that differ in their subunit composition. In this study, we identified KIAA0406 as a novel mTOR-interacting protein. Because it has sequence homology with Schizosaccharomyces pombe Tti1, we named it mammalian Tti1. Tti1 constitutively interacts with mTOR in both mTORC1 and mTORC2. Knockdown of Tti1 suppresses phosphorylation of both mTORC1 substrates (S6K1 and 4E-BP1) and an mTORC2 substrate (Akt) and also induces autophagy. S. pombe Tti1 binds to Tel2, a protein whose mammalian homolog was recently reported to regulate the stability of PIKKs. We confirmed that Tti1 binds to Tel2 also in mammalian cells, and Tti1 interacts with and stabilizes all six members of the PIKK family of proteins (mTOR, ATM, ATR, DNA-PKcs, SMG-1, and TRRAP). Furthermore, using immunoprecipitation and size-exclusion chromatography analyses, we found that knockdown of either Tti1 or Tel2 causes disassembly of mTORC1 and mTORC2. These results indicate that Tti1 and Tel2 are important not only for mTOR stability but also for assembly of the mTOR complexes to maintain their activities.

Exogenous superoxide dismutase prevents peroxynitrite-induced apoptosis in non-heart-beating donor livers

OBJECTIVE

To investigate the role of oxygen free radicals in the induction of apoptosis in non-heart-beating donor (NHBD) livers, and if superoxide dismutase (SOD) ameliorates these alterations.

METHODS

Rat livers were perfused via the portal vein with histidine/tryptophan/alpha-ketoglutarate solution from heart-beating donors (HBD) or 60-min warm ischemia from NHBD, with or without the addition of SOD. After 24 h, cold storage livers were evaluated by isolated reperfusion.

RESULTS

NHBD showed significantly higher enzyme leakage and elevated portal venous pressure (PVP) versus HBD. Bile and total adenine nucleotides (TAN) were significantly decreased. Apoptosis was prominent in sinusoidal lining cells, coupled with strong nitrotyrosine staining (NTR). The concentrations of nitric oxide and lipoperoxides were largely increased. SOD medication reduced hepatic enzyme release by 30% and lipoperoxides by nearly 50%. Apoptosis and NTR were significantly decreased, and PVP was strikingly reduced to normal values. A 3-fold enhancement in bile production and 1.5-fold increase in TAN of the liver tissue were also observed.

CONCLUSION

NHBD livers are prone to severe reoxygenation injury promoted by oxygen free radicals, massive nitrite oxide production and peroxynitrite-induced apoptosis within the sinusoids. Antioxidant medication with SOD should be considered as a useful means of preserving NHBD livers.

Regulation of hypoxia-inducible factor 1 by glucose availability under hypoxic conditions

Hypoxia-inducible transcription factor 1 (HIF-1), consisting of HIF-1 alpha and HIF-1 beta subunits, regulates the expression of a variety of genes involved in diverse adaptive processes in response to hypoxia. While oxygen availability regulates HIF-1 alpha by proteolytic degradation, some growth factors regulate HIF-1 alpha by protein synthesis in part through mammalian target of rapamycin complex 1 (TORC1) pathway. We herein report the role of nutrient availability on the regulation of HIF-1. A reduced availability of glucose, not amino acids, results in a decrease of the expression of HIF1-dependent genes and HIF-1 alpha protein in response to hypoxia. HIF-1 alpha mRNA expression was not significantly suppressed and DMOG, an inhibitor for proteasomal degradation of HIF-1 alpha, did not induce HIF-1 alpha protein expression under hypoxia combined with glucose depletion. In comparison to the effect in the presence of glucose, glucose depletion under hypoxia induced a much stronger activation of the AMP-dependent kinase pathway and phosphorylation of eIF2 alpha, and nearly complete inhibition of the TORC1 pathway. These findings imply that the reduced availability of glucose under hypoxia downregulates HIF-1 in part through the inhibition of HIF-1 alpha mRNA translation, which is occasionally observed in pathophysiological situations such as ischemic diseases.

AMP-activated protein kinase phosphorylates glutamine : fructose-6-phosphate amidotransferase 1 at Ser243 to modulate its enzymatic activity

Glutamine : fructose-6-phosphate amidotransferase 1 (GFAT1) was identified as a protein phosphorylated in glucose-deprived cells by immunoprecipitation using the anti-phospho Akt substrates (PAS) antibody, which recognizes the phosphorylation motif site by AMP-activated protein kinase (AMPK), followed by mass fingerprinting analysis. Glucose depletion-induced phosphorylation of endogenous GFAT was potentiated by 2-deoxyglucose (2-DG), an AMPK activator, and the 2-DG-stimulated phosphorylation of FLAG-tagged GFAT1 in transfected cells was suppressed by Compound C, an AMPK inhibitor. The 2-DG induced phosphorylation of GFAT1 was attenuated by the introduction of the kinase-negative mutant of AMPK, and the phosphorylation was observed in the cells expressing the constitutively active mutant of AMPK even in the absence of 2-DG. Subsequent analysis revealed that the PAS antibody recognized GFAT1 phosphorylated at Ser243, which is conserved among different species. The assay of the GFAT enzymatic activity in the cell lysates indicated that the 2-DG-treatment inhibited the enzymatic activity, and Compound C-preincubation partially prevented the 2-DG-induced decrease of the activity. Furthermore, the mutant replacing Ser243 by alanine partially prevented the decrease of GFAT activity by 2-DG treatment. These results indicate that the phosphorylation of GFAT1 at Ser243 by AMPK has an important role in the regulation of the GFAT1 enzymatic activity.

AMP-activated protein kinase phosphorylates Golgi-specific brefeldin A resistance factor 1 at Thr1337 to induce disassembly of Golgi apparatus

Sufficiency and depletion of nutrients regulate the cellular activities through the protein phosphorylation reaction; however, many protein substrates remain to be clarified. GBF1 (Golgi-specific brefeldin A resistance factor 1), a guanine nucleotide exchange factor for the ADP-ribosylation factor family associated with the Golgi apparatus, was isolated as a phosphoprotein from the glucose-depleted cells by using the phospho-Akt-substrate antibody, which recognizes the substrate proteins of several protein kinases. The phosphorylation of GBF1 was induced by 2-deoxyglucose (2-DG), which blocks glucose utilization and increases the intracellular AMP concentration, and by AICAR, an AMP-activated protein kinase (AMPK) activator. This phosphorylation was observed in the cells expressing the constitutively active AMPK. The 2-DG-induced phosphorylation of GBF1 was suppressed by Compound C, an AMPK inhibitor, and by the overexpression of the kinase-negative AMPK. Analysis using the deletion and point mutants identified Thr(1337) as the 2-DG-induced phosphorylation site in GBF1, which is phosphorylated by AMPK in vitro. ATP depletion is known to provoke the Golgi apparatus disassembly. Immunofluorescent microscopic analysis with the Golgi markers indicated that GBF1 associates with the fragmented Golgi apparatus in the cells treated with 2-DG and AICAR. The expression of the kinase-negative AMPK and the GBF1 mutant replacing Thr(1337) by Ala prevented the 2-DG-induced Golgi disassembly. These results indicate that GBF1 is a novel AMPK substrate and that the AMPK-mediated phosphorylation of GBF1 at Thr(1337) has a critical role, presumably by attenuating the function of GBF1, in the disassembly of the Golgi apparatus induced under stress conditions that lower the intracellular ATP concentration.

Identification of TBC7 having TBC domain as a novel binding protein to TSC1-TSC2 complex

TBC7, a TBC (Tre-2/Bub2/Cdc16) 1 domain protein, was identified as a novel binding protein to the TSC1-TSC2 tumor suppressor complex by peptide mass fingerprinting analysis of the proteins immunoprecipitated with FLAG-epitope tagged TSC1 and TSC2 from the transfected mammalian cells. The in vivo and in vitro association of TBC7 and the TSC1-TSC2 complex was confirmed by the co-immunoprecipitation and pull-down analysis, respectively, and TBC7 was revealed to bind to the C-terminal half region of TSC1, which is distinct from the binding site with TSC2. The immunofluorescence microscopy and subcellular fractionation showed that TBC7 co-localizes with the tumor suppressor complex in the endomembrane. Overexpression of TBC7 enhanced ubiquitination of TSC1 and increased phosphorylation of S6 protein by S6 kinase, that is located in the mTOR-signaling pathway. These results indicate TBC7 could take a part in the negative regulation of the tumor suppressor complex through facilitating the downregulation of TSC1.

The proline-rich Akt substrate of 40 kDa (PRAS40) is a physiological substrate of mammalian target of rapamycin complex 1

The proline-rich Akt substrate of 40 kilodaltons (PRAS40) was identified as a raptor-binding protein that is phosphorylated directly by mammalian target of rapamycin (mTOR) complex 1 (mTORC1) but not mTORC2 in vitro, predominantly at PRAS40 (Ser(183)). The binding of S6K1 and 4E-BP1 to raptor requires a TOR signaling (TOS) motif, which contains an essential Phe followed by four alternating acidic and small hydrophobic amino acids. PRAS40 binding to raptor was severely inhibited by mutation of PRAS40 (Phe(129) to Ala). Immediately carboxyl-terminal to Phe(129) are two small hydrophobic amino acid followed by two acidic residues. PRAS40 binding to raptor was also abolished by mutation of the major mTORC1 phosphorylation site, Ser(183), to Asp. PRAS40 (Ser(183)) was phosphorylated in intact cells; this phosphorylation was inhibited by rapamycin, by 2-deoxyglucose, and by overexpression of the tuberous sclerosis complex heterodimer. PRAS40 (Ser(183)) phosphorylation was also inhibited reversibly by withdrawal of all or of only the branched chain amino acids; this inhibition was reversed by overexpression of the Rheb GTPase. Overexpressed PRAS40 suppressed the phosphorylation of S6K1 and 4E-BP1 at their rapamycin-sensitive phosphorylation sites, and reciprocally, overexpression of S6K1 or 4E-BP1 suppressed phosphorylation of PRAS40 (Ser(183)) and its binding to raptor. RNA interference-induced depletion of PRAS40 enhanced the amino acid-stimulated phosphorylation of both S6K1 and 4E-BP1. These results establish PRAS40 as a physiological mTORC1 substrate that contains a variant TOS motif. Moreover, they indicate that the ability of raptor to bind endogenous substrates is limiting for the activity of mTORC1 in vivo and is therefore a potential locus of regulation.

Suppression of the mTOR-raptor signaling pathway by the inhibitor of heat shock protein 90 geldanamycin

Heat shock protein 90 (Hsp90) was co-immunoprecipitated with raptor, the binding partner of the mammalian target of rapamycin (mTOR) from HEK293 cells. Hsp90 was detected in the anti-raptor antibody immunoprecipitates prepared from the cell extract by immunoblot analysis using the anti-Hsp90 antibody, and the association of these two proteins was confirmed by immunoprecipitation from the cells co-expressing Hsp90 and raptor as epitope-tagged molecules. Geldanamycin, a potent inhibitor of Hsp90, disrupted the in vivo binding of Hsp90 to raptor without affecting the association of raptor and mTOR, and suppressed the phosphorylation by mTOR of the downstream translational regulators p70 S6 kinase (S6K) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). The protein kinase activity of S6K as well as the phosphorylation of the substrate, 40S ribosomal protein S6, were lowered in the geldanamycin-treated cells. These results indicate that Hsp90 is involved in the regulation of protein translation by facilitating the phosphorylation reaction of 4E-BP1 and S6K catalyzed by the mTOR/raptor complex through the association with raptor, and that the mTOR signaling pathway is a novel target of geldanamycin.

Insulin and amino-acid regulation of mTOR signaling and kinase activity through the Rheb GTPase

Target of Rapamycin (TOR), a giant protein kinase expressed by all eucaryotic cells, controls cell size in response to nutrient signals. In metazoans, cell and organismal growth is controlled by nutrients and the insulin/insulin-like growth factor (IGF) system, and the understanding of how these inputs coordinately regulate TOR signaling has advanced greatly in the past 5 years. In single-cell eucaryotes and Caenorhabditis elegans, TOR is a dominant regulator of overall mRNA translation, whereas in higher metazoans, TOR controls the expression of a smaller fraction of mRNAs that is especially important to cell growth. TOR signals through two physically distinct multiprotein complexes, and the control of cell growth is mediated primarily by TOR complex 1 (TORC1), which contains the polypeptides raptor and LST8. Raptor is the substrate binding element of TORC1, and the ability of raptor to properly present substrates, such as the translational regulators 4E-BP and p70 S6 kinase, to the TOR catalytic domain is essential for their TOR-catalysed phosphorylation, and is inhibited by the Rapamycin/FKBP-12 complex. The dominant proximal regulator of TORC1 signaling and kinase activity is the ras-like small GTPase Rheb. Rheb binds directly to the mTOR catalytic domain, and Rheb-GTP enables TORC1 to attain an active configuration. Insulin/IGF enhances Rheb GTP charging through the ability of activated Akt to inhibit the Rheb-GTPase-activating function of the tuberous sclerosis heterodimer (TSC1/TSC2). Conversely, energy depletion reduces Rheb-GTP charging through the ability of the adenosine monophosphate-activated protein kinase to phosphorylate TSC2 and stimulate its Rheb-GTPase activating function, as well as by HIFalpha-mediated transcriptional responses that act upstream of the TSC1/2 complex. Amino-acid depletion inhibits TORC1 acting predominantly downstream of the TSC complex, by interfering with the ability of Rheb to bind to mTOR. The components of the insulin/IGF pathway to TORC1 are now well established, whereas the elements mediating the more ancient and functionally dominant input of amino acids remain largely unknown.

Nutrient-dependent Multimerization of the Mammalian Target of Rapamycin through the N-terminal HEAT Repeat Region

The mammalian target of rapamycin (mTOR) plays a pivotal role in the regulation of cell growth in response to a variety of signals such as nutrients and growth factors. mTOR forms two distinct complexes in vivo. mTORC1 (mTOR complex 1) is rapamycin-sensitive and regulates the rate of protein synthesis in part by phosphorylating two well established effectors, S6K1 (p70 ribosomal S6 kinase 1) and 4E-BP1 (eukaryotic initiation factor 4E-binding protein 1). mTORC2 is rapamycin-insensitive and likely regulates actin organization and activates Akt/protein kinase B. Here, we show that mTOR forms a multimer via its N-terminal HEAT repeat region in mammalian cells. mTOR multimerization is promoted by amino acid sufficiency, although the state of multimerization does not directly correlate with the phosphorylation state of S6K1. mTOR multimerization was insensitive to rapamycin treatment but hindered by butanol treatment, which inhibits phosphatidic acid production by phospholipase D. We also found that mTOR forms a multimer in both mTORC1 and mTORC2. In addition, Saccharomyces cerevisiae TOR proteins Tor1p and Tor2p also exist as homomultimers. These results suggest that TOR multimerization is a conserved mechanism for TOR functioning.

TOR regulates late steps of ribosome maturation in the nucleoplasm via Nog1 in response to nutrients

The protein kinase TOR (target of rapamycin) controls several steps of ribosome biogenesis, including gene expression of rRNA and ribosomal proteins, and processing of the 35S rRNA precursor, in the budding yeast Saccharomyces cerevisiae. Here we show that TOR also regulates late stages of ribosome maturation in the nucleoplasm via the nuclear GTP-binding protein Nog1. Nog1 formed a complex that included 60S ribosomal proteins and pre-ribosomal proteins Nop7 and Rlp24. The Nog1 complex shuttled between the nucleolus and the nucleoplasm for ribosome biogenesis, but it was tethered to the nucleolus by both nutrient depletion and TOR inactivation, causing cessation of the late stages of ribosome biogenesis. Furthermore, after this, Nog1 and Nop7 proteins were lost, leading to complete cessation of ribosome maturation. Thus, the Nog1 complex is a critical regulator of ribosome biogenesis mediated by TOR. This is the first description of a physiological regulation of nucleolus-to-nucleoplasm translocation of pre-ribosome complexes.

Phosphorylation and Up-regulation of Diacylglycerol Kinase γ via Its Interaction with Protein Kinase Cγ

Diacylglycerol (DAG) acts as an allosteric activator of protein kinase C (PKC) and is converted to phosphatidic acid by DAG kinase (DGK). Therefore, DGK is thought to be a negative regulator of PKC activation. Here we show molecular mechanisms of functional coupling of the two kinases. gammaPKC directly associated with DGKgamma through its accessory domain (AD), depending on Ca2+ as well as phosphatidylserine/diolein in vitro. Mass spectrometric analysis and mutation studies revealed that gammaPKC phosphorylated Ser-776 and Ser-779 in the AD of DGKgamma. The phosphorylation by gammaPKC resulted in activation of DGKgamma because a DGKgamma mutant in which Ser-776 and Ser-779 were substituted with glutamic acid to mimic phosphorylation exhibited significantly higher activity compared with wild type DGKgamma and an unphosphorylatable DGKgamma mutant. Importantly, the interaction of the two kinases and the phosphorylation of DGKgamma by gammaPKC could be confirmed in vivo, and overexpression of the AD of DGKgamma inhibited re-translocation of gammaPKC. These results demonstrate that localization and activation of the functionally correlated kinases, gammaPKC and DGKgamma, are spatio-temporally orchestrated by their direct association and phosphorylation, contributing to subtype-specific regulation of DGKgamma and DAG signaling.

Different roles for the TOS and RAIP motifs of the translational regulator protein 4E-BP1 in the association with raptor and phosphorylation by mTOR in the regulation of cell size

The translational regulator protein 4E-BP1, that binds to eukaryotic initiation factor-4E (eIF4E) to prevent the formation of the active translation complex, dissociates from eIF4E by phosphorylation through the mammalian target of rapamycin (mTOR) in the cells stimulated by amino acids. 4E-BP1 has been shown to associate with the scaffold protein raptor through its TOS and RAIP motifs to be recognized by mTOR. We revealed that the TOS motif mutant was phosphorylated by mTOR only at the priming sites of Thr37/46 but the RAIP motif mutant was phosphorylated not only at the priming sites but also at the subsequent site of Thr70 in vitro and in response to amino acid treatment in HEK293 cells. Analysis using the phosphorylation site mutants indicated that phosphorylation of the priming and subsequent sites of 4E-BP1 was required for dissociation from raptor as well as for the release of eIF4E. The expression of the 4E-BP1 mutants replacing the TOS motif and phosphorylation sites, that are poor substrates for mTOR and have no or little dissociation ability from raptor and eIF4E, respectively, significantly reduced the size of K562 cells. These results indicate that the the TOS motif has an essential function whereas the RAIP motif has an accessory role in the association with raptor and mTOR-mediated phosphorylation of 4E-BP1 to dissociate it from raptor and release eIF4E in response to amino acid stimulation leading to the control of cell size.