Deciphering metabolic dysfunction-associated steatotic liver disease: insights from predictive modeling and clustering analysis.

BACKGROUND AND AIM: New nomenclature of steatotic liver disease (SLD) including metabolic dysfunction-associated SLD (MASLD), MASLD and increased alcohol intake (MetALD), and alcohol-associated liver disease (ALD) has recently been proposed. We investigated clustering analyses to decipher the complex landscape of SLD pathologies including the former nomenclature of nonalcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated fatty liver disease (MAFLD). METHODS: Japanese individuals who received annual health checkups including abdominal ultrasonography (n = 15 788, men/women: 10 250/5538, mean age: 49 years) were recruited. RESULTS: The numbers of individuals with SLD, MASLD, MetALD, ALD, NAFLD, and MAFLD were 5603 (35.5%), 4227 (26.8%), 795 (5.0%), 324 (2.1%), 3982 (25.8%), and 4946 (31.3%), respectively. Clustering analyses using t-distributed stochastic neighbor embedding and K-means to visually represent interconnections in SLDs uncovered five cluster formations. MASLD and NAFLD mainly shared three clusters including (i) low alcohol intake with relatively low-grade obesity; (ii) obesity with dyslipidemia; and (iii) dysfunction of glucose metabolism. Both MetALD and ALD displayed one distinct cluster intertwined with alcohol consumption. MAFLD widely shared all of the five clusters. In machine learning-based analyses using algorithms of random forest and extreme gradient boosting and receiver operating characteristic curve analyses, fatty liver index (FLI), calculated by body mass index, waist circumference, and levels of γ-glutamyl transferase and triglycerides, was selected as a useful feature for SLDs. CONCLUSIONS: The new nomenclature of SLDs is useful for obtaining a better understanding of liver pathologies and for providing valuable insights into predictive factors and the dynamic interplay of diseases. FLI may be a noninvasive predictive marker for detection of SLDs.

Metabolic dysfunction-associated fatty liver disease predicts new onset of chronic kidney disease better than fatty liver or nonalcoholic fatty liver disease.

BACKGROUND: Possible associations of chronic kidney disease (CKD) with fatty liver (FL) and nonalcoholic fatty liver disease (NAFLD) have recently been focused on. Metabolic dysfunction-associated fatty liver disease (MAFLD), defined as FL with overweight/obesity, type 2 diabetes mellitus or metabolic abnormalities, has been proposed as a new feature of chronic liver disease. However, the relationship between MAFLD and new onset of CKD has not been fully addressed. METHODS: We investigated the associations of FL, NAFLD and MAFLD with the development of CKD, defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 or positive for urinary protein, over a 10-year period in 28 890 Japanese subjects who received annual health examinations. After exclusion of subjects with no data for abdominal ultrasonography and subjects with CKD at baseline, a total of 13 159 subjects (men 8581, women 4578; mean age 48 years) were recruited. RESULTS: The prevalence of FL, NAFLD and MAFLD was 34.6% (men 45.1%, women 15.1%), 32.8% (men 42.7%, women 14.5%) and 32.3% (men 42.4%, women 13.4%), respectively. During the 10-year follow-up period, 2163 subjects (men 1475, women 688) had new onset of CKD. Multivariable Cox proportional hazards model analyses showed that MAFLD [hazard ratio 1.12 (95% confidence interval 1.02-1.26); P = .027] but not FL or NAFLD was an independent risk factor for new onset of CKD after adjustment of age, sex, eGFR, current smoking habit, ischemic heart disease, diabetes mellitus, overweight/obesity, hypertension and dyslipidemia. The addition of MAFLD [continuous net reclassification improvement (NRI) 0.154, integrated discrimination improvement (IDI) 0.0024] to traditional risk factors without metabolic abnormalities significantly improved the discriminatory capacity better than did the addition of FL (NRI 0.138, IDI 0.0018) or NAFLD (NRI 0.132, IDI 0.0017). CONCLUSIONS: MAFLD is modestly and independently associated with new onset of CKD and predicts the risk for development of CKD better than FL or NAFLD.

Comparison of Phenotypes in Subcutaneous Fat and Perivascular Adipose Tissue Surrounding the Saphenous Vein in Coronary Artery Bypass Grafting.

BACKGROUND: The saphenous vein (SV) is used as an essential conduit in coronary artery bypass grafting (CABG), but the long-term patency of SV grafts is a crucial issue. The use of the novel "no-touch" technique of harvesting the SV together with its surrounding tissue has been reported to result in good long-term graft patency of SV grafts. We recently showed that perivascular adipose tissue (PVAT) surrounding the SV (SV-PVAT) had lower levels of metaflammation and consecutive adipose tissue remodeling than did PVAT surrounding the coronary artery. However, the difference between SV-PVAT and subcutaneous adipose tissue (SCAT) remains unclear.Methods and Results: Fat pads were sampled from 55 patients (38 men, 17 women; mean [±SD] age 71±8 years) with coronary artery disease who underwent elective CABG. Adipocyte size was significantly larger in SV-PVAT than SCAT. The extent of fibrosis was smaller in SV-PVAT than SCAT. There were no significant differences between SCAT and SV-PVAT in macrophage infiltration area, quantified by antibodies for CD68, CD11c, and CD206, or in gene expression levels of metaflammation-related markers. Expression patterns of adipocyte developmental and pattern-forming genes differed between SCAT and SV-PVAT. CONCLUSIONS: The properties of SV-PVAT are close to, but not the same as, those of SCAT, possibly resulting from inherent differences in adipocytes. SV-PVAT has healthy expansion with less fibrosis in fat than SCAT.

Diabetes modulation of the myocardial infarction-acute kidney injury axis.

As there is cross talk in functions of the heart and kidney, acute or chronic injury in one of the two organs provokes adaptive and/or maladaptive responses in both organs, leading to cardiorenal syndrome (CRS). Acute kidney injury (AKI) induced by acute heart failure is referred to as type 1 CRS, and a frequent cause of this type of CRS is acute myocardial infarction (AMI). Diabetes mellitus increases the risk of AMI and also the risk of AKI of various causes. However, there have been only a few studies in which animal models of diabetes were used to examine how diabetes modulates AMI-induced AKI. In this review, we summarize findings regarding the mechanisms of type 1 CRS and the impact of diabetes on both AMI and renal susceptibility to AKI and we discuss mechanisms by which diabetes modulates AMI-induced AKI. Hemodynamic alterations induced by AMI could be augmented by diabetes via its detrimental effect on infarct size and contractile function of the noninfarcted region in the heart. Diabetes increases susceptibility of renal cells to hypoxia and oxidative stress by modulation of signaling pathways that regulate cell survival and autophagy. Recent studies have shown that diabetes mellitus even at early stage of cardiomyopathy/nephropathy predisposes the kidney to AMI-induced AKI, in which activation of Toll-like receptors and reactive oxygen species derived from NADPH oxidases are involved. Further analysis of cross talk between diabetic cardiomyopathy and diabetic kidney disease is necessary for obtaining a more comprehensive understanding of modulation of the AMI-AKI axis by diabetes.

High fatty liver index is an independent predictor of ischemic heart disease during a 10-year period in a Japanese population.

AIM: Fatty liver index (FLI), which is calculated by using body mass index, waist circumference and levels of γ-glutamyl transferase and triglycerides, is a validated surrogate marker of nonalcoholic fatty liver disease. We retrospectively investigated the relationship between FLI and the development of ischemic heart disease (IHD) during a 10-year period. METHODS: Among subjects who received annual health checkups (n = 28 990), a total of 18 851 subjects (men/women: 11 659/7192) were enrolled after exclusion of subjects with missing data and those with IHD at baseline. RESULTS: FLI at baseline was significantly higher in men than in women. During the 10-year period, 450 men (3.9%) and 123 women (1.7%) had new onset of IHD determined by a self-reported questionnaire survey. Multivariable Cox proportional hazard models with a restricted cubic spline showed that hazard risk (HR) for the development of IHD increased with a higher FLI at baseline after adjustment of age, sex, current smoking habit, family history of IHD and diagnosis of diabetes mellitus, hypertension, dyslipidemia and chronic kidney disease at baseline. There was no significant interaction between FLI and sex for the adjusted HR. When divided by tertiles of FLI at baseline (T1∼T3), the adjusted risk for development of IHD in the T3 group (HR [95% confidence interval]: 1.34 [1.05-1.71]) was significantly higher than that in the T1 group as the reference. The addition of FLI into traditional risk factors for IHD significantly improved the discriminatory capability. CONCLUSIONS: A high level of FLI is an independent predictor of new onset of IHD during a 10-year period.

Clinical and pathological characteristics of patients with acute kidney injury in Japan in whom kidney biopsy was performed: a cross-sectional analysis of the Japan Renal Biopsy Registry (J­RBR).

INTRODUCTION: Acute kidney injury (AKI) is a worldwide concern and it leads to a poor prognosis or end-stage kidney disease. The purpose of this study was to clarify the characteristics of patients with AKI in whom kidney biopsy was performed using data of the Japan Renal Biopsy Registry (J-RBR). METHODS: We screened 38,351 cases that were registered in the J-RBR from 2007 to 2018. We obtained data for 383 patients with AKI based on clinical diagnosis for analysis 1 and data for 714 patients with acute interstitial nephritis (AIN) or acute tubular necrosis (ATN) based on pathological diagnosis for analysis 2. RESULTS: Of the cases screened, 383 patients with AKI (1.0%) were included in analysis 1. The main pathological diagnoses of AKI were AIN, ATN, chronic interstitial nephritis, nephro-sclerosis and crescentic glomerulonephritis. Of the cases screened, 589 patients with AIN (1.5%) and 110 patients with ATN (0.3%) were included in analysis 2. The main clinical diagnoses of AIN were AKI, rapidly progressive glomerulonephritis (RPGN), chronic nephritic syndrome (CNS) and drug-induced nephropathy (DIN), whereas those of ATN were AKI, RPGN, DIN and CNS. ATN patients had a higher serum creatinine level than that of AIN patients. CONCLUSION: Our results revealed that cases in the J-RBR included 1.0% of AKI cases based on clinical diagnosis and 1.5% and 0.3% of AIN and ATN cases, respectively, based on pathological diagnosis. In patients with suspected intrinsic AKI, kidney biopsy should be performed for diagnosis of the precise etiology and selection of appropriate treatment.

Prediction and validation of nonalcoholic fatty liver disease by fatty liver index in a Japanese population.

Fatty liver index (FLI) calculated by using body mass index (BMI), waist circumference and levels of γ-glutamyl transferase and triglycerides is a non-invasive predictor of nonalcoholic fatty liver disease (NAFLD). The original study in Italy showed that the cutoff level for prediction of NAFLD was FLI ≥60. However, the sex difference in FLI was not taken into consideration, and it is unclear whether the cutoff value can be applied to other races. We investigated the cutoff value of FLI for prediction of NAFLD determined by abdominal ultrasonography using receiver operating characteristic curve analyses in 14,471 Japanese subjects (men/women: 9,240/5,231; mean age: 48 ± 9 years). There was a significant interaction between sex and FLI for detection of NAFLD (p < 0.001). The cutoff values of FLI in men and women were 35.1 (area under the curve [AUC]: 0.82) and 15.6 (AUC: 0.91), respectively. When the subjects were divided by the absence and presence of obesity (BMI ≥25), there was a significant interaction between FLI and obesity for detection of NAFLD in women (p < 0.001) but not in men (p = 0.679). The cutoff values of FLI in non-obese/obese men and women were 22.6/52.6 and 11.2/33.2, respectively. In conclusion, the cutoff value of FLI for prediction of NAFLD in Japanese individuals was lower than that in the original study, and there is a significant sex difference. The simple and useful cutoff values in Japanese men and women are FLI ≥35 (non-obese/obese: 23/53) and FLI ≥16 (non-obese/obese: 11/33), respectively.

Involvement of necroptosis in contrast-induced nephropathy in a rat CKD model.

BACKGROUND: The risk of contrast-induced nephropathy (CIN) is high in patients with chronic kidney disease (CKD). However, the mechanism of CIN in CKD is not fully understood. Here, we prepared a clinically relevant model of CIN and examined the role of necroptosis, which potentially cross-talks with autophagy, in CIN. METHODS: In Sprague-Dawley rats, CKD was induced by subtotal nephrectomy (SNx, 5/6 nephrectomy) 4 weeks before induction of CIN. CIN was induced by administration of a contrast medium (CM), iohexol, following administration of indomethacin and N-omega-Nitro-L-arginine methyl ester. Renal function and tissue injuries were assessed 48 h after CM injection. RESULTS: Serum creatinine (s-Cre) and BUN were increased from 0.28 ± 0.01 to 0.52 ± 0.02 mg/dl and from 15.1 ± 0.7 to 29.2 ± 1.2 mg/dl, respectively, after SNx alone. CM further increased s-Cre and BUN to 0.69 ± 0.03 and 37.2 ± 2.1, respectively. In the renal tissue after CM injection, protein levels of receptor-interacting serine/threonine-protein kinase (RIP) 1, RIP3, cleaved caspase 3, and caspase 8 were increased by 64 ~ 212%, while there was reduction in LC3-II and accumulation of p62. Necrostatin-1, an RIP1 inhibitor, administered before and 24 h after CM injection significantly suppressed elevation of s-Cre, BUN and urinary albumin levels, kidney injury molecule-1 expression and infiltration of CD68-positive macrophages in renal tissues after CM injection. CONCLUSION: The results suggest that necroptosis of proximal tubular cells contributes to CIN in CKD and that suppression of protective autophagy by pro-necroptotic signaling may also be involved.

Seasonal variation of serum 25-hydroxyvitamin D level in hemodialysis patients in the northernmost island of Japan.

BACKGROUND: Serum vitamin D level shows a seasonal variation, being lower in winter than in summer in healthy subjects. The aim of this study was to determine whether there is presence of such a seasonal variation in hemodialysis patients. METHODS: A total of 102 patients on hemodialysis were enrolled in February 2017 (winter) for analyses of serum levels of 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] and treatments for chronic kidney disease-mineral and bone disorder (CKD-MBD). The examinations were repeated in August 2017 (summer). After exclusion of patients with malignancy, loss of follow-up and missing data, 78 patients contributed to the analyses. RESULTS: Serum level of 25(OH)D, but not that of 1,25(OH)2D, was significantly lower in winter (14.0 ng/mL) than in summer (15.5 ng/mL), though there was no significant difference in regimen for CKD-MBD treatment including vitamin D receptor activators (VDRAs) between the two seasons. Serum intact parathyroid hormone level tended to be higher and alkaline phosphatase was significantly higher in winter than in summer. Linear mixed-effects model analysis showed that level of 25(OH)D, but not that of 1,25(OH)2D, was significantly associated with season (winter and summer) after adjustment of age, sex, dialysis vintage, albumin level and use of drugs for CKD-MBD. CONCLUSION: Serum 25(OH)D has a seasonal variation, being lower in winter than in summer, independent of CKD-MBD treatment including treatment with VDRAs in Japanese hemodialysis patients. The impact of the seasonal variation on risk of vitamin D deficiency and its effect on prognosis remain to be investigated.

Impact of atrial fibrillation on the risk of ischemic stroke in patients on hemodialysis: BOREAS-HD3 Study.

BACKGROUND: Atrial fibrillation (AF) is an established risk factor for ischemic stroke in a general population. However, its impact in patients on hemodialysis (HD), a group with a high risk for stroke, is still controversial. Here we examined this issue in a Japanese cohort. METHODS: This study was designed as a multicenter cohort study. HD patients (n = 1,067) were enrolled from 22 institutes in January 2009 and followed up for 3 years. Patients with missing data (n = 196) or kidney transplantation (n = 4) were excluded, and 867 patients contributed to the analysis of the risk of new-onset of ischemic stroke. RESULTS: At baseline, AF was observed in 123 patients (14.2%, AF group) and not in the others (n = 744: 85.8%, non-AF group). During a follow-up period of 31.3 months, the cumulative incidence rate for ischemic stroke was significantly higher in the AF group than in the non-AF group (6.5% vs. 2.9%, p < 0.05). In Cox regression analysis, AF was a significant independent risk factor for new-onset of ischemic stroke after adjustment for age, sex, prior history of ischemic stroke, use of warfarin, dialysis vintage, comorbidity of diabetic nephropathy, and interdialytic weight gain (hazard ratio 2.17-2.68). CONCLUSION: Present analyses using comprehensive adjustment for multiple confounders, including prior history of ischemic stroke, indicated that AF independently increases the risk of new-onset of ischemic stroke by more than twofold in Japanese HD patients.

Prediction of new onset of diabetes mellitus during a 10-year period by using a combination of levels of alanine aminotransferase and γ-glutamyl transferase.

Levels of alanine aminotransferase (ALT) and γ-glutamyl transferase (GGT) have been reported to be associated with increased risk of diabetes mellitus (DM). However, whether a combination of levels of ALT and GGT predicts new onset of DM better than does ALT or GGT alone in both males and females has not fully been addressed. We investigated the relationship between the combination of ALT and GGT and DM development during a 10-year follow-up period in 13,919 subjects (male/female: 8,983/4,936; age 48 ± 10 years) who received health examinations. During the 10-year period, 617 males (6.9%) and 153 females (3.1%) had new onset of DM. Multivariable Cox proportional hazard models with a restricted cubic spline showed that hazard ratios (HRs) of DM development increased with higher levels of ALT and GGT at baseline in both sexes after adjustment of confounding factors. When divided into 4 subgroups of high (H-) and low (L-) levels of ALT (male/female: 27/21 U/L) and GGT (male/female: 43/23 U/L) using cutoff values shown by receiver operating characteristic curve analyses, the adjusted HR in the H-ALT/H-GGT group was significantly higher than HR in the L-ALT/L-GGT group as the reference in males (HR [95% confidence interval]: 1.73[1.36-2.20], p < 0.001) but was not significantly higher in females (1.50 [0.97-2.33], p = 0.065). The addition of the combination of H-ALT/H-GGT to traditional risk factors with and without H-ALT or H-GGT alone significantly improved the discriminatory capability for predicting development of DM. In conclusion, the combination of H-ALT/H-GGT efficiently predicts development of DM in male individuals but not significantly in female individuals.

Significance of urinary fatty acid-binding protein 4 level as a possible biomarker for the identification of minimal change disease in patents with nephrotic-range proteinuria.

BACKGROUND: Fatty acid-binding protein 4 (FABP4), but not FABP1 (liver-type FABP), is ectopically induced in injured glomerular endothelial cells, and urinary FABP4 (U-FABP4) level is associated with proteinuria and renal dysfunction in a general population. METHODS: The clinical significance of U-FABP4 was investigated in 81 patients (male/female: 43/38, age: 57 ± 17 years) who underwent kidney biopsy. RESULTS: U-FABP4 was negatively correlated with estimated glomerular filtration rate (eGFR) (r = - 0.56, P < 0.01) and was positively correlated with age, blood pressure, triglycerides, proteinuria (r = 0.58, P < 0.01), plasma FABP4 and urinary FABP1 (U-FABP1) (r = 0.52, P < 0.01). Multivariable regression analysis showed that eGFR, proteinuria and U-FABP1 were independent predictors of U-FABP4. The level of U-FABP4, but not that of proteinuria, eGFR or U-FABP1, in minimal change nephrotic syndrome (MCNS) was significantly lower than the level in membranous nephropathy (MN) and that in diabetic nephropathy. Receiver operating characteristic curve analysis indicated that U-FABP4 level ≤ 0.78 µg/gCr predicted MCNS in patients who had nephrotic-range proteinuria with a high level of accuracy. When divided by the median value of U-FABP4 at baseline in 33 of the 81 patients who could be followed up, the yearly change (post-pre) in eGFR in the low U-FABP4 group was significantly greater than that in the high U-FABP4 group (median: 11.0 vs. -5.0 mL/min/1.73m2/year). CONCLUSIONS: U-FABP4 level is independently associated with proteinuria and renal dysfunction in patients with glomerular kidney disease. A low U-FABP4 level may predict MCNS in patients with nephrotic syndrome and would be a useful biomarker for differential diagnosis of MCNS and MN, which are common causes of nephrotic syndrome.

Annual change in plasma xanthine oxidoreductase activity is associated with changes in liver enzymes and body weight.

Xanthine oxidoreductase (XOR), an enzyme of uric acid formation from hypoxanthine and xanthine, is recognized as a source of oxidative stress. Plasma activity of XOR has been reported to be a biomarker of metabolic disorders associated with obesity, liver dysfunction, insulin resistance, hyperuricemia and adipokines. We investigated longitudinal change in plasma XOR activity, which was determined by using mass spectrometry and liquid chromatography to detect [13C2, 15N2]-uric acid using [13C2, 15N2]-xanthine as a substrate, in 511 subjects (male/female: 244/267) of the Tanno-Sobetsu Study in the years 2016 and 2017. Plasma XOR activity in a basal state was significantly higher in men than in women, but no significant sex difference was observed in annual change in plasma XOR activity. Annual change in plasma activity of XOR was positively correlated with changes in each parameter, including body weight (r = 0.203, p < 0.001), body mass index, diastolic blood pressure, aspartate transaminase (AST) (r = 0.772, p < 0.001), alanine transaminase (r = 0.647, p < 0.001), γ-glutamyl transpeptidase, total cholesterol, triglycerides, uric acid, fasting glucose and HbA1c. Multivariate regression analysis demonstrated that change in AST and that in body weight were independent predictors of change in plasma XOR activity after adjustment of age, sex and changes in each variable with a significant correlation without multicollinearity. In conclusion, annual change in plasma XOR activity is independently associated with changes in liver enzymes and body weight in a general population. Improvement of liver function and reduction of body weight would decrease plasma XOR activity and its related oxidative stress as a therapeutic strategy.

Plasma Xanthine Oxidoreductase Activity as a Novel Biomarker of Metabolic Disorders in a General Population.

BACKGROUND: Xanthine oxidoreductase (XOR) is an enzyme that catalyzes the formation of uric acid from hypoxanthine and xanthine, leading to an increase in superoxide and reactive oxygen species. Activation of XOR promotes oxidative stress-related tissue injury. We investigated the associations between metabolic parameters and plasma XOR activity measured by a sensitive and accurate assay using a combination of liquid chromatography and triple quadrupole mass spectrometry to detect [13C2,15N2]-uric acid using [13C2,15N2]-xanthine as a substrate.Methods and Results:A total of 627 Japanese subjects (M/F, 292/335) from the Tanno-Sobetsu Study, a population-based cohort, were recruited. Plasma XOR activity was significantly higher in males than in females, and habitual smoking was associated with elevation of activity. Plasma XOR activity was positively correlated with body mass index (BMI; r=0.323, P<0.001), waist circumference, blood pressure, and levels of liver enzymes including alanine transaminase (r=0.694, P<0.001), uric acid (r=0.249, P<0.001), triglycerides (r=0.312, P<0.001), hemoglobin A1c, fasting glucose, insulin and HOMA-R (r=0.238, P<0.001) as a marker of insulin resistance and was negatively correlated with high-density lipoprotein cholesterol level. On stepwise and multivariate regression analyses, BMI, smoking and levels of alanine transaminase, uric acid, triglycerides and HOMA-R were independent predictors of plasma XOR activity after adjustment for age and gender. CONCLUSIONS: Plasma XOR activity is a novel biomarker of metabolic disorders in a general population.

Circulating Fatty Acid-Binding Protein 4 Concentration Predicts the Progression of Carotid Atherosclerosis in a General Population Without Medication.

BACKGROUND: Fatty acid-binding protein 4 (FABP4), which is expressed in both adipocytes and macrophages, is secreted from the cells and acts as an adipokine. An elevated circulating FABP4 level is associated with insulin resistance and atherosclerosis.Methods and Results:We investigated the causative association between FABP4 level and progression of atherosclerosis in subjects of the Tanno-Sobetsu Study, a population-based cohort. In 281 subjects without medication (male/female: 109/172) in the year 2010 or 2013, the carotid intima-media thickness (CIMT) assessed using carotid ultrasonography was significantly correlated with age, adiposity, blood pressure, renal dysfunction and levels of cholesterol, triglycerides, fasting glucose, HbA1c and FABP4 (r=0.331, P<0.001). Multiple regression analysis demonstrated that age, sex and FABP4 concentration were independent predictors of CIMT. A total of 78 (male/female: 29/49) of the 156 subjects in 2010 underwent carotid ultrasonography again in 2013. The change in CIMT each year during that 3-year period (mean±SD: 3.8±22.3 µm/year) was positively correlated with basal levels of high-sensitivity C-reactive protein (hsCRP) (r=0.231, P=0.046) and FABP4 (r=0.267, P=0.018) in 2010. After adjustment for age, sex and hsCRP level, the basal FABP4 level was independently associated with the change in CIMT per year. CONCLUSIONS: FABP4 concentration is an independent predictor of the progression of carotid atherosclerosis.

Unexpected high plasma xanthine oxidoreductase activity in female subjects with low levels of uric acid.

Hypouricemia is a high-risk factor of exercise-induced acute kidney injury (EIAKI) probably through a lack of an antioxidant effect of uric acid. Xanthine oxidoreductase (XOR) is an enzyme that catalyzes the formation of uric acid from hypoxanthine and xanthine, leading to an increase in superoxide and reactive oxygen species. Activation of XOR has been proposed to promote oxidative stress-related tissue injury. We measured plasma XOR activity by a sensitive and accurate assay using a combination of liquid chromatography and triple quadrupole mass spectrometry in subjects with relatively low levels of uric acid (≤4.0 mg/dL) who were recruited from 627 subjects (male/female: 292/335) in the Tanno-Sobetsu Study, a population-based cohort. The numbers of subjects with uric acid ≤4.0 mg/dL, ≤3.0 mg/dL and ≤2.0 mg/dL were 72 (11.5%, male/female: 5/67), 13 (2.1%, all females) and 2 (0.3%, both females), respectively. Plasma XOR activities in 5 male subjects were below the median value of the 292 male subjects. In 12 (17.9%) of the 67 female subjects with uric acid ≤4.0 mg/dL, plasma XOR activities were above the upper quartile value of the 335 female subjects. Eleven of the 12 female subjects with high plasma XOR activity and a low uric acid level had liver dysfunction and/or insulin resistance. In conclusion, unexpected high plasma XOR activities were found in some female subjects with relatively low levels of uric acid. Measurement of plasma XOR activity may help to identify hypouricemic patients with a high risk for EIAKI.

Local Production of Fatty Acid-Binding Protein 4 in Epicardial/Perivascular Fat and Macrophages Is Linked to Coronary Atherosclerosis.

OBJECTIVE: Fatty acid-binding protein 4 (FABP4) is expressed in adipocytes and macrophages, and elevated circulating FABP4 level is associated with obesity-mediated metabolic phenotype. We systematically investigated roles of FABP4 in the development of coronary artery atherosclerosis. APPROACH AND RESULTS: First, by immunohistochemical analyses, we found that FABP4 was expressed in macrophages within coronary atherosclerotic plaques and epicardial/perivascular fat in autopsy cases and macrophages within thrombi covering ruptured coronary plaques in thrombectomy samples from patients with acute myocardial infarction. Second, we confirmed that FABP4 was secreted from macrophages and adipocytes cultured in vitro. Third, we investigated the effect of exogenous FABP4 on macrophages and human coronary artery-derived smooth muscle cells and endothelial cells in vitro. Treatment of the cells with recombinant FABP4 significantly increased gene expression of inflammatory markers in a dose-dependent manner. Finally, we measured serum FABP4 level in the aortic root (Ao-FABP4) and coronary sinus (CS-FABP4) of 34 patients with suspected or known coronary artery disease. Coronary stenosis score assessed by the modified Gensini score was weakly correlated with CS-FABP4 but was not correlated with Ao-FABP4. A stronger correlation (r=0.59, P<0.01) was observed for the relationship between coronary stenosis score and coronary veno-arterial difference in FABP4 level, (CS-Ao)-FABP4, indicating local production of FABP4 during coronary circulation in the heart. Multivariate analysis indicated that (CS-Ao)-FABP4 was an independent predictor of the severity of coronary stenosis after adjustment of conventional risk factors. CONCLUSIONS: FABP4 locally produced by epicardial/perivascular fat and macrophages in vascular plaques contributes to the development of coronary atherosclerosis.

Impact of the Number of Anti-Thrombosis Agents in Hemodialysis Patients: BOREAS-HD2 Study.

BACKGROUND/AIMS: Relationships between the number of anti-thrombosis agents, clinical benefits and adverse events in hemodialysis (HD) patients are unclear. METHODS: All patients on HD in 22 institutes (n = 1,071) were enrolled and followed up for 3 years. After exclusion of patients with missing data, kidney transplantation or retraction of consent during the follow-up period (n = 204), mortality rate and ischemic and hemorrhagic events were compared between different regimens of anti-thrombosis agents. RESULTS: The use of dual or triple antiplatelet (AP) agents (HR:2.03, 95% CI:1.01-4.13, p = 0.04) and the combination of an AP agent and warfarin (WF) (HR:4.84, 95%CI 1.96-11.96, p < 0.001) were associated with an increase in hemorrhagic events compared with no use of anti-thrombosis agents. No anti-thrombosis regimen was associated with a significant change in risk of ischemic stroke. The use of dual or triple AP agents, but not WF, was associated with an increase in cardiovascular mortality (HR:2.48, 95% CI:1.24-4.76, p = 0.01). CONCLUSION: A significant increase in hemorrhagic events by the use of dual or more AP agents and by co-administration of an AP agent and WF in patients on HD should be considered in planning their anti-thrombosis regimen.

Impact of use of angiotensin II receptor blocker on all-cause mortality in hemodialysis patients: prospective cohort study using a propensity-score analysis.

BACKGROUND: It is controversial whether treatment with an angiotensin II receptor blocker (ARB) or a calcium channel blocker (CCB) improves prognosis of hemodialysis (HD) patients. METHODS: This study was designed as a multicenter prospective cohort study. HD patients (n = 1071) were enrolled from 22 institutes in January 2009 and followed up for 3 years. Patients with missing data, kidney transplantation or retraction of consent during the follow-up period (n = 204) were excluded, and 867 patients contributed to analysis of mortality. Propensity score (PS) for use of ARB and that for CCB was calculated using a multiple logistic regression model. RESULTS: ARB and CCB were prescribed in 45.6 and 54.7 % of patients at enrollment. During the 3-year follow-up period, all-cause mortality and cardiovascular mortality rates were 18.8 and 5.1 %, respectively. Kaplan-Meier curves showed that all-cause and cardiovascular mortality rates were lower in the ARB group than in the non-ARB group, though the mortality rates were similar in the CCB group and non-CCB group. In PS-stratified Cox regression analysis, ARB treatment was associated with 34 and 45 % reduction of all-cause death and cardiovascular death, respectively. In PS matching analysis, ARB treatment was associated with a significant reduction (46 % reduction) in the risk of all-cause death. A significant impact of CCB treatment on all-cause or cardiovascular mortality was not detected in PS analysis. CONCLUSIONS: The use of an ARB, but not a CCB, is associated with reduced all-cause and cardiovascular mortalities in patients on HD.

Reduction of circulating FABP4 level by treatment with omega-3 fatty acid ethyl esters.

BACKGROUND: Fatty acid-binding protein 4 (FABP4/A-FABP/aP2) mainly expressed in adipocytes is secreted and acts as an adipokine. Increased circulating FABP4 level is associated with obesity, insulin resistance and atherosclerosis. However, little is known about the modulation of serum FABP4 level by drugs including anti-dyslipidemic agents. METHODS: Patients with dyslipidemia were treated with omega-3 fatty acid ethyl esters (4 g/day; n = 14) containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for 4 weeks. Serum FABP4 level was measured before and after treatment. Expression and secretion of FABP4 were also examined in mouse 3T3-L1 adipocytes treated with EPA or DHA. RESULTS: Treatment with omega-3 fatty acid ethyl esters significantly decreased triglycerides and serum FABP4 level (13.5 ± 1.5 vs. 11.5 ± 1.1 ng/ml, P = 0.017). Change in FABP4 level by omega-3 fatty acids was negatively correlated with change in levels of EPA + DHA (r = -0.643, P = 0.013), EPA (r = -0.540, P = 0.046) and DHA (r = -0.650, P = 0.011) but not change in the level of triglycerides or other fatty acid composition. Treatment of 3T3-L1 adipocytes with EPA or DHA had no effect on short-term (2 h) secretion of FABP4. However, gene expression and long-term (24 h) secretion of FABP4 were significantly reduced by treatment with EPA or DHA. CONCLUSIONS: Omega-3 fatty acids decrease circulating FABP4 level, possibly by reducing expression and consecutive secretion of FABP4 in adipocytes. Reducing FABP4 level might be involved in suppression of cardiovascular events by omega-3 fatty acids.