Su Mi Lee

Omega-3 fatty acid supplementation increases 1,25-dihydroxyvitamin D and fetuin-A levels in dialysis patients

Vitamin D deficiency, low levels of fetuin-A, and fibroblast growth factor 23 (FGF-23) are related to vascular calcification, which is associated with cardiovascular disease. We hypothesized that omega-3 fatty acid (FA), which has cardioprotective properties, modifies vitamin D status, fetuin-A, and FGF-23 levels in dialysis patients. In a randomized, open-label, controlled study, a total of 47 patients treated with dialysis for at least 1 year were randomized to treatment for 6 months with omega-3 FAs (Omacor, 3 g/d; Pronova, Sandefjord, Norway) or a control group. Levels of fetuin-A and FGF-23 were measured by enzyme-linked immunoassay, 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D were measured by radioimmunoassay. The mean age of the enrolled patients was 57.4 ± 10.4 years, and mean dialysis duration was 46.5 ± 28.1 months. Twenty-seven hemodialysis patients and 16 peritoneal dialysis patients finished this trial. After 6 months, the levels of 1,25-dihydroxyvitamin D and fetuin-A were significantly increased in the group taking the omega-3 FA supplement compared with baseline. Levels of calcium, phosphorous, parathyroid hormone, 25-hydroxyvitamin D, FGF-23, and lipid profiles were not significantly changed in the omega-3 FA-supplemented group after 6 months compared with baseline. The erythrocyte membrane contents of eicosapentaenoic acid and docosahexaenoic acid were significantly increased, and oleic acid content was significantly decreased in the omega-3 FA-supplemented group after 6 months compared with baseline. Regarding vascular calcification and cardiovascular disease, omega-3 FA supplementation may have a clinical benefit caused by activating vitamin D, increasing fetuin-A levels, and modifying erythrocyte membrane FA contents in dialysis patients.

Association between body fat and vitamin D status in Korean adults.

The relationship between body fat mass and vitamin D appears to vary by ethnicity, but our understanding of this predisposition in Asians is limited due to the scarcity of prior investigations. Data on 1,697 Korean adults were obtained from the second and third years (2008-2009) of the fourth Korean National Health and Nutritional Examination Survey. Body fat mass was measured using dual-energy X-ray absorptiometry. Both linear regression analysis for serum 25-hydroxyvitamin D [25(OH)D] and logistic analysis for vitamin D deficiency [25(OH)D <20 ng/mL] were performed to determine significant predictors among BMI, waist circumference (WC), and body fat percentage (BF), after adjustment of multiple covariates. To explore a possible non-linear relationship between them, the fractional polynomials method was used. All analyses were conducted following stratification by sex. In linear regression analysis, BMI and WC were not associated with 25(OH)D. However, BF was inversely related to 25(OH)D, irrespective of the fat location (both appendicular and truncal fat) in both sexes. In logistic regression analysis, the highest quartile group of BF had a greater OR for vitamin D deficiency than the lower quartile groups, irrespective of the fat location and sex. However, the quartiles of BMI and WC were not associated with vitamin D deficiency. The linear relationships between BF and 25(OH)D (or vitamin D deficiency) were confirmed despite use of the fractional polynomials method. Body fat mass is inversely associated with serum 25(OH)D in Korean adults. Monitoring of vitamin D deficiency in Korean adults with high fat mass is needed.

Cardioprotective Effects of ω-3 PUFAs in Chronic Kidney Disease

The prevalence rate of chronic kidney disease (CKD) is increasing worldwide, and cardiovascular disease (CVD) is a main cause of death in patients with CKD. The high incidence of CVD in CKD patients is related to chronic inflammation, dyslipidemia, malnutrition, atherosclerosis, and vascular calcification. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) have been shown to reduce the risk of CVD. In this paper, we review the beneficial effects of ω-3 PUFAs on CVD and the possible cardioprotective mechanisms of ω-3 PUFAs in CKD patients by determining the effect of ω-3 PUFAs in the general population. ω-3 PUFAs have several cardioprotective benefits, such as reducing inflammation, decreasing oxidative stress, inhibiting platelet activity, exerting antiarrhythmic effects, and improving triglyceride levels, in the general population and patients with CKD. Modifications of erythrocyte membrane fatty acid content, including an increased ω-3 index and decreased oleic acid, after ω-3 PUFAs supplementation are important changes related to CVD risk reduction in the general population and patients with CKD. Further basic and clinical studies are essential to confirm the effects of ω-3 PUFAs on vitamin D activation, vascular calcification prevention, cardiovascular events, and mortality in CKD patients.

Rosuvastatin Attenuates Inflammation, Apoptosis and Fibrosis in a Rat Model of Cyclosporine-Induced Nephropathy

Background/Aim: Cyclosporine (CsA)-induced kidney injury is characterized by renal dysfunction with inflammatory cell infiltrations, apoptosis and fibrosis. Pleiotropic effects of statins may exert anti-inflammatory, antiapoptotic and antifibrotic actions beyond lipid control. The aim of this study is to investigate whether rosuvastatin (RUS) has anti-inflammatory, antiapoptotic and antifibrotic effects on chronic CsA-induced nephropathy in a rat model. Methods: Male Sprague-Dawley rats fed a low-sodium diet were divided into three treatment groups: control (0.9% saline injection), CsA (15 mg/kg/day by subcutaneous injection), CsA + RUS (10 mg/kg/day by gastric gavage). Renal function, CsA level and lipid levels were measured at the end of 4 weeks. The expression of ED-1, transforming growth factor-β1 (TGF-β1) and α-smooth muscle actin (α-SMA) for inflammation and fibrosis were examined by Western blot analysis. The expression levels of apoptosis-associated factors were examined by Western blot analysis. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase-mediated biotin nick end-labeling (TUNEL) method. Results: Kidney function was decreased in CsA-treated rats compared with controls, which was attenuated by RUS. RUS did not affect the lipid level or the blood CsA level. TUNEL staining showed that RUS inhibited CsA-induced tubular apoptosis. RUS decreased CsA-induced increased expression of Bax/Bcl-2 ratio. The expressions of ED-1, α-SMA, TGF-β1, Smad2/3, Smad4 and p-JNK were increased in CsA-treated rats, which were attenuated by RUS. Tubular atrophy and interstitial fibrosis in CsA-treated rats were attenuated by RUS supplementation. Conclusion: RUS supplementation attenuates proinflammatory and apoptosis-related factors and inhibits the fibrotic pathways including the smad-dependent and smad-independent pathways in a rat model of CsA-induced nephropathy.

Circulating TNF receptors are significant prognostic biomarkers for idiopathic membranous nephropathy.

Idiopathic membranous nephropathy (iMN) is a common cause of nephrotic syndrome in adults. A biomarker to accurately indicate the severity of iMN and predict long-term prognosis is insufficient. Here, we evaluated the clinical significance of circulating tumor necrosis factor receptors (cTNFRs) as prognostic biomarkers of iMN with nephrotic syndrome. A total of 113 patients with biopsy-proven iMN and 43 healthy volunteers were enrolled in this study. Ninety patients with iMN had nephrotic range proteinuria. Levels of cTNFRs were measured by using serum samples collected at the time of initial diagnosis. Levels of cTNFRs were higher in the patients with nephrotic syndrome than in those with subnephrotic range proteinuria or in the healthy volunteers (P for trend <0.001). Estimated glomerular filtration rate and proteinuria tended to worsen as the cTNFRs levels increased. Having a cTNFR1 level within the highest tertile was a significant risk factor for renal progression after adjustment, in comparison with the other tertiles (hazard ratio [HR], 3.39; 95% confidence interval [95% CI], 1.48–7.78; P = 0.004). The cTNFR2 level within the highest tertile also significantly increased the risk of renal progression (HR, 3.29; 95% CI, 1.43–7.54; P = 0.005). Renal tubular TNFRs expression was associated with cTNFRs level. However, the cTNFRs levels were not associated with autoantibody against phospholipase A2 receptor reactivity/levels or treatment response. This study demonstrated that cTNFRs levels at the time of initial diagnosis could predict renal progression in patients with iMN.

The effects of omega-3 fatty acid on vitamin D activation in hemodialysis patients: a pilot study.

The high incidence of cardiovascular disease and vitamin D deficiency in chronic kidney disease patients is well known. Vitamin D activation by omega-3 fatty acid (FA) supplementation may explain the cardioprotective effects exerted by omega-3 FA. We hypothesized that omega-3 FA and 25-hydroxyvitamin D (25(OH)D) supplementation may increase 1,25-dihydroxyvitamin D (1,25(OH)2D) levels compared to 25(OH)D supplementation alone in hemodialysis (HD) patients that have insufficient or deficient 25(OH)D levels. We enrolled patients that were treated for at least six months with 25(OH)D < 30 ng/mL (NCT01596842). Patients were randomized to treatment for 12 weeks with cholecalciferol supplemented with omega-3 FA or a placebo. Levels of 25(OH)D and 1,25(OH)2D were measured after 12 weeks. The erythrocyte membrane FA contents were also measured. Levels of 25(OH)D were increased in both groups at 12 weeks compared to baseline. The 1,25(OH)2D levels at 12 weeks compared to baseline showed a tendency to increase in the omega-3 FA group. The oleic acid and monounsaturated FA content decreased, while the omega-3 index increased in the omega-3 FA group. Omega-3 FA supplementation may be partly associated with vitamin D activation, although increased 25(OH)D levels caused by short-term cholecalciferol supplementation were not associated with vitamin D activation in HD patients.

Cadmium exposure induces hematuria in Korean adults

INTRODUCTION Toxic heavy metals have adverse effects on human health. However, the risk of hematuria caused by heavy metal exposure has not been evaluated. METHODS Data from 4701 Korean adults were obtained in the Korean National Health and Nutritional Examination Survey (2008-2010). Blood levels of the toxic heavy metals cadmium, lead, and mercury were measured. Hematuria was defined as a result of ≥+1 on a urine dipstick test. The odds ratios (ORs) for hematuria were measured according to the blood heavy metal levels after adjusting for multiple variables. RESULTS Individuals with blood cadmium levels in the 3rd and 4th quartiles had a greater OR for hematuria than those in the 1st quartile group: 3rd quartile, 1.35 (1.019-1.777; P=0.037); 4th quartile, 1.52 (1.140-2.017; P=0.004). When blood cadmium was considered as a log-transformed continuous variable, the correlation between blood cadmium and hematuria was significant: OR, 1.97 (1.224-3.160; Ptrend=0.005). In contrast, no significant correlations between hematuria and blood lead or mercury were found in the multivariate analyses. DISCUSSION The present study shows that high cadmium exposure is associated with a risk of hematuria.

Non-Linear Relationship between Serum 25-Hydroxyvitamin D and Hemoglobin in Korean Females: The Korean National Health and Nutrition Examination Survey 2010–2011

Background Anemia and vitamin D deficiency are both important health issues; however, the nature of the association between vitamin D and either hemoglobin or anemia remains unresolved in the general population. Methods Data on 11,206 adults were obtained from the fifth Korean National Health and Nutritional Examination Survey. A generalized additive model was used to examine the threshold level for relationship between serum 25-hydroxyvitamin D [25(OH)D] and hemoglobin levels. A multivariate logistic regression for anemia was conducted according to 25(OH)D quintiles. All analyses were stratified according to sex and menstrual status. Results The generalized additive model confirmed a threshold 25(OH)D level of 26.4 ng/mL (male, 27.4 ng/mL; premenopausal females, 11.8 ng/mL; postmenopausal females, 13.4 ng/mL). The threshold level affected the pattern of association between 25(OH)D and anemia risk: the odds ratio of the 1st quintile but not the 2nd, 3rd, and 4th quintiles were significantly different from the 5th quintile in both premenopausal and postmenopausal females, however there was no obvious trend in males. Conclusions This population-based study demonstrated a non-linear relationship with a threshold effect between serum 25(OH)D and hemoglobin levels in females. Further interventional studies are warranted to determine whether the appropriate level of hemoglobin can be achieved by the correction of vitamin D deficiency.

Correlation between periodontitis and chronic kidney disease in Korean adults

Background Periodontitis and chronic kidney disease (CKD) are important health issues; however, the association between periodontitis and CKD markers, especially in Korean adults, remains elusive. Methods Data on 15,729 Korean adults were obtained from the Korean National Health and Nutritional Examination Surveys IV and V. The CKD markers included a decreased estimated glomerular filtration rate (eGFR;<60 mL/min/1.73 m2), proteinuria, and hematuria. Odds ratios (ORs) and 95% confidence intervals were measured using stepwise multivariate logistic regression analyses for CKD markers based on the presence of periodontitis. Results Patients with periodontitis had greater unadjusted ORs for CKD markers compared to those without periodontitis, as follows: decreased eGFR, 4.07 (3.11–5.33); proteinuria, 2.12 (1.48–3.05); and hematuria, 1.25 (1.13–1.39, all P<0.001). Periodontitis was a significant predictor of decreased eGFR independent of all covariates [1.39 (1.03–1.89), P=0.034]. However, the effect of periodontitis on decreased eGFR seemed to be affected by hypertension and diabetes mellitus. Periodontitis was not an independent predictor of proteinuria; the significance disappeared after adjusting for hypertension and diabetes mellitus. Periodontitis was significantly correlated with hematuria, leading to similar ORs regardless of the adjustment for covariates [1.29 (1.15–1.46), P<0.001]. Conclusion This study confirms the correlation between periodontitis and CKD markers, including decreased eGFR, proteinuria, and hematuria in Korean adults.

Vascular Calcification on Plain Radiographs Is Related with the Severity of Lesions Detected by Coronary Angiography in Dialysis Patients

Coronary artery disease (CAD) is a primary cause of mortality and morbidity in dialysis patients. However, it is difficult to select the proper point for coronary angiographic procedure, because dialysis patients frequently do not display typical symptoms. Vascular calcification (VC) scores of artery or aorta on plain radiographs are associated with CAD events and may be predictive of CAD in dialysis patients. Therefore, we evaluated whether high or meaningful VC scores on plain radiographs are related with the severity of lesions detected by coronary angiography (CAG) in dialysis patients. We retrospectively enrolled dialysis patients who underwent CAG and checked several plain radiographs within one year before or after CAG. Significant VC is defined as high or meaningful VC scores, such as long abdominal aortic calcification and medial artery calcification on feet. Of all 55 patients, 41 patients (74.5%) exhibited significant VC on plain radiographs and 23 patients (41.8%) underwent stent insertion. Among the 23 patients, longer stents were used in 18 patients with significant VC (34.1 ± 19.5 mm vs. 16.6 ± 15.2 mm, P = 0.029). Patients with significant VC showed higher prevalence rate of severe coronary artery calcification (P = 0.007) and diffuse/tubular stenosis (P = 0.012), detected by CAG, than those without significant VC. Thus, high or meaningful VC scores on plain radiographs were associated with the degree of calcification or stenosis detected by CAG. In conclusion, VC scores on plain radiographs may be predictive of calcification or stenosis of coronary artery before CAG in dialysis patients.