Cai Ling L, Pan Yu, Guo Li L, Zhu Xiao J, Gao Feng H, Tan Long Y, Xu Qin J, Jin Hui M
Division of Nephrology, No. 3 People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai - PR China.
Int J Artif Organs. 2012 May;35(5):360-8. doi: 10.5301/ijao.5000043.
Previous study has shown an independent association of low body fat percentage and fat loss over time with higher mortality in hemodialysis (HD) patients. High-purity dialysis fluid (HPDF) used in place of conventional dialysis fluid (CDF) may decrease inflammation and improve nutritional status. Its effect on adipocytes and therefore fat storage is unclear. The purpose of this study was to assess the effects of these dialysates on apoptosis and insulin resistance in cultured adipocytes to determine a basis for the superiority of HPDF.
Flow cytometry and fluorescence staining were used to evaluate apoptosis in adipocytes. Insulin receptor substrate-1 (IRS-1) and -2 and serine phosphorylation of IRS-1 levels were assayed by Western blot. Tumor necrosis factor a (TNFa) levels were measured by enzyme-linked immunosorbent assay (ELISA).
Although CDF contained more bacteria (66 ± 6 CFU/mL) than HPDF (7 ± 3 CFU/mL) and higher levels of bacterial DNA, endotoxin levels were similar. Combined with uremic serum (containing high TNFa levels), CDF (vs. HPDF) induced more apoptosis in adipocytes. Exposure to CDF also decreased expression of IRS-1 protein, increased expression of IRS-2 protein and insulin-stimulated serine phosphorylation of IRS-1, and decreased glucose consumption. Additionally, the culture supernatant from adipocytes exposed to CDF plus uremic serum for 48 hours contained significantly higher levels of TNFa (15.17 ± 2.89 vs. 8.12 ± 0.54 pg/mL [HPD plus uremic serum], p<0.0001).
The advantage of HPDF over CDF may be due to lower levels of dialysis fluid impurities.
先前的研究表明，随着时间的推移，低体脂百分比和脂肪减少与血液透析（HD）患者较高的死亡率存在独立关联。使用高纯度透析液（HPDF）代替传统透析液（CDF）可能会减轻炎症并改善营养状况。其对脂肪细胞及脂肪储存的影响尚不清楚。本研究的目的是评估这些透析液对培养的脂肪细胞凋亡和胰岛素抵抗的影响，以确定HPDF优越性的依据。
采用流式细胞术和荧光染色评估脂肪细胞凋亡。通过蛋白质免疫印迹法检测胰岛素受体底物-1（IRS-1）和-2以及IRS-1水平的丝氨酸磷酸化。采用酶联免疫吸附测定（ELISA）测量肿瘤坏死因子α（TNFα）水平。
尽管CDF中的细菌含量（66±6 CFU/mL）高于HPDF（7±3 CFU/mL），且细菌DNA水平更高，但内毒素水平相似。与尿毒症血清（TNFα水平较高）联合使用时，CDF（与HPDF相比）诱导脂肪细胞发生更多凋亡。暴露于CDF还会降低IRS-1蛋白的表达，增加IRS-2蛋白的表达以及胰岛素刺激的IRS-1丝氨酸磷酸化，并降低葡萄糖消耗。此外，暴露于CDF加尿毒症血清48小时的脂肪细胞培养上清液中TNFα水平显著更高（15.17±2.89 vs. 8.12±0.54 pg/mL [HPDF加尿毒症血清]，p<0.0001）。
HPDF优于CDF可能是由于透析液杂质水平较低。
