Department of Internal Medicine II, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany.
Institute for Clinical Epidemiology and Applied Biometry, University of Tübingen, Tübingen, Germany.
Nephrol Dial Transplant. 2018 Jan 1;33(1):34-43. doi: 10.1093/ndt/gfx206.
High mortality of haemodialysis patients is associated with systemic chronic inflammation and overactivation of the renin-angiotensin system (RAS). Insufficient elimination of pro-inflammatory immune mediators, especially in the molecular weight range of 15-45 kDa, may be one of the reasons for this. Employment of haemodialysis membranes with increased permeability was shown to ameliorate the inflammatory response and might modulate the effects of local RAS. In this study, we tested the impact of high cut-off (HCO), medium cut-off (MCO) and high-flux (HF) dialysis on leucocytic transcripts of angiotensin-converting enzymes (ACE and ACE2). Additionally, the impact of HCO, MCO and HF sera and dialysates on local ACEs and inflammation markers was tested in THP-1 monocytes.
Patients' leucocytes were obtained from our recent clinical studies comparing HCO and MCO dialysers with HF. The cells were subjected to quantitaive polymerase chain reaction (qPCR) analyses with TaqMan probes specific for ACE, ACE2 and angiotensin II (AngII) and Ang1-7 receptors. Sera and dialysates from the clinical trials as well as samples from in vitro dialysis were tested on THP-1 monocytic cells. The cells were subjected to qPCR analyses with TaqMan probes specific for ACE, ACE2, interleukin-6 and tumour necrosis factor α and immunocytochemistry with ACE and ACE2 antibodies.
Leucocytes obtained from patients treated with HCO or MCO demonstrated decreased transcript expression of ACE, while ACE2 was significantly upregulated as compared with HF. Receptors for AngII and Ang1-7 remained unchanged. THP-1 monocytes preconditioned with HCO and MCO patients' or in vitro dialysis sera reflected the same expressional regulation of ACE and ACE2 as those observed in HCO and MCO leucocytes. As a complementary finding, treatment with HCO and MCO in vitro dialysates induced a pro-inflammatory response of the cells as demonstrated by elevated messenger RNA expression of tumour necrosis factor α and interleukin-6, as well as upregulation of ACE and decreased levels of ACE2.
Taken together, these data demonstrate that employment of membranes with high permeability eliminates a spectrum of mediators from circulation that affect the RAS components in leucocytes, especially ACE/ACE2.
血液透析患者死亡率高与全身慢性炎症和肾素-血管紧张素系统（RAS）过度激活有关。不能充分清除促炎免疫介质，特别是分子量在 15-45 kDa 范围内的介质，可能是其中一个原因。使用通透性更高的血液透析膜可改善炎症反应，并可能调节局部 RAS 的作用。在这项研究中，我们测试了高通量（HCO）、中通量（MCO）和高流量（HF）透析对白细胞血管紧张素转换酶（ACE 和 ACE2）转录物的影响。此外，还在 THP-1 单核细胞中测试了 HCO、MCO 和 HF 血清和透析液对局部 ACE 和炎症标志物的影响。
从我们最近的比较 HCO 和 MCO 透析器与 HF 的临床研究中获得患者的白细胞。用 TaqMan 探针进行定量聚合酶链反应（qPCR）分析，该探针特异性针对 ACE、ACE2 和血管紧张素 II（AngII）和 Ang1-7 受体。来自临床试验的血清和透析液以及体外透析样本用于 THP-1 单核细胞。用 TaqMan 探针进行 qPCR 分析，该探针特异性针对 ACE、ACE2、白细胞介素 6 和肿瘤坏死因子 α，并进行 ACE 和 ACE2 抗体的免疫细胞化学分析。
与 HF 相比，用 HCO 或 MCO 治疗的患者获得的白细胞 ACE 转录物表达降低，而 ACE2 明显上调。AngII 和 Ang1-7 的受体保持不变。用 HCO 和 MCO 患者的或体外透析血清预处理的 THP-1 单核细胞反映了与 HCO 和 MCO 白细胞中观察到的 ACE 和 ACE2 相同的表达调节。作为补充发现，体外透析液中 HCO 和 MCO 的治疗诱导细胞产生促炎反应，表现为肿瘤坏死因子 α 和白细胞介素 6 的信使 RNA 表达升高，以及 ACE 的上调和 ACE2 水平降低。
总之，这些数据表明，使用高通透性膜可从循环中清除影响白细胞 RAS 成分的一系列介质，特别是 ACE/ACE2。
