Ando M, Shibuya A, Tsuchiya K, Akiba T, Nitta K
Department of Nephrology, Tokyo Metropolitan Komagome Hospital, Bunkyo-Ku, Tokyo, Japan.
Kidney Int. 2006 Jul;70(2):358-62. doi: 10.1038/sj.ki.5001548. Epub 2006 May 31.
Toll-like receptors (TLRs) play a pivotal role in pathogen recognition and subsequent cytokine synthesis by immune cells. Uremic patients have a high infectious morbidity, but it remains unclear if this arises from the defective innate immune responses related to TLRs. We studied TLR4 expression in monocytes and their intracellular cytokine synthesis in response to lipopolysaccharide (LPS) stimulation in 35 predialysis patients with chronic kidney disease (CKD) with or without predisposition to bacterial infections and 16 age-matched controls. Expression of TLR4 in unstimulated peripheral monocytes was determined by staining with anti-TLR4 antibody and analysis with flow cytometry. Monocytes were then stimulated by LPS, labeled with anti-CD14 antibody, and subjected to intracellular cytokine staining and flow cytometry. Tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, and IL-8 synthesis was examined in CD14(+) monocytes. TLR4 expression was constitutively diminished in CKD patients with reduced expression being more severe in those CKD patients who were predisposed to infections. Monocytes from these infection prone CKD patients exhibited significantly reduced synthesis of TNF-alpha, IL-1beta, IL-6, and IL-8 in response to LPS challenge compared with those from control subjects. The intensity of synthesis of each cytokine significantly correlated with TLR4 expression levels in monocytes (P<0.01). The capacity of monocytes to synthesize proinflammatory cytokines was significantly reduced in infection prone CKD patients, and this may possibly be due to the reduced monocyte expression of TLR4. Abnormal TLR4 expression by monocytes may play a role in the susceptibility of such patients to bacterial infections.
Toll样受体（TLRs）在病原体识别以及免疫细胞随后的细胞因子合成过程中发挥着关键作用。尿毒症患者具有较高的感染发病率，但目前尚不清楚这是否源于与TLRs相关的先天性免疫反应缺陷。我们研究了35例患有或不患有细菌感染易感性的慢性肾脏病（CKD）透析前患者以及16例年龄匹配的对照者中单核细胞TLR4的表达及其对脂多糖（LPS）刺激的细胞内细胞因子合成情况。通过用抗TLR4抗体染色并进行流式细胞术分析来测定未刺激外周单核细胞中TLR4的表达。然后用LPS刺激单核细胞，用抗CD14抗体标记，并进行细胞内细胞因子染色和流式细胞术检测。在CD14(+)单核细胞中检测肿瘤坏死因子（TNF）-α、白细胞介素（IL）-1β、IL-6和IL-8的合成。CKD患者中TLR4的表达呈组成性降低，在那些易感染的CKD患者中表达降低更为严重。与对照组相比，这些易感染CKD患者的单核细胞在受到LPS刺激后，TNF-α、IL-1β、IL-6和IL-8的合成显著减少。每种细胞因子的合成强度与单核细胞中TLR4的表达水平显著相关（P<0.01）。易感染CKD患者单核细胞合成促炎细胞因子的能力显著降低，这可能是由于单核细胞TLR4表达降低所致。单核细胞TLR4表达异常可能在此类患者对细菌感染的易感性中起作用。
