Benigni Ariela, Caroli Cristina, Longaretti Lorena, Gagliardini Elena, Zoja Carla, Galbusera Miriam, Moioli Daniela, Romagnani Paola, Tincani Angela, Andreoli Laura, Remuzzi Giuseppe
Mario Negri Institute for Pharmacological Research, Bergamo, Italy.
Arthritis Rheum. 2007 May;56(5):1569-78. doi: 10.1002/art.22524.
Toll-like receptor 9 (TLR-9), a receptor for CpG DNA, has been implicated in the activation of immune cells in lupus. We undertook this study to determine whether the expression of TLR-9 in resident renal cells in lupus nephritis is related to the development of tubulointerstitial injury.
TLR-9 was analyzed in selectively retrieved renal tissue from (NZB x NZW)F1 mice at different stages of disease by laser capture microdissection combined with real-time quantitative reverse transcriptase-polymerase chain reaction, and in renal biopsy specimens from lupus nephritis patients by immunohistochemistry. We investigated for the molecular component responsible for TLR-9 activation by cultured proximal tubular cells in serum from patients with lupus.
Renal tissue from NZB x NZW mice displayed robust TLR-9 expression localized to proximal tubular cells. TLR-9 levels correlated with proteinuria and tubulointerstitial injury to the extent that a cyclin-dependent kinase inhibitor, while reducing proteinuria and renal structural damage, prevented tubular TLR-9 generation in lupus mice. Consistently, exaggerated TLR-9 staining was found in proximal tubular cells of lupus patients, which correlated with tubulointerstitial damage. DNA-containing immune complexes purified from sera of patients with lupus induced TLR-9 in cultured proximal tubular cells. This was prevented by CCGG-rich short oligonucleotides, specific antagonists of CpG DNA, indicating that the DNA component of immune complexes was required for TLR-9 stimulation.
These findings suggest that tubular TLR-9 activation has a pathogenetic role in tubulointerstitial inflammation and damage in experimental and human lupus nephritis, and they indicate a novel target for future therapies.
Toll样受体9（TLR-9）是一种CpG DNA受体，与狼疮中免疫细胞的激活有关。我们开展本研究以确定狼疮性肾炎中肾脏驻留细胞内TLR-9的表达是否与肾小管间质损伤的发生有关。
通过激光捕获显微切割结合实时定量逆转录聚合酶链反应，分析了处于疾病不同阶段的（NZB×NZW）F1小鼠选择性获取的肾组织中的TLR-9，并通过免疫组织化学分析了狼疮性肾炎患者的肾活检标本中的TLR-9。我们研究了狼疮患者血清中培养的近端肾小管细胞激活TLR-9的分子成分。
NZB×NZW小鼠的肾组织显示出定位于近端肾小管细胞的强烈TLR-9表达。TLR-9水平与蛋白尿和肾小管间质损伤相关，以至于一种细胞周期蛋白依赖性激酶抑制剂在减少蛋白尿和肾脏结构损伤的同时，可防止狼疮小鼠肾小管TLR-9的产生。同样，在狼疮患者的近端肾小管细胞中发现TLR-9染色增强，这与肾小管间质损伤相关。从狼疮患者血清中纯化的含DNA免疫复合物可在培养的近端肾小管细胞中诱导TLR-9。富含CCGG的短寡核苷酸（CpG DNA的特异性拮抗剂）可阻止这种情况，表明免疫复合物的DNA成分是TLR-9刺激所必需的。
这些发现表明，肾小管TLR-9激活在实验性和人类狼疮性肾炎的肾小管间质炎症和损伤中具有致病作用，并且它们指出了未来治疗的一个新靶点。
