Masum M A, Ichii O, ELewa Y H A, Kon Y
1 Laboratory of Anatomy, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
2 Department of Anatomy, Histology and Physiology, Faculty of Animal Science and Veterinary Medicine, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh.
Lupus. 2019 Mar;28(3):324-333. doi: 10.1177/0961203319828518. Epub 2019 Feb 10.
Toll-like receptor (Tlr) 9 is capable of recognizing exogenous and/or endogenous nucleic acids and plays a crucial role in innate and adaptive immunity. Recently, we showed that Tlr9 is overexpressed in podocytes, a component of the blood-urine barrier (BUB), in glomeruli of autoimmune glomerulonephritis (AGN) model mice. This study investigated the activation of peritubular capillary (PTC) endothelial cells (ECs), a component of the BUB in the tubulointerstitium, through overexpressing Tlr9, and the subsequent development of tubulointerstitial lesions (TILs) in AGN model mice.
Lupus-prone BXSB/MpJ-Yaa (Yaa) and BXSB/MpJ (BXSB) mice were used as an AGN model and control, respectively. In addition to histopathological and ultrastructural techniques, protein and mRNA levels were also evaluated. The relationship between Tlr9 and TIL indices was analyzed by statistical correlation analysis.
Yaa mice developed TILs and showed strong Tlr9 mRNA expression in PTC ECs at 24 weeks (wks) of age. However, BXSB mice showed no TIL but faint expression of Tlr9 mRNA at 8 and 24 wks of age. Tlr9 protein localization on PTC was almost absent in BXSB mice at both ages but intense expression was found in Yaa mice only at 24 wks of age. Relative mRNA expression of Tlr9 and its putative downstream cytokines, including interleukin 1 beta ( Il1b), Il6, interferon gamma ( Ifng), and tumor necrosis factor alpha ( Tnf) was markedly increased in isolated tubulointerstitium from Yaa mice at 24 wks of age. Furthermore, electron microscopy examination revealed PTC injury and TIL in Yaa mice at 24 wks. The expression level of Tlr9 in the tubulointerstitium was correlated with inflammatory cells in TILs, injured PTC, Ilb and Tnf expression, and damaged tubules ( P < 0.05 and 0.01).
Induced expression of Tlr9 in ECs correlates with PTC injury and the development of TILs in lupus-prone AGN model mice.
Toll样受体9（Tlr9）能够识别外源性和/或内源性核酸，在固有免疫和适应性免疫中发挥关键作用。最近，我们发现Tlr9在自身免疫性肾小球肾炎（AGN）模型小鼠肾小球中足细胞（血-尿屏障的组成部分）中过表达。本研究通过过表达Tlr9来研究肾小管间质中血-尿屏障组成部分的肾小管周围毛细血管（PTC）内皮细胞（ECs）的激活情况，以及AGN模型小鼠随后肾小管间质病变（TILs）的发展。
将易患狼疮的BXSB/MpJ-Yaa（Yaa）小鼠和BXSB/MpJ（BXSB）小鼠分别用作AGN模型和对照。除了组织病理学和超微结构技术外，还评估了蛋白质和mRNA水平。通过统计相关性分析分析Tlr9与TIL指标之间的关系。
Yaa小鼠在24周龄时出现TILs，并且在PTC ECs中显示出强烈的Tlr9 mRNA表达。然而，BXSB小鼠在8周和24周龄时未出现TIL，但Tlr9 mRNA表达微弱。在两个年龄段，BXSB小鼠PTC上几乎不存在Tlr9蛋白定位，但仅在24周龄的Yaa小鼠中发现强烈表达。在24周龄的Yaa小鼠分离的肾小管间质中，Tlr9及其假定的下游细胞因子，包括白细胞介素1β（Il1b）、Il6、干扰素γ（Ifng）和肿瘤坏死因子α（Tnf）的相对mRNA表达明显增加。此外，电子显微镜检查显示24周龄的Yaa小鼠存在PTC损伤和TIL。肾小管间质中Tlr9的表达水平与TIL中的炎性细胞、受损的PTC、Ilb和Tnf表达以及受损的肾小管相关（P < 0.05和0.01）。
ECs中Tlr9的诱导表达与易患狼疮的AGN模型小鼠中PTC损伤和TILs的发展相关。
