Shimizu A, Masuda Y, Kitamura H, Ishizaki M, Ohashi R, Sugisaki Y, Yamanaka N
Department of Pathology, Nippon Medical School, Tokyo, Japan.
Nephron. 2000 Oct;86(2):152-60. doi: 10.1159/000045734.
Immune system mediated, particularly antibody- and complement-mediated, glomerular injury triggers glomerulonephritis (GN). To characterize complement-mediated cytotoxicity in GN, we assessed the process of mesangial cell death induced by C5b-9 attack in Thy-1 GN. Cell injury was recognized morphologically, and nuclear DNA breaks were confirmed by the DNA nick end labeling (TUNEL) method as well as DNA gel electrophoresis. Thy-1 GN was induced in rats with anti-Thy-1.1 antibody injection. Mouse IgG (administered antibody) and rat C3 were detected in all glomeruli within 5 min after antibody injection. Damaged mesangial cells with condensed as well as TUNEL-positive nuclei could be observed at 20 min and became prominent at 40-60 min. Ultrastructurally, damaged mesangial cells contained condensed apoptotic nuclei from 40 to 60 min, whereas the cytoplasm showed necrotic degeneration. This was followed by progressive lysis of both nuclei and cytoplasm. The DNA 'ladder' pattern was observed by gel electrophoresis of extracted DNA between 40 and 60 min and correlated with the increased number of TUNEL-positive damaged mesangial cells. To examine the role of complement in this form of cell death, complement depletion was induced in rats by cobra venom factor. Complement-depleted rats showed no rat C3 deposition, rare TUNEL-positive mesangial cells, rare ultrastructural degenerated mesangial cells with apoptotic nuclei and necrotic cytoplasm, and no DNA 'ladder' pattern on gel electrophoresis at 40 min, although prominent mouse IgG was seen in glomeruli. To analyze milder forms of complement injury, a low dose of the antibody was administered to rats with a normal complement level. A few TUNEL-positive mesangial cells were detected in the glomeruli which contained apoptotic nuclei and necrotic cytoplasm. Our results indicate that an apoptotic death mechanism accompanies cell necrosis in complement-mediated mesangial cell destruction in GN and that this unusual form of cell death may represent a combination of apoptosis-necrosis within the same cell. Complement injury activates a 'death program' which in turn leads to irreversible damage of mesangial cells and which may contribute to initiation and development of GN.
免疫系统介导的，特别是抗体和补体介导的肾小球损伤引发肾小球肾炎（GN）。为了表征GN中补体介导的细胞毒性，我们评估了在Thy-1 GN中C5b-9攻击诱导的系膜细胞死亡过程。通过形态学识别细胞损伤，并通过DNA缺口末端标记（TUNEL）方法以及DNA凝胶电泳确认核DNA断裂。通过注射抗Thy-1.1抗体在大鼠中诱导Thy-1 GN。在注射抗体后5分钟内，在所有肾小球中均检测到小鼠IgG（施用的抗体）和大鼠C3。在20分钟时可以观察到具有浓缩以及TUNEL阳性核的受损系膜细胞，并在40-60分钟时变得明显。在超微结构上，受损的系膜细胞在40至60分钟内含有浓缩的凋亡核，而细胞质显示坏死性变性。随后是细胞核和细胞质的进行性溶解。在40至60分钟之间通过提取的DNA的凝胶电泳观察到DNA“梯形”模式，并且与TUNEL阳性受损系膜细胞数量的增加相关。为了研究补体在这种细胞死亡形式中的作用，通过眼镜蛇毒因子在大鼠中诱导补体耗竭。补体耗竭的大鼠在40分钟时未显示大鼠C3沉积，罕见的TUNEL阳性系膜细胞，罕见的具有凋亡核和坏死细胞质的超微结构变性系膜细胞，并且在凝胶电泳上没有DNA“梯形”模式，尽管在肾小球中可见明显的小鼠IgG。为了分析较轻形式的补体损伤，将低剂量的抗体给予补体水平正常的大鼠。在含有凋亡核和坏死细胞质的肾小球中检测到一些TUNEL阳性系膜细胞。我们的结果表明，在GN中补体介导的系膜细胞破坏中，凋亡死亡机制伴随着细胞坏死，并且这种不寻常的细胞死亡形式可能代表同一细胞内凋亡 - 坏死的组合。补体损伤激活“死亡程序”，进而导致系膜细胞的不可逆损伤，这可能有助于GN的发生和发展。
