Liu Diange, Nazneen Arifa, Taguchi Takashi, Razzaque M Shawkat
Department of Pathology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Am J Nephrol. 2008;28(4):555-68. doi: 10.1159/000115290. Epub 2008 Feb 1.
Crescentic glomerulonephritis is a rapidly progressive form of nephritis and is usually resistant to therapeutic intervention. Apoptosis plays a role in the resolution of glomerulonephritis. We investigated the effects of local kidney irradiation on the progression of experimental crescentic glomerulonephritis.
The following three experimental rat groups were generated: (1) Group I, sham-operated control (n = 12); (2) Group II, rats injected intravenously with rabbit anti-rat GBM antibody (nephrotoxic serum, NTS) (n = 23), and (3) Group III, a single low-dose irradiation of 0.5 Gy X-ray to both kidneys at days 6, 13, 20, and 27 after NTS injection (n = 55). Renal function and blood leukocyte count were examined in different groups of rats at various time points. Kidneys obtained at various time points were analyzed to determine the effects of radiation in experimental nephritis.
Radiation of the kidneys reduced the levels of blood urea nitrogen and serum creatinine compared with Group II nephritic rats of similar age (p < 0.05 or 0.001). No apparent changes in blood leukocyte counts were noted in various experimental groups. Glomerular hypercellularity, crescents, global sclerosis and tubulointerstitial damage developed gradually in Group II rats, but were decreased (p < 0.05 or 0.001) after radiation treatment. The extent of tubulointerstitial damage was also reduced, and radiation-associated histological improvements were accompanied by reduced infiltration of macrophages in the glomeruli and interstitium. The numbers of PCNA- and ED1-positive cells were reduced in the kidneys at 1 day post-irradiation, of rats irradiated at 6 and 13 days after NTS injection, compared with Group II at similar time intervals (p < 0.05). A larger numbers of TUNEL-positive cells were noted at 1 day post-irradiation in rats irradiated at 6 and 13 days after NTS injection, compared with Group II at similar time intervals (p < 0.05). Immunostaining for macrophages ED1 and TUNEL staining of serial sections of irradiated nephritic kidneys showed few ED1-positive macrophages stained for TUNEL. Overexpression of active caspases 3 and 7 was noted in irradiated kidneys, compared with the corresponding Group II rats at similar time intervals. Western blot analysis showed marked increase in active caspase 3 and active caspase 7 expression in irradiated kidneys compared with NTS injection only. A marked increase in the expression of p53 protein, which is closely related to radiation-induced apoptosis, was also observed in irradiated kidneys compared with NTS injection only.
Our study showed that renal radiation can alter acute glomerular inflammation by inducing apoptosis of intrinsic and infiltrating cells in the kidney in a rat model of crescentic glomerulonephritis. Low-dose kidney irradiation can inhibit the progression of experimental nephritis through inducing apoptosis.
新月体性肾小球肾炎是一种快速进展的肾炎形式，通常对治疗干预有抵抗性。细胞凋亡在肾小球肾炎的消退中起作用。我们研究了局部肾脏照射对实验性新月体性肾小球肾炎进展的影响。
产生以下三个实验大鼠组：（1）第一组，假手术对照组（n = 12）；（2）第二组，静脉注射兔抗大鼠肾小球基底膜抗体（肾毒性血清，NTS）的大鼠（n = 23），以及（3）第三组，在注射NTS后第6、13、20和27天对双侧肾脏进行单次0.5 Gy X射线低剂量照射（n = 55）。在不同时间点对不同组的大鼠检查肾功能和血液白细胞计数。分析在不同时间点获取的肾脏，以确定辐射对实验性肾炎的影响。
与年龄相似的第二组肾炎大鼠相比，肾脏照射降低了血尿素氮和血清肌酐水平（p < 0.05或0.001）。各实验组血液白细胞计数无明显变化。第二组大鼠中肾小球细胞增多、新月体形成、球性硬化和肾小管间质损伤逐渐发展，但在辐射治疗后有所减轻（p < 0.05或0.001）。肾小管间质损伤程度也降低，与辐射相关的组织学改善伴随着肾小球和间质中巨噬细胞浸润的减少。在注射NTS后第6天和13天接受照射的大鼠中，照射后1天肾脏中增殖细胞核抗原（PCNA）和ED1阳性细胞数量与相同时间间隔的第二组相比减少（p < 0.05）。在注射NTS后第6天和13天接受照射的大鼠中，照射后1天TUNEL阳性细胞数量与相同时间间隔的第二组相比更多（p < 0.05）。照射的肾炎肾脏连续切片的巨噬细胞ED1免疫染色和TUNEL染色显示，很少有ED1阳性巨噬细胞呈TUNEL阳性。与相同时间间隔的相应第二组大鼠相比，照射的肾脏中活性半胱天冬酶3和7过表达。蛋白质印迹分析显示，与仅注射NTS相比，照射的肾脏中活性半胱天冬酶3和活性半胱天冬酶7表达显著增加。与仅注射NTS相比，照射的肾脏中与辐射诱导的细胞凋亡密切相关的p53蛋白表达也显著增加。
我们的研究表明，在新月体性肾小球肾炎大鼠模型中，肾脏辐射可通过诱导肾脏固有细胞和浸润细胞的凋亡来改变急性肾小球炎症。低剂量肾脏照射可通过诱导细胞凋亡抑制实验性肾炎的进展。
