肥大细胞参与蛋白负荷肾病大鼠肾间质的纤维化

目的 观察肥大细胞（MC）在蛋白负荷肾病肾间质纤维化大鼠模型肾脏的分布并探讨其与蛋白尿所致肾间质纤维化、肾间质转化生长因子β1（TGF-β1）及干细胞因子（SCF）表达的关系。 方法 60只SD大鼠行右肾全切术后，模型组腹腔注射牛血清白蛋白（BSA）复制蛋白负荷肾病大鼠的模型（n=30），对照组腹腔注射生理盐水（n=30），分别于模型成功后第3、7和11周，随机处死10只大鼠，检测尿蛋白和血生化指标。采用甲苯胺蓝组织化学和糜蛋白酶（chymase）免疫组化的方法观察肥大细胞在肾脏的浸润。采用免疫组化法检测TGF-β1、SCF在肾组织的表达，并分析它们之间及与蛋白尿所致肾间质纤维化的相关性。 结果 模型组大鼠随着BSA注射量的增加, 尿蛋白量（24 h）增加，第7周达到高峰(199.1±98.4) mg], 以后开始下降，第11周为(133.7±67.8) mg。在模型组大鼠的肾皮质、髓质均可见甲苯胺蓝染色阳性及chymase阳性的肥大细胞, 以间质纤维化区域最为多见。随着肾间质纤维化的加重, 肥大细胞数目增多，各时间点模型组大鼠与对照组差异均有统计学意义（P < 0.05）。TGF-β1及SCF主要在肾小管、间质、部分系膜细胞及壁层上皮细胞表达，随时间的延长表达量增加，各时间点模型组大鼠与对照组差异均有统计学意义（P < 0.05）。肥大细胞的数量与肾间质纤维化的程度、TGF-β1和SCF的表达均呈正相关(r分别为0.722、0.521、0.916, 均P < 0.01)。 结论 肥大细胞浸润与蛋白负荷肾病大鼠肾间质纤维化程度密切相关。蛋白尿可能通过SCF介导肥大细胞到肾脏，释放chymase，促进肾组织TGF-β1表达，介导蛋白尿所致的肾间质纤维化。

Mast cell infiltration is involved in renal interstitial fibrosis of rat models with protein overload nephropathy

Objective To investigate the correlation of infiltration of mast cells in kidney with renal interstitial fibrosis, expression of TGF-β1 and stem eel] factor (SCF) in rat models withprotein-overload nephropathy. Methods Sixty uninephrectomized SD rats were randomly divided into model group intraperitoneal injections of bovine serum albumin (BSA)] and control group (intraperitoneal injections of equal volume of saline). Ten rats from both groups were sacrificed respectively at week 3, 7 and 11 after injection. 24 h urinary protein and serum biochemistry of these SD rats at the time of sacrifice were measured. The intensity of mast cell infiltration was examined by toluidine blue (TB) staining and immunohistochemistry using a monoclonal anti-MC chymase antibody. The expression of TGF-β1 and SCF was detected byimmunohistochemistry, using a monoclonal mouse anti-rat TGF-β1 antibody and a polyclonal rabbstanti-rat SCF antibody. Results Severe proteinuria was induced in the rats by BSA injectionpeaked at week 7 (199.1±98.4) mg/d] after the BSA injection and gradually decreased until week11 (133.7±67.8) mg/d]. Renal injury was accompanied with chymase-postitive and TB-postitive mast cell infiltration, in close proximity to areas of interstitial fibrosis. With aggravation oflesions degree, the number of mast cells increased,the difference between the modal rats and control rats was significant (P<0.05). Immunostainahle expression of SCIF and TGF-β1 was detected in tubular as well as interstitial cells, and increased with the BSA injection. The difference between the model rats and control rats was significant (P<0.05). Mast cells were positively correlated with interstitial fibrosis (r=0.772, P<0.01), expression of TGF-β1 (r=0.521, P<0.01) and SCF(r=0.916,P<0.01). Conclusions Increased infiltration of mast cells is involved in interstitial fibrosis of rats with protein-overload nephropathy. Proteinuria may attract mast cells to kidney by chemot actions of SCF,and mast cells may contribute to the development of renal fibrosis by secreting chymase and increasing expression of TGF-β1.