CXCL16在db/db糖尿病肾病小鼠肾组织中的表达

Expression of CXCL16 in the kidney of diabetic db/db mice

目的:了解在糖尿病肾病(DN)发生发展过程中,CXCL16在db/db小鼠肾脏中的表达变化,并对其与DN的相关性进行初步探讨。方法:选取分别代表DN不同发展阶段的4、8、12、16和20周龄的db/db小鼠和同龄db/m小鼠各6只;取左肾的一半用于提取总RNA;右肾用于制作冰冻切片、石蜡切片、电镜标本等;利用半定量RT-PCR的方法分析各组小鼠肾脏中CXCL16 mRNA相对表达水平,以免疫组化的方法分析CXCL16蛋白在各组小鼠肾组织中的表达和分布情况;同时测定各组小鼠的体重、血糖、血三酰甘油、血胆固醇和24h尿白蛋白排泄量,分析各组小鼠的肾脏组织病理情况以了解小鼠DN的发生发展情况。结果:(1)与同龄的db/m小鼠相比,4周龄的db/db小鼠的体重有所增加,但血糖、血三酰甘油、血胆固醇、24h尿白蛋白排泄量均无明显差异,肾脏组织病理分析也无明显变化,说明4周龄的db/db小鼠尚未发生糖尿病;但8周龄的db/db小鼠的血糖、24h尿白蛋白排泄量均已有明显升高,且肾组织中也已出现肾小球肥大、系膜区扩张、基膜增厚等DN病理改变,说明8周龄的db/db小鼠已发生了DN,但从各方面的情况来看,8周龄db/db小鼠的DN仍较轻,可代表DN早期的情况;自8周龄以后,db/db小鼠的血糖、血三酰甘油、血胆固醇、尿白蛋白排泄量以及肾小球肥大、系膜区扩张、基膜增厚等情况随着鼠龄的增长而不断的增加,说明db/db小鼠的DN不断进展。(2)与同龄的db/m小鼠相比,CXCL16在4周龄的db/db小鼠肾脏中的表达并没有明显变化;但8周龄db/db小鼠肾脏中CXCL16的表达水平已有所增加。此后,随着鼠龄的增加,DN的进展,CXCL16的表达水平逐渐增加。(3)在成年正常小鼠,CXCL16主要分布于小鼠肾脏髓质的小管中,相对来说在肾脏皮质中的分布较少;在DN小鼠,分布在肾小管和小球中的CXCL16均有明显增加;且肾小球CXCL16的表达增加主要发生在足细胞的位置。(4)CXCL16在幼年小鼠(指4周龄的db/m和db/db小鼠)肾脏中的表达分布与成年小鼠(指8周龄以上)亦存在一些差异,这可能提示CXCL16与小鼠肾脏的正常生长发育有关。结论:db/db小鼠肾脏中CXCL16的表达随DN的发生发展而增高,至少在时间上与DN具有相关性,提示CXCL16可能参与DN的病理过程。

Objective：To investigate the renal expression of CXCL16 in db/db mice, a model of type 2 diabetic nephropathy（DN）, during the development of DN. Methodology：Kidney samples were obtained from db/db mice and their db/m littermates at the age of 4,8,12,16 and 20 weeks. The expression of CXCL16 was assessed by RT-PCR and immunohistocbemistty, and then correlated with biochemical and histological indices of kidney injury. Results： No significant difference of CXCL16 expression was found in the kidney of db/db mice as compared with the control db/m mice at the age of 4 weeks, a time when all biochemical and histological indices indicated that the db/db mice were in pre-diabetic condition. However, with the development of obesity, hyperglycemia and proteinuria, the expression of CXCL16 in the kidney of db/db mice increased. CXCL16 protein was distributed mainly in the renal distal tubule and in the glomerular podocytes to a less extent. Besides, different distribution of CXCL16 was also found between young mice（4-week-old db/m and db/db mice） and adult mice（db/m mice of 8-week-old and older than 8 weeks）, which may suggest that CXCLI6 might have some thing to do with the growth and development of kidney. Conclusion： Renal CXCLI6 expression increased with the development of DN suggests that CXCL16 might involve in the initiation and development of DN in db/db mice.