c-Kit信号通路对输尿管功能性梗阻疾病中ICC细胞功能的影响及机制研究

Functional ureteral obstruction is one of the most common cause of congenital hydroureter. It has been suggested that this disease could be initiated by the absence of ICCs. Moreover, there has been much debate about ICCs. Until now,some researcher suggest that the pacemaker cells of upper urinary tract is ICC, but some researcher hold that is atypical smooth muscle cells(ASMCs). It has been reported that blocking c-Kit signal pathway can induce ICC transform to ASMC. In our previous research, we also found ICCs and ASMCs have very close relationship in renal pelvis.We hypothesis that atypical smooth muscle cells maybe the subtype of ICCs..Based on the important function of ICCs in functional ureteral obstruction and the key role of c-kit signal pathway in function of ICCs,in this study,firstly we plan to detect the similarities and differences of ICCs, ASMCs and SMCs under normal and pathological conditions. Secondly, in vitro and vivo, verify c-kit signal pathway can induce the differences of those three cells. Thirdly, illuminate the specific molecular mechanisms of c-kit signal pathway which induce ICCs transform to ASMCs and SMCs. Through the experimental study above, we hope we can enrich the pacemaking theory of upper urinary tract and provide new method or novel therapy target for the treatment of functional ureteral obstruction.

输尿管功能性梗阻疾病是以肾积水、输尿管扩张为临床特征的上尿路动力性疾病，其病变部位蠕动功能丧失，从而引起梗阻症状，是新生儿先天性肾积水常见病因之一。大量文献报道其病因与ICC（interstitial cells of cajal）分布减少密切相关。ICC是胃肠道起搏细胞，但上尿路起搏细胞是ICC还是非典型平滑肌细胞目前存在争论。多项研究发现，c-Kit信号通路阻滞后ICC会向平滑肌细胞转化而非凋亡，且先出现一种中间体细胞。结合本课题组前期发现我们认为功能性梗阻中ICC减少与c-Kit信号通路受到干扰有关；肾盂非典型平滑肌细胞极有可能是由ICC向平滑肌细胞转化的中间体。本项目拟以ICC为研究对象，以c-Kit信号通路为切入点，深入研究c-Kit信号通路对于肾盂、输尿管ICC的影响及相关分子机制，一方面为临床提供可能的药物作用靶位和治疗手段，一方面为上尿路兴奋性起源细胞的界定提供实验依据。

输尿管功能性梗阻疾病是以肾积水、输尿管扩张为临床特征的上尿路动力性疾病，其病变部位蠕动功能丧失，从而引起梗阻症状，是新生儿先天性肾积水常见病因之一。大量文献报道其病因与ICC（interstitial cells of cajal）分布减少密切相关。ICC是胃肠道起搏细胞，但上尿路起搏细胞是ICC还是非典型平滑肌细胞目前存在争论。因此本项目主要针对输尿管功能性梗阻疾病的病因及上尿路兴奋起源来展开。我们检测了ICC细胞在输尿管、肾盂中的表达情况，发现ICC细胞在肾盂中呈网络状分布，主要分布在粘膜下层。在输尿管中的粘膜下层和肌层都有表达，它们可能承担了输尿管蠕动过程中的不同功能。我们对培养的平滑肌细胞、非典型平滑肌细胞和ICC细胞进行鉴定，结果发现ICC细胞c-kit、Vimentin双标阳性，非典型平滑肌细胞c-kit及SMA双标阳性。这说明非典型平滑肌细胞可能和ICC细胞存在关系，遗憾的是膜片钳检测没有检测出ICC细胞和非典型平滑肌细胞的电流特点。接下来我们收集了30例肾盂输尿管连接部狭窄的患者标本，进行免疫荧光和Western blot检测，并和对照组进行比较，结果发现UPJO患者其肾盂输尿管连接部c-kit表达量明显低于正常组；而在输尿管组织则无明显的统计学差异；接下来对平滑肌细胞c-Kit信号通路进行干扰后，平滑肌细胞出现ICC细胞表型。如果外部电流刺激可以引起输尿管的蠕动变化，则对于输尿管梗阻性疾病来说，是一个非常好的解决方案，于是本项目增加了电流刺激输尿管蠕动的实验内容，结果发现单依靠电极直接对输尿管及肾盂粘膜及肌肉进行刺激很难打破输尿管自身蠕动频率和走向。综上，结合本实验所有研究结果，我们认为功能性梗阻疾病中ICC减少与c-Kit信号通路受到干扰有关。肾盂非典型平滑肌细胞极有可能是由ICC向平滑肌细胞转化的中间体。上尿路兴奋性起源是由肾盂肾盏连接部发起，但具体是ICC细胞还是非典型平滑肌细胞还不能确定。对于肾盂输尿管连接部狭窄的患者来说，ICC细胞的发育障碍可能是一个重要病因。