2012-08-012024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/660513摘要：慢性腎病不僅是身體健康的問題，其治療的花費更是社會經濟的巨大負擔。雖然慢性腎病的病因各有不同，在病理檢查中幾乎都會觀察到腎臟間質中肌肉纖維母細胞與發炎細胞增加、腎小管萎縮、與腎小管周邊微血管減少，這些變化會逐步造成腎臟纖維化、功能喪失以至末期腎病。台灣末期腎病患者的盛行率與發生率居世界前三位，因此防治慢性腎病的惡化對我們尤其重要。慢性腎病的治療包括糖尿病患者的嚴格血糖控制、高血壓患者的嚴格血壓控制、利用腎素-血管張力素-醛固酮抑制劑來控制蛋白尿、以及限制蛋白的飲食治療。雖然這些治療已大為改善慢性腎病的惡化，但近二十年來並沒有更進一步的發展。為了改善此一窘境並增加治療的效果，進一步了解慢性腎病惡化的病理機轉並找出更具專一性的惡化因子是目前的當務之急。我們最近證實在慢性纖維化的腎臟中，肌肉纖維母細胞的主要來源是血管的周邊細胞(pericytes)。此一發現將促使整個腎臟科學界對於腎臟纖維化的研究從腎小管上皮細胞轉分化轉移至血管病生理的研究，其中包括腎小管周邊血管內皮細胞與血管周邊細胞的交互作用對於腎臟纖維化的影響。我們最近已證實在慢性腎病的動物模式中，阻斷血管內皮細胞或血管周邊細胞的活化都可以減少肌肉纖維母細胞增生、防止間質微血管減少、及改善腎臟纖維化。過去的文獻已證實在胚胎時期或腫瘤的血管生長時，血管周邊細胞會製造血管內皮細胞生長因子(VEGF)與第一型血管生成素(angiopoietin1)，以刺激血管新生。然而我們在單側輸尿管阻塞與缺血再灌注的慢性腎病動物模式中發現這些傷害不僅會造成血管周邊細胞轉分化成肌肉纖維母細胞，也同時造成腎臟內有關血管滋養的生長因子轉變成以異構體188 (VEGF188)為主的血管內皮細胞生長因子，而第二型血管生成素(angiopoietin 2)也逐漸增加，最終變成以第二型血管生成素為主。而且我們也發現慢性腎病患者血漿中第二型血管生成素濃度隨慢性腎病惡化而升高，且與用脈波速度(pulse wave velocity)測量的動脈硬化程度呈正相關。雖然我們已證實抑制血管內皮細胞生長因子受體傳導的訊息可以防止腎臟間質的纖維化，但這並非是絕對安全的治療，因為有研究指出血管內皮細胞生長因子異構體164對於維持正常的腎絲球功能可能是必須的。因此我們提出的假說是慢性腎病所誘發的血管內皮細胞生長因子異構體轉變對於腎臟的微血液循環是有害的，可能因此促進腎臟的炎性細胞浸潤與纖維化；而第二型血管生成素在腎臟與血液循環中的增加也可能造成血管內皮細胞的傷害與炎性細胞浸潤，不僅促進腎臟纖維化也造成動脈的硬化。為證實這些假說，我們將先利用本實驗室常用的慢性腎病動物模式，包括了單側輸尿管阻塞、缺血再灌注、及六分之五腎臟切除等模式來研究是否所有的模式都表現出相同的血管滋養生長因子異常。然後我們將利用基因改造鼠在腎小管細胞或其他腎臟細胞表現或剔除血管內皮細胞生長因子異構體188與第二型血管生成素以研究這些血管滋養生長因子的異常表現對於腎臟纖維化、發炎細胞浸潤、與血管病理與生理的影響。初步的研究顯示這些計畫是可行，而且領先世界上關於慢性腎病與相關的心血管疾病研究。我們相信本研究的結果，一定可以找出進一步治療慢性腎病與相關心血管疾病的標的。<br> Abstract: Chronic kidney disease (CKD) is not only an issue of individual and public health but also ahuge socioeconomic burden. Although etiology is different in patients, the pathology of CKD ischaracterized by expanded population of interstitial myofibroblasts and inflammatory cells,tubular atrophy, and peritubular capillary rarefaction which lead to progressive kidney fibrosisand finally end-stage renal disease (ESRD). Both prevalence and incidence of ESRD in needof long-term dialysis therapy or kidney transplantation in Taiwan are ranked number one andthree in the world respectively. In addition to blocking renin-angiotensin-aldosterone (RAA)system, no major advance was achieved in CKD treatment in recent 2 decades. It will be crucialto advance our knowledge in the novel pathogenesis of CKD and its comorbidities before wecan make further progress in developing treatment of efficacy. We have recently identified thatmicrovascular pericytes are the origin of myofibroblasts in fibrotic kidney. The fact thatpericytes are a major source of myofibroblasts serves to readjust the focus of fibrosis research toareas that are potentially of more importance in the CKD progression including the crosstalkbetween pericytes and endothelial cells of the peritubular capillaries. This hypothesis has beenrecently proved by targeting endothelium-pericyte cross talk which could attenuatemicrovascular rarefaction and fibrosis using blockade of either vascular endothelial cell growthfactor (VEGF) receptor or platelet-derived growth factor receptor β on endothelial cells andpericytes respectively. Fibrogenic injuries not only induce pericyte-myofibroblast transition butalso switch VEGF isoforms to VEGF188 and upregulate angiopoietin 2 (Angpt2) in injuredkidney. Plasma level of Angpt2 increases in both patients and mice with CKD, and correlateswith arterial stiffness assessed by pulse wave velocity. Although targeting all VEGF signallingprevents interstitial fibrotic consequences, it is not a 100% safe treatment because VEGF164isoform is indispensable for normal glomerular physiology. We hence propose our firsthypothesis that VEGF isoform switch is detrimental for microcirculation and predisposes tointerstitial inflammation and fibrosis. Furthermore upregulated Angpt2 in kidney and circulationmay not only block physiological angiopoietin 1 (Angpt1)/Tie2-favored signalling but alsocontribute to increased interstitial inflammation in kidney and arteries thereby destabilizeendothelial cells and increase arterial stiffness by collagen production locally. Therefore oursecond hypothesis is the detrimental role of increased Angpt2 in kidney and vasculature. Firstof all we will study the dysregulation of VEGF and Angpt in mouse CKD models in ourlaboratory including unilateral ureteral obstruction, ischemia-reperfusion, and 5/6 subtotalnephrectomy. To study the role of VEGF188- or Angpt2-favored signalling in kidney fibrosisand vascular pathology in mouse CKD models, we will selectively induce or knock outVEGF188 or Angpt2 in renal tubular epithelial cells. To do these we will need to apply Tet-onand Cre-loxP systems to overexpress or knock out VEGF188 or Angpt2 in Pax8+ tubularepithelial cells. Hence mice with inducible potentials of overexpression or knockout inVEGF188 and Angpt2 will be developed in this study first, then we will check their specific rolein mouse CKD models regarding inflammation, microvascular rarefaction, and fibrosis ofkidneys, arterial stiffness, and the surrogate markers of aortic stiffness including increased localinflammation and collagen production in vascular smooth muscle cells, decreased relaxationfactors and survival in endothelial cells. We believe this study will advance the development ofnovel treatments to attenuate the arterial stiffness, microvascular rarefaction, and kidney fibrosisin CKD patients thorough targeting VEGF188 and Angpt2.慢性腎病血管周邊細胞血管內皮細胞生長因子血管生成素動脈硬化Chronic kidney diseasepericytevascular endothelial cell growth factorangiopoietinarterial stiffness