源自於腸道之親蛋白尿毒素對於血管內皮前驅細胞功能與慢性腎病變患者臨床預後之研究

The effects of GI-related protein-bound uremic toxins on endothelial progenitor cell function and clinical outcomes in chronic kidney disease

林承叡(Cheng-Jui Lin)

指導教授 ： 劉宣良

國立臺北科技大學/工程學院/工程科技研究所/博士(2014年)

https://doi.org/10.6841/NTUT.2014.00012

摘要

心血管疾病（cardiovascular disease）長期以來一直都是導致慢性腎臟病（chronic kidney disease, CKD）患者死亡之最主要原因。然而，傳統的心血管危險因素(traditional risk factors)不能完全解釋CKD患者心血管疾病之風險。最近的研究顯示非傳統的心血管風險因素(non-traditional risk factors)，其中包括親蛋白尿毒素（protein-bound uremic toxins）- 對硫甲酚(p-cresylsulfate)與硫酸吲哚酚(indoxyl sulfate)也可能扮演重要的角色。內皮細胞（endothelial cell）功能異常被證實是造成CKD患者心血管疾病之關鍵因素。過去體外試驗顯示，對硫甲酚與硫酸吲哚酚濃度升高會增加氧化壓力及自由基，並造成血管內皮細胞和平滑肌細胞之功能異常。而血管內皮前趨細胞(endothelial progenitor cells)則被認為可幫助內皮細胞修復及促進血管新生，對硫甲酚與硫酸吲哚酚是否會導致血管內皮前趨細胞功能異常仍不清楚。
因此本論文將從體外(in vitro)至人體(in vivo)實驗探討並驗證此二尿毒素之生理毒性。細胞實驗顯示硫酸吲哚酚對於血管內皮細胞及血管內皮前趨細胞之血管新生作用(angiogenesis)有明顯抑制作用。隨著尿毒素濃度升高， 血管內皮前趨細胞之移行(migration)、細胞菌落形成 (colony forming unit) 與細胞增生(proliferation)也明顯受到抑制。然而在臨床人體研究可發現，隨著腎臟功能衰退時，人體之血管內皮細胞功能(Flow mediate dilation)則愈差，在經過多變項迴歸分析後，其也與血液中對硫甲酚、硫酸吲哚酚濃度有高度之關聯性。
此外我們也針對多項之臨床預後指標探討此二尿毒素之臨床角色。研究顯示對於慢性腎病變第三至五期患者，對硫甲酚、硫酸吲哚酚可成功預測病患之心血管事件與腎臟功能衰退；在血液透析患者，對硫甲酚則與病患之感染住院率、心血管疾病、死亡率、週邊動脈阻塞及血管通路阻塞率有高度的正相關；對於腹膜透析患者，此二尿毒素對於評估患者之心血管疾病、死亡率及腹膜透析失敗率等，也明顯達到統計學上差異。
綜合上述由體外至人體研究之結果，證實血清中對硫甲酚、硫酸吲哚酚濃度確實與臨床預後有緊密關聯性。我們推測此二毒素可能藉由抑制血管內皮前趨細胞功能，進而影響血管內皮細胞功能之完整性，最終導致慢性腎病變患者有較差之臨床預後。

關鍵字

血管內皮細胞 ； 血管內皮前趨細胞 ； 慢性腎病變 ； 親蛋白尿毒素 ； 對硫甲酚 ； 硫酸吲哚酚 ； 血液透析 ； 腹膜透析 ； 心血管疾病 ； 週邊動脈阻塞 ； 血管通路失敗

並列摘要

Cardiovascular diseases (CVD) are still the major cause of morbidity and mortality in patients with chronic kidney disease (CKD). Development of accelerated atherosclerosis involves multiple risk factors. However, traditional risk factors could not fully account for the high risk of CVD in CKD patients. Recent studies supported the idea of non-traditional risk factors, which included renal anemia, oxidative stress and uremic toxins. Protein-bound uremic toxins including indoxyl sulfate (IS) and p-cresyl sulfate (PCS) accumulated while renal function decline have been reported having adverse effect on endothelial cells (ECs) function by increasing production of oxidative stress and free radical. Endothelial dysfunction has been regarded to be the essential step resulting in CVD. However, recent studies also showed endothelial progenitor cells (EPCs) could function to restore the endothelial function damaged during coronary ischemia. It is still unclear whether IS or PCS will lead to EPCs dysfunction.
Thus, our purpose is to further investigate the pathological effects of IS and PCS from in vitro to in vivo study. Our results showed that IS had obvious negative effect on angiogenesis of human umbilical vein endothelial cells (HUVECs) and EPCs. The ability of EPCs migration, colony forming unit and proliferation were also inhibited by IS and PCS in a dose dependent manner. In addition, we also found the human endothelial function evaluated by flow mediate dilation (FMD) was significantly decreased in advanced CKD. The FMD value was negatively correlated to serum IS and PCS levels after adjusting other confounding factors.
Moreover, we also explore the effects of IS and PCS on multiple clinical outcomes in CKD. Form our research, it showed IS and PCS were capable of predicting CVD event and kidney function deterioration in patients with CKD stage 3-5. For hemodialysis patients, PCS was strongly associated with CVD event, hospitalization event and vascular access failure. Both toxins were also a valuable surrogate to evaluate the event of CVD, mortality and peritoneal dialysis (PD) failure in PD cohort.
From our results above-mentioned, it indicated that higher serum IS and PCS levels were closely related to worse clinical outcomes. We speculate that these adverse outcomes may contribute directly or indirectly to the loss of endothelial cell function owing to inhibition of EPCs function by IS or PCS.

並列關鍵字

Endothelial cell ； Endothelial progenitor cell ； Chronic kidney disease ； Protein-bound uremic toxin ； P-cresyl sulfate ； Indoxyl sulfate ； Hemodialysis ； Peritoneal dialysis ； Cardiovascular disease ； Peripheral artery disease ； Vascular access failure

參考文獻

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