尿中血管收縮素轉化酶2及其活性與犬貓慢性腎病的關聯

Abstract

研究背景： 腎素-血管收縮素-醛固酮系統 (RAAS)的過度活化長久以來被認為是導致慢性腎病惡化的重要因子，然而隨著近年發現新的血管收縮素轉化酶2 (ACE2)和新興的RAAS成員，為此系統的認知開啟了新的觀點。根據研究文獻指出，位於細胞膜上的ACE2能將血管收縮素II (Ang II)催化為具有生物活性的血管收縮素 (1-7)，其可產生拮抗Ang II所造成的負面效應而達到腎臟保護的功能。另一方面，在實驗上發現在腎臟疾病的病患或動物模型中，尿液中的ACE2會顯著地增加，其可能作為反應腎臟損傷及研究腎臟RAAS的潛在生物標記。然而其在小動物獸醫領域上目前尚未尋得相關研究。 研究目的： 本研究的目的在於評估慢性腎病的犬貓尿液中ACE2的量和活性是否會在腎病的犬貓有顯著改變以及其與相關臨床病理參數的關聯性，且在慢性腎病不同次分組中是否亦有不同，以及這些生物標記是否能作為犬貓腎臟疾病的預後指標。 研究對象： 本實驗總共在臨床上收集40隻狗和81隻貓。包含18隻健康的犬隻和22隻患有慢性腎病的犬隻以及24隻健康的貓和57隻患有慢性腎病的貓。 實驗方法： 利用商業套組酵素免疫吸附檢定和螢光檢測分別測量犬貓尿液中的ACE2濃度與活性，並將所測得之尿液ACE2濃度和活性皆進一步除以尿液中肌肝酸濃度作為校正，分別以UALCR和UAACR作為表示。 實驗結果： UALCR在無論犬或貓的慢性腎病組(犬的中位數和四分位距為5.124 [3.516-11.078] x 10-6;貓的中位數和四分位距為3.759 [2.100-5.145] x 10-6)中皆顯著高於健康控制組(犬:0.844 [0.638-1.574] x 10-6; 貓:0.894 [0.610-1.076] x 10-6)(P值皆< .001)，且UALCR隨著慢性腎病的嚴重程度上升而增加；然而，相較於健康控制組，慢性腎病組的犬隻UAACR有顯著地增加(控制組: 0.346 [0.155-0.452] pmol/min/mg;慢性腎病組: 1.343 [0.725-1.772] pmol/min/mg, P值< .001)而慢性腎病組的貓其UAACR與健康控制組則無顯著差異(控制組: 1.606 [0.993-4.585] pmol/min/mg;慢性腎病組: 1.792 [0.512-3.099] pmol/min/mg, P值= .469)。 患有蛋白尿的慢性腎病犬貓，其UALCR(犬:5.998 [4.175-12.333] x 10-6; 貓:7.620 [4.563-10.674] x 10-6)和UAACR(犬:1.410 [1.016-1.792] pmol/min/mg;貓: 3.321 [1.346-8.164] pmol/min/mg)皆顯著高於無蛋白尿之慢性腎病犬貓(UALCR在犬為3.852 [2.216-4.657] x 10-6;在貓為2.992 [1.918-4.608] x 10-6/UAACR在犬為0.562 [0.259-1.357] pmol/min/mg; 在貓為1.172[0.451-2.304] pmol/min/mg)，而高血壓組和無高血壓組在不論UALCR和UAACR之間都無顯著差異。 在慢性腎病貓追蹤180天內有腎臟惡化相較無腎臟惡化的貓有顯著較高的UALCR (腎臟惡化組:4.897 [4.033-9.137] x 10-6;無腎臟惡化組:2.719 [2.100-4.848] x 10-6,P值= .021)，且UALCR在預測慢性腎病貓追蹤180天內有無腎臟惡化上有顯著意義AUROC (P = .021) 重要結論： 總結來說在犬貓中RAAS的改變可反應腎功能一定程度的下降，尤其是在患有蛋白尿的慢性腎病犬貓。另外在慢性腎病的貓咪中，較高的UALCR意味著腎臟疾病有較快的惡化速度。

Background Over-activation of the renin-angiotensin-aldosterone system (RAAS) has been recognized as an important progressive factor in renal disease for a long time. In recent decades new angiotensin-converting enzyme 2 (ACE2) and others emerging RAAS peptides were discovered, expanding our knowledge of this system. Based on research, membrane-bound ACE2 can catalyze Ang II into Ang (1-7), which has biological action against the negative effect caused by Ang II. On the other hand, the increased urinary ACE2 in humans or animal models with renal disease was found, suggesting that urinary ACE2 could reflect renal injury and be a tool for investigating intrarenal RAAS. However, study of urinary ACE2 in veterinary medicine was limited. Aim Thus, our aim of the study was: 1) to evaluate the alternation of urinary ACE2 level and activity in canine and feline CKD, and to determine uACE2 between various subgroups of CKD furthermore 2) to investigate the correlation between urinary ACE2 and clinicopathologic parameters. 3) to assess the predictive role of urinary ACE2 for renal progression Research object Totally 40 dogs and 81 cats were enrolled in this study, including 18 healthy dogs and 22 CKD dogs, and 24 healthy cats and 57 CKD cats. Methods Urinary ACE2 level and activity were measured by commercial ELISA kit and fluorometric assay kit, respectively. Urinary ACE2 level and activity were further adjusted as urinary ACE2 level-to-creatinine ratio (UALCR) and urinary ACE2 activity-to-creatinine ratio (UAACR), respectively. Results UALCR was significantly higher in canine and feline CKD groups (canine: 5.124 [3.516-11.078] x 10-6; feline: 3.759 [2.100-5.145] x 10-6) than those in the health groups (canine: 0.844 [0.638-1.574] x 10-6; feline: 0.894 [0.610-1.076] x 10-6), and both P value < .001, and it increased as renal function declined. Compared to the control group, CKD dogs had higher UAACR (control group: 0.346 [0.155-0.452] pmol/min/mg; CKD group: 1.343 [0.725-1.772] pmol/min/mg, P value< .001)) whereas CKD cats had indifferent UAACR (control group: 1.606 [0.993-4.585] pmol/min/mg; CKD group: 1.792 [0.512-3.099] pmol/min/mg, P value = .469) Canine and feline CKD complicated with proteinuria had significantly higher UALCR (canine:5.998 [4.175-12.333] x 10-6; feline:7.620 [4.563-10.674] x 10-6) and UAACR (canine:1.410 [1.016-1.792] pmol/min/mg; feline:3.321 [1.346-8.164] pmol/min/mg) than those without proteinuria (UALCR: canine:3.852 [2.216-4.657] x 10-6; feline:2.992 [1.918-4.608] x 10-6/UAACR:canine:0.562 [0.259-1.357] pmol/min/mg; feline:1.172[0.451-2.304] pmol/min/mg), and there was no statistical difference between those with and without hypertension. CKD cats with renal progression within 180 days had significantly higher UALCR than those in the non-progression group (progression group:4.897 [4.033-9.137] x 10-6; non-progression group: 2.719 [2.100-4.848] x 10-6, P = .021). Also, UALCR had a significant AUROC to predict renal progression in cats with CKD (P = .021). Conclusion RAAS status in urine was altered as the renal function declined in dogs and cats, especially in those with proteinuria. Furthermore, higher UALCR implies a faster progression in feline CKD.