候選基因之基因多型性與Thiazolidinedione有關的周邊水腫的相關性研究

Abstract

研究背景 Thiazolidinediones (TZDs)類藥物為新一代胰島素增敏劑，包含rosiglitazone、pioglitazone；目前廣泛用於第2型糖尿病的第二線或第三線治療藥物。TZDs經由活化peroxisome proliferator-activated receptor γ (PPARγ；過氧化體增殖劑活化受器γ)而達到增加胰島素敏感度的作用。然而體液滯留(fluid retention)為TZDs類藥物最嚴重的副作用之一，通常會導致10–15%的糖尿病患者體重快速增加、產生周邊水腫或肺水腫。之前的研究指出，TZDs類藥物引發的水腫，最主要是因為腎臟管道系統對水、鈉再吸收能力增強與血管通透性增高導致；少部分因為腎臟球囊系統的腎血流量下降或腎小球濾過率下降導致。而rosiglitazone會導致小鼠腎臟中Na-K-2Cl cotransporter (SLC12A1)、sodium hydrogen exchanger 3 (NHE3)、aquaporin 2 (AQP2)與aquaporin 3 (AQP3)表現量增加。經由PPARγ基因剔除鼠證實，TZDs類藥物會經由PPARγ導致體重快速增加；且有間接證據顯示，epithelial sodium channel γ(SCNN1G)參與其中。所以在TZDs導致水腫的機制中，腎臟的作用佔了很大的因素。 研究目的 關於PPARγ在腎臟中的功能與機制，目前已被大量探討。藉由此藥物基因學的研究，看候選基因之基因多型性是否與TZDs類藥物引發的周邊水腫有任何相關性。並期望能找出較易發生周邊水腫的基因型，以減低第2型糖尿病患使用TZDs類藥物發生周邊水腫的機率，提高藥物使用的安全性。 研究方法 挑選PPARG (peroxisom proliferator-activated receptor γ)，以及在腎臟中負責水、鈉再吸收的通道、運輸蛋白：SLC12A1(Na-K-2Cl cotransporter)、NHE3 (sodium hydrogen exchanger 3)、SCNN1G (epithelial sodium channel γ)、AQP2 (aquaporin 2)、AQP3 (aquaporin 3)與AVPR2 (arginine vasopressin receptor 2)作為候選基因(candidate genes)。並從此7個基因中挑選29個tag-SNPs (tag single nucleotide polymorphisms)，利用Applied Biosystems SNPlexTM技術做為基因多型性試驗平台。於台大醫院門診時詢問就診的第2型糖尿病患，是否曾經或正在接受TZDs類藥物治療，經解說試驗內容後願意簽署同意書之受試者共328名。再根據納入與排除條件，挑選出適合的個案進行試驗。本試驗為病案組與控制組的藥物基因學研究。 結果 統計結果顯示AQP2、SCNN1G與SLC12A1的基因多型性與TZDs類藥物引發的周邊水腫有相關性。AQP2.1 (rs296766, C/T；odds ratio 2.67, p=0.0003)。SCNN1G.4 (rs4401050, C/T；odds ratio 1.88, p=0.0496)。SLC12A1.4 (rs12904216, A/G；odds ratio 1.73, p=0.0096)。其它相關性還包括女性性別因子(odds ratio 3.59, p<0.001)，顯示女性服用TZDs類藥物較易引發水腫。年齡因子 (66. 82±11.66 vs. 62.64±10.85, p=0.011)，顯示年齡越高對於TZDs類藥物引發的水腫為危險因子。 結論 女性、年齡較高對於TZDs類藥物來說，都是已知的危險因子。本藥物基因學研究提供AQP2、SCNN1G、SLC12A1基因多型性與TZDs導致水腫的危險因子，可以作為將來第2型糖尿病患選擇TZDs類藥物前的評估與考量。 關鍵字：第2型糖尿病、過氧化體增殖劑活化受器γ、硫氮烷二酮類、體液滯留、水腫、第2型水通道蛋白

Context. Thiazolidinedione (TZDs), synthetic insulin-sensitizing drugs that include rosiglitazone and pioglitazone, are highly effective in the treatment of type 2 diabetes. TZDs are believed to mediate their antidiabetic effect via activation of peroxisome proliferator-activated receptor γ (PPARγ). However, fluid retention, presented as rapid weight gain, and peripheral and pulmonary edema in 10-15% patients have emerged as the most common and serious side effects of TZDs. According to the previous studies, these drugs may cause renal fluid reabsorption directly by affecting tubular transport, renal sodium retention, and vascular hyperpermeability or indirectly by affecting renal hemodynamics or processes. Rosiglitazone increased whole kidney protein abundance of the bumetanide-sensitive Na-K-2Cl cotransporter (SLC12A1), the sodium hydrogen exchanger 3 (NHE3), the aquaporin 2 (AQP2) and aquaporin 3 (AQP3) in mice. Pioglitazone increased SCNN1G mRNA (encoding the epithelial sodium channel γ, ENaCγ) expression in inner medullary collecting ducts (IMCDs) through a PPARγ-dependent pathway. According to the evidence above, renal mechanisms play a major role in TZD-induced fluid retention. Objective. Since a direct role for PPARγ in kidney function has now been identified, the identification of its target genes will allow the initiation of genetic studies that may help identify individuals susceptible to develop edema. The objective of the present study is to investigate if genetic variations in selected candidate genes are associated with the risk of fluid retention and peripheral edema in type 2 diabetic patients treated with TZDs. Design. The genes of peroxisom proliferator-activated receptor γ(PPARG), arginine vasopressin receptor 2 (AVPR2) and the genes of major renal sodium and water transporters and channel proteins (SLC12A1, Na-K-2Cl cotransporter；NHE3, sodium hydrogen exchanger 3；SCNN1G, epithelial sodium channel γ；AQP2, aquaporin 2 and AQP3, aquaporin3) are selected into the candidate genes. The 29 tag single nucleotide polymorphisms (tag-SNPs) of these 7 candidate genes were performed by Applied Biosystems SNPlexTM assays. And genomic DNA was obtained from 328 type 2 diabetic patients receiving with TZDs since 2001. According to the inclusion and exclusion criteria, we plan to conduct a case-control study to test the association between SNPs in certain candidate genes and TZDs related peripheral edema. Results. SNPs of AQP2, SCNN1G and SLC12A1 are associated with TZD-related edema. AQP2.1 (rs296766, C/T；odds ratio 2.67, p=0.0003). The odds ratio was 2.67 for the AQP2.1 risk allele compared with the non-risk allele, corresponding to a population attributable risk fraction of 29.75%. SCNN1G.4 (rs4401050, C/T；odds ratio 1.88, p=0.0496). The odds ratio was 1.88 for the SCNN1G.4 risk allele compared with the non-risk allele, corresponding to a population attributable risk fraction of 11.49%. SLC12A1.4 (rs12904216, A/G；odds ratio 1.73, p=0.0096). The odds ratio was 1.73 for the SLC12A1.4 risk allele compared with the non-risk allele, corresponding to a population attributable risk fraction of 18.79%. Other risk factors included female gender (odds ratio 3.59, p<0.001) and age (66.82±11.66 vs. 62.64± 10.85, p=0.011). Conclusion. The female gender and age are well known clinical risk factors for TZD-induced edema. The polymorphisms in AQP2, SCNN1G and SLC12A1 genes may be used as clinically relevant pharmacogenetic risk markers for edema in patients with TZDs therapy. Key words：Type 2 diabetes, PPARγ, Thiazolidinediones (TZDs), Fluid retention, Edema, AQP2