血液透析患者的同半胱胺酸、相關的B-維生素和穀胱甘肽與發炎反應和氧化壓力之關係

Homocysteine, the related B-Vitamins and Glutathione in relation to Inflammation and Oxidative Stress in Hemodialysis Patients

葉恩菱(EN-LING YEH)

指導教授 ： 黃怡嘉 教授

中山醫學大學/健康管理學院/營養學系/博士(2020年)

https://doi.org/10.6834/CSMU202000010

摘要

根據台灣衛生福利部2019年的報告，腎炎、腎病症候群和腎病變是台灣死亡原因的第九位。慢性腎臟病和血液透析病人長期處在持續性輕微發炎狀態，可能與病人有較差的臨床結果和較高死亡率有關。慢性腎臟病和血液透析病人常見有高同半胱胺酸血症及低維生素B-6營養狀況。雖然高同半胱胺酸血症會增加氧化壓力而啟動發炎反應，維生素B-6的活化型態(磷酸吡哆醛)參與同半胱胺酸的轉硫作用，且是發炎反應過程中的細胞激素和其他多胜肽調節物的輔酶，但是同半胱胺酸及維生素B-6營養狀況是獨立還是聯合影響慢性腎臟病及血液透析病人的發炎狀態尚未被探討。因此，以橫斷面研究模式探討慢性腎臟病及血液透析治療病人的血漿維生素B-6和高同半胱胺酸濃度與發炎反應指標的關係。結果發現，68位慢性腎臟病和68位血液透析病人(n = 136)的血漿磷酸吡哆醛與C-反應蛋白濃度呈現顯著負相關(partial γs= - 0.21, p < 0.05)；血漿吡哆醛與介白素-10的濃度呈現顯著負相關(partial γs= - 0.24, p < 0.05)；血漿磷酸吡哆醛+吡哆醛與C-反應蛋白濃度呈現顯著負相關(partial γs= - 0.20, p < 0.05)，但與介白素-1β呈現顯著正相關(partial γs= 0.22, p < 0.05)；進一步調整血漿同半胱胺酸濃度後仍具有一致的結果。相反的，血漿同半胱胺酸濃度與發炎反應指標無顯著相關性。當慢性腎臟病病人處在維生素B-6的營養素不足時，可能會增加發炎反應。

雖然慢性腎臟病和血液透析病人的同半胱胺酸濃度與發炎反應無顯著相關性，但血液透析病人於透析前皆處於高同半胱胺酸血症的狀態。血液透析治療雖然是末期腎臟病病人接受腎移植前的最佳治療方式，但透析過程，尤其是足量透析，可能增加水溶性維生素的流失，進而影響同半胱胺酸的代謝。因此，以橫斷面研究模式觀察末期腎臟病病人接受足量和不足量血液透析治療時，其透析前和透析後的B-維生素(葉酸、維生素B-6和維生素B-12)營養狀態與同半胱胺酸濃度變化的關係。結果顯示，所有血液透析病人於透析治療後的血漿同半胱胺酸、半胱胺酸、葉酸、磷酸吡哆醛和維生素B-12濃度均顯著降低，但透析治療後仍有一半病人有高同半胱胺酸血症。足量透析組(Kt/V: 1.21 - 1.83, n = 48)和不足量透析組(Kt/V: 0.9 - 1.2, n = 20)於透析前或透析後的血漿維生素B-12與同半胱胺酸濃度均呈現顯著負相關，但葉酸和磷酸吡哆醛與同半胱胺酸濃度無相關性。雖然葉酸、維生素B-6及B-12皆參與同半胱胺酸代謝，但只有維生素B-12濃度與同半胱胺酸濃度變化有關，確切的原因需要進一步探討。

雖然血液透析治療後可降低同半胱胺酸濃度但也同時移除半胱胺酸。半胱胺酸是合成穀胱甘肽的限速物質，可能會影響血液透析病人的抗氧化能力。因此，以橫斷面研究模式探討接受血液透析治療病人的還原態及氧化態穀胱甘肽及其氧化還原電位是否與半胱胺酸濃度或氧化壓力變化有相關性。結果顯示，病人於血液透析治療後的血漿半胱胺酸、還原態和氧化態穀胱甘肽濃度皆較透析前顯著降低，但是透析後的血漿丙二醛濃度、還原態穀胱甘肽/氧化態穀胱甘肽比值和穀胱甘肽氧化還原電位狀態皆近乎不變。透析後的血漿還原態和氧化態穀胱甘肽與血漿丙二醛濃度呈現正相關，穀胱甘肽氧化還原電位與血漿丙二醛濃度呈負相關。但是透析前後的血漿還原態和氧化態穀胱甘肽、還原態穀胱甘肽/氧化態穀胱甘肽的比值和穀胱甘肽氧化還原電位數值均與血漿半胱胺酸濃度皆無顯著相關性。血液透析病人似乎需要較高濃度的穀胱甘肽以應付體內的氧化壓力。

總結上述三個橫斷面研究，建議慢性腎臟病和血液透析病人須維持足夠的維生素B-6營養狀態以降低發炎反應；血液透析病人需注意其透析前後的維生素B-12濃度以降低高同半胱胺酸濃度的影響；此外血液透析病人可能有較高的穀胱甘肽需求，以因應血液透析治療期間所增加的氧化壓力。總結論，維生素B-6和穀胱甘肽可能分別降低高同半胱胺酸血症的血液透析病人的發炎反應和氧化壓力。

關鍵字

慢性腎臟病 ； 血液透析 ； 發炎反應 ； 同半胱胺酸 ； B-維生素 ； 穀胱甘肽氧化壓力

並列摘要

Nephritis, renal syndrome and nephropathy are the ninth cause of death in Taiwan according to 2019 report of Ministry of Health and Welfare of Taiwan. Patients with chronic kidney disease (CKD) and patients who are undergoing hemodialysis (HD) typically present with a long term, low-grade inflammatory status. This status is associated with poor clinical outcomes and confers a high risk of death. A low vitamin B-6 status and hyperhomocysteinemia are also common in patients with CKD and patients undergoing HD. Hyperhomocysteinemia can increase oxidative stress, which subsequently initiates an inflammatory response. The active form of vitamin B-6, pyridoxal 5’- phosphate (PLP), is involved in homocysteine transsulfuration and serves as a coenzyme in the production of cytokines and other polypeptide regulators that drive the inflammatory response. Whether homocysteine and vitamin B-6 status dependently or independently affect the inflammatory status of patients with CKD and patients on HD has not been fully explored. We conducted a cross-sectional study to investigate this question in 68 patients with CKD and 68 patients on HD. We found that plasma PLP levels negatively correlated with C-reactive protein (CRP) levels (n=136, partial γs = - 0.21, p < 0.05); plasma pyridoxal (PL) significantly negatively correlated with interleukin-10 (IL-10) levels (partial γs = - 0.24, p < 0.05); and plasma PLP plus PL levels significantly negatively correlated with CRP levels (partial γs = - 0.20, p < 0.05) and positively correlated with interleukin-1β (IL-1 β) levels (partial γs = 0.22, p < 0.05). We obtained consistent results even when adjusting for the plasma homocysteine levels. In contrast, plasma homocysteine concentrations did not correlate with markers of the inflammatory response. When patients with CKD have inadequate vitamin B-6 intake, the inflammatory response might increase. Although the plasma homocysteine concentration did not correlate with the inflammatory response in patients with CKD and patients on HD, we observed that all patients on HD were in a hyperhomocysteinemic state before HD.

HD is the best renal replacement therapy available to patients with end stage renal disease (ESRD) before receiving a kidney transplant. However, the process of dialysis, especially adequate dialysis, might increase the loss of water-soluble vitamins. This effect can in turn affect homocysteine metabolism. We therefore conducted another a cross-sectional study to investigate the relationship between nutritional levels of B-vitamin (folate, vitamin B-6 and vitamin B-12) and changes in homocysteine levels before and after HD in patients receiving adequate or inadequate dialysis. We found that while plasma homocysteine, cysteine, folate, PLP and vitamin B-12 levels were significantly reduced after HD in all patients, ~50% of the patients still exhibited hyperhomocysteinemia. Plasma vitamin B-12 levels in both the adequate (Kt/V: 1.21-1.83, n = 48) and inadequate (Kt/V: 0.9-1.2,n = 20) dialysis groups negatively correlated with plasma homocysteine levels both before and after HD, but plasma folate and PLP levels were not correlated with homocysteine levels at either time point in both groups. The plasma vitamin B-12 level thus seems to be the only nutritional B-vitamin that is associated with changes in plasma homocysteine levels, even though folate and vitamin B-6 are also involved in homocysteine metabolism. The exact reason for this difference now warrants further investigation.

Cysteine is concomitantly removed with plasma homocysteine during HD. Cysteine is a rate-limiting amino acid that is required for glutathione (GSH) synthesis and its plasma levels can affect the antioxidant capacities of patients undergoing HD. We thus conducted a final cross-sectional study to determine the relationships among GSH, glutathione disulfide (GSSG) and its redox status changes, and changes in plasma cysteine levels or oxidative stress in patients undergoing HD. We found that plasma cysteine, GSH and GSSG levels were significantly depleted after HD compared to the levels before HD. However, the plasma malondialdehyde (MDA) level, GSH/GSSG ratio and GSH redox potential remained constant during the HD session. Plasma GSH and GSSG levels were positively associated with the plasma MDA level after HD, while the GSH redox potential was negatively associated with plasma MDA levels after HD. Plasma GSH and GSSG levels, the GSH/GSSG ratio and GSH redox potential were not associated with plasma cysteine levels before or after HD. Plasma GSH and GSSG thus seem to be well utilized during an HD session as a result of increased oxidative stress.

The results of these three cross-sectional studies imply that patients with CKD and patients undergoing HD are able to maintain an adequate plasma vitamin B-6 status to reduce the inflammatory response. Patients undergoing HD should monitor their vitamin B-12 status before and after receiving dialysis to alleviate the effects of hyperhomocysteinemia. These patients might also have higher GSH demands to cope with increased oxidative stress during an HD session. Together, the overall conclusion was that vitamin B-6 and GSH might reduce the inflammatory response and oxidative stress in hemodialysis patients with hyperhomocysteinemia, respectively.

並列關鍵字

chronic kidney disease ； hemodialysis ； inflammatory response ； homocysteine ； B-vitamins ； glutathione ； oxidative stress.

參考文獻

Alhamdani MS. Impairment of glutathione biosynthetic pathway in uraemia and dialysis. Nephrol Dial Transplant 2005;20:124-128.

Anderson BB, Newmark PA, Rawlins M, Green R. Plasma binding of vitamin B6 compounds. Nature 1974;250:502-504.

Annual report on Kidney Disease in Taiwan 2018:1-316. Issue by the National Health Research Institutes & the Taiwan Society of Nephrology.

Babaei M, Dashti N, Lamei N, Abdi K, Nazari F, Abbasian S, Gerayeshnejad S. Evaluation of plasma concentrations of homocysteine, IL-6, TNF-alpha, hs-CRP, and total antioxidant capacity in patients with end-stage renal failure. Acta Medica Iranica 2014;52(12):893-898.

Bates CJ. Vitamin analysis. Ann Clin Biochem 1997;34:599-626.