探討脂蛋白元AV基因單一核苷酸多型性與HIV患者接受蛋白酶抑制劑治療後血漿中高三酸甘油酯濃度之相關性

Determination of the association between particular APOA5 SNPs and elevated plasma TG level after protease inhibitor treatment in HIV patients

柯惟信(Wei-Shin Ko)

指導教授 ： 張淑媛

國立臺灣大學/醫學院/醫學檢驗暨生物技術學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.00071

摘要

高效能抗反轉錄病毒療法（HAART）已大幅地改善HIV感染者之健康狀況，然而HAART所使用之某些藥物卻可能帶來一些非期望之副作用，常見者如脂肪代謝異常而造成血脂濃度過高，進而增加了發生心血管疾病之風險。某些HAART所搭配之藥物，特別是HIV蛋白酶抑制劑（Protease Inhibitor ; PI），與患者接受治療後所產生的高血脂症有顯著的相關性，但對於不同患者的影響程度不一。脂蛋白元在脂肪的代謝過程中扮演重要角色，例如近年發現的脂蛋白元AV以及脂蛋白元CIII皆是調控血脂濃度的重要因子。脂蛋白元基因本身即具多型性，已知某些單一核苷酸多型性（SNP）的存在與高三酸甘油酯血症相關，例如APOA5 SNP1 (1891T>C)、SNP2 (IVS3 + 476G>A)、SNP3 (–1131T>C)以及c.553G>T。過去也有報導指出某些APOC3單一核苷酸多型性與HIV患者接受HAART治療後所產生的高三酸甘油酯血症相關，例如：3238C>G、－482C>T以及－455T>C；此外SREBP-1c基因之3’322C>G亦可能與之相關。因此我們想要了解在我國的HIV感染者中，在脂肪代謝相關基因上某些單一核苷酸多型性的存在是否較容易造成HAART治療後之高三酸甘油酯血症。

本研究針對台大醫院之310位HIV感染者，我們記錄並統整其接受治療前後之各項數值，並依照其使用藥物的種類分成PI-based HAART以及NNRTI-based HAART兩組以進行分析及比較。我們以PCR-RFLP的方法，針對上述八個單一核苷酸多型性位點，先以PCR複制特定基因片段並以限制酵素切割反應之結果來判斷其基因型。分析結果發現，接受PI-based HAART的患者在用藥後半年即可觀察到TG值顯著地增加；進一步針對基因型做探討，若於APOA5 SNP3此位點帶有一或兩個變異型核苷酸，於用藥半年後即有較高之風險可能產生高三酸甘油酯血症：若為heterozygous (T/C)，其odds ratio為1.82 (95% C.I.=1.55~9.41)，若為mutant type (C/C)，其odds ratio為11.19 (95% CI=2.29~54.73)。此外於APOA5 c.553G>T此位點帶有一個以上之變異型核苷酸（G/T或T/T），亦於用藥半年後具有較高之高三酸甘油酯血症風險，其odds ratio為3.61 (95% C.I.=1.31~9.95)。然而在我們的受試者中，APOA5 SNP3以及c.553G>T之基因型呈現連鎖不平衡的情況，分析結果顯示：若將這兩個位點之基因型一同納入迴歸分析的模式當中，在調整各變項的分布狀況之後，僅SNP3與TG值有顯著的相關，因此SNP3可能是一個較為顯著的影響因子。觀察用藥後半年之TG值，在NNRTI-based HAART的患者中則沒有見到基因型上的差異。經由患者用藥後三年內的長期觀察分析亦指出，上述兩個單一核苷酸多型性與接受PI後所造成的高三酸甘油酯血症有顯著相關，而在NNRTI-based HAART的患者中則是APOA5 SNP1及SNP3與之相關；然而在我們的受試者族群中，SNP1及SNP3在遺傳上有連鎖不平衡的情況，因此SNP3較可能是造成高三酸甘油酯血症之危險因子。此外在本篇研究中，APOC3各SNP以及SREBP-1c 3’322C>G都不是造成患者在HAART治療後產生高三酸甘油酯血症的風險因子。我們的研究提供了一個訊息：在替台灣地區的HIV患者選擇藥物時，可以事先篩選其是否帶有APOA5 SNP3以及c.553G>T之變異型核苷酸，以期降低治療所帶來之高三酸甘油酯血症之風險。

關鍵字

HIV ； 蛋白酶抑制劑 ； 脂蛋白元AV ； 單一核苷酸多型性 ； 三酸甘油酯

並列摘要

Highly Active Anti-Retroviral Therapy (HAART) has greatly improved the clinical outcomes of HIV-1 infected individuals. However, some of the HAART regimens may incur some unexpected side effects, such as defect in lipid metabolism, which could possibly increase the risk for cardiovascular diseases. Some antiretroviral drugs, especially protease inhibitors (PIs), are strongly associated with HAART-related hyperlipidemia, yet some individual variations have been observed, implicating the involment of some genetic factors. It’s well known that apolipoprotein plays an important role in lipid metabolism, such as apoCIII and a newly discovered apolipoprotein, apoAV. The single nucleotide polymorphisms (SNPs) in these apolipoprotein genes were reported to be associated with hyprelipidemia in normal population. Further, some of APOC3 SNPs were defined to be associated with HAART-related hypertriglyceridemia in PI treated HIV patients. Another polymorphism, SREBP-1c 3’322C>G, was also shown to be related with PI-associated hypertriglyceridemia. Therefore, we would like to figure out if there is some correlation between HAART-associated hypertriglyceridemia and the gene polymorphisms in Taiwanese population.

In this study, data from 310 HIV-positive patients from National Taiwan University Hospital was collected before and after HAART therapy. They were divided into two groups, PI-based HAART and NNRTI-based HAART, according to the regimen they underwent. PCR-RFLP were performed to determine the SNP polymorphisms at SNP1 (1891T>C), SNP2 (IVS3 + 476G>A), SNP3 (–1131T>C), c.553G>T of APOA5, 3238C>G、－482C>T, －455T>C of APOC3, and 3’322C>G of SREBP-1c. After treatment, patients underwent PI-based HAART had a significantly elevated TG level after 6 months. We found a strong association between APOA5 SNP3 and elevated plasma TG level in patients receiving PIs for 6 months. The minor C allele carriers may have a higher risk to have hypertriglyceridemia: the odds ratios are 1.82 (95% C.I.=1.55~9.41) for heterozygous (T/C) carrier and 11.19 (95% C.I.=2.29~54.73) for homozygous minor allele (C/C) carrier. Besides, minor allele carriers of APOA5 c.553G>T were also significantly associated with hypertriglyceridemia with an odds ratio of 3.61 (95% C.I.=1.31~9.95). Nevertheless, the two loci described above showed strong linkage disequilibrium (LD) with SNP3 as the stronger predictor for PI associated hypertriglyceridemia. In the NNRTI-based HAART group, we did not find any significant associations between particular genotypes and elevated plasma TG level after 6 months. Longitudinal analysis was also performed by monitoring the patients at a three-year follow-up observation. As a result, in PI treated patients, APOA5 SNP3 and c.553G>T were obvious risk factors for elevated TG level. In the NNRTI treated patients, SNP1 and SNP3 of APOA5 were significant risk factors. However, the effect of SNP1 may be due to its linkage disequilibrium with SNP3, thus making SNP3 the dominant factor. Unlike previous studies, the SNPs of APOC3 and 3’322C>G of SREBP-1c were not significantly associated with plasma TG level among HAART treated patients. In summary, we found that, in our study population, minor allele carriers of SNP3 and c.553G>T of APOA5 had a higher risk of PI-related hypertriglyceridemia. Screening for these genetic variations before therapy may help to avoid PI-related hypertriglyceridemia in Taiwanese HIV patients.

並列關鍵字

HIV ； protrease inhibitor (PI) ； apolipoprotein AV ； single nucleotide polymorphism (SNP) ； triglyceride (TG)

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