長期鉛暴露工人Metallothionein 1A 2A基因多型性組合與腎功能之相關分析研究

The Association of Metallothionein 1A 2A Genetic Polymorphism Combinations and Renal Effects in Chronic Lead-Exposed Workers

楊鎮誠(Chen-Cheng Yang)

指導教授 ： 莊弘毅

高雄醫學大學/健康科學院/公共衛生學系職業安全衛生碩士班/碩士(2015年)

摘要

研究背景
鉛毒性在公共衛生是重要的議題。它可以造成多重器官的傷害，包括腎毒性。金屬硫蛋白(metallothionein, MT)是一個富含半胱胺酸、低分子量且具有消除重金屬毒性的蛋白。在具有功能的金屬硫蛋白基因中，金屬硫蛋白1A基因及2A基因存在人體的所有器官，然而，金屬硫蛋白1A基因及2A基因的多型性是如何影響鉛腎毒性之研究相對稀少。
研究目的
本研究之目的是探討長期鉛暴露工人的血鉛濃度與腎功能生理指標之間的關係，以及金屬硫蛋白1A基因及2A基因多型性組合是否影響該關係的變化。
材料與方法
在485位受試者告知同意並簽署受試同意書後，為受試者安排年度身體檢查並收集血液檢體。將血鉛濃度、血漿肌酐酸、血漿尿酸、尿液肌肝酸、尿液尿酸及尿液乙酰氨基葡萄糖苷酶進行測量與分析。此外，萃取基因並且以即時聚合酶連鎖反應儀進行基因型研究，分析的基因型包括2個金屬硫蛋白1A基因 (rs11640851與rs8052394) 及2個金屬硫蛋白2A基因 (rs10636與rs28366003)。再者，將金屬硫蛋白1A2A基因之多型性進行分組。分組原則是將基因分為野生型及變異型，以rs11640851為例，CC為野生型、CA及AA為變異型，此原則用於其他三個基因多型性，一共組成金屬硫蛋白1A及2A的16組基因多型性組合。試驗結果以SPSS統計軟體進行描述統計、單因子變異數分析及線性回歸統計分析。
結果
在調整MT1A2A基因型組合的16組以外的其他干擾因子之後，尿液尿酸與時間加權累積血鉛指數具有顯著的負相關(β 值-0.20，p值0.0018)。而且，他們彼此之間的關聯性會受的16組基因型組合分組的修正。第6組，第7組，第9組與第12組對鉛毒性在尿液尿酸為較易感受型的組別(分別β值為-13.52，p 值0.0008；β值為-9.20，p 值0.019；β值為-9.70，p 值0.041；β值-10.97，p值0.0047)，而第5組則為較不易感受鉛毒性的基因型組別(β值12.47，p值0.0047)。
結論
尿液尿酸與乙酰氨基葡萄糖苷酶應為鉛腎毒性適合的指標。MT1A2A基因型組合的16組會影響尿液尿酸與時間加權累積血鉛指數的關係。對於時間加權累積血鉛指數與尿液尿酸的關聯性，第6組、第7組、第9組及第12組為較易感受族群，第5組則為較非易感受族群。

關鍵字

金屬硫蛋白 ； 單一核甘酸多型性 ； 時間加權累積血鉛指數 ； 尿液尿酸 ； 尿液乙酰氨基葡萄糖苷酶

並列摘要

Background
Lead toxicity is an important public health issue. It causes multiple organs damage, and nephrotoxicity is included. Metallothionein (MT) is a cysteine-rich, low molecular weight protein with function of heavy metal detoxification. Among the functional MT gene, MT1A and MT2A are existed in all organs in human. However, study about how the MT1A and MT2A single nucleotide polymorphisms (SNPs) influence the lead nephropathy is relatively scarce.
Objectives
Our aim is to investigate the association of blood lead levels and renal biomarkers in chronic occupational lead-exposed workers, and to study whether the association was affected by the combinations of MT1A and MT2A SNPs.
Materials and Methods
Blood samples were collected from 485 participants during their annual health examination after informed consent letters were obtained. The blood lead level, serum creatinine, serum uric acid, urinary creatinine, urinary uric acid, and urinary N-acetyl-beta-d-glucosaminidase (NAG) were measured and analyzed. DNA was extracted and used for real-time PCR of type 2 MT1A SNPs (rs11640851 and rs8052394) and 2 MT2A SNPs (rs10636 and rs28366003). Furthermore, we classified our participants into wild type genetic carriers and variant type ones. In MT1A rs11640851, we regarded the CC carrier as wild type, while CA and AA carriers as variant types. The same principle of classification was also applied in MT1A rs8052394, MT2A rs10636 and rs28366003. Then, we combined the wide type and variant type of these 4 SNPs into 16 different groups. Data was treated for descriptive analysis, one-way ANOVA, and multiple linear regressions by SPSS.
Result
Urine uric acid had significantly negative association with time-weighted index of cumulative blood lead (TWICL) after adjusting other potential confounders except 16 groups of MT1A2A SNPs combination (β -0.20, p value 0.0018). Moreover, the association was modified by 16 groups of SNPs combination. For urine uric acid, group 6th, 7th, 9th and group 12th were more susceptible to lead toxicity (β -13.52, p value 0.0008; β -9.20, p value 0.019; β -9.70, p value 0.041; β -10.97, p value 0.0047), while group 5th was less susceptible to lead toxicity (β 12.47, p value 0.0047).
Conclusion
In conclusion, urinary uric acid and urinary NAG might be considered as proper indicators of lead nephrotoxicity. Moreover, MT1A2A combination 16 groups is a modifier of TWICL on urinary uric acid. Group 6th, 7th, 9th, and 12th are more susceptible to lead toxicity, while group 5th is less susceptible to lead toxicity.

並列關鍵字

Metallothionein ； single nucleotide polymorphisms ； time-weighted index of cumulative blood lead ； urine uric acid ； urine N-acetyl-beta-d-glucosaminidase (NAG)

參考文獻

Reference

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