陰道滴蟲 （Trichomonas vaginalis）為單細胞原蟲，同時也為全世界傳播最廣的非病毒性性病。在感染人群中，女性由於經期的緣故，生殖道營養含量較男性豐富所以常導致較為嚴重的炎症。陰道滴蟲病的主要治療藥物為甲硝唑(Metronidazole; MTZ)，該藥物在厭氧環境下可被還原為具有功能性的藥物。而其還原態可以藉由釋放活性氧化物(ROS)來殺死病原體。在研究鐵與MTZ的交互作用中便發現，鐵可以使MTZ的毒殺能力增強，這些跡象便讓我們聯想到於鐵死亡該細胞死亡途徑，該途徑便是因為鐵藉由芬頓反應(Fenton reaction)生成ROS並攻擊細胞膜上的磷脂質，造成過氧化後破裂。而在初步改變培養液當中的鐵濃度時便發現，單純增加鐵濃度並不會影響陰道滴蟲的生長情形，但同時給予鐵以及鐵死亡誘導劑時便可以觀察到陰道滴蟲族群有進一步的下降。與此同時，我們在試圖藉由抑制劑抑制鐵死亡時卻發現其無法在陰道滴蟲上作用，顯示其可能參與的死亡途徑不同。同時，抗藥性蟲株 (MTZ-R)同樣也對於鐵死亡誘導劑等具有一定程度抗性。在解讀基因集變異分析 (gene set variation analysis; GSVA)的結果中發現，MTZ-R的蟲株 (ATCC 30238, 50142, 50143)在給予MTZ治療後穀胱甘肽代謝 (glutathione metabolism)的途徑相對MTZ-S (ATCC 30001, 30236, 50167)來的高，初步披露MTZ-R在抗氧化系統上的能力。相關抗氧化基因表現上也發現到其在鐵死亡誘導劑RSL3或是MTZ的治療下，硫氧還蛋白家族的基因表現量在抗藥性蟲株上明顯高於敏感性蟲株。鑒於種種證據，我們接著便嘗試給予硫氧還蛋白還原酶(Thioredoxin reductase, TrxR)的抑制劑來觀察抗藥性蟲株的存活程度。在利用絲裂黴素C (Mitomycin C, MMC)與MTZ共同處理後可以發現其族群死亡的數量比起單獨給予任一種藥物來的有效，而利用Loewe additivity計算兩種藥物的後證明其存在協同效果。本研究首次證明陰道滴蟲並不存在鐵死亡的特性，且與其共通的抗氧化機制可能參與在MTZ的抗性當中。並且通過這次加乘試驗我們首次發現MMC與MTZ可形成協同作用，加強對於抗藥性蟲株的毒殺能力。

Trichomonas vaginalis (T.v) is the most common non-viral sexually transmitted disease, its infection rate is more prevalent than gonorrhea and chlamydia in the US. Metronidazole (MTZ) is the standard treatment, but resistance is becoming a serious problem. Previous researchers have discussed the interaction between iron and MTZ and pulled out the possibility of ferroptosis. Thus, in this study we urged to discover whether the mechanism of MTZ toxicity is through ferroptosis linked pathway, after treating with Fer-1 and DIP both couldn’t rescue the cell survival caused by RSL3 and MTZ, and non-obvious lipid peroxidation gave a negative answer in ferroptosis, investigating the possible cell death pathway through qPCR revealed that thioredoxin system, especially thioredoxin reductase (TrxR), might plays a shared mechanism in RSL3 and MTZ killing. Thus, the inhibition of TrxR be an imperative mission, we choose mitomycin C (MMC) as a potential TrxR inhibitor, not only its similar biochemical feature with MTZ, its combination of MTZ were reported to have ability to against C.difficile infection. After calculating the synergy score of MMC and MTZ by using SynergyFinder revealed that it does have synergistic ability to against MTZ-R strain. Gene expression level in metabolism-related genes also revealed that combined group will change the glucose metabolism pathway, as for pentose phosphate pathway (PPP), the combination group will elevate the expression of these genes. In conclusion, the research revealed that there is no ferroptosis exists in T.v, and that its common antioxidant mechanisms may be involved in metronidazole (MTZ) resistance. Furthermore, through combination experiments, we have, for the first time, discovered that mitomycin C (MMC) and MTZ can act synergistically to enhance the cytotoxicity against drug-resistant strains.

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