Macedo Carolina Machado, Saraiva Francis Monique de Souza, Paula Jéssica Isis Oliveira, Nascimento Suelen de Brito, Costa Débora de Souza Dos Santos, Costa Paulo Roberto Ribeiro, Dias Ayres Guimarães, Paes Marcia Cristina, Nogueira Natália Pereira
Laboratório de Interação de Tripanossomatídeos e Vetores, Departamento de Bioquímica, IBRAG - Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
Laboratório de Hematologia, Departamento de Patologia, Faculdade de Medicina, Universidade Federal Fluminense, Rio de Janeiro, Brazil.
Front Microbiol. 2021 Apr 15;12:617504. doi: 10.3389/fmicb.2021.617504. eCollection 2021.
Chagas disease, which is caused by , establishes lifelong infections in humans and other mammals that lead to severe cardiac and gastrointestinal complications despite the competent immune response of the hosts. Furthermore, it is a neglected disease that affects 8 million people worldwide. The scenario is even more frustrating since the main chemotherapy is based on benznidazole, a drug that presents severe side effects and low efficacy in the chronic phase of the disease. Thus, the search for new therapeutic alternatives is urgent. In the present study, we investigated the activity of a novel phenyl-tert-butyl-nitrone (PBN) derivate, LQB303, against . LQB303 presented trypanocidal effect against intracellular [IC/48 h = 2.6 μM] and extracellular amastigotes [IC/24 h = 3.3 μM] , leading to parasite lysis; however, it does not present any toxicity to host cells. Despite emerging evidence that mitochondrial metabolism is essential for amastigotes to grow inside mammalian cells, the mechanism of redox-active molecules that target mitochondrion is still poorly explored. Therefore, we investigated if LQB303 trypanocidal activity was related to the impairment of the mitochondrial function of amastigotes. The investigation showed there was a significant decrease compared to the baseline oxygen consumption rate (OCR) of LQB303-treated extracellular amastigotes of , as well as reduction of "proton leak" (the depletion of proton motive force by the inhibition of F1Fo ATP synthase) and "ETS" (maximal oxygen consumption after uncoupling) oxygen consumption rates. Interestingly, the residual respiration ("ROX") enhanced about three times in LQB303-treated amastigotes. The spare respiratory capacity ratio (SRC: cell ability to meet new energy demands) and the ATP-linked OCR were also impaired by LQB303 treatment, correlating the trypanocidal activity of LQB303 with the impairment of mitochondrial redox metabolism of amastigotes. Flow cytometric analysis demonstrated a significant reduction of the ΔΨm of treated amastigotes. LQB303 had no significant influence on the OCR of treated mammalian cells, evidencing its specificity against mitochondrial metabolism. Our results suggest a promising trypanocidal activity of LQB303, associated with parasite bioenergetic inefficiency, with no influence on the host energy metabolism, a fact that may point to an attractive alternative therapy for Chagas disease.
恰加斯病由[病原体名称缺失]引起，可在人类和其他哺乳动物体内建立终身感染，尽管宿主具有有效的免疫反应，但仍会导致严重的心脏和胃肠道并发症。此外，它是一种被忽视的疾病，全球有800万人受其影响。由于主要的化疗药物是苯硝唑，这种药物在疾病的慢性期会产生严重的副作用且疗效不佳，情况更加令人沮丧。因此，迫切需要寻找新的治疗方法。在本研究中，我们调查了一种新型苯基叔丁基硝酮（PBN）衍生物LQB303对[病原体名称缺失]的活性。LQB303对细胞内无鞭毛体[IC/48小时 = 2.6 μM]和细胞外无鞭毛体[IC/24小时 = 3.3 μM]具有杀锥虫作用，导致寄生虫裂解；然而，它对宿主细胞没有任何毒性。尽管越来越多的证据表明线粒体代谢对于无鞭毛体在哺乳动物细胞内生长至关重要，但针对线粒体的氧化还原活性分子的作用机制仍未得到充分探索。因此，我们研究了LQB303的杀锥虫活性是否与无鞭毛体线粒体功能的损害有关。研究表明，与未处理的细胞外无鞭毛体的基线氧消耗率（OCR）相比，LQB303处理后的细胞外无鞭毛体的OCR显著降低，同时“质子泄漏”（通过抑制F1Fo ATP合酶消耗质子动力）和“电子传递体系”（解偶联后的最大氧消耗）的氧消耗率也降低。有趣的是，在LQB303处理的无鞭毛体中，残余呼吸（“ROX”）增强了约三倍。LQB303处理还损害了备用呼吸能力比率（SRC：细胞满足新能量需求的能力）和与ATP相关的OCR，这将LQB303的杀锥虫活性与无鞭毛体线粒体氧化还原代谢的损害联系起来。流式细胞术分析表明，处理后的无鞭毛体的线粒体膜电位（ΔΨm）显著降低。LQB303对处理后的哺乳动物细胞的OCR没有显著影响，证明了其对线粒体代谢的特异性。我们的结果表明LQB303具有有前景的杀锥虫活性，与寄生虫生物能量效率低下相关，且对宿主能量代谢没有影响，这一事实可能为恰加斯病指明一种有吸引力的替代疗法。
