Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran; Department of Biology, Central Tehran Branch, Islamic Azad University, Tehran, Iran.
Department of Parasitology, Pasteur Institute of Iran, Tehran, Iran.
Acta Trop. 2024 Jun;254:107190. doi: 10.1016/j.actatropica.2024.107190. Epub 2024 Mar 18.
Pentavalent antimonials are the mainstay treatment against different clinical forms of leishmaniasis. The emergence of resistant isolates in endemic areas has led to treatment failure. Unraveling the underlying resistance mechanism would assist in improving the treatment strategies against resistant isolates. This study aimed to investigate the RNA expression level of glutathione synthetase (GS), Spermidine synthetase (SpS), trypanothione synthetase (TryS) genes involved in trypanothione synthesis, and thiol-dependent reductase (TDR) implicated in drug reduction, in antimony-sensitive and -resistant Leishmania tropica isolates. We investigated 11 antimony-resistant and 11 antimony-sensitive L. tropica clinical isolates from ACL patients. Drug sensitivity of amastigotes was determined in mouse macrophage cell line J774A.1. The RNA expression level in the promastigote forms was analyzed by quantitative real-time PCR. The results revealed a significant increase in the average expression of GS, SpS, and TrpS genes by 2.19, 1.56, and 2.33-fold in resistant isolates compared to sensitive ones. The average expression of TDR was 1.24-fold higher in resistant isolates, which was insignificant. The highest correlation coefficient between inhibitory concentration (IC) values and gene expression belonged to the TryS, GS, SpS, and TDR genes. Moreover, the intracellular thiol content was increased 2.17-fold in resistant isolates compared to sensitive ones and positively correlated with IC values. Our findings suggest that overexpression of trypanothione biosynthesis genes and increased thiol content might play a key role in the antimony resistance of L. tropica clinical isolates. In addition, the diversity of gene expression in the trypanothione system and thiol content among L. tropica clinical isolates highlighted the phenotypic heterogeneity of antimony resistance among the parasite population.
五价锑是治疗不同临床形式利什曼病的主要药物。在流行地区，耐药分离株的出现导致了治疗失败。阐明潜在的耐药机制将有助于改进针对耐药分离株的治疗策略。本研究旨在研究涉及三价硫醇合成的谷胱甘肽合成酶（GS）、亚精胺合成酶（SpS）和硫氧还蛋白合成酶（TryS）基因以及参与药物还原的硫醇依赖性还原酶（TDR）的 RNA 表达水平，在锑敏感和耐药的利什曼原虫热带分离株中。我们研究了来自 ACL 患者的 11 个锑耐药和 11 个锑敏感的利什曼原虫热带临床分离株。在巨噬细胞系 J774A.1 中测定了无鞭毛体的药物敏感性。通过实时定量 PCR 分析前鞭毛体形式的 RNA 表达水平。结果显示，与敏感株相比，耐药株中 GS、SpS 和 TrpS 基因的平均表达分别增加了 2.19、1.56 和 2.33 倍。耐药株中 TDR 的平均表达增加了 1.24 倍，但无统计学意义。抑制浓度（IC）值与基因表达之间相关性最高的基因是 TryS、GS、SpS 和 TDR。此外，耐药株的细胞内硫醇含量增加了 2.17 倍，与 IC 值呈正相关。我们的研究结果表明，三价硫醇合成基因的过度表达和硫醇含量的增加可能在利什曼原虫热带临床分离株的锑耐药中起关键作用。此外，利什曼原虫热带临床分离株中三价硫醇系统和硫醇含量的基因表达多样性突出了寄生虫群体中锑耐药的表型异质性。
