Kundu Sushmita, Das Suman, Maitra Priyanka, Halder Prolay, Koley Hemanta, Mukhopadhyay Asish K, Miyoshi Shin-Ichi, Dutta Shanta, Chatterjee Nabendu Sekhar, Bhattacharya Sushmita
Division of Biochemistry, ICMR-National Institute for Research in Bacterial Infections (Formerly ICMR-National Institute of Cholera and Enteric Diseases), Kolkata, India.
Division of Bacteriology, ICMR-National Institute for Research in Bacterial Infections (Formerly ICMR-National Institute of Cholera and Enteric Diseases), Kolkata, India.
mSphere. 2025 May 27;10(5):e0082424. doi: 10.1128/msphere.00824-24. Epub 2025 Apr 22.
Cholera, a diarrheal disease caused by the gram-negative bacterium , remains a global health threat in developing countries due to its high transmissibility and increased antibiotic resistance. There is a pressing need for alternative strategies, with an emphasis on anti-virulent approaches to alter the outcome of bacterial infections, given the increase in antimicrobial-resistant strains. causes cholera by secreting virulence factors in the intestinal epithelial cells. These virulence factors facilitate bacterial colonization and cholera toxin production during infection. Here, we demonstrate that sodium butyrate (SB), a small molecule, had no effect on bacterial viability but was effective in suppressing the virulence attributes of . The production of cholera toxin (CT) was significantly reduced in a standard El Tor strain and two clinical isolates when grown in the presence of SB. Analysis of mRNA and protein levels further revealed that SB reduced the expression of the ToxT-dependent virulence genes like and . DNA-protein interaction assays, conducted at cellular (ChIP) and conditions (EMSA), indicated that SB weakens the binding between ToxT and its downstream promoter DNA, likely by blocking DNA binding. Furthermore, the anti-virulence efficacy of SB was confirmed in animal models. These findings suggest that SB could be developed as an anti-virulence agent against serving as a potential alternative to conventional antibiotics or as an adjunctive therapy to combat cholera.
The world has been facing an upsurge in cholera cases since 2021, a similar trend continuing into 2022, with over 29 countries reporting cholera outbreaks (World Health Organization, 16 December 2022, Disease Outbreak News, Cholera-global situation). Treatment of cholera involves oral rehydration therapy coupled with antibiotics to reduce the duration of the illness. However, in recent years, indiscriminate use of antibiotics has contributed to the emergence of antibiotic-resistant strains. In this study, we have addressed the problem of antibiotic resistance by targeting virulence factors. Screening various compounds using methods led to the identification of a small molecule, SB, that inhibits the virulence cascade in . We demonstrated that (i) SB intervened in ToxT protein-DNA binding and subsequently affected the expression of ToxT-regulated virulence genes ( and ) and (ii) SB is a potential therapeutic candidate for the development of a novel antimicrobial agent.
霍乱是一种由革兰氏阴性菌引起的腹泻病，由于其高传播性和日益增加的抗生素耐药性，在发展中国家仍然是全球健康威胁。鉴于抗菌耐药菌株的增加，迫切需要替代策略，重点是采用抗毒力方法来改变细菌感染的结果。通过在肠道上皮细胞中分泌毒力因子来引发霍乱。这些毒力因子在感染期间促进细菌定植和霍乱毒素的产生。在此，我们证明小分子丁酸钠（SB）对细菌活力没有影响，但能有效抑制的毒力特性。在标准的埃尔托菌株和两个临床分离株中，当在SB存在的情况下生长时，霍乱毒素（CT）的产生显著减少。对mRNA和蛋白质水平的分析进一步表明，SB降低了如和等ToxT依赖性毒力基因的表达。在细胞水平（ChIP）和体外条件（EMSA）下进行的DNA-蛋白质相互作用测定表明，SB可能通过阻断DNA结合来削弱ToxT与其下游启动子DNA之间的结合。此外，SB在动物模型中的抗毒力功效得到了证实。这些发现表明，SB可以开发成为一种针对的抗毒力药物，作为传统抗生素的潜在替代品或作为对抗霍乱的辅助疗法。
自2021年以来，全球霍乱病例激增，这一趋势持续到2022年，超过29个国家报告了霍乱疫情（世界卫生组织，2022年12月16日，疾病爆发新闻，霍乱全球形势）。霍乱的治疗包括口服补液疗法和使用抗生素以缩短病程。然而，近年来，抗生素的滥用导致了抗生素耐药菌株的出现。在本研究中，我们通过靶向毒力因子解决了抗生素耐药性问题。使用方法筛选各种化合物导致鉴定出一种小分子SB，它能抑制中的毒力级联反应。我们证明：（i）SB干预了ToxT蛋白-DNA结合，随后影响了ToxT调节的毒力基因（和）的表达；（ii）SB是开发新型抗菌剂的潜在治疗候选物。
