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Li S, Chen X, Zhou J, Xie Z, Shang M, He L, Liang P, Chen T, Mao Q, Liang C, Li X, Huang Y, Yu X. Amino acids serve as an important energy source for adult flukes of Clonorchis sinensis. PLoS Negl Trop Dis 2020; 14:e0008287. [PMID: 32352979 PMCID: PMC7217481 DOI: 10.1371/journal.pntd.0008287] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 05/12/2020] [Accepted: 04/10/2020] [Indexed: 12/19/2022] Open
Abstract
Clonorchiasis, caused by chronic infection with Clonorchis sinensis (C. sinensis), is an important food-borne parasitic disease that seriously afflicts more than 35 million people globally, resulting in a socioeconomic burden in endemic regions. C. sinensis adults long-term inhabit the microaerobic and limited-glucose environment of the bile ducts. Energy metabolism plays a key role in facilitating the adaptation of adult flukes to crowded habitat and hostile environment. To understand energy source for adult flukes, we compared the component and content of free amino acids between C. sinensis-infected and uninfected bile. The results showed that the concentrations of free amino acids, including aspartic acid, serine, glycine, alanine, histidine, asparagine, threonine, lysine, hydroxylysine, and urea, were significantly higher in C. sinensis-infected bile than those in uninfected bile. Furthermore, exogenous amino acids could be utilized by adult flukes via the gluconeogenesis pathway regardless of the absence or presence of exogenous glucose, and the rate-limiting enzymes, such as C. sinensis glucose-6-phosphatase, fructose-1,6-bisphosphatase, phosphoenolpyruvate carboxykinase, and pyruvate carboxylase, exhibited high expression levels by quantitative real-time PCR analysis. Interestingly, no matter whether exogenous glucose was present, inhibition of gluconeogenesis reduced the glucose and glycogen levels as well as the viability and survival time of adult flukes. These results suggest that gluconeogenesis might play a vital role in energy metabolism of C. sinensis and exogenous amino acids probably serve as an important energy source that benefits the continued survival of adult flukes in the host. Our study will be a cornerstone for illuminating the biological characteristics of C. sinensis and the host-parasite interactions. Clonorchiasis, closely related to cholangiocarcinoma and hepatocellular carcinoma, has led to a negative socioeconomic impact in global areas especially some Asian endemic regions. Owing to the emergence of drug resistance and hypersensitivity reactions after the massive and repeated use of praziquantel as well as the lack of effective vaccines, searching for new strategies that prevent and treat clonorchiasis has become an urgent matter. Clonorchis sinensis, the causative agent of clonorchiasis, long-term inhabits the microaerobic and limited-glucose environment of the bile ducts. Adequate nutrients are essential for adult flukes to resist the adverse condition and survive in the crowed habitat. Studies on energy metabolism of adult flukes are beneficial for further exploring host-parasite interactions and developing novel anti-parasitic drugs. Our results suggest that gluconeogenesis probably plays a vital role in energy metabolism of Clonorchis sinensis and exogenous amino acids might be an essential energy source for adult flukes to successfully survive in the host. Our foundational study opens a new avenue for explaining energy metabolism of Clonorchis sinensis and provides a valuable strategy that the gluconeogenesis pathway will be a potential and novel target for the prevention and treatment of clonorchiasis.
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Affiliation(s)
- Shan Li
- Department of Pathology and Pathophysiology, Henan University of Chinese Medicine, Zhengzhou, Henan, People’s Republic of China
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
- Key Laboratory for Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou, Guangdong, People’s Republic of China
| | - Xueqing Chen
- Clinical Laboratory, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong, People’s Republic of China
| | - Juanjuan Zhou
- Zhengzhou Key Laboratory for Children’s Infection and Immunity, Children’s Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan, People’s Republic of China
| | - Zhizhi Xie
- Clinical Laboratory, Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
| | - Mei Shang
- Clinical Laboratory, Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
| | - Lei He
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
- Key Laboratory for Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou, Guangdong, People’s Republic of China
| | - Pei Liang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
- Key Laboratory for Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou, Guangdong, People’s Republic of China
| | - Tingjin Chen
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
- Key Laboratory for Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou, Guangdong, People’s Republic of China
| | - Qiang Mao
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
- Key Laboratory for Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou, Guangdong, People’s Republic of China
| | - Chi Liang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
- Key Laboratory for Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou, Guangdong, People’s Republic of China
| | - Xuerong Li
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
- Key Laboratory for Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou, Guangdong, People’s Republic of China
| | - Yan Huang
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
- Key Laboratory for Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou, Guangdong, People’s Republic of China
- * E-mail: (YH); (XY)
| | - Xinbing Yu
- Department of Parasitology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, Guangdong, People’s Republic of China
- Key Laboratory for Tropical Diseases Control, Sun Yat-Sen University, Ministry of Education, Guangzhou, Guangdong, People’s Republic of China
- * E-mail: (YH); (XY)
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