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Shao Y, Yuan X, Du B, Zhang X, Li X, Zhang X, Gong P, Zhang N, Wang X, Li J. Neospora caninum peroxiredoxin 1 is an essential virulence effector with antioxidant function. Vet Parasitol 2024; 327:110117. [PMID: 38262172 DOI: 10.1016/j.vetpar.2024.110117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 01/09/2024] [Accepted: 01/13/2024] [Indexed: 01/25/2024]
Abstract
Neospora caninum, an obligate intracellular parasitic protozoan discovered by Dubey in 1988, is the pathogen of neosporosis, which causes neurological symptoms in dogs and abortions in cows. Since there is no effective drug or vaccine against N. caninum, a deeper understanding of the molecules critical to parasite survival inside host cells is necessary. This study aimed to determine the role of N. caninum peroxiredoxin 1 (NcPrx1) in maintaining redox homeostasis and virulence of N. caninum. By determining the localization of NcPrx1 protein and establishing NcPrx1 gene knockout strain (ΔNcPrx1), the roles of NcPrx1 in N. caninum for invasion, replication, growth, oxidative stress, as well as pathogenicity were investigated. Our results showed that a predicted Alkyl Hydroperoxide1 (AHP1) domain was found in the amino acid sequence of NcPrx1, which displayed a high degree of similarity to homologs of several protozoa. Immunofluorescence assay (IFA) indicated that NcPrx1 was a cytoplasmic protein in N. caninum tachyzoites. Compared to wild type (WT) strain, ΔNcPrx1 strain showed reduced plaque area, invasion and egress rates. Reactive oxygen species (ROS) and malondialdehyde (MDA) were accumulated, and total antioxidant capacity (T-AOC) was attenuated in ΔNcPrx1 tachyzoites, which indicated that ΔNcPrx1 strain was more sensitive to oxidative stress. Furthermore, ΔNcPrx1 strain-infected C57BL/6 mice showed improved survival rate, reduced parasite burden, alleviated pathological changes in tissues, and decreased secretions of IL-6, IL-12, TNF-α, and IFN-γ in serum compared to the WT strain group. These findings suggested that NcPrx1 was a virulence factor of N. caninum which played an important role in maintaining the redox homeostasis of the parasite.
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Affiliation(s)
- Yutao Shao
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Xiaodan Yuan
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Boya Du
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Xuancheng Zhang
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Xin Li
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Xu Zhang
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Pengtao Gong
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Nan Zhang
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Xiaocen Wang
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China.
| | - Jianhua Li
- State Key Laboratory for Zoonotic Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China.
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Qian Y, Jiang Y, Hong H, Gao X, Liu W, Chen M, Jin Q, Jin Z, Li X, Wang X, Li J, Liu Q, Zhang X, Zhang N, Wei Z. Pathological characteristics and congenital immunological responses of pigeons-infected with Neospora caninum. Microb Pathog 2023; 182:106224. [PMID: 37423494 DOI: 10.1016/j.micpath.2023.106224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 06/24/2023] [Accepted: 07/02/2023] [Indexed: 07/11/2023]
Abstract
Pigeons are natural intermediate host of Neospora caninum (N. caninum). In comparison to ruminants, N. caninum causes milder clinical symptoms and less financial loss to pigeons. Natural infectious rates and high prevalence of N. caninum in pigeons, and death cases of N. caninum-infected pigeons under experimental conditions have been reported, but the detailed pathological characteristics and congenital immunological responses of pigeons-infected with N. caninum remain not well described. In this study, pigeons were infected intraperitoneally with 107 N. caninum tachyzoites. N. caninum in tissues was detected by qPCR. Pathological changes of tissues were examined by hematoxylin-eosin staining. Blood smears were prepared for counting eosinophils changes in blood. Heterophil extracellular traps (HETs) in vivo and in vitro were quantified by Pico Green. N. caninum-induced HETs structures were observed by immunofluorescence staining. The model of pigeons-infected with N. caninum was successfully established. Lung and duodenum were the main target organs of pigeons-infected with N. caninum. N. caninum caused hemorrhage, edema and inflammatory cell infiltration in liver, pulmonary congestion and hemorrhage, organizational destruction in lung, and shorter villi or even disappear in duodenum. N. caninum also increased the number of eosinophils in blood of pigeons. Moreover, N. caninum-induced HETs release in the congenital immunological system of pigeons were first demonstrated, and the HETs structures were consisted of DNA as the skeleton and modified with citH3 and elastase. N. caninum-induced HETs release was related with NADPH oxidase, TLR 2 and 4, ERK1/2 and p38 MAPK signaling pathways, and glycolysis. In summary, it is the first report on the detailed pathological characteristics and congenital immunological responses of pigeons-infected with N. caninum, which may provide theoretical basis for the prevention and control of Neosporosis in pigeons.
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Affiliation(s)
- Yuxiao Qian
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China
| | - Yuqian Jiang
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China
| | - Hongrong Hong
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China
| | - Xinxin Gao
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China
| | - Wei Liu
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China
| | - Meiyi Chen
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China
| | - Qinqin Jin
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China
| | - Zha Jin
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China
| | - Xin Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xian Road, Changchun, 130062, Jilin, China
| | - Xiaocen Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xian Road, Changchun, 130062, Jilin, China
| | - Jianhua Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xian Road, Changchun, 130062, Jilin, China
| | - Quan Liu
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China
| | - Xichen Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xian Road, Changchun, 130062, Jilin, China
| | - Nan Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, 5333 Xian Road, Changchun, 130062, Jilin, China.
| | - Zhengkai Wei
- College of Life Sciences and Engineering, Foshan University, Foshan, 528225, Guangdong Province, PR China; College of Veterinary Medicine, Southwest University, Chongqing, 400715, China.
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Zhao SS, Tao DL, Chen JM, Wu JP, Yang X, Song JK, Zhu XQ, Zhao GH. RNA sequencing reveals dynamic expression of lncRNAs and mRNAs in caprine endometrial epithelial cells induced by Neospora caninum infection. Parasit Vectors 2022; 15:297. [PMID: 35999576 PMCID: PMC9398501 DOI: 10.1186/s13071-022-05405-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 07/19/2022] [Indexed: 11/10/2022] Open
Abstract
Background The effective transmission mode of Neospora caninum, with infection leading to reproductive failure in ruminants, is vertical transmission. The uterus is an important reproductive organ that forms the maternal–fetal interface. Neospora caninum can successfully invade and proliferate in the uterus, but the molecular mechanisms underlying epithelial-pathogen interactions remain unclear. Accumulating evidence suggests that host long noncoding RNAs (lncRNAs) play important roles in cellular molecular regulatory networks, with reports that these RNA molecules are closely related to the pathogenesis of apicomplexan parasites. However, the expression profiles of host lncRNAs during N. caninum infection has not been reported. Methods RNA sequencing (RNA-seq) analysis was used to investigate the expression profiles of messenger RNAs (mRNAs) and lncRNAs in caprine endometrial epithelial cells (EECs) infected with N. caninum for 24 h (TZ_24h) and 48 h (TZ_48 h), and the potential functions of differentially expressed (DE) lncRNAs were predicted by using Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of their mRNA targets. Results RNA-seq analysis identified 1280.15 M clean reads in 12 RNA samples, including six samples infected with N. caninum for 24 h (TZ1_24h-TZ3_24h) and 48 h (TZ1_48h-TZ3_48h), and six corresponding control samples (C1_24h-C3_24h and C1_48h-C3_48h). Within the categories TZ_24h-vs-C_24h, TZ_48h-vs-C_48h and TZ_48h-vs-TZ_24h, there were 934 (665 upregulated and 269 downregulated), 1238 (785 upregulated and 453 downregulated) and 489 (252 upregulated and 237 downregulated) DEmRNAs, respectively. GO enrichment and KEGG analysis revealed that these DEmRNAs were mainly involved in the regulation of host immune response (e.g. TNF signaling pathway, MAPK signaling pathway, transforming growth factor beta signaling pathway, AMPK signaling pathway, Toll-like receptor signaling pathway, NOD-like receptor signaling pathway), signaling molecules and interaction (e.g. cytokine-cytokine receptor interaction, cell adhesion molecules and ECM-receptor interaction). A total of 88 (59 upregulated and 29 downregulated), 129 (80 upregulated and 49 downregulated) and 32 (20 upregulated and 12 downregulated) DElncRNAs were found within the categories TZ_24h-vs-C_24h, TZ_48h-vs-C_48h and TZ_48h-vs-TZ_24h, respectively. Functional prediction indicated that these DElncRNAs would be involved in signal transduction (e.g. MAPK signaling pathway, PPAR signaling pathway, ErbB signaling pathway, calcium signaling pathway), neural transmission (e.g. GABAergic synapse, serotonergic synapse, cholinergic synapse), metabolism processes (e.g. glycosphingolipid biosynthesis-lacto and neolacto series, glycosaminoglycan biosynthesis-heparan sulfate/heparin) and signaling molecules and interaction (e.g. cytokine-cytokine receptor interaction, cell adhesion molecules and ECM-receptor interaction). Conclusions This is the first investigation of global gene expression profiles of lncRNAs during N. caninum infection. The results provide valuable information for further studies of the roles of lncRNAs during N. caninum infection. Graphical Abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-022-05405-5.
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Affiliation(s)
- Shan-Shan Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - De-Liang Tao
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jin-Ming Chen
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jiang-Ping Wu
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Xin Yang
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Jun-Ke Song
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, Shaanxi, China
| | - Xing-Quan Zhu
- College of Veterinary Medicine, Shanxi Agricultural University, Taigu, 030801, Shanxi, China. .,Key Laboratory of Veterinary Public Health of Higher Education of Yunnan Province, College of Veterinary Medicine, Yunnan Agricultural University, Kunming, 650201, Yunnan, China.
| | - Guang-Hui Zhao
- College of Veterinary Medicine, Northwest A&F University, Yangling, 712100, Shaanxi, China.
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Duan T, Du Y, Xing C, Wang HY, Wang RF. Toll-Like Receptor Signaling and Its Role in Cell-Mediated Immunity. Front Immunol 2022. [PMID: 35309296 DOI: 10.3389/fimmu.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023] Open
Abstract
Innate immunity is the first defense system against invading pathogens. Toll-like receptors (TLRs) are well-defined pattern recognition receptors responsible for pathogen recognition and induction of innate immune responses. Since their discovery, TLRs have revolutionized the field of immunology by filling the gap between the initial recognition of pathogens by innate immune cells and the activation of the adaptive immune response. TLRs critically link innate immunity to adaptive immunity by regulating the activation of antigen-presenting cells and key cytokines. Furthermore, recent studies also have shown that TLR signaling can directly regulate the T cell activation, growth, differentiation, development, and function under diverse physiological conditions. This review provides an overview of TLR signaling pathways and their regulators and discusses how TLR signaling, directly and indirectly, regulates cell-mediated immunity. In addition, we also discuss how TLR signaling is critically important in the host's defense against infectious diseases, autoimmune diseases, and cancer.
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Affiliation(s)
- Tianhao Duan
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Yang Du
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Changsheng Xing
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Helen Y Wang
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.,Department of Pediatrics, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Rong-Fu Wang
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.,Department of Pediatrics, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States.,Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
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Zhang X, Wang Y, Gong P, Wang X, Zhang N, Chen M, Wei R, Zhang X, Li X, Li J. Neospora caninum Evades Immunity via Inducing Host Cell Mitophagy to Inhibit Production of Proinflammatory Cytokines in a ROS-Dependent Manner. Front Immunol 2022; 13:827004. [PMID: 35355995 PMCID: PMC8959673 DOI: 10.3389/fimmu.2022.827004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/14/2022] [Indexed: 01/27/2023] Open
Abstract
Neospora caninum is an intracellular protozoan that mainly infects cattle to cause abortion and significant economic losses worldwide. A better understanding of the immune evasion mechanisms of N. caninum could help to search for an effective approach to prevent and treat neosporosis. Mitophagy is used by some viruses to evade host immune surveillance. However, host cell mitophagy and its effect on N. caninum infection is unclear. In the present study, N. caninum-induced host cell mitophagy and its role in parasite infection were investigated in vitro and in vivo. Furthermore, the regulation of N. caninum-induced host cell mitophagy on the production of Reactive Oxygen Species (ROS), the secretions of proinflammatory cytokines, and the signals of p38, ERK, and Nlrp3 inflammasome were explored. Our results showed that autophagosomes and co-localization of LC3 with mitochondria were observed in N. caninum-infected macrophages. The mtDNA/nDNA ratio and the levels of mitochondrial marker proteins (Hsp60 and Tim23) were decreased with the increase of N. caninum numbers or infection time. N. caninum could induce mitophagy in brain and peritoneal lavage fluid cells of mice. Promoting mitophagy via mitophagy inducers (CCCP) could shorten survival time, decrease body weight, increase parasite load, and attenuate secretion of cytokines in N. caninum infected mice. CCCP treatment decreased the production of cytokines and Reactive Oxygen Species (ROS), and increased parasite burden in N. caninum-infected macrophages. Furthermore, CCCP or NAC (ROS inhibitor) treatment could inhibit ERK signal, Nlrp3 inflammasome, and cytokine production, while promote p38 signal in N. caninum-infected macrophages. The opposite results were obtained when using a mitophagy inhibitor (Mdivi1). Taken together, N. caninum-induced mitophagy could regulate the activations of p38, ERK, Nlrp3 inflammasome to inhibit the production of inflammatory cytokines in a ROS-dependent manner to escape host immune surveillance.
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Affiliation(s)
- Xu Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Yuru Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Pengtao Gong
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xiaocen Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Nan Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Mengge Chen
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Ran Wei
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xichen Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xin Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jianhua Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
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Duan T, Du Y, Xing C, Wang HY, Wang RF. Toll-Like Receptor Signaling and Its Role in Cell-Mediated Immunity. Front Immunol 2022; 13:812774. [PMID: 35309296 PMCID: PMC8927970 DOI: 10.3389/fimmu.2022.812774] [Citation(s) in RCA: 185] [Impact Index Per Article: 92.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 02/08/2022] [Indexed: 12/13/2022] Open
Abstract
Innate immunity is the first defense system against invading pathogens. Toll-like receptors (TLRs) are well-defined pattern recognition receptors responsible for pathogen recognition and induction of innate immune responses. Since their discovery, TLRs have revolutionized the field of immunology by filling the gap between the initial recognition of pathogens by innate immune cells and the activation of the adaptive immune response. TLRs critically link innate immunity to adaptive immunity by regulating the activation of antigen-presenting cells and key cytokines. Furthermore, recent studies also have shown that TLR signaling can directly regulate the T cell activation, growth, differentiation, development, and function under diverse physiological conditions. This review provides an overview of TLR signaling pathways and their regulators and discusses how TLR signaling, directly and indirectly, regulates cell-mediated immunity. In addition, we also discuss how TLR signaling is critically important in the host's defense against infectious diseases, autoimmune diseases, and cancer.
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Affiliation(s)
- Tianhao Duan
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Yang Du
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Changsheng Xing
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Helen Y. Wang
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Department of Pediatrics, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Rong-Fu Wang
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Department of Pediatrics, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
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Wang J, Wang X, Gong P, Ren F, Li X, Zhang N, Zhang X, Zhang X, Li J. The Protective Role of TLR2 Mediates Impaired Autophagic Flux by Activating the mTOR Pathway During Neospora caninum Infection in Mice. Front Cell Infect Microbiol 2021; 11:788340. [PMID: 34900761 PMCID: PMC8662348 DOI: 10.3389/fcimb.2021.788340] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 11/05/2021] [Indexed: 11/20/2022] Open
Abstract
Autophagy has been shown to play an essential role in defending against intracellular bacteria, viruses, and parasites. Mounting evidence suggests that autophagy plays different roles in the infection process of different pathogens. Until now, there has been no conclusive evidence regarding whether host autophagy is involved in Neospora caninum infection. In the current study, we first monitored the activation of autophagy by N. caninum, which occurred mainly in the early stages of infection, and examined the role of host autophagy in N. caninum infection. Here, we presented evidence that N. caninum induced an increase in autophagic vesicles with double-membrane structures in macrophages at the early stage of infection. LC3-II expression peaked and decreased as infection continued. However, the expression of P62/SQSTM1 showed significant accumulation within 12 h of infection, indicating that autophagic flux was blocked. A tandem fluorescence protein mCherry-GFP-LC3 construct was used to corroborate the impaired autophagic flux. Subsequently, we found that N. caninum infection induced the activation of the TLR2–AKT–mTOR pathways. Further investigation revealed that TLR2–mTOR, accompanied by the blockade of autophagic flux, was responsible for impaired autophagy but was not associated with AKT. In vitro and in vivo, N. caninum replication was strongly blocked by the kinase inhibitor 3-methyladenine (3-MA, autophagy inhibitor). In contrast, rapamycin (Rapa, an autophagy inducer) was able to promote intracellular proliferation and reduce the survival rate of N. caninum-infected mice. On the other hand, the accumulation of autophagosomes facilitated the proliferation of N. caninum. Collectively, our findings suggest that activation of host autophagy facilitates N. caninum replication and may counteract the innate immune response of the host. In short, inhibition of the early stages of autophagy could potentially be a strategy for neosporosis control.
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Affiliation(s)
- Jielin Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China.,Graduate College, Jinzhou Medical University, Jinzhou, China
| | - Xiaocen Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Pengtao Gong
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Fu Ren
- Department of Anatomy, Shenyang Medical College, Shenyang, China
| | - Xin Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Nan Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xu Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Xichen Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Jianhua Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
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