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Ji C, Pan Y, Liu B, Liu J, Zhao C, Nie Z, Liao S, Kuang G, Wu X, Liu Q, Ning J, Tang Y, Fang L. Thioredoxin C of Streptococcus suis serotype 2 contributes to virulence by inducing antioxidative stress and inhibiting autophagy via the MSR1/PI3K-Akt-mTOR pathway in macrophages. Vet Microbiol 2024; 298:110263. [PMID: 39332163 DOI: 10.1016/j.vetmic.2024.110263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 09/18/2024] [Accepted: 09/21/2024] [Indexed: 09/29/2024]
Abstract
The thioredoxin (Trx) system plays a vital role in protecting against oxidative stress and ensures correct disulfide bonding to maintain protein function. Our previous research demonstrated that TrxA of Streptococcus suis Serotype 2 (SS2), a clinical strain from the lung of a diseased pig, contributes to virulence but is not involved in antioxidative stress. In this study, we identified another gene in the Trx family, TrxC, which encodes a protein of 104 amino acids with a CGDC active motif and 22.4 % amino acid sequence homology with TrxA. Unlike the TrxA, TrxC mutant strains were more susceptible to oxidative stresses induced by hydrogen peroxide and paraquat. In vitro experiments, the survival rate of the TrxC deletion mutant in RAW264.7 macrophages was only one-eighth of that of TrxA mutant strains. Transcriptome analysis revealed that autophagy-related genes were significantly upregulated in the TrxC mutant compared to those in the wild-type or TrxA mutant strains. Co-localization of LC3 puncta with TrxC was confirmed using laser confocal microscopy, and autophagy-related indicators were quantified using western blotting. Autophagy deficiency induced by ATG5 knockout significantly increased SS2 survival rate, especially in TrxC mutant strains. For the upstream signal regulation pathways, we found ΔTrxC strains regulate autophagy by activation of PI3K/Akt/mTOR signaling in RAW264.7 macrophages. In the Akt1-overexpressing cell line, ΔTrxC infection significantly decreased the autophagic response and promoted ΔTrxC mutant strain survival, while inhibition of Akt with MK2206 resulted in reduced ΔTrxC mutant strain survival and enhance the autophagic response. Furthermore, loss of TrxC increased the activity of MSR1, thereby inducing cellular autophagy and phagocytosis. Our data demonstrate that TrxC of SS2 contributes to virulence by inducing antioxidative stress and inhibits autophagy via the PI3K-Akt-mTOR pathway in macrophages, with MSR1 acting as a key factor in controlling infection.
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Affiliation(s)
- Chunxiao Ji
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410125, China
| | - Yanying Pan
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410125, China
| | - Bocheng Liu
- Hunan Institute of Animal and Veterinary Science, Changsha 410131, China
| | - Jianying Liu
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410125, China
| | - Chijun Zhao
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410125, China
| | - Zhuyuan Nie
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410125, China
| | - Simeng Liao
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
| | - Guangwei Kuang
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
| | - Xin Wu
- Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
| | - Quan Liu
- School of Life Science and Engineering, Foshan University, Guangdong 528225, China
| | - Jie Ning
- Department of Endocrinology, Shenzhen Longhua District Central Hospital, Shenzhen 518110, China
| | - Yulong Tang
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410125, China; Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
| | - Lihua Fang
- Department of Endocrinology, Shenzhen Longhua District Central Hospital, Shenzhen 518110, China; School of Life Science and Engineering, Foshan University, Guangdong 528225, China.
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Chen Y, Chen J, Xing Z, Peng C, Li D. Autophagy in Neuroinflammation: A Focus on Epigenetic Regulation. Aging Dis 2024; 15:739-754. [PMID: 37548945 PMCID: PMC10917535 DOI: 10.14336/ad.2023.0718-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 07/18/2023] [Indexed: 08/08/2023] Open
Abstract
Neuroinflammation, characterized by the secretion of abundant inflammatory mediators, pro-inflammatory polarization of microglia, and the recruitment of infiltrating myeloid cells to foci of inflammation, drives or exacerbates the pathological processes of central nervous system disorders, especially in neurodegenerative diseases. Autophagy plays an essential role in neuroinflammatory processes, and the underlaying physiological mechanisms are closely correlated with neuroinflammation-related signals. Inhibition of mTOR and activation of AMPK and FOXO1 enhance autophagy and thereby suppress NLRP3 inflammasome activity and apoptosis, leading to the relief of neuroinflammatory response. And autophagy mitigates neuroinflammation mainly manifested by promoting the polarization of microglia from a pro-inflammatory to an anti-inflammatory state, reducing the production of pro-inflammatory mediators, and up-regulating the levels of anti-inflammatory factors. Notably, epigenetic modifications are intimately associated with autophagy and the onset and progression of various brain diseases. Non-coding RNAs, including microRNAs, circular RNAs and long noncoding RNAs, and histone acetylation have been reported to adjust autophagy-related gene and protein expression to alleviate inflammation in neurological diseases. The present review primarily focuses on the role and mechanisms of autophagy in neuroinflammatory responses, as well as epigenetic modifications of autophagy in neuroinflammation to reveal potential therapeutic targets in central nervous system diseases.
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Affiliation(s)
- Yu Chen
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Junren Chen
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Ziwei Xing
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Cheng Peng
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
| | - Dan Li
- State Key Laboratory of Southwestern Chinese Medicine Resources, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, China
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Arutyunov A, Klein RS. Microglia at the scene of the crime: what their transcriptomics reveal about brain health. Curr Opin Neurol 2023; 36:207-213. [PMID: 37078646 PMCID: PMC10867866 DOI: 10.1097/wco.0000000000001151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/21/2023]
Abstract
PURPOSE OF REVIEW Microglia, which arise from primitive myeloid precursors that enter the central nervous system (CNS) during early development, are the first responders to any perturbance of homeostasis. Although their activation has become synonymous with neurologic disease, it remains unclear whether microglial responses are the cause of or response to neuropathology. Here, we review new insights in the roles of microglia during CNS health and disease, including preclinical studies that transcriptionally profile microglia to define their functional states. RECENT FINDINGS Converging evidence suggests that innate immune activation of microglia is associated with overlapping alterations in their gene expression profiles regardless of the trigger. Thus, recent studies examining neuroprotective microglial responses during infections and aging mirror those observed during chronic neurologic diseases, including neurodegeneration and stroke. Many of these insights derive from studies of microglial transcriptomes and function in preclinical models, some of which have been validated in human samples. During immune activation, microglia dismantle their homeostatic functions and transition into subsets capable of antigen presentation, phagocytosis of debris, and management of lipid homeostasis. These subsets can be identified during both normal and aberrant microglial responses, the latter of which may persist long-term. The loss of neuroprotective microglia, which maintain a variety of essential CNS functions, may therefore, in part, underlie the development of neurodegenerative diseases. SUMMARY Microglia exhibit a high level of plasticity, transforming into numerous subsets as they respond to innate immune triggers. Chronic loss of microglial homeostatic functions may underlie the development of diseases with pathological forgetting.
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Affiliation(s)
- Artem Arutyunov
- Center for Neuroimmunology & Neuroinfectious Diseases
- Departments of Medicine
| | - Robyn S. Klein
- Center for Neuroimmunology & Neuroinfectious Diseases
- Departments of Medicine
- Departments of Pathology & Immunology
- Departments of Neurosciences
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Wen Y, Chen Z, Tian Y, Yang M, Dong Q, Yang Y, Ding H. Incomplete autophagy promotes the proliferation of Mycoplasma hyopneumoniae through the JNK and Akt pathways in porcine alveolar macrophages. Vet Res 2022; 53:62. [PMID: 35927699 PMCID: PMC9351181 DOI: 10.1186/s13567-022-01074-5] [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: 02/11/2022] [Accepted: 06/24/2022] [Indexed: 11/10/2022] Open
Abstract
Autophagy is an important conserved homeostatic process related to nutrient and energy deficiency and organelle damage in diverse eukaryotic cells and has been reported to play an important role in cellular responses to pathogens and bacterial replication. The respiratory bacterium Mycoplasma hyopneumoniae has been identified to enter porcine alveolar macrophages, which are considered important immune cells. However, little is known about the role of autophagy in the pathogenesis of M. hyopneumoniae infection of porcine alveolar macrophages. Our experiments demonstrated that M. hyopneumoniae infection enhanced the formation of autophagosomes in porcine alveolar macrophages but prevented the fusion of autophagosomes with lysosomes, thereby blocking autophagic flux and preventing the acidification and destruction of M. hyopneumoniae in low-pH surroundings. In addition, using different autophagy regulators to intervene in the autophagy process, we found that incomplete autophagy promoted the intracellular proliferation of M. hyopneumoniae. We also found that blocking the phosphorylation of JNK and Akt downregulated the autophagy induced by M. hyopneumoniae, but pathways related to two mitogen-activated protein kinases (Erk1/2 and p38) did not affect the process. Collectively, M. hyopneumoniae induced incomplete autophagy in porcine alveolar macrophages through the JNK and Akt signalling pathways; conversely, incomplete autophagy prevented M. hyopneumoniae from entering and degrading lysosomes to realize the proliferation of M. hyopneumoniae in porcine alveolar macrophages. These findings raise the possibility that targeting the autophagic pathway may be effective for the prevention or treatment of M. hyopneumoniae infection.
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Affiliation(s)
- Yukang Wen
- Laboratory of Veterinary Mycoplasmology, College of Veterinary Medicine, Southwest University, Chongqing, 400715, China
| | - Zhengkun Chen
- Laboratory of Veterinary Mycoplasmology, College of Veterinary Medicine, Southwest University, Chongqing, 400715, China
| | - Yaqin Tian
- Laboratory of Veterinary Mycoplasmology, College of Veterinary Medicine, Southwest University, Chongqing, 400715, China
| | - Mei Yang
- Laboratory of Veterinary Mycoplasmology, College of Veterinary Medicine, Southwest University, Chongqing, 400715, China
| | - Qingshuang Dong
- Laboratory of Veterinary Mycoplasmology, College of Veterinary Medicine, Southwest University, Chongqing, 400715, China
| | - Yujiao Yang
- Laboratory of Veterinary Mycoplasmology, College of Veterinary Medicine, Southwest University, Chongqing, 400715, China
| | - Honglei Ding
- Laboratory of Veterinary Mycoplasmology, College of Veterinary Medicine, Southwest University, Chongqing, 400715, China.
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Epidemiology and Genetic Diversity of PCV2 Reveals That PCV2e Is an Emerging Genotype in Southern China: A Preliminary Study. Viruses 2022; 14:v14040724. [PMID: 35458454 PMCID: PMC9026887 DOI: 10.3390/v14040724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/24/2022] [Accepted: 03/27/2022] [Indexed: 11/17/2022] Open
Abstract
Porcine circovirus-associated disease (PCVAD), caused by porcine circovirus type 2 (PCV2), has ravaged the pig industry, causing huge economic loss. At present, PCV2b and PCV2d are highly prevalent genotypes worldwide, while in China, in addition to PCV2b and PCV2d, a newly emerged PCV2e genotype detected in the Fujian province has attracted attention, indicating that PCV2 genotypes in China are more abundant. A preliminary study was conducted to better understand the genetic diversity and prevalence of PCV2 genotypes in southern China. We collected 79 random lung samples from pigs with respiratory signs, from 2018 to 2021. We found a PCV2-positivity rate of 29.1%, and frequent co-infections of PCV2 with PCV3, Streptococcus suis (S. suis), and other porcine pathogens. All PCV2-positive samples were sequenced and subjected to whole-genome analysis. Phylogenetic analysis, based on the PCV2 ORF2 gene and complete genomes, found that PCV2 strains identified in this study belonged to genotypes PCV2a (1), PCV2b (6), PCV2d (10), and PCV2e (6). Importantly, PCV2e was identified for the first time in some provinces, including Guangdong and Jiangxi. Additionally, we found two positively selected sites in the ORF2 region, located on the previously reported antigenic epitopes. Moreover, codon 63, one of the positively selected sites, has different types of amino acids in different genotypes. In conclusion, this study shows that PCV2e is an emerging genotype circulating in southern China, which warrants urgent, specific surveillance to aid the development of prevention and control strategies in China.
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