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Li F, Song B, Zhou WF, Chu LJ. Toll-Like Receptors 7/8: A Paradigm for the Manipulation of Immunologic Reactions for Immunotherapy. Viral Immunol 2023; 36:564-578. [PMID: 37751284 DOI: 10.1089/vim.2023.0077] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023] Open
Abstract
The innate immune system recognizes conserved features of viral and microbial pathogens through pattern recognition receptors (PRRs). Toll-like receptors (TLRs) are one type of PRR used by the innate immune system to mediate the secretion of proinflammatory cytokines and promote innate and adaptive immune responses. TLR family members TLR7 and TLR8 (referred to as TLR7/8 from herein) are endosomal transmembrane receptors that recognize purine-rich single-stranded RNA (ssRNA) and bacterial DNA, eliciting an immunologic reaction to pathogens. TLR7/8 were discovered to mediate the secretion of proinflammatory cytokines by activating immune cells. In addition, accumulating evidence has indicated that TLR7/8 may be closely related to numerous immune-mediated disorders, specifically several types of cancer, autoimmune disease, and viral disease. TLR7/8 agonists and antagonists, which are used as drugs or adjuvants, have been identified in preclinical studies and clinical trials as promising immune stimulators for the immunotherapy of these immune-mediated disorders. These results provided reasoning to further explore immunotherapy for the treatment of immune-mediated disorders. Nevertheless, numerous needs remain unmet, and the therapeutic effects of TLR7/8 agonists and antagonists are poor and exert strong immune-related toxicities. The present review aimed to provide an overview of the TLR family members, particularly TLR7/8, and address the underlying molecular mechanisms and clinical implications of TLR7/8 in immune-mediated disorders. The aim of the work is to discuss the underlying molecular mechanisms and clinical implications of TLR7/8 in immune-mediated disorders.
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Affiliation(s)
- Fang Li
- Department of Clinical Medicine, Anhui Medical College, Hefei, China
| | - Biao Song
- Department of Pharmacy, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Wei-Feng Zhou
- Department of Clinical Medicine, Anhui Medical College, Hefei, China
| | - Li-Jin Chu
- Department of Clinical Medicine, Anhui Medical College, Hefei, China
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2
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Qiu H, Wang R, Xing J, Li L, Gao Z, Li J, Fang C, Shi F, Mo F, Liu L, Zhao Y, Xie H, Zhao S, Huang J. Characteristics of Th9 cells in Schistosoma japonicum-infected C57BL/6 mouse mesenteric lymph node. Mol Biochem Parasitol 2023; 254:111561. [PMID: 37086898 DOI: 10.1016/j.molbiopara.2023.111561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 04/17/2023] [Accepted: 04/19/2023] [Indexed: 04/24/2023]
Abstract
Interleukin 9 (IL-9) is an effective cytokine secreted by newly defined Th9 cells, which is involved in allergic and infectious diseases. In this study, lymphocytes were isolated from mesenteric lymph node (MLN), spleen, liver, lung, and Peyer's patches (PP) of C57BL/6 mice 5-6 weeks after S. japonicum infection, intracellular cytokine staining was done to detect the percentage of IL-9-producing CD4+ T cells. The qPCR and ELISA were used to verify the content of IL-9 in MLN. The population of IL-9-producing lymphocyte subset was identified by FACS. In addition, the dynamic changes and cytokine profiles of Th9 cells in the MLN of infected mice were detected by FACS. ELISA was used to detect IL-9 induced by soluble egg antigen (SEA) from isolated lymphocytes in mouse MLN. The results showed that the percentage of IL-9-secreting Th9 cells in the MLN of the infected mouse was higher than that in the spleen, liver, lung, or PP. Though CD8+ Tc cells, NKT cells, and γδT cells could secrete IL-9, CD4+ Th cells were the main source of IL-9 in S. japonicum-infected C57BL/6 mice (P < 0.05). The percentage of Th9 cells in MLN of infected mouse increased from week 3-4, and reached a peak at week 5-6, then began to decrease from week 7-8 (P < 0.05). Moreover, Th9 cells could also secrete a small amount of IL-4, IFN-γ, IL-5, and IL-10. Our results suggested a higher percentage of Th9 cells was induced in the MLN of S. japonicum-infected mice, which might play an important role in the early stage of S. japonicum-induced disease.
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Affiliation(s)
- Huaina Qiu
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Ruohan Wang
- The Second Clinical Medical College of Guangzhou University of Chinese Medicine, Guangzhou 510120, China
| | - Junmin Xing
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Lu Li
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Zhiyan Gao
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Jiajie Li
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Chao Fang
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Feihu Shi
- Department of Infectious Diseases, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China
| | - Feng Mo
- Department of Infectious Diseases, Guangdong Provincial Key Laboratory of Major Obstetric Diseases, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou 510150, China
| | - Lin Liu
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Yi Zhao
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China
| | - Hongyan Xie
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China.
| | - Shan Zhao
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China.
| | - Jun Huang
- China Sino-French Hoffmann Institute, Department of Basic Medical Science, Guangzhou Medical University, Guangzhou 511436, China.
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3
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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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4
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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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Liang L, Shen Y, Hu Y, Liu H, Cao J. cGAS exacerbates Schistosoma japonicum infection in a STING-type I IFN-dependent and independent manner. PLoS Pathog 2022; 18:e1010233. [PMID: 35108342 PMCID: PMC8809611 DOI: 10.1371/journal.ppat.1010233] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 12/23/2021] [Indexed: 12/17/2022] Open
Abstract
Schistosomiasis, which is caused by infection with Schistosoma spp., is characterized by granuloma and fibrosis in response to egg deposition. Pattern recognition receptors are important to sense invading Schistosoma, triggering an innate immune response, and subsequently shaping adaptive immunity. Cyclic GMP-AMP synthase (cGAS) was identified as a major cytosolic DNA sensor, which catalyzes the formation of cyclic GMP-AMP (cGAMP), a critical second messenger for the activation of the adaptor protein stimulator of interferon genes (STING). The engagement of STING by cGAMP leads to the activation of TANK-binding kinase 1 (TBK1), interferon regulatory factor 3 (IRF3), and the subsequent type I interferon (IFN) response. cGAS is suggested to regulate infectious diseases, autoimmune diseases, and cancer. However, the function of cGAS in helminth infection is unclear. In this study, we found that Cgas deficiency enhanced the survival of mice infected with S. japonicum markedly, without affecting the egg load in the liver. Consistently, Cgas deletion alleviated liver pathological impairment, reduced egg granuloma formation, and decreased fibrosis severity. In contrast, Sting deletion reduced the formation of egg granulomas markedly, but not liver fibrosis. Notably, Cgas or Sting deficiency reduced the production of IFNβ drastically in mice infected with S. japonicum. Intriguingly, intravenous administration of recombinant IFNβ exacerbated liver damage and promoted egg granuloma formation, without affecting liver fibrosis. Clodronate liposome-mediated depletion of macrophages indicated that macrophages are the major type of cells contributing to the induction of the type I IFN response during schistosome infection. Moreover, cGAS is important for type I IFN production and phosphorylation of TBK1 and IRF3 in response to stimulation with S. japonicum egg- or adult worm-derived DNA in macrophages. Our results clarified the immunomodulatory effect of cGAS in the regulation of liver granuloma formation during S. japonicum infection, involving sensing schistosome-derived DNA and producing type I IFN. Additionally, we showed that cGAS regulates liver fibrosis in a STING-type I–IFN-independent manner. The sensing of invading pathogens by pattern recognition receptors (PRRs) is important for the host to mount an immune response. Cytosolic DNA receptor cGAS has been documented as critical for the induction of innate immunity, manifesting as a type I IFN response. However, little is known about the role of cGAS or type I IFN in the process of helminth infection. In this study, we identified an important role of the cGAS-STING-type I IFN signaling axis in driving schistosome infection-induced liver inflammation. Moreover, we revealed a hitherto unknown role of cGAS in the regulation of liver fibrosis during Schistosoma infection, a process that is independent of STING. Our study revealed cGAS as a novel functional receptor for the recognition of invading Schistosoma, paving the way for the development of novel strategies to treat schistosomiasis.
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Affiliation(s)
- Le Liang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, (Chinese Center for Tropical Diseases Research); Key Laboratory of Parasite and Vector Biology, National Health Commission of People’s Republic of China; World Health Organization Collaborating Center for Tropical Diseases, Shanghai, China
- Shanghai University of Medicine & Health Sciences, Shanghai, China
- The School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yujuan Shen
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, (Chinese Center for Tropical Diseases Research); Key Laboratory of Parasite and Vector Biology, National Health Commission of People’s Republic of China; World Health Organization Collaborating Center for Tropical Diseases, Shanghai, China
- The School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuan Hu
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, (Chinese Center for Tropical Diseases Research); Key Laboratory of Parasite and Vector Biology, National Health Commission of People’s Republic of China; World Health Organization Collaborating Center for Tropical Diseases, Shanghai, China
- The School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Haipeng Liu
- Clinical and Translational Research Center, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
- Central Laboratory, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Jianping Cao
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, (Chinese Center for Tropical Diseases Research); Key Laboratory of Parasite and Vector Biology, National Health Commission of People’s Republic of China; World Health Organization Collaborating Center for Tropical Diseases, Shanghai, China
- The School of Global Health, Chinese Center for Tropical Diseases Research, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- * E-mail:
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Wei H, Xie H, Qu J, Xie A, Xie S, Huang H, Li J, Fang C, Shi F, Qiu H, Qi Y, Tian X, Yang Q, Huang J. TLR7 modulating B-cell immune responses in the spleen of C57BL/6 mice infected with Schistosoma japonicum. PLoS Negl Trop Dis 2021; 15:e0009943. [PMID: 34788282 PMCID: PMC8598019 DOI: 10.1371/journal.pntd.0009943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 10/21/2021] [Indexed: 11/19/2022] Open
Abstract
B cells played an important role in Schistosoma infection-induced diseases. TLR7 is an intracellular member of the innate immune receptor. The role of TLR7 on B cells mediated immune response is still unclear. Here, C57BL/6 mice were percutaneously infected by S. japonicum for 5-6 weeks. The percentages and numbers of B cells increased in the infected mice (p < 0.05), and many activation and function associated molecules were also changed on B cells. More splenic cells of the infected mice expressed TLR7, and B cells were served as the main cell population. Moreover, a lower level of soluble egg antigen (SEA) specific antibody and less activation associated molecules were found on the surface of splenic B cells from S. japonicum infected TLR7 gene knockout (TLR7 KO) mice compared to infected wild type (WT) mice (p < 0.05). Additionally, SEA showed a little higher ability in inducing the activation of B cells from naive WT mice than TLR7 KO mice (p < 0.05). Finally, the effects of TLR7 on B cells are dependent on the activation of NF-κB p65. Altogether, TLR7 was found modulating the splenic B cell responses in S. japonicum infected C57BL/6 mice.
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Affiliation(s)
- Haixia Wei
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Hongyan Xie
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Jiale Qu
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Anqi Xie
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Shihao Xie
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - He Huang
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Jiajie Li
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Chao Fang
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Feihu Shi
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Huaina Qiu
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Yanwei Qi
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Xu Tian
- Key Laboratory of Molecular Target & Clinical Pharmacology and the State Key Laboratory of Respiratory Disease, School of Pharmaceutical Sciences & The Fifth Affiliated Hospital, Guangzhou Medical University, Guangzhou, China
- * E-mail: (XT); (QY); (JH)
| | - Quan Yang
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- * E-mail: (XT); (QY); (JH)
| | - Jun Huang
- Key Laboratory of Immunology, State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
- China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
- * E-mail: (XT); (QY); (JH)
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7
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Feng Y, Xie H, Shi F, Chen D, Xie A, Li J, Fang C, Wei H, Huang H, Pan X, Tang X, Huang J. Roles of TLR7 in Schistosoma japonicum Infection-Induced Hepatic Pathological Changes in C57BL/6 Mice. Front Cell Infect Microbiol 2021; 11:754299. [PMID: 34692568 PMCID: PMC8531751 DOI: 10.3389/fcimb.2021.754299] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 09/10/2021] [Indexed: 12/11/2022] Open
Abstract
S. japonicum infection can induce granulomatous inflammation in the liver of the host. Granulomatous inflammation limits the spread of infection and plays a role in host protection. Toll-like receptor 7 (TLR7) is an endosomal TLR that recognizes single-stranded RNA (ssRNA). In this study, the role of TLR7 in S. japonicum infection-induced hepatitis was investigated in both normal and TLR7 knockout (KO) C57BL/6 mice. The results indicated that TLR7 KO could aggravate S. japonicum infection-induced damage in the body, with less granuloma formation in the tissue, lower WBCs in blood, and decreased ALT and AST in the serum. Then, the expression of TLR7 was detected in isolated hepatic lymphocytes. The results indicated that the percentage of TLR7+ cells was increased in the infected mice. Hepatic macrophages, DCs, and B cells could express TLR7, and most of the TLR7-expressing cells in the liver of infected mice were macrophages. The percentage of TLR7-expressing macrophages was also increased after infection. Moreover, macrophages, T cells, and B cells showed significant changes in the counts, activation-associated molecule expression, and cytokine secretion between S. japonicum-infected WT and TLR7 KO mice. Altogether, this study indicated that TLR7 could delay the progression of S. japonicum infection-induced hepatitis mainly through macrophages. DCs, B cells, and T cells were involved in the TLR7-mediated immune response.
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Affiliation(s)
- Yuanfa Feng
- Department of Infectious Diseases, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
| | - Hongyan Xie
- China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
| | - Feihu Shi
- Department of Infectious Diseases, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Dianhui Chen
- Department of Infectious Diseases, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.,China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
| | - Anqi Xie
- China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
| | - Jiajie Li
- China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
| | - Chao Fang
- China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
| | - Haixia Wei
- China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
| | - He Huang
- China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
| | - Xingfei Pan
- Department of Infectious Diseases, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China
| | - Xiaoping Tang
- Guangzhou Eighth People's Hospital, Guangzhou Medical University, Guangzhou, China
| | - Jun Huang
- China Sino-French Hoffmann Institute, Guangzhou Medical University, Guangzhou, China
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Abstract
The immune (innate and adaptive) system has evolved to protect the host from any danger present in the surrounding outer environment (microbes and associated MAMPs or PAMPs, xenobiotics, and allergens) and dangers originated within the host called danger or damage-associated molecular patterns (DAMPs) and recognizing and clearing the cells dying due to apoptosis. It also helps to lower the tissue damage during trauma and initiates the healing process. The pattern recognition receptors (PRRs) play a crucial role in recognizing different PAMPs or MAMPs and DAMPs to initiate the pro-inflammatory immune response to clear them. Toll-like receptors (TLRs) are first recognized PRRs and their discovery proved milestone in the field of immunology as it filled the gap between the first recognition of the pathogen by the immune system and the initiation of the appropriate immune response required to clear the infection by innate immune cells (macrophages, neutrophils, dendritic cells or DCs, and mast cells). However, in addition to their expression by innate immune cells and controlling their function, TLRs are also expressed by adaptive immune cells. We have identified 10 TLRs (TLR1-TLR10) in humans and 12 TLRs (TLR1-TLR13) in laboratory mice till date as TLR10 in mice is present only as a defective pseudogene. The present chapter starts with the introduction of innate immunity, timing of TLR evolution, and the evolution of adaptive immune system and its receptors (T cell receptors or TCRs and B cell receptors or BCRs). The next section describes the role of TLRs in the innate immune function and signaling involved in the generation of inflammation. The subsequent sections describe the expression and function of different TLRs in murine and human adaptive immune cells (B cells and different types of T cells, including CD4+T cells, CD8+T cells, CD4+CD25+Tregs, and CD8+CD25+Tregs, etc.). The modulation of TLRs expressed on T and B cells has a great potential to develop different vaccine candidates, adjuvants, immunotherapies to target various microbial infections, including current COVID-19 pandemic, cancers, and autoimmune and autoinflammatory diseases.
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Affiliation(s)
- Vijay Kumar
- Children's Health Queensland Clinical Unit, School of Clinical Medicine, Faculty of Medicine, Mater Research, University of Queensland, Brisbane, QLD, Australia.
- School of Biomedical Sciences, Faculty of Medicine, University of Queensland, Brisbane, QLD, Australia.
- Department of Pharmaceutical Sciences, College of Pharmacy, The University of Tennessee Health Science Center (UTHSC), Memphis, TN, USA.
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