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Liang Y, Wang H, Sun K, Sun J, Soong L. Lack of the IFN-γ signal leads to lethal Orientia tsutsugamushi infection in mice with skin eschar lesions. PLoS Pathog 2024; 20:e1012020. [PMID: 38743761 PMCID: PMC11125519 DOI: 10.1371/journal.ppat.1012020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 05/24/2024] [Accepted: 04/30/2024] [Indexed: 05/16/2024] Open
Abstract
Scrub typhus is an acute febrile disease due to Orientia tsutsugamushi (Ot) infection and can be life-threatening with organ failure, hemorrhage, and fatality. Yet, little is known as to how the host reacts to Ot bacteria at early stages of infection; no reports have addressed the functional roles of type I versus type II interferon (IFN) responses in scrub typhus. In this study, we used comprehensive intradermal (i.d.) inoculation models and two clinically predominant Ot strains (Karp and Gilliam) to uncover early immune events. Karp infection induced sequential expression of Ifnb and Ifng in inflamed skin and draining lymph nodes at days 1 and 3 post-infection. Using double Ifnar1-/-Ifngr1-/- and Stat1-/- mice, we found that deficiency in IFN/STAT1 signaling resulted in lethal infection with profound pathology and skin eschar lesions, which resembled to human scrub typhus. Further analyses demonstrated that deficiency in IFN-γ, but not IFN-I, resulted in impaired NK cell and macrophage activation and uncontrolled bacterial growth and dissemination, leading to metabolic dysregulation, excessive inflammatory cell infiltration, and exacerbated tissue damage. NK cells were found to be the major cellular source of innate IFN-γ, contributing to the initial Ot control in the draining lymph nodes. In vitro studies with dendritic cell cultures revealed a superior antibacterial effect offered by IFN-γ than IFN-β. Comparative in vivo studies with Karp- and Gilliam-infection revealed a crucial role of IFN-γ signaling in protection against progression of eschar lesions and Ot infection lethality. Additionally, our i.d. mouse models of lethal infection with eschar lesions are promising tools for immunological study and vaccine development for scrub typhus.
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Affiliation(s)
- Yuejin Liang
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Hui Wang
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Keer Sun
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jiaren Sun
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Lynn Soong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
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Minahan NT, Yen TY, Guo YLL, Shu PY, Tsai KH. Concatenated ScaA and TSA56 Surface Antigen Sequences Reflect Genome-Scale Phylogeny of Orientia tsutsugamushi: An Analysis Including Two Genomes from Taiwan. Pathogens 2024; 13:299. [PMID: 38668254 PMCID: PMC11054523 DOI: 10.3390/pathogens13040299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 03/29/2024] [Accepted: 03/29/2024] [Indexed: 04/29/2024] Open
Abstract
Orientia tsutsugamushi is an obligate intracellular bacterium associated with trombiculid mites and is the causative agent of scrub typhus, a life-threatening febrile disease. Strain typing of O. tsutsugamushi is based on its immunodominant surface antigen, 56-kDa type-specific antigen (TSA56). However, TSA56 gene sequence-based phylogenetic analysis is only partially congruent with core genome-based phylogenetic analysis. Thus, this study investigated whether concatenated surface antigen sequences, including surface cell antigen (Sca) proteins, can reflect the genome-scale phylogeny of O. tsutsugamushi. Complete genomes were obtained for two common O. tsutsugamushi strains in Taiwan, TW-1 and TW-22, and the core genome/proteome was identified for 11 O. tsutsugamushi strains. Phylogenetic analysis was performed using maximum likelihood (ML) and neighbor-joining (NJ) methods, and the congruence between trees was assessed using a quartet similarity measure. Phylogenetic analysis based on 691 concatenated core protein sequences produced identical tree topologies with ML and NJ methods. Among TSA56 and core Sca proteins (ScaA, ScaC, ScaD, and ScaE), TSA56 trees were most similar to the core protein tree, and ScaA trees were the least similar. However, concatenated ScaA and TSA56 sequences produced trees that were highly similar to the core protein tree, the NJ tree being more similar. Strain-level characterization of O. tsutsugamushi may be improved by coanalyzing ScaA and TSA56 sequences, which are also important targets for their combined immunogenicity.
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Affiliation(s)
- Nicholas T. Minahan
- Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taipei 100025, Taiwan; (N.T.M.); (Y.-L.L.G.)
| | - Tsai-Ying Yen
- Centers for Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taipei 115210, Taiwan; (T.-Y.Y.); (P.-Y.S.)
| | - Yue-Liang Leon Guo
- Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taipei 100025, Taiwan; (N.T.M.); (Y.-L.L.G.)
- Department of Environmental and Occupational Medicine, National Taiwan University (NTU) College of Medicine and NTU Hospital, Taipei 100025, Taiwan
| | - Pei-Yun Shu
- Centers for Diagnostics and Vaccine Development, Centers for Disease Control, Ministry of Health and Welfare, Taipei 115210, Taiwan; (T.-Y.Y.); (P.-Y.S.)
| | - Kun-Hsien Tsai
- Institute of Environmental and Occupational Health Sciences, College of Public Health, National Taiwan University, Taipei 100025, Taiwan; (N.T.M.); (Y.-L.L.G.)
- Global Health Program, College of Public Health, National Taiwan University, Taipei 100025, Taiwan
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Thiriot JD, Liang Y, Gonzales C, Sun J, Yu X, Soong L. Differential cellular immune responses against Orientia tsutsugamushi Karp and Gilliam strains following acute infection in mice. PLoS Negl Trop Dis 2023; 17:e0011445. [PMID: 38091346 PMCID: PMC10752558 DOI: 10.1371/journal.pntd.0011445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 12/27/2023] [Accepted: 12/06/2023] [Indexed: 12/28/2023] Open
Abstract
Scrub typhus is a leading cause of febrile illness in endemic countries due to infection with Orientia tsutsugamushi (Ot), a seriously understudied intracellular bacterium. Pulmonary involvement associated with vascular parasitism in patients is common and can develop into life threatening interstitial pneumonia. The diverse antigenicity of Ot genotypes and inter-strain differences in genome content are connected to varied virulence and clinical outcomes; however, detailed studies of strain-related pulmonary immune responses in human patients or small animal models of infection are lacking. In this study, we have used two clinically prevalent bacterial strains (Karp and Gilliam) to reveal cellular immune responses in inflamed lungs and potential biomarkers of disease severity. The results demonstrate that outbred CD-1 mice are highly susceptible to both Karp and Gilliam strains; however, C57BL/6 (B6) mice were susceptible to Karp, but resistant to Gilliam (with self-limiting infection), corresponding to their tissue bacterial burdens and lung pathological changes. Multicolor flow cytometric analyses of perfused B6 mouse lungs revealed robust and sustained influx and activation of innate immune cells (macrophages, neutrophils, and NK cells), followed by CD4+ and CD8+ T cells, during Karp infection, but such responses were greatly attenuated during Gilliam infection. The robust cellular responses in Karp-infected B6 mice positively correlated with significantly early and high levels of serum cytokine/chemokine protein levels (CXCL1, CCL2/3/5, and G-CSF), as well as pulmonary gene expression (Cxcl1/2, Ccl2/3/4, and Ifng). In vitro infection of B6 mouse-derived primary macrophages also revealed bacterial strain-dependent immune gene expression profiles. This study provided the lines of evidence that highlighted differential tissue cellular responses against Karp vs. Gilliam infection, offering a framework for future investigation of Ot strain-related mechanisms of disease pathogenesis vs. infection control.
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Affiliation(s)
- Joseph D. Thiriot
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Yuejin Liang
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infection and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Casey Gonzales
- Institute for Human Infection and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jiaren Sun
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infection and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Xiaoying Yu
- Department of Biostatistics & Data Science, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Lynn Soong
- Department of Microbiology & Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infection and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
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Liang Y, Aditi, Onyoni F, Wang H, Gonzales C, Sunyakumthorn P, Wu P, Samir P, Soong L. Brain transcriptomics reveal the activation of neuroinflammation pathways during acute Orientia tsutsugamushi infection in mice. Front Immunol 2023; 14:1194881. [PMID: 37426673 PMCID: PMC10326051 DOI: 10.3389/fimmu.2023.1194881] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 05/02/2023] [Indexed: 09/03/2023] Open
Abstract
Scrub typhus, an acute febrile illness caused by Orientia tsutsugamushi (Ot), is prevalent in endemic areas with one million new cases annually. Clinical observations suggest central nervous system (CNS) involvement in severe scrub typhus cases. Acute encephalitis syndrome (AES) associated with Ot infection is a major public health problem; however, the underlying mechanisms of neurological disorder remain poorly understood. By using a well-established murine model of severe scrub typhus and brain RNA-seq, we studied the brain transcriptome dynamics and identified the activated neuroinflammation pathways. Our data indicated a strong enrichment of several immune signaling and inflammation-related pathways at the onset of disease and prior to host death. The strongest upregulation of expression included genes involved in interferon (IFN) responses, defense response to bacteria, immunoglobulin-mediated immunity, IL-6/JAK-STAT signaling, and TNF signaling via NF-κB. We also found a significant increase in the expression of core genes related to blood-brain barrier (BBB) disruption and dysregulation in severe Ot infection. Brain tissue immunostaining and in vitro infection of microglia revealed microglial activation and proinflammatory cytokine production, suggesting a crucial role of microglia in neuroinflammation during scrub typhus. This study provides new insights into neuroinflammation in scrub typhus, highlighting the impact of excessive IFN responses, microglial activation, and BBB dysregulation on disease pathogenesis.
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Affiliation(s)
- Yuejin Liang
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
| | - Aditi
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Florence Onyoni
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
| | - Hui Wang
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Casey Gonzales
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Piyanate Sunyakumthorn
- Department of Veterinary Medicine, United States Army Medical Directorate, Armed Forces Research Institute of Medical Sciences (United States MD-AFRIMS), Bangkok, Thailand
| | - Ping Wu
- Department of Neuroscience, Cell Biology and Anatomy, University of Texas Medical Branch, Galveston, TX, United States
| | - Parimal Samir
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, United States
| | - Lynn Soong
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
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