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Moulden J, Sung CYW, Brizic I, Jonjic S, Britt W. Murine Models of Central Nervous System Disease following Congenital Human Cytomegalovirus Infections. Pathogens 2021; 10:1062. [PMID: 34451526 PMCID: PMC8400215 DOI: 10.3390/pathogens10081062] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 08/17/2021] [Accepted: 08/18/2021] [Indexed: 11/17/2022] Open
Abstract
Human cytomegalovirus infection of the developing fetus is a leading cause of neurodevelopmental disorders in infants and children, leading to long-term neurological sequela in a significant number of infected children. Current understanding of the neuropathogenesis of this intrauterine infection is limited because of the complexity of this infection, which includes maternal immunological responses that are overlaid on virus replication in the CNS during neurodevelopment. Furthermore, available data from human cases are observational, and tissues from autopsy studies have been derived from only the most severe infections. Animal models of this human infection are also limited by the strict species specificity of cytomegaloviruses. However, informative models including non-human primates and small animal models have been developed. These include several different murine models of congenital HCMV infection for the study of CMV neuropathogenesis. Although individual murine models do not completely recapitulate all aspects of the human infection, each model has provided significant information that has extended current understanding of the neuropathogenesis of this human infection. This review will compare and contrast different murine models in the context of available information from human studies of CNS disease following congenital HCMV infections.
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Affiliation(s)
- Jerome Moulden
- Department of Microbiology, UAB School of Medicine, Birmingham, Al 35294, USA;
| | - Cathy Yea Won Sung
- Laboratory of Hearing Biology and Therapeutics, NIDCD, NIH, Bethesda, MD 20892, USA;
| | - Ilija Brizic
- Center for Proteomics and Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (I.B.); (S.J.)
| | - Stipan Jonjic
- Center for Proteomics and Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, 51000 Rijeka, Croatia; (I.B.); (S.J.)
| | - William Britt
- Department of Microbiology, UAB School of Medicine, Birmingham, Al 35294, USA;
- Department of Pediatrics and Neurobiology, UAB School of Medicine, Birmingham, Al 35294, USA
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Chauhan P, Lokensgard JR. Glial Cell Expression of PD-L1. Int J Mol Sci 2019; 20:ijms20071677. [PMID: 30987269 PMCID: PMC6479336 DOI: 10.3390/ijms20071677] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 03/27/2019] [Accepted: 04/02/2019] [Indexed: 12/11/2022] Open
Abstract
The programmed death (PD)-1/PD-L1 pathway is a well-recognized negative immune checkpoint that results in functional inhibition of T-cells. Microglia, the brain-resident immune cells are vital for pathogen detection and initiation of neuroimmune responses. Moreover, microglial cells and astrocytes govern the activity of brain-infiltrating antiviral T-cells through upregulation of PD-L1 expression. While T-cell suppressive responses within brain are undoubtedly beneficial to the host, preventing cytotoxic damage to this vital organ, establishment of a prolonged anti-inflammatory milieu may simultaneously lead to deficiencies in viral clearance. An immune checkpoint blockade targeting the PD-1: PD-L1 (B7-H1; CD274) axis has revolutionized contemporary treatment for a variety of cancers. However, the therapeutic potential of PD1: PD-L1 blockade therapies targeting viral brain reservoirs remains to be determined. For these reasons, it is key to understand both the detrimental and protective functions of this signaling pathway within the brain. This review highlights how glial cells use PD-L1 expression to modulate T-cell effector function and limit detrimental bystander damage, while still retaining an effective defense of the brain.
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Affiliation(s)
- Priyanka Chauhan
- Neurovirology Laboratory, Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA.
| | - James R Lokensgard
- Neurovirology Laboratory, Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA.
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Brizić I, Hiršl L, Šustić M, Golemac M, Britt WJ, Krmpotić A, Jonjić S. CD4 T cells are required for maintenance of CD8 T RM cells and virus control in the brain of MCMV-infected newborn mice. Med Microbiol Immunol 2019; 208:487-494. [PMID: 30923899 DOI: 10.1007/s00430-019-00601-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 03/19/2019] [Indexed: 02/07/2023]
Abstract
Cytomegalovirus (CMV) infection is a significant public health problem. Congenital CMV infection is a leading infectious cause of long-term neurodevelopmental sequelae, including mental retardation and sensorineural hearing loss. Immune protection against mouse cytomegalovirus (MCMV) is primarily mediated by NK cells and CD8+ T cells, while CD4+ T cells are not needed for control of MCMV in majority of organs in immunocompetent adult mice. Here, we set out to determine the role of CD4+ T cells upon MCMV infection of newborn mice. We provide evidence that CD4+ T cells are essential for clearance of MCMV infection in brain of neonatal mice and for prevention of recurrence of latent MCMV. In addition, we provide evidence that CD4+ T cells are required for induction and maintenance of tissue-resident memory CD8+ T cells in the brain of mice perinatally infected with MCMV.
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Affiliation(s)
- Ilija Brizić
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, B. Branchetta 20, 51000, Rijeka, Croatia.,Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Lea Hiršl
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, B. Branchetta 20, 51000, Rijeka, Croatia.,Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Marko Šustić
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, B. Branchetta 20, 51000, Rijeka, Croatia
| | - Mijo Golemac
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, B. Branchetta 20, 51000, Rijeka, Croatia
| | - William J Britt
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Astrid Krmpotić
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, B. Branchetta 20, 51000, Rijeka, Croatia
| | - Stipan Jonjić
- Department of Histology and Embryology, Faculty of Medicine, University of Rijeka, B. Branchetta 20, 51000, Rijeka, Croatia. .,Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia.
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Lokensgard JR, Mutnal MB, Prasad S, Sheng W, Hu S. Glial cell activation, recruitment, and survival of B-lineage cells following MCMV brain infection. J Neuroinflammation 2016; 13:114. [PMID: 27207308 PMCID: PMC4874004 DOI: 10.1186/s12974-016-0582-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 05/13/2016] [Indexed: 12/23/2022] Open
Abstract
Background Chemokines produced by reactive glia drive migration of immune cells and previous studies from our laboratory have demonstrated that CD19+ B cells infiltrate the brain. In this study, in vivo and in vitro experiments investigated the role of reactive glial cells in recruitment and survival of B-lineage cells in response to (murine cytomegalovirus) MCMV infection. Methods Flow cytometric analysis was used to assess chemokine receptor expression on brain-infiltrating B cells. Real-time RT-PCR and ELISA were used to measure chemokine levels. Dual-immunohistochemical staining was used to co-localize chemokine production by reactive glia. Primary glial cell cultures and migration assays were used to examine chemokine-mediated recruitment. Astrocyte: B cell co-cultures were used to investigate survival and proliferation. Results The chemokine receptors CXCR3, CXCR5, CCR5, and CCR7 were detected on CD19+ cells isolated from the brain during MCMV infection. In particular, CXCR3 was found to be elevated on an increasing number of cells over the time course of infection, and it was the primary chemokine receptor expressed at 60 days post infection Quite different expression kinetics were observed for CXCR5, CCR5, and CCR7, which were elevated on the highest number of cells early during infection and decreased by 14, 30, and 60 days post infection Correspondingly, elevated levels of CXCL9, CXCL10, and CXCL13, as well as CCL5, were found within the brains of infected animals, and only low levels of CCL3 and CCL19 were detected. Differential expression of CXCL9/CXCL10 and CXCL13 between microglia and astrocytes was apparent, and B cells moved towards supernatants from MCMV-infected microglia, but not astrocytes. Pretreatment with neutralizing Abs to CXCL9 and CXCL10 inhibited this migration. In contrast, neutralizing Abs to the ligand of CXCR5 (i.e., CXCL13) did not significantly block chemotaxis. Proliferation of brain-infiltrating B cells was detected at 7 days post infection and persisted through the latest time tested (60 days post infection). Finally, astrocytes produce BAFF (B cell activating factor of the TNF family) and promote proliferation of B cells via cell-to-cell contact. Conclusions CXCR3 is the primary chemokine receptor on CD19+ B cells persisting within the brain, and migration to microglial cell supernatants is mediated through this receptor. Correspondingly, microglial cells produce CXCL9 and CXCL10, but not CXCL13. Reactive astrocytes promote B cell proliferation.
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Affiliation(s)
- James R Lokensgard
- Neurovirology Laboratory, Department of Medicine, University of Minnesota, 3-220 LRB/MTRF, 2001 6th Street S.E., Minneapolis, MN, 55455, USA.
| | - Manohar B Mutnal
- Neurovirology Laboratory, Department of Medicine, University of Minnesota, 3-220 LRB/MTRF, 2001 6th Street S.E., Minneapolis, MN, 55455, USA
| | - Sujata Prasad
- Neurovirology Laboratory, Department of Medicine, University of Minnesota, 3-220 LRB/MTRF, 2001 6th Street S.E., Minneapolis, MN, 55455, USA
| | - Wen Sheng
- Neurovirology Laboratory, Department of Medicine, University of Minnesota, 3-220 LRB/MTRF, 2001 6th Street S.E., Minneapolis, MN, 55455, USA
| | - Shuxian Hu
- Neurovirology Laboratory, Department of Medicine, University of Minnesota, 3-220 LRB/MTRF, 2001 6th Street S.E., Minneapolis, MN, 55455, USA
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Prasad S, Hu S, Sheng WS, Singh A, Lokensgard JR. Tregs Modulate Lymphocyte Proliferation, Activation, and Resident-Memory T-Cell Accumulation within the Brain during MCMV Infection. PLoS One 2015; 10:e0145457. [PMID: 26720146 PMCID: PMC4697843 DOI: 10.1371/journal.pone.0145457] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 12/03/2015] [Indexed: 11/25/2022] Open
Abstract
Accumulation and retention of regulatory T-cells (Tregs) has been reported within post viral-encephalitic brains, however, the full extent to which these cells modulate neuroinflammation is yet to be elucidated. Here, we used Foxp3-DTR (diphtheria toxin receptor) knock-in transgenic mice, which upon administration of low dose diphtheria toxin (DTx) results in specific deletion of Tregs. We investigated the proliferation status of various immune cell subtypes within inflamed central nervous system (CNS) tissue. Depletion of Tregs resulted in increased proliferation of both CD8+ and CD4+ T-cell subsets within the brain at 14 d post infection (dpi) when compared to Treg-sufficient animals. At 30 dpi, while proliferation of CD8+ T-cells was controlled within brains of both Treg-depleted and undepleted mice, proliferation of CD4+ T-cells remained significantly enhanced with DTx-treatment. Previous studies have demonstrated that Treg numbers within the brain rebound following DTx treatment to even higher numbers than in untreated animals. Despite this rebound, CD8+ and CD4+ T-cells proliferated at a higher rate when compared to that of Treg-sufficient mice, thus maintaining sustained neuroinflammation. Furthermore, at 30 dpi we found the majority of CD8+ T-cells were CD127hi KLRG1- indicating that the cells were long lived memory precursor cells. These cells showed marked elevation of CD103 expression, a marker of tissue resident-memory T-cells (TRM) in the CNS, in untreated animals when compared to DTx-treated animals suggesting that generation of TRM is impaired upon Treg depletion. Moreover, the effector function of TRM as indicated by granzyme B production in response to peptide re-stimulation was found to be more potent in Treg-sufficient animals. Taken together, our findings demonstrate that Tregs limit neuroinflammatory responses to viral infection by controlling cell proliferation and may direct a larger proportion of lymphocytes within the brain to be maintained as TRM cells.
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Affiliation(s)
- Sujata Prasad
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, 55455, United States of America
| | - Shuxian Hu
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, 55455, United States of America
| | - Wen S. Sheng
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, 55455, United States of America
| | - Amar Singh
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, 55455, United States of America
| | - James R. Lokensgard
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, 55455, United States of America
- * E-mail:
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Lokensgard JR, Schachtele SJ, Mutnal MB, Sheng WS, Prasad S, Hu S. Chronic reactive gliosis following regulatory T cell depletion during acute MCMV encephalitis. Glia 2015; 63:1982-1996. [PMID: 26041050 DOI: 10.1002/glia.22868] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 05/12/2015] [Indexed: 12/21/2022]
Abstract
Long-term, persistent central nervous system inflammation is commonly seen following brain infection. Using a murine model of viral encephalitis (murine cytomegalovirus, MCMV) we have previously shown that post-encephalitic brains are maintained in an inflammatory state consisting of glial cell reactivity, retention of brain-infiltrating tissue-resident memory CD8+ T-cells, and long-term persistence of antibody-producing cells of the B-lineage. Here, we report that this neuroinflammation occurs concomitantly with accumulation and retention of immunosuppressive regulatory T-cells (Tregs), and is exacerbated following their ablation. However, the extent to which these Tregs function to control neuroimmune activation following MCMV encephalitis is unknown. In this study, we used Foxp3-diphtheria toxin receptor-GFP (Foxp3-DTR-GFP) transgenic mice, which upon administration of low-dose diphtheria toxin (DTx) results in the specific depletion of Tregs, to investigate their function. We found treatment with DTx during the acute phase of viral brain infection (0-4 dpi) resulted in depletion of Tregs from the brain, exacerbation of encephalitis (i.e., increased presence of CD4+ and CD8+ T-cells), and chronic reactive phenotypes of resident glial cells (i.e., elevated MHC Class II as well as PD-L1 levels, sustained microgliosis, and increased glial fibrillary acidic protein (GFAP) expression on astrocytes) versus untreated, infected animals. This chronic proinflammatory environment was associated with reduced cognitive performance in spatial learning and memory tasks (Barnes Maze) by convalescent animals. These data demonstrate that chronic glial cell activation, unremitting post-encephalitic neuroinflammation, and its associated long-term neurological sequelae in response to viral brain infection are modulated by the immunoregulatory properties of Tregs. GLIA 2015;63:1982-1996.
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Affiliation(s)
- James R Lokensgard
- Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Scott J Schachtele
- Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Manohar B Mutnal
- Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Wen S Sheng
- Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Sujata Prasad
- Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Shuxian Hu
- Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
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Mutnal MB, Hu S, Schachtele SJ, Lokensgard JR. Infiltrating regulatory B cells control neuroinflammation following viral brain infection. THE JOURNAL OF IMMUNOLOGY 2014; 193:6070-80. [PMID: 25385825 DOI: 10.4049/jimmunol.1400654] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Previous studies have demonstrated the existence of a subset of B lymphocytes, regulatory B cells (Bregs), which modulate immune function. In this study, in vivo and in vitro experiments were undertaken to elucidate the role of these Bregs in controlling neuroinflammation following viral brain infection. We used multicolor flow cytometry to phenotype lymphocyte subpopulations infiltrating the brain, along with in vitro cocultures to assess their anti-inflammatory and immunoregulatory roles. This distinctive subset of CD19(+)CD1d(hi)CD5(+) B cells was found to infiltrate the brains of chronically infected animals, reaching highest levels at the latest time point tested (30 d postinfection). B cell-deficient Jh(-/-) mice were found to develop exacerbated neuroimmune responses as measured by enhanced accumulation and/or retention of CD8(+) T cells within the brain, as well as increased levels of microglial activation (MHC class II). Conversely, levels of Foxp3(+) regulatory T cells were found to be significantly lower in Jh(-/-) mice when compared with wild-type (Wt) animals. Further experiments showed that in vitro-generated IL-10-secreting Bregs (B10) were able to inhibit cytokine responses from microglia following stimulation with viral Ags. These in vitro-generated B10 cells were also found to promote proliferation of regulatory T cells in coculture studies. Finally, gain-of-function experiments demonstrated that reconstitution of Wt B cells into Jh(-/-) mice restored neuroimmune responses to levels exhibited by infected Wt mice. Taken together, these results demonstrate that Bregs modulate T lymphocyte as well as microglial cell responses within the infected brain and promote CD4(+)Foxp3(+) T cell proliferation in vitro.
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Affiliation(s)
- Manohar B Mutnal
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, MN 55455
| | - Shuxian Hu
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, MN 55455
| | - Scott J Schachtele
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, MN 55455
| | - James R Lokensgard
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, Department of Medicine, University of Minnesota, Minneapolis, MN 55455
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Slavuljica I, Kveštak D, Huszthy PC, Kosmac K, Britt WJ, Jonjić S. Immunobiology of congenital cytomegalovirus infection of the central nervous system—the murine cytomegalovirus model. Cell Mol Immunol 2014; 12:180-91. [PMID: 25042632 DOI: 10.1038/cmi.2014.51] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/02/2014] [Indexed: 02/05/2023] Open
Abstract
Congenital human cytomegalovirus infection is a leading infectious cause of long-term neurodevelopmental sequelae, including mental retardation and hearing defects. Strict species specificity of cytomegaloviruses has restricted the scope of studies of cytomegalovirus infection in animal models. To investigate the pathogenesis of congenital human cytomegalovirus infection, we developed a mouse cytomegalovirus model that recapitulates the major characteristics of central nervous system infection in human infants, including the route of neuroinvasion and neuropathological findings. Following intraperitoneal inoculation of newborn animals with mouse cytomegalovirus, the virus disseminates to the central nervous system during high-level viremia and replicates in the brain parenchyma, resulting in a focal but widespread, non-necrotizing encephalitis. Central nervous system infection is coupled with the recruitment of resident and peripheral immune cells as well as the expression of a large number of pro-inflammatory cytokines. Although infiltration of cellular constituents of the innate immune response characterizes the early immune response in the central nervous system, resolution of productive infection requires virus-specific CD8(+) T cells. Perinatal mouse cytomegalovirus infection results in profoundly altered postnatal development of the mouse central nervous system and long-term motor and sensory disabilities. Based on an enhanced understanding of the pathogenesis of this infection, prospects for novel intervention strategies aimed to improve the outcome of congenital human cytomegalovirus infection are proposed.
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Affiliation(s)
- Irena Slavuljica
- 1] Department of Histology and Embryology, School of Medicine, University of Rijeka, Rijeka, Croatia [2] Department of Infectious Diseases, School of Medicine, University of Rijeka, Rijeka, Croatia
| | - Daria Kveštak
- Department of Histology and Embryology, School of Medicine, University of Rijeka, Rijeka, Croatia
| | - Peter Csaba Huszthy
- 1] Department of Histology and Embryology, School of Medicine, University of Rijeka, Rijeka, Croatia [2] Department of Immunology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Kate Kosmac
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - William J Britt
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Stipan Jonjić
- Department of Histology and Embryology, School of Medicine, University of Rijeka, Rijeka, Croatia
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Mutnal MB, Hu S, Lokensgard JR. Persistent humoral immune responses in the CNS limit recovery of reactivated murine cytomegalovirus. PLoS One 2012; 7:e33143. [PMID: 22412996 PMCID: PMC3295797 DOI: 10.1371/journal.pone.0033143] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Accepted: 02/10/2012] [Indexed: 12/17/2022] Open
Abstract
Background Experimental infection of the mouse brain with murine CMV (MCMV) elicits neuroimmune responses that terminate acute infection while simultaneously preventing extensive bystander damage. Previous studies have determined that CD8+ T lymphocytes are required to restrict acute, productive MCMV infection within the central nervous system (CNS). In this study, we investigated the contribution of humoral immune responses in control of MCMV brain infection. Methodology/Principal Findings Utilizing our MCMV brain infection model, we investigated B-lymphocyte-lineage cells and assessed their role in controlling the recovery of reactivated virus from latently infected brain tissue. Brain infiltrating leukocytes were first phenotyped using markers indicative of B-lymphocytes and plasma cells. Results obtained during these studies showed a steady increase in the recruitment of B-lymphocyte-lineage cells into the brain throughout the time-course of viral infection. Further, MCMV-specific antibody secreting cells (ASC) were detected within the infiltrating leukocyte population using an ELISPOT assay. Immunohistochemical studies of brain sections revealed co-localization of CD138+ cells with either IgG or IgM. Additional immunohistochemical staining for MCMV early antigen 1 (E1, m112–113), a reported marker of viral latency in neurons, confirmed its expression in the brain during latent infection. Finally, using B-cell deficient (Jh−/−) mice we demonstrated that B-lymphocytes control recovery of reactivated virus from latently-infected brain tissue. A significantly higher rate of reactivated virus was recovered from the brains of Jh−/− mice when compared to Wt animals. Conclusion Taken together, these results demonstrate that MCMV infection triggers accumulation and persistence of B-lymphocyte-lineage cells within the brain, which produce antibodies and play a significant role in controlling reactivated virus.
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Affiliation(s)
- Manohar B Mutnal
- Neuroimmunology Laboratory, Department of Medicine, Center for Infectious Diseases and Microbiology Translational Research, University of Minnesota, Minnesota, United States of America
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Memory T cells persisting in the brain following MCMV infection induce long-term microglial activation via interferon-γ. J Neurovirol 2011; 17:424-37. [PMID: 21800103 DOI: 10.1007/s13365-011-0042-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 06/14/2011] [Accepted: 06/22/2011] [Indexed: 10/17/2022]
Abstract
Murine cytomegalovirus (MCMV) brain infection stimulates microglial cell-driven proinflammatory chemokine production which precedes the presence of brain-infiltrating systemic immune cells. Here, we show that in response to MCMV brain infection, antigen-specific CD8(+) T cells migrated into the brain and persisted as long-lived memory cells. The role of these persistent T cells in the brain is unclear because most of our understanding of antimicrobial T cell responses comes from analyses of lymphoid tissue. Strikingly, memory T cells isolated from the brain exhibited an effector phenotype and produced IFN-γ upon restimulation with viral peptide. Furthermore, we observed time-dependent and long-term activation of resident microglia, indicated by chronic MHC class II up-regulation and TNF-α production. The immune response in this immunologically restricted site persisted in the absence of active viral replication. Lymphocyte infiltrates were detected until 30 days post-infection (p.i.), with CD8(+) and CD4(+) T cells present at a 3:1 ratio, respectively. We then investigated the role of IFN-γ in chronic microglial activation by using IFN-γ-knockout (GKO) mice. At 30 days p.i., GKO mice demonstrated a similar phenotypic brain infiltrate when compared to wild-type mice (Wt), however, MHC class II expression on microglia isolated from these GKO mice was significantly lower compared to Wt animals. When IFN-γ producing CD8(+) T cells were reconstituted in GKO mice, MHC class II up-regulation on microglial cells was restored. Taken together, these results suggest that MCMV brain infection results in long-term persistence of antigen-specific CD8(+) T cells which produce IFN-γ and drive chronic microglial cell activation. This response was found to be dependent on IFN-γ production by viral Ag-specific T cells during the chronic phase of disease.
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Cheeran MCJ, Mutnal MB, Hu S, Armien A, Lokensgard JR. Reduced lymphocyte infiltration during cytomegalovirus brain infection of interleukin-10-deficient mice. J Neurovirol 2010; 15:334-42. [PMID: 19626525 DOI: 10.1080/13550280903062797] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Interleukin (IL)-10 deficiency results in highly elevated levels of interferon (IFN)-gamma, as well as the IFN-gamma-inducible chemokines CXCL9 and CXCL10 within murine cytomegalovirus (MCMV)-infected brains. To test the hypothesis that these elevated chemokine levels would result in enhanced brain infiltration, we compared immune cell infiltration in response to MCMV brain infection between wild-type and IL-10 knockout (KO) mice. Longitudinal analysis following adoptive transfer of cells from beta-actin-luciferase transgenic wild-type mice showed maximal brain infiltration by peripheral immune cells occurred at 5 days post infection. Although the overall percentage of CD45(hi) cells infiltrating the brain was not altered by IL-10 deficiency, paradoxically, despite elevated chemokine levels, reduced T lymphocyte (CD8+) and natural killer (NK) (CD49b+) cell infiltration into the brain was observed in IL-10-deficient animals. This decreased lymphocyte infiltration was associated with elevated levels of the lymph node homing receptor L-selectin/CD62L on CD8+ T cells. Lymph node cells obtained from MCMV-infected mice deficient in IL-10 also displayed reduced migration towards CXCL10 when compared to wild-type animals. Taken together, these data show that despite elevated chemokine levels, absence of IL-10 results in reduced lymphocyte infiltration into MCMV-infected brains.
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Affiliation(s)
- Maxim C-J Cheeran
- Center for Infectious Diseases and Microbiology Translational Research, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
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Neuropathogenesis of congenital cytomegalovirus infection: disease mechanisms and prospects for intervention. Clin Microbiol Rev 2009; 22:99-126, Table of Contents. [PMID: 19136436 DOI: 10.1128/cmr.00023-08] [Citation(s) in RCA: 316] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Congenital cytomegalovirus (CMV) infection is the leading infectious cause of mental retardation and hearing loss in the developed world. In recent years, there has been an improved understanding of the epidemiology, pathogenesis, and long-term disabilities associated with CMV infection. In this review, current concepts regarding the pathogenesis of neurological injury caused by CMV infections acquired by the developing fetus are summarized. The pathogenesis of CMV-induced disabilities is considered in the context of the epidemiology of CMV infection in pregnant women and newborn infants, and the clinical manifestations of brain injury are reviewed. The prospects for intervention, including antiviral therapies and vaccines, are summarized. Priorities for future research are suggested to improve the understanding of this common and disabling illness of infancy.
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Cheeran MCJ, Jiang Z, Hu S, Ni HT, Palmquist JM, Lokensgard JR. Cytomegalovirus infection and interferon-gamma modulate major histocompatibility complex class I expression on neural stem cells. J Neurovirol 2008; 14:437-47. [PMID: 18937121 DOI: 10.1080/13550280802356845] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Cytomegalovirus (CMV) is the leading transmittable cause of congenital brain abnormalities in children and infection results in fatal ventriculoencephalitis in advanced acquired immunodeficiency syndrome (AIDS) patients. Pathology associated with CMV brain infection is seen predominantly in the periventricular region, an area known to harbor neural stem cells (NSCs). In the present study, using an adult model of murine CMV brain infection, the authors demonstrated that nestin-positive NSCs in the subventricular zone are susceptible to murine CMV infection. Furthermore, primary NSC cultures supported productive murine CMV replication with a 1000-fold increase in viral titers by 5 days post infection (d.p.i). Previous studies from the authors' laboratory demonstrated that CD8 lymphocytes were essential in protecting the brain against murine CMV infection. In the present study, the authors found that interferon (IFN)-gamma treatment increased the expression of major histocompatibility complex (MHC) class I on NSCs. Viral infection, on the other hand, inhibited this IFN-gamma-induced MHC up-regulation. In addition to increasing MHC class I expression, IFN-gamma (but not tumor necrosis factor [TNF]-alpha, interleukin [IL]-1 beta, or IL-10) also suppressed NSC proliferation in vitro. This decrease in proliferation was not accompanied by apoptosis or extracellular release of cellular lactate dehydrogenase (LDH), suggesting that the effects were not due to direct cytotoxicity. These studies demonstrate that NSCs are susceptible to murine CMV infection and inflammatory mediators, such as IFN-gamma, alter cellular characteristics which may have an impact on their reparative functions.
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Affiliation(s)
- Maxim C-J Cheeran
- Neuroimmunology Laboratory, Center for Infectious Diseases and Microbiology Translational Research, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA.
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Xiong Z, Gharagozlou S, Vengco I, Chen W, Ohlfest JR. Effective CpG immunotherapy of breast carcinoma prevents but fails to eradicate established brain metastasis. Clin Cancer Res 2008; 14:5484-93. [PMID: 18765540 DOI: 10.1158/1078-0432.ccr-07-4139] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Breast cancer patients with brain metastasis have a dismal prognosis. We determined the ability of immunostimulatory CpG oligodeoxynucleotides (ODN) to treat or prevent brain metastasis in a mouse model. EXPERIMENTAL DESIGN Mice bearing orthotopic breast carcinoma with or without concurrent i.c. tumors were treated by injections of CpG ODN at the primary tumor. Immunologic memory was tested by tumor rechallenge and immune responses were assessed by flow cytometry, delayed-type hypersensitivity, and CTL assays. RESULTS Orthotopic tumors regressed in treated mice regardless of whether concurrent i.c. disease was present. In mice bearing only orthotopic tumors, CpG ODN rendered 50% tumor-free and they rejected tumor rechallenge in breast and brain. In mice with concurrent i.c. disease, there was no difference in brain tumor growth compared with saline controls, despite regression of the primary tumor. Flow cytometry revealed that treated mice that died from i.c. disease exhibited a significant increase in brain-infiltrating T and natural killer cells relative to saline controls. CTLs from these mice were able to kill tumor in vitro and extend survival of naive mice bearing less-established brain tumors by adoptive transfer. CONCLUSIONS The lack of survival benefit in mice with appreciable brain metastasis was not explained by a deficit in lymphocyte trafficking or function because CTLs from these mice killed tumor and inhibited microscopic brain metastasis by adoptive transfer. These results indicate that CpG ODN might be beneficial as a preventative adjuvant to initial therapy preceding brain metastasis or to inhibit progression of microscopic brain metastases.
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Affiliation(s)
- Zhengming Xiong
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
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15
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Cheeran MCJ, Hu S, Palmquist JM, Bakken T, Gekker G, Lokensgard JR. Dysregulated interferon-gamma responses during lethal cytomegalovirus brain infection of IL-10-deficient mice. Virus Res 2007; 130:96-102. [PMID: 17624463 PMCID: PMC2134841 DOI: 10.1016/j.virusres.2007.05.022] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 05/29/2007] [Accepted: 05/30/2007] [Indexed: 12/23/2022]
Abstract
Murine cytomegalovirus (MCMV) brain infection induces a transient increase in chemokine production, which precedes the infiltration of CD3(+) lymphocytes. In this study, we hypothesized that an absence of anti-inflammatory cytokines would result in sustained proinflammatory neuroimmune responses. Direct intracerebroventricular injection of MCMV into IL-10 knockout (KO) mice produced an unexpected result: while wild-type animals controlled MCMV, the infection was lethal in IL-10 KO animals. Identical infection of IL-4 KO animals did not produce lethal disease. To further characterize the role of IL-10, infected brain tissue from both wild-type and IL-10 KO animals was assessed for cytokine and chemokine levels, as well as viral gene expression. These data show vastly elevated levels of interferon (IFN)-gamma, and the IFN-gamma-inducible chemokines CXCL9 and CXCL10, as well as IL-6 in brain homogenates obtained from IL-10 KO animals. However, MCMV viral load, glycoprotein B mRNA levels, and titers of infectious virus were similar in both IL-10 KO and wild-type animals. Separation of cells isolated from murine brain tissue into distinct populations using FACS, along with subsequent quantitative RT real-time PCR, showed that brain-infiltrating CD45(hi)/CD11b(-) and CD45(hi)/CD11b(int) were the cellular source of IL-10 in the brain. Taken together, these data demonstrate that MCMV brain infection of IL-10-deficient mice causes lethal disease, which occurs in the presence of a dysregulated IFN-gamma-mediated neuroimmune response.
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Affiliation(s)
| | | | | | | | | | - James R. Lokensgard
- *Corresponding author: James R. Lokensgard, 3-220 LRB/MTRF, 2001 6 Street S.E., Minneapolis, MN 55455, Phone: (612)-626-9914, Fax: (612)-626-9924, E-mail:
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Fehniger TA, Cai SF, Cao X, Bredemeyer AJ, Presti RM, French AR, Ley TJ. Acquisition of murine NK cell cytotoxicity requires the translation of a pre-existing pool of granzyme B and perforin mRNAs. Immunity 2007; 26:798-811. [PMID: 17540585 DOI: 10.1016/j.immuni.2007.04.010] [Citation(s) in RCA: 333] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Revised: 03/28/2007] [Accepted: 04/04/2007] [Indexed: 10/23/2022]
Abstract
Although activated murine NK cells can use the granule exocytosis pathway to kill target cells immediately upon recognition, resting murine NK cells are minimally cytotoxic for unknown reasons. Here, we showed that resting NK cells contained abundant granzyme A, but little granzyme B or perforin; in contrast, the mRNAs for all three genes were abundant. Cytokine-induced in vitro activation of NK cells resulted in potent cytotoxicity associated with a dramatic increase in granzyme B and perforin, but only minimal changes in mRNA abundance for these genes. The same pattern of regulation was found in vivo with murine cytomegalovirus infection as a physiologic model of NK cell activation. These data suggest that resting murine NK cells are minimally cytotoxic because of a block in perforin and granzyme B mRNA translation that is released by NK cell activation.
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Affiliation(s)
- Todd A Fehniger
- Division of Oncology, Department of Internal Medicine, Siteman Cancer Center, Washington University School of Medicine, St. Louis, MO 63110, USA
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Cheeran MCJ, Hu S, Sheng WS, Rashid A, Peterson PK, Lokensgard JR. Differential responses of human brain cells to West Nile virus infection. J Neurovirol 2005; 11:512-24. [PMID: 16338745 DOI: 10.1080/13550280500384982] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In recent years, West Nile virus (WNV) has emerged as a major cause of encephalitis in the United States. However, the neuropathogenesis of this flavivirus is poorly understood. In the present study, the authors used primary human brain cell cultures to investigate two neuropathogenic features: viral replication and induction of cytokines. Although neurons and astrocytes were found to support productive WNV infection, viral growth was poorly permissive in microglial cells. Compared to neuronal cultures that sustained viral growth for at least 2 weeks, replication peaked in astrocytes by 72 h post infection. In response to viral infection, astrocytes produced chemokines (CXCL10 and CCL5), but none of the cytokines (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, IL-6, interferon alpha or gamma) tested could be detected. Although microglial cells failed to support viral replication, WNV induced production of the proinflammatory cytokines IL-6 and TNF-alpha. Microglial cells also released robust amounts of the chemokines CXCL10 and CCL2, as well as lower levels of CCL5, in response to WNV infection. WNV-induced chemokine and cytokine production by microglia was coupled with activation of mitogen-activated protein kinase (MAPK) intracellular signaling pathways. Inhibition of p38 MAPK decreased chemokine production in response to WNV. Taken together, these findings suggest that microglial cell responses may influence the neuropathogenesis of WNV infection.
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Affiliation(s)
- Maxim C-J Cheeran
- Neuroimmunology Laboratory, Minneapolis Medical Research Foundation, University of Minnesota Medical School, 55455, USA.
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