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Sepúlveda N, Carneiro J, Lacerda E, Nacul L. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome as a Hyper-Regulated Immune System Driven by an Interplay Between Regulatory T Cells and Chronic Human Herpesvirus Infections. Front Immunol 2019; 10:2684. [PMID: 31824487 PMCID: PMC6883905 DOI: 10.3389/fimmu.2019.02684] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 10/31/2019] [Indexed: 12/13/2022] Open
Abstract
Autoimmunity and chronic viral infections are recurrent clinical observations in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), a complex disease with an unknown cause. Given these observations, the regulatory CD4+ T cells (Tregs) show promise to be good candidates for the underlying pathology due to their capacity to suppress the immune responses against both self and microbial antigens. Here, we discussed the overlooked role of these cells in the chronicity of Human Herpes Virus 6 (HHV6), Herpes Simplex 1 (HSV1), and Epstein–Barr virus (EBV), as often reported as triggers of ME/CFS. Using simulations of the cross-regulation model for the dynamics of Tregs, we illustrated that mild infections might lead to a chronically activated immune responses under control of Tregs if the responding clone has a high autoimmune potential. Such infections promote persistent inflammation and possibly fatigue. We then hypothesized that ME/CFS is a condition characterized by a predominance of this type of infections under control of Tregs. In contrast, healthy individuals are hypothesized to trigger immune responses of a virus-specific clone with a low autoimmune potential. According to this hypothesis, simple model simulations of the CD4+ T-cell repertoire could reproduce the increased density and percentages of Tregs observed in patients suffering from the disease, when compared to healthy controls. A deeper analysis of Tregs in the pathogenesis of ME/CFS will help to assess the validity of this hypothesis.
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Affiliation(s)
- Nuno Sepúlveda
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom.,Centre of Statistics and Its Applications, University of Lisbon, Lisbon, Portugal
| | - Jorge Carneiro
- Quantitative Organism Biology Group, Gulbenkian Institute of Science, Oeiras, Portugal
| | - Eliana Lacerda
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Luis Nacul
- Department of Clinical Research, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
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Escape of pathogens from the host immune response by mutations and mimicry. Possible means to improve vaccine performance. Med Hypotheses 2015; 85:664-9. [PMID: 26341417 DOI: 10.1016/j.mehy.2015.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 08/13/2015] [Indexed: 11/21/2022]
Abstract
The ability of certain pathogens, such as human immunodeficiency, hepatitis C, herpes simplex, influenza viruses, Plasmodium falciparum, etc., to escape from host immune response is generally ascribed to high mutation rate of their genome. We challenge this assumption and propose that molecular mimicry of host antigens by these pathogens could also participate to this resistance. Several studies show that there is no correlation between the mutation rate value of a pathogen and the possibility to develop an effective vaccine. On the other hand, pathogens which do not respond to vaccine are usually reported to display host protein mimicry. We propose to suppress in the thymus the epitopes of the self which are in common with the pathogen. This could be achieved by intrathymic injection of antibodies against this microorganism. These antibodies would be obtained by vaccination of a foreign animal species. It is expected that the negative selection of the CD4(+) and CD8(+) T lymphocytes specific for these epitopes would be prevented, that the number of epitopes recognized as foreign to the host would be increased and that the immune response diversity would be enhanced.
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Hulspas R, O'Gorman MR, Wood BL, Gratama JW, Sutherland DR. Considerations for the control of background fluorescence in clinical flow cytometry. CYTOMETRY PART B-CLINICAL CYTOMETRY 2009; 76:355-64. [DOI: 10.1002/cyto.b.20485] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Gebhardt BM, Halford WP. Evidence that spontaneous reactivation of herpes virus does not occur in mice. Virol J 2005; 2:67. [PMID: 16109179 PMCID: PMC1208961 DOI: 10.1186/1743-422x-2-67] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2005] [Accepted: 08/18/2005] [Indexed: 11/11/2022] Open
Abstract
Background Some species, including humans and rabbits, exhibit periodic viral reactivation and shed infectious virus at the infected end organ. Mice may be an exception, because spontaneous shedding of infectious virus rarely, if ever, occurs. However, spontaneous molecular reactivation, i.e., the expression of a few viral genes and the synthesis of the viral glycoproteins coded for by these genes, has been reported. This finding has prompted the assumption that molecular reactivation is an indicator of reactivation and the production of infectious virus. The goal of this study was to differentiate between viral gene expression during latency and the episodic production of infectious virus in mice. Results Viral reactivation and infection were not seen in herpes simplex virus type 1 (HSV-1) latent ganglion graft recipient BALB/c scid or immunocompetent BALB/c mice, which survived the 65-day observation period with no evidence of viral infection although the immunocompetent mice developed cellular and humoral immunity to HSV-1. In contrast, BALB/c scid recipients of ganglia containing reactivating virus invariably developed a local and, subsequently, systemic viral infection and died within 14 days. Immunocompetent BALB/c mice that received ganglion grafts containing reactivating virus survived the infection and became immune to the virus. Trigeminal ganglia removed from scid and immunocompetent recipient graft sites 5, 14, and 28 days after transplantation contained latent virus and viable neurons. Conclusion The results suggest that, within the limits of detection of the experiments, spontaneous episodic production of immunogenic viral antigens but not of infectious virus occurs in mouse neural ganglia during latency.
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Affiliation(s)
- Bryan M Gebhardt
- LSU Eye Center, Louisiana State University Health Sciences Center, New Orleans, LA 70112 USA
| | - William P Halford
- Department of Veterinary Microbiology, Montana State University, Bozeman, MT 59718 USA
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Abstract
Herpes stromal keratitis (HSK) is a significant inflammatory disease of the cornea as a result of herpes simplex virus (HSV) infection often progressing to vision loss if left untreated. However, even with immunosuppressive compounds and anti-viral drug treatment, HSV continues to be the leading cause of infectious corneal blindness in the industrialized world. The inflammatory nature of the disease is the root of the pathogenic process characterized by irreversible corneal scarring, neovascularization of the avascular cornea, and infiltration of activated leukocytes. Experimental evidence using mice suggest HSK is the result of either molecular mimicry or a bystander activation phenomenon. This review will revisit the basis of HSK focusing on issues that pertain to the autoimmune component versus collateral damage as a result of non-specific activation as a means to explain the pathologic manifestations of the disease.
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Affiliation(s)
- S Wickham
- Department of Ophthalmology, Microbiology, and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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Abstract
We give an update on clinical, immunological, and therapeutic advances in the field of myasthenia gravis, including a summary of suggested therapeutic recommendations.
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Affiliation(s)
- F Romi
- Department of Neurology, Haukeland University Hospital, Bergen, Norway.
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Robinson SR, Dobson C, Lyons J. Challenges and directions for the pathogen hypothesis of Alzheimer's disease. Neurobiol Aging 2004; 25:629-37. [PMID: 15172741 DOI: 10.1016/j.neurobiolaging.2003.12.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Revised: 11/21/2003] [Accepted: 12/02/2003] [Indexed: 10/26/2022]
Abstract
This paper critically reviews the possibility that infiltration of the brain by pathogens (e.g. Herpes simplex virus type 1 (HSV1) or Chlamydophila pneumoniae (Cp)) acts as a trigger or co-factor for Alzheimer's disease (AD). The evidence currently available is limited and in some cases inconsistent, but it does justify the need for more vigorous investigation of this hypothesis. An issue of particular concern is the paucity of experimental evidence showing that pathogens can elicit the neuropathological changes and cognitive deficits that characterise AD. Other weaknesses include a failure to obtain independent confirmation of Cp in AD brains, and a lack of evidence for HSV1 proteins or intact virions in AD brain tissue. Future avenues of investigation that might prove fruitful include epidemiological investigations of the incidence of AD in individuals who are either immunosuppressed or have received chronic antiviral or antibiotic therapy. There is also a need to consider systemic infections as potential contributors to the pathogenesis of AD.
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Affiliation(s)
- Stephen R Robinson
- Department of Psychology, School of Psychology, Psychiatry and Psychological Medicine, Monash University, Clayton, Vic. 3800, Australia.
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Infante AJ, Baillargeon J, Kraig E, Lott L, Jackson C, Hämmerling GJ, Raju R, David C. Evidence of a diverse T cell receptor repertoire for acetylcholine receptor, the autoantigen of myasthenia gravis. J Autoimmun 2003; 21:167-74. [PMID: 12935786 DOI: 10.1016/s0896-8411(03)00086-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We utilized two methods to look for T cell clonal expansions in myasthenia gravis (MG). We analyzed TCRBV CDR3 length polymorphism (spectratyping) to look for evidence of clonal expansion of CD4 or CD8 T cells directly from peripheral blood of MG patients. No statistically significant differences were found between the diversity of TCR repertoires in MG patients compared to normal control individuals when analyzed as groups. Rare oligoclonal expansions were detected in some individual MG patients but the significance of these findings is unclear. Next, we analyzed a panel of T cell hybridomas from acetylcholine receptor (AChR) immunized, MG-susceptible HLA-DR3 transgenic mice. The epitope specificity, TCRBV gene usage and CDR3 sequences of these hybridomas were highly diverse. We conclude there is only limited evidence for restricted TCR repertoire usage in human MG and suggest this may be due to the inability of HLA-DR molecules to select for restricted TCR recognition of AChR epitopes.
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MESH Headings
- Adult
- Aged
- Animals
- Autoantigens/immunology
- DNA, Complementary/genetics
- Disease Models, Animal
- Epitopes/immunology
- Female
- HLA-DR3 Antigen/genetics
- HLA-DR3 Antigen/immunology
- Humans
- Hybridomas/immunology
- Male
- Mice
- Middle Aged
- Myasthenia Gravis/blood
- Myasthenia Gravis/genetics
- Myasthenia Gravis/immunology
- Polymorphism, Genetic/immunology
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Cholinergic/immunology
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Affiliation(s)
- Anthony J Infante
- Department of Pediatrics, University of Texas Health Science Center, 7703 Floyd Curl Drive MC 7790, San Antonio, TX 78229-3900, USA.
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Stacy S, Gelb BE, Koop BA, Windle JJ, Wall KA, Krolick KA, Infante AJ, Kraig E. Split tolerance in a novel transgenic model of autoimmune myasthenia gravis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:6570-9. [PMID: 12444169 DOI: 10.4049/jimmunol.169.11.6570] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Because it is one of the few autoimmune disorders in which the target autoantigen has been definitively identified, myasthenia gravis (MG) provides a unique opportunity for testing basic concepts of immune tolerance. In most MG patients, Abs against the acetylcholine receptors (AChR) at the neuromuscular junction can be readily identified and have been directly shown to cause muscle weakness. T cells have also been implicated and appear to play a role in regulating the pathogenic B cells. A murine MG model, generated by immunizing mice with heterologous AChR from the electric fish Torpedo californica, has been used extensively. In these animals, Abs cross-react with murine AChR; however, the T cells do not. Thus, to study tolerance to AChR, a transgenic mouse model was generated in which the immunodominant Torpedo AChR (T-AChR) alpha subunit is expressed in appropriate tissues. Upon immunization, these mice showed greatly reduced T cell responses to T-AChR and the immunodominant alpha-chain peptide. Limiting dilution assays suggest the likely mechanism of tolerance is deletion or anergy. Despite this tolerance, immunization with intact T-AChR induced anti-AChR Abs, including Abs against the alpha subunit, and the incidence of MG-like symptoms was similar to that of wild-type animals. Furthermore, evidence suggests that this B cell response to the alpha-chain receives help from T cells directed against the other AChR polypeptides (beta, gamma, or delta). This model offers a novel opportunity to elucidate mechanisms of tolerance regulation to muscle AChR and to clarify the role of T cells in MG.
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Affiliation(s)
- Sue Stacy
- Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio 78229, USA
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Carr DJ, Härle P, Gebhardt BM. The immune response to ocular herpes simplex virus type 1 infection. Exp Biol Med (Maywood) 2001; 226:353-66. [PMID: 11393165 DOI: 10.1177/153537020122600501] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Herpes simplex virus type 1 (HSV-1) is a prevalent microbial pathogen infecting 60% to 90% of the adult world population. The co-evolution of the virus with humans is due, in part, to adaptations that the virus has evolved to aid it in escaping immune surveillance, including the establishment of a latent infection in its human host. A latent infection allows the virus to remain in the host without inducing tissue pathology or eliciting an immune response. During the acute infection or reactivation of latent virus, the immune response is significant, which can ultimately result in corneal blindness or fatal sporadic encephalitis. In fact, HSV-1 is one of the leading causes of infectious corneal blindness in the world as a result of chronic episodes of viral reactivation leading to stromal keratitis and scarring. Significant inroads have been made in identifying key immune mediators that control ocular HSV-1 infection and potentially viral reactivation. Likewise, viral mechanisms associated with immune evasion have also been identified and will be discussed. Lastly, novel therapeutic strategies that are currently under development show promise and will be included in this review. Most investigators have taken full advantage of the murine host as a viable working in vivo model of HSV-1 due to the sensitivity and susceptibility to viral infection, ease of manipulation, and a multitude of developed probes to study changes at the cellular and molecular levels. Therefore, comments in this review will primarily be restricted to those observations pertaining to the mouse model and the assumption (however great) that similar events occur in the human condition.
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Affiliation(s)
- D J Carr
- Department of Ophthalmology, The University of Oklahoma Health Sciences Center, Oklahoma City 73104, USA.
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