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Tassinari V, Cerboni C, Soriani A. Self or Non-Self? It Is also a Matter of RNA Recognition and Editing by ADAR1. BIOLOGY 2022; 11:biology11040568. [PMID: 35453767 PMCID: PMC9024829 DOI: 10.3390/biology11040568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/01/2022] [Accepted: 04/06/2022] [Indexed: 01/19/2023]
Abstract
Simple Summary A fundamental feature of innate immune cells is to detect the presence of non-self, such as potentially harmful nucleic acids, by germline-encoded specialized receptors called pattern recognition receptors (PRRs). ADAR1 is one key enzyme avoiding aberrant type I interferon (IFN-I) production and immune cell activation by the conversion of adenosine to inosine (A-to-I) in double-stranded RNA (dsRNA) structures that arise in self mRNA containing specific repetitive elements. This review intends to give an up-to-date and detailed overview of the ADAR1-mediated ability to modulate the immune response in autoimmune diseases and cancer progression. Abstract A-to-I editing is a post-transcriptional mechanism affecting coding and non-coding dsRNAs, catalyzed by the adenosine deaminases acting on the RNA (ADAR) family of enzymes. A-to-I modifications of endogenous dsRNA (mainly derived from Alu repetitive elements) prevent their recognition by cellular dsRNA sensors, thus avoiding the induction of antiviral signaling and uncontrolled IFN-I production. This process, mediated by ADAR1 activity, ensures the activation of an innate immune response against foreign (non-self) but not self nucleic acids. As a consequence, ADAR1 mutations or its de-regulated activity promote the development of autoimmune diseases and strongly impact cell growth, also leading to cancer. Moreover, the excessive inflammation promoted by Adar1 ablation also impacts T and B cell maturation, as well as the development of dendritic cell subsets, revealing a new role of ADAR1 in the homeostasis of the immune system.
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Approach to the Adult Acute Lymphoblastic Leukemia Patient. J Clin Med 2019; 8:jcm8081175. [PMID: 31390838 PMCID: PMC6722778 DOI: 10.3390/jcm8081175] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/29/2019] [Accepted: 08/01/2019] [Indexed: 02/06/2023] Open
Abstract
During recent decades, understanding of the molecular mechanisms of acute lymphoblastic leukemia (ALL) has improved considerably, resulting in better risk stratification of patients and increased survival rates. Age, white blood cell count (WBC), and specific genetic abnormalities are the most important factors that define risk groups for ALL. State-of-the-art diagnosis of ALL requires cytological and cytogenetical analyses, as well as flow cytometry and high-throughput sequencing assays. An important aspect in the diagnostic characterization of patients with ALL is the identification of the Philadelphia (Ph) chromosome, which warrants the addition of tyrosine kinase inhibitors (TKI) to the chemotherapy backbone. Data that support the benefit of hematopoietic stem cell transplantation (HSCT) in high risk patient subsets or in late relapse patients are still questioned and have yet to be determined conclusive. This article presents the newly published data in ALL workup and treatment, putting it into perspective for the attending physician in hematology and oncology.
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Cohn M. Thoughts engendered by Bretscher's Two-step, Two-signal model for a peripheral self-non-self discrimination and the origin of primer effector T helpers. Scand J Immunol 2015; 81:87-95. [PMID: 25413363 DOI: 10.1111/sji.12255] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 10/27/2014] [Indexed: 01/18/2023]
Abstract
There are three questions under re-examination here that have been inspired by Bretscher's 'Two-step, Two-signal' model. First, what is the nature of the steps required in order for antigen-responsive cells to become effectors? Second, how does the immune system get started? Third and the most troublesome, what is the mechanism that relates the delivery of the two signals? To answer the first question, Bretscher proposes a pathway that I will place in another context by comparing it with what had been envisaged under the Associative Recognition of Antigen (ARA) model. The second question, how does the immune system gets started, is crucial to our understanding of the self-non-self discrimination. This problem boils down to, what is the origin of the first effector T helper (eTh) cells required to activate all antigen-responsive cells including the T helpers themselves (the primer problem)? To deal with this question, I proposed an antigen-independent pathway to primer eTh. Bretscher presents us with an antigen-dependent pathway to primer eTh. As competing models are precious in clarifying thinking and in guiding experimentation, I felt it important to reanalyse the two models and look for ways to decide between them. The third question deals with the requirement for and the mechanism of associative (linked) recognition of antigen (ARA). The concept of ARA is so compelling at both the experimental and theoretical levels that to save it, a new perspective will be introduced.
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Affiliation(s)
- M Cohn
- Conceptual Immunology Group, The Salk Institute, La Jolla, CA, USA
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Accolla RS, Lombardo L, Abdallah R, Raval G, Forlani G, Tosi G. Boosting the MHC Class II-Restricted Tumor Antigen Presentation to CD4+ T Helper Cells: A Critical Issue for Triggering Protective Immunity and Re-Orienting the Tumor Microenvironment Toward an Anti-Tumor State. Front Oncol 2014; 4:32. [PMID: 24600588 PMCID: PMC3927100 DOI: 10.3389/fonc.2014.00032] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 02/04/2014] [Indexed: 01/06/2023] Open
Abstract
Although the existence of an immune response against tumor cells is well documented, the fact that tumors take off in cancer patients indicates that neoplastic cells can circumvent this response. Over the years many investigators have described strategies to rescue the anti-tumor immune response with the aim of creating specific and long-lasting protection against the disease. When exported to human clinical settings, these strategies have revealed in most cases a very limited, if any, positive outcome. We believe that the failure is mostly due to the inadequate triggering of the CD4+ T helper (TH) cell arm of the adaptive immunity, as TH cells are necessary to trigger all the immune effector mechanisms required to eliminate tumor cells. In this review, we focus on novel strategies that by stimulating MHC class II-restricted activation of TH cells generate a specific and persistent adaptive immunity against the tumor. This point is of critical importance for both preventive and therapeutic anti-tumor vaccination protocols, because adaptive immunity with its capacity to produce specific, long-lasting protection and memory responses is indeed the final goal of vaccination. We will discuss data from our as well as other laboratories which strongly suggest that triggering a specific and persistent anti-tumor CD4+ TH cell response stably modify not only the tumor microenvironment but also tumor-dependent extratumor microenvironments by eliminating and/or reducing the blood-derived tumor infiltrating cells that may have a pro-tumor growth function such as regulatory CD4+/CD25+ T cells and myeloid-derived-suppressor cells. Within this frame, therefore, we believe that the establishment of a pro-tumor environment is not the cause but simply the consequence of the tumor strategy to primarily counteract components of the adaptive cellular immunity, particularly TH lymphocytes.
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Affiliation(s)
- Roberto S Accolla
- Department of Surgical and Morphological Sciences, University of Insubria , Varese , Italy
| | - Letizia Lombardo
- Department of Surgical and Morphological Sciences, University of Insubria , Varese , Italy
| | - Rawan Abdallah
- Department of Surgical and Morphological Sciences, University of Insubria , Varese , Italy
| | - Goutham Raval
- Department of Surgical and Morphological Sciences, University of Insubria , Varese , Italy
| | - Greta Forlani
- Department of Surgical and Morphological Sciences, University of Insubria , Varese , Italy
| | - Giovanna Tosi
- Department of Surgical and Morphological Sciences, University of Insubria , Varese , Italy
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What is so special about thinking; after all, we all do it! Exp Mol Pathol 2012; 93:354-64. [DOI: 10.1016/j.yexmp.2012.08.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 08/17/2012] [Indexed: 12/24/2022]
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Cohn M. The evolutionary context for a self-nonself discrimination. Cell Mol Life Sci 2010; 67:2851-62. [PMID: 20585970 PMCID: PMC2956437 DOI: 10.1007/s00018-010-0438-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 06/10/2010] [Indexed: 10/19/2022]
Abstract
This essay was written to illustrate how one might think about the immune system. The formulation of valid theories is the basic component of how-to-think because the reduction of large and complex data sets by the use of logic into a succinct model with predictability and explanatory power, is the only way that we have to arrive at "understanding". Whether it is to achieve effective manipulation of the system or for pure pleasure, "understanding" is a universally agreed upon goal. It is in the nature of science that theories are there to be disproven. An experimentally disproven theory is a successful one. As they fail experimental test one by one, we end up with a default theory, that is, one that has yet to fail. Here, using the self-nonself discrimination as an example, how-to-think as I see it, will be illustrated.
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Affiliation(s)
- Melvin Cohn
- Conceptual Immunology Group, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA.
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Cohn M. On the critique by Colin Anderson of 'A reply to Dembic: on an end to the beginning of mis-understanding the immune response'. Scand J Immunol 2009; 70:1-9. [PMID: 19522761 PMCID: PMC2729654 DOI: 10.1111/j.1365-3083.2009.02264.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
My proposal of a set of postulates that can be used to guide computer modeling has understandably met with significant criticism at two levels, semantic and conceptual. The major source of contention is my assumption that the sorting of the paratopic repertoire is both necessary and sufficient to explain the evolutionarily selected mechanism for the self-nonself discrimination. While 'necessary' is agreed upon, 'sufficient' is debatable as this commentary illustrates. My essay is in defense of 'sufficiency'.
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Affiliation(s)
- M Cohn
- Conceptual Immunology Group, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Costantino CM, Baecher-Allan CM, Hafler DA. Human regulatory T cells and autoimmunity. Eur J Immunol 2008; 38:921-4. [PMID: 18395861 DOI: 10.1002/eji.200738104] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
CD4+CD25+ regulatory T cells (Treg) appear to be critical in regulating immune responses to self-antigens. Treg deficiency is associated with several human autoimmune diseases. Although substantial progress has been made in the study of murine and human Treg, their fundamental mechanism of action remains unknown. In this review, we discuss the phenotype of human natural Treg, their functional mechanism, and their role in autoimmune disease.
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Affiliation(s)
- Cristina M Costantino
- Division of Molecular Immunology, Center for Neurologic Diseases, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
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Aries PM, Lamprecht P, Gross WL. Biological therapies: new treatment options for ANCA-associated vasculitis? Expert Opin Biol Ther 2007; 7:521-33. [PMID: 17373903 DOI: 10.1517/14712598.7.4.521] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Biological therapies enable us to apply highly selective targeting components to modulate the immune response. Until now, a few controlled studies investigated the efficacy of TNF-alpha blocking agents in systemic vasculitis have been carried out, but, in general, they were falling short of expectations. However, there is conducive evidence that TNF-alpha blockers are advantageous in antineutrophil cytoplasmic antibodies (ANCA)-associated vasculitis, at least in selected disease stages. Likewise, although the efficacy of the monoclonal CD20 antibody rituximab in ANCA-associated vasculitis is obvious, the effect on predominantly granulomatous disease activity in Wegener's granulomatosis is less clear. In addition, interferon-alpha is used for induction treatment particularly in Churg-Strauss syndrome. Even though the effectiveness and safety of short-term administration was confirmed by case series, severe side effects after long-term treatment relativized the initial results. This review presents the recent data on the use of biologicals in vasculitis and appraises the knowledge in the clinical context.
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MESH Headings
- Antibodies, Antineutrophil Cytoplasmic/adverse effects
- Antibodies, Antineutrophil Cytoplasmic/immunology
- Antibodies, Antineutrophil Cytoplasmic/physiology
- Antibodies, Monoclonal/adverse effects
- Antibodies, Monoclonal/blood
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Monoclonal, Murine-Derived
- Antirheumatic Agents/adverse effects
- Antirheumatic Agents/therapeutic use
- Biological Therapy/methods
- Churg-Strauss Syndrome/drug therapy
- Etanercept
- Granulomatosis with Polyangiitis/drug therapy
- Granulomatosis with Polyangiitis/etiology
- Granulomatosis with Polyangiitis/physiopathology
- Humans
- Immunoglobulin G/adverse effects
- Immunoglobulin G/blood
- Immunoglobulin G/therapeutic use
- Immunologic Factors/therapeutic use
- Infliximab
- Interferon-alpha/therapeutic use
- Randomized Controlled Trials as Topic
- Receptors, Tumor Necrosis Factor/blood
- Receptors, Tumor Necrosis Factor/therapeutic use
- Rituximab
- Tumor Necrosis Factor-alpha/antagonists & inhibitors
- Tumor Necrosis Factor-alpha/blood
- Tumor Necrosis Factor-alpha/immunology
- Vasculitis/drug therapy
- Vasculitis/etiology
- Vasculitis/immunology
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Affiliation(s)
- Peer M Aries
- University Hospital Schleswig-Holstein, Campus Luebeck, Department of Rheumatology and Rheumaklinik Bad Bramstedt, Ratzeburger Allee 160, 23538 Lübeck, Germany.
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Abstract
In analysing the Zinkernagel and Hengartner's 'Credo 2004,' Anderson introduces his 'development-context model' for the immunity-tolerance discrimination. He compares this model with the 'geographical model of Credo 2004' and our 'time-based two-signal model'. The discussion here deals with the advantages and limitations of the Anderson model considered largely at the level of principle. A meaningful discussion requires that we agree on the principle which separates the pathway of the effector output into two decision steps, the sorting of the repertoire and the regulation of effector class. The mechanism for the sorting of the repertoire is what might be referred to as the Self-Nonself discrimination. The black box approach, antigen-in, effector response-out, is what is referred to as the immunity-tolerance discrimination which includes the sorting of the repertoire. If this point of principle is accepted then we are left with a 'time-based two signal default model'.
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Affiliation(s)
- M Cohn
- Conceptual Immunology Group, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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Monk NJ, Hargreaves REG, Simpson E, Dyson JP, Jurcevic S. Transplant tolerance: models, concepts and facts. J Mol Med (Berl) 2006; 84:295-304. [PMID: 16501935 DOI: 10.1007/s00109-005-0006-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Accepted: 09/27/2005] [Indexed: 12/18/2022]
Abstract
Despite extensive research, our understanding of immunological tolerance to self-antigens is incomplete, and the goal of achieving tolerance to allogeneic transplanted tissue remains elusive. Currently, it is generally believed that the blockade of T cell co-stimulation offers considerable potential for achieving tolerance in the clinical setting. However, the recent finding that CD154-specific antibody may act through the depletion of activated T cells rather than co-stimulation blockade alone highlights the need for a re-evaluation of published data and the role of co-stimulation blockade in transplant tolerance. Activated T cells are programmed to die unless they receive sufficient survival signals in the form of inflammatory and lymphotropic cytokines produced by activated antigen-presenting cells or the T cells themselves. In conditions where the threshold for surviving activation is not reached, for example when a small number of responder T cells are activated in the absence of substantial injury or inflammation, the ensuing death of all activated T cells can result in deletional tolerance. Therefore, we propose that tolerance represents a failure of T cells to survive activation and develop into memory cells. This concept is likely to apply in the transplant setting, where the strength of the alloresponse depends on both the number/phenotype of the recipients' alloreactive T cells and immunogenicity of the transplanted tissue. Hence, in some rodent donor-recipient strain combinations that instigate a weak alloresponse, many treatments that only modestly decrease the alloresponse can achieve tolerance. In contrast, clinical transplantation is characterised by a strong alloresponse and highly immunogenic allografts, and thus, most treatments fail to control allograft rejection, and tolerance is difficult to achieve.
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Affiliation(s)
- Nicola J Monk
- Department of Nephrology & Transplantation, King's College, Guy's, King's and St Thomas' Medical School, 5th Floor TGH, Guy's Hospital, London, UK
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Wiertsema SP, Veenhoven RH, Sanders EAM, Rijkers GT. Immunologic screening of children with recurrent otitis media. Curr Allergy Asthma Rep 2005; 5:302-7. [PMID: 15967072 DOI: 10.1007/s11882-005-0070-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Some 5% to 10% of all infants and toddlers suffer from four or more episodes of otitis per year. Usually, this is a temporary problem that resolves with increasing age. In a minority of cases, otitis episodes are frequent or have an abnormal course, with complications such as mastoiditis. In these cases, immunologic screening is indicated, to exclude an immunodeficiency. Agammaglobulinemia or hypogammaglobulinemia is rare among these patients. Other immune defects that occur more often are deficient or lowered immunoglobulin (Ig)A or decreased levels of one or more IgG subclass, in particular IgG2. The specific antibody response to bacterial capsular polysaccharides often is disturbed. These findings can give direction to the treatment of children with frequent, recurrent otitis.
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Affiliation(s)
- Selma P Wiertsema
- Department of Immunology, University Medical Center Utrecht, Wilhelmina Children's Hospital, KC03.063.0, Lundlaan 6, 3584 EA Utrecht, The Netherlands
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