Self-tolerance in a minimal model of the idiotypic network

Mechanism underlying polyvalent IgG-induced regulatory T cell activation and its clinical application: Anti-idiotypic regulatory T cell theory for immune tolerance

The regulatory T (Treg) cells constitute a functionally defined subpopulation of T cells that modulate the immune system and maintain immune tolerance through suppression of the development of autoimmune responses to self-antigens and allergic reactions to external antigens. Reduction in the number or function of Treg cells has been suggested as a key immune abnormality underlying the development of autoimmune and allergic diseases. In vitro studies have demonstrated that purified polyvalent immunoglobulin G (IgG) from multiple healthy blood donors can exert immunomodulatory effects on Treg cells. Incubation of polyvalent human IgG with purified CD4+CD25high T cells increased the intracellular expression of interleukin (IL)-10. Intravenous administration of polyvalent human IgG induced significant expansions of CD4+ Foxp3+ Treg cells and clinical improvements in patients with autoimmune diseases. In human clinical trials, intramuscular administration of autologous total IgG significantly increased the percentage of IL-10-producing CD4+ Treg cells in the peripheral blood of healthy subjects and provided significant clinical improvements in patients with atopic dermatitis. These results suggest a clinical usefulness of polyvalent IgG-induced activation of Treg cells in human subjects. This review proposes a new hypothesis for immune tolerance mechanism by integrating the pre-existing "idiotypic network theory" and "Treg cell theory" into an "anti-idiotypic Treg cell theory." Based on this hypothesis, an "active anti-idiotypic therapy" for allergic and autoimmune diseases using autologous polyvalent IgG (as immunizing antigens) is suggested as follows: (1) Intramuscular or subcutaneous administration of autologous polyvalent IgG produces numerous immunogenic peptides derived from idiotypes of autologous IgG through processing of dendritic cells, and these peptides activate anti-idiotypic Treg cells in the same subject. (2) Activated anti-idiotypic Treg cells secrete IL-10 and suppress Th2 cell response to allergens and autoimmune T cell response to self-antigens. (3) These events can induce a long-term clinical improvements in patients with allergic and autoimmune diseases. Further studies are needed to evaluate the detailed molecular mechanism underlying polyvalent IgG-induced Treg cell activation and the clinical usefulness of this immunomodulatory therapy for autoimmune and allergic diseases.

Regulatory T Cell-Targeted Immunomodulatory Therapy for Long-Term Clinical Improvement of Atopic Dermatitis: Hypotheses and Perspectives

Atopic dermatitis (AD) is a chronically relapsing inflammatory skin disorder characterized by itching and eczematous lesions. It is often associated with a personal or familial history of allergic diseases. Allergic inflammation induced by immunoglobulin E and T-helper type 2 (Th2) cell responses to common environmental agents has been suggested to play an essential role in AD pathogenesis. The standard therapies for AD, including topical or systemic agents, focus on controlling skin inflammation. Recently developed monoclonal antibody to interleukin-4 receptor alpha or Janus kinase inhibitors can provide significant clinical improvements in patients with AD by inhibiting Th2 cell-mediated skin inflammation. However, the clinical efficacy of the Th2 cell-targeted therapy is transient and incomplete in patients with AD. Patients with AD are seeking a permanent cure. Therefore, the development of novel immunomodulatory strategies that can improve a long-term clinical outcome and provide a long-term treatment-free clinical remission of AD (disease-modifying therapy) is needed. Regulatory T (Treg) cells play a critical role in the maintenance of immune tolerance and suppress the development of autoimmune and allergic diseases. This review provides three working hypotheses and perspectives for the treatment of AD by Treg cell activation. (1) A decreased number or function of Treg cells is a critical event that causes the activation of Th2 cells, leading to the development and maintenance of AD. (2) Activation of Treg cells is an effective therapeutic approach for AD. (3) Many different immunomodulatory strategies activating Treg cells can provide a long-term clinical improvement of AD by induction of immune tolerance. The Treg cell-targeted immunomodulatory therapies for AD include allergen immunotherapy, microbiota, vitamin D, polyvalent human immunoglobulin G, monoclonal antibodies to the surface antigens of T cell or antigen-presenting cell, and adoptive transfer of autologous Treg cells or genetically engineered Treg cells expanded in vitro.

Intramuscular administration of autologous total immunoglobulin G induces immunomodulatory effects on T cells in healthy human subjects: An open-labeled prospective single-arm trial

BACKGROUND

We hypothesized that intramuscular administration of autologous total immunoglobulin G (IgG) could induce an immunomodulatory effect in human subjects. In our previous studies, we showed that intramuscular administration of autologous total IgG could induce significant clinical improvements and increases of the serum levels of interleukin-10 (IL-10) and interferon-gamma (IFN-γ) in patients with atopic dermatitis.

OBJECTIVE

To investigate the mechanism of immunomodulation induced by intramuscular administration of autologous total IgG, we evaluated changes in T cells before and after intramuscular administrations of autologous total IgG in this study.

METHODS

Thirteen healthy adults received 8 intramuscular injections of 50 mg autologous total IgG for 4 weeks (from week 0 to week 4). The percentages of IL-10- or IFN-γ-producing peripheral blood T cells, as well as serum levels of IL-10, IFN-γ, and immunoglobulins, were measured at baseline (week 0) and at weeks 4, 8, and 12.

RESULTS

The percentage of IL-10-producing CD4+ T cells was significantly increased at weeks 8 and 12 compared to baseline (P < .05), while the percentage of IFN-γ-producing CD3+ T cells was significantly increased at week 12 compared to baseline (P < .05). There were no significant differences in the serum levels of IL-10, IFN-γ, and immunoglobulins before and after intramuscular administration of autologous total IgG (P > .05). No serious adverse events were observed.

CONCLUSION

Intramuscular administration of autologous total IgG induced immunomodulatory effects on T cells in healthy human subjects. This simple intervention could be a safe, effective, and economical T cell immunomodulation method for human subjects (NCT03695757).

Successfully treated recalcitrant atopic eczema with acupoint autohemotherapy: A case report and hypothesized mechanism of the therapy

Acupoint autohemotherapy at bilateral Zusanli (ST36) and Xuehai (SP10) was used to treat a 26-year-old female patient who had suffered from recalcitrant atopic eczema (AE) for five years. The treatment was applied at a frequency of once per week for the first month, followed by a three-month period of once every other week. At the end of treatment, the patient's AE symptoms were entirely resolved, and by the end of a six-month follow-up her immunoglobulin E level had returned to the normal range. Further, there was no relapse of AE symptoms during the six-month follow-up. Therefore, we hypothesized that after the repeated treatments the local inflammatory reaction induced by autologous blood injection triggered a local immune response, followed by a systemic immune response after the repeated treatment, finally leading to the anti-inflammation and immunomodulation effects. This case suggests that acupoint autohemotherapy could be used as an effective complementary treatment for recalcitrant AE, especially in cases where other treatments have failed. Further comparative studies are needed to corroborate the value and mechanisms of this therapy.

Network Organization of Antibody Interactions in Sequence and Structure Space: the RADARS Model

Adaptive immunity in vertebrates is a complex self-organizing network of molecular interactions. While deep sequencing of the immune-receptor repertoire may reveal clonal relationships, functional interpretation of such data is hampered by the inherent limitations of converting sequence to structure to function. In this paper, a novel model of antibody interaction space and network, termed radial adjustment of system resolution, RAdial ADjustment of System Resolution (RADARS), is proposed. The model is based on the radial growth of interaction affinity of antibodies towards an infinity of directions in structure space, each direction corresponding to particular shapes of antigen epitopes. Levels of interaction affinity appear as free energy shells of the system, where hierarchical B-cell development and differentiation takes place. Equilibrium in this immunological thermodynamic system can be described by a power law distribution of antibody-free energies with an ideal network degree exponent of phi square, representing a scale-free fractal network of antibody interactions. Plasma cells are network hubs, memory B cells are nodes with intermediate degrees, and B1 cells function as nodes with minimal degree. Overall, the RADARS model implies that a finite number of antibody structures can interact with an infinite number of antigens by immunologically controlled adjustment of interaction energy distribution. Understanding quantitative network properties of the system should help the organization of sequence-derived predicted structural data.

Antibody therapeutics and immunoregulation in cancer and autoimmune disease

Cancer and autoimmune disease are closely related, and many therapeutic antibodies are widely used in clinics for the treatment of both diseases. Among them, the anti-CD20 antibody has proven to be effective against both lymphoid malignancy and autoimmune disease. Moreover, immune checkpoint blockade using the anti-PD1/PD-L1/CTLA4 antibody has improved the prognosis of patients with refractory solid tumors. At the same time, however, over-enhancement of immunoreaction can induce autoimmune reaction. Although anti-TNF antibody therapies represent a breakthrough in the treatment of autoimmune diseases, optimal management is required to control the serious associated issues, including development and progression of cancer, and it is becoming more and more important to control the immunoreaction. In addition, next-generation antibody therapeutics such as antibody-drug conjugates and bispecific antibodies, are anticipated to treat uncontrolled cancer and autoimmune disease. IL-7R signaling plays an important role in the development and progression of both lymphoid malignancy and autoimmune disease. In addition, abnormal homing activity and steroid resistance caused by IL-7R signaling may worsen prognosis. Therefore, anti-IL-7R targeting antibody therapies that enable suppression of such pathophysiological status have the potential to be beneficial for the treatment of both diseases. In this review, we discuss current antibody therapeutics in cancer and autoimmune disease, and describe a new therapeutic strategy for immunoregulation including IL-7R targeting antibodies.

Can the Immune System Perform a t-Test?

The self-nonself discrimination hypothesis remains a landmark concept in immunology. It proposes that tolerance breaks down in the presence of nonself antigens. In strike contrast, in statistics, occurrence of nonself elements in a sample (i.e., outliers) is not obligatory to violate the null hypothesis. Very often, what is crucial is the combination of (self) elements in a sample. The two views on how to detect a change seem challengingly different and it could seem difficult to conceive how immunological cellular interactions could trigger responses with a precision comparable to some statistical tests. Here it is shown that frustrated cellular interactions reconcile the two views within a plausible immunological setting. It is proposed that the adaptive immune system can be promptly activated either when nonself ligands are detected or self-ligands occur in abnormal combinations. In particular we show that cellular populations behaving in this way could perform location statistical tests, with performances comparable to t or KS tests, or even more general data mining tests such as support vector machines or random forests. In more general terms, this work claims that plausible immunological models should provide accurate detection mechanisms for host protection and, furthermore, that investigation on mechanisms leading to improved detection in “in silico” models can help unveil how the real immune system works.

Autoantigen complementarity and its contributions to hallmarks of autoimmune disease

The question considered is, "What causes the autoimmune response to begin and what causes it to worsen into autoimmune disease?" The theory of autoantigen complementarity posits that the initiating immunogen causing disease is a protein complementary (antisense) to the self-antigen, rather than a response to the native protein. The resulting primary antibody elicits an anti-antibody response or anti-idiotype, consequently producing a disease-inciting autoantibody. Yet, not everyone who developes self-reactive autoantibodies will manifest autoimmune disease. What is apparent is that manifestation of disease is governed by the acquisition of multiple immune-compromising traits that increase susceptibility and drive disease. Taking into account current cellular, molecular, and genetic information, six traits, or 'hallmarks', of autoimmune disease were proposed: (1) Autoreactive cells evade deletion, (2) Presence of asymptomatic autoantibodies, (3) Hyperactivity of Fc-FcR pathway, (4) Susceptibility to environmental impact, (5) Antigenic modifications of self-proteins, (6) Microbial Infections. Presented here is a discussion on how components delineated in the theory of autoantigen complementarity potentially promote the acquisition of multiple 'hallmarks' of disease.

Autoantibodies 2015: From diagnostic biomarkers toward prediction, prognosis and prevention

At the 12th International Workshop on Autoantibodies and Autoimmunity (IWAA), organized in August 2014 in Sao Paulo, Brazil, more than 300 autoimmunologists gathered to discuss the status of many novel autoantibodies in clinical practice, and to envisage additional value of autoantibodies in terms of prediction, prognosis and prevention of autoimmune diseases. Two separate workshops were dedicated to standardization and harmonization of autoantibody testing and nomenclature: International Autoantibody Standardization (IAS) and International Consensus on ANA Patterns (ICAP). It was apparent to all in attendance that the discovery and elucidation of novel autoantibodies did not slow down, but that multiple challenges lay ahead of us in order to apply these discoveries to effective and efficient clinical practice. Importantly, this requires optimal bidirectional communication between clinicians and laboratory specialists, as well as close collaboration with the diagnostic industry. This paper is a report on the 12th IWAA in combination with a review of the recent developments in the field of autoantibodies.