What do we mean by oral tolerance?

Oral Tolerance Induction by Bothrops jararaca Venom in a Murine Model and Cross-Reactivity with Toxins of Other Snake Venoms

Oral tolerance is defined as a specific suppression of cellular and humoral immune responses to a particular antigen through prior oral administration of an antigen. It has unique immunological importance since it is a natural and continuous event driven by external antigens. It is characterized by low levels of IgG in the serum of animals after immunization with the antigen. There is no report of induction of oral tolerance to Bothrops jararaca venom. Here, we induced oral tolerance to B. jararaca venom in BALB/c mice and evaluated the specific tolerance and cross-reactivity with the toxins of other Bothrops species after immunization with the snake venoms adsorbed to/encapsulated in nanostructured SBA-15 silica. Animals that received a high dose of B. jararaca venom (1.8 mg) orally responded by showing antibody titers similar to those of immunized animals. On the other hand, mice tolerized orally with three doses of 1 µg of B. jararaca venom showed low antibody titers. In animals that received a low dose of B. jararaca venom and were immunized with B. atrox or B. jararacussu venom, tolerance was null or only partial. Immunoblot analysis against the venom of different Bothrops species provided details about the main tolerogenic epitopes and clearly showed a difference compared to antiserum of immunized animals.

A Practical, Stepwise Approach to Peanut Oral Immunotherapy in Clinical Practice: Benefits and Risks

Food allergies are common, affecting 6-8% of the children in the United States. There is a significant burden on the quality of life of allergic children and their caregivers, due to multiple dietary, social and psychological restrictions. Peanut allergy affects approximately 2-5% of the school-age children. Despite the recommended dietary avoidance, reactions tend to occur due to unintentional exposures and the fear of accidental ingestions potentially resulting in anaphylaxis and death, which creates a lot of anxiety in peanut-allergic individuals. Peanut oral immunotherapy (POIT) has emerged as a form of active treatment and has shown high efficacy in research trials with the majority of participants achieving desensitization and protection from trace exposures. An improved quality of life has also been noted following successful POIT. The risks of POIT should be balanced against the benefits resulting from successful treatment for each individual. Rates of allergic reactions and anaphylaxis are reported to be higher in individuals pursuing therapy, but most subjects will experience mild or moderate reactions during treatment. The landscape of peanut allergy management is changing and the future offers more options for patients than were previously available. Shared decision-making, which is the process of how to choose between different available options, becomes an ongoing discussion between the clinician and the patient, which will ensure achievement of the best possible outcome for the peanut-allergic child. This is a multistep process that evaluates the benefits and risks of therapy or no therapy, as well as patient and family preferences and we review it in detail in this manuscript with the aim to provide clinicians with a practical approach.

Weighing the benefits and risks of oral immunotherapy in clinical practice

Food allergies are common and affect 6-8% of children in the United States; they pose a significant burden on the quality of life of children with allergy and their caregivers due to multiple daily restrictions. Despite the recommended dietary avoidance, reactions tend to occur due to unintentional exposure to the allergenic food trigger. Fear of accidental ingestions with potentially severe reactions, including anaphylaxis and death, creates anxiety in individuals with food allergy. Oral immunotherapy has emerged as a form of active and potentially disease-modifying treatment for common food allergies encountered in childhood. The efficacy of oral immunotherapy is high, with the majority of participants achieving desensitization and, as a result, protection from trace exposures and improved quality of life. The main risk of oral immunotherapy consists of allergic reactions to treatment. In general, rates of allergic reactions and anaphylaxis are reported to be higher in individuals pursuing therapy options, but most subjects who undergo oral immunotherapy will likely experience mild or moderate reactions during treatment. Adverse events tend to reduce in both frequency and number in the maintenance period. The use of immune modulators alongside oral immunotherapy has been suggested, with the aim to improve efficacy and safety, and to facilitate the overall process. It is evident that the landscape of food allergy management is changing and that the future looks brighter, with different options emerging over time. The process of how to choose the appropriate option becomes a discussion between the clinician and the patient, which involves a joint review of the current medical evidence but also the patient's preference for balancing particular attributes of the treatment. By working together, providers and patients will ensure achievement of the best possible outcome for children with food allergies.

Gliadin Nanoparticles Induce Immune Tolerance to Gliadin in Mouse Models of Celiac Disease

BACKGROUND & AIMS

Celiac disease could be treated, and potentially cured, by restoring T-cell tolerance to gliadin. We investigated the safety and efficacy of negatively charged 500-nm poly(lactide-co-glycolide) nanoparticles encapsulating gliadin protein (TIMP-GLIA) in 3 mouse models of celiac disease. Uptake of these nanoparticles by antigen-presenting cells was shown to induce immune tolerance in other animal models of autoimmune disease.

METHODS

We performed studies with C57BL/6; RAG1^-/- (C57BL/6); and HLA-DQ8, huCD4 transgenic Ab0 NOD mice. Mice were given 1 or 2 tail-vein injections of TIMP-GLIA or control nanoparticles. Some mice were given intradermal injections of gliadin in complete Freund's adjuvant (immunization) or of soluble gliadin or ovalbumin (ear challenge). RAG^-/- mice were given intraperitoneal injections of CD4⁺CD62L^-CD44^hi T cells from gliadin-immunized C57BL/6 mice and were fed with an AIN-76A-based diet containing wheat gluten (oral challenge) or without gluten. Spleen or lymph node cells were analyzed in proliferation and cytokine secretion assays or by flow cytometry, RNA sequencing, or real-time quantitative polymerase chain reaction. Serum samples were analyzed by gliadin antibody enzyme-linked immunosorbent assay, and intestinal tissues were analyzed by histology. Human peripheral blood mononuclear cells, or immature dendritic cells derived from human peripheral blood mononuclear cells, were cultured in medium containing TIMP-GLIA, anti-CD3 antibody, or lipopolysaccharide (controls) and analyzed in proliferation and cytokine secretion assays or by flow cytometry. Whole blood or plasma from healthy volunteers was incubated with TIMP-GLIA, and hemolysis, platelet activation and aggregation, and complement activation or coagulation were analyzed.

RESULTS

TIMP-GLIA did not increase markers of maturation on cultured human dendritic cells or induce activation of T cells from patients with active or treated celiac disease. In the delayed-type hypersensitivity (model 1), the HLA-DQ8 transgenic (model 2), and the gliadin memory T-cell enteropathy (model 3) models of celiac disease, intravenous injections of TIMP-GLIA significantly decreased gliadin-specific T-cell proliferation (in models 1 and 2), inflammatory cytokine secretion (in models 1, 2, and 3), circulating gliadin-specific IgG/IgG2c (in models 1 and 2), ear swelling (in model 1), gluten-dependent enteropathy (in model 3), and body weight loss (in model 3). In model 1, the effects were shown to be dose dependent. Splenocytes from HLA-DQ8 transgenic mice given TIMP-GLIA nanoparticles, but not control nanoparticles, had increased levels of FOXP3 and gene expression signatures associated with tolerance induction.

CONCLUSIONS

In mice with gliadin sensitivity, injection of TIMP-GLIA nanoparticles induced unresponsiveness to gliadin and reduced markers of inflammation and enteropathy. This strategy might be developed for the treatment of celiac disease.

Food immunotherapy for children with food allergies: state of the art and science

PURPOSE OF REVIEW

This review examines the current literature and provides insight into the role of food immunotherapy in the management of food-allergic children. Key food immunotherapy trials, benefits, and risks of the intervention, as well as areas requiring further study are all discussed.

RECENT FINDINGS

Research studies have reported encouraging results regarding the efficacy of food immunotherapy in desensitizing food-allergic patients with an acceptable safety profile and a documented improvement in quality of life. The role of biologics and long-term effects of food immunotherapy are still under investigation.

SUMMARY

The burden of food allergy is significant, multifaceted, and well documented. Food immunotherapy is a novel treatment option and an exciting area of research that has seen tremendous progress over the last decade, presenting encouraging results for the treatment of children with food allergies.