Background The mechanisms contributing to clinical immune tolerance remain incompletely understood. This study provides evidence for specific immune mechanisms that are associated with a model of operationally defined clinical tolerance. Objective Our overall objective was to study laboratory changes associated with clinical immune tolerance in antigen-induced T cells, basophils, and antibodies in subjects undergoing oral immunotherapy (OIT) for peanut allergy. Methods In a phase 1, single site study, we studied participants (n=23) undergoing peanut OIT and compared them to age-matched allergic controls (n=20) undergoing standard of care (abstaining from peanut) for 24 months. Participants were operationally defined as clinically immune tolerant (IT) if they had no detectable allergic reactions to a peanut oral food challenge after 3 months of therapy withdrawal (IT, n=7) while those that had an allergic reaction were categorized as non-tolerant (NT, n=13). Results Antibody and basophil activation measurements did not statistically differentiate between NT vs. IT. However, T-cell function and demethylation of FOXP3 CpG sites in antigen-induced Treg were significantly different between IT vs. NT participants. When IT participants were withdrawn from peanut therapy for an additional 3 months (total of 6 months); only 3 participants remained "immune tolerant" and 4 participants regained sensitivity along with increased methylation of FOXP3 CpG sites in antigen-induced Treg. Conclusion In summary, modifications at the DNA level of antigen-induced T-cell subsets may be predictive of a state of operationally-defined clinical "immune tolerance" during peanut OIT.

Background Although peanut oral immunotherapy (OIT) has been conclusively shown to cause desensitization, it is currently unknown whether clinical protection persists after stopping therapy. Objective Our primary objective was to determine whether peanut OIT can induce sustained unresponsiveness following withdrawal of OIT. Methods We conducted a pilot clinical trial of peanut OIT at two U.S. centers. Subjects aged 1–16 were recruited and treated for up to five years with peanut OIT. The protocol was modified over time to permit dose increases to a maximum of 4000 mg peanut protein/day. Blood was collected at multiple time points. Clinical endpoints were measured with 5000 mg double-blinded, placebo-controlled food challenges once specific criteria were met. Results Of the 39 subjects originally enrolled, 24 completed the protocol and had evaluable outcomes. 12/24 (50%) successfully passed a challenge one month after stopping OIT and achieved sustained unresponsiveness. Peanut was added to the diet. At baseline and the time of challenge, such subjects had smaller skin tests as well as lower IgE levels specific for peanut, Ara h 1, and Ara h 2, and lower ratios of peanut-specific:total IgE, compared to subjects not passing. There were no differences in peanut IgG4 levels or functional activity at end-of-study. Conclusions This is the first demonstration of sustained unresponsiveness after peanut OIT, occurring in half of subjects treated up to five years. OIT favorably modified the peanut-specific immune response in all subjects completing the protocol. Smaller skin tests and lower allergen-specific IgE levels were predictive of successful outcome.

Background Oral immunotherapy (OIT) is an effective experimental food allergy treatment that is limited by treatment withdrawal and the frequent reversibility of desensitization if interrupted. Newly-diagnosed preschool children may have clinical and immunological characteristics more amenable to treatment. Objective To test the safety, effectiveness, and feasibility of early OIT (E-OIT) in the treatment of peanut allergy. Methods We enrolled 40 children aged 9–36 months with suspected or known peanut allergy. Qualifying subjects reacted to peanut during an entry food challenge and were block-randomized 1:1 to receive E-OIT at goal maintenance doses of 300 or 3000 mg/day in a double-blinded fashion. The primary endpoint, sustained unresponsiveness at four weeks after stopping E-OIT (4-SU), was assessed by DBPCFC either upon achieving four pre-specified criteria, or after three maintenance years. Peanut-specific immune responses were serially analyzed. Outcomes were compared to 154 matched standard-care controls. Results Of 40 consented subjects, three (7.5%) did not qualify. Overall, 29/37 (78%) in the intent-to-treat analysis achieved 4-SU (300 mg arm, 17/20 [85%]; 3000 mg, 12/17 [71%], p=0.43) over a median of 29 months. Per-protocol, the overall proportion achieving 4-SU was 29/32 (91%). Peanut-specific IgE levels significantly declined in E-OIT-treated children, who were 19 times more likely to successfully consume dietary peanut than matched standard-care controls, in whom peanut-specific IgEs significantly increased (RR 19.42 [95%CI 8.7 – 43.7], p<0.001). Allergic side effects during E-OIT were common but all were mild-moderate. Conclusion At both doses tested, E-OIT had an acceptable safety profile and was highly successful in rapidly suppressing allergic immune responses and achieving safe dietary reintroduction.

Background Though peanut oral immunotherapy (OIT) is a promising investigational therapy, its potential is limited by substantial adverse events (AEs), which are relatively understudied. Objective To conduct a retrospective analysis pooling three pediatric peanut OIT trials, comprising the largest analysis of peanut OIT safety to date. Methods We pooled 104 peanut-allergic children from three peanut OIT studies. We catalogued AEs from parental report, daily symptom diaries, and dose escalations. We included events that were likely related to OIT and identified potential baseline predictors of higher AE rates using generalized linear regression models. Results Eighty percent of subjects experienced likely-related AEs during OIT (72% during buildup and 47% during maintenance). Of these AEs, over 90% occurred while at home. Approximately 42% of subjects experienced systemic reactions, and 49% experienced gastrointestinal symptoms. Twenty percent of subjects dropped out, with half (10% of overall group) due to persistent gastrointestinal symptoms. Baseline allergic rhinitis (AR), asthma, and peanut skin prick test (SPT) were significant predictors of higher overall AE rates. SPT predicted increased gastrointestinal AEs, and AR predicted increased systemic reactions. Over the course of OIT, 61% of subjects received treatment for likely-related AEs, 59% with antihistamines and 12% with epinephrine. Conclusion Peanut OIT is associated with frequent AEs, with rates declining over time, and most graded mild. However, systemic reactions and intolerable gastrointestinal AEs do occur and are significantly associated with AR and peanut SPT, respectively. Further study is needed of predictive biomarkers and the overall risks and benefits of OIT.

Parasympathetic stimulation of pancreatic islets augments glucose-stimulated insulin secretion by inducing inositol trisphosphate receptor (IP(3)R)-mediated calcium ion (Ca2+) release. Ankyrin-B binds to the IP(3)R and is enriched in pancreatic beta cells. We found that ankyrin-B-deficient islets displayed impaired potentiation of insulin secretion by the muscarinic agonist carbachol, blunted carbachol-mediated intracellular Ca2+ release, and reduced the abundance of IP3R. Ankyrin-B-haploinsufficient mice exhibited hyperglycemia after oral ingestion but not after intraperitoneal injection of glucose, consistent with impaired parasympathetic potentiation of glucose-stimulated insulin secretion. The R1788W mutation of ankyrin-B impaired its function in pancreatic islets and is associated with type 2 diabetes in Caucasians and Hispanics. Thus, defective glycemic regulation through loss of ankyrin-B-dependent stabilization of IP3R is a potential risk factor for type 2 diabetes.