Peanut oral immunotherapy results in increased antigen-induced regulatory T-cell function and hypomethylation of forkhead box protein 3 (FOXP3).

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 with age-matched allergic control subjects (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), whereas those who had an allergic reaction were categorized as nontolerant (NT; n = 13). RESULTS: Antibody and basophil activation measurements did not statistically differentiate between NT versus IT participants. However, T-cell function and demethylation of forkhead box protein 3 (FOXP3) CpG sites in antigen-induced regulatory T cells were significantly different between IT versus NT participants. When IT participants were withdrawn from peanut therapy for an additional 3 months (total of 6 months), only 3 participants remained classified as IT participants, and 4 participants regained sensitivity along with increased methylation of FOXP3 CpG sites in antigen-induced regulatory T cells. CONCLUSION: In summary, modifications at the DNA level of antigen-induced T-cell subsets might be predictive of a state of operationally defined clinical immune tolerance during peanut OIT.

Identification of STAT5A and STAT5B target genes in human T cells.

Signal transducer and activator of transcription (STAT) comprises a family of universal transcription factors that help cells sense and respond to environmental signals. STAT5 refers to two highly related proteins, STAT5A and STAT5B, with critical function: their complete deficiency is lethal in mice; in humans, STAT5B deficiency alone leads to endocrine and immunological problems, while STAT5A deficiency has not been reported. STAT5A and STAT5B show peptide sequence similarities greater than 90%, but subtle structural differences suggest possible non-redundant roles in gene regulation. However, these roles remain unclear in humans. We applied chromatin immunoprecipitation followed by DNA sequencing using human CD4(+) T cells to detect candidate genes regulated by STAT5A and/or STAT5B, and quantitative-PCR in STAT5A or STAT5B knock-down (KD) human CD4(+) T cells to validate the findings. Our data show STAT5A and STAT5B play redundant roles in cell proliferation and apoptosis via SGK1 interaction. Interestingly, we found a novel, unique role for STAT5A in binding to genes involved in neural development and function (NDRG1, DNAJC6, and SSH2), while STAT5B appears to play a distinct role in T cell development and function via DOCK8, SNX9, FOXP3 and IL2RA binding. Our results also suggest that one or more co-activators for STAT5A and/or STAT5B may play important roles in establishing different binding abilities and gene regulation behaviors. The new identification of these genes regulated by STAT5A and/or STAT5B has major implications for understanding the pathophysiology of cancer progression, neural disorders, and immune abnormalities.

Cerebellar Purkinje cell activity drives motor learning.

The climbing fiber input to the cerebellar cortex is thought to provide instructive signals that drive the induction of motor skill learning. We found that optogenetic activation of Purkinje cells, the sole output neurons of the cerebellar cortex, can also drive motor learning in mice. This dual control over the induction of learning by climbing fibers and Purkinje cells can expand the learning capacity of motor circuits.

Food allergy diagnosis and therapy: where are we now?

Food allergy is a growing worldwide epidemic that adversely effects up to 10% of the population. Causes and risk factors remain unclear and diagnostic methods are imprecise. There is currently no accepted treatment for food allergy. Therefore, there is an imminent need for greater understanding of food allergies, revised diagnostics and development of safe, effective therapies. Oral immunotherapy provides a particularly promising avenue, but is still highly experimental and not ready for clinical use.

Asthma discordance in twins is linked to epigenetic modifications of T cells.

T cells mediate the inflammatory responses observed in asthma among genetically susceptible individuals and have been suspected to be prone to epigenetic regulation. However, these relationships are not well established from past clinical studies that have had limited capacity to control for the effects of variable genetic predisposition and early environmental exposures. Relying on a cohort of monozygotic twins discordant for asthma we sought to determine if epigenetic modifications in T cells were associated with current asthma and explored whether such modifications were associated with second hand smoke exposures. Our study was conducted in a monozygotic twin cohort of adult twin pairs (n = 21) all discordant for asthma. Regulatory T cell (Treg) and effector T cell (Teff) subsets were assessed for levels of cellular function, protein expression, gene expression and CpG methylation within Forkhead box P3 (FOXP3) and interferon gamma-γ (IFNγ) loci. Comparisons by asthma and current report of exposure to second hand smoke were made. Treg from asthmatic discordant twins demonstrated decreased FOXP3 protein expression and impaired Treg function that was associated with increased levels of CpG methylation within the FOXP3 locus when compared to their non-asthmatic twin partner. In parallel, Teff from discordant asthmatic twins demonstrated increased methylation of the IFNγ locus, decreased IFNγ expression and reduced Teff function when compared to Teff from the non-asthmatic twin. Finally, report of current exposure to second hand smoke was associated with modifications in both Treg and Teff at the transcriptional level among asthmatics. The results of the current study provide evidence for differential function of T cell subsets in monozygotic twins discordant for asthma that are regulated by changes in DNA methylation. Our preliminary data suggest exposure to second hand smoke may augment the modified T cell responses associated with asthma.

Secondhand smoke in combination with ambient air pollution exposure is associated with increasedx CpG methylation and decreased expression of IFN-γ in T effector cells and Foxp3 in T regulatory cells in children.

BACKGROUND: Secondhand smoke (SHS) and ambient air pollution (AAP) exposures have been associated with increased prevalence and severity of asthma and DNA modifications of immune cells. In the current study, we examined the association between SHS and AAP with DNA methylation and expression of interferon-gamma (IFN-γ) and forkhead box protein 3 (Foxp3) in T cell populations. METHODS: Subjects 7-18 years old were recruited from Fresno (high AAP; n = 62) and Stanford, CA (low AAP; n = 40) and divided into SHS-exposed (Fresno: n = 31, Stanford: n = 6) and non-SHS-exposed (nSHS; Fresno: n = 31, Stanford: n = 34) groups. T cells purified from peripheral blood were assessed for levels of DNA methylation and expression of IFN-γ (in effector T cells) or Foxp3 (in regulatory T cells). RESULTS: Analysis showed a significant increase in mean % CpG methylation of IFN-γ and Foxp3 associated with SHS exposure (IFN-γ: FSHS 62.10%, FnSHS 41.29%, p < 0.05; SSHS 46.67%, SnSHS 24.85%, p < 0.05; Foxp3: FSHS 74.60%, FnSHS 54.44%, p < 0.05; SSHS 62.40%, SnSHS 18.41%, p < 0.05) and a significant decrease in mean transcription levels of both genes (IFN-γ: FSHS 0.75, FnSHS 1.52, p < 0.05; SHS 2.25, nSHS 3.53, p < 0.05; Foxp3: FSHS 0.75, FnSHS 3.29, p < 0.05; SSHS 4.8, SnSHS 7.2, p < 0.05). AAP was also associated with hypermethylation (IFN-γ: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05; Foxp3: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05) and decreased transcription of both genes (IFN-γ: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05; Foxp3: FSHS vs. SSHS, p < 0.05; FnSHS vs. SnSHS, p < 0.05). Average methylation between AAP- and SHS-only exposures was not significantly different (IFN-γ: p = 0.15; Foxp3: p = 0.27), nor was Foxp3 expression (p = 0.08); IFN-γ expression was significantly decreased in AAP-only subjects (p < 0.05). CONCLUSIONS: Exposures to SHS and AAP are associated with significant hypermethylation and decreased expression of IFN-γ in Teffs and Foxp3 in Tregs. Relative contributions of each exposure to DNA modification and asthma pathogenesis warrant further investigation.

Oral immunotherapy and anti-IgE antibody-adjunctive treatment for food allergy.

One of the most promising therapies for food allergy is oral immunotherapy (OIT), in which small amounts of allergen are administered in increasing amounts, with the immediate goal of desensitization and the long-term goal of tolerance. However, safety and standardization concerns prevent its widespread use, and a subgroup of patients may experience severe allergic reactions. These concerns might be addressed by another promising therapy involving anti-IgE monoclonal antibodies (mAb), which can reduce allergic reactions associated with food administration. A recent pilot study combining anti-IgE mAb with OIT suggests that anti-IgE mAb might improve the safety, rapidity, and efficacy of OIT.