Peripheral blood mononuclear cell transcriptome profile in a clinical trial with subcutaneous, grass pollen allergoid immunotherapy.

INTRODUCTION: Allergen-specific immunotherapy (AIT) is the only disease-modifying treatment in allergic airway diseases. Underlying immunological mechanisms and candidate biomarkers, which may be translated into predictive/surrogate measures of clinical efficacy, remain an active area of research. The aim of this study was to evaluate Pollinex Quattro (PQ) Grass AIT induced immunomodulatory mechanisms, based on transcriptome profiling of peripheral blood mononuclear cells. METHODS: 119 subjects with grass pollen induced seasonal allergic rhinitis (SAR) were randomized in a 2:2:1:1 ratio to receive a cumulative dose of PQ Grass as a conventional or extended pre-seasonal regimen, placebo, or placebo with MicroCrystalline Tyrosine. Gene expression analysis was an exploratory endpoint evaluated in a subgroup of 30 subjects randomly selected from the four treatment arms. Samples were collected at three time points: screening (baseline), before the start of the grass pollen season and at the end of the season. This study was funded by the manufacturer of PQ. RESULTS: Transcriptome analysis demonstrated that the most significant changes in gene expression, for both treatment regimens, were at the end of the grass pollen season, with the main Th1 candidate molecules (IL-12A, IFNγ) upregulated and Th2 signature cytokines downregulated (IL-4, IL-13, IL-9) (p < .05). Canonical pathways analysis demonstrated Th1, Th2, Th17 and IL-17 as the most significantly enriched pathways based on absolute value of activation z-score (IzI score ≥ 2, p < .05). Upstream regulator analysis showed pronounced inhibition of pro-inflammatory allergic molecules IgE, IL-17A, IL-17F, IL-25 (IL-17E) (IzI score ≥ 2, FDR < 0.05) and activation of pro-tolerogenic molecules IL-12A, IL-27, IL-35 (EBI3) at the end of the grass pollen season. CONCLUSION: Peripheral blood mononuclear cells transcriptome profile showed an inhibition of Th2, Th17 pro-inflammatory allergic responses and immune deviation towards Th1 responses. PQ Grass extended regimen exhibited a superior mechanistic efficacy profile in comparison with PQ conventional regimen.

On the role of antibody affinity and avidity in the IgE-mediated allergic response.

Type I hypersensitivity, also known as classical allergy, is mediated via allergen-specific IgE antibodies bound to type I FcR (FcεRI) on the surface of mast cells and basophils upon cross-linking by allergens. This IgE-mediated cellular activation may be blocked by allergen-specific IgG through multiple mechanisms, including direct neutralization of the allergen or engagement of the inhibitory receptor FcγRIIb which blocks IgE signal transduction. In addition, co-engagement of FcεRI and FcγRIIb by IgE-IgG-allergen immune complexes causes down regulation of receptor-bound IgE, resulting in desensitization of the cells. Both, activation of FcεRI by allergen-specific IgE and engagement of FcγRIIb by allergen-specific IgG are driven by allergen-binding. Here we delineate the distinct roles of antibody affinity versus avidity in driving these processes and discuss the role of IgG subclasses in inhibiting basophil and mast cell activation.

Transcriptome analysis and safety profile of the early-phase clinical response to an adjuvanted grass allergoid immunotherapy.

BACKGROUND: Specific immunotherapy is the only type of disease-modifying treatment, which induces rapid desensitization and long-term sustained unresponsiveness in patients with seasonal allergic rhinoconjunctivitis. The safety and tolerability of a new cumulative dose regimen of 35600 SU Grass MATA MPL for subcutaneous immunotherapy were assessed in pre-seasonal, single-blind, placebo controlled Phase I clinical study. Underlying immunological mechanisms were explored using transcriptome analysis of peripheral blood mononuclear cells. METHODS: Study subjects with a history of moderate to severe seasonal allergic rhinitis and/or conjunctivitis (SAR) due to grass (Pooideae) pollen exposure were randomized on a 1:1 ratio to receive either six 1.0 mL injections of cumulative dose regimen 35600 SU of Grass MATA MPL or placebo. The study consisted of three periods: screening, randomization and treatment and End of Study period. Blood samples were taken for clinical safety laboratory assessments and for the assessment of gene expression analysis during screening visit and End of Study visit. The safety statistics was calculated using Fisher's exact test. Delta Delta Ct method analysis of RT2 Profiler PCR Array gene expression results was used to calculate changes in gene expression level. Genes with the absolute value of log2 fold change greater than ±1.1 and p-value less than 0.05 were identified as differentially expressed and underwent IPA data analysis. RESULTS: The results of the study indicated that the higher cumulative dose regimen of the immunotherapy was well-tolerated. Changes in gene expression profile were associated with early immune responses implicating innate and adaptive immune mechanisms. Pathways and mechanistic network analysis via IPA mapped differentially expressed genes onto canonical pathways related to T cell differentiation, cytokine signalling and Th1/Th2 activation pathways. The transcriptome findings of the study could be further verified in large-scale field studies in order to explore their potential as predictive markers of successful immunotherapy. CONCLUSIONS: The higher dose cumulative regime 35600 SU of Grass MATA MPL vaccine was well tolerated and safe. Molecular markers IL-27, IL-10, IL-4, TNF, IFNγ, TGFß and TLR4 were the main predicted molecular drivers of the observed gene expression changes following early stages of SIT with Grass MATA MPL immunotherapy.