Joint transcriptomic and cytometric study of peanut allergic children reveals molecular and cellular cross-talk in reaction thresholds

BACKGROUND

Reaction thresholds in peanut allergy are highly variable. Elucidating causal relationships between molecular and cellular processes associated with variable thresholds could point to therapeutic pathways for raising thresholds.

OBJECTIVE

To characterize molecular and cellular systemic processes associated with reaction threshold in peanut allergy and causal relationships between them.

METHODS

105 children ages 4 to 14 years with suspected peanut allergy underwent double-blind, placebo-controlled food challenges to peanut. The cumulative peanut protein quantity eliciting allergic symptoms was considered the reaction threshold for each child. Peripheral blood samples collected at 0, 2, and 4 hours after challenge start were used for RNA sequencing, whole blood staining, and cytometry. Statistical and network analyses were performed to identify associations and causal mediation between the molecular and cellular profiles and peanut reaction threshold.

RESULTS

Within the cohort (n=105), 81 (77%) experienced allergic reactions after ingesting varying quantities of peanut, ranging from 43 to 9043 mg cumulative peanut protein. Peripheral blood expression of transcripts (e.g., IGF1R, FDR=5.4e-5 and PADI4, FDR=5.4e-5) and neutrophil abundance (FDR=9.5e-4) were associated with peanut threshold. Co-expression network analyses revealed that the threshold-associated transcripts were enriched in modules for FcγR-mediated phagocytosis (FDR=3.2e-3) and TLR (FDR=1.4e-3) signaling. Bayesian network, key driver, and causal mediation analyses identified key drivers (AP5B1, KLHL21, VASP, TPD52L2 and IGF2R) within these modules involved in bi-directional causal mediation relationships with neutrophil abundance.

CONCLUSION

Key driver transcripts in FcγR-mediated phagocytosis and TLR signaling bi-directionally interact with neutrophils in peripheral blood and are associated with reaction threshold in peanut allergy.