Background: Humans are subjected to various environmental stressors (bacteria, viruses, pollution) throughout life. As such, an inherent relationship exists between the effect of these exposures with age. The impact of these environmental stressors can manifest through DNA methylation (DNAm). However, whether these epigenetic effects selectively target genes, pathways, and biological regulatory mechanisms remains unclear. Due to the frequency of human rhinovirus (HRV) infections throughout life (particularly in early development), we propose the use of HRV under controlled conditions can model the effect of multiple exposures to environmental stressors.
Methods: We generated a prediction model by combining transcriptome and DNAm datasets from human epithelial cells after repeated HRV infections. We applied a novel experimental statistical design and method to systematically explore the multifaceted experimental space (number of infections, multiplicity of infections and duration). Our model included 35 samples, each characterized by the three parameters defining their infection status.
Results: Trainable genes were defined by a consistent linear directionality in DNAm and gene expression changes with successive infections. We identified 77 trainable genes which could be further explored in future studies. The identified methylation sites were tracked within a pediatric cohort to determine the relative changes in candidate-trained sites with disease status and age.
Conclusions: Repeated viral infections induce an immune training response in bronchial epithelial cells. Training-sensitive DNAm sites indicate alternate divergent associations in asthma compared to healthy individuals. Our novel model presents a robust tool for identifying trainable genes, providing a foundation for future studies.
Introduction: Basophil activation test (BAT) might be an alternative to nasal allergen challenge (NAC) to identify the allergic etiology in rhinitis patients. Here, we investigate the diagnostic performance of BAT for allergic phenotypes of rhinitis.
Methods: Rhinitis patients and healthy controls were subjected to NAC with Dermatophagoides pteronyssinus (DP), Alternaria alternata (AA), grass (GP) and olive (OP) pollens. Rhinitis subjects also underwent skin prick test (SPT) with relevant allergens. Patients were classified into allergic rhinitis (AR, positive NAC and SPT), local allergic rhinitis (LAR, positive NAC and negative SPT), dual allergic rhinitis (DAR, defined as AR for ≥1 allergen and LAR for ≥1 allergen), and non-allergic rhinitis (NAR, negative NAC and SPT) phenotypes. BAT with DP, AA, GP and OP was conducted in study individuals and compared with NAC results.
Results: A total of 47 AR, 31 DAR, 26 LAR, 12 NAR and 21 control subjects were recruited. The best positivity cut-offs of BAT for DP-, AA-, GP- and OP-driven allergy (all phenotypes) were a %CD63 cells of 8.650, 14.250, 26.200, and 12.780, respectively (AUC 0.851, 0.701, 0.887, and 0.921, respectively). Sensitivity, specificity, negative and positive predictive values of BAT (all phenotypes) ranged 43.5%(AA)-83.3%(OP), 88.9%(GP)-100%(AA), 87%(GP)-100%(AA), and 61.1%(DP)-80.0%(pollens), respectively. BAT identified 79%-100% of SPT-positive allergies (AR and DAR), and 25%-75% of SPT-negative allergies (LAR and DAR), while ≤10% of NAR/HC subjects tested positive. BAT positivity correlated with rhinitis severity in LAR patients (p = 0.018), and associated with conjunctivitis (p = 0.015) in allergic subjects.
Conclusion: BAT can replace NAC for AR confirmation, and limit the number of NAC required for LAR and DAR diagnosis. BAT can demonstrate sIgE in SPT-negative allergies.