Early priming of the immune system: Identifying predictive markers of innate immunity and calcium signalling for the development of asthma

Anselm, Bettina (2019): Early priming of the immune system: Identifying predictive markers of innate immunity and calcium signalling for the development of asthma. Dissertation, LMU München: Medizinische Fakultät

Abstract

Asthma remains one of the most common chronic diseases in childhood, developing already early in life. In the first year of life, children start to present with wheeze, which is currently classified as multi-trigger or viral-wheeze based on specific triggers and their long-term time course. An early prediction of children with wheeze and at risk for subsequent asthma is currently difficult and underlying immune mechanisms of distinct wheeze phenotypes are unknown. As early priming of the immune system occurs already prenatally, we aim to identify predictive markers for children at risk for subsequent development of childhood wheeze and asthma. From previous work of our research group, innate immune regulation, in particular antiviral immunity (LY75, CD209, IPS1) and Ca2+-signalling pathways, e.g. CALM2 and genes related to store-operated calcium entry (ITPR2, STIM2, ORAI1, ORMDL3 and ATP2A3) have been shown to be differentially expressed between asthmatics and healthy children during disease manifestation at school-age. Here, we aimed to assess these genes at the earliest time point, namely at birth. We investigated gene regulation as potential predictive markers for the development of subsequent wheeze phenotypes. The mRNA-expression of selected candidate genes of Ca2+-signalling (CALM2, ITPR2, ORAI1, STIM2, ORMDL3, ATP2A3) and innate immunity (CD209, LY75, FPR2, IPS1) was measured in CBMCs of children with subsequent wheeze phenotypes compared to healthy children (HC). Children were selected from the PAULINA/PAULCHEN cohort (n=200). Phenotypic classification in multitrigger, persistent viral or early viral wheeze and healthy control was based on clinical information from questionnaires answered by the parents at age 3 and/or 6 years. Previously, cord blood was taken from healthy neonates with strict inclusion criteria, and CBMCs were isolated within 24 hours, kept unstimulated or were stimulated with PHA or LpA for 72h. Gene expression at mRNA level was assessed via qRT-PCR, and analysed with the Wilcoxon rank sum test. The following results were obtained and are presented in this thesis: 1. Expression of all candidate genes of calcium signalling and viral innate immunity was detectable and varied significantly or trend-wise between the different wheeze subgroups and healthy controls (mainly ITPR2, CALM2, ORAI1, STIM2, FPR2, IPS1, LY75). 2. Children with persistent viral wheeze showed a lower expression of the candidate 103 genes (ITPR2, CALM2, ORAI1, STIM2, ATP2A3, IPS1, LY75, CD209) than the other wheeze subgroups. 3. Children with persistent multitrigger wheeze showed a distinct pattern of elevated expression for the candidate genes (ITPR2, CALM2, ORAI1, STIM2, ORMDL3, ATP2A3, S100A9 FPR2, IPS1, LY75, CD209). This was visible for the whole calcium-signalling pathway, supporting the view of persistent multitrigger wheeze as distinct entity and suggests a pathophysiological relevance of calcium signalling. 4. Despite parallels in clinical presentation, late-onset multitrigger wheeze share gene expression patterns with persistent viral rather than persistent multitrigger wheeze, suggesting a different underlying pathophysiology. Taken together, these results affirm the emerging view of childhood asthma as a complex disease and show that differences in immune regulation are already visible at birth. Importantly, especially the findings for persistent multitrigger wheeze could eventually, after suitable validation for example in a larger cohort with higher case numbers, help in the development of specific biomarkers before disease manifestation, which may contribute to closer clinical monitoring and in the long-term potentially to a change in therapy for patients with distinct phenotypes of childhood asthma.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: Asthma, Childhood, Calcium Signaling, Innate Immunity
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften ; 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• Fakultäten: Medizinische Fakultät
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 12. Dezember 2019
• 1. Bericht­erstatter:in: Schaub, Bianca