Progress in allergy signal research on mast cells: systemic approach to mast cell biology in allergic diseases

Peripheral blood RNA gene expression profiling in patients with bacterial meningitis

OBJECTIVES

The aim of present study was to find genetic pathways activated during infection with bacterial meningitis (BM) and potentially influencing the course of the infection using genome-wide RNA expression profiling combined with pathway analysis and functional annotation of the differential transcription.

METHODS

We analyzed 21 patients with BM hospitalized in 2008. The control group consisted of 18 healthy subjects. The RNA was extracted from whole blood, globin mRNA was depleted and gene expression profiling was performed using GeneChip Human Gene 1.0 ST Arrays which can assess the transcription of 28,869 genes. Gene expression profile data were analyzed using Bioconductor packages and Bayesian modeling. Functional annotation of the enriched gene sets was used to define the altered genetic networks. We also analyzed whether gene expression profiles depend on the clinical course and outcome. In order to verify the microarray results, the expression levels of ten functionally relevant genes with high statistical significance (CD177, IL1R2, IL18R1, IL18RAP, OLFM4, TLR5, CPA3, FCER1A, IL5RA, and IL7R) were confirmed by quantitative real-time (qRT) PCR.

RESULTS

There were 8569 genes displaying differential expression at a significance level of p < 0.05. Following False Discovery Rate (FDR) correction, a total of 5500 genes remained significant at a p-value of < 0.01. Quantitative RT-PCR confirmed the differential expression in 10 selected genes. Functional annotation and network analysis indicated that most of the genes were related to activation of humoral and cellular immune responses (enrichment score 43). Those changes were found in both adults and in children with BM compared to the healthy controls. The gene expression profiles did not significantly depend on the clinical outcome, but there was a strong influence of the specific type of pathogen underlying BM.

CONCLUSION

This study demonstrates that there is a very strong activation of immune response at the transcriptional level during BM and that the type of pathogen influences this transcriptional activation.

An 18-year follow-up of allergy development related to nasal metachromatic cell findings during infancy

BACKGROUND

The ability to predict the development of allergic diseases in infants is important. Predictive biomarkers are wanted to improve the risk evaluation in addition to known heredity of allergy. Biomarkers taken during infancy need to be evaluated through longitudinal studies into adulthood. The objective of this study was to analyse the occurrence of metachromatic cells in the nasal mucosa during infancy (MC(infancy)) and evaluate the cells as predictive biomarkers of allergy development.

METHODS

Previously, MC(infancy) occurrences were analysed in 64 infants with and without allergy heredity, and related to allergy development at 18 months and 6 years of age. In this third follow-up at 18 years of age, current allergy symptoms were analysed. MC(infancy) findings were related to the cumulative number of allergic subjects. The predictive values of MC(infancy) and known heredity were compared.

RESULTS

The cumulative number of subjects with allergy was 46, probable allergy 5, and no allergy 13. Detected MC(infancy) predicted allergy with high accuracy (31/33), but negative MC(infancy) findings did not exclude the risk (15/31). In the group of allergic subjects positive MC(infancy) were found in 31/46 (67%), positive heredity in 37/46 (80%) and one/both factors positive in 43/46 (93%). Detection of MC(infancy) could precede the debut of allergy symptoms by many years.

CONCLUSIONS

Detected MC(infancy) predicted allergy development, but absence of MC(infancy) did not exclude the risk, and therefore this biomarker was not found to be adequate. There is a further need to find biomarkers with high ability to both predict and exclude the risk.