CLC- a novel susceptibility gene for allergic rhinitis?

BACKGROUND: Studies of the nasal lavage fluid proteome have previously identified proteins differently expressed in patients with symptomatic allergic rhinitis, e.g. S100A7, prolactin-inducible protein (PIP), wingless-type MMTV integration site family, member 2B (WNT2B), Charcot-Leyden crystal protein (CLC) and palate lung nasal epithelial clone (PLUNC). The aim of the present study was to investigate if genetic variation associated with allergic rhinitis can be found in these genes. METHODS: Peripheral blood was collected from 251 patients with birch and/or grass pollen-induced allergic rhinitis and 386 nonatopic healthy controls. A total of 39 single nucleotide polymorphisms (SNPs) distributed over the genes PIP, WNT2B, CLC and PLUNC were selected from dbSNP, genotyped and investigated for associations with allergic rhinitis. Twelve additional SNPs were subsequently analysed for CLC. RESULTS: All 22 investigated SNPs in CLC were polymorphic. Ten SNPs yielded significant differences between cases and controls with respect to genotype frequencies. Homozygotes for the minor allele were more common in allergic individuals compared to healthy controls. The minor alleles of these SNPs were all located on the same haplotype. Furthermore, homozygotes for the minor allele of two of the promoter SNPs had higher average scores for birch in skin prick test. In contrast, for seven SNPs within the gene, heterozygotes and homozygotes for the major allele had higher average scores for grass. None of the other three genes showed association. CONCLUSION: Genetic variation in CLC was found to be associated with allergic rhinitis. The pattern of variation is compatible with a recessive inheritance model and the previously observed altered protein levels detected in patients with allergic rhinitis.

Interleukin-4 increases murine airway response to kinins, via up-regulation of bradykinin B1-receptors and altered signalling along mitogen-activated protein kinase pathways.

BACKGROUND: IL-4 is believed to play a role in asthma and chronic obstructive pulmonary disease through promotion of eosinophilic inflammation and mucus hypersecretion. Whether IL-4 can induce a direct effect on airway smooth muscle remains unknown. OBJECTIVE: To investigate the effect of IL-4 on airway smooth muscle, focusing on the contractile response to des-Arg9-bradykinin and bradykinin. METHODS: Tracheal segments from murine airways were cultured for 1-8 days in the absence and presence of IL-4. The smooth muscle response induced by des-Arg9-bradykinin and bradykinin was investigated in myographs. Expression levels for the IL-4-, bradykinin B1- and B2-receptors were characterized using RT-PCR. Specific inhibitors were used to study signal changes along the IL-4 receptor- (IL-4R-) coupled mitogen-activated protein (MAP) kinase (MAPK) pathways. RESULTS: IL-4 treatment increased the contractile response to des-Arg9-bradykinin and bradykinin in a concentration- and time-dependent manner. Dexamethasone and the transcriptional inhibitor actinomycin D blocked this effect. c-Jun N-terminal kinase inhibitor SP600125 also blocked the effect of both des-Arg9-bradykinin and bradykinin, whereas p38 inhibitor SB203580 blocked only the former and the MAPKK inhibitor PD098059, only the latter agonist responses. IL-4 treatment increased the mRNA levels representing bradykinin B1- but not B2-receptors. Levels of IL-4R were not altered during culture. CONCLUSION: Long-term exposure to IL-4 increases the contractile response induced by des-Arg9-bradykinin and bradykinin in cultured murine airways. This effect appears to be mediated via an up-regulation of B1-receptors and altered signalling along the MAPK pathways.