Background: Copy number of Chemokine ligand 3-like 1 (CCL3L1) is associated with various immune disorders. This study was conducted to assess the role of CCL3L1 in asthma by both association analyses of human subjects and in vitro functional analyses.
Methods: We analyzed the copy number of the CCL3L1 gene in 533 Korean subjects (372 controls and 161 asthma patients) by real-time PCR, and investigated the effect of recombinant CCL3L1 protein on THP-1 human monocytic cells that were stimulated with house dust mite extract.
Results: The mean copy number of CCL3L1 in asthma subjects was significantly lower than that of control subjects (3.18 vs. 3.75, p=0.001). A low copy number of ≤1 was significantly associated with increased asthma risk with an odds ratio of 2.47, and a high copy number of ≥5 was associated with decreased asthma risk with an odds ratio of 0.40. Subjects with ≤1 copy of CCL3L1 had significantly lower mRNA levels of CCL3L1 in peripheral blood cells, and significantly higher serum IgE levels (p<0.05). In the house dust mite extract-simulated THP-1 monocytic cells, CCL3L1 protein dose-dependently up-regulated the expression of IL-10, an anti-inflammatory cytokine.
Conclusion: Copy number of CCL3L1 may influence asthma risk by modulating IL-10 expression.
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