ABSTRACT
BACKGROUND: Elevated circulating levels of YKL-40 correlate with disease severity in Cystic Fibrosis (CF), but the role of YKL-40 in the inflammatory response in CF is still under investigation. Our main goal was to evaluate if YKL-40 can modulate the expression of major cytokines (IL-6, IL-10, IL-13) implicated in the inflammatory response in CF. A secondary goal was to explore the interactions between YKL-40 and other circulating proteins to determine the impacts on cytokine modulation. METHOD: Peripheral blood mononuclear cells (PBMCs) were isolated from the blood of 83 adult CF patients in stable clinical condition. PBMCs were treated with human YKL-40 followed by the measure of IL-6, IL-10 and IL-13 gene expression. Protein arrays were used to explore the interactions between YKL-40 and circulating proteins. Interaction with Galectin-3 (GAL3) was identified, and confirmed by binding assay. Cytokine gene expressions were again monitored by RT-qPCR after PBMC treatment with GAL3, with or without YKL-40 co-stimulation. RESULTS: Following YKL-40 stimulation, PBMC gene expression of IL-6, IL-10 and IL-13 varies across patients. IL-6 and IL-13 are coexpressed, but this response was different in male and female patients. GAL3 protein was detected in the blood of CF patients, and a molecular interaction with YKL-40 was identified. GAL3 did not interfere with the YKL-40 stimulation of IL-6, IL-10 and IL-13 but may modulate the coexpression. CONCLUSION: We observed that YKL-40 stimulation had a variable impact on IL-6, IL-10, and IL-13 gene expression in CF PBMCs and uncovered an interaction between GAL3 and YKL-40 in the serum of CF patients. Our findings suggest that YKL-40 is not only a biomarker of disease severity in CF, but it might play an active role in the inflammatory pathophysiology of the disease.
