Overexpression of YKL40,IL-6, IL-8, TNF-α in tonsils and the role of YKL40 in childhood with obstructive sleep apnea syndrome

Abstract

To evaluate the levels of YKL40, IL-6(interleukin-6), IL-8(interleukin-8), IL-10(interleukin-10), TNF-α (tumor necrosis factor-α) in OSAS (obstructive sleep apnea syndrome)children and explore the mechanism of YKL40 promoting inflammatory factors overexpression in tonsils. qPCR and ELISA were used to identify the expression of YKL40, IL-6, IL-8, IL-10, and TNF-α in the tonsils of OSAS children. Primary tonsil lymphocytes (PTLCs) were cultured and recombinant human YKL40(rhYKL40)was used to stimulate PTLCs in different concentrations and at different time points. The activation of NF-κB in PTLCs was screened by western blotting. Relative mRNA of YKL40, IL-6, IL-8, TNF-α was over expressed in OSAS-derived tonsil tissue and the levels of YKL40, IL-6, IL-8, and TNF-α was increased in OSAS-derived protein supernatant of tonsil tissue.The relative mRNA expression of IL-6, IL-8 and TNF-α increased under the treatment of YKL40 (100 ng/mmol for 24 h). The phosphorylation of p65 in NF-κB pathway was stimulated in the process. The levels of YKL40, IL-6, IL-8, and TNF-α increases in OSAS children, and YKL40 promotes the overexpression of IL-6, IL-8 and TNF-α in PTLCs via NF-κB pathway. The result implements that inflammation may play an important role in the pathogenesis of OSAS in children.

Keywords: Inflammatory factors; Interleukin; NF-κB pathway; Obstructive sleep apnea syndrome; YKL40/ CHI3L1.

Fig. 1

Relative mRNA expression and the correlations of inflammatory mediators. a Relative mRNA expression of YKL40 in PS and OSAS groups (**P < 0.01). b Relative mRNA expression of IL-6 in PS and OSAS groups (* P < 0.05), c Relative mRNA expression of IL-8 in PS and OSAS groups (* P < 0.05) d Relative mRNA expression of IL-10 in PS and OSAS groups (ns P > 0.05) e Relative mRNA expression of TNF-α in PS and OSAS group (**P < 0.01). f Correlations among the inflammatory factors(* P < 0.05,**P < 0.01).

Fig. 2

The effect of YKL40/CHI3L1 with different time points on IL-6, IL-8, IL-10, and TNF-α mRNA in PTLCs. PTLCs were stimulated with rhYKL40 (100 ng/ml) at different time points as indicated. YKL40 stimulated the expression of IL-6 mRNA(a), IL-8 mRNA (b), IL-10 mRNA (c) and TNF-α mRNA (d) (**P < 0.01, ***P < 0.001, ns-P > 0.05).

Fig. 3

The effect of YKL40/CHI3L1 with different concentrations on IL-6, IL-8, IL-10, and TNF-α mRNA expression in PTLCs. PTLCs were stimulated with rhYKL40 (24 H) at various concentrations as indicated. YKL40 stimulated the expression of IL-6 mRNA(a), IL-8 mRNA (b), IL-10 mRNA (c), and TNF-α mRNA (d) in PTLCs.(* P < 0.05,**P < 0.01, ns-P > 0.05).

Fig. 4

Involvement of p65 phosphorylation in PTLCs. a. Representative P-P65, P65 and β-actin blots in Con, rhYKL40, 3-oxo, Bay groups. b. Statistical plots between the four groups. The quantification of phosphorylated P65 was normalized by β-actin blots.(n = 6, ns P > 0.05,* P < 0.05,**P < 0.01).

Fig. 5

IL-6, IL-8, IL-10, TNF-α mRNA relative expression in different treatment of PTLCs. MRNA relative expression in Con(Control), rhYKL40, 3-oxo and Bay. IL-6 mRNA(a), IL-8 mRNA (b), IL-10 mRNA(c), TNF-α mRNA (d) ( ns, P > 0.05, *P < 0.05, **P < 0.01, *** P < 0.001).