Abstract

Background. Viral respiratory infections are the leading cause of hospitalization in young children, especially by respiratory syncytial virus (RSV). Additionally, obesity has been associated with a worse clinical course in viral infection. In Chile, childhood obesity reaches 34%. This pathology is characterized by a low-grade chronic inflammatory state, due to increased production of pro-inflammatory cytokines, among them leptin. In adults, leptin has been reported to increase levels of proteins the suppressors of cytokine signaling (SOCS), which may potentially alter the production of antiviral proteins and interferons (IFNs), triggering a poor antiviral response. Thus, the objective of this study was to measure the expression of SOCS in obese children and its association with a lower antiviral response induced by lipopolysaccharide (LPS) in isolated peripheral blood mononuclear cells (PBMC). Methods. SOCS1 and SOCS3 mRNA levels were measured from PBMC of 3 obese children and 3 normal weight children, all under 2 years old. SOCS, IFN-γ and 2´,´5-oligoadenylate synthetase (OAS) antiviral response gene were quantified in PBMC cultures, in response to TLR4 stimulation with LPS (1 µg/ml). Also, PBMC of one normal weight child were stimulated with LPS (1 µg/ml) and leptin (100 ng/µl) and expression of OAS and quantification IFN-γ was analysed. mRNA of SOCS and OAS was evaluated by qRT-PCR. Leptin and IFN-γ was analysed in plasma and culture by Magnetic Luminex®assay. Results. Obese children had a higher SOCS3 expression (p <0.049) than normal weight children, but not SOCS1. No significant differences were found in plasma leptin production (M 2.5 ng/mL, 1.0-6.3) or in the expression of SOCS1 and 3, OAS and IFN-γ in PBMC cultures of obese children compared to normal weight children. However, PBMC of normal weight child stimulated with LPS and leptin showed a decreased level of expression of OAS and IFN-γ. Conclusion. Obese children present higher levels of SOC3 protein expression in blood PBMC than normal weight children. However, upon LPS stimulation only of obese children PBMC, despite a trend, there was no significant decrease in IFN-γ and OAS gene expression, probably due to the lack of leptin in the medium.