FOXP3 Polymorphism and gene expression in Italian patients with Kawasaki Syndrome

Background

The transcription factor FOXP3 is a key regulator of immune homeostasis of natural regulatory T lymphocytes (Treg). Aim of our study was to investigate the link between the FOXP3 gene expression and polymorphism, and Kawasaki Syndrome (KS).

Materials and methods

The single nucleotide polymorphism (SNP) at position 543 of exon 5 of FOXP3 was investigated in 58 caucasian children patients with KS (F:30, M:28), recruited at our Paediatric Reumatology Unit. In 6 patients we could evaluate the percentage of circulating CD4+ T cells co-expressing CD25 and FOXP3 by flow cytometry, mRNA transcripts of FOXP3 in PBMCs by Real Time PCR (with Rnase P as internal control gene), and the levels of IL-17 in PBMCs supernatants (5 × 104 cells) by a quantitative immunoassay Kit.

Results

In KS subject, 2 females (3.4%) showed the 543 SNP in heterozygosis (C>T), as actually reported in healthy european females (4.3%). FOXP3 mRNA expression was significantly lower (3-fold) than in healthy controls, while FOXP3 protein expression determined by flow cytometry was not lower than in controls. IL-17 levels were 8-fold higher in KS than in controls (mean 340 vs 40 pg/mL)

Conclusion

Compared to healthy controls, in our patients, FOXP3 gene 543 SNP does not differ, FOXP3 mRNA expression was lower, without a correspondent lower protein expression, and IL-17 levels were much higher in patients. Due to the small number of patients, these results warrant further studies to evaluate FOXP3 expression in relationship with IL-17 in KS.