Transforming growth factor-β1 promotes Treg commitment in nasal polyposis after intranasal steroid treatment.

BACKGROUND: A predominant Th17 population and impaired Treg function is the marker of nasal polyposis (NP) in Chinese patients. TGF-β1, a multifunction cytokine, is a vital factor involved in inducing or restricting specific Th cell development. However, its role in NP has still not been well understood.

METHODS: In a double-blind trial, 30 subjects were randomized into 2 groups (15 steroid-treated NP, 15 untreated NP), and 15 normal subjects were allocated as control group. We analyzed the expression of TGF-β1, p-Smad2, p-STAT3, Smad7, SOCS3, IL-10, IL-17A, Foxp3, and RORc in the NP tissue of Chinese patients using mRNA and protein detection methods.

RESULTS: TGF-β1, p-Smad2, IL-10, SOCS3, and Foxp3 expression was higher in steroid-treated NP patients than in untreated NP patients. Conversely, expression of p-STAT3, Smad7, IL-17A, and RORc was higher in untreated NP patients than in steroid-treated NP patients, demonstrating that TGF-β1 was more likely to contribute to Treg commitment in Chinese NP patients after intranasal steroid treatment.

CONCLUSIONS: TGF-β1 may be a signature Treg cytokine, which is valuable for obtaining a clear understanding of the pathogenesis of NP. Moreover, intranasal steroid treatment attenuated the chronic inflammatory response in these patients by promoting Smad-dependent Treg functions and reducing STAT3-mediated Th17 reactions.