Ubiquitin‑specific peptidase 25 (USP25) is a key deubiquitylase belonging to the USP superfamily that is primarily involved in inflammation and the immune response. Thymic stromal lymphopoietin (TSLP) is an epithelial‑derived cytokine that is regarded as the master switch that initiates and maintains the type 2 immune response in allergic rhinitis (AR). However, the molecular mechanisms by which USP25 regulates TSLP signaling in the nasal epithelium in AR remain unclear. The present study assessed the protein expression levels of USP25 in the nasal epithelium of patients with AR. Moreover, USP25 knockout (KO) and wild‑type (WT) mice were treated with ovalbumin (OVA) to establish a model of AR. The results of western blotting and immunohistochemistry in the present study demonstrated that the protein expression levels of USP25 were significantly decreased in the nasal mucosa of patients with AR and AR mice, whereas the protein expression levels of TSLP were significantly increased. Allergic inflammation was more severe in USP25 KO mice compared with WT mice exposed to OVA, as demonstrated by increased nose scratching and sneezing, increased eosinophil infiltration, goblet cell hyperplasia and enhanced T helper type 2 (Th2) cytokine production. The results of in vitro experiments demonstrated that silencing or overexpression of USP25 decreased or increased TNF receptor‑associated factor 3 (TRAF3) protein expression levels, respectively, in human nasal epithelial cells, whereas TSLP protein expression levels were negatively associated with the expression of USP25 and TRAF3. In summary, USP25 downregulation enhanced TSLP signaling in the nasal mucosal epithelium via decreased TRAF3 expression, thereby exacerbating inflammation in AR. Therefore, USP25 may act as a novel therapeutic target in AR.
Keywords: allergic rhinitis; deubiquitylase; epithelial‑derived cytokine; thymic stromal lymphopoietin; ubiquitin‑specific peptidase 25.