The STAT6 inhibitor AS1517499 reduces the risk of asthma in mice with 2,4-dinitrochlorobenzene-induced atopic dermatitis by blocking the STAT6 signaling pathway

Abstract

Background: Epidemiological studies have revealed a link between atopic dermatitis (AD) and asthma. AS1517499, a selective signal transducer and activation of transcription 6 (STAT6) inhibitor, has been shown to effectively block this connection. In this study, we further explored the underlying mechanism by constructing an AD mouse model.

Methods: Female BALB/c mice were randomly divided into four groups (n = 10/group). The AD mouse model was established by 2,4-dinitrochlorobenzene induction with repeated ovalbumin challenge. AS1517499 and corn oil were used as treatment interventions. The features of airway inflammation, remodeling, and hyperactivity were analyzed.

Results: Active use of AS1517499 in AD mice effectively reduced Th2-related cytokine levels, alleviated airway eosinophil and lymphocyte infiltration, and regulated GATA3/Foxp3 levels and subepithelial collagen deposition. These changes might be due to specific blockade of the STAT6 signaling pathway.

Conclusion: AS1517499 could partially block the association between AD and asthma by specifically inhibiting the STAT6 signaling pathway.

Keywords: AS1517499; Asthma; Atopic dermatitis; STAT6; Th2 cells; Treg cells.

Fig. 1

Experimental timeline of mouse model establishment and intervention. Forty female BALB/c mice were randomly divided into four groups (n = 10/group). The abdomens and backs of the mice were exposed to 20 μL of 7% 2,4-dinitrochlorobenzene (DNCB) for 2 consecutive days, and the back skin was additionally challenged with 40 μL of 1% DNCB and 40 μL of ovalbumin (OVA)-PBS solution every 3 days, for a total of four rounds. The control group was treated in the same manner with acetone solution. On day 21, the mice were challenged via inhalation of aerosolized 1% OVA solution for 30 min every day for 7 consecutive days. Intraperitoneal injection of AS1517499 (10 mg/kg; dissolved in corn oil) and corn oil were administered to the AD and control groups, respectively, 1 h before aerosol inhalation (days 21, 23, 25, and 27). On day 30, the mice were sacrificed, and the required samples were collected

Fig. 2

Effects of AS1517499 on the severity of skin and histopathological characteristics of 2,4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis (AD) in BALB/c mice. Representative images acquired after treatment (upper panel), and AD-like histopathological changes revealed by H&E staining under a light microscope (20 × magnification) in mouse skin samples (below panel). The images are representatives of the following four groups (n = 10 per group): A\E vehicle control (VC), B\F AD, C\G corn oil treatment (COTR), and D\H AS1517499 treatment (AS) groups

Fig. 3

Measurement of airway hyperresponsiveness in acetylcholine (ACH)-challenged mice. The Penh values of the four groups were measured. The results are expressed as the mean ± SD. Vehicle control (VC), atopic dermatitis (AD), corn oil treatment (COTR), and AS1517499 treatment (AS) groups (n = 10 per group). *P < 0.05

Fig. 4

Cellular profile of bronchoalveolar lavage fluid. Leukocyte classification counting with Wright-Giemsa staining: A Total leukocyte count (Leu), B neutrophil (Neu), C lymphocyte (Lym), D monocyte (Mon), and E eosinophil (Eos) counts. The results are expressed as the mean ± SD (n = 10 per group). *P < 0.05

Fig. 5

Histopathological analysis of airway structure and collagen distribution. Images of pathological sections of the lung tissues following H&E staining (upper panel) and Masson staining (lower panel) when observed under electron microscopy (100 × magnification). VC, vehicle control; COTR, corn oil treatment; AS, AS1517499 treatment (n = 10 per group)

Fig. 6

Serum levels of IL-10 and IL-33. ELISA results of A IL-10 and B IL-33 levels in the serum. The results are expressed as the mean ± SD (n = 10 per group). *P < 0.05

Fig. 7

Expression of GATA3, Foxp3, and STAT-6 in lung tissues. The right lung tissue was obtained from the four groups of mice and analyzed using RT-qPCR and western blotting. A Protein expression analysis of Foxp3, GATA3, and STAT6 in mouse lung tissues; B Image J quantitative analysis of the western blot results. C Quantitative mRNA expression of Foxp3, GATA3, and STAT6. The levels of FOXP3, GATA3, and STAT6 were measured relative to those of GAPDH. All data are expressed as the mean ± SD (n = 10 per group). *P < 0.05