Abstract:

Objective To establish an oxidative stress mouse model of atopic dermatitis (AD) by applying 2,4-dinitrofluorobenzene (DNFB) to the back and post-auricular skin of KM mice, and to evaluate the regulatory role of the RAGE-NLRP3 axis (receptor for advanced glycation end products-NOD-like receptor family, pyrin domain containing 3 axis) in AD-related oxidative stress, thereby providing a potential therapeutic target for AD treatment. Methods Twenty SPF-grade female KM mice were randomly divided into a control group (Control group) and an experimental group (DNFB group), with 10 mice in each group. Mice in the Control group were treated with an acetone-olive oil vehicle (acetone: olive oil = 3:1) on their back and post-auricular skin. Mice in the DNFB group were treated with 0.5% DNFB (prepared by adding 0.5 g DNFB per 100 mL of acetone-olive oil vehicle) on the same areas, once daily for 14 consecutive days. The severity of skin lesions was scored on days 2, 4, 6, 9, 12, and 14 of treatment. On day 14, scratching behavior and ear thickness were evaluated. Ear swelling was evaluated on the final day by measuring bilateral ear thickness three times with a vernier caliper; the three measurements were averaged. HE staining was used to observe morphological and structural changes of cells in the back skin tissues. The mRNA and protein expression levels of RAGE (receptor for advanced glycation end products) in skin tissues were detected by quantitative real-time PCR, Western blot, and immunohistochemical staining. The mRNA expression levels of oxidative stress-related molecules, including NLRP3 (NOD-like receptor family, pyrin domain containing 3), caspase-1 (cysteine-dependent aspartate-specific protease 1), and IL-1β (Interleukin-1β), were detected by quantitative real-time PCR. Results On day 14, the back skin lesion scores of the Control group and DNFB group were (0.20±0.42) and (9.93±1.30) (P<0.000 1), respectively. Scratching behavior scores were (5.00±2.05) and (49.26±8.49) episodes, respectively (P<0.000 1), and ear thicknesses were (213.00±11.87) μm and (765.93±140.47) μm (P<0.000 1), respectively. The DNFB group exhibited marked skin dryness, desquamation, and thickening. HE staining results showed that skin inflammation was obvious in the DNFB group, consistent with the pathological features of AD. Quantitative real-time PCR and Western blot results showed that compared with the Control group, the mRNA expression level of RAGE in skin tissues of the DNFB group was significantly increased (P<0.05), and the protein expression level of RAGE was also significantly increased (P<0.01). Immunohistochemical staining results showed that compared with the Control group, skin tissue sections of the DNFB group exhibited thickened stratum corneum and fibrotic proliferation of fibroblasts in the interstitium under microscopic observation, with a significant increase in RAGE protein expression in the skin tissues (P<0.01). Quantitative real-time PCR results showed that the mRNA expression levels of NLRP3, caspase-1, and IL-1β in skin tissues of the DNFB group were all significantly increased (P<0.01). Conclusion The AD mouse oxidative stress model has been successfully established by topical DNFB application. RAGE may promote the development of AD by regulating the NLRP3 inflammasome and IL-1β release, forming an oxidative-inflammatory cascade, suggesting that it could be a potential therapeutic target for AD.

Key words: 2,4-dinitrofluorobenzene, Atopic dermatitis, Inflammatory response, Oxidative stress, KM mice