Effects of a fusion protein LTβR-Fc on ovalbumin-induced dermatitis in a mouse model

Abstract

Objective To evaluate effects of a fusion protein LTβR-Fc, which can block the herpesvirus entry mediator ligand (LIGHT-HVEM) signaling pathway, on ovalbumin-induced dermatitis in a mouse model. Methods Thirty BALB/c mice were randomly and equally divided into 3 groups: blank control group treated with 100 μl of sodium chloride physiological solution, model group sensitized with 100 μl of sodium chloride physiological solution containing 100 μg ovalbumin, blocker group firstly blocked with 100 μl of sodium chloride physiological solution containing 100 μg LTβR-Fc followed by sensitization with 100 μl of sodium chloride physiological solution containing 100 μg ovalbumin at 24 hours after the blocking. Disease severity was evaluated by eczema area and severity index (EASI) score, and lesional size was measured on day 0, 4, 8, 12, 15, 20, 23, 27, 31 and 34 after the first sensitization. A total of three sessions of sensitization were carried out. At the end of treatment, all the mice were sacrificed after serum was obtained from their orbital cavities. Thereafter, tissue specimens were obtained from skin lesions, and single cell suspensions of the spleen were prepared. RT-PCR was performed to detect mRNA expressions of interferon γ (IFN-γ) , interleukin 4 (IL-4) and IL-5 in murine lesions, ELISA to measure IFN-γ, IL-4 and IL-5 levels in culture supernatants of murine splenocytes, as well as ovalbumin-specific and total IgE and IgG1 levels in murine sera. Results LTβR-Fc significantly suppressed inflammatory response in the mouse model of dermatitis induced by ovalbumin. Compared with the model group, the blocker group showed significantly decreased lesion area and EASI score (both P<0.05). In addition, a significant decrease was observed in the mRNA expressions of IL-4 (0.88 ± 0.25 vs. 1.81 ± 0.25, P<0.05) , IL-5 (0.75 ± 0.15 vs.1.24 ± 0.26, P<0.05) and IFN-γ (0.62 ± 0.09 vs. 1.11 ± 0.19, P<0.05) in murine lesions, and in supernatant levels of IL-4 (9.58 ± 1.44 ng/L vs. 20.12 ± 5.39 ng/L, P<0.05) , IL-5 (11.37 ± 2.02 ng/L vs. 22.77 ± 4.07 ng/L, P<0.05) and IFN-γ (16 167 ± 950.40 ng/L vs. 23 930 ± 44.20 ng/L, P<0.05) in the blocker group compared with the model group. The serum levels of both total IgE and ovalbumin-specific IgE were significantly lower in the blocker group than in the model group (total IgE: 27 466.67 ± 2 052.64 μg/L vs. 32 277 ± 407.53 μg/L, P<0.05; ovalbumin-specific IgE: 1 296.33 ± 32.72 μg/L vs. 2 323.33 ± 502.43 μg/L, P<0.05) , so were those of total IgG1 (0.46 ± 0.11 μg/L vs. 0.84 ± 0.11 μg/L, P<0.05) and ovalbumin-specific IgG1 (0.62 ± 0.11 μg/L vs. 0.86 ± 0.07 μg/L, P<0.05). Conclusion The fusion protein LTβR-Fc can alleviate symptoms of ovalbumin-induced dermatitis in the mouse model likely by suppressing the LIGHT-HVEM signaling pathway, suggesting that this signaling pathway may serve as a target for the treatment of dermatitis (such as atopic dermatitis). Key words: Dermatitis, atopic; Models, animal; Ovalbumin; T-lymphocytes, helper-inducer; Interleukins; Interferon-gamma; LIGHT-HVEM