[Study the involvement of Langerin in mediating epicutaneous sensitization of atopic dermatitis-like mouse model]

Objective: To explore the role of Langerin in mediating epicutaneous sensitization of atopic dermatitis (AD) in mouse model. Methods: Mice were topically treated with calcipotriol (MC903) plus ovalbumin (OVA) on the ears to establish AD mouse models, and mice were divided into wild-type control group, wild-type AD group, Langerin knockout control group, and Langerin knockout AD group. Changes of lesion were daily observed. Infiltration of inflammatory cells, mRNA expression of Tslp, Il4, Il13, Il17a, and Il22, levels of serum total IgE, OVA-specific IgE (sIgE), OVA sIgG1 and OVA sIgG2a, proportion of regulatory T (Treg) cells in cervical draining lymph nodes were evaluated at the end of model preparation. Results: Skin tumidness and thickness, dermal inflammatory cells infiltration, the mRNA expression levels of Tslp, Il4, Il13, Il17a and Il22 in wild-type AD groups were higher than those in wild-type control groups, with (1.80±0.66, 1.64±0.25, 1.71±0.54, 2.41±0.23, 2.49±0.32) and (0.53±0.45, 0.85±0.29, 0.73±0.50, 0.72±0.25, 0.56±0.29), respectively (all P<0.05). In addition, the levels of serum total IgE, OVA sIgE and OVA sIgG1 in wild-type AD groups were higher than those in wild-type control groups, with [(1 216.00±572.70) ng/ml, (597.00±538.30) ng/ml, 1.59±0.09] and [(24.22±35.04) ng/ml, (20.01±41.71) ng/ml, 1.16±0.03], respectively (all P<0.05). In Langerin knockout mice, compared to wild-type mice, skin erythema, skin tumidness, epidermal thickening, inflammatory cell infiltration were more obvious; the mRNA expression levels of Tslp, Il4, Il13, Il17a and Il22 were upregulated with (8.19±6.44, 2.53±0.69, 2.82±0.73, 3.94±1.32, 3.80±1.43) (all P<0.05); the levels of serum total IgE, OVA sIgE and OVA sIgG1 were significantly increased with (2 508.00±657.10) ng/ml, (1 808.00±470.70) ng/ml, (1.73±0.09) (all P<0.05); the number of CD4⁺CD25⁺CD127^-Treg cells were decreased significantly with (13.25±0.96)% and (15.31±1.47)%, respectively (P<0.05). Conclusion: Langerin is involved in mediating epicutaneous sensitization of the AD mouse model and plays a negative immunoregulatory role.