关键词: 上呼吸道黏膜, 寒冷刺激, 环磷酰胺, 黏膜免疫功能低下, 分泌型免疫球蛋白A

Abstract: Objective　To establish animal models of impaired upper respiratory tract mucosal immune function induced by different methods, providing experimental evidence for the study of disease mechanisms and prevention strategies.Methods　Fifty male BALB/c mice were randomly divided into 10 groups, control groups (A0, B0) and model group 1 (A1, B1), model group 2 (A2, B2), model group 3 (A3, B3), and model group 4 (A4, B4), with five mice in each group. Except for the control groups, all other groups underwent modeling, with group A receiving continuous modeling for 7 d and group B for 14 d. The specific modeling method were as follows: model group 1 (-20 ℃), model group 2 (4 ℃), model group 3 (-20 ℃ + cyclophosphamide), and model group 4 (4 ℃ + cyclophosphamide). After continuous modeling for 7 d and 14 d, changes in mouse behavior, body weight, and immune organ (thymus, spleen) indices were observed. Hematoxylin-eosin (HE) staining was used to examine pathological changes in the upper respiratory tract mucosa (nose, oral cavity, throat). Enzyme-linked immunosorbent assay (ELISA) was employed to measure immune factor levels in saliva and serum. Immunofluorescence was used to localize polymeric immunoglobulin receptor (PIgR) and secretory component (SC) proteins.Results　After 7 d of modeling, compared with control group A0, mice in model groups A1, A3, and A4 showed reduced spontaneous activity, poor mental state, and significant decreases in body weight, thymus index, and spleen index (P<0.05). Hemorrhage, edema, and inflammatory cell infiltration were observed in the upper respiratory tract mucosa. Model group A2 showed a significantly decreased thymus index (P<0.05), but no significant difference in spleen index. The detection results of immune factors in saliva and serum showed that the levels of lysozyme (LZM), secretory immunoglobulin A (sIgA), and immunoglobulin A (IgA) in the saliva of groups A1, A3, and A4 were significantly decreased (P<0.05). In serum, LZM and IgA were significantly decreased in group A1 (P<0.05), while sIgA showed no significant difference. Serum LZM, sIgA, and IgA were all significantly decreased in group A3 (P<0.05). Serum LZM and IgA were significantly decreased in group A4 (P<0.05), while sIgA showed no significant difference. In model group A2, only the salivary sIgA content was significantly decreased (P<0.05), and there were no significant differences in other indicators compared with the control group A0. After 14 d of modeling, compared with the control group B0, mice in model groups B1, B2, B3, and B4 all showed reduced spontaneous activity, listlessness, significantly decreased body mass, thymus index, and spleen index (P<0. 05), and persistent pathological changes in the upper respiratory mucosa. The detection results of immune factors showed that salivary and serum levels of LZM, sIgA, and IgA in groups B1, B3, and B4 were significantly lower than those in the control group (P<0.05). In group B2, salivary LZM, sIgA, and IgA were significantly decreased (P<0.05), and serum LZM and sIgA were significantly decreased (P<0.05), while serum IgA showed no significant difference.Conclusion　Exposure to -20 ℃ environmental stimulation for 20 min, twice daily, for 7 consecutive days can induce impaired upper respiratory tract mucosal immunity in mice. In contrast, crating a corresponding model under 4 ℃ conditions requires either combined treatment with cyclophosphamide or extended modeling duration.

Key words: upper respiratory tract mucosa, cold-stress, cyclophosphamide, low mucosal immunity, secretory immunoglobulin A