链球菌改进咪喹莫特诱导银屑病样皮炎动物模型的研究

Modification in imiquimod-induced psoriasis-like dermatitis animal model by Streptococcus

背景链球菌感染可诱发并加重银屑病。目前银屑病研究中运用最广的模型是咪喹莫特诱导的银屑病样皮炎动物模型,但皮损持续时间短、易消退的缺点影响了其应用价值。目的观察链球菌是否可改良咪喹莫特诱导建立的银屑病样皮炎动物模型。方法将C57BL/6小鼠随机分为链球菌组(GAS+IMQ)、咪喹莫特组(PBS+IMQ)及空白组(PBS+VAS),每组各15只。实验第1天,链球菌组小鼠鼻腔内滴加链球菌活菌液,空白组和咪喹莫特组小鼠鼻腔内滴加等量PBS溶液。实验第3天,链球菌组和咪喹莫特组小鼠背部皮肤涂抹咪喹莫特乳膏,空白组小鼠背部皮肤涂抹医用黄凡士林,三组小鼠连续涂抹并观察21 d。实验第3天后每天对皮损进行拍照及银屑病皮损面积及严重程度指数(psoriasis area and severity index,PASI)评分。实验第0、3、10、17、24天,每组随机处死3只小鼠,收集皮肤组织进行组织病理学检查,免疫组织化学法检测皮损中Ki-67表达情况,实验第24天酶联免疫吸实验(ELISA)法检测各组小鼠血清中白细胞介素(interleukin,IL)-17、IL-6及肿瘤坏死因子α(tumor necrosis factor-α,TNF-α)的含量。结果实验第3天后链球菌组及咪喹莫特组小鼠均出现银屑病样皮损,PASI评分于第10天达到顶峰。之后咪喹莫特组小鼠皮损严重程度逐渐下降,实验第24天皮损基本消退。链球菌组皮损严重程度同期均高于咪喹莫特组(P<0.05),实验第24天链球菌组小鼠皮肤鳞屑性红斑皮损持续存在。皮肤组织病理:链球菌组和咪喹莫特组小鼠均出现Munro微脓肿、棘层肥厚及真皮层炎症细胞浸润,同期相比链球菌组小鼠表皮厚度均高于咪喹莫特组小鼠(P<0.05),链球菌组小鼠皮损中Ki-67阳性表达显著强于咪喹莫特组(P<0.05)。与空白组和咪喹莫特组相比,链球菌组小鼠血清中IL-17、IL-6、TNF-α含量均升高(P<0.05)。结论链球菌可使咪喹莫特诱导的银屑病样皮炎动物模型皮损维持时间延长且更典型,可能是一种有效可行的改良动物模型。

Background Streptococcus infection can induce and aggravate psoriasis.Imiquimod-induced psoriasis-like dermatitis animal model is the most widely used model at present.However,its application value is hampered by its short duration and regression.Objective To observe whether Streptococcus can modify the imiquimod-induced psoriasis-like dermatitis animal model.Methods C57BL/6 mice were randomly divided into Streptococcus group(GAS+IMQ),IMQ group(PBS+IMQ)and control group(PBS+VAS),with 15 mice in each group.On the first day,Streptococcus bacteria solution was added into the nasal cavity of the Streptococcus group,and the same amount of PBS solution was added into the control group and IMQ group.Imiquimod cream was applied on the third day for modeling in the Streptococcus group,IMQ group,and vaseline cream for the control group.The continued observation was performed for another 21 days.From the third day,skin lesions were photographed daily,and the PASI score was performed.Three mice in each group were randomly sacrificed on day 0,3,10,17 and 24,then skin tissues of each group were collected for histopathological examination and the expression level of Ki-67 in skin tissue was detected by immunohistochemistry.The serum levels of IL-17,IL-6,and TNF-αon day 24 were determined by enzyme-linked immunosorbent assay(ELISA).Results Psoriasis-like dermatitis lesions were found in both the Streptococcus group and IMQ group after modeling,and PASI scores reached the peak on day 10.The severity of psoriasis-like dermatitis lesions in IMQ group gradually decreased and vanished on day 24,and it was severer in the mice of Streptococcus group than those in the IMQ group(P<0.05).The psoriasis-like dermatitis lesions of the Streptococcus group were maintained on day 24 in mice of Streptococcus group.Skin histopathology showed that munro microabscess,spinous layer hypertrophic,and dermal inflammatory cell infiltration were observed in both Streptococcus group and IMQ group.Compared with the IMQ group and the control group,the epidermal thickness of the Streptococcus group was higher(P<0.05),so did the positive expression of Ki-67 in skin lesions(P<0.05).Compared with the control group and the IMQ group,the serum levels of IL-17,IL-6,and TNF-αin the Streptococcus group increased(all P<0.05).Conclusion Streptococcus can prolong the maintenance time of the imiquimod-induced psoriasis-like dermatitis animal model,which is more typical and may be a feasible and effective modified animal model.