金黄色葡萄球菌肠毒素B在变应性鼻炎发病机制中作用的实验研究

发布时间：2018-09-14 07:29

【摘要】：目的: 变应性鼻炎(AR)是常见的耳鼻咽喉科疾病,也是常见的呼吸道变应性疾病。变应性鼻炎在全球范围内的患病率为10-25%,而在我国西部的部分地区其患病率高达34.31%,是严重危害人类健康和生活质量的常见疾病。以变应性鼻炎为代表的变应性疾病的发病机制研究一直都是国内外专家关注的热点。一般经典的认识是,变应原桥联IgE,介导肥大细胞脱颗粒释放炎性介质,引起不同程度的鼻黏膜炎症,即Ⅰ型超敏反应是变应性鼻炎发病的主要机制。但临床上发现,血清中特异性IgE水平与症状严重程度并非完全相关,可能存在非经典途径。近年来,细菌超抗原学说越来越得到广大学者的重视。现有研究证实,细菌超抗原影响免疫调节细胞(T淋巴细胞)和促炎细胞(树突状细胞、嗜酸性粒细胞、上皮细胞等)的活性,诱导或促进变态反应性疾病的发生和发展。金黄色葡萄球菌肠毒素B(SEB)是由金黄色葡萄球菌产生的一种超抗原,能直接连接抗原提呈细胞的MHC II类分子外侧和T细胞受体Vβ区,同时非特异性激活体内将近30%的T细胞,而普通抗原仅能激活0.01%的T细胞。通过SEB超抗原的这种槽外连接,有利于被MHC呈递的抗原肽更有效的与T细胞可变区结合,增强了变应原的抗原性,促进变态反应性炎症的发生、发展。另外,SEB可以作为变应原活化特异性T细胞,继而诱导抗原特异性IgE产生,发生经典的变态反应。金黄色葡萄球菌及其分泌的超抗原广泛分布人类的皮肤和鼻腔,人们在日常生活中接触金葡菌超抗原的频率极高,这就增加了特应性个体罹患变态反应性疾病的风险。但尚无确切证据说明SEB可作为变应原诱导变应性鼻炎的发生。本研究应用SEB反复鼻腔喷滴,观察豚鼠打喷嚏、抓鼻等变应性鼻炎典型症状,鼻黏膜中嗜酸性粒细胞的浸润情况,及血清SEB特异性IgE和IgG1的表达,从而证明SEB作为变应原,能够诱导变应性鼻炎的发生。方法: 将20只健康Hartley系豚鼠随机分为2组:模型组和对照组,每组10只。模型组鼻腔喷滴SEB,每天1次,连续14天。每次喷滴前,用4%利多卡因(每侧鼻孔20μl)先喷滴鼻腔,以抑制鼻腔纤毛运动,延长变应原在鼻腔停留时间。间隔7天后,以同样剂量SEB喷滴鼻腔激发,每周激发2次,连续激发3周。激发前,不再鼻腔应用利多卡因。对照组以生理盐水代替SEB进行实验。在激发阶段,对其喷嚏和抓鼻做动态症状学观察;间接ELISA法检测血清SEB特异性IgE、IgG1和IgG2水平;HE染色观察鼻腔组织的病理改变。结果: ⑴模型组豚鼠出现典型的变应性鼻炎症状,如频繁喷嚏和抓鼻;模型组豚鼠血清SEB特异性IgE和IgG1滴度明显升高;模型组豚鼠的鼻腔黏膜出现以嗜酸性粒细胞为主的炎症细胞浸润,黏膜下间质明显水肿,小血管扩张。 ⑵对照组豚鼠未出现变应性鼻炎的典型症状,血清中无可检测水平的SEB特异性IgE和IgG1,鼻黏膜未见明显改变。 ⑶与对照组比较,模型组豚鼠鼻黏膜相关淋巴组织中IL-23 mRNA表达下调,鼻腔灌洗液中IL-17水平降低。结论: ⑴采用反复鼻腔喷滴SEB的方法诱导出鼻腔黏膜变应性炎症,验证了SEB可以作为传统的变应原诱导变应性鼻炎的发生。 ⑵采用反复鼻腔喷滴SEB致敏,鼻腔连续激发的方法诱导出鼻腔变应性炎症,从而成功地建立了具有双相反应的变应性鼻炎动物模型,为进一步研究伴有金葡菌鼻腔携带的变应性鼻炎的发病机制和迟发相反应奠定了基础。 ⑶模型组豚鼠Th17型细胞因子IL-23、IL-17的表达降低,而Th2细胞因子IL-4的表达升高,提示变应性鼻炎存在Th2/Th17细胞因子网络失衡,这可能在变应性鼻炎的发病中起着关键的作用。
[Abstract]:Objective:
Allergic rhinitis (AR) is a common ear-nose-throat disease and a common respiratory allergic disease. The prevalence of allergic rhinitis is 10-25% in the world, while it is 34.31% in the western part of China. It is a common disease that seriously endangers human health and quality of life. The pathogenesis of allergic diseases has always been the focus of attention of experts at home and abroad.The classical understanding is that allergen bridging IgE mediates mast cell degranulation to release inflammatory mediators and induces varying degrees of nasal mucosal inflammation, i.e. type I hypersensitivity is the main pathogenesis of allergic rhinitis.But clinically, it is found that serum is specific. In recent years, the theory of bacterial superantigens has attracted more and more attention of scholars. It has been confirmed that bacterial superantigens affect the activity of immunoregulatory cells (T lymphocytes) and inflammatory cells (dendritic cells, eosinophils, epithelial cells, etc.). Inducing or promoting the occurrence and development of allergic diseases.
Staphylococcal enterotoxin B (SEB) is a superantigen produced by Staphylococcus aureus. It can directly connect the MHC class II molecule of antigen-presenting cells with the V beta region of T cell receptor. At the same time, it can nonspecifically activate nearly 30% of T cells in vivo, while common antigen can only activate 0.01% of T cells. In addition, SEB can be used as an allergen to activate specific T cells, and then induce the production of antigen-specific IgE, resulting in classical allergic reactions. Staphylococcus aureus and its components. The secreted superantigens are widely distributed in human skin and nasal cavity, and people are exposed to Staphylococcus aureus superantigens very frequently in daily life, which increases the risk of allergic diseases in atopic individuals.
The typical symptoms of allergic rhinitis, such as sneezing and scratching nose, the infiltration of eosinophils in nasal mucosa, and the expression of SEB-specific IgE and IgG1 in serum were observed by repeated nasal drops of SEB, which proved that SEB as an allergen could induce the occurrence of allergic rhinitis in guinea pigs.
Method:
20 healthy Hartley guinea pigs were randomly divided into two groups: model group and control group, 10 in each group. The model group was given SEB once a day for 14 consecutive days. Lidocaine was not used in nasal cavity before stimulation. The control group was treated with normal saline instead of SEB. The sneezing and scratching noses were observed by dynamic symptoms during stimulation. The serum levels of SEB-specific IgE, IgG1 and IgG2 were detected by indirect ELISA, and the pathological changes of nasal tissues were observed by HE staining. Change.
Result:
_The model group showed typical allergic rhinitis symptoms, such as frequent sneezing and scratching nose; the serum SEB-specific IgE and IgG1 titers of the model group increased significantly; the nasal mucosa of the model group showed eosinophil-based inflammatory cell infiltration, submucosal interstitial edema, and small vessel dilatation.
_There were no typical symptoms of allergic rhinitis in the control group, no detectable levels of SEB-specific IgE and IgG1 in serum, and no significant changes in nasal mucosa.
_Compared with the control group, the expression of IL-23 mRNA in the nasal mucosa-associated lymphoid tissue was down-regulated and the level of IL-17 in nasal lavage fluid was down-regulated in the model group.
Conclusion:
_Allergic inflammation of nasal mucosa was induced by repeated nasal Dropping of SEB, which proved that SEB could be used as a traditional allergen to induce allergic rhinitis.
_The allergic rhinitis animal model with biphasic reaction was successfully established by repeated nasal instillation of SEB and nasal continuous stimulation, which laid a foundation for further study on the pathogenesis and delayed phase reaction of allergic rhinitis with Staphylococcus aureus.
_In the model group, the expression of Th17 cytokines IL-23 and IL-17 was decreased, while the expression of Th2 cytokines IL-4 was increased, suggesting that there was an imbalance of Th2/Th17 cytokine network in allergic rhinitis, which may play a key role in the pathogenesis of allergic rhinitis.
【学位授予单位】：重庆医科大学
【学位级别】：博士
【学位授予年份】：2011
【分类号】：R765.21

【共引文献】