局部注射环孢素A对非肥胖糖尿病小鼠下颌下腺分泌功能及炎症的影响

目的: 探讨非肥胖糖尿病(non-obese diabetic, NOD)小鼠下颌下腺局部注射环孢素A(cyclosporine A, CsA)对腺体唾液分泌功能及炎症的影响。方法: 选用21只14周龄和18只21周龄雌性NOD小鼠,随机平均分为低剂量组、高剂量组和对照组。NOD小鼠下颌下腺局部注射CsA 1周后,检测刺激性唾液流率;取下颌下腺标本,制作石蜡切片,用苏木精-伊红(hematoxylin-eosin staining, HE)染色,显微镜下观察腺体淋巴细胞浸润程度;用徕卡图像分析系统计数淋巴细胞浸润灶的数量,计算灶性指数和淋巴细胞浸润灶的面积比;用实时荧光定量聚合酶链式反应(quantitative real-time polymerase chain reaction, qRT-PCR)检测下颌下腺中肿瘤坏死因子-α(tumor necrosis factor-α, TNF-α)、干扰素-γ(interferon-γ, IFN-γ)、白介素-4(interleukin-4, IL-4)、IL-13、IL-17F、IL22和IL-23a等炎症细胞因子的表达;用脱氧核糖核苷酸末端转移酶介导的缺口末端标记法(terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling, TUNEL)检测下颌下腺凋亡细胞;用全自动生化分析仪测量血清肌酐(serum creatinine,Scr)、尿素氮(blood urea nitrogen, BUN)、尿酸(uric acid, UA)、丙 氨 酸 氨 基 转 移 酶(alanine aminotransferase,ALT)、天冬氨酸氨基转移酶(aspartate aminotransferase,AST)、碱性磷酸酶(alkaline phosphatase, ALP)、白蛋白(albumin, ALB)和γ-谷氨酰基转移酶(γ-glutamyl transferase,GGT), 评估肝肾功能。结果: 下颌下腺局部注射CsA后,14周龄和21周龄NOD小鼠的刺激性唾液流率较同龄对照组明显增加(P<0.01或P<0.05);14周龄低剂量组NOD小鼠下颌下腺淋巴细胞浸润灶的灶性指数和面积比较同龄对照组显著减少(P<0.01);低剂量和高剂量组减轻炎症反应和改善唾液分泌功能的作用相似;下颌下腺整体炎症细胞因子表达水平无明显降低;低剂量和高剂量组下颌下腺凋亡细胞数和对照组相比有减少趋势,但差异无统计学意义;局部注射CsA对NOD小鼠肝肾功能无影响。结论: 局部应用CsA可减轻NOD小鼠的下颌下腺淋巴细胞浸润,并改善唾液分泌功能。     

激活毒蕈碱乙酰胆碱受体调控下颌下腺分泌的机制研究

SUMMARY Muscarinic acetylcholine receptors (mAChRs), including M1-M5 subtypes, are classic receptors in regulating water, ion, and solute transport in salivary gland. Our work focuses on the studies on the expression pattern and function of mAChR in the submandibular gland (SMG), and the under-lying mechanism involved in the mAChR-regulated secretion, together with the effect of parasympathectomy on the salivary secretion. Microvascular autotransplantation of SMG into the temporal fossa provides a continuous and endogenous source of fluids, and is currently an effective method for treating severe keratoconjunctivitis sicca. By using RT-PCR, Western blotting, and immunofluorescence, our data demonstrated that the expression of M1 and M3 subtypes were decreased in latent period in rabbit SMG autotransplantation model, whereas carbachol stimulation promoted the salivary secretion, as well as M1 and M3 expressions. By contrast, mAChRs were hypersensitive in epiphora SMGs, whereas atropine gel and botulinum toxin A application significantly inhibited the hypersecretion in both animal models and patients. Furthermore, the possible intracellular signal molecules involved in the mAChR-modulated saliva-ry secretion were explored. Activation of mAChR upregulated the expression of aquaporin 5 (AQP5), the main transporter that mediated water secretion through transcellular pathway, and led to AQP5 trafficking from lipid rafts to non-lipid microdomain. Extracellular signal-regulated kinase 1/2 (ERK1/2) was involved in the mAChR-regulated AQP5 content. mAChR activation also modulated the expression, distribution, and function of tight junction proteins, and increased paracellular permeability. ERK1/2/β-arrestin2/clathrin/ubiquitin signaling pathway was responsible for the mAChR-regulated downregulation of tight junction molecule claudin-4. Cytoskeleton filamentous actin (F-actin) was also involved in the distribution and barrier function of epithelial tight junctions. Besides, endothelial tight junctions were opened by mAChR agonist-evoked salivation in the mice. Furthermore, parasympathetic denervation increased resting salivary secretion in the long terminrats and minipigs. Taken together, our work demonstrated that mAChR regulated saliva secretion via transcellular and paracellular pathways in SMG epithe-lium as well as tight junction opening in SMG endothelium. Modulation of mAChR might be a promising strategy to ameliorate SMG dysfunction.