The expression of aquaporin-1,5 in the submandibular glands of mice with SjOgren's syndrome

PURPOSE: To investigate the distribution and abnormal expression of water channel proteins(AQP1 and AQP5) in the submandibular glands of mice with SjOgren's syndrome. METHODS: A total of 10 BALB/c mice underwent injection of homologous antigen of submandibular gland tissues mixed with complete freund's adjuvant(CFA), pertussis vaccine was added to enhance the immunological reaction. Another 10 mice underwent injection of same volume of normal saline as control; 6 weeks later,the submandibular glands were examined histologically by HE staining. The sections were labeled with antibody by immunohistochemical method and Western blot analysis. Computer-assisted image analysis system was performed to evaluate AQP1 and AQP5 distribution quantitatively in the immunoreactive acini and duct of both the experimental and the control group. RESULTS: In the control group, constant and clear reaction was observed with the first antibody concentration of 1∶200 for AQP5 and 1∶100 for AQP1. AQP1 in the acinic cell basement membrane, blood capillary and ductal basement membrane; AQP5 was strongly labeled in the acinic apical membrane and basolateral membrane,and in the secretary ducts,too;In the experimental group, Western blot found a 28kD(AQP1) and 27kD(AQP5) band in accordance with the expected molecular weight of AQP1 and AQP5, and quantitative analysis of Western blot showed that the expression of AQP1 and AQP5 in the experimental group had a significant decline compared with the control group(P0.01); the immunoreactivity was predominantly localized to the acinic basal membrane and ductal cells. CONCLUSION: The abnormal distribution of AQP1 and AQP5 in the acini and ducts of the salivary gland is likely to contribute to the deficiency of fluid secretion, which is a defining feature of SS patients. The sharp decrease of AQP1 and AQP5 expressed in SS patients may play an important role in leading to dry mouth.