Abnormal distribution of aquaporin-5 in salivary glands in the NOD mouse model for Sjögren's syndrome.

OBJECTIVE: To localize aquaporin-5 in healthy salivary gland acinar cells and to check if it is abnormally translocated in an experimental NOD mouse model for Sjogren9s syndrome (SS). METHODS: Healthy BALB/c control mice and autoimmune focal adenitis NOD mice were studied. Aquaporin-5 was stained using avidin-biotin-peroxidase complex and indirect immunofluorescence staining methods, and visualized using light and laser scanning confocal microscopy. RESULTS: Aquaporin-5 was found in the apical domain of the acinar cell plasma membrane in healthy BALB/c mice. In contrast, aquaporin-5 was found in the apical and basolateral acinar plasma cell membrane in parotid, submandibular, and sublingual glands in NOD mice. This was confirmed using laser scanning confocal microscopy for optical sectioning and image reconstruction. CONCLUSION: Our findings reveal an abnormal translocation of aquaporin-5 in an experimental SS animal model and support observations that implied a similar loss of the ordered and polarized expression of aquaporin-5 in human SS labial and lacrimal glands.