Severe alterations in expression and localisation of α6β4 integrin in salivary gland acini from patients with Sjögren syndrome

Objectives: In salivary glands from patients with Sjögren syndrome, overexpression of laminins 1 and 5 and disorganisation of the acinar basal lamina have been reported. Laminin 5 mediates association of the basal lamina with epithelial cells by forming adhesion complexes upon interaction with α6β4 integrin. In the present work, mRNA and protein levels of α6β4 integrin were determined and its localisation in salivary glands evaluated in patients with Sjögren syndrome. Methods: Salivary glands of 12 patients with Sjögren syndrome and 8 controls were studied. The mRNA and protein levels of α6β4 were determined by semiquantitative reverse transcriptase (RT)-PCR and western blot analysis, respectively. The subcellular localisation of α6β4 and laminin were evaluated by confocal microscopy. Results: In patients, no significant differences in α6 and β4 mRNA levels were detected. However, β4 integrin protein levels were significantly lower, whereas, changes in α6, were highly variable. In con