Application of LIPUS to salivary glands

Abstract

Sjögren syndrome (SS) is one of the most common unexplained intractable autoimmune diseases occurring in middle-aged women. Patients with SS manifest progressive dryness symptoms due to insufficient salivary and lacrimal secretions. Xerostomia, defined as dry mouth, is a subjective symptom that most commonly appears in SS patients. Available causal treatment of xerostomia has been limited, and then the establishment of a causal treatment with no or less side effect is urgently needed. The effect of noninvasive low-intensity pulsed ultrasound (LIPUS) on soft tissues has received much attention for promoting effects on soft tissue healing. Thus, LIPUS may have considerable clinical potential for treatment of injured or pathological soft tissues including salivary gland. Recently, we investigated the effects of LIPUS on salivary gland cells and demonstrated that the expression of aquaporin 5 (AQP5), a water channel protein, in human salivary gland acinar cells was inhibited by TNF-α treatment, whereas it was recovered following LIPUS treatment. In addition, our in vivo study using MRL/lpr mice, the best model for SS, suggests that LIPUS treatment restored salivary gland secretion volumes in older MRL/lpr mice, thereby promoting an anti-inflammatory response and improving AQP5 dysfunction. It is concluded that LIPUS stimulation may represent a treatment strategy for inflammatory diseases of salivary glands, including xerostomia in SS.