GFP Adeno-associated virus(AAV Serotype 2)

Sjögren's syndrome (SjD) is a chronic autoimmune sialadenitis that results in salivary gland hypofunction and symptoms of dry mouth. Previous studies have shown that lysosomal-associated membrane protein 3 (LAMP3) overexpression is associated with the development of SjD-related salivary gland hypofunction. Here, analysis of salivary gland samples from SjD patients revealed that salivary gland hypofunction was associated with decreased expression of sodium-potassium-chloride cotransporter 1 (NKCC1) and aquaporin 5 (AQP5), two membrane proteins involved in saliva secretion. Furthermore, the researchers found that LAMP3 overexpression enhanced gene transfer by increasing internalization of adeno-associated virus serotype 2 (AAV2) by promoting the endolysosomal pathway. Retrograde insertion of an AAV2 vector encoding the AQP1 gene (AAV2-AQP1) into salivary glands induced glandular AQP1 expression sufficient to restore saliva flow in LAMP3-overexpressing mice. LAMP3 may play a key role in the development of salivary gland hypofunction in SjD by promoting lysosomal degradation of NKCC1 and AQP5. But it can also enhance AAV2-mediated gene transfer to restore fluid flow by inducing AQP1 expression. These findings suggest that AAV2-AQP1 gene therapy could be used to reverse salivary gland function in SjD patients.

Here, to test whether AAV-mediated gene therapy could be effective in treating LAMP3-related salivary gland hypofunction, researchers studied the effects of AAV2-AQP1 gene therapy in LAMP3-overexpressing mice. AAV2-AQP1 or control AAV2-GFP was also delivered to the submandibular gland of C57BL/6 mice via retrograde cannulation 7 months after retrograde catheter instillation of AAV2-LAMP3 (Figure 1A). AAV2-AQP1 treatment significantly restored pilocarpine-stimulated SFR compared with control treatment (AAV2-GFP), an effect that was visible after 1 month and persisted for at least 3 months (Figure 1B). Although AAV2-AQP1 treatment induced glandular AQP1 protein expression in AAV2-AQP1-treated mice compared with control mice, it did not affect NKCC1 and AQP5 expression (Figure 1C, D). AAV2-AQP1 treatment did not significantly alter serum anti-Ro/SSA antibody levels nor the size of the lymphocytic infiltration area in the gland compared with control treatment (AAV2-GFP) and baseline (Figure 1E, F).

Figure 1. AAV2-AQP1 gene therapy restores salivary flow rate in LAMP3-overexpressing mice. (Nakamura H, et al., 2022)