Background/Purpose: The hallmark clinical complaints in Sjögren’s syndrome (SS) are dry mouth and dry eyes related to salivary and lacrimal glands dysfunction. Reduced salivation reflects underlying fluid secretion deficits in the membrane permeability of acinar cells. In several animal models, including SS, increasing the membrane permeability using gene transfer of human aquaporin 1 (hAQP1) effectively restores fluid secretion. Indeed, hAQP1 gene transfer improved salivation and dry mouth in patients with radiation-induced xerostomia. Presently, there are no long-term effective therapies for most patients with dry mouth. To address this unmet clinical need we tested the ability of ex vivo adeno-associated virus serotype-2 (AAV2)-hAQP1 gene transfer to restore fluid secretion in human labial salivary glands (LSG) from SS patients and identify predictive molecular signatures of responsiveness. We hypothesize that by restoring water permeability in acinar cells of salivary glands it is possible to correct salivary hypofunction in SS.

Methods: Sixteen (N=16) subjects provided informed consent and were evaluated in the NIDCR Sjögren’s Syndrome Clinic. Subjects received comprehensive rheumatologic, ophthalmologic, and oral/salivary evaluations including LSG biopsies; nine subjects met the 2016 American College of Rheumatology SS criteria. LSG biopsies were divided into RNAlater for storage or immediately micro-dissected into lobule preparations for ex vivo culture. Lobules were transferred to 24-well transwell plates and cultured at the air-media interface. Two hours after equilibration, LSG lobules were transduced with 6.25E+11 particles of AAV2-hAQP1 and 1.35E+11 AAV2-mCherry or 1.35E+11 AAV2-mCherry alone as a control. After 24 hours of transduction, the volume change response to 2uM carbachol was measured. Remaining lobules were fixed in 4% paraformaldehyde for immunofluorescence (IF) or preserved in RNAlater for RNA sequencing.

Results: AAV2-hAQP1 transduction corrected both SS (p = 0.02) and non-SS (p < 0.01) LSG fluid secretion deficits up to 80% of normal. AAV2-hAQP1 transduction was confirmed using IF for hAQP1 expression and mCherry fluorescence in the acinar tissues. The RNA-sequencing analysis showed that responders to AQP1 transduction have a lower molecular signature for mesenchymal markers.

Conclusion: Our data suggest that, in the context of SS pathophysiology with sufficient secretory parenchyma in the glands of patients, SS salivary hypofunction can be recovered using AAV2-hAQP1.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/correction-of-sjogrens-syndrome-fluid-secretion-deficits-in-salivary-gland-acinar-cells-by-aquaporin-1-gene-transfer/