P2Y2 receptor antagonism resolves sialadenitis and improves salivary flow in a Sjogren's syndrome mouse model

Objective: Sjogren's syndrome (SS) is a chronic autoimmune exocrinopathy characterized by lymphocytic infiltration of the salivary and lacrimal glands and decreased saliva and tear production. Previous studies indicate that the G protein-coupled P2Y(2) nucleotide receptor (P2Y(2)R) is upregulated in numerous models of salivary gland inflammation (i.e., sialadenitis), where it has been implicated as a key mediator of chronic inflammation. Here, we evaluate both systemic and localized P2Y(2)R antagonism as a means to resolve sialadenitis in the NOD. H-2(h4),IFN gamma(-/-),CD28(-/-) (NOD.H-2(h4) DKO) mouse model of SS. Design: Female 4.5 month old NOD.H-2(h4) DKO mice received daily intraperitoneal injections for 10 days of the selective P2Y(2)R antagonist, AR-C118925, or vehicle-only control. Single-dose localized intraglandular antagonist delivery into the Wharton's duct was also evaluated. Carbachol-induced saliva was measured and then submandibular glands (SMGs) were isolated and either fixed and paraffin-embedded for H&E staining, homogenized for RNA isolation or dissociated for flow cytometry analysis. Results: Intraperitoneal injection, but not localized intraglandular administration, of AR-C118925 significantly enhanced carbachol-induced salivation and reduced lymphocytic foci and immune cell markers in SMGs of 5 month old NOD.H-2(h4) DKO mice, compared to vehicle-injected control mice. We found that B cells represent the primary immune cell population in inflamed SMGs of NOD.H-2(h4) DKO mice that express elevated levels of P2Y(2)R compared to C57BL/6 control mice. We further demonstrate a role for P2Y(2)Rs in mediating B cell migration and the release of IgM. Conclusion: Our findings suggest that the P2Y(2)R represents a novel therapeutic target for the treatment of Sjogren's syndrome.

Automated summary

The P2Y(2)R antagonist AR-C118925 significantly enhances salivation and reduces lymphocytic foci and immune cell markers in SMGs of NOD.H-2(h4) DKO mice with SS. B cells are the primary immune cell population in inflamed SMGs expressing elevated levels of P2Y(2)R.