AB0157 Targeting t-cell trafficking in a murine model of sjÖgren’s syndrome
Authors: J. Campos, S. Nayar, M. Chimen, V. Iannizzotto, H.M. McGettrick, B. Fisher, S.J. Bowman, C.D. Buckley, G.E. Rainger, F. Barone
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Salivary glands of primary Sjögren's syndrome (pSS) are characterised by complex leukocyte infiltration organised into tertiary lymphoid structures (TLS). The mechanisms regulating leukocyte trafficking into inflamed salivary glands are poorly described, but dysregulated T-cell recruitment during inflammation is believed to contribute to disease onset and chronicity. We recently described a homeostatic pathway in which a B cell-derived peptide (PEPITEM), secreted in response to adiponectin, regulates T-cell trafficking during inflammation via sphingosine-1-phosphate activity on endothelial cells<sup>1</sup>. Disruption of this pathway by downregulation of adiponectin receptors on circulating B cells has been demonstrated in type-1 diabetes and rheumatoid arthritis, suggesting a potential role for PEPITEM in the pathogenesis of autoimmune diseases, and indicating a role for adiponectin receptors as biomarkers in these conditions<sup>1</sup>. <h3>Objectives</h3> We aimed to investigate the efficacy of PEPITEM as an inhibitor of T-cell trafficking in an inducible animal model of salivary gland inflammation that mimics the histological features of pSS, and to investigate the potential translatability of this pathway in patients with pSS. <h3>Methods</h3> Submandibular salivary glands of C57BL/6 mice were intra-ductally cannulated with luciferase-encoding replication-deficient adenovirus to induce TLS formation as previously described<sup>2</sup>. Mice were administered daily either PBS or PEPITEM by intraperitoneal injection from day 0, and their salivary glands dissected at day 5 post cannulation. T-cell infiltration into salivary glands was assessed using a combination of flow cytometry, immunofluorescence, and qRT-PCR for inflammatory chemokines. <h3>Results</h3> B cells in sera from cannulated animals express lower levels of both adiponectin receptors 1 and 2 in comparison with non-inflamed control mice. In cannulated animals treated with PEPITEM, histological analysis of salivary glands revealed fewer, as well as less aggregated, infiltrating T cells. Both CD4 +and CD8+numbers were significantly lower in the salivary glands of PEPITEM-treated animals. Furthermore, administration of PEPITEM also decreased mRNA transcripts for lymphotoxin beta, IL-7, lymphoid chemokines (CCL19 and CXCL13) and T-cell chemokine receptor CCR7, cytokines and chemokines known to regulate ectopic lymphoneogenesis in pSS. Samples from pSS patients are currently being assessed to validate the relevance of this pathway in pSS. <h3>Conclusions</h3> These results demonstrate that administration of exogenous PEPITEM can reduce T-cell influx into salivary glands. This may represent a rescue of the homeostatic regulation of leukocyte trafficking which is disrupted in inflammation. Our work suggests that PEPITEM should be considered to address therapeutic needs in chronic inflammatory conditions, and that the detection of decreased levels of adiponectin receptors could serve as a biomarker in pSS. <h3>References</h3> [1] Chimen, McGettrick, et al. Nat Med. 2015;21(5):467–475. [2] Bombardieri, Barone, et al. J. Immunol. 2012;189:3767–3776. <h3>Disclosure of Interest</h3> None declared