THU0241 Decreased circulating CXCR3+CCR9+ th cells are associated with elevated levels of their ligands CXCL10 and CCL25 in the salivary gland of patients with SJÖGREN'S syndrome to potentially facilitate concerted migration
Authors: SL Blokland, MR Hillen, S Meller, B Homey, GM Smithson, AA Kruize, TR Radstake, JA van Roon
Journal: Annals of the Rheumatic Diseases (2017)

<h3>Background</h3> Primary Sjögren9s syndrome (pSS) is characterized by dryness and lymphocytic infiltration in the salivary glands. Both CXCR5+ T follicular helper (Tfh) cells and CCR9+ Tfh-like cells and their specific chemotactic ligands CXCL13 and CCL25 are present at increased levels in the salivary glands of pSS patients. Recently, we and others found that CCR9+ Th cells are elevated in pSS peripheral blood and co-express CXCR3 and other chemokine receptors, known to be differentially expressed by Th cell subsets. CCR9+ Th cells play an important role in mucosal immunity and have been shown to produce high levels of IFN-γ, like CXCR3+ Th1 cells. Since ligands of CXCR3 (CXCL9/10/11) are abundantly expressed in the salivary glands of pSS patients the potential role of this receptor in conjunction with CCL25 was studied in comparison with other chemokine receptors. <h3>Objectives</h3> To study potential chemokine interactions causing enhanced migration of CCR9+ T cells into the salivary glands in pSS. <h3>Methods</h3> CXCL10, CCL25, CXCL13, CCL17 and CCL20 mRNA and protein expression in the salivary gland of pSS and non-Sjögren9s sicca (nSS) patients was assessed (mRNA: n=9 vs n=9 and protein: n=26 vs n=34, respectively). Frequencies of CXCR3, CCR9, CXCR5, CCR4 and CCR6 expressing Th cells in blood of pSS patients and healthy controls were assessed by flow cytometry (n=11 vs n=11). Chemotaxis assays (n=3 HC, n=5 pSS) were performed to study migration induced by CXCL10 and CCL25. <h3>Results</h3> CCL25, CXCL10 and CXCL13 expression were increased in pSS compared to nSS patients, both at mRNA and protein level (all p≤0.02). CCL17 and CCL20 expression were low and detectable in only few patients. Protein levels of CXCL10 and CXCL13 correlated with lymphocytic focus scores and all 3 chemokines correlated with serum IgG levels in pSS (all p&lt;0.05). CCL25 protein levels strongly correlated with CXCL10 (r=0.545, p=0.004) but not with CXCL13. A relative decrease of CXCR3+ cells was found in the CCR9+ Th subset in the peripheral blood of pSS patients (p=0.04), which was most pronounced in the effector and effector memory subsets (64% vs 26%, p=0.03 and 51% vs 27% p=0.01, respectively). CCR4 or CCR6-expressing CCR9+ Th cells and CXCR3 or CCR6-expressing CXCR5+ Th cells were not decreased. To test the hypothesis that CXCR3 ligands and CCL25 facilitate migration, co-migration of lymphocytes in response to CXCL10 and CCL25 was studied. CXCL10 and CCL25 induced synergistic Th cell chemotaxis in vitro (p=0.02 and p&lt;0.01 as compared to CCL25 or CXCL10 only, respectively). <h3>Conclusions</h3> The decreased frequency of CXCR3+CCR9+ Th cells in blood of pSS patients may be due to a concerted action of overexpressed ligands at the site of inflammation. Elevated expression of ligands CXCL10 and CCL25 in the salivary gland and the synergistic effect on chemotaxis in vitro indicate a potential role for these chemokines in formation of lymphocytic infiltrates in exocrine glands of pSS patients. <h3>Disclosure of Interest</h3> None declared