Background/Purpose: In primary Sjögren’s syndrome (pSS), labial minor salivary gland epithelial cells (LMSGEC) inappropriately express various molecules, including B7, HLA-DR, ICAM, as assessed previously by in-situ and in-vitro studies, indicating an epithelial cell activation. Sicca symptomatology is encountered in around 30% of rheumatoid arthritis patients (RA-sicca). We previously showed that RA-sicca labial minor salivary gland (LMSG) lesions differ from those observed in pSS, primarily by displaying higher frequency of antigen presenting cells (APCs) [1]. Also, in a subgroup of RA-sicca patients, LMSGECs were found to express the B7 molecule. Interestingly patients exhibiting B7-positive LMSGECs had distinct histopathological and clinicoserological characteristics resembling those observed in pSS. We sought to further investigate if there is, indeed, evidence of a pSS-like epithelial activation in this subgroup of RA-sicca patients.

Methods: Serial sections of LMSGs from 32 RA patients (2010 ACR criteria) with sicca symptoms were evaluated with immunohistochemistry for the presence of total T cells, helper and cytotoxic T cell subpopulations, B cells, macrophages (ΜΦ), interdigitating (iDC) and follicular dendritic cells (fDC) and for the expression of B7, HLA-DR and ICAM molecules. Stained cells and total mononuclear cells (MNC) were counted in the entire section. Counts were expressed as cell frequency (% of cell type/total infiltrating MNC numbers) and staining for activation markers was assessed on an arbitrary scale (0-1). Correlations between epithelial cell activation status and cell frequencies or clinicoserological features were performed.

Results: LMSGECs in 16/32 patients were triple (B7.1, HLA-DR, ICAM) positive while the rest were either single, double or triple negative. Triple positive patients versus the remaining ones had more severe LMSG lesions (focus score; Mann Whitney, p=0.05) and exhibited lower frequencies of MΦ, iDCs and fDCs (Table 1). No differences on clinicoserological features were observed among groups. Expression of the aforementioned molecules by primary cultured LMSGECs of the same patients will be confirmed by flow cytometry.

Conclusion: A distinct subgroup was identified within the RA-sicca patients. This is characterized by expression of activation markers by their LMSGECs and also by an immunohistopathological pattern resembling pSS rather than RA-sicca. In vitro studies of primary LMSGEC cultures will confirm if these cells are indeed activated in such patients. 1. GE Fragoulis, et al. Analysis of the cell populations composing the mononuclear cell infiltrates in the labial minor salivary glands from patients with rheumatoid arthritis and sicca syndrome. J Autoimmun. 2016 (In press)

Table 1: Epidemiological, clinicoserological and histopathological features. a. Kruskal-Wallis and chi-square test for continuous and categorical variables, respectively.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/evidence-of-labial-salivary-gland-epithelial-cell-activation-from-patients-with-rheumatoid-arthritis-and-sicca-symptomatology/