Background/Purpose A positive salivary gland (SG) biopsy with a focus score of ≥1 is the only widely accepted pathological finding confirming the salivary gland component of Sjögren’s syndrome (SS). SG biopsies can yield important information about the autoimmune activity and severity of the disease process including identification of germinal centers that may be possible predictors of lymphoma development. Moreover, adipocytes can occupy a large percentage of the gland area, and at present, little is known about their significance in SS lesions. The aim of the present study was to characterize adipose tissue infiltration in labial SG biopsies of patients under evaluation for SS.

Methods 3-5 SGs were excised from the lower lip following a standard procedure. Evaluation of the glands was performed by one oral pathologist and included area assessment and counting of foci (dense aggregates of 50 or more mononuclear cells), as well as evaluation of acinar atrophy, fatty replacement, interstitial fibrosis, nonspecific chronic inflammation, and scattered or focal infiltrates of mononuclear cells adjacent to tissue not appearing normal. Patients were classified according to the AECG classification criteria and included 28 SS patients and 28 subjects evaluated for SS but not fulfilling the criteria (non-SS controls). IL-6 (rabbit polyclonal, Abcam-ab6672) expression was assessed by immunohistochemical staining of paraffin embedded salivary gland biopsies from SS patients and non-SS controls.

Results Fatty replacement was evident in all SS patients possessing autoantibodies (RoSS-A and/or LaSS-B) as well as a positive SG biopsy (focus score ≥1), whereas 62% of the SS patients having autoantibodies but a negative biopsy showed fatty infiltration. Less than one third of the non-SS controls demonstrated fatty replacement. Overall, the SS group (mean age 53.0 years) had a significantly higher degree (p-value 0.0003) of fatty infiltration than the non-SS controls (mean age 54.8 years). Interestingly, adipocytes were located in IL-6 rich areas, and scattered IL-6 positive adipocytes were detected.

Conclusion Our observations indicate that although fatty infiltration may occur in the repair process of glandular epithelium, fat deposition seems to be more extensive in salivary glands affected by SS. The important finding of IL-6 positive adipocytes supports the notion that adipocytes have the potential to secrete IL-6, thus being active contributors to immune reactions. Further analysis to delineate possible roles of adipocytes in the autoimmune salivary gland microenvironment is needed. Moreover, assessing the adipose tissue replacement may be helpful for diagnostic accuracy in SS.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/adipose-tissue-is-prominent-in-salivary-glands-of-sjogrens-syndrome-patients-and-appears-to-influence-the-autoimmune-microenvironment-in-these-organs/