Objectives: TAM receptor tyrosine kinases (Tyro3, Axl, MerTK) are known for their role in the phagocytosis of apoptotic bodies, modulation of inflammation, and regulation of innate and adaptive immunity. The association of TAM signaling with Sjögren’s syndrome (SS) has not been well studied, so this study attempted to evaluate the clinical significance of MerTK and Tyro3 expression in the minor salivary glands of SS patients.

Methods: Sociodemographic data of 74 SS patients were obtained, and glandular and extraglandular manifestations and laboratory findings were documented. Minor salivary gland biopsies were performed in all patients, and the European League Against Rheumatism SS disease activity index (ESSDAI) and the SS disease damage index (SSDDI) were recorded. MerTK and Tyro3 expression was semi-quantitatively measured using immunohistochemical staining in the minor salivary glands.

Results: Of the 74 subjects, greater expression of MerTK and Tyro3 was observed in the minor salivary glands of patients with SS in 39.2% (29/74) and 13.5% (10/74), respectively. Greater expression of MerTK was associated with increased levels of IgG and anti-SS-A titers (p = 0.004 and p < 0.001, respectively). A higher focus score and ESSDAI and SSDDI values at the time of biopsy were also associated with higher MerTK expression levels. However, Tyro3 expression levels were not related to these clinical and laboratory parameters.

Conclusion: Among TAM receptors, MerTK within the lymphocytic infiltrates of SS patients was associated with several laboratory features of the disease, clinical disease activity, and organ damage. Thus, MerTK levels may be a useful marker to predict the prognosis of patients with SS.

REFERENCES: NIL.

Acknowledgements: NIL.

Disclosure of Interests: None declared.