The role of myeloid-derived suppressor cells in Sjögren's disease

Sjögren's Disease (SjD) is a chronic autoimmune disease characterized by exocrine glandular lymphocyte infiltration and functional damage, with a complex pathogenesis and immune cell imbalance as a key driver. Myeloid-derived suppressor cells (MDSCs), as heterogeneous immature myeloid cells, play an immunosuppressive function by secreting molecules such as arginase 1, nitric oxide, and reactive oxygen species, and play a dual role in tumor immune escape and autoimmune disease regulation. In recent years, studies have shown that the frequency of MDSCs increases abnormally in SjD patients and animal models, but their physiological function changes dynamically. For instance, MDSCs show immunosuppressive activity in the early stage of the disease, and in the late stage, their immunosuppressive property is impaired or even transformed into a pro-inflammatory phenotype and are therefore involved in the pathogenesis of SjD by regulating the balance of T cell subsets and the secretion of inflammatory factors. Nevertheless, the pathogenic role of MDSC in SjD is not fully understood, and some controversy remains, as well as many unanswered questions. This review summarizes the most recent literature on MDSCs in SjD, systematically reviews the phenotypic characteristics, metabolic and signaling remodeling mechanisms, treatment strategies associated with MDSCs, regulation between MDSCs and key immune cells and role of MDSCs in systemic manifestations in SjD, and discusses the relationship between MDSCs and SjD.