Increased risk of malignancy and osteoporosis in primary Sjögren's syndrome with thyroid diseases: potential implication from T cells.

OBJECTIVES

To evaluate the impact of thyroid diseases (TDs) on the comorbidities incidence and immune system of patients with primary SS (pSS).

METHODS

A total of 329 patients diagnosed with pSS who were admitted between January 2018 and September 2023 were evaluated. The patients were divided into two groups: those with and without TD. Clinical data at the onset of SS were recorded. Kaplan-Meier method and Cox proportional hazards model were utilized for survival analysis. Flow cytometry and immunofluorescence measurements were used to analyse the lymphocyte subtypes.

RESULTS

Of the 329 patients, 109 had TD. The most common types of TD were thyroid nodules (40.4%) and autoimmune thyroid diseases (AITDs) (28.4%). Patients with TD exhibited a significantly elevated incidence risk of malignancy (14.7% vs. 6.4%, P = 0.01) and osteoporosis (OP) (23.9% vs. 14.1%, P = 0.03). TD comorbidity was an independent risk factor of malignancy (HR 4.7, 95% CI 1.1-19.3, P = 0.03) and OP (HR 3.7, 95% CI 1.3-10.2, P = 0.01). Patients with SS and TD exhibited a higher ratio of programmed death-1 (PD1) + subsets of total CD3+ T cells, Th and Tc cells (all P = 0.03), as well as a lower ratio of unswitched memory B cells (P = 0.01) in peripheral blood. The ratio of PD1+ subsets of Th cells in salivary glands also exhibited a significantly increase in these patients compared with those without TD (P = 0.03) and the controls (P < 0.01).

CONCLUSION

The incidence risk of malignancy and OP was significantly elevated in pSS patients with TD. The significant elevated proportions of PD1+ T cells may influence the occurrence of this process.