Increased TLR9 protein level and upregulated serum cytokines IL-10 and IFN1A in systemic lupus erythematous patients.

OBJECTIVE

To investigate the association between serum TLR7 and TLR9 levels and previous viral infections, disease activity, and proinflammatory cytokine levels in SLE patients.

METHODS

A cross-sectional observational study was conducted in patients with SLE and healthy controls. Data on previous infections, disease activity, and clinical parameters were collected. Serum TLR7, TLR9, interleukin-10 (IL-10), and interferon-α (IFN-α) levels were measured by ELISA.

RESULTS

TLR9 levels were significantly higher in SLE patients than in controls (P<0.001). TLR7 levels did not differ between groups but showed a positive association with age (P<0.001). No associations were found between TLR7 or TLR9 levels and CRP, ESR, anti-dsDNA, ENAs, antiphospholipid antibodies, disease activity, previous infections, or disease duration. Lower TLR7 levels were observed in patients with antiphospholipid syndrome (P=0.001). Elevated TLR9 levels were significantly associated with increased IL-10 and IFN-α (P<0.001). TLR7 was not associated with IFN-α, although a trend toward higher levels was observed with elevated IL-10.

CONCLUSION

TLR9 is elevated in SLE and correlates with IL-10 and IFN-α, while TLR7 increases with age. .