Identification of Plasma Biomarkers for B7 Family Members Associated With Primary Sjögren's Syndrome

To evaluate the plasma levels of B7 family members (B7-H1, B7-H2, B7-H3, B7-H4, B7-H5, and B7-H6) in primary Sjögren's syndrome (pSS) patients and investigate their potential associations with disease activity.

This study included 69 pSS patients and 59 healthy participants. The expression levels of six costimulatory molecules were measured using enzyme-linked immunosorbent assay (ELISA). Furthermore, we examined the potential correlations between the levels of soluble B7-H1 (sB7-H1), sB7-H2, sB7-H3, sB7-H4, sB7-H5, and sB7-H6 with clinical symptoms and laboratory parameters.

pSS patients showed significantly higher expression levels of sB7-H1, sB7-H2, and sB7-H5 compared to healthy controls (HCs) (p < 0.05). In contrast, sB7-H6 expression levels were significantly lower in pSS patients (p < 0.05). Correlation analysis revealed that sB7-H1 exhibited positive associations with RF, IgG, CRP, and ESR. sB7-H2 showed significant positive correlations with both IgG and ESR, while sB7-H3 exhibited a negative correlation with RF and a positive correlation with CRP. Additionally, sB7-H5 revealed significant positive correlations with RF, IgG, and ESR. In contrast, sB7-H6 demonstrated negative correlations with IgG, IgA, and ESR. ESSDAI-related analysis revealed a significant positive correlation between sB7-H1 and ESSDAI (p < 0.05), while sB7-H6 exhibited a significant negative correlation with ESSDAI (p < 0.05). sB7-H1 exhibited an increasing trend in patients with clinical symptoms such as xerostomia, xerophthalmia, decayed tooth, fatigue, arthralgia, and glandular swelling, as well as in those with high IgG levels and positivity for anti-SSB/La, anti-SSA/Ro60, and anti-SSA/Ro52. Conversely, sB7-H6 demonstrated a declining trend in these patient groups. The combined use of sB7-H1 and sB7-H6 demonstrates good effectiveness in diagnosing pSS and distinguishing disease activity levels.

Our results indicated that patients with pSS exhibited elevated expression of sB7-H1 and a reduction in sB7-H6. These changes were found to correlate with clinical symptoms and laboratory parameters, suggesting that sB7-H1 and sB7-H6 could potentially serve as biomarkers for pSS.