The simultaneous presence of serum anti-SSA/Ro and upregulated salivary TRIM29 provide high diagnostic accuracy in primary Sjögren syndrome (pSS),according to study results published in PLoS One.
Liquid chromatography tandem mass spectrometry technique in whole saliva was used to collect protein data from 24 patients with pSS and 16 patients with pSS symptoms but who did not fulfill the American College of Rheumatology/ European Alliance of Associations for Rheumatology (ACR/EULAR) classification criteria (non-pSS group). Researchers used enzyme-linked immunosorbent assays to measure serum anti-SSA/Ro antibody. Receiver operating characteristic curve (ROC) value was calculated for combined biomarkers.
All patients in the pSS group, along with 3 participants in the non-pSS group, tested positive for serum anti-SSA/Ro. The combination of upregulated TRIM29 levels in saliva plus anti-SSA/Ro antibodies in serum produced the highest ROC value, with an area under the curve (AUC) of 0.995 (95% CI, 0.98-1.00; P =2.0E-7 and SE 0.007). The optimal sensitivity and specificity for this combination was within the interval of 91% to100%. Researchers noted that this TRIM29 plus anti-SSA/Ro was superior to other protein biomarker candidates, including neutrophil elastase, calreticulin, and clusterin.
Levels of TRIM29 alone also enabled differentiation between pSS and non-pSS, with an AUC of 0.88 (95% CI, 0.77-0.995; P =.0001 and SE 0.06).
In this cohort, anti-SSA/Ro antibodies in serum showed an AUC of 0.906, with a sensitivity of 100% and specificity of 81%.
Study limitations included a small sample size and the lack of information on the specific Ro subtype.
Researchers concluded that this biomarker combination enabled 99.5% differentiation from patients with pSS symptoms but without a diagnosis of pSS.
They added, “…this is based on a small cohort and costly in-depth proteomic analysis, and the applicability of TRIM29 as a biomarker in pSS diagnostics therefore needs further validation and ideally development of point-of-care tests easy applicable for clinical usage.”
Sembler-Møller ML, Belstrøm D, Locht H, Pedersen AML. Combined serum anti-SSA/Ro and salivary TRIM29 reveals promising high diagnostic accuracy in patients with primary Sjögren’s syndrome. PLoS One. 2021;16(10):e0258428. doi:10.1371/journal.pone.0258428