Salivary anti-Ro60 and anti-Ro52 antibody profiles to diagnose Sjogren's Syndrome

Abstract

Simple and non-invasive saliva-based diagnostics may be useful for the identification, understanding, and monitoring of autoimmune and infectious diseases. Previously, Luciferase Immunoprecipitation Systems (LIPS) were used for sensitive detection of patient serum autoantibodies in Sjögren's Syndrome (SjS), a chronic autoimmune disease affecting the salivary and lacrimal glands. Here we explored the ability of LIPS to diagnose SjS based on IgG autoantibodies in patient saliva. From LIPS testing, anti-Ro60 autoantibodies were detected in the saliva of 70% (19/27) of SjS patients with 96% specificity. Positive anti-Ro60 autoantibodies were also found in 70% of the matched serum samples (96% specificity). LIPS detected Ro52 autoantibodies in the saliva and serum of 67% of SjS patients with 100% specificity. Overall, the autoantibody titers in saliva were approximately 4000-fold lower by volume than serum, but still distinguished seropositive patients from controls. These results suggest that LIPS salivary-based testing for SjS autoantibodies is a practical alternative to serum and compatible with point-of-care testing.

Figure 1.

LIPS detection of anti-Ro60 autoantibodies in saliva and sera. SjS patients’ (N = 27) and healthy control individuals’ (N = 27) saliva (A) and sera (C) were evaluated for anti-Ro60 autoantibodies by LIPS. Each circle or square symbol represents an individual healthy control or SjS patient sample, respectively. A cut-off, shown by the long solid line (A and C), was calculated by ROC analysis for saliva (B) and sera (D). The short solid lines indicate the geometric mean titer of each group.

Figure 2.

Comparison of anti-Ro60 autoantibody titers in sera and saliva in SjS patients. Titers for 19 SjS patients with significant anti-Ro60 autoantibody titers in both sera (black bars) and saliva (grey bars) are shown. Patients are shown in rank order by serum anti-Ro60 autoantibody titer. Patient numbers are shown on the x-axis.

Figure 3.

LIPS detection of anti-Ro52 autoantibodies in saliva and sera. SjS patients’ (N = 27) and healthy control individuals’ (N = 27) saliva (A) and sera (B) were evaluated for anti-Ro52 autoantibodies by LIPS. For autoantibody evaluation in saliva, the full-length Ro52 protein was used. For autoantibody evaluation in sera, an N-terminal fragment of Ro52, designated Ro52-Δ1, was used. Each circle or square symbol represents an individual healthy control or SjS patient sample, respectively. A cut-off, indicated by the long solid line, was calculated by ROC analysis. The short solid lines indicate the geometric mean titer of each group.