Organ-specific autoantibodies in non-organ-specific autoimmune diseases with special reference to rheumatoid arthritis

The prevalence of thyroid autoantibodies in autoimmune connective tissue diseases: a systematic review and meta-analysis

AIM

Patients with autoimmune connective tissue disease (ACTD) may have anti-thyroid peroxidase antibody (TPOAb) and anti-thyroglobulin antibody (TgAb). This study aimed to compare the prevalence of thyroid autoantibodies in ACTD patients and controls.

METHODS

All case-control studies published between 1980 and 2019 in English were searched from Medline, Embase, Web of Science, PubMed databases for meta-analysis and subgroup analyses.

RESULTS

Total 10,321 ACTD cases and 12,949 healthy controls were included, and the prevalence of thyroid autoantibody positivity was higher in ACTD patients than in controls. Subgroup analysis revealed positive association between TgAb and ACTD in populations from all continents including European, Asian, African, and American. In addition, we found positive association between TgAb positivity and most ACTD cases including RA, SLE, pSS, and UCTD, positive association between TPOAb positivity and all ACTD cases including RA, SLE, pSS, SSc, and UCTD, and positive association between TPOAb positivity and ACTD in European, Asian, and African but not in American populations.

CONCLUSION

Thyroid autoantibodies are more prevalent in ACTD patients than in healthy controls. It is important to screen patients with ACTD for the presence of thyroid autoimmunity, and perform thyroid function tests in clinical evaluation of ACTD patients.

BAFF overexpression is associated with autoantibody production in autoimmune diseases

The B-cell activity factor (BAFF) acts as a positive regulator of B-cell function. To gain further insight into the understanding of B-cell hyperactivity in autoimmune diseases, the serum level of BAFF was determined in 43 systemic lupus erythematosus (SLE) patients, 58 primary Sjögren's syndrome (pSS) patients, 28 rheumatoid arthritis (RA) patients, and 68 normal control subjects using an in-house sandwich ELISA. A commercial kit was used to detect soluble CD23 (sCD23) reflecting B-cell activation. In-house assays for the detection of autoantibodies also were used. We found an increased level of BAFF in SLE, pSS, and RA sera compared with normal subjects (respectively, 10.6 +/- 8.5, 15.8 +/- 12.9, 9.7 +/- 1.5 ng/mL vs. 4.6 +/- 2.9 ng/mL, P < .001). sCD23 released on B-cell activation also was found to be elevated in SLE, pSS, and RA compared with normal sera. However, no correlation was found between the circulating BAFF and the level of sCD23. By contrast, we observed that high levels of BAFF were associated with the presence of autoantibodies (anti-double-stranded DNA antibodies in SLE, anti-SSA antibodies in pSS, and rheumatoid factors in RA). Our data suggest that BAFF is influential in driving antibody production rather than activation of the B lymphocytes in autoimmune diseases.

Thyroid dysfunction in primary Sjögren's syndrome: a long-term followup study

OBJECTIVE

To evaluate the prevalence of thyroid dysfunction and related autoantibodies in patients with primary Sjögren's syndrome (pSS), and to determine whether these abnormalities develop over time.

METHODS

pSS patients (n = 137) and controls (n = 120) were investigated for thyroid dysfunction and for the presence of anti-thyroid peroxidase antibody (anti-TPO) and antithyroglobulin antibody (ATG). Followup time for patients was 1-16 years, and 72 of the 120 controls were reevaluated 3 years after initial evaluation.

RESULTS

Thyroid disease was more frequent in the pSS patients than in the controls (30% versus 4%; P < 10(-4)), as were anti-TPO and ATG (11% versus 3%; P < 0.02, and 3% versus 1%, not significant). Ten of 107 euthyroid pSS patients dropped out of the study, and thyroid dysfunction became apparent at followup in 12 of the remaining 97. Most of the patients with thyroid-related autoantibodies at entry developed autoimmune thyroid disease thereafter.

CONCLUSION

Thyroid dysfunction is frequent in pSS patients, and those prone to develop thyroid disorders are identified by thyroid-related autoantibodies, or by rheumatoid factor and anti-Ro/SSA activity.

A prospective evaluation of antithyroid antibody prevalence in 100 patients with rheumatoid arthritis

The prevalence of thyroid antibodies in 100 patients with rheumatoid arthritis in Northern Norway was studied. The serological data were compared with those from a major population survey in the same area. Compared to the prevalence in the normal population, the present study demonstrates that patients with rheumatoid arthritis have a higher prevalence of antibodies to both thyroid microsomal antigen and thyroglobulin.

Histologic and electron microscopic characterization of the antiperinuclear factor antigen

The presence of the antiperinuclear factor, an autoantibody that recognizes cytoplasmic antigens, was detected in sera from patients with rheumatoid arthritis (59%), seronegative rheumatoid arthritis (36%), systemic lupus erythematosus (46%), systemic sclerosis (26%), and in nonautoimmune controls (10%). The antigenic perinuclear granules were found in the stratum intermedium layer of the buccal mucosa. Granules exhibited histologic features of nucleoproteins, stained for ribonucleoprotein, and showed the ultrastructural characteristics of aggregated rough endoplasmic reticulum. The antiperinuclear factor may recognize a common autoantigen in connective tissue disease.

Activation of peripheral blood lymphocytes in patients with primary Sjögren's syndrome

The peripheral blood from 15 patients with primary Sjögren's syndrome and from 15 matched controls was examined for the presence of activated T and B lymphocytes, by using monoclonal antibodies directed to interleukin-2 (IL-2) and transferrin receptors, and to HLA-DR determinants. The number of circulating positive-T cells was significantly greater in the patients than in the controls, irrespective of disease activity. There were more of the CD8 cells than of the CD4 cells that expressed IL-2 receptors. There was a small but significant increase in activated B cells in the patients, since this population is virtually absent from the normal blood.