Yersinia infections and Graves’ disease

Abstract

Background. The most common thyroid disease, accompanied by thyrotoxicosis syndrome, is Graves' disease (GD). Information about the role of Yersinia in the development of this disease is contradictory.
 Aims. To study the significance of Yersinia (Y.) enterocolitica and Y. pseudotuberculosis in the development of Graves' disease.
 Materials and methods. 78 patients with GD. Identification of antibodies to Y. was carried out by the following methods: 1. agglutination test (AT) with suspensions of live virulent cultures Y. pseudotuberculosis, Y. enterocolitica O:3 and O:9; 2. indirect hemagglutination test (IHET) with the use of erythrocyte diagnosticum; 3. determination of IgA and IgG antibodies against pathogenicity factors of Y. enterocolitica strains by immunoblotting (30 patients with GD).
 Results. Diagnostically significant titers of antibodies to Y. pseudotuberculosis and Y. enterocolitica were obtained in all patients with GD by AT. The greatest total thyroid volume determined by ultrasound investigation (p = 0.010) and the maximum duration of the disease (p = 0.040) were determined in the group of patients with the maximum antibody titer. No significant relation was found between the titer of antibodies to Yersinia and the levels of thyroid hormones stimulating the thyroid antibodies.The test for detection of IgA antibodies by immunoblotting was negative in 30 patients with GD (9 patients with a titer of antibodies by AT 1:800 – 1:1600, 17 – 1:400, 4 – 1:200). In all cases with the maximum antibody titer in AT, the positive IgG antibodies to the antigens YopM (Yop2a), YopH (Yop2b), V-antigen, YopD were found. The GD duration in patients with negative titers of antibodies by the immunoblotting test was less than with the positive one (p = 0.010). The privative clinical and anamnestic data and negative results by IHET confirmed the absence of active and/or transferred Yersinia infections in all the examined patients with GD.
 Conclusions. The cross-reacting antibodies to the antigens of Y. enterocolitica are determined in the serum of GD patients by AT and immunoblotting. The diagnostic titer of these antibodies is more often detected in patients with greater GD duration and larger volume of the thyroid gland. The absence of a link between the titer of these antibodies and the levels of thyroid hormones, the antibodies to the thyrotropin receptors of pituitary, as well as negative results by IHET with a diagnosticum that does not contain outer membrane proteins of pathogenic Yersinia, deny the trigger role of Yersinia infections as an initiating factor in the development of GD.