Avidity of thyroglobulin antibody in sera from patients with Hashimoto's thyroiditis with different thyroid functional status

The anti-carbamylated protein antibody response is of overall low avidity despite extensive isotype switching

Objective

To better understand the contribution of autoantibodies in RA and the biology of their responses, we evaluated the avidity of the anti-carbamylated protein (anti-CarP) antibody response.

Methods

The avidity of anti-CarP antibody, ACPA and anti-tetanus toxoid IgG were determined using elution assays. Anti-CarP IgG avidity was measured in sera of 107 RA patients, 15 paired SF and serum samples and 8 serially sampled sera before and after disease onset.

Results

The avidity of anti-CarP IgG is low compared with the avidity of anti-tetanus toxoid IgG present in the same sera. Likewise, although less pronounced, anti-CarP also displayed a lower avidity as compared with the avidity of ACPA IgG. No difference in anti-CarP IgG avidity is observed between ACPA positive or ACPA negative patients. Anti-CarP IgG avidity is higher in anti-CarP IgM-negative compared with IgM-positive individuals. Furthermore, the anti-CarP avidity in serum is higher than in SF. Using samples of individuals that over time developed RA we observed no anti-CarP avidity maturation in the years before disease onset. In contrast to ACPA avidity, the anti-CarP avidity is not associated with severity of joint destruction.

Conclusion

The anti-CarP response is of overall low avidity, even lower than the ACPA IgG avidity, and does not show apparent avidity maturation before or around disease onset. Overall, isotype switch and avidity maturation seem to be uncoupled as isotype switch occurs without avidity maturation, pointing towards a commonality in the regulation of both autoantibody responses as opposed to the pathways governing recall responses.

Is only Thyroid Peroxidase Antibody Sufficient for Diagnosing Chronic Lymphocytic Thyroiditis?

Objectives:

Recently, only anti-thyroid peroxidase (anti-TPO) has been suggested as an autoantibody in the diagnosis of chronic lymphocytic thyroiditis (CLT). In contrast, anti-thyroglobulin (anti-Tg) positivity has also been reported to be important. To evaluate this relationship more clearly, we planned to retrospectively investigate the autoantibody levels of the patients who underwent thyroid surgery for various reasons and those with CLT in postoperative pathology.

Methods:

We evaluated 670 patients who underwent thyroid surgery (total/subtotal thyroidectomy) for various reasons at our hospital between January 2015 and March 2017. Patients with indications of Graves’ disease, toxic multinodular goiter, and all malignancies except for thyroid papillary carcinoma (TPC) were excluded. Eighty-nine patients whose pathology findings were compatible with CLT and preoperative thyroid autoantibodies were identified enrolled in to the study. Patients with absence and presence of thyroid antibodies were included in the seronegative CLT group and seropositive CLT group, respectively. In addition, patients were divided into thyroid papillary carcinoma (TPC) and benign groups.

Results:

According to the study criteria, 89 (83 females, six males) (mean age, 46.08±11.19 years) patients who had preoperatively identified autoantibodies were detected. Anti-TPO positivity was found in 47 (52.8%) cases, whereas anti-Tg positivity was found in 49 (55.1%). Only anti-TPO positivity was found in 18 (20.2%) cases, whereas only anti-Tg positivity was detected in 20 (22.5%). Twenty-two (24.7%) of the patients were seronegative. On comparing the seronegative and seropositive groups, seronegativity was more frequent in male patients (p=0.03). Thyroid-stimulating hormone was found to be significantly higher in the seropositive group (p=0.01). TPC was detected in 36 (40.4%) of all cases. No difference regarding age, thyroid function tests, and antibody levels was found between the benign and TPC groups.

Conclusion:

Although all of our cases were histopathologically diagnosed with CLT, serologically, 75.3% of thyroid autoimmunities could be shown when both antibodies were evaluated together. When only anti-TPO was considered, this rate decreased to 52.8%. Therefore, anti-Tg appears to be still important in showing autoimmunity. Prospective studies are needed to evaluate this relationship more clearly.

Relationship of paratracheal lymph nodes with the progression of chronic autoimmune thyroiditis: 5-year follow-up results

Background/aim: To examine changes in paratracheal lymph nodes (PLNs) and the relationship with the course of the disease in patients with chronic autoimmune thyroiditis (CAT) 5 years after diagnosis. Materials and methods: A total of 169 patients with newly diagnosed CAT and 53 healthy subjects were included in the study. All patients underwent ultrasonographic (US) examinations of the thyroid, paratracheal regions, and examined thyroid function tests. Eighty-four patients who were euthyroid at baseline and who were contacted 5 years after the diagnosis were reevaluated by US and thyroid function tests. Results: The PLNs frequency was significantly higher in the CAT group than the controls (75.1 % vs. 30.1 %, P < 0.001). Among the 84 patients who were euthyroid at the time of diagnosis and were contacted again after 5 years, 15 developed hypothyroidism. Initially, PLNs were present in all patients who developed hypothyroidism and were significantly higher than in those who remained euthyroid (respectively 100% vs. 68.7%, P = 0.009). PLN presence and PLN volume in patients who were euthyroid at baseline predicted hypothyroidism at the end of 5 years. Conclusion: PLNs may be used as an indicator of disease progression. In addition, patient age and baseline TSH levels are other factors that predict the development of hypothyroidism in time.

CD32b expression is down-regulated on double-negative memory B cells in patients with Hashimoto's thyroiditis

Inhibitory CD32b receptors on B cells are critical for humoral immunity. The humoral response plays a role in the pathogenesis of Hashimoto's thyroiditis (HT). This study aimed to investigate B cell subset distribution and CD32b expression within these subsets in HT patients. B cell subset distribution and CD32b expression were analyzed in 60 HT patients and 21 healthy donors. Subset distribution and CD32b expression following stimulation with α-Ig and α-CD40 were also assessed. The percentage of double-negative (DN) memory cells was increased in the HT patients, while the expression level of CD32b on DN memory cells was decreased. Redistribution of B cell subsets was detected in response to stimulation with α-Ig. In addition, the expression level of CD32b was reduced following α-CD40 stimulation. These results suggest that abnormal B cell subset distribution and decreased CD32b expression on DN memory cells might be involved in the pathogenesis of HT.

The expression of Fcγ receptors in Hashimoto's thyroiditis

The pathophysiological mechanism underlying Hashimoto's thyroiditis (HT) is still unclear. Thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) are diagnostic hallmarks of HT. These IgG antibodies regulate the balance of immunologic tolerance and autoimmunity via Fcγ receptors (FcγRs). The aim of our study was to investigate the role of FcγRs in the pathogenesis of HT. The percentage of peripheral blood mononuclear cells (PBMCs) from HT patients bearing FcγRII was significantly lower than that seen in healthy donors, and the mean fluorescence intensity (MFI) value of FcγRII on PBMCs from HT patients was significantly higher. The percentage of PBMCs positive for FcγRIII also was significantly higher in HT patients, and the percentage of B cells bearing FcγRIIB in HT patients was significantly lower than that seen in healthy donors. Our study therefore provides evidence for FcγRs, especially FcγRIIB, being involved in the pathogenesis of HT.

A new type of natural bispecific antibody with potential protective effect in Hashimoto thyroiditis

CONTEXT

As a new antibody concept, natural bispecific antibodies (nBsAbs) have been detected in long-term passive immunization and some diseases, but their potential immunomodulatory role remains unclear. Hashimoto thyroiditis (HT) appears to fulfill the condition for nBsAb production but has not yet been characterized.

OBJECTIVE

The objective of the study was to identify a new nBsAb against thyroid peroxidase (TPO) and thyroglobulin (Tg) in HT patients and to preliminarily explore its immunomodulatory role.

DESIGN, SETTING, AND PATIENTS

Serum samples were obtained from 136 HT patients, 92 diseased controls, and 99 healthy controls for anti-TPO/Tg nBsAb detection. The relationship between anti-TPO/Tg nBsAb and other clinical parameters was also analyzed.

MAIN OUTCOME MEASURES

The anti-TPO/Tg nBsAb was detected using a double-antigen sandwich ELISA. Higher nBsAb levels were found to be associated with decreased inflammation in HT patients.

RESULTS

The prevalence of anti-TPO/Tg nBsAb in HT was 44.9% (61 of 136), significantly higher than that of diseased controls (2.2%, 2 of 92) (P < .0001) and healthy controls (0%, 0 of 99) (P < .0001). HT patients who were nBsAb positive were prone to have significantly lower levels of serum C-reactive protein and TNF-α compared with the nBsAb-negative individuals (P < .05). The serum amyloid A and interferon-γ levels also showed a similar trend in the two groups. The IgG subclass of anti-TPO/Tg nBsAb was IgG4. Further analysis showed a negative correlation between anti-TPO/Tg nBsAb and serum total IgG4 (r = -0.697, P = .025) in IgG4 thyroiditis patients.

CONCLUSIONS

A new type of nBsAb against TPO and Tg in HT patients is identified. Our data also indicate a protective effect of anti-TPO/Tg nBsAb in the pathogenesis of HT and extend prior knowledge about nBsAb in diseases.

Isolation and structural identification of glycopolymers of Bifidobacterium bifidum BIM B-733D as putative players in pathogenesis of autoimmune thyroid diseases

Bifidobacterium bifidum 791 (commercially available as B. bifidum BIM B-733D) cell-surface biopolymers (BPs) interact selectively with human serum thyroid peroxidase (TPO) and thyroglobulin (Tg) autoantibodies (anti TPO and anti Tg, respectively). BPanti-TPO and BPanti-Tg were isolated from the soluble fraction of B. bifidum BIM B-733D by affinity chromatography with anti-TPO or anti-Tg, respectively. Homogeneity of affinity eluates (AEanti-TPO and AEanti-Tg) was tested by size exclusion chromatography. For each AE, the elution profiles generated on the basis of absorbance at 280 nm do not conform to ELISA data for functional activity characteristic of BPs. Moreover, high functional activity was detected in chromatographic fractions that had significantly different molecular weights and no absorbance at 280 nm, which suggests a non-protein (carbohydrate) nature of BPanti-TPO and BPanti-Tg. The semi-preparative size exclusion chromatography of AEanti-TPO and AEanti-Tg with detection by refractometer gave 5,000-7,000 Da fractions containing substances that interact selectively with either anti TPO (BPanti-TPO) or anti-Tg (BPanti-Tg) according to ELISA data. Analysis by two-dimensional NMR spectroscopy including a 1H, 13C-heteronuclear single-quantum coherence experiment indicated that both substances are linear α-1,6-glucans. For the first time, an immunological similarity (molecular mimicry) of glycopolymers of B. bifidum BIM B-733D and human thyroid proteins, TPO and Tg, was shown. On the whole, our data point to a possible role of bifidobacteria in the pathogenesis of autoimmune thyroid diseases (ATD). The main requirements for triggering/acceleration or prevention/abrogation of ATD by bifidobacteria through molecular mimicry mechanism are hypothesised to be (1) genetic predisposition to ATD and (2) intestinal epithelium penetration by α-1,6-glucan.

Correlation and presentation of thyroid functional status with thyroid autoantibodies in long-term follow-up of autoimmune thyroiditis: A study of 116 cases

BACKGROUND/PURPOSE

The most common diagnostic finding of autoimmune thyroid disease (AITD) is the presence of antithyroid antibodies. While autoimmune thyroiditis (AT) is a common AITD, aspiration cytology is one of the important diagnostic tools of AT.

METHODS

We evaluated 116 AT patients with ultrasound-guided aspiration cytology and then analyzed the correlation between thyroid hormone status and thyroid autoantibodies. This was a retrospective analysis with prospective collection of data with a mean follow-up period of 68.8 ± 37.8 months. The patients were classified as either euthyroid, hypothyroid, or hyperthyroid (HT). Of the 116 patients, 22 were hypothyroid, 37 were euthyroid, and 57 were HT.

RESULTS

During the follow-up period, 95.5% of the hypothyroid group remained hypothyroid and only one patient improved to euthyroid. In the euthyroid group, 16.2% progressed to hypothyroid and 83.8% remained euthyroid. In the HT group, 8.7% progressed to hypothyroid, 70.2% progressed to euthyroid, and 21.1% remained HT. Most patients with a high titer of thyroglobulin antibody (TgAb) will progress to hypothyroid, and patients with a high titer of thyroid stimulating hormone (TSH) receptor antibody (TRAb) will remain HT. Strong correlations between thyroid functional status and positive number of thyroid autoantibodies were seen in this study. Patients with all the three antibodies positive had a high prevalence of hyperthyroidism.

CONCLUSION

In our study, most patients were HT; this may be because of the early diagnosis and treatment of AT in our clinic. Although antithyroperoxidase antibody (TPOAb) is a hallmark antibody of HT, it cannot predict the initial presentation and clinical outcome.

Epitope recognition patterns of thyroglobulin antibody in sera from patients with Hashimoto's thyroiditis on different thyroid functional status

Thyroglobulin antibody (TgAb) is a diagnostic serological marker of Hashimoto's thyroiditis (HT). The pathogenesis of HT progression from euthyroidism to hypothyroidism is still not clear. Epitope recognition patterns of TgAb have been shown to be different in individuals who are euthyroid or who have clinical disease. The aim of our study was to investigate the role of thyroglobulin (Tg) epitope specificities in HT progression. Sera from 107 patients with newly diagnosed HT were collected and divided into three groups: patients with hypothyroidism (H, n = 39), subclinical hypothyroidism (sH, n = 31) and euthyroidism (Eu, n = 37). A panel of Tg murine monoclonal antibodies (mAb: PB2, 5E6, 1D4, 5F9, Tg6) and a hircine pAb (N15) were employed as the probe antibodies to define the antigenic determinants recognized by HT sera on competitive enzyme-linked immunosorbent assays (ELISAs). Eight of 39 sera samples in H and seven of 31 in sH inhibited PB2 binding, respectively, whereas none did in Eu. The ratio of sera samples, inhibiting PB2 binding in Eu, was significantly lower than that in H (P = 0.011) and in sH (P = 0.008). For N15, five of 39 sera samples in H, six of 31 in sH and 15 of 37 in Eu inhibited its binding, respectively. The ratio of sera samples, inhibiting N15 binding in Eu, was significantly higher than that in H (P = 0.013). Our study demonstrated that HT patients in different thyroid functional status exhibited different Tg epitope recognition patterns. Epitope patterns of TgAb might be used as a prediction marker of HT progression.