Elevated prolactin to cortisol ratio and polyclonal autoimmune activation in Hashimoto's thyroiditis.

Cortisol and prolactin, which are considered to have an immunomodulatory effect, and selected autoantibodies were determined in Hashimoto's thyroiditis. 37 patients (8 males and 29 females) (54 +/- 13.8 years) and an equal number of sex- and age-matched normal subjects (52.6 +/- 14.2 years) were studied. None of the 74 subjects suffered from any other immunological, infectious, hepatic, renal or malignant diseases. Patients with Hashimoto's thyroiditis exhibited significantly higher (p < 0.016) prolactin values (14.0 +/- 3.8 ng/ml) than did control subjects (6.5 +/- 1.3 ng/ml). In contrast, cortisol levels were lower in Hashimoto's thyroiditis (13.5 +/- 3.2 microg/dl) vs. normal state (16.0 +/- 1.13 microg/dl), (p < 0.05). The prevalence of anti-TPO and anti-Tg antibodies was 100 % and 43 % in the patients with Hashimoto's disease. In contrast, no subject of the control group was positive for anti-TPO, although 9 subjects (24 %) were positive for anti-Tg autoantibodies. The percentage of positive autoantibodies to nucleus, smooth-muscle, and parietal cells in the patients (36.0, 10.9 and 18.5 %, respectively) was higher than that in healthy group (11.0 and 0 % respectively). Notably, neither group was positive for antibodies against double-stranded DNA or mitochondria. In conclusion, our results provide evidence for a polyclonal activity in Hashimoto's thyroiditis, an organ-specific autoimmune disease, associated with an altered prolactin-adrenocortical status. Such information should initiate longitudinal studies to clarify the exact time sequence of these events related to the disease's activity.     

Thyroid autoantigens and their relevance in the pathogenesis of thyroid autoimmunity

Humoral and cellular immune responses are both involved in autoimmune disorders of the thyroid gland. In the last five years, new substantial data have been obtained on the nature and the expression of thyroid cell surface autoantigens and on the demonstration of the functional heterogeneity of autoantibodies to the thyroid stimulating hormone (TSH) receptor. In the present report, attention will be mainly focused on recent studies carried out in our laboratory. The main autoantigens so far identified include the 'microsomal' antigen, thyroglobulin and the TSH receptor. For many years the 'microsomal' antigen (M) was considered a poorly characterized constituent of the cytoplasm of the thyroid cell. In the last five years, several lines of evidence were provided indicating that M is also well represented on the surface of the follicular cell and is identical to thyroid peroxidase (TPO). The use of anti-TPO monoclonal antibodies, presently available, have confirmed this antigenic identity. Microsomal (anti-TPO) antibodies are very useful markers of autoimmune thyroid disorders and are generally present in Hashimoto's thyroiditis, idiopathic myxedema and Graves' disease. TSH receptor antibodies (TRAb) are present in the sera of patients with Graves' disease. TRAb are able to stimulate thyroid adenylate cyclase and also to mimic TSH in its thyroid growth stimulation. Thus, these antibodies may have a pathogenetic role in goiter formation and in thyroid hyperfunction in Graves' disease. TRAb were also shown to inhibit both TSH binding to its receptor and TSH-stimulated adenylate cyclase activity. Recently TRAb, which inhibited TSH-stimulated adenylate cyclase activity, were found in idiopathic myxedema patients and may be responsible for impairment of thyroid function.(ABSTRACT TRUNCATED AT 250 WORDS)     

Analysis of Fas, FasL and Caspase-8 expression in thyroid gland in young patients with immune and non-immune thyroid diseases

INTRODUCTION: Apoptosis, programmed cell death is a regulating mechanism enabling the removal of superabundantly produced and unnecessary at the certain moment cells. Disturbances of the apoptosis regulation contribute to the pathogenesis of many diseases, including autoimmune thyroid disorders. The aim of this study was to estimate expression of proapoptotic Fas/FasL and caspase-8 in thyroid tissues in patients with Graves' disease (GD), non-toxic nodular goiter (NTNG) and Hashimoto's thyroiditis (HT). MATERIAL AND METHODS: Inclusion criteria of Graves' patients were: large goiter, ophthalmopathy, TRAb > 5 U/L, positive titre of anti-TPO and anti-TG antibodies and concentration of TSH < 0.45 microIU/mL for more the 2-3 months from an onset of the disease. Isolated thyrocytes were identified by indirect method: in the first stage mouse monoclonal antibodies (mAbs) anti-TPO were bound to rabbit anti-mouse antibodies IgG (Fab')2 labeled FITC. To obtained cellular suspension mAbs directed against apoptotic Fas/FasL molecules labeled with PE (Phycoerythrin) was added. All investigations were performed on Coulter EPICS XL flow cytometer. Detection of apoptotic proteins was confirmed by Western Blot and immunohistochemistry methods using mAbs in DAB chromogene visuality and marked by Mayer's haematoxylin. Evaluation of caspase-8 expression in thyroid follicular cells was performed by Western Blot test. RESULTS: The analysis of Fas and FasL expression on surface of thyroid follicular cells was higher in patients with Hashimoto's thyroiditis (38%, 26%) in comparison with patients with Graves' disease (18%, 14%). In case of patients with Hashimoto's thyroiditis significantly lower percentage of thyroid tissue infiltrating immune Fas+ (13%) and FasL+ (22%) T cells in comparison with Graves' patients (33%, 43% respectively) was observed . Identification of proapoptotic Fas and FasL molecules in the thyroid follicular cells revealed higher expression of both proteins in patients with GD (++,++) and HT (+++; +++, respectively) in comparison with NTNG patients (+/0; +/0). Caspase-8 expression was detected in band 55 kDa using Western Blot test in patients with thyroid autoimmune diseases. CONCLUSIONS: We conclude that alteration in the expression of proapoptotic proteins in thyroid follicular cells may play a role in pathogenesis of thyroid autoimmune disorders. In addition, suppression of apoptosis in Graves' disease led to increased proliferation of thyroid follicular cells which is responsible for goiter formation.     

The thyroid gland function assessment in women after mastectomy and chemotherapy during breast cancer therapy

INTRODUCTION: For many years much attention has been focused on an interaction between the breast disease and the thyroid gland function in the literature. In those studies the question whether disease changes in the thyroid gland can induces the breast disease was addressed. On the other hand there are a few works concerning the inverted question whether the breast cancer therapy, in particular after mastectomy and chemotherapy, can disturb the thyroid gland function. The aim of the study is to investigate the influence of the mastectomy and chemotherapy on the thyroid gland function in women after breast cancer therapy. MATERIAL AND METHODS: 173 patients aged 30-80 (average 56) were included in this study. The studied group comprised 97 women after breast cancer therapy (average age 60). The control group consisted of 76 patients (average age 55). 75 patients after mastectomy of the studied group were additionally treated with chemotherapy, but in 22 women chemotherapy was not applied. The following methods were used to carry out the research: the USG method was applied to evaluate thyroid morphological condition in women after mastectomy and chemotherapy; the color Doppler technique was used for dynamic presentation and fine- needle aspiration biopsy: examination of the thyroid functional state by measuring the TSH, fT(3), fT(4) hormone concentration and the level of antithyroid antibodies. RESULTS: An average concentration of antithyroid antibodies: anti-TPO and anti-Tg was found significantly higher in the studied group of women after chemotherapy, comparing with the control group. The level of fT(3) hormone concentration was comparable in all investigated groups. Nevertheless, the average concentration of TSH was found higher in women after mastectomy and chemotherapy and as a consequence leading to hypothyroidism. CONCLUSION: Taking into consideration the high level of the concentration of antithyroid antibodies: (anti-TPO and anti- Tg), which lead to destruction of the thyroid gland tissue, the thyroid gland function of the women after mastectomy and chemotherapy should be monitored morphologically as well as functionally.     

Anti-GAD-positive patients with type 1 diabetes mellitus have higher prevalence of autoimmune thyroiditis than anti-GAD-negative patients with type 1 and type 2 diabetes mellitus

The aim of our study was to evaluate antibodies against thyroglobulin (anti-TG) and thyroid peroxidase (anti-TPO) - markers of autoimmune thyroiditis - in several groups of adult patients with type 1 and type 2 diabetes mellitus (DM). We were particularly interested whether the presence of thyroid antibodies is related to the positivity of glutamic acid decarboxylase antibodies (anti-GAD). We found elevated anti-GAD in 46 % (97/210) patients with type 1 DM. All patients with type 2 diabetes were anti-GAD-negative. At least one thyroid antibody (anti-TG and/or anti-TPO) was found in 30 % (62/210) patients with type 1 DM and 27 % (22/83) type 2 diabetes patients. The patients with type 1 DM were further grouped according to their anti-GAD status. The anti-GAD-positive patients had a higher prevalence of anti-TG antibodies than the anti-GAD-negative patients (25 % vs. 12 %, p=0.03) as well as anti-TPO antibodies (32 % vs. 12 %, p<0.001). At least one thyroid antibody was detected in 39 % (38/97) of anti-GAD-positive but only in 21 % (24/113) of anti-GAD-negative patients with type 1 DM (p=0.006). No significant difference in the frequency of thyroid antibodies was found between anti-GAD-negative patients with type 1 and type 2 DM (21 % vs. 27 %, p=0.4). The groups with or without thyroid antibodies in both type 1 and type 2 diabetic patients did not differ in actual age, the age at diabetes onset, duration of diabetes, body mass index or HbA1c level. Patients with elevated thyroid antibodies had significantly higher levels of TSH than those without thyroid antibodies (1.86 vs. 3.22 mIU/l, p=0.04 in type 1 DM; 2.06 vs. 4.89 mIU/l, p=0.003 in type 2 DM). We conclude that there is a higher frequency of thyroid-specific antibodies in anti-GAD-positive adult patients with type 1 DM than in anti-GAD-negative patients or in patients with type 2 DM. Patients with or without thyroid antibodies do not differ in age, DM onset and duration, BMI or HbA1c. Thyroid antibodies-positive patients have higher levels of thyroid stimulating hormone (TSH).     

Immunoglobulin G subclasses of anti-thyroid peroxidase autoantibodies in human autoimmune thyroid diseases

A distribution of immunoglobulin G (IgG) subclass of anti-thyroid peroxidase (TPO) autoantibodies was studied to know whether anti-TPO autoantibodies are closely implicated in the pathogenesis of human autoimmune thyroid diseases. As a result of analyzing 14 patients' sera, 7 with Graves' disease and 7 with Hashimoto's thyroiditis, anti-TPO autoantibodies were found to consist of mainly IgG1 subclass. Percentages of both IgG1 and IgG2 subclasses in IgG class of autoantibodies corresponded to those in the normal serum composition, whereas IgG3 subclass was scarcely contained in anti-TPO autoantibodies and IgG4 subclass markedly increased. It was thought that anti-TPO autoantibodies had a capability to lyse thyroid follicular cells by the mechanism of antibody-dependent complement-mediated cytolysis, because IgG1 and IgG2 subclasses of antibodies can fix complement and TPO locates in apical membrane surface of thyroid follicular cells. Comparing Graves' disease with Hashimoto's thyroiditis, mean percentages of both IgG1 and IgG2 subclasses of 2 groups were statistically different. Namely, sera of patients with Graves' disease had higher and lower mean percentages of IgG1 and IgG2 subclasses of autoantibodies, respectively, than those with Hashimoto's thyroiditis, though no plausible explanation for these differences can be offered at the present time.     

Anti-Helicobacter Pylori, anti-thyroid peroxidase, anti-thyroglobulin and anti-gastric parietal cells antibodies in Czech population

Autoimmune thyropathies are frequently linked to many infections, such as Helicobacter pylori, which are also supposed to play a role in their pathogenesis. The aim of this study was to evaluate the relationships between thyroid and gastric autoimmunity and H. pylori infection on a large sample of Czech population (n=1621) by monitoring the autoantibodies against thyroglobulin (anti-Tg) and thyroid peroxidase (anti-TPO) and gastric parietal cell (anti-GPC, representing thyrogastric syndrome) in correlation with antibodies against Helicobacter pylori (anti-H. pylori) of classes IgG and IgA. The interrelation between autoantibodies and H. pylori antibodies was assessed by H. pylori seropositivity. In H. pylori seropositive persons as compared to seronegative irrespective of age and sex, a higher occurrence of anti-TPO (10.4 % vs. 5.8 %, p=0.001) and anti-GPC (6.1 % vs. 1.7 %, p<0.001) was found. Differences in anti-TPO occurrence were significant in both men (7.0 % vs. 3.3 %, p=0.03) and women (12.7 % vs. 8.0 %, p=0.02), differences in anti-GPC occurrence were significant only in women (7.2 % vs. 1.7 %, p<0.001). Results of this study support the idea of a connection between infection of H. pylori and the occurrence of anti-TPO autoantibodies representing thyroid autoimmunity and gastric parietal cells autoantibodies representing the thyrogastric syndrome.     

Urine Selenium Changes During Pregnancy Do Not Correlate with Thyroid Autoantibodies in a Mildly Iodine Deficient Population

Selenium (Se) is a key component of iodinases; higher Se levels are associated with lower titers of antithyroid peroxidase antibodies (anti-TPO). Pregnancy exerts profound effects on thyroid function and autoimmunity. To assess the relationship of urine Se levels with thyroid function and autoimmunity in pregnant women residing in Athens, Greece, we studied prospectively 47 euthyroid women in uncomplicated singleton pregnancies (mean age + SD: 30?+?5 years) in each trimester, measuring urine Se levels, urine iodine, plasma thyrotropin (TSH), free thyroxine and triiodothyronine (FT4 and FT3), as well as levels of anti-TPO antibodies. Changes of the measured parameters were assessed over each trimester; thyroid parameters were assessed with relation to Se levels. Urine Se dropped by the third trimester, whereas urine iodine did not change appreciably during pregnancy. TSH and anti-TPO did not show appreciable changes; FT4 and FT3 gradually decreased as the pregnancy advanced. No relationship between urine Se levels and anti-TPO was found. During pregnancy, changes in urine Se levels accompany mild changes in thyroid function. However, we did not find some association between these changes and thyroid autoimmune activity over this period, probably because the effect of Se on thyroid autoimmunity may only become apparent in case of excess Se fortification.     

Screening for associated autoimmunity in type 1 diabetes mellitus with respect to diabetes control

As an autoimmune disease, type 1 diabetes mellitus (DM) can be associated with other autoimmune disorders. The aim of this study was to detect subclinically associated autoimmune thyroid disease, coeliac disease, and Addison's disease. The presence of autoantibodies was evaluated with special regard to the control of diabetes and to the clinical status of the patient. Fifty-one type 1 diabetic patients (22 men, 29 women, mean age 37+/-11 years, mean duration of diabetes 16+/-13 years) were included into this study. Specific antibodies to islet antigens--glutamic acid decarboxylase (GAD65), protein thyrosine phosphatase IA-2alpha, and to thyroid autoantigens--thyroid microsomal peroxidase (TPO) and thyroglobulin (TG) and also thyroid stimulating hormone (TSH) were measured by RIA. Autoantigens of the small intestine--tissue transglutaminase autoantibodies (ATTG), IgA and IgG antibodies to gliadin (AGA-IgA, AGA-IgG) were evaluated by ELISA. Endomysial autoantibodies (EMA) and adrenal cortex antibodies (ACA) were detected by indirect immunofluorescence microscopy. Eleven new cases of thyreopathy (22 % of patients) were detected by the assessment of thyroid autoantibodies and TSH. Two new cases of thyreotoxicosis were diagnosed during the study. Coeliac disease was diagnosed in at least two cases. Addison's disease was not diagnosed, although the ACA were positive in two patients. No influence of single or combined autoantibody positivity on the control of diabetes was found if normal organ function was preserved. In both patients with thyreotoxicosis the control of diabetes was worsened and improved after treatment. The screening of autoantibodies in type 1 diabetic patients could reveal subclinical cases of AITD or coeliac disease. Subclinical forms of these disorders have no influence on diabetes control. However, impaired organ function may be associated with the worsened control of diabetes as we demonstrated on two newly diagnosed cases of thyreotoxicosis. We suggest the need for the follow-up of patients with positive autoantibodies because further deterioration of the respective organs can be expected.     

Human thyroid peroxidase: mapping of autoantibodies, conformational epitopes to the enzyme surface

The enzyme, thyroid peroxidase (TPO), is a dominant antigen in thyroid autoimmune diseases. Autoantibodies recognised two major dominant conformational epitopes termed A and B. The epitopes have been defined by mAbs, but the amino acid residues which constitute these determinants remain unknown. Using a model of TPO, built from the structure of myeloperoxidase (MPO), we have synthesised peptides corresponding to exposed loops and generated rabbit antibodies to the peptides. Antisera to peptide sequence 599-617 (peptide 14) representing a highly protrusive loop on the TPO, showed the highest inhibition in 65 sera from patients positive with anti-TPO antibodies. The inhibition was by 15-80% (mean 41%), and no other antibody showed any inhibition. Binding of hFabs to the B determinant on TPO was inhibited by anti-peptide 14 antibodies more then 85%, but not Fabs to the A determinant. In conclusion, the peptide 14 defines a sequence taking part in building up the B major conformational epitope. None of generated anti-peptide antibodies alone inhibited the binding of human Fabs to the A epitope, however a combination of four anti-peptide antibodies (P1, P12, P14 and P18) inhibits Fabs binding to the A determinant by more then 60% and autoantibodies binding from 65% to 94%. Combination of antibodies reacting with peptides outside the surface defined by those four antipeptide antibodies did not give any inhibition of Fabs to TPO. The inhibition of Fabs and auto Abs to TPO by this combination of anti-peptide Abs is the result of steric hindrance as none of these Abs individually inhibited auto Abs' or Fabs' binding to TPO. The four peptides define an area on the enzyme surface where the A and B major conformational epitopes are localised.     

Assessing the Relationship Between Serum Ghrelin Levels and Metabolic Parameters and Autoimmunity in Patients with Euthyroid Hashimoto's Thyroiditis

ObjectivesHashimoto’s thyroiditis (HT) may affect metabolic parameters and increase predisposition to obesity. In this study, we aimed to assess the relationships among serum ghrelin concentrations, metabolic parameters, and thyroid autoimmunity in euthyroid HT patients.MethodsThe study included 48 euthyroid HT patients and 41 age- and sex-matched healthy controls. We assessed serum ghrelin, free triiodothyronine (T3), free thyroxine (T4), thyroid-stimulating hormone (TSH), thyroid peroxidase antibody (anti-TPO), thyroglobulin antibody (anti-Tg), fasting blood glucose (FBG), insulin, lipid levels, and homeostasis model assessment insulin resistance (HOMA-IR) in all subjects.ResultsSex distribution, mean age, and body mass index (BMI) were similar in HT patients and controls (female/male, 42/6 vs. 33/8, 46.8 ± 14.7 vs. 45 ± 12.5 years,28.5 ± 6.1 vs. 28.4 ± 4.9 kg/m², respectively; P>.05 for all). The mean waist circumference (WC) of the HT group was significantly higher than that of the control group (100.6 ± 14.6 vs. 93.2 ± 13.2 cm, P = .015). While FBG, low-density lipoprotein cholesterol (LDL-C), and triglyceride levels in the HT group were significantly higher than in the control group, insulin levels and HOMA-IR were similar. Ghrelin levels were lower in HT patients compared to controls (416.9 ± 224.4 and 689.9 ± 191.6 pg/mL, respectively; P<.001). Ghrelin levels were similar in patients with low and high anti-TPO titers. Negative correlations were observed between ghrelin levels and BMI, WC, and anti-TPO levels. Regression analysis revealed that HT was the most important predictor of ghrelin levels.ConclusionEuthyroid HT is associated with a decrease in plasma ghrelin levels. Altered body fat distribution and increased anti-TPO levels do not seem to be directly involved in lower ghrelin levels in euthyroid HT patients.     

Anti-thyroglobulin anti-idiotypic antibodies in sera of patients with Hashimoto's thyroiditis and Graves' disease

The objective of this study was to find naturally occurring anti-idiotypic (anti-Id) antibodies to anti-human thyroglobulin (anti-hTg) idiotype in sera of patients with autoimmune thyroid disease. Sera from patients with Hashimoto's thyroiditis (HT), Graves' disease (GD), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE) and sera from normal subjects were tested for the presence of anti-Id antibodies against mouse anti-hTg monoclonal antibodies (McAb) in indirect ELISA and in indirect solid-phase RIA. Microtitration plates were coated with six McAb, five of them directed against different epitopes on hTg molecule, and then incubated with patients' sera. The bound antibody was detected with either peroxidase or 125I-labeled anti-human IgG. The specific positive reaction was observed in four of 40 patients with HT, in two of 26 patients with GD, in seven of 58 patients with RA, and in none of 20 normal subjects. The detected binding was due to the presence of anti-hTg anti-Id antibodies and not to Tg-anti-Tg circulating immune complexes, as the positive sera did not contain hTg when resolved on SDS-PAGE, nor did they bind to all anti-hTg McAb tested. The binding was dose dependent, and titers of anti-Id antibodies varied from 1:243 to 1:2187. The binding could be inhibited up to 50% by hTg, but not by the thyroid microsomal antigen, indicating that some of those anti-Id might represent the internal image of the antigen. Serum from the patient 3403, showing the strongest reactivity against McAb A-3, was chosen for IgG purification and F(ab')2 fragment isolation. The 3403 F(ab')2 fragment, but not the Fc fragment, was found to react specifically with four mouse anti-hTg McAb but not with the control mouse IgG. Thus, the obtained results permit the conclusion that anti-hTg anti-Id antibodies could occur naturally during the course of thyroid autoimmune disorders.     

Human thyroid peroxidase: mapping of autoantibodies,conformational epitopes to the enzyme surface

Abstract

The enzyme, thyroid peroxidase (TPO), is a dominant antigen in thyroid autoimmune diseases. Autoantibodies recognised two major dominant conformational epitopes termed A and B. The epitopes have been defined by mAbs, but the amino acid residues which constitute these determinants remain unknown. Using a model of TPO, built from the structure of myeloperoxidase (MPO), we have synthesised peptides corresponding to exposed loops and generated rabbit antibodies to the peptides.

Antisera to peptide sequence 599–617 (peptide 14) representing a highly protrusive loop on the TPO, showed the highest inhibition in 65 sera from patients positive with anti-TPO antibodies. The inhibition was by 15–80% (mean 41%), and no other antibody showed any inhibition. Binding of hFabs to the B determinant on TPO was inhibited by anti-peptide 14 antibodies more then 85%, but not Fabs to the A determinant. In conclusion, the peptide 14 defines a sequence taking part in building up the B major conformational epitope.

None of generated anti-peptide antibodies alone inhibited the binding of human Fabs to the A epitope, however a combination of four anti-peptide antibodies (P1, P12, P14 and P18) inhibits Fabs binding to the A determinant by more then 60% and autoantibodies binding from 65% to 94%. Combination of antibodies reacting with peptides outside the surface defined by those four anti-peptide antibodies did not give any inhibition of Fabs to TPO.

The inhibition of Fabs and auto Abs to TPO by this combination of anti-peptide Abs is the result of steric hindrance as none of these Abs individually inhibited auto Abs' or Fabs' binding to TPO.

The four peptides define an area on the enzyme surface where the A and B major conformational epitopes are localised.     

Postpartum thyroid dysfunction in Mid Glamorgan

A high prevalence of postpartum thyroid dysfunction has been reported in several countries, but there have been no systematic studies of its prevalence in Britain. Among a group of 901 consecutive, unselected pregnant women thyroid autoantibodies were detected in 117 (13%) at booking. The clinical course of postpartum thyroid dysfunction, factors associated with its development, and its likely prevalence were defined in 100 of these women with thyroid antibodies and 120 women with no such antibodies who were matched for age. None of the women had a history of autoimmune thyroid disease. Normal reference ranges for thyroid function during pregnancy and post partum were established in the 120 women negative for thyroid antibodies. On the basis of these observations postpartum thyroid dysfunction was observed in 49 (22%) of the 220 women studied, and the prevalence in the total group of 901 women was estimated to be 16·7%. Thyroid dysfunction, mainly occurring in the first six months post partum, was usually transient and included both destruction induced hyperthyroidism and hypothyroidism. The development of the syndrome was significantly related to smoking more than 20 cigarettes a day and the presence of thyroid microsomal autoantibodies at booking. Of the 16 women with a family history of thyroid disease in whom thyroid microsomal autoantibody activity was detectable at booking, 11 developed thyroid dysfunction. Age, parity, presence of goitre at presentation, duration of breast feeding, and the sex and birth weight of the infant were not associated with the development of postpartum thyroid dysfunction.The mood changes experienced by women post partum may in part be associated with altered thyroid function during this time.     

Interferon-induced thyroiditis during treatment of chronic hepatitis C

Thyroid function disorders affect between 5% and 15% of patients treated with IFNα and RBV for chronic hepatitis C. Women and patients with thyroid peroxidase antibodies (TPOAb) found before the treatment are at risk of developing the disorders (46.1% vs. 5.4%). The spectrum of IFNα-induced thyroiditis (IIT) includes two groups. Disorders with an autoimmune background are: presence of thyroid autoantibodies without clinical disease, Hashimoto's disease and Graves' disease. The second group comprises diseases caused by the direct toxic effect of IFNα on the thyroid gland, i.e. destructive thyroiditis and non-autoimmune hypothyroidism. Thyroid diseases are not an absolute contraindication for IFNα and RBV therapy. In patients diagnosed with thyroid dysfunction, before the antiviral therapy it is necessary to achieve euthyreosis. Thyroid function disorders may occur at any moment of the therapy. The earliest have been observed in the 4th week of treatment, and the latest 12 months after its termination. During the therapy, in order to diagnose IIT early, it is recommended to determine TSH level every 2-3 months depending on the presence of TPOAb before the treatment. The diagnosis and treatment of thyroid function disorders should be conducted in co-operation with an endocrinologist.     

Mapping of a linear autoantigenic epitope within the human thyroid peroxidase using recombinant DNA techniques.

Autoantibodies directed against the thyroid peroxidase (TPO), the thyroid microsomal antigen, are widely used to diagnose human autoimmune thyroid disease. A cloned 3.088 kb cDNA coding for the entire mature human TPO was isolated from a cDNA library derived from a pathological thyroid gland of a Graves' disease patient and used further to generate a so-called TPO epitope cDNA library in order to map linear autoantigenic epitopes involving a recombinant molecular biology approach. The TPO epitope cDNA library consisting of randomly fragmented cDNA sequences inserted in the expression vector pGEX-2T was expressed in Escherichia coli and screened with characterized anti-TPO autoantisera from Hashimoto's disease patients. All the sera were positively tested with a purified thyroid microsomal antigen fraction (TMA/TPO). Only about 1% of examined autoantisera were able to recognize bacterial expressed recombinant TPO representing sequential antigenic determinants. A corresponding autoantigenic epitope with 61 amino acids in length was located at the C-terminus of human TPO.     

Human anti-thyroid peroxidase single-chain fragment variable of Ig isolated from a combinatorial library assembled in-cell: insights into the in vivo situation

In an attempt to explore the natural variable heavy and light chain (VH/VL) pairing of autoantibodies involved in Graves' disease, we constructed a phage-displayed Ab library obtained by in-cell PCR of thyroid-infiltrating cells. We report here the molecular cloning and characterization of human single-chain fragment variable regions (scFv) specific for thyroid peroxidase (TPO) generated from this library. On the basis of the nucleotide sequences, three different scFvs were obtained (ICA1, ICB7, and ICA5). All were encoded by genes derived from the VH1 and Vlambda1 gene families. Using BIACORE for epitope mapping and kinetic analysis, we showed that these scFvs exhibited high affinity (Kd = 1 nM) for TPO and recognized three different epitopes. The biological relevance of these scFvs as compared with serum anti-TPO autoantibodies was assessed by competition studies. Sera from all the 29 Graves' disease patients tested were able to strongly inhibit (60-100%) the binding of the 3 scFvs to TPO. These data demonstrate that the in-cell PCR library generated human anti-TPO scFvs that retained the VH/VL pairing found in vivo and that the different epitope specificities defined by these scFvs overlapped with those found in the sera of patients with autoimmune thyroid disease.     

Long COVID in Patients With Mild to Moderate Disease: Do Thyroid Function and Autoimmunity Play a Role?

ObjectivePost-acute sequelae of coronavirus disease 2019 (COVID-19) or long COVID (LC) is an emerging global health issue. Fatigue is a common feature. Whether thyroid function and autoimmunity play a role is uncertain. We aimed to evaluate the prevalence and predictors of LC and the potential role of thyroid function and autoimmunity in LC.MethodsWe included consecutive adults without a known thyroid disorder who were admitted to a major COVID-19 center for confirmed COVID-19 from July to December 2020. Thyroid function tests and antithyroid antibodies were measured for all patients on admission and at follow-up. LC was defined by the presence or persistence of symptoms upon follow-up.ResultsIn total, 204 patients (median age, 55.0 years; 95 men [46.6%]) were reassessed at a median of 89 days (interquartile range, 69-99) after acute COVID-19. Of the 204 patients, 41 (20.1%) had LC. Female sex (adjusted odds ratio, 2.48; P = .018) and severe acute respiratory syndrome coronavirus 2 polymerase chain reaction cycle threshold value of <25 on admission (adjusted odds ratio, 2.84; P = .012) independently predicted the occurrence of LC. Upon follow-up, most abnormal thyroid function tests in acute COVID-19 resolved, and incident thyroid dysfunction was rare. Nonetheless, we observed incident antithyroid peroxidase (anti-TPO) positivity. Although baseline or follow-up thyroid function tests were not associated with the occurrence of LC, among 172 patients with symptomatic acute COVID-19, symptom resolution was more likely in those with positive anti-TPO upon follow-up (P = .043).ConclusionLC is common among COVID-19 survivors, with females and those with higher viral load in acute COVID-19 particularly being vulnerable. The observation of incident anti-TPO positivity warrants further follow-up for thyroid dysfunction. Whether anti-TPO plays a protective role in LC remains to be elucidated.     

Antigenic relation between thyroid peroxidase and the microsomal antigen implicated in auto-immune diseases of the thyroid

Pools of sera from patients with Graves' disease or Hashimoto's thyroiditis highly inhibit the binding to human thyroid membranes of one of 19 monoclonal antibodies raised against preparations of human thyroid membranes. This monoclonal antibody reacts with human and bovine thyroid peroxidase and bovine lactoperoxidase but not with human hemoglobin, cytochrome c and other related molecules. These results indicate that the thyroid peroxidase and the microsomal antigen are antigenically related. These data taken together with those from other groups, highly suggest that thyroid peroxidase is the microsomal antigen involved in autoimmune thyroid diseases.     

Prediction of domain organisation and secondary structure of thyroid peroxidase, a human autoantigen involved in destructive thyroiditis

Organ specific autoimmune diseases are relatively common immunological disorders in man which include thyroid autoimmune disease, insulin-dependent diabetes mellitus and myasthenia gravis. The target autoantigens in some of these diseases have recently been characterised. In thyroid autoimmune disease this includes the key enzyme, thyroid peroxidase (TPO), which is involved in the generation of thyroid hormone. Structural knowledge about autoantigens such as thyroid peroxidase will allow a greater understanding of the interaction between autoantigens and the aberrant immune response, and facilitate the development of strategies for antigen-specific therapeutic manipulation. We report here a prediction of the secondary structure of thyroid peroxidase, together with the results of circular dichroic spectroscopy of a homologous purified enzyme. A combination of 3 secondary structure prediction programs has been used, following multiple sequence alignment, and TPO has been found to consist mainly of alpha-helical conformation, with little beta-sheet present. This structure prediction, together with knowledge of the exon-intron boundaries allows a model for the domain organisation of the TPO molecule to be proposed.