Absence of cross-reactivity to myeloperoxidase of anti-thyroid microsomal antibodies in patients with autoimmune thyroid diseases

Thyroid gland and brain: Enigma of Hashimoto's encephalopathy

The versatile clinical manifestations of the Hashimoto's chronic autoimmune thyroiditis often include psycho-neurological disorders. Although hypothyroidism disturbs significantly the ontogenesis and functions of central nervous system, causing in severe cases of myxedema profound impairment of cognitive abilities and even psychosis, the behavioral, motor and other psychoneurological disorders accompany euthyroid and slightly hypothyroid cases and periods of Hashimoto's disease as well, thus constituting the picture of so called "Hashimoto's encephalopathy". The entity, although discussed and explored for more than 50 years since its initial descriptions, remains an enigma of thyroidology and psychiatry, because its etiology and pathogenesis are obscure. The paper describes the development of current views on the role of thyroid in ontogeny and functions of brain, as well as classical and newest ideas on the etiology and pathogenesis of Hashimot's encephalopathy. The synopsis of the world case reports and research literature on this disorder is added with authors' own results obtained by study of 17 cases of Hashimoto's thyroiditis with schizophrenia-like clinical manifestations. The relation of the disease to adjuvant-like etiological factors is discussed. Three major mechanistic concepts of Hashimoto's encephalopathy are detailed, namely cerebral vasculitis theory, hormone dysregulation theory and concept, explaining the disease via direct action of the autoantibodies against various thyroid (thyroperoxidase, thyroglobulin, and TSH-receptor) and several extrathyroid antigens (alpha-enolase and other enzymes, gangliosides and MOG-protein, onconeuronal antigens) - all of them expressed in the brain. The article demonstrates that all above mentioned concepts intermingle and prone to unification, suggesting the unified scheme of pathogenesis for the Hashimoto's encephalopathy. The clinical manifestations, criteria, forms, course, treatment and prognosis of Hashimoto's encephalopathy and its comorbidity to other diseases - are also discussed in brief. The relation between Hashimoto's encephalopathy and non-vasculitis autoimmune encephalomyelitides of paraneoplastic and non-paraneoplastic origin is emphasized [1 figure, bibliography - 200 references].

Increased Prevalence of Thyroid Disease in Patients with Antineutrophil Cytoplasmic Antibodies–associated Vasculitis

Objective.

Antineutrophil cytoplasmic antibodies (ANCA)–associated vasculitis (AAV) has been linked with thyroid disease as a result of antithyroid medications. We assessed the prevalence of thyroid disease in our patients with AAV.

Methods.

Clinical records of 279 patients with AAV diagnosed between 1991 and 2014 were analyzed.

Results.

Thyroid disease was identified in 21.5% of patients, but only 2 had previously received propylthiouracil. There was a greater proportion of female patients, patients with antimyeloperoxidase antibodies, and patients with renal disease in the group with thyroid disease.

Conclusion.

Our data show a higher prevalence of thyroid disease in patients with AAV than the general population. This was not attributable to antithyroid drugs.

Thyroid Autoimmunity: Role of Anti-thyroid Antibodies in Thyroid and Extra-Thyroidal Diseases

Autoimmune diseases have a high prevalence in the population, and autoimmune thyroid disease (AITD) is one of the most common representatives. Thyroid autoantibodies are not only frequently detected in patients with AITD but also in subjects without manifest thyroid dysfunction. The high prevalence raises questions regarding a potential role in extra-thyroidal diseases. This review summarizes the etiology and mechanism of AITD and addresses prevalence of antibodies against thyroid peroxidase, thyroid-stimulating hormone receptor (TSHR), and anti-thyroglobulin and their action outside the thyroid. The main issues limiting the reliability of the conclusions drawn here include problems with different specificities and sensitivities of the antibody detection assays employed, as well as potential confounding effects of altered thyroid hormone levels, and lack of prospective studies. In addition to the well-known effects of TSHR antibodies on fibroblasts in Graves' disease (GD), studies speculate on a role of anti-thyroid antibodies in cancer. All antibodies may have a tumor-promoting role in breast cancer carcinogenesis despite anti-thyroid peroxidase antibodies having a positive prognostic effect in patients with overt disease. Cross-reactivity with lactoperoxidase leading to induction of chronic inflammation might promote breast cancer, while anti-thyroid antibodies in manifest breast cancer might be an indication for a more active immune system. A better general health condition in older women with anti-thyroid peroxidase antibodies might support this hypothesis. The different actions of the anti-thyroid antibodies correspond to differences in cellular location of the antigens, titers of the circulating antibodies, duration of antibody exposure, and immunological mechanisms in GD and Hashimoto's thyroiditis.

Prevalence of thyroid autoimmunity and dysfunction in women with iron deficiency during early pregnancy: is it altered?

OBJECTIVE

Thyroid disorders and iron deficiency (ID) are associated with obstetrical and fetal complications. Iron is essential for the normal functioning of thyroid peroxidase (TPO-abs) and ID is frequent during pregnancy. The aim of this study was to compare the prevalence of thyroid autoimmunity (TAI) and dysfunction during the first trimester of pregnancy in women with and without ID.

DESIGN

Cross-sectional data analysis of 1900 pregnant women nested within an ongoing prospective collection of pregnant women's data.

METHOD

The study was performed in a single, tertiary referral center. During the first antenatal visit, ferritin, TPO-abs, thyroid-stimulating hormone (TSH) and free T4 (FT4) were measured and age and BMI were recorded. ID was defined as ferritin <15µg/L, TAI when TPO-abs was >60kIU/L, and subclinical hypothyroidism (SCH) when TSH was >2.5mIU/L.

RESULTS

ID was present in 35% of women. Age and BMI were comparable between both groups. In the ID group, the prevalence of TAI and SCH was significantly higher, compared with that in the non-ID group (10% vs 6% and 20% vs 16%; P=0.011 and 0.049 respectively). Ferritin was inversely correlated with serum TSH (ρ=-0.076; P=0.001) and positive with FT4 levels (ρ=0.112; P<0.001). In the logistic regression model, ID remained associated with TAI after correction for confounding factors (P=0.017). The association with SCH was absent after correction for the confounders in the logistic regression model (P=0.082), but remained present in the linear regression model (P=0.035).

CONCLUSIONS

ID was frequent during the first trimester of pregnancy and was associated with a higher prevalence of TAI, higher serum TSH, and lower FT4 levels.

Atypical p-ANCA is not a poor prognostic marker in Postinfectious Glomerulonephritis

Postinfectious glomerulonephritis (PIGN) most commonly follows streptococcal infection. Antineutrophil cytoplasmic antibodies (ANCA) are characteristically negative in PIGN. We report on five cases who had positive atypical pANCA at presentation. The outcome was typical of other cases of PIGN with complete resolution of the glomerulonephritis in all five patients. Atypical pANCA occurs in a number of inflammatory conditions and antigenic targets may include proteins other than myeloperoxidase or proteinase 3. The presence of atypical p-ANCA does not indicate a poor prognosis.

The onset of Graves’ disease during the clinical course of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-associated glomerulonephritis

A 47-year old man presented with atrial fibrillation, weight loss, hand tremor, and hyperperspiration concurrent with the reactivation of the disease activity of myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA)-associated glomerulonephritis. Laboratory findings indicated that the hyperthyroidism had already existed when glomerulonephritis was detected, and Graves' disease became evident while decreasing the dose of prednisolone. Although the levels of thyroid-stimulating hormone receptor antibody, antithyroid peroxidase antibody, and myeloperoxidase antibody increased, both disease activities were suppressed by increasing the dose of prednisolone. This case indicates that MPO-ANCA-associated glomerulonephritis and Graves' disease may share a common pathogenesis.

Antineutrophil cytoplasmic antibody (ANCA)-associated autoimmune diseases induced by antithyroid drugs: comparison with idiopathic ANCA vasculitides

Clinical and serological profiles of idiopathic and drug-induced autoimmune diseases can be very similar. We compared data from idiopathic and antithyroid drug (ATD)-induced antineutrophil cytoplasmic antibody (ANCA)-positive patients. From 1993 to 2003, 2474 patients were tested for ANCA in the Laboratory for Allergy and Clinical Immunology in Belgrade. Out of 2474 patients, 72 (2.9%) were anti-proteinase 3 (PR3)- or anti-myeloperoxidase (MPO)-positive and their clinical and serological data were analyzed. The first group consisted of ANCA-associated idiopathic systemic vasculitis (ISV) diagnosed in 56/72 patients: 29 Wegener's granulomatosis (WG), 23 microscopic polyangiitis (MPA) and four Churg-Strauss syndrome. The second group consisted of 16/72 patients who became ANCA-positive during ATD therapy (12 receiving propylthiouracil and four receiving methimazole). We determined ANCA and antinuclear (ANA) antibodies by indirect immunofluorescence; PR3-ANCA, MPO-ANCA, anticardiolipin (aCL) and antihistone antibodies (AHA) by ELISA; and cryoglobulins by precipitation. Complement components C3 and C4, alpha-1 antitrypsin (α1 AT) and C reactive protein (CR-P) were measured by nephelometry. Renal lesions were present in 3/16 (18.8%) ATD-treated patients and in 42/56 (75%) ISV patients (p <0.001). Skin lesions occurred in 10/16 (62.5%) ATD-treated patients and 14/56 (25%) ISV patients (p <0.01). ATD-treated patients more frequently had MPO-ANCA, ANA, AHA, aCL, cryoglobulins and low C4 (p <0.01). ISV patients more frequently had low α1 AT (p = 0.059) and high CR-P (p <0.001). Of 16 ATD-treated patients, four had drug-induced ANCA vasculitis (three MPA and one WG), while 12 had lupus-like disease (LLD). Of 56 ISV patients, 13 died and eight developed terminal renal failure (TRF). There was no lethality in the ATD-treated group, but 1/16 with methimazole-induced MPA developed pulmonary-renal syndrome with progression to TRF. ANCA-positive ISV had a more severe course in comparison with ATD-induced ANCA-positive diseases. Clinically and serologically ANCA-positive ATD-treated patients can be divided into two groups: the first consisting of patients with drug-induced WG or MPA which resemble ISV and the second consisting of patients with LLD. Different serological profiles could help in the differential diagnosis and adequate therapeutic approach to ANCA-positive ATD-treated patients with symptoms of systemic disease.

Vasculites pulmonares: novas visões de uma velha conhecida

A vasculite necrosante foi descrita em 1866 e seu espectro é muito amplo, uma vez que acomete vasos arteriais e venosos de todos os calibres e de vários órgãos, apresenta diversos tipos de infiltrados inflamatórios, tem um significante número de manifestações clínicas e pode ter ou não fatores desencadeantes identificáveis. A sempre controversa classificação das vasculites mudou radicalmente com a descoberta dos anticorpos anticitoplasma de neutrófilos em 1982, contemplando atualmente a doença de Goodpasture, as vasculites associadas aos anticorpos anticitoplasma de neutrófilos, as vasculites por imunocomplexos e outros tipos de vasculites. As evidências de que os anticorpos anticitoplasma de neutrófilos estão envolvidos na patogênese destas lesões trouxeram avanços consideráveis para o seu diagnóstico e tratamento. Granulomatose de Wegener, doença de Churg-Strauss e poliangeíte microscópica, todas vasculites associadas aos anticorpos anticitoplasma de neutrófilos, são as vasculites sistêmicas que mais acometem os pulmões. Suas manifestações clínicas comuns são tosse, hemorragia alveolar difusa ou asma de difícil controle. Na arterite de Takayasu, na doença de Behçet, na púrpura de Henoch-Schönlein e nas vasculites associadas às doenças do colágeno o acometimento pulmonar é mais raro. Em todos os casos há evidências de serem processos de origem imunológica e com base neste princípio são propostas as abordagens terapêuticas.

Occurrence of antineutrophil cytoplasmic antibodies and associated vasculitis in patients with hyperthyroidism treated with antithyroid drugs: A long-term followup study

OBJECTIVE

To test whether antineutrophil cytoplasmic antibodies (ANCA) and ANCA-associated vasculitis (AAV) are not only induced during treatment with antithyroid drugs, but can also become evident when medication has been ceased, possibly after years.

METHODS

Patients who visited our hospital for the treatment of hyperthyroidism were included (n = 207). Treatment consisted of antithyroid medications, radioactive iodide, thyroidectomy, or a combination of these treatment options. Patients were retested 3-6 years later to evaluate long-term effects of antithyroid drugs. Patients were tested for the presence of ANCA and, if positive, evaluated for the presence of AAV.

RESULTS

Of 209 patients with hyperthyroidism, 12 patients (6%) were positive for myeloperoxidase- (MPO-), proteinase 3-, or human leukocyte elastase-ANCA. Seventy-seven of 209 patients were retested; 1 patient who had not been treated with antithyroid drugs had developed MPO-ANCA. In 3 of 6 patients previously positive, ANCA could still be detected. The presence of ANCA was highly associated with treatment with antithyroid drugs (odds ratio 11.8 [95% confidence interval 1.5-93.3]). Of 13 patients with a positive ANCA result on enzyme-linked immunosorbent assay, AAV with glomerulonephritis was diagnosed in 4 (31%).

CONCLUSION

The presence of ANCA with or without vasculitis is associated with previous treatment with antithyroid drugs, possibly after years.

New findings in pathogenesis of antineutrophil cytoplasm antibody-associated vasculitis

There has been a profusion of studies related to the pathogenesis of antineutrophil cytoplasm antibody-associated small vessel vasculitis. Further definition of epitopes on the major antigens, proteinase-3 and myeloperoxidase, has been sought, and intracellular signal transduction pathways after antineutrophil cytoplasm antibody-neutrophil interactions are beginning to be explored. Antineutrophil cytoplasm antibody stimulation of neutrophils has highlighted the functional importance of the accelerated death that follows the initial activation. The consequences of neutrophil and monocyte activation for endothelium and tissue damage continue to point toward an inflammatory process that has become dysregulated. Factors that initiate vasculitis are being identified slowly. The most secure identifiable environmental trigger is the antithyroid drug propylthiouracil. It is likely that environmental factors operate against a background genetic susceptibility, and polymorphisms in genes for proteins associated with inflammation are being tested for possible links with small vessel vasculitides.