Thyroid Autoimmunity and Function after Treatment with Biological Antirheumatic Agents in Rheumatoid Arthritis

Polyautoimmunity in Patients With Anticyclic Citrullinated Peptide Antibody-Positive and -Negative Rheumatoid Arthritis: a Nationwide Cohort Study From Denmark

OBJECTIVE

This study aimed to compare the prevalence and incidence of polyautoimmunity between anticyclic citrullinated peptide antibody (anti-CCP)-positive and anti-CCP-negative patients with rheumatoid arthritis (RA).

METHODS

In a nationwide register-based cohort study, patients with RA (disease duration ≤ 2 yrs) in the DANBIO rheumatology register with an available anti-CCP test in the Register of Laboratory Results for Research were identified. The polyautoimmunity outcome included 21 nonrheumatic autoimmune diseases identified by linkage between the Danish Patient Registry and Prescription Registry. The age- and sex-adjusted prevalence ratio (PR) was calculated by modified Poisson regression to estimate the prevalence at diagnosis in anti-CCP-positive vs anti-CCP-negative patients. The hazard ratio (HR) of polyautoimmunity within 5 years of entry into DANBIO was estimated in cause-specific Cox regression models.

RESULTS

The study included 5839 anti-CCP-positive and 3799 anti-CCP-negative patients with RA. At first visit, the prevalence of prespecified polyautoimmune diseases in the Danish registers was 11.1% and 11.9% in anti-CCP-positive and anti-CCP-negative patients, respectively (PR 0.93, 95% CI 0.84-1.05). The most frequent autoimmune diseases were autoimmune thyroid disease, inflammatory bowel disease, and type 1 diabetes mellitus. During a mean follow-up of 3.5 years, only a few (n = 210) patients developed polyautoimmunity (HR 0.6, 95% CI 0.46-0.79).

CONCLUSION

Polyautoimmunity as captured through the Danish National Patient Registry occurred in approximately 1 in 10 patients with RA at time of diagnosis regardless of anti-CCP status. In the years subsequent to the RA diagnosis, only a few and mainly anti-CCP-negative patients developed autoimmune disease.

Disease-modifying antirheumatic drugs and risk of thyroxine-treated autoimmune thyroid disease in patients with rheumatoid arthritis

BACKGROUND

Autoimmune thyroid disease (AITD) and rheumatoid arthritis (RA) share a genetic background, and the prevalence of AITD in RA patients is increased. Whereas immunomodulatory treatments are used in RA, they are rarely used in AITD.

OBJECTIVES

We hypothesized that disease-modifying antirheumatic drugs (DMARDs) as used in RA might lower the risk of incident AITD.

METHODS

A nationwide cohort study including 13,731 patients with new-onset RA from the Swedish Rheumatology Quality Register 2006-2018 and 63,201 matched general population comparators linked to national registers to identify AITD. We estimated relative risks (hazard ratios) of AITD after RA diagnosis in RA patients compared to the general population, and in relation to DMARD treatment, using Cox regression.

RESULTS

Following RA diagnosis, 321 (2.3%) of the RA patients and 1838 (2.9%) of the population comparators developed AITD, corresponding to an incidence of 3.7 versus 4.6 per 1000 person-years, hazard ratio, 0.81; 95% CI, 0.72-0.91. The decreased risk of incident AITD among RA patients compared to the general population was most pronounced among biologic DMARD (bDMARD) treated patients, with a hazard ratio of 0.54; 95% CI, 0.39-0.76. Among RA patients, subgrouped by bDMARD use, TNF-inhibitors were associated with the most pronounced decrease, hazard ratio, 0.67; 95% CI, 0.47-0.96.

CONCLUSIONS

In contrast to the increased prevalence of AITD in RA patients at diagnosis, our results indicate that the risk of AITD decreases following RA diagnosis. This decrease is especially pronounced in RA patients treated with bDMARDs. These findings support the hypothesis that DMARDs might have a preventive effect on AITD.

Myeloid cells interact with a subset of thyrocytes to promote their migration and follicle formation through NF-κB

The pathogenesis of thyroid dysgenesis (TD) is not well understood. Here, using a combination of single-cell RNA and spatial transcriptome sequencing, we identify a subgroup of NF-κB-activated thyrocytes located at the center of thyroid tissues in postnatal mice, which maintained a partially mesenchymal phenotype. These cells actively protruded out of the thyroid primordium and generated new follicles in zebrafish embryos through continuous tracing. Suppressing NF-κB signaling affected thyrocyte migration and follicle formation, leading to a TD-like phenotype in both mice and zebrafish. Interestingly, during thyroid folliculogenesis, myeloid cells played a crucial role in promoting thyrocyte migration by maintaining close contact and secreting TNF-α. We found that cebpa mutant zebrafish, in which all myeloid cells were depleted, exhibited thyrocyte migration defects. Taken together, our results suggest that myeloid-derived TNF-α-induced NF-κB activation plays a critical role in promoting the migration of vertebrate thyrocytes for follicle generation.

Polyautoimmunity in patients with cutaneous lupus erythematosus: A nationwide sex- and age-matched cohort study from Denmark

Background

Polyautoimmunity is defined as having 2 or more autoimmune diseases. Little is known about polyautoimmunity in patients with cutaneous lupus erythematosus (CLE).

Objectives

To estimate prevalence and 5-year incidence of non-lupus erythematosus (LE) autoimmune diseases in patients with CLE.

Methods

Patients with CLE were identified In the Danish National Patient Registry and each patient was age- and sex-matched with 10 general population controls. Outcome information on non-LE autoimmune diseases was obtained by register-linkage between Danish National Patient Registry and the National Prescription Register. The risk ratio (RR) for prevalent non-LE autoimmune disease at time of CLE diagnosis was calculated in modified Poisson regression; and hazard ratios (HRs) for incident non-LE autoimmune disease were estimated in Cox regression analyses.

Results

Overall, 1674 patients with CLE had a higher prevalence of a non-LE autoimmune disease than the comparators (18.5 vs 7.9%; RR 2.4; 95% CI, 2.1 to 2.6). Correspondingly, the cumulative incidence of a non-LE autoimmune disease during 5 years of follow-up was increased for the patients with CLE: HR 3.5 (95% CI, 3.0 to 4.0).

Limitations

Risk of detection and misclassification bias, mainly pertaining to the CLE group.

Conclusion

Patients with CLE had higher prevalence and 5-year cumulative incidence of a non-LE autoimmune disease than the general population.

Appraising the causal relationship between thyroid function and rheumatoid arthritis: a two-sample bidirectional Mendelian randomization study

Background

Hypothyroidism and hyperthyroidism are observationally associated with rheumatoid arthritis (RA), but causality is unclear. To evaluate the causal relationship between thyroid function and RA, we conducted a two-Sample bidirectional Mendelian Randomization (MR) study.

Methods

Single nucleotide polymorphisms associated with six phenotypes were selected from the FinnGen biobank database, The ThyroidOmics Consortium database, and the IEU Open GWAS database. For the forward MR analysis, we selected hypothyroidism (N=213,390), Graves' disease (GD) (N=199,034), other types of hyperthyroidism (N=190,799), free thyroxine (FT4, N=49,269), and thyroid-stimulating hormone (TSH, N=54,288) as the five related thyroid function phenotypes for exposure, with RA (N=58,284) as the outcome. Reverse MR analysis selected RA as the exposure and five phenotypes of thyroid function as the outcome. The Inverse variance weighting (IVW) method was used as the primary analysis method, supplemented by weighted median (WM) and MR-Egger methods. Cochran's Q test, MR-PRESSO, MR-Egger regression methods, and leave-one-out analysis were employed to assess sensitivity and pleiotropy.

Results

Forward MR evidence indicates that genetic susceptibility to hypothyroidism is associated with an increased risk of RA (ORIvw=1.758, P=7.61×10-5). Reverse MR evidence suggests that genetic susceptibility to RA is associated with an increased risk of hypothyroidism (ORIvw=1.274, P=3.88×10-20), GD (ORIvw=1.269, P=8.15×10-05), and other types of hyperthyroidism (ORIvw=1.141, P=1.80×10-03). There is no evidence to support a forward or reverse causal relationship between genetic susceptibility to RA and FT4, TSH.

Conclusion

Our results provide genetic evidence supporting bidirectional causal relationships between thyroid function and RA. These findings inform preventive strategies and interventions targeting RA and thyroid dysfunction.

Methotrexate is associated with decreased total thyroxine in patients with rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease characterized by joint swelling, pain, and deformation. RA patients have an increased risk of thyroid dysfunction, and drugs of RA treatment may have potential effects on thyroid function.

METHODS

This is a single-center cross-sectional study including 281 inpatients with RA in the First Affiliated Hospital of Guangzhou University of Chinese Medicine. The purpose of this study is to explore the correlation between RA therapeutic drugs and thyroid function. The medical records of 281 inpatients with RA were collected, including general data, laboratory examination, complications, and RA treatment. Spearman correlation analysis was used to explore the association of independent variables with thyroid function and antibodies in RA patients. Multinomial logistics and binary logistic regression were used for multivariate analysis. The statistically significance level was set as P < 0.05. SPSS 22.0 was used for statistical analysis.

RESULTS

Patients taking methotrexate (OR = 0.067, 95%CI: 0.008-0.588, P = 0.015) had lower levels of total thyroxine (TT4) (TT4 < 78.38 nmol/L). There was a negative correlation between glucocorticoids (r = - 0.153, P = 0.010) and total triiodothyronine (TT3) level (TT3 ≥ 1.34 nmol/L), but it was not significant in the multivariate regression model of TT3, although the regression model was statistically significant (P = 0.001).

CONCLUSION

Methotrexate is associated with decreased TT4 levels in RA patients, and glucocorticoids is associated with decreased TT3 levels. Drugs of RA treatment may affect the thyroid function of patients while treating RA, which may be one of the causes of secondary thyroid diseases in RA patients.

Selective Silencing of Disease-Associated B Lymphocytes from Hashimoto's Thyroiditis Patients by Chimeric Protein Molecules

Hashimoto's thyroiditis is one of the most common endocrine disorders, affecting up to 20% of the adult population. No treatment or prevention exists except hormonal substitution for hypothyroidism. We hypothesize that it may be possible to selectively suppress anti-thyroglobulin (Tg) IgG antibody-producing B lymphocytes from HT patients by a chimeric protein molecule containing a monoclonal antibody specific for the human inhibitory receptor CR1, coupled to peptide epitopes derived from Tg protein. We expect that this treatment will down-regulate B-cell autoreactivity by delivering a strong inhibitory signal. Three peptides-two epitope-predicted ones derived from Tg and another irrelevant peptide-were synthesized and then coupled with monoclonal anti-human CR1 antibody to construct three chimeric molecules. The binding to CD35 on human B cells and the effects of the chimeric constructs on PBMC and TMC from patients with HT were tested using flow cytometry, ELISpot assay, and immunoenzyme methods. We found that after the chemical conjugation, all chimeras retained their receptor-binding capacity, and the Tg epitopes could be recognized by anti-Tg autoantibodies in the patients' sera. This treatment downregulated B-cell autoreactivity and cell proliferation, inhibited Tg-specific B-cell differentiation to plasmablasts and promoted apoptosis to the targeted cells. The treatment of PBMCs from HT patients with Tg-epitope-carrying chimeric molecules affects the activity of Tg-specific autoreactive B lymphocytes, delivering to them a strong suppressive signal.

Hypothyroidism risk associated with rheumatoid arthritis: A population-based retrospective cohort study

ABSTRACT

Studies on the thyroid disease risk in patients with rheumatoid arthritis (RA) associated with comorbidities are limited. This population-based retrospective cohort study investigated the hypothyroidism risk in patients with RA and the role of comorbidities.We used Taiwan National Health Insurance Research Database to identify 16,714 RA patients newly diagnosed in 2000 to 2008 and 66,856 control persons without RA, frequency matched by sex, age, and index year. Incidence and the RA group to controls hazard ratio of hypothyroidism were estimated.The hypothyroidism incidence was 1.74-fold higher in the RA group than in controls (16.6 vs 9.52 per 10,000 person-years), with the Cox method estimated adjusted hazard ratio of 1.67 (95% confidence interval = 1.39-2.00) after controlling for covariates. Near 75% of the study population were women, with the incidence 3.6-time higher than men in both groups. The hypothyroidism incidence increased with age, from 12.1 per 1000 person-years in 20 to 39 years to 20.0 per 1000 person-years in 60+ years in RA patients, higher than that in controls (7.17 vs 10.0 per 1000 person-years, respectively by age). Each comorbidity was related to an increased incidence and higher in the RA group than in controls. Among all comorbidities, stroke exerted the greatest impact in the RA group with an adjusted hazard ratio of 3.85 (95% confidence interval = 1.24-12.0).RA patients have an increased risk of developing hypothyroidism; this risk was pronounced in women and the elderly. RA patients should be closely monitored to prevent the development of hypothyroidism.

Association between rheumatoid arthritis and thyroid dysfunction: A meta-analysis and systematic review

OBJECTIVE

Rheumatoid arthritis (RA) is an autoimmune disorder. Multiple studies have investigated the risk of thyroid dysfunction in patients with RA but have reached conflicting conclusions. This systematic review aimed to determine whether patients with RA are at higher risk of thyroid dysfunction.

METHODS

We comprehensively reviewed online literature databases, including PubMed, Scopus, Embase, and the Cochrane Library, from their respective inception dates to March 25, 2022. Studies that provided data on at least one case of thyroid dysfunction in RA patients and their controls were included. Based on these data, we calculated pooled odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) for thyroid dysfunction in RA and non-RA patients.

RESULTS

Twenty-nine studies met the inclusion criteria, involving a total of 35,708 patients with RA. The meta-analysis showed that, compared with non-RA patients, RA patients had an increased risk of developing thyroid dysfunction, particularly hypothyroidism (OR 2.25, 95% CI 1.78-2.84). Subgroup analysis suggested that study type and sample source of control group were the source of heterogeneity.

CONCLUSIONS

Patients with RA are at increased risk of developing thyroid dysfunction, especially hypothyroidism. Routine biochemical examination of thyroid function in RA patients should be strengthened. Larger prospective studies are needed to explore the causal relationship between RA and thyroid dysfunction, and to investigate the impact of thyroid dysfunction on RA disease activity, drug efficacy, and medication safety.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/, identifier CRD42022331142.

Thyroid and COVID-19: a review on pathophysiological, clinical and organizational aspects

BACKGROUND

Thyroid dysfunction has been observed in patients with COVID-19, and endocrinologists are requested to understand this clinical issue. Pandemic-related restrictions and reorganization of healthcare services may affect thyroid disease management.

OBJECTIVE AND METHODS

To analyze and discuss the relationship between COVID-19 and thyroid diseases from several perspectives. PubMed/MEDLINE, Google Scholar, Scopus, ClinicalTrial.gov were searched for this purpose by using free text words and medical subject headings as follows: "sars cov 2", "covid 19", "subacute thyroiditis", "atypical thyroiditis", "chronic thyroiditis", "hashimoto's thyroiditis", "graves' disease", "thyroid nodule", "differentiated thyroid cancer", "medullary thyroid cancer", "methimazole", "levothyroxine", "multikinase inhibitor", "remdesivir", "tocilizumab". Data were collected, analyzed, and discussed to answer the following clinical questions: "What evidence suggests that COVID-19 may induce detrimental consequences on thyroid function?"; "Could previous or concomitant thyroid diseases deteriorate the prognosis of COVID-19 once the infection has occurred?"; "Could medical management of thyroid diseases influence the clinical course of COVID-19?"; "Does medical management of COVID-19 interfere with thyroid function?"; "Are there defined strategies to better manage endocrine diseases despite restrictive measures and in-hospital and ambulatory activities reorganizations?".

RESULTS

SARS-CoV-2 may induce thyroid dysfunction that is usually reversible, including subclinical and atypical thyroiditis. Patients with baseline thyroid diseases are not at higher risk of contracting or transmitting SARS-CoV-2, and baseline thyroid dysfunction does not foster a worse progression of COVID-19. However, it is unclear whether low levels of free triiodothyronine, observed in seriously ill patients with COVID-19, may worsen the disease's clinical progression and, consequently, if triiodothyronine supplementation could be a tool for reducing this burden. Glucocorticoids and heparin may affect thyroid hormone secretion and measurement, respectively, leading to possible misdiagnosis of thyroid dysfunction in severe cases of COVID-19. High-risk thyroid nodules require a fine-needle aspiration without relevant delay, whereas other non-urgent diagnostic procedures and therapeutic interventions should be postponed.

DISCUSSION

Currently, we know that SARS-CoV-2 could lead to short-term and reversible thyroid dysfunction, but thyroid diseases seem not to affect the progression of COVID-19. Adequate management of patients with thyroid diseases remains essential during the pandemic, but it could be compromised because of healthcare service restrictions. Endocrine care centers should continuously recognize and classify priority cases for in-person visits and therapeutic procedures. Telemedicine may be a useful tool for managing patients not requiring in-person visits.

Autoimmune thyroid disorders and rheumatoid arthritis: A bidirectional interplay

Rheumatoid arthritis (RA) and autoimmune thyroid disease (AITD) can occur in the same patient in the autoimmune polyglandular syndrome 2. The association of the two conditions has been recognized long-time ago and the prevalence of AITD in patients with RA and vice versa is well assessed. Geographical variation of AITD and related autoantibodies in RA patients is partly due to ethnic and environmental differences of the studied populations. The impacts of thyroid disorders on RA outcome and vice versa are still controversy. In both AITD and RA genetic susceptibility and environmental factors play a synergic role in the development of the diseases. In this review we aimed at investigating the association of AITD and thyroid autoantibodies with RA, the common pathogenic pathways, the correlation with RA disease activity, and influence of the treatment.

Genome-wide association analysis suggests novel loci for Hashimoto's thyroiditis

PURPOSE

Hashimoto's thyroiditis (HT) is the most common form of autoimmune thyroid diseases. Current knowledge of HT genetics is limited, and not a single genome-wide association study (GWAS) focusing exclusively on HT has been performed to date. In order to decipher genetic determinants of HT, we performed the first GWAS followed by replication in a total of 1443 individuals from Croatia.

METHODS

We performed association analysis in a discovery cohort comprising 405 cases and 433 controls. We followed up 13 independent signals (P < 10^-5) in 303 cases and 302 controls from two replication cohorts and then meta-analyzed results across discovery and replication datasets.

RESULTS

We identified three variants suggestively associated with HT: rs12944194 located 206 kb from SDK2 (P = 1.8 × 10^-6), rs75201096 inside GNA14 (P = 2.41 × 10^-5) and rs791903 inside IP6K3 (P = 3.16 × 10^-5). Genetic risk score (GRS), calculated using risk alleles of these loci, accounted for 4.82% of the total HT variance, and individuals from the top GRS quartile had 2.76 times higher odds for HT than individuals from the lowest GRS quartile.

CONCLUSIONS

Although discovered loci are implicated with susceptibility to HT for the first time, genomic regions harboring these loci exhibit good biological candidacy due to involvement in the regulation of the thyroid function and autoimmunity. Additionally, we observe genetic overlap between HT and several related traits, such as hypothyroidism, Graves' disease and TPOAb. Our study adds a new knowledge of underlying HT genetics and sets a firm basis for further research.

Insulin-like Growth Factor-I Receptor and Thyroid-Associated Ophthalmopathy

Thyroid-associated ophthalmopathy (TAO) is a complex disease process presumed to emerge from autoimmunity occurring in the thyroid gland, most frequently in Graves disease (GD). It is disfiguring and potentially blinding, culminating in orbital tissue remodeling and disruption of function of structures adjacent to the eye. There are currently no medical therapies proven capable of altering the clinical outcome of TAO in randomized, placebo-controlled multicenter trials. The orbital fibroblast represents the central target for immune reactivity. Recent identification of fibroblasts that putatively originate in the bone marrow as monocyte progenitors provides a plausible explanation for why antigens, the expressions of which were once considered restricted to the thyroid, are detected in the TAO orbit. These cells, known as fibrocytes, express relatively high levels of functional TSH receptor (TSHR) through which they can be activated by TSH and the GD-specific pathogenic antibodies that underpin thyroid overactivity. Fibrocytes also express insulin-like growth factor I receptor (IGF-IR) with which TSHR forms a physical and functional signaling complex. Notably, inhibition of IGF-IR activity results in the attenuation of signaling initiated at either receptor. Some studies suggest that IGF-IR-activating antibodies are generated in GD, whereas others refute this concept. These observations served as the rationale for implementing a recently completed therapeutic trial of teprotumumab, a monoclonal inhibitory antibody targeting IGF-IR in TAO. Results of that trial in active, moderate to severe disease revealed dramatic and rapid reductions in disease activity and severity. The targeting of IGF-IR with specific biologic agents may represent a paradigm shift in the therapy of TAO.

Expression of CD62P and CD154 in peripheral blood of patients with rheumatoid arthritis and their correlation with clinical indexes

The aim of this study is to investigate the expression of CD62P and CD154 in peripheral blood of patients with rheumatoid arthritis (RA) and their correlation with the clinical indexes of RA. A total of 60 RA patients diagnosed and treated in the Department of Rheumatism in our hospital from January to December 2016 were selected as the RA group, and 60 cases of healthy subjects were selected as the control group. CD62P and CD154 levels in peripheral blood were determined by flow cytometry using the FACS Vantage flow cytometer, and the correlation analysis with the clinical indexes of RA patients were conducted. The levels of CD62P and CD154 in the peripheral blood of RA group were 28.75% ± 1.48% and 26.84% ± 1.03%, respectively, which were significantly higher than those of the control group ( P < 0.05). The levels of white blood cell (WBC), platelet (PLT), erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), C-reactive protein (CRP), and interleukin (IL)-37 in the RA group were significantly higher than those in the control group ( P < 0.05). Pearson test showed that CD62P and CD154 levels in the peripheral blood in the RA group were positively correlated with serum WBC, PLT, ESR, RF, CRP, IL-37, and disease activity score 28 (DAS28) ( P < 0.05), but not correlated with disease course ( P > 0.05). The expression of CD62P and CD154 in peripheral blood of patients with RA was upregulated, and their expression levels were correlated with the activity of RA and the degree of joint lesion.

Risk of Thyroxine-Treated Autoimmune Thyroid Disease Associated With Disease Onset in Patients With Rheumatoid Arthritis

IMPORTANCE

Autoimmune thyroid disease ([AITD] including hypothyroidism and hyperthyroidism) is the most common organ-specific autoimmune disorder and is more prevalent among patients with rheumatoid arthritis (RA). Real-world studies on when and how this increased risk of AITD develops, in association with the time before or after the onset of RA, are lacking.

OBJECTIVE

To estimate the risk of thyroxine-treated AITD among patients with RA at different time points before and after the diagnosis of RA.

DESIGN, SETTING, AND PARTICIPANTS

A nationwide register-based case-control and cohort study was conducted between January 1, 2006, and June 30, 2013, with a maximum follow-up time of 7 years before and 8 years after diagnosis of RA. The study used the Swedish Rheumatology Quality Register and linkage to other nationwide registers to identify 8090 adults with new-onset RA and a random population-based sample of 80 782 referents matched by age, sex, and residential area. Statistical analysis was performed from July 1, 2015, to June 30, 2017.

EXPOSURES

Presence of AITD in the participants in the case-control design and RA in the participants in the cohort design.

MAIN OUTCOMES AND MEASURES

Prevalence and relative risk of incident AITD before (odds ratios) and after (hazard ratios) diagnosis of RA compared with the population as reference.

RESULTS

There were 8090 patients with RA (5529 women and 2561 men; mean [SD] age, 58.3 [15.2] years) and 80 782 population-based participants as reference who were identified. By the time of diagnosis of RA, the prevalence of AITD was 10.3% among the patients with RA (n = 832) vs 7.1% among the controls (5725 of 80 350) (odds ratio, 1.5; 95% CI, 1.4-1.7). This increased risk of AITD developed during the 5 years (range, 2-5 years) before diagnosis of RA (odds ratio, 1.5; 95% CI, 1.2-1.8) and peaked by the time of diagnosis of RA (range, 0-3 months before diagnosis of RA) (odds ratio, 5.3; 95% CI, 3.7-7.6). From diagnosis of RA and onward, the risk of developing AITD decreased (range, 2-5 years after diagnosis of RA) (hazard ratio, 0.7; 95% CI, 0.5-1.0).

CONCLUSIONS AND RELEVANCE

Compared with the general population, Swedish patients with RA appear to have a higher prevalence of thyroxine-treated AITD at diagnosis of RA and an increased incidence of AITD during the 5-year period before diagnosis of RA. After diagnosis of RA, the risk of developing AITD is suggested to decrease below the expected rate. Besides temporal changes in diagnostic intensity, this pattern of risk raises the question whether AITD may influence the pathogenesis of RA (or vice versa) and, conversely, the question whether antirheumatic therapies may prevent AITD.

Recent advances in understanding autoimmune thyroid disease: the tallest tree in the forest of polyautoimmunity

Autoimmune thyroid disease (AITD) is often observed together with other autoimmune diseases. The coexistence of two or more autoimmune diseases in the same patient is referred to as polyautoimmunity, and AITD is the autoimmune disease most frequently involved. The occurrence of polyautoimmunity has led to the hypothesis that the affected patients suffer from a generalized dysregulation of their immune system. The present review summarizes recent discoveries unravelling the immunological mechanisms involved in autoimmunity, ranging from natural autoimmunity to disease-specific autoimmunity. Furthermore, the clinical grounds for considering AITD in a setting of polyautoimmunity are explored. A better understanding of these may pave the way for designing new treatment modalities targeting the underlying immune dysregulation when AITD appears in the context of polyautoimmunity.