Efficacy and safety of abatacept for systemic juvenile idiopathic arthritis: a systematic review.

OBJECTIVES: This systematic review assessed the efficacy and safety of abatacept in patients with systemic juvenile idiopathic arthritis (JIA). METHODS: Studies published between 2000 and 2021 were searched using PubMed, Embase, Cochrane, Ichushi-Web and clinical trial registries. The risk of bias was assessed according to the manual for development clinical practice guidelines by Minds, a project to promote evidence-based medicine in Japan. RESULTS: Seven observational studies were included. American College of Rheumatology pediatric 30/50/70 responses at 3, 6 and 12 months were 64.8%/50.3%/27.9%, 85.7%/71.4%/42.9% and 80.0%/50.0%/40.0%, respectively. Outcomes on systemic symptoms, joint symptoms and activities of daily living were not obtained. No macrophage activation syndrome or infusion reaction occurred. Serious infection occurred in 2.6% of cases. CONCLUSIONS: Abatacept improved the disease activity index. In addition, abatacept was as safe as interleukin-6 (IL -6) and IL-1 inhibitors. However, both the efficacy and safety data in this systematic review should be reviewed with caution because their quality of evidence is low or very low. Further studies are needed to confirm the efficacy and safety of abatacept for systemic JIA, especially its efficacy on joint symptoms.

Efficacy and safety of tumor necrosis factor inhibitors for systemic juvenile idiopathic arthritis: a systematic review.

OBJECTIVES: This systematic review assessed the efficacy and safety of tumor necrosis factor (TNF) inhibitors in patients with systemic juvenile idiopathic arthritis (JIA). METHODS: Studies were searched using PubMed, Embase, Cochrane, Ichushi-Web, and clinical trial registries (from 2000 to 2021). The risk of bias was assessed using the Cochrane Risk of Bias version 2 for randomized controlled trials (RCTs) and the manual for development clinical practice guidelines by Minds, a project promoting evidence-based medicine in Japan, for observational studies. RESULTS: One RCT and 22 observational studies were included. In the RCT on infliximab, the American College of Rheumatology pediatric (ACR Pedi) 30/50/70 responses at 14 weeks were 63.8%/50.0%/22.4%, with relative risks of 1.30 (95% confidence interval [CI]: 0.94-1.79)/1.48 (95% CI: 0.95-2.29)/1.89 (95% CI: 0.81-4.40), respectively. In the observational studies, ACR Pedi 30/50/70 responses for etanercept at 12 months were 76.7%/64.7%/46.4%, respectively. Infliximab treatment caused anaphylaxis in 17% and an infusion reaction in 23% of patients. The incidence of macrophage activation syndrome, serious infection and malignancy caused by TNF inhibitors was 0%-4%. CONCLUSIONS: Thus, although TNF inhibitors were relatively safe, they were unlikely to be preferentially administered in patients with systemic JIA because of their inadequate efficacy. Further studies, particularly well-designed RCTs, are necessary to confirm the efficacy and safety of TNF inhibitors for systemic JIA.

Survey of diversity awareness and environment among members of the Pediatric Rheumatology Association of Japan.

BACKGROUND: Diversity management has gained traction in Japan. The Pediatric Rheumatology Association of Japan (PRAJ) has an Advisory Committee for Diversity Promotion with a broader focus on promoting diversity. The objectives of this study were to better understand the problems faced by PRAJ members regarding the work environment, childcare and nursing care, and work-life balance. METHODS: A web-based questionnaire was administered to members of the PRAJ and 79 responses were evaluated. RESULTS: Of the respondents, 73% were male and 27% were female. A total of 14% worked for more than 12 h on weekdays, and 22% worked for more than 60 h per week and 38% had fewer than 4 days off per month. Regarding childcare, 54% of the respondents were raising preschool children and 83% had taken parental leave for less than 1 year. A total of 17% of participants had family members in need of care. For both childcare and caregiving, the burden was greater for women. Only 18% of the respondents reported a well-balanced work-life balance, and the most common reasons for a lack of balance were not having enough time, heavy workload, and heavy housework load. CONCLUSIONS: The working hours of the respondents were long, and female members had a greater burden of childcare and caregiving, which was considered a barrier to the career development of women. In the future, there will be a need to promote a sense of equality in diverse human resources, develop support for family life, and shorten working hours.

Clinical practice guidance for childhood-onset systemic lupus erythematosus-secondary publication.

Childhood-onset systemic lupus erythematosus (cSLE) has been recognised as a more acute and severe autoimmune disease than adult-onset SLE. With the development of medications for the disease and supportive therapy, the mortality rate associated with cSLE has drastically improved; the 10-year survival rate among patients with cSLE between 1995 and 2006 in Japan was 98.3%. However, the 10-year survival rate without any permanent functional impairment remained low at 66.1%. Therefore, the current treatment goal for cSLE is to ensure that they can perform normal daily activities throughout their lives by preventing the occurrence and/or progression of organ damage. For this purpose, appropriate treatments and evaluations are required according to the severity and risk of organ damage; however, there are no established guidelines for cSLE. Therefore, the Pediatric Rheumatology Association of Japan and the Pediatric Rheumatology Subcommittee in the Japan College of Rheumatology developed a comprehensive guidance for clinical practice based on cSLE-related data collected from Japanese national surveys and relevant articles from both domestic and international sources. However, due to the lack of indications for defined and objective evidence quality levels, this guidance should be used on the basis of the judgement of the attending physicians for individual patients.

Clinical impact of myositis-specific autoantibodies on long-term prognosis of juvenile idiopathic inflammatory myopathies: multicentre study.

OBJECTIVES: This study aimed to investigate the clinical characteristics, treatment and prognosis of juvenile idiopathic inflammatory myopathies (JIIM) in Japan for each myositis-specific autoantibody (MSA) profile. METHODS: A multicentre, retrospective study was conducted using data of patients with JIIM at nine paediatric rheumatology centres in Japan. Patients with MSA profiles, determined by immunoprecipitation using stored serum from the active stage, were included. RESULTS: MSA were detected in 85 of 96 cases eligible for the analyses. Over 90% of the patients in this study had one of the following three MSA types: anti-melanoma differentiation-associated protein 5 (MDA5) (n = 31), anti-transcriptional intermediary factor 1 alpha and/or gamma subunits (TIF1γ) (n = 25) and anti-nuclear matrix protein 2 (NXP2) (n = 25) antibodies. Gottron papules and periungual capillary abnormalities were the most common signs of every MSA group in the initial phase. The presence of interstitial lung disease (ILD) was the highest risk factor for patients with anti-MDA5 antibodies. Most patients were administered multiple drug therapies: glucocorticoids and MTX were administered to patients with anti-TIF1γ or anti-NXP2 antibodies. Half of the patients with anti-MDA5 antibodies received more than three medications including i.v. CYC, especially patients with ILD. Patients with anti-MDA5 antibodies were more likely to achieve drug-free remission (29 vs 21%) and less likely to relapse (26 vs 44%) than others. CONCLUSION: Anti-MDA5 antibodies are the most common MSA type in Japan, and patients with this antibody are characterized by ILD at onset, multiple medications including i.v. CYC, drug-free remission, and a lower frequency of relapse. New therapeutic strategies are required for other MSA types.

External validation of the EULAR/ACR idiopathic inflammatory myopathies classification criteria with a Japanese paediatric cohort.

OBJECTIVES: To assess the performance of the EULAR/ACR idiopathic inflammatory myopathies (IIMs) classification criteria to classify juvenile IIMs (JIIMs) in an Asian paediatric population. METHODS: Sixty-eight JIIM patients and 49 non-JIIM patients diagnosed at seven major paediatric rheumatology centres in Japan between 2008 and 2015 were enrolled. Retrospective data were collected, and each patient's data form was submitted. The expert group reviewed the forms and re-examined the diagnoses. The EULAR/ACR criteria were then applied and the probability of having JIIM was determined for each case. The sensitivity and specificity of the EULAR/ACR criteria were compared with those of other existing criteria. RESULTS: The sensitivity/specificity of the EULAR/ACR classification criteria were 92.1/100% with muscle biopsy data (n = 38); 86.7/100% without muscle biopsy data (n = 30) and 89.7/100% in our total cohort (n = 68). The sensitivity of Bohan and Peter's criteria and Tanimoto's criteria were 80.9 and 64.7% in our total cohort, respectively. Among 68 physician-diagnosed JIIM patients, seven cases (three JDM and four overlap myositis) were not classified as JIIM because the probability did not reach the cut-off point (55%). The three JDM patients all presented with only one of the three skin manifestations that are listed in the criteria: Gottron's sign. CONCLUSION: Our validation study with Japanese JIIM cases indicates that the EULAR/ACR classification criteria for IIM generally perform better than existing diagnostic criteria for myositis.

Clinical practice guidance for juvenile dermatomyositis (JDM) 2018-Update.

Juvenile dermatomyositis is the most common type of juvenile idiopathic inflammatory myopathy mainly affecting the skin and proximal muscles. We have published the Japanese version of 'Clinical practice guidance for juvenile dermatomyositis (JDM) 2018 'consisting of a review of articles in the field and evidence-informed consensus-based experts' opinion on the treatment strategy in collaboration with The Pediatric Rheumatology Association of Japan and The Japan College of Rheumatology under the financial support by 'Research on rare and intractable diseases, Health and Labor Sciences Research Grants'. This article is a digest version of the Japanese guidance.

Characteristics of FDG-PET findings in the diagnosis of systemic juvenile idiopathic arthritis.

OBJECTIVE: To examine and delineate inflammatory focus in patients with juvenile idiopathic arthritis (JIA), (18)F-Fluoro-deoxy-glucose (FDG)-positron emission tomography (PET) ((18)F-FDG-PET) was applied to patients with JIA, and the images of these patients were compared. METHODS: Sixty-eight children (59 with systemic JIA (s-JIA) and 9 with polyarticular JIA) were included. The diagnosis of JIA was done to meet the International League of Associations for Rheumatology (ILAR) criteria. After 6-h fasting, whole-body positron emission tomography (PET) scans were acquired 60 min after intravenous injection of 3-5 MBq/kg (18)F-FDG. The interpretation of (18)F-FDG uptake was based on visual characteristics. RESULTS: Two types of PET images were outstanding in s-JIA; one was (18)F-FDG uptake in red bone marrow, such as the spine, pelvis, and long bones as well as spleen (12 cases), and other type was the uptake in the major joints, such as hips, elbows, wrists, knees, and ankles (8 cases). The former findings were correlated with elevated levels of inflammatory markers, while the latter were with significantly increased levels of MMP-3 (p < 0.05). CONCLUSION: There was a noticeable accumulation of (18)F-FDG uptake in bone marrow of s-JIA patients which may indicate the inflammatory focus of this disease and play an important role in the pathogenic basis of arthritis and systemic inflammation of s-JIA.

Pathogenesis of systemic inflammatory diseases in childhood: "Lessons from clinical trials of anti-cytokine monoclonal antibodies for Kawasaki disease, systemic onset juvenile idiopathic arthritis, and cryopyrin-associated periodic fever syndrome".

Inflammation has often been considered to be a nonspecific response and to play a bridging role in the activation of adaptive immunity. However, it is now accepted that inflammation is the product of an independent innate immune system closely linked to the adaptive immune system. The key mediators of inflammation are inflammatory cytokines, as determined by multiple lines of evidence both in vitro and in vivo. Due to the crucial role of inflammatory cytokines in the pathogenesis of autoimmune disorders, anti-cytokine treatment has been developed as a therapy for rheumatoid arthritis, juvenile idiopathic arthritis (JIA), and inflammatory bowel diseases. We recently completed several clinical trials of anti-cytokine treatment for children with systemic inflammatory diseases: anti-IL-6 receptor monoclonal antibody (tocilizumab) for children with two subtypes of JIA (poly-JIA and systemic JIA), anti-TNF-α monoclonal antibody (infliximab) for children with Kawasaki disease, and anti-IL-1-ß monoclonal antibody (canakinumab) for children with cryopyrin-associated periodic syndrome. This review summarizes the basis of inflammation in terms of innate immunity and adaptive immunity in these systemic inflammatory diseases, clinical efficacy, and tolerability of these biologic agents, and attempts to determine the roles of individual inflammatory cytokines in disease pathogenesis.

Biological differential diagnosis of follicular thyroid tumor and Hürthle cell tumor on the basis of telomere length and hTERT expression.

BACKGROUND: The most difficult thyroid tumors to diagnose by histology are follicular carcinomas (FTCs) and Hürthle cell carcinomas (HCCs). Telomere alteration and human telomerase reverse transcriptase (hTERT) expression have been observed in most human cancers and are known to be a feature of malignancy. The purpose of this study was to clarify whether hTERT protein expression and telomere alteration could be applicable biological markers for distinguishing FTC from HCC. METHODS: We investigated a total of 78 thyroid tumor cases, including 14 FTCs, 47 follicular adenomas (FTAs), 5 HCCs, and 12 Hürthle cell adenomas (HCAs). hTERT protein expression was examined by immunohistochemistry, and telomere length was determined by tissue quantitative fluorescence in situ hybridization. RESULTS: Positivity for hTERT protein expression was observed in 86 % of FTCs and 49 % of FTAs. Telomeres in FTCs were significantly shorter than those in FTAs. All HCCs and HCAs (100 %) expressed hTERT protein. Telomeres in HCCs were significantly shorter than those in HCAs. CONCLUSIONS: Our results suggest that hTERT protein expression and telomere shortening would be applicable as biological markers to distinguish FTC from FTA. Previous studies have suggested that follicular tumor and Hürthle cell tumor should be classified biologically as distinct tumors. All Hürthle cell tumors expressed hTERT protein and HCCs had markedly shortened telomeres, suggesting that follicular tumor and Hürthle cell tumor might be biologically distinct entities.

Characterization of methicillin-resistant Staphylococcus pseudintermedius isolated from dogs and cats.

The aim of this study was to explore the presence of methicillin-resistant Staphylococcus pseudintermedius (MRSP) in a collection of S. pseudintermedius strains isolated from dogs and cats with dermatitis in Japan and to compare their genotypic and phenotypic characteristics. Clonal relationships were determined by pulse field gel electrophoresis (PFGE), staphylococcal chromosomal cassette mec (SCCmec) typing, and multilocus sequence typing (MLST). Biofilm formation assay was performed using safranin staining in microplates. Three virulence genes coding for S. intermedius exfoliative toxin and Panton-Valentine leukocidin (siet, lukS-PV and lukF-PV) were searched for in a collection of strains. Antimicrobial resistance against 15 antibiotics was studied by a disc diffusion method. Twenty-seven MRSP were isolated. According to PFGE results the isolates were not closely related except for a few strains. MLST showed that the strains belonged to five groups, ST71 and ST26 being the two most prevalent. Three types of SCCmec (II, II-III and V) were identified. All isolates were siet-positive but PVL-negative. Most strains (except for two) produced strong biofilm in tryptic soy broth with glucose. Seventy-eight percent of the isolates were resistant or intermediate to twelve or more antibiotics. Our study demonstrates that the ST71 lineage is widespread in Japan and that ST26 could represent an emerging lineage. Moreover, most of our strains are capable of forming strong biofilm and possess siet gene, two virulence characteristics that probably help the bacteria to persist and spread. Finally, our MRSP strains show a strong resistance profile to antibiotics commonly used in veterinary medicine.

COVID-19 and adult-onset Still's disease as part of hyperferritinemic syndromes.

The coronavirus disease (COVID-19) is known to cause hyperferritinemia and haemophagocytic lymphohistiocytosis. Including this laboratory parameter, symptoms similar to COVID-19 have been observed in adult-onset Still's disease (AOSD), catastrophic antiphospholipid syndrome, macrophage activation syndrome, and septic shock, which has led to the proposal of a concept called 'hyperferritinemic syndromes'. High levels of some clinical markers in both COVID-19 and AOSD make them difficult to differentiate. While the efficacy of ciclesonide had been expected for mild pneumonia with COVID-19, the efficacy of tocilizumab (TCZ), which is a known treatment for AOSD, was not established. We report the first known occurrence of COVID-19 diagnosed in March 2020, preceded by the diagnosis of AOSD in April 2019. The patient was given prednisolone and TCZ, which led to remission. With the dyspnea and ground-glass appearance on chest computed tomography, PCR test revealed COVID-19 infection. Ciclesonide was started on Day 7 of the disease onset, which led to improved inflammatory markers. We infer that while TCZ is theoretically useful for COVID-19 due to its inhibition of interleukin 6. AOSD and COVID-19 may be differentiated by levels of ferritin, and appropriate treatment must be allocated.

Serum gasdermin D levels are associated with the chest computed tomography findings and severity of COVID-19.

BACKGROUND: The role of programmed cell death, especially pyroptosis and apoptosis, in unfavorable immune responses in COVID-19 remains to be elucidated. METHODS: We conducted a cross-sectional analysis to investigate the association between the serum gasdermin D (GSDMD) levels, a pyroptotic marker, and caspase-cleaved cytokeratin 18 fragment (M30), an apoptotic marker, and the clinical status and abnormal chest computed tomography (CT) findings in patients with COVID-19. RESULTS: In this study, 46 patients diagnosed with COVID-19 were divided into the following three groups according to the disease severity: mild to moderate group (n = 10), severe group (n = 14), and critical group (n = 22). The serum GSDMD levels were higher in the critical group than in the mild to moderate group (P = 0.016). In contrast, serum M30 levels were lower in the critical group than in the severe group (P = 0.048). Patients who required mechanical ventilation or died had higher serum GSDMD levels than those who did not (P = 0.007). Area of consolidation only and of ground glass opacity plus consolidation positively correlated with serum GSDMD levels (r = 0.56, P < 0.001 and r = 0.53, P < 0.001, respectively). CONCLUSION: Higher serum GSDMD levels are associated with critical respiratory status and the consolidation area on chest CT in patients with COVID-19, suggesting that excessive activation of pyroptosis may affect the clinical manifestations in patients with COVID-19.

Potentiation of TLR9 responses for human naïve B-cell growth through RP105 signaling.

Toll-like receptor 9 (TLR9) signals induce important pathways in the early defense against microbial pathogens. Although TLR9 signaling can activate memory B cells directly, efficient naïve B cell responses seem to require additional, but as yet unidentified, signals. We explored the effects of RP105 (CD180) on CpG DNA-activated naïve and memory B cells from normal controls and patients with common variable immunodeficiency (CVID). RP105 dramatically enhanced CpG DNA-induced proliferation/survival by naïve B cells but not by memory B cells. This enhancement was mediated by TLR9 upregulation induced by RP105, leading to Akt activation and sustained NF-kappaB activation. CpG DNA-activated CVID B cells showed enhancement of proliferation/survival by RP105 and produced specific IgM antibody to Streptococcus pneumoniae polysaccharides in response to interleukin-21 stimulation. Thus, RP105 strongly affects expansion of the naïve B-cell pool, and suggests that the putative RP105 ligand (s) upon cytokine stimulation facilitates antibody-mediated acute pathogen clearance.

A case of familial Mediterranean fever associated with compound heterozygosity for the pyrin variant L110P-E148Q/M680I in Japan.

Familial Mediterranean fever (FMF) is an autosomal recessive disorder characterized by recurrent and self-limited fever attacks and serositis/arthritis. The M694V, M694I, M680I, V726A, and E148Q mutations in MEFV, the gene responsible for FMF, account for most FMF cases in Mediterranean populations. In Japan, M694I and E148Q are most frequently detected; M694V, M680I, and V726A have not been identified so far. We report the first case of FMF associated with M680I in Japan.

Distinct response in maintenance of human naive and memory B cells via IL-21 receptor and TCL1/Akt pathways.

The molecular mechanisms involving in B-cell survival/proliferation are poorly understood. Here we investigated the molecules affecting the survival of human naïve and memory B cells. Without stimulation, naïve B cells survived longer than memory B cells. Moreover, the viability of memory B cells decreased more rapidly than that of naïve B cells following with Staphylococcus aureus Cowan strain (SAC), anti-immunoglobulin (Ig), or anti-CD40 stimulation, but displayed the same levels of survival following CpG DNA stimulation. We analyzed the transcriptional differences between B-cell subsets by gene expression profiling, and identified 15 genes significantly correlated to survival/proliferation. Among them, IL-21 receptor (IL-21R) and T-cell leukemia 1 (TCL1) proto-oncogene were highly expressed in naïve B cells. IL-21 induced the proliferation of both naïve and memory B cells. Marked phosphorylation of Akt was found in naïve B cells compared with memory B cells. This study suggests that naive and memory B cells are regulated by several distinct molecules, and the IL-21R and TCL1/Akt pathways might play crucial roles in naïve B cells for their maintenance.

[Familial Mediterranean fever as representative autoinflammatory disease].

Familial Mediterranean fever (FMF) is the most common of the hereditary periodic fevers. FMF is an autosomal recessive disease that affects populations among non-Ashkenazi Jews, Arabs, Turks, and Armenians. Yet, it is observed worldwide, and approximately 90 FMF patients have been reported in Japan. FMF is caused by mutations in the MEFV gene, which encodes the pyrin protein. Pyrin protein is associated with the interleukin (IL)-1-related inflammation cascade and involved in the regulation of apoptosis and inflammation. The clinical characteristics of FMF attacks are fever, abdominal pain, chest pain, and arthritis as symptoms of serositis. Reactive or secondary AA amyloidosis is the most devastating complication of FMF. As amyloid slowly accumulates in various organs and tissues, organ dysfunction ensues prominently in the kidneys. Colchicine has been used in the treatment of FMF, and has markedly changed the course of the disease. Although over 80 mutations in the MEFV gene have been reported, the majority of cases are caused by four mutations in exon 10: M694V, M694I, V726A, and M680I. The majority of Japanese FMF patients are compound heterozygous for M694I/E148Q. E148Q, which is found in populations of Japanese and Chinese, is considered to be a functional polymorphism. It is intriguing that about 10% of Japanese FMF patients have the L110P mutation in addition to E148Q in the same allele. Allelic frequencies of MEFV mutations and polymorphisms in 500 normal Japanese individuals were 0% for M694I and 23% for E148Q, respectively. In conclusion, FMF is not a rare disease in Japan, and it is necessary to consider FMF when a patient experiences recurrent attacks of fever and serositis.

Validation of Classification Criteria of Macrophage Activation Syndrome in Japanese Patients With Systemic Juvenile Idiopathic Arthritis.

OBJECTIVE: To validate whether the 2016 American College of Rheumatology/European League Against Rheumatism classification criteria of macrophage activation syndrome (MAS) complicating systemic juvenile idiopathic arthritis (JIA) is practical in the real world. METHODS: A combination of expert consensus and analysis of real patient data was conducted by a panel of 15 pediatric rheumatologists. A total of 65 profiles comprised 18 patients with systemic JIA-associated MAS and 47 patients with active systemic JIA without evidence of MAS. From these profiles, 10 patient data points for full-blown MAS, 11 patient data points for MAS onset, and 47 patient data points for acute systemic JIA without MAS were evaluated. RESULTS: Evaluation of the classification criteria to discriminate full-blown MAS from acute systemic JIA without MAS showed a sensitivity of 1.000 and specificity of 1.000 at the time of full-blown MAS. Sensitivity was 0.636 and specificity was 1.000 at the time of MAS onset. The number of measurement items that fulfilled the criteria increased in full-blown MAS compared to that at MAS onset. At MAS onset, the positive rates of patients who met the criteria for platelet counts and triglycerides were low, whereas those for aspartate aminotransferase were relatively high. At full-blown MAS, the number of patients who met the criteria for each measurement item increased. CONCLUSION: The classification criteria for MAS complicating systemic JIA had a very high diagnostic performance. However, the diagnostic sensitivity for MAS onset was relatively low. For the early diagnosis of MAS in systemic JIA, the dynamics of laboratory values during the course of MAS should be further investigated.

Suppression of iodide uptake and thyroid hormone synthesis with stimulation of the type I interferon system by double-stranded ribonucleic acid in cultured human thyroid follicles.

Although viral infection is thought to be associated with subacute thyroiditis and probably with autoimmune thyroid disease, possible changes in thyroid function during the prodromal period of infection or subclinical infection remain largely unknown. Recently, it was shown that pathogen-associated molecular patterns stimulate Toll-like receptors (TLR) and activate innate immune responses by producing type I interferons (IFN). Using a human thyroid follicle culture system, in which de novo synthesized thyroid hormones are released into the culture medium under physiological concentrations of human TSH, we studied the effects of polyinosinic-polycytidylic acid [Poly(I:C)], a chemical analog of viral double-stranded RNA (dsRNA), on TSH-induced thyroid function. Thyrocytes expressed ligands for dsRNA (TLR 3, CD14, and retinoic-acid-inducible protein-1) comparable with the TSH receptor. DNA microarray and real-time PCR analyses revealed that dsRNA increased the expression of mRNA for TLR3, IFN-beta, IFN-regulating factors, proinflammatory cytokines, and class I major histocompatibility complex (MHC), whereas genes associated with thyroid hormonogenesis (sodium/iodide symporter, peroxidase, deiodinases) were suppressed. In accordance to these data, Poly(I:C) suppressed TSH-induced 125I uptake and hormone synthesis dose dependently, accompanied by a decrease in the ratio of 125I-T3/125I-T4 released into the culture medium, whereas peptidoglycan, lipopolysaccharides, or unmethylated CpG DNA, ligands for TLR2, TLR4, and TLR9, respectively, had no significant effect. These inhibitory effects of Poly(I:C) were not blocked by a neutralizing antibody against TLR3 and an anti-IFN alpha/beta receptor antibody. These in vitro findings suggest that when thyrocytes are infected with certain viruses, dsRNA formed intracellularly in thyrocytes may be a cause for thyroid dysfunction, leading to development of autoimmune thyroiditis.

Amiodarone reversibly decreases sodium-iodide symporter mRNA expression at therapeutic concentrations and induces antioxidant responses at supraphysiological concentrations in cultured human thyroid follicles.

CONTEXT: Amiodarone, a potent antiarrhythmic, iodine-containing agent, is a highly active oxidant exerting cytotoxic effects on thyrocytes at pharmacological concentrations. Patients receiving amiodarone usually remain euthyroid, but occasionally develop thyroid dysfunction. Although there is a general consensus that amiodarone-associated hypothyroidism is iodine induced, the destructive mechanism of thyroid follicles in amiodarone-induced thyrotoxicosis remains unknown. OBJECTIVE: To elucidate the mechanism by which amiodarone elicits thyroid dysfunction. DESIGN: Human thyroid follicles were cultured with thyroid-stimulating hormone (TSH) and amiodarone at therapeutic (1-2 microM) and pharmacological (10-20 microM) concentrations, and the drug-induced effect on whole human gene expression was analyzed by cDNA microarray. Microarray data were confirmed by real-time PCR and Western blot. MAIN OUTCOMES: Amiodarone at 1-2 muM decreased the expression level of the sodium-iodide symporter (NIS) to nearly half, but did not affect genes participating in thyroid hormonogenesis (thyroid peroxidase, thyroglobulin, pendrin, and NADPH oxidase). Higher concentrations (10-20 microM) decreased the expression of all these genes, accompanied by increased expression of antioxidant proteins such as heme oxygenase 1 and ferritin. When thyroid follicles obtained from a patient with Graves' disease who had been treated with amiodarone were cultured in amiodarone-free medium, TSH-induced thyroid function was intact, suggesting that amiodarone at a maintenance dose did not elicit any cytotoxic effect on thyrocytes. The ultrastructural features of cultured thyroid follicles were compatible with these in vitro findings. CONCLUSION: These in vitro and ex vivo findings suggest that patients taking maintenance doses of amiodarone usually remain euthyroid, probably due to escape from the Wolff-Chaikoff effect mediated by decreased expression of NIS mRNA. Further, amiodarone is not cytotoxic for thyrocytes at therapeutic concentrations but elicits cytotoxicity through oxidant activity at supraphysiological concentrations. We speculate that when amiodarone-induced prooxidant activity somehow exceeds the endogenous antioxidant capacity, the thyroid follicles will be destroyed and amiodarone-induced destructive thyrotoxicosis may develop.