A thyroid hormone network exists in synovial fibroblasts of rheumatoid arthritis and osteoarthritis patients

Sleep duration and the risk of new-onset arthritis in middle-aged and older adult population: results from prospective cohort study in China

Background

The pain and sleep disorders caused by arthritis are health issues that have been re-emphasized with the aging population. However, the majority of research on arthritis and sleep disorders has focused on cases that have already been diagnosed with arthritis. This research aims to explore the correlation between sleep duration and new-onset arthritis in middle-aged and older adult individuals.

Methods

Utilizing data from the China Health and Retirement Longitudinal Study from baseline (2011) to the Wave 3 follow-up (2018), we conducted a 7-year longitudinal investigation targeting populations with valid sleep questionnaire records and without arthritis. Sleep duration was assessed from nighttime sleep and daytime nap records. The new-onset of arthritis was determined based on self-reported diagnosis. We employed different logistic regression models to consider the potential impact of sleep duration on arthritis and conducted mediation analyses to assess the involvement of BMI in the association between sleep duration and the new-onset risk of arthritis.

Results

Out of the 6,597 individuals analyzed in the cohort, 586 (8.9%) were diagnosed with new-onset arthritis. Median sleep duration was notably shorter in the new-onset arthritis group (6.63 vs. 6.41 h, p < 0.05). There was a notable negative correlation found between new-onset risk of arthritis and sleep duration, with each Interquartile Range (IQR) increment in sleep leading to a 16% risk reduction (OR: 0.864; 95% CI: 0.784-0.954). Stratified analyses revealed BMI as a potential modifier in the sleep-arthritis relationship (P for interaction = 0.05). Mediation analyses further showed that about 3.5% of the association was mediated by BMI. Additionally, the inclusion of sleep duration improved the arthritis predictive power of our model, with an IDI of 0.105 (0.0203, 0.1898) and an NRI of 0.0013 (0.0004, 0.0022) after adding sleep duration to the basic model.

Conclusion

In the middle-aged and older adult demographic of China, increased sleep duration is associated with a decreased new-onset risk of arthritis, with BMI potentially playing a role in mediating this connection.

Autoimmune thyroid disease and rheumatoid arthritis: where the twain meet

Autoimmune thyroid disease (AITD) is the most prevalent autoimmune disease. It shares multiple genetic, clinical, and serologic characteristics with rheumatoid arthritis (RA). Although frequently described as a classic form of single-organ autoimmunity, the AITD disease burden in a subset of patients extends well beyond the thyroid gland. This review explores the complex interaction between the two diseases and the clinical consequences when they overlap. Beyond the well-known effects of AITD on thyroid function in RA, there is mounting evidence of the association of both conditions impacting the presentation and outcomes of diabetes, metabolic syndrome, and cardiovascular disease. An increasing number of studies suggest that there are negative effects of AITD on RA disease activity both in the presence and in the absence of thyroid dysfunction. Recent evidence suggests that AITD may not only worsen the cumulative damage of RA through higher disease activity but may also worsen secondary osteoarthritis changes. Less well-known is the significant association between AITD and chronic widespread pain syndromes including fibromyalgia. Importantly, the presence of fibromyalgia, which is increased in RA patients, appears to be further increased when it overlaps with AITD. Lastly, we probe the possible influence of AITD interacting with RA on fertility and clinical depression. Key Points • Autoimmune thyroid disease is the most common autoimmune disease and is frequently associated with rheumatoid arthritis. • Autoimmune thyroid disease can present with osteoarthritis, inflammatory arthritis, and chronic widespread pain syndromes. • The co-occurrence of autoimmune thyroid disease and rheumatoid arthritis may worsen disease activity and exacerbate other disease manifestations including cardiovascular disease, fertility, and depression. • The overlap of rheumatoid arthritis with autoimmune thyroid disease needs further research and should be sought in general clinical practice.

Selected musculoskeletal disorders in patients with thyroid dysfunction, diabetes, and obesity

Many medical conditions affect the skeletal system and constitute independent risk factors for fractures. The action of thyroid hormones is necessary to maintain adequate development, mineralization, and bone strength. Untreated hyperthyroidism can lead to a decrease in bone mineral density (BMD), osteoporosis, and pathological fractures. In hypothyroidism, the changes in the quality of bone structure lead to an increase in the frequency of fractures. Excessive body weight negatively impacts fracture risk, increases the risk of osteoarthritis and accelerates the development of rheumatoid arthritis and osteoporosis. Type 1 and type 2 diabetes are associated with an increased risk of bone fractures despite different etiopathogenesis due to the duration of the disease and the pro-inflammatory state, the incorporation of advanced glycation end products (AGEs) into the bone matrix, and microvascular disorders. This study summarizes the current literature on the influence of thyroid dysfunction, obesity, and diabetes on the skeletal system.

Levothyroxine use and longitudinal changes in thigh muscles in at-risk participants for knee osteoarthritis: preliminary analysis from Osteoarthritis Initiative cohort

BACKGROUND

We examined the association between levothyroxine use and longitudinal MRI biomarkers for thigh muscle mass and composition in at-risk participants for knee osteoarthritis (KOA) and their mediatory role in subsequent KOA incidence.

METHODS

Using the Osteoarthritis Initiative (OAI) data, we included the thighs and corresponding knees of participants at risk but without established radiographic KOA (baseline Kellgren-Lawrence grade (KL) < 2). Levothyroxine users were defined as self-reported use at all annual follow-up visits until the 4th year and were matched with levothyroxine non-users for potential confounders (KOA risk factors, comorbidities, and relevant medications covariates) using 1:2/3 propensity score (PS) matching. Using a previously developed and validated deep learning method for thigh segmentation, we assessed the association between levothyroxine use and 4-year longitudinal changes in muscle mass, including cross-sectional area (CSA) and muscle composition biomarkers including intra-MAT (within-muscle fat), contractile percentage (non-fat muscle CSA/total muscle CSA), and specific force (force per CSA). We further assessed whether levothyroxine use is associated with an 8-year risk of standard KOA radiographic (KL ≥ 2) and symptomatic incidence (incidence of radiographic KOA and pain on most of the days in the past 12 months). Finally, using a mediation analysis, we assessed whether the association between levothyroxine use and KOA incidence is mediated via muscle changes.

RESULTS

We included 1043 matched thighs/knees (266:777 levothyroxine users:non-users; average ± SD age: 61 ± 9 years, female/male: 4). Levothyroxine use was associated with decreased quadriceps CSAs (mean difference, 95%CI: - 16.06 mm²/year, - 26.70 to - 5.41) but not thigh muscles' composition (e.g., intra-MAT). Levothyroxine use was also associated with an increased 8-year risk of radiographic (hazard ratio (HR), 95%CI: 1.78, 1.15-2.75) and symptomatic KOA incidence (HR, 95%CI: 1.93, 1.19-3.13). Mediation analysis showed that a decrease in quadriceps mass (i.e., CSA) partially mediated the increased risk of KOA incidence associated with levothyroxine use.

CONCLUSIONS

Our exploratory analyses suggest that levothyroxine use may be associated with loss of quadriceps muscle mass, which may also partially mediate the increased risk of subsequent KOA incidence. Study interpretation should consider underlying thyroid function as a potential confounder or effect modifier. Therefore, future studies are warranted to investigate the underlying thyroid function biomarkers for longitudinal changes in the thigh muscles.

Causal relationship between thyroid dysfunction and hallux valgus: A two-sample Mendelian randomization study

INTRODUCTION

Previous observational studies have reported that thyroid dysfunction is associated with hallux valgus (HV). However, the causal effect of thyroid dysfunction on hallux valgus is still unknown. To assess whether there is a causal relationship between thyroid dysfunction and hallux valgus, we performed a two-sample Mendelian randomization (MR) study.

METHODS

The data of the two-sample Mendelian randomization study were obtained from public databases. In this study, hypothyroidism, hyperthyroidism, free thyroxine (FT4), and thyrotropin (TSH) were chosen as exposures. The single nucleotide polymorphisms (SNP) of hypothyroidism and hyperthyroidism were from the genome-wide association studies (GWAS) of the IEU database, including 337,159 subjects. Data for FT4 and TSH (72,167 subjects) were extracted from the ThyroidOmics Consortium. HV was used as the outcome. The SNPs associated with HV were selected from a GWAS of 202,617 individuals in the fignngen database. The inverse variance weighted (IVW) method was used as the primary analysis. Four complementary methods were applied, including MR-presso, MR-Egger, and weighted median. In addition, Cochran's Q test, MR-presso, MR-Egger regression, and the leave-one-out test were used as sensitivity analysis, and the MR-pleiotropy test was performed to examine pleiotropy.

RESULTS

According to the results of IVW, we found that there was a causal relationship between hypothyroidism and HV, and hypothyroidism increased the incidence of HV (OR = 2.838 (95% CI: 1.116-7.213); p = 0.028). There were no significant causal effects of hyperthyroidism, FT4, and TSH on HV (p > 0.05). Sensitivity analyses showed that the results were robust and reliable, and no horizontal pleiotropy was detected.

CONCLUSIONS

Our findings provided genetic support that hypothyroidism might increase the risk of HV. It will predict the occurrence of HV in patients with hypothyroidism and provide suggestions for early prevention and intervention.

Clustering of comorbidities and associated outcomes in people with osteoarthritis - A UK Clinical Practice Research Datalink study

OBJECTIVE

To examine the clusters of chronic conditions present in people with osteoarthritis and the associated risk factors and health outcomes.

METHODS

Clinical Practice Research Datalink (CPRD) GOLD was used to identify people diagnosed with incident osteoarthritis (n = 221,807) between 1997 and 2017 and age (±2 years), gender, and practice matched controls (no osteoarthritis, n = 221,807) from UK primary care. Clustering of people was examined for 49 conditions using latent class analysis. The associations between cluster membership and covariates were quantified by odds ratios (OR) using multinomial logistic regression. General practice (GP) consultations, hospitalisations, and all-cause mortality rates were compared across the clusters identified at the time of first diagnosis of osteoarthritis (index date).

RESULTS

In both groups, conditions largely grouped around five clusters: relatively healthy; cardiovascular (CV), musculoskeletal-mental health (MSK-MH), CV-musculoskeletal (CV-MSK) and metabolic (MB). In the osteoarthritis group, compared to the relatively healthy cluster, strong associations were seen for 1) age with all clusters; 2) women with the MB cluster (OR 5.55: 5.14-5.99); 3) obesity with the CV-MSK (OR 2.11: 2.03-2.20) and CV clusters (OR 2.03: 1.97-2.09). The CV-MSK cluster in the osteoarthritis group had the highest number of GP consultations and hospitalisations, and the mortality risk was 2.45 (2.33-2.58) times higher compared to the relatively healthy cluster.

CONCLUSIONS

Of the five identified clusters, CV-MSK, CV, and MSK-MH are more common in OA and CV-MSK cluster had higher health utilisation. Further research is warranted to better understand the mechanistic pathways and clinical implications.

DNA Methylation of T Lymphocytes as a Therapeutic Target: Implications for Rheumatoid Arthritis Etiology

Rheumatoid arthritis (RA) is an autoimmune disease that can cause joint damage and disability. Epigenetic variation, especially DNA methylation, has been shown to be involved in almost all the stages of the pathology of RA, from autoantibody production to various self-effector T cells and the defects of protective T cells that can lead to chronic inflammation and erosion of bones and joints. Given the critical role of T cells in the pathology of RA, the regulatory functions of DNA methylation in T cell biology remain unclear. In this review, we elaborate on the relationship between RA pathogenesis and DNA methylation in the context of different T cell populations. We summarize the relevant methylation events in T cell development, differentiation, and T cell-related genes in disease prediction and drug efficacy. Understanding the epigenetic regulation of T cells has the potential to profoundly translate preclinical results into clinical practice and provide a framework for the development of novel, individualized RA therapeutics.

Changes in Thyroid Hormone Signaling Mediate Cardiac Dysfunction in the Tg197 Mouse Model of Arthritis: Potential Therapeutic Implications

Background Rheumatoid Arthritis (RA) patients show a higher risk of heart failure. The present study investigated possible causes of cardiac dysfunction related to thyroid hormone (TH) signaling in a RA mouse model. Methods A TNF-driven mouse model of RA[TghuTNF (Tg197)] was used. Cardiac function was evaluated by echocardiography. SERCA2a and phospholamban protein levels in left ventricle (LV) tissue, thyroid hormone levels in serum, TH receptors in LV and TH-related kinase signaling pathways were measured. T3 hormone was administered in female Tg197 mice. Results We show LV and atrial dilatation with systolic dysfunction in Tg197 animals, accompanied by downregulated SERCA2a. We suggest an interaction of pro-inflammatory and thyroid hormone signaling indicated by increased p38 MAPK and downregulation of TRβ1 receptor in Tg197 hearts. Interestingly, female Tg197 mice showed a worse cardiac phenotype related to reduced T3 levels and Akt activation. T3 supplementation increased Akt activation, restored SERCA2a expression and improved cardiac function in female Tg197 mice. Conclusions TNF overexpression of Tg197 mice results in cardiac dysfunction via p38 MAPK activation and downregulation of TRβ1. Gender-specific reduction in T3 levels could cause the worse cardiac phenotype observed in female mice, while T3 administration improves cardiac function and calcium handling via modified Akt activation.

Differential inflammation-mediated function of prokineticin 2 in the synovial fibroblasts of patients with rheumatoid arthritis compared with osteoarthritis

Prokineticin 2 (PK2) is a secreted protein involved in several pathological and physiological processes, including the regulation of inflammation, sickness behaviors, and circadian rhythms. Recently, it was reported that PK2 is associated with the pathogenesis of collagen-induced arthritis in mice. However, the role of PK2 in the pathogenesis of rheumatoid arthritis (RA) or osteoarthritis (OA) remains unknown. In this study, we collected synovial tissue, plasma, synovial fluid, and synovial fibroblasts (SF) from RA and OA patients to analyze the function of PK2 using immunohistochemistry, enzyme-linked immunosorbent assays, and tissue superfusion studies. PK2 and its receptors prokineticin receptor (PKR) 1 and 2 were expressed in RA and OA synovial tissues. PKR1 expression was downregulated in RA synovial tissue compared with OA synovial tissue. The PK2 concentration was higher in RA synovial fluid than in OA synovial fluid but similar between RA and OA plasma. PK2 suppressed the production of IL-6 from TNFα-prestimulated OA-SF, and this effect was attenuated in TNFα-prestimulated RA-SF. This phenomenon was accompanied by the upregulation of PKR1 in OA-SF. This study provides a new model to explain some aspects underlying the chronicity of inflammation in RA.

Intergenerational thyroid hormone homeostasis imbalance in cerebellum of rats perinatally exposed to glyphosate-based herbicide

Agrochemicals became a public health concern due to increased human exposure and possible endocrine disruption effects in several organs, including the brain. Thyroid hormones controls neurodevelopment, which turn them sensitive to endocrine disruptors (EDs). In this work, we evaluated the effect of glyphosate-based herbicides (GBH) as an intergenerational endocrine disrupter on thyroid homeostasis in cerebellar cells. Female pregnant Wistar rats were exposed to Roundup Transorb® solution at 5 and 50 mg/kg/day, from gestation day 18 to post-natal day 5 (P5). Cerebellum of male offspring was used to evaluate gene expression. The mRNA levels of thyroid hormone receptors, hormonal conversion enzymes, hormone transporters, as well as, de novo epigenetic regulators were altered, with some of these genes presenting a non-monotonic dose response. Furthermore, metabolomic profile correlation with tested dose demonstrated altered metabolic profile, in agreement with cerebellar gene alterations. Moreover, cerebellar primary cultures exposed to non-toxic GBH concentration presented a decrease level in glial fibrillary acidic protein, a protein regulated by endocrine signals. In conclusion, our results indicate that animals exposed to non-toxic GBH doses during perinatal phase carry intergenerational alterations in key regulators of cellular thyroid hormone homeostasis and epigenetic controllers in adulthood, indicating the possible ED effect of GBH based on epigenetic alterations.

Prolactin Increases the Frequency of Follicular T Helper Cells with Enhanced IL21 Secretion and OX40 Expression in Lupus-Prone MRL/lpr Mice

Systemic lupus erythematosus is characterized by high levels of IgG class autoantibodies that contribute to the pathophysiology of the disease. The formation of these autoantibodies occurs in the germinal centers, where there is cooperation between follicular T helper cells (T_FH) and autoreactive B cells. Prolactin has been reported to exacerbate the clinical manifestations of lupus by increasing autoantibody concentrations. The objective of this study was to characterize the participation of prolactin in the differentiation and activation of T_FH cells, by performing in vivo and in vitro tests with lupus-prone mice, using flow cytometry and real-time PCR. We found that T_FH cells express the long isoform of the prolactin receptor and promoted STAT3 phosphorylation. Receptor expression was higher in MRL/lpr mice and correlative with the manifestations of the disease. Although prolactin does not intervene in the differentiation of T_FH cells, it does favor their activation by increasing the percentage of T_FH OX40⁺ and T_FH IL21⁺ cells, as well as leading to high serum concentrations of IL21. These results support a mechanism in which prolactin participates in the emergence of lupus by inducing overactive T_FH cells and perhaps promoting dysfunctional germinal centers.

Dehydroepiandrostenedione sulphate (DHEAS) levels predict high risk of rheumatoid arthritis (RA) in subclinical hypothyroidism

INTRODUCTION

The presence of rheumatism is well recognized in primary hypothyroidism. Dehydroepiandrstenedione sulphate (DHEAS) is associated with rheumatological diseases like rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). This study aims to explore relationship between joint pains and DHEAS levels in primary hypothyroidism.

METHODS

Retrospective study of 78 subjects with subclinical hypothyroidism, with TSH within reference range. The joint pains were evaluated by European Union League against rheumatism (EULAR-CSA) score and compared with serum DHEAS, RA factor, Anti-TPO antibody, highly sensitive C-recative protein (hsCRP), vitamin D levels.

RESULT

DHEAS levels <43.6 mcg/dl significantly predicted clinical features of pre RA as assessed by EULAR CSA criteria with acceptable specificity (82%). EULAR CSA score is fairly valid in assessing imminent RA in primary hypothyroidism.

CONCLUSION

Lower DHEAS predicts clinical features of imminent RA in subjects with primary hypothyroidism. This is akin to low DHEAS seen in many rheumatological disease with possibly similar mechanism. Another possibility is low DHEAS alters hepato-hypothalamo pituitary adrenal axis in presense of cytokines and induces a hitherto unrecognized state of pre rheumatoid arthritis like syndrome. Future studies on primary hypothyroidism should focus on role of lower DHEAS levels in inducing symptoms of fatigue and joint pains.

Osteoarthritis year in review: genetics, genomics, epigenetics

OBJECTIVE

In this review, we have highlighted advances in genetics, genomics and epigenetics in the field of osteoarthritis (OA) over the past year.

METHODS

A literature search was performed using PubMed and the criteria: "osteoarthritis" and one of the following terms "genetic(s), genomic(s), epigenetic(s), epigenomic(s), noncoding RNA, microRNA, long noncoding RNA, lncRNA, circular RNA, RNA sequencing, single cell sequencing, or DNA methylation between April 1, 2019 and April 30, 2020.

RESULTS

We identified 653 unique publications, many studies spanned multiple search terms. We summarized advances relating to evolutionary genetics, pain, ethnicity specific risk factors, functional studies of gene variants, and interactions between coding and non-coding RNAs in OA pathogenesis.

CONCLUSIONS

Studies have identified variants contributing to OA susceptibility, candidate biomarkers for diagnosis and prognosis, as well as promising therapeutic candidates. Validation in multiple cohorts, multi-omics strategies, and machine learning aided computational analyses have all contributed to the strength of published literature. Open access data-sets, greater sample sizes to capture broader populations and understanding disease mechanisms by investigating the interactions between multiple tissue types will further aid in progress towards understanding and curing OA.