MicroRNA and interleukin 6 interplay in the adipose tissue of rheumatoid arthritis patients.

OBJECTIVES: MicroRNAs (miRs) are non-translated RNA sequences that elicit negative control over protein expression. The adipose tissue (AT) is considered the major producer of miRs and inflammatory interleukin 6 (IL-6). This study aims to investigate the relationship between production of IL-6 and miRs in AT. METHODS: IL-6 gene expression was analysed in RNA extracts from subcutaneous AT of 75 patients with rheumatoid arthritis (RA), with qPCR. Genome-wide profile of human miRs (2565 miRs, 96.6%) was analysed in 35 AT samples on 3D microarray. The miR-processing proteins Dicer, Drosha and DGCR8 were analysed with qPCR. In silico prediction of protein targets for the differentially expressed (DE) miRs (p<0.05; log2FC >±0.5) was conducted by DIANA software. Seven AT samples were stimulated in vitro with IL-6 or IL-6+IL-6R antibody tocilizumab and analysed for the miR processing proteins. RESULTS: We identified 30 DE miRs between AT with high and low IL-6 mRNA, of which 26 miRs were inversely related with IL-6 levels. DE miRs were predicted to interfere in oestrogen (p=0.001), FoxO (p=0.006) and insulin (p=0.03) signalling pathways. High expression of IL-6 in AT was associated with significantly higher expression of Dicer (p=0.04) and Drosha (p=0.04), while inhibition of IL-6 signalling with tocilizumab decreased the levels of total miRs processing enzymes (p=0.003). CONCLUSIONS: IL-6 mRNA production in AT has a negative effect on the miRs expression profile and it increases miR-production capacity.

Low serum IGF1 is associated with hypertension and predicts early cardiovascular events in women with rheumatoid arthritis.

OBJECTIVES: Since low insulin-like growth factor (IGF) 1 is often linked to inflammation, we analyze whether serum levels of IGF1 are associated with cardiovascular disease (CVD) in rheumatoid arthritis (RA) in a longitudinal observational study. METHODS: A CVD risk was estimated (eCVR) in 184 female RA patients (mean age 52 years) and in 132 female patients after ischemic stroke (mean age 56 years) with no rheumatic disease, using the Framingham algorithm. The median level of IGF1 divided the cohorts in IGF1high and IGF1low groups. A 5-year prospective follow-up for new CVD events was completed in all RA patients. The Mantel-Cox analysis and event-free survival curves were prepared. Unsupervised clustering of proteins within the IGF1 signaling pathway was employed to identify their association with eCVR. RESULTS: Low IGF1 resulted in a higher eCVR in RA patients (7.2% and 3.3%, p = 0.0063) and in stroke (9.3% and 7.1%, p = 0.033). RA had higher rate for new CVD events at prospective follow-up (OR 4.96, p = 0.028). Hypertension was the major risk factor associated with low IGF1 in RA and stroke. In hypertension, IGF1 was no longer responsible for intracellular activation and lost its correlation to IRS1/2 adaptor proteins. The clustering analysis confirmed that combination of low IGF1 and IRS1/2 with high IL6, insulin, and glucose predisposed to high eCVR and emphasized the functional role of serum IGF1. CONCLUSIONS: Low serum IGF1 precedes and predicts development of early CVD events in female RA patients. Hypertension and aberrant IGF1 receptor signaling are highlighted as the important contributors to IGF1-related CVD events.

IGF-1R signalling contributes to IL-6 production and T cell dependent inflammation in rheumatoid arthritis.

BACKGROUND: Signalling through insulin-like growth factor 1 receptor (IGF-1R) is essential for cell survival, but may turn pathogenic in uncontrolled tissue growth in tumours. In rheumatoid arthritis (RA), the IGF-1R signalling is activated and supports expansion of the inflamed synovia. AIM: In the present study, we assess if disruption of IGF-1R signalling resolves arthritis. MATERIAL AND METHODS: Clinical associations of IGF-1R expression in leukocytes of the peripheral blood were studied in 84 RA patients. Consequences of the IGF-1R signalling inhibition for arthritis were studied in mBSA immunised Balb/c mice treated with NT157 compound promoting degradation of insulin receptor substrates. RESULTS: In RA patients, high expression of IGF-1R in leukocytes was associated with systemic inflammation as verified by higher expression of NF-kB, serum levels of IL6 and erythrocyte sedimentation rate, and higher pain perception. Additionally, phosphorylated IGF-1R and STAT3 enriched T cells infiltrate in RA synovia. Treatment with NT157 inhibited the phosphorylation of IGF-1R and STAT3 in synovia, and alleviated arthritis and joint damage in mice. It also reduced expression of IGF-1R and despaired ERK and Akt signalling in spleen T cells. This limited IL-6 production, changed RoRgt/FoxP3 balance and IL17 levels. CONCLUSION: IGF-1R signalling contributes to T cell dependent inflammation in arthritis. Inhibition of IGF-1R on the level of insulin receptor substrates alleviates arthritis by restricting IL6-dependent formation of Th17 cells and may open for new treatment strategies in RA.

High Expression of STAT3 in Subcutaneous Adipose Tissue Associates with Cardiovascular Risk in Women with Rheumatoid Arthritis.

Despite the predominance of female patients and uncommon obesity, rheumatoid arthritis (RA) is tightly connected to increased cardiovascular morbidity. The aim of this study was to investigate transcriptional activity in the subcutaneous white adipose tissue (WAT) with respect to this disproportionate cardiovascular risk (CVR) in RA. CVR was estimated in 182 female patients, using the modified Systematic Coronary Risk Evaluation scale, and identified 93 patients with increased CVR. The overall transcriptional activity in WAT was significantly higher in patients with CVR and was presented by higher serum levels of WAT products leptin, resistin and IL-6 (all, p < 0.001). CVR was associated with high WAT-specific transcription of the signal transducer and activator of transcription 3 (STAT3) and the nuclear factor NF-kappa-B p65 subunit (RELA), and with high transcription of serine-threonine kinase B (AKT1) in leukocytes. These findings suggest Interleukin 6 (IL-6) and leptin take part in WAT-specific activation of STAT3. The binary logistic regression analysis confirmed an independent association of CVR with IL-6 in serum, and with STAT3 in WAT. The study shows an association of CVR with transcriptional activity in WAT in female RA patients. It also emphasizes the importance of STAT3 regulatory circuits for WAT-related CVR in RA.

Impact of the Uncoupling Protein 1 on Cardiovascular Risk in Patients with Rheumatoid Arthritis.

Adiposity is strongly associated with cardiovascular (CV) morbidity. Uncoupling protein 1 (UCP1) increases energy expenditure in adipocytes and may counteract adiposity. Our objective was to investigate a connection between UCP1 expression and cardiovascular health in patients with rheumatoid arthritis (RA) in a longitudinal observational study. Transcription of UCP1 was measured by qPCR in the subcutaneous adipose tissue of 125 female RA patients and analyzed with respect to clinical parameters and the estimated CV risk. Development of new CV events and diabetes mellitus was followed for five years. Transcription of UCP1 was identified in 89 (71%) patients. UCP1 positive patients had often active RA disease (p = 0.017), high serum levels of IL6 (p = 0.0025) and were frequently overweight (p = 0.015). IL-6hiBMIhi patients and patients treated with IL6 receptor inhibitor tocilizumab had significantly higher levels of UCP1 compared to other RA patients (p < 0.0001, p = 0.032, respectively). Both UCP1hi groups displayed unfavorable metabolic profiles with high plasma glucose levels and high triglyceride-to-HDL ratios, which indicated insulin resistance. Prospective follow-up revealed no significant difference in the incidence of new CV and metabolic events in the UCP1hi groups and remaining RA patients. The study shows that high transcription of UCP1 in adipose tissue is related to IL6-driven processes and reflects primarily metabolic CV risk in female RA patients.

Low Soluble Receptor for Advanced Glycation End Products Precedes and Predicts Cardiometabolic Events in Women With Rheumatoid Arthritis.

Background: Cardiovascular disease (CVD) causes premature mortality in rheumatoid arthritis (RA). Levels of soluble (s)RAGE change with aging, hypertension and hypercholesterolemia. We assessed whether sRAGE was associated with increased risk of CVD in RA patients. Methods: Serum sRAGE was measured in 184 female RA patients and analyzed with respect to CVD risk estimated by the Framingham algorithm (eCVR), metabolic profile and inflammation. Levels of sRAGE in 13 patients with known cardio-metabolic morbidity defined the cut-off for low sRAGE. Prospective 5-year follow-up of new CV and metabolic events was completed. Results: Low sRAGE was significantly associated with previous history and with new imminent cardiometabolic events in the prospective follow-up of RA patients. In both cases, low sRAGE reflected higher estimation of CVR in those patients. Low sRAGE was attributed to adverse metabolic parameters including high fasting plasma glucose and body fat content rather than inflammation. The association of sRAGE and poor metabolic profile was prominent in patients younger than 50 years. Conclusions: This study points at low sRAGE as a marker of metabolic failure developed during chronic inflammation. It highlights the importance for monitoring metabolic health in female RA patients for timely prevention of CVD. Trial registration: ClinicalTrials.gov with ID NCT03449589. Registered 28, February 2018.