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Background Systemic inflammation is a strong predictor of atrial fibrillation. A key role for electrical remodeling is increasingly recognized, and experimental data suggest that inflammatory cytokines can directly affect connexins resulting in gap-junction dysfunction. We hypothesized that systemic inflammation, regardless of its origin, promotes atrial electric remodeling in vivo, as a result of cytokine-mediated changes in connexin expression. Methods and Results Fifty-four patients with different inflammatory diseases and elevated C-reactive protein were prospectively enrolled, and electrocardiographic P-wave dispersion indices, cytokine levels (interleukin-6, tumor necrosis factor-α, interleukin-1, interleukin-10), and connexin expression (connexin 40, connexin 43) were measured during active disease and after reducing C-reactive protein by >75%. Moreover, peripheral blood mononuclear cells and atrial tissue specimens from an additional sample of 12 patients undergoing cardiac surgery were evaluated for atrial and circulating mRNA levels of connexins. Finally, in vitro effects of interleukin-6 on connexin expression were studied in HL-1 mouse atrial myocytes. In patients with active inflammatory diseases, P-wave dispersion indices were increased but rapidly decreased within days when C-reactive protein normalizes and interleukin-6 levels decline. In inflammatory disease patients, both P-wave dispersion indices and interleukin-6 changes were inversely associated with circulating connexin levels, and a positive correlation between connexin expression in peripheral blood mononuclear cells and atrial tissue was demonstrated. Moreover, interleukin-6 significantly reduced connexin expression in HL-1 cells. Conclusions Our data suggest that regardless of specific etiology and organ localization, systemic inflammation, via interleukin-6 elevation, rapidly induces atrial electrical remodeling by down-regulating cardiac connexins. Although transient, these changes may significantly increase the risk for atrial fibrillation and related complications during active inflammatory processes.

Increased proinflammatory interleukin-6 (IL-6) levels are associated with acquired long QT-syndrome (LQTS) in patients with systemic inflammation, leading to higher risks for life-threatening polymorphic ventricular tachycardia such as Torsades de Pointes. However, the functional and molecular mechanisms of this association are not known. In most cases of acquired LQTS, the target ion channel is the human ether-á-go-go-related gene (hERG) encoding the rapid component of the delayed rectifier K current, IKr, which plays a critical role in cardiac repolarization. Here, we tested the hypothesis that IL-6 may cause QT prolongation by suppressing IKr. Electrophysiological and biochemical assays were used to assess the impact of IL-6 on the functional expression of IKr in HEK293 cells and adult guinea-pig ventricular myocytes (AGPVM). In HEK293 cells, IL-6 alone or in combination with the soluble IL-6 receptor (IL-6R), produced a significant depression of IKr peak and tail current densities. Block of IL-6R or Janus kinase (JAK) reversed the inhibitory effects of IL-6 on IKr. In AGPVM, IL-6 prolonged action potential duration (APD) which was further prolonged in the presence of IL-6R. Similar to heterologous cells, IL-6 reduced endogenous guinea pig ERG channel mRNA and protein expression. The data are first to demonstrate that IL-6 inhibition of IKr and the resulting prolongation of APD is mediated via IL-6R and JAK pathway activation and forms the basis for the observed clinical QT interval prolongation. These novel findings may guide the development of targeted anti-arrhythmic therapeutic interventions in patients with LQTS and inflammatory disorders., Competing Interests: The authors have declared that no competing interests exist.

Objective: Increasing evidence indicates systemic inflammation as a new potential cause of acquired long QT syndrome (LQTS), via cytokine-mediated changes in cardiomyocyte ion channels. Torsade de pointes (TdP) is a life-threatening polymorphic ventricular tachycardia occurring in patients with LQTS, usually when multiple QT-prolonging factors are simultaneously present. Since classical risk factors cannot fully explain TdP events in a number of patients, we hypothesised that systemic inflammation may represent a currently overlooked risk factor contributing to TdP development in the general population., Methods: Forty consecutive patients who experienced TdP (TdP cohort) were consecutively enrolled and circulating levels of C-reactive protein (CRP) and proinflammatory cytokines (interleukin-6 (IL-6), tumour necrosis factor alpha (TNFα), interleukin-1 (IL-1)) were compared with patients with active rheumatoid arthritis (RA), comorbidity or healthy controls. An additional 46 patients with different inflammatory conditions (acute infections, n=31; immune-mediated diseases, n=12; others, n=3) and elevated CRP (inflammatory cohort) were prospectively enrolled, and corrected QT (QTc) and cytokine levels were measured during active disease and after a CRP decrease of >75% subsequent to therapy., Results: In the TdP cohort, 80% of patients showed elevated CRP levels (median: ~3 mg/dL), with a definite inflammatory disease identifiable in 18/40 cases (acute infections, n=12; immune-mediated diseases, n=5; others, n=1). In these subjects, IL-6, but not TNFα and IL-1, was ~15-20 times higher than in controls, and comparable to RA patients. In the inflammatory cohort, where QTc prolongation was common (mean values: 456.6±30.9 ms), CRP reduction was associated with IL-6 level decrease and significant QTc shortening (-22.3 ms)., Conclusion: The data are first to show that systemic inflammation via elevated IL-6 levels may represent a novel QT-prolonging risk factor contributing to TdP occurrence in the presence of other classical risk factors. If confirmed, this could open new avenues in antiarrhythmic therapy., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease primarily affecting synovial joints and is characterized by persistent high-grade systemic inflammation. Proinflammatory cytokines, particularly interleukin-6 (IL-6), are of crucial importance in the pathogenesis of the disease, driving both joint inflammation and extra-articular comorbidities. Tocilizumab, a humanized IL-6 receptor-inhibiting monoclonal antibody, has been the first, and, to date, the only, IL-6 inhibitor approved for the treatment of RA. Many studies have demonstrated the potency and effectiveness of tocilizumab in controlling disease activity and radiological progression of RA. These successful results have encouraged the development of novel IL-6 inhibitors, among which a promising agent is sirukumab (SRK), a human anti-IL-6 monoclonal antibody currently under evaluation in Phase II/III studies in patients with RA, systemic lupus erythematosus, giant-cell arteritis, and major depressive disorder. The evidence to date indicates SRK as an effective and well-tolerated new therapeutic tool for patients with active RA, with some preliminary data suggesting a specific beneficial impact on relevant systemic complications associated with the disease, such as depression and cardiovascular disease. Conversely, although pathophysiological considerations make plausible the hypothesis that IL-6 blockade with SRK may also be beneficial in the treatment of many diseases other than RA (either autoimmune or not), available clinical data in patients with systemic lupus erythematosus do not seem to support this view, also giving rise to potentially relevant concerns about drug safety. If large Phase III clinical trials currently in progress in patients with RA confirm the efficacy and tolerability of SRK, then in the long term, this drug could, in the near future, occupy a place in the treatment of the disease, potentially also opening the doors to a more extended use of SRK in a wide range of disorders in which IL-6 plays a key pathogenic role.

Objective: Experimental and clinical data suggest that statins may protect bone by inhibiting bone resorption and/or stimulating bone formation. Interleukin-6 (IL-6) is produced by osteoblasts, and potently stimulates osteoclast activation playing a key role in normal bone resorption as well as in post-menopausal and inflammation-driven osteoporosis. Although statins inhibit IL-6 production from different cell types, currently no data exist on osteoblasts. The aim of the study was to evaluate the effect of rosuvastatin on IL-6 production by human osteoblasts., Methods: Osteoblasts from osteoarthritic patients were incubated with rosuvastatin (0.1-10 μmol/L)±IL-1β, and IL-6 production was evaluated as cytokine concentration in the culture medium (ELISA), as well as mRNA expression in the cells (qPCR). Putative intracellular mechanisms of the drug, such as blocking HMG-CoA-reductase, and interference in the prenylation process were investigated by the addition of mevalonate and isoprenoids. The effect of rosuvastatin±IL-1β on the anti-resorptive molecule osteoprotegerin (OPG) was also assessed (ELISA)., Results: Rosuvastatin significantly reduced IL-6 levels in the osteoblast culture medium, both in unstimulated and IL-1β-stimulated cells. This effect was reversed by mevalonate or geranylgeraniol, but not farnesol. Moreover, the drug decreased both spontaneous and IL-1β-induced IL-6 mRNA expression in osteoblasts. Conversely, rosuvastatin did not affect OPG levels in the culture medium., Conclusion: Our results show that rosuvastatin decreases IL-6 production by osteoblasts, thereby suggesting a possible inhibiting activity on osteoclast function in an indirect way. These data may provide further rationale for employing rosuvastatin to beneficially affect bone metabolism in post-menopausal women and possibly in inflammation-driven osteoporosis., (Copyright © 2012 Société française de rhumatologie. Published by Elsevier SAS. All rights reserved.)

Objectives: Recent studies demonstrated in vivo the effectiveness of statins in reducing the inflammatory response in rheumatic diseases, and still more recently, simvastatin has been reported to inhibit in vitro IL-6 and IL-8 production by unstimulated fibroblast-like-synoviocytes (FLS) from rheumatoid arthritis (RA) patients. However, no data are available on the effect of statins on the production of these cytokines induced by IL-1, which plays a crucial role in joint inflammation in the course of active RA in vivo., Methods: In 12 RA patients, synovial tissue specimens were taken to obtain cultures of FLS. Cultures were incubated with IL-1 +/- simvastatin (5-50 micromol/l), and IL-6 and IL-8 production was evaluated (ELISA), also following the addition of mevalonate and its isoprenoid derivatives. Moreover, nuclear factor-kB (NF-kB) activation (immunocytochemistry and Western Blot analysis) were also evaluated., Results: Culture incubation with IL-1 produced a dramatic increase (up to 40-fold) in cytokine production with respect to unstimulated cells. Simvastatin significantly inhibited (about 20%) IL-6 and IL-8 production from IL-1-stimulated FLS. This effect was completely reverted by the concomitant incubation with mevalonate or geranylgeraniol (but not farnesol or squalene). Moreover, simvastatin produced a clear-cut inhibition of IL-1-induced NF-kB activation., Conclusion: Simvastatin significantly inhibits the production of IL-6 and IL-8 also in IL-1-stimulated FLS, even though to a lesser extent than in unstimulated cells, via a HMG-CoA-reductase block with an interference in prenylation process and NF-kB activation. Our results further support the rationale for the use of statins in the treatment of rheumatoid synovitis.

Objective: Hyperhomocysteinemia is commonly observed in Rheumatoid Arthritis (RA) patients, thus putatively accounting in part for the high rate of cardiovascular events in these subjects. Homocysteine (Hcy) is known to exert a pro-inflammatory effect putatively contributing to the progression of atherosclerotic lesions by cytokine production from several vascular cell-types. In order to evaluate the possibility that Hcy may play a direct pro-inflammatory activity also in the joints of RA patients, we investigated: (i) the joint concentration of Hcy, and (ii) the effect of Hcy on cytokine production by unstimulated and IL-1beta-stimulated human RA cultured synoviocytes., Methods: In 5 RA and 5 controls subjects, Hcy was measured in the blood and knee synovial fluid, and specimens of synovial tissue were taken to obtain cell cultures. Cultures were incubated with Hcy (10-100 micromol/l) +/- IL-1beta, and IL-6 and IL-8 concentrations were evaluated in the supernatants (ELISA) together with the activation of nuclear factor-kB (NF-kB) (immunocytochemistry)., Results: Hcy was present in synovial fluids, with a mean concentration significantly higher in RA patients than in controls (9.0 +/- 1.1 vs 5.9 +/- 1.2 micromol/l). Hcy enhanced IL-6 and IL-8 production in RA synoviocytes only (up to 35%). Moreover, Hcy produced a clear-cut activation of NF-kB in rheumatoid cells only., Conclusion: Hcy enhances IL-1-dependent cytokine production by rheumatoid synoviocytes at a concentration measurable in RA joints in vivo. Thus, in RA patients, Hcy may not only represent an important risk factor for the progression of cardiovascular diseases, but it may also contribute to the joint damage.