Cardiac cytokine therapy? Relevance of targeting inflammatory mediators to combat cardiac arrhythmogenic remodeling

Pilot study of peripheral blood chemokines as biomarkers for atrial fibrillation-related thromboembolism and bleeding in elderly patients

Background

The scoring systems currently used to identify the potential for thrombosis and bleeding events in high-risk atrial fibrillation patients have certain limitations. The aim of this pilot study was to identify inflammatory chemokines with potential utility as sensitive biomarkers for the risk of thrombosis and bleeding in elderly patients with non-valvular atrial fibrillation.

Methods

From January 1, 2014, to December 31, 2017, 200 consecutive elderly patients with atrial fibrillation (average age: 87.6 ± 7.7 years) were enrolled and followed up for 2 years to observe thromboembolic (arterial and venous) and bleeding events. Serum was collected upon enrollment, and the baseline levels of 27 chemokines were analyzed. During the 2-year follow-up, 12 patients were lost to follow-up. Among the 188 patients, there were 32 cases (17.0%) of AF-related thrombosis, 36 cases (19.1%) of arterial thrombosis, and 35 cases (18.6%) of major bleeding events.

Results

Among 188 patients, 30 patients without clinical events (control group), 23 with arterial thrombosis, 15 with atrial fibrillation-related venous thromboembolism, and 12 with major bleeding were selected and randomly matched to compare chemokine levels. The baseline levels of interleukin-6, interleukin-10, vascular cell adhesion molecule-1, chemokine C-C-motif ligand, B-lymphocyte chemoattractant 1, interleukin-4, E-selectin, fractalkine, C-X-C motif chemokine 12, and granulocyte chemotactic protein 2 were found to differ statistically among the four groups (p < 0.05). Compared with that in the control group, the level of interleukin-4 in patients with atrial fibrillation-related thrombosis, arterial thrombosis, or major bleeding increased by 53-fold (0.53 vs. 0.01 pg/ml), 17-fold (0.17 vs. 0.01 pg/ml), and 19-fold (0.19 vs. 0.01 pg/ml), respectively. Compared with that in the control group, the level of interleukin-6 in patients with arterial thrombosis increased by six-fold (39.78 vs. 4.98 pg/ml).

Conclusions

Among elderly patients with atrial fibrillation at high risk of thromboembolism and bleeding, the baseline levels of interleukin-6, interleukin-4, and E-selectin were significantly increased in those that experienced thrombosis and bleeding events during the 2-year follow-up, indicating that these chemokines may serve as potential biomarkers for an increased risk of thrombosis and bleeding in this population.

Clinical trial registration number

ChiCTR-OCH-13003479.

Evidence of Failed Resolution Mechanisms in Arrhythmogenic Inflammation, Fibrosis and Right Heart Disease

Inflammation is a complex program of active processes characterized by the well-orchestrated succession of an initiation and a resolution phase aiming to promote homeostasis. When the resolution of inflammation fails, the tissue undergoes an unresolved inflammatory status which, if it remains uncontrolled, can lead to chronic inflammatory disorders due to aggravation of structural damages, development of a fibrous area, and loss of function. Various human conditions show a typical unresolved inflammatory profile. Inflammatory diseases include cancer, neurodegenerative disease, asthma, right heart disease, atherosclerosis, myocardial infarction, or atrial fibrillation. New evidence has started to emerge on the role, including pro-resolution involvement of chemical mediators in the acute phase of inflammation. Although flourishing knowledge is available about the role of specialized pro-resolving mediators in neurodegenerative diseases, atherosclerosis, obesity, or hepatic fibrosis, little is known about their efficacy to combat inflammation-associated arrhythmogenic cardiac disorders. It has been shown that resolvins, including RvD1, RvE1, or Mar1, are bioactive mediators of resolution. Resolvins can stop neutrophil activation and infiltration, stimulate monocytes polarization into anti-inflammatory-M2-macrophages, and activate macrophage phagocytosis of inflammation-debris and neutrophils to promote efferocytosis and clearance. This review aims to discuss the paradigm of failed-resolution mechanisms (FRM) potentially promoting arrhythmogenicity in right heart disease-induced inflammatory status.

Resolution-promoting autacoids demonstrate promising cardioprotective effects against heart diseases

Abstract

Chronic heart diseases have in common an unresolved inflammatory status. In atherosclerosis, myocarditis, myocardial infarction, or atrial fibrillation, mounting evidence suggests that unresolved inflammation contributes to the chronicity, aggravation, and morbidity of the disease. Following cardiac injury or infection, acute inflammation is a normal and required process to repair damaged tissues or eliminate pathogens and promote restoration of normal functions and structures. However, if acute inflammation is not followed by resolution, a chronic and deleterious inflammatory status may occur, characterized by the persistence of inflammatory biomarkers, promoting aggravation of myocardial pathogenesis, abnormal structural remodeling, development of cardiac fibrosis, and loss of function. Although traditional antiinflammatory strategies, including the use of COX-inhibitors, to inhibit the production of inflammation promotors failed to promote homeostasis, mounting evidence suggests that activation of specific endogenous autacoids may promote resolution and perpetuate cardioprotective effects. The recent discovery of the active mechanism of resolution suggests that proresolving signals and cellular processes may help to terminate inflammation and combat the development of its chronic profile in cardiac diseases. This review discussed (I) the preclinical and clinical evidence of inflammation-resolution in cardiac disorders including atrial fibrillation; (II) how and why many traditional antiinflammatory treatments failed to prevent or cure cardiac inflammation and fibrosis; and (III) whether new therapeutic strategies may interact with the resolution machinery to have cardioprotective effects.

Graphical abstract

RvD D-series resolving, RvE E-series resolving, LXA4 lipoxin A4, MaR1 maresin-1