Objective
To determine the mechanisms of inflammation‐induced left ventricular (LV) remodeling and effects of blocking circulating tumor necrosis factor alpha (TNF‐α) in a model of systemic inflammation.
Methods
Seventy Sprague‐Dawley rats were divided into three groups: the control group, the collagen‐induced arthritis (CIA) group, and the anti‐TNF‐α group. Inflammation was induced in the CIA and anti‐TNF‐α groups. Following the onset of arthritis, the anti‐TNF‐α group received the TNF‐α inhibitor, etanercept, for 6 weeks. LV geometry and function were assessed with echocardiography. Circulating inflammatory markers were measured by ELISA and LV gene expression was assessed by comparative TaqMan® polymerase chain reaction.
Results
The LV relative gene expression of pro‐fibrotic genes, transforming growth factor β (TGFβ) (p = 0.03), collagen I (Col1) (p < 0.0001), and lysyl oxidase (LOX) (p = 0.002), was increased in the CIA group compared with controls, consistent with increased relative wall thickness (p = 0.0009). Col1 and LOX expression in the anti‐TNF‐α group were similar to controls (both, p > 0.05) and tended to be lower compared to the CIA group (p = 0.06 and p = 0.08, respectively), and may, in part, contribute to the decreased relative wall thickness in the anti‐TNF‐α group compared to the CIA group (p = 0.03). In the CIA group, the relative gene expression of matrix metalloproteinase 2 (MMP2) and MMP9 was increased compared to control (p = 0.04) and anti‐TNF‐α (p < 0.0001) groups, respectively.
Conclusion
Chronic systemic inflammation induces fibrosis and dysregulated LV extracellular matrix remodeling by increasing local cardiac pro‐fibrotic gene expression, which is partially mediated by TNF‐α. Inflammation‐induced LV diastolic dysfunction is likely independent of myocardial fibrosis.
Omentin is an adipokine that reportedly protects against cardiometabolic risk. We investigated the relationships between omentin concentrations and subclinical cardiovascular disease in rheumatoid arthritis (RA). Omentin concentrations were measured in 213 (104 black; 109 white) RA patients. Relationships of omentin levels with those of endothelial activation markers, ultrasound determined carotid intima-media thickness and plaque, and matrix metalloproteinase (MMP)-2, -3 and -9 that mediate altered plaque stability, were identified in confounder adjusted multivariate regression models. Omentin concentrations were inversely associated with MMP-3 levels [β = -364 (0.113), p = 0.002]. This relationship was influenced by population origin, RA activity and the erythrocyte sedimentation rate and joint deformity count (interaction p value = 0.009, 0.04, 0.04 and 0.007, respectively). Accordingly, the omentin-MMP-3 concentration relationship was reproduced in white [β (SE) = -0.450 (0.153), p = 0.0004)] but not black patients [β (SE) = -0.099 (0.195), p = 0.6)], in participants with disease remission or mild disease activity [β (SE) = -0.411 (0.139), p = 0.004] but not with moderate or severe RA activity [β (SE) = -0.286 (0.202), p = 0.2], and in those with a small [β (SE) = -0.534 (0.161), p = 0.001] but not large erythrocyte sedimentation rate [-0.212 (0.168), p = 0.2] and without [β (SE) = -0.554 (0.165), p = 0.0001] but not with large joint deformity counts [-0.110 (0.173), p = 0.5]. Omentin levels were unrelated to endothelial activation and atherosclerosis. Among patients with RA, a lack of plaque stabilizing effects by omentin may contribute to the reported link between severe disease and increased cardiovascular risk. The association between concentrations of omentin and MMP-3 is population specific in RA.
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