William Bradham

Tumor necrosis factor-alpha and myocardial remodeling in progression of heart failure: a current perspective

A milestone in the progression of congestive heart failure (CHF) is myocardial remodeling. Left ventricular (LV) remodeling during the progression of CHF is accompanied by changes in the structure of the myocardial extracellular matrix. Recent clinical and experimental studies have noted that increased release of tumor necrosis factor alpha (TNF-alpha) can contribute to LV myocardial remodeling. Experimental studies have noted that the induction of TNF-alpha can result in LV dilation and proceed to LV pump dysfunction. The biological effects of TNF-alpha are mediated through TNF receptors that are present on all nucleated cells in the heart. TNF receptor activation can induce a number of cellular and molecular events which contribute to LV remodeling in CHF, and include changes in myocyte size and viability and alterations in myocardial structure/composition. In vitro studies have demonstrated that TNF receptor activation can cause the induction of a proteolytic system. This proteolytic system, the matrix metalloproteinases (MMPs), is upregulated in models of LV dysfunction and possesses the capacity to degrade a wide variety of extracellular matrix components. Therefore, one pathway by which TNF-alpha can influence LV myocardial remodeling is through the induction of a specific portfolio of MMP species. Future basic and clinical studies which directly alter TNF receptor activity and measure myocardial MMP species and the relation to LV remodeling will provide new insight into this disease process and future therapeutic modalities.

Genetic Deficiency of Plasminogen Activator Inhibitor-1 Promotes Cardiac Fibrosis in Aged Mice Involvement of Constitutive Transforming Growth Factor-β Signaling and Endothelial-to-Mesenchymal Transition

Background— Elevated levels of plasminogen activator inhibitor-1 (PAI-1), a potent inhibitor of urokinase plasminogen activator and tissue plasminogen activator, are implicated in the pathogenesis of tissue fibrosis. Paradoxically, lack of PAI-1 in the heart is associated with the development of cardiac fibrosis in aged mice. However, the molecular basis of cardiac fibrosis in aged PAI-1-deficient mice is unknown. Here, we investigated the molecular and cellular bases of myocardial fibrosis. Methods and Results— Histological evaluation of myocardial tissues derived from aged PAI-1-deficient mice revealed myocardial fibrosis resulting from excessive accumulation of collagen. Immunohistochemical characterization revealed that the levels of matrix metalloproteinase-2, matrix metalloproteinase-9, and transforming growth factor-&bgr;1/2 and the number of Mac3-positive and fibroblast specific protein-1-positive cells were significantly elevated in aged PAI-1-deficient myocardial tissues compared with controls. Zymographic analysis revealed that matrix metalloproteinase-2 enzymatic activity was elevated in PAI-1-deficient mouse cardiac endothelial cells. Real-time quantitative polymerase chain reaction analyses of RNA from myocardial tissues revealed the upregulation of profibrotic markers in aged PAI-1-deficient mice. The numbers of phosphorylated Smad2–, phosphorylated Smad3–, and phosphorylated ERK1/2 MAPK-, but not pAkt/PKB-, positive cells were significantly increased in PAI-1-deficient myocardial tissues. Western blot and immunocytochemical analysis revealed that PAI-1-deficient mouse cardiac endothelial cells were more susceptible to endothelial-to-mesenchymal transition in response to transforming growth factor-&bgr;2. Conclusions— These results indicate that spontaneous activation of both Smad and non-Smad transforming growth factor-&bgr; signaling may contribute to profibrotic responses in aged PAI-1-deficient mice hearts and establish a possible link between endothelial-to-mesenchymal transition and cardiac fibrosis in PAI-1-deficient mice.

Transgenic overexpression of plasminogen activator inhibitor-1 promotes the development of polycystic ovarian changes in female mice

Reproductive age women (5-10%) are affected by the polycystic ovarian syndrome (PCOS), a diagnosis which confers lifelong cardiovascular and reproductive health implications. Plasminogen activator inhibitor-1 (PAI-1), the main physiological inhibitor of plasminogen activation, is consistently elevated in women with PCOS, regardless of metabolic status. Interestingly, the plasminogen system has long been implicated in proteolytic processes within the dynamic ovary. A non-physiologic elevation in PAI-1 may thus contribute systemically to endothelial dysfunction and locally to abnormal ovarian phenotype and function. We herein characterize the phenotypic alterations in ovaries from transgenic mice, which constitutively express a stable form of human PAI-1 and determine the plasma testosterone level in these mice as opposed to their unaffected counterparts. Over half of the ovaries from transgenic mice were found to contain large cystic structures, in contrast to wild-type controls of the same genetic background (53% (N = 17) vs 5% (N = 22); P = 0.001). Plasma testosterone was nearly twofold elevated in transgenic female mice versus wild-type females (0.312 ng/ml +/- 0.154 (N = 10) vs 0.181 ng/ml +/- 0.083 (N = 8); P = 0.014). An elevation in PAI-1 therefore appears to predispose mice to the development of this abnormal architecture, which in turn is associated with an increase in plasma testosterone. Therefore, we propose that an inappropriate elevation in PAI-1 contributes to the development of polycystic structures; these findings may thus reorient the efforts aimed at the development of therapeutic agents for the treatment of this increasingly common syndrome.

Release of matrix metalloproteinases following alcohol septal ablation in hypertrophic obstructive cardiomyopathy

OBJECTIVES This study examined plasma levels of certain matrix metalloproteinase (MMP) and tissue inhibitor of matrix metalloproteinase (TIMP) species before and after alcohol-induced myocardial infarction (MI) in patients with hypertrophic obstructive cardiomyopathy (HOCM). BACKGROUND Matrix metalloproteinases contribute to tissue remodeling, and endogenous control of MMP activity is achieved by the concordant release and binding of TIMPs. Animal models of MI have demonstrated a role for MMP activation in myocardial remodeling. However, the temporal relationship of MMP and TIMP release following a controlled myocardial injury in humans remains unknown. METHODS Plasma levels for the gelatinases MMP-2 and MMP-9, and for the collagenases MMP-8 and MMP-13, as well as TIMP-1 profiles were examined (by enzyme-linked immunosorbent assay) at baseline and serially up to 60 h following alcohol injection into the septal perforator artery in order to induce an MI in 51 patients with HOCM (age 55 +/- 2 years). RESULTS Plasma creatine kinase (MB isoform), indicating myocardial injury, increased 2,150% 18 h post-MI (p < 0.05). Plasma MMP-9 increased by over 400% and MMP-8 by over 100% from baseline values by 12 h post-MI (p < 0.05 vs. baseline). A similar temporal profile was not observed for MMP-2 and MMP-13. In addition, a concomitant increase in plasma TIMP-1 levels did not occur post-MI. As a result, MMP/TIMP stoichiometry (MMP-9/TIMP-1 ratio) increased significantly post-MI, suggestive of reduced TIMP-1 mediated MMP-9 inhibition, which would potentially enhance extracellular myocardial remodeling. CONCLUSIONS These unique results demonstrated that induction of a controlled myocardial injury in humans, specifically through alcohol-induced MI, caused species- and time-dependent perturbations of MMP/TIMP stoichiometry that would facilitate myocardial remodeling in the early post-MI setting.

High-sensitivity cardiac troponin-I is elevated in patients with rheumatoid arthritis, independent of cardiovascular risk factors and inflammation.

Objectives We examined the hypothesis that cardiac-specific troponin-I (cTn-I), a biomarker of myocardial injury, is elevated in patients with rheumatoid arthritis (RA). Background RA patients have an increased incidence of heart failure (HF). Chronic myocardial injury in RA may be a mechanism for the development of HF. Methods We compared cTn-I concentrations measured by high-sensitivity immunoassay in 164 patients with RA and 90 controls, excluding prior or active heart failure. We examined the relationship between cTn-I concentrations and cardiovascular risk factors, inflammation, and coronary artery calcium score (CACS), a measure of coronary atherosclerosis. Results cTn-I concentrations were 49% higher in patients with RA (median 1.15 pg/mL [IQR 0.73–1.92] than controls (0.77 pg/mL [0.49–1.28](P<0.001). The difference remained statistically significant after adjustment for demographic characteristics (P = 0.002), further adjustment for cardiovascular (CV) risk factors (P = 0.004), inflammatory markers (P = 0.008), and in a comprehensive model of CV risk factors and inflammatory markers (P = 0.03). In patients with RA, cTn-I concentrations were positively correlated with age (rho = 0.359), Framingham risk score (FRS) (rho = 0.366), and systolic blood pressure (rho = 0.248 (all P values ≤0.001)), but not with measures of inflammation or RA drug therapies. cTn-I was significantly correlated with CACS in RA in univariate analysis, but not after adjustment for age, race, sex and FRS (P = 0.79). Further model adjustments for renal function and coronary artery disease confirmed the significance of the findings. Conclusion High-sensitivity cTn-I concentrations are elevated in patients with RA without heart failure, independent of cardiovascular risk profile and inflammatory markers. Elevated troponin concentrations in RA may indicate subclinical, indolent myocardial injury.

Myocardial T1 Measurement Predicts Beneficial LV Remodeling After Long-Term Heart Failure Therapy

BACKGROUND The myocardial longitudinal relaxation time (T1) on cardiac magnetic resonance imaging (CMR) can quantify myocardial fibrosis in the presence or absence of visually detectable late gadolinium (Gd) enhancement (LGE). Mineralocorticoid receptor antagonist (MRA) treatment produces beneficial remodeling in nonischemic dilated cardiomyopathy (NIDCM). We assessed the hypothesis that interstitial myocardial fibrosis measured with the use of CMR predicts left ventricular (LV) beneficial remodeling in NIDCM after heart failure (HF) treatment including MRAs. METHODS AND RESULTS Twelve patients with NIDCM, on stable beta-blocker and angiotensin-converting enzyme inhibitor/angiotensin receptor-blocking therapy, were studied before and after 6-29 months of treatment with MRAs, by means of CMR assessment of LV structure, function, and T1 from standard Look-Locker sequences (T1LL). All patients had depressed cardiac function, dilated left ventricles, and no visual LGE. After adding MRA to HF treatment, the LV ejection fraction increased and the LV end-systolic volume index (LV end-systolic volume/m2) decreased in all patients (P < .0001). This this was inversely proportional to the baseline myocardial T1LL (r = -0.65; P = .02). CONCLUSION Myocardial T1LL, in the absence of visually detectable LGE, was quantitatively related to the degree of beneficial LV remodeling achieved in response to adding MRA to a HF regimen.

Absence of Fibrosis and Inflammation by Cardiac Magnetic Resonance Imaging in Rheumatoid Arthritis Patients with Low to Moderate Disease Activity

Objective. The prevalence of heart failure is increased 2-fold in patients with rheumatoid arthritis (RA); this is not explained by ischemic heart disease or other risk factors for heart failure. We hypothesized that in patients with RA without known heart disease, cardiac magnetic resonance imaging (cMRI) would detect altered cardiac structure, function, and fibrosis. Methods. We performed 1.5-T cMRI in 59 patients with RA and 56 controls frequency-matched for age, race, and sex, and compared cMRI indices of structure, function, and fibrosis [late gadolinium enhancement (LGE), native T1 mapping, and extracellular volume (ECV)] using Mann-Whitney U tests and linear regression, adjusting for age, race, and sex. Results. Most patients with RA had low to moderate disease activity [28-joint count Disease Activity Score–C-reactive protein median 3.16, interquartile range (IQR) 2.03–4.05], and 49% were receiving anti-tumor necrosis factor agents. Left ventricular (LV) mass, LV end-diastolic and -systolic volumes indexed to body surface area, and LV ejection fraction and left atrial size were not altered in RA compared to controls (all p > 0.05). Measures of fibrosis were not increased in RA: LGE was present in 2 patients with RA and 1 control subject; native T1 mapping was similar comparing RA and control subjects, and ECV (median, IQR) was lower (26.6%, 24.7–28.5%) in patients with RA compared to control subjects (27.5%, 25.4–30.4%, p = 0.03). Conclusion. cMRI measures of cardiac structure and function were not significantly altered, and measures of fibrosis were similar or lower in RA patients with low to moderate disease activity compared to a matched control group.

Timing of Left Ventricular Remodeling in Nonischemic Dilated Cardiomyopathy

Background: Mineralocorticoid receptor antagonist (MRA) treatment produces beneficial left ventricular (LV) remodeling in nonischemic dilated cardiomyopathy (NIDCM). This study addressed the timing of maximal beneficial LV remodeling in NIDCM when adding MRA. Materials and Methods: We studied 12 patients with NIDCM on stable &bgr;‐blocker and angiotensin‐converting enzyme inhibitor/angiotensin receptor‐blocking therapy who underwent cardiac magnetic resonance imaging before and after 6‐31 months of continuous MRA therapy. Results: At baseline, the LV ejection fraction (LVEF) was 24% (19‐27); median [interquartile range]. The LV end‐systolic volume index (LVESVI) was 63 ml (57‐76) and the LV stroke volume index (LVSVI) was 19 ml (14‐21), all depressed. After adding MRA to the HF regimen, the LVEF increased to 47% (42‐52), with a decrease in LVESVI to 36 ml (33‐45) and increase in LVSVI to 36 ml (28‐39) (for each, P < 0 .0001). Using generalized least squares analysis, the maximal beneficial remodeling (defined by maximal increase in LVEF, the maximal decrease in LVESVI and maximal increase in LVSVI) was achieved after approximately 12‐16 months of MRA treatment. Conclusions: Adding MRA to a standard medical regimen for NIDCM resulted in beneficial LV remodeling. The maximal beneficial remodeling was achieved with 12‐16 months of MRA therapy. These results have implications for the timing of other advanced therapies, such as placing internal cardioverter‐defibrillators.

Aortic insufficiency following transcatheter aortic valve replacement is underestimated by echocardiography compared with cardiac MRI

Background The degree of aortic insufficiency (AI) after transcatheter aortic valve replacement (TAVR) has been identified as a predictor of increased mortality. Since even mild AI is associated with increased mortality in some studies, accurate quantification of post-TAVR AI is critical. Assessment of AI by echocardiography is typically performed by visual inspection and semi-quantitative methods. Most post-TAVR AI is paravalvular, however echocardiography has limited ability to quantify multiple eccentric paravalvular jets. Using flow quantification methods, cardiac MRI (CMR) may more accurately quantify AI severity post-TAVR and therefore more accurately assess risk in this population. Methods Twenty-three patients who underwent TAVR with a SAPIEN prosthesis were studied. All patients underwent an intraoperative transesophageal echocardiogram (TEE), as well as a post-procedure transthoracic echocardiogram (TTE) and CMR. Paravalvular AI by TTE and TEE was graded using color Doppler by quantifying the circumferential extent of AI as a percentage of the aortic annulus (none 30%) following recommendations from the Valve Academic Research Consortium. AI severity by CMR was quantified as the regurgitant fraction of forward aortic flow based on previously published recommendations (none 48%). Results The mean age was 79 +/- 10 years; 52% were men. TTE and CMR were performed at 1 [1-1] and 4 [1-4] days postTAVR respectively (median [IQR]). The left ventricular ejection fraction (LVEF) by CMR was 65 +/- 10%. AI severity by TTE was none in 9 (39.1%), trace in 11 (47.8%), and mild in 3 (13%) patients. TEE identified trace central AI in 6 patients (26%). Paravalvular AI by TEE was none in 4 (17.4%), trace in 14 (60.9%), and mild in 5 (21.7%) patients. AI by CMR was none in 2 (8.7%), trace in 5 (21.7%), mild in 13 (56.5%), and moderate in 3 (13%) patients; (Figure 1). A higher proportion of patients with mild or greater AI was identified by CMR (16/23, 70%) compared to TTE (3/23, 13%) and TEE (5/23, 22%); (Figure 2). Conclusions