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Am J Physiol Heart Circ Physiol 293: H743-H753, 2007. First published April 6, 2007; doi:10.1152/ajpheart.00166.2007
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Tumor necrosis factor-{alpha} is toxic via receptor 1 and protective via receptor 2 in a murine model of myocardial infarction

Yoshiya Monden,1 Toru Kubota,1 Takahiro Inoue,1 Takaki Tsutsumi,1 Shunichi Kawano,1 Tomomi Ide,1 Hiroyuki Tsutsui,2 and Kenji Sunagawa1

1Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka; and 2Department of Cardiovascular Medicine, Hokkaido University Graduate School of Medicine, Sapporo, Japan

Submitted 8 February 2007 ; accepted in final form 3 April 2007


   ABSTRACT
TOP
 ABSTRACT
MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Tumor necrosis factor (TNF)-{alpha} induced in damaged myocardium has been considered to be cardiotoxic. TNF-{alpha} initiates its biological effects by binding two distinct receptors: R1 (p55) and R2 (p75). Although TNF-{alpha} has been shown to be cardiotoxic via R1-mediated pathways, little is known about the roles of R2-mediated pathways in myocardial infarction (MI). We created MI in R1 knockout (R1KO), R2KO, and wild-type (WT) mice by ligating the left coronary artery. Functional, histological, and biochemical analyses were performed 4 wk after ligation. Although infarct size was not different among WT, R1KO, and R2KO mice, post-MI survival was significantly improved in R1KO but not R2KO mice. R1KO significantly ameliorated contractile dysfunction after MI, whereas R2KO significantly exaggerated ventricular dilatation and dysfunction. Myocyte hypertrophy and interstitial fibrosis in noninfarct myocardium was exacerbated in R2KO but not in R1KO mice. Expression of R1, which was not affected by MI and was nullified in R1KO mice, was significantly upregulated in R2KO mice. In contrast, expression of R2, which was significantly upregulated by MI and was nullified in R2KO mice, was unaffected in R1KO mice. Meanwhile, TNF-{alpha} expression, which was significantly upregulated in noninfarct myocardium after MI, was not affected by R1KO or R2KO. However, transcript levels of IL-6, IL-1beta, transforming growth factor-beta, and monocyte chemotactic protein-1, which were significantly upregulated after MI, were significantly downregulated in R1KO mice. In contrast, transcript levels of IL-6 and IL-1beta were significantly further upregulated in R2KO mice. TNF-{alpha} is toxic via R1 and protective via R2 in a murine model of MI. Selective blockade of R1 may be a candidate therapeutic intervention for MI.

cytokines; heart failure; remodeling; interstitial fibrosis

TUMOR NECROSIS FACTOR-{alpha} (TNF-{alpha}) is a proinflammatory cytokine that exerts a wide range of biological activities (33). TNF-{alpha} is induced in the failing human heart (30) and has been considered to be cardiotoxic, because in vitro studies have shown that TNF-{alpha} suppresses cardiac contractility (6), provokes myocardial hypertrophy (35), and induces apoptosis in cardiac myocytes (16). It also has direct effects on the matrix and collagen framework and is a potential major contributor to cardiac remodeling (5, 20). However, in anti-cytokine clinical trials, the use of either a soluble TNF receptor (RENEWAL; Ref. 21) or an anti-TNF antibody (ATTACH; Ref. 4) was not beneficial to patients with heart failure. In addition, our previous study (22) indicated that treatment with soluble TNF receptors significantly exacerbated ventricular dysfunction and remodeling with enhanced interstitial fibrosis after myocardial infarction (MI). These findings suggest that TNF-{alpha} may not be exclusively toxic but may be partially protective in cardiovascular diseases.

TNF-{alpha} initiates its biological effects by binding two distinct cell surface receptors with approximate molecular masses of 55 (TNFR1) and 75 kDa (TNFR2) (33). Both receptors are expressed in most cell types, including cardiac myocytes. The cytoplasmic domains of TNFR1 and TNFR2 are different (23), and the two receptors activate both distinct and overlapping intracellular signal pathways (29). Although most biological activities of TNF-{alpha} are signaled through TNFR1, the role of TNFR2 remains unclear. Therefore, the present study was designed to assess the pathophysiological role of these receptors in the process of infarct healing and cardiac remodeling after MI, using TNFR1 knockout (KO) and TNFR2 KO mice to block TNFR1- and TNFR2-mediated pathways, respectively. Our results indicate that inhibition of TNFR1-mediated pathways attenuated ventricular dysfunction and improved post-MI survival. In contrast, inhibition of TNFR2-mediated pathways exacerbated ventricular dysfunction and remodeling with upregulation of TNFR1 in noninfarct myocardium. These results support the hypothesis that TNF-{alpha} plays a protective role in MI via TNFR2-mediated pathways. Therefore, selective blockade of TNFR1 may be a desirable therapeutic intervention for MI.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 
Animal model. A total of 396 C57BL/6 mice [130 with targeted deletion of TNFR1 (R1KO), 134 with targeted deletion of TNFR2 (R2KO), and 132 wild type (WT)] obtained from Jackson Laboratories (Bar Harbor, ME) were used in the present study. This study was reviewed by the Committee of the Ethics on Animal Experiment, Kyushu University Graduate School of Medical Sciences, and carried out in accordance with the Guideline for Animal Experiment, Kyushu University, and the Law (No. 105) and Notification (No. 6) of the Government. The investigation conforms with the "Guide for the Care and Use of Laboratory Animals" published by the U.S. National Institutes of Health [DHEW Publication No. (NIH) 85-23, Revised 1996, Office of Science and Health Reports, DRR/NIH, Bethesda, MD 20205].

We created MI in male WT, R1KO, and R2KO mice (8–10 wk old and 21–26 g in weight) by ligating the left coronary artery as reported previously (8, 9, 13). Sham operation without coronary artery ligation was also performed. During the study period of 4 wk, cages were inspected daily for animals that had died. All dead mice were examined for the presence of pleural effusion and cardiac rupture as well as MI. The effects of TNF-{alpha} blockade on ventricular remodeling were examined on days 3 and 28 (4 wk) after MI. Animals that died within 12 h of surgery (~17–20%) were excluded from the study because surgical error could not be excluded as the cause of death.

Echocardiographic and hemodynamic measurements. Echocardiographic studies were performed using an ultrasonograph system (SSD-5500; ALOKA, Tokyo, Japan) as previously described (8, 9, 13). A mouse was anesthetized with 2.5% Avertin (14 µl/g body wt ip; Aldrich Chemical) and placed in a supine position. A 10-MHz transducer (ALOKA) was applied to the left hemithorax. A two-dimensional targeted M-mode image was obtained from the short-axis view at the level of the greatest left ventricular (LV) dimension. On day 3, arterial blood pressure and heart rate were also measured in awake animals with the use of a noninvasive tail-cuff system (BP-98A; Softron). On day 28, a 1.4-Fr micromanometer-tipped catheter (Millar) was inserted into LV through the right carotid artery to measure LV pressure (8, 9, 13).

Infarct size and pathological analysis. After body weight and heart weight were measured, tissues were fixed in 10% neutral buffered formalin for hematoxylin and eosin staining or snap frozen in liquid nitrogen for RNA and protein analysis. Infarct sizes in mice were determined using methods described previously (8, 9, 13). Briefly, the whole LV from apex to base was cut into four transverse sections. Infarct length was measured along the endocardial and epicardial surfaces from each of the LV sections, and the values from all specimens were summed. Total LV circumference was calculated as the sum of endocardial and epicardial segment lengths from all LV sections. Infarct size (in percent) was calculated as total infarct circumference divided by total LV circumference.

After hematoxylin and eosin staining, cross-sectional area of cardiomyocytes in the left ventricle was evaluated as previously reported (9, 13). The outline of 100–200 myocytes was traced in each section, and NIH Image software was used to determine myocyte cross-sectional area. Picrosirius red staining was performed to observe interstitial collagen fibers and determine collagen volume fraction (9, 13). Collagen volume fraction was measured at six fields for each heart.

RNase protection assay. To determine the myocardial gene expression of TNFR1, TNFR2, and TNF-{alpha} as well as other proinflammatory cytokines, we performed multiprobe RNase protection assays (RPA) (RiboQuant; PharMingen) according to the manufacture's protocol by using a custom template set containing probes for murine TNFR1, TNFR2, TNF-{alpha}, IL-6, IL-1beta, transforming growth factor (TGF)-beta, monocyte chemotactic protein (MCP)-1, L32, and GAPDH (9, 13, 17). Total RNA was extracted from the LV by an acid guanidium-thiocyanate-phenolchloroform method. The value of each hybridized probe was normalized to that of GAPDH, included in each template set as an internal control.

Enzyme-linked immunosorbent assay. Murine myocardial TNFR1 and TNFR2 protein levels were assessed using enzyme-linked immunosorbent assay (ELISA) (Quantikine; R&D Systems) according to the manufacturer's instructions by using 100 µg protein/sample (10). Results obtained from spectrophotometry were compared against serial dilutions of known concentrations of the respective standards. Results were expressed as picograms of target protein per gram of total protein.

Immunohistochemistry. Sections fixed in formaldehyde were incubated with an Armenian hamster anti-mouse TNFR1 monoclonal antibody (sc-12746; Santa Cruz Biotechnology) or an Armenian hamster anti-mouse TNFR2 monoclonal antibody (sc-12751; Santa Cruz Biotechnology) overnight at 4°C, washed three times, and incubated with affinity-purified biotinylated goat anti-Armenian hamster IgG (sc-2445; Santa Cruz Biotechnology) for 1 h at room temperature. They were washed again and overlaid with streptavidin-biotin-peroxidase complex (Nichirei, Tokyo, Japan) for 1 h at room temperature. After a final wash, the reactivity was visualized with diaminobenzidene (DAB; Nichirei). Counterstaining was then performed with Mayer's hematoxylin (14).

Statistical analysis. The results are mean (SD). Statistical comparisons were performed using ANOVA with Students-Newman-Keuls post hoc test or unmatched Student's t-test where appropriate. When the Levene test for homogeneity of variance revealed significant differences between groups, nonparametric tests (Kruskal-Wallis and Mann-Whitney U test) were performed on the variables. Survival analysis was performed using the Kaplan-Meier method, and the between-group difference in survival was tested using the log-rank test. Differences were considered significant at a P value <0.05.


   RESULTS
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
DISCUSSION
 GRANTS
 REFERENCES
 
Decreased mortality due to congestive heart failure with R1KO. Survival analysis was performed in six groups of mice: sham/WT, sham/R1KO, sham/R2KO, MI/WT, MI/R1KO, and MI/R2KO. Mice that died within 12 h after operation were excluded, because early operative mortality was not different among MI/WT (18.9%), MI/R1KO (17.4%), and MI/R2KO mice (19.7%). No mice died after sham operation. In contrast, as shown in Fig. 1A, 25 of 60 MI/WT, 14 of 57 MI/R1KO, and 28 of 61 MI/R2KO mice died by the end of 4 wk after coronary ligation. Homozygous ablation of TNFR1 significantly (P < 0.05) decreased the post-MI mortality compared with WT. The cause of death was classified as either congestive heart failure or ventricular rupture, because all mice died from either congestion (pleural effusion and increased lung weight) or blood clot in the pericardial sac. Although the mortality due to ventricular rupture was not different among MI/WT, MI/R1KO, and MI/R2KO mice (Fig. 1B), mortality presumably due to congestive heart failure was significantly lower in MI/R1KO compared with MI/WT mice (Fig. 1C). Percent infarct area did not differ among MI/WT, MI/R1KO, and MI/R2KO mice, as described below.


Figure 1
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  		Fig. 1. A: Kaplan-Meier survival curves of coro nary ligated (MI) mice: wild type (WT), TNF receptor 1 knockout (R1KO), and TNF receptor 2 knockout (R2KO). B and C: mortality curves of coronary ligated mice for ventricular rupture (B) and congestive heart failure (C). {dagger}P < 0.05 vs. WT mice.

 
No differences in hemodynamic changes immediately after MI among WT, R1KO, and R2KO mice. Echocardiography showed that the coronary artery ligation did not affect LV end-diastolic dimension but significantly decreased fractional shortening in MI/WT mice. Similar changes in fractional shortening were also observed in R1KO and R2KO mice (Table 1). Pressure measurement with a tail-cuff system showed no significant differences in heart rate among the six groups, but blood pressure was significantly lower in MI/WT compared with sham/WT mice. Similar changes in blood pressure were also observed in R1KO and R2KO mice (Table 1).


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  		Table 1. Characteristics of animal models immediately after coronary artery ligation (day 0)

 
No differences in ventricular dysfunction among WT, R1KO, and R2KO on day 3. Echocardiography showed that cardiac dimensions of surviving mice on day 3 were significantly higher and fractional shortening was significantly lower in MI/WT compared with sham/WT mice. Similar changes in cardiac dimensions and fractional shortening were also observed in R1KO or R2KO mice (Table 2). The ratio of Lung weight to body weight also increased significantly in MI/WT mice, and significant increases were also observed in R1KO and R2KO mice (Table 2). Pressure measurement with a tail-cuff system showed no significant differences in heart rate and systemic blood pressure among the six groups (Table 2). These results suggest that inhibition of TNFR1- or TNFR2-mediated pathways does not affect ventricular dysfunction and pulmonary congestion in the acute phase of MI.


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  		Table 2. Characteristics of animal models in the acute phase of coronary artery ligation (day 3)

 
Exacerbation of ventricular dysfunction and remodeling with R2KO on day 28. Echocardiography showed that cardiac dimensions of surviving mice on day 28 were significantly higher in MI/WT than in sham/WT mice. MI/R1KO mice showed significantly less cavity dilatation with improvement of contractile dysfunction compared with MI/WT mice. In contrast, MI/R2KO mice showed significantly more cavity dilatation with exacerbation of contractile dysfunction (Table 3). Pressure measurement with a Millar catheter showed no significant differences in heart rate and aortic blood pressure among the six groups. However, LV end-diastolic pressure, which increased significantly in MI/WT mice, was further augmented significantly in MI/R2KO mice. Both maximum and minimum first derivatives of LV pressure, which decreased significantly in MI, were further lowered significantly in MI/R2KO mice, whereas they increased significantly in MI/R1KO mice (Table 3). Along with increased LV end-diastolic pressure, lung weight/body weight ratio also increased significantly in MI/WT mice with further increment in MI/R2KO mice (Table 3). These results suggest that inhibition of TNFR1-mediated pathways attenuates ventricular dysfunction and improves post-MI survival. In contrast, inhibition of TNFR2-mediated pathways exacerbates ventricular dysfunction and pulmonary congestion.


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  		Table 3. Characteristics of animal models in the subacute phase of coronary artery ligation (day 28)

 
Although body weight was similar among the six groups, LV weight/body weight ratio increased significantly in MI/WT mice and was further exacerbated in MI/R2KO mice (Table 3). Cross-sectional area of cardiomyocytes was evaluated to confirm increased ventricular hypertrophy in MI/R2KO mice on day 28 (Fig. 2A). As summarized in Fig. 2B, cross-sectional area, which was increased in MI/WT noninfarct myocardium, was further increased significantly in MI/R2KO mice but did not differ significantly in MI/R1KO compared with MI/WT mice. Collagen was visualized in LV cross sections with Picrosirius red staining (Fig. 2C). Collagen volume fraction, which was increased in MI/WT noninfarct myocardium, was further increased significantly in MI/R2KO mice (Fig. 2D).


Figure 2
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  		Fig. 2. A and B: effects of myocardial infarction (MI) on ventricular hypertrophy: representative micrographs of hematoxylin-eosin staining of myocardium (A) and cross-sectional area (CSA) of cardiomyocytes (B). C and D: collagen volume analysis of the noninfarct myocardium on day 28 after MI: representative micrographs of Picrosirius red staining (C) and summarized data for collagen volume fraction (D). Values are means (SD). Sham denotes sham-operated mice. *P < 0.05 vs. sham/WT mice. {dagger}P < 0.05 vs. MI/WT mice.

 
Increased myocardial expression of TNFR1 by R2KO. Multiprobe RPA was used to evaluate the expression of TNFR1 and TNFR2 in noninfarct myocardium 28 days after MI or sham operation (Fig. 3A). The transcript level of TNFR1, which was nullified in R1KO, was not affected by MI but was significantly upregulated in MI/R2KO mice (Fig. 3B). In contrast, the transcript level of TNFR2, which was nullified by R2KO, was significantly upregulated by MI and was not further upregulated in MI/R1KO mice.


Figure 3
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  		Fig. 3. A and B: multiprobe RNase protection assays for TNF receptors in noninfarct myocardium on day 28 after MI: representative gels (A) and summarized data for densitometric analysis (B). Each value is normalized to that of GAPDH, included in each template set as an internal control. C: enzyme-linked immunosorbent assay for TNF receptors. Values are means (SD). *P < 0.05 vs. sham/WT mice. {dagger}P < 0.05 vs. MI/WT mice.

 
ELISA was used to evaluate protein levels of TNFR1 and TNFR2 in noninfarct myocardium on day 28 (Fig. 3C). Ablation of the appropriate TNF receptor was evidenced by the fact that TNFR1 and TNFR2 protein levels were not appreciable in the MI/R1KO and MI/R2KO mice, respectively (approximately equal to or lower than the limit of detection, <1.56 pg/mg protein). Consistent with the transcript levels, the cardiac TNFR1 protein level, which was not affected by MI in WT mice, was elevated approximately twofold in MI/R2KO compared with MI/WT mice. In contrast, the cardiac TNFR2 protein level was elevated approximately threefold by MI and was not increased further by R1KO.

To confirm the increased expression of TNFR1 protein in MI/R2KO mice, we performed immunohistochemical staining of TNFR1 (Fig. 4A). Consistent with the results of ELISA, TNFR1 staining did not increase in MI/WT mice but increased in MI/R2KO mice. Next, immunohistochemical staining of TNFR2 was performed to confirm the increased expression of TNFR2 protein in MI/WT and MI/R1KO mice (Fig. 4B). Consistent with the results of ELISA, TNFR2 staining was increased in response to MI in WT and R1KO mice. The staining was localized to the membrane of cardiomyocytes.


Figure 4
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  		Fig. 4. Immunohistochemistry for TNF receptors in noninfarct myocardium on day 28 after MI: representative micrographs of TNFR1 staining (A) and representative micrographs of TNFR2 staining (B). Higher power, x400 magnification.

 
Augmented myocardial expression of proinflammatory cytokines with R2KO. Multiprobe RPA was also used to evaluate the expression of proinflammatory cytokines and chemokines in noninfarct myocardium 28 days after MI or sham operation (Fig. 5A). The transcript level of TNF-{alpha} was significantly upregulated in noninfarct myocardium in WT and was not modified by the ablation of TNFR1 or TNFR2 (Fig. 5B). Transcript levels of IL-6, IL-1beta, TGF-beta, and MCP-1, which were significantly upregulated in MI/WT noninfarct myocardium, were significantly downregulated in MI/R1KO compared with MI/WT mice. In contrast, transcript levels of IL-6 and IL-1beta were significantly further upregulated in MI/R2KO noninfarct myocardium compared with MI/WT mice (Fig. 5C).


Figure 5
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  		Fig. 5. Multiprobe RNase protection assays for proinflammatory cytokines and chemokines in noninfarct myocardium on day 28 after MI: representative gels (A) and summarized data for densitometric analysis (B and C). TGF-beta, transforming growth factor-beta; MCP-1, monocyte chemotactic protein-1. Each value is normalized to that of GAPDH, included in each template set as an internal control. Values are means (SD). *P < 0.05 vs. sham/WT mice. {dagger}P < 0.05 vs. MI/WT mice.

 

   DISCUSSION
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
GRANTS
 REFERENCES
 
Proinflammatory cytokines including TNF-{alpha} have been implicated in the pathogenesis of cardiovascular diseases (5, 20). However, the roles of TNF-{alpha} in MI remain controversial. Blockade of TNF-{alpha} has been reported to be both beneficial (1, 15, 24, 26, 27) and deleterious (2, 18, 22). In the present study, we evaluated the pathophysiological roles of two distinct cell surface receptors (TNFR1 and TNFR2) in the process of infarct healing and cardiac remodeling after MI. Inhibition of TNFR1-mediated pathways attenuated ventricular dysfunction and improved post-MI survival, concomitant with downregulation of other proinflammatory cytokines in noninfarct myocardium. In contrast, inhibition of TNFR2-mediated pathways exacerbated ventricular dysfunction and remodeling, accompanied by upregulation of TNFR1 and other proinflammatory cytokines in noninfarct myocardium. To the best of our knowledge, this study is the first to document that the ablation of TNFR2 exacerbates ventricular dysfunction and remodeling after MI.

Most biological activities of TNF-{alpha} have been considered to be mediated by TNFR1 pathways (33). Three functional domains of TNFR1, the COOH-terminal death domain (28) and the adjacent N-SMase (neutral sphingomyelinase) and A-SMase (acidic sphingomyelinase) activating domains (NSD and ASD, respectively) (25, 34), transfer signals from extracellular TNF-{alpha} to intracellular adaptor proteins. The ASD is capable of inducing activation of NF-{kappa}B to protect cells against apoptosis (31, 32) and promote inflammation. Ramani et al. (24) have reported that knockout of TNFR1 improves the survival of MI mice. Activation of TNFR1 has been shown to induce various proinflammatory cytokines and chemokines, most of which are considered to be cardiotoxic (5, 20). In the present study, we demonstrated that knockout of TNFR1 suppresses the induction of proinflammatory cytokines and chemokines after MI. These results suggest that TNFR1-mediated pathways are cardiotoxic by inducing various proinflammatory cytokines and chemokines.

Little is known about the roles of TNFR2-mediated pathways. TNFR2 lacks an intracellular death domain (33), suggesting that TNFR2 uses distinct signaling pathways to induce apoptosis (19). Furthermore, whether TNFR2 alone can mediate the activation of NF-{kappa}B is controversial (3, 11, 12). Higuchi et al. (10) demonstrated that knockout of TNFR2 increased the mortality by exacerbating the development of heart failure in transgenic mice with cardiac-specific overexpression of TNF-{alpha}. In the present study, we have demonstrated that knockout of TNFR2 exacerbates ventricular dysfunction and remodeling after MI together with upregulation of IL-6 and IL-1beta. These results suggest that TNF-{alpha} may protect the myocardium via TNFR2-mediated pathways. Because knockout of TNFR2 upregulates TNFR1 after MI, the beneficial roles of TNFR2 may be mediated partially by suppression of TNFR1-mediated pathways. The interaction of TNFR1 and TNFR2 pathways may play important roles in MI. In addition, Goukassian et al. (7) recently reported that in a hindlimb ischemia model, endothelial cell apoptosis was increased, and capillary density was decreased in R2KO ischemic tissue. We indeed have evaluated apoptosis in the present study. The number of TdT-mediated dUTP nick end labeling-positive cells increased only slightly in the noninfarct myocardium on day 28 after MI, regardless of R1KO or R2KO (data not shown). DNA laddering assay also indicated slightly increased apoptosis in noninfarct myocardium and also was not affected by RIKO or R2KO (data not shown). These results indicate that apoptosis in the noninfarct myocardium is not affected by the presence or absence of TNFR1 or TNFR2. The effects of TNFR1 and TNFR2 pathways on nonischemic myocardium after MI may be different from those on ischemic limb tissue.

There are several important aspects to consider in interpreting the results of the present study. First, we used knockout mice to completely block the activation of TNFR1 or TNFR2 pathways. Although growth, appearance, and cardiac function under unstressed conditions seem to be unaffected by R1KO or R2KO, the absence of TNFR1 or TNFR2 during embryogenesis and development may alter other signaling pathways to secure physiological growth of these mice. Therefore, caution has to be exercised in interpreting the present results in association with those obtained from clinical trials. Further studies with selective pharmacological ablation of TNFR1 or TNFR2 pathways are required to validate the results of the present study in clinical settings. Second, it is possible that various proinflammatory cytokines play dual roles in post-MI cardiac remodeling and function, as is the case with TNF-{alpha}. Therefore, we cannot simply conclude that overexpression of these cytokines in post-MI myocardium is detrimental. Alternatively, overexpression of IL-6 and IL-1beta in MI/R2KO mice may represent a compensatory mechanism to salvage the dysfunctional myocardium.

In conclusion, in a murine model of MI, inhibition of TNFR1-mediated pathways attenuates ventricular dysfunction and improves survival with downregulation of other proinflammatory cytokines. In contrast, inhibition of TNFR2-mediated pathways exacerbate ventricular dysfunction and remodeling with upregulation of TNFR1 and other proinflammatory cytokines in noninfarct myocardium. The findings of the present study may partially explain the unexpected results of anti-TNF-{alpha} clinical trials for heart failure. Because TNF-{alpha} seems to play both toxic and protective roles in cardiovascular diseases, selective blockade of cardiotoxic TNFR1 may be a candidate therapeutic intervention in clinical practice.


   GRANTS
TOP
 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
REFERENCES
 
A part of this study was conducted at Kyushu University Station for Collaborative Research. This study was supported by a grant from Kimura Memorial Heart Foundation, a Grant for Research on Cardiovascular Disease from Japan Heart Foundation/Pfizer Pharmaceuticals, Inc., a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (C15590755), a Health and Labour Sciences Research Grant for Research on Advanced Medical Technology from the Ministry of Health, Labour and Welfare of Japan (H14-Nano-002), a Health and Labour Sciences Research Grant for Research on Medical Devices for Analyzing, Supporting and Substituting the Function of Human Body from the Ministry of Health, Labour and Welfare of Japan (H15-Physi-001), and a Health and Labour Sciences Research Grant for Research on Measures for Intractable Disease from the Ministry of Health, Labour and Welfare of Japan (H17-Nanchi-22).


   FOOTNOTES
 

Address for reprint requests and other correspondence: T. Kubota, Dept. of Cardiovascular Medicine, Kyushu Univ. Graduate School of Medical Sciences, 3-1-Maidashi, Higashi-ku, Fukuoka 812-8582, Japan (e-mail: kubotat{at}cardiol.med.kyushu-u.ac.jp)

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.


   REFERENCES
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 ABSTRACT
 MATERIALS AND METHODS
 RESULTS
 DISCUSSION
 GRANTS
 REFERENCES
 

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