Osteopontin (OPN) is upregulated in left ventricular hypertrophy and is stimulated by angiotensin II (AngII). Our objective was to determine whether mice deficient in OPN would be protected from ...AngII-induced cardiac fibrosis.
Interstitial fibrosis can lead to myocardial dysfunction and ultimately heart failure. Osteopontin activates integrins that regulate cell adhesion, migration, and growth, thus implicating OPN in the process of cardiac fibrosis.
Osteopontin null (OPN−/−) mice (n = 18) and wild-type controls (n = 20) were infused with AngII (2.5 or 3.0 μg/kg/min) for four days or three weeks via osmotic mini-pumps. Hearts were assessed morphometrically and histologically, including quantitative assessment of fibrosis via optical microscopic imaging analysis. Cardiac fibroblasts derived from these mice were evaluated for adhesion and proliferation. Cardiac transcript expression for cytokines, extracellular matrix (ECM), integrin, and atrial natriuretic peptide were assessed.
Osteopontin−/−mice exhibited less cardiac fibrosis (0.7%) than wild-type mice (8.0%) (p < 0.01) and lowered heart/body weight ratios (0.10% vs. 0.23%) (p < 0.01) after three weeks of AngII infusion. Expression of transforming growth factor-beta, fibronectin, and collagen was not different between OPN−/−and wild-type mice, despite the decrease in ECM accumulation in the OPN−/−mice. Adhesion to ECM substrates decreased by 30% to 50% in cardiac fibroblasts of OPN−/−mice but was restored in OPN−/−cells by the addition of recombinant osteopontin.
Osteopontin mediates cardiac fibrosis, probably through the modulation of cellular adhesion and proliferation. Because OPN is increased in cardiac hypertrophy and its lack attenuates fibrosis, understanding of OPN function is essential to extend our knowledge about molecular determinants of cardiac hypertrophy and failure.
Abstract Introduction Several anticoagulants have been associated with a ‘rebound effect’ that potentially increases the risk of thrombosis and cardiovascular events following discontinuation. Four ...Phase 3 trials of dabigatran etexilate in major orthopedic surgery incorporated measures to assess the risk of acute coronary syndrome (ACS) events during and after treatment. Materials and methods Patients in RE-MOBILIZE®, RE-MODEL™, RE-NOVATE®, and RENOVATE® II were randomized to dabigatran etexilate (150 mg or 220 mg once daily) or enoxaparin for 6–35 days, and followed for up to 90 days. ACS data were tabulated from investigator-reported serious adverse events using ACS-specific Medical Dictionary for Regulatory Authorities (MedDRA) lower-level terms. To ensure that all ACS events were identified in the initial three studies, RE-MOBILIZE®, RE-MODEL™, and RE-NOVATE®, a broader list of MedDRA terms was prespecified that would trigger treatment-blinded adjudication. Results When pooling the four trials, patients receiving dabigatran etexilate 220 mg had the fewest treatment-emergent, investigator-reported ACS events (6 0.16% vs 14 0.51% for dabigatran 150 mg and 13 0.35% for enoxaparin). Corresponding post-treatment rates were 2 (0.06%), 1 (0.04%), and 4 (0.11%). Similarly, treatment-emergent centrally adjudicated definite or likely ACS events in the first three trials were fewer in patients on dabigatran 220 mg (16 0.60%) than dabigatran 150 mg (26 0.95%) and enoxaparin (20 0.74%). The corresponding numbers post treatment were 2, 2, and 7. None of these between-group differences were statistically significant. Conclusion No increased ACS signal was detected with dabigatran etexilate compared with enoxaparin during or after treatment.
Abstract 205
Dabigatran has been compared with warfarin for treatment of acute venous thromboembolism in one previous trial (RE-COVER). Based on the low rate of the primary outcome as the RE-COVER ...study was running, we undertook this replica study to confirm the results of RE-COVER, and to allow for more rigorous sub-group analyses.
In a randomized, double-blind, double-dummy trial of 2568 patients with acute VTE, treated with low molecular weight or unfractionated heparin for 5 to 11 days, we compared dabigatran, 150 mg twice daily, with warfarin, dose-adjusted to an International Normalized Ratio of 2.0 and 3.0, each given for 6 months. Primary outcome was recurrent symptomatic, objectively confirmed venous thromboembolism and deaths related to venous thromboembolism during 6 months. Safety endpoints included bleeding events, acute coronary syndrome, elevated liver function tests, and adverse events.
Of 1279 patients randomized to dabigatran, 30 (2.4%) had recurrent VTE compared with 28 (2.2%) of 1289 patients randomized to warfarin; risk difference 0.2% (95% confidence interval CI, −1.0 to 1.5); p<0.0001 for the pre-specified non-inferiority margin. The hazard ratio for dabigatran was 1.08 (95% CI, 0.64 to 1.80). Major bleeding occurred in 15 patients treated with dabigatran and 22 patients treated with warfarin (hazard ratio 0.69; 95% CI, 0.36 to 1.32) and any bleeding occurred in 200 versus 285 patients, respectively (hazard ratio 0.67, 95% CI, 0.56 to 0.81). The frequency of reported ACS events was less than 1% in the trial, with more cases in the dabigatran treatment group than those treated with warfarin. There were 25 deaths during each treatment, and serious adverse events were similar in the two groups. Analysis of outcomes based on demographic characteristics showed consistency of effects for both safety and efficacy. This included the analysis based on Asian race, which had been limited in RE-COVER. There were 537 Asian patients in RE-COVER II compared to only 65 in RE-COVER. The event rates of recurrent VTE and of any bleeding were similar in Asians and non-Asians.
The study confirms that the efficacy of dabigatran is non-inferior to warfarin in the treatment of acute VTE and with a lower risk for bleeding. The safety of dabigatran is similar in the Asian population compared with non-Asians.
Off Label Use: dabigatran for treatment of venous thromboembolism. Christiansen:Boehringer Ingelheim: Employment. Schnee:Boehringer Ingelheim: Employment.
The cDNAs encoding two human homologs of the Xenopus oocyte lectin, XL35, were isolated from a small intestine cDNA library and termed HL-1 and HL-2. The deduced amino acid sequence of each homolog ...is about 60% identical and 80% similar to that of XL35, and none of these sequences contains the C-type lectin motif, although it is known that XL35 requires calcium for ligand binding. By Northern analysis, HL-1 transcripts are present at relatively high levels in heart, small intestine, colon, thymus, ovary, and testis. HL-2 transcripts, by contrast, are expressed only in small intestine. Immunocytochemistry using a polyclonal antibody produced against XL35 shows HL-1 protein to be localized exclusively in endothelial cells in colon, thymus, liver, and other tissues. Primary cultures of human aortic endothelial cells are positive for HL-1 expression by immunoblotting and by PCR analysis, but several other human cell types are not. HL-1 and -2 are both encoded at chromosome 1q23, the same locus that encodes the selectins. XL35, HL-1 and -2, and another mouse homolog are members of a new family of proteins whose members most likely perform diverse functions.
Abstract 1▪▪This icon denotes an abstract that is clinically relevant.
Background. The direct oral thrombin inhibitor, dabigatran etexilate, has a predictable anticoagulant effect and may be an ...alternative to warfarin in patients with acute venous thromboembolism (VTE). Methods. In a randomized, double-blind, trial of 2539 patients with acute VTE, treated with low molecular weight or unfractionated heparin for 5 to 11 days, we compared oral dabigatran etexilate, 150 mg twice daily in a fixed-dose, with warfarin dose-adjusted to an International Normalized Ratio of 2.0 and 3.0, each given for 6 months. The primary outcome was symptomatic, objectively confirmed recurrent VTE or VTE-related death up to 6 months of treatment. Safety endpoints included bleeding events, acute coronary syndrome, liver function tests, vital signs and adverse events. Results. Of 1274 patients randomized to dabigatran etexilate, at 6 months 30 (2.4%) had recurrent VTE compared with 27 (2.2%) of 1265 patients randomized to warfarin; risk difference 0.4% 95 percent confidence interval, −0.8 to 1.5; p<0.0001 for prespecified non-inferiority margin. During the planned study participation, through the end of the follow-up period, there were 34 vs. 32 patients who had recurrent VTE in the dabigatran etexilate vs. warfarin treated groups, respectively (hazard ratio 1.05 95% confidence interval, 0.065 to 1.70). Major bleeding occurred in 20 patients treated with dabigatran etexilate and 24 patients treated with warfarin (hazard ratio 0.82; 95 percent confidence interval, 0.45 to 1.48) and any bleeding occurred in 207 versus 280 patients, respectively (hazard ratio 0.71, 95 percent confidence interval, 0.59 to 0.85). Death, acute coronary syndromes, and liver function test abnormalities were infrequent and similar in the two groups. Conclusion: Fixed-dose dabigatran etexilate is as effective and safe as warfarin in the treatment of acute VTE.
Schulman:GSK: Honorarium for Chairman of the IDMC; Bayer HealthCare: Honorarium for Chairman of the DSMB; Boehringer-Ingelheim: Honorarium for Chairman of the Steering Committee; Sanofi-Aventis: Honorarium for Chairman of the DSMB, Research Funding. Off Label Use: Dabigatran etexilate is an oral thrombin inhibitor under investigation for anticoagulant prophylaxis or treatment in venous and arterial thrombomebolism. Kakkar:Bayer HealthCare: Consultancy, Honoraria, Research Funding, Scientific Advisory Board; Sanofi-Aventis: Consultancy, Honoraria, Research Funding, Scientific Advisory Board; Boehringer Ingelheim: Consultancy, Honoraria, Research Funding, Scientific Advisory Board; Pfizer: Consultancy, Honoraria, Research Funding, Scientific Advisory Board; Bristol–Myers Squibb: Consultancy, Honoraria, Research Funding, Scientific Advisory Board; Eisai: Consultancy, Honoraria, Research Funding, Scientific Advisory Board; Aryx therapeutics: Consultancy; GSK: Honoraria. Schellong:Bayer HealthCare: Consultancy, Honoraria, Scientific Advisory Board; Sanofi-Aventis: Consultancy, Honoraria, Scientific Advisory Board; Boehringer Ingelheim: Consultancy, Honoraria, Scientific Advisory Board; Pfizer: Scientific Advisory Board; Bristol–Myers Squibb: Consultancy, Honoraria, Scientific Advisory Board; Esai: Consultancy, Honoraria, Scientific Advisory Board; Aryx therapeutics: Consultancy; GSK: Honoraria. Baanstra:Boehringer-Ingelheim: Employment. Schnee:Boehringer-Ingelheim: Employment.
The oral direct thrombin inhibitor, Dabigatran etexilate (Pradaxa®), was recently approved in Europe for the prevention of venous thromboembolism (VTE) in patients undergoing elective total knee ...replacement or total hip replacement surgery. Two pivotal clinical trials studied doses of 220 mg once daily and 150 mg once daily compared with 40 mg enoxaparin. A post hoc pooled analysis was performed in elderly patients (>75 years) since the elderly, naturally lose renal function with aging. The efficacy and safety of once daily 220 mg and 150 mg dabigatran etexilate were compared with 40 mg subcutaneous enoxaparin using pooled data from the RE-MODEL (Eriksson BI et al. J Thromb Haemost 2007; 5: 2178–2185) and RE-NOVATE (Eriksson BI et al. Lancet 2007; 370: 949–956) pivotal trials. The primary efficacy endpoint was total VTE and all cause mortality and the primary secondary efficacy endpoint was major VTE and VTE related mortality. The primary safety endpoint was bleeding events, which were blindly adjudicated and categorized as major bleeding events (MBE), including surgical site bleeds. Of the patients treated with 220 mg dabigatran etexilate (1825), 150 mg dabigatran etexilate (1866) and enoxaparin (1848), 883 patients (16%) were above the age of 75, 73% of the elderly were evaluable for the primary efficacy endpoint, 75% were evaluable for the secondary efficacy endpoint, and all elderly patients were evaluable for safety including bleeding. The incidence of total VTE and all cause mortality was 20.8%, 22.6%, and 27.2% respectively in the three groups. A similar trend was observed for the secondary endpoint major VTE and VTE related mortality, with a descriptive statistical significant lower event rate in the 220 mg group (see table). MBEs occurred in 11 of the 295 elderly receiving 220 mg dabigatran etexilate (3.7%), 4 of the 282 elderly receiving 150 mg dabigatran etexilate (1.4%) and in 9 of the 306 elderly taking enoxaparin (2.9%). Notably, 6 of the 11 MBE in the dabigatran 220 mg group and 2 of the 4 MBE in the 150 mg group started before first oral treatment. In conclusion, in elderly patients (>75 years) undergoing hip or knee replacement surgery, oral 150 mg dabigatran etexilate exhibited favourable bleeding profile with no difference in efficacy compared to 40 mg enoxaparin. Because safety is of paramount importance in the elderly who are at risk of any complications, the 150 mg once daily of dabigatran etexilate dose is currently recommended for this group.
Table 1: Efficacy and bleeding endpoints in patients older than 75 years (p-value from Fisher's exact test compared to Enoxaparin)
EventDabigatran etexilate 220 mg qdDabigatran etexilate 150 mg qdEnoxaparin 40 mg qdTotal VTE and all cause mortality20.8% (44/212) (CI 15.5%–26.8%) p=0.1422.6% (49/217) (CI 17.2%–28.7%) p=0.3227.2% (58/213) (CI 21.4%–33.7%)Major VTE and VTE related mortality1.9% (4/216) (CI 0.5%–4.7%) p=0.0454.5% (10/221) (CI 2.2%–8.2%) p=0.536.0% (13/218) (CI 3.2%–10.0%)MBE3.7% (11/295) (CI 1.9%–6.6%) p=0.651.4% (4/282) (CI 0.4%–3.6%) p=0.272.9%% (9/306) (CI 1.4%–5.5%)
Dabigatran etexilate (Pradaxa®), an oral direct thrombin inhibitor, was recently approved in Europe for the prevention of venous thromboembolism (VTE) in patients undergoing elective total knee ...replacement or total hip replacement surgery. In phase III clinical trials two doses were studied: 220 mg once daily and 150 mg once daily. A post hoc pooled analysis was performed in patients with moderate renal impairment (GFR ≥30 and < 50 mL/min). The efficacy and safety of 220 mg and 150 mg dabigatran etexilate were compared with 40 mg subcutaneous enoxaparin. The analysis included data from the RE-MODEL (Eriksson BI et al. J Thromb Haemost 2007; 5: 2178–2185) and the RE-NOVATE (Eriksson BI et al. Lancet 2007; 370: 949–956) pivotal trials. The primary efficacy endpoint in both studies and this analysis was total VTE and all cause mortality, similarly, the key pre-specified secondary efficacy endpoint was major VTE and VTE-related mortality. Bleeding events (primary safety endpoint) were blindly adjudicated and categorized as major bleeding events (MBE) including surgical site bleeds. Of the patients treated with 220 mg dabigatran etexilate (1825), 150 mg dabigatran etexilate (1866) and 40 mg enoxaparin (1848), 337 patients had moderate renal impairment. 68% of these patients were evaluable for the primary efficacy endpoint, 242 were evaluable for the secondary efficacy endpoint, and all patients were available for safety and bleeding. The incidence of total VTE and all cause mortality was 17.7%, 23.5% and 27.8% in the 220 mg, 150 mg dabigatran etexilate and enoxaparin groups respectively. When the secondary endpoint was analyzed a similar trend, with a descriptive statistical significance for a lower event rate in the 220 mg group, was seen (see table). MBEs occurred in 6 of 113 patients in the 220 mg dabigatran treated group (5.3%), in none of the patients in the 150 mg dabigatran etexilate treated group (0.0%), and in 6 of 128 patients receiving 40 mg enoxaparin (4.7%). Notably, 3 of the 6 major bleeding events in the 220mg group started before any oral dabigatran etexilate treatment. In conclusion, in patients with moderate renal impairment undergoing hip or knee replacement surgery, oral 150 mg dabigatran etexilate showed similar efficacy compared with subcutaneous 40 mg enoxaparin, with apparently lower rates of major bleeding. Because of the potential negative impact of major bleeding especially in this population the 150 mg once daily dabigatran etexilate dose is currently recommended for this group.
Table 1: Efficacy and bleeding endpoints in patients with moderate renal impairment (p-value from Fisher's exact test compared to Enoxaparin)
EventDabigatran etexilate 220 mg qdDabigatran etexilate 150 mg qdEnoxaparin 40 mg qdTotal VTE and all cause mortality17.7% (14/79) (CI 10.0%–27.9%) p=0.1423.5% (16/68) (CI 14.1%–35.4%) p=0.5927.8% (25/90) (CI 18.9%–38.2%)Major VTE and VTE related mortality1.2% (1/83) (CI 0.0%–6.5%) p=0.044.3% (3/70) (CI 0.9%–12.0%) p=0.359.0% (8/89) (CI 4.0%–16.9%)MBE5.3% (6/113) (CI 2.0%–11.2%) p=0.820.0% (0/96) (CI 0.0–3.8%) p=0.044.7% (6/128) (CI 1.7%–9.9%)
Angiotensin II (Ang II) plays an important role in cardiac remodeling through stimulation of proliferation and extracellular matrix (ECM) production in cardiac fibroblasts. Integrins are a family of ...transmembrane receptors that mediate the attachment of cells to ECM. We hypothesized that Ang II regulation of integrins further contributes to its role in cardiac remodeling. We cultured adult rat cardiac fibroblasts with and without Ang II (100 nmol/L) to determine the effects on mRNA and protein levels of integrins, as well as alpha-actinin and other cytoskeletal proteins that link to integrins at the site of focal adhesions. Ang II was also added in the presence of irbesartan (10 micromol/L), a specific Ang II type 1 (AT(1)) receptor antagonist, or PD 123319 (10 micromol/L), a specific Ang II type 2 receptor antagonist. To investigate the function of these integrins, we determined the effects of blocking antibodies on Ang II-induced adhesion to ECM. We also treated spontaneously hypertensive rats (SHR) with an AT(1) receptor blocker, losartan, or with hydralazine to investigate integrin and alpha-actinin expression in treated and untreated SHR. Ang II enhanced alpha(v), beta(1), beta(3), and beta(5) integrins; osteopontin; and alpha-actinin mRNA and protein levels in cardiac fibroblasts. All of these effects were inhibited by irbesartan but not by PD 123319. Pretreatment of cardiac fibroblasts with Ang II enhanced cell attachment to ECM proteins and induced focal adhesion kinase phosphorylation. Blocking antibodies to beta(3) and alpha(v)beta(5) attenuated Ang II-induced adhesion. In SHR, ventricular alpha(v) and beta(5) integrin expression and alpha-actinin were increased compared with those in Wistar-Kyoto rats. Although both losartan and hydralazine lowered mean arterial pressure and decreased peripheral vascular resistance, only losartan attenuated the increased integrin, alpha-actinin, fibronectin laminin, and osteopontin expression and the increased left ventricular mass (as determined with echocardiography). Hydralzine had none of these effects. Although both agents attenuated beta-myosin heavy chain expression, a marker of hypertrophy, losartan had a greater effect. These results suggest that integrins and alpha-actinin are upregulated by Ang II and in left ventricular hypertrophy and that the block of expression of these proteins through inhibition of the AT(1) receptor is associated with attenuation of the hypertrophic response. Ang II induces integrin and alpha-actinin expression in cardiac fibroblasts that is associated with adhesion and left ventricular hypertrophy and blocked through inhibition of the AT(1) receptor.
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