Severe pulmonary hypertension in aging female apolipoprotein E-deficient mice is rescued by estrogen replacement therapy

BackgroundApolipoprotein E (ApoE) is a multifunctional protein, and its deficiency leads to the development of atherosclerosis in mice. Patients with pulmonary hypertension (PH) have reduced expression of ApoE in lung tissue. ApoE is known to inhibit endothelial and smooth muscle cell proliferation and has anti-inflammatory and anti-platelet aggregation properties. Young ApoE-deficient mice have been shown to develop PH on high fat diet. The combined role of female sex and aging in the development of PH has not been investigated before. Here, we investigated the development of PH in young and middle-aged (MA) female ApoE-deficient mice and explored the role of exogenous estrogen (E2) replacement therapy for the aging females.MethodsWild type (WT) and ApoE-deficient female mice (Young and MA) were injected with a single intraperitoneal dose of monocrotaline (MCT, 60 mg/kg). Some ApoE-deficient MA female mice that received MCT were also treated with subcutaneous E2 pellets (0.03 mg/kg/day) from day 21 to 30 after MCT injection. Direct cardiac catheterization was performed terminally to record right ventricular systolic pressure (RVSP). Right ventricular (RV), left ventricular (LV), and interventricular septum (IVS) were dissected and weighed. Lung sections were examined using trichrome and immunofluorescence staining. Western blot analyses of lung and RV lysates were performed.ResultsIn WT female mice, the severity of PH was similar between young and MA mice as RVSP was not significantly different (RVSP = 38.2 ± 1.2 in young vs. 40.5 ± 8.3 mmHg in MA, p < 0.05). In ApoE-deficient mice, MA females developed significantly severe PH (RVSP = 63 ± 10 mmHg) compared to young females (RVSP; 36 ± 3 mmHg, p < 0.05 vs. MA female). ApoE-deficient MA females also developed more severe RV hypertrophy compared to young females (RV hypertrophy index (RV/[LV + IVS]) = 0.53 ± 0.06 vs. 0.33 ± 0.01, p < 0.05). ApoE-deficient MA female mice manifested increased peripheral pulmonary artery muscularization and pulmonary fibrosis. E2 treatment of MA female ApoE-deficient mice resulted in a significant decrease in RVSP, reversal of pulmonary vascular remodeling, and RV hypertrophy. In MA female ApoE-deficient mice with PH, only the expression of ERβ in the lungs, but not in RV, was significantly downregulated, and it was restored by E2 treatment. The expression of ERα was not affected in either lungs or RV by PH. GPR30 was only detected in the RV, and it was not affected by PH in MA female ApoE-deficient mice.ConclusionsOur results suggest that only aging female ApoE-deficient but not WT mice develop severe PH compared to younger females. Exogenous estrogen therapy rescued PH and RV hypertrophy in aging female ApoE-deficient mice possibly through restoration of lung ERβ

Pregnancy is associated with decreased cardiac proteasome activity and oxidative stress in mice.

During pregnancy, the heart develops physiological hypertrophy. Proteasomal degradation has been shown to be altered in various models of pathological cardiac hypertrophy. Since the molecular signature of pregnancy-induced heart hypertrophy differs significantly from that of pathological heart hypertrophy, we investigated whether the cardiac proteasomal proteolytic pathway is affected by pregnancy in mice. We measured the proteasome activity, expression of proteasome subunits, ubiquitination levels and reactive oxygen production in the hearts of four groups of female mice: i) non pregnant (NP) at diestrus stage, ii) late pregnant (LP), iii) one day post-partum (PP1) and iv) 7 days post-partum (PP7). The activities of the 26 S proteasome subunits β1 (caspase-like), and β2 (trypsin-like) were significantly decreased in LP (β1∶83.26 ± 1.96%; β2∶74.74 ± 1.7%, normalized to NP) whereas β5 (chymotrypsin-like) activity was not altered by pregnancy but significantly decreased 1 day post-partum. Interestingly, all three proteolytic activities of the proteasome were restored to normal levels 7 days post-partum. The decrease in proteasome activity in LP was not due to the surge of estrogen as estrogen treatment of ovariectomized mice did not alter the 26 S proteasome activity. The transcript and protein levels of RPN2 and RPT4 (subunits of 19 S), β2 and α7 (subunits of 20 S) as well as PA28α and β5i (protein only) were not significantly different among the four groups. High resolution confocal microscopy revealed that nuclear localization of both core (20S) and RPT4 in LP is increased ∼2-fold and is fully reversed in PP7. Pregnancy was also associated with decreased production of reactive oxygen species and ubiquitinated protein levels, while the de-ubiquitination activity was not altered by pregnancy or parturition. These results indicate that late pregnancy is associated with decreased ubiquitin-proteasome proteolytic activity and oxidative stress

Management of ST Elevation Myocardial Infarction (STEMI) in Different Settings

AbstractST-segment elevation myocardial infarction (STEMI) is a life-threatening condition that requires emergent, complex, well-coordinated treatment. Although the primary goal of treatment is simple to describe—reperfusion as quickly as possible—the management process is complicated and is affected by multiple factors including location, patient, and practitioner characteristics. Hence, this narrative review will discuss the recommended management and treatment strategies of STEMI in the circumstances.</jats:p

Pregnancy is associated with decreased cardiac proteasome activity and oxidative stress in mice.

During pregnancy, the heart develops physiological hypertrophy. Proteasomal degradation has been shown to be altered in various models of pathological cardiac hypertrophy. Since the molecular signature of pregnancy-induced heart hypertrophy differs significantly from that of pathological heart hypertrophy, we investigated whether the cardiac proteasomal proteolytic pathway is affected by pregnancy in mice. We measured the proteasome activity, expression of proteasome subunits, ubiquitination levels and reactive oxygen production in the hearts of four groups of female mice: i) non pregnant (NP) at diestrus stage, ii) late pregnant (LP), iii) one day post-partum (PP1) and iv) 7 days post-partum (PP7). The activities of the 26 S proteasome subunits β1 (caspase-like), and β2 (trypsin-like) were significantly decreased in LP (β1∶83.26 ± 1.96%; β2∶74.74 ± 1.7%, normalized to NP) whereas β5 (chymotrypsin-like) activity was not altered by pregnancy but significantly decreased 1 day post-partum. Interestingly, all three proteolytic activities of the proteasome were restored to normal levels 7 days post-partum. The decrease in proteasome activity in LP was not due to the surge of estrogen as estrogen treatment of ovariectomized mice did not alter the 26 S proteasome activity. The transcript and protein levels of RPN2 and RPT4 (subunits of 19 S), β2 and α7 (subunits of 20 S) as well as PA28α and β5i (protein only) were not significantly different among the four groups. High resolution confocal microscopy revealed that nuclear localization of both core (20S) and RPT4 in LP is increased ∼2-fold and is fully reversed in PP7. Pregnancy was also associated with decreased production of reactive oxygen species and ubiquitinated protein levels, while the de-ubiquitination activity was not altered by pregnancy or parturition. These results indicate that late pregnancy is associated with decreased ubiquitin-proteasome proteolytic activity and oxidative stress

Abstract P130: Estrogen Receptor β Mediates the Rescue of Cardiac Function in Advanced Heart Failure by Promoting Neoangiogenesis and Reducing Fibrosis

Estrogen can act via the estrogen receptor alpha (ERa) or estrogen receptor beta (ERb) to exert its biological effects, and both of these receptors are present in the heart. We have previously shown that short-term estrogen (E2) treatment can rescue pressure overload-induced decompensated heart failure (HF) in mice, and that this rescue is achieved mainly through the ERb. Furthermore, E2 has been shown to regulate angiogenesis in different tissues. Because HF has been associated with decreased angiogenesis and increased fibrosis, here we investigated whether the E2-induced rescue of HF by the selective ERb agonist DPN can regulate cardiac fibrosis and neoangiogenesis. We used transaortic constriction to induce HF, and once the ejection fraction (EF) reached ∼30%, one group of animals was sacrificed (HF group), and the other three groups received either 17b-estradiol via a subcutaneous pellet implant (0.012mg/pellet, n=16), selective ERa agonist (PPT, 0.625mg/kg/day), or selective ERb agonist (DPN, 0.625mg/kg/day) for 10 days. Serial echocardiography was performed to monitor cardiac structure and function. As expected, E2 rescued HF by restoring EF from 33.17±1.12% to 53.05±1.29%. Mice treated with DPN had a significant EF improvement from 33.17±1.12% to 45.25±2.1% (n=7), while the EF of PPT-treated mice did not improve (31.09±2.3%, n=6). Similarly, only the fractional shortening of DPN-treated mice improved from 15.7±0.58% in HF to 21.95±1.65% with DPN treatment vs. 14.72±1.24% with PPT. Next, we examined whether promotion of cardiac neoangiogenesis and suppression of fibrosis by the selective ERb agonist are possible mechanisms in the rescue action of HF by DPN. DPN treatment was able to reverse the interstitial and perivascular fibrosis observed in HF, while PPT had no effect. The selective ERb agonist also stimulated neoangiogenesis, as the capillary density was increased from 0.46±0.04 microvessels/cardiomyocyte in HF to 0.67±0.07 with DPN treatment, whereas PPT treatment had no effect (0.43±0.03). Our data strongly suggests that upregulation of cardiac neoangiogenesis and reversal of fibrosis are pivotal mechanisms in rescuing advanced HF by the estrogen receptor beta agonist DPN.</jats:p