Expressions of bradykinin B2-receptor, kallikrein and kininogen mRNAs in the heart are altered in pressure-overload cardiac hypertrophy in mice

Neural-Cardiac Inflammasome Axis after Traumatic Brain Injury

Traumatic brain injury (TBI) affects not only the brain but also peripheral organs like the heart and the lungs, which influences long-term outcomes. A heightened systemic inflammatory response is often induced after TBI, but the underlying pathomechanisms that contribute to co-morbidities remain poorly understood. Here, we investigated whether extracellular vehicles (EVs) containing inflammasome proteins are released after severe controlled cortical impact (CCI) in C57BL/6 mice and cause activation of inflammasomes in the heart that result in tissue damage. The atrium of injured mice at 3 days after TBI showed a significant increase in the levels of the inflammasome proteins AIM2, ASC, caspases-1, -8 and -11, whereas IL-1β was increased in the ventricles. Additionally, the injured cortex showed a significant increase in IL-1β, ASC, caspases-1, -8 and -11 and pyrin at 3 days after injury when compared to the sham. Serum-derived extracellular vesicles (EVs) from injured patients were characterized with nanoparticle tracking analysis and Ella Simple Plex and showed elevated levels of the inflammasome proteins caspase-1, ASC and IL-18. Mass spectrometry of serum-derived EVs from mice after TBI revealed a variety of complement- and cardiovascular-related signaling proteins. Moreover, adoptive transfer of serum-derived EVs from TBI patients resulted in inflammasome activation in cardiac cells in culture. Thus, TBI elicits inflammasome activation, primarily in the atrium, that is mediated, in part, by EVs that contain inflammasome- and complement-related signaling proteins that are released into serum and contribute to peripheral organ systemic inflammation, which increases inflammasome activation in the heart.

Analysis of Syk/PECAM-1 signaling pathway in low shear stress induced atherosclerosis based on ultrasound imaging

BACKGROUND AND OBJECTIVE

Low shear stress (LSS) has been demonstrated to be involved in function of vascular endothelial cells. Here we tested the hypothesis that activation of Syk played an important in LSS-induced atherosclerosis via PECAM-1 signaling pathway.

METHODS

In vitro, primary human umbilical vein endothelial cells (HUVECs) were stimulated with parallel plate flow chamber system for 12h under normal shear stress (NSS, 15dyne/cm²), LSS (5dyne/cm²) and high shear stress (HSS, 25dyne/cm²), respectively, followed by inflammatory response analysis. In vivo, animal models of rat fed atherogenic diet were treated with LSS stimulation by constricting abdominal aorta with a blunted needle (0.6mm in diameter). The spatial distribution of WSS of blood vessels was generated by WSS quantitative analysis software through color Doppler flow imaging with a high-frequency small animal ultrasound system. Small molecule R406, a well-demonstrated Syk inhibitor, was applied to animals as well as HUVEC cells.

RESULTS

In vivo, comparison with the control group was performed, the mean value of WSS distribution of blood vessels was lower in LSS model rat. LSS promoted expression of phosphorylated PECAM-1 (p-PECAM-1) and Syk in LSS model rats. Compared with control group, endothelial cells of the abdominal aorta become less elongated and more polygonal in LSS group, and had a slender shape in LSS with R406 group. In vitro, LSS increased the expression of p-PECAM-1, Syk and NF-κB in HUVECs. Inhibition of Syk attenuated LSS-induced inflammatory response.

CONCLUSIONS

Activation of Syk resulted in LSS-induced inflammatory response via PECAM-1 signaling pathway both in vitro and in vivo. Syk might be involved in morphological changes of ECs under the influence of LSS.

Pressure overload-induced cardiac hypertrophy response requires janus kinase 2-histone deacetylase 2 signaling

Pressure overload induces cardiac hypertrophy through activation of Janus kinase 2 (Jak2), however, the underlying mechanisms remain largely unknown. In the current study, we tested whether histone deacetylase 2 (HDAC2) was involved in the process. We found that angiotensin II (Ang-II)-induced re-expression of fetal genes (Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP)) in cultured cardiomyocytes was prevented by the Jak2 inhibitor AG-490 and HDAC2 inhibitor Trichostatin-A (TSA), or by Jak2/HDAC2 siRNA knockdown. On the other hand, myocardial cells with Jak2 or HDAC2 over-expression were hyper-sensitive to Ang-II. In vivo, pressure overload by transverse aorta binding (AB) induced a significant cardiac hypertrophic response as well as re-expression of ANP and BNP in mice heart, which were markedly reduced by AG-490 and TSA. Significantly, AG-490, the Jak2 inhibitor, largely suppressed pressure overload-/Ang-II-induced HDAC2 nuclear exportation in vivo and in vitro. Meanwhile, TSA or HDAC2 siRNA knockdown reduced Ang-II-induced ANP/BNP expression in Jak2 over-expressed H9c2 cardiomyocytes. Together, these results suggest that HDAC2 might be a downstream effector of Jak2 to mediate cardiac hypertrophic response by pressure overload or Ang-II.

Angiotensin II stimulates endothelial NO synthase phosphorylation in thoracic aorta of mice with abdominal aortic banding via type 2 receptor

Abdominal aortic banding in mice induces upregulation of angiotensin II (Ang II) type 2 (AT2) receptors in the pressure-overloaded thoracic aorta. To clarify mechanisms underlying the vascular AT2 receptor-dependent NO production, we measured aortic levels of endothelial NO synthase (eNOS), eNOS phosphorylated at Ser633 and Ser1177, protein kinase B (Akt), and Akt phosphorylated at Ser473 in thoracic aortas of mice after banding. Total eNOS, both forms of phosphorylated eNOS, Akt, and phosphorylated Akt levels, as well as cGMP contents, were significantly increased 4 days after banding. The administration of PD123319 (an AT2 receptor antagonist) or icatibant (a bradykinin B2 receptor antagonist) abolished the banding-induced upregulation of both forms of phosphorylated eNOS, as well as elevation of cGMP, but did not affect the upregulation of eNOS, Akt, and phosphorylated Akt. In the in vitro experiments using aortic rings prepared from banded mice, Ang II produced significant increases in both forms of phosphorylated eNOS, as well as cGMP, and these effects were blocked by PD123319 and icatibant. Ang II-induced eNOS phosphorylation and cGMP elevation in aortic rings were inhibited by protein kinase A (PKA) inhibitors H89 and KT5720 but not by phosphatidylinositol 3-kinase inhibitors wortmannin and LY24002. The contractile response to Ang II was attenuated in aortic rings from banded mice via AT2 receptor, and this attenuation was blocked by PKA inhibitors. These results suggest that the activation of AT2 receptor by Ang II induces phosphorylation of eNOS at Ser633 and Ser1177 via a PKA-mediated signaling pathway, resulting in sustained activation of eNOS.

Stimulation of cyclic GMP production via AT2 and B2 receptors in the pressure-overloaded aorta after banding

Abdominal aortic banding induces upregulation of the angiotensin II (Ang II) type-2 (AT2) receptor, thereby decreasing the contractile response to Ang II in the thoracic aorta of the rat. The aim of this study was to use a mouse model to clarify the mechanisms by which the banding elicits upregulation of the aortic AT2 receptor and the subsequent attenuation of Ang II responsiveness. Concomitantly with the elevation in blood pressure and plasma renin concentration after banding, AT2-receptor mRNA levels in the thoracic aorta rapidly increased in mice within 4 days. Upregulation of the AT2 receptor, as well as blood pressure elevation after banding, was abolished by losartan administration. The contractile response to Ang II was depressed in aortic rings of banding mice but not of sham mice, and was restored by either the AT2-receptor antagonist PD123319 or the bradykinin B2-receptor antagonist icatibant. cGMP content in the thoracic aorta of banding mice was 9-fold greater than that of sham mice, and the elevation was reduced to sham levels 1 hour after intravenous injection of PD123319 or icatibant. When aortic rings were incubated with Ang II, cGMP content increased in banding rings but not in sham rings; the pretreatment with PD123319 or icatibant inhibited Ang II-induced cGMP production. These results suggest that aortic banding induces upregulation of the AT2 receptor through increased circulating Ang II via the AT1 receptor, thereby activating a vasodilatory pathway in vessels through the AT2 receptor via the kinin/cGMP system.

B2 bradykinin receptor (B2BKR) polymorphism and change in left ventricular mass in response to antihypertensive treatment: results from the Swedish Irbesartan Left Ventricular Hypertrophy Investigation versus Atenolol (SILVHIA) trial

OBJECTIVE

Hypertension is associated with a number of adverse morphologic and functional changes in the cardiovascular system, including left ventricular (LV) hypertrophy. Studies have demonstrated that bradykinin, through the B2 bradykinin receptor (B2BKR), mediates important cardiovascular effects that may protect against LV hypertrophy. Recently, a +9/-9 exon 1 polymorphism of the B2BKR was shown to be strongly associated with LV growth response among normotensive males undergoing physical training. We aimed to clarify whether the processes found in exercise-induced LV growth in normotensive people also occur in pathological LV hypertrophy.

DESIGN AND METHODS

We determined the B2BKR genotype of 90 patients with essential hypertension and echocardiographically diagnosed LV hypertrophy, included in a double-blind study to receive treatment for 48 weeks with either the angiotensin II type 1 (AT1) receptor antagonist irbesartan or the beta1-adrenoceptor antagonist atenolol.

RESULTS

B2BKR +9/+9 genotypes responded poorly in LV mass regression, independent of blood pressure reduction or treatment, as compared to the other genotypes (adjusted mean change in LV mass index = -10.0 +/- 4.6 versus -21.6 +/- 2.2 g/m2, P = 0.03).

CONCLUSIONS

Our results suggest an impact of the B2BKR polymorphism on LV mass regression during antihypertensive treatment.

Regulation of cardiac bradykinin B1- and B2-receptor mRNA in experimental ischemic, diabetic, and pressure-overload-induced cardiomyopathy

Although kinins have been associated with the regulation of cardiovascular function in left ventricular hypertrophy (LVH) as a consequence of hypertension, myocardial infarction (MI), and/or diabetic cardiomyopathy, less is known about their receptor regulation under these conditions. We have therefore investigated the bradykinin B1-receptor (B1R) and B2-receptor (B2R) mRNA expression in rat models of MI, LVH and diabetes mellitus (DM). Sprague-Dawley rats (SD) were submitted to permanent ligation of the left descending coronary artery (LAD) to induce a MI, whereas DM was induced by a single injection of streptozotocin (STZ). LVH was induced after thoracic aortic banding (AB). Three weeks after MI, six weeks after STZ injection or six weeks after AB, left ventricular (LV) function was characterized using a Millar-tip catheter. Cardiac B1R- and B2R-mRNA expression were analyzed by specific RNase-protection assays (RPA). LV contractility (dP/dt max) was impaired by 40-48% in rats after induction of MI or DM compared to their controls. However, despite an enormous increase in LV end-diastolic pressure (LEVDP) to 310% after AB, LV contractility did not differ compared to the controls. These hemodynamic changes were accompanied by an up-regulation of cardiac B1R- (MI, 288%; STZ, 215%; AB, 4180%) and B2R-mRNA expression (MI, 122%; STZ, 288%; AB, 96%). Up-regulation of both BK-receptor (BKR) types in early stages of cardiac wound healing induced by ischemia and in chronic stages of cardiac remodeling induced by pressure-overload or by hyperglycemia indicates that kinins play a major role in the complex processes of cardiac tissue injury and repair.

Differential gene expression in the rat soleus muscle during early work overload-induced hypertrophy

Delineating the molecular mechanisms that are responsive to work overload is crucial to understanding the adaptive processes controlling skeletal muscle mass. We have examined the molecular events associated with increased workload by using microarray analysis to begin to define the mechanotransduction responsive transcription programs in skeletal muscle. Microarray analysis identified 112 mRNAs that were expressed differentially in the soleus muscle of sham-operated vs. gastrocnemius-ablated rats. These genes can be classified into cell proliferation, autocrine/paracrine, extracellular matrix, immune response, intracellular signaling, metabolism, neural, protein synthesis/degradation, structural, and transcription. These findings dramatically increase the number of known, differentially expressed mRNA during early skeletal muscle hypertrophy. In toto, our findings indicate that work overload induced skeletal muscle hypertrophy alters autocrine/paracrine signaling, intracellular signaling, and transcription factor expression, which likely results in a dramatic change in cellular metabolism, cell proliferation, and muscle structure. These data enhance our understanding of the complex molecular mechanisms controlling skeletal muscle mass in response to increased physical activity.