Cytomegalovirus Infection Causes an Increase of Arterial Blood Pressure

Cytomegalovirus (CMV) infection is a common infection in adults (seropositive 60–99% globally), and is associated with cardiovascular diseases, in line with risk factors such as hypertension and atherosclerosis. Several viral infections are linked to hypertension, including human herpes virus 8 (HHV-8) and HIV-1. The mechanisms of how viral infection contributes to hypertension or increased blood pressure are not defined. In this report, the role of CMV infection as a cause of increased blood pressure and in forming aortic atherosclerotic plaques is examined. Using in vivo mouse model and in vitro molecular biology analyses, we find that CMV infection alone caused a significant increase in arterial blood pressure (ABp) (p<0.01 $\sim$0.05), measured by microtip catheter technique. This increase in blood pressure by mouse CMV (MCMV) was independent of atherosclerotic plaque formation in the aorta, defined by histological analyses. MCMV DNA was detected in blood vessel samples of viral infected mice but not in the control mice by nested PCR assay. MCMV significantly increased expression of pro-inflammatory cytokines IL-6, TNF-$\alpha$, and MCP-1 in mouse serum by enzyme-linked immunosorbent assay (ELISA). Using quantitative real time reverse transcriptase PCR (Q-RT-PCR) and Western blot, we find that CMV stimulated expression of renin in mouse and human cells in an infectious dose-dependent manner. Co-staining and immunofluorescent microscopy analyses showed that MCMV infection stimulated renin expression at a single cell level. Further examination of angiotensin-II (Ang II) in mouse serum and arterial tissues with ELISA showed an increased expression of Ang II by MCMV infection. Consistent with the findings of the mouse trial, human CMV (HCMV) infection of blood vessel endothelial cells (EC) induced renin expression in a non-lytic infection manner. Viral replication kinetics and plaque formation assay showed that an active, CMV persistent infection in EC and expression of viral genes might underpin the molecular mechanism. These results show that CMV infection is a risk factor for increased arterial blood pressure, and is a co-factor in aortic atherosclerosis. Viral persistent infection of EC may underlie the mechanism. Control of CMV infection can be developed to restrict hypertension and atherosclerosis in the cardiovascular system

H2O2-responsive molecularly engineered polymer nanoparticles as ischemia/reperfusion-targeted nanotherapeutic agents

The main culprit in the pathogenesis of ischemia/reperfusion (I/R) injury is the overproduction of reactive oxygen species (ROS). Hydrogen peroxide (H2O2), the most abundant form of ROS produced during I/R, causes inflammation, apoptosis and subsequent tissue damages. Here, we report H2O2-responsive antioxidant nanoparticles formulated from copolyoxalate containing vanillyl alcohol (VA) (PVAX) as a novel I/R-targeted nanotherapeutic agent. PVAX was designed to incorporate VA and H2O2-responsive peroxalate ester linkages covalently in its backbone. PVAX nanoparticles therefore degrade and release VA, which is able to reduce the generation of ROS, and exert anti-inflammatory and anti-apoptotic activity. In hind-limb I/R and liver I/R models in mice, PVAX nanoparticles specifically reacted with overproduced H2O2 and exerted highly potent anti-inflammatory and anti-apoptotic activities that reduced cellular damages. Therefore, PVAX nanoparticles have tremendous potential as nanotherapeutic agents for I/R injury and H2O2-associated diseases

Abnormal Calcium Handling and Exaggerated Cardiac Dysfunction in Mice with Defective Vitamin D Signaling

Aim Altered vitamin D signaling is associated with cardiac dysfunction, but the pathogenic mechanism is not clearly understood. We examine the mechanism and the role of vitamin D signaling in the development of cardiac dysfunction. Methods and Results: We analyzed 1α-hydroxylase (1α-OHase) knockout (1α-OHase−/−) mice, which lack 1α-OH enzymes that convert the inactive form to hormonally active form of vitamin D. 1α-OHase−/− mice showed modest cardiac hypertrophy at baseline. Induction of pressure overload by transverse aortic constriction (TAC) demonstrated exaggerated cardiac dysfunction in 1α-OHase−/− mice compared to their WT littermates with a significant increase in fibrosis and expression of inflammatory cytokines. Analysis of calcium (Ca2+) transient demonstrated profound Ca2+ handling abnormalities in 1α-OHase−/− mouse cardiomyocytes (CMs), and treatment with paricalcitol (PC), an activated vitamin D3 analog, significantly attenuated defective Ca2+ handling in 1α-OHase−/− CMs. We further delineated the effect of vitamin D deficiency condition to TAC by first correcting the vitamin D deficiency in 1α-OHase−/− mice, followed then by either a daily maintenance dose of vitamin D or vehicle (to achieve vitamin D deficiency) at the time of sham or TAC. In mice treated with vitamin D, there was a significant attenuation of TAC-induced cardiac hypertrophy, interstitial fibrosis, inflammatory markers, Ca2+ handling abnormalities and cardiac function compared to the vehicle treated animals. Conclusions: Our results provide insight into the mechanism of cardiac dysfunction, which is associated with severely defective Ca2+ handling and defective vitamin D signaling in 1α-OHase−/− mice

Hydrogen peroxide-activatable antioxidant prodrug as a targeted therapeutic agent for ischemia-reperfusion injury

Overproduction of hydrogen peroxide (H2O2) causes oxidative stress and is the main culprit in the pathogenesis of ischemia/reperfusion (I/R) injury. Suppression of oxidative stress is therefore critical in the treatment of I/R injury. Here, we report H2O2-activatable antioxidant prodrug (BRAP) that is capable of specifically targeting the site of oxidative stress and exerting anti-inflammatory and anti-apoptotic activities. BRAP with a self-immolative boronic ester protecting group was designed to scavenge H2O2 and release HBA (p-hydroxybenzyl alcohol) with antioxidant and anti-inflammatory activities. BRAP exerted potent antioxidant and anti-inflammatory activity in lipopolysaccharide (LPS)- and H2O2-stimulated cells by suppressing the generation of ROS and pro-inflammatory cytokines. In mouse models of hepatic I/R and cardiac I/R, BRAP exerted potent antioxidant, anti-inflammatory and anti-apoptotic activities due to the synergistic effects of H2O2-scavenging boronic esters and therapeutic HBA. In addition, administration of high doses of BRAP daily for 7 days showed no renal or hepatic function abnormalities. Therefore BRAP has tremendous therapeutic potential as H2O2-activatable antioxidant prodrug for the treatment of I/R injuries

Endothelin A Receptor Antagonist, Atrasentan, Attenuates Renal and Cardiac Dysfunction in Dahl Salt-Hypertensive Rats in a Blood Pressure Independent Manner

Proteinuria is a hallmark of chronic kidney disease (CKD) and cardiovascular disease (CVD), and a good predictor of clinical outcome. Selective endothelin A (ETA) receptor antagonist used with renin-angiotensin system (RAS) inhibitors prevents development of proteinuria in CKD. However, whether the improvement in proteinuria would have beneficial effects on CVD, independent of RAS inhibition, is not well understood. In this study, we investigated whether atrasentan, an ETA receptor antagonist, has renal and cardiovascular effects independent of RAS inhibition. Male Dahl salt sensitive (DSS) rats, at six weeks of age, received water with or without different doses of atrasentan and/or enalapril under high salt (HS) diet or normal diet (ND) for 6 weeks. At the end of 12th week, atrasentan at a moderate dose significantly attenuated proteinuria and serum creatinine without reducing mean arterial pressure (MAP), thereby preventing cardiac hypertrophy and improving cardiac function. ACE inhibitor enalapril at a dose that did not significantly lowered BP, attenuated cardiac hypertrophy while moderately improving cardiac function without reducing proteinuria and serum creatinine level. Nonetheless, combined therapy of atrasentan and enalapril that does not altering BP exerted additional cardioprotective effect. Based on these findings, we conclude that BP independent monotherapy of ETA receptor antagonist attenuates the progression of CKD and significantly mitigates CVD independent of RAS inhibition

Cytomegalovirus infection causes an increase of arterial blood pressure.

Cytomegalovirus (CMV) infection is a common infection in adults (seropositive 60-99% globally), and is associated with cardiovascular diseases, in line with risk factors such as hypertension and atherosclerosis. Several viral infections are linked to hypertension, including human herpes virus 8 (HHV-8) and HIV-1. The mechanisms of how viral infection contributes to hypertension or increased blood pressure are not defined. In this report, the role of CMV infection as a cause of increased blood pressure and in forming aortic atherosclerotic plaques is examined. Using in vivo mouse model and in vitro molecular biology analyses, we find that CMV infection alone caused a significant increase in arterial blood pressure (ABp) (p<0.01 approximately 0.05), measured by microtip catheter technique. This increase in blood pressure by mouse CMV (MCMV) was independent of atherosclerotic plaque formation in the aorta, defined by histological analyses. MCMV DNA was detected in blood vessel samples of viral infected mice but not in the control mice by nested PCR assay. MCMV significantly increased expression of pro-inflammatory cytokines IL-6, TNF-alpha, and MCP-1 in mouse serum by enzyme-linked immunosorbent assay (ELISA). Using quantitative real time reverse transcriptase PCR (Q-RT-PCR) and Western blot, we find that CMV stimulated expression of renin in mouse and human cells in an infectious dose-dependent manner. Co-staining and immunofluorescent microscopy analyses showed that MCMV infection stimulated renin expression at a single cell level. Further examination of angiotensin-II (Ang II) in mouse serum and arterial tissues with ELISA showed an increased expression of Ang II by MCMV infection. Consistent with the findings of the mouse trial, human CMV (HCMV) infection of blood vessel endothelial cells (EC) induced renin expression in a non-lytic infection manner. Viral replication kinetics and plaque formation assay showed that an active, CMV persistent infection in EC and expression of viral genes might underpin the molecular mechanism. These results show that CMV infection is a risk factor for increased arterial blood pressure, and is a co-factor in aortic atherosclerosis. Viral persistent infection of EC may underlie the mechanism. Control of CMV infection can be developed to restrict hypertension and atherosclerosis in the cardiovascular system

Delayed activation of caspase-independent apoptosis during heart failure in transgenic mice overexpressing caspase inhibitor CrmA

Although caspase activation is generally thought to be necessary to induce apoptosis, recent evidence suggests that apoptosis can be activated in the setting of caspase inhibition. In this study, we tested the hypothesis that caspase-independent apoptotic pathways contribute to the development of heart failure in the absence of caspase activation. Acute cardiomyopathy was induced using a single dose of doxorubicin (Dox, 20 mg/kg) injected into male wild-type (WT) and transgenic (Tg) mice with a cardiac-specific expression of cytokine response modifier A (CrmA), a known caspase inhibitor. Early (6 day) survival was significantly better in CrmA Tg (81%) than WT (38%) mice. Twelve days after Dox injection, however, the mortality benefit had dissipated, and increased cardiac apoptosis was observed in both groups. There was, however, a significantly greater release of apoptosis-inducing factor (AIF) from mitochondria to cytosol in CrmA Tg compared with WT mice, which suggests that an enhancement of activation in caspase-independent apoptotic pathways had occurred. The administration of a poly(ADP-ribose) polymerase-1 inhibitor, 4-amino-1,8-naphthalimide (4-AN), to Dox-treated mice resulted in significantly improved cardiac function, a significant blockade of AIF released from mitochondria, and decreased cardiac apoptosis. There were also significantly improved survival in WT (18% without 4-AN vs. 89% with 4-AN) and CrmA Tg (13% without 4-AN vs. 93% with 4-AN) mice 12 days after Dox injection. In conclusion, these findings suggest that apoptosis can be induced in the heart lacking caspase activation via caspase-independent pathways and that enabling the inhibition of AIF activation may provide a significant cardiac benefit

Exercise-induced expression of VEGF and salvation of myocardium in the early stage of myocardial infarction

The mechanism of exercise-induced benefit and angiogenesis in ischemic heart disease remains poorly defined. This study was designed to investigate the effects of exercise training on the expression of angiogenic factors and angiogenesis in the infarcted myocardium [myocarial infaction (MI)]. Sixty-three male FVB mice were used for study and were divided into subgroups to test the response to exercise: the time-dependent expression of angiogenic factors to exercise training in normal (group 1; n = 12) and infarcted myocardium (group 2; n = 15) and the exercise-induced angiogenic response in normal and infarcted myocardium (group 3; n = 20) as well as the impact of exercise preconditioning on infarcted myocardium (group 4; n = 26). Exercise training consisted of daily treadmill exercise for 1 h for 3 days. Expression of VEGF and its receptors Flt-1 and Flk-1 was upregulated by exercise training in mice with MI. Exercise-induced VEGF expression in the MI group was higher than that in the sham (control) group. Cell proliferation assessment showed a significantly higher (P < 0.05) number of bromodeoxyuridine-positive cells in post-MI mice in the exercise group as opposed to post-MI mice in the sedentary group. 2,3,5-Triphenyltetrazolium chloride staining revealed a profound difference in the size of MI (18.25 ± 2.93%) in the exercise group versus the sedentary group (29.26 ± 7.64%, P = 0.02). Moreover, exercise preconditioning before MI promoted VEGF expression at both mRNA and protein levels. In conclusion, activation of VEGF and its receptors occurs in the infarcted mice heart in response to exercise, which results in decreased infarct size and improved angiogenesis