Collagen networks within 3D PEG hydrogels support valvular interstitial cell matrix mineralization

Enzymatically degradable hydrogels were designed for the 3D culture of valvular interstitial cells (VICs), and through the incorporation of various functionalities, we aimed to investigate the role of the tissue microenvironment in promoting the osteogenic properties of VICs and matrix mineralization. Specifically, porcine VICs were encapsulated in a poly(ethylene glycol) hydrogel crosslinked with a matrix metalloproteinase (MMP)-degradable crosslinker (KCGPQG↓IWGQCK) and formed via a thiol-ene photoclick reaction in the presence or absence of collagen type I to promote matrix mineralization. VIC-laden hydrogels were treated with osteogenic medium for up to 15 days, and the osteogenic response was characterized by the expression of RUNX2 as an early marker of an osteoblast-like phenotype, osteocalcin (OCN) as a marker of a mature osteoblast-like phenotype, and vimentin (VIM) as a marker of the fibroblast phenotype. In addition, matrix mineralization was characterized histologically with Von Kossa stain for calcium phosphate. Osteogenic response was further characterized biochemically with calcium assays, and physically via optical density measurements. When the osteogenic medium was supplemented with calcium chloride, OCN expression was upregulated and mineralization was discernable at 12 days of culture. Finally, this platform was used to screen various drug therapeutics that were assessed for their efficacy in preventing mineralization using optical density as a higher throughput readout. Collectively, these results suggest that matrix composition has a key role in supporting mineralization deposition within diseased valve tissue.

Failure to vasodilate in response to salt loading blunts renal blood flow and causes salt-sensitive hypertension

AIMS

Salt-sensitive (SS) hypertension is accompanied by impaired vasodilation in the systemic and renal circulation. However, the causal relationship between vascular dysfunction and salt-induced hypertension remains controversial. We sought to determine whether primary vascular dysfunction, characterized by a failure to vasodilate during salt loading, plays a causal role in the pathogenesis of SS hypertension.

METHODS AND RESULTS

Mice selectively expressing a peroxisome proliferator-activated receptor γ dominant-negative mutation in vascular smooth muscle (S-P467L) exhibited progressive SS hypertension during a 4 week high salt diet (HSD). This was associated with severely impaired vasodilation in systemic and renal vessels. Salt-induced impairment of vasodilation occurred as early as 3 days after HSD, which preceded the onset of SS hypertension. Notably, the overt salt-induced hypertension in S-P467L mice was not driven by higher cardiac output, implying elevations in peripheral vascular resistance. In keeping with this, HSD-fed S-P467L mice exhibited decreased smooth muscle responsiveness to nitric oxide (NO) in systemic vessels. HSD-fed S-P467L mice also exhibited elevated albuminuria and a blunted increase in urinary NO metabolites which was associated with blunted renal blood flow and increased sodium retention mediated by a lack of HSD-induced suppression of NKCC2. Blocking NKCC2 function prevented the salt-induced increase in blood pressure in S-P467L mice.

CONCLUSION

We conclude that failure to vasodilate in response to salt loading causes SS hypertension by restricting renal perfusion and reducing renal NO through a mechanism involving NKCC2 in a mouse model of vascular peroxisome proliferator-activated receptor γ impairment.

Calcium Signaling Regulates Valvular Interstitial Cell Alignment and Myofibroblast Activation in Fast-Relaxing Boronate Hydrogels

The role viscoelasticity in fibrotic disease progression is an emerging area of interest. Here, a fast-relaxing hydrogel system is exploited to investigate potential crosstalk between calcium signaling and mechanotransduction. Poly(ethylene glycol) (PEG) hydrogels containing boronate and triazole crosslinkers are synthesized, with varying ratios of boronate to triazole crosslinks to systematically vary the extent of stress relaxation. Valvular interstitial cells (VICs) encapsulated in hydrogels with the highest levels of stress relaxation (90%) exhibit a spread morphology by day 1 and are highly aligned (80 ± 2%) by day 5. Key myofibroblast markers, including α-smooth muscle actin (αSMA) and collagen 1a1 (COL1A1), are significantly elevated. VIC myofibroblast activation decreases by 42 ± 18% through inhibition of mechanotransduction, independently of VIC morphology and alignment. Calcium signaling through a transient receptor potential vanilloid 4 (TRPV4) is found to regulate VIC spreading, alignment, and activation in a time dependent manner. Inhibition of calcium signaling at early time points results in disturbed cell alignment, decreased mechanotransduction, and diminished activation, while inhibition at later time points only causes partially reduced myofibroblast activation. These results suggest a potential crosstalk mechanism, where calcium signaling acts upstream of mechanosensing and can regulate VIC myofibroblast activation independently of mechanotransduction.

Mitochondrial pyruvate carriers are required for myocardial stress adaptation

In addition to fatty acids, glucose and lactate are important myocardial substrates under physiologic and stress conditions. They are metabolized to pyruvate, which enters mitochondria via the mitochondrial pyruvate carrier (MPC) for citric acid cycle metabolism. In the present study, we show that MPC-mediated mitochondrial pyruvate utilization is essential for the partitioning of glucose-derived cytosolic metabolic intermediates, which modulate myocardial stress adaptation. Mice with cardiomyocyte-restricted deletion of subunit 1 of MPC (cMPC1^-/-) developed age-dependent pathologic cardiac hypertrophy, transitioning to a dilated cardiomyopathy and premature death. Hypertrophied hearts accumulated lactate, pyruvate and glycogen, and displayed increased protein O-linked N-acetylglucosamine, which was prevented by increasing availability of non-glucose substrates in vivo by a ketogenic diet (KD) or a high-fat diet, which reversed the structural, metabolic and functional remodelling of non-stressed cMPC1^-/- hearts. Although concurrent short-term KDs did not rescue cMPC1^-/- hearts from rapid decompensation and early mortality after pressure overload, 3 weeks of a KD before transverse aortic constriction was sufficient to rescue this phenotype. Together, our results highlight the centrality of pyruvate metabolism to myocardial metabolism and function.

Secreted Factors From Proinflammatory Macrophages Promote an Osteoblast-Like Phenotype in Valvular Interstitial Cells

OBJECTIVE

Resident valvular interstitial cells (VICs) activate to myofibroblasts during aortic valve stenosis progression, which further promotes fibrosis or even differentiate into osteoblast-like cells that can lead to calcification of valve tissue. Inflammation is a hallmark of aortic valve stenosis, so we aimed to determine proinflammatory cytokines secreted from M1 macrophages that give rise to a transient VIC phenotype that leads to calcification of valve tissue. Approach and Results: We designed hydrogel biomaterials as valve extracellular matrix mimics enabling the culture of VICs in either their quiescent fibroblast or activated myofibroblast phenotype in response to the local matrix stiffness. When VIC fibroblasts and myofibroblasts were treated with conditioned media from THP-1-derived M1 macrophages, we observed robust reduction of αSMA (alpha smooth muscle actin) expression, reduced stress fiber formation, and increased proliferation, suggesting a potent antifibrotic effect. We further identified TNF (tumor necrosis factor)-α and IL (interleukin)-1β as 2 cytokines in M1 media that cause the observed antifibrotic effect. After 7 days of culture in M1 conditioned media, VICs began differentiating into osteoblast-like cells, as measured by increased expression of RUNX2 (runt-related transcription factor 2) and osteopontin. We also identified and validated IL-6 as a critical mediator of the observed pro-osteogenic effect.

CONCLUSIONS

Proinflammatory cytokines in M1 conditioned media inhibit myofibroblast activation in VICs (eg, TNF-α and IL-1β) and promote their osteogenic differentiation (eg, IL-6). Together, our work suggests inflammatory M1 macrophages may drive a myofibroblast-to-osteogenic intermediate VIC phenotype, which may mediate the switch from fibrosis to calcification during aortic valve stenosis progression.

An Injectable Microparticle Formulation Provides Long-Term Inhibition of Hypothalamic ERK1/2 Activity and Sympathetic Excitation in Rats with Heart Failure

Sympathetic excitation contributes to clinical deterioration in systolic heart failure (HF). Significant inhibition of hypothalamic paraventricular nucleus (PVN) ERK1/2 signaling and a subsequent reduction of plasma norepinephrine (NE) levels in HF rats were achieved 2 weeks after a single subcutaneous injection of PD98059-loaded polymeric microparticles, without apparent adverse events, while blank microparticles had no effect. Similar reductions in plasma NE, a general indicator of sympathetic excitation, were previously achieved in HF rats by intracerebroventricular infusion of PD98059 or genetic knockdown of PVN ERK1/2 expression. This study presents a clinically feasible therapeutic approach to the central abnormalities contributing to HF progression.

Abstract 359: Cardiac-specific Deletion of Prohibitin-1 Leads to Fetal Demise, Gross Mitochondrial Abnormalities and Heart Failure in Adolescent Mice

Prohibitins (PHB1, 2) are lipid raft-associated proteins which form a multimeric, alternating ring-like structure in cellular membranes, and are particularly abundant in mitochondria and plasma membranes, but have also been found in nuclei. These pleiotropic proteins are associated with numerous signaling pathways responsible for cell differentiation, growth, and metabolism. In mitochondria, PHBs are thought to act as scaffold-like chaperone proteins responsible for stabilizing enzymes responsible for electron transport and oxidative phosphorylation (OXPHOS), minimizing reactive oxygen species (ROS), and coordinating fission/fusion. However, the extent to which PHB1 regulates mitochondria and electromechanical function of the heart, is not known. We established a cardiac-specific PHB1-deficient mouse strain by crossing floxxed phb1 mice with mice expressing Cre recombinase under control of myosin heavy chain (MHC) promoter. The vast majority of cardiac-specific PHB1-deficient mice (cPHB1ko) died in utero during pregnancy (E12-E15). Uterine sonography of the expired cPHB1ko embryos showed significantly decreased crown-rump length and increased placenta thickness with large amount of fluids, restricted uterine artery flow and detachment between amnion and chorion compared with normal embryos (P < 0.001). The few that were born develop severe dilated cardiomyopathy, resulting in mortality by 8-9 weeks of age. Heart weight/body weight ratio is ~2-fold greater in the KO mice vs. WT. Echocardiography reveals severely enlarged right atria and ventricles in cPHB1ko mice, corresponding to significantly decreased ejection faction (EF), increased end diastolic volume (EDV) and end systolic volume (ESV) compared to wild-type littermates (P < 0.05). In mitochondria, cPHB1ko mice have derangements in OXPHOS as evidenced by decreased pyruvate and palmitoylcarnitine-supported respiration and ATP production. Moreover, both the rate of calcium uptake (P = 0.05) and the total calcium retention capacity (P < 0.01) were diminished in the KO mice. These preliminary findings implicate PHB1 as a critical regulator of myocardial development and function, due in part to its role in maintaining OXPHOS and controlling metabolism.

An injectable microparticle formulation for the sustained release of the specific MEK inhibitor PD98059: in vitro evaluation and pharmacokinetics

PD98059 is a reversible MEK inhibitor that we are investigating as a potential treatment for neurochemical changes in the brain that drive neurohumoral excitation in heart failure. In a rat model that closely resembles human heart failure, we found that central administration of PD98059 inhibits phosphorylation of ERK1/2 in the paraventricular nucleus of the hypothalamus, ultimately reducing sympathetic excitation which is a major contributor to clinical deterioration. Studies revealed that the pharmacokinetics and biodistribution of PD98059 match a two-compartment model, with drug found in brain as well as other body tissues, but with a short elimination half-life in plasma (approximately 73 min) that would severely limit its potential clinical usefulness in heart failure. To increase its availability to tissues, we prepared a sustained release PD98059-loaded PLGA microparticle formulation, using an emulsion solvent evaporation technique. The average particle size, yield percent, and encapsulation percent were found to be 16.73 μm, 76.6%, and 43%, respectively. In vitro drug release occurred over 4 weeks, with no noticeable burst release. Following subcutaneous injection of the microparticles in rats, steady plasma levels of PD98059 were detected by HPLC for up to 2 weeks. Furthermore, plasma and brain levels of PD98059 in rats with heart failure were detectable by LC/MS, despite expected erratic absorption. These findings suggest that PD98059-loaded microparticles hold promise as a novel therapeutic intervention countering sympathetic excitation in heart failure, and perhaps in other disease processes, including cancers, in which activated MAPK signaling is a significant contributing factor. Graphical abstract.

Insulin receptor substrates differentially exacerbate insulin-mediated left ventricular remodeling

Pressure overload (PO) cardiac hypertrophy and heart failure are associated with generalized insulin resistance and hyperinsulinemia, which may exacerbate left ventricular (LV) remodeling. While PO activates insulin receptor tyrosine kinase activity that is transduced by insulin receptor substrate 1 (IRS1), the present study tested the hypothesis that IRS1 and IRS2 have divergent effects on PO-induced LV remodeling. We therefore subjected mice with cardiomyocyte-restricted deficiency of IRS1 (CIRS1KO) or IRS2 (CIRS2KO) to PO induced by transverse aortic constriction (TAC). In WT mice, TAC-induced LV hypertrophy was associated with hyperactivation of IRS1 and Akt1, but not IRS2 and Akt2. CIRS1KO hearts were resistant to cardiac hypertrophy and heart failure in concert with attenuated Akt1 activation. In contrast, CIRS2KO hearts following TAC developed more severe LV dysfunction than WT controls, and this was prevented by haploinsufficiency of Akt1. Failing human hearts exhibited isoform-specific IRS1 and Akt1 activation, while IRS2 and Akt2 activation were unchanged. Kinomic profiling identified IRS1 as a potential regulator of cardioprotective protein kinase G-mediated signaling. In addition, gene expression profiling revealed that IRS1 signaling may promote a proinflammatory response following PO. Together, these data identify IRS1 and Akt1 as critical signaling nodes that mediate LV remodeling in both mice and humans.

Pharmacological vs Exercise Stress Echocardiography for Detection of Cardiac Allograft Vasculopathy

Objective

To test the hypothesis that exercise and dobutamine would provide levels of cardiac stress that are comparable to those achieved in a general stress test population, and to one another, in heart transplant recipients.

Patients and Methods

From February 10, 2015, to December 31, 2017, 81 patients underwent exercise stress (N=45) or dobutamine stress (N=36) echocardiography at a mean ± SD of 11±14 years (range, 1-29 years) after heart transplant. Hemodynamic and inotropic responses were compared between groups, and to a prior test, longitudinally. The primary outcome was peak heart rate (HR) × systolic blood pressure (SBP).

Results

Peak exercise HR × SBP × 10⁻³ was a mean ± SD of 24.9±4.9 mm Hg/min for exercise stress vs 21.2±3.4 mm Hg/min during dobutamine stress (P<.001). In 35 patients who underwent a dobutamine stress test followed later by another dobutamine stress test, peak HR × SBP changed by 4.2%±16% (P=.05). In 25 patients who underwent a dobutamine stress test followed later by an exercise stress test, peak HR × SBP increased by 12%±23% (P=.002 vs serial dobutamine stress tests). Peak exercise HR did not correlate with time since heart transplant, patient age, or graft age. Peak dobutamine HR correlated modestly with patient age (r²=0.28). Inotropic responses were similar in both groups. Overall, patients preferred exercise stress testing to dobutamine stress tests. Dobutamine stress testing was more expensive than exercise stress tests.

Conclusion

Exercise induces a level of cardiac stress that is equal to or greater than dobutamine-induced stress, at lower cost, in heart transplant recipients who express preference for exercise stress testing.

Abstract P2010: Silencing Epidermal Growth Factor Receptor Reduces P44/42 Mitogen-Activated Protein Kinase Signaling in the Hypothalamic Paraventricular Nucleus and Ameliorates Sympathetic Excitation in Rats With Heart Failure After Myocardial Infarction

The p44/42 mitogen-activated protein kinase (MAPK) signaling pathway is activated in the brain in myocardial infarction (MI)-induced heart failure (HF). Activation of brain p44/42 MAPK signaling can induce endoplasmic reticulum (ER) stress, increase proinflammatory cytokine expression and upregulate renin-angiotensin system (RAS) activity in the brain, contributing to sympathetic excitation. Multiple excitatory agonists (e.g., angiotensin II, aldosterone and pro-inflammatory cytokines) activate brain MAPK signaling in HF, but the mechanisms are poorly understood. We tested the involvement of the epidermal growth factor receptor (EGFR), which has recently been shown to mediate MAPK signaling in peripheral cardiovascular tissues. Male rats received bilateral microinjections of a lentiviral vector encoding a small interfering RNA (siRNA) for EGFR, or a scrambled siRNA, into the hypothalamic paraventricular nucleus (PVN), a critical cardiovascular and autonomic center. One week later, some rats were euthanized to confirm the effectiveness of EGFR knockdown in PVN. mRNA for EGFR was significantly (*P<0.05) lower in rats that received the EGFR siRNA (0.54±0.17* vs 1.10±0.20, fold change). Other rats underwent coronary artery ligation (CL) to induce HF. Four weeks later, HF rats treated with siRNA for EGFR, compared with HF rats treated with scrambled siRNA, had lower protein levels of phosphorylated p44/42 MAPK (0.20±0.08* vs 0.34±0.06), lower mRNA levels of the ER stress markers BIP (0.77±0.10* vs 1.00±0.12) and ATF4 (0.71±0.14* vs 1.03±0.25), the inflammatory mediators TNF-α (0.73±0.11* vs 1.01±0.15), IL-1β (0.65±0.14* vs 1.02±0.21) and COX-2 (0.71±0.16* vs 1.00±0.14), and the RAS components ACE (0.68±0.26* vs 1.06±0.37) and AT 1a R (0.70±0.11* vs 1.03±0.28) in the PVN, lower urinary norepinephrine levels (28±9* vs 39±7 ng/ml), and improved peripheral manifestations of HF as indicated by reduced right ventricular/body weight and lung/body weight and left ventricular end-diastolic pressure. These results suggest that EGFR in the PVN activates p44/42 MAPK, as well as RAS, neuroinflammation and ER stress, in MI-induced HF. Brain EGFR may be a novel target for therapeutic intervention in the MI-induced HF syndrome.

Synergistic inhibition of GP130 and ERK signaling blocks chemoresistant bladder cancer cell growth

Multidrug resistance is a major treatment obstacle for recurrent and metastatic bladder cancer, which often leads to disease progression and poor clinical outcome. Although overexpression of interleukin-6 (IL-6) appears to play a critical role in the development of chemotherapy resistance, inhibitors for IL-6 alone have not improved clinical outcomes. Since the IL-6/IL-6R/GP130 complex is involved in multidrug resistance, another strategy would be to focus on glycoprotein-130 (GP130) since it dimerizes with IL-6R/CD26 as a membrane-bound signaling transducer receptor and initiates subsequent signaling activation and may be a potential therapeutic target. Currently, the role of GP130 in chemoresistant bladder cancer is unknown. In the present study, we demonstrate that GP130 is over-expressed in cisplatin and gemcitabine-resistant bladder cancer cells, and that the inhibition of GP130 expression significantly reduces cell viability, survival and migration. Downstream of GP130 is PI3K/AKT/mTOR signaling, which is inactivated by SC144, a GP130 inhibitor. However, Raf/MEK/ERK signaling, which also is downstream of GP130 is activated by SC144. This activation is likely based on a mTOR/S6K1/PI3K/ERK negative feedback loop, which is presumed to counteract the inhibitory effect of SC144 on tumor aggressiveness. Blocking both GP130 and pERK resulted in synergistic inhibition of cytotoxicity, clonal survival rates and cell migration in our chemotherapy resistant bladder cancer cells. This vertical inhibition offers a novel therapeutic strategy for targeting human chemoresistant bladder cancer.

Brain TACE (Tumor Necrosis Factor-α-Converting Enzyme) Contributes to Sympathetic Excitation in Heart Failure Rats

TNF-α (tumor necrosis factor-α) is initially synthesized as a transmembrane protein that is cleaved by TACE (TNF-α-converting enzyme) to release soluble TNF-α. The elevated level of TNF-α in the brain and circulation in heart failure (HF) suggests an increase in the TACE-mediated ectodomain shedding process. The present study sought to determine whether TACE is upregulated in cardiovascular/autonomic brain regions like subfornical organ and hypothalamic paraventricular nucleus in rats with ischemia-induced HF and whether TACE plays a role in TNF-α-driven sympathetic excitation. We found that TACE was expressed throughout the subfornical organ and paraventricular nucleus, with significantly higher levels in HF than in sham-operated (Sham) rats. Intracerebroventricular injection of recombinant TACE induced a mild increase in blood pressure, heart rate, and renal sympathetic nerve activity that peaked at 15 to 20 minutes in both Sham and HF rats. HF rats had a secondary prolonged increase in these variables that was prevented by the TNF-α inhibitor SPD304. Intracerebroventricular administration of the TACE inhibitor TNF-alpha protease inhibitor 1 decreased blood pressure, heart rate, and renal sympathetic nerve activity in Sham and HF rats, with an exaggerated reduction in heart rate and renal sympathetic nerve activity in the HF rats. Direct microinjection of TACE or TNF-alpha protease inhibitor 1 into paraventricular nucleus or subfornical organ of Sham and HF rats elicited blood pressure, heart rate, and renal sympathetic nerve activity responses similar to intracerebroventricular TACE or TNF-alpha protease inhibitor 1. Intracerebroventricular infusion of Ang II (angiotensin II) and IL (interleukin)-1β increased TACE expression in subfornical organ and paraventricular nucleus of normal rats. These data suggest that a TACE-mediated increase in soluble TNF-α in the brain contributes to sympathetic excitation in HF.

Sex differences in the central and peripheral manifestations of ischemia-induced heart failure in rats

Sex differences in the presentation, outcome, and responses to treatment of systolic heart failure (HF) have been reported. In the present study, we examined the effect of sex on central neural mechanisms contributing to neurohumoral excitation and its peripheral manifestations in rats with HF. Male and female Sprague-Dawley rats underwent coronary artery ligation (CL) to induce HF. Age-matched rats served as controls. Ischemic zone and left ventricular function were similar 24 h and 4 wk after CL. Female rats with HF had a lower mortality rate and less hemodynamic compromise, pulmonary congestion, and right ventricular remodeling 4 wk after CL. Plasma angiotensin II (ANG II), arginine vasopressin (AVP), and norepinephrine levels were increased in HF rats in both sexes, but AVP and norepinephrine levels increased less in female rats. In the hypothalamic paraventricular nucleus, a key cardiovascular-related nucleus contributing to neurohumoral excitation in HF, mRNA levels for the proinflammatory cytokines tumor necrosis factor-α and interleukin-1β as well as cyclooxygenase-2 and the ANG II type 1a receptor were increased in HF rats of both sexes, but less so in female rats. Angiotensin-converting enzyme 2 protein levels increased in female HF rats but decreased in male HF rats. mRNA levels of AVP were lower in female rats in both control and HF groups compared with the respective male groups. Activation of extracellular signal-regulated protein kinases 1 and 2 increased similarly in both sexes in HF. The results suggest that female HF rats have less central neural excitation and less associated hemodynamic compromise than male HF rats with the same degree of initial ischemic cardiac injury. NEW & NOTEWORTHY Sex differences in the presentation and responses to treatment of heart failure (HF) are widely recognized, but the underlying mechanisms are poorly understood. The present study describes sex differences in the central nervous system mechanisms that drive neurohumoral excitation in ischemia-induced HF. Female rats had a less intense central neurochemical response to HF and experienced less hemodynamic compromise. Sex hormones may contribute to these differences in the central and peripheral adaptations to HF.

E-C coupling structural protein junctophilin-2 encodes a stress-adaptive transcription regulator

Junctophilin-2 (JP2) is a structural protein required for normal excitation-contraction (E-C) coupling. After cardiac stress, JP2 is cleaved by the calcium ion-dependent protease calpain, which disrupts the E-C coupling ultrastructural machinery and drives heart failure progression. We found that stress-induced proteolysis of JP2 liberates an N-terminal fragment (JP2NT) that translocates to the nucleus, binds to genomic DNA, and controls expression of a spectrum of genes in cardiomyocytes. Transgenic overexpression of JP2NT in mice modifies the transcriptional profile, resulting in attenuated pathological remodeling in response to cardiac stress. Conversely, loss of nuclear JP2NT function accelerates stress-induced development of hypertrophy and heart failure in mutant mice. These data reveal a self-protective mechanism in failing cardiomyocytes that transduce mechanical information (E-C uncoupling) into salutary transcriptional reprogramming in the stressed heart.

Glycoprotein-130 Expression Is Associated with Aggressive Bladder Cancer and Is a Potential Therapeutic Target

Predicting bladder cancer progression is important in selecting the optimal treatment for bladder cancer. Because current diagnostic factors regarding progression are lacking, new factors are needed to further stratify the curative potential of bladder cancer. Glycoprotein-130 (GP130), a transmembrane protein, is central to a number of signal transduction pathways involved in tumor aggressiveness, making it an attractive target. We hypothesize that if GP130 is found in an aggressive population of bladder tumors, then blocking GP130 expression may inhibit bladder cancer growth. Herein, we quantitatively show, using 11 patient samples and four bladder cancer cell lines, that GP130 is expressed in the aggressive human bladder tumors and in high-grade bladder cancer cell lines. Moreover, GP130 is significantly correlated with tumor grade, node category, tumor category, and patient outcome. We demonstrated a tumor-specific GP130 effect by blocking GP130 expression in bladder tumor cells, which resulted in decreased cell viability and reduced cell migration. Furthermore, we reduced tumor volume by approximately 70% compared with controls by downregulating GP130 expression using chitosan-functionalized nanoparticles encapsulating GP130 siRNA in an in vivo bladder cancer xenograft mouse model. Our results indicate that GP130 expression is linked to the aggressiveness of bladder tumors, and blocking GP130 has therapeutic potential in controlling tumor growth.

Arginine vasopressin infusion is sufficient to model clinical features of preeclampsia in mice

Copeptin, a marker of arginine vasopressin (AVP) secretion, is elevated throughout human pregnancies complicated by preeclampsia (PE), and AVP infusion throughout gestation is sufficient to induce the major phenotypes of PE in mice. Thus, we hypothesized a role for AVP in the pathogenesis of PE. AVP infusion into pregnant C57BL/6J mice resulted in hypertension, renal glomerular endotheliosis, intrauterine growth restriction, decreased placental growth factor (PGF), altered placental morphology, placental oxidative stress, and placental gene expression consistent with human PE. Interestingly, these changes occurred despite a lack of placental hypoxia or elevations in placental fms-like tyrosine kinase-1 (FLT1). Coinfusion of AVP receptor antagonists and time-restricted infusion of AVP uncovered a mid-gestational role for the AVPR1A receptor in the observed renal pathologies, versus mid- and late-gestational roles for the AVPR2 receptor in the blood pressure and fetal phenotypes. These findings demonstrate that AVP is sufficient to initiate phenotypes of PE in the absence of placental hypoxia, and indicate that AVP may mechanistically (independently, and possibly synergistically with hypoxia) contribute to the development of clinical signs of PE in specific subtypes of human PE. Additionally, they identify divergent and gestational time-specific signaling mechanisms that mediate the development of PE phenotypes in response to AVP.

Targeting Calpain for Heart Failure Therapy: Implications From Multiple Murine Models

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Calpain is hyperactivated in human failing hearts and rodent heart failure models of different etiologies.

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Inhibition of calpain activity with MDL-28170 protects against cardiac dysfunction by preserving JP2 expression and T-tubule ultrastructural integrity in murine models of heart failure.

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Overexpression of JP2 delays the onset of early cardiac sudden death and heart failure, induced by calpain overactivation.

Heart failure remains a major cause of morbidity and mortality in developed countries. There is still a strong need to devise new mechanism-based treatments for heart failure. Numerous studies have suggested the importance of the Ca²⁺-dependent protease calpain in cardiac physiology and pathology. However, no drugs are currently under development or testing in human patients to target calpain for heart failure treatment. Herein the data demonstrate that inhibition of calpain activity protects against deleterious ultrastructural remodeling and cardiac dysfunction in multiple rodent models of heart failure, providing compelling evidence that calpain inhibition is a promising therapeutic strategy for heart failure treatment.

Discovery of an Experimental Model of Unicuspid Aortic Valve

Background

The epithelial growth factor receptor family of tyrosine kinases modulates embryonic formation of semilunar valves. We hypothesized that mice heterozygous for a dominant loss‐of‐function mutation in epithelial growth factor receptor, which are Egfr^Vel/+ mice, would develop anomalous aortic valves, valve dysfunction, and valvular cardiomyopathy.

Methods and Results

Aortic valves from Egfr^Vel/+ mice and control mice were examined by light microscopy at 2.5 to 4 months of age. Additional Egfr^Vel/+ and control mice underwent echocardiography at 2.5, 4.5, 8, and 12 months of age, followed by histologic examination. In young mice, microscopy revealed anatomic anomalies in 79% of Egfr^Vel/+ aortic valves, which resembled human unicuspid aortic valves. Anomalies were not observed in control mice. At 12 months of age, histologic architecture was grossly distorted in Egfr^Vel/+ aortic valves. Echocardiography detected moderate or severe aortic regurgitation, or aortic stenosis was present in 38% of Egfr^Vel/+ mice at 2.5 months of age (N=24) and in 74% by 8 months of age. Left ventricular enlargement, hypertrophy, and reversion to a fetal myocardial gene expression program occurred in Egfr^Vel/+ mice with aortic valve dysfunction, but not in Egfr^Vel/+ mice with near‐normal aortic valve function. Myocardial fibrosis was minimal or absent in all groups.

Conclusions

A new mouse model uniquely recapitulates salient functional, structural, and histologic features of human unicuspid aortic valve disease, which are phenotypically distinct from other forms of congenital aortic valve disease. The new model may be useful for elucidating mechanisms by which congenitally anomalous aortic valves become critically dysfunctional.