Pressure Overload-induced Cardiac Remodeling Research Articles

Blocking CTLA-4 promotes pressure overload-induced heart failure via activating Th17 cells.

Targeting cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) with specific antibody offers long-term benefits for cancer immunotherapy but can cause severe adverse effects in the heart. This study aimed to investigate the role of anti-CTLA-4 antibody in pressure overload-induced cardiac remodeling and dysfunction. Transverse aortic constriction (TAC) was used to induce cardiac hypertrophy and heart failure in mice. Two weeks after the TAC treatment, mice received anti-CTLA-4 antibody injection twice a week at a dose of 10 mg/kg body weight. The administration of anti-CTLA-4 antibody exacerbated TAC-induced decline in cardiac function, intensifying myocardial hypertrophy and fibrosis. Further investigation revealed that anti-CTLA-4 antibody significantly elevated systemic inflammatory factors levels and facilitated the differentiation of T helper 17 (Th17) cells in the peripheral blood of TAC-treated mice. Importantly, anti-CTLA-4 mediated differentiation of Th17 cells and hypertrophic phenotype in TAC mice were dramatically alleviated by the inhibition of interleukin-17A (IL-17A) by an anti-IL-17A antibody. Furthermore, the C-X-C motif chemokine receptor 4 (CXCR4) antagonist AMD3100, also reversed anti-CTLA-4-mediated cardiotoxicity in TAC mice. Overall, these results suggest that the administration of anti-CTLA-4 antibody exacerbates pressure overload-induced heart failure by activating and promoting the differentiation of Th17 cells. Targeting the CXCR4/Th17/IL-17A axis could be a potential therapeutic strategy for mitigating immune checkpoint inhibitors-induced cardiotoxicity.

Disruption of the interaction between caveolae and Piezo1 promotes pressure overload-induced cardiac remodeling

Piezo1 channels are activated by mechanical stress and play a significant role in cardiac hypertrophy and fibrosis. However, the molecular mechanisms underlying Piezo1 activation on the cell membrane following pressure overload remain unclear. Caveolae are known to mitigate mechanical forces and regulate Piezo1 function. Therefore, this study aimed to investigate the interaction between caveolae and Piezo1 in the development of pressure overload-induced cardiac remodeling. We observed reduced colocalization between Piezo1 and Caveolin-3 in hypertrophic cardiomyocytes following abdominal aortic constriction and Angiotensin-II treatment, accompanied by increased Piezo1 function and expression. Furthermore, enhanced Piezo1 function was also noted upon caveolae disruption using methyl-beta-cyclodextrin (mβCD). Thus, our findings suggested that pressure overload led to Piezo1 translocation from caveolae, thereby augmenting its function and expression, which may contribute to cardiac remodeling.

Fenofibrate reduces cardiac remodeling by mitochondrial dynamics preservation in a renovascular model of cardiac hypertrophy

Fenofibrate, a PPAR-α agonist clinically used to lower serum lipid levels, reduces cardiac remodeling and improves cardiac function. However, its mechanism of action is not completely elucidated. In this study we examined the effect of fenofibrate on mitochondria in a rat model of renovascular hypertension, focusing on mediators controlling mitochondrial dynamics and autophagy.Rats with two-kidney one-clip (2K1C) hypertension were treated with fenofibrate 150 mg/kg/day (2K1C-FFB) or vehicle (2K1C-VEH) for 8 weeks. Systolic blood pressure and cardiac functional were in-vivo assessed, while cardiomyocyte size and protein expression of mediators of cardiac hypertrophy and mitochondrial dynamics were ex-vivo examined by histological and Western blot analyses.Fenofibrate treatment counteracted the development of hypertension and the increase of left ventricular mass, relative wall thickness and cross-sectional area of cardiomyocytes. Furthermore, fenofibrate re-balanced the expression Mfn2, Drp1 and Parkin, regulators of fusion, fission, mitophagy respectively. Regarding autophagy, the LC3-II/LC3-I ratio was increased in 2K1C-VEH and 2K1C-FFB, whereas the autophagy was increased only in 2K1C-FFB.In cultured H9C2 cardiomyoblasts, fenofibrate reversed the Ang II-induced mRNA up-regulation of hypertrophy markers Nppa and Myh7, accumulation of reactive oxygen species and depolarization of the mitochondrial membrane exerting protection mediated by up-regulation of the Uncoupling protein 2.Our results indicate that fenofibrate acts directly on cardiomyocytes and counteracts the pressure overload-induced cardiac maladaptive remodeling. This study reveals a so far hidden mechanism involving mitochondrial dynamics in the beneficial effects of fenofibrate, support its repurposing for the treatment of cardiac hypertrophy and provide new potential targets for its pharmacological function.

Proline metabolic reprogramming modulates cardiac remodeling induced by pressure overload in the heart.

Metabolic reprogramming is critical in the onset of pressure overload-induced cardiac remodeling. Our study reveals that proline dehydrogenase (PRODH), the key enzyme in proline metabolism, reprograms cardiomyocyte metabolism to protect against cardiac remodeling. We induced cardiac remodeling using transverse aortic constriction (TAC) in both cardiac-specific PRODH knockout and overexpression mice. Our results indicate that PRODH expression is suppressed after TAC. Cardiac-specific PRODH knockout mice exhibited worsened cardiac dysfunction, while mice with PRODH overexpression demonstrated a protective effect. In addition, we simulated cardiomyocyte hypertrophy in vitro using neonatal rat ventricular myocytes treated with phenylephrine. Through RNA sequencing, metabolomics, and metabolic flux analysis, we elucidated that PRODH overexpression in cardiomyocytes redirects proline catabolism to replenish tricarboxylic acid cycle intermediates, enhance energy production, and restore glutathione redox balance. Our findings suggest PRODH as a modulator of cardiac bioenergetics and redox homeostasis during cardiac remodeling induced by pressure overload. This highlights the potential of PRODH as a therapeutic target for cardiac remodeling.

SIRT3 regulates cardiolipin biosynthesis in pressure overload-induced cardiac remodeling by PPARγ-mediated mechanism.

Cardiac remodeling is the primary pathological feature of chronic heart failure (HF). Exploring the characteristics of cardiac remodeling in the very early stages of HF and identifying targets for intervention are essential for discovering novel mechanisms and therapeutic strategies. Silent mating type information regulation 2 homolog 3 (SIRT3), as a major mitochondrial nicotinamide adenine dinucleotide (NAD)-dependent deacetylase, is required for mitochondrial metabolism. However, whether SIRT3 plays a role in cardiac remodeling by regulating the biosynthesis of mitochondrial cardiolipin (CL) is unknown. In this study, we induced pressure overload in wild-type (WT) and SIRT3 knockout (SIRT3-/-) mice via transverse aortic constriction (TAC). Compared with WT mouse hearts, the hearts of SIRT3-/- mice exhibited more-pronounced cardiac remodeling and fibrosis, greater reactive oxygen species (ROS) production, decreased mitochondrial-membrane potential (ΔΨm), and abnormal mitochondrial morphology after TAC. Furthermore, SIRT3 deletion aggravated TAC-induced decrease in total CL content, which might be associated with the downregulation of the CL synthesis related enzymes cardiolipin synthase 1 (CRLS1) and phospholipid-lysophospholipid transacylase (TAFAZZIN). In our in vitro experiments, SIRT3 overexpression prevented angiotensin II (AngII)- induced aberrant mitochondrial function, CL biosynthesis disorder, and peroxisome proliferator-activated receptor gamma (PPARγ) downregulation in cardiomyocytes; meanwhile, SIRT3 knockdown exacerbated these effects. Moreover, the addition of GW9662, a PPARγ antagonist, partially counteracted the beneficial effects of SIRT3 overexpression. In conclusion, SIRT3 regulated PPARγ-mediated CL biosynthesis, maintained the structure and function of mitochondria, and thereby protected the myocardium against cardiac remodeling.

HINT2 protects against pressure overload-induced cardiac remodelling through mitochondrial pathways.

Histidine triad nucleotide-binding protein 2 (HINT2) is an enzyme found in mitochondria that functions as a nucleotide hydrolase and transferase. Prior studies have demonstrated that HINT2 plays a crucial role in ischemic heart disease, but its importance in cardiac remodelling remains unknown. Therefore, the current study intends to determine the role of HINT2 in cardiac remodelling. HINT2 expression levels were found to be lower in failing hearts and hypertrophy cardiomyocytes. The mice that overexpressed HINT2 exhibited reduced myocyte hypertrophy and cardiac dysfunction in response to stress. In contrast, the deficiency of HINT2 in the heart of mice resulted in a worsening hypertrophic phenotype. Further analysis indicated that upregulated genes were predominantly associated with the oxidative phosphorylation and mitochondrial complex I pathways in HINT2-overexpressed mice after aortic banding (AB) treatment. This suggests that HINT2 increases the expression of NADH dehydrogenase (ubiquinone) flavoprotein (NDUF) genes. In cellular studies, rotenone was used to disrupt mitochondrial complex I, and the protective effect of HINT2 overexpression was nullified. Lastly, we predicted that thyroid hormone receptor beta might regulate HINT2 transcriptional activity. To conclusion, the current study showcased that HINT2 alleviates pressure overload-induced cardiac remodelling by influencing the activity and assembly of mitochondrial complex I. Thus, targeting HINT2 could be a novel therapeutic strategy for reducing cardiac remodelling.

Kielin/chordin-like protein deficiency aggravates pressure overload-induced cardiac dysfunction and remodeling via P53/P21/CCNB1 signaling in mice.

Targeting cardiac remodeling is regarded as a key therapeutic strategy for heart failure. Kielin/chordin-like protein (KCP) is a secretory protein with 18 cysteine-rich domains and associated with kidney and liver fibrosis. However, the relationship between KCP and cardiac remodeling remains unclear. Here, we aimed to investigate the role of KCP in cardiac remodeling induced by pressure overload and explore its potential mechanisms. Left ventricular (LV) KCP expression was measured with real-time quantitative PCR, western blotting, and immunofluorescence staining in pressure overload-induced cardiac remodeling in mice. Cardiac function and remodeling were evaluated in wide-type (WT) mice and KCP knockout (KO) mice by echocardiography, which were further confirmed by histological analysis with hematoxylin and eosin and Masson staining. RNA sequence was performed with LV tissue from WT and KO mice to identify differentially expressed genes and related signaling pathways. Primary cardiac fibroblasts (CFs) were used to validate the regulatory role and potential mechanisms of KCP during fibrosis. KCP was down-regulated in the progression of cardiac remodeling induced by pressure overload, and was mainly expressed in fibroblasts. KCP deficiency significantly aggravated pressure overload-induced cardiac dysfunction and remodeling. RNA sequence revealed that the role of KCP deficiency in cardiac remodeling was associated with cell division, cell cycle, and P53 signaling pathway, while cyclin B1 (CCNB1) was the most significantly up-regulated gene. Further investigation invivo and invitro suggested that KCP deficiency promoted the proliferation of CFs via P53/P21/CCNB1 pathway. Taken together, these results suggested that KCP deficiency aggravates cardiac dysfunction and remodeling induced by pressure overload via P53/P21/CCNB1 signaling in mice.

TIGAR Deficiency Blunts Angiotensin-II-Induced Cardiac Hypertrophy in Mice.

Hypertension is the key contributor to pathological cardiac hypertrophy. Growing evidence indicates that glucose metabolism plays an essential role in cardiac hypertrophy. TP53-induced glycolysis and apoptosis regulator (TIGAR) has been shown to regulate glucose metabolism in pressure overload-induced cardiac remodeling. In the present study, we investigated the role of TIGAR in cardiac remodeling during Angiotensin II (Ang-II)-induced hypertension. Wild-type (WT) and TIGAR knockout (KO) mice were infused with Angiotensin-II (Ang-II, 1 µg/kg/min) via mini-pump for four weeks. The blood pressure was similar between the WT and TIGAR KO mice. The Ang-II infusion resulted in a similar reduction of systolic function in both groups, as evidenced by the comparable decrease in LV ejection fraction and fractional shortening. The Ang-II infusion also increased the isovolumic relaxation time and myocardial performance index to the same extent in WT and TIGAR KO mice, suggesting the development of similar diastolic dysfunction. However, the knockout of TIGAR significantly attenuated hypertension-induced cardiac hypertrophy. This was associated with higher levels of fructose 2,6-bisphosphate, PFK-1, and Glut-4 in the TIGAR KO mice. Our present study suggests that TIGAR is involved in the control of glucose metabolism and glucose transporters by Ang-II and that knockout of TIGAR attenuates the development of maladaptive cardiac hypertrophy.

Retracted: Alleviation of Inflammation and Oxidative Stress in Pressure Overload-Induced Cardiac Remodeling and Heart Failure via IL-6/STAT3 Inhibition by Raloxifene.

[This retracts the article DOI: 10.1155/2021/6699054.].

DEL-1 deficiency aggravates pressure overload-induced heart failure by promoting neutrophil infiltration and neutrophil extracellular traps formation

Recent studies have shown that neutrophils play an important role in the development and progression of heart failure. Developmental endothelial locus-1 (DEL-1) is an anti-inflammatory glycoprotein that has been found to have protective effects in various cardiovascular diseases. However, the role of DEL-1 in chronic heart failure is not well understood. In a mouse model of pressure overload-induced non-ischemic cardiac failure, we found that neutrophil infiltration in the heart increased and DEL-1 levels decreased in the early stages of heart failure. DEL-1 deficiency worsened pressure overload-induced cardiac dysfunction and remodeling in mice. Mechanistically, DEL-1 deficiency promotes neutrophil infiltration and the formation of neutrophil extracellular traps (NETs) through the regulation of P38 signaling. In vitro experiments showed that DEL-1 can inhibit P38 signaling and NETs formation in mouse neutrophils in a MAC-1-dependent manner. Depleting neutrophils, inhibiting NETs formation, and inhibiting P38 signaling all reduced the exacerbation of heart failure caused by DEL-1 deletion. Overall, our findings suggest that DEL-1 deficiency worsens pressure overload-induced heart failure by promoting neutrophil infiltration and NETs formation.

Abstract 14400: Tipifarnib Mediated Reduction of Circulating Exosomes Inhibit Pressure Overload-Induced Cardiac Remodeling and Hypertrophy

Circulating extracellular vesicles, including exosomes, and their content have been implicated in cardiac tissue remodeling during cardiovascular disease progression. However, their role in cardiac hypertrophy and heart failure is very limited. Therefore, we investigated the role of circulating exosomes in cardiac dysfunction and remodeling in a transverse aortic constriction (TAC) model of heart failure using a recently identified exosome biogenesis inhibitor, Tipifarnib. Ten-week-old C57BL6J male mice were randomized into three groups i.e., Sham, TAC and Tipifarnib treated (10 mg/kg) TAC (TAC-Tip). The untreated TAC mice showed a significant increase in circulating exosomes along with gradual development of cardiac hypertrophy accompanied with reduced cardiac functions and increased fibrosis. On the contrary, TAC-Tip mice showed a significant reduction in circulating exosomes and remarkably improved cardiac left ventricular functions, reduced cardiac hypertrophy, fibrosis, and systemic inflammation. Strikingly, when primary mouse cardiac fibroblast cells were treated with exosomes derived from serum of TAC mice, the fibrosis related genes expression was significantly amplified compared to those treated with exosomes from TAC-Tip mice serum. Further, systemic injections of TAC-serum exosomes in normal, uninjured mice for 8 weeks, reduced cardiac function and increased cardiomyocyte hypertrophy. Small RNA sequencing analysis of serum exosomes from TAC and TAC-Tip mice displayed an extensively differential exosomal miRNAs profile. To evaluate the crucial role of miRNA in the circulating exosomes, we selected miR 331-5p based on the most differentially expressed miR and validated its expression in heart tissue and serum exosomes of Sham, TAC and TAC-Tip mice. Functional studies showed miR 331-5p inhibited HOXC8, a critical regulator of fibrosis. Overall, our studies reveal a mechanism by which treatment of Tipifarnib in TAC mice, alters not just the exosome numbers but also circulating exosomes content including miR 331-5p that directly inhibits HOXC8 and reduces fibrosis. Thus, Tipifarnib mediated inhibition of circulating exosomes may serve as a viable strategy to prevent progressive cardiac remodeling to heart failure.

Stachydrine Hydrochloride Regulates the NOX2-ROS-Signaling Axis in Pressure-Overload-Induced Heart Failure.

Our previous studies revealed the protection of stachydrine hydrochloride (STA) against cardiopathological remodeling. One of the underlying mechanisms involves the calcium/calmodulin-dependent protein kinase Ⅱ (CaMKII). However, the way STA influences CaMKII needs to be further investigated. The nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2)-coupled reactive oxygen species (ROS) overproduction putatively induces the oxidative activation of CaMKII, resulting in the occurrence of pathological cardiac remodeling and dysfunction in experimental models of mice. Thus, in this study, we assessed the role of the NOX2-ROS signal axis in STA cardioprotection. The transverse aortic constriction (TAC)-induced heart failure model of mice, the phenylephrine-induced hypertrophic model of neonatal rat primary cardiomyocytes, and the H2O2-induced oxidative stress models of adult mouse primary cardiomyocytes and H9c2 cells were employed. The echocardiography and histological staining were applied to assess the cardiac effect of STA (6 mg/kg/d or 12 mg/kg/d), which was given by gavage. NOX2, ROS, and excitation-contraction (EC) coupling were detected by Western blotting, immunofluorescence, and calcium transient-contraction synchronous recordings. ROS and ROS-dependent cardiac fibrosis were alleviated in STA-treated TAC mice, demonstrating improved left ventricular ejection fraction and hypertrophy. In the heart failure model of mice and the hypertrophic model of cardiomyocytes, STA depressed NOX2 protein expression and activation, as shown by inhibited translocation of its phosphorylation, p67phox and p47phox, from the cytoplasm to the cell membrane. Furthermore, in cardiomyocytes under oxidative stress, STA suppressed NOX2-related cytosolic Ca2+ overload, enhanced cell contractility, and decreased Ca2+-dependent regulatory protein expression, including CaMKⅡ and Ryanodine receptor calcium release channels. Cardioprotection of STA against pressure overload-induced pathological cardiac remodeling correlates with the NOX2-coupled ROS signaling cascade.

Mitophagy deficiency activates stimulator of interferon genes activation and aggravates pathogenetic cardiac remodeling

Stimulator of interferon genes (STING) has recently been found to play a crucial role in cardiac sterile inflammation and dysfunction. The role of stimulator of interferon genes (STING) in cardiac sterile inflammation and dysfunction has been recently discovered. This study aims to examine the involvement of STING in pathological cardiac remodeling and the mechanisms that govern the activation of the STING pathway. To investigate this, transverse aortic constriction (TAC) was performed on STING knockout mice to induce pressure overload-induced cardiac remodeling. Subsequently, cardiac function, remodeling, and inflammation levels were evaluated. The STING pathway was found to be activated in the pressure overload-stressed heart and angiotensin II (Ang II)-stimulated cardiac fibroblasts. Loss of STING expression led to a significant reduction in inflammatory responses, mitochondrial fragmentation, and oxidative stress in the heart, resulting in attenuated cardiac remodeling and dysfunction. Furthermore, the exacerbation of pressure overload-induced STING-mediated inflammation and pathological cardiac remodeling was observed when mitophagy was suppressed through the silencing of Parkin, an E3 ubiquitin ligase. Taken together, these findings indicate that STING represents a newly identified and significant molecule implicated in the process of pathological cardiac remodeling and that mitophagy is an upstream mechanism that regulates STING activation. Targeting STING may therefore provide a novel therapeutic strategy for pathological cardiac remodeling and heart failure.

Lysophosphatidylserine induces necrosis in pressure overloaded male mouse hearts via G protein coupled receptor 34

Heart failure is a leading cause of mortality in developed countries. Cell death is a key player in the development of heart failure. Calcium-independent phospholipase A2β (iPLA2β) produces lipid mediators by catalyzing lipids and induces nuclear shrinkage in caspase-independent cell death. Here, we show that lysophosphatidylserine generated by iPLA2β induces necrotic cardiomyocyte death, as well as contractile dysfunction mediated through its receptor, G protein-coupled receptor 34 (GPR34). Cardiomyocyte-specific iPLA2β-deficient male mice were subjected to pressure overload. While control mice showed left ventricular systolic dysfunction with necrotic cardiomyocyte death, iPLA2β-deficient mice preserved cardiac function. Lipidomic analysis revealed a reduction of 18:0 lysophosphatidylserine in iPLA2β-deficient hearts. Knockdown of Gpr34 attenuated 18:0 lysophosphatidylserine-induced necrosis in neonatal male rat cardiomyocytes, while the ablation of Gpr34 in male mice reduced the development of pressure overload-induced cardiac remodeling. Thus, the iPLA2β—lysophosphatidylserine—GPR34—necrosis signaling axis plays a detrimental role in the heart in response to pressure overload.

A time-series minimally invasive transverse aortic constriction mouse model for pressure overload-induced cardiac remodeling and heart failure.

Transverse aortic constriction (TAC) is a widely-used animal model for pressure overload-induced cardiac hypertrophy and heart failure (HF). The severity of TAC-induced adverse cardiac remodeling is correlated to the degree and duration of aorta constriction. Most studies of TAC are performed with a 27-gauge needle, which is easy to cause a tremendous left ventricular overload and leads to a rapid HF, but it is accompanied by higher mortality attributed to tighter aortic arch constriction. However, a few studies are focusing on the phenotypes of TAC applied with a 25-gauge needle, which produces a mild overload to induce cardiac remodeling and has low post-operation mortality. Furthermore, the specific timeline of HF induced by TAC applied with a 25-gauge needle in C57BL/6 J mice remains unclear. In this study, C57BL/6 J mice were randomly subjected to TAC with a 25-gauge needle or sham surgery. Echocardiography, gross morphology, and histopathology were applied to evaluate time-series phenotypes in the heart after 2, 4, 6, 8, and 12 weeks. The survival rate of mice after TAC was more than 98%. All mice subjected to TAC maintained compensated cardiac remodeling during the first two weeks and began to exhibit heart failure characteristics after 4 weeks upon TAC. At 8 weeks post-TAC, the mice showed severe cardiac dysfunction, hypertrophy, and cardiac fibrosis compared to sham mice. Moreover, the mice raised a severe dilated HF at 12 weeks. This study provides an optimized method of the mild overload TAC-induced cardiac remodeling from the compensatory period to decompensatory HF in C57BL/6 J mice.

Cryptotanshinone Attenuated Pathological Cardiac Remodeling In Vivo and In Vitro Experiments.

Cardiac remodeling has been demonstrated to be the early stage and common pathway for various types of cardiomyopathy, but no specific treatment has been suggested to prevent its development and progress. This study was aimed at assessing whether Cryptotanshinone (CTS) treatment could effectively attenuate cardiac remodeling in vivo and in vitro. Aortic banding (AB) surgery was performed to establish a pressure-overload-induced mouse cardiac remodeling model. Echocardiography and pressure-volume proof were used to examine mouse cardiac function. Hematoxylin and eosin (HE) and Picro-Sirius Red (PSR) staining were used to assess cardiac remodeling in vivo. Mouse hearts were collected to analysis signaling pathway and cardiac remodeling markers, respectively. Furthermore, neonatal rat cardiomyocyte (NRCMs) and cardiac fibroblast (CF) were isolated to investigate the roles and mechanisms of CTS treatment in vitro. CTS administration significantly alleviated pressure-overload-induced mouse cardiac dysfunction, inhibited cardiac hypertrophy, and reduced cardiac fibrosis. Mechanically, CTS treatment significantly inhibited the STAT3 and TGF-β/SMAD3 signaling pathways. In vitro experiments, CTS treatment markedly inhibited AngII-induced cardiomyocyte hypertrophy and TGF-β-induced myofibroblast activation via inhibiting STAT3 phosphorylation and its nuclear translocation. Finally, CTS treatment could not protect against pressure overload-induced mouse cardiac remodeling after adenovirus-associated virus (AAV)9-mediated STAT3 overexpression in mouse heart. CTS treatment might attenuate pathological cardiac remodeling via inhibiting STAT3-dependent pathway.

Macrophage-Specific NLRC5 Protects From Cardiac Remodeling Through Interaction With HSPA8

Macrophages regulate inflammation and the process of tissue repair. Therefore, a better understanding of macrophages in the pathogenesis of heart failure is needed. In patients with hypertrophic cardiomyopathy, NLRC5 was significantly increased in circulating monocytes and cardiac macrophages. Myeloid-specific deletion of NLRC5 aggravated pressure overload-induced pathological cardiac remodeling and inflammation. Mechanistically, NLRC5 interacted with HSPA8 and suppressed NF-κB pathway in macrophages. The absence of NLRC5 in macrophages promoted the secretion of cytokines such as interleukin-6 (IL-6), which affected cardiomyocyte hypertrophy and cardiac fibroblast activation. Tocilizumab, an anti-IL-6 receptor antagonist,may be a novel therapeutic strategy for cardiac remodeling and chronic heart failure.

Functional remodelling of perinuclear mitochondria alters nucleoplasmic Ca2+ signalling in heart failure.

Mitochondrial dysfunction in cardiomyocytes is a hallmark of heart failure development. Although initial studies recognized the importance of different mitochondrial subpopulations, there is a striking lack of direct comparison of intrafibrillar (IF) versus perinuclear (PN) mitochondria during the development of HF. Here, we use multiple approaches to examine the morphology and functional properties of IF versus PN mitochondria in pressure overload-induced cardiac remodelling in mice, and in non-failing and failing human cardiomyocytes. We demonstrate that PN mitochondria from failing cardiomyocytes are more susceptible to depolarization of mitochondrial membrane potential, reactive oxygen species generation and impairment in Ca2+ uptake compared with IF mitochondria at baseline and under physiological stress protocol. We also demonstrate, for the first time to our knowledge, that under normal conditions PN mitochondrial Ca2+ uptake shapes nucleoplasmic Ca2+ transients (CaTs) and limits nucleoplasmic Ca2+ loading. The loss of PN mitochondrial Ca2+ buffering capacity translates into increased nucleoplasmic CaTs and may explain disproportionate rise in nucleoplasmic [Ca2+] in failing cardiomyocytes at increased stimulation frequencies. Therefore, a previously unidentified benefit of restoring the mitochondrial Ca2+ uptake may be normalization of nuclear Ca2+ signalling and alleviation of altered excitation–transcription, which could be an important therapeutic approach to prevent adverse cardiac remodelling.This article is part of the theme issue ‘The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease’.

Inhibitory effect of (pro)renin receptor decoy inhibitor PRO20 on endoplasmic reticulum stress during cardiac remodeling.

Background: Ectopic activation of renin-angiotensin-system contributes to cardiovascular and renal diseases. (Pro)renin receptor (PRR) binds to renin and prorenin, participating in the progression of nephrology. However, whether PRR could be considered as a therapeutic target for cardiac remodeling and heart failure remains unknown. Materials and methods: Transverse aortic constriction (TAC) surgery was performed to establish a mouse model of chronic pressure overload-induced cardiac remodeling. Neonatal rat cardiomyocytes (CMs) and cardiac fibroblasts (CFs) were isolated and stimulated by Angiotensin II (Ang II). PRR decoy inhibitor PRO20 was synthesized and used to evaluate its effect on cardiac remodeling. Results: Soluble PRR and PRR were significantly upregulated in TAC-induced cardiac remodeling and Ang II-treated CMs and CFs. Results of In vivo experiments showed that suppression of PRR by PRO20 significantly retarded cardiac remodeling and heart failure indicated by morphological and echocardiographic analyses. In vitro experiments, PRO20 inhibited CM hypertrophy, and also alleviated CF activation, proliferation and extracellular matrix synthesis. Mechanically, PRO20 enhanced intracellular cAMP levels, but not affected cGMP levels in CMs and CFs. Moreover, treatment of PRO20 in CFs markedly attenuated the production of reactive oxygen species and phosphorylation of IRE1 and PERK, two well-identified markers of endoplasmic reticulum (ER) stress. Accordingly, administration of PRO20 reversed ER stressor thapsigargin-induced CM hypertrophy and CF activation/migration. Conclusion: Taken together, these findings suggest that inhibition of PRR by PRO20 attenuates cardiac remodeling through increasing cAMP levels and reducing ER stress in both CMs and CFs.

Abstract P2022: Tipifarnib Mediated Protection By Reduction Of Circulating Exosomes In Pressure Overloaded Cardiac Hypertrophy

Hypertrophic cardiomyopathy (HCM) in response to pathophysiological stress is one of the leading causes of heart failure. A growing body of evidence emphasizes the crucial role of exosomes and their modulated content in aggravating cardiac damage due to their inherent intercellular cross-talk abilities during cardiac remodeling. However, the role of circulating exosomes in HCM for the trafficking of pathogenic factors and remodeling the cardiac microenvironment is yet unclear. We investigated the effect of systemic exosome inhibition during cardiac dysfunction in a transverse aortic constriction (TAC) model of heart failure using a recently identified exosome biogenesis inhibitor, Tipifarnib initially developed as Farnesyl transferase inhibitor. In this study, 10-week-old C57BL6J male mice were randomized into three groups i.e., Sham, TAC and Tipifarnib treated (10 mg/kg) TAC. The untreated TAC mice gradually developed hypertrophy and had reduced cardiac functions with a significant increase in heart weight/body weight ratio, cardiomyocyte size and upregulation of hypertrophy and fibrosis associated genes expression by 8 weeks. On the contrary, Tipifarnib treated TAC mice showed remarkably improved cardiac left ventricular functions, reduced cardiac hypertrophy and fibrosis. Notably, Nanosight analysis indicated significantly higher serum exosomes concentration in TAC mice which were substantially suppressed with Tipifarnib treatment. The molecular analysis of the heart tissue revealed Tipifarnib treated TAC mice had reduced expression of the proteins involved in exosome biogenesis in comparison to untreated TAC mice. To gain insight into the cargo of these circulating exosomes, we performed the serum cytokine array and serum exosomes miRNA sequencing in untreated and Tipifarnib treated TAC mice. There was a marked reduction in inflammatory cytokines in serum and differentially expressed exosomal miRNAs with Tipifarnib treatment in comparison to the untreated TAC mice. Overall, our studies suggest the promising potential of Tipifarnib that effectively protects against pressure overload-induced cardiac remodeling and dysfunction by suppressing exosome secretion and altering hypertrophic and fibrotic gene expression.