Incomplete structural reverse remodeling from late-stage left ventricular hypertrophy impedes the recovery of diastolic but not systolic dysfunction in rats

Multi-Omic, Histopathologic, and Clinicopathologic Effects of Once-Weekly Oral Rapamycin in a Naturally Occurring Feline Model of Hypertrophic Cardiomyopathy: A Pilot Study

Hypertrophic cardiomyopathy (HCM) remains the single most common cardiomyopathy in cats, with a staggering prevalence as high as 15%. To date, little to no direct therapeutical intervention for HCM exists for veterinary patients. A previous study aimed to evaluate the effects of delayed-release (DR) rapamycin dosing in a client-owned population of subclinical, non-obstructive, HCM-affected cats and reported that the drug was well tolerated and resulted in beneficial LV remodeling. However, the precise effects of rapamycin in the hypertrophied myocardium remain unknown. Using a feline research colony with naturally occurring hereditary HCM (n = 9), we embarked on the first-ever pilot study to examine the tissue-, urine-, and plasma-level proteomic and tissue-level transcriptomic effects of an intermittent low dose (0.15 mg/kg) and high dose (0.30 mg/kg) of DR oral rapamycin once weekly. Rapamycin remained safe and well tolerated in cats receiving both doses for eight weeks. Following repeated weekly dosing, transcriptomic differences between the low- and high-dose groups support dose-responsive suppressive effects on myocardial hypertrophy and stimulatory effects on autophagy. Differences in the myocardial proteome between treated and control cats suggest potential anti-coagulant/-thrombotic, cellular remodeling, and metabolic effects of the drug. The results of this study closely recapitulate what is observed in the human literature, and the use of rapamycin in the clinical setting as the first therapeutic agent with disease-modifying effects on HCM remains promising. The results of this study establish the need for future validation efforts that investigate the fine-scale relationship between rapamycin treatment and the most compelling gene expression and protein abundance differences reported here.

Pressure overload-induced systolic heart failure is associated with characteristic myocardial microRNA expression signature and post-transcriptional gene regulation in male rats

Although systolic function characteristically shows gradual impairment in pressure overload (PO)-evoked left ventricular (LV) hypertrophy (LVH), rapid progression to congestive heart failure (HF) occurs in distinct cases. The molecular mechanisms for the differences in maladaptation are unknown. Here, we examined microRNA (miRNA) expression and miRNA-driven posttranscriptional gene regulation in the two forms of PO-induced LVH (with/without systolic HF). PO was induced by aortic banding (AB) in male Sprague-Dawley rats. Sham-operated animals were controls. The majority of AB animals demonstrated concentric LVH and slightly decreased systolic function (termed as ABLVH). In contrast, in some AB rats severely reduced ejection fraction, LV dilatation and increased lung weight-to-tibial length ratio was noted (referred to as ABHF). Global LV miRNA sequencing revealed fifty differentially regulated miRNAs in ABHF compared to ABLVH. Network theoretical miRNA-target analysis predicted more than three thousand genes with miRNA-driven dysregulation between the two groups. Seventeen genes with high node strength value were selected for target validation, of which five (Fmr1, Zfpm2, Wasl, Ets1, Atg16l1) showed decreased mRNA expression in ABHF by PCR. PO-evoked systolic HF is associated with unique miRNA alterations, which negatively regulate the mRNA expression of Fmr1, Zfmp2, Wasl, Ets1 and Atg16l1.

Sex similarities and differences in the reverse and anti-remodeling effect of pressure unloading therapy in a rat model of aortic banding and debanding

BACKGROUND

Investigating the effect of sex on pressure unloading therapy in a clinical scenario is limited by several non-standardized factors. Hence, we sought to study sex-related similarities and differences under laboratory conditions.

METHODS

Pressure overload was induced in male and female rats by aortic banding (AB) for 6 and 12 weeks. Age-matched sham operated animals served as controls. Pressure unloading was performed by aortic debanding at week 6. Different aspects of myocardial remodeling were characterized by echocardiography, pressure-volume analysis, histology, qRT-PCR and explorative proteomics.

RESULTS

Hypertrophy, increased fetal gene expression, interstitial fibrosis, and prolonged active relaxation were noted in the AB groups at week 6 in both sexes. However, decompensation of systolic function and further deterioration of diastolic function only occurred in male AB rats at week 12. AB induced similar proteomic alterations in both sexes at week 6, while characteristic differences were found at week 12. After debanding, regression of hypertrophy and recovery of diastolic function took place to a similar extent in both sexes. Nevertheless, fibrosis, transcription of β-to-α myosin-heavy chain ratio, and myocardial proteomic alterations were reduced to a greater degree in females compared to males. Debanding exposed anti-remodeling properties in both sexes, and prevented the functional decline in males.

CONCLUSIONS

Female sex is associated with greater reversibility of fibrosis, fetal gene expression, and proteomic alterations. Nevertheless, pressure unloading exposes a more pronounced anti-remodeling effect on the functional level in males, which is attributed to the more progressive functional deterioration in AB animals.

Effect of Danqi Buxin Decoction on Chronic Function Indexes and Life Quality in Patients with Chronic Heart Failure of Yang Deficiency Type

Objective

The purpose was to explore the clinical effect of Danqi Buxin decoction on chronic heart failure (CHF) with yang deficiency and its effect on cardiac function and life quality of patients.

Methods

106 CHF patients with yang deficiency treated in Jinan Municipal Hospital of Traditional Chinese Medicine from February 2019 to February 2020 were selected as the research objects and divided into the treatment group and reference group according to the odd and even admission numbers, with 53 cases in each group. The reference group was treated with routine antiheart failure drugs, while the treatment group was additionally treated with Danqi Buxin decoction to compare the clinical effect and cardiac function changes between the two groups.

Results

The clinical effective rate in the treatment group was significantly higher than that in the reference group (P < 0.05). The TCM symptom scores at T1, T2, and T3 in the treatment group were significantly higher than those in the reference group (P < 0.05). After treatment, the LVEDV levels in both groups were significantly higher than those before treatment, while the BNP levels were significantly lower than those before treatment (P < 0.001). The LVEDV level in the treatment group after treatment was higher than that in the reference group, while the BNP level in the treatment group was significantly lower than that in the reference group (P < 0.001). The life quality scores in the treatment group after treatment were significantly higher than those in the reference group (P < 0.05).

Conclusion

Danqi Buxin decoction on the basis of conventional drugs can significantly improve the cardiac function and life quality of CHF patients with yang deficiency type. Its further research is helpful to establish a good treatment plan for CHF patients.

Myocardial work index: a marker of left ventricular contractility in pressure- or volume overload-induced heart failure

Aims

While global longitudinal strain (GLS) is considered to be a sensitive marker of left ventricular (LV) function, it is significantly influenced by loading conditions. We hypothesized that global myocardial work index (GMWI), a novel marker of LV function, may show better correlation with load‐independent markers of LV contractility in rat models of pressure‐induced or volume overload‐induced heart failure.

Methods and results

Male Wistar rats underwent either transverse aortic constriction (TAC; n = 12) or aortocaval fistula creation (ACF; n = 12), inducing LV pressure or volume overload, respectively. Sham procedures were performed to establish control groups (n = 12/12). Echocardiographic loops were obtained to determine GLS and GMWI. Pressure‐volume analysis with transient occlusion of the inferior caval vein was carried out to calculate preload recruitable stroke work (PRSW), a load‐independent ‘gold‐standard’ parameter of LV contractility. Myocardial samples were collected to assess interstitial and perivascular fibrosis area and also myocardial atrial‐type natriuretic peptide (ANP) and brain‐type natriuretic peptide (BNP) relative mRNA expression. Compared with controls, GLS was substantially lower in the TAC group (−7.0 ± 2.8 vs. −14.5 ± 2.5%; P < 0.001) and was only mildly reduced in the ACF group (−13.2 ± 2.4 vs. −15.4 ± 2.0%, P < 0.05). In contrast with these findings, PRSW and GMWI were comparable with sham in TAC (110 ± 26 vs. 116 ± 68 mmHg; 1687 ± 275 mmHg% vs. 1537 ± 662 mmHg%; both P = NS), while it was found to be significantly reduced in ACF (58 ± 14 vs. 111 ± 40 mmHg; 1328 ± 411 vs. 1934 ± 308 mmHg%, both P < 0.01). In the pooled population, GMWI (r = 0.70; P < 0.001) but not GLS (r = −0.23; P = 0.12) showed a strong correlation with PRSW. GLS correlated with interstitial (r = 0.61; P < 0.001) and perivascular fibrosis area (r = 0.54; P < 0.001), and also with myocardial ANP (r = 0.85; P < 0.001) and BNP relative mRNA expression (r = 0.75; P < 0.001), while GMWI demonstrated no or only marginal correlation with these parameters.

Conclusions

Being significantly influenced by loading conditions, GLS may not be a reliable marker of LV contractility in heart failure induced by pressure or volume overload. GMWI better reflects contractility in haemodynamic overload states, making it a more robust marker of systolic function, while GLS should be considered as an integrative marker, incorporating systolic function, haemodynamic loading state, and adverse tissue remodelling of the LV.

Protection of Sacubitril/Valsartan against Pathological Cardiac Remodeling by Inhibiting the NLRP3 Inflammasome after Relief of Pressure Overload in Mice

BACKGROUND/AIMS

The persistent existence of pathological cardiac remodeling, resulting from aortic stenosis, is related to poor clinical prognosis after successful transcatheter aortic valve replacement (TAVR). Sacubitril/valsartan (Sac/Val), comprising an angiotensin receptor blocker and a neprilysin inhibitor, has been demonstrated to have a beneficial effect against pathological cardiac remodeling, including cardiac fibrosis and inflammation in heart failure. The aim of this study was to determine whether Sac/Val exerts a cardioprotective effect after pressure unloading in mice.

METHODS AND RESULTS

Male C57BL/6 J mice were subjected to debanding (DB) surgery after 8 weeks (wk) of aortic banding (AB). Cardiac function was assessed by echocardiography, which indicated a protective effect of Sac/Val after DB. After treatment with Sac/Val post DB, decreased heart weight and myocardial cell size were observed in mouse hearts. In addition, histological analysis, immunofluorescence, and western blot results showed that Sac/Val attenuated cardiac fibrosis and inflammation after DB. Finally, our data indicated that Sac/Val treatment could significantly suppress NF-κB signaling and NLRP3 inflammasome activation in mice after relief of pressure overload.

CONCLUSION

Sac/Val exerted its beneficial effects to prevent maladaptive cardiac fibrosis and dysfunction in mice following pressure unloading, which was at least partly due to the inhibition of NLRP3 inflammasome activation.