Protective Effects of Sacubitril/Valsartan on Cardiac Fibrosis and Function in Rats With Experimental Myocardial Infarction Involves Inhibition of Collagen Synthesis by Myocardial Fibroblasts Through Downregulating TGF-β1/Smads Pathway

LCZ696, an angiotensin receptor-neprilysin inhibitor, ameliorates epithelial-mesenchymal transition of peritoneal mesothelial cells and M2 macrophage polarization

AIMS

To investigate the effects and mechanisms of LCZ696, an angiotensin receptor-neprilysin inhibitor (ARNI), on epithelial-mesenchymal transition (EMT) of peritoneal mesothelial cells and on macrophage M2 polarization.

METHODS

We examined the effects of LCZ696 in a 4.25% high glucose peritoneal dialysis fluid (PDF)-induced peritoneal fibrosis (PF) mouse model, and explored the mechanisms of LCZ696 on human peritoneal mesothelial cells (HPMCs) stimulated by TGF-β1 (5 ng/mL) and on Raw264.7 cells stimulated by IL-4 (10 ng/mL). To further elucidate the mechanism, we treated HPMCs with the conditioned medium of Raw264.7 cells.

RESULTS

LCZ696 effectively improved PF and inhibited the process of EMT in PDF mice. In vitro, LCZ696 also significantly alleviated the EMT of TGF-β1 induced HPMCs, although there was no statistically significant difference when compared to the Valsartan treatment group. Moreover, LCZ696 ameliorates the increased expression of Snail and Slug, two nuclear transcription factors that drive the EMT. Mechanistically, TGF-β1 increased the expression of TGFβRI, p-Smad3, p-PDGFRβ and p-EGFR, while treatment with LCZ696 abrogated the activation of TGF-β/Smad3, PDGFRβ and EGFR signaling pathways. Additionally, exposure of Raw264.7 to IL-4 results in increasing expression of Arginase-1, CD163 and p-STAT6. Treatment with LCZ696 inhibited IL-4-elicited M2 macrophage polarization by inactivating the STAT6 signaling pathway. Furthermore, we observed that LCZ696 inhibits EMT by blocking TGF-β1 secretion from M2 macrophages.

CONCLUSION

Our study demonstrated that LCZ696 improves PF and ameliorates TGF-β1-induced EMT of HPMCs by blocking TGF-β/Smad3, PDGFRβ and EGFR pathways. Meanwhile, LCZ696 also inhibits M2 macrophage polarization by regulating STAT6 pathway.

Antiarrhythmic and Anti-Inflammatory Effects of Sacubitril/Valsartan on Post-Myocardial Infarction Scar

BACKGROUND

Sacubitril/valsartan (Sac/Val) is superior to angiotensin-converting enzyme inhibitors in reducing the risk of heart failure hospitalization and cardiovascular death, but its mechanistic data on myocardial scar after myocardial infarction (MI) are lacking. The objective of this work was to assess the effects of Sac/Val on inflammation, fibrosis, electrophysiological properties, and ventricular tachycardia inducibility in post-MI scar remodeling in swine.

METHODS

After MI, 22 pigs were randomized to receive β-blocker (BB; control, n=8) or BB+Sac/Val (Sac/Val, n=9). The systemic immune response was monitored. Cardiac magnetic resonance data were acquired at 2-day and 29-day post MI to assess ventricular remodeling. Programmed electrical stimulation and high-density mapping were performed at 30-day post MI to assess ventricular tachycardia inducibility. Myocardial samples were collected for histological analysis.

RESULTS

Compared with BB, BB+Sac/Val reduced acute circulating leukocytes (P=0.009) and interleukin-12 levels (P=0.024) at 2-day post MI, decreased C-C chemokine receptor type 2 expression in monocytes (P=0.047) at 15-day post MI, and reduced scar mass (P=0.046) and border zone mass (P=0.043). It also lowered the number and mass of border zone corridors (P=0.009 and P=0.026, respectively), scar collagen I content (P=0.049), and collagen I/III ratio (P=0.040). Sac/Val reduced ventricular tachycardia inducibility (P=0.034) and the number of deceleration zones (P=0.016).

CONCLUSIONS

After MI, compared with BB, BB+Sac/Val was associated with reduced acute systemic inflammatory markers, reduced total scar and border zone mass on late gadolinium-enhanced magnetic resonance imaging, and lower ventricular tachycardia inducibility.

Sacubitril/valsartan cardioprotective effect against cisplatin-induced cardiotoxicity via modulation of VEGF/eNOS and TLR4/TNFα/IL6 signalling pathways

OBJECTIVES

Drug-induced cardiac injury is a potentially preventable cause of heart failure. Cisplatin (CIS) is a widely used chemotherapeutic agent complicated with cardiotoxicity that limits its clinical application so we aimed to evaluate the suspected cardioprotective effect of sacubitril/valsartan (Sac/Val) against CIS cardiotoxic injury.

METHODS

Forty male rats of Wistar albino species were divided into four groups. group I received the vehicle; group II was given the vehicle plus CIS (10 mg/kg) single i.p. on fifth day; group III was given Sac/Val (30 mg/kg/d) orally for 7 days plus CIS (10 mg/kg) single i.p. on fif5th day; group IV was given the same as group III plus nitro-ω-L-arginine (L-NNA) (25 mg/kg/d) orally for 7 days.

KEY FINDINGS

CIS-induced cardiotoxicity and L-NNA co-administered group showed significant increases in cardiac enzymes, toxic histopathological features, elevated heart weights, angiotensin II (Ang II), neprilysin, malondialdehyde (MDA), inflammatory mediators, blood pressure (BP) and caspase 3 expressions, but there are significant decreases in the antioxidant parameters, vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS). However, the co-administration of Sac/Val could ameliorate these changes of CIS.

CONCLUSION

Sac/Val has an important cardioprotective effect against CIS cardiotoxicity with the involvement of eNOS.

The history and mystery of sacubitril/valsartan: From clinical trial to the real world

Heart failure is a serious threat to human health, with morbidity and mortality rates increasing despite the existence of multiple treatment options. Therefore, it is necessary to identify new therapeutic targets for this disease. Sacubitril/valsartan is a supramolecular sodium salt complex of the enkephalinase inhibitor prodrug sacubitril and the angiotensin receptor blocker valsartan. Its combined action increases endogenous natriuretic peptides while inhibiting the renin-angiotensin-aldosterone system and exerting cardioprotective effects. Clinical evidence suggests that sacubitril/valsartan is superior to conventional renin-angiotensin-aldosterone inhibitor therapy for patients with reduced ejection fraction heart failure who can tolerate angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers. The therapy reduces the risk of heart failure hospitalization, cardiovascular mortality, and all-cause mortality and has a better safety and tolerability record. This review describes the potential pathophysiological mechanisms of cardiomyocyte injury amelioration by sacubitril/valsartan. We explore the protective effects of sacubitril/valsartan and outline the therapeutic value in patients with heart failure by summarizing the results of recent large clinical trials. Furthermore, a preliminary outlook shows that sacubitril/valsartan may be effective at treating other diseases, and provides some exploratory observations that lay the foundation for future studies on this drug.

The protective effect of zinc, selenium, and chromium on myocardial fibrosis in the offspring of rats with gestational diabetes mellitus

The offspring of gestational diabetes mellitus (GDM) mothers are considered to be at the risk of cardiovascular diseases due to intrauterine hyperglycemia exposure. Our previous study showed that zinc, selenium, and chromium dramatically alleviated glucose intolerance in GDM rats and their offspring (P < 0.05). However, the effects of these elements on the damage of the cardiac myocytes of GDM offspring and the underlying mechanisms have not been demonstrated. Here, we investigated the beneficial effects of zinc (10 mg per kg bw), selenium (20 μg per kg bw), and chromium (20 μg per kg bw) supplementation on myocardial fibrosis in the offspring of GDM rats induced by a high-fat and sucrose (HFS) diet. The results showed that maternal GDM induced glucose intolerance, oxidative stress, cardiac inflammation and myocardial fibrosis in offspring rats during different ages (3 days, 3 weeks, and adulthood), which were ameliorated by zinc, selenium and chromium supplementation (P < 0.05). The activity of cardiac damage markers such as creatine kinase-myocardial band isoenzyme (CK-MB), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) decreased by 40-60% in element-supplemented offspring compared to that in non-supplemented offspring of GDM dams (P < 0.05). Moreover, maternal GDM-induced expression of fibrosis-related proteins and the transforming growth factor-beta 1 (TGF-β1)/small mothers against decapentaplegic homolog 3 (Smad3) signaling pathway in the heart tissue of offspring was down-regulated by zinc, selenium, and chromium supplementation (P < 0.05). In conclusion, zinc, selenium, and chromium may play a protective role in maternal GDM-induced myocardial fibrosis in offspring from birth to adulthood by inactivating the TGF-β1/Smad3 pathway.

Secukinumab and Black Garlic Downregulate OPG/RANK/RANKL Axis and Devitalize Myocardial Interstitial Fibrosis Induced by Sunitinib in Experimental Rats

Sunitinib has been associated with several cardiotoxic effects such as cardiac fibrosis. The present study was designed to explore the role of interleukin (IL)-17 in sunitinib-induced myocardial fibrosis (MF) in rats and whether its neutralization and/or administration of black garlic (BG), a form of fermented raw garlic (Allium sativum L.), could extenuate this adverse effect. Male Wistar albino rats received sunitinib (25 mg/kg three times a week, orally) and were co-treated with secukinumab (3 mg/kg, subcutaneously, three times total) and/or BG (300 mg/kg/day, orally) for four weeks. Administration of sunitinib induced significant increase in cardiac index, cardiac inflammatory markers, and cardiac dysfunction that were ameliorated by both secukinumab and BG, and to a preferable extent, with the combined treatment. Histological examination revealed disruption in the myocardial architecture and interstitial fibrosis in cardiac sections of the sunitinib group, which were reversed by both secukinumab and BG treatments. Both drugs and their co-administration restored normal cardiac functions, downregulated cardiac inflammatory cytokines, mainly IL-17 and NF-κB, along with increasing the MMP1/TIMP1 ratio. Additionally, they attenuated sunitinib-induced upregulation of the OPG/RANK/RANKL axis. These findings highlight another new mechanism through which sunitinib can induce interstitial MF. The current results propose that neutralizing IL-17 by secukinumab and/or supplementation with BG can be a promising therapeutic approach for ameliorating sunitinib-induced MF.

Signaling Pathways and Potential Therapeutic Strategies in Cardiac Fibrosis

Cardiac fibrosis constitutes irreversible necrosis of the heart muscle as a consequence of different acute (myocardial infarction) or chronic (diabetes, hypertension, …) diseases but also due to genetic alterations or aging. Currently, there is no curative treatment that is able to prevent or attenuate this phenomenon that leads to progressive cardiac dysfunction and life-threatening outcomes. This review summarizes the different targets identified and the new strategies proposed to fight cardiac fibrosis. Future directions, including the use of exosomes or nanoparticles, will also be discussed.

The impact of Sacubitril/Valsartan on cardiac fibrosis early after myocardial infarction in hypertensive rats

BACKGROUND

Sacubitril/Valsartan, a dual inhibitor of the neprilysin and angiotensin receptor, exerts cardioprotective effects in heart failure. Little is known on the impact of Sacubitril/Valsartan in hypertensive patients early post myocardial infarction.

METHODS

Spontaneously hypertensive rats (SHR) were pretreated by daily angiotensin receptor blocker (ARB; 30 mg/kg intraperitoneally), Sacubitril/Valsartan (ARNI; 60 mg/kg intraperitoneally) or the same dosage of physiological saline for 1 week. Then each group underwent myocardial infarction induction and received the same treatment for another week. The blood pressure and cardiac function were evaluated prior to sacrifice. We performed histological and molecular evaluation of fibrosis in vivo and in vitro.

RESULTS

The blood pressure was comparable between three groups both 1 week prior to and post myocardial infarction. ARNI and ARB restore the decreased ejection fraction (57.3 ± 7.6 vs. 42.9 ± 5.2%, P < 0.05; 54.3 ± 6.9 vs. 42.9 ± 5.2%, P < 0.01, respectively) and fractional shortening (31.6 ± 5.4 vs. 22.1 ± 3.1%, P < 0.05; 29.4 ± 4.5 vs. 22.1 ± 3.1%, P < 0.05, respectively) post myocardial infarction. The infarct size and collagen deposition were also significantly mitigated in ARNI and ARB groups. In addition, ARNI and ARB treatment reduced the expression of cardiac remodeling-related factors, such as Bnp, α-SMA, Vimentin, and Col1a1 (all P < 0.05 vs. MI group). Finally, ARNI and ARB decreased the expression of α-SMA in cardiac fibroblasts treated with Ang II.

CONCLUSION

In conclusion, pretreatment with ARNI maintained cardiac function and reduced myocardial fibrosis in myocardial infarction, probably prior to any anti-hypertensive effect.

Molecular mechanisms of sacubitril/valsartan in cardiac remodeling

Cardiovascular diseases have become a major clinical burden globally. Heart failure is one of the diseases that commonly emanates from progressive uncontrolled hypertension. This gives rise to the need for a new treatment for the disease. Sacubitril/valsartan is a new drug combination that has been approved for patients with heart failure. This review aims to detail the mechanism of action for sacubitril/valsartan in cardiac remodeling, a cellular and molecular process that occurs during the development of heart failure. Accumulating evidence has unveiled the cardioprotective effects of sacubitril/valsartan on cellular and molecular modulation in cardiac remodeling, with recent large-scale randomized clinical trials confirming its supremacy over other traditional heart failure treatments. However, its molecular mechanism of action in cardiac remodeling remains obscure. Therefore, comprehending the molecular mechanism of action of sacubitril/valsartan could help future research to study the drug's potential therapy to reduce the severity of heart failure.

Sacubitril/valsartan in Heart Failure and Beyond-From Molecular Mechanisms to Clinical Relevance

As the ultimate pathophysiological event, heart failure (HF) may arise from various cardiovascular (CV) conditions, including sustained pressure/volume overload of the left ventricle, myocardial infarction or ischemia, and cardiomyopathies. Sacubitril/valsartan (S/V; formerly termed as LCZ696), a first-in-class angiotensin receptor/neprilysin inhibitor, brought a significant shift in the management of HF with reduced ejection fraction by modulating both renin-angiotensin-aldosterone system (angiotensin II type I receptor blockage by valsartan) and natriuretic peptide system (neprilysin inhibition by sacubitril) pathways. Besides, the efficacy of S/V has been also investigated in the setting of other CV pathologies which are during their pathophysiological course and progression deeply interrelated with HF. However, its mechanism of action is not entirely clarified, suggesting other off-target benefits contributing to its cardioprotection. In this review article our goal was to highlight up-to-date clinical and experimental evidence on S/V cardioprotective effects, as well as most discussed molecular mechanisms achieved by this dual-acting compound. Although S/V was extensively investigated in HF patients, additional large studies are needed to elucidate its effects in the setting of other CV conditions. Furthermore, with its antiinflamatory potential, this agent should be investigated in animal models of inflammatory heart diseases, such as myocarditis, while it may possibly improve cardiac dysfunction as well as inflammatory response in this pathophysiological setting. Also, discovering other signalling pathways affected by S/V should be of particular interest for basic researches, while it can provide additional understanding of its cardioprotective mechanisms.