Sacubitril/valsartan reduces endoplasmic reticulum stress in a rat model of doxorubicin-induced cardiotoxicity

Mechanisms of doxorubicin-induced cardiac inflammation and fibrosis; therapeutic targets and approaches

Doxorubicin plays a pivotal role in the treatment of various malignancies. Despite its efficacy, the cardiotoxicity associated with doxorubicin limits its clinical utility. The cardiotoxic nature of doxorubicin is attributed to several mechanisms, including its interference with mitochondrial function, the generation of reactive oxygen species (ROS), and the subsequent damage to cardiomyocyte DNA, proteins, and lipids. Furthermore, doxorubicin disrupts the homeostasis of cardiac-specific transcription factors and signaling pathways, exacerbating cardiac dysfunction. Oxidative stress, cell death, and other severe changes, such as mitochondrial dysfunction, activation of pro-oxidant enzymes, the renin-angiotensin system (RAS), endoplasmic reticulum (ER) stress, and infiltration of immune cells in the heart after treatment with doxorubicin, may cause inflammatory and fibrotic responses. Fibrosis and inflammation can lead to a range of disorders in the heart, resulting in potential cardiac dysfunction and disease. Various adjuvants have shown potential in preclinical studies to mitigate these challenges associated with cardiac inflammation and fibrosis. Antioxidants, plant-based products, specific inhibitors, and cardioprotective drugs may be recommended to alleviate cardiotoxicity. This review explores the complex mechanisms of doxorubicin-induced heart inflammation and fibrosis, identifies possible cellular and molecular targets, and investigates potential substances that could help reduce these harmful effects.

Repurposing Aprepitant: Can it protect against doxorubicin-induced Chemobrain beyond its antiemetic role?

The substance P (SP) and neurokinin-1 receptor (NK-1R) axis is crucial in numerous pathological processes, including inflammation, stress responses, pain perception, and vomiting. Consequently, aprepitant, an NK-1R blocker, is used as an antiemetic in chemotherapy, including the use of doxorubicin (DOX), but whether aprepitant can also assuage DOX-mediated chemobrain remains to be unveiled. Here, we scrutinized the potential neuroprotective effect and underlying mechanisms of aprepitant using DOX-induced chemobrain model, where rats were allocated into 4 groups (control, aprepitant, DOX, and DOX+ aprepitant). Cognitive deficits were assessed through behavioral tests and hippocampal structural alterations were determined by H&E and toluidine blue staining. Biochemical measurements were performed using ELISA, real-time quantitative PCR, western blotting, and immunohistochemical methods. Aprepitant improved cognitive responses, and hippocampal morphology, enhancing the presence of intact neurons. At the molecular tier, aprepitant significantly reduced hippocampal contents of SP and the inflammatory markers NF-κB and IL-1β. Additionally, it signified its antioxidant and antiapoptotic capacities by downregulating cleaved caspase-3 protein expression and curbing the content of malondialdehyde but boosted those of glutathione and Bcl-2. Aprepitant also downregulated the expression of miR-146a and turned off the endoplasmic reticulum (ER) stress cascade PERK/eIF-2α/ATF-4/CHOP. To recapitulate, aprepitant demonstrates a neuroprotective effect against DOX-mediated chemobrain by alleviating inflammatory, oxidative, and apoptotic responses, partly by reducing SP, ER stress, and miR-146a. These findings not only underscore the potential of aprepitant as a neuroprotective agent but also offer new understanding of the mechanisms behind chemobrain, leading to better therapeutic strategies for cancer patients.

Sacubitril/valsartan attenuated myocardial inflammation, fibrosis, apoptosis and promoted autophagy in doxorubicin-induced cardiotoxicity mice via regulating the AMPKα-mTORC1 signaling pathway

This study aimed to investigate the potential cardioprotective effects of sacubitril/valsartan (Sac/Val) in mice with doxorubicin (DOX)-induced cardiomyopathy, a common manifestation of cancer therapy-related cardiac dysfunction (CTRCD) associated with DOX. A total of thirty-two mice were equally classified into 4 groups: control group, DOX (total 24 mg/kg), Sac/Val (80 mg/kg), and Sac/Val + DOX (Sac/Val was given from seven days before doxorubicin administration). Neonatal rat ventricular myocytes was exposed to 5 µM of DOX for 6 h in vitro to mimic the in vivo conditions. A variety of techniques were used to investigate cardiac inflammation, fibrosis, apoptosis, and autophagy, including western blot, real-time quantitative PCR (RT-qPCR), immunohistochemistry, and fluorescence. Mice with DOX-induced cardiotoxicity displayed impaired systolic and diastolic function, characterized by elevated levels of cardiac inflammation, fibrosis, cardiomyocyte hypertrophy, apoptosis, and autophagy inhibition in the heart. Treatment with Sac/Val partially reversed these effects. In comparison to the control group, the protein expression of NLRP3, caspase-1, collagen I, Bax, cleaved caspase-3, and P62 were significantly increased, while the protein expression of Bcl-2 and LC3-II were significantly decreased in the myocardial tissues of the Dox-induced cardiomyopathy group. The administration of Sac/Val demonstrated the potential to partially reverse alterations in protein expression within the myocardium of mice with DOX-induced cardiotoxicity by modulating the AMPKα-mTORC1 signaling pathway and suppressing oxidative stress. Additionally, Sac/Val treatment may mitigate Dox-induced apoptosis and inhibition of autophagy in primary cardiomyocytes. Sac/Val seems to be cardioprotective against DOX-induced cardiotoxicity in the pre-treatment mice model. These findings could be attributed to the anti-inflammatory, antioxidant, anti-apoptotic, and de-autophagy effects of Sac/Val through regulation of the AMPKα-mTORC1 signaling pathway.

Sacubitril/valsartan alleviates sepsis-induced myocardial injury in rats via dual angiotensin receptor-neprilysin inhibition and modulation of inflammasome/caspase 1/IL1β pathway

Sepsis is a life-threatening situation that ultimately affects cardiac function, leading to cardiomyopathy and myocardial injury as a result of uncontrolled response to infection.Till now, there is limited effective treatment to rescue those cases. Thus, novel therapeutic strategies should be identified to achieve better outcomes for septic patients. For the first time, we aimed to evaluate the effect of sacubitril/valsartan (Sac/Val) on sepsis-induced cardiac injury. Wistar male adult albino rats were randomly divided into four groups; Group I received the vehicle; Group II was given the vehicle plus 1 ml saline containing viable Escherichia coli (E. coli) (2.1 × 109 cfu) by intraperitoneal (i.p.) injection on the 1st and 2nd days; Group III received i.p. injection as group II plus oral administration of Sac/Val (30 mg/kg/day) and Nitro- ω-L-arginine (L-NNA) (25 mg/kg/day) for 7 days. Group IV was administered i.p. injection as group II plus oral administration of Sac/Val (30 mg/kg/day) for 7 days. Our data (n = 10) revealed successful induction of sepsis as it showed a significant increase in the measured cardiac enzymes, malondialdehyde (MDA), angiotensin II (Ang II), neprilysin, inflammasome, caspase 1, interleukin (IL)1β, and caspase 3 with cardiac histopathological changes, but there was a significant decrease in the antioxidants and blood pressure (BP). Co-administration of Sac/Val could obviously improve these changes. Interestingly, L-NNA given group showed a decrease in the cardioprotective effect of Sac/Val. Sac/Val could ameliorate sepsis induced cardiac damage via inhibition of Ang II and neprilysin with anti-inflammatory, anti-oxidant and anti-apoptotic properties.

Potential role of endoplasmic reticulum stress in doxorubicin-induced cardiotoxicity-an update

As a chemotherapy agent, doxorubicin is used to combat cancer. However, cardiotoxicity has limited its use. The existing strategies fail to eliminate doxorubicin-induced cardiotoxicity, and an in-depth exploration of its pathogenesis is in urgent need to address the issue. Endoplasmic reticulum stress (ERS) occurs when Endoplasmic Reticulum (ER) dysfunction results in the accumulation of unfolded or misfolded proteins. Adaptive ERS helps regulate protein synthesis to maintain cellular homeostasis, while prolonged ERS stimulation may induce cell apoptosis, leading to dysfunction and damage to tissue and organs. Numerous studies on doxorubicin-induced cardiotoxicity strongly link excessive activation of the ERS to mechanisms including oxidative stress, calcium imbalance, autophagy, ubiquitination, and apoptosis. The researchers also found several clinical drugs, chemical compounds, phytochemicals, and miRNAs inhibited doxorubicin-induced cardiotoxicity by targeting ERS. The present review aims to outline the interactions between ERS and other mechanisms in doxorubicin-induced cardiotoxicity and summarize ERS's role in this type of cardiotoxicity. Additionally, the review enumerates several clinical drugs, phytochemicals, chemical compounds, and miRNAs targeting ERS for considering therapeutic regimens that address doxorubicin-induced cardiotoxicity.

Precision Treatment of Anthracycline-Induced Cardiotoxicity: An Updated Review

OPINION STATEMENT

Anthracycline (ANT)-induced cardiotoxicity (AIC) is a particularly prominent form of cancer therapy-related cardiovascular toxicity leading to the limitations of ANTs in clinical practice. Even though AIC has drawn particular attention, the best way to treat it is remaining unclear. Updates to AIC therapy have been made possible by recent developments in research on the underlying processes of AIC. We review the current molecular pathways leading to AIC: 1) oxidative stress (OS) including enzymatic-induced and other mechanisms; 2) topoisomerase; 3) inflammatory response; 4) cardiac progenitor cell damage; 5) epigenetic changes; 6) renin-angiotensin-aldosterone system (RAAS) dysregulation. And we systematically discuss current prevention and treatment strategies and novel pathogenesis-based therapies for AIC: 1) dose reduction and change; 2) altering drug delivery methods; 3) antioxidants, dexrezosen, statina, RAAS inhibitors, and hypoglycemic drugs; 4) miRNA, natural phytochemicals, mesenchymal stem cells, and cardiac progenitor cells. We also offer a fresh perspective on the management of AIC by outlining the current dilemmas and challenges associated with its prevention and treatment.

Elucidation for the pharmacological effects and mechanism of Shen Bai formula in treating myocardial injury based on energy metabolism and serum metabolomic approaches

ETHNOPHARMACOLOGICAL RELEVANCE

Shen Bai formula (SBF) is a proven effective traditional Chinese medicine for treating viral myocarditis (VMC) sequelae in clinic, and myocardial injury is the pathological basis of VMC sequelae. However, the pharmacological action and mechanism of SBF have not been systematically elucidated.

AIM OF THE STUDY

In present research, the doxorubicin-induced myocardial injury rat model was used to evaluate the efficacy of SBF, and energy metabolism and metabolomics approaches were applied to elucidate the effects of SBF on myocardial injury.

MATERIALS AND METHODS

Through energy metabolism measurement system and UPLC-Q-TOF-MS/MS oriented blood metabolomics, directly reflected the therapeutic effect of SBF at a macro level, and identified biomarkers of myocardial injury in microcosmic, revealing its metabolomic mechanism.

RESULTS

Results showed that SBF significantly improved the electrocardiogram (ECG), heart rate (HR), extent of myocardial tissue lesion, and ratio of heart and spleen. In addition, the serum levels of AST, CK, LDH, α-HBDH, cTnI, BNP, and MDA decreased, whereas SOD and ATP activity and content increased. Moreover, SBF increased locomotor activity and basic daily metabolism in rats with myocardial injury, restoring their usual level of energy metabolism. A total of 45 potential metabolomic biomarkers were identified. Among them, 44 biomarkers were significantly recalled by SBF, including representative biomarkers arachidonic acid (AA), 12-HETE, prostaglandin J2 (PGJ2), 15-deoxy-Δ-12,14-PGJ2, 15-keto-PGE2, 15(S)-HPETE, 15(S)-HETE, 8,11,14-eicosatrienoic acid and 9(S)-HODE, which involved AA metabolism, biosynthesis of unsaturated fatty acids and linoleic acid metabolism.

CONCLUSION

We successfully replicated a myocardial injury rat model with the intraperitoneal injection of doxorubicin, and elucidated the mechanism of SBF in treating myocardial injury. This key mechanism may be achieved by targeting action on COX, Alox, CYP, and 15-PGDH to increase or decrease the level of myocardial injury biomarker, and then emphatically interven in AA metabolism, biosynthesis of unsaturated fatty acids and linoleic acid metabolism, and participate in regulating purine metabolism, sphingolipid metabolism, primary bile acid biosynthesis, and steroid hormone synthesis.

Silk Protein-Based Nanoporous Microsphere for Controllable Drug Delivery through Self-Assembly in Ionic Liquid System

Ionic liquids (ILs) showed a promising application prospect in the field of biomedicine due to their unique recyclability, modifiability, and structure adjustability. In this study, nanoporous microsphere of silk protein and blending with poly(d,l-lactic acid) as model drug delivery was fabricated, respectively, through an IL-induced self-assembly method. Their morphology, structure, and thermal properties were comparably investigated through scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, differential scanning calorimetry, X-ray diffraction, and thermogravimetric analyses, and the interaction mechanisms were also discussed to elucidate the effect of structure on drug delivery kinetics. The pure protein exhibited a bigger nanopore size in the microsphere compared to the composite one, facilitating more effective drug loading up to 88.7%. However, drug release was over 53.5% for the composite during initial 4 h, while pure protein was only about half of the composite. Both of them exhibited sustained slow release after 24 h and anticancer efficacy. Furthermore, the favorable compatibility between drug and microsphere vehicle was found and experienced improved thermal stability upon encapsulation, which could protect the drug molecules in high temperature at 200 °C. When the protein and its composite self-assembled to microspheres in ILs due to electrostatic and hydrophobic interaction, the drug could be infiltrated into the nanoporous matrix through biophysical action, and the protein structure displayed reversible transition during delivery. The sustained slow release from pure SF was attributed to the high β-sheet block action and strong drug-protein interactions, whose strength could be tuned through blending poly(d,l-lactic acid) with protein. These findings indicated that the SF-based nanoporous microspheres formed from IL self-assembled system are an ideal and potential drug delivery vehicle which can be incorporated into various biomaterials in the future.

Doxorubicin-induced cardiotoxicity and risk factors

Doxorubicin (DOX) is an anthracycline antibiotic widely used as a chemotherapeutic agent to treat solid tumours and hematologic malignancies. Although useful in the treatment of cancers, the benefit of DOX is limited due to its cardiotoxic effect that is observed in a large number of patients. In the literature, there is evidence that the presence of various factors may increase the risk of developing DOX-induced cardiotoxicity. A better understanding of the role of these different factors in DOX-induced cardiotoxicity may facilitate the choice of the therapeutic approach in cancer patients suffering from various cardiovascular risk factors. In this review, we therefore discuss the latest findings in both preclinical and clinical research suggesting a link between DOX-induced cardiotoxicity and various risk factors including sex, age, ethnicity, diabetes, dyslipidaemia, obesity, hypertension, cardiovascular disease and co-medications.

Acute endoplasmic reticulum stress-induced mitochondria respiratory chain damage: The role of activated calpains

The induction of acute endoplasmic reticulum (ER) stress damages the electron transport chain (ETC) in cardiac mitochondria. Activation of mitochondria-localized calpain 1 (CPN1) and calpain 2 (CPN2) impairs the ETC in pathological conditions, including aging and ischemia-reperfusion in settings where ER stress is increased. We asked if the activation of calpains causes the damage to the ETC during ER stress. Control littermate and CPNS1 (calpain small regulatory subunit 1) deletion mice were used in the current study. CPNS1 is an essential subunit required to maintain CPN1 and CPN2 activities, and deletion of CPNS1 prevents their activation. Tunicamycin (TUNI, 0.4 mg/kg) was used to induce ER stress in C57BL/6 mice. Cardiac mitochondria were isolated after 72 h of TUNI treatment. ER stress was increased in both control littermate and CPNS1 deletion mice with TUNI treatment. The TUNI treatment activated both cytosolic and mitochondrial CPN1 and 2 (CPN1/2) in control but not in CPNS1 deletion mice. TUNI treatment led to decreased oxidative phosphorylation and complex I activity in control but not in CPNS1 deletion mice compared to vehicle. The contents of complex I subunits, including NDUFV2 and ND5, were decreased in control but not in CPNS1 deletion mice. TUNI treatment also led to decreased oxidation through cytochrome oxidase (COX) only in control mice. Proteomic study showed that subunit 2 of COX was decreased in control but not in CPNS1 deletion mice. Our results provide a direct link between activation of CPN1/2 and complex I and COX damage during acute ER stress.

Endoplasmic Reticulum Stress and Metabolism in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer, accounting for 85% to 90% of all liver cancer cases. It is a hepatocyte-derived primary tumor, causing 550,000 deaths per year, ranking it as one of the most common cancers worldwide. The liver is a highly metabolic organ with multiple functions, including digestion, detoxification, breakdown of fats, and production of bile and cholesterol, in addition to storage of vitamins, glycogen, and minerals, and synthesizing plasma proteins and clotting factors. Due to these fundamental and diverse functions, the malignant transformation of hepatic cells can have a severe impact on the liver's metabolism. Furthermore, tumorigenesis is often accompanied by activation of the endoplasmic reticulum (ER) stress pathways, which are known to be highly intertwined with several metabolic pathways. Because HCC is characterized by changes in the metabolome and by an aberrant activation of the ER stress pathways, the aim of this review was to summarize the current knowledge that links ER stress and metabolism in HCC, thereby focusing on potential therapeutic targets.

Protective effect of vitamin B6 against doxorubicin-induced cardiotoxicity by modulating NHE1 expression

Doxorubicin (DOX) has been used to treat various types of cancer, but its application is limited due to its heart toxicity as well as other drawbacks. Chronic inhibition of Na+ /H+ exchanger (NHE1) reduces heart failure and reduces the production of reactive oxygen species (ROS); vitamin B6 (VitB6 ) has been demonstrated to have a crucial role in antioxidant mechanism. So, this study was designed to explore the effect of VitB6 supplement on the DOX-induced cardiotoxicity and to imply whether NHE1 is involved. Ultrasonic cardiogram analysis revealed that VitB6 supplement could alleviate DOX-induced cardiotoxicity; hematoxylin and eosin (HE) and Masson's staining further confirmed this effect. Furthermore, VitB6 supplement exhibited significant antioxidative stress and antiapoptosis effect, which was evidenced by decreased serum malondialdehyde (MDA) content and increased serum superoxide dismutase (SOD) content, and decreased Bcl-2-associated X protein/B-cell lymphoma-2 ratio, respectively. Collectively, VitB6 supplement may exert antioxidative and antiapoptosis effects to improve cardiac function by decreasing NHE1 expression and improve DOX-induced cardiotoxicity.

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.

Endoplasmic reticulum homeostasis: a potential target for diabetic nephropathy

The endoplasmic reticulum (ER) is the most vigorous organelle in intracellular metabolism and is involved in physiological processes such as protein and lipid synthesis and calcium ion transport. Recently, the abnormal function of the ER has also been reported to be involved in the progression of kidney disease, especially in diabetic nephropathy (DN). Here, we reviewed the function of the ER and summarized the regulation of homeostasis through the UPR and ER-phagy. Then, we also reviewed the role of abnormal ER homeostasis in residential renal cells in DN. Finally, some ER stress activators and inhibitors were also summarized, and the possibility of maintaining ER homeostasis as a potential therapeutic target for DN was discussed.

LCZ696 (sacubitril/valsartan) mitigates cyclophosphamide-induced premature ovarian failure in rats; the role of TLR4/NF-κB/NLRP3/Caspase-1 signaling pathway

AIM

Cyclophosphamide (CP) is used to treat a variety of cancers and autoimmune illnesses. CP has been found to frequently cause premature ovarian failure (POF). The study's objective was to assess LCZ696's potential for protection against CP-induced POF in a rat model.

MAIN METHODS

Rats were randomly assigned into seven groups as follows: control, valsartan (VAL), LCZ696, CP, CP + VAL, CP + LCZ696, and CP + triptorelin (TRI). Ovarian malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD), interleukin-18 (IL-18), IL-1β, and tumor necrosis factor-alpha (TNF-α) were assessed using ELISA. Serum anti-mullerian hormone (AMH), estrogen, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) were also measured using ELISA. The expression of NLRP3/Caspase-1/GSDMD C-NT and TLR4/MYD88/NF-B P65 proteins was estimated using western blot assay. The histopathology of the ovaries was also investigated. The estrous cycle, body, and ovarian weights were also monitored.

KEY FINDINGS

CP treatment significantly elevated levels of MDA, IL-18, IL-1β, TNF-α, FSH, LH, and up-regulated TLR4/NF-κB/NLRP3/Caspase-1 proteins, as compared to the control group, however, ovarian follicles count, and levels of GSH, SOD, AMH, and estrogen were reduced with CP administration. All the aforementioned biochemical and histological abnormalities were considerably alleviated by the LCZ696 therapy compared to valsartan alone.

SIGNIFICANCE

LCZ696 effectively mitigated CP-induced POF, offering promising protection that could be related to its suppression power on NLRP3-induced pyroptosis and TLR4/NF-B P65 pathway.

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.

Neprilysin Inhibition in the Prevention of Anthracycline-Induced Cardiotoxicity

Anthracycline-induced cardiotoxicity (AIC) poses a clinical challenge in the management of cancer patients. AIC is characterized by myocardial systolic dysfunction and remodeling, caused by cardiomyocyte DNA damage, oxidative stress, mitochondrial dysfunction, or renin-angiotensin-aldosterone system (RAAS) dysregulation. In the past decade, after positive results of a PARADIGM-HF trial, a new class of drugs, namely angiotensin receptor/neprilysin inhibitors (ARNi), was incorporated into the management of patients with heart failure with reduced ejection fraction. As demonstrated in a variety of preclinical studies of cardiovascular diseases, the cardioprotective effects of ARNi administration are associated with decreased oxidative stress levels, the inhibition of myocardial inflammatory response, protection against mitochondrial damage and endothelial dysfunction, and improvement in the RAAS imbalance. However, data on ARNi's effectiveness in the prevention of AIC remains limited. Several reports of ARNi administration in animal models of AIC have shown promising results, as ARNi prevented ventricular systolic dysfunction and electrocardiographic changes and ameliorated oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress, and the inflammatory response associated with anthracyclines. There is currently an ongoing PRADAII trial aimed to assess the efficacy of ARNi in patients receiving breast cancer treatment, which is expected to be completed by late 2025.

Chemical Chaperones to Inhibit Endoplasmic Reticulum Stress: Implications in Diseases

The endoplasmic reticulum (ER) is responsible for structural transformation or folding of de novo proteins for transport to the Golgi. When the folding capacity of the ER is exceeded or excessive accumulation of misfolded proteins occurs, the ER enters a stressed condition (ER stress) and unfolded protein responses (UPR) are triggered in order to rescue cells from the stress. Recovery of ER proceeds toward either survival or cell apoptosis. ER stress is implicated in many pathologies, such as diabetes, cardiovascular diseases, inflammatory diseases, neurodegeneration, and lysosomal storage diseases. As a survival or adaptation mechanism, chaperone molecules are upregulated to manage ER stress. Chemical versions of chaperone have been developed in search of drug candidates for ER stress-related diseases. In this review, synthetic or semi-synthetic chemical chaperones are categorized according to potential therapeutic area and listed along with their chemical structure and activity. Although only a few chemical chaperones have been approved as pharmaceutical drugs, a dramatic increase in literatures over the recent decades indicates enormous amount of efforts paid by many researchers. The efforts warrant clearer understanding of ER stress and the related diseases and consequently will offer a promising drug discovery platform with chaperone activity.

Tunicamycin-Induced Endoplasmic Reticulum Stress Damages Complex I in Cardiac Mitochondria

BACKGROUND

Induction of acute ER (endoplasmic reticulum) stress using thapsigargin contributes to complex I damage in mouse hearts. Thapsigargin impairs complex I by increasing mitochondrial calcium through inhibition of Ca²⁺-ATPase in the ER. Tunicamycin (TUNI) is used to induce ER stress by inhibiting protein folding. We asked if TUNI-induced ER stress led to complex I damage.

METHODS

TUNI (0.4 mg/kg) was used to induce ER stress in C57BL/6 mice. Cardiac mitochondria were isolated after 24 or 72 h following TUNI treatment for mitochondrial functional analysis.

RESULTS

ER stress was only increased in mice following 72 h of TUNI treatment. TUNI treatment decreased oxidative phosphorylation with complex I substrates compared to vehicle with a decrease in complex I activity. The contents of complex I subunits including NBUPL and NDUFS7 were decreased in TUNI-treated mice. TUNI treatment activated both cytosolic and mitochondrial calpain 1. Our results indicate that TUNI-induced ER stress damages complex I through degradation of its subunits including NDUFS7.

CONCLUSION

Induction of the ER stress using TUNI contributes to complex I damage by activating calpain 1.

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.

Effects of Valsartan on LN, FN, MDA, Renal Tissue Fibrosis, and Inflammatory Infiltration in DN Rats

The effects of valsartan on laminin (LN), fibronectin (FN), malondialdehyde (MDA), renal tissue fibrosis, and inflammatory infiltration in diabetic nephropathy (DN) rats are explored. A total of 42 SPF male Sprague D (SD) rats are selected and randomly divided into normal set, model set, valsartan low-dose and high-dose sets, and metformin set with 7 rats in each set. The kidney tissue of all rats is collected after administration. The standard of protein mRNA in kidney tissues is detected by real-time fluorescence quantitative polymerase chain reaction (PCR) method, and the protein standard in kidney tissues is detected by western blot. The experimental results show that the application of valsartan to DN rats can effectively relieve the morphology of the rat kidney tissue, enhance the protein expression in the kidney tissue of the DN rats, and reduce the fibrosis and inflammatory infiltration of the kidney tissue.