Elabela blunts doxorubicin-induced oxidative stress and ferroptosis in rat aortic adventitial fibroblasts by activating the KLF15/GPX4 signaling.

Doxorubicin (DOX) is a chemotherapeutic drug for a variety of malignancies, while its application is restricted by the cardiovascular toxic effects characterized by oxidative stress. Ferroptosis is a novel iron-dependent regulated cell death driven by lipid peroxidation. Our study aimed to investigate the role of Elabela (ELA) in DOX-induced oxidative stress and ferroptosis. In cultured rat aortic adventitial fibroblasts (AFs), stimulation with DOX dramatically induced cytotoxicity with reduced cell viability and migration ability, and enhanced lactate dehydrogenase (LDH) activity. Importantly, ELA and ferrostatin-1 (Fer-1) mitigated DOX-mediated augmentation of reactive oxygen species (ROS) in rat aortic AFs, accompanied by upregulated levels of Nrf2, SLC7A11, GPX4, and GSH. In addition, ELA reversed DOX-induced dysregulation of apoptosis- and inflammation-related factors including Bax, Bcl2, interleukin (IL)-1ß, IL6, IL-10, and CXCL1. Intriguingly, knockdown of Krüppel-like factor 15 (KLF15) by siRNA abolished ELA-mediated alleviation of ROS production and inflammatory responses. More importanly, KLF15 siRNA impeded the beneficial roles of ELA in DOX-pretreated rat aortic AFs by suppressing the Nrf2/SLC7A11/GPX4 signaling. In conclusion, ELA prevents DOX-triggered promotion of cytotoxicity, and exerts anti-oxidative and anti-ferroptotic effects in rat aortic AFs via activation of the KLF15/GPX4 signaling, indicating a promising therapeutic value of ELA in antagonizing DOX-mediated cardiovascular abnormality and disorders.

Sirtuin 7 mitigates renal ferroptosis, fibrosis and injury in hypertensive mice by facilitating the KLF15/Nrf2 signaling.

Hypertension is one of the leading causes of chronic kidney disease characterized with renal fibrosis. This study aimed to investigate roles and mechanisms of sirtuin 7 (SIRT7) in hypertensive renal injury. Mini-pumps were implanted to male C57BL/6 mice to deliver angiotensin (Ang) Ⅱ (1.5 mg/kg/d) or saline for 2 weeks. Ang Ⅱ infusion resulted in marked increases in systolic blood pressure levels, renal ferroptosis and interstitial fibrosis in hypertensive mice, concomitantly with downregulated SIRT7 and Krüppel-like factor 15 (KLF15) levels. Notably, administration of recombinant adeno-associated virus-SIRT7 or ferroptosis inhibitor ferrostatin-1 effectively mitigated Ang Ⅱ-triggered renal ferroptosis, epithelial-mesenchymal transition (EMT), interstitial fibrosis, renal functional and structural injury in hypertensive mice by blunting the KIM-1/NOX4 signaling and enforcing the KLF15/Nrf2 and xCT/GPX4 signaling, respectively. In primary cultured mouse renal tubular epithelial cells (TECs), Ang Ⅱ pretreatment led to repressed SIRT7 expression and augmented ferroptosis as well as partial EMT, which were substantially antagonized by rhSIRT7 or ferrostatin-1 administration. Additionally, both Nrf2 inhibitor ML385 and KLF15 siRNA strikingly abolished the rhSIRT7-mediated beneficial roles in mouse renal TECs in response to Ang Ⅱ with reduced expression of Nrf2, xCT and GPX4. More importantly, ML385 administration remarkably amplified Ang Ⅱ-mediated ROS generation, lipid peroxidation and ferroptosis in renal TECs, which were significantly reversed by ferrostatin-1. In conclusion, SIRT7 alleviates renal ferroptosis, lipid peroxidation, and partial EMT under hypertensive status by facilitating the KLF15/Nrf2 signaling, thereby mitigating renal fibrosis, injury and dysfunction. Targeting SIRT7 signaling serves as a promising strategy for hypertension and hypertensive renal injury.

Sirtuin 7 serves as a promising therapeutic target for cardiorenal diseases.

Cardiovascular disorders and associated renal diseases account for the main cause of morbidity and mortality worldwide, necessitating the development of novel effective approaches for the prevention and treatment of cardiorenal diseases. Mammalian sirtuins (SIRTs) function as nicotinamide adenine dinucleotide (NAD+)-dependent protein/histone deacetylases. Seven members of SIRTs share a highly invariant catalytic core domain responsible for the specific enzymatic activity. Intriguingly, the broad distribution of SIRTs and alternative isoforms implicate its distinct functions in diverse cardiac and renal cells and tissue types. Notably, SIRT7 has been shown to exert beneficial effects in cardiorenal physiology and pathophysiology via modulation of senescence, DNA damage repair, ribosomal RNA synthesis, protein biosynthesis, angiogenesis, apoptosis, superoxide generation, cardiorenal metabolism, and dysfunction. Furthermore, SIRT7 has emerged as a critical modulator of a broad range of cellular activities including oxidative stress, inflammation response, endoplasmic reticulum stress, and mitochondrial homeostasis, which are all of great significance in postponing the progression of cardiorenal diseases. More importantly, SIRT7 has been implicated in cardiorenal hypertrophy, fibrosis, remodeling, heart failure, atherosclerosis as well as renal acid-base and electrolyte homeostasis as an essential regulator. In this article, we focus on the involvement in cardiorenal physiology and pathophysiology, diverse actions and underlying mechanisms of the SIRT7 signaling, highlighting its updated research progress in heart failure, atherosclerosis, diabetic nephropathy and other cardiorenal diseases. Targeting SIRT7 signaling could be potentially exploited as a therapeutic strategy aiming to prevent and treat cardiorenal diseases.

Elabela alleviates ferroptosis, myocardial remodeling, fibrosis and heart dysfunction in hypertensive mice by modulating the IL-6/STAT3/GPX4 signaling.

Hypertension-mediated pathological cardiac remodeling often progresses to heart failure. Elabela, mainly expressed in the cardiac microvascular endothelial cells (CMVECs), functions as a new endogenous ligand for apelin receptor. However, the exact roles of elabela in hypertension remain largely unclear. In this study, 10-week-old male C57BL/6 mice were randomly subjected to infusion of angiotensin (Ang) II (1.5 mg/kg/d) or saline for 2 weeks. Ang II infusion led to marked increases in systolic blood pressure levels and reduction of elabela levels in hypertensive mice with augmented myocardial hypertrophy and fibrosis. Furthermore, administration of elabela or ferroptosis inhibitor ferrostatin-1 significantly prevented Ang II-mediated pathological myocardial remodeling, dysfunction, and ultrastructural injury in hypertensive mice with downregulated expression of inflammation-, hypertrophy-, and fibrosis-related genes. Notably, elabela strikingly alleviated Ang II-induced upregulation of iron levels and lipid peroxidation in hypertensive mice by suppressing cardiac interleukin-6 (IL-6)/STAT3 signaling and activating the xCT/glutathione peroxidase (GPX4) signaling. In cultured CMVECs, exposure to Ang II resulted in a marked decrease in elabela levels and obvious increases in cellular ferroptosis, proliferation, inflammation, and superoxide production, which were rescued by elabela or ferrostatin-1 while were blocked by co-treatment with rhIL-6. Furthermore, knockdown of elabela by siRNA in CMVECs contributed to Ang II-mediated augmentations in cellular proliferation, migration, and oxidative stress in cultured cardiac fibroblasts and cardiomyocytes, respectively. In conclusion, elabela antagonizes Ang II-mediated promotion of CMVECs ferroptosis, adverse myocardial remodeling, fibrosis and heart dysfunction through modulating the IL-6/STAT3/GPX4 signaling pathway. Targeting elabela-APJ axis serves as a novel strategy for hypertensive heart diseases.

MicroRNA-122-5p Aggravates Angiotensin II-Mediated Myocardial Fibrosis and Dysfunction in Hypertensive Rats by Regulating the Elabela/Apelin-APJ and ACE2-GDF15-Porimin Signaling.

Hypertension is the leading risk factor for cardiovascular disorders. This study aimed to explore roles of microRNA (miR)-122-5p in hypertension. Angiotensin II (Ang II; 1.5 mg/kg/day) with an osmotic minipump was used to induce hypertensive rats pretreated by rAAV-miR-122-5p or rAAV-GFP, respectively. Notably, Ang II infusion caused marked increases in myocardial fibrosis, inflammation, oncosis, and oxidant injury in rats, which were aggravated by rAAV-miR-122-5p. RAAV-miR-122-5p exacerbated Ang II-mediated cardiac dysfunction and structural injury in hypertensive rats, with downregulated levels of apelin, elabela, ACE2, and GDF15, as well as upregulated expression of porimin and CTGF. In cultured rat cardiac fibroblasts, Ang II contributed to augmentation of cellular oncosis, migration, inflammation, and oxidative stress, with reduction of apelin, elabela, ACE2, and GDF15 levels, which were rescued by miR-122 inhibitor. In summary, miR-122-5p exacerbates myocardial fibrosis and dysfunction in hypertensive rats by modulating the elabela/apelin-ACE2-GDF15 signaling. MiR-122-5p has potential therapeutic significance for hypertension and hypertensive cardiac injury.

MicroRNA-122-5p promotes renal fibrosis and injury in spontaneously hypertensive rats by targeting FOXO3.

Hypertensive renal injury is accompanied by tubular interstitial fibrosis leading to increased risk for renal failure. This study aimed to explore the influences of miR-122-5p in hypertension-mediated renal fibrosis and damage. 14-week-old male SHR and WKY rats were randomly assigned to treat with rAAV-miR-122-5p or rAAV-GFP for 8 weeks. There were marked increases in miR-122-5p and Kim-1 levels and decreases in FOXO3 and SIRT6 levels in hypertensive rats. Transfection with rAAV-miR-122-5p triggered exacerbation of renal fibrosis, apoptosis and inflammatory injury in SHR, associated with downregulated levels of FOXO3, SIRT6, ATG5 and BNIP3 as well as upregulated expression of Kim-1, NOX4, CTGF, and TGF-ß1. In cultured primary mouse renal tubular interstitial fibroblasts, exposure to angiotensin II resulted in obvious downregulation of FOXO3, SIRT6, ATG5, BNIP3 and nitric oxide levels as well as augmented cellular migration, oxidative stress, and inflammation, which were exacerbated by miR-122-5p mimic while rescued by miR-122-5p inhibitor and rhFOXO3, respectively. Notably, knockdown of FOXO3 strikingly blunted cellular protective effects of miR-122-5p inhibitor. In summary, miR-122-5p augments renal fibrosis, inflammatory and oxidant injury in hypertensive rats by suppressing the expression of FOXO3. Pharmacological inhibition of miR-122-5p has potential therapeutic significance for hypertensive renal injury and fibrosis-related kidney diseases.

Abnormal apelin-ACE2 and SGLT2 signaling contribute to adverse cardiorenal injury in patients with COVID-19.

BACKGROUND: Angiotensin converting enzyme 2 (ACE2) has recently been identified as the functional receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent response for novel coronavirus disease 2019 (COVID-19). This study aimed to explore the roles of ACE2, apelin and sodium-glucose cotransporter 2 (SGLT2) in SARS-CoV-2-mediated cardiorenal damage. METHODS AND RESULTS: The published RNA-sequencing datasets of cardiomyocytes infected with SARS-CoV-2 and COVID-19 patients were used. String, UMAP plots and single cell RNA sequencing data were analyzed to show the close relationship and distinct cardiorenal distribution patterns of ACE2, apelin and SGLT2. Intriguingly, there were decreases in ACE2 and apelin expression as well as marked increases in SGLT2 and endothelin-1 levels in SARS-CoV-2-infected cardiomyocytes, animal models with diabetes, acute kidney injury, heart failure and COVID-19 patients. These changes were linked with downregulated levels of interleukin (IL)-10, superoxide dismutase 2 and catalase as well as upregulated expression of profibrotic genes and pro-inflammatory cytokines/chemokines. Genetic ACE2 deletion resulted in upregulation of pro-inflammatory cytokines containing IL-1ß, IL-6, IL-17 and tumor necrosis factor α. More importantly, dapagliflozin strikingly alleviated cardiorenal fibrosis in diabetic db/db mice by suppressing SGLT2 levels and potentiating the apelin-ACE2 signaling. CONCLUSION: Downregulation of apelin and ACE2 and upregulation of SGLT2, endothelin-1 and pro-inflammatory cytokines contribute to SARS-CoV-2-mediated cardiorenal injury, indicating that the apelin-ACE2 signaling and SGLT2 inhibitors are potential therapeutic targets for COVID-19 patients.

Expression Profiles of Circular RNA in Aortic Vascular Tissues of Spontaneously Hypertensive Rats.

Background: Circular RNAs (circRNAs), as a kind of endogenous non-coding RNA, have been implicated in ischemic heart diseases and vascular diseases. Based on theirs high stability with a closed loop structure, circRNAs function as a sponge and bind specific miRNAs to exert inhibitory effects in heart and vasculature, thereby regulating their target gene and protein expression, via competitive endogenous RNA (ceRNA) mechanism. However, the exact roles and underlying mechanisms of circRNAs in hypertension and related cardiovascular diseases remain largely unknown. Methods and Results: High-throughput RNA sequencing (RNA-seq) was used to analyze the differentially expressed (DE) circRNAs in aortic vascular tissues of spontaneously hypertensive rats (SHR). Compared with the Wistar-Kyoto (WKY) rats, there were marked increases in the levels of systolic blood pressure, diastolic blood pressure and mean blood pressure in SHR under awake conditions via the tail-cuff methodology. Totally, compared with WKY rats, 485 DE circRNAs were found in aortic vascular tissues of SHR with 279 up-regulated circRNAs and 206 down-regulated circRNAs. Furthermore, circRNA-target microRNAs (miRNAs) and the target messenger RNAs (mRNAs) of miRNAs were predicted by the miRanda and Targetscan softwares, respectively. Additionally, real-time RT-PCR analysis verified that downregulation of rno_circRNA_0009197, and upregulation of rno_circRNA_0005818, rno_circRNA_0005304, rno_circRNA_0005506, and rno_circRNA_0009301 were observed in aorta of SHR when compared with that of WKY rats. Then, the potential ceRNA regulatory mechanism was constructed via integrating 5 validated circRNAs, 31 predicted miRNAs, and 266 target mRNAs. More importantly, three hub genes (NOTCH1, FOXO3, and STAT3) were recognized according to PPI network and three promising circRNA-miRNA-mRNA regulatory axes were found in hypertensive rat aorta, including rno_circRNA_0005818/miR-615/NOTCH1, rno_circRNA_0009197/ miR-509-5p/FOXO3, and rno_circRNA_0005818/miR-10b-5p/STAT3, respectively. Conclusions: Our results demonstrated for the first time that circRNAs are expressed aberrantly in aortic vascular tissues of hypertensive rats and may serve as a sponge linking with relevant miRNAs participating in pathogenesis of hypertension and related ischemic heart diseases via the circRNA-miRNA-mRNA ceRNAnetwork mechanism.