SGK3 deficiency in macrophages suppresses angiotensin II-induced cardiac remodeling via regulating Ndufa13-mediated mitochondrial oxidative stress.

Infiltration of monocyte-derived macrophages plays a crucial role in cardiac remodeling and dysfunction. The serum and glucocorticoid-inducible protein kinase 3 (SGK3) is a downstream factor of PI3K signaling, regulating various biological processes via an AKT-independent signaling pathway. SGK3 has been implicated in cardiac remodeling. However, the contribution of macrophagic SGK3 to hypertensive cardiac remodeling remains unclear. A cardiac remodeling model was established by angiotensin II (Ang II) infusion in SGK3-Lyz2-CRE (f/f, +) and wild-type mice to assess the function of macrophagic SGK3. Additionally, a co-culture system of SGK3-deficient or wild-type macrophages and neonatal rat cardiomyocytes (CMs) or neonatal rat fibroblasts (CFs) was established to evaluate the effects of SGK3 and the underlying mechanisms. SGK3 levels were significantly elevated in both peripheral blood mononuclear cells and serum from patients with heart failure. Macrophage SGK3 deficiency attenuated Ang II-induced macrophage infiltration, myocardial hypertrophy, myocardial fibrosis, and mitochondrial oxidative stress. RNA sequencing suggested Ndufa13 as the candidate gene in the effect of SGK3 on Ang II-induced cardiac remolding. Downregulation of Ndufa13 in CMs and CFs prevented the suppression of cardiac remodeling caused by SGK3 deficiency in macrophages. Mechanistically, the absence of SGK3 led to a reduction in IL-1ß secretion by inhibiting the NLRP3/Caspase-1/IL-1ß pathway in macrophages, consequently suppressing upregulated Ndufa13 expression and mitochondrial oxidative stress in CMs and CFs. This study provides new evidence that SGK3 is a potent contributor to the pathogenesis of hypertensive cardiac remodeling, and targeting SGK3 in macrophages may serve as a potential therapy for cardiac remodeling.

The inhibition of FTO attenuates the antifibrotic effect of leonurine in rat cardiac fibroblasts.

BACKGROUND: Myocardial fibrosis (MF) is a common pathological condition in cardiovascular diseases that often causes severe cardiac dysfunction. MF is characterized by changes in cardiomyocytes, cardiac fibroblasts (CFs), levels of collagen (Col) -1, -3, and overdeposition of the extracellular matrix. Our previous research showed that leonurine (LE) effectively inhibits collagen synthesis and differentiation of CFs, but the mechanism is not fully elucidated. Recent evidence indicates that fat mass and obesity-associated proteins (FTO) regulates the occurrence and development of MF. This study aimed to explore the role of FTO in the antifibrotic effects of LE. METHODS: Neonatal rat CFs were isolated, and induced using angiotensin II (Ang II) to establish a cell model of MF. Cell viability, wound healing and transwell assays were used to detect cell activity and migration ability. The protein and mRNA levels of MF-related factors were measured following stimulation with Ang II and LE under normal conditions or after FTO knockdown. The RNA methylation level was measured by dot blot assay. RESULTS: The results showed that LE (20, 40 µM) was not toxic to normal CFs. LE reduced the proliferation, migration and collagen synthesis of Ang II-induced CFs. Further investigation showed that FTO was downregulated by Ang II stimulation, whereas LE reversed this effect. FTO knockdown facilitated the migration of CFs, upregulated the protein levels of Col-3, α-SMA and Col-1 in Ang II and LE-stimulated CFs, and enhanced the fluorescence intensity of α-SMA. Furthermore, LE reduced N6-methyladenosine (m6A) RNA methylation, which was partially blocked by FTO knockdown. FTO knockdown also reduced the expression levels of p53 protein in Ang II and LE-stimulated CFs. CONCLUSIONS: Our findings suggest that the inhibition of FTO may attenuate the antifibrotic effect of LE in CFs, suggesting that FTO may serve as a key protein for anti-MF of LE.

Small extracellular vesicles associated miRNA in myocardial fibrosis.

Myocardial fibrosis involves the loss of cardiomyocytes, myocardial fibroblast proliferation, and a reduction in angiogenesis, ultimately leading to heart failure, Given its significant implications, it is crucial to explore novel therapies for myocardial fibrosis. Recently one emerging avenue has been the use of small extracellular vesicles (sEV)-carried miRNA. In this review, we summarize the regulatory role of sEV-carried miRNA in myocardial fibrosis. We explored not only the potential diagnostic value of circulating miRNA as biomarkers for heart disease but also the therapeutic implications of sEV-carried miRNA derived from various cellular sources and applications of modified sEV. This exploration is paramount for researchers striving to develop innovative, cell-free therapies as potential drug candidates for the management of myocardial fibrosis.

Exploring the role of iNOS in HFpEF-Related myocardial fibrosis: Involvement of PTEN-PI3K/AKT signaling pathway.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is a challenging condition to treat with myocardial fibrosis being a pivotal pathological component. Previous studies have suggested a role for inducible nitric oxide synthase (iNOS) in the progression of this condition, but the precise mechanisms remain unclear. This study aimed to investigate the role of iNOS in HFpEF-related myocardial fibrosis and identify potential therapeutic targets. METHODS: A 'two-hit' mouse model of HFpEF was established, and echocardiography, histopathology and biochemical analyses were performed. In vitro experiments were conducted in mouse cardiac fibroblasts, with iNOS overexpression and application of iNOS or phosphatidylinositol 3 kinase (PI3K) inhibitors. The iNOS-S-nitrosylated phosphatase and TENsin homolog (SNO-PTEN)-phosphorylated-protein kinase B (p-AKT) pathway was investigated, along with the effects on fibrotic markers and cell proliferation and migration. RESULTS: HFpEF mice exhibited significant cardiac dysfunction and fibrosis, with increased expression of iNOS, SNO-PTEN, and p-AKT, indicative of the activation of the iNOS-SNO-PTEN-p-AKT pathway. iNOS overexpression in mouse cardiac fibroblasts led to increased SNO-PTEN, decreased PTEN, activated phosphorylated PI3K (p-PI3K) and p-AKT, and enhanced cell proliferation and migration, as well as increased collagen I and III expression. The use of an iNOS inhibitor (L-NIL) or a PI3K inhibitor (LY294002) partially reversed these changes. CONCLUSION: Our findings suggest that the iNOS-SNO-PTEN-p-AKT pathway may play a crucial role in HFpEF-related myocardial fibrosis, with iNOS and PI3K inhibitors offering potential therapeutic benefits. These insights may pave the way for the development of effective drug therapies for HFpEF.

Identification of macrophage driver genes in fibrosis caused by different heart diseases based on omics integration.

BACKGROUND: Myocardial fibrosis, a hallmark of heart disease, is closely associated with macrophages, yet the genetic pathophysiology remains incompletely understood. In this study, we utilized integrated single-cell transcriptomics and bulk RNA-seq analysis to investigate the relationship between macrophages and myocardial fibrosis across omics integration. METHODS: We examined and curated existing single-cell data from dilated cardiomyopathy (DCM), ischemic cardiomyopathy (ICM), myocardial infarction (MI), and heart failure (HF), and analyzed the integrated data using cell communication, transcription factor identification, high dimensional weighted gene co-expression network analysis (hdWGCNA), and functional enrichment to elucidate the drivers of macrophage polarization and the macrophage-to-myofibroblast transition (MMT). Additionally, we assessed the accuracy of single-cell data from the perspective of driving factors, cell typing, anti-fibrosis performance of left ventricular assist device (LVAD). Candidate drugs were screened using L1000FWD. RESULTS: All four heart diseases exhibit myocardial fibrosis, with only MI showing an increase in macrophage proportions. Macrophages participate in myocardial fibrosis through various fibrogenic molecules, especially evident in DCM and MI. Abnormal RNA metabolism and dysregulated transcription are significant drivers of macrophage-mediated fibrosis. Furthermore, profibrotic macrophages exhibit M1 polarization and increased MMT. In HF patients, those responding to LVAD therapy showed a significant decrease in driver gene expression, M1 polarization, and MMT. Drug repurposing identified cinobufagin as a potential therapeutic agent. CONCLUSION: Using integrated single-cell transcriptomics, we identified the drivers of macrophage-mediated myocardial fibrosis in four heart diseases and confirmed the therapeutic effect of LVAD on improving HF with single-cell accuracy, providing novel insights into the diagnosis and treatment of myocardial fibrosis.

IL-37 ameliorates myocardial fibrosis by regulating mtDNA-enriched vesicle release in diabetic cardiomyopathy mice.

BACKGROUND: Diabetic cardiomyopathy (DCM), a serious complication of diabetes, leads to structural and functional abnormalities of the heart and ultimately evolves to heart failure. IL-37 exerts a substantial influence on the regulation of inflammation and metabolism. Whether IL-37 is involved in DCM is unknown. METHODS: The plasma samples were collected from healthy controls, diabetic patients and DCM patients, and the level of IL-37 and its relationship with heart function were observed. The changes in cardiac function, myocardial fibrosis and mitochondrial injury in DCM mice with or without IL-37 intervention were investigated in vivo. By an in vitro co-culture approach involving HG challenge of cardiomyocytes and fibroblasts, the interaction carried out by cardiomyocytes on fibroblast profibrotic activation was studied. Finally, the possible interactive mediator between cardiomyocytes and fibroblasts was explored, and the intervention role of IL-37 and its relevant molecular mechanisms. RESULTS: We showed that the level of plasma IL-37 in DCM patients was upregulated compared to that in healthy controls and diabetic patients. Both recombinant IL-37 administration or inducing IL-37 expression alleviated cardiac dysfunction and myocardial fibrosis in DCM mice. Mechanically, hyperglycemia impaired mitochondria through SIRT1/AMPK/PGC1α signaling, resulting in significant cardiomyocyte apoptosis and the release of extracellular vesicles containing mtDNA. Fibroblasts then engulfed these mtDNA-enriched vesicles, thereby activating TLR9 signaling and the cGAS-STING pathway to initiate pro-fibrotic process and adverse remodeling. However, the presence of IL-37 ameliorated mitochondrial injury by preserving the activity of SIRT1-AMPK-PGC1α axis, resulting in a reduction in release of mtDNA-enriched vesicle and ultimately attenuating the progression of DCM. CONCLUSIONS: Collectively, our study demonstrates a protective role of IL-37 in DCM, offering a promising therapeutic agent for this disease.

HTRA1-driven detachment of type I collagen from endoplasmic reticulum contributes to myocardial fibrosis in dilated cardiomyopathy.

BACKGROUND: The aberrant secretion and excessive deposition of type I collagen (Col1) are important factors in the pathogenesis of myocardial fibrosis in dilated cardiomyopathy (DCM). However, the precise molecular mechanisms underlying the synthesis and secretion of Col1 remain unclear. METHODS AND RESULTS: RNA-sequencing analysis revealed an increased HtrA serine peptidase 1 (HTRA1) expression in patients with DCM, which is strongly correlated with myocardial fibrosis. Consistent findings were observed in both human and mouse tissues by immunoblotting, quantitative reverse transcription polymerase chain reaction (qRT-PCR), immunohistochemistry, and immunofluorescence analyses. Pearson's analysis showed a markedly positive correlation between HTRA1 level and myocardial fibrosis indicators, including extracellular volume fraction (ECV), native T1, and late gadolinium enhancement (LGE), in patients with DCM. In vitro experiments showed that the suppression of HTRA1 inhibited the conversion of cardiac fibroblasts into myofibroblasts and decreased Col1 secretion. Further investigations identified the role of HTRA1 in promoting the formation of endoplasmic reticulum (ER) exit sites, which facilitated the transportation of Col1 from the ER to the Golgi apparatus, thereby increasing its secretion. Conversely, HTRA1 knockdown impeded the retention of Col1 in the ER, triggering ER stress and subsequent induction of ER autophagy to degrade misfolded Col1 and maintain ER homeostasis. In vivo experiments using adeno-associated virus-serotype 9-shHTRA1-green fluorescent protein (AAV9-shHTRA1-GFP) showed that HTRA1 knockdown effectively suppressed myocardial fibrosis and improved left ventricular function in mice with DCM. CONCLUSIONS: The findings of this study provide valuable insights regarding the treatment of DCM-associated myocardial fibrosis and highlight the therapeutic potential of targeting HTRA1-mediated collagen secretion.

The diagnostic value of sST2 for myocardial fibrosis in idiopathic inflammatory myopathies in subclinical stage of cardiac involvement.

OBJECTIVE: Myocardial fibrosis occurs in the early subclinical stage of cardiac involvement in idiopathic inflammatory myopathies (IIMs). Soluble suppression of tumorigenicity 2 (sST2) is known to have an immunomodulatory impact during autoimmune disease development. The current study investigated the diagnostic value of sST2 for myocardial fibrosis during early stage of cardiac involvement in IIM. METHODS: A total of 44 IIM patients with normal heart function and 32 age- and gender-matched healthy controls (HCs) were enrolled. Serum sST2 levels were measured by ELISA and cardiac magnetic resonance (CMR) parameters for myocardial fibrosis [native T1, extracellular volume (ECV), late-gadolinium enhancement (LGE)] and oedema (T2 values) were analysed. RESULTS: IIM patients had significantly higher sST2 levels than HCs [67.5 ng/ml (s.d. 30.4)] vs 14.4 (5.5), P < 0.001] and levels correlated positively with diffuse myocardial fibrosis parameters, native T1 (r = 0.531, P = 0.000), ECV (r = 0.371, P = 0.013) and focal myocardial fibrosis index and LGE (r = 0.339, P = 0.024) by Spearman's correlation analysis. sST2 was an independent predictive factor for diffuse and focal myocardial fibrosis after adjustment for age, gender, BMI and ESR. Risk increased ≈15.4% for diffuse [odds ratio (OR) 1.154 (95% CI 1.021, 1.305), P = 0.022] and 3.8% for focal [OR 1.038 (95% CI 1.006, 1.072), P = 0.020] myocardial fibrosis per unit increase of sST2. Cut-off values for diagnosing diffuse and focal myocardial fibrosis were sST2 ≥51.3 ng/ml [area under the curve (AUC) = 0.942, sensitivity = 85.7%, specificity = 98.9%, P < 0.001] and 53.3 ng/ml (AUC = 0.753, sensitivity = 87.5%, specificity = 58.3%, P < 0.01), respectively. CONCLUSION: sST2 showed a marked elevation during the subclinical stage of cardiac involvement in IIM and has potential as a biomarker for predicting diffuse and focal myocardial fibrosis in IIM.

The presence of abnormal septal motion on echocardiography is a predictor of abnormal cardiac magnetic resonance in systemic sclerosis.

OBJECTIVES: We aimed to perform a comprehensive analysis of the ECG, two-dimensional echocardiography (2DE) and cardiac MRI (CMR) findings in patients with systemic sclerosis (SSc), and also to investigate correlations between CMR findings and some ECG and echocardiography (ECHO) results. METHODS: We retrospectively analysed data from patients with SSc who were regularly seen at our outpatient referral centre, all assessed with ECG, Doppler ECHO and CMR. RESULTS: Ninety-three patients were included; mean (s.d.) age of 48.5 (10.3) years, 86% female, 52% diffuse SSc. Eighty-four (90%) of the patients had sinus rhythm. The most common ECG finding was the left anterior fascicular block, recorded in 26 patients (28%). The abnormal septal motion (ASM) was found in 43 (46%) patients on ECHO. Myocardial involvement (inflammation or fibrosis), as assessed by multiparametric CMR, was present in >50% of our patients. The age- and sex-adjusted model showed that ASM on ECHO increased significantly the odds of increased extracellular volume [odds ratio (OR) 4.43, 95% CI 1.73, 11.38], increased T1 Relaxation time (OR 2.67, 95% CI 1.09, 6.54), increased T2 Relaxation time (OR 2.56, 95% CI 1.05, 6.22), increased signal intensity ratio in T2-weighted imaging (OR 2.56, 95% CI 1.05, 6.22), presence of late gadolinium enhancement (OR 3.85, 95% CI 1.52, 9.76) and mid-wall fibrosis (OR 3.64, 95% CI 1.48, 8.96). CONCLUSION: This study indicates that the presence of ASM on ECHO is a predictor of abnormal CMR in SSc patients, and a precise assessment of ASM may serve as an important point for selecting the patients that should be evaluated by CMR for early detection of myocardial involvement.

The impact of type 2 diabetes mellitus on the clinical profile, myocardial fibrosis, and prognosis in non-ischemic dilated cardiomyopathy: a prospective cohort study.

BACKGROUND: The impact of the coexistence of type 2 diabetes mellitus (T2DM) in patients with non-ischemic dilated cardiomyopathy (DCM) on clinical profiles, myocardial fibrosis, and outcomes remain incompletely understood. METHOD: A total of 1152 patients diagnosed with non-ischemic DCM were prospectively enrolled from June 2012 to October 2021 and categorized into T2DM and non-T2DM groups. Clinical characteristics, cardiac function, and myocardial fibrosis evaluated by CMR were compared between the two groups. The primary endpoint included both all-cause mortality and heart transplantation. Cause of mortality was classified into heart failure death, sudden cardiac death, and non-cardiac death. Cox regression analysis and Kaplan-Meier analysis were performed to identify the association between T2DM and clinical outcomes. Propensity score matching (PSM) cohort including 438 patients was analyzed to reduce the bias from confounding covariates. RESULTS: Among the 1152 included DCM patients, 155 (13%) patients had T2DM. Patients with T2DM were older (55 ± 12 vs. 47 ± 14 years, P < 0.001), had higher New York Heart Association (NYHA) functional class (P = 0.003), higher prevalence of hypertension (37% vs. 21%, P < 0.001), atrial fibrillation (31% vs. 16%, P < 0.001), lower left ventricular (LV) ejection fraction (EF) (23 ± 9% vs. 27 ± 12%, P < 0.001), higher late gadolinium enhancement (LGE) presence (55% vs. 45%, P = 0.02), and significantly elevated native T1 (1323 ± 81ms vs. 1305 ± 73ms, P = 0.01) and extracellular volume fraction (ECV) (32.7 ± 6.3% vs. 31.3 ± 5.9%, P = 0.01) values. After a median follow-up of 38 months (interquartile range: 20-57 months), 239 patients reached primary endpoint. Kaplan-Meier analysis showed that patients with T2DM had worse clinical outcomes compared with those without T2DM in the overall cohort (annual events rate: 10.2% vs. 5.7%, P < 0.001). T2DM was independently associated with an increased risk of primary endpoint in the overall (Hazard ratio [HR]: 1.61, 95% CI: 1.13-2.33, P = 0.01) and PSM (HR: 1.54, 95% CI: 1.05-2.24, P = 0.02) cohorts. Furthermore, T2DM was associated with a higher risk of heart failure death (P = 0.006) and non-cardiac death (P = 0.02), but not sudden cardiac death (P = 0.16). CONCLUSIONS: Patients with T2DM represented a more severe clinical profile and experienced more adverse outcomes compared to those without T2DM in a large DCM cohort. TRIAL REGISTRATION: Trial registration number: ChiCTR1800017058; URL: https://www. CLINICALTRIALS: gov .

Recent Progresses in the Multimodality Imaging Assessment of Myocardial Fibrosis.

Myocardial fibrosis, a common pathophysiological consequence of various cardiovascular diseases, is characterized by fibroblast activation and excessive deposition of extracellular matrix (ECM) collagen. Accumulating evidence indicates that myocardial fibrosis contributes to ventricular stiffness, systolic and diastolic dysfunction, and ultimately leads to the development of heart failure (HF). Early detection and targeted treatment of myocardial fibrosis is critical to reverse ventricular remodeling and improve clinical outcomes in patients with cardiovascular diseases. However, despite considerable progresses made in understanding molecular mechanisms of myocardial fibrosis, non-invasive imaging to assess myocardial fibrosis and guide clinical treatment is still not widely available, limiting the development of innovative treatment strategies. This review summarizes recent progresses of imaging modalities for detecting myocardial fibrosis, with a focus on nuclear medicine, echocardiography and cardiac magnetic resonance (CMR).

Multi-modality deep learning-based [68Ga]Ga-DOTA-FAPI-04 PET polar map generation: potential value in detecting reactive fibrosis after myocardial infarction.

PURPOSE: Generating polar map (PM) from [68Ga]Ga-DOTA-FAPI-04 PET images is challenging and inaccurate using existing automatic methods that rely on the myocardial anatomical integrity in PET images. This study aims to enhance the accuracy of PM generated from [68Ga]Ga-DOTA-FAPI-04 PET images and explore the potential value of PM in detecting reactive fibrosis after myocardial infarction and assessing its relationship with cardiac function. METHODS: We proposed a deep-learning-based method that fuses multi-modality images to compensate for the cardiac structural information lost in [68Ga]Ga-DOTA-FAPI-04 PET images and accurately generated PMs. We collected 133 pairs of [68Ga]Ga-DOTA-FAPI-04 PET/MR images from 87 ST-segment elevated myocardial infarction patients for training and evaluation purposes. Twenty-six patients were selected for longitudinal analysis, further examining the clinical value of PM-related imaging parameters. RESULTS: The quantitative comparison demonstrated that our method was comparable with the manual method and surpassed the commercially available software-PMOD in terms of accuracy in generating PMs for [68Ga]Ga-DOTA-FAPI-04 PET images. Clinical analysis revealed the effectiveness of [68Ga]Ga-DOTA-FAPI-04 PET PM in detecting reactive myocardial fibrosis. Significant correlations were demonstrated between the difference of baseline PM FAPI% and PM LGE%, and the change in cardiac function parameters (all p < 0.001), including LVESV% (r = 0.697), LVEDV% (r = 0.621) and LVEF% (r = -0.607). CONCLUSION: The [68Ga]Ga-DOTA-FAPI-04 PET PMs generated by our method are comparable to manually generated and sufficient for clinical use. The PMs generated by our method have potential value in detecting reactive fibrosis after myocardial infarction and were associated with cardiac function, suggesting the possibility of enhancing clinical diagnostic practices. TRIAL REGISTRATION: ClinicalTrials.gov (NCT04723953). Registered 26 January 2021.

Coronary Microvascular Dysfunction and Diffuse Myocardial Fibrosis in Patients With Type 2 Diabetes Using Quantitative Perfusion MRI.

BACKGROUND: Imaging techniques that quantitatively and automatically measure changes in the myocardial microcirculation in patients with diabetes are lacking. PURPOSE: To detect diabetic myocardial microvascular complications using a novel automatic quantitative perfusion MRI technique, and to explore the relationship between myocardial microcirculation dysfunction and fibrosis. STUDY TYPE: Prospective. SUBJECTS: 101 patients with type 2 diabetes mellitus (T2DM) (53 without and 48 with complications), 20 healthy volunteers. FIELD STRENGTH/SEQUENCE: 3.0T; modified Look-Locker inversion-recovery sequence; saturation recovery sequence and dual-bolus technique; segmented fast low-angle shot sequence. ASSESSMENT: All participants underwent MRI to determine the rest myocardial blood flow (MBF), stress MBF, myocardial perfusion reserve (MPR), and extracellular volume (ECV), which represents the extent of myocardial fibrosis. STATISTICAL TESTS: Kolmogorov-Smirnov test, Shapiro-Wilk test, Kruskal-Wallis H test, Mann-Whitney U test, chi-square test, Spearman correlation coefficient, multivariable linear regression analysis. P < 0.05 was considered statistically significant. RESULTS: The rest MBF was not significantly different between the T2DM without complications group (1.1, IQR: 0.9-1.3) and the control group (1.1, 1.0-1.3) (P = 1.000), but it was significantly lower in the T2DM with complications group (0.8, 0.6-1.0) than in both other groups. The stress MBF and MPR were significantly lower in the T2DM without complications group (1.9, 1.5-2.3, and 1.7, 1.4-2.1, respectively) than in the control group (3.0, 2.6-3.5, and 2.7, 2.4-3.1, respectively), and were also significantly lower in the T2DM with complications group (1.1, 0.9-1.4, and 1.4, 1.2-1.8, respectively) than in the T2DM without complications group. A decrease in MBF and MPR were significantly associated with an increase in the ECV. DATA CONCLUSION: Quantitative perfusion MRI can evaluate myocardial microcirculation dysfunction. In T2DM, there was a significant decrease in both MBF and MPR compared to healthy controls, with the decrease being significantly different between T2DM with and without complications groups. The decrease of MBF was significantly associated with the development of myocardial fibrosis, as determined by ECV. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 3.

Exosomal miR-15a-5p from cardiomyocytes promotes myocardial fibrosis.

The emergence of myofibroblasts is a key step in myocardial fibrosis, but the trigger for the transformation of cardiac fibroblasts into myofibroblasts remains not entirely clear. Exosomes play a key role between cardiomyocytes and cardiac fibroblasts. Here, we not only investigated the relationship between exosomes derived from angiotensin (Ang)-II-treated cardiomyocytes and cardiac fibroblasts, the underlying mechanisms were also explored. Ang-II-treated C57 male mice and mouse cardiac fibroblasts were employed for in vivo and in vitro experiments, respectively. Transmission electron microscopy nanoparticle tracking analysis, and western blot of CD9, CD63, CD81 were performed to identify exosomes; QRT-PCR was performed to detect miR-15a-5p expression; luciferase reporter assay was employed to determine the interaction between miR-15a-5p and dyrk2; western blot was performed to examine the protein levels of fibrosis markers; Counting Kit-8 was performed to determine cell viability; HE and Masson staining were performed to assess the pathological changes of myocardial tissues. MiR-15a-5p expression was found up-regulated in serum of myocardial fibrosis patients, serum and myocardial tissues of Ang-II-treated mice, and Ang-II-treated cardiomyocytes. Mechanically, exosomes from Ang-II-treated cardiomyocytes shuttled miR-15a-5p to cardiac fibroblasts, where miR-15a-5p dephosphorylated NFAT by targeting dyrk2 to promote cell viability and elevated the protein levels of α-smooth muscle actin, collagen type 1 α1 and collagen type 3 α1, thus promoting myocardial fibrosis. This study identified a novel molecular target for anti-fibrotic therapeutic interventions.

Microrna363-5p targets thrombospondin3 to regulate pathological cardiac remodeling.

Cardiac remodeling is an end-stage manifestation of multiple cardiovascular diseases, and microRNAs are involved in a variety of posttranscriptional regulatory processes. miR-363-5p targeting Thrombospondin3 (THBS3) has been shown to play an important regulatory role in vascular endothelial cells, but the roles of these two in cardiac remodeling are unknown. Firstly, we established an in vivo model of cardiac remodeling by transverse aortic narrow (TAC), and then we stimulated a human cardiomyocyte cell line (AC16) and a human cardiac fibroblast cell line (HCF) using 1 µmol/L angiotensin II (Ang II) to establish an in vitro model of cardiac hypertrophy and an in vitro model of myocardial fibrosis, respectively. In all three of the above models, we found a significant decreasing trend of miR-363-5p, suggesting that it plays a key regulatory role in the occurrence and development of cardiac remodeling. Subsequently, overexpression of miR-363-5p significantly attenuated myocardial hypertrophy and myocardial fibrosis in vitro as evidenced by reduced the area of AC16, the cell viability of HCFs, the relative expression of the protein of fetal genes (ANP, BNP, ß-MHC) and fibrosis marker (collagen I, collagen III, α-SMA), whereas inhibition of miR-363-5p expression showed the opposite trend. In addition, we also confirmed the targeted binding relationship between miR-363-5p and THBS3 by dual luciferase reporter gene assay, and the expression of THBS3 was directly inhibited by miR-363-5p. Moreover, overexpression of miR-363-5p with THBS3 simultaneously partially eliminated the delaying effect of miR-363-5p on myocardial hypertrophy and myocardial fibrosis in vitro. In conclusion, Overexpression of miR-363-5p attenuated the prohypertrophic and profibrotic effects of Ang II on AC16 and HCF by a mechanism related to the inhibition of THBS3 expression.

Remote myocardial fibrosis predicts adverse outcome in patients with myocardial infarction on clinical cardiovascular magnetic resonance imaging.

BACKGROUND: Heart failure (HF) most commonly occurs in patients who have had a myocardial infarction (MI), but factors other than MI size may be deterministic. Fibrosis of myocardium remote from the MI is associated with adverse remodeling. We aimed to 1) investigate the association between remote myocardial fibrosis, measured using cardiovascular magnetic resonance (CMR) extracellular volume fraction (ECV), and HF and death following MI, 2) identify predictors of remote myocardial fibrosis in patients with evidence of MI and determine the relationship with infarct size. METHODS: Multicenter prospective cohort study of 1199 consecutive patients undergoing CMR with evidence of MI on late gadolinium enhancement. Median follow-up was 1133 (895-1442) days. Cox proportional hazards modeling was used to identify factors predictive of the primary outcome, a composite of first hospitalization for HF (HHF) or all-cause mortality, post-CMR. Linear regression modeling was used to identify determinants of remote ECV. RESULTS: Remote myocardial fibrosis was a strong predictor of primary outcome (χ2: 15.6, hazard ratio [HR]: 1.07 per 1% increase in ECV, 95% confidence interval [CI]: 1.04-1.11, p < 0.001) and was separately predictive of both HHF and death. The strongest predictors of remote ECV were diabetes, sex, natriuretic peptides, and body mass index, but, despite extensive phenotyping, the adjusted model R2 was only 0.283. The relationship between infarct size and remote fibrosis was very weak. CONCLUSION: Myocardial fibrosis, measured using CMR ECV, is a strong predictor of HHF and death in patients with evidence of MI. The mechanisms underlying remote myocardial fibrosis formation post-MI remain poorly understood, but factors other than infarct size appear to be important.

Free-Breathing Non-Contrast T1ρ Dispersion MRI of Myocardial Interstitial Fibrosis in Comparison with Extracellular Volume Fraction.

BACKGROUND: Myocardial fibrosis is a common feature in various cardiac diseases. It causes adverse cardiac remodeling and is associated with poor clinical outcomes. Late gadolinium enhancement (LGE) and extracellular volume fraction (ECV) are the standard MRI techniques for detecting focal and diffuse myocardial fibrosis. However, these contrast-enhanced techniques require the administration of gadolinium contrast agents, which is not applicable to patients with gadolinium contraindications. To eliminate the need of contrast agents, we develop and apply an endogenous free-breathing T1ρ dispersion imaging technique (FB-MultiMap) for diagnosing diffuse myocardial fibrosis in a cohort with suspected cardiomyopathies. METHODS: The proposed FB-MultiMap technique, enabling T2, T1ρ and their difference (myocardial fibrosis index, mFI) quantification in a single scan was developed in phantoms and 15 healthy subjects. In the clinical study, 55 patients with suspected cardiomyopathies were imaged using FB-MultiMap, conventional native T1 mapping, LGE, and ECV imaging. The accuracy of the endogenous parameters for predicting increased ECV was evaluated using receiver operating characteristic (ROC) curve analysis. In addition, the correlation of native T1, T1ρ, and mFI with ECV was respectively assessed using Pearson correlation coefficients. RESULTS: FB-MultiMap showed a good agreement with conventional separate breath-hold mapping techniques in phantoms and healthy subjects. Considering all the patients, T1ρ was more accurate than mFI and native T1 for predicting increased ECV, with area under the curve (AUC) values of 0.91, 0.79 and 0.75, respectively, and showed stronger correlation with ECV (correlation coefficient r: 0.72 vs. 0.52 vs. 0.40). In the subset of 47 patients with normal T2 values, the diagnostic performance of mFI was significantly strengthened (AUC=0.90, r=0.83), outperforming T1ρ and native T1. CONCLUSION: The proposed free-breathing T1ρ dispersion imaging technique enabling simultaneous quantification of T2, T1ρ and mFI in a single scan has shown great potential for diagnosing diffuse myocardial fibrosis in patients with complex cardiomyopathies without contrast agents.

Screening Organic Components and Toxicogenic Structures from Regional Fine Particulate Matters Responsible for Myocardial Fibrosis in Male Mice.

Numerous studies indicate that fine particulate matters (PM2.5) and its organic components are urgent risk factors for cardiovascular diseases (CVDs). Combining toxicological experiments, effect-directed analyses, and nontarget identification, this study aims to explore whether PM2.5 exposure in coal-combustion areas induces myocardial fibrosis and how to identify the effective organic components and their toxic structures to support regional risk control. First, we constructed an animal model of real-world PM2.5 exposure during the heating season and found that the exposure impaired cardiac systolic function and caused myocardial fibrosis, with chemokine Ccl2-mediated inflammatory response being the key cause of collagen deposition. Then, using the molecular event as target coupled with two-stage chromatographic isolation and mass spectrometry analyses, we identified a total of 171 suspect organic compounds in the PM2.5 samples. Finally, using hierarchical characteristic fragment analysis, we predicted that 40 of them belonged to active compounds with 6 alert structures, including neopentane, butyldimethylamine, 4-ethylphenol, hexanal, decane, and dimethylaniline. These findings provide evidence for risk management and prevention of CVDs in polluted areas.

miR-135a Mediates Mitochondrial Oxidative Respiratory Function through SIRT1 to Regulate Atrial Fibrosis.

INTRODUCTION: This study aimed to explore the function of miR-135a in the progress of atrial fibrosis and the mechanism of miR-135a/SIRT1 (sirtuin 1) in human cardiac fibroblasts and mouse cardiac fibroblasts (MCFs) mediating the regulation of atrial fibrosis by mitochondrial oxidative respiration function. METHODS: Using Ang II (angiotensin II) to induce fibrosis in HCFs (human corneal fibroblasts) and MCF (Michigan Cancer Foundation, MCF) cells in vitro, the miRNA-seq results of previous studies were validated. Proliferative and invasive ability of HCFs and MCFs was detected by Cell Counting Kit-8 assay (CCK-8) and scratch experiment after overexpressing miR-135a in HCFs and MCF cells. Protein and mRNA expression was tested using Western blot and qPCR. The target of miR-135a was verified as SIRT1 by a luciferase reporter assay and the activities of the mitochondrial respiratory enzyme complexes I, II, III, and IV were determined colorimetrically. The activities of malondialdehyde, reactive oxygen species, and superoxide dismutase in cells were detected with enzyme-linked immunosorbent assay (ELISA). RESULTS: miR-135a expression was elevated in HCFs and MCFs cells in the Ang II group than control group. Overexpression of miR-135a could promote the proliferation, migration, oxidative stress, as well as fibrosis of cardiac fibroblasts and suppresses mitochondrial activity. In addition, we found SIRT1 was a target gene of miR-135a. What is more, the findings showed miR-135a promoted fibrosis in HCFs and MCFs cells acting through regulation of SIRT1. CONCLUSIONS: miR-135a mediates mitochondrial oxidative respiratory function through SIRT1 to regulate atrial fibrosis.

Arrhythmogenic right ventricular cardiomyopathy with sustained ventricular tachycardia: a case report.

INTRODUCTION: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an infrequent hereditary disorder distinguished by fibrofatty replacement of the myocardium in the right ventricular, which predisposes individuals to life-threatening arrhythmias. This case delineates an ARVC patient who suffered recurrent bouts of sustained ventricular tachycardia (VT). In this case, we mainly discuss the application of myocardial contrast echocardiography (MCE) in displaying myocardial fibrosis in patients with ARVC. CASE PRESENTATION: A 43-year-old male experienced three episodes of unexplained VT over an eight-year period, accompanied by symptoms of chest discomfort, palpitations and dizziness. Coronary angiography revealed no significant coronary stenosis. The electrocardiogram (ECG) results indicated characteristic epsilon waves in right precordial leads, and subsequent echocardiography identified right ventricular enlargement and right ventricular systolic dysfunction. MCE further disclosed regional myocardial ischemia at the epicardium of the left ventricular apex. Ultimately, cardiovascular magnetic resonance imaging (CMR) corroborated the ARVC diagnosis, highlighting linear intensification in the right ventricle during the delayed enhancement. CONCLUSION: Prompt identification of ARVC is crucial for timely intervention and management. MCE may offer an effective and valuable technique for the detection of myocardial involvement in ARVC patient.