Nucleotide-Binding Oligomerization Domain-Like Receptor 3 Deficiency Attenuated Isoproterenol-Induced Cardiac Fibrosis via Reactive Oxygen Species/High Mobility Group Box 1 Protein Axis

A comprehensive review on the pharmacological role of gut microbiome in neurodegenerative disorders: potential therapeutic targets

Neurological disorders, including Alzheimer and Parkinson's, pose significant challenges to public health due to their complex etiologies and limited treatment options. Recent advances in research have highlighted the intricate bidirectional communication between the gut microbiome and the central nervous system (CNS), revealing a potential therapeutic avenue for neurological disorders. Thus, this review aims to summarize the current understanding of the pharmacological role of gut microbiome in neurological disorders. Mounting evidence suggests that the gut microbiome plays a crucial role in modulating CNS function through various mechanisms, including the production of neurotransmitters, neuroactive metabolites, and immune system modulation. Dysbiosis, characterized by alterations in gut microbial composition and function, has been observed in many neurological disorders, indicating a potential causative or contributory role. Pharmacological interventions targeting the gut microbiome have emerged as promising therapeutic strategies for neurological disorders. Probiotics, prebiotics, antibiotics, and microbial metabolite-based interventions have shown beneficial effects in animal models and some human studies. These interventions aim to restore microbial homeostasis, enhance microbial diversity, and promote the production of beneficial metabolites. However, several challenges remain, including the need for standardized protocols, identification of specific microbial signatures associated with different neurological disorders, and understanding the precise mechanisms underlying gut-brain communication. Further research is necessary to unravel the intricate interactions between the gut microbiome and the CNS and to develop targeted pharmacological interventions for neurological disorders.

Fn-HMGB1 Adsorption Behavior Initiates Early Immune Recognition and Subsequent Osteoinduction of Biomaterials

Implantable biomaterials are widely used in bone tissue engineering, but little is still known about how they initiate early immune recognition and the initial dynamics. Herein, the early immune recognition and subsequent osteoinduction of biphasic calcium phosphate (BCP) after implantation to the protein adsorption behavior is attributed. By liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis, the biomaterial-related molecular patterns (BAMPs) formed after BCP implantation are mapped, dominated by the highly expressed extracellular matrix protein fibronectin (Fn) and the high mobility group box 1 (HMGB1). Molecular dynamics simulations show that Fn has the ability to bind more readily to the BCP surface than HMGB1. The preferential binding of Fn provides a higher adsorption energy for HMGB1. Furthermore, multiple hydrogen bonding sites between HMGB1 and Fn are demonstrated using a molecular docking approach. Ultimately, the formation of BAMPs through HMGB1 antagonist glycyrrhizic acid (GA), resulting in impaired immune recognition of myeloid differentiation factor 88 (MYD88) mediated dendritic cells (DCs) and macrophages (Mφs), as well as failed osteoinduction processes is obstructed. This study introduces a mechanism for early immune recognition of implant materials based on protein adsorption, providing perspectives for future design and application of tissue engineering materials.

PRDM16 exerts critical role in myocardial metabolism and energetics in type 2 diabetes induced cardiomyopathy

BACKGROUND

The prevalence of type 2 diabetes mellitus (T2DM) has increased over the past decades. Diabetic cardiomyopathy (DCM) is the leading cause of death in T2DM patients, however, the mechanism underlying DCM remains largely unknown. Here, we aimed to investigate the role of cardiac PR-domain containing 16 (PRDM16) in T2DM.

METHODS

We modeled mice with cardiac-specific deletion of Prdm16 by crossing the floxed Prdm16 mouse model with the cardiomyocyte-specific Cre transgenic mouse. The mice were continuously fed a chow diet or high-fat diet combining with streptozotocin (STZ) for 24 weeks to establish a T2DM model. DB/DB and adequate control mice were given a single intravenous injection of adeno-associated virus 9 (AAV9) carrying cardiac troponin T (cTnT) promoter-driven small hairpin RNA targeting PRDM16 (AAV9-cTnT-shPRDM16) from the retro-orbital venous plexus to knockout Prdm16 in the myocardium. There were at least 12 mice in each group. Mitochondrial morphology and function were detected using transmission electron microscopy, western blot determining the protein level of mitochondrial respiratory chain complex, mitotracker staining and Seahorse XF Cell Mito Stress Test Kit. Untargeted metabolomics analysis and RNA-seq analysis were performed to determine the molecular and metabolic changes associated with Prdm16 deficiency. BODIPY and TUNEL staining were used to detect lipid uptake and apoptosis. Co-immunoprecipitation and ChIP assays were conducted to examine the potential underlying mechanism.

RESULTS

Prdm16 cardiac-specific deficiency accelerated cardiomyopathy and worsened cardiac dysfunction in mice with T2DM, aggravating mitochondrial dysfunction and apoptosis both in vivo and in vitro, while PRDM16 overexpression the deterioration. Prdm16 deficiency also caused cardiac lipid accumulation resulting in metabolic and molecular alterations in T2DM mouse models. Co-IP and luciferase assays confirmed that PRDM16 targeted and regulated the transcriptional activity, expression and interaction of PPAR-α and PGC-1α, while the overexpression of PPAR-α and PGC-1α reversed Prdm16 deficiency-induced cellular dysfunction in T2DM model. Moreover, PRDM16 regulated PPAR-α and PGC-1α and affected mitochondrial function by mainly depending on epigenetic regulation of H3K4me3.

CONCLUSIONS

These findings suggest that PRDM16 exerted its protective role in myocardial lipid metabolism and mitochondrial function in T2DM in a histone lysine methyltransferase activity-dependent manner by regulating PPAR-α and PGC-1α.

Trastuzumab potentiates doxorubicin-induced cardiotoxicity via activating the NLRP3 inflammasome in vivo and in vitro

Trastuzumab (Tra), the first humanized monoclonal antibody that targets human epidermal growth factor receptor 2 (HER2), is commonly used alongside doxorubicin (Dox) as a combination therapy in HER2-positive breast cancer. Unfortunately, this leads to a more severe cardiotoxicity than Dox alone. NLRP3 inflammasome is known to be involved in Dox-induced cardiotoxicity and multiple cardiovascular diseases. However, whether the NLRP3 inflammasome contributes to the synergistic cardiotoxicity of Tra has not been elucidated. In this study, primary neonatal rat cardiomyocyte (PNRC), H9c2 cells and mice were treated with Dox (15 mg/kg in mice or 1μM in cardiomyocyte) or Tra (15.75 mg/kg in mice or 1μM in cardiomyocyte), or Dox combined Tra as cardiotoxicity models to investigate this question. Our results demonstrated that Tra significantly potentiated Dox-induced cardiomyocyte apoptosis and cardiac dysfunction. These were accompanied by the increased expressions of NLRP3 inflammasome components (NLRP3, ASC and cleaved caspase-1), the secretion of IL-β and the pronounced production of ROS. Inhibiting the activation of NLRP3 inflammasome by NLRP3 silencing significantly reduced cell apoptosis and ROS production in Dox combined Tra-treated PNRC. Compared with the wild type mice, the systolic dysfunction, myocardial hypertrophy, cardiomyocyte apoptosis and oxidative stress induced by Dox combined Tra were alleviated in NLRP3 gene knockout mice. Our data revealed that the co-activation of NLRP3 inflammasome by Tra promoted the inflammation, oxidative stress and cardiomyocytes apoptosis in Dox combined Tra-induced cardiotoxicity model both in vivo and in vitro. Our results suggest that NLRP3 inhibition is a promising cardioprotective strategy in Dox/Tra combination therapy.

Hepatic HRC induces hepatocyte pyroptosis and HSCs activation via NLRP3/caspase-1 pathway

The histidine-rich calcium-binding protein (HRC) is a regulator of Ca2 + homeostasis and it plays a significant role in liver fibrosis. Pyroptosis, a specific inflammatory cell death, can lead to hepatic stellate cells (HSCs) activation and liver fibrosis. However, the role of HRC in pyroptosis has not been explored. In this study, we demonstrated that HRC, mainly located in the hepatocyte, was over expressed in fibrotic liver tissues. We further found that enforced expression of HRC in hepatocytes induced pyroptosis and HMGB1 release, and subsequently led to HSCs activation by NLRP3/caspase-1 pathway. In addition, the proliferation and migration of HSCs were also enhanced by HRC overexpression in hepatocytes. Furthermore, NLRP3 inhibitor MCC950 and caspase-1 inhibitor VX-765 alleviated hepatic HRC-mediated hepatocytes pyroptosis and HSCs activation. This study demonstrated that hepatic HRC promoted HSCs activation by inducing hepatocyte pyroptosis, which suggests that HRC may be a promising therapeutic target to prevent liver fibrosis.

Novel Techniques Targeting Fibroblasts after Ischemic Heart Injury

The great plasticity of cardiac fibroblasts allows them to respond quickly to myocardial injury and to contribute to the subsequent cardiac remodeling. Being the most abundant cell type (in numbers) in the heart, and a key participant in the several phases of tissue healing, the cardiac fibroblast is an excellent target for treating cardiac diseases. The development of cardiac fibroblast-specific approaches have, however, been difficult due to the lack of cellular specific markers. The development of genetic lineage tracing tools and Cre-recombinant transgenics has led to a huge acceleration in cardiac fibroblast research. Additionally, the use of novel targeted delivery approaches like nanoparticles and modified adenoviruses, has allowed researchers to define the developmental origin of cardiac fibroblasts, elucidate their differentiation pathways, and functional mechanisms in cardiac injury and disease. In this review, we will first characterize the roles of fibroblasts in the different stages of cardiac repair and then examine novel techniques targeting fibroblasts post-ischemic heart injury.

Epigenetic Repression of Chloride Channel Accessory 2 Transcription in Cardiac Fibroblast: Implication in Cardiac Fibrosis

Cardiac fibrosis is a key pathophysiological process that contributes to heart failure. Cardiac resident fibroblasts, exposed to various stimuli, are able to trans-differentiate into myofibroblasts and mediate the pro-fibrogenic response in the heart. The present study aims to investigate the mechanism whereby transcription of chloride channel accessory 2 (Clca2) is regulated in cardiac fibroblast and its potential implication in fibroblast-myofibroblast transition (FMyT). We report that Clca2 expression was down-regulated in activated cardiac fibroblasts (myofibroblasts) compared to quiescent cardiac fibroblasts in two different animal models of cardiac fibrosis. Clca2 expression was also down-regulated by TGF-β, a potent inducer of FMyT. TGF-β repressed Clca2 expression at the transcriptional level likely via the E-box element between -516 and -224 of the Clca2 promoter. Further analysis revealed that Twist1 bound directly to the E-box element whereas Twist1 depletion abrogated TGF-β induced Clca2 trans-repression. Twist1-mediated Clca2 repression was accompanied by erasure of histone H3/H4 acetylation from the Clca2 promoter. Mechanistically Twist1 interacted with HDAC1 and recruited HDAC1 to the Clca2 promoter to repress Clca2 transcription. Finally, it was observed that Clca2 over-expression attenuated whereas Clca2 knockdown enhanced FMyT. In conclusion, our data demonstrate that a Twist1-HDAC1 complex represses Clca2 transcription in cardiac fibroblasts, which may contribute to FMyT and cardiac fibrosis.

High-Mobility Group A1 Promotes Cardiac Fibrosis by Upregulating FOXO1 in Fibroblasts

High-mobility group A1 (HMGA1) acts as a transcription factor in several cardiovascular diseases. However, the implications of HMGA1 in cardiac fibrosis remain unknown. Here, we investigated the impact of HMGA1 on cardiac fibrosis. A mouse cardiac fibrosis model was constructed via subcutaneous injection of isoproterenol (ISO) or angiotensin II (Ang II) infusion. Adult mouse cardiac fibroblasts (CFs) were isolated and cultured. CFs were stimulated with transforming growth factor-β1 (TGF-β1) for 24 h. As a result, HMGA1 was upregulated in fibrotic hearts, as well as TGF-β-stimulated CFs. Overexpression of HMGA1 in CFs aggravated TGF-β1-induced cell activation, proliferation, and collagen synthesis. Overexpression of HMGA1 in fibroblasts, by an adeno-associated virus 9 dilution system with a periostin promoter, accelerated cardiac fibrosis and cardiac dysfunction. Moreover, HMGA1 knockdown in CFs inhibited TGF-β1-induced cell activation, proliferation, and collagen synthesis. Mechanistically, we found that HMGA1 increased the transcription of FOXO1. The FOXO1 inhibitor AS1842856 counteracted the adverse effects of HMGA1 overexpression in vitro. HMGA1 silencing in mouse hearts alleviated Ang II-induced cardiac fibrosis and dysfunction. However, FOXO1 knockdown in mouse hearts abolished the deteriorating effects of HMGA1 overexpression in mice. Collectively, our data demonstrated that HMGA1 plays a critical role in the development of cardiac fibrosis by regulating FOXO1 transcription.