TDP43 Exacerbates Atherosclerosis Progression by Promoting Inflammation and Lipid Uptake of Macrophages

Therapeutic Targeting of Pattern Recognition Receptors to Modulate Inflammation in Atherosclerosis

Atherosclerosis (AS), a potentially fatal cardiovascular disease (CVD), is a chronic inflammatory condition. The disease's onset and progression are influenced by inflammatory and immunological mechanisms. The innate immune pathways are essential in the progression of AS, as they are responsible for detecting first danger signals and causing long-term changes in immune cells. The innate immune system possesses distinct receptors known as pattern recognition receptors (PRRs) which can identify both pathogen-associated molecular patterns and danger-associated molecular signals. Activation of PRRs initiates the inflammatory response in various physiological systems, such as the cardiovascular system. This review specifically examines the contribution of the innate immune response and PRRs to the formation and advancement of AS. Studying the role of these particular receptors in AS would enhance our understanding of the development of AS and offer novel approaches for directly improving the inflammatory response associated with it.

Mechanisms of mitochondrial damage-associated molecular patterns associated with inflammatory response in cardiovascular diseases

Cardiovascular diseases (CVDs) continue to be a substantial global healthcare burden despite considerable progress in therapies. The inflammatory response during the progression of CVD has attracted considerable attention. Mitochondria serve as the principal energy source for the heart. In cardiovascular illnesses, mitochondrial homeostasis is disrupted, accompanied by structural and functional impairments. During mitochondrial stress or injury, mitochondrial damage-associated molecular patterns (mtDAMPs), such as mitochondrial DNA, cardiolipin, N-formyl peptide, and adenosine triphosphate, are released to activate pattern recognition receptors and trigger immunological responses. Inflammatory responses mediated by mtDAMPs substantially contribute to the pathophysiology of cardiovascular illnesses. In this review, we discuss the molecular mechanisms by which different mtDAMPs control the inflammatory response, address the pathological consequences of mtDAMPs in inducing or exacerbating the inflammatory response in CVDs, and summarize potential therapeutic targets in relevant experimental studies. Preventing or reducing mtDAMP release may play a role in CVD progression by alleviating the inflammatory response.

Inflammation in atherosclerosis: pathophysiology and mechanisms

Atherosclerosis imposes a heavy burden on cardiovascular health due to its indispensable role in the pathogenesis of cardiovascular disease (CVD) such as coronary artery disease and heart failure. Ample clinical and experimental evidence has corroborated the vital role of inflammation in the pathophysiology of atherosclerosis. Hence, the demand for preclinical research into atherosclerotic inflammation is on the horizon. Indeed, the acquisition of an in-depth knowledge of the molecular and cellular mechanisms of inflammation in atherosclerosis should allow us to identify novel therapeutic targets with translational merits. In this review, we aimed to critically discuss and speculate on the recently identified molecular and cellular mechanisms of inflammation in atherosclerosis. Moreover, we delineated various signaling cascades and proinflammatory responses in macrophages and other leukocytes that promote plaque inflammation and atherosclerosis. In the end, we highlighted potential therapeutic targets, the pros and cons of current interventions, as well as anti-inflammatory and atheroprotective mechanisms.

The cGAS-STING/PERK-eIF2α: Individual or Potentially Collaborative Signaling Transduction in Cardiovascular Diseases

Over the past several decades, a canonical pathway called the cyclic GMP-AMP (cGAMP) synthase (cGAS)-stimulator of interferon genes (STING) mediating type I interferon (IFN) release via TANK-binding kinase 1(TBK1) / IFN regulatory factor 3 (IRF3) pathway has been widely investigated and characterized. Unexpectedly, recent studies show that the cGAS-STING noncanonically activates the protein kinase RNA-like ER kinase (PERK)-eukaryotic initiation factor 2α (eIF2α), an essential branch of unfolded protein response (UPR), even before the activation of the TBK1/IRF3 signaling. Additionally, we found that the PERK could regulate the STING signaling besides being modulated by upstream cGAS-STING. However, earlier evidence solely focused on the unidirectional regulation of STING and PERK, lacking their functional crosstalk. Hence, we postulate that there is a complex relationship between the cGAS-STING and PERK-eIF2α pathways and that, through convergent downstream signaling, they may collaboratively contribute to the pathophysiology of cardiovascular diseases (CVDs) via the cGAS-STING/PERK-eIF2α signaling axis. This study provides a novel pathway for the development of CVDs and paves the foundation for potential therapeutic targets for CVDs.

Role of cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes pathway in diabetes and its complications

Diabetes mellitus (DM) is one of the major causes of mortality worldwide, with inflammation being an important factor in its onset and development. This review summarizes the specific mechanisms of the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway in mediating inflammatory responses. Furthermore, it comprehensively presents related research progress and the subsequent involvement of this pathway in the pathogenesis of early-stage DM, diabetic gastroenteropathy, diabetic cardiomyopathy, non-alcoholic fatty liver disease, and other complications. Additionally, the role of cGAS-STING in autonomic dysfunction and intestinal dysregulation, which can lead to digestive complications, has been discussed. Altogether, this study provides a comprehensive analysis of the research advances regarding the cGAS-STING pathway-targeted therapeutic agents and the prospects for their application in the precision treatment of DM.

Metabolic regulation of the immune system in health and diseases: mechanisms and interventions

Metabolism, including glycolysis, oxidative phosphorylation, fatty acid oxidation, and other metabolic pathways, impacts the phenotypes and functions of immune cells. The metabolic regulation of the immune system is important in the pathogenesis and progression of numerous diseases, such as cancers, autoimmune diseases and metabolic diseases. The concept of immunometabolism was introduced over a decade ago to elucidate the intricate interplay between metabolism and immunity. The definition of immunometabolism has expanded from chronic low-grade inflammation in metabolic diseases to metabolic reprogramming of immune cells in various diseases. With immunometabolism being proposed and developed, the metabolic regulation of the immune system can be gradually summarized and becomes more and more clearer. In the context of many diseases including cancer, autoimmune diseases, metabolic diseases, and many other disease, metabolic reprogramming occurs in immune cells inducing proinflammatory or anti-inflammatory effects. The phenotypic and functional changes of immune cells caused by metabolic regulation further affect and development of diseases. Based on experimental results, targeting cellular metabolism of immune cells becomes a promising therapy. In this review, we focus on immune cells to introduce their metabolic pathways and metabolic reprogramming, and summarize how these metabolic pathways affect immune effects in the context of diseases. We thoroughly explore targets and treatments based on immunometabolism in existing studies. The challenges of translating experimental results into clinical applications in the field of immunometabolism are also summarized. We believe that a better understanding of immune regulation in health and diseases will improve the management of most diseases.

The effects of cGAS-STING inhibition in liver disease, kidney disease, and cellular senescence

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway is one of the fundamental mechanisms of the body's defense, which responds to the abnormal presence of double-stranded DNA in the cytoplasm to establish an effective natural immune response. In addition to detecting microbial infections, the cGAS pathway may be triggered by any cytoplasmic DNA, which is absent from the normal cytoplasm, and only conditions such as senescence and mitochondrial stress can lead to its leakage and cause sterile inflammation. A growing body of research has shown that the cGAS-STING pathway is strongly associated with sterile inflammation. In this study, we reviewed the regulatory mechanisms and biological functions of the cGAS-STING pathway through its involvement in aseptic inflammation in liver disease, kidney disease, and cellular senescence.

Combined Treatment with Bojungikgi-tang (Buzhong Yiqi Decoction) and Riluzole Attenuates Cell Death in TDP-43-Expressing Cells

OBJECTIVE

To examine the effect of combined treatment with Bojungikgi-tang (BJIGT, Buzhong Yiqi Decoction) and riluzole (RZ) in transactive response DNA-binding protein 43 (TDP-43) stress granule (SG) cells, a amyotrophic lateral sclerosis (ALS) cell line using transcriptomic and molecular techniques.

METHODS

TDP-43 SG cells were pretreated with BJIGT (100 µg/mL), RZ (50 µmol/L), and combined BJIGT (100 µg/mL)/RZ (50 µmol/L) for 6 h before treatment with lipopolysaccharide (LPS, 200 µmol/L). Cell viability assay was performed to elucidate cell toxicity in TDP-43 SC cells using a cell-counting kit-8 (CCK8) assay kit. The expression levels of cell death-related proteins, including Bax, caspase 1, cleaved caspase 3 and DJ1 in TDP-43 SG cells were examined by Western blot analysis. The autophagy-related proteins, including pmTOR/mTOR, LC3b, P62, ATG7 and Bcl-2-associated athanogene 3 (Bag3) were investigated using immunofluorescence and immunoblotting assays.

RESULTS

Cell viability assay and Western blot analysis showed that combined treatment with BJIGT and RZ suppressed LPS-induced cell death and expression of cell death-related proteins, including Bax, caspase 1, and DJ1 (P<0.05 or P<0.01). Immunofluorescence and immunoblotting assays showed that combined treatment with BJIGT and RZ reduced LPS-induced formation of TDP-43 aggregates and regulated autophagy-related protein levels, including p62, light chain 3b, Bag3, and ATG7, in TDP-43-expressing cells (P<0.05 or P<0.01).

CONCLUSION

The combined treatment of BJIGT and RZ might reduce inflammation and regulate autophagy dysfunction in TDP-43-induced ALS.

Investigating Vitamin D-Binding Protein's Role in Childhood Health and Development

Vitamin D-binding protein (DBP), also known as Gc-globulin, is a protein that affects several physiological processes, including the transport and regulation of vitamin D metabolites. Genetic polymorphisms in the DBP gene have a significant impact on vitamin D levels and may have implications for disease risk. DBP polymorphisms are linked to differential immune responses, which could influence the onset of juvenile diseases. This narrative review examines the various roles of DBP, with a focus on bone health, immunological regulation, and lipid metabolism in children. Chronic disorders affected by DBP polymorphisms include bone abnormalities, autoimmune diseases, cardiovascular issues, childhood asthma, allergies, cystic fibrosis, acute liver failure, celiac disease, inflammatory bowel disease, and chronic kidney disease. Future research should focus on identifying the processes that underpin the many roles that DBP plays and developing customized therapeutics to improve health outcomes in the juvenile population.

cGAS-STING signaling in cardiovascular diseases

Sterile inflammation, characterized by a persistent chronic inflammatory state, significantly contributes to the progression of various diseases such as autoimmune, metabolic, neurodegenerative, and cardiovascular disorders. Recent evidence has increasingly highlighted the intricate connection between inflammatory responses and cardiovascular diseases, underscoring the pivotal role of the Stimulator of Interferon Genes (STING). STING is crucial for the secretion of type I interferon (IFN) and proinflammatory cytokines in response to cytosolic nucleic acids, playing a vital role in the innate immune system. Specifically, research has underscored the STING pathway involvement in unregulated inflammations, where its aberrant activation leads to a surge in inflammatory events, enhanced IFN I responses, and cell death. The primary pathway triggering STING activation is the cyclic GMP-AMP synthase (cGAS) pathway. This review delves into recent findings on STING and the cGAS-STING pathways, focusing on their regulatory mechanisms and impact on cardiovascular diseases. It also discusses the latest advancements in identifying antagonists targeting cGAS and STING, and concludes by assessing the potential of cGAS or STING inhibitors as treatments for cardiovascular diseases.

Transcriptome-wide N6-methyladenosine methylation profile of atherosclerosis in mice

BACKGROUND

Atherosclerosis (AS) is a critical pathological event during the progression of cardiovascular diseases. It exhibits fibrofatty lesions on the arterial wall and lacks effective treatment. N6-methyladenosine (m6A) is the most common modification of eukaryotic RNA and plays an important role in regulating the development and progression of cardiovascular diseases. However, the role of m6A modification in AS remains largely unknown. Therefore, in this study, we explored the transcriptome distribution of m6A modification in AS and its potential mechanism.

METHODS

Methylation Quantification Kit was used to detect the global m6A levels in the aorta of AS mice. Western blot was used to analyze the protein level of methyltransferases. Methylated RNA immunoprecipitation with next-generation sequencing (MeRIP-seq) and RNA sequencing (RNA-seq) were used to obtain the first transcriptome range analysis of the m6A methylene map in the aorta of AS mice, followed by bioinformatics analysis. qRT-PCR and MeRIP-qRT-PCR were used to measure the mRNA and m6A levels in target genes.

RESULTS

The global m6A and protein levels of methyltransferase METTL3 were significantly increased in the aorta of AS mice. However, the protein level of demethylase ALKBH5 was significantly decreased. Through MeRIP-seq, we obtained m6A methylation maps in AS and control mice. In total, 26,918 m6A peaks associated with 13,744 genes were detected in AS group, whereas 26,157 m6A peaks associated with 13,283 genes were detected in the control group. Peaks mainly appeared in the coding sequence (CDS) regions close to the stop codon with the RRACH motif. Moreover, functional enrichment analysis demonstrated that m6A-containing genes were significantly enriched in AS-relevant pathways. Interestingly, a negative correlation between m6A methylation abundance and gene expression level was found through the integrated analysis of MeRIP-seq and RNA-seq data. Among the m6A-modified genes, a hypo-methylated but up-regulated (hypo-up) gene Fabp5 may be a potential biomarker of AS.

CONCLUSIONS

Our study provides transcriptome-wide m6A methylation for the first time to determine the association between m6A modification and AS progression. Our study lays a foundation for further exploring the pathogenesis of AS and provides a new direction for the treatment of AS.

DHX9 Strengthens Atherosclerosis Progression By Promoting Inflammation in Macrophages

Atherosclerosis (AS) is the main cause of cerebrovascular diseases, and macrophages play important roles in atherosclerosis. DExH-Box helicase 9 (DHX9), as a member of DExD/H-box RNA helicase superfamily II, is identified as an autoantigen in the sera of systemic lupus erythematosus patients to trigger inflammation. The aim of this study was to investigate whether DHX9 is involved in AS development, especially in macrophages-mediated-inflammatory responses. We find that DHX9 expression is significantly increased in oxLDL or interferon-γ-treated macrophages and peripheral blood mononuclear cells (PBMCs) from patients with coronary artery disease (CAD). Knockdown of DHX9 inhibits lipid uptake and pro-inflammatory factors expression in macrophages, and ameliorates TNF-α-mediated monocyte adhesion capacity. Furthermore, we find that oxLDL stimulation promotes DHX9 interaction with p65 in macrophages, and further enhances the transcriptional activity of DHX9-p65-RNA Polymerase II complex to produce inflammatory factors. Moreover, using ApoE -/- mice fed with western diet to establish AS model, we find that knockdown of DHX9 mediated by adeno-associated virus-Sh-DHX9 through tail vein injection evidently alleviates AS progression in vivo. Finally, we also find that knockdown of DHX9 inhibits p65 activation, inflammatory factors expression, and the transcriptional activity of p65-RNA Polymerase II complex in PBMCs from patients with CAD. Overall, these results indicate that DHX9 promotes AS progression by enhancing inflammation in macrophages, and suggest DHX9 as a potential target for developing therapeutic drug.

Targeting PPARs for therapy of atherosclerosis: A review

Atherosclerosis, a chief pathogenic factor of cardiovascular disease, is associated with many factors including inflammation, dyslipidemia, and oxidative stress. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and are widely expressed with tissue- and cell-specificity. They control multiple genes that are involved in lipid metabolism, inflammatory response, and redox homeostasis. Given the diverse biological functions of PPARs, they have been extensively studied since their discovery in 1990s. Although controversies exist, accumulating evidence have demonstrated that PPAR activation attenuates atherosclerosis. Recent advances are valuable for understanding the mechanisms of action of PPAR activation. This article reviews the recent findings, mainly from the year of 2018 to present, including endogenous molecules in regulation of PPARs, roles of PPARs in atherosclerosis by focusing on lipid metabolism, inflammation, and oxidative stress, and synthesized PPAR modulators. This article provides information valuable for researchers in the field of basic cardiovascular research, for pharmacologists that are interested in developing novel PPAR agonists and antagonists with lower side effects as well as for clinicians.

Tetrandrine alleviates atherosclerosis via inhibition of STING-TBK1 pathway and inflammation in macrophages

Atherosclerosis (AS) is a chronic inflammatory disease. Recent studies have showed that stimulator of interferon genes (STING), an important protein in innate immunity, mediates pro-inflammatory activation of macrophages in the development of AS. Tetrandrine (TET) is a natural bisbenzylisoquinoline alkaloid isolated from Stepania tetrandra and possesses anti-inflammatory activities, with unknown effects and mechanisms in AS. In this study, we explored the anti-atherosclerotic effects of TET and investigated the underlying mechanisms. Mouse primary peritoneal macrophages (MPMs) are challenged with cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) or oxidized LDL (oxLDL). We found that pretreatment with TET dose-dependently inhibited cGAMP- or oxLDL-induced STING/ TANK-binding kinase 1 (TBK1) signaling, then suppressing nuclear factor kappa-B (NF-κB) activation and pro-inflammatory factor expression in MPMs. ApoE^-/- mice were fed a high-fat diet (HFD) to develop an atherosclerotic phenotype. Administration of TET at 20 mg/kg/day significantly reduced HFD-induced atherosclerotic plaques, accompanied with decreased macrophage infiltration, inflammatory cytokine production, fibrosis, and STING/TBK1 activation in aortic plaque lesions. In summary, we demonstrate that TET inhibits STING/TBK1/NF-κB signaling pathway to reduce inflammation in oxLDL-challenged macrophages and alleviate atherosclerosis in HFD-fed ApoE^-/- mice. These findings proved that TET could be a potential therapeutic candidate for the treatment of atherosclerosis-related diseases.

The Role of cGAS-STING in Age-Related Diseases from Mechanisms to Therapies

With aging, the incidence of age-related diseases increases. Hence, age-related diseases are inevitable. However, the mechanisms by which aging leads to the onset and progression of age-related diseases remain unclear. It has been reported that inflammation is closely associated with age-related diseases and that the cGAS-STING signaling pathway, which can sense the aberrant presence of cytosolic DNA during aging and induce an inflammatory response, is an important mediator of inflammation in age-related diseases. With a better understanding of the structure and molecular biology of the cGAS-STING signaling axis, numerous selective inhibitors and agonists targeting the cGAS-STING pathway in human age-related diseases have been developed to modulate inflammatory responses. Here, we provide a narrative review of the activity of the cGAS- STING pathway in age-related diseases and discuss its general mechanisms in the onset and progression of age-related diseases. In addition, we outline treatments targeting the cGAS-STING pathway, which may constitute a potential therapeutic alternative for age-related diseases.

cGAS-STING Pathway Performance in the Vulnerable Atherosclerotic Plaque

The important role of Ca2+ in pathogenic store-operated calcium entry (SOCE) is well-established. Among the proteins involved in the calcium signaling pathway, Stromal interacting molecule 1 (STIM1) is a critical endoplasmic reticulum transmembrane protein. STIM1 is activated by the depletion of calcium stores and then binds to another calcium protein, Orai1, to form a channel through which the extracellular Ca2+ can enter the cytoplasm to replenish the calcium store. Multiple studies have shown that increased STIM1 facilitates the aberrant proliferation and apoptosis of vascular smooth cells (VSMC) and macrophages which can promote the formation of rupture-prone plaque. Together with regulating the cytosolic Ca2+ concentration, STIM1 also activates STING through altered intracellular Ca2+ concentration, a critical pro-inflammatory molecule. The cGAS-STING pathway is linked with cellular proliferation and phenotypic conversion of VSMC and enhances the progression of atherosclerosis plaque. In summary, we conclude that STIM1/cGAS-STING is involved in the progression of AS and plaque vulnerability.

Link between sterile inflammation and cardiovascular diseases: Focus on cGAS-STING pathway in the pathogenesis and therapeutic prospect

Sterile inflammation characterized by unresolved chronic inflammation is well established to promote the progression of multiple autoimmune diseases, metabolic disorders, neurodegenerative diseases, and cardiovascular diseases, collectively termed as sterile inflammatory diseases. In recent years, substantial evidence has revealed that the inflammatory response is closely related to cardiovascular diseases. Cyclic guanosine monophosphate–adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway which is activated by cytoplasmic DNA promotes the activation of interferon regulatory factor 3 (IRF3) or nuclear factor-κB (NF-κB), thus leading to upregulation of the levels of inflammatory factors and interferons (IFNs). Therefore, studying the role of inflammation caused by cGAS-STING pathway in cardiovascular diseases could provide a new therapeutic target for cardiovascular diseases. This review focuses on that cGAS-STING-mediated inflammatory response in the progression of cardiovascular diseases and the prospects of cGAS or STING inhibitors for treatment of cardiovascular diseases.

Upregulation of Neogenin-1 by a CREB1-BAF47 Complex in Vascular Endothelial Cells is Implicated in Atherogenesis

Atherosclerosis is generally considered a human pathology of chronic inflammation, to which endothelial dysfunction plays an important role. Here we investigated the role of neogenin 1 (Neo-1) in oxidized low-density lipoprotein (oxLDL) induced endothelial dysfunction focusing on its transcriptional regulation. We report that Neo-1 expression was upregulated by oxLDL in both immortalized vascular endothelial cells and primary aortic endothelial cells. Neo-1 knockdown attenuated whereas Neo-1 over-expression enhanced oxLDL-induced leukocyte adhesion to endothelial cells. Neo-1 regulated endothelial-leukocyte interaction by modulating nuclear factor kappa B (NF-κB) activity to alter the expression of adhesion molecules. Neo-1 blockade with a blocking antibody ameliorated atherogenesis in Apoe^−/− mice fed a Western diet. Ingenuity pathway analysis combined with validation assays confirmed that cAMP response element binding protein 1 (CREB1) and Brg1-associated factor 47 (BAF47) mediated oxLDL induced Neo-1 upregulation. CREB1 interacted with BAF47 and recruited BAF47 to the proximal Neo-1 promoter leading to Neo-1 trans-activation. In conclusion, our data delineate a novel transcriptional mechanism underlying Neo-1 activation in vascular endothelial cells that might contribute to endothelial dysfunction and atherosclerosis.