Naringenin modulates the NO­cGMP­PKG signaling pathway by binding to AKT to enhance osteogenic differentiation in hPDLSCs.

Naringenin (NAR) is a prominent flavanone that has been recognized for its capacity to promote the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs). The present study aimed to explore how NAR promotes the osteogenic differentiation of hPDLSCs and to assess its efficacy in repairing alveolar bone defects. For this purpose, a protein­protein interaction network of NAR action was established by mRNA sequencing and network pharmacological analysis. Gene and protein expression levels were evaluated by reverse transcription­quantitative and western blotting. Alizarin red and alkaline phosphatase staining were also employed to observe the osteogenic capacity of hPDLSCs, and immunofluorescence was used to examine the co­localization of NAR molecular probes and AKT in cells. The repair of mandibular defects was assessed by micro­computed tomography (micro­CT), Masson staining and immunofluorescence. Additionally, computer simulation docking software was utilized to determine the binding affinity of NAR to the target protein, AKT. The results demonstrated that activation of the nitric oxide (NO)­cyclic guanosine monophosphate (cGMP)­protein kinase G (PKG) signaling pathway could promote the osteogenic differentiation of hPDLSCs. Inhibition of AKT, endothelial nitric oxide synthase and soluble guanylate cyclase individually attenuated the ability of NAR to promote the osteogenic differentiation of hPDLSCs. Micro­CT and Masson staining revealed that the NAR gavage group exhibited more new bone formation at the defect site. Immunofluorescence assays confirmed the upregulated expression of Runt­related transcription factor 2 and osteopontin in the NAR gavage group. In conclusion, the results of the present study suggested that NAR promotes the osteogenic differentiation of hPDLSCs by activating the NO­cGMP­PKG signaling pathway through its binding to AKT.

The Construction and Application of a New Screening Method for Phosphodiesterase Inhibitors.

Phosphodiesterases (PDEs), a superfamily of enzymes that hydrolyze cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), are recognized as a therapeutic target for various diseases. However, the current screening methods for PDE inhibitors usually experience problems due to complex operations and/or high costs, which are not conducive to drug development in respect of this target. In this study, a new method for screening PDE inhibitors based on GloSensor technology was successfully established and applied, resulting in the discovery of several novel compounds of different structural types with PDE inhibitory activity. Compared with traditional screening methods, this method is low-cost, capable of dynamically detecting changes in substrate concentration in live cells, and can be used to preliminarily determine the type of PDEs affected by the detected active compounds, making it more suitable for high-throughput screening for PDE inhibitors.

Safety, tolerability, pharmacokinetics, and pharmacodynamics of BI 685509, a soluble guanylyl cyclase activator, in healthy volunteers: Results from two randomized controlled trials.

This study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of BI 685509 after oral single rising doses (SRDs) or multiple rising doses (MRDs) in healthy volunteers. In the SRD trial (NCT02694354; February 29, 2016), within each of the three dose groups (DGs), six subjects received BI 685509 (1.0, 2.5, or 5.0 mg) and two received placebo (N = 24). In the MRD trial (NCT03116906; April 17, 2017), within each of the five DGs, nine subjects received BI 685509 (uptitrated to 1 mg once daily [qd; DG1], 2.5 mg twice daily [DG2], 5.0 mg qd [DG3]; 3.0 mg three times daily [tid; DG4] or 4.0 mg tid [DG5]) and three received placebo, for 14-17 days (N = 60). In the SRD trial, 7/24 subjects (29.2%) had ≥ 1 adverse event (AE), most frequently orthostatic dysregulation (n = 4). In the MRD trial, 26/45 subjects (57.8%) receiving BI 685509 had ≥ 1 AE, most frequently orthostatic dysregulation and fatigue (each n = 12). Tolerance development led to a marked decrease in orthostatic dysregulation events (DG3). BI 685509 was rapidly absorbed after oral administration, and exposure increased in a dose-proportional manner after single doses. Multiple dosing resulted in near-dose-proportional increase in exposure and limited accumulation. BI 685509 pharmacokinetics appeared linear with time; steady state occurred 3-5 days after each multiple-dosing period. Increased plasma cyclic guanosine monophosphate and decreased blood pressure followed by a compensatory increase in heart rate indicated target engagement. BI 685509 was generally well tolerated; orthostatic dysregulation may be appropriately countered by careful uptitration.

Antiplatelet Effects of Flavonoid Aglycones Are Mediated by Activation of Cyclic Nucleotide-Dependent Protein Kinases.

Flavonoid aglycones are secondary plant metabolites that exhibit a broad spectrum of pharmacological activities, including anti-inflammatory, antioxidant, anticancer, and antiplatelet effects. However, the precise molecular mechanisms underlying their inhibitory effect on platelet activation remain poorly understood. In this study, we applied flow cytometry to analyze the effects of six flavonoid aglycones (luteolin, myricetin, quercetin, eriodictyol, kaempferol, and apigenin) on platelet activation, phosphatidylserine externalization, formation of reactive oxygen species, and intracellular esterase activity. We found that these compounds significantly inhibit thrombin-induced platelet activation and decrease formation of reactive oxygen species in activated platelets. The tested aglycones did not affect platelet viability, apoptosis induction, or procoagulant platelet formation. Notably, luteolin, myricetin, quercetin, and apigenin increased thrombin-induced thromboxane synthase activity, which was analyzed by a spectrofluorimetric method. Our results obtained from Western blot analysis and liquid chromatography-tandem mass spectrometry demonstrated that the antiplatelet properties of the studied phytochemicals are mediated by activation of cyclic nucleotide-dependent signaling pathways. Specifically, we established by using Förster resonance energy transfer that the molecular mechanisms are, at least partly, associated with the inhibition of phosphodiesterases 2 and/or 5. These findings underscore the therapeutic potential of flavonoid aglycones for clinical application as antiplatelet agents.

The Combination of Oolonghomobisflavan B and Diallyl Disulfide Induces Apoptotic Cell Death via 67-kDa Laminin Receptor/Cyclic Guanosine Monophosphate in Acute Myeloid Leukemia Cells.

Diallyl disulfide (DADS) is a well-known principal functional component derived from garlic (Allium sativum) that has various health benefits. Previously, we identified a 67-kDa laminin receptor, a receptor for oolong tea polyphenol oolonghomobisflavan B (OHBFB). However, its molecular mechanisms still remain to be elucidated. Here, we show that DADS synergistically enhanced the effect of the oolong tea polyphenol oolonghomobisflavan B (OHBFB), which induces apoptosis in acute myeloid leukemia (AML) cancer cells without affecting normal human peripheral blood mononuclear cells (PBMCs). The underlying mechanism of OHBFB-induced anti-AML effects involves the upregulation of the 67-kDa laminin receptor/endothelial nitric oxide synthase/cyclic guanosine monophosphate (cGMP)/protein kinase c delta (PKCδ)/acid sphingomyelinase (ASM)/cleaved caspase-3 signaling pathway. In conclusion, we show that the combination of OHBFB and DADS synergistically induced apoptotic cell death in AML cells through activation of 67LR/cGMP/PKCδ/ASM signaling pathway. Moreover, in this mechanism, we demonstrate DADS may reduce the enzyme activity of phosphodiesterase, which is a negative regulator of cGMP that potentiates OHBFB-induced AML apoptotic cell death without affecting normal PBMCs.

MANP in Hypertension With Metabolic Syndrome: Proof-of-Concept Study of Natriuretic Peptide-Based Therapy for Cardiometabolic Disease.

Hypertension and metabolic syndrome frequently coexist to increase the risk for adverse cardiometabolic outcomes. To date, no drug has been proven to be effective in treating hypertension with metabolic syndrome. M-atrial natriuretic peptide is a novel atrial natriuretic peptide analog that activates the particulate guanylyl cyclase A receptor. This study conducted a double-blind, placebo-controlled trial in 22 patients and demonstrated that a single subcutaneous injection of M-atrial natriuretic peptide was safe, well-tolerated, and exerted pleiotropic properties including blood pressure-lowering, lipolytic, and insulin resistance-improving effects. (MANP in Hypertension and Metabolic Syndrome [MANP-HTN-MS]; NCT03781739).

Role of the NO-GC/cGMP signaling pathway in platelet biomechanics.

Cyclic guanosine monophosphate (cGMP) is a second messenger produced by the NO-sensitive guanylyl cyclase (NO-GC). The NO-GC/cGMP pathway in platelets has been extensively studied. However, its role in regulating the biomechanical properties of platelets has not yet been addressed and remains unknown. We therefore investigated the stiffness of living platelets after treatment with the NO-GC stimulator riociguat or the NO-GC activator cinaciguat using scanning ion conductance microscopy (SICM). Stimulation of human and murine platelets with cGMP-modulating drugs decreased cellular stiffness and downregulated P-selectin, a marker for platelet activation. We also quantified changes in platelet shape using deep learning-based platelet morphometry, finding that platelets become more circular upon treatment with cGMP-modulating drugs. To test for clinical applicability of NO-GC stimulators in the context of increased thrombogenicity risk, we investigated the effect of riociguat on platelets from human immunodeficiency virus (HIV)-positive patients taking abacavir sulfate (ABC)-containing regimens. Our results corroborate a functional role of the NO-GC/cGMP pathway in platelet biomechanics, indicating that biomechanical properties such as stiffness or shape could be used as novel biomarkers in clinical research.

Increased platelet activation and development of thrombosis has been linked to a dysfunctional NO-GC/cGMP signaling pathway. How this pathway affects platelet stiffness, however, has not been studied yet. For the first time, we used novel microscopy techniques to investigate stiffness and shape of platelets in human and murine blood samples treated with cGMP modifying drugs. Stiffness contains information about biomechanical properties of the cytoskeleton, and shape quantifies the spreading behavior of platelets. We showed that the NO-GC/cGMP signaling pathway affects platelet stiffness, shape, and activation in human and murine blood. HIV-positive patients are often treated with medication that may disrupt the NO-GC/cGMP signaling pathway, leading to increased cardiovascular risk. We showed that treatment with cGMP-modifying drugs altered platelet shape and aggregation in blood from HIV-negative volunteers but not from HIV-positive patients treated with medication. Our study suggests that platelet stiffness and shape can be biomarkers for estimating cardiovascular risk.

Activation of mitochondrial DNA-mediated cGAS-STING pathway contributes to chronic postsurgical pain by inducing type I interferons and A1 reactive astrocytes in the spinal cord.

Chronic postsurgical pain (CPSP) is increasingly recognized as a public health issue. Recent studies indicated the innate immune pathway of cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) was involved in pain regulation. However, the detailed mechanisms remain unclear. Previous studies found A1 reactive astrocytes in the spinal cord contributed to CPSP. This study aimed to investigate the roles and mechanisms of the cGAS-STING pathway in regulating the generation of A1 reactive astrocytes during CPSP. First, CPSP model was established using skin/muscle incision and retraction (SMIR) in rats. We found that cGAS-STING pathway was activated accompanied with an increase in mitochondrial DNA in the cytosol in the spinal cord following SMIR. Second, a STING inhibitor C-176 was intrathecally administrated. We found that C-176 decreased the expression of type I interferons and A1 reactive astrocytes in the spinal cord, and alleviated mechanical allodynia in SMIR rats. Third, cyclosporin A as a mitochondrial permeability transition pore blocker was intrathecally administrated. We found that cyclosporin A decreased the leakage of mitochondrial DNA and inhibited the activation of cGAS-STING pathway. Compared with C-176, cyclosporin A exhibits similar analgesic effects. The expression of type I interferons and A1 reactive astrocytes in the spinal cord were also down-regulated after intervention with cyclosporin A. Moreover, simultaneous administration of cyclosporin A and C-176 did not show synergistic effects in SMIR rats. Therefore, our study demonstrated that the cGAS-STING pathway activated by the leakage of mitochondrial DNA contributed to chronic postsurgical pain by inducing type I interferons and A1 reactive astrocytes in the spinal cord.

Combined Inhibition of Phosphodiesterase-5 and -9 in Experimental Heart Failure.

BACKGROUND: Intracellular second messenger cyclic guanosine monophosphate (cGMP) mediates bioactivity of the natriuretic peptides and nitric oxide, and is key to circulatory homeostasis and protection against cardiovascular disease. Inhibition of cGMP-degrading phosphodiesterases (PDEs) PDE5 and PDE9 are emerging as pharmacological targets in heart failure (HF). OBJECTIVES: The present study investigated dual enhancement of cGMP in experimental HF by combining inhibition of PDE-5 (P5-I) and PDE-9 (P9-I). METHODS: Eight sheep with pacing-induced HF received on separate days intravenous P5-I (sildenafil), P9-I (PF-04749982), P5-I+P9-I, and vehicle control, in counterbalanced order. RESULTS: Compared with control, separate P5-I and P9-I significantly increased circulating cGMP concentrations in association with reductions in mean arterial pressure (MAP), left atrial pressure (LAP), and pulmonary arterial pressure (PAP), with effects of P5-I on cGMP, MAP, and PAP greater than those of P9-I. Only P5-I decreased pulmonary vascular resistance. Combination P5-I+P9-I further reduced MAP, LAP, and PAP relative to inhibition of either phosphodiesterase alone. P9-I and, especially, P5-I elevated urinary cGMP levels relative to control. However, whereas inhibition of either enzyme increased urine creatinine excretion and clearance, only P9-I induced a significant diuresis and natriuresis. Combined P5-I+P9-I further elevated urine cGMP with concomitant increases in urine volume, sodium and creatinine excretion, and clearance similar to P9-I alone, despite the greater MAP reductions induced by combination treatment. CONCLUSIONS: Combined P5-I+P9-I amalgamated the superior renal effects of P9-I and pulmonary effects of P5-1, while concurrently further reducing cardiac preload and afterload. These findings support combination P5-I+P9-I as a therapeutic strategy in HF.

Mechanism of cGAS/STING Signaling Pathway in Regulating Lung Cancer and Traditional Chinese Medicine Treatment： A Review / 中国实验方剂学杂志

According to the latest global cancer statistics， the incidence and mortality of lung cancer rank first in China. Classical therapies remain the most common cancer treatment options， such as surgical resection， radiotherapy， and chemotherapy， but not all cancer patients respond to classical therapies， which require new lung cancer treatment strategies. After decades of research and development， cancer immunotherapy has achieved certain curative effect， which provides new possibilities for cancer treatment. Cyclic guanosine monophosphate-adenosine monophosphate synthase （cGAS） is a cytosolic DNA sensor. It can induce protective immune defense responses against various DNA-containing pathogens and provide anti-tumor immunity by activating the interferon （IFN） gene stimulator （STING） protein. At present， relevant researchers in China and abroad have done a lot of research on the occurrence and development of lung cancer and the pathophysiological mechanism of drug intervention in the treatment of lung cancer. The results show that cGAS/STING signaling pathway plays an important role in the development of the disease， and traditional Chinese medicine monomers or compounds can intervene in lung cancer cells by regulating the cGAS/STING signaling pathway， induce their autophagy and death， regulate their cycle operation， promote senescence， inhibit their proliferation and tumor angiogenesis， promote their invasion and metastasis， and promote the immune activation of anti-lung cancer cells， so as to inhibit or delay the occurrence and development of lung cancer. In recent years， the related research results have been updated rapidly， and the previous literature has not included the latest research results in time， which causes a lot of inconvenience for many scholars to search the literature. Based on this， this paper mainly summarized the mechanism of cGAS/STING signaling pathway intervention in lung cancer in China and abroad in recent years， as well as the research progress of related traditional Chinese medicine intervention， so as to provide new ideas for the development of lung cancer in molecular biology， drug treatment research， and clinical new drug research and provide a reference for further mechanism research.

Cell-to-Cell Communications of cGAS-STING Pathway in Tumor Immune Microenvironment / 浙江大学学报·医学版

Targeting cGAS-STING pathway is a promising strategy in tumor treatment. The pattern recognition receptor cGAS identifies dsDNA and catalyzes the formation of the second messenger 2'3'-cGAMP, activating the downstream interferons and pro-inflammatory cytokines through the adaptor protein STING. Notably, in tumor immune microenvironment, key components of cGAS-STING pathway are transferred among neighboring cells. The intercellular transmission under these contexts serves to sustain and amplify innate immune responses while facilitating the emergence of adaptive immunity. The membrane-based system, including extracellular vesicles transport, phagocytosis and membrane fusion transmit dsDNA, cGAMP and activated STING, enhancing the immune surveillance and inflammatory. The membrane proteins, including specific protein channel and intercellular gap junctions, transfer cGAMP and dsDNA, which are crucial to regulate immune responses. And the ligand-receptor interactions for interferons transmission amplifies the anti-tumor response. This review elaborates on the regulatory mechanisms of cell-to-cell communications of cGAS-STING pathway in tumor immune microenvironment. We further explore how these mechanisms modulate immunological processes and discuss potential interventions and immunotherapeutic strategies targeting these signaling cascades.

Unveiling the pathogenic mechanisms of NPR2 missense variants: insights into the genotype-associated severity in acromesomelic dysplasia and short stature.

Introduction: Natriuretic peptide receptor 2 (NPR2 or NPR-B) plays a central role in growth development and bone morphogenesis and therefore loss-of-function variations in NPR2 gene have been reported to cause Acromesomelic Dysplasia, Maroteaux type 1 and short stature. While several hypotheses have been proposed to underlie the pathogenic mechanisms responsible for these conditions, the exact mechanisms, and functional characteristics of many of those variants and their correlations with the clinical manifestations have not been fully established. Methods: In this study, we examined eight NPR2 genetic missense variants (p.Leu51Pro, p.Gly123Val, p.Leu314Arg, p.Arg318Gly, p.Arg388Gln, p.Arg495Cys, p.Arg557His, and p.Arg932Cys) Acromesomelic Dysplasia, Maroteaux type 1 and short stature located on diverse domains and broadly classified as variants of uncertain significance. The evaluated variants are either reported in patients with acromesomelic dysplasia in the homozygous state or short stature in the heterozygous state. Our investigation included the evaluation of their expression, subcellular trafficking and localization, N-glycosylation profiles, and cyclic guanosine monophosphate (cGMP) production activity. Results and Discussion: Our results indicate that variants p.Leu51Pro, p.Gly123Val, p.Leu314Arg, p.Arg388Gln have defective cellular trafficking, being sequestered within the endoplasmic reticulum (ER), and consequently impaired cGMP production ability. Conversely, variants p.Arg318Gly, p.Arg495Cys, and p.Arg557His seem to display a non-statistically significant behavior that is slightly comparable to WT-NPR2. On the other hand, p.Arg932Cys which is located within the guanylyl cyclase active site displayed normal cellular trafficking profile albeit with defective cGMP. Collectively, our data highlights the genotype-phenotype relationship that might be responsible for the milder symptoms observed in short stature compared to acromesomelic dysplasia. This study enhances our understanding of the functional consequences of several NPR2 variants, shedding light on their mechanisms and roles in related genetic disorders which might also help in their pathogenicity re-classification.

Augmentation of natriuretic peptide (NP) receptor A and B (NPR-A and NPR-B) and cyclic guanosine monophosphate (cGMP) signalling as a therapeutic strategy in heart failure.

INTRODUCTION: Heart failure is a complex, debilitating condition and despite advances in treatment, it remains a significant cause of morbidity and mortality worldwide. Therefore, the need for alternative treatment strategies is essential. In this review, we explore the therapeutic strategies of augmenting natriuretic peptide receptors (NPR-A and NPR-B) and cyclic guanosine monophosphate (cGMP) in heart failure. AREAS COVERED: We aim to provide an overview of the evidence of preclinical and clinical studies on novel heart failure treatment strategies. Papers collected in this review have been filtered and screened following PubMed searches. This includes epigenetics, modulating enzyme activity in natriuretic peptide (NP) synthesis, gene therapy, modulation of downstream signaling by augmenting soluble guanylate cyclase (sGC) and phosphodiesterase (PDE) inhibition, nitrates, c-GMP-dependent protein kinase, synthetic and designer NP and RNA therapy. EXPERT OPINION: The novel treatment strategies mentioned above have shown great potential, however, large randomized controlled trials are still lacking. The biggest challenge is translating the results seen in preclinical trials into clinical trials. We recommend a multi-disciplinary team approach with cardiologists, geneticist, pharmacologists, bioengineers, researchers, regulators, and patients to improve heart failure outcomes. Future management can involve telemedicine, remote monitoring, and artificial intelligence to optimize patient care.

Role of cGAS-STING signaling pathway in cardiometabolic diseases. / cGAS-STINGé€šè·¯åœ¨ä»£è°¢æ€§å¿ƒè¡€ç®¡ç–¾ç— ä¸­çš„ä½œç”¨.

Cardiometabolic disease is a common clinical syndrome with exact causal relationship between the aberrant of glucose/lipid metabolism and cardiovascular disfunction, but its pathogenesis is unclear. Cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon gene (STING) signaling pathway regulates the activation of innate immunity by sensing intracellular double stranded DNA. Metabolic risk factors drive the activation of cGAS-STING pathway through mitochondrial DNA, nuclear DNA and endoplasmic reticulum stress. In addition, the activation of the cGAS-STING pathway triggers chronic sterile inflammation, excessive activation of autophagy, senescence and apoptosis in related cells of cardiovascular system. These changes induced by cGAS-STING pathway might be implicated in the onset and deterioration of cardiometabolic disease. Therefore, the targeting intervention of cGAS-STING signaling pathway may emerge as a novel treatment for cardiometabolic disease.

The anti-cancer effect of epigallocatechin-3-O-gallate against multiple myeloma cells is potentiated by 5,7-dimethoxyflavone.

(-)-Epigallocatechin-3-O-gallate (EGCG) is one of the major components of green tea polyphenol. Previous studies have shown that EGCG induces cancer-specific cell death in vitro and in vivo without causing severe side effects. However, the anti-cancer effect of EGCG alone is limited. 5,7-dimethoxyflavone (5,7-DMF), one of the principal functional components of black ginger (Kaempferia parviflora), also exerts anti-cancer effects. Here, we show that 5,7-DMF synergistically enhances the anti-cancer effect of EGCG in multiple myeloma cells by potentiating EGCG-induced intracellular cyclic guanosine monophosphate (cGMP) production. Moreover, the combination of EGCG and 5,7-DMF induces apoptotic cell death in multiple myeloma cells, and this is accompanied by activation of the cGMP/acid sphingomyelinase (ASM)/cleaved caspase-3 pathway. In conclusion, we have shown that 5,7-DMF enhances the anti-cancer effect of EGCG by upregulating cGMP in multiple myeloma cells.

Stimulation of Erythrocyte Soluble Guanylyl Cyclase Induces cGMP Export and Cardioprotection in Type 2 Diabetes.

Reduced nitric oxide (NO) bioactivity in red blood cells (RBCs) is critical for augmented myocardial ischemia-reperfusion injury in type 2 diabetes. This study identified the nature of "NO bioactivity" by stimulating the intracellular NO receptor soluble guanylyl cyclase (sGC) in RBCs. sGC stimulation in RBCs from patients with type 2 diabetes increased export of cyclic guanosine monophosphate from RBCs and activated cardiac protein kinase G, thereby attenuating ischemia-reperfusion injury. These results provide novel insight into RBC signaling by identifying cyclic guanosine monophosphate from RBC as a mediator of protection against cardiac ischemia-reperfusion injury induced by sGC stimulation in RBCs.

New Therapeutics for Heart Failure: Focusing on cGMP Signaling.

Current drugs for treating heart failure (HF), for example, angiotensin II receptor blockers and ß-blockers, possess specific target molecules involved in the regulation of the cardiac circulatory system. However, most clinically approved drugs are effective in the treatment of HF with reduced ejection fraction (HFrEF). Novel drug classes, including angiotensin receptor blocker/neprilysin inhibitor (ARNI), sodium-glucose co-transporter-2 (SGLT2) inhibitor, hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker, soluble guanylyl cyclase (sGC) stimulator/activator, and cardiac myosin activator, have recently been introduced for HF intervention based on their proposed novel mechanisms. SGLT2 inhibitors have been shown to be effective not only for HFrEF but also for HF with preserved ejection fraction (HFpEF). In the myocardium, excess cyclic adenosine monophosphate (cAMP) stimulation has detrimental effects on HFrEF, whereas cyclic guanosine monophosphate (cGMP) signaling inhibits cAMP-mediated responses. Thus, molecules participating in cGMP signaling are promising targets of novel drugs for HF. In this review, we summarize molecular pathways of cGMP signaling and clinical trials of emerging drug classes targeting cGMP signaling in the treatment of HF.

The effect of acupuncture on lateral habenular nucleus and intestinal microflora in depression model rats.

BACKGROUND: Depression is a severe emotional condition that significantly affects the quality of life. Acupuncture exerts preventive effects on depression in rats with post-chronic unpredictable mild stress (CUMS). Methods The study involved chronic unpredictable mild stress (CUMS) depression model mice to administer acupuncture as a preventative measure to investigate the mechanism of acupuncture's antidepressant and observe the effect of acupuncture on impact via the Lateral Habenula (LHb) and Gut-Liver-Brain Axis. The researcher investigated molecules correlating with a nitric oxide/cyclic guanosine monophosphate (NO/cGMP) pathway and assessed inflammation in the LHb and liver. In addition, 16 S rDNA bioinformatics study revealed the quantity and variety of gut microbiota. Rats were randomly divided into five groups: control (CON), CUMS, CUMS + acupuncture (AP), CUMS + fluoxetine (FX) and CUMS + N(G) -nitro -L- arginine methyl ester (LNAME) group. Except for the CON group, other rats were exposed to CUMS condition for 28 days. Simultaneously, manual acupuncture (at Fengfu and Shangxing acupoints, once every other day) and fluoxetine gavage (2.1 mg/kg, 0.21 mg/mL, daily) were conducted to the groups of AP and FX, respectively, after stressors. Rats in LNAME group were treated with LNAME normal saline (10 mg/kg, 1 mg/mL, i.p.) solution. Behavioural tests and biological detection methods were conducted sequentially to evaluate depressionlike phenotype in rats. RESULTS: The results showed CUMS induced depression-like behaviours, hyper-activation of NO/cGMP signaling pathway, inflammation in serum, LHb and liver, and dysbiosis of the gut microbiota. These changes could be prevented and ameliorated by acupuncture to varying extents. CONCLUSION: Acupuncture prevented and attenuated depression-like phenotype induced by CUMS, possibly via regulating the NO/cGMP signaling pathway and thus improving inflammation in serum, LHb and liver, and gut microbiota dysbiosis. In addition, these can be evidence of the existence of the gut-liver-brain axis.

Sensing Cytosolic DNA Lowers Blood Pressure by Direct cGAMP-Dependent PKGI Activation.

BACKGROUND: The major cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) has emerged as a key mediator of inflammation that underlies cardiovascular disease. On interaction with double-stranded DNA, cGAS generates the second messenger 2',3'-cyclic GMP-AMP (cGAMP) that directly binds to and activates the stimulator of interferon genes, which in turn leads to enhanced expression of genes encoding interferons and proinflammatory cytokines. Here, we show that cGAMP generated by cGAS also directly activates PKGI (cGMP-dependent protein kinase 1), a mechanism that underlies crosstalk between inflammation and blood pressure regulation. METHODS: The ability of cGAS and cGAMP to activate PKGI was assessed using molecular, cellular, and biochemical analyses, and in myography experiments, as well. The release of cGAMP from the endothelium was measured using an ELISA, and its uptake into the vascular smooth muscle was assessed using molecular and biochemical approaches, including the identification and targeting of specific cGAMP transporters. The blood pressure of wild-type and cGAS-/- mice was assessed using implanted telemetry probes. cGAS was activated by in vivo transfection with G3-YSD or mice were made septic by administration of lipopolysaccharide. RESULTS: The detection of cytosolic DNA by cGAS within the vascular endothelium leads to formation of cGAMP that was found to be actively extruded by MRP1 (multidrug resistance protein 1). Once exported, this cGAMP is then imported into neighboring vascular smooth muscle cells through the volume-regulated anion channel, where it can directly activate PKGI. The activation of PKGI by cGAMP mediates vasorelaxation that is dependent on the activity of MRP1 and volume-regulated anion channel, but independent of the canonical nitric oxide pathway. This mechanism of PKGI activation mediates lowering of blood pressure and contributes to hypotension and tissue hypoperfusion during sepsis. CONCLUSIONS: The activation of PKGI by cGAMP enables the coupling of blood pressure to cytosolic DNA sensing by cGAS, which plays a key role during sepsis by mediating hypotension and tissue hypoperfusion.