Cyclic guanosine monophosphate (GMP)-AMP synthase (cGAS) is a critical cytosolic DNA sensor, whose activity can be regulated by acetylation. Here, we show that nicotinamide adenine dinucleotide (NAD+)-dependent lysine deacetylase SIRT4 interacts with cGAS and positively regulates innate immune responses triggered by DNA viruses or cytoplasmic DNA. Overexpression of SIRT4 inhibits HSV-1 infection, whereas knockdown of SIRT4 has the opposite effect. Deficiency of SIRT4, or treatment with a SIRT4 inhibitor, impairs antiviral innate immune signaling in response to DNA viruses or cytoplasmic DNA, both in vitro and in vivo. Moreover, SIRT4 inhibitor treatment attenuates type I interferon signaling in Trex1-deficient cells and in peripheral blood mononuclear cells (PBMCs) from patients with systemic lupus erythematosus (SLE). Mechanistically, SIRT4 deacetylates cGAS and enhances its association with double‑stranded DNA. Collectively, our study identifies SIRT4 as a positive regulator of cGAS-mediated innate immune signaling pathways, which advances the understanding of the regulation of cGAS activity.

Kininogen-1 modulates cGMP-PKG signaling to alleviate inflammatory neuronal injury in intracerebral hemorrhage.

Urine cyclic guanosine monophosphate (cGMP) has been proposed as a prognostic biomarker for therapy response and the risk of relapse of cervical cancer after treatment with radiotherapy (RT). In the present study, an in vitro model with cervical cancer cells (C4-1) was established to determine whether changes in extracellular cGMP levels were predictive for effects of ionization radiation (IR). During exponential growth, C4-1 cells were exposed to IR with doses between 2 and 12 Gy. The cells were harvested at intervals between one and six days. The effect of IR on cell growth and extracellular cGMP levels was dose- as well as time-dependent. Three and six days after IR, the cell fractions were reduced with identical sensitivity (ED50 of 1.9 and 1.8 Gy, respectively). The extracellular cGMP levels showed a fall from the first day to sixth day, both in control and after irradiation (2 and 4 Gy), but with somewhat higher levels after IR. However, the extracellular cGMP levels increased after 8 and 12 Gy exposure by 100% and 270%, respectively. When the data were presented as extracellular cGMP levels (% above control), a clear dose- and time-dependency were observed. From a translational perspective, extracellular cGMP levels may be used to monitor effects and be a potential tool for individualization of radiation therapy (RT).

The cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase-stimulator of interferon genes (cGAS-STING) pathway is crucial for tumor immunity. However, activation of the cGAS-STING pathway alone is seldom sufficient to eliminate established tumors. Here, we report the engineering of zinc/manganese (Zn/Mn)-based metal-organic framework (MOF) nanoparticles, that is, AMP@Zn/Mn-MOF, comprising Zn/Mn-MOF nanoparticles as the carrier and the STING agonist c-di-AMP diammonium as the therapeutic drug for reinforcing antitumor immune responses. These therapeutic nanoplatforms can significantly activate the cGAS‒STING pathway and facilitate the innate immune response. Furthermore, the peroxidase (POD)-mimetic and glutathione oxidase (GSHox)-mimetic activities of AMP@Zn/Mn-MOF can significantly potentiate tumor cell death and effectively induce robust immunogenic cell death (ICD), thereby amplifying the cGAS-STING pathway. Moreover, AMP@Zn/Mn-MOF reprogrammed the immunosuppressive tumor microenvironment by promoting intratumoral lymphocyte infiltration, thereby significantly suppressing the growth of murine MC38 tumors in mice. Notably, AMP@Zn/Mn-MOF amplified the therapeutic effect of anti-programmed death ligand 1 (αPD-L1) blockade by triggering systemic antitumor responses, resulting in a notable abscopal effect to effectively inhibit distant tumors. In summary, AMP@Zn/Mn-MOF offers a nanoplatform with enhanced antitumor effectiveness through activation of the cGAS-STING pathway and ICD, suggesting that enhanced immune checkpoint blockade-based immunotherapy is promising for colon cancer treatment.

Background/Objectives: The present study investigated the local analgesic effect of a novel synthetic cyclohexanone derivative, 2,6-bis-4-(hydroxyl-3-methoxybenzilidine)-cyclohexanone, or BHMC, in a mouse model of peripheral nociception. Methods: Local administration of BHMC (0.5–60 µg/paw) intra-plantarly in the hindpaws of mice exhibited significant inhibition in carrageenan-induced paw hyperalgesia. Intra-plantar pretreatment of naloxone (non-selective opioid receptor blocker), D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-ThrNH2 (CTOP, selective µ-opioid receptor blocker), and nor-binaltorphimine (nor-BNI, selective κ-opioid receptor blocker), but not naltrindole hydrochloride (selective δ-opioid receptor blocker), reversed the anti-nociceptive effect of BHMC. The peripheral analgesic effect of BHMC was also reversed by intra-plantar pretreatment of methylene blue (soluble guanosyl cyclase blocker), but not NG-nitro-L-arginine (L-NAME, nitric oxide synthase blocker). Involvement of the potassium channel in the local analgesic effect of BHMC was shown through the reversed analgesic effect by intra-plantar pretreatment of glibenclamide (ATP-sensitive potassium channel blocker), but not by charybdotoxin (large-conductance calcium-sensitive potassium channel blocker), apamin (small-conductance calcium-sensitive potassium ion channel blocker), or tetraethylammonium (voltage-sensitive potassium channel blocker). Results: Taken together, the present study demonstrated that the local administration of BHMC attenuated nociception, with possible mechanisms that may involve the desensitization of inflammatory mediators’ receptors, opioid receptor activation, and nitric oxide-independent cyclic guanosine monophosphate activation of ATP-sensitive potassium ion channel opening. Conclusions: The current findings may further support the exploration of BHMC as a new therapeutic agent for pain and inflammation, for the betterment of human health.

Natriuretic Peptide Receptor-1 Agonist for Resistant Hypertension: A Randomized Phase 2 Trial.

Cyclic guanosine monophosphate (cGMP) improves freezing tolerance of sheep embryos by reducing lipid content.

Acute kidney injury (AKI) frequently progresses to chronic kidney disease (CKD), resulting in long-term renal dysfunction. Although traditional risk factors such as hypertension, diabetes, and aging contribute to this transition, endothelial dysfunction has emerged as a central mediator. In a murine model of severe ischemia-reperfusion injury (IRI), we observed persistent fibrosis with sustained activation of β-catenin signaling, especially when there is an endothelial nitric oxide synthase (eNOS) deficiency. Impaired nitric oxide (NO)-cyclic guanosine monophosphate (cGMP)-protein kinase G (PKG) signaling exacerbated fibrosis by failing to suppress β-catenin activity. RNA sequencing at day 7 post-IRI revealed upregulation of genes related to macrophage differentiation. Flow cytometry demonstrated a biphasic macrophage response: CD11b+F4/80low (M1-like) macrophages predominated on day 1, shifting to CD11b+F4/80high (M2-like) macrophages by day 3, and then resolving by day 7. However, in eNOS knockout mice, M2 macrophages persisted beyond day 3, indicating sustained fibrogenic signaling. In vitro, NO-cGMP-PKG signaling inhibited IL-4-induced M2 polarization via β-catenin degradation, linking endothelial dysfunction to prolonged M2 activation. In vivo, macrophage depletion in eNOS-deficient mice significantly reduced interstitial fibrosis and improved renal function, confirming an important pathogenic role of M2 macrophages in AKI-to-CKD progression. Furthermore, pharmacological enhancement of cGMP signaling using a phosphodiesterase-5 (PDE5) inhibitor from day 7 post-IRI ameliorated fibrosis. Together, these findings suggest that endothelial dysfunction promotes a profibrotic macrophage milieu via Wnt/β-catenin activation and highlights the therapeutic potential of targeting NO-cGMP-β-catenin signaling to prevent CKD progression following AKI.NEW & NOTEWORTHY Our study provides novel insights into the mechanisms underlying the transition from acute kidney injury (AKI) to chronic kidney disease (CKD), with a focus on the role of endothelial nitric oxide synthase (eNOS). We believe our findings, particularly their potential implications for developing new therapeutic strategies to prevent CKD progression, will be of significant interest to your readership and could significantly improve patient care.

Myocardial PKG1α dysregulation contributes to ventricular tachycardia pathogenesis in type 2 diabetes and metabolic syndrome.

Phosphodiesterase: insight from molecular targets for glycolipid metabolism.

IFI16 senses and protects stalled replication forks.

Artesunate ameliorates leflunomide low-response against bone destruction in rheumatoid arthritis via cGMP-PKG signalling.

Dear Editor, Chronic obstructive pulmonary disease (COPD) is a disease related to the respiratory system which causes bronchoconstriction and excess release of mucus leading to airway remodeling and obstruction. This condition is also involved with airway inflammation and oedema. Statistically, according to WHO, chronic obstructive pulmonary disease is the third leading cause of death worldwide. (1) Over the past four decades, standard-of-care COPD treatment has been based on inhaled short- and long-acting bronchodilators [including long-acting beta 2 agonists (LABAs) and long-acting muscarinic receptor antagonists (LAMAs)] and inhaled corticosteroids. (1)Still, patients may remain largely symptomatic due to the wide range of spectrum of COPD complications, often requiring concomitant use of both bronchodilators and anti-inflammatory drugs. Furthermore, their use is limited due to several reasons. They are unable to reverse airway wall damage and they cannot stimulate lung regeneration. Also, there is very limited sensitivity of the inflamed airways to the available medical options. Lastly, there are side effects associated with their use hence these reasons limit their use. (2) Ensifentrine (RPL554) is the latest FDA-approved advancement available for COPD. It is a novel drug that works by dual inhibition of phosphodiesterase (PDE) 3 and 4 enzymes (PDE3, PDE4) and is delivered via inhalation. Inhibitors of PDE3 and PDE4 target multiple respiratory functions at the cellular and tissue level. PDE3 regulates cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) levels in the airway smooth muscles, which mediates bronchial tone. PDE4 regulates cAMP levels in the airway cells associated with inflammation and is involved in activation of these cells. PDE4 inhibitors also stimulate the cystic fibrosis transmembrane conductance regulator (CFTR) and improve bronchial epithelial cell ciliary movements (3) This dual inhibition of PDE3 and PDE4 enzymes results in a synergistic effect, making Ensifentrine the first ever drug to treat both COPD associated inflammation as well as bronchoconstriction. (4) Ensifentrine not only delivers significant improvement in lung function as sole therapy at doses of 3 mg and 6 mg (4) but also its pivotal role as an adjuvant to existing treatment regimens comprising long-acting muscarinic antagonists (LAMA) or long-acting beta-agonists with inhaled corticosteroids (LABA Plus ICS), as well as enhancing their combined efficacy over longer periods (5) has now been clearly demonstrated and documented.

Phosphodiesterases (PDEs) are a huge superfamily of enzymes that fine-tune the intracellular levels of cyclic nucleotides -cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP)-thus playing a pivotal role in the control of many cellular processes. While traditionally studied in the context of cardiovascular and neurological systems, mounting evidences highlight a crucial involvement of PDEs in metabolic homeostasis. This review explores the expanding landscape of PDEs function beyond classical cyclic nucleotide degradation, focusing on their roles in glucose and lipid metabolism and their implications in metabolic disorders, including obesity, type 2 diabetes (T2DM), and metabolic syndrome (MetS). Starting from an overview of the PDE superfamily, this work deeply examines the compartmentalized actions of cAMP-dependent protein kinase A (PKA) and cGMP-dependent protein kinase G (PKG) signaling pathways in key metabolically active tissues integrating PDE activities across different organs and disease states to offer a holistic view of their metabolic relevance. Special attention is given to the therapeutic relevance of PDE inhibitors (PDEi), distinguishing between established applications and emerging strategies targeting specific PDE isoforms in metabolic disease contexts to underscore the evolving concept that PDEs act as dynamic regulators of metabolic signaling networks. Understanding their isoform-specific and tissue-specific actions could thus open new avenues for therapeutic intervention in complex metabolic disorders.

Background Prostate cancer is one of the most common malignancies in men, and immune escape is one of the major challenges in development and treatment. In a hypoxic environment, tumor cells may reduce or stop expressing antigens, thereby avoiding recognition by the immune system and increasing the risk of immune escape. Purpose The purpose of this study is to explore the inhibitory effect of the calcitonin gene-related peptide (CGRP)-carrying liposome nano-delivery system on the immune escape of prostate cancer cells under hypoxic conditions and further to study its related mechanism with the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signaling pathway. Materials and Methods A hypoxic PC-3 culture model was constructed and divided into four groups: Control group (no treatment of prostate cancer cells), Low_Oxygen_1 group (5% hypoxic environment + prostate cancer cells), Low_Oxygen_2 group (3% hypoxic environment + prostate cancer cells), Low_Oxygen_3 group (1% hypoxic environment + prostate cancer cells). For the co-cultivation of the obtained CGRP-low-density lipoprotein (LDL) delivery system with PC-3 cells, they were divided into Low_Oxygen + CGRP-LDL + hypoxia group, CGRP-LDL group, CGRP group, and Low_Oxygen + CGRP group. The apoptosis rate was detected, and the key protein of immune escape of PC-3 cells was analyzed to determine whether the immunosuppressive effect of CGRP-LDL on PC-3 under hypoxic conditions was realized through the NO-cGMP pathway. Results GRP-liposome carrying liposome (LCL) was successfully constructed, and the immune escape of prostate cancer cells was found in a hypoxic environment; the lower the oxygen concentration, the higher the degree of escape. The Low_Oxygen_2 group (3% hypoxic environment + CGRP-LCL group) had the most significant anti-cancer effect in the hypoxic environment, with the lowest proliferation and highest apoptosis (vs. other groups, p < .05). Liposome nano-delivery system carrying CGRP has a good anti-cancer effect. Further endothelial nitric oxide synthase (eNOS) messenger ribonucleic acid (mRNA) silencing and comparative verification using the nitric oxide synthase (NOS) inhibitor NG-nitro- l -arginine methyl ester (L-NAME) revealed that the nano-delivery system had a positive effect on the NO-cGMP signaling pathway of prostate cancer cells in a hypoxic environment. The 3% hypoxic environment + GCRP-LCL system group had the best intervention effect, and the G protein, cGMP concentration, and NO synthase activity were the highest (vs. other groups, p < .001). We added the NOS inhibitor L-NAME group and detected related proteins, and found that the CGRP-LCL group was significantly lower than the NOS inhibitor L-NAME group, which indicated that CGRP-LCL inhibited the immune escape of PC-3 cells. Conclusion A hypoxic environment can increase the phenomenon of immune escape of tumor cells, but the application of the CGRP-LCL nano-delivery system can intervene in this process. CGRP-LCL nano-delivery system can inhibit the immune escape of prostate cancer cells in a hypoxic environment. The expression of key proteins is inhibited, and this inhibitory effect is mainly exerted through the activation of the NO-cGMP signaling pathway.

Chronic heart failure with reduced ejection fraction (HFrEF) is a progressive syndrome associated with substantial residual morbidity and mortality despite contemporary guideline-directed medical therapy (GDMT) - angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs)/angiotensin receptor-neprilysin inhibitors (ARNIs), beta-blockers, mineralocorticoid receptor antagonists (MRAs) and sodium-glucose cotransporter-2 inhibitors (SGLT2is) [1]. Consequently, the need for novel therapeutic strategies has led to the exploration of new drug classes and pathways. In HF, impaired nitric-oxide (NO) signaling, reduced soluble guanylate cyclase (sGC) responsiveness/abundance, and downstream attenuation of cyclic guanosine monophosphate (cGMP) contribute to disease progression [2]. Vericiguat-an oral sGC stimulator-sensitizes sGC to endogenous NO and directly stimulates the enzyme, thereby restoring cGMP signaling in vascular smooth muscle and cardiomyocytes.

Abstract Introduction Nitric Oxide boosting supplements improve circulation by increasing cGMP. PDE-5 inhibitors work by blocking PDE- 5, which increases NO mediated blood flow to the penis by enhancing cyclic GMP. There is limited objective data on the synergistic effects of NO boosting dietary supplements and PDE-5 inhibitors. The NO boosting dietary supplement used in this study consists of L-citrulline, Red Beet Root extract, Panax Ginseng Root Extract, and Muira Puama Extract. The kidneys convert L-citrulline into Arginine, which produces NO that relaxes blood vessels and improves blood flow. Beetroot extract has a high nitrate content, which the body converts into NO. Nighttime erections can be measured and provide an objective indicator of erectile health. Objective We investigated whether ingesting a NO boosting dietary supplement and Sildenafil 40 mg one hour before sleep can improve nighttime erectile function compared to Sildenafil 40 alone by using the TechRing by FirmTech to measure penile pressure while sleeping. Methods 22 men completed the study. Average age 55. Average SHIM score 18.1. A single tablet of the NO boosting dietary supplement contains 750 mg L-Citrulline, 65 mg Muira Puama Extract 4:1, Red Beet Root extract 45mg 4:1, Panax Ginseng Root Extract 35mg 4:1. This supplement is commercially available as AFFIRM. Participants wore the TechRing during sleep to measure nighttime erectile function. The TechRing uses two sensors and an AI interface to measure the firmness and duration of erections. The protocol was a 2-day washout period with no ejaculation, ED medications, or supplements. Days 1&2 participants ingested Sildenafil 40 mg one hour before bedtime and wore the TechRing while sleeping. Days 3&4 participants ingested two supplement tablets and Sildenafil 40 mg 1 hour before sleep and wore the TechRing. We calculated the area under the curve per hour of sleep (AUC/hr) as reported by the TechRing as a measure of erectile activity. Results The AUC/hr of the men taking Sildenafil 40mg with no dietary supplement was 87, and the AUC/hr on the two days when participants took Sildenafil 40mg and the supplement was 117. The difference in means was 30 (34% increase), and the p-value was 0.00004. (t=5.219) The mean number of erections per night was 3.25 with Sildenafil 40mg and no dietary supplement, and 3.87 with Sildenafil 40mg and the dietary supplement. There was a slight significant difference in the number of erections per night (p-value 0.034 (t=2.285)). No side effects were self-reported from taking the dietary supplement or Sildenafil 40mg at bedtime. Conclusions The combination of Sildenafil 40mg and a NO boosting dietary supplement increased the duration and intensity of nighttime erections compared to Sildenafil 40 mg alone as measured by the TechRing. This NO boosting dietary supplement improves genital circulation at night. This NO boosting supplement may also be synergistic with Sildenafil and improve genital circulation during awake sexual activity. Many men who take PDE-5 inhibitors will get side effects. Taking a Nitric Oxide boosting dietary supplement may boost the effectiveness of a PDE-5 inhibitor without generating side effects that can limit the dose. Disclosure Any of the authors act as a consultant, employee or shareholder of an industry for: AFFIRM Science, FirmTech

Pericytes are mural cells that line capillaries throughout the brain, retina, lung, and other organs, where they support capillary homeostasis through direct contact and paracrine crosstalk with capillary endothelium. Despite being described more than a century ago, their contributions to health and vascular diseases remain unclear, largely due to the difficulty of definitive identification. Their inherent plasticity, as well as shared markers and close lineage relationships with other mural cells, results in overlap in identification and underrepresentation in single-cell data sets. Emerging evidence reveals that pericytes play a critical role in the vascular remodeling characteristics of pulmonary hypertension, via mechanisms involving smooth muscle-like phenotypic switching and morphological changes influenced by hypoxia signaling, transforming growth factor-β, cyclic GMP modulation, and disrupted pericyte-endothelial communication. Recent single-cell RNA sequencing enabled the identification of a novel and specific pericyte marker, Higd1b, thereby improving pericyte identification and revealing novel pericyte subtypes. In this review, we summarize historical and recent insights into pericyte morphology and function, their increasingly recognized role in pulmonary hypertension pathobiology, and the potential to unlock novel therapeutic avenues targeting pericytes.

Chrysoeriol, a flavonoid naturally found in several plants, including Danggui Susan, a traditional herbal medicine, exhibits promising anti-inflammatory and antioxidant properties. Its potential to prevent cardiovascular diseases, primarily through inhibiting platelet activation and aggregation, has attracted significant interest. This study aimed to investigate the molecular mechanisms underlying the antiplatelet effects of chrysoeriol. The compound effectively suppressed collagen-induced platelet aggregation without inducing cytotoxicity. Chrysoeriol elevated intracellular levels of cyclic AMP (cAMP) and cyclic GMP (cGMP), enhanced inositol 1,4,5-trisphosphate receptor (IP3R) phosphorylation, and reduced cytosolic calcium (Ca2+) mobilization, all of which contributed to its antiplatelet action. Furthermore, chrysoeriol inhibited the phosphorylation of PI3K, Akt, JNK, and p38 MAPK, pathways involved in the activation of cytosolic phospholipase A2 (cPLA2) and thromboxane A2 (TXA2) production. These effects were accompanied by reduced TXA2 production and secretion of dense granules (ATP and serotonin). Chrysoeriol also impaired thrombin-induced clot retraction, further suggesting its capacity to regulate platelet responses and cytoskeletal rearrangements. These findings highlight chrysoeriol’s multi-target mechanisms, including modulation of cyclic nucleotides, kinase pathways, and platelet function, offering potential as a therapeutic agent to prevent thrombotic cardiovascular events.

The Type III Secretion System (T3SS) of Pseudomonas aeruginosa injects effector proteins into host cells to subvert cellular processes and promote infection. While the roles of several T3SS effectors in virulence are well established, the function of the nucleotidyl cyclase ExoY has remained elusive and debated. Here, we show that ExoY-produced cyclic GMP (cGMP) regulates the cytotoxic activity of the co-injected effector ExoT, thereby modulating host cell damage. Using engineered P. aeruginosa strains expressing ExoY variants with distinct substrate preferences, we demonstrate that cGMP production by ExoY limits ExoT-mediated dephosphorylation of the host adaptor protein CrkII, a downstream consequence of ExoT's ADP-ribosyltransferase activity. This attenuation reduces ExoT-induced cell retraction and decreases bacterial virulence. In contrast, we find that ExoT and another T3SS effector, ExoS, can inhibit ExoY activity and cGMP production in certain cell types, thus limiting ExoY's regulatory influence. These findings highlight the intricate interplay between T3SS effectors within host cells and reveal an unrecognized layer of ExoY-based complexity in P. aeruginosa's pathogenic strategy.