Guanosine Monophosphate Signaling Pathway Research Articles

Stem cell-homing biomimetic hydrogel promotes the repair of osteoporotic bone defects through osteogenic and angiogenic coupling.

Osteoporotic bone defects refer to the disruption of bone structural integrity in patients with osteoporosis and pose a substantial challenge to orthopedic surgeons. In this study, we developed a biomimetic hydrogel to improve the osteogenic microenvironment and promote stem cell homing. This hydrogel served as a container for S-nitrosoglutathione and Ca2+, promoting the release of bioactive nitric oxide (NO) from bone marrow mesenchymal stem cells (BMSCs) and human vascular endothelial cells and activating the NO/cyclic guanosine monophosphate signaling pathway. These changes promote osteogenic and angiogenic couplings. The hydrogel simultaneously recruited BMSCs by conjugating the stem cell homing peptide SKPPGTSS. Using a rat distal femoral defect model, it was demonstrated that this hydrogel can effectively increase the formation of bone tissue and new blood vessels and has immune-regulating functions. We envision that this hydrogel may be a minimally invasive yet highly effective strategy for expediting the healing of osteoporotic bone defects.

The Role of Nitric Oxide in the Proconvulsant Effect of Paraxanthine During the Intravenous Pentylenetetrazole Seizure Threshold Test in Mice

Background: Paraxanthine is the major metabolite of caffeine in humans. There is no definitive proof that paraxanthine affects seizures. Nitric oxide (NO) contributes to the central effects of paraxanthine. Objectives: In this study, we examined the effect of acute paraxanthine administration on the pentylenetetrazole (PTZ)-induced seizure threshold, focusing on the NO-cyclic guanosine monophosphate (cGMP) signaling pathway. Methods: Naval Medical Research Institute (NMRI) male mice (25 - 30 g) received paraxanthine (5, 10, 50, and 100 mg/kg) alone. L-arginine [a substrate for NO synthase (NOS)] (50 mg/kg) or L-NAME [a non-selective NOS inhibitor] (5 mg/kg) was administered alone or as pretreatment before the ineffective or effective doses of paraxanthine, respectively. The intravenous PTZ seizure threshold test was used to determine the thresholds for the onset of myoclonic twitch (MCT), generalized clonus (GNC), and forelimb tonus (FLT). Nitric oxide metabolites (NOx) were measured using the Griess method. Results: Paraxanthine administered at doses of 10 and 50 mg/kg significantly reduced the threshold for FLT (P < 0.05 for both). At a dose of 100 mg/kg, paraxanthine significantly reduced the thresholds for the onset of MCT (P < 0.001), GNC (P < 0.01), and FLT (P < 0.001). L-arginine (50 mg/kg), either alone or as pretreatment before paraxanthine (5 mg/kg), did not significantly change the seizure threshold. L-NAME (5 mg/kg) alone had no effect, but L-NAME pretreatment before paraxanthine (100 mg/kg) significantly increased the thresholds for the onset of MCT (P < 0.001), GNC (P < 0.001), and FLT (P < 0.001). Only paraxanthine at a dose of 100 mg/kg significantly increased NOx levels in brain tissues (P < 0.05). Pretreatment with L-arginine further increased the NOx level (P < 0.001), whereas pretreatment with L-NAME decreased it (P < 0.001) compared to the paraxanthine groups. Conclusions: Our results show that paraxanthine has a proconvulsant effect. The results of L-arginine or L-NAME pretreatment before paraxanthine support the possible interaction of the NO-cGMP pathway in the proconvulsant effect of paraxanthine.

A photothermal responsive system accelerating nitric oxide release to enhance bone repair by promoting osteogenesis and angiogenesis

Managing bone defects remains a formidable clinical hurdle, primarily attributed to the inadequate orchestration of vascular reconstruction and osteogenic differentiation in both spatial and temporal dimensions. This challenge persists due to the constrained availability of autogenous grafts and the limited regenerative capacity of allogeneic or synthetic bone substitutes, thus necessitating continual exploration and innovation in the realm of functional and bioactive bone graft materials. While synthetic scaffolds have emerged as promising carriers for bone grafts, their efficacy is curtailed by deficiencies in vascularization and osteoinductive potential. Nitric oxide (NO) plays a key role in revascularization and bone tissue regeneration, yet studies related to the use of NO for the treatment of bone defects remain scarce. Herein, we present a pioneering approach leveraging a photothermal-responsive system to augment NO release. This system comprises macromolecular mPEG-P nanoparticles encapsulating indocyanine green (ICG) (NO-NPs@ICG) and a mPEG-PA-PP injectable thermosensitive hydrogel carrier. By harnessing the synergistic photothermal effects of near-infrared radiation and ICG, the system achieves sustained NO release, thereby activating the soluble guanylate cyclase (SGC)-cyclic guanosine monophosphate (cGMP) signaling pathway both in vitro and in vivo. This orchestrated cascade culminates in the facilitation of angiogenesis and osteogenesis, thus expediting the reparative processes in bone defects. In a nutshell, the NO release-responsive system elucidated in this study presents a pioneering avenue for refining the bone tissue microenvironment and fostering enhanced bone regeneration.

New Therapeutics for Heart Failure Worsening: Focus on Vericiguat.

Heart failure (HF) is a syndrome characterized by signs and symptoms resulting from structural or functional cardiac abnormalities, confirmed by elevated natriuretic peptides or evidence of congestion. HF patients are classified according to left ventricular ejection fraction (LVEF). Worsening HF (WHF) is associated with increased short- and long-term mortality, re-hospitalization, and healthcare costs. The standard treatment of HF includes angiotensin-converting enzyme inhibitors, angiotensin receptor-neprilysin inhibitors, mineralocorticoid-receptor antagonists, beta-blockers, and sodium-glucose-co-transporter 2 inhibitors. To manage systolic HF by reducing mortality and hospitalizations in patients experiencing WHF, treatment with vericiguat, a direct stimulator of soluble guanylate cyclase (sGC), is indicated. This drug acts by stimulating sGC enzymes, part of the nitric oxide (NO)-sGC-cyclic guanosine monophosphate (cGMP) signaling pathway, regulating the cardiovascular system by catalyzing cGMP synthesis in response to NO. cGMP acts as a second messenger, triggering various cellular effects. Deficiencies in cGMP production, often due to low NO availability, are implicated in cardiovascular diseases. Vericiguat stimulates sGC directly, bypassing the need for a functional NO-sGC-cGMP axis, thus preventing myocardial and vascular dysfunction associated with decreased sGC activity in heart failure. Approved by the FDA in 2021, vericiguat administration should be considered, in addition to the four pillars of reduced EF (HFrEF) therapy, in symptomatic patients with LVEF < 45% following a worsening event. Cardiac rehabilitation represents an ideal setting where there is more time to implement therapy with vericiguat and incorporate a greater number of medications for the management of these patients. This review covers vericiguat's metabolism, molecular mechanisms, and drug-drug interactions.

A 2-week treatment with 5-azacytidine improved the hypercontractility state in prostate from obese mice: Role of the nitric oxide-cyclic guanosine monophosphate signalling pathway.

Benign prostatic hyperplasia (BPH) is characterised by increases in prostate volume and contraction. Downregulation of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signalling pathway contributes to prostate dysfunctions. Previous studies in cancer cells or vessels have shown that the epigenetic mechanisms control the gene and protein expression of the enzymes involved in the production of NO and cGMP. This study is aimed to evaluate the effect of a 2-week treatment of 5-azacytidine (5-AZA), a DNA-methyltransferase inhibitor, in the prostate function of mice fed with a high-fat diet. Functional, histological, biochemical and molecular assays were carried out. Obese mice presented greater prostate weight, α-actin expression and contractile response induced by the α-1adrenoceptors agonist. The relaxation induced by the NO-donor and the protein expression of endothelial nitric oxide synthase (eNOS) and soluble guanylate cyclase (sGC) were significantly decreased in the prostate of obese mice. The treatment with 5-AZA reverted the higher expression of α-actin, reduced the hypercontractility state of the prostate and increased the expression of eNOS and sGC and intraprostatic levels of cGMP. When prostates from obese mice treated with 5-AZA were incubated in vitro with inhibitors of the NOS or sGC, the inhibitory effect of 5-AZA was reverted, therefore, showing the involvement of NO and cGMP. In conclusion, our study paves the way to develop or repurpose therapies that recover the expression of eNOS and sGC and, hence, to improve prostate function in BPH.

The role of single-cell RNA sequencing in cardiac tumour - a case report

A 65-year-old woman presented to our hospital with 5 days of chest tightness, dyspnoea, and lower abdominal distension. Echocardiography revealed a mass in the right atrium. An emergency operation was carried out to prevent tumour shedding. The patient was discharged on the 4th day of tumour resection, without any complications At the 18 months follow-up, she suffered from kidney and lung tumours. She refused any treatment and passed away. scRNA-seq was applied to analyse the nature of the tumour. The cellular components of benign tumours include chondrocytes, smooth muscle cells, fibroblasts, mesenchymal stromal cells, and osteoblasts. Additionally, the cyclic guanosine monophosphate (cGMP-PKG) signalling pathway, transcriptional misregulation in cancer, and the p53 signalling pathway may be related to the growth of this tumour. scRNA-seq is a good approach to analyse growth patterns of cardiac tumours and helpful for distinguishing the nature of the tumour. Keywords: Sequence Analysis, RNA, Cardiac tumour.

Formaldehyde induced the cardiac damage by regulating the NO/cGMP signaling pathway and L-Ca2+ channels.

Formaldehyde (FA) is a common environmental pollutant that has been found to cause negative cardiovascular effects, however, the toxicological mechanism is not well understood. In this study, we investigated the molecular effects of the Nitric Oxide (NO)/cyclic Guanosine Monophosphate (cGMP) signaling pathway and L-type calcium (L-Ca2+) channels in rat hearts. We designed the short-term FA exposure on the rat heart in different concentrations (0, 0.5, 3, 18 mg/m3). After 7 days of exposure, the rats were sacrificed and the rat tissues were removed for various experiments. Our experimental data showed that FA resulted in the upregulation NO and cGMP, especially at 18 mg/m3. Further, when exposed to high concentrations of FA, Cav1.2 and Cav1.3 expression decreased. We conclude that the NO/cGMP signaling pathway and downstream related channels can be regulated by increasing the production of NO in the low concentration group of FA. High concentration FA directly regulates L-Ca22+ channels. This study suggests that FA damages the function of the cardiovascular system by regulating the NO/cGMP signaling pathway and L-Ca2+ channels.

Roles of Protein S-Nitrosylation in Endothelial Homeostasis and Dysfunction.

Significance: Nitric oxide (NO) plays several distinct roles in endothelial homeostasis. Except for activating the guanylyl cyclase enzyme-dependent cyclic guanosine monophosphate signaling pathway, NO can bind reactive cysteine residues in target proteins, a process known as S-nitrosylation (SNO). SNO is proposed to explain the multiple biological functions of NO in the endothelium. Investigating the targets and mechanism of protein SNO in endothelial cells (ECs) can provide new strategies for treating endothelial dysfunction-related diseases. Recent Advances: In response to different environments, proteomics has identified multiple SNO targets in ECs. Functional studies confirm that SNO regulates NO bioavailability, inflammation, permeability, oxidative stress, mitochondrial function, and insulin sensitivity in ECs. It also influences EC proliferation, migration, apoptosis, and transdifferentiation. Critical Issues: Single-cell transcriptomic analysis of ECs isolated from different mouse tissues showed heterogeneous gene signatures. However, litter research focuses on the heterogeneous properties of SNO proteins in ECs derived from different tissues. Although metabolism reprogramming plays a vital role in endothelial functions, little is known about how protein SNO regulates metabolism reprogramming in ECs. Future Directions: Precisely deciphering the effects of protein SNO in ECs isolated from different tissues under different conditions is necessary to further characterize the relationship between protein SNO and endothelial dysfunction-related diseases. In addition, identifying SNO targets that can influence endothelial metabolic reprogramming and the underlying mechanism can offer new views on the crosstalk between metabolism and post-translational protein modification. Antioxid. Redox Signal. 40, 186-205.

The bitter taste receptor (TAS2R) agonist denatonium promotes a strong relaxation of rat corpus cavernosum

Bitter taste receptors (TAS2R) are found in numerous extra-oral tissues, including smooth muscle (SM) cells in both vascular and visceral tissues. Upon activation, TAS2R stimulate the relaxation of the SM. Nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway is involved in penile erection, and type 5 phosphodiesterase (PDE5) inhibitors, a cGMP-specific hydrolase are used as first-line treatments for erectile dysfunction (ED). Nevertheless, PDE5 inhibitors are ineffective in a considerable number of patients, prompting research into alternative pharmacological targets for ED. Since TAS2R agonists regulate SM contractility, this study investigates the role of TAS2Rs in rat corpus cavernosum (CC). We performed immunohistochemistry to detect TAS2R10, isometric force recordings for TAS2R agonists denatonium and chloroquine, the slow-release H2S donor GYY 4137, the NO donor SNAP, the β-adrenoceptor agonist isoproterenol and electrical field stimulation (EFS), as well as measurement of endogenous hydrogen sulfide (H2S) production. The immunofluorescence staining indicated that TAS2R10 was broadly expressed in the CC SM and to some extent in the nerve fibers. Denatonium, chloroquine, SNAP, and isoproterenol cause potent dose-dependent SM relaxations. H2S production was decreased by NO and H2S synthase inhibitors, while it was enhanced by denatonium. In addition, denatonium increased the relaxations induced by GYY 4137 and SNAP but failed to modify EFS- and isoproterenol-induced responses. These results suggest neuronal and SM TAS2R10 expression in the rat CC, where denatonium induces a strong SM relaxation per se and promotes the H2S- and NO-mediated inhibitory gaseous neurotransmission. Thus, TAS2R10 might represent a valuable therapeutic target in ED.

Nitric oxide: an old drug but with new horizons in ophthalmology-a narrative review.

Based on basic knowledge and prior research on nitric oxide (NO), the potential of NO for treating eye diseases is reviewed, and the possibility of NO-based eye drops in clinical practice and the future potential of NO in ophthalmology are discussed. A PubMed search was performed for English-language original reports and reviews using the following key words: nitric oxide, eye, ocular, and drug. NO is synthesized in the human body by NO synthase (NOS) from L-arginine or through enzyme-dependent reduction of dietary nitrate. Three types of NOS (eNOS, nNOS, and iNOS) are abundantly expressed in the eye under normal physiologic or pathologic conditions. The biological effect of NO in the eye is dose dependent. Low intraocular NO concentrations, produced by eNOS or nNOS, have various cellular effects, including vasodilation, intraocular pressure (IOP) regulation, and neuroprotection. iNOS induced under pathologic ocular conditions produces high NO concentrations in the local environment and mediates tissue inflammation, ocular cell apoptosis, and neurodegeneration. In particular, increased iNOS has been reported in glaucoma and retinal ischemic or degenerative diseases. NO plays a vital role in ocular injury. NO can facilitate ocular surface wound healing while eradicating pathogens such as bacteria and Acanthamoeba in chemical burns or infectious keratitis. Furthermore, NO has antifibrotic activity via the cyclic guanosine monophosphate (cGMP) signaling pathway. NO causes smooth muscle relaxation, which can be used to inhibit myopia progression in children. NO can be a stem cell modulator and may help in treating ocular stem cell disorders. Because of its diverse biologic effects, NO can be a key player in regulating ocular inflammation in various ocular diseases, aiding ocular surface wound healing, controlling IOP in glaucoma, alleviating retinal disease, and suppressing myopia progression. Although there remain limitations to the effective use of highly unstable state, gaseous NO, the role of NO in the field of ophthalmology can be greatly expanded through the development of novel NO donors and effective delivery platforms.

CGMP signaling: a potential therapeutic target for neurodegeneration in glaucoma?

cGMP signaling: a potential therapeutic target for neurodegeneration in glaucoma?

Design, synthesis, and biological evaluation of novel NO-releasing 4-chromanone derivatives as potential vasodilator agents.

The nitric oxide/cyclic guanosine monophosphate (NO/cGMP) signaling pathway is an effective mechanism involved in the treatment of hypertension. In our search for potential antihypertensive agents, a series of novel NO-donor derivatives of the 4-chromanone skeleton were designed and synthesized by coupling furoxans or nitrooxy NO-donor moieties. All derivatives showed enhanced nitric oxide releasing capacity and vasodilator activity with EC50 values ranging from 0.0215 μM to 1.46 μM, obviously superior to those of precursor 3. These biological evaluations indicated that all compounds displayed an important vasorelaxant effect, and several compounds (9c, 14b, 14c, 14d) presented good vasodilator activity, with 14c being the best. Furthermore, molecular modeling studies revealed that compound 14c occupied the pocket well with the phosphodiesterase 5 domain in a favorable conformation. In conclusion, we observed that these novel compounds can act as structural templates for the design and subsequent development of new vasodilators and antihypertensive drugs.

Vericiguat in Heart Failure: Characteristics, Scientific Evidence and Potential Clinical Applications.

Despite recent advances in heart failure (HF) management, the risk of death and hospitalizations remains high in the long term. HF is characterized by endothelial dysfunction, inflammation and increased oxidative stress, due to a reduction in the activity of the nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signaling pathway. All these factors contribute to direct damage at the myocardial, vascular and renal level. Vericiguat restores the deficiency in this signaling pathway, through stimulation and activation of sGC, aiming to increase cGMP levels, with a reduction in HF-related oxidative stress and endothelial dysfunction. Two main clinical trials were developed in this setting: the SOCRATES-REDUCED phase II study and the VICTORIA phase III study. They found that vericiguat is safe, well tolerated and effective with an absolute event-rate reduction in patients affected by HF with reduced ejection fraction (HFrEF) and recent cardiac decompensation. In patients with HF with preserved ejection fraction (HfpEF), the SOCRATES-PRESERVED trial demonstrated an improvement in quality of life and health status, but the proven beneficial effects with vericiguat are still limited. Further studies are needed to correctly define the role of this drug in heart failure syndromes. Our paper reviews the potential applications and pharmacological characteristics of vericiguat in HFrEF and HFpEF.

An auto-inhibited state of protein kinase G and implications for selective activation.

Cyclic GMP-dependent protein kinases (PKGs) are key mediators of the nitric oxide/cyclic guanosine monophosphate (cGMP) signaling pathway that regulates biological functions as diverse as smooth muscle contraction, cardiac function, and axon guidance. Understanding how cGMP differentially triggers mammalian PKG isoforms could lead to new therapeutics that inhibit or activate PKGs, complementing drugs that target nitric oxide synthases and cyclic nucleotide phosphodiesterases in this signaling axis. Alternate splicing of PRKG1 transcripts confers distinct leucine zippers, linkers, and auto-inhibitory (AI) pseudo-substrate sequences to PKG Iα and Iβ that result in isoform-specific activation properties, but the mechanism of enzyme auto-inhibition and its alleviation by cGMP is not well understood. Here, we present a crystal structure of PKG Iβ in which the AI sequence and the cyclic nucleotide-binding (CNB) domains are bound to the catalytic domain, providing a snapshot of the auto-inhibited state. Specific contacts between the PKG Iβ AI sequence and the enzyme active site help explain isoform-specific activation constants and the effects of phosphorylation in the linker. We also present a crystal structure of a PKG I CNB domain with an activating mutation linked to Thoracic Aortic Aneurysms and Dissections. Similarity of this structure to wildtype cGMP-bound domains and differences with the auto-inhibited enzyme provide a mechanistic basis for constitutive activation. We show that PKG Iβ auto-inhibition is mediated by contacts within each monomer of the native full-length dimeric protein, and using the available structural and biochemical data we develop a model for the regulation and cooperative activation of PKGs.

Sodium Ferulate Inhibits Rat Cardiomyocyte Hypertrophy Induced by Angiotensin II Through Enhancement of Endothelial Nitric Oxide Synthase/Nitric Oxide/Cyclic Guanosine Monophosphate Signaling Pathway.

Sodium ferulate (SF) is the sodium salt of ferulic acid, which is one of the effective components of Angelica sinensis and Lignsticum chuanxiong , and plays an important role in protecting the cardiovascular system. In this study, myocardial hypertrophy was induced by angiotensin II 0.1 μmol/L in neonatal Sprague-Dawley rat ventricular myocytes. Nine groups were designed, that is, normal, normal administration, model, L-arginine (L-arg 1000 μmol/L), SF (50, 100, 200 μmol/L) group, and N G -nitro-L-arg-methyl ester 1500 μmol/L combined with SF 200 μmol/L or L-arg 1000 μmol/L group, respectively. Cardiomyocyte hypertrophy was confirmed by observing histological changes and measurements of cell diameter, protein content and atrial natriuretic factor, and β-myosin heavy chain levels of the cells. Notably, SF could inhibit significantly myocardial hypertrophy of neonatal rat cardiomyocytes in a concentration-dependent manner without producing cytotoxicity, and the levels of nitric oxide, NO synthase (NOS), endothelial NOS, and cyclic guanosine monophosphate were increased, but the level of cyclic adenosine monophosphate was decreased in cardiomyocytes. Simultaneously, levels of protein kinase C beta, Raf-1, and extracellular regulated protein kinase 1/2 (ERK1/2) were downregulated, whereas levels of mitogen-activated protein kinase phosphatase-1 were significantly upregulated. All the beneficial effects of SF were blunted by N G -nitro-L-arg-methyl ester. Overall, these findings reveal that SF can inhibit angiotensin II-induced myocardial hypertrophy of neonatal rat cardiomyocytes, which is closely related to activation of endothelial NOS/NO/cyclic guanosine monophosphate, and inhibition of protein kinase C and mitogen-activated protein kinase signaling pathways.

Effect of moxibustion on inflammatory pain and N-methyl-D aspartic acid receptor-nitric oxide-cyclic GMP pathway in spinal cord of adjuvant arthritis rats

To observe the effect of moxibustion on pain and N-methyl-D aspartic acid receptor/nitric oxide/cyclic guanosine monophosphate (NMDA-NO-cGMP) signaling pathway in the spinal cord of rats with adjuvant arthritis (AA), so as to explore its underlying mechanisms in relieving inflammatory pain of rheumatoid arthritis (RA). SD rats were randomly divided into normal, model, moxibustion (Moxi), Moxi +NMDA receptor antagonist AP-5 (Moxi+AP-5) and Moxi +NMDA receptor agonist (NMDA) groups, with 20 rats in each group. The AA model was established by placing the rats in a wind, cold and damp environment for 12 h, once daily for 20 days and by injection of complete Freund's adjuvant into the right hind paw. Rats of the three Moxi groups received ignited moxa-stick stimulation of "Zusanli"(ST36) and "Shenshu"(BL23) alternately for 20 min, once a day for 15 days. The Moxi + AP-5 group and Moxi +NMDA group received intraperitoneal injection of AP-5 (0.7 mg·kg-1·d-1) and NMDA (5 mg·kg-1·d-1), respectively, once a day, for a total of 15 days. Mechanical pain thres-hold (MPT) was measured before and after modeling and interventions. The spinal cord tissue was sampled for detecting the expression of iNOS mRNA and protein, content of cGMP and NO, and the activity of NOS by using fluorescence quantitative PCR, Western blot, ELISA,nitrate reductase method and colorimetric method, respectively. Before modeling, there was no significant difference in MPT among all the 5 groups (P>0.05). After modeling, the MPT was remarkably decreased (P<0.01), the expression levels of iNOS mRNA and protein,the contents of cGMP and NO, the activity of NOS were significantly increased in the model group relevant to the normal group (P<0.01). After the interventions, the MPT was obviously increased (P<0.01), while the expression levels of iNOS mRNA and protein, the contents of cGMP and NO, the activity of NOS were significantly down-regulated in the Moxi, Moxi-AP-5 and Moxi+NMDA groups (P<0.05, P<0.01). The effect of Moxi+AP-5 group was significantly superior to that of Moxi group in raising MPT and down-regulating the expression levels of iNOS mRNA and protein, and the content of NO (P<0.05, P<0.01). The effect of Moxi+NMDA group was obviously inferior to that of Moxi group in up-regulating MPT and down-regulating the levels of iNOS mRNA and protein, and the contents of cGMP and NO, and the activity of NOS (P<0.01), suggesting a reduction of the therapeutic effects in raising MPT and down-regulating expression of iNOS mRNA and protein after administration of AP-5. Moxibustion can relieve RA inflammatory pain in AA rats, which may be related to its function in down-regulating the NMDA/NO/cGMP signaling pathway in the spinal cord.

Electrosprayed Regeneration‐Enhancer‐Element Microspheres Power Osteogenesis and Angiogenesis Coupling

Electrosprayed microspheres for bone regeneration are conventionally restricted by the lack of osteogenic modulation for both encapsulated stem cells and surrounding cells at the defect site. Here, sodium alginate microspheres encapsulating L-arginine doped hydroxyapatite nanoparticles (Arg/HA NPs) and bone mesenchymal stem cells (BMSCs) as regeneration-enhancer-element reservoirs (Arg/HA-SA@BMSC) for bone healing are electrosprayed. The Arg/HA NPs serve as a container of L-arginine and Ca2+ and the BMSCs inside the microspheres metabolize the released L-arginine into bioactive gas nitric oxide (NO) in the presence of Ca2+ to activate the nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway. Meanwhile, the generated NO diffuses out of the microspheres together with the Ca2+ and L-arginine as exterior enhancers to promote the osteogenesis-angiogenesis coupling of surrounding BMSCs and endothelial cells (ECs) at the bone defect site, generating an internal/external modulation loop between the encapsulated cells and surrounding native cells. It is demonstrated that such regeneration-enhancer-element reservoirs could effectively increase the bone tissue formation and neovasculature using rat calvarial defect models. It is envisioned that the microsphere system could streamline vascularized bone regeneration therapy as a high throughput, minimally invasive yet highly effective strategy to accelerate bone healing.

Effects of soluble guanylate cyclase stimulator on renal function in ZSF-1 model of diabetic nephropathy.

BackgroundDiabetic nephropathy is associated with endothelial dysfunction and oxidative stress, in which the nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate (NO-sGC-cGMP) signaling pathway is impaired. We hypothesize that sGC stimulator Compound 1 can enhance NO signaling, reduce proteinuria in a diabetic nephropathy preclinical model with diminished NO bioavailability and increased oxidized sGC. Therefore, we evaluated the effect of sGC stimulator Compound 1 on the renal effect in obese ZSF1 (ZSF1 OB) rats.Materials and methodsThe sGC stimulator Compound 1, the standard of care agent Enalapril, and a combination of Compound 1 and Enalapril were administered chronically to obese ZSF1 rats for 6 months. Mean arterial pressure, heart rate, creatinine clearance for glomerular filtration rate (eGFR), urinary protein excretion to creatinine ratio (UPCR), and urinary albumin excretion ratio (UACR) were determined during the study. The histopathology of glomerular and interstitial lesions was assessed at the completion of the study.ResultsWhile both Compound 1 and Enalapril significantly reduced blood pressure, the combination of Compound 1 and Enalapril normalized blood pressure levels. Compound 1 improved eGFR and reduced UPCR and UACR. A combination of Enalapril and Compound 1 resulted in a marked reduction in UPCR and UACR and improved GFR.ConclusionThe sGC stimulator Compound 1 as a monotherapy slowed renal disease progression, and a combination of the sGC stimulator with Enalapril provided greater renal protection in a rodent model of diabetic nephropathy.

Pseudomonas aeruginosa biofilm dispersion by the mouse antimicrobial peptide CRAMP

Pseudomonas aeruginosa (P. aeruginosa) is a known bacterium that produces biofilms and causes severe infection. Furthermore, P. aeruginosa biofilms are extremely difficult to eradicate, leading to the development of chronic and antibiotic-resistant infections. Our previous study showed that a cathelicidin-related antimicrobial peptide (CRAMP) inhibits the formation of P. aeruginosa biofilms and markedly reduces the biomass of preformed biofilms, while the mechanism of eradicating bacterial biofilms remains elusive. Therefore, in this study, the potential mechanism by which CRAMP eradicates P. aeruginosa biofilms was investigated through an integrative analysis of transcriptomic, proteomic, and metabolomic data. The omics data revealed CRAMP functioned against P. aeruginosa biofilms by different pathways, including the Pseudomonas quinolone signal (PQS) system, cyclic dimeric guanosine monophosphate (c-di-GMP) signalling pathway, and synthesis pathways of exopolysaccharides and rhamnolipid. Moreover, a total of 2914 differential transcripts, 785 differential proteins, and 280 differential metabolites were identified. A series of phenotypic validation tests demonstrated that CRAMP reduced the c-di-GMP level with a decrease in exopolysaccharides, especially alginate, in P. aeruginosa PAO1 biofilm cells, improved bacterial flagellar motility, and increased the rhamnolipid content, contributing to the dispersion of biofilms. Our study provides new insight into the development of CRAMP as a potentially effective antibiofilm dispersant.

Nitric oxide — soluble guanylate cyclase — cyclic guanosine monophosphate signaling pathway in the pathogenesis of heart failure and search for novel therapeutic targets

Heart failure is a severe disease with an unfavorable prognosis, which requires intensification of therapy and the search for novel approaches to treatment. In this review, the physiological significance of soluble guanylate cyclase-related signaling pathway, reasons for decrease in its activity in heart failure and possible consequences are discussed. Pharmacological methods of stimulating the production of cyclic guanosine monophosphate using drugs with different mechanisms of action are considered. Data from clinical studies regarding their effectiveness and safety are presented. A promising approach is stimulation of soluble guanylate cyclase, which showed beneficial effects in preclinical studies, as well as in the recently completed phase III VICTORIA study.