Regulation of pleiotropic physiological roles of nitric oxide signaling

Amaryllidaceae alkaloids with nitric oxide inhibitory activity from the leaves of Crinum asiaticum L. var. asiaticum

Forty-two Amaryllidaceae alkaloids, including eleven previously undescribed alkaloids, crinasiaticines C-M, and three undescribed naturally occurring alkaloids, (+)-dihydroepivittatine, (+)-dihydrovittatine and (+)-dihydrohamayne, were isolated from the leaves of Crinum asiaticum L. var. asiaticum. Their structures and configurations were elucidated using NMR and MS spectroscopic techniques, along with the comparison of experimental electronic circular dichroism spectra to calculated data. The anti-inflammatory activity against nitric oxide (NO) production in lipopolysaccharide-stimulated RAW264.7 cells was evaluated for most of the isolated alkaloids. Compounds 39, 21, 22, and 35 exhibited considerable NO inhibitory activity, with IC50 values of 2.5-2.6 μM, compared to positive control dexamethasone (IC50 2.7 μM). However, these compounds demonstrated cytotoxic effects on cells. Compound 15 also possessed the highest selectivity index of 22.5 with minimal cytotoxicity.

Choroid plexus organoids reveal mechanisms of Streptococcus suis translocation at the blood-cerebrospinal fluid barrier

Streptococcus suis is a globally emerging zoonotic pathogen that can cause invasive disease commonly associated with meningitis in pigs and humans. To cause meningitis, S. suis must invade the central nervous system (CNS) by crossing the neurovascular unit, also known as the blood-brain barrier (BBB), or vascularized choroid plexus (ChP) epithelium known as the blood-cerebrospinal fluid barrier (BCSFB). Recently developed ChP organoids have been shown to accurately replicate the cytoarchitecture and physiological functions of the ChP epithelium in vivo. Here, we used human induced pluripotent stem cells (iPSC)-derived ChP organoids as an in vitro model to investigate S. suis interaction and infection at the BCSFB. Our study revealed that S. suis is capable of translocating across the epithelium of ChP organoids without causing significant cell death or compromising the barrier integrity. Plasminogen (Plg) binding to S. suis in the presence of tissue plasminogen activator (tPA), which converts immobilized Plg to plasmin (Pln), significantly increased the basolateral to apical translocation across ChP organoids into the CSF-like fluid in the lumen. S. suis was able to replicate at the same rate in CSF and laboratory S. suis culture medium but reached a lower final density. The analysis of transcriptomes in ChP organoids after S. suis infection indicated inflammatory responses, while the addition of Plg further suggested extracellular matrix (ECM) remodeling. To our knowledge, this is the first study using ChP organoids to investigate bacterial infection of the BCSFB. Our findings highlight the potential of ChP organoids as a valuable tool for studying the mechanisms of bacterial interaction and infection of the human ChP in vitro.

Nitric Oxide in Parkinson's Disease: The Potential Role of Dietary Nitrate in Enhancing Cognitive and Motor Health via the Nitrate-Nitrite-Nitric Oxide Pathway

BACKGROUND/OBJECTIVES

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor symptoms such as tremor, rigidity, and bradykinesia. The pathological hallmarks of PD include Lewy bodies and mechanisms like oxidative/nitrosative stress, chronic inflammation, and mitochondrial dysfunction. Nitric oxide (NO), produced by nitric oxide synthase (NOS) isoforms, plays a dual role in neuroprotection and neurodegeneration. Excessive NO production exacerbates neuroinflammation and oxidative/nitrosative damage, contributing to dopaminergic cell death. This review explores NO's role in PD pathogenesis and investigates dietary nitrate as a therapeutic strategy to regulate NO levels.

METHODS

A literature review of studies addressing the role of NO in PD was conducted using major scientific databases, including PubMed, Scopus, and Web of Science, using keywords such as "nitric oxide", "NOSs", "Parkinson's disease", and "nitrate neuroprotection in PD". Studies on nitrate metabolism via the nitrate-nitrite-NO pathway and its effects on PD hallmarks were analyzed. Studies regarding the role of nitrosamine formation in PD, which are mainly formed during the nitrification process of amines (nitrogen-containing compounds), often due to chemical reactions in the presence of nitrite or nitrate, were also examined. In particular, nitrate has been shown to induce oxidative stress, affect the mitochondrial function, and contribute to inflammatory phenomena in the brain, another factor closely related to the pathogenesis of PD.

RESULTS

Excessive NO production, particularly from iNOS and nNOS, was strongly associated with neuroinflammation and oxidative/nitrosative stress, amplifying neuronal damage in PD. Dietary nitrate was shown to enhance NO bioavailability through the nitrate-nitrite-NO pathway, mitigating inflammation and oxidative/nitrosative damage.

CONCLUSIONS

Dysregulated NO production contributes significantly to PD progression via inflammatory and oxidative/nitrosative pathways. Dietary nitrate, by modulating NO levels, offers a promising therapeutic strategy to counteract these pathological mechanisms. Further clinical trials are warranted to establish its efficacy and optimize its use in PD management.

Metabolic Responses to Redox Stress in Vascular Cells

Significance: Redox stress underlies numerous vascular disease mechanisms. Metabolic adaptability is essential for vascular cells to preserve energy and redox homeostasis. Recent Advances: Single-cell technologies and multiomic studies demonstrate significant metabolic heterogeneity among vascular cells in health and disease. Increasing evidence shows that reductive or oxidative stress can induce metabolic reprogramming of vascular cells. A recent example is intracellular L-2-hydroxyglutarate accumulation in response to hypoxic reductive stress, which attenuates the glucose flux through glycolysis and mitochondrial respiration in pulmonary vascular cells and provides protection against further reductive stress. Critical Issues: Regulation of cellular redox homeostasis is highly compartmentalized and complex. Vascular cells rely on multiple metabolic pathways, but the precise connectivity among these pathways and their regulatory mechanisms is only partially defined. There is also a critical need to understand better the cross-regulatory mechanisms between the redox system and metabolic pathways as perturbations in either systems or their cross talk can be detrimental. Future Directions: Future studies are needed to define further how multiple metabolic pathways are wired in vascular cells individually and as a network of closely intertwined processes given that a perturbation in one metabolic compartment often affects others. There also needs to be a comprehensive understanding of how different types of redox perturbations are sensed by and regulate different cellular metabolic pathways with specific attention to subcellular compartmentalization. Lastly, integration of dynamic changes occurring in multiple metabolic pathways and their cross talk with the redox system is an important goal in this multiomics era. Antioxid. Redox Signal. 41,793-817.

Customized A-D-A type molecule to construct a nitric oxide nanogenerator with enhanced antibacterial activity for infected wound healing

Bacterial infections pose an increasingly serious threat to global health due to the development of drug-resistant strains. Developing a method to efficiently kill bacteria and promote tissue repair is imperative to decrease the damage from bacterial infection, especially infected wounds. Herein, a biofriendly and light-controlled nitric oxide (NO) generator HFB with simultaneous bacterial killing and wound repair properties is reported based on a tailored light-responsive molecule F(EIBC)2. HFB demonstrates an appropriate photothermal conversion efficiency of 33.4% and type I reactive oxygen species (˙OH and H2O2) generation capability to simultaneously trigger NO generation and potently kill bacteria. Furthermore, HFB can effectively eradicate mature bacterial biofilms with the aid of favorable permeability of NO. Additionally, HFB effectively eradicates Staphylococcus aureus in infected wounds of living mice and accelerates healing via NO-induced angiogenesis and collagen deposition. Owing to the encapsulated human serum albumin (HSA), heavy metal-free feature, and synergistic killing mechanism, HFB exhibits good biosafety to surrounding tissue and major organs. This work provides a novel dual-functional photo-responsive molecule and a potential light-controlled release platform for the treatment of bacterial infections.

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.

Pleiotropic effects of nitric oxide sustained-release system for peripheral nerve repair

The regenerative microenvironment after peripheral nerve injury is imbalanced and difficult to rebalance, which is mainly affected by inflammation, oxidative stress, and inadequate blood supply. The difficulty in remodeling the nerve regeneration microenvironment is the main reason for slow nerve regeneration. Traditional drug treatments have certain limitations, such as difficulty in penetrating the blood-nerve barrier and lack of pleiotropic effects. Therefore, there is an urgent need to build multifunctional nerve grafts that can effectively regulate the regenerative microenvironment and promote nerve regeneration. Nitric oxide (NO), a highly effective gas transmitter with diatomic radicals, is an important regulator of axonal growth and migration, synaptic plasticity, proliferation of neural precursor cells, and neuronal survival. Moreover, NO provides potential anti-inflammation, anti-oxidation, and blood vessel promotion applications. However, excess NO may cause cell death and neuroinflammatory cell damage. The prerequisite for NO treatment of peripheral nerve injury is that it is gradually released over time. In this study, we constructed an injectable NO slow-release system with two main components, including macromolecular NO donor nanoparticles (mPEG-P(MSNO-EG) nanoparticles, NO-NPs) and a carrier for the nanoparticles, mPEG-PA-PP injectable temperature-sensitive hydrogel. Due to the multiple physiological regulation of NO and better physiological barrier penetration, the conduit effectively regulates the inflammatory response and oxidative stress of damaged peripheral nerves, promotes nerve vascularization, and nerve regeneration and docking, accelerating the nerve regeneration process. STATEMENT OF SIGNIFICANCE: The slow regeneration speed of peripheral nerves is mainly due to the destruction of the regeneration microenvironment. Neural conduits with drug delivery capabilities have the potential to improve the microenvironment of nerve regeneration. However, traditional drugs are hindered by the blood nerve barrier and cannot effectively target the injured area. NO, an endogenous gas signaling molecule, can freely cross the blood nerve barrier and act on target cells. However, excessive NO can lead to cell apoptosis. In this study, a NO sustained-release system was constructed to regulate the microenvironment of nerve regeneration through various pathways and promote nerve regeneration.

Probing calmodulin-NO synthase interactions via site-specific infrared spectroscopy: an introductory investigation

Calmodulin (CaM) binds to a linker between the oxygenase and reductase domains of nitric oxide synthase (NOS) to regulate the functional conformational dynamics. Specific residues on the interdomain interface guide the domain-domain docking to facilitate the electron transfer in NOS. Notably, the docking interface between CaM and the heme-containing oxygenase domain of NOS is isoform specific, which is only beginning to be investigated. Toward advancing understanding of the distinct CaM-NOS docking interactions by infrared spectroscopy, we introduced a cyano-group as frequency-resolved vibrational probe into CaM individually and when associated with full-length and a bi-domain oxygenase/FMN construct of the inducible NOS isoform (iNOS). Site-specific, selective labeling with p-cyano-L-phenylalanine (CNF) by amber suppression of CaM bound to the iNOS has been accomplished by protein coexpression due to the instability of recombinant iNOS protein alone. We introduced CNF at residue 108, which is at the putative CaM-heme (NOS) docking interface. CNF was also introduced at residue 29, which is distant from the docking interface. FT IR data show that the 108 site is sensitive to CaM-NOS complex formation, while insensitivity to its association with the iNOS protein or peptide was observed for the 29 site. Moreover, narrowing of the IR bands at residue 108 suggests the C≡N probe experiences a more limited distribution of environments, indicating side chain restriction apparent for the complex with iNOS. This initial work sets the stage for residue-specific characterizations of structural dynamics of the docked states of NOS proteins.

Chemical Composition and Biological Activities of the Essential Oil from Citrus reticulata Blanco Peels Collected from Agrowastes

Citrus fruits have a thick outer coat which is often discarded due to its low economic value and usually contributes to the waste. So this work focused on exploring the potential pharmacological properties of the discarded citrus peels. In the present study, we extracted the essential oil from peel wastes of Citrus reticulata Blanco (CREO) from the local market. The antioxidant, antibacterial, and anticancer properties of essential oil were evaluated. The CREO exhibited a strong antioxidant property with DPPH radical scavenging, ABTS radical scavenging, H2 O2 radical scavenging, Ferric reducing antioxidant power and for Lipid peroxidation inhibition respectively. Antibacterial properties of CREO was indicated against different pathogenic microbial strains like E. coli, P. aeruginosa, S. aureus, and S. enterica in terms of disc diffusion method and minimum inhibitory concentration (MIC). Further, anticancer properties studied on breast cancer cell lines MCF7 and MDA-MB-231 showed dose-dependent cytotoxicity with IC50 of 56.67±3.12 μg/mL and 76.44±2.53 μg/mL respectively. The GC-MS analysis of CREO revealed the presence of major compounds like S-limonene, α-pinene, α-myrcene, and cis-terpinene which might have played a significant role in strong antioxidant, antibacterial and anticancer properties. The study thus identified the potential health benefits of Citrus reticulata peel waste.

Structural perturbations induced by cumulative action of methylglyoxal and peroxynitrite on human fibrinogen: An in vitro and in silico approach

Methylglyoxal (MGO); a reducing sugar and a dicarbonyl; attaches to the biomolecules (proteins, lipids, and DNA) leading to glycation and accumulation of oxidative stress in cells and tissues. Superoxide anion formed under such conditions entraps free nitric oxide radical (NO) to form peroxynitrite (PON). Nitro-oxidative stress due to PON is well established. Human fibrinogen plays a key role in haemostasis and is a highly vulnerable target for oxidation. Modifications of fibrinogen can potentially disrupt its structure and function. Earlier evidence suggested that glycation and nitro-oxidation lead to protein aggregation by making it resistant to lysis. This study aims to reveal the structural perturbations on fibrinogen in the presence of MGO and PON synergistically. The in vitro glyco-nitro-oxidation of human fibrinogen by MGO and PON leads to substantial structural alterations, as evident by biophysical and biochemical studies. In-silico results revealed the formation of stable complexes. UV-visible, intrinsic fluorescence, and circular dichroism investigations confirmed the synergistic effect of MGO and PON caused micro-structural modifications leading to secondary structural alterations. AGEs formation in MGO-modified fibrinogen reduced the free lysine and free arginine residues which were quantified by TNBS and phenanthrenequinone assays. Enhanced oxidative status was confirmed by estimating carbonyl content. ANS fluorophore validated exposure of hydrophobic patches in modified protein and thioflavin-T showed maximum binding with synergistically modified fibrinogen, indicated the formation of β-sheet. Confocal and electron microscope results corroborated the formation of aggregates. This study, therefore, evaluated the impact of MGO and PON on the structural integrity, oxidative status and aggregate formation of fibrinogen that can aggravate metabolic complications.

Exposure to Intermittent Environmental Hypoxia Promotes Vascular Remodeling through Angiogenesis in the Liver of Largemouth Bass (Micropterus salmoides)

In this study, we explored the effects of 4 weeks of intermittent hypoxic exposure (IHE) on liver angiogenesis and related regulatory mechanisms in largemouth bass (Micropterus salmoides). The results indicated that the O2 tension for loss of equilibrium (LOE) decreased from 1.17 to 0.66 mg/L after 4 weeks of IHE. Meanwhile, the red blood cell (RBC) and hemoglobin concentrations significantly increased during IHE. Our investigation also found that the observed increase in angiogenesis was correlated with a high expression of related regulators, such as Jagged, phosphoinositide-3-kinase (PI3K), and mitogen-activated protein kinase (MAPK). After 4 weeks of IHE, the overexpression of factors related to angiogenesis processes mediated by HIF-independent pathways (such as nuclear factor kappa-B (NF-κB), NADPH oxidase 1 (NOX1), and interleukin 8 (IL8)) was correlated with the accumulation of lactic acid (LA) in the liver. The addition of cabozantinib, a specific inhibitor of VEGFR2, blocked the phosphorylation of VEGFR2 and downregulated the expression of downstream angiogenesis regulators in largemouth bass hepatocytes exposed to hypoxia for 4 h. These results suggested that IHE promoted liver vascular remodeling by the regulation of angiogenesis factors, presenting a potential mechanism for the improvement of hypoxia tolerance in largemouth bass.

Cancer Resistance Is Mediated by the Upregulation of Several Anti-Apoptotic Gene Products via the Inducible Nitric Oxide Synthase/Nitric Oxide Pathway: Therapeutic Implications

Significance: Several therapeutic strategies for cancer treatments have been developed with time, and significant milestones have been achieved recently. However, with these novel therapies, not all cancer types respond and in the responding cancer types only a subset is affected. The failure to respond is principally the result that these cancers develop several mechanisms of resistance. Thus, a focus of current research investigations is to unravel the various mechanisms that regulate resistance and identify suitable targets for new therapeutics. Recent Advances: Hence, many human cancer types have been reported to overexpress the inducible nitric oxide synthase (iNOS) and it has been suggested that iNOS/nitric oxide (NO) plays a pivotal role in the regulation of resistance. We have postulated that iNOS overexpression or NO regulates the overexpression of pivotal anti-apoptotic gene products such as B-cell lymphoma 2 (Bcl-2), B-cell lymphoma extra large (Bcl-xL), myeloid cell leukemia-1 (Mcl-1), and survivin. In this report, we describe the various mechanisms, transcriptional, post-transcriptional, and post-translational, by which iNOS/NO regulates the expression of the above anti-apoptotic gene products. Critical Issues: The iNOS/NO-mediated regulation of the four gene products is not the same with both specific and overlapping pathways. Our findings are, in large part, validated by bioinformatic analyses demonstrating, in several cancers, several direct correlations between the expression of iNOS and each of the four examined anti-apoptotic gene products. Future Directions: We have proposed that targeting iNOS may be highly efficient since it will result in the underexpression of multiple anti-apoptotic proteins and shifting the balance toward the proapoptotic gene products and reversal of resistance. Antioxid. Redox Signal. 39, 853-889.

Inhaled nitric oxide: can it serve as a savior for COVID-19 and related respiratory and cardiovascular diseases?

Nitric oxide (NO), as an important gaseous medium, plays a pivotal role in the human body, such as maintaining vascular homeostasis, regulating immune-inflammatory responses, inhibiting platelet aggregation, and inhibiting leukocyte adhesion. In recent years, the rapid prevalence of coronavirus disease 2019 (COVID-19) has greatly affected the daily lives and physical and mental health of people all over the world, and the therapeutic efficacy and resuscitation strategies for critically ill patients need to be further improved and perfected. Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator, and some studies have demonstrated its potential therapeutic use for COVID-19, severe respiratory distress syndrome, pulmonary infections, and pulmonary hypertension. In this article, we describe the biochemistry and basic characteristics of NO and discuss whether iNO can act as a "savior" for COVID-19 and related respiratory and cardiovascular disorders to exert a potent clinical protective effect.

Genetic Modulation of HPV Infection and Cervical Lesions: Role of Oxidative Stress-Related Genes

Human papillomavirus (HPV) infection is a necessary but not sufficient factor for the development of invasive cervical cancer (ICC) and high-grade intraepithelial lesion (HSIL). Oxidative stress is known to play a crucial role in HPV infection and carcinogenesis. In this study, we comprehensively investigate the modulation of HPV infection, HSIL and ICC, and ICC through an exploration of oxidative stress-related genes: CβS, MTHFR, NOS3, ACE1, CYBA, HAP, ACP1, GSTT1, GSTM1, and CYP1A1. Notably, the ACE1 gene emerges as a prominent factor with the presence of the I allele offering protection against HPV infection. The association of NOS3 with HPV infection is perceived with the 4a allele showing a protective effect. The presence of the GSTT1 null mutant correlates with increased susceptibility to HPV infection, HSIL and ICC, and ICC. This study also uncovers intriguing epistatic interactions among some of the genes that further accentuate their roles in disease modulation. Indeed, the epistatic interactions between the BB genotype (ACP1) and DD genotype (ECA1) were shown to increase the risk of HPV infection, and the interaction between BB (ACP1) and 0.0 (GSTT1) was associated with HPV infection and cervical lesions. These findings underscore the pivotal role of four oxidative stress-related genes in HPV-associated cervical lesions and cancer development, enriching our clinical understanding of the genetic influences on disease manifestation. The awareness of these genetic variations holds potential clinical implications.

Swimming Exercise-Induced Improvements in Cardiorespiratory Fitness (CRF) are Caused by Nitric Oxide Functional Adaptations in the Oxygen Transport System

Cardiorespiratory fitness (CRF) is associated with referring to enhance oxygen transport capacity to respiratory systems and increasing oxygen transport circulatory to skeletal muscle to produce energy. The aim of this report on the health-related CRF in the oxygen transport system-mediated physiological nitric oxide (NO) functional adaptations. Therefore, we want to know that swimming exercise-induced improvements in CRF resulted in increased oxygen transport capacity during physical activity of the respiratory systems. Therefore, the oxygen circulatory transport system is related to NO signaling and has been associated with various pathophysiologic functions and neuronal activity. Besides mediating normal functions, NO is implicated in inflammation and hypertension disease states. Swimming exercise is a good way to increase the rate of metabolism. Swimming exercise improves heart rate and oxygen circulatory, and increases the rate of metabolism and burning of heat. In this context, this review summarizes the roles of NO in improvements in cardiorespiratory fitness.

Glyphosate induces autophagy in hepatic L8824 cell line through NO-mediated activation of RAS/RAF/MEK/ERK signaling pathway and energy metabolism disorders

Glyphosate is an herbicide commonly used worldwide, and its substantial use causes widespread pollution with runoff. However, research on glyphosate toxicity has mostly remained at the embryonic level and existing studies are limited. In the present study, we investigated whether glyphosate can induce autophagy in hepatic L8824 cells by regulating energy metabolism and rat sarcoma (RAS)/rapidly accelerated fibrosarcoma (RAF)/mitogen-activated extracellular signal-regulated kinase (MEK)/extracellular regulated protein kinases (ERK) signaling by activating nitric oxide (NO). First, we selected 0, 50, 200, and 500 μg/mL as the challenge doses, according to the inhibitory concentration of 50% (IC50) of glyphosate. The results showed that glyphosate exposure increased the enzyme activity of inducible nitric oxide synthase (iNOS), which in turn increased the NO content. The activity and expression of enzymes related to energy metabolism, such as hexokinase (HK)1, HK2, phosphofructokinase (PFK), phosphokinase (PK), succinate dehydrogenase (SDH), and nicotinamide adenine dinucleotide with hydrogen (NADH), were inhibited, and the RAS/RAF/MEK/ERK signaling pathway was activated. This led to the negative expression of mammalian target of rapamycin (mTOR) and P62 in hepatic L8824 cells and the activation of the autophagy marker genes microtubule-associated proteins light chain 3 (LC3) and Beclin1 to induce autophagy. The above results were dependent on glyphosate concentration. To verify whether autophagy can be excited by the RAS/RAF/MEK/ERK signaling pathway, we treated L8824 cells with the ERK inhibitor U0126 and found that the autophagy gene LC3 was reduced due to the inhibition of ERK, thus demonstrating the reliability of the results. In conclusion, our results demonstrate that glyphosate can induce autophagy in hepatic L8824 cells by activating NO, thus regulating energy metabolism and the RAS/RAF/MEK/ERK signaling pathway.