Efficacy of Rhamnus utilis Decne. Aqueous extract in mice with acute alcoholic liver injury and metabolomic study.

Rhamnus utilis Decne. (Family Rhamnaceae Juss.) leaf is commonly prepared as a anti-inflammatory herbal medicine and used for tea production. To investigate the mechanism of Rhamnus utilis Decne. aqueous extract (RDAE) against acute alcoholic liver disease (ALD) in mice. The ALD mouse (Male ICR) model was induced via intragastric administration of 52 % alcohol. Mice in each group were treated by gavage once daily with the RDAE (1.12, 2.25, 4.500 g/kg). The expression of proteins involved in the MAPKs/NF-κB/COX-2-iNOS pathway was measured by western blotting. Non-targeted metabolomics was used to determine metabolic profiles and critical pathways, while targeted metabolomics validated key amino acid metabolites. After administration of RDAE, the body mass of mice was significantly increased. The liver index was significantly decreased. Meanwhile, the serum levels of AST, ALT, TG, TC, MDA, TNF-α, IL-1ß and IL-6 were significantly decreased (P < 0.05, P < 0.01), but GSH level was inversely increased (P < 0.05). Metabolomic analysis revealed nine major pathways involved in the therapeutic effect of RDAE, including fructose and mannose metabolism. The levels of 7 amino acids including leucine, proline and alanine/sarcosine were significantly upregulated. Additionally, protein levels of p-NF-κB (p65)/NF-κB (p65), p-ERK1/2/ERK1/2, p-JNK/JNK, p-p38/p38, COX-2 and iNOS were significantly decreased (P < 0.01, P < 0.05). RDAE is used to treat acute ALD by improving lipid metabolism, inhibiting the expression of pro-inflammatory cytokines and regulating MAPKs/NF-κB/COX-2-iNOS signalling pathway. These findings provide valuable insights for acute ALD therapy based on traditional Chinese medicine (TCM).

Feasibility exploration of GSH in the treatment of acute hepatic encephalopathy from the aspects of pharmacokinetics, pharmacodynamics, and mechanism.

Our previous study highlighted the therapeutic potential of glutathione (GSH), an intracellular thiol tripeptide ubiquitous in mammalian tissues, in mitigating hepatic and cerebral damage. Building on this premise, we posited the hypothesis that GSH could be a promising candidate for treating acute hepatic encephalopathy (AHE). To verify this conjecture, we systematically investigated the feasibility of GSH as a therapeutic agent for AHE through comprehensive pharmacokinetic, pharmacodynamic, and mechanistic studies using a thioacetamide-induced AHE rat model. Our pharmacodynamic data demonstrated that oral GSH could significantly improve behavioral scores and reduce hepatic damage of AHE rats by regulating intrahepatic ALT, AST, inflammatory factors, and homeostasis of amino acids. Additionally, oral GSH demonstrated neuroprotective effects by alleviating the accumulation of intracerebral glutamine, down-regulating glutamine synthetase, and reducing taurine exposure. Pharmacokinetic studies suggested that AHE modeling led to significant decrease in hepatic and cerebral exposure of GSH and cysteine. However, oral GSH greatly enhanced the intrahepatic and intracortical GSH and CYS in AHE rats. Given the pivotal roles of CYS and GSH in maintaining redox homeostasis, we investigated the interplay between oxidative stress and pathogenesis/treatment of AHE. Our data revealed that GSH administration significantly relieved oxidative stress levels caused by AHE modeling via down-regulating the expression of NADPH oxidase 4 (NOX4) and NF-κB P65. Importantly, our findings further suggested that GSH administration significantly regulated the excessive endoplasmic reticulum (ER) stress caused by AHE modeling through the iNOS/ATF4/Ddit3 pathway. In summary, our study uncovered that exogenous GSH could stabilize intracerebral GSH and CYS levels to act on brain oxidative and ER stress, which have great significance for revealing the therapeutic effect of GSH on AHE and promoting its further development and clinical application.

Anti-Inflammatory Activities of (+)-Afzelechin against Lipopolysaccharide-Induced Inflammation.

In this study, we investigated the potential protective effects of (+)-afzelechin (AZC), a natural compound that is derived from Bergenia ligulata, on lipopolysaccharide (LPS)-induced inflammatory responses. AZC is known to have antioxidant, anticancer, antimicrobial, and cardiovascular protective properties. However, knowledge regarding the therapeutic potential of AZC against LPS-induced inflammatory responses is limited. Thus, we investigated the protective attributes of AZC against inflammatory damage caused by LPS exposure. We examined the effects of AZC on heme oxygenase (HO)-1, cyclooxygenase (COX)-2, and inducible nitric oxide synthase (iNOS) in LPS-activated human umbilical vein endothelial cells (HUVECs). In addition, the effects of AZC on the expression of iNOS, tumor necrosis factor (TNF)-α, and interleukin (IL)-1ß were analyzed in the lung tissues of LPS-injected mice. Data revealed that AZC promoted the production of HO-1, inhibited the interaction between luciferase and nuclear factor (NF)-κB, and reduced the levels of COX-2/PGE2 and iNOS/NO, thereby leading to a decrease in the signal transducer and activator of transcription (STAT)-1 phosphorylation. Moreover, AZC facilitated the nuclear translocation of Nrf2, increased the binding activity between Nrf2 and the antioxidant response elements (AREs), and lowered the expression of IL-1ß in the LPS-treated HUVECs. In the animal model, AZC significantly reduced the expression of iNOS in the lung tissue structure and the TNF-α level in the bronchoalveolar lavage fluid. These findings demonstrate that AZC possesses anti-inflammatory properties that regulate iNOS through the inhibition of both NF-κB expression and p-STAT-1. Consequently, AZC has potential as a future candidate for the development of new clinical substances for the treatment of pathological inflammation.

Immunomodulation by glucocorticoid-induced leucine zipper in macrophages: enhanced phagocytosis, protection from pyroptosis, and altered mitochondrial function.

Glucocorticoids, which have long served as fundamental therapeutics for diverse inflammatory conditions, are still widely used, despite associated side effects limiting their long-term use. Among their key mediators is glucocorticoid-induced leucine zipper (GILZ), recognized for its anti-inflammatory and immunosuppressive properties. Here, we explore the immunomodulatory effects of GILZ in macrophages through transcriptomic analysis and functional assays. Bulk RNA sequencing of GILZ knockout and GILZ-overexpressing macrophages revealed significant alterations in gene expression profiles, particularly impacting pathways associated with the inflammatory response, phagocytosis, cell death, mitochondrial function, and extracellular structure organization activity. GILZ-overexpression enhances phagocytic and antibacterial activity against Salmonella typhimurium and Escherichia coli, potentially mediated by increased nitric oxide production. In addition, GILZ protects macrophages from pyroptotic cell death, as indicated by a reduced production of reactive oxygen species (ROS) in GILZ transgenic macrophages. In contrast, GILZ KO macrophages produced more ROS, suggesting a regulatory role of GILZ in ROS-dependent pathways. Additionally, GILZ overexpression leads to decreased mitochondrial respiration and heightened matrix metalloproteinase activity, suggesting its involvement in tissue remodeling processes. These findings underscore the multifaceted role of GILZ in modulating macrophage functions and its potential as a therapeutic target for inflammatory disorders, offering insights into the development of novel therapeutic strategies aimed at optimizing the benefits of glucocorticoid therapy while minimizing adverse effects.

Liver Histopathological and Immunohistochemical Evaluation from Fasciola hepatica Experimentally Infected and Reinfected Sheep.

Fasciolosis is an important economic disease of livestock. There is a global interest in the development of protective vaccines since the current anthelmintic therapy is no longer sustainable. A better knowledge of the host-parasite interaction is needed to design effective vaccines. To date, few studies have evaluated host-parasite interaction by comparing infected and reinfected animals. The present study evaluates the microscopical hepatic lesions in sheep infected and reinfected with Fasciola hepatica during the acute and chronic stages of infection. The histopathological study revealed the presence of necrotizing foci (NF1) associated with larvae migration during the early stages of infection in the primoinfected (PI) and reinfected (RI) groups. In the late stages of infection of the PI group and at the early and late stages of infection in the RI groups, extensive necrotizing/hemorrhagic foci (NF2) were found in the vicinity of enlarged bile ducts, some containing adult flukes, suggesting parasites may have caused NF2 while feeding. The immunohistochemical study revealed an increase in Foxp3+ T cells in both PI and RI groups with respect to the UC group and in the infiltrates adjacent to NF1 in the RI groups with respect to the PI group, suggesting the F. hepatica induce Foxp3 T cell expansion to facilitate parasite survival. In addition, in both the PI and RI groups, and during acute and chronic stages of the infection, a poor expression of iNOS was found accompanied by a strong expression of CD163, suggesting a marked M2 activation of macrophages in the hepatic lesions, which may be related with healing processes, and it also may facilitate parasite survival. The main differences between PI and RI animals were the more severe infiltration of eosinophils and Foxp3+ T cells, whereas RI did not modify M2 activation of macrophages which occurs since the early stages of primoinfection.

Zwitterion-Lubricated Hydrogel Microspheres Encapsulated with Metformin Ameliorate Age-Associated Osteoarthritis.

Chondrocyte senescence and reduced lubrication play pivotal roles in the pathogenesis of age-related osteoarthritis (OA). In the present study, highly lubricated and drug-loaded hydrogel microspheres are designed and fabricated through the radical polymerization of sulfobetaine (SB)-modified hyaluronic acid methacrylate using microfluidic technology. The copolymer contains a large number of SB and carboxyl groups that can provide a high degree of lubrication through hydration and form electrostatic loading interactions with metformin (Met@SBHA), producing a high drug load for anti-chondrocyte senescence. Mechanical, tribological, and drug release analyses demonstrated enhanced lubricative properties and prolonged drug dissemination of the Met@SBHA microspheres. RNA sequencing (RNA-seq) analysis, network pharmacology, and in vitro assays revealed the extraordinary capacity of Met@SBHA to combat chondrocyte senescence. Additionally, inducible nitric oxide synthase (iNOS) has been identified as a promising protein modulated by Met in senescent chondrocytes, thereby exerting a significant influence on the iNOS/ONOO-/P53 pathway. Notably, the intra-articular administration of Met@SBHA in aged mice ameliorated cartilage senescence and OA pathogenesis. Based on the findings of this study, Met@SBHA emerges as an innovative and promising strategy in tackling age-related OA serving the dual function of enhancing joint lubrication and mitigating cartilage senescence.

17ß-estradiol promotes myeloid-derived suppressor cells functions and alleviates inflammatory bowel disease by activation of Stat3 and NF-κB signalings.

Inflammatory bowel disease (IBD) describes a group of clinically common autoimmune diseases characterized by chronic intestinal inflammation, with gender differences in prevalence. Estrogen has been previously shown to exert anti-inflammatory action in IBD development, however, the mechanisms remain obscure. Recent research has revealed that myeloid-derived suppressor cells (MDSCs) play a protective role in IBD pathogenesis. To investigate the molecular mechanisms of estrogen steroid 17ß-estradiol (E2) in IBD progression, we established IBD mouse models (DNB-induced) with or without prior ovariectomy (OVX) and E2 implantation. We found that OVX led to worse IBD symptoms and reduced MDSCs frequency, whereas E2 significantly alleviated these effects in vivo. Moreover, in vitro experiments showed that E2 promoted the proliferation and immunosuppressive function of MDSCs through phosphorylation of Stat3 and p65. Mechanistically, E2-mediated Stat3/p65 phosphorylation depends on the interaction between HOTAIR, a long non-coding RNA that are well-known in MDSCs proliferation, and Stat3/p65 respectively. In conclusion, our study revealed that E2 promotes the expansion and immunosuppressive function of MDSCs, and thus diminished the occurrence and development of IBD.

To kill a tachyzoite: assault and battery.

Polymeric guanylate-binding proteins (GBPs) physically dismember the vacuole membrane formed by Toxoplasma gondii while nitric oxide (NO) poisons and inhibits parasite replication within interferon (IFN)-γ activated macrophages. Zhao et al. report a novel mechanism for synergy between these classical microbicidal and microbistatic effectors in cell-autonomous immunity to the intracellular parasites.

Mesenchymal stem cells improve cardiac function in diabetic rats by reducing cardiac injury biomarkers and downregulating JAK/STAT/iNOS and iNOS/Apoptosis signaling pathways.

Cardiovascular complications are prevalent manifestations of type 2 diabetes mellitus (T2DM) and are usually the main cause of death. This study aims to show the underlying mechanisms of the potential therapeutic effect of mesenchymal stem cells (MSCs) on diabetic cardiac dysfunction. Twenty-four male Wistar rats were randomly assigned to one of three groups The control group received standard laboratory chow, and the groups with T2DM received a single dose of 45 mg/kg body weight of streptozotocin (STZ) after 3 weeks of pretreatment with a high-fat diet (HFD). Eight weeks after the diagnosis of T2DM, rats were divided into two groups: the T2DM model group and the T2DM + MSCs group. BM-MSCs were administered systemically at 2 × 106 cells/rat doses. A Significant amelioration in Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and dyslipidemia was noted 2 weeks post-administration of MSCs. Administration of MSCs improved dyslipidemia, the altered cardiac injury biomarkers (p ≤ 0.0001), downregulated Janus kinase 2/signal transducer and activator of transcription 3(JAK2/STAT3)/inducible Nitric oxide synthase (iNOS) and iNOS/Apoptosis signaling pathways. This was associated with improved cardiac dysfunction (impaired left ventricular performance and decreased contractility index). Our results show that MSCs ameliorate cardiac dysfunction associated with diabetic cardiomyopathy by lowering dyslipidemia and insulin resistance, inhibiting oxidative stress, and inflammation, downregulating JAK2/STAT3/iNOS and iNOS/Apoptosis signaling pathways.

Synthesis and anti-inflammatory activity of mogrol derivatives modified at C24 site.

Mogrol, the aglycone of well-known sweeter mogrosides, shows potent anti-inflammatory activity. In this study, forty-two mogrol derivatives bearing various pharmacophores with oxygen or nitrogen atoms were designed and synthesized via structural modification at C24 site, and their anti-inflammatory activity were screened against lipopolysaccharide (LPS)-induced RAW264.7 cells. Compared with mogrol, most of derivatives exhibited stronger inhibition of NO production without cytotoxicity. In particular, compound B5 that contained an indole motif effectively suppressed the secretion of inflammatory mediators including TNF-α and IL-6, and inhibited the expression levels of TLR4, p-p65 and iNOS proteins. Molecular docking showed that the active B5 interacted with amino acid residues of iNOS protein through π-π stacking and hydrophobic interactions with binding affinity value of -12.1 kcal/mol, which was much stronger than mogrol (-8.9 kcal/mol). These results suggest that derivative B5 is a promising anti-inflammatory molecule and the strategy of hybridizing indole skeleton on mogrol is worthy for further attention.

Modulating Nitric Oxide: Implications for Cytotoxicity and Cytoprotection.

Despite the significant progress in the fields of biology, physiology, molecular medicine, and pharmacology; the designation of the properties of nitrogen monoxide in the regulation of life-supporting functions of the organism; and numerous works devoted to this molecule, there are still many open questions in this field. It is widely accepted that nitric oxide (•NO) is a unique molecule that, despite its extremely simple structure, has a wide range of functions in the body, including the cardiovascular system, the central nervous system (CNS), reproduction, the endocrine system, respiration, digestion, etc. Here, we systematize the properties of •NO, contributing in conditions of physiological norms, as well as in various pathological processes, to the mechanisms of cytoprotection and cytodestruction. Current experimental and clinical studies are contradictory in describing the role of •NO in the pathogenesis of many diseases of the cardiovascular system and CNS. We describe the mechanisms of cytoprotective action of •NO associated with the regulation of the expression of antiapoptotic and chaperone proteins and the regulation of mitochondrial function. The most prominent mechanisms of cytodestruction-the initiation of nitrosative and oxidative stresses, the production of reactive oxygen and nitrogen species, and participation in apoptosis and mitosis. The role of •NO in the formation of endothelial and mitochondrial dysfunction is also considered. Moreover, we focus on the various ways of pharmacological modulation in the nitroxidergic system that allow for a decrease in the cytodestructive mechanisms of •NO and increase cytoprotective ones.

Blends of Organic Acids Are Weaponizing the Host iNOS and Nitric Oxide to Reduce Infection of Piscirickettsia salmonis in vitro.

For the last 30 years, Piscirickettsia salmonis has caused major economic losses to the aquaculture industry as the aetiological agent for the piscirickettsiosis disease. Replacing the current interventions, based on antibiotics, with natural alternatives (e.g., organic acids) represents a priority. With this study, we aimed to better understand their biological mechanism of action in an in vitro model of infection with salmon epithelial cells (CHSE-214). Our first observation revealed that at the sub-inhibitory concentration of 0.5%, the organic acid blend (Aq) protected epithelial cell integrity and significantly reduced P. salmonis invasion. The MIC was established at 1% Aq and the MBC at 2% against P. salmonis. The sub-inhibitory concentration significantly increased the expression of the antimicrobial peptides Cath2 and Hepcidin1, and stimulated the activity of the innate immune effector iNOS. The increase in iNOS activity also led to higher levels of nitric oxide (NO) being released in the extracellular space. The exposure of P. salmonis to the endogenous NO caused an increase in bacterial lipid peroxidation levels, a damaging effect which can ultimately reduce the pathogen's ability to attach or multiply intracellularly. We also demonstrate that the increased NO release by the host CHSE-214 cells is a consequence of direct exposure to Aq and is not dependent on P. salmonis infection. Additionally, the presence of Aq during P. salmonis infection of CHSE-214 cells significantly mitigated the expression of the pro-inflammatory cytokines IL-1ß, IL-8, IL-12, and IFNγ. Taken together, these results indicate that, unlike antibiotics, natural antimicrobials can weaponize the iNOS pathway and secreted nitric oxide to reduce infection and inflammation in a Piscirickettsia salmonis in vitro model of infection.

Corrigendum: In silico and in vivo evaluation of the anti-cryptosporidial activity of eugenol.

[This corrects the article DOI: 10.3389/fvets.2024.1374116.].

Development of novel nitric oxide production inhibitors based on the 7H-pyrrolo[2,3-d]pyrimidine scaffold.

Nitric oxide (NO), the smallest signaling molecule known, can be excessively produced by overexpressed inducible nitric oxide synthase (iNOS), and eventually leads to multiple inflammatory related diseases. Thus, reducing the overexpression of NO represents as very potential anti-inflammatory strategy. In current study, a series of compounds were designed and synthesized based on the hybridization of 7H-pyrrolo[2,3-d]pyrimidine and cinnamamide fragments in order to develop novel NO production inhibitors. Among them, compound S2h displayed a vigorous inhibitory activity on NO production with an IC50 value of 3.21 ± 0.67 µM, which was much lower than that of the positive control Nω-nitro-L-arginine (L-NNA, IC50 = 28.36 ± 3.13 µM). Due to its obeying Lipinski's and Veber's rules that guarantee compounds with good oral bioavailability, S2h effectively suppressed the paw swelling in carrageenan-induced mice. Additionally, compound S2h formed clear interactions with iNOS protein according to the docking analysis. Therefore, compounds S2h is a promising lead compound for further development of potent iNOS inhibitors or anti-inflammatory agents.

A Role for iNOS in Erastin Mediated Reduction of P-Glycoprotein Transport Activity.

The blood-brain barrier is composed of both a physical barrier and an enzymatic barrier. Tight junction (TJ) proteins expressed between endothelial cells of brain capillaries provide the physical barrier to paracellular movement of ions and molecules to the brain, while luminal-facing efflux transporters enzymatically restrict the entry of blood-borne molecules from entering the brain. The expression and activity of ATP Binding Cassette transporters or "ABC" transporters in endothelial cells of the BBB and in human tumor cells are dynamically regulated by numerous signaling pathways. P-glycoprotein (P-gp), (ABCB1), is arguably the most studied transporter of the BBB, and in human cell lines. P-glycoprotein transport activity is rapidly inhibited by signaling pathways that call for the rapid production of nitric oxide (NO) from the inducible nitric oxide synthase enzyme, iNOS. This study investigated how nano-molar levels of the selective chemotherapeutic erastin affect the activity or expression of P-glycoprotein transporter in brain capillaries and in human tumor cell lines. We chose erastin because it signals to iNOS for NO production at low concentrations. Furthermore, erastin inhibits the cellular uptake of cystine through the XC- cystine/glutamate antiporter. Since previous reports indicate that NO production from iNOS can rapidly inhibit P-gp activity in tumor cells, we wondered if induction of iNOS by erastin could also rapidly reduce P-glycoprotein transport activity in brain endothelial cells and in human tumor cell lines. We show here that low concentrations of erastin (1 nM) can induce iNOS, inhibit the activity of P-glycoprotein, and reduce the intracellular uptake of cystine via the Xc- cystine/glutamate antiporter. Consistent with reduced P-glycoprotein activity in rat brain capillary endothelial cells, we show that human tumor cell lines exposed to erastin become more sensitive to cytotoxic substrates of P-glycoprotein.

Cannabidiol prevents LPS-induced inflammation by inhibiting the NLRP3 inflammasome and iNOS activity in BV2 microglia cells via CB2 receptors and PPARγ.

Neuroinflammation stands as a critical player in the pathogenesis of diverse neurological disorders, with microglial cells playing a central role in orchestrating the inflammatory landscape within the central nervous system. Cannabidiol (CBD) has gained attention for its potential to elicit anti-inflammatory responses in microglia, offering promising perspectives for conditions associated with neuroinflammation. Here we investigated whether the NLRP3 inflammasome and inducible nitric oxide synthase (iNOS) are involved in the protective effects of CBD, and if their modulation is dependent on cannabinoid receptor 2 (CB2) and PPARγ signalling pathways. We found that treatment with CBD attenuated pro-inflammatory markers in lipopolysaccharide (LPS)-challenged BV2 microglia in a CB2- and PPARγ-dependent manner. At a molecular level, CBD inhibited the LPS-induced pro-inflammatory responses by suppressing iNOS and NLRP3/Caspase-1-dependent signalling cascades, resulting in reduced nitric oxide (NO), interleukin-1ß (IL-1ß), and tumour necrosis factor-alpha (TNF-α) concentrations. Notably, the protective effects of CBD on NLRP3 expression, Caspase-1 activity, and IL-1ß concentration were partially hindered by the antagonism of both CB2 receptors and PPARγ, while iNOS expression and NO secretion were dependent exclusively on PPARγ activation, with no CB2 involvement. Interestingly, CBD exhibited a protective effect against TNF-α increase, regardless of CB2 or PPARγ activation. Altogether, these findings indicate that CB2 receptors and PPARγ mediate the anti-inflammatory effects of CBD on the NLRP3 inflammasome complex, iNOS activity and, ultimately, on microglial phenotype. Our results highlight the specific components responsible for the potential therapeutic applications of CBD on neuroinflammatory conditions.

Proinflammatory microglial response is a common mechanism of Aroclor 1254- and Tetrabromobisphenol-A-induced neurotoxicity in immature chronically exposed rats.

Polychlorinated biphenyls (PCBs) and brominated flame retardants (BFRs) are dominant environmental and food contaminants. Tetrabromobisphenol A (TBBPA) is the most widely used BFR in the world to improve the fire safety of laminates in electrical and electronic equipment. Aroclor 1254, one of the PCBs, is widely distributed in the environment due to its extensive use in industrial applications around the world. Both groups of substances are potent toxicants. There is also increasing evidence that they have neurotoxic effects. In this study we tested the pro-inflammatory effects of Aroclor 1254 and TBBPA based on markers of microglial reactivity and levels of pro-inflammatory factors in the brain of immature rats. Aroclor 1254 or TBBPA were administered to the rats by oral gavage for two weeks at a dose of 10 mg/kg b.w. Both light and electron microscopy studies revealed features indicative of microglia activation in brains of exposed rats. Morphological changes were associated with overexpression of pro-inflammatory enzymes such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Analysis of cytokine/chemokine array revealed significant secretion of inflammatory mediators following exposure to both TBBPA and Aroclor 1254, which was stronger in the cerebellum than in the forebrain of exposed immature rats. The results indicate a pro-inflammatory profile of microglia activation as one of the neurotoxic mechanisms of both examined toxicants.

Neuroimmunomodulatory effect of Nitric Oxide on chronic wound healing after photodynamic therapy.

Neuroimmunomodulation is the capacity of the nervous system to regulate immune processes. The existence of neurotransmitter receptors in immune cells enables this phenomenon to take place. Neuronal mediators possess the capacity to direct and control several occurrences during the wound healing process. Nitric oxide (NO) functions as a neuromodulator, playing a crucial role in the regulation of vascular tone and blood pressure with antimicrobial properties. Photodynamic therapy has been shown to augment the function of immune cells involved in the healing process of venous leg ulcers. Nitric oxide can be secreted into the extracellular environment by these cells. In lesions treated with PDT, the synthesis of iNOs (the enzyme that releases NO) increased, as demonstrated by the experimental results. Therefore the significance of PDT in enhancing the clinical condition of the lesion is thus highlighted.

iNOS regulates hematopoietic stem and progenitor cells via mitochondrial signaling and is critical for bone marrow regeneration.

Hematopoietic stem cells (HSCs) replenish blood cells under steady state and on demand, that exhibit therapeutic potential for Bone marrow failures and leukemia. Redox signaling plays key role in immune cells and hematopoiesis. However, the role of reactive nitrogen species in hematopoiesis remains unclear and requires further investigation. We investigated the significance of inducible nitric oxide synthase/nitric oxide (iNOS/NO) signaling in hematopoietic stem and progenitor cells (HSPCs) and hematopoiesis under steady-state and stress conditions. HSCs contain low levels of NO and iNOS under normal conditions, but these increase upon bone marrow stress. iNOS-deficient mice showed subtle changes in peripheral blood cells but significant alterations in HSPCs, including increased HSCs and multipotent progenitors. Surprisingly, iNOS-deficient mice displayed heightened susceptibility and delayed recovery of blood progeny following 5-Fluorouracil (5-FU) induced hematopoietic stress. Loss of quiescence and increased mitochondrial stress, indicated by elevated MitoSOX and MMPhi HSCs, were observed in iNOS-deficient mice. Furthermore, pharmacological approaches to mitigate mitochondrial stress rescued 5-FU-induced HSC death. Conversely, iNOS-NO signaling was required for demand-driven mitochondrial activity and proliferation during hematopoietic recovery, as iNOS-deficient mice and NO signaling inhibitors exhibit reduced mitochondrial activity. In conclusion, our study challenges the conventional view of iNOS-derived NO as a cytotoxic molecule and highlights its intriguing role in HSPCs. Together, our findings provide insights into the crucial role of the iNOS-NO-mitochondrial axis in regulating HSPCs and hematopoiesis.