Arginase Activity Research Articles

Garcinia cowa bark extract induces oxidative stress mediated cellular apoptosis in Leishmania donovani parasite modulated by its active phytosterol constituent

Visceral leishmaniasis still remains a leading cause of parasitic deaths, with modern pentavalent antimonials showing limited efficacy and health risks. The methanolic bark extract of the Northeastern Indian plant, Garcinia cowa, demonstrated potent leishmanicidal effects against the parasite Leishmania donovani, demonstrating IC50 values of 20–36 µg/ml, with selective toxicity for parasites over healthy cells. It induced parasite death through elevated oxidative and nitrosative stress elements, reduced arginase activity, nuclear fragmentation, cell cycle arrest, and apoptosis. A GC-MS study and molecular docking identified stigmasterol as a primary component, an antileishmanial compound that inhibits Leishmania donovani parasite efficiently.

Abstract 4138661: Targeting Arginase I Alleviates Cardiomyopathy

Introduction: Emerging data have shown that pathological cardiac fibrosis and heart failure is driven by recruitment of CD4 + T cells to injured heart tissue. Systemic deletion of CD4 + T cells or splenectomy has been shown to attenuate CD4 + T cell heart infiltration and inflammation. We engineered cargo-less nanoparticles using a biocompatible and biodegradable polymer that target splenic macrophages to overexpress arginase I, leading to local depletion of L-arginine, an amino acid crucial for CD4 + T cell activation and expansion. Hypothesis: Cargo-less nanoparticles attenuate CD4 + T cell activation, expansion, and heart infiltration in experimental models of cardiomyopathy by regulating cross talk between macrophages and CD4 + T cells via L-arginine depletion in the spleen. Methods: Spleen-targeting, cargo-less nanoparticles were synthesized from poly(L-lactide-co-glycolide) (PLLGA) and administered to murine and human macrophages in vitro. Arginase I expression and activity were assessed via Western blotting and arginase activity assay. Epigenetic modulation was analyzed using Western blotting and CHIP-seq. Conditioned media was collected to culture CFSE-labeled T cells to assess proliferation. The nanoparticles were administered to mouse heart failure models induced by isoproterenol or angiotensin II and phenylephrine. Immune cell composition in mouse spleens and hearts was investigated by flow cytometry. Cardiac function was assessed by echocardiography and heart fibrosis was examined via immunohistochemistry and Western blotting. Results: Primary murine macrophages treated with our nanoparticles exhibited a dose-dependent T cell suppression in vitro. This effect was abrogated when an arginase inhibitor was administered together with the nanoparticles. The nanoparticles upregulated arginase I protein expression and arginase activity by increasing histone lactylation. In vivo testing with mouse heart injury models showed that the nanoparticles restored levels of effector and regulatory T cells in injured mice to non-injured levels. Additionally, the nanoparticles reduced cardiac fibrosis and restored ejection fraction. Furthermore, Western blotting of heart tissue lysate revealed that the nanoparticles downregulated the TGFb and p-SMAD signaling pathway. Conclusion: Collectively, these findings highlight a novel therapeutic strategy for heart failure, addressing the gap of fibrosis treatment by targeting upstream immunological pathways.

ROLE OF NF-κB ACTIVATION IN CHANGES OF NITRIC OXIDE PRODUCTION IN SKELETAL MUSCLES DURING METABOLIC SYNDROME

Nitric oxide, as a signaling molecule, plays an ambiguous role in many pathological processes. On the one hand, nitric oxide is necessary for maintaining the tone of the vascular wall of arteries and prevents the development of ischemia in various organs and skeletal muscles in particular. On the other hand, excessive production of nitric oxide in the tissue can contribute to the formation of toxic metabolites, such as peroxynitrite that leads to the development of nitrosative damage to various organs and tissues. Metabolic syndrome is also one of the diseases accompanied by disturbances in the nitric oxide production system. Currently, the sources of nitric oxide production, the predominant ways of its metabolism, and the influence of the transcription factor NF-κB on these processes in skeletal muscles under the conditions of the metabolic syndrome are insufficiently studied. The purpose of this study is to study the effect of an inhibitor of the activation of the transcription factor NF-κB on the production of nitric oxide and the concentration of its metabolites in the biceps femoris muscle of rats under the conditions of modeling the metabolic syndrome. The experimental study was carried out on male Wistar rats weighing 200-260 g. The animals were randomly divided into 4 groups of 6 animals each. Animals of group 1 (control group) received a standard vivarium diet. In group 2 (metabolic syndrome), in addition to the standard diet, the animals received a 20% fructose solution as their sole source of drinking water for 60 days. In group 3, the animals were given a standard vivarium diet and were injected intraperitoneally with ammonium pyrrolidine dithiocarbamate at a dose of 76 mg/kg, three times a week for 60 days. Group 4 received the same diet as group 2 along with the injections administered in group 3. In 10% homogenate of the biceps femoris muscle, the following were determined: total NO-synthase activity, activity of constitutive and inducible isoforms of NO-synthase, arginase activity, aitrate- and nitrite reductase activity, concentrations of nitrite, peroxynitrite, nitrosothiols, and sulfides. The administration of ammonium pyrrolidinedithiocarbamate during metabolic syndrome simulation resulted in a reduction in total NO-synthase activity and inducible NO-synthase activity by 33.85% and 34.66%, respectively, compared to the metabolic syndrome group; arginase activity decreased by 37.56%, while nitrate and nitrite reductase activities were reduced by 19.29% and 47.71%, respectively; nitrite concentration increased by 21.77%, peroxynitrite concentration decreased by 32.05%, nitrosothiol concentration increased by 29.27%, and sulfide concentration decreased by 17.39% compared to the group with metabolic syndrome. Activation of the transcription factor NF-κB under metabolic syndrome conditions leads to increased nitric oxide production through both L-arginine-dependent and L-arginine-independent pathways in the biceps femoris muscle, enhances arginase activity, and results in elevated peroxynitrite formation.

Nitrogen deposition and heathland management cause multi‐element stoichiometric mismatches, reducing insect fitness

Abstract Increased nitrogen and acidifying deposition negatively affect biogeochemical cycles and nutrient stoichiometry, particularly in oligotrophic habitats. In heathlands, management aims to mitigate effects of deposition by topsoil removal (sod‐cutting) or by liming to increase soil pH. However, these management efforts may further exacerbate macro‐ and micronutrient stoichiometric mismatch, with cascading effects on heathland insects. Here, we investigate the physiological mechanisms by which deposition and management affect insects, focusing on nutrient uptake and excretion. We combined a phosphorus (P) addition and liming experiment in previously sod‐cut heathland with laboratory‐rearing experiments using the field cricket (Gryllus campestris L., 1) as a model species. We hypothesized that P addition would benefit cricket performance by reducing food N:P ratio. Conversely, we hypothesized that liming would reduce performance by decreasing food Mn:Mg and/or Fe:Mg ratios. Elemental uptake efficiency, consumption and reproduction, as well as cricket field density, were significantly higher under increased P availability, confirming insect P limitation in the field. Liming decreased food Mn:Mg ratio and reduced reproductive success, eliminating any beneficial effects of P addition. Moreover, cricket stoichiometry better explained growth rates than the amount of food consumed. The best model highlighted cricket N and Mn content, with increasing N content negatively influencing growth, while the opposite was true for Mn. We found no support for liming‐induced Fe limitation. We propose that both P and Mn limit crickets independently. Specifically, P limitation affects growth via reduced ribosomal content, and Mn limitation impacts growth by limiting arginase activity and hence restricting the recycling of amino acids. Our study shows that restoration management can fail to restore habitat quality for insects and may even amplify mismatches in macro and micronutrient stoichiometry. To address this, the addition of not only P but also Mn may be required as follow‐up management, but reducing N‐emission remains imperative as this removes the need for disruptive management interventions. Read the free Plain Language Summary for this article on the Journal blog.

Viscoelastic Hydrogel Modulates Phenotype of Macrophage-Derived Multinucleated Cells and Macrophage Differentiation in Foreign Body Reactions.

Biomaterial-induced macrophage-derived multinucleated cells (MNCs) are often observed at or near material implantation sites, yet their subtypes and roles in tissue repair and wound healing remain unclear. This study compares material-induced MNCs to cytokine-induced MNCs using both in vitro and in vivo models. 3D-embedded Raw264.7 cells and rat bone marrow-derived monocytes (BMDMs), with or without cytokines such as IL-4 and RANKL, were characterized for their MNC morphologies and subtypes via in situ immunocytochemistry and flow cytometry. Macrophage polarization and osteoclastic differentiation were assessed through NO production, arginase activity, and tartrate-resistant acid phosphatase levels. 3D matrix-induced MNCs expressed the same phenotypic heterogeneity as the IL-4 and RANK-treated ones. 3D matrix-induced MNCs displayed the same phenotypic heterogeneity as those treated with IL-4 and RANKL. A high viscoelastic matrix (1006.48 ± 92.29 Pa) induced larger populations of proinflammatory and osteoclast-like MNCs, whereas a low viscoelastic matrix (38.61 ± 7.56 Pa) supported active differentiation and gene expression across pro-, anti-inflammatory, and osteoclast-like macrophages. Matrix viscoelasticity also influenced the effects of IL-4 and RANKL on macrophage-derived MNC polarization. In an in vivo subcutaneous implantation model, medium to high viscoelastic matrices exhibited higher populations of CD86+ and RANK+ MNCs, while low viscoelastic matrices showed higher populations of CD206+ MNCs. These findings suggest that matrix viscoelasticity modulates macrophage differentiation and MNC phenotype, with low viscoelastic matrices potentially favoring anti-inflammatory MNCs and macrophage differentiation suitable for subcutaneous implantation.

The roles of arginases and arginine in immunity.

Arginase activity and arginine metabolism in immune cells have important consequences for health and disease. Their dysregulation is commonly observed in cancer, autoimmune disorders and infectious diseases. Following the initial description of a role for arginase in the dysfunction of T cells mounting an antitumour response, numerous studies have broadened our understanding of the regulation and expression of arginases and their integration with other metabolic pathways. Here, we highlight the differences in arginase compartmentalization and storage between humans and rodents that should be taken into consideration when assessing the effects of arginase activity. We detail the roles of arginases, arginine and its metabolites in immune cells and their effects in the context of cancer, autoimmunity and infectious disease. Finally, we explore potential therapeutic strategies targeting arginases and arginine.

Biochemistry, pharmacology and in vivo function of arginases.

Arginase catalyzes the hydrolysis of L-arginine into L-ornithine and urea. The two existing isoforms Arg1 and Arg2 show different cellular localizations and metabolic functions. Arginase activity is crucial for nitrogen detoxification in the urea cycle, synthesis of polyamines, and control of l-arginine bioavailability and nitric oxide production. Despite significant progress in the understanding of the biochemistry and function of arginases, several open questions remain. Recent studies have revealed that the regulation and function of Arg1 and Arg2 are cell-type-specific, species-specific, and profoundly different in mice and humans. The main differences were found in the distribution and function of Arg1 and Arg2 in immune and erythroid cells. Contrary to what was previously thought, Arg1 activity appears to be only partially related to vascular NO signaling under homeostatic conditions in the vascular wall, but its expression is increased under disease conditions and may be targeted by treatment with arginase inhibitors. Arg2 appears to be mainly a catabolic enzyme involved in the synthesis of L-ornithine, polyamine, and proline but may play a putative role in blood pressure control, at least in mice. The immunosuppressive role of arginase-mediated arginine depletion is a promising target for cancer treatment. This review critically revises and discusses the biochemistry, pharmacology, and in vivo function of arginase, focusing on the insights gained from the analysis of cell-specific Arg1 and Arg2 knockout mice and human studies using arginase inhibitors or pegylated recombinant arginase. Significance Statement The review emphasizes the need for further research to deepen our understanding of the regulation of Arg1 and Arg 2 in different cell types under consideration of their localization, species-specificity, and multiple biochemical and physiological roles. This could lead to better pharmacological strategies to target arginase activity in liver, cardiovascular, hematological, immune/infection diseases and cancer.

Engineered microparticles modulate arginine metabolism to repolarize tumor-associated macrophages for refractory colorectal cancer treatment

BackgroundArginase is abundantly expressed in colorectal cancer and disrupts arginine metabolism, promoting the formation of an immunosuppressive tumor microenvironment. This significant factor contributes to the insensitivity of colorectal cancer to immunotherapy. Tumor-associated macrophages (TAMs) are major immune cells in this environment, and aberrant arginine metabolism in tumor tissues induces TAM polarization toward M2-like macrophages. The natural compound piceatannol 3ʹ-O-glucoside inhibits arginase activity and activates nitric oxide synthase, thereby reducing M2-like macrophages while promoting M1-like macrophage polarization.MethodsThe natural compounds piceatannol 3ʹ-O-glucoside and indocyanine green were encapsulated within microparticles derived from tumor cells, termed PG/ICG@MPs. The enhanced cancer therapeutic effect of PG/ICG@MP was assessed both in vitro and in vivo.ResultsPG/ICG@MP precisely targets the tumor site, with piceatannol 3ʹ-O-glucoside concurrently inhibiting arginase activity and activating nitric oxide synthase. This process promotes increased endogenous nitric oxide production through arginine metabolism. The combined actions of nitric oxide and piceatannol 3ʹ-O-glucoside facilitate the repolarization of tumor-associated macrophages toward the M1 phenotype. Furthermore, the increase in endogenous nitric oxide levels, in conjunction with the photodynamic effect induced by indocyanine green, increases the quantity of reactive oxygen species. This dual effect not only enhances tumor immunity but also exerts remarkable inhibitory effects on tumors.ConclusionOur research results demonstrate the excellent tumor-targeting effect of PG/ICG@MPs. By modulating arginine metabolism to improve the tumor immune microenvironment, we provide an effective approach with clinical translational significance for combined cancer therapy.

C57BL/6 Peritoneal Macrophage Exosomes Improve Antileishmanial Functions of the RAW264.7 Cells.

Leishmaniasis is considered one of the most critical health concerns in the world. Unfortunately, no protective vaccines exist and conventional treatments are relatively ineffective. Therefore, new strategies are necessary against leishmaniasis. In recent years, exosomes have shown promising therapeutic outcomes in various diseases, including infectious diseases. In this regard, we aimed to explore the effect of the exosome, pyrimethamine and their combination on the anti-parasitic function of RAW264.7 cells against Leishmania major. Exosomes were isolated from the C57BL/6 peritoneal macrophages. L. major infected and non-infected RAW264.7 cells treated with exosomes, pyrimethamine (PM), and exosomes along with PM. The effect of the treatments was analysed on phagocytosis, efferocytosis, the intracellular parasite count, arginase activity, nitric oxide (NO) and reactive oxygen species (ROS) production. Exosomes could significantly elevate the phagocytosis, efferocytosis, NO and ROS in both infected and non-infected groups (Pv < 0.05). The exosomes reduced the arginase activity in both groups (Pv < 0.05). The intracellular parasite count was significantly lower after treatment with exosomes (Pv < 0.05). These results demonstrate that MQ-derived exosomes can enhance in vitro anti-parasitic responses against L. major. This provides a potential pathway for more effective treatments and underscores the importance of further research in this area.

356 Exploring the manganese requirement of feedlot steers

Abstract Angus-cross steers [n = 144; body weight (BW) = 359 kg ± 13.4] were used to assess the effect of dietary Mn and steroidal implants on trace mineral (TM) status, and liver and serum metabolites related to N metabolism. Steers (n = 6/pen) were stratified by BW in a 3 × 2 factorial. GrowSafe bunks recorded individual feed intake (experimental unit = steer; n = 24/treatment). Dietary treatments included (MANG; 8 pens per treatment; Mn as MnSO4): 1) no supplemental Mn (analyzed 14 mg Mn/kg DM; Mn0); 2) 20 mg supplemental Mn/kg DM (Mn20); 3) 50 mg supplemental Mn/kg DM (Mn50). Within MANG, steers received a steroidal implant treatment (IMP) on d 0: 1) no implant; NO; or 2) combination implant (Revalor-200; REV). Liver biopsies for TM analysis and qPCR, and blood for serum urea-N (SUN) analysis were collected on d 0, 20, 40, and 77. Liver TM, serum metabolite, enzyme activity, and gene expression data were analyzed as repeated measures using PROC MIXED of SAS 9.4. The Correlation Procedure of SAS 9.4 was utilized to assess correlations between liver arginase activity, SUN concentrations, and liver Mn concentrations. No MANG × IMP effects were noted (P ≥ 0.12) for growth or carcass measures. Steroidal implants increased final BW (FBW), overall average daily gain (ADG), and gain to feed (G:F; P ≤ 0.01). Dietary Mn did not influence FBW, overall ADG, or overall G:F (P ≥ 0.14). Liver Mn concentration increased with supplemental Mn (P = 0.01). An IMP × DAY effect was noted for liver Mn (P = 0.01) where NO and REV were similar on d 0 but NO cattle increased liver Mn from d 0 to 20 while REV liver Mn decreased. Relative expression of liver Mn transporter ZnT10 tended to be least (MANG; P = 0.10) in Mn20 while Mn0 and Mn100 were similar. Relative expression of liver Mn transporter ZIP8 was not influenced by MANG, IMP, or MANG × IMP (P ≥ 0.23). Liver arginase activity was not influenced by MANG, IMP, MANG × DAY, IMP × DAY, or MANG × IMP (P ≥ 0.15) but tended to decrease over time (DAY; P = 0.10). On d 0, 20, and 40, arginase activity was correlated (r ≤ 0.33; P ≤ 0.01) with SUN and liver Mn. Relative expression of MnSOD in the liver was greater in REV (P = 0.03) compared with NO and within a MANG × IMP effect (P = 0.01) REV increased liver MnSOD activity. This study indicates current NASEM Mn recommendations are adequate to meet demands of finishing beef cattle given a steroidal implant. This study also reveals how implants and supplemental Mn influence liver enzyme activity and genes related to arginine metabolism, urea synthesis, antioxidant capacity, and TM homeostasis.

Obesity alters the macrophages' response to Leishmania major in C57BL/6 mice.

Obesity is a global pandemic associated with several comorbidities, such as cardiovascular diseases and type 2 diabetes. It is also a predisposing factor for infectious diseases, increasing mortality rates. Moreover, diet-induced obesity can cause metabolic fluctuations that affect macrophage differentiation in various organs. In this sense, we investigated how bone marrow-derived macrophages and tissue-resident macrophages in the skin, which have been differentiated in a host with metabolic syndrome and with previous inflammatory burden, respond to Leishmania major infection. Our findings suggest that bone marrow-derived macrophages from obese C57BL/6 mice, even when cultivated in vitro with inflammatory stimuli, are more susceptible to L. major. These macrophages produce less tumor necrosing factor (TNF) and nitric oxide (NO) and show higher arginase activity. Furthermore, obese mice infected with an intermediate dose of L. major in the skin had more severe lesions when analyzed for ulceration, diameter, thickness, and parasite burden. The increase in lesion severity in obese mice was associated with a higher frequency of tissue-resident macrophages, which are less efficient in killing parasites. We also used CCR2-/- mice, which predominantly have tissue-resident macrophages, and found that lesion resolution was delayed in association with CCR2 deficiency. Additionally, obesity potentiated tissue damage, resulting in higher frequency of tissue-resident macrophages. Our results demonstrate that obesity can alter macrophage responses to infection, leading to increased susceptibility to L. major and more severe cutaneous leishmaniasis. These findings may have important implications for managing obesity-related infections and the development of new therapies for cutaneous leishmaniasis.

Royal Jelly–Mediated Silver Nanoparticles Show Promising Anticancer Effect on HeLa and A549 Cells Through Modulation of the VEGFa/PI3K/Akt/MMP‐2 Pathway

ABSTRACTIn recent years, nanotechnology has revolutionized various sectors, particularly in nanomedicine, where nanomaterials are used for diagnosis, monitoring, control, prevention, and treatment. Among these, silver nanoparticles (AgNPs) stand out due to their remarkable antimicrobial and cytotoxic properties. Traditional chemical synthesis of AgNPs poses significant environmental and health risks. This study introduces a novel, eco‐friendly synthesis method using royal jelly (RJ), a nutrient‐rich secretion from honeybees, to produce AgNPs with potent anticancer effects. Our research provides a detailed investigation into RJ‐mediated AgNPs’ modulation of the VEGFa/PI3K/Akt/MMP‐2 pathway in HeLa and A549 cancer cell lines. AgNP characterization was performed by applying UV–Vis spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) in combination with selected area electron diffraction (SAED). Cell signaling system components were determined by ELISA analysis. The cells were subjected to staining with hematoxylin and eosin to visualize the treatment’s effects. This study focuses on the green synthesis of AgNPs using RJ and its bioactivity against cancer cells. It provides a detailed characterization of the nanoparticles and examines their effects on cancer cells, specifically HeLa cervical cancer and A549 lung cancer cell lines. Green synthesized AgNPs demonstrate significant cytotoxic effects against HeLa and A549 cancer cell lines. The underlying molecular mechanisms contributing to their anticancer activity were elucidated. Our findings revealed a significant decrease in arginase activity upon exposure to AgNPs, accompanied by reductions in PI3K and phosphorylated and total Akt levels, indicative of pathway inhibition. Additionally, RJAgNP demonstrated a capacity to reduce nitric oxide levels and suppress angiogenesis‐related factors like VEGF and MMP‐2 and inflammation‐related factors like TNF‐α and COX‐2, thus impeding angiogenesis and metastasis. Moreover, our results shed light on the involvement of reactive oxygen intermediates (ROIs) in mediating apoptotic pathways, as evidenced by the increase in malondialdehyde (MDA) concentration and the corresponding decrease in Akt levels, ultimately promoting death in cancer cells. Our study contributes significantly to the field of nanomedicine and cancer therapy by introducing the use of green synthesis AgNPs using RJ and providing in‐depth insights into their molecular mechanisms of anticancer action. Our research findings demonstrate the anticancer potential of RJ‐AgNPs by targeting the VEGFa/PI3K/Akt/MMP‐2 pathway and modulation of ROS/RNS in cancer cells.

Endothelial Cell-Specific Prolyl Hydroxylase-2 Deficiency Augments Angiotensin II-Induced Arterial Stiffness and Cardiac Pericyte Recruitment in Mice.

Endothelial prolyl hydroxylase-2 (PHD2) is essential for pulmonary remodeling and hypertension. In the present study, we investigated the role of endothelial PHD2 in angiotensin II-mediated arterial stiffness, pericyte recruitment, and cardiac fibrosis. Chondroitin sulfate proteoglycan 4 tracing reporter chondroitin sulfate proteoglycan 4- red fluorescent protein (DsRed) transgenic mice were crossed with PHD2flox/flox (PHD2f/f) mice and endothelial-specific knockout of PHD2 (PHD2ECKO) mice. Transgenic PHD2f/f (TgPHD2f/f) mice and TgPHD2ECKO mice were infused with angiotensin II for 4 weeks. Arterial thickness, stiffness, and histological and immunofluorescence of pericytes and fibrosis were measured. Infusion of TgPHD2f/f mice with angiotensin II resulted in a time-dependent increase in pulse-wave velocity. Angiotensin II-induced pulse-wave velocity was further elevated in the TgPHD2ECKO mice. TgPHD2ECKO also reduced coronary flow reserve compared with TgPHD2f/f mice infused with angiotensin II. Mechanistically, knockout of endothelial PHD2 promoted aortic arginase activity and angiotensin II-induced aortic thickness together with increased transforming growth factor-β1 and ICAM-1/VCAM-1 expression in coronary arteries. TgPHD2f/f mice infused with angiotensin II for 4 weeks exhibited a significant increase in cardiac fibrosis and hypertrophy, which was further developed in the TgPHD2ECKO mice. Chondroitin sulfate proteoglycan 4 pericyte was traced by DsRed+ staining and angiotensin II infusion displayed a significant increase of DsRed+ pericytes in the heart, as well as a deficiency of endothelial PHD2, which further promoted angiotensin II-induced pericyte increase. DsRed+ pericytes were costained with fibroblast-specific protein 1 and α-smooth muscle actin for measuring pericyte-myofibroblast cell transition. The knockout of endothelial PHD2 increased the amount of DsRed+/fibroblast-specific protein 1+ and DsRed+/α-smooth muscle actin+ cells induced by angiotensin II infusion. Knockout of endothelial PHD2 enhanced angiotensin II-induced cardiac fibrosis by mechanisms involving increasing arterial stiffness and pericyte-myofibroblast cell transitions.

Differences in endothelial function between patients with Type 1 and Type 2 diabetes: effects of red blood cells and arginase.

The mechanisms underlying endothelial dysfunction in Type 1 and Type 2 diabetes (T1DM and T2DM) are unresolved. The red blood cells (RBCs) with increased arginase activity induce endothelial dysfunction in T2DM, but the implications of RBCs and the role of arginase inhibition in T1DM are unexplored. We aimed to investigate the differences in endothelial function in patients with T1DM and T2DM, with focus on RBCs and arginase. Thirteen patients with T1DM and twenty-six patients with T2DM, matched for HbA1c and sex were included. In vivo endothelium-dependent and -independent vasodilation (EDV and EIDV) were assessed by venous occlusion plethysmography before and after administration of an arginase inhibitor. RBCs were co-incubated with rat aortic segments for 18h followed by evaluation of endothelium-dependent (EDR) and -independent relaxation (EIDR) in isolated organ chambers. In vivo EDV, but not EIDV, was significantly impaired in patients with T2DM compared with patients with T1DM. Arginase inhibition resulted in improved EDV only in T2DM. RBCs from patients with T2DM induced impaired EDR but not EIDR in isolated aortic segments, whereas RBCs from patients with T1DM did not affect EDR nor EIDR. The present study demonstrates markedly impaired EDV in patients with T2DM in comparison with T1DM. In addition, it highlights the divergent roles of RBCs and arginase in mediating endothelial dysfunction in T1DM and T2DM. While endothelial dysfunction is mediated via RBCs and arginase in T2DM, these phenomena are not prominent in T1DM thereby indicating distinct differences in underlying mechanisms.

Nitric Oxide Dysregulation and Vaso-Occlusive Crisis in Sickle Cell Anemia: A Review

Sickle cell anemia (SCA) is a genetic disorder characterized by the production of abnormal hemoglobin S (HbS), leading to chronic hemolysis and recurrent vaso-occlusive crises (VOCs). VOCs are acute, painful episodes caused by the obstruction of blood flow due to sickled red blood cells (RBCs), resulting in tissue ischemia and organ damage. Nitric oxide (NO) plays a crucial role in vascular homeostasis, and its dysregulation is a significant factor in the pathophysiology of SCA, particularly in VOCs. In SCA, chronic hemolysis releases free hemoglobin into the plasma, which scavenges NO and reduces its bioavailability. Additionally, increased arginase activity depletes L-arginine, the substrate for NO synthesis, further diminishing NO production. Oxidative stress exacerbates NO degradation and endothelial dysfunction, amplifying the risk of VOCs. The interplay between NO deficiency, oxidative stress, and endothelial dysfunction creates a vicious cycle that perpetuates vascular damage and increases the frequency and severity of VOCs. This review explores the mechanisms underlying NO dysregulation in SCA and its impact on vascular function. It also discusses potential therapeutic interventions aimed at modulating NO pathways to prevent or reduce VOCs. These interventions include NO donors, L-arginine supplementation, phosphodiesterase inhibitors, antioxidant therapy, and arginase inhibitors. Keywords: Sickle cell anemia, vaso-occlusive crisis, nitric oxide dysregulation, hemolysis, endothelial dysfunction, oxidative stress, therapeutic interventions.

Small Structural Differences in Proline-Rich Decapeptides Have Specific Effects on Oxidative Stress-Induced Neurotoxicity and L-Arginine Generation by Arginosuccinate Synthase.

The proline-rich decapeptide 10c (Bj-PRO-10c; ENWPHPQIPP) from the Bothrops jararaca snake modulates argininosuccinate synthetase (AsS) activity to stimulate L-arginine metabolite production and neuroprotection in the SH-SY5Y cell line. The relationships between structure, interactions with AsS, and neuroprotection are little known. We evaluated the neuroprotective effects of Bj-PRO-10c and three other PROs (Bn-PRO-10a, <ENWPRPKIPP; Bn-PRO-10a-MK, <ENWPRPKIPPMK; and, Bn-PRO-10c, <ENWPRPKVPP) identified from Bitis nasicornis snake venom, with a high degree of similarity to Bj-PRO-10c, on oxidative stress-induced toxicity in neuronal PC12 cells and L-arginine metabolite generation via AsS activity regulation. Cell integrity, metabolic activity, reactive oxygen species (ROS) production, and arginase activity were examined after 4 h of PRO pre-treatment and 20 h of H2O2-induced damage. Only Bn-PRO-10a-MK and Bn-PRO-10c restored cell integrity and arginase function under oxidative stress settings, but they did not reduce ROS or cell metabolism. The MK dipeptide in Bn-PRO-10a-MK and valine (V8) in Bn-PRO-10c are important to these effects when compared to Bn-PRO-10a. Bj-PRO-10c is not neuroprotective in PC12 cells, perhaps because of their limited NMDA-type glutamate receptor activity. The PROs interaction analysis on AsS activation can be rated as follows: Bj-PRO-10c > Bn-PRO-10c > Bn-PRO-10a-MK > Bn-PRO-10a. The structure of PROs and their correlations with enzyme activity revealed that histidine (H5) and glutamine (Q7) in Bj-PRO-10c potentiated their affinity for AsS. Our investigation provides the first insights into the structure and molecular interactions of PROs with AsS, which could possibly further their neuropharmacological applications.

Effects of n-hexane fraction of Piper guineense seed extracton Nω-nitro-L-arginine methyl ester hydrochloride-induced hypertension in rats.

This study aimed to investigate the effects of the n-hexane fraction of the ethanolic seed extract of PG (NFESEPG)on hypertension induced by Nω-nitro-L-argininemethyl ester (L-NAME)in rats. Specifically, the study examined the impact of NFESEPG on blood pressure, oxidative stress markers, NO concentration, angiotensin-converting enzyme (ACE) and arginase activities, and cardiac biomarkers in hypertensive rats. The study involved collecting, identifying, and processing the PG plant to obtain the ethanolic seed extract. The extract was then partitioned with solvents to isolate the n-hexane fraction. Hypertension was induced in rats by oral administration of L-NAMEfor 10 days, while concurrent treatment with NFESEPG at two doses (200 and 400 mg/kg/day) was administered orally. Blood pressure was measured using a noninvasive tail-cuff method, and various biochemical parameters were assessed. Treatment with both doses of NFESEPG significantly reduced systolic and diastolic blood pressure in L-NAME-inducedhypertensive rats. Additionally, NFESEPG administration increased NO concentration and decreased ACE and arginase activities, malondialdehyde (MDA) levels, and cardiac biomarkers in hypertensive rats. The findings indicate that NFESEPG effectively lowered blood pressure in hypertensive rats induced by L-NAME,potentially through mechanisms involving the modulation of oxidative stress, NO bioavailability, and cardiac biomarkers. These results suggest the therapeutic potential of NFESEPG in managing hypertension and related cardiovascular complications.

Effect of lipopolysaccharide on the development of oxidativenitrosative stress in salivary glands and soft periodontal tissues of rats under conditions of water avoidance stress

Introduction and aim. Violation in the salivary glands will inevitably cause changes in periodontium, and periodontitis can disrupt the functioning of the salivary glands. The purpose of the work is to evaluate changes in NO-synthase and arginase activities, pro- and antioxidant balance in rat salivary glands and soft periodontal tissues during administration of bacterial lipopolysaccharide (LPS) and water avoidance stress (WAS) modeling. Material and methods. The experiment was performed on 24 rats. The animals were divided into 4 groups: control, WAS, animals injected intraperitoneally with 0.4 μg/kg of bacterial LPS of Salmonella typhi, WAS+LPS. Results. Water avoidance stress led to decrease of inducible NO-synthase (iNOS) activity in salivary glands by 1.63 times, but decreased arginase activity by 1.15 times, superoxide production increased by 1.53 times, catalase activity decreased by 1.2 times, and malonic dialdehyde (MDA) increased by 1.19 times compared to the control. Lipopolysaccharide led to increase of constitutive NO-synthases (cNOS) activity in salivary glands by 1.48 times, but decreased arginase activity by 6.15 times, catalase activity increased by 2.6 times and superoxide dismutase activity decreased by 2.74 times, and MDA increased by 6.84 times compared to the control. Water avoidance stress + LPS in salivary glands led to decrease of cNOS and arginase activity by 1.09 and 1.19 times, respectively, superoxide production increased by 1.88 times, catalase and superoxide dismutase activity decreased by 1.06 times and 1.34 times, respectively, and MDA increased by 2.44 times compared to the control. Water avoidance stress led to increase of iNOS activity in periodontium by 1.44 times and arginase activity decreased by 1.37 times, superoxide production increased 1.32 times, catalase activity and superoxide dismutase activities decreased by 1.27 times and by 1.53 times, respectively, and MDA increased by 1.31 times compared to the control. Lipopolysaccharide led to increase of iNOS activity in the periodontium by 3.88 times, arginase activity decreased by 2.69 times, superoxide production increased 1.64 times, catalase activity increased by 4.32 times, and MDA increased by 4.51 times compared to the control. Water avoidance stress + LPS in periodontium led to increase of iNOS and cNOS activities by 1.95 times and 1.53, respectively, arginase activity decreased by 1.39 times, superoxide production increased 1.66 times, catalase activity increased by 1.11 times, and MDA increased by 1.53 times compared to the control. Conclusion. The combination of LPS and WAS leads to changes in NO production and oxidative stress in salivary glands and the periodontium.

HPLC phytochemical profiling, antioxidant activity and in vitro evaluation of inhibitory effects of Terminalia catappa stem bark extract on enzymes linked to diabetes, hypertensive vasoconstriction and erectile dysfunction

BackgroundTerminalia catappa is a traditional medicinal plant used for several ailments among the local folks. Among the locals, the stem bark is an important constituent of polyherbal remedies for the treatment of cancer and metabolic diseases; however, there is a paucity of scientific reports on it. This study aimed to evaluate the in vitro antidiabetic, antihypertensive and antierectile dysfunction effects of Terminalia catappa stem bark extract (TSBE). MethodsThe HPLC phytochemical profiling, total phenol content, total flavonoid content and antioxidant capacity of the extract were delineated. The inhibitory effects of TSBE on activities of α-glucosidase, α-amylase, acetylcholinesterase (AChE), arginase, phosphodiesterase-5′ (PDE-5′), angiotensin-converting enzyme (ACE) and ecto-5 nucleotidase (Ecto-5-NTD) were estimated following standard procedures. ResultsHPLC of TSBE profiled ferulic acid, gallic acid, caffeic acid, catechin, rutin, p-coumaric acid, chlorogenic acid, kaempferol, apiginin and quercetin. TSBE had IC50 values of 49.19 µg/mL and 55.42 µg/mL in terms of scavenging DPPH and NO radicals, respectively. The TSBE inhibited α-glucosidase and α-amylase activities with IC50 values of 71.53 µg/mL and 105.11 µg/mL, respectively. The inhibitory effects of TSBE on AChE, arginase, PDE-5′, and ACE revealed IC50 values higher than that of standards. TSBE demonstrated a stimulatory effect on ecto-5-NTD activity. ConclusionTSBE revealed promising antioxidant, antidiabetic, antihypertensive and antierectile dysfunction (anti-ED) properties which may be associated with the bioactive compounds present in the extract.

Sensing of an HIV-1-Derived Single-Stranded RNA-Oligonucleotide Induces Arginase 1-Mediated Tolerance.

Small synthetic oligodeoxynucleotides (ODNs) can mimic microbial nucleic acids by interacting with receptor systems and promoting immunostimulatory activities. Nevertheless, some ODNs can act differently on the plasmacytoid dendritic cell (pDC) subset, shaping their immunoregulatory properties and rendering them suitable immunotherapeutic tools in several clinical settings for treating overwhelming immune responses. We designed HIV-1-derived, DNA- and RNA-based oligonucleotides (gag, pol, and U5 regions) and assessed their activity in conferring a tolerogenic phenotype to pDCs in skin test experiments. RNA-but not DNA-oligonucleotides are capable of inducing tolerogenic features in pDCs. Interestingly, sensing the HIV-1-derived single-stranded RNA-gag oligonucleotide (RNA-gag) requires both TLR3 and TLR7 and the engagement of the TRIF adaptor molecule. Moreover, the induction of a suppressive phenotype in pDCs by RNA-gag is contingent upon the induction and activation of the immunosuppressive enzyme Arginase 1. Thus, our data suggest that sensing of the synthetic RNA-gag oligonucleotide in pDCs can induce a suppressive phenotype in pDCs, a property rendering RNA-gag a potential tool for therapeutic strategies in allergies and autoimmune diseases.