Adrenergic Signaling in Muscularis Macrophages Limits Infection-Induced Neuronal Loss.

Enteric-associated neurons (EANs) are closely associated with immune cells and continuously monitor and modulate homeostatic intestinal functions, including motility and nutrient sensing. Bidirectional interactions between neuronal and immune cells are altered during disease processes such as neurodegeneration or irritable bowel syndrome. We investigated the effects of infection-induced inflammation on intrinsic EANs (iEANs) and the role of intestinal muscularis macrophages (MMs) in this context. Using murine models of enteric infections, we observed long-term gastrointestinal symptoms, including reduced motility and loss of excitatory iEANs, which was mediated by a Nlrp6- and Casp11-dependent mechanism, depended on infection history, and could be reversed by manipulation of the microbiota. MMs responded to luminal infection by upregulating a neuroprotective program via ß2-adrenergic receptor (ß2-AR) signaling and mediated neuronal protection through an arginase 1-polyamine axis. Our results identify a mechanism of neuronal death post-infection and point to a role for tissue-resident MMs in limiting neuronal damage.

Loss of CD4+ T cell-intrinsic arginase 1 accelerates Th1 response kinetics and reduces lung pathology during influenza infection.

Arginase 1 (Arg1), the enzyme catalyzing the conversion of arginine to ornithine, is a hallmark of IL-10-producing immunoregulatory M2 macrophages. However, its expression in T cells is disputed. Here, we demonstrate that induction of Arg1 expression is a key feature of lung CD4+ T cells during mouse in vivo influenza infection. Conditional ablation of Arg1 in CD4+ T cells accelerated both virus-specific T helper 1 (Th1) effector responses and its resolution, resulting in efficient viral clearance and reduced lung pathology. Using unbiased transcriptomics and metabolomics, we found that Arg1-deficiency was distinct from Arg2-deficiency and caused altered glutamine metabolism. Rebalancing this perturbed glutamine flux normalized the cellular Th1 response. CD4+ T cells from rare ARG1-deficient patients or CRISPR-Cas9-mediated ARG1-deletion in healthy donor cells phenocopied the murine cellular phenotype. Collectively, CD4+ T cell-intrinsic Arg1 functions as an unexpected rheostat regulating the kinetics of the mammalian Th1 lifecycle with implications for Th1-associated tissue pathologies.

Excessive Polyamine Generation in Keratinocytes Promotes Self-RNA Sensing by Dendritic Cells in Psoriasis.

Psoriasis is a chronic inflammatory disease whose etiology is multifactorial. The contributions of cellular metabolism to psoriasis are unclear. Here, we report that interleukin-17 (IL-17) downregulated Protein Phosphatase 6 (PP6) in psoriatic keratinocytes, causing phosphorylation and activation of the transcription factor C/EBP-ß and subsequent generation of arginase-1. Mice lacking Pp6 in keratinocytes were predisposed to psoriasis-like skin inflammation. Accumulation of arginase-1 in Pp6-deficient keratinocytes drove polyamine production from the urea cycle. Polyamines protected self-RNA released by psoriatic keratinocytes from degradation and facilitated the endocytosis of self-RNA by myeloid dendritic cells to promote toll-like receptor-7 (TLR7)-dependent RNA sensing and IL-6 production. An arginase inhibitor improved skin inflammation in murine and non-human primate models of psoriasis. Our findings suggest that urea cycle hyperreactivity and excessive polyamine generation in psoriatic keratinocytes promote self-RNA sensation and PP6 deregulation in keratinocytes is a pivotal event that amplifies the inflammatory circuits in psoriasis.

Tissue-Resident Group 2 Innate Lymphoid Cells Differentiate by Layered Ontogeny and In Situ Perinatal Priming.

The perinatal period is a critical window for distribution of innate tissue-resident immune cells within developing organs. Despite epidemiologic evidence implicating the early-life environment in the risk for allergy, temporally controlled lineage tracing of group 2 innate lymphoid cells (ILC2s) during this period remains unstudied. Using complementary fate-mapping approaches and reporters for ILC2 activation, we show that ILC2s appeared in multiple organs during late gestation like tissue macrophages, but, unlike the latter, a majority of peripheral ILC2 pools were generated de novo during the postnatal window. This period was accompanied by systemic ILC2 priming and acquisition of tissue-specific transcriptomes. Although perinatal ILC2s were variably replaced across tissues with age, the dramatic increases in tissue ILC2s following helminth infection were mediated through local expansion independent of de novo generation by bone marrow hematopoiesis. We provide comprehensive temporally controlled fate mapping of an innate lymphocyte subset with notable nuances as compared to tissue macrophage ontogeny.

L-arginine homeostasis governs adult neural stem cell activation by modulating energy metabolism in vivo.

Neurogenesis in the developing and adult brain is intimately linked to remodeling of cellular metabolism. However, it is still unclear how distinct metabolic programs and energy sources govern neural stem cell (NSC) behavior and subsequent neuronal differentiation. Here, we found that adult mice lacking the mitochondrial urea metabolism enzyme, Arginase-II (Arg-II), exhibited NSC overactivation, thereby leading to accelerated NSC pool depletion and decreased hippocampal neurogenesis over time. Mechanistically, Arg-II deficiency resulted in elevated L-arginine levels and induction of a metabolic shift from glycolysis to oxidative phosphorylation (OXPHOS) caused by impaired attachment of hexokinase-I to mitochondria. Notably, selective inhibition of OXPHOS ameliorated NSC overactivation and restored abnormal neurogenesis in Arg-II deficient mice. Therefore, Arg-II-mediated intracellular L-arginine homeostasis directly influences the metabolic fitness of neural stem cells that is essential to maintain neurogenesis with age.

Arginase 1 and L-arginine coordinate fetal lung development and the initiation of labor in mice.

Fetal development and parturition are precisely regulated processes that involve continuous crosstalk between the mother and the fetus. Our previous discovery that wild-type mice carrying steroid receptor coactivator (Src)-1 and Src-2 double-deficient fetuses exhibit impaired lung development and delayed labor, which indicates that the signals for parturition emanate from the fetus. In this study, we perform RNA sequencing and targeted metabolomics analyses of the lungs from fetal Src-1/-2 double-knockout mice and find that expression of arginase 1 (Arg1) is significantly decreased, accompanied by increased levels of the Arg1 substrate L-arginine. Knockdown of Arg1 in the lungs of fetal mice induces apoptosis of epithelial cells and dramatically delays initiation of labor. Moreover, treatment of human myometrial smooth muscle cells with L-arginine significantly inhibits spontaneous contractions by attenuating activation of NF-κB and downregulating expression of contraction-associated protein genes. Transcription factors GR and C/EBPß increase transcription of Arg1 in an Src-1/Src-2-dependent manner. These findings provide new evidence that fetus-derived factors may play dual roles in coordinating fetal lung development and the initiation of labor.

Decreased Memory and Learning Ability Mediated by Bmal1/M1 Macrophages/Angptl2/Inflammatory Cytokine Pathway in Mice Exposed to Long-Term Blue Light Irradiation.

Humans are persistently exposed to massive amounts of blue light via sunlight, computers, smartphones, and similar devices. Although the positive and negative effects of blue light on living organisms have been reported, its impact on learning and memory remains unknown. Herein, we examined the effects of widespread blue light exposure on the learning and memory abilities of blue light-exposed mice. Ten-week-old male ICR mice were divided into five groups (five mice/group) and irradiated with blue light from a light-emitting diode daily for 6 months. After 6 months of blue light irradiation, mice exhibited a decline in memory and learning abilities, assessed using the Morris water maze and step-through passive avoidance paradigms. Blue light-irradiated mice exhibited a decreased expression of the clock gene brain and muscle arnt-like 1 (Bmal1). The number of microglia and levels of M1 macrophage CC-chemokine receptor 7 and inducible nitric oxide synthase were increased, accompanied by a decrease in M2 macrophage arginase-1 levels. Levels of angiopoietin-like protein 2 and inflammatory cytokines interleukin-6, tumor necrosis factor-α, and interleukin-1ß were elevated. Our findings suggest that long-term blue light exposure could reduce Bmal1 expression, activate the M1 macrophage/Angptl2/inflammatory cytokine pathway, induce neurodegeneration, and lead to a decline in memory.

Macrophage-derived Osteopontin (SPP1) Protects From Nonalcoholic Steatohepatitis.

BACKGROUND & AIMS: Nonalcoholic steatohepatitis (NASH) is characterized by steatosis, lobular inflammation, hepatocyte ballooning degeneration, and fibrosis, all of which increase the risk of progression to end-stage liver disease. Osteopontin (OPN, SPP1) plays an important role in macrophage (MF) biology, but whether MF-derived OPN affects NASH progression is unknown. METHODS: We analyzed publicly available transcriptomic datasets from patients with NASH, and used mice with conditional overexpression or ablation of Spp1 in myeloid cells and liver MFs, and fed them a high-fat, fructose, and cholesterol diet mimicking the Western diet, to induce NASH. RESULTS: This study demonstrated that MFs with high expression of SPP1 are enriched in patients and mice with nonalcoholic fatty liver disease (NAFLD), and show metabolic but not pro-inflammatory properties. Conditional knockin of Spp1 in myeloid cells (Spp1KI Mye) or in hepatic macrophages (Spp1KI LvMF) conferred protection, whereas conditional knockout of Spp1 in myeloid cells (Spp1ΔMye) worsened NASH. The protective effect was mediated by induction of arginase-2 (ARG2), which enhanced fatty acid oxidation (FAO) in hepatocytes. Induction of ARG2 stemmed from enhanced production of oncostatin-M (OSM) in MFs from Spp1KI Mye mice. OSM activated STAT3 signaling, which upregulated ARG2. In addition to hepatic effects, Spp1KI Mye also protected through sex-specific extrahepatic mechanisms. CONCLUSION: MF-derived OPN protects from NASH, by upregulating OSM, which increases ARG2 through STAT3 signaling. Further, the ARG2-mediated increase in FAO reduces steatosis. Therefore, enhancing the OPN-OSM-ARG2 crosstalk between MFs and hepatocytes may be beneficial for patients with NASH.

Red blood cells from patients with ST-elevation myocardial infarction and elevated C-reactive protein levels induce endothelial dysfunction.

Endothelial dysfunction is an early consequence of vascular inflammation and a driver of coronary atherosclerotic disease leading to myocardial infarction. The red blood cells (RBCs) mediate endothelial dysfunction in patients at cardiovascular risk, but their role in patients with acute myocardial infarction is unknown. This study aimed to investigate if RBCs from patients with ST-elevation myocardial infarction (STEMI) induced endothelial dysfunction and the role of systemic inflammation in this effect. RBCs from patients with STEMI and aged-matched healthy controls were co-incubated with rat aortic segments for 18h followed by evaluation of endothelium-dependent (EDR) and -independent relaxation (EIDR). RBCs and aortic segments were also analyzed for arginase and oxidative stress. The patients were divided into groups depending on C-reactive protein (CRP) levels at admission. RBCs from patients with STEMI and CRP levels >2 mg/L induced impairment of EDR, but not EIDR, compared to RBCs from STEMI and CRP <2 mg/L and healthy controls. Aortic expression of arginase 1 was increased following incubation with RBCs from patients with STEMI and CRP >2, and arginase inhibition prevented the RBC-induced endothelial dysfunction. RBCs from patients with STEMI and CRP >2 had increased reactive oxygen species compared to RBCs from patients with CRP <2 and healthy controls. Vascular inhibition of NADPH oxidases and increased dismutation of superoxide improved EDR. RBCs from patients with STEMI and low-grade inflammation induce endothelial dysfunction through a mechanism involving arginase 1 as well and increased RBC and vascular superoxide by NADPH oxidases.

Characterization, modeling, and anticancer activity of L.arginase production from marine Bacillus licheniformis OF2.

BACKGROUND: L-arginase, is a powerful anticancer that hydrolyzes L-arginine to L-ornithine and urea. This enzyme is widely distributed and expressed in organisms like plants, fungi, however very scarce from bacteria. Our study is based on isolating, purifying, and screening the marine bacteria that can produce arginase. RESULTS: The highest arginase producing bacteria will be identified by using microbiological and molecular biology methods as Bacillus licheniformis OF2. Characterization of arginase is the objective of this study. The activity of enzyme was screened, and estimated beside partial sequencing of arginase gene was analyzed. In silico homology modeling was applied to generate the protein's 3D structure, and COACH and COFACTOR were applied to determine the protein's binding sites and biological annotations based on the I-TASSER structure prediction. The purified enzyme was undergone an in vitro anticancer test. CONCLUSIONS: L-arginase demonstrated more strong anti-cancer cells with an IC50 of 21.4 ug/ml in a dose-dependent manner. L-arginase underwent another investigation for its impact on the caspase 7 and BCL2 family of proteins (BCL2, Bax, and Bax/Bcl2). Through cell arrest in the G1/S phase, L-arginase signals the apoptotic cascade, which is supported by a flow cytometry analysis of cell cycle phases.

Neither injury induced macrophages within the nerve, nor the environment created by Wallerian degeneration is necessary for enhanced in vivo axon regeneration after peripheral nerve injury.

BACKGROUND: Since the 1990s, evidence has accumulated that macrophages promote peripheral nerve regeneration and are required for enhancing regeneration in the conditioning lesion (CL) response. After a sciatic nerve injury, macrophages accumulate in the injury site, the nerve distal to that site, and the axotomized dorsal root ganglia (DRGs). In the peripheral nervous system, as in other tissues, the macrophage response is derived from both resident macrophages and recruited monocyte-derived macrophages (MDMs). Unresolved questions are: at which sites do macrophages enhance nerve regeneration, and is a particular population needed. METHODS: Ccr2 knock-out (KO) and Ccr2gfp/gfp knock-in/KO mice were used to prevent MDM recruitment. Using these strains in a sciatic CL paradigm, we examined the necessity of MDMs and residents for CL-enhanced regeneration in vivo and characterized injury-induced nerve inflammation. CL paradigm variants, including the addition of pharmacological macrophage depletion methods, tested the role of various macrophage populations in initiating or sustaining the CL response. In vivo regeneration, measured from bilateral proximal test lesions (TLs) after 2 d, and macrophages were quantified by immunofluorescent staining. RESULTS: Peripheral CL-enhanced regeneration was equivalent between crush and transection CLs and was sustained for 28 days in both Ccr2 KO and WT mice despite MDM depletion. Similarly, the central CL response measured in dorsal roots was unchanged in Ccr2 KO mice. Macrophages at both the TL and CL, but not between them, stained for the pro-regenerative marker, arginase 1. TL macrophages were primarily CCR2-dependent MDMs and nearly absent in Ccr2 KO and Ccr2gfp/gfp KO mice. However, there were only slightly fewer Arg1+ macrophages in CCR2 null CLs than controls due to resident macrophage compensation. Zymosan injection into an intact WT sciatic nerve recruited Arg1+ macrophages but did not enhance regeneration. Finally, clodronate injection into Ccr2gfp KO CLs dramatically reduced CL macrophages. Combined with the Ccr2gfp KO background, depleting MDMs and TL macrophages, and a transection CL, physically removing the distal nerve environment, nearly all macrophages in the nerve were removed, yet CL-enhanced regeneration was not impaired. CONCLUSIONS: Macrophages in the sciatic nerve are neither necessary nor sufficient to produce a CL response.

4R-cembranoid suppresses glial cells inflammatory phenotypes and prevents hippocampal neuronal loss in LPS-treated mice.

Chronic neuroinflammation has been implicated in neurodegenerative disease pathogenesis. A key feature of neuroinflammation is neuronal loss and glial activation, including microglia and astrocytes. 4R-cembranoid (4R) is a natural compound that inhibits hippocampal pro-inflammatory cytokines and increases memory function in mice. We used the lipopolysaccharide (LPS) injection model to study the effect of 4R on neuronal density and microglia and astrocyte activation. C57BL/6J wild-type mice were injected with LPS (5 mg/kg) and 2 h later received either 4R (6 mg/kg) or vehicle. Mice were sacrificed after 72 h for analysis of brain pathology. Confocal images of brain sections immunostained for microglial, astrocyte, and neuronal markers were used to quantify cellular hippocampal phenotypes and neurons. Hippocampal lysates were used to measure the expression levels of neuronal nuclear protein (NeuN), inducible nitrous oxide synthase (iNOS), arginase-1, thrombospondin-1 (THBS1), glial cell-derived neurotrophic factor (GDNF), and orosomucoid-2 (ORM2) by western blot. iNOS and arginase-1 are widely used protein markers of pro- and anti-inflammatory microglia, respectively. GDNF promotes neuronal survival, and ORM2 and THBS1 are astrocytic proteins that regulate synaptic plasticity and inhibit microglial activation. 4R administration significantly reduced neuronal loss and the number of pro-inflammatory microglia 72 h after LPS injection. It also decreased the expression of the pro-inflammatory protein iNOS while increasing arginase-1 expression, supporting its anti-inflammatory role. The protein expression of THBS1, GDNF, and ORM2 was increased by 4R. Our data show that 4R preserves the integrity of hippocampal neurons against LPS-induced neuroinflammation in mice.

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

BACKGROUND: Arginase 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 3'-O-glucoside inhibits arginase activity and activates nitric oxide synthase, thereby reducing M2-like macrophages while promoting M1-like macrophage polarization. METHODS: The natural compounds piceatannol 3'-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. RESULTS: PG/ICG@MP precisely targets the tumor site, with piceatannol 3'-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 3'-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. CONCLUSION: Our 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.

Red blood cell-derived arginase release in hemolytic uremic syndrome.

BACKGROUND: Hemolysis is a cardinal feature of hemolytic uremic syndrome (HUS) and during hemolysis excess arginase 1 is released from red blood cells. Increased arginase activity leads to reduced L-arginine, as it is converted to urea and L-ornithine, and thereby reduced nitric oxide bioavailability, with secondary vascular injury. The objective of this study was to investigate arginase release in HUS patients and laboratory models and correlate arginase levels to hemolysis and kidney injury. METHODS: Two separate cohorts of patients (n = 47 in total) with HUS associated with Shiga toxin-producing enterohemorrhagic E. coli (EHEC) and pediatric controls (n = 35) were investigated. Two mouse models were used, in which mice were either challenged intragastrically with E. coli O157:H7 or injected intraperitoneally with Shiga toxin 2. An in vitro model of thrombotic microangiopathy was developed in which Shiga toxin 2- and E. coli O157 lipopolysaccharide-stimulated human blood cells combined with ADAMTS13-deficient plasma were perfused over glomerular endothelial cells. Two group statistical comparisons were performed using the Mann-Whitney test, multiple groups were compared using the Kruskal-Wallis test followed by Dunn's procedure, the Wilcoxon signed rank test was used for paired data, or linear regression for continuous variables. RESULTS: HUS patients had excessively high plasma arginase 1 levels and activity (conversion of L-arginine to urea and L-ornithine) during the acute phase, compared to remission and controls. Arginase 1 levels correlated with lactate dehydrogenase activity, indicating hemolysis, as well as the need for dialysis treatment. Patients also exhibited high levels of plasma alpha-1-microglobulin, a heme scavenger. Both mouse models exhibited significantly elevated plasma arginase 1 levels and activity. Plasma arginase 1 levels correlated with lactate dehydrogenase activity, alpha-1-microglobulin and urea levels, the latter indicative of kidney dysfunction. In the in vitro model of thrombotic microangiopathy, bioactive arginase 1 was released and levels correlated to the degree of hemolysis. CONCLUSIONS: Elevated red blood cell-derived arginase was demonstrated in HUS patients and in relevant in vivo and in vitro models. The excessively high arginase levels correlated to the degree of hemolysis and kidney dysfunction. Thus, arginase inhibition should be investigated in HUS.

Broad-spectrum anti-cancer activity of fused human arginase variants.

The rapid increase in cancer cases worldwide necessitates the development of novel therapeutic approaches. Therapies targeting cancer's altered metabolism, especially those that deplete critical amino acids, have emerged as promising ones, some of which are already being used in clinical practice and many others are under development. This study reports the anti-cancer activity of two novel fused human arginase I (FHA) variants, FHA-3 and FHA-12, assessed using the NCI-60 human tumor cell line panel. Both variants have demonstrated a range of potencies in a single-dose assay (10 µM), but FHA-3 was found to be more potent with significant growth inhibition in most tested cell lines. To calculate 50% growth inhibition (GI50), FHA-3 was further evaluated in a five-dose assay, where notable anti-cancer activity was observed across the nine cancer types of the NCI-60 panel. Our results demonstrated the broad-spectrum anti-cancer activity of novel FHA variants, with FHA-3 being the most potent. Further studies elucidating its efficacy in animal models will help explore its therapeutic potential.

Tuberculous pleural effusion-induced Arg-1+ macrophage polarization contributes to lung cancer progression via autophagy signaling.

BACKGROUND: The association between tuberculous fibrosis and lung cancer development has been reported by some epidemiological and experimental studies; however, its underlying mechanisms remain unclear, and the role of macrophage (MФ) polarization in cancer progression is unknown. The aim of the present study was to investigate the role of M2 Arg-1+ MФ in tuberculous pleurisy-assisted tumorigenicity in vitro and in vivo. METHODS: The interactions between tuberculous pleural effusion (TPE)-induced M2 Arg-1+ MФ and A549 lung cancer cells were evaluated. A murine model injected with cancer cells 2 weeks after Mycobacterium bovis bacillus Calmette-Guérin pleural infection was used to validate the involvement of tuberculous fibrosis to tumor invasion. RESULTS: Increased CXCL9 and CXCL10 levels of TPE induced M2 Arg-1+ MФ polarization of murine bone marrow-derived MФ. TPE-induced M2 Arg-1+ MФ polarization facilitated lung cancer proliferation via autophagy signaling and E-cadherin signaling in vitro. An inhibitor of arginase-1 targeting M2 Arg-1+ MФ both in vitro and in vivo significantly reduced tuberculous fibrosis-induced metastatic potential of lung cancer and decreased autophagy signaling and E-cadherin expression. CONCLUSION: Tuberculous pleural fibrosis induces M2 Arg-1+ polarization, and M2 Arg-1+ MФ contribute to lung cancer metastasis via autophagy and E-cadherin signaling. Therefore, M2 Arg-1+ tumor associated MФ may be a novel therapeutic target for tuberculous fibrosis-induced lung cancer progression.

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.

Neurovascular dysfunction associated with erectile dysfunction persists after long-term recovery from simulations of weightlessness and deep space irradiation.

There has been growing interest within the space industry for long-duration manned expeditions to the Moon and Mars. During deep space missions, astronauts are exposed to high levels of galactic cosmic radiation (GCR) and microgravity which are associated with increased risk of oxidative stress and endothelial dysfunction. Oxidative stress and endothelial dysfunction are causative factors in the pathogenesis of erectile dysfunction, although the effects of spaceflight on erectile function have been unexplored. Therefore, the purpose of this study was to investigate the effects of simulated spaceflight and long-term recovery on tissues critical for erectile function, the distal internal pudendal artery (dIPA), and the corpus cavernosum (CC). Eighty-six adult male Fisher-344 rats were randomized into six groups and exposed to 4-weeks of hindlimb unloading (HLU) or weight-bearing control, and sham (0Gy), 0.75 Gy, or 1.5 Gy of simulated GCR at the ground-based GCR simulator at the NASA Space Radiation Laboratory. Following a 12-13-month recovery, ex vivo physiological analysis of the dIPA and CC tissue segments revealed differential impacts of HLU and GCR on endothelium-dependent and -independent relaxation that was tissue type specific. GCR impaired non-adrenergic non-cholinergic (NANC) nerve-mediated relaxation in the dIPA and CC, while follow-up experiments of the CC showed restoration of NANC-mediated relaxation of GCR tissues following acute incubation with the antioxidants mito-TEMPO and TEMPOL, as well as inhibitors of xanthine oxidase and arginase. These findings indicate that simulated spaceflight exerts a long-term impairment of neurovascular erectile function, which exposes a new health risk to consider with deep space exploration.

Fish arginase constrains excessive production of nitric oxide and limits mitochondrial damage during Aeromonas hydrophila infection.

Bacteria-enhanced inducible nitric oxide synthase (iNOS) overproduces nitric oxide (NO) leading to mitochondrial and cellular damage. In mammals, arginase (ARG), the enzyme consuming the same substrate l-arginine with iNOS, was believed to inhibit iNOS activity by competing the substrate. But in fish, this conception has been widely challenged. In this study, the gene expression using real-time quantitative PCR (RT-qPCR) technology showed that when stimulated by Aeromonas hydrophila (A. hydrophila), grass carp (gc) iNOS was up-regulated in head kidney monocytes/macrophages (M0/MФ), and its changes were not detected in the whole tissue of liver or spleen, showing a high degree of cell-specific expression pattern. At the same time, gcARG2 had a high basal expression in tissues and was up-regulated by A. hydrophila stimulation. Next, phthalaldehyde-primaquine reaction was first used in the determination of intracellular urea in fish cells. It was found that the induced gcARG2 led to an increase in the intracellular urea content. Moreover, urea and NO production in M0/MФ were increased in a substrate dose-dependent manner from 30 to 100 µM of l-arginine and reached the highest yield at 300 and 3000 µM of l-arginine, respectively. Furthermore, head kidney M0/MФ was cultured in RPMI1640 medium containing physiological concentration (500 µM) of l-arginine to evaluate the effect of ARG. Under A. hydrophila stimulation, treatment with the arginase inhibitor S-(2-boronoethyl)-l-cysteine (BEC) showed that inhibition of arginase could further enhance the NO production stimulated by A. hydrophila. This in turn led to a cumulation in peroxynitrite (ONOO-) content and an injury of the mitochondrial membrane potential. Our study showed for the first time that fish ARG in head kidney M0/MФ can limit excessive production of NO and harmful products by iNOS to maintain mitochondrial and cellular homeostasis.

New biomarkers for liver involvement by dengue infection in adult Vietnamese patients: a case-control study.

Liver injury with marked elevation of aspartate aminotransferase enzyme (AST) is commonly observed in dengue infection. To understand the pathogenesis of this liver damage, we compared the plasma levels of hepatic specific, centrilobular predominant enzymes (glutamate dehydrogenase, GLDH; glutathione S transferase-α, αGST), periportal enriched 4-hydroxyphenylpyruvate dioxygenase (HPPD), periportal predominant arginase-1 (ARG-1), and other non-specific biomarkers (paraoxonase-1, PON-1) in patients with different outcomes of dengue infection. This hospital-based study enrolled 87 adult dengue patients, stratified into three groups based on plasma AST levels (< 80, 80-400, > 400 U/L) in a 1:1:1 ratio (n = 40, n = 40, n = 40, respectively. The new liver enzymes in the blood samples from the 4th to 6th days of their illness were measured by commercial enzyme-linked immunosorbent assay (ELISA) or colorimetric kits. Based on the diagnosis at discharge days, our patients were classified as 40 (46%) dengue without warning signs (D), 35 (40.2%) dengue with warning signs (DWS), and 11 (12.6%) severe dengue (SD) with either shock (two patients) or AST level over 1000 U/L (nine patients), using the 2009 WHO classification. The group of high AST (> 400 U/L) also had higher ALT, GLDH, ARG-1, and HPPD than the other groups, while the high (> 400 U/L) and moderate (80-400 U/L) AST groups had higher ALT, αGST, ARG-1, and HPPD than the low AST group (< 80 U/L). There was a good correlation between AST, alanine aminotransferase enzyme (ALT), and the new liver biomarkers such as GLDH, αGST, ARG-1, and HPPD. Our findings suggest that dengue-induced liver damage initiates predominantly in the centrilobular area toward the portal area during the dengue progression. Moreover, these new biomarkers should be investigated further to explain the pathogenesis of dengue and to validate their prognostic utility.