Arginase Research Articles

An experimental in silico study on COVID-19: Response of neutrophil-related genes to antibiotics.

Background and AimsAll components of the immune system are involved in alleviating severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection. Further research is required to provide detailed insights into COVID‐19‐related immune compartments and pathways. In addition, a significant percentage of hospitalized COVID‐19 patients suspect bacterial infections and antimicrobial resistance occurs following antibiotics treatment. The aim of this study was to evaluate the possible effects of antibiotics on the response of neutrophil‐related genes in SARS‐CoV‐2 patients by an experimental in silico study.MethodsThe two data sets GSE1739 and GSE21802 including 10 SARS positive patients and 35 influenza A (H1N1) patients were analyzed, respectively. Differentially expressed genes (DEGs) between these two data sets were determined by GEO2R analysis and the Venn diagram online tool. After determining the hub genes involved in immune responses, the expression of these genes in 30 COVID‐19 patients and 30 healthy individuals was analyzed by real‐time polymerase chain reaction (PCR). All patients received antibiotics, including levofloxacin, colistin, meropenem, and ceftazidime.ResultsGEO2R analysis detected 240 and 120 DEGs in GSE21802 and GSE1739, respectively. Twenty DEGs were considered as enriched hub genes involved in immune processes such as neutrophil degranulation, neutrophil activation, and antimicrobial humoral response. The central nodes were attributed to the genes of neutrophil elastase (ELANE), arginase 1 (ARG‐1), lipocalin 2 (LCN2), and defensin 4 (DEFA4). Compared to the healthy subjects, the expression of LCN2 and DEFA4 were significantly reduced in COVID‐19 patients. However, no significant differences were observed in the ELANE and AGR‐1 levels between COVID‐19 subjects and the control group.ConclusionsActivation and degranulation of neutrophils were observed mainly in SARS, and H1N1 infection processes and antibiotics administration could affect neutrophil activity during viral infection. It can be suggested that antibiotics can decrease inflammation by restoring the expression of neutrophil‐related genes in COVID‐19 patients.

Transcriptomic Analysis of Gill and Hepatopancreas in Razor Clam (Sinonovacula constricta) Exposed to Acute Ammonia

Accumulation of excessive ammonia is a big threat to aquatic animals, which causes adverse effects on the health, production reduction, and even high mortality. The razor clam Sinonovacula constricta, a bivalve living in intertidal mudflat with a deep-burrowing lifestyle, often faces a high concentration of ambient ammonia. However, there is less available information concerning the toxic effects of ammonia on razor clam and its molecular mechanisms of adaptation to ammonia stress. The aim of this study was to investigate the effects of ammonia exposure on the gill and hepatopancreas of razor clam by transcriptome sequencing. The results showed that the median lethal concentration of ammonia was 244.55 mg/L for 96 h. A total of 1,415 and 306 differentially expressed genes (DEGs) were identified in the gill and hepatopancreas, respectively. The functional annotation showed that DEGs of the gill were mainly involved in the regulation of nitrogen compound metabolic process, nitrogen compound transport, and amide transport. The DEGs of the hepatopancreas were mostly enriched in oxidation-reduction process, response to stress, and amine metabolic process. The expression levels of NH3/NH4+ transporting channels and H+ excreting-related genes, including Rhesus glycoproteins (Rh), Na+/K+-ATPase (NKA), Na+/H+ exchanger, V-ATPase (VHA), and carbonic anhydrase (CA), were upregulated significantly in the gill (p < 0.05). In addition, the expression levels of glutamine and urea synthesis-related genes that played vital roles in ammonia detoxification, such as glutamine synthetase (GS), arginase (ARG), and argininosuccinate synthetase (ASS), were also increased obviously in the hepatopancreas (p < 0.05). Taken together, our results indicate that the synergistic action of ammonia excretion in the gill and ammonia metabolism in the hepatopancreas might be the mechanism through which the clams tolerate to environmental ammonia. This study provides a molecular basis for the better evaluation of the responding mechanism of ammonia tolerance.

Physical Interaction between Embryonic Stem Cell-Expressed Ras (ERas) and Arginase-1 in Quiescent Hepatic Stellate Cells.

Embryonic stem cell-expressed Ras (ERas) is an atypical constitutively active member of the Ras family and controls distinct signaling pathways, which are critical, for instance, for the maintenance of quiescent hepatic stellate cells (HSCs). Unlike classical Ras paralogs, ERas has a unique N-terminal extension (Nex) with as yet unknown function. In this study, we employed affinity pull-down and quantitative liquid chromatography-tandem mass spectrometry (LC–MS/MS) analyses and identified 76 novel binding proteins for human and rat ERas Nex peptides, localized in different subcellular compartments and involved in various cellular processes. One of the identified Nex-binding proteins is the nonmitochondrial, cytosolic arginase 1 (ARG1), a key enzyme of the urea cycle and involved in the de novo synthesis of polyamines, such as spermidine and spermine. Here, we show, for the first time, a high-affinity interaction between ERas Nex and purified ARG1 as well as their subcellular colocalization. The inhibition of ARG1 activity strikingly accelerates the activation of HSCs ex vivo, suggesting a central role of ARG1 activity in the maintenance of HSC quiescence.

Myeloid Diagnostic and Prognostic Markers of Immune Suppression in the Blood of Glioma Patients

BackgroundAlthough gliomas are confined to the central nervous system, their negative influence over the immune system extends to peripheral circulation. The immune suppression exerted by myeloid cells can affect both response to therapy and disease outcome. We analyzed the expansion of several myeloid parameters in the blood of low- and high-grade gliomas and assessed their relevance as biomarkers of disease and clinical outcome.MethodsPeripheral blood was obtained from 134 low- and high-grade glioma patients. CD14+, CD14+/p-STAT3+, CD14+/PD-L1+, CD15+ cells and four myeloid-derived suppressor cell (MDSC) subsets, were evaluated by flow cytometry. Arginase-1 (ARG1) quantity and activity was determined in the plasma. Multivariable logistic regression model was used to obtain a diagnostic score to discriminate glioma patients from healthy controls and between each glioma grade. A glioblastoma prognostic model was determined by multiple Cox regression using clinical and myeloid parameters.ResultsChanges in myeloid parameters associated with immune suppression allowed to define a diagnostic score calculating the risk of being a glioma patient. The same parameters, together with age, permit to calculate the risk score in differentiating each glioma grade. A prognostic model for glioblastoma patients stemmed out from a Cox multiple analysis, highlighting the role of MDSC, p-STAT3, and ARG1 activity together with clinical parameters in predicting patient’s outcome.ConclusionsThis work emphasizes the role of systemic immune suppression carried out by myeloid cells in gliomas. The identification of biomarkers associated with immune landscape, diagnosis, and outcome of glioblastoma patients lays the ground for their clinical use.

A study of arginase-1 activity and lipid profile in patients with myocardial infarction

Myocardial necrosis caused by ischemia is called a myocardial infarction (MI). which interrupts coronary blood supply. When the oxygen supply to the heart is insufficient to meet metabolic demands, myocardial ischemia occurs. Atherosclerosis, which obstructs the coronary arteries, is the most common underlying cause of myocardial ischemia. The role of arginase-1 (ARG-1) and serum lipids in the pathogenesis of myocardial infarction is becoming clearer. This study aims to see if there is a link between ARG-1 activity and MI in the Iraqi population. Between the first of November 2021 and the first of February 2022, 90 people were separated into two groups: 45 patients with MI and 45 healthy controls. Human ARG-1 was measured in serum blood using the ELISA method. The serum lipid was measured using the spectrophotometry technique. The current investigation discovered a substantial (p=0.01) rise in ARG-1 concentration compared to control groups, as well as a significant difference in blood lipid content between patients and control groups (p<0.05). Finally, ARG-1 may have a role to play role in the pathogenesis of MI.

Flow Cytometric Characterization of Macrophages Infected in vitro with Salmonella enterica Serovar Typhimurium Expressing Red Fluorescent Protein.

Macrophages are important for host defense against intracellular pathogens like Salmonella and can be differentiated into two major subtypes. M1 macrophages, which are pro-inflammatory and induce antimicrobial immune effector mechanisms, including the expression of inducible nitric oxide synthase (iNOS), and M2 macrophages, which exert anti-inflammatory functions and express arginase 1 (ARG1). Through the process of phagocytosis, macrophages contain, engulf, and eliminate bacteria. Therefore, they are one of the first lines of defense against Salmonella. Infection with Salmonella leads to gastrointestinal disorders and systemic infection, termed typhoid fever. For further characterization of infection pathways, we established an in vitro model where macrophages are infected with the mouse Salmonella typhi correlate Salmonella enterica serovar Typhimurium ( S. tm), which additionally expresses red fluorescent protein (RFP). This allows us to clearly characterize macrophages that phagocytosed the bacteria, using multi-color flow cytometry. In this protocol, we focus on the in vitro characterization of pro- and anti-inflammatory macrophages displaying red fluorescent protein-expressing Salmonella enterica serovar Typhimurium, by multi-color flow cytometry.

Hyperthyroidism exacerbates ischemic reperfusion injury in the kidney.

Thyroid hormones are critical regulators of vertebrate development and metabolism. Under hyperthyroid conditions, excess thyroid hormones induce expression of several enzymes and activities via activation of ligand-bound thyroid hormone receptors (TRs). Arginase (ARG) is downstream of a ligand-bound TR and overexpression of ARG2 induces the production of reactive oxygen species and subsequent exacerbation of kidney ischemia/reperfusion (I/R) injury. To clarify the association between I/R-induced kidney injury and hyperthyroidism, mice were pretreated with L-thyroxine (LT4) or vehicle alone, then subjected to I/R. Proximal tubular cell-specific conditional knockout of thyroid hormone receptor β (TRβcKO) mice was generated and the effects of I/R were analyzed. Hyperthyroidism enhanced tubular damage and fibrosis in the kidneys of mice after I/R. Hyperthyroidism induced tubular cell necroptosis following inflammatory cell accumulation in the kidney after I/R. ARG2 expressions and reactive oxygen species accumulated in the kidneys of hyperthyroid mice after I/R, but these changes were ameliorated in the kidneys of TRβcKO mice. Hyperthyroidism-enhanced kidney injury was ameliorated in the kidney of TRβcKO mice after I/R. These results suggest that excess thyroid hormones are disadvantageous for the kidney under ischemic stress. Overt hypothyroidism represents a severe thyroid hormone deficiency disease that requires LT4 treatment, while overreplacement or iatrogenic thyrotoxicosis might cause kidney injury.

CD15+ Bone Marrow-derived Cells Are Regulators of Immune Response in ARG1-producing Colorectal Cancer Cells.

Bone marrow-derived cells regulate the antitumor functions of tumor infiltrating lymphocytes (TILs) through arginase 1 (ARG1)-dependent metabolism. This study examines which ARG1-producing lineage is responsible for the inhibitory function of TILs. Multiplexed immunohistochemistry was performed for CD11b, CD163, CD68, and CD15, together with ARG1 expression and CD3+ TIL infiltration estimation in human colorectal cancer specimens. Stratified survival analyses demonstrated that a large number of CD3+ TILs is a favorable prognostic factor in subgroups with a high level of ARG1+ infiltration and in the subgroup with a low level of ARG1- CD15+ infiltration. Calculation of the ARG1+/ARG1- ratio demonstrated that CD3+ TIL infiltration was prognostic in the subgroup with a low ARG1+/ARG1- ratio for CD15+ cells, contrary to other lineages. Tumor infiltrating CD15+ cells, the majority of which show polymorphonuclear features, are responsible for the ARG1-dependent T-cell dysfunction in human colorectal cancer.

Diagnostic sensitivity of arginase, alpha-1 antitrypsin and alpha-fetoprotein in hepatitis patients

Chronic hepatitis C virus (HCV) and hepatocellular carcinoma (HCC) are common liver diseases that lead to death in Egypt, especially in men. The current study aimed to evaluate the diagnostic sensitivity of arginase (ARG) activity, alpha-1 antitrypsin (AAT), and alpha-fetoprotein (AFP) in the sera of patients with HCV (with & without viremia) and HCC. A total of 190 men classified as 40 healthy used as control (G1), 100 infected with HCV (subdivided into 50 with viremia (G2) and 50 without viremia (G3), and 50 with HCC (G4). The activity of ARG significantly decreased in HCV and HCC groups along with significant elevation in the level of AAT and AFP as compared with the control. Although a non-significant variation was scored in AST/ALT, significant differences were observed among AST/ARG and ARG/ALT in the pathogenic groups as compared with the healthy group. Moreover, significant variations in ARG, AAT, AFP, AST/ARG, and ARG/ALT were observed between viremia and non-viremia. Although AFP scored significant change among the viremia and HCC, the rest parameters scored non-significant changes between both groups. Furthermore, a receiver operating characteristic curve (ROC) showed the diagnostic ability for the selected parameters with high sensitivity and multiple linear regressions exhibited good associations between those parameters. These findings suggest the using possibility of ARG, AAT, and AFP in the diagnosis and/or follow-up of patients with HCV or HCC.

Study on the effect of sevoflurane on the cognitive function of aged rats based on the activation of cortical microglia.

Postoperative cognitive dysfunction (POCD) is a common clinical manifestation that is a severe complication characterized by decreased learning abilityand deterioration of memory following anesthesia and surgery. However, the precise mechanisms of POCD are not completely understood. Rats were divided into blank control group (Con, n = 12)and sevoflurane group (Sev, n = 12). Morris water maze test was performed to evaluate the ability of learning and memory in two groups of rats; immunohistochemical staining was used to detect the expression of ion calcium-binding adaptor molecule-1 (Iba-1) in rat prefrontal cortex (PFC); Western blot analysis was applied respectively to investigate Iba-1, inducible nitric oxide synthase (iNOS), arginase-1 (ARG1), inflammatory cytokines interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) expression; The expression of iNOS, ARG1, IL-1β, and TNF-α in sera of rats was detected by enzyme-linked immunosorbent assay. We found that sevoflurane induced learning and memory impairment assessed by morris water maze test, anesthesia up-regulated the expression of iNOS, IL-1β and TNF-α inflammasome in microglia, as indicated by increased activation of Iba-1 and reduced the level of ARG1 in the PFC. We conclude that the cognitive function of rats after inhaling anesthesia was likely associated with M1/M2 polarization of microglia, which was triggered by sevoflurane.

Abstract PO-028: Pancreatic ductal adenocarcinoma is dependent on an unconventional pathway for polyamine synthesis

Abstract Targeting altered metabolism in pancreatic ductal adenocarcinoma (PDAC) has been an area of extensive investigation for over a decade now. A major hurdle however, for most anti-tumor metabolic strategies, is the high risk for toxicity, given the essential roles of metabolic pathways in the maintenance of normal tissue homeostasis. Indeed, this has been the case for targeting polyamines in cancers. Polyamines are small, highly positively charged molecules involved in multiple fundamental processes of cell growth and survival, including the synthesis of nucleic acids, modifications of chromatin structure, gene transcription and mRNA translation. Polyamine levels are significantly increased in many cancers, including PDAC. Prior anti-tumor strategies focused on pharmacological inhibition of the rate-limiting enzyme of polyamine synthesis, ornithine decarboxylase (ODC1) with little success, partially due to risk of harming normal tissues at higher drug doses. In this project, using both in vitro and in vivo mouse models of PDAC, we identified a dependency of PDAC on an unconventional way for the synthesis of the polyamine precursor ornithine, specifically from glutamine via ornithine aminotransferase (OAT); this is in contrast to its synthesis in most adult normal tissues from arginine via arginase (ARG) activity. We also identified potential key players mediating the induction of this metabolic pathway via KRAS, the main oncogenic driver in PDAC and are currently characterizing the downstream effects of polyamines on pancreatic tumor cells. The high dependency of PDAC, compared to normal tissue, on de novo ornithine synthesis via OAT provides an attractive therapeutic window for treating pancreatic cancer patients with minimal toxicity. Citation Format: Min-Sik Lee, Insia Naqvi, Courtney Dennis, Lucas Dailey, Alireza Lorzadeh, Tamara Zaytouni, Ashley Adler, Daniel S. Hitchcock, Lin Lin, Unmesh Jadhav, Clary B. Clish, Nada Y. Kalaany. Pancreatic ductal adenocarcinoma is dependent on an unconventional pathway for polyamine synthesis [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2021 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2021;81(22 Suppl):Abstract nr PO-028.

RETRACTED: Modulation of macrophage phenotype through controlled release of interleukin-4 from gelatine coatings on titanium surfaces.

Pro-inflammatory phenotype (M1) macrophages initiate angiogenesis, while their prolonged activation can induce chronic inflammation. Anti-inflammatory phenotype (M2) macrophages promote vessel maturation and tissue regeneration. Biomaterials which can promote M2 polarisation after appropriate inflammation should enhance angiogenesis and wound healing. Herein, Interleukin-4 (IL-4), an anti-inflammatory cytokine, was adsorbed onto a titanium surface. Then, a genipin cross-linked gelatine hydrogel was coated onto the surface to delay IL-4 release. The cross-linking degree of the hydrogel was modulated by the different amount of genipin to control release of IL-4. When 0.7 wt% (weight %) genipin was used as a cross-linker, the sample (GG07-I) released less IL-4 within the first several days, followed by a sustained release time to 14 d. Meanwhile, the release rate of IL-4 in GG07-I reached a peak between 3 d and 7 d. In culture with macrophages in vitro, GG07-I and GG07 exhibited good cytocompatibility. The phenotypical switch of macrophages stimulated by the samples was determined by FACS, ELISA and PCR. Macrophages cultured with GG07-I, GG07 and PT were firstly activated to the M1 phenotype by interferon-gamma (IFN-γ). Then, due to the release of IL-4 in 5 to 7 d, GG07-I enhanced CD206, increased the secretion and gene expression of M2 marker, such as interleukin-10 (IL-10), arginase-1 (ARG-1) and platelet derived growth factor-BB (PDGF- BB). GG07-I prompted the switch from M1 to M2 phenotype. Those appropriate secretion of cytokines would benefit both vascularisation and osseointegration. Thus, the biomaterial directing inflammatory reaction has good prospects for clinical treatments.

Preclinical investigation of Pegylated arginase 1 as a treatment for retina and brain injury

Arginase 1 (A1) is the enzyme that hydrolyzes the amino acid, L-arginine, to ornithine and urea. We have previously shown that A1 deletion worsens retinal ischemic injury, suggesting a protective role of A1. In this translational study, we aimed to study the utility of systemic pegylated A1 (PEG-A1, recombinant human arginase linked to polyethylene glycol) treatment in mouse models of acute retinal and brain injury. Cohorts of WT mice were subjected to retinal ischemia-reperfusion (IR) injury, traumatic optic neuropathy (TON) or brain cerebral ischemia via middle cerebral artery occlusion (MCAO) and treated with intraperitoneal injections of PEG-A1 or vehicle (PEG only). Drug penetration into retina and brain tissues was measured by western blotting and immunolabeling for PEG. Neuroprotection was measured in a blinded fashion by quantitation of NeuN (neuronal marker) immunolabeling of retina flat-mounts and brain infarct area using triphenyl tetrazolium chloride (TTC) staining. Furthermore, ex vivo retina explants and in vitro retina neuron cultures were subjected to oxygen-glucose deprivation (OGD) followed by reoxygenation (R) and treated with PEG-A1. PEG-A1 given systemically did not cross the intact blood-retina/brain barriers in sham controls but reached the retina and brain after injury. PEG-A1 provided neuroprotection after retinal IR injury, TON and cerebral ischemia. PEG-A1 treatment was also neuroprotective in retina explants subjected to OGD/R but did not improve survival in retinal neuronal cultures exposed to OGD/R. In summary, systemic PEG-A1 administration is neuroprotective and provides an excellent route to deliver the drug to the retina and the brain after acute injury.

Screening of differentially expressed proteins in placentas from patients with late-onset preeclampsia.

Preeclampsia (PE) is a severe disease that endangers the safety of mothers and fetuses worldwide. In the absence of specific treatments, more studies on novel predictive and diagnostic biomarkers for PE are required. Data-independent acquisition proteomics, with five biological replicates, was used to investigate the protein expression profiles of placental tissues from patients with PE and normal pregnant women. In total, 52 differentially expressed proteins (DEPs) were identified, 34 of them were upregulated and 18 downregulated. Bioinformatics analyses revealed that PE was associated with multiple GO terms and KEGG pathways. Arginase-1 (ARG1), ferritin light chain (FTL), and RNA cytidine acetyltransferase (NAT10) were identified as hub proteins, which were further validated in placental tissues and maternal plasma by western blot and ELISA. FTL expression was significantly lower in the placental tissues and early and late pregnancy plasma of patients with PE compared to that in normal pregnant women. This study is the first to propose that FTL may be a potential predictive and diagnostic biomarker for PE; it provides a proteomics insight for understanding the pathological mechanism of this disease.

Arginase Signalling as a Key Player in Chronic Wound Pathophysiology and Healing.

Arginase (ARG) represents an important evolutionarily conserved enzyme that is expressed by multiple cell types in the skin. Arg acts as the mediator of the last step of the urea cycle, thus providing protection against excessive ammonia under homeostatic conditions through the production of L-ornithine and urea. L-ornithine represents the intersection point between the ARG-dependent pathways and the urea cycle, therefore contributing to cell detoxification, proliferation and collagen production. The ARG pathways help balance pro- and anti-inflammatory responses in the context of wound healing. However, local and systemic dysfunctionalities of the ARG pathways have been shown to contribute to the hindrance of the healing process and the occurrence of chronic wounds. This review discusses the functions of ARG in macrophages and fibroblasts while detailing the deleterious implications of a malfunctioning ARG enzyme in chronic skin conditions such as leg ulcers. The review also highlights how ARG links with the microbiota and how this impacts on infected chronic wounds. Lastly, the review depicts chronic wound treatments targeting the ARG pathway, alongside future diagnosis and treatment perspectives.

An Epidermal-Specific Role for Arginase1 during Cutaneous Wound Repair

Nonhealing wounds are a major area of unmet clinical need remaining problematic to treat. Improved understanding of prohealing mechanisms is invaluable. The enzyme arginase1 (ARG1) is involved in prohealing responses, with its role in macrophages best characterized. ARG1 is also expressed by keratinocytes; however, ARG1 function in these critical wound repair cells is not understood. We characterized ARG1 expression in keratinocytes during normal cutaneous repair and reveal de novo temporal and spatial expression at the epidermal wound edge. Interestingly, epidermal ARG1 expression was decreased in both human and murine delayed healing wounds. We therefore generated a keratinocyte-specific ARG1-null mouse model (K14-cre;Arg1fl/fl) to explore arginase function. Wound repair, linked to changes in keratinocyte proliferation, migration, and differentiation, was significantly delayed in K14-cre;Arg1fl/fl mice. Similarly, using the arginase inhibitor N(omega)-hydroxy-nor-L-arginine, human in vitro and ex vivo models further confirmed this finding, revealing the importance of the downstream polyamine pathway in repair. Indeed, restoring the balance in ARG1 activity through the addition of putrescine proved beneficial in wound closure. In summary, we show that epidermal ARG1 plays, to our knowledge, a previously unreported intrinsic role in cutaneous healing, highlighting epidermal ARG1 and the downstream mediators as potential targets for the therapeutic modulation of wound repair.

Oral Administration of Cryptotanshinone-Encapsulated Nanoparticles for the Amelioration of Ulcerative Colitis.

Inappropriate macrophages phenotype transition contributes to the development of ulcerative colitis, and the poly (ethylene glycol)-block-poly (d, l-lactic acid) (PEG-PLA) nanoparticles delivery system can be utilized to improve the cryptotanshinone (CTS)-based therapy. We used a single emulsification method to prepare CTS-encapsulated nanoparticles (NPCTS). The therapeutic efficacy of NPCTS was evaluated in dextran sulfate sodium (DSS)-induced colitis mice. Then the proportion of total macrophages and M2-like macrophages were assayed with flow cytometry, and the relative content of pro-inflammatory cytokines in the colon was detected with Western blot. Bone-marrow-derived macrophages (BMDMs) were induced into M1-like macrophages, which were further incubated with NPCTS to repolarize into M2 subtype. Cryptotanshinone could induce the transition of M1 subtype to M2 subtype as indicated by up-regulated expression of arginase 1 (ARG1), interleukin (IL)-10, and CD206. In vivo, orally administrated NPCTS accumulated in the colon-infiltrated macrophages in colitis mice. It further revealed that NPCTS significantly alleviated colitis symptoms as indicated by increased body weight and colon length, decreased tumor necrosis factor (TNF)-α, IL-1β, and IL-6 content in the colon, and diminished total macrophage proportion (CD45+CD11b+F4/80+) and up-regulated M2 proportion (CD45+CD11b+F4/80+CD206hi). Oral administration of NPCTS could ameliorate ulcerative colitis with the conversion of M1-like macrophages to M2-like macrophages.

IL-6 is associated with expansion of myeloid-derived suppressor cells and enhanced immunosuppression in pancreatic adenocarcinoma patients.

Chronic inflammation favours the expansion of myeloid-derived suppressor cells (MDSCs) by secreting pro-inflammatory mediators. The role of MDSCs in mediating immunosuppression in pancreatic adenocarcinoma and in defining a premalignant route from chronic pancreatitis remains unclear. We aimed to study the immunosuppressive potential of all subsets of MDSCs and their correlation with inflammatory cytokines in pancreatic adenocarcinoma and chronic pancreatitis. Relative frequencies of MDSCs, immunosuppressive markers arginase-1 (ARG-1), programmed death-ligand 1 (PD-L1), reactive oxygen species (ROS) and cytokines in circulation and surgically resected local pancreatic tissue of chronic pancreatitis and pancreatic adenocarcinoma patients were analysed by multicolour flow cytometry and cytokine bead array, respectively. Levels of cytokines involved in MDSCs activation were analysed by ELISA, and the immunosuppressive nature of MDSCs was confirmed by T-cell suppression assay. Frequencies of circulating MDSCs and ARG-1, PD-L1, and ROS were significantly higher in pancreatic adenocarcinoma than healthy controls and showed a significant positive correlation with MDSCs burden in cancer tissue. Serum levels of cytokines IL-6, IL-8 and IL-10 were significantly elevated in pancreatic adenocarcinoma. IL-6 serum levels showed a significant positive correlation with frequencies of circulating MDSCs in pancreatic adenocarcinoma patients, and MDSCs mediated suppression of T-cell proliferation in vitro was associated with elevated IL-6 levels in the cell culture medium. Collectively, our results suggest that IL-6 plays a crucial role in the expansion of MDSCs and activating their immunosuppressive nature in pancreatic adenocarcinoma. The relative frequency of MDSCs in circulation can be used as a potential diagnostic biomarker for pancreatic cancer.

Breast cancer-derived GM-CSF regulates arginase 1 in myeloid cells to promote an immunosuppressive microenvironment.

Tumor-infiltrating myeloid cells contribute to the development of the immunosuppressive tumor microenvironment. Myeloid cell expression of arginase 1 (ARG1) promotes a protumor phenotype by inhibiting T cell function and depleting extracellular l-arginine, but the mechanism underlying this expression, especially in breast cancer, is poorly understood. In breast cancer clinical samples and in our mouse models, we identified tumor-derived GM-CSF as the primary regulator of myeloid cell ARG1 expression and local immune suppression through a gene-KO screen of breast tumor cell-produced factors. The induction of myeloid cell ARG1 required GM-CSF and a low pH environment. GM-CSF signaling through STAT3 and p38 MAPK and acid signaling through cAMP were required to activate myeloid cell ARG1 expression in a STAT6-independent manner. Importantly, breast tumor cell-derived GM-CSF promoted tumor progression by inhibiting host antitumor immunity, driving a significant accumulation of ARG1-expressing myeloid cells compared with lung and melanoma tumors with minimal GM-CSF expression. Blockade of tumoral GM-CSF enhanced the efficacy of tumor-specific adoptive T cell therapy and immune checkpoint blockade. Taken together, we show that breast tumor cell-derived GM-CSF contributes to the development of the immunosuppressive breast cancer microenvironment by regulating myeloid cell ARG1 expression and can be targeted to enhance breast cancer immunotherapy.

Functional characterization of arginine metabolic pathway enzymes in the antibacterial immune response of penaeid shrimp

Arginine metabolism pathway enzymes and products are important modulators of several physiological processes in animals, including immune response. Although some components of the arginine metabolic pathway have been reported in penaeid shrimps, no systematic study has explored all the key pathway enzymes involved in shrimp antimicrobial response. Here, we explored the role of the three key arginine metabolism enzymes (nitric-oxide synthase (NOS), arginase (ARG), agmatinase (AGM)) in Penaeus vannamei antimicrobial immunity. First, P. vannamei homologs of ARG and AGM (PvARG and PvAGM) were cloned and found to be evolutionally conserved with invertebrate counterparts. Transcript levels of PvARG, PvAGM, and PvNOS were ubiquitously expressed in healthy shrimp tissues and induced in hemocytes and hepatopancreas upon challenge with Gram-negative (Vibrio parahaemolyticus) and Gram-positive (Streptoccocus iniae) bacteria, suggesting their involvement in shrimp antimicrobial immune response. Besides, RNA interference knockdown and enzyme activity assay revealed an antagonistic relationship between PvARG/PvAGM and PvNOS, while this relationship was broken upon pathogen stimulation. Interestingly, knockdown of PvNOS increased Vibrio abundance in shrimp hemolymph, whereas knockdown of PvAGR reduced Vibrio abundance. Taken together, our present data shows that homologs of the key arginine metabolism pathway enzymes in penaeid shrimp (PvARG, PvAGM, and PvNOS) work synergistically and/or antagonistically to modulate antibacterial immune response.