Inosine protects against the development of diabetes in multiple-low-dose streptozotocin and nonobese diabetic mouse models of type 1 diabetes

Metabolic impairments associated with type 2 diabetes mellitus and the potential effects of exercise therapy: An exploratory randomized trial based on untargeted metabolomics

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a common condition that is characterized by metabolic impairments. Exercise therapy has proven effective in improving the physiological and psychological states of patients with T2DM; however, the influence of different exercise modalities on metabolic profiles is not fully understood. This study first aimed to investigate the metabolic changes associated with T2DM among patients and then to evaluate the potential physiological effects of different exercise modalities (Tai Chi and brisk walking) on their metabolic profiles.

METHODS

This study included 20 T2DM patients and 11 healthy subjects. Patients were randomly allocated to either the Tai Chi or walking group to perform Dijia simplified 24-form Tai Chi or brisk walking (80-100 m/min), with 90 minutes each time, three times per week for 12 weeks, for a total of 36 sessions. The healthy group maintained daily living habits without intervention. Glycemic tests were conducted at the baseline and after 12 weeks. Serum and urine samples were collected for untargeted metabolomic analyses at baseline and 12 weeks to examine the differential metabolic profiles between T2DM and healthy subjects, and the metabolic alterations of T2DM patients before and after exercise therapy.

RESULTS

Compared to the healthy group, T2DM patients exhibited metabolic disturbances in carbohydrates (fructose, mannose, galactose, glycolysis/gluconeogenesis), lipids (inositol phosphate), and amino acids (arginine, proline, cysteine, methionine, valine, leucine, and isoleucine) metabolism, including 20 differential metabolites in the serum and six in the urine. After exercise, the glycemic results showed insignificant changes. However, patients who practiced Tai Chi showed significant improvements in their post-treatment metabolic profiles compared to baseline, with nine serum and six urine metabolites, including branch-chained amino acids (BCAAs); while those in the walking group had significantly altered nine serum and four urine metabolites concerning steroid hormone biosynthesis and arachidonic acid metabolism compared to baseline.

CONCLUSION

T2DM patients displayed impaired carbohydrate, lipid, and amino acid metabolism, and exercise therapy improved their metabolic health. Different modalities may act through different pathways. Tai Chi may improve disrupted BCAAs metabolism, whereas brisk walking mainly regulates steroid hormone biosynthesis and arachidonic acid metabolism.

Rational engineering of an improved adenosine deaminase 2 enzyme for weaponizing T-cell therapies

Adenosine is a potent immunosuppressive metabolite that accumulates in the extracellular space within solid tumors and inhibits the antitumor function of native immune cell responses as well as chimeric antigen receptor (CAR) T-cell therapies. Here, we show that engineered human cells can degrade extracellular adenosine through secretion of adenosine deaminase (ADA) enzymes-a possible therapeutic enhancement for CAR T cells. We first determine that the high-activity ADA1 isoform is naturally intracellularly restricted and show that the addition of canonical or computationally predicted secretory peptides did not allow for improved secretion. We did, however, determine that the lower-activity ADA2 isoform is naturally secreted. Thus, we utilized phylogenetic-based structural comparisons to guide a mutational survey of ADA2 active site residues, which when coupled with a high-throughput screen for enhanced ADA2-mediated extracellular adenosine rate allowed isolation of the most catalytically efficient ADA2 variant reported to date. When expressed by human cells, this variant exhibits 30× higher extracellular adenosine degradation activity than the wild-type enzyme. Finally, we demonstrate that Jurkat and CAR T cells engineered to express this secreted, high-activity ADA2 variant can degrade significant amounts of extracellular adenosine in vitro.

Metabonomic analysis of human and 12 kinds of livestock mature milk

Mature milk, as a nutrient-rich endogenous metabolite, has various beneficial effects on the human body. In order to investigate the specific nutrients provided by different dairy products to humans, we used UHPLC-Q-TOF MS to analyze the highly significantly differentially expressed metabolites in 13 species of mammalian mature milk, which were grouped into 17 major metabolite classes with 1992 metabolites based on chemical classification. KEGG shows that 5 pathways in which differentially significant metabolites are actively involved are ABC transporters, Purine metabolism, Pyrimidine metabolism, Phosphotransferase system, Galactose metabolism. The study found that pig milk and goat milk are closer to human milk and contain more nutrients that are beneficial to human health, followed by camel milk and cow milk. In the context of dairy production, the development of goat milk is more likely to meet human needs and health.

Melatonin attenuates diabetes-induced oxidative stress in spleen and suppression of splenocyte proliferation in laboratory mice

Hyperglycaemic condition induced oxidative stress in diabetic individuals caused oxidative damages of internal organs, including immune organ spleen. We studied the effects of low doses of melatonin (25, 50, and 100 µg/100g. B.wt./day) on histoarchitecture, oxidative stress, and splenocyte proliferation in streptozotocin-induced diabetic mice. Melatonin significantly resisted the increase in blood glucose levels and showed a dose-dependent effect on circulatory melatonin, body weight, and relative spleen weight in diabetic mice. Exogenous melatonin suppressed the diabetes-induced lipid peroxidation and increased the activity of the antioxidant enzymes and antioxidant GSH in the spleen tissue of diabetic mice in a dose-dependent manner. Melatonin improved the reactivity of Nrf-2 and HO-1 in the spleen of diabetic mice. Melatonin treatment normalised the splenic cellularity and increased the splenocyte proliferation in a dose-dependent manner. The present study may suggest the dose-dependent effect of melatonin in attenuation of oxidative stress and suppression of splenocyte proliferation in diabetic mice.

Empagliflozin mitigates type 2 diabetes-associated peripheral neuropathy: a glucose-independent effect through AMPK signaling

Diabetic peripheral neuropathy (DPN) represents a severe microvascular condition that dramatically affects diabetic patients despite adequate glycemic control, resulting in high morbidity. Thus, recently, anti-diabetic drugs that possess glucose-independent mechanisms attracted attention. This work aims to explore the potentiality of the selective sodium-glucose cotransporter-2 inhibitor, empagliflozin (EMPA), to ameliorate streptozotocin-induced DPN in rats with insight into its precise signaling mechanism. Rats were allocated into four groups, where control animals received vehicle daily for 2 weeks. In the remaining groups, DPN was elicited by single intraperitoneal injections of freshly prepared streptozotocin and nicotinamide (52.5 and 50 mg/kg, respectively). Then EMPA (3 mg/kg/p.o.) was given to two groups either alone or accompanied with the AMPK inhibitor dorsomorphin (0.2 mg/kg/i.p.). Despite the non-significant anti-hyperglycemic effect, EMPA improved sciatic nerve histopathological alterations, scoring, myelination, nerve fibers’ count, and nerve conduction velocity. Moreover, EMPA alleviated responses to different nociceptive stimuli along with improved motor coordination. EMPA modulated ATP/AMP ratio, upregulated p-AMPK while reducing p-p38 MAPK expression, p-ERK1/2 and consequently p-NF-κB p65 as well as its downstream mediators (TNF-α and IL-1β), besides enhancing SOD activity and lowering MDA content. Moreover, EMPA downregulated mTOR and stimulated ULK1 as well as beclin-1. Likewise, EMPA reduced miR-21 that enhanced RECK, reducing MMP-2 and -9 contents. EMPA’s beneficial effects were almost abolished by dorsomorphin administration. In conclusion, EMPA displayed a protective effect against DPN independently from its anti-hyperglycemic effect, probably via modulating the AMPK pathway to modulate oxidative and inflammatory burden, extracellular matrix remodeling, and autophagy.

Empagliflozin mitigates type 2 diabetes-associated peripheral neuropathy: a glucose-independent effect through AMPK signaling

Diabetic peripheral neuropathy (DPN) represents a severe microvascular condition that dramatically affects diabetic patients despite adequate glycemic control, resulting in high morbidity. Thus, recently, anti-diabetic drugs that possess glucose-independent mechanisms attracted attention. This work aims to explore the potentiality of the selective sodium-glucose cotransporter-2 inhibitor, empagliflozin (EMPA), to ameliorate streptozotocin-induced DPN in rats with insight into its precise signaling mechanism. Rats were allocated into four groups, where control animals received vehicle daily for 2 weeks. In the remaining groups, DPN was elicited by single intraperitoneal injections of freshly prepared streptozotocin and nicotinamide (52.5 and 50 mg/kg, respectively). Then EMPA (3 mg/kg/p.o.) was given to two groups either alone or accompanied with the AMPK inhibitor dorsomorphin (0.2 mg/kg/i.p.). Despite the non-significant anti-hyperglycemic effect, EMPA improved sciatic nerve histopathological alterations, scoring, myelination, nerve fibers' count, and nerve conduction velocity. Moreover, EMPA alleviated responses to different nociceptive stimuli along with improved motor coordination. EMPA modulated ATP/AMP ratio, upregulated p-AMPK while reducing p-p38 MAPK expression, p-ERK1/2 and consequently p-NF-κB p65 as well as its downstream mediators (TNF-α and IL-1β), besides enhancing SOD activity and lowering MDA content. Moreover, EMPA downregulated mTOR and stimulated ULK1 as well as beclin-1. Likewise, EMPA reduced miR-21 that enhanced RECK, reducing MMP-2 and -9 contents. EMPA's beneficial effects were almost abolished by dorsomorphin administration. In conclusion, EMPA displayed a protective effect against DPN independently from its anti-hyperglycemic effect, probably via modulating the AMPK pathway to modulate oxidative and inflammatory burden, extracellular matrix remodeling, and autophagy.

Inosine and its methyl derivatives: Occurrence, biogenesis, and function in RNA

Inosine is one of the most common post-transcriptional modifications. Since its discovery, it has been noted for its ability to contribute to non-Watson-Crick interactions within RNA. Rapidly accumulating evidence points to the widespread generation of inosine through hydrolytic deamination of adenosine to inosine by different classes of adenosine deaminases. Three naturally occurring methyl derivatives of inosine, i.e., 1-methylinosine, 2'-O-methylinosine and 1,2'-O-dimethylinosine are currently reported in RNA modification databases. These modifications are expected to lead to changes in the structure, folding, dynamics, stability and functions of RNA. The importance of the modifications is indicated by the strong conservation of the modifying enzymes across organisms. The structure, binding and catalytic mechanism of the adenosine deaminases have been well-studied, but the underlying mechanism of the catalytic reaction is not very clear yet. Here we extensively review the existing data on the occurrence, biogenesis and functions of inosine and its methyl derivatives in RNA. We also included the structural and thermodynamic aspects of these modifications in our review to provide a detailed and integrated discussion on the consequences of A-to-I editing in RNA and the contribution of different structural and thermodynamic studies in understanding its role in RNA. We also highlight the importance of further studies for a better understanding of the mechanisms of the different classes of deamination reactions. Further investigation of the structural and thermodynamic consequences and functions of these modifications in RNA should provide more useful information about their role in different diseases.

Potential Novel Serum Metabolic Markers Associated With Progression of Prediabetes to Overt Diabetes in a Chinese Population

Background

Identifying the metabolite profile of individuals with prediabetes who turned to type 2 diabetes (T2D) may give novel insights into early T2D interception. The purpose of this study was to identify metabolic markers that predict the development of T2D from prediabetes in a Chinese population.

Methods

We used an untargeted metabolomics approach to investigate the associations between serum metabolites and risk of prediabetes who turned to overt T2D (n=153, mean follow up 5 years) in a Chinese population (REACTION study). Results were compared with matched controls who had prediabetes at baseline [age: 56 ± 7 years old, body mass index (BMI): 24.2 ± 2.8 kg/m2] and at a 5-year follow-up [age: 61 ± 7 years old, BMI: 24.5 ± 3.1 kg/m2]. Confounding factors were adjusted and the associations between metabolites and diabetes risk were evaluated with multivariate logistic regression analysis. A 10-fold cross-validation random forest classification (RFC) model was used to select the optimal metabolites panels for predicting the development of diabetes, and to internally validate the discriminatory capability of the selected metabolites beyond conventional clinical risk factors.

Findings

Metabolic alterations, including those associated with amino acid and lipid metabolism, were associated with an increased risk of prediabetes progressing to diabetes. The most important metabolites were inosine [odds ratio (OR) = 19.00; 95% confidence interval (CI): 4.23-85.37] and carvacrol (OR = 17.63; 95% CI: 4.98-62.34). Thirteen metabolites were found to improve T2D risk prediction beyond eight conventional T2D risk factors [area under the curve (AUC) was 0.98 for risk factors + metabolites vs 0.72 for risk factors, P < 0.05].

Interpretations

Use of the metabolites identified in this study may help determine patients with prediabetes who are at highest risk of progressing to diabetes.

Influence of innate immune activation on endocrine and metabolic pathways in infancy

Prematurity is the leading cause of neonatal morbidity and mortality worldwide. Premature infants often require extended hospital stays, with increased risk of developing infection compared with term infants. A picture is emerging of wide-ranging deleterious consequences resulting from innate immune system activation in the newborn infant. Those who survive infection have been exposed to a stimulus that can impose long-lasting alterations into later life. In this review, we discuss sepsis-driven alterations in integrated neuroendocrine and metabolic pathways and highlight current knowledge gaps in respect of neonatal sepsis. We review established biomarkers for sepsis and extend the discussion to examine emerging findings from human and animal models of neonatal sepsis that propose novel biomarkers for early identification of sepsis. Future research in this area is required to establish a greater understanding of the distinct neonatal signature of early and late-stage infection, to improve diagnosis, curtail inappropriate antibiotic use, and promote precision medicine through a biomarker-guided empirical and adjunctive treatment approach for neonatal sepsis. There is an unmet clinical need to decrease sepsis-induced morbidity in neonates, to limit and prevent adverse consequences in later life and decrease mortality.

Streptozotocin-Induced Diabetic Models in Mice and Rats

Streptozotocin (STZ) is an antibiotic that causes pancreatic islet β-cell destruction and is widely used experimentally to produce a model of type 1 diabetes mellitus (T1DM). Detailed in this article are protocols for producing STZ-induced insulin deficiency and hyperglycemia in mice and rats. Also described are protocols for creating animal models for type 2 diabetes using STZ. These animals are employed for assessing the pathological consequences of diabetes and for screening potential therapies for the treatment of this condition. © 2021 The Authors.

Carvedilol prevents pancreatic β-cell damage and the development of type 1 diabetes in mice by the inhibition of proinflammatory cytokines, NF-κB, COX-2, iNOS and oxidative stress

Inflammation is one of the main mechanisms of pancreatic β-cell damage and the development of type 1 diabetes (T1D). Carvedilol, a beta-adrenergic receptor blocker, has been demonstrated to have anti-inflammatory and antioxidant effects. The aim of this study was to investigate the protective effect of carvedilol against pancreatic β-cell damage and the development of T1D in an experimental model. T1D was induced in mice by multiple low-dose streptozotocin (STZ) injections. Diabetic mice were treated with carvedilol (15 and 20 mg/kg/day, orally) for 14 days. Results showed that blood glucose levels, diabetes incidence, body weight loss and insulitis in the pancreatic tissue were significantly reduced in mice treated with carvedilol. Treatment of mice with carvedilol significantly increased the levels of antioxidants glutathione (GSH), superoxide dismutase (SOD), and catalase and decreased the levels of malondialdehyde (MDA), nitric oxide (NO) and myeloperoxidase (MPO) in the pancreatic tissue as compared with those in the STZ-induced diabetic mice. Carvedilol decreased the expression of nuclear factor kappa B (NF-κB), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) as important modulators of inflammation and β-cell damage in the pancreatic tissue. In addition, carvedilol significantly reduced the levels of proinflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 IL-12, IL-17, interferon (IFN)-γ and chemokine MCP-1, while increased the anti-inflammatory cytokine IL-10 in the pancreatic tissue. In conclusion, these findings suggest that carvedilol is able to prevent pancreatic β-cell damage and the development of T1D in mice by the inhibition of inflammatory and oxidative mediators.

Perturbations of Metabolomic Profiling of Spleen From Rats Infected With Clonorchis sinensis Determined by LC-MS/MS Method

Clonorchiasis is an important zoonotic parasitic disease worldwide. In view of the fact that parasite infection affects host metabolism, and there is an intricate relationship between metabolism and immunity. Metabolic analysis of the spleen could be helpful for understanding the pathophysiological mechanisms in clonorchiasis. A non-targeted ultra high performance liquid tandem chromatography quadrupole time of flight mass spectrometry (UHPLC-QTOF MS) approach was employed to investigate the metabolic profiles of spleen in rats at 4 and 8 weeks post infection with Clonorchis sinensis (C. sinensis). Then a targeted ultra-high performance liquid chromatography multiple reaction monitoring mass spectrometry (UHPLC-MRM-MS/MS) approach was used to further quantify amino acid metabolism. Multivariate data analysis methods, such as principal components analysis and orthogonal partial least squares discriminant analysis, were used to identify differential metabolites. Finally, a total of 396 and 242 significant differential metabolites were identified in ESI+ and ESI− modes, respectively. These metabolites included amino acids, nucleotides, carboxylic acids, lipids and carbohydrates. There were 38 significantly different metabolites shared in the two infected groups compared with the control group through the Venn diagram. The metabolic pathways analysis revealed that pyrimidine metabolism, aminoacyl-tRNA biosynthesis, purine metabolism and phenylalanine, tyrosine and tryptophan biosynthesis were significantly enriched in differential metabolites, which was speculated to be related to the disease progression of clonorchiasis. Furthermore, 15 amino acids screened using untargeted profiling can be accurately quantified and identifed by targeted metabolomics during clonrochiasis. These results preliminarily revealed the perturbations of spleen metabolism in clonorchiasis. Meanwhile, this present study supplied new insights into the molecular mechanisms of host-parasite interactions.

Cardioprotective Effect of Olive Oil Against Ischemia Reperfusion-induced Cardiac Arrhythmia in Isolated Diabetic Rat Heart

Background

Olive oil is rich in monounsaturated fatty acids and has been reported for a variety of beneficial cardiovascular effects, including blood pressure lowering, anti-platelet, anti-diabetic, and anti-inflammatory effects. Diabetes is a major risk factor for cardiac dysfunctions, and olive oil prevents diabetes-induced adverse myocardial remodeling.

Objective

The study aimed to evaluate the effects of olive oil against streptozotocin-induced cardiac dysfunction in animal models of diabetes and ischemia and reperfusion (I/R)-induced cardiac arrhythmias.

Methods

Diabetes was induced in male rats with a single intraperitoneal injection of streptozotocin (60 mg/kg i.p), rats were treated for five, 15, or 56 days with olive oil (1 ml/kg p.o). Control animals received saline. Blood glucose and body weight were monitored every two weeks. At the end of the treatment, rats were sacrificed and hearts were isolated for mounting on Langedorff’s apparatus. The effect of olive oil on oxidative stress and histopathological changes in the cardiac tissues were studied.

Results

The initial blood glucose and body weight were not significantly different in the control and olive-treated animals. Streptozotocin (60 mg/kg i.p) caused a significant increase in the blood glucose of animals as compared to saline-treated animals. The control, saline-treated diabetic animals exhibited a 100% incidence of I/R-induced ventricular fibrillation, which was reduced to 0% with olive oil treatment. The protective effects of olive oil were evident after 15 and 56 days of treatment. Diltiazem, a calcium channel blocker (1 µm/L) showed similar results and protected the I/R-induced cardiac disorders. The cardiac tissues isolated from diabetic rats exhibited marked pathological changes in the cardiomyocytes, including decreased glutathione (GSH) and increased oxidative stress (malondialdehyde; MDA). Pretreatment of animals with olive oil (1 ml/kg p.o) increased GSH and decreased MDA levels. Olive oil also improved the diabetic-induced histopathological changes in the cardiomyocytes.

Conclusion

Olive oil possesses cardiac protective properties against I/R-induced cardiac arrhythmias in rats. It attenuated oxidative stress and diabetes-induced histopathological changes in cardiac tissues. The observed cardiac protectiveness of olive oil in the present investigation may be related to its antioxidant potential.

Enhancement of inosine-mediated A2AR signaling through positive allosteric modulation

Inosine is an endogenous nucleoside that is produced by metabolic deamination of adenosine. Inosine is metabolically more stable (half-life 15h) than adenosine (half-life <10s). Inosine exerts anti-inflammatory and immunomodulatory effects similar to those observed with adenosine. These effects are mediated in part through the adenosine A_2A receptor (A_2AR). Relative to adenosine inosine exhibits a lower affinity towards the A_2AR. Therefore, it is generally believed that inosine is incapable of activating the A_2AR through direct engagement, but indirectly activates the A_2AR upon metabolic conversion to higher affinity adenosine. A handful of studies, however, have provided evidence for direct inosine engagement at the A_2AR leading to activation of downstream signaling events and inhibition of cytokine production. Here, we demonstrate that under conditions devoid of adenosine, inosine as well as an analog of inosine 6-S-[(4-Nitrophenyl)methyl]-6-thioinosine selectively and dose-dependently activated A_2AR-mediated cAMP production and ERK1/2 phosphorylation in CHO cells stably expressing the human A_2AR. Inosine also inhibited LPS-stimulated TNF-α, CCL3 and CCL4 production by splenic monocytes in an A_2AR-dependent manner. In addition, we demonstrate that a positive allosteric modulator (PAM) of the A_2AR enhanced inosine-mediated cAMP production, ERK1/2 phosphorylation and inhibition of pro-inflammatory cytokine and chemokine production. The cumulative effects of allosteric enhancement of adenosine-mediated and inosine-mediated A_2AR activation may be the basis for the sustained anti-inflammatory and immunomodulatory effects observed in vivo and thereby provide insights into potential therapeutic interventions for inflammation- and immune-mediated diseases.

compMS2Miner: An Automatable Metabolite Identification, Visualization, and Data-Sharing R Package for High-Resolution LC-MS Data Sets

A long-standing challenge of untargeted metabolomic profiling by ultrahigh-performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) is efficient transition from unknown mass spectral features to confident metabolite annotations. The compMS2Miner (Comprehensive MS2 Miner) package was developed in the R language to facilitate rapid, comprehensive feature annotation using a peak-picker-output and MS2 data files as inputs. The number of MS2 spectra that can be collected during a metabolomic profiling experiment far outweigh the amount of time required for pain-staking manual interpretation; therefore, a degree of software workflow autonomy is required for broad-scale metabolite annotation. CompMS2Miner integrates many useful tools in a single workflow for metabolite annotation and also provides a means to overview the MS2 data with a Web application GUI compMS2Explorer (Comprehensive MS2 Explorer) that also facilitates data-sharing and transparency. The automatable compMS2Miner workflow consists of the following steps: (i) matching unknown MS1 features to precursor MS2 scans, (ii) filtration of spectral noise (dynamic noise filter), (iii) generation of composite mass spectra by multiple similar spectrum signal summation and redundant/contaminant spectra removal, (iv) interpretation of possible fragment ion substructure using an internal database, (v) annotation of unknowns with chemical and spectral databases with prediction of mammalian biotransformation metabolites, wrapper functions for in silico fragmentation software, nearest neighbor chemical similarity scoring, random forest based retention time prediction, text-mining based false positive removal/true positive ranking, chemical taxonomic prediction and differential evolution based global annotation score optimization, and (vi) network graph visualizations, data curation, and sharing are made possible via the compMS2Explorer application. Metabolite identities and comments can also be recorded using an interactive table within compMS2Explorer. The utility of the package is illustrated with a data set of blood serum samples from 7 diet induced obese (DIO) and 7 nonobese (NO) C57BL/6J mice, which were also treated with an antibiotic (streptomycin) to knockdown the gut microbiota. The results of fully autonomous and objective usage of compMS2Miner are presented here. All automatically annotated spectra output by the workflow are provided in the Supporting Information and can alternatively be explored as publically available compMS2Explorer applications for both positive and negative modes ( https://wmbedmands.shinyapps.io/compMS2_mouseSera_POS and https://wmbedmands.shinyapps.io/compMS2_mouseSera_NEG ). The workflow provided rapid annotation of a diversity of endogenous and gut microbially derived metabolites affected by both diet and antibiotic treatment, which conformed to previously published reports. Composite spectra (n = 173) were autonomously matched to entries of the Massbank of North America (MoNA) spectral repository. These experimental and virtual (lipidBlast) spectra corresponded to 29 common endogenous compound classes (e.g., 51 lysophosphatidylcholines spectra) and were then used to calculate the ranking capability of 7 individual scoring metrics. It was found that an average of the 7 individual scoring metrics provided the most effective weighted average ranking ability of 3 for the MoNA matched spectra in spite of potential risk of false positive annotations emerging from automation. Minor structural differences such as relative carbon-carbon double bond positions were found in several cases to affect the correct rank of the MoNA annotated metabolite. The latest release and an example workflow is available in the package vignette ( https://github.com/WMBEdmands/compMS2Miner ) and a version of the published application is available on the shinyapps.io site ( https://wmbedmands.shinyapps.io/compMS2Example ).

Resetting microbiota by Lactobacillus reuteri inhibits T reg deficiency-induced autoimmunity via adenosine A2A receptors

He et al. show that T reg deficiency markedly induces autoimmunity and shifts gut microbiota. Remodeling microbiota by Lactobacillus reuteri was found to inhibit autoimmunity via the metabolite inosine, which interacts with the adenosine A_2A receptor. This finding establishes a link between the gut microbiota, A_2A receptors, and autoimmunity induced by T reg cell deficiency.

Regulatory T (T reg) cell deficiency causes lethal, CD4⁺ T cell–driven autoimmune diseases. Stem cell transplantation is used to treat these diseases, but this procedure is limited by the availability of a suitable donor. The intestinal microbiota drives host immune homeostasis by regulating the differentiation and expansion of T reg, Th1, and Th2 cells. It is currently unclear if T reg cell deficiency–mediated autoimmune disorders can be treated by targeting the enteric microbiota. Here, we demonstrate that Foxp3⁺ T reg cell deficiency results in gut microbial dysbiosis and autoimmunity over the lifespan of scurfy (SF) mouse. Remodeling microbiota with Lactobacillus reuteri prolonged survival and reduced multiorgan inflammation in SF mice. L. reuteri changed the metabolomic profile disrupted by T reg cell deficiency, and a major effect was to restore levels of the purine metabolite inosine. Feeding inosine itself prolonged life and inhibited multiorgan inflammation by reducing Th1/Th2 cells and their associated cytokines. Mechanistically, the inhibition of inosine on the differentiation of Th1 and Th2 cells in vitro depended on adenosine A_2A receptors, which were also required for the efficacy of inosine and of L. reuteri in vivo. These results reveal that the microbiota–inosine–A_2A receptor axis might represent a potential avenue for combatting autoimmune diseases mediated by T reg cell dysfunction.

Role of NMDA Receptor-Mediated Glutamatergic Signaling in Chronic and Acute Neuropathologies

N-Methyl-D-aspartate receptors (NMDARs) have two opposing roles in the brain. On the one hand, NMDARs control critical events in the formation and development of synaptic organization and synaptic plasticity. On the other hand, the overactivation of NMDARs can promote neuronal death in neuropathological conditions. Ca(2+) influx acts as a primary modulator after NMDAR channel activation. An imbalance in Ca(2+) homeostasis is associated with several neurological diseases including schizophrenia, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. These chronic conditions have a lengthy progression depending on internal and external factors. External factors such as acute episodes of brain damage are associated with an earlier onset of several of these chronic mental conditions. Here, we will review some of the current evidence of how traumatic brain injury can hasten the onset of several neurological conditions, focusing on the role of NMDAR distribution and the functional consequences in calcium homeostasis associated with synaptic dysfunction and neuronal death present in this group of chronic diseases.

Serum metabolic profile predicts adverse central haemodynamics in patients with type 2 diabetes mellitus

AIMS

People with type 2 diabetes mellitus (T2DM) have abnormal peripheral and central haemodynamics at rest and during exercise, probably due to metabolic perturbations, but mechanisms are unknown. We used untargeted metabolomics to determine the relationships between metabolic perturbations and haemodynamics (peripheral and central) measured at rest and during exercise.

METHODS

Serum samples from 39 participants with T2DM (62 ± 9 years; 46 % male) and 39 controls (52 ± 10 years; 51 % male) were analysed by liquid chromatography-mass spectrometry, nuclear magnetic resonance spectroscopy and principal component analysis. Scores on principal components (PC) were used to assess relationships with haemodynamics including peripheral and central BP, central augmentation index (AIx) and central augmentation pressure (AP).

RESULTS

Participants with T2DM had higher resting and exercise haemodynamics (peripheral and central BP, central AIx and central AP) compared to controls (p < 0.05). PC that comprised of a signature metabolic pattern of T2DM was independently associated with resting and exercise central AIx and central AP (p < 0.05).

CONCLUSIONS

Serum metabolic profile was associated with central, but not peripheral, haemodynamics in T2DM participants, suggesting that metabolic irregularities may explain abnormal central haemodynamics in T2DM patients.

The adenosine metabolite inosine is a functional agonist of the adenosine A2A receptor with a unique signaling bias

Inosine is an endogenous purine nucleoside that is produced by catabolism of adenosine. Adenosine has a short half-life (approximately 10s) and is rapidly deaminated to inosine, a stable metabolite with a half-life of approximately 15h. Resembling adenosine, inosine acting through adenosine receptors (ARs) exerts a wide range of anti-inflammatory and immunomodulatory effects in vivo. The immunomodulatory effects of inosine in vivo, at least in part, are mediated via the adenosine A2A receptor (A2AR), an observation that cannot be explained fully by in vitro pharmacological characterization of inosine at the A2AR. It is unclear whether the in vivo effects of inosine are due to inosine or a metabolite of inosine engaging the A2AR. Here, utilizing a combination of label-free, cell-based, and membrane-based functional assays in conjunction with an equilibrium agonist-binding assay we provide evidence for inosine engagement at the A2AR and subsequent activation of downstream signaling events. Inosine-mediated A2AR activation leads to cAMP production with an EC50 of 300.7μM and to extracellular signal-regulated kinase-1 and -2 (ERK1/2) phosphorylation with an EC50 of 89.38μM. Our data demonstrate that inosine produces ERK1/2-biased signaling whereas adenosine produces cAMP-biased signaling at the A2AR, highlighting pharmacological differences between these two agonists. Given the in vivo stability of inosine, our data suggest an additional, previously unrecognized, mechanism that utilizes inosine to functionally amplify and prolong A2AR activation in vivo.

Comparing systemic metabolic responses in mice to single or dual infection with Plasmodium berghei and Heligmosomoides bakeri

Concomitant infections with Plasmodium and gastrointestinal nematodes are frequently observed in humans. At the metabolic level, the cross-talk between the host and multiple coexisting pathogens is poorly characterized. The purpose of this study was to give a comprehensive insight into the systemic metabolic phenotype of mice with a single or dual infection with Plasmodium berghei and Heligmosomoides bakeri. Four groups of eight NMRI female mice were infected with P. berghei or H. bakeri, or with both species concurrently. An additional group remained uninfected, and served as control. Mice were sacrificed at day 19 of the experiment. We collected samples from the liver, spleen, kidney, three intestinal regions, and four brain regions. All biological samples were subjected to (1)H nuclear magnetic resonance spectroscopy, combined with multivariate data analysis, to establish metabolic fingerprints of each tissue from the various infection groups. Compared to uninfected mice, single and dual species infection models showed unique metabolic profiles. P. berghei exerted major effects on glycolysis, tricarboxylic acid cycle, and nucleotide and amino acid metabolism in all studied tissues with the exception of the gut. H. bakeri was characterized by a dysregulation of choline and lipid metabolism in most tissues examined with a particularly strong imprint in the jejunum. Simultaneous co-infection with P. berghei and H. bakeri induced the strongest and most diverse effects in the liver and spleen but led to only minor changes in the intestinal and cerebral parts assessed. Infection with P. berghei showed more pronounced and systemic alterations in the mice metabolic profile than H. bakeri infection. The metabolic fingerprints in the co-infection models were driven by P. berghei infection, whilst the presence of H. bakeri in co-infections had little effect. However, simultaneous co-infection showed indeed the least metabolic disruptions in the peripheral tissues, namely the gut and brain.

DJ-1 Protects Pancreatic Beta Cells from Cytokine- and Streptozotocin-Mediated Cell Death

A hallmark feature of type 1 and type 2 diabetes mellitus is the progressive dysfunction and loss of insulin-producing pancreatic beta cells, and inflammatory cytokines are known to trigger beta cell death. Here we asked whether the anti-oxidant protein DJ-1 encoded by the Parkinson’s disease gene PARK7 protects islet cells from cytokine- and streptozotocin-mediated cell death. Wild type and DJ-1 knockout mice (KO) were treated with multiple low doses of streptozotocin (MLDS) to induce inflammatory beta cell stress and cell death. Subsequently, glucose tolerance tests were performed, and plasma insulin as well as fasting and random blood glucose concentrations were monitored. Mitochondrial morphology and number of insulin granules were quantified in beta cells. Moreover, islet cell damage was determined in vitro after streptozotocin and cytokine treatment of isolated wild type and DJ-1 KO islets using calcein AM/ethidium homodimer-1 staining and TUNEL staining. Compared to wild type mice, DJ-1 KO mice became diabetic following MLDS treatment. Insulin concentrations were substantially reduced, and fasting blood glucose concentrations were significantly higher in MLDS-treated DJ-1 KO mice compared to equally treated wild type mice. Rates of beta cell apoptosis upon MLDS treatment were twofold higher in DJ-1 KO mice compared to wild type mice, and in vitro inflammatory cytokines led to twice as much beta cell death in pancreatic islets from DJ-1 KO mice versus those of wild type mice. In conclusion, this study identified the anti-oxidant protein DJ-1 as being capable of protecting pancreatic islet cells from cell death induced by an inflammatory and cytotoxic setting.

Streptozotocin-Induced Diabetic Models in Mice and Rats

Streptozotocin (STZ) is an antibiotic that produces pancreatic islet β-cell destruction and is widely used experimentally to produce a model of type 1 diabetes mellitus (T1DM). Detailed in this unit are protocols for producing STZ-induced insulin deficiency and hyperglycemia in mice and rats. Also described are protocols for creating animal models for type 2 diabetes using STZ. These animals are employed for assessing the pathological consequences of diabetes and for screening potential therapies for the treatment of this condition.

Genistein modulation of streptozotocin diabetes in male B6C3F1 mice can be induced by diet

Diet and phytoestrogens affect the development and progression of diabetes. The objective of the present study was to determine if oral exposure to phytoestrogen genistein (GE) by gavage changed blood glucose levels (BGL) through immunomodulation in streptozotocin (STZ)-induced diabetic male B6C3F1 mice fed with three different diets. These three diets were: NTP-2000 diet (NTP), soy- and alfalfa-free 5K96 diet (SOF) and high fat diet (HFD) with 60% of kcal from fat, primarily rendered fat of swine. The dosing regimen for STZ consisted of three 100mg/kg doses (i.p.): the first dose was administered at approximately 2weeks following the initiation of daily GE (20mg/kg) gavage, and the second dose was on day 19 following the first dose, and the third dose was on day 57 following the first dose. In mice on the NTP diet, GE treatment decreased BGL with statistical significances observed on days 33 and 82 following the first STZ injection. In mice fed the HFD diet, GE treatment produced a significant decrease and a significant increase in BGL on days 15 and 89 following the first STZ injection, respectively. In mice fed the SOF diet, GE treatment had no significant effects on BGL. Although GE treatment affected phenotypic distributions of both splenocytes (T cells, B cells, natural killer cells and neutrophils) and thymocytes (CD4/CD8 and CD44/CD25), and their mitochondrial transmembrane potential and generation of reactive oxygen species, indicators of cell death (possibly apoptosis), GE modulation of neutrophils was more consistent with its diabetogenic or anti-diabetic potentials. The differential effects of GE on BGL in male B6C3F1 mice fed with three different diets with varied phytoestrogen contents suggest that the estrogenic properties of this compound may contribute to its modulation of diabetes.

Effect of ginseng polysaccharide on the urinary excretion of type 2 diabetic rats studied by liquid chromatography-mass spectrometry

Ginseng polysaccharide is known to have anti-hyperglycemic and anti-hyperlipidemic effects in vivo and its precise mechanism of action is not clear. A urinary metabolomics method based on rapid-resolution liquid chromatography/mass spectrometry (RRLC/MS) was developed to investigate the effect of water-soluble ginseng polysaccharide (WGP) on type 2 diabetes in rats. Principal component analysis (PCA) was carried out for pattern recognition and a clear separation between type 2 diabetic rats and those treated with WGP was achieved. Eight potential biomarkers were found and identified. Significantly increased inosine, serotonin, phenylpropionylglycine and dodecanedioic acid showed the effect of WGP on purine metabolism, tryptophan metabolism, fatty acid metabolism and energy metabolism. 1-Methyladenine, 4-deoxyerythronic acid, 5-hydroxyhexanoic acid and tetrahydrocortisol were significantly decreased which indicated that WGP can regulate DNA metabolism, organic acids metabolism and steroid hormone metabolism. This work is helpful in the effect mechanism study of ginseng polysaccharide.

Streptozotocin-induced diabetic models in mice and rats

Streptozotocin (STZ) is an antibiotic that can cause pancreatic β-cell destruction, so it is widely used experimentally as an agent capable of inducing insulin-dependent diabetes mellitus (IDDM), also known as type 1 diabetes mellitus (T1DM). This unit describes protocols for the production of insulin deficiency and hyperglycemia in mice and rats, using STZ. These models for diabetes can be employed for assessing the mechanisms of T1DM, screening potential therapies for the treatment of this condition, and evaluation of therapeutic options.

Interleukin (IL)-10 induced by CD11b(+) cells and IL-10-activated regulatory T cells play a role in immune modulation of mesenchymal stem cells in rat islet allografts

Mesenchymal stem cells (MSCs) are suggested to be immune modulators because of their therapeutic potential in transplantation. In the present study, we evaluated the therapeutic potential of autologous MSCs for preventing graft rejection after allogeneic rat islet transplantation. We assessed the ability of MSCs to elicit an antiproliferative response in alloreactive lymphocytes and tested the immunosuppressive effect of MSCs in allogeneic islet transplantation. In islet allotransplantation, injection of autologous MSCs or a subtherapeutic dose of cyclosporine A (CsA; 5 mg/kg) alone did not prolong allograft survival. However, graft survival was attained for >100 d in 33% of autologous MSC-plus-CsA-treated recipients, indicating that graft acceptance was achieved in a subgroup of allograft recipients. Splenocytes from autologous MSC-plus-CsA-treated rats exhibited a reduced mixed lymphocyte reaction (MLR)-proliferative response to donor stimulators and increased interleukin (IL)-10 release. Interestingly, after excluding host CD11b(+) cells, splenic T cells from autologous MSC-plus-CsA-treated rats did not produce IL-10 or did not inhibit proliferative responses under the same conditions. The use of autologous MSC-plus-CsA downregulated immune responses, inducing donor-specific T-cell hyporesponsiveness by reducing the production of proinflammatory cytokines and inducing antiinflammatory cytokine production, especially that of IL-10, during the early posttransplantation period. T-regulatory cells made a contribution at a later phase. In conclusion, the combined use of autologous MSCs and low-dose CsA exerted a synergistic immunosuppressive effect in an islet allograft model, suggesting a role for autologous MSCs as an immune modulator.

Systems parasitology: effects of Fasciola hepatica on the neurochemical profile in the rat brain

We characterize the integrated response of a rat host to the liver fluke Fasciola hepatica using a combination of ¹H nuclear magnetic resonance spectroscopic profiles (liver, kidney, intestine, brain, spleen, plasma, urine, feces) and multiplex cytokine markers of systemic inflammation. Multivariate mathematical models were built to describe the main features of the infection at the systems level. In addition to the expected modulation of hepatic choline and energy metabolism, we found significant perturbations of the nucleotide balance in the brain, together with increased plasma IL-13, suggesting a shift toward modulation of immune reactions to minimize inflammatory damage, which may favor the co-existence of the parasite in the host. Subsequent analysis of brain extracts from other trematode infection models (i.e. Schistosoma mansoni, and Echinostoma caproni) did not elicit a change in neural nucleotide levels, indicating that the neural effects of F. hepatica infection are specific. We propose that the topographically extended response to invasion of the host as characterized by the modulated global metabolic phenotype is stratified across several bio-organizational levels and reflects the direct manipulation of host–nucleotide balance.

Adenosine A2A receptors and uric acid mediate protective effects of inosine against TNBS-induced colitis in rats

Inflammatory bowel disease comprises chronic recurrent inflammation of gastrointestinal tract. This study was conducted to investigate inosine, a potent immunomodulator, in 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced chronic model of experimental colitis, and contribution of adenosine A(2A) receptors and the metabolite uric acid as possible underlying mechanisms. Experimental colitis was rendered in rats by a single colonic administration of 10 mg of TNBS. Inosine, potassium oxonate (a hepatic uricase inhibitor), SCH-442416 (a selective adenosine A(2A) receptor antagonist), inosine+potassium oxonate, or inosine+SCH-442416 were given twice daily for 7 successive days. At the end of experiment, macroscopic and histopathologic scores, colonic malondialdehyde (MDA), Tumor Necrosis Factor-alpha (TNF-α) and Interleukin-1beta (IL-1β) levels, and myeloperoxidase (MPO) activity were assessed. Plasma uric acid level was measured throughout the experiment. Both macroscopic and histological features of colonic injury were markedly ameliorated by either inosine, oxonate or inosine+oxonate. Likewise, the elevated amounts of MPO and MDA abated as well as those of TNF-α and IL-1β (P<0.05). SCH-442416 partially reversed the effect of inosine on theses markers, while inosine+oxonate showed a higher degree of protection than each treatment alone (P<.0.05). No significant difference was observed between TNBS and SCH-442416 groups. Uric acid levels were significantly higher in inosine or oxonate groups compared to control. Inosine+oxonate resulted in an even more elvelated uric acid level than each treatment alone (P<0.05). Inosine elicits notable anti-inflammatory effects on TNBS-induced colitis in rats. Uric acid and adenosine A(2A) receptors contribute to these salutary properties.

The novel inosine analogue INO-2002 exerts an anti-inflammatory effect in a murine model of acute lung injury

Endogenous purines, including inosine, have been shown to exert immunomodulatory and anti-inflammatory effects in a variety of disease models. The dosage of inosine required for these effects has been shown to be between 200 and 600 mg kg(-1) because of the rapid metabolism of inosine in vivo. The aim of this study was to determine whether a metabolic resistant purine analog, INO-2002, exerts anti-inflammatory effects in an animal model of acute respiratory distress syndrome. Mice challenged with intratracheal LPS (50 microg) were treated with INO-2002 (30 or 100 mg kg(-1), i.p.) in divided doses at either 1 and 12 h or at 5 and 16 h. After 24 h, bronchoalveolar lavage fluid was obtained to measure leukocyte infiltration by myeloperoxidase levels, lung edema by protein levels, and proinflammatory chemokine (macrophage inflammatory protein 1alpha) and cytokine (TNF-alpha, IL-1, and IL-6) levels. INO-2002 (30 and 100 mg kg(-1)) reduced the LPS-mediated infiltration of leukocytes and edema as evidenced by bronchoalveolar lavage fluid reduction in levels of myeloperoxidase and protein. INO-2002 also downregulated expression of the proinflammatory mediators macrophage inflammatory protein 1alpha, TNF-alpha, IL-1, and IL-6. Delaying the start of treatment by 5 h after LPS administration affected the potency of INO-2002 protective effects, with 100 but not 30 mg kg(-1) having anti-inflammatory effects. The inosine analog INO-2002 largely suppressed LPS-induced inflammation in vivo at doses lower than those needed for the naturally occurring purine inosine. These data support the proposal that purine analogs, resistant to metabolic breakdown, may represent a useful addition to the therapy of acute respiratory distress syndrome.

Adenosine: an endogenous modulator of innate immune system with therapeutic potential

Adenosine is a purine nucleoside, which is produced inside the body under metabolic stress like hypoxic conditions, acute or chronic inflammatory tissue insults. The synthesis of adenosine involves the catabolism of adenine nucleotides (ATP, ADP and AMP) by the action of extracellular ectonucleotidases i.e. CD39 or nucleoside triphosphate dephosphorylase (NTPD) and CD73 or 5'-ectonucleotidase. Once adenosine is released in the extracellular environment, it binds to different types of adenosine (i.e. adenosine A(1), A(2A), A(2B) and A(3) receptors) receptors expressed on various innate immune cells [Neutrophils, macrophages, mast cells, dendritic cells and natural killer cells]. Thus, depending on the type of adenosine receptor to which it binds, adenosine modulates innate immune response during various inflammatory conditions [i.e. chronic (cancer, asthma) as well as acute (sepsis, acute lung injury) inflammatory diseases]. This review summarizes the effect of adenosine on innate immunity and the use of adenosine receptor specific agonists or antagonists in various immunologic disorders (asthma, cancer, HIV-1 infection) as future immunomodulatory therapeutics.

The novel inosine analogue, INO-2002, protects against diabetes development in multiple low-dose streptozotocin and non-obese diabetic mouse models of type I diabetes

Endogenous purines including inosine have been shown to exert immunomodulatory and anti-inflammatory effects in a variety of disease models. The dosage of inosine required for protection is very high because of the rapid metabolism of inosine in vivo. The aim of this study was to determine whether a metabolic-resistant purine analogue, INO-2002, exerts anti-inflammatory effects in two animal models of type I diabetes. Type I diabetes was induced chemically with streptozotocin or genetically using the non-obese diabetic (NOD) female mouse model. Mice were treated with INO-2002 or inosine as required at 30, 100, or 200 mg/kg per day, while blood glucose and diabetes incidence were monitored. The effect of INO-2002 on the pancreatic cytokine profile was also determined. INO-2002 reduced both the hyperglycaemia and incidence of diabetes in both streptozotocin-induced and spontaneous diabetes in NOD mice. INO-2002 proved to be more effective in protecting against diabetes than the naturally occurring purine, inosine, when administered at the same dose. INO-2002 treatment decreased pancreatic levels of interleukin (IL)-12 and tumour necrosis factor-alpha, while increasing levels of IL-4 and IL-10. INO-2002 also reduced pancreatic levels of the chemokine MIP-1 alpha. The inosine analogue, INO-2002, was protected more effectively than the naturally occurring purine, inosine, against development of diabetes in two separate animal models. INO-2002 exerts protective effects by changing the pancreatic cytokine expression from a destructive Th1 to a protective Th2 profile. The use of analogues of inosine such as INO-2002 should be considered as a potential preventative therapy in individuals susceptible to developing type I diabetes.

Novel role of curcumin in the prevention of cytokine-induced islet death in vitro and diabetogenesis in vivo

BACKGROUND AND PURPOSE

Oxidative stress caused by cytokine exposure is a major cause of pancreatic islet death in vitro and of diabetogenesis. Antioxidant compounds may prevent cytokine-induced damage to islet cells. Hence, we studied the potential of curcumin, an antioxidant and anti-inflammatory compound, in vitro to protect islets against pro-inflammatory cytokines and in vivo to prevent the progression of diabetes induced by multiple low doses of streptozotocin (MLD-STZ).

EXPERIMENTAL APPROACH

Pancreatic islets from C57/BL6J mice were pretreated with curcumin (10 microM) and then exposed to a combination of cytokines. Islet viability, reactive oxygen species (ROS), NO, inducible NO synthase and NF-kappaB translocation were studied. Curcumin pretreated (7.5 mg kg(-1) day(-1)) C57/BL6J mice were given MLD-STZ (40 mg kg(-1)), and various parameters of diabetes induction and progression were monitored.

KEY RESULTS

Curcumin protected islets from cytokine-induced islet death in vitro by scavenging ROS and normalized cytokine-induced NF-kappaB translocation by inhibiting phosphorylation of inhibitor of kappa B alpha (IkappaBalpha). In vivo, curcumin also prevented MLD-STZ, as revealed by sustained normoglycaemia, normal glucose clearance and maintained pancreatic GLUT2 levels. Pro-inflammatory cytokine concentrations in the serum and pancreas were raised in STZ-treated animals, but not in animals pretreated with curcumin before STZ.

CONCLUSIONS AND IMPLICATIONS

Here, we have demonstrated for the first time that curcumin in vitro protects pancreatic islets against cytokine-induced death and dysfunction and in vivo prevents STZ-induced diabetes.

Methadone ameliorates multiple-low-dose streptozotocin-induced type 1 diabetes in mice

Type 1 diabetes is an autoimmune disease characterized by inflammation of pancreatic islets and destruction of beta cells by the immune system. Opioids have been shown to modulate a number of immune functions, including T helper 1 (Th1) and T helper 2 (Th2) cytokines. The immunosuppressive effect of long-term administration of opioids has been demonstrated both in animal models and humans. The aim of this study was to determine the effect of methadone, a mu-opioid receptor agonist, on type 1 diabetes. Administration of multiple low doses of streptozotocin (STZ) (MLDS) (40 mg/kg intraperitoneally for 5 consecutive days) to mice resulted in autoimmune diabetes. Mice were treated with methadone (10 mg/kg/day subcutaneously) for 24 days. Blood glucose, insulin and pancreatic cytokine levels were measured. Chronic methadone treatment significantly reduced hyperglycemia and incidence of diabetes, and restored pancreatic insulin secretion in the MLDS model. The protective effect of methadone can be overcome by pretreatment with naltrexone, an opioid receptor antagonist. Also, methadone treatment decreased the proinflammatory Th1 cytokines [interleukin (IL)-1beta, tumor necrosis factor-alpha and interferon-gamma] and increased anti-inflammatory Th2 cytokines (IL-4 and IL-10). Histopathological observations indicated that STZ-mediated destruction of beta cells was attenuated by methadone treatment. It seems that methadone as an opioid agonist may have a protective effect against destruction of beta cells and insulitis in the MLDS model of type 1 diabetes.

Adenosine receptor activation ameliorates type 1 diabetes

Growing evidence indicates that adenosine receptors could be promising therapeutic targets in autoimmune diseases. Here we studied the role of adenosine receptors in controlling the course of type 1 diabetes. Diabetes in CD-1 mice was induced by multiple-low-dose-streptozotocin (MLDS) treatment and in nonobese diabetic (NOD) mice by cyclophosphamide injection. The nonselective adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA) prevented diabetes development in both MLDS-challenged mice and in cyclophosphamide-treated NOD mice. The effect of NECA was reversed by the selective A2B receptor antagonist N-(4-cyanophenyl)-2-[4-(2,3,6,7-tetrahydro-2,6-dioxo-1,3-dipropyl-1H-purin-8-yl)phenoxy]acetamide (MRS 1754). The selective A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA) and A3 receptor agonist N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (IB-MECA) were less efficacious in ameliorating the course of diabetes. NECA inhibited diabetes in A2A receptor KO mice and the selective A2A receptor agonist 2-p-(2-carboxyethyl)phenethyl-amino-5'-N-ethyl-carboxamidoadenosine (CGS21680) had no effect in normal mice, indicating a lack of role of A2A receptors. NECA failed to prevent cytokine-induced beta-cell death in vitro, but NECA strongly suppressed expression of the proinflammatory cytokines TNF-alpha, MIP-1alpha, IL-12, and IFN-gamma in pancreata, endotoxin, or anti-CD3-stimulated splenic cells, and T helper 1 lymphocytes, indicating that the beneficial effect of NECA was due to immunomodulation. These results demonstrate that adenosine receptor ligands are potential candidates for the treatment of type 1 diabetes.

Immunomodulatory effect of the purine nucleoside inosine following spinal cord contusion injury in rat

STUDY DESIGN

In vivo study using a moderate spinal cord contusion injury (SCI) model in adult rat.

OBJECTIVE

To assess the immunomodulatory effects of the purine nucleoside inosine on macrophage/microglia activation at and near the lesion site and in white matter areas remote from the injury epicenter.

SETTING

Department of Cell and Developmental Biology, SUNY Upstate Medical University, Syracuse, NY, USA.

METHODS

Animals (N=56) were injured using a moderate SCI at T9-T10 spinal level and were divided into three groups, depending on treatment paradigm. Rats received either intraperitoneal or subcutaneous injections of inosine (N=28) or vehicle (N=28). Spinal cord tissue was processed for ED-1 immunoreactivity and the volume fraction of ED-1(+) profiles was calculated using the Cavalieri method and unbiased stereology.

RESULTS

The volume fraction of ED-1(+) profiles within gray and lateral white matter regions at and around the lesion site was significantly reduced only following a twice daily-6 week treatment course, compared with vehicle controls, and white matter areas remote from the lesion were unaffected by all inosine treatment paradigms.

CONCLUSIONS

Continued subcutaneous delivery of inosine, beginning 15-min post-SCI and persisting throughout the survival period of 6 weeks exerted immunomodulatory effects at and around the lesion site.

Protective effects of inosine on mice subjected to lethal total-body ionizing irradiation

Mammals can barely survive total-body ionizing irradiation greater than 10 Gy. To date, there are few drugs available for radioprotective therapy under such circumstances. Inosine, a natural derivative of adenosine, has been known to provide powerful protection for many kinds of cells and tissues against various insults both in vitro and in vivo. In the present study, we examined whether inosine was also beneficial for mammals subjected to an absolutely lethal total-body ionizing irradiation. Immediately after adult Balb/c mice were exposed to (60)Co gamma-rays at a single dose of 12 Gy, a moiety of them were administered daily with inosine or adenosine, either at doses of 375 or 750 micromol/kg up to death, and their body weight and survival time were recorded. Some irradiated mice were administered inosine or adenosine daily at doses of 750 micromol/kg and assessed for spatial memory abilities using the Morris water maze. The results demonstrated that, although inosine could not prevent body weight loss in irradiated mice, it was able to significantly prolong their survival time at doses of 750 micromol/kg. Moreover, inosine but not adenosine could suppress spatial memory deficit in irradiated mice. The data suggested that inosine had protective effects on mammals suffering from total-body ionizing irradiation at a single lethal dose.

The purine metabolism of human erythrocytes

This review summarizes currently available information about a crucial part of erythrocyte metabolism, that is, purine nucleotide conversions and their relationships with other conversion pathways. We describe the cellular resynthesis, interconversion, and degradation of purine compounds, and also the regulatory mechanisms in the conversion pathways. We also mention purine metabolism disorders and their clinical consequences. The literature is fragmentary because studies have concentrated only on selected aspects of purine metabolism; hence the need for a synthetic approach.

Adenosine is a negative regulator of NF-κB and MAPK signaling in human intestinal epithelial cells

Previous studies suggest that adenosine possesses anti-inflammatory properties, however, the mechanisms by which adenosine affects immune function remain unclear, particularly in the intestine. In this study, we hypothesized that adenosine directly affects pro-inflammatory gene expression in intestinal epithelial cells through modulation of NF-kappaB signaling. HT-29 cells were treated with adenosine prior to incubation with various stimuli and pro-inflammatory gene expression and signal transduction analyzed. Adenosine pretreatment resulted in a reduction in IL-8 expression and secretion in response to TNF-alpha, IL-1, LPS, and PMA. This effect was paralleled by inhibition of kappaB-driven luciferase expression and a reduction in recruitment of NF-kappaB to the IL-8 promoter. Pretreatment of HT-29 cells also resulted in reduced ERK, p38, and JNK MAPK phosphorylation, following TNF-alpha treatment. The observed effects in this study occurred independently of known surface adenosine receptors. This study identifies adenosine as a potent negative regulator of pro-inflammatory signaling in intestinal epithelial cells.