Purines inhibit poly(ADP-ribose) polymerase activation and modulate oxidant-induced cell death

Targeting NAD Metabolism for the Therapy of Age-Related Neurodegenerative Diseases

As the aging population continues to grow rapidly, age-related diseases are becoming an increasing burden on the healthcare system and a major concern for the well-being of elderly individuals. While aging is an inevitable process for all humans, it can be slowed down and age-related diseases can be treated or alleviated. Nicotinamide adenine dinucleotide (NAD) is a critical coenzyme or cofactor that plays a central role in metabolism and is involved in various cellular processes including the maintenance of metabolic homeostasis, post-translational protein modifications, DNA repair, and immune responses. As individuals age, their NAD levels decline, and this decrease has been suggested to be a contributing factor to the development of numerous age-related diseases, such as cancer, diabetes, cardiovascular diseases, and neurodegenerative diseases. In pursuit of healthy aging, researchers have investigated approaches to boost or maintain NAD levels. Here, we provide an overview of NAD metabolism and the role of NAD in age-related diseases and summarize recent progress in the development of strategies that target NAD metabolism for the treatment of age-related diseases, particularly neurodegenerative diseases.

Integrated omics analysis unveils a DNA damage response to neurogenic injury

Spinal cord injury (SCI) evokes profound bladder dysfunction. Current treatments are limited by a lack of molecular data to inform novel therapeutic avenues. Previously, we showed systemic inosine treatment improved bladder function following SCI in rats. Here, we applied multi-omics analysis to explore molecular alterations in the bladder and their sensitivity to inosine following SCI. Canonical pathways regulated by SCI included those associated with protein synthesis, neuroplasticity, wound healing, and neurotransmitter degradation. Upstream regulator analysis identified MYC as a key regulator, whereas causal network analysis predicted multiple regulators of DNA damage response signaling following injury, including PARP-1. Staining for both DNA damage (γH2AX) and PARP activity (poly-ADP-ribose) markers in the bladder was increased following SCI, and attenuated in inosine-treated tissues. Proteomics analysis suggested that SCI induced changes in protein synthesis-, neuroplasticity-, and oxidative stress-associated pathways, a subset of which were shown in transcriptomics data to be inosine-sensitive. These findings provide novel insights into the molecular landscape of the bladder following SCI, and highlight a potential role for PARP inhibition to treat neurogenic bladder dysfunction.

Association of Metabolites, Nutrients, and Toxins in Maternal and Cord Serum with Asthma, IgE, SPT, FeNO, and Lung Function in Offspring

The role of metabolites, nutrients, and toxins (MNTs) in sera at the end of pregnancy and of their association with offspring respiratory and allergic disorders is underexplored. Untargeted approaches detecting a variety of compounds, known and unknown, are limited. In this cohort study, we first aimed at discovering associations of MNTs in grandmaternal (F0) serum with asthma, immunoglobulin E, skin prick tests, exhaled nitric oxide, and lung function parameters in their parental (F1) offspring. Second, for replication, we tested the identified associations of MNTs with disorders in their grandchildren (F2-offspring) based on F2 cord serum. The statistical analyses were sex-stratified. Using liquid chromatography/high-resolution mass spectrometry in F0, we detected signals for 2286 negative-ion lipids, 59 positive-ion lipids, and 6331 polar MNTs. Nine MNTs (one unknown MNT) discovered in F0-F1 and replicated in F2 showed higher risks of respiratory/allergic outcomes. Twelve MNTs (four unknowns) constituted a potential protection in F1 and F2. We recognized MNTs not yet considered candidates for respiratory/allergic outcomes: a phthalate plasticizer, an antihistamine, a bile acid metabolite, tryptophan metabolites, a hemiterpenoid glycoside, triacylglycerols, hypoxanthine, and polyphenol syringic acid. The findings suggest that MNTs are aspirants for clinical trials to prevent adverse respiratory/allergic outcomes.

Natural Guanine Derivatives Exert PARP-Inhibitory and Cytoprotective Effects in a Model of Cardiomyocyte Damage under Oxidative Stress

Inhibitors of human poly(ADP-ribose) polymerase (PARP) are considered as promising agents for treatment of cardiovascular, neurological, and other diseases accompanied by inflammation and oxidative stress. Previously, the ability of natural compounds 7-methylguanine (7mGua) and 8-hydroxy-7-methylguanine (8h7mGua) to suppress activity of the recombinant PARP protein was demonstrated. In the present work, we have investigated the possibility of PARP-inhibitory and cytoprotective action of 7mGua and 8h7mGua against the rat cardiomyoblast cultures (undifferentiated and differentiated H9c2). It was found that 7mGua and 8h7mGua rapidly penetrate into the cells and effectively suppress the H2O2-stimulated PARP activation (IC50 = 270 and 55 μM, respectively). The pronounced cytoprotective effects of 7mGua and 8h7mGua were shown in a cellular model of oxidative stress, and effectiveness of 8h7mGua exceeded the classic PARP inhibitor 3-aminobenzamide. The obtained data indicate promise for the development of PARP inhibitors based on guanine derivatives and their testing using the models of ischemia-reperfusion tissue damage.

Using follicular fluid metabolomics to investigate the association between air pollution and oocyte quality

BACKGROUND AND AIM

Our objective was to use metabolomics in a toxicological-relevant target tissue to gain insight into the biological processes that may underlie the negative association between air pollution exposure and oocyte quality.

METHODS

Our study included 125 women undergoing in vitro fertilization at an academic fertility center in Massachusetts, US (2005-2015). A follicular fluid sample was collected during oocyte retrieval and untargeted metabolic profiling was conducted using liquid chromatography with ultra-high-resolution mass spectrometry and two chromatography columns (C18 and HILIC). Daily exposure to nitrogen dioxide (NO2), ozone, fine particulate matter, and black carbon was estimated at the women's residence using spatiotemporal models and averaged over the period of ovarian stimulation (2-weeks). Multivariable linear regression models were used to evaluate the associations between the air pollutants, number of mature oocytes, and metabolic feature intensities. A meet-in-the-middle approach was used to identify overlapping features and metabolic pathways.

RESULTS

Of the air pollutants, NO2 exposure had the largest number of overlapping metabolites (C18: 105; HILIC: 91) and biological pathways (C18: 3; HILIC: 6) with number of mature oocytes. Key pathways of overlap included vitamin D3 metabolism (both columns), bile acid biosynthesis (both columns), C21-steroid hormone metabolism (HILIC), androgen and estrogen metabolism (HILIC), vitamin A metabolism (HILIC), carnitine shuttle (HILIC), and prostaglandin formation (C18). Three overlapping metabolites were confirmed with level-1 or level-2 evidence. For example, hypoxanthine, a metabolite that protects against oxidant-induced cell injury, was positively associated with NO2 exposure and negatively associated with number of mature oocytes. Minimal overlap was observed between the other pollutants and the number of mature oocytes.

CONCLUSIONS

Higher exposure to NO2 during ovarian stimulation was associated with many metabolites and biologic pathways involved in endogenous vitamin metabolism, hormone synthesis, and oxidative stress that may mediate the observed associations with lower oocyte quality.

Multi-omics analysis to characterize molecular adaptation of Entamoeba histolytica during serum stress

Entamoeba histolytica is responsible for dysentery and extraintestinal disease in humans. To establish successful infection, it must generate adaptive response against stress due to host defense mechanisms. We have developed a robust proteomics workflow by combining miniaturized sample preparation, low flow-rate chromatography, and ultra-high sensitivity mass spectrometry, achieving increased proteome coverage, and further integrated proteomics and RNA-seq data to decipher regulation at translational and transcriptional levels. Label-free quantitative proteomics led to identification of 2344 proteins, an improvement over the maximum number identified in E. histolytica proteomic studies. In serum-starved cells, 127 proteins were differentially abundant and were associated with functions including antioxidant activity, cytoskeleton, translation, catalysis, and transport. The virulence factor, Gal/GalNAc-inhibitable lectin subunits, was significantly altered. Integration of transcriptomic and proteomic data revealed that only 30% genes were coordinately regulated at both transcriptional and translational levels. Some highly expressed transcripts did not change in protein abundance. Conversely, genes with no transcriptional change showed enhanced protein abundance, indicating post-transcriptional regulation. This multi-omics approach enables more refined gene expression analysis to understand the adaptive response of E. histolytica during growth stress.

Aqueous Extracts of Fish Roe as a Source of Several Bioactive Compounds

Regular consumption of seafood and, in particular, fish has been associated with important health benefits. A fish product that has been increasingly included in the human nutrition is roe. Despite its nutritional value has been established (fatty acid profile and protein content), the knowledge of the composition of its aqueous extracts is still limited. This work describes the bioactive compounds profile in the roe-derived aqueous extracts of three different marine species (sardine, horse mackerel and sea bass) using a method based on liquid chromatography coupled to high-resolution mass spectrometry with an electrospray ionisation source (LC-ESI/HRMS). The presence of substances with well-known nutritional and functional properties (e.g., antioxidant and anti-inflammatory properties) was demonstrated, namely essential amino acids (e.g., taurine), peptides (e.g., anserine and carnosine), B-group vitamins (e.g., nicotinamide) and gadusol. Therefore, roe-derived aqueous extracts are excellent sources of bioactive compounds and may be used as a font of functional components for several medical and veterinary applications.

The use of non-targeted metabolomics to assess the toxicity of bifenthrin to juvenile Chinook salmon (Oncorhynchus tshawytscha)

An increase in urban and agricultural application of pyrethroid insecticides in the San Francisco Bay Estuary and Sacramento San Joaquin Delta has raised concern for the populations of several salmonids, including Chinook salmon (Oncorhynchus tshawytscha). Bifenthrin, a type I pyrethroid, is among the most frequently detected pyrethroids in the Bay-Delta watershed, with surface water concentrations often exceeding chronic toxicity thresholds for several invertebrate and fish species. To better understand the mechanisms of bifenthrin-induced neurotoxicity, juvenile Chinook salmon were exposed to concentrations of bifenthrin previously measured in the Delta. Non-targeted metabolomic profiles were used to identify transcriptomic changes in the brains of bifenthrin-exposed fish. Pathway analysis software predicted increased apoptotic, inflammatory, and reactive oxygen species (ROS) responses in Chinook following exposure to 0.15 and 1.50 μg/L bifenthrin for 96 h. These responses were largely driven by reduced levels of inosine, hypoxanthine, and guanosine. Subsequently, in the brain, the expression of caspase 3, a predominant effector for apoptosis, was significantly upregulated following exposure to 1.50 μg/L bifenthrin. This data suggests that metabolites involved in inflammatory and apoptotic responses, as well as those involved in maintaining proper neuronal function may be disrupted following sublethal exposure to bifenthrin and further suggests that additional population studies should focus on behavioral responses associated with impaired brain function.

Therapeutic effect of adenosine on experimentally induced acute ulcerative colitis model in rats

Purpose

To examine the therapeutic effect of external adenosine on an acetic acid-induced acute ulcerative colitis model in rats.

Methods

Thirty male mature rats were divided into three groups as control, acute colitis (AC) and AC+adenosine group (AC+AD). AC was induced by rectal administration of 4% acetic acid (AA). 5mg/kg/day adenosine was performed i.p for 4 weeks to AC+AD group. Rectum and colon were excised for microscopic and histopathological histopathologic evaluations, and immunohistochemical analysis of nuclear factor kappa B (NF-kB). Blood samples were collected for biochemical detection of TNF-α, Pentraxin-3 and malondialdehyde (MDA) levels.

Results

AC group had generalized hyperemia and hemorrhage with increased macroscopic and histopathological scores compared with control (P <0.0001) while adenosine treatment decreased these scores significantly (P <0.001), with reduced distribution of disrupted epithelium, leukocyte infiltrates, and focal hemorrhage. AC group showed significantly increased immunoexpression of NF-kB in rectum, plasma and tissue levels of TNF-α, plasma Pentraxin-3 and MDA levels (P <0.0001) while adenosine reduced these levels (P < 0.05).

Conclusion

Adenosine appears to promote healing of colon and rectum exposed to AA-induced AC, suggesting a boosting effect of adenosine on the intestinal immune system to cure ulcerative colitis.

Fanconi Anemia complementation group C protein in metabolic disorders

Given importance of 22-Fanconi Anemia (FA) proteins together to act in a signaling pathway in preventing deleterious clinical symptoms, e.g. severe bone marrow failure, congenital defects, an early onset of aging and cancer, studies on each FA protein become increasingly attractive. However, an unbiased and systematic investigation of cellular effects resulting from each FA protein is missing. Here, we report roles of FA complementation C group protein (FANCC) in the protection from metabolic disorders. This study was prompted by the diabetes-prone feature displayed in FANCC knockout mice, which is not typically shown in patients with FA. We found that in cells expressing FANCC at different levels, there are representative alterations in metabolites associated with aging (glycine, citrulline, ornithine, L-asparagine, L-tyrosine, L-arginine, L-glutamine, L-leucine, L-isoleucine, L-valine, L-proline and L-alanine), Diabetes Mellitus (DM) (carbon monoxide, collagens, fatty acids, D-glucose, fumaric acid, 2-oxoglutaric acid, C3), inflammation (inosine, L-arginine, L-isoleucine, L-leucine, L-lysine, L-phenylalanine, hypoxanthine, L-methionine), and cancer ( L-methionine, sphingomyelin, acetyl-L-carnitine, L-aspartic acid, L-glutamic acid, niacinamide, phospho-rylethanolamine). We also found that FANCC can act in an FA-pathway-independent manner in tumor suppression. Collectively, featured-metabolic alterations are readouts of functional mechanisms underlying reduced tumorigenicity driven by FANCC, demonstrating close links among cancer, aging, inflammation and DM.

Metabolites related to purine catabolism and risk of type 2 diabetes incidence; modifying effects of the TCF7L2-rs7903146 polymorphism

Studies examining associations between purine metabolites and type 2 diabetes (T2D) are limited. We prospectively examined associations between plasma levels of purine metabolites with T2D risk and the modifying effects of transcription factor-7-like-2 (TCF7L2) rs7903146 polymorphism on these associations. This is a case-cohort design study within the PREDIMED study, with 251 incident T2D cases and a random sample of 694 participants (641 non-cases and 53 overlapping cases) without T2D at baseline (median follow-up: 3.8 years). Metabolites were semi-quantitatively profiled with LC-MS/MS. Cox regression analysis revealed that high plasma allantoin levels, including allantoin-to-uric acid ratio and high xanthine-to-hypoxanthine ratio were inversely and positively associated with T2D risk, respectively, independently of classical risk factors. Elevated plasma xanthine and inosine levels were associated with a higher T2D risk in homozygous carriers of the TCF7L2-rs7903146 T-allele. The potential mechanisms linking the aforementioned purine metabolites and T2D risk must be also further investigated.

PARP inhibition induces Akt-mediated cytoprotective effects through the formation of a mitochondria-targeted phospho-ATM-NEMO-Akt-mTOR signalosome

PURPOSE

The cytoprotective effect of poly(ADP-ribose) polymerase 1 (PARP1) inhibition is well documented in various cell types subjected to oxidative stress. Previously, we have demonstrated that PARP1 inhibition activates Akt, and showed that this response plays a critical role in the maintenance of mitochondrial integrity and in cell survival. However, it has not yet been defined how nuclear PARP1 signals to cytoplasmic Akt.

METHODS

WRL 68, HeLa and MCF7 cells were grown in culture. Oxidative stress was induced with hydrogen peroxide. PARP was inhibited with the PARP inhibitor PJ34. ATM, mTOR- and NEMO were silenced using specific siRNAs. Cell viability assays were based on the MTT assay. PARP-ATM pulldown experiments were conducted; each protein was visualized by Western blotting. Immunoprecipitation of ATM, phospho-ATM and NEMO was performed from cytoplasmic and mitochondrial cell fractions and proteins were detected by Western blotting. In some experiments, a continually active Akt construct was introduced. Nuclear to cytoplasmic and mitochondrial translocation of phospho-Akt was visualized by confocal microscopy.

RESULTS

Here we present evidence for a PARP1 mediated, PARylation-dependent interaction between ATM and NEMO, which is responsible for the cytoplasmic transport of phosphorylated (thus, activated) ATM kinase. In turn, the cytoplasmic p-ATM and NEMO forms complex with mTOR and Akt, yielding the phospho-ATM-NEMO-Akt-mTOR signalosome, which is responsible for the PARP-inhibition induced Akt activation. The phospho-ATM-NEMO-Akt-mTOR signalosome localizes to the mitochondria and is essential for the PARP-inhibition-mediated cytoprotective effects in oxidatively stressed cells. When the formation of the signalosome is prevented, the cytoprotective effects diminish, but cells can be rescued by constantly active Akt1, further confirming the critical role of Akt activation in cytoprotection.

CONCLUSIONS

Taken together, the data presented in the current paper are consistent with the hypothesis that PARP inhibition suppresses the PARylation of ATM, which, in turn, forms an ATM-NEMO complex, which exits the nucleus, and combines in the cytosol with mTOR and Act, resulting in Act phosphorylation (i.e. activation), which, in turn, produces the cytoprotective action via the induction of Akt-mediated survival pathways. This mechanism can be important in the protective effect of PARP inhibitor in various diseases associated with oxidative stress. Moreover, disruption of the formation or action of the phospho-ATM-NEMO-Akt-mTOR signalosome may offer potential future experimental therapeutic checkpoints.

PARP inhibition protects mitochondria and reduces ROS production via PARP-1-ATF4-MKP-1-MAPK retrograde pathway

Oxidative stress induces DNA breaks and PARP-1 activation which initiates mitochondrial reactive oxygen species (ROS) production and cell death through pathways not yet identified. Here, we show the mechanism by which PARP-1 influences these processes via PARylation of activating transcription factor-4 (ATF4) responsible for MAP kinase phosphatase-1 (MKP-1) expression and thereby regulates MAP kinases. PARP inhibitor, or silencing, of PARP induced MKP-1 expression by ATF4-dependent way, and inactivated JNK and p38 MAP kinases. Additionally, it induced ATF4 expression and binding to cAMP-response element (CRE) leading to MKP-1 expression and the inactivation of MAP kinases. In contrast, PARP-1 activation induced the PARylation of ATF4 and reduced its binding to CRE sequence in vitro. CHIP-qPCR analysis showed that PARP inhibitor increased the ATF4 occupancy at the initiation site of MKP-1. In oxidative stress, PARP inhibition reduced ROS-induced cell death, suppressed mitochondrial ROS production and protected mitochondrial membrane potential on an ATF4 and MKP-1 dependent way. Basically identical results were obtained in WRL-68, A-549 and T24/83 human cell lines indicating that the aforementioned mechanism can be universal. Here, we provide the first description of PARP-1-ATF4-MKP-1-JNK/p38 MAPK retrograde pathway, which is responsible for the regulation of mitochondrial integrity, ROS production and cell death in oxidative stress, and may represent a new mechanism of PARP in cancer therapy since cancer stem cells development is JNK-dependent.

UHPLC-TQ-MS Coupled with Multivariate Statistical Analysis to Characterize Nucleosides, Nucleobases and Amino Acids in Angelicae Sinensis Radix Obtained by Different Drying Methods

To explore the nutrients in roots of Angelica sinensis (Angelicae Sinensis Radix, ASR), a medicinal and edible plant, and evaluate its nutritional value, a rapid and reliable UHPLC-TQ-MS method was established and used to determine the potential nutritional compounds, including nucleosides, nucleobases and amino acids, in 50 batches of ASR samples obtained using two drying methods. The results showed that ASR is a healthy food rich in nucleosides, nucleobases and amino acids, especially arginine. The total average content of nucleosides and nucleobases in all ASR samples was 3.94 mg/g, while that of amino acids reached as high as 61.79 mg/g. Principle component analysis showed that chemical profile differences exist between the two groups of ASR samples prepared using different drying methods, and the contents of nutritional compounds in samples dried with the tempering-intermittent drying processing method (TIDM) were generally higher than those dried using the traditional solar processing method. The above results suggest that ASR should be considered an ideal healthy food and TIDM could be a suitable drying method for ASR when taking nucleosides, nucleobases and amino acids as the major consideration for their known human health benefits.

Mitochondrial poly(ADP-ribose) polymerase: The Wizard of Oz at work

Among multiple members of the poly(ADP-ribose) polymerase (PARP) family, PARP1 accounts for the majority of PARP activity in mammalian cells. Although PARP1 is predominantly localized to the nucleus, and its nuclear regulatory roles are most commonly studied and are the best characterized, several lines of data demonstrate that PARP1 is also present in the mitochondria, and suggest that mitochondrial PARP (mtPARP) plays an important role in the regulation of various cellular functions in health and disease. The goal of the current article is to review the experimental evidence for the mitochondrial localization of PARP1 and its intra-mitochondrial functions, with focus on cellular bioenergetics, mitochondrial DNA repair and mitochondrial dysfunction. In addition, we also propose a working model for the interaction of mitochondrial and nuclear PARP during oxidant-induced cell death. MtPARP is similar to the Wizard of Oz in the sense that it is enigmatic, it has been elusive for a long time and it remains difficult to be interrogated. mtPARP - at least in some cell types - works incessantly "behind the curtains" as an orchestrator of many important cellular functions.

Inhibition of Poly(ADP-Ribose) Polymerase-1 Protects Chronic Alcoholic Liver Injury

Activation of Kupffer cells (KCs) by gut-derived endotoxin plays a pivotal role in the pathogenesis of alcoholic liver diseases (ALD). Limiting the activation of resident KCs attenuates chronic ethanol-induced liver steatosis and injury. Poly (ADP-ribose) polymerase (PARP)-1 is suggested to play a role in a number of chronic inflammatory diseases. In this study, we found a significant increase of hepatic PARP activity in mice with short-term and long-term ethanol-induced ALD. Male mice on a long-term ethanol diet exhibited severe hepatic steatosis and apoptosis and enhanced KC activation and neutrophil infiltration. However, pharmacologic inhibition of PARP activity or genetic depletion of PARP1 significantly attenuated these detrimental effects in vivo. We found that inhibition of PARP1 effectively reduced hepatic expression of genes involved in lipogenesis and elevated hepatic expression of genes involved in lipolysis. Moreover, limited KC activation and neutrophil infiltration were observed in PARP1 knockout mice or PARP inhibitor-treated mice. Furthermore, in vitro experiments found that LPS-induced macrophage activation was limited by PARP inhibitor, and exposure of ethanol-treated hepatocytes to this conditioned medium further decreased the number of apoptotic and steatotic cells. Taken together, these findings suggest that PARP1 inhibition protects against long-term ethanol-induced liver injury, as indicated by limited hepatocytes steatosis, apoptosis, inflammation levels, and neutrophil infiltration, mainly by limiting KC activation during the initiation of ALD.

Chemometrics for comprehensive analysis of nucleobases, nucleosides, and nucleotides in Siraitiae Fructus by hydrophilic interaction ultra high performance liquid chromatography coupled with triple-quadrupole linear ion-trap tandem mass spectrometry

A rapid and sensitive hydrophilic interaction ultra high performance liquid chromatography coupled with triple-quadrupole linear ion-trap tandem mass spectrometry method was validated for the simultaneous determination of 20 nucleobases, nucleosides, and nucleotides (within 3.5 min), and then was employed to test the functional food of Luo-Han-Guo samples. The analysis showed that the Luo-Han-Guo was rich in guanosine and uridine, but contained trace levels of the other target compounds. Chemometrics methods were employed to identify 40 batches of Luo-Han-Guo samples from different cultivated forms, regions and varieties. Unsupervised hierarchical cluster analysis and principal component analysis were used to classify Luo-Han-Guo samples based on the level of the 20 target compounds, and the supervised learning method of counter propagation artificial neural network was utilized to further separate clusters and validate the established model. As a result, the samples could be clustered into three primary groups, in which correlation with cultivated varieties was observed. The present strategy could be applied to the investigation of other edible plants containing nucleobases, nucleosides, or nucleotides.

Poly(ADP-ribose) polymerase 1-sirtuin 1 functional interplay regulates LPS-mediated high mobility group box 1 secretion

Pathophysiological conditions that lead to the release of the prototypic damage-associated molecular pattern molecule high mobility group box 1 (HMGB1) also result in activation of poly(ADP-ribose) polymerase 1 (PARP1; now known as ADP-ribosyl transferase 1 [ARTD1]). Persistent activation of PARP1 promotes energy failure and cell death. The role of poly(ADP-ribosyl)ation in HMGB1 release has been explored previously; however, PARP1 is a versatile enzyme and performs several other functions including cross-talk with another nicotinamide adenine dinucleotide- (NAD(+)) dependent member of the Class III histone deacetylases (HDACs), sirtuin-1 (SIRT1). Previously, it has been shown that the hyperacetylation of HMGB1 is a seminal event prior to its secretion, a process that also is dependent on HDACs. Therefore, in this study, we seek to determine if PARP1 inhibition alters LPS-mediated HMGB1 hyperacetylation and subsequent secretion due to its effect on SIRT1. We demonstrate in an in vitro model that LPS treatment leads to hyperacetylated HMGB1 with concomitant reduction in nuclear HDAC activity. Treatment with PARP1 inhibitors mitigates the LPS-mediated reduction in nuclear HDAC activity and decreases HMGB1 acetylation. By utilizing an NAD(+)-based mechanism, PARP1 inhibition increases the activity of SIRT1. Consequently, there is an increased nuclear retention and decreased extracellular secretion of HMGB1. We also demonstrate that PARP1 physically interacts with SIRT1. Further confirmation of this data was obtained in a murine model of sepsis, that is, administration of PJ-34, a specific PARP1 inhibitor, led to decreased serum HMGB1 concentrations in mice subjected to cecal ligation and puncture (CLP) as compared with untreated mice. In conclusion, our study provides new insights in understanding the molecular mechanisms of HMGB1 secretion in sepsis.

Inputs and outputs of poly(ADP-ribosyl)ation: Relevance to oxidative stress

Oxidative stress can cause DNA breaks which induce activation of the DNA nick sensor enzyme poly(ADP-ribose) polymerase-1 (PARP-1), part of the 17 member PARP enzyme family. PARP-1 modifies target proteins by attaching to them several NAD-derived ADP-ribose units forming poly(ADP-ribose) (PAR) polymers. PARylation controls many cellular processes while intense PARylation may also lead to cell death by various mechanisms. Here we summarize the modes of activation, inhibitors and modulators of PARP-1 and review the cellular functions regulated by the enzyme.

Regulation of mitochondrial poly(ADP-Ribose) polymerase activation by the β-adrenoceptor/cAMP/protein kinase A axis during oxidative stress

We investigated the regulation of mitochondrial poly(ADP-ribose) polymerase 1 (PARP1) by the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) system during oxidative stress in U937 monocytes. Oxidative stress induced an early (10 minutes) mitochondrial DNA damage, and concomitant activation of PARP1 in the mitochondria. These early events were followed by a progressive mitochondrial oxidant production and nuclear PARP1 activation (by 6 hours). These processes led to a functional impairment of mitochondria, culminating in cell death of mixed (necrotic/apoptotic) type. β-Adrenoceptor blockade with propranolol or inhibition of its downstream cAMP/PKA signaling attenuated, while β-adrenoceptor agonists and cAMP/PKA activators enhanced, the oxidant-mediated PARP1 activation. In the presence of cAMP, recombinant PKA directly phosphorylated recombinant PARP1 on serines 465 (in the automodification domain) and 782 and 785 (both in the catalytic domain). Inhibition of the β-adrenergic receptor/cAMP/PKA axis protected against the oxidant-mediated cell injury. Propranolol also suppressed PARP1 activation in peripheral blood leukocytes during bacterial lipopolysaccharide (LPS)-induced systemic inflammation in mice. We conclude that the activation of mitochondrial PARP1 is an early, active participant in oxidant-induced cell death, which is under the control of β-adrenoceptor/cAMP/PKA axis through the regulation of PARP1 activity by PARP1 phosphorylation.

Identification of Nucleosides and Nucleobases from Cultured Cordyceps militaris

Four nucleosides and seven nucleobases were isolated from the BuOH subfraction of the extract of cultured Cordyceps militaris; one of them, 6-acetylpurine (1) is a new natural compound. The structure of 1 was determined on the basis of HR-ESI-MS, and 1D and 2D NMR spectroscopic analysis.

Hydrogen peroxide induces adaptive response and differential gene expression in human embryo lung fibroblast cells

Hydrogen peroxide (H2 O2 ), a substance involved in cellular oxidative stress, has been observed to induce an adaptive response, which is characterized by a protection against the toxic effect of H2 O2 at higher concentrations. However, the molecular mechanism for the adaptive response remains unclear. In particular, the existing reports on H2 O2 -induced adaptive response are limited to animal cells and human tumor cells, and relatively normal human cells have never been observed for an adaptive response to H2 O2 . In this study, a human embryo lung fibroblast (MRC-5) cell line was used to model an adaptive response to H2 O2 , and the relevant differential gene expressions by using fluoro mRNA differential display RT-PCR. The results showed significant suppression of cytotoxicity of H2 O2 (1100 μM, 1 h) after pretreatment of the cells with H2 O2 at lower concentrations (0.088-8.8 μM, 24 h), as indicated by cell survival, lactate dehydrogenase release, and the rate of apoptotic cells. Totally 60 mRNA components were differentially expressed compared to untreated cells, and five of them (sizing 400-600 bp) which demonstrated the greatest increase in expression were cloned and sequenced. They showed identity with known genes, such as BCL-2, eIF3S5, NDUFS4, and RPS10. Real time RT-PCR analysis of the five genes displayed a pattern of differential expression consistent with that by the last method. These five genes may be involved in the induction of adaptive response by H2 O2 in human cells, at least in this particular cell type.

Profiling transcriptomic response of Enchytraeus albidus to Cu and Ni: comparison with Cd and Zn

Metals are among the most common contaminants in soils in Europe. Although their effects are relatively well known regarding survival and reproduction to soil invertebrates, their mode of action is poorly understood. Enchytraeus albidus is a model organism in ecotoxicology and with the development of a gene library for this species, transcriptomic studies are now possible. The main aim of this study is to understand the Cu and Ni mechanisms of response in E. albidus, in comparison with Cd and Zn (already studied). E. albidus were exposed to Cu and Ni for 4 days to the reproduction effect concentrations EC50 and EC90. Results indicate that Cu and Ni have similar mechanisms of toxicity. When comparing four elements (hierarchical clustering) it was possible to observe a clear separation of Cd from all other metals. This separation correlates with the available information from other species regarding the toxicokinetics of the tested elements.

Therapeutic applications of PARP inhibitors: anticancer therapy and beyond

The aim of this article is to describe the current and potential clinical translation of pharmacological inhibitors of poly(ADP-ribose) polymerase (PARP) for the therapy of various diseases. The first section of the present review summarizes the available preclinical and clinical data with PARP inhibitors in various forms of cancer. In this context, the role of PARP in single-strand DNA break repair is relevant, leading to replication-associated lesions that cannot be repaired if homologous recombination repair (HRR) is defective, and the synthetic lethality of PARP inhibitors in HRR-defective cancer. HRR defects are classically associated with BRCA1 and 2 mutations associated with familial breast and ovarian cancer, but there may be many other causes of HRR defects. Thus, PARP inhibitors may be the drugs of choice for BRCA mutant breast and ovarian cancers, and extend beyond these tumors if appropriate biomarkers can be developed to identify HRR defects. Multiple lines of preclinical data demonstrate that PARP inhibition increases cytotoxicity and tumor growth delay in combination with temozolomide, topoisomerase inhibitors and ionizing radiation. Both single agent and combination clinical trials are underway. The final part of the first section of the present review summarizes the current status of the various PARP inhibitors that are in various stages of clinical development. The second section of the present review summarizes the role of PARP in selected non-oncologic indications. In a number of severe, acute diseases (such as stroke, neurotrauma, circulatory shock and acute myocardial infarction) the clinical translatability of PARP inhibition is supported by multiple lines of preclinical data, as well as observational data demonstrating PARP activation in human tissue samples. In these disease indications, PARP overactivation due to oxidative and nitrative stress drives cell necrosis and pro-inflammatory gene expression, which contributes to disease pathology. Accordingly, multiple lines of preclinical data indicate the efficacy of PARP inhibitors to preserve viable tissue and to down-regulate inflammatory responses. As the clinical trials with PARP inhibitors in various forms of cancer progress, it is hoped that a second line of clinical investigations, aimed at testing of PARP inhibitors for various non-oncologic indications, will be initiated, as well.

Hydrophilic interaction ultra-high performance liquid chromatography coupled with triple quadrupole mass spectrometry for determination of nucleotides, nucleosides and nucleobases in Ziziphus plants

In this study, a rapid and sensitive analytical method was developed for the determination of 20 nucleobases, nucleosides and nucleotides in Ziziphus plants at trace levels by using hydrophilic interaction ultra-high performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (HILIC-UHPLC-TQ-MS/MS) in multiple-reaction monitoring (MRM) mode. Under the optimized chromatographic conditions, good separation for 20 target compounds were obtained on a UHPLC Amide column with sub-2μm particles within 10min. The overall LODs and LOQs were between 0.11-3.12ngmL(-1) and 0.29-12.48ngmL(-1) for the 20 analytes, respectively. It is the first report about simultaneous analysis of nucleobases, nucleosides and nucleotides in medicinal plants using HILIC-UHPLC-TQ-MS/MS method, which affords good linearity, precision, repeatability and accuracy. The developed method was successfully applied to Ziziphus plant (Z. jujuba, Z. jujuba var. spinosa and Z. mauritiana) samples. The analysis showed that the fruits and leaves of Ziziphus plants are rich in nucleosides and nucleobases as well as nucleotides, and could be selected as the healthy food resources. Our results in present study suggest that HILIC-UHPLC-TQ-MS/MS method could be employed as a useful tool for quality assessment of the samples from the Ziziphus plants as well as other medicinal plants or food samples using nucleotides, nucleosides and nucleobases as markers.

Antioxidant and anti-inflammatory effects in RAW264.7 macrophages of malvidin, a major red wine polyphenol

Background

Red wine polyphenols can prevent cardiovascular and inflammatory diseases. Resveratrol, the most extensively studied constituent, is unlikely to solely account for these beneficial effects because of its rather low abundance and bioavailability. Malvidin is far the most abundant polyphenol in red wine; however, very limited data are available about its effect on inflammatory processes and kinase signaling pathways.

Methods & Findings

The present study was carried out by using RAW 264.7 macrophages stimulated by bacterial lipopolysaccharide in the presence and absence of malvidin. From the cells, activation of nuclear factor-kappaB, mitogen-activated protein kinase, protein kinase B/Akt and poly ADP-ribose polymerase, reactive oxygen species production, mitogen-activated protein kinase phosphatase-1 expression and mitochondrial depolarization were determined. We found that malvidin attenuated lipopolysaccharide-induced nuclear factor-kappaB, poly ADP-ribose polymerase and mitogen-activated protein kinase activation, reactive oxygen species production and mitochondrial depolarization, while upregulated the compensatory processes; mitogen-activated protein kinase phosphatase-1 expression and Akt activation.

Conclusions

These effects of malvidin may explain the previous findings and at least partially account for the positive effects of moderate red wine consumption on inflammation-mediated chronic maladies such as obesity, diabetes, hypertension and cardiovascular disease.

Role of poly(ADP-ribosyl)ation in a 'two-hit' model of hypoxia and oxidative stress in human A549 epithelial cells in vitro

A preceding hypoxic insult can sensitize the cells or the organism to a subsequent, second insult. The aim of the present study was to investigate the molecular mechanism of this phenomenon (often termed ‘two-hit’ injury paradigm), in an in vitro model of hypoxia/oxidative stress injury in A549 epithelial cells, with special emphasis on the role of the nuclear enzyme poly(ADP-ribose) polymerase-1 (PARP-1) in the process. Pre-exposure of the cells to 24 h hypoxia significantly reduced intracellular glutathione (GSH) levels, reduced mitochondrial activity and adenosine triphosphate (ATP) levels. However pre-exposure to hypoxia failed to induce any change in PARP-1 expression and activation, DNA single-strand breaks or plasma membrane integrity. Pre-exposure to hypoxia markedly increased the sensitivity of the cells to subsequent oxidative stress-induced DNA damage. Hydrogen peroxide (H₂O₂) induced a concentration-dependent increase in DNA breakage, PARP activation, depletion of intracellular ATP, inhibition of mitochondrial activity and two distinct parameters that quantify the breakdown of plasma membrane integrity (propidium iodide uptake or lactate dehydrogenase release). PARP-1 activation played a significant role in the H₂O₂-induced cell death response because PARP activation, depletion of intracellular ATP, inhibition of mitochondrial activity, and the breakdown of plasma membrane integrity were attenuated in cells with permanently silenced PARP-1. Based on measurement of the endogenous antioxidant GSH, we hypothesized that the mechanism of hypoxia-mediated enhancement of H₂O₂ involves depletion of the GSH during the hypoxic period, which renders the cells more sensitive to a subsequent DNA single-strand break elicited by H₂O₂. DNA strand breakage then activates PARP-1, leading to the inhibition of mitochondrial function, depletion of ATP and cell necrosis. PARP-1 deficiency protects against the cytotoxicity, to a lesser degree, by protecting against GSH depletion during the hypoxic period, and, to a larger degree, by maintaining mitochondrial function and preserving intracellular ATP levels during the subsequent oxidative stress period.

The jujube (Ziziphus jujuba Mill.) fruit: a review of current knowledge of fruit composition and health benefits

The nutritional jujube ( Ziziphus jujube Mill.) fruit belonging to the Rhamnaceous family grows mostly in Europe, southern and eastern Asia, and Australia, especially the inland region of northern China. Jujube has a long history of usage as a fruit and remedy. The main biologically active components are vitamin C, phenolics, flavonoids, triterpenic acids, and polysaccharides. Recent phytochemical studies of jujube fruits have shed some light on their biological effects, such as the anticancer, anti-inflammatory, antiobesity, immunostimulating, antioxidant, hepatoprotective, and gastrointestinal protective activities and inhibition of foam cell formation in macrophages. A stronger focus on clinical studies and phytochemical definition of jujube fruits will be essential for future research efforts. This review may be useful for predicting other medicinal uses and potential drug or food interactions and may be beneficial for people living where the jujube fruits are prevalent and health care resources are scarce.

Poly(ADP-ribose) signaling in cell death

Poly(ADP-ribosyl)ation (PARylation) is a reversible protein modification carried out by the concerted actions of poly(ADP-ribose) polymerase (PARP) enzymes and poly(ADP-ribose) (PAR) decomposing enzymes such as PAR glycohydrolase (PARG) and ADP-ribosyl hydrolase 3 (ARH3). Reversible PARylation is a pleiotropic regulator of various cellular functions but uncontrolled PARP activation may also lead to cell death. The cellular demise pathway mediated by PARylation in oxidatively stressed cells has been described almost thirty years ago. However, the underlying molecular mechanisms have only begun to emerge relatively recently. PARylation has been implicated in necroptosis, autophagic cell death but its role in extrinsic and intrinsic apoptosis appears to be less predominant and depends largely on the cellular model used. Currently, three major pathways have been made responsible for PARP-mediated necroptotic cell death: (1) compromised cellular energetics mainly due to depletion of NAD, the substrate of PARPs; (2) PAR mediated translocation of apoptosis inducing factor (AIF) from mitochondria to nucleus (parthanatos) and (3) a mostly elusive crosstalk between PARylation and cell death/survival kinases and phosphatases. Here we review how these PARP-mediated necroptotic pathways are intertwined, how PARylation may contribute to extrinsic and intrinsic apoptosis and discuss recent developments on the role of PARylation in autophagy and autophagic cell death.

Anti-inflammatory effects of inosine in allergic lung inflammation in mice: evidence for the participation of adenosine A2A and A 3 receptors

Inosine, a naturally occurring purine formed from the breakdown of adenosine, is associated with immunoregulatory effects. Evidence shows that inosine modulates lung inflammation and regulates cytokine generation. However, its role in controlling allergen-induced lung inflammation has yet to be identified. In this study, we aimed to investigate the role of inosine and adenosine receptors in a murine model of lung allergy induced by ovalbumin (OVA). Intraperitoneal administration of inosine (0.001-10 mg/kg, 30 min before OVA challenge) significantly reduced the number of leukocytes, macrophages, lymphocytes and eosinophils recovered in the bronchoalveolar lavage fluid of sensitized mice compared with controls. Interestingly, our results showed that pre-treatment with the selective A2A receptor antagonist (ZM241385), but not with the selective A2B receptor antagonist (alloxazine), reduced the inhibitory effects of inosine against macrophage count, suggesting that A2A receptors mediate monocyte recruitment into the lungs. In addition, the pre-treatment of mice with selective A3 antagonist (MRS3777) also prevented inosine effects against macrophages, lymphocytes and eosinophils. Histological analysis confirmed the effects of inosine and A2A adenosine receptors on cell recruitment and demonstrated that the treatment with ZM241385 and alloxazine reverted inosine effects against mast cell migration into the lungs. Accordingly, the treatment with inosine reduced lung elastance, an effect related to A2 receptors. Moreover, inosine reduced the levels of Th2-cytokines, interleukin-4 and interleukin-5, an effect that was not reversed by A2A or A2B selective antagonists. Our data show that inosine acting on A2A or A3 adenosine receptors can regulate OVA-induced allergic lung inflammation and also implicate inosine as an endogenous modulator of inflammatory processes observed in the lungs of asthmatic patients.

Adenosine and inosine exert cytoprotective effects in an in vitro model of liver ischemia-reperfusion injury

Liver ischemia represents a common clinical problem. In the present study, using an in vitro model of hepatic ischemia-reperfusion injury, we evaluated the potential cytoprotective effect of the purine metabolites, such as adenosine and inosine, and studied the mode of their pharmacological actions. The human hepatocellular carcinoma-derived cell line HepG2 was subjected to combined oxygen-glucose deprivation (COGD; 0-14-24 h), followed by re-oxygenation (0-4-24 h). Adenosine or inosine (300-1,000 µM) were applied in pretreatment. Cell viability and cytotoxicity were measured by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide and lactate dehydrogenase methods, respectively. The results showed that both adenosine and inosine exerted cytoprotective effects, and these effects were not related to receptor-mediated actions, since they were not prevented by selective adenosine receptor antagonists. On the other hand, the adenosine deaminase inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine hydrochloride (EHNA, 10 µM) markedly and almost fully reversed the protective effect of adenosine during COGD, while it did not influence the cytoprotective effect of inosine in the same assay conditions. These results suggest that the cytoprotective effects are related to intracellular actions, and, in the case of adenosine also involve intracellular conversion to inosine. The likely interpretation of these findings is that inosine serves as an alternative source of energy to produce ATP during hypoxic conditions. The protective effects are also partially dependent on adenosine kinase, as the inhibitor 4-amino-5-(3-bromophenyl)-7-(6‑morpholino-pyridin-3-yl)pyrido[2,3-d]pyrimidine, 2HCl (ABT 702, 30 µM) significantly reversed the protective effect of both adenosine and inosine during hypoxia and re-oxygenation. Collectively, the current results support the view that during hypoxia, adenosine and inosine exert cytoprotective effects via receptor-independent, intracellular modes of action, which, in part, depend on the restoration of cellular bioenergetics. The present study supports the view that testing of inosine for protection against various forms of warm and cold liver ischemia is relevant.

Determination of nucleosides and nucleobases in the pollen of Typha angustifolia by UPLC-PDA-MS

INTRODUCTION

The pollen of Typha angustifolia L. has been used traditionally for the treatment of dysmenorrhea, stranguria and metrorrhagia in China. Recently, nucleosides and nucleobases have been proven as important bioactive compounds. Exploration of the nucleoside and nucleobase profiles from the pollen of T. angustifolia is important for improving its therapeutic value and could be convenient for its quality evaluation.

OBJECTIVE

To establish an UPLC-PDA-MS method for simultaneous determination of nucleosides and nucleobases in the pollen of T. angustifolia.

METHODOLOGY

The analysis was performed on an Acuity UPLCHSS T3 column with a gradient elution of 5 mM ammonium acetate and methanol solution at a flow rate of 0.3 mL/min.

RESULTS

Satisfactory separation of these compounds was obtained in less than 12 min. All calibration curves showed good linear regression (r²  > 0.9995). The method provided good accuracy, precision, recovery, and sensitivity for the quantification of the 10 compounds analysed.

CONCLUSION

The UPLC method established is very helpful for optimising their content and could be convenient for quality evaluation of the pollen of T. angustifolia, which has not been reported as far as we are aware.

Effects of inosine on reperfusion injury after cardiopulmonary bypass

Objective

Inosine, a break-down product of adenosine has been recently shown to exert inodilatory and anti-inflammatory properties. Furthermore inosine might be a key substrate of pharmacological post-conditioning. In the present pre-clinical study, we investigated the effects of inosine on cardiac function during reperfusion in an experimental model of cardioplegic arrest and extracorporal circulation.

Methods

Twelve anesthetized dogs underwent hypothermic cardiopulmonary bypass. After 60 minutes of hypothermic cardiac arrest, reperfusion was started after application of either saline vehicle (control, n = 6), or inosine (100 mg/kg, n = 6). Left ventricular end-systolic pressure volume relationship (ESPVR) was measured by a combined pressure-volume-conductance catheter at baseline and after 60 minutes of reperfusion. Left anterior descendent coronary blood flow (CBF), endothelium-dependent vasodilatation to acetylcholine (ACh) and endothelium-independent vasodilatation to sodium nitroprusside (SNP) were also determined.

Results

The administration of inosine led to a significantly better recovery (given as percent of baseline) of ESPVR 90 ± 9% vs. 46 ± 6%, p < 0.05. CBF and was also significantly higher in the inosine group (56 ± 8 vs. 23 ± 4, ml/min, p < 0.05). While the vasodilatatory response to SNP was similar in both groups, ACh resulted in a significantly higher increase in CBF (58 ± 6% vs. 25 ± 5%, p < 0.05) in the inosine group.

Conclusions

Application of inosine improves myocardial and endothelial function after cardiopulmonary bypass with hypothermic cardiac arrest.

Characterization of nucleosides and nucleobases in fruits of Ziziphus jujuba by UPLC-DAD-MS

The fruit of Ziziphus jujuba , named dazao in Chinese, has been utilized as food as well as crude drugs in China for thousands of years. To explore the profiles of the nucleosides and nucleobases in this fruit, an ultraperformance liquid chromatograph coupled with a photodiode array detector and electrospray ionization-mass spectrometer method (UPLC-DAD-MS) has been established and validated in this paper. The validated method was successfully applied for the simultaneous characterization and quantitation of 9 nucleosides and nucleobases in 49 dazao samples, which comprised 43 cultivars from 26 cultivation regions. Furthermore, principal component analysis (PCA) was performed to classify the samples on the basis of the contents of the nine analyzed compounds. The results showed that almost all of these dazao samples were rich in nucleosides and nucleobases, although their contents were obviously various, and the proposed method could serve as a prerequisite for quality control of jujube products.

Improvement of mitochondrial energy and oxidative balance during intestinal differentiation

Mitochondria vary in their number and function, but how these variations are associated with intestinal cell differentiation remains elusive. The object of this study was to investigate the underlying mechanisms of inosine-mediated intestinal cell maturation, analysing the effects of this nutrient on metabolic functionality, mitochondrial biogenesis and mitochondrial function in human colonic cells. The role of oxidative stress in the control of intestinal cell growth was also explored. We report the novel finding that inosine-mediated differentiation improves aerobic metabolism through an increase in mitochondrial bioenergetics and biogenesis in colonic cells, which probably confers them greater resistance to cytotoxic oxidative stress.

Cell-free plasma DNA and purine nucleotide degradation markers following weightlifting exercise

The present study aimed to investigate the acute effects of a single bout of high-intensive strength training on the production of cell-free plasma DNA (cf-DNA), as well as on the degradation of purine nucleotides as assessed by the concentration of xanthine (XA) and hypoxanthine (HX) in urine and serum. Twelve trained weightlifters performed six sets of six lifting exercises with 90-95% of the one repetition maximum. Blood samples and urine were obtained 1 h before training, immediately after finishing the exercise session and following 2 h of recovery. Cf-DNA, HX, and XA (in serum) significantly increased (P < 0.05-P < 0.001) immediately after heavy lifting exercise when compared with baseline levels, and significantly decreased (P < 0.05-P < 0.001) after 2 h of recovery. These results indicate that, cf-DNA and oxypurines might be relevant biomarkers for cellular damage, mechanical, energetic, and/or ischemic stress in context with exercise.

Cytoprotective effects of adenosine and inosine in an in vitro model of acute tubular necrosis

BACKGROUND AND PURPOSE

We have established an in vitro model of acute tubular necrosis in rat kidney tubular cells, using combined oxygen-glucose deprivation (COGD) and screened a library of 1280 pharmacologically active compounds for cytoprotective effects.

EXPERIMENTAL APPROACH

We used in vitro cell-based, high throughput, screening, with cells subjected to COGD using hypoxia chambers, followed by re-oxygenation. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and the Alamar Blue assay measured mitochondrial respiration and the lactate dehydrogenase assay was used to indicate cell death. ATP levels were measured using a luminometric assay.

KEY RESULTS

Adenosine markedly reduced cellular injury, with maximal cytoprotective effect at 100 microM and an EC(50) value of 14 microM. Inosine was also found to be cytoprotective. The selective A(3) adenosine receptor antagonist MRS 1523 attenuated the protective effects of adenosine and inosine, while an A(3) adenosine receptor agonist provided a partial protective effect. Adenosine deaminase inhibition attenuated the cytoprotective effect of adenosine but not of inosine during COGD. Inhibition of adenosine kinase reduced the protective effects of both adenosine and inosine during COGD. Pretreatment of the cells with adenosine or inosine markedly protected against the fall in cellular ATP content in the cells subjected to COGD.

CONCLUSIONS AND IMPLICATIONS

The cytoprotection elicited by adenosine and inosine in a model of renal ischaemia involved both interactions with cell surface adenosine receptors on renal tubular epithelial cells and intracellular metabolism and conversion of adenosine to ATP.

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.