Increased expression of an inducible isoform of nitric oxide synthase and the formation of peroxynitrite in colonic mucosa of patients with active ulcerative colitis

Cimicifuga heracleifolia kom. Attenuates ulcerative colitis through the PI3K/AKT/NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cimicifuga heracleifolia Kom. (C. heracleifolia) has demonstrated efficacy in treating gastrointestinal disorders, including splenasthenic diarrhea. Ulcerative colitis (UC), a chronic inflammatory bowel disease, shares similarities with splenasthenic diarrhea. However, the pharmacological effects of C. heracleifolia on UC and the underlying mechanisms remain unexplored.

AIM OF THE STUDY

The present study investigates the therapeutic potential and mechanisms of C. heracleifolia in UC.

METHODS

Initially, network pharmacology analysis, encompassing ingredient screening, target prediction, protein-protein interaction (PPI) network analysis, and enrichment analysis, was employed to predict the mechanisms of C. heracleifolia. The findings were further validated using transcriptomics and functional assays in a dextran sulfate sodium (DSS)-induced UC model. Additionally, bioactive compounds were identified through surface plasmon resonance (SPR) analysis, molecular docking, and cell-based assays.

RESULTS

A total of 52 ingredients of C. heracleifolia were screened, and 32 key targets were identified within a PPI network comprising 285 potential therapeutic targets. Enrichment analysis indicated that the anti-UC effects of C. heracleifolia are mediated through immune response modulation and the inhibition of inflammatory signaling pathways. In vivo experiments showed that C. heracleifolia mitigated histological damage in the colon, reduced the expression of phosphorylated Akt1, nuclear factor-kappa B (NF-κB) p65, and inhibitor of Kappa B kinase α/β (IKKα/β), suppressed the content of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and enhanced the expression of tight junction proteins. Moreover, cimigenoside, caffeic acid, and methyl caffeate were identified as the bioactive constituents responsible for the UC treatment effects of C. heracleifolia.

CONCLUSIONS

In summary, this study is the first to demonstrate that C. heracleifolia exerts therapeutic effects on UC by enhancing the intestinal mucosal barrier and inhibiting the phosphatidylinositol 3-kinase (PI3K)/AKT/NF-κB signaling pathway. These findings offer valuable insights into the clinical application of C. heracleifolia for UC management.

Inflammatory bowel disease and carcinogenesis

Colorectal cancer (CRC) is the third most common cancer and the fourth most common cause of cancer mortality worldwide. Colitis-associated colorectal cancer (CAC) is a subtype of CRC associated with inflammatory bowel disease (IBD). It is well known that individuals with IBD have a 2-3 times higher risk of developing CRC than those who do not, rendering CAC a major cause of death in this group. Although the etiology and pathogenesis of CAC are incompletely understood, animal models of chronic inflammation and human cohort data indicate that changes in the intestinal environment, including host response dysregulation and gut microbiota perturbations, may contribute to the development of CAC. Genomic alterations are a hallmark of CAC, with patterns that are distinct from those in sporadic CRC. The discovery of the biological changes that underlie the development of CAC is ongoing; however, current data suggest that chronic inflammation in IBD increases the risk of developing CAC. Therefore, a deeper understanding of the precise mechanisms by which inflammation triggers genetic alterations and disrupts intestinal homeostasis may provide insight into novel therapeutic strategies for the prevention of CAC.

Umbelliferone ameliorates ulcerative colitis induced by acetic acid via modulation of TLR4/NF-κB-p65/iNOS and SIRT1/PPARγ signaling pathways in rats

Ulcerative colitis (UC) is a common chronic, idiopathic inflammatory bowel disease associated with inflammatory perturbation and oxidative stress. Umbelliferone (UMB) is a potent anti-inflammatory and antioxidant coumarin derivative. Depending on the possible mechanisms, we aimed to explore and elucidate the therapeutic potential of UMB on UC-inflammatory response and oxidative injury-induced via intrarectal administration of acetic acid (AA) in rats. Animals were assigned into four groups: control group, UMB (30 mg/kg, oral)-treated group, AA-induced colitis model group (2 ml of AA; 3% v/v), and colitis treated with UMB group. The results showed that UMB improved macroscopic and histological tissue injury caused by the AA. Mechanistically, UMB reduced the elevated colonic TNF-α, IL-6, MPO, and VCAM-1 and downregulated the gene and protein expression of TLR4, NF-κB, and iNOS signaling factors, exhibiting potent anti-inflammatory effects. Moreover, UMB upregulated the gene and protein expression of both SIRT1 and PPARγ signaling pathways, thereby inhibiting both oxidative injury and inflammatory response. Conclusively, UMB protected rats against AA-induced UC by suppressing the TLR4/NF-κB-p65/iNOS signaling pathway and promoting the SIRT1/PPARγ signaling. Our results showed the effectiveness of UMB in alleviating the pathogenesis of UC and introduced it as a possible therapeutic applicant for clinical application.

The Role of Gut Microbiota and Metabolites in Obesity-Associated Chronic Gastrointestinal Disorders

The gut microbiota is a complex community of microorganisms that has become a new focus of attention due to its association with numerous human diseases. Research over the last few decades has shown that the gut microbiota plays a considerable role in regulating intestinal homeostasis, and disruption to the microbial community has been linked to chronic disease conditions such as inflammatory bowel disease (IBD), colorectal cancer (CRC), and obesity. Obesity has become a global pandemic, and its prevalence is increasing worldwide mostly in Western countries due to a sedentary lifestyle and consumption of high-fat/high-sugar diets. Obesity-mediated gut microbiota alterations have been associated with the development of IBD and IBD-induced CRC. This review highlights how obesity-associated dysbiosis can lead to the pathogenesis of IBD and CRC with a special focus on mechanisms of altered absorption of short-chain fatty acids (SCFAs).

Cells and mediators of inflammation as effectors of epithelial repair in the inflamed intestine

Mucosal and histological healing have become the gold standards for assessing the efficacy of therapy in patients living with inflammatory bowel diseases (IBD). Despite these being the accepted goals in therapy, the mechanisms that underlie the healing of the mucosa after an inflammatory insult are not well understood, and many patients fail to meet this therapeutic endpoint. Here we review the emerging evidence that mediators (e.g., prostaglandins, cytokines, proteases, reactive oxygen, and nitrogen species) and innate immune cells (e.g., neutrophils and monocytes/macrophages), that are involved in the initiation of the inflammatory response, are also key players in the mechanisms underlying mucosal healing to resolve chronic inflammation in the colon. The dual function mediators comprise an inflammation/repair program that returns damaged tissue to homeostasis. Understanding details of the dual mechanisms of these mediators and cells may provide the basis for the development of drugs that can help to stimulate epithelial repair in patients affected by IBD.

Neoechinulins: Molecular, cellular, and functional attributes as promising therapeutics against cancer and other human diseases

Neoechinulins are fungal and plant-derived chemicals extracted from Microsporum sp., Eurotium rubrum, Aspergillus sp., etc. Two analogues of neoechinulin, i.e., A and B, exerted extensive pharmacological properties described in this review. Neoechinulin is an indole alkaloid and has a double bond between C8/C9, which tends to contribute to its cytoprotective nature. Neoechinulin A exhibits protection to PC12 cells against nitrosative stress via increasing NAD(P)H reserve capacity and decreasing cellular GSH levels. It also confers protection via rescuing PC12 cells from rotenone-induced stress by lowering LDH leakage. This compound has great positive potential against neurodegenerative diseases by inhibiting SIN-1 induced cell death in neuronal cells. Together with these, neoechinulin A tends to inhibit Aβ42-induced microglial activation and confers protection against neuroinflammation. Alongside, it also inhibits cervical cancer cells by caspase-dependent apoptosis and via upregulation of apoptosis inducing genes like Bax, it suppresses LPS-induced inflammation in RAW264.7 macrophages and acts as an antidepressant. Whereas, another analogue, Neoechinulin B tends to interfere with the cellular mechanism thereby, inhibiting the entry of influenza A virus and it targets Liver X receptor (LXR) and decreases the infection rate of Hepatitis C. The present review describes the pharmaceutical properties of neoechinulins with notes on their molecular, cellular, and functional basis and their therapeutic properties.

Arginine-dependent immune responses

A growing body of evidence indicates that, over the course of evolution of the immune system, arginine has been selected as a node for the regulation of immune responses. An appropriate supply of arginine has long been associated with the improvement of immune responses. In addition to being a building block for protein synthesis, arginine serves as a substrate for distinct metabolic pathways that profoundly affect immune cell biology; especially macrophage, dendritic cell and T cell immunobiology. Arginine availability, synthesis, and catabolism are highly interrelated aspects of immune responses and their fine-tuning can dictate divergent pro-inflammatory or anti-inflammatory immune outcomes. Here, we review the organismal pathways of arginine metabolism in humans and rodents, as essential modulators of the availability of this semi-essential amino acid for immune cells. We subsequently review well-established and novel findings on the functional impact of arginine biosynthetic and catabolic pathways on the main immune cell lineages. Finally, as arginine has emerged as a molecule impacting on a plethora of immune functions, we integrate key notions on how the disruption or perversion of arginine metabolism is implicated in pathologies ranging from infectious diseases to autoimmunity and cancer.

Genetic Pathogenesis of Inflammation-Associated Cancers in Digestive Organs

Epidemiological, clinical, and biological studies convincingly demonstrate that chronic inflammation predisposes to the development of human cancers. In digestive organs, inflammation-associated cancers include colitis-associated colorectal cancers, Helicobacter pylori-associated gastric cancer, as well as Barrett's esophagus and esophageal adenocarcinoma associated with chronic duodenogastric-esophageal reflux. Cancer is a genomic disease, and stepwise accumulation of genetic and epigenetic alterations of tumor-related genes leads to the development of tumor cells. Recent genome analyses show that genetic alterations, which are evoked by inflammation, are latently accumulated in inflamed epithelial cells of digestive organs. Production of reactive oxygen and aberrant expression of activation-induced cytidine deaminase, a nucleotide-editing enzyme, could be induced in inflamed gastrointestinal epithelial cells and play a role as a genomic modulator of inflammation-associated carcinogenesis. Understanding the molecular linkage between inflammation and genetic alterations will open up a new field of tumor biology and provide a novel strategy for the prevention of inflammation-associated tumorigenesis.

Heparin-Coated Albumin Nanoparticles for Drug Combination in Targeting Inflamed Intestine

Targeting areas of inflammation offers potential therapeutic and diagnostic benefits by maximizing drug and imaging marker on-target effects while minimizing systemic exposure that can be associated with adverse side effects. This strategy is particularly beneficial in the management of inflammatory bowel disease (IBD). Here an inflammation-targeting (IT) approach based on heparin-coated human serum albumin nanoparticles (HEP-HSA NPs) that utilize the increased intestinal permeability and changes in electrostatic interaction at the site of intestinal inflammation is described. Using small-molecule and biologic drugs as a model for drug combination, the HEP-HSA NPs demonstrate the capacity to load both drugs simultaneously; the dual-drug loaded HEP-HSA NPs exhibit a higher anti-inflammatory effect than both of the single-drug loaded NPs in vitro and selectively bind to inflamed intestine after enema administration in vivo in a murine model of colitis. Importantly, analyses of the physicochemical characteristics and targeting capacities of these NPs indicate that HEP coating modulates NP binding to the inflamed intestine, providing a foundation for future IT-NP formulation development.

Experimental and Clinical Evidence of Endothelial Dysfunction in Inflammatory Bowel Disease

The endothelium has a crucial role in proper hemodynamics. Inflammatory bowel disease (IBD) is mainly a chronic inflammatory condition of the gastrointestinal tract. However, considerable evidence points to high cardiovascular risk in patients with IBD. This review positions the basic mechanisms of endothelial dysfunction in the IBD setting (both clinical and experimental). Furthermore, we review the main effects of drugs used to treat IBD in endothelial (dys)function. Moreover, we leave challenging points for enlarging the therapeutic arsenal for IBD with new or repurposed drugs that target endothelial dysfunction besides inflammation.

Interventions of natural and synthetic agents in inflammatory bowel disease, modulation of nitric oxide pathways

Inflammatory bowel disease (IBD) refers to a group of disorders characterized by chronic inflammation of the gastrointestinal (GI) tract. The elevated levels of nitric oxide (NO) in serum and affected tissues; mainly synthesized by the inducible nitric oxide synthase (iNOS) enzyme; can exacerbate GI inflammation and is one of the major biomarkers of GI inflammation. Various natural and synthetic agents are able to ameliorate GI inflammation and decrease iNOS expression to the extent comparable with some IBD drugs. Thereby, the purpose of this study was to gather a list of natural or synthetic mediators capable of modulating IBD through the NO pathway. Electronic databases including Google Scholar and PubMed were searched from 1980 to May 2018. We found that polyphenols and particularly flavonoids are able to markedly attenuate NO production and iNOS expression through the nuclear factor κB (NF-κB) and JAK/STAT signaling pathways. Prebiotics and probiotics can also alter the GI microbiota and reduce NO expression in IBD models through a broad array of mechanisms. A number of synthetic molecules have been found to suppress NO expression either dependent on the NF-κB signaling pathway (i.e., dexamethasone, pioglitazone, tropisetron) or independent from this pathway (i.e., nicotine, prednisolone, celecoxib, β-adrenoceptor antagonists). Co-administration of natural and synthetic agents can affect the tissue level of NO and may improve IBD symptoms mainly by modulating the Toll like receptor-4 and NF-κB signaling pathways.

Time-Dependent Indirect Antioxidative Effects of Oat Beta-Glucans on Peripheral Blood Parameters in the Animal Model of Colon Inflammation

Background: Oat beta-glucans are polysaccharides, belonging to soluble fiber fraction, that show a wide spectrum of biological activity. The aim of this study was to evaluate the time-dependent antioxidative effect of chemically pure oat beta-glucan fractions, characterized by different molar mass, which were fed to animals with early stage of 2,4,6-trinitrobenzene sulfonic acid (TNBS) - induced colitis. Methods: The study was conducted on 150 adult male Sprague Dawley rats assigned to two groups—healthy control (H) and colitis (C) with colon inflammation induced by per rectum administration of TNBS. The animals from both groups were divided into 3 nutritional subgroups, receiving for 3, 7 or 21 days AIN-93M feed without beta-glucan (βG−) or with 1% (w/w) low molar mass oat beta-glucan (βGl+) or 1% (w/w) high molar mass oat beta-glucan (βGh+). After 3, 7 and 21 days, the animals were euthanized, peripheral blood was collected from the heart for further analysis. Results: The results of analyses performed on blood samples showed small changes in lymphocytes count and red blood cell parameters such as the number of red blood cell, mean corpuscular hemoglobin concentration and mean corpuscular volume (RBC, MCHC, MCV respectively) as well as normalization of antioxidant potential accompanying moderate inflammatory state of colon mucosa and submucosa. Conclusion: Oat beta-glucans exert an indirect antioxidant effect in animals with TNBS-induced colitis, with greater effectiveness in removing systemic effects of colon inflammation found for low molar mass oat beta-glucan.

Somatic inflammatory gene mutations in human ulcerative colitis epithelium

With ageing, normal human tissues experience an expansion of somatic clones that carry cancer mutations^1-7. However, whether such clonal expansion exists in the non-neoplastic intestine remains unknown. Here, using whole-exome sequencing data from 76 clonal human colon organoids, we identify a unique pattern of somatic mutagenesis in the inflamed epithelium of patients with ulcerative colitis. The affected epithelium accumulates somatic mutations in multiple genes that are related to IL-17 signalling-including NFKBIZ, ZC3H12A and PIGR, which are genes that are rarely affected in colon cancer. Targeted sequencing validates the pervasive spread of mutations that are related to IL-17 signalling. Unbiased CRISPR-based knockout screening in colon organoids reveals that the mutations confer resistance to the pro-apoptotic response that is induced by IL-17A. Some of these genetic mutations are known to exacerbate experimental colitis in mice^8-11, and somatic mutagenesis in human colon epithelium may be causally linked to the inflammatory process. Our findings highlight a genetic landscape that adapts to a hostile microenvironment, and demonstrate its potential contribution to the pathogenesis of ulcerative colitis.

Can Nrf2 Modulate the Development of Intestinal Fibrosis and Cancer in Inflammatory Bowel Disease?

One of the main mechanisms carried out by the cells to counteract several forms of stress is the activation of the nuclear factor erythroid 2-related factor (Nrf2) signaling. Nrf2 signaling controls the expression of many genes through the binding of a specific cis-acting element known as the antioxidant response element (ARE). Activation of Nrf2/ARE signaling can mitigate several pathologic mechanisms associated with an autoimmune response, digestive and metabolic disorders, as well as respiratory, cardiovascular, and neurodegenerative diseases. Indeed, several studies have demonstrated that Nrf2 pathway plays a key role in inflammation and in cancer development in many organs, including the intestine. Nrf2 appears to be involved in inflammatory bowel disease (IBD), an immune-mediated chronic and disabling disease, with a high risk of developing intestinal fibrotic strictures and cancer. Currently, drugs able to increase cytoprotective Nrf2 function are in clinical trials or already being used in clinical practice to reduce the progression of some degenerative conditions. The role of Nrf2 in cancer development and progression is controversial, and drugs able to inhibit abnormal levels of Nrf2 are also under investigation. The goal of this review is to analyze and discuss Nrf2-dependent signals in the initiation and progression of intestinal fibrosis and cancers occurring in IBD.

PD123319, angiotensin II type II receptor antagonist, inhibits oxidative stress and inflammation in 2, 4-dinitrobenzene sulfonic acid-induced colitis in rat and ameliorates colonic contractility

Angiotensin II, the main effector of renin angiotensin system, plays an important role in the inflammatory process and most of its effects are mediated through the AT1 receptor activation. However, the knowledge about the AT2 receptor involvement in this process is still evolving. We previously found that in an experimental model of colitis, AT2 receptor activation can contribute to the impairment of the muscle contractility in vitro in the course of inflammation. Here, we investigated the potential alleviating effects of the in vivo treatment of PD123319 (1-[[4-(Dimethylamino)-3-methylphenyl]methyl]-5-(diphenylacetyl)-4,5,6,7- tetrahydro-1H-imidazo[4,5-c]pyridine-6-carboxylic acid ditrifluoroacetate), AT2 receptor antagonist, in 2,4-dinitrobenzene sulfonic acid (DNBS)-induced rat model of colitis. The effects of i.p PD123319 (0.3, 3 and 10 mg/kg) administration to rats subjected to intra-rectal DNBS instillation were investigated. The study revealed that the colon injury and the inflammatory signs were ameliorated by PD123319 when visualized by the histopathological examination. The colon shortening, myeloperoxidase activity, and colonic expression of IL-1β, IL-6 and iNOS were downregulated in a dose-dependent manner in DNBS-induced colitis rats treated with PD123319 and the anti-oxidant defense machinery was also improved. The mechanism of these beneficial effects was found in the ability of PD123319 to inhibit NF-κB activation induced by DNBS. The colonic contractility in inflamed tissues was also improved by PD123319 treatment. In conclusion, our data have demonstrated previously that undescribed proinflammatory effects for the AT2 receptors in DNBS-induced colitis in rats in which they are mediated likely by NF-κB activation and reactive oxygen species generation. Moreover, when the inflammatory process is mitigated by the AT2 receptor antagonist treatment, the smooth muscle is able to recover its functionality.

Elevated Levels of Alveolar Nitric Oxide May Indicate Presence of Small Airway Inflammation in Patients with Inflammatory Bowel Disease

INTRODUCTION

Pulmonary manifestations of inflammatory bowel disease (IBD), albeit not rare, are largely overlooked in clinical practice. The role of exhaled nitric oxide (eNO) as an established biological marker of airway inflammation compels us to use it as a tool to investigate the exact nature of these manifestations.

METHODS

Fractional eNO (FeNO) was measured in multiple flows, and with the use of a mathematical model, alveolar concentration of NO (C_ANO) and bronchial flux of NO (J_awNO) were assessed in 27 patients with IBD [17 with Crohn's disease (CD) and 10 with ulcerative colitis (UC)] and in 39 healthy controls. Carefully selected criteria were used to exclude patients or healthy controls that presented factors considered to be correlated with eNO measurements. Disease activity was measured in Crohn's patients using the CD activity index (CDAI) score and in UC using the partial Mayo score.

RESULTS

C_ANO was significantly higher in the IBD group, compared to the control group (p < 0.0001). FeNO was significantly increased in patients with IBD (p = 0.023), while there was no statistical significance found regarding levels of J_awNO in patients with IBD (p = 0.106), both compared to controls. There was no significant correlation between any eNO component and markers of disease activity.

CONCLUSIONS

Alveolar concentration of NO is elevated in patients with IBD, regardless of disease activity. This may suggest that subclinical small airway inflammation is present in patients with IBD, even those with mild or inactive disease.

Unique Regulation of Enterocyte Brush Border Membrane Na-Glutamine and Na-Alanine Co-Transport by Peroxynitrite during Chronic Intestinal Inflammation

Na-amino acid co-transporters (NaAAcT) are uniquely affected in rabbit intestinal villus cell brush border membrane (BBM) during chronic intestinal inflammation. Specifically, Na-alanine co-transport (ASCT1) is inhibited secondary to a reduction in the affinity of the co-transporter for alanine, whereas Na-glutamine co-transport (B0AT1) is inhibited secondary to a reduction in BBM co-transporter numbers. During chronic intestinal inflammation, there is abundant production of the potent oxidant peroxynitrite (OONO). However, whether OONO mediates the unique alteration in NaAAcT in intestinal epithelial cells during chronic intestinal inflammation is unknown. In this study, ASCT1 and B0AT1 were inhibited by OONO in vitro. The mechanism of inhibition of ASCT1 by OONO was secondary to a reduction in the affinity of the co-transporter for alanine, and secondary to a reduction in the number of co-transporters for B0AT1, which were further confirmed by Western blot analyses. In conclusion, peroxynitrite inhibited both BBM ASCT1 and B0AT1 in intestinal epithelial cells but by different mechanisms. These alterations in the villus cells are similar to those seen in the rabbit model of chronic enteritis. Therefore, this study indicates that peroxynitrite may mediate the inhibition of ASCT1 and B0AT1 during inflammation, when OONO levels are known to be elevated in the mucosa.

Inducible Nitric Oxide Regulates Brush Border Membrane Na-Glucose Co-transport, but Not Na:H Exchange via p38 MAP Kinase in Intestinal Epithelial Cells

During chronic intestinal inflammation in rabbit intestinal villus cells brush border membrane (BBM) Na-glucose co-transport (SGLT1), but not Na/H exchange (NHE3) is inhibited. The mechanism of inhibition is secondary to a decrease in the number of BBM co-transporters. In the chronic enteritis mucosa, inducible nitric oxide (iNO) and superoxide production are known to be increased and together they produce abundant peroxynitrite (OONO), a potent oxidant. However, whether OONO mediates the SGLT1 and NHE3 changes in intestinal epithelial cells during chronic intestinal inflammation is unknown. Thus, we determined the effect of OONO on SGLT1 and NHE3 in small intestinal epithelial cell (IEC-18) monolayers grown on trans well plates. In cells treated with 100 μM SIN-1 (OONO donor) for 24 h, SGLT1 was inhibited while NHE3 activity was unaltered. SIN-1 treated cells produced 40 times more OONO fluorescence compared to control cells. Uric acid (1mM) a natural scavenger of OONO prevented the OONO mediated SGLT1 inhibition. Na⁺/K⁺-ATPase which maintains the favorable trans-cellular Na gradient for Na-dependent absorptive processes was decreased by OONO. Kinetics studies demonstrated that the mechanism of inhibition of SGLT1 by OONO was secondary to reduction in the number of co-transporters (V_max) without an alteration in the affinity. Western blot analysis showed a significant decrease in SGLT1 protein expression. Further, p38 mitogen-activated protein (MAP) kinase pathway appeared to mediate the OONO inhibition of SGLT1. Finally, at the level of the co-transporter, 3-Nitrotyrosine formation appears to be the mechanism of inhibition of SGLT1. In conclusion, peroxynitrite inhibited BBM SGLT1, but not NHE3 in intestinal epithelial cells. These changes and the mechanism of SGLT1 inhibition by OONO in IEC-18 cells is identical to that seen in villus cells during chronic enteritis. Thus, these data indicate that peroxynitrite, known to be elevated in the mucosa, may mediate the inhibition of villus cell BBM SGLT1 in vivo in the chronically inflamed intestine.

A probabilistic pathway score (PROPS) for classification with applications to inflammatory bowel disease

Summary

Gene-based supervised machine learning classification models have been widely used to differentiate disease states, predict disease progression and determine effective treatment options. However, many of these classifiers are sensitive to noise and frequently do not replicate in external validation sets. For complex, heterogeneous diseases, these classifiers are further limited by being unable to capture varying combinations of genes that lead to the same phenotype. Pathway-based classification can overcome these challenges by using robust, aggregate features to represent biological mechanisms. In this work, we developed a novel pathway-based approach, PRObabilistic Pathway Score, which uses genes to calculate individualized pathway scores for classification. Unlike previous individualized pathway-based classification methods that use gene sets, we incorporate gene interactions using probabilistic graphical models to more accurately represent the underlying biology and achieve better performance. We apply our method to differentiate two similar complex diseases, ulcerative colitis (UC) and Crohn's disease (CD), which are the two main types of inflammatory bowel disease (IBD). Using five IBD datasets, we compare our method against four gene-based and four alternative pathway-based classifiers in distinguishing CD from UC. We demonstrate superior classification performance and provide biological insight into the top pathways separating CD from UC.

Availability and Implementation

PROPS is available as a R package, which can be downloaded at http://simtk.org/home/props or on Bioconductor.

Contact

rbaltman@stanford.edu.

Supplementary information

Supplementary data are available at Bioinformatics online.

The Anti-Inflammatory Effect and Structure of EPCP1-2 from Crypthecodinium cohnii via Modulation of TLR4-NF-κB Pathways in LPS-Induced RAW 264.7 Cells

Exopolysaccharide from Crypthecodinium cohnii (EPCP1-2) is a marine exopolysaccharide that evidences a variety of biological activities. We isolated a neutral polysaccharide from the fermentation liquid of Crypthecodinium cohnii (CP). In this study, a polysaccharide that is derived from Crypthecodinium cohnii were analyzed and its anti-inflammatory effect was evaluated on protein expression of toll-like receptor 4 and nuclear factor κB pathways in macrophages. The structural characteristics of EPCP1-2 were characterized by GC (gas chromatography) and GC-MS (gas Chromatography-Mass Spectrometer) analyses. The molecular weight was about 82.5 kDa. The main chain of EPCP1-2 consisted of (1→6)-linked mannopyranosyl, (1→6)-linked glucopyranosyl, branched-chain consisted of (1→3,6)-linked galactopyranosyl and terminal consisted of t-l-Rhapyranosyl. The in vitro anti-inflammatory activity was representated through assay of proliferation rate, pro-inflammatory factor (NO) and expressions of proteins on RAW 264.7, the macrophage cell line. The results revealed that EPCP1-2 exhibited significant anti-inflammatory activity by regulating the expression of toll-like receptor 4, mitogen-activated protein kinases, and Nuclear Factor-κB protein.

Elevation of GPRC5A expression in colorectal cancer promotes tumor progression through VNN-1 induced oxidative stress

The clearance of oxidative stress compounds is critical for the protection of the organism from malignancy, but how this key physiological process is regulated is not fully understood. Here, we found that the expression of GPRC5A, a well-characterized tumor suppressor in lung cancer, was elevated in colorectal cancer tissues in patients. In both cancer cell lines and a colitis-associated cancer model in mice, we found that GPRC5A deficiency reduced cell proliferation and increased cell apoptosis as well as inhibited tumorigenesis in vivo. Through RNA-Seq transcriptome analysis, we identified oxidative stress associated pathways were dysregulated. Moreover, in GPRC5A deficient cells and mouse tissues, the oxidative agents were reduced partially due to increased glutathione (GSH) level. Mechanistically, GPRC5A regulates NF-κB mediated Vanin-1 expression which is the predominant enzyme for cysteamine generation. Administration of cystamine (the disulfide form of cysteamine) in GPRC5A deficient cell lines inhibited γ-GCS activity, leading to reduction of GSH level and increase of cell growth. Taken together, our studies suggest that GPRC5a is a potential biomarker for colon cancer and promotes tumorigenesis through stimulation of Vanin-1 expression and oxidative stress in colitis associated cancer. This study revealed an unexpected oncogenic role of GPRC5A in colorectal cancer suggesting there are complicated functional and molecular mechanism differences of this gene in distinct tissues.

5-Aminosalicylic acid inhibits inflammatory responses by suppressing JNK and p38 activity in murine macrophages

CONTEXT

5-Aminosalicylic acid (5-ASA), as an anti-inflammatory drug, has been extensively used for the treatment of mild to moderate active ulcerative colitis (UC), but the possible mechanisms of action remain unclear.

OBJECTIVE

To investigate the effects of 5-ASA on the production of inflammatory mediators by murine macrophages stimulated with lipopolysaccharide (LPS), and determine the underlying pharmacological mechanism of action.

MATERIALS AND METHODS

The levels of nitric oxide (NO) and interleukin-6 (IL-6) were measured by Varioskan Flash and IL-6 Enzyme-Linked Immunosorbent Assay sets. Real time quantitative polymerase chain reaction was used to determine the level of induced nitric oxide synthase (iNOS). The effects of 5-ASA on iNOS, the c-Jun N-terminal kinases (JNKs), p38 and nuclear factor (NF)-κB signaling pathways were examined using western blotting.

RESULTS

5-ASA suppressed the production of NO and IL-6, and also decreased the expression of iNOS in LPS-induced RAW264.7 cells. 5-ASA inhibited the phosphorylation of JNKs and p38, but did not block NF-κB activation at all doses tested.

DISCUSSION AND CONCLUSION

The results indicated that the anti-inflammatory effect of 5-ASA was mainly regulated by the inhibition of the JNKs, p38 pathways rather than NF-κB pathway. Further research is required to clarify the detailed mechanism of the action.

Morinda citrifolia (Noni) Fruit Juice Reduces Inflammatory Cytokines Expression and Contributes to the Maintenance of Intestinal Mucosal Integrity in DSS Experimental Colitis

Morinda citrifolia L. (noni) has been shown to treat different disorders. However, data concerning its role in the treatment of intestinal inflammation still require clarification. In the current study, we investigated the effects of noni fruit juice (NFJ) in the treatment of C57BL/6 mice, which were continuously exposed to dextran sulfate sodium (DSS) for 9 consecutive days. NFJ consumption had no impact on the reduction of the clinical signs of the disease or on weight loss. Nonetheless, when a dilution of 1 : 10 was used, the intestinal architecture of the mice was preserved, accompanied by a reduction in the inflammatory infiltrate. Regardless of the concentration of NFJ, a decrease in both the activity of myeloperoxidase and the key inflammatory cytokines, TNF-α and IFN-γ, was also observed in the intestine. Furthermore, when NFJ was diluted 1 : 10 and 1 : 100, a reduction in the production of nitric oxide and IL-17 was detected in gut homogenates. Overall, the treatment with NFJ was effective in different aspects associated with disease progression and worsening. These results may point to noni fruit as an important source of anti-inflammatory molecules with a great potential to inhibit the progression of inflammatory diseases, such as inflammatory bowel disease.

Deoxyschizandrin suppresses dss-induced ulcerative colitis in mice

BACKGROUND/AIMS

Deoxyschizandrin as one of the most important component of Schisandra chinensis (Turcz.) Baill plays an immunomodulatory role in a variety of diseases, yet its role in ulcerative colitis remains to be elucidated. We aimed to investigate the role of deoxyschizandrin in DSS-induced ulcerative colitis in mice.

PATIENTS AND METHODS

In the present study, an inflammation model of cells was constructed to confirm the anti-inflammatory effect of deoxyschizandrin. Then a mouse model with Dextran sulfate sodium sulfate (DSS)-induced ulcerative colitis was constructed, and the effects of deoxyschizandrin on mouse colon inflammation, apoptosis, and CD4 T lymphocyte infiltration in ulcerative colitis were examined.

RESULT

Deoxyschizandrin could improve the symptoms of ulcerative colitis, determined by hematoxylin-eosin (HE) staining and histopathological scores. Moreover, deoxyschizandrin reduced the levels of inflammatory cytokines, suppressed CD4 T cell infiltration, and effectively inhibited apoptosis in the colon of DSS-induced ulcerative colitis mice.

CONCLUSION

In summary, deoxyschizandrin can effectively rescue the symptoms of DSS-induced ulcerative colitis in mice by inhibiting inflammation. T cell infiltration and apoptosis in the colon, suggesting that deoxyschizandrin could be a potential drug in treating ulcerative colitis.

Impact of DNA repair on the dose-response of colorectal cancer formation induced by dietary carcinogens

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers, which is causally linked to dietary habits, notably the intake of processed and red meat. Processed and red meat contain dietary carcinogens, including heterocyclic aromatic amines (HCAs) and N-nitroso compounds (NOC). NOC are agents that induce various N-methylated DNA adducts and O⁶-methylguanine (O⁶-MeG), which are removed by base excision repair (BER) and O⁶-methylguanine-DNA methyltransferase (MGMT), respectively. HCAs such as the highly mutagenic 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) cause bulky DNA adducts, which are removed from DNA by nucleotide excision repair (NER). Both O⁶-MeG and HCA-induced DNA adducts are linked to the occurrence of KRAS and APC mutations in colorectal tumors of rodents and humans, thereby driving CRC initiation and progression. In this review, we focus on DNA repair pathways removing DNA lesions induced by NOC and HCA and assess their role in protecting against mutagenicity and carcinogenicity in the large intestine. We further discuss the impact of DNA repair on the dose-response relationship in colorectal carcinogenesis in view of recent studies, demonstrating the existence of 'no effect' point of departures (PoDs), i.e. thresholds for genotoxicity and carcinogenicity. The available data support the threshold concept for NOC with DNA repair being causally involved.

Invasion by Trichinella spiralis infective larvae affects the levels of inflammatory cytokines in intestinal epithelial cells in vitro

As we all know, invasion of host intestinal epithelium is very important for T. spiralis to complete successfully their life cycle. However, the mechanisms that the intestinal infective larvae (IIL) invade and migrate in the intestinal epithailial cells (IECs) remain unclear until now. The related researches have been hindered since a readily operable in vitro normal model. In our earlier study, an in vitro normal IEC invasion model was established for the first time, and the abilities of the normal IECs to initiate mucosal inflammatory responses to invasion by the IIL in vitro were evaluated in this study. When the IIL were overlaid on the normal mouse IEC monolayers, they quickly within seconds invaded the monolayers and move within the IECs, leaving trails of damaged cells. Then the larvae were found to have started their molting at 12 h, and the complete cuticle was found at 24 h. The percentage of the first molt in the larvae was about 62.3%, and the percentage of the 2nd-4th molt was about 38.2% at 36 h. Real-time PCR showed that the mRNA levels of interleukin-1β (IL-1β), IL-8, epithelial neutrophil-activating peptide 78 (ENA-78), inducible nitric oxide synthase (iNOS), and monocyte chemotactic protein 2 (MCP-2) were elevated in the IECs after 7 h of infection after invasion by the IIL, and their levels were enhanced with the increase of larvae number. No changes in tumor necrosis factor-α (TNF-α) mRNA were observed after the IIL invasion. Secretion increases of IL-1β and IL-8 from the IEC monolayers invaded by T. spiralis were also detected by ELISA. Secretion increases of proinflammatory cytokines and inflammatory mediators in normal IECs can launch the acute inflammatory in response to the IIL invasion. This study would be helpful in further investigating the relationship between the host and T. spiralis, and the immune escape mechanisms of the niche established by T. spiralis.

Overview of cytokines and nitric oxide involvement in immuno-pathogenesis of inflammatory bowel diseases

Inflammatory bowel diseases (IBDs), including Crohn’s disease and ulcerative colitis are complex disorders with undetermined etiology. Several hypotheses suggest that IBDs result from an abnormal immune response against endogenous flora and luminal antigens in genetically susceptible individuals. The dysfunction of the mucosal immune response is implicated in the pathogenesis of IBD. The balance between pro-inflammatory cytokines [tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-8, and IL-17A], anti-inflammatory cytokines (IL-4 and IL-13), and immunoregulatory cytokines (IL-10 and transforming growth factors β) is disturbed. Moreover, evidence from animal and clinical studies demonstrate a positive correlation between an increased concentration of nitric oxide (NO) and the severity of the disease. Interestingly, proinflammatory cytokines are involved in the up-regulation of inducible oxide synthase (iNOS) expression in IBD. However, anti-inflammatory and immunoregulatory cytokines are responsible for the negative regulation of iNOS. A positive correlation between NO production and increased pro-inflammatory cytokine levels (TNF-α, IL-6, IL-17, IL-12, and interferon-γ) were reported in patients with IBD. This review focuses on the role of cytokines in intestinal inflammation and their relationship with NO in IBD.

Antioxidant and Anti-Inflammatory Effects of Chaenomeles sinensis Leaf Extracts on LPS-Stimulated RAW 264.7 Cells

The fruit of Chaenomeles sinensis has been traditionally used in ethnomedicine for the treatment of various human ailments, including pneumonia, bronchitis, and so on, but the pharmacological applications of the leaf part of the plant have not been studied. In this study, we evaluated the various radical scavenging activities and anti-inflammatory effects of different Chaenomeles sinensis leaf (CSL) extracts. The water extract showed a higher antioxidant and radical scavenging activities. However the ethanolic extracts showed higher NO scavenging activity than water extract, therefore the ethanolic extract of CSL was examined for anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. The 70% ethanol extract of CSL (CSLE) has higher anti-inflammatory activity and significantly inhibited the production of nitric oxide (NO), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). In addition, CSLE suppressed LPS-stimulated inducible nitric oxide synthase (iNOS) and NO production, IL-1β and phospho-STAT1 expression. In this study, we investigated the effect of CSLE on the production of inflammatory mediators through the inhibition of the TRIF-dependent pathways. Furthermore, we evaluated the role of CSLE on LPS-induced expression of pro-inflammatory cytokines, such as TNF-α, IL-1β and IL-6. Our results suggest that CSLE attenuates the LPS-stimulated inflammatory responses in macrophages through regulating the key inflammatory mechanisms, providing scientific support for its traditional uses in treating various inflammatory diseases.

Prenylated Flavonoids from Cudrania tricuspidata Suppress Lipopolysaccharide-Induced Neuroinflammatory Activities in BV2 Microglial Cells

In Korea and China, Cudrania tricuspidata Bureau (Moraceae) is an important traditional medicinal plant used to treat lumbago, hemoptysis, and contusions. The C. tricuspidata methanol extract suppressed both production of NO and PGE₂ in BV2 microglial cells. Cudraflavanone D (1), isolated from this extract, remarkably suppressed the protein expression of inducible NO synthase and cyclooxygenase-2, and decreased the levels of NO and PGE₂ in BV2 microglial cells exposed to lipopolysaccharide. Cudraflavanone D (1) also decreased IL-6, TNF-α, IL-12, and IL-1β production, blocked nuclear translocation of NF-κB heterodimers (p50 and p65) by interrupting the degradation and phosphorylation of inhibitor of IκB-α, and inhibited NF-κB binding. In addition, cudraflavanone D (1) suppressed the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 MAPK pathways. This study indicated that cudraflavanone D (1) can be a potential drug candidate for the cure of neuroinflammation.

The implications of oxidative stress and antioxidant therapies in Inflammatory Bowel Disease: Clinical aspects and animal models

Inflammatory bowel disease (IBD), including Crohn's disease (CD) and ulcerative colitis (UC), is a chronic inflammatory disorder characterized by alternating phases of clinical relapse and remission. The etiology of IBD remains largely unknown, although a combination of patient's immune response, genetics, microbiome, and environment plays an important role in disturbing intestinal homeostasis, leading to development and perpetuation of the inflammatory cascade in IBD. As chronic intestinal inflammation is associated with the formation of reactive oxygen and reactive nitrogen species (ROS and RNS), oxidative and nitrosative stress has been proposed as one of the major contributing factor in the IBD development. Substantial evidence suggests that IBD is associated with an imbalance between increased ROS and decreased antioxidant activity, which may explain, at least in part, many of the clinical pathophysiological features of both CD and UC patients. Hereby, we review the presently known oxidant and antioxidant mechanisms involved in IBD-specific events, the animal models used to determine these specific features, and also the antioxidant therapies proposed in IBD patients.

Altered cGMP dynamics at the plasma membrane contribute to diarrhea in ulcerative colitis

Ulcerative colitis (UC) belongs to inflammatory bowel disorders, a group of gastrointestinal disorders that can produce serious recurring diarrhea in affected patients. The mechanism for UC- and inflammatory bowel disorder-associated diarrhea is not well understood. The cystic fibrosis transmembrane-conductance regulator (CFTR) chloride channel plays an important role in fluid and water transport across the intestinal mucosa. CFTR channel function is regulated in a compartmentalized manner through the formation of CFTR-containing macromolecular complexes at the plasma membrane. In this study, we demonstrate the involvement of a novel macromolecular signaling pathway that causes diarrhea in UC. We found that a nitric oxide-producing enzyme, inducible nitric oxide synthase (iNOS), is overexpressed under the plasma membrane and generates compartmentalized cGMP in gut epithelia in UC. The scaffolding protein Na(+)/H(+) exchanger regulatory factor 2 (NHERF2) bridges iNOS with CFTR, forming CFTR-NHERF2-iNOS macromolecular complexes that potentiate CFTR channel function via the nitric oxide-cGMP pathway under inflammatory conditions both in vitro and in vivo. Potential disruption of these complexes in Nherf2(-/-) mice may render them more resistant to CFTR-mediated secretory diarrhea than Nherf2(+/+) mice in murine colitis models. Our study provides insight into the mechanism of pathophysiologic occurrence of diarrhea in UC and suggests that targeting CFTR and CFTR-containing macromolecular complexes will ameliorate diarrheal symptoms and improve conditions associated with inflammatory bowel disorders.

Microangiopathy triggers, and inducible nitric oxide synthase exacerbates dextran sulfate sodium-induced colitis

Ulcerative colitis (UC) is a representative clinical manifestation of inflammatory bowel disease that causes chronic gastrointestinal tract inflammation. Dextran sulfate sodium (DSS)-induced colitis mice have been used to investigate UC pathogenesis, and in this UC model, disturbance and impairment of the mucosal epithelium have been reported to cause colitis. However, how DSS sporadically breaks down the epithelium remains unclear. In this study, we focused on the colonic microcirculation and myenteric neurons of DSS-induced colitis. Moreover, we examined the potential of myenteric neurons as a target to prevent exacerbation of colitis. Fluorescent angiographic and histopathological studies revealed that DSS administration elicited blood vessel disruption before epithelial disorders appeared. Ischemic conditions in the lamina propria induced inducible nitric oxide synthase (iNOS) expression in myenteric neurons as colitis aggravated. When neuronal activity was inhibited with butylscopolamine, neuronal iNOS expression decreased, and the exacerbation of colitis was prevented. These results suggested that DSS-induced colitis was triggered by microcirculatory disturbance in the mucosa, and that excessive neuronal excitation aggravated colitis. During remission periods of human UC, endoscopic inspection of the colonic microcirculation may enable the early detection of disease recurrence, and inhibition of neuronal iNOS expression may prevent the disease from worsening.

High nitric oxide production, secondary to inducible nitric oxide synthase expression, is essential for regulation of the tumour-initiating properties of colon cancer stem cells

Chronic inflammation is a leading cause of neoplastic transformation in many human cancers and especially in colon cancer (CC), in part due to tumour promotion by nitric oxide (NO) generated at inflammatory sites. It has also been suggested that high NO synthesis, secondary to inducible NO synthase (iNOS) expression, is a distinctive feature of cancer stem cells (CSCs), a small subset of tumour cells with self-renewal capacity. In this study we explored the contribution of NO to the development of colon CSC features and evaluated potential strategies to treat CC by modulating NO production. Our data show an integral role for endogenous NO and iNOS activity in the biology of colon CSCs. Indeed, colon CSCs with high endogenous NO production (NO(high)) displayed higher tumourigenic abilities than NO(low) fractions. The blockade of endogenous NO availability, using either a specific iNOS inhibitor or a genetic knock-down of iNOS, resulted in a significant reduction of colon CSC tumourigenic capacities in vitro and in vivo. Interestingly, analysis of genes altered by iNOS-directed shRNA showed that the knockdown of iNOS expression was associated with a significant down-regulation of signalling pathways involved in stemness and tumour progression in colon CSCs. These findings confirm that endogenous NO plays an important role in defining the stemness properties of colon CSCs through cross-regulation of several cellular signalling pathways. This discovery could shed light on the mechanisms by which NO induces the growth and invasiveness of CC, providing new insights into the link between inflammation and colon tumourigenesis.

A novel synthetic derivative of melatonin, 5-hydroxy-2'-isobutyl-streptochlorin (HIS), inhibits inflammatory responses via regulation of TRIF-dependent signaling and inflammasome activation

Melatonin is substantially reported to possess anti-inflammatory properties. In the present study, we synthesized a novel melatonin derivative, 5-hydroxy-2'-isobutyl-streptochlorin (HIS), which displayed superior anti-inflammatory properties to its parent compound. Further, we explored its underlying mechanisms in cellular and experimental animal models. Lipopolysaccharide was used to induce in vitro inflammatory responses in RAW 264.7 macrophages. LPS-primed macrophages were pulsed with biologically unrelated toxic molecules to evaluate the role of HIS on inflammasome activation. In vivo verifications were carried out using acute lung injury (ALI) and Escherichia coli-induced septic shock mouse models. HIS inhibited the production of proinflammatory mediators and cytokines such as nitric oxide, cyclooxygenase 2, IL-1β, IL-6 and TNF-α in LPS-stimulated RAW 264.7 macrophages. HIS suppressed the infiltration of immune cells into the lung and the production of pro-inflammatory cytokines such as IL-6 and TNF-α in broncho-alveolar lavage fluid in the ALI mouse model. Mechanistic studies revealed that the inhibitory effects of HIS were mediated through the regulation of the TIR domain-containing, adaptor-inducing, interferon-β (TRIF)-dependent signaling pathway from toll-like receptors. Further, HIS attenuated IL-1β secretion via the inhibition of NLRP3 inflammasome activation independent of mitochondrial ROS production. Furthermore, HIS suppressed IL-1β, IL-6 and interferon-β production in peritoneal lavage in the Escherichia coli-induced sepsis mouse model. In conclusion, HIS exerted potent anti-inflammatory effects via the regulation of TRIF-dependent signaling and inflammasome activation. Notably, the superior anti-inflammatory properties of this derivative compared with its parent compound could be a promising lead for treating various inflammatory-mediated diseases.

Interactions of flavan-3-ols and procyanidins with membranes: mechanisms and the physiological relevance

Flavonoids are a type of phenolic compound widely present in edible plants. A great number of health benefits have been ascribed to flavonoid consumption in the human population. However, the molecular mechanisms involved in such effects remain to be identified. The flavan-3-ols (-)-epicatechin and (+)-catechin, and their related oligomers (procyanidins) have been thoroughly studied because of their capacity to interact with cell membranes. Starting with these interactions, procyanidins could modulate multiple biochemical processes, such as enzyme activities, receptor-ligand binding, membrane-initiated cell signaling, and molecule transport across membranes. This review focuses on molecular aspects of procyanidin interactions with membrane lipid components, and the resulting protection of the membranes against mechanical and/or oxidative damage, resulting in the maintenance of cell functions.

Lysimachia clethroides Duby extract attenuates inflammatory response in Raw 264.7 macrophages stimulated with lipopolysaccharide and in acute lung injury mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Lysimachia clethroides Duby (LC) is a traditional medicinal herb used to treat edema, hepatitis and inflammatory diseases in China and other Asian countries. In this study, the anti-inflammatory effects of LC extract and the mechanisms underlying were explored in both in vitro cell lines and acute lung injury (ALI) animal model of inflammation in vivo.

MATERIALS AND METHODS

Lipopolysaccharide (LPS)-stimulated Raw 264.7 murine macrophages were used to study the regulatory effects of LC extract on inflammatory mediators such as nitric oxide (NO) and proinflammatory cytokine expression. Western blotting or ELISA techniques were employed to estimate protein levels. RT-PCR was used for analyzing the interferon (IFN)-β production. LPS-induced ALI mouse model in vivo was employed to study the effect of LC extract. Further high-performance liquid chromatography (HPLC) fingerprinting technique was used to evaluate the active constituents present in LC extract, compared with reference standards.

RESULTS

Pre-treatment with LC extract inhibited the LPS-stimulated NO release, interleukin (IL)-1β and IL-6 production in Raw 264.7 cells dose dependently. LC extract inhibited the LPS-stimulated IRF3 and STAT1 phosphorylation. Further, in vivo experiments revealed that LC extract suppressed the infiltration of immune cells into the lung and proinflammatory cytokine production in broncho-alveolar lavage fluid (BALF) in the LPS-induced ALI mouse model.

CONCLUSIONS

Our results indicate that LC extract attenuates LPS-stimulated inflammatory responses in macrophages via regulating the key inflammatory mechanisms, providing a scientific support for its traditional use in treating various inflammatory diseases.

Chemistry meets biology in colitis-associated carcinogenesis

The intestine comprises an exceptional venue for a dynamic and complex interplay of numerous chemical and biological processes. Here, multiple chemical and biological systems, including the intestinal tissue itself, its associated immune system, the gut microbiota, xenobiotics, and metabolites meet and interact to form a sophisticated and tightly regulated state of tissue homoeostasis. Disturbance of this homeostasis can cause inflammatory bowel disease (IBD)-a chronic disease of multifactorial etiology that is strongly associated with increased risk for cancer development. This review addresses recent developments in research into chemical and biological mechanisms underlying the etiology of inflammation-induced colon cancer. Beginning with a general overview of reactive chemical species generated during colonic inflammation, the mechanistic interplay between chemical and biological mediators of inflammation, the role of genetic toxicology, and microbial pathogenesis in disease development are discussed. When possible, we systematically compare evidence from studies utilizing human IBD patients with experimental investigations in mice. The comparison reveals that many strong pathological and mechanistic correlates exist between mouse models of colitis-associated cancer, and the clinically relevant situation in humans. We also summarize several emerging issues in the field, such as the carcinogenic potential of novel inflammation-related DNA adducts and genotoxic microbial factors, the systemic dimension of inflammation-induced genotoxicity, and the complex role of genome maintenance mechanisms during these processes. Taken together, current evidence points to the induction of genetic and epigenetic alterations by chemical and biological inflammatory stimuli ultimately leading to cancer formation.

Anti-inflammatory effect of neoechinulin a from the marine fungus Eurotium sp. SF-5989 through the suppression of NF-кB and p38 MAPK Pathways in lipopolysaccharide-stimulated RAW264.7 macrophages

In the course of a bioassay-guided study of metabolites from the marine fungus Eurotium sp. SF-5989, two diketopiperazine type indole alkaloids, neoechinulins A and B, were isolated. In this study, we investigated the anti-inflammatory effects of neoechinulins A (1) and B (2) on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Neoechinulin A (1) markedly suppressed the production of nitric oxide (NO) and prostaglandin E₂ (PGE₂) and the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose dependent manner ranging from 12.5 µM to 100 µM without affecting the cell viability. On the other hand, neoechinulin B (2) affected the cell viability at 25 µM although the compound displayed similar inhibitory effect of NO production to neoechinulin A (1) at lower doses. Furthermore, neoechinulin A (1) decreased the secretion of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). We also confirmed that neoechinulin A (1) blocked the activation of nuclear factor-kappaB (NF-κB) in LPS-stimulated RAW264.7 macrophages by inhibiting the phosphorylation and degradation of inhibitor kappa B (IκB)-α. Moreover, neoechinulin A (1) decreased p38 mitogen-activated protein kinase (MAPK) phosphorylation. Therefore, these data showed that the anti-inflammatory effects of neoechinulin A (1) in LPS-stimulated RAW264.7 macrophages were due to the inhibition of the NF-κB and p38 MAPK pathways, suggesting that neoechinulin A (1) might be a potential therapeutic agent for the treatment of various inflammatory diseases.

The inhibition of JNK MAPK and NF-κB signaling by tenuifoliside A isolated from Polygala tenuifolia in lipopolysaccharide-induced macrophages is associated with its anti-inflammatory effect

The root of Polygala tenuifolia Willd. (Polygalaceae) is well known for its use in the treatment of neurasthenia, amnesia, and inflammation. In this study, we isolated phenyl propanoid type metabolite tenuifoliside A, one of the phenylpropanoids from P. tenuifolia, and investigated its anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated RAW264.7 and murine peritoneal macrophages. The results showed that tenuifoliside A inhibited the production of nitric oxide (NO), inducible nitric oxide synthase (iNOS), prostaglandin E2 (PG E2), and cyclooxygenase (COX)-2. In addition, tenuifoliside A suppressed the production of pro-inflammatory cytokines, such as tumor necrosis factor (TNF)-α and interleukin (IL)-1β. We also evaluated the effects of tenuifoliside A on the activation of nuclear factor-kappaB (NF-κB). Tenuifoliside A inhibited the translocation of the NF-κB subunit p65 into the nucleus by interrupting the phosphorylation and degradation of inhibitor kappa B (IκB)-α in LPS-stimulated murine peritoneal macrophages. Moreover, we confirmed that the suppression of the inflammatory process by tenuifoliside A was mediated through the mitogen-activated protein kinases (MAPKs) pathway based on the fact that tenuifoliside A significantly decreased p-c-Jun N-terminal kinase (p-JNK) protein expression in LPS-stimulated murine peritoneal macrophages. Taken together, the anti-inflammatory effects of tenuifoliside A were mediated by the inhibition of the NF-κB and MAPK pathways. This study is the first report on the anti-inflammatory effects of tenuifoliside A, and the strong anti-inflammatory effects of tenuifoliside A provide potential compound to be developed as therapeutic for inflammatory diseases.

O6-methylguanine-DNA methyltransferase in the defense against N-nitroso compounds and colorectal cancer

Colorectal cancer (CRC) is among the leading causes of cancer death worldwide, involving multiple dietary and non-dietary risk factors. A growing body of evidence suggests that N-nitroso compounds (NOC) play a pivotal role in the etiology of CRC. NOC are present in food and are also formed endogenously in the large intestine. Upon metabolic activation and also spontaneously, they form electrophilic species that methylate the DNA, producing N-methylated purines and O(6)-methylguanine, the latter of which bears high mutagenic and carcinogenic potential. Methylated DNA bases are removed by base excision repair initiated by the alkyladenine-DNA glycosylase, the family of AlkB homologs proteins, and the suicide enzyme O(6)-methylguanine-DNA methyltransferase (MGMT), which is the main focus of this review. We present animal models with a deficiency of MGMT that display a tremendously enhanced sensitivity toward alkylation-induced colorectal carcinogenesis, highlighting its role in the protection against the cytotoxic and mutagenic effects of alkylating agents. In line with these studies, MGMT was linked to the formation of human sporadic CRC. Colorectal tumors and precursor lesions frequently display epigenetic inactivation of MGMT resulting from promoter hypermethylation, which is tightly associated with the occurrence of G:C to A:T transition mutations in the KRAS oncogene. We also discuss clinical data, which identified the MGMT status of CRC patients as promising parameter for the treatment of metastasized CRC using alkylating anticancer drugs such as temozolomide.

Oral administration of the flavonoid myricitrin prevents dextran sulfate sodium-induced experimental colitis in mice through modulation of PI3K/Akt signaling pathway

SCOPE

We investigated the protective effect of the flavonoid myricitrin in dextran sulfate sodium (DSS) induced colitis as promising candidate for the treatment of ulcerative colitis which is considered an important worldwide public health problem.

METHODS AND RESULTS

Male CD1 mice were provided with a solution of filtered water containing 3% w/v DSS ad libitum over a 5-day period followed by 2 days with normal drinking water. Myricitrin was administered orally, once a day, at the doses 1, 3, and 10 mg/kg of body weight. At the end of day 7th, the animals were euthanized and the colonic tissue was collected to be analyzed by RT-PCR, immunohistochemistry and Western blot. Our results showed that oral treatment with myricitrin exerts consistent anti-inflammatory action in DSS-induced acute colitis in mice by the inhibition of the Akt/phosphatidylinositol-3 kinase-dependent phosphorylation. Consequently, the phosphorylation of mitogen-activated protein kinases (MAPK) p38, extracellular signal-regulated protein kinase (ERK1/2), and c-Jun N-terminal kinase and of the nuclear factor B (NF-κB) was reduced and prevented an increase in the cytokines/chemokines levels.

CONCLUSION

Together, these data reveal that the anti-inflammatory effect of myricitrin in DSS-induced colitis in mice is likely associated with its ability to prevent the activation of upstream kinases, such as phosphatidylinositol-3 kinase-dependent Akt, NF-κB, and mitogen-activated protein kinase.

Elevated incidence of polyp formation in APC(Min/⁺)Msh2⁻/⁻ mice is independent of nitric oxide-induced DNA mutations

Gut microbiota has been linked to a number of human diseases including colon cancer. However, the mechanism through which gut bacteria influence colon cancer development and progression remains unclear. Perturbation of the homeostasis between the host immune system and microbiota leads to inflammation and activation of macrophages which produce large amounts of nitric oxide that acts as a genotoxic effector molecule to suppress bacterial growth. However, nitric oxide also has genotoxic effects to host cells by producing mutations that can predispose to colon cancer development. The major DNA lesions caused by nitric oxide are 8oxoG and deamination of deoxycytosine bases. Cellular glycosylases that belong to the base excision repair pathway have been demonstrated to repair these mutations. Recent evidence suggests that the mismatch repair pathway (MMR) might also repair nitric oxide-induced DNA damage. Since deficiency in MMR predisposes to colon cancer, we hypothesized that MMR-deficient colon epithelial cells are incapable of repairing nitric-oxide induced genetic lesions that can promote colon cancer. Indeed, we found that the MMR pathway repairs nitric oxide-induced DNA mutations in cell lines. To test whether nitric oxide promotes colon cancer, we genetically ablated the inducible nitric oxide synthase (iNOS) or inhibited iNOS activity in the APC(Min/+)Msh2(-/-) mouse model of colon cancer. However, despite the fact that nitric oxide production was strongly reduced in the colon using both approaches, colon cancer incidence was not affected. These data show that nitric oxide and iNOS do not promote colon cancer in APC(Min/+)Msh2(-/-) mice.

The expression of iNOS and nitrotyrosine in colitis and colon cancer in humans

Chronic inflammation increases the risk of development of several types of malignancies including colon cancer. It also represents a paradigm for the connection between inflammation and cancer in terms of epidemiology and mechanistic studies in preclinical models. A key component of inflammation promoting cancer is the transcription factor NF-κB, which is known to play a critical role in the regulation of the inducible nitric oxide synthase (iNOS) gene. iNOS is an enzyme dominantly expressed during inflammatory reactions. Although synthesis of high amounts of nitric oxide (NO) by iNOS has been demonstrated in pathophysiological processes, such as acute or chronic inflammation and tumorigenesis, the role of iNOS activity in these diseases is still not well understood. Analysis of human biopsies of colitis and colon cancer using immunohistochemistry revealed elevated iNOS protein expression levels, which were strongly paralleled by increased expression of nitrotyrosine suggesting that iNOS has been highly activated in these tissues. These results were corroborated in an in vitro study showing the presence of high iNOS levels in a colon cancer cell line (HT-29) following inflammatory stimuli (TNF-α, peroxynitrite). In addition, the involvement of metastatic processes in the colon biopsies was assessed by means of in situ zymography of MMP activation. MMP 2 (gelatinase A) activation was higher in histopathological sections of colitis and cancer compared to controls. Overall, these data strengthen the findings that in inflammation and colon cancer in humans, iNOS expression and tyrosine nitration may be an indicator of cancer development and progression.