Protective role of heme oxygenase-1 on trinitrobenzene sulfonic acid-induced colitis in rats

NFE2L3 regulates inflammation and oxidative stress-related genes in the colon

The molecular mechanisms leading to inflammatory bowel disease (IBD) are only partially understood. We investigated the role of the transcription factor NFE2L3 in a mouse model of colitis by inducing inflammation using dextran sodium sulfate (DSS). We confirmed the presence of inflammation by histological analysis and elevated levels of the inflammation marker lipocalin-2 (LCN2) in the stool. We found that Lcn2 transcript levels are significantly less elevated in Nfe2l3-/- mice than wild type mice. We further showed a reduction of Nfe2l3 mRNA, in wildtype mice upon DSS treatment. We cross referenced ENCODE ChIP data of NFE2L3 binding partners MAFF and MAFK with known IBD and DSS effectors and identified Stat1, Hmox1, and Slc7a11 as potential NFE2L3 targets. These proteins are induced during colitis to suppress the immune response, reduce oxidative stress, and trigger ferroptosis, respectively. We analyzed the candidate targets and observed an increase in their protein expression upon DSS treatment in wild type but not in Nfe2l3-/- mice. Furthermore, in the absence of DSS, we observed an increase in the basal levels of pSTAT1 and SLC7A11 proteins in Nfe2l3-/- mice. These data suggest that the NFE2L3 transcription factor primes the microenvironment towards a pro-inflammatory ready state during inflammatory bowel disease (IBD).

Carbon monoxide produced by HO-1 upregulation is the main factor behind the abnormal motility seen in experimental ulcerative colitis in mice

The colonic motility is altered in patients with ulcerative colitis (UC), but the mechanism is not clear. Carbon monoxide (CO) is the molecule regulating the resting membrane potential (RMP) gradient across colonic smooth muscle wall. Changes in RMP will affect the contractility of smooth muscle. In this study, we investigated the altered colonic motility in dextran sodium sulfate-induced UC mice and the role of CO. The results showed that in the UC group, the frequency of spontaneous colonic contractions was increased while the AUC was decreased compared with the control group. HO-1-, but not HO-2-, positive cells were increased in the colonic smooth muscle wall of the UC group. These HO-1-positive cells were mainly in the myenteric plexus and PGP9.5 positive, suggesting neuronal overproduction of CO. The RMP of circular smooth muscle cells (SMCs) in the colon of UC group was hyperpolarized compared with that of control group. In control group, application of CORM-3, a CO donor, altered colonic spontaneous contractions by increasing their frequency and decreasing amplitude. In the UC group, ZnPPIX, a HO-1 inhibitor, reduced the frequency and increased the amplitude. CORM-3 hyperpolarized the RMP of colonic SMCs and abolished its gradient in the control group, while ZnPPIX depolarized the RMP of colonic SMCs and restored its gradient in the UC group. CO produced by HO-1 upregulation is the main factor behind the altered colonic motility seen in UC mice. CO is a potential candidate as a therapeutic target for patients with UC who suffer from abnormal colonic motility.NEW & NOTEWORTHY Carbon monoxide (CO) produced by HO-1 upregulation in myenteric plexus is the main factor that abolishes the RMP gradient across colonic muscle wall causing the altered colonic motility seen in experimental ulcerative colitis (UC) mice. CO is a potential candidate as a therapeutic target for patients with UC who suffer from abnormal colonic motility.

Mechanism of Action and Therapeutic Implications of Nrf2/HO-1 in Inflammatory Bowel Disease

Oxidative stress (OS) is a key factor in the generation of various pathophysiological conditions. Nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) is a major transcriptional regulator of antioxidant reactions. Heme oxygenase-1 (HO-1), a gene regulated by Nrf2, is one of the most critical cytoprotective molecules. In recent years, Nrf2/HO-1 has received widespread attention as a major regulatory pathway for intracellular defense against oxidative stress. It is considered as a potential target for the treatment of inflammatory bowel disease (IBD). This review highlights the mechanism of action and therapeutic significance of Nrf2/HO-1 in IBD and IBD complications (intestinal fibrosis and colorectal cancer (CRC)), as well as the potential of phytochemicals targeting Nrf2/HO-1 in the treatment of IBD. The results suggest that the therapeutic effects of Nrf2/HO-1 on IBD mainly involve the following aspects: (1) Controlling of oxidative stress to reduce intestinal inflammation and injury; (2) Regulation of intestinal flora to repair the intestinal mucosal barrier; and (3) Prevention of ferroptosis in intestinal epithelial cells. However, due to the complex role of Nrf2/HO-1, a more nuanced understanding of the exact mechanisms involved in Nrf2/HO-1 is the way forward for the treatment of IBD in the future.

Crucial role of carbon monoxide as a regulator of diarrhea caused by cholera toxin: Evidence of direct interaction with toxin

The present study evaluated the role of heme oxygenase 1 (HO-1)/carbon monoxide (CO) pathway in the cholera toxin-induced diarrhea and its possible action mechanism. The pharmacological modulation with CORM-2 (a CO donor) or Hemin (a HO-1 inducer) decreased the intestinal fluid secretion and Cl- efflux, altered by cholera toxin. In contrast, ZnPP (a HO-1 inhibitor) reversed the antisecretory effect of Hemin and potentiated cholera toxin-induced intestinal secretion. Moreover, CORM-2 also prevented the alteration of intestinal epithelial architecture and local vascular permeability promoted by cholera toxin. The intestinal absorption was not altered by any of the pharmacological modulators. Cholera toxin inoculation also increased HO-1 immunoreactivity and bilirubin levels, a possible protective physiological response. Finally, using fluorometric technique, ELISA assay and molecular docking simulations, we show evidence that CO directly interacts with cholera toxin, forming a complex that affects its binding to GM1 receptor, which help explain the antisecretory effect. Thus, CO is an essential molecule for protection against choleric diarrhea and suggests its use as a possible therapeutic tool.

Hemin Ameliorates the Inflammatory Activity in the Inflammatory Bowel Disease: A Non-Clinical Study in Rodents

BACKGROUND

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract. Currently, there is no cure, and pharmacological treatment aims to induce and maintain remission in patients, so it is essential to investigate new possible treatments. Hemin is a heme-oxygenase inducer which can confer anti-inflammatory, cytoprotective, and antiapoptotic effects; therefore, it can be considered an asset for different gastrointestinal pathologies, namely for IBD.

AIM

This experiment aims to evaluate the efficacy and safety of hemin, in a chronic 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis model in rodents.

METHODS

The induction of chronic colitis consisted of five weekly intrarectal administrations of 1% TNBS. Then, the mice were treated daily with 5 mg/kg/day or 10 mg/kg/day of hemin, through intraperitoneal injections, for 14 days.

RESULTS

Hemin demonstrated an anti-inflammatory effect through the reduction in tumor necrosis factor (TNF)-α levels, fecal calprotectin, and fecal hemoglobin. It was also found to be safe in terms of extraintestinal manifestations, since hemin did not promote renal and/or hepatic changes.

CONCLUSIONS

Hemin could become an interesting tool for new possible pharmacological approaches in the management of IBD.

Modulatory Role of Carbon Monoxide on the Inflammatory Response and Oxidative Stress Linked to Gastrointestinal Disorders

Significance: Carbon monoxide (CO) is an endogenous gaseous mediator that plays an important role in maintaining gastrointestinal (GI) tract homeostasis, acting in mucosal defense, and providing negative modulation of pathophysiological markers of clinical conditions. Recent Advances: Preclinical studies using animal models and/or cell culture show that CO can modulate the inflammatory response and oxidative stress in GI mucosal injuries and pathological conditions, reducing proinflammatory cytokines and reactive oxygen species, while increasing antioxidant defense mechanisms. Critical Issues: CO has potent anti-inflammatory and antioxidant effects. The defense mechanisms of the GI tract are subject to aggression by different chemical agents (e.g., drugs and ethanol) as well as complex and multifactorial diseases, with inflammation and oxidative stress as strong triggers for the deleterious effects. Thus, it is possible that CO acts on a variety of molecules involved in the inflammatory and oxidative signaling cascades, as well as reinforcing several defense mechanisms that maintain GI homeostasis. Future Directions: CO-based therapies are promising tools for the treatment of GI disorders, such as gastric and intestinal injuries, inflammatory bowel disease, and pancreatitis. Therefore, it is necessary to develop safe and selective CO-releasing agents and/or donor drugs to facilitate effective treatments and methods for analysis of CO levels that are simple and inexpensive. Antioxid. Redox Signal. 37, 98-114.

Rectal administration of carbon monoxide inhibits the development of intestinal inflammation and promotes intestinal wound healing via the activation of the Rho-kinase pathway in rats

The inhalation of carbon monoxide (CO) gas and the administration of CO-releasing molecules were shown to inhibit the development of intestinal inflammation in a murine colitis model. However, it remains unclear whether CO promotes intestinal wound healing. Herein, we aimed to evaluate the therapeutic effects of the topical application of CO-saturated saline enemas on intestinal inflammation and elucidate the underlying mechanism. Acute colitis was induced with trinitrobenzene sulfonic acid (TNBS) in male Wistar rats. A CO-saturated solution was prepared via bubbling 50% CO gas into saline and was rectally administrated twice a day after colitis induction; rats were sacrificed 3 or 7 days after induction for the study of the acute or healing phases, respectively. The distal colon was isolated, and ulcerated lesions were measured. In vitro wound healing assays were also employed to determine the mechanism underlying rat intestinal epithelial cell restitution after CO treatment. CO solution rectal administration ameliorated acute TNBS-induced colonic ulceration and accelerated ulcer healing without elevating serum CO levels. The increase in thiobarbituric acid-reactive substances and myeloperoxidase activity after induction of acute TNBS colitis was also significantly inhibited after CO treatment. Moreover, the wound healing assays revealed that the CO-saturated medium enhanced rat intestinal epithelial cell migration via the activation of Rho-kinase. In addition, the activation of Rho-kinase in response to CO treatment was confirmed in the inflamed colonic tissue. Therefore, the rectal administration of a CO-saturated solution protects the intestinal mucosa from inflammation and accelerates colonic ulcer healing through enhanced epithelial cell restitution. CO may thus represent a novel therapeutic agent for the treatment of inflammatory bowel disease.

The Good and the Bad Side of Heme-Oxygenase-1 in the Gut

Significance: Mucosal immunity in the gut has the important task of protecting an organism against potential danger, but at the same time of staying silent in response to harmless antigens present in the intestinal lumen. The delicate balance between immune activation and tolerance is referred to as gut homeostasis. Recent Advances: It has become clear that different types of immune cells and several factors participate in the maintenance of gut homeostasis, having as a final goal the prevention of non-necessary inflammation. Immune cells of the myeloid lineage, such as macrophages located in the lamina propria, represent the most abundant leukocyte population in the intestine and play a critical role in keeping the immune system silent, via the production of the anti-inflammatory cytokine interleukin-10. Critical Issues: Gut macrophages are an important source of the oxidative enzyme heme-oxygenase-1 (HO-1), which has crucial immune-modulatory properties. The protective role of HO-1 in the control of the intestinal inflammation, and its connection with the enteric flora have been demonstrated in experimental settings as well as in human biological samples. Future Directions: Loss of the gut homeostasis gives rise to conditions of acute inflammation that may degenerate into chronic disease, eventually leading to carcinogenesis. Understanding the mechanisms that regulate this enzyme will disclose novel therapeutic approaches that are designed to control chronic inflammation in the intestine.

Non-invasive Assessment of Fecal Stress Biomarkers in Hunting Dogs During Exercise and at Rest

Intense exercise causes to organisms to have oxidative stress and inflammation at the gastrointestinal (GI) level. The reduction in intestinal blood flow and the exercise-linked thermal damage to the intestinal mucosa can cause intestinal barrier disruption, followed by an inflammatory response. Furthermore, the adaptation to exercise may affect the gut microbiota and the metabolome of the biofluids. The aim of the present research was to evaluate the presence of a GI derangement in hunting dogs through a non-invasive sampling as a consequence of a period of intense exercise in comparison with samples collected at rest. The study included nine dogs that underwent the same training regime for hunting wild boar. In order to counterbalance physiological variations, multiple-day replicates were collected and pooled at each experimental point for each dog. The samples were collected immediately at rest before the training (T0), after 60 days of training (T1), after 60 days of hunting wild boar (T2), and finally, at 60 days of rest after hunting (T3). A number of potential stress markers were evaluated: fecal cortisol metabolites (FCMs) as a major indicator of altered physiological states, immunoglobulin A (IgA) as an indicator of intestinal immune protection, and total antioxidant activity [total antioxidant capacity (TAC)]. Since stool samples contain exfoliated cells, we investigated also the presence of some transcripts involved in GI permeability [occludin (OCLN), protease-activated receptor-2 (PAR-2)] and in the inflammatory mechanism [interleukin (IL)-8, IL-6, IL-1b, tumor necrosis factor alpha (TNFα), calprotectin (CALP), heme oxygenase-1 (HO-1)]. Finally, the metabolome and the microbiota profiles were analyzed. No variation in FCM and IgA content and no differences in OCLN and CALP gene expression between rest and training were observed. On the contrary, an increase in PAR-2 and HO-1 transcripts, a reduction in total antioxidant activity, and a different profile of microbiota and metabolomics data were observed. Collectively, the data in the present study indicated that physical exercise in our model could be considered a mild stressor stimulus.

Potential Anti-Inflammatory Effect of Escitalopram in Iodoacetamide-Induced Colitis in Depressed Ovariectomized Rats: Role of α7-nAChR

Escitalopram, a drug of choice in the treatment of depression, was recently shown to possess an anti-inflammatory activity. The aim of the present study was to elucidate the effect of escitalopram on peripheral inflammatory cascades in iodoacetamide-induced colitis associated with depressive behavior in ovariectomized rats. Moreover, the role of α-7 nicotinic acetylcholine receptor in mediating the anti-colitic effect of escitalopram was examined using a nicotinic receptor antagonist methyllycaconitine citrate. Colitis was induced by intracolonic injection of 4% iodoacetamide in ovariectomized rats. Escitalopram (10 mg/kg/day, i.p.) was then injected for 1 week and several parameters including macroscopic (colon mass index and ulcerative area), microscopic (histopathology and scoring), and biochemical (myeloperoxidase and tumor necrosis factor-α) were determined. Colitis induction in ovariectomized rats resulted in a marked increase in colon mass index, ulcerative area, histopathological scoring, myeloperoxidase activity and tumor necrosis factor-α levels. These effects were ameliorated by escitalopram, even in the presence of methyllycaconitine indicating that α-7 nicotinic acetylcholine receptor does not mediate the anti-inflammatory effect of escitalopram. The present study revealed the beneficial effect of escitalopram in iodoacetamide induced colitis in ovariectomized rats and suggests that it may represent a new therapeutic agent for the treatment of inflammatory bowel disease, especially in patients with or at high risk of depressive behavior.

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.

Cilostazol against 2,4,6‐trinitrobenzene sulfonic acid‐induced colitis: Effect on tight junction, inflammation, and apoptosis

Background

Aim

Methods

Results

Conclusion

Heme oxygenase-1 prevents murine intestinal inflammation

Heme oxygenases (HOs) are rate-limiting enzymes catabolizing heme to biliverdin, ferrous iron, and carbon monoxide, and of the three HO isoforms identified, HO-1 plays a protective role against inflammatory processes. In this study, we investigated the possible role of HO-1 in intestinal inflammation. Acute colitis was induced in male C57BL/6 (wild-type) and homozygous BTB and CNC homolog 1 (Bach1)-deficient mice, which show high HO-1 expression in the colonic mucosa, using dextran sodium sulfate. The disease activity index, myeloperoxidase activity, and inflammatory cytokines in the colonic mucosa were evaluated 7 days after dextran sodium sulfate-dependent colitis induction. We also evaluated the impact of HO-1 inhibition using zinc protoporphyrin IX (25 mg/kg i.p., daily). After dextran sodium sulfate administration, HO-1 mRNA and protein expression increased in a time-dependent manner. Disease activity index score, myeloperoxidase activity, and colonic production of TNF-α and IFN-γ were increased after dextran sodium sulfate administration, and co-administration of zinc protoporphyrin IX enhanced their increase. In addition, disease activity index in Bach1-deficient was significantly lower after dextran sodium sulfate administration than that in wild type mice. These results indicate that HO-1 plays a protective role against dextran sodium sulfate-induced intestinal inflammation, possibly by regulating pro-inflammatory cytokines in intestinal tissues.

Hemin reduces inflammation associated with TNBS-induced colitis

Purpose

Hemin is a heme-oxygenase inducer, which can confer anti-inflammatory, cytoprotective, and antiapoptotic effects. These properties are beneficial therapeutical effects to inflammatory bowel disease (IBD). IBD is a worldwide health problem characterized by chronic inflammation of intestinal epithelium, which promotes intestinal and extraintestinal symptomatology. Current treatment only induces and maintains the patient in remission and results in many side effects. The research of other pharmacologic approaches is crucial to the treatment of IBD. The aim of this study is to evaluate the effect of hemin in the 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis model.

Materials and methods

Male CD-1 mice with TNBS-induced colitis were treated with a daily dose of hemin 5 mg/kg body weight/day and 10 mg/kg body weight/day intraperitoneal, during 4 days. The evaluated parameters were fecal hemoglobin, alkaline phosphatase (ALP), myeloperoxidase, tumor necrosis factor-α, interleukin (IL)-1β, IL-10, histopathologic analysis, urea, creatinine, and alanine aminotransferase.

Results

The hemin-treated mice presented a decrease in fecal hemoglobin, ALP, and proinflammatory cytokine concentrations compared to the TNBS group. Histopathology analysis confirmed the decrease in lesion extension produced by hemin.

Conclusion

These findings suggest that hemin treatment reduces hemorrhagic focus, intestinal damage, tissue inflammation, and lesion extension associated with experimental colitis.

Heme Oxygenase-1 as a Modulator of Intestinal Inflammation Development and Progression

Heme Oxygenase 1 (HMOX1) is an enzyme that catalyzes the reaction that degrades the heme group contained in several important proteins, such as hemoglobin, myoglobin, and cytochrome p450. The enzymatic reaction catalyzed by HMOX1 generates Fe2+, biliverdin and CO. It has been shown that HMOX1 activity and the by-product CO can downmodulate the damaging immune response in several models of intestinal inflammation as a result of pharmacological induction of HMOX1 expression and the administration of non-toxic amounts of CO. Inflammatory Bowel Diseases, which includes Crohn's Disease (CD) and Ulcerative Colitis (UC), are one of the most studied ailments associated to HMOX1 effects. However, microbiota imbalances and infections are also important factors influencing the occurrence of acute and chronic intestinal inflammation, where HMOX1 activity may play a major role. As part of this article we discuss the immune modulatory capacity of HMOX1 during IBD, as well during the infections and interactions with the microbiota that contribute to this inflammatory disease.

Mkp-1 cross-talks with Nrf2/Ho-1 pathway protecting against intestinal inflammation

Inflammatory bowel disease (IBD) is associated with intense oxidative stress, contributes to colonic damage and tumorigenesis. Mitogen-activated protein kinase phosphatase 1 (Mkp-1) is an essential negative regulator of the innate immune response. However, its role in colitis, and its association with the nuclear factor-erythroid 2 related factor 2 (Nrf2), a master regulator of cytoprotection program against oxidative stress, in inflammatory response, is elusive. In this study, we found that increased expression of Mkp-1, Nrf2, and heme oxygenase 1 (Ho-1) was correlated in colonic tissues in patients with ulcerative colitis and Crohn's disease, as well as wild-type mice with colitis induced by dextran sodium sulfate (DSS). Mkp-1^-/- mice were more susceptible to DSS-induced colitis with more severe crypt injury and inflammation. Mechanistically, directly interacting with the DIDLID motif of Nrf2, Mkp-1 increased Nrf2 stability and positively regulated the constitutive and lipopolysaccharide (LPS)-inducible Nrf2/Ho-1 expression. Conversely, upon exposure to LPS, Nrf2 activated Mkp-1 transcription through the antioxidant response elements in the promoter of Mkp-1. Our results revealed a novel link between Mkp-1 and Nrf2 signaling pathways in protecting against colonic inflammation. Mkp-1 might be a therapeutic target for IBD.

Heme oxygenase-1 prevents murine intestinal inflammation

Heme oxygenases (HOs) are rate-limiting enzymes catabolizing heme to biliverdin, ferrous iron, and carbon monoxide, and of the three HO isoforms identified, HO-1 plays a protective role against inflammatory processes. In this study, we investigated the possible role of HO-1 in intestinal inflammation. Acute colitis was induced in male C57BL/6 (wild-type) and homozygous BTB and CNC homolog 1 (Bach1)-deficient mice, which show high HO-1 expression in the colonic mucosa, using dextran sodium sulfate. The disease activity index, myeloperoxidase activity, and inflammatory cytokines in the colonic mucosa were evaluated 7 days after dextran sodium sulfate-dependent colitis induction. We also evaluated the impact of HO-1 inhibition using zinc protoporphyrin IX (25 mg/kg i.p., daily). After dextran sodium sulfate administration, HO-1 mRNA and protein expression increased in a time-dependent manner. Disease activity index score, myeloperoxidase activity, and colonic production of TNF-α and IFN-γ were increased after dextran sodium sulfate administration, and co-administration of zinc protoporphyrin IX enhanced their increase. In addition, disease activity index in Bach1-deficient was significantly lower after dextran sodium sulfate administration than that in wild type mice. These results indicate that HO-1 plays a protective role against dextran sodium sulfate-induced intestinal inflammation, possibly by regulating pro-inflammatory cytokines in intestinal tissues.

Galantamine anti-colitic effect: Role of alpha-7 nicotinic acetylcholine receptor in modulating Jak/STAT3, NF-κB/HMGB1/RAGE and p-AKT/Bcl-2 pathways

Vagal stimulation controls systemic inflammation and modulates the immune response in different inflammatory conditions, including inflammatory bowel diseases (IBD). The released acetylcholine binds to alpha-7 nicotinic acetylcholine receptor (α7 nAChR) to suppress pro-inflammatory cytokines. This provides a new range of potential therapeutic approaches for controlling inflammatory responses. The present study aimed to assess whether galantamine (Galan) anti-inflammatory action involves α7 nAChR in a 2,4,6-trinitrobenzene sulfonic acid (TNBS) model of colitis and to estimate its possible molecular pathways. Rats were assigned into normal, TNBS, sulfasalazine (Sulfz), Galan treated (10 mg/kg), methyllycaconitine (MLA; 5.6 mg/kg), and MLA + Galan groups. Drugs were administered orally once per day (11 days) and colitis was induced on the 8^th day. Galan reduced the TNBS-induced ulceration, colon mass index, colonic MDA, neutrophils adhesion and infiltration (ICAM-1/MPO), inflammatory mediators (NF-κB, TNF-α, HMGB1, and RAGE), while increased the anti-apoptotic pathway (p-Akt/Bcl-2). Mechanistic study revealed that Galan increased the anti-inflammatory cytokine IL-10, phosphorylated Jak2, while reduced the inflammation controller SOCS3. However, combining MLA with Galan abrogated the beneficial anti-inflammatory/anti-apoptotic signals. The results of the present study indicate that Galan anti-inflammatory/-apoptotic/ -oxidant effects originate from the stimulation of the peripheral α7 nAChR, with the involvement of the Jak2/SOCS3 signaling pathway.

Enzymatically synthesized glycogen inhibits colitis through decreasing oxidative stress

Inflammatory bowel diseases are a group of chronic inflammation conditions of the gastrointestinal tract. Disruption of the mucosal immune response causes accumulation of oxidative stress, resulting in the induction of inflammatory bowel disease. In this study, we investigated the effect of enzymatically synthesized glycogen (ESG), which is produced from starch, on dextran sulfate sodium (DSS)- and 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in C57BL/6 mice. Oral administration of ESG suppressed DSS- and TNBS-induced shortening of large intestine in female mice and significant decreased DSS-induced oxidative stress and TNBS-induced pro-inflammatory cytokine expression in the large intestine. ESG increase in the expression levels of heme oxygenase-1 (HO-1) and NF-E2-related factor-2 (Nrf2), a transcription factor for HO-1 expressed in the large intestine. Furthermore, ESG-induced HO-1 and Nrf2 were expressed mainly in intestinal macrophages. ESG is considered to be metabolized to resistant glycogen (RG) during digestion with α-amylase in vivo. In mouse macrophage RAW264.7 cells, RG, but not ESG decreased 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced reactive oxygen species (ROS). Knockdown of Nrf2 inhibited RG-induced HO-1 expression and negated the decrease in AAPH-induced ROS brought about by RG. RG up-regulated the protein stability of Nrf2 to decrease the formation of Nrf2-Keap1 complexes. RG-induced phosphorylation of Nrf2 at Ser40 was suppressed by ERK1/2 and JNK inhibitors. Our data indicate that ESG, digested with α-amylase to RG, suppresses DSS- and TNBS-induced colitis by increasing the expression of HO-1 in the large intestine of mice. Furthermore, we demonstrate that RG induces HO-1 expression by promoting phosphorylation of Nrf2 at Ser40 through activation of the ERK1/2 and JNK cascade in macrophages.

Improvement of side-effects and treatment on the experimental colitis in mice of a resin microcapsule-loading hydrocortisone sodium succinate

CONTEXT

Extensive or long-time use of corticosteroids often causes many toxic side-effects. The ion exchange resins and the coating material, Eudragit, can be used in combination to form a new oral delivery system to deliver corticosteroids.

OBJECTIVES

The resin microcapsule (DRM) composed by Amberlite 717 and Eudragit S100 was used to target hydrocortisone (HC) to the colon in order to improve its treatment effect on ulcerative colitis (UC) and reduce its toxic side-effects.

METHODS

Hydrocortisone sodium succinate (HSS) was sequentially encapsulated in Amberlite 717 and Eudragit S100 to prepare the HSS-loaded resin microcapsule (HSS-DRM). The scanning electron microscopy (SEM) was employed to investigate the morphology and structure of HSS-DRM. The in vitro release and in vivo studies of pharmacokinetics and intestinal drug residues in rat were used to study the colon-targeting of HSS-DRM. The mouse induced by 2,4,6-trinitrobenzenesulfonic acid was used to study the treatment of HSS-DRM on experimental colitis.

RESULTS

SEM study showed good morphology and structure of HSS-DRM. In the in vitro release study, > 80% of HSS was released in the colon environment (pH 7.4). The in vivo studies showed good colon-targeting of HSS-DRM (T_max= 0.97 h, C_max= 118.28 µg/mL of HSS; T_max = 2.16 h, C_max = 64.47 µg/mL of HSS-DRM). Moreover, the HSS-DRM could reduce adverse reactions induced by HSS and had good therapeutic effects on the experimental colitis.

CONCLUSIONS

The resin microcapsule system has good colon-targeting and can be used in the development of colon-targeting preparations.

Bacteria-Derived Compatible Solutes Ectoine and 5α-Hydroxyectoine Act as Intestinal Barrier Stabilizers to Ameliorate Experimental Inflammatory Bowel Disease

Earlier studies showed that the compatible solute ectoine (1) given prophylactically before induction of colitis by 2,4,6-trinitrobenzenesulfonic acid (TNBS) in rats prevented histological changes induced in the colon and the associated rise in inflammatory mediators. This study was therefore conducted to investigate whether ectoine (1) and its 5α-hydroxy derivative (2) would also be effective in treating an already established condition. Two days after inducing colitis in rats by instilling TNBS/alcohol in the colon, animals were treated orally once daily for 1 week with either 1 or 2 (50, 100, 300 mg/kg). Twenty-four hours after the last drug administration rats were sacrificed. Ulcerative lesions and colon mass indices were reduced by 1 and 2 in a bell-shaped manner. Best results were obtained with 100 mg/kg ectoine (1) and 50 mg/kg 5α-hydroxyectoine (2). The solutes normalized the rise in myeloperoxidase, TNFα, and IL-1β induced by TNBS but did not affect levels of reduced glutathione or ICAM-1, while reducing the level of fecal calprotectin, an established marker for inflammatory bowel disease. The findings indicate that the naturally occurring compatible solutes ectoine (1) and 5α-hydroxyectoine (2) possess an optimum concentration that affords maximal intestinal barrier stabilization and could therefore prove useful for better management of human inflammatory bowel disease.

Investigation of the colon-targeting, improvement on the side-effects and therapy on the experimental colitis in mouse of a resin microcapsule loading dexamethasone sodium phosphate

CONTEXT

Dexamethasone is the major drug in the treatment of ulcerative colitis (UC). However, the extensive or long-time use of dexamethasone causes many toxic side-effects. Ion exchange resins react with external-ions through their own functional groups and Eudragit S occurs degradation when pH > 7. These features make them suitable for oral delivery system.

OBJECTIVE

Resin microcapsule (DRM) composed by 717 anion exchange resin and Eudragit S100 was used to target dexamethasone to the colon to improve its treatment effect on UC and reduce its toxic side-effects.

RESULTS

Dexamethasone sodium phosphate (DXSP) was sequentially encapsulated in 717 anion-exchange resin and Eudragit S100 to prepare the DXSP-loaded resin microcapsule (DXSP-DRM). The in vitro release study and in vivo study of pharmacokinetics and the intestinal drug residues in rat demonstrated the good colon-targeting of DXSP-DRM. Moreover, the DXSP-DRM can reduce the toxic side-effects induced by DXSP and have good therapeutic effects on colitis mouse induced by 2,4,6-trinitrobenzenesulfonic acid.

DISCUSSION

Dexamethasone can be targeted to the colon by DRM, thereby enhancing its treatment effect and reducing its toxic side effects.

CONCLUSION

The resin microcapsule system has good colon-targeting and can be used in the development of colon-targeted preparations.

Protective role of hemeoxygenase-1 in gastrointestinal diseases

Disorders and diseases of the gastrointestinal system encompass a wide array of pathogenic mechanisms as a result of genetic, infectious, neoplastic, and inflammatory conditions. Inflammatory diseases in general are rising in incidence and are emerging clinical problems in gastroenterology and hepatology. Hemeoxygenase-1 (HO-1) is a stress-inducible enzyme that has been shown to confer protection in various organ-system models. Its downstream effectors, carbon monoxide and biliverdin have also been shown to offer these beneficial effects. Many studies suggest that induction of HO-1 expression in gastrointestinal tissues and cells plays a critical role in cytoprotection and resolving inflammation as well as tissue injury. In this review, we examine the protective role of HO-1 and its downstream effectors in modulating inflammatory diseases of the upper (esophagus and stomach) and lower (small and large intestine) gastrointestinal tract, the liver, and the pancreas. Cytoprotective, anti-inflammatory, anti-proliferative, antioxidant, and anti-apoptotic activities of HO-1 make it a promising if not ideal therapeutic target for inflammatory diseases of the gastrointestinal system.

TI-I-174, a Synthetic Chalcone Derivative, Suppresses Nitric Oxide Production in Murine Macrophages via Heme Oxygenase-1 Induction and Inhibition of AP-1

Chalcones (1,3-diaryl-2-propen-1-ones), a flavonoid subfamily, are widely known for their anti-inflammatory properties. Propenone moiety in chalcones is known to play an important role in generating biological responses by chalcones. In the present study, we synthesized chalcone derivatives structurally modified in propenone moiety and examined inhibitory effect on nitric oxide (NO) production and its potential mechanisms. Among the chalcone derivatives used for this study, TI-I-174 (3-(2-Hydroxyphenyl)-1-(thiophen-3-yl)prop-2-en-1-one) most potently inhibited lipopolysaccharide (LPS)-stimulated nitrite production in RAW 264.7 macrophages. TI-I-174 treatment also markedly inhibited inducible nitric oxide synthase (iNOS) expression. However, TI-I-174 did not significantly affect production of IL-6, cyclooxygenase-2 (COX-2) and tumor necrosis factor-α (TNF-α), implying that TI-I-174 inhibits production of inflammatory mediators in a selective manner. Treatment of macrophages with TI-I-174 significantly inhibited transcriptional activity of activator protein-1 (AP-1) as determined by luciferase reporter gene assay, whereas nuclear factor-κB (NF-κB) activity was not affected by TI-I-1744. In addition, TI-I-174 significantly inhibited activation of c-Jun-N-Terminal kinase (JNK) without affecting ERK1/2 and p38MAPK, indicating that down-regulation of iNOS gene expression by TI-I-174 is mainly attributed by blockade of JNK/AP-1 activation. We also demonstrated that TI-I-174 treatment led to an increase in heme oxygenase-1 (HO-1) expression both at mRNA and protein level. Transfection of siRNA targeting HO-1 reversed TI-I-174-mediated inhibition of nitrite production. Taken together, these results indicate that TI-I-174 suppresses NO production in LPS-stimulated RAW 264.7 macrophages via induction of HO-1 and blockade of AP-1 activation.

Heme oxygenase-1 has antitumoral effects in colorectal cancer: involvement of p53

The expression of heme oxygenase-1 (HO-1) has been shown to be up-regulated in colorectal cancer (CRC), but the role it plays in this cancer type has not yet been addressed. The aims of this study have been to analyze HO-1 expression in human invasive CRC, evaluate its correlation with clinical and histo-pathological parameters and to investigate the mechanisms through which the enzyme influences tumor progression. We confirmed that HO-1 was over-expressed in human invasive CRC and found that the expression of the enzyme was associated with a longer overall survival time. In addition, we observed in a chemically-induced CRC animal model that total and nuclear HO-1 expression increases with tumor progression. Our investigation of the mechanisms involved in HO-1 action in CRC demonstrates that the protein reduces cell viability through induction of cell cycle arrest and apoptosis and, importantly, that a functional p53 tumor suppressor protein is required for these effects. This reduction in cell viability is accompanied by modulation of the levels of p21, p27, and cyclin D1 and by modulation of Akt and PKC pathways. Altogether, our results demonstrate an antitumoral role of HO-1 and points to the importance of p53 status in this antitumor activity.

Heme oxygenase-1 ameliorates dextran sulfate sodium-induced acute murine colitis by regulating Th17/Treg cell balance

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is a group of autoimmune diseases characterized by nonspecific inflammation in the gastrointestinal tract. Recent investigations suggest that activation of Th17 cells and/or deficiency of regulatory T cells (Treg) is involved in the pathogenesis of IBD. Heme oxygenase (HO)-1 is a protein with a wide range of anti-inflammatory and immune regulatory function, which exerts significantly protective roles in various T cell-mediated diseases. In this study, we aim to explore the immunological regulation of HO-1 in the dextran sulfate sodium-induced model of experimental murine colitis. BALB/c mice were administered 4% dextran sulfate sodium orally; some mice were intraperitoneally pretreated with HO-1 inducer hemin or HO-1 inhibitor stannum protoporphyrin IX. The results show that hemin enhances the colonic expression of HO-1 and significantly ameliorates the symptoms of colitis with improved histological changes, accompanied by a decreased proportion of Th17 cells and increased number of Tregs in mesenteric lymph node and spleen. Moreover, induction of HO-1 down-regulates retinoic acid-related orphan receptor γt expression and IL-17A levels, while promoting Treg-related forkhead box p3 (Foxp3) expression and IL-10 levels in colon. Further study in vitro revealed that up-regulated HO-1 switched the naive T cells to Tregs when cultured under a Th17-inducing environment, which involved in IL-6R blockade. Therefore, HO-1 may exhibit anti-inflammatory activity in the murine model of acute experimental colitis via regulating the balance between Th17 and Treg cells, thus providing a possible novel therapeutic target in IBD.

CO and CO-releasing molecules (CO-RMs) in acute gastrointestinal inflammation

Carbon monoxide (CO) is enzymatically generated in mammalian cells alongside the liberation of iron and the production of biliverdin and bilirubin. This occurs during the degradation of haem by haem oxygenase (HO) enzymes, a class of ubiquitous proteins consisting of constitutive and inducible isoforms. The constitutive HO2 is present in the gastrointestinal tract in neurons and interstitial cells of Cajal and CO released from these cells might contribute to intestinal inhibitory neurotransmission and/or to the control of intestinal smooth muscle cell membrane potential. On the other hand, increased expression of the inducible HO1 is now recognized as a beneficial response to oxidative stress and inflammation. Among the products of haem metabolism, CO appears to contribute primarily to the antioxidant and anti-inflammatory effects of the HO1 pathway explaining the studies conducted to exploit CO as a possible therapeutic agent. This article reviews the effects and, as far as known today, the mechanism(s) of action of CO administered either as CO gas or via CO-releasing molecules in acute gastrointestinal inflammation. We provide here a comprehensive overview on the effect of CO in experimental in vivo models of post-operative ileus, intestinal injury during sepsis and necrotizing enterocolitis. In addition, we will analyse the in vitro data obtained so far on the effect of CO on intestinal epithelial cell lines exposed to cytokines, considering the important role of the intestinal mucosa in the pathology of gastrointestinal inflammation.

Oxidative stress: an essential factor in the pathogenesis of gastrointestinal mucosal diseases

Reactive oxygen species (ROS) are generated as by-products of normal cellular metabolic activities. Superoxide dismutase, glutathione peroxidase, and catalase are the enzymes involved in protecting cells from the damaging effects of ROS. ROS are produced in response to ultraviolet radiation, cigarette smoking, alcohol, nonsteroidal anti-inflammatory drugs, ischemia-reperfusion injury, chronic infections, and inflammatory disorders. Disruption of normal cellular homeostasis by redox signaling may result in cardiovascular, neurodegenerative diseases and cancer. ROS are produced within the gastrointestinal (GI) tract, but their roles in pathophysiology and disease pathogenesis have not been well studied. Despite the protective barrier provided by the mucosa, ingested materials and microbial pathogens can induce oxidative injury and GI inflammatory responses involving the epithelium and immune/inflammatory cells. The pathogenesis of various GI diseases including peptic ulcers, gastrointestinal cancers, and inflammatory bowel disease is in part due to oxidative stress. Unraveling the signaling events initiated at the cellular level by oxidative free radicals as well as the physiological responses to such stress is important to better understand disease pathogenesis and to develop new therapies to manage a variety of conditions for which current therapies are not always sufficient.

The relationship between serum bilirubin and Crohn's disease

BACKGROUND

The oxidative stress is thought to play an important role in Crohn's disease (CD). As serum bilirubin represents the major endogenous antioxidant, this article aimed to evaluate in a clinical study, whether serum bilirubin levels and genes affecting its systemic concentrations are associated with CD.

METHODS

This exploratory case-control study was based on pediatric (n = 119) and adult (n = 504) patients with CD and 370 appropriate healthy control subjects. The (GT)n and (TA)n dinucleotide variations in heme oxygenase 1 (HMOX1) and bilirubin UDP-glucuronosyl transferase (UGT1A1) gene promoters were determined by fragment analysis. Serum bilirubin levels were compared in a subset of 90 cases and 229 controls, for whom biochemical data were available.

RESULTS

Substantially lower serum bilirubin levels were detected in patients with CD compared with controls (7.4 versus 12.1 μmol/L, P < 10). Serum bilirubin levels were significantly lower in patients with CD within all UGT1A1*28 genotypes (P < 0.05). UGT1A1*28 homozygotes with wild-type NOD2 gene variant exhibited significant delay in CD manifestation (P = 0.004), while the protective effect of UGT1A1*28 homozygosity was lost in those patients with mutated NOD2 gene. No associations between CD risk and individual HMOX1 gene variants were observed.

CONCLUSIONS

CD is associated with significantly low serum bilirubin levels, most likely as a result of increased oxidative stress accompanying this inflammatory disease. UGT1A1*28 allele homozygosity, responsible for higher bilirubin levels, seems to be an important modifier of CD manifestation.

Preventive effect of agaro-oligosaccharides on non-steroidal anti-inflammatory drug-induced small intestinal injury in mice

BACKGROUND AND AIM

Non-steroidal anti-inflammatory drugs (NSAIDs), which are commonly used in clinical medicine, cause erosion, ulcers, and bleeding in the gastrointestinal tract. No effective agent for the prevention and treatment of small intestinal injury by NSAIDs has been established. This study investigates the effects of agaro-oligosaccharides (AGOs) on NSAID-induced small intestinal injury in mice.

METHODS

Mice were treated with indomethacin, an NSAID, to induce intestinal injury. The respective degrees of mucosal injury of mice that received AGO and control mice were compared. Heme oxygenase-1 (HO-1) expression using quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, and immunohistochemistry were measured. The expression of keratinocyte chemoattractant (KC) was measured using qRT-PCR and enzyme-linked immunosorbent assay.

RESULTS

AGO administration induced HO-1 expression in mouse small intestinal mucosa. Induction was observed mainly in F4/80 positive macrophages. The increased ulcers score, myeloperoxidase activity, and KC expression by indomethacin were inhibited by AGO administration. Conversely, HO inhibitor cancelled AGO-mediated prevention of intestinal injury. In mouse peritoneal macrophages, AGOs enhanced HO-1 expression and suppressed lipopolysaccharide-induced KC expression. Furthermore, AGOs enhanced the expressions of alternatively activated macrophage markers arginase-1, mannose receptor-1, and chitinase 3-like 3.

CONCLUSIONS

Results suggest that oral administration of AGOs prevents NSAID-induced intestinal injury.

Review article: carbon monoxide in gastrointestinal physiology and its potential in therapeutics

BACKGROUND

While carbon monoxide (CO) is a known toxin, it is now recognised that CO is also an important signalling molecule involved in physiology and pathophysiology.

AIMS

To summarise our current understanding of the role of endogenous CO in the regulation of gastrointestinal physiology and pathophysiology, and to potential therapeutic applications of modulating CO.

METHODS

This review is based on a comprehensive search of the Ovid Medline comprehensive database and supplemented by our ongoing studies evaluating the role of CO in gastrointestinal physiology and pathophysiology.

RESULTS

Carbon monoxide derived from haem oxygenase (HO)-2 is predominantly involved in neuromodulation and in setting the smooth muscle membrane potential, while CO derived from HO-1 has anti-inflammatory and antioxidative properties, which protect gastrointestinal smooth muscle from damage caused by injury or inflammation. Exogenous CO is being explored as a therapeutic agent in a variety of gastrointestinal disorders, including diabetic gastroparesis, post-operative ileus, organ transplantation, inflammatory bowel disease and sepsis. However, identifying the appropriate mechanism for safely delivering CO in humans is a major challenge.

CONCLUSIONS

Carbon monoxide is an important regulator of gastrointestinal function and protects the gastrointestinal tract against noxious injury. CO is a promising therapeutic target in conditions associated with gastrointestinal injury and inflammation. Elucidating the mechanisms by which CO works and developing safe CO delivery mechanisms are necessary to refine therapeutic strategies.

Activation of human biliverdin-IXα reductase by urea: generation of kinetically distinct forms during the unfolding pathway

Activation of enzymes by low concentrations of denaturants has been reported for a limited number of enzymes including lipocalin-type prostaglandin D synthase (L-PGDS) and adenylate kinase. During unfolding studies on human biliverdin-IXα reductase it was discovered that the enzyme is activated at low concentrations of urea. Under standard assay conditions the native enzyme displays pronounced substrate inhibition with biliverdin as variable substrate; however in the presence of 3M urea, the substrate inhibition is abolished and the enzyme exhibits Michaelian kinetics. When the initial rate kinetics with NADPH as variable substrate are conducted in 3M urea, the Vmax is increased 11-fold to 1.8μmol/min/mg and the apparent Km for biliverdin increases from 1 to 3μM. We report the existence of two kinetically distinct folded intermediates between the native and unfolded forms. When the period of incubation with urea was varied prior to measuring enzyme activity, the apparent Vmax was shown to decay to half that seen at zero time with a half life of 5.8minutes, while the apparent Km for NADPH remains constant at approximately 5μM. With NADH as cofactor the half life of the activated (A) form was 2.9minutes, and this form decays in 3M urea to a less active (LA) form. The apparent Km for NADH increases from 0.33mM to 2mM for the A and LA forms. These kinetically distinct species are reminiscent of the activity-enhanced and inactive forms of L-PGDS observed in the presence of urea and guanidine hydrochloride.

Oligosaccharides from agar inhibit murine intestinal inflammation through the induction of heme oxygenase-1 expression

BACKGROUND

Agarose is hydrolyzed easily to yield oligosaccharides, designated as agaro-oligosaccharides (AGOs). Recently, it has been demonstrated that AGOs induce heme oxygenase-1 (HO-1) expression in macrophages and that they might lead to anti-inflammatory property. Nevertheless, the molecular mechanism of AGO-mediated HO-1 induction remains unknown, as does AGOs' ability to elicit anti-inflammatory activity in vivo. This study was undertaken to uncover the mechanism of AGO-mediated HO-1 induction and to investigate the therapeutic effect of AGOs on intestinal inflammation.

METHODS

Mice were treated with 2,4,6-trinitrobenzene sulfonic acid (TNBS) to induce colitis. The respective degrees of mucosal injury of mice that had received AGO and control mice were compared. We investigated HO-1 expression using Western blotting, quantitative real-time PCR (qRT-PCR), and immunohistochemistry. The expression of tumor necrosis factor-α (TNF-α) was measured using qRT-PCR and enzyme-linked immunosorbent assay.

RESULTS

AGO administration induced HO-1 expression in colonic mucosa. The induction was observed mainly in F4/80 positive macrophages. Increased colonic damage and myeloperoxidase activity after TNBS treatment were inhibited by AGO administration. TNBS treatment induced TNF-α expression, and AGO administration suppressed induction. However, HO inhibitor canceled AGO-mediated amelioration of colitis. In RAW264 cells, AGOs enhanced HO-1 expression time-dependently and concentration-dependently and suppressed lipopolysaccharide-induced TNF-α expression. Furthermore, agarotetraose-mediated HO-1 induction required NF-E2-related factor 2 function and phosphorylation of c-jun N-terminal kinase.

CONCLUSIONS

We infer that AGO administration inhibits TNBS-induced colitis in mice through HO-1 induction in macrophages. Consequently, oral administration of AGOs might be an important therapeutic strategy for inflammatory bowel disease.

Low and medium but not high doses of green tea polyphenols ameliorated dextran sodium sulfate-induced hepatotoxicity and nephrotoxicity

Our previous study indicated that a diet containing a high dose (1%) of green tea polyphenols (GTPs) disrupted liver and kidney function via a reduction in antioxidant enzyme and heat shock protein (HSP) levels in both colitis and non-treated ICR mice. In the present study, we assessed the effects of 0.01%, 0.1%, and 1% dietary GTPs on liver and kidney physiological functioning in dextran sulfate sodium (DSS)-exposed and normal mice. GTPs at 0.01% and 0.1% significantly suppressed DSS-increased serum aspartate 2-oxoglutarate aminotransferase (AST) and alanine aminotransferase (ALT) levels. In contrast, GTPs at 1% increased kidney weight, serum creatinine levels, and thiobarbituric acid-reactive substances (TBARs) in both the kidney and the liver in normal mice, as compared with DSS-exposed mice. GTPs at 0.01% and 0.1% remarkably upregulated the expression of heme oxygenase-1 (HO-1) and heat shock protein 70 (HSP70) mRNA in the liver and kidney of mice exposed to DSS, whereas GTPs at 1% abolished it. Our results indicate that low and medium doses of GTPs have beneficial effects on DSS-induced hepatotoxicity and nephrotoxicity via upregulation of self-protective enzymes, while these effects disappeared at a high dose.

Novel effects of ectoine, a bacteria-derived natural tetrahydropyrimidine, in experimental colitis

Evidence suggests an important role of intestinal barrier dysfunction in the etiology of inflammatory bowel disease (IBD). Therefore stabilizing mucosal barrier function constitutes a new therapeutic approach in its management. Ectoine is a compatible solute produced by aerobic chemoheterotrophic and halophilic/halotolerant bacteria, where it acts as osmoprotectant and effective biomembrane stabilizer, protecting the producing cells from extreme environmental stress. Since this natural compound was also shown to prevent inflammatory responses associated with IBD, its potential usefulness was studied in a model of colitis. Groups of rats were treated orally with different doses of ectoine (30-300 mg/kg) or sulfasalazine (reference drug) daily for 11 days. On day 8 colitis was induced by intracolonic instillation of 2,4,6-trinitrobenzenesulfonic acid, when overt signs of lesions develop within the next 3 days. On day 12, blood was withdrawn from the retro-orbital plexus of the rats and the animals were sacrificed. The colon was excised and examined macroscopically and microscopically. Relevant parameters of oxidative stress and inflammation were measured in serum and colon homogenates. Induction of colitis led to marked weight loss, significant histopathological changes of the colon, and variable changes in levels of myeloperoxidase, reduced glutathione, malondialdehyde, and all inflammatory markers tested. Treatment with ectoine ameliorated the inflammatory changes in TNBS-induced colitis. This effect was associated with reduction in the levels of TNF-α, IL-1β, ICAM-1, PGE2 and LTB4. The findings suggest that intestinal barrier stabilizers from natural sources could offer new therapeutic measures for the management of IBD.

Ameliorative effects of 3,4-oxo-isopropylidene-shikimic acid on experimental colitis and their mechanisms in rats

The aim of the present study was to investigate the therapeutic effect and mechanism of 3,4-oxo-isopropylidene-shikimic acid (ISA) on 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats. (50, 100, 200 mg/kg) was administered for 14 days, 1 day after the induction of colitis by TNBS. The colonic injury and inflammation were assessed by macroscopic damage scores and myeloperoxidase (MPO) activity. Malondialdehyde (MDA) and nitric oxide (NO) levels, and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in plasma were measured with biochemical methods. Prostaglandin E2 (PGE2) level in colon was determined by radioimmunoassay. Expressions of inducible nitric oxide synthase (iNOS), cyclo-oxygenase-2 (COX-2), inhibitor kappa B-alpha (IκBα) and nuclear factor kappa B (NF-κB) p65 proteins in the colonic tissue were detected with immunohistochemistry. Enhanced colonic mucosal injury, inflammatory response and oxidative stress were observed in the animals clystered with TNBS, which was manifested as the significant increase in colon mucosal damage index, MPO activity, levels of MDA, NO and PGE2, as well as the expressions of iNOS, COX-2 and NF-κB p65 proteins in the colonic mucosa, and the significant decrease in expressions of IκBα proteins in the colonic mucosa. However, these parameters were found to be significantly ameliorated in rats treated with ISA at given doses, especially at 100 mg/kg and 200 mg/kg. Administration of ISA may have significant therapeutic effects on experimental colitis in rats, probably due to its mechanism of antioxidation, its inhibition of arachidonic acid metabolism and its modulation of the IκBα/NF-κB p65 expression.

BTB and CNC homolog 1 (Bach1) deficiency ameliorates TNBS colitis in mice: role of M2 macrophages and heme oxygenase-1

BACKGROUND

BTB and CNC homolog 1 (Bach1) is a transcriptional repressor of heme oxygenase-1 (HO-1), which plays an important role in the protection of cells and tissues against acute and chronic inflammation. However, the role of Bach1 in the gastrointestinal mucosal defense system remains little understood. HO-1 supports the suppression of experimental colitis and localizes mainly in macrophages in colonic mucosa. This study was undertaken to elucidate the Bach1/HO-1 system's effects on the pathogenesis of experimental colitis.

METHODS

This study used C57BL/6 (wild-type) and homozygous Bach1-deficient C57BL/6 mice in which colonic damage was induced by the administration of an enema of 2,4,6-trinitrobenzene sulfonic acid (TNBS). Subsequently, they were evaluated macroscopically, histologically, and biochemically. Peritoneal macrophages from the respective mice were isolated and analyzed. Then, wild-type mice were injected with peritoneal macrophages from the respective mice. Acute colitis was induced similarly.

RESULTS

TNBS-induced colitis was inhibited in Bach1-deficient mice. TNBS administration increased the expression of HO-1 messenger RNA and protein in colonic mucosa in Bach1-deficient mice. The expression of HO-1 mainly localized in F4/80-immunopositive and CD11b-immunopositive macrophages. Isolated peritoneal macrophages from Bach1-deficient mice highly expressed HO-1 and also manifested M2 macrophage markers, such as Arginase-1, Fizz-1, Ym1, and MRC1. Furthermore, TNBS-induced colitis was inhibited by the transfer of Bach1-deficient macrophages into wild-type mice.

CONCLUSIONS

Deficiency of Bach1 ameliorated TNBS-induced colitis. Bach1-deficient macrophages played a key role in protection against colitis. Targeting of this mechanism is applicable to cell therapy for human inflammatory bowel disease.

Piceatannol, a hydroxystilbene natural product, stabilizes HIF-1α protein by inhibiting HIF prolyl hydroxylase

To investigate the mechanisms underlying the biological activity of piceatannol (PCT), a hydroxystilbene natural product that has anti-colitic properties, we examined whether PCT could modulate hypoxia-inducible factor (HIF)-1 activity in human colon carcinoma cells. PCT induced HIF-1α protein, leading to induction of its target gene products, vascular endothelial growth factor and heme oxygenase-1, which are involved in amelioration of colitis. PCT induction of HIF-1α resulted from HIF-1α protein stabilization, which occurred through inhibition of HIF-prolyl hydroxylase-2 (HPH-2). PCT inhibition of HPH-2 was reversed by addition of ascorbate, a cofactor of HPH-2, but not the cosubstrate, 2-ketoglutarate, to the reaction mixture of an in vitro von Hippel-Lindau (VHL) capture assay, and pretreatment with ascorbate abrogated PCT induction of cellular HIF-1α. Moreover, PCT prevented hydroxylation of cellular HIF-1α and attenuated coimmunoprecipitation of Flag-VHL protein and HA-HIF-1α over-expressed in human embryonic kidney 293 cells. Structural analysis using derivatives of PCT revealed that the catechol moiety in PCT was required for the stabilization of HIF-1α protein. Taken together, PCT activation of HIF-1 resulting from inhibition of HPH-2 may be a molecular mechanism for an anti-colitic effect of the natural product.

Nadroparin sodium activates Nrf2/HO-1 pathway in acetic acid-induced colitis in rats

Effects of nadroparin sodium, a low molecular weight heparin, in colitis was investigated by analyzing proteins implicated in nuclear factor E2-related factor-2/heme oxygenase-1 (Nrf2/HO-1) and nuclear factor kappa B (NF-κB) pathways. Twenty-eight rats were used. Colitis was induced by acetic acid (AA). Nadroparin sodium was given to prevention and treatment groups in addition to AA. Colitis was assessed histologically and levels of proteins were analyzed with Western blot. Nadroparin not only prevented and ameliorated the AA-induced colitis histopathologically but also decreased expression of colon NF-κB, activator protein-1, cyclooxygenase-2, tumor necrosis factor-alpha, and IL-6, which were significantly increased in group AA compared to control. The accumulation of Nrf2 in nuclear fraction and HO-1 found low in group AA was increased with nadroparin (p < 0.05). The mean malondialdehyde level increased with AA and was decreased significantly with nadroparin prevention and treatment (p < 0.001). Nadroparin sodium has both protective and therapeutic effects against colonic inflammation via exerting anti-oxidative and anti-inflammatory effects by modulating Nrf2/HO-1 and NF-κB pathways.

Protective effects of 3,4-oxo-isopropylidene-shikimic acid on experimental colitis induced by trinitrobenzenesulfonic acid in rats

BACKGROUND

3,4-Oxo-isopropylidene-shikimic acid (ISA) is a derivative of shikimic acid (SA). SA is extracted from Illicium verum Hook.fil., which has been used in traditional Chinese medicine and used for treating vomiting, stomach aches, insomnia, skin inflammation, and rheumatic pain.

AIMS

To investigate the effects and the protective mechanism of 3,4-oxo-isopropylidene-shikimic acid on experimental colitis model induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS) in rats.

METHODS

Colitis in rats was induced by colonic administration with TNBS. ISA (50, 100, and 200 mg/kg) was administered for 12 days to experimental colitis rats. The inflammatory degree was assessed by macroscopic damage score, colon weight/length ratios (mg/cm), and myeloperoxidase (MPO) activity. Malondialdehyde (MDA), glutathione (GSH), and nitric oxide (NO) levels, and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), inducible nitric oxide synthase (iNOS) activities were measured with biochemical methods.

RESULTS

ISA significantly ameliorated macroscopic damage, reduced colon weight/length ratios and the activity of MPO, depressed MDA and NO levels and iNOS activity, and enhanced GSH level, and GSH-Px and SOD activities in the colon tissues of experimental colitis in a dose-dependent manner. Moreover, the effect of ISA (200 mg/kg) was as effective as sulfasalazine (500 mg/kg).

CONCLUSIONS

The findings of this study demonstrate the protective effect of ISA on experimental colitis, probably due to an antioxidant action.

Heme oxygenase-1 is protective against nonsteroidal anti-inflammatory drug-induced gastric ulcers

OBJECTIVES

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for the treatment of pain, fever, and inflammation. Long-term use of these drugs is associated with significant gastric injury. Activated neutrophils and oxidative stress seem to play a significant role in NSAID-induced gastric mucosal damage. The objective of our study is to examine the protective effects of an antioxidant and anti-inflammatory enzyme, heme oxygenase-1 (HO-1), in NSAID-induced gastric injury.

METHODS

Mice were intraperitoneally injected with indomethacin (10 mg/kg) or sham. A specific inducer of HO-1, cobalt protoporphyrin (5 mg/kg), was given 24 hours before indomethacin to allow for the expression of HO-1. Controls received sham treatment. Twenty-four hours after indomethacin injection, gastric tissue damage was examined with histology. HO-1 expression was measured with immunoblot; cytokine levels were measured with enzyme-linked immunosorbent assay. Neutrophil infiltration was quantified with myeloperoxidase assay. Using electron paramagnetic resonance and desferrioxamine, we measured the labile iron pool in the mouse stomach as a marker of oxidative stress.

RESULTS

Indomethacin caused gastric inflammation and ulcers, neutrophil activation, and increased tissue expression of interleukin-6 and tumor necrosis factor-alpha in mice. Inducing HO-1 with cobalt protoporphyrin reduced gastric inflammation, number of stomach ulcers, tissue neutrophil activation, and proinflammatory cytokine expression caused by indomethacin.

CONCLUSIONS

These findings suggest that the induction of an anti-inflammatory and cytoprotective enzyme HO-1 may be a strategy to overcome the gastrointestinal adverse effects limiting the use of NSAIDs.

High-dose green tea polyphenols induce nephrotoxicity in dextran sulfate sodium-induced colitis mice by down-regulation of antioxidant enzymes and heat-shock protein expressions

Previously, we reported that oral feeding of 1% green tea polyphenols (GTPs) aggravated the dextran sulfate sodium (DSS)-induced colitis in mice. In the present study, we assessed the toxicity of 1% GTPs in several organs from normal and DSS-exposed mice. Sixty-two male ICR mice were initially divided into four groups. Non-treated group (group 1, n = 15) was given standard diet and water, GTPs (group 2, n = 15) received 1% GTPs in diet and water, DSS (group 3, n = 15) received diet and 5% DSS in water, and GTPs + DSS group (group 4, n = 17) received 1% GTPs in diet and 5% DSS in water. We found that group 4 significantly increased (P < 0.05) kidney weight, the levels of serum creatinine and thiobarbituric acid-reactive substances in both kidney and liver, as compared with those in group 3. The mRNA expression levels of antioxidant enzymes and heat-shock proteins (HSPs) in group 4 were lower than those of group 3. For instance, heme oxygenase-1 (HO-1), HSP27, and 90 mRNA in the kidney of group 4 were dramatically down-regulated as compared with those of group 3. Furthermore, 1% GTPs diet decreased the expression of HO-1, NAD(P)H:quinone oxidoreductase 1 (NQO1) and HSP90 in kidney and liver of non-treated mice. Taken together, our results indicate that high-dose GTPs diet disrupts kidney functions through the reduction of antioxidant enzymes and heat-shock protein expressions in not only colitis but also non-treated ICR mice.