Inhibition of inducible nitric oxide synthase in the human intestinal epithelial cell line, DLD-1, by the inducers of heme oxygenase 1, bismuth salts, heme, and nitric oxide donors

Exogenous monosodium glutamate exacerbates lipopolysaccharide-induced neurobehavioral deficits, oxidative damage, neuroinflammation, and cholinergic dysfunction in rat brain

Extensive experimental evidence points to neuroinflammation and oxidative stress as major pathogenic events that initiate and drive the neurodegenerative process. Monosodium glutamate (MSG) is a widely used food additive in processed foods known for its umami taste-enhancing properties. However, concerns about its potential adverse effects on the brain have been raised. Thus, the present study investigated the impact of MSG on lipopolysaccharide (LPS)-induced neurotoxicity in rat brains. Wistar rats weighing between 180 g and 200 g were randomly allocated into four groups: control (received distilled water), MSG (received 1.5 g/kg/day), LPS (received 250 µg/kg/day), and LPS + MSG (received LPS, 250 µg/kg, and MSG, 1.5 g/kg). LPS was administered intraperitoneally for 7 days while MSG was administered orally for 14 days. Our results showed that MSG exacerbated LPS-induced impairment in locomotor and exploratory activities in rats. Similarly, MSG exacerbated LPS-induced oxidative stress as evidenced by increased levels of malondialdehyde (MDA) with a concomitant decrease in levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione-s-transferase (GST) in the brain tissue. In addition, MSG potentiated LPS-induced neuroinflammation, as indicated by increased levels of pro-inflammatory cytokines such as interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) as well as myeloperoxidase (MPO) and nitric oxide (NO) in the brain. Moreover, MSG aggravated LPS-induced cholinergic dysfunction, as demonstrated by increased activity of acetylcholinesterase (AChE) in the brain. Further, we found a large number of degenerative neurons widespread in hippocampal CA1, CA3 regions, cerebellum, and cortex according to H&E staining. Taken together, our findings suggest that MSG aggravates LPS-induced neurobehavioral deficits, oxidative stress, neuroinflammation, cholinergic dysfunction, and neurodegeneration in rat brains.

Cooperative interactions between Veillonella ratti and Lactobacillus acidophilus ameliorate DSS-induced ulcerative colitis in mice

Veillonella and Lactobacillus species are key regulators of a healthy gut environment through metabolic cross-feeding, influencing lactic acid and short-chain fatty acid (SCFA) levels, which are crucial for gut health. This study aims to investigate how Veillonella ratti (V. ratti) and Lactobacillus acidophilus (LA) interact with each other and alleviate dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in a mouse model. We assess their metabolic interactions regarding carbon sources through co-culturing in a modified medium. In the in vitro experiments, V. ratti and LA were inoculated in mono-cultures and co-culture, and viable cell counts, OD600, pH, lactic acid, glucose and SCFAs were measured. For the in vivo experiment, 60 C57BL/6 mice were randomly divided into five groups and administered V. ratti and LA alone or in combination via oral gavage (1 × 109 CFU mL-1 per day per mouse) for 14 days. On the seventh day, 2.5% DSS was added to the drinking water to induce colitis. The effects of these probiotics on UC were evaluated by assessing intestinal barrier integrity and intestinal inflammation in the gut microenvironment. In vitro results demonstrated that co-culturing V. ratti with LA significantly increased viable cell numbers, lactic acid production, and SCFA production, while reducing pH and glucose levels in the medium. In vivo findings revealed that intervention with V. ratti, particularly in combination with LA, alleviated symptoms, including weight loss, colon shortening, and tissue damage. These probiotics mitigated intestinal inflammation by down-regulating pro-inflammatory molecules, such as IL-6, IL-1β, IL-γ, iNOS, and IFN-γ, as well as oxidative stress markers, including MDA and MPO. Concurrently, they upregulated the activity of anti-inflammatory enzymes, namely, SOD and GSH, and promoted the production of SCFAs. The combined intervention of V. ratti and LA significantly increased acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and total SCFAs in cecal contents. Furthermore, the intervention of V. ratti and LA increased the abundance of beneficial bacteria, such as Akkermansia, while reducing the abundance of harmful bacteria, such as Escherichia-Shigella and Desulfovibrio, thereby mitigating excessive inflammation. These findings highlight the enhanced therapeutic effects resulting from the interactions between V. ratti and LA, demonstrating the potential of this combined probiotic approach.

Nrf2-induced miR-23a-27a-24-2 cluster modulates damage repair of intestinal mucosa by targeting the Bach1/HO-1 axis in inflammatory bowel diseases

IBD is an idiopathic, chronic autoimmune disease associated with intense oxidative stress. As a master modulator of oxidative stress, Nrf2 has an important anti-inflammatory role in colitis by activating HO-1 transcription. Meanwhile, HO-1 expression is transcriptionally suppressed by Bach1. The Nrf2-activated HO-1 transcription depends on the inactivation of Bach1. However, how Bach1 is inactivated and how Nrf2, Bach1 and HO-1 participate in IBD remains elusive. We found that in response to inflammatory stimuli, Nrf2-induced transcription of miR-23a-27a-24-2 cluster directly inhibits Bach1 expression by binding to the 3'UTR and thereby relieved the Bach1-mediated suppression of HO-1. Besides, elevated miR-23a, miR-27a and miR-24-2 promotes the proliferation and wound healing through regulating Bach1/HO-1 expression in SW480 cell. Additionally, miR-23a, miR-27a and miR-24-2 exert a protective effect on the intestinal mucosa in DSS-induced colitis mouse model. In conclusion, our study revealed that the Nrf2/miR-23a-27a-24-2/Bach1/HO-1 regulatory axis promotes the damage repair of intestinal mucosa during the development of inflammatory bowel diseases.

Oxido-inflammatory responses and histological alterations in rat lungs exposed to petroleum product fumes

Petroleum products-petrol, kerosene, and diesel-composed of volatile organic constituents contribute to air pollution. Exposure of gas station attendants (GSAs) to petroleum products fumes (PPFs) may account for occupation-related predisposition to respiratory toxicity and disease pathogenesis. We simulated GSA exposure to PPF inhalation and examined their effect on oxido-inflammatory responses, toxicity, and histopathological alterations in rat lungs, following 8-hours daily exposure for 60 and 90 days. Reactive oxygen and nitrogen species (RONS), oxidative stress and inflammatory biomarkers, namely: superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione-S-transferase (GST), TNF-α, IL-1β, xanthine oxidase (XO), nitric oxide (NO) activity were evaluated. Besides, histopathological examination of the lungs and trachea of exposed rats, PPF exposure resulted in significant (P < .05) increases in RONS, biomarkers of oxidative stress, pro-inflammation cytokines, and reduced (P < .05) GSH levels in rats, secondary to histopathological alteration in lungs and trachea cytoarchitecture examined in an exposure-duration-dependent manner. We conclude, therefore, that the observed biochemical and histological changes create a microenvironment that is permissive to diseases pathogenesis of the respiratory system via oxido-inflammatory mechanistic pathways.

Tricarbonyldichlororuthenium(II) dimer, the lipid-soluble carbon monoxide-releasing molecule, attenuates Prevotella intermedia lipopolysaccharide-induced production of nitric oxide and interleukin-1β in murine macrophages

Carbon monoxide (CO) is increasingly being appreciated as an important mediator that has pleiotropic biological properties and appears to have a possible therapeutic application for a variety of disorders. Nevertheless, whether this gaseous molecule may be utilized as a therapeutic intervention for periodontal disease is unclear. Here, we examined the potential beneficial effect of CO-releasing molecule-2 (CORM-2), a tricarbonyldichlororuthenium(II) dimer, against the elaboration of proinflammatory mediators by murine macrophages challenged with lipopolysaccharide (LPS) isolated from Prevotella intermedia, a pathogenic bacterium implicated in inflammatory periodontal disease. We found that NO and IL-1β production, iNOS protein expression and mRNA expressions of iNOS and IL-1β were significantly down-regulated when LPS-challenged RAW264.7 cells were exposed to CORM-2. In addition, HO-1 expression was upregulated by CORM-2 in cells activated with P. intermedia LPS, and the inhibitory influence of CORM-2 upon NO production was attenuated by tin protoporphyrin IX, an inhibitor of HO activity. PPAR-γ did not function in the attenuation of NO and IL-1β by CORM-2. JNK and p38 phosphorylation caused by LPS was not altered by CORM-2. CORM-2 reduced NF-κB reporter activity and IκB-α degradation elicited by P. intermedia LPS. Additionally, CORM-2 inhibited LPS-induced phosphorylation of STAT1/3. In conclusion, CORM-2 suppresses NO and IL-1β production caused by P. intermedia LPS. CORM-2 exerts its effect by a mechanism involving anti-inflammatory HO-1 induction and attenuation of NF-κB and STAT1/3 activation, independently of PPAR-γ as well as JNK and p38. CORM-2 may hold promise as host response modulation agent for periodontal disease, though further research is indicated to verify the therapeutic effect.

Oral cadmium exposure affects skin immune reactivity in rats

Skin can acquire cadmium (Cd) by oral route, but there is paucity of data concerning cutaneous effects of this metal. Cd acquired by oral route can affect skin wound healing, but the effect of Cd on other activities involved in skin homeostasis, including skin immunity, are not explored. Using the rat model of 30-day oral administration of Cd (5 ppm and 50 ppm) in drinking water, basic aspects of immune-relevant activity of epidermal cells were examined. Dose-dependent Cd deposition in the the skin was observed (0.035 ± 0.02 µg/g and 0.127 ± 0.04 µg/g at 5 ppm and 50 ppm, respectively, compared to 0.012 ± 0.009 µg/g at 0 ppm of Cd). This resulted in skin inflammation (oxidative stress at both Cd doses and dose-dependent structural changes in the skin and the presence/activation of innate immunity cells). At low Cd dose inflammatory response (nitric oxide and IL-1β) was observed. Other inflammatory cytokines (IL-6 and TNF) response occurred at 50 ppm, which was increased further following skin sensitization with contact allergen dinitro-chlorobenzene (DNCB). Epidermal cells exposed to both Cd doses enhanced concanavalin A (ConA)-stimulated lymphocyte production of IL-17. This study showed for the first time the effect of the metal which gained access to the skin via gut on immune reactivity of epidermal cells. Presented data might be relevant for the link between dietary Cd and the risk of skin pathologies.

LDL dinitrosyl iron complex acts as an iron donor in mouse macrophages

[Fe(NO)₂] - modified nanoparticles of low-density protein (DNICLDL) can serve as conveyors of iron in the form of stable complexes with ApoB100 protein. As reported recently, in human hepatoma cells DNICLDL significantly increased the total iron content, while showing low toxicity. In the present work, we focused on the effects of internalization of DNIC-modified lipoproteins in macrophages, with special regards to cytotoxicity. DNICLDL was administered to a model macrophage cell line, RAW 264.7. Administration of DNICLDL considerably increased total iron content. High increase of iron was accompanied by moderate toxicity. As shown by in vitro plasmid nicking assay, chelation of iron in the form of DNIC strongly reduced the iron-related reactive oxygen species (ROS) -induced DNA damage. In addition, DNICLDL, plausibly due to its NO-donating activity, did not induce inducible nitric oxide synthase (iNOS) expression, as opposed to other forms of low-density protein (LDL).

Systemic effect of mineral aggregate-based cements: histopathological analysis in rats

Objective:

Several studies reported the local tissue reaction caused by mineral aggregate-based cements. However, few studies have investigated the systemic effects promoted by these cements on liver and kidney when directly applied to connective tissue. The purpose of this in vivo study was to investigate the systemic effect of mineral aggregate-based cements on the livers and kidneys of rats.

Material and Methods:

Samples of Mineral Trioxide Aggregate (MTA) and a calcium aluminate-based cement (EndoBinder) containing different radiopacifiers were implanted into the dorsum of 40 rats. After 7 and 30 d, samples of subcutaneous, liver and kidney tissues were submitted to histopathological analysis. A score (0-3) was used to grade the inflammatory reaction. Blood samples were collected to evaluate changes in hepatic and renal functions of animals.

Results:

The moderate inflammatory reaction (2) observed for 7 d in the subcutaneous tissue decreased with time for all cements. The thickness of inflammatory capsules also presented a significant decrease with time (P<.05). Systemically, all cements caused adverse inflammatory reactions in the liver and kidney, being more evident for MTA, persisting until the end of the analysis. Liver functions increased significantly for MTA during 30 d (P<.05).

Conclusion:

The different cements induced to a locally limited inflammatory reaction. However, from the systemic point of view, the cements promoted significant inflammatory reactions in the liver and kidney. For MTA, the reactions were more accentuated.

Taurine reverses sodium fluoride-mediated increase in inflammation, caspase-3 activity, and oxidative damage along the brain-pituitary-gonadal axis in male rats

Excessive exposure to fluoride is associated with male reproductive dysfunction in humans and animals. Taurine (2-aminoethane sulfonic acid) is a free intracellular β-amino acid with antioxidant, anti-inflammatory, and neuroprotective properties. However, the effect of taurine on fluoride-induced reproductive toxicity has not been reported. The present study investigated the influence of taurine on sodium fluoride (NaF)-induced functional changes along the brain-pituitary-gonadal axis in male rats. NaF was administered singly in drinking water at 15 mg·L^-1 alone or orally co-administered by gavage with taurine at 100 and 200 mg·(kg body mass)^-1 for 45 consecutive days. Results showed that taurine significantly prevented NaF-induced increase in oxidative stress indices as well as augmented antioxidant enzymes activities and glutathione level in the brain, testes, and epididymis of the treated rats. Moreover, taurine reversed NaF-induced elevation in inflammatory biomarkers and caspase-3 activity as well as histological damage in the brain, testes, and epididymis of the treated rats. The significant reversal of NaF-induced decreases in testosterone level and testicular activities of acid phosphatase, alkaline phosphatase, and lactate dehydrogenase by taurine was accompanied by enhancement of sperm functional characteristics in the treated rats. Taurine may be a possible chemopreventive candidate against reproductive dysfunction resulting from fluoride exposure.

Heme-oxygenase-1 Production by Intestinal CX3CR1+ Macrophages Helps to Resolve Inflammation and Prevents Carcinogenesis

CX3CR1⁺ macrophages in the intestinal lamina propria contribute to gut homeostasis through the immunomodulatory interleukin IL10, but there is little knowledge on how these cells or the CX3CR1 receptor may affect colorectal carcinogenesis. In this study, we show that CX3CR1-deficient mice fail to resolve gut inflammation despite high production of IL10 and have increased colitis and adenomatous polyps in chemical and genetic models of colon carcinogenesis. Mechanistically, CX3CL1-mediated engagement of the CX3CR1 receptor induced upregulation of heme-oxygenase-1 (HMOX-1), an antioxidant and anti-inflammatory enzyme. CX3CR1-deficient mice exhibited significantly lower expression of HMOX-1 in their adenomatous colon tissues. Combining LPS and CX3CL1 displayed a strong synergistic effect in vitro, but HMOX-1 levels were significantly lower in KO macrophages. Cohousing of wild-type and CX3CR1^-/- mice during the AOM/DSS treatment attenuated disease severity in CX3CR1^-/- mice, indicating the importance of the microbiome, but did not fully reinstate HMOX-1 levels and did not abolish polyp formation. In contrast, pharmacologic induction of HMOX-1 in vivo by cobalt protoporphyrin-IX treatment eradicated intestinal inflammation and fully protected KO mice from carcinogenesis. Taken together, our results establish an essential role for the receptor CX3CR1 in gut macrophages in resolving inflammation in the intestine, where it helps protects against colitis-associated cancer by regulating HMOX-1 expression. Cancer Res; 77(16); 4472-85. ©2017 AACR.

Cytotoxicity of New Calcium Aluminate Cement (EndoBinder) Containing Different Radiopacifiers

Abstract This study aimed to evaluate the cytotoxicity of a calcium aluminate cement (EndoBinder) containing different radiopacifiers, Bi2O3, ZnO or ZrO2, compared with Mineral Trioxide Aggregate (MTA). According to ISO 10993-12:2012 (E) recommendations, 0.2 g of each cement were applied in transwell inserts and placed in 24-well culture plates containing 1 mL of culture medium (DMEM). After 24 h of incubation, the extracts (DMEM containing components released from the cements) were applied to immortalized odontoblast-like MDPC-23 cells. Cell viability (MTT test), alkaline phosphatase activity (ALP), total protein production and cell morphology (Scanning Electron Microscopy - SEM) were evaluated. The volume of 50 µL of extract was used to determine the chemical elements released by the cements using Energy Dispersive Spectroscopy (EDS). The following groups were established (n=6): NC - negative control (without treatment); EB - EndoBinder without radiopacifier; EBBO - EndoBinder+Bi2O3; EBZnO - EndoBinder+ZnO; EBZrO - EndoBinder+ZrO2 and WMTA - White MTA. Data were subjected to statistical analysis (Kruskal-Wallis test, level of significance=5%). Cells exposed to the different versions of EndoBinder presented small reduction in viability, total protein production and ALP activity, with values similar to the NC and WMTA groups (p>0.05). Different elements (C, O, Na, Al, P, Si, Cl, Bi, K) released by the cements were detected in the extracts. However, the cells had no significant changes in their morphology. EndoBinder and MTA did not affect negatively the metabolism of the odontoblastic-like cells, showing it to be cytocompatible, irrespective of the used radiopacifier.

Low Concentration of Exogenous Carbon Monoxide Modulates Radiation-Induced Bystander Effect in Mammalian Cell Cluster Model

During radiotherapy procedures, radiation-induced bystander effect (RIBE) can potentially lead to genetic hazards to normal tissues surrounding the targeted regions. Previous studies showed that RIBE intensities in cell cluster models were much higher than those in monolayer cultured cell models. On the other hand, low-concentration carbon monoxide (CO) was previously shown to exert biological functions via binding to the heme domain of proteins and then modulating various signaling pathways. In relation, our previous studies showed that exogenous CO generated by the CO releasing molecule, tricarbonyldichlororuthenium (CORM-2), at a relatively low concentration (20 µM), effectively attenuated the formation of RIBE-induced DNA double-strand breaks (DSB) and micronucleus (MN). In the present work, we further investigated the capability of a low concentration of exogenous CO (CORM-2) of attenuating or inhibiting RIBE in a mixed-cell cluster model. Our results showed that CO (CORM-2) with a low concentration of 30 µM could effectively suppress RIBE-induced DSB (p53 binding protein 1, p53BP1), MN formation and cell proliferation in bystander cells but not irradiated cells via modulating the inducible nitric oxide synthase (iNOS) andcyclooxygenase-2 (COX-2). The results can help mitigate RIBE-induced hazards during radiotherapy procedures.

Nitric oxide suppresses LPS-induced inflammation in a mouse asthma model by attenuating the interaction of IKK and Hsp90

A feature of allergic airway disease is the observed increase of nitric oxide (NO) in exhaled breath. Gram-negative bacterial infections have also been linked with asthma exacerbations. However, the role of NO in asthma exacerbations with gram-negative bacterial infections is still unclear. In this study, we examined the role of NO in lipopolysaccharide (LPS)-induced inflammation in an ovalbumin (OVA)-challenged mouse asthma model. To determine whether NO affected the LPS-induced response, a NO donor (S-nitroso-N-acetylpenicillamine, SNAP) or a selective inhibitor of NO synthase (1400W) was injected intraperitoneally into the mice before the LPS stimulation. Decreased levels of proinflammatory cytokines were demonstrated in the bronchoalveolar lavage fluid from mice treated with SNAP, whereas increased levels of cytokines were found in the 1400W-treated mice. To further explore the molecular mechanism of NO-mediated inhibition of proinflammatory responses in macrophages, RAW 264.7 cells were treated with 1400W or SNAP before LPS stimulation. LPS-induced inflammation in the cells was attenuated by the presence of NO. The LPS-induced IκB kinase (IKK) activation and the expression of IKK were reduced by NO through attenuation of the interaction between Hsp90 and IKK in the cells. The IKK decrease in the lung immunohistopathology was verified in SNAP-treated asthma mice, whereas IKK increased in the 1400W-treated group. We report for the first time that NO attenuates the interaction between Hsp90 and IKK, decreasing the stability of IKK and causing the down-regulation of the proinflammatory response. Furthermore, the results suggest that NO may repress LPS-stimulated innate immunity to promote pulmonary bacterial infection in asthma patients.

Protective effects of blueberries (Vaccinium corymbosum L.) extract against cadmium-induced hepatotoxicity in mice

The oxidative status and morphological changes of mouse liver exposed to cadmium chloride (Cd(II)) and therapeutic potential of blueberry (Vaccinium corymbosum L.) extract against Cd(II)-induced hepatic injury were investigated. A variety of parameters were evaluated, including lipid peroxidation (LPO), protein carbonyl (PCO) level, DNA fragment, as well as antioxidative defense system (i.e., superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH)). Elemental analysis and evaluation of morphological changes and NO levels were also performed. Exposure to Cd(II) led to increased LPO and PCO as well as DNA fragment and a reduction of SOD and CAT activities, however, the content of GSH elevated probably due to biological adaptive-response. In contrast, co-treatment of anthocyanin (Ay) inhibited the increased oxidative parameters as well as restored the activities of antioxidative defense system in a dose-dependent manner. Ay administration regained these morphological changes caused by intoxication of Cd(II) to nearly normal levels. Moreover, the accumulation of Cd(II) in liver may be one of the reasons for Cd(II) toxicity and Ay can chelate with Cd(II) to reduce Cd(II) burden. The influence of Cd(II) on the Zn and Ca levels can also be adjusted by the co-administration of Ay. Exposure to Cd(II) led to an increase of NO and Ay reduced NO contents probably by directly scavenging. Potential mechanisms for the protective effect of Ay have been proposed, including its anti-oxidative and anti-inflammatory effect along with the metal-chelating capacity. These results suggest that blueberry extract may be valuable as a therapeutic agent in combating Cd(II)-induced tissue injury.

Low concentration of exogenous carbon monoxide protects mammalian cells against proliferation induced by radiation-induced bystander effect

Radiation-induced bystander effect (RIBE) has been proposed to have tight relationship with the irradiation-caused secondary cancers beyond the irradiation-treated area after radiotherapy. Our previous studies demonstrated a protective effect of low concentration carbon monoxide (CO) on the genotoxicity of RIBE after α-particle irradiation. In the present work, a significant inhibitory effect of low-dose exogenous CO, generated by tricarbonyldichlororuthenium (II) dimer [CO-releasing molecule (CORM-2)], on both RIBE-induced proliferation and chromosome aberration was observed. Further studies on the mechanism revealed that the transforming growth factor β1/nitric oxide (NO) signaling pathway, which mediated RIBE signaling transduction, could be modulated by CO involved in the protective effects. Considering the potential of exogenous CO in clinical applications and its protective effect on RIBE, the present work aims to provide a foundation for potential application of CO in radiotherapy.

Glucocorticoids downregulate systemic nitric oxide synthesis and counteract overexpression of hepatic heme oxygenase-1 during endotoxin tolerance

Heme oxygenase (HO)-1 has antioxidant and cytoprotective properties if properly expressed, whereas nitric oxide (NO) impairs tissue perfusion when greatly increased in the blood circulation. Here we hypothesized that the NO and HO-1 systems are altered during lipopolysaccharide (LPS) tolerance, and that glucocorticoids are crucial modulators of systemic NO production and hepatic HO-1 expression during this intriguing phenomenon of cellular reprogramming. Adrenalectomized (ADX) rats with or without administration of dexamethasone (DEX) were challenged with LPS for 3 consecutive days. The plasma levels of corticosterone and nitrate (NOx), and expression of HO-1 protein were assessed. During tolerance, corticosterone levels were elevated, NOx reduced, and HO-1 overexpressed. ADX rats challenged with LPS for 3 consecutive days exhibited a ∼9-fold increase in NOx and a ∼6-fold increase in HO-1, reverted by DEX. Our findings strongly support the fact that glucocorticoids downregulate systemic NO synthesis and counteract hepatic HO-1 overexpression during LPS tolerance.

Mechanism of the protective action of taurine in toxin and drug induced organ pathophysiology and diabetic complications: a review

Taurine (2-aminoethanesulfonic acid), a conditionally essential amino acid, is found in large concentrations in all mammalian tissues and is particularly abundant in aquatic foods. Taurine exhibits membrane stabilizing, osmoregulatory and cytoprotective effects, antioxidative properties, regulates intracellular Ca(2+) concentration, modulates ion movement and neurotransmitters, reduce the levels of pro-inflammatory cytokines in various organs and controls blood pressure. Recently, emerging evidence from the literature shows the effectiveness of taurine as a protective agent against several environmental toxins and drug-induced multiple organ injuries as the outcome of hepatotoxicity, nephrotoxicity, neurotoxicity, testicular toxicity and cardiotoxicity in several animal models. Besides, taurine is also effective in combating diabetes and its associated complications, including cardiomyopathy, nephropathy, neuropathy, retinopathy and atherosclerosis. These beneficial effects appear to be due to the multiple actions of taurine on cellular functions. This review summarizes the mechanism of the prophylactic role of taurine against several environmental toxins and drug-induced organ pathophysiology and diabetes.

Oral bismuth for chronic intractable diarrheal conditions?

Objective

Bismuth has antidiarrheal, antibacterial, and anti-inflammatory properties. We report our single-center experience with oral colloidal bismuth subcitrate (CBS) treatment for patients with chronic intractable diarrhea.

Method

We interrogated our web-based Inflammatory Bowel Disease Clinical and Research database to ascertain clinical details on all patients in our tertiary hospital gastroenterology service treated with CBS between 2000 and 2010. Treatment responses were based on prospective scoring of daily number of liquid stools. Responses were recorded prior to commencement of CBS and at follow-up visits over 12 months.

Results

Thirty-one patients, mean age 47 years (range 17–79 years) and a mean duration of diarrhea of 22 weeks (range 6–104 weeks), were prescribed CBS at doses ranging from 120 mg to 480 mg/day for ≥1 month. Of these, 23 patients (74%) had an initial clinical response and 12 (39%) who continued with this treatment had a sustained clinical response at 1 year. Twelve patients with pouchitis and four patients with indeterminate colitis had initial responses of 92% and 75%, respectively, and sustained responses of 50% and 75%, respectively. Ulcerative colitis patients (n = 5) responded poorly with respect to both initial and sustained responses. Three patients with microscopic colitis showed encouraging initial response of 100% but did not have any sustained benefit. Three of four patients with diarrhea-predominant irritable bowel syndrome (dIBS) had an initial response and two (50%) had good sustained responses. There were no serious adverse events. One patient stopped therapy because of nausea.

Conclusion

This is the largest report of oral bismuth treatment in chronic intractable diarrhea. CBS is cheap and appears to have the potential to be effective for ameliorating diarrheal symptoms in indeterminate colitis, pouchitis, and dIBS. An appropriately powered, blinded, randomized, controlled study appears warranted to establish the position of oral bismuth in routine practice.

Heme oxygenase-1 system and gastrointestinal inflammation: A short review

Heme oxygenase-1 (HO-1) system catalyzes heme to biologically active products: carbon monoxide, biliverdin/bilirubin and free iron. It is involved in maintaining cellular homeostasis and many physiological and pathophysiological processes. A growing body of evidence indicates that HO-1 activation may play an important protective role in acute and chronic inflammation of gastrointestinal tract. This review focuses on the current understanding of the physiological significance of HO-1 induction and its possible roles in the gastrointestinal inflammation studied to date. The ability to upregulate HO-1 by pharmacological means or using gene therapy may offer therapeutic strategies for gastrointestinal inflammation in the future.

In vitro antibacterial activity and cytocompatibility of bismuth doped micro-arc oxidized titanium

Chemical manipulations of the implant surface produce a bactericidal feature to prevent infections around dental implants. Despite the successful use of bismuth against mucosal and dermis infections, the antibacterial effect of bismuth in the oral cavity remains under investigation. The aim of this study was to evaluate the antibacterial activities of bismuth compounds against Actinobacillus actinomycetemcomitans, Staphylococcus mutans, and methicillin-resistant Staphylococcus aureus (MRSA), and to investigate the antimicrobial effects of bismuth doped micro-arc oxidation (MAO) titanium via an agar diffusion test. Cell viability, alkaline phosphatase activity, and mineralization level of MG63 osteoblast-like cells seeded on the coatings were evaluated at 1, 7, and 14 days. The results demonstrate that bismuth nitrate possess superior antibacterial activity when compared with bismuth acetate, bismuth subgallate, and silver nitrate. The bismuth doped MAO coating (contained 6.2 atomic percentage bismuth) had good biological affinities to the MG63 cells and showed a higher antibacterial efficacy against Actinobacillus actinomycetemcomitans and MRSA, where the reduction rates of colony numbers is higher than that of the control group by 1.5 and 1.9 times, respectively. These in vitro evaluations demonstrate that titanium implants with bismuth on the surface may be useful for better infection control.

Nitric oxide-supplemented resuscitation improves early gastrointestinal blood flow in rats subjected to hemorrhagic shock without late consequences

BACKGROUND

we have shown that hemorrhage/resuscitation altered gastrointestinal blood flow (GI-BF) and that gastric perfusion did not recover after resuscitation. This study aimed to determine the effect of nitric oxide (NO) supplemented resuscitation on the mean arterial blood pressure (MAP), GI-BF, and outcome after hemorrhagic shock.

METHODS

rats were subjected to hemorrhage and resuscitation with/without the NO-donor S-nitroso human serum albumin (S-NO-HSA). GI-BF was determined using colored microspheres.

RESULTS

NO supplementation significantly decreased MAP at the end of resuscitation. At the same time point, the GI-BF has significantly increased in the stomach, duodenum, and colon. Two hours after treatment discontinuation, there was no difference in either MAP or GI-BF between NO-supplemented and control groups. The survival times indicated that S-NO-HSA treatment was noninferior compared with control.

CONCLUSIONS

NO-supplemented resuscitation improves the GI-BF during the early stage of resuscitation without a negative impact on short-/long-term survival despite a transient MAP decrease.

Salbutamol inhibits lipopolysaccharide-induced inflammatory responses in rat peritoneal macrophages

Acute and chronic inflammatory diseases are associated with the induction of inducible nitric oxide synthase (iNOS) and inducible heme oxygenase (HO-1). These inducible enzymes are up-regulated in macrophages subjected to inflammatory stimuli and oxidative stress. beta(2)-Adrenoceptor (AR) agonists, which function as bronchial dilators, are widely used for the treatment of asthma and chronic obstructive pulmonary disease (COPD). We examined whether salbutamol, a classical beta(2)-AR agonist, inhibits the induction of proinflammatory cytokines and stress inducible proteins. Rat macrophages obtained from the abdominal cavity were incubated with lipopolysaccharide (LPS) with or without salbutamol. Induction by LPS of tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 was significantly inhibited (P < 0.05) by salbutamol treatment. Induction by LPS of iNOS mRNA and protein was also significantly inhibited (P < 0.05) by salbutamol. LPS-mediated increases in HO-1 mRNA and protein were not appreciably affected by salbutamol. One of the anti-inflammatory mechanisms of salbutamol was thus found to be inhibition of induction by LPS of extracellular stimulus-responsive kinase (ERK) 1/2 in macrophages. These findings suggest that salbutamol has the potential for use as an anti-inflammatory agent due to its suppression of LPS-induced TNF-alpha, and IL-6 and iNOS via ERK pathway without affecting HO-1 expression.

Hemin inhibits NO production by IL-1β-stimulated human astrocytes through induction of heme oxygenase-1 and reduction of p38 MAPK activation

Background

Heme oxygenase (HO)-1 has been shown to attenuate oxidative injury and reduce apoptosis. HO-1 can be induced by various stimuli released during cellular injury, such as heme. Deleterious free heme is degraded by HO-1 to carbon monoxide, iron and biliverdin, which have potent anti-oxidant and anti-inflammatory properties. In this study, we tested the hypothesis that upregulation of HO-1 would inhibit production of the free radical (NO) by interlukin (IL)-1β-activated human astrocytes.

Methods

To measure NO production, inducible NO synthase (iNOS), HO-1 expression and mitogen-activated protein (MAP) kinase activation we used hemin as an HO-1 inducer and tin protoporphyrin (SnPP) IX as an inhibitor of HO-1 activity in human astrocyte cultures prior to IL-1β exposure. Transfection of astrocyte cultures was performed using a pLEX expression vector carrying the human HO-1 sequence prior to IL-1β treatment. Supernatants of astrocyte cultures pretreated with inhibitors of p38 MAPK or MEK1/2 prior to IL-1β exposure were collected for NO assay.

Results

IL-1β treatment of astrocytes alone induced undetectable amounts of HO-1 protein by western blot. However, HO-1 mRNA expression was modestly up-regulated in response to IL-1β stimulation. Pretreatment with hemin alone substantially induced both HO-1 mRNA and protein expression, and HO-1 mRNA expression was further enhanced when hemin was combined with IL-1β treatment. In contrast, IL-1β-induced iNOS mRNA expression and NO production were markedly inhibited by hemin treatment. When pretreated with SnPP, the inhibitory effect of hemin on IL-1β-induced NO production and iNOS expression was reversed, suggesting the involvement of HO-1. IL-1β-induced p38 MAPK activation, which is known to be required for NO production, was also down-regulated by hemin.

Conclusion

These findings support the hypothesis that up-regulation of HO-1 in astrocytes is associated with down-regulation of iNOS expression and thereby NO production, an effect that involves the p38 MAPK signaling pathway, which suggests that this glial cell response could play an important protective role against oxidative stress in the brain.

Potential for amino acids supplementation during inflammatory bowel diseases

The pathophysiology of inflammatory bowel diseases (IBDs) is multifactorial and involves interactions of gut luminal content with mucosal barrier and especially immune cells. Malnutrition is a frequent issue during IBD flares, especially in Crohn's disease (CD) patients, and nutritional support is frequently used to treat malnutrition but also in an attempt to modulate intestinal inflammation. The use of oral or enteral nutrition intervention in IBDs may be effective, alone or in combination with drugs, to achieve and maintain remission. However, standard diets are less effective than new-generation biotherapies and could be improved by supplementation with specific immunomodulatory amino acids. Experimental studies evaluating glutamine, the preferential substrate for enterocytes, are promising. Some clinical studies with oral glutamine in CD are until now disappointing, but new formulations and targeting could enhance glutamine efficacy at the site of mucosal lesions. The role of arginine, involved in nitric oxide and polyamines synthesis, still remains debated. However, the effects of these amino acids in IBD have been poorly documented in humans. Other candidates like glycine, cysteine, histidine, or taurine should also be evaluated in the future.

Exogenous carbon monoxide protects the bystander Chinese hamster ovary cells in mixed coculture system after alpha-particle irradiation

In the present work, the inhibitory effect of carbon monoxide (CO), generated by tricarbonyldichlororuthenium (II) dimer [CO-releasing molecule (CORM-2)], on the toxicity of radiation-induced bystander effect (RIBE) after alpha-particle irradiation was studied in a mixed coculture system. CO (CORM-2) treatment showed a significant inhibitory effect to the formation of p53 binding protein 1 (BP1) and micronuclei (MN) induced by RIBE in a concentration-dependent manner, but in the directly irradiated cell population no distinct decreases of BP1 and MN formation were observed. In this mixed coculture system, nitric oxide (NO) or superoxide anion (O2(*-)) was also proved to mediate the transduction of RIBE by using a NO synthase inhibitor or NADPH-oxidase-specific inhibitor treatment. The elevated O2(*-) was attenuated by CO (CORM-2) treatment in the bystander cells as measured by hydroethidine staining and fluorescence assessment. The exogenous NO (sper) or O2(*-) (H2O2) was used to mimic NO/O(2)-mediated RIBE, and CO (CORM-2) treatment also showed a protective effect to cells against the toxicity of these exogenous factors. Considering the inhibitory effect of CO on RIBE and the wide use of CO in therapy of diseases, it is hoped that a low concentration of CO can protect normal tissues against RIBE during radiotherapy.

Impairment of endothelium-dependent vasorelaxation in cadmium-hypertensive rats

Abnormalities in the production and/or release of relaxing factors from the endothelium have been implicated in the development of hypertension in several animal models. Endothelium-dependent relaxation has been reported to be impaired in thoracic aorta in experimentally induced and genetically hypertensive rats. Present study has extented these observations to thoracic aorta of cadmium-hypertensive rats. The possible role of alterations in oxidant status was also studied. Hypertension was induced by the intraperitoneal administration of 1 mg/kg/day cadmium for 15 days. Mechanical responses produced by acetylcholine (ACh, 10— 9—10—4 M) and sodium nitroprusside (SNP, 10—10—10— 5 M) were studied on phenylephrine-precontracted thoracic aorta rings from control and cadmium-hypertensive rats. Serum nitric oxide (NO) and aortic malondialdehyde (MDA) levels were measured. ACh-induced relaxation was attenuated in aorta from cadmium-hypertensive rats, whereas relaxation responses to SNP did not differ significantly between the groups. Exposure of aortic rings to NG-nitro-L-arginine methyl ester (L-NAME, 10 —4 M) resulted in a significantly greater inhibition of relaxation response to ACh in aortic rings of cadmium-hypertensive rats as compared with control rats. Incubation with L-arginine (L-Arg, 10 —3 M) caused a similar reversal of the inhibition of ACh-induced relaxation by L-NAME in both groups. Serum NO levels were decreased and aortic MDA levels were increased in cadmium-treated rats as compared with control rats. However, the differences between the groups did not reach a statistical significance. These findings suggested that the reduction in endothelium-dependent relaxation may play a role in cadmium-induced hypertension as it was in many other hypertension models.

iNOS expression in oral and gastrointestinal tract mucosa

It is known that the overproduction of nitric oxide (NO) by nitric oxide synthase (NOS) occurs during the progression of various inflammatory diseases in intestinal tract. NOS inhibitors or inducible nitric oxide synthase (iNOS) gene expression inhibitors should be considered as potential anti-inflammatory agents, as NO synthesized by iNOS is related to various pathophysiological processes including inflammation. In order to understand the relationship between iNOS and pathological reactions such as the inflammatory process and malign transformation clearly, the existence and amount of constitutive expression should be determined. It is crucial to comprehend the harmful and protective amounts of iNOS expressions in order to clarify the relationship between iNOS and pathological processes. Evidently, only after this inspection is it possible to utilize iNOS as a marker and treatment instrument during the diagnosis and treatment of malign transformation and the inflammatory process.

Lentivirus mediated HO-1 gene transfer enhances myogenic precursor cell survival after autologous transplantation in pig

Cell therapy for Duchenne muscular dystrophy and other muscle diseases is limited by a massive early cell death following injections. In this study, we explored the potential benefit of heme oxygenase-1 (HO-1) expression in the survival of porcine myogenic precursor cells (MPCs) transplanted in pig skeletal muscle. Increased HO-1 expression was assessed either by transient hyperthermia or by HO-1 lentiviral infection. One day after the thermic shock, we observed a fourfold and a threefold increase in HSP70/72 and HO-1 levels, respectively. This treatment protected 30% of cells from staurosporine-induced apoptosis in vitro. When porcine MPC were heat-shocked prior to grafting, we improved cell survival by threefold at 5 days after autologous transplantation (26.3 +/- 5.5% surviving cells). After HO-1 lentiviral transduction, almost 60% of cells expressed the transgene and kept their myogenic properties to proliferate and fuse in vitro. Apoptosis of HO-1 transduced cells was reduced by 50% in vitro after staurosporine induction. Finally, a fivefold enhancement in cell survival was observed after transplantation of HO-1-group (47.5 +/- 9.1% surviving cells) as compared to the nls-LacZ-group or control group. These results identify HO-1 as a protective gene against early MPC death post-transplantation.

Exhaled carbon monoxide concentration is not elevated in patients with inflammatory bowel disease

The present study was initiated to examine whether the concentration of CO in the breath is elevated in patients with inflammatory bowel disease (IBD). Twenty-three clinically stable patients with IBD in the outpatient clinic (11 with Crohn's disease, 12 with ulcerative colitis), who are non-smokers and non-passive smokers, were selected and the concentration of CO in their breath was measured using a breath gas analyser (TRI lyser mBA-3000). The concentration of CO in the breath of 23 patients with IBD was 2.5+/-0.9 (1.1-4.3) ppm. This concentration comes within the range of standard values in our previous reports (2.5+/-2.2 ppm). Any significant difference was not observed between 2.4+/-0.9 (1.5-4.3) ppm for the 11 Crohn's disease patients and the 2.6+/-1.0 (1.1-3.9) ppm for the 12 ulcerative colitis patients. The results suggest that clinically stable patients with IBD do not show high values for concentration of CO in the breath.

ADOA3R as a therapeutic target in experimental colitis: proof by validated high-density oligonucleotide microarray analysis

Adenosine A3 receptors (ADOA3Rs) are emerging as novel purinergic targets for treatment of inflammatory diseases. Our goal was to assess the protective effect of the ADOA3R agonist N(6)-(3-iodobenzyl)-adenosine-5-N-methyluronamide (IB-MECA) on gene dysregulation and injury in a rat chronic model of 2,4,6-trinitrobenzene sulfonic acid (TNBS)--induced colitis. It was necessary to develop and validate a microarray technique for testing the protective effects of purine-based drugs in experimental inflammatory bowel disease. High-density oligonucleotide microarray analysis of gene dysregulation was assessed in colons from normal, TNBS-treated (7 days), and oral IB-MECA-treated rats (1.5 mg/kg b.i.d.) using a rat RNU34 neural GeneChip of 724 genes and SYBR green polymerase chain reaction. Analysis included clinical evaluation, weight loss assessment, and electron paramagnetic resonance imaging/spin-trap monitoring of free radicals. Remarkable colitis-induced gene dysregulation occurs in the most exceptional cluster of 5.4% of the gene pool, revealing 2 modes of colitis-related dysregulation. Downregulation occurs in membrane transporter, mitogen-activated protein (MAP) kinase, and channel genes. Upregulation occurs in chemokine, cytokine/inflammatory, stress, growth factor, intracellular signaling, receptor, heat shock protein, retinoid metabolism, neural, remodeling, and redox-sensitive genes. Oral IB-MECA prevented dysregulation in 92% of these genes, histopathology, gut injury, and weight loss. IB-MECA or adenosine suppressed elevated free radicals in ex vivo inflamed gut. Oral IB-MECA blocked the colitis-induced upregulation (<or=20-fold) of Bzrp, P2X1R, P2X4R, P2X7R, P2Y2R, P2Y6R, and A2aR/A2bR but not A1R or A3R genes or downregulated P2X2R, P2Y1R, and P2Y4R. Real-time SYBR green polymerase chain reaction validated gene chip data for both induction of colitis and treatment with IB-MECA for >90% of genes tested (33 of 37 genes). We conclude that our validated high-density oligonucleotide microarray analysis is a powerful technique for molecular gene dysregulation studies to assess the beneficial effects of purine-based or other drugs in experimental colitis. ADOA3R is new potential therapeutic target for inflammatory bowel disease.

Heme in intestinal epithelial cell turnover, differentiation, detoxification, inflammation, carcinogenesis, absorption and motility

The gastrointestinal tract is lined by a simple epithelium that undergoes constant renewal involving cell division, differentiation and cell death. In addition, the epithelial lining separates the hostile processes of digestion and absorption that occur in the intestinal lumen from the aseptic environment of the internal milieu by defensive mechanisms that protect the epithelium from being breached. Central to these defensive processes is the synthesis of heme and its catabolism by heme oxygenase (HO). Dietary heme is also an important source of iron for the body which is taken up intact by the enterocyte. This review describes the recent literature on the diverse properties of heme/HO in the intestine tract. The roles of heme/HO in the regulation of the cell cycle/apoptosis, detoxification of xenobiotics, oxidative stress, inflammation, development of colon cancer, heme-iron absorption and intestinal motility are specifically examined.

Caffeic acid phenethyl ester prevents cadmium-induced cardiac impairment in rat

Caffeic acid phenethyl ester (CAPE), a flavonoid like compound, is one of the major components of honeybee propolis. It was found to be a potent free radical scavenger and antioxidant recently. The aim of this study was to examine the effect of CAPE on cadmium (Cd)-induced hypertension and cardiomyopathy in rats. In particular, nitric oxide (NO) may contribute to the pathophysiology of Cd induced cardiac impairment. Malondialdehyde (MDA, an index of lipid peroxidation) levels and nitric oxide (NO, a vasodilator) levels were used as markers Cd-induced cardiac impairment and the success of CAPE treatment. Also, the findings have been supported by the histopathologic evidences. The rats were randomly divided into three experimental groups each (12), as follows: the control group, Cd-treated group (Cd) and Cd plus CAPE-treated group (Cd+CAPE). CdCl(2) in 0.9% NaCl was administrated intraperitoneally (i.p.) with a dose of 1mg/kg/day. CAPE was co-administered i.p. a dose of 10 microM/kg for 15 days. Hypertension was found to be induced by intraperitoneal administration of Cd in a dose of 1mg/kg/day on the measurements taken 15 days later. MDA levels were increased (p<0.001) in cardiac tissue and NO levels were decreased (p<0.05) in serum in the Cd group than those of the control group had. On the other hand, there was a slight difference (increase) in MDA levels in the Cd+CAPE group than the ones in the control group (p<0.003). In addition, MDA levels were decreased and NO levels were increased in the Cd+CAPE group compared with the Cd group (p<0.001, p<0.0001, respectively). As a result, treatment with CAPE significantly reversed the increased lipid peroxidation (LPO) product, MDA, and decreased NO levels in Cd treated animals. In the histopathologic examination, a significant hypertrophy in atrial and ventricular myofibrils was observed in only Cd administered group, in comparison with the control group. There was no statistically significant difference between the CAPE given and control groups by means of atrial and ventricular myofibril diameters. In conclusion, the underlying mechanism of the myocardial hypertrophy may be related to hypertension due to inhibition of NO production in the vessels, and CAPE has a protective effect on Cd-induced hypertension mediated cardiac impairment in the rats.

Carbon Monoxide: Endogenous Production, Physiological Functions, and Pharmacological Applications

Over the last decade, studies have unraveled many aspects of endogenous production and physiological functions of carbon monoxide (CO). The majority of endogenous CO is produced in a reaction catalyzed by the enzyme heme oxygenase (HO). Inducible HO (HO-1) and constitutive HO (HO-2) are mostly recognized for their roles in the oxidation of heme and production of CO and biliverdin, whereas the biological function of the third HO isoform, HO-3, is still unclear. The tissue type-specific distribution of these HO isoforms is largely linked to the specific biological actions of CO on different systems. CO functions as a signaling molecule in the neuronal system, involving the regulation of neurotransmitters and neuropeptide release, learning and memory, and odor response adaptation and many other neuronal activities. The vasorelaxant property and cardiac protection effect of CO have been documented. A plethora of studies have also shown the importance of the roles of CO in the immune, respiratory, reproductive, gastrointestinal, kidney, and liver systems. Our understanding of the cellular and molecular mechanisms that regulate the production and mediate the physiological actions of CO has greatly advanced. Many diseases, including neurodegenerations, hypertension, heart failure, and inflammation, have been linked to the abnormality in CO metabolism and function. Enhancement of endogenous CO production and direct delivery of exogenous CO have found their applications in many health research fields and clinical settings. Future studies will further clarify the gasotransmitter role of CO, provide insight into the pathogenic mechanisms of many CO abnormality-related diseases, and pave the way for innovative preventive and therapeutic strategies based on the physiologic effects of CO.

An integral role for heme oxygenase-1 and carbon monoxide in maintaining peripheral tolerance by CD4+CD25+ regulatory T cells

Over the past decade, a great deal of interest and attention has been directed toward a population of regulatory T cells (Treg) coexpressing the markers CD4 and CD25. The hallmark phenotype of this cell population resides in its ability to dominantly maintain peripheral tolerance and avert autoimmunity. Despite robust research interest in Treg, their mechanism of action and interaction with other cell populations providing immune regulation remains unclear. In this study, we present a model for Treg activity that implicates carbon monoxide, a by-product of heme oxygenase-1 activity, as an important and underappreciated facet in the suppressive capacity of Treg. Our hypothesis is based on recent evidence supporting a role for heme oxygenase-1 in regulating immune reactivity and posit carbon monoxide to function as a suppressive molecule. Potential roles for indoleamine 2,3-dioxygenase, costimulatory molecules, and cytokines in tolerance induction are also presented. This model, if validated, could act as a catalyst for new investigations into Treg function and ultimately result in novel methods to modulate Treg biology toward therapeutic applications.

Heme oxygenase-1-generated biliverdin ameliorates experimental murine colitis

BACKGROUND

Heme oxygenase-1 (HO-1) seems to have an important protective role in acute and chronic inflammation. The products of heme catalysis, biliverdin/bilirubin, carbon monoxide (CO), and iron (that induces apoferritin) mediate the beneficial effects of HO-1. Blockade of HO-1 activity results in exacerbation of experimental colitis. We tested whether HO-1 has protective effects in the development of colitis and determined that specific enzymatic products of HO-1 are responsible for these effects.

METHODS

Colitis was induced by oral administration of dextran sodium sulfate (5%) to C57BL/6 mice for 7 days. HO-1 was up-regulated by cobalt-protoporphyrin (5 mg/kg, intraperitoneally). Biliverdin, exogenous CO, or the iron chelator desferrioxamine was administered to other groups.

RESULTS

Cobalt-protoporphyrin treatment resulted in significant up-regulation of HO-1 protein in mucosal and submucosal cells. Induction of HO-1 was associated with significantly less loss of body weight in mice with induced colitis (-12% versus -22% in the control animals, P < 0.001). Development of diarrhea and gastrointestinal hemorrhage was substantially delayed in animals in which HO-1 was induced, and mucosal injury was significantly attenuated. Administration of CO or desferrioxamine alone had no significant effects, whereas enhanced protection with lesser evidence of bowel inflammation was observed with systemic biliverdin administration (50 micromol/kg, 3 times per day, intraperitoneally).

CONCLUSIONS

We conclude that heightened HO-1 expression or administration of biliverdin ameliorates dextran sodium sulfate-induced experimental colitis. Novel therapeutic strategies based on HO-1 and/or biliverdin administration may have use in inflammatory bowel disease.

Nitric oxide synthase is downregulated, while haem oxygenase is increased, in patients with septic shock

BACKGROUND

The vasodilatation characteristic of human septic shock is conventionally attributed to increased nitric oxide production, primarily by extrapolation of animal and human in vitro studies. There are no conclusive studies of human disease, and the cellular source of nitric oxide in human sepsis is not known. Haem oxygenase is upregulated by oxidative stress, but little is known about haem oxygenase expression in human sepsis. Haem oxygenase may modulate nitric oxide production, and may also have a direct effect on vascular tone.

METHODS

Mesenteric arterial smooth muscle (ASM) (obtained during laparotomy) and peripheral blood mononuclear cells (PBMCs) were obtained from patients with early septic shock and from control patients. mRNA levels were determined by real-time RT-PCR.

RESULTS

mRNA for inducible and endothelial nitric oxide synthase was reduced in both ASM and PBMCs from septic patients. In contrast, inducible haem oxygenase mRNA was increased in sepsis in both cell types.

CONCLUSIONS

These results suggest that, rather than being induced, the enzymes which produce nitric oxide are reduced at this time point in human septic shock. Thus many of the in vitro models of sepsis studied to date may not fully replicate human disease. The increase in haem oxygenase expression confirms that these cells have been subjected to oxidative stress in sepsis. The activity of induced haem oxygenase may limit nitric oxide production, while possibly causing vasodilation through production of carbon monoxide.

Opposite effect of oxidative stress on inducible nitric oxide synthase and haem oxygenase-1 expression in intestinal inflammation: anti-inflammatory effect of carbon monoxide

Inducible nitric oxide synthase (iNOS) is expressed in intestinal epithelial cells (IEC) of patients with active inflammatory bowel disease (IBD) and in IEC of endotoxaemic rats. The induction of iNOS in IEC is an element of the NF-kappaB-mediated survival pathway. Haem oxygenase-1 (HO-1) is an AP-1-regulated gene that is induced by oxidative stress. The enzyme produces carbon monoxide (CO), which may attenuate the inflammatory response. The aim of this study was to investigate the regulation and interaction of iNOS and HO-1 in response to inflammation and oxidative stress. Male Wistar rats were treated with the thiol-modifying agent diethylmaleate (DEM) to induce oxidative stress and rendered endotoxaemic by LPS injection. Human colonic biopsies and the human colon carcinoma cell line DLD-1 were treated with DEM and the lipid peroxidation end-product 4-hydroxynonenal to induce oxidative stress and exposed to cytokine mix (CM) to mimic inflammation. In some experiments, cells were incubated with 250-400 ppm CO prior to and during stimulation with CM. HO-1 and iNOS expression was evaluated by RT-PCR, western blotting, and immunohistology. NF-kappaB activation was evaluated by EMSA. LPS induced iNOS but not HO-1 in epithelial cells of the ileum and colon. Oxidative stress strongly induced HO-1 in epithelial and inflammatory cells. Combined oxidative stress and endotoxaemia decreased iNOS expression but strongly induced HO-1 expression. Similarly, CM induced iNOS but not HO-1 in colonic biopsies and DLD-1 cells. Oxidative stress prevented iNOS induction in an NF-kappaB-dependent manner but increased HO-1 expression in CM-exposed DLD-1 cells. CO inhibited iNOS mRNA induction in CM-stimulated DLD-1 cells. These data demonstrate opposite regulation of iNOS and HO-1 in intestinal epithelial cells in response to cytokine exposure and oxidative stress. These findings suggest that iNOS (NF-kappaB driven) and HO-1 (AP-1 driven) represent mutually exclusive survival mechanisms in intestinal epithelial cells.

Cooperative effect of biliverdin and carbon monoxide on survival of mice in immune-mediated liver injury

Induction of the heme-degrading enzyme heme oxygenase-1 (HO-1) has been shown to be beneficial in terms of improvement of liver allograft survival and prevention of CD95-mediated apoptosis in the liver. In the present study, we investigated the effects of HO-1, and its products carbon monoxide (CO), biliverdin (BV), and iron/ferritin, in a mouse model of inflammatory liver damage inducible by lipopolysaccharide (LPS) in mice sensitized with the hepatocyte-specific transcription inhibitor D-galactosamine (GalN). Our results show that HO-1 induction by cobalt-protoporphyrin-IX (CoPP) reduced cytokine expression, protected mice from liver injury, and prolonged survival. While in contrast to ferritin overexpression, single administration of the CO donor methylene chloride (MC) or of BV also protected mice from liver damage, only coadministration of both HO products prolonged survival and reduced the expression of cytokines, e.g., tumor necrosis factor (TNF) and interferon gamma (IFN-gamma). In conclusion, HO-1-induced prolongation of survival, but not the protection from liver damage, seems to be dependent on down-regulation of cytokine synthesis.

The HIV protease inhibitor ritonavir synergizes with butyrate for induction of apoptotic cell death and mediates expression of heme oxygenase-1 in DLD-1 colon carcinoma cells

The protease inhibitor ritonavir is an integral part of current antiretroviral therapy targeting human immunodeficiency virus. Recent studies demonstrate that ritonavir induces apoptotic cell death with high efficiency in lymphoblastoid cell lines. Moreover, ritonavir can suppress activation of the transcription factor nuclear factor-kappaB and is an inhibitor of interleukin-1beta and tumor necrosis factor-alpha production in peripheral blood mononuclear cells. Thus, ritonavir appears to have anti-inflammatory properties. In the present study, we investigated in DLD-1 colon carcinoma cell effects of ritonavir on apoptotic cell death and expression of heme oxygenase-1 (HO-1), an anti-inflammatory enzyme that may be critically involved in the modulation of colonic inflammation. Compared to unstimulated control, ritonavir resulted in a moderate increase in the rate of apoptotic cell death as observed after 20 h of incubation. Notably, ritonavir potently synergized with the short-chain fatty acid butyrate for induction of caspase-3-dependent apoptosis in DLD-1 cells. Ritonavir enhanced mRNA and protein expression of HO-1 in DLD-1 cells. Ritonavir-induced HO-1 protein was suppressed by SB203580 or SB202190 and preceded by immediate upregulation of cellular c-Fos and c-Jun protein levels. This process was associated with induction of activator protein-1 as detected by electrophoretic mobility shift analysis. The present data suggest that ritonavir has the potential to curb colon carcinogenesis by reducing cell growth via mechanisms that include apoptosis and by simultaneously modulating colonic inflammation via induction of anti-inflammatory HO-1.

Nitric oxide and the gut injury induced by non-steroidal anti-inflammatory drugs

Nitric oxide (NO) can protect the gastrointestinal tract from injury, including that provoked by non-steroidal anti-inflammatory drugs (NSAIDs). This protective profile of NO, which predominantly reflects actions on the microcirculation, is mimicked by NO donors. Moreover, the NO-donating agents know as the NO-NSAIDs or CINODs (cyclo-oxygenase-inhibiting nitric oxide-donating drugs) exhibit reduced gut injury in experimental models, which is considered to reflect these local beneficial actions of NO. NSAIDs cause chronic inflammatory lesions in the small intestine in experimental models. This injury results from initial COX inhibition and other local events, with translocation of indigenous luminal bacteria, leading to induction of NO synthase isoform, iNOS, and subsequent production of the cytotoxic moiety, peroxynitrite from NO and superoxide. Agents that inhibit iNOS or superoxide production can attenuate such intestinal injury. In the absence of reactive oxygen moieties, NO may play a beneficial role in the resolution of inflammatory damage to the gut, thus reconciling the potential opposing properties of NO in tissue inflammation and injury.

Expression of heat shock protein 32 (hemoxygenase-1) in the normal and inflamed human stomach and colon: an immunohistochemical study

Heat shock protein 32 (Hsp32, hemoxygenase-1) is induced by reactive oxygen metabolites (ROM) and degrades heme leading to the formation of antioxidant bilirubin. Increased mucosal generation of ROM occurs in gastritis and inflammatory bowel disease. We aimed to assess mucosal expression of Hsp32 in normal stomach and colon and to test the hypothesis that disease-related differential expression occurs in inflamed tissue. Gastric body and antral mucosal biopsies were obtained from 33 patients comprising Helicobacter pylori-negative normal controls (n = 8), H pylori-negative gastritis patients (n = 11), and H pylori-positive gastritis patients (n = 14). Forty-seven archival colonic mucosal biopsies selected comprised normal histology (n = 10), active ulcerative colitis (UC) (n = 9), inactive UC (n = 8), active Crohn's disease (CD) (n = 8), inactive CD (n = 6), and other colitides (n = 6). Hsp32 expression in formalin-fixed sections was assessed by avidin-biotin peroxidase immunohistochemistry using a polyclonal rabbit anti-Hsp32 as the primary antibody. Immunohistochemical staining identified Hsp32 in all groups. Diffuse cytoplasmic staining was seen in gastric and colonic epithelial and lamina proprial inflammatory cells. Staining scores for Hsp32 were higher in antral H pylori-positive (P = 0.002) and H pylori-negative (P = 0.02) gastritis than in controls and in body H pylori-positive gastritis than in the other 2 groups (P < 0.01). Expression of Hsp32 was increased in active UC compared with inactive disease (P = 0.03) and normal controls (P = 0.02). In conclusion, Hsp32 is expressed constitutively in normal gastric and colonic mucosa, and differential expression occurs in these tissues when they are inflamed. Upregulation of Hsp32 may be an adaptive response to protect mucosa from oxidative injury in patients with gastritis and inflammatory bowel disease.

Expression of heat shock protein 32 (hemoxygenase-1) in the normal and inflamed human stomach and colon: an immunohistochemical study

Heat shock protein 32 (Hsp32, hemoxygenase-1) is induced by reactive oxygen metabolites (ROM) and degrades heme leading to the formation of antioxidant bilirubin. Increased mucosal generation of ROM occurs in gastritis and inflammatory bowel disease. We aimed to assess mucosal expression of Hsp32 in normal stomach and colon and to test the hypothesis that disease-related differential expression occurs in inflamed tissue. Gastric body and antral mucosal biopsies were obtained from 33 patients comprising Helicobacter pylori-negative normal controls (n = 8), H pylori-negative gastritis patients (n = 11), and H pylori-positive gastritis patients (n = 14). Forty-seven archival colonic mucosal biopsies selected comprised normal histology (n = 10), active ulcerative colitis (UC) (n = 9), inactive UC (n = 8), active Crohn's disease (CD) (n = 8), inactive CD (n = 6), and other colitides (n = 6). Hsp32 expression in formalin-fixed sections was assessed by avidin-biotin peroxidase immunohistochemistry using a polyclonal rabbit anti-Hsp32 as the primary antibody. Immunohistochemical staining identified Hsp32 in all groups. Diffuse cytoplasmic staining was seen in gastric and colonic epithelial and lamina proprial inflammatory cells. Staining scores for Hsp32 were higher in antral H pylori-positive (P = 0.002) and H pylori-negative (P = 0.02) gastritis than in controls and in body H pylori-positive gastritis than in the other 2 groups (P < 0.01). Expression of Hsp32 was increased in active UC compared with inactive disease (P = 0.03) and normal controls (P = 0.02). In conclusion, Hsp32 is expressed constitutively in normal gastric and colonic mucosa, and differential expression occurs in these tissues when they are inflamed. Upregulation of Hsp32 may be an adaptive response to protect mucosa from oxidative injury in patients with gastritis and inflammatory bowel disease.

Expression of heat shock protein 32 (hemoxygenase-1) in the normal and inflamed human stomach and colon: an immunohistochemical study

Heat shock protein 32 (Hsp32, hemoxygenase-1) is induced by reactive oxygen metabolites (ROM) and degrades heme leading to the formation of antioxidant bilirubin. Increased mucosal generation of ROM occurs in gastritis and inflammatory bowel disease. We aimed to assess mucosal expression of Hsp32 in normal stomach and colon and to test the hypothesis that disease-related differential expression occurs in inflamed tissue. Gastric body and antral mucosal biopsies were obtained from 33 patients comprising Helicobacter pylori-negative normal controls (n = 8), H pylori-negative gastritis patients (n = 11), and H pylori-positive gastritis patients (n = 14). Forty-seven archival colonic mucosal biopsies selected comprised normal histology (n = 10), active ulcerative colitis (UC) (n = 9), inactive UC (n = 8), active Crohn's disease (CD) (n = 8), inactive CD (n = 6), and other colitides (n = 6). Hsp32 expression in formalin-fixed sections was assessed by avidin-biotin peroxidase immunohistochemistry using a polyclonal rabbit anti-Hsp32 as the primary antibody. Immunohistochemical staining identified Hsp32 in all groups. Diffuse cytoplasmic staining was seen in gastric and colonic epithelial and lamina proprial inflammatory cells. Staining scores for Hsp32 were higher in antral H pylori-positive (P = 0.002) and H pylori-negative (P = 0.02) gastritis than in controls and in body H pylori-positive gastritis than in the other 2 groups (P < 0.01). Expression of Hsp32 was increased in active UC compared with inactive disease (P = 0.03) and normal controls (P = 0.02). In conclusion, Hsp32 is expressed constitutively in normal gastric and colonic mucosa, and differential expression occurs in these tissues when they are inflamed. Upregulation of Hsp32 may be an adaptive response to protect mucosa from oxidative injury in patients with gastritis and inflammatory bowel disease.