Increased Superoxide Dismutase Activity Improves Survival of Cultured Postnatal Midbrain Neurons

Abstract: Copper/zinc superoxide dismutase (Cu/Zn-SOD) is a major free radical scavenging enzyme. Increased Cu/Zn-SOD activity protects cells against oxidative stress mediated by different mechanisms. However, there is also in vitro and in vivo evidence that, in the absence of abnormal oxidative stress, chronic increased Cu/Zn-SOD activity is detrimental to living cells. To address this issue, we examined the fate of mature midbrain neurons from transgenic mice expressing human Cu/Zn-SOD and from their nontransgenic littermates. Midbrain from transgenic pups had about threefold higher Cu/Zn-SOD activity than that from nontransgenic pups. Virtually all transgenic neurons were strongly immunoreactive for human Cu/Zn-SOD protein in their cell bodies and processes. The number of midbrain neurons decreased over time in both transgenic and nontransgenic cultures, but to a significantly smaller extent in the transgenic cultures. Postnatal midbrain neurons died by either necrosis or apoptosis, and increased Cu/Zn-SOD activity attenuated both forms of cell death. Furthermore, increased Cu/Zn-SOD activity better prevented the loss of dopaminergic neurons than GABAergic neurons. We also found that neuronal processes were dramatically denser in transgenic cultures than in nontransgenic cultures. These results indicate that chronic increased Cu/Zn-SOD activity does not appear to be detrimental, but rather promotes cell survival and neuronal process development in postnatal midbrain neurons, probably by providing more efficient detoxification of free radicals. They also show that increased Cu/Zn-SOD activity does not seem to play a critical role in determining the mode of cell death in this culture system.     

Effects of antioxidant therapy on leukocyte myeloperoxidase and Cu/Zn-superoxide dismutase and plasma malondialdehyde levels in experimental colitis

The aim of the present study was to evaluate the effects of N-acetylcysteine (NAC) and L-carnitine (LCAR) supplementations on polymorphonuclear leukocytes myeloperoxidase (MPO) and Cu/Zn-superoxide dismutase (Cu/Zn-SOD) and plasma malondialdehyde (MDA) in acetic acid (AA)-induced ulcerative colitis model. The mean polymorphonuclear leukocyte MPO and Cu/Zn-SOD activity was significantly higher in the colitis group than in the control group. Both NAC and LCAR pretreatment markedly decreased MPO and Cu/Zn-SOD activity compared to colitis group. AA administration significantly increased the levels of plasma MDA in comparison with controls. However, NAC and LCAR administration to the AA-treated rats significantly reduced the MDA levels compared to colitis group. In conclusion NAC and LCAR could be beneficial agents in restoring the circulating proinflammatory mediators.     

The protective effect of the vagus nerve in a murine model of chronic relapsing colitis

The vagus nerve inhibits the response to systemic administration of endotoxin, and we have recently extended this observation to show that the vagus attenuates acute experimental colitis in mice. The purpose of the present study was to determine whether there is a tonic counterinflammatory influence of the vagus on colitis maintained over several weeks. We assessed disease activity index, macroscopic and histological damage, myeloperoxidase (MPO) activity, and Th1 and Th2 cytokine profiles in chronic colitis induced by administration of dextran sodium sulfate (DSS) in drinking water for three cycles during 5 days with 11 days of rest between each cycle (DSS 3, 2, 2%) in healthy and vagotomized C57BL/6 mice and in mice deficient in macrophage-colony stimulating factor (M-CSF). A pyloroplasty was performed in vagotomized mice. Vagotomy accelerated the onset and the severity of inflammation during the first and second but not the third cycle. Although macroscopic scores were not significantly changed, histological scores as well as MPO activity and colonic tissue levels of IL-1alpha, TNF-alpha, IFN-gamma, and IL-18 but not IL-4 were significantly increased in vagotomized mice compared with sham-operated mice that received DSS. In control mice (without colitis), vagotomy per se did not affect any inflammatory marker. Vagotomy had no effect on the colitis in M-CSF-derived macrophage-deficient mice. These results indicate that the vagus protects against acute relapses on a background of chronic inflammation. Identification of the molecular mechanisms underlying the protective role of parasympathetic nerves opens a new therapeutic avenue for the treatment of acute relapses of chronic inflammatory bowel disease.     

Chemically induced mouse models of intestinal inflammation

Animal models of intestinal inflammation are indispensable for our understanding of the pathogenesis of Crohn disease and ulcerative colitis, the two major forms of inflammatory bowel disease in humans. Here, we provide protocols for establishing murine 2,4,6-trinitro benzene sulfonic acid (TNBS)-, oxazolone- and both acute and chronic dextran sodium sulfate (DSS) colitis, the most widely used chemically induced models of intestinal inflammation. In the former two models, colitis is induced by intrarectal administration of the covalently reactive reagents TNBS/oxazolone, which are believed to induce a T-cell-mediated response against hapten-modified autologous proteins/luminal antigens. In the DSS model, mice are subjected several days to drinking water supplemented with DSS, which seems to be directly toxic to colonic epithelial cells of the basal crypts. The procedures for the hapten models of colitis and acute DSS colitis can be accomplished in about 2 weeks but the protocol for chronic DSS colitis takes about 2 months.     

Amelioration of dextran sulfate sodium-induced colitis in mice by oral administration of beta-caryophyllene, a sesquiterpene

beta-Caryophyllene (BCP), a naturally occurring plant sesquiterpene, was examined for anti-inflammatory activity in a mouse model of experimental colitis induced by dextran sulfate sodium (DSS). Colitis was induced by exposing male BALB/c mice to 5% DSS in drinking water for 7 days. BCP in doses of 30 and 300 mg/kg was administered orally once a day, beginning concurrently with exposure to DSS. The body weight and colon length were measured, and histological damage and myeloperoxidase (MPO) activity as well as inflammatory cytokines were assessed in both serum and colonic tissue after 7 days of treatment with DSS. The DSS treatment damaged the colonic tissue, increased MPO activity and inflammatory cytokines, lowered the body weight, and shortened the length of the colon. Oral administration of BCP at 300 mg/kg significantly suppressed the shortening of colon length and slightly offset the loss of body weight. BCP treatment (300 mg/kg) also significantly reduced the inflammation of colon and reversed the increase in MPO activity that had been induced by exposure to DSS. Further, BCP significantly suppressed the serum level of IL-6 protein (a 55% reduction) as well as the level of IL-6 mRNA in the tissue. These results demonstrate that BCP ameliorates DSS-induced experimental colitis, and may be useful in the prevention and treatment of colitis.     

Protective effects of Lactobacillus rhamnosus [corrected] and Bifidobacterium infantis in murine models for colitis do not involve the vagus nerve

The vagus nerve is an important pathway signaling immune activation of the gastrointestinal tract to the brain. Probiotics are live organisms that may engage signaling pathways of the brain-gut axis to modulate inflammation. The protective effects of Lactobacillus rhamnosus [corrected] (LR) and Bifidobacterium infantis (BI) during intestinal inflammation were studied after subdiaphragmatic vagotomy in acute dextran sulfate sodium (DSS) colitis in BALB/c mice and chronic colitis induced by transfer of CD4(+) CD62L(+) T lymphocytes from BALB/c into SCID mice. LR and BI (1 x 10(9)) were given daily. Clinical score, myeloperoxidase (MPO) levels, and in vivo and in vitro secreted inflammatory cytokine levels were found to be more severe in mice that were vagotomized compared with sham-operated animals. LR in the acute DSS model was effective in decreasing the MPO and cytokine levels in the tissue in sham and vagotomized mice. BI had a strong downregulatory effect on secreted in vitro cytokine levels and had a greater anti-inflammatory effect in vagotomized- compared with sham-operated mice. Both LR and BI retained anti-inflammatory effects in vagotomized mice. In SCID mice, vagotomy did not enhance inflammation, but BI was more effective in vagotomized mice than shams. Taken together, the intact vagus has a protective role in acute DSS-induced colitis in mice but not in the chronic T cell transfer model of colitis. Furthermore, LR and BI do not seem to engage their protective effects via this cholinergic anti-inflammatory pathway, but the results interestingly show that, in the T cell, transfer model vagotomy had a biological effect, since it increased the effectiveness of the BI in downregulation of colonic inflammation.     

Role of M-CSF-dependent macrophages in colitis is driven by the nature of the inflammatory stimulus

Although macrophages are considered a critical factor in determining the severity of acute inflammatory responses in the gut, recent evidence has indicated that macrophages may also play a counterinflammatory role. In this study, we examined the role of a macrophage subset in two models of colitis. Macrophage colony-stimulating factor (M-CSF)-deficient osteopetrotic mice (op/op) and M-CSF-expressing heterozygote (+/?) mice were studied following the induction of colitis by either dinitrobenzene sulfonic acid (DNBS) or dextran sulfate sodium (DSS). DNBS induced a severe colitis in M-CSF-deficient op/op mice compared with +/? mice. This was associated with increased mortality and more severe macroscopic and microscopic injury. Colonic tissue myeloperoxidase (MPO) activity as well as concentrations of TNF-alpha, IL-1beta, and IL-6 were higher and IL-10 lower in op/op mice with DNBS colitis. The severity of inflammation and mortality was attenuated in op/op mice that had received human recombinant M-CSF prior to the induction of colitis. In contrast, op/op mice appeared less vulnerable to colitis induced by DSS. Macroscopic damage, microscopic injury, MPO activity, and tissue concentrations of TNF-alpha, IL-1beta, and IL-6 were all lower in op/op mice compared with +/? mice with DSS colitis, and no changes were seen in IL-10. Macrophage inflammatory protein-1alpha concentrations were increased in op/op but not +/? mice following colitis induced by DNBS but not DSS. These results indicate that M-CSF-dependent macrophages may play either a pro- or counterinflammatory role in acute experimental colitis, depending on the stimulus used to induce colitis.     

Investigating Intestinal Inflammation in DSS-induced Model of IBD

Inflammatory bowel disease (IBD) encompasses a range of intestinal pathologies, the most common of which are ulcerative colitis (UC) and Crohn''s Disease (CD). Both UC and CD, when present in the colon, generate a similar symptom profile which can include diarrhea, rectal bleeding, abdominal pain, and weight loss.¹ Although the pathogenesis of IBD remains unknown, it is described as a multifactorial disease that involves both genetic and environmental components.²There are numerous and variable animal models of colonic inflammation that resemble several features of IBD. Animal models of colitis range from those arising spontaneously in susceptible strains of certain species to those requiring administration of specific concentrations of colitis-inducing chemicals, such as dextran sulphate sodium (DSS). Chemical-induced models of gut inflammation are the most commonly used and best described models of IBD. Administration of DSS in drinking water produces acute or chronic colitis depending on the administration protocol.³ Animals given DSS exhibit weight loss and signs of loose stool or diarrhea, sometimes with evidence of rectal bleeding.^4,5 Here, we describe the methods by which colitis development and the resulting inflammatory response can be characterized following administration of DSS. These methods include histological analysis of hematoxylin/eosin stained colon sections, measurement of pro-inflammatory cytokines, and determination of myeloperoxidase (MPO) activity, which can be used as a surrogate marker of inflammation.⁶The extent of the inflammatory response in disease state can be assessed by the presence of clinical symptoms or by alteration in histology in mucosal tissue. Colonic histological damage is assessed by using a scoring system that considers loss of crypt architecture, inflammatory cell infiltration, muscle thickening, goblet cell depletion, and crypt abscess.⁷ Quantitatively, levels of pro-inflammatory cytokines with acute inflammatory properties, such as interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α,can be determined using conventional ELISA methods. In addition, MPO activity can be measured using a colorimetric assay and used as an index of inflammation.⁸In experimental colitis, disease severity is often correlated with an increase in MPO activity and higher levels of pro-inflammatory cytokines. Colitis severity and inflammation-associated damage can be assessed by examining stool consistency and bleeding, in addition to assessing the histopathological state of the intestine using hematoxylin/eosin stained colonic tissue sections. Colonic tissue fragments can be used to determine MPO activity and cytokine production. Taken together, these measures can be used to evaluate the intestinal inflammatory response in animal models of experimental colitis.     

Oral nitrite ameliorates dextran sulfate sodium-induced acute experimental colitis in mice

Inflammatory bowel diseases (IBDs) such as Crohn’s disease and ulcerative colitis are chronic inflammatory disorders of the intestinal tract with excessive production of cytokines, adhesion molecules, and reactive oxygen species. Although nitric oxide (NO) is reported to be involved in the onset and progression of IBDs, it remains controversial as to whether NO is toxic or protective in experimental colitis. We investigated the effects of oral nitrite as a NO donor on dextran sulfate sodium (DSS)-induced acute colitis in mice. Mice were fed DSS in their drinking water with or without nitrite for up to 7 days. The severity of colitis was assessed by disease activity index (DAI) observed over the experimental period, as well as by the other parameters, including colon lengths, hematocrit levels, and histological scores at day 7. DSS treatment induced severe colitis by day 7 with exacerbation in DAI and histological scores. We first observed a significant decrease in colonic nitrite levels and increase in colonic TNF-α expression at day 3 after DSS treatment, followed by increased colonic myeloperoxidase (MPO) activity and increased colonic expressions of both inducible NO synthase (iNOS) and heme oxygenase-1 (HO-1) at day 7. Oral nitrite supplementation to colitis mice reversed colonic nitrite levels and TNF-α expression to that of normal control mice at day 3, resulting in the reduction of MPO activity as well as iNOS and HO-1 expressions in colonic tissues with clinical and histological improvements at day 7. These results suggest that oral nitrite inhibits inflammatory process of DSS-induced experimental colitis by supplying nitrite-derived NO instead of impaired colonic NOS activity.     

Effects of monocolonization with<Emphasis Type="Italic">Escherichia coli</Emphasis> strains O6K13 and nissle 1917 on the development of experimentally induced acute and chronic intestinal inflammation in germ-free immunocompetent and immunodeficient mice

Germ-free immunocompetent (BALB/c) and immunodeficient (SCID) mice were colonized either by E. coli O6K13 or by E. coli strain Nissle 1917 and intestinal inflammation was induced by administering 2.5% dextran sulfate sodium (DSS) in drinking water. Controls were germ-free mice which demonstrated only mild inflammatory changes after induction of an acute intestinal inflammation with DSS as compared with conventional mice in which acute colitis of the colon mucosa similar to human ulcerative colitis is elicited. In mice monocolonized with the nonpathogenic E. coli Nissle 1917 the inflammatory disease did not develop (damage grade 0) while animals monocolonized with uropathogenic E. coli O6K13 exhibited inflammatory changes similar to those elicited in conventionally reared mice (damage grade 3). In the chronic inflammation model, immunocompetent BALB/c mice monocolonized with E. coli Nissle 1917 showed no conspicuous inflammatory changes of the colon mucosa whereas those monocolonized with E. coli O6K13 developed colon inflammation associated with marked infiltration of inflammatory cells. In contrast to germ-free immunodeficient SCID mice that died after application of DSS, the colon mucosa of SCID mice monoassociated with E. coli Nissle 1917 exhibited only moderate inflammatory changes which were less pronounced than changes of colon mucosa of SCID mice monoassociated with E. coli O6K13.     

Pathophysiological studies of trinitrobenzene sulfonic acid-induced colitis in Syrian hamsters (Mesocricetus auratus)

We developed a colitis model in Syrian hamsters (Mesocricetus auratus) to investigate the relationship between colitis and neutrophil elastase (NE). Colitis was induced by a single intracolonic dose of trinitrobenzene sulfonic acid (TNBS; 90 mg/ml) dissolved in 15% (vol/vol) ethanol. The ulcer area, tissue myeloperoxidase (MPO) activity, and luminal NE activity all were increased on Days 1 and 5, corresponding with the acute inflammatory histopathological changes. These acute inflammatory parameters subsequently decreased by Day 14, and chronic inflammatory histopathological changes became evident. Recurrence of inflammation was not observed during the period up to Day 28. To evaluate our colitis model, the effects of prednisolone were examined. Prednisolone was administered orally once on the day before induction of colitis, and animals were treated twice daily thereafter. Although prednisolone had little effect on the tissue MPO activity, prednisolone inhibited the ulcer area and NE activity. In addition, the effects of an NE-specific inhibitor (ONO-6818) on our TNBS-induced colitis model were examined. In the subcutaneous treatment study, ONO-6818 was administered once before the induction of colitis. Although ONO-6818 had little effect on the tissue MPO activity, the ulcer area and NE activity were decreased in the ONO-6818-treated group. The inhibitory effects on the ulcer area and NE activity were confirmed after oral treatment with ONO-6818 after induction of colitis. We conclude that our colitis model is useful for investigating the relationship between colitis and NE, and inhibition of NE activity can prevent the progression of ulceration.     

Effect of overexpression of human Cu/Zn-SOD on activation-induced lymphocyte proliferation and apoptosis

The process of lymphocyte proliferation and apoptosis is known to be linked to oxidative stress. In the present study, we have used a new transgenic mouse model to investigate the effect of human Cu/Zn superoxide dismutase (Cu/Zn-SOD) overexpression on activation-induced lymphocytes proliferation and apoptosis. Cu/Zn-SOD activity was 3.5-fold higher in the spleen of the transgenic mice overexpressing Cu/Zn-SOD (Tg-Cu/Zn-SOD) compared to the wild-type littermates. Proliferative response of lymphocytes to lipopolysaccharide (LPS), Concanavalin A (Con A), and anti-CD3 was measured by [3H]-thymidine incorporation. Activation-induced apoptosis was determined by incubating the T cells with anti-CD3 (primary stimulus) for 72 h, followed by restimulation with Con A (secondary stimulus) for various times. Apoptosis was assessed by measuring DNA fragmentation using a spectrofluorimetric assay and monitoring the expression of the specific apoptotic markers (Fas/CD95 receptor and Fas/CD95 ligand (Fas-L) using flow cytometry. There was no significant difference in proliferative response of lymphocytes to LPS, Con A, or anti-CD3 in transgenic mice overexpressing human Cu/Zn superoxide dismutase (Tg-Cu/Zn-SOD) compared to wild-type littermates. In addition, no significant difference was observed in lymphocyte populations and subsets between Tg-Cu/Zn-SOD mice and wild-type littermates. However, splenic T cells from Tg-Cu/Zn-SOD mice exhibited a significantly (p <.05) higher level of activation-induced DNA fragmentation than T cells from wild-type littermates. The increase in DNA fragmentation was paralleled with an increase in the proportion of T cells expressing Fas and Fas-L molecules. The possible consequences of Cu/Zn-SOD overproduction on activation-induced apoptosis are discussed.     

Detection of ICAM-1 in experimentally induced colitis of ICAM-1-deficient and wild-type mice: an immunohistochemical study

Adhesion molecules (e.g. ICAM-1, CD 54) are known to be upregulated on activated vascular endothelial cells during inflammatory reactions. To study the role of ICAM-1 in intestinal inflammation in vivo, we induced acute experimental colitis in wild-type (C57BL/6) mice and ICAM-1-deficient mice, by feeding the animals with 3% dextran sodium sulphate (DSS) in drinking water for 7 days. In the control strain the immunohistochemical staining showed a very pronounced endothelial upregulation of ICAM-1 after the DSS treatment observed in areas of inflammatory infiltrate, especially in venules or arterioles of the propria and submucosa, and partly in the mesocolon. DSS-fed ICAM-1-deficient mice showed no endothelial enhancement and only faint staining of venules or capillaries approaching that encountered in the control ICAM-1-deficient animals. Our data indicate that ICAM-1 may play a crucial role in the development of acute intestinal inflammation, consistent with our finding that ICAM-1 deficiency can obviate severe forms of experimentally induced colitis in mice.     

Somatostatin does not attenuate intestinal injury in dextran sodium sulphate-induced subacute colitis.

FRom several in vitro and in vivo studies involvement of somatostatin (SMS) in intestinal inflammation emerge. Acute colitis induced in rats is attenuated by the long-acting SMS analogue octreotide. We studied the potential beneficial effect of SMS on non-acute experimental colitis. BALB/c mice received either saline, SMS-14 (36 or 120 microg daily) or octreotide (3 microg daily) subcutaneously delivered by implant osmotic pumps. A non-acute colitis was induced by administration of dextran sodium sulphate (DSS) 10% in drinking water during 7 days. DSS evoked a mild, superficial pancolitis, most characterized by mucosal ulceration and submucosal influx of neutrophils. Neither SMS-14 nor octreotide reduced mucosal inflammatory score or macroscopical disease activity, although reduction of intestinal levels of interleukin-1beta (IL-1beta), IL-6 and IL-10 during DSS was augmented both by SMS and octreotide. A slight increase of neutrophil influx was seen during SMS administration in animals not exposed to DSS. In conclusion, SMS or its long-acting analogue did not reduce intestinal inflammation in non-acute DSS-induced colitis. According to the cytokine profile observed, SMS-14 and octreotide further diminished the reduction of intestinal macrophage and Th2 lymphocyte activity.     

Modulatory effects of estrogen in two murine models of experimental colitis

The association between oral contraceptives or pregnancy and inflammatory bowel disease is unclear. We investigated whether 17beta-estradiol modulates intestinal inflammation in two models of colitis. Female mice were treated with 17beta-estradiol alone or with tamoxifen, tamoxifen alone, 17 alpha-estradiol, or placebo. Dinitrobenzene sulfonic acid (DNB)- or dextran sodium sulfate (DSS)-induced colitis were assessed macroscopically, histologically, and by myeloperoxidase (MPO) activity. Malondialdehyde and mRNA levels of intercellular adhesion molecule-1 (ICAM-1), interferon-gamma (IFN-gamma), and interleukin-13 (IL-13) were determined. In DNB colitis, 17beta-estradiol alone, but not 17beta-estradiol plus tamoxifen, or 17 alpha-estradiol reduced macroscopic and histological scores, MPO activity and malondialdehyde levels. 17beta-Estradiol also decreased the expression of ICAM-1, IFN-gamma, and IL-13 mRNA levels compared with placebo. In contrast, 17beta-Estradiol increased the macroscopic and histological scores compared with placebo in mice with DSS colitis. These results demonstrate anti-inflammatory and proinflammatory effects of 17beta-estradiol in two different models of experimental colitis. The net modulatory effect most likely reflects a combination of estrogen receptor-mediated effects and antioxidant activity and may explain, in part, conflicting results from clinical trials.     

Preventative oral methylthioadenosine is anti-inflammatory and reduces DSS-induced colitis in mice

Methylthioadenosine (MTA) is a precursor of the methionine salvage pathway and has been shown to have anti-inflammatory properties in various models of acute and chronic inflammation. However, the anti-inflammatory properties of MTA in models of intestinal inflammation are not defined. We hypothesized that orally administered MTA would be bioavailable and reduce morbidity associated with experimental colitis. We examined clinical, histological, and molecular markers of disease in mice provided oral MTA before (preventative) or after (therapy) the induction of colitis with 3% dextran sulfate sodium (DSS). We found a reduction in disease activity, weight loss, myeloperoxidase activity, and histological damage in mice given preventative MTA compared with DSS alone. We also found that equivalent supplementation with methionine could not reproduce the anti-inflammatory effects of MTA, and that MTA had no detectable adverse effects in control or DSS mice. Expression microarray analysis of colonic tissue showed several dominant pathways related to inflammatory cytokines/chemokines and extracellular matrix remodeling were upregulation by DSS and suppressed in MTA-supplemented mice. MTA is rapidly absorbed in the gastrointestinal tract and disseminated throughout the body, based on a time course analysis of an oral bolus of MTA. This effect is transient, with MTA levels falling to near baseline within 90 min in most organs. Moreover, MTA did not lead to increased blood or tissue methionine levels, suggesting that its effects are specific. However, MTA provided limited therapeutic benefit when administered after the onset of colitis. Our results show that oral MTA supplementation is a safe and effective strategy to prevent inflammation and tissue injury associated with DSS colitis in mice. Additional studies in chronic inflammatory models are necessary to determine if MTA is a safe and beneficial option for the maintenance of remission in human inflammatory bowel disease.     

Myeloperoxidase deficiency attenuates systemic and dietary iron-induced adverse effects

Iron deficiency is routinely treated with oral or systemic iron supplements, which are highly reactive and could induce oxidative stress via augmenting the activity of proinflammatory enzyme myeloperoxidase (MPO). To investigate the extent to which MPO is involved in iron-induced toxicity, acute (24 h) iron toxicity was induced by intraperitoneal administration of FeSO₄ (25 mg/kg body weight) to MPO-deficient (MpoKO) mice and their wild-type (WT) littermates. Acute iron toxicity was also assessed in WT mice pretreated with an MPO inhibitor, 4-aminobenzoic acid hydrazide. Systemic iron administration up-regulated circulating MPO and neutrophil elastase and elevated systemic inflammatory and organ damage markers in WT mice. However, genetic deletion of MPO or its inhibition significantly reduced iron-induced organ damage and systemic inflammatory responses. In contrast to the acute model, 8 weeks of 2% carbonyl iron diet feeding to WT mice did not change the levels of circulating MPO and neutrophil elastase but promoted their accumulation in the liver. Even though both MpoKO and WT mice displayed similar levels of diet-induced hyperferremia, MpoKO mice showed significantly reduced inflammatory response and oxidative stress than the WT mice. In addition, WT bone-marrow-derived neutrophils (BMDN) generated more reactive oxygen species than MPO-deficient BMDN upon iron stimulation. Altogether, genetic deficiency or pharmacologic inhibition of MPO substantially attenuated acute and chronic iron-induced toxicity. Our results suggest that targeting MPO during iron supplementation is a promising approach to reduce iron-induced toxicity/side effects in vulnerable population.     

Xanthorrhizol attenuates dextran sulfate sodium-induced colitis via the modulation of the expression of inflammatory genes in mice

AimsThe aim of this study was to investigate the effects of xanthorrhizol (5-(1,5-dimethyl-4-hexenyl)-2-methylphenol, XA) in a mouse model of dextran sulfate sodium (DSS)-induced colitis.Main methodsExperimental colitis was induced by exposing male BALB/c mice to 5% DSS in drinking water for 7 days. XA (10 or 100 mg/kg) was administered orally once a day, together with the DSS. We evaluated body weight, colon length, histological changes, and myeloperoxidase (MPO) activity. A cDNA microarray was used to assess the gene expression profiles that were affected by XA and DSS treatment and a co-citation analysis was used to examine the biological relationship between XA-responsive genes and colitis.Key findingsDecreased body weight, shortened colon length, and damaged colon were observed in the group that was exposed to DSS. Oral administration of XA (10 or 100 mg/kg) rescued these symptomatic and histopathological features. The DSS-induced increase in MPO activity, which was used as an index of neutrophil infiltration, was significantly decreased after treatment with XA. Microarray analysis revealed that XA treatment regulated the expression of 34 genes that were altered by exposure to DSS, and that these XA-responsive genes were associated with colonic inflammation. Furthermore, co-citation analysis and graphing of XA-responsive genes revealed a network associated with the gene that encodes for MPO.SignificanceThese results suggest that XA attenuates acute DSS-induced colitis, possibly by modulating the expression of genes mostly associated with colonic inflammation.