IL-33 signalling in liver immune cells enhances drug-induced liver injury and inflammation.

OBJECTIVE AND DESIGN: The aim of this study was to investigate the contribution of IL-33/ST2 axis in the onset and progression of acute liver injury using a mice model of drug-induced liver injury (DILI). MATERIAL AND TREATMENTS: DILI was induced by overdose administration of acetaminophen (APAP) by oral gavage in wild-type BALB/c, ST2-deficient mice and in different bone marrow chimeras. Neutrophils were depleted by anti-Ly6G and macrophages with clodronate liposomes (CLL). METHODS: Blood and liver were collected for biochemical, immunologic and genetic analyses. Mice were imaged by confocal intravital microscopy and liver non-parenchymal cells and hepatocytes were isolated for flow cytometry, genetic and immunofluorescence studies. RESULTS: Acetaminophen overdose caused a massive necrosis and accumulation of immune cells within the liver, concomitantly with IL-33 and chemokine release. Liver non-parenchymal cells were the major sensors for IL-33, and amongst them, neutrophils were the major players in amplification of the inflammatory response triggered by IL-33/ST2 signalling pathway. CONCLUSION: Blockage of IL-33/ST2 axis reduces APAP-mediated organ injury by dampening liver chemokine release and activation of resident and infiltrating liver non-parenchymal cells.

Hydrolyzed whey protein prevents the development of food allergy to ß-lactoglobulin in sensitized mice.

Food allergy is an adverse immune response to dietary proteins. Hydrolysates are frequently used for children with milk allergy. However, hydrolysates effects afterwards are poorly studied. The aim of this study was to investigate the immunological consequences of hydrolyzed whey protein in allergic mice. For that, we developed a novel model of food allergy in BALB/c mice sensitized with alum-adsorbed ß-lactoglobulin. These mice were orally challenged with either whey protein or whey hydrolysate. Whey-challenged mice had elevated levels of specific IgE and lost weight. They also presented gut inflammation, enhanced levels of SIgA and IL-5 as well as decreased production of IL-4 and IL-10 in the intestinal mucosa. Conversely, mice challenged with hydrolyzate maintained normal levels of IgE, IL-4 and IL-5 and showed no sign of gut inflammation probably due to increased IL-12 production in the gut. Thus, consumption of hydrolysate prevented the development of clinical signs of food allergy in mice.

Bacteroides fragilis response to subinhibitory concentrations of antimicrobials includes different morphological, physiological and virulence patterns after in vitro selection.

As antimicrobials are introduced into the environment, microorganisms may respond in different ways, sometimes displaying alterations in cellular physiology. Considering the clinical relevance of the Bacteroides fragilis, strains were selected to investigate bacterial response after exposure to subinhibitory concentrations (SIC) of ampicillin (AMP), ampicillin-sulbactam (AMS), clindamycin (CLI), chloramphenicol (CHL), and its relationship to a host model (BALB/c mice) after experimental challenge. Morphological alterations, and biochemical-physiological and genetic profiles were evaluated among drug-selected bacteria. Histopathological evaluation of the liver and spleen, and inflammatory cytokines were determined after bacterial infection in mice. AMP and AMS exposure were related to most significant cellular alterations. Decreased sensitivity to all antimicrobials was observed for all drug-selected bacteria. Down regulation in adherence properties were also observed. Spleen and liver alterations were observed in different patterns. Increased levels of TNF-α, IL-6 and IFN-γ were also observed. Our results show that SICs of AMP, AMS, CLI and CHL may be related to alterations in cell physiology in B. fragilis with implications to the host-bacteria relationship. The data emphasizes the risks of inappropriate chemotherapy, and the concerns regarding ecological consequences lead by SICs of antimicrobials in resident microbiota.

Interleukin-4 deficiency protects mice from acetaminophen-induced liver injury and inflammation by prevention of glutathione depletion.

OBJECTIVE: Interleukin-4 (IL-4) is a multifunctional cytokine involved in many diseases such as autoimmune hepatitis and idiosyncratic drug reactions. However, its role in acetaminophen (APAP)-induced liver injury remains unclear. Our objective was to evaluate the contribution of IL-4 to the pathogenesis of APAP-induced liver injury. METHODS: Balb/C (WT) and IL-4 knockout (IL-4(-/-)) mice were orally overdosed with APAP. After 24 h, survival percentage, biochemical and morphological markers of liver injury, and tissue inflammation were assessed. RESULTS: IL-4(-/-) mice were protected from APAP toxicity. Intravital confocal microscopy, tissue histology and serum ALT levels showed significantly less liver injury and inflammation than in the WT group, which may explain the increased survival rate of IL-4(-/-) mice. In addition, IL-4(-/-) mice had decreased production of tumor necrosis factor α, CXCL1 and interleukin-1ß in the liver, but not in a remote site such as the lungs. Hepatic macrophage activation was markedly reduced in IL-4-deficient mice. In addition, glutathione depletion-a primary cause of APAP-mediated injury-was significantly attenuated in IL-4(-/-) mice. CONCLUSIONS: Taken together, our data demonstrate that IL-4(-/-) mice are protected from APAP-induced liver injury due to reduced depletion of glutathione, which prevented liver damage and tissue inflammation.

Prolonged ingestion of ovalbumin diet by Ova sensitized mice suppresses mBSA-induced arthritis.

Concomitant chronic diseases are a common finding in clinics and may consist in a major issue in therapeutics. Here, we investigated whether prolonged ingestion of ovalbumin (Ova) by sensitized mice would reduce the severity of an associated concurrent immunomediated condition such as antigen-induced arthritis (AIA). AIA was induced by administration of methylated bovine albumin (mBSA) into the knee joints of previously immunized mice, and evaluated by articular leukocyte trafficking and levels of cytokines (TNF-α, IL-1ß) and chemokine (CXCL-1) in the periarticular tissue. Continuous Ova feeding by Ova sensitized mice decreased serum levels of anti-Ova IgE, and led to a significant suppression of leukocyte adhesion and infiltration into synovial tissue and cavity. Also, a marked cytokine reduction was observed, suggesting that prolonged ingestion of ovalbumin by sensitized mice suppresses specific IgE production with concomitant reduction in peripheral T cells, which may impact in the pathogenesis of AIA, a non-related condition.

Immunomodulatory effects of different strains of Lactococcus lactis in DSS-induced colitis.

Inflammatory bowel diseases (IBD) are gastrointestinal disorders characterized by a breakdown in intestinal homeostasis by inflammatory immune responses to luminal antigens. Novel strategies for ameliorating IBD have been proposed in many studies using animal models. Our group has demonstrated that administration of Lactococcus lactis NCDO 2118 can improve clinical parameters of colitis induced by oral administration of dextran sulphate sodium (DSS). However, it is not clear whether other strains of L. lactis can yield the same effect. The objective of present study was to analyze the effects of three different L. lactis strains (NCDO2118, IL1403 and MG1363) in the development of DSS-induced colitis in C57BL/6 mice. Acute colitis was induced in C57/BL6 mice by the administration of 2% DSS during 7 consecutive days. Body weight loss and shortening of colon length were observed in DSS-treated mice, and none of L. lactis strains had an impact in these clinical signs of colitis. On the other hand, all strains improved the global macroscopical disease index and prevented goblet cells depletion as well as the increase of intestinal permeability. TNF-α production was reduced in gut mucosa of L. lactis DSS-treated mice indicating a modulation of a critical pro-inflammatory response by all strains tested. However, only L. lactis NCDO2118 and MG1363 induced a higher frequency of CD11c+CD11b-CD103+ tolerogenic dendritic cells in lymphoid organs of mice at steady state. We conclude that all tested strains of L. lactis improved the clinical scores and parameters of colitis, which confirm their anti-inflammatory properties in this model of colitis.

New insights into the immunological changes in IL-10-deficient mice during the course of spontaneous inflammation in the gut mucosa.

IL-10 is a regulatory cytokine that plays a major role in the homeostasis of the gut and this is illustrated by the fact that IL-10(-/-) mice develop spontaneous colitis. In this study, IL-10(-/-) mice were analyzed for immunological changes during colitis development. We found a reduced frequency of regulatory T cells CD4(+)CD25(+)Foxp3(+) and higher frequency of activated T cells in the colon that precedes the macroscopic signs of the disease. Production of IL-17 and IFN-γ was higher in the colon. Colitis progression culminates with the reduction of CD4(+)LAP(+) regulatory T cells in the intestine. Frequency of B1 cells and the secretory IgA production were both elevated. Despite these alterations, 16-week-old IL-10(-/-) mice could be rendered tolerant by a continuous feeding protocol. Our study provides detailed analysis of changes that precede colitis and it also suggests that oral tolerance could be used to design novel alternative therapies for the disease.

Dietary supplementation with omega-3-PUFA-rich fish oil reduces signs of food allergy in ovalbumin-sensitized mice.

We investigated the effect of dietary supplementation with n-3 PUFA (fish oil source) in an experimental model of food allergy. Mice were sensitized (allergic group) or not (nonallergic group) with OVA and were fed with OVA diet to induce allergy signals. Mice were fed with regular diet in which 7% of lipid content was provided by soybean (5% of n-3 PUFA) or fish (25% of n-3 PUFA) oil. Allergic group mice had increased serum levels of antiovalbumin IgE and IgG1 and changes in small intestine, characterized by an increased edema, number of rolling leukocytes in microcirculation, eosinophil infiltration, mucus production, and Paneth cell degranulation, in comparison to non-allergic group. All these inflammatory parameters were reduced in mice fed high-n-3-PUFA diet. Our data together suggest that diet supplementation with n-3 PUFA from fish oil may consist of a valid adjuvant in food allergy treatment.

Neuroimmune circuits involved in ß-lactoglobulin-induced food allergy.

Several antigens can act as allergens eliciting IgE-mediated food allergy reactions when fed to sensitized animals. One of them is ovalbumin (OVA) which is the main allergen in egg white. Allergic mice develop aversion to OVA consumption. This aversive behavior is associated with anxiety, and it can be transferred to non-sensitized mice by injection of serum of allergic mice. However, it is yet to be determined whether altered behavior is a general component of food allergy or whether it is specific for some types of allergens. Cow's milk allergy is the most prevalent food allergy that usually begins early in life and ß-lactoglobulin (BLG) is the milk component with the highest allergenicity. In this study, we investigated behavioral and neuroimmune circuits triggered by allergic sensitization to BLG. A neuroimmune conflict between aversion and reward was observed in a model of food allergy induced by BLG intake. Mice sensitized to BLG did not present aversive behavior when BLG was used for sensitization and oral challenge. Mice allergic to BLG preferred to drink the allergen-containing solution over water even though they had high levels of specific IgE, inflammatory cells in the intestinal mucosa and significant weight loss. When sensitized to OVA and challenged with the same antigen, mice had increased levels of neuron activation in the amygdala, a brain area related to anxiety. On the other hand, when mice were sensitized to OVA and received a mixture of BLG and OVA in the oral challenge, mice preferred to drink this mixture, despite their aversion to OVA, which was associated with neuron activation in the nucleus accumbens, an area related to reward behavior. Thus, the aversive behavior observed in food allergy to OVA does not apply to all antigens and some allergens may activate the brain reward system rather than anxiety and aversion. Our study provides novel insights into the neuroimmune conflicts regarding preference and avoidance to a common antigen associated with food allergy.

Experimental food allergy leads to adipose tissue inflammation, systemic metabolic alterations and weight loss in mice.

To investigate the consequences of food allergy in adipose tissue and metabolism, we used a murine model in which mice have been sensitized subcutaneously with ovalbumin and further received antigen-containing diet. Allergic mice presented a significant weight loss 7 days after oral challenge with a concomitant decrease in epididymal adipose tissue mass. This decrease was associated with increased lipolysis and local inflammation. In adipose tissue of allergic mice there were increased leukocyte rolling and adhesion in the microvasculature, increased number of leukocytes in the tissue, especially macrophages (F4/80(+) cells) and increased pro-inflammatory cytokines levels, including TNF-α, IL-6 and CCL2. In addition, we observed low serum concentrations of triglyceride, glucose, total cholesterol and free fatty acids in the allergic mice. Our results suggest that the induction of food allergy in mice leads to adipose tissue inflammation and systemic metabolic alterations that contribute to the weight loss observed.

Selective down-regulation of neutrophil Mac-1 in endotoxemic hepatic microcirculation via IL-10.

Hepatic neutrophil adhesion during endotoxemia is an integrin-independent, CD44-dependent process. Because integrins function in other endotoxemic vasculatures, we used spinning disk confocal intravital microscopy to assess whether LPS down-modulated integrin functions in sinusoids. First, we applied fMLP onto the liver surface, and compared it with systemic LPS administration. Local fMLP caused neutrophil adhesion, crawling, and emigration for at least 2 h. Surprisingly, the number of adherent and crawling neutrophils was markedly reduced in Mac-1(-/-) and ICAM-1(-/-) mice, but not in mice treated with anti-CD44 mAb. By contrast, systemic LPS injection induced a robust accumulation of neutrophils in sinusoids, which was dependent on CD44, but not on integrins. Strikingly, local fMLP could not induce any integrin-dependent adhesion in endotoxemic mice treated with anti-CD44 mAb, indicating that Mac-1-dependent neutrophil adhesion was inhibited by LPS. This response was localized to the hepatic microvasculature because neutrophils still adhered via integrins in brain microvasculature. ICAM-1/ICAM-2 levels were not decreased, but following LPS treatment, Mac-1 was down-regulated in neutrophils localized to liver, but not in the circulation. Mac-1 down-regulation in neutrophils was not observed in IL-10(-/-) mice. In vitro neutrophil incubation with IL-10 induced direct decrease of Mac-1 expression and adhesivity in LPS-stimulated neutrophils. Therefore, our data suggest that Mac-1 is necessary for neutrophil adhesion and crawling during local inflammatory stimuli in sinusoids, but during systemic inflammation, neutrophils are exposed to high concentrations of IL-10, leading to a CD44-dependent, integrin-independent adhesion. This may be a mechanism to keep neutrophils in sinusoids for intravascular trapping.

Brazilian green propolis inhibits inflammatory angiogenesis in a murine sponge model.

Angiogenesis and inflammation are persistent features of several pathological conditions. Propolis, a sticky material that honeybees collect from living plants, has been reported to have multiple biological effects including anti-inflammatory and anti-neoplasic activities. Here, we investigated the effects of water extract of green propolis (WEP) on angiogenesis, inflammatory cell accumulation and endogenous production of cytokines in sponge implants of mice over a 14-day period. Blood vessel formation as assessed by hemoglobin content and by morphometric analysis of the implants was reduced by WEP (500 mg kg(-1) orally) compared to the untreated group. The levels of vascular endothelial growth factor (VEGF) increased progressively in the treated group but decreased after Day 10 in the control group. Accumulation of neutrophils and macrophages was determined by measuring myeloperoxidase (MPO) and N-acetyl-ß-(D)-glucosaminidase (NAG) activities, respectively. Neutrophil accumulation was unaffected by propolis, but NAG activity was reduced by the treatment at Day 14. The levels TGF-ß1 intra-implant increased progressively in both groups but were higher (40%) at Day 14 in the control implants. The pro-inflammatory levels of TNF-α peaked at Day 7 in the control implants, and at Day 14 in the propolis-treated group. Our results indicate that the anti-inflammatory/anti-angiogenic effects of propolis are associated with cytokine modulation.

Aqueous extract of brazilian green propolis: primary components, evaluation of inflammation and wound healing by using subcutaneous implanted sponges.

Propolis is a chemically complex resinous bee product which has gained worldwide popularity as a means to improve health condition and prevent diseases. The main constituents of an aqueous extract of a sample of green propolis from Southeast Brazil were shown by high performance liquid chromatography/mass spectroscopy/mass spectroscopy to be mono- and di-O-caffeoylquinic acids; phenylpropanoids known as important constituents of alcohol extracts of green propolis, such as artepillin C and drupanin were also detected in low amounts in the aqueous extract. The anti-inflammatory activity of this extract was evaluated by determination of wound healing parameters. Female Swiss mice were implanted subcutaneously with polyesther-polyurethane sponge discs to induce wound healing responses, and administered orally with green propolis (500 mg kg(-1)). At 4, 7 and 14 days post-implantation, the fibrovascular stroma and deposition of extracellular matrix were evaluated by histopathologic and morphometric analyses. In the propolis-treated group at Days 4 and 7 the inflammatory process in the sponge was reduced in comparison with control. A progressive increase in cell influx and collagen deposition was observed in control and propolis-treated groups during the whole period. However, these effects were attenuated in the propolis-treated group at Days 4 and 7, indicating that key factors of the wound healing process are modulated by propolis constituents.

Role of IL-4 in aversion induced by food allergy in mice.

To ascertain the role of IL-4 in aversion to antigen induced by food allergy, wild type and IL-4 deficient BALB/c mice were sensitized with ovalbumin and challenged orally with egg white. Sensitized wild type mice had increased production of IL-4 by spleen and mesenteric lymph node cells in vitro, higher levels of serum anti-ovalbumin IgE and IgG1, aversion to ingestion of the antigen and loss of body weight after continuous oral challenge. Intestinal changes in wild type sensitized mice included eosinophil infiltration and increased mucus production. The IL-4 deficiency impaired the development of food allergy and the aversion to antigen, suggesting the involvement of the antigen specific antibodies. When IL-4 deficient mice received serum from sensitized wild type donors, the aversion was restored. These results indicate that production of IL-4 and specific IgE/IgG1 antibodies correlate with aversion to antigen induced by food allergy in mice.

Hsp65-Producing Lactococcocus lactis Prevents Antigen-Induced Arthritis in Mice.

Oral tolerance is the physiological process that enables the immune system to differentiate between harmless dietary and microbiota antigens from pathogen derived antigens. It develops at the mucosal surfaces and can result in local and systemic regulatory and anti-inflammatory effects. Translation of these benefits to the clinical practice faces limitations involving specificity and doses of antigen as well as regimens of feeding. To circumvent these problems, we developed a recombinant Hsp65 delivered by the acid lactic bacteria Lactococcus lactis NCDO 2118 directy in the intestinal mucosa. Hsp65 is a ubiquitous protein overexpressed in inflamed tissues and capable of inducing immunoregulatory mechanisms. L. lactis has probiotic properties and is commonly and safely used in dairy products. In this study, we showed that continuous delivery of HSP65 in the gut mucosa by L. lactis is a potent tolerogenic stimulus inducing regulatory CD4+LAP+ T cells that prevented collagen-induced and methylated bovine serum albumin-induced arthritis in mice. Clinical and histological signs of arthritis were inhibited as well as levels of inflammatory cytokines such as IL-17 and IFN-γ, serum titers of anti-collagen antibodies and rheumatoid factor. Oral administration of L. lactis induced alterations in microbiota composition toward an increased abundance of anaerobic bacteria such as Bifidobacterium and Lactobacillus. Tolerance to HSP65 and arthritis prevention induced by the recombinant L. lactis was associated with increase in IL-10 production by B cells and it was dependent on LAP+ T cells, IL-10 and TLR2 signaling. Therefore, HSP65-producing treatment induced effective tolerance and prevented arthritis development suggesting it can be used as a therapeutic tool for autoimmune diseases.

Beneficial Propionibacteria within a Probiotic Emmental Cheese: Impact on Dextran Sodium Sulphate-Induced Colitis in Mice.

BACKGROUNDS AND AIMS: Inflammatory Bowel Diseases (IBD), including Ulcerative Colitis (UC), coincide with alterations in the gut microbiota. Consumption of immunomodulatory strains of probiotic bacteria may induce or prolong remission in UC patients. Fermented foods, including cheeses, constitute major vectors for bacteria consumption. New evidences revealed anti-inflammatory effects in selected strains of Propionibacterium freudenreichii. We thus hypothesized that consumption of a functional cheese, fermented by such a strain, may exert a positive effect on IBD. METHODS: We investigated the impact of cheese fermented by P. freudenreichii on gut inflammation. We developed an experimental single-strain cheese solely fermented by a selected immunomodulatory strain of P. freudenreichii, CIRM-BIA 129. We moreover produced, in industrial conditions, an Emmental cheese using the same strain, in combination with Lactobacillus delbrueckii CNRZ327 and Streptococcus thermophilus LMD-9, as starters. Consumption of both cheeses was investigated with respect to prevention of Dextran Sodium Sulphate (DSS)-induced colitis in mice. RESULTS: Consumption of the single-strain experimental cheese, or of the industrial Emmental, both fermented by P. freudenreichii CIRM-BIA 129, reduced severity of subsequent DSS-induced colitis, weight loss, disease activity index and histological score. Both treatments, in a preventive way, reduced small bowel Immunoglobulin A (IgA) secretion, restored occludin gene expression and prevented induction of Tumor Necrosis Factor α (TNFα), Interferon γ (IFNγ) and Interleukin-17 (IL-17). CONCLUSIONS: A combination of immunomodulatory strains of starter bacteria can be used to manufacture an anti-inflammatory cheese, as revealed in an animal model of colitis. This opens new perspectives for personalised nutrition in the context of IBD.

Frontline Science: Abnormalities in the gut mucosa of non-obese diabetic mice precede the onset of type 1 diabetes.

Alterations in the composition of the intestinal microbiota have been associated with development of type 1 diabetes (T1D), but little is known about changes in intestinal homeostasis that contribute to disease pathogenesis. Here, we analyzed oral tolerance induction, components of the intestinal barrier, fecal microbiota, and immune cell phenotypes in non-obese diabetic (NOD) mice during disease progression compared to non-obese diabetes resistant (NOR) mice. NOD mice failed to develop oral tolerance and had defective protective/regulatory mechanisms in the intestinal mucosa, including decreased numbers of goblet cells, diminished mucus production, and lower levels of total and bacteria-bound secretory IgA, as well as an altered IEL profile. These disturbances correlated with bacteria translocation to the pancreatic lymph node possibly contributing to T1D onset. The composition of the fecal microbiota was altered in pre-diabetic NOD mice, and cross-fostering of NOD mice by NOR mothers corrected their defect in mucus production, indicating a role for NOD microbiota in gut barrier dysfunction. NOD mice had a reduction of CD103+ dendritic cells (DCs) in the MLNs, together with an increase of effector Th17 cells and ILC3, as well as a decrease of Th2 cells, ILC2, and Treg cells in the small intestine. Importantly, most of these gut alterations precede the onset of insulitis. Disorders in the intestinal mucosa of NOD mice can potentially interfere with the development of T1D due the close relationship between the gut and the pancreas. Understanding these early alterations is important for the design of novel therapeutic strategies for T1D prevention.

Oral supplementation with capsaicin reduces oxidative stress and IL-33 on a food allergy murine model.

BACKGROUND: Food allergy is an abnormal immune response to antigens introduced into the body through food. Its prevalence has increased in developed and developing countries. Natural products are traditionally used to alleviate and treat diseases, and diet can play a role in both the prevention and management of food allergy. The effects of capsaicin as an anti-oxidant, anticarcinogenic, and anti-inflammatory in the energy expenditure and suppression of fat accumulation have been demonstrated. This study evaluated the effect of oral supplementation with capsaicin on a food allergy model. METHODS: OVA-sensitized mice received ovalbumin solution, and they were fed with chow supplemented with capsaicin for 7 days. The control group received AIN-93 chow with no supplementation. IgE anti-ova, inflammatory infiltration, oxidative stress and metabolic analysis were performed. RESULTS: The results showed that capsaicin supplementation is not able to reduce characteristic signs of food allergy, such as production of IgE and weight loss. However, macrophages infiltration and IL-33 in proximal jejunum was reduced in OVA capsaicin group. In addition, hepatic triglycerides and intestinal hydroperoxides were reduced in both capsaicin groups. CONCLUSION: Oral supplementation with capsaicin attenuated important factors associated to food allergy such as inflammation and oxidative stress, suggesting better prognosis and evolution of the disease.

Differential involvement of cyclooxygenase isoforms in neutrophil migration in vivo and in vitro.

Pretreatment using celecoxib, a cyclooxygenase (COX) 2 inhibitor, or indomethacin, a nonselective COX inhibitor, reduced lypopolyssaccharide (LPS)-induced leukocyte migration to the rat peritoneal cavity. The effect of celecoxib (12 mg/kg) or indomethacin (2 mg/kg) on neutrophil chemotaxis induced by formyl-methionyl-leucyl-phenylalanine (FMLP) in an in vitro chemotactic assay (Boyden chamber) was investigated. Celecoxib and indomethacin inhibited chemotaxis induced by FMLP (Control=26.6+/-1.45, Celecoxib=12.8+/-3.04, Indomethacin=6.26+/-2.19 cells/field). When observed under intravital microscopy, a mouse cremaster preparation was used to assess the microvasculature to further investigate which step of cell recruitment was affected by these drugs. Celecoxib and indomethacin inhibited leukocyte migration induced by 0.05 microg/kg LPS injected into the cremaster muscle. However, the effect of celecoxib was associated with reduced cell rolling and adhesion, whereas indomethacin was only effective at inhibiting cell adhesion. Furthermore, SC560 pretreatment (a COX-1 selective inhibitor) of normal or LPS-challenged tissues did not alter leukocyte migration or cell adhesion, but it did enhance leukocyte rolling activity in both cases. Taken together, these results indicate that: 1) COX-1 activity is mainly related to leukocyte traffic under physiological conditions, and 2) COX-2 activity is mainly related to cell traffic under inflammatory conditions in vascular beds, suggesting a possible effect of selective COX-2 inhibitors on the expression of adhesion molecules.

Consumption of conjugated linoleic acid (CLA)-supplemented diet during colitis development ameliorates gut inflammation without causing steatosis in mice.

Dietary supplementation with conjugated linoleic acid (CLA) has been proposed for weight management and to prevent gut inflammation. However, some animal studies suggest that supplementation with CLA leads to the development of nonalcoholic fatty liver disease. The aims of this study were to test the efficiency of CLA in preventing dextran sulfate sodium (DSS)-induced colitis, to analyze the effects of CLA in the liver function, and to access putative liver alterations upon CLA supplementation during colitis. So, C57BL/6 mice were supplemented for 3 weeks with either control diet (AIN-G) or 1% CLA-supplemented diet. CLA content in the diet and in the liver of mice fed CLA containing diet were accessed by gas chromatography. On the first day of the third week of dietary treatment, mice received ad libitum a 1.5%-2.5% DSS solution for 7 days. Disease activity index score was evaluated; colon and liver samples were stained by hematoxylin and eosin for histopathology analysis and lamina propria cells were extracted to access the profile of innate cell infiltrate. Metabolic alterations before and after colitis induction were accessed by an open calorimetric circuit. Serum glucose, cholesterol, triglycerides and alanine aminotransaminase were measured; the content of fat in liver and feces was also accessed. CLA prevented weight loss, histopathologic and macroscopic signs of colitis, and inflammatory infiltration. Mice fed CLA-supplemented without colitis induction diet developed steatosis, which was prevented in mice with colitis probably due to the higher lipid consumption as energy during gut inflammation. This result suggests that CLA is safe for use during gut inflammation but not at steady-state conditions.