Pierre Déchelotte

L-alanyl-L-glutamine dipeptide-supplemented total parenteral nutrition reduces infectious complications and glucose intolerance in critically ill patients: The French controlled, randomized, double-blind, multicenter study*

Objective:Glutamine (Gln)–supplemented total parenteral nutrition (TPN) improves clinical outcome after planned surgery, but the benefits of Gln-TPN for critically ill (intensive care unit; ICU) patients are still debated. Design:Prospective, double-blind, controlled, randomized trial. Setting:ICUs in 16 hospitals in France. Patients:One-hundred fourteen ICU patients admitted for multiple trauma (38), complicated surgery (65), or pancreatitis (11). Interventions:Patients were randomized to receive isocaloric isonitrogenous TPN via a central venous catheter providing 37.5 kcal and 1.5 g amino acids·kg−1·day−1 supplemented with either L-alanyl-L-glutamine dipeptide (0.5 g·kg−1·day−1; Ala-Gln group, n = 58) or L-alanine + L-proline (control group, n = 56) over at least 5 days. Measurements and Main Results:Complicated clinical outcome was defined a priori by the occurrence of infectious complications (according to the criteria of the Centers for Disease Control and Prevention), wound complication, or death. The two groups were compared by chi-square test on an intention-to-treat basis. The two groups did not differ at inclusion for type and severity of injury (mean simplified acute physiology score II, 30 vs. 30.5; mean injury severity score, 44.9 vs. 42.3). Similar volumes of TPN were administered in both groups. Ala-Gln-supplemented TPN was associated with a lower incidence of complicated outcome (41% vs. 61%; p < .05), which was mainly due to a reduced infection rate per patient (mean, 0.45 vs. 0.71; p < .05) and incidence of pneumonia (10 vs. 19; p < .05). Early death rate during treatment and 6-month survival were not different. Hyperglycemia was less frequent (20 vs. 30 patients; p < .05) and there were fewer insulin-requiring patients (14 vs. 22; p < .05) in the Ala-Gln group. Conclusions:TPN supplemented with Ala-Gln dipeptide in ICU patients is associated with a reduced rate of infectious complications and better metabolic tolerance.

The Expression and the Cellular Distribution of the Tight Junction Proteins Are Altered in Irritable Bowel Syndrome Patients With Differences According to the Disease Subtype

OBJECTIVES:Recent studies have suggested that an increased intestinal permeability is involved in the pathophysilogy of irritable bowel syndrome (IBS). However, the differential expression of tight junctions (TJs) proteins according to IBS subtypes and symptoms remained unknown. The objective of this study was to study zonula occludens-1 (ZO-1), occludin, and claudin-1 in the colonic mucosa of patients with IBS.METHODS:Fifty IBS patients fulfilling the Rome III criteria and 31 controls were included. All types of IBS patients participated with predominant diarrhea (IBS-D, n=19), predominant constipation (IBS-C, n=14), constipation alternating with diarrhea (IBS-A, n=15), or unclassified (IBS-U, n=2). IBS symptom intensity was quantified on 10-cm Visual Analog Scale (VAS). TJ proteins (claudin-1, ZO-1, occludin) were quantified by quantitative reverse transcriptase–polymerase chain reaction (qRT–PCR), western blot, while their localization was determined by immunofluorescence.RESULTS:ZO-1 and occludin expression was lower in IBS patients compared with controls, whereas only a trend for a decrease of claudin-1 was observed. The mRNA levels remained unaffected. In the subgroup analyses, occludin and claudin-1 expression was decreased in IBS-D patients but not in IBS-C and IBS-A patients. The subcellular distribution of these three proteins was altered in IBS-C and IBS-D patients. Occludin (r=0.40, P<0.01) and claudin-1 (r=0.46, P<0.01) expression was correlated with the duration of symptoms. The expression of occludin was lower in patients with an abdominal pain intensity higher than 6 on the VAS (P<0.05).CONCLUSIONS:Occludin and claudin-1 appeared markedly affected in IBS-D patients. In addition, our results suggest that alteration of TJ proteins may be involved in the initiation of IBS and contribute to visceral hypersensitivity.

Bacterial genotoxin colibactin promotes colon tumour growth by inducing a senescence-associated secretory phenotype.

Background Escherichia coli strains harbouring the pks island (pks+ E. coli) are often seen in human colorectal tumours and have a carcinogenic effect independent of inflammation in an AOM/IL-10−/− (azoxymethane/interleukin) mouse model. Objective To investigate the mechanism sustaining pks+ E. coli-induced carcinogenesis. Method Underlying cell processes were investigated in vitro and in vivo (xenograft model) using intestinal epithelial cells infected by pks+ E. coli or by an isogenic mutant defective for pks (pks− E. coli). The results were supported by data obtained from an AOM/DSS (azoxymethane/dextran sodium sulphate) colon cancer mouse model and from human colon cancer biopsy specimens colonised by pks+ E. coli or pks− E. coli. Results Colibactin-producing E. coli enhanced tumour growth in both xenograft and AOM/DSS models. Growth was sustained by cellular senescence (a direct consequence of small ubiquitin-like modifier (SUMO)-conjugated p53 accumulation), which was accompanied by the production of hepatocyte growth factor (HGF). The underlying mechanisms involve microRNA-20a-5p, which targets SENP1, a key protein regulating p53 deSUMOylation. These results are consistent with the expression of SENP1, microRNA-20a-5p, HGF and phosphorylation of HGF receptor found in human and mouse colon cancers colonised by pks+ E. coli. Conclusion These data reveal a new paradigm for carcinogenesis, in which colibactin-induced senescence has an important role.

Autoantibodies against appetite-regulating peptide hormones and neuropeptides: Putative modulation by gut microflora

Abstract Objective Peptide hormones synthesized in gastrointestinal and adipose tissues in addition to neuropeptides regulate appetite and body weight. Previously, autoantibodies directed against melanocortin peptides were found in patients with eating disorders; however, it remains unknown whether autoantibodies directed against other appetite-regulating peptides are present in human sera and whether their levels are influenced by gut-related antigens. Methods Healthy women were studied for the presence of immunoglobulin (Ig) G and IgA autoantibodies directed against 14 key appetite-regulating peptides. The concept of molecular mimicry was applied to search in silico whether bacteria, viruses, or fungi contain proteins with amino acid sequences identical to appetite-regulating peptides. In addition, autoantibodies serum levels were studied in germ-free and specific pathogen-free rats. Results We found these IgG and IgA autoantibodies directed against leptin, ghrelin, peptide YY, neuropeptide Y, and other appetite-regulating peptides are present in human sera at levels of 100–900 ng/mL. Numerous cases of sequence homology with these peptides were identified among commensal and pathogenic micro-organisms including Lactobacilli, bacteroides, Helicobacter pylori, Escherichia coli, and Candida species. Decreased levels of IgA autoantibodies directed against several appetite-regulating peptides and increased levels of antighrelin IgG were found in germ-free rats compared with specific pathogen-free rats. Conclusion Healthy humans and rats display autoantibodies directed against appetite-regulating peptide hormones and neuropeptides, suggesting that these autoantibodies may have physiologic implications in hunger and satiety pathways. Gut-related antigens including the intestinal microflora may influence production of theses autoantibodies, suggesting a new link between the gut and appetite control.

Modulating effect of glutamine on IL-1β-induced cytokine production by human gut

BACKGROUND & AIMS Balance between pro-and anti-inflammatory mediators plays a key role in the pathogenesis and treatment of inflammatory bowel disease. Glutamine can modulate cytokine production by intestinal mucosa in healthy subjects, but studies in inflammatory states are still limited. The aim of this work was to evaluate the effects of glutamine on IL-1beta-induced cytokine production by human gut. METHODS Duodenal biopsies from healthy volunteers were stimulated in vitro by IL-1beta in the presence of increasing glutamine concentrations. Cytokine production was assessed in culture media by ELISA and cytokine mRNA expression in biopsies by RT-PCR. Results, in pg/mg of tissue, (median [range]), were compared by non-parametric paired tests. RESULTS IL-1beta stimulation increased IL-6 and IL-8, but did not affect IL-4 and IL-10 production. IL-8 and IL-6 production from stimulated biopsies significantly decreased with increasing glutamine concentration from 0.5 to 10mM, (2543 [828-3634] to 1499 [282-2617] for IL-8, 62 [22-117] to 24 [12-99] for IL-6, both P<0.05), whereas IL-10 production was increased (0.7 [0.2-1.6] to 1.2 [2.6-0.5],P<0.05). Glutamine also increased IL-10 mRNA level in biopsies (P<0.05). IL-4 production was not affected by glutamine. CONCLUSIONS Glutamine was shown in human intestinal mucosa to reduce the production of the pro-inflammatory cytokines IL-6 and IL-8, and enhance the production of the anti-inflammatory cytokine, IL-10.

An α-Linolenic Acid-Rich Formula Reduces Oxidative Stress and Inflammation by Regulating NF-κB in Rats with TNBS-Induced Colitis

We have previously shown that α-linolenic acid (ALA), a (n-3) PUFA exerts in vitro antiinflammatory effects in the intestine. In this study, we aimed to evaluate its effect on inflammatory and oxidative stress in a colitis model. Colitis was induced in 2 groups at d 0 by intrarectal injection of 2-4-6-trinitrobenzen sulfonic acid (TNBS), whereas the control group received the vehicle. Rats we fed 450 mg . kg(-1) . d(-1) of ALA (TNBS+ALA) while the other colitic group (TNBS) and the control group were fed an isocaloric corn oil formula for 14 d (from d -7 to d 7). RBC fatty acid composition was assessed. Oxidative stress was studied by measuring urinary 8-isoprostanes (8-IP) and colon glutathione (GSH) concentration and inducible nitric oxide synthase (iNOS) expression. Colitis was assessed histologically, by production of proinflammatory mediators, including cytokines, leukotrienes B(4) (LTB(4)), and cyclooxygenase-2 (COX-2) and by nuclear factor-κB (NF-κB) activation. The ALA-rich diet significantly increased the RBC levels of ALA, eicosapentaenoic acid, and docosapentaenoic acid (n-3) compared with the TNBS group (P < 0.01 for all). The beneficial effect of ALA supplementation on oxidative stress was reflected by lower urinary 8-IP levels (P < 0.05), a normalized colon GSH concentration (P < 0.01), and reduced colon iNOS expression (P < 0.05) compared with the TNBS group. ALA also protected against colon inflammation as assessed by lower tumor necrosis factor-α secretion and mRNA level (P < 0.05), reduced NF-κB activation (P = 0.01), and lower colon lipid mediator concentrations such as LTB(4) and COX-2 (P < 0.05) compared with the TNBS group. These findings show that an ALA-rich formula is beneficial to TNBS-induced colitic rats via inhibition of oxidative and inflammatory stress.

Prevalence and association of perceived stress, substance use and behavioral addictions: a cross-sectional study among university students in France, 2009--2011

BackgroundUniversity students face multiple stressors such as academic overload, constant pressure to succeed, competition with peers as well as concerns about the future. Stress should not be considered on its own, but should be associated with potential risk behaviors leading to onset of substance use and related problems heightened during the university period. The aim of this study was to determine the prevalence of main substance use and behavioral addictions among students in higher education in France and to examine the relationship with perceived stress.MethodsA self-administered questionnaire was filled out by university student volunteers from Upper Normandy (France) either by anonymous online questionnaire or by paper questionnaire. Data collected included socio-economic characteristics, Perceived Stress Scale (PSS), substance use (tobacco, alcohol, and cannabis) and hazardous behaviors: alcohol abuse problems, smoking, consumption of cannabis, eating disorders, and cyber addiction.ResultsA total of 1876 students were included. Mean PSS score was 15.9 (standard deviation = 7.2). Highly stressed students (4th quartile) were compared with lesser stressed students (1st quartile). A positive relation was observed between female gender, regular smokers, alcohol abuse problems, risk of cyberaddiction and especially eating disorders (AOR = 5.45, 95% CI = 3.42-8.69), and increasing PSS score. PSS score however, was not significantly related to the curriculum, regular alcohol use, drunkenness or binge drinking even after additional controlling for use of other substances. We found a significant negative association between stress and practice of sport: students with the most physical activity were less likely to report perceived stress (4th quartile: AOR = 0.57, 95% CI = 0.39-0.80).ConclusionsThis cross-sectional study among university students in France revealed that perceived stress was associated not only with known risks such as alcohol misuse, but also with new risks such as eating disorders and cyber addiction. These results could help to develop preventive interventions focussing on these risk behaviors and subsequently improving stress coping capacity in this high-risk population.

Dietary modulation of peroxisome proliferator-activated receptor gamma

Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor that regulates intestinal inflammation. PPARγ is highly expressed in the colon and can be activated by various dietary ligands. A number of fatty acids such as polyunsaturated fatty acids or eicosanoids are considered as endogenous PPARγ activators. Nevertheless, other nutrients such as glutamine, spicy food or flavonoids are also able to activate PPARγ. As PPARγ plays a key role in bacterial induced inflammation, anti-inflammatory properties of probiotics may be mediated through PPARγ. The aims of the present review are to discuss of the potential roles of dietary compounds in modulating intestinal inflammation through PPARγ.

Low levels of glutathione in endoscopic biopsies ofpatients with Crohn's colitis: the role of malnutrition

BACKGROUND AND AIMS During active Crohns disease, generation of free radicals is increased, and nutritional depletion is frequent. We investigated the glutathione concentration of the colonic mucosa in biopsies from patients with active Crohns colitis depending on nutritional status. METHODS Endoscopic biopsies were taken in 10 well-nourished control patients, and 18 patients with active Crohns disease (11 well-nourished, seven malnourished with a recent weight loss > 10 %). Colonic biopsies were taken from healthy and inflamed mucosa and analysed for total glutathione concentration. RESULTS Mucosal glutathione concentration (nmol/mg wet tissue) was lower in patients with active colitis both in diseased and healthy mucosa as compared with controls (1.89 +/- 0.39, 2.08 +/- 0.4 and 6.69 +/- 4. 94, respectively, P< 0.05). Mucosal glutathione was lower in healthy mucosa from malnourished versus well-nourished patients: 1.8 +/- 0.2 vs 2.3 +/- 0.37 (P= 0.02). CONCLUSIONS Mucosal glutathione is markedly lower in active Crohns colitis, even in healthy mucosa; glutathione depletion tends to be more severe in malnourished patients. Glutathione depletion may be related in part to malnutrition and contribute to a prolonged evolution of disease and could be a target for pharmacological and nutritional support.

Combined Glutamine and Arginine Decrease Proinflammatory Cytokine Production by Biopsies from Crohn's Patients in Association with Changes in Nuclear Factor-κB and p38 Mitogen-Activated Protein Kinase Pathways

Glutamine (Gln) and arginine (Arg) are conditionally essential amino acids with immunomodulatory properties. The aim of the study was to assess the effects of Gln and Arg alone or in combination on cytokine release by cultured colonic biopsies from patients with active Crohns disease (CD). Ten consecutive patients [mean (range) age 26 (18-39) y] with active colonic CD (mean CD activity index: 383.7 +/- 129.8) were prospectively included in the study. Eight colonic biopsies were obtained via a colonoscopy and incubated during 18 h with low (physiological) or high (pharmacological) doses of Arg (0.1 or 2 mmol/L designated as Arg(low) or Arg(high), respectively) and Gln (0.6 or 10 mmol/L designated as Gln(low) or Gln(high), respectively). The concentrations of cytokines [interleukin (IL)-4, IL-10, IL-8, IL-6, tumor necrosis factor-alpha (TNFalpha), IL-1beta, interferon-gamma) were assessed by ELISA, and nitric oxide (NO) production was evaluated by Griess assay. Nuclear factor (NF)-kappaB p65 subunit, inhibitor of NFkappaB-alpha, and p38 mitogen-activated protein kinase (MAPK) were assessed by immunoblotting. Arg(high)/Gln(high) decreased the production of TNFalpha, IL-1beta, IL-8, and IL-6 (each P < 0.01). Arg(low)/Gln(high) decreased IL-6 and IL-8 production (both P < 0.01), whereas Arg(high)/Gln(low) did not affect cytokine and NO production. Arg(low)/Gln(high) and Arg(high)/Gln(high) decreased NF-kappaB p65 subunit expression, whereas p38 MAPK was decreased only by Arg(high)/Gln(high). Combined pharmacological doses of Arg and Gln decreased TNFalpha and the main proinflammatory cytokines release in active colonic CD biopsies via NF-kappaB and p38 MAPK pathways. These results could be the basis of prospective studies evaluating the effects of enteral supply of combined Arg and Gln during active CD.