Tim Lubbers

Lipid-rich enteral nutrition reduces postoperative ileus in rats via activation of cholecystokinin-receptors

Objective:This study investigates the effect of lipid-rich nutrition on the local inflammatory response and gastrointestinal hypomotility in a rat model of postoperative ileus. Background:Postoperative ileus is a major clinical problem, in which inflammation of the intestinal muscularis plays a key pathogenic event. Previously, administration of lipid-rich nutrition has been shown to reduce inflammation by activation of the autonomic nervous system via cholecystokinin-receptors. Methods:Postoperative ileus was induced by manipulation of the small intestine in rats. Peritoneal lavage fluid, plasma, and jejunal segments were collected at several time points to determine inflammatory mediators in fasted rats and rats fed a lipid-rich or control nutrition. Gastrointestinal transit was measured 24 hours after surgery. Results:Administration of lipid-rich nutrition markedly reduced the manipulation-induced local inflammatory response compared to rats treated with control nutrition. The intervention with lipid-rich nutrition significantly reduced plasma levels of rat mast cell protease-II (P < 0.05) and peritoneal levels of tumor necrosis factor-alpha (P < 0.01) and interleukin-6 (P < 0.05). Furthermore, the influx of neutrophils, expressed as tissue level myeloperoxidase was significantly prevented by lipid-rich nutrition (P < 0.05). Above all administration of lipid-rich enteral nutrition resulted in a significant improvement of gastrointestinal transit compared to control nutrition (P < 0.05). Blocking of cholecystokinin-receptors prevented the anti-inflammatory and motility promoting effect of lipid-rich feeding. Conclusion:Our data demonstrate that nutritional stimulation of the autonomic nervous system with enteral lipids reduces postoperative ileus by inhibition of inflammation. Clinically, lipid-rich enteral nutrition may be a new therapeutic option in the treatment of postoperative ileus.

Cholecystokinin/Cholecystokinin-1 receptor-mediated peripheral activation of the afferent vagus by enteral nutrients attenuates inflammation in rats.

Objective:The current study investigates activation of the nutritional anti-inflammatory pathway by lipid-rich nutrition. Background:Enteral nutrition activates humoral and neural pathways to regulate food intake and sustain energy balance. Recently, we demonstrated that enteral nutrition and in particular lipid-rich nutrition modulates inflammation and prevents organ damage. Methods:Male rats were fasted or fed lipid-rich nutrition before hemorrhagic shock. Disruption of afferent vagal fibers with capsaicin (deafferentation) was used to investigate involvement of afferent fibers. Peripheral activation of afferent vagal fibers via cholecystokinin (CCK)-mediated activation of CCK-1 receptors was investigated using administration of the selectively peripheral acting CCK-1 receptor antagonist, A70104 and PEGylated-CCK9. Tissue and blood were collected 90 minutes after shock to assess systemic inflammation and intestinal integrity. Results:Deafferentation reversed the inhibitory effect of lipid-rich nutrition on systemic levels of tumor necrosis factor-&agr; and interleukin-6, and on intestinal leakage of horseradish peroxidase and bacterial translocation. Furthermore, the protective effects of lipid-rich nutrition were negated by A70104, indicating that lipid-rich nutrition triggers peripheral CCK-1 receptors on vagal afferents to modulate inflammation. These findings were substantiated by the fact that pretreatment of fasted rats with PEGylated-CCK9, which acts on peripheral CCK-1 receptors, attenuated systemic inflammation, and loss of intestinal integrity. Conclusion:These data demonstrate that enteral lipid-rich nutrition modulates inflammation and preserves intestinal integrity via CCK release which activates CCK-1 receptors located on afferent vagal fibers. Taken together, the current study reveals a novel gut-brain-immune axis and provides new insight into the applicability of enteral nutrition to treat inflammatory conditions.

Rapid development of intestinal cell damage following severe trauma: a prospective observational cohort study

IntroductionLoss of intestinal integrity has been implicated as an important contributor to the development of excessive inflammation following severe trauma. Thus far, clinical data concerning the occurrence and significance of intestinal damage after trauma remain scarce. This study investigates whether early intestinal epithelial cell damage occurs in trauma patients and, if present, whether such cell injury is related to shock, injury severity and the subsequent inflammatory response.MethodsProspective observational cohort study in 96 adult trauma patients. Upon arrival at the emergency room (ER) plasma levels of intestinal fatty acid binding protein (i-FABP), a specific marker for damage of differentiated enterocytes, were measured. Factors that potentially influence the development of intestinal cell damage after trauma were determined, including the presence of shock and the extent of abdominal trauma and general injury severity. Furthermore, early plasma levels of i-FABP were related to inflammatory markers interleukin-6 (IL-6), procalcitonin (PCT) and C-reactive protein (CRP).ResultsUpon arrival at the ER, plasma i-FABP levels were increased compared with healthy volunteers, especially in the presence of shock (P < 0.01). The elevation of i-FABP was related to the extent of abdominal trauma as well as general injury severity (P < 0.05). Circulatory i-FABP concentrations at ER correlated positively with IL-6 and PCT levels at the first day (r2 = 0.19; P < 0.01 and r2 = 0.36; P < 0.001 respectively) and CRP concentrations at the second day after trauma (r2 = 0.25; P < 0.01).ConclusionsThis study reveals early presence of intestinal epithelial cell damage in trauma patients. The extent of intestinal damage is associated with the presence of shock and injury severity. Early intestinal damage precedes and is related to the subsequent developing inflammatory response.

Postshock intervention with high-lipid enteral nutrition reduces inflammation and tissue damage

Objective:To investigate the effects of high-lipid enteral nutrition in a setting of developing inflammation and tissue damage. Background:An excessive inflammatory response following severe trauma is associated with poor clinical outcome. Currently, therapies directed at attenuation of an ongoing inflammatory cascade are lacking. Administration of high-lipid enteral nutrition before hemorrhagic shock has been shown to effectively inhibit early and late proinflammatory cytokines by activation of the autonomic nervous system via cholecystokinin (CCK)-receptors. Methods:A rat model of hemorrhagic shock was used in which animals were either fasted or treated with high-lipid or control low-lipid enteral nutrition. CCK-receptor antagonists were administered before feeding. Tissues and plasma were collected to assess inflammation and intestinal integrity. Results:Administration of high-lipid enteral nutrition after shock reduced plasma interferon-gamma (IFN-γ) significantly in comparison with those in low-lipid-treated and fasted animals (P < 0.01 and P < 0.001, respectively). Also, interleukin (IL)-10 levels in plasma were decreased in comparison with those in fasted animals (P < 0.001). Enterocyte damage, expressed as circulating ileal lipid-binding protein (ILBP), was prevented by early high-lipid nutrition in comparison with that in low-lipid-treated and fasted animals (P = 0.05 and P < 0.001, respectively). Furthermore, high-lipid feeding preserved intestinal integrity in comparison with that observed in low-lipid-treated and fasted animals, as assessed by bacterial translocation (BT) to distant organs (P < 0.05 and P < 0.001, respectively) and ileal permeability to horseradish peroxidase (HRP) (P = 0.05 and P < 0.001, respectively). The protective effects of high-lipid intervention were nullified by CCK-receptor antagonists (IFN-γ; IL-10; BT; and HRP; P < 0.05). Conclusion:High-lipid enteral nutrition given postshock reduces inflammation and preserves tissue integrity via a CCK-receptor-dependent mechanism. These findings implicate that intervention with high-lipid enteral nutrition following events such as severe trauma is a potential therapy to attenuate the developing inflammatory response.

Lipid-enriched enteral nutrition controls the inflammatory response in murine Gram-negative sepsis.

Objectives:Controlling the inflammatory cascade during sepsis remains a major clinical challenge. Recently, it has become evident that the autonomic nervous system reduces inflammation through the vagus nerve. The current study investigates whether nutritional stimulation of the autonomic nervous system effectively attenuates the inflammatory response in murine Gram-negative sepsis. Design:Controlled in vivo and ex vivo experimental study. Settings:Research laboratory of a university hospital. Subjects:Male C57bl6 mice. Interventions:Mice were intraperitoneally challenged with lipopolysaccharide derived from Escherichia coli. Before lipopolysaccharide administration, mice were fasted or enterally fed either lipid-rich nutrition or low-lipid nutrition. Antagonists to cholecystokinin receptors or nicotinic receptors were administered before lipopolysaccharide administration. Blood and tissue samples were collected at 90 mins. Mesenteric afferent discharge was determined in ex vivo preparations in response to both nutritional compositions. Measurements and Main Results:Both lipid-rich and low-lipid nutrition dose-dependently reduced lipopolysaccharide-induced tumor necrosis factor-&agr; release (high dose: both 1.4 ± 0.4 ng/mL) compared with fasted mice (3.7 ± 0.8 ng/mL; p < .01). The anti-inflammatory effect of both nutritional compositions was mediated through cholecystokinin receptors (p < .01), activation of mesenteric vagal afferents (p < .05), and peripheral nicotinic receptors (p < .05). Lipid-rich nutrition attenuated the inflammatory response at lower dosages than low-lipid nutrition, indicating that enrichment of enteral nutrition with lipid augments the anti-inflammatory potential. Administration of lipid-rich nutrition prevented endotoxin-induced small intestinal epithelium damage and reduced inflammation in the liver and spleen compared with fasted (all p < .01) and low-lipid nutrition controls (all p < .05). Conclusions:The current study demonstrates that lipid-rich nutrition attenuates intestinal damage and systemic as well as organ-specific inflammation in murine Gram-negative sepsis through the nutritional vagal anti-inflammatory pathway. These findings implicate enteral administration of lipid-enriched nutrition as a promising intervention to modulate the inflammatory response during septic conditions.

Protection against early intestinal compromise by lipid-rich enteral nutrition through cholecystokinin receptors.

Objective:Early gut wall integrity loss and local intestinal inflammation are associated with the development of inflammatory complications in surgical and trauma patients. Prevention of these intestinal events is a potential target for therapies aimed to control systemic inflammation. Previously, we demonstrated in a rodent shock model that lipid-rich enteral nutrition attenuated systemic inflammation and prevented organ damage through a cholecystokinin receptor-dependent vagal pathway. The influence of lipid-rich nutrition on very early intestinal compromise as seen after shock is investigated. Next, the involvement of cholecystokinin receptors on the nutritional modulation of immediate gut integrity loss and intestinal inflammation is studied. Design:Randomized controlled in vivo study. Setting:University research unit. Subjects:Male Sprague-Dawley rats. Interventions:Liquid lipid-rich nutrition or control low-lipid feeding was administered per gavage before hemorrhagic shock. Cholecystokinin receptor antagonists were used to investigate involvement of the vagal antiinflammatory pathway. Measurements and Main Results:Gut permeability to horseradish peroxidase increased as soon as 30 mins postshock and was prevented by lipid-rich nutrition compared with low-lipid (p < .01) and fasted controls (p < .001). Furthermore, lipid-rich nutrition reduced plasma levels of enterocyte damage marker ileal lipid binding protein at 60 mins (p < .05). Early gut barrier dysfunction correlated with rat mast cell protease plasma concentrations at 30 mins (rs = 0.67; p < .001) and intestinal myeloperoxidase levels at 60 mins (rs = 0.58; p < .05). Lipid-rich nutrition significantly reduced plasma rat mast cell protease (p < .01) and myeloperoxidase (p < .05) before systemic inflammation was detectable. Protective effects of lipid-rich nutrition were abrogated by cholecystokinin receptor antagonists (horseradish peroxidase; p < .05 and rat mast cell protease; p < .05). Conclusions:Lipid-rich enteral nutrition prevents early gut barrier loss, enterocyte damage, and local intestinal inflammation before systemic inflammation develops in a cholecystokinin receptor-dependent manner. This study identifies activation of the vagal antiinflammatory pathway with lipid-rich nutrition as a potential therapy in patients prone to develop a compromised gut.

Continuous administration of enteral lipid- and protein-rich nutrition limits inflammation in a human endotoxemia model

Objective:An overzealous inflammatory response is an important cause of morbidity and mortality in surgical, trauma, and critically ill patients. Enteral administration of lipid-rich nutrition was previously shown to attenuate inflammation and reduce organ damage via a cholecystokinin-1 receptor–mediated vagovagal reflex in animal studies. The current preclinical study investigates the immunomodulatory potential of a custom-made enteral nutrition during systemic inflammation in man. Design:Double-blind, randomized controlled trial. Setting:Intensive care research unit. Subjects:Male volunteers. Interventions:After an overnight fast, 18 healthy male subjects received an IV bolus of Escherichia coli lipopolysaccharide (2 ng/kg). Subjects in the fasted group (n = 6) were deprived of food throughout the study, while subjects in the intervention groups were fed either custom-made lipid- and protein-rich nutrition (n = 6) or isocaloric control nutrition (n = 6) via nasojejunal tube, starting 1 hour prior to lipopolysaccharide administration until 6 hours afterward. Measurements and Main Results:Bolus lipopolysaccharide administration resulted in a marked inflammatory response. Continuous postpyloric administration of nutrition significantly increased plasma cholecystokinin levels throughout the lipopolysaccharide-induced inflammatory response. Lipid- and protein-rich nutrition attenuated circulating levels of the proinflammatory cytokines tumor necrosis factor-&agr; and interleukin-6 and the interleukin-1 receptor antagonist compared with control nutrition (all p < 0.05) and fasted subjects (all p < 0.05). In additional, lipid- and protein-rich nutrition augmented the anti-inflammatory response, reflected by increased plasma levels of interleukin-10 compared with fasted subjects (p < 0.0001). Conclusions:The current preclinical study expands the immunomodulating effects of enteral nutrition as previously observed in rodents to man. Continuous administration of enteral nutrition resulted in a rapid anti-inflammatory effect. Furthermore, enrichment of the nutritional composition with lipid and protein was shown to enhance the anti-inflammatory potential. Therefore, continuous enteral administration of lipid- and protein-rich nutrition is a promising intervention to modulate the immune response in the early course of systemic inflammation in man.

Lipid-rich enteral nutrition regulates mucosal mast cell activation via the vagal anti-inflammatory reflex

Nutritional stimulation of the cholecystokinin-1 receptor (CCK-1R) and nicotinic acetylcholine receptor (nAChR)-mediated vagal reflex was shown to reduce inflammation and preserve intestinal integrity. Mast cells are important early effectors of the innate immune response; therefore modulation of mucosal mast cells is a potential therapeutic target to control the acute inflammatory response in the intestine. The present study investigates intestinal mast cell responsiveness upon nutritional activation of the vagal anti-inflammatory reflex during acute inflammation. Mucosal mast cell degranulation was induced in C57/Bl6 mice by administration of Salmonella enterica LPS. Lipid-rich enteral feeding prior to LPS significantly decreased circulatory levels of mouse mast cell protease at 30 min post-LPS compared with isocaloric low-lipid nutrition or fasting. CCK-1R blockage reversed the inhibitory effects of lipid-rich feeding, whereas stimulation of the peripheral CCK-1R mimicked nutritional mast cell inhibition. The effects of lipid-rich nutrition were negated by nAChR blockers chlorisondamine and α-bungarotoxin and vagal intestinal denervation. Accordingly, release of β-hexosaminidase by MC/9 mast cells following LPS or IgE-ovalbumin complexes was dose dependently inhibited by acetylcholine and nicotine. Application of GSK1345038A, a specific agonist of the nAChR α7, in bone marrow-derived mast cells from nAChR β2-/- and wild types indicated that cholinergic inhibition of mast cells is mediated by the nAChR α7 and is independent of the nAChR β2. Together, the present study reveals mucosal mast cells as a previously unknown target of the nutritional anti-inflammatory vagal reflex.

Chylomicron formation and glucagon-like peptide 1 receptor are involved in activation of the nutritional anti-inflammatory pathway

Enteral administration of lipid-enriched nutrition effectively attenuates inflammation via a cholecystokinin (CCK)-mediated vagovagal anti-inflammatory reflex. Cholecystokinin release and subsequent activation of the vagus are dependent on chylomicron formation and associated with release of additional gut peptides. The current study investigates the intestinal processes underlying activation of the CCK-mediated vagal anti-inflammatory pathway by lipid-enriched nutrition. Rats and mice were subjected to hemorrhagic shock (HS) or endotoxemia, respectively. Prior to the experimental procedures, animals were fasted or fed lipid-enriched nutrition. Pluronic L-81 (L-81) was added to the feeding to investigate involvement of chylomicron formation in activation of mesenteric afferent fibers and the immune-modulating potential of lipid-enriched nutrition. Ob/Ob mice and selective receptor antagonists were used to study the role of leptin, glucagon-like peptide 1 and peptide YY in activation of the nutritional reflex. Electrophysiological analysis of mesenteric afferents in mice revealed that lipid-enriched nutrition-mediated neural activation was abrogated by L-81 (P<.05). L-81 blunted the beneficial effects of lipid-enriched nutrition on systemic inflammation and intestinal integrity in both species (all parameters, P<.01). Ob/Ob mice required a higher dose of nutrition compared with wild-type mice to attenuate plasma levels of TNF-α and ileum-lipid binding protein, a marker for enterocyte damage (both P<.01), suggesting a higher stimulation threshold in leptin-deficient mice. Administration of a glucagon-like peptide 1-receptor antagonist, but not leptin or peptide YY antagonists, suppressed the effects of lipid-enriched nutrition. These data indicate that chylomicron formation is essential and activation of the glucagon-like peptide 1-receptor is involved in activation of the nutritional anti-inflammatory pathway by lipid-enriched nutrition.

Lipid-rich enteral nutrition improves the defense against an opportunistic infection during polymicrobial sepsis

ABSTRACT The development of an immunosuppressive state during the protracted course of sepsis is associated with opportunistic infections and is considered to correlate with the extent of the proinflammatory response during early sepsis. Short-term intervention with enteral lipid-rich nutrition was shown to attenuate the acute inflammatory response. This study investigates the effects of lipid-rich nutrition on the immunosuppression induced by polymicrobial sepsis. Female BALB/c mice were either fasted or fed liquid lipid-rich nutrition or isocaloric control nutrition before and shortly after induction of polymicrobial sepsis through cecal ligation and puncture (CLP) or sham operation. After 4 days, mice were intranasally infected with Pseudomonas aeruginosa. Twenty-four hours after P. aeruginosa infection, fasted and control nutrition-fed CLP mice displayed a significantly higher bacterial load in the lungs than did corresponding sham-operated mice (P < 0.001 and P < 0.05, respectively). Fasted CLP mice expressed reduced pulmonary levels of proinflammatory cytokines interleukin 12 (IL-12) and interferon &ggr; (IFN-&ggr;) in comparison to sham mice (both P < 0.05). Lipid-rich nutrition prevented the increase in bacteria, promoted the IL-12 and IFN-&ggr; production (IL-12 and IFN-&ggr; [P < 0.05] vs. fasted and IFN-&ggr; [P < 0.05] vs. control nutrition), and prevented the expression of the immunosuppressive cytokine IL-10 (P < 0.05 vs. control nutrition) in lungs of CLP mice. The preserved immune defense during late sepsis in lipid-rich fed mice was preceded by attenuation of the early inflammatory response (IL-6 [P = 0.05] and IL-10 [P < 0.01] vs. fasted CLP mice) at 6 h after CLP. In conclusion, short-term treatment with lipid-rich enteral nutrition improves the pulmonary antimicrobial defense during polymicrobial sepsis.