Beneficial Effects of Anti-Interleukin-6 Antibodies on Impaired Gastrointestinal Motility, Inflammation and Increased Colonic Permeability in a Murine Model of Sepsis Are Most Pronounced When Administered in a Preventive Setup.

BACKGROUND AND OBJECTIVES: During sepsis, gastrointestinal ileus, mucosal barrier dysfunction and bacterial translocation are accepted to be important triggers that can maintain or exacerbate the septic state. In the caecal ligation and puncture animal model of sepsis, we demonstrated that systemic and colonic interleukin-6 levels are significantly increased coinciding with an impaired colonic barrier function. We therefore aimed to study the effect of therapeutic or curative administration of anti-IL6 antibodies on overall GI motility, colonic permeability and translocation of intestinal bacteria in blood and mesenteric lymph nodes in the mouse caecal ligation and puncture model. METHODS: OF-1 mice were randomized to either the preventive or curative protocol, in which they received 1 mg/kg of antibodies to interleukin-6, or its IgG isotype control solution. They subsequently underwent either the caecal ligation and puncture procedure, or sham-surgery. GI motility was assessed 48 h following the procedure, as well as colonic permeability, serum and colon cytokines, colonic tight junction proteins at the mRNA level; cultures of blood and mesenteric lymph nodes were performed. RESULTS: Preventive administration of anti-interleukin-6 antibodies successfully counteracted the gastrointestinal motility disturbances and impaired colonic barrier function that could be observed in vehicle-treated septic animals. Serum and colonic levels of proinflammatory cytokines were significantly lower when animals were preventively treated with anti-interleukin-6 antibodies. A repetitive injection 24 h later resulted in the most pronounced effects. Curative treatment significantly lowered systemic and colonic inflammation markers while the effects on transit and permeability were unfortunately no longer significant. CONCLUSIONS: Caecal ligation and puncture resulted in septic ileus with an increased colonic permeability. Antibodies to interleukin-6 were able to ameliorate gastro-intestinal motility, suppress inflammation and normalize the permeability of the colonic wall, with the preventive administration combined with a repeat injection being far more efficacious than the sole preventive or curative one.

EFFECT OF GTS-21, AN ALPHA7 NICOTINIC ACETYLCHOLINE RECEPTOR AGONIST, ON CLP-INDUCED INFLAMMATORY, GASTROINTESTINAL MOTILITY, AND COLONIC PERMEABILITY CHANGES IN MICE.

BACKGROUND: During abdominal sepsis, the inhibition of gastrointestinal (GI) motility together with mucosal barrier dysfunction will lead to increased bacterial translocation and maintenance of sepsis. The activation of the vagal anti-inflammatory pathway remains an appealing therapeutic strategy in sepsis. In this respect, selective alpha7 nicotinic acetylcholine receptor (α7nAChR) agonists have shown anti-inflammatory properties in several animal models of inflammation. METHODS: Sepsis was induced in OF-1 mice by cecal ligation and puncture (CLP). GI transit was quantified, and cytokine levels were determined in serum and colon. Colonic permeability was assessed by means of Evans blue injection. We studied the effect of GTS-21, an α7nAChR agonist, on the aforementioned parameters. Splenectomized animals as well as α7nAChR-knock-out animals (Chrna7) were included to study the role of splenic macrophages and the α7nAChR during polymicrobial abdominal sepsis. RESULTS: In septic animals, GTS-21 significantly ameliorated GI motility, lowered systemic and colonic levels of IL-6, decreased colonic permeability, and decreased the number of positive cultures obtained from blood and mesenteric lymph nodes. Splenectomy prevented animals from developing sepsis-induced ileus. Chrna7 mice displayed a more severe septic phenotype, whereas GTS-21 remarkably was also beneficial in these animals. CONCLUSION: Our results show that peripheral targeting of the vagal anti-inflammatory pathway proves beneficial in an animal model of polymicrobial abdominal sepsis. A major role is allocated to splenic immune cells in the development of sepsis, as preventive splenectomy was protective for the development of sepsis. Data on the Chrna7 mice suggest that the beneficial effects mediated by GTS-21 on inflammation and motility might be related to activation of other receptors besides the α7nAChR.