Immunoregulation of endometrial and jejunal epithelia sensitized by infection

Resuscitation-induced gut edema and intestinal dysfunction

BACKGROUND

Mesenteric venous hypertension and subsequent gut edema play a pivotal role in the development of intra-abdominal hypertension. Although gut edema is one cause of intra-abdominal hypertension, its impact on gut function is unknown. The purpose of this study was to create a model of acute hydrostatic gut edema and to evaluate its effect on gut motility and barrier function.

METHODS

The first study, group A, evaluated the effect of gut edema on transit over time using 20 mL/kg 0.9% saline. The second study, group B, focused on the 12-hour time period using 80 mL/kg 0.9% saline. Rats were randomized to superior mesenteric vein partial occlusion (venous hypertension) or sham surgery. At 6, 12, and 24 hours, group A underwent intestinal transit and tissue water weight measurements. At 12 hours, group B underwent tissue water, transit, ileal permeability and resistance, lactate and myeloperoxidase activity, and mucosal injury measurements.

RESULTS

Venous hypertension with fluid resuscitation caused acute hydrostatic gut edema, delayed intestinal transit, increased mucosal permeability to macromolecules, and decreased tissue resistance over time. Mucosal injury was minimal in mesenteric venous hypertension.

CONCLUSION

Acute mesenteric venous hypertension and resuscitation-induced gut edema, in the absence of ischemia/reperfusion injury, is associated with delayed intestinal transit and altered gut barrier function.

Helminth regulation of host IL-4Ralpha/Stat6 signaling: mechanism underlying NOS-2 inhibition by Trichinella spiralis

Gastrointestinal nematode infection is known to alter host T cell activation and has been used to study immune and inflammatory reactions in which nitric oxide (NO) is a versatile player. We previously demonstrated that Trichinella spiralis infection inhibits host inducible NO synthase (NOS-2) expression. We now demonstrate that (i) an IL-4 receptor alpha-subunit (IL-4Ralpha)/Stat6-dependent but T cell-independent pathway is the key for the nematode-induced host NOS-2 inhibition; (ii) endogenous IL-4 and IL-13, the only known IL-4Ralpha ligands, are not required for activating the pathway; and (iii) treatment of RAW264.7 cells with parasite-cultured medium inhibits NOS-2 expression but not cyclooxygenase 2 expression. We propose that a yet-unidentified substance is released by the nematode during the host-parasite interaction.

Ileal mucosal response to bacterial toxin challenge

BACKGROUND

The cause of postinjury intestinal mucosal barrier disruption remains obscure. The present study examines the hypothesis that the bacterial toxin formyl-methionyl leucyl phenylalanine (FMLP) plays an initial role in this process.

METHODS

Mucosal permeability to fluorescein isothiocyanate-labeled dextran (4,400 molecular weight) was measured in perfused distal rat ileum with and without FMLP. Dextran and myeloperoxidase appearance in the lumenal perfusate was assessed in response to surrogates of traumatic stress: ischemia/reperfusion, total abdominal irradiation, and total parenteral nutrition. Recovery of FMLP in the effluent of static closed and perfused ileal loops was determined by mass spectrometry. Release of mast cell mediators in the presence of FMLP was determined in ileal everted sacs.

RESULTS

Seventy-five percent of FMLP was recovered in perfusion effluent in contrast to 5% in closed loops. There was a transient increase in ileal permeability in FMLP/perfused, untreated rats, and in ischemia/reperfusion and total parenteral nutrition treated rats that was recorded with a concomitant increment in myeloperoxidase (inflammatory marker) in all experimental models except irradiated rats, which were unresponsive to FMLP. FMLP responsiveness was associ. ated with a significant rise in release of serotonin (mast cell mediator).

CONCLUSION

These results suggest that mast cells and other resident inflammatory cells within the gut wall are involved in FMLP-induced changes in mucosal barrier permeability and raise the possibility that under conditions of traumatic stress, proinflammatory mediators within the gut wall might be activated by toxic factors in the gut lumen.