Hindlimb Ischemia/Reperfusion-Induced Remote Injury to the Small Intestine: Role of Inducible Nitric-Oxide Synthase-Derived Nitric Oxide

Abstract

Systemic inflammatory response syndrome, as a consequence of ischemia/reperfusion (I/R), negatively influences the function of the affected organs. The objective of this study was to assess the role of nitric oxide (NO) in remote intestinal inflammatory response elicited by hindlimb I/R. To this end, C57BL/6 (wild type; WT) and inducible nitric-oxide synthase (iNOS)-deficient mice were subjected to bilateral hindlimb ischemia (1 h) followed by 6 h of reperfusion. Some WT mice were injected with iNOS inhibitor N- [3-(aminomethyl)benzyl] acetamidine (1400W) (5 mg/kg s.c.) immediately before reperfusion, and proinflammatory response was assessed 6 h later. Hindlimb I/R resulted in dysfunction of the small intestine as assessed by the increase in permeability [blood-to-lumen clearance of Texas Red-dextran (molecular mass 3 kDa)] and an increase in the luminal levels of tumor necrosis factor (TNF)-␣ protein and nitrate/nitrite (NO 2 Ϫ /NO 3 Ϫ ). The above-mentioned changes were accompanied by up-regulation of the proinflammatory phenotype in the mucosa of small intestine with respect to 1) an increase in TNF-␣ and iNOS protein expression, 2) leukocyte accumulation, 3) formation of edema, 4) an increase in leukocyte rolling/adhesion in the submucosal microvasculature, and 5) activation of transcription factor nuclear factor-B and upregulation of adhesion molecule expression. Interestingly, the most profound changes with respect to intestinal dysfunction were found in jejunum and ileum, whereas duodenum was affected the least. Interfering with iNOS activity (1400W and iNOS-deficient mice) significantly attenuated hindlimb I/R-induced inflammatory response and dysfunction of the small intestine with respect to the above-mentioned markers of inflammation. The obtained results indicate that hindlimb I/R induces remote inflammatory response in the small intestine through an iNOS-derived NO-dependent mechanism.

iNOS as a Driver of Inflammation and Apoptosis in Mouse Skeletal Muscle after Burn Injury: Possible Involvement of Sirt1 S-Nitrosylation-Mediated Acetylation of p65 NF-κB and p53

“…Conversely, iNOS is capable of both enhancing and inhibiting NF-κB activity [16]. In most, but not all, rodent models of inflammatory human diseases, including ischemia-reperfusion injury, inhibition of iNOS by gene disruption or pharmacological inhibitors decreases NF-κB activity [40–43]. However, the underlying mechanisms by which iNOS increases NF-κB activity were not fully understood.…”

Carbon Monoxide Liberated from CO-Releasing Molecule (CORM-2) Attenuates Ischemia/Reperfusion (I/R)-Induced Inflammation in the Small Intestine

“…Intravital microscopy of mice small intestine was performed as previously described by us [27]. Briefly, following 4 h of reperfusion, mice were re-anesthetized and the abdomen was opened via a longitudinal midline incision.…”

“…The flux of rolling and the number of adherent leukocytes were determined by offline video playback analysis as previously described [27]. Vessel length and diameter were measured offline with ImageJ software.…”

The Role of L‐Arginine and Inducible Nitric Oxide Synthase in Intestinal Permeability and Bacterial Translocation

“…Treatment of endotoxemic rats with selective iNOS inhibitors prevented acidosis, restored mean arterial pressure, and ameliorated gut mucosal barrier dysfunction 12 , 13 . In ischemia/reperfusion models, the selective inhibition of iNOS also showed positive effects, such as a decrease of edema and leukocyte rolling/ adhesion and attenuation of gut mucosal injury 14 – 16 . On the other hand, congenic iNOS knockout mice exhibited increased inflammation and mucosal injury under colitis conditions 17 , 18 .…”