Recurrent obstructive apneas trigger early systemic inflammation in a rat model of sleep apnea.

Obstructive sleep apnea (OSA) is associated with vascular disorders possibly due to systemic inflammation. To determine whether repeated episodes of OSA in a rat model lead to endothelial cell activation and systemic leukocyte recruitment in the microcirculation. Three experimental groups (apnea, sham and naive) were studied. The apnea group was instrumented and subjected to repeated obstruction for 3h (rate 60/h, length 5s) using a special device. The sham group was only instrumented and the naive group was used as a control. Leukocyte-endothelial cell interactions (intravital microscopy) and expression of P-selectin (immunohistochemistry) were determined in colonic venules. The apnea group induced a significant increase in the flux of leukocytes rolling, number of rolling leukocytes and number of adherent leukocytes when compared with the sham or naive groups. P-selectin was up-regulated only in the apnea group. This experimental model of recurrent obstruction demonstrates rapid endothelial cell activation, suggesting the onset of an inflammatory response.

Down-regulation of endothelial adhesion molecules and leukocyte adhesion by treatment with superoxide dismutase is beneficial in chronic immune experimental colitis.

Modulation of adhesion molecule expression that govern trafficking of leukocytes into the inflamed intestine is envisioned as a new strategy for treatment of inflammatory bowel disease (IBD). This study was designed to determine the impact of reducing oxidative stress on adhesion molecules expression and leukocyte recruitment in experimental chronic colitis. For that purpose, colitic interleukin-10 knockout and wild-type mice were studied. Groups of animals were treated with Cu/Zn superoxide dismutase (SOD1) 13 mg/kg/d or vehicle for either 7 or 14 days. Expression of vascular cell adhesion molecule-1 and mucosal addressin cell adhesion molecule-1 were determined; leukocyte-endothelial cell interactions in colonic venules were studied with intravital microscopy; and changes in colon pathology and biomarkers of colitis severity were determined. Development of colitis was associated with a marked increase in endothelial vascular cell adhesion molecule-1 and mucosal addressin cell adhesion molecule-1 expression, which were significantly reduced by treatment with SOD1. The increase in leukocyte rolling and adhesion in colonic venules of colitic mice were significantly reduced by administration of SOD1. This treatment markedly reduced colonic lipid hydroperoxidation, myeoloperoxidase activity, and plasma levels of serum amyloid A protein and resulted in significant, although modest, reductions in histologic damage score. The therapeutic value of SOD1 when administered prophylactically was assessed in the dextran sulfate sodium model of colitis with similar positive results. These results indicate that SOD1 affords significant amelioration of colonic inflammatory changes in experimental colitis. Down-regulation of adhesion molecule expression, reduction of lipid hydroperoxidation, and recruitment of leukocytes into the inflamed intestine contribute to this beneficial effect.

Superoxide dismutase ameliorates TNBS-induced colitis by reducing oxidative stress, adhesion molecule expression, and leukocyte recruitment into the inflamed intestine.

Oxidant stress has been implicated in the pathogenesis of inflammatory bowel disease. Antioxidant enzymes, such as superoxide dismutase (SOD), are candidate drugs for modulating this pathogenic factor. This study was designed to determine the therapeutic value of SOD in an experimental model of colitis and to study the mechanisms underlying its effects on intestinal inflammation. For that purpose, colitic (trinitrobenzene sulfonic acid-induced) and control rats were studied. Groups of colitic animals were treated with different doses of SOD (1, 4, or 13 mg/kg/day) or vehicle, starting after induction of colitis and during 7 days. Clinical and pathological markers of colitis severity and lipid peroxidation in colonic tissue were measured. Leukocyte-endothelial cell interactions in colonic venules and expression of vascular cell adhesion molecule 1 (VCAM-1) were determined. Development of colitis was associated with a significant loss in body weight, an increase in macroscopic and microscopic damage scores, and colonic myeloperoxidase activity. Administration of SOD significantly attenuated these changes in a dose-dependent manner and reduced lipid peroxidation in colonic tissue. The increase in leukocyte rolling and adhesion in colonic venules of colitic rats were significantly reduced by administration of SOD, 13 mg/kg/day. Development of colitis was associated with a marked increase in endothelial VCAM-1 expression, which was significantly reduced by treatment with SOD. In conclusion, treatment with SOD significantly reduces peroxidation reactions in the inflamed colon and affords significant amelioration of colonic inflammatory changes in experimental colitis. This effect is related to a reduction in VCAM-1 expression and leukocyte recruitment into the inflamed intestine.