Effects of ischemia and reperfusion on production of nitrotyrosine, activation of eosinophils, and apoptosis in the large colonic mucosa of horses.

The research paper focuses on exploring the impact of interrupted blood supply and its restoration (ischemia and reperfusion) on measures of oxidative stress, trigger of eosinophils, and cell death (apoptosis) in the large colon of horses.

Research Methodology

• The researchers conducted the experiment involving 40 horses. To induce ischemia (loss of blood supply), they selected one or two segments of the large colon in these anesthetized horses.
• Specifically, they selected segments that were 20-cm-long on the pelvic flexure for the experiment.
• They created conditions of no blood supply for 1 or 2 hours in these segments, followed by no reperfusion or reperfusion for 30 mins and 18 hours (reperfusion refers to the restoration of blood supply).
• Colonic mucosal specimens were collected both before the procedure (controls, n=20 horses) and after each ischemia period. They also collected full-thickness tissue samples after each reperfusion period.
• They further stained sections of the colonic tissues for histomorphometric analysis or for checking accumulation of eosinophils, a type of white blood cells that play significant roles in combating infections and triggering inflammation.
• They detected nitrotyrosine (a biomarker for understanding oxidative stress condition in a biological system) immunohistochemically, and quantified the severity of apoptosis (programmed cell death) via the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method.

Key Findings

• The numbers of collagen-rich mucosal eosinophils were observed to be similar before the induction of ischemia, after ischemia and post ischemia-reperfusion.
• Notably, the production of eosinophil nitrotyrosine increased significantly during ischemia and persisted for 30 minutes of reperfusion.
• The production of nitrotyrosine decreased at 18 hours of reperfusion but was still higher compared to the control group.
• In the case of other leukocytes (white blood cells), nitrotyrosine production peaked at 1 hour of ischemia and again at 18 hours of reperfusion.
• Compared to control findings, the researchers observed a gradual increase in epithelial apoptosis from 1 to 2 hours of ischemia without further progression after reperfusion.

Conclusion

• The research results indicated that resident eosinophils located in the large colon of horses react to mucosal injury caused by ischemia and reperfusion.
• These eosinophils may undergo oxidative stress under such circumstances.
• The data also suggested that epithelial apoptosis could contribute to the tissue damage observed.