Inflammatory mediators of experimental colitis in rats

Area of Science:

• Gastroenterology
• Inflammation Research
• Animal Models

Background:

• Colonic inflammation models are crucial for studying inflammatory bowel disease.
• The trinitrobenzene sulfonic acid (TNB) model is widely used but requires refinement.
• Investigating the role of specific inflammatory mediators is essential for understanding disease progression.

Purpose of the Study:

• To establish and characterize a rat model of chronic colonic inflammation using TNB/ethanol.
• To evaluate the reliability of myeloperoxidase (MPO) activity and Interleukin-1 (IL-1) as indicators of inflammation.
• To explore the involvement of leukotriene B4 (LTB4) and thromboxane B2 (TXB2) in acute and chronic inflammatory responses.

Main Methods:

• Colonic inflammation was induced in rats using intracolonic administration of TNB in ethanol or saline.
• Control groups received ethanol or saline alone.
• Macroscopic and microscopic injury, MPO activity, IL-1, LTB4, TXB2, and platelet-activating factor (PAF) were assessed at 24 hours, 1 week, and 3 weeks.

Main Results:

• The TNB/ethanol model induced persistent mucosal ulceration and hemorrhage, progressing to chronic active inflammation.
• MPO activity and IL-1 levels were significantly elevated, correlating with observed mucosal injury.
• LTB4 levels increased in TNB/ethanol-treated rats, particularly at 1 week, indicating its role in chronic inflammation, while TXB2 was reduced.

Conclusions:

• The TNB/ethanol model provides a reliable method for inducing chronic gut inflammation in rats.
• MPO activity and IL-1 are sensitive and reliable biomarkers for assessing colonic inflammation in this model.
• LTB4 is implicated in the chronic inflammatory response, whereas TXB2 is not involved in acute lesions.