EP2 Receptor Blockade Attenuates COX-2 Upregulation During Intestinal Inflammation.

Area of Science:

• Gastroenterology
• Inflammation Research
• Molecular Biology

Background:

• Prostaglandin E2 (PGE2) has dual roles in intestinal health, promoting homeostasis at low levels and contributing to pathology like necrotizing enterocolitis (NEC) at high levels.
• The concentration-dependent effects of PGE2 are mediated by EP1-EP4 receptors, with EP1 and EP2 considered pro-inflammatory.

Purpose of the Study:

• To investigate the role of EP1 and EP2 receptors in regulating cyclooxygenase-2 (COX-2) expression and gut barrier function during intestinal inflammation.
• To evaluate the therapeutic potential of blocking EP1 and EP2 receptors in models of intestinal injury.

Main Methods:

• Utilized cultured enterocytes (IEC-6) and three distinct animal models of intestinal injury (neonatal rat NEC, adult mouse endotoxemia, cecal ligation/puncture).
• Administered EP1, EP2, and EP4 receptor antagonists (ONO-8711, PF-04418948, E7046, respectively) and a COX-2 inhibitor (Celecoxib).
• Assessed COX-2 mRNA and protein expression, and evaluated pathology in NEC models.

Main Results:

• PGE2 upregulated COX-2 in enterocytes, an effect blocked by the EP2 antagonist PF-04418948 but not EP1 or EP4 antagonists.
• In the NEC model, EP2 antagonist and low-dose Celecoxib reduced NEC pathology and COX-2 expression; EP1 antagonist had no effect.
• EP2 deficiency, but not EP1 deficiency, decreased intestinal COX-2 expression in adult mouse models of inflammation.

Conclusions:

• The EP2 receptor is critical for the positive feedback regulation of intestinal COX-2 by PGE2 during inflammation.
• Targeting the EP2 receptor represents a potential novel therapeutic strategy for managing necrotizing enterocolitis and other intestinal inflammatory conditions.