Apolipoprotein A-IV inhibits experimental colitis.

Area of Science:

• Immunology
• Gastroenterology
• Vascular Biology

Background:

• Apolipoprotein A-IV (apoA-IV) possesses antiatherogenic properties, suggesting potential anti-inflammatory roles.
• Acute colitis models are crucial for understanding inflammatory bowel diseases and testing therapeutic interventions.

Purpose of the Study:

• To investigate the anti-inflammatory potential of apoA-IV in a mouse model of dextran sulfate sodium (DSS)-induced acute colitis.
• To elucidate the mechanisms underlying apoA-IV's anti-inflammatory effects, focusing on leukocyte and platelet interactions.

Main Methods:

• Mice were administered DSS in drinking water to induce colitis, with or without apoA-IV treatment.
• Clinical disease activity, colon histology, and myeloperoxidase activity were assessed.
• Intravital fluorescence microscopy examined leukocyte and platelet adhesion in colonic microvasculature.
• P-selectin expression on colonic endothelium was evaluated.
• Experiments included apoA-IV knockout mice and rescue studies with exogenous apoA-IV administration.

Main Results:

• ApoA-IV significantly delayed the onset and reduced the severity and extent of DSS-induced colitis.
• ApoA-IV inhibited leukocyte and platelet adhesive interactions in the colonic microvasculature.
• ApoA-IV markedly reduced P-selectin upregulation on colonic endothelium.
• ApoA-IV knockout mice showed exacerbated DSS-induced inflammation, which was reversed by apoA-IV administration.

Conclusions:

• These findings provide direct evidence that apoA-IV is an endogenous anti-inflammatory protein.
• The anti-inflammatory action of apoA-IV likely involves the inhibition of P-selectin-mediated leukocyte and platelet adhesion.
• ApoA-IV represents a potential therapeutic target for inflammatory conditions like colitis.