Effect of bacterial chemotactic peptides on intestinal inflammation in animal models of acute and chronic "relapsed" colitis.

It is known that bacterial chemotactic peptides such as formyl-methionyl-leucyl-phenylalanine (fMLP) exacerbate colitis during the acute phase, but the precise role of fMLP during chronic "relapse" is unknown. In this study we examined the effect of bacterial peptides in animal models of acute and chronic "relapsed" colitis. Different parameters were evaluated, such as tissue damage, myeloperoxidase activity, and mucosal function. In acute trinitrobenezene sulfonic acid colitis, fMLP had significant adverse effects on mucosal function and worsened several parameters. In contrast, in chronic "relapsed" colitis the ability of fMLP to exacerbate the inflammation was dependent on whether it was confined to the lumen of the colon. Bacterial peptides such as fMLP appear to play a different role in the acute phase of inflammation compared with the chronic phase, depending on the integrity of the mucosal barrier.