Page 179 - Veterinary Immunology, 10th Edition

VetBooks.ir Resolution of Inflammation

It was once thought that inflammation simply went away when its
cause, such as infection, was removed. This is not the case. The

resolution of inflammation is an active process. Once invading
organisms have been destroyed, affected tissues must switch from a
killing process to a repair process. Proresolving molecules are
produced that counteract the proinflammatory processes. For
example, as inflammation progresses, macrophages change their

polarization (Fig. 6.14). The first macrophages that enter the site are
activated in the classical manner by TNF-α and GM-CSF to kill
invading bacteria. However, these M1 macrophages gradually

convert to M2 cells and develop antiinflammatory properties as
they receive different signals from the tissues. Thus the same cell
can act in a proinflammatory manner at the beginning of an
infection but switch to antiinflammatory activities once the
infection is overcome and it receives different signals.

FIG. 6.14 The role of M2 macrophages in tissue breakdown and
tissue repair in wound healing. In effect, damaged tissues must be
removed before repair and remodeling can begin.

Inflammation is also resolved by an active coordinated process
mediated by a complex mixture of lipids related to the leukotrienes.

These include resolvins, protectins, maresins, and lipoxins.

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