IL-1 plays a critical role in oral, put not dermal, wound healing

Wound healing is a well-orchestrated complex process leading to the repair of injured tissues. After injury, proinflammatory cytokines act as importan t modulators of the inflammatory process. IL-1 expression has been regarded as necessary for healing; however, its effects have also been implicated i n delayed wound repair. Currently, there is no consensus or direct evidence that IL-1 activity plays a central role in the healing process. The presen t investigation was undertaken to define the role of IL-1R signaling in the healing outcome of an excisional wound in the palate or scalp of mice that had targeted deletions of the IL-1R type 1 (IL-1R1(-/-)) compared with mat ched wild-type mice. Histomorphometric analysis was undertaken to assess th e degree of healing and the recruitment of polymorphonuclear and mononuclea r phagocytes. After 14 days, wild-type mice exhibited complete closure of i ntraoral wounds, while IL-1R1(-/-) animals had only partial closure (50%). In the IL-1R1(-/-) mice, healing tissues exhibited a persistent inflammator y cell infiltrate, which did not occur in wild-type animals. Treatment with antibiotics significantly diminished the persistent inflammatory infiltrat e and improved healing in the experimental animals. In contrast to oral wou nds, the rate of beating and recruitment of polymorphonuclear cells in scal p wounds was similar in IL-1R1(-/-) and wild-type mice. The present data un derscore the importance of IL-1 in wound healing in a challenging environme nt and identify its principal role in facilitating the healing process by p rotecting an open wound from bacterial insult. In a less challenging enviro nment, the production of new connective tissue and its coverage by migratin g epithelium are minimally affected by the absence of IL-1 activity.