Effect of interleukin-6 deficiency on the formation of periapical lesions after pulp exposure in mice

Objective. The multifunctional cytokine interleukin-6 (IL-6) has actions on multiple cell types, including promotion of the development of immune cell s and osteoclasts. Periapical inflammation as the result of root canal infe ction is characterized by the accumulation of inflammatory cells and bone r esorption. The effect of IL-6 on periapical lesion formation after pulpal i nfection is unknown. We sought to determine whether deletion of IL-6 affect s periapical lesion formation after pulp exposure. Methods. Molar pulps of homozygous IL-6 knock-out mice (IL-6(-/-), strain B 6, 129-ll6tm1koe) and wild-type mice (IL-6(+/+)) were exposed, and the mice were killed at 1, 2, 3, 5, and 8 weeks after the exposure. Mouse jaws were decalcified and prepared for histologic examination of periapical lesions. Results. The IL-6(-/-) mice developed larger periapical lesions more rapidl y than did the IL-6(+/+) mice. Conclusions. IL-6 deletion promoted periapical lesion development.