Periapical lesion progression and cytokine expression in an LPS hyporesponsive model

Aim The purpose of this study was to compare periapical lesion progression and the expression of the bone modulating cytokines IL-1 alpha, TNF-alpha, IL-4, IL-6 and IL-11 in periapical lesions of normal and C3H/HeJ (LPS hyporesponsive) mice. Methodology Pulps of both mandibular first molars from C3H/HeJ and BALB/c (normal) mice were exposed and inoculated with normal mouse oral microorganisms for 2, 4, 6, and 8 weeks. After euthanasia, specimens were prepared for histological examination. A quantitative evaluation of the lesional area and immunohistochemical stain counts was performed. Results There were no statistically significant differences In progression of periapical lesions for both mouse strains with time (two-factor ANOVA, P > 0.05). The immunohistochemical staining revealed no overall differences between the two strains in levels of expression of the cytokines (P > 0.05). IL-11 expression did not change from control levels In BALB/c mice, but correlated with the expression of IL-6 and IL-4 in C3H/HeJ mice. Conclusion Responsiveness to LPS may not be significant in the pathogenesis of periapical lesions and in cytokine expression within the lesions. when the lesions are induced by non-specific oral flora.