In Vivo Evaluation of NLRP3 Inflammasome and IL-1β Cytokine in Periapical Lesion Progression Using Wild-Type and TLR2 Knockout Mice.

Abstract

This study aimed to investigate the role of Toll-like receptor 2 (TLR2) in the progression of periapical lesions by evaluating NLRP3 inflammasome and interleukin-1 beta (IL-1β) expression in wild-type (WT) and TLR2 knockout (KO) mice. A total of 55 mice (28 WT, 27 TLR2-KO) underwent pulpal exposure of mandibular first molars and were euthanised at 7, 21, or 42 days post-exposure. Histological and immunohistochemical analyses were performed. TLR2-KO mice showed significantly larger periapical lesions and higher IL-1β expression than WT mice after 21 and 42 days, respectively. In contrast, NLRP3 expression was significantly greater in WT mice at both time points. A weak but significant positive correlation between NLRP3 and IL-1β expression was observed only in WT mice. These findings suggest that TLR2 plays a protective role in limiting periapical bone resorption and modulating inflammatory cytokine expression, independent of NLRP3 inflammasome activity.