Increased interleukin 1α and interleukin 1β expression is involved in the progression of periapical lesions in primary teeth.

Background: Interleukin 1 (IL-1) is involved in bone resorption. However, the role of IL-1 in periapical lesions characterized by periapical bone destruction in primary teeth has not yet been fully elucidated. This study aimed to detect the distribution and expression of IL-1 in periapical lesions in primary teeth and assess the relationship between the cytokines and the degree of inflammatory cell infiltration.

Methods: A total of 106 chronic periapical lesions in primary teeth were harvested. Haematoxylin and eosin (H&E) staining was used to determine the histological type and the inflammatory cell infiltration grade (mild, moderate, and severe), and immunohistochemistry and enzyme-linked immunosorbent assay (ELISA) were used to detect the distribution and expression of IL-1α and IL-1β.

Results: Of the 106 chronic periapical lesion samples, there were 85 cases of periapical granuloma, accounting for 80.19% of the total samples, and 21 cases of radicular cysts, accounting for 19.81%; no cases of abscess were detected. Immunohistochemistry results showed that both IL-1α and IL-1β were expressed in periapical granulomas and cysts. ELISA results showed that IL-1α and IL-1β levels were higher in the periapical granuloma group than in the radicular cyst and normal control groups (P < 0.05). In the periapical granuloma group, IL-1α and IL-1β were detected at higher levels in the severe inflammatory cell infiltration subgroup than in the mild-inflammatory cell infiltration subgroup (P < 0.05), and IL-1β expression was also higher in the moderate inflammatory cell infiltration subgroup than in the mild inflammatory cell infiltration subgroup (P < 0.01). A significant positive correlation was observed between the protein expression levels of IL-1α and IL-1β and the inflammation grade in periapical granulomas from primary teeth (P < 0.05).

Conclusion: Expression levels of the cytokines IL-1α and IL-1β in periapical granulomas from primary teeth increased with increasing inflammatory severity and appeared to be a contributing factor to the progression of periapical lesions.