Probiotic-based irrigation solution reduces neutrophil extracellular trap formation and stimulates CRAMP antimicrobial peptide expression in rat teeth with induced periapical lesions.

OBJECTIVE: To evaluate the effect of the probiotic Bifidobacterium animalis subsp. lactis (B. lactis) HN019, as an irrigation solution, on the expression of neutrophil extracellular traps (NETs) and the antimicrobial peptide CRAMP, in rats with induced periapical lesions. METHODOLOGY: Periapical lesions were induced in the first molars of forty-five Wistar Hannover rats, with an experimental period of 21 days. The animals were divided into groups based on the irrigating solution and the number of sessions. Semiquantitative analysis was performed using HE staining, neutrophil counts, and histomorphometric analysis of the periapical lesions. Additionally, immunohistochemistry for CRAMP and immunofluorescence for NETs markers such as H3Cit, MPO, and NE were conducted. qRT-PCR analysis was performed for CAMP, ELANE, MPO, and H3F3B. RESULTS: The probiotic irrigation groups showed better results for periodontal ligament parameters (p = 0.03) and inflammatory infiltrate (p = 0.004). A single probiotic irrigation resulted in the highest absence of cementum and bone resorption (85.71% and 71.43%). The periapical lesion area was smaller (p = 0.002), and neutrophil counts showed no difference (p = 0.064). Lower immunolabeling for H3Cit (p = 0.002), MPO (p < 0.001), and NE (p = 0.001) was observed in probiotic-irrigated groups, with reduced gene expression of CAMP (p < 0.001), MPO (p = 0.002), and ELANE (p = 0.001). CONCLUSION: The probiotic-based irrigation solution was effective in reducing neutrophil extracellular trap formation. Additionally, the probiotic solution stimulated CRAMP expression and had a positive effect in preventing cementum and bone resorption. CLINICAL RELEVANCE: The results demonstrate the potential application of the probiotic-based irrigation solution as a promising therapeutic approach for the treatment of periapical lesions.