Immunomodulation Mediated by Azithromycin in Experimental Periapical Inflammation.

Area of Science:

• Endodontics
• Immunology
• Pharmacology

Background:

• Periapical lesions involve complex host-pathogen interactions.
• Antibiotic selection for endodontic treatment requires understanding immunomodulatory effects.

Purpose of the Study:

• To compare the in vitro immunomodulatory effects of azithromycin (AZM), ampicillin (AMP), amoxicillin (AMX), and clindamycin (CLI).
• To evaluate the in vivo effect of AZM on preexisting periapical lesions compared to AMP.

Main Methods:

• Agar disk diffusion assay for antimicrobial susceptibility.
• In vivo study using C57BL/6J mice with periapical lesions treated with AZM, AMP, or PBS.
• Micro-computed tomography and histology for bone healing and inflammatory cell infiltration.
• In vitro assessment of antibiotic effects on pathogen-stimulated NF-κB activation and cytokine production.

Main Results:

• All tested pathogens were susceptible to the antibiotics.
• AZM significantly reduced periapical bone loss and promoted localized neutrophil and M2 macrophage infiltration with fibrosis.
• AMP showed milder inflammatory cell infiltration with a predominance of M1 macrophages.
• AZM suppressed NF-κB activation and cytokine production, while other antibiotics had moderate effects on cytokine production only.

Conclusions:

• Azithromycin (AZM) effectively resolved experimental periapical inflammation and promoted advanced wound healing.
• AZM's immunomodulatory effect appears superior to AMP in managing periapical lesions.
• Clinical trials are warranted to confirm AZM's benefits as adjunctive endodontic therapy.