Local Zoledronate Administration Modulates Periapical Lesion Development in Immunologically Distinct Rat Strains

Area of Science:

• Immunology
• Oral Biology
• Pharmacology

Background:

• Periapical lesions involve complex inflammatory and bone remodeling processes.
• Host immune phenotype significantly influences disease progression and treatment response.
• Understanding these interactions is crucial for developing targeted therapies.

Purpose of the Study:

• To investigate the impact of local zoledronate on periapical lesions in Dark Agouti (DA) and Albino Oxford (AO) rats.
• To compare inflammatory and bone remodeling responses in two distinct immune profiles (Th1-dominant DA vs. Th2-dominant AO).
• To assess the influence of host immunity on zoledronate's therapeutic effects.

Main Methods:

• Periapical lesions were induced in rat molars.
• Local zoledronate or saline was administered over 21 days.
• Lesion size was assessed via radiography and histology.
• Osteogenic activity (osteocalcin), gene expression (cytokines, RANKL/OPG), and oxidative stress were analyzed.

Main Results:

• Zoledronate reduced lesion size and increased bone density in AO rats compared to DA rats.
• AO rats showed higher osteocalcin expression, indicating enhanced osteogenesis.
• DA rats exhibited higher pro-inflammatory cytokines (TNF-α, IL-1β), while AO rats showed higher anti-inflammatory cytokines (IL-10, IL-4).
• Zoledronate decreased RANKL expression in AO rats, suggesting reduced osteoclastogenesis.

Conclusions:

• Local zoledronate treatment modulates periapical lesion development differently based on host immune phenotype.
• Th2-dominant AO rats demonstrated reduced inflammation and increased bone formation.
• Th1-dominant DA rats showed attenuated osteoclast signaling but limited osteogenic response.
• Immune status is a critical factor determining the efficacy of local zoledronate therapy.