Involvement of CCR5 in bone resorption associated to apical periodontitis

Abstract

Abstract The involvement of Cysteine-cysteine chemokine receptor 5 (CCR5) in the protection or stimulation of bone resorption associated with apical periodontitis that occur as consequence of endodontic infection has not yet been elucidated. The present study proposes to characterize the involvement of CCR5 in the genesis and progression of apical periodontitis, using animals deficient for this molecule. Experimental induction of periapical lesions was performed in CCR5 −/− (knockout) or wild type transgenic mice through the coronary opening of the lower 1st molars and exposure of the root canals to the oral environment for their contamination. After the death of the animals (at 0, 7, 21 and 42 days), the samples obtained in different experimental periods were evaluated by conventional microscopy and fluorescence (morphometry and characterization of the lesions), histoenzimology (TRAP for osteoclasts), immunohistochemistry, immunofluorescence and real-time PCR, to characterize the inflammatory cell in the presence or absence of CCR5 (neutrophils, macrophages and CD4 and CD8 lymphocytes), expression of cytokines (IL-1±, TNF-±, IFN-³, IL 4, IL-6 and IL-10), their ligands (RANTES and MIP- 1±) and factors involved in bone formation and resorption (RUNX2, NFATc1, ALP, RANK, RANKL, OPG and cathepsin K) and infection of tissues. Our results shows that CCR5 knockout mice developed more extense and severe inflammation and alveolar bone destruction at periapical region at 21 and 42 days after endodontic infection. It was concluded that CCR5 deficiency results in development of more severe periapical alveolar bone resorption associated to endodontic infection.