Periodontal Fibroblasts-Macrophage Crosstalk in External Inflammatory Root Resorption.

INTRODUCTION: This study aimed to understand the influence of periodontal fibroblasts (PDLFs) on clastic differentiation of macrophages (Mphi) in different resorptive environments. METHODS: PDLF-Mphi direct coculture (juxtacrine) was seeded on dentin, cementum, and polystyrene with/without lipopolysaccharide, macrophage colony-stimulating factor, and receptor activator of nuclear factor kappa beta ligand for 7 and 14 days and stained for tartrate-resistant acid phosphatase (TRAP) activity. PDLF-Mphi cocultured on polystyrene were immunostained for CD80, CD206, NFATc1, STAT6, and periostin, and cell culture supernatants were assessed for cytokines on days 2 and 7. Mphi grown in conditioned media of PDLFs (paracrine) and Mphi monoculture were used as controls. Data was analyzed using Student t test and one-way analysis of variance with the Tukey multiple comparisons test (P < .05). RESULTS: PDLF-Mphi coculture showed a higher number of TRAP-positive multinucleated cells than Mphi monoculture on dentin and polystyrene. No TRAP-positive multinucleated cells were observed in paracrine and cementum. The expression of CD80 and CD206 in PDLF-Mphi was similar at day 2, whereas CD206 was greater than CD80 at day 7. The expression of STAT6 was greater than NFATc1 at both days 2 and 7 (P < .05). Periostin expression in the presence of the lipopolysaccharide, macrophage colony-stimulating factor, and receptor activator of nuclear factor kappa beta ligand combination was down-regulated in PDLF monoculture, whereas it was up-regulated in PDLF-Mphi coculture. The cytokine profile of PDLF-Mphi on day 2 was predominated by interleukin (IL)-1beta, tumor necrosis factor alpha, and MMP9 and MMP2 on day 7. IL-6 and IL-8 showed steady expression at both days 2 and 7. CONCLUSIONS: The study highlights the juxtacrine effect of PDLFs on the clastic differentiation of Mphi with a difference in clastic activity between dentin and cementum. The study also emphasizes the temporal effect of tumor necrosis factor alpha, MMP2, MMP9, and IL-1beta on intercellular crosstalk in resorptive environments.