TLRs expression in CD1a+ DCs from inflamed human dental pulps

OBJECTIVE: Dendritic cells (CDs) have been described as the first defense line in human dental pulp (HDP); these cells express TLR2 and TLR4 which could induce inflammatory mediator's synthesis that might influence the development of acute irreversible pulpitis (AIP). The purpose of this study was to determine the expression of TRL2 and TRL4 in CD1a+ CDs and subtypes from HDP with AIP diagnosis. METHODS: 47 HDP samples were obtained from healthy premolars indicated for orthodontic reasons and 12 with AIP diagnosis. The samples were homogenized and stained with MAbs CD1a, anti-CD16, anti-CD68, anti-TLR2 and anti-TLR4 to its identification by flow cytometry. The obtained data were analyzed using SPSS V.14 for Windows. RESULTS: A significant increase of CD1a+ CDs in AIP was identified, and this phenotype showed a highly TLR's expression (p<0.05), even three times highly over than healthy HDP. Likewise, it was demonstrated the presence of immature CDs with phenotypes CD1a+/CD68+, which were most abundant in healthy dental pulp (p <0.05) with low levels of TLR2 and TLR4. Hyper-reactive CDs (CD1a+/CD16+) were identified, this population might be related with inflammatory process in HDP by its significative expression in AIP, showing an important increase of TLR2 and TLR4 (p<0.05), being the TRL2 expression significantly higher than TLR4 in inflamed HDP (p <0.05). CONCLUSIONS: Although some authors report CD1a + dendritic cells as Langerhans cells and they are not present in HDP, this ex-vivo model showed CDs with this phenotype at different stages of maturation depending of the pulp inflammatory condition. The increased TLRs expression in CD1a+/CD16+ phenotype from human dental pulp with AIP, suggest an important contribution of its hyperactivity in the inflammatory process within the dental pulp. KEY WORDS: Dendritic cells; acute irreversible pulpitis; TLR2; TLR4.