Interleukin-17 is involved in orthodontically induced inflammatory root resorption in dental pulp cells

Association of genetic polymorphism of interleukin 1-alpha and interleukin 1-beta with external apical root resorption in orthodontic patients

OBJECTIVE

To assess the allele rs 1143634 in IL-1β and rs1800587 in IL-1α in patients for orthodontically induced external apical root resorption (EARR).

MATERIAL AND METHODS

Intra-oral periapical radiograph (IOPA) of maxillary incisors of 142 Patients were evaluated for resorption at two time points; before the start of fixed mechanotherapy (T1) and after one year of treatment (T2). The individuals with root resorption<2mm were categorized as a control group (group 1; n=90), and resorption>2mm were categorized as case group (group 2; n=52). Buccal swabs of all patients were taken and DNA could be isolated in 95 out of 142 samples (group 1 {n=58}, group 2 {n=37}), which were then screened for the selected two polymorphic targets to determine the nucleotide status of these targets. Tetra-primer ARMS PCR reactions were carried out using all 4 primers for each polymorphism.

RESULTS

rs11800587 was not associated with risk of EARR in any inheritance model. Chi-square test for association of alleles with EARR revealed that rs1143634 was associated with the risk of EARR in an allelic model in such a way that A allele of this SNP increased the risk of EARR 4 folds [OR=4.375; P=0.016]. However, the adjusted level of significance using the Holm-Bonferroni method for rs1143634 was P<0.010 for A and G comparison rendering the results non-significant.

CONCLUSION

SNP rs1143634 and SNP rs11800587 were not associated with risk of EARR in any inheritance model.

Periodontal ligament cells-derived exosomes promote osteoclast differentiation via modulating macrophage polarization

Several studies have demonstrated that exosomes (Exos) are involved in the regulation of macrophage polarization and osteoclast differentiation. However, the characteristics as well as roles of exosomes from human periodontal ligament cells (hPDLCs-Exos) in M1/M2 macrophage polarization and osteoclast differentiation remain unclear. Here, periodontal ligament cells were successfully extracted by method of improved Type-I collagen enzyme digestion. hPDLCs-Exos were extracted by ultracentrifugation. hPDLCs-Exos were identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blotting (WB). Osteoclast differentiation was evaluated by real-time quantitative polymerase chain reaction (RT-qPCR), WB and tartrate-resistant acid phosphatase (TRAP) staining. M1/M2 macrophage polarization were evaluated by RT-qPCR and WB. The results showed hPDLCs-Exos promoted osteoclast differentiation and M2 macrophage polarization, but inhibited M1 macrophage polarization. Moreover, M1 macrophages inhibited osteoclast differentiation, whereas M2 macrophages promoted osteoclast differentiation. It has shown that hPDLCs-Exos promoted osteoclast differentiation by inhibiting M1 and promoting M2 macrophage polarization.

External apical root resorption in orthodontic patients: molecular and genetic basis

External apical root resorption is one of the most deleterious complications after orthodontic treatment. Studies to explain the causal relationship between orthodontic tooth movement and external apical root resorption have been inconclusive till date. Individual variations in external apical root resorption sometimes overshadow the treatment related factors which indicate genetic predisposition and/or multifactorial etiology. Mechanism of root resorption is not completely understood. Inflammatory root resorption induced by orthodontic treatment is a part of process of elimination of hyaline zone. An imbalance between bone resorption and deposition may contribute to root resorption by the cementoclasts/osteoclasts. This narrative review article explains the molecular pathway involved in external apical root resorption and also role of various genes involved at different level. It also reviews the literature published during the past 20 years concerning the association studies linking EARR to genetic polymorphisms. This literature review provides an insight into genetic predisposition of external apical root resorption that can be used in orthodontic practice to enable 'high-risk' subjects to be identified on the basis of their genetic information before orthodontic treatment is initiated.

Involvement of interleukins-17 and -34 in exacerbated orthodontic root resorption by jiggling force during rat experimental tooth movement

BACKGROUND

Orthodontically induced root resorption (OIRR) is considered as an undesirable and unpredictable sequel of orthodontic treatment. Recent reports demonstrated that interleukin (IL)-17/IL-34, and T cells secrete inflammatory/osteoclastogenic cytokines, which might stimulate osteoclastogenesis/bone resorption. However, little is known about the role played by IL-17/IL-34 in OIRR. The present study was aimed at investigating the odontoclastic expression pattern of IL-17 and IL-34 in resorbed cementum during different experimental tooth movements in vivo.

METHODS

Twenty-four 8-week-old male Wistar rats were divided into four groups: control group, optimal force group (10 g), heavy force group (50 g), and jiggling force group (compression and tension, repetition; 10 g). After 7, 14, and 21 days, the expression levels of IL-17 and IL-34 protein in the resorbed cementum were analyzed using immunohistochemical methods.

RESULTS

On day 21, the immunoreactivity for IL-17 and IL-34 in resorbed roots in the jiggling force group was stronger than that in the heavy force and optimal force groups. Moreover, the number of IL-17-positive and IL-34-positive odontoclasts was significantly increased in the jiggling force group compared with those in the other groups on day 21.

CONCLUSIONS

These results suggest that jiggling forces might exacerbate OIRR compared with heavy forces, as evidenced by the increased expression of IL-17 and IL-34 in odontoclasts obtained from resorbed roots.

Clinical and histopathological characterization of root resorption in replanted teeth: Two case reports

RATIONALE

The frequency of tooth avulsion is on the rise due to increasing rates of maxillofacial trauma. Avulsed teeth present with varying degrees of root resorption, and are generally asymptomatic; therefore, they often go undiagnosed. The etiopathogenesis of root resorption in replanted teeth following avulsion remains unclear.

PATIENT CONCERNS

In case 1, the left upper lateral incisor became loose after 10 years of replantation. In case 2, the patient underwent tooth replantation after external root canal treatment due to tooth dislocation caused by trauma 8 years ago.

DIAGNOSIS

According to the medical history, clinical manifestations and imaging studies of the 2 patients, root resorption after replantation was diagnosed.

INTERVENTIONS

The teeth extraction was given to one patient. Besides the histological examination of extracted teeth was performed.

OUTCOMES

Teeth that underwent pulp treatment presented with external resorption. On the other hand, the tooth that had received no pulp treatment showed both external and internal resorption; residual vital pulp tissue was detected within the pulp cavity.

LESSONS

The dental pulp tissues may be involved in the initiation or development of internal resorption. Trauma to the periodontal ligament might play a major role in external resorption, whereas internal tooth resorption may be caused as a result of injury to the residual pulp tissue. Thus, the effective management of these tissues during the treatment of replanted teeth is essential.

The Presence and involvement of interleukin-17 in apical periodontitis

Apical periodontitis (AP) is a chronic inflammatory disease characterized by periapical tissue inflammation and destruction of the associated alveolar bone. It is caused by microbial infections within the root canal and the resultant host immune responses in the periapical tissues. The proinflammatory cytokine interleukin (IL)-17 has been shown to play an important role in many inflammatory diseases. There is increasing evidence of the presence of IL-17 in AP, which might be associated with disease pathogenesis. Moreover, several animal studies indicate the potential role of IL-17 in periapical inflammation and the resultant bone resorption in AP. This article reviews recent studies regarding the collective in vitro, in vivo and clinical evidence of the presence and involvement of IL-17 in AP. A search related to IL-17 in apical periodontitis was conducted on PubMed, EMBASE and Web of Science databases using keywords and controlled vocabulary. Two independent reviewers first screened titles and abstracts and then the full texts that were included. A total of 25 papers were identified, of the 25 included articles, 7 involved laboratory studies on cell cultures, 11 involved animal experimentations, and 7 were observational studies using human clinical samples. In conclusion, evidence for the presence of IL-17 in AP from human and animal models is clear. However, there is relatively little information currently available that would highlight the specific role of IL-17 in AP.

Odontoclastogenesis of mouse papilla-derived MDPC-23 cells induced by lipopolysaccharide

AIM

To investigate the role of Lipopolysaccharide (LPS) in the odontoclast differentiation of MDPC-23 cells. It was hypothesized that MDPC-23 odontoblast-like cells may function as odontoclasts under the influence of LPS.

METHODOLOGY

MDPC-23 cells were cultured in the presence of 0.1 or 1 μg mL^-1 LPS for 6 days. Cell viability was determined using the CCK8 assay. TRAP staining, dentine resorption assay and ROS detection by confocal laser scanning microscope were used to test the odontoclast-like function of the induced cells. In additional, the related protein expression was confirmed by Western blotting and ELISA. An unpaired Student's t-test and one-way anova were used in statistical analysis.

RESULTS

TRAP-positive cells, which are multinucleated, on the dentine slice were significantly increased in 1 μg mL^-1 LPS-induced cells (P < 0.05). Osteoclast-specific proteins such as TRAP cathepsin K and Rac1 were upregulated in the 1 μg mL^-1 LPS-treated cells (P < 0.05), whilst the expression of marker proteins of the RANKL-RANK signalling pathway (RANKL, RANK and TRAF6) in the induced cells was not significantly changed (P > 0.05). ROS production was observed in the 1 μg mL^-1 LPS treatment group (P < 0.05), but no significant differences were observed in the level of RANKL in the cell supernatant between the LPS-treated group and the control group (P > 0.05).

CONCLUSIONS

A known value of 1 μg mL^-1 LPS might induce odontoblast-like MDPC-23 cells to generate odontoclast-like cells or to function as odontoclasts. The data might provide a new explanation for the precursors of odontoclasts and root resorption.

Genetic determinants and postorthodontic external apical root resorption in Czech children

OBJECTIVE

Genes, involved in the modulation of inflammatory response and bone remodeling, play a role in the development of postorthodontic external apical root resorption (EARR). The aim of our study was to analyze possible associations between seven single nucleotide polymorphisms (SNPs) in interleukin-17A (IL-17), osteopontin (SPP1), purinoreceptor P2X7 (P2RX7), and tumor necrosis factor receptor superfamily member 11B (TNFRSF11B) genes and EARR in children after orthodontic treatment.

SUBJECTS AND METHODS

This case-control study comprised 99 orthodontically treated patients (69 controls and 30 subjects with EARR). Genotype determinations of rs2275913, rs11730582, rs9138, rs208294, rs1718119, rs3102735, and rs2073618 were based on polymerase chain reaction using 5' nuclease TaqMan^® assays.

RESULTS

While no significant differences were observed in allele or genotype frequencies of all seven studied SNPs, specific haplotype of P2RX7 (rs208294 and rs1718119) modified the risk of EARR development (P < 0.05). In addition, the length of treatment with a fixed orthodontic appliance positively correlated with the presence of EARR (P < 0.05).

CONCLUSIONS

Although the effect of individual SNPs studied on the EARR development was not confirmed in the Czech population, complex analysis suggested that variability in the P2RX7 gene and the length of orthodontic treatment may be important factors contributing to the etiopathogenesis of postorthodontic EARR.