Immunohistochemical localization of oncostatin M in epithelialized apical periodontitis lesions

Periradicular tissue fluid-derived biomarkers for apical periodontitis: An in vitro methodological and in vivo cross-sectional study

BACKGROUND

Periradicular tissue fluid (PTF) offers a source of diagnostic, prognostic and predictive biomarkers for endodontic disease.

AIMS

(1) To optimize basic parameters for PTF paper point sampling in vitro for subsequent in vivo application. (2) To compare proteomes of PTF from teeth with normal apical tissues (NAT) and asymptomatic apical periodontitis (AAP) using high-throughput panels.

METHODOLOGY

(1) To assess volume absorbance, paper points (n = 20) of multiple brands, sizes and sampling durations were inserted into PBS/1%BSA at several depths. Wetted lengths (mm) were measured against standard curves to determine volume absorbance (μL). To assess analyte recovery, paper points (n = 6) loaded with 2 μL recombinant IL-1β (15.6 ng/mL) were eluted into 250 μL: (i) PBS; (ii) PBS/1% BSA; (iii) PBS/0.1% Tween20; (iv) PBS/0.25 M NaCl. These then underwent: (i) vortexing; (ii) vortexing/centrifugation; (iii) centrifugation; (iv) incubation/vortexing/centrifugation. Sandwich-ELISAs determined analyte recovery (%) against positive controls. (2) Using optimized protocols, PTF was retrieved from permanent teeth with NAT or AAP after accessing root canals. Samples, normalized to total fluid volume (TFV), were analysed to determine proteomic profiles (pg/TFV) of NAT and AAP via O-link Target-48 panel. Correlations between AAP and diagnostic accuracy were explored using principal-component analysis (PCA) and area under receive-operating-characteristic curves (AUC [95% CI]), respectively. Statistical comparisons were made using Mann-Whitney U, anova and post hoc Bonferonni tests (α < .01).

RESULTS

(1) UnoDent's 'Classic' points facilitated maximum volume absorbance (p < .05), with no significant differences after 60 s (1.6 μL [1.30-1.73]), 1 mm depth and up to 40/0.02 (2.2 μL [1.98-2.20]). For elution, vortexing (89.3%) and PBS/1% BSA (86.9%) yielded the largest IL-1β recovery (p < .05). (2) 41 (NAT: 13; AAP: 31) PTF samples proceeded to analysis. The panel detected 18 analytes (CCL-2, -3, -4; CSF-1; CXCL-8, -9; HGF; IL-1β, -6, -17A, -18; MMP-1, -12; OLR-1; OSM; TNFSF-10, -12; VEGF-A) in ≥75% of AAP samples at statistically higher concentrations (p < .01). CXCL-8, IL-1β, OLR-1, OSM and TNFSF-12 were strongly correlated to AAP. 'Excellent' diagnostic performance was observed for TNFSF-12 (AUC: 0.94 [95% CI: 0.86-1.00]) and the PCA-derived cluster (AUC: 0.96 [95% CI: 0.89-1.00]).

CONCLUSIONS

Optimized PTF sampling parameters were identified in this study. When applied clinically, high-throughput proteomic analyses revealed complex interconnected networks of potential biomarkers. TNFSF-12 discriminated periradicular disease from health the greatest; however, clustering analytes further improved diagnostic accuracy. Additional independent investigations are required to validate these findings.

Adipokines in dental pulp: physiological, pathological, and potential therapeutic roles

BACKGROUND

Hundreds of adipokines have been identified, and their extensive range of endocrine functions-regulating distant organs such as oral tissues-and local autocrine/paracrine roles have been studied. In dentistry, however, adipokines are poorly known proteins in the dental pulp; few of them have been studied despite their large number. This study reviews recent advances in the investigation of dental-pulp adipokines, with an emphasis on their roles in inflammatory processes and their potential therapeutic applications.

HIGHLIGHTS

The most recently identified adipokines in dental pulp include leptin, adiponectin, resistin, ghrelin, oncostatin, chemerin, and visfatin. They have numerous physiological and pathological functions in the pulp tissue: they are closely related to pulp inflammatory mechanisms and actively participate in cell differentiation, mineralization, angiogenesis, and immune-system modulation.

CONCLUSION

Adipokines have potential clinical applications in regenerative endodontics and as biomarkers or targets for the pharmacological management of inflammatory and degenerative processes in dental pulp. A promising direction for the development of new therapies may be the use of agonists/antagonists to modulate the expression of the most studied adipokines.

GP130 cytokines and bone remodelling in health and disease

Cytokines that bind to and signal through the gp130 co-receptor subunit include interleukin (IL)-6, IL-11, oncostatin M (OSM), leukemia inhibitory factor (LIF), cardiotrophin-1 (CT-1), and ciliary neutrophic factor (CNTF). Apart from contributing to inflammation, gp130 signalling cytokines also function in the maintenance of bone homeostasis. Expression of each of these cytokines and their ligand-specific receptors is observed in bone and joint cells, and bone-active hormones and inflammatory cytokines regulate their expression. gp130 signalling cytokines have been shown to regulate the differentiation and activity of osteoblasts, osteoclasts and chondrocytes. Furthermore, cytokine and receptor specific gene-knockout mouse models have identified distinct roles for each of these cytokines in regulating bone resorption, bone formation and bone growth. This review will discuss the current models of paracrine and endocrine actions of gp130-signalling cytokines in bone remodelling and growth, as well as their impact in pathologic bone remodelling evident in periodontal disease, rheumatoid arthritis, spondylarthropathies and osteoarthritis.

The upregulation of oncostatin M in inflamed human dental pulps

AIM

To compare oncostatin M (OSM) expression in clinically healthy and inflamed specimened human pulp tissue.

METHODOLOGY

Thirty pulpal tissue specimens (15 clinically healthy and 15 inflamed) were obtained from extracted third molars with informed consent from patients. The levels of OSM were compared between clinically healthy pulp and inflamed pulp tissues using the semi-quantitative reverse-transcriptase polymerase chain reaction. In addition, immunohistochemistry was used to identify the in situ localization of OSM expression in pulp specimens. For testing of differences in the OSM between the clinically healthy and inflamed human dental pulps, the Wilcoxon-Mann-Whitney rank sum test was applied. Differences in OSM expression between tissue with low and high levels of inflammation were subsequently analysed by Fisher's exact test.

RESULTS

Inflamed pulps exhibited significantly higher OSM mRNA gene expression than clinically healthy pulps (P < 0.05). Immunohistochemistry demonstrated that OSM expression was significantly higher in inflamed than clinically healthy pulps (P < 0.05). OSM staining was detected in odontoblasts, fibroblasts, inflammatory infiltrates and endothelial cells.

CONCLUSIONS

Oncostatin M expression was elevated in inflamed pulp tissue. OSM is potentially involved in the disease process of pulpal inflammation.