Expression of autophagy‑associated proteins in rat dental irreversible pulpitis

Guanylate-binding protein 5-mediated autophagy can promote the clearance of intracellular F. nucleatum in dental pulp cells during pulpitis

BACKGROUND

IFN-γ is crucial in induction of inducible cell-autonomous immunity, and IFN-γ signaling pathway is activated in pulpitis. Guanylate-binding proteins (GBPs) are a family of IFN-inducible GTPases and could utilize autophagy or pyroptosis to mitigate infection. GBP5 is abundantly expressed in inflamed pulp and human dental pulp cells (HDPCs). Therefore, we hypothesize that GBP5 in HDPCs exerts an immune-regulatory role in defending against bacterium infection.

METHODS

Fusobacterium nucleatum (F. nucleatum) was used to infect HDPCs, and immunoblotting and qRT-PCR were used to detect pyroptosis and autophagy. Pharmacological or genetic approaches were used to enhance or knock down GBP5 expression in HDPCs. Blood agar plate counting and immunoblotting were used to observe bacteria clearance effect and activation of autophagy. Student's t-test and one-way ANOVA were individually used for comparisons between two and multiple groups. Statistical significance was set at P < 0.05.

RESULTS

Following F. nucleatum infection in HDPCs, the autophagy marker LC3B was significantly upregulated while the mRNA and protein expression levels of p62 were increased. IFN-γ priming significantly inhibited the intracellular survival of F. nucleatum and enhanced the autophagic activity of HDPCs. GBP5 overexpression significantly increased the efficiency of HDPCs in clearing intracellular F. nucleatum and activated autophagic flux in HDPCs, while downregulating GBP5 in HDPCs suppressed autophagic flux.

CONCLUSION

IFN-γ-mediated GBP5 overexpression in HDPCs during F. nucleatum infection exerts an anti-microbial function through autophagy activation.

BRF1 promotes the odontogenic differentiation of dental pulp stem cells in pulpitis by inducing autophagy

Objective

While post-transcriptional modifications play a pivotal role in the autophagy regulation, studies on dental pulp disease are limited. This study investigated the effect of BRF1 on autophagy in inflamed pulp tissue and human dental pulp stem cells (hDPSCs).

Methods

Immunohistochemical analysis was used to examine BRF1 expression, autophagy levels, and dentinogenic markers in normal and inflamed pulp. The presence of autophagosomes was observed by transmission electron microscopy. Primary hDPSCs were treated with 1 μg/mL lipopolysaccharide (LPS) for different lengths of time. The expression of BRF1 and autophagy makers was determined by Western blotting. BRF1 knockdown and 3 MA treatment were employed to assess changes in autophagy and dentinogenic differentiation. Double immunofluorescence staining was performed to co-localize BRF1 with LC3B in pulp tissue.

Results

The expressions of BRF1, LC3, DMP1, and DSP were significantly elevated in the inflamed pulp. LPS enhanced the protein production of IL-6, BRF1, LC3, and Beclin-1 from 6 h to 24 h after the treatment. BRF1 knockdown reduced the ratio of LC3-II/LC3-I and the differentiation ability of hDPSCs, while 3 MA inhibited LPS-mediated dentinogenic differentiation. Double-labeling revealed that BRF1 co-localized with LC3B in inflamed pulp.

Conclusion

This study demonstrated that BRF1 promoted autophagy activation and odontogenic differentiation in pulpitis.

Drug sensitivity testing during dental pulp-dentin complex repair: its effect on treatment outcome and prognosis

OBJECTIVE

To assess the efficacy of targeted therapy based on drug sensitivity testing (DST) results in patients with acute pulpitis (AP).

METHODS

A total of 80 cases of AP were included retrospectively and divided into two groups: control (Ctrl) group (conventional drug palliative therapy, n=40) and experimental (Exp) group (DST + non-resistant drugs, n=40). The clinical data and laboratory examination data of patients, including bacterial culture data, drug sensitivity test results, Ca and P contents in dental pulp, visual analogue scale (AVS), treatment satisfaction, and dental pulp incidence, were collected and analyzed.

RESULTS

Prevotella melaninogenica, Fusobacterium nucleatum, and Porphyromonas gingivalis exhibited higher resistance rates (RS) to penicillin and amoxicillin but no resistance to imipenem and metronidazole. The content of Ca and P in the dental pulp of the Exp group patients was significantly higher than that of the Ctrl group (P=0.006). The total response rate (95% vs. 77.5%, P=0.018) and overall patient satisfaction (92.5% vs. 80%, P=0.021) were also significantly higher in the Exp group than in the Ctrl group. Additionally, when the follow-up duration exceeded 1 year, the incidence of dental pulp reactions in the Exp group was significantly lower than that of the Ctrl group (P=0.026).

CONCLUSIONS

These findings suggest that Gram-negative anaerobes are the predominant oral pathogens in patients with AP. Imipenem and metronidazole demonstrate the most effective anti-infective properties against these anaerobes. Utilizing DST to select non-resistant drugs for treatment prior to therapy effectively enhances clinical outcomes for patients with AP.

Establishment and validation of the autophagy-related ceRNA network in irreversible pulpitis

BACKGROUND

The molecular mechanisms underlying the onset and progression of irreversible pulpitis have been studied for decades. Many studies have indicated a potential correlation between autophagy and this disease. Against the background of the competing endogenous RNA (ceRNA) theory, protein-coding RNA functions are linked with long noncoding RNAs (lncRNAs) and microRNAs (miRNAs). This mechanism has been widely studied in various fields but has rarely been reported in the context of irreversible pulpitis. The hub genes selected under this theory may represent the key to the interaction between autophagy and irreversible pulpitis.

RESULTS

Filtering and differential expression analyses of the GSE92681 dataset, which contains data from 7 inflamed and 5 healthy pulp tissue samples, were conducted. The results were intersected with autophagy-related genes (ARGs), and 36 differentially expressed ARGs (DE-ARGs) were identified. Functional enrichment analysis and construction of the protein‒protein interaction (PPI) network of DE-ARGs were performed. Coexpression analysis was conducted between differentially expressed lncRNAs (DElncRNAs) and DE-ARGs, and 151 downregulated and 59 upregulated autophagy-related DElncRNAs (AR-DElncRNAs) were identified. StarBase and multiMiR were then used to predict related microRNAs of AR-DElncRNAs and DE-ARGs, respectively. We established ceRNA networks including 9 hub lncRNAs (HCP5 and AC112496.1 ↑; FENDRR, AC099850.1, ZSWIM8-AS1, DLX6-AS1, LAMTOR5-AS1, TMEM161B-AS1 and AC145207.5 ↓), which were validated by a qRT‒PCR analysis of pulp tissue from patients with irreversible pulpitis.

CONCLUSION

We constructed two networks consisting of 9 hub lncRNAs based on the comprehensive identification of autophagy-related ceRNAs. This study may provide novel insights into the interactive relationship between autophagy and irreversible pulpitis and identifies several lncRNAs that may serve as potential biological markers.

Expression of immunomodulatory and tissue regenerative biomarkers in human dental pulp derived-mesenchymal stem cells treated with curcumin: an in vitro study

BACKGROUND

Human Dental pulp derived-mesenchymal stem cells (hDP-MSCs) have the capability of selfrenewal, multipotency, as well as immunosuppressive properties. They are ideal candidates for regenerating damaged dental tissue and treating inflammation-related diseases. However, methods (such as genetic variation) to improve the immunomodulatory and regenerative efficiency of MSCs in different diseases still need to be developed. Curcumin (CUR) is known for its broad applications in regenerative medicine and the treatment of inflammatory disorders via its anti-inflammatory and anti-oxidant effects. This study was conducted to investigate the effect and underlying mechanisms of CUR on the immunomodulatory and regenerative function of hDP-MSCs and whether treating these cells with CUR can improve therapeutic efficacy.

METHODS AND RESULTS

hDP-MSCs were isolated from dental pulp and then treated with CUR. Cell viability rate was observed in hDP-MSCs after treatment of CUR by MTT assay. Real-time quantitative (RT-PCR) was applied to estimate the expression of immunomodulatory and regenerative genes after treatment of CUR. The RT-PCR results showed that VEGF-A and STAT3 markers were up-regulated while HLA-G5 and VCAM-1 markers were down-regulated by CUR (20 µM) treatment in hDP-MSCs (P < 0.001). Besides, this research indicated that there were no significant changes in the expressions of RelA and DSPP after 48 h (P = 0.33, P = 1).

CONCLUSION

Our findings demonstrate that CUR can enhance the immunomodulatory and regenerative effects of hDP-MSCs and improve their therapeutic efficacy. These findings can give an understanding of the mechanism for improving restorative and immunomodulatory activity in hDP-MSCs by curcumin.

Epigenetic Control of Autophagy Related Genes Transcription in Pulpitis via JMJD3

Autophagy is an intracellular self-cannibalization process delivering cytoplasmic components to lysosomes for digestion. Autophagy has been reported to be involved in pulpitis, but the regulation of autophagy during pulpitis progression is largely unknown. To figure out the epigenetic regulation of autophagy during pulpitis, we screened several groups of histone methyltransferases and demethylases in response to TNFα treatment. It was found JMJD3, a histone demethylase reducing di- and tri-methylation of H3K27, regulated the expression of several key autophagy genes via demethylation of H3K27me3 at the gene promoters. Our study highlighted the epigenetic regulation of autophagy genes during pulpitis, which will potentially provide a novel therapeutic strategy.

Review of Animal Models to Study Pulp Inflammation

Human dental pulp is a highly dynamic tissue equipped with a network of resident immunocompetent cells that play a major role in the defense against pathogens and during tissue injury. Animal studies are mandatory and complementary to in vitro experiments when studying the physiopathology of dental pulp, new diagnostic tools, or innovative therapeutic strategies. This animal approach makes it possible to define a benefit-risk ratio necessary to be subsequently tested in humans. Among the animal kingdom, rodents, rabbits, ferrets, swine, dogs, and non-human primates have been used to model human pulpitis. The diversity of animals found in studies indicate the difficulty of choosing the correct and most efficient model. Each animal model has its own characteristics that may be advantageous or limiting, according to the studied parameters. These elements have to be considered in preclinical studies. This article aims to provide a thorough understanding of the different animal models used to study pulp inflammation. This may help to find the most pertinent or appropriate animal model depending on the hypothesis investigated and the expected results.

Clinical Value and Potential Target of miR-27a-3p in Pulpitis

INTRODUCTION

This study investigated the clinical values of miR-27a-3p for pulpitis patients, and its association with TLR4.

METHODS

Sixty-six patients with pulpitis and 34 cases without pulpitis were recruited; the pulp tissue and serum samples were collected from each participant. Real-time polymerase chain reaction was used for measurement of gene expression levels. The diagnosis values were assessed by the receiver operating characteristic curve. The target gene of miR-27a-3p was confirmed by the luciferase reporter assay.

RESULTS

MiR-27a-3p was downregulated in both serum and pulp tissue of pulpitis patients. MiR-27a-3p could distinguish pulpitis patients from healthy controls and might be a predictor for the development of irreversible pulpitis. A high level of TLR4 was also detected in both peripheral blood monocytes and pulp tissues from pulpitis patients and showed a negative association with the miR-27a-3p level. TLR4 was a direct target gene of miR-27a-3p.

DISCUSSION/CONCLUSION

MiR-27a-3p might be a promising biomarker for the diagnosis of pulpitis and predict the development of irreversible pulpitis. MiR-27a-3p might be involved in the pathogenesis of pulpitis via targeting TLR4.

[Role of autophagy in lipopolysaccharide-induced apoptosis of odontoblasts]

OBJECTIVE

To investigate the role of autophagy in lipopolysaccharide (LPS)-induced apoptosis of murine odontoblasts.

METHODS

Murine odontoblasts (mDPC-23 cells) were treated with 5 μg/mL LPS for 6, 12 and 24 h, and the changes in cell viability was examined using CCK8 kit and cell apoptosis was detected by TUNEL staining. The changes in the protein levels of LC3, Beclin1, Atg5, AKT, p-AKT, mTOR and p-mTOR were detected using Western blotting. The effect of 3-MA treatment for 24 h on LPS-induced apoptosis of mDPC-23 cells was evaluated by detecting the expressions of apoptosis-related proteins caspase-3 and Bax using Western blotting.

RESULTS

Stimulation with LPS for 6 and 12 h did not cause significant changes in the proliferation or apoptosis of mDPC-23 cells, but LPS treatment for 24 h significantly suppressed cell proliferation (P < 0.05) and promoted cell apoptosis as shown by TUNEL assay (P < 0.05). Stimulation with LPS for 24 significantly increased the expression levels of LC3, Beclin1 and Atg5, decreased the expressions of p-AKT and p-mTOR (P < 0.05), and obviously upregulated the expressions of caspase-3 and Bax (P < 0.05). Treatment with 3-MA markedly lowered caspase-3 and Bax protein expressions in LPS-stimulated cells (P < 0.05).

CONCLUSIONS

LPS stimulation induces autophagy to promote apoptosis of mDPC-23 cells, and suppression of autophagy attenuates LPS-induced apoptosis. Autophagy may play an important role in the injury of inflamed pulp tissues.