Inflamed Pulp Tissue Research Articles

Investigation of Apoptosis in Healthy and Inflamed Pulp Tissue

Investigation of Apoptosis in Healthy and Inflamed Pulp Tissue

A carbon dot nanozyme hydrogel enhances pulp regeneration activity by regulating oxidative stress in dental pulpitis

Preserving pulp viability and promoting pulp regeneration in pulpitis have attracted widespread attention. Restricted by the oxidative stress microenvironment of dental pulpitis, excessive reactive oxygen and nitrogen species (RONS) trigger uncontrolled inflammation and exacerbate pulp tissue destruction. However, modulating redox homeostasis in inflamed pulp tissue to promote pulp regeneration remains a great challenge. Herein, this work proposes an effective antioxidative system (C-NZ/GelMA) consisting of carbon dot nanozymes (C-NZ) with gelatin methacryloyl (GelMA) to modulate the pulpitis microenvironment for dental pulp regeneration by utilizing the antioxidant properties of C-NZ and the mechanical support of an injectable GelMA hydrogel. This system effectively scavenges RONS to normalize intracellular redox homeostasis, relieving oxidative stress damage. Impressively, it can dramatically enhance the polarization of regenerative M2 macrophages. This study revealed that the C-NZ/GelMA hydrogel promoted pulp regeneration and dentin repair through its outstanding antioxidant, antiapoptotic, and anti-inflammatory effects, suggesting that the C-NZ/GelMA hydrogel is highly valuable for pulpitis treatment.

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

ObjectiveWhile 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). MethodsImmunohistochemical 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. ResultsThe 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. ConclusionThis study demonstrated that BRF1 promoted autophagy activation and odontogenic differentiation in pulpitis.

Immune System of Dental Pulp in Inflamed and Normal Tissue.

Teeth are vulnerable to structural compromise, primarily attributed to carious lesions, in which microorganisms originating from the oral cavity deteriorate the mineralized structures of enamel and dentin, subsequently infiltrating the underlying soft connective tissue, known as the dental pulp. Nonetheless, dental pulp possesses the necessary capabilities to detect and defend against bacteria and their by-products, using a variety of intricate defense mechanisms. The pulp houses specialized cells known as odontoblasts, which encounter harmful substances produced by oral bacteria. These cells identify pathogens at an early stage and commence the immune system response. As bacteria approach the pulp, various cell types within the pulp, such as different immune cells, stem cells, fibroblasts, as well as neuronal and vascular networks, contribute a range of defense mechanisms. Therefore, the immune system is present in the healthy pulp to restrain the initial spread of pathogens, and then in the inflamed pulp, it prepares the conditions for necrosis or regeneration, so inflammatory response mechanisms play a critical role in maintaining tissue homeostasis. This review aims to consolidate the existing literature on the immune system in dental pulp, encompassing current knowledge on this topic that explains the diverse mechanisms of recognition and defense against pathogens exhibited by dental pulp cells, elucidates the mechanisms of innate and adaptive immunity in inflamed pulp, and highlights the difference between inflamed and normal pulp tissue.

The profile of cytokines against bacterial infection in dental pulp.

Dental pulp in a confined environment, with little connection to the outside and only a small distribution of immune cells, provides a good research model for investigating how cells respond to bacterial infections through cytokines. The data of single-cell transcriptome sequencing of healthy and inflamed pulp tissue were downloaded from the GEO dataset. The expression character of 79 cytokines was analyzed based on the expression matrix. The cytokine secretion profiles of the two populations of pulp cells in healthy dental pulp were associated with vascularization and nervous system development, as well as immune cell regulation. For the three populations of pulp stem cells with stem cell activity in the dental pulp, the secretion of cytokines related to nervous system development, regulation of endothelial cell proliferation and migration, and regulation of immune cell function comprised the characteristics that we observed. The cytokines secreted by T cells and macrophages were more of an immune reserve against pathogenic microorganisms. In the inflammatory state, the spectrum of cytokines secreted by various types of cells in the dental pulp tended to be identical, such that it mainly resisted pathogenic microorganisms. The cytokine secretion profiles of various cell types in healthy and inflamed dental pulp at the single-cell level are summarized.

Expression patterns of mechanosensitive ion channel PIEZOs in irreversible pulpitis.

Mechanosensitive ion channel PIEZOs have been widely reported to involve inflammation and pain. This study aimed to clarify expression patterns of PIEZOs and their potential relations to irreversible pulpitis. Normal pulp tissues (n = 29) from patients with impacted third molars and inflamed pulp tissues (n = 23) from patients with irreversible pulpitis were collected. Pain levels were assessed using a numerical rating scale. PIEZO expressions were measured using real-time PCR and then confirmed using GEO datasets GSE77459, immunoblot, and immunohistochemistry staining. Correlations of PIEZO mRNA expression with inflammatory markers, pain markers, or clinical pain levels were evaluated using Spearman's correlation analysis. Univariate analysis was conducted to analyze PIEZO expressions based on pain description and clinical examinations of cold test, percussion, palpation, and bite test. Compared with normal pulp tissues, mRNA expression levels of PIEZO1 were significantly increased in inflamed pulp tissues, while PIEZO2 was significantly decreased, which was further confirmed in GSE77459 and on a protein and histological level. The positive correlation of the mRNA expression levels between PIEZO1 and inflammatory markers, as well as between PIEZO2 and pain markers, was verified. PIEZO2 expression was also positively correlated with pain levels. Besides, irreversible pulpitis patients who reported continuous pain and who detected a positive response to cold stimulus exhibited a higher expression level of PIEZO2 in the inflamed pulp tissues. By contrast, patients reporting pain duration of more than one week showed a higher expression level of PIEZO1. This study demonstrated the upregulation of PIEZO1 and the downregulation of PIEZO2 in irreversible pulpitis and revealed the potential relation of PIEZO1 and PIEZO2 to inflammation and pain. These findings suggested that PIEZOs might play critical roles in the progression of irreversible pulpitis and paved the way for further investigations aimed at novel therapies of irreversible pulpitis by targeting PIEZOs.

Evaluation of Antimicrobial Efficacy of Etidronic Acid against Enterococcus faecalis in Primary Teeth: An In Vivo Study.

In pulpectomy, to remove the inflamed or diseased pulp tissues and smear layer, the root canal is disinfected with mechanical instrumentation and copious irrigation. The purpose of this present study is to evaluate the antibacterial efficacy of etidronic acid as an irrigant in primary teeth. A total of 60 necrotic primary teeth in children aged 3-8 years were included. Of these, 30 were irrigated with 2% chlorhexidine (CHX) gluconate (group I) and 30 with 9% etidronic acid (group II). Two microbiological samples were collected with sterile paper points from the canal in both groups during the pulpectomy process-first after access opening and before the first irrigation (S1), and second after instrumentation and final irrigation, before filling (S2). The presence of Enterococcus faecalis was determined using colony-forming units per milliliter (CFU/mL) in all samples (S1 and S2). After analyzing the samples before and after irrigation in groups I and II, there was a statistically significant reduction in CFU/mL (p < 0.05). Group II had a statistically significant advantage when the two groups were compared after irrigation. As a result, etidronic acid can be recommended as a pulpectomy irrigating solution for necrotic primary teeth. Supraja AN, Arali V, Rapala H, et al. Evaluation of Antimicrobial Efficacy of Etidronic Acid against Enterococcus faecalis in Primary Teeth: An In Vivo Study. Int J Clin Pediatr Dent 2024;17(4):433-436.

Exploring wound management in dental pulp: Utilizing single-cell RNA sequencing for global transcriptomic analysis in healthy and inflamed pulpal tissues.

The process of wound healing in the dental pulp is characterized by intricate interplay of signalling cascades, cellular responses, and extracellular matrix (ECM). The objective of this research was to examine the intricate interaction between signalling cascades, cellular responses, and extracellular matrix (ECM) dynamics that comprise the wound healing process of dental pulp. We conducted a controlled laboratory analysis of transcriptomic landscape of dental pulp tissues, including both healthy and inflamed samples, utilizing single-cell RNA sequencing. We identified significant change in cellular composition under carious conditions by analysing samples from 50 patients. Specifically, the proportion of immune cells increased from 25% to 40%, while the proportion of fibroblasts decreased from 20% to 10%. A transition towards ECM remodelling and fibrosis was indicated by this change. In addition, substantial increase inexpression of critical genes including COL1A1, FN1, IL-1B, IL-6 and TNC was detected, indicating that the extracellular matrix (ECM) was actively remodelled and that a robust inflammatory response was present, both of which are vital for tissue repair. Increased cell-cell interactions among B cells, plasma cells, macrophages and MSCs, and fibroblasts were highlighted in our study, demonstrating the intricate cellular dynamics that occur in response to dental pulp injury. The knowledge gained regarding the cellular and molecular processes underlying pulp wound healing contributed to the advancement of knowledge regarding pulp pathology and regeneration. Moreover, it established a foundation for creation of targeted therapeutic interventions that seek to maximize pulp repair and regeneration. This study represented noteworthy achievement in the field of dental surgery, establishing a solid groundwork for subsequent investigations into regenerative medicine, wound healing, and dental tissue restoration.

Teaching pulpectomy in paediatric dentistry: A national cross-sectional survey of dental schools in Brazil.

Pulpectomy is used to treat primary teeth with irreversibly inflamed or necrotic pulp tissue. There is, however, a lack of consensus on clinical protocols for teaching pulpectomy at dental schools. To determine what faculty members at Brazilian dental schools are teaching about pulpectomy in primary teeth. A cross-sectional, observational study was conducted using a 39-question survey available via the Google Forms® platform. A snowball sampling strategy was used for recruitment. Invitations to participate were sent via e-mail, WhatsApp® and Instagram®. The data were analysed descriptively. A total of 177 (58.4%) responses were obtained. Most faculty members recommended the use of Kerr hand files (66.1%), and 1% sodium hypochlorite was the most common choice for the irrigating solution (35.3%). Iodoform pastes were the first choice of faculty members (41.6%), and 60.5% of the faculty members recommended composite resin as the definitive restoration. Similarities were found in the teaching of pulpectomy for primary teeth among faculty members at dental schools in Brazil.

Partial pulpotomy success in primary molars followed up for 24 months: A randomized controlled clinical trial using mineral trioxide aggregate, biodentine, and acemannan.

Finding the best treatment approach and suitable capping materials in primary molars with deep carious lesions remains unresolved. To compare the success rates of partial pulpotomy in deep caries lesions in primary molars treated with mineral trioxide aggregate (MTA), biodentine, or acemannan for 6-24 months. A parallel-design, non-inferiority randomized controlled clinical trial was performed. Ninety mandibular primary molars from 65 children meeting the criteria, aged 3-8 years, were included. After inflamed pulp tissue removal and hemostasis, each tooth was randomly allocated into the MTA control group, or the biodentine or acemannan experimental group (N = 30 per group). All teeth were restored with a stainless steel crown. The outcomes were evaluated for 6-24 months. A generalized estimating equation model was used to compare the overall success rate in each group. After 24 months, 58 children (83 teeth) were available for evaluation. The results indicated that the success rate in the MTA, biodentine, and acemannan groups was 83.3%, 76.9%, and 74.1%, respectively. No significant difference in success rates among groups, however, was observed at the 6- to 24-month follow-ups (at 24th month, p = .30). There was no statistically significant difference between MTA, biodentine, or acemannan in the partial pulpotomy success after 24 months.

The use of medicaments in the management of symptomatic irreversible pulpitis: A community-based cohort study.

To investigate patient outcomes from either pulpotomy or pulpectomy for the management of symptomatic irreversible pulpitis, with and without application of antibiotic/corticosteroid pastes in urgent primary dental care settings in the United Kingdom. All patients receiving intervention for symptomatic irreversible pulpitis in three different primary care settings were invited to participate. Pre-operatively, data regarding patients' numerical ratings scale (NRS), pain score (0-10), analgesic use, oral-health impact profile-14 (OHIP-14) and need for time away from work were collected. For 7 days post-operatively, participants recorded their NRS pain score, global rating of change score, medication use and their ability to work. Analysis used a mixed-effects model with post hoc Tukey's multiple comparisons test for continuous data and chi-squared or Fisher's exact test for categorical data. To test the effect of the corticosteroid/antibiotic paste, pulpectomy and pulpotomy groups were combined following Mantel-Haenszel stratified analysis or a weighted average of the difference between pulpotomy and pulpectomy with and without the use of corticosteroid/antibiotic paste. A binary composite score was constructed using pre- and post-operative data, whereby overall treatment success was defined as: (i) patients did not return for treatment due to pain by day seven; (ii) at day three, there was a 33% (or 2-points) reduction in NRS pain score; (iii) there was a change score of +3 in global rating; (iv) the patient was no longer using analgesia and able to return to work. Eighty-five participants were recruited, with 83 completing follow up. Overall treatment success was 57%, with 25% of participants returning for more treatment due to inadequate pain relief. Overall treatment success did not differ between the two groups (p = .645), although patients self-reported greater improvement with an antibiotic/corticosteroid dressing for global rating of change (p = .015). This study identified limited evidence of improved outcomes using antibiotic/corticosteroid dressings in the management of symptomatic irreversible pulpitis in the emergency setting. Further clinical research is needed to understand if these medications are beneficial in affording pain relief, above that of simple excision of irreversibly inflamed pulp tissue.

Autophagy induced by hypoxia in pulpitis is mediated by HIF-1α/BNIP3

ObjectiveHypoxia-inducible factor-1α (HIF-1α) and its downstream factor, 19 kDa BCL-2 interacting protein 3 (BNIP3), promote cellular autophagy under hypoxic conditions. However, their roles in pulpitis are unclear. Therefore, the changes in inflammatory response and autophagy levels caused by hypoxia during pulpitis were evaluated. Additionally, the regulatory mechanism of HIF-1α/BNIP3 in cellular autophagy in pulpitis was explored. DesignPulp from dental pulp tissues of healthy individuals and patients with pulpitis (n = 10) were exposed and combined with a low oxygen simulation chamber to construct pulpitis (n = 6), hypoxia (n = 6), and hypoxia+pulpitis (n = 6) rat models. Hematoxylin and eosin and immunohistochemical staining were used to detect the localization and expression levels of HIF-1α, BNIP3, and autophagy marker protein, LC3B. Transmission electron microscopy was used to confirm autophagosome formation. An in vitro hypoxic model of human dental pulp cells was established, and HIF-1α chemical inhibitor 3-(5′-hydroxymethyl-2′-furyl)− 1-benzylindazole (YC-1) was administered. Immunofluorescence and western blotting were used to detect the localization and protein levels of HIF-1α, BNIP3, and LC3B. ResultsAutophagy is significantly increased and HIF-1α and BNIP3 are elevated in inflamed dental pulp tissue. Both pulp exposure and hypoxia intervention cause inflammatory reactions in rat dental pulp tissue, accompanied by the autophagy activation. Hypoxia significantly enhances HIF-1α/BNIP3 and autophagy activation. BNIP3 downregulates and autophagy reduces after treatment with YC-1. ConclusionsIn pulpitis, activation of the HIF-1α/BNIP3 signaling pathway driven by hypoxia leads to increased autophagy. This provides a new molecular explanation for autophagy activation in apical periodontitis and new insights into the pathogenesis of the disease.

Evaluation of Antimicrobial Efficacy of 3.8% Silver Diamine Fluoride as a Root Canal Irrigant against Enterococcus Faecalis in Primary Teeth: A Randomised Clinical Trial

Introduction: During a pulpectomy, the infected or inflamed pulp tissues are removed, and the root canal is thoroughly cleaned with mechanical instrumentation and copious irrigation. Various endodontic irrigants are available, such as Sodium Hypochlorite (NaOCl), Chlorhexidine (CHX) gluconate, Ethylene Diamine Tetra Acetic Acid (EDTA), Mixture of doxycycline, citric acid, and a detergent (MTAD), etc. Among these, CHX gluconate is widely used as an endodontic irrigant and medicament due to its antibacterial effect and substantivity. Enterococcus faecalis is the most common bacterial species found in necrotic teeth, with high viability and antibiotic resistance. A 3.8% Silver Diamine Fluoride (SDF) has antimicrobial properties and has been shown to eliminate E. faecalis from the root canals of permanent teeth. However, there are no studies in the literature that have evaluated its efficacy as a root canal irrigant in primary teeth. Aim: To evaluate the antimicrobial efficacy of 3.8% SDF against E. faecalis in primary teeth. Materials and Methods: This was a in-vivo double-blinded randomised clinical trial conducted at Department of Paediatric and Preventive Dentistry, GSL Dental College and Hospital, Rajahmundry, Andhra Pradesh, India in children aged 3-8 years old. The study included 60 primary teeth that required pulpectomy. The teeth were divided into two groups and irrigated: 30 teeth with 3.8% SDF (Group I) and 30 teeth with 2% CHX (Group II). In all cases, two microbiological samples were taken using sterile absorbent paper points: the first after access opening and the second after the final irrigation. All samples were assessed using the agar plate method. The results were analysed statistically using a Student's paired t-test. Results: After analysing the pre- and postirrigation samples, there was a statistically significant reduction in Colony Forming Units (CFU)mL (p&lt;0.05) in both groups. When comparing the two groups, no statistical difference was observed in the percentage reduction of bacterial colonies (p&gt;0.05). Conclusion: The reduction in CFU/mL of E. faecalis was comparable in both groups. Thus, 3.8% SDF can be used as an alternative root canal irrigant to 2% CHX.

Effect of Inflamed Pulp Tissue Extirpation on Levels of Inflammatory Neuropeptides in Human Saliva

Effect of Inflamed Pulp Tissue Extirpation on Levels of Inflammatory Neuropeptides in Human Saliva

MicroRNA-181b attenuates lipopolysaccharide-induced inflammatory responses in pulpitis via the PLAU/AKT/NF-κB axis

ObjectiveThis study aimed to investigate the role and underlying mechanisms of microRNA (miRNA)-181b in the inflammatory response in pulpitis. MethodsQuantitative reverse-transcription polymerase chain reaction (qRT-PCR), fluorescence in situ hybridization (FISH), and immunofluorescence techniques were used to determine the miRNA-181b and urokinase-type plasminogen activator (PLAU) expression levels in inflamed human dental pulp tissues (HDPTs) and lipopolysaccharide (LPS)-stimulated human dental pulp cells (hDPCs). The targets of miRNA-181b were identified and confirmed using a bioinformatics analysis, RNA sequencing, and dual-luciferase gene reporter assays. The effect of miRNA-181b or PLAU on proinflammatory cytokine expression in hDPCs was examined using qRT-PCR and western blotting. RNA sequencing was conducted to examine the signaling pathways implicated in miRNA-181b-mediated pulpitis. Western blotting and qRT-PCR were used to determine the miRNA-181b /PLAU/AKT/NF-κB signaling axis in pulpitis. A rat pulpitis model was created to observe the histopathological changes in the dental pulp tissue after the topical application of miRNA-181b agomir. ResultsA significant decrease in miRNA-181b and an increase in PLAU were observed in HDPTs compared to the healthy controls, and these two factors showed a negative correlation. MiRNA-181b directly targeted PLAU. The miRNA-181b inhibitor resulted in a significant upregulation of IL-1β, IL-6 and TNF-α, whereas the knockdown of PLAU reversed this proinflammatory effect. Conversely, PLAU overexpression prevented the anti-inflammatory effects of the miRNA-181b mimics. Mechanistically, miRNA-181b inhibited the AKT/NF-κB pathway by targeting PLAU. In vivo application of the miRNA-181b agomir to inflamed pulp tissue alleviated inflammation. ConclusionMiRNA-181b targets PLAU, negatively regulating pro-inflammatory cytokine expression via the AKT/NF-κB signaling pathway.

Dental pulp cells cocultured with macrophages aggravate the inflammatory conditions stimulated by LPS

BackgroundPulp inflammation is complex interactions between different types of cells and cytokines. To mimic the interactions of different types of cells in inflamed dental pulp tissues, dental pulp cells (DPCs) were cocultured with different ratios of macrophages (THP-1) or LPS treatment.MethodsDPCs were cocultured with various ratios of THP-1, then photographed cell morphology and determined cell viability by MTT assay at preset times. Total RNA was also extracted to measure the inflammation marker-IL-6 and IL-8 expressions by RT-Q-PCR. The DPCs and THP-1 were treated with 0.01 – 1μg/ml lipopolysaccharide (LPS) and extract RNA at preset times, and detected IL-6 and IL-8 expression. DPCs were cocultured with various ratios of THP-1 with 0.1 μg/mL LPS, and detected IL-6 and IL-8 expression after 24 and 48 h. The data were analyzed by unpaired t-test or Mann-Whitney test. Differences were considered statistically significant when p < 0.05.ResultsTHP-1 and DPCs coculture models did not suppress the viability of DPCs and THP-1. Cocultured with various ratios of THP-1 could increase IL-6 and IL-8 expressions of DPCs (p = 0.0056 - p < 0.0001). The expressions of IL-6 and IL-8 were stronger in higher ratio groups (p = 0.0062 - p < 0.0001). LPS treatment also induced IL-6 and IL-8 expressions of DPCs and THP-1 (p = 0.0179 – p < 0.0001 and p = 0.0189 – p < 0.0001, separately). Under the presence of 0.1 μg/mL LPS, DPCs cocultured with THP-1 for 24 h also enhanced IL-6 and IL-8 expression (p = 0.0022). After cocultured with a higher ratio of THP-1 for 48 h, IL-6 and IL-8 expressions were even stronger in the presence of LPS (p = 0.0260).ConclusionsCoculturing dental pulp cells and macrophages under LPS treatment aggravate the inflammatory process. The responses of our models were more severe than traditional inflamed dental models and better represented what happened in the real dental pulp. Utilizing our models to explore the repair and regeneration in endodontics will be future goals.

Guanylate-binding protein 5-mediated cell-autonomous immunity suppresses inflammation in dental pulpitis: Aninvitro study.

Guanylate-binding protein 5 (GBP5) is an interferon (IFN)-inducible GTPase that plays a crucial role in the cell-autonomous immune response against microbial infections. In this study, we investigated the immunoregulatory role of GBP5 in the pathogenesis of dental pulpitis. Gene-set enrichment analysis (GSEA) was utilized to evaluate the IFN-γ signalling pathway, and the differential expression of GBP mRNA in normal versus inflamed dental pulp tissues was screened, based on Gene Expression Omnibus (GEO) datasets associated with pulpitis. Both normal pulp tissues and inflamed pulp tissues were used for experiments. The expression of IFNs and GBPs was determined by qRT-PCR. Immunoblotting and double immunofluorescence were performed to examine the cellular localization of GBP5 in dental pulp tissues. For the functional studies, IFN-γ priming or lentivirus vector-delivered shRNA was used to, respectively, overexpress or knock down endogenous GBP5 expression in human dental pulp stem cells (HDPSCs). Subsequently, LPS was used to stimulate HDPSCs (overexpressing or with knocked-down GBP5) to establish an invitro model of inflammation. qRT-PCR and ELISA were employed to examine the expression of proinflammatory cytokines (IL-6, IL-8 and IL-1β) and cyclooxygenase 2 (COX2). Every experiment has three times of biological replicates and three technical replicates, respectively. Statistical analysis was performed using the Student's t-test and one-way ANOVA, and a p-value of <.05 was considered statistically significant. GSEA analysis based on the GEO dataset revealed a significant activation of the IFN-γ signalling pathway in the human pulpitis group. Among the human GBPs evaluated, GBP5 was selectively upregulated in inflamed dental pulp tissues and predominantly expressed in dental pulp cells. Invitro experiments demonstrated that IFN-γ robustly induced the expression of GBP5 in HDPSCs. Knockdown of GBP5 expression in HDPSCs significantly amplified the LPS-induced upregulation of inflammatory mediators (IL-6, IL-8, IL-1β and COX2) both with and without IFN-γ priming. Our findings demonstrated that GBP5 partook in the pathogenesis of dental pulpitis. The involvement of GBP5 in pulpitis appeared to coordinate the regulation of inflammatory cytokines. Knockdown of GBP5 contributed to the exacerbation of LPS-mediated inflammation.

LIF Aggravates Pulpitis by Promoting Inflammatory Response in Macrophages.

Leukemia inhibitory factor (LIF) has been recognized as a novel inflammatory modulator in inflammation-associated diseases. This study aimed to investigate the modulation of LIF in dental pulp inflammation. Experimental pulpitis was established in wild-type (WT) and Lif-deficient (Lif-/-) mice. Histological and immunostaining analyses were conducted to assess the role of LIF in the progression of pulpitis. Mouse macrophage cell line (RAW264.7) was treated with LPS to simulate an inflammatory environment. Exogenous LIF was added to this system to examine its modulation in macrophage inflammatory response in vitro. Primary bone marrow-derived macrophages (BMDMs) from WT and Lif-/- mice were isolated and stimulated with LPS to confirm the effect of Lif deletion on macrophage inflammatory response. Supernatants from LIF and LPS-treated human dental pulp cells (hDPCs) were collected and added to macrophages. Macrophage chemotaxis was assessed using transwell assays. The results showed an increased expression of LIF and LIFR with the progression of pulpitis, and LIFR was highly expressed in macrophages. Lif deficiency alleviated experimental pulpitis with the reduction of pro-inflammatory cytokines and macrophage infiltration. Exogenous LIF promoted inflammatory response of LPS-induced macrophages through a STAT3/p65-dependent pathway. Consistently, Lif deletion inhibited macrophage inflammatory response in vitro. Supernatants of LIF-treated hDPCs enhanced macrophage migration in LPS-induced inflammatory environment. Our findings demonstrated that LIF aggravates pulpitis by promoting macrophage inflammatory response through a STAT3/p65-dependent pathway. Furthermore, LIF plays a crucial role in driving the recruitment of macrophages to inflamed pulp tissue by promoting chemokine secretion in DPCs.

Investigating In Situ Expression of Neurotrophic Factors and Partner Proteins in Irreversible Pulpitis

IntroductionIn situ assessments of neurotrophic factors and their associated molecular partners have not been explored to date, particularly in humans. The present investigation aimed to explore the expressional dysregulation of neurotrophic factors (nerve growth factor [NGF], brain derived neurotrophic factor [BDNF], and NT4/5), their receptors (TrkA and TrkB), and their modulators (USP36 and Nedd4-2) directly in irreversibly inflamed human pulp tissues. MethodsForty samples each of healthy and irreversibly inflamed pulp were extirpated for the study. Immunohistochemical examinations were carried out for the anatomic changes and expression of neurotrophic factors and partner proteins. Expression was digitally quantified using the IHC profiler module of ImageJ and deduced as optical density. Statistical analyses were carried out by GraphPad Prism. ResultsDecrease in nuclear and vessel diameters was observed in irreversibly inflamed pulp tissues. NGF and BDNF were found to be significantly upregulated in symptomatic irreversible pulpitis (SIP), whereas no significant difference was observed in the expression of TrkA and TrkB. Expression of Nedd4-2, USP36, and TrkA was found positively correlated with the NGF in healthy pulp tissues. However, in SIP, positive correlation was only observed between the expression of USP36 and NGF. Among the ligands, BDNF expression was found positively correlated with NGF in healthy pulp but not with NT4/5. In the case of SIP, no correlation was observed between any neurotrophic factors. ConclusionsUpregulation of NGF, BDNF, USP36 and Nedd4-2 in SIP indicates dysregulation in the molecular events underlying the disease biology and could be exploited as potential markers for the disease diagnosis.

Evaluation of oxidative stress cycle in healthy and inflamed dental pulp tissue: a laboratory investigation.

The purpose of this study was to investigate the oxidative stress cycle consisting of reactive oxygen molecules (ROS), glutathione (GSH) and glutathione S-transferase (GST) in caries-related pulp inflammation. Fifty-four pulp tissue samples were collected from healthy donors with the diagnosis of reversible pulpitis, symptomatic irreversible pulpitis, and healthy pulp. Twelve pulp samples from each group were homogenized and total protein, ROS, GSH, and GST were measured by spectrophotometer. The remaining 6 samples from each group were prepared for paraffin block and used for the histopathologic and immunohistochemical evaluation of oxidative stress parameters and TUNEL labeling. Data were analyzed statistically. The results revealed that total protein levels significantly decreased; however, ROS levels increased in both reversible and irreversible pulpitis compared to the healthy pulp (p < 0.01). Also, as inflammation increases, GST enzyme levels decrease while GSH levels increase significantly (p < 0.05). It was found that the number of TUNEL (+) cells was increased in irreversible pulpitis samples compared to healthy and reversible pulpitis groups (p < 0.05). GSTP1 and GSH immunoreactivity were also observed in irreversible pulpitis samples. It has been revealed that caries-related inflammation alters the oxidative stress cycle in dental pulp tissue. The increase in GSH levels in the inflamed dental pulp due to the increase in ROS levels may improve the defensive ability of the dental pulp. There is a relationship between oxidative stress and inflammation. Control of excessive oxidative stress in pulpitis can stimulate reparative and regenerative processes. The present findings may provide an overview of the management of oxidative stress in cases with pulpitis during regenerative treatments.