IL-1β-induced ICAM-1 and IL-8 expression/secretion of dental pulp cells is differentially regulated by IRAK and p38

Exploring the impact of oral bacteria remnants on stem cells from the Apical papilla: mineralization potential and inflammatory response

Introduction

Bacterial persistence is considered one of the main causal factors for regenerative endodontic treatment (RET) failure in immature permanent teeth. This interference is claimed to be caused by the interaction of bacteria that reside in the root canal with the stem cells that are one of the essentials for RET. The aim of the study was to investigate whether prolonged exposure of stem cells from the apical papilla (SCAP) to bacterial remnants of Fusobacterium nucleatum, Actinomyces gerensceriae, Slackia exigua, Enterococcus faecalis, Peptostreptococcaceae yurii, commonly found in infected traumatized root canals, and the probiotic bacteria Lactobacillus gasseri and Limosilactobacillus reuteri, can alter SCAP's inflammatory response and mineralization potential.

Methods

To assess the effect of bacterial remnants on SCAP, we used UV-C-inactivated bacteria (as cell wall-associated virulence factors) and bacterial DNA. Histochemical staining using Osteoimage Mineralization Assay and Alizarin Red analysis was performed to study SCAP mineralization, while inflammatory and osteo/odontogenic-related responses of SCAPs were assessed with Multiplex ELISA.

Results

We showed that mineralization promotion was greater with UV C-inactivated bacteria compared to bacterial DNA. Immunofluorescence analysis detected that the early mineralization marker alkaline phosphatase (ALP) was increased by the level of E. coli lipopolysaccharide (LPS) positive control in the case of UV-C-inactivated bacteria; meanwhile, DNA treatment decreased the level of ALP compared to the positive control. SCAP's secretome assessed with Multiplex ELISA showed the upregulation of pro-inflammatory factors IL-6, IL-8, GM-CSF, IL-1b, neurotrophic factor BDNF, and angiogenic factor VEGF, induced by UV-C-killed bacteria.

Discussion

The results suggest that long term stimulation (for 21 days) of SCAP with UV-C-inactivated bacteria stimulate their mineralization and inflammatory response, while DNA influence has no such effect, which opens up new ideas about the nature of RET failure.

Interferon-β decreases LPS-induced neutrophil recruitment to cardiac fibroblasts

Introduction: Cardiac fibroblasts (CF) are crucial cells in damaged heart tissues, expressing TLR4, IFN-receptor and responding to lipopolysaccharide (LPS) and interferon-β (IFN-β) respectively. While CF interact with immune cells; however, their relationship with neutrophils remains understudied. Additionally, theimpact of LPS and IFN-β on CF-neutrophil interaction is poorly understood. Methods: Isolated CF from adult rats were treated with LPS, with or without IFN-β. This study examined IL-8 secretion, ICAM-1 and VCAM-1 expression, and neutrophil recruitment, as well as their effects on MMPs activity. Results: LPS triggered increased IL-8 expression and secretion, along with elevated ICAM-1 and VCAM-1 expression, all of which were blocked by TAK-242. Pre-treatment with IFN-β countered these LPS effects. LPS treated CF showed higher neutrophil recruitment (migration and adhesion) compared to unstimulated CF, an effect prevented by IFN-β. Ruxolitinib blocked these IFN-β anti-inflammatory effects, implicating JAK signaling. Analysis of culture medium zymograms from CF alone, and CF-neutrophils interaction, revealed that MMP2 was mainly originated from CF, while MMP9 could come from neutrophils. LPS and IFN-β boosted MMP2 secretion by CF. MMP9 activity in CF was low, and LPS or IFN-β had no significant impact. Pre-treating CF with LPS, IFN-β, or both before co-culture with neutrophils increased MMP2. Neutrophil co-culture increased MMP9 activity, with IFN-β pre-treatment reducing MMP9 compared to unstimulated CF. Conclusion: In CF, LPS induces the secretion of IL-8 favoring neutrophils recruitment and these effects were blocked by IFN-. The results highlight that CF-neutrophil interaction appears to influence the extracellular matrix through MMPs activity modulation.

Novel insights of EZH2-mediated epigenetic modifications in degenerative musculoskeletal diseases

Degenerative musculoskeletal diseases (Osteoporosis, Osteoarthritis, Degenerative Spinal Disease and Sarcopenia) are pathological conditions that affect the function and pain of tissues such as bone, cartilage, and muscles, and are closely associated with ageing and long-term degeneration. Enhancer of zeste homolog 2 (EZH2), an important epigenetic regulator, regulates gene expression mainly through the PRC2-dependent trimethylation of histone H3 at lysine 27 (H3K27me3). Increasing evidence suggests that EZH2 is involved in several biological processes closely related to degenerative musculoskeletal diseases, such as osteogenic-adipogenic differentiation of bone marrow mesenchymal stem cells, osteoclast activation, chondrocyte functional status, and satellite cell proliferation and differentiation, mainly through epigenetic regulation (H3K27me3). Therefore, the synthesis and elucidation of the role of EZH2 in degenerative musculoskeletal diseases have attracted increasing attention. In addition, although EZH2 inhibitors have been approved for clinical use, whether they can be repurposed for the treatment of degenerative musculoskeletal diseases needs to be considered. Here, we reviewed the role of EZH2 in the development of degenerative musculoskeletal diseases and brought forward prospects of its pharmacological inhibitors in the improvement of the treatment of the diseases.

Regulation of caries-induced pulp inflammation by NLRP3 inflammasome: A laboratory-based investigation

AIM

To evaluate the expression and function of the nod-like receptor pyrin domain containing 3 (NLRP3) inflammasome in caries induced pulpitis.

METHODOLOGY

NLRP3 expression was determined with immunohistochemistry in the dental pulp and qPCR in dental pulp cells (DPCs). THP-1 macrophages expressing the apoptosis-related speck-like protein (ASC) and green fluorescent protein (GFP) fusion protein were used to assess NLRP3 inflammasome activation by live cell imaging, following treatment with lipopolysaccharide (LPS) and lipoteichoic acid (LTA). Caspase I inhibitor was used to confirm inflammasome activation. An ex-vivo pulpitis model in which the DPCs were co-cultured with THP-1 macrophages was used to study the effect of the NLRP3 inflammasome inhibitor (MCC950), and cytokines were measured using ELISA and multiplex array. Data were analysed using the t-test or anova followed by a Bonferroni post hoc test with the level of significance set at p ≤ .05.

RESULTS

NLRP3 inflammasome was differentially expressed in dental pulp of sound and carious teeth. Treatment of DPCs with LTA significantly upregulates NLRP3 and IL-1 β-expression (p < .05) and in induces more ASC specks formation compared to LPS. IL-β release in response to LTA treatment is significantly reduced with Caspase I inhibitor suggesting inflammasome dependent mechanism (p < .01). NLRP3-specific inhibitor, MCC950, significantly reduced IL-1β and IL-6 in an ex-vivo pulpitis model (p < .01) but had no effect on IL-8 or matrix metalloproteinase-9 (MMP-9).

CONCLUSIONS

Expression and upregulation of NLRP3 inflammasome with caries and LTA treatment suggest a role in caries-induced pulpitis. NLRP3 inhibitor attenuated the release of selective inflammatory cytokines and could be a potential treatment target that merit further investigation.

microRNA-126 inhibits vascular cell adhesion molecule-1 and interleukin-1beta in human dental pulp cells

BACKGROUND

Vascular cell adhesion molecule (VCAM-1) mediates pulpitis via regulating interleukin (IL)-1β. microRNA (miR)-126 was reported to regulate the VCAM-1 under many different pathophysiological circumstances. We investigated variations of miR-126 and VCAM-1 in inflamed patient pulp tissues and determined potential roles of miR-126 in pulpitis using human dental pulp cells (hDPCs) in vitro.

METHODS

We quantitatively measured the transcripts of miR-126 and VCAM-1 in inflamed human pulp tissues using qRT-PCR and compared with those from healthy human pulp tissues. In addition, we transfected miR-126 in hDPCs using plasmid DNA (pDNA)-encoding miR-126 delivered by polyethylenimine (PEI) nanoparticles.

RESULTS

The irreversible pulpitis significantly reduced miR-126 and increased the transcript of VCAM-1 in pulp tissues (p < 0.05). pDNA-encoding miR-126 delivered PEI nanoparticles and effectively upregulated the expression of miR-126 in hDPCs (p < 0.05). The overexpression of miR-126 could effectively suppress the transcripts and protein levels of VCAM-1 and IL-1β induced by Pg-LPS at 100ng/mL in DPCs (p < 0.05).

CONCLUSIONS

miR-126 is involved in pulpitis and downregulated the VCAM-1 and IL-1β in DPCs. miR-126 may be a potential target to attenuate the inflammation of pulpitis.

The Role of microRNAs in Pulp Inflammation

The dental pulp can be affected by thermal, physical, chemical, and bacterial phenomena that stimulate the inflammatory response. The pulp tissue produces an immunological, cellular, and vascular reaction in an attempt to defend itself and resolve the affected tissue. The expression of different microRNAs during pulp inflammation has been previously documented. MicroRNAs (miRNAs) are endogenous small molecules involved in the transcription of genes that regulate the immune system and the inflammatory response. They are present in cellular and physiological functions, as well as in the pathogenesis of human diseases, becoming potential biomarkers for diagnosis, prognosis, monitoring, and safety. Previous studies have evidenced the different roles played by miRNAs in proinflammatory, anti-inflammatory, and immunological phenomena in the dental pulp, highlighting specific key functions of pulp pathology. This systematized review aims to provide an understanding of the role of the different microRNAs detected in the pulp and their effects on the expression of the different target genes that are involved during pulp inflammation.

Peripherally Acting Opioids in Orofacial Pain

The activation of opioid receptors by exogenous or endogenous opioids can produce significant analgesic effects in peripheral tissues. Numerous researchers have demonstrated the expression of peripheral opioid receptors (PORs) and endogenous opioid peptides (EOPs) in the orofacial region. Growing evidence has shown the involvement of PORs and immune cell-derived EOPs in the modulation of orofacial pain. In this review, we discuss the role of PORs and EOPs in orofacial pain and the possible cellular mechanisms involved. Furthermore, the potential development of therapeutic strategies for orofacial pain is also summarized.

Relationship between the higher inflammatory cytokines level in the aqueous humor of Fuchs uveitis syndrome and the presence of cataract

BACKGROUND

This study aims to compare the levels of intraocular cytokines between Fuchs uveitis syndrome (FUS) eyes and the senile cataract eyes. The association between inflammatory cytokine levels and cataract severity in FUS is evaluated to find the possible mechanism of cataract in FUS eyes.

METHODS

A retrospective study of 28 eyes with FUS was performed. Auxiliary examinations were performed, including ophthalmic examinations, laser flare-cell photometry, and levels of inflammatory cytokines in the aqueous humor were measured. The control group included 25 eyes with senile cataract. Data on the aqueous humor inflammatory cytokines were compared between the two groups. The association between the aqueous humor cytokine levels and severity of posterior subcapsular cataract was assessed.

RESULTS

There were 28 eyes with FUS in 27 patients. Unilateral involvement was noted in 26 patients (96.30%). Stellate keratic precipitates (KPs) were noted in 16 eyes (57.14%). Heterochromia was observed in 21.43% of affected eyes. Posterior subcapsular cataract (PSC) was observed in 16 of the 28 eyes. Eyes with FUS had significantly higher aqueous humor (AH) cytokine levels (VEGF, bFGF, IL-6, IL-8 and IL-10) compared with the control eyes (P < 0.05). There was a statistically significant positive correlation between the severity of cataract and IL-6 and IL-8 levels in the AH (τ = 0.664 and 0.634, respectively; P = 0.001, P = 0.002, respectively).

CONCLUSIONS

Expression of VEGF, bFGF, IL-6, IL-8 and IL-10 in the AH of FUS patients was significantly higher than in senile cataract eyes, and the aqueous humor levels of IL-6 and IL-8 were significantly positively associated with the severity of posterior subcapsular cataract. Our results imply that an inflammation mechanism may be involved in the early development of cataract in FUS.