Radiation-induced fibrosis: Mechanisms and therapeutic strategies from an immune microenvironment perspective

Radiation-induced fibrosis (RIF) is a severe chronic complication of radiotherapy (RT) manifested by excessive extracellular matrix (ECM) components deposition within the irradiated area. The lung, heart, skin, jaw, pelvic organs and so on may be affected by RIF, which hampers body functions and quality of life. There is accumulating evidence suggesting that the immune microenvironment may play a key regulatory role in RIF. This article discussed the synergetic or antagonistic effects of immune cells and mediators in regulating RIF's development. Several potential preventative and therapeutic strategies for RIF were proposed based on the immunological mechanisms to provide clinicians with improved cognition and clinical treatment guidance.

Inhibition of IL-17 signaling in macrophages underlies the anti-arthritic effects of halofuginone hydrobromide: Network pharmacology, molecular docking, and experimental validation

BACKGROUND

Rheumatoid arthritis (RA) is a prevalent autoimmune disease marked by chronic synovitis as well as cartilage and bone destruction. Halofuginone hydrobromide (HF), a bioactive compound derived from the Chinese herbal plant Dichroa febrifuga Lour., has demonstrated substantial anti-arthritic effects in RA. Nevertheless, the molecular mechanisms responsible for the anti-RA effects of HF remain unclear.

METHODS

This study employed a combination of network pharmacology, molecular docking, and experimental validation to investigate potential targets of HF in RA.

RESULTS

Network pharmacology analyses identified 109 differentially expressed genes (DEGs) resulting from HF treatment in RA. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses unveiled a robust association between these DEGs and the IL-17 signaling pathway. Subsequently, a protein-protein interaction (PPI) network analysis revealed 10 core DEGs, that is, EGFR, MMP9, TLR4, ESR1, MMP2, PPARG, MAPK1, JAK2, STAT1, and MAPK8. Among them, MMP9 displayed the greatest binding energy for HF. In an in vitro assay, HF significantly inhibited the activity of inflammatory macrophages, and regulated the IL-17 signaling pathway by decreasing the levels of IL-17 C, p-NF-κB, and MMP9.

CONCLUSION

In summary, these findings suggest that HF has the potential to inhibit the activation of inflammatory macrophages through its regulation of the IL-17 signaling pathway, underscoring its potential in the suppression of immune-mediated inflammation in RA.

Deciphering the pharmacological mechanisms of Fraxini Cortex for ulcerative colitis treatment based on network pharmacology and in vivo studies

BACKGROUND

Ulcerative colitis (UC) is a common type of inflammatory bowel disease. Due to the elusive pathogenesis, safe and effective treatment strategies are still lacking. Fraxini Cortex (FC) has been widely used as a medicinal herb to treat some diseases. However, the pharmacological mechanisms of FC for UC treatment are still unclear.

METHODS

An integrated platform combining network pharmacology and experimental studies was introduced to decipher the mechanism of FC against UC. The active compounds, therapeutic targets, and the molecular mechanism of action were acquired by network pharmacology, and the interaction between the compounds and target proteins were verified by molecular docking. Dextran sulfate sodium (DSS)-induced colitis model was employed to assess the therapeutic effect of FC on UC, and validate the molecular mechanisms of action predicted by network pharmacology.

RESULTS

A total of 20 bioactive compounds were retrieved, and 115 targets were predicted by using the online databases. Ursolic acid, fraxetin, beta-sitosterol, and esculetin were identified as the main active compounds of FC against UC. PPI network analysis identified 28 FC-UC hub genes that were mainly enriched in the IL-17 signaling pathway, the TNF signaling pathway, and pathways in cancer. Molecular docking confirmed that the active compounds had high binding affinities to the predicted target proteins. GEO dataset analysis showed that these target genes were highly expressed in the UC clinical samples compared with that in the healthy controls. Experimental studies showed that FC alleviated DSS-induced colitis symptoms, reduced inflammatory cytokines release, and suppressed the expression levels of IL1β, COX2, MMP3, IL-17 and RORγt in colon tissues.

CONCLUSION

FC exhibits anti-UC properties through regulating multi-targets and multi-pathways with multi-components. In vivo results demonstrated that FC alleviated DSS-induced colitis.

Biological Properties of Dental Pulp Stem Cells Isolated from Inflamed and Healthy Pulp and Cultured in an Inflammatory Microenvironment

INTRODUCTION

The aim of this study was to assess whether the biological characteristics of dental pulp stem cells (DPSCs), such as viability, adhesion to dentin, mineralization, and release of immunomodulatory cytokines, are affected by the inflammatory status of the donor tissue and/or the sustained inflammatory environment.

METHODS

DPSCs were isolated from pulps from 3 caries-free teeth (healthy or hDPSCs), and from 3 teeth with irreversible pulpitis or deep caries (unhealthy DPSCs or uDPSCs). The cells were cultured in odontogenic and osteogenic media with or without lipopolysaccharides. Viability was analyzed by MTT assay at days 1, 3, 5, and 7; adhesion to dentin was evaluated through an environmental scanning electron microscope after 48 hours and through MTT assay; mineralization was analyzed with alizarin red staining after 21 days; and the release of proinflammatory (interleukin 6) and immunosuppressive cytokines (interleukin 10) was measured with the enzyme-linked immunosorbent assay after 24 hours and 7 days.

RESULTS

The inflammatory status of the pulp significantly reduced the viability and mineralization capacity of the DPSCs, although it did not affect the adhesion capacity to dentin or the secretion of the proinflammatory interleukin. The inflammatory microenvironment (lipopolysaccharide) only had a significant impact on the secretion of interleukin 6, which was augmented after 7 days.

CONCLUSIONS

The inflammatory status of the dental pulp should be taken into account when the use of DPSCs is intended either for research and/or for application in reparative or regenerative therapies.

Salidroside protects against intestinal barrier dysfunction in septic mice by regulating IL‑17 to block the NF‑κB and p38 MAPK signaling pathways

Sepsis is a systemic inflammatory response syndrome, mainly caused by infection or suspected infectious factors. The intestine is not only one of the most easily involved organs in the course of sepsis, but also the dynamic organ for the course of sepsis. The present study investigated the protective effect and mechanism of salidroside on intestinal barrier dysfunction of septic mice. Briefly, C57BL/6 mice were used to establish a septic model and then administered with salidroside. The ileum tissues of mice were examined by histopathological examination. Fluorescein isothiocyanate-dextran concentration was measured. IL-17, IL-6, IL-13 and TNF-α levels in ileum tissues and NF-κB and p38 MAPK activations were detected by ELISA and the expressions of NF-κB p65 and p38 MAPK protein with their phosphorylation and intestinal tight junction proteins were gauged by western blotting. The above assays were performed again to investigate the effect of anti-IL-17A and salidroside (160 mg/kg) alone or in combination. The septic model induced the ileum tissue injury, increased intestinal permeability and TNF-α, IL-17 and IL-6 levels, activated NF-κB and p38 MAPK pathways, promoted the expressions of NF-κB p65 and p38 MAPK and their phosphorylation, while suppressing the levels of IL-13 and intestinal tight junction proteins. Salidroside and anti-IL-17A partially reversed the above effects of septic model, which in combination further strengthened the reversing effect. Collectively, salidroside protected against intestinal barrier dysfunction in septic mice by downregulating IL-17 level to inhibit NF-κB and p38 MAPK signaling pathways, thus providing a new treatment direction.

Potentiality and Inflammatory Marker Expression Are Maintained in Dental Pulp Cell Cultures from Carious Teeth

Objectives: This investigation aimed to isolate and culture human dental pulp cells from carious teeth (cHDPCs) and compare their growth characteristics, colony-forming efficiency, mineralization potential and gene expression of Toll-like receptors (TLR)-2, TLR-4, TLR-9, tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, IL-17A, 1L-17R, IL-23A, nuclear factor-kappa B (NF-κB), mitogen-activated protein kinase (MAPK1), dentin matrix protein (DMP)-1, dentin sialophospho protein (DSPP), sex determining region Y-box 2 (SOX2) and marker of proliferation Ki-67 (MKi67) with cells isolated from healthy or non-carious teeth (ncHDPCs). Methods: Pulp tissues were obtained from both healthy and carious teeth (n = 5, each) to generate primary cell lines using the explant culture technique. Cell cultures studies were undertaken by generating growth curves, a colony forming unit and a mineralization assay analysis. The expression of vimentin was assessed using immunocytochemistry (ICC), and the gene expression of above-mentioned genes was determined using quantitative real-time reverse-transcription polymerase chain reaction. Results: ncHDPCs and cHDPCs were successfully isolated and cultured from healthy and inflamed human dental pulp tissue. At passage 4, both HDPC types demonstrated a typical spindle morphology with positive vimentin expression. No statistical difference was observed between ncHDPCs and cHDPCs in their growth characteristics or ability to differentiate into a mineralizing phenotype. ncHDPCs showed a statistically significant higher colony forming efficiency than cHDPCs. The gene expression levels of TLR-2, TLR-4, TLR-9, TNF-α, IL-6, IL-8, IL-17R, IL-23A, NF-κB, MAPK1, DMP1, DSPP and SOX2 were significantly higher in cHDPCs compared with ncHDPC cultures. Conclusion: cHDPCs retain their differentiation potential and inflammatory phenotype in vitro. The inflamed tooth pulp contains viable stem/progenitor cell populations which have the potential for expansion, proliferation and differentiation into a mineralizing lineage, similar to cells obtained from healthy pulp tissue. These findings have positive implications for regenerative endodontic procedures.

The Mechanism of Inflammatory Factors and Soluble Vascular Cell Adhesion Molecule-1 Regulated by Nuclear Transcription Factor NF-κB in Unstable Angina Pectoris

This work is aimed at exploring the mechanism of inflammatory factors and soluble vascular cell adhesion molecule-1 (sVCAM-1) regulated by nuclear transcription factor-κB (NF-κB) in unstable angina pectoris (UAP). 60 patients with unstable angina pectoris (UAP), 60 patients with stable angina pectoris (SAP), and some healthy people (controls) were selected and included. Peripheral venous blood (PVB) of all subjects was collected to detect blood routine. The enzyme-linked immunosorbent assay (ELISA) was adopted for detecting Visfatin, sVCAM-1, soluble intervascular cell adhesion molecule-1 (sICAM-1), and inflammatory factors; flow cytometry (FCM) was to detect the CD63 and CD62P; real-time fluorescence quantitative polymerase chain reaction (rt-qPCR) was employed to detect the NF-κB1, NF-κB2, and REL mRNA. The hs-CRP results of UAP group, SAP group, and control group were 11.12 ± 1.5 mg/L, 10.23 ± 1.3 mg/L, and 4.51 ± 1.1 mg/L, respectively. The CD62P results of UAP group, SAP group, and control group were 16.07 ± 2.5%, 11.09 ± 1.8%, and 22.15 ± 0.4%, respectively. The high-sensitivity C-reactive protein (hs-CRP), inflammatory factors (IL-6, IL-17, IL-23, IL-1β, and tumor necrosis factor α (TNF-α)), CD63, CD62P, NF-κB1, NF-κB2, and REL mRNA were obviously higher in the SAP group compared than the indicator values in the control group (P < 0.05). The relative REL expression results of UAP group, SAP group, and control group were 3.77 ± 1.5, 2.2 ± 0.6, and 1 ± 0.4, respectively. The inflammatory factors, Visfatin, sVCAM-1, sICAM-1, CD63, CD62P, NF-κB1, NF-κB2, and REL mRNA in the UAP group showed higher levels in contrast to the other two groups (P < 0.05). In summary, UAP patients had marked activation of the IL-23/IL-17 inflammatory axis, high expressions of sVCAM-1 and sICAM-1, and activation of the NF-κB pathway. Increase of inflammatory factors and sVCAM-1 regulated by NF-κB was closely correlated with UAP.

Pro- and anti-inflammatory bioactive lipids imbalance contributes to the pathobiology of autoimmune diseases

Autoimmune diseases are driven by T_H17 cells that secrete pro-inflammatory cytokines, especially IL-17. Under normal physiological conditions, autoreactive T cells are suppressed by TGF-β and IL-10 secreted by microglia and dendritic cells. When this balance is upset due to injury, infection and other causes, leukocyte recruitment and macrophage activation occurs resulting in secretion of pro-inflammatory IL-6, TNF-α, IL-17 and PGE2, LTs (leukotrienes) accompanied by a deficiency of anti-inflammatory LXA4, resolvins, protecting, and maresins. PGE2 facilitates T_H1 cell differentiation and promotes immune-mediated inflammation through T_H17 expansion. There is evidence to suggest that autoimmune diseases can be suppressed by anti-inflammatory bioactive lipids LXA4, resolvins, protecting, and maresins. These results imply that systemic and/or local application of LXA4, resolvins, protecting, and maresins and administration of their precursors AA/EPA/DHA could form a potential therapeutic approach in the prevention and treatment of autoimmune diseases.

Role of IL-17 family cytokines in the progression of IPF from inflammation to fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal chronic interstitial lung disease with no established treatment and is characterized by progressive scarring of the lung tissue and an irreversible decline in lung function. Chronic inflammation has been demonstrated to be the pathological basis of fibrosis. Emerging studies have revealed that most interleukin-17 (IL-17) isoforms are essential for the mediation of acute and chronic inflammation via innate and adaptive immunity. Overexpression or aberrant expression of IL-17 cytokines contributes to various pathological outcomes, including the initiation and exacerbation of IPF. Here, we aim to provide an overview of IL-17 family members in the pathogenesis of IPF.

Essential Fatty Acids and Their Metabolites in the Pathobiology of Inflammation and Its Resolution

Arachidonic acid (AA) metabolism is critical in the initiation and resolution of inflammation. Prostaglandin E2 (PGE2) and leukotriene B4/D4/E4 (LTB4/LD4/LTE4), derived from AA, are involved in the initiation of inflammation and regulation of immune response, hematopoiesis, and M1 (pro-inflammatory) macrophage facilitation. Paradoxically, PGE2 suppresses interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) production and triggers the production of lipoxin A4 (LXA4) from AA to initiate inflammation resolution process and augment regeneration of tissues. LXA4 suppresses PGE2 and LTs' synthesis and action and facilitates M2 macrophage generation to resolve inflammation. AA inactivates enveloped viruses including SARS-CoV-2. Macrophages, NK cells, T cells, and other immunocytes release AA and other bioactive lipids to produce their anti-microbial actions. AA, PGE2, and LXA4 have cytoprotective actions, regulate nitric oxide generation, and are critical to maintain cell shape and control cell motility and phagocytosis, and inflammation, immunity, and anti-microbial actions. Hence, it is proposed that AA plays a crucial role in the pathobiology of ischemia/reperfusion injury, sepsis, COVID-19, and other critical illnesses, implying that its (AA) administration may be of significant benefit in the prevention and amelioration of these diseases.

Potential application of immunotherapy for modulation of pulp inflammation: opportunities for vital pulp treatment

Caries results in the demineralization and destruction of enamel and dentine, and as the disease progresses, irreversible pulpitis can occur. Vital pulp therapy (VPT) is directed towards pulp preservation and the prevention of the progression of inflammation. The outcomes of VPT are not always predictable, and there is often a poor correlation between clinical signs and symptoms, and the events occurring at a molecular level. The inflamed pulp expresses increased levels of cytokines, including tumour necrosis factor (TNF)-α, interleukin (IL)-1α, IL-1β, IL-4, IL-6, IL-8, IL-17 and IL-23, which recruit and drive a complex cellular immune response. Chronic inflammation and sustained cytokine release can result in irreversible pulp damage and a decreased capacity for tissue healing. Other chronic inflammatory diseases, such as psoriasis, inflammatory bowel diseases and rheumatoid arthritis, are also characterized by an dysregulated immune response composed of relatively high cytokine levels and increased numbers of immune cells along with microbial and hard-soft tissue destructive pathologies. Whilst anti-cytokine therapies have been successfully applied in the treatment of these diseases, this approach is yet to be attempted in cases of pulp inflammation. This review therefore focuses on the similarities in the aetiology between chronic inflammatory diseases and pulpitis, and explores how anti-cytokine therapies could be applied to manage an inflamed pulp and facilitate healing. Further proof-of-concept studies and clinical trials are justified to determine the effectiveness of these treatments to enable more predictable outcomes in VPT.

Osteocyte-Related Cytokines Regulate Osteoclast Formation and Bone Resorption

The process of bone remodeling is the result of the regulated balance between bone cell populations, namely bone-forming osteoblasts, bone-resorbing osteoclasts, and the osteocyte, the mechanosensory cell type. Osteoclasts derived from the hematopoietic stem cell lineage are the principal cells involved in bone resorption. In osteolytic diseases such as rheumatoid arthritis, periodontitis, and osteoporosis, the balance is lost and changes in favor of bone resorption. Therefore, it is vital to elucidate the mechanisms of osteoclast formation and bone resorption. It has been reported that osteocytes express Receptor activator of nuclear factor κΒ ligand (RANKL), an essential factor for osteoclast formation. RANKL secreted by osteocytes is the most important factor for physiologically supported osteoclast formation in the developing skeleton and in pathological bone resorption such as experimental periodontal bone loss. TNF-α directly enhances RANKL expression in osteocytes and promotes osteoclast formation. Moreover, TNF-α enhances sclerostin expression in osteocytes, which also increases osteoclast formation. These findings suggest that osteocyte-related cytokines act directly to enhance osteoclast formation and bone resorption. In this review, we outline the most recent knowledge concerning bone resorption-related cytokines and discuss the osteocyte as the master regulator of bone resorption and effector in osteoclast formation.

What is the response profile of deciduous pulp fibroblasts stimulated with E. coli LPS and E. faecalis LTA?

Background

Oral fibroblast immunological responses to bacterial stimuli are well known. However, there are few studies about pulp fibroblasts from deciduous teeth (HDPF) responses, which are important for the treatment of pulp infections in children. The aim of this study was to evaluate expression and production of inflammatory cytokines and chemokines by HDPF when challenged with bacterial antigens normally present in advanced caries lesions.

Methods

Triplicate HDPF from 4 children (n = 4; 2 boys and 2 girls) were cultured by explant technique and challenged or not with Escherichia coli lipopolysaccharide/1 μg/mL (EcLPS) or Enterococcus faecalis lipoteichoic acid/1 μg/mL (EfLTA) for 6 and 24 h. Most of published studies employed immortalized cells, i.e., without checking possible gender and genetic variables. mRNA expression and protein production were evaluated by RT-qPCR and ELISA MILLIPLEX®, respectively, for Interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17, Chemokine C-C motif ligand 2/monocyte chemoattractant protein 1 (CCL2/MCP-1), Chemokine C-C motif ligand 3/macrophage inflammatory protein 1-alpha (CCL3/MIP1-α), Chemokine C-C motif ligand 5/ regulated on activation, normal T cell expressed and secreted (CCL5/RANTES), C-X-C motif chemokine 12/ stromal cell-derived factor 1 (CXCL12/SDF-1), Tumor Necrosis Factor-alpha (TNF-α), Interferon-gamma (IFN γ), Vascular Endothelial Growth Factor (VEGF), Colony stimulating factor 1 (CSF-1) and Macrophage colony-stimulating factor (M-CSF).

Results

EcLPS increased IL-1α, IL-1β, IL-8, CCL2, CCL5, TNF-α and CSF-1 mRNA and protein levels while EfLTA was only able to positively regulate gene expression and protein production of IL-8.

Conclusion

The results of the present study confirmed our hypothesis, since pulp fibroblasts from deciduous teeth are capable of increasing gene expression and protein production after being stimulated with EcLPS and EfLTA.

Associations between TAB2 gene polymorphisms and dilated cardiomyopathy in a Chinese population

Aim: The present study aimed to investigate the role of TAB2 gene polymorphisms in dilated cardiomyopathy (DCM) susceptibility and prognosis in a Chinese population. Materials & methods: A total of 343 DCM patients and 451 controls were enrolled and had their blood genotyped. Survival analysis was evaluated with Kaplan-Meier curves and Cox regression analysis. Results: G carriers (AG/GG) and AG genotype of rs237028 had a higher DCM susceptibility as well as a worse DCM prognosis. Additionally, C carriers (CT/CC) of rs652921 and G carriers (TG/GG) of rs521845 had a higher DCM risk and CC homozygote of rs652921 had a worse DCM prognosis. These associations were still significant after adjustment for the Bonferroni correction. Conclusion: TAB2 gene polymorphisms were associated with DCM susceptibility and prognosis in the Chinese population.

Heparin-LL37 complexes are less cytotoxic for human dental pulp cells and have undiminished antimicrobial and LPS-neutralizing abilities

AIM

To investigate whether glycosaminoglycans (GAGs) binding to high-dose LL37 eliminates its cytotoxicity to dental pulp cells (hDPCs) whilst retaining undiminished antimicrobial and LPS-neutralizing abilities.

METHODOLOGY

hDPCs were stimulated with varying concentrations of LL37, and their cell viability was analysed by MTT. Then, high-dose LL37 (10 μmol L^-1 ) was bound to varying concentrations of three GAGs, heparin, chondroitin sulphate and hyaluronic acid, and their cytotoxic effects on hDPCs and antimicrobial effects were evaluated and compared. Furthermore, the LPS-neutralizing ability of heparin (5 μg mL^-1 )-LL37 (10 μmol L^-1 ) complexes, which were found to be less cytotoxic for hDPCs with undiminished antimicrobial ability, was investigated. Statistical analysis was performed using one-way analysis of variance (anova), followed by Dunnett's test. P values below 0.05 were considered significant.

RESULTS

LL37 significantly reduced the cell viability of hDPCs in a dose-dependent manner (P < 0.01). LL37 (10 μmol L^-1 ) binding to heparin within a limited concentration range (2~6 μg mL^-1 ) eliminated the cytotoxicity for hDPCs (P < 0.01) whilst exerting potent antimicrobial effects against Streptococcus mutans, Streptococcus sobrinus, Streptococcus salivarius, Aggegatibacter actinomycetemcomitans and Escherichia coli. LL37 (10 μmol L^-1 ) binding to chondroitin sulphate exhibited similar functions (P < 0.01); however, the effective chondroitin sulphate concentration was highly restricted (3 μg mL^-1 ). LL37 (10 μmol L^-1 ) binding to hyaluronic acid was unable to abrogate the cytotoxicity of LL37 even at higher concentrations (10 and 100 μg mL^-1 ). Moreover, exogenous addition of LPS dose-dependently reduced the amount of LL37 precipitated with the heparin-LL37 agarose beads (P < 0.01), and the released LL37 simultaneously neutralized the pro-inflammatory ability of LPS in macrophages (P < 0.01).

CONCLUSIONS

Heparin-LL37 complexes generated at suitable concentration ratios are easy to make, are less cytotoxic and are broad-range antimicrobial materials that can neutralize LPS by providing LL37 in accordance with the amount of free LPS. They may be a potential treatment to save dental pulp tissue from the acute inflammation exacerbated by invading bacteria and the LPS they release.

Leptin induces IL-6 and IL-8 expression through leptin receptor Ob-Rb in human dental pulp fibroblasts

OBJECTIVE

Leptin, through binding to its special receptor (Ob-Rb), has potent effects on immunity and inflammation. This study aimed to investigate the expression of leptin receptor Ob-Rb in human dental pulp fibroblasts (HDPFs) and the effects of leptin on the production of proinflammatory cytokines of IL-6 and IL-8 by HDPFs.

METHODS

Ob-Rb expression was determined by quantitative real-time PCR (real-time PCR), Western blot and immunofluorescence analyses in cultured HDPFs. Small interfering RNA (siRNA) was transfected into HDPFs to down-regulate the expression of Ob-Rb. Real-time PCR and enzyme-linked immunosorbent assay (ELISA) were used to determine the proinflammatory cytokines of IL-6 and IL-8 levels in leptin-stimulated HDPFs. The involved signalling pathways that mediate the leptin-stimulated production of proinflammatory cytokines were investigated using Western blot and specific signalling inhibitor analyses.

RESULTS

The expression levels of Ob-Rb mRNA and protein were detected in HDPFs. Leptin could stimulate mRNA and protein expression of IL-6 and IL-8 in HDPFs in a concentration-dependent and time-dependent manner. Transfection with siRNA targeting Ob-Rb resulted in remarkable reduction of IL-6 and IL-8 expressions by HDPFs. In accordance with the enhanced expression of proinflammatory cytokines, leptin stimulation resulted in rapid phosphorylation of STAT3, p38 MAPK, ERK and Akt in HDPFs. Inhibiting JAK2/STAT3, p38 MAPK or PI3K/Akt substantially decreased leptin-induced IL-6 production, whereas blocking ERK and p38 MAPK substantially suppressed IL-8 production from leptin-stimulated HDPFs.

CONCLUSIONS

Leptin may up-regulate IL-6 and IL-8 production through binding with Ob-Rb in HDPFs via the activation of different intracellular signalling pathways.

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.

[Interleukin-17 promotes mouse hepatoma cell proliferation by antagonizing interferon-γ]

OBJECTIVE

To investigate the interaction between interleukin-17 (IL-17) and interferon-γ (IFN-γ) and how their interaction affects the growth of mouse hepatoma Hepa1-6 cells.

METHODS

Hepa1-6 cells treated with IL-17 and IFN-γ either alone or in combination were examined for changes in cell proliferation using MTT assay and in cell cycle distribution using flow cytometry. Western blotting was used to detect the protein expression levels of proliferating cell nuclear antigen (PCNA), cyclin D1, P21 and P16 and the phosphorylation of p38MAPK, ERK1/2 and Stat1 in the cells.

RESULTS

Compared with control group, IFN-γ treatment obviously inhibited the growth and proliferation of Hepa1-6 cells, induced cell cycle arrest at G0/G1 phase, reduced the protein expression of PCNA and cyclin D1, and increased the protein expression of P21. IL-17 alone had no effect on the growth of Hepa1-6 cells. In the combined treatment, IL-17 significantly antagonized the effects of IFN-γ. Compared with those treated with IFN-γ alone, the cells with the combined treatment showed significantly decreased G0/G1 cell population, increased the protein expressions of PCNA and cyclin D1, and decreased the protein expression of P21. IL-17 significantly inhibited IFN-γ-induced phosphorylation of p38MAPK and ERK1/2 without affecting the phosphorylation of Stat1.

CONCLUSIONS

IL-17 obviously reverses the antitumor effects of IFN-γ to promote the proliferation of mouse hepatoma cells and accelerate the development of hepatocellular carcinoma.