Periodontal disease may induce liver fibrosis in an experimental study on Wistar rats

Periodontitis promotes hepatocellular carcinoma in Stelic Animal model (STAM) mice

Periodontitis is a prevalent oral inflammatory disease that leads to alveolar bone loss and may exert an adverse impact on systemic health. Periodontal disease may be associated with hepatocellular carcinoma (HCC); however, the mechanism of such an association is unknown. In this study, Stelic Animal model (STAM) mice, a model of nonalcoholic steatohepatitis (NASH)-HCC, were induced to develop periodontitis and subjected to histopathological and immunological analyses. HCC progression was greater in STAM mice with experimental periodontitis compared with that in STAM mice without experimental periodontitis. Tumor necrosis factor-α (TNFα), matrix metalloproteinase-9 (MMP9), collagen 1, and angiopoietin-like protein 2 (ANGPTL2) gene expression was significantly increased in the liver of the periodontitis group. ANGPTL2 was previously reported to be involved in the pathogenesis of periodontitis, and HCC and ANGPTL2 protein tended to be more abundant in the pocket epithelium of STAM mice with experimental periodontitis than in control STAM mice. ANGPTL2 levels in the serum of STAM mice with experimental periodontitis tended to be higher than in control STAM mice. Our results indicate that ANGPTL2 is produced in chronically inflamed periodontal tissue and then travels to the liver via the bloodstream where it accumulates to promote the progression of hepatocellular carcinoma.

Effect of bromelain on periodontal destruction and alveolar bone in rats with experimental periodontitis

PURPOSE

Several substances that have anti-inflammatory, antiproteinase, and anti-infective properties have been evaluated as modulators of the inflammatory response in periodontal disease. However, evidence for the anti-inflammatory and antioxidative activities of bromelain is limited. This study evaluated the impact of systemically administered bromelain on the progression of experimental periodontitis.

METHODS

Four equal groups of 32 Wistar albino rats were created as follows (n = 8): control, periodontitis + saline, periodontitis + 5 mg/kg/day bromelain, and periodontitis + 10 mg/kg/day bromelain. To quantify the resorption of bone and bone volume/tissue volume, bone surface / bone volume, and connectivity, lower jawbones were fixed and then scanned using microcomputed tomography (micro CT). Blood samples were taken to measure the macrophage colony-stimulating factor(M-CSF) concentrations, receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG), tumor necrosis factor-alpha (TNF-α), matrix metalloproteinase-8 (MMP-8), interleukin-6(IL-6), glutathione peroxidase (GPx), superoxide dismutase (SOD), and malondialdehyde (MDA). Histopathological assessments were made to examine the tissue.

RESULTS

Treatment with bromelain improved the healing of the periodontium by decreasing the number of leukocytes and ligament deterioration in the gingival connective tissue and by supporting reintegration with alveolar bone. Bromelain used in ligature-induced periodontitis reduced alveolar bone (AB) resorption as measured by microCT; reduced inflammatory parameters such as IL-6 and TNF-α; regulated oxidative-antioxidative processes by increasing GPx and SOD and reducing MDA levels; and regulated AB modeling by decreasing M-CSF, RANKL, and MMP-8 and increasing OPG levels.

CONCLUSION

Bromelain may be an option in periodontal therapy by regulating cytokine levels, improving the healing process, and reducing bone resorption and oxidative stress.

The role of Sirt3-induced autophagy in renal structural damage caused by periodontitis in rats

OBJECTIVE

This research aimed to explore the effect of periodontitis on renal tissues injury in rats and the role of Sirtuin3 (Sirt3) and its regulation of autophagy in this progression.

MATERIAL AND METHODS

Thirty Wistar rats were assigned into three groups: control, periodontitis (P), and periodontitis with gavage administration of Sirt3 activator resveratrol (P + RSV). To induce periodontitis, the wire ligature was placed around the cervical region of the rat maxillary first molar. After 8 weeks, micro-computed tomography (Micro-CT) and hematoxylin and eosin (HE) were used to evaluate the alveolar bone resorption and periodontal inflammation. Serum and urine biochemical indicators were measured to assess renal function. The pathological changes of the kidney were observed via HE and periodic acid Schiff (PAS) staining. Autophagosome was viewed by transmission electron microscopy (TEM). Real-time PCR and western blot were used to test expressions of Sirt3 and autophagy indicators in renal and periodontal tissues, including mammalian target of rapamycin (mTOR), phosphor-mTOR (p-mTOR), BECN1 (Beclin-1), and microtubule-associated protein 1 light chain 3 (LC3).

RESULTS

Alveolar bone destruction, resorption, and periodontal inflammation were observed in the P group (compared with the control group), and the above indexes were significantly improved after RSV intervention; the obvious changes in renal tissue structure in the P group were partially recovered after RSV intervention, while renal functional status was not affected (among the three groups); in addition, the levels of Sirt3 and autophagy in kidney and periodontal tissues of P group were inhibited, manifested as a decrease in the number of autophagosomes (renal tissue) and expressions of autophagy marker Beclin-1 and LC3 conversion rate and an increase in the expression of p-mTOR. After Sirt3 activation (RSV), the above indicators were significantly improved.

CONCLUSION

Periodontitis causes renal structural damage in rats, which may be connected to the effect of Sirt3-induced autophagy.

Evaluation of the oxytocin effect in a rat model with experimental periodontitis

The aim of the present study was to evaluate the inhibitory effects of oxytocin on the development of periodontitis based on its properties against bone loss and resorption. Thirty-two Wistar albino rats were divided into four equal groups: control, periodontitis + saline, periodontitis + 0.5 mg/kg/day oxytocin, and periodontitis + 1 mg/kg/day oxytocin. Periodontitis groups received 4.0 silk ligatures around their cervixes of the right and left mandibular incisors in an "8" shape, kept for 14 days. Animals in oxytocin groups were injected once every day during 14 days with oxytocin. The mandibles were fixed and scanned using microcomputed tomography to quantify bone resorption and volumetric measurements. Blood samples were collected to analyze the concentrations of macrophage colony-stimulating factor (M-CSF), receptor activator of nuclear factor-κΒ ligand (RANKL), osteoprotegerin (OPG), matrix metalloproteinase-8 (MMP-8), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, glutathione peroxidase (GPx), superoxide dismutase (SOD), and malondialdehyde (MDA). Histopathological evaluations were conducted to examine the gingiva and alveolar bone. Oxytocin prevented the development of periodontitis by decreasing ligament deteriorations and leukocytes in the gingival connective tissue and promoting reintegration with the alveolar bone. Bone resorption in all regions was less in the periodontitis + 1 mg/kg/day oxytocin group than in the periodontitis + saline group. Although TNF-α, IL-6, and RANKL values were lower in the periodontitis + 1 mg/kg/day oxytocin group, OPG was higher than that in the periodontitis + saline group. M-CSF, MMP-8, and MDA were lower in the oxytocin groups than in the periodontitis + saline group. Oxytocin may be an effective agent for periodontal diseases because it decreased bone resorption, oxidative stress, and inflammation in an experimental periodontitis.

Comparative Testing of Two Ligature-Induced Periodontitis Models in Rats: A Clinical, Histological and Biochemical Study

Simple Summary

This study is the first study comparing the same parameters of inflammation in two periodontal disease experimental models proposed by the literature and used in the research. The importance of the method used to induce periodontitis in animals resides in the efficacy of proposed technologies and treatments used in preclinical trials. The inflammatory markers Interleukin-1 alpha(IL-1α), Tumor Necrosis Factor-alpha (TNF-α), and high sensitive C reactive protein (hsCRP), the hematological analyses, and the histological probes showed a similar and reproducible periodontal inflammation for the molar induced periodontitis model. Ligation-induced periodontitis in rats has limitations and will never reproduce all aspects of periodontal disease in humans. The findings of this study with the complex association between clinical, biochemical, and histological aspects of the two experimental models of periodontal pathology induction in rats suggest that a similar periodontal pathology to the one we find in humans is best replicated in rats with the molar induced periodontitis model.

Abstract

Experimental animal models for studying the mechanisms of periodontitis and its links are a better alternative to in vitro studies. The aim of this study is to compare two ligature induced periodontitis models and validate the best one for further use in research. An experimental study was performed on male Wistar rats that were divided into three groups: Test 1 (n = 10), incisor ligated, Test 2 (n = 10), molar ligated, and Control (n = 10). The animals were clinically evaluated at the beginning and at the end of the experiment by recording body weight, gingival bleeding index, tooth mobility score, changes in color, and consistency of gingival tissue. Two blood samples were obtained for each animal at baseline and at the end of the experiment. The hematological parameters Interleukin-1 alpha (IL-1 α), high sensitive C Reactive Protein (hsCRP), and Tumor Necrosis Factor-alpha (TNF-α) were measured. Seven days after the induction of periodontitis, the animals were sacrificed, and samples were prepared for histological evaluation. The results of this research demonstrated that the association between clinical, histological, and biochemical parameters initiate a periodontal pathology in the molar induced model in rats while the incisor experimental model initiates only a moderate and incomplete periodontal inflammation, mainly due to mechanical irritation.

Periodontitis, chronic liver diseases, and the emerging oral-gut-liver axis

The liver carries out a wide range of functions ranging from the control of metabolites, nutrient storage, and detoxification to immunosurveillance. While inflammation is essential for the tissue remodeling and maintenance of homeostasis and normal liver physiology, constant exposure to dietary and microbial products creates a niche for potentially prolonged immune activation and unresolved inflammation in susceptible host. Failure to restrain inflammation can lead to development of chronic liver diseases characterized by fibrosis, cirrhosis and eventually liver failure. The liver maintains close interactions with numerous organs which can influence its metabolism and physiology. It is also known that oral cavity microenvironment can influence the physiological conditions of other organs and emerging evidence implicates that this could be true for the liver as well. Presence of chronic inflammation and dysbiotic microbiota is a common feature leading to clinical pathology both in periodontitis and chronic liver diseases (CLDs). In fact, known CLDs appear to have some relationship with periodontitis, which impacts the onset or progression of these conditions in a bidirectional crosstalk. In this review, we explore the emerging association between oral‐gut‐liver axis focusing on periodontitis and common CLDs including nonalcoholic fatty liver disease, chronic viral hepatitis, liver cirrhosis, and hepatocellular cancer. We highlight the immune pathways and oral microbiome interactions which can link oral cavity and liver health and offer perspectives for future research.

Polymer-Based Bone Substitutes in Periodontal Infrabony Defects: A Systematic Evaluation of Clinical Studies

Background and Objectives: The aim was to systematically review the available literature regarding the use of polymers as a bone substitute for the treatment of periodontal infrabony defect. Materials and methods: Three databases (PubMed, Scopus and Web of Science) were searched to find all relevant studies published in English from inception until September 2021 using a combination of keywords. The inclusion criteria consisted of human clinical studies which reported the use of a polymer-based bone substitute in the treatment of infrabony defects. Results: 164 studies were provided from the databases. Of these, five articles were eligible and reported favorable outcome in terms of probing depth, clinical attachment gain and defect fill at the follow-up (3 months and 6 months). Conclusions: Polymer based-bone substitutes may represent a useful alternative in treating infrabony defects. Due to the limited number of studies, more research is needed to sustain the advantages of these products.

Deciphering the toxicological role of Porphyromonas gingivalis derived endotoxins in liver diseases

Periodontitis is a most prevalent and infectious multifactorial inflammatory disease and is characterized by the progressive destruction of the tooth-supporting tissues. Porphyromonas gingivalis, a Gram‑negative oral anaerobe, mainly causes periodontitis and it is one of the most important risk factors responsible for aggravation of existing systemic diseases. Several experimental and clinical studies have shown the positive association between periodontitis and different forms of liver disease. Periodontal diseases increase the prevalence of non-alcoholic fatty liver diseases and cirrhosis. Infected periodontium and pathogens in the periodontal microenvironments release pathogen-associated molecular patterns such as peptidoglycan, lipopolysaccharides, gingipain, fimbria, bacterial DNA, etc, and damage-associated molecular patterns such as interleukins-1α, β, - 8, and galectin-3, etc. These virulence factors and cytokines enter the bloodstream, disseminate into the whole body, and induce a variety of systemic pathological effects, including liver diseases (steatosis and fibrosis). Maintaining oral hygiene by scaling and root planning significantly improves liver damage in patients with periodontitis. Dentists and physicians should have more awareness in understanding the bidirectional nature of the relationship between oral and systemic diseases. Importantly, periodontitis condition aggravates simple fatty liver into fibrotic disease and therefore, the aim of this review is to understand the possible link between periodontitis and liver diseases.

Effect of peroxisome proliferator-activated receptor-γ coactivator-1α on liver injury induced by periodontitis in rats

OBJECTIVES

To investigate the effect of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) on liver injury induced by periodontitis in rats.

METHODS

Twenty-four male Wistar rats were randomly divided into two groups: control group and periodontitis group, twelve per group. In periodontitis group, the periodontitis models were established for the maxillary first molars in rats by means of "wire ligation+vaccinationwith Porphyromonas gingivalis", the control group was inoculated with the equal volume of 2% sodium carboxymethyl cellulose in the same position, for 6 weeks. The probing depth, tooth mobility and sulcus bleeding index were detected. Hematoxylin-eosin (HE) staining was used to observe the pathological changes of liver tissues in rats. The quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) were used to detect the gene and protein expression levels of PGC-1α, nuclear factor erythroid 2-related factor 2 (Nrf2) and mitochondrial transcription factor A (TFAM) in liver tissues of rats.

RESULTS

The probing depth, tooth mobility and sulcus bleeding index in periodontitis group were significantly higher than that in control group. HE staining showed in periodontitis group, hepatic cords ranged disorderly and there were vacuoles in cells and inflammatory cells infiltrated in liver tissues of rats, and there was no obvious abnormality in control group. The qRT-PCR results showed that the mRNA expression levels of Pgc-1α, Nrf2 and Tfam in liver tissues of rats in periodontitis group were lower obviously than that in control group. IHC results showed that the protein expression level of PGC-1α in liver tissues of rats in periodontitis group was decreased significantly than that in control group.

CONCLUSIONS

PGC-1α may be involved in the process of periodontitis-induced liver injury in rats.

Periodontal disease-related nonalcoholic fatty liver disease and nonalcoholic steatohepatitis: An emerging concept of oral-liver axis

Periodontal disease, a chronic inflammatory disease of the periodontal tissues, is not only a major cause of tooth loss, but it is also known to exacerbate/be associated with various metabolic disorders, such as obesity, diabetes, dyslipidemia, and cardiovascular disease. Recently, growing evidence has suggested that periodontal disease has adverse effects on the pathophysiology of liver disease. In particular, nonalcoholic fatty liver disease, a hepatic manifestation of metabolic syndrome, has been associated with periodontal disease. Nonalcoholic fatty liver disease is characterized by hepatic fat deposition in the absence of a habitual drinking history, viral infections, or autoimmune diseases. A subset of nonalcoholic fatty liver diseases can develop into more severe and progressive forms, namely nonalcoholic steatohepatitis. The latter can lead to cirrhosis and hepatocellular carcinoma, which are end‐stage liver diseases. Extensive research has provided plausible mechanisms to explain how periodontal disease can negatively affect nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, namely via hematogenous or enteral routes. During periodontitis, the liver is under constant exposure to various pathogenic factors that diffuse systemically from the oral cavity, such as bacteria and their by‐products, inflammatory cytokines, and reactive oxygen species, and these can be involved in disease promotion of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. Also, gut microbiome dysbiosis induced by enteral translocation of periodontopathic bacteria may impair gut wall barrier function and promote the transfer of hepatotoxins and enterobacteria to the liver through the enterohepatic circulation. Moreover, in a population with metabolic syndrome, the interaction between periodontitis and systemic conditions related to insulin resistance further strengthens the association with nonalcoholic fatty liver disease. However, most of the pathologic links between periodontitis and nonalcoholic fatty liver disease in humans are provided by epidemiologic observational studies, with the causal relationship not yet being established. Several systematic and meta‐analysis studies also show conflicting results. In addition, the effect of periodontal treatment on nonalcoholic fatty liver disease has hardly been studied. Despite these limitations, the global burden of periodontal disease combined with the recent nonalcoholic fatty liver disease epidemic has important clinical and public health implications. Emerging evidence suggests an association between periodontal disease and liver diseases, and thus we propose the term periodontal disease–related nonalcoholic fatty liver disease or periodontal disease–related nonalcoholic steatohepatitis. Continued efforts in this area will pave the way for new diagnostic and therapeutic approaches based on a periodontologic viewpoint to address this life‐threatening liver disease.

Protective Effects of Taraxacum officinale L. (Dandelion) Root Extract in Experimental Acute on Chronic Liver Failure

BACKGROUND

Taraxacum officinale (TO) or dandelion has been frequently used to prevent or treat different liver diseases because of its rich composition in phytochemicals with demonstrated effect against hepatic injuries. This study aimed to investigate the possible preventing effect of ethanolic TO root extract (TOERE) on a rat experimental acute on chronic liver failure (ACLF) model.

METHODS

Chronic liver failure (CLF) was induced by human serum albumin, and ACLF was induced in CLF by D-galactosamine and lipopolysaccharide (D-Gal-LPS). Five groups (n = 5) of male Wistar rats (200-250 g) were used: ACLF, ACLF-silymarin (200 mg/kg b.w./day), three ACLF-TO administered in three doses (200 mg, 100 mg, 50 mg/kg b.w./day).

RESULTS

The in vivo results showed that treatment with TOERE administered in three chosen doses before ACLF induction reduced serum liver injury markers (AST, ALT, ALP, GGT, total bilirubin), renal tests (creatinine, urea), and oxidative stress tests (TOS, OSI, MDA, NO, 3NT). Histopathologically, TOERE diminished the level of liver tissue injury and 3NT immunoexpression.

CONCLUSIONS

This paper indicated oxidative stress reduction as possible mechanisms for the hepatoprotective effect of TOERE in ACLF and provided evidence for the preventive treatment.

Association between periodontitis and fibrotic progression of non-alcoholic fatty liver among Japanese adults

AIM

Non-alcoholic fatty liver (NAFL) is known to develop into liver fibrosis, which increases the risk of liver cirrhosis and liver cancer. The association between periodontal condition and fibrotic progression of NAFL is unclear. This study aimed to clarify this longitudinal association.

MATERIALS AND METHODS

Among 4812 participants aged 35-64 years undergoing annual health check-ups between 2003 and 2004, and follow-up 5 years later, 392 participants were diagnosed with NAFL. After excluding participants with liver fibrosis at baseline, 341 participants were followed up for 5 years. NAFL disease fibrosis score of ≥-1.455 was used to evaluate the probability of the presence of liver fibrosis.

RESULTS

During the follow-up period, 10.6% of participants progressed to liver fibrosis. A higher clinical attachment level (CAL) tended to be associated with the incidence of liver fibrosis in the logistic regression analysis (odds ratio [OR] 1.82, 95% confidence interval [CI], 0.94-3.49, p = .074). The stratified analysis by obesity revealed a significant association with higher CAL in obese participants (OR 2.87, 95% CI, 1.23-6.69, p = .015), but not in non-obese participants.

CONCLUSION

Higher CAL was associated with an increased probability of liver fibrosis in obese adults with NAFL.

Ginsenoside Rb3 Inhibits Pro-Inflammatory Cytokines via MAPK/AKT/NF-κB Pathways and Attenuates Rat Alveolar Bone Resorption in Response to Porphyromonas gingivalis LPS

Conventional treatments for chronic periodontitis are less effective in controlling inflammation and often relapse. Therefore, it is necessary to explore an immunomodulatory medication as an adjuvant. Ginsenoside Rb3 (Rb3), one of the most abundant active components of ginseng, has been found to possess anti-inflammatory and immunomodulatory properties. Here, we detected the anti-inflammatory effect of Rb3 on Porphyromonas gingivalis LPS-stimulated human periodontal ligament cells and experimental periodontitis rats for the first time. We found that the expression of pro-inflammatory mediators, including IL-1β, IL-6 and IL-8, upregulated by lipopolysaccharide (LPS) stimulation was remarkably downregulated by Rb3 treatment in a dose-dependent manner at both transcriptional and translational levels. Network pharmacological analysis of Rb3 showed that the mitogen-activated protein kinase (MAPK) signaling pathway had the highest richness and that p38, JNK, and ERK molecules were potential targets of Rb3 in humans. Western blot analysis revealed that Rb3 significantly suppressed the phosphorylation of p38 MAPK and p65 NF-κB, as well as decreased the expression of total AKT. In experimental periodontitis rat models, reductions in alveolar bone resorption and osteoclast generation were observed in the Rb3 treatment group. Thus, we can conclude that Rb3 ameliorated Porphyromonas gingivalis LPS-induced inflammation by inhibiting the MAPK/AKT/NF-κB signaling pathways and attenuated alveolar bone resorption in experimental periodontitis rats.

The role of TLR4/MyD88/NF-κB pathway in periodontitis-induced liver inflammation of rats

OBJECTIVES

The aim of this study was to clarify the immune mechanism of hepatic injury induced by periodontitis using a rat model.

METHODS

Twenty-four SPF male Wistar rats were randomly divided into two groups: control group (CG) and periodontitis group (PG). In order to induce experimental periodontitis, we tied the wire ligature around bilateral maxillary first molar of rats. After 8 weeks, the following indicators were valued: gingival index, tooth mobility, probing pocket depth; indexes about oxidative stress and circulating biomarkers; bone retraction by micro-CT analysis; Toll-like receptor 4 (TLR4), myeloid differential protein-88 (MyD88), and nuclear factor kappa B (NF-κB) by qRT-PCR and Western blotting; tumor necrosis factor α (TNF-α), and interleukin-6 (IL-6) by qRT-PCR and immunohistochemical staining; inflammation of periodontal and hepatic tissues by histopathological observation.

RESULTS

Periodontal indicators and micro-CT results showed the raised levels of inflammatory response and bone retraction in PG compared with CG. The mRNA and protein levels of TLR4, MyD88, NF-κB, TNF-α, and IL-6 have indicated high values in PG versus CG. Histopathological analysis revealed a correlation between periodontitis and hepatic injury.

CONCLUSION

TLR4/MyD88/NF-κB pathway may play a role in periodontitis-induced liver inflammation of rats.

Detection of Serum miRNAs Affecting Liver Apoptosis in a Periodontitis Rat Model

BACKGROUND/AIM

miRNA molecules have been attracting attention as genetic modifiers between organs. We examined the relationship between serum miRNA and targeted liver mRNA profiles in a periodontitis rat model, and the influence of periodontitis on the liver.

MATERIALS AND METHODS

Male Wistar rats (n=16, 8 weeks old) were randomly divided into two groups (8 rats each): control and periodontitis (ligature placement for 4 weeks). Serum miRNA and liver mRNA profiles were compared.

RESULTS

Periodontal destruction and hepatocyte apoptosis were induced in the periodontitis group. Microarray analysis indicated that 52 serum miRNAs and 33 liver mRNAs were expressed with a >1.5-fold change (FC) and a >2.0-FC (p<0.05), respectively, between the two groups. From the miRNA target genes, 12 genes equivalented to liver mRNAs with a >2.0-FC, among which, Hyou1, Chac1, and Bloc1s3 have apoptotic functions in our model. miRNAs upstream of these 3 mRNAs are miR-3591, miR-181a-2-3p and miR-6321.

CONCLUSION

miR-3591, miR-181a-2-3p and miR-6321 induced hepatocyte apoptosis in our periodontitis rat model.