Effect of diabetes on collagen metabolism and hypoxia in human gingival tissue: a stereological, histopathological, and immunohistochemical study

Essential role of the metabolite α-ketoglutarate in bone tissue and bone-related diseases

Bone metabolism in bone tissue is constantly maintained in a state of dynamic equilibrium. The mass of bone and joint tissues is determined by both bone formation and bone resorption. It is hypothesized that disrupted metabolic balance leads to osteoporosis, osteoarthritis, rheumatoid arthritis, and bone tumors. Such disruptions often manifest as either a reduction or abnormality in bone mass and are frequently accompanied by pathological changes such as inflammation, fractures, and pain. α-Ketoglutarate (α-KG) serves as a pivotal intermediate in various metabolic pathways in mammals, significantly contributing to cellular energy metabolism, amino acid metabolism, and other physiological processes. α-KG may be a therapeutic target for a variety of bone-related diseases, such as osteoporosis, osteoarthritis, and rheumatoid arthritis, because of its role in maintaining the metabolic balance of bone. After the application of α-KG, bone loss and inflammation in bone tissue are alleviated. This review focuses on the regulatory effects of α-KG on various cells in bone and joint tissues. Owing to the regulatory effect of α-KG on the balance of bone metabolism, the application of α-KG in the treatment of osteoporosis, osteoarthritis, rheumatoid arthritis, bone tumors, and other bone tissue diseases has been clarified.

Immunopathogenesis and immunotherapy of diabetes-associated periodontitis

OBJECTIVES

This paper aims to review the immunopathogenesis of Diabetes-associated periodontitis (DPD) and to propose a description of the research progress of drugs with potential clinical value from an immunotherapeutic perspective.

MATERIALS AND METHODS

A comprehensive literature search was conducted in PubMed, MEDLINE, Embase, Web of Science, Scopus and the Cochrane Library. Inclusion criteria were studies on the association between diabetes and periodontitis using the Boolean operator "AND" for association between diabetes and periodontitis, with no time or language restrictions. Search terms included diabetes mellitus, periodontitis, immunopathogenesis, specific immunity, non-specific immunity, flora, estrogen, pharmacological treatment, immunotherapy.

RESULTS

Alterations in the subgingival flora environment in a hyperglycemic environment elicit an immune response. Overactivity/suppression of nonspecific immune cells and impaired cellular defenses trigger specific immune responses. Epigenetics as well as female hormones also play a role. There is already a small amount of clinical evidence for the role of metronidazole, subantimicrobial doses of doxycycline, minocycline hydrochloride, and metformin in the treatment of DPD. Some preclinical studies have also accumulated experimental evidence for the improved effects of vitamin D3 and other drugs on DPD.

CONCLUSIONS

The development of diabetic periodontitis is immunologically linked to a state of immune imbalance and therefore holds great promise for the use of immunotherapeutic drugs.

CLINICAL SIGNIFICANCE

Immunotherapy with drugs along with periodontal nonsurgical treatment could provide ideas for DPD treatment based on the immunopathogenesis of DPD.

Direct impact of psoriasis on gingival crevicular fluid levels of VEGF-A in periodontitis patients: a mediation analysis

Introduction

Emerging evidence suggests that psoriasis and periodontitis are linked via systemic inflammation. However, the role of angiogenesis as an additional connecting mechanism between these diseases remains unclear.

Methods

This case control study explored the effect of psoriasis on the gingival crevicular fluid (GCF) levels of vascular endothelial growth factor A (VEGF-A) in patients with different stages of periodontitis. Thirty-one patients with psoriasis (P) and thirty healthy controls (C) underwent physical and intraoral evaluations, with diagnoses confirmed by dermatologists and periodontists. GCF VEGF-A was measured using a multiplex-bead immunoassay. Statistical analyses included Fisher exact tests, Student's T-tests, linear regression models, and mediation analyses.

Results

Psoriasis patients had significantly lower GCF VEGF-A levels compared to controls (p=0.008). Psoriasis was negatively associated with GCF VEGF-A (p=0.006), while severe periodontitis was positively associated with GCF VEGF-A levels, regardless of tobacco use (p=0.027). Further analyses revealed that severe periodontitis significantly increased GCF VEGF-A levels only in the C group (p=0.038), but not in psoriasis patients (p>0.610). Mediation analyses confirmed a significant direct and total effect of psoriasis on GCF VEGF-A (p>0.002), with no significant indirect effect through periodontitis (p=0.699).

Discussion

Psoriasis and severe periodontitis are associated with GCF levels of VEGF-A in opposite and independent ways. In subjects with psoriasis, the impact of the dermatosis is direct with no mediation from periodontitis.

The Efficacy of Topical or Systemic Antibiotics as Adjuvants to Non-Surgical Periodontal Treatment in Diabetic Patients: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Background: Periodontitis and diabetes mellitus (DM) exhibit a bidirectional relationship and are globally significant systemic chronic conditions. The utilization of antibiotics alongside non-surgical periodontal treatment (NSPT) has been a subject of investigation in numerous clinical studies involving human subjects. Thus, the objective of this systematic review is to address the following question: "What is the efficacy of scaling and root planing (SRP) associated with antimicrobials in patients with type 2 DM and periodontitis?". Methods: A systematic review of the literature was conducted encompassing databases such as MEDLINE/PubMed, Scopus, and Web of Science up to July 2024. Additionally, alerts were configured to capture studies published from the initial search until manuscript submission. Randomized clinical trials assessing clinical periodontal parameters in DM patients undergoing SRP and receiving either topical or systemic antibiotics were compared against a control group (SRP only). Two investigators independently screened articles, extracted data, and evaluated their quality. The selection process, study characteristics, risk of bias, impact of antibiotics on clinical parameters, and certainty of evidence were elucidated in both textual and tabular formats. Meta-analysis was performed separately with forest plots generated for treatment modalities, period of evaluation, and type of antibiotics used. Results: Following the analysis of abstracts and full articles, a total of 30 randomized clinical trials were incorporated into this review, comprising 9 studies on the association of topical antibiotics and 21 studies on systemic antibiotic administration. The principal periodontal parameters assessed included probing pocket depth (PPD), clinical attachment level (CAL), plaque index (PI), and bleeding on probing (BoP). Conclusions: Analysis of the results led to the conclusion that adjunctive periodontal treatment with either topical or systemic antibiotics confers subtle clinical benefits. Nevertheless, owing to the heightened emergence of resistant bacteria and potential side effects, the use of antibiotic therapy in periodontal treatment should be judiciously administered.

Vascular Endothelial Growth Factor A serum levels and common gene polymorphisms in generalized periodontitis affected patients

OBJECTIVE

To evaluate and compare the associations of VEGFA serum levels and SNPs (rs1570360, rs699947, rs3025033, and rs2146323) with periodontitis in study participants grouped by gender.

METHODS

The study enrolled 261 patients with periodontitis and 441 healthy controls as a reference group. Patients underwent periodontal examination and radiographic analysis to confirm the periodontitis diagnosis. Blood samples were collected, and the DNA salting-out method was used for DNA extraction from peripheral venous blood. Genotyping of VEGFA (rs1570360, rs699947, rs3025033, and rs2146323) was performed using real-time polymerase chain reaction (RT-PCR) and serum level analysis was done for 80 individuals - 40 periodontitis-affected patients and 40 reference group subjects.

RESULTS

The analysis of VEGFA (rs1570360, rs699947, rs3025033, and rs2146323) showed that the rs3025033 GG genotype was less frequent in the periodontitis group than in the reference group (1.6% vs. 5.7%,p = 0.008). VEGFA serum levels were not statistically significantly different between periodontitis patients and reference group subjects (554.29 (522.38) ng/ml vs. 581.32 (348.16) ng/ml, p = 0.786). Individuals carrying rs1570360, rs699947, rs3025033, and rs2146323 haplotype A-A-G-A had decreased risks of periodontitis, while rare haplotype of VEGFA (rs1570360, rs699947, rs3025033, and rs2146323) was associated with increased odds of periodontitis (OR= 0.42; 95% CI: 0.20-0.85; p < 0.017; OR= 4.08; 95% CI: 1.86-8.94; p < 0.0001, respectively).

CONCLUSION

The rs3025033 GG genotype and the rs1570360, rs699947, rs3025033, and rs2146323 A-A-G-A haplotypes may play a protective role in the development of periodontitis, but a less common haplotype of the same VEGFA polymorphism may be associated with the risk of developing periodontitis.

Enzyme-Responsive Nanoparticles for Dexamethasone Targeted Delivery to Treat Inflammation in Diabetes

Diabetes is a global epidemic accompanied by impaired wound healing and increased risk of persistent infections and resistance to standard treatments. Therefore, there is an immense need to develop novel methods to specifically target therapeutics to affected tissues and improve treatment efficacy. This study aims to use enzyme-responsive nanoparticles for the targeted delivery of an anti-inflammatory drug, dexamethasone, to treat inflammation in diabetes. These nanoparticles are assembled from fluorescently-labeled, dexamethasone-loaded peptide-polymer amphiphiles. The nanoparticles are injected in vivo, adjacent to labeled collagen membranes sub-periosteally implanted on the calvaria of diabetic rats. Following their implantation, collagen membrane resorption is linked to inflammation, especially in hyperglycemic individuals. The nanoparticles show strong and prolonged accumulation in inflamed tissue after undergoing a morphological switch into microscale aggregates. Significantly higher remaining collagen membrane area and less inflammatory cell infiltration are observed in responsive nanoparticles-treated rats, compared to control groups injected with free dexamethasone and non-responsive nanoparticles. These factors indicate improved therapeutic efficacy in inflammation reduction. These results demonstrate the potential use of enzyme-responsive nanoparticles as targeted delivery vehicles for the treatment of diabetic and other inflammatory wounds.

Addition of Resolvins D1 or E1 to Collagen Membranes Mitigates Their Resorption in Diabetic Rats

Uncontrolled diabetes is characterized by aberrant inflammatory reactions and increased collagenolysis. We have reported that it accelerates the degradation of implanted collagen membranes (CM), thus compromising their function in regenerative procedures. In recent years, a group of physiological anti-inflammatory agents called specialized pro-resolving lipid mediators (SPMs) have been tested as a treatment for various inflammatory conditions, either systemically or locally, via medical devices. Yet, no study has tested their effect on the fate of the biodegradable material itself. Here, we measured the in vitro release over time of 100 or 800 ng resolvin D1 (RvD1) incorporated into CM discs. In vivo, diabetes was induced in rats with streptozotocin, while buffer-injected (normoglycemic) rats served as controls. Resolvins (100 or 800 ng of RvD1 or RvE1) were added to biotin-labeled CM discs, which were implanted sub-periosteally over the calvaria of rats. Membrane thickness, density, and uniformity were determined by quantitative histology after 3 weeks. In vitro, significant amounts of RvD1 were released over 1-8 days, depending on the amount loaded. In vivo, CMs from diabetic animals were thinner, more porous, and more variable in thickness and density. The addition of RvD1 or RvE1 improved their regularity, increased their density, and reduced their invasion by the host tissue significantly. We conclude that addition of resolvins to biodegradable medical devices can protect them from excessive degradation in systemic conditions characterized by high degree of collagenolysis.

The Bidirectional Relationship between Periodontal Disease and Diabetes Mellitus-A Review

Periodontitis is a chronic inflammatory disease caused by the presence of a bacterial biofilm known as dental plaque. This biofilm affects the supporting apparatus of the teeth, especially the periodontal ligaments and the bone surrounding the teeth. Periodontal disease and diabetes seem to be interrelated and in a bidirectional relationship, and have been increasingly studied in recent decades. For example, diabetes mellitus has a detrimental effect on periodontal disease, increasing its prevalence, extent, and severity. In turn, periodontitis negatively affects glycemic control and the course of diabetes. This review aims to present the most recently discovered factors that contribute to the pathogenesis, therapy, and prophylaxis of these two diseases. Specifically, the article focuses on microvascular complications, oral microbiota, pro- and anti-inflammatory factors in diabetes, and periodontal disease. As presented in this review, these two diseases require specific/ complementary therapeutic solutions when they occur in association, with new clinical trials and epidemiological research being necessary for better control of this interdependent pathogenic topic.

Novel Insight into the Mechanisms of the Bidirectional Relationship between Diabetes and Periodontitis

Periodontitis and diabetes are two major global health problems despite their prevalence being significantly underreported and underestimated. Both epidemiological and intervention studies show a bidirectional relationship between periodontitis and diabetes. The hypothesis of a potential causal link between the two diseases is corroborated by recent studies in experimental animals that identified mechanisms whereby periodontitis and diabetes can adversely affect each other. Herein, we will review clinical data on the existence of a two-way relationship between periodontitis and diabetes and discuss possible mechanistic interactions in both directions, focusing in particular on new data highlighting the importance of the host response. Moreover, we will address the hypothesis that trained immunity may represent the unifying mechanism explaining the intertwined association between diabetes and periodontitis. Achieving a better mechanistic insight on clustering of infectious, inflammatory, and metabolic diseases may provide new therapeutic options to reduce the risk of diabetes and diabetes-associated comorbidities.

Herbal Infusions as a Valuable Functional Food

Herbal infusions are an underestimated and easy to intake a source of biologically active natural compounds (polyphenols), which, in the dissolved form, are more easily absorbed. Therefore, this study aimed to assess the potential of herbal infusions as a functional food to reduce postprandial hyperglycemia (inhibition of α-amylase and α-glucosidase) and to reduce the effects of increased blood glucose level (antioxidant effect-DPPH, CUPRAC, and Fe²⁺ chelating assays, as well as anti-inflammatory activity-inhibition of collagenase). We showed that polyphenols are present in the examined aqueous herbal infusions (including chlorogenic and gallic acids). Subsequently, our research has shown that herbal infusions containing cinnamon bark, mulberry leaves, and blackberry fruits most strongly inhibit glucose release from complex carbohydrates, and that all herbal infusions can, to different degrees, reduce the effects of elevated blood sugar. In conclusion, infusions prepared from herbal blends could be recommended to prevent type II diabetes.

Quercetin Decreased Alveolar Bone Loss and Apoptosis in Experimentally Induced Periodontitis Model in Wistar Rats

BACKGROUND

Quercetin is a flavonoid which has potent anti-inflammatory, antibacterial, and antioxidant effect. Purpose of this study was to evaluate effects of quercetin on alveolar bone loss and histopathological changes in ligature-induced periodontitis in rats.

METHODS

Wistar rats were divided into four experimental groups: non-ligated control (C, n=8) group; periodontitis (P, n=8) group; ligature and low dose quercetin group (75 mg/kg/day quercetin, Q75 group, n=8); ligature and high dose quercetin group (150 mg/kg/day quercetin, Q150 group, n=8). Silk ligatures were placed at gingival margin of lower first molars of mandibular right quadrant. Study duration was 15 days, and animals were sacrificed end of this period. Changes in alveolar bone levels were clinically measured and tissues were immunohistochemically examined, matrix metalloproteinase 8 (MMP 8), inducible nitric oxide synthase (iNOS), tissue inhibitor of metalloproteinase 1 (TIMP 1), Cysteine-aspartic proteases 3 (Caspase 3), and tartrate-resistant acid phosphatase (TRAP) positive osteoclast cells, osteoblast, and neutrophil counts were also determined.

RESULTS AND DISCUSSION

Alveolar bone loss was highest in P group, and differences among P, Q75, and Q150 groups were significant. Both doses of quercetin decreased TRAP+ osteoclast cells and increased osteoblast cells. Inflammation in P group was also higher than those of C, Q75, and Q150 groups indicating anti-inflammatory effect of quercetin. iNOS, MMP-8, and caspase-3 levels were highest, and TIMP-1 expression was lowest in P group; differences were statistically significant.

CONCLUSION

Within limits of this study, it can be suggested that quercetin administration may reduce alveolar bone loss by increasing osteoblastic activity, decreasing osteoclastic activity, apoptosis, and inflammation in an experimental model of periodontitis.

VEGF as a potential molecular target in periodontitis: a meta-analysis and microarray data validation

BACKGROUND

Anti-vascular endothelial growth factor (VEGF) has been used as a therapeutic drug for the treatment of some human diseases. However, no systematic evidence is performed for assessing the role of VEGF in periodontitis. We carried out a comprehensive analysis to explore the role of VEGF in patients with periodontitis.

METHODS

Multiple databases were searched for eligible studies. The pooled standardized mean difference (SMD) and odds ratio (OR) with the corresponding 95% confidence interval (CI) were applied to evaluate the effect sizes. Clinical data validation from microarray analysis was used. Pathway and process enrichment analysis were also investigated.

RESULTS

Finally, 16 studies were included in this analysis. Overall, there was a significantly higher level of VEGF expression in periodontitis than in healthy control groups (OR = 16.64, 95% CI = 6.01-46.06, P < 0.001; SMD = 2.25, 95% CI = 1.25-3.24, P < 0.001). Subgroup analysis of ethnicity showed that VEGF expression was still correlated with periodontitis in the Asian and European populations. No correlation was observed between VEGF expression and age, gender, and pathological type. A large clinical sample data (427 periodontitis patients and 136 healthy controls) further validated that VEGF expression was higher in periodontitis than in healthy control groups (P = 0.023). VEGF was involved in many functions such as blood vessel development, response to growth factor, cell proliferation, and cell adhesion.

CONCLUSIONS

High levels of VEGF were credible implications for the development of periodontitis. Anti-VEGF therapy may be valuable for the treatment of periodontitis in clinical management.

Hyaluronic acid with antioxidants improve wound healing in rats

Hyaluronic acid (HA) is found in connective tissue and participates in wound healing. We investigated the efficacy of a HA gel (2% hyaluronic acid; 1% antioxidants, coenzyme Q10 and vitamin E; and 5% benzocaine) on healing of palatal wounds in rats. We established two groups of rats: a control group treated with vehicle and an HA group treated with HA gel. The control group was divided into five subgroups and the HA group was divided into four subgroups according to the day on which animals were sacrificed. Wounds were created by elevating 5 mm diameter full thickness flaps. Healed and unhealed wound areas were measured using photographs. Transforming growth factor (TGF)-β, insulin-like growth factor (IGF), and collagen I and III expressions were determined using immunohistochemistry. The number of fibroblasts increased and inflammatory cells decreased from day 0 to 21 in both groups. The HA group exhibited more fibroblasts by day 7 compared to controls; (TGF)-β and IGF levels were similar between HA and control groups. HA groups exhibited fewer inflammatory cells than controls on days 3 and 7. We found significant differences in TGF-β and IGF levels among HA groups between days 3 and 21, and among control groups between days 0 and 21. Collagen I and III levels were greater for the day 3 HA group compared to controls. We observed improved wound healing in HA treated rats within 7 days.

Histological evaluation of peri-implant mucosal and gingival tissues in peri-implantitis, peri-implant mucositis and periodontitis patients: a cross-sectional clinical study

Objective: Aim of present study was to evaluate gingival tissue samples obtained from healthy and diseased sites of teeth and dental implants in terms of hypoxia and collagenase activity.Methods: Four study groups were created as Group-1; healthy individuals (H), Group-2; periodontitis patients with stage 3 grade B (P), Group-3; patients with peri-implant mucositis. Group-4; patients with peri-implantitis (P-IMP). Plaque index (PI), gingival index (GI) and probing pocket depth (PPD) were recorded. Gingival and peri-implant mucosal biopsies were obtained. Fibroblast and inflammatory cells were counted. Hypoxia-inducible factor (HIF)-1α, prolyl hydroxylase (PH), matrix metalloproteinase (MMP)-8, tissue inhibitor of MMPs (TIMP)-1, cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) levels were determined via immunohistochemistry.Results: Healthy controls had highest fibroblast cell counts and lowest inflammatory cell counts compared to other groups. Peri-implantitis and periodontitis samples had similar fibroblast and inflammatory cell counts, while peri-implant mucositis had higher fibroblast cells and lowered inflammatory cells compared to periodontitis and peri-implantitis samples. HIF-1α, COX-2 and iNOS levels were lowest in healthy controls and increased in other groups. Peri-implant mucositis samples had significantly lower expressions of HIF-1α, COX-2 and iNOS compared to peri-implantitis and periodontitis groups. PH expressions were lower in periodontitis and peri-implantitis groups compared to healthy controls and peri-implant mucositis groups. MMP-8 levels were lower in healthy group compared to other groups while levels were similar in periodontitis, peri-implant mucositis and peri-implantitis groups. TIMP levels were similar in groups.Conclusion: Periodontitis, peri-implantitis, and peri-implant mucositis samples exhibited higher inflammation and lower fibroblast cell counts and tend to have increased tissue collagenase activity, hypoxia and inflammation compared to healthy samples.

Accelerated degradation of collagen membranes in type 1 diabetic rats is associated with increased expression and production of several inflammatory molecules

BACKGROUND

Membrane durability is critical for regenerative procedures. We reported previously that type 1-like diabetes in rats accelerates the degradation of collagen membranes and we tested here whether this is associated with increased local production of inflammatory molecules as part of a diabetes-induced chronic inflammation around and within the membranes.

METHODS

Collagen membrane discs were implanted under the scalp in diabetic (streptozotocin-induced) and control rats, which were sacrificed after 2 or 3 weeks. Total RNA and proteins were isolated from the membrane and its surrounding tissues and the expression and production of six inflammatory molecules (interleukin-6 [IL-6], tumor necrosis factor alpha [TNFα], matrix metalloproteinase [MMP]-9, macrophage migration inhibitory factor [MIF], MIP-1α, and MIP-2α) was measured using real-time PCR and western blotting, respectively. Minimal histological analysis of the membranes was conducted to conform to previous studies.

RESULTS

Hyperglycemia resulted in reduced membrane thickness (by 10% to 25%) and increased mononuclear infiltrate inside the membrane. mRNA and protein levels of IL-6, TNFα, and MMP-9 were elevated in diabetic rats both 2 and 3 weeks post-surgery. The levels (both mRNA and protein) of MIF were increased at 2 weeks post-surgery and those of MIP-1α and MIP-2α at 3 weeks. There was a very good match in the temporal changes of all examined genes between the mRNA and protein levels.

CONCLUSIONS

Elevated local production of inflammatory cytokines and MMPs, together with apparent mononuclear infiltrate and increased collagenolysis confirm that hyperglycemia leads to a chronic inflammation in and around the implanted collagen membranes, which reduces membrane longevity.

Hypoxia and collagen crosslinking in the healthy and affected sites of periodontitis patients

Present study suggests that diseased sites of periodontitis with stage 3 grade B and C had decreased fibroblast cell density, hypoxia-inducible factor (HIF) and vascular endothelial growth factor (VEGF) expressions while increased inflammatory cell counts compared to both healthy sites of the periodontitis patients and healthy controls. Collagen maturation enzymes also decreased in the diseased sites. Objective: The present study aimed at determining markers of hypoxia and collagen crosslinking in healthy and diseased gingiva from healthy individuals and periodontitis patients. Methods: Group-1; healthy individuals, Group-2; healthy sites of periodontitis patients-stage 3 grade B, (H-GradeB) Group-3; diseased sites of periodontitis patients-stage 3 grade B, (D-GradeB). Group-4; healthy sites of periodontitis patients-stage 3 grade C, (H-GradeC). Group-5; diseased sites of periodontitis patients-stage 3 grade C, (D-GradeC). Plaque index (PI), gingival index (GI) and clinical attachment levels (CALs) were recorded. Gingival biopsies were obtained. Fibroblast and inflammatory cells were counted. HIF-1α, prolyl hydroxylase (PH), VEGF, lysyl oxidase (LOX) and lysyl hydroxylase (LH) levels were determined via immunohistochemistry. Results: Fibroblast cell counts were lower in D-GradeC and D-GradeB than other groups. C group had highest fibroblast cell counts. Inflammatory cell counts were highest in the D-GradeC and lowest in C group. HIF-1α levels were highest in C group and decreased in diseased sites. Lowest value was observed in D-GradeC group. VEGF, PH, and LH levels were higher in the control group compared to other groups. LOX levels were similar in the groups except for D-GradeC. LOX levels were similar in the groups except for D-GradeC which is significantly lower than those of the control group and healthy sites. Conclusions: The results revealed that diseased sites of periodontitis patients had decreased fibroblast cells, HIF and VEGF expressions while increased inflammatory cells. Collagen crosslinking tend to decrease with disease regardless of stage and grade of disease.