Polymorphism of salivary proteins and risk of periodontal diseases: A systematic review and meta-analysis of clinical studies

OBJECTIVES

The present systematic review and meta-analysis aimed to assess the association between salivary protein polymorphisms and the risk of periodontal diseases (PD).

DATA

The review incorporated cross-sectional, case-control, retrospective/prospective cohort, and randomized controlled trials assessing the influence of salivary protein polymorphisms on the risk of PD development were included in this review.

SOURCES

A thorough literature search was conducted across electronic databases, namely PubMed, Scopus, Embase, and Web of Science, without any restrictions on publication language and year.

STUDY SELECTION

A total of 168 studies were identified, of which 19 were eligible for inclusion. The risk of bias (RoB) assessment of the included studies was conducted at the methodological level.

RESULTS

A total of 16 studies were included. Polymorphism in the gene encoding TNF-α was found to be protective against gingivitis, while those encoding IL-1α and IL-1β were associated with developing gingivitis. Of the 42 proteins investigated, various gene polymorphisms were identified as protective or risk factors for periodontitis. Protective genes include CFH, DNMT1, OPRM1, and TLR9. Conversely, certain salivary protein genes (e.g., CRP, ERN1, FAM5C, IDH2, LTA, TET2, MPA, NLRP3, TLR4) were associated with periodontitis risk. Notably, IL6, MMP9, and MUC7 genes showed no association with PD, while MMP13 was linked to early implant loss. Overall, the meta-analysis found a statistically significant association between salivary proteins' polymorphisms and risk of PD.

CONCLUSIONS

Salivary protein polymorphisms significantly influence PD, revealing protective and risk-associated genotypes. Despite limitations, findings suggest therapeutic targets, emphasizing the complex genetics-periodontal health interplay.

CLINICAL SIGNIFICANCE

This study unveils salivary protein polymorphisms as pivotal factors in PD. Protective genes including CFH and TLR9, and risk-associated genes including CRP and TLR4, indicate a genetic basis for PD susceptibility.

A biomaterial-based therapy for lower limb ischemia using Sr/Si bioactive hydrogel that inhibits skeletal muscle necrosis and enhances angiogenesis

Muscle necrosis and angiogenesis are two major challenges in the treatment of lower-limb ischemic diseases. In this study, a triple-functional Sr/Si-containing bioceramic/alginate composite hydrogel with simultaneous bioactivity in enhancing angiogenesis, regulating inflammation, and inhibiting muscle necrosis was designed to treat lower-limb ischemic diseases. In particular, sodium alginate, calcium silicate and strontium carbonate were used to prepare injectable hydrogels, which was gelled within 10 min. More importantly, this composite hydrogel sustainedly releases bioactive Sr²⁺ and SiO₃ ^2- ions within 28 days. The biological activity of the bioactive ions released from the hydrogels was verified on HUVECs, SMCs, C2C12 and Raw 264.7 cells in vitro, and the therapeutic effect of the hydrogel was confirmed using C57BL/6 mouse model of femoral artery ligation in vivo. The results showed that the composite hydrogel stimulated angiogenesis, developed new collateral capillaries, and re-established the blood supply. In addition, the bioactive hydrogel directly promoted the expression of muscle-regulating factors (MyoG and MyoD) to protect skeletal muscle from necrosis, inhibited M1 polarization, and promoted M2 polarization of macrophages to reduce inflammation, thereby protecting skeletal muscle cells and indirectly promoting vascularization. Our results indicate that these bioceramic/alginate composite bioactive hydrogels are effective biomaterials for treating hindlimb ischemia and suggest that biomaterial-based approaches may have remarkable potential in treating ischemic diseases.

Human Umbilical Cord Mesenchymal Stem Cells: Current Literature and Role in Periodontal Regeneration

Periodontal disease can cause irreversible damage to tooth-supporting tissues such as the root cementum, periodontal ligament, and alveolar bone, eventually leading to tooth loss. While standard periodontal treatments are usually helpful in reducing disease progression, they cannot repair or replace lost periodontal tissue. Periodontal regeneration has been demonstrated to be beneficial in treating intraosseous and furcation defects to varied degrees. Cell-based treatment for periodontal regeneration will become more efficient and predictable as tissue engineering and progenitor cell biology advance, surpassing the limitations of present therapeutic techniques. Stem cells are undifferentiated cells with the ability to self-renew and differentiate into several cell types when stimulated. Mesenchymal stem cells (MSCs) have been tested for periodontal regeneration in vitro and in humans, with promising results. Human umbilical cord mesenchymal stem cells (UC-MSCs) possess a great regenerative and therapeutic potential. Their added benefits comprise ease of collection, endless source of stem cells, less immunorejection, and affordability. Further, their collection does not include the concerns associated with human embryonic stem cells. The purpose of this review is to address the most recent findings about periodontal regenerative mechanisms, different stem cells accessible for periodontal regeneration, and UC-MSCs and their involvement in periodontal regeneration.

Tumour necrosis factor-alpha polymorphism -308 G/a and its protein in subjects with gingivitis

OBJECTIVE

This study examined the association between tumour necrosis factor-alpha (TNF- α) (-308 G/A) polymorphism and gingivitis, and serum and salivary TNF- α levels, in a Mexican population.

MATERIAL AND METHODS

This study enrolled 171 subjects, divided into two groups: healthy subjects and gingivitis patients. TNF- α (-308 G/A) gene polymorphism was analyzed by PCR-RFLP assay. Salivary and serum samples were used to measure cytokine levels through the ELISA technique.

RESULTS

TNF- α (-308 G/A) polymorphism was shown to have a protective effect in carriers of the A/A genotype and allele A. The G/A genotype is associated with an increase in high-density lipoprotein cholesterol (HDL-C) levels in the gingivitis group. Healthy individuals had higher levels of salivary TNF- α and HDL-C, and increased salivary flow. Triglycerides, low-density lipoprotein cholesterol, and very low-density lipoprotein cholesterol levels were increased in the gingivitis group. No statistical differences were found in serum TNF- α levels.

CONCLUSION

Our data demonstrate that the TNF- α -308 A/A genotype exerts a protective effect against gingivitis. Moreover, oral conditions are associated with some biochemical parameters.

Plaque-induced gingivitis: Case definition and diagnostic considerations

OBJECTIVE

Clinical gingival inflammation is a well-defined site-specific condition for which several measurement systems have been proposed and validated, and epidemiological studies consistently indicate its high prevalence globally. However, it is clear that defining and grading a gingival inflammatory condition at a site level (i.e. a "gingivitis site") is completely different from defining and grading a "gingivitis case" (GC) (i.e. a patient affected by gingivitis), and that a "gingivitis site" does not necessarily mean a "GC". The purpose of the present review is to summarize the evidence on clinical, biochemical, microbiologic, genetic markers as well as symptoms associated with plaque-induced gingivitis and to propose a set of criteria to define GC.

IMPORTANCE

A universally accepted case definition for gingivitis would provide the necessary information to enable oral health professionals to assess the effectiveness of their prevention strategies and treatment regimens; help set priorities for therapeutic actions/programs by health care providers; and undertake surveillance.

FINDINGS

Based on available methods to assess gingival inflammation, GC could be simply, objectively and accurately identified and graded using bleeding on probing score (BOP%) CONCLUSIONS: A patient with intact periodontium would be diagnosed as a GC according to a BOP score ≥ 10%, further classified as localized (BOP score ≥ 10% and ≤30%) or generalized (BOP score > 30%). The proposed classification may also apply to patients with a reduced periodontium, where a GC would characterize a patient with attachment loss and BOP score ≥ 10%, but without BOP in any site probing ≥4 mm in depth.

Anti-inflammatory and antioxidative effects of the buds from different species of Populus in human gingival fibroblast cells: Role of bioflavanones

BACKGROUND

Poplar leaf-buds (Populi gemmae) are used traditionally as anti-inflammatory agents to the treatment of skin injuries or cough. They differ in their diverse chemical composition and different types of activities, whose mechanisms are not fully recognized.

PURPOSE

Evaluation and comparison of anti-inflammatory activity of leaf-buds extracts from Populus nigra, P. × berolinensis and P. lasiocarpa and flavanones - pinocembrin and pinostrobin towards human gingival fibroblasts (HGF-1) pro-inflammatory stimulated by silver nanoparticles (AgNPs). Determination of antioxidant activity associated with anti-inflammatory properties by means of bioautographic TLC tests.

METHODS

Phytochemical analysis was performed by TLC and videodensitometry analysis. The extracts were standardized on the pinocembrin and pinostrobin content. Bioautography was performed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and riboflavin-light blue tetrazolium chloride (riboflavin-light-NBT) radicals to assess the extracts and both flavanones radical scavenging properties as well as potential inhibition of xanthine oxidase (XO) activity. The protective effects of poplar buds extract and flavanones - pinocembrin and pinostrobin on HGF-1 line exposured to AgNPs were investigated by analysis of interleukin 6 (IL-6) and interleukin IL-1β (IL-1β) level measured by ELISA kit. The messenger ribonucleic acid (mRNA) of both cytokines was determined by real-time quantitative PCR. The involvement of cyclooxygenase 2 protein (COX-2) was studied using Western blot analysis.

RESULTS

The presence of several flavanones and phenolic acids, which have radical scavenging properties, was revealed in all of the bud poplar extracts analyzed. Treatment with particular flavanones or extracts from buds of P. × berolinensis and P. nigra decreased the IL-6 and IL-1β release in HGF-1 cells and down-regulation of mRNA for both cytokines was observed. The COX-2 protein expression was demonstrated for pinocembrin and P. × berolinensis buds. These effects were not observed for buds from P. lasiocarpa not containing of flavonoids.

CONCLUSION

The potential protective role of pinocembrin and pinostrobin and extracts from buds P. nigra and P. × berolinensis against AgNPs induced inflammation and cytotoxicity in HGF-1 cells is disclosed. In addition, the antioxidant properties of poplar bud extracts have been demonstrated. P. × berolinensis buds showed the highest activity in both the in vitro model and in the bioautographic tests.

Periodontal diseases

Periodontal diseases comprise a wide range of inflammatory conditions that affect the supporting structures of the teeth (the gingiva, bone and periodontal ligament), which could lead to tooth loss and contribute to systemic inflammation. Chronic periodontitis predominantly affects adults, but aggressive periodontitis may occasionally occur in children. Periodontal disease initiation and propagation is through a dysbiosis of the commensal oral microbiota (dental plaque), which then interacts with the immune defences of the host, leading to inflammation and disease. This pathophysiological situation persists through bouts of activity and quiescence, until the affected tooth is extracted or the microbial biofilm is therapeutically removed and the inflammation subsides. The severity of the periodontal disease depends on environmental and host risk factors, both modifiable (for example, smoking) and non-modifiable (for example, genetic susceptibility). Prevention is achieved with daily self-performed oral hygiene and professional removal of the microbial biofilm on a quarterly or bi-annual basis. New treatment modalities that are actively explored include antimicrobial therapy, host modulation therapy, laser therapy and tissue engineering for tissue repair and regeneration.

The use of a disclosing agent during resective periodontal surgery for improved removal of biofilm

A total removal of the bacterial deposits is one of the main challenges of periodontal therapy. A surgical approach is sometimes required in order to allow a correct access to the areas not thoroughly reached during the initial therapy. The present study focuses on the surgical scaling effectiveness in root deposits removal; the potential support of a disclosing agent during this procedure is also evaluated. Forty surgical periodontal patients were randomly divided between surgeries where the operator was informed about a final examination of the residual root deposits and surgeries where the operator was not informed. Straight after scaling procedures a supervisor recorded the O'Leary Plaque Index of the exposed roots by mean of a disclosing agent and the percentage of teeth with residual biofilm. After the stained deposits removal, a second chromatic examination was performed and new data were collected. Mann-Whitney U-test and Wilcoxon test for paired samples were used for comparisons respectively between the two surgery groups and the first and the second chromatic examination; one-sided p-value was set at 0.05. At first examination no significant differences between the two groups were observed regarding Plaque Index (p=0.24) and percentages of teeth with residual biofilm (p=0.07). The 100% removal of roots deposits was never achieved during the study but a significant reduction of 80% of root deposits was observed between first and second examination (p=0.0001). Since root deposits removal during periodontal surgery resulted always suboptimal, the use of a disclosing agent during this procedure could be a useful and practical aid.

Interleukin-1 beta levels in gingival crevicular fluid and serum under naturally occurring and experimentally induced gingivitis

AIMS

To evaluate the interleukin-1 beta (IL-1 beta) levels in gingival crevicular fluid (GCF) and serum in either naturally occurring (N-O) or experimentally induced (E-I) plaque-associated gingivitis.

MATERIAL AND METHODS

Thirty-seven periodontally healthy subjects were evaluated in real life conditions (N-O gingivitis) as well as after 21 days of experimental gingivitis trial (E-I gingivitis). During the experimental gingivitis trial, in one maxillary quadrant (test quadrant), gingival inflammation was induced by oral hygiene abstention, while in the contralateral (control) quadrant, oral hygiene was routinely continued. IL-1 beta concentrations in N-O and E-I gingivitis were investigated for IL-1B(+3954) and IL-1B(-511) gene polymorphisms.

RESULTS

(i) GCF IL-1 beta concentrations in E-I gingivitis were significantly higher compared with N-O gingivitis; (ii) an intra-individual correlation between GCF concentrations of IL-1 beta detected in N-O and E-I gingivitis was observed in control quadrants, but not in test quadrants; (iii) IL-1 beta concentration in GCF was associated with IL-1B(+3954) genotype only at test quadrants; (iv) IL-1 beta was detectable in serum only at low levels in a limited number of subjects, without difference between gingivitis conditions.

CONCLUSIONS

Aspects of the bacterial challenge to the gingival tissues, such as the amount of plaque deposits and plaque accumulation rate, appear to affect the IL-1 beta levels in GCF in subjects with a specific IL-1B genotype.

Gingival transcriptome patterns during induction and resolution of experimental gingivitis in humans

BACKGROUND

To our knowledge, changes in the patterns of whole-transcriptome gene expression that occur during the induction and resolution of experimental gingivitis in humans were not previously explored using bioinformatic tools.

METHODS

Gingival biopsy samples collected from 14 subjects during a 28-day stent-induced experimental gingivitis model, followed by treatment, and resolution at days 28 through 35 were analyzed using gene-expression arrays. Biopsy samples were collected at different sites within each subject at baseline (day 0), at the peak of gingivitis (day 28), and at resolution (day 35) and processed using whole-transcriptome gene-expression arrays. Gene-expression data were analyzed to identify biologic themes and pathways associated with changes in gene-expression profiles that occur during the induction and resolution of experimental gingivitis using bioinformatic tools.

RESULTS

During disease induction and resolution, the dominant expression pathway was the immune response, with 131 immune response genes significantly up- or downregulated during induction, during resolution, or during both at P <0.05. During induction, there was significant transient increase in the expression of inflammatory and oxidative stress mediators, including interleukin (IL)-1 alpha (IL1A), IL-1 beta (IL1B), IL8, RANTES, colony stimulating factor 3 (CSF3), and superoxide dismutase 2 (SOD2), and a decreased expression of IP10, interferon inducible T-cell alpha chemoattractant (ITAC), matrix metalloproteinase 10 (MMP10), and beta 4 defensin (DEFB4). These genes reversed expression patterns upon resolution in parallel with the reversal of gingival inflammation.

CONCLUSIONS

A relatively small subset (11.9%) of the immune response genes analyzed by array was transiently activated in response to biofilm overgrowth, suggesting a degree of specificity in the transcriptome-expression response. The fact that this same subset demonstrates a reversal in expression patterns during clinical resolution implicates these genes as being critical for maintaining tissue homeostasis at the biofilm-gingival interface. In addition to the immune response pathway as the dominant response theme, new candidate genes and pathways were identified as being selectively modulated in experimental gingivitis, including neural processes, epithelial defenses, angiogenesis, and wound healing.

The effect of age on the gingival crevicular fluid composition during experimental gingivitis. A pilot study

Background:

Cytokines have been proposed as potentially useful diagnostic or prognostic markers of periodontal inflammation related alterations during the experimental gingivitis model. The role of ageing in periodontal disease needs further elucidation; therefore investigations of its influence on host response are needed.

Objective:

To study the effect of age on interleukins IL -6, IL-8 and TNF-a levels in gingival crevicular fluid (GCF) and their correlations to clinical parameters during experimental gingivitis.

Materials and Methods: Five young subjects (20-22 years old) and five old subjects (61-65 years old), all periodontal healthy, participated in this clinical trial. A professional plaque control programme was undertaken to establish healthy gingival conditions at baseline. Plaque index (PI), gingival index (GI) were recorded at 60 sites at baseline, after 21 days of no oral hygiene and one week later after professional cleaning and reestablishment of oral hygiene procedures. A total of 180 samples were analyzed with ELISA for levels of IL -6, IL-8 and TNF-a in gingival crevicular fluid. The examination included the mesiobuccal sites of the Ramfjord teeth. Comparisons between and within groups were performed by non-parametric tests (Mann- Withney) and correlations were sought for with Wilcoxon test. Significance was set at p=0.05.

Results:

Results showed significant diferences between the two groups with regard to the plaque and bleeding scores and GCF volume, all of which proved to be more pronounced in old group. With respect to laboratory data, mean cytokine concentrations were in general lower in young group. TNF-a had a steady increase for the adults, which was found to be statistically significant between Days 0 and 21, IL-8 showed a statistically significant decrease at Day 28 in the young group and finally IL-6 showed a fluctuation, which was totally adverse for the two groups at each time point.

Conclusion:

Within the limitations of the present study, age cannot be identified as a factor that strongly affects the cytokine expression and fluctuations even in a well-controlled environment of inflammation, such as experimental gingivitis.

Effect of pretreatment with high-dose ulinastatin in preventing radiation-induced pulmonary injury in rats

In order to develop a better management strategy for radiation-induced pulmonary injury, we compared the protective effect of pretreatment and aftertreatment with different doses of ulinastatin. Two hundred and forty female Sprague-Dawley rats were randomized into five groups. Group R received radiation only, groups P1 and P2 were pretreated with different doses of i.v. ulinastatin for 3 days pre- and 4 days post-irradiation, and groups A1 and A2 were treated for 7 days post-irradiation only. Rats were sacrificed at 2 h, and at 4, 8, 16, and 24 weeks post-irradiation. The expressions of TGF-beta1, TNF-alpha, IL-6, hydroxyproline and laminin were determined. No adverse toxicological effects of ulinastatin pretreatment were observed. Mortality and ratio of fibrotic area was lowest in group P1(5/45; 30.6+/-3.11%, P<0.05 vs. A2). Expressions of TGF-beta1 and IL-6 in group P1 were significantly lowest at 4 weeks (3.01+/-0.35, 549+/-58, 32.3+/-3.27, P<0.01), and expressions of hydroxyproline and laminin were also lowest at 24 weeks (741+/-68 and 82.6+/-6.91, P<0.01) in comparison with other groups. Significant differences were observed in expression of TGF-beta1 and TNF-alpha in lung between group P1 and group A1 at 4 weeks (263+/-11% vs. and 187+/-9%, 189+/-8% vs. 154+/-9%, P<0.01, P<0.05 respectively). Pretreatment with high dose ulinastatin resulted in a milder inflammatory response and suppressed pulmonary fibrosis, which may serve as a favorable management strategy.

The broad effects of the functional IL-10 promoter-592 polymorphism: modulation of IL-10, TIMP-3, and OPG expression and their association with periodontal disease outcome

Periodontal diseases are infectious diseases, in which periodontopathogens trigger chronic inflammatory and immune responses that lead to tissue destruction. It occurs through the generation of metalloproteinases and the activation of bone resorption mechanisms. Anti-inflammatory cytokines such as IL-10 seem to attenuate periodontal tissue destruction through the induction of tissue inhibitors of metalloproteinases (TIMPs) and the inhibitor of osteoclastogenesis osteoprotegerin (OPG). A high individual variation in levels of IL-10 mRNA is verified in periodontitis patients, which is possibly determined by genetic polymorphisms. In this study, the IL-10 promoter -592C/A single nucleotide polymorphism (SNP), which is associated with a decrease in IL-10 production, was analyzed by RFLP in 116 chronic periodontitis (CP) patients and 173 control (C) subjects, and the IL-10, TIMPs, and OPG mRNA expression levels in diseased gingival tissues were determined by real-time-PCR. The IL-10-592 SNP CA (P=0.0012/OR=2.4/CI:1.4-4.1), AA (P=0.0458/OR=2.3/CI:1.1-4.9), and CA+AA (P=0.0006/OR=2.4/CI:1.4-3.4) genotypes and the allele A (P=0.0036/OR=1.7/CI:1.2-2.4) were found to be significantly more prevalent in the CP group when compared with control subjects. Both CA and AA genotypes were associated with lower levels of IL-10, TIMP-3, and OPG mRNA expression in diseased periodontal tissues and were also associated with disease severity as mean pocket depth. Taken together, the results presented here demonstrate that IL10-592 SNP is functional in CP, being associated with lower levels of IL-10 mRNA expression, which is supposed to consequently decrease the expression of the downstream genes TIMP-3 and OPG, and influence periodontal disease outcome.

Association of interleukin-6 (IL-6) haplotypes with plaque-induced gingivitis in children

OBJECTIVES

The proinflammatory cytokine interleukin-6 (IL-6) is a key regulator of the host response to microbial infection and major modulator of extracellular matrix catabolism and bone resorption. The aim of this case-control study was to test differences between children with and without gingivitis in the distribution of IL-6 alleles at positions -174, -572, and -597 and their haplotypes.

MATERIAL AND METHODS

A total of 455 Caucasian children, aged 11 to 13 years, were enrolled in this study. According to gingival bleeding on probing indices, 183 were classified as healthy subjects and 272 as children with plaque-induced gingivitis. DNA for genetic analysis was obtained from buccal epithelial cells and PCR-RFLP methods were used for genotyping three selected IL-6 promoter polymorphisms.

RESULTS

Complex analysis revealed significant differences in haplotype frequencies between patients and healthy subjects (p<0.01). The CGA haplotype was significantly more frequent in children with gingivitis than in healthy subjects (41.5% versus 34.1%). In subanalyses, we found that IL-6 -174C allele was more frequent in patients (44.3%) than in healthy children (36.1%, p=0.016, P(corr)<0.05). Multivariate logistic regression analysis showed that allele C remained a risk factor for gingivitis in children (p=0.03) regardless of plaque or gender. However, the proportions of the IL-6 -597 and -572 genotypes were comparable between the two groups. CONCLUSIONS. Our results indicate that the three promoter polymorphisms in the IL-6 gene act in a cooperative fashion and suggest that IL-6 haplotypes could play a role in the pathogenesis of gingivitis in Caucasian children.