LTFandDEFB1polymorphisms are associated with susceptibility toward chronic periodontitis development

Association of RS1126478 (LTF) with molar-incisor and generalized periodontitis

OBJECTIVES

LTF SNP rs1126478 (T>C) could modulate Lactoferrin function and release and has been associated with periodontal disease in different locations before, but not in America. Thus, this study aimed to assess the association between this SNP and Grade C Periodontitis (Generalized (PerioC-G) and Molar Incisor Pattern (PerioC-MIP)) and seek a relationship between its presence and LTF gingival crevicular fluid (GCF) production.

MATERIAL AND METHODS

Oral cells from 361 Brazilians and 375 North Americans patients (Diseased and Health Controls (PH) from both locations) were collected. DNA was extracted, and a prefabricated probe system determined rs116478 genotyping. Immunoenzymatic analysis detected LTF levels in GCF.

RESULTS

Higher allelic altered-C frequency was associated with PerioC. For PerioC-G, CT and CC genotypes presented a frequency of 44.7% and 34.1%, respectively, while 37.3% and 26.4% were found to PH group (OD=2.1 (p=0.004) for CT and OD=2.3 (p=0.003) for CC). PerioC-G was associated with a lower concentration (742.2±717.9 pg/ml) of LTF than PerioC-MIP (5851±5859.2 pg/ml), p<0.0001. Multiple logistic regression showed that CC genotype impacted LTF levels by acting as a predictor (β =2.457, p=0.02, OD=1.17) despite the site or diagnosis.

CONCLUSION

There is an association of rs1126478 with Grade C periodontitis, mainly the PerioC-G. Lower LTF levels in GCF might be associated with the generalized disease pattern.

CLINICAL RELEVANCE

This study assessed and compared the genetic background in two distinct locations, paving the way for new studies regarding personalized risk and treatment for different ethnicities. As this SNP is in a region related to the antimicrobial function of LTF, it could impact PerioC-MIP and PerioC-G response against periodontopathogens. This discovery opens the way for in vitro studies analyzing the functionality of this SNP, and, in the future, it can be used to treat PerioC, individualizing the phenotypes.

The DEFB1 gene rs11362 A/G genetic variant is associated with risk of developing CAD: a case-control study

BACKGROUND

In the present study, we evaluated whether DEFB1 gene polymorphisms are associated with the presence of coronary artery disease (CAD).

METHODS

Two rs11362 A/G, and rs1800972 C/G gene polymorphisms of DEFB1 gene were genotyped by 5'exonuclease TaqMan assays in 219 patients with CAD and 522 control individuals.

RESULTS

The distribution of rs1800972 C/G polymorphisms was similar in patients with CAD and healthy controls. Nonetheless, under the co-dominant, dominant, recessive, and additive models, the AA genotype of the rs11362 A/G polymorphism was associated with the risk of developing CAD (OR = 1.89 pCCo-Dom = 0.041, OR = 1.46, pCDom = 0.034, OR = 1.69, pCRes = 0.039, and OR = 1.37, pCAdd = 0.012, respectively). In addition, the linkage disequilibrium showed that the 'AG' haplotype was associated with an increased risk of developing CAD (OR = 1.23, p = 0.042). According, with the Genotype-Tissue Expression (GTEx) consortium data, the rs11362 AA genotype is associated with a low mRNA expression of the β-defensin-1 in tissues, such as artery aorta, artery coronary, heart left ventricle, and heart atrial appendage (p < 0.001).

CONCLUSION

This study demonstrates that rs11362 A/G polymorphism of the DEFB1 gene is involved in the risk of developing CAD, and with a low RNA expression of the β-defensin-1 in heart tissue.

Human β-defensins and their synthetic analogs: Natural defenders and prospective new drugs of oral health

As a family of cationic host defense peptides, human β-defensins (HBDs) are ubiquitous in the oral cavity and are mainly synthesized primarily by epithelial cells, serving as the primary barrier and aiming to prevent microbial invasion, inflammation, and disease while maintaining physiological homeostasis. In recent decades, there has been great interest in their biological functions, structure-activity relationships, mechanisms of action, and therapeutic potential in oral diseases. Meanwhile, researchers are dedicated to improving the properties of HBDs for clinical application. In this review, we first describe the classification, structural characteristics, functions, and mechanisms of HBDs. Next, we cover the role of HBDs and their synthetic analogs in oral diseases, including dental caries and pulp infections, periodontitis, peri-implantitis, fungal/viral infections and oral mucosal diseases, and oral squamous cell carcinoma. Finally, we discuss the limitations and challenges of clinical translation of HBDs and their synthetic analogs, including, but not limited to, stability, bioavailability, antimicrobial activity, resistance, and toxicity. Above all, this review summarizes the biological functions, mechanisms of action, and therapeutic potential of both natural HBDs and their synthetic analogs in oral diseases, as well as the challenges associated with clinical translation, thus providing substantial insights into the laboratory development and clinical application of HBDs in oral diseases.

The Impact of IL1B rs1143634 and DEFB1 rs11362 Variants on Periodontitis Risk in Phenylketonuria and Type 1 Diabetes Mellitus Patients in a Latvian Population

OBJECTIVES

Periodontitis is a multifactorial disease that affects approximately 11% of the global population. The objective of this study was to examine whether, among individuals with phenylketonuria and type 1 diabetes mellitus, those with the IL1B rs1143634 and/or DEFB1 rs11362 genetic variants exhibit a higher periodontitis risk compared to healthy controls.

MATERIALS AND METHODS

In all, 43 phenylketonuria patients (aged 12-53), 28 type 1 diabetes mellitus patients (aged 11-40), and 63 healthy controls (aged 12-53) were included. The evaluation of periodontitis risk was conducted using the Silness-Löe plaque index, the Greene-Vermillion index, and an assessment for the necessity of calculus removal. Genetic variants rs1143634 and rs11362 were genotyped from salivary samples using restriction length polymorphism analysis.

RESULTS

The DEFB1 rs11362 variant was associated with higher Silness-Löe and Greene-Vermillion index scores in phenylketonuria patients (p = 0.011 and p = 0.043, respectively). The IL1B rs1143634 variant was associated with lower calculus removal necessity in type 1 diabetes mellitus patients (p = 0.030). Clinical examination showed the worst oral hygiene index scores for PKU patients. PKU patients also reported the least consistent tooth brushing and flossing habits.

CONCLUSIONS

Genetic associations between DEFB1 rs11362 and IL1B rs1143634 variants and oral hygiene indices were observed in the PKU and T1DM groups, suggesting that genetic factors may contribute to periodontal health differences in these populations. Further research with a larger sample size is needed to confirm these findings and develop targeted oral health interventions.

The Genetic Aspects of Periodontitis Pathogenesis and the Regenerative Properties of Stem Cells

Periodontitis (PD) is a prevalent and chronic inflammatory disease with a complex pathogenesis, and it is associated with the presence of specific pathogens, such as Porphyromonas gingivalis. Dysbiosis and dysregulated immune responses ultimately lead to chronic inflammation as well as tooth and alveolar bone loss. Multiple studies have demonstrated that genetic polymorphisms may increase the susceptibility to PD. Furthermore, gene expression is modulated by various epigenetic mechanisms, such as DNA methylation, histone modifications, or the activity of non-coding RNA. These processes can also be induced by PD-associated pathogens. In this review, we try to summarize the genetic processes that are implicated in the pathogenesis of PD. Furthermore, we discuss the use of these mechanisms in diagnosis and therapeutic purposes. Importantly, novel treatment methods that could promote tissue regeneration are greatly needed in PD. In this paper, we also demonstrate current evidence on the potential use of stem cells and extracellular vesicles to stimulate tissue regeneration and suppress inflammation. The understanding of the molecular mechanisms involved in the pathogenesis of PD, as well as the impact of PD-associated bacteria and stem cells in these processes, may enhance future research and ultimately improve long-term treatment outcomes.

Genetic Polymorphism and Gene Expression of β-Defensin-1 in Periodontitis Associated With Type 2 Diabetes Mellitus

Introduction Periodontitis is a multifactorial disease caused by periodontopathic bacteria and influenced by both genetic and environmental factors. Genetic predispositions are found to play a crucial part in the onset and progression of periodontal disease. There is a two-way relationship between diabetes and periodontitis with severe periodontal tissue destruction seen in diabetic patients. Antimicrobial peptide, β-defensin-1 (DEFB1 gene), plays an important role in the innate immune responses and forms the first line of host defense against periodontal pathogens. Single nucleotide polymorphisms (SNPs) in the specific genetic loci of the DEFB1 gene and its expression level could confer a degree of risk or protection from periodontitis associated with diabetes. The present study determined the association between SNPs at the 5' untranslated region (UTR) in the DEFB1 gene and susceptibility to periodontitis associated with type 2 diabetes mellitus (T2DM) and analyzed the effect of 5' UTR polymorphisms on DEFB1 gene expression. Methods SNPs in the 5' UTR of the DEFB1 gene (-20G>A (rs11362), -44C>G (rs1800972), and -52G>A (rs1799946)) were genotyped by polymerase chain reaction (PCR) followed by Sanger sequencing. The study group included periodontitis (n = 40), periodontitis with T2DM (n = 20), and periodontally and systemically healthy as controls (n = 40). DEFB1 gene expression was determined by real-time PCR in the study group comprising periodontitis (n = 20), periodontitis with T2DM (n = 15), and healthy controls (n = 20). The effect of 5' UTR polymorphisms on the expression was analyzed by statistical tools. Results Statistically significant higher prevalence of the variant AA genotype of rs11362 was observed in periodontitis (odds ratio (OR) = 3.64, 95% confidence Interval (CI) = 1.16-11.43, p = 0.04) and periodontitis with T2DM (OR = 5.14, 95% CI = 1.29-20.5, p = 0.03) in comparison with healthy controls. Moreover, there was a significant increase of the variant AA genotype of rs1799946 in periodontitis (OR = 3.88, 95% CI = 1.19-12.68, p = 0.04) compared to healthy controls. DEFB1 gene expression was downregulated in periodontitis and upregulated in periodontitis with T2DM patients when compared to healthy controls but was not statistically significant. No significant association was found for the effect of SNPs of the DEFB1 gene on its expression. Conclusion From the SNP analysis, it can be inferred that the presence of SNPs at the 5' UTR (rs11362 and rs1799946) in the DEFB1 gene may be an important predictive factor for periodontitis.

The Potential Role of Epigenetic Modifications on Different Facets in the Periodontal Pathogenesis

Periodontitis is a chronic inflammatory disease that affects the supporting structures of teeth. In the literature, the association between the pathogenicity of bacteria and environmental factors in this regard have been extensively examined. In the present study, we will shed light on the potential role that epigenetic change can play on different facets of its process, more particularly the modifications concerning the genes involved in inflammation, defense, and immune systems. Since the 1960s, the role of genetic variants in the onset and severity of periodontal disease has been widely demonstrated. These make some people more susceptible to developing it than others. It has been documented that the wide variation in its frequency for various racial and ethnic populations is due primarily to the complex interplay among genetic factors with those affecting the environment and the demography. In molecular biology, epigenetic modifications are defined as any change in the promoter for the CpG islands, in the structure of the histone protein, as well as post-translational regulation by microRNAs (miRNAs), being known to contribute to the alteration in gene expression for complex multifactorial diseases such as periodontitis. The key role of epigenetic modification is to understand the mechanism involved in the gene-environment interaction, and the development of periodontitis is now the subject of more and more studies that attempt to identify which factors are stimulating it, but also affect the reduced response to therapy.

Single Nucleotide Polymorphism and mRNA Expression of LTF in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most prevalent types of cancers worldwide. LTF arrests the G1 to S phase transition of the cell cycle. This study is the first that has aimed to determine the possible association between the LTF polymorphisms (rs2073495, rs1126478, rs34827868, rs1042073, rs4637321, rs2239692 and rs10865941), the mRNA LTF expression, the risk of OSCC and the influence on the TNM staging and histological grading. This study was composed of 176 Polish patients, including 88 subjects diagnosed with OSCC and 88 healthy individuals. QuantStudio Design and Analysis Software v1.5.1 was used for the single nucleotide polymorphism (SNP) analysis and mRNA LTF expression. The G/G genotype of rs2073495 and the G/G genotype of rs4637321 were linked, with an increased risk of OSCC. There were no significant influences between the TNM staging and the histological grading and the LTF genotype. We found no statistically significant dissimilarities in the expression level of LTF genes in the tumour and margin specimens. No association was found between the gene expression levels, the other parameters or LTF polymorphisms in the tumour and margin samples. In conclusion, rs2073495 and rs4637321 polymorphisms may affect the risk of OSCC. These results should be validated on larger and different cohorts to better comprehend the role of the LTF gene in OSCC.

Immunomodulatory and Allergenic Properties of Antimicrobial Peptides

With the growing problem of the emergence of antibiotic-resistant bacteria, the search for alternative ways to combat bacterial infections is extremely urgent. While analyzing the effect of antimicrobial peptides (AMPs) on immunocompetent cells, their effect on all parts of the immune system, and on humoral and cellular immunity, is revealed. AMPs have direct effects on neutrophils, monocytes, dendritic cells, T-lymphocytes, and mast cells, participating in innate immunity. They act on B-lymphocytes indirectly, enhancing the induction of antigen-specific immunity, which ultimately leads to the activation of adaptive immunity. The adjuvant activity of AMPs in relation to bacterial and viral antigens was the reason for their inclusion in vaccines and made it possible to formulate the concept of a “defensin vaccine” as an innovative basis for constructing vaccines. The immunomodulatory function of AMPs involves their influence on cells in the nearest microenvironment, recruitment and activation of other cells, supporting the response to pathogenic microorganisms and completing the inflammatory process, thus exhibiting a systemic effect. For the successful use of AMPs in medical practice, it is necessary to study their immunomodulatory activity in detail, taking into account their pleiotropy. The degree of maturity of the immune system and microenvironment can contribute to the prevention of complications and increase the effectiveness of therapy, since AMPs can suppress inflammation in some circumstances, but aggravate the response and damage of organism in others. It should also be taken into account that the real functions of one or another AMP depend on the types of total regulatory effects on the target cell, and not only on properties of an individual peptide. A wide spectrum of biological activity, including direct effects on pathogens, inactivation of bacterial toxins and influence on immunocompetent cells, has attracted the attention of researchers, however, the cytostatic activity of AMPs against normal cells, as well as their allergenic properties and low stability to host proteases, are serious limitations for the medical use of AMPs. In this connection, the tasks of searching for compounds that selectively affect the target and development of an appropriate method of application become critically important. The scope of this review is to summarize the current concepts and newest advances in research of the immunomodulatory activity of natural and synthetic AMPs, and to examine the prospects and limitations of their medical use.

Human beta-defensin-1 rs2738047 polymorphism is associated with shisha smoking risk among Saudi population

Human β-defensin (HBD), a member of the antimicrobial peptides, is essential for respiratory epithelial cells' microbial defense, and is affected by cigarette smoking (CS). Its expression is upregulated by stimulation from microbes or inflammation. Genetic polymorphisms in the HBD-1 gene have been implicated in the development of various smoking-related diseases, including chronic obstructive pulmonary disease and asthma. Thus, we sought to analyze possible associations between HBD-1 single-nucleotide polymorphism (SNP) in HBD-1 gene and CS in ethnic Saudi Arabian subjects. Variants rs1047031 (C/T), rs1799946 (C/T), rs2738047 (C/T), and rs11362 (C/T) were investigated by genotyping 575 blood specimens from males and females, smokers/non-smokers: 288/287. The CT and CT+TT genotypes of rs1799946 presented an ~5-fold increased correlation with CS among the female smokers, compared with the female controls (OR = 5.473, P = 0.02003; and OR = 5.211, P = 0.02028, respectively), an observation similar to rs11362 SNP in female smokers, but with protective effects in TT genotype, compared with the CC reference allele (OR = 0.143, P = 0.04368). In shisha smokers, the heterozygous CT and the CT/TT genotype of rs2738047 polymorphism showed the same results with ~3-fold increased correlation with CS (OR = 2.788; P = 0.03448), compared with the cigarette smokers category. No significant association was shown in genotypic distributions and allelic frequencies of rs1047031. Further investigations, including large study samples, are required to investigate the effects of shisha on human beta-defensin expression and protein levels.

Comprehensive Analysis of Risk Factors for Periodontitis Focusing on the Saliva Microbiome and Polymorphism

Few studies have exhaustively assessed relationships among polymorphisms, the microbiome, and periodontitis. The objective of the present study was to assess associations simultaneously among polymorphisms, the microbiome, and periodontitis. We used propensity score matching with a 1:1 ratio to select subjects, and then 22 individuals (mean age ± standard deviation, 60.7 ± 9.9 years) were analyzed. After saliva collection, V3-4 regions of the 16S rRNA gene were sequenced to investigate microbiome composition, alpha diversity (Shannon index, Simpson index, Chao1, and abundance-based coverage estimator) and beta diversity using principal coordinate analysis (PCoA) based on weighted and unweighted UniFrac distances. A total of 51 single-nucleotide polymorphisms (SNPs) related to periodontitis were identified. The frequencies of SNPs were collected from Genome-Wide Association Study data. The PCoA of unweighted UniFrac distance showed a significant difference between periodontitis and control groups (p < 0.05). There were no significant differences in alpha diversity and PCoA of weighted UniFrac distance (p > 0.05). Two families (Lactobacillaceae and Desulfobulbaceae) and one species (Porphyromonas gingivalis) were observed only in the periodontitis group. No SNPs showed significant expression. These results suggest that periodontitis was related to the presence of P. gingivalis and the families Lactobacillaceae and Desulfobulbaceae but not SNPs.

Beta-defensin 1 gene polymorphisms in the pathologies of the oral cavity-Data from meta-analysis: Association only with rs1047031 not with rs1800972, rs1799946, and rs11362

OBJECTIVES

The purpose of this meta-analysis was to reveal a potential association of the four functional polymorphisms in human Beta-defensin 1 (DEFB1) gene: rs1047031(c*5G > A) at 3'UTR and rs11362 (-20 G > A), rs1800972(-44 C > G), and rs1799946 (-52 G > A) at 5'UTR with the risk of common oral cavity pathologies that included periodontitis, caries, lichen planus, and recurrent aphthous stomatitis.

METHODS

The relevant studies were obtained by the two researchers from PubMed, Scopus, and Web of Science up to April 29, 2020. The manual search of the reference lists was also performed. Studies on DEFB1 gene polymorphisms and oral cavity disorders, using the case-control genetic association analysis approach, and published as full texts in English were included. To assess the association strength, odds ratios (ORs) with their 95% confidence intervals (CIs) were extracted.

RESULTS

Thirteen publications met the inclusion criteria and were incorporated in this meta-analysis. Statistically significant values of the association tests were found only for the rs1047031 polymorphism. Allele distribution in the rs1047031 polymorphism was significantly associated with susceptibility to oral cavity pathologies (adjusted P value = 0.003). The rare variant allele carriers had a significantly higher risk for oral disasters under recessive (CC vs CT + TT), and CC vs CT models. No significant correlations between rs11362, rs1800972, and rs1799946 and the risk of oral pathologies were revealed.

CONCLUSIONS

Significant association between rs1047031 polymorphism and risk of oral pathologies has been found, and therefore, we suggest to include this polymorphism in future research concerning the genetic background of the oral cavity diseases.

Periodontal health and disease: The contribution of genetics

Periodontitis is an infectious, inflammatory disease that is associated with a complex interplay between specific bacteria, host response, and environmental factors. Because of its high degree of familial aggregation, specifically for the more aggressive forms of the disease, genetics factors have been implicated in disease pathogenesis for several decades. This review provides an overview of what we currently know regarding the genetic and epigenetic contributions to periodontal disease and discusses future opportunities in the field.

Association between genetic polymorphisms in the promoter region of the defensin beta 1 gene and persistent apical periodontitis

AIM

To evaluate the association between the promoter region of defensin beta 1 (DEFB1) genetic polymorphisms and persistent apical periodontitis (PAP) in Brazilian patients.

METHODOLOGY

Seventy-three patients with post-treatment PAP (PAP group) and 89 patients with root filled teeth with healed and healthy periradicular tissues (healed group) were included (all teeth had apical periodontitis lesions at the beginning of the treatment). Patients who had undergone at least 1 year of follow-up after root canal treatment were recalled, and their genomic DNA was extracted from saliva. Two single nucleotide polymorphisms (SNPs) in DEFB1 at the g. -52G>A (rs1799946) and g. -20G>A (rs11362) positions were analysed using real-time polymerase chain reaction. The chi-squared test was performed, and the odds ratios were calculated using Epi Info 3.5.2. Logistic regression analysis in the codominant model, using the time of follow-up as a variable, was used to evaluate the SNP-SNP interaction. All tests were performed with an established alpha of 0.05 (P = 0.05).

RESULTS

For the rs11362 polymorphism in the codominant and recessive models, patients who carried two copies of the T allele had a significantly lower risk of developing PAP (P = 0.040 and P = 0.031, respectively). For the rs1799946 polymorphism in DEFB1 in the codominant and recessive models, carrying one copy of the T allele significantly increased the risk of developing PAP (P = 0.007 and P = 0.031, respectively). In the logistic regression, both polymorphisms were associated with PAP as well as the SNP-SNP interaction (P < 0.0001).

CONCLUSIONS

Polymorphisms in DEFB1 genes were associated with the development of post-treatment persistent apical periodontitis.

Association Between LTF Polymorphism and Risk of HIV-1 Transmission Among Zambian Seropositive Mothers

BACKGROUND

Lactoferrin is a member of the innate immune system acting in the first line of defence against pathogens, and it is known for its antibacterial, antifungal and antiviral activity, including HIV-1. Two polymorphisms, T29A and R47K, in the exon 1 region of the LTF gene (encoding for the lactoferrin protein) were previously described as able to influence the lactoferrin antimicrobial function.

OBJECTIVES

LTF T29A and R47K genetic variants were analysed in a Zambian population to unravel if these polymorphisms could play a role in HIV-1 mother-to-child HIV-1 transmission.

METHODS

LTF T29A and R47K polymorphisms were genotyped, using allelic specific fluorescent probes and real time PCR, in a population comprising 101 HIV-1 positive mothers and 333 children born to seropositive mothers.

RESULTS

Maternal LTF T29A A/A and A/G genotypes were found to be associated with decreased risk of HIV-1 MTCT, being more frequent among non-transmitter mothers respect to transmitter mothers.

CONCLUSION

Our data suggested that maternal LTF genetic background contributes to the susceptibility to HIV-1 transmission from mother to new-borns.

DEFB1 rs11362 Polymorphism and Risk of Chronic Periodontitis: A Meta-Analysis of Unadjusted and Adjusted Data

Objective: Chronic periodontitis (CP) is a growing problem that affects the worldwide population, having significant impacts on people's daily lives and economic development. Genetics is an important component in the determination of individual susceptibility to periodontal diseases. Numerous studies have been performed to investigate the association between beta defensin 1 (DEFB1) rs11362 polymorphism and risk of CP, but the results are still inconclusive. Therefore, we conducted this meta-analysis to ascertain whether this variation in DEFB1 is associated with CP susceptibility.

Methods: The relevant studies were searched in PubMed and Chinese National Knowledge Infrastructure (CNKI) databases up to January 9, 2018. Two independent authors selected citations and extracted the data from eligible studies. Odds ratios (ORs) with their 95% confidence intervals (95% CIs) were used to assess the strength of the association.

Results: Seven case-control studies were included in this meta-analysis. Based on unadjusted data, there was no obvious association between DEFB1 rs11362 polymorphism and CP risk in all genetic models (A vs. G: OR = 0.86, 95%CI = 0.61–1.20; AA vs. GG: OR = 0.83, 95% CI = 00.50–1.39; AG vs. GG: OR = 1.01, 95%CI = 0.73–1.39; AG+AA vs. GG: OR = 0.91, 95% CI = 00.74–1.11; and AA vs. AG+GG: OR = 0.83, 95% CI = 00.57–1.21); the results of adjusted data also showed no significant relationship. Subgroup analyses based on ethnicity, participants' smoking status, HWE in controls and severity of CP all revealed similar results to that of the overall analysis. Sensitivity analysis indicated the results were robust and no evidence of publication bias was found.

Conclusions: Our meta-analysis suggests that DEFB1 rs11362 polymorphism may not have an important effect on the risk of CP. Further large-scale and well-designed studies are necessary to validate our conclusion in the future.

Association of LTA gene haploblock with periodontal disease in Italian adults

BACKGROUND

Periodontitis is a common oral disease caused by host inflammatory response towards bacteria biofilm. The chronic activation of immune response leads to destruction of teeth supporting tissue, bone loss and tooth detachment. Different factors could be involved in the development and severity of the disease; among them the host genetic background should be considered.

OBJECTIVES

In our study, we analysed haploblocks in a genomic region within major histocompatibility complex (MHC) locus aimed at disclosing a possible correlation with the risk of periodontal disease in 602 adult subjects from North-East Italy.

RESULTS

The CTTAC haploblock (formed by LTA-rs2857709, LTA-rs2844484, LTA- rs2229094, LTA-rs2229092 and LTA-rs1041981 polymorphisms) correlated with protection towards periodontitis condition, after regression analysis including age and smoking status as covariates (P-value = 0.015).

CONCLUSION

Our results suggest that a haplotype within LTA gene (encoding for lymphotoxin alpha) is involved in the susceptibility towards chronic periodontitis.

Lack of association between LTF gene polymorphisms and different caries status in primary dentition

OBJECTIVE

Dental caries is related to cariogenic bacteria, salivary components, oral hygiene and host susceptibility. Lactoferrin is an important antimicrobial glycoprotein in saliva; however, the role of the LTF gene in caries susceptibility is unclear. We investigated the association between LTF polymorphisms and the severity of caries.

DESIGN

Our study included 910 healthy paediatric subjects (aged 24-48 months) categorised into three groups: 403 with no caries or white-spot lesions; 230 with moderate caries (8 ≤ dmft ≤ 12); and 277 with severe caries (13 ≤ dmft ≤ 20). Information regarding the subjects' oral habits was gathered using questionnaires. The LTF rs1126477 and rs1126478 polymorphism alleles were genotyped by Sanger sequencing.

RESULTS

The three groups showed no significant differences in LTF polymorphisms alleles, genotypes or haplotypes distribution. Multifactor dimensionality reduction analysis showed that the interactions between breastfeeding for a duration >24 months, night feeding >24 months and high frequency of sweet food intake increased the risk of caries (p = 0.0014); however, we detected no interaction effect between the LTF polymorphisms and oral habits on caries susceptibility.

CONCLUSIONS

The LTF rs1126477 and rs1126478 polymorphisms showed no association with the different levels of caries risk in our Chinese paediatric cohort.

Spontaneous preterm birth: advances toward the discovery of genetic predisposition

Evidence from family and twin-based studies provide strong support for a significant contribution of maternal and fetal genetics to the timing of parturition and spontaneous preterm birth. However, there has been only modest success in the discovery of genes predisposing to preterm birth, despite increasing sophistication of genetic and genomic technology. In contrast, DNA variants associated with other traits/diseases have been identified. For example, there is overwhelming evidence that suggests that the nature and intensity of an inflammatory response in adults and children are under genetic control. Because inflammation is often invoked as an etiologic factor in spontaneous preterm birth, the question of whether spontaneous preterm birth has a genetic predisposition in the case of pathologic inflammation has been of long-standing interest to investigators. Here, we review various genetic approaches used for the discovery of preterm birth genetic variants in the context of inflammation-associated spontaneous preterm birth. Candidate gene studies have sought genetic variants that regulate inflammation in the mother and fetus; however, the promising findings have often not been replicated. Genome-wide association studies, an approach to the identification of chromosomal loci responsible for complex traits, have also not yielded compelling evidence for DNA variants predisposing to preterm birth. A recent genome-wide association study that included a large number of White women (>40,000) revealed that maternal loci contribute to preterm birth. Although none of these loci harbored genes directly related to innate immunity, the results were replicated. Another approach to identify DNA variants predisposing to preterm birth is whole exome sequencing, which examines the DNA sequence of protein-coding regions of the genome. A recent whole exome sequencing study identified rare mutations in genes encoding for proteins involved in the negative regulation (dampening) of the innate immune response (eg, CARD6, CARD8, NLRP10, NLRP12, NOD2, TLR10) and antimicrobial peptide/proteins (eg, DEFB1, MBL2). These findings support the concept that preterm labor, at least in part, has an inflammatory etiology, which can be induced by pathogens (ie, intraamniotic infection) or "danger signals" (alarmins) released during cellular stress or necrosis (ie, sterile intraamniotic inflammation). These findings support the notion that preterm birth has a polygenic basis that involves rare mutations or damaging variants in multiple genes involved in innate immunity and host defense mechanisms against microbes and their noxious products. An overlap among the whole exome sequencing-identified genes and other inflammatory conditions associated with preterm birth, such as periodontal disease and inflammatory bowel disease, was observed, which suggests a shared genetic substrate for these conditions. We propose that whole exome sequencing, as well as whole genome sequencing, is the most promising approach for the identification of functionally significant genetic variants responsible for spontaneous preterm birth, at least in the context of pathologic inflammation. The identification of genes that contribute to preterm birth by whole exome sequencing, or whole genome sequencing, promises to yield valuable population-specific biomarkers to identify the risk for spontaneous preterm birth and potential strategies to mitigate such a risk.

The antimicrobial peptide, human β-defensin-1, potentiates in vitro osteoclastogenesis via activation of the p44/42 mitogen-activated protein kinases

Previous studies have demonstrated increased expression and raised levels of human β-defensin (hBD)-1 in gingival tissue and crevicular fluid of patients with chronic periodontitis and peri-implantitis, oral bone-resorbing diseases caused by enhanced osteoclastogenesis. Therefore, we aimed to investigate the effect of hBD-1 on osteoclast formation and function and to elucidate the involved signaling pathway in vitro. Human peripheral blood mononuclear cells (PBMCs) were first incubated with various doses of hBD-1 and cell viability was assayed by MTT. PBMCs were treated with macrophage-colony stimulating factor and receptor activator of nuclear factor kappa-B ligand (RANKL) in the presence or absence of non-toxic doses of hBD-1. In vitro osteoclastogenesis was analyzed by tartrate-resistant acid phosphatase (TRAP) staining, osteoclast-specific gene expression, and a resorption pit assay. Involvement of mitogen-activated protein kinases (MAPKs) was studied by immunoblotting and specific MAPK inhibitors. HBD-1 potentiated induction of in vitro osteoclastogenesis by RANKL, as shown by significantly increased number of TRAP-positive multinuclear cells and resorption areas on the dentin slices, and further up-regulated expressions of osteoclast-specific genes compared to those by RANKL treatment (p <0.05). However, hBD-1 treatment without RANKL failed to induce formation of osteoclast-like cells. A significant and further increase in transient phosphorylation of the p44/42 MAPKs was demonstrated by hBD-1 co-treatment (p<0.05), consistent with the inhibitory effect by pretreatment with U0126 or PD98059 on hBD-1-enhanced osteoclastogenesis. Collectively, hBD-1 potentiates the induction of in vitro osteoclastogenesis by RANKL via enhanced phosphorylation of the p44/42 MAPKs.