The 3020insC mutation of the NOD2/CARD15 gene in patients with periodontal disease

Osteocyte RANKL Drives Bone Resorption in Mouse Ligature-Induced Periodontitis

Mouse ligature-induced periodontitis (LIP) has been used to study bone loss in periodontitis. However, the role of osteocytes in LIP remains unclear. Furthermore, there is no consensus on the choice of alveolar bone parameters and time points to evaluate LIP. Here, we investigated the dynamics of changes in osteoclastogenesis and bone volume (BV) loss in LIP over 14 days. Time-course analysis revealed that osteoclast induction peaked on days 3 and 5, followed by the peak of BV loss on day 7. Notably, BV was restored by day 14. The bone formation phase after the bone resorption phase was suggested to be responsible for the recovery of bone loss. Electron microscopy identified bacteria in the osteocyte lacunar space beyond the periodontal ligament (PDL) tissue. We investigated how osteocytes affect bone resorption of LIP and found that mice lacking receptor activator of NF-κB ligand (RANKL), predominantly in osteocytes, protected against bone loss in LIP, whereas recombination activating 1 (RAG1)-deficient mice failed to resist it. These results indicate that T/B cells are dispensable for osteoclast induction in LIP and that RANKL from osteocytes and mature osteoblasts regulates bone resorption by LIP. Remarkably, mice lacking the myeloid differentiation primary response gene 88 (MYD88) did not show protection against LIP-induced bone loss. Instead, osteocytic cells expressed nucleotide-binding oligomerization domain containing 1 (NOD1), and primary osteocytes induced significantly higher Rankl than primary osteoblasts when stimulated with a NOD1 agonist. Taken together, LIP induced both bone resorption and bone formation in a stage-dependent manner, suggesting that the selection of time points is critical for quantifying bone loss in mouse LIP. Pathogenetically, the current study suggests that bacterial activation of osteocytes via NOD1 is involved in the mechanism of osteoclastogenesis in LIP. The NOD1-RANKL axis in osteocytes may be a therapeutic target for bone resorption in periodontitis. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Association between periodontal disease and inflammatory bowel disease: a systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review was to investigate the association between periodontal disease (PD) and inflammatory bowel disease (IBD), and its two major forms Crohn's disease (CD) and ulcerative colitis (UC).

MATERIALS AND METHODS

We searched articles in PubMed/MEDLINE, Web of Science, and LILACS published until March 2020. Observational studies evaluating the coexistence of PD in IBD and reported values of clinical periodontal parameters, or radiographic bone loss; and IBD diagnosis established by clinical, radiological, endoscopic and histological criteria were deemed eligible.

RESULTS

A total of 9 studies were included (33,216 individuals). Only one study reported longitudinal data on IBDs onset in patients with PD. Several case-control studies reported coexistence. Meta-analysis showed that the presence of PD was associated with IBD (2.78 [95%CI 1.36-5.69]). PD was strongly associated both with CD (3.41 [95%CI 1.36-8.56]) and UC (3.98 [95%CI 2.02-7.87]).

CONCLUSION

This review presents clear evidence for an association between PD and IBDs. Future studies should avoid non-longitudinal designs and focus on addressing direction. PD screening may be included in the multidisciplinary management of IBD patients. The mere theoretical possibility that PD may predispose to IBDs may be of key significance due to the rising incidence of diseases.

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.

A Gene Module-Based eQTL Analysis Prioritizing Disease Genes and Pathways in Kidney Cancer

Clear cell renal cell carcinoma (ccRCC) is the most common and most aggressive form of renal cell cancer (RCC). The incidence of RCC has increased steadily in recent years. The pathogenesis of renal cell cancer remains poorly understood. Many of the tumor suppressor genes, oncogenes, and dysregulated pathways in ccRCC need to be revealed for improvement of the overall clinical outlook of the disease. Here, we developed a systems biology approach to prioritize the somatic mutated genes that lead to dysregulation of pathways in ccRCC. The method integrated multi-layer information to infer causative mutations and disease genes. First, we identified differential gene modules in ccRCC by coupling transcriptome and protein-protein interactions. Each of these modules consisted of interacting genes that were involved in similar biological processes and their combined expression alterations were significantly associated with disease type. Then, subsequent gene module-based eQTL analysis revealed somatic mutated genes that had driven the expression alterations of differential gene modules. Our study yielded a list of candidate disease genes, including several known ccRCC causative genes such as BAP1 and PBRM1, as well as novel genes such as NOD2, RRM1, CSRNP1, SLC4A2, TTLL1 and CNTN1. The differential gene modules and their driver genes revealed by our study provided a new perspective for understanding the molecular mechanisms underlying the disease. Moreover, we validated the results in independent ccRCC patient datasets. Our study provided a new method for prioritizing disease genes and pathways.

Association of NOD2 Mutations with Aggressive Periodontitis

Aggressive periodontitis (AgP) is characterized by rapid alveolar bone destruction and tooth loss early in life, and its etiology remains unclear. To explore the genetic risk factors of AgP, we performed genome-wide single-nucleotide polymorphism genotyping for identity-by-descent mapping and identified 32 distinct candidate loci, followed by whole exome sequencing with 2 pedigrees of AgP consisting of 3 cases and 1 control in 1 family and 2 sibling cases in the other. After variant filtering procedures and validation by targeted Sanger sequencing, we identified 2 missense mutations at 16q12 in NOD2 (p.Ala110Thr and p.Arg311Trp), which encodes nucleotide-binding oligomerization domain protein 2. We further examined 94 genetically unrelated AgP patients by targeted sequencing of NOD2 and found that 2 patients among them also carried the p.Arg311Trp variant. Furthermore, we found 3 additional missense mutations in this gene (p.His370Tyr, p.Arg459Cys, and p.Ala868Thr). These mutations either had not been previously observed or are extremely rare (frequency <0.001) in Asian populations. NOD2 plays a crucial role in innate immunity as an intracellular receptor initiating nuclear factor κB-dependent and mitogen-activated protein kinase-dependent gene transcription. These results demonstrated NOD2 as a novel gene involved in AgP.

Review article: non-malignant oral manifestations in inflammatory bowel diseases

BACKGROUND

Patients with inflammatory bowel diseases (IBD) may present with lesions in their oral cavity. Lesions may be associated with the disease itself representing an extraintestinal manifestation, with nutritional deficiencies or with complications from therapy.

AIM

To review and describe the spectrum of oral nonmalignant manifestations in patients with inflammatory bowel diseases [ulcerative colitis (UC), Crohn's disease (CD)] and to critically review all relevant data.

METHODS

A literature search using the terms and variants of all nonmalignant oral manifestations of inflammatory bowel diseases (UC, CD) was performed in November 2014 within Pubmed, Embase and Scopus and restricted to human studies.

RESULTS

Oral lesions in IBD can be divided into three categories: (i) lesions highly specific for IBD, (ii) lesions highly suspicious of IBD and (iii) nonspecific lesions. Oral lesions are more common in CD compared to UC, and more prevalent in children. In adult CD patients, the prevalence rate of oral lesions is higher in CD patients with proximal gastrointestinal tract and/or perianal involvement, and estimated to range between 20% and 50%. Oral lesions can also occur in UC, with aphthous ulcers being the most frequent type. Oral manifestations in paediatric UC may be present in up to one-third of patients and are usually nonspecific.

CONCLUSIONS

Oral manifestations in IBD can be a diagnostic challenge. Treatment generally involves managing the underlying intestinal disease. In cases presenting with local disabling symptoms and impaired quality of life, local and systemic medical therapy must be considered and/or oral surgery may be required.

Effect of gene polymorphisms on periodontal diseases

Periodontal diseases are inflammatory diseases of supporting structures of the tooth. It results in the destruction of the supporting structures and most of the destructive processes involved are host derived. The processes leading to destruction and regeneration of the destroyed tissues are of great interest to both researchers and clinicians. The selective susceptibility of subjects for periodontitis has remained an enigma and wide varieties of risk factors have been implicated for the manifestation and progression of periodontitis. Genetic factors have been a new addition to the list of risk factors for periodontal diseases. With the availability of human genome sequence and the knowledge of the complement of the genes, it should be possible to identify the metabolic pathways involved in periodontal destruction and regeneration. Most forms of periodontitis represent a life-long account of interactions between the genome, behaviour, and environment. The current practical utility of genetic knowledge in periodontitis is limited. The information contained within the human genome can potentially lead to a better understanding of the control mechanisms modulating the production of inflammatory mediators as well as provides potential therapeutic targets for periodontal disease. Allelic variants at multiple gene loci probably influence periodontitis susceptibility.

Clinical periodontal and microbiologic parameters in patients with Crohn's disease with consideration of the CARD15 genotype

BACKGROUND

Crohn's disease (CD) was reported to have oral manifestations. However, data on periodontal parameters and oral microbiology in CD are rare. Recent studies showed associations of variants in the caspase recruitment domain (CARD)15 gene with CD that are involved in the immune response toward bacterial products. Our aim is to investigate the periodontal status and prevalence of periodontal pathogens in patients with CD under consideration of the CARD15 polymorphism.

METHODS

Oral soft tissue alterations and periodontal parameters of 147 patients with CD were assessed. Subgingival plaque samples were analyzed for the periodontal pathogens Aggregatibacter actinomycetemcomitans (Aa; previously Actinobacillus actinomycetemcomitans), Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf; previously T. forsythensis), Prevotella intermedia (Pi), and Campylobacter rectus (Cr ) using dot-blot hybridization. CARD15 genotyping was performed with the a polymerase chain reaction (PCR) based assay.

RESULTS

A total of 36.7% of patients had oral manifestations predominated by gingival swellings (27.2%) and hyperplastic lesions of the buccal mucosa (20.4%). The mean probing depth and mean clinical attachment level were 3.6 and 3.8 mm, respectively. A total of 57.8% of the patients had a Community Periodontal Index of Treatment Needs (CPITN) score 3, and 31.3% of had a CPITN score 4. The prevalence of Aa, Pg, Pi, Tf, and Cr was 76.9%, 62.6%, 79.6%, 64.6%, and 94.6%, respectively. Pi was significantly less frequent in carriers of CARD15 mutations compared to the wild type (69.7% versus 87.7%; P = 0.008). All other pathogens and clinical periodontal parameters did not differ significantly as to the CARD15 polymorphism.

CONCLUSIONS

Our findings suggest that patients with CD have an increased prevalence and moderate severity of periodontitis. The colonization of periodontal pathogens, in particular Cr, might be of particular value for the periodontal manifestation of CD. Although a modulating impact on periodontal microbiota can be supposed, our data do not support the role of CARD15 in oral symptoms and periodontal lesions in patients with CD.

Gene polymorphisms in chronic periodontitis

We aimed to conduct a review of the literature for gene polymorphisms associated with chronic periodontitis (CP) susceptibility. A comprehensive search of the literature in English was performed using the keywords: periodontitis, periodontal disease, combined with the words genes, mutation, or polymorphism. Candidate gene polymorphism studies with a case-control design and reported genotype frequencies in CP patients were searched and reviewed. There is growing evidence that polymorphisms in the IL1, IL6, IL10, vitamin D receptor, and CD14 genes may be associated with CP in certain populations. However, carriage rates of the rare (R)-allele of any polymorphism varied considerably among studies and most of the studies appeared under-powered and did not correct for other risk factors. Larger cohorts, well-defined phenotypes, control for other risk factors, and analysis of multiple genes and polymorphisms within the same pathway are needed to get a more comprehensive insight into the contribution of gene polymorphisms in CP.

NOD2/CARD15 disease associations other than Crohn's disease

At this moment, few confirmed associations between NOD2 mutations and diseases other than Crohn's disease (CD) and Blau syndrome (BS) have been reported, but research is ongoing in several fields where a genetic susceptibility factor and/or a role for the innate immune system is suspected. Whether the Crohn's-associated CARD15 mutations lead to a loss or gain of function of the NOD2 receptor is subject to controversy, and by which mechanisms this change in function might increase the susceptibility to CD is still under investigation. The possible involvement of NOD2/CARD15 in the pathogenesis of certain diseases with already (partially) unraveled pathophysiologic mechanisms might contribute to our further understanding of NOD2/CARD15 and its function in CD. We review studies on the association of CARD15 variants with diseases other than CD. The association of NOD2/CARD15 mutations with CD and BS, and possibly also early onset sarcoidosis, suggests a role for the gene in the development of granulomata and granulomatous diseases, possibly by inappropriate activation of the immune system. The data from the oncology field suggest that this inappropriate activation might even lead to uncontrolled proliferation of certain cell types. The studies in allergic diseases and atopy are the largest so far, and the association of NOD2/CARDI5 mutations with atopic phenotypes might be an indication that CARD15 also plays a role in the Th2 pathway. Finally, transplantation studies indicate that the genetic background of a patient should be taken into account when considering hematopoietic stem cell transplantation, given the increased risk of mortality and graft versus host disease observed. Whether NOD2 variants are also associated with an increased risk for infections and sepsis in patients receiving immunosuppressive therapies is unclear.

CARD15 gene variants in aggressive periodontitis

OBJECTIVE

The CARD15 gene encodes a protein that acts as an intracellular receptor of bacterial products, thus playing an important role in the innate immune response. Recently, CARD15 gene variants have been identified as a cause of increased susceptibility to Crohn's disease. The present study aimed to examine a potential association of CARD15 gene variants with aggressive periodontitis susceptibility.

MATERIAL AND METHODS

The three main known CARD15 gene variants (p.R702W, p.G908R, and p.L1007fsX1008) were analysed by direct sequencing of exon 4, 8, and 11 of the gene in a total of 86 generalized aggressive periodontitis patients in comparison with 67 healthy controls.

RESULTS

The mutant allele frequencies of the CARD15 variants were low in the generalized aggressive periodontitis group as well as in the control group and not significantly different (R702W: 3.5% versus 5.2%; G908R: 1.7% versus 1.5%; L1007fsX1008: 5.2% versus 4.5%). Two rare variants (A755V and R791Q), previously described only in patients with other inflammatory diseases, were observed in three patients having aggressive periodontitis but not in controls.

CONCLUSIONS

Unlike in Crohn's disease, our results did not show an association between the three main CARD15 mutations and aggressive periodontitis. The role of rare variants remains unclear.

A645G (Lys216Glu) polymorphism of the bactericidal/permeability-increasing protein gene in periodontal disease

Bactericidal/permeability-increasing protein (BPI) is a member of the pattern recognition receptors of the innate immune system and recognizes lipopolysaccharides (LPS), a bacterial component belonging to the pathogen-associated molecular patterns (PAMPs). BPI mediates the neutralization of LPS and increases the phagocytosis and cytotoxicity against bacteria. Recently, the functionally effective polymorphism A645G resulting in the amino acid alteration Lys216Glu has been described. The aim of the study was to investigate the association of the A645G polymorphism with chronic periodontal disease. The study population comprised 123 patients with periodontal disease (36 with mild, 52 with moderate and 35 with severe periodontitis) and 122 healthy, unrelated control individuals. Genotyping of the BPI gene polymorphism A645G (Lys216Glu) was performed by polymerase chain reaction and restriction fragment length polymorphism analysis. Statistical analysis was carried out employing the chi(2) test with Yates correction. Genotype and allele frequencies of the polymorphism tested herein showed no significant differences between periodontal disease as compared to the control group. The frequencies of the G allele were 52.4% in patients with periodontal disease and 49.2% in the control individuals (P = 0.528). Moreover, no significant associations could be detected after stratification for disease severity and according to gender. The present study does not give evidence for the contribution of the BPI gene to the genetic background of chronic periodontal disease.

Role of the NFKB1 -94ins/delATTG promoter polymorphism in IBD and potential interactions with polymorphisms in the CARD15/NOD2, IKBL, and IL-1RN genes

BACKGROUND

Recently, an association of the NFKB1 polymorphism -94ins/delATTG with ulcerative colitis (UC) has been reported. This 4-bp insertion/deletion polymorphism is localized in the promoter region of the NFKB1 gene and appears to be functionally relevant. The aim of the present study was to confirm the association of the -94ins/delATTG (W/D) NFKB1 promoter polymorphism with UC in a population of German origin and to test for a potential association with Crohn's disease (CD). Furthermore, potential interactions of the -94ins/delATTG polymorphism with the IKBL and the IL-1RN genes should be determined.

MATERIALS AND METHODS

The study population comprised 630 patients with CD, 365 patients with UC, and 974 healthy controls. Genotyping was performed using polymerase chain reaction and restriction fragment length polymorphism analysis. For statistical evaluation, the chi-square test and the Fisher exact test were used.

RESULTS

No significant association of the W/D NFKB1 polymorphism with CD or UC was detected. In addition, no significant interactions between the -94ins/delATTG NFKB1 polymorphism and polymorphisms within the IKBL and the IL-1RN genes, respectively, were found in CD or UC. Also, no significant interactions of the NFKB1 polymorphism with mutations of the CARD15/NOD2 gene and with clinical phenotypes were detected in CD. Moreover, no associations of the NFKB1 polymorphism were found in UC depending on disease localization.

CONCLUSIONS

The present study could not confirm the reported association of the -94ins/delATTG NFKB1 polymorphism with UC and also found no evidence for a role of this polymorphism in CD. The results do not give evidence for a role of this NFKB1 polymorphism in the pathogenesis of UC and CD.

Association of polymorphisms in the interleukin-18 gene in patients with Crohn's disease depending on the CARD15/NOD2 genotype

An increased expression of interleukin-18 (IL-18), a proinflammatory cytokine inducing interferon-gamma, has been found in Crohn's disease (CD). In the IL-18 gene, several partly functional relevant polymorphisms are known. This study sought to investigate associations of IL-18 polymorphisms in inflammatory bowel disease and CD according to CARD15/NOD2 mutation status and clinical phenotypes.

METHODS

The IL-18 polymorphisms -607, -137, and the third position of codon 35 (c35/3) were genotyped in 210 patients with CD, 140 patients with ulcerative colitis, and 265 healthy controls using polymerase chain reaction and restriction fragment length polymorphism analysis.

RESULTS

Frequencies of alleles and genotypes of the 3 polymorphisms and of the respective haplotypes and diplotypes displayed no significant differences between the whole groups of patients with CD and ulcerative colitis, respectively, compared with the controls. After stratification of patients with CD for CARD15/NOD2 status, significant associations of genotypes -137 CC (P = 0.018) and c35/3 CC (P = 0.010) and of the diplotype 2-2 (P = 0.018) were found in cases carrying CARD15/NOD2 mutations. Associations of genotypes -137 GG (P = 0.015) and c35/3 AA (P = 0.030) with colonic disease only in cases positive for CARD15/NOD2 mutations and of the genotype -607 AA (P = 0.007) with fistulas in cases negative for CARD15/NOD2 mutations were observed.

CONCLUSIONS

In this study, significant differences of several genotypes and diplotypes within the IL-18 gene in CD depending on CARD15/NOD2 status have been found. In context with an increased expression of IL-18 in CD, it remains to be shown whether the expression of IL-18 is influenced by CARD15/NOD2 mutation status.

Identification of genetic risk factors for periodontitis and possible mechanisms of action

AIM

To review the literature for genetic risk factors associated with periodontitis.

METHODS

Computerized search of the literature in English using key words: Periodontitis; Genes; Mutation; Polymorphism; Risk.

RESULTS AND CONCLUSIONS

Mutations in the cathepsin C gene (CTSC) have been identified as causal for the Papillon-Lefèvre syndrome (PLS), which includes prepubertal periodontitis (PP). Some CTSC mutations are causal for PP without PLS. No relationship has been demonstrated between CTSC mutations and other forms of periodontitis. Genetic polymorphisms in a candidate gene approach have been explored as risk factors for periodontitis. There is limited evidence that some polymorphisms in the genes encoding interleukins (IL)-1, Fc gamma receptors (Fc gammaR), IL-10 and the vitamin D receptor, may be associated with periodontitis in certain ethnic groups. However relatively large variations in carriage rates of the Rare (R)-alleles among studies on any polymorphism were observed. The available studies appear under-powered and do not adequately take into account other pertinent risk factors for periodontitis. Future studies should include larger cohorts, should clearly define phenotypes and should adequately control for other risk factors. In addition to the candidate gene approach, alternative strategies need to be considered to elucidate the gene variations, which confer risk for periodontitis.