Abstract
Background
Polymorphisms in inflammasome genes can modulate the host immune response and influence individual susceptibility to periodontitis. The present study was designed to investigate the association between polymorphisms in NLRP3, AIM2, and IFI16 genes and periodontitis.
Methods
This case control study was conducted among a total of 240 participants, consisting of 80 periodontally healthy (Group H), 80 with stage III grade B periodontitis (Group PB), and 80 with stage III grade C periodontitis (Group PC). All periodontal clinical parameters and demographic data were recorded. DNA samples were obtained from peripheral blood. The NLRP3 rs4612666, AIM2 rs2793845, and IFI16 rs75985579 polymorphisms were genotyped using allele-specific probes through real-time polymerase chain reaction (RT-PCR) analysis. Chi-square and Fisher’s exact tests (p < 0.05) were used to compare genotype and allele frequencies between the groups. The association between the polymorphisms and advanced attachment loss in different genetic models was evaluated with logistic regression analysis.
Results
The analysis revealed no significant differences in the genotypic and allelic distributions of NLRP3 rs4612666, AIM2 rs2793845, and IFI16 rs75985579 polymorphisms among the groups (p > 0.05). Individuals with advanced attachment loss exhibited higher frequencies of CT and TT genotypes and T allele of the NLRP3 rs4612666 polymorphism (p < 0.05). Also the NLRP3 rs4612666 polymorphism was associated with the advanced attachment loss in recessive and additive models; while TT genotype showed a significant association under the codominant model (p < 0.05).
Conclusions
No association was observed between NLRP3 rs4612666, AIM2 rs2793845, and IFI16 rs75985579 polymorphisms and susceptibility to periodontitis in this population and under this study design. However, the T allele of NLRP3 rs4612666 polymorphism may be associated with an increased risk of advanced attachment loss.
Trial registration
This study was registered on clinicaltrials.gov (Trial registration number: NCT06465095; Protocol ID: 09-2023-1700; Date of registration: 2024-06-18).
Keywords: Inflammasome, Gene, Polymorphism, Periodontitis
Background
Inflammasomes are multiprotein complexes that play an important role in detecting inflammatory signals and triggering the innate immune response. First described by Martinon and colleagues in 2002, inflammasomes assemble in the cytoplasm during infection or cellular stress [1] and typically consist of a sensor pattern-recognition receptor (PRR), an adaptor molecule known as apoptosis-related speck-like protein containing a caspase activation and recruitment domain (ASC), and the effector protease caspase-1. Various types of inflammasomes can assemble, each designated according to the specific PRR that initiates its activation. The sensor components of inflammasomes are derived from several PRR families, including the nucleotide-binding domain leucine-rich repeat-containing receptors (NLRs) and the absent in melanoma 2 (AIM2)-like receptors (ALRs) [2]. Inflammasome activation triggers caspase-1 to process IL-1β and IL-18 into active cytokines and, at the same time, initiates pyroptotic cell death in immune cells. Aberrant inflammasome activity has been linked to various multifactorial diseases, including bacterial, fungal, and viral infections, as well as cancer, autoimmune, cardiovascular, and neurological disorders [3, 4]. The role of inflammasomes in the development of periodontitis was first highlighted in 2009, with the study showing that NLRP3 expression was elevated in gingival tissues of periodontitis patients compared to healthy controls [5]. A significant elevation in salivary NLRP3 and IL-1β levels has been observed in individuals with chronic and aggressive periodontitis [6]. Another research also revealed increased salivary levels of AIM2, IFI16, and IL-18 in affected individuals, which correlated with clinical periodontal parameters [7].
Periodontitis, a chronic multifactorial inflammatory disease, constitutes a significant public health issue due to its high prevalence [8–10]. Bacterial invasion of periodontal tissues triggers activation of the immune response [11] and the persistence of pathogens and impaired immune balance result in progressive destruction of periodontal tissues [12, 13]. The development of periodontal diseases results from a multifactorial interaction among microbial biofilm, environmental factors, and the host response. Genetic factors play a crucial role in determining susceptibility and may influence the onset and progression of periodontal diseases [14]. Genetic polymorphisms can lead to alterations in the encoded protein or its expression levels, potentially influencing both innate and adaptive immune responses and, consequently, the course of a disease. Moreover, certain genetic polymorphisms may have a protective effect against disease development [11].
A single nucleotide polymorphism (SNP) refers to a substitution of a single nucleotide that is found in more than 1% of the population [15]. Recent studies have shown that SNPs in inflammasome genes influence host immune responses, thereby increasing individual susceptibility to periodontitis [16–18]. These genetic variations may alter the expression or activity of inflammasome components, contributing to a heightened inflammatory state in periodontal tissues.
The NLRP3 rs4612666 polymorphism has been reported to be associated with rheumatoid arthritis [19], type 2 diabetes mellitus [20], and periodontitis [16]. In addition, the AIM2 rs2793845 polymorphism has been linked to coronary heart disease and periodontitis [17], while the IFI16 rs75985579 polymorphism has also been associated with periodontitis [18]. However, studies investigating the effects of these polymorphisms on the development of periodontitis are limited, and no research to date has evaluated individuals with Stage III Grade B and C periodontitis.
In the present study, we hypothesized that the NLRP3 rs4612666, AIM2 rs2793845, and IFI16 rs75985579 polymorphisms increase susceptibility to periodontitis. Therefore, the study aimed to investigate the distribution of these polymorphisms and their association with periodontitis in periodontally healthy individuals and in patients with Stage III Grade B and Stage III Grade C periodontitis.
Methods
The present case control study was approved by the Clinical Research Ethics Committee of Faculty of Medicine Marmara University (Protocol no: 09-2023-1700) and registered at clinicaltrials.gov with the number NCT06465095. All clinical procedures were performed according to the Helsinki Declaration of 1975, as revised in 2013 and informed consent was obtained from each attendee prior to study.
Study Population and Sample Size Calculation
An a priori sample size calculation was performed based on the study by de Alencar et al. [16], which investigated the effect of NLRP3 gene polymorphism on periodontitis susceptibility. Using an α value of 0.05 and a statistical power of 80%, the required sample size was determined as 80 individuals per group. A total of 240 participants were recruited from the Department of Periodontology and Oral Diagnostics, Faculty of Dentistry, Marmara University, Istanbul, Türkiye, between July 2024 and January 2025, comprising 80 periodontally healthy controls, 80 patients with Stage III Grade B periodontitis, and 80 patients with Stage III Grade C periodontitis.
A medical and dental history, intraoral photos and panoramic radiographs were taken from all participants. The inclusion criteria for all individuals were: being systemically healthy, between the ages of 18–65, nonsmoker, no pregnancy or lactation, no periodontal treatment in past 6 months, no usage of antibiotics in past 3 months, no usage of any medication including steroids, immunosuppressants, nonsteroidal anti-inflammatory drugs, antiepileptic drugs, calcium channel blockers.
The periodontal status of all participants were determined according to the diagnostic criteria of the Classification of Periodontal and Peri-Implant Diseases and Conditions at the 2017 World Periodontology Workshop and the subjects classified into three groups. Periodontally healthy group included individuals who had: clinical absence of periodontal inflammation and no history of periodontitis, probing depth (PD) ≤ 3 mm and < 10% bleeding on probing (BOP), no evidence of detectable bone and/or attachment loss [21]. Patients with stage III periodontitis had ≥ 20 teeth (excluding third molars), radiographic bone loss extending mid-third of the root or beyond, clinical attachment level (CAL) ≥ 5 mm. The grade of periodontitis was determined with indirect evidence of progression through % of bone loss/age at the most affected tooth in the dentition. When the values of % bone loss/age were between 0.25 and 1.0, the patients were assigned to Grade B, if higher than 1.0, the patients were assigned to Grade C [22]. All patients were additionally assessed based on CAL. Participants were categorized into two groups: those presenting with at least one site exhibiting CAL ≥ 7 mm and those with CAL < 7 mm.
Periodontal Examination
Periodontal examination was performed by a single trained and calibrated examiner (NS) using a periodontal probe (University of North Carolina, PCPUNC15, Hu-Friedy Ins Co, USA). Prior to the study, intra-examiner calibration was performed in ten periodontitis patients who were not included in the study. PD and CAL measurements were recorded twice at a 1-day interval, with reliability coefficients of 0.93 for PD and 0.92 for CAL. PD, CAL, plaque index (PI) [23], gingival index (GI) [24], BOP were measured at six sites per tooth in all teeth except third molars.
Sample Collection, DNA Isolation and Genotyping
Blood samples were collected from antecubital fossa of each participants and stored in sterile ethylene diamine tetra-acetic acid tubes (BD Vacutainer, ABD) until the analysis day. DNA isolation from the collected blood samples was performed using the PureLink (Invitrogen, Van Allen Way Carlsbad, CA, ABD) isolation kit, following the recommended protocol. The Invitrogen Qubit 4 Fluorometer was employed to verify that equal and appropriate amounts of DNA isolated from the blood samples were added to the tubes for real-time polymerase chain reaction (RT-PCR). Genotyping of NLRP3 rs4612666, AIM2 rs2793845, and IFI16 rs75985579 polymorphisms was carried out on the StepOnePlus Real-Time PCR System (Thermo Fisher Scientific, CA, USA) using TaqMan SNP Genotyping Kits in accordance with the manufacturer’s instructions. PCR reactions were performed in a total reaction volume of 10 µL, including 1 µL of genomic DNA, 5 µL of Genotyping Master Mix (Applied Biosystems, Foster City, CA), 0.5 µL of Genotyping Assay (Applied Biosystems), and 3.5 µL of nuclease-free water. RT-PCR cycling parameters comprised enzyme activation at 60 °C, initial denaturation at 95 °C for 10 min, 40 cycles of denaturation at 95 °C for 15 s, and 40 cycles of annealing at 60 °C for 60 s. Duplicate assays were performed for each sample as well as a no template control (NTC).
Statistical analysis
Statistical analyses of the data obtained in the study were performed using the SPSS statistical program (Version 25.0; IBM Corp., Armonk, NY, ABD). The distribution of the data was assessed with the Shapiro–Wilk test. For the comparison of multiple groups with non-normally distributed quantitative variables, the Kruskal–Wallis test was applied, and in cases of significance, pairwise comparisons were conducted using the Bonferroni-corrected Mann–Whitney U test. Chi-square and Fisher’s exact tests were employed to compare sex distribution, as well as genotype and allele frequencies of NLRP3, AIM2, and IFI16 polymorphisms between groups. The conformity of genotype frequencies with Hardy–Weinberg equilibrium was assessed separately for each study group using the Chi-square test by comparing observed and expected genotype frequencies. Logistic regression analysis was used to evaluate the association between polymorphisms and advanced attachment loss in different genetic models: codominant, dominant, recessive, and additive. Unadjusted logistic regression analyses were first conducted. Age and sex were then included as covariates to account for potential confounding effects, and adjusted models were subsequently generated. A p-value of < 0.05 was considered statistically significant.
Results
The study population and clinical parameters
The demographic data and clinical periodontal parameters of the individuals included in the study are presented in Table 1. Significantly lower mean ages (years) were observed in the H group (29.07 ± 4.48) compared with the periodontitis groups, and in the PC group (37.71 ± 7.84) compared with the PB group (44.09 ± 8.20) (p < 0.0001) (Table 1). Gender distributions among groups were similar (p > 0.05) (Table 1).
Table 1.
Demographic and clinical characteristics of the study groups
| Demographic and clinical data | Ha N = 80 |
PBb N = 80 |
PCc N = 80 |
p (a−b−c) | p (a−b) | p (a−c) | p (b−c) |
|---|---|---|---|---|---|---|---|
|
Age (Mean ± SD) |
29.07 ± 4.48 | 44.09 ± 8.20 | 37.71 ± 7.84 | < 0.0001* | < 0.0001** | < 0.0001** | < 0.0001** |
|
Gender N(%) Female Male |
50 (62.50) 30 (37.50) |
52 (65.00) 28 (35.00) |
39 (48.75) 41 (51.25) |
0.080† | |||
|
PI (Mean ± SD) |
0.43 ± 0.26 | 2.13 ± 0.26 | 2.11 ± 0.49 | < 0.0001* | < 0.0001** | < 0.0001** | 0.165** |
|
GI (Mean ± SD) |
0.31 ± 0.24 | 1.95 ± 0.30 | 1.96 ± 0.43 | < 0.0001* | < 0.0001** | < 0.0001** | 0.627** |
|
BOP (%) (Mean ± SD) |
7.21 ± 2.85 | 69.26 ± 13.35 | 71.96 ± 14.82 | < 0.0001* | < 0.0001** | < 0.0001** | 0.125** |
|
PD (mm) (Mean ± SD) |
1.83 ± 0.35 | 3.49 ± 0.49 | 3.67 ± 0.71 | < 0.0001* | < 0.0001** | < 0.0001** | 0.327** |
|
CAL (mm) (Mean ± SD) |
3.75 ± 0.59 | 4.20 ± 1.10 | 0.071¶ |
PI Plaque index, GI Gingival index, BOP Bleeding on probing, PD Probing depth, CAL Clinical attachment level, H Healthy, PB Grade B periodontitis, PC Grade C periodontitis, SD Standart deviation
*Kruskal-Wallis test
**Mann Whitney U test with Bonferroni correction
†Chi-square test
¶Mann Whitney U test
p < 0.05, Statistical differences are marked in bold
Multiple group comparisons demonstrated statistically significant differences in PI, GI, BOP percentage and PD values (p < 0.0001) (Table 1). Pairwise analyses revealed that these periodontal parameters were significantly lower in the H group compared with the periodontitis groups (p < 0.0001). No significant differences were observed between periodontitis groups for all periodontal clinical parameters (p > 0.05) (Table 1).
Genotype and allele distributions
The genotype and allele distributions of NLRP3 rs4612666, AIM2 rs2793845, and IFI16 rs75985579 polymorphisms obtained by RT-PCR in the study groups are presented in Table 2. The expected and observed genotype frequencies of NLRP3 and AIM2 were consistent with Hardy–Weinberg equilibrium in all groups, whereas the IFI16 polymorphism conformed to equilibrium only in the PB group (p > 0.05) (Table 2). Overall, genotype and allele distributions of NLRP3, AIM2, and IFI16 polymorphisms were similar among the groups (p > 0.05) (Table 2).
Table 2.
Genotype and allele distributions of NLRP3, AIM2, and IFI16 polymorphisms in all study groups
| Gene (SNP ID) |
Genotypes and alleles | H N = 80 N (%) |
PB N = 80 N (%) |
PC N = 80 N (%) |
χ2 p value |
Fisher’s exact p value |
|---|---|---|---|---|---|---|
|
NLRP3 (rs4612666) |
CC CT TT |
45 (56.25) 32 (40.00) 3 (3.75) |
36 (45.00) 39 (48.75) 5 (6.25) |
38 (47.50) 33 (41.25) 9 (11.25) |
0.263 | 0.291 |
| HWE | 0.649 | 0.421 | 0.905 | |||
| C | 122 (76.25) | 111 (69.38) | 109 (68.13) | 0.224 | 0.220 | |
| T | 38 (23.75) | 49 (30.62) | 51 (31.87) | |||
|
AIM2 (rs2793845) |
TT GT GG |
61 (76.25) 18 (22.50) 1 (1.25) |
68 (85.00) 11 (13.75) 1 (1.25) |
64 (80.00) 15 (18.75) 1 (1.25) |
0.724 | 0.679 |
| HWE | 1.000 | 0.961 | 1.000 | |||
| T | 140 (87.50) | 147 (91.87) | 143 (89.37) | 0.438 | 0.463 | |
| G | 20 (12.50) | 13 (8.13) | 17 (10.63) | |||
|
IFI16 (rs75985579) |
GG AG AA |
60 (75.00) 20 (25.00) 0 (0) |
63 (78.75) 15 (18.75) 2 (2.50) |
52 (65.00) 28 (35.00) 0 (0) |
0.056 | 0.054 |
| HWE | - | 0.691 | - | |||
| G | 140 (87.50) | 141 (88.12) | 132 (82.50) | 0.282 | 0.302 | |
| A | 20 (12.50) | 19 (11.88) | 28 (17.50) |
HWE Hardy-Weinberg equilibrium, H Healthy, PB Grade B periodontitis, PC Grade C periodontitis
p < 0.05
Considering the presence of sites with CAL ≥ 7 mm, the distributions of inflammasome gene polymorphisms are presented in Table 3. Although no overall group (H, PB and, PC) differences were observed in genotype distributions, the CT and TT genotypes and the T allele frequency of the NLRP3 rs4612666 polymorphism were significantly higher in individuals with at least one site exhibiting CAL ≥ 7 mm (p < 0.05), while no significant associations were detected for AIM2 rs2793845 and IFI16 rs75985579 polymorphisms (p > 0.05) (Table 3).
Table 3.
Genotype and allele distributions according to presence of at least one site exhibiting CAL ≥ 7 mm
| Gene (SNP ID) |
Genotypes and alleles | CAL < 7 mm N = 115 N (%) |
CAL ≥ 7 mm N = 125 N (%) |
χ2 p value |
OR (95% CI) |
Fisher’s exact p value |
|---|---|---|---|---|---|---|
|
NLRP3 (rs4612666) |
CC CT TT |
66 (57.39) 46 (40.00) 3 (2.61) |
53 (42.40) 58 (46.40) 14 (11.20) |
0.009 0.094 0.004 0.038 |
1.57 (0.93–2.67) 5.81 (1.59–21.29) 3.70 (1.00-13.66) |
0.008 0.108 0.004 0.060 |
|
C T |
178 (77.39) 52 (22.61) |
164 (65.60) 86 (34.40) |
0.004 | 1.80 (1.20–2.69) | 0.005 | |
|
AIM2 (rs2793845) |
TT GT GG |
90 (78.26) 24 (20.87) 1 (0.87) |
103 (82.40) 20 (16.00) 2 (1.60) |
0.560 0.343 0.647 0.476 |
0.73 (0.38–1.41) 1.75 (0.16–19.60) 2.40 (0.20-28.45) |
0.552 0.404 1.000 0.593 |
|
T G |
204 (88.70) 26 (11.30) |
226 (90.40) 24 (9.60) |
0.541 | 0.83 (0.46–1.50) | 0.554 | |
|
IFI16 (rs75985579) |
GG AG AA |
88 (76.52) 27 (23.48) 0 |
87 (69.60) 36 (28.80) 2 (1.60) |
0.237 0.312 - - |
1.35 (0.76–2.41) - - |
0.279 0.378 - - |
|
G A |
203 (88.26) 27 (11.74) |
210 (84.00) 40 (16.00) |
0.178 | 1.43 (0.85–2.42) | 0.190 |
CAL Clinical attachment level, OR Odds ratio, CI Confidence interval
p < 0.05, Statistical differences are marked in bold
Association of polymorphisms with advanced attachment loss (presence of at least one site exhibiting CAL ≥ 7 mm) in different genetic models are presented in Table 4. According to the logistic regression analysis, the NLRP3 rs4612666 polymorphism was associated with advanced attachment loss in dominant, recessive and additive models and TT genotype for codominant models (p < 0.05). After adjusting for age and gender, association remained significant in recessive, additive, and codominant models (p < 0.05) (Table 4).
Table 4.
Association of polymorphisms with advanced attachment loss (CAL ≥ 7 mm) in different genetic models
| Gene (SNP ID) |
Model | Genotypes | Adjusted OR (95% CI) |
p |
|---|---|---|---|---|
|
NLRP3 (rs4612666) |
Codominant |
CC vs. CT CC vs. TT |
1.40 (0.76–2.58) 5.30 (1.29–21.72) |
0.275 0.021 |
| Dominant | CC vs. CT + TT | 1.66 (0.92–2.98) | 0.091 | |
| Recessive | CC + CT vs. TT | 4,59 (1.15-18,39) | 0.031 | |
| Overdominant | CC + TT vs. CT | 1.19 (0.66–2.16) | 0.560 | |
| Additive | CC vs. CT vs. TT | 1.75 (1.08–2.84) | 0.024 | |
|
AIM2 (rs2793845) |
Codominant |
TT vs. GT TT vs. GG |
2.58 (0.17–39.94) 0.75 (0.35–1.62) |
0.499 0.470 |
| Dominant | TT vs. GG + GT | 0.81 (0.39–1.71) | 0.586 | |
| Recessive | TT + GT vs. GG | 2.76 (0.18–42.55) | 0.466 | |
| Overdominant | GG + TT vs. GT | 0.74 (0.35–1.59) | 0.438 | |
| Additive | TT vs. GT vs. GG | 0.90 (0.46–1.77) | 0.764 | |
|
IFI16 (rs75985579) |
Codominant |
GG vs. AG GG vs. AA |
1.65 (0.85–3.21) - |
0.142 0.999 |
| Dominant | GG vs. AA + AG | 1.69 (0.87–3.27) | 0.123 | |
| Recessive | GG + AG vs. AA | - | 0.999 | |
| Overdominant | GG + AA vs. AG | 1.69 (0.87–3.28) | 0.123 | |
| Additive | GG vs. AG vs. AA | 1.70 (0.89–3.26) | 0.111 |
CAL Clinical attachment level, OR Odds ratio, CI Confidence interval
p < 0.05, Statistical differences are marked in bold
Discussion
The pathogenesis of periodontitis involves host–pathogen interactions; however, genetic variations substantially affect the host immune response, influencing both susceptibility and disease progression [11]. SNPs in inflammasome-related genes can alter the inflammatory response by affecting gene expression or protein function, ultimately increasing the risk of periodontitis. The aim of this study was to analyze the genotype and allele distributions of NLRP3 rs4612666, AIM2 rs2793845, and IFI16 rs75985579 polymorphisms, explore their association with periodontitis, and compare them with those observed in healthy individuals.
Inflammasomes function as multiprotein complexes that sense inflammatory stimuli and activate innate immune responses. Dysregulated inflammasome activity contributes to the pathogenesis of various disorders, including metabolic, neurodegenerative, and inflammatory diseases [25]. Evidence from clinical studies has shown that inflammasomes play a critical role in the pathogenesis of periodontal diseases, as indicated by their increased expression in the saliva and gingival tissues of individuals with periodontitis [5, 7]. Activation of inflammasomes induces the production of pro-inflammatory cytokines such as IL-1β, which are key mediators of the inflammatory response against disease. However, aberrant inflammasome activation can result in uncontrolled cytokine production, leading to periodontal tissue destruction.
The NLRP3 rs4612666 polymorphism has been implicated in various systemic diseases. The association between the NLRP3 rs4612666 polymorphism and rheumatoid arthritis was evaluated in individuals from Taiwan, and the T allele of this polymorphism was reported to increase susceptibility to rheumatoid arthritis. The study also demonstrated that NLRP3 inflammasome activation leads to cytokine stimulation and plays a crucial role in the pathogenesis and progression of autoimmune diseases [19]. In another study conducted among Chinese individuals, the C allele was shown to significantly increase disease risk. A study from Turkiye explored the relationship between NLRP3 gene variations and type 2 diabetes mellitus. The rs4612666 variant showed significance only in the heterozygous model, suggesting that the CC genotype may be associated with an elevated risk of the disease [20]. A study conducted in a Czech population to investigate the association between inflammasome gene polymorphisms and recurrent aphthous stomatitis demonstrated that carriers of the TT genotype of the NLRP3 rs4612666 variant exhibited an increased risk of developing the disease [26]. In our study, the genotype and allele distributions of the NLRP3 rs4612666 polymorphism were compared between periodontitis patients and healthy controls, revealing no significant differences among groups. However, individuals with advanced attachment loss exhibited significantly higher frequencies of the CT and TT genotypes and the T allele. A previous study carried out in Iraqi Arab individuals aged 30–55 years found no significant association between the NLRP3 rs4612666 variant and periodontitis [27]. Similar findings were reported in a Colombian cohort, where no overall association was observed. Nevertheless, a significant interaction effect was detected between the CT/CC genotypes of the NLRP3 gene and individuals aged over 48 years, as well as between the CC genotype and smoking status [28]. The NLRP3 rs4612666 polymorphism has been investigated in a mixed population living in southern Brazil. The study included 186 individuals over 30 years of age diagnosed with stage II or III, grade B periodontitis, and 208 controls who were either periodontally healthy or had localized gingivitis. The NLRP3 rs4612666 T/C genotype was found to be associated with periodontal disease, independent of smoking status. Furthermore, men carrying this polymorphism were found to have a higher risk of developing periodontal disease compared with women [16]. A study involving 486 Czech individuals assessed the NLRP3 rs4612666 polymorphism in patients with type 2 diabetes mellitus and chronic periodontitis. The TT genotype was associated with a higher risk of chronic periodontitis compared with the CT + CC genotypes, in both systemically healthy individuals and those with type 2 diabetes mellitus [29]. Considering the variability of findings in the literature, further research is warranted to clarify the potential association between the NLRP3 rs4612666 polymorphism and periodontitis.
AIM2 and IFI16 inflammasomes recognize intracellular microbial or endogenous DNA and play essential roles in the innate immune response. They induce the release of pro-inflammatory cytokines, which helps regulate immune activity and has been associated with various inflammatory diseases, including periodontitis. A study evaluating the effect of the AIM2 rs2793845 polymorphism on periodontitis development in healthy individuals and those with coronary heart disease included 120 Iraqi participants aged 35–75 years. The T allele and the GT and TT genotypes were associated with an increased susceptibility to periodontitis, independent of coronary heart disease [17]. Barrientos and Cruz investigated the association of the AIM2 rs76457189 and IFI16 rs75985579 variants with periodontitis in African American individuals. The IFI16 rs75985579 polymorphism was significantly associated with periodontitis, with carriers of at least one A allele exhibiting more than a twofold higher likelihood of developing the disease. The AIM2 rs76457189 polymorphism, however, showed a negative association, indicating a lower risk among individuals carrying the G allele. Gene interaction analysis demonstrated that the two SNPs formed a haplotype, and the co-occurrence of both alleles increased the risk of periodontitis more than fourfold [18]. Previous limited studies have reported an association between the AIM2 rs2793845 and IFI16 rs75985579 variants and periodontitis; however, our study found no significant differences in the genotype or allele distributions of these polymorphisms among the study groups in the present sample. Nevertheless, the absence of an association in this cohort should be interpreted with caution, as it does not exclude a potential role for AIM2 and IFI16 in periodontitis susceptibility in other populations, under different clinical or environmental contexts, or through alternative genetic variants. These variations across studies underscore the need for further comprehensive research to determine the contribution of these polymorphisms to periodontitis susceptibility.
Previous studies evaluating the association of NLRP3 rs4612666, AIM2 rs2793845, and IFI16 rs75985579 polymorphisms with periodontitis have reported varying outcomes. These discrepancies may be attributed to differences in study design, sample size, ethnic background, or population heterogeneity. Although the study included an adequate sample size, it should be acknowledged that the participants were recruited from a single center and represent a single population, which constitutes an inherent methodological limitation and may limit the generalizability of the findings to the overall Turkish population. Additional limitations include the inability to incorporate all stages and grades of periodontitis according to the current disease classification and the analysis being restricted to a single SNP for each of the NLRP3, AIM2, and IFI16 inflammasome genes, potentially excluding other relevant variants.
Conclusion
Considering the limitations of the study, NLRP3 rs4612666, AIM2 2793845, and IFI16 75985579 polymorphisms were analyzed in periodontally healthy individuals and in patients with stage III grade B and grade C periodontitis, and genotype and allele distributions were found to be similar among the groups in the present sample and within the context of this study. However, there may be a relationship between the severity of attachment loss and the T allele of the NLRP3 rs4612666 polymorphism. To validate this finding, further multicenter studies with larger sample sizes and advanced methodologies are warranted. The discovery of genetic markers linked to susceptibility to periodontitis may facilitate the early identification of high-risk individuals and support the development of personalized treatment approaches.
Acknowledgements
The authors express their sincere appreciation to all individuals who generously volunteered to take part in the research protocols of this study.
Abbreviations
- AIM2
Absent in melanoma 2
- ALR
AIM2-like receptors
- ASC
Apoptosis-related speck-like protein containing a caspase activation and recruitment domain
- BOP
Bleeding on probing
- CAL
Clinical attachment level
- GI
Gingival index
- H
Healthy
- NLR
Nucleotide-binding domain leucine-rich repeat-containing receptors
- PB
Periodontitis grade B
- PC
Periodontitis grade C
- PD
Probing depth
- PI
Plaque index
- PRR
Pattern-recognition receptor
- RT-PCR
Real-time polymerase chain reaction
- SNP
Single nucleotide polymorphism
Authors’ contributions
NS: Methodology, Investigation, Data interpretation, Writing manuscript; ÖÖY: Genetic analysis; BTA: Genetic Analysis, Writing manuscript, HÖÖ: Methodology, Investigation, Writing-review & editing, Project administration. All authors approved the final manuscript for publication.
Funding
This study was supported by grants from the Marmara University Scientific Research Projects Coordination Unit with TDH-2024-11209 protocol ID.
Data availability
The data supporting this study are included in the article. Further details can be obtained from the corresponding authors upon reasonable request.
Declarations
Ethical Approval and Consent to Participate
The study was conducted in accordance with the Declaration of Helsinki and approved by Marmara University Faculty of Medicine Clinical Research Ethics Committee (08.12.2023-09.2023.1700). This trial was registered in ClinicalTrials.gov (Registration number: NCT06465095). Informed consent was provided by all participants included in the study.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Nurbanu Saka, Özlem Özge Yılmaz and Beste Tacal Aslan contributed equally to this work.
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Data Availability Statement
The data supporting this study are included in the article. Further details can be obtained from the corresponding authors upon reasonable request.