Causal association between periodontitis and risk of rheumatoid arthritis and systemic lupus erythematosus: a Mendelian randomization

Immune-mediated inflammatory diseases and periodontal disease: a bidirectional two-sample mendelian randomization study

BACKGROUND

Previous observational studies have shown a bidirectional association between immune-mediated inflammatory disorders (IMID) and periodontal disease. However, evidence regarding the causal role of IMID and periodontal disease is still lacking. Therefore, we conducted a bidirectional two-sample Mendelian randomization (MR) study to uncover the potential genetic causal effects between IMID and periodontal disease.

METHODS

Bidirectional two-sample MR analysis was employed. Data for ten IMIDs were sourced from genome-wide association studies (GWAS) conducted by the FinnGen Consortium (range from 1023 to 36321 cases) and UK Biobank (UKB) (range from 150 to 17574 cases). Furthermore, GWAS data for periodontal disease were obtained from the FinnGen Consortium (87497 cases), UKB (458 cases), and Gene Lifestyle Interactions in Dental Endpoints (GLIDE) consortium (17,353 periodontitis cases). Subsequently, the causal relationships were analyzed by random effects inverse variance weighting, weighted median, and MR-Egger. Sensitivity analyses were performed using the Cochrane Q test, funnel plot, and Mr-Egger intercept test to ensure robustness. Eventually, replication analysis and meta-analysis across different databases were carried out.

RESULTS

Systemic lupus erythematosus (SLE) [IVW: OR = 1.079 (95% CI: 1.032-1.128) and P < 0.001], Sjogren syndrome [IVW: OR = 1.082 (95% CI: 1.012-1.157) and P = 0.022] and hypothyroidism [IVW: OR = 1.52 (95% CI: 1.13-2.04) and P = 0.005] may increase the risk of periodontal disease. In addition, periodontal disease may reduce the risk of SLE [IVW: OR = 0.8079 (95% CI: 0.6764-0.9650) and P = 0.019] and hyperthyroidism [IVW: OR = 5.59*10-9 (95% CI: 1.43*10-15-2.18*10-2) and P = 0.014]. Meta-analysis indicated a causal correlation between SLE and an increased risk of periodontal disease: [OR = 1.08 (95% CI: 1.03-1.13), P = 0.0009]. No significant evidence suggests bilateral causal relationships between other IMIDs and periodontal disease. No significant estimation of heterogeneity or pleiotropy is detected.

CONCLUSIONS

Our study has confirmed a genetic causal relationship between IMIDs and periodontal disease, thereby unveiling novel potential mechanisms underlying IMIDs and periodontal disease. This discovery is promising in fostering interdisciplinary collaboration between clinicians and stomatologists to facilitate appropriate and precise screening, prevention, and early treatment of IMIDs and periodontal disease.

Periodontal disease increases the severity of chronic obstructive pulmonary disease: a Mendelian randomization study

BACKGROUND

Recent research suggests that periodontitis can increase the risk of chronic obstructive pulmonary disease (COPD). In this study, we performed two-sample Mendelian randomization (MR) and investigated the causal effect of periodontitis (PD) on the genetic prediction of COPD. The study aimed to estimate how exposures affected outcomes.

METHODS

Published data from the Gene-Lifestyle Interaction in the Dental Endpoints (GLIDE) Consortium's genome-wide association studies (GWAS) for periodontitis (17,353 cases and 28,210 controls) and COPD (16,488 cases and 169,688 controls) from European ancestry were utilized. This study employed a two-sample MR analysis approach and applied several complementary methods, including weighted median, inverse variance weighted (IVW), and MR-Egger regression. Multivariable Mendelian randomization (MVMR) analysis was further conducted to mitigate the influence of smoking on COPD.

RESULTS

We chose five single-nucleotide polymorphisms (SNPs) as instrumental variables for periodontitis. A strong genetically predicted causal link between periodontitis and COPD, that is, periodontitis as an independent risk factor for COPD was detected. PD (OR = 1.102951, 95% CI: 1.005-1.211, p = 0.039) MR-Egger regression and weighted median analysis results were coincident with those of the IVW method. According to the sensitivity analysis, horizontal pleiotropy's effect on causal estimations seemed unlikely. However, reverse MR analysis revealed no significant genetic causal association between COPD and periodontitis. IVW (OR = 1.048 > 1, 95%CI: 0.973-1.128, p = 0.2082) MR Egger (OR = 0.826, 95%CI:0.658-1.037, p = 0.1104) and weighted median (OR = 1.043, 95%CI: 0.941-1.156, p = 0.4239). The results of multivariable Mendelian randomization (MVMR) analysis, after adjusting for the confounding effect of smoking, suggest a potential causal relationship between periodontitis and COPD (P = 0.035).

CONCLUSION

In this study, periodontitis was found to be independent of COPD and a significant risk factor, providing new insights into periodontitis-mediated mechanisms underlying COPD development.

The Association of Chronic Periodontitis as a Potential Risk Factor with Rheumatoid Arthritis: A Nested Case-Control Study Using a Korean National Health Screening Cohort

Growing research has proposed that rheumatoid arthritis (RA) and chronic periodontitis (CP) share similar pathophysiological mechanisms involving inflammation and tissue destruction. However, the potential correlation of CP as a contributing factor for the occurrence of RA warrants validation in the Korean population, where both diseases are prevalent, especially considering the increasingly aging demographic in Korea. This study examined 5139 RA cases and 509,727 matched controls from a Korean national cohort dataset (2002-2019) by carefully employing propensity score matching to ensure comparability between groups. Baseline characteristics were compared using standardized differences, and logistic regression was employed to estimate the impact of CP history on RA likelihood while controlling for covariates. We fully examined medical records documenting CP occurrences within the two-year period leading up to the index date, conducting comprehensive subgroup analyses. While a 1-year history of CP did not show a significant association with likelihood of RA, a 2-year history of CP increased RA likelihood by 12%, particularly among older adults, females, rural residents, and those with certain comorbidities such as hypercholesterolemia. Interestingly, this association persisted even among individuals with non-smoking habits, normal weight, and infrequent alcohol consumption. These findings suggest that chronic CP exposure for at least 2 years may independently elevate RA risk in Korean adults. The association in certain subgroups appears to suggest a predisposition toward genetic susceptibilities over lifestyle and environmental factors. Predicting RA in CP patients may be challenging, emphasizing the importance of regular RA screening, especially in high-risk subgroups.

Higher odds of periodontitis in systemic lupus erythematosus compared to controls and rheumatoid arthritis: a systematic review, meta-analysis and network meta-analysis

Introduction

Periodontitis as a comorbidity in systemic lupus erythematosus (SLE) is still not well recognized in the dental and rheumatology communities. A meta-analysis and network meta-analysis were thus performed to compare the (i) prevalence of periodontitis in SLE patients compared to those with rheumatoid arthritis (RA) and (ii) odds of developing periodontitis in controls, RA, and SLE.

Methods

Pooled prevalence of and odds ratio (OR) for periodontitis were compared using meta-analysis and network meta-analysis (NMA).

Results

Forty-three observational studies involving 7,800 SLE patients, 49,388 RA patients, and 766,323 controls were included in this meta-analysis. The pooled prevalence of periodontitis in SLE patients (67.0%, 95% confidence interval [CI] 57.0-77.0%) was comparable to that of RA (65%, 95% CI 55.0-75.0%) (p>0.05). Compared to controls, patients with SLE (OR=2.64, 95% CI 1.24-5.62, p<0.01) and RA (OR=1.81, 95% CI 1.25-2.64, p<0.01) were more likely to have periodontitis. Indirect comparisons through the NMA demonstrated that the odds of having periodontitis in SLE was 1.49 times higher compared to RA (OR=1.49, 95% CI 1.09-2.05, p<0.05).

Discussion

Given that RA is the autoimmune disease classically associated with periodontal disease, the higher odds of having periodontitis in SLE are striking. These results highlight the importance of addressing the dental health needs of patients with SLE.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/ identifier CRD42021272876.

The influence and therapeutic effect of microbiota in systemic lupus erythematosus

Systemic erythematosus lupus (SLE) is an autoimmune disease involving multiple organs that poses a serious risk to the health and life of patients. A growing number of studies have shown that commensals from different parts of the body and exogenous pathogens are involved in SLE progression, causing barrier disruption and immune dysregulation through multiple mechanisms. However, they sometimes alleviate the symptoms of SLE. Many factors, such as genetic susceptibility, metabolism, impaired barriers, food, and sex hormones, are involved in SLE, and the microbiota drives the development of SLE either by depending on or interacting with these factors. Among these, the crosstalk between genetic susceptibility, metabolism, and microbiota is a hot topic of research and is expected to lay the groundwork for the amelioration of the mechanism, diagnosis, and treatment of SLE. Furthermore, the microbiota has great potential for the treatment of SLE. Ideally, personalised therapeutic approaches should be developed in combination with more specific diagnostic methods. Herein, we provide a comprehensive overview of the role and mechanism of microbiota in lupus of the intestine, oral cavity, skin, and kidney, as well as the therapeutic potential of the microbiota.

Genetic causal association between rheumatoid arthritis and periodontitis: a bidirectional two-sample Mendelian randomization analysis

BACKGROUND

A link between rheumatoid arthritis (RA) and periodontitis (PD) has been established. However, their causal relationship remains unclear and the effect of different serotypes of RA on the PD development has not been investigated. This study aims to elucidate the causal association between PD and different serotypes of RA using Mendelian randomization (MR).

METHODS

A bidirectional two-sample MR analysis was performed using available large-scale genome-wide association studies statistics. The inverse-variance weighted (IVW) or multiplicative random-effects IVW was used to determine causality, depending on the heterogeneity of instrumental variables. Additional sensitivity analyses were also performed.

RESULTS

The forward MR analysis identified that seropositive RA (odds ratio (OR), 1.26; 95% confidence interval (CI), 1.07-1.44; p = 0.0018), but not seronegative RA (OR, 1.01; 95% CI, 0.95-1.06; p = 0.9098), was associated with an increased risk of PD. The reverse MR analysis did not show any significant causal effect of PD on RA, independent of the serotypes. The sensitivity tests (p > 0.05) confirmed the robustness and accuracy of these findings.

CONCLUSION

This study revealed that there was a genetic causal effect of seropositive RA on PD, suggesting that this subtype of RA patients may require specific clinical attention to prevent the development of PD.

Appraising causal risk and protective factors for rheumatoid arthritis

Aims

Mendelian randomization (MR) is considered to overcome the bias of observational studies, but there is no current meta-analysis of MR studies on rheumatoid arthritis (RA). The purpose of this study was to summarize the relationship between potential pathogenic factors and RA risk based on existing MR studies.

Methods

PubMed, Web of Science, and Embase were searched for MR studies on influencing factors in relation to RA up to October 2022. Meta-analyses of MR studies assessing correlations between various potential pathogenic factors and RA were conducted. Random-effect and fixed-effect models were used to synthesize the odds ratios of various pathogenic factors and RA. The quality of the study was assessed using the Strengthening the Reporting of Observational Studies in Epidemiology using Mendelian Randomization (STROBE-MR) guidelines.

Results

A total of 517 potentially relevant articles were screened, 35 studies were included in the systematic review, and 19 studies were eligible to be included in the meta-analysis. Pooled estimates of 19 included studies (causality between 15 different risk factors and RA) revealed that obesity, smoking, coffee intake, lower education attainment, and Graves' disease (GD) were related to the increased risk of RA. In contrast, the causality contribution from serum mineral levels (calcium, iron, copper, zinc, magnesium, selenium), alcohol intake, and chronic periodontitis to RA is not significant.

Conclusion

Obesity, smoking, education attainment, and GD have real causal effects on the occurrence and development of RA. These results may provide insights into the genetic susceptibility and potential biological pathways of RA.

Risk factors of systemic lupus erythematosus: an overview of systematic reviews and Mendelian randomization studies

BACKGROUND

The etiology of systemic lupus erythematosus is complex and incurable. A large number of systematic reviews have studied the risk factors of it. Mendelian randomization is an analytical method that uses genetic data as tool variables to evaluate the causal relationship between exposure and outcome.

OBJECTIVE

To review the systematic reviews and Mendelian randomization studies that focused on the risk factors of systemic lupus erythematosus and shed light on the development of treatments for its prevention and intervention.

METHODS

From inception to January 2022, we systematically searched MEDLINE (via PubMed) and Embase for related systematic reviews and Mendelian randomization studies. Extract relevant main data for studies that meet inclusion criteria. The quality of systematic reviews was assessed by using Assessment of Multiple Systematic Reviews 2 (AMSTAR-2). Finally, the risk factors are scored comprehensively according to the results' quantity, quality, and consistency.

RESULTS

Our study involved 64 systematic reviews and 12 Mendelian randomization studies. The results of systematic reviews showed that diseases (endometriosis, atopic dermatitis, allergic rhinitis), lifestyle (smoking, drinking, vaccination), and gene polymorphism influenced the incidence of systemic lupus erythematosus. The results of Mendelian randomization studies identified the role of disease (periodontitis, celiac disease), trace elements (selenium, iron), cytokines (growth differentiation factor 15), and gut microbiome in the pathogenesis of systemic lupus erythematosus.

CONCLUSION

We should pay attention to preventing and treating systemic lupus erythematosus in patients with endometriosis, celiac disease, and periodontitis. Take appropriate dietary supplements to increase serum iron and selenium levels to reduce the risk of systemic lupus erythematosus. There should be no excessive intervention in lifestyles such as smoking and drinking.

Mendelian randomization study on the causal effects of systemic lupus erythematosus on major depressive disorder

The vast majority of epidemiological studies suggested a link between systemic lupus erythematosus (SLE) and major depressive disorder (MDD). However, the causality for SLE on the risk of MDD remained unknown due to confounding factors or reverse causality. Herein, we investigated the causality between SLE and MDD in those of European ancestry by a Mendelian randomization (MR) approach. Summary genetic data of cases with SLE/MDD were derived from independent largest public genome-wide association study. Forty-six single nucleotide polymorphisms associated with SLE were used as instrumental variables. The main causal inference was carried out using the MRE-IVW method. Additional, reverse-direction MR and multivariable MR analyses were further performed. Result indicated that SLE was causally associated with a lower risk of MDD (using the MRE-IVW method, odds ratio [OR] = 0.983, 95% confidence interval [CI] = 0.974-0.991, p = 1.18 × 10^-4). Complementary analysis found no heterogeneity or horizontal pleiotropy. Multivariate MR analysis yielded consistent results (OR =  0.981; 95% CI = 0.969-0.993; p = 2.75 × 10^-3). Reverse-direction MR analysis suggested non-causal relationship of MDD on the risk of SLE (using the IVW method, OR = 0.846, 95% CI = 0.345-2.072; p = 0.714). Thus, this is the first study providing evidence of potential causal links between SLE and MDD and further related research is needed.

Could AMPs and B-cells be the missing link in understanding periodontitis?

Periodontal diseases are common inflammatory conditions characterized by bone loss in response to simultaneous bacterial aggression and host defenses. The etiology of such diseases is still not completely understood, however. It has been shown that specific pathogens involved in the build-up of dysbiotic biofilms participate actively in the establishment of periodontitis. This multifactorial pathology also depends on environmental factors and host characteristics, especially defenses. The immune response to the pathogens seems to be critical in preventing the disease from starting but also contributes to tissue damage. It is known that small molecules known as antimicrobial peptides (AMPs) are key actors in the innate immune response. They not only target microbes, but also act as immuno-modulators. They can help to recruit or activate cells such as neutrophils, monocytes, dendritic cells, or lymphocytes. AMPs have already been described in the periodontium, and their expression seems to be connected to disease activity. Alpha and beta defensins and LL37 are the AMPs most frequently linked to periodontitis. Additionally, leukocyte infiltrates, especially B-cells, have also been linked to the severity of periodontitis. Indeed, the particular subpopulations of B-cells in these infiltrates have been linked to inflammation and bone resorption. A link between B-cells and AMP could be relevant to understanding B-cells' action. Some AMP receptors, such as chemokines receptors, toll-like receptors, or purinergic receptors, have been shown to be expressed by B-cells. Consequently, the action of AMPs on B-cell subpopulations could participate to B-cell recruitment, their differentiation, and their implication in both periodontal defense and destruction.

DNMT3B (rs2424913) polymorphism is associated with systemic lupus erythematosus alone and with co-existing periodontitis in a Brazilian population

The association between Periodontitis and Systemic Lupus Erythematosus (SLE) has been primarily based on their similar pathophysiology and both are associated with genetic polymorphisms.

OBJECTIVES

To investigate an association between the methylation-related gene polymorphisms DNMT3B (rs2424913) and MTHFR (rs1801133) to Systemic Lupus Erythematosus (SLE) and Periodontitis.

METHODOLOGY

In total, 196 individuals of all genders aged 24 to 60 years old were allocated into four groups based on their systemic and periodontal status, namely: Healthy control (n=60), periodontitis (n=51), SLE (n=47), and SLE + periodontitis (n=38). Individuals with SLE were stratified according to disease activity (SLEDAI) in inactive or active. We performed polymorphism analysis using PCR-RFLP with genomic DNA from mouthwash. We analyzed data using Fisher's Exact, Chi-square test, and regression models.

RESULTS

Periodontal status were similar in subjects with periodontitis alone and combined with SLE. SLE patients with periodontitis had a longer SLE diagnosis than SLE only (p=0.001). For DNMT3 B polymorphism, the periodontitis, SLE, and Inactive SLE + periodontitis groups showed a higher frequency of T allele and TT genotypes compared to healthy controls (p<0.05). Regression analyses showed that the TT genotype is a strong risk factor for periodontitis (OR=4.53; CI95%=1.13-18.05) and also for SLE without periodontitis (OR=11.57; CI95%=3.12-42.84) and SLE with periodontitis (OR=5.27; CI95%=1.25-22.11) when compared to control.

CONCLUSION

SLE patients with periodontitis had a longer length of SLE diagnosis. The DNMT3B (rs2424913) polymorphism was associated with periodontitis and SLE alone or combined with periodontitis. Our study contributes to understanding the genetic mechanisms involved in periodontitis and SLE susceptibility.

Systems Biology in Periodontitis

Systems biology is a promising scientific discipline that allows an integrated investigation of host factors, microbial composition, biomarkers, immune response and inflammatory mediators in many conditions such as chronic diseases, cancer, neurological disorders, and periodontitis. This concept utilizes genetic decoding, bioinformatic, flux-balance analysis in a comprehensive approach. The aim of this review is to better understand the current literature on systems biology and identify a clear applicability of it to periodontitis. We will mostly focus on the association between this condition and topics such as genomics, transcriptomics, proteomics, metabolomics, as well as contextualize delivery systems for periodontitis treatment, biomarker detection in oral fluids and associated systemic conditions.

Periodontitis is associated with higher subclinical atherosclerosis in patients with systemic lupus erythematosus

AIM

To determine periodontitis prevalence in patients with systemic lupus erythematosus (SLE) and to assess whether periodontitis in SLE patients is associated with a greater subclinical atherosclerosis.

METHODS

An observational case-control study was conducted in SLE (cases) and patients without any rheumatic diseases (controls), matched for sex. Sociodemographic and cardiometabolic variables were gathered, and SLE activity was assessed through several indexes. Periodontal examination registered probing pocket depth, clinical attachment level, bleeding on probing, plaque index, and tooth loss. Subclinical atherosclerosis was assessed by measuring the carotid-femoral pulse wave velocity (PWV) by Doppler velocimetry, homocysteine levels, C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR). Bivariate analyses and logistic regression were used to assess the association of any of the studied variables with SLE.

RESULTS

Seventy-one cases and 72 controls were included in the study. Thirty-nine SLE patients (54.9%) were diagnosed with periodontitis, compared with 16 controls (22.2%). High levels of PWV (≥7.7 m/s, 75th percentile) were shown by 44.3% of the cases vs. 22.4% of the controls (p = .011). Among SLE patients, those with periodontitis showed higher PWV values (8.1 ± 1.52 vs. 7.16 ± 1.11 m/s, p = .006) and higher homeostasis model assessment index (indicative of insulin resistance) (1.7 ± 0.73 vs. 2.92 ± 3.05, p = .028) compared to those with periodontal health. Logistic regression showed that waist circumference (OR 1.06, 95% CI 1.01-1.12, p = .015); ESR (OR 1.09, 95% CI 1.03-1.16, p = .003); and bleeding on probing (OR 1.1, 95% CI 1.01-1.19, p = .018) were associated with the risk of SLE.

CONCLUSION

Systemic lupus erythematosus patients showed a higher periodontitis percentage than controls. Higher PWV values were found in SLE patients with periodontitis, indicating a higher prevalence of subclinical atherosclerosis. Patients with higher gingival bleeding showed a higher risk of SLE.

Mendelian Randomization Analysis Suggests No Associations of Herpes Simplex Virus Infections With Multiple Sclerosis

Previous studies have suggested an association between infection with herpes simplex virus (HSV) and liability to multiple sclerosis (MS), but it remains largely unknown whether the effect is causal. We performed a two-sample Mendelian randomization (MR) study to explore the relationship between genetically predicted HSV infection and MS risk. Genetic instrumental variables for diagnosed infections with HSV (p < 5 × 10^–6) were retrieved from the FinnGen study, and single nucleotide polymorphisms associated with circulating immunoglobulin G (IgG) levels of HSV-1 and HSV-2 and corresponding summary-level statistics of MS were obtained from genome-wide association studies of the European-ancestry. Inverse-variance weighted MR was employed as the primary method and multiple sensitivity analyses were performed. Genetically proxied infection with HSV was not associated with the risk of MS (odds ratio [OR], 0.96; 95% confidence interval [CI], 0.90–1.02; p = 0.22) per one-unit increase in log-OR of herpes viral infections. MR results provided no evidence for the relationship between circulating HSV-1 IgG levels and MS risks (OR = 0.91; 95% CI, 0.81–1.03; p = 0.37), and suggested no causal effect of HSV-2 IgG (OR = 1.04; 95% CI, 0.96–1.13; p = 0.32). Additional sensitivity analyses confirmed the robustness of these null findings. The MR study did not support the causal relationship between genetic susceptibly to HSV and MS in the European population. Further studies are still warranted to provide informative knowledge, and triangulating evidence across multiple lines of evidence are necessary to plan interventions for the treatment and prevention of MS.

Association Between a History of Nontyphoidal Salmonella and the Risk of Systemic Lupus Erythematosus: A Population-Based, Case-Control Study

Objective

We investigated the correlation between nontyphoidal Salmonella (NTS) infection and systemic lupus erythematosus (SLE) risk.

Methods

This case-control study comprised 6,517 patients with newly diagnosed SLE between 2006 and 2013. Patients without SLE were randomly selected as the control group and were matched at a case-control ratio of 1:20 by age, sex, and index year. All study individuals were traced from the index date back to their NTS exposure, other relevant covariates, or to the beginning of year 2000. Conditional logistic regression analysis was used to analyze the risk of SLE with adjusted odds ratios (aORs) and 95% confidence intervals (CIs) between the NTS and control groups.

Results

The mean age was 37.8 years in the case and control groups. Females accounted for 85.5%. The aOR of having NTS infection were significantly increased in SLE relative to controls (aOR, 9.20; 95% CI, 4.51-18.78) in 1:20 sex-age matching analysis and (aOR, 7.47; 95% CI=2.08-26.82) in propensity score matching analysis. Subgroup analysis indicated that the SLE risk was high among those who dwelled in rural areas; had rheumatoid arthritis, multiple sclerosis, or Sjogren’s syndrome; and developed intensive and severe NTS infection during admission.

Conclusions

Exposure to NTS infection is associated with the development of subsequent SLE in Taiwanese individuals. Severe NTS infection and other autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, or Sjogren’s syndrome also contributed to the risk of developing SLE.

Periodontitis and Systemic Lupus Erythematosus: A systematic review and meta-analysis

This systematic review and meta-analysis evaluated the association between periodontitis (PD) and systemic lupus erythematosus (SLE). A systematic search was conducted through the following electronic databases: Cochrane Library, MEDLINE, EMBASE, Scopus, LILACS, CINAHL and SIGLE (System for Information on Grey Literature in Europe) for relevant publications up to September 2020 with no language restriction. The association between PD and SLE was assessed by the prevalence of PD in SLE patients (both sex and females only) as the primary outcome. Secondary outcomes included differences in common gingival parameters including probing pocket depth (PPD), clinical attachment level (CAL), disease activity index (SLEDAI) scores of SLE patients with or without PD. A total of 1183 citations and 22 full text articles were screened. Eighteen articles were included in the qualitative synthesis, and 13 in the quantitative analysis. SLE diagnosis was associated with greater odds of PD (OR = 1.33, 95% Confidence Interval [CI]: 1.20-1.48), but these were non-significant when examined in females (OR = 3.20, 95%CI: 0.85-12.02). Patients with SLE exhibited no differences in PPD (SMD: -0.09 mm, 95%CI: -0.45-0.27) and CAL (SMD: 0.05 mm, 95%CI: -0.30-0.40) when compared with systemically healthy controls. PD diagnosis was, however, associated with higher SLEDAI scores in patients suffering from SLE (SMD: 0.68, 95% CI: 0.03-1.32). PD and SLE are both inflammatory diseases and their association could be bi-directional. This review suggested that the patients with SLE have greater odds of suffering with PD. Further investigations are required to assess the association between PD and SLE.

Causal risk and protective factors in rheumatoid arthritis: A genetic update

The characterization of risk and protective factors in complex diseases such as rheumatoid arthritis (RA) has evolved from epidemiological studies, which test association, to the use of Mendelian randomization approaches, which test direct relationships. Indeed, direct associations with the mucosal origin of RA are retrieved with periodontal disease (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans predominantly), interstitial lung involvement, tobacco smoking and air pollutants. Next, factors directly associated with an acquired immune response include genetic factors (HLA DRB1, PTPN22), capacity to produce anti-modified protein antibodies (AMPA), and relatives with a history of autoimmune diseases. Finally, factors can be also classified according to their direct capacity to interfere with the IL-6/CRP/sIL-IL6R proinflammatory pathway as risk factor (body fat, cardiometabolic factors, type 2 diabetes, depressive syndrome) or either as protective factors by controlling of sIL-6R levels (higher education level, and intelligence). Although some co-founders have been characterized (e.g. vitamin D, physical activity, cancer) the direct association with sex-discrepancy, pregnancy, and infections among other factors remains to be better explored.

Two-Sample Mendelian Randomization Analysis of Associations Between Periodontal Disease and Risk of Cancer

Background

Observational studies indicate that periodontal disease may increase the risk of colorectal, lung, and pancreatic cancers. Using a 2-sample Mendelian randomization (MR) analysis, we assessed whether a genetic predisposition index for periodontal disease was associated with colorectal, lung, or pancreatic cancer risks.

Methods

Our primary instrument included single nucleotide polymorphisms with strong genome-wide association study evidence for associations with chronic, aggressive, and/or severe periodontal disease (rs729876, rs1537415, rs2738058, rs12461706, rs16870060, rs2521634, rs3826782, and rs7762544). We used summary-level genetic data for colorectal cancer (n = 58 131 cases; Genetics and Epidemiology of Colorectal Cancer Consortium, Colon Cancer Family Registry, and Colorectal Transdisciplinary Study), lung cancer (n = 18 082 cases; International Lung Cancer Consortium), and pancreatic cancer (n = 9254 cases; Pancreatic Cancer Consortia). Four MR approaches were employed for this analysis: random-effects inverse-variance weighted (primary analyses), Mendelian Randomization-Pleiotropy RESidual Sum and Outlier, simple median, and weighted median. We conducted secondary analyses to determine if associations varied by cancer subtype (colorectal cancer location, lung cancer histology), sex (colorectal and pancreatic cancers), or smoking history (lung and pancreatic cancer). All statistical tests were 2-sided.

Results

The genetic predisposition index for chronic or aggressive periodontitis was statistically significantly associated with a 3% increased risk of colorectal cancer (per unit increase in genetic index of periodontal disease; P = .03), 3% increased risk of colon cancer (P = .02), 4% increased risk of proximal colon cancer (P = .01), and 3% increased risk of colorectal cancer among females (P = .04); however, it was not statistically significantly associated with the risk of lung cancer or pancreatic cancer, overall or within most subgroups.

Conclusions

Genetic predisposition to periodontitis may be associated with colorectal cancer risk. Further research should determine whether increased periodontitis prevention and increased cancer surveillance of patients with periodontitis is warranted.

Systemic Lupus Erythematosus and Periodontal Disease: A Complex Clinical and Biological Interplay

Reports on the association of periodontal disease (PD) with systemic lupus erythematosus (SLE) have regularly been published. PD is a set of chronic inflammatory conditions linked to a dysbiotic microbial biofilm, which affects the periodontal tissues, resulting eventually in their destruction and contributing to systemic inflammation. SLE is a multi-system chronic inflammatory autoimmune disease that has a wide range of clinical presentations, touching multiple organ systems. Many epidemiological studies have investigated the two-way relationship between PD and SLE, though their results are heterogeneous. SLE and PD are multifactorial conditions and many biological-based hypotheses suggest common physiopathological pathways between the two diseases, including genetics, microbiology, immunity, and environmental common risk factors. By focusing on recent clinical and translational research, this review aimed to discuss and give an overview of the relationship of SLE with PD, as well as looking at the similarities in the immune-pathological aspects and the possible mechanisms connecting the development and progression of both diseases.

Assessment of Bidirectional Relationships Between Polycystic Ovary Syndrome and Periodontitis: Insights From a Mendelian Randomization Analysis

Background

Observational studies have indicated an association between polycystic ovary syndrome (PCOS) and periodontitis, but it is unclear whether the association is cofounded or causal. We conducted a two-sample Mendelian randomization (MR) study to investigate the bidirectional relationship between genetically predicted PCOS and periodontitis.

Methods

From two genome-wide association studies we selected 13 and 7 single nucleotide polymorphisms associated with PCOS and periodontitis, respectively, as instrumental variables. We utilized publicly shared summary-level statistics from European-ancestry cohorts. To explore the causal effect of PCOS on periodontitis, 12,289 cases of periodontitis and 22,326 controls were incorporated, while 4,890 cases of PCOS and 20,405 controls in the reverse MR. Inverse-variance weighted method was employed in the primary MR analysis and multiple sensitivity analyses were implemented.

Results

Genetically determined PCOS was not causally associated with risk of periodontitis (odds ratio 0.97; 95% confidence interval 0.88-1.06; P = 0.50) per one-unit increase in the log-odds ratio of periodontitis. Similarly, no causal effect of periodontitis on PCOS was shown with the odds ratio for PCOS was 1.17 (95% confidence interval 0.91-1.49; P = 0.21) per one-unit increase in the log-odds ratio of periodontitis. Consistent results were yielded via additional MR methods. Sensitivity analyses demonstrated no presence of horizontal pleiotropy or heterogeneity.

Conclusion

The bidirectional MR study couldn't provide convincing evidence for the causal relationship between genetic liability to PCOS and periodontitis in the Europeans. Triangulating evidence across further observational and genetic-epidemiological studies is necessary.