Genetic links between anti-inflammatory drug targets and oral diseases

Inflammation originates as a fundamental defense mechanism of biological systems, serving as a critical pathophysiological pathway in disease progression (Yi 2019). Numerous oral pathologies present with characteristic inflammatory manifestations within the oral microenvironment (Nguyen et al. 2023). Clinically, untreated gingival inflammation progresses to periodontitis through well-documented pathological mechanisms (Eltay and Dyke 2023), while immune-mediated inflammatory responses drive the pathogenesis of recurrent oral ulcerations (Kurgan and Kantarci 2018). A chronic inflammatory state can foster a tumorigenic microenvironment conducive to neoplastic transformation and metastatic dissemination (Häyrinen-Immonen et al. 1991). Emerging evidence substantiates significant associations between persistent oral inflammation and systemic pathologies including hypertension, diabetes mellitus (Comen et al. 2018), and cardiovascular disorders, which subsequently exert synergistic effects on disease advancement through complex pathobiological interactions (Uyar and Davutoglu 2016; Mutlu and Mirici 2018).

Excessive inflammatory responses have been demonstrated to exacerbate pathological progression, precipitating tissue damage and potential functional impairment. Consequently, anti-inflammatory pharmacological agents constitute a cornerstone of clinical therapeutic approaches (Wang et al. 2023a). The widespread clinical utilization of these therapeutics has prompted extensive investigation into their modulatory effects on oral pathophysiological processes (Yuan et al. 2024; Zhang et al. 2019). In clinical dentistry, these agents are indispensable and are primarily divided into two categories: steroidal anti-inflammatory drugs (SAIDs), such as Dexamethasone and Prednisone, and nonsteroidal anti-inflammatory drugs (NSAIDs), including Aspirin, Ibuprofen, and Paracetamol (Prabhu et al. 2021), their clinical applications are broad; topical glucocorticoids are frequently prescribed for immune-mediated conditions like oral lichen planus, while NSAIDs are a mainstay for managing acute inflammatory pain from pulpitis and for postoperative analgesia. These drugs exert their effects via diverse molecular pathways (Auger et al. 2024).The anti-inflammatory efficacy of GCs involves sophisticated regulation of mitochondrial bioenergetics in macrophages, facilitating sustained production of anti-inflammatory metabolites including itaconate. Mechanistically, glucocorticoid receptors engage with pyruvate dehydrogenase (PDH), enhancing enzymatic activity and accelerating tricarboxylic acid (TCA) cycle flux in macrophages (Auger et al. 2024; Stifel et al. 2022). In contrast, NSAIDs primarily mediate anti-inflammatory effects through competitive inhibition of cyclooxygenase (COX) isoforms (Brown et al. 2001), effectively blocking the enzymatic conversion of arachidonic acid to prostaglandins (Vane 1971; Bindu et al. 2020).

GCs are frequently prescribed for the management of oral mucosal pathologies, whereas NSAIDs constitute a mainstay therapeutic intervention for postoperative analgesia in oral surgical procedures (Bailey et al. 2014; Moore et al. 2018; Shirvani et al. 2017), particularly in the context of carious lesion progression. The inflammatory cascade in dental pulp tissue has been mechanistically linked to COX activity and prostaglandin E2 (PGE2) biosynthesis (Petrini et al. 2012). Notably, empirical evidence demonstrates the efficacy of paracetamol in attenuating postoperative discomfort following endodontic interventions (Machado et al. 2024). Nevertheless, the epidemiological correlation between anti-inflammatory pharmacotherapy and oral disease susceptibility remains controversial. Clinical interpretations are frequently confounded by diagnostic variability, methodological heterogeneity, and residual confounding factors across observational studies. For instance, the chemopreventive potential of NSAIDs in oral squamous cell carcinoma continues to engender scholarly debate (Tsujii and DuBois 1995; Hong et al. 2000; Kelley et al. 1997; Eling et al. 1990), with longitudinal cohort analyses failing to substantiate protective associations (Friis et al. 2006). To reconcile these issues, a different analytical approach is warranted. Considering the gastrointestinal complications and documented cardiovascular risks associated with classical NSAIDs like aspirin and ibuprofen (Slomski 2020; Reed et al. 2018), paracetamol has emerged as the preferred first-line analgesic in postoperative oral care protocols. This pharmacological rationale underpins our selection of paracetamol as the principal NSAID for analytical evaluation.

A critical nuance in this field is that the pathogenesis of oral diseases exhibits a mechanistic connection to systemic health, with accumulating evidence supporting bidirectional communication through the oral–gut microbial axis (Tanwar et al. 2023; Zhang et al. 2021a). Recent advances in microbiome research have demonstrated substantial crosstalk between oral and gastrointestinal ecosystems (Kunath et al. 2024; Li et al. 2019).Emerging evidence indicates that gut microbiota dysbiosis frequently coincides with oral microbial community alterations. However, the current experimental limitations persist, as most mechanistic insights derive from animal models, and observational studies in human populations face constraints that impede causal inference (Sato et al. 2021; Kato et al. 2018; Blasco-Baque et al. 2017). These knowledge gaps restrict our capacity to conceptualize the precise mechanistic interplay between oral inflammatory processes and systemic health outcomes.

Adhering to the same principles of randomization found in clinical trials, Mendelian randomization (MR) leverages genetic variants as instrumental variables (IVs) to investigate causal relationships between exposures and disease risk. The random allocation of these variants at conception serves to mitigate confounding biases and reverse causation, providing a robust tool for causal inference. The validity of this approach, however, requires that each genetic instrument satisfies three core assumptions: relevance, independence, and the exclusion restriction criterion. In this study, we apply this powerful framework to dissect the causal pathways linking anti-inflammatory medication use to oral disease risk.

The results of our Mendelian randomization analysis offer a new genetic perspective on the safety and efficacy of some of dentistry's most common pharmacotherapies. While glucocorticoids are invaluable for controlling severe oral inflammation, our finding of a genetically proxied increased risk for acute periodontitis and oral and oropharyngeal cancer warrants clinical consideration regarding their long-term use. Similarly, while paracetamol is a first-line analgesic, its causal association with an increased risk of dental caries presents a novel and unexpected finding that could influence future therapeutic guidelines.

The intricate nexus between inflammation and oral diseases has consistently placed anti-inflammatory treatments at the forefront of clinical attention. These agents are widely utilized to reduce complications and are even associated with potential long-term systemic benefits, including reduced cancer risk. Their therapeutic role, however, is profoundly complex. A critical oversight in much of the existing research is the paradoxical observation that interventions targeting inflammation can, in certain contexts, exacerbate the very condition they aim to treat (Lai et al. 2022; Pyrikova et al. 2019; Holland et al. 2019). This reality, combined with the prevalent issue of over-medication in clinical practice, demands a more nuanced approach to treatment planning that acknowledges the multifaceted and sometimes contradictory impact of these common drugs.

In the present study, through MR analysis based on GWAS, we discovered causal relationships between the use of anti-inflammatory drugs and the risk of oral diseases. Our research focused on the use of GCs and NSAIDs and their associations with the risk of oral diseases. The results showed significant associations between both drugs and several oral diseases, which highlights the need for prudent use of these medications in clinical practice. According to our analysis, GCs were causally linked to the occurrence of AP, cellulitis, and OOC, whereas NSAIDs showed a protective effect on AP and a promoting effect on OOC, cellulitis.

GCs are widely used, and while previous reports have suggested that they have a suppressive effect on periodontitis, recent studies have shown that GCs may actually promote AP (Baumeister et al. 2023). Concerning the role of GCs in cancer, much research has focused on blood system cancers (such as lymphocytic leukemia, multiple myeloma, and lymphoma) (Cruz-Topete and Cidlowski 2015), as well as on prostate cancer (Hu and Chen 2017), where GCs have a significant inducing effect on tumor cell death. Many studies have concentrated on estrogen receptor alpha (ERα) and found that GCs might inhibit ERα-target genes involved in cell proliferation, thereby blocking tumor growth. For example, in breast cancer, GCs inhibit tumors in ERα-positive cancers, but they support the growth and metastasis of ERα-negative breast cancer cells and exacerbate clinical invasiveness (Pan et al. 2011; West et al. 2018; Abduljabbar et al. 2015). More recently, studies have also suggested that activation of glucocorticoid receptors increases tumor heterogeneity and metastatic potential (Obradovic et al. 2019), promoting cancer progression. In the context of endometrial cancer, both GCs and ERα promote disease progression and metastasis (Vahrenkamp et al. 2018). Clinical and basic research has also demonstrated that GCs promote the development and progression of OOC (Azher et al. 2016; Wang et al. 2023b). GCs, as anti-inflammatory agents, are sometimes used in patients with oral space infections. A report described a patient with oral maxillofacial space infections who had been on long-term oral GCs and immunosuppressive drugs for antibody-associated vasculitis. After discontinuing immunosuppressants and reducing the glucocorticoid dosage, the patient showed rapid improvement. This study did not analyze the causes and therapeutic measures in detail, but our findings suggest that GCs may be a risk factor for cellulitis, offering another perspective on this issue.

The protective role of NSAIDs in AP has been widely acknowledged. Both clinical cohort studies and basic experiments have demonstrated the excellent effect of NSAIDs in inhibiting periodontitis progression, and they are commonly used in clinical settings for this purpose. Our study, from a genetic perspective, confirmed the protective effect of NSAIDs on acute periodontitis and also verified a causal relationship between NSAIDs and the inhibition of its progression. NSAIDs are more broadly used in clinical practice, particularly in managing pain in conditions like pulpitis. However, the effect of NSAIDs on oral diseases' progression, particularly OOC, has received a limited attention. Several case–control studies have concluded that long-term use of NSAIDs offers protection against oral diseases and OOC incidence (Ding et al. 2003), with experimental studies also supporting this protective effect (Lin et al. 2002). However, other research suggests that the use of non-low-dose aspirin increases the risk of oropharyngeal squamous cell carcinoma (Rosenquist et al. 2005), which the authors attribute to a false association driven by self-medication for early symptoms of cancer. For example, Pandeya et al. found that the protective effect of NSAIDs on squamous cell carcinoma was minimal and of value only for high-risk patients (Pandeya et al. 1951). Our study, however, found a causal relationship between the use of NSAIDs and the promotion of OOC development, providing a new angle for subsequent studies. Furthermore, we observed a shared target between NSAIDs and the commonly used anticancer drug methotrexate in the MR analysis. Notably, methotrexate is also used in the treatment of osteoarthritis due to its anti-inflammatory properties, which offers another perspective for examining the role of anti-inflammatory drugs in cancer progression (Gao et al. 2021). Although some studies have indicated that NSAIDs have certain antimicrobial effects (Ferrer-Luque et al. 2023), few have focused on the effects of NSAIDs on the progression of DC. In our study, we have inferred from a genetic perspective that NSAIDs have a causal relationship with the progression of DC. Future research could delve deeper into the mechanism of actions underlying the association between NSAIDs and DC. We also identified NSAIDs as a risk factor for PAP. Some literature reported that the use of NSAIDs could promote the recruitment of mononuclear inflammatory cells to the pulp and periapical regions under inflammatory conditions, which may even exacerbate surrounding bone resorption (Ribeiro-Santos et al. 2021), a finding that aligns with our conclusions.

In the present study, we observed that anti-inflammatory drugs influenced disease progression by altering the abundance of gut microbiota. The oral-gut axis, which includes the mouth and the gut, as the first and last sections of the human digestive tract, are interconnected. Oral microorganisms can spread to the gut, and gut microbiota dysbiosis can lead to chronic inflammation in other parts of the body, which in turn may affect oral microbiota. The causal relationship between these factors is often difficult to determine. Mediation analysis revealed the role of gut microbiota in the association of expression levels of TNFAIP6 and HSPA5 with risk of OOC, suggesting that anti-inflammatory drugs may reduce the expression of HSPA5 and TNFAIP6. When HSPA5 expression is low, the abundance of Verrucomicrobia, Eubacterium ventriosum, and Sellimonas decreases, and the low abundance of Verrucomicrobia leads to an increased OOC risk. Some studies have shown that prednisone use significantly increases Verrucomicrobia (Lima et al. 2022). It has also been reported that conventional treatments for oral squamous cell carcinoma can enhance immune function, resulting in increased abundance of Verrucomicrobia, which is consistent with our second-step MR results (Qian et al. 2022; Ginwala et al. 2021). Our study also found that reduced abundance of Eubacterium ventriosum and SellimonasRoseburia weakened the protective effect of HSPA5 on OOC risk. This is consistent with other studies, which showed that Eubacterium ventriosum and SellimonasRoseburia were often enriched in the gut microbiota of cancer patients (Tonneau et al. 2022a, 2022b; LiYa et al. 2024). We observed that when TNFAIP6 expression was low, Fusicatenibacter abundance decreased and Turicibacter abundance increased, consistent with previous research (Lu et al. 2023; He et al. 2021; Zhang et al. 2021b; Hamada et al. 2023; Zhong et al. 2022; Jeong et al. 2020), both of which are risk factors for OOC, where increased abundance of Turicibacter enhanced OOC risk, and the decreased abundance of Fusicatenibacter weakened the effect of TNFAIP6 on OOC risk.

Similarly, we also found that gut microbiota played a role in the relationship between CCND1 expression and the risks of AP and DC. Anti-inflammatory drugs may reduce CCND1 expression, and when HSPA5 is low, the abundance of Eubacterium coprostanoligenes and Rikenellaceae decreases, while the abundance of Holdemania increases. In our study, we found that Eubacterium coprostanoligenes was a protective factor for AP, while Rikenellaceae and Holdemania were protective factors for DC. There is limited research on gut microbiota in oral disease patients, and only a small amount of evidence is available. It has been found that Eubacterium coprostanoligenes produced butyrate, and supplementation with butyrate-producing bacteria could improve blood glucose control in diabetic patients and animals. Since hyperglycemia can lead to periodontal disease, this may explain why reduced abundance of Eubacterium coprostanoligenes strengthens the effect of CCND1 on AP risk (Li et al. 2021), while the reduced abundance of SellimonasRoseburia weakened the effect of HSPA5 on OOC risk.

Our study has several notable advantages. A primary strength is the use of a MR design, which inherently avoids common epidemiological biases such as selection bias, recall bias, and confounding factors. In comparison to randomized controlled trials, MR provides a simpler and more direct means of investigating causality on a large scale. A second advantage is that our research complements clinical trial evidence from a genetic perspective, presenting novel findings such as the potential causal link between anti-inflammatory drugs and OOC. Finally, the reliability of all our findings was ensured through the application of stringent statistical standards.

However, our study inevitably has some limitations: First, the GWAS databases used in our study are from European populations, and it is unclear whether the results can be generalized to other ethnic groups. Second, we did not categorize the time and method of drug use, and only considered the causal relationship between the exposure factor (drug use) and the outcome. We also did not account for the effects of other interventions, and since these drugs are rarely used in large quantities over extended periods, there may be an overestimation of the effect of anti-inflammatory drugs on oral diseases. Third, we only included anti-inflammatory drug target genes commonly used in the oral cavity. Lastly, there are unavoidable weaknesses in the MR analysis, in which epigenetic issues such as genomic imprinting, maternal effects, and gene silencing may introduce bias (Li et al. 2024).

In the present study, we investigated and found potential associations between the use of anti-inflammatory drugs (GCs and NSAIDs) and risk of certain oral diseases, including acute periodontitis, oral and oropharyngeal cancer, cellulitis, disease of pulp and periapical tissues, and dental caries.

Below is the link to the electronic supplementary material. Supplementary file1 (XLSX 48 KB)