Immunohistochemical localization of Toll‐like receptors 1–10 in periodontitis

Background/aim: In periodontitis, bacteria and pathogen‐associated molecular patterns are sensed by Toll‐like receptors (TLRs), which initiate intracellular signaling cascades that may lead to host inflammation. In this study, the expression and distribution of TLRs (TLR‐1 to TLR‐10) were immunohistochemically detected in gingival epithelium and connective tissue. Methods: Immunohistochemistry was used for the localization of TLRs in gingival tissue samples from 10 patients with chronic periodontitis and 10 healthy controls; these samples were obtained during routine periodontal flap operations and during extraction operations performed for retained wisdom teeth, respectively. For the evaluation, epithelial layers were stratified to basal, spinous, and superficial layers, and the percentages of TLR‐positive cells were determined. Results: Both healthy and periodontitis gingival tissues expressed all TLRs except TLR‐10. In patients with periodontitis, epithelial cells showed increased TLR expression towards the basal layer. Healthy controls showed more variable cellular TLR expression and distribution between the layers of epithelium. In the connective tissue, consistently higher TLR expression was found within the periodontitis group compared to the healthy group. Conclusions: For the first time, the cellular expression and distribution of TLR‐1 to TLR‐10 have been studied in periodontitis, indicating that TLR‐1 to TLR‐9 are differentially expressed both in connective tissue and epithelial layers. Except for TLR‐7 and TLR‐8, all the other TLRs showed statistically significant differences between patients with periodontitis and healthy controls, suggesting their involvement in the pathogenesis of periodontitis.     

Innate Immune Receptor Expression in Peri‐Implant Tissues of Patients With Different Susceptibility to Periodontal Diseases

Background: Although inflammation mediates the pathogenesis of periodontal diseases, the effects of innate immune responses on implant therapies have not been evaluated. Innate immune receptors, including toll‐like‐receptors (TLRs) and the receptor for advanced glycated end‐products (RAGE), are upregulated within inflamed gingiva and are responsible for initiation of detrimental host responses. The aim of this study is to compare the expression of TLR2, TLR4, and RAGE in gingival tissues from participants susceptible to periodontitis and participants not susceptible to periodontitis before and after implant therapy. Methods: Periodontally healthy participants received implant therapy for non‐periodontal edentulism. Participants susceptible to periodontitis were diagnosed with chronic periodontitis prior to implant therapy. Gingival biopsies were collected from edentulous ridges before implant installation and from peri‐implant mucosa 2 months after treatment. Histology, real‐time PCR, and Western blot were used to evaluate levels of inflammatory infiltrate, TLR2, TLR4, and RAGE expression. Results: Before implant therapy, elevated levels of RAGE were detected in gingival tissues from participants susceptible to periodontitis when compared to those from participants with healthy periodontiums, whereas no differences in the expression of TLR2 or TLR4 were detected. After implant therapy, there was an upregulation of RAGE and TLR4 levels that coincided with a downregulation of TLR2 levels in biopsies from participants susceptible to periodontitis. Levels of RAGE and TLR4 remained unchanged in biopsies from participants with healthy periodontiums, whereas TLR2 levels were significantly upregulated. Histologically, post‐implant biopsies from participants susceptible to periodontitis displayed higher levels of inflammatory infiltrate. Conclusion: Elevated levels of inflammatory potential were found after implant therapy in participants susceptible to periodontitis.     

Expression of transient receptor potential vanilloid receptor 1 and toll-like receptor 4 in aggressive periodontitis and in chronic periodontitis

Öztürk A, Y?ld?z L. Expression of transient receptor potential vanilloid receptor 1 and toll‐like receptor‐4 in aggressive periodontitis and in chronic periodontitis. J Periodont Res 2011; 46: 475–482. © 2011 John Wiley & Sons A/S Background and Objective: The objective of the present study was to evaluate the expression and the distribution of the transient receptor potential vanilloid receptor 1 (TRPV1) and of toll‐like receptor 4 (TLR4) in tissue samples from patients with periodontal disease (aggressive periodontitis and chronic periodontitis) and from healthy controls. Material and Methods: Ten tissue samples from each disease group (aggressive periodontitis and chronic periodontitis) and from healthy subjects were obtained during routine oral surgical procedures. Subgingival specimens were collected from sites with advanced loss of support (probing depth > 5 mm) and specimens from the corresponding healthy controls were obtained during tooth extraction for orthodontic reasons or following surgical extraction of an impacted third molar. The distribution of TRPV1 and TLR4 receptors in human gingival tissue was studied by immunohistochemistry. Results: Both TLR4 and TRPV1 were detected in gingival tissues from healthy subjects, and from patients with chronic periodontitis and aggressive periodontitis, particularly in gingival keratinocytes, fibroblasts, inflammatory cells and the endothelial lining of capillaries in connective tissues. Histologic examination of the samples from healthy controls disclosed that clinically healthy gingiva does not correspond to histologically healthy gingiva. Subsequently, these samples were redesignated as gingivitis samples. TRPV1 was down‐regulated in all cell types in samples obtained from patients with chronic periodontitis compared to samples obtained from patients with gingivitis, whereas TLR4 was down‐regulated only in the epithelium and in gingival fibroblasts. In contrast, the levels of these markers in patients with aggressive periodontitis were similar to those in healthy patients. Conclusion: Local expression of TRPV1 and TLR4 in gingival tissues may contribute to both physiological and pathological processes in the periodontium. Our data suggest that TRPV1 and TLR4 may play a role specifically in the pathophysiology of chronic periodontitis.     

Immunohistochemical localization of Toll-like receptors 1-10 in periodontitis

Background/aim:  In periodontitis, bacteria and pathogen-associated molecular patterns are sensed by Toll-like receptors (TLRs), which initiate intracellular signaling cascades that may lead to host inflammation. In this study, the expression and distribution of TLRs (TLR-1 to TLR-10) were immunohistochemically detected in gingival epithelium and connective tissue.
Methods:  Immunohistochemistry was used for the localization of TLRs in gingival tissue samples from 10 patients with chronic periodontitis and 10 healthy controls; these samples were obtained during routine periodontal flap operations and during extraction operations performed for retained wisdom teeth, respectively. For the evaluation, epithelial layers were stratified to basal, spinous, and superficial layers, and the percentages of TLR-positive cells were determined.
Results:  Both healthy and periodontitis gingival tissues expressed all TLRs except TLR-10. In patients with periodontitis, epithelial cells showed increased TLR expression towards the basal layer. Healthy controls showed more variable cellular TLR expression and distribution between the layers of epithelium. In the connective tissue, consistently higher TLR expression was found within the periodontitis group compared to the healthy group.
Conclusions:  For the first time, the cellular expression and distribution of TLR-1 to TLR-10 have been studied in periodontitis, indicating that TLR-1 to TLR-9 are differentially expressed both in connective tissue and epithelial layers. Except for TLR-7 and TLR-8, all the other TLRs showed statistically significant differences between patients with periodontitis and healthy controls, suggesting their involvement in the pathogenesis of periodontitis.     

Salivary and plasma levels of Toll-like receptor 2 and Toll-like receptor 4 in chronic periodontitis

Background: This cross‐sectional study was planned to investigate whether patients with chronic periodontitis exhibit different salivary or plasma concentrations of Toll‐like receptor (TLR) 2 and TLR4 compared to subjects who are clinically healthy. Methods: Whole saliva and plasma samples were obtained and full‐mouth clinical periodontal measurements were recorded from 22 otherwise healthy patients with chronic periodontitis and 21 systemically and periodontally healthy control subjects. Salivary and plasma TLR2 and TLR4 levels were determined by enzyme‐linked immunoassays. Data were tested statistically using Mann‐Whitney U test. Results: The healthy group exhibited significantly lower values in all clinical measurements (P <0.001). The salivary TLR2 levels were similar in the two study groups (P >0.05). The patients with chronic periodontitis exhibited significantly higher salivary TLR4 (P <0.01) and plasma TLR2 and TLR4 levels (P <0.05). Conclusion: The present findings support a hypothesis that inflammation increases expression of TLRs which leads to an increased detection of TLRs in saliva and plasma, which could be useful as a diagnostic test for periodontal diseases.     

In vivo expression of Toll‐like receptor 2, Toll‐like receptor 4, CSF2 and LY64 in Chinese chronic periodontitis patients

Oral Diseases (2010) 16 , 343–350 Objective: Toll‐like receptors (TLRs) are the essential components in the innate and adaptive immune systems. Colony stimulating factor 2 (CSF2) is a cytokine that may prevent endotoxin tolerance, and LY64 has the ability to interfere with the recognition of bacteria via TLR4. The aim of this study was to explore the in vivo expressions of TLR2, TLR4, CSF2 and LY64 in Chinese chronic periodontitis patients. Methods: Gingival biopsies were collected from 24 chronic periodontitis patients and 19 healthy controls. The gene expression profiles of TLR2, TLR4, CSF2 and LY64 were investigated by real‐time polymerase chain reaction, and the protein expressions of TLR2 and TLR4 were detected by immunohistochemistry. In addition, the levels of CSF2 in gingival crevicular fluid (GCF) were determined by ELISA. Results: The higher mRNA expressions of TLR2, TLR4 and CSF2, and the lower mRNA expression of LY64 were detected in chronic periodontitis patients. And the increased protein expressions of TLR2 and TLR4 were confirmed by immunohistochemistry. In addition, the increase of total amount of CSF2 in GCF was observed in chronic periodontitis patients. Conclusions: Our results suggest that TLR2 and TLR4 may play a role in periodontal pathogenesis. In addition, CSF2 and LY64 may contribute to the regulation of inflammatory response and maintaining periodontal homeostasis.     

Quantitative messenger RNA expression of Toll‐like receptors and interferon‐α1 in gingivitis and periodontitis

Introduction: In addition to bacteria, viruses have been reportedly implicated in periodontitis. However, the available data are confined to Toll‐like receptor 2 (TLR2) and TLR4, which recognize bacterial products in periodontitis. In the present study, we investigated the expression levels of TLR5, ‐7, and ‐9 messenger RNAs (mRNAs) in addition to those of TLR2 and ‐4, and compared gingivitis and periodontitis. Interferon‐α1 (IFN‐α1), which is important for the antiviral response, was also compared. Methods: Gene expression was analyzed using quantitative real‐time polymerase chain reaction for 59 periodontitis and 27 gingivitis tissue samples together with viral serology in some patients. The presence of plasmacytoid dendritic cells (pDCs), a robust producer of IFN‐α, was immunohistochemically analyzed in an additional seven periodontitis and two gingivitis specimens. Results: The expression levels of TLR2, ‐4, ‐7, and ‐9 were significantly higher in periodontitis lesions than gingivitis lesions. The expression level of TLR5 was comparable to levels of TLR2 and ‐4; however, no significant difference was found between gingivitis and periodontitis. Although the expression of IFN‐α1 mRNA was higher in periodontitis lesions compared with gingivitis lesions, the level was quite low. Only a few pDCs were found in some periodontitis specimens. No difference was found for antibody‐positivity between gingivitis and periodontitis. Conclusion: This is the first study to show that a variety of TLRs are up‐regulated in periodontitis lesions compared with gingivitis lesions, suggesting that diverse microbial and possibly viral antigens are involved in the pathogenic mechanisms for periodontal diseases. However, the ligands recognized by the various TLRs in periodontal lesions remain to be determined.     

Combined effects of hydrogen sulfide and lipopolysaccharide on osteoclast differentiation in rats

Background: Lipopolysaccharide (LPS) stimulates osteoclast differentiation through toll‐like receptors (TLRs) 2 and 4, and hydrogen sulfide (H₂S) induces osteoclast differentiation. If H₂S activates TLRs, H₂S may enhance the effects of LPS on osteoclast differentiation. The purpose of the present study is to examine the combined effects of sodium hydrogen sulfide (NaHS, an H₂S donor drug) and LPS on osteoclast differentiation and TLR expression in rat periodontal tissue. Methods: Twenty‐eight male Wistar rats (8 weeks old) were divided into four groups (n = 7 per group): a control (no treatment) group and three experimental groups (NaHS group, LPS group, and a combination [NaHS + LPS] group). At 1 day after topical application of NaHS and/or Porphyromonas gingivalis LPS into the gingival sulcus of first molars, the number of tartrate‐resistant acid phosphate (TRAP)‐positive osteoclasts in the periodontal tissue was counted. Expression of TLR2 and TLR4 mRNAs and proteins in the gingival was also assessed. Results: The number of TRAP‐positive osteoclasts was significantly higher in the combination group than in any other group (P <0.01). The combination group had 11.0‐fold higher TLR4 mRNA levels than the control group. TLR4 protein levels were also higher in the combination group than in the NaHS or LPS group. However, the TLR2 mRNA and protein levels were not significantly different in the combination group and the LPS group. Conclusion: In rat periodontal tissue, NaHS and LPS had an additive effect on osteoclast differentiation through activation of the TLR4 pathway but not the TLR2 pathway.     

MMP-2在吸烟牙周炎患者牙龈组织中的表达

目的:从MMP-2的酶活性和mRNA水平探讨吸烟与牙周病的关系。方法:利用明胶酶活性分析(zymog-raphy)和RT-PCR方法,分别检测6例吸烟牙周病、6例不吸烟牙周病、6例吸烟正常人、6例不吸烟正常人的牙龈组织中MMP-2的酶活性和mRNA表达。结果:吸烟和牙周病牙龈组织中MMP-2酶活性都较正常组有增加,但吸烟牙周病组的MMP-2的酶活性与吸烟无牙周病组和不吸烟牙周病组有明显差异(P<0.01),吸烟牙周病患者牙周组织中MMP-2的mRNA水平较正常组明显增加(P<0.01)。结论:MMP-2在吸烟牙周炎牙周组织的破坏中起重要作用。     

Periodontal ligament and gingival fibroblasts from periodontitis patients are more active in interaction with Porphyromonas gingivalis

Scheres N, Laine ML, Sipos PM, Bosch‐Tijhof CJ, Crielaard W, de Vries TJ, Everts V. Periodontal ligament and gingival fibroblasts from periodontitis patients are more active in interaction withPorphyromonas gingivalis. J Periodont Res 2011; 46: 407–416. © 2011 John Wiley & Sons A/S Background and Objective: Inflammatory responses of host cells to oral pathogenic bacteria, such as Porphyromonas gingivalis, are crucial in the development of periodontitis. Host cells, such as periodontal ligament and gingival fibroblasts, from periodontitis patients may respond to P. gingivalis in a different manner compared with cells from healthy persons. The aim of this study was to investigate inflammatory responses to viable P. gingivalis by periodontal ligament and gingival fibroblasts from periodontitis patients and healthy control subjects. Material and Methods: Primary periodontal ligament and gingival fibroblasts from periodontitis patients (n = 14) and healthy control subjects (n = 8) were challenged in vitro with viable P. gingivalis. Gene expression of Toll‐like receptors (TLRs) 1, 2, 4, 6, 7 and 9, CD14, nuclear factor‐κB1 and its putative inhibitor NF‐κB inhibitor‐like protein 1, and of interleukin‐1β, interleukin‐6, interleukin‐8, tumour necrosis factor‐α, monocyte chemotactic protein‐1 and regulated upon activation, normal T‐cel expressed, and secreted, were assessed by real‐time PCR. Results: Periodontal ligament fibroblasts from periodontitis patients had a higher mRNA expression of TLR1, TLR4, TLR7 and CD14, and a lower expression of NFKBIL1, both before and after P. gingivalis challenge. In contrast, gingival fibroblasts from periodontitis patients had stronger induction of TLR1, TLR2 and TLR7 by P. gingivalis. Cytokine responses were not different between patients and control subjects. Interestingly, periodontal ligament, but not gingival, fibroblasts from P. gingivalis culture‐positive persons responded more strongly to P. gingivalis than periodontal ligament fibroblasts from P. gingivalis‐negative persons. Conclusion: Periodontal ligament and gingival fibroblasts respond to P. gingivalis in a different manner and may play different roles in periodontitis. Both subsets of fibroblasts from patients appear more active in interaction with P. gingivalis. Moreover, periodontal ligament fibroblasts from P. gingivalis‐positive donors are more responsive to an in vitro P. gingivalis challenge.     

Role of receptors of advanced glycation end‐products (RAGE) in type 2 diabetic and non‐diabetic individuals with chronic periodontal disease: an immunohistochemical study

Aim: The relationship between diabetes and periodontal disease is well established. It has been shown that advanced glycation end‐products might exert noxious effects on several tissues of the body through its receptor. Evidence for the role of receptors of advanced glycation end‐products in periodontal disease for diabetes is limited, and their presence in human gingival tissues has been demonstrated in few studies. In this study, we demonstrate the presence of receptors of advanced glycation end‐products in patients with chronic periodontitis, with and without type 2 diabetes. Methods: Gingival biopsies from 19 patients with both type 2 diabetes and chronic periodontitis, and 18 healthy controls with chronic periodontitis, were immunohistochemically stained for receptors of advanced glycation end‐products. Results: On immunohistochemical analysis, positive staining for receptors of advanced glycation end‐products was seen in the endothelium and the basal and spinous layers of the inflamed gingival epithelium in both type 2 diabetes and non‐diabetes tissue, with a statistically‐significant difference between both groups (P < 0.05). Conclusions: There was a significant difference in receptors of advanced glycation end‐product immune reactivity between both groups. Receptors of advanced glycation end‐product increase in type 2 diabetes gingival tissue might indicate possible involvement of this receptor in periodontal destruction in individuals with type 2 diabetes.     

Increased Nucleic Acid Receptor Expression in Chronic Periodontitis

Background: Nucleic acid sensing has emerged as one of the important components of the immune system triggering inflammation. The aim of this study is to determine the expression of bacterial DNA sensors, including Toll‐like receptor 9 (TLR‐9), DNA‐dependent activator of interferon‐regulatory factors (DAI), and absent in melanoma 2 (AIM2) in chronic periodontitis (CP versus healthy) (H) tissues. Methods: Thirty‐five CP and 27 H gingival biopsies were included. Real‐time quantitative polymerase chain reaction was performed to determine mRNA levels of AIM2, DAI, and TLRs (TLR‐1 through TLR‐9). The difference in gene expression for each sensor between CP and H tissues was calculated using analysis of covariance. The Spearman test was used to determine correlations among innate receptors. The expression of TLR‐9, AIM2, and DAI in gingival tissues was further confirmed using immunohistochemistry. Results: The present results reveal statistically significant upregulation of TLR‐9 (P <0.006), DAI (P <0.001), and TLR‐8 (P <0.01) in CP tissues compared to H sites. Although mRNA expression was not changed significantly between groups for other receptors, the present results reveal significant correlations between receptors (P <0.05), suggesting that cooperation between multiple components of the host immune system may influence the overall response. Immunohistochemistry further confirmed expression of TLR‐9, AIM2, and DAI in gingival tissues. Conclusions: This study highlights a possible role for nucleic acid receptors in periodontal inflammation. Future investigations will determine whether cytoplasmic receptors and their ligands can be targeted to improve clinical outcomes in periodontitis.     

Quantitative messenger RNA expression of Toll-like receptors and interferon-alpha1 in gingivitis and periodontitis

INTRODUCTION: In addition to bacteria, viruses have been reportedly implicated in periodontitis. However, the available data are confined to Toll-like receptor 2 (TLR2) and TLR4, which recognize bacterial products in periodontitis. In the present study, we investigated the expression levels of TLR5, -7, and -9 messenger RNAs (mRNAs) in addition to those of TLR2 and -4, and compared gingivitis and periodontitis. Interferon-alpha1 (IFN-alpha1), which is important for the antiviral response, was also compared. METHODS: Gene expression was analyzed using quantitative real-time polymerase chain reaction for 59 periodontitis and 27 gingivitis tissue samples together with viral serology in some patients. The presence of plasmacytoid dendritic cells (pDCs), a robust producer of IFN-alpha, was immunohistochemically analyzed in an additional seven periodontitis and two gingivitis specimens. RESULTS: The expression levels of TLR2, -4, -7, and -9 were significantly higher in periodontitis lesions than gingivitis lesions. The expression level of TLR5 was comparable to levels of TLR2 and -4; however, no significant difference was found between gingivitis and periodontitis. Although the expression of IFN-alpha1 mRNA was higher in periodontitis lesions compared with gingivitis lesions, the level was quite low. Only a few pDCs were found in some periodontitis specimens. No difference was found for antibody-positivity between gingivitis and periodontitis. CONCLUSION: This is the first study to show that a variety of TLRs are up-regulated in periodontitis lesions compared with gingivitis lesions, suggesting that diverse microbial and possibly viral antigens are involved in the pathogenic mechanisms for periodontal diseases. However, the ligands recognized by the various TLRs in periodontal lesions remain to be determined.     

Odanacatib,A Cathepsin K‐Specific Inhibitor,Inhibits Inflammation and Bone Loss Caused by Periodontal Diseases

Background: Periodontitis is a bacteria‐induced inflammatory disease mainly affecting periodontal tissues, leading to periodontal inflammation, bone breakdown, and loss of the tooth. The main obstacle for treating periodontitis effectively is the difficulty in finding a target that can inhibit bone loss and inflammation simultaneously. Recent studies showed that cathepsin K (CTSK) might have functions in the immune system besides its role in osteoclasts. Thus, targeting CTSK would have a potential therapeutic effect in both the bone system and the immune system during the progression of periodontitis. Methods: In the current study, a small molecular inhibitor (odanacatib [ODN]) is explored to inhibit the function of CTSK in a bacteria‐induced periodontitis mouse model. Results: The application of ODN decreased the number of osteoclasts, macrophages, and T cells, as well as the expression of Toll‐like receptors (TLRs) in the periodontitis lesion area. Furthermore, lack of CTSK inhibited the expression of TLR4, TLR5, and TLR9 and their downstream cytokine signaling in the gingival epithelial cells in periodontitis lesions, demonstrating that the innate immune response was inhibited in periodontitis. Conclusion: The present results show that inhibition of CTSK can prevent bone loss and the immune response during the progression of periodontitis, indicating that CTSK is a promising target for treating inflammatory diseases such as periodontitis by affecting both osteoclasts and the immune system.     

Toll‐like receptors 2 and 5 in human gingival epithelial cells co‐operate with T‐cell cytokine interleukin‐17

Background/aim: Periodontitis begins as the result of perturbation of the gingival epithelial cells caused by subgingival bacteria interacting with the epithelial cells via pattern recognition receptors. Toll‐like receptors (TLRs) have been shown to play an important role in the recognition of periodontal pathogens so we have studied the interaction of TLR ligands with TLR2 and TLR5 for cytokine production in the cultures of gingival epithelial cells. Methods: Immunohistochemistry was used for the localization of TLR2 and TLR5 in tissue specimens. Enzyme‐linked immunosorbent assays were performed to detect the levels of interleukin‐1β (IL‐1β) and tumor necrosis factor‐α (TNF‐α), released from gingival epithelial cell cultures following stimulation with TLR ligand alone or in combination with IL‐17. Results: Both TLR2 and TLR5 were increased in periodontitis (2128 ± 159 vs. 449 ± 59 and 2456 ± 297 vs. 679 ± 103, respectively, P < 0.001) including gingival epithelial cells that stained strongly. Cultured gingival epithelial cells stimulated with their respective ligands (HKLM, a TLR2 ligand that is also found in Porphyromonas gingivalis, and flagellin, a TLR5 ligand that is also found in Treponema denticola) produced both IL‐1β and TNF‐α. To mimic T‐cell help, IL‐17 was added. This further greatly enhanced TLR ligand‐induced IL‐1β (P < 0.001) and TNF‐α (P < 0.01) production. Conclusions: These findings show how pathogen‐associated molecular patterns, shared by many different periodontopathogenic bacteria, stimulate the resident gingival epithelial cells to inflammatory responses in a TLR‐dependent manner. This stimulation may be particularly strong in periodontitis and when T helper type 17 cells provide T‐cell help in intercellular cooperation.     

Prediabetes Enhances Periodontal Inflammation Consistent With Activation of Toll‐Like Receptor–Mediated Nuclear Factor‐κB Pathway in Rats

Background: Clinical studies have showed that prediabetes (preDM) is a predisposing factor for periodontitis. However, the pathogenic mechanism involved is unclear. Because it is known that the activation of Toll‐like receptor (TLR)‐mediated nuclear factor‐kappa B (NF‐κB) signaling pathway plays a crucial role in periodontitis, it is hypothesized that preDM enhances periodontal inflammation by activation of the TLR‐mediated NF‐κB pathway. Methods: In this study, a preDM rat model is established by feeding a high‐fat diet (HFD). HFD‐induced rats with preDM (n = 7) and normal chow–fed rats (n = 7) were studied. The animal model was characterized in terms of body weight and the glycemic and insulinemic profiles. The following parameters were assessed to evaluate possible early periodontal alterations and underlying mechanisms: 1) histology analysis of periodontal tissue; and 2) serum and mRNA levels and/or the tissue protein expression of TLRs, myeloid differentiation factor 88 (MyD88), tumor necrosis factor (TNF) receptor–associated factor 6 (TRAF6), NF‐κB, cytokines, advanced glucose ends (AGEs), and free fatty acids (FFAs). Results: Rats with preDM presented higher expression of TLR2 and TLR4 in periodontal tissue in the HFD group compared with the control group. The TLR2 and TLR4 was mostly expressed in gingiva, and TLR4 was expressed in periodontal ligament in rats. Furthermore, the MyD88 and TRAF6 protein levels were significantly increased in gingiva in rats with preDM compared with normal rats. The activity of NF‐κB signals was higher in rats with preDM than in normal rats. Regarding cytokines expression, the TNF‐α protein levels and interleukin‐1β mRNA levels were significantly increased in the HFD group compared with the control group. In the serum, AGEs levels were significantly increased in the rats with preDM. Mean FFAs concentrations were increased in rats with preDM compared with normal rats, but it did not reach statistical significance. Conclusion: In rats with preDM, TLR2 and TLR4 gene and protein levels were higher in periodontal tissue, and the activation of NF‐κB may, through TLRs/MyD88, cause more cytokine secretion, which is associated with the onset or development of periodontal disease.