Advanced glycation end products (AGEs) and their receptor (RAGE) induce apoptosis of periodontal ligament fibroblasts

Advanced glycation end products impair the repair of injured tendon: a study in rats

BACKGROUND

The AGEs levels in tissues of diabetics and elderly tend to be higher than in normal individuals. This study aims to determine the effects of AGEs on Achilles tendon repair.

MATERIALS AND METHODS

Thirty-six male eight-week-old Sprague Dawley rats were selected in this study. The rats were randomly divided into two experimental groups and a control group after the transection of the Achilles tendon. During the tendon repair, the experimental groups were injected around the Achilles tendon with 350mmol/L (low dose group) and 1000mmol/L (high dose group) D-ribose 0.2 ml respectively to increase the AGEs level, while in the control group were given the same amount of PBS. The injections were given twice a week for six weeks. Collagen-I, TNF-α, and IL-6 expression in the healed Achilles tendon was assessed. Additionally, macroscopic, pathological, and biomechanical evaluations of Achilles tendon repair were conducted.

RESULTS

The repaired Achilles tendons in the high dose group showed severe swelling and distinctive adhesions. The histological score went up with the increase of the AGEs in the Achilles tendon (p<0.001). TNF- α and IL-6 in the Achilles tendon increased (p<0.001, p<0.001), and the production of collagen-I decreased with the accumulation of AGEs in the repaired Achilles tendon (p<0.001). The tensile strength of Achilles tendon in the high dose group was impaired significantly.

CONCLUSION

In current study, the compromised tendon repair model induced by AGEs was successfully established in rat. The study demonstrated that AGEs significantly impair Achilles tendon repair.

Pioglitazone Antagonized the Effects of Advanced Glycation End Products on Achilles Tendon Healing and Improved the Recovery of Tendon Biomechanical Properties

Purpose

Advanced glycation end products (AGEs) often accumulate in the Achilles tendon during the course of diabetes. This study aims to determine the impact of AGEs on tendon repair and explore the role of pioglitazone in mitigating this impact.

Methods

Forty-eight male 8 week-old Sprague Dawley rats were selected in this study. After transection of Achilles tendon, the rats were randomly divided into four groups. The Achilles tendons of rats were injected with 1000 mmol/L D-ribose to elevate the content of AGEs within the tendons in two groups, the remaining two groups received injections of phosphate buffered saline (PBS) solution. Subsequently, the first two groups were respectively received oral administration of pioglitazone (20 mg/kg/day) and PBS. The remaining two groups were given the same treatment. The expression of the collagen-I, TNF-α, IL-6 of the repaired tendon were detected. The macroscopic, pathologic and biomechanical aspects of tendon healing were also evaluated.

Results

AGEs accumulation in tendon during the healing process increases the expression of inflammatory factors such as TNF-α and IL-6, leading to insufficient synthesis of collagen-I and delayed recovery of the tendon's tensile strength. Pioglitazone significantly attenuated the damage caused by AGEs to the tendon healing process, effectively improving the recovery of tendon tensile strength. Pioglitazone could not inhibit the generation of AGEs in the tissue and also had no impact on the normal healing process of the tendon.

Conclusions

Pioglitazone could prevent the deleterious impact of AGEs on the Achilles tendon healing and improve the biomechanical properties of the tendon.

Relationship Between Diabetes Mellitus and Periodontal/Peri-Implant Disease: A Contemporaneous Review

The prevalence of diabetes mellitus (DM), a major chronic disease and a leading cause of death and disability around the world, is rising. According to the latest data, the global prevalence of DM has increased to 463 million (9.3% of adults) in 2019 and is estimated to reach 700 million by 2045. Periodontal disease, result of periodontium inflammation, is a common, chronic disease and has long been considered one of the complications of DM. Moreover, literature reflects a spectrum of conflicting viewpoints on the effect of diabetic conditions on the implant treatment strategies. The current review aims to update the recent epidemiologic evidence regarding the relationship between DM and periodontal/peri-implant disease, emphasising the effects of glycaemic control on the severity of these diseases and describing the pathobiological mechanisms underlying this association. This review's findings indicate a bidirectional relationship between DM and periodontal/peri-implant disease and that this relationship seems causal, implying that controlling these two diseases might help prevent each other's incidence. Additionally, the severity of periodontal/peri-implant disease is directly related to metabolic control. Although patients with diabetes can obtain implant success similar to those in systemically healthy individuals, an increased risk of peri-implantitis has been reported in DM patients. Therefore, the importance of glycaemic control and maintaining proper oral hygiene cannot be overstated.

NLRP10 promotes AGEs-induced NLRP1 and NLRP3 inflammasome activation via ROS/MAPK/NF-κB signaling in human periodontal ligament cells

Diabetes mellitus (DM), characterized by production and accumulation of advanced glycation end products (AGEs), induces and promotes chronic inflammation in tissues, including periodontal tissue. Increasing amount of epidemiological and experimental evidence demonstrated that more extensive inflammatory reaction and bone resorption occurred in periodontal tissues in diabetic patients with periodontitis, which is speculated to be related to NLRP3 inflammasome. NLRP10 is the only NOD-like receptor protein lacking leucine-rich repeats, suggesting that NLRP10 may be a regulatory protein. The aim of this study was to investigate the regulatory role of NLRP10 on NLRP1 and NLRP3 inflammasome in human periodontal ligament cells (HPDLCs) under AGEs treatment. Expression of NLRP10 in HPDLCs stimulated with 100 ug/mL AGEs for 24 h was observed. Detection of TRIM31 is conducted, and in TRIM31-overexpressed HPDLCs, the interaction between NLRP10 with TRIM31 as well as NLRP10 with ubiquitination were explored by immunoprecipitation. Under AGEs stimulation, the activation of reactive oxidative stress (ROS) and inflammatory signaling pathway (NF-κB, MAPK pathway) was detected by biomedical microscope and western blot (WB), respectively. After stimulation with AGEs for 24 h with or without silencing NLRP10, inflammatory cytokines (IL-6 and IL-1β), NF-κB, MAPK pathway, ROS, and components of inflammasome were assessed. In HPDLCs, we found AGEs induced NLRP10 and inhibited TRIM31. TRIM31 overexpression significantly enhanced interaction between TRIM31 and NLRP10, then induced proteasomal degradation of NLRP10. Moreover, under AGEs stimulation, NLRP10 positively regulates NLRP1, NLRP3 inflammasomes by activating NF-κB, MAPK pathway, and increasing ROS, finally promoting the expression of inflammatory cytokines. Together, we, for the first time, confirmed that NLRP10 could promote inflammatory response induced by AGEs in HPDLCs via activation of NF-κB, and MAPK pathway and increasing ROS.

Programmed cell death of periodontal ligament cells

The periodontal ligament is a crucial tissue that provides support to the periodontium. Situated between the alveolar bone and the tooth root, it consists primarily of fibroblasts, cementoblasts, osteoblasts, osteoclasts, periodontal ligament stem cells (PDLSCs), and epithelial cell rests of Malassez. Fibroblasts, cementoblasts, osteoblasts, and osteoclasts are functionally differentiated cells, whereas PDLSCs are undifferentiated mesenchymal stem cells. The dynamic development of these cells is intricately linked to periodontal changes and homeostasis. Notably, the regulation of programmed cell death facilitates the clearance of necrotic tissue and plays a pivotal role in immune response. However, it also potentially contributes to the loss of periodontal supporting tissues and root resorption. These findings have significant implications for understanding the occurrence and progression of periodontitis, as well as the mechanisms underlying orthodontic root resorption. Further, the regulation of periodontal ligament cell (PDLC) death is influenced by both systemic and local factors. This comprehensive review focuses on recent studies reporting the mechanisms of PDLC death and related factors.

Impact of systemic health on treatment outcomes in endodontics

BACKGROUND

The healing of periapical lesions after root canal treatment (RCT) is not the result of the curative action of the treatment. The process of healing begins with inflammation, and is resolved by the clearance of the immunogen that induces the immune response. Then, the periapical tissue itself carries out the healing of the periapical lesion, by repair or by a combination of repair and regeneration, depending on the host's reparative response working properly. The ultimate objective of RCT is to achieve wound healing by removing the source of bacterial antigens and toxins, allowing chronic inflammatory tissue to become reparative tissue. Some systemic conditions increase the susceptibility of the host to infection or impair the tissue reparative response, maintaining the inflammatory process and periapical bone resorption after RCT. This can cause the failure of RCT and even the need for extraction of the affected tooth.

OBJECTIVE

To analyse the scientific literature on the possible influence of systemic conditions on the treatment outcomes in endodontics, as well as to discuss the biological mechanisms that may be involved.

METHODS

The search was carried out in PubMed, SCOPUS and EMBASE. The inclusion criteria established were original scientific articles reporting data about some systemic condition in relation to treatment outcomes in endodontics, including clinical studies and studies carried out in animal models.

RESULTS

Systemic factors (age, nutrition, stress, hormones, smoking habits), and systemic diseases, such as diabetes, cardiovascular diseases, osteoporosis, HIV infection, inflammatory bowel disease, and others, can influence or interfere in the repair of periapical tissues after RCT.

DISCUSSION

Some of these systemic diseases can alter bone turnover and fibroblast function, preventing or delaying periapical wound healing. Others can alter the microvasculature, reducing nutrients and oxygen supply to periapical tissues. As a result, these systemic conditions can decrease the success rate of RCT and provoke incomplete wound healing (typically granulomatous tissue formation) in the periapical region.

CONCLUSIONS

The results of this narrative review show worse success rate of RCT, with higher percentage of postoperative radiolucent periapical lesions and higher proportion of non-retained teeth (RFT), associated with several systemic conditions, such as smoking habits and diabetes.

Increased expression of advanced glycation endproducts in the gingival crevicular fluid compromises periodontal status in cigarette-smokers and waterpipe users

Background

The aim was to assess the association between levels of advanced glycation endproducts (AGEs) in the gingival crevicular fluid (GCF) and periodontal parameters among cigarette-smokers and waterpipe-users.

Methods

Self-reported cigarette-smokers; waterpipe-users and never-smokers were included. Demographic data was recorded using a questionnaire. Periodontal parameters (plaque index [PI], gingival index [GI], clinical attachment loss [AL], probing depth [PD], and marginal bone loss [MBL]) were assessed in all groups. The GCF samples were collected using standard techniques and assessed for AGEs levels using enzyme-linked immunosorbent assay. Sample-size estimation was done and group-comparisons were done. Correlation between levels of GCF AGEs levels and periodontal parameters was assessed using a logistic regression model. Level of significance was set at P < 0.01.

Results

Eighty-two individuals (28 cigarette-smokers, 28 waterpipe-users and 26 never-smokers) were included. There was no difference in mean ages of all patients. Cigarette-smokers had a smoking history of 5.1 ± 0.2 pack years and waterpipe-users were using waterpipe for 4.4 ± 0.6 years. There was no statistically significant difference in PI, GI, clinical AL, PD and MBL in all groups. Levels of AGEs were significantly higher among cigarette-smokers (P < 0.001) and waterpipe-users (P < 0.001) than never-smokers. There was no significant correlation between levels of GCF AGEs levels and periodontal parameters in all groups.

Conclusion

Clinical periodontal status of individuals with a short history of cigarette-smoking and waterpipe-usage may appear similar to never-smokers. On a molecular level, cigarette-smoking and waterpipe-users express raised levels of AGEs than never-smokers that sirens about the ongoing yet latent periodontal inflammatory process.

Pathogenic Molecular Mechanisms in Periodontitis and Peri-Implantitis: Role of Advanced Glycation End Products

Advanced Glycation End Products (AGEs), the products of the non-enzymatic oxidation of proteins, nucleic acids, and lipids, are accumulated in periodontal tissues under hyperglycemic conditions such as Diabetes Mellitus (DM) and are responsible for sustained periodontal destruction. AGEs mediate their intracellular effects either directly or indirectly through receptor binding (via RAGE) in all types of periodontal ligament cells (osteocytes, gingival fibroblasts, stem cells, epithelial cells), indicating an important target for intervention. In combination with lipopolysaccharides (LPS) from Porphyromonas gingivalis (Pg), the negative impact of AGEs on periodontal tissue is further enhanced and accentuated. In addition, AGE accumulation is evident in peri-implantitis, yet through different underlying molecular mechanisms. Novel therapeutic approaches targeting the effects of AGEs in periodontal ligament cells show beneficial effects in pre-clinical studies. Herein, we provide evidence on the detrimental role of AGE accumulation in oral cavity tissues and their associated signaling pathways in periodontitis and peri-implantitis to further highlight the significance of oral or topical use of AGE blockers or inhibitors along with dental biofilms’ removal and DM regulation in patients’ management.

Advanced Glycation End Products Increase Salivary Gland Hypofunction in d-Galactose-Induced Aging Rats and Its Prevention by Physical Exercise

A declined salivary gland function is commonly observed in elderly people. Advanced glycation end products (AGEs) are believed to contribute to the pathogenesis of aging. Although physical exercise is shown to increase various organ functions in human and experimental models, it is not known whether it has a similar effect in the salivary glands. In the present study, we evaluated the AGEs burden in the salivary gland in the aging process and the protective effect of physical exercise on age-related salivary hypofunction. To accelerate the aging process, rats were peritoneally injected with D-galactose for 6 weeks. Young control rats and d-galactose-induced aging rats in the old group were not exercised. The rats in the physical exercise group ran on a treadmill (12 m/min, 60 min/day, 3 days/week for 6 weeks). The results showed that the salivary flow rate and total protein levels in the saliva of the d-galactose-induced aging rats were reduced compared to those of the young control rats. Circulating AGEs in serum and secreted AGEs in saliva increased with d-galactose-induced aging. AGEs also accumulated in the salivary glands of these aging rats. The salivary gland of aging rats showed increased reactive oxygen species (ROS) generation, loss of acinar cells, and apoptosis compared to young control mice. However, physical exercise suppressed all of these age-related salivary changes. Overall, physical exercise could provide a beneficial option for age-related salivary hypofunction.

A Catecholaldehyde Metabolite of Norepinephrine Induces Myofibroblast Activation and Toxicity via the Receptor for Advanced Glycation Endproducts: Mitigating Role of l-Carnosine

Monoamine oxidase (MAO) is rapidly gaining appreciation for its pathophysiologic role in cardiac injury and failure. Oxidative deamination of norepinephrine by MAO generates H2O2 and the catecholaldehyde 3,4-dihydroxyphenylglycolaldehyde (DOPEGAL), the latter of which is a highly potent and reactive electrophile that has been linked to cardiotoxicity. However, many questions remain as to whether catecholaldehydes regulate basic physiological processes in the myocardium and the pathways involved. Here, we examined the role of MAO-derived oxidative metabolites in mediating the activation of cardiac fibroblasts in response to norepinephrine. In neonatal murine cardiac fibroblasts, norepinephrine increased reactive oxygen species (ROS), accumulation of catechol-modified protein adducts, expression and secretion of collagens I/III, and other markers of profibrotic activation including STAT3 phosphorylation. These effects were attenuated with MAO inhibitors, the aldehyde-scavenging dipeptide l-carnosine, and FPS-ZM1, an antagonist for the receptor for advanced glycation endproducts (RAGE). Interestingly, treatment of cardiac fibroblasts with a low dose (1 μM) of DOPEGAL-modified albumin phenocopied many of the effects of norepinephrine and also induced an increase in RAGE expression. Higher doses (>10 μM) of DOPEGAL-modified albumin were determined to be toxic to cardiac fibroblasts in a RAGE-dependent manner, which was mitigated by l-carnosine. Collectively, these findings suggest that norepinephrine may influence extracellular matrix remodeling via an adrenergic-independent redox pathway in cardiac fibroblasts involving the MAO-mediated generation of ROS, catecholaldehydes, and RAGE. Furthermore, since elevations in the catecholaminergic tone and oxidative stress in heart disease are linked with cardiac fibrosis, this study illustrates novel drug targets that could potentially mitigate this serious disorder.

The effect of streptozotocin induced diabetes on sperm function: a closer look at AGEs, RAGEs, MAPKs and activation of the apoptotic pathway

This study was designed to (1) investigate the possible mechanisms through which diabetes-induced advanced glycation end products (AGEs) and receptor for AGEs (RAGE) activation can affect male reproductive function; and (2) corroborate the interaction of previously established independent pathways. Male albino Wistar rats (14-weeks old) weighing 250-300 g received either a single intraperitoneal injection of streptozotocin (30 mg/kg or 60 mg/kg), represented as STZ30 or STZ60 respectively, or citrate buffer (control). Diabetes mellitus (DM) was confirmed if plasma glucose levels were ≥ 14 mmol/L after 1 week. Animals were sacrificed after 8 weeks of treatment by an overdose of sodium pentobarbital (160 mg/kg body weight). The testes and epididymides were harvested. The testes were used for biochemical and Western blot analysis, while sperm was retrieved from the epididymis and analysed with computer-aided sperm analysis. The blood glucose levels of STZ60 animals were above the cut-off point and hence these animals were regarded as diabetic. Diabetic animals presented with a non-significant increase in AGE and RAGE expression. Diabetic animals showed a significant increase in the expression of cleaved caspase 3 compared to control (p < 0.001), and these animals also presented with an increase in the expression of JNK (p < 0.05), PARP (p = 0.059) and p38 MAPK (p = 0.1). Diabetic animals also displayed decreased catalase activity accompanied by a non-significant increase in malondialdehyde levels. Additionally, there was a significant decrease in the percentage of progressively motile spermatozoa (p < 0.05) in diabetic animals. This study has shed some light on the interplay between DM, AGE, RAGE and mitogen-activated protein kinase signalling in the testes of diabetic rats, which can result in altered sperm function and contribute to male infertility. However, more studies are needed to better understand this complicated process.

Parathyroid hormone ameliorates osteogenesis of human bone marrow mesenchymal stem cells against glucolipotoxicity through p38 MAPK signaling

Diabetes mellitus (DM)-induced glucolipotoxicity is a factor strongly contributing to alveolar bone deficiency. Parathyroid hormone (PTH) has been identified as a main systemic mediator to balance physiological calcium in bone. This study aimed to uncover PTH's potential role in ameliorating the osteogenic capacity of human bone marrow mesenchymal stem cells (HBMSCs) against glucolipotoxicity. Optimal PTH concentrations and high glucose and palmitic acid (GP) were administered to cells, followed by alkaline phosphatase (ALP) staining and ALP activity assay. Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) and Immunoblot were carried out for assessing mRNA and protein amounts, respectively. Cell counting kit-8 (CCK-8) and flow cytometry were performed for quantitating cell proliferation. Osteogenesis and oxidative stress were determined, and the involvement of mitogen-activated protein kinase (MAPK) signaling was further verified. About 1-50 mmol/ml GP significantly inhibited the osteogenic differentiation of HBMSCs. 10^-9 mol/L PTH was found to be the optimal concentration for HBMSC induction. PTH had no effects on HBMSC proliferation, with or without GP treatment. PTH reversed inadequate osteogenesis and excessive oxidative stress in GP-treated HBMSCs. Mechanistically, PTH activated p38 MAPK signaling, while inhibiting p38 MAPK-suppressed PTH's beneficial impacts on HBMSCs. Collectively, PTH promotes osteogenic differentiation in HBMSCs against glucolipotoxicity via p38 MAPK signaling.

The effect of low intensity pulsed ultrasound on dentoalveolar structures during orthodontic force application in diabetic ex-vivo model

OBJECTIVE

This study aimed to investigate the effect of the low intensity pulsed ultrasound (LIPUS) on the dentoalveolar structures during orthodontic force application in ex-vivo model using mandible slice organ culture (MSOC) of diabetic rats.

DESIGN

18 male Wistar rats with a mean weight (275 g) were randomly divided into three main groups: 1) normal rats, 2) Insulin treated diabetic rats, and 3) diabetic rats. Diabetes mellitus (DM) was induced by streptozotocin. Four weeks later, rats were euthanized, mandibles were dissected, divided into 1.5-mm slices creating mandible slice organ cultures (MSOCs). MSOCs were cultured at 37 °C in air with 5 % CO₂. The following day, orthodontic spring delivering a 50-g of force was applied to each slice. In each group, rats were randomly assigned to 2 subgroups; one received 10 min of LIPUS daily and the other was the control. Culture continued for 7 days, and then the sections were prepared for histological and histomorphometric analysis.

RESULTS

For all study groups (Normal, Insulin Treated Diabetic and Diabetic), LIPUS treatment significantly increased the thickness of predentin, cementum, and improved bone remodeling on the tension side and increased odontoblast, sub-odontoblast, and periodontal ligaments cell counts and bone resorption lacunae number on the compression side.

CONCLUSIONS

Application of LIPUS treatment for 10 min daily for a week enhanced bone remodeling and repair of cementum and dentin in normal as well as diabetic MSOCs.

The Relationship Between Polycystic Ovarian Syndrome, Periodontal Disease, and Osteoporosis

Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder to affect women in their reproductive years. There has been growing concern that women with PCOS may suffer from long-term metabolic consequences due to the high degree of insulin resistance that is often present in PCOS. However, few longitudinal studies exist in this area and there is a paucity of data on whether women with PCOS are at risk of other chronic diseases as they age. Specifically, current evidence suggests that reproductive-age women with PCOS may be at increased risk for both osteoporosis and periodontal disease (PD)-both these chronic diseases can have serious implications for health and quality of life. However, few studies have addressed how risk factors for osteoporosis and PD may be altered by aging in PCOS. The PCOS phenotype of women beyond reproductive years is poorly understood, and it is not known whether the metabolic profile of older women with PCOS results in an increased risk of osteoporosis and PD. The objective of this review is to discuss the relationships between PCOS, osteoporosis, and PD, and how these relationships could be impacted during aging. The long-term goal of this review is to provide direction for future research that is needed to more clearly elucidate these relationships and eventually provide a basis for evidence-based health recommendations.

Lowered Expression of MicroRNAs 221 and 222 Mediate Apoptosis Induced by High Glucose in Human Periodontal Ligament Cells

Impaired periodontal healing is a common complication of diabetes mellitus (DM), frequently related to hyperglycemia. MicroRNAs 221 and 222 have been studied as biomarkers for inflammatory diseases, including diabetes, but their role in the periodontal ligament (PL) is unknown. The effects of high glucose on human PL cells death were studied, as well as the expression of microRNA-221 and microRNA-222, potentially modulated by DM. Cells were obtained from the premolar teeth of young humans and cultured for 7 days under different glucose concentrations (5 or 30 mM). MicroRNAs-221/222 expressions were evaluated by real-time RT-PCR and apoptosis by TUNEL assays. Caspase-3 expression was studied by western blotting and immunocytochemistry. High glucose increased apoptosis and caspase-3 protein expression by about 3×. MicroRNA-221 and microRNA-222 expressions decreased by nearly 40% under high glucose. MicroRNA-221 and microRNA-222 inhibition using antagomiRs increased apoptosis by 2-3×, while the expression of caspase-3, a validated target for these microRNAs, was increased by 50%. The overexpression of both microRNAs using miR mimics in high glucose cells did no effect on apoptosis but increased caspase-3 expression by 30%. In conclusion, high glucose induces apoptosis of human PL cells potentially through a reduction of microRNA-221 and microRNA-222 expression and elevation of caspase-3.

Impact of diabetes mellitus simulations on bone cell behavior through in vitro models

Diabetes mellitus (DM) is related to impaired bone healing and an increased risk of bone fractures. While it is recognized that osteogenic differentiation and the function of osteoblasts are suppressed in DM, the influence of DM on osteoclasts is still unclear. Hyperglycemia and inflammatory environment are the hallmark of DM that causes dysregulation of various pro-inflammatory cytokines and alternated gene expression in periodontal ligament cells, osteoblasts, osteocytes, osteoclasts, and osteoclast precursors. A methodological review on conceptual and practical implications of in vitro study models is used for DM simulation on bone cells. Several major databases were screened to find literature related to the study objective. Published literature within last 20 years that used in vitro DM-simulated models to study how DM affects the cellular behavior of bone cells were selected for this review. Studies utilizing high glucose and serum acquired from diabetic animals are the mainly used methods to simulate the diabetic condition. The combination with various simulating factors such as lipopolysaccharide (LPS), hydrogen peroxide (H₂O₂), and advanced glycation end products (AGEs) have been reported in diabetic situations in vitro, as well. Through screening procedure, it was evident DM-simulated conditions exerted negative impact on bone-related cells. However, inconsistent results were found among different reported studies, which could be due to variation in culture conditions, concentrations of the stimulating factors and cell lineage, etc. This manuscript has concisely reviewed currently existing DM-simulated in vitro models and provides valuable insights of detailed components in simulating DM conditions in vitro. Studies using DM-simulated microenvironment revealed that in vitro simulation negatively impacted periodontal ligament cells, osteoblasts, osteocytes, osteoclasts, and osteoclast precursors. Contrarily, studies also indicated beneficial influence on bone-related cells when such conditions are reversed.

Early effect of laser irradiation in signaling pathways of diabetic rat submandibular salivary glands

Low-power laser irradiation (LPLI) is clinically used to modulate inflammation, proliferation and apoptosis. However, its molecular mechanisms are still not fully understood. This study aimed to describe the effects of LPLI upon inflammatory, apoptotic and proliferation markers in submandibular salivary glands (SMGs) in an experimental model of chronic disorder, 24h after one time irradiation. Diabetes was induced in rats by the injection of streptozotocin. After 29 days, these animals were treated with LPLI in the SMG area, and euthanized 24h after this irradiation. Treatment with LPLI significantly decreased diabetes-induced high mobility group box 1 (HMGB1) and tumor necrosis factor alpha (TNF-α) expression, while enhancing the activation of the transcriptional factor cAMP response element binding (CREB) protein. LPLI also reduced the expression of bax, a mitochondrial apoptotic marker, favoring the cell survival. These findings suggest that LPLI can hamper the state of chronic inflammation and favor homeostasis in diabetic rats SMGs.

The impact of diabetes on periodontal diseases

The susceptibility and severity of periodontal diseases is made more severe by diabetes, with the impact on the disease process inversely proportional to the level of glycemic control. Although type 1 diabetes mellitus and type 2 diabetes mellitus have different etiologies, and their impact on bone is not identical, they share many of the same complications. Studies in animals and humans agree that both forms of diabetes increase inflammatory events in periodontal tissue, impair new bone formation, and increase expression of RANKL in response to bacterial challenge. High levels of glucose, reactive oxygen species, and advanced glycation end-products are found in the periodontium of diabetic individuals and lead to increased activation of nuclear factor-kappa B and expression of inflammatory cytokines such as tumor necrosis factor and interleukin-1. Studies in animals, moreover, suggest that there are multiple cell types in periodontal tissues that are affected by diabetes, including leukocytes, vascular cells, mesenchymal stem cells, periodontal ligament fibroblasts, osteoblasts, and osteocytes. The etiology of periodontal disease involves the host response to bacterial challenge that is affected by diabetes, which increases the expression of RANKL and reduces coupled bone formation. In addition, the inflammatory response also modifies the oral microbiota to render it more pathogenic, as demonstrated by increased inflammation and bone loss in animals where bacteria are transferred from diabetic donors to germ-free hosts compared with transfer from normoglycemic donors. This approach has the advantage of not relying upon limited knowledge of the specific bacterial taxa to determine pathogenicity, and examines the overall impact of the microbiota rather than the presumed pathogenicity of a few bacterial groups. Thus, animal studies have provided new insights into pathogenic mechanisms that identify cause-and-effect relationships that are difficult to perform in human studies.

The Interrelationship Between Diabetes, IL-17 and Bone Loss

PURPOSE OF REVIEW

Diabetes has a detrimental effect on bone, increasing the risk of fracture and formation of osteolytic lesions such as those seen in periodontitis. Several diabetic complications are caused by diabetes-enhanced inflammation. This review examines mechanisms by which IL-17 contributes to diabetes-enhanced periodontitis and other effects of IL-17 on bone.

RECENT FINDINGS

IL-17 upregulates anti-bacterial defenses, yet its expression is also linked to a destructive host response in the periodontium. Periodontal disease is caused by bacteria that stimulate an inflammatory response. Diabetes-enhanced IL-17 increases gingival inflammation, which alters the composition of the oral microbiota to increase its pathogenicity. In addition, IL-17 can induce osteoclastogenesis by upregulation of TNF and RANKL in a number of cell types, and IL-17 has differential effects on osteoblasts and their progenitors. Increased IL-17 production caused by diabetes alters the pathogenicity of the oral microbiota and can promote periodontal bone resorption.

Proteomic analysis of human periodontal ligament cells under hypoxia

Background

The periodontal ligament is essential for homeostasis of periodontal tissue. A hypoxic milieu of the periodontal tissue is generated under periodontitis or during orthodontic treatment, which affects the periodontal and bone remodelling process. Here, we provide a comprehensive proteomic characterization of periodontal ligament cells under hypoxic conditions, aiming to reveal previously unappreciated biological changes and to help advance hypoxia-based therapeutic strategies for periodontal diseases.

Methods

Human periodontal ligament cells (hPDLCs) were characterized using immunohistochemistry (IHC) and flow cytometry (FACS). Successful hypoxia treatment of hPDLCs with 1% O₂ was confirmed by qRT-PCR. Proliferation was evaluated using an MTT assay. The proteomic expression profile under hypoxia was studied with the isobaric tags for relative and absolute quantification (iTRAQ) approach followed by protein identification and bioinformatic analysis, and western blot verification was performed.

Results

The hPDLCs were positive for vimentin, CD73 and CD105 and negative for keratin, CD34 and CD45. After hypoxia treatment, the mRNA expression of hypoxia-inducible factor 1a (HIF1a) was upregulated. The proliferation rate was elevated during the first 6 h but decreased from 6 h to 72 h. A total of 220 differentially expressed proteins were quantified in hPDLCs under hypoxia (1% O₂, 24 h), including 153 upregulated and 67 downregulated proteins, five of which were verified by western blot analysis. The Gene Ontology enriched terms included the energy metabolic process, membrane-bound organelle and vesicle, and protein binding terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated several involved pathways, including glycolysis/gluconeogenesis, biosynthesis of amino acids, the HIF-1 signalling pathway, and focal adhesion. A protein–protein interaction (PPI) network demonstrated the dominant role of autophagy over apoptosis under hypoxia.

Conclusion

The proteomic profile of hPDLCs under hypoxia was mainly related to energy metabolism, autophagy, and responses to stimuli such as adhesion and inflammation. Previously unrecognized proteins including solute carrier family proteins, heat shock proteins, ubiquitination-related enzymes, collagen and S100 family proteins are involved in adaptive response to hypoxia in hPDLCs and are thus of great research interest in future work.

Electronic supplementary material

The online version of this article (10.1186/s12953-019-0151-2) contains supplementary material, which is available to authorized users.

The link between advanced glycation end products and apoptosis in delayed wound healing

Advanced glycation end products (AGEs) are naturally occurring molecules that start to accumulate from embryonic developmental stages and form as part of normal ageing. When reducing sugars interact with and modify proteins or lipids, AGE production occurs. AGE formation accelerates in chronic hyperglycemic conditions, and high AGE levels have been associated with the pathogenesis of various diseases. In addition, enhanced levels of AGEs have been linked to delayed wound healing as seen in patients with diabetes mellitus. Research has provided numerous ways in which a high AGE concentration results in impaired wound healing, including oxidative stress, structural and functional changes to proteins important in wound repair, an enhanced inflammatory response by activation of transcription factors, and possible exaggerated apoptosis of cells necessary to the wound repair process. Apoptosis is a naturally occurring cell death process that is significant for normal tissue functioning and plays an important role in wound repair by preventing a prolonged inflammatory response and excessive scar formation. Abnormal apoptosis affects wound healing, resulting in slow healing wounds. This review will summarize the role of AGEs in wound healing, focusing on the mechanisms by which AGEs lead to apoptosis in various cell types. The review provides the way forward for medical research and molecular studies as it focuses on the mechanisms by which AGEs induce apoptosis in various cell types, including fibroblasts, osteoblasts, neuronal cells, and endothelial cells. Reviewing the mechanisms of AGE-linked apoptosis is important in understanding the impact of high AGE levels in delayed wound healing in diabetic patients due to abnormal apoptosis of cells necessary to the wound healing process.

The effect of NLRP inflammasome on the regulation of AGEs-induced inflammatory response in human periodontal ligament cells

BACKGROUND AND OBJECTIVE

Diabetes influences the frequency and development of periodontitis. Inflammation of human periodontal ligament cells (HPDLCs) participates in this pathologic process. Hence, this study aims to explore whether advanced glycation end products (AGEs), by-products of diabetes, could exaggerate inflammation induced by muramyl dipeptide (MDP) in HPDLCs, and whether nucleotide-binding oligomerization domain-like receptors (NLRs) signaling pathway was involved.

MATERIAL AND METHODS

Human periodontal ligament cells were pre-treated with 100 μg/mL AGEs for 24 hours and stimulated with 10 μg/mL MDP for 24 hours. IL-6, IL-1β, and RAGE were detected, and the activation of NF-κB signaling pathway was observed. The expression of NLRs was evaluated with or without silencing RAGE or blocking NF-κB pathway under AGEs stimulation. Statistical analyses were performed by using independent sample t test.

RESULTS

Advanced glycation end products induced significant increase of inflammatory cytokines in HPDLCs (P < 0.05). Results of western blot (WB) showed that after 45 minutes stimulation of AGEs, p-p65/p65 ratio peaked; AGEs promoted the expression of NLRP1, NLRP3, and apoptosis-associated speck-like protein containing a CARD (ASC). After silencing RAGE or blocking NF-κB pathway, the up-regulation of NLRs protein caused by AGEs was attenuated. Additionally, AGEs pre-treatment could enhance the inflammatory response of MDP and the expression of NLRs, which were demonstrated by more expression of IL-6, IL-1β, NOD2, NLRP1, NLRP3, and ASC.

CONCLUSION

Advanced glycation end products induced inflammatory response in HPDLCs via NLRP1-inflammasome and NLRP3-inflammasome activation in which NF-κB signal pathway was involved. Besides, AGEs promoted the inflammatory response of MDP via NOD2, NLRP1-inflammasome, and NLRP3-inflammasome.

RAGE-dependent mitochondria pathway: a novel target of silibinin against apoptosis of osteoblastic cells induced by advanced glycation end products

Advanced glycation end products (AGEs) can stimulate osteoblast apoptosis and have a critical role in the pathophysiology of diabetic osteoporosis. Mitochondrial abnormalities are closely related to osteoblast dysfunction. However, it remains unclear whether mitochondrial abnormalities are involved in AGE-induced osteoblastic cell apoptosis. Silibinin, a major flavonolignan compound of silimarin, has strong antioxidant and mitochondria-protective properties. In the present study, we explored the possible mitochondrial mechanisms underlying AGE-induced apoptosis of osteoblastic cells and the effect of silibinin on osteoblastic cell apoptosis. We demonstrated that mitochondrial abnormalities largely contributed to AGE-induced apoptosis of osteoblastic cells, as evidenced by enhanced mitochondrial oxidative stress, conspicuous reduction in mitochondrial membrane potential and adenosine triphosphate production, abnormal mitochondrial morphology, and altered mitochondrial dynamics. These AGE-induced mitochondrial abnormalities were mainly mediated by the receptor of AGEs (RAGE). In addition, we found that silibinin directly downregulated the expression of RAGE and modulated RAGE-mediated mitochondrial pathways, thereby preventing AGE-induced apoptosis of osteoblastic cells. This study not only provides a new insight into the mitochondrial mechanisms underlying AGE-induced osteoblastic cell apoptosis, but also lays a foundation for the clinical use of silibinin for the prevention or treatment of diabetic osteoporosis.

GSK126 (EZH2 inhibitor) interferes with ultraviolet A radiation-induced photoaging of human skin fibroblast cells

Polycomb group genes (PcG) encode chromatin modification proteins that are involved in the epigenetic regulation of cell differentiation, proliferation and the aging processes. The key subunit of the PcG complex, enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2), has a central role in a variety of mechanisms, such as the formation of chromatin structure, gene expression regulation and DNA damage. In the present study, ultraviolet A (UVA) was used to radiate human dermal fibroblasts in order to construct a photo-aged cell model. Subsequently, the cell viability assay, Hoechst staining, apoptosis detection using flow cytometry, senescence-associated β-galactosidase (SA-β-gal) staining and erythrocyte exclusion experiments were performed. GSK126, a histone methylation enzyme inhibitor of EZH2, was used as an experimental factor. Results suggested that GSK126 downregulated the mRNA expression levels of EZH2 and upregulated the mRNA expression levels of BMI-1. Notably, GSK126 affected the transcription of various photoaging-related genes and thus protected against photoaging induced by UVA radiation.

Peri-implant conditions and levels of advanced glycation end products among patients with different glycemic control

BACKGROUND

A close relationship between poor glycemic control and peri-implant break down has been demonstrated. It is hypothesized that levels of advanced glycation end products (AGEs) in peri-implant sulcular fluid (PISF) are higher with increased glycemic levels in type 2 diabetes mellitus patients.

PURPOSE

In the present study, we examined the clinical and radiographic peri-implant parameters and levels of AGEs among different glycemic levels in diabetic patients and assessed whether the levels of AGEs correlate with clinical peri-implant parameters.

MATERIALS AND METHODS

Ninety-three patients who participated in this study were divided into four groups; Group-1: HbA1c 6.1%-8%; Group-2: HbA1c 8.1%-10%; Group-3: HbA1c > 10%; Group-4: non-diabetic individuals with HbA1c < 6%. Peri-implant plaque index (PI), bleeding on probing (BOP), probing depth (PD) and crestal bone loss (CBL) were recorded. Levels of AGEs in PISF were quantified using enzyme-linked immunosorbent assay. Between-group comparison of means was verified with Kruskal-Wallis test and Pearson correlation coefficient for correlations of AGE levels with peri-implant parameters.

RESULTS

Peri-implant PI, BOP, PD, and CBL were significantly higher in group-1, -2, and -3 as compared to non-diabetic patients (P < .05). These parameters were significantly higher in group-2 and group-3 versus group-1 (P < .01). Mean PI, BOP, PD, and CBL were comparable between group-2 and group-3 patients (P > .05). Mean levels of AGEs in PISF were significantly higher in relation to higher levels of HbA1c levels. Significant positive correlations were found between AGEs and PD (P = .0221) and CBL (P = .0425); and significant negative correlation was found for PI (P = .0376) in patients with HbA1c levels >10%, respectively.

CONCLUSIONS

Clinical and radiographic peri-implant parameters were poor and levels of AGEs were significantly high in patients with high glycemic levels. These findings suggest that AGEs may be considered as potential marker of inflammation in diabetic individuals with peri-implantitis.

Inhibition of the receptor for advanced glycation promotes proliferation and repair of human periodontal ligament fibroblasts in response to high glucose via the NF-κB signaling pathway

OBJECTIVE

To observe if inhibition of the receptor for advanced glycation endproducts (RAGE) promotes proliferation and repair of human periodontal ligament fibroblasts (hPDLFs) stimulated by high glucose. In addition, we also discuss the effects of the NF-κB signaling pathway in relation to this process.

METHODS

Primary cultured hPDLFs were exposed to either low glucose (5.5 mmol/L) or high glucose (25 mmol/L), and RAGE expression was measured by Western blot analysis. Cells were cultured in high glucose with different concentrations of the RAGE inhibitor, FPS-ZM1. We measured cell proliferation using the Cell Counting Kit-8 and expression of collagen type 1 and fibronectin by real-time PCR and ELISA, respectively. The relative protein expression levels of NF-κB p65 and phosphorylated p65 were measured by Western blot analysis.

RESULTS

High glucose enhanced RAGE expression and suppressed cell growth. While FPS-ZM1 increased proliferation and expression of repair-related factors in high glucose, there was a concurrent decline in the phosphorylation level of NF-κB p65.

CONCLUSION

FPS-ZM1 rescued the proliferative capacity and repair capability of hPDLFs via the RAGE-NF-κB signaling pathway in response to high glucose.

Generation of Advanced Glycation End-Products (AGEs) by glycoxidation mediated by copper and ROS in a human serum albumin (HSA) model peptide: reaction mechanism and damage in motor neuron cells

Glucose, in the presence of reactive oxygen species (ROS), acts as an as an oxidative agent and drives deleterious processes in Diabetes Mellitus. We have studied the mechanism and the toxicological effects of glucose-dependent glycoxidation reactions driven by copper and ROS, using a model peptide based on the exposed sequence of Human Serum Albumin (HSA) and containing a lysine residue susceptible to copper complexation. The main products of these reactions are Advanced Glycation End-products (AGEs). Carboxymethyl lysine and pyrraline condensed on the model peptide, generating a Modified Peptide (MP). These products were isolated, purified, and tested on cultured motor neuron cells. We observed DNA damage, enhancement of membrane roughness, and formation of domes. We evaluated nuclear abnormalities by the cytokinesis-blocked micronucleus assay and we measured cytostatic and cytotoxic effects, chromosomal breakage, nuclear abnormalities, and cell death. AGEs formed by glycoxidation caused large micronucleus aberrations, apoptosis, and large-scale nuclear abnormalities, even at low concentrations.

Effects of fluoride on proliferation and mineralization in periodontal ligament cells in vitro

Fluoride, which is often added to toothpaste or mouthwash in order to protect teeth from decay, may be a novel therapeutic approach for acceleration of periodontal regeneration. Therefore, we investigated the effects of fluoride on proliferation and mineralization in human periodontal ligament cells in vitro. The periodontal ligament cells were stimulated with various concentrations of NaF added into osteogenic inductive medium. Immunohistochemistry of cell identification, cell proliferation, alkaline phosphatase (ALP) activity assay, Alizarin red S staining and quantitative real-time-polymerase chain reaction (RT-PCR) were performed. Moderate concentrations of NaF (50-500 μmol/L) had pro-proliferation effects, while 500 μmol/L had the best effects. ALP activity and calcium content were significantly enhanced by 10 μmol/L NaF with osteogenic inductive medium. Quantitative RT-PCR data varied in genes as a result of different NaF concentrations and treatment periods. We conclude that moderate concentrations of NaF can stimulate proliferation and mineralization in periodontal ligament cells. These in vitro findings may provide a novel therapeutic approach for acceleration of periodontal regeneration by addition of suitable concentrations of NaF into the medication for periodontitis treatment, i.e., into periodontal packs and tissue patches.

Efficacy of scaling and root planning with and without adjunct Nd:YAG laser therapy on clinical periodontal parameters and gingival crevicular fluid interleukin 1-beta and tumor necrosis factor-alpha levels among patients with periodontal disease: A prospective randomized split-mouth clinical study

BACKGROUND AND AIM

Limited evidence exists regarding the role of scaling and root planning (SRP) with adjunct neodymium yttrium aluminum garnet (Nd:YAG) laser therapy in reducing periodontal parameters (plaque index [PI], bleeding on probing [BOP] and probing pocket depth [PPD]) and levels of proinflammatory cytokines in the gingival crevicular fluid (GCF) among patients with periodontal disease (PD). The aim was to assess the effect of SRP with and without adjunct Nd:YAG laser therapy on clinical periodontal parameters and GCF interleukin 1-beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) levels among patients with PD.

METHODS

Demographic data was collected using a questionnaire. Mandibular right and left quadrants were randomly divided into test- (SRP+Nd:YAG laser) and control-sites (SRP alone). PI, BOP and PPD were assessed and GCF IL-1β and TNF-α levels were measured at baseline and at 3- and 6-month follow-up. Level of significance was set at P<0.05.

RESULTS

Twenty-eight male patients with PD were included. At 3- and 6-month follow-up, PI (P<0.01), BOP (P<0.01) and PPD (P<0.01) were significantly higher in the control-sites than test-sites. In the test-sites, PI, BOP and PPD and GCF IL-1β and TNF-α levels were comparable at 3- and 6-month follow-up. At 6-month follow-up, IL-1β (P<0.05) and TNF-α (P<0.05) levels were significantly higher in control-sites than test-sites at 3- and 6-month follow-up.

CONCLUSION

At 3- and 6-month follow-up, SRP+Nd:YAG therapy was more effective in reducing periodontal inflammatory parameters and GCF IL-1β and TNF-α levels compared with SRP alone.

Detection of RAGE expression and its application to diabetic wound age estimation

With the prevalence of diabetes, it is becoming important to analyze the diabetic wound age in forensic practice. The present study investigated the time-dependent expression of receptor for advanced glycation end products (RAGE) during diabetic wound healing in mice and its applicability to wound age determination by immunohistochemistry, double immunofluorescence, and Western blotting. After an incision was created in genetically diabetic db/db mice and control mice, mice were killed at posttraumatic intervals ranging from 6 h to 14 days, followed by the sampling of wound margin. Compared with control mice, diabetic mice showed the delayed wound healing. In control and diabetic wound specimens, RAGE immunoreactivity was observed in a small number of polymorphonuclear cells (PMNs), a number of macrophages, and fibroblasts. Morphometrically, the positive ratios of RAGE in macrophages or fibroblasts considerably increased in diabetic wounds during late repair, which exceeded 60% at 7 and 10 days post-injury. There were no control wound specimens to show a ratio of >60% in macrophages or fibroblasts. By Western blotting analysis, the ratios of RAGE to GAPDH were >1.4 in all diabetic wound samples from 7 to 10 days post-injury, which were >1.8 at 10 days after injury. By comparison, no control wound specimens indicated a ratio of >1.4. In conclusion, the expression of RAGE is upregulated and temporally distributed in macrophages and fibroblasts during diabetic wound healing, which might be closely involved in prolonged inflammation and deficient healing. Moreover, RAGE is promising as a useful marker for diabetic wound age determination.

Advanced glycosylation end product promotes forkhead box O1 and inhibits Wnt pathway to suppress capacities of epidermal stem cells

Diabetes mellitus is frequently accompanied by chronic complications like delayed wound healing, which is consider to be attributed to the accumulation of advanced glycosylation end product (AGE). However, the impacts of AGE on epidermal stem cells (ESCs) are largely unknown. This study aims to address the influence and mechanism of AGE on ESCs. ESCs isolated from rats were cultured in AGE-modified bovine serum albumin and transfected with small interfering RNA to knock down AGE-specific receptor (AGER). Expression of stem cell markers integrin β1 (ITGB1) and keratin 19 (KRT19), cell viability, apoptosis and reactive oxygen species (ROS) were examined. Wnt pathway-related factors Wnt family member 1 (WNT1), WNT3A, β-catenin, v-myc avian myelocytomatosis viral oncogene homolog (MYC), cyclin D1 (CCND1) and matrix metallopeptidase 7 (MMP7) were quantified. The interaction between forkhead box O1 (FOXO1) and β-catenin was assessed by co-immunoprecipitation. Results indicated that AGE down-regulated ITGB1 and KRT19 expression, suppressed ESC viability and promoted apoptosis, and ROS level (P < 0.01), implying decreased capacities of ESCs. AGE also promoted AGER and FOXO1, while AGER knockdown had the opposite effects. Moreover, AGER knockdown elevated the level of WNT1, WNT3A, MYC, CCND1 and MMP7 that were suppressed by AGE (P < 0.01). Immunoprecipitation analysis showed that FOXO1 could compete with lymphoid enhancer binding factor 1 to interact with β-catenin, which might help to elucidate the mechanism of AGE repressing ESCs. This study helps to understand the mechanism of accumulated AGE in affecting ESC capacities, and provides potential therapeutic targets to meliorate diabetic wound healing.

iRAGE as a novel carboxymethylated peptide that prevents advanced glycation end product-induced apoptosis and endoplasmic reticulum stress in vascular smooth muscle cells

Advanced glycation end-products (AGE) and the receptor for AGE (RAGE) have been linked to numerous diabetic vascular complications. RAGE activation promotes a self-sustaining state of chronic inflammation and has been shown to induce apoptosis in various cell types. Although previous studies in vascular smooth muscle cells (VSMC) showed that RAGE activation increases vascular calcification and interferes with their contractile phenotype, little is known on the potential of RAGE to induce apoptosis in VSMC. Using a combination of apoptotic assays, we showed that RAGE stimulation with its ligand CML-HSA promotes apoptosis of VSMC. The formation of stress granules and the increase in the level of the associated protein HuR point toward RAGE-dependent endoplasmic reticulum (ER) stress, which is proposed as a key contributor of RAGE-induced apoptosis in VSMC as it has been shown to promote cell death via numerous mechanisms, including up-regulation of caspase-9. Chronic NF-κB activation and modulation of Bcl-2 homologs are also suspected to contribute to RAGE-dependent apoptosis in VSMC. With the goal of reducing RAGE signaling and its detrimental impact on VSMC, we designed a RAGE antagonist (iRAGE) derived from the primary amino acid sequence of HSA. The resulting CML peptide was selected for the high glycation frequency of the primary sequence in the native protein in vivo. Pretreatment with iRAGE blocked 69.6% of the increase in NF-κB signaling caused by RAGE activation with CML-HSA after 48h. Preincubation with iRAGE was successful in reducing RAGE-induced apoptosis, as seen through enhanced cell survival by SPR and reduced PARP cleavage. Activation of executioner caspases was 63.5% lower in cells treated with iRAGE before stimulation with CML-HSA. To our knowledge, iRAGE is the first antagonist shown to block AGE-RAGE interaction and we propose the molecule as an initial candidate for drug discovery.

Periodontal Status and Whole Salivary Cytokine Profile Among Smokers and Never-Smokers With and Without Prediabetes

BACKGROUND

Whole salivary interleukin (IL)-1β and IL-6 in smokers and never-smokers with prediabetes remains uninvestigated. The aim of this study is to assess the periodontal status and whole salivary IL-1β and IL-6 levels among smokers and never-smokers with and without prediabetes (controls).

METHODS

Ninety-five males (45 with prediabetes and 50 systemically healthy controls) were included. Twenty-seven controls and 29 patients with prediabetes were smokers. Periodontal parameters (plaque index, bleeding on probing, probing depth, clinical attachment loss, and marginal bone loss) were measured, and the number of missing teeth were recorded. Fasting blood glucose (FBG) and hemoglobin A1c (HbA1c) levels were recorded. Unstimulated whole saliva samples were collected, unstimulated whole salivary flow rate (UWSFR) was determined, and IL-1β and IL-6 levels were measured. P values <0.05 were considered statistically significant.

RESULTS

FBG (P <0.05) and HbA1c (P <0.05) levels were higher among patients with prediabetes than controls. All patients with prediabetes were hyperglycemic. UWSFR was significantly higher among controls than among patients with prediabetes (P <0.05). Periodontal parameters and whole salivary IL-1β and IL-6 levels were comparable among smokers and never-smokers with prediabetes. Among controls, periodontal parameters and whole salivary IL-1β and IL-6 levels were higher among smokers than never-smokers (P <0.05).

CONCLUSIONS

Among controls, periodontal inflammation was worse, and whole salivary IL-1β and IL-6 levels are higher in smokers than never-smokers. Among patients with prediabetes, periodontal inflammation and whole salivary IL-1β and IL-6 levels were comparable between smokers and never-smokers.