Altered fibroblast proliferation and apoptosis in diabetic gingival wounds

The bidirectional association between diabetes and periodontitis, from basic to clinical

The prevalence and severity of periodontitis are increased and advanced in diabetes. Severe periodontitis elicits adverse effects on diabetes by impairing insulin actions due to systemic microinflammation. Recent studies unveil the emerging findings and molecular basis of the bidirectional relationship between periodontitis and diabetes. In addition to conventional mechanisms such as hyperglycemia, hyperlipidemia, and chronic inflammation, deficient insulin action may play a pathogenic role in the progression of periodontitis under diabetes. Epidemiologically, from the viewpoint of the adverse effect of periodontitis on diabetes, recent studies have suggested that Asians including Japanese and Asian Americans with diabetes and mild obesity (BMI <25 kg/m2) should pay more attention to their increased risk for cardiovascular diseases. In this review, we summarize recent findings on the effect of diabetes on periodontitis from the viewpoint of abnormalities in metabolism and insulin resistance with novel mechanisms, and the influence of periodontitis on diabetes mainly focused on micro-inflammation related to mature adipose tissue and discuss future perspectives about novel approaches to interrupt the adverse interrelationship.

Combined therapeutic strategy based on blocking the deleterious effects of AGEs for accelerating diabetic wound healing

Diabetic foot ulcer is a serious complication of diabetes. Excessive accumulation of advanced glycation end products (AGEs) is one of the critical pathogenic factors in postponing diabetic wound healing. The main pathogenic mechanisms of AGEs include inducing cellular dysfunction, prolonging inflammatory response, increasing oxidative stress and reducing endogenous nitric oxide (NO) production. Combination therapy of blocking the deleterious effects of AGEs and supplementing exogenous NO is hypothesized to promote diabetic wound healing. Here, we presented nanoparticles/hydrogel composite dressings to co-delivery rosiglitazone and S-nitroso glutathione into the wound bed. The designed co-delivery system augmented the survival of fibroblasts, reduced oxidative stress levels, reversed the change of mitochondrial membrane potential and decreased the proinflammatory cytokine expression. Local sustained release of therapeutic agents significantly improved the wound healing of diabetic rats including increasing the wound closure rate, alleviating inflammation, promoting collagen fiber production and angiogenesis. Our finding indicated this local deliver strategy aimed at inhibiting the toxic effects of AGEs has great clinical potential for diabetic wound treatment.

Lipotoxicity: The missing link between diabetes and periodontitis?

Lipotoxicity refers to the accumulation of lipids in tissues other than adipose tissue (body fat). It is one of the major pathophysiological mechanisms responsible for the progression of diabetes complications such as non-alcoholic fatty liver disease and diabetic nephropathy. Accumulating evidence indicates that lipotoxicity also contributes significantly to the toxic effects of diabetes on periodontitis. Therefore, we reviewed the current in vivo, in vitro, and clinical evidence of the detrimental effects of lipotoxicity on periodontitis, focusing on its molecular mechanisms, especially oxidative and endoplasmic reticulum stress, inflammation, ceramides, adipokines, and programmed cell death pathways. By elucidating potential therapeutic strategies targeting lipotoxicity and describing their associated mechanisms and clinical outcomes, including metformin, statins, liraglutide, adiponectin, and omega-3 PUFA, this review seeks to provide a more comprehensive and effective treatment framework against diabetes-associated periodontitis. Furthermore, the challenges and future research directions are proposed, aiming to contribute to a more profound understanding of the impact of lipotoxicity on periodontitis.

Mesoporous MOFs with ROS scavenging capacity for the alleviation of inflammation through inhibiting stimulator of interferon genes to promote diabetic wound healing

Excessive production of reactive oxygen species (ROS) and inflammation are the key problems that impede diabetic wound healing. In particular, dressings with ROS scavenging capacity play a crucial role in the process of chronic wound healing. Herein, Zr-based large-pore mesoporous metal-organic frameworks (mesoMOFs) were successfully developed for the construction of spatially organized cascade bioreactors. Natural superoxide dismutase (SOD) and an artificial enzyme were spatially organized in these hierarchical mesoMOFs, forming a cascade antioxidant defense system, and presenting efficient intracellular and extracellular ROS scavenging performance. In vivo experiments demonstrated that the SOD@HMUiO-MnTCPP nanoparticles (S@M@H NPs) significantly accelerated diabetic wound healing. Transcriptomic and western blot results further indicated that the nanocomposite could inhibit fibroblast senescence and ferroptosis as well as the stimulator of interferon genes (STING) signaling pathway activation in macrophages mediated by mitochondrial oxidative stress through ROS elimination. Thus, the biomimetic multi-enzyme cascade catalytic system with spatial ordering demonstrated a high potential for diabetic wound healing, where senescence, ferroptosis, and STING signaling pathways may be potential targets.

The impact of metabolic disorders on management of periodontal health in children

Periodontitis is a chronic inflammatory disease caused by plaque biofilm which shares risk factors with systemic chronic diseases such as diabetes, cardiovascular disease, and osteoporosis. Many studies have found increased prevalence and rate of progression of periodontal disease in children with common metabolic disorders. Although the causal relationship and specific mechanism between them has not been determined yet. The aim of this paper is to progress on the impact of metabolic disorders on periodontal health in children and the underlying mechanisms, which provides new evidences for the prevention and intervention of metabolic disorders and periodontitis in children.

Topical metformin accelerates wound healing by promoting collagen synthesis and inhibiting apoptosis in a diabetic wound model

The wound healing process, which is a pathophysiological process that includes various phases, is interrupted in diabetes due to hyperglycemia, and since deterioration occurs in these phases, a normal healing process is not observed. The aim of the current study is to investigate the proliferative and antiapoptotic effects of metformin on wound healing after topical application on diabetic and non-diabetic wounds. For this purpose, we applied metformin topically on the full-thickness excisional wound model we created in diabetic and nondiabetic groups. We investigated the effects of metformin on the apoptotic index by the Terminal deoxynucleotidyl transferase mediated dUTP Nick-End Labeling method and on collagen-I, collagen-III, p53, and c-jun expression levels by quantitative reverse transcription polymerase chain reaction technique in wound biopsy tissues. Our results showed that c-jun and p53 mRNA levels and apoptotic index increased with the effect of diabetes, while collagen synthesis was disrupted. As a result of the study, we showed that metformin increases cellular proliferation and has anti-apoptotic effects by increasing collagen-I/III expression and decreasing p53/c-jun level, especially in diabetic wounds and also in normal wounds. In conclusion, the topical effect of metformin on diabetic wounds reversed the adverse effects caused by diabetes, increasing the wound healing rate and improving the wound repair process.

Silencing of topical proline hydroxylase domain 2 promotes the healing of rat diabetic wounds by phosphorylating AMPK

BACKGROUND

For diabetic ulcers, the impaired response to hypoxia is a key feature associated with delayed healing. In the early phase of hypoxia, hypoxic signaling activates the AMPK system through direct phosphorylation of the PHD2 pathway, producing a significant endogenous hypoxic protective effect.

METHODS

Twenty Sprague-Dawley (SD) rats were randomly divided into two groups: treatment (sh-PHD2) and control (sh-Control). Using lentiviral encapsulation of PHD2-shRNA and transfection, the silencing efficiency of PHD2 expression was verified in rat dermal fibroblasts (RDF) and in rat aortic endothelial cells (RAECs). Changes in the ability of RDF and RAECs to proliferate, migrate, and in the rate of ATP production were observed and then tested after inhibition of AMPK phosphorylation using dorsomorphin. The lentiviral preparation was injected directly into the wounds of rats and wound healing was recorded periodically to calculate the healing rate. Wounded tissues were excised after 14 days and the efficiency of PHD2 silencing, as well as the expression of growth factors, was examined using molecular biology methods. Histological examination was performed to assess CD31 expression and therefore determine effects on angiogenesis.

RESULTS

Lentiviral-encapsulated PHD2-sh-RNA effectively suppressed PHD2 expression and improved the proliferation, migration, and ATP production rate of RDF and RAEC, which were restored to their previous levels after inhibition of AMPK. The rate of wound healing, vascular growth, and expression of growth factors were significantly improved in diabetic-model rats after local silencing of PHD2 expression.

CONCLUSION

Silencing of PHD2 promoted wound healing in diabetic-model SD rats by activating AMPK phosphorylation.

Reduced Bone Regeneration in Rats With Type 2 Diabetes Mellitus as a Result of Impaired Stromal Cell and Osteoblast Function-A Computer Modeling Study

Bone has the fascinating ability to self-regenerate. However, under certain conditions, such as type 2 diabetes mellitus (T2DM), this ability is impaired. T2DM is a chronic metabolic disease known by the presence of elevated blood glucose levels that is associated with reduced bone regeneration capability, high fracture risk, and eventual non-union risk after a fracture. Several mechanical and biological factors relevant to bone regeneration have been shown to be affected in a diabetic environment. However, whether impaired bone regeneration in T2DM can be explained due to mechanical or biological alterations remains unknown. To elucidate the relevance of either one, the aim of this study was to investigate the relative contribution of T2DM-related alterations on either cellular activity or mechanical stimuli driving bone regeneration. A previously validated in silico computer modeling approach that was capable of explaining bone regeneration in uneventful conditions of healing was further developed to investigate bone regeneration in T2DM. Aspects analyzed included the presence of mesenchymal stromal cells (MSCs), cellular migration, proliferation, differentiation, apoptosis, and cellular mechanosensitivity. To further verify the computer model findings against in vivo data, an experimental setup was replicated, in which regeneration was compared in healthy and diabetic after a rat femur bone osteotomy stabilized with plate fixation. We found that mechanical alterations had little effect on the reduced bone regeneration in T2DM and that alterations in MSC proliferation, MSC migration, and osteoblast differentiation had the highest effect. In silico predictions of regenerated bone in T2DM matched qualitatively and quantitatively those from ex vivo μCT at 12 weeks post-surgery when reduced cellular activities reported in previous in vitro and in vivo studies were included in the model. The presented findings here could have clinical implications in the treatment of bone fractures in patients with T2DM. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Influence of Reactive Oxygen Species on Wound Healing and Tissue Regeneration in Periodontal and Peri-Implant Tissues in Diabetic Patients

Diabetes mellitus (DM) is associated with periodontal disease. Clinically, periodontal treatment is less effective for patients with DM. Oxidative stress is one of the mechanisms that link DM to periodontitis. The production of reactive oxygen species (ROS) is increased in the periodontal tissues of patients with DM and is involved in the development of insulin resistance in periodontal tissues. Insulin resistance decreases Akt activation and inhibits cell proliferation and angiogenesis. This results in the deterioration of wound healing and tissue repair in periodontal tissues. Antioxidants and insulin resistance ameliorants may inhibit ROS production and improve wound healing, which is worsened by DM. This manuscript provides a comprehensive review of the most recent basic and clinical evidence regarding the generation of ROS in periodontal tissues resulting from microbial challenge and DM. This study also delves into the impact of oxidative stress on wound healing in the context of periodontal and dental implant therapies. Furthermore, it discusses the potential benefits of administering antioxidants and anti-insulin resistance medications, which have been shown to counteract ROS production and inflammation. This approach may potentially enhance wound healing, especially in cases exacerbated by hyperglycemic conditions.

Addition of Resolvins D1 or E1 to Collagen Membranes Mitigates Their Resorption in Diabetic Rats

Uncontrolled diabetes is characterized by aberrant inflammatory reactions and increased collagenolysis. We have reported that it accelerates the degradation of implanted collagen membranes (CM), thus compromising their function in regenerative procedures. In recent years, a group of physiological anti-inflammatory agents called specialized pro-resolving lipid mediators (SPMs) have been tested as a treatment for various inflammatory conditions, either systemically or locally, via medical devices. Yet, no study has tested their effect on the fate of the biodegradable material itself. Here, we measured the in vitro release over time of 100 or 800 ng resolvin D1 (RvD1) incorporated into CM discs. In vivo, diabetes was induced in rats with streptozotocin, while buffer-injected (normoglycemic) rats served as controls. Resolvins (100 or 800 ng of RvD1 or RvE1) were added to biotin-labeled CM discs, which were implanted sub-periosteally over the calvaria of rats. Membrane thickness, density, and uniformity were determined by quantitative histology after 3 weeks. In vitro, significant amounts of RvD1 were released over 1-8 days, depending on the amount loaded. In vivo, CMs from diabetic animals were thinner, more porous, and more variable in thickness and density. The addition of RvD1 or RvE1 improved their regularity, increased their density, and reduced their invasion by the host tissue significantly. We conclude that addition of resolvins to biodegradable medical devices can protect them from excessive degradation in systemic conditions characterized by high degree of collagenolysis.

Mechanisms of diabetic foot ulceration: A review

Diabetic foot ulcers (DFUs) are associated with complex pathogenic factors and are considered a serious complication of diabetes. The potential mechanisms underlying DFUs have been increasingly investigated. Previous studies have focused on the three aspects of diabetic peripheral vascular disease, neuropathy, and wound infections. With advances in technology, researchers have been gradually conducting studies using immune cells, endothelial cells, keratinocytes, and fibroblasts, as they are involved in wound healing. It has been reported that the upregulation or downregulation of molecular signaling pathways is essential for the healing of DFUs. With a recent increase in the awareness of epigenetics, its regulatory role in wound healing has become a much sought-after trend in the treatment of DFUs. This review focuses on four aspects involved in the pathogenesis of DFUs: physiological and pathological mechanisms, cellular mechanisms, molecular signaling pathway mechanisms, and epigenetics. Given the challenge in the treatment of DFUs, we are hopeful that our review will provide new ideas for peers.

A novel glycoprotein from earthworm extract PvE-3: Insights of their characteristics for promoting diabetic wound healing and attenuating methylglyoxal-induced cell damage

Diabetic chronic wound is a worldwide medical burden related to overdosed methylglyoxal (MGO) synthesis, which is the major precursor of glycation of proteins and DNA and is related to the dysfunction of dermal cells thus leading to chronic refractory wounds. Previous studies proved that earthworm extract accelerates diabetic wound healing and possesses cell proliferation and antioxidative effects. However, the effects of earthworm extract on MGO-damaged fibroblasts, the inner mechanisms of MGO-induced cell damage and the functional components in earthworm extract are still poorly understood. Firstly, we evaluated the bioactivities of the earthworm extract PvE-3 on the diabetic wound model and the diabetic related cell damage model. Then the mechanisms were investigated through transcriptomics, flow cytometry and fluorescence probe. The results revealed that PvE-3 promoted diabetic wound healing and protected fibroblast function in cell-damaged conditions. Meanwhile, the high-throughput screening implied the inner mechanisms of diabetic wound healing and PvE-3 cytoprotection effect were involved in the muscle cell function, the cell cycle regulation and the mitochondrial transmembrane potential depolarization. The functional glycoprotein isolated from PvE-3 possessed EGF-like domain which had a strong binding affinity with EGFR. The findings provided references to explore the potential treatments of diabetic wound healing.

High Glucose Induces Late Differentiation and Death of Human Oral Keratinocytes

Keratinocytes are essential cells for wound repair. Impaired oral wound healing is common in diabetic patients with periodontal disease. High glucose, or hyperglycemia, impairs the cellular function of different cell types. However, it is unknown whether high glucose has a detrimental effect on the functions of oral keratinocytes. In the current study, a human gingival keratinocyte cell line, telomerase immortalized gingival keratinocytes (TIGK), was treated with high glucose (24 and 48 mM) for up to 120 h. Proliferation, migration, cell viability, and production of markers of differentiation, growth factors and enzymatic antioxidants were assessed after high glucose treatment. The results showed that high glucose significantly inhibited TIGK proliferation and migration. High glucose also induced significant cell death through apoptosis and necrosis as determined by flow cytometry, especially at 120 h after high glucose treatment. Necrosis was the dominant form of cell death induced. Real-time PCR showed that high glucose treatment upregulated mRNA expression of late keratinocyte differentiation makers, such as keratin 1, 10, 13 and loricrin, and downregulated enzymatic antioxidants, including superoxide dismutase 1, catalase, nuclear factor erythroid 2 -related factor 2, heme oxygenase 1. In conclusion, high glucose impairs the proliferation and migration of oral keratinocytes and likely induces cell death through the promotion of late cell differentiation and down-regulation of enzymatic antioxidants.

Diabetes complications and extracellular vesicle therapy

Diabetes is a chronic disorder characterized by dysregulated glycemic conditions. Diabetic complications include microvascular and macrovascular abnormalities and account for high morbidity and mortality rates in patients. Current clinical approaches for diabetic complications are limited to symptomatic treatments and tight control of blood sugar levels. Extracellular vesicles (EVs) released by somatic and stem cells have recently emerged as a new class of potent cell-free therapeutic delivery packets with a great potential to treat diabetic complications. EVs contain a mixture of bioactive molecules and can affect underlying pathological processes in favor of tissue healing. In addition, EVs have low immunogenicity and high storage capacity while maintaining nearly the same regenerative and immunomodulatory effects compared to current cell-based therapies. Therefore, EVs have received increasing attention for diabetes-related complications in recent years. In this review, we provide an outlook on diabetic complications and summarizes new knowledge and advances in EV applications. Moreover, we highlight recommendations for future EV-related research.

Understanding the Role of Fibroblasts following a 3D Tumoroid Implantation for Breast Tumor Formation

An understanding of the participation and modulation of fibroblasts during tumor formation and growth is still unclear. Among many speculates, one might be the technical challenge to reveal the versatile function of fibroblasts in tissue complexity, and another is the dynamics in tissue physiology and cell activity. The histology of most solid tumors shows a predominant presence of fibroblasts, suggesting that tumor cells recruit fibroblasts for breast tumor growth. In this review paper, therefore, the migration, activation, differentiation, secretion, and signaling systems that are associated with fibroblasts and cancer-associated fibroblasts (CAFs) after implantation of a breast tumoroid, i.e., a lab-generated tumor tissue into an animal, are discussed.

Diabetic wound healing in soft and hard oral tissues

There is significant interest in understanding the cellular mechanisms responsible for expedited healing response in various oral tissues and how they are impacted by systemic diseases. Depending upon the types of oral tissue, wound healing may occur by predominantly re-eptihelialization, by re-epithelialization with substantial new connective tissue formation, or by a a combination of both plus new bone formation. As a result, the cells involved differ and are impacted by systemic diaseses in various ways. Diabetes mellitus is a prevalent metabolic disorder that impairs barrier function and healing responses throughout the human body. In the oral cavity, diabetes is a known risk factor for exacerbated periodontal disease and delayed wound healing, which includes both soft and hard tissue components. Here, we review the mechanisms of diabetic oral wound healing, particularly on impaired keratinocyte proliferation and migration, altered level of inflammation, and reduced formation of new connective tissue and bone. In particular, diabetes inhibits the expression of mitogenic growth factors whereas that of pro-inflammatory cytokines is elevated through epigenetic mechanisms. Moreover, hyperglycemia and oxidative stress induced by diabetes prevents the expansion of mesengenic cells that are involved in both soft and hard tissue oral wounds. A better understanding of how diabetes influences the healing processes is crucial for the prevention and treatment of diabetes-associated oral complications.

Diabetic wound healing: The impact of diabetes on myofibroblast activity and its potential therapeutic treatments

Diabetes is a systemic disease in which the body cannot regulate the amount of sugar, namely glucose, in the blood. High glucose toxicity has been implicated in the dysfunction of diabetic wound healing, following insufficient production (Type 1) or inadequate usage (Type 2) of insulin. Chronic non-healing diabetic wounds are one of the major complications of both types of diabetes, which are serious concerns for public health and can impact the life quality of patients significantly. In general, diabetic wounds are characterized by deficient chemokine production, an unusual inflammatory response, lack of angiogenesis and epithelialization, and dysfunction of fibroblasts. Increasing scientific evidence from available experimental studies on animal and cell models strongly associates impaired wound healing in diabetes with dysregulated fibroblast differentiation to myofibroblasts, interrupted myofibroblast activity, and inadequate extracellular matrix production. Myofibroblasts play an important role in tissue repair by producing and organizing extracellular matrix and subsequently promoting wound contraction. Based on these studies, hyperglycaemic conditions can interfere with cytokine signalling pathways (such as growth factor-β pathway) affecting fibroblast differentiation, alter fibroblast apoptosis, dysregulate dermal lipolysis, and enhance hypoxia damage, thus leading to damaged microenvironment for myofibroblast formation, inappropriate extracellular matrix modulation, and weakened wound contraction. In this review, we will focus on the current available studies on the impact of diabetes on fibroblast differentiation and myofibroblast function, as well as potential treatments related to the affected pathways.

Magnetic fields as a potential therapy for diabetic wounds based on animal experiments and clinical trials

Diabetes mellitus (DM) is a chronic metabolic disorder with various complications that poses a huge worldwide healthcare burden. Wounds in diabetes, especially diabetic foot ulcers (DFUs), are difficult to manage, often leading to prolonged wound repair and even amputation. Wound management in people with diabetes is an extremely clinical and social concern. Nowadays, physical interventions gain much attention and have been widely developed in the fields of tissue regeneration and wound healing. Magnetic fields (MFs)-based devices are translated into clinical practice for the treatment of bone diseases and neurodegenerative disorder. This review attempts to give insight into the mechanisms and applications of MFs in wound care, especially in improving the healing outcomes of diabetic wounds. First, we discuss the pathological conditions associated with chronic diabetic wounds. Next, the mechanisms involved in MFs' effects on wounds are explored. At last, studies and reports regarding the effects of MFs on diabetic wounds from both animal experiments and clinical trials are reviewed. MFs exhibit great potential in promoting wound healing and have been practised in the management of diabetic wounds. Further studies on the exact mechanism of MFs on diabetic wounds and the development of suitable MF-based devices could lead to their increased applications into clinical practice.

Ski promotes proliferation and inhibits apoptosis in fibroblasts under high-glucose conditions via the FoxO1 pathway

OBJECTIVES

The present study clarified the role and signalling pathway of Ski in regulating proliferation and apoptosis in fibroblasts under high-glucose (HG) conditions.

MATERIALS AND METHODS

The proliferation and apoptosis of rat primary fibroblasts were assessed using EdU incorporation and TUNEL assays. The protein and phosphorylation levels of the corresponding factors were measured using immunofluorescence staining and Western blotting. Immunoprecipitation was used to determine the interactions between Ski and FoxO1 or Ski and HDAC1. The Ski protein was overexpressed via recombinant adenovirus transfection, and FoxO1 and HDAC1 were knocked down using targeted small-interfering RNA.

RESULTS

The present study found that HG inhibited fibroblast proliferation, increased apoptosis and reduced Ski levels in rat primary fibroblasts. Conversely, increasing Ski protein levels alleviated HG-induced proliferation inhibition and apoptosis promotion. Increasing Ski protein levels also increased Ski binding to FoxO1 to decrease FoxO1 acetylation, and interfering with FoxO1 caused loss of the regulatory effect of Ski in fibroblasts under HG. Increasing Ski protein levels decreased FoxO1 acetylation via HDAC1-mediated deacetylation.

CONCLUSIONS

Therefore, these findings confirmed for the first time that Ski regulated fibroblast proliferation and apoptosis under HG conditions via the FoxO1 pathway.

Bone regeneration in a mouse model of type 1 diabetes: Influence of sex, vitamin D3, and insulin

AIM

This study set forth a question: are there any differences in bone responses to insulin and/or vitamin D3 treatment in female and male type 1 diabetic (T1D) mice?

MAIN METHODS

To address this issue, a non-critical sized femur defect was created in streptozotocin (STZ)-T1D mice. Control non-diabetic and T1D female and male mice received: saline; vitamin D3; insulin; or vitamin D3 plus insulin, for 21 days.

KEY FINDINGS

Female and male T1D mice showed impaired bone healing, as indicated by histological and micro-computed tomography (micro-CT) analysis. Vitamin D3 or insulin improved the bone regeneration in T1D mice, irrespective of sex. Vitamin D3 plus insulin did not exhibit any additional effects. There were no differences regarding the numbers of TRAP-stained osteoclasts in either evaluated groups. The osteoblast-related gene osterix was upregulated in vitamin D3-treated male T1D mice, as revealed by RT-qPCR. Female T1D mice treated with vitamin D3, insulin, or vitamin D3 plus insulin presented an increased expression of insulin growth factor-1 (IGF-1) mRNA. Conversely, IGF-1 mRNA levels were reduced by the same treatments in male TD1 mice.

SIGNIFICANCE

Altogether, the results suggested that T1D similarly delayed the osseous healing in female and male mice, with beneficial effects for either vitamin D3 or insulin in T1D mice of both sexes. However, data indicated marked sex differences regarding the expression of genes implicated in bone formation, in T1D mice treated with vitamin D3 and/or insulin.

Selected conditions associated with an increased incidence of incisional hernia: A review of molecular biology

BACKGROUND

Incisional hernias (IH) following a laparotomy, on average, occur in 10-20% of patients, however, little is known about its molecular basis. Thus, a better understanding of the molecular mechanisms could lead to the identification of key target(s) to intervene pre-and post-operatively.

METHODS

We examined the current literature describing the molecular mechanisms of IH and overlap these factors with smoking, abdominal aortic aneurysm, obesity, diabetes mellitus, and diverticulitis.

RESULTS

The expression levels of collagen I and III, matrix metalloproteinases, and tissue inhibitors of metalloproteases are abnormal in the extracellular matrix (ECM) of IH patients and ECM disorganization has an overlap with these comorbid conditions.

CONCLUSION

Understanding the pathophysiology of IH development and associated risk factors will allow physicians to identify patients that may be at increased risk for IH and to possibly act preemptively to decrease the incidence of IH.

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.

Advanced Glycation End Products (AGEs) Induce Apoptosis of Fibroblasts by Activation of NLRP3 Inflammasome via Reactive Oxygen Species (ROS) Signaling Pathway

Background

Type 2 diabetes impairs the healing process and induces apoptosis of fibroblasts, which are thought to be involved in this process. We investigated the possible mechanisms involved in AGEs-induced apoptosis of human dermal fibroblasts.

Material/Methods

We examined the expression of apoptosis-related proteins in fibroblasts isolated from human diabetic wounds. Human dermal fibroblasts exposed to AGEs were used to study the links among apoptosis, ROS, and NLRP3 inflammasome activation. Signaling mechanisms were evaluated by preincubating the cells with appropriate inhibitors. Cleaved caspase-8, cleaved caspase-3, BAX, Bcl-2, and NLRP3 inflammasome expression were measured by Western blot analysis. ROS generation, cell viability, and cell apoptosis were assessed.

Results

We observed a higher level of cleaved caspase-8 and cleaved caspase-3 expression in fibroblasts isolated from human diabetic wounds compared with controls. AGEs decreased the proliferation of cells in a concentration-dependent and time-dependent manner. The exposure of fibroblasts to AGEs significantly increased the number of cells in early and late apoptosis stages. AGES-induced human dermal fibroblasts showed high expressions of cleaved caspase3, cleaved caspase8, and Bax. Treatment with AGEs induced the expression of NLRP3, caspase-1, and ASC. AGES-induced apoptosis was blocked by BAY 11–7082, an inhibitor of the NLRP3 inflammasome. AGEs increased the production of ROS in fibroblasts, and its apoptogenic effect was blocked by NAC.

Conclusions

AGEs cause apoptosis of fibroblasts by inducing the generation of ROS and activating the NLRP3 inflammasome. In vivo experiments are needed to confirm these results.

Potential of Distilled Liquid Smoke Derived from Coconut (Cocos nucifera L) Shell for Traumatic Ulcer Healing in Diabetic Rats

Objective Distilled liquid smoke (DLS) is a result of coconut processing by-product that not only serves as a natural food preservative but also has a promising therapeutic effect. The healing potential of DLS derived from coconut ( Cocos nucifera L) shell was investigated on a traumatic ulcer with the diabetic rat.

Materials and Methods DLS was analyzed the component by gas chromatograph mass spectrometry. Diabetic condition was induced by alloxan in 55 male Wistar rats. Ten mm of traumatic ulcer was made along the labial fornix incisive inferior after the diabetic condition was confirmed. Then DLS coconut shell, benzydamine hydrochloride, and sterile distilled water were applied topically for 3, 5, and 7 days. The potential healing was evaluated based on the expression of nuclear factor kappa beta (NFκB) and tumor necrosis factor alpha (TNF-α) on macrophages using immunohistochemical staining and the amount of collagen using Masson Trichome staining. The difference between each group was analyzed using one-way analysis of variance. The least significant difference test is used to determine the significant difference ( p < 0.05).

Results The major compounds found were phenol (36.6%), 2-methoxyphenol (guaiacol) (25.2%), furfural (17.8%), and 4-ethyl-2-methoxyphenol (3.5%) with 28 other minor constituents. The lowest NFκB and TNF-α expression on macrophage was observed by topical application of DLS derived from coconut shell for 3, 5, and 7 days of treatment. The amount of collagen was increased and indicated by the highest result of DLS compared to others.

Conclusion The DLS derived from coconut ( Cocos nucifera L) shell was able to improve traumatic ulcer healing in a person with diabetes.

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.

IL-7 overexpression enhances therapeutic potential of rat bone marrow mesenchymal stem cells for diabetic wounds

This study was aimed to enhance the healing potential of rat bone marrow mesenchymal stem cells against chronic diabetic wounds through interleukin-7 (IL-7) transfection. IL-7 plays an important role in wound healing and acts as a survival factor in some cell types. This study involves isolation, propagation, and characterization of mesenchymal stem cells (MSCs) and their modification with IL-7 gene via retroviral transfection. Transfected MSCs were assessed for their effect on angiogenic genes by qPCR. Wound healing potential of transfected MSCs was analyzed by scratch assay in vitro and by transplanting these cells in rat diabetic wound models in vivo. Wound area was measured for a period of 15 days and subsequent histological analysis was performed. qPCR results showed increased expression of IL-7 gene (p ≤ 0.05) and also principal angiogenic genes, vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), VEGF receptor 1 (FLT-1), and VEGF receptor 2 (FLK-1) (p ≤ 0.05). Neuropilin-1 (NRP-1) did not show any significant change. In vitro analysis of IL-7 MSCs showed intense cell-cell connections and tube formation as compared to the normal MSCs. Rate of wound closure was more (p ≤ 0.001) in case of diabetic group transplanted with IL-7 MSCs. Histological examination revealed enhanced vascular supply in skin tissues of diabetic animals transplanted with IL-7 transfected MSCs as compared to normal MSCs. Immunohistochemical results showed significantly higher expression of IL-7 (p ≤ 0.001) and α-smooth muscle actin(p ≤ 0.001) in the tissue sections of IL-7 transfected group as compared to normal MSCs and the diabetic control group; the latter indicates increase in the number of blood vessels. It is concluded from this study that IL-7 overexpression in MSCs can enhance the healing potential of MSCs and aid in wound closure in diabetic animals through the induction of angiogenic genes.

Targeting epigenetic mechanisms in diabetic wound healing

Impaired wound healing is a major secondary complication of type 2 diabetes that often results in limb loss and disability. Normal tissue repair progresses through discrete phases including hemostasis, inflammation, proliferation, and remodeling. In diabetes, normal progression through these phases is impaired resulting in a sustained inflammatory state and dysfunctional epithelialization in the wound. Due to their plasticity, macrophages play a critical role in the transition from the inflammation phase to the proliferation phase. Diabetes disrupts macrophage function by impairing monocyte recruitment to the wound, reducing phagocytosis, and prohibiting the transition of inflammatory macrophages to an anti-inflammatory state. Diabetes also impedes keratinocyte and fibroblast function during the later phases resulting in impaired epithelialization of the wound. Several recent studies suggest that altered epigenetic regulation of both immune and structural cells in wounds may influence cell phenotypes and healing, particularly in pathologic states, such as diabetes. Specifically, it has been shown that macrophage plasticity during wound repair is partly regulated epigenetically and that diabetes alters this epigenetic regulation and contributes to a sustained inflammatory state. Epigenetic regulation is also known to regulate keratinocyte and fibroblast function during wound repair. In this review, we provide an introduction to the epigenetic mechanisms that regulate tissue repair and highlight recent findings that demonstrate, how epigenetic events are altered during the course of diabetic wound healing.

Von Hippel-Lindau (VHL) Protein Antagonist VH298 Improves Wound Healing in Streptozotocin-Induced Hyperglycaemic Rats by Activating Hypoxia-Inducible Factor- (HIF-) 1 Signalling

AIMS

The purpose of the present research is to investigate the effects of the VHL protein antagonist, VH298, on functional activities of fibroblasts and vascular endothelial cells and the effects on the wound healing process in a streptozotocin-induced hyperglycaemic rat model.

METHODS

HIF-1α and hydroxy-HIF-1α protein levels in VH298-treated rat fibroblasts (rFb) were measured by immunoblotting, rFb proliferation was detected by the CCK-8 assay, and mRNA levels of related genes were measured by quantitative RT-PCR. In vitro wound healing was simulated by the scratch test; angiogenesis was measured by the human umbilical vein endothelial cell (hUVEC) tube formation assay. VH298 or PBS was locally injected into wounds in rat models with streptozotocin- (STZ-) induced hyperglycaemia, the wound tissues were harvested, and haematoxylin-eosin (HE) and Masson trichrome staining and immunohistochemical processes were conducted.

RESULTS

HIF-1α and hydroxy-HIF-1α levels increased in VH298-treated rFb, in a time- and dose-dependent manner. Thirty micromolar VH298 could significantly increase cell proliferation, angiogenesis, and gene expression of type I collagen-α1 (Col1-α1), vascular endothelial growth factor A (VEGF-A), and insulin-like growth factor 1 (IGF-1). The VH298-treated wound had a better healing pattern, activation of HIF-1 signalling, and vascularization.

CONCLUSIONS

Taken together, VH298 activated the HIF-1 signalling pathway by stabilizing both HIF-1α and hydroxy-HIF-1α. VH298 enhanced rFb functions, promoted hUVEC angiogenesis, and accelerated wound healing in the rat model mimicking diabetes mellitus.

Efficacy of Cellular Therapy for Diabetic Foot Ulcer: A Meta-Analysis of Randomized Controlled Clinical Trials

Diabetes mellitus is a widely spread chronic disease with growing incidence worldwide, and diabetic foot ulcer is one of the most serious complications of diabetes. Cellular therapy has shown promise in the management of diabetic foot ulcer in many preclinical experiments and clinical researches. Here, we performed a meta-analysis to evaluate the efficacy and safety of cellular therapy in the management of diabetic foot ulcer. We systematically searched PubMed, MEDLINE, EMBASE, and Cochrane Library databases from inception to May 2017 for randomized controlled trials assessing the efficacy of cellular therapy in diabetic foot ulcer, and a meta-analysis was conducted. A total of 6 randomized controlled clinical trials involving 241 individuals were included in this meta-analysis. The results suggested that cellular therapy could help accelerating the healing of diabetic foot ulcer, presented as higher ankle-brachial index (mean difference = 0.17, 95% confidence interval [CI] = 0.11 to 0.23), higher transcutaneous oxygen pressure (standardized mean difference [SMD] = 1.43; 95% CI, 1.09– to 1.78), higher ulcer healing rate (relative risk [RR] = 1.78; 95% CI, 1.41 to 2.25), higher amputation-free survival (RR = 1.25; 95% CI, 1.11 to 1.40), and lower scale of pain (SMD = −1.69; 95% CI, −2.05 to −1.33). Furthermore, cellular therapy seemed to be safe, with no serious complications and low risk of short-term slight complications. Cellular therapy could accelerate the rate of diabetic foot ulcer healing and may be more efficient than standard therapy for diabetic foot treatment.

Effect of diabetes on collagen metabolism and hypoxia in human gingival tissue: a stereological, histopathological, and immunohistochemical study

Diabetes mellitus and periodontitis are chronic inflammatory diseases that disrupt soft tissue metabolism. The diseases separately or together increase apoptosis in gingival fibroblast cells and reduce cell renewal. We investigated the effects of diabetes and periodontitis on the composition and structure of gingival connective tissue. We used gingival biopsies from 16 healthy individuals (control group, C), 16 type 2 diabetic patients with chronic periodontitis (diabetes + periodontitis group, D + P) and 16 healthy chronic periodontitis patients (periodontitis group, P). Biopsies were obtained under local anesthesia. Clinical attachment level (CAL), gingival index (GI) and plaque index (PI) were measured prior to gingival biopsies. Fibroblast cells were counted stereologically. Inflammatory cells were counted histomorphometrically. Hypoxia-inducible factor (HIF)-1α, lysyl hydroxylase (PLOD-2), neutrophil collagenase (MMP-8), and vascular endothelial growth factor (VEGF) levels were evaluated immunohistochemically. CAL, GI and PI for the C group were lower than for the other groups (p < 0.05). Fibroblast cell counts were lower for the D + P group than for the other groups (p < 0.05). Diabetes increased inflammatory cell numbers in the D and D + P groups compared to the C and P groups. MMP-8 levels were higher for the D + P group than for the other groups. VEGF was elevated in both the P and D + P groups compared to the C group, while HIF-1α and PLOD-2 levels were comparable. Diabetes increased tissue destruction and inflammation, and decreased fibroblast cell numbers without affecting collagen crosslinking and HIF-1α levels.

Role of myofibroblasts in normal and pathological periodontal wound healing

Myofibroblasts represent specific subpopulations of cells with important roles in tissue remodeling in both health and disease. They are not usually found in resting healthy tissues. However, they increase in number during the proliferative phase of wound healing. In these conditions, myofibroblasts secrete and organize different molecular components of the extracellular matrix that with time will reconstitute and hopefully regenerate the damaged tissue. Importantly, these cell populations must be eliminated after wound healing has been completed. However, deficiencies in their differentiation or the persistence of this cell population has been associated with the development of delayed wound healing and fibrosis, respectively. In the present review, we analyze the involvement of myofibroblasts in periodontal wound healing and their potential contribution to tissue homeostasis and disease.

High glucose-induced oxidative stress impairs proliferation and migration of human gingival fibroblasts

Delayed gingival wound healing is widely observed in periodontal patients with diabetes. However, the molecular mechanisms of the impaired function of gingival fibroblasts in diabetes remain unclear. The purpose of this study was to investigate changes in the properties of human gingival fibroblasts (HGFs) under high-glucose conditions. Primary HGFs were isolated from healthy gingiva and cultured with 5.5, 25, 50, and 75 mM glucose for 72 h. In vitro wound healing, 5-ethynyl-2′-deoxyuridine (EdU), and water-soluble tetrazolium salt (WST-8) assays were performed to examine cell migration and proliferation. Lactase dehydrogenase (LDH) levels were measured to determine cytotoxicity. The mRNA expression levels of oxidative stress markers were quantified by real-time PCR. Intracellular reactive oxygen species (ROS) were also measured in live cells. The antioxidant N-acetyl-l-cysteine (NAC, 1 mM) was added to evaluate the involvement of ROS in the glucose effect on HGFs. As a result, the in vitro wound healing assay showed that high glucose levels significantly reduced fibroblast migration and proliferation at 6, 12, 24, 36, and 48 h. The numbers of cells positive for EdU staining were decreased, as was cell viability, at 50 and 75 mM glucose. A significant increase in LDH was proportional to the glucose concentration. The mRNA levels of heme oxygenase-1 and superoxide dismutase-1 and ROS levels were significantly increased in HGFs after 72 h of exposure to 50 mM glucose concentration. The addition of NAC diminished the inhibitory effect of high glucose in the in vitro wound healing assay. The results of the present study show that high glucose impairs the proliferation and migration of HGFs. Fibroblast dysfunction may therefore be caused by high glucose-induced oxidative stress and may explain the delayed gingival wound healing in diabetic patients.

Role of Forkhead Box O (FOXO) transcription factor in aging and diseases

Fork head box O (FOXO) transcription factor is a key player in an evolutionarily conserved pathway. The mammalian FOXO family consists of FOXO1, 3, 4 and 6, are highly similar in their structure, function and regulation. To maintain optimum body function, the organisms have developed complex mechanisms for homeostasis. Importantly, it is well known that when these mechanisms dysregulate it results in the development of age-related disease. FOXO proteins are involved in a diverse cellular function and also have clinical significance including cell cycle arrest, cell differentiation, tumour suppression, DNA repair, longevity, diabetic complications, immunity, wound healing, regulation of metabolism and thus treatment of several types of diseases. By the combinations of post-translational modifications FOXO's serve as a 'molecular code' to sense external stimuli and recruit it as to specific regions of the genome and provide an integrated cellular response to changing physiological conditions. Akt/Protein kinase B a signaling pathway as a main regulator of FOXO to perform a diverse function in organisms. The present review summarizes the molecular and clinical aspects of FOXO transcription factor. And also elaborate the interaction of FOXO with the nucleosome remodelling complex to target genes, which is essential to cellular homeostasis.

Redox Signaling in Diabetic Wound Healing Regulates Extracellular Matrix Deposition

SIGNIFICANCE

Impaired wound healing is a major complication of diabetes, and can lead to development of chronic foot ulcers in a significant number of patients. Despite the danger posed by poor healing, very few specific therapies exist, leaving patients at risk of hospitalization, amputation, and further decline in overall health. Recent Advances: Redox signaling is a key regulator of wound healing, especially through its influence on the extracellular matrix (ECM). Normal redox signaling is disrupted in diabetes leading to several pathological mechanisms that alter the balance between reactive oxygen species (ROS) generation and scavenging. Importantly, pathological oxidative stress can alter ECM structure and function.

CRITICAL ISSUES

There is limited understanding of the specific role of altered redox signaling in the diabetic wound, although there is evidence that ROS are involved in the underlying pathology.

FUTURE DIRECTIONS

Preclinical studies of antioxidant-based therapies for diabetic wound healing have yielded promising results. Redox-based therapeutics constitute a novel approach for the treatment of wounds in diabetes patients that deserve further investigation. Antioxid. Redox Signal. 27, 823-838.

Is caffeic acid phenethyl ester more protective than doxycycline in experimental periodontitis?

BACKGROUND AND OBJECTIVES

Host modulation therapies (anti-inflammatory drugs, bone-stimulating agents, anti-proteinase etc.) target the inhibition or stabilization of tissue breakdown. The aim of the present study was to evaluate the effects of caffeic acid phenethyl ester (CAPE) and/or low dose doxycycline (LDD) administrations on alveolar bone loss (ABL), serum cytokines and gingival apoptosis, as well as the levels of oxidants and anti-oxidants in rats with ligature-induced periodontitis.

MATERIAL AND METHODS

The animals were randomly divided into five groups: Group C (periodontally healthy), Group PC (Periodontitis+CAPE), Group PD (Periodontitis+LDD), Group PCD (Periodontitis+CAPE+LDD), Group P (Periodontitis). Experimental periodontitis was induced for 14days. Levels of ABL, and the serum cytokines, interleukin (IL)-1 β, IL-6, tumor necrosis factor-α (TNF-α) and IL-10 were assessed as were the levels of the oxidants and anti-oxidants, malondialdehyde (MDA), glutathione (GSH) and glutathione peroxidase (GSH-Px), and levels of gingival apoptosis.

RESULTS

The lowest ABL levels was evident in the PC group, among the experimental groups. There was also less inflammatory infiltration in the PC group than the PD group. IL-1β, IL-6, and IL-10 were lower in the PC group and higher in the P group in comparison to the levels in the other experiment groups. TNF-α levels in the PD group were higher than levels in the PC and PCD groups. The PC and PCD groups did not differ from the C group in regard to MDA levels. The highest GSH-Px level was found in the PC group. Gingival apoptosis in the PC group was not only lower than the PD and PCD groups, but also lower than in the C group.

CONCLUSION

The present study suggests that CAPE has more anti-inflammatory, anti-oxidant and anti-apoptotic effects than LDD, with no additive benefits of a CAPE+LDD combination being evident in rats with periodontitis.

Diabetic ulcer regeneration: stem cells, biomaterials, growth factors

The impairment of ulcer wound healing in diabetic patients is a vital clinical problem affecting millions of patients. Several clinical and basic science studies have demonstrated that stem cell therapy, to be effective in healing diabetic ulcer. Furthermore, these ulcer wounds may be healed from molecular maneuvering of growth factors to improve microcirculation within the ulcer wound. In addition, ulcer wound dressings may be employed as medicated systems, through the delivery of drugs, growth factors, peptides and stem cells. These dressing materials can include natural, modified and synthetic polymers, as well as their mixtures or combinations. This review paper will give a summary of some of the recent advances on the application of stem cells, biomaterials and growth factors in the treatment of diabetic ulcer wound.

Effects of Dimethyloxalylglycine-Embedded Poly(ε-caprolactone) Fiber Meshes on Wound Healing in Diabetic Rats

Impaired wound healing in diabetic patients is associated with altered inflammatory responses, poor angiogenesis, deficient extracellular matrix (ECM) component, and peripheral neuropathy. To develop a wound dressing that is capable of the controlled delivery of bioactive small molecules that can improve diabetic wound healing, dimethyloxalylglycine (DMOG)-embedded poly(ε-caprolactone) (PCL) fiber (PCLF/DMOG) meshes are fabricated by electrospinning, and the effects of the PCLF/DMOG meshes on wound healing in diabetic rats are evaluated. Electrospun PCLF/DMOG meshes increase not only the wound closure, re-epithelialization ratio, epithelial maturation (K-10-positive epidermis), and collagen-positive area but also the numbers of angiogenic marker (CD-31)-positive and neuronal marker (neurofilament)-positive cells compared to PCLF (p < 0.05). In in vitro examinations, RAW264.7 macrophages grown on PCLF/DMOG meshes enhance the expression of growth factors (IGF-1, HB-EGF, and NGF) and anti-inflammatory factors (TGF-β1 and IL-4) but decrease that of pro-inflammatory factors (IL-1β and IL-6). Keratinocyte migration is increased by conditioned media from the cultures of the macrophages grown either in the presence of DMOG or on PCLF/DMOG. Collectively, these results indicate that PCLF/DMOG meshes promote impaired wound healing in diabetic rats by modulating macrophage responses, enhancing angiogenesis and nerve innervation, and improving ECM synthesis.

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.

Activation of α7nAChR Promotes Diabetic Wound Healing by Suppressing AGE-Induced TNF-α Production

Diabetes frequently presents accumulation of advanced glycation end products (AGEs), which might induce excessive TNF-α production from macrophages to cause impaired wound healing. Recent studies have shown that activation of α7 nicotinic acetylcholine receptor (α7nAChR) on macrophages efficiently suppressed TNF-α synthesis. The aim of this study was to investigate the accumulation of AGEs in the wounds and determine whether PNU282987, an α7nAChR agonist, can improve wound repair by inhibiting AGE-mediated TNF-α production in a streptozotocin (STZ)-induced diabetic mouse model. Animals were assigned into four groups: wounded control group, wounded diabetic group, wounded diabetic group treated intraperitoneally with PNU282987, or wounded diabetic group treated intraperitoneally with vehicle. Compared with the non-diabetic control mice, the diabetic mice exhibited delayed wound healing that was characterized by elevated accumulation of AGEs, increased TNF-α level and macrophage infiltration, and decreased fibroblast number and collagen deposition at the late stage of repair. Besides, macrophages of diabetic wounds showed expression of α7nAChR. During late repair, PNU282987 treatment of diabetic mice significantly reduced the level of TNF-α, accelerated wound healing, and elevated fibroblast number and collagen deposition. To investigate the cellular mechanism of these observations, RAW 264.7 cells, a macrophage cell line, were incubated with AGEs in the presence or absence of PNU282987. TNF-α production from AGE-stimulated macrophages was significantly decreased by PNU282987 in a dose-dependent manner. Furthermore, PNU282987 significantly inhibited AGE-induced nuclear factor-κB (NF-κB) activation and receptor for AGE (RAGE) expression. These results strongly suggest that activating α7nAChR can promote diabetic wound healing by suppressing AGE-induced TNF-α production, which may be closely associated with the blockage of NF-κB activation in macrophages.

A review of the evidence for pathogenic mechanisms that may link periodontitis and diabetes

AIMS

To review the evidence for the molecular and cellular processes that may potentially link periodontal disease and diabetes. The pathogenic roles of cytokines and metabolic molecules (e.g. glucose, lipids) are explored and the role of periodontal bacteria is also addressed. Paradigms for bidirectional relationships between periodontitis and diabetes are discussed and opportunities for elaborating these models are considered.

METHODS

Database searches were performed using MeSH terms, keywords, and title words. Studies were evaluated and summarized in a narrative review.

RESULTS

Periodontal microbiota appears unaltered by diabetes and there is little evidence that it may influence glycaemic control. Small-scale clinical studies and experiments in animal models suggest that IL-1β, TNF-α, IL-6, OPG and RANKL may mediate periodontitis in diabetes. The AGE-RAGE axis is likely an important pathway of tissue destruction and impaired repair in diabetes-associated periodontitis. A role for locally activated pro-inflammatory factors in the periodontium, which subsequently impact on diabetes, remains speculative.

CONCLUSION

There is substantial information on potential mechanistic pathways which support a close association between diabetes and periodontitis, but there is a real need for longitudinal clinical studies using larger patient groups, integrated with studies of animal models and cells/tissues in vitro.

Management of diabolical diabetes mellitus and periodontitis nexus: Are we doing enough?

Periodontitis is the commonest oral disease affecting population worldwide. This disease is notorious for the devastation of tooth supporting structures, ensuing in the loss of dentition. The etiology for this disease is bacterial biofilm, which accumulates on the teeth as dental plaque. In addition to the biofilm microorganisms, other factors such as environmental, systemic and genetic are also responsible in progression of periodontitis. Diabetes mellitus (DM) is metabolic disorder which has an impact on the global health. DM plays a crucial role in the pathogenesis of periodontitis. Periodontitis is declared as the “sixth” major complication of DM. Evidence based literature has depicted an enhanced incidence and severity of periodontitis in subjects with DM. A “two way” relationship has been purported between periodontitis and DM. Mutual management of both conditions is necessary. Periodontal therapy (PT) may assist to diminish the progression of DM and improve glycemic control. Various advanced technological facilities may be utilized for the purpose of patient education and disease management. The present paper clarifies the etio-pathogenesis of periodontitis, establishing it as a complication of DM and elaborating the various mechanisms involved in the pathogenesis. The role of PT in amelioration of DM and application of digital communication will be discussed. Overall, it is judicious to create an increased patient cognizance of the periodontitis-DM relationship. Conjunctive efforts must be undertaken by the medical and oral health care professionals for the management of periodontitis affected DM patients.

Bilirubin modulated cytokines, growth factors and angiogenesis to improve cutaneous wound healing process in diabetic rats

Bilirubin has shown cutaneous wound healing potential in some preliminary studies. Here we hypothesize that bilirubin facilitates wound healing in diabetic rats by modulating important healing factors/candidates and antioxidant parameters in a time-dependent manner. Diabetes was induced in male Wistar rats by streptozotocin. In all diabetic rats wounds were created under pentobarbitone anesthesia. All the rats were divided into two groups, of which one (control) was treated with ointment base and other with bilirubin ointment (0.3%). Wound closer measurement and tissue collection were done on days 3, 7, 14 and 19 post-wounding. The relative expressions of hypoxia inducible factor-1 alpha (HIF-1α), vascular endothelial growth factor (VEGF), stromal cell-derived factor-1 alpha (SDF-1α), transforming growth factor- beta1 (TGF-β1()), tumor necrosis factor-α (TNF-α) and interlukin-10 (IL-10) mRNA and proteins and the mRNA of interlukin-1 beta (IL-1β) and matrix metalloprteinase-9 (MMP-9) were determined in the wound tissues. CD-31 staining and collagen content were evaluated by immunohistochemistry and picrosirius red staining, respectively. Histopathological changes were assessed by H&E staining. The per cent wound closer was significantly higher from day 7 onwards in bilirubin-treated rats. HIF-1α, VEGF, SDF-1α, TGF-β1, IL-10 mRNA and protein levels were significantly higher on days 3, 7 and 14 in bilirubin-treated rats. The mRNA expression and protein level of TNF-α and the mRNA of IL-1β and MMP-9 were progressively and markedly reduced in bilirubin-treated rats. The collagen deposition and formation of blood vessels were greater in bilirubin-treated rats. Bilirubin markedly facilitated cutaneous wound healing in diabetic rats by modulating growth factors, cytokines, neovasculogenesis and collagen contents to the wound site. Topical application of bilirubin ointment might be of great use in cutaneous wound healing in diabetic patients.