Tumor necrosis factor-alpha mediates diabetes-enhanced apoptosis of matrix-producing cells and impairs diabetic healing

Application of decellularized tilapia skin in rabbit urethral reconstruction: an experimental study

Background

In urethral reconstruction, autologous tissue grafts are subject to various limitations. Decellularized tissue has attracted significant interest in tissue engineering (TE) and regenerative medicine due to great biocompatibility and bioactivity. We investigated the effect of decellularized tilapia skin (DTS) in a rabbit urethral defect model to explore its feasibility and effectiveness as a TE construction for urethral reconstruction.

Methods

Fresh tilapia skins were decellularized and verified through its residual deoxyribonucleic acid (DNA) content measurement. The physical properties and degradation profile of DTS were characterized as well. Finally, we established a rabbit urethral defect model and evaluated the effect of DTS on urethral defect healing through pathological examination and immunohistochemistry (IHC) staining.

Results

The residual DNA content in the DTS was 32.94 ng/mg. Electron microscopy showed that the DTS retained its three-dimensional structure. In vitro, degradation experiments showed that DTS degraded at a faster rate than that of small intestinal submucosa (SIS). After implantation of the DTS, the penile tissue was well repaired. In the early stage of tissue repair, the tissue was gradually replaced by new collagen. In addition, smooth muscle content was significantly increased. No significant immune rejection was observed in the tissues during the repair process and the inflammatory response was significantly milder than other group. Nevertheless, angiogenesis markers, the numbers of blood vessels and blood vessel area in DTS intervention groups were the highest at 4 weeks post-implantation.

Conclusions

DTS could degrade gradually during urethral reconstruction and demonstrated its better biocompatibility in terms of de novo tissue morphology, microanatomy of tissues, severity of inflammation, collagen deposition and angiogenesis in defect region vs. its match control groups. As an excellent TE material, it is expected to be used in clinical urethral reconstruction in future.

Inflammation and mechanical force-induced bone remodeling

Periodontitis arises from imbalanced host-microbe interactions, leading to dysbiosis and destructive inflammation. The host's innate and adaptive immune responses produce pro-inflammatory mediators that stimulate destructive events, which cause loss of alveolar bone and connective tissue attachment. There is no consensus on the factors that lead to a conversion from gingivitis to periodontitis, but one possibility is the proximity of the inflammation to the bone, which promotes bone resorption and inhibits subsequent bone formation during coupled bone formation. Conversely, orthodontic tooth movement is triggered by the mechanical force applied to the tooth, resulting in bone resorption on the compression side and new bone formation on the tension side. However, the environment around orthodontic brackets readily retains dental plaque and may contribute to inflammation and bone remodeling. The immune, epithelial, stromal, endothelial and bone cells of the host play an important role in setting the stage for bone remodeling that occurs in both periodontitis and orthodontic tooth movement. Recent advancements in single-cell RNA sequencing have provided new insights into the roles and interactions of different cell types in response to challenges. In this review, we meticulously examine the functions of key cell types such as keratinocytes, leukocytes, stromal cells, osteocytes, osteoblasts, and osteoclasts involved in inflammation- and mechanical force-driven bone remodeling. Moreover, we explore the combined effects of these two conditions: mechanical force-induced bone remodeling combined with periodontal disease (chronic inflammation) and periodontally accelerated osteogenic orthodontics (acute transient inflammation). This comprehensive review enhances our understanding of inflammation- and mechanical force-induced bone remodeling.

Deciphering the Dysregulating IGF-1-SP1-CD248 Pathway in Fibroblast Functionality during Diabetic Wound Healing

Reduced fibroblast activity is a critical factor in the progression of diabetic ulcers. CD248, a transmembrane glycoprotein prominently expressed in activated fibroblasts, plays a pivotal role in wound healing. However, the role of CD248 in diabetic wound healing and the CD248 regulatory pathway remains largely unexplored. Our study shows that CD248 expression is significantly reduced in skin wounds from both patients and mice with diabetes. Single-cell transcriptome data analyses reveal a marked reduction of CD248-enriched secretory-reticular fibroblasts in diabetic wounds. We identify IGF-1 as a key regulator of CD248 expression through the protein kinase B/mTOR signaling pathway and the SP1 transcription factor. Overexpression of CD248 enhances fibroblast motility, elucidating the under-representation of CD248-enriched fibroblasts in diabetic wounds. Immunohistochemical staining of diabetic wound samples further confirms low SP1 expression and fewer CD248-positive secretory-reticular fibroblasts. Further investigation reveals that elevated TNFα levels in diabetic environment promotes IGF-1 resistance, and inhibiting IGF-1 induced CD248 expression. In summary, our findings underscore the critical role of the IGF1-SP1-CD248 axis in activating reticular fibroblasts during wound-healing processes. Targeting this axis in fibroblasts could help develop a therapeutic regimen for diabetic ulcers.

Diabetes Mellitus and Periodontal Disease: A New Perspective

First recorded in 1928, people living with diabetes mellitus (DM) are at a three to four times higher risk of developing periodontal disease (PD) than non-diabetics; for those who smoke this risk increases up to ten times. However, many doctors are unaware of this.DM and PD are bidirectionally linked, the one affecting the other and vice versa, although the mechanism is not fully understood and may be linked to chronic infection. PD has an adverse effect on glycaemic control. That improves when periodontitis is successfully treated.Doctors should consider PD when their patients have persistently high glycated haemoglobin (HbA1c) levels, and dentists should consider diabetes or pre-diabetes when they have patients with unstable or progressive periodontitis.Doctors, dentists, and their teams need to share results. A traffic light system of red, amber and green for both medical and dental risks is proposed, and a pro forma designed, so that diabetics themselves can share them with their professional advisors until such times as there are reliable methods of interprofessional communication and a paradigm shift in working practices is achieved.Dentists need to find ways to teach their medical colleagues about the basics of PD, update their medical records, and understand more about medical risks. More research is required.

Type 1 Diabetes Mellitus Patients' Self-perception of Periodontal Diseases

OBJECTIVES

 The study aimed to evaluate type 1 diabetes mellitus (T1DM) patients' self-perceived periodontal health status and to identify the association between periodontal disease (PD) and DM.

MATERIALS AND METHODS

 This cross-sectional study included 113 T1DM children between 3 and 18 years old from the Universiti Teknologi MARA and the University of Malaya. Periodontal health parameters, including plaque index, gingival index, probing pocket depth, simplified basic periodontal examination, and clinical attachment loss, were recorded. Self-perceived periodontal health status was assessed with questionnaires.

STATISTICAL ANALYSIS

 Statistical analysis was performed to evaluate the sensitivity of the questionnaire and the relationship between T1DM and periodontal parameters.

RESULTS

 The median age was 11.4 years. Half of them (50.4%) were females. A total of 83.5% rated their oral condition as good, whereas 27.5% reported a history of gingival bleeding. Clinical examination revealed that 48.7% had healthy gingiva, whereas 47.8% had gingivitis. The question "Do you have bleeding when brushing, flossing, or eating food?" showed good accuracy in the evaluation of PD (p < 0.001).

CONCLUSION

 The questionnaire has a high potential to be used by medical professionals in identifying T1DM patients at risk of PD to guide nondental health care providers in making appropriate referrals to dental services.

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.

Biological macromolecules-based nanoformulation in improving wound healing and bacterial biofilm-associated infection: A review

A chronic wound is a serious complication associated with diabetes mellitus and is difficult to heal due to high glucose levels, oxidative stress, and biofilm-associated microbial infection. The structural complexity of microbial biofilm makes it impossible for antibiotics to penetrate the matrix, hence conventional antibiotic therapies became ineffective in clinical settings. This demonstrates an urgent need to find safer alternatives to reduce the prevalence of chronic wound infection associated with microbial biofilm. A novel approach to address these concerns is to inhibit biofilm formation using biological-macromolecule based nano-delivery system. Higher drug loading efficiency, sustained drug release, enhanced drug stability, and improved bioavailability are advantages of employing nano-drug delivery systems to prevent microbial colonization and biofilm formation in chronic wounds. This review covers the pathogenesis, microbial biofilm formation, and immune response to chronic wounds. Furthermore, we also focus on macromolecule-based nanoparticles as wound healing therapies to reduce the increased mortality associated with chronic wound infections.

Skin Inflammation with a Focus on Wound Healing

Significance: The skin is the crucial first-line barrier against foreign pathogens. Compromise of this barrier presents in the context of inflammatory skin conditions and in chronic wounds. Skin conditions arising from dysfunctional inflammatory pathways severely compromise the quality of life of patients and have a high economic impact on the U.S. health care system. The development of a thorough understanding of the mechanisms that can disrupt skin inflammation is imperative to successfully modulate this inflammation with therapies. Recent Advances: Many advances in the understanding of skin inflammation have occurred during the past decade, including the development of multiple new pharmaceuticals. Mechanical force application has been greatly advanced clinically. Bioscaffolds also promote healing, while reducing scarring. Critical Issues: Various skin inflammatory conditions provide a framework for analysis of our understanding of the phases of successful wound healing. The large burden of chronic wounds on our society continues to focus attention on the chronic inflammatory state induced in many of these skin conditions. Future Directions: Better preclinical models of disease states such as chronic wounds, coupled with enhanced diagnostic abilities of human skin, will allow a better understanding of the mechanism of action. This will lead to improved treatments with biologics and other modalities such as the strategic application of mechanical forces and scaffolds, which ultimately results in better outcomes for our patients.

Osteoimmunology in Periodontitis and Orthodontic Tooth Movement

PURPOSE OF REVIEW

To review the role of the immune cells and their interaction with cells found in gingiva, periodontal ligament, and bone that leads to net bone loss in periodontitis or bone remodeling in orthodontic tooth movement.

RECENT FINDINGS

Periodontal disease is one of the most common oral diseases causing inflammation in the soft and hard tissues of the periodontium and is initiated by bacteria that induce a host response. Although the innate and adaptive immune response function cooperatively to prevent bacterial dissemination, they also play a major role in gingival inflammation and destruction of the connective tissue, periodontal ligament, and alveolar bone characteristic of periodontitis. The inflammatory response is triggered by bacteria or their products that bind to pattern recognition receptors that induce transcription factor activity to stimulate cytokine and chemokine expression. Epithelial, fibroblast/stromal, and resident leukocytes play a key role in initiating the host response and contribute to periodontal disease. Single-cell RNA-seq (scRNA-seq) experiments have added new insight into the roles of various cell types in the response to bacterial challenge. This response is modified by systemic conditions such as diabetes and smoking. In contrast to periodontitis, orthodontic tooth movement (OTM) is a sterile inflammatory response induced by mechanical force. Orthodontic force application stimulates acute inflammatory responses in the periodontal ligament and alveolar bone stimulated by cytokines and chemokines that produce bone resorption on the compression side. On the tension side, orthodontic forces induce the production of osteogenic factors, stimulating new bone formation. A number of different cell types, cytokines, and signaling/pathways are involved in this complex process. Inflammatory and mechanical force-induced bone remodeling involves bone resorption and bone formation. The interaction of leukocytes with host stromal cells and osteoblastic cells plays a key role in both initiating the inflammatory events as well as inducing a cellular cascade that results in remodeling in orthodontic tooth movement or in tissue destruction in periodontitis.

The Potential of Topical Therapy for Diabetic Wounds: A Narrative Review

The rising prevalence of diabetes mellitus brings with it a rise in the occurrence of several complications of the disease such as chronic non-healing wounds. Diabetics are more prone to developing chronic wounds due to complications like peripheral neuropathy, poor foot care, hyperglycaemia and peripheral vascular diseases. The aim of this review is to discuss the various imbalances in the cytokine environment of diabetic wounds and to explore the developments in their management with an emphasis on agents that may be used topically to aid the healing process of chronic wounds. A systematic search was conducted on Scopus, PubMed and Google Scholar and relevant articles were shortlisted. We conclude that increased blood sugar impairs most phases of wound healing in several ways. Supplementary therapy with either topical or systemic cytokines is shown to promote wound healing in a diabetic wound.

Macrophages in Skin Wounds: Functions and Therapeutic Potential

Macrophages regulate cutaneous wound healing by immune surveillance, tissue repair and remodelling. The depletion of dermal macrophages during the early and middle stages of wound healing has a detrimental impact on wound closure, characterised by reduced vessel density, fibroblast and myofibroblast proliferation, delayed re-epithelization and abated post-healing fibrosis and scar formation. However, in some animal species, oral mucosa and foetal life, cutaneous wounds can heal normally and remain scarless without any involvement of macrophages. These paradoxical observations have created much controversy on macrophages' indispensable role in skin wound healing. Advanced knowledge gained by characterising macrophage subsets, their plasticity in switching phenotypes and molecular drivers provides new insights into their functional importance during cutaneous wound healing. In this review, we highlight the recent findings on skin macrophage subsets, their functional role in adult cutaneous wound healing and the potential benefits of targeting them for therapeutic use.

Impact of photobiomodulation on macrophages and their polarization during diabetic wound healing: a systematic review

This review aims to providing essential information and the current knowledge about the potential role of macrophages, especially their M2 subtypes in different diabetic wounds both in clinical and pre-clinical models under the influence of photobiomodulation (PBM). The long-term goal is to advance the macrophage-based therapies to accelerate healing of diabetic foot ulcers. We reviewed all databases provided by PubMed, Google Scholar, Scopus, Web of Science, and Cochrane precisely from their dates of inception to 25/10/2021. The keywords of Diabetes mellitus diseases, wound healing, macrophage, and photobiomodulation or low-level laser therapy were used in this systematic review.A total of 438 articles were initially identified in pubmed.ncbi.nlm.nih.gov (15 articles), Google scholar (398 articles), Scopus (18 articles), and Web of Science (7 articles). Four hundred sixteen articles that remained after duplicate studies (22 articles) were excluded. After screening abstracts and full texts, 14 articles were included in our analysis. Among them, 4 articles were about the effect of PBM on macrophages in type 2 diabetes and also found 10 articles about the impact of PBM on macrophages in type 1 diabetes. The obtained data from most of the reviewed studies affirmed that the PBM alone or combined with other agents (e.g., stem cells) could moderate the inflammatory response and accelerate the wound healing process in pre-clinical diabetic wound models. However, only very few studies conducted the detailed functions of polarized macrophages and M2 subtypes in wound healing of diabetic models under the influence of PBM. Further pre-clinical and clinical investigations are still needed to investigate the role of M2 macrophages, especially its M2c subtype, in the healing processes of diabetic foot ulcers in clinical and preclinical settings.

Wound Healing Impairment in Type 2 Diabetes Model of Leptin-Deficient Mice—A Mechanistic Systematic Review

Type II diabetes mellitus (T2DM) is one of the most prevalent diseases in the world, associated with diabetic foot ulcers and impaired wound healing. There is an ongoing need for interventions effective in treating these two problems. Pre-clinical studies in this field rely on adequate animal models. However, producing such a model is near-impossible given the complex and multifactorial pathogenesis of T2DM. A leptin-deficient murine model was developed in 1959 and relies on either dysfunctional leptin (ob/ob) or a leptin receptor (db/db). Though monogenic, this model has been used in hundreds of studies, including diabetic wound healing research. In this study, we systematically summarize data from over one hundred studies, which described the mechanisms underlying wound healing impairment in this model. We briefly review the wound healing dynamics, growth factors’ dysregulation, angiogenesis, inflammation, the function of leptin and insulin, the role of advanced glycation end-products, extracellular matrix abnormalities, stem cells’ dysregulation, and the role of non-coding RNAs. Some studies investigated novel chronic diabetes wound models, based on a leptin-deficient murine model, which was also described. We also discussed the interventions studied in vivo, which passed into human clinical trials. It is our hope that this review will help plan future research.

Novel Insight into the Mechanisms of the Bidirectional Relationship between Diabetes and Periodontitis

Periodontitis and diabetes are two major global health problems despite their prevalence being significantly underreported and underestimated. Both epidemiological and intervention studies show a bidirectional relationship between periodontitis and diabetes. The hypothesis of a potential causal link between the two diseases is corroborated by recent studies in experimental animals that identified mechanisms whereby periodontitis and diabetes can adversely affect each other. Herein, we will review clinical data on the existence of a two-way relationship between periodontitis and diabetes and discuss possible mechanistic interactions in both directions, focusing in particular on new data highlighting the importance of the host response. Moreover, we will address the hypothesis that trained immunity may represent the unifying mechanism explaining the intertwined association between diabetes and periodontitis. Achieving a better mechanistic insight on clustering of infectious, inflammatory, and metabolic diseases may provide new therapeutic options to reduce the risk of diabetes and diabetes-associated comorbidities.

Qingwei San treats oral ulcer subjected to stomach heat syndrome in db/db mice by targeting TLR4/MyD88/NF-κB pathway

Background

Qingwei San (QWS), one of classic Chinese Medicine prescripts, has been widely used to treat stomach heat syndrome which manifests oral ulcer (OU), periodontitis and upper gastrointestinal bleeding for seven hundred years. However, the therapeutic effects of QWS on diabetic OU subjected to stomach heat syndrome are still ambiguous. In the study, we investigated the pharmacological mechanisms.

Methods

The main components of QWS aqueous extract were analyzed by LC–MS, and potential pathways of QWS targeting OU were predicted by network pharmacology. The db/db mice were administered with the decoction of dried Zingiber officinale Rosc. rhizome combined with NaOH cauterization to establish the model of diabetic OU subjected to stomach heat syndrome. Subsequently, the model mice were treated with QWS, and OU wound healing status were recorded. The pathological changes of gastric tissue and oral mucosa were evaluated using hematoxylin–eosin staining, and the morphology of collagen fibers in oral mucosa was assessed by Masson staining. The levels of thromboxane B₂ (TXB₂), 6-Keto-prostaglandin F1α (6-keto-PGF1α), interleukin-1 β (IL-1β), IL-2, IL-6, tumor necrosis factor-α (TNF-α), β-endorphin (β-EP) and 5-Hydroxytryptamine (5-HT) were determined by ELISA assay. The protein expressions of Toll-like receptor 4 (TLR4), TNF receptor associated factor 6 (TRAF6), myeloid differentiation factor 88 (MyD88), inhibitor of NF-κB alpha (IκΒα), p-IκΒα and nuclear factor kappa-B (NF-κB) p65 were measured by Western Blotting.

Results

A total of 183 compounds in QWS were identified by LC–MS, and identified 79 bioactive compounds corresponded to 269 targets and 59 pathways. QWS high-dose treatment significantly reduced the level of TXB₂ and the ratio of TXB₂/6-keto-PGF1α. Meanwhile, it improved mucosal pathological morphology, and reduced the area of OU and local edema. Simultaneously, the levels of TNF-α, IL-1β, IL-6, IL-2 and 5-HT, and the expressions of TLR4, TRAF6, MyD88, p-IκΒα and NF-κB p65 were decreased.

Conclusion

QWS treatment facilitates the healing of OU, ameliorates pathological morphologies of gastric and oral mucosa and decreases the levels of pro-inflammatory cytokines in db/db mice subjected to stomach heat syndrome, whose mechanism may be associated with the inhibition of TLR4/MyD88/NF-κB signaling pathway to exert anti-inflammatory effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00565-5.

Synergistic Effect of Biphasic Calcium Phosphate and Platelet-Rich Fibrin Attenuate Markers for Inflammation and Osteoclast Differentiation by Suppressing NF-κB/MAPK Signaling Pathway in Chronic Periodontitis

Background: Periodontitis is characterized by excessive osteoclastic activity, which is closely associated with inflammation. It is well established that MAPK/NF-kB axis is a key signaling pathway engaged in osteoclast differentiation. It is stated that that biphasic calcium phosphate (BCP) and platelet-rich fibrin (PRF) have significant antiostoeclastogenic effects in chronic periodontitis. Objective: We aimed to elucidate the synergetic effect of PRF/BCP involvement of the nuclear factor kappa–light–chain–enhancer of activated B cells (NF-kB) and the mitogen-activated protein kinase (MAPK) signaling pathway in osteoclast differentiation in chronic periodontitis. Methods: We induced osteoclast differentiation in vitro using peripheral blood mononuclear cells (PBMCs) derived from patients with chronic periodontitis. We assessed osteoclast generation by tartrate-resistant acid phosphatase (TRAP) activity, proinflammatory cytokines were investigated by ELISA and NF-κB, and IKB by immunoblot, respectively. MAPK proteins and osteoclast transcription factors were studied by Western blot analysis and osteoclast transcriptional genes were assessed by RT-PCR. Results: The results showed that the potent inhibitory effect of PRF/BCP on osteoclastogenesis was evidenced by decreased TRAP activity and the expression of transcription factors, NFATc1, c-Fos, and the osteoclast marker genes, TRAP, MMP-9, and cathepsin-K were found to be reduced. Further, the protective effect of PRF/BCP on inflammation-mediated osteoclastogenesis in chronic periodontitis was shown by decreased levels of proinflammatory cytokines, NF-kB, IKB, and MAPK proteins. Conclusions: PRF/BCP may promote a synergetic combination that could be used as a strong inhibitor of inflammation-induced osteoclastogenesis in chronic periodontitis.

Selective Antimicrobial Therapies for Periodontitis: Win the "Battle and the War"

Traditional antimicrobial therapies for periodontitis (PD) have long focused on non-selective and direct approaches. Professional cleaning of the subgingival biofilm by instrumentation of dental root surfaces, known as scaling and root planning (SRP), is the mainstay of periodontal therapy and is indisputably effective. Non-physical approaches used as adjuncts to SRP, such as chemical and biological agents, will be the focus of this review. In this regard, traditional agents such as oral antiseptics and antibiotics, delivered either locally or systemically, were briefly reviewed as a backdrop. While generally effective in winning the “battle” against PD in the short term, by reducing its signs and symptoms, patients receiving such therapies are more susceptible to recurrence of PD. Moreover, the long-term consequences of such therapies are still in question. In particular, concern about chronic use of systemic antibiotics and their influence on the oral and gut microbiota is warranted, considering antibiotic resistance plasmids, and potential transfer between oral and non-oral microbes. In the interest of winning the “battle and the war”, new more selective and targeted antimicrobials and biologics for PD are being studied. These are principally indirect, blocking pathways involved in bacterial colonization, nutrient acquisition, inflammation or cellular invasion without directly killing the pathogens. This review will focus on current and prospective antimicrobial therapies for PD, emphasizing therapies that act indirectly on the microbiota, with clearly defined cellular and molecular targets.

Abnormal macrophage polarization impedes the healing of diabetes-associated tooth sockets

Patients with poorly controlled type 2 diabetes mellitus (T2DM) often experience delayed tooth extraction socket (TES) healing. Delayed healing is often associated with an aberrant inflammatory response orchestrated by either M1 pro-inflammatory or M2 anti-inflammatory macrophages. However, the precise mechanism for the attenuated TES healing remains unclear. Here we used diet-induced T2DM mice as a model to study TES. Compared with the control group, the T2DM group showed delayed TES healing and diminished expression of osteogenic and angiogenic genetic profiles. Meanwhile, we detected a more inflammatory profile, with more M1 macrophages and TNF-α expression and less M2 macrophages and PPARγ expression, in TES in the T2DM group when compared to control mice. In vitro co-culture models showed that M1 macrophages inhibited the osteogenic capacity of bone marrow stromal cells and the angiogenic capacity of endothelial cells while M2 macrophages showed an opposite effect. In addition, we constructed a gelatin/β-TCP scaffold with IL-4 to induce macrophage transformation towards M2 polarization. In vitro analyses of the hybrid scaffold revealed sustained release of IL-4 and a phenotype switch to M2 macrophages. Finally, we demonstrated that sustained IL-4 release significantly increased expression of osteogenic and angiogenic genetic profiles and improved TES healing in T2DM mice. Together, we report that increased M1 and decreased M2 macrophage polarization may be responsible for delayed TES healing in T2DM patients through abnormal expression of TNF-α and PPARγ. This imbalance negatively influences osteogenesis and angiogenesis, two of the most important biological factors in bone wound healing. Enhancing M2 macrophage polarization with IL-4 delivery system may represent a potential strategy for promoting the healing of TES in T2DM patients.

Low mortality oxidative stress murine chronic wound model

INTRODUCTION

Investigators have struggled to produce a reliable chronic wound model. Recent progress with antioxidant enzyme inhibitors shows promise, but mortality rates are high. We modified the dosage and administration of an antioxidant enzyme inhibitor regimen to reduce mortality while inducing a chronic wound environment.

RESEARCH DESIGN AND METHODS

To chemically induce a chronic wound environment, we applied modified doses of catalase (3-amino-1,2,4-triazole; intraperitoneal 0.5 g/kg) and glutathione peroxidase (mercaptosuccinic acid; topical 300 mg/kg) inhibitors to the dorsal wounds of 11-week-old db/db mice. A cohort of these mice was treated with a collagen-glycosaminoglycan scaffold. Both groups were compared with Diabetic control mice.

RESULTS

This study successfully induced a chronic wound in 11-week-old db/db mice, with no animal deaths. The antioxidant enzyme treated groups showed delayed wound contraction and significantly higher levels of inflammatory tissue, collagen deposition, cellular proliferation and leukocyte infiltration than the Diabetic control group. Angiogenesis was significantly higher in the antioxidant enzyme treated groups, but the vessels were immature and friable. Scaffold engraftment was poor but appeared to promote blood vessel maturation.

CONCLUSIONS

Overall, the two in vivo groups treated with the antioxidant enzyme inhibitors appeared to be arrested in the inflammatory stage of wound healing, while the Diabetic control group progressed to the maturation phase and ultimately remodeling. This model may be instrumental for the development of new wound therapeutics.

Nanoparticle-Based Therapeutic Approach for Diabetic Wound Healing

Diabetes mellitus (DM) is a common endocrine disease characterized by a state of hyperglycemia (higher level of glucose in the blood than usual). DM and its complications can lead to diabetic foot ulcer (DFU). DFU is associated with impaired wound healing, due to inappropriate cellular and cytokines response, infection, poor vascularization, and neuropathy. Effective therapeutic strategies for the management of impaired wound could be attained through a better insight of molecular mechanism and pathophysiology of diabetic wound healing. Nanotherapeutics-based agents engineered within 1-100 nm levels, which include nanoparticles and nanoscaffolds, are recent promising treatment strategies for accelerating diabetic wound healing. Nanoparticles are smaller in size and have high surface area to volume ratio that increases the likelihood of biological interaction and penetration at wound site. They are ideal for topical delivery of drugs in a sustained manner, eliciting cell-to-cell interactions, cell proliferation, vascularization, cell signaling, and elaboration of biomolecules necessary for effective wound healing. Furthermore, nanoparticles have the ability to deliver one or more therapeutic drug molecules, such as growth factors, nucleic acids, antibiotics, and antioxidants, which can be released in a sustained manner within the target tissue. This review focuses on recent approaches in the development of nanoparticle-based therapeutics for enhancing diabetic wound healing.

Mucosal Immunity and the FOXO1 Transcription Factors

FOXO1 transcription factors affect a number of cell types that are important in the host response. Cell types whose functions are modulated by FOXO1 include keratinocytes in the skin and mucosal dermis, neutrophils and macrophages, dendritic cells, Tregs and B-cells. FOXO1 is activated by bacterial or cytokine stimulation. Its translocation to the nucleus and binding to promoter regions of genes that have FOXO response elements is stimulated by the MAP kinase pathway and inhibited by the PI3 kinase/AKT pathway. Downstream gene targets of FOXO1 include pro-inflammatory signaling molecules (TLR2, TLR4, IL-1β, and TNF-α), wound healing factors (TGF-β, VEGF, and CTGF) adhesion molecules (integrins-β1, -β3, -β6, α_vβ₃, CD11b, CD18, and ICAM-1), chemokine receptors (CCR7 and CXCR2), B cell regulators (APRIL and BLYS), T-regulatory modulators (Foxp3 and CTLA-4), antioxidants (GPX-2 and cytoglobin), and DNA repair enzymes (GADD45α). Each of the above cell types are found in oral mucosa and modulated by bacteria or an inflammatory microenvironment. FOXO1 contributes to the regulation of these cells, which collectively maintain and repair the epithelial barrier, formation and activation of Tregs that are needed to resolve inflammation, mobilization, infiltration, and activation of anti-bacterial defenses in neutrophils, and the homing of dendritic cells to lymph nodes to induce T-cell and B-cell responses. The goal of the manuscript is to review how the transcription factor, FOXO1, contributes to the activation and regulation of key leukocytes needed to maintain homeostasis and respond to bacterial challenge in oral mucosal tissues. Examples are given with an emphasis on lineage specific deletion of Foxo1 to explore the impact of FOXO1 on cell behavior, inflammation and susceptibility to infection.

High glucose environment induces M1 macrophage polarization that impairs keratinocyte migration via TNF-α: An important mechanism to delay the diabetic wound healing

BACKGROUND

Macrophages play important roles during wound healing, and delayed healing in diabetics is associated with sustained inflammation. M1 type macrophage is recognized to secrete excessive amount of tumor necrosis factor-alpha (TNF-α) as compared to its M2 counterpart.

OBJECTIVES

We hypothesized that macrophage polarization is different between diabetic and normal rats during skin wounding and has direct impact on keratinocyte function in the context of re-epithelialization.

METHODS

Skin wounds were created in diabetic and control rats. The phenotypes of infiltrating macrophages, the levels of TNF-α, and the rate of wound closure were determined. Using cell model, the effects of M1 type macrophage on keratinocyte migration were evaluated, and the potential regulatory pathways were determined.

RESULTS

The percentage of M1 macrophages and the levels of TNF-α expression were significantly higher in the perilesional area of diabetic rats as compared to control. The condition media (CM) from M1 type macrophage upregulated tissue inhibitor metalloproteinases (TIMP)-1 expression in keratinocytes and significantly reduced keratinocyte migratory capacity. Addition of neutralizing TNF-α antibody to the CM or gene-silencing of TIMP1 in keratinocytes restored the keratinocyte migratory capacity. Treating wounds of diabetic rats with TNF-α antagonist improved the wound healing process.

CONCLUSIONS

In summary, high glucose wound environment harbored more M1 macrophages infiltration, an event that created excess TNF-α micro-environment. TNF-α upregulated TIMP1 expression in keratinocytes and resulted in impaired keratinocyte migration. Taken together, these events contributed to impaired wound healing during diabetic condition, and targeting TNF-α is a potential therapeutic option to improve diabetic wound healing.

Lipid nanoparticles silence tumor necrosis factor α to improve wound healing in diabetic mice

Diabetes mellitus is a mounting concern in the United States, as are the mortality and morbidity that result from its complications. Of particular concern, diabetes patients frequently suffer from impaired wound healing and resultant nonhealing diabetic foot ulcers. These ulcers overproduce tumor necrosis factor α (TNFα), which reduces wound bed cell migration and proliferation while encouraging apoptosis. Herein, we describe the use of siRNA-loaded lipid nanoparticles (LNPs) as a potential wound treatment to combat an overzealous immune response and facilitate wound closure. LNPs were formulated with an ionizable, degradable lipidoid and siRNA specific for TNFα. Topical application of nanoparticles reduced TNFα mRNA expression in the wound by 40-55% in diabetic and nondiabetic mice. In diabetic mice, this TNFα knockdown accelerated wound healing compared to untreated controls. Together, these results serve as proof-of-concept that RNA interference therapy using LNPs can reduce the severity and duration of chronic diabetic wounds.

Toll-like receptor 4 attenuates a murine model of atopic dermatitis through inhibition of langerin-positive DCs migration

Atopic dermatitis (AD) is a common chronic inflammatory skin disease that is often associated with skin barrier dysfunction leading to a higher frequency of bacterial and viral skin infections. Toll-like receptor (TLR) 4 on resident skin cells was involved in sensing pathogens and eliciting pathogen-specific innate and adaptive immune responses. Previous studies have demonstrated that TLR4 was linked to AD severity in context of pathogen infection. However, the immune regulatory role of TLR4 in AD remains to be defined. We here investigated the immune regulatory function of TLR4 in AD induced by repeated epicutaneous application of a hapten, 2,4-dinitrochlorobenzene (DNCB). Our results showed that TLR4-deficient (TLR4^-/- ) mice exhibited more severe AD symptoms than WT mice after DNCB challenge. The DNCB-treated TLR4^-/- mice also displayed higher expression levels of inflammatory cytokines and stronger Th2 response than WT counterparts. Moreover, the skin expression of thymic stromal lymphopoietin (TSLP), an important potential contributor to allergic inflammation, was significantly elevated in TLR4^-/- mice compared with that in WT mice upon DNCB administration. Furthermore, we demonstrated that the migration of langerin-positive dendritic cells (DCs) into draining lymph nodes was enhanced in TLR4^-/- mice following DNCB challenge, which is partially dependent on the production of pro-inflammatory cytokine TNF-α. Together, these results determined that TLR4 affected the hapten-induced skin inflammation in the absence of exogenous pathogen infection, suggesting that TLR4 not only regulates infection but also may serve as a modulator of the immune response during AD development.

TNFα and Radioresistant Stromal Cells Are Essential for Therapeutic Efficacy of Cyclic Dinucleotide STING Agonists in Nonimmunogenic Tumors

The cGAS-STING cytosolic DNA sensing pathway may play an integral role in the initiation of antitumor immune responses. Studies evaluating the immunogenicity of various cyclic dinucleotide (CDN) STING agonists administered by intratumoral (i.t.) injection showed potent induction of inflammation, tumor necrosis, and, in some cases, durable tumor-specific adaptive immunity. However, the specific immune mechanisms underlying these responses remain incompletely defined. The majority of these studies have focused on the effect of CDNs on immune cells but have not conclusively interrogated the role of stromal cells in the acute rejection of the CDN-injected tumor. Here, we revealed a mechanism of STING agonist-mediated tumor response that relied on both stromal and immune cells to achieve tumor regression and clearance. Using knockout and bone marrow chimeric mice, we showed that although bone marrow-derived TNFα was necessary for CDN-induced necrosis, STING signaling in radioresistant stromal cells was also essential for CDN-mediated tumor rejection. These results provide evidence for crosstalk between stromal and hematopoietic cells during CDN-mediated tumor collapse after i.t. administration. These mechanistic insights may prove critical in the clinical development of STING agonists. Cancer Immunol Res; 6(4); 422-33. ©2018 AACR.

Healing of soft tissue lacerations in diabetic-induced rats

BACKGROUND/AIM

Prevalence and incidence of diabetes are increasing and many dental trauma patients today have diabetes. The implications of delayed wound healing, associated with diabetes mellitus, on oral mucosal wound healing have not been investigated extensively. The aim of this study was to investigate the implications of diabetes mellitus on the cellular, vascular, and fibroblastic changes induced by laceration on the oral mucosa of Wistar rats.

MATERIALS AND METHODS

Sixteen female Wistar rats were randomly assigned into two groups: 1. Experimental Streptozotocin-induced diabetic group (8 rats). 2. Control group (8 rats). A standardized laceration injury was induced from the corner of the mouth to the mid-check penetrating through dermal and oral mucosal contaminated by saliva. Samples were taken from the rats after sacrificing them on days 1,3,7, and 10. Inflammation was evaluated both qualitatively and quantitatively. Two investigators evaluated samples in a blinded manner.

RESULTS

Histology reports indicated delayed wound healing patterns in diabetic rats through days 1, 3, 7, and 10 when compared to controls. Inflammation was also noted to be consistently present more often in diabetic rats. Furthermore, polymorphonuclear cell count was consistently higher in diabetic rats.

CONCLUSION

The results suggest that oral mucosa wound healing is delayed in diabetic Wistar rats compared to non-diabetic rats in terms of wound closure, angiogenesis, and polymorphonuclear cells number. Furthermore, it is also suggested that wound healing is impaired both in the early and late stages of soft tissue wound healing.

Recent advances in biomaterials for the treatment of diabetic foot ulcers

Diabetes mellitus is one of the most challenging epidemics facing the world today, with over 300 million patients affected worldwide. A significant complication associated with diabetes is hyperglycemia, which impairs wound healing. The rise in the diabetic patient population in recent years has precipitated an increase in the incidence and prevalence of chronic diabetic wounds, most commonly the diabetic foot ulcer. Although foot ulcers are difficult to treat due to their complicated pathology, outcomes have improved with the development of increasingly sophisticated biomaterials that accelerate healing. In this review, we describe recently developed biomaterials that elicit healing through cell-material interactions and/or the sustained delivery of drugs. These tunable therapeutic systems increase angiogenesis, collagen deposition, cell proliferation, and growth factors concentrations, while decreasing inflammation and enzymatic degradation of the extracellular matrix. As the field of biomaterials for wound healing continues to mature, we expect to witness a broader range of clinical options that will speed healing times and improve patient quality of life.

Aged blood factors decrease cellular responses associated with delayed gingival wound repair

Aging is a gradual biological process characterized by a decrease in cell and organism functions. Gingival wound healing is one of the impaired processes found in old rats. Here, we studied the in vivo wound healing process using a gingival repair rat model and an in vitro model using human gingival fibroblast for cellular responses associated to wound healing. To do that, we evaluated cell proliferation of both epithelial and connective tissue cells in gingival wounds and found decreased of Ki67 nuclear staining in old rats when compared to their young counterparts. We next evaluated cellular responses of primary gingival fibroblast obtained from young subjects in the presence human blood serum of individuals of different ages. Eighteen to sixty five years old masculine donors were classified into 3 groups: “young” from 18 to 22 years old, “middle-aged” from 30 to 48 years old and “aged” over 50 years old. Cell proliferation, measured through immunofluorescence for Ki67 and flow cytometry for DNA content, was decreased when middle-aged and aged serum was added to gingival fibroblast compared to young serum. Myofibroblastic differentiation, measured through alpha-smooth muscle actin (α-SMA), was stimulated with young but not middle-aged or aged serum both the protein levels and incorporation of α-SMA into actin stress fibers. High levels of PDGF, VEGF, IL-6R were detected in blood serum from young subjects when compared to middle-aged and aged donors. In addition, the pro-inflammatory cytokines MCP-1 and TNF were increased in the serum of aged donors. In old rat wound there is an increased of staining for TNF compared to young wound. Moreover, healthy gingiva (non injury) shows less staining compared to a wound site, suggesting a role in wound healing. Moreover, serum from middle-aged and aged donors was able to stimulate cellular senescence in young cells as determined by the expression of senescence associated beta-galactosidase and histone H2A.X phosphorylated at Ser139. Moreover, we detected an increased frequency of γ-H2A.X-positive cells in aged rat gingival tissues. The present study suggests that serum factors present in middle-aged and aged individuals may be responsible, at least in part, for the altered responses observed during wound healing in aging.

Therapy with CTLA4-Ig and an antiviral monoclonal antibody controls chikungunya virus arthritis

In 2013, chikungunya virus (CHIKV) transmission was documented in the Western Hemisphere, and the virus has since spread throughout the Americas with more than 1.8 million people infected in more than 40 countries. CHIKV targets the joints, resulting in symmetric polyarthritis that clinically mimics rheumatoid arthritis and can endure for months to years. At present, no approved treatment is effective in preventing or controlling CHIKV infection or disease. We treated mice with eight different disease-modifying antirheumatic drugs and identified CLTA4-Ig (abatacept) and tofacitinib as candidate therapies based on their ability to decrease acute joint swelling. CTLA4-Ig reduced T cell accumulation in the joints of infected animals without affecting viral infection. Whereas monotherapy with CTLA4-Ig or a neutralizing anti-CHIKV human monoclonal antibody provided partial clinical improvement, therapy with both abolished swelling and markedly reduced levels of chemokines, proinflammatory cytokines, and infiltrating leukocytes. Thus, combination CTLA4-Ig and antiviral antibody therapy controls acute CHIKV infection and arthritis and may be a candidate for testing in humans.

Contribution of biomechanical forces to inflammation-induced bone resorption

AIM

This study aimed to evaluate the contribution of biomechanical loading to inflammation-induced tissue destruction.

MATERIALS AND METHODS

A total of 144 adult Holtzman rats were randomly assigned into four experimental groups: control (C), ligature-induced periodontal disease (P), orthodontic movement (OM), and combination group (OMP). On days 1, 3, 7, and 15, following baseline, nine animals from each experimental group were killed. Bone volume fraction (BVF) and bone mineral density (BMD) were measured using micro-computed tomography. Expression and synthesis profile of cytokines and receptors of inflammation in gingival tissues were evaluated by PCR array assay and multiplex immunoassay.

RESULTS

At 15 days, the OMP group presented a significantly (p < 0.05) lower BVF and BMD levels when compared to all the other groups. The OMP group presented the highest number of upregulated protein targets in comparison to the other groups. Furthermore, the gene expression and protein levels of CCL2, CCL3, IL-1β, IL1-α, IL-18, TNF-α, and VEGF were significantly (p < 0.05) higher in the OMP group when compared to the P group.

CONCLUSIONS

In summary, mechanical loading modulates the inflammatory response of periodontal tissues to periodontal disease by increasing the expression of several pro-inflammatory mediators and receptors, which leads to increased bone resorption.

Effect of the herbal mixture composed of Aloe Vera, Henna, Adiantum capillus-veneris, and Myrrha on wound healing in streptozotocin-induced diabetic rats

BACKGROUND

Wound healing is often impaired in diabetic animals and humans. Matrix metalloproteases act as pro-inflammatory agents in physiological wound healing pathways by stimulating cytokines including the interleukins, IL6, IL1A and IL1B, and the tumor necrosis factor and transforming growth factor beta1. Botanicals are traditionally used to assist healing of different types of wounds, because they produce fewer side effects. Our specific aim here was to develop a plant-based recipe supporting effective wound healing in diabetic animals.

METHODS

Plant materials from Adiantum capillus-veneris, Commiphora molmol, Aloe Vera, and henna were collected for this study, and oven-dried at 60 °C. The dried leaves and resins were then crumbled into a powder and mixed in equal parts with Vaseline as a preservative. This mixture was used as an ointment on wounds induced in 60 diabetic and non-diabetic rats that were divided into 6 subgroups receiving agent or control treatments. Necrotic tissue surrounding the wound was periodically removed during wound healing. RNA was extracted from the healing region of the wound at days 7, 14 and 21 for cDNA synthesis to monitor changes in Tgfb1, Mmp3, Mmp9, Il6 and Tnf α expression using real-time PCR.

RESULTS

The expression of the Mmp3, the Tnf α, and the Tgfb1 genes from wound tissue were significantly different (p < 0.05) between diabetic and non-diabetic (control) rats treated with the herbal mixture after 14 and 21 days. There was no significant difference (p > 0.05) of the Mmp9 gene expression in diabetic and non-diabetic rats treated only with Vaseline after 7, 14, and 21 days. But, the expression of the Mmp9 gene decreased significantly (p < 0.05) in diabetic rats after 14 days in comparison to non-diabetic rats, when the herbal mixture was added to Vaseline.

CONCLUSIONS

Our study presents an herbal treatment that alters the gene expression signature at wounds induced in the rat model for type I diabetes in a manner consistent with accelerated healing, and demonstrates that this herbal treatment might be effective to treat wounds in diabetic patients.

DNA Demethylation Rescues the Impaired Osteogenic Differentiation Ability of Human Periodontal Ligament Stem Cells in High Glucose

Diabetes mellitus, characterized by abnormally high blood glucose levels, gives rise to impaired bone remodeling. In response to high glucose (HG), the attenuated osteogenic differentiation capacity of human periodontal ligament stem cells (hPDLSCs) is associated with the loss of alveolar bone. Recently, DNA methylation was reported to affect osteogenic differentiation of stem cells in pathological states. However, the intrinsic mechanism linking DNA methylation to osteogenic differentiation ability in the presence of HG is still unclear. In this study, we found that diabetic rats with increased DNA methylation levels in periodontal ligaments exhibited reduced bone mass and density. In vitro application of 5-aza-2′-deoxycytidine (5-aza-dC), a DNA methyltransferase inhibitor, to decrease DNA methylation levels in hPDLSCs, rescued the osteogenic differentiation capacity of hPDLSCs under HG conditions. Moreover, we demonstrated that the canonical Wnt signaling pathway was activated during this process and, under HG circumstances, the 5-aza-dC-rescued osteogenic differentiation capacity was blocked by Dickkopf-1, an effective antagonist of the canonical Wnt signaling pathway. Taken together, these results demonstrate for the first time that suppression of DNA methylation is able to facilitate the osteogenic differentiation capacity of hPDLSCs exposed to HG, through activation of the canonical Wnt signaling pathway.

TNF-alpha expression, evaluation of collagen, and TUNEL of Matricaria recutita L. extract and triamcinolone on oral ulcer in diabetic rats

OBJECTIVE

to evaluate the influence of Tumor Necrosis Factor alpha (TNF-α) and apoptosis in rats with DM treated with chamomile extract or triamcinolone.

MATERIAL AND METHODS

Wistar male rats (210.0±4.2 g) were divided into five groups: negative control group (NCG) without diabetes; positive control group (PCG) with DM (alloxan, 45 mg/kg); and groups treated with chamomile extract (normoglycemic= NCG group and diabetic= DCG group) and with triamcinolone (TG). Traumatic ulcers were performed on all animals that received topical triamcinolone, chamomile extract or saline 12/12 hours for ten days.

RESULTS

On days five and ten the animals were euthanized and the ulcers were analyzed by light microscopy, TUNEL assay, and immunohistochemically (TNF-α). The NCG (p=0.0062), PCG (p=0.0285), NCG (p=0.0041), and DCG (p<0.0001) groups were completely healed on the 10th day, however, there was no healing on the TG (p=0.5127) group. The TNF-α expression showed a significant reduction from the 5th to the 10th day in NCG (p=0.0266) and DCG (p=0.0062). In connective tissue, the TUNEL assay showed a significant reduction in the number of positive cells in NCG (p=0.0273) and CNG (p=0.0469) and in the epithelium only in CDG (p=0.0320).

CONCLUSIONS

Chamomile extract can optimize the healing of traumatic oral ulcers in diabetic rats through the reduction of apoptosis in the epithelium and TNF-α expression.

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.

TNF-α is upregulated in T2DM patients with fracture and promotes the apoptosis of osteoblast cells in vitro in the presence of high glucose

Fracture healing is regulated by proinflammatory mediators such as tumor necrosis factor-α (TNF-α), which poses influence on the balance between bone formation and remodeling. And the diabetes is thought to contribute to the delayed diabetic fracture healing. In the present study, we examined the promotion to proinflammatory cytokines and chemokines in type 2 diabetes mellitus (T2DM) patients with bone fractures, and then evaluated the promotion to TNF-α by the high glucose treatment in human osteoblast-like MG-63 cells and the regulatory role of the promoted TNF-α on the MG-63 cell apoptosis. It was demonstrated that there were significantly-upregulated high-sensitivity C-reactive protein (hsCRP) TNF-α, IL-1β, IL-6, IFN-γ-inducible protein 10 (IP-10) and RANTES in T2DM patients with bone fracture. And the promotion to TNF-α and IL-1β was confirmed in vitro in both mRNA and protein levels in high glucose-treated MG-63 cells. And either TNF-α or high glucose reduced the viability of MG-63 cells, promoted apoptosis and upregulated apoptosis-associated markers, such as released cytochrome c, cleaved caspase 3 and lyzed PARP. Moreover, there was a synergistic effect between TNF-α and high glucose. The viability reduction and the apoptosis induction of MG-63 cells were significantly higher in the group with both TNF-α and high glucose treatments, than in the group with singular TNF-α treatment. In conclusion, our study demonstrated that proinflammatory cytokines and chemokines were promoted in T2DM patients with bone fracture or in osteoblasts by the high glucose stimulation. TNF-α and high glucose synergistically reduced the viability and induced the apoptosis in the osteoblast-like MG-63 cells in vitro. It implies the significant regulatory role of TNF-α in the delayed fracture healing in T2DM.

Silencing TNFα with lipidoid nanoparticles downregulates both TNFα and MCP-1 in an in vitro co-culture model of diabetic foot ulcers

Diabetes is one of the most formidable diseases facing the world today, with the number of patients growing every year. Poor glycemic control yields a host of complications, such as impaired wound healing. This often results in the formation of diabetic foot ulcers, which carry a poor prognosis because they are notoriously difficult to treat. Current therapies do not address the increased number of infiltrating macrophages to the wound bed that overproduce tumor necrosis factor α (TNFα), which increases fibroblast apoptosis and collagen dismantling and decreases angiogenesis. In this study, we investigated the potential of RNA interference therapy to reduce the inappropriately high levels of TNFα in the wound bed. Although TNFα is a challenging gene silencing target, our lipidoid nanoparticles potently silence TNFα mRNA and protein expression at siRNA doses of 5-100nM without inducing vehicle-related gene silencing or cell death. We also describe the creation of an in vitro macrophage-fibroblast co-culture model, which reflects the TNFα and monocyte chemotactant protein-1 (MCP-1/CCL2) cross-talk that exists in diabetic wounds. Because TNFα induces fibroblasts to produce MCP-1, we show that silencing TNFα results in a downregulation of MCP-1, which should inhibit the recruitment of additional macrophages to the wound. In co-culture experiments, a single lipidoid nanoparticle dose of 100nM siTNFα downregulated TNFα and MCP-1 by 64% and 32%, respectively. These data underscore the potential of lipidoid nanoparticle RNAi treatment to inhibit a positive feedback cycle that fuels the pathogenesis of diabetic foot ulcers.

STATEMENT OF SIGNIFICANCE

Diabetic foot ulcers are a rapidly growing issue worldwide, with current ulcer treatments not as effective as desired. RNA interference therapy represents a largely untapped possible solution to impaired wound healing. We show that siRNA-loaded lipidoid nanoparticles silence the overexpression of tumor necrosis factor α (TNFα) in inflammatory macrophages which leads to a subsequent downregulation of fibroblast-produced macrophage chemotactant protein-1 (MCP-1). Both TNFα and MCP-1 are critical components of the inflammatory feedback loop that exists in chronic wounds. In contrast to the majority of wound drug delivery studies, our study utilizes macrophage/fibroblast co-culture experiments to recapitulate a multicellular wound environment in which cytokine signaling influences inflammation. Results underscore the therapeutic potential of siRNA nanoparticles directed against TNFα in inhibiting two key inflammatory targets in chronic wounds.

The enduring importance of animal models in understanding periodontal disease

Whereas no single animal model can reproduce the complexity of periodontitis, different aspects of the disease can be addressed by distinct models. Despite their limitations, animal models are essential for testing the biological significance of in vitro findings and for establishing cause-and-effect relationships relevant to clinical observations, which are typically correlative. We provide evidence that animal-based studies have generated a durable framework for dissecting the mechanistic basis of periodontitis. These studies have solidified the etiologic role of bacteria in initiating the inflammatory response that leads to periodontal bone loss and have identified key mediators (IL-1, TNF, prostaglandins, complement, RANKL) that induce inflammatory breakdown. Moreover, animal studies suggest that dysbiosis, rather than individual bacterial species, are important in initiating periodontal bone loss and have introduced the concept that organisms previously considered commensals can play important roles as accessory pathogens or pathobionts. These studies have also provided insight as to how systemic conditions, such as diabetes or leukocyte adhesion deficiency, contribute to tissue destruction. In addition, animal studies have identified and been useful in testing therapeutic targets.

Cytosine-Phosphorothionate-Guanine Oligodeoxynucleotides Exacerbates Hemophagocytosis by Inducing Tumor Necrosis Factor-Alpha Production in Mice after Bone Marrow Transplantation

Hemophagocytic syndrome (HPS) is frequently associated with hematopoietic stem cell transplantation and is treated with some benefit derived from TNF-α inhibitors. However, the mechanisms of how HPS occurs and how a TNF-α inhibitor exerts some benefit to HPS management have remained unclear. We evaluated the effect of toll-like receptor (TLR) ligands, especially focusing on cytosine-phosphorothionate-guanine oligodeoxynucleotide (CpG), a TLR9 ligand, on HPS in mice that underwent transplantation with syngeneic or allogeneic bone marrow (BM) cells (Syn-BMT, Allo-BMT), or with allogeneic BM cells plus splenocytes to promote graft-versus-host disease (GVHD mice). Hemophagocytosis was a common feature early after all BMT, but it subsided in Syn-BMT and Allo-BMT mice. In GVHD mice, however, hemophagocytosis persisted and was accompanied by upregulated production of IFN-γ but not TNF-α, and it was suppressed by blockade of IFN-γ but not TNF-α. A single injection of the TLR9 ligand CpG promoted HPS in all BMT mice and was lethal in GVHD mice, accompanied by greatly upregulated production of TNF-α, IL-6, and IFN-γ. Blocking of TNF-α, but not IL-6 or IFN-γ, suppressed CpG-induced HPS in all BMT mice and rescued GVHD mice from CpG-induced mortality. Thus, TLR9 signaling mediates TNF-α-driven HPS in BMT mice and is effectively treated through TNF-α inhibition.

Loss of Bone and Wnt10b Expression in Male Type 1 Diabetic Mice Is Blocked by the Probiotic Lactobacillus reuteri

Type 1 diabetes (T1D)-induced osteoporosis is characterized by a predominant suppression of osteoblast number and activity, as well as increased bone marrow adiposity but no change in osteoclast activity. The fundamental mechanisms and alternative anabolic treatments (with few side effects) for T1D bone loss remain undetermined. Recent studies by our laboratory and others indicate that probiotics can benefit bone health. Here, we demonstrate that Lactobacillus reuteri, a probiotic with anti-inflammatory and bone health properties, prevents T1D-induced bone loss and marrow adiposity in mice. We further found that L. reuteri treatment prevented the suppression of Wnt10b in T1D bone. Consistent with a role for attenuated bone Wnt10b expression in T1D osteoporosis, we observed that bone-specific Wnt10b transgenic mice are protected from T1D bone loss. To examine the mechanisms of this protection, we focused on TNF-α, a cytokine up-regulated in T1D that causes suppression of osteoblast Wnt10b expression in vitro. Addition of L. reuteri prevented TNF-α-mediated suppression of Wnt10b and osteoblast maturation markers. Taken together, our findings reveal a mechanism by which T1D causes bone loss and open new avenues for use of probiotics to benefit the bone.

Diabetes mellitus related bone metabolism and periodontal disease

Diabetes mellitus and periodontal disease are chronic diseases affecting a large number of populations worldwide. Changed bone metabolism is one of the important long-term complications associated with diabetes mellitus. Alveolar bone loss is one of the main outcomes of periodontitis, and diabetes is among the primary risk factors for periodontal disease. In this review, we summarise the adverse effects of diabetes on the periodontium in periodontitis subjects, focusing on alveolar bone loss. Bone remodelling begins with osteoclasts resorbing bone, followed by new bone formation by osteoblasts in the resorption lacunae. Therefore, we discuss the potential mechanism of diabetes-enhanced bone loss in relation to osteoblasts and osteoclasts.

Glomerular cytokine expression in murine lupus nephritis

BACKGROUND

Aberrant expression of T helper cell (Th) cytokines is believed to play a central role in the pathogenesis of systemic lupus erythematosus (SLE). While the glomerulus is one of the major targets of lupus inflammation, little is known about the cytokine expression in glomeruli. The current study aimed to explore the profiles of Th cytokine gene expressions in isolated glomeruli of lupus-prone mice.

METHODS

Glomeruli were purified from lupus-prone MRL/lpr mice using the magnetic microbead method. Expressions of cytokine genes representing the Th subset and FoxP3 were examined using real-time polymerase chain reaction. Serum levels of these cytokines were also measured by enzyme-linked immunosorbent assay. MRL/n mice were used as controls. Histologic glomerular damages were scored semiquantitatively. To examine the role of TNF-α in glomerular damage, we administered etanercept, a TNF-α antagonist, into the subjects.

RESULTS

Glomerular gene expressions of TNF-α in lpr mice increased with week postpartum and reached statistically significant levels at 16 weeks compared with those of the glomeruli from control mice. Expressions of IFN-γ, IL-4 and FoxP3 also increased, but the difference was not significant. There was a significant increase in serum levels of TNF-α, IFN-γ, and IL-17 and decrease in those of IL-4. Among the genes examined, TNF-α significantly correlated with glomerular damage score. Administration of etanercept did not affect glomerular cytokine expressions or proteinuria and failed to ameliorate histologic glomerular damages.

CONCLUSION

Our data suggest that Th1 cytokines, especially TNF-α, are dominantly expressed in the glomeruli of lupus-prone mice, but its pathophysiological role remains unclear.

Diabetes reduces mesenchymal stem cells in fracture healing through a TNFα-mediated mechanism

AIMS/HYPOTHESIS

Diabetes interferes with bone formation and impairs fracture healing, an important complication in humans and animal models. The aim of this study was to examine the impact of diabetes on mesenchymal stem cells (MSCs) during fracture repair.

METHODS

Fracture of the long bones was induced in a streptozotocin-induced type 1 diabetic mouse model with or without insulin or a specific TNFα inhibitor, pegsunercept. MSCs were detected with cluster designation-271 (also known as p75 neurotrophin receptor) or stem cell antigen-1 (Sca-1) antibodies in areas of new endochondral bone formation in the calluses. MSC apoptosis was measured by TUNEL assay and proliferation was measured by Ki67 antibody. In vitro apoptosis and proliferation were examined in C3H10T1/2 and human-bone-marrow-derived MSCs following transfection with FOXO1 small interfering (si)RNA.

RESULTS

Diabetes significantly increased TNFα levels and reduced MSC numbers in new bone area. MSC numbers were restored to normal levels with insulin or pegsunercept treatment. Inhibition of TNFα significantly reduced MSC loss by increasing MSC proliferation and decreasing MSC apoptosis in diabetic animals, but had no effect on MSCs in normoglycaemic animals. In vitro experiments established that TNFα alone was sufficient to induce apoptosis and inhibit proliferation of MSCs. Furthermore, silencing forkhead box protein O1 (FOXO1) prevented TNFα-induced MSC apoptosis and reduced proliferation by regulating apoptotic and cell cycle genes.

CONCLUSIONS/INTERPRETATION

Diabetes-enhanced TNFα significantly reduced MSC numbers in new bone areas during fracture healing. Mechanistically, diabetes-enhanced TNFα reduced MSC proliferation and increased MSC apoptosis. Reducing the activity of TNFα in vivo may help to preserve endogenous MSCs and maximise regenerative potential in diabetic patients.

FOXO1, TGF-β regulation and wound healing

Re-epithelialization is a complex process that involves migration and proliferation of keratinocytes, in addition to the production of cytokines and growth factors that affect other cells. The induction of transcription factors during these processes is crucial for successful wound healing. The transcription factor forkhead boxO-1 (FOXO1) has recently been found to be an important regulator of wound healing. In particular, FOXO1 has significant effects through regulation of transforming growth factor-beta (TGF-β) expression and protecting keratinocytes from oxidative stress. In the absence of FOXO1, there is increased oxidative damage, reduced TGF-β1 expression, reduced migration and proliferation of keratinocytes and increased keratinocytes apoptosis leading to impaired re-epithelialization of wounds.

Periodontitis and type II diabetes: a two-way relationship

For many years an association between diabetes and periodontitis has been suspected. In more recent times this relationship has been suggested to be bidirectional with each condition being able to influence the other. In this review the two-way relationship between diabetes and periodontitis is considered. For this narrative review a very broad search strategy of the literature was developed using both EMBASE and MEDLINE (via PubMed) databases. The reference lists from the selected papers were also scanned, and this provided an additional source of papers for inclusion and further assessment. The data available suggest that diabetes is a risk as well as a modifying factor for periodontitis. Individuals with diabetes are more likely to have periodontitis and with increased severity when diabetes is uncontrolled/poorly controlled. Possible mechanisms of how diabetes affects periodontitis include adipokine-mediated inflammation, neutrophil dysfunction, uncoupling of bone and advanced glycation end-products-receptor for advanced glycation end-products interaction. Evidence is accruing to support how periodontitis can affect diabetes and complications associated with diabetes. There is some evidence demonstrating that periodontal therapy can result in a moderate improvement in glycaemic control. Available evidence indicates that diabetes and peridontitis are intricately interrelated and that each condition has the capacity to influence clinical features of each other.