Comparison of Keratinocyte Proliferation in Diabetic and Non-Diabetic Inflamed Gingiva

Immunomodulation of Skin Repair: Cell-Based Therapeutic Strategies for Skin Replacement (A Comprehensive Review)

The immune system has a crucial role in skin wound healing and the application of specific cell-laden immunomodulating biomaterials emerged as a possible treatment option to drive skin tissue regeneration. Cell-laden tissue-engineered skin substitutes have the ability to activate immune pathways, even in the absence of other immune-stimulating signals. In particular, mesenchymal stem cells with their immunomodulatory properties can create a specific immune microenvironment to reduce inflammation, scarring, and support skin regeneration. This review presents an overview of current wound care techniques including skin tissue engineering and biomaterials as a novel and promising approach. We highlight the plasticity and different roles of immune cells, in particular macrophages during various stages of skin wound healing. These aspects are pivotal to promote the regeneration of nonhealing wounds such as ulcers in diabetic patients. We believe that a better understanding of the intrinsic immunomodulatory features of stem cells in implantable skin substitutes will lead to new translational opportunities. This, in turn, will improve skin tissue engineering and regenerative medicine applications.

Epigenetic changes caused by diabetes and their potential role in the development of periodontitis

Aims/Introduction

Periodontal disease, a chronic inflammation induced by bacteria, is closely linked with diabetes mellitus. Many complications associated with diabetes are related to epigenetic changes. However, the exact epigenetic changes whereby diabetes affects periodontal disease remain largely unknown. Thus, we sought to investigate the role of diabetes‐dependent epigenetic changes of gingival tissue in the susceptibility to periodontal disease.

Materials and Methods

We studied the effect of streptozotocin‐induced diabetes in minipigs on gingival morphological and epigenetic tissue changes. Accordingly, we randomly divided six minipigs into two groups: streptozotocin‐induced diabetes group, n = 3; and non‐diabetes healthy control group, n = 3. After 85 days, all animals were killed, and gingival tissue was collected for histology, deoxyribonucleic acid methylation analysis and immunohistochemistry.

Results

A diabetes mellitus model was successfully created, as evidenced by significantly increased blood glucose levels, reduction of pancreatic insulin‐producing β‐cells and histopathological changes in the kidneys. The gingival tissues in the diabetes group presented acanthosis of both gingival squamous epithelium and sulcular/junctional epithelium, and a significant reduction in the number and length of rete pegs. Deoxyribonucleic acid methylation analysis showed a total of 1,163 affected genes, of which 599 and 564 were significantly hypermethylated and hypomethylated, respectively. Immunohistochemistry staining showed that the hypomethylated genes – tumor necrosis factor‐α and interleukin‐6 – were positively expressed under the junctional epithelium area in the diabetes group.

Conclusions

Diabetes mellitus induces morphological and epigenetic changes in periodontal tissue, which might contribute to the increased susceptibility of periodontal diseases in patients with diabetes.

The impact of diabetes on periodontal diseases

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

The potential and limitations of induced pluripotent stem cells to achieve wound healing

Wound healing is the physiologic response to a disruption in normal skin architecture and requires both spatial and temporal coordination of multiple cell types and cytokines. This complex process is prone to dysregulation secondary to local and systemic factors such as ischemia and diabetes that frequently lead to chronic wounds. Chronic wounds such as diabetic foot ulcers are epidemic with great cost to the healthcare system as they heal poorly and recur frequently, creating an urgent need for new and advanced therapies. Stem cell therapy is emerging as a potential treatment for chronic wounds, and adult-derived stem cells are currently employed in several commercially available products; however, stem cell therapy is limited by the need for invasive harvesting techniques, immunogenicity, and limited cell survival in vivo. Induced pluripotent stem cells (iPSC) are an exciting cell type with enhanced therapeutic and translational potential. iPSC are derived from adult cells by in vitro induction of pluripotency, obviating the ethical dilemmas surrounding the use of embryonic stem cells; they are harvested non-invasively and can be transplanted autologously, reducing immune rejection; and iPSC are the only cell type capable of being differentiated into all of the cell types in healthy skin. This review focuses on the use of iPSC in animal models of wound healing including limb ischemia, as well as their limitations and methods aimed at improving iPSC safety profile in an effort to hasten translation to human studies.

Immunoexpression of vascular endothelial growth factor and Ki-67 in human gingival samples: An observational study

Aim:

To evaluate immunohistochemically vascular endothelial growth factor (VEGF) and Ki-67 in human gingival samples and to compare these factors between healthy and diabetic patients.

Materials and Methods:

A total of 50 subjects were included in the study. They were categorized into three groups: Periodontally healthy group, periodontally diseased gingiva without any systemic disease group and periodontally diseased gingiva with controlled type II diabetes mellitus (DM) group. Gingival biopsies were performed and immunohistochemical analysis were done for VEGF and Ki-67 staining in gingival samples.

Results:

The present study found moderate intensity staining for VEGF in periodontitis group and periodontitis with controlled type II DM group and mild intensity staining for VEGF in periodontally healthy group. With regard to Ki-67, negative staining was observed in periodontally healthy group and mild staining in periodontitis group and periodontitis with controlled type II DM group.

Conclusion:

Further investigation needs to be conducted to identify how VEGF and Ki-67 are involved in the tissue inflammation associated processes and the relationship between VEGF and Ki-67 in progression of periodontitis.

Risk factors for oral postoperative infection in patients with diabetes

The prevalence of diabetes mellitus in the general population has been increasing sharply. Currently, much is feared but little is known about postoperative complications of oral surgery among persons with diabetes. Existing dental education and practice guidelines cite excess infectious risk among patients with diabetes; however, empiric evidence to support such concerns is lacking. In fact, dentists commonly prescribe antibiotics when dental surgical procedures involve bone. This practice may contribute to the rising problem of microbial resistance and may increase overall healthcare costs. The growing number of dental patients with diabetes warrants strengthening the evidence base to guide their dental care and prevent possible morbid complications.

The influence of type I diabetes mellitus in periodontal disease induced changes of the gingival epithelium and connective tissue

Periodontal disease constitutes the most frequent chronic diseases in human dentition. Bacterial plaque is the main etiologic agent, although it is the host immune response that causes periodontal tissue destruction. Diabetes is considered an important risk factor, not only for the onset but also for progression of the disease. The aim of this study was to analyze structural changes in the rat gingival epithelium and connective tissue in response to the experimental periodontal disease induced by the ligature technique, under the influence of diabetes. The results showed that experimental periodontal disease is characterized by marked inflammation, affecting both the epithelial and connective tissues, causing degeneration of the dermal papilla, increase in the number of inflammatory cells, destruction of reticulin fibers, and accumulation of dense collagen fibers (fibrosis). These changes were worsened by diabetes, apparently by hampering the inflammatory response and affecting tissue repair of the affected tissues.

Expression of matrix metalloproteinases, cytokines, and connexins in diabetic and nondiabetic human keratinocytes before and after transplantation into an ex vivo wound-healing model

OBJECTIVE

Wound healing is known to require a well-organized balance of numerous factors, e.g., cytokines, matrix metalloproteinases (MMPs), and their inhibitors, as well as direct cell-cell communication (connexins). Disruption of this balance may lead to the formation of chronic wounds such as diabetic foot ulcers. The transplantation of autologous keratinocytes is a promising therapy for diabetic foot ulcers; however, little is known about their characteristics on a molecular level. Therefore, we intended to characterize transplanted keratinocytes from diabetic and nondiabetic origin before and after transplantation.

RESEARCH DESIGN AND METHODS

We isolated human keratinocytes from diabetic and nondiabetic origins and transplanted them into an ex vivo wound healing model. To characterize the keratinocytes, we investigated mRNA expression of MMP-1, MMP-2, and MMP-9; tissue inhibitor of MMP (TIMP)-1 and TIMP-2; interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha; Cx26 (connexin 26) and Cx43; and, for connexins, immunolocalization.

RESULTS

We found no significantly increased expression of the molecules investigated in cultured keratinocytes from diabetic compared with nondiabetic origin, even though there were significant differences for MMP-2, IL-1beta, and TNF-alpha in skin biopsies. Expression of IL-1beta was significantly lower in keratinocytes from diabetic origin. In the course of wound healing, differences in the dynamics of expression of MMP-1, IL-1beta, and Cx43 were observed.

CONCLUSIONS

Our results suggest that keratinocytes from diabetic origin are as capable for transplantation into chronic wounds as keratinocytes from healthy origin at the starting point of therapy. However, differences in expression dynamics later on might reflect the systemic influence of diabetes resulting in a memory of the transplanted keratinocytes.

Upregulation of the Expression of Epidermal Growth Factor and Its Receptor in Gingiva Upon Cyclosporin A Treatment

BACKGROUND

To understand the roles of epidermal growth factor (EGF) and EGF receptor (EGF-R) in cyclosporin A (CsA)-induced gingival overgrowth, expression of EGF and EGF-R upon CsA treatment was examined in an oral epidermoid carcinoma cell line of humans (OECM-1) and in edentulous gingiva of rats.

METHODS

In vitro study: after CsA treatment, OECM-1 cells were harvested to evaluate their mRNA and protein expression of EGF and EGF-R with reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot, and immunocytochemistry (ICC). In vivo study: 3 weeks after extraction of all maxillary molars, 20 male Sprague-Dawley rats were assigned to a CsA group (30 mg/kg, fed daily) and a control group. Five rats per group were sacrificed at weeks 1 and 4. Edentulous ridge specimens were obtained for evaluating their mRNAs and protein expression with RT-PCR, real-time RT-PCR, and immunohistochemistry (IHC). In both in vitro and in vivo experiments, the proliferating potential of epithelial cells was examined by the presence of proliferating cell nuclear antigen (PCNA).

RESULTS

In vitro: dose-dependently increased mRNA expression of EGF and EGF-R in OECM-1 cells was noted after CsA treatment. Protein expressions of EGF and EGF-R were higher in OECM-1 with CsA treatment than without CsA. In vivo: higher mRNA and protein expressions of EGF and EGF-R were also observed in the gingival tissues of CsA-treated rats. In both in vitro and in vivo experiments, greater PCNA expression after CsA treatment was demonstrated.

CONCLUSIONS

Higher expression of EGF and EGF-R upon CsA therapy was observed in OECM-1 epithelial cells of humans and in edentulous gingiva of rats. We suggest that CsA could upregulate gene and protein expression of EGF and EGF-R, and the upregulation may play a role in gingival overgrowth.

Wound healing and its impairment in the diabetic foot

Optimum healing of a cutaneous wound requires a well-orchestrated integration of the complex biological and molecular events of cell migration and proliferation, and of extracellular matrix deposition and remodelling. Cellular responses to inflammatory mediators, growth factors, and cytokines, and to mechanical forces, must be appropriate and precise. However, this orderly progression of the healing process is impaired in chronic wounds, including those due to diabetes. Several pathogenic abnormalities, ranging from disease-specific intrinsic flaws in blood supply, angiogenesis, and matrix turnover to extrinsic factors due to infection and continued trauma, contribute to failure to heal. Yet, despite these obstacles, there is increasing cause for optimism in the treatment of diabetic and other chronic wounds. Enhanced understanding and correction of pathogenic factors, combined with stricter adherence to standards of care and with technological breakthroughs in biological agents, is giving new hope to the problem of impaired healing.