Effect of glycaemic control on apoptosis in diabetic wounds

Pathological insights into cell death pathways in diabetic wound healing

Diabetic foot ulcers (DFUs) are a microvascular complication that affects almost 21 % of the diabetic population. DFUs are characterized by lower limb abnormalities, chronic inflammation, and a heightened hypoxic environment. The challenge of healing these chronic wounds arises from impaired blood flow, neuropathy, and dysregulated cell death processes. The pathogenesis of DFUs involves intricate mechanisms of programmed cell death (PCD) in different cell types, which include keratinocytes, fibroblasts, and endothelial cells. The modes of cell death comprise apoptosis, autophagy, ferroptosis, pyroptosis, and NETosis, each defined by distinct biochemical hallmarks. These diverse mechanisms contribute to tissue injury by inducing neutrophil extracellular traps and generating cellular stressors like endoplasmic reticulum stress, oxidative stress, and inflammation. Through a comprehensive review of experimental studies identified from literature databases, this review synthesizes current knowledge on the critical signaling cascades implicated in programmed cell death within the context of diabetic foot ulcer pathology.

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.

Diabetic leg and foot ulcers: how district nurses can promote wound healing through blood glucose control

Diabetes is a chronic and often life-long condition that is a consequence of the blood glucose level being too high (National Institute for Health and Clinical Excellence (NICE), 2019). Diabetes covers a range of conditions such as type 1 diabetes, type 2 diabetes and gestational diabetes. It has been well documented that uncontrolled blood glucose levels can lead to further circulatory damage, which impedes the wound healing process and often results in chronic wounds that do not heal. This article uses data collected from an audit and explores how district nursing teams can improve wound healing for those living at home with diabetic ulcers (DUs) by regularly monitoring blood glucose levels. This is followed by a discussion on how district nurses can support their team to adapt best practice, and the benefits of regularly checking blood glucose levels, even for service users that manage their diabetes with diet or oral medication. The article also explores how the multidisciplinary team can be accessed and used efficiently and how leadership skills can improve service user care and safety.

The Antimicrobial Effects of Bacterial Cellulose Produced by Komagataeibacter intermedius in Promoting Wound Healing in Diabetic Mice

As a conventional medical dressing, medical gauze does not adequately protect complex and hard-to-heal diabetic wounds and is likely to permit bacterial entry and infections. Therefore, it is necessary to develop novel dressings to promote wound healing in diabetic patients. Komagataeibacter intermedius was used to produce unmodified bacterial cellulose, which is rarely applied directly to diabetic wounds. The produced cellulose was evaluated for wound recovery rate, level of inflammation, epidermal histopathology, and antimicrobial activities in treated wounds. Diabetic mices' wounds treated with bacterial cellulose healed 1.63 times faster than those treated with gauze; the values for the skin indicators in bacterial cellulose treated wounds were more significant than those treated with gauze. Bacterial cellulose was more effective than gauze in promoting tissue proliferation with more complete epidermal layers and the formation of compact collagen in the histological examination. Moreover, wounds treated with bacterial cellulose alone had less water and glucose content than those treated with gauze; this led to an increase of 6.82 times in antimicrobial protection, lower levels of TNF-α and IL-6 (39.6% and 83.2%), and higher levels of IL-10 (2.07 times) than in mice wounds treated with gauze. The results show that bacterial cellulose produced using K. intermedius beneficially affects diabetic wound healing and creates a hygienic microenvironment by preventing inflammation. We suggest that bacterial cellulose can replace medical gauze as a wound dressing for diabetic patients.

The Foreign Body Response to an Implantable Therapeutic Reservoir in a Diabetic Rodent Model

Advancements in type 1 diabetes mellitus treatments have vastly improved in recent years. The move toward a bioartificial pancreas and other fully implantable systems could help restore patient's glycemic control. However, the long-term success of implantable medical devices is often hindered by the foreign body response. Fibrous encapsulation "walls off" the implant to the surrounding tissue, impairing its functionality. In this study we aim to examine how streptozotocin-induced diabetes affects fibrous capsule formation and composition surrounding implantable drug delivery devices following subcutaneous implantation in a rodent model. After 2 weeks of implantation, the fibrous capsule surrounding the devices were examined by means of Raman spectroscopy, micro-computed tomography (μCT), and histological analysis. Results revealed no change in mean fibrotic capsule thickness between diabetic and healthy animals as measured by μCT. Macrophage numbers (CCR7 and CD163 positive) remained similar across all groups. True component analysis also showed no quantitative difference in the alpha-smooth muscle actin and extracellular matrix proteins. Although principal component analysis revealed significant secondary structural difference in collagen I in the diabetic group, no evidence indicates an influence on fibrous capsule composition surrounding the device. This study confirms that diabetes did not have an effect on the fibrous capsule thickness or composition surrounding our implantable drug delivery device. Impact Statement Understanding the impact diabetes has on the foreign body response (FBR) to our implanted material is essential for developing an effective drug delivery device. We used several approaches (Raman spectroscopy and micro-computed tomography imaging) to demonstrate a well-rounded understanding of the diabetic impact on the FBR to our devices, which is imperative for its clinical translation.

The intensity of the foreign body response to polyether-polyurethane implant in diabetic mice is strain-dependent

A number of genetic factors have been linked to the development of diabetes, a condition that often requires implantable devices such as glucose sensors. In normoglycaemic individuals, this procedure induces a foreign body reaction (FBR) that is detrimental to bioimplant functionality. However, the influence of the genetic background on this reaction in diabetes has not been investigated. We examined the components of FBR (capsule thickness, collagen deposition, mast cell and foreign body giant cell number) in subcutaneous implants of polyether polyurethane (SIPP) in streptozotocin (STZ)-induced diabetes in Swiss, C57BL/6 and Balb/c mice. The fasting blood glucose levels before STZ injections were 133.5 ± 5.1 mg/dL, after the treatment increased 68.4% in Swiss mice, 62.4% in C57BL/6 and 30.9% in Balb/c mice. All FBR features were higher in implants of Swiss and C57BL/6 mice compared with those in implants of Balb/c. Likewise, the apoptotic index was higher in implants of diabetic Swiss and C57BL/6 mice whose glycaemic levels were the highest. Our findings show an association between the severity of hyperglycaemic levels and the intensity of the FBR to SIPP. These important strain-related differences in susceptibility to diabetes and the intensity of the FBR must be considered in management using implantable devices in diabetic individuals.

Does Perioperative Hemoglobin A1c Level Affect the Incidence, Pattern and Mortality of Lower Extremity Amputation?

BACKGROUND

We hypothesized that perioperative HbA1c influenced the pattern and outcomes of Lower Extremity Amputation (LEA).

METHODS

A retrospective analysis was conducted for all patients who underwent LEA between 2000 and 2013. Patients were categorized into 5 groups according to their perioperative HbA1c values [Group 1 (<6.5%), Group 2 (6.5-7.4%), Group 3 (7.5-8.4%), Group 4 (8.5-9.4%) and Group 5 (≥9.5%)]. We identified 848 patients with LEA; perioperative HbA1c levels were available in 547 cases (Group 1: 18.8%, Group 2: 17.7%, Group 3: 15.0%, Group 4: 13.5% and Group 5: 34.9%). Major amputation was performed in 35%, 32%, 22%, 10.8% and 13.6%, respectively.

RESULTS

The overall mortality was 36.5%; of that one quarter occurred during the index hospitalization. Mortality was higher in Group 1 (57.4%) compared with Groups 2-5 (46.9%, 38.3%, 36.1% and 31.2%, respectively, p=0.001). Cox regression analysis showed that poor glycemic control (Group 4 and 5) had lower risk of mortality post-LEA [hazard ratio 0.57 (95% CI 0.35-0.93) and hazard ratio 0.46 (95% CI 0.31-0.69)]; this mortality risk persisted even after adjustment for age and sex but was statistically insignificant. The rate of LEA was greater among poor glycemic control patients; however, the mortality was higher among patients with tight control.

CONCLUSION

The effects of HbA1c on the immediate and long-term LEA outcomes and its therapeutic implications need further investigation.

A ‘Speed-Dating’ Model of Wound Care? Rapid, High-Volume Assessment of Patients With Diabetes in a Multidisciplinary Foot Wound Clinic

Background Diabetes is a major risk factor for foot ulceration and leg amputation, but the effect of intensive glycaemic control on wound healing is unknown. While an interdisciplinary approach has been shown to be important in the management of diabetic foot ulcer (DFU), there is no standardised definition of such an interdisciplinary team.

Objective To investigate the role of an opportunistic, rapid-access, inter-disciplinary model of diabetes care at a foot wound clinic.

Methods A retrospective case-control study of patients with DFUs attending a diabetes foot wound clinic over a 6-month period. Outcomes in patients who were seen by a rapid-access interdisciplinary team (RAIT) consisting of an endocrinologist, diabetes educator and dietician during the standard wound care those who were not seen by this team were compared.

Results Fifty-five patients were seen by the RAIT and 64 control patients were not seen by this team during their attendance of a diabetes foot wound clinic. Patients in the intervention group had non-significantly higher baseline HbA1c and a significantly larger proportion were active cigarette smokers. Both groups achieved comparable reduction in the total number of DFUs per patient (p=0.971). Patients in the intervention group had a 60.1% reduction in wound size compared to 52.4% reduction in control group (p=0.526).

Conclusion Our study shows that the use of a rapid-access interdisciplinary team to assess and manage patients’ diabetes in a foot wound clinic is feasible. Patients with higher-risk diabetes foot wounds exposed to RAIT had comparable wound healing outcomes to lower risk patients.

Factors associated with lower-extremity amputation in patients with diabetic foot ulcers in a Chinese tertiary care hospital

Providing a better understanding of the risk factors for amputation in this particular region, Hunan province, in China might help patients with diabetic foot ulcers receive timely and appropriate medical care and help prevent amputation. Diabetic foot ulcer patients referred to the Third Xiangya Hospital during the period between December 2014 and September 2018 were enrolled. Participants who underwent amputations and received conservative treatments were compared using univariate and multivariate analyses to identify the independent predictors of amputation. Those who required amputation presented significantly higher levels of white blood cell counts, platelet counts, erythrocyte sedimentation rate, C-reactive protein, and glycated haemoglobin (HbA1c) levels. However, levels of haemoglobin, postprandial plasma C-peptide, triglyceride, high-density lipoprotein cholesterol, albumin, and uric acid were decreased in patients with amputations. Patients with more advanced Wagner grades had much higher rates of amputation. Multivariable-adjusted odds ratios in stepwise logistic regression model was 1.317 for HbA1c (95% CI: 1.015-1.709), 0.255 for triglyceride (95% CI: 0.067-0.975), and 20.947 for Wagner grades (95% CI: 4.216-104.080). Independent risk factors for amputation in these Chinese diabetic foot ulcer patients included an elevated HbA1c level, lower triglyceride level, and higher Wagner grades.

Oleogel-S10 Phase 3 study "EASE" for epidermolysis bullosa: study design and rationale

Background

Epidermolysis bullosa (EB) is a group of rare, genetic diseases that affect the integrity of epithelial tissues, most notably the skin. Patients experience recurrent skin wounding, with severity depending on type, sub-type, and mutation. Oleogel-S10, a formulation of birch bark extract, has demonstrated efficacy in a Phase 2 trial assessing re-epithelialization of wounds in EB. EASE (NCT03068780, EudraCT 2016–002066-32) is a randomized, Phase 3, placebo-controlled study designed to determine the efficacy of Oleogel-S10 versus placebo in patients with EB.

Methods

EASE is a Phase 3, two-phase study comprising a 90-day, double-blind, randomized, placebo-controlled phase, followed by 24 months of open-label, single-arm follow-up. Patients with junctional EB, dystrophic EB, or Kindler syndrome and target wounds (10 - 50cm²) present for > 21 days and < 9 months, are randomized in a 1:1 ratio to receive wound dressings according to local standard of care with or without Oleogel-S10. Placebo is based on the Oleogel-S10 vehicle, which is sunflower oil formulated to have a consistency indistinguishable from that of the active product. The primary endpoint of the trial, directed by the US health authority according to the required study endpoints for chronic cutaneous ulcer and burn wounds, is to compare the efficacy of Oleogel-S10 versus placebo according to the proportion of patients with complete closure of the target wound within 45 ± 7 days of treatment. Additional EB-focused endpoints include wound burden, patient-reported outcomes, and safety.

Results

Results of the primary endpoint are anticipated to be available by H2 2019.

Trial registration

ClinicalTrials.gov, NCT03068780. EudraCT, 2016–002066-32. Registered on 3 March 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3362-z) contains supplementary material, which is available to authorized users.

Efficacy of comprehensive ozone therapy in diabetic foot ulcer healing

BACKGROUND

Diabetic foot ulcer is one of the common complications of diabetes disease that is costly and difficult to treat. This problem can lead to morbidity and even mortality. Ozone is a gas that can optimize cellular metabolism and, because of its antioxidant and antibacterial effects, can help the better healing of diabetic foot ulcer.

METHOD

Two hundred patients, aged 18-85 with diabetic foot ulcers ranging from grade 1 to 4 according to Wagner classification in two groups were studied. Group 1 was treated by full ozone therapy besides the standard regular DFU treatment while group two just was received routine diabetic foot care. Wound size, wound grade, healing time, Fasting blood sugar and inflammatory biomarker before and after treatment were checked.

RESULTS

All patients have had complete wound closure in the ozone group. The mean age of the patients included in the results was 59.03 ± 12.593 and 53.5 ± 10.212 for ozone group and control group. The baseline average surface area of ulcers was 13.41 ± 14.092 cm² (range 1-70 cm²) in ozone group and 12.72 ± 0.911 (range 1_64 cm²) in the control group. Average healing time was 69.44 ± 36.055 days (range 15-180 days), which is significantly lower than the median healing time measured in the control group and some previous studies.

CONCLUSION

Our study results support the efficacy of ozone therapy especially in its comprehensive use in DFU healing and reduction in the chances of infection and amputation.

HbA1c and Lower Extremity Amputation Risk in Patients With Diabetes

In this meta-analysis, we aimed to assess glycosylated hemoglobin (HbA1c) level and lower extremity amputation (LEA) risk in patients with diabetes. Systematic computerized searches of the PubMed and Web of Knowledge were performed. We compared HbA1c level between groups with LEA and without LEA by meta-analysis; we also examined the dose–response relationship between HbA1c level and LEA risk. Sixteen studies were included in the meta-analysis. Eleven studies with 43 566 patients compared HbA1c between groups with and without LEA. The mean HbA1c (%) ranged from 8.3 to 12.5 in the group with LEA and from 7.4 to 11.3 in the group without LEA. The pooled weighted mean difference was 1.110 (95% confidence interval = 0.510-1.709; Z = 3.63, P = .008). The funnel plot was symmetrical, and Begg’s test ( z = 0.00, P = 1.000) and Egger’s test ( t = −0.02, P = .984) suggested no significant publication bias. Six studies with 109 933 patients included in the dose–response meta-analysis. The LEA incidence ranged from 0.3% to 14.6% between different HbA1c levels. Dose–response meta-analysis showed statistically significant association between HbA1c and LEA risk (χ2 = 65.51, P = .000). In linear model, the odds ratio for LEA incidence was 1.229 (95% confidence interval = 1.169-1.292) for every 1% HbA1c increase. In the spline model, the odds ratio of LEA risk increased with HbA1c levels, especially when HbA1c ranged from 5% to 9%. Our meta-analysis indicates that high level of HbA1c is an important risk factor for LEA in patients with diabetes. This evidence supports the strategy for lowering glucose levels to reduce amputation in patients with diabetes.

Akt/hypoxia-inducible factor-1α signaling deficiency compromises skin wound healing in a type 1 diabetes mouse model

The aim of the present study was to investigate the mechanisms for impaired skin wound healing in subjects with diabetes. Type 1 diabetes (T1DM) was induced in BALB/c mice using streptozotocin. One month after the establishment of the T1DM mouse model, a wound was formed on the back of the mice, and tissues from the wounds and the margins were collected on days 0, 3, 7 and 10. Protein levels of cluster of differentiation 31 (CD31) were detected using immunohistochemistry, and the mRNA levels of Akt, hypoxia-inducible factor-1α (Hif-1α), vascular endothelial growth factor (Vegf), VEGF receptor 2 (Vegfr2), stromal cell-derived growth factor-1α (Sdf-1α) and CXC chemokine receptor 4 (Cxcr4) were determined using reverse transcription-quantitative polymerase chain reaction analysis. The corresponding protein levels were determined using western blotting. The skin wound healing rate in the T1DM mice was significantly lower than that in the control mice, and the protein level of CD31 in the wounded skin of the T1DM mice was significantly decreased. Furthermore, the overall mRNA levels of Akt, Hif-1α, Vegf, Vegfr2, Sdf-1α and Cxcr4 in the T1DM mice were significantly lower than those in the control mice, and similar trends were observed in the protein levels. In conclusion, skin wound healing was impaired in the T1DM mice, and this may have been caused by a deficiency of Akt/HIF-1α and downstream signaling, as well as delayed angiogenesis.

Direct effect of streptozotocin on periodontal ligament cells through myeloid cell leukemia-1

OBJECTIVE

We hypothesized that streptozotocin (STZ) has a direct impact on periodontal ligament cell (PDL) damage as a potential direct inducer of periodontitis.

BACKGROUND

Since diabetes was accepted as one of the risk factors for the development of periodontal disease, various scientific studies have been undertaken in the STZ-induced periodontal disease models. STZ induces β-cell damage and subsequent diabetes development in vivo. Until now, assessment of the impacts of STZ-induced experimental diabetes on periodontitis has generally been conducted on the fundamental assumption that STZ have no direct action on PDL and its function. However, several recent studies suggest that STZ also directly affect many different biological functions in various tissues or organs.

MATERIAL AND METHODS

To assess the apoptotic effects of STZ on PDLs, they were treated with or without STZ at different concentrations. Qualitative estimation of apoptotic cell death was obtained by live/dead assay. The expression levels of apoptosis-related proteins were evaluated by western blot analysis.

RESULTS

STZ inhibits growth and induces apoptosis in PDLs in a dose-dependent manner. Furthermore, STZ dramatically induced Mcl-1 downregulation in a proteasome-dependent manner and thereby induced apoptosis of PDLs through the Bak/Bax apoptotic signaling pathway.

CONCLUSION

Our results support the hypothesis that suppression of the cellular Mcl-1 levels by STZ may be at least partly attributed to the development of periodontitis in STZ-induced diabetic animal models.

Foreign body response to subcutaneous implants in diabetic rats

Implantation of synthetic matrices and biomedical devices in diabetic individuals has become a common procedure to repair and/or replace biological tissues. However, an adverse foreign body reaction that invariably occurs adjacent to implant devices impairing their function is poorly characterized in the diabetic environment. We investigated the influence of this condition on the abnormal tissue healing response in implants placed subcutaneously in normoglycemic and streptozotocin-induced diabetes in rats. In polyether-polyurethane sponge discs removed 10 days after implantation, the components of the fibrovascular tissue (angiogenesis, inflammation, fibrogenesis, and apoptosis) were assessed. Intra-implant levels of hemoglobin and vascular endothelial growth factor were not different after diabetes when compared with normoglycemic counterparts. However, there were a lower number of vessels in the fibrovascular tissue from diabetic rats when compared with vessel numbers in implants from non-diabetic animals. Overall, the inflammatory parameters (neutrophil accumulation - myeloperoxidase activity, tumor necrosis factor alpha, and monocyte chemotactic protein-1 levels and mast cell counting) increased in subcutaneous implants after diabetes induction. However, macrophage activation (N-acetyl-β-D-glucosaminidase activity) was lower in implants from diabetic rats when compared with those from normoglycemic animals. All fibrogenic markers (transforming growth factor beta 1 levels, collagen deposition, fibrous capsule thickness, and foreign body giant cells) decreased after diabetes, whereas apoptosis (TUNEL) increased. Our results showing that hyperglycemia down regulates the main features of the foreign body reaction induced by subcutaneous implants in rats may be relevant in understanding biomaterial integration and performance in diabetes.

Hyperglycemia is associated with lower levels of urokinase-type plasminogen activator and urokinase-type plasminogen activator receptor in wound fluid

AIMS

Wounds in patients with hyperglycemia show impaired healing. Plasminogen activation is crucial in several overlapping phases of wound healing process. In this study, we aimed i) to compare acute wound fluid in patients with hyperglycemia and normoglycemia, ii) to focus on the elements of plasminogen activation in the wound fluid, and iii) to determine if the acute wound fluid characteristics are associated with surgical site infections.

METHODS

In a cohort of 54 patients, a closed suction drain was placed in the wound above the anterior abdominal wall fascia under the skin in order to collect postoperative acute wound fluid samples for 3 following days after colorectal surgery. Patients were classified as normoglycemic (n=25) or hyperglycemic (n=29; 17 with type 2 diabetes and 12 with stress induced hyperglycemia). Surgical site infection was defined according to the Centers for Disease Control criteria. The levels of urokinase-type plasminogen activator (uPA), urokinase-type plasminogen activator receptor (uPAr), plasminogen activator inhibitor-1 (PAI-1), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and fibroblast growth factor-1 (FGF-1) were measured in the wound fluid.

RESULTS

Compared to normoglycemic subjects, patients with hyperglycemia had significantly lower levels of uPA and uPAr in the wound fluid despite similar or even higher circulating levels. There was no significant difference in IL-1β, TNF-α, PAI-1 and FGF-1 levels. In the whole study population, the wound fluid levels of uPA and uPAr were negatively correlated with circulating glucose levels. No difference was detected in the wound fluid characteristics of patients with and without surgical site infection.

CONCLUSION

Patients with hyperglycemia exhibit decreased levels of uPA and uPAr in the wound fluid, suggesting a local failure in plasminogen activation at the wound site.

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.

Apoptosis of periodontium cells in streptozototocin- and ligature-induced experimental diabetic periodontitis in rats

OBJECTIVE

The aim of this study was to investigate the presence of apoptosis of periodontium cells in streptozototocin- and ligature-induced experimental diabetic periodontitis in rats.

MATERIALS AND METHODS

Sixty-two 6-week-old male Sprague-Dawley (SD) rats were randomly divided into three groups: the diabetic periodontitis group (group DP; n = 22), periodontitis group (group P; n = 20) and normal control group (group N; n = 20). Diabetes was induced by intraperitoneal injection of streptozototocin (STZ). Periodontitis was initiated by ligating floss around maxillary second molars. The animals were sacrificed at 3 and 6 weeks after ligature placement in the P and DP groups. Maxillary dentoalveolar segments were isolated and were prepared for morphometric analysis of alveolar bone loss (ABL) and for histological analysis.

RESULTS

ABL was significantly increased in group DP compared with group P (p < 0.05). The number of PDL fibroblasts, osteoblasts and osteocytes in group DP was decreased compared with group P (p < 0.05). Inter-group analysis revealed higher osteoclast numbers in the inflammatory area of group DP and group P when compared with group N (p < 0.05). Also, compared with group P, group DP had more higher osteoclast numbers (p < 0.05). Periodontitis and diabetic periodontitis also increased apoptosis of fibroblasts, osteoblasts and osteocytes. The percentage of these apoptotic cells was ∼ 2-fold higher in group DP vs group P.

CONCLUSIONS

The results of these studies suggest that diabetes may have a negative effect on the periodontium by increasing the formation of osteoclasts and enhancing apoptosis of fibroblasts, osteoblasts and osteocytes in the periodontal tissue.

Apoptosis in adhesions and the adhesion-tendon gliding interface: relationship to adhesion-tendon gliding mechanics

PURPOSE

Adhesion formation is closely related to tendon-gliding function. We aimed to investigate apoptosis (programmed cell death) in adhesions and tendons and study its relationship to the mechanics of adhesions and healing tendons.

METHODS

The flexor digitorum profundus tendons of 30 long toes in 15 chickens were completely transected and repaired surgically. At postoperative weeks 4, 6, and 8, tendon-gliding excursions were tested and adhesion scores were recorded. Tendons and surrounding adhesions were then harvested for analysis of apoptosis using in situ terminal deoxynucleotidyl transferase dUTP (deoxyuridine triphosphate) nick end labeling assay. Three-dimensional image reconstruction was used to provide an overall view of cellular distribution in tendons and adhesions. Finally, we analyzed the correlation between the apoptotic index measured at the adhesions and the gliding excursions. Ten uninjured tendons served as normal controls.

RESULTS

Apoptosis was found to be a dominant cellular event in the adhesion tissues at both the adhesion-tendon gliding interface and the adhesion core. The apoptotic index in the adhesions was generally above 20% to 50%. The apoptotic index was significantly higher in the adhesions than in the junction region of the cut tendon ends at weeks 4, 6, and 8. A higher apoptotic index in the adhesions significantly correlated to lower tendon excursions at week 6.

CONCLUSIONS

Apoptosis in adhesions and at the adhesion-tendon interface is a prominent event in the tendon-healing process. The tendons exhibiting a lower tendon-gliding amplitude, meaning more severe adhesions, tended to have a greater apoptotic index in their adhesions during a certain period of the tendon-remodeling process.

CLINICAL RELEVANCE

Apoptosis in the adhesions and at the adhesion-tendon interface may contribute remarkably to the fate of adhesions and the restoration of the tendon gliding surface, which may be closely related to the tendon function.

Glucose toxic effects on granulation tissue productive cells: the diabetics' impaired healing

Type 2 diabetes mellitus is a metabolic noncommunicable disease with an expanding pandemic magnitude. Diabetes predisposes to lower extremities ulceration and impairs the healing process leading to wound chronification. Diabetes also dismantles innate immunity favoring wound infection. Amputation is therefore acknowledged as one of the disease's complications. Hyperglycemia is the proximal detonator of systemic and local toxic effectors including proinflammation, acute-phase proteins elevation, and spillover of reactive oxygen and nitrogen species. Insulin axis deficiency weakens wounds' anabolism and predisposes to inflammation. The systemic accumulation of advanced glycation end-products irreversibly impairs the entire physiology from cells-to-organs. These factors in concert hamper fibroblasts and endothelial cells proliferation, migration, homing, secretion, and organization of a productive granulation tissue. Diabetic wound bed may turn chronically inflammed, procatabolic, and an additional source of circulating pro-inflammatory cytokines, establishing a self-perpetuating loop. Diabetic fibroblasts and endothelial cells may bear mitochondrial damages becoming prone to apoptosis, which impairs granulation tissue cellularity and perfusion. Endothelial progenitor cells recruitment and tubulogenesis are also impaired. Failure of wound reepithelialization remains a clinical challenge while it appears to be biologically multifactorial. Ulcer prevention by primary care surveillance, education, and attention programs is of outmost importance to reduce worldwide amputation figures.

A comparison of wound healing rate following treatment with aftamed and chlorine dioxide gels in streptozotocin-induced diabetic rats

Background and Purpose. This study aimed to evaluate the wound healing activities of Aftamed and chlorine dioxide gels in streptozotocin-induced diabetic rats. Experimental Approach. Forty-eight Sprague Dawley rats were chosen for this study, divided into 4 groups. Diabetes was induced. Two-centimeter-diameter full-thickness skin excision wounds were created. Animals were topically treated twice daily. Groups 1, the diabetic control group, were treated with 0.2 mL of sterile distilled water. Group 2 served as a reference standard were treated with 0.2 mL of Intrasite gel. Groups 3 and 4 were treated with 0.2 mL of Aftamed and 0.2 mL of chlorine dioxide gels respectively. Granulation tissue was excised on the 10th day and processed for histological and biochemical analysis. The glutathione peroxidase ,superoxide dismutase activities and the malondialdehyde (MDA) levels were determined. Results. Aftamed-treated wounds exhibited significant increases in hydroxyproline, cellular proliferation, the number of blood vessels, and the level of collagen synthesis. Aftamed induced an increase in the free radical-scavenging enzyme activity and significantly reduced the lipid peroxidation levels in the wounds as measured by the reduction in the MDA level. Conclusions. This study showed that Aftamed gel is able to significantly accelerate the process of wound healing in diabetic rats.

Cellular apoptosis and proliferation in the middle and late intrasynovial tendon healing periods

PURPOSE

Cellular apoptosis might be an important molecular event in the middle or late healing periods of intrasynovial tendons, but this has not been studied. We aimed to investigate cellular apoptosis and corresponding cellular proliferation in the middle and late healing stages of intrasynovial tendons.

METHODS

The flexor digitorum profundus tendons of 48 long toes (24 chickens) were completely transected within the sheath region and were repaired surgically. At days 28, 42, 56, and 84 after surgery, tendons were harvested and sectioned. In situ terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to detect apoptotic cells. The sections were stained immunofluorescently with antibodies to proliferating cell nuclear antigen to assess proliferation and to Bcl-2 (an anti-apoptotic protein). Positively stained tenocytes were counted, and their distributional differences were verified in 3-dimensional images.

RESULTS

The repaired intrasynovial tendons exhibited generally greater apoptosis in the surface region than in the core. The differences were more remarkable in the extended region than in the junction region of the cut tendon. At the core of the junction site, apoptosis of tenocytes was pronounced at all time points, but it was less severe at the core of the extended region. The proliferating cell nuclear antigen-positive and Bcl-2-positive tenocytes decreased significantly and continually at days 28, 42, and 56, respectively; these tenocytes were at a minimum at days 56 and 84.

CONCLUSIONS

Apoptotic changes of tenocytes are most marked in the surface region and in the junction region of the healing tendon in the middle and late healing stages. Apoptosis in the core is less dramatic compared to that in the surface in the extended tendon regions. Cellular proliferation declines drastically and is minimal at days 56 and 84.

CLINICAL RELEVANCE

Tenocyte apoptosis in the middle and late stages might be an important event contributing to intrasynovial tendon remodeling, which affects the healing strength and formation of adhesions.

Altered fibroblast proliferation and apoptosis in diabetic gingival wounds

Although it is known that diabetes impairs oral wound healing, relatively little is known about the cellular parameters affected, particularly in connective tissue. This study investigated the hypothesis that diabetes impairs connective tissue formation in healing gingiva, and that impaired healing is associated with factors that decrease fibroblast numbers. Full-thickness wounds were created in the palatal gingiva of type 1 and type 2 diabetic and normoglycemic mice. Five days after wounding, diabetic mice had less epithelial wound coverage, less new connective tissue formation, and reduced fibroblast density (p < 0.05). This occurred with increased numbers of caspase-3- and TUNEL-positive fibroblasts, decreased fibroblast proliferation, increased nuclear translocation of the pro-apoptotic transcription factor FOXO1, and increased numbers of polymorphonuclear leukocytes, all of which were significant (p < 0.05). The results suggest that diabetes may decrease fibroblast numbers through increased apoptosis and reduced proliferation, both of which may be mediated through increased activation of FOXO1.

Impaired wound healing in mouse models of diabetes is mediated by TNF-alpha dysregulation and associated with enhanced activation of forkhead box O1 (FOXO1)

AIMS/HYPOTHESIS

The role of TNF-alpha in impaired wound healing in diabetes was examined by focusing on fibroblasts.

METHODS

Small excisional wounds were created in the db/db mice model of type 2 diabetes and normoglycaemic littermates, and in a streptozotocin-induced type 1 diabetes mouse model and control mice. Fibroblast apoptosis was measured by the TUNEL assay, proliferation by detection of proliferating cell nuclear antigen, and forkhead box O1 (FOXO1) activity by DNA binding and nuclear translocation. TNF-alpha was specifically inhibited by pegsunercept.

RESULTS

Diabetic wounds had increased TNF-alpha, fibroblast apoptosis, caspase-3/7 activity and activation of the pro-apoptotic transcription factor FOXO1, and decreased proliferating cell nuclear antigen positive fibroblasts (p < 0.05). TNF-alpha inhibition improved healing in the diabetic mice and increased fibroblast density. This may be explained by a decrease in fibroblast apoptosis and increased proliferation when TNF-alpha was blocked (p < 0.05). Although decreased fibroblast proliferation and enhanced FOXO1 activity were investigated in type 2 diabetes, they may also be implicated in type 1 diabetes. In vitro, TNF-alpha enhanced mRNA levels of gene sets related to apoptosis and Akt and p53 but not mitochondrial or cell-cycle pathways. FOXO1 small interfering RNA reduced gene sets that regulate apoptosis, Akt, mitochondrial and cell-cycle pathways. TNF-alpha also increased genes involved in inflammation, cytokine, Toll-like receptor and nuclear factor-kB pathways, which were significantly reduced by FOXO1 knockdown.

CONCLUSIONS/INTERPRETATION

These studies indicate that TNF-alpha dysregulation in diabetic wounds impairs healing, which may involve enhanced fibroblast apoptosis and decreased proliferation. In vitro, TNF-alpha induced gene sets through FOXO1 that regulate a number of pathways that could influence inflammation and apoptosis.

Molecular events of cellular apoptosis and proliferation in the early tendon healing period

PURPOSE

Cellular proliferation is accompanied by cellular apoptosis. In the healing digital flexor tendon, molecular events concerning cellular apoptosis have not been investigated. This study aimed to investigate the relationship between cellular apoptosis and proliferation in early tendon healing.

METHODS

The flexor digitorum profundus tendons of 50 long toes in 25 chickens were transected and were repaired surgically. On postoperative days 3, 7, 14, 21, and 28, we subjected tendons to in situ terminal deoxynucleotide transferase dUTP nick end labeling (TUNEL) assay to detect apoptotic cells, immunofluorescence staining with antibodies to proliferating cell nuclear antigen to assess proliferation, and Bcl-2, an anti-apoptotic protein, to assess responses suppressive to apoptosis. The positively labeled tenocytes were counted microscopically and compared statistically. We also stained sections with hematoxylin and eosin to observe their healing status. An additional 12 tendons (6 chickens) served as day 0 controls.

RESULTS

Compared with tendons at day 0, the healing tendons had notably greater cellularity in both epitenon and endotenon areas. The total number of cells and number of TUNEL-positive cells peaked at day 3. At days 7 to 21, the number of proliferating cell nuclear antigen-positive cells peaked. At days 7 and 14, the cells positively stained with Bcl-2 peaked. At days 14 to 28, the total number of cells and TUNEL-positive cells decreased significantly compared with those at days 3 and 7, yet the numbers remained greater than those on day 0.

CONCLUSIONS

Apoptosis in the healing tendons peaks at day 3, followed about 10 days later by the peak proliferation period. Because Bcl-2 serves to inhibit apoptosis, a later increase in Bcl-2-positive cells indicates that tendon apoptosis is inhibited. These findings indicate that tenocyte apoptosis is accelerated within several days after injury, followed by increases in cellular proliferation and activation of molecular events to inhibit apoptosis in 2 to 4 weeks.

Scarless fetal mouse wound healing may initiate apoptosis through caspase 7 and cleavage of PARP

INTRODUCTION

Apoptotic mechanisms are thought to be important in wound healing for the removal of inflammatory cells and evolution of granulation tissue. However, little is understood about the signal, propagation, and mechanisms responsible for triggering cell death in tissue injury, particularly during fetal wound repair. Understanding these signals may lead to insights regarding scarless wound healing. We hypothesized that differences in apoptosis would exist in mid- (E15) compared with late-gestational (E18) mice subjected to cutaneous wounds. We examined early apoptotic signals that may be initiated following tissue injury.

METHODS

Pregnant, time-dated mice underwent laparotomy and hysterotomy on embryonic day 15 (E15) and 18 (E18). Full-thickness, excisional cutaneous wounds were made on the dorsum of the fetuses and dorsal skin harvested 15 and 45 min after wounding. Unwounded dorsal skin from additional fetuses collected at the same time points served as controls. The skin was processed to obtain protein, then levels of caspase 3, caspase 7, and poly ADP-ribose polymerase (PARP) were measured by Western blot. Cyclophilin levels were measured to ensure equal loading of protein. Histone-associated DNA complex formation was examined to provide further evidence of cellular apoptosis.

RESULTS

There were no differences in total caspase 3 levels between E15 and E18 fetal tissue with or without wounding, nor was any cleavage of caspase 3 noted in any group. However, cleaved caspase 7 was present in the E15 skin with a >2-fold increase following wounding at both 15 and 45 min, yet absent in the E18 groups. Furthermore, levels of cleaved PARP were also increased by >2-fold at both 15 and 45 min in E15 wound groups, whereas a relatively small amount was only seen in the E18 wound groups at 45 min. DNA-histone fragmentation ELISA assay showed a 5-fold increase in the enrichment of histone-associated DNA fragments in the E15 wounded tissue compared with the time-matched controls at 45 min. This was not seen with the E18 tissue.

CONCLUSIONS

Previously, we demonstrated that cutaneous wounds in E15 fetal mice heal in a scarless manner, while similar wounds in E18 mice heal with scar formation. Results from our current work demonstrate differences in apoptosis in mid- compared with late-gestational mouse skin as well as shortly after wounding. Our results suggest that in mid-gestational wounds, activation of apoptotic pathways may be mediated through effector caspase 7 signals with inactivation of PARP. This initiation of apoptotic signals following tissue injury may play a role in scarless wound repair.

The pro-inflammatory environment in recalcitrant diabetic foot wounds

Lower extremity ulceration is one of the serious and long-term diabetic complications rendering a significant social burden in terms of amputation and quality-of-life reduction. Diabetic patients experience a substantial wound-healing deficit. These lesions are featured by an exaggerated and prolonged inflammatory reaction with a significant impairment in local bacterial invasion control. Experimental and clinical evidences document the deleterious consequences of the wound's pro-inflammatory phenotype for the repair process. From a biochemical standpoint, hyperinflammation favours wound matrix degradation, thus, amplifying a pre-existing granulation tissue productive cells' invasiveness and recruitment deficit. Tumour necrosis factor perpetuates homing of inflammatory cells, triggers pro-apoptotic genes and impairs reepithelialisation. Advanced glycation end-products act in concert with inflammatory mediators and commit fibroblasts and vascular cells to apoptosis, contributing to granulation tissue demise. Therapeutic approaches aimed to downregulate hyperinflammation and/or attenuate glucolipotoxicity may assist in diabetic wound healing by dismantling downstream effectors. These medical interventions are demanded to reduce amputations in an expanding diabetic population.

A Unique Waterskiing Injury Leading to a Necrotizing Foot Infection in an Insulin-Dependent Diabetic

Reports of waterskiing-related injuries are limited in the medical literature. The authors report a case of a unique waterskiing injury that progressed into a necrotizing foot infection in a well-controlled insulin-dependent diabetic. This case shows that with aggressive therapy, including hyperbaric oxygen treatments and use of a wound vacuum-assisted closure system, limbs can be saved.

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

Diabetics suffer increased infection followed by increased apoptosis of fibroblasts and bone-lining cells during the healing process. To investigate a potential mechanism, we inoculated Porphyromonas gingivalis into the scalp of type 2 diabetic (db/db) or control mice and inhibited tumor necrosis factor alpha (TNF-alpha) with etanercept. Mice were euthanized at the early phase of infection (21 hours) or during the peak repair of the bacteria-induced wound (8 days). At 21 hours, TNF-alpha inhibition significantly reduced fibroblast apoptosis and caspase-3 activity in both diabetic and normoglycemic mice (P < 0.05). During healing etanercept reduced fibroblast apoptosis and caspase-3 activity by almost 50% in diabetic but not normoglycemic mice (P < 0.05). Concomitantly, etanercept significantly increased fibroblast number by 31% and new matrix formation by 72% in diabetic mice. When bone was examined during healing, administration of the TNF-alpha blocker reduced apoptosis of bone-lining cells by 53%, increased their number by 48%, and enhanced new bone formation by 140% in the diabetic group (P < 0.05). The degree of connective tissue and osseous healing stimulated in the diabetic mice by anti-TNF-alpha treatment was within the range that is physiologically relevant. This enhanced healing may in part be explained by block-ing TNF-alpha-induced apoptosis of critical matrix-producing cells.

Apoptosis: a basic physiologic process in wound healing

Apoptosis, or programmed cell death, is a complex network of biochemical pathways for controlling such events in a cell. Apoptosis is essential, as its failure can lead to disease. Because apoptosis concerns the regulation of sequential events, including the removal of inflammatory cells and the evolution of granulation tissue into scar tissue, it has an essential role in wound repair. This article examines the literature and proposes that apoptosis features in the development of diabetic foot wounds. Hyperglycemia deregulates the sequential apoptotic events by multiple mechanisms, leading to delayed wound healing. Deregulated apoptosis is emerging as a prominent cause of delayed wound healing, especially in diabetic wounds, along with the well-known triad of peripheral vascular disease, neuropathy, and infection.

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Impaired diabetic wound healing constitutes a major health problem. The impaired healing is caused by complex factors such as abnormal keratinocyte and fibroblast migration, proliferation, differentiation, and apoptosis, abnormal macrophage polarization, impaired recruitment of mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs), and decreased vascularization. Diabetes-enhanced and prolonged expression of TNF-α also contributes to impaired healing. In this paper, we discuss the abnormal cell responses in diabetic wound healing and the contribution of TNF-α.