Effectiveness of Global Leadership Initiative on Malnutrition and Subjective Global Assessment for diagnosing malnutrition and predicting wound healing in patients with diabetic foot ulcers.

Malnutrition significantly hampers wound healing processes. This study aimed to compare the effectiveness of the Global Leadership Initiative on Malnutrition (GLIM) and Subjective Global Assessment (SGA) in diagnosing malnutrition and predicting wound healing in patients with diabetic foot ulcers (DFU). GLIM criteria were evaluated for sensitivity (SE), specificity (SP), positive predictive value, negative predictive value and kappa (κ) against SGA as the reference. Modified Poisson regression model and the DeLong test investigated the association between malnutrition and non-healing ulcers over 6 months. This retrospective cohort study included 398 patients with DFU, with a mean age of 66·3 ± 11·9 years. According to SGA and GLIM criteria, malnutrition rates were 50·8 % and 42·7 %, respectively. GLIM criteria showed a SE of 67·3 % (95 % CI 60·4 %, 73·7 %) and SP of 82·7 % (95 % CI 76·6 %, 87·7 %) in identifying malnutrition, with a positive predictive value of 80·0 % and a negative predictive value of 71·1 % (κ = 0·50) compared with SGA. Multivariate analysis demonstrated that malnutrition, as assessed by SGA, was an independent risk factor for non-healing (relative risk (RR) 1·84, 95 % CI 1·45, 2·34), whereas GLIM criteria were associated with poorer ulcer healing in patients with estimated glomerular filtration rate ≥ 60 ml/min/1·73m2 (RR: 1·46, 95 % CI 1·10, 1·94). SGA demonstrated a superior area under the receiver's operating characteristic curve for predicting non-healing compared with GLIM criteria (0·70 (0·65-0·75) v. 0·63 (0·58-0·65), P < 0·01). These findings suggest that both nutritional assessment tools effectively identify patients with DFU at increased risk, with SGA showing superior performance in predicting non-healing ulcers.

Glucose Metabolism Indices and the Development of Chronic Kidney Disease: A Cohort Study of Middle-Aged and Elderly Chinese Persons.

Objective: Chronic kidney disease (CKD) has become a major global health issue, and abnormalities of glucose metabolism are a risk factor responsible for development of CKD. We aimed to investigate associations between glucose metabolism indices and CKD in a Chinese population and determine which index is superior for predicting incident CKD. Methods: We performed a community-based population on 5232 subjects aged ≥40 years without baseline CKD. CKD was defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 or urinary albumin-to-creatinine ratio (UACR) ≥30 mg/g. We examined the associations of glucose metabolism indices, including fasting plasma glucose (FPG), 2-hour (2 h) oral glucose tolerance test (OGTT), hemoglobin A1c (HbA1c), fasting insulin level, homeostasis model assessment of insulin resistance (HOMA-IR), and HOMA-ß and the development of CKD. Results: With an average follow-up of 3.6 years, 6.4% of the subjects developed CKD. Pearson's correlation analysis revealed that FPG, HbA1c, fasting insulin, and HOMA-IR were all significantly correlated with UACR and eGFR. The association persisted in multivariate linear regression analysis adjusted for age and sex. Compared with other glucose indices, HOMA-IR exhibited the strongest associations with CKD in COX multivariate regression analysis (HR = 1.17, 95% CI: 1.04-1.31). Conclusion: HOMA-IR is superior to other routine indices of glucose metabolism for predicting the development of CKD in middle-aged Chinese persons. Screening with HOMA-IR may help prevent the development of CKD in the general population.

Replacing of sedentary behavior with physical activity and the risk of mortality in people with prediabetes and diabetes: a prospective cohort study.

BACKGROUND: Sedentary behavior is prevalent among people with diabetes and is associated with unfavorable cardiometabolic health. However, there is limited evidence regarding the impact of replacing sedentary time (ST) with physical activity on mortality in people with prediabetes and diabetes. We prospectively examined the association between accelerometer-measured ST and mortality among people with prediabetes and diabetes after adjusting for demographic characteristics, lifestyle factors, and moderate- to vigorous-intensity PA (MVPA). We further determined the effect of replacing ST with equal time of different types of physical activities on all-cause mortality. METHODS: We included 1242 adults with prediabetes and 1037 with diabetes from the National Health and Nutrition Examination Survey. Restricted cubic splines were fitted to determine the dose-response association between ST and overall mortality. Isotemporal substitution modeling was used to explore the hazard ratio (HR) effects of ST replacement. RESULTS: During a median follow-up of 14.1 years, 424 adults with prediabetes and 493 with diabetes died. Compared with the lowest tertile of ST, the multivariable-adjusted HRs for all-cause mortality in the highest tertile were 1.76 (95% confidence interval [CI] 1.19, 2.60) for participants with prediabetes and 1.76 (1.17, 2.65) for those with diabetes. Additionally, a linear association between ST and all-cause mortality was observed in adults with prediabetes and diabetes, with HRs for each 60 min/day increment in ST of 1.19 (1.10, 1.30) and 1.25 (1.12, 1.40), respectively. Isotemporal substitution results indicated that individuals with prediabetes whose ST was replaced by 30 min of light-intensity physical activity (LPA) and MVPA had 9% and 40% lower all-cause mortality, respectively. In people with diabetes, replacing sedentary behavior with an equivalent time of LPA and MVPA was also associated with mortality risk reduction (HR 0.89; 95% CI 0.84, 0.95 for LPA; HR 0.73; 95% CI 0.49, 1.11 for MVPA). CONCLUSIONS: Higher ST was associated in a dose-response manner with an increased risk of premature mortality among adults with prediabetes and diabetes. Statistically replacing ST with LPA was potentially beneficial for health in this high-risk population.

TSH levels within the normal range and risk of cardiovascular and all-cause mortality among individuals with diabetes.

BACKGROUND: Evidence regarding thyroid-stimulating hormone (TSH) levels within the normal range and mortality in adults with diabetes is scarce. This study aimed to identify the association between TSH levels and cardiovascular disease (CVD) and all-cause mortality among euthyroid patients with diabetes. METHODS: This prospective cohort study included 1830 adults with diabetes from the Third National Health and Nutrition Examination Survey III. Mortality outcomes were ascertained by linkage to National Death Index records through December 31, 2019. Participants were categorized by tertiles of TSH levels (low-normal, 0.39-1.30 mIU/L; medium-normal, 1.30-2.09 mIU/L; high-normal, 2.09-4.60 mIU/L). Multivariable Cox proportional hazards models were used to explore the association between TSH levels within the normal range and overall and CVD mortality. Furthermore, restricted cubic spline analyses were used to determine the nonlinear relationship between TSH levels and mortality. RESULTS: During a median follow-up of 17.1 years, 1324 all-cause deaths occurred, including 525 deaths from CVD. After multivariate adjustment, a U-shaped relationship was observed between TSH levels in euthyroid status and all-cause or CVD mortality among patients with diabetes (both P < 0.05 for nonlinearity). Compared with participants with medium-normal TSH levels, those with high-normal TSH levels had a significantly higher risk of all-cause (hazard ratio, 1.31; 95% confidence interval, 1.07-1.61) and CVD (1.52; 1.08-2.12) mortality. Similarly, low-normal TSH levels also increased all-cause (1.39; 1.12-1.73) and CVD (1.69; 1.17-2.44) mortality risk. In stratum-specific analyses, we found that high-normal TSH levels were associated with higher mortality risk in younger (< 60 years) patients with diabetes but not in older (≥ 60 years) participants. CONCLUSION: Low- and high-normal serum TSH levels were associated with increased all-cause and CVD mortality in euthyroid adults with diabetes. Further studies are needed to confirm the present observation in a wider population.

The association of adiponectin with risk of pre-diabetes and diabetes in different subgroups: cluster analysis of a general population in south China.

OBJECTIVE: Adiponectin is an adipocyte-derived hormone with an important role in glucose metabolism. The present study explored the effect of adiponectin in diverse population groups on pre-diabetes and newly diagnosed diabetes. METHODS: A total of 3300 individuals were enrolled and their data were collected in the analyses dataset from December 2018 to October 2019. Cluster analysis was conducted based on age, BMI, waistline, body fat, systolic blood pressure, triglycerides, and glycosylated hemoglobin 1c. Cluster analysis divided the participants into four groups: a young-healthy group, an elderly-hypertension group, a high glucose-lipid group, and an obese group. Odds ratio (OR) and 95% CIs were calculated using multivariate logistic regression analysis. RESULTS: Compared with the first quartile of adiponectin, the risk of pre-diabetes of fourth quartile was decreased 61% (aOR = 0.39, 95% CI (0.20-0.73)) in the young-healthy group; and the risk of diabetes of fourth quartile was decreased 85% (aOR = 0.15, 95% CI (0.02-0.67)) in the obese group. There were no significant correlations between the adiponectin level and diabetes/pre-diabetes in the other two groups. Additionally, receiver operating characteristic curve analysis indicated that adiponectin could significantly improve the diagnosis based on models in the young-healthy group (from 0.640 to 0.675) and the obese group (from 0.714 to 0.761). CONCLUSIONS: Increased adiponectin levels were associated with decreased risk of pre-diabetes in the young-healthy population, and with a decreased the risk of diabetes in the obese population. An increased adiponectin level is an independent protective factor for pre-diabetes and diabetes in a specific population in south China.

MiR-195-5p and miR-205-5p in extracellular vesicles isolated from diabetic foot ulcer wound fluid decrease angiogenesis by inhibiting VEGFA expression.

Diabetic foot ulcers are recalcitrant to healing, and poor angiogenesis is considered as the main contributing factor. We aimed to explore the effect of extracellular vesicles (EVs) derived from wound fluids on new vessel formation in diabetic foot ulcers. EVs were isolated from wound fluids of diabetic foot ulcers (DF-EVs). The inhibitory effect of DF-EVs on human umbilical vein endothelial cells (HUVECs) and wound healing was tested. To elucidate the potential mechanism of these effects, we screened the differentially expressed microRNAs (miRNAs) in DF-EVs via microarray analysis and verified the upregulation of miR-195-5p and miR-205-5p in DF-EVs via quantitative real-time polymerase chain reaction (qRT-PCR). Further dual-luciferase reporter assays and overexpression experiments proved these two miRNAs inhibited the expression of vascular endothelial growth factor A (VEGFA) directly to the 3' untranslated region (UTR) of VEGFA and, in turn, promoted an inhibitory effect of DF-EVs on angiogenesis and wound healing in patients with diabetic foot ulcers. Our study shows EVs in the wound fluids of diabetic foot ulcer lesions carrying antiangiogenic miR-195-5p and miR-205-5p negatively regulated angiogenesis and wound healing in patients with diabetic foot.

Association between uric acid lowering and renal function progression: a longitudinal study.

BACKGROUND: This study aimed to explore the association between uric acid lowering and renal function. MATERIALS AND METHODS: We conducted a population-based cohort study with 1,534 subjects for 4 years from 2012 to 2016. The population was divided into four groups according to the interquartile range of changes in serum uric acid with quartile 1 representing lower quarter. Renal function decline was defined as eGFR decreased more than 10% from baseline in 2016. Renal function improvement was defined as eGFR increased more than 10% from baseline in 2016. Cox regression analysis was used to calculate the hazard ratio (HR) and 95% confidence interval (CI). RESULTS: In the adjusted Cox regression models, compared to quartile 4, quartile 1 (HR = 0.64, 95% CI [0.49-0.85]), quartile 2 (HR = 0.65, 95% CI [0.50-0.84]) and quartile 3 (HR = 0.75, 95% CI [0.58-0.96]) have reduced risk of renal function decline. An increasing hazard ratio of renal function improvement was shown in quartile 1 (HR = 2.27, 95% CI [1.45-3.57]) and quartile 2 (HR = 1.78, 95% CI [1.17-2.69]) compared with quartile 4. CONCLUSIONS: Uric acid lowering is associated with changes in renal function. The management of serum uric acid should receive attention in clinical practice and is supposed to be part of the treatment of chronic kidney disease.

Association of gonadal hormones and sex hormone binding globulin with risk of diabetes: A cohort study in middle-aged and elderly Chinese males.

AIM: Late-onset hypogonadism in men is related to the development of diabetes. The association of gonadal hormones, sex hormone binding globulin with diabetes has been studied in various studies. However, there is no cohort study on the relationship between gonadal hormone, sex hormone binding globulin and diabetes in Chinese. We aimed to provide an insight into the possible association in middle-aged and elderly Chinese males. METHODS: We included a population sample of 673 subjects aged 40 years or older. Total testosterone (TT), sex hormone binding globulin (SHBG), follicle-stimulating hormone (FSH) and luteinising hormone (LH) were detected. The homeostasis model assessment of insulin resistance (HOMA-IR) was calculated to estimate insulin sensitivity. Diabetes was diagnosed according to the 2010 American Diabetes Association criteria. RESULTS: With an average follow-up time of 3.2 ± 0.5 years, 9.8% of participants had developed diabetes. The prevalence of diabetes was decreased according to increasing SHBG quartiles (Q1:13.1%, Q2: 12.0%, Q3: 11.2%, Q4: 3.0%, P for trend < .0001) and TT (Q1:16.0%, Q2: 7.9%, Q3: 9.0%, Q4: 6.4%, P for trend < .0001). The ORs of diabetes for increasing SHBG quartiles were 4.52 (95% CI 1.40-14.57), 4.32 (95% CI 1.33-14.06), 3.89 (95% CI 1.21-12.50) and 1.00 (reference) respectively. But the odds of prevalent diabetes were not increased in different quartiles of TT, FSH and LH. In subgroup analyses, the relationship between SHBG and risk of incident diabetes was significantly increased in the population aged over 60, without insulin resistance and with eGFR < 90 mL/min per 1.73 m2 . CONCLUSIONS: Compared with gonadal hormones, a lower level of SHBG is independently associated with the risk of diabetes in middle-aged and elderly Chinese males.

Novel Long Noncoding RNA lnc-URIDS Delays Diabetic Wound Healing by Targeting Plod1.

Impaired wound healing is one of the main causes of diabetic foot ulcerations. However, the exact mechanism of delayed wound healing in diabetes is not fully understood. Long noncoding RNAs (lncRNAs) are widely involved in a variety of biological processes and diseases, including diabetes and its associated complications. In this study, we identified a novel lncRNA, MRAK052872, named lncRNA UpRegulated in Diabetic Skin (lnc-URIDS), which regulates wound healing in diabetes. lnc-URIDS was highly expressed in diabetic skin and dermal fibroblasts treated with advanced glycation end products (AGEs). lnc-URIDS knockdown promoted migration of dermal fibroblasts under AGEs treatment in vitro and accelerated diabetic wound healing in vivo. Mechanistically, lnc-URIDS interacts with procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (Plod1), a critical enzyme responsible for collagen cross-linking. The binding of lnc-URIDS to Plod1 results in a decreased protein stability of Plod1, which ultimately leads to the dysregulation of collagen production and deposition and delays wound healing. Collectively, this study identifies a novel lncRNA that regulates diabetic wound healing by targeting Plod1. The findings of the current study offer some insight into the potential mechanism for the delayed wound healing in diabetes and provide a potential therapeutic target for diabetic foot.

Obesity-associated secondary hypogonadism in young and middle-aged men in Guangzhou: A single-centre cross-sectional study.

AIM: Male obesity-associated secondary hypogonadism (MOSH) is becoming a public health issue. We aimed to know MOSH among young and middle-aged men in our hospital, to analyse their sex hormones and other index, and to determine leptin as a risk factor for MOSH. METHODS: In total, 258 men (ages ranging from 20 to 60, mean 38 ± 15) were enrolled in this study, and 242 of these men had their complete data, body mass index (BMI), waist circumference and sex hormones retrospectively investigated. The leptin and lipid levels were also evaluated, and comparisons were made between young (20-39 years old) and middle-aged (40-60 years old) men. RESULTS: Among all the participants, 7 were thin, with a BMI < 18.5 kg/m2 , 95 had a normal BMI (18.5 ≤ BMI < 23.9 kg/m2 ), 87 (35.9%) were overweight (24 ≤ BMI ≤ 27.9 kg/m2 ) and 53 (21.9%) were obese (BMI ≥ 28 kg/m2 ), 173 (71.5%) had a waist sized ≥ 85 cm. Among the 242 men, 104 (43%) had hypogonadism (TT ≤ 331.412 ng/dL). Compared with the men of normal weight, the level of testosterone of the obese men decreased (P = .006), while the level of serum lipids (including total cholesterol, TG and low-density lipoprotein cholesterol, P < .05) was elevated, higher UA, FSH and leptin were also present in the obese men. There were 83 (34.2%) men with MOSH. Compared with middle-aged men with MOSH, the FSH in young men was significantly reduced (P < .05); no significant increase in estradiol was observed in the MOSH group. The leptin levels in the MOSH group were significantly higher than those in the hypogonadism only group (P < .001). CONCLUSION: Obesity increases the prevalence of hypogonadism. The decrease in testosterone levels in young men maybe due to inhibition of the hypothalamic pituitary gonadal axis. Leptin is an independent risk factor for MOSH.

Lipid accumulation product and late-onset hypogonadism in middle-aged and elderly men: results from a cross-sectional study in China.

OBJECTIVES: Hypogonadism in men is related to the deterioration of general health. However, the association between lipid overaccumulation and ageing-related hypogonadism remains an undetermined concept. We aimed to provide an insight into the possible links between the lipid accumulation product (LAP) and late-onset hypogonadism (LOH). SETTING: Sun Yat-sen Memorial Hospital of Sun Yat-sen University. PARTICIPANTS: We included a population sample of 997 subjects aged 40 years or older. PRIMARY AND SECONDARY OUTCOME MEASURES: The LAP was calculated by gender-specific equations using waist circumference (WC) and triglyceride (TG). LOH was defined by the presence of androgen deficiency symptoms and low serum total testosterone levels. RESULTS: The prevalence of LOH was 9.4% in this population and gradually increased according to increasing LAP quartiles. Compared with subjects without LOH, ageing men with LOH had higher body mass index, WC, systolic blood pressure, percentage of subjects currently smoking, TG and follicle stimulating hormone and lower low-density lipoprotein cholesterol and sex hormone binding globulin. In multivariate logistic regression analysis, the adjusted ORs of LOH for increasing LAP quartiles 1-4 were 1.00 (reference), 1.10 (95% CI 0.45-2.69), 2.15 (95% CI 0.93-4.94) and 3.83 (95% CI 1.73-8.45), respectively. CONCLUSION: Body lipid accumulation evaluated by the LAP is independently associated with the prevalence of LOH in middle-aged and elderly Chinese men.

Endothelial cell-derived small extracellular vesicles suppress cutaneous wound healing through regulating fibroblasts autophagy.

Diabetic foot ulcer is a life-threatening clinical problem in diabetic patients. Endothelial cell-derived small extracellular vesicles (sEVs) are important mediators of intercellular communication in the pathogenesis of several diseases. However, the exact mechanisms of wound healing mediated by endothelial cell-derived sEVs remain unclear. sEVs were isolated from human umbilical vein endothelial cells (HUVECs) pretreated with or without advanced glycation end products (AGEs). The roles of HUVEC-derived sEVs on the biological characteristics of skin fibroblasts were investigated both in vitro and in vivo We demonstrate that sEVs derived from AGEs-pretreated HUVECs (AGEs-sEVs) could inhibit collagen synthesis by activating autophagy of human skin fibroblasts. Additionally, treatment with AGEs-sEVs could delay the wound healing process in Sprague-Dawley (SD) rats. Further analysis indicated that miR-106b-5p was up-regulated in AGEs-sEVs and importantly, in exudate-derived sEVs from patients with diabetic foot ulcer. Consequently, sEV-mediated uptake of miR-106b-5p in recipient fibroblasts reduces expression of extracellular signal-regulated kinase 1/2 (ERK1/2), resulting in fibroblasts autophagy activation and subsequent collagen degradation. Collectively, our data demonstrate that miR-106b-5p could be enriched in AGEs-sEVs, then decreases collagen synthesis and delays cutaneous wound healing by triggering fibroblasts autophagy through reducing ERK1/2 expression.

Human tissue inhibitor of metalloproteinases-1 improved wound healing in diabetes through its anti-apoptotic effect.

Impaired wound healing accompanies severe cell apoptosis in diabetic patients. Tissue inhibitor of metalloproteinases-1 (TIMP-1) was known to have effects on promoting growth and anti-apoptosis for cells. We aimed to determine the actual levels of TIMP-1 and cell apoptosis in: (i) the biopsies of diabetic and non-diabetic foot tissue and (ii) the human fibroblasts with or without treatments of advanced glycation end-products (AGEs). Next, we aimed to determine the improved levels of cell apoptosis and wound healing after the treatments of either active protein of TIMP-1 or in vivo expression of gene therapy vector-mediated TIMP-1 in both the human fibroblasts and the animal model of diabetic rats. The levels of TIMP-1 were significantly reduced in diabetic skin tissues and in AGEs-treated fibroblasts. Both AGEs-treated cells were effectively protected from apoptosis by active protein of TIMP-1 at appropriate dose level. So did the induced in vivo TIMP-1 expression after gene delivery. Similar effects were also found on the significant improvement of impaired wound healing in diabetic rats. We concluded that TIMP-1 improved wound healing through its anti-apoptotic effect. Treatments with either active protein TIMP-1 or TIMP-1 gene therapy delivered in local wound sites may be used as a strategy for accelerating diabetic wound healing.

Efficiency and Safety of ß-CD-(D3)7 as siRNA Carrier for Decreasing Matrix Metalloproteinase-9 Expression and Improving Wound Healing in Diabetic Rats.

Overexpression of matrix metalloproteinase-9 (MMP-9) is critical for diabetic chronic wounds involved in the refractory wound healing process. We aimed to develop a strategy through RNAi to decrease MMP-9 expression and improve diabetic wound healing. We had explored ß-CD-(D3)7 as a gene carrier to take siRNA and effectively interfere with MMP-9 expression. It has been proven that ß-CD-(D3)7 could be used as an effective siRNA delivery system. In this study, we want to know about the efficiency and safety of ß-CD-(D3)7/MMP-9 siRNA for improving wound healing in diabetic rats. ß-CD-(D3)7/MMP-9 siRNA treated animals show lower levels of MMP-9 expression, which induce faster wound-close rates. Histological evaluation indicates that ß-CD-(D3)7/MMP-9 siRNA significantly increases the content of collagen around the injured tissues. The number of neutrophilic ganulocytes was significantly decreased through treatment of ß-CD-(D3)7/MMP-9 siRNA. In vivo fluorescence imaging assessment shows that ß-CD-(D3)7/MMP-9 siRNA could not cause organ damage and organ accumulation. The results suggest that ß-CD-(D3)7/MMP-9 siRNA might be developed as a novel topical agent for the diabetic wounds treatment.

Comparison of the cellular transport mechanism of cationic, star-shaped polymers and liposomes in HaCat cells.

Several biological barriers must be overcome to achieve efficient nonviral gene delivery. These barriers include target cell uptake, lysosomal degradation, and dissociation from the carrier. In this study, we compared the differences in the uptake mechanism of cationic, star-shaped polymer/MMP-9siRNA complexes (ß-CD-(D3)7/MMP-9siRNA complexes: polyplexes) and commercial liposome/MMP-9siRNA complexes (Lipofectamine® 2000/MMP-9siRNA complexes: liposomes). The uptake pathway and transfection efficiency of the polyplexes and liposomes were determined by fluorescence microscopy, flow cytometry, and reverse transcriptase-polymerase chain reaction. The occurrence of intracellular processing was assessed by confocal laser scanning microscopy. Endosomal acidification inhibitors were used to explore the endosomal escape mechanisms of the polyplexes and lysosomes. We concluded that the polyplexes were internalized by non-caveolae- and non-clathrin-mediated pathways, with no lysosomal trafficking, thereby inducing successful transfection, while the majority of liposomes were internalized by clathrin-dependent endocytosis (CDE), caveolae-mediated endocytosis, and macropinocytosis, and only CDE induced successful transfection. Liposomes might escape more quickly than polyplexes, and the digestion effect of acidic organelles on liposomes was faint compared to the polyplexes, although both complexes escaped from endolysosomes via the proton sponge mechanism. This may be the key aspect that leads to the lower transfection efficiency of the ß-CD-(D3)7/MMP-9siRNA complexes. The present study may offer some insights for the rational design of novel delivery systems with increased transfection efficiency but decreased toxicity.

AGE-induced keratinocyte MMP-9 expression is linked to TET2-mediated CpG demethylation.

Studies have documented that unusually high expression of matrix metalloproteinase-9 (MMP-9) suppresses wound healing during the late stages of diabetic foot ulcers. Recently, it has been reported that the presence of advanced glycation end products-bovine serum albumin (AGE-BSA) resulted in a higher expression of MMP-9 in skin primary keratinocytes. The aim of the present study was to elucidate the molecular machinery that is responsible for the inappropriately high AGE-BSA-induced expression of MMP-9. It has been demonstrated that site-specific DNA demethylation played an important role in MMP-9 expression in AGE-BSA-stimulated keratinocytes. Ten-eleven translocation-2 (TET2) was up-regulated, whereas the percentage of methylation in the MMP-9 promoter was reduced. Furthermore, TET2 directly bound to a fragment surrounding the transcriptional start site in the MMP-9 promoter region, contributing to the regulation of MMP-9 expression. In addition, evidence indicated that TET2 affected the migration and proliferation in vitro of cultured skin primary keratinocytes. These findings indicated that TET2 directly interacted with the promoter region of MMP-9 in diabetic tissues and may be a novel master regulator of wound healing.

AGEs trigger autophagy in diabetic skin tissues and fibroblasts.

OBJECTIVE: Accumulation of advanced glycation end products (AGEs) contributes to the development of diabetic ulcers. Recent evidence indicates that AGEs administration enhanced autophagy in many cell types. As a positive trigger of autophagy, the effect of AGEs on autophagy in skin tissues and fibroblasts remains unknown. METHODS: Skin tissues were isolated from Spreqne-Dawley rats and immunohistochemical staining was performed to analyze the location of LC3 and FOXO1 in skin tissues. Then primary cultured foreskin fibroblast cells with treated with AGEs and the effect of AGEs on autophagy was investigated. Protein level expressions of LC3, Beclin-1 and FOXO1 in fibroblasts were analyzed by Western blotting. Autophagic flux is detected with autophagy inhibitor chloroquine and mRFP-GFP-LC3 tandem construct. RESULTS: Compared with skin from normal rats, immunohistochemical staining shows a predominant LC3 localization in fibroblasts cytoplasm in diabetic rats. Elevated expression of FOXO1 also existed in diabetic rats dermis fibroblasts when compared with normal rats in immunohistochemical analysis. In human skin fibroblasts cells, AGEs administration stimulated the autophagy related LC3-II/LC3-I and Beclin-1 expressions and increased autophagy flux. In mRFP-GFP-LC3 puncta formation assays, both autolysosome and autophagosome were increased in human fibroblasts after treatment with AGEs. Fibroblasts exposed to AGEs also have increased FOXO1 expression compared with control group. CONCLUSION: AGEs could induce autophagy at least in part via regulating the FOXO1 activity in diabetic skin tissues and fibroblasts.

Insulin-producing cells from embryonic stem cells rescues hyperglycemia via intra-spleen migration.

Implantation of embryonic stem cells (ESC)-derived insulin-producing cells has been extensively investigated for treatment of diabetes in animal models. However, the in vivo behavior and migration of transplanted cells in diabetic models remains unclear. Here we investigated the location and migration of insulin-producing cells labeled with superparamagnetic iron oxide (SPIO) using a dynamic MRI tracking method. SPIO labeled cells showed hypointense signal under the kidney subcapsules of diabetic mice on MRI, and faded gradually over the visiting time. However, new hypointense signal appeared in the spleen 1 week after transplantation, and became obvious with the time prolongation. Further histological examination proved the immigrated cells were insulin and C-peptide positive cells which were evenly distributed throughout the spleen. These intra-spleen insulin-producing cells maintained their protective effects against hyperglycemia in vivo, and these effects were reversed upon spleen removal. Transplantation of insulin-producing cells through spleen acquired an earlier blood glucose control as compared with that through kidney subcapsules. In summary, our data demonstrate that insulin-producing cells transplanted through kidney subcapsules were not located in situ but migrated into spleen, and rescues hyperglycemia in diabetic models. MRI may provide a novel tracking method for preclinical cell transplantation therapy of diabetes continuously and non-invasively.

Role of site-specific DNA demethylation in TNFα-induced MMP9 expression in keratinocytes.

Inappropriately high expression of matrix metalloproteinase 9 (MMP9) in the late stage of diabetic foot ulcers suppresses wound healing. The underlying mechanisms are not completely understood. Site-specific demethylation was reported to function in the regulation of genes, causing persistent high expression of target genes. Therefore, this study was designed to determine whether site-specific DNA demethylation was a key regulatory component of MMP9 expression in diabetic wound healing, and to further verify the crucial CpG site(s). Human keratinocyte cell line (HaCaT) cells were exposed to tumor necrosis factor a (TNFα), and changes in MMP9 expression and DNA methylation status were detected. We found TNFα treatment increased endogenous MMP9 expression in HaCaT cells and decreased the DNA methylation percentage at the -36 bp promoter site in a time-dependent manner. Bisulfite sequencing PCR revealed differentially demethylated CpG sites in the human MMP9 promoter region, but only the change at the -36 bp site was statistically significant. Dual-luciferase reporter assays showed that the promoter with only the -36 bp site demethylated had slightly higher transcriptional activity than the promoter with all other sites except the -36 bp site demethylated. Our results demonstrate that site-specific DNA demethylation plays an important role in MMP9 expression in TNFα-stimulated keratinocytes. The -36 bp site in the MMP9 gene promoter is crucial to this effect, but other CpG sites may exert synergistic effects. Collectively, these data may contribute to the future development of novel therapeutic strategies to treat diabetic foot ulcers and prevent gangrene and amputation.

Controlled release of epidermal growth factor from hydrogels accelerates wound healing in diabetic rats.

BACKGROUND: We sought to develop new recombinant human epidermal growth factor (rhEGF)-containing hydrogels and to investigate their biological activity and therapeutic effects on wound healing in diabetic rats. METHODS: Levels of rhEGF released from hydrogels were measured by enzyme-linked immunosorbent assay. The cellular proliferating activity of released rhEGF was evaluated by MTT assay. Fifty-six wounded diabetic rats were randomly divided into four groups with different topical treatment daily. The therapeutic effects were evaluated by wound area measurement, histologic analysis, immunohistochemical assessment of proliferating cell nuclear antigen and B-cell lymphoma/leukemia-2, and Western blotting of EGF receptor. RESULTS: The rhEGF released from the hydrogel matrix kept its bioactivity on stimulating proliferation of the BALB/c3T3 cell line. Wound closure rates on postoperative day 14 were 75.8% in the negative control group, 82.83% in the group treated with hydrogel matrix, 85.87% in the group treated with rhEGF-containing hydrogel, and 81.18% in the group treated with rhEGF solution. Compared with hydrogel matrix, rhEGF-containing hydrogel had an additional effect on induction of EGF receptor expression (P < .05). Compared with negative controls, protein expression of B-cell lymphoma/leukemia-2 was higher in the rhEGF-containing groups (P < .05). Proliferating cell nuclear antigen was induced at its highest level on day 7 in the rhEGF-containing hydrogel-treated group (P < .05). CONCLUSIONS: These data from in vitro release and diabetic animal models highlight the efficacy of hydrogels as a controlled releasing system for topical application of EGFs. The rhEGF-containing hydrogel we developed holds the merits of prolonged and sustained releasing of bioactive rhEGF and therapeutic potential in enhancing diabetic wound healing.