Topical application of metformin accelerates cutaneous wound healing in streptozotocin-induced diabetic rats

BACKGROUND

Diabetic chronic wound, which is one of the diabetic complications caused by hyperglycemia, characterized by prolonged inflammation has become one of the most serious challenges in the clinic. Hyperglycemia during diabetes not only causes prolonged inflammation and delayed wound healing but also modulates the activation of nuclear factor-kappa B (NF-κB) and the expression of matrix metalloproteinases (MMPs). Although metformin is the oldest oral antihyperglycemic drug commonly used for treating type 2 diabetes, few studies have explored the molecular mechanism of its topical effect on wound healing. Therefore, we aimed to investigate the molecular effects of topical metformin application on delayed wound healing, which's common in diabetes.

METHODS AND RESULTS

In this context, we created a full-thickness excisional wound model in Wistar albino rats and, investigated NF-κB p65 DNA-binding activity and expression levels of RELA (p65), MMP2 and MMP9 in wound samples taken on days 0, 3, 7, and 14 from diabetic/non-diabetic rats treated with metformin and saline. As a result of our study, we showed that topically applied metformin accelerates wound healing by suppressing NF-κB p65 activity and diminishing the expression of MMP2 and MMP9.

CONCLUSIONS

Diabetic wounds treated with metformin healed even faster than those in the control group that mimicked standard wound healing.

A molecular approach to maggot debridement therapy with Lucilia sericata and its excretions/secretions in wound healing

Chronic wounds caused by underlying physiological causes such as diabetic wounds, pressure ulcers, venous leg ulcers and infected wounds affect a significant portion of the population. In order to treat chronic wounds, a strong debridement, removal of necrotic tissue, elimination of infection and stimulation of granulation tissue are required. Maggot debridement therapy (MDT), which is an alternative treatment method based on history, has been used quite widely. MDT is an efficient, simple, cost-effective and reliable biosurgery method using mostly larvae of Lucilia sericata fly species. Larvae can both physically remove necrotic tissue from the wound site and stimulate wound healing by activating molecular processes in the wound area through the enzymes they secrete. The larvae can stimulate wound healing by activating molecular processes in the wound area through enzymes in their excretions/secretions (ES). Studies have shown that ES has antibacterial, antifungal, anti-inflammatory, angiogenic, proliferative, hemostatic and tissue-regenerating effects both in vivo and in vitro. It is suggested that these effects stimulate wound healing and accelerate wound healing by initiating a direct signal cascade with cells in the wound area. However, the enzymes and peptides in ES are mostly still undefined. Examining the molecular content of ES and the biological effects of these ingredients is quite important to illuminate the molecular mechanism underlying MDT. More importantly, ES has the potential to have positive effects on wound healing and to be used more as a therapeutic agent in the future, so it can be applied as an alternative to MDT in wound healing.

Regulation of MMP 2 and MMP 9 expressions modulated by AP-1 (c-jun) in wound healing: improving role of Lucilia sericata in diabetic rats

AIMS

Lucilia sericata larvae have been successfully used on healing of wounds in the diabetics. However, the involvement of the extraction/secretion (ES) products of larvae in the treatment of diabetic wounds is still unknown. Activator protein-1 (AP-1) transcription, composed of c-jun and c-Fos proteins, has been shown to be the principal regulator of multiple MMP transcriptions under a variety of conditions, also in diabetic wounds. Specifically, MMP-2 and MMP-9's transcriptions are known to be modulated by AP-1. c-jun has been demonstrated to be a repressor of p53 in immortalized fibroblasts. The aim of the present study is to investigate the effects of L. sericata ES on the expression of AP-1 (c-jun), p53, MMP-2, and MMP-9 in wound biopsies dissected from streptozotocin induced diabetic rats.

METHODS

The expression levels of MMP-2, MMP-9, c-jun and p53 in dermal tissues were determined at days 0, 3, 7 and 14 after wounding, using immunohistochemical analysis and quantitative real-time PCR.

RESULTS

The treatment with ES significantly decreased through inflammation-based induction of MMP-2 and MMP-9 expression levels in the wounds of diabetic groups, compared to control groups at the third day of wound healing. At the 14th day, there were dramatic decreases in expression of c-jun, MMP-9, and p53 in ES-treated groups, compared to the diabetic group (P < 0.001, P < 0.05 and P < 0.01, respectively).

CONCLUSION

ES products of L. sericata may enhance the process of wound healing in phases of inflammation, proliferation, and re-epithelization, essentially via regulating c-jun expression and modulating MMP-2 and MMP-9 expressions.

Effects of Lucilia sericata on wound healing in streptozotocin-induced diabetic rats and analysis of its secretome at the proteome level

The use of Lucilia sericata larvae on the healing of wounds in diabetics has been reported. However, the role of the excretion/secretion (ES) products of the larvae in treatment of diabetic wounds remains unknown. This study investigated whether application of the ES products of L. sericata on the wound surface could improve the impaired wound healing in streptozotocin-induced diabetic rats. Additional analysis was performed to understand proteome content of L. sericata secretome to understand ES contribution at the molecular level. For this purpose, full-thickness skin wounds were created on the backs of diabetic and control rats. A study was conducted to assess the levels of the ES-induced collagen I/III expression and to assay nuclear factor κB (NF-κB) (p65) activity in wound biopsies and ES-treated wounds of diabetic rat skin in comparison to the controls. The expression levels of collagen I/III and NF-κB (p65) activity were determined at days 3, 7, and 14 after wounding using immunohistological analyses and enzyme-linked immunosorbent assay technique. The results indicated that treatment with the ES extract increased collagen I expressions of the wound control and diabetic tissue. But the increase in collagen I expression in the controls was higher than the one in the diabetics. NF-κB (p65) activity was also increased in diabetic wounds compared to the controls, whereas it was decreased in third and seventh days upon ES treatment. The results indicated that ES products of L. sericata may enhance the process of wound healing by influencing phases such as inflammation, NF-κB (p65) activity, collagen synthesis, and wound contraction. These findings may provide new insights into understanding of therapeutic potential of ES in wound healing in diabetics.

DNA repair gene XRCC1 polymorphisms and the risk of asthma in a Turkish population

Polymorphisms have been identified in several DNA damage repair genes. These polymorphisms may effect DNA repair capacity and modulate asthma susceptibility. In this study, we aimed to determine the two polymorphisms in DNA repair gene, x-ray repair cross-complementing group 1 (XRCC1), in a sample of Turkish patients with asthma, and evaluate their association with asthma development. We used polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) to analyze XRCC1 Arg194Trp and XRCC1 Arg399Gln polymorphisms in 116 patients with asthma and in 180 disease-free controls. Our data showed a positive association between the polymorphisms of codons 194 (odds ratio [OR] = 1.97, 95% confidence interval [CI] = 1.06-3.66, and p = 0.03 for Arg/Trp genotype) and 399 (OR = 1.87, 95% CI = 1.12-3.13, and p = 0.02 for Arg/Gln genotype, and OR = 2.59, 95% CI = 1.24-5.43, and p = 0.01 for Gln/Gln genotype) and asthma risk. No statistically significant difference was found for the allelic and genotypic distributions of the polymorphisms in XRCC1 gene between mild and moderate asthmatic patients. A combined analysis of the effect of XRCC1 codons 194 and 399 revealed the highest risk (OR = 4.17, 95% CI = 1.77-9.83, and p = 0.001) for carriers of the polymorphic alleles in both of these codons. These results suggest that the risk of asthma may be associated with DNA repair mechanisms, and understanding these mechanisms will help identify individuals at increased risk of developing asthma and should lead to improved treatment of asthma.

The Ala allele at Val762Ala polymorphism in poly(ADP-ribose) polymerase-1 (PARP-1) gene is associated with a decreased risk of asthma in a Turkish population

BACKGROUND AND OBJECTIVE

It has been suggested that inhibition of poly (ADP-ribose) polymerase-1 (PARP-1), either pharmacologically or by a gene knockout provides significant protection against systemic or tissue inflammation in animal models. The aim of this study was to analyze the association of the PARP-1 Val762Ala polymorphism, which has beenreported to be associated with decreased enzymatic activity, in Turkish patients with adult asthma.

METHODS

A total of 112 subjects with stable asthma and 180 normal controls from the same geographic region were studied and polymerase chain reaction-based restriction analysis was used to identify Val762Ala polymorphism of the PARP-1.

RESULTS

In univariate analysis, PARP-1 762 AA genotype conferred a 3.4 fold reduction in risk (OR = 0.297, 95% CI = 0.105-0.813; P = 0.014), while heterozygous VA genotype conferred an even greater level of protection (OR = 0.06; 95%CI, 0.026-0.14; P < 10(-6)). In addition, wild type PARP-1 762 V allele had 5 times the risk of developing asthma than those without the allele (OR 0.199, CI 0.118-0.334, P = 10(-6)).

CONCLUSIONS

These findings suggest that PARP-1 V762A variants may be one of the factors participating in protection or susceptibility to asthma in our population.