Exendin-4, a glucagon-like peptide-1 analogue, accelerates diabetic wound healing

Incretin-based therapy and the risk of diabetic foot ulcers and related events

AIM

To investigate the effect of dipeptidyl peptidase-4 inhibitors (DPP4-Is) and glucagon-like peptide-1 receptor agonists (GLP1-RAs) on diabetic foot ulcer (DFU) and DFU-related outcomes (lower limb amputation [LLA], DFU-related hospitalization and mortality).

METHODS

We performed a cohort study with data from the Clinical Practice Research Datalink Aurum database with linkage to hospital data. We included people with type 2 diabetes starting treatment with metformin. Then we propensity score matched new users of DPP4-Is and sulphonylureas (N = 98 770), and new users of GLP1-RAs and insulin (N = 25 422). Cox proportional hazards models estimated the hazard ratios (HRs) for the outcomes.

RESULTS

We observed a lower risk of DFU with both DPP4-I use versus sulphonylurea use (HR 0.88, 95% confidence interval [CI]: 0.79-0.97) and GLP1-RA use versus insulin use (HR 0.44, 95% CI: 0.32-0.60) for short-term exposure (≤ 400 days) and HR 0.74 (95% CI: 0.60-0.92) for long-term exposure (>400 days). Furthermore, the risks of hospitalization and mortality were lower with both DPP4-I use and GLP1-RA use. The risk of LLA was lower with GLP1-RA use. The results remained consistent across several sensitivity analyses.

CONCLUSIONS

Incretin-based therapy was associated with a lower risk of DFU and DFU-related outcomes. This suggests benefits for the use of this treatment in people at risk of DFU.

Recent advances in the adjunctive management of diabetic foot ulcer: Focus on noninvasive technologies

Diabetic foot ulcer (DFU) is one of the most costly and serious complications of diabetes. Treatment of DFU is usually challenging and new approaches are required to improve the therapeutic efficiencies. This review aims to update new and upcoming adjunctive therapies with noninvasive characterization for DFU, focusing on bioactive dressings, bioengineered tissues, mesenchymal stem cell (MSC) based therapy, platelet and cytokine-based therapy, topical oxygen therapy, and some repurposed drugs such as hypoglycemic agents, blood pressure medications, phenytoin, vitamins, and magnesium. Although the mentioned therapies may contribute to the improvement of DFU to a certain extent, most of the evidence come from clinical trials with small sample size and inconsistent selections of DFU patients. Further studies with high design quality and adequate sample sizes are necessitated. In addition, no single approach would completely correct the complex pathogenesis of DFU. Reasonable selection and combination of these techniques should be considered.

Morroniside promotes skin wound re-epithelialization by facilitating epidermal stem cell proliferation through GLP-1R-mediated upregulation of β-catenin expression

Epidermal stem cells (EpSCs) play a vital role in skin wound healing through re-epithelialization. Identifying chemicals that can promote EpSC proliferation is helpful for treating skin wounds. This study investigates the effect of morroniside on cutaneous wound healing in mice and explores the underlying mechanisms. Application of 10‒50 μg/mL of morroniside to the skin wound promotes wound healing in mice. In vitro studies demonstrate that morroniside stimulates the proliferation of mouse and human EpSCs in a time- and dose-dependent manner. Mechanistic studies reveal that morroniside promotes the proliferation of EpSCs by facilitating the cell cycle transition from the G1 to S phase. Morroniside increases the expression of β-catenin via the glucagon-like peptide-1 receptor (GLP-1R)-mediated PKA, PKA/PI3K/AKT and PKA/ERK signaling pathways, resulting in an increase in cyclin D1 and cyclin E1 expression, either directly or by upregulating c-Myc expression. This process ultimately leads to EpSC proliferation. Administration of morroniside to mouse skin wounds increases the phosphorylation of AKT and ERK, the expressions of β-catenin, c-Myc, cyclin D1, and cyclin E1, as well as the proliferation of EpSCs, in periwound skin tissue, and accelerates wound re-epithelialization. These effects of morroniside are mediated by the GLP-1R. Overall, these results indicate that morroniside promotes skin wound healing by stimulating the proliferation of EpSCs via increasing β-catenin expression and subsequently upregulating c-Myc, cyclin D1, and cyclin E1 expressions through GLP-1R signaling pathways. Morroniside has clinical potential for treating skin wounds.

Practice Patterns and Perspectives of the Off-Label Use of GLP-1 Agonists for Cosmetic Weight Loss

BACKGROUND

The off-label use of glucagon-like peptide 1 (GLP-1) agonists for cosmetic weight loss has captured the interest of the public. However, there is a paucity of published data on their utilization, implications, and management, particularly in the plastic surgery community.

OBJECTIVES

This study aims to explore the current practice patterns of aesthetic plastic surgeons regarding the off-label implementation of GLP-1 agonists.

METHODS

A 35-question survey was sent to the 2600 members of The Aesthetic Society in July 2023. The survey collected physician demographics, practice settings, patient population demographics, and the use and management of GLP-1 agonists in their practice. No identifying variables were collected; all responses were anonymous.

RESULTS

A total of 368 respondents were included. A quarter of respondents (25.3%) prescribed or utilized GLP-1 agonists in their practice. Nearly a third (29.9%) reported personal use of the medication, of which 71 (70.3%) indicated it was for cosmetic weight loss. Many aspects of the current treatment, counseling, and follow-up practices were similar among prescribing plastic surgeons. However, there were discrepancies in screening, nutrition counseling, and perioperative management. The majority believed that GLP-1 agonists were effective for weight loss (68.9%), profitable for business (57.8%), and would recommend its implementation to other plastic surgeons (68.5%).

CONCLUSIONS

As leaders in the aesthetic field, it behooves plastic surgeons to take charge of shaping public opinion surrounding the growing off-label use of GLP-1 agonists for cosmetic weight loss. Plastic surgeons' leadership is imperative in establishing safe and ethical guidelines and protocols for proper screening, management, and patient care.

LEVEL OF EVIDENCE: 4

The use of sodium-glucose co-transporter-2 inhibitors or glucagon-like peptide-1 receptor agonists versus sulfonylureas and the risk of lower limb amputations: a nation-wide cohort study

BACKGROUND

Numerous studies have investigated the potential association of sodium-glucose co-transporter-2 inhibitors (SGLT2-Is) with an increased risk of lower limb amputations (LLAs), but have produced conflicting results. Particularly studies comparing SGLT2-Is to glucagon-like peptide-1 receptor agonists (GLP1-RAs) seem to find a higher LLA risk with SGLT2-I use. This raises the question whether the results are driven by a protective GLP1-RA-effect rather than a harmful SGLT2-I-effect. GLP1-RAs could promote wound healing and therefore reduce the risk of LLAs, but the associations between both drug classes and LLA remain uncertain. Therefore, the aim of the current study was to investigate the risk of LLA and diabetic foot ulcer (DFU) with SGLT2-I use and GLP1-RA use versus sulfonylurea use.

METHODS

A retrospective population-based cohort study was conducted using data from the Danish National Health Service (2013-2018). The study population (N = 74,475) consisted of type 2 diabetes patients aged 18 + who received a first ever prescription of an SGLT2-I, GLP1-RA or sulfonylurea. The date of the first prescription defined the start of follow-up. Time-varying Cox proportional hazards models estimated the hazard ratios (HRs) of LLA and DFU with current SGLT2-I use and GLP1-RA use versus current SU use. The models were adjusted for age, sex, socio-economic variables, comorbidities and concomitant drug use.

RESULTS

Current SGLT2-I use was not associated with a higher risk of LLA versus sulfonylureas {adjusted HR 1.10 [95% confidence interval (CI) 0.71-1.70]}. Current GLP1-RA use, on the other hand, was associated with a lower risk of LLA [adjusted HR 0.57 (95%CI 0.39-0.84)] compared to sulfonylureas. The risk of DFU was similar to that with sulfonylureas with both exposures of interest.

CONCLUSION

SGLT2-I use was not associated with a higher risk of LLA, but GLP1-RAs with a lower risk of LLA. Previous studies reporting a higher risk of LLA with SGLT2-I use compared to GLP1-RA use might have been looking at a protective GLP1-RA effect, rather than a harmful SGLT2-I effect.

Effects of dulaglutide on endothelial progenitor cells and arterial elasticity in patients with type 2 diabetes mellitus

Background

Randomised controlled trial showed that dulaglutide can reduce the risk of atherosclerotic cardiovascular disease (ASCVD) in patients with type 2 diabetes mellitus (T2DM), but the underlying mechanisms remain unclear. This study aimed to investigate the effect of dulaglutide on the number and function of endothelial progenitor cells (EPCs) in the peripheral blood of patients with T2DM and its role in improving arterial elasticity, so as to determine potential mechanisms of preventive effect of dulaglutide on ASCVD.

Methods

Sixty patients with T2DM were treated with 1000 mg/day of metformin and randomly divided into two groups for 12 weeks: metformin monotherapy group (MET group, n = 30), and metformin combined with dulaglutide group (MET-DUL group, n = 30). Before and after treatment, the number of CD34⁺CD133⁺KDR⁺ EPCs and the brachial–ankle pulse wave velocity (baPWV) of the participants were measured, and EPC proliferation, adhesion, migration, and tubule formation were assessed in vitro.

Results

There were no significant differences in the number and function of EPCs and baPWV changes in MET group (P > 0.05). In MET-DUL group, nitric oxide (NO) levels and the number of EPCs increased after treatment (P < 0.05), while the levels of C-reactive protein (CRP), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), advanced glycation end products (AGEs), and baPWV decreased (P < 0.05). EPC proliferation, adhesion, migration, and tubule formation abilities were significantly enhanced (P < 0.05). Correlation analysis showed that in MET-DUL group, the changes in CRP, IL-6, TNF-α, and AGEs were negatively correlated with the number of EPCs and their proliferation and migration abilities (P < 0.05). Body weight, NO, CRP, and IL-6 levels were independent factors affecting the number of EPCs (P < 0.05). The changes in number of EPCs, proliferation and migration abilities of EPCs, and NO and IL-6 levels were independent influencing factors of baPWV changes (P < 0.05).

Conclusion

Dulaglutide can increase the number and function of EPCs in peripheral blood and improve arterial elasticity in patients with T2DM; it is accompanied by weight loss, inflammation reduction, and high NO levels. Dulaglutide regulation of EPCs may be a mechanism of cardiovascular protection.

Major adverse cardiovascular and limb events in patients with diabetes treated with GLP-1 receptor agonists vs DPP-4 inhibitors

AIMS/HYPOTHESIS

The safety and efficacy of glucagon-like peptide-1 receptor agonists (GLP1RAs) and dipeptidyl peptidase-4 inhibitors (DPP4is) in major cardiovascular adverse events were previously examined in cardiovascular outcome trials. However, the effects of these drugs on adverse limb outcomes were poorly examined. This study aimed to determine the real-world outcomes of patients with diabetes mellitus receiving GLP1RAs as compared with those receiving DPP4is in terms of major adverse cardiovascular and limb events.

METHODS

A retrospective cohort study was conducted with data collected by the Taiwan National Health Insurance database between 1 May 2011 and 31 December 2017. Patients who were treated for type 2 diabetes with a GLP1RA or DDP4i during this period (n = 1,080,993), were identified. The primary outcome was a composite of major adverse limb events, defined as peripheral artery disease (PAD), critical limb ischaemia, percutaneous transluminal angioplasty or peripheral bypass for PAD, and amputation. The secondary cardiovascular outcome was the composite of cardiovascular death, non-fatal myocardial infarction and non-fatal ischaemic stroke. Propensity-score matching (PSM) at a 1:3 ratio between GLP1RA and DPP4i groups was done to minimise possible selection bias.

RESULTS

A total of 948,342 individuals treated between 1 May 2011 and 31 December 2017, were identified, with 4460 in the GLP1RA group and 13,380 in the DPP4i group after PSM. The incidence of primary composite outcome events was significantly lower in those treated with GLP1RAs compared with those treated with DPP4is (2.59 vs 4.22 events per 1000 person-years; subdistribution HR [SHR] 0.63 [95% CI 0.41, 0.96]), primarily due to lower rates of amputation (1.29 events per 1000 person-years for GLP1RAs vs 2.4 events per 1000 person-years for DPP4is; SHR 0.55 [95% CI 0.30, 0.99]). Treatment with GLP1RAs was also associated with significantly lower risks of secondary composite outcome events (11.02 vs 17.95 events per 1000 person-years; HR 0.62 [95% CI 0.51, 0.76]). Moreover, the observed beneficial effects of GLP1RAs on reducing composite adverse limb outcomes were particularly noticeable in the non-cardiovascular patients and statin users (p for interaction <0.05).

CONCLUSIONS/INTERPRETATION

In individuals with diabetes, the use of GLP1RAs was associated with significantly lower risks of major adverse limb events when compared with the use of DPP4is. The reduction in risk was driven largely by reduced rate of amputations. Moreover, treatment with GLP1RAs was also associated with lower risks of cardiovascular death, non-fatal stroke, non-fatal myocardial infarction and death from any cause. However, some unexplored confounding factors may exist in this observation study and future large-scale randomised controlled trials are needed.

The glucagon-like peptide 1 receptor agonist Exendin-4 induces tenogenesis in human mesenchymal stem cells

Tendon injuries are common and account for up to 50% of musculoskeletal injuries in the United States. The poor healing nature of the tendon is attributed to poor vascularization and cellular composition. In the absence of FDA-approved growth factors for tendon repair, engineering strategies using bioactive factors, donor cells, and delivery matrices to promote tendon repair and regeneration are being explored. Growth factor alternatives in the form of small molecules, donor cells, and progenitors offer several advantages and enhance the tendon healing response. Small drug molecules and peptides offer stability over growth factors that are known to suffer from relatively short biological half-lives. The primary focus of this study was to assess the ability of the exendin-4 (Ex-4) peptide, a glucagon-like peptide 1 (GLP-1) receptor agonist, to induce tenocyte differentiation in bone marrow-derived human mesenchymal stem cells (hMSCs). We treated hMSCs with varied doses of Ex-4 in culture media to evaluate proliferation and tendonogenic differentiation. A 20 nM Ex-4 concentration was optimal for promoting cell proliferation and tendonogenic differentiation. Tendonogenic differentiation of hMSCs was evaluated via gene expression profile, immunofluorescence, and biochemical analyses. Collectively, the levels of tendon-related transcription factors (Mkx and Scx) and extracellular matrix (Col-I, Dcn, Bgn, and Tnc) genes and proteins were elevated compared to media without Ex-4 and other controls including insulin and IGF-1 treatments. The tendonogenic factor Ex-4 in conjunction with hMSCs appear to enhance tendon regeneration.

Exenatide improves random-pattern skin flap survival via TFE3 mediated autophagy augment

Random-pattern skin flaps are widely applied to rebuild and restore soft-tissue damage in reconstructive surgery; however, ischemia and subsequent ischemia-reperfusion injury lead to flap necrosis and are major complications. Exenatide, a glucagon-like peptide-1 analog, exerts therapeutic benefits for diabetic wounds, cardiac injury, and nonalcoholic fatty liver disease. Furthermore, Exenatide is a known activator of autophagy, which is a complex process of subcellular degradation that may enhance the viability of random skin flaps. In this study, we explored whether exenatide can improve skin flap survival. Our results showed that exenatide augments autophagy, increases flap viability, enhances angiogenesis, reduces oxidative stress, and alleviates pyroptosis. Coadministration of exenatide with 3-methyladenine and chloroquine, potent inhibitors of autophagy, reversed the beneficial effects, suggesting that the therapeutic benefits of exenatide for skin flaps are due largely to autophagy activation. Mechanistically, we identified that exenatide enhanced activation and nuclear translocation of TFE3, which leads to autophagy activation. Furthermore, we found that exenatide activates the AMPK-SKP2-CARM1 and AMPK-mTOR signaling pathways, which likely lead to exenatide's effects on activating TFE3. Overall, our findings suggest that exenatide may be a potent therapy to prevent flap necrosis, and we also reveal novel mechanistic insight into exenatide's effect on flap survival.

Exenatide inhibits necrosis by enhancing angiogenesis and ameliorating ischemia/reperfusion injury in a random skin flap rat model

BACKGROUND

Random skin flaps are often used for plastic repair because they are convenient and flexible. However, necrosis of flaps is a common complication that may lead to disastrous consequences. Exenatide, a glucagon-like peptide 1 receptor agonist, can enhance angiogenesis and ameliorate ischemia/reperfusion injury. Our experiments explored random skin flap outcomes after its use.

METHODS

We established modified dorsal McFarlane flaps on 54 Sprague-Dawley rats and divided the rats into three groups (control, Exe-I, and Exe-II). We intraperitoneally injected either 4 or 8 μg/kg/day exenatide into the rats of the Exe-I and Exe-II groups, respectively. On the seventh day after the operation, we measured the levels of superoxide dismutase (SOD) and malondialdehyde (MDA). Tissue sections were obtained for histopathological and immunohistochemical analyses, and we evaluated the expression of vascular endothelial growth factor (VEGF), interleukin (IL) 6, IL-1β, nuclear factor kappa beta (NF-κB), Toll-like receptor 4 (TLR4), and tumor necrosis factor α (TNF-α). We measured blood flow reconstruction and angiogenesis using laser Doppler blood flowmetry and lead oxide/gelatin angiography, respectively.

RESULTS

Exenatide increased the average survival area of the flap and improved microvascular density and blood flow intensity in a dose-dependent manner. Meanwhile, the SOD level was up-regulated and the MDA level down-regulated. Exenatide also enhanced the expression of VEGF and reduced the expression of inflammatory cytokines (IL-6, IL-1β, NF-κB, TLR4, and TNF-α), thereby promoting angiogenesis and inhibiting inflammation.

CONCLUSIONS

Exenatide potentially inhibits necrosis in our rat random skin flap model.

Discovery of a novel short peptide with efficacy in accelerating the healing of skin wounds

Despite extensive efforts to develop efficacious therapeutic approaches, the treatment of skin wounds remains a considerable clinical challenge. Existing remedies cannot sufficiently meet current needs, so the discovery of novel pro-healing agents is of growing importance. In the current research, we identified a novel short peptide (named RL-QN15, primary sequence 'QNSYADLWCQFHYMC') from Rana limnocharis skin secretions, which accelerated wound healing in mice. Exploration of the underlying mechanisms showed that RL-QN15 activated the MAPK and Smad signaling pathways, and selectively modulated the secretion of cytokines from macrophages. This resulted in the proliferation and migration of skin cells and dynamic regulation of TGF-β1 and TGF-β3 in wounds, which accelerated re-epithelialization and granulation tissue formation and thus skin regeneration. Moreover, RL-QN15 showed significant therapeutic potency against chronic wounds, skin fibrosis, and oral ulcers. Our results highlight frog skin secretions as a potential treasure trove of bioactive peptides with healing activity. The novel peptide (RL-QN15) identified in this research shows considerable capacity as a candidate for the development of novel pro-healing agents.

Gemigliptin Inhibits Interleukin-1β-Induced Endothelial-Mesenchymal Transition via Canonical-Bone Morphogenetic Protein Pathway

BACKGROUND

Endothelial-to-mesenchymal transition (EndMT) contributes to inflammatory conditions inducing conversion of endothelial cells (ECs) into activated fibroblasts, promoting fibrotic diseases. Pro-inflammatory cytokine is the most potent inducer of EndMT. We investigated inhibition of interleukin-1β (IL-1β)-induced EndMT by gemigliptin, a dipeptidyl peptidase-IV inhibitor.

METHODS

We exposed human umbilical vein endothelial cells (HUVECs) to 10 ng/mL IL-1β/20 μM gemigliptin and analyzed the expression of endothelial, smooth muscle, mesenchymal, and osteoblastic markers, bone morphogenetic protein (BMP), Smad, and non-Smad signaling pathway proteins.

RESULTS

Morphological changes showed gemigliptin blocked IL-1β-induced EndMT, upregulated EC markers, and downregulated smooth muscle and mesenchymal markers. IL-1β activation of HUVECs is initiated by the BMP/Smad and non-smad BMP signaling pathways. Gemigliptin inhibited IL-1β induction of BMP2 and 7, activin receptor type IA, BMP receptor type IA, and BMP receptor type II. Reversal of IL-1β-mediated inhibition of BMP-induced Smad1/5/8, Smad2, and Smad3 phosphorylation by gemigliptin suggests involvement of the Smad pathway in gemigliptin action. In the non-Smad BMP pathway, gemigliptin treatment significantly increased the deactivation of extracellular regulated protein kinase (ERK), p38, and JNK by IL-1β. Gemigliptin treatment suppressed BMP-2-induced expression of key osteoblastic markers including osterix, runt-related transcription factor 2, and hepcidin during IL-1β-induced EndMT.

CONCLUSION

We demonstrated a novel protective mechanism of gemigliptin against fibrosis by suppressing IL-1β-induced EndMT.

The Treatment of Impaired Wound Healing in Diabetes: Looking among Old Drugs

Chronic wounds often occur in patients with diabetes mellitus due to the impairment of wound healing. This has negative consequences for both the patient and the medical system and considering the growing prevalence of diabetes, it will be a significant medical, social, and economic burden in the near future. Hence, the need for therapeutic alternatives to the current available treatments that, although various, do not guarantee a rapid and definite reparative process, appears necessary. We here analyzed current treatments for wound healing, but mainly focused the attention on few classes of drugs that are already in the market with different indications, but that have shown in preclinical and few clinical trials the potentiality to be used in the treatment of impaired wound healing. In particular, repurposing of the antiglycemic agents dipeptidylpeptidase 4 (DPP4) inhibitors and metformin, but also, statins and phenyotin have been analyzed. All show encouraging results in the treatment of chronic wounds, but additional, well designed studies are needed to allow these drugs access to the clinics in the therapy of impaired wound healing.

Activation of Angiogenesis and Wound Healing in Diabetic Mice Using NO-Delivery Dinitrosyl Iron Complexes

In diabetes, abnormal angiogenesis due to hyperglycemia and endothelial dysfunction impairs wound healing and results in high risks of diabetic foot ulcers and mortality. Alternative therapeutic methods were attempted to prevent diabetic complications through the activation of endothelial nitric oxide synthase. In this study, direct application of nitric oxide using dinitrosyl iron complexes (DNICs) to promote angiogenesis and wound healing under physiological conditions and in diabetic mice is investigated. Based on in vitro and in vivo studies, DNIC [Fe₂(μ-SCH₂CH₂OH)₂(NO)₄] (DNIC-1) with a sustainable NO-release reactivity (t_1/2 = 27.4 ± 0.5 h at 25 °C and 16.8 ± 1.8 h at 37 °C) activates the NO-sGC-cGMP pathway and displays the best pro-angiogenesis activity overwhelming other NO donors and the vascular endothelial growth factor. Moreover, this pro-angiogenesis effect of DNIC-1 restores the impaired angiogenesis in the ischemic hind limb and accelerates the recovery rate of wound closure in diabetic mice. This study translates synthetic DNIC-1 into a novel therapeutic agent for the treatment of diabetes and highlights its sustainable ^•NO-release reactivity on the activation of angiogenesis and wound healing.

Advancing pharmacotherapy for diabetic foot ulcers

INTRODUCTION

Standard treatment for diabetic foot ulcers (DFUs) includes off-loading, debridement, moisture balance, management of infection and peripheral arterial disease (PAD) as well as adequate glycemic control. The outcomes so far are unsatisfactory.

AREAS COVERED

Herein, the authors provide an outline of newer pharmacological agents for the management of DFUs and give their expert perspectives on future treatment strategies.

EXPERT OPINION

Evidence-based healthcare calls for high quality evidence from large RCTs before the implementation of new guidelines for the management of DFUs. Empagliflozin and liraglutide can be recommended for glucose control in patients with DFUs and PAD, while intensive lipid lowering therapy with evolocumab when primary cholesterol goals are not met could be offered to patients with DFUs. Further clinical studies are warranted to develop a structured algorithm for the treatment of DFUs that fail to heal after four weeks of current standard of care. Sucrose octasulfate dressings, becaplermin gel, and platelet-rich plasma (PRP) could also be considered as advanced treatment options for the management of hard to heal DFUs.

Propolis as an Adjuvant in the Healing of Human Diabetic Foot Wounds Receiving Care in the Diagnostic and Treatment Centre from the Regional Hospital of Talca

OBJECTIVE

Diabetic foot wounds are a relevant diabetes complication and a major health problem. It has been described that propolis has health benefits due to its anti-inflammatory, antioxidant, and support in the healing process. The current study assessed the effect of propolis as an adjuvant in the healing of human diabetic foot ulcers. This was evaluated in a randomized placebo-controlled study of subjects receiving care in the Diagnostic and Treatment Centre from the Regional Hospital of Talca, Chile.

RESEARCH DESIGN AND METHODS

Randomized subjects received ambulatory healing treatment for diabetes foot wounds with propolis spray (3%), which was applied to cover the entire wound surface each time it was dressed from week 0 until cicatrization or 8 weeks as a maximum. Two serum samples were taken (day 0 and end of the study) for cytokine and oxidative stress analyses. Also, macro- and microscopy were analyzed in the process of wound healing.

RESULTS

The study comprised 31 subjects with type 2 diabetes in treatment for diabetic foot wounds in the Diagnostic and Treatment Centre from the Regional Hospital of Talca. Propolis promotes a reduction of the wound's area by an average of 4 cm², related to an increase in the connective tissue deposit compared to the control. Also, propolis increased the glutathione (GSH) and GSH/glutathione disulfide (GSSG) ratio (p < 0.02), depleted tumor necrosis factor- (TNF-) α, and increased interleukin- (IL-) 10 levels. Topical propolis did not modify the biochemical parameters in the serum of the studied subjects.

CONCLUSIONS

The topical use of propolis turned out to be an interesting therapeutic strategy as an adjuvant in the care of diabetes foot wounds due to its ability to improve and promote healing based on its anti-inflammatory and antioxidant profile. This trial is registered with NCT03649243.

Incretin-based therapy for diabetic ulcers: from bench to bedside

INTRODUCTION

Diabetic foot ulcers are a serious complication of diabetes and are associated with pain, disability, and poor quality of life. Incretin-based therapy is available for type-2 diabetes. Aside from glucose control, such treatment can impart numerous beneficial effects.

AREAS COVERED

This review summarizes the preclinical and clinical evidence supporting incretin-based treatment approaches for diabetic ulcers.

EXPERT OPINION

Incretin-based therapy may have a role in the treatment of diabetic foot ulcers; the benefits of such treatment arise from attenuation of inflammatory response, improvement of keratinocyte migration, induction of angiogenesis, and the enhancement of tissue remodeling. Large-scale clinical trials are required to determine the advantages of GLP-1 receptor agonists and DPP4 inhibitors. Future research on the topical application of incretin-based therapy is necessary. Such therapeutic approaches may provide new hope in improving the treatment of impaired diabetic foot ulcers.

Anti-inflammatory and pro-healing impacts of exendin-4 treatment in Zucker diabetic rats: Effects on skin wound fibroblasts

Using male Zucker diabetic fatty (ZDF) rats implanted subcutaneously with polyethylene mesh pieces stimulating granulation tissue development, we investigated the effects of the in vivo and in vitro treatment with exendin-4, a glucagon-like peptide-1 agonist displaying a variety of antidiabetic actions, on the markers of metabolism, inflammation, and healing in addition to skin wound fibroblast/myofibroblast activities. Exendin-4 at increasing doses of 3-10 μg/kg or 0.9% saline was injected daily to ZDF rats pre-implanted with the mesh for 3 weeks. Then, fibroblasts/myofibroblasts isolated from the granulation tissue in both groups were further exposed in vitro to exendin-4 at concentrations of 0-100 nmol/l. After a 3-week administration period, cumulative food and water intake and body weight were reduced significantly. The serum and fibroblast culture medium C-reactive protein (CRP) concentrations and matrix metalloprotease-9/tissue matrix metalloproteinase inhibitor-1 (MMP-9/TIMP-1) ratio in the fibroblast culture medium were diminished significantly in the exendin-4 pretreated group, indicating the increased expression of anti-inflammatory and pro-healing biomarkers. In vivo exendin-4 treatment also increased the number of living fibroblasts/myofibroblasts in cell cultures. The subsequent in vitro exposure to exendin-4 significantly increased metabolic activity and total collagen content in fibroblast/myofibroblast colonies derived from exendin-4-pretreated rats but reduced the number of viable cells. A cytotoxic effect was noted at the highest exendin-4 concentrations used. To conclude, the treatment of diabetic rats with exendin-4 had beneficial effects on systemic and tissue metabolic, inflammatory, and healing markers and on fibroblast functions crucial for wound repair but showed some cytotoxicity on these cells.

The Impact of Liraglutide on Diabetes-Related Foot Ulceration and Associated Complications in Patients With Type 2 Diabetes at High Risk for Cardiovascular Events: Results From the LEADER Trial

OBJECTIVE

Diabetes-related foot ulcers (DFUs) and their sequelae result in large patient and societal burdens. Long-term data determining the efficacy of individual glucose-lowering agents on DFUs are lacking. Using existing data from the Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results (LEADER) trial, we conducted post hoc analyses assessing the impact of liraglutide versus placebo in people with type 2 diabetes and at high risk of cardiovascular (CV) events on the incidence of DFUs and their sequelae.

RESEARCH DESIGN AND METHODS

The LEADER trial (NCT01179048) was a randomized, double-blind, multicenter, CV outcomes trial assessing liraglutide (1.8 mg/day) versus placebo, in addition to standard of care, for up to 5 years. Information on DFUs was collected systematically during the trial, and DFU complications were assessed post hoc through reviewing case narratives.

RESULTS

During a median of 3.8 years' follow-up, similar proportions of patients reported at least one episode of DFU in the liraglutide and placebo groups (3.8% [176/4,668] versus 4.1% [191/4,672], respectively; hazard ratio [HR] 0.92 [95% CI 0.75, 1.13; P = 0.41]). Analysis of DFU-related complications demonstrated a significant reduction in amputations with liraglutide versus placebo (HR 0.65 [95% CI 0.45, 0.95; P = 0.03]). However, no differences were found for foot infections, involvement of underlying structures, or peripheral revascularization in the main analysis.

CONCLUSIONS

Treatment with liraglutide in patients with type 2 diabetes and at high risk of CV events in the LEADER trial did not increase the risk of DFU events and was associated with a significantly lower risk of DFU-related amputations compared with placebo. This association, possibly due to chance, needs further investigation.

Exogenous SERP1 attenuates restenosis by restoring GLP-1 receptor activity in diabetic rats following vascular injury

The activity of glucagon-like peptide 1 (GLP-1R) is essential for preventing restenosis following vascular injury; however, the mechanism of dysfunctional GLP-1R glycosylation and ways to enhance the activity of GLP-1R on vascular surfaces in diabetic patients are poorly understood. In the present study, we investigated the N-glycosylation level and role of stress-associated endoplasmic reticulum protein 1 (SERP1) in preventing restenosis following carotid injury in diabetic rats. Our results showed that N-glycosylation levels in both rat aortic endothelial cells (RAOECs) and rat vascular smooth muscle cells (VSMCs) decreased gradually following glucose treatment in a concentration dependant manner. Furthermore, co-immunoprecipitation (Co-IP) analyses indicated that SERP1 could interact with GLP-1R in RAOECs and VSMCs. Moreover, SERP1 enhanced GLP-1R N-glycosylation and increased the production of phosphorylated endothelial nitric oxide synthase (eNOS) as well as proliferation of RAOECs. SERP1 also increased phosphorylated adenosine monophosphate activated protein kinase (AMPK) and decreased the migration of VSMCs. Importantly, intima media thickness (IMT) and neointimal hyperplasia were alleviated in the carotid artery of diabetic rats injected with SERP1 following balloon injury. We also found an increase in re-endothelialization and a decrease in VSMC proliferation in the carotid artery of diabetic rats injected with SERP1. In summary, the remarkable effects of SERP1 on reducing restenosis following vascular injury may contribute to future advancements in the treatment of diabetic vascular complications.

Novel skeletal effects of glucagon-like peptide-1 (GLP-1) receptor agonists

Type 2 diabetes mellitus (T2DM) leads to bone fragility and predisposes to increased risk of fracture, poor bone healing and other skeletal complications. In addition, some anti-diabetic therapies for T2DM can have notable detrimental skeletal effects. Thus, an appropriate therapeutic strategy for T2DM should not only be effective in re-establishing good glycaemic control but also in minimising skeletal complications. There is increasing evidence that glucagon-like peptide-1 receptor agonists (GLP-1RAs), now greatly prescribed for the treatment of T2DM, have beneficial skeletal effects although the underlying mechanisms are not completely understood. This review provides an overview of the direct and indirect effects of GLP-1RAs on bone physiology, focusing on bone quality and novel mechanisms of action on the vasculature and hormonal regulation. The overall experimental studies indicate significant positive skeletal effects of GLP-1RAs on bone quality and strength although their mechanisms of actions may differ according to various GLP-1RAs and clinical studies supporting their bone protective effects are still lacking. The possibility that GLP-1RAs could improve blood supply to bone, which is essential for skeletal health, is of major interest and suggests that GLP-1 anti-diabetic therapy could benefit the rising number of elderly T2DM patients with osteoporosis and high fracture risk.

Exendin-4, a glucagon-like peptide-1 analogue accelerates healing of chronic gastric ulcer in diabetic rats

Background

Diabetes mellitus is an independent risk factor for impaired healing of peptic ulcers, and there are currently no supplementary therapeutics other than the standard antipeptic medicine to improve the ulcer healing in diabetes. This study examined the potential pleiotropic effect of a glucagon-like peptide (Glp)-1 analogue exendin (Ex)-4 on the regeneration of gastric ulcer in streptozotocin-induced diabetic rats.

Methods and results

Chronic ulcer was created in rat stomach by submucosal injection of acetic acid and peri-ulcer tissues were analyzed 7 days after operation. Ulcer wound healing was impaired in diabetic rats with suppressed tissue expression of eNOS and enhanced levels of pro-inflammatory reactions. Treatment with intraperitoneal injection of Ex4 (0.5 μg/kg/d) significantly reduced the area of gastric ulcer without changing blood glucose level. Ex-4 restored the expression of pro-angiogenic factors, and attenuated the generation of regional inflammation and superoxide anions. The improvement of ulcer healing was associated with increased expression of MMP-2 and formation of granulation tissue in the peri-ulcer area.

Conclusion

Administration of Ex4 may induce pro-angiogenic, anti-inflammatory and anti-oxidative reactions in the peri-ulcer tissue of diabetic rats that eventually enhances tissue granulation and closure of ulcerative wounds. Our results support the potential clinical application of Glp-1 analogues as supplementary hypoglycemic agents in the antipeptic ulcer medication in diabetes.