Green Antimicrobials as Therapeutic Agents for Diabetic Foot Ulcers

Enhancement of wound healing in diabetic mice by topical use of a peptide-ionic liquid conjugate

Diabetic foot ulcers (DFU) are one of the most devastating complications of diabetes, with high impact on patient's quality of life. In worst scenarios, DFU can lead to severe amputation or even death. DFUs are an easy target for microbial pathogens and their effective healing is hampered by the galloping increase of microbial resistance to antibiotics, including from the most prevalent pathogens in DFU, e.g. Staphylococcus aureus. As such, available antibiotics show poor efficacy in the treatment of DFU, leading to a chronic condition that is exacerbated by poor healing rates due to the persistent inflammation, poor oxygenation and low angiogenesis, leading to high risk of ischemia, among other conditions that typically affect patients with diabetes. Our group has recently designed new peptide-based strategies towards the topical treatment of DFU, whereby peptide-ionic liquid conjugates emerged as highly promising agents. One of the best such conjugates, C16-Im-PP4, results from coupling an imidazolium-based ionic liquid with intrinsic antimicrobial activity to the N-terminus of a collagen boosting peptide used in cosmetics, the pentapeptide-4. C16-Im-PP4 showed excellent in vitro properties, namely, wide-spectrum antimicrobial action and collagen-boosting effect on human dermal fibroblasts, prompting the in vivo study here reported. The peptide-ionic liquid conjugate was applied topically on wounds of mice with diabetes. The results show multitargeted actions, at a dose of 1 µg/wound including: i) anti-inflammatory; ii) antioxidant; iii) pro-collagenic; vi) pro-angiogenic; v) antimicrobial; and vi) improved wound maturation effects. Altogether, these results identify this technology as a novel topical treatment for DFU.

Clinical Effects of Thread-Dragging Therapy on Gangrene of Non-ischemic Diabetic Foot Ulcers

OBJECTIVE

To investigate the clinical effects of thread-dragging therapy on gangrene of non-ischemic diabetic foot ulcers (NIDFU).

METHODS

A total of 136 patients with NIDFU were recruited from the Department of Peripheral Vascular Surgery, Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine between June 21, 2021 and February 1, 2023, and randomized into an intervention group and a control group, with 68 cases in each group. Both groups received basic treatment. The intervention group was treated with thread-dragging therapy, while the control group was treated with debridement combined with routine dressing changes after surgery. Both groups were treated continuously for 2 months. The amputation rates and changes in the ulcer area were compared between the groups. The inflammatory response index including peripheral white blood cells (WBCs), neutrophil percentage (NEUT%), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), procalcitonin (PCT), and interleukin 6 (IL-6) were compared between the two groups.

RESULTS

After treatment, the ulcer areas in the intervention group were significantly smaller than that of the control group (8.50±3.88 cm2 vs. 10.11±4.61 cm2, P<0.05). The amputation rates of the two groups were not statistically significant (4.4% vs. 5.9%, P>0.05). Differences of WBCs count, CRP, and ESR before and after therapy in the intervention group were better than the control group (P<0.05). However, there were no significant differences in changes of NEUT%, PCT, and IL-6 between the two groups (P>0.05).

CONCLUSION

Thread-dragging therapy may be effective in the treatment of NIDFU, with the additional advantages of less tissue damage after healing. (Registration No. ChiCTR2100047496).

Zinc-based Polyoxometalate Nanozyme Functionalized Hydrogels for optimizing the Hyperglycemic-Immune Microenvironment to Promote Diabetic Wound Regeneration

BACKGROUND

In diabetic wounds, hyperglycemia-induced cytotoxicity and impaired immune microenvironment plasticity directly hinder the wound healing process. Regulation of the hyperglycemic microenvironment and remodeling of the immune microenvironment are crucial.

RESULTS

Here, we developed a nanozymatic functionalized regenerative microenvironmental regulator (AHAMA/CS-GOx@Zn-POM) for the effective repair of diabetic wounds. This novel construct integrated an aldehyde and methacrylic anhydride-modified hyaluronic acid hydrogel (AHAMA) and chitosan nanoparticles (CS NPs) encapsulating zinc-based polymetallic oxonate nanozyme (Zn-POM) and glucose oxidase (GOx), facilitating a sustained release of release of both enzymes. The GOx catalyzed glucose to gluconic acid and (H₂O₂), thereby alleviating the effects of the hyperglycemic microenvironment on wound healing. Zn-POM exhibited catalase and superoxide dismutase activities to scavenge reactive oxygen species and H₂O₂, a by-product of glucose degradation. Additionally, Zn-POM induced M1 macrophage reprogramming to the M2 phenotype by inhibiting the MAPK/IL-17 signaling diminishing pro-inflammatory cytokines, and upregulating the expression of anti-inflammatory mediators, thus remodeling the immune microenvironment and enhancing angiogenesis and collagen regeneration within wounds. In a rat diabetic wound model, the application of AHAMA/CS-GOx@Zn-POM enhanced neovascularization and collagen deposition, accelerating the wound healing process.

CONCLUSIONS

Therefore, the regenerative microenvironment regulator AHAMA/CS-GOx@Zn-POM can achieve the effective conversion of a pathological microenvironment to regenerative microenvironment through integrated control of the hyperglycemic-immune microenvironment, offering a novel strategy for the treatment of diabetic wounds.

Multifunctional nanocomposites mediated novel hydrogel for diabetic wound repair

The regeneration and repair of diabetic wounds, especially those including bacterial infection, have always been difficult and challenging using current treatment. Herein, an effective strategy is reported for constructing glucose-responsive functional hydrogels using nanocomposites as nodes. In fact, tannic acid (TA)-modified ceria nanocomposites (CNPs) and a zinc metal-organic framework (ZIF-8) were employed as nodes. Subsequent crosslinking with 3-acrylamidophenylboronic acid achieved functional nanocomposite-hydrogels (TA@CN gel, TA@ZMG gel) by radical-mediated polymerization. Compared with a simple physically mixed hydrogel system, the mechanical properties of TA@CN gel and TA@ZMG gel are significantly enhanced due to the intervention of the nanocomposite nodes. In addition, this kind of nanocomposite hydrogel can realize the programmed loading of drugs and release of drugs in response to glucose/PH, to coordinate and promote its application in the regeneration and repair of diabetic wounds and infected diabetic wounds. Specifically, TA@CN gel can remove reactive oxygen species and generate oxygen through its various enzymatic activities. At the same time, it can effectively promote neovascularization, thus promoting the regeneration and repair of diabetic wounds. Furthermore, glucose oxidase-loaded TA@ZMG gel exhibits glucose response and pH-regulating functions, triggering programmed metformin (Met) release by degrading the metal-organic framework (MOF) backbone. It also exhibited additional synergistic effects of antibacterial activity, hair regeneration and systemic blood glucose regulation, which make it suitable for the repair of more complex infected diabetic wounds. Overall, this novel nanocomposite-mediated hydrogel holds great potential as a biomaterial for the healing of chronic diabetic wounds, opening up new avenues for further biomedical applications.

In Vitro Effect of Eucalyptus Essential Oils and Antiseptics (Chlorhexidine Gluconate and Povidone-Iodine) against Bacterial Isolates from Equine Wounds

Considering the increasing antibiotics resistance, there has been a propensity to replace them with antiseptics when it comes to wound management and treatment. Nevertheless, in recent years, there have been reports regarding resistance to antiseptics by some bacterial strains. There is also concern about the environmental impact of these substances. The aim of this study was to compare the antimicrobial efficacy of antiseptics and eucalyptus essential oils on bacterial strains from horse's wounds. We used twelve Escherichia coli, eight Staphylococcus aureus, two Staphylococcus pseudintermedius, one Staphylococcus vitulinus and one Staphylococcus saprophyticus strains from equine wounds. The effect of Eucalyptus radiata essential oil, Eucalyptus globulus essential oil, povidone-iodine and chlorhexidine gluconate against the isolated strains was evaluated applying the Kirby-Baüer method. Regarding the Escherichia coli strains, E. radiata and the mixture of E. radiata and E. globulus had a better inhibitory effect than antiseptics. E. globulus had a better effect against most Staphylococcus spp. compared to E. radiata. For both Gram-negative and Gram-positive strains tested, chlorhexidine gluconate had a better inhibitory effect than povidone-iodine. The antibacterial efficacy of essential oils highlights their potential to substitute or complement the use of antiseptics and so reduce resistance to antiseptics.

Green Antimicrobials

In the last couple of years, the awareness of climate change and high pollution levels have raised our sense of ecological responsibility [...].