Maggot treatment promotes healing of diabetic foot ulcer wounds possibly by upregulating Treg levels

PURPOSE

Through the study of regulatory T cells (Tregs), we found a possible way to promote the healing of diabetic foot ulcers (DFUs) with maggot treatment and investigated the associated mechanism.

METHODS

Immunohistochemistry was used to examinetissues from DFU patients treated with or without maggot debridement therapy (MDT). The expression of the signature Treg molecule Foxp3, interleukin-10 (IL-10), transforming growth factor-beta (TGF-β), and interferon regulatory factor 4 (IRF-4) in patients with DFU treated with or without MDT was tested by real-time PCR (RT-PCR). CD4⁺ T cells from mouse spleen cells were cocultured in vitro with maggot excretions/secretions (ES), and Foxp3, IL-10, TGF-β, and IRF-4 levels were measured by RT-PCR.

RESULTS

Foxp3 expression was obviously increased in DFU patients treated using MDT but less pronounced in those treated without MDT (P < 0.05). Foxp3, IL-10, TGF-β, and IRF-4 gene expression levels were higher in DFU patients treated with MDT than in those treated without MDT. Moreover, in vitro coculture of mouse spleen cells with ESs produced results consistent with the in vivo results (P < 0.001).

CONCLUSION

MDT/ESs can obviously upregulate the Treg level and may affect DFU healing in different ways, suggesting a new direction for the future treatment of DFU.

Genome and transcriptome sequencing of the green bottle fly, Lucilia sericata, reveals underlying factors of sheep flystrike and maggot debridement therapy

The common green bottle blow fly Lucilia sericata (family, Calliphoridae) is widely used for maggot debridement therapy, which involves the application of sterile maggots to wounds. The larval excretions and secretions are important for consuming necrotic tissue and inhibiting bacterial growth in wounds of patients. Lucilia sericata is also of importance as a pest of sheep and in forensic studies to estimate a postmortem interval. Here we report the assembly of a 565.3 Mb genome from long read PacBio DNA sequencing of genomic DNA. The genome contains 14,704 predicted protein coding genes and 1709 non-coding genes. Targeted annotation and transcriptional analyses identified genes that are highly expressed in the larval salivary glands (secretions) and Malpighian tubules (excretions) under normal growth conditions and following heat stress. The genomic resources will underpin future genetic studies and in development of engineered strains for genetic control of L. sericata and for biotechnology-enhanced maggot therapy.

Bacterial association observations in Lucilia sericata and Lucilia cuprina organs through 16S rRNA gene sequencing

Blowfly (Diptera: Calliphoridae) species Lucilia sericata (Meigen) and related species Lucilia cuprina (Wiedmann) are important agricultural pests, assist in forensic fields and also have a therapeutic role in medicine. Both species (though predominantly L. sericata) are utilised in a clinical setting for maggot debridement therapy (MDT) where the larvae ingest necrotic tissue and bacteria from non-healing wounds. Conversely, larvae of L. cuprina feed invasively, as major initiators of sheep myiasis in Australia, New Zealand, and the UK, among other regions. Both species exhibit larval and adult interactions with bacterially rich environments, but the significance of this in the composition of their microbiome has yet to be considered. This study utilised dissected samples of digestive and reproductive organs from both disinfected and non-disinfected adults and larvae of both species for bacterial DNA extraction, followed by 16S rRNA gene sequencing. Sequencing data indicated unsurprisingly that digestive tracts of both genders and female salivary glands from all non-disinfected samples carry the most concentrated amounts of bacteria. Genera Pseudomonas and Corynebacterium were also highly represented within all organs and species analysed. Comparison of bait lures to sample sequence read output of insect specimens showed no correlation with genera such as Pseudomonas present in insects, while absent from wild bait, and in reduced amounts from fleece bait profiles. With this information, future work can focus on key organs such as the spermathecae and salivary glands, while also providing the potential to identify the role these bacteria may play in the blowfly life cycle. KEY POINTS: Genera Pseudomonas appears consistently in the microbiome of Lucilia species. Female spermathecae and salivary glands show the highest microbial diversity. Bacterial profiles of L. sericata and L. cuprina have similar composition.

Using a combination therapy to combat scalp necrosis: a case report

BACKGROUND

Chronic nonhealing wounds are very expensive to treat and debilitating, and they reduce health-related quality of life. Scalp necrosis is very rare due to its rich vascularity. However, any post-traumatic wounds with secondary infection can lead to scalp necrosis.

CASE PRESENTATION

We report a case of a 77-year-old Azerbaijani man with a history of diabetes who had a car accident and sustained a scalp wound. He underwent reconstructive surgery for the scalp wound. The wound became infected, and scalp necrosis developed following the surgery. There was no progress in wound healing in spite of conventional wound therapy. We combined maggot debridement therapy with negative-pressure wound therapy and amniotic membrane grafting for 7 months. Necrotic tissues began to be eliminated after the second use of larva therapy, and the wound became free of necrotic tissues with clear increase of granulated tissues after four treatments with maggot debridement therapy. Then, we applied negative-pressure wound therapy and amniotic membrane grafting to accelerate wound healing and improve wound closure. The patient's scalp wound recovered well, and he was discharged to home in good condition.

CONCLUSIONS

Medical and wound care teams can benefit from this combination therapy when dealing with nonhealing necrotic wounds.

In vitro evaluation of the association of medicinal larvae (Insecta, Diptera, Calliphoridae) and topical agents conventionally used for the treatment of wounds

Wound healing is a complex process involving multiple biochemical and cellular events and represents a neglected public health issue. As a consequence, millions of people worldwide suffer from chronic wounds. The search for new treatment alternatives is therefore an important issue. In the context of wound healing, Maggot Debridement Therapy (MDT) is an inexpensive treatment with few contraindications and very promising results. This study aimed to evaluate the in vitro feasibility and implications of larvae (= MDT) use when combined with topical agents as a strategy to identify additive or synergistic combinations. The weight and survival rate of Cochliomyia macellaria (Fabricius) (Insecta, Diptera, Calliphoridae) larvae reared in an in vitro wound with either honey, hydrogel, 10% papain gel, essential fatty acids (EFA), collagenase, or silver sulfadiazine were evaluated after 24, 48 and 72 h. Hydrogel (for weight: 24 and 72 h; for survival: 24 h) and 10% papain gel (for weight: 48 h; for survival: 48 and 72 h) demonstrated the least interference in larval weight gain and survival rate, when compared to the control group. The results obtained in this study showed that the combined use of larvae and hydrogel or 10% papain gel may be promising to maximize the tissue repair. Honey, EFA and collagenase could be used to prepare the bed of the dry wounds to receive the MDT.

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.

Treatment of pressure ulcers with larvae of Lucilia sericata

Objectives

This study aims to investigate the use of the Lucilia sericata larvae in patients with decubitus ulcers resistant to hyperbaric oxygen treatment, vacuum-assisted closure, surgical debridement, and other conventional therapies.

Patients and methods

A total of 36 patients (21 females, 15 males; mean age 63.7 years; range 16 to 90 years) who were admitted to our hospital for decubitus ulcers between February 2011 and July 2016 were included in our study. All patients had one or more lesions in the sacral region, trochanteric area, dorsal region, or on the heel of the foot. Nine patients had spinal cord injuries, six of them were injured during a car accident, and three of them had spinal cord injuries due to gunshot. One patient had concomitant lung cancer, one had heart failure, and two patients had a diagnosis of multiple sclerosis. Thirty three of 36 patients were admitted to the wound therapy unit within the department of emergency medicine, and three were admitted to the physical therapy and rehabilitation clinic. For each patient, Lucilia sericata maggots were applied on the lesions for 72 hours and, then, washed away. This procedure was repeated two times a week. Twenty nine patients (78.9%) had four to six sessions and seven patients (21.1%) had eight to 12 sessions.

Results

Twenty nine lesions (78.9%) were Grade 2 and 3 and were completely healed after four to eight treatment sessions, while seven lesions (21.1%) were completely cured at the end of 10 to 14 sessions. There was complete clearance of necrotic debris at the end of two sessions within the first week for 15 lesions, whereas 10 lesions (27.8%) were cured after four sessions within two weeks, seven lesions (19.4%) within five sessions after three weeks, and four lesions (11.1%) were treated at the end of seven sessions for four weeks. All the necrotic crusts over the surface of the ulcers were cleaned and bad odor of the lesions disappeared.

Conclusion

Lucilia sericata larvae debridement is a rapid and effective treatment option for the management of chronic decubitus ulcers which are resistant to conventional therapies and other treatment modalities such as hyperbaric oxygen, vacuum-assisted closure, and surgical debridement.

Maggot debridement therapy with a direct dressing can cause compression injuries in patients with chronic limb ischemia

While there are no reports regarding dressing-associated iatrogenic skin ulcer as an adverse event of maggot debridement therapy (MDT), MDT is clinically used on patients with critical limb ischaemia with dermal fragility. Herein we report causes and counter measures for a case of iatrogenic skin ulcer induced by MDT dressing.

Urate Oxidase produced by Lucilia sericata medical maggots is localized in Malpighian tubes and facilitates allantoin production

Lucilia sericata maggots are the only species currently approved for maggot debridement therapy (MDT), an alternative treatment for chronic and recalcitrant wounds. Maggots promote wound debridement, disinfection and healing by producing a complex mixture of proteins, peptides and low-molecular-weight compounds in their secretions and excretions, but the individual components are not well characterized at the molecular level. Here we investigated the purine catabolism pathway in L. sericata, focusing on the production of allantoin by Urate Oxidase (UO), which is thought to promote wound healing. We produced recombinant L. sericata UO in Escherichia coli, and characterized the properties of the pure enzyme in terms of the optimum pH (7-10) and temperature (20-25 °C), its stability, sensitivity to inhibition and ion dependency. We used quantitative RT-PCR and RNA in situ hybridization to monitor the expression of the UO gene, and we used a guinea pig anti-UO antibody to detect the native enzyme by western blot and by florescence immunohistochemistry in larval tissues. We found that L. sericata UO is exclusively present in the larval excretion organ (the Malpighian tubes) and is freely available in the cytoplasm rather than restricted to a specific subcellular compartment. Allantoin is a final product of L. sericata purine catabolism. It is produced by UO in the Malpighian tubes to remove uric acid from the hemolymph and is consequently excreted via the hindgut. Our findings confirm the hypothesis that both actively secreted molecules and excretion products contribute to the beneficial effects of MDT.

Increasing the miR-126 expression in the peripheral blood of patients with diabetic foot ulcers treated with maggot debridement therapy

BACKGROUND

miR-126 may increase angiogenesis in patients with diabetic foot ulcers (DFUs) treated with maggot debridement therapy (MDT).

METHODS

Real-time quantitative PCR was used to detect expression of miR-126 mRNA in the peripheral blood among the non-diabetic population, type 2 diabetes mellitus patients without DFU, and patients with DFUs of type 2 diabetes mellitus. The expression of miR-126 mRNA in the peripheral blood of patients with DFUs was observed before and after MDT. Finally, human umbilical vein endothelial cells (HUVEC) were utilized to explore miR-126 mRNA expression with maggot excretions/secretions (ES).

RESULTS

In the patients with DFUs, the miR-126 mRNA expression level in the peripheral blood was less than that type 2 diabetes mellitus patients without DFU, and much lower than that in the non-diabetic population (P<0.001). The miR-126 expression level was significantly increased in those DFU patients treated with MDT (P<0.05). Finally, using HUVEC co-cultured with ES, we showed the ES increased miR-126 expression in vitro (P<0.001).

CONCLUSION

MDT upregulates the miR-126 expression in the peripheral blood of patients with DFUs.

Maggot debridement therapy promotes diabetic foot wound healing by up-regulating endothelial cell activity

To determine the role of maggot debridement therapy (MDT) on diabetic foot wound healing, we compared growth related factors in wounds before and after treatment. Furthermore, we utilized human umbilical vein endothelial cells (HUVECs) to explore responses to maggot excretions/secretions on markers of angiogenesis and proliferation. The results showed that there was neo-granulation and angiogenesis in diabetic foot wounds after MDT. Moreover, significant elevation in CD34 and CD68 levels was also observed in treated wounds. In vitro, ES increased HUVEC proliferation, improved tube formation, and increased expression of vascular endothelial growth factor receptor 2 in a dose dependent manner. These results demonstrate that MDT and maggot ES can promote diabetic foot wound healing by up-regulating endothelial cell activity.