Lactobacillus Plantarum Promotes Wound Healing by Inhibiting the NLRP3 Inflammasome and Pyroptosis Activation in Diabetic Foot Wounds

Objective

Diabetic foot ulcer (DFU) impairs the quality of life of diabetic patients and overburdens healthcare systems and society. It is crucial to comprehend the pathophysiology of DFU and develop effective treatment strategies. The aim of this study was to to evaluate the therapeutic potential of Lactobacillus Plantarum (LP) on wound healing in DFU and to explore the underlying mechanisms.

Methods

To investigate the effects of LP on wound healing, human umbilical vein endothelial cells (HUVECs) were treated with advanced glycation end products (AGEs) and used to assess cell viability, migration, and pyroptosis using CCK-8, cell scratch, and flow cytometry. The levels of IL-1β and IL-18 were measured by ELISA. The expression of NLRP3, caspase-1 p20, and GSDMD-N was detected by Western blot. Additionally, NLRP3 inhibitor MCC950 was used to treat a diabetic rat model established by streptozotocin (STZ). Pearson correlation analysis was performed to analyze the relationship between LP and NLRP3, IL-1β, IL-18 in ulcer tissue.

Results

Our data mechanistically demonstrate that AGEs activate the NLRP3/Caspase-1/GSDMD pathway, leading to an increase in the levels of IL-1β and IL-18 and ultimately promoting cell pyroptosis. Furthermore, we identified that LP inhibits the effects of AGEs by downregulating NLRP3 inflammasome activity. LP facilitated wound healing in diabetic rats and resulted in decreased protein levels of NLRP3 and its downstream target caspase-1 p20. Finally, we observed a negative correlation between LP and NLRP3, IL-1β, IL-18 in diabetic foot skin tissue.

Conclusion

Our findings uncovered a novel role of LP in diabetic foot wound healing via regulation of the NLRP3 inflammasome, suggesting this link as a therapeutic target. In future research, it would be valuable to explore the signaling cascades involved in LP-mediated inhibition of NLRP3 inflammasome activation.

P. aeruginosa interactions with other microbes in biofilms during co-infection

This review addresses the topic of biofilms, including their development and the interaction between different counterparts. There is evidence that various diseases, such as cystic fibrosis, otitis media, diabetic foot wound infections, and certain cancers, are promoted and aggravated by the presence of polymicrobial biofilms. Biofilms are composed by heterogeneous communities of microorganisms protected by a matrix of polysaccharides. The different types of interactions between microorganisms gives rise to an increased resistance to antimicrobials and to the host's defense mechanisms, with the consequent worsening of disease symptoms. Therefore, infections caused by polymicrobial biofilms affecting different human organs and systems will be discussed, as well as the role of the interactions between the gram-negative bacteria Pseudomonas aeruginosa, which is at the base of major polymicrobial infections, and other bacteria, fungi, and viruses in the establishment of human infections and diseases. Considering that polymicrobial biofilms are key to bacterial pathogenicity, it is fundamental to evaluate which microbes are involved in a certain disease to convey an appropriate and efficacious antimicrobial therapy.

Novel home use of mechanical negative pressure wound therapy in diabetic foot ulcers

OBJECTIVE

Mechanical negative pressure wound therapy is an ultraportable, light weight and disposable single-use device that has been shown to promote wound healing. This study evaluated home use of a mechanically powered negative pressure wound therapy (NPWT) in diabetic foot wounds.

METHODS

Patients underwent revascularisation and/or debridement or amputation before starting mechanical NPWT. Wound outcomes and images of the wounds were recorded at each follow-up visit by the wound nurse. Patients were followed up until wound closure or end of therapy.

RESULTS

A total of 12 patients (each with one wound) were included in the study. Of the 12 wounds, 33.3% (n=4) of wounds achieved primary wound closure while the remaining 66.6% (n=8) of wounds demonstrated a mean wound size reduction of 37.5±0.13%. Of the closed wounds, mean time to healing was 4.75±2.50 weeks. There was 100% limb salvage with no further debridement or amputations, and no 30-day unplanned readmissions. Mean length of hospital stay before starting home NPWT was 9.75±6.31 days. Mean number of NPWT changes was 8.33±2.67 sessions, while mean duration of therapy was 4.0±1.54 weeks. Mean cost of home NWPT therapy was US$1904±731 per patient.

CONCLUSION

The home use of mechanically powered NPWT in diabetic foot wounds demonstrated excellent wound healing rates and 100% limb salvage, with no complications.

Effect of Negative Pressure Wound Therapy on Cellular Fibronectin and Transforming Growth Factor-β1 Expression in Diabetic Foot Wounds

BACKGROUND

Chronic diabetic foot wounds are a leading cause of amputation, morbidity, and hospitalization for patients with diabetes. Negative-pressure wound therapy (NPWT) can putatively facilitate wound healing, but the underlying mechanisms remain unclear. Cellular fibronectin (cFN) and transforming growth factor-β1 (TGF-β1) play an important role in wound healing. This prospective randomized controlled trial evaluated the effects of NPWT on the production of cFN and the expression of TGF-β1 in diabetic foot wounds of patients.

METHODS

From January 2012 to January 2015, 40 patients with diabetic foot wounds were randomly and equally apportioned to receive either NPWT or advanced moist wound therapy (control) for 7 days. Granulation tissue was harvested before and after treatment. Immunohistochemistry and Western blot were performed to evaluate protein levels of cFN and TGF-β1, and real-time polymerase chain reaction (PCR) to measure corresponding mRNA expressions.

RESULTS

NPWT facilitated the expression of cFN and TGF-β1 in diabetic foot wounds. Immunohistochemical analysis revealed higher levels of cFN and TGF-β1 in the NPWT group than in the control group. Western blot and real-time PCR analysis further showed that protein and mRNA levels of cFN or TGF-β1 were higher in the NPWT group than that in the control group ( P < .01, both).

CONCLUSION

Our results showed that NPWT facilitated the production of cFN and the expression of TGF-β1 in granulation tissue in diabetic foot ulcers.

LEVEL OF EVIDENCE

Level I, randomized controlled study.

Flexor Tenotomy Improves Healing and Prevention of Diabetes-Related Toe Ulcers: A Systematic Review

Toe deformities are common in people with diabetes and are often associated with toe ulcers. Operative procedures have been used to reduce toe deformities, because these were proposed to be beneficial in the management of toe ulcers. The present systematic review investigated the effect of flexor tenotomy to address toe deformity for healing and preventing diabetes-related toe ulcers. Four electronic databases were searched in January 2016. Studies were included if they had reported the effects of flexor tenotomy for healing and/or preventing diabetes-related toe ulcers. Six studies with a total of 264 flexor tenotomies performed on toes with ulcers and 57 performed as a prophylactic procedure were included. The mean duration of preoperative ulceration was 207.9 (range 7 to 1825) days. The mean duration to postoperative ulcer healing was 29.5 days, with an overall healing rate of 97%. The rate of ulcer recurrence was 6%. All the toes that had undergone prophylactic flexor tenotomy remained free of ulceration. Overall, the rate of complications was low. Flexor tenotomy to address toe deformity is relatively safe and effective in healing and preventing diabetes-related toe ulcers. Flexor tenotomy should be considered in the management of diabetes-related toe ulcers in the presence of toe deformities.