Inhibition of proliferation of Pseudomonas aeruginosa by KGF in an experimental burn model using human cultured keratinocytes

Fibroblast growth factor in the treatment of burns: A systematic review

INTRODUCTION

A burn is a trauma that breaks the skin barrier, causing local and systemic responses. Treatment is complex, multiprofessional and expensive. In addition to surgical treatment, topical dressings can be used to keep the wound moist, reduce the risk of infection and stimulate healing. Clinical studies show that topical use of fibroblast growth factors may accelerate healing. An assessment of the quality of the available evidence and its strength of recommendation is necessary.

OBJECTIVE

This study aimed to evaluate the effectiveness and safety of topical use of fibroblast growth factor, compared to other topical treatments or placebo, in the healing of burns, to determine the strength of recommendation.

METHOD

Based on a defined search strategy, randomized and quasi-randomized clinical trials, available in electronic databases, were gathered. These compare the topical use of FGF versus other topical or non-treatment. The primary outcome was healing and as adverse effects: pain, infection and mortality. The systematic review protocol was registered on the PROSPERO platform (CRD42018089556), developed in accordance with the "Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) 2015" and within the "SWiM guideline 2019". GRADEpro was used for the critical analysis of the methodology of the studies.

RESULTS

Four clinical trials were found, in which FGF reduced the healing time and improved the appearance of the scar. Two trials were determined to be of low strength, while two others have a moderate recommendation strength.

CONCLUSION

This review gathered available evidence, between low and moderate recommendation strength for the use of FGF as a topical dressing. Further rigorous trials are needed to improve the strength of recommendation for topical use of FGF for burns.

Keratinocyte growth factor and the expression of wound-healing-related genes in primary human keratinocytes from burn patients

PURPOSE

To evaluate the effect of keratinocyte growth factor (KGF) treatment on the expression of wound-healing-related genes in cultured keratinocytes from burn patients.

METHODS

Keratinocytes were cultured and divided into 4 groups (n=4 in each group): TKB (KGF-treated keratinocytes from burn patients), UKB (untreated keratinocytes from burn patients), TKC (KGF-treated keratinocytes from controls), and UKC (untreated keratinocytes from controls). Gene expression analysis using quantitative polymerase chain reaction (qPCR) array was performed to compare (1) TKC versus UKC, (2) UKB versus UKC, (3) TKB versus UKC, (4) TKB versus UKB, (5) TKB versus TKC, and (6) UKB versus TKC.

RESULTS

Comparison 1 showed one down-regulated and one up-regulated gene; comparisons 2 and 3 resulted in the same five down-regulated genes; comparison 4 had no significant difference in relative gene expression; comparison 5 showed 26 down-regulated and 7 up-regulated genes; and comparison 6 showed 25 down-regulated and 11 up-regulated genes.

CONCLUSION

There was no differential expression of wound-healing-related genes in cultured primary keratinocytes from burn patients treated with keratinocyte growth factor.

Keratinocyte growth factor-2 inhibits bacterial infection with Pseudomonas aeruginosa pneumonia in a mouse model

To determine protective effects of concurrent administration of Keratinocyte growth factor-2 (KGF-2) with Pseudomonas aeruginosa (P. aeruginosa) inoculation on the induced pneumonia. KGF-2 (5 mg/kg) was concurrently administered into the left lobe of 55 mice with P. aeruginosa PAO1 (5 × 10(6) CFU, half-lethal dose); 55 mice in the control group were concurrently administered PBS with the PAO1. We detected and analyzed: body temperature; amount of P. aeruginosa in homogenates; count of total number of nucleated cells and of mononuclear macrophages; protein concentration in bronchoalveolar lavage fluid (BALF); lung wet-to-dry weight ratio; cytokines in BALF and blood; and lung morphology. To study survival rate, concurrent administration of KGF-2 (experimental group) versus PBS (control) with a lethal dose of PAO1 (1 × 10(7) CFU was performed, and survivorship was documented for 7 days post-inoculation. The bacterial CFU in lung homogenates was significantly decreased in the KGF-2 group compared to the control group. There were significantly more mononuclear macrophages in the BALF from the KGF-2 group than from the control group (p < 0.05). KGF-2 increased the surfactant protein and GM-CSF mRNA in lung at 6 h and 72 h after inoculation. Significant reduction of lung injury scores, protein concentrations, lung wet-to-dry weight ratio, and IL-6 and TNF-α levels was noted in the KGF-2 treated rats at 72 h after inoculation (p < 0.05). The 7-day survival rate of the KGF-2 group was significantly higher than that of the control group (p < 0.05). Concurrent administration of KGF-2 facilitates the clearance of P. aeruginosa from the lungs, attenuates P. aeruginosa-induced lung injury, and extends the 7-day survival rate in mice model with P. aeruginosa pneumonia.

Human beta defensin-4 and keratinocyte growth factor gene expression in cultured keratinocyte and fibroblasts of burned patients

PURPOSE

To evaluate KGF and human beta defensin-4 (HBD-4) levels produced by dermic fibroblasts and keratinocytes cultivated from burned patients' skin samples.

METHODS

Keratinocytes and fibroblasts of 10 patients (four major burns, four minor burns and two controls) were primarily cultivated according to standard methods. HBD-4 and KGF genes were analyzed by quantitative PCR.

RESULTS

In fibroblasts, KGF gene expression was 220±80 and 33.33±6.67 (M±SD; N=4), respectively for major and minor burn groups. In keratinocytes, KGF gene expression was 11.2±1.9 and 3.45±0.37 (M±SD; N=4), respectively for major and minor burn groups. In fibroblasts, HBD-4 gene expression was 15.0±4.0 and 11.5±0.5 (M±SD; N=4), respectively for major and minor burn. In keratinocyte, HBD-4 gene expression was 0.0±0.0 and 13.4±4.8 (M±SD; N=4), respectively for major and minor burn.

CONCLUSIONS

KGF expression was increased in burn patient fibroblasts compared to control group. In keratinocytes culture, KGF suppression is inversely proportional to burn extension; it is active and increased in major burn but decreased in minor burn. HBD-4 expression was increased in fibroblasts and decreased in keratinocytes from all burned patients.

Amphotericin B releasing nanoparticle topical treatment of Candida spp. in the setting of a burn wound

Candida spp. infection in the context of burn wounds leads to invasive disease with a 14-70% mortality rate. Unfortunately, current administrations of AmB, an important therapeutic demonstrating minimal resistance, are only available via potentially cytotoxic IV infusions. In order to circumvent these sequelae, we investigated the efficacy of nanoparticle encapsulated AmB (AmB-np) as a topical therapeutic against Candida spp. (drug release equilibrated solubilized AmB [AmB-sol] included as control). Clinical strains demonstrated equal or enhanced killing efficacy with 72.4-91.1% growth reduction by 4 hours. AmB-nps resulted in statistically significant reduction of fungal biofilm metabolic activity ranging from 80% to 95% viability reduction (P<0.001). Using a murine full-thickness burn model, AmB-np exhibited a quicker efficiency in fungal clearance versus AmB-sol by day three, although wound healing rates were similar. These data support the concept that AmB-np can function as a topical antifungal in the setting of a burn wound.

FROM THE CLINICAL EDITOR

The control of fungal infections with Candida species remains a challenge in the context of burn wounds. A nanoencapsulated topical amphotericin-B compound was studied in a murine model of full thickness burn injury, showing remarkable efficacy in controlling Candida infection. This may become a viable alternative to the potentially toxic intravenous formulations.

The role of VIP in cornea

PURPOSE

Exogenous vasoactive intestinal peptide (VIP) down-regulates pro-inflammatory but up-regulates anti-inflammatory cytokines, growth factors (GFs) and Toll-like receptors promoting healing in experimental Pseudomonas aeruginosa (P. aeruginosa) keratitis. Whether VIP is required for GF or GF receptor (R) expression in normal and infected corneas is unknown and is the purpose of this study.

METHODS

VIP knockout ((-/-)) and wild-type (WT) C57BL/6 (B6) mice were infected and tested using PCR array, real-time RT-PCR, ELISA, and immunostaining. VIP antagonist treatment studies also were done using B6 and BALB/c mice.

RESULTS

Infected corneas of VIP(-/-) versus WT B6 mice perforated earlier (2 vs. 5 days postinfection [p.i.]), and array data showed that GFs were differentially changed between groups. RT-PCR revealed that the infected cornea of VIP(-/-) versus WT mice expressed higher mRNA levels of epidermal growth factor (EGF) and hepatocyte growth factor (HGF), reduced FGF, EGFR, and HGFR, with no difference in FGFR; differences between groups were not seen in normal cornea. Immunostaining for GF and GFR in the normal cornea of VIP(-/-) versus WT mice was similar. However, at 1 day p.i., VIP(-/-) versus WT mice had more intense EGF and HGF, similar FGFR, and reduced FGF, EGFR, and HGFR staining. VIP antagonist treatment decreased protein levels for GFR at 5 days p.i. in both B6 and BALB/c mice, with no significant changes in normal cornea.

CONCLUSIONS

The data showed that endogenous VIP is not requisite for GF or GFR expression in the normal cornea but, after infection, its absence or reduction is critical for their regulation.

An optimized animal model for partial and total skin thickness burns studies

PURPOSE

Development of an improved animal model for studying skin burns in rats.

METHODS

Twenty-four male Wistar rats were randomly assigned to four groups (n=6): G1-Control, G2- T100°C, G3-T150°C and G4-T200°C. Two 10 x 10 mm squares were outlined with a sterile surgical marker on each side and along the vertebral column using a prepared template positioned between the anterior and posterior limbs. G2-G4 rats were subjected to 100°C, 150°C and 200ºC thermal burns, respectively. G1 rats served as controls. Burns were inflicted by applying a copper plate connected to an electronic temperature controlling device to the dorsal skin of anesthetized rats. Four burns were produced on each animal (total area: 4 cm²/animal) leaving about 1 cm of undamaged skin between burn areas. Analgesia was administered during 24 h after burn injury by adding 30 mg codeine phosphate hemihydrate to 500 ml tap water.

RESULTS

The application of 100°C and 150ºC resulted in partial thickness skin burns with central reepithelialization of the burned area only at 100°C. In G4 group the whole thickness of the skin was injured without central reepithelialization. However, there was marginal reepithelialization in all groups.

CONCLUSION

The model studied is inexpensive and easily reproducible, enabling the achievement of controlled burns with partial or total impairment of the skin in experimental animals.

Control of the skin scarring response

There comes a time when the understanding of the cutaneous healing process becomes essential due to the need for a precocious tissue repair to reduce the physical, social, and psychological morbidity. Advances in the knowledge on the control of interaction among cells, matrix and growth factors will provide more information on the Regenerative Medicine, an emerging area of research in medical bioengineering. However, considering the dynamism and complexity of the cutaneous healing response, it is fundamental to understand the control mechanism exerted by the interaction and synergism of both systems, cutaneous nervous and central nervous, via hypothalamus hypophysis-adrenal axis, a relevant subject, but hardly ever explored. The present study reviews the neuro-immune-endocrine physiology of the skin responsible for its multiple functions and the extreme disturbances of the healing process, like the excess and deficiency of the extracellular matrix deposition.

Proliferation of fibroblasts cultured on a hemi-cellulose dressing

In recent times, hemi-cellulose dressing (HD) has been used clinically with satisfactory rates of success [Melandri D, De Angelis A, Orioli R, et-al. Use of a new hemicellulose dressing (Veloderm) for the treatment of split-thickness skin graft donor sites A within-patient controlled study. Burns 2006 Dec;32:964-72.]; however, the effect of cellulose dressings on the wound-healing process is unclear due to paucity of experimental data. This study aimed to determine the adhesion and proliferation of human skin fibroblasts, which were cultured in vitro using the explant technique, on HD. Cells were seeded onto HD discs and evaluated for cell adhesion and cell proliferation after 7, 14 and 21 days. Fibroblasts displayed 70% adhesion to HD after 24h. The HD discs seeded with a density of 5x10(4) cells per well showed a proliferation rate of 12% on day 7, 30% on day 14 and 75% on day 21. The results demonstrated that HD can sustain fibroblast proliferation--a highly desirable characteristic for an ideal skin substitute.