Noninjured Skin Research Articles

Skin Microbial Community Associated to Strawberry Disease in Farmed Rainbow Trout (Oncorhynchus mykiss Walbaum, 1792).

Aquaculture plays a crucial role in addressing the growing global demand for food. However, diseases associated with intensive aquaculture practices, especially those affecting the skin, can present significant challenges to both fish health and the industry as a whole. Strawberry disease (SD), also known as red-mark syndrome, is a persistent and non-lethal skin condition observed in Rainbow Trout (Oncorhynchus mykiss) in the United States and various European countries. SD is a nonlethal skin condition of an unclear etiology that affects rainbow trout reared in freshwater close to the harvest period. We used a RNA-based approach to examine active microbiota in the SD skin lesions and compared to non-injured skin. Our results, based on using 16S rRNA gene next-generation sequencing, showed that the skin microbiota was dominated by the phyla Firmicutes, Proteobacteria, and Actinobacteria. The comparisons of the skin microbiota between injured and non-injured samples showed differences in the alpha diversity (Fisher index) and beta diversity metrics (ANOSIM). At the genus level, both Pseudomonas and Candidatus Midichloria were highlighted as the most abundant taxa detected in samples obtained from fish affected with strawberry diseases. In contrast, the most abundant taxa in non-injured skin were Escherichia-Shigella, Streptococcus, and Pseudoalteromonas. In conclusion, our study on SD revealed distinct differences in the microbiota composition between skin lesions and non-injured skin. This is the first description of microbiota associated with SD-injured skin samples using an RNA approach.

Maintenance of chronicity signatures in fibroblasts isolated from recessive dystrophic epidermolysis bullosa chronic wound dressings under culture conditions

BackgroundRecessive Dystrophic Epidermolysis Bullosa (RDEB) is a rare inherited skin disease caused by variants in the COL7A1 gene, coding for type VII collagen (C7), an important component of anchoring fibrils in the basement membrane of the epidermis. RDEB patients suffer from skin fragility starting with blister formation and evolving into chronic wounds, inflammation and skin fibrosis, with a high risk of developing aggressive skin carcinomas. Restricted therapeutic options are limited by the lack of in vitro models of defective wound healing in RDEB patients.ResultsIn order to explore a more efficient, non-invasive in vitro model for RDEB studies, we obtained patient fibroblasts derived from discarded dressings) and examined their phenotypic features compared with fibroblasts derived from non-injured skin of RDEB and healthy-donor skin biopsies. Our results demonstrate that fibroblasts derived from RDEB chronic wounds (RDEB-CW) displayed characteristics of senescent cells, increased myofibroblast differentiation, and augmented levels of TGF-β1 signaling components compared to fibroblasts derived from RDEB acute wounds and unaffected RDEB skin as well as skin from healthy-donors. Furthermore, RDEB-CW fibroblasts exhibited an increased pattern of inflammatory cytokine secretion (IL-1β and IL-6) when compared with RDEB and control fibroblasts. Interestingly, these aberrant patterns were found specifically in RDEB-CW fibroblasts independent of the culturing method, since fibroblasts obtained from dressing of acute wounds displayed a phenotype more similar to fibroblasts obtained from RDEB normal skin biopsies.ConclusionsOur results show that in vitro cultured RDEB-CW fibroblasts maintain distinctive cellular and molecular characteristics resembling the inflammatory and fibrotic microenvironment observed in RDEB patients’ chronic wounds. This work describes a novel, non-invasive and painless strategy to obtain human fibroblasts chronically subjected to an inflammatory and fibrotic environment, supporting their use as an accessible model for in vitro studies of RDEB wound healing pathogenesis. As such, this approach is well suited to testing new therapeutic strategies under controlled laboratory conditions.

Evaluation of Scar Quality after Treatment of Superficial Burns with Dressilk® and Suprathel®-In an Intraindividual Clinical Setting.

Background: Various synthetic and biological wound dressings are available for the treatment of superficial burns, and standard care differs among hospitals. Nevertheless, the search for an ideal wound dressing offering a safe healing environment as well as optimal scar quality while being economically attractive is a continuing process. In recent years, Dressilk®, which consists of pure silk, has become the standard of care for the treatment of superficial burns in our hospital. However, no long-term scar-evaluation studies have been performed to compare Dressilk® with the often-used and more expensive Suprathel® in the treatment of superficial burns. Methods: Subjective and objective scar evaluations were performed three, six, and twelve months after treatment in patients who received simultaneous treatment of 20 superficial burn wounds with both Suprathel® and Dressilk®. The evaluations were performed using the Vancouver Scar Scale, the Cutometer®, Mexameter®, Tewameter®, and the O2C®. Results: Both dressings showed mostly equivalent results in subjective scar evaluations. In the objective scar evaluations, the wounds treated with Dressilk® showed a faster return to the qualities of non-injured skin. Wound areas treated with the two dressings showed no significant differences in elasticity and transepidermal water loss after 12 months. Only oxygen saturation was significantly lower in wound areas treated with Suprathel® (p = 0.008). Subjectively, wound areas treated with Dressilk® showed significantly higher pigmentation after six months, which was not apparent after 12 months. Conclusion: Both wound dressings led to esthetically satisfying scar recovery without significant differences from normal uninjured skin after 12 months. Therefore, Dressilk® remains an economically and clinically interesting alternative to Suprathel® for the treatment of superficial burns.

No indications for altered EEG oscillatory activity in patients with chronic post-burn itch compared to healthy controls

A large proportion of patients with burn injuries develop chronic itch, which impacts quality of life. The underlying pathophysiological mechanisms are poorly understood. This cross-sectional pilot study investigates whether altered cortical oscillatory processes are involved in chronic post-burn itch. Continuous electroencephalography (EEG) data were recorded during rest and stimulation of non-injured skin, inducing itch (histamine and electrical) and cold-pressor task pain for 15 adults with chronic post-burn itch and 15 matched healthy controls. Quantitative metrics comprised oscillatory power and peak frequencies in theta, alpha, and beta bands. No statistical differences between patients and healthy controls were found in oscillatory activity during rest or stimulation, with Bayesian analysis suggesting equivocal evidence. However, post-traumatic stress symptoms and duration of chronic itch may be associated with changes in oscillatory activity. A lack of differences in cortical oscillatory processing and itch levels at non-injured sites, suggests that itch symptoms have a localised character in this sample of patients with post-burn itch. For future studies, a biopsychological approach with integration of peripheral and central nervous system techniques, linear and non-linear EEG analysis, injured and non-injured stimulation sites, and incorporation of individual characteristics is recommended. Insight into pathophysiological mechanisms underlying chronic post-burn itch could improve diagnostics and treatments.

The Imbalance of MMP-2/TIMP-2 and MMP-9/TIMP-1 Contributes to Collagen Deposition Disorder in Diabetic Non-Injured Skin.

The importance of the early diagnosis and treatment of diabetes and its cutaneous complications has become increasingly recognized. When diabetic non-injured skin was stained with Masson’s trichrome, its dermal collagen was found to be disordered, its density was variable, and it was dispersed or arranged in vague fascicles. The collagen type I sequencing results of RNA sequencing-based transcriptome analysis of three primary human skin cell types—dermal fibroblasts, dermal microvascular endothelial cells, and epidermal keratinocytes—under high glucose were analyzed. The results showed that both COL1A1 and COL1A2 mRNA expressions were reduced in human dermal fibroblasts (HDFs). The ratio of matrix metalloproteinase (MMP)-2/tissue inhibitors of metalloproteinase (TIMP)-2 and MMP-9/TIMP-1 in HDFs increased when treated with high glucose. By inhibiting MMP-2 and MMP-9 with SB-3CT, collagen deposition disorder of the skin in streptozotocin-induced diabetes mice was alleviated. The imbalance of MMP2/TIMP2 and MMP9/TIMP1 contributes to the non-injured skin disorder of collagen deposition in diabetes, suggesting a possibility for early treatment of diabetes skin complications.

Critical Environmental Limits for Prolonged Work in the Heat Using a Simulated Burn Injury Model

Following a deep burn injury, excision of devitalized skin and subsequent grafting impair sweat production within grafted sites. Since the capacity for whole‐body evaporative heat dissipation is dependent on sweat production and the total non‐injured skin area available for heat dissipation, burn injuries likely reduce the capacity for whole‐body heat dissipation in proportion to the size of the burn injury during heat stress. To test this possibility, four healthy subjects (1 female; 28 ± 7 years, 71.1 ± 9.0 kg, 1.87 ± 0.12 m2) visited the laboratory on separate days to complete an incremental humidity protocol while cycling at a fixed metabolic heat production (5 W/kg, equivalent to ~35% maximum oxygen uptake) in 40°C with and without simulated burn injuries of 20%, 40%, or 60% of total body surface area. During each trial, exercise was performed at an initial relative humidity (RH) of 25% for 30 min to achieve thermal equilibrium, after which exercise continued as RH was increased by 3% every 5 min up to 90 min. A ‘critical’ RH was identified as the RH value above which a steady‐state esophageal temperature could no longer be maintained, thus providing an indication of maximum evaporative heat dissipation. Burn injuries were simulated by covering skin on the torso, arms, and legs with highly absorbent, vapor‐impermeable material that prevents sweat evaporation. The results show that the average critical RH declined with the size of the simulated burn injury up to 40% (0%: 44.1 ± 2.4%; 20%: 41.8 ± 2.3%; 40%: 31.4 ± 5.1%), with significant reductions in the critical RH at 40% vs. 0% and 20% simulated burn injuries (P=0.009). However, a critical RH value could not be discerned in one subject with a 40% simulated burn injury or in any subject with a 60% simulated burn injury, indicating physiologically uncompensable conditions throughout the experimental protocol. These preliminary data suggest that under the current environmental conditions, burn survivors with injuries of ≥40% have a substantially attenuated capacity for heat dissipation, placing them at greater risk of heat‐related illness during prolonged work and heat stress. Such information may be incorporated into exposure guidelines for burn survivors working under severe occupational heat stress such as military personnel.Support or Funding InformationFunding: Department of Defense – US Army, W81XWH‐15‐1‐0647This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

(150) - Silencing keratinocytes in a postoperative pain model

Acute postoperative pain is experienced by the majority who undergo surgery. In addition, mechanical and thermal hyperalgesia are observed at the site of incision. Treatments for postoperative pain are suboptimal and understanding the underlying mechanism of this acute pain is vital to developing improved treatments. Previous experiments have demonstrated that in non-injured skin, hyperpolarization of keratinocytes decreases baseline mechanical and heat sensitivity. However, it is unknown if keratinocytes play a role in mediating the mechanical and thermal hyperalgesia observed in a postoperative incision model. Here, we utilized optogenetics to assess whether silencing keratinocytes by means of hyperpolarization, would reduce post-incisional heat and mechanical hyperalgesia. Transgenic mice that selectively expressed Archaerhodopsin (Arch) in keratinocyte cell membranes were used as a model. A 5 mm incision was made through the skin and underlying plantar muscle. The ipsilateral paw was exposed to amber light, to activate Arch, or blue light (control). Mechanical and heat sensitivity were measured on the ipsilateral medial hind paw, using the von Frey mechanical assay and the Hargreaves heat assay, respectively. Measurements were collected daily, including 2-hours post-incision through 7 days post-incision. Despite all animals developing significant heat and mechanical hyperalgesia following incision, there was no significant difference in post-incision hyperalgesia following the hyperpolarization of keratinocytes. However, after 15 minutes of amber light exposure, a trend in decreased heat hyperalgesia emerged in days 4, 5 and 7. The data suggest that transient silencing of keratinocytes is not sufficient to significantly decrease the sensitization experienced in this post-incision model. As pain sensed by injury to the plantar muscle may be concealing the effects of silencing keratinocytes, future studies will isolate the incision to exclusively skin. Supported by a T35 training grant from the National Heart, Lung, and Blood Institute.

Diagnosis of Vitality in Skin Wounds in the Ligature Marks Resulting From Suicide Hanging.

Ascertaining the vital origin of skin wounds is one of the most challenging problems in forensic pathology. The forensic literature describes biomarkers and methods for differentiating vital and postmortem wounds, although no clear conclusions have been reached. The aim of this study was to characterize human vital wounds by analyzing the concentrations of metallic ions and the expression of P-selectin and cathepsin D in skin wounds in the ligature marks in a cohort of suicidal hangings for which vitality was previously demonstrated.A total of 71 skin wounds were analyzed within a postmortem interval of 19 to 36 hours. The concentration of Fe, Zn, Mg, and Ca and the expression of P-selectin and cathepsin D were analyzed together and separately. The majority of autopsied suicidal hangings were men (86%) with complete hanging mode (60.7%) in which there was a high frequency of subcutaneous injuries (78.3%). High concentrations of Ca and Mg compared with Fe and Zn were found. Ca and Zn concentrations decreased, and Fe concentration increased with the seriousness of the injury. A high percentage of moderately negative expression of both proteins was correlated with subcutaneous injury and low or medium concentrations of Fe.In conclusion, the joint study of metallic ions and proteins allows to characterize and to differentiate an injured vital wound of noninjured skin, especially when the damage in the tissue affects to the majority of the structures of the skin, but these results will need to be complemented with other biomarkers in time-controlled samples to further help in the differentiation of vital and postmortem wounds.

Sensory Neuron-Specific Deletion of TRPA1 Results in Mechanical Cutaneous Sensory Deficits

The nonselective cation channel transient receptor potential ankyrin 1 (TRPA1) is known to be a key contributor to both somatosensation and pain. Recent studies have implicated TRPA1 in additional physiologic functions and have also suggested that TRPA1 is expressed in nonneuronal tissues. Thus, it has become necessary to resolve the importance of TRPA1 expressed in primary sensory neurons, particularly since previous research has largely used global knock-out animals and chemical TRPA1 antagonists. We therefore sought to isolate the physiological relevance of TRPA1 specifically within sensory neurons. To accomplish this, we used Advillin-Cre mice, in which the promoter for Advillin is used to drive expression of Cre recombinase specifically within sensory neurons. These Advillin-Cre mice were crossed with Trpa1fl/fl mice to generate sensory neuron-specific Trpa1 knock-out mice. Here, we show that tissue-specific deletion of TRPA1 from sensory neurons produced strong deficits in behavioral sensitivity to mechanical stimulation, while sensitivity to cold and heat stimuli remained intact. The mechanical sensory deficit was incomplete compared to the mechanosensory impairment of TRPA1 global knock-out mice, in line with the incomplete (∼80%) elimination of TRPA1 from sensory neurons in the tissue-specific Advillin-Cre knock-out mice. Equivalent findings were observed in tissue-specific knock-out animals originating from two independently-generated Advillin-Cre lines. As such, our results show that sensory neuron TRPA1 is required for mechanical, but not cold, responsiveness in noninjured skin.

Role of integrin-linked kinase signaling pathway in skin lesions and wound healing in diabetic rats

Objective To investigate the role of integrin-linked kinase (ILK) signaling pathway in the skin lesions and wound healing in diabetic rats. Methods Thirty-six SD rats were divided into diabetic wound group (D) and non-diabetic wound group (N) according to the random number table, with 18 rats in each group. 10 g/L streptozocin (60 mg/kg) was intraperitoneally injected in rats in group D, while the rats in group N were given same quantity of sodium citrate buffer. Two weeks after successful reproduction of diabetic model of rats in group D, two full-thickness skin of an area of 2 cm×2 cm was resected on both sides of back of rats in the two groups. Wounds of three rats of each group were photographed and examined on post injury day (PID) 1, 3, 7, 10, 14, and 21, and the wound healing rates were calculated. The non-injured skin and wound tissue (central part) on back of three rats of the rest 15 rats in the two groups were harvested on PID 3, 7, 10, 14, and 21, respectively. Morphology of the non-injured skin tissue was observed with HE staining, and the thickness of full-thickness skin and epidermis were measured. The mRNA expression levels of ILK, protein kinase B (Akt), and glycogen synthase kinase-3β (GSK-3β) in non-injured skin tissue were determined with real-time fluorescent quantitative RT-PCR. The protein expression levels of ILK, Akt, phosphorylated Akt, GSK-3β, and phosphorylated GSK-3β in non-injured skin tissue, and ILK, phosphorylated Akt in wound tissue were assessed with Western blotting. Data were processed with two independent-sample t test, one-way analysis of variance, SNK test and analysis of variance of factorial design. Results (1) After injury, the wound scabs of rats in group N were dry, and red granulation tissue with no excretion were seen when the scabs fell off, and the wound healed fast. After injury, excretion under the wound scabs of rats in group D was seen, and the scabs easily fell off with exposure of pink granulation tissue with much excretion, and the wounds healed slowly. Except for PID 3, the wound healing rate of rats in group D was significantly lower than that in group N on other PIDs (with t values from 3.858 to 13.738, P 0.05). (4) From PID 3 to 21, the protein expression levels of ILK, Akt and phosphorylated Akt in non-injured skin tissue of rats in group D were significantly lower than those in group N (with t values from 2.630 to 6.209, P 0.05); the protein expression level of phosphorylated GSK-3β in non-injured skin tissue of rats in group D was significantly higher than that in group N (t=4.131, P 0.05), and the protein expression level of phosphorylated Akt in wound tissue was significantly higher than that in non-injured skin tissue (F=117.329, P 0.05), and the protein expression level of phosphorylated Akt in wound tissue was significantly higher than that in non-injured skin tissue (F=184.120, P<0.001). Conclusions The skin lesion of diabetic rats may be related to the declined expression levels of ILK, Akt and phosphorylated Akt in the ILK signaling pathway. The refractory healing of wound in diabetic rats may be related to the declined expression level of phosphorylated Akt. Key words: Diabetes mellitus; Skin; Wound healing; Integrin-linked kinase; Protein kinase B; Glycogen synthase kinase-3β

Foxn1 Transcription Factor Regulates Wound Healing of Skin through Promoting Epithelial-Mesenchymal Transition.

Transcription factors are key molecules that finely tune gene expression in response to injury. We focused on the role of a transcription factor, Foxn1, whose expression is limited to the skin and thymus epithelium. Our previous studies showed that Foxn1 inactivity in nude mice creates a pro-regenerative environment during skin wound healing. To explore the mechanistic role of Foxn1 in the skin wound healing process, we analyzed post-injured skin tissues from Foxn1::Egfp transgenic and C57BL/6 mice with Western Blotting, qRT-PCR, immunofluorescence and flow cytometric assays. Foxn1 expression in non-injured skin localized to the epidermis and hair follicles. Post-injured skin tissues showed an intense Foxn1-eGFP signal at the wound margin and in leading epithelial tongue, where it co-localized with keratin 16, a marker of activated keratinocytes. This data support the concept that suprabasal keratinocytes, expressing Foxn1, are key cells in the process of re-epithelialization. The occurrence of an epithelial-mesenchymal transition (EMT) was confirmed by high levels of Snail1 and Mmp-9 expression as well as through co-localization of vimentin/E-cadherin-positive cells in dermis tissue at four days post-wounding. Involvement of Foxn1 in the EMT process was verified by co-localization of Foxn1-eGFP cells with Snail1 in histological sections. Flow cytometric analysis showed the increase of double positive E-cadherin/N-cadherin cells within Foxn1-eGFP population of post-wounded skin cells isolates, which corroborated histological and gene expression analyses. Together, our findings indicate that Foxn1 acts as regulator of the skin wound healing process through engagement in re-epithelization and possible involvement in scar formation due to Foxn1 activity during the EMT process.

Immunohistochemical profile of stromal constituents and lymphoid cells over the course of wound healing in murine model.

To assess the evolution profile of the immunohistochemical expression of stromal constituents over the time-course of wound healing in a murine model. Surgical wounds were performed in the back of 24 Wistar rats. After three, seven, 14 and 21 days, six rats were euthanized and the wounded histologically processed to assess the immunohistochemical expression of CD3, CD20, CD31, α-SMA and type-I collagen. Non-injured skin samples (NSS) were used as control. Data were subjected to statistical analysis using ANOVA and Tukey test. The mean of CD3 and CD20 positive cells in the wounds was significantly higher than in NSS at seven and 14 days (p<0.001). The blood vessels content was significantly lower than in NSS (p<0.05) at three days, but increased at seven and 14 days (p<0.01). The mean of α-SMA positive cells at seven, 14 and 21 days was higher than in NSS (p<0.05). The relative content of type I collagen increased from three to 21 days, but remained lower than in NSS (p<0.05). Lymphoid cells, myofibroblasts and microvessels contents varied over the time-course of wound healing, with peak at seven days and progressive reduction until 21 days. The type I collagen content increased over time.

Selectivity of a bromelain based enzymatic debridement agent: A porcine study

BackgroundDebridement of the burn eschar is a cornerstone of burn wound care. Rapid enzymatic debridement with a bromelain-based agent (Debriding Gel Dressing-DGD) has recently been investigated. The current study was designed to further investigate the selectivity of DGD to burned eschar in a larger number and more varied types of wounds. MethodsA systematic animal experiment was conducted to determine the effects of DGD on normal, non-injured skin, burns, exposed dermis of donor sites, and skin punch biopsy wells. Partial thickness dermal burns and partial thickness skin graft donor sites were created on a pig and treated with a 4-h application of DGD or its control hydrating vehicle that does not have any activity except hydration. Punch biopsy samples were taken before and after treatment and microscopically assessed for evidence of tissue viability and its respective components thickness. ResultsRapid dissolution of the burn eschar was noted in all DGD but not vehicle treated burns. There was no apparent damage to the underlying sub eschar dermis, donor sites, normal skin or punch biopsy wells after exposure to DGD. While the thickness of the treated tissues slightly increased due to edema, the increase in dermal thickness was similar after treatment with DGD or its vehicle. The increase in the cross section surface area of the treated punch biopsy wells was similar after treatment with DGD and its control vehicle. ConclusionsExposure of the burn eschar to DGD results in its rapid dissolution. Exposure of normal skin or non-burned dermis to DGD has no effects demonstrating its selectivity to eschar.

IL-1beta in the trigeminal subnucleus caudalis contributes to extra-territorial allodynia/hyperalgesia following a trigeminal nerve injury

It has been reported that the whisker pad (WP) area, which is innervated by the second branch of the trigeminal nerve, shows allodynia/hyperalgesia following transection of the mental nerve (MN: the third branch of the trigeminal nerve). However, the mechanisms of this extra-territorial pain induction still remain unclear. Glia and cytokines are known to facilitate perception of noxious input, raising a possibility that these non-neuronal elements are involved in the induction and spread of allodynia/hyperalgesia at non-injured skin territory. One day after MN transection, tactile allodynia/hyperalgesia developed on the ipsilateral WP area, which is in the non-injured skin territory. The tactile allodynia/hyperalgesia lasted for more than 56 days. In response to MN transection, astrocytes and microglia appeared to be in an activated state, and interleukin (IL)-1beta was up-regulated in astrocytes in the trigeminal subnucleus caudalis (Vc). Allodynia/hyperalgesia at WP area induced by MN transection was attenuated dose-dependently by IL-1 receptor antagonist IL-1ra (i.t., 0.05, 0.5, and 5 pg/rat). Fos-like immunoreactive (Fos-Li) neurons were observed in the Vc after non-noxious mechanical stimulation of the WP area in the rats with MN transection. Administration of IL-1ra also attenuated the number of Fos-Li neurons dose-dependently. Administration of a noncompetitive antagonist of NMDA receptors MK-801 (i.t., 5 μg/rat) reversed allodynia/hyperalgesia. IL-1 receptor type I (IL-1RI) was localized in Fos- and phospho NR1-immunoreactive neurons. These results suggest that IL-1beta in the Vc plays an important role in the development of extra-territorial tactile allodynia/hyperalgesia after MN transection.

Injury Is a Major Inducer of Epidermal Innate Immune Responses during Wound Healing

We examined the importance of injury for the epidermal innate immune response in human skin wounds. We found that injury, independent of infiltrating inflammatory cells, generated prominent chemotactic activity toward neutrophils in injured skin because of IL-8 production. Furthermore, injury was a major inducer of the expression of antimicrobial (poly)peptides (AMPs) in skin wounds. In human skin, these injury-induced innate immune responses were mediated by activation of the epidermal growth factor receptor (EGFR). Consequently, inhibition of the EGFR blocked both the chemotactic activity generated in injured skin and the expression of the majority of the AMPs. The importance of injury was confirmed in mouse experiments in vivo, in which injury independent of infection was a potent inducer of AMPs in skin wounds. To our knowledge, these data thereby provide a previously unreported molecular link between injury and neutrophil accumulation and identify the molecular background for the vast expression of IL-8 and AMPs in wounded epidermis. Conceptually, these data show that the growth factor response elicited by injury is important for the recruitment of neutrophils in skin wounds.

To Heal or Not to Heal: Predictive Value of In Vivo Reflectance-Mode Confocal Microscopy in Assessing Healing Course of Human Burn Wounds

The purpose of this study was to assess if the healing course of burn wounds of indeterminate depth can be predicted based on serial in vivo reflectance-mode confocal microscopy (RMCM) analysis. Twenty-four patients (mean age, 33.1+/-11.4 years; mean burn size: 6% TBSA) were investigated at 12, 36, and 72 hours after burn of indeterminate depth and retrospectively grouped into healing group (HG: 16 patients) and nonhealing group (NHG: eight patients). Noninjured skin served as controls. The following parameters were assessed: quantitative blood cell flow (BCF), basal layer thickness (BLT), and inflammatory cells. At 12 hours postburn, BCF increased to 101.67+/-7.64 cells/min in HG vs 85+/-50 cells/min in NHG compared with controls (56.5+/-2.3 cells/min). At 36 and 72 hours, BCF increased to 115+/-10 cells/min and 125+/-50 cells/min in HG vs decreased to 80+/-5 cell/min and 75+/-5 cells/min in NHG (P<.05). At 12 hours postburn, BLT increased to 19.43+/-0.93 microm in HG vs 29+/-1 microm in NHG compared with controls (15.40+/-0.60 microm, P<.05). In HG, further gradual increase of BLT to 20+/-1 microm (36 hours) and 21+/-1 microm (72 hours) was observed, whereas BLT was destroyed after 36 hours in NHG. Qualitative assessment found insignificant amount of IC in controls and low amount in HG until 72 hours postburn, whereas progressive increase in IC from low amount (12 hours) to numerous (36 hours) and massive (72 hours) was observed in NHG. RMCM enables simultaneous evaluation of microcirculation, histomorphology, and inflammatory cell trafficking in burn wounds. RMCM may help to predict whether burns of indeterminate depth have the potential to heal and can be a valuable tool to clinicians to guide early therapeutic decision-making process in burn patients.

Sustained impairments in cutaneous vasodilation and sweating in grafted skin following long-term recovery.

We previously identified impaired cutaneous vasodilation and sweating in grafted skin 5 to 9 months postsurgery. The aim of this investigation was to test the hypothesis that cutaneous vasodilation, but not sweating, is restored as the graft heals. Skin blood flow and sweat rate were assessed from grafted skin and adjacent noninjured skin in three groups of subjects: 5 to 9 months postsurgery (n=13), 2 to 3 years postsurgery (n=13), and 4 to 8 years postsurgery (n=13) during three separate protocols: 1) whole-body heating and cooling, 2) local administration of vasoactive drugs, and 3) local heating and cooling. Cutaneous vasodilation and sweating during whole-body heating were significantly lower (P<.001) in grafted skin when compared with noninjured skin across all groups and demonstrated no improvements with recovery time postsurgery. Maximal endothelial-dependent (acetylcholine) and endothelial-independent (sodium nitroprusside) cutaneous vasodilation remained attenuated (P<.001) in grafted skin up to 4 to 8 years postsurgery, indicating postsynaptic impairments. In grafted skin, cutaneous vasoconstriction during whole-body and local cooling was preserved, whereas vasodilation to local heating was impaired, regardless of the duration postsurgery. Split-thickness skin grafts have impaired cutaneous vasodilation and sweating up to 4 to 8 years postsurgery, thereby limiting the capability of this skin's contribution to thermoregulation during a heats stress. In contrast, grafted skin has preserved vasoconstrictor capacity.

Incorrect Acticoat application causing iatrogenic injury to a child with a palmar burn

Acticoat (Smith and Nephew, Melbourne, Vic., Australia) is a nanocrystaline silver dressing which has broad spectrum antimicrobial and anti-inflammatory actions. This dressing must first be moistened with sterile water to become effective. Acticoat has been shown to significantly reduce the need for skin grafting in children with partial thickness burns and we recommend its use in the ED setting. Iatrogenic injury caused by the incorrect application of Acticoat to palmar burns is seen frequently in our Burns Clinic. This letter highlights a recent case and we provide recommendations for the prevention of this injury. A 9-month-old boy presented to the Royal Children’s Hospital Outpatient Burns Clinic, Melbourne, Australia, 3 days after sustaining a partial thickness contact burn to his left palm. The initial injury was confined to the hypothenar eminence. He was first seen in an ED where Acticoat was applied (Fig. 1). Saturated circumferential applications of Acticoat and an overlying plastic wrap resulted in maceration of the entire hand and interdigital shearing (Fig. 2). To protect non-injured skin when dressing hand burns with Acticoat, we recommend that: 1. Acticoat should be moistened with sterile water, but not dripping wet. 2. Acticoat and overlying occlusive dressings should not extend further than 1 cm beyond burn margins (Fig. 3). 3. Digits must first be separated before the hand is bandaged (Fig. 4). EDs play a vital role in treating the vast majority of partial thickness burn injuries. Knowledge of the

SKIN NITRIC OXIDE AND ITS METABOLITES ARE INCREASE IN NON-BURNED SKIN AFTER THERMAL INJURIES

Local and systemic inflammation can lead to progression of burn wounds, converting second- to third-degree wounds or extending the burn to adjacent areas. Previous studies have suggested that the skin is an important site of production of nitric oxide (NO), synthesized by inducible nitric oxide synthase (iNOS) activation after injury. NO increases in burned wounds, but its formation in noninjured skin has not been investigated. We hypothesized that after severe burns, NO and cytotoxic peroxynitrite would increase in noninjured skin. We also tested the hypothesis that BBS-2, a specific inhibitor of iNOS, would impair NO formation after burn. Thirteen female sheep were randomized into burn injury and smoke inhalation (n = 5, group 1), burn and smoke treated with BBS-2 (n = 3, group 2), and sham (saline treatment, no injury) (n = 5, group 3). All the animals, including the sham-injury group, were mechanically ventilated for 48 h. Samples of nonburned skin and plasma were collected from each animal, and levels of NO and its metabolites were evaluated using a NO chemiluminescent detector. Nitrotyrosine and iNOS expression were determined in the skin by Immunoperoxidase staining, and scoring of masked slides (epidermis, hair follicles, vessels, glands, and stroma) was performed. Skin NO and metabolites significantly increased in the burn and smoke injury group, and this was inhibited by BBS-2. Nitrotyrosine expression also increased significantly in the skin of burned animals. BBS-2 prevented the increase of NOx but not the increase of nitrotyrosine expression in skin. Plasma levels of NO increased in burned animals when compared with sham, but this increase was not significant. The increase of NO and its metabolites after burn in noninjured skin is followed by a significant increase in peroxynitrite, a potent cytotoxic mediator.

Expression of intracellular filament, collagen, and collagenase genes in diabetic and normal skin after injury

Reports have shown differences in gene expression in the skin of diabetic and normal mice both at baseline and after injury. Cluster analysis identified distinct expression patterns within intermediate filaments and extracellular proteins. This report addresses the effect of diabetes and injury on the expression of keratin-associated proteins, keratin complexes, procollagen, and collagenase (matrix metalloproteinase; MMP) genes. At baseline keratin-associated proteins and keratin complexes gene expression was increased in diabetic mice. After surgery, the level of expression for keratin-associated proteins and keratin complexes genes decreased in diabetic mice, but did not change in normal mice. If the expression of a procollagen gene differed between diabetic and normal mice, the expression was lower in diabetic mice. Procollagen gene expression was elevated after skin excision compared with noninjured skin. At baseline, the level of MMP and tissue inhibitor of metalloproteinase gene expression was comparable between mouse strains. With injury, the expression of several MMP genes was increased in both mouse strains, but to higher levels in diabetic mice. At day 7, the level of MMP-9 activity in granulation tissue was elevated. This alteration may contribute to delayed healing in diabetic mice. Therefore, differences in gene expression exist between mouse strains and can assist in understanding of physiological manifestations, including delayed healing, in diabetic mice.