Update on pruritic mechanisms of hypertrophic scars in postburn patients: the potential role of opioids and their receptors

Histamine H1 receptor antagonist attenuates catecholamine surge and organ injury after severe burns

Severe burns induce a catecholamine surge, causing severe damage to the organism and raising the possibility of multisystem organ failure. Few strategies are generally acceptable to reduce catecholamine surge and organ injury post-burn. We have previously shown that histamine can amplify the catecholamine surge. In addition, promethazine, a first-generation histamine H1 receptor antagonist, alleviates catecholamine surge and organ injury after severe burns in rats. However, evidence is lacking on whether promethazine benefits patients after severe burns. Currently, sedation and analgesia (such as midazolam and fentanyl) are commonly required for patients after severe burns. It remains unclear if patients after severe burns derive clinical benefit from histamine H1 receptor antagonists combined with sedation and analgesia. This study investigates the therapeutic effect of promethazine on patients after severe burns. Moreover, we test the therapeutic effect of cetirizine, a second-generation histamine H1 receptor antagonist, combined with sedation and analgesia in rats after severe burns. We find that promethazine-pethidine treatment shows a tendency for a lower level of total bilirubin than midazolam-fentanyl in patients 7-day after severe burn. Our study confirms that cetirizine combined with midazolam and fentanyl reduces catecholamine surge and liver and lung damage after severe burns in rats; the effects are better than midazolam and fentanyl treatment. In summary, for the first time, we suggest that histamine H1 receptor antagonist has the potential clinical value of reducing liver injury in patients after severe burns. In addition, we reveal that cetirizine combined with midazolam and fentanyl may be an ideal strategy for treating severe burns.

Immunohistochemical Analysis of Postburn Scars following Treatment Using Dermal Substitutes

Background

Post-burn hypertrophic scars commonly occur after burns. Studies that compare dermal substitutes with other treatment methods are insufficient. The purpose was to analyze the histopathological differences in hypertrophic burn scars after Matriderm®+split-thickness skin graft (STSG) and compare with AlloDerm®+STSG, STSG, full-thickness skin graft (FTSG), and normal skin.

Methods

Samples of unburned, normal skin and deep 2^nd or 3^rd degree burns were obtained from patients who experienced a burn injury in the past to at least 6 months before biopsy, which was performed between 2011 and 2012. All subjects received >6 months of treatment before the biopsy. Intervention groups were normal (63), STSG (28), FTSG (6), Matriderm® (11), and AlloDerm® (18). Immunohistochemical analyses of elastin, collagen I, collagen III, cluster of differentiation 31 (CD31), smooth muscle actin (α-SMA), and laminin from scar and control tissues were performed and compared.

Results

α-SMA vascular quantity and vessel width, stromal CD31, and basement membrane laminin expression were not significantly different between normal and intervention groups. Matriderm® group showed no significant difference in elastin, collagen III, stromal CD31 and α-SMA, CD31 vessel width, stromal α-SMA, vessel quantity and width, and laminin length compared to the normal group, meaning they were not significantly different from the normal skin traits.

Conclusion

Dermal substitutes may be an optimal alternative to address the cosmetic and functional limitations posed by other treatment methods.

Low dose naloxone for pruritus in systemic sclerosis: Case series and literature review

RATIONALE

Pruritus is a common symptom in patients with systemic sclerosis and has a tremendous effect on the quality of life. Nevertheless, current therapeutic options are limited. The pathogenesis of pruritus in systemic sclerosis is not completely understood; however, opiate-mediated neurotransmission has been postulated to be involved.

PATIENT CONCERNS AND DIAGNOSIS

We describe 4 female patients with systemic sclerosis suffering from severe pruritus, with an average 5D-itch score of 22.75.

INTERVENTION AND OUTCOMES

Low-dose oral naloxone was initiated, followed by a significant improvement in the level of pruritus, reaching an average 5D-itch score of 7.5, after 6 and 12 months of treatment. None of the patients experienced side effects.

LESSONS

Low-dose naloxone plays an important role in the management of pruritus in systemic sclerosis.

Pruritus in Keloid Scars: Mechanisms and Treatments

Keloids are scars that extend beyond the margins of an insulting cutaneous injury. Keloids are often thought to be primarily a cosmetic issue, as they are typically quite raised and pigmented. However, these scars also present with functional symptoms of pruritus and pain that significantly impact quality of life. The symptom of pruritus is frequently overlooked by dermatologists, and treatments are often primarily focused on the gross appearance of the scar. This review describes the prevalence and importance of pruritus in keloids. In addition, the putative mechanisms underlying the development of keloid pruritus, which include neuronal and immunological mechanisms, are discussed. Furthermore, this review describes keloid treatments that have been shown to reduce pruritus, treatments that specifically target the itch, and emerging therapies.

Synergic Effect of Botulinum Toxin Type A and Triamcinolone Alleviates Scar Pruritus by Modulating Epidermal Hyperinnervation: A Preliminary Report

BACKGROUND

Patients often experience scar-related pruritus, which adversely affects quality of life. Triamcinolone acetonide (TAC) is widely used to treat pathologic scars, and botulinum toxin type A (BTX-A) reportedly improves scarring and associated discomfort.

OBJECTIVES

The aim of this study was to investigate the clinical efficacy of combining TAC and BTX-A to reduce scar itch; potential mechanisms were investigated via an animal model.

METHODS

For the clinical study, each scar on a patient was divided into 2 equal parts, with one part receiving TAC/BTX-A and the other TAC alone. Therapeutic interventions were administered over 3 sessions at 4-week intervals. Itch intensity was measured on a visual analog scale before each therapeutic intervention (V1, V2, V3) and 4 weeks after the last intervention (V4). For the animal model, rats were allocated into 5 groups: control, untreated burn, TAC, BTX-A, and TAC/BTX-A. We evaluated alloknesis in the right hind paw and analyzed possible molecular mechanisms.

RESULTS

In humans, TAC/BTX-A significantly reduced scar itch compared with TAC alone at V4 (P = 0.04). In rats, post-burn itch was mitigated at 4 weeks after treatment with TAC, BTX-A, and TAC/BTX-A (P = 0.03, P = 0.0054, and P = 0.0053, respectively). TAC/BTX-A significantly decreased the density of intraepidermal nerve fibers post-burn relative to the untreated burn (P = 0.0008). TAC/BTX-A downregulated the expressions of nerve growth factor and protein transient receptor potential vanilloid subtype 1.

CONCLUSIONS

TAC/BTX-A therapy exhibited enhanced and sustained clinical efficacy in relieving scar itch, possibly via modulating epidermal innervation and expression of transient receptor potential vanilloid subtype 1 .

LEVEL OF EVIDENCE: 2

Doxepin cream is not effective in reducing itch in burn scar patients: A multicenter triple-blind randomized clinical crossover trial

OBJECTIVE

To evaluate the effect of doxepin hydrochloride 5% cream on reducing pruritus in burn scar patients compared to a placebo cream.

METHOD

We conducted a multicenter triple-blind randomized clinical placebo-controlled crossover trial in which burn patients ≥18 years with an itch intensity ≥3 on a Visual Analogue Scale (VAS) were randomized between a doxepin-placebo or placebo-doxepin treatment protocol. Patients used each cream during two weeks with a wash-out period of one week in between. Primary outcome was change in itch intensity in two weeks' time using the VAS. Secondary outcome included the impact of itch (Burn Itch Questionnaire). Other parameters were the use of hydrating cream, silicon treatment, pressure garments, and other antipruritic medication.

RESULTS

Twenty-seven patients were included. The change in itch intensity (VAS) was not different during the doxepin and placebo period (p=0.994); neither the doxepin cream nor placebo cream reduced itch intensity. However, based on the Burn Itch Questionnaire, we observed a statistically significant decrease in itch intensity and improvement in impact scores in both treatment groups, but no difference in the degree of reduction between the groups.

CONCLUSION

Doxepin cream was not effective in reducing pruritus in our burn patient study population.

Efficacy of acupuncture in treating scars following tissue trauma

INTRODUCTION

Anecdotally, acupuncture is used in the treatment of scar tissue in order to improve scar quality and reduce symptoms of pain and pruritus. Unlike conditions such as lower back pain, knee osteoarthritis and migraines, there are no systematic reviews to confirm treatment efficacy. This systematic literature review aims to assess the current level of evidence for the use of acupuncture for treating abnormal scars such as hypertrophic or other symptomatic scars.

METHODS

A comprehensive database search was performed followed by reviewing reference lists, grey literature databases and Google Scholar. Study quality was assessed using the Oregon CONSORT STRICTA instrument (OCSI) for clinical trials and the Joanna Briggs Institute (JBI) checklist for case reports.

RESULTS

The search strategy discovered five case studies, one retrospective cohort study, one cohort study and three clinical trials that investigated the use of acupuncture for scars. Studies rated as low to moderate quality (26-50%) on the OCSI checklist due to lack of detailed reporting, use of non-validated outcome measures and heterogeneity of participant cohorts. Three case studies rated as moderate quality (5-6/8) and two as low quality (<2/8) on the JBI checklist.

DISCUSSION

All studies reported positive outcomes for the use of acupuncture for scar symptoms; however, treatment frequency, duration, number of treatments and points used varied between studies.

CONCLUSION

Acupuncture for the treatment of abnormal scars has a low level of evidence thus requiring further well-designed, controlled trials to be performed. Recommended treatment protocols for future studies have been provided.

Cultural adaptation of the 5-D itch scale and its reliability for Brazilian burn survivors

This was a methodological study whose objective was to culturally adapt the 5-D itch scale for Brazilian Portuguese and verify its practicability, acceptability and reliability for burn survivors. This study followed the five internationally recommended steps for the adaptation process: translation, synthesis, back translation, assessment by an expert committee and pretesting process; besides, an evaluation of its practicability, acceptability and reliability was conducted. The pretest was carried out with thirty burn survivors - hospitalized or on outpatient follow-up - from two public hospitals in the state of São Paulo. Most burn survivors were male (18; 60%), aged at mean of 39.2 (SD=11.1), with deep partial burn injuries (16; 59.3%), percentage of total burn surface area of 12.3 (SD=9.8); and most accidents occurred at domestic environment (18; 60%). The Brazilian version had semantic and idiomatic, conceptual and cultural equivalences, with a satisfactory content validity index for each item (CVI-I). Mean application time was 3.5minutes, acceptability was good, and there was evidence of reliability for the total score (0.793). The Brazilian version of the 5-D itch scale showed equivalence and evidence of reliability for assessing pruritus and its impact in burn survivors.

Medical Needling: Effect on Moisture and Transepidermal Water Loss of Mature Hypertrophic Burn Scars

Background: Burn scars remain a serious psychological and physiological problem for affected people. Clinical studies and scientific research have already shown that medical needling improves the scar quality in terms of skin elasticity and erythema. At the same time, patients are confronted with a low-risk therapy and face comparatively less postoperative complications.

Objective: The goal of our study was to examine the influence of medical needling on the skin moisture and transepidermal water loss (TEWL) of hypertrophic dry scars. Therefore, 20 patients, of an average age of 34.63 years, with deep second- and third-degree burn scars have been treated.

Methods: Medical needling is performed using a roller covered with needles of 3-mm length. The needling device is rolled over the scar in three directions: vertically, horizontally, and diagonally in order to create as many puncture channels as possible. The puncturing leads to multiple micro-wounds and intradermal bleeding, which evokes the post-needling regeneration cascade. The patients were followed up for 12 months postoperatively. The results have been evaluated by means of objective as well as subjective measurement methods.

Results: The objective measures show that medical needling influences epidermal thickness and improves the epidermal barrier function at a molecular level. Outcomes are marked by a measurable increase in skin moisture and a reduction in TEWL.

Conclusion: Medical needling seems to be a promising approach for the treatment of mature hypertrophic burn scars with a focus on skin moisture and TEWL.

An in-situ forming skin substitute improves healing outcome in a hypertrophic scar model

Wound repair requires a sequential series of biological events that begins with the deposition of a temporary scaffold within which cells can repair the skin. Without a scaffold, repair is essentially impossible. Aberrant wound healing, such as hypertrophic scarring or nonhealing, has a tremendous burden on healthcare and quality of life. Timely wound closure dramatically reduces the risk of infection and scarring. Cellular skin substitutes are opportune to meet this need. Our goal was to create an in-situ forming scaffold that can be easily combined with cells to rapidly form a dermal substitute within the wound bed. In this study, we evaluated the application of a polyvinyl alcohol-collagen-glycosaminoglycan-based biohybrid scaffold system in full-thickness wounds on a rabbit fibrotic ear model. Punch wounds (6 mm) were either untreated or filled with an acellular scaffold, a scaffold containing xenofibroblasts, or a scaffold containing xenofibroblasts expressing indoleamine 2,3-dioxygenase (IDO). Results demonstrated that (1) both acellular and IDO-expressing fibroblast in-situ forming scaffolds significantly reduced scar elevation index (1.24±0.05 and 1.25±0.03; p<0.05) and improved overall healing quality compared with xenofibroblast scaffolds and untreated wounds; (2) IDO-expressing fibroblast scaffolds significantly reduced T-cell infiltration into the scaffold-engrafted area (p<0.05); and (3) both IDO-expressing and acellular in-situ forming scaffolds demonstrated increased vessel-like and nerve-like structures (p<0.05). The results demonstrated that the use of the in-situ forming scaffold, and even more so when delivering IDO-expressing cells, improved healing outcome in full-thickness hypertrophic rabbit ear wounds.

Update on hypertrophic scar treatment

Scar formation is a consequence of the wound healing process that occurs when body tissues are damaged by a physical injury. Hypertrophic scars and keloids are pathological scars resulting from abnormal responses to trauma and can be itchy and painful, causing serious functional and cosmetic disability. The current review will focus on the definition of hypertrophic scars, distinguishing them from keloids and on the various methods for treating hypertrophic scarring that have been described in the literature, including treatments with clearly proven efficiency and therapies with doubtful benefits. Numerous methods have been described for the treatment of abnormal scars, but to date, the optimal treatment method has not been established. This review will explore the differences between different types of nonsurgical management of hypertrophic scars, focusing on the indications, uses, mechanisms of action, associations and efficacies of the following therapies: silicone, pressure garments, onion extract, intralesional corticoid injections and bleomycin.