Genetic influence on scar height and pliability after burn injury in individuals of European ancestry: A prospective cohort study

Genetic influence on scar vascularity after burn injury in individuals of European ancestry: A prospective cohort study

After burn injury there is considerable variation in scar outcome, partially due to genetic factors. Scar vascularity is one characteristic that varies between individuals, and this study aimed to identify genetic variants contributing to different scar vascularity outcomes. An exome-wide array association study and gene pathway analysis was performed on a prospective cohort of 665 patients of European ancestry treated for burn injury, using their scar vascularity (SV) sub-score, part of the modified Vancouver Scar Scale (mVSS), as an outcome measure. DNA was genotyped using the Infinium HumanCoreExome-24 BeadChip, imputed to the Haplotype Reference Consortium panel. Associations between genetic variants (single nucleotide polymorphisms) and SV were estimated using an additive genetic model adjusting for sex, age, % total body surface area and number of surgical procedures, utilising linear and multinomial logistic regression. No individual genetic variants achieved the cut-off threshold for significance. Gene sets were also analysed using the Functional Mapping and Annotation (FUMA) platform, in which biological processes indirectly related to angiogenesis were significantly represented. This study suggests that SNPs in genes associated with angiogenesis may influence SV, but further studies with larger datasets are essential to validate these findings.

Scar Management and Dyschromia: A Summary Report from the 2021 American Burn Association State of the Science Meeting

Burn scars, and in particular, hypertrophic scars, are a challenging yet common outcome for survivors of burn injuries. In 2021, the American Burn Association brought together experts in burn care and research to discuss critical topics related to burns, including burn scars, at its State of the Science conference. Clinicians and researchers with burn scar expertise, as well as burn patients, industry representatives, and other interested stakeholders met to discuss issues related to burn scars and discuss priorities for future burn scar research. The various preventative strategies and treatment modalities currently utilized for burn scars were discussed, including relatively noninvasive therapies such as massage, compression, and silicone sheeting, as well as medical interventions such as corticosteroid injection and laser therapies. A common theme that emerged is that the efficacy of current therapies for specific patient populations is not clear, and further research is needed to improve upon these treatments and develop more effective strategies to suppress scar formation. This will necessitate quantitative analyses of outcomes and would benefit from creation of scar biobanks and shared data resources. In addition, outcomes of importance to patients, such as scar dyschromia, must be given greater attention by clinicians and researchers to improve overall quality of life in burn survivors. Herein we summarize the main topics of discussion from this meeting and offer recommendations for areas where further research and development are needed.

A Scoping Review of the Methodology Used in Studies of Genetic Influences on the Development of Keloid or Hypertrophic Scarring in Adults and Children After Acute Wounding

Significance: Keloid and hypertrophic scarring are common following acute wounds. However, the variability in scarring outcomes between individuals and in particular, the association between genetic factors and scarring, is not well understood. This scoping review aims to summarize the methodology used in studies of genetic influences on the development of keloid or hypertrophic scarring in adults and children after acute wounding. The objectives were to determine the study designs used, the characteristics of participants included, the tools used to assess scarring and the length of follow-up after wounding. Recent Advances: The review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Medline, Excerpta Medica Database (EMBASE), Web of Science, Biosciences Information Service (BIOSIS), Prospective Register of Systematic Reviews (PROSPERO), The Human Genetic Epidemiology (HuGE) Navigator (database of genetic association studies), and the genome-wide association study Catalog were searched from January 2008 to April 2020. Cohort studies and case-control studies that examined the association between one or more genetic variations and the development of keloid or hypertrophic scarring were eligible for inclusion. A narrative synthesis that grouped studies by wound type was conducted. Critical Issues: Nine studies met the inclusion criteria (five in burns, four surgical wounds, and none in other types of acute wounds). Seven assessed hypertrophic scarring, one keloid scarring, and one both scar types. Seven studies used a prospective cohort design. All studies used subjective methods (clinician or patient observation) to assess scarring. There was considerable variation in how scar scales were operationalized. Future Directions: This review identified a small body of evidence on genetic susceptibility to scarring after acute wounding. Further studies are needed, and in a wide range of populations, including patients with wounds caused by trauma.

Genomics of Human Fibrotic Diseases: Disordered Wound Healing Response

Fibrotic disease, which is implicated in almost half of all deaths worldwide, is the result of an uncontrolled wound healing response to injury in which tissue is replaced by deposition of excess extracellular matrix, leading to fibrosis and loss of organ function. A plethora of genome-wide association studies, microarrays, exome sequencing studies, DNA methylation arrays, next-generation sequencing, and profiling of noncoding RNAs have been performed in patient-derived fibrotic tissue, with the shared goal of utilizing genomics to identify the transcriptional networks and biological pathways underlying the development of fibrotic diseases. In this review, we discuss fibrosing disorders of the skin, liver, kidney, lung, and heart, systematically (1) characterizing the initial acute injury that drives unresolved inflammation, (2) identifying genomic studies that have defined the pathologic gene changes leading to excess matrix deposition and fibrogenesis, and (3) summarizing therapies targeting pro-fibrotic genes and networks identified in the genomic studies. Ultimately, successful bench-to-bedside translation of observations from genomic studies will result in the development of novel anti-fibrotic therapeutics that improve functional quality of life for patients and decrease mortality from fibrotic diseases.

Correlation Between the Warrior/Worrier Gene on Post Burn Pruritus and Scarring: A Prospective Cohort Study

INTRODUCTION

Associations between genetic variation and clinical conditions suggest that single nucleotide polymorphisms (SNPs) might correlate with postburn outcomes. COMT modulates catecholamine metabolism, and polymorphisms within the rs4680 allele result in variable enzyme activity. Catecholamines are known to modulate the inflammatory process and may affect scar formation. The aim of this study was to determine whether variants in the rs4680 SNP of the COMT gene are associated with post-burn pruritus and scarring.

METHODS

Adult burn patients, admitted between 2007 and 2017, with deep partial-thickness burns or delayed healing provided blood samples for genotyping and self-reported itch scores within 1 year of injury. Scarring was measured using the Vancouver Scar Scale (VSS). Itch scores ≥4 and VSS scores >7 were considered severe. Genomic deoxyribonucleic acid was genotyped for the rs4680 SNP using realtime polymerase chain reaction (PCR).

RESULTS

Median itch and VSS scores were highest for GG homozygotes and lowest for AA homozygotes. This difference was statistically significant for VSS score (P < 0.0001) and approached significance for itch (P = 0.052). After accounting for confounding variables, including race/ethnicity, age, sex, and burn size, the GG homozygotes demonstrated worse scarring (odds ratio 1.88, P = 0.005) compared to AG heterozygotes whereas the AA homozygotes trended towards a protective effect against scarring (odds ratio 0.71, P = 0.10). Itch did not demonstrate a statistically significant difference between rs4680 genotype.

CONCLUSIONS

Our analysis identifies a trend between COMT genotype with scarring, with rs4680 genetic variation constituting an independent risk factor for VSS score.

A Novel, Reliable Protocol to Objectively Assess Scar Stiffness Using Shear Wave Elastography

The aim of this research was to investigate the use of shear wave elastography as a novel tool to quantify and visualize scar stiffness after a burn. Increased scar stiffness is indicative of pathologic scarring which is associated with persistent pain, chronic itch and restricted range of movement. Fifty-five participants with a total of 96 scars and 69 contralateral normal skin sites were evaluated. A unique protocol was developed to enable imaging of the raised and uneven burn scars. Intra-rater and inter-rater reliability was excellent (intra-class correlation coefficient >0.97), and test-retest reliability was good (intra-class correlation coefficient >0.85). Shear wave elastography was able to differentiate between normal skin, pathologic scars and non-pathologic scars, with preliminary cutoff values identified. Significant correlations were found between shear wave velocity and subjective clinical scar assessment (r = 0.66). Shear wave elastography was able to provide unique information associated with pathologic scarring and shows promise as a clinical assessment and research tool.