Development and validation of a gene expression test to identify hard-to-heal chronic venous leg ulcers

Abstract

Background Chronic venous leg ulcers pose a significant burden to healthcare systems, and predicting wound healing is challenging. The aim of this study was to develop a genetic test to evaluate the propensity of a chronic ulcer to heal. Methods Sequential refinement and testing of a gene expression signature was conducted using three distinct cohorts of human wound tissue. The expression of candidate genes was screened using a cohort of acute and chronic wound tissue and normal skin with quantitative transcript analysis. Genes showing significant expression differences were combined and examined, using receiver operating characteristic (ROC) curve analysis, in a controlled prospective study of patients with venous leg ulcers. A refined gene signature was evaluated using a prospective, blinded study of consecutive patients with venous ulcers. Results The initial gene signature, comprising 25 genes, could identify the outcome (healing versus non‐healing) of chronic venous leg ulcers (area under the curve (AUC) 0·84, 95 per cent c.i. 0·73 to 0·94). Subsequent refinement resulted in a final 14‐gene signature (WD14), which performed equally well (AUC 0·88, 0·80 to 0·97). When examined in a prospective blinded study, the WD14 signature could also identify wounds likely to demonstrate signs of healing (AUC 0·73, 0·62 to 0·84). Conclusion A gene signature can identify people with chronic venous leg ulcers that are unlikely to heal.

Why Venous Leg Ulcers Have Difficulty Healing: Overview on Pathophysiology, Clinical Consequences, and Treatment

“…Currently, it is unclear if genetic alterations in a number of identified genes are causal or associations. Certainly, this area of research is interesting and requires further study in larger population-based studies and determination that early intervention in identified and affected individuals with specific venous gene polymorphic variants would benefit from interventions to correct venous hemodynamics and prevent VLU formation [180][181][182][183][184]. Important principles to prevent and reduce recurrent VLU are following adopted principles of timely referral to a vascular specialist, evaluation and ultrasonography, treating infection and debridement, appropriate compression, and appropriate interventions when indicated [1].…”

Sensitivity of the Wound Edge Gene Signature “WD14” in Responding to Clinical Change: A Longitudinal Cohort Study

“…The WD14 gene signature was created using three cohorts of patients: screening, validation and study cohorts (ethical approval numbers: 04/WSE02/10; SJT/C617/08; 09/WSE02/51). 11 A longitudinal cohort study was performed comprising of 85 consecutive patients referred to a tertiary wound healing unit, as previously described by Bosanquet et al in 2012 and therefore the methods will be only briefly reviewed herein. 12 Patients with chronic wounds consistent with underlying venous disease were diagnosed by a senior wound healing physician at a tertiary wound healing centre.…”

“…The methods used in genetic analysis have been described in detail previously. 11 Patients in the study cohort had their VLU wound edge biopsy WD14 gene signature score calculated and dichotomised into a 'healing' or 'non-healing' genotype at baseline. After 12 weeks, wounds were clinically assessed and classified as 'healing' if there was a reduction in wound size or 'non-healing' if they were static or deteriorating.…”

“…10 The WounD14 (WD14) gene signature was recently developed for use in predicting hard-to-heal chronic venous leg ulcers (VLU). 11 Wound edge biopsies were interrogated, and differences in expression of 14 genes were combined to a single score, which was able to predict wound healing outcome at three months with a sensitivity of 61.4% and a specificity of 85.4%. 11 The development of this tool only looked at a single biopsy, taken from a patient at a single time point, with follow up at 12 weeks, and it is not known if and how WD14 gene signature responds to wound healing changes over time.…”

“…11 Wound edge biopsies were interrogated, and differences in expression of 14 genes were combined to a single score, which was able to predict wound healing outcome at three months with a sensitivity of 61.4% and a specificity of 85.4%. 11 The development of this tool only looked at a single biopsy, taken from a patient at a single time point, with follow up at 12 weeks, and it is not known if and how WD14 gene signature responds to wound healing changes over time. The aim of this pilot study is therefore to evaluate if changes in the clinical healing status of patients' wounds are identified by the WD14 gene signature.…”