Influence of the Human Leukocyte Antigen Complex on the Development of Cutaneous Fibrosis: An Immunogenetic Perspective
Sara M. McCarty, Farhatullah Syed, Ardeshir Bayat
A number of aesthetically and physically distressing
disorders of the skin come under the general term "cutaneous fibrosis", all sharing a common abnormal wound healing process. These disorders are often incurable and effective treatments remain to be established and, as such, they present a significant burden for patients and a therapeutic challenge for clinicians. The aim of this review is to investigate the evidence of either positive or negative associations of the human leukocyte antigen (HLA) system with various types of cutaneous fibrosis, focussing in particular on keloid scars, hypertrophic scars and scleroderma. A standard systematic literature search was performed. The strengths and limitations of studies were evaluated in terms of significance, methodology and reproducibility. There is a clear association between specific HLA alleles and predilection or protection to cutaneous fibrosis. Of these candidate HLA alleles, the class II loci seem to be the most promising in terms of a genetic biomarker, with the DQ and DR alleles having significant associations with abnormal wound healing and cutaneous fibrosis. There is strong evidence of a significant immune component in the pathogenesis of each type of fibrotic disorder explored in this review. However, the exact mechanisms remain to be elucidated, since the pathogenesis of cutaneous fibrosis and abnormal wound healing are not fully understood.