title: Expression and role of IL-15 in post-burn hypertrophic scars.
abstract: Hypertrophic scarring is a skin disorder that occurs after wounding and thermal injury. There is accumulating evidence that immunologic processes such as infiltration of activated T lymphocytes and altered cytokine production may play a role in the formation of hypertrophic scars. Interleukin-15, a cytokine identified as a T cell growth factor, also acts as a chemoattractant for T cells and has pro-inflammatory properties. We investigated the expression and the role of this cytokine in hypertrophic scarring. IL-15 expression was compared in skin biopsies of hypertrophic scars (HS) both in active (AHS) and in remission (RHS) phases, in normotrophic scars (NTS) and in normal skin using reverse transcriptase-polymerase chain reaction and immunohistochemistry. IL-15 expression in HS was significantly higher than in NTS or normal skin. Furthermore, AHS expressed higher levels of IL-15 than RHS. Immunohistologic analysis of AHS samples showed strong IL-15 immunoreactivity in keratinocytes and Langerhans cells in the epidermis and in macrophages, fibroblasts, and dermal dendritic cells in the dermis. High levels of IL-15 expression in AHS correlated with abundant infiltration of activated CD3+ cells. Ex vivo experiments indicate that IL-15 can sustain the proliferative response of T cells derived from AHS but not from RHS and NTS. In addition, IL-15 prevents both cytokine deprivation and activation-induced apoptosis of T cells derived from AHS. Taken together, these results suggest that IL-15 can be involved in the recruitment, proliferation, and apoptosis inhibition of T cells in AHS. The findings that the evolution from an AHS to a RHS is associated with a decrease in IL15 expression, and with a loss of IL-15 responsiveness in ex vivo-cultured T cells, indicate that this cytokine plays an important role in the biology of pathologic scar formation.
authors.affiliation: Department of Plastic Surgery, Traumatological Centre, Turin, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Castagnoli
authors.forename: C
authors.initials: C
authors.lastname: Trombotto
authors.forename: S
authors.initials: S
authors.lastname: Ariotti
authors.forename: M
authors.initials: M
authors.lastname: Millesimo
authors.forename: D
authors.initials: D
authors.lastname: Ravarino
authors.forename: G
authors.initials: G
authors.lastname: Magliacani
authors.forename: A N
authors.initials: AN
authors.lastname: Ponzi
authors.forename: M
authors.initials: M
authors.lastname: Stella
authors.forename: S
authors.initials: S
authors.lastname: Teich-Alasia
authors.forename: F
authors.initials: F
authors.lastname: Novelli
authors.forename: T
authors.initials: T
authors.lastname: Musso
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000187:drug effects; D017252:CD3 Complex; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D017439:Cicatrix, Hypertrophic / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D019409:Interleukin-15 / Q000235:genetics* / Q000494:pharmacology / Q000502:physiology*; D007376:Interleukin-2 / Q000494:pharmacology; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000187:drug effects; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology
chemical_list: D017252:CD3 Complex; D019409:Interleukin-15; D007376:Interleukin-2; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger