ABSTRACT
BACKGROUND: Capsular contracture is the most common complication following breast implant placement. Cathelicidin LL-37 is a cationic peptide involved in innate immunity. Initially investigated for its antimicrobial role, it was found to have pleiotropic activities, such as immunomodulation, angiogenesis stimulation and tissue healing. The aim of the study was to investigate the expression and localization of LL-37 in human breast implant capsules and its relationship with capsular formation, remodeling and clinical outcomes. METHODS: The study enrolled 28 women (29 implants) who underwent expander substitution with definitive implant. Contracture severity was evaluated. Specimens were stained with hematoxylin/eosin, Masson trichrome, immunohistochemistry and immunofluorescence for LL-37, CD68, α-SMA, Collagen type I and III, CD31 and TLR-4. RESULTS: LL-37 was expressed in macrophages and myofibroblasts of capsular tissue in 10 (34%) and 9 (31%) of the specimens, respectively. In 8 cases (27.5%) it was expressed by both macrophages and myofibroblasts of the same specimen. In infected capsules, expression by both cell types was found in all (100%) specimens. LL-37 expression by myofibroblasts positively correlated with its expression by macrophages (p<0.001). Moreover, LL-37 expression by macrophages of peri-expander capsules negatively correlated with the severity of capsular contracture on definitive implants (p=0.04). CONCLUSIONS: This study demonstrates the expression of LL-37 in macrophages and myofibroblasts of capsular tissue and its negative correlation with the severity of capsular contracture following permanent implant placement. Expression or up-regulation of LL-37 may be involved in myofibroblast and macrophages modulation, thus playing a role in the pathogenic fibrotic process underlying capsular contracture.
