Exon skipping of TGFßRI affects signalling and ECM expression in hypertrophic scar-derived fibroblasts.

BACKGROUND: In burn patients, wound healing is often accompanied by hypertrophic scar (HS) development, resulting in both functional and aesthetic problems. HSs are characterised by abundant presence of myofibroblasts that contribute to overproduction of extracellular matrix (ECM) that is regulated by the TGF-ß signalling pathway. Studies have shown that inhibition of TGF-ß receptors in fibrotic diseases reduces the fibrotic load. In the present study, we aim to inactivate ALK5, also known as TGF-ß receptor I, in human HS fibroblasts by exon skipping using antisense oligonucleotides (AONs). METHODS: HS biopsies were used to isolate and set up fibroblast monocultures. AONs targeting ALK5 were supplemented to the fibroblast cultures to induce exon skipping, while pharmacological ALK5 inhibition was induced using SB431542. AON delivery in HS fibroblasts was examined using immunofluorescence (IF), while TGF-ß signalling downstream targets, such as Smad2/3, PAI-1, ACTA2, COL1A1 and COL3A1, were analysed using touchdown polymerase chain reaction (PCR), quantitative PCR (qPCR), IF or western blotting. RESULTS: Our data clearly demonstrate that AONs were successfully delivered in the nuclei of HS fibroblasts and that functional exon skipping of ALK5 took place as confirmed with touchdown PCR and qPCR. In addition, exon skipping affected the expression of ECM-related genes, such as type I/III collagens, PAI-1 and CCN2. Moreover, AON treatment did not affect the migration of HS fibroblasts in a model for wound healing. CONCLUSION: Exon skipping is a promising tool to modulate the TGF-ß signalling pathway in HS. This would open a therapeutic window for the treatment of patients suffering from HSs.

Eradication of meticillin-resistant Staphylococcus aureus from human skin by the novel LL-37-derived peptide P10 in four pharmaceutical ointments.

Skin bacterial colonization/infection is a frequent cause of morbidity in patients with chronic wounds and allergic/inflammatory skin diseases. This study aimed to develop a novel approach to eradicate meticillin-resistant Staphylococcus aureus (MRSA) from human skin. To achieve this, the stability and antibacterial activity of the novel LL-37-derived peptide P10 in four ointments was compared. Results indicate that P10 is chemically stable and antibacterial in hypromellose gel and Softisan-containing cream, but not in Cetomacrogol cream (with or without Vaseline), at 4 °C for 16 months. Reduction in MRSA counts on Leiden human epidermal models (LEMs) by P10 in hypromellose gel was greater than that of the peptide in Cetomacrogol cream or phosphate buffered saline. P10 did not show adverse effects on LEMs irrespective of the ointment used, while Cetomacrogol with Vaseline and Softisan cream, but not hypromellose gel or Cetomacrogol cream, destroyed MRSA-colonized LEMs. Taking all this into account, P10 in hypromellose gel dose-dependently reduced MRSA colonizing the stratum corneum of the epidermis as well as biofilms of this bacterial strain on LEMs. Moreover, P10 dose-dependently reduced MRSA counts on ex-vivo human skin, with P10 in hypromellose gel being more effective than P10 in Cetomacrogol and Softisan creams. P10 in hypromellose gel is a strong candidate for eradication of MRSA from human skin.