LL-37 amide

PEGylating is an effective way for prolonging the half-time period and decreasing the immunogenicity of protein drugs. With experiments of single factor, it was proved that the optimal processes for PEGylating the fused protein of LL-37 and interferon (IFN)-α2a were: PEG molecular weight was 5,000, fused protein concentration was 0.6 mg/mL, the mole ratio of protein to mPEG₅₀₀₀-SS was 1:10, the reaction temperature was 4 °C, and the pH was 9.0, respectively. With orthogonal experiments, we proved that the influential order of 3 main factors is: the fused protein concentration > the mole ratio of protein and mPEG₅₀₀₀-SS > pH and the optimal conditions were the fused protein concentration as 0.6 mg/mL, the mole ratio of protein and mPEG₅₀₀₀-SS as 1:10, pH as 8.8. Under these optimal conditions, the average rate of PEGylated protein with 3 times parallel experiments was 86.98%. After PEGylated, the interferon activity and antimicrobial activity of fused protein could be remained higher than 58% and 97%, respectively.

Biological functions of human cathelicidin LL-37 have been widely reported, including antibacterial, immune and anti-tumor effects. However, the antiplatelet activity of LL-37 has not been addressed. The purpose of our study was to investigate the antiplatelet and antithrombotic actions of LL-37. We found that this peptide inhibited human platelet aggregation in vitro and attenuated thrombus formation in vivo. Furthermore, LL-37 reduced phosphorylation of Src kinase and Akt(Ser473), decreased platelet spreading on immobilized fibrinogen and inhibited P-selectin expression on platelets. These results demonstrate that LL-37 has antiplatelet and antithrombotic actions.

Antimicrobial peptides (AMPs) are effector molecules of the innate immune system of the skin. They present an activity against a broad spectrum of Gram-positive and Gram-negative bacteria as well as some fungi, parasites and enveloped viruses. Several inflammatory skin diseases including psoriasis, atopic dermatitis, acne vulgaris and rosacea are characterized by a dysregulated expression of AMPs. Antimicrobial peptides are excessively produced in lesional psoriatic scales or rosacea in contrast to the atopic skin that shows lower AMP levels when compared with psoriasis. The importance of the AMPs contribution to host immunity is indisputable as alterations in the antimicrobial peptide expression have been associated with various pathologic processes. This review discusses the biology and clinical relevance of antimicrobial peptides expressed in the skin and their role in the pathogenesis of inflammatory skin diseases.

When skin is damaged it must simultaneously identify the nature of the injury, repair barrier function, and limit the intrusion of pathogenic organisms. These needs are carried out through the detection of damage associated molecular patterns (DAMPs), and a response that includes secretion of cytokines, chemokines, growth factors and antimicrobial peptides (AMPs). In this study, we analyzed how non-coding double stranded RNA (dsRNAs) acts as a DAMP in the skin and how the human cathelicidin AMP LL-37 might influence growth factor production in response to this DAMP. dsRNA alone significantly increased the expression of multiple growth factors in keratinocytes, endothelial cells, and fibroblasts. Furthermore, RNA-seq transcriptome analysis found that multiple growth factors increase when cells are exposed to both LL-37 and dsRNA, a condition that mimics normal wounding. qPCR and/or ELISA validated that growth factors expressed by keratinocytes in these conditions included, but were not limited to, basic fibroblast growth factor (FGF2), Heparin-binding EGF-like growth factor (HBEGF), vascular endothelial growth factor C (VEGFC), Betacellulin (BTC), epidermal growth factor (EGF), epiregulin (EREG), insulin growth factor-like family member 1 (IGFL1), and other members of the transforming growth factor beta superfamily.