Antimicrobial peptide LL-37 attenuates LTA induced inflammatory effect in macrophages

LL-37/hCAP-18, as the only human cathelicidin, plays an important role in inflammation. Lipoteichoic acid (LTA) is an important bacterial component of Staphylococcus aureus, which is one of the common human pathogens for severe respiratory infection with increasing morbidity in recent years. The present study is to investigate the role of LL-37 in LTA induced inflammatory reaction in macrophages. We examined TNF-α and IL-6 production after LL-37 treatment and discussed its signal transduction pathways such as p38MAPK and Akt activation in macrophages. The expression of pro-inflammatory cytokines was analyzed by quantitative real-time RT-PCR and enzyme-linked immunosorbent assay (ELISA). The LL-37 expression was determined by Western blot and immunofluorescence staining. The results showed that LL-37 was upregulated after LTA treatment. It could inhibit LTA induced p38MAPK and Akt phosphorylation and attenuate TNF-α and IL-6 production in macrophages in some specific concentration. These results suggest that LL-37 exerts an anti-inflammatory property and attenuates the pro-inflammatory cytokine release in macrophages.

► Staphylococcus aureus LTA could induce severe inflammation reaction in macrophages. ► Autocrined peptide, LL-37, significantly inhibits S. aureus LTA induced inflammation. ► LL-37 attenuates LTA induced production of TNF-α and IL-6 in macrophages to regulate the homeostasis of immune reaction. ► LL-37 attenuates the inflammation by inhibiting the phosphorylation of p38MAPK and Akt in macrophages.