C-Terminal Amination of a Cationic Anti-Inflammatory Peptide Improves Bioavailability and Inhibitory Activity Against LPS-Induced Inflammation

Abstract

Lipopolysaccharide (LPS) has been implicated as a major cause of inflammation and an uncontrolled LPS response increases the risk of localized inflammation and sepsis. While some native peptides are helpful in the treatment of LPS-induced inflammation, the use of these peptides is limited due to their potential cytotoxicity and poor anti-inflammatory activity. Hybridization is an effective approach for overcoming this problem. In this study, a novel hybrid anti-inflammatory peptide that combines the active center of Cathelicidin 2 (CATH2) with thymopentin (TP5) was designed [CTP, CATH2 (1–13)-TP5]. CTP was found to have higher anti-inflammatory effects than its parental peptides through directly LPS neutralization. However, CTP scarcely inhibited the attachment of LPS to cell membranes or suppressed an established LPS-induced inflammation due to poor cellular uptake. The C-terminal amine modification of CTP (CTP-NH2) was then designed based on the hypothesis that C-terminal amidation can enhance the cell uptake by increasing the hydrophobicity of the peptide. Compared with CTP, CTP-NH2 showed enhanced anti-inflammatory activity and lower cytotoxicity. CTP-NH2 not only has strong LPS neutralizing activity, but also can significantly inhibit the LPS attachment and the intracellular inflammatory response. The intracellular anti-inflammatory effect of CTP-NH2 was associated with blocking of LPS binding to the Toll-like receptor 4-myeloid differentiation factor 2 complex and inhibiting the nuclear factor-kappa B pathway. In addition, the anti-inflammatory effect of CTP-NH2 was confirmed using a murine LPS-induced sepsis model. Collectively, these findings suggest that CTP-NH2 could be developed into a novel anti-inflammatory drug. This successful modification provides a design strategy to improve the cellular uptake and anti-inflammatory activity of peptide agents.

Novel Hybrid Peptide Cathelicidin 2 (1-13)-Thymopentin (TP5) and Its Derived Peptides with Effective Antibacterial, Antibiofilm, and Anti-Adhesion Activities

“…The antimicrobial activity of AMPs depends mainly on their physicochemical properties, including net charge number, hydrophobicity, and amphiphilicity [39]. Among the three peptides, CTP-NH 2 showed the strongest antimicrobial activity, reflected by the lowest MICs and MBCs on most of the tested strains, which was consistent with Zhang's report [28] that the hydrophobicity of CTP-NH 2 was stronger than that of the original peptide caused by the C-terminal amidation, increasing its antimicrobial activity [40,41]. Moreover, the MICs of CTP and CTPQ were identical for most of the tested strains, suggesting that they had almost the same antibacterial activity.…”

“…In our previous study, we designed and screened the α-helical cationic peptide, CTP, which could exert anti-inflammatory activity by neutralizing lipopolysaccharide (LPS) and competitively inhibiting the binding of LPS to TLR4/MD2 complex receptors on the cell membrane surface [28]. In addition, modification of the CTP peptide by C-terminal amidation (CTP-NH 2 ) was able to enhance its anti-inflammatory activity and reduce its cytotoxicity to RAW 264.7 cells [28]. However, amidation of the C-terminus is difficult to achieve directly in a heterologous expression.…”

“…We previously designed and screened a hybrid peptide CTP (RWGRFLRKIRRFR-RKDVT), which is composed of the active center of cathelicidin 2 (CATH2) and thymopentin (TP5) (CTP, CATH2 (1-13)-TP5) and exhibits anti-inflammatory and immune activities [28]. We found that the C-terminal amidated CTP (CTP-NH 2 ) had lower cytotoxicity in mouse macrophage (RAW264.7) cells and better anti-inflammatory effects in lipopolysaccharide (LPS)-induced inflammation in vitro and In vivo [28]. However, the amidation reaction of the C-terminal of CTP-NH 2 is difficult to achieve directly in a heterologous expression.…”

Apigetrin Abrogates Lipopolysaccharide-Induced Inflammation in L6 Skeletal Muscle Cells through NF-κB/MAPK Signaling Pathways

“…Inflammation is involved in the pathogenesis of lipopolysaccharide (LPS)-induced damage [ 7 ]. LPS has been implicated as a major cause of inflammation and an important component of the cell wall of Gram-negative bacteria [ 8 ]. Additionally, it stimulates the production and secretion of cytokines and other inflammatory mediators in skeletal muscle cells, resulting in a proinflammatory response [ 9 , 10 ].…”

Antimicrobial and Anti-Inflammatory Activities of MAF-1-Derived Antimicrobial Peptide Mt6 and Its D-Enantiomer D-Mt6 against Acinetobacter baumannii by Targeting Cell Membranes and Lipopolysaccharide Interaction

“…It has been estimated that if effective strategies do not counteract these hospital-acquired infections, around 10 million deaths annually will be caused by the infections by 2050 ( 3 ). Hence, there is a pressing need to find and develop novel medications with better pharmacological profiles and fewer side effects ( 4 – 6 ). Acinetobacter baumannii is one of the multidrug-resistant pathogens that causes hospital-acquired infections.…”