Thrombin-Derived C-Terminal Peptide Reduces Candida -Induced Inflammation and Infection In Vitro and In Vivo

Abstract

Infections due to the opportunistic fungus Candida have been on the rise in the last decades, especially in immunocompromised individuals and hospital settings. Unfortunately, the treatments available today are limited. Thrombin-derived C-terminal peptide (TCP-25) is an antimicrobial peptide (AMP) with antibacterial and immunomodulatory effects. In this work, we, for the first time, demonstrate TCP-25’s ability to counteract Candida in vitro and in vivo . Using a combination of viable count assay, radial diffusion assay, fluorescence and transmission electron microscopy analyses, TCP-25 was found to exert a direct fungicidal activity. An inhibitory activity of TCP-25 on NF-κB activation induced by both zymosan alone and heat-killed C. albicans was demonstrated in vitro using THP-1 cells, and in vivo using NF-κB reporter mice. Moreover, the immunomodulatory property of TCP-25 was further substantiated in vitro by analyzing cytokine responses in human blood stimulated with zymosan, and in vivo employing a zymosan-induced peritonitis model in C57BL/6 mice. The therapeutic potential of TCP-25 was demonstrated in mice infected with luminescent C. albicans . Finally, the binding between TCP-25 and zymosan was investigated using circular dichroism spectroscopy and intrinsic fluorescence analysis. Taken together, our results show that TCP-25 has a dual function by inhibiting Candida as well as the associated zymosan-induced inflammation. The latter function is accompanied by a change in secondary structure upon binding to zymosan. TCP-25, therefore, shows promise as a novel drug candidate against Candida infections.

A heptadeca amino acid peptide subunit of cathelicidin LL‐37 has previously unreported antifungal activity

“…The spectra were recorded at a wavelength range of 190-280 nm with a scanning speed of 100 nm/ min. The signal, mdeg unit, was converted to molar ellipticity and the ⍺-helix content was calculated as described elsewhere [31].…”

Chemical Barrier Proteins in Human Body Fluids

“…The analysis of wound fluids from the normal healing process and infected wounds revealed differences in the secreted proteins and processed peptides between the studied groups [ 85 , 86 ] that can lead to deteriorated healing. Since the proteolytic events are also crucial for the processing of AMPs [ 9 , 87 ], nosocomial wound infections may alter the host defense system by altering the production of AMPs in the wound fluid.…”