Human Antimicrobial Peptide Hepcidin 25-Induced Apoptosis in Candida albicans

Abstract

Hepcidin 25 (hep 25) is a cysteine-rich 25-amino acid antimicrobial peptide containing the amino-terminal Cu(II)/Ni(II)-binding (ATCUN) motif. Upon metal binding, the ATCUN motif is known to be involved in the generation of reactive oxygen species (ROS), especially hydrogen peroxide and hydroxyl radicals, which act against different bacterial species. However, the antifungal activity and its correlation to the Cu(II)-ATCUN complex of Hep 25 are still poorly understood. Here, we found that ROS accumulation plays an important role in the fungicidal activity of hep 25 against Candida albicans. In addition, Annexin V-FITC staining and TUNEL assay results provide clues about the apoptosis induced by hep 25. Moreover, hep 25 also increases the generation of ROS, possibly because of copper binding to the ATCUN motif, which is relevant to its activity against C. albicans. Finally, the C. albicans killing action of hep 25 is an energy- and temperature-dependent process that does not involve targeting the membrane. Taken together, our results provide new insights into the mechanisms of hep 25 against C. albicans cells and the potential use of hep 25 and its derivatives as novel antifungal agents.

Copper-binding motifs Xxx-His or Xxx-Zzz-His (ATCUN) linked to an antimicrobial peptide: Cu-binding, antimicrobial activity and ROS production

“…There is the possibility that these AMP acquire Cu(II) in the environment and the Cu-bound form has a modulated activity. This is supported by several reports of an increased peptide's antimicrobial (or antifungal) activity when copper is added [17][18][19]. However, generally modest effects were observed, limited to the same order of magnitude as the AMP without Cu.…”

Antifungal Mechanism of Vip3Aa, a Vegetative Insecticidal Protein, against Pathogenic Fungal Strains

“…The mechanisms of action of numerous AMPs are broadly classified into the following two categories: membranolytic actions such as membrane potential changes and the formation of pores in the cell membrane; and intracellular inhibiting actions such as interfering gene expression, inhibiting enzyme activity, generating reactive oxygen species (ROS), and inducing osmotic pressure [ 28 , 29 ]. There is growing evidence of AMPs inducing cell death by stimulating the production of ROS [ 30 , 31 , 32 , 33 , 34 ]. Although fungal cells repeat the cycle of generating and eliminating intracellular ROS during metabolic pathways, the high levels of ROS damage intracellular lipids, proteins, DNA, organelles, and cell walls [ 35 , 36 ].…”

Antimicrobial Activity of the Peptide LfcinB15 against Candida albicans

“…Redox homeostasis is vital for C. albicans survival. The impacts of AMPs on mitochondrial redox balance to induce ROS accumulation have been reported in several studies [ 38 , 56 , 57 ]. Increased ROS levels lead to oxidative stress, and ROS can induce cell death.…”

“…Indeed, several antifungal agents and AMPs that induce ROS generation can also cause mitochondrial dysfunction. For example, both kalopanaxsaponin A (KPA) and the AMP hepcidin 25 induce ROS generation in C. albicans [ 56 , 59 ]. Additionally, KPA causes a significant decrease in the intracellular ATP level in a dose-dependent manner [ 59 ], and hepcidin 25 is able to reduce the mitochondrial membrane potential [ 56 ].…”

“…For example, both kalopanaxsaponin A (KPA) and the AMP hepcidin 25 induce ROS generation in C. albicans [ 56 , 59 ]. Additionally, KPA causes a significant decrease in the intracellular ATP level in a dose-dependent manner [ 59 ], and hepcidin 25 is able to reduce the mitochondrial membrane potential [ 56 ]. Because LfcinB15 induces ROS generation, several hallmarks of mitochondrial dysfunction were thus examined.…”