Encapsulation of a novel peptide derived from histatin-1 in liposomes against initial enamel caries in vitro and in vivo

OBJECTIVES

Biomimetic mineralization mediated by proteins and peptides is a promising strategy for enamel repair, and its specific application model needs more research. In this work, we exploited a liposomal delivery system for a novel peptide (DK5) derived from histatin-1 (DK5-Lips) as a new biomimetic mineralization strategy against initial enamel caries.

MATERIALS AND METHODS

The DK5-Lips was prepared using calcium acetate gradient method and then the in vitro release, salivary stability, and cytotoxicity were studied. Initial enamel caries was created in bovine enamel blocks and subjected to pH-cycling model treated with DK5-Lips. Surface microhardness testing, polarized light microscopy (PLM), and transverse microradiography (TMR) were analyzed. Then the biocompatibility of DK5-Lips was evaluated in the caries model of Sprague-Dawley rats, and the anti-caries effect was assessed using Micro-CT analysis, Keyes scores, and PLM in vivo.

RESULTS

DK5-Lips provided a mean particle size of (97.63 ± 4.94)nm and encapsulation efficiency of (61.46 ± 1.44)%, exhibiting a sustained release profile, excellent stability in saliva, and no significant toxicity on human gingival fibroblasts (HGFs). The DK5-Lips group had higher surface microhardness recovery, shallower caries depth, and less mineral loss in bovine enamel. Animal experiments showed higher volume and density values of residual molar enamel, lower Keyes score, and shallower lesion depth of the DK5-Lips group with good biocompatibility.

CONCLUSION

As a safe and effective application model, DK5-Lips could significantly promote the remineralization of initial enamel caries both in vitro and in vivo.

CLINICAL RELEVANCE

The potential of liposome utilization as vehicle for oral delivery of functional peptides may provide a new way for enamel restoration.

Combating fungal phytopathogens with human salivary antimicrobial peptide histatin 5 through a multi-target mechanism

Blast disease caused by Magnaporthe oryzae is a major contributor to decreased crop yield and rice production globally. The use of chemical fungicides to combat crop pathogens is not only unsafe but also promotes the emergence of pathogenic variants, leading to recurrent host infections. To address plant diseases, antimicrobial peptides have emerged as a promising alternative as they are effective, safe, and biodegradable antifungal agents. This study examines the antifungal activity and mechanism of action of the human salivary peptide histatin 5 (Hst5) on M. oryzae. Hst5 causes morphogenetic defects in the fungus, including non-uniform chitin distribution on the fungal cell wall and septa, deformed hyphal branching, and cell lysis. Importantly, a pore-forming mechanism of Hst5 in M. oryzae was ruled out. Furthermore, the interaction of Hst5 with the M. oryzae genomic DNA suggests that the peptide may also influence gene expression in the blast fungus. In addition to its effects on morphogenetic defects and cell lysis, Hst5 also inhibits conidial germination, appressorium formation, and the appearance of blast lesions on rice leaves. The elucidated multi-target antifungal mechanism of Hst5 in M. oryzae provides an environmentally friendly alternative to combating blast infections in rice by preventing fungal pathogenicity. The promising antifungal characteristics of the AMP peptide may also be explored for other crop pathogens, making it a potential biofungicide for the future.