The Combination of Synoeca-MP Antimicrobial Peptide with IDR-1018 Stimulates Proliferation, Migration, and the Expression of Pro-Regenerative Genes in Both Human Skin Cell Cultures and 3D Skin Equivalents.

In skin lesions, the development of microbial infection affects the healing process, increasing morbidity and mortality rates in patients with severe burns, diabetic foot, and other types of skin injuries. Synoeca-MP is an antimicrobial peptide (AMP) that exhibits activity against several bacteria of clinical importance, but its cytotoxicity can represent a problem for its positioning as an effective antimicrobial compound. In contrast, the immunomodulatory peptide IDR-1018 presents low toxicity and a wide regenerative potential due to its ability to reduce apoptotic mRNA expression and promote skin cell proliferation. In the present study, we used human skin cells and a 3D skin equivalent models to analyze the potential of the IDR-1018 peptide to attenuate the cytotoxicity of synoeca-MP, as well as the influence of synoeca-MP/IDR-1018 combination on cell proliferation, regenerative processes, and wound repair. We found that the addition of IDR-1018 significantly improved the biological properties of synoeca-MP on skin cells without modifying its antibacterial activity against S. aureus. Likewise, in both melanocytes and keratinocytes, the treatment with synoeca-MP/IDR-1018 combination induces cell proliferation and migration, while in a 3D human skin equivalent model, it can accelerate wound reepithelization. Furthermore, treatment with this peptide combination generates an up-regulation in the expression of pro-regenerative genes in both monolayer cell cultures and in 3D skin equivalents. This data suggests that the synoeca-MP/IDR-1018 combination possesses a good profile of antimicrobial and pro-regenerative activity, opening the door to the development of new strategies for the treatment of skin lesions.

Senotherapeutic peptide treatment reduces biological age and senescence burden in human skin models.

Cellular senescence is known to play a role in age-related skin function deterioration which potentially influences longevity. Here, a two-step phenotypic screening was performed to identify senotherapeutic peptides, leading to the identification of Peptide (Pep) 14. Pep 14 effectively decreased human dermal fibroblast senescence burden induced by Hutchinson-Gilford Progeria Syndrome (HGPS), chronological aging, ultraviolet-B radiation (UVB), and etoposide treatment, without inducing significant toxicity. Pep 14 functions via modulation of PP2A, an understudied holoenzyme that promotes genomic stability and is involved in DNA repair and senescence pathways. At the single-cell level, Pep 14 modulates genes that prevent senescence progression by arresting the cell cycle and enhancing DNA repair, which consequently reduce the number of cells progressing to late senescence. When applied on aged ex vivo skin, Pep 14 promoted a healthy skin phenotype with structural and molecular resemblance to young ex vivo skin, decreased the expression of senescence markers, including SASP, and reduced the DNA methylation age. In summary, this work shows the safe reduction of the biological age of ex vivo human skins by a senomorphic peptide.

In vitro and in vivo toxicity assessment of the senotherapeutic Peptide 14.

Senotherapeutic molecules decrease cellular senescence burden, constituting promising approaches to combat the accumulation of senescent cells observed in chronological aging and age-related diseases. Numerous molecules have displayed senotherapeutic potential, but toxicity has been frequently observed. Recently, a new senotherapeutic compound, Peptide 14, was developed to modulate cellular senescence in the skin. In order to assess the potential toxic and genotoxic effects of the peptide, we observed the viability of human primary dermal fibroblasts and epidermal keratinocytes with Peptide 14 treatment, and show that it is mostly non-toxic in concentrations up to 100 µM. Cancer lines were also used to investigate its potential of modulating proliferation. Different concentrations of the peptide promoted a discrete reduction in the proliferation of cancerous cells of the MeWo and HeLa lineages. In full-thickness human skin equivalents, topically formulated Peptide 14 also failed to exert any significant irritation, nor cellular toxicity when added to the culture media. Genotoxic assays including the Ames, micronucleus, and karyotyping tests also indicate the safety of the peptide. Finally, the irritative potential of the peptide was assessed in human subjects in a repeated insult patch test executed using 1 mM peptide. No visible skin reactions were observed in any of the 54 participants. Taken together, the present data support that Peptide 14 is a senotherapeutic molecule with a positive safety profile as tested with cruelty-free models, justifying further studies involving the peptide.