Staphylococcus pseudintermedius is a common commensal bacterium colonizing the skin and mucosal surfaces of household animals. However, it has recently emerged as a dangerous opportunistic pathogen, comparable to S. aureus for humans. The epidemiological situation is further complicated by the increasing number of methicillin-resistant S. pseudintermedius infections and evidence of gene transmission driving antibiotic resistance between staphylococci colonizing human and zoonotic hosts. In the present study, we describe a unique peptide, BacSp222, that possesses features characteristic of both bacteriocins and virulence factors. BacSp222 is secreted in high quantities by S. pseudintermedius strain 222 isolated from dog skin lesions. This linear, fifty-amino-acid highly cationic peptide is plasmid-encoded and does not exhibit significant sequence similarities to any other known peptides or proteins. BacSp222 kills gram-positive bacteria (at doses ranging from 0.1 to several micromol/l) but also demonstrates significant cytotoxic activities towards eukaryotic cells at slightly higher concentrations. Moreover, at nanomolar concentrations, the peptide also possesses modulatory properties, efficiently enhancing interferon gamma-induced nitric oxide release in murine macrophage-like cell lines. BacSp222 appears to be one of the first examples of multifunctional peptides that breaks the convention of splitting bacteriocins and virulence factors into two unrelated groups.

Proteases play a well-recognized role in the emergence of highly aggregation-prone protein fragments in vivo, while in vitro limited proteolysis is often employed to probe different phases of amyloidogenic pathways. Here we show that addition of moderate amounts of pepsin to acidified bovine insulin at close-to-physiological temperature results in an abrupt self-assembly of amyloid-like fibrils from partially digested insulin fragments. Biochemical analysis of the pepsin-induced fibrils implicates peptide fragments (named H) comprising of the 13 or 15 N-terminal residues of the A-chain and 11 or 13 N-terminal residues of the B-chain linked by disulfide bond between Cys7A-Cys7B as the main constituents. There are up to 8 pepsin-cleavage sites remaining within the double chain peptide which become protected upon fast fibrillation unless concentration of the enzyme is increased resulting in complete digestion of insulin. Controlled re-association of H-peptides leads to explosive fibrillation only under non-reducing conditions implying the key role of the disulfide bond in their amyloidogenicity. Such re-assembled amyloid is similar in terms of morphology and infrared features to typical bovine insulin fibrils although it lacks the ability to seed the intact protein.

Fibrosis of burn-related wounds remains an unresolved clinical issue that leads to patient disability. The aim of this study was to assess the efficacy of the transplantation of adipose-derived stromal cells seeded onto a collagen-based matrix in the reconstruction of burn-related scars. Here, we characterized an in vitro interaction between adipose-derived stromal cells and a collagen-based matrix, Integra^®DRT. Our results show that transcription of pro-angiogenic, remodeling, and immunomodulatory factors was more significant in adipose-derived stromal cells than in fibroblasts. Transcription of metalloproteinases 2 and 9 is positively correlated with the collagenolytic activity of the adipose-derived stromal cells seeded onto Integra^®DRT. The increase in the enzymatic activity corresponds to the decrease in the elasticity of the whole construct. Finally, we validated the treatment of a post-excision wound using adipose-derived stromal cells and an Integra^®DRT construct in a 25-year-old woman suffering from burn-related scars. Scarless healing was observed in the area treated by adipose-derived stromal cells and the Integra^®DRT construct but not in the reference area where Integra^®DRT was applied without cells. This clinical observation may be explained by in vitro findings: Enhanced transcription of the vascular endothelial growth factor as well as remodeling of the collagen-based matrix decreased mechanical stress. Our experimental treatment demonstrated that the adipose-derived stromal cells seeded onto Integra^®DRT exhibit valuable properties that may improve post-excision wound healing and facilitate skin regeneration without scars.