Abstract:

Bovine milk exosomes were purified by density centrifugation, and their effect on skin barrier was studied. TEM, nanoFCM, Western-blot, LC-MS and BCA test showed that, the obtained bovine milk exosomes were highly pure exosome product whose appearance, particle size and markers were consistent with the typical characteristics of exosomes. Proteomics was then employed. The results showed that, the bovine milk exosomes contributed to cell-cell adhesion, indicative of an effect of skin barrier repair. HaCat cells were then incubated with bovine milk exosomes, and the cell proteomics analysis proved that tight junction proteins such as Claudin-1 and Claudin-6 were upregulated by bovine milk exosomes at all dosages, while some negative regulatory factors like PPP2R1A and PPP2R2A were downregulated. Molecular analysis identified with the proteomics results showed that Claudin-1 was upregulated at both transcription and translation levels. The bovine milk exosomes were then labeled with fluorescent dye and topically applied on mouse skin. Trans-epidermal trace of labeled bovine milk exosomes was demonstrated by fluorescence confocal microscopy. Immunohistochemical detection further verified that Claudin-1 was enhanced after 48 hours’ topical application on mouse skin.

Key words: bovine milk exosome, tight junction, skin barrier