Anti-Inflammatory and Skin-Lightening Activities of Exosomes Derived from Latilactobacillus sakei BK-5 Isolated from Aster koraiensis Flowers.

Exosomes are nanosized vesicles released from multivesicular bodies into the extracellular space. Lactic acid bacteria-derived exosomes have emerged as promising next-generation bioactive agents with beneficial effects on skin health and immune regulation. In this study, we aimed to investigate the anti-inflammatory and skin-lightening activities of exosomes derived from Latilactobacillus sakei isolated from the flowers of Aster koraiensis (BK-5 exosomes). Experiments were performed using lipopolysaccharide-stimulated RAW 264.7 macrophages and α-melanocyte-stimulating hormone-induced B16F10 melanoma cells. BK-5 exosomes exhibited no cytotoxicity in either cell line and effectively suppressed the production of proinflammatory cytokines, including interleukin (IL)-6, IL-1β, tumor necrosis factor-α, and prostaglandin E2, as well as the expression of inducible nitric oxide synthase and cyclooxygenase-2. Moreover, BK-5 exosomes reduced the expression of melanogenesis-related proteins, including tyrosinase, tyrosinase-related protein (TRP)-1, TRP-2, and microphthalmia-associated transcription factor in a dose-dependent manner. Furthermore, BK-5 exosomes inhibited the phosphorylation of nuclear factor kappa-light-chain-enhancer of activated B cells and inhibitor of κB alpha, as well as the phosphorylation of mitogen-activated protein kinase pathway components, including extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38. Collectively, these findings confirm that BK-5 exosomes effectively attenuate inflammatory responses in RAW 264.7 macrophages through suppression of multiple signaling pathways and inhibit melanin biosynthesis in B16F10 cells, thereby demonstrating their potential as multifunctional bioactive materials applicable to pharmaceutical and cosmetic fields.