Streptomyces coelicolor secretoma protects astrocytes from oxidative stress

Streptomycetes are gram-positive bacteria that produce about 2/3 of pharmaceutically active secondary metabolites, such as antibiotics, and anti-tumor, immunosuppressive, antifungal and antiparasitic agents. In this study, we investigated the possible effects of Streptomyces coelicolor extracts and putative vesicular fraction on primary cultures of rat astrocytes, in both physiological and stressed conditions, induced by treatment with hydrogen peroxide. Briefly, crude extracts and putative vesicular fractions were prepared from two S.coelicolor strains (M145 wild-type strain and bold F166 strain), and used to treat primary astrocytes, which were then also treated with hydrogen peroxide. Data obtained show that both the general protein pattern of S.coelicolor and putative vesicular fraction vary at different times of growth. M145 strain vesicles and the crude extracts from both strains have a protective effect on stressed astrocytes. The protective effects are higher with the vesicular fraction from bacteria at 18 and 72h of growth. The 166 strain crude extract has a greater protective effect than M145 strain, especially in the initial stages of growth: 18h and 24h. Although they need further studies, these observations are very promising and suggest that, in the future, molecules produced by these bacteria may offer a protection against the high ROS production observed in many pathological conditions, such as in neurodegenerative diseases.