Roles of oolong tea extracts in the protection against Staphylococcus aureus infection in Caenorhabditis elegans

Oolong tea, a popular traditional Chinese tea, possesses various bioactivities, but little is known about its roles in the protection against pathogens, such as Staphylococcus aureus, in vivo. This study investigated the roles of the water-soluble oolong tea extracts (OTE) on S. aureus infection in Caenorhabditis elegans, a promising model to study the host-microbe interactions in vivo. Pretreatment with OTE (0.6% and 1.2%) and co-treatment with OTE and S. aureus extended the lifespan by 11.16%-30.37%, increased the body bends by 36.49%-101.39%, inhibited the lipid accumulation by 11.71%-35.21% and S. aureus colonization in the intestine by 5.02%-30.68%, and enhanced the mitochondrial transmembrane potential by 51.92%-74.83%, compared with the control groups where worms were fed with S. aureus. Moreover, pretreatment with OTE and co-treatment with OTE and S. aureus suppressed the production of reactive oxygen species, increased the production of glutathione and superoxide dismutases (SODs), and altered the transcripts of genes encoding SODs, glutathione-S-transferases, and antimicrobial proteins and peptides in different ways. Furthermore, pretreatment with OTE failed to extend the lifespan of the nematode mutants defective in age-1, akt-2, skn-1, or hsf-1, and co-treatment with OTE and S. aureus could not extend the lifespan of the nematode mutants defective in age-1, akt-2, sek-1, pmk-1, mpk-1, or skn-1. These findings indicated that OTE exhibited the preventive and protective effects on S. aureus infection by increasing the antioxidant properties and expression of antimicrobial proteins and peptides via insulin/IGF-1 and/or p38/ERK mitogen-activated protein kinase (MAPK) pathway and transcription factor SKN-1 and/or HSF-1, which implied OTE could be used as a potential food additive to prevent S. aureus infection. PRACTICAL APPLICATION: Staphylococcus aureus is harmful to animal and human health, such as leading to immune system disorders. This study demonstrated that oolong tea extracts could be a potential additive used in food and feeds to protect animal and human from S. aureus infection by increasing the antioxidant properties and the expression of antimicrobial proteins and peptides.