Intracellular replication inhibitory effects of Galla Rhois ethanol extract for Brucella abortus infection

Ethnopharmacological relevance: Galla Rhois (GR) has long been applied in traditional Korean and Oriental medicine. Although GR has an anti-bacterial effect, the anti-bacterial mechanism and therapeutic efficiency of GR for intracellular parasitic Brucella infection are still unclear. Aim of the study: The objective of this study was to investigate the antibacterial and therapeutic effects of GR ethanol extract (GRE), which is a natural antibacterial component for the treatment of Brucella abortus infection. Materials and methods: The antibacterial activity of GRE towards Brucella abortus was evaluated by incubating Brucella abortus with GRE. Following treatment with GRE, Brucella abortus adherence, uptake, intracellular growth, and intracellular trafficking in macrophages were monitored. Mice were infected intraperitoneally with Brucella abortus and treated orally with GRE for 14 days, and then the weight and CFUs from each spleen were monitored. Results: The viability of Brucella abortus was markedly decreased in a dose-dependent manner. Moreover, Brucella abortus internalization and intracellular growth within macrophages were reduced in GRE-treated cells. The number of bacteria that adhered to GRE-pretreated cells was significantly lower than that of untreated cells. With regards to intracellular trafficking, treatment with GRE augmented the colocalization of Brucella abortus-containing phagosomes with LAMP-1. GRE-treated mice showed considerably decreased weight and bacterial burdens in the spleen compared to untreated mice. Conclusion: GRE exhibits antibacterial and protective effects on Brucella abortus in vitro and in vivo. These results highlight the beneficial effects of GRE in the prevention and treatment of brucellosis.