Silibinin is a promising candidate for the development of anti-virulence therapeutic agents to treat Streptococcus suis serotype 2 infections. - GreenMedInfo Summary

AIMS: To determine the antivirulence properties of silibinin against suilysin (SLY), a virulence factor of Streptococcus suis serotype 2 (SS2) that plays an important role in the pathogenesis of S. suis infection and its protective effect against SS2 infection in a mouse model.

METHODS AND RESULTS: Susceptibility testing, haemolysis assay and Western blot assays were employed to evaluate the performance of silibinin on SLY pore-forming activity. Cytotoxicity assays and mouse infection tests were also performed to determine the efficacy of silibinin against SS2 infection. The results showed that silibinin, a flavonoid with little anti-S. suis activity, was identified to be a potent antagonist of SLY-mediated haemolysis through the inhibition of its oligomerization. Treatment with silibinin reduced S. suis-induced cytotoxicity in macrophages (J774 cells). In addition, S. suis-infected mice that received silibinin showed a lower bacterial burden.

CONCLUSIONS: Our results demonstrated that silibinin is a promising candidate for the development of antivirulence therapeutic agents to treat S. suis infections.

SIGNIFICANCE AND IMPACT OF THE STUDY: The antivirulent property of silibinin against SS2 by targeting SLY provides the possibility for the future pharmaceutical application of silibinin to prevent and treat S. suis infection.