Mptx2 defends against peritoneal infection by methicillin-resistant staphylococcus aureus.

• Mptx2 has antibacterial activity against MRSA infection. • Mptx2 can suppress the reproduction and biofilm formation of MRSA in vitro. • Mptx2 supplementation promotes macrophages to phagocytize and clear the MRSA. Mptx2 reduces MRSA loading in peritoneal organs of MRSA-infected peritonitis mice. • Mptx2 reduces peritoneal inflammation and damage in MRSA-infected peritonitis mice. Methicillin-resistant Staphylococcus aureus (MRSA) has an increasing prevalence of multi-drug resistance. There is an urgent need for developing novel approaches to combat MRSA infection. Mucosal pentraxin 2 (Mptx2) is predicted to be a member of the pentraxin family, but its biological function is still unknown. This study is aimed to explore the roles of Mptx2 in MRSA-associated peritoneal infection. The recombinant Mptx2 protein is used to evaluate its antibacterial activity. Biofilm formation assay and macrophage phagocytic experiment are performed to explore the involved mechanisms. The effects of Mptx2 on peritoneal infection are investigated in a MRSA-induced peritoneal infected model. We here show that addition of Mptx2 suppresses the growth and biofilm formation of MRSA in vitro. Enzyme-linked immunosorbent assay (ELISA) binding analysis shows that Mptx2 protein directly binds to the MRSA. Additionally, Mptx2 supplementation promotes macrophages to phagocytize and clear the MRSA. In the MRSA-infected peritonitis model , Mptx2 administration reduces MRSA loading in peritoneal organs and alleviates peritoneal damage. Mptx2 knockout aggravates MRSA infection-induced peritoneal injury. In conclusion, our findings reveal that Mptx2 has bactericidal activity against MRSA both in vitro and in vivo, which may shed light on the discovery and development of novel strategies for MRSA-infected peritonitis. [ABSTRACT FROM AUTHOR]