[ODP4D] d. Secretion and Transport

[ODP-068] MRSA-derived membrane vesicles act as an IgE-mediated stimulant to induce hypersensitivity

○Krisana Asano^1,2, Shouhei Hirose¹, Kouji Narita^1,3, Akio Nakane^2,4 (¹Dept. Microbiol. Immunol., Hirosaki Univ. Grad. Sch. Med., ²Dept. Biopolym. Health Sci., Hirosaki Univ. Grad. Sch. Med., ³Inst. Anim. Exp., Hirosaki Univ. Grad. Sch. Med., ⁴Hirosaki Univ. Health Welf.)

Membrane vesicles (MVs) released from bacteria carry various functional molecules. They play a role in bacterial communications and delivery of virulence factors. To date, only little is known about methicillin resistant Staphylococcus aureus (MRSA)-derived MVs (SaMV). Regarding the potential of MVs, the protective effect against MRSA infection in SaMV-immunized mice was examined. In contrast to our expectation, all SAMV-immunized mice died within 1 day after MRSA infection, suggesting an anaphylactic induction. Without MRSA infection, the production of proinflammatory cytokines in spleen of SaMV-immunized mice was further examined. It was comparable to that of non-immunized mice. On the other hand, high titer of proinflammatory cytokines was significantly induced after ex vivo stimulating the spleen cells of immunized mice with SaMV. Serum and spleen of SaMV-immunized mice were also collected after infection with MRSA for 3 h. Obviously, spleen of SaMV-immunized mice had larger in size and heavier than non-immunized control. In these mice, the production of IL-6, TNF-α and IL-17 in spleen was higher than control. Simultaneously, IgE production in the serum of immunized mice was enhanced. These results suggested that MRSA-derived MVs play a role in virulence, by acting as a stimulant to induce inflammatory response and IgE-mediated hypersensitivity after MRSA infection.