Impact of SCARB2 on pro-inflammatory cytokines in tissues of EV71-infected mice

Background: Scavenger receptor class B, member 2 (SCARB2) participates in early innate immune responses to infection. Our aim in this study was to explore the expression and role of mouse SCARB2 (mSCARB2) in different tissues in EV71-infected mice. Methods: ICR mice were inoculated intraperitoneally (i.p.) with EV71 0.1 ml 10 7.5 TCID 50 /ml. The control mice were injected i.p. with the same volume RD cell lysate. Mice were sacrificed by aether anesthesia at day 4, 8 and 12 post infection (p.i.). Their brain, brainstem, spinal cord, cerebellum, lung and heart were dissected out for determining the number of copies of viral RNA by quantitative real-time PCR (qRT-PCR). Detection of expression of mSCARB2 was performed by immunohistochemistry and qRT-PCR. Cytokines quantification was done by ELISA. Results: The viral loads in central nervous system (CNS) were higher than in lung or/and heart. The expression of mSCARB2 increased in tissues of EV71-infected mice. However, the levels of mSCARB2 increased in CNS were higher than in lung or/and heart within a certain period of time, particularly in brain stem and brain. In addition, local TNF-α, IL-6 and IL-1β levels of production were consistent with mSCARB2 levels of expression in tissues of EV71-infected mice. However, it presented a positive correlation between relative mSCARB2 mRNA level and TNF-α, IL-6 and IL-1β levels in local tissues at day 4 and 8 p.i. Conclusion: Our data revealed that the elevated local mSCARB2 may modulate pro-inflammatory cytokines induction in local tissues, particularly, in CNS of EV71-infected mice.