A soluble form of Siglec-9 provides a resistance against Group B Streptococcus (GBS) infection in transgenic mice

作者：Saito Mitsumasa; Yamamoto Sayo; Ozaki Kinuyo; Tomioka Yukiko; Suyama Haruka; Morimatsu Masami; Nishijima Ken ichi; Yoshida Shin ichi; Ono Etsuro^*

来源：Microbial Pathogenesis, 2016, 99: 106-110.

DOI：10.1016/j.micpath.2016.08.014

• Soluble Siglec-9
• Group B Streptococcus
• Antibacterial benefit
• Transgenic mice

Group B Streptococcus (GBS) is a leading cause of invasive bacterial infections in human newborns. A key GBS virulence factor is its capsular polysaccharide (CPS), possessing terminal sialic acid residues that suppress host immune response and provide a survival advantage to the pathogen. CPS binds to Siglec-9 expressed on neutrophils, which is expected to down-regulate the immune responsiveness of neutrophils. We hypothesized that a soluble form of Siglec-9 (sSiglec-9) competitively inhibits a binding of CPS to Siglec-9 on immune cells, leading to provide antibacterial benefit against GBS infection in the transgenic mouse line expressing sSiglec-9 (sSiglec-9 Tg). The sSiglec-9 in the sera of sSiglec-9 Tg bound to the sialylated-GBS strains belonging to serotypes Ia, Ib, II, III, IV and V in whole GBS cell ELISA. When GBS cells of serotype III that is a common serotype in late-onset GBS disease (LOD) were intraperitoneally inoculated into sSiglec-9 Tg, sSiglec-9 Tg showed a significant resistance as compared with non-transgenic littermates. Furthermore, GBS serotype III organisms were not detected in cultures of the blood from surviving mice (<1 x 10(3) CFU/ml). These results indicated that sSiglec-9 Tg mice were more efficient in eliminating GBS and survived better after the intraperitoneal challenge with GBS serotype III bacteria.

• 出版日期2016-10