earticle

영어

SIGN-R1, a C-type lectin, is expressed on a subset of resident macrophages in spleen marginal zone. Recently, it was found that SIGN-R1 mediates complement activation pathway by interacting C1q. It is well known that C1q binds to apoptotic cells and has an important role in there clearance. Therefore, we assessed whether SIGN-R1 could be involved in the apoptotic cells clearance, too. In vitro binding assay reveals that soluble SIGN-R1 specifically bind to apoptotic thymocytes. Consistent with our in vitro results, intravenous injected apoptotic cells were uptaken by SIGN-R1-positive macrophages in the splenic marginal zone. To confirm the role of SIGN-R1, apoptotic cells were intravenously injected into control or SIGN-R1 knock-out mice(SR1KO). We observed that apoptotic cells was trapped in the marginal zone at early time point (10min) in both mice which might be due to the presence of other macrophage receptors such as MARCO or Dectin-2. However, as we expected, it was very clear that SIGN-R1 mediated C3 fixation on apoptotic cells in control mice, but not in SR1 KO. Moreover, at 1 hr time point, SR1 KO mice showed the dramatic delay of apoptotic cell clearance in spleen or liver, compared to the control mice. Considered together, our findings suggest that SIGN-R1 specifically mediates complement activation pathway in the splenic marginal zone and this leads to the efficient clearance of apoptotic cells.