A membrane-type surfactant protein D (SP-D) suppresses macrophage-mediated cytotoxicity in swine endothelial cells

作者：Jiaravuthisan Patmika; Maeda Akira; Takakura Chihiro; Wang Han Tang; Sakai Rieko; Shabri Afifah Mohd; Lo Pei Chi; Matsuura Rei; Kodama Tasuku; Eguchi Hiroshi; Okuyama Hiroomi; Miyagawa Shuji^*

来源：Transplant Immunology, 2018, 47: 44-48.

DOI：10.1016/j.trim.2018.02.003

• SP-D
• Xenotransplantation
• Macrophage
• THP-1
• SIRP alpha

Objective: Surfactant protein D (SP-D), which is secreted mainly in the lung, is an oligometric C type lectin that promotes phagocytosis by binding to carbohydrates on microbial surfaces. SP-D can also bind SIRP alpha, leading to a decrease in cytokine production by monocytes/macrophages. In the present study, we examined the possibility that SP-D suppresses macrophage-mediated xenogeneic cytotoxicity, by creating a membrane-type SP-D.& para;& para;Methods: The cDNA for the carbohydrate recognition domain (CRD) of human SP-D was switched to that of a membrane-type protein, collectin placenta 1 (CL-P1), with a Flag-tag. The cDNA of CD47 was prepared as a control. The suppressive function of the membrane-type protein of the hybrid molecule, CL-SP-D, to monocytes/ macrophages was then studied and the results compared with that for CD47.& para;& para;Results: The expression of Flag-tagged CL-SP-D on the transfected SECS and the SIRP alpha on monocyte-like cells, THP-1 cells, was confirmed by FACS using anti-Flag Ab and anti-CD172a, respectively. The molecular size of the hybrid protein was next assessed by western blot. While significant cytotoxicity against SEC was induced in differentiated THP-1 cells, CL-SP-D significantly reduced THP-1-mediated cytotoxicity. In addition, phosphorylated SHP-1 was clearly detected in SEC/CL-SP-D in western blots. Moreover, IL-10 production was upregulated and IL-1 beta production was suppressed in the case of THP-1 and SEC/CL-SP-D, compared with naive SEC.& para;& para;Next, the cytotoxicity caused by the in vitro generated macrophage was assessed under the same conditions as were used for THP-1. CL-SP-D also showed the significant down-regulation on the macrophage. In addition, changes in IL-10 production by the macrophage confirmed the results.& para;& para;Conclusions: These findings indicate that the membrane-type SP-D serve as an effective therapeutic strategy for inhibiting macrophage-mediated xenograft rejection in xenotransplantation.

• 出版日期2018-4