Objective : To investigate the effect and mechanism of M2 macrophage polarization induced by HCT116 with highly metastatic colorectal cancer cells on immune escape in colorectal cancer. Methods : After the co-culture of colorectal cancer cells conditioned medium(CM) and PMA-induced M0 macrophages, the polarization of M2 macrophages was observed by flow cytometry, real-time polymerase chain reaction(qPCR) and enzyme-linked immunosorbent assay(ELISA) experiments. The CMM0, CMSW480-Mφ and CMHCT116-Mφ were co-cultured with HCT116 cells, and the expression of programmed death-ligand 1(PD-L1) was detected by Western blot and qPCR. At the same time, the stimulated HCT116 cells were co-cultured with human T lymphocytes to detect the survival of HCT116 cells and the levels of tumor necrosis factor-α(TNF-α) and interferon-γ(IFN-γ). The difference of kruüppel-like factor 4(KLF4) expression between SW480 and HCT116 cells was detected by Western blots, qPCR and ELISA. After pretreatment of HCT116 cells with KFL4 inhibitor Kenpaullone(Ken), the CMHCT116 and CMHCT116+Ken were co-cultured with M0 macrophages and the polarization of M2 macrophages was observed by flow cytometry, qPCR and ELISA. The CMHCT116-Mφ and CM_((HCT116+Ken)-Mφ) was co-cultured with HCT116 cells, and the PD-L1 expression of HCT116 cells was detected by Western blot and qPCR. Results: After the stimulation of M0 macrophages with CM, the proportion of CD11b+CD206+ cells in HCT116-Mφ cells was higher, and the expression of M2 macrophage markers interleukin(IL-10) and transforming growth factor-β(TGF-β) were higher. Compared with the CMSW480-Mφ group, the PD-L1 protein expression level was higher in the CMHCT116-Mφ group. After co-culture with T lymphocytes, the cell survival rate are the most in CMHCT116-Mφ group, while the levels of TNF-α and IFN-γ were the lowest. After the addition of Ken, the polarization ratio and markers of M2 macrophages decreased. Compared with CMHCT116-Mφ group, the expression of PD-L1 in HCT116 cells of the CM_((HCT116+Ken)-Mφ) group decreased. Conclusion Highly metastatic colorectal cancer cells induce polarization of M2 macrophages by secreting KLF4, promote PD-L1 expression in colorectal cancer cells, facilitate tumor immune escape, and provide potential targets for clinical immunotherapy.

Objective To discuss causation and clinical treatment of complication in anterior decompression and fixation technique (ADFT) for thoracolumbar fractures with associated paraplegia. Methods A total of 204 cases that had thoracolumbar fractures with paraplegia were operated with ADFT from 1998 to 2004. Of all, 51 times (34 cases) of complication took place. Change of Cob angle was measured according to X-film of thoracolumbar spine before and after operation. Meanwhile, sensation and motion of patients was evaluated. Results There was incision infection leading to septic cerebo-meningtis in one case, CSF leakage in seven, pneumothorax in eight, rib nerve-root injure in five, lumbar nerve-root injure in two, genitofemoral nerve injure in three, lateral femoral cutaneous nerve injure in two, kyphosis in three, deep venous thrombosis in three and eight times of skin-temperature change. X-film that was taken after operation for all patients showed scolisis in five cases. A follow up for 3-6 years (average 2.5 years) was performed in 84 cases, of which seven cases had chronic low-back pain, six scolisis and five kyphosis. No patient showed complications such as screw breakage, plate breakage, fixation device loosening and pseudo-articulation in thoracolumbar spine. Conclusions Many complications can be avoided if we master well anterior decompression and fixation technique of thoracolumbar fracture, reduce surgical trauma and give appropriate and rational guide for rehabilitation.