The Establishment Of Lymph Node Targeting Nucleic Acid Delivery System And Its Application In The Treatment Of Tumor Metastasis

Tumor metastasis is the main cause of death in malignant tumor patients.Inhibition of migration and invasion of cancer cells has been the focus of many studies.Lymph node metastasis is an early event in the spread of most solid tumors.It is also a major pathway for metastasis of melanoma and breast cancer.SCS macrophages are lymphatic node specific macrophages located in the cortical lymph sinus of lymph nodes.Siglec-1(CD 169)is highly expressed on their membrane surface which has very high affinity for cationic natural polysaccharide carriers containing galactose residues.SCS macrophages mainly capture antigens by filtering into lymph and presenting it to cytotoxic T cells(CTL),secreting a series of cytokines to activate NK cells and promoting the differentiation of Th1 cells to play an anti-tumor effect.As an ODN,CpG with special sequence can activate TLR9 related signaling pathways,which activates a series of anti-tumor immune responses downstream.It is theoretically possible to destroy the immunosuppressive environment in the lymph nodes by drug therapy,and to resetore the inherent immune response of the lymph nodes to block the metastasis.In this study,we constructed a nucleic acid delivery system,the nucleic acid delivery system is a complex(named as C-agarose&CpG)consisting of a cationic modified agarose gel,which is mainly composed of galactose,and a CpG nucleic acid drug.CD 169 is highly expressed on the surface of SCS macrophages which has a high affinity with galactose residues.In vivo,the results of tissue distribution experiments showed that the carrier mainly transported CpG into CD169 macrophages in lymph nodes.In vitro,the experiment results of cell transfection showed that the C-agarose can send CpG efficiently into CD 169 macrophages.And this efficient transport depends mainly on CD169 molecular.The flow results showed that CpG increased the ratio of T Cells,Dendritic Cells(DC)and NK and promoted the expression of cytokines IFN-gamma,IL-2 and Gzms-B.In the 4T1 and B16 tumor-bearing mice model,after C-agarose&CpG treatmented,we also examined the changes of the immune cells and cytokines in the lymph nodes.Similar to the results of cell experiments,we found that it increased the ratio of T Cells,DC Cells and NK Cells and increased the expression of IL-1 ??TNF-??GM-CSF?IFN-??IL-2 and Gzms-B.And C-agarose&CpG treatment could effectively inhibited the metastasis and growth of tumors and obviously prolonged the survival time of mice.In conclusion,the drug delivery strategy based on the targeting of lymph nodes to deliver CpG can significantly block the metastasis of the tumor through the lymph nodes and has achieved good therapeutic effect in the treatment of tumor model mice.This nonoperative interventional immunotherapy for lymph nodes can provide a new therapeutic strategy for blocking lymphatic metastasis of tumors and has potential for clinical appalication.