Abstract:

Objective To investigate the effect of collagen on M1 macrophage polarization in vivo and in vitro study. Methods Immunofluorescence was used to detect the distribution of macrophages in clinical colorectal tumor, and the distribution of macrophages in orthotopic carcinoma model mice. Masson staining was used to detect collagen fibers in tumor tissues. The mouse peritoneal macrophages were cultured on the cell culture dish coated by different concentration of type Ⅰ collagen, then determine the gene expression of tumor necrosis factor（TNF）, inducible nitric oxide synthase（iNOS）, CD163, CD206 by using Real-time PCR method . Results Macrophages were mainly distributed in the stroma of tumor tissue in human colon cancer tissue and mouse carcinoma samples, tumor-associated macrophages there were mainly M1-type, while macrophages in the parenchymal area of tumor tissue were mainly M2 macrophages; Type Ⅰ collagen induces macrophages polarization into M1 phenotype and inhibits the macrophages to the tumor-promoting M2-type in vitro; Masson staining showed that collagen fibers were mainly distributed in the stroma of tumor tissue both in human and mouse tumor, and collagen fibers around the tumor parenchymal cells were less, however, collagen fibers were abundant in the stroma of tumor tissue. Conclusion Type Ⅰ collagen induces the polarization of macrophages to M1 phenotype, while the decrease of collagen fibers around the tumor parenchymal cells may be one of the related factors for the M2 polarization of macrophages which can promote the progression and invasion and metastasis of tumors.

Key words: Type Ⅰ collagen, Macrophage, Colorectal cancer, Polarization, Real-time PCR, Human, Mouse