BACKGROUND:M2 macrophages have the function of reducing inflammatory factors and promoting tissue healing.Therefore,how to regulate M2 polarization of macrophages has been a hot research topic in recent years,and some miRNAs have been found to have this function. OBJECTIVE:To investigate the effects of miR-378a on the polarization of the Raw264.7 macrophage cell line. METHODS:The M1 polarization of macrophages was induced by lipopolysaccharide and interferon-γ.Interleukin-4 induced M2 polarization and the expression of endogenous miR-378a in each cell type was detected using qRT-PCR to verify whether miR-378a was involved in the polarization of macrophages.By transfection with lentivirus as the vector of overexpression of miR-378a,the stable expression of miR-378a cell lines was screened.Macrophage M1 polarization was induced synergically by lipopolysaccharide and interferon-γ.Macrophage M2 polarization was induced by interleukin-4.The levels of M1/M2 polarization-related cytokines in the supernatant of the macrophage culture medium were determined by enzyme-linked immunosorbent assay.qRT-PCR was used to detect the polarization characteristics of M1/M2-type macrophages and the mRNA expression levels of related cytokines. RESULTS AND CONCLUSION:(1)The expression level of endogenous miR-378a in Raw264.7 cells of each group increased after macrophage polarization.(2)Compared with the non-transfected group,the expressions of proinflammatory cytokine-induced nitric oxide synthase,tumor necrosis factor-α,interleukin-6 and interleukin-1β in macrophage M1 induced polarization were significantly decreased in the miR-378a transfection group(P<0.05);the levels of inducible nitric oxide synthase,tumor necrosis factor-α and interleukin-6 in cell supernatant were also significantly decreased(P<0.05).(3)Compared with the non-transfected group,the expressions of CD206,interleukin-10 and arginase-I in macrophage M2 induced polarization were significantly increased(P<0.05);the levels of CD206 and interleukin-10 in cell supernatant were also significantly increased(P<0.05)in the miR-378a transfection group.(4)It is indicated that overexpression of miR-378a promotes the M2 polarization of macrophages and inhibits the M1 polarization of macrophages.

BACKGROUND:There are some problems such as bone fusion failure or peri-implant infection after implantation of pure titanium implants.Therefore,surface improvement of titanium implants has become a hot topic in research.Macrophages are an immune defense line of the body in response to external stimuli,and the relevant immune response of any biomaterials implanted in the body is related to macrophages. OBJECTIVE:The graphene oxide/hydroxyapatite composite coating on titanium alloy surface was prepared by electrochemical deposition method.The surface characteristics of the coating and the growth and polarization of macrophage RAW264.7 on the surface were analyzed. METHODS:The graphene oxide coating and graphene oxide/hydroxyapatite composite coating on titanium alloy surface was prepared by electrochemical deposition method.The physical properties of the coating were characterized.Pure titanium sheets(blank group),titanium sheets deposited with pure GO coating(control group)and titanium sheets deposited with graphene oxide/hydroxyapatite composite coating(experimental group)were co-cultured with macrophages RAW264.7,respectively.Cell proliferation was detected by CCK-8 assay and DAPI staining.Cell adhesion on the surface of titanium was observed by scanning electron microscopy,and cell polarization phenotype was detected by flow cytometry. RESULTS AND CONCLUSION:(1)Under scanning electron microscope,the pure titanium sheet showed directional scratches and a few punctate pits.After the pure graphene oxide coating was deposited,the surface of titanium sheet showed more cracks,gullies and particles of uneven size,and the wrinkle-like structure characterized by graphene oxide.After the composite coating was deposited,the surface of the titanium sheet was smooth,and the pellet size was more uniform.The water contact angle of composite coated titanium sheet was lower than that of pure titanium sheet and pure graphene oxide coated titanium sheet(P<0.05).(2)CCK-8 assay and DAPI staining showed that compared with the blank group and the control group,the cell proliferation in the experimental group was faster.Scanning electron microscopy showed that RAW264.7 cells all adhered to the surface of the three groups of titanium sheets.With the extension of culture time,cell morphology changed from round to spindle shape.After 7 days of culture,cells in the blank group extended short and few pseudopods;cells in the control group extended long and more pseudopods,and cells in the experimental group extended short and more pseudopods,and the overall cell fullness in the experimental group was the best.Flow cytometry results showed that the cells in the experimental group showed a higher proportion of M2 polarization in the anti-inflammatory direction.(3)These findings conclude that graphene oxide/hydroxyapatite composite coating has good physical,chemical,and biological properties.