A silk elastin-like protein (SELP) is an artificial compound with silk fibroin-like and elastin-like tandem repeats. The objective of this study is to evaluate the influence of SELP on the polarization of mouse bone marrow-derived macrophages. When the macrophages of inflammation-type (M1) were cultured with different concentrations of SELP solution, the secretion of a pro-inflammatory cytokine, tumor necrotizing factor (TNF)-α, was significantly suppressed at the higher concentrations. In addition, the secretion of an anti-inflammation cytokine, interleukin (IL)-10, was significantly enhanced from the macrophage of an original type (M0). By the incubation with soluble SELP, the morphology of M0-and M1-type macrophages changed to be of a round shape with a large size. Following incubation with the sponge of SELP, the M0-type macrophages secreted IL-10 with time. When injected into an air pouch of mice subcutis which had been prepared by the injection of air, the SELP sponge and 5 wt % of SELP solution induced IL-10 secretion to a significantly high extent compared with the saline injection. Cells isolated from the air pouch 24 h after the injection were stained by the CD206 of a M2 marker. It is concluded that the SELP itself in solution has an ability to induce the anti-inflammation M2-type macrophages.

A silk elastin-like protein (SELP) is an artificial compound with silk fibroin-like and elastin-like tandem repeats. The objective of this study is to evaluate the influence of SELP on the polarization of human monocytoma cell line (THP-1)-derived macrophages. When the macrophages of inflammation-type (M1) were cultured with different concentrations of SELP solution, the secretion of a pro-inflammatory cytokine, tumor necrotizing factor (TNF) -α was significantly suppressed at the higher concentrations. In addition, the secretion of an anti-inflammation cytokine, interleukin (IL)-10, was significantly enhanced from the macrophage of M0-, M1-, and M2-types. By the incubation with soluble SELP, the morphology of M2-type macrophages changed to be of an extended shape. Following incubation with the sponge of SELP, M0-type macrophages secreted IL-10 with time. It is concluded that the SELP itself in solution has an ability to induce the anti-inflammation of M2-type macrophages.

As one imaging method to evaluate monocyte–macrophage differentiation, cationized gelatin nanospheres incorporating a molecular beacon (MB) (cGNSMB) were designed. Cationized gelatin nanospheres (cGNS) of different apparent sizes were prepared by the conventional coacervation method, and then the MB of CD204 was incorporated into cGNS to prepare cGNSMB. When three types of cGNSMB were cultured with human monocytoma (THP-1) cells, the cGNSMB with a 110 nm diameter showed the highest MB delivery efficiency. In addition, no influence on the monocyte–macrophage differentiation was observed in terms of CD204 gene expression and cell viability. After incubation with cGNS incorporating CD204 MB (cGNSCD204), THP-1 cells were stimulated by phorbol 12-myristate 13-acetate (PMA) for monocyte differentiation into macrophages. The fluorescence intensity of macrophages increased with the incubation time. In contrast, the fluorescence intensity of macrophages incubated with MB alone was not changed. On the other hand, there was no change in the fluorescence intensity of original THP-1 cells cultured with cGNSCD204. It is concluded that the cGNSCD204 are promising to trace the differentiation of THP-1 cells into macrophages in their live condition.