Figure 7.

Reinvigorated anti-tumor immunity upon treatments targeting CCL5-CCR5 axis. (A) A representative SEM image of MSV nanoparticle. (B) Microscopic analysis of the release of fluorescent siRNA. Alexa555-CCL5-siRNA was released from ESTA-MSV in murine BM in a time dependent manner (Green: ESTA-MSV, Red: Alexa555-CCL5-siRNA, Blue: nuclei). (C) 4T1 tumor growth curve under the treatment of PBS (Mock), MSV nanoparticles loaded with scrambled siRNA (Control) and MSV nanoparticles loaded with CCL5-targeting siRNA (CCL5-targeting) (1^st to 3^rd treatment indicated by black arrows. The red arrow indicates the time point of analysis). (D-E) Total 4T1 tumor burden (g) (D) and spleen weights (g) (E) of 3 groups described in 7C. (F) Flow cytometric analysis of Ly6C/ Ly6G expression on BM-MDSCs and intratumoral MDSCs in mice treated with control or CCL5-targeting nanoparticles. BM cells were gated on Gr-1⁺. (G-H) TAMs positive for CD11C, MHCII and VCAM1 (G) and SSC^low / CD8⁺ T cells (H) in 4T1 tumors carried by mice treated with mock, control or CCL5-targeting nanoparticles were counted via flow cytometer. (I) Flow cytometric analysis of GzmB and PD-1 expression by tumor-infiltrating CD8⁺ T cells sorted via CD8 microbeads. (J-L) Synergistic effects of CCL5-targeting nanoparticles and Maraviroc. Control group were treated with control nanoparticles (i.v) and DMSO (i.p.); the rest 2 groups were respectively treated with Maraviroc only (8mg/kg, i.p.) and Maraviroc combined with CCL5-targeting nanoparticles (i.v.).Tumor weights (J), growth curves (K) and counts of TAMs, tumor-infiltrating CD8⁺ T cells and GzmB⁺ / PD-1⁻ / CD8 ⁺ T cells (L) in 3 groups were shown as indicated. Data are representative of 2-4 independent experiments (n=4 to 8 / group).