Human CCL5 mRNA

IL-27 is a pleiotropic cytokine with stimulatory/regulatory functions on a variety of immune cell lineages, including T lymphocytes. Here, researchers demonstrate that IL-27 can directly induce CCL5 production by T lymphocytes, especially CD8+ T cells, both in vitro and in vivo. IL-27-induced CCL5 production is dependent on IL-27R. In CD4+ T cells, IL-27-induced CCL5 production is primarily dependent on Stat1 activation, whereas in CD8+ T cells, Stat1 deficiency does not inhibit CCL5 induction. Chromatin immunoprecipitation assays showed that in the CCL5 promoter region, both putative Stat3 binding sites had significant binding to Stat3, while only one of the four Stat1 binding sites had moderate binding to Stat1. In tumor-bearing mice, IL-27 induced a large amount of CCL5 production by tumor-infiltrating T cells. IL-27-induced CCL5 appears to contribute to IL-27-mediated antitumor effects. This was shown by the reduced tumor inhibition in mice treated with both anti-CCL5 and IL-27. Furthermore, delivery of CCL5 mRNA into tumors using lipid nanoparticles significantly inhibited tumor growth. Thus, IL-27 induces T cells to produce large amounts of CCL5, which contributes to anti-tumor activity.

To determine the role of IL-27-induced CCL5 in tumor immunity, the researchers conducted the following two sets of experiments. First, B16.F10 tumor cells were subcutaneously inoculated into C57BL/6 mice and subsequently treated with AAV-IL-27 or AAV-ctrl virus on day 4. Then, mice were treated intraperitoneally with anti-CCL5 or control IgG2a antibodies on days 13, 17, 22, and 26. As shown in Figure 1A, although mice treated with AAV-ctrl/anti-CCL5 and AAV-ctrl/ctrl antibodies showed similar tumor growth kinetics, anti-CCL5 treatment significantly reduced the tumor suppression effect mediated by AAV-IL-27. This conclusion was based on the significant increase in tumor volume measured on days 26, 28, and 30. Second, the researchers prepared lipid nanoparticles encapsulating CCL5 mRNA (NP-CCL5 mRNA). In vitro cell culture experiments showed that NP-mediated delivery of CCL5 mRNA was effectively translated into CCL5 protein in B16.F10 cells (Figure 1B). Intratumoral injection of NP-CCL5 mRNA significantly inhibited tumor growth, as measured by a significant reduction in mean tumor volume (Figure 1C). Therefore, neutralization of CCL5 attenuated AAV-IL-27-mediated antitumor activity, while intratumoral delivery of CCL5 mRNA directly inhibited tumor growth.

Figure 1. IL-27-induced CCL5 production contributes to antitumor immunity. (Hu A, et al., 2022)