As understanding of
cancer has deepened, increasing attention has been turned to the roles of psychological factors, especially chronic stress-induced depression, in the occurrence and development of
tumors. However, whether and how depression affects the progression of
gliomas are still unclear. In this study, we have revealed that chronic stress inhibited the recruitment of tumor-associated macrophages (TAM) and other immune cells, especially M1-type TAMs and CD8+ T cells, and decreased the level of proinflammatory
cytokines in
gliomas, leading to an immunosuppressive microenvironment and
glioma progression. Mechanistically, by promoting the secretion of stress
hormones, chronic stress inhibited the secretion of the
chemokine CCL3 and the recruitment of M1-type TAMs in
gliomas. Intratumoral administration of CCL3 reprogrammed the immune microenvironment of
gliomas and abolished the progression of
gliomas induced by chronic stress. Moreover, levels of CCL3 and M1-type TAMs were decreased in the
tumor tissues of
glioma patients with depression, and CCL3 administration enhanced the antitumor effect of anti-PD-1
therapy in orthotopic models of
gliomas undergoing chronic stress. In conclusion, our study has revealed that chronic stress exacerbates the immunosuppressive microenvironment and progression of
gliomas by reducing the secretion of CCL3. CCL3 alone or in combination with an anti-PD-1 may be an effective
immunotherapy for the treatment of
gliomas with depression. See related Spotlight by Cui and Kang, p. 514.