Chronic cold-stress suppresses chemokine production and CD8+ T cell infiltration in the tumor microenvironment (TUM7P.1024)

Abstract Recently it was reported that maintenance of mice at thermoneutral temperatures (TT, the temperature at which basal metabolism is sufficient to maintain body temperature, 30oC) enhanced antitumor immune responses and reduced tumor growth, relative to standard vivarium temperatures (ST, 22oC). We hypothesized that mice maintained at ST may have impaired production of T cell chemoattractant cytokines and subsequent T cell infiltration. In mice bearing breast tumors or solid or metastatic-like melanomas, intratumoral expression of CXCL9 and CXCL10 (CXCR3-cognate chemokines) was enhanced by maintenance of hosts in TT conditions. Further, tumors of TT-housed mice contained increased numbers of CD8+ T cells. We further hypothesized that the effect of temperature on T cell chemokine pathways may be a result of chronic cold stress, which may induce norepinephrine (NE) production and subsequent activation of β-adrenergic signaling pathways. We observed that pharmacologic blockade of β-adrenergic receptors in mice bearing solid or metastatic-like melanomas recapitulated the increased intratumoral expression of CXCL9 and CXCL10 and increased CD8+ T cell numbers. Because melanoma cells express β-adrenergic receptors, we suggest that chronic cold stress may induce systemic NE production, leading to tumor local activation of receptors and inhibition of tumor-derived chemokine production. These studies suggest potential interventions to improve existing T cell-based immunotherapies.