Chronic restraint stress impairs T-cell immunity and promotes tumor. progression in mice

FRICK LR; BARREIRO ARCOS ML; RAPANELLI M; ZAPPIA MP; BROCCO MA; MONGINI C; GENARO AM; CREMASCHI GA

STRESS

Taylor & Francis Health Sciences

Año: 2009 vol. 12 p. 134 - 143

1025-3890

Chronic stress is involved in the onset of specific psychiatric diseases such as major depression. Long-term exposure to stressful situations also affects the immune system. T cell response is an important component of antitumoral immunity. Hence, impairment of the immune function induced by a chronic stressor has been postulated to alter the immunosurveillance of tumors, thus leading to a worse neoplastic prognosis. Here we show that chronic restraint stress affects T helper regulation of antitumoral immunity, evidenced by a reduced mitogen-induced T cell proliferation, a reduction of CD4+ T lymphocytes and a decrease in Tumor Necrosis Factor - alpha (TNF-a) and Interferon - gamma (IFN-g) expression. Additionally, animals subjected to chronic restraint stress displayed an enhancement of tumor growth in a syngeneic lymphoma model. In addition, these effects on immunity and cancer prognosis were prevented by chronic fluoxetine administration, an antidepressant that selectively inhibits serotonin reuptake. These results suggest that chronic exposure to stress promotes tumor growth probably by depressing T-cell mediated immunity. The possibility that depressive-like state induced by the stressor would be participating in these effects is also discussed. The T-cell immunity enhancement as well as the tumor growth slow down by fluoxetine; emphasize the importance of the therapeutic management of the stress and stress-associated depression to improve the prognosis of cancer patients.