For years, nearly all research mice have been housed at temperatures that feel relatively comfortable for men and women wearing scrubs, gowns, masks and shoe covers—about 22°C or 72°F. But mice generally prefer a warmer environment—30°C or 86°F.
TEMPERATURE MAKES A DIFFERENCE
This often-overlooked variable can be enough to change metabolic rates and immune responses in mice, as well as other factors.
“By housing mice in a thermoneutral environment, we can observe much more human-like disease development and progression,” Divanovic says. “The disease itself is more robust. We can see fibrosis in the liver and the development of certain immune cells and markers that are present in human disease but often are not observed in mouse models.”
“By housing mice in a thermoneutral environment, we can observe much more human-like disease development and progression.”
Investigators also see human-like responses in the intestinal microbiome that have not been observed in mice housed at cooler temperatures. Meanwhile, for the first time, researchers can induce obesity and NAFLD in female mice, which will finally allow deeper analysis of hormonal factors that may affect the condition as well as the multi-generational effects of maternal obesity.
Results reported in the study included lower stress-driven corticosterone production among the warmer mice, augmented proinflammatory immune responses, markedly exacerbated high-fat diet pathogenesis, depletion of Gram-negative microbiota, hematopoietic cell deletion of Toll-like receptor 4 (TLR4), and inactivation of the interleukin-17 (IL-17) axis.