AJP - Endocrinology and Metabolism, Vol 272, Issue 5 E908-E917, Copyright © 1997 by American Physiological Society
Altered energy balance and cytokine gene expression in a murine model of chronic infection with Toxoplasma gondii
D. Arsenijevic, L. Girardier, J. Seydoux, H. R. Chang and A. G. Dulloo
Department of Physiology, Faculty of Medicine, University of Geneva, Switzerland.
The temporal pattern of changes in energy balance and cytokine mRNA
expression in spleen and brain were examined in a mouse model of infection
with Toxoplasma gondii. During days 1-7 postinfection, food intake was
unaltered, but energy expenditure was significantly increased, and this was
associated with elevated tumor necrosis factor-alpha (TNF-alpha),
interleukin (IL)-1, IL-5, and interferon (IFN)-gamma. The hypermetabolic
state persisted during subsequent anorexia, whose onset coincided with
elevated IL-2, and at the end of the acute phase of cachexia, the dual
anorexic and hypermetabolic states were associated with the cytokines
examined: TNF-alpha, IL-1 beta, IL-2, IL-4, IL-5, IL-6, IL-10, and
IFN-gamma. In the chronic phase of the infection, the mice showed either
partial weight recovery (gainers) or no weight regain (nongainers). The
infected gainers, though still hypophagic, were no longer hypermetabolic,
and their cytokine mRNA was no longer elevated, except for TNF-alpha and
IL-10. In contrast, the infected nongainers continued to show both anoroxia
and hypermetabolism, which were associated with elevations in all cytokines
examined and particularly those of the TH2 profile (IL-4 and IL-5) and
IL-6. Taken together, these studies reveal a distinct pattern of cytokine
mRNA expression underlying 1) hypermetabolism vs. anorexia, 2) acute vs.
chronic cachexia, and 3) stable weight loss vs. partial weight recovery.
