AJP - Regulatory, Integrative and Comparative Physiology, Vol 271, Issue 1 149-R156, Copyright © 1996 by American Physiological Society
Microglia digest Staphylococcus aureus into low molecular weight biologically active compounds
E. F. Fincher 4th, L. Johannsen, L. Kapas, S. Takahashi and J. M. Krueger
Department of Physiology and Biophysics, University of Tennessee, Memphis 38163, USA.
Excess sleep and fever are central nervous system (CNS) facets of the acute
phase response; these responses are induced by microbial products, such as
muramyl peptides, via their ability to enhance cytokine production.
Although peripheral macrophages are known to digest bacteria, thereby
releasing muramyl peptides that, in turn, stimulate cytokine production, it
was unknown whether CNS phagocytes such as microglia also had this
capacity. Primary cultures of microglia were allowed to phagocytize and
digest Staphylococcus aureus radiolabeled with a cell wall-specific marker.
Radiolabeled low molecular weight substances released into the culture
medium were partially purified and tested for the ability to induce excess
sleep, fever, and cytokine production. These substances increased non-rapid
eye movement sleep, electroencephalographic slow-wave activity, and brain
temperature after intracerebroventricular injection into rabbits. They also
induced interleukin-1, tumor necrosis factor, and the interleukin-1
receptor antagonist production in human monocytes. Results suggest that
microglia perform fundamental macrophage functions and further implicate
microglia as resident immunocompetent cells.
