IL-5 induces proliferation and activation of microglia via an unknown receptor.
While the effects of interleukin-3 (IL-3) and granulocyte macrophage-colony stimulating factor (GM-CSF) on microglia are well documented, very little is known about the effects of a related cytokine, interleukin-5 (IL-5). We therefore undertook studies to determine how IL-5 alters various aspects of microglial functioning. Treatment of microglia with IL-5 resulted in the induction of proliferation at levels similar to those induced by GM-CSF. IL-5 also increased cellular metabolism of microglial cells. To determine whether increased metabolism correlated with activation of microglia, we measured levels of nitrite, a breakdown product of nitric oxide. Treatment of microglial cultures with IL-5 increased nitrite levels, while GM-CSF treatment had no effect. Treatment of microglia with IL-5 did not cause activation of the signal transduction pathways linked to the classical IL-5 receptor, STAT5A/5B and ERK1 and ERK2. It is therefore likely that the effects of IL-5 on microglia are not mediated via the classical IL-5 receptor, but rather via a novel receptor.
Liva
S M
SM
Department of Neurobiology, Mental Retardation Research Center, Brain Research Institute, UCLA School of Medicine, Los Angeles, California 90095, USA.
de Vellis
J
J
D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D005562:Formazans / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D015848:Interleukin-5 / Q000494:pharmacology*; D017628:Microglia / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000502:physiology*; D018123:Receptors, Interleukin / Q000502:physiology; D053649:Receptors, Interleukin-5; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D005562:Formazans; D015848:Interleukin-5; D011956:Receptors, Cell Surface; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5; D016178:Granulocyte-Macrophage Colony-Stimulating Factor