CNS-derived interleukin-4 is essential for the regulation of autoimmune inflammation and induces a state of alternative activation in microglial cells.
Regulation of inflammation in the CNS is essential to prevent irreversible cellular damage that can occur in neurodegenerative diseases such as multiple sclerosis (MS). We investigated the role of interleukin-4 (IL-4) in regulating CNS inflammation using the animal model of MS, experimental autoimmune encephalomyelitis (EAE). We found that CNS-derived IL-4 was a critical regulator because mice with a deficiency in IL-4 production in the CNS, but not the periphery, had exacerbated EAE associated with a significant increase in the absolute number of infiltrating inflammatory cells. We also found that CNS-resident microglial cells in both the resting and activated state produced the protein Ym1, which is a marker of alternatively activated macrophages (aaMphis), in an IL-4-dependent manner. This aaMphi phenotype extended to the lack of nitric oxide (NO) production by activated microglial cells, which is a marker of classically activated macrophages. We also show that IL-4 induced the expression of Ym1 in peripheral infiltrating macrophages, which also produce NO. Thus, macrophages that migrate into the CNS exhibit a dual phenotype. These data indicate that IL-4 production in the CNS is essential for controlling autoimmune inflammation by inducing a microglial cell aaMphi phenotype. Macrophages that have undergone alternative activation have been shown to be important in tissue repair; thus, our results suggest a new role for microglial cells in the regulation of inflammation in the CNS.
Ponomarev
Eugene D
ED
BloodCenter of Wisconsin, Blood Research Institute, Milwaukee, Wisconsin 53201-2178, USA.
Maresz
Katarzyna
K
Tan
Yanping
Y
Dittel
Bonnie N
BN
D000818:Animals; D002478:Cells, Cultured; D002490:Central Nervous System / Q000378:metabolism* / Q000473:pathology; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D005434:Flow Cytometry; D005786:Gene Expression Regulation / Q000235:genetics / Q000502:physiology; D036341:Intercellular Signaling Peptides and Proteins; D015847:Interleukin-4 / Q000172:deficiency / Q000502:physiology*; D037102:Lectins / Q000378:metabolism; D008264:Macrophages; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017628:Microglia / Q000502:physiology*; D020932:Nerve Growth Factor / Q000235:genetics / Q000378:metabolism; D009569:Nitric Oxide; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D011956:Receptors, Cell Surface / Q000172:deficiency; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism; D053662:Interleukin-4 Receptor alpha Subunit
D036341:Intercellular Signaling Peptides and Proteins; D015847:Interleukin-4; D037102:Lectins; D020932:Nerve Growth Factor; D009569:Nitric Oxide; D011506:Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D001619:beta-N-Acetylhexosaminidases; C504002:Il4ra protein, mouse; D053662:Interleukin-4 Receptor alpha Subunit; C413576:Retnla protein, mouse; C429541:Chil3 protein, mouse