IL-10-producing B cells limit CNS inflammation and infarct volume after experimental stroke in mice (P1090)

Abstract

Abstract Clinical stroke induces inflammatory processes leading to cerebral injury. IL-10 expression is elevated during major CNS diseases and limits inflammation in the brain. Recent evidence demonstrated that absence of B cells led to larger infarct volumes and increased numbers of activated T cells, monocytes and microglial cells in the brain, thus implicating a regulatory role of B cell subpopulations in limiting CNS damage from stroke. The aim of this study was to determine whether the IL-10-producing regulatory B cell subset can limit CNS inflammation and reduce infarct volume following ischemic stroke in B-cell deficient (μMT-/-) mice. Five million IL-10-producing B cells were obtained from IL-10-GFP reporter mice and transferred i.v. to μMT-/- mice. After 24 h from this transfer, recipients were subjected to 60 min of middle cerebral artery occlusion (MCAO) followed by 48 h of reperfusion. Compared to vehicle-treated controls, the IL-10+ B-cell-replenished μMT-/- mice had reduced infarct volume and fewer infiltrating activated T cells and monocytes in the affected brain hemisphere. These effects in CNS were accompanied by significant increases in regulatory T cells and expression of the co-inhibitory receptor, PD-1, in the periphery. These novel observations demonstrate both immunoregulatory and protective functions of IL-10-secreting B cells in MCAO that potentially could impart significant benefit for stroke patients in the clinic.