Background
Interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) are expressed by microglia and infiltrating macrophages following ischemic stroke. Whereas IL-1beta is primarily neurotoxic in ischemic stroke, TNF-alpha may have neurotoxic and/or neuroprotective effects. We investigated whether IL-1beta and TNF-alpha are synthesized by overlapping or segregated populations of cells after ischemic stroke in mice.
Conclusion
Taken together, the results show that IL-1beta and TNF-alpha are produced by largely segregated populations of microglia and macrophages after ischemic stroke in mice. Our findings provide evidence of a functional diversity among different subsets of microglia and macrophages that is potentially relevant to future design of anti-inflammatory therapies in stroke.
Methods
We used flow cytometry and immunohistochemistry to examine cellular co-expression of IL-1beta and TNF-alpha at 6, 12 and 24 hours after permanent middle cerebral artery occlusion in mice, validating the
Results
We found that IL-1beta and TNF-alpha were expressed in largely segregated populations of CD11b+CD45dim microglia and CD11b+CD45high macrophages, with cells expressing both cytokines only rarely. The number of Gr1+ granulocytes producing IL-1beta or TNF-alpha was very low, and we observed no IL-1beta- or TNF-alpha-expressing T cells or astrocytes.