Targeting macrophages by an aza-anthrapyrazole to ameliorate experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is an immune-mediated neurodegenerative disease in the central nerve system, in which both innate and adaptive immune cells are involved. BBR3378, an aza-anthrapyrazole prevents experimental autoimmune encephalomyelitis (EAE), an inflammatory condition similar to MS, by antagonizing T cell autoimmune responses. Here, we report BBR3378's regulatory effect on macrophages.

EAE was induced in ten-week-old female C57BL/6 mice by immunization with myelin oligodendrocyte glycoprotein peptides followed by BBR3378 or sham treatment administered intraperitoneally, and clinical signs were assessed using a 0-5 scoring system. These mice were subjected to serum ELISA for cytokine IFNγ and TNFα levels, RT qPCR analysis of macrophage markers in isolated monocytes, and flow cytometry analysis for macrophage infiltration in the brain. Macrophages derived from primary monocytes and macrophage cell line RAW 264.7 were used to investigate BBR3378's effect on LPS-stimulated pro-inflammatory cytokine induction. RAW 264.7 cells expressing NF-κB-driven luciferase reporter were treated with LPS with or without BBR3378, and luciferase assays performed to assess the inhibition on NF-κB activation. LPS-induced activation of mitogen-activated protein kinases (MAPKs) with or without the presence of BBR3378 was also investigated by Western blot analysis.

BBR3378 down-regulated cytokine-induced macrophage differentiation and activation in EAE mice, contributing to protection against macrophage infiltration in the brain and clinical symptoms from EAE. Treating macrophages with BBR3378 counteracted LPS-induced cytokine production via blocking activation of key signal molecules mediating inflammatory responses, such as NF-κB and MAPKs.

These data suggest that in addition to T cells, BBR3378 can also target macrophages to attenuate the inflammation associated with EAE.