An aza-anthrapyrazole negatively regulates Th1 activity and suppresses experimental autoimmune encephalomyelitis

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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

BJ-2266 ameliorates experimental autoimmune encephalomyelitis through down-regulation of the JAK/STAT signaling pathway

CD4⁺ T cells differentiate into distinct effector subsets upon antigenic stimulation. Cytokines, and micro-environmental factors present during T-cell priming, direct differentiation of naïve CD4⁺ T cells into pro-inflammatory Th1 and Th17 cells. From extensive screening of 2,4,5-trimethylpyridin-3-ol derivatives with various functional groups at C(6)-position, BJ-2266, a 6-thioureido-derivative, showed potent inhibitory activity on in vitro T helper (Th)-cell differentiation. This compound inhibited IFN-γ and IL-17 production from polyclonal CD4⁺ T cells and ovalbumin (OVA)-specific CD4⁺ T cells that were activated by T-cell receptor (TCR) engagement. We assessed the inhibitory effect of BJ-2266 in experimental autoimmune encephalomyelitis (EAE). Our results suggest that BJ-2266 treatment significantly suppresses EAE disease progression with reduced generation of Th1 and Th17 cells. Notably, Th-cell differentiation was significantly suppressed by BJ-2266 treatment with no effect on apoptosis, activation and proliferation of activated T cells. Furthermore, adoptive transfer of BJ-2266 treated MOG-reactive Th1 and Th17 cells led to a lower EAE disease score and better clinical recovery from EAE. The underlying mechanism of BJ-2266 effect involved the inhibition of JAK/STAT phosphorylation that is critical for Th-cell differentiation. We conclude that BJ-2266 regulates the JAK/STAT pathway in response to cytokine signals and subsequently suppresses the differentiation of Th-cell responses.