Strawberry notch homolog 2 regulates the response to interleukin-6 in the central nervous system

Background The cytokine interleukin-6 (IL-6) modulates a variety of inflammatory processes and, context depending, can mediate either pro- or anti-inflammatory effects. Excessive IL-6 signalling in the brain is associated with chronic inflammation resulting in neurodegeneration. Strawberry notch homolog 2 (Sbno2) is an IL-6-regulated gene whose function is largely unknown. Here we aimed to address this issue by investigating the impact of Sbno2 disruption in mice with IL-6-mediated neuroinflammation. Methods Mice with germline disruption of Sbno2 (Sbno2(-/-)) were generated and crossed with transgenic mice with chronic astrocyte production of IL-6 (GFAP-IL6). Phenotypic, molecular and transcriptomic analyses were performed on tissues and primary cell cultures to clarify the role of SBNO2 in IL-6-mediated neuroinflammation. Results We found Sbno2(-/-) mice to be viable and overtly normal. By contrast GFAP-IL6 x Sbno2(-/-) mice had more severe disease compared with GFAP-IL6 mice. This was evidenced by exacerbated neuroinflammation and neurodegeneration and enhanced IL-6-responsive gene expression. Cell culture experiments on primary astrocytes from Sbno2(-/-) mice further showed elevated and sustained transcript levels of a number of IL-6 stimulated genes. Notably, despite enhanced disease in vivo and gene expression both in vivo and in vitro, IL-6-stimulated gp130 pathway activation was reduced when Sbno2 is disrupted. Conclusion Based on these results, we propose a role for SBNO2 as a novel negative feedback regulator of IL-6 that restrains the excessive inflammatory actions of this cytokine in the brain.

Automated summary

This study demonstrates that SBNO2 acts as a novel negative feedback regulator of IL-6 in the brain, restraining its excessive inflammatory actions and providing protection against neuroinflammation and neurodegeneration.