Department of Infectious Diseases, Medical Microbiology and Hygiene, Heidelberg University, Heidelberg, Germany.
Virulence. 2023 Dec;14(1):2254599. doi: 10.1080/21505594.2023.2254599.
Chronic implant-related bone infections are a severe complication in orthopaedic surgery. Biofilm formation on the implant impairs the immune response, leading to bacterial persistence. In a previous study, we found that (SA) induced interferon regulatory factor 3 (IRF3) activation and expression only in its planktonic form but not in the biofilm. The aim of this study was to clarify the role of the stimulator of interferon genes (STING) in this process. We treated RAW 264.7 macrophages with conditioned media (CM) generated from planktonic or biofilm cultured SA in combination with agonists or inhibitors of the cyclic GMP-AMP synthase (cGAS)/STING pathway. We further evaluated bacterial gene expression of planktonic and biofilm SA to identify potential mediators. STING inhibition resulted in the loss of IRF3 activation and induction in SA planktonic CM, whereas STING activation induced an IRF3 dependent IFN-β response in SA biofilm CM. The expression levels of virulence-associated genes decreased during biofilm formation, but genes associated with cyclic dinucleotide (CDN) synthesis did not correlate with induction. We further observed that cGAS contributed to induction by SA planktonic CM, although cGAS activation was not sufficient to induce expression in SA biofilm CM. Our data indicate that the different degrees of virulence associated with SA planktonic and biofilm environments result in an altered induction of the IRF3 mediated IFN-β response via the STING pathway. This finding suggests that the STING/IRF3/IFN-β axis is a potential candidate as an immunotherapeutic target for implant-related bone infections.
慢性植入物相关骨感染是骨科手术中的一种严重并发症。植入物上生物膜的形成会损害免疫反应，导致细菌持续存在。在之前的研究中，我们发现 （SA） 仅在其浮游形式而不是生物膜中诱导干扰素调节因子 3 (IRF3) 的激活和 表达。本研究旨在阐明干扰素基因刺激物 (STING) 在这一过程中的作用。我们用浮游或生物膜培养的 SA 产生的条件培养基 (CM) 处理 RAW 264.7 巨噬细胞，同时用 cGAS/STING 通路的激动剂或抑制剂处理。我们进一步评估了浮游和生物膜 SA 的细菌基因表达，以确定潜在的介质。STING 抑制导致 SA 浮游 CM 中 IRF3 激活和 诱导的丧失，而 STING 激活在 SA 生物膜 CM 中诱导 IRF3 依赖性 IFN-β 反应。生物膜形成过程中，毒力相关基因的表达水平下降，但与环二核苷酸 (CDN) 合成相关的基因与 诱导无关。我们进一步观察到，尽管 cGAS 激活不足以诱导 SA 生物膜 CM 中的 表达，但 cGAS 对 SA 浮游 CM 中的 诱导有贡献。我们的数据表明，SA 浮游和生物膜环境中不同程度的毒力导致 STING 通路介导的 IFN-β 反应的 IRF3 调节诱导发生改变。这一发现表明，STING/IRF3/IFN-β 轴是治疗植入物相关骨感染的潜在免疫治疗靶点。
