Pearson’s correlation coefficients and p-values.

Although Schwann cells have been found to play a key role in inflammation and repair following nerve injury, the exact pathway is still unknown. To explore the mechanism by which Schwann cells exert their effects in the neuron microenvironment, we investigated two main inflammatory pathways: the NF-κB and cAMP pathways, and their downstream signaling molecules. In this study, lipopolysaccharide (LPS), a bacterial endotoxin, was used to activate the NF-κB pathway, and forskolin, a plant extract, was used to activate the cAMP pathway. The rat RT4-D6P2T Schwann cell line was treated with 0.1, 1, or 10 μg/mL of LPS, with or without 2 μM of forskolin, for 1, 3, 12, and 24 hours to determine the effects of elevated cAMP levels on LPS-treated cell viability. To investigate the effects of elevated cAMP levels on the expression of downstream signaling effector proteins, specifically NF-κB, TNF-α, AKAP95, and cyclin D3, as well as TNF-α secretion, RT4-D6P2T cells were incubated in the various treatment combinations for a 3-hour time period. Overall, results from the CellTiter-Glo viability assay revealed that forskolin increased viability in cells treated with smaller doses of LPS for 1 and 24 hours. For all time points, 10 μg/mL of LPS noticeably reduced viability regardless of forskolin treatment. Results from the Western blot analysis revealed that, at 10 μg/mL of LPS, forskolin upregulated the expression of TNF-α despite a downregulation of NF-κB, which was also accompanied by a decrease in TNF-α secretion. These results provide evidence that cAMP might regulate TNF-α expression through alternate pathways. Furthermore, although cAMP activation altered AKAP95 and cyclin D3 expression at different doses of LPS, there does not appear to be an association between the expression of AKAP95 or cyclin D3 and the expression of TNF-α. Exploring the possible interactions between cAMP, NF-κB, and other key inflammatory signaling pathways might reveal a potential therapeutic target for the treatment of nerve injury and inflammation.

尽管施万细胞（Schwann cells）已被证实可在神经损伤后的炎症反应与修复过程中发挥关键调控作用，但其具体分子通路仍未明确。为探究施万细胞在神经元微环境中发挥生物学功能的具体机制，本研究聚焦于两大核心炎症通路——核因子κB（NF-κB）与环磷酸腺苷（cAMP）通路，及其下游信号分子。本研究采用细菌内毒素脂多糖（lipopolysaccharide, LPS）激活NF-κB通路，使用植物提取物毛喉素（forskolin）激活cAMP通路。将大鼠RT4-D6P2T施万细胞系以0.1、1或10 μg/mL的LPS进行处理，并分别联合或不联合2 μM的毛喉素，分别孵育1、3、12与24小时，以明确cAMP水平升高对LPS处理细胞存活率的影响。为探究cAMP水平升高对下游信号效应蛋白（具体包括NF-κB、肿瘤坏死因子α（TNF-α）、A激酶锚定蛋白95（AKAP95）以及细胞周期蛋白D3（cyclin D3））的表达，以及TNF-α分泌的调控作用，本研究将RT4-D6P2T细胞以上述不同处理组合孵育3小时。总体而言，CellTiter-Glo细胞存活率检测结果显示，在1小时与24小时时间点，毛喉素可提升低剂量LPS处理细胞的存活率；而在所有检测时间点中，10 μg/mL的LPS均可显著降低细胞存活率，且该效应不受毛喉素处理的影响。蛋白质免疫印迹（Western blot）分析结果表明，在10 μg/mL LPS处理条件下，毛喉素虽可下调NF-κB的表达，但却上调了TNF-α的表达，同时伴随TNF-α分泌量的下降。上述结果证实，cAMP或可通过替代通路调控TNF-α的表达。此外，尽管cAMP激活可在不同LPS剂量下改变AKAP95与cyclin D3的表达，但AKAP95或cyclin D3的表达与TNF-α的表达之间似乎并无显著关联。进一步探究cAMP、NF-κB与其他关键炎症信号通路间的潜在相互作用，或可为神经损伤与炎症性疾病的治疗发掘潜在的药物靶点。