Scutellarin Exerts Anti-Inflammatory Effects in Activated Microglia/Brain Macrophage in Cerebral Ischemia and in Activated BV-2 Microglia Through Regulation of MAPKs Signaling Pathway

• Published in: Neuromolecular medicine 2020-06, Vol.22 (2), p.264-277
• Main Authors: Chen, Hao-Lun, Jia, Wen-Ji, Li, Hong-E, Han, Hong, Li, Fan, Zhang, Xiao-Li-Na, Li, Juan-Juan, Yuan, Yun, Wu, Chun-Yun
• Format: Article
• Language: English
• Subjects: Anti-inflammatory agents; Biomedical and Life Sciences; Biomedicine; Cerebral blood flow; IL-1β; Immunofluorescence; Inflammation; Interleukin 1; Internal Medicine; Ischemia; Lipopolysaccharides; Macrophages; MAP kinase; Microglia; Neurology; Neuroprotection; Neurosciences; Nitric oxide; Nitric-oxide synthase; Original Paper; p38 Protein; Signal transduction; Tumor necrosis factor-TNF; Tumor necrosis factor-α
• ISSN: 1535-1084; 1559-1174
• DOI: 10.1007/s12017-019-08582-2

Background Scutellarin, an herbal compound, can effectively suppress the inflammatory response in activated microglia/brain macrophage(AM/BM) in experimentally induced cerebral ischemia; however, the underlying mechanism for this has not been fully clarified. We sought to elucidate if scutellarin would exert its anti-inflammatory effects on AM/BM through the MAPKs pathway. Materials and Methods Western blot and immunofluorescence labeling were used to determine the expression of the MAPKs pathway in AM/BM in rats subjected to middle cerebral artery occlusion (MCAO) also in lipopolysaccharide (LPS)-activated BV-2 microglia in vitro. Furthermore, expression of p-p38 along with that of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta(IL-1β), and inducible nitric oxide synthase (iNOS) in LPS-activated microglia subjected to pretreatment with p38 inhibitor SB203580, p38 activator sc-201214, scutellarin, or a combination of them was evaluated. Findings Scutellarin markedly attenuated the expression of p-p38, p-JNK in AM/BM in MCAO rats and in vitro. Conversely, p-ERK1/2 expression level was significantly increased by scutellarin. Meanwhile, scutellarin suppressed the expression of proinflammatory mediators including iNOS, TNF-α, and IL-1β in AM/BM. More importantly, SB203580 suppressed p-p38 protein expression level in LPS-activated BV-2 microglia that was coupled with decreased expression of proinflammatory mediators (TNF-α, iNOS) in LPS-activated BV-2 microglia. However, p38 activator sc-201214 increased expression of proinflammatory mediators TNF-α, iNOS, and IL-1β. Interestingly, the decreased expression of both proinflammatory markers by p38 MAPK inhibitor and increased expression of proinflammatory markers by p38 MAPK activator were compatible with that in BV-2-activated microglia pretreated with scutellarin. Conclusions The results suggest that scutellarin down-regulates the expression of proinflammatory mediators in AM/BM through suppressing the p-JNK and p-p38 MAPKs. Of note, the anti-inflammatory effect of p38 MAPK inhibitor and scutellarin is comparable. Besides, p38 MAPKs activator reverses the effect of scutellarin. Additionally, scutellarin increases p-ERK1/2 expression that may be neuroprotective.