Japanese encephalitis virus induces matrix metalloproteinase‐9 in rat brain astrocytes via NF‐κB signalling dependent on MAPKs and reactive oxygen species

Abstract

BACKGROUND AND PURPOSEJapanese encephalitis virus (JEV) is a member of the family Flaviviridae and JEV infection is a major cause of acute encephalopathy in children, which destroys cells in the CNS, including astrocytes and neurons. However, the detailed mechanisms underlying the inflammatory action of JEV are largely unclear. EXPERIMENTAL APPROACHThe effect of JEV on the expression of matrix metalloproteinase (MMP)-9 was determined by gelatin zymography, Western blot analysis, real-time PCR and promoter assay. The involvement of the NADPH oxidase and reactive oxygen species (ROS), MAPKs, and the transcription factor NF-kB in these responses was investigated by using selective pharmacological inhibitors and transfection with appropriate siRNAs. KEY RESULTSJEV induced the expression of the pro-form of MMP-9 in rat brain astrocytes (RBA-1 cells). In RBA-1 cells, JEV induced MMP-9 expression and promoter activity, which was inhibited by pretreatment with inhibitors of NADPH oxidase (diphenylene iodonium chloride or apocynin), MAPKs (U0126, SB203580 or SP600125) and a ROS scavenger (N-acetylcysteine), or transfection with siRNAs of p47 phox , ERK1, JNK2 and p38. In addition, JEV-induced MMP-9 expression was reduced by pretreatment with an inhibitor of NF-kB (helenalin) or transfection with p65 siRNA. Moreover, JEV-stimulated NF-kB activation was inhibited by pretreatment with the inhibitors of NADPH oxidase and MAPKs. CONCLUSIONS AND IMPLICATIONSMMP-9 expression induced by JEV infection of RBA-1 cells was mediated through the generation of ROS and activation of p42/p44 MAPK, p38 MAPK and JNK1/2, leading to NF-kB activation. AbbreviationsBBB, blood-brain barrier; BCA, Bicinchoninic acid; COX-2, cyclooxygenase-2; ECM, extracellular matrix; GFAP, glial fibrillary acid protein; HIV, human immunodeficiency virus; iNOS, inducible nitric oxide synthase; IL-8, interleukin-8; JEV, Japanese encephalitis virus; MMP-9, matrix metalloproteinase-9; PBS, phosphate-buffered saline; TNF-a, tumor necrosis factor-a

Upregulated Expression of Matrix Metalloproteinases and Tissue Inhibitors of Matrix Metalloproteinases in BALB/c Mouse Brain Challenged with Japanese Encephalitis Virus

“…Recently, Tung et al [64] demonstrated that JEV-induced MMP-9 expression occurs at transcriptional and translational levels, which supports our data. They also demonstrated that JEV stimulated MMP-9 expression that was mediated through the generation of ROS and activation of NADPH oxidase, p42/p44 MAPK, p38 MAPK, JNK1/2, and NF-ĸB in RBA-1 cells.…”

Ginkgo biloba extract inhibits oxidized low-density lipoprotein (oxLDL)-induced matrix metalloproteinase activation by the modulation of the lectin-like oxLDL receptor 1-regulated signaling pathway in human umbilical vein endothelial cells

“…A previous study determined that an increased level of ROS could induce the upregulation of MMPs by MAPK/NF-kB signaling. 22 To investigate whether NF-kB upstream modulators participate in the inhibitory functions of GbE-mitigated oxLDL-caused activation of MMPs, endothelial cells were pretreated with pharmacologic inhibitors of ROS (DPI), Ca þþ , (1,2-bis(o-aminophenoxy) ethane-N,N,N 0 ,N 0 -tetraacetic acid [BAPTA]), PKC-a/b (Gö6976), and ERK (PD98059). As demonstrated in Fig 6, the expression of oxLDL-promoted ERK phosphorylation and NF-kB activation, which is downstream of ERK phosphorylation, was conspicuously restrained in cells pretreated with GbE, DPI, BAPTA, Gö6976, and PD98059.…”

Infection of Pericytes In Vitro by Japanese Encephalitis Virus Disrupts the Integrity of the Endothelial Barrier

“…No apparent induction of metalloproteinase activity was detected in endothelial cells infected with JEV and exposed to JEV-conditioned medium. An elevated expression of metalloproteinase was demonstrated in rat astrocytes in response to JEV infection (42). That is, despite the crucial role of metalloproteinases in endothelial barrier integrity, their inductive expression varies and depends on cell types, stress, and microenviroments.…”