Dexamethasone inhibits the Nox-dependent ROS production via suppression of MKP-1-dependent MAPK pathways in activated microglia

<p>Abstract</p> <p>Background</p> <p>Nox-2 (also known as gp91<it>phox</it>), a subunit component of NADPH oxidases, generates reactive oxygen species (ROS). Nox-dependent ROS generation and nitric oxide (NO) release by microglia have been implicated in a variety of diseases in the central nervous system. Dexamethasone (Dex) has been shown to suppress the ROS production, NO release and inflammatory reaction of activated microglial cells. However, the underlying mechanisms remain unclear.</p> <p>Results</p> <p>The present study showed that the increased ROS production and NO release in activated BV-2 microglial cells by LPS were associated with increased expression of Nox-2 and iNOS. Dex suppressed the upregulation of Nox-2 and iNOS, as well as the subsequent ROS production and NO synthesis in activated BV-2 cells. This inhibition caused by Dex appeared to be mediated by upregulation of MAPK phosphatase-1 (MKP-1), which antagonizes the activity of mitogen-activated protein kinases (MAPKs). Dex induced-suppression of Nox-2 and -upregulation of MKP-1 was also evident in the activated microglia from corpus callosum of postnatal rat brains. The overexpression of MKP-1 or inhibition of MAPKs (by specific inhibitors of JNK and p38 MAPKs), were found to downregulate the expression of Nox-2 and iNOS and thereby inhibit the synthesis of ROS and NO in activated BV-2 cells. Moreover, Dex was unable to suppress the LPS-induced synthesis of ROS and NO in BV-2 cells transfected with MKP-1 siRNA. On the other hand, knockdown of Nox-2 in BV-2 cells suppressed the LPS-induced ROS production and NO release.</p> <p>Conclusion</p> <p>In conclusion, it is suggested that downregulation of Nox-2 and overexpression of MKP-1 that regulate ROS and NO may form the potential therapeutic strategy for the treatment of neuroinflammation in neurodegenerative diseases.</p

Scutellarin regulates microglia-mediated TNC1 astrocytic reaction and astrogliosis in cerebral ischemia in the adult rats

Additional file 1: (A). Scutellarin at 0.54 mM did not elicit a noticeable reaction of GFAP/iNOS in TNC1. (B). iNOS mRNA expression in TNC1 astrocytes remained relatively unchanged at all time-points following treatment with BM, BM + L and CM; however, when incubated with CM + L for various time points, TNC1 showed a remarkable increase in iNOS peaking at 24 h. (C). Confocal images showing iNOS (C1-3) expression in TNC1 astrocytes incubated with different medium for 24 h. Compared with cells incubated in BM (C1) and BM + L (C2), TNC1 astrocytes incubated with CM + L (C3) were hypertrophic and showed a marked increase in iNOS immunofluorescence. Scale bars: 20 μm. DAPI—blue

Expression of sphingosine kinase 1 in amoeboid microglial cells in the corpus callosum of postnatal rats

Sphingosine kinase 1 (SphK1), a key enzyme responsible for phosphorylating sphingosine into sphingosine-1-phosphate (S1P) has been shown to be expressed in monocytes and monocyte-derived peripheral macrophages. This study demonstrates SphK1 immunoexpression in amoeboid microglial cells (AMC), a nascent monocyte-derived brain macrophage in the corpus callosum of developing rat brain. SphK1 immunofluorescence expression, which appeared to be weak in AMC in normal brain, was markedly induced by lipopolysaccharide (LPS) or hypoxia treatment. Western blot analysis also showed increased expression level of SphK1 in the corpus callosum rich in AMC after LPS treatment. Detection of SphK1 mRNA and its upregulation after LPS treatment was confirmed in primary culture AMC by RT-PCR. Administration of N, N-dimethylsphingosine (DMS), a specific inhibitor of SphK1, effectively reduced upregulated SphK1 immunoexpression in AMC both in vivo and in vitro. This was corroborated by western blot which showed a decrease in SphK1 protein level of callosal tissue with DMS pretreatment. Remarkably, LPS-induced upregulation of the transcription factor NFκB was suppressed by DMS. We conclude that SphK1 expression in AMC may be linked to regulation of proinflammatory cytokines via an NFκB signaling pathway

Combination of Electroacupuncture and Grafted Mesenchymal Stem Cells Overexpressing TrkC Improves Remyelination and Function in Demyelinated Spinal Cord of Rats

10.1038/srep09133Scientific Reports

Expression of Notch-1 receptor and its ligands Jagged-1 and Delta-1 in amoeboid microglia in postnatal rat brain and murine BV-2 cells.

Notch-1 receptor signaling pathway is involved in neuronal and glial differentiation. Its involvement in microglial functions, however, has remained elusive. This study reports the localization of Notch-1 receptor immunoreactivity in the amoeboid microglial cells (AMC) in the postnatal rat brain. By immunofluorescence, Notch-1 receptor was colocalized with its ligands, Jagged-1 and Delta-1, in the AMC in the corpus callosum and subventricular zone. Notch-1 immunopositive cells were confirmed to be microglia labeled by OX42 and lectin. Immunoexpression of Notch-1 receptor was progressively reduced with age. Western blot analysis showed that Notch-1 protein level in the corpus callosum in which the AMC were heavily populated was concomitantly decreased. In postnatal rats challenged with lipopolysaccharide (LPS), Notch-1 receptor immunofluorescence in AMC was noticeably enhanced. Furthermore, Notch-1 protein level in the corpus callosum was increased as revealed by Western blotting analysis. In primary microglial culture treated with LPS, mRNA expression of Notch-1 and its ligand Jagged-1 was upregulated but that of Delta-1 was reduced. The expression pattern of Notch-1 and its ligands was confirmed in murine BV-2 cells. Furthermore, Notch-1 neutralization with its antibody reduced its protein expression. More importantly, neutralization of Notch-1 concomitantly suppressed the mRNA expression of IL-6, IL-1, M-CSF, and iNOS; TNF-α, mRNA expression, however, was enhanced. Western blot confirmed the changes of protein level of the above except for IL-6, which remained relatively unaltered. It is concluded that Notch-1 signaling in the AMC and LPS-activated microglia/BV-2 cells modulates the expression of proinflammatory cytokines and nitric oxide

High Origin of Radial Arteries: A Report of Two Rare Cases

Variations in the arterial supply of the upper limb are relatively common, with reported prevalence rates ranging from 11 to 24.4%. Of these, the most commonly encountered variation in the arm is a high origin of the radial artery. However, after consecutively dissecting and examining 600 Singaporean Chinese cadavers (1,200 upper limbs), we found only two cases of this. In both cases, the brachioradial artery originated from the upper one-third of the brachial artery and continued distally as the radial artery in the forearm. The local prevalence of 0.33% of this variation is significantly lower compared against populations from other geographical regions. Although rare, recognition of the variation is of fundamental importance to clinical practice

A modular assembly of spinal cord-like tissue allows targeted tissue repair in the transected spinal cord

Tissue engineering–based neural construction holds promise in providing organoids with defined differentiation and therapeutic potentials. Here, a bioengineered transplantable spinal cord–like tissue (SCLT) is assembled in vitro by simulating the white matter and gray matter composition of the spinal cord using neural stem cell–based tissue engineering technique. Whether the organoid would execute targeted repair in injured spinal cord is evaluated. The integrated SCLT, assembled by white matter–like tissue (WMLT) module and gray matter–like tissue (GMLT) module, shares architectural, phenotypic, and functional similarities to the adult rat spinal cord. Organotypic coculturing with the dorsal root ganglion or muscle cells shows that the SCLT embraces spinal cord organogenesis potentials to establish connections with the targets, respectively. Transplantation of the SCLT into the transected spinal cord results in a significant motor function recovery of the paralyzed hind limbs in rats. Additionally, targeted spinal cord tissue repair is achieved by the modular design of SCLT, as evidenced by an increased remyelination in the WMLT area and an enlarged innervation in the GMLT area. More importantly, the pro‐regeneration milieu facilitates the formation of a neuronal relay by the donor neurons, allowing the conduction of descending and ascending neural inputs