Regulatory Effect of 25-hydroxyvitamin D₃ on Nitric Oxide Production in Activated Microglia

Jinyoung Hur,Pyeongjae Lee,Mi Jung Kim,Young-Wuk Cho 대한생리학회-대한약리학회 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.5

Microglia are activated by inflammatory and pathophysiological stimuli in neurodegenerative diseases, and activated microglia induce neuronal damage by releasing cytotoxic factors like nitric oxide (NO). Activated microglia synthesize a significant amount of vitamin D3 in the rat brain, and vitamin D₃ has an inhibitory effect on activated microglia. To investigate the possible role of vitamin D₃ as a negative regulator of activated microglia, we examined the effect of 25-hydroxyvitamin D₃ on NO production of lipopolysaccharide (LPS)-stimulated microglia. Treatment with LPS increased the production of NO in primary cultured and BV2 microglial cells. Treatment with 25-hydroxyvitamin D₃ inhibited the generation of NO in LPS-activated primary microglia and BV2 cells. In addition to NO production, expression of 1-α-hydroxylase and the vitamin D receptor (VDR) was also upregulated in LPS-stimulated primary and BV2 microglia. When BV2 cells were transfected with 1-α-hydroxylase siRNA or VDR siRNA, the inhibitory effect of 25-hydroxyvitamin D₃ on activated BV2 cells was suppressed. 25-Hydroxyvitamin D₃ also inhibited the increased phosphorylation of p38 seen in LPS-activated BV2 cells, and this inhibition was blocked by VDR siRNA. The present study shows that 25-hydroxyvitamin D₃ inhibits NO production in LPS-activated microglia through the mediation of LPS-induced 1-α-hydroxylase. This study also shows that the inhibitory effect of 25-hydroxyvitamin D₃ on NO production might be exerted by inhibiting LPS-induced phosphorylation of p38 through the mediation of VDR signaling. These results suggest that vitamin D3 might have an important role in the negative regulation of microglial activation.

Regulatory Effect of 25-hydroxyvitamin $D_3$ on Nitric Oxide Production in Activated Microglia

Hur, Jinyoung,Lee, Pyeongjae,Kim, Mi Jung,Cho, Young-Wuk The Korean Society of Pharmacology 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.5

Microglia are activated by inflammatory and pathophysiological stimuli in neurodegenerative diseases, and activated microglia induce neuronal damage by releasing cytotoxic factors like nitric oxide (NO). Activated microglia synthesize a significant amount of vitamin $D_3$ in the rat brain, and vitamin $D_3$ has an inhibitory effect on activated microglia. To investigate the possible role of vitamin $D_3$ as a negative regulator of activated microglia, we examined the effect of 25-hydroxyvitamin $D_3$ on NO production of lipopolysaccharide (LPS)-stimulated microglia. Treatment with LPS increased the production of NO in primary cultured and BV2 microglial cells. Treatment with 25-hydroxyvitamin $D_3$ inhibited the generation of NO in LPS-activated primary microglia and BV2 cells. In addition to NO production, expression of 1-${\alpha}$-hydroxylase and the vitamin D receptor (VDR) was also upregulated in LPS-stimulated primary and BV2 microglia. When BV2 cells were transfected with 1-${\alpha}$-hydroxylase siRNA or VDR siRNA, the inhibitory effect of 25-hydroxyvitamin $D_3$ on activated BV2 cells was suppressed. 25-Hydroxyvitamin $D_3$ also inhibited the increased phosphorylation of p38 seen in LPS-activated BV2 cells, and this inhibition was blocked by VDR siRNA. The present study shows that 25-hydroxyvitamin $D_3$ inhibits NO production in LPS-activated microglia through the mediation of LPS-induced 1-${\alpha}$-hydroxylase. This study also shows that the inhibitory effect of 25-hydroxyvitamin $D_3$ on NO production might be exerted by inhibiting LPS-induced phosphorylation of p38 through the mediation of VDR signaling. These results suggest that vitamin $D_3$ might have an important role in the negative regulation of microglial activation.

Regulatory Effect of 25-hydroxyvitamin D3 on Nitric Oxide Production in Activated Microglia

허진영,이평재,김미정,조영욱 대한약리학회 2014 The Korean Journal of Physiology & Pharmacology Vol.18 No.5

Microglia are activated by inflammatory and pathophysiological stimuli in neurodegenerativediseases, and activated microglia induce neuronal damage by releasing cytotoxic factors like nitric oxide(NO). Activated microglia synthesize a significant amount of vitamin D3 in the rat brain, and vitaminD3 has an inhibitory effect on activated microglia. To investigate the possible role of vitamin D3 asa negative regulator of activated microglia, we examined the effect of 25-hydroxyvitamin D3 on NOproduction of lipopolysaccharide (LPS)-stimulated microglia. Treatment with LPS increased the productionof NO in primary cultured and BV2 microglial cells. Treatment with 25-hydroxyvitamin D3inhibited the generation of NO in LPS-activated primary microglia and BV2 cells. In addition to NOproduction, expression of 1-α -hydroxylase and the vitamin D receptor (VDR) was also upregulatedin LPS-stimulated primary and BV2 microglia. When BV2 cells were transfected with 1-α-hydroxylasesiRNA or VDR siRNA, the inhibitory effect of 25-hydroxyvitamin D3 on activated BV2 cells was suppressed. 25-Hydroxyvitamin D3 also inhibited the increased phosphorylation of p38 seen in LPSactivatedBV2 cells, and this inhibition was blocked by VDR siRNA. The present study shows that25-hydroxyvitamin D3 inhibits NO production in LPS-activated microglia through the mediation ofLPS-induced 1-α -hydroxylase. This study also shows that the inhibitory effect of 25-hydroxyvitaminD3 on NO production might be exerted by inhibiting LPS-induced phosphorylation of p38 through themediation of VDR signaling. These results suggest that vitamin D3 might have an important role inthe negative regulation of microglial activation.

Thrombin-activated microglia contribute to death of dopaminergic neurons in rat mesencephalic cultures: Dual roles of mitogen-activated protein kinase signaling pathways

Lee, Da Yong,Oh, Young J.,Jin, Byung Kwan Wiley Subscription Services, Inc., A Wiley Company 2005 GLIA Vol.51 No.2

<P>This study evaluated the role of thrombin-activated microglia in the neurodegeneration of mesencephalic cultures. Immunocytochemical and biochemical evidence indicated that in co-cultures consisting of rat cortical microglia and mesencephalic neurons, thrombin led to nonselective loss of mesencephalic neurons. Accompanying neurodegeneration, microglial activation was obvious, evidenced by expression of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) and by increasing production of TNF-α and nitric oxide (NO). In mesencephalic neurons treated with conditioned media (CM) taken from thrombin-activated microglia, the number of dopaminergic neurons was significantly attenuated. The neurotoxicity of the CM was diminished when it was derived from microglia co-treated with thrombin and either an extracellular signal-regulated kinase 1/2 (ERK1/2) pathway inhibitor (PD98059) or a p38-mitogen-activated protein kinase (p38-MAPK) inhibitor (SB203580). Moreover, jun N-terminal kinase (JNK) and p38-MAPK were activated in mesencephalic neurons treated with CM of thrombin-activated microglia. Inhibition of JNK and p38-MAPK rescued the dopaminergic neurons. Collectively, these results indicate that thrombin-activated microglia induce neurodegeneration in cultured mesencephalic neurons and that the MAPKs actively participate in both microglial activation and neurodegeneration. The present data carefully suggest that microglial activation triggered by thrombin may be involved in the neuropathological processes of dopaminergic neuronal cell death that occur in Parkinson's disease. © 2005 Wiley-Liss, Inc.</P>

Pro-apoptotic activity of N-myc in activation-induced cell death of microglia

Jung, Dae Young,Lee, Heasuk,Suk, Kyoungho Blackwell Science Ltd 2005 Journal of Neurochemistry Vol.94 No.1

<P>Abstract</P><P>Brain microglial cells are thought to undergo apoptosis following the exposure to inflammatory stimuli such as lipopolysaccharide (LPS) and IFN&ggr;, which is considered as an autoregulatory mechanism to control their own activation state. Here, we report that N-myc constitutes a novel apoptotic pathway of LPS/IFN&ggr;-activated microglia. The expression of N-myc was synergistically enhanced by LPS and IFN&ggr; in microglia. Tetracycline-based conditional expression of N-myc sensitized microglia to nitric oxide (NO)-induced apoptosis. Knockdown of N-myc expression using small interfering RNA (siRNA) attenuated LPS/IFN&ggr;-induced microglial apoptosis. An increase in N-myc expression, however, did not affect microglial production of NO or TNF&agr;. The synergistic effect of LPS/IFN&ggr; on the microglial N-myc induction was mediated through Janus kinase (JAK)/STAT1 (signal transducer and activator of transcription 1) pathway. Taken together, LPS/IFN&ggr;-induced N-myc participated in the activation-induced cell death of microglia by sensitizing the cells to NO-induced apoptosis; however, N-myc did not influence the processes of inflammatory activation of microglia.</P>

Resveratrol Induces the Expression of Interleukin-10 and Brain-Derived Neurotrophic Factor in BV2 Microglia under Hypoxia

Song, Juhyun,Cheon, So Yeong,Jung, Wonsug,Lee, Won Taek,Lee, Jong Eun MDPI 2014 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.15 No.9

<P>Microglia are the resident macrophages of the central nervous system (CNS) and play an important role in neuronal recovery by scavenging damaged neurons. However, overactivation of microglia leads to neuronal death that is associated with CNS disorders. Therefore, regulation of microglial activation has been suggested to be an important target for treatment of CNS diseases. In the present study, we investigated the beneficial effect of resveratrol, a natural phenol with antioxidant effects, in the microglial cell line, BV2, in a model of hypoxia injury. Resveratrol suppressed the mRNA expression of the pro-inflammatory molecule, tumor necrosis factor-α, and promoted the mRNA expression of the anti-inflammatory molecule, interleukin-10, in BV2 microglia under hypoxic conditions. In addition, resveratrol inhibited the activation of the transcription factor, nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB), which is upstream in the control of inflammatory reactions in hypoxia-injured BV2 microglia. Moreover, resveratrol promoted the expression of brain-derived neurotrophic factor (BDNF) in BV2 microglia under hypoxic stress. Overall, resveratrol may promote the beneficial function of microglia in ischemic brain injury.</P>

Intracellular Signaling Mechanisms Involved in LPS-induced Microglial Activation

Pyo, Hankyoung,Joe, Eunhye 아주대학교 1996 아주의학 Vol.1 No.2

Microglia activated within the injured nervous system further aggravate injuries . To study intracellular signal mechanisms underlying microglial activation, we cultured microglila obtained from 1∼3-day-old rat brains and activated them with a bacterial endotoxin, 500 ng/㎖ of lipopolysaccharide (LPS) for 2 days. The activated microglia underwent morphological changes from small and round or ramified cell bodies to large and flat ones. The activated microglia induced nitric oxide synthase (iNOS), resulting in nitric oxide (NO) release. However, both the morphological changes and iNOS induction were completely blocked if either 30 uM genestein, a tyrosine kinase inhibitor or 1 uM Go, a protein kinase C inhibitor was added concomitantly with LPS. These results suggest that tyrosine kinase and protein kinase C are involved in LPS-induced microglial activation.

Exosomes derived from regulatory T cells attenuates MPP+-induced inflammatory response and oxidative stress in BV-2 cells by inhibiting the TLR4/NF-κB signaling

Liu Jun,Zhang Junqing,Ao Yuanyuan 대한독성 유전단백체 학회 2023 Molecular & cellular toxicology Vol.19 No.2

Background Parkinson’s disease (PD) is a common neurodegenerative disorder associated with microglia-mediated neuroinfl ammation in pathogenesis. Regulatory T cells (Treg cells) are involved in the regulation of microglia activation and neuroinfl ammation. However, it is yet to be established whether exosomes derived from Treg cells (Treg-Exos) possess protective eff ect against MPP + -induced infl ammation and oxidative stress in microglia. Objective In our study, we examined the function of Treg cells in the in vitro PD model. MTT assay was used to assess the viability of BV2 cells. ROS, MDA, and SOD activity were detected, and ELISA was performed to estimate the infl ammatory response and oxidative stress of BV-2 cells. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting were applied to detect the level changes of genes involved in the TLR4/NF-κB signaling pathway. Results The results showed that Treg-Exos improved the cell viability of MPP + -treated BV2 cells. MPP + -induced increase in ROS and MDA production, as well as decrease in SOD activity in BV2 cells were attenuated by Treg-Exos. The increased levels of infl ammatory cytokines IL-β, IL-6, and TNF-α in MPP + -induced BV2 cells were also prevented by the treatment of Treg-Exos. Treg-Exos inhibited MPP + -induced activation of the TLR4/NF-κB signaling, indicated by decreased protein level of TLR4 and p-p65/p65 ratio in BV2 cells. Further, we also found that upregulation of TLR4 blocks the protective eff ect of Treg-Exos on MPP + -treated BV2 cells. Conclusions Collectively, Treg-Exos attenuated MPP + -induced oxidative stress and infl ammatory injury in BV-2 cells by inhibiting the TLR4/NF-κB signaling.

Adiponectin Regulates the Polarization and Function of Microglia via PPAR-γ Signaling Under Amyloid β Toxicity

Song, Juhyun,Choi, Seong-Min,Kim, Byeong C. Frontiers Media S.A. 2017 Frontiers in cellular neuroscience Vol.11 No.-

<P>Alzheimer’s disease (AD), characterized by the abnormal accumulation of amyloid beta (Aβ), is gradually increasing globally. Given that AD is considered a neuroinflammatory disease, recent studies have focused on the cellular mechanisms in brain inflammatory conditions that underlie AD neuropathology. Microglia are macrophage cells in the central nervous system (CNS) that are activated in response to Aβ condition. The function of microglia contributes to the neuroinflammation in AD brain, suggesting that microglia regulate the production of inflammatory mediators and contribute to the regeneration of damaged tissues. Adiponectin, an adipokine derived from adipose tissue, has been known to regulate inflammation and control macrophages during oxidative stress conditions. In present study, we investigated whether adiponectin influences the polarization and function of microglia under Aβ toxicity by examining alterations of BV2 microglia function and polarization by Acrp30 (a globular form of adiponectin) treatment using reverse transcription PCR, western blotting and immunofluorescence staining. Acrp30 promoted the induction of the M2 phenotype, and regulated the inflammatory responses through peroxisome proliferator-activated receptor (PPAR)-γ signaling under Aβ toxicity. In addition, Acrp30 boosted the capacity of Aβ scavenging in microglia. Taken together, we suggest that adiponectin may control the function of microglia by promoting anti-inflammatory responses through PPAR- γ signaling. Hence, we conclude that adiponectin may act as a critical controller of microglia function in the AD brain.</P>

Oleanolic Acid Provides Neuroprotection against Ischemic Stroke through the Inhibition of Microglial Activation and NLRP3 Inflammasome Activation

( Arjun Sapkota ),( Ji Woong Choi ) 한국응용약물학회 2022 Biomolecules & Therapeutics(구 응용약물학회지) Vol.30 No.1

Oleanolic acid (OA), a natural pentacyclic triterpenoid, has been reported to exert protective effects against several neurological diseases through its anti-oxidative and anti-inflammatory activities. The goal of the present study was to evaluate the therapeutic potential of OA against acute and chronic brain injuries after ischemic stroke using a mouse model of transient middle cerebral artery occlusion (tMCAO, MCAO/reperfusion). OA administration immediately after reperfusion significantly attenuated acute brain injuries including brain infarction, functional neurological deficits, and neuronal apoptosis. Moreover, delayed administration of OA (at 3 h after reperfusion) attenuated brain infarction and improved functional neurological deficits during the acute phase. Such neuroprotective effects were associated with attenuation of microglial activation and lipid peroxidation in the injured brain after the tMCAO challenge. OA also attenuated NLRP3 inflammasome activation in activated microglia during the acute phase. In addition, daily administration of OA for 7 days starting from either immediately after reperfusion or 1 day after reperfusion significantly improved functional neurological deficits and attenuated brain tissue loss up to 21 days after the tMCAO challenge; these findings supported therapeutic effects of OA against ischemic stroke-induced chronic brain injury. Together, these findings showed that OA exerted neuroprotective effects against both acute and chronic brain injuries after tMCAO challenge, suggesting that OA is a potential therapeutic agent to treat ischemic stroke.