scholarly journals Candesartan modulates microglia activation and polarization via NF-κB signaling pathway

2020 ◽  
Vol 34 ◽  
pp. 205873842097490
Author(s):  
Shuyan Qie ◽  
Yuanyuan Ran ◽  
Xiaosheng Lu ◽  
Wei Su ◽  
Wei Li ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Protein Level ◽  
Type I ◽  
Dependent Manner ◽  
Neurotoxic Effect ◽  
Bv2 Cells ◽  
Microglia Polarization ◽  
Ifn Γ ◽  
Phenotype Markers ◽  
M2 Phenotype

Microglia are diverse cells that acquire different functional phenotypes in response to microenvironment in which they reside. Several transcriptional regulators have been identified that regulate different microglia phenotypes. They are mainly stimulated into two opposing phenotypes, classically (M1) and alternatively (M2) phenotype. Regulating microglia polarization from M1 to M2 state has been suggested as a potential therapeutic approach in treatment of CNS disorders. Candesartan, an angiotensin II type I receptors antagonist, exerts beneficial effects for antioxidant, anti-inflammation, neurotrophic, and anti-apoptotic function. However, the effect of candesartan on microglia polarization and underlying mechanisms remain unknown. In this study, the resting microglia were stimulated to M1 microglia with lipopolysaccharide (LPS) and interferon-γ (IFN-γ), and then treated with vehicle or candesartan for 24 h. RT-PCR was utilized to detect the mRNA expression of microglia phenotype markers and inflammatory cytokines. Microglia phenotype markers and toll-like receptor 4 (TLR4)/nuclear factor kappa B (NF-κB) pathway were determined by western blot. A neuron-microglia co-culture system was used to determine whether candesartan could ameliorate the neurotoxic effect of M1 microglia to oxygen-glucose deprivation (OGD) neuron. Candesartan treatment reduced the expression of M1 markers, and increased M2 markers. Meanwhile, candesartan reduced fluorescence intensity and protein level of M1 marker and enhanced M2 marker. Candesartan also regulated the neuroinflammatory response via reducing the release of pro-inflammatory cytokines and increasing anti-inflammatory cytokines in LPS + IFN-γ stimulated BV2 cells. Candesartan markedly inhibited the protein level of TLR4, the phosphorylation of IKBα and p65, and suppressed nuclear translocation of NF-κB p65. BAY 11-7085, a NF-κB inhibitor, remarkably enlarged the inhibitory effect of candesartan on NF-κB pathway. In addition, M1 phenotype microglia exacerbated post-OGD N2a cells death and LDH release, whereas candesartan reversed such neurotoxic effect. Candesartan treatment may ameliorate stroke-induced neuronal damage through shifting microglia to M2 phenotype in a TLR4/NF-κB-dependent manner.

scholarly journals UBQLN2 Promotes the Production of Type I Interferon via the TBK1-IRF3 Pathway

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1205
Author(s):  
Tianhong Chen ◽  
Wenjuan Zhang ◽  
Bo Huang ◽  
Xuan Chen ◽  
Cao Huang
Keyword(s):  
Inflammatory Cytokines ◽  
Type I Interferon ◽  
Complete Loss ◽  
Functional Assay ◽  
Type I ◽  
Dependent Manner ◽  
Frontotemporal Degeneration ◽  
Dose Dependent ◽  
Lateral Sclerosis ◽  
Pro Inflammatory Cytokines

Mutations of Ubiquilin 2 (UBQLN2) or TANK-binding kinase 1 (TBK1) are associated with amyotrophic lateral sclerosis and frontotemporal degeneration (ALS/FTD). However, the mechanisms whereby UBQLN2 or TBK1 mutations lead to ALS and FTD remain unclear. Here, we explored the effect of UBQLN2 on TBK1 in HEK-293T cells or in CRISPR–Cas9-mediated IRF3 and IRF7 knockout (KO) cells. We found an interaction between TBK1 and UBQLN2, which was affected by ALS/FTD-linked mutations in TBK1 or UBQLN2. Co-expression of UBQLN2 with TBK1 elevated the protein level of TBK1 as well as the phosphorylation of TBK1 and IRF3 in a UBQLN2 dose-dependent manner, and this phosphorylation was reduced by mutant UBQLN2. In addition, the cellular production of IFN1 and related pro-inflammatory cytokines was substantially elevated when UBQLN2 and TBK1 were co-expressed, which was also decreased by mutant UBQLN2. Functional assay revealed that mutant UBQLN2 significantly reduced the binding affinity of TBK1 for its partners, including IRF3, (SQSTM1)/p62 and optineurin (OPTN). Moreover, complete loss of IRF3 abolished the induction of IFN1 and related pro-inflammatory cytokines enhanced by UBQLN2 in HEK-293T cells, whereas no significant change in IRF7 knockout cells was observed. Thus, our findings suggest that UBQLN2 promotes IRF3 phosphorylation via TBK1, leading to enhanced IFN1 induction, and also imply that the dysregulated TBK1-IRF3 pathway may play a role in UBQLN2-related neurodegeneration.

scholarly journals Comparison of Concanavalin a-Induced Murine Autoimmune Hepatitis Models

2018 ◽  
Vol 46 (3) ◽  
pp. 1241-1251 ◽  
Author(s):  
Tinghong Ye ◽  
Tingting Wang ◽  
Xiaoxue Yang ◽  
Xiaoli Fan ◽  
Maoyao Wen ◽  
...  
Keyword(s):  
Autoimmune Hepatitis ◽  
Inflammatory Cytokines ◽  
Concanavalin A ◽  
Current Treatment ◽  
Human Condition ◽  
Type I ◽  
Therapeutic Approaches ◽  
Tnf Α ◽  
Ifn Γ ◽  
New Treatments

Background/Aims: Autoimmune hepatitis (AIH) is a chronic necroinflammatory disease of the liver whose pathogenic mechanisms have not yet been elucidated. Moreover, the current treatment used for the vast majority of AIH patients is largely dependent on immunosuppressant administration and liver transplantation. However, research on the pathogenesis of AIH and effective new treatments for AIH have been hampered by a lack of animal models that accurately reproduce the human condition. Methods: AIH models created by concanavalin A (ConA) injections at different times and doses. The levels of ALT, AST, LDH and inflammatory cytokines were examined at various times after 20 mg/kg ConA was administered by ELISA using commercially available kits. Moreover, liver pathological changes were observed by flow cytometry (FCM) and H&E staining. Results: Our experiments demonstrated that the levels of ALT, AST, LDH and several inflammatory cytokines, including TNF-α, IFN-γ, and IL-6, were higher in the 20 mg/kg 12 h ConA group than in the other groups. Importantly, the numbers of activated CD4+ and CD8+ T lymphocytes in the blood, spleen and liver were calculated. These results showed that ConA (20 mg/kg for 12 h)-induced hepatitis was similar to that in clinical AIH patients. Furthermore, we found that the number of MDSCs in the blood was significantly increased in the ConA (20 mg/kg for 12 h) group compared with controls. Our findings indicated that ConA (20 mg/kg for 12 h)-induced hepatitis could be used as an experimental murine model that mirrors most of the pathogenic properties of human type I AIH. Conclusion: This model [ConA (20 mg/kg for 12 h)] provides a valuable tool for studying AIH immunopathogenesis and rapidly assessing novel therapeutic approaches.

scholarly journals CpG Oligodeoxynucleotide Treatment Enhances Innate Resistance and Acquired Immunity to African Trypanosomes

2007 ◽  
Vol 75 (5) ◽  
pp. 2366-2373 ◽  
Author(s):  
Tajie H. Harris ◽  
John M. Mansfield ◽  
Donna M. Paulnock
Keyword(s):  
Parasite Burden ◽  
Type I ◽  
Dependent Manner ◽  
Cpg Odn ◽  
Relative Resistance ◽  
African Trypanosomes ◽  
Innate Resistance ◽  
Cpg Oligodeoxynucleotide ◽  
Developmental Life Cycle ◽  
Ifn Γ

ABSTRACTRelative resistance to African trypanosomiasis is based on the development of a type I cytokine response, which is partially dependent on innate immune responses generated through MyD88 and Toll-like receptor 9 (TLR9). Therefore, we asked whether enhancement of the immune response by artificial stimulation with CpG oligodeoxynucleotide (ODN), a TLR9 agonist, would result in enhanced protection against trypanosomes. In susceptible BALB/c mice, relative resistance to infection was significantly enhanced by CpG ODN treatment and was associated with decreased parasite burden, increased cytokine production, and elevated parasite-specific B- and T-cell responses. In relatively resistant C57BL/6 mice, survival was not enhanced but early parasitemia levels were reduced 100-fold and the majority of the parasites were nondividing, short stumpy (SS) forms. CpG ODN treatment of lymphocyte-deficient C57BL/6-scidand BALB/cByJ-scidmice also enhanced survival and reduced parasitemia, indicating that innate resistance to trypanosome infection can be enhanced. In C57BL/6-scidand BALB/cByJ-scidmice, the parasites were also predominantly SS forms during the outgrowth of parasitemia. However, the effect of CpG ODN treatment on parasite morphology was not as marked in gamma interferon (IFN-γ)-knockout mice, suggesting that downstream effects of IFN-γ production may play a discrete role in parasite cell differentiation. Overall, these studies provide the first evidence that enhancement of resistance to African trypanosomes can be induced in susceptible animals in a TLR9-dependent manner and that CpG ODN treatment may influence the developmental life cycle of the parasites.

scholarly journals MiR-200c-3p inhibits LPS-induced M1 polarization of BV2 cells by targeting RIP2

2022 ◽  
Author(s):  
Lei Zhao ◽  
Xiaosong Liu ◽  
Jiankai Yang ◽  
Xiaoliang Wang ◽  
Xiaomeng Liu ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Nuclear Translocation ◽  
Inflammatory Responses ◽  
Luciferase Reporter ◽  
Dependent Manner ◽  
M1 Polarization ◽  
Bv2 Cells ◽  
M1 Phenotype ◽  
Lps Treatment ◽  
Pro Inflammatory Cytokines

Abstract Background Microglia are important immune cells, which can be induced by lipopolysaccharide (LPS) into M1 phenotype that express pro-inflammatory cytokines. Some studies have shown that microRNAs play critical roles in microglial activation. Objective This study was designed to investigate the role of miR-200c-3p in regulating inflammatory responses of LPS-treated BV2 cells. Methods The expression of miR-200c-3p in BV2 cells was detected by real-time PCR. Receptor-interacting protein 2 (RIP2) was predicted as a target gene of miR-200c-3p. Their relationship was verified by dual-luciferase reporter assay. The function of miR-200c-3p and RIP2 in microglial polarization and NF-κB signaling was further evaluated. Results LPS treatment reduced miR-200c-3p expression in a dose-dependent and time-dependent manner in BV2 cells. LPS treatment increased the expression of M1 phenotype markers inducible nitric oxide synthase (iNOS) and major histocompatibility complex class (MHC)-II, promoted the release of pro-inflammatory cytokines interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, and enhanced the nuclear translocation and phosphorylation of nuclear factor-kappaB (NF-κB) p65. Reversely, miR-200c-3p mimics down-regulated the levels of these inflammatory factors. Furthermore, RIP2 was identified to be a direct target of miR-200c-3p. RIP2 knockdown had a similar effect to miR-200c-3p mimics. Overexpression of RIP2 eliminated the inhibitory effect of miR-200c-3p on LPS-induced M1 polarization and NF-κB activation in BV2 cells. Conclusions MiR-200c-3p mimics suppressed LPS-induced microglial M1 polarization and NF-κB activation by targeting RIP2. MiR-200c-3p/RIP2 might be a potential therapeutic target for the treatment of neuroinflammation-associated diseases.

scholarly journals IRGM3 Contributes to Immunopathology and Is Required for Differentiation of Antigen-Specific Effector CD8+T Cells in Experimental Cerebral Malaria

2015 ◽  
Vol 83 (4) ◽  
pp. 1406-1417 ◽  
Author(s):  
Jintao Guo ◽  
James A. McQuillan ◽  
Belinda Yau ◽  
Gregory S. Tullo ◽  
Carole A. Long ◽  
...  
Keyword(s):  
T Cells ◽  
Cerebral Malaria ◽  
Inflammatory Cytokines ◽  
Inflammatory Responses ◽  
Type I ◽  
Experimental Cerebral Malaria ◽  
Content Type ◽  
Cytokines And Chemokines ◽  
Specific Effector ◽  
Ifn Γ

Gamma interferon (IFN-γ) drives antiparasite responses and immunopathology during infection withPlasmodiumspecies. Immunity-related GTPases (IRGs) are a class of IFN-γ-dependent proteins that are essential for cell autonomous immunity to numerous intracellular pathogens. However, it is currently unknown whether IRGs modulate responses during malaria. We have used thePlasmodium bergheiANKA (PbA) model in which mice develop experimental cerebral malaria (ECM) to study the roles of IRGM1 and IRGM3 in immunopathology. Induction of mRNA forIrgm1andIrgm3was found in the brains and spleens of infected mice at times of peak IFN-γ production.Irgm3−/−but notIrgm1−/−mice were completely protected from the development of ECM, and this protection was associated with the decreased induction of inflammatory cytokines, as well as decreased recruitment and activation of CD8+T cells within the brain. Although antigen-specific proliferation of transferred CD8+T cells was not diminished compared to that of wild-type recipients following PbA infection, T cells transferred intoIrgm3−/−recipients showed a striking impairment of effector differentiation. Decreased induction of several inflammatory cytokines and chemokines (interleukin-6, CCL2, CCL3, and CCL4), as well as enhanced mRNA expression of type-I IFNs, was found in the spleens ofIrgm3−/−mice at day 4 postinfection. Together, these data suggest that protection from ECM pathology inIrgm3−/−mice occurs due to impaired generation of CD8+effector function. This defect is nonintrinsic to CD8+T cells. Instead, diminished T cell responses most likely result from defective initiation of inflammatory responses in myeloid cells.

scholarly journals Two Modes of the Axonal Interferon Response Limit Alphaherpesvirus Neuroinvasion

mBio ◽  
2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Ren Song ◽  
Orkide O. Koyuncu ◽  
Todd M. Greco ◽  
Benjamin A. Diner ◽  
Ileana M. Cristea ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Cell Body ◽  
Type I ◽  
Dependent Manner ◽  
Type Ii ◽  
Long Distance ◽  
Peripheral Tissues ◽  
Ifn Γ ◽  
Simplex Virus

ABSTRACT Infection by alphaherpesviruses, including herpes simplex virus (HSV) and pseudorabies virus (PRV), typically begins at epithelial surfaces and continues into the peripheral nervous system (PNS). Inflammatory responses are induced at the infected peripheral site prior to invasion of the PNS. When the peripheral tissue is first infected, only the innervating axons are exposed to this inflammatory milieu, which includes the interferons (IFNs). The fundamental question is how do PNS cell bodies respond to these distant, potentially damaging events experienced by axons. Using compartmented cultures that physically separate neuron axons from cell bodies, we found that pretreating isolated axons with beta interferon (IFN-β) or gamma interferon (IFN-γ) significantly diminished the number of herpes simplex virus 1 (HSV-1) and PRV particles moving in axons toward the cell bodies in a receptor-dependent manner. Exposing axons to IFN-β induced STAT1 phosphorylation (p-STAT1) only in axons, while exposure of axons to IFN-γ induced p-STAT1 accumulation in distant cell body nuclei. Blocking transcription in cell bodies eliminated antiviral effects induced by IFN-γ, but not those induced by IFN-β. Proteomic analysis of IFN-β- or IFN-γ-treated axons identified several differentially regulated proteins. Therefore, unlike treatment with IFN-γ, IFN-β induces a noncanonical, local antiviral response in axons. The activation of a local IFN response in axons represents a new paradigm for cytokine control of neuroinvasion. IMPORTANCE Neurons are highly polarized cells with long axonal processes that connect to distant targets. PNS axons that innervate peripheral tissues are exposed to various situations that follow infection, inflammation, and damage of the tissue. After viral infection in the periphery, axons represent potential front-line barriers to PNS infection and damage. Indeed, most viral infections do not spread to the PNS, yet the mechanisms responsible are not well studied. We devised an experimental system to study how axons respond to inflammatory cytokines that would be produced by infected tissues. We found that axons respond differentially to type I and type II interferons. The response to type I interferon (IFN-β) is a rapid axon-only response. The response to type II interferon (IFN-γ) involves long-distance signaling to the PNS cell body. These responses to two interferons erect an efficient and rapid barrier to PNS infection.

scholarly journals Keap1 regulates inflammatory signaling in Mycobacterium avium-infected human macrophages

2015 ◽  
Vol 112 (31) ◽  
pp. E4272-E4280 ◽  
Author(s):  
Jane Atesoh Awuh ◽  
Markus Haug ◽  
Jennifer Mildenberger ◽  
Anne Marstad ◽  
Chau Phuc Ngoc Do ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Mycobacterium Avium ◽  
Ubiquitin Ligase ◽  
Nuclear Translocation ◽  
Negative Regulator ◽  
Type I ◽  
Dependent Manner ◽  
Inflammatory Signaling ◽  
Human Macrophages ◽  
Ubiquitin Ligase Complex

Several mechanisms are involved in controlling intracellular survival of pathogenic mycobacteria in host macrophages, but how these mechanisms are regulated remains poorly understood. We report a role for Kelch-like ECH-associated protein 1 (Keap1), an oxidative stress sensor, in regulating inflammation induced by infection with Mycobacterium avium in human primary macrophages. By using confocal microscopy, we found that Keap1 associated with mycobacterial phagosomes in a time-dependent manner, whereas siRNA-mediated knockdown of Keap1 increased M. avium-induced expression of inflammatory cytokines and type I interferons (IFNs). We show evidence of a mechanism whereby Keap1, as part of an E3 ubiquitin ligase complex with Cul3 and Rbx1, facilitates ubiquitination and degradation of IκB kinase (IKK)-β thus terminating IKK activity. Keap1 knockdown led to increased nuclear translocation of transcription factors NF-κB, IFN regulatory factor (IRF) 1, and IRF5 driving the expression of inflammatory cytokines and IFN-β. Furthermore, knockdown of other members of the Cul3 ubiquitin ligase complex also led to increased cytokine expression, further implicating this ligase complex in the regulation of the IKK family. Finally, increased inflammatory responses in Keap1-silenced cells contributed to decreased intracellular growth of M. avium in primary human macrophages that was reconstituted with inhibitors of IKKβ or TANK-binding kinase 1 (TBK1). Taken together, we propose that Keap1 acts as a negative regulator for the control of inflammatory signaling in M. avium-infected human primary macrophages. Although this might be important to avoid sustained or overwhelming inflammation, our data suggest that a negative consequence could be facilitated growth of pathogens like M. avium inside macrophages.

scholarly journals Analgecine inhibits NF-kB to regulate microglia polarization by TLR4 MyD88-dependent and MyD88-independent pathways in ischemic stroke

2020 ◽  
Author(s):  
Cuicui Yang ◽  
Shili Gong ◽  
Xiaoping Chen ◽  
Mingyang Wang ◽  
Li Zhang ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Neuroprotective Effect ◽  
Neuronal Loss ◽  
Culture Systems ◽  
Microglial Polarization ◽  
Sd Rats ◽  
Microglia Polarization ◽  
Ifn Γ ◽  
Anti Inflammatory

Abstract Background: Microglia polarization plays an important role in poststroke recovery. Inhibition of proinflammatory (M1) polarization and promotion of anti-inflammatory (M2) polarization of microglia are potential therapeutic strategies for inflammation reduction and neuronal recovery after stroke. Analgecine (AGC), the extracts of Vaccin a variola-inoculated rabbit skin, is used to treat patients with chronic low back pain due to degenerative vertebral disorders. Here, we evaluated the neuroprotective effect of AGC in stroke and investigate anti-inflammatory mechanism of AGC on microglia-mediated neural damage.Methods: Sprague-Dawley (SD) rats underwent 120 min of middle cerebral artery occlusion (MCAO) followed by reperfusion. We injected AGC intravenously into rats starting 3 h after the onset of MCAO. Then we investigated the effect of AGC on neurological impairment, neuronal loss and inflammatory cytokines. For in vitro study, we examined the effect of AGC on microglial polarization in oxygen-glucose deprivation/reperfusion (OGD/R) or LPS/IFN-γ induced microglia cells and further investigated neuroprotective effect of ACG in microglia-mediated neural damage based on the direct or indirect co-culture systems. Finally, TLR4/Myd88/ NF-κB pathway was detected in OGD/R-induced microglia cells with or without Myd88 siRNA transfection.Results: AGC treatment reduced the neurological deficits and suppressed neuronal loss. In terms of inflammatory cytokines, AGC inhibited the release of pro-inflammatory cytokines and elevated the content of anti-inflammatory cytokines in vivo (SD rats) and in vitro (microglia). We further showed that AGC promoted M1 to M2 phenotypic transition of microglia in OGD/R or LPS/IFN-γ induced microglia cells. Based on the direct or indirect co-culture systems, we found AGC indirectly inhibits LPS/IFN-γ-induced neuronal damage by modulating microglial polarization. Moreover, AGC suppressed the nuclear translocation of the phosphorylation of NF-κB p65 by inhibiting the TLR4/Myd88/TRAF6 but not TLR9 signaling. We also confirmed that AGC-regulated TLR4 inhibition partly dependent on Myd88 in a Myd88 depletion cell line.Conclusion: Our findings provide a new understanding of AGC in neuroprotection by inhibiting M1 microglial polarization and promoting anti-inflammation by suppressing TLR4 MyD88-dependent and MyD88-independent pathways. Thus, AGC treatment may represent a novel approach in inflammation reduction or poststroke recovery.

scholarly journals The Non-structural Protein NSs of SFTSV Causes Cytokine Storm Through the Hyper-activation of NF-κB

2020 ◽  
Author(s):  
Jumana Khalil ◽  
Shintaro Yamada ◽  
Yuta Tsukamoto ◽  
Hiroto Abe ◽  
Masayuki Shimojima ◽  
...  
Keyword(s):  
Inflammatory Cytokines ◽  
Pharmacological Intervention ◽  
Type I ◽  
Dependent Manner ◽  
Cytokine Storm ◽  
Structural Protein ◽  
Cytokines And Chemokines ◽  
Activity Dependent

Severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV) is an emerging highly pathogenic phlebovirus. The syndrome is characterized by the substantial production of inflammatory cytokines and chemokines, described as cytokine storm, which correlates with multi-organ failure and high mortality. SFSTV nonstructural (NSs) protein was suggested to mediate the pathogenesis by inhibiting antiviral interferon signaling in the host. However, whether SFTSV NSs protein mediates the induction of fatal cytokine storm remains unaddressed. We demonstrated that SFTSV NSs promotes the hyper-induction of cytokine/chemokine genes in vitro, reminiscent of cytokine storm. Using gene deletion and pharmacological intervention, we found that the induced cytokine storm is driven by the transcription factor NF-κB. Our investigation revealed that TANK-binding kinase 1 (TBK1) suppresses NF-κB signaling and cytokine/chemokine induction in its kinase activity-dependent manner, and that NSs sequesters TBK1 to prevent it from suppressing NF-κB, thereby promoting the activation of NF-κB and its target cytokine/chemokine genes. Of note, NF-κB inhibition suppressed the induction of pro-inflammatory cytokines in SFTSV-infected type I interferon (IFN-I) receptor 1-deficient (Ifnar1-/-) mice. These findings establish the essential role of NSs in SFTS pathogenesis and suggest NF-κB as a possible therapeutic target.

scholarly journals Sestrin2 regulates microglia polarization through mTOR-mediated autophagic flux to attenuate inflammation during experimental brain ischemia

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Tingting He ◽  
Wanlu Li ◽  
Yaying Song ◽  
Zongwei Li ◽  
Yaohui Tang ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Western Blotting ◽  
Cell Apoptosis ◽  
Underlying Mechanism ◽  
Autophagic Flux ◽  
Mtor Signaling Pathway ◽  
Bv2 Cells ◽  
Microglia Polarization ◽  
Anti Inflammatory ◽  
M2 Phenotype

Abstract Background Neuroinflammation is the major pathogenesis of cerebral ischemia. Microglia are activated and polarized to either the pro-inflammatory M1 phenotype or anti-inflammatory M2 phenotype, which act as a critical mediator of neuroinflammation. Sestrin2 has pro-survival properties against ischemic brain injury. However, whether sestrin2 has an anti-inflammatory function by shifting microglia polarization and its underlying mechanism is unknown. Methods Adult male C57BL/6 mice (N = 108) underwent transient middle cerebral artery occlusion (tMCAO) and were treated with exogenous sestrin2. Neurological deficit scores and infarct volume were determined. Cell apoptosis was examined by TUNEL staining and Western blotting. The expression of inflammatory mediators, M1/M2-specific markers, and signaling pathways were detected by reverse transcription-polymerase chain reaction, immunostaining, and Western blotting. To explore the underlying mechanism, primary neurons were subjected to oxygen-glucose deprivation (OGD) and then treated with oxygenated condition medium of BV2 cells incubated with different doses of sestrin2. Results Sestrin2 attenuated the neurological deficits, infarction volume, and cell apoptosis after tMCAO compared to those in the control (p < 0.05). Sestrin2 had an anti-inflammatory effect and could suppress M1 microglia polarization and promote M2 microglia polarization. Condition medium from BV2 cells cultured with sestrin2 reduced neuronal apoptosis after OGD in vitro. Furthermore, we demonstrated that sestrin2 drives microglia to the M2 phenotype by inhibiting the mammalian target of rapamycin (mTOR) signaling pathway and restoring autophagic flux. Conclusions Sestrin2 exhibited neuroprotection by shifting microglia polarization from the M1 to M2 phenotype in ischemic mouse brain, which may be due to suppression of the mTOR signaling pathway and the restoration of autophagic flux.

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