Anti-Inflammatory (M2) Response Is Induced by a sp2-Iminosugar Glycolipid Sulfoxide in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most common complications of Diabetes Mellitus (DM) and is directly associated with inflammatory processes. Currently, neuro-inflammation is considered an early event in DR and proceeds via microglia polarization. A hallmark of DR is the presence of retinal reactive gliosis. Here we report the beneficial effect of (SS,1R)-1-docecylsulfiny-5N,6O-oxomethylidenenojirimycin ((Ss)-DS-ONJ), a member of the sp2-iminosugar glycolipid (sp2-IGL) family, by decreasing iNOS and inflammasome activation in Bv.2 microglial cells exposed to pro-inflammatory stimuli. Moreover, pretreatment with (Ss)-DS-ONJ increased Heme-oxygenase (HO)-1 as well as interleukin 10 (IL10) expression in LPS-stimulated microglial cells, thereby promoting M2 (anti-inflammatory) response by the induction of Arginase-1. The results strongly suggest that this is the likely molecular mechanism involved in the anti-inflammatory effects of (SS)-DS-ONJ in microglia. (SS)-DS-ONJ further reduced gliosis in retinal explants from type 1 diabetic BB rats, which is consistent with the enhanced M2 response. In conclusion, targeting microglia polarization dynamics in M2 status by compounds with anti-inflammatory activities offers promising therapeutic interventions at early stages of DR.

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Differential Cytokine-Induced Responses of Polarized Microglia

Brain Sciences ◽

10.3390/brainsci11111482 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1482

Author(s):

Priyanka Chauhan ◽

Wen S. Sheng ◽

Shuxian Hu ◽

Sujata Prasad ◽

James R. Lokensgard

Keyword(s):

Inflammatory Cytokines ◽

Inflammatory Mediators ◽

Cell Polarization ◽

Microglial Cells ◽

Color Flow ◽

Arginase 1 ◽

Activated State ◽

Ifn Γ ◽

Anti Inflammatory ◽

Differential Responses

The role of select pro- and anti-inflammatory mediators in driving microglial cell polarization into classically (M1), or alternatively, (M2) activated states, as well as the subsequent differential responses of these induced phenotypes, was examined. Expression of PD-L1, MHC-II, MHC-I, arginase 1 (Arg-1), and inducible nitric oxide synthase (iNOS) was assessed using multi-color flow cytometry. We observed that both pro- and anti-inflammatory mediators induced PD-L1 expression on non-polarized microglia. Moreover, IFN-γ stimulated significant MHC class I and II expression on these cells. Interestingly, we observed that only IL-4 treatment induced Arg-1 expression, indicating M2 polarization. These M2 cells were refractory to subsequent depolarization and maintained their alternatively activated state. Furthermore, PD-L1 expression was significantly induced on these M2-polarized microglia after treatment with pro-inflammatory mediators, but not anti-inflammatory cytokines. In addition, we observed that only LPS induced iNOS expression in microglial cells, indicating M1 polarization. Furthermore, IFN-γ significantly increased the percentage of M1-polarized microglia expressing iNOS. Surprisingly, when these M1-polarized microglia were treated with either IL-6 or other anti-inflammatory cytokines, they returned to their non-polarized state, as demonstrated by significantly reduced expression of iNOS. Taken together, these results demonstrate differential responses of microglial cells to mediators present in dissimilar microenvironments.

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Anti-Inflammatory Strategy for M2 Microglial Polarization Using Retinoic Acid-Loaded Nanoparticles

Mediators of Inflammation ◽

10.1155/2017/6742427 ◽

2017 ◽

Vol 2017 ◽

pp. 1-11 ◽

Cited By ~ 14

Author(s):

Marta Machado-Pereira ◽

Tiago Santos ◽

Lino Ferreira ◽

Liliana Bernardino ◽

Raquel Ferreira

Keyword(s):

Nitric Oxide ◽

Retinoic Acid ◽

Inflammatory Diseases ◽

Polymeric Nanoparticles ◽

Microglial Cells ◽

Interleukin 4 ◽

Microglial Polarization ◽

Postsynaptic Protein ◽

Arginase 1 ◽

Anti Inflammatory

Inflammatory mechanisms triggered by microglial cells are involved in the pathophysiology of several brain disorders, hindering repair. Herein, we propose the use of retinoic acid-loaded polymeric nanoparticles (RA-NP) as a means to modulate microglia response towards an anti-inflammatory and neuroprotective phenotype (M2). RA-NP were first confirmed to be internalized by N9 microglial cells; nanoparticles did not affect cell survival at concentrations below 100 μg/mL. Then, immunocytochemical studies were performed to assess the expression of pro- and anti-inflammatory mediators. Our results show that RA-NP inhibited LPS-induced release of nitric oxide and the expression of inducible nitric oxide synthase and promoted arginase-1 and interleukin-4 production. Additionally, RA-NP induced a ramified microglia morphology (indicative of M2 state), promoting tissue viability, particularly neuronal survival, and restored the expression of postsynaptic protein-95 in organotypic hippocampal slice cultures exposed to an inflammatory challenge. RA-NP also proved to be more efficient than the free equivalent RA concentration. Altogether, our data indicate that RA-NP may be envisioned as a promising therapeutic agent for brain inflammatory diseases.

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Glycogen synthase kinase-3 negatively regulates anti-inflammatory interleukin-10 for lipopolysaccharide-induced iNOS/NO biosynthesis and RANTES production in microglial cells

Immunology ◽

10.1111/j.1365-2567.2008.02959.x ◽

2009 ◽

Vol 128 (1pt2) ◽

pp. e275-e286 ◽

Cited By ~ 81

Author(s):

Wei-Ching Huang ◽

Yee-Shin Lin ◽

Chi-Yun Wang ◽

Cheng-Chieh Tsai ◽

Hsiang-Chi Tseng ◽

...

Keyword(s):

Glycogen Synthase ◽

Interleukin 10 ◽

Microglial Cells ◽

Glycogen Synthase Kinase ◽

Glycogen Synthase Kinase 3 ◽

Anti Inflammatory ◽

Rantes Production

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Heparin inhibits proinflammatory and promotes anti-inflammatory macrophage polarization under hyperglycemic stress

Journal of Biological Chemistry ◽

10.1074/jbc.ra119.012419 ◽

2020 ◽

Vol 295 (15) ◽

pp. 4849-4857 ◽

Cited By ~ 1

Author(s):

Amina Abbadi ◽

Jacqueline Loftis ◽

Aimin Wang ◽

Minjia Yu ◽

Yan Wang ◽

...

Keyword(s):

Peripheral Blood ◽

Mesangial Cells ◽

Rat Kidney ◽

Macrophage Polarization ◽

Interleukin 10 ◽

Blood Monocytes ◽

Peripheral Blood Monocytes ◽

Murine Bone Marrow ◽

Arginase 1 ◽

Anti Inflammatory

Monocytes are rapidly recruited to sites of diabetic complications and differentiate into macrophages. Previously, we showed that rat kidney mesangial cells dividing during hyperglycemic stress abnormally synthesize hyaluronan (HA) in intracellular compartments. This initiates a stress response, resulting in an extracellular HA matrix after division that recruits inflammatory cells. Cell–cell communication among macrophages that are recruited into the glomeruli and the damaged rat mesangial cells leads to diabetic nephropathy, fibrosis, and proteinurea, which are inhibited in heparin-treated diabetic rats. In this study, we found that murine bone marrow–derived macrophages (BMDMs) and a human leukemic cell line, U937 cells, dividing in hyperglycemia also accumulate intracellular HA and that heparin inhibits the HA accumulation. Both cell types expressed increased levels of proinflammatory markers: inducible nitric-oxide synthase and tumor necrosis factor-α, when cultured under hyperglycemic stress, which was inhibited by heparin. Furthermore, the abnormal intracellular HA was also observed in peripheral blood monocytes derived from three different hyperglycemic diabetic mouse models: streptozotocin-treated, high-fat fed, and Ins2Akita. Moreover, peripheral blood monocytes in humans with type 2 diabetes and poorly controlled blood glucose levels (hemoglobin A1c (HbA1c) levels of >7) also had intracellular HA, whereas those with HbA1c of <7, did not. Of note, heparin increased the anti-inflammatory markers arginase 1 and interleukin-10 in murine BMDMs. We conclude that heparin treatment of high glucose–exposed dividing BMDMs promotes an anti-inflammatory tissue-repair phenotype in these cells.

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Diabetic Retinopathy and NADPH Oxidase-2: A Sweet Slippery Road

Antioxidants ◽

10.3390/antiox10050783 ◽

2021 ◽

Vol 10 (5) ◽

pp. 783

Author(s):

Renu A. Kowluru

Keyword(s):

Diabetic Retinopathy ◽

Nadph Oxidase ◽

Vision Loss ◽

Complex Structure ◽

Cell Loss ◽

Experimental Models ◽

Therapeutic Interventions ◽

Early Event ◽

Diabetic Patients ◽

Nadph Oxidase 2

Diabetic retinopathy remains the leading cause of vision loss in working-age adults. The multi-factorial nature of the disease, along with the complex structure of the retina, have hindered in elucidating the exact molecular mechanism(s) of this blinding disease. Oxidative stress appears to play a significant role in its development and experimental models have shown that an increase in cytosolic Reacttive Oxygen Speies (ROS) due to the activation of NADPH oxidase 2 (Nox2), is an early event, which damages the mitochondria, accelerating loss of capillary cells. One of the integral proteins in the assembly of Nox2 holoenzyme, Rac1, is also activated in diabetes, and due to epigenetic modifications its gene transcripts are upregulated. Moreover, addition of hyperlipidemia in a hyperglycemic milieu (type 2 diabetes) further exacerbates Rac1-Nox2-ROS activation, and with time, this accelerates and worsens the mitochondrial damage, ultimately leading to the accelerated capillary cell loss and the development of diabetic retinopathy. Nox2, a multicomponent enzyme, is a good candidate to target for therapeutic interventions, and the inhibitors of Nox2 and Rac1 (and its regulators) are in experimental or clinical trials for other diseases; their possible use to prevent/halt retinopathy will be a welcoming sign for diabetic patients.

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Gas6 Induces Myelination through Anti-Inflammatory IL-10 and TGF-β Upregulation in White Matter and Glia

Cells ◽

10.3390/cells9081779 ◽

2020 ◽

Vol 9 (8) ◽

pp. 1779

Author(s):

Salman Goudarzi ◽

Shannon E. Gilchrist ◽

Sassan Hafizi

Keyword(s):

Optic Nerve ◽

Glial Cell ◽

Transforming Growth Factor ◽

Transforming Growth Factor Β ◽

Interleukin 10 ◽

Therapeutic Interventions ◽

High Expression ◽

Receptor System ◽

Tam Receptors ◽

Anti Inflammatory

The Gas6–TAM (Tyro3, Axl, Mer) ligand–receptor system is believed to promote central nervous system (CNS) (re)myelination and glial cell development. An additional important function of Gas6–TAM signalling appears to be the regulation of immunity and inflammation, which remains to be fully elucidated in the CNS. Here, we characterised the expression of TAM receptors and ligands in individual CNS glial cell types, observing high expression of Gas6 and the TAM receptors, Mer and Axl, in microglia, and high expression of Tyro3 in astrocytes. We also investigated the effect of Gas6 on the inflammatory cytokine response in the optic nerve and in mixed glial cell cultures from wildtype and single TAM receptor knockout mice. In wildtype and Mer-deficient cultures, Gas6 significantly stimulated the expression of the anti-inflammatory/pro-repair cytokines interleukin 10 (IL-10) and transforming growth factor β (TGF-β), whereas this effect was absent in either Tyro3 or Axl knockout cultures. Furthermore, Gas6 caused upregulation of myelin basic protein (MBP) expression in optic nerves, which was blocked by a neutralising antibody against IL-10. In conclusion, our data show that microglia are both a major source of Gas6 as well as an effector of Gas6 action in the CNS through the upregulation of anti-inflammatory and pro-repair mediators. Furthermore, the presence of both Axl and Tyro3 receptors appears to be necessary for these effects of Gas6. In addition, IL-10, alongside suppressing inflammation and immunity, mediates the pro-myelinating mechanism of Gas6 action in the optic nerve. Therefore, Gas6 may present an attractive target for novel therapeutic interventions for demyelinating as well as neuroinflammatory disorders of the CNS.

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β-Funaltrexamine Displayed Anti-Inflammatory and Neuroprotective Effects in Cells and Rat Model of Stroke

International Journal of Molecular Sciences ◽

10.3390/ijms21113866 ◽

2020 ◽

Vol 21 (11) ◽

pp. 3866

Author(s):

Chih-Cheng Wu ◽

Cheng-Yi Chang ◽

Kuei-Chung Shih ◽

Chih-Jen Hung ◽

Ya-Yu Wang ◽

...

Keyword(s):

Neurodegenerative Diseases ◽

Rat Model ◽

Neuronal Degeneration ◽

Ischemia Reperfusion ◽

Sprague Dawley ◽

Neuroprotective Effects ◽

Arginase 1 ◽

Microglia Polarization ◽

Ifn Γ ◽

Anti Inflammatory

Chronic treatment involving opioids exacerbates both the risk and severity of ischemic stroke. We have provided experimental evidence showing the anti-inflammatory and neuroprotective effects of the μ opioid receptor antagonist β-funaltrexamine for neurodegenerative diseases in rat neuron/glia cultures and a rat model of cerebral Ischemia/Reperfusion (I/R) injury. Independent of in vitro Lipopolysaccharide (LPS)/interferon (IFN-γ)-stimulated neuron/glia cultures and in vivo cerebral I/R injury in Sprague–Dawley rats, β-funaltrexamine downregulated neuroinflammation and ameliorated neuronal degeneration. Alterations in microglia polarization favoring the classical activation state occurred in LPS/IFN-γ-stimulated neuron/glia cultures and cerebral I/R-injured cortical brains. β-funaltrexamine shifted the polarization of microglia towards the anti-inflammatory phenotype, as evidenced by decreased nitric oxide, tumor necrosis factor-α, interleukin-1β, and prostaglandin E2, along with increased CD163 and arginase 1. Mechanistic studies showed that the suppression of microglia pro-inflammatory polarization by β-funaltrexamine was accompanied by the reduction of NF-κB, AP-1, cyclic AMP response element-binding protein, along with signal transducers and activators of transcription transcriptional activities and associated upstream activators. The effects of β-funaltrexamine are closely linked with its action on neuroinflammation by switching microglia polarization from pro-inflammatory towards anti-inflammatory phenotypes. These findings provide new insights into the anti-inflammatory and neuroprotective mechanisms of β-funaltrexamine in combating neurodegenerative diseases, such as stroke.

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Through Reducing ROS Production, IL-10 Suppresses Caspase-1-Dependent IL-1β Maturation, thereby Preventing Chronic Neuroinflammation and Neurodegeneration

International Journal of Molecular Sciences ◽

10.3390/ijms21020465 ◽

2020 ◽

Vol 21 (2) ◽

pp. 465 ◽

Cited By ~ 4

Author(s):

Yun Gao ◽

Dezhen Tu ◽

Ru Yang ◽

Chun-Hsien Chu ◽

Jau-Shyong Hong ◽

...

Keyword(s):

Molecular Mechanisms ◽

Interleukin 10 ◽

Inflammasome Activation ◽

Dopaminergic Neurodegeneration ◽

Caspase 1 ◽

Chronic Neuroinflammation ◽

Nlrp3 Inflammasome Activation ◽

Anti Inflammatory

Chronic neuroinflammation contributes to the pathogenesis of Parkinson’s disease (PD). However, cellular and molecular mechanisms by which chronic neuroinflammation is formed and maintained remain elusive. This study aimed to explore detailed mechanisms by which anti-inflammatory cytokine interleukin-10 (IL-10) prevented chronic neuroinflammation and neurodegeneration. At 24 h after an intranigral injection of lipopolysaccharide (LPS), levels of NLRP3, pro-caspase-1, pro-IL-1β, active caspase-1, and mature IL-1β in the midbrain were much higher in IL-10−/− mice than wildtype mice. Mechanistically, IL-10−/− microglia produced more intracellular reactive oxygen species (iROS) and showed more profound activation of NADPH oxidase (NOX2) than wildtype microglia. Meanwhile, suppression of NOX2-derived iROS production blocked LPS-elicited caspase-1 activation and IL-1β maturation in IL-10−/− microglia in vitro and in vivo. One month after intranigral LPS injection, IL-10−/− mice revealed more profound microglial activation and dopaminergic neurodegeneration in the substantia nigra than wildtype mice. Importantly, such PD-like pathological changes were prevented by IL-1β neutralization. Collectively, IL-10 inhibited LPS-elicited production of NOX2-derived iROS thereby suppressing synthesis of NLRP3, pro-caspase-1 and pro-IL-1β and their activation and cleavage. By this mechanism, IL-10 prevented chronic neuroinflammation and neurodegeneration. This study suggested boosting anti-inflammatory effects of IL-10 and suppressing NLRP3 inflammasome activation could be beneficial for PD treatment.

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