Yazar "Huttner, Hagen B." seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim
    Öğe
    Knockdown of NEAT1 prevents post-stroke lipid droplet agglomeration in microglia by regulating autophagy
    (Springer Science and Business Media Deutschland GmbH, 2024) Pan, Yongli; Xin, Wenqiang; Wei, Wei; Tatenhorst, Lars; Graf, Irina; Popa-Wagner, Aurel; Gerner, Stefan T.; Huber, Sabine E.; Kılıç, Ertuğrul; Hermann, Dirk M.; Bähr, Mathias; Huttner, Hagen B.; Doeppner, Thorsten Roland
    Background: Lipid droplets (LD), lipid-storing organelles containing neutral lipids like glycerolipids and cholesterol, are increasingly accepted as hallmarks of inflammation. The nuclear paraspeckle assembly transcript 1 (NEAT1), a long non-coding RNA with over 200 nucleotides, exerts an indispensable impact on regulating both LD agglomeration and autophagy in multiple neurological disorders. However, knowledge as to how NEAT1 modulates the formation of LD and associated signaling pathways is limited. Methods: In this study, primary microglia were isolated from newborn mice and exposed to oxygen-glucose-deprivation/reoxygenation (OGD/R). To further explore NEAT1-dependent mechanisms, an antisense oligonucleotide (ASO) was adopted to silence NEAT1 under in vitro conditions. Studying NEAT1-dependent interactions with regard to autophagy and LD agglomeration under hypoxic conditions, the inhibitor and activator of autophagy 3-methyladenine (3-MA) and rapamycin (RAPA) were used, respectively. In a preclinical stroke model, mice received intraventricular injections of ASO NEAT1 or control vectors in order to yield NEAT1 knockdown. Analysis of readout parameters included qRT-PCR, immunofluorescence, western blot assays, and behavioral tests. Results: Microglia exposed to OGD/R displayed a temporal pattern of NEAT1 expression, peaking at four hours of hypoxia followed by six hours of reoxygenation. After effectively silencing NEAT1, LD formation and autophagy-related proteins were significantly repressed in hypoxic microglia. Stimulating autophagy in ASO NEAT1 microglia under OGD/R conditions by means of RAPA reversed the downregulation of LD agglomeration and perilipin 2 (PLIN2) expression. On the contrary, application of 3-MA promoted repression of both LD agglomeration and expression of the LD-associated protein PLIN2. Under in vivo conditions, NEAT1 was significantly increased in mice at 24 h post-stroke. Knockdown of NEAT1 significantly alleviated LD agglomeration and inhibited autophagy, resulting in improved cerebral perfusion, reduced brain injury and increased neurological recovery. Conclusion: NEAT1 is a key player of LD agglomeration and autophagy stimulation, and NEAT1 knockdown provides a promising therapeutic value against stroke. Graphical abstract: [Figure not available: see fulltext.].
  • Küçük Resim
    Öğe
    Preconditioned extracellular vesicles from hypoxic microglia reduce poststroke AQP4 depolarization, disturbed cerebrospinal fluid flow, astrogliosis, and neuroinflammation
    (NLM (Medline), 2023) Xin, Wenqiang; Pan, Yongli; Wei, Wei; Tatenhorst, Lars; Graf, Irina; Popa-Wagner, Aurel; Gerner, Stefan T.; Huber, Sabine; Kılıç, Ertuğrul; Hermann, Dirk M.; Bähr, Mathias; Huttner, Hagen B.; Doeppner, Thorsten Roland
    Background: Stroke stimulates reactive astrogliosis, aquaporin 4 (AQP4) depolarization and neuroinflammation. Preconditioned extracellular vesicles (EVs) from microglia exposed to hypoxia, in turn, reduce poststroke brain injury. Nevertheless, the underlying mechanisms of such effects are elusive, especially with regards to inflammation, AQP4 polarization, and cerebrospinal fluid (CSF) flow. Methods: Primary microglia and astrocytes were exposed to oxygen-glucose deprivation (OGD) injury. For analyzing the role of AQP4 expression patterns under hypoxic conditions, a co-culture model of astrocytes and microglia was established. Further studies applied a stroke model, where some mice also received an intracisternal tracer infusion of rhodamine B. As such, these in vivo studies involved the analysis of AQP4 polarization, CSF flow, astrogliosis, and neuroinflammation as well as ischemia-induced brain injury. Results: Preconditioned EVs decreased periinfarct AQP4 depolarization, brain edema, astrogliosis, and inflammation in stroke mice. Likewise, EVs promoted postischemic CSF flow and cerebral blood perfusion, and neurological recovery. Under in vitro conditions, hypoxia stimulated M2 microglia polarization, whereas EVs augmented M2 microglia polarization and repressed M1 microglia polarization even further. In line with this, astrocytes displayed upregulated AQP4 clustering and proinflammatory cytokine levels when exposed to OGD, which was reversed by preconditioned EVs. Reduced AQP4 depolarization due to EVs, however, was not a consequence of unspecific inflammatory regulation, since LPS-induced inflammation in co-culture models of astrocytes and microglia did not result in altered AQP4 expression patterns in astrocytes. Conclusions: These findings show that hypoxic microglia may participate in protecting against stroke-induced brain damage by regulating poststroke inflammation, astrogliosis, AQP4 depolarization, and CSF flow due to EV release.
  • Küçük Resim
    Öğe
    Preconditioning concepts for the therapeutic use of extracellular vesicles against stroke
    (Oxford University Press, 2023) Haupt, Matteo; Gerner, Stefan T.; Huttner, Hagen B.; Doeppner, Thorsten Roland
    Various preclinical stroke models have demonstrated the neuroprotective effects of extracellular vesicles (EVs) obtained from several types of cells, including neurons, astrocytes, microglia, neuronal progenitor cells, bone marrow stem cells, and mesenchymal stem cells. EVs interfere with key mechanisms in stroke pathophysiology such as cell death, neuroinflammation, autophagy, and angiogenesis. The mode of action and efficacy depend on the specific EV content, including miRNAs, proteins, and lipids, which can be modified through (I) bioengineering methods, (II) choice of source cells, and (III) modification of the source cell environment. Indeed, modifying the environment by preconditioning the EV-secreting cells with oxygen-glucose deprivation or medium modification revealed superior neuroprotective effects in stroke models. Although the concept of preconditioned EVs is relatively novel, it holds promise for the future treatment of ischemic stroke. Here, we give a brief overview about the main mechanisms of EV-induced neuroprotection and discuss the current status of preconditioning concepts for EV-treatment of ischemic stroke.
  • Küçük Resim
    Öğe
    TGF-?1 decreases microglia-mediated neuroinflammation and lipid droplet accumulation in an in vitro stroke model
    (Multidisciplinary Digital Publishing Institute (MDPI), 2023) Xin, Wenqiang; Pan, Yongli; Wei, Wei; Gerner, Stefan T.; Huber, Sabine; Juenemann, Martin; Butz, Marius; Baehr, Mathias; Huttner, Hagen B.; Doeppner, Thorsten Roland
    Hypoxia triggers reactive microglial inflammation and lipid droplet (LD) accumulation under stroke conditions, although the mutual interactions between these two processes are insufficiently understood. Hence, the involvement of transforming growth factor (TGF)-beta 1 in inflammation and LD accumulation in cultured microglia exposed to hypoxia were analyzed herein. Primary microglia were exposed to oxygen-glucose deprivation (OGD) injury and lipopolysaccharide (LPS) stimulation. For analyzing the role of TGF-beta 1 patterns under such conditions, a TGF-beta 1 siRNA and an exogenous recombinant TGF-beta 1 protein were employed. Further studies applied Triacsin C, an inhibitor of LD formation, in order to directly assess the impact of LD formation on the modulation of inflammation. To assess mutual microglia-to-neuron interactions, a co-culture model of these cells was established. Upon OGD exposure, microglial TGF-beta 1 levels were significantly increased, whereas LPS stimulation yielded decreased levels. Elevating TGF-beta 1 expression proved highly effective in suppressing inflammation and reducing LD accumulation in microglia exposed to LPS. Conversely, inhibition of TGF-beta 1 led to the promotion of microglial cell inflammation and an increase in LD accumulation in microglia exposed to OGD. Employing the LD formation inhibitor Triacsin C, in turn, polarized microglia towards an anti-inflammatory phenotype. Such modulation of both microglial TGF-beta 1 and LD levels significantly affected the resistance of co-cultured neurons. This study provides novel insights by demonstrating that TGF-beta 1 plays a protective role against microglia-mediated neuroinflammation through the suppression of LD accumulation. These findings offer a fresh perspective on stroke treatment, suggesting the potential of targeting this pathway for therapeutic interventions.