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Stroke is a major cause of serious disability due to the brain’s limited capacity to regenerate damaged tissue and neuronal circuits. After ischemic injury, a multiphasic degenerative and inflammatory response is coupled with severely restricted vascular and neuronal repair, resulting in permanent functional deficits. Although clinical evidence indicates that revascularization of the ischemic brain regions is crucial for functional recovery, no therapeutics that promote angiogenesis after cerebral stroke are currently available. Besides vascular growth factors, guidance molecules have been identified to regulate aspects of angiogenesis in the central nervous system (CNS) and may provide targets for therapeutic angiogenesis. In this study, we demonstrate that genetic deletion of the neurite outgrowth inhibitor Nogo-A or one of its corresponding receptors, S1PR2, improves vascular sprouting and repair and reduces neurological deficits after cerebral ischemia in mice. These findings were reproduced in a therapeutic approach using intrathecal anti–Nogo-A antibodies; such a therapy is currently in clinical testing for spinal cord injury. These results provide a basis for a therapeutic blockage of inhibitory guidance molecules to improve vascular and neural repair after ischemic CNS injuries.

Pyroptosis is an identified programmed cell death that has been highly linked to endoplasmic reticulum (ER) dynamics. However, the crucial proteins for modulating dynamic ER membrane curvature change that trigger pyroptosis are currently not well understood. In this study, a biotin-labeled chemical probe of potent pyroptosis inducer α-mangostin (α-MG) was synthesized. Through protein microarray analysis, reticulon-4 (RTN4/Nogo), a crucial regulator of ER membrane curvature, was identified as a target of α-MG. We observed that chemically induced proteasome degradation of RTN4 by α-MG through recruiting E3 ligase UBR5 significantly enhances the pyroptosis phenotype in cancer cells. Interestingly, the downregulation of RTN4 expression significantly facilitated a dynamic remodeling of ER membrane curvature through a transition from tubules to sheets, consequently leading to rapid fusion of the ER with the cell plasma membrane. In particular, the ER-to-plasma membrane fusion process is supported by the observed translocation of several crucial ER markers to the \"bubble\" structures of pyroptotic cells. Furthermore, α-MG-induced RTN4 knockdown leads to pyruvate kinase M2 (PKM2)-dependent conventional caspase-3/gasdermin E (GSDME) cleavages for pyroptosis progression. In vivo, we observed that chemical or genetic RTN4 knock-down significantly inhibited cancer cells growth, which further exhibited an antitumor immune response with anti-programmed death-1 (anti-PD-1). In translational research, RTN4 high expression was closely correlated with the tumor metastasis and death of patients. Taken together, RTN4 plays a fundamental role in inducing pyroptosis through the modulation of ER membrane curvature remodeling, thus representing a prospective druggable target for anticancer immunotherapy.

NG101 is a recombinant antibody that neutralizes the nerve growth inhibitor Nogo-A, promoting neural repair and improving upper extremity motor function in spinal cord injury (SCI). This study evaluated spinal cord MRI biomarkers to detect treatment-related structural changes and enhance patient stratification using data from 106 participants with acute cervical SCI in the phase 2b NISCI trial. We assessed lesion volume, tissue bridges, and remote changes in cross-sectional cord area (CSA), and tract-specific myelin-sensitive magnetization transfer saturation (MTsat) over six months. Compared to placebo, NG101-treated participants exhibited faster lesion volume reduction and a slower decline of CSA and MTsat in the corticospinal tracts and dorsal columns. Crucially, multimodal stratification incorporating MRI and electrophysiological measures substantially enhanced the detection of clinical treatment effects. These findings suggest NG101 slows trauma-induced progressive macro- and microstructural degeneration or promotes fiber sprouting. Combining MRI with electrophysiology enables sensitive detection of treatment effects and efficient trial designs. ClinicalTrials.gov identifier: NCT03935321. NG101 treatment for acute cervical spinal cord injury mitigates structural degeneration compared to placebo. Stratifying patients via MRI and electrophysiology identifies clinical responder subgroups, optimizing future trial designs.

Osteosarcoma (OS) has been defined as one of the most intricate and formidable malignant bone tumors, and there has been no significant improvement in targeted therapies for OS over the past 50 years. Therefore, it is crucial to identify new potential drug targets for OS. Here, we have developed a label-free activity-based protein profiling (ABPP) using a stereochemically selective probe from an in-house patrimonial library of covalent small molecule compounds to identify an anti-OS target. Phenotypic screening resulted in the discovery of a selective inhibitor ( S , R )- 4v that potently suppresses the proliferation of OS 143B cells with an IC 50 value of 0.28 µM. Subsequent label-free ABPP studies identified neurite outgrowth inhibitor B (Nogo-B) as the primary cellular target for ( S , R )- 4v via a rapid relatively quantitative analysis using its inactive isomer as control. This finding was validated by interaction assays including pull-down, cellular thermal shift assay (CETSA), molecular docking and functional studies. Mechanistic investigations revealed that the apoptotic effect induced by ( S , R )- 4v was mediated through Nogo-B inhibition of the PI3K/AKT-dependent NF-κB pathway. Altogether, this study presents a novel strategy that couples anti-OS compound screening with target identification and successfully identifies Nogo-B as a potential candidate for targeted OS therapy.

The aim of this study was to evaluate the neuroprotective effect of tanshinone IIA (TSA) on focal cerebral ischemia in rats and to investigate whether it was associated with Nogo-A/NgR1/RhoA/Rho-associated protein kinase 2 (ROCKII)/myosin light chain (MLC) signaling. In this study, focal cerebral ischemia animal model was used. Neurological deficit scores and infarction volume were investigated to evaluate the neuroprotection of TSA. Hematoxylin-eosin staining, Nissl staining, and immunofluorescence staining were conducted to detect ischemic changes in brain tissue and changes in neurofilament protein 200 (NF200) and growth-associated protein-43 (GAP-43) expression, respectively. Western blotting and qRT-PCR analyses were used to detect the expression levels of NF200, GAP-43 and Nogo-A/NgR1/RhoA/ROCKII/MLC pathway-related signaling molecules. TSA treatment can improve the survival rate of rats, reduce the neurological score and infarct volume, and reduce neuron damage. In addition, TSA also increased axon length and enhanced expression of NF200 and GAP-43. Importantly, TSA significantly attenuated the expression of Nogo-A, NgR1, RhoA, ROCKII, and p-MLC, and thus inhibiting the activation of this signaling pathway. TSA promoted axonal regeneration by inhibiting the Nogo-A/NgR1/RhoA/ROCKII/MLC signaling pathway, thereby exerting neuroprotective effects in cerebral ischemia rats, which provided support for the clinical application of TSA in stroke treatment.

Antibody-based therapeutics targeting CNS antigens emerge as promising treatments in neurology. However, access to the CNS is limited by the blood–brain barrier. We examined the effects of a neurite growth-enhancing anti-Nogo A antibody therapy following 3 routes of administration—intrathecal (i.t.), intravenous (i.v.), and subcutaneous (s.c.)—after large photothrombotic strokes in adult rats. Intrathecal treatment of full-length IgG anti-Nogo A antibodies enhanced recovery of the grasping function, but intravenous or subcutaneous administration had no detectable effect in spite of large amounts of antibodies in the peripheral circulation. Thus, in contrast to intravenous and subcutaneous delivery, intrathecal administration is an effective and reliable way to target CNS antigens. Our data reveal that antibody delivery to the CNS is far from trivial. While intrathecal application is feasible and guarantees defined antibody doses in the effective range for a biological function, the identification and establishment of easier routes of administration remains an important task to facilitate antibody-based future therapies of CNS disorders.

N-Methyl-D-aspartate (NMDA)-induced neuronal cell death is involved in a large spectrum of diseases affecting the brain and the retina such as Alzheimer’s disease and diabetic retinopathy. Associated neurological impairments may result from the inhibition of neuronal plasticity by Nogo-A. The objective of the current study was to determine the contribution of Nogo-A to NMDA excitotoxicity in the mouse retina. We observed that Nogo-A is upregulated in the mouse vitreous during NMDA-induced inflammation. Intraocular injection of a function-blocking antibody specific to Nogo-A (11C7) was carried out 2 days after NMDA-induced injury. This treatment significantly enhanced visual function recovery in injured animals. Strikingly, the expression of potent pro-inflammatory molecules was downregulated by 11C7, among which TNFα was the most durably decreased cytokine in microglia/macrophages. Additional analyses suggest that TNFα downregulation may stem from cofilin inactivation in microglia/macrophages. 11C7 also limited gliosis presumably via P.Stat3 downregulation. Diabetic retinopathy was associated with increased levels of Nogo-A in the eyes of donors. In summary, our results reveal that Nogo-A-targeting antibody can stimulate visual recovery after retinal injury and that Nogo-A is a potent modulator of excitotoxicity-induced neuroinflammation. These data may be used to design treatments against inflammatory eye diseases.

Myelin-associated inhibitors, such as NogoA, myelin-associated glycoprotein (MAG), and oligodendrocyte myelin glycoprotein (OMgp), play a pivotal role in the lack of neuroregeneration in multiple sclerosis, an inflammatory demyelinating disease of the central nervous system (CNS). Matrine (MAT), a monomer that is used in traditional Chinese medicine as an anti-inflammatory agent, has shown beneficial effects in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. However, the underlying mechanisms of MAT-induced EAE amelioration are not fully understood. In the present study, we show that MAT treatment suppressed ongoing EAE, and this effect correlated with an increased expression of growth-associated protein 43, an established marker for axonal regeneration. MAT treatment significantly reduced the levels of NogoA, its receptor complex NgR/p75NTR/LINGO-1, and their downstream RhoA/ROCK signaling pathway in the CNS. In contrast, intracellular cyclic AMP (cAMP) levels and its protein kinase (protein kinase A (PKA)), which can promote axonal regrowth by inactivating the RhoA, were upregulated. Importantly, adding MAT in primary astrocytes in vitro largely induced cAMP/PKA expression, and blockade of cAMP significantly diminished MAT-induced expression of PKA and production of BDNF, a potent neurotrophic factor for neuroregeneration. Taken together, our findings demonstrate that the beneficial effects of MAT on EAE can be attributed not only to its capacity for immunomodulation, but also to its directly promoting regeneration of the injured CNS.

Background/Aims: Nogo-B, a member of the reticulon family of proteins, is mainly located in the endoplasmic reticulum (ER). Here, we investigate the function and mechanism of Nogo-B in the regulation of TLR4-associated immune responses in the macrophage cell line of RAW264.7. Methods: Nogo-B was up- and down-regulated through the use of appropriate adenoviral vectors or siRNA, and the effects of Nogo-B on macrophages under liposaccharide (LPS) stimulation were evaluated via western blotting, immunofluorescence, enzyme-linked immunosorbent assay (ELISA), flow cytometric analysis, and transwell assay. Results: Our data indicates that the protein of Nogo-B was down-regulated in a time- and dose-dependent manner following LPS administration in the macrophage. Nogo-B overexpression increased the production of inflammatory cytokines (MCP-1, TNF-α, IL-1β, and TGF-β), enhanced macrophage migration activities, activated major histocompatibility complex II (MHC II), and elevated the expression of macrophage scavenger receptor 1(MSR1), all of which suggest that Nogo-B is necessary for immune responses and plays an important role in regulating macrophage recruitment. Mechanistically, Nogo-B may enhance TLR4 expression in macrophage surfaces, activate mitogen-activated protein kinase (MAPK) pathways, and initiate inflammatory responses. Conclusion: These findings illustrate the key regulatory functions of Nogo-B in facilitating LPS-mediated immune responses through promoting the phosphorylation of MAP kinase.

Background Alzheimer’s disease (AD) is characterized by extracellular β-amyloid (Aβ) plaques, neurofibrillary tangles (NFTs), and microglia-dominated neuroinflammation. The Nogo/NgR signal pathway is involved in AD pathological features, but the detailed mechanism needs further investigation. Our previous studies have confirmed that the activation of NgR on microglia by Nogo promotes the expression of proinflammatory cytokines and inhibits cell adhesion and migration behaviors. In the present study, we investigated the effects of Nogo/NgR signaling pathway on the pathological features of AD and possible mechanisms. Methods After NEP1-40 (a competitive antagonist of Nogo/NgR pathway) was intracerebroventricularly administered via mini-osmotic pumps for 2 months in amyloid precursor protein (APP)/PS1 transgenic mice, plaque load, tau phosphorylation, and inflammatory responses were determined. After primary mouse neurons were exposed to the conditioned medium from BV-2 microglia stimulated by Nogo, the production of Aβ and phosphorylation of tau was quantified by ELISA and western blot. Results Inhibition of the Nogo/NgR signaling pathway ameliorated pathological features including amyloid plaques and phosphorylated levels of tau in APP/PS1 mice. In addition, after treatment with the conditioned medium from BV-2 microglia stimulated by Nogo, Aβ production and tau phosphorylation in cultured neurons were increased. The conditioned medium also increased the expression of APP, its amyloidogenic processing, and the activity of GSK3β in neurons. The conditioned medium was also proinflammatory medium, and the blockage of the Nogo/NgR pathway improved the neuroinflammatory environment in APP/PS1 mice. Conclusions Taken together, the neuroinflammation mediated by Nogo/NgR pathway in microglia could directly take part in the pathological process of AD by influencing the amyloidogenesis and tau phosphorylation. These results contribute to a better understanding of AD pathogenesis and could offer a new therapeutic option for delaying the progression of AD.