Inhibition of RIPK1 by ZJU-37 promotes oligodendrocyte progenitor proliferation and remyelination via NF-κB pathway

Electroacupuncture promotes oligodendrocyte differentiation and myelin repair in a rat model of vascular dementia: Investigation of the mechanism from NF-κB-mediated inflammation

Myelin impairment is an important cause of cognitive impairment in vascular dementia (VD). Promoting myelin regeneration has become an important improvement strategy and oligodendrocytes are important targets. This study used a multiple microinfarctions (MMI)-induced VD rat model to reveal the mechanism of myelination of oligodendrocytes in the recovery of VD model, and to investigate the intervention mechanism of electroacupuncture (EA), an effective therapeutic for VD. Initially, our transcriptomic analysis identified 52 differentially expressed genes between the sham and MMI groups. These genes are primarily associated with axonal pathways, including the synaptic vesicle cycle, glutamatergic synapse, axon guidance, and sphingolipid metabolism. Compared with sham group, inflammation, impaired differentiation of oligodendrocyte precursor cells (OPCs) and myelin damage were remarkably observable in the hippocampus of MMI group, indicating the involvement of inflammation-regulated impairment of OPCs. Accordingly, pyrrolidinedithiocarbamate (PDTC), a NF-κB inhibitor could improve learning and memory impairment, reverse the hippocampal inflammation and impairment of OPCs differentiation, and decrease myelin damage in MMI rats. Importantly, EA could also improve learning and memory, attenuate the inflammatory response in the hippocampus and facilitate the differentiation of OPCs to aid in the repair of myelin damage in MMI rats. In conclusion, our data suggest that NF-κB activation is a prohibited factor for the myelin repair, while EA might reduce NF-κB activation and promote the differentiation of OPCs to repair the myelin damage in MMI rats.

Discovery and Characterization of Novel Receptor-Interacting Protein Kinase 1 Inhibitors Using Deep Learning and Virtual Screening

Receptor-interacting protein kinase 1 (RIPK1) serves as a critical mediator of cell necroptosis and represents a promising therapeutic target for various human neurodegenerative diseases and inflammatory diseases. Nonetheless, the RIPK1 inhibitors currently reported are inadequate for clinical research due to suboptimal inhibitory activities or lack of selectivity. Consequently, there is a need for the discovery of novel RIPK1 kinase inhibitors. In this study, we integrated a deep learning model, specifically the fingerprint graph attention network (FP-GAT), with molecular docking-based virtual screening to identify potential RIPK1 inhibitors from a library comprising 13 million compounds. Out of 43 compounds procured, two compounds (designated as 24 and 41) demonstrated enzyme inhibition activity exceeding 50% at a concentration of 10 μM against RIPK1. The half-maximal inhibitory concentrations (IC50) for compounds 24 and 41 were determined to be 2.01 and 2.95 μM, respectively. Furthermore, these compounds exhibited protective effects in an HT-29 cell model of TSZ-induced necroptosis, with half-maximal effective concentrations (EC50) of 6.77 μM for compound 24 and 68.70 μM for compound 41. Finally, molecular dynamics simulations and binding free energy calculations were conducted to elucidate the molecular mechanism of compounds 24 and 41 binding to RIPK1. The results show that Met92, Met95, Ala155, and Asp156 are key residues for novel RIPK1 inhibitors. In summary, this work discovered two hit compounds targeting RIPK1, which can be further structurally modified to become promising lead compounds.

Transcriptomic profiling identifies ferroptosis and NF-κB signaling involved in α-dimorphecolic acid regulation of microglial inflammation

BACKGROUND

Microglia-evoked neuroinflammation contributes to neurodegenerative diseases such as multiple sclerosis (MS). Metabolic reprogramming, including changes in polyunsaturated fatty acids (PUFAs), plays a critical role in MS pathophysiology. Previous studies identified reduced plasma α-dimorphecolic acid (α-DIPA), a linoleic acid derivative, in MS patients. This study investigated the anti-inflammatory effects of α-DIPA on microglia and the underlying pathways.

METHODS

Lipopolysaccharide (LPS)-induced BV-2 microglial inflammation was used as an in vitro model. α-DIPA effects were assessed via ELISA for nitric oxide (NO) release, flow cytometry was used to examine cell proliferation, activation and polarization, and transcriptomic analysis was applied to identify key signaling pathways regulated by α-DIPA.

RESULTS

ELISA results showed that exogenous α-DIPA treatment significantly inhibited LPS-induced NO release from BV-2 cells in a concentration-dependent manner. Moreover, flow cytometry analysis suggested that 40 µM α-DIPA treatment significantly repressed LPS-induced BV-2 cell proliferation, activation, as well as M1 and M2 type polarization. Furthermore, transcriptome analysis revealed that exogenous α-DIPA extensively and drastically decreased the transcriptional level of numerous genes that are involved in the regulation of inflammatory responses, for instance, proinflammatory genes such as Tnf and Ccl3 related to IL-17 and TNF-α signaling. In addition, we also observed that the expression of multiple genes in NF-κB signaling were also inhibited greatly by α-DIPA, such as Nfkb2 and Nfkbia. Notably, α-DIPA robustly suppressed LPS-induced mRNA expression of abundant genes participating in the ferroptosis pathway, including Acsl4, Slc7a11, Me1, and Hmox1. Interestingly, the expressions of multiple ferroptosis-related genes were regulated specifically by α-DIPA but not LPS, such as Acsl5, Acsl6, Alox5, Cars, Dpp3, Dpp10, Slc2a5, and Slc7a1.

CONCLUSION

α-DIPA inhibits microglial inflammation likely through regulating the pathways of the ferroptosis and NF-κB signaling. These results provided preliminary evidence for α-DIPA as a potential therapeutic candidate for neurodegenerative diseases like MS.

Spotlight on necroptosis: Role in pathogenesis and therapeutic potential of intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is the leading cause of low back pain, which is one of the major factors leading to disability and severe economic burden. Necroptosis is an important form of programmed cell death (PCD), a highly regulated caspase-independent type of cell death that is regulated by receptor-interacting protein kinase 1 (RIPK1), RIPK3 and mixed lineage kinase domain-like protein (MLKL)-mediated, play a key role in the pathophysiology of various inflammatory, infectious and degenerative diseases. Recent studies have shown that necroptosis plays an important role in the occurrence and development of IDD. In this review, we provide an overview of the initiation and execution of necroptosis and explore in depth its potential mechanisms of action in IDD. The analysis focuses on the connection between NP cell necroptosis and mitochondrial dysfunction-oxidative stress pathway, inflammation, endoplasmic reticulum stress, apoptosis, and autophagy. Finally, we evaluated the possibility of treating IDD by inhibiting necroptosis, and believed that targeting necroptosis may be a new strategy to alleviate the symptoms of IDD.

The neuropathobiology of multiple sclerosis

Chronic low-grade inflammation and neuronal deregulation are two components of a smoldering disease activity that drives the progression of disability in people with multiple sclerosis (MS). Although several therapies exist to dampen the acute inflammation that drives MS relapses, therapeutic options to halt chronic disability progression are a major unmet clinical need. The development of such therapies is hindered by our limited understanding of the neuron-intrinsic determinants of resilience or vulnerability to inflammation. In this Review, we provide a neuron-centric overview of recent advances in deciphering neuronal response patterns that drive the pathology of MS. We describe the inflammatory CNS environment that initiates neurotoxicity by imposing ion imbalance, excitotoxicity and oxidative stress, and by direct neuro-immune interactions, which collectively lead to mitochondrial dysfunction and epigenetic dysregulation. The neuronal demise is further amplified by breakdown of neuronal transport, accumulation of cytosolic proteins and activation of cell death pathways. Continuous neuronal damage perpetuates CNS inflammation by activating surrounding glia cells and by directly exerting toxicity on neighbouring neurons. Further, we explore strategies to overcome neuronal deregulation in MS and compile a selection of neuronal actuators shown to impact neurodegeneration in preclinical studies. We conclude by discussing the therapeutic potential of targeting such neuronal actuators in MS, including some that have already been tested in interventional clinical trials.

Inhibition of receptor interacting protein kinase-1 (RIPK1) in the treatment of murine lupus

OBJECTIVE

Systemic lupus erythematosus (SLE) is a type of autoimmune disease that involves multiple organs involved as well as cytokine dysregulation. The treatment of SLE is still challenging due to the side effects of the different drugs used. Receptor-interacting protein kinase 1 (RIPK1) is a kinase involved in T cell homeostasis and autoinflammation. Although clinical trials have shown that RIPK1 inhibition exhibits significant efficacy in different autoimmune diseases, its role in SLE remains unclear.

METHODS

MRL/lpr lupus-prone mice received RIPK1 inhibitor ZJU37 or vehicle intraperitoneally for 10 weeks. A BM12-induced chronic graft-versus-host-disease (cGVHD) lupus-like model was introduced in RIPK1 D138N mice or C57BL/6 mice. Nephritis, serum autoantibody levels, dysregulation of adaptive immune response and cytokines were compared in treated and untreated mice.

RESULTS

ZJU37 alleviated the clinical features of the MRL/lpr mice including nephritis and anti-dsDNA antibody production. In addition, ZJU37 treatment reduced the proportion of double-negative T cells in the spleen and the cytokines of TNFα, IFN-γ, IL-6, IL-17 and IL-1β in the serum. Moreover, RIPK1 D138N mice were able to prevent the cGVHD lupus-like model from SLE attack, manifesting as anti-dsDNA antibody production, the proliferation of germinal centre B cells, plasma cells, and T follicular helper cells as well as IgG and C3 deposits in kidneys.

CONCLUSION

RIPK1 inhibition has a protective effect in the mouse model of SLE and can potentially become a new therapeutic target for SLE in humans.

Recognizing Alzheimer's disease from perspective of oligodendrocytes: Phenomena or pathogenesis?

BACKGROUND

Accumulation of amyloid beta, tau hyperphosphorylation, and microglia activation are the three highly acknowledged pathological factors of Alzheimer's disease (AD). However, oligodendrocytes (OLs) were also widely investigated in the pathogenesis and treatment for AD.

AIMS

We aimed to update the regulatory targets of the differentiation and maturation of OLs, and emphasized the key role of OLs in the occurrence and treatment of AD.

METHODS

This review first concluded the targets of OL differentiation and maturation with AD pathogenesis, and then advanced the key role of OLs in the pathogenesis of AD based on both clinic and basic experiments. Later, we extensively discussed the possible application of the current progress in the diagnosis and treatment of this complex disease.

RESULTS

Molecules involving in OLs' differentiation or maturation, including various transcriptional factors, cholesterol homeostasis regulators, and microRNAs could also participate in the pathogenesis of AD. Clinical data point towards the impairment of OLs in AD patients. Basic research further supports the central role of OLs in the regulation of AD pathologies. Additionally, classic drugs, including donepezil, edaravone, fluoxetine, and clemastine demonstrate their potential in remedying OL impairment in AD models, and new therapeutics from the perspective of OLs is constantly being developed.

CONCLUSIONS

We believe that OL dysfunction is one important pathogenesis of AD. Factors regulating OLs might be biomarkers for early diagnosis and agents stimulating OLs warrant the development of anti-AD drugs.

RIPK1 inhibitors: A key to unlocking the potential of necroptosis in drug development

Within the field of medical science, there is a great deal of interest in investigating cell death pathways in the hopes of discovering new drugs. Over the past two decades, pharmacological research has focused on necroptosis, a cell death process that has just been discovered. Receptor-interacting protein kinase 1 (RIPK1), an essential regulator in the cell death receptor signalling pathway, has been shown to be involved in the regulation of important events, including necrosis, inflammation, and apoptosis. Therefore, researching necroptosis inhibitors offers novel ways to treat a variety of disorders that are not well-treated by the therapeutic medications now on the market. The research and medicinal potential of RIPK1 inhibitors, a promising class of drugs, are thoroughly examined in this study. The journey from the discovery of Necrostatin-1 (Nec-1) to the recent advancements in RIPK1 inhibitors is marked by significant progress, highlighting the integration of traditional medicinal chemistry approaches with modern technologies like high-throughput screening and DNA-encoded library technology. This review presents a thorough exploration of the development and therapeutic potential of RIPK1 inhibitors, a promising class of compounds. Simultaneously, this review highlights the complex roles of RIPK1 in various pathological conditions and discusses potential inhibitors discovered through diverse pathways, emphasizing their efficacy against multiple disease models, providing significant guidance for the expansion of knowledge about RIPK1 and its inhibitors to develop more selective, potent, and safe therapeutic agents.

Necroptosis inhibitors: mechanisms of action and therapeutic potential

Necroptosis is a type of programmed cell death that is morphologically similar to necrosis. This type of cell death is involved in various pathophysiological disorders, including inflammatory, neurodegenerative, infectious, and malignant diseases. Receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like protein (MLKL) pseudokinase constitute the core components of the necroptosis signaling pathway and are considered the most promising targets for therapeutic intervention. The discovery and characterization of necroptosis inhibitors not only accelerate our understanding of the necroptosis signaling pathway but also provide important drug candidates for the treatment of necroptosis-related diseases. Here, we will review recent research progress on necroptosis inhibitors, mechanisms of action and their potential applications for disease treatment.

Role of Necroptosis in Central Nervous System Diseases

Necroptosis is a type of precisely regulated necrotic cell death activated in caspase-deficient conditions. Multiple factors initiate the necroptotic signaling pathway, including toll-like receptor 3/4, tumor necrosis factor (TNF), dsRNA viruses, and T cell receptors. Presently, TNF-induced necroptosis via the phosphorylation of three key proteins, receptor-interacting protein kinase 1, receptor-interacting protein kinase 3, and mixed lineage kinase domain-like protein, is the best-characterized process. Necroptosis induced by Z-DNA-binding protein 1 (ZBP-1) and toll/interleukin-1 receptor (TIR)-domain-containing adapter-inducing interferon (TRIF) plays a significant role in infectious diseases, such as influenza A virus, Zika virus, and herpesvirus infection. An increasing number of studies have demonstrated the close association of necroptosis with multiple diseases, and disrupting necroptosis has been confirmed to be effective for treating (or managing) these diseases. The central nervous system (CNS) exhibits unique physiological structures and immune characteristics. Necroptosis may occur without the sequential activation of signal proteins, and the necroptosis of supporting cells has more important implications in disease development. Additionally, necroptotic signals can be activated in the absence of necroptosis. Here, we summarize the role of necroptosis and its signal proteins in CNS diseases and characterize typical necroptosis regulators to provide a basis for the further development of therapeutic strategies for treating such diseases. In the present review, relevant information has been consolidated from recent studies (from 2010 until the present), excluding the patents in this field.