Murine astrocytes are responsive to the pro-inflammatory effects of IL-20

Neuro-Vulnerability in Energy Metabolism Regulation: A Comprehensive Narrative Review

This comprehensive narrative review explores the concept of neuro-vulnerability in energy metabolism regulation and its implications for metabolic disorders. The review highlights the complex interactions among the neural, hormonal, and metabolic pathways involved in the regulation of energy metabolism. The key topics discussed include the role of organs, hormones, and neural circuits in maintaining metabolic balance. The review investigates the association between neuro-vulnerability and metabolic disorders, such as obesity, insulin resistance, and eating disorders, considering genetic, epigenetic, and environmental factors that influence neuro-vulnerability and subsequent metabolic dysregulation. Neuroendocrine interactions and the neural regulation of food intake and energy expenditure are examined, with a focus on the impact of neuro-vulnerability on appetite dysregulation and altered energy expenditure. The role of neuroinflammation in metabolic health and neuro-vulnerability is discussed, emphasizing the bidirectional relationship between metabolic dysregulation and neuroinflammatory processes. This review also evaluates the use of neuroimaging techniques in studying neuro-vulnerability and their potential applications in clinical settings. Furthermore, the association between neuro-vulnerability and eating disorders, as well as its contribution to obesity, is examined. Potential therapeutic interventions targeting neuro-vulnerability, including pharmacological treatments and lifestyle modifications, are reviewed. In conclusion, understanding the concept of neuro-vulnerability in energy metabolism regulation is crucial for addressing metabolic disorders. This review provides valuable insights into the underlying neurobiological mechanisms and their implications for metabolic health. Targeting neuro-vulnerability holds promise for developing innovative strategies in the prevention and treatment of metabolic disorders, ultimately improving metabolic health outcomes.

Upregulation of neuronal progranulin mediates the antinociceptive effect of trimetazidine in paclitaxel-induced peripheral neuropathy: Role of ERK1/2 signaling

Neuronal progranulin (PGRN) overexpression is an endogenous adaptive pain defense following nerve injury. It allows the survival of injured neurons to block enhanced nociceptive responses. Trimetazidine (TMZ) is widely used by cardiac patients as an anti-anginal drug, reflecting its anti-ischemic property. TMZ promotes axonal regeneration of sciatic nerves after crush injury. This study explored the interplay between PGRN and extracellular signal-regulated kinases (ERK1/2) to address mechanisms underlying neuropathic pain alleviation following paclitaxel (PTX) administration. Rats were given four injections of PTX (2 mg/kg, i.p.) every other day. Two days after the last dose, rats received TMZ (25 mg/kg) with or without the ERK inhibitor, PD98059, daily for 21 days. TMZ preserved the integrity of myelinated nerve fibers, as evidenced by an obvious reduction in axonal damage biomarkers. Accordingly, it alleviated PTX-evoked thermal, cold, and mechanical hyperalgesia/allodynia. TMZ also promoted ERK1/2 phosphorylation with a profound upsurge in PGRN content. These effects were associated with a substantial increase in Notch1 receptor gene expression and a prominent anti-inflammatory effect with a marked increase in mRNA expression of secretory leukocyte protease inhibitor. Further, TMZ decreased oxidative stress and caspase-3 activity in the sciatic nerve. Conversely, co-administration of PD98059 completely abolished these beneficial effects. Thus, the robust antinociceptive effect of TMZ is largely attributed to upregulating PGRN and Notch1 receptors via ERK1/2 activation.

Expression of IL-20 Receptor Subunit β Is Linked to EAE Neuropathology and CNS Neuroinflammation

Considerable clinical evidence supports that increased blood-brain barrier (BBB) permeability is linked to immune extravasation of CNS parenchyma during neuroinflammation. Although BBB permeability and immune extravasation are known to be provoked by vascular endothelial growth factor-A (i.e., VEGF-A) and C-X-C motif chemokine ligand 12 (CXCL12), respectively, the mechanisms that link both processes are still elusive. The interleukin-20 (i.e., IL-20) cytokine signaling pathway was previously implicated in VEGF-mediated angiogenesis and is known to induce cellular response by way of signaling through IL-20 receptor subunit β (i.e., IL-20RB). Dysregulated IL-20 signaling is implicated in many inflammatory pathologies, but it's contribution to neuroinflammation has yet to be reported. We hypothesize that the IL-20 cytokine, and the IL cytokine subfamily more broadly, play a key role in CNS neuroinflammation by signaling through IL-20RB, induce VEGF activity, and enhance both BBB-permeability and CXCL12-mediated immune extravasation. To address this hypothesis, we actively immunized IL-20RB^-/- mice and wild-type mice to induce experimental autoimmune encephalomyelitis (EAE) and found that IL-20RB^-/- mice showed amelioration of disease progression compared to wild-type mice. Similarly, we passively immunized IL-20RB^-/- mice and wild-type mice with myelin-reactive Th1 cells from either IL-20RB^-/- and wild-type genotype. Host IL-20RB^-/- mice showed lesser disease progression than wild-type mice, regardless of the myelin-reactive Th1 cells genotype. Using multianalyte bead-based immunoassay and ELISA, we found distinctive changes in levels of pro-inflammatory cytokines between IL-20RB^-/- mice and wild-type mice at peak of EAE. We also found detectable levels of all cytokines of the IL-20 subfamily within CNS tissues and specific alteration to IL-20 subfamily cytokines IL-19, IL-20, and IL-24, expression levels. Immunolabeling of CNS region-specific microvessels confirmed IL-20RB protein at the spinal cord microvasculature and upregulation during EAE. Microvessels isolated from macaques CNS tissues also expressed IL-20RB. Moreover, we identified the expression of all IL-20 receptor subunits: IL-22 receptor subunit α-1 (IL-22RA1), IL-20RB, and IL-20 receptor subunit α (IL-20RA) in human CNS microvessels. Notably, human cerebral microvasculature endothelial cells (HCMEC/D3) treated with IL-1β showed augmented expression of the IL-20 receptor. Lastly, IL-20-treated HCMEC/D3 showed alterations on CXCL12 apicobasal polarity consistent with a neuroinflammatory status. This evidence suggests that IL-20 subfamily cytokines may signal at the BBB via IL-20RB, triggering neuroinflammation.

Targeting interleukin-20 alleviates paclitaxel-induced peripheral neuropathy

The role of immune mediators, including proinflammatory cytokines in chemotherapy-induced peripheral neuropathy (CIPN), remains unclear. Here, we studied the contribution of interleukin-20 (IL-20) to the development of paclitaxel-induced peripheral neuropathy. Increased serum levels of IL-20 in cancer patients with chemotherapy were accompanied by increased CIPN risk. In mouse models, proinflammatory IL-20 levels in serum and dorsal root ganglia fluctuated with paclitaxel treatment. Blocking IL-20 with the neutralizing antibody or genetic deletion of its receptors prevented CIPN, alleviated peripheral nerve damage, and dampened inflammatory responses, including macrophage infiltration and cytokine release. Mechanistically, paclitaxel upregulated IL-20 through dysregulated Ca homeostasis, which augmented chemotherapy-induced neurotoxicity. Importantly, IL-20 suppression did not alter paclitaxel efficacy on cancer treatment both in vitro and in vivo. Together, targeting IL-20 ameliorates paclitaxel-induced peripheral neuropathy by suppressing neuroinflammation and restoring Ca homeostasis. Therefore, the anti-IL-20 monoclonal antibody is a promising therapeutic for the prevention and treatment of paclitaxel-induced neuropathy.

Anti-IL-20 antibody improved motor function and reduced glial scar formation after traumatic spinal cord injury in rats

BACKGROUND

Spinal cord injury (SCI) causes devastating neurological consequences, which can result in partial or total paralysis. Irreversible neurological deficits and glial scar formation are characteristic of SCI. Inflammatory responses are a major component of secondary injury and play a central role in regulating the pathogenesis of SCI. IL-20 is a proinflammatory cytokine involved in renal fibrosis and liver cirrhosis through its role in upregulating TGF-β1 production. However, the role of IL-20 in SCI remains unclear. We hypothesize that IL-20 is upregulated after SCI and is involved in regulating the neuroinflammatory response.

METHODS

The expression of IL-20 and its receptors was examined in SCI rats. The regulatory roles of IL-20 in astrocytes and neuron cells were examined. The therapeutic effects of anti-IL-20 monoclonal antibody (mAb) 7E in SCI rats were evaluated.

RESULTS

Immunofluorescence staining showed that IL-20 and its receptors were expressed in astrocytes, oligodendrocytes, and microglia in the spinal cord after SCI in rats. In vitro, IL-20 enhanced astrocyte reactivation and cell migration in human astrocyte (HA) cells by upregulating glial fibrillary acidic protein (GFAP), TGF-β1, TNF-α, MCP-1, and IL-6 expression. IL-20 inhibited cell proliferation and nerve growth factor (NGF)-derived neurite outgrowth in PC-12 cells through Sema3A/NRP-1 upregulation. In vivo, treating SCI rats with anti-IL-20 mAb 7E remarkably inhibited the inflammatory responses. 7E treatment not only improved motor and sensory functions but also improved spinal cord tissue preservation and reduced glial scar formation in SCI rats.

CONCLUSIONS

IL-20 might regulate astrocyte reactivation and axonal regeneration and result in the secondary injury in SCI. These findings demonstrated that IL-20 may be a promising target for SCI treatment.

LncRNA NEAT1 affects inflammatory response by targeting miR-129-5p and regulating Notch signaling pathway in epilepsy

It is crucial to understand the molecular mechanisms involved in epileptogenesis. This study aims to investigate the role of lncRNA NEAT1, miR-129-5p and Notch signaling pathway in epilepsy. In this research, temporal lobe tissues were collected from patients with epilepsy and healthy controls. The CTX-TNA cells were treated with IL-1β to establish as epilepsy cell model, which were then manipulated the expression level of NEAT1, miR-129-5p and Notch1 to investigate their roles in the epilepsy progression. The expression levels of RNA and protein in temporal lobe tissues and epilepsy cell model were determined by RT-qPCR, western blotting or ELISA, respectively. MTT assay was utilized to analyze the cell viability. Dual-luciferase reporter assay was used to explore the interaction relationship between lncRNA NEAT1, miR-129-5p and Notch1. Silencing NEAT1 significantly reduced the expression levels of IL-6, COX-2 and TNF-α in epilepsy cell model. The overexpression of NEAT1 suppressed the expression level of miR-129-5p. Inhibiting miR-129-5p significantly increased the expression of IL-6, COX-2, TNF-α and Notch1. Furthermore, the expression levels of IL-6, COX-2 and TNF-α were increased after overexpressing Notch1 in miR-129-5p mimics-treated cells. The expression levels of Notch1, JAG1, and HES1 were decreased after transfecting with sh-NEAT1. However, compared with sh-NEAT1 group, the expression levels of Notch1, JAG1, HES1, IL-6 and TNF-α were reversed by miR-129-5p inhibition or Notch1 overexpression. The present study verified that lncRNA NEAT1 affected inflammatory response of epilepsy by suppressing miR-129-5p and further regulating Notch signaling pathway in IL-1β-induced epilepsy cell model.Abbreviations: CNS: Central nervous system; lncRNAs: Long noncoding RNAs; NEAT1: Nuclear-enriched abundant transcript 1; miRNAs: MicroRNAs; ATCC: American Type Culture Collection; DMEM: Dulbecco's Modified Eagle Medium; FBS: Fetal bovine serum; ELISA: Enzyme-linked immunosorbent assay; RT-qPCR: Reverse transcription-quantitative polymerase chain reaction; SD: Standard deviation; ANOVA: Analysis of variance; LPS: Ligand lipopolysaccharide; GLO1: Glyoxalase I.

The MicroRNA Centrism in the Orchestration of Neuroinflammation in Neurodegenerative Diseases

MicroRNAs (miRNAs) are small non-coding RNAs with a unique ability to regulate the transcriptomic profile by binding to complementary regulatory RNA sequences. The ability of miRNAs to enhance (proinflammatory miRNAs) or restrict (anti-inflammatory miRNAs) inflammatory signalling within the central nervous system is an area of ongoing research, particularly in the context of disorders that feature neuroinflammation, including neurodegenerative diseases (NDDs). Furthermore, the discovery of competing endogenous RNAs (ceRNAs) has led to an increase in the complexity of miRNA-mediated gene regulation, with a paradigm shift from a unidirectional to a bidirectional regulation, where miRNA acts as both a regulator and is regulated by ceRNAs. Increasing evidence has revealed that ceRNAs, including long non-coding RNAs, circular RNAs, and pseudogenes, can act as miRNA sponges to regulate neuroinflammation in NDDs within complex cross-talk regulatory machinery, which is referred to as ceRNA network (ceRNET). In this review, we discuss the role of miRNAs in neuroinflammatory regulation and the manner in which cellular and vesicular ceRNETs could influence neuroinflammatory dynamics in complex multifactorial diseases, such as NDDs.