Ethyl pyruvate protects against lipopolysaccharide-induced white matter injury in the developing rat brain

Ethyl pyruvate inhibits glioblastoma cells migration and invasion through modulation of NF-κB and ERK-mediated EMT

Background

Glioblastoma is a grade IV glioma with the highest degree of malignancy and extremely high incidence. Because of the poor therapeutic effect of surgery and radiochemotherapy, glioblastoma has a high recurrence rate and lethality, and is one of the most challenging tumors in the field of oncology. Ethyl pyruvate (EP), a stable lipophilic pyruvic acid derivative, has anti-inflammatory, antioxidant, immunomodulatory and other cellular protective effects. It has been reported that EP has potent anti-tumor effects on many types of tumors, including pancreatic cancer, prostate cancer, liver cancer, gastric cancer. However, whether EP has anti-tumor effect on glioblastoma or not is still unclear.

Methods

Glioblastoma U87 and U251 cells were treated with different concentrations of EP for 24 h or 48 h. CCK8 assay and Colony-Formation assay were performed to test the viability and proliferation. Wound-healing assay and Transwell assay were carried out to measure cell invasion and migration. Western blot was not only used to detect the protein expression of epithelial-mesenchymal transition (EMT)-related molecules, but also to detect the expression and activation levels of NF-κB (p65) and Extracellular Signal Regulated Kinase (ERK).

Results

In glioblastoma U87 and U251 cells treated with EP, the viability, proliferation, migration, invasion abilities were inhibited in a dose-dependent manner. EP inhibited EMT and the activation of NF-κB (p65) and ERK. With NF-κB (p65) and ERK activated, EMT, migration and invasion of U87 and U251 cells were promoted. However the activation of NF-κB (p65) and ERK were decreased, EMT, migration and invasion abilities were inhibited in U87 and U251 cells treated with EP.

Conclusion

EP inhibits glioblastoma cells migration and invasion by blocking NF-κB and ERK-mediated EMT.

Ethyl pyruvate inhibits LPS induced IPEC-J2 inflammation and apoptosis through p38 and ERK1/2 pathways

The endotoxin of Gram-negative bacteria threatens the intestinal health of livestock. Ethyl pyruvate (EP) has been shown to regulate intestinal immunity and protect against cell and tissue damage. In this study, it was first verified that EP could reduce the secretion of IL-8, TNF-α, IL-6 and IL-1β in LPS-induced IPEC-J2 cells. Then, we used RNA sequencing (RNA-seq) to analyze the differentially expressed genes (DEGs) of inflammatory factors induced by LPS in IPEC-J2 cells. It was found that LPS induced the upregulation of 377 genes and the downregulation of 477 genes compared to Vehicle; LPS+EP induced the upregulation of 258 genes and the downregulation of 240 genes compared to Vehicle; and LPS+EP induced the upregulation of 373 genes and the downregulation of 188 genes compared to LPS (fold change > 1.5 and FDR < 0.01). Their enrichment pathways included the MAPK signaling pathway, PI3K-Akt signaling pathway, Toll-like receptor signaling pathway, and other pathways. Furthermore, the mRNA level of cytokines associated with inflammation and apoptosis enriched in the MAPK pathway was verified by qRT-PCR. Western blots and immunofluorescence revealed that EP significantly inhibited phosphorylated p38 and phosphorylated-ERK1/2 protein expression levels (P < 0.05). The apoptosis due to LPS reduced by EP was significantly inhibited, as shown by Annexin V-FITC/PI staining. According to the results, EP inhibited the expression of IL-8, TNF-α, IL-6 and IL-1β as well as apoptosis by inhibiting the phosphorylation of p38 and ERK1/2 in LPS-induced IPEC-J2 cells.

Microglia-derived IL-1β contributes to axon development disorders and synaptic deficit through p38-MAPK signal pathway in septic neonatal rats

BACKGROUND

Axon development plays a pivotal role in the formation of synapse, nodes of Ranvier, and myelin sheath. Interleukin-1β (IL-1β) produced by microglia may cause myelination disturbances through suppression of oligodendrocyte progenitor cell maturation in the septic neonatal rats. Here, we explored if a microglia-derived IL-1β would disturb axon development in the corpus callosum (CC) following lipopolysaccharide (LPS) administration, and if so, whether it is associated with disorder of synapse formation in the cerebral cortex and node of Ranvier.

METHODS

Sprague-Dawley rats (1-day old) in the septic model group were intraperitoneally administrated with lipopolysaccharide (1 mg/kg) and then sacrificed for detection of IL-1β, interleukin-1 receptor (IL-1R₁), neurofilament-68, neurofilament-160, and neurofilament-200, proteolipid, synaptophysin, and postsynaptic density 95 (PSD95) expression by western blotting and immunofluorescence. Electron microscopy was conducted to observe alterations of axonal myelin sheath and synapses in the cortex, and proteolipid expression was assessed using in situ hybridization. The effect of IL-1β on neurofilament and synaptophysin expression in primary neuron cultures was determined by western blotting and immunofluorescence. P38-MAPK signaling pathway was investigated to determine whether it was involved in the inhibition of IL-1β on neurofilament and synaptophysin expression.

RESULTS

In 1-day old septic rats, IL-1β expression was increased in microglia coupled with upregulated expression of IL-1R₁ on the axons. The expression of neurofilament-68, neurofilament-160, and neurofilament-200 (NFL, NFM, NFH) and proteolipid (PLP) was markedly reduced in the CC at 7, 14, and 28 days after LPS administration. Simultaneously, cortical synapses and mature oligodendrocytes were significantly reduced. By electron microscopy, some axons showed smaller diameter and thinner myelin sheath with damaged ultrastructure of node of Ranvier compared with the control rats. In the cerebral cortex of LPS-injected rats, some axo-dendritic synapses appeared abnormal looking as manifested by the presence of swollen and clumping of synaptic vesicles near the presynaptic membrane. In primary cultured neurons incubated with IL-1β, expression of NFL, NFM, and synaptophysin was significantly downregulated. Furthermore, p38-MAPK signaling pathway was implicated in disorder of axon development and synaptic deficit caused by IL-1β treatment.

CONCLUSIONS

The present results suggest that microglia-derived IL-1β might suppress axon development through activation of p38-MAPK signaling pathway that would contribute to formation disorder of cortical synapses and node of Ranvier following LPS exposure.

Neonatal microglia: The cornerstone of brain fate

Microglia, mainly known for their role in innate immunity and modulation of neuroinflammation, play an active role in central nervous system development and homeostasis. Depending on the context and environmental stimuli, microglia adopt a broad spectrum of activation status from pro-inflammatory, associated with neurotoxicity, to anti-inflammatory linked to neuroprotection. Pro-inflammatory microglial activation is a key hallmark of white matter injury in preterm infants and is involved in developmental origin of adult neurological diseases. Characterization of neonatal microglia function in brain development and inflammation has allowed the investigation of promising therapeutic targets with potential long-lasting neuroprotective effects. True prevention of neuro-degenerative diseases might eventually occur as early as the perinatal period.

Pharmacological approaches to intervention in hypomyelinating and demyelinating white matter pathology

White matter disease afflicts both developing and mature central nervous systems. Both cell intrinsic and extrinsic dysregulation result in profound changes in cell survival, axonal metabolism and functional performance. Experimental models of developmental white matter (WM) injury and demyelination have not only delineated mechanisms of signaling and inflammation, but have also paved the way for the discovery of pharmacological approaches to intervention. These reagents have been shown to enhance protection of the mature oligodendrocyte cell, accelerate progenitor cell recruitment and/or differentiation, or attenuate pathological stimuli arising from the inflammatory response to injury. Here we highlight reports of studies in the CNS in which compounds, namely peptides, hormones, and small molecule agonists/antagonists, have been used in experimental animal models of demyelination and neonatal brain injury that affect aspects of excitotoxicity, oligodendrocyte development and survival, and progenitor cell function, and which have been demonstrated to attenuate damage and improve WM protection in experimental models of injury. The molecular targets of these agents include growth factor and neurotransmitter receptors, morphogens and their signaling components, nuclear receptors, as well as the processes of iron transport and actin binding. By surveying the current evidence in non-immune targets of both the immature and mature WM, we aim to better understand pharmacological approaches modulating endogenous oligodendroglia that show potential for success in the contexts of developmental and adult WM pathology. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.

Decreased inflammatory responses of human lung epithelial cells after ethanol exposure are mimicked by ethyl pyruvate

Background and Purpose. Leukocyte migration into alveolar space plays a critical role in pulmonary inflammation resulting in lung injury. Acute ethanol (EtOH) exposure exerts anti-inflammatory effects. The clinical use of EtOH is critical due to its side effects. Here, we compared effects of EtOH and ethyl pyruvate (EtP) on neutrophil adhesion and activation of cultured alveolar epithelial cells (A549). Experimental Approach. Time course and dose-dependent release of interleukin- (IL-) 6 and IL-8 from A549 were measured after pretreatment of A549 with EtP (2.5–10 mM), sodium pyruvate (NaP, 10 mM), or EtOH (85–170 mM), and subsequent lipopolysaccharide or IL-1beta stimulation. Neutrophil adhesion to pretreated and stimulated A549 monolayers and CD54 surface expression were determined. Key Results. Treating A549 with EtOH or EtP reduced substantially the cytokine-induced release of IL-8 and IL-6. EtOH and EtP (but not NaP) reduced the adhesion of neutrophils to monolayers in a dose- and time-dependent fashion. CD54 expression on A549 decreased after EtOH or EtP treatment before IL-1beta stimulation. Conclusions and Implications. EtP reduces secretory and adhesive potential of lung epithelial cells under inflammatory conditions. These findings suggest EtP as a potential treatment alternative that mimics the anti-inflammatory effects of EtOH in early inflammatory response in lungs.

Role of HMGB1/TLR signaling pathway in Helicobacter pylori infection

High mobility group box 1 protein (HMGB1), as a mediator of late inflammation, provides a wide therapeutic window. Extracellular HMGB1 as an endogenous injury-related molecule promotes the development of inflammation and damage by binding to its receptors. Studies have discovered that lipopolysaccharide and vacuolating cytotoxin A (VacA) of Helicobacter pylori (H. pylori) are strong stimulating factors of HMGB1 expression, and its extracellular receptors Toll-like receptors (TLRs) are closely associated with H. pylori infection and pathogenicity. Therefore, the HMGB1/TLR signaling pathway may play an important role in inflammatory response and immune abnormalities caused by H. pylori infection. This article will discuss the role of the HMGB1/TLR signaling pathway in H. pylori infection.