Bioinformatics analysis identifies CSF1R as an essential gene mediating Neuropathic pain - Experimental research

Quercetin, Main Active Ingredient of Moutan Cortex, Alleviates Chronic Orofacial Pain via Block of Voltage-Gated Sodium Channel

BACKGROUND

Chronic orofacial pain (COP) therapy is challenging, as current medical treatments are extremely lacking. Moutan Cortex (MC) is a traditional Chinese medicine herb widely used for chronic inflammatory diseases. However, the mechanism behind MC in COP therapy has not been well-established. The purpose of this study was to identify the active ingredients of MC and their specific underlying mechanisms in COP treatment.

METHODS

In this study, the main active ingredients and compound-target network of MC in COP therapy were identified through network pharmacology and bioinformatics analysis. Adult male Sprague-Dawley rats received oral mucosa lipopolysaccharide (LPS) injection to induce COP. Pain behaviors were evaluated by orofacial mechanical nociceptive assessment after intraganglionar injection. In vitro inflammatory cytokines in LPS-pretreated human periodontal ligament stem cells (hPDLSCs) and rat primary cultural trigeminal ganglion (TG) neurons were quantified by real-time quantitative polymerase chain reaction (RT-qPCR). Schrödinger software was used to verify the molecular docking of quercetin and critical targets. Whole-cell recording electrophysiology was used to evaluate the effect of quercetin on voltage-gated sodium (Na v ) channel in rat TG neurons.

RESULTS

The assembled compound-target network consisted of 4 compounds and 46 targets. As 1 of the active components of MC correlated with most related targets, quercetin alleviated mechanical allodynia in LPS-induced rat model of COP (mechanical allodynia threshold median [interquartile range (IQR) 0.5 hours after drug administration: vehicle 1.3 [0.6-2.0] g vs quercetin 7.0 [6.0-8.5] g, P = .002). Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that immune response and membrane functions play essential roles in MC-COP therapy. Five of the related targets were identified as core targets by protein-protein interaction analysis. Quercetin exerted an analgesic effect, possibly through blocking Na v channel in TG sensory neurons (peak current density median [IQR]: LPS -850.2 [-983.6 to -660.7] mV vs LPS + quercetin -589.6 [-711.0 to -147.8] mV, P = .006) while downregulating the expression level of proinflammatory cytokines-FOS (normalized messenger RNA [mRNA] level mean ± standard error of mean [SEM]: LPS [2. 22 ± 0.33] vs LPS + quercetin [1. 33 ± 0.14], P = .034) and TNF-α (normalized mRNA level mean ± SEM: LPS [8. 93 ± 0.78] vs LPS + quercetin [3. 77 ± 0.49], P < .0001).

CONCLUSIONS

Identifying Na v as the molecular target of quercetin clarifies the analgesic mechanism of MC, and provides ideas for the development of novel selective and efficient chronic pain relievers.

Disease-Associated Neurotoxic Astrocyte Markers in Alzheimer Disease Based on Integrative Single-Nucleus RNA Sequencing

Alzheimer disease (AD) is an irreversible neurodegenerative disease, and astrocytes play a key role in its onset and progression. The aim of this study is to analyze the characteristics of neurotoxic astrocytes and identify novel molecular targets for slowing down the progression of AD. Single-nucleus RNA sequencing (snRNA-seq) data were analyzed from various AD cohorts comprising about 210,654 cells from 53 brain tissue. By integrating snRNA-seq data with bulk RNA-seq data, crucial astrocyte types and genes associated with the prognosis of patients with AD were identified. The expression of neurotoxic astrocyte markers was validated using 5 × FAD and wild-type (WT) mouse models, combined with experiments such as western blot, quantitative real-time PCR (qRT-PCR), and immunofluorescence. A group of neurotoxic astrocytes closely related to AD pathology was identified, which were involved in inflammatory responses and pathways related to neuron survival. Combining snRNA and bulk tissue data, ZEP36L, AEBP1, WWTR1, PHYHD1, DST and RASL12 were identified as toxic astrocyte markers closely related to disease severity, significantly elevated in brain tissues of 5 × FAD mice and primary astrocytes treated with Aβ. Among them, WWTR1 was significantly increased in astrocytes of 5 × FAD mice, driving astrocyte inflammatory responses, and has been identified as an important marker of neurotoxic astrocytes. snRNA-seq analysis reveals the biological functions of neurotoxic astrocytes. Six genes related to AD pathology were identified and validated, among which WWTR1 may be a novel marker of neurotoxic astrocytes.

The CSF1-CSF1R pathway in the trigeminal ganglion mediates trigeminal neuralgia via inflammatory responses in mice

BACKGROUND

Trigeminal neuralgia (TN) is the most severe type of neuropathic pain. The trigeminal ganglion (TG) is a crucial target for the pathogenesis and treatment of TN. The colony-stimulating factor 1 (CSF1) - colony-stimulating factor 1 receptor (CSF1R) pathway regulates lower limb pain development. However, the effect and mechanism of the CSF1-CSF1R pathway in TG on TN are unclear.

METHODS

Partial transection of the infraorbital nerve (pT-ION) model was used to generate a mouse TN model. Mechanical and cold allodynia were used to measure pain behaviors. Pro-inflammatory factors (IL-6, TNF-a) were used to measure inflammatory responses in TG. PLX3397, an inhibitor of CSF1R, was applied to inhibit the CSF1-CSF1R pathway in TG. This pathway was activated in naïve mice by stereotactic injection of CSF1 into the TG.

RESULTS

The TN model activated the CSF1-CSF1R pathway in the TG, leading to exacerbated mechanical and cold allodynia. TN activated inflammatory responses in the TG manifested as a significant increase in IL-6 and TNF-a levels. After using PLX3397 to inhibit CSF1R, CSF1R expression in the TG declined significantly. Inhibiting the CSF1-CSF1R pathway in the TG downregulated the expression of IL-6 and TNF-α to reduce allodynia-related behaviors. Finally, mechanical allodynia behaviors were exacerbated in naïve mice after activating the CSF1-CSF1R pathway in the TG.

CONCLUSIONS

The CSF1-CSF1R pathway in the TG modulates TN by regulating neuroimmune responses. Our findings provide a theoretical basis for the development of treatments for TN in the TG.

Repurposing of pexidartinib for microglia depletion and renewal

Pexidartinib (PLX3397) is a small molecule receptor tyrosine kinase inhibitor of colony stimulating factor 1 receptor (CSF1R) with moderate selectivity over other members of the platelet derived growth factor receptor family. It is approved for treatment of tenosynovial giant cell tumors (TGCT). CSF1R is highly expressed by microglia, which are macrophages of the central nervous system (CNS) that defend the CNS against injury and pathogens and contribute to synapse development and plasticity. Challenged by pathogens, apoptotic cells, debris, or inflammatory molecules they adopt a responsive state to propagate the inflammation and eventually return to a homeostatic state. The phenotypic switch may fail, and disease-associated microglia contribute to the pathophysiology in neurodegenerative or neuropsychiatric diseases or long-lasting detrimental brain inflammation after brain, spinal cord or nerve injury or ischemia/hemorrhage. Microglia also contribute to the growth permissive tumor microenvironment of glioblastoma (GBM). In rodents, continuous treatment for 1-2 weeks via pexidartinib food pellets leads to a depletion of microglia and subsequent repopulation from the remaining fraction, which is aided by peripheral monocytes that search empty niches for engraftment. The putative therapeutic benefit of such microglia depletion or forced renewal has been assessed in almost any rodent model of CNS disease or injury or GBM with heterogeneous outcomes, but a tendency of partial beneficial effects. So far, microglia monitoring e.g. via positron emission imaging is not standard of care for patients receiving Pexidartinib (e.g. for TGCT), so that the depletion and repopulation efficiency in humans is still largely unknown. Considering the virtuous functions of microglia, continuous depletion is likely no therapeutic option but short-lasting transient partial depletion to stimulate microglia renewal or replace microglia in genetic disease in combination with e.g. stem cell transplantation or as part of a multimodal concept in treatment of glioblastoma appears feasible. The present review provides an overview of the preclinical evidence pro and contra microglia depletion as a therapeutic approach.

S-Ketamine Improves Slow Wave Sleep and the Associated Changes in Serum Protein Among Gynecological Abdominal Surgery Patients: A Randomized Controlled Trial

Purpose

This study aims to evaluate the effect of S-ketamine on slow wave sleep (SWS) and the related changes in serum protein in gynecological patients after open abdomen surgery.

Methods

This was a randomized controlled trial. One hundred gynecological patients undergoing open abdomen surgery were randomized into an S-ketamine group (group S) or placebo group (0.9% saline; group C). During operation, patients in group S received adjuvant S-ketamine infusion (0.2 mg·kg-1·h-1) while those in group C received 0.9% saline. All patients were connected to patient-controlled intravenous analgesia (PCIA) pump in the end of the surgery and the patients in group S with an additional S-ketamine in PCIA pump. Polysomnogram (PSG) was monitored during the next night after surgery with PCIA pump. Blood samples were collected for proteomic analysis at 6:00 AM after PSG monitoring. The primary outcome was the percentage of SWS (also known as stage 3 non-rapid eye movement sleep, stage N3) on the next night after surgery, and the secondary outcome was subjective sleep quality, pain scores, and the changes in serum proteomics.

Results

Complete polysomnogram recordings were obtained from 64 study participants (31 in group C and 33 in group S). The administration of S-ketamine infusion resulted in a significant increase in the percentage of SWS/N3 compared to the control group (group C, median (IQR [range]), 8.9 (6.3, 12.5); group S, median (IQR [range]), 15.6 (12.4, 18.8), P<0.001). However, subjective evaluations of sleep quality revealed no significant variances between the two groups. The protein affected by S-ketamine was primarily associated with posttranslational modification, protein turnover, carbohydrate transport, and metabolism.

Conclusion

In patients undergoing open gynecological surgery, S-ketamine enhanced the percentage of objective sleep of SWS during the next night after surgery. Additionally, there were differences observed in serum protein levels between the two groups.

Trial Registration

ChiCTR2200055180. Registered on 02/01/2022.

Molecular mechanism analysis of m6A modification-related lncRNA-miRNA-mRNA network in regulating autophagy in acute pancreatitis

This study aims to explore the molecular mechanism of N6-methyladenosine (m6A) modification-related long noncoding RNA (lncRNA)-microRNA (miRNA)-messenger RNA (mRNA) network in regulating autophagy and affecting the occurrence and development of acute pancreatitis (AP). RNA-seq datasets related to AP were obtained from Gene Expression Omnibus (GEO) database and merged after batch effect removal. lncRNAs significantly related to m6A in AP, namely candidate lncRNA, were screened by correlation analysis and differential expression analysis. In addition, candidate autophagy genes were screened through the multiple databases. Furthermore, the key pathways for autophagy to play a role in AP were determined by functional enrichment analysis. Finally, we predicted the miRNAs binding to genes and lncRNAs through TargetScan, miRDB and DIANA TOOLS databases and constructed two types of lncRNA-miRNA-mRNA regulatory networks mediated by upregulated and downregulated lncRNAs in AP. Nine lncRNAs related to m6A were differentially expressed in AP, and 21 candidate autophagy genes were obtained. Phosphoinositide 3-kinase (PI3K)-Akt signaling pathway and Forkhead box O (FoxO) signaling pathway might be the key pathways for autophagy to play a role in AP. Finally, we constructed a lncRNA-miRNA-mRNA regulatory network. An upregulated lncRNA competitively binds to 13 miRNAs to regulate 6 autophagy genes, and a lncRNA-miRNA-mRNA regulatory network in which 2 downregulated lncRNAs competitively bind to 7 miRNAs to regulate 2 autophagy genes. m6A modification-related lncRNA Pvt1, lncRNA Meg3 and lncRNA AW112010 may mediate the lncRNA-miRNA-mRNA network, thereby regulating autophagy to affect the development of AP.