Apelin-13/APJ system delays intervertebral disc degeneration by activating the PI3K/AKT signaling pathway

Comprehensive analysis of abnormal methylation modification differential expression mRNAs between low-grade and high-grade intervertebral disc degeneration and its correlation with immune cells

BACKGROUND

Intervertebral disc degeneration (IDD) is an important cause of low back pain. The aim of this study is to identify the potential molecular mechanism of abnormal methylation-modified DNA in the progression of IDD, hoping to contribute to the diagnosis and management of IDD.

METHODS

Low-grade IDD (grade I-II) and high-grade IDD (grade III-V) data were downloaded from GSE70362 and GSE129789 datasets. The abnormally methylated modified differentially expressed mRNAs (DEmRNAs) were identified by differential expression analysis (screening criteria were p < .05 and |logFC| > 1) and differential methylation analysis (screening criteria were p < .05 and |δβ| > 0.1). The classification models were constructed, and the receiver operating characteristic analysis was also carried out. In addition, functional enrichment analysis and immune correlation analysis were performed and the miRNAs targeted for the abnormally methylated DEmRNAs were predicted. Finally, expression validation was performed using real-time PCR.

RESULTS

Compared with low-grade IDD, seven abnormal methylation-modified DEmRNAs (AOX1, IBSP, QDPR, ABLIM1, CRISPLD2, ACTC1 and EMILIN1) were identified in high-grade IDD, and the classification models of random forests (RF) and support vector machine (SVM) were constructed. Moreover, seven abnormal methylation-modified DEmRNAs and classification models have high diagnostic accuracy (area under the curve [AUC] > 0.8). We also found that AUC values of single abnormal methylation-modified DEmRNA were all lower than those of RF and SVM classification models. Pearson correlation analysis found that macrophages M2 and EMILIN1 had significant negative correlation, while macrophages M2 and IBSP had significant positive correlation. In addition, four targeted relationship pairs (hsa-miR-4728-5p-QDPR, hsa-miR-4533-ABLIM1, hsa-miR-4728-5p-ABLIM1 and hsa-miR-4534-CRISPLD2) and multiple signalling pathways (for example, PI3K-AKT signalling pathway, osteoclast differentiation and calcium signalling pathway) were also identified that may be involved in the progression of IDD.

CONCLUSION

The identification of abnormal methylation-modified DEmRNAs and the construction of classification models in this study were helpful for the diagnosis and management of IDD progression.

Roles of organokines in intervertebral disc homeostasis and degeneration

The intervertebral disc is not isolated from other tissues. Recently, abundant research has linked intervertebral disc homeostasis and degeneration to various systemic diseases, including obesity, metabolic syndrome, and diabetes. Organokines are a group of diverse factors named for the tissue of origin, including adipokines, osteokines, myokines, cardiokines, gastrointestinal hormones, and hepatokines. Through endocrine, paracrine, and autocrine mechanisms, organokines modulate energy homeostasis, oxidative stress, and metabolic balance in various tissues to mediate cross-organ communication. These molecules are involved in the regulation of cellular behavior, inflammation, and matrix metabolism under physiological and pathological conditions. In this review, we aimed to summarize the impact of organokines on disc homeostasis and degeneration and the underlying signaling mechanism. We focused on the regulatory mechanisms of organokines to provide a basis for the development of early diagnostic and therapeutic strategies for disc degeneration.

Beneficial effects of Apelin-13 on metabolic diseases and exercise

Apelin, a novel endogenous ligand of the G-protein-coupled receptor APJ, is encoded by the APLN gene and can be hydrolyzed into multiple subtypes, with Apelin-13 being one of the most active subtypes of the Apelin family. Recent studies have revealed that Apelin-13 functions as an adipokine that participates in the regulation of different biological processes, such as oxidative stress, inflammation, apoptosis, and energy metabolism, thereby playing an important role in the prevention and treatment of various metabolic diseases. However, the results of recent studies on the association between Apelin-13 and various metabolic states remain controversial. Furthermore, Apelin-13 is regulated or influenced by various forms of exercise and could therefore be categorized as a new type of exercise-sensitive factor that attenuates metabolic diseases. Thus, in this review, our purpose was to focus on the relationship between Apelin-13 and related metabolic diseases and the regulation of response movements, with particular reference to the establishment of a theoretical basis for improving and treating metabolic diseases.

Mechanisms of Intervertebral Disc Degeneration Treatment with Deer Antlers Based on Network Pharmacology and Molecular Docking

Background

With the aging of the population, the prevalence of IVDD increases preoperatively. How to better treat IVDD has become an important clinical issue. Deer antlers proved to have a great effect on the treatment of IVDD in many studies, but the molecular mechanism has not been clarified.

Objective

To investigate the molecular mechanism and target of deer antlers in the treatment of IVDD.

Methods

Compounds from deer antlers were collected and targets were predicted using HERB, TCMSP, TCMID, SwissADME, and SwissTargetPrediction. Collection of disease targets for IVDD was done using GeneCards, TTD, DrugBank, DisGeNET, and OMIM. Cytoscape 3.7.2, AutoDock Vina (v1.1.2), and R software were used for data analysis and the construction of network diagrams.

Results

A total of 5 active compounds from deer antlers were screened and 104 therapeutic targets were predicted. A total of 1023 IVDD disease targets were collected. Subsequently, PPI network prediction analysis was performed for disease and treatment targets, and 112 core targets were collected after screening. After obtaining the core target, we used the clusterProfiler software package of R software to carry out GO and KEGG enrichment analyses for the core target and plot the bubble maps. According to the GO enrichment results, the main biological processes of IVDD treatment by deer antlers lie in the rhythmic process, mRNA catabolic process, and G1/S transition of the mitotic cell cycle. KEGG results were mainly related to the PI3K-Akt signaling pathway, thyroid hormone signaling pathway, and Notch signaling pathway. Molecular docking results showed that estrone had the best docking results on ESR1.

Conclusion

Deer antlers are rich in various compounds that can prevent the development of IVDD by upregulating the PI3K-Akt signaling pathway and Notch signaling pathway. Its key compounds estradiol and estrone can reduce the inflammatory response and oxidative stress in tissues and organs, thus slowing down the progression of IVDD. Estrone, the active compound in deer antlers, was found by molecular docking to have good results against ESR1, the target of the disease, which may be a potential site for drug therapy.

Identification of Core Genes and Screening of Potential Targets in Intervertebral Disc Degeneration Using Integrated Bioinformatics Analysis

Background: Intervertebral disc degeneration (IDD), characterized by diverse pathological changes, causes low back pain (LBP). However, prophylactic and delaying treatments for IDD are limited. The aim of our study was to investigate the gene network and biomarkers of IDD and suggest potential therapeutic targets.

Methods: Differentially expressed genes (DEGs) associated with IDD were identified by analyzing the mRNA, miRNA, and lncRNA expression profiles of IDD cases from the Gene Expression Omnibus (GEO). The protein–protein interaction (PPI) network, Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis as well as miRNA–lncRNA–mRNA networks were conducted. Moreover, we obtained 71 hub genes and performed a comprehensive analysis including GO, KEGG, gene set enrichment analysis (GSEA), gene set variation analysis (GSVA), Disease Ontology (DO), methylation analysis, receiver operating characteristic (ROC) curve analysis, immune infiltration analysis, and potential drug identification. We finally used qRT-PCR to verify 13 significant DEGs in normal and degenerative nucleus pulposus cells (NPCs).

Results: We identified 305 DEGs closely related to IDD. The GO and KEGG analyses indicated that changes in IDD are significantly associated with enrichment of the inflammatory and immune response. GSEA analysis suggested that cell activation involved in the inflammatory immune response amide biosynthetic process was the key for the development of IDD. The GSVA suggested that DNA repair, oxidative phosphorylation, peroxisome, IL-6-JAK-STAT3 signaling, and apoptosis were crucial in the development of IDD. Among the 71 hub genes, the methylation levels of 11 genes were increased in IDD. A total of twenty genes showed a high functional similarity and diagnostic value in IDD. The result of the immune cell infiltration analysis indicated that seven genes were closely related to active natural killer cells. The most relevant targeted hub genes for potential drug or molecular compounds were MET and PIK3CD. Also, qRT-PCR results showed that ARHGAP27, C15orf39, DEPDC1, DHRSX, MGAM, SLC11A1, SMC4, and LINC00887 were significantly downregulated in degenerative NPCs; H19, LINC00685, mir-185-5p, and mir-4306 were upregulated in degenerative NPCs; and the expression level of mir-663a did not change significantly in normal and degenerative NPCs.

Conclusion: Our findings may provide new insights into the functional characteristics and mechanism of IDD and aid the development of IDD therapeutics.

Predictive Value of Apelin and Vaspin on Hemorrhagic Transformation in Patients with Acute Ischemic Stroke after Intravenous Thrombolysis and Analysis of Related Factors

BACKGROUND

Acute ischemic stroke (CIS) is a high-risk condition among the elderly, and intravenous thrombolytic therapy (ITT) is the most effective means for it. However, ITT is prone to induce hemorrhagic transformation (HT) that further threatens the life and health of patients. As paramount substances in cardiovascular and cerebrovascular diseases, adipocyte factor (Apelin) and serine protease inhibitor (Vaspin) are strongly bound up with CIS.

OBJECTIVE

To analyze the predictive significance of Apelin and Vaspin on HT in CIS patients after ITT and offer effective reference to HT prevention in the future.

METHODS

A total of 109 CIS patients treated with intravenous thrombolysis (IT) in two hospitals between June 2017 and February 2018 were enrolled. Among them, 48 patients who suffered HT after therapy were assigned to the research group (Res group) and the other 61 patients who did not suffer it after therapy were assigned to the control group (Con group). Serum Apelin, Vaspin, inflammatory factors, and oxidative stress levels were quantified, and receiver operating characteristic (ROC) curves were drawn for analyzing the predictive value of Apelin and Vaspin on HT after ITT and their associations with inflammatory factors and oxidative stress. CIS patients who suffered HT were followed up for 3 years for prognostic significance analysis of Apelin and Vaspin.

RESULTS

After ITT, the Res group showed lower Apelin and Vaspin levels than the Con group (all P < 0.05), and patients with a higher HT grade had lower Apelin and Vaspin levels (all P < 0.05). The joint detection of Apelin and Vaspin showed a sensitivity of 77.08% and a specificity of 73.77% for forecasting HT in CIS patients after thrombolytic therapy (all P < 0.001). In addition, after thrombolytic therapy, the Res group presented higher levels of interleukin-1β (IL-1β) and IL-6 as well as malondialdehyde (MDA) than the Con group, and the levels had negative associations with Apelin and Vaspin (all P < 0.05). The Res group showed a lower superoxide dismutase (SOD) level than the Con group, and the level presented a positive association with Apelin and Vaspin (all P < 0.05). According to Logistic analysis, IL-1β, IL-6, and MDA were independent risk factors for HT in CIS patients after IT, while Apelin, Vaspin, and SOD were independent protective factors (all P < 0.05). According to the follow-up results, Apelin and Vaspin demonstrated excellent value in forecasting the death of patients with both CIS and HT (P < 0.05), and their lower levels indicate a higher risk of death (all P < 0.05).

CONCLUSION

Apelin and Vaspin can help effectively forecast the occurrence of HT in CIS patients after ITT as independent protective factors of HT, so they are of a high clinical application value.