Estrogen Regulation of the Expression of Pain Factor NGF in Rat Chondrocytes

Mechanism of icariin for the treatment of osteoarthritis based on network pharmacology and molecular docking method

BACKGROUND

Icarin's mechanism of action in osteoarthritis (OA) was explored using network pharmacology and the GEO database, and then further validated using molecular docking.

METHODS

GEO database using network pharmacology identified differential genes in OA based on Icariin's possible targets predicted by pharmmapper database. Combining the differentially expressed genes in OA with the OA-related targets, the overlapping targets were removed. In order to determine what Icariin's core targets are for treating OA, PPI network analysis was performed using OA-related targets and possible Icariin targets. Furthermore, molecular docking was used to verify the chemical's binding to the targets. Final steps included Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of genes and genomes (KEGG) pathway enrichment analysis. Cytoscape was used to construct a network of compound-target-pathway-disease.

RESULTS

Protein-protein interactions between overlapping targets revealed 151 intersection targets based on a network analysis. The top ten targets with the highest enrichment scores were SRC, MAPK1, HSP90AA1, AKT1, PTPN11, ESR1, EGFR, RhoA, JAK2, and MAPK14. KEGG enrichment analysis showed that the pathways at which Icariin intervention occurs include the OA including FOXO signaling pathway, and estrogen signaling pathway. The GO analysis result showed that various biologic processes such as proteolysis, angiogenesis, innate immune response, and positive regulation of inflammatory response were involved in treatment. Molecular docking analysis confirmed that Icariin could bind well to the targets through intermolecular forces.

CONCLUSION

With its multi-targeting and multi-pathway characteristics, Icariin is a promising candidate drug for treating OA.

Low back pain and osteoarthritis pain: a perspective of estrogen

Low back pain (LBP) is the world's leading cause of disability and is increasing in prevalence more rapidly than any other pain condition. Intervertebral disc (IVD) degeneration and facet joint osteoarthritis (FJOA) are two common causes of LBP, and both occur more frequently in elderly women than in other populations. Moreover, osteoarthritis (OA) and OA pain, regardless of the joint, are experienced by up to twice as many women as men, and this difference is amplified during menopause. Changes in estrogen may be an important contributor to these pain states. Receptors for estrogen have been found within IVD tissue and nearby joints, highlighting the potential roles of estrogen within and surrounding the IVDs and joints. In addition, estrogen supplementation has been shown to be effective at ameliorating IVD degeneration and OA progression, indicating its potential use as a therapeutic agent for people with LBP and OA pain. This review comprehensively examines the relationship between estrogen and these pain conditions by summarizing recent preclinical and clinical findings. The potential molecular mechanisms by which estrogen may relieve LBP associated with IVD degeneration and FJOA and OA pain are discussed.

Sex-dependent variation in cartilage adaptation: from degeneration to regeneration

Despite acknowledgement in the scientific community of sex-based differences in cartilage biology, the implications for study design remain unclear, with many studies continuing to arbitrarily assign demographics. Clinically, it has been well-established that males and females differ in cartilage degeneration, and accumulating evidence points to the importance of sex differences in the field of cartilage repair. However, a comprehensive review of the mechanisms behind this trend and the influence of sex on cartilage regeneration has not yet been presented. This paper aims to summarize current findings regarding sex-dependent variation in knee anatomy, sex hormones' effect on cartilage, and cartilaginous degeneration and regeneration, with a focus on stem cell therapies. Findings suggest that the stem cells themselves, as well as their surrounding microenvironment, contribute to sex-based differences. Accordingly, this paper underscores the contribution of both stem cell donor and recipient sex to sex-related differences in treatment efficacy. Cartilage regeneration is a field that needs more research to optimize strategies for better clinical results; taking sex into account could be a big factor in developing more effective and personalized treatments. The compilation of this information emphasizes the importance of investing further research in sex differences in cartilage biology.

Estrogen-dependent regulation of transient receptor potential vanilloid 1 (TRPV1) and P2X purinoceptor 3 (P2X3): Implication in burning mouth syndrome

Sex differences in the nervous system have gained recent academic interest. While the prominent differences are observed in mood and anxiety disorders, growing number of evidences also suggest sex difference in pain perception. This review focuses on estrogen as the key molecule underlying such difference, because estrogen plays many functions in the nervous system, including modulation of transient receptor potential vanilloid 1 (TRPV1) and P2X purinoceptor 3 (P2X3), two important nociceptive receptors. Estrogen was shown in various studies to up-regulate TRPV1 expression through two distinct pathways, resulting in pro-nociceptive effect. However, estrogen alleviated pain in other studies, by down-regulating nerve growth factor (NGF)-activated pathways and TRPV1. Estrogen may also attenuate nociception by inhibiting P2X3 receptors and ATP-signaling. Understanding the mechanism underlying the pro- and anti-nociceptive effect of estrogen might be crucial to understand pathophysiology of the burning mouth syndrome (BMS), a common chronic orofacial pain disorder in menopausal women. The involvement of TRPV1 is strongly suspected because of burning sensation. Reduced estrogen level of the BMS patient might have caused increased activity of P2X3 receptors. Interestingly, the increased expression of TRPV1 and P2X3 in oral mucosa of BMS patients was reported. The combinational impact of differential modulation of TRPV1/P2X3 during menopause might be an important contributing factor of etiology of BMS. Understanding the estrogen-dependent regulation of nociceptive receptors may provide a valuable insight toward the peripheral mechanism of sex-difference in pain perception.