Roles of p38 MAPK signalling in intervertebral disc degeneration

In vitro and in vivo assessment of diosmetin-loaded lactoferrin-modified liposomes for brain delivery in intracerebral hemorrhage therapy

Intracerebral hemorrhage (ICH) is a serious cerebrovascular disease with high morbidity, mortality, and disability rates, largely due to neuroinflammation. Diosmetin, a natural flavonoid, has known neuroprotective effects in cerebral ischemia/reperfusion models but has been less studied in ICH. Our previous study developed diosmetin-loaded lactoferrin-modified long-circulating liposomes (Lf-Dios-Lcl), which penetrate the BBB and improve diosmetin bioavailability and brain distribution. In this study, we found that diosmetin reduced the levels of proinflammatory cytokines (IL-1β and TNF-α) and increased the level of the anti-inflammatory cytokine IL-10 in LPS-induced BV2 cells, promoting microglial polarization toward the anti-inflammatory M2 phenotype. In ICH model rats, Lf-Dios-Lcl (1 mg/kg) effectively reduced neuroinflammation, decreased IL-1β and TNF-α levels, increased IL-10 levels, and increased the proportion of CD206-positive microglia in brain tissues. Moreover, Lf-Dios-Lcl significantly downregulated p-p38 expression, suggesting that p38 signaling activation was inhibited. Overall, Lf-Dios-Lcl demonstrated brain-targeting properties and antineuroinflammatory effects by modulating microglial polarization via the p38 pathway.

Low-Frequency Cyclic Stretch Upregulates the Expression of Nuclear Factor Erythroid 2-Related Factor 2 in Human Nucleus Pulposus Cells to Inhibit the Resistin-Induced Interleukin-20 Expression

Background

Resistin may connect obesity and intervertebral disc (IVD) degeneration (IDD) and is linked with chronic inflammation. Furthermore, human IDD is characterized by high expression of interleukin-20 (IL-20). The response of human nucleus pulposus (NP) cells to tensile forces depends on both the duration and magnitude of the force applied. Nonetheless, the interactions among resistin, IL-20, and tensile forces in regulating the function of IVD NP cells remain yet to be fully understood. Nuclear factor erythroid 2-related factor 2 (NRF2) has been identified as a pleiotropic protein that enhances cellular resistance to stress stimuli and inflammatory challenges. The role of NRF2 in NP cells is not well defined, and whether tensile force influences NRF2 levels in NP cells is not known.

Aims

This study investigated the role of NRF2 in human NP cells subjected to low-frequency cyclic stretch stimulation, and the underlying mechanisms involved.

Materials and Methods

Human NP cells were cultured in chambers, serum-starved for 12 h, then subjected to 5% cyclic strain at 0.1 Hz in a bioreactor. Control chambers had no stretching. Cells were lysed for analysis post-loading.

Results

Resistin stimulation induced the expression of IL-20 in human NP cells in a dose- and time-dependent manner. The activation of the p38 mitogen-activated protein kinase, and Akt signaling pathways, as well as the production of toll-like receptor 4, are necessary to render resistin to cause the release of IL-20. In NP cells, transcription factor enzyme-linked immunosorbent assays revealed that resistin led to an increase in nuclear factor (NF)-κB-DNA binding activities. Exposure of NP cells to 5% cyclic stretch at 0.1 Hz inhibited this resistin-induced NF-κB activation and IL-20 expression.

Discussion

These findings elucidate the molecular mechanisms through which resistin induces IL-20 expression in NP cells and also demonstrate that low-frequency cyclic stretch can protect against this induction.

TNFα-reliant FSP1 up-regulation promotes intervertebral disc degeneration via caspase 3-dependent apoptosis

Intervertebral disc degeneration (IDD) is a common chronic inflammatory degenerative disease that causes lower back pain. However, the underlying mechanisms of IDD remain unclear. Ferroptosis suppressor protein 1 (FSP1) is a newly identified suppressor for ferroptosis. This study aims to investigate the role of FSP1 in IDD. Nucleus pulposus (NP) tissues in humans were collected and NP cells from rats were isolated to detect FSP1 expression pattern. The relationship between FSP1-mediated ferroptosis and apoptosis was identified using FSP1 inhibitor iFSP1. RNA sequencing was utilized to seek downstream molecules and related signaling pathways. Moreover, both exogenous recombinant FSP1 protein and endogenous small interfering RNA were implemented in this study to clarify the role of FSP1 in tumor necrosis factor-alpha (TNFα)-mediated NP cell apoptosis. Ultimately, the underlying mechanisms of FSP1-related signaling pathway in IDD were uncovered both in vitro and in vivo. As a result, FSP1 was up-regulated in human degenerative NP tissues and after TNFα stimulation. FSP1 inhibition by iFSP1 fails to trigger ferroptosis in NP cells while inhibiting TNFα-mediated apoptosis. Further experiments demonstrated that FSP1 was closely related to TNFα-reliant caspase 3 activation and mitochondrial damage. However, the exogenous addition of recombinant protein FSP1 does not induce cell death or intensify the efficacy of TNFα. Mechanically, FSP1 is involved in TNFα-mediated NF-κB signaling activation to accelerate the development of IDD. This study demonstrated that FSP1 promotes IDD through TNFα-reliant NF-κB signaling activation and caspase 3-dependent apoptosis. These findings suggested a novel therapeutic target for the treatment of IDD.

Assessing the toxicological impact of PET-MPs exposure on IVDD: Insights from network toxicology and molecular docking

Polyethylene terephthalate microplastics (PET-MPs) have emerged as a significant environmental concern due to their persistence and potential health hazards. Their role in degenerative diseases, particularly intervertebral disc degeneration (IVDD), remains poorly understood, highlighting the need for systematic evaluation of their molecular toxicity. In this study, network toxicology and molecular docking approaches were applied to investigate the toxicological mechanisms of PET-MPs-induced IVDD. Comprehensive analyses of GEO, ChEMBL, STITCH, GeneCards, and OMIM databases identified 46 potential targets associated with PET-MPs exposure, which were further refined to seven core targets, including AKT1, CASP3, and SRC, using STRING and Cytoscape software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses revealed that PET-MPs influence immune-related pathways, such as Ras signaling, apoptosis, VEGF receptor signaling, and neutrophil extracellular trap (NET) formation. Molecular docking analysis confirmed strong binding affinities of PET-MPs to these core targets, suggesting its potential to disrupt key cellular processes. These findings indicate that PET-MPs may accelerate IVDD progression by modulating apoptosis, extracellular matrix (ECM) metabolism, angiogenesis, and immune responses. This study provides valuable insights into the molecular mechanisms underlying PET-MPs-induced IVDD and highlights the utility of network toxicology in evaluating the toxicity of emerging environmental pollutants, offering a theoretical foundation for understanding the health risks of PET-MPs and guiding strategies to mitigate their impact on degenerative diseases.

Identification of KCNQ1 as a diagnostic biomarker related to endoplasmic reticulum stress for intervertebral disc degeneration based on machine learning and experimental evidence

Intervertebral disc degeneration (IDD) is a primary cause of low back pain and disability. Cellular senescence and apoptosis due to endoplasmic reticulum stress (ERS) are key in IDD pathology. Identifying biomarkers linked to ERS in IDD is crucial for diagnosis and treatment. We utilized machine learning on gene expression profiles from the Gene Expression Omnibus database to discover biomarkers associated with ERS in IDD. Gene set enrichment analysis (GSEA) and single-sample GSEA were applied to evaluate the immunological features and biological functions of these biomarkers. The expression of KCNQ1 was experimentally validated. Machine learning identified KCNQ1 as a diagnostic biomarker for ERS in IDD, confirmed by Western blotting. GSEA indicated that KCNQ1 influences IDD primarily through the Notch signaling pathway and by regulating macrophage and monocyte infiltration. KCNQ1, identified as an ERS-associated biomarker in IDD, impacts the Notch signaling pathway and immune cell infiltration, suggesting its potential as a therapeutic target for IDD. Further validation through prospective studies and additional experimental methods is necessary to elucidate the role of KCNQ1 in IDD comprehensively.

Bioactive Compounds in Osteoarthritis: Molecular Mechanisms and Therapeutic Roles

Osteoarthritis (OA) is the most common and debilitating form of arthritis. Current therapies focus on pain relief and efforts to slow disease progression through a combination of drug and non-drug treatments. Bioactive compounds derived from plants show significant promise due to their anti-inflammatory, antioxidant, and tissue-protective properties. These natural compounds can help regulate the inflammatory processes and metabolic pathways involved in OA, thereby alleviating symptoms and potentially slowing disease progression. Investigating the efficacy of these natural agents in treating osteoarthritis addresses a growing demand for natural health solutions and creates new opportunities for managing this increasingly prevalent age-related condition. The aim of this review is to provide an overview of the use of some bioactive compounds from plants in modulating the progression of osteoarthritis and alleviating associated pain.

Pip5k1γ promotes anabolism of nucleus pulposus cells and intervertebral disc homeostasis by activating CaMKII-Ampk pathway in aged mice

Degenerative disc disease (DDD) represents a significant global health challenge, yet its underlying molecular mechanisms remain elusive. This study aimed to investigate the role of type 1 phosphatidylinositol 4-phosphate 5-kinase (Pip5k1) in intervertebral disc (IVD) homeostasis and disease. All three Pip5k1 isoforms, namely Pip5k1α, Pip5k1β, and Pip5k1γ, were detectable in mouse and human IVD tissues, with Pip5k1γ displaying a highest expression in nucleus pulposus (NP) cells. The expression of Pip5k1γ was significantly down-regulated in the NP cells of aged mice and patients with severe DDD. To determine whether Pip5k1γ expression is required for disc homeostasis, we generated a Pip5k1γfl/fl; AggrecanCreERT2 mouse model for the conditional knockout of the Pip5k1γ gene in aggrecan-expressing IVD cells. Our findings revealed that the conditional deletion of Pip5k1γ did not affect the disc structure or cellular composition in 5-month-old adult mice. However, in aged (15-month-old) mice, this deletion led to several severe degenerative disc defects, including decreased NP cellularity, spontaneous fibrosis and cleft formation, and a loss of the boundary between NP and annulus fibrosus. At the molecular level, the absence of Pip5k1γ reduced the anabolism of NP cells without markedly affecting their catabolic or anti-catabolic activities. Moreover, the loss of Pip5k1γ significantly dampened the activation of the protective Ampk pathway in NP cells, thereby accelerating NP cell senescence. Notably, Pip5k1γ deficiency blunted the effectiveness of metformin, a potent Ampk activator, in activating the Ampk pathway and mitigating lumbar spine instability (LSI)-induced disc lesions in mice. Overall, our study unveils a novel role for Pip5k1γ in promoting anabolism and maintaining disc homeostasis, suggesting it as a potential therapeutic target for DDD.

Homoplantaginin alleviates intervertebral disc degeneration by blocking the NF-κB/MAPK pathways via binding to TAK1

Intervertebral disc degeneration (IVDD) is a common degenerative disease which is closely related to low back pain (LBP) and brings huge economic and social burdens. In this study, we explored the therapeutic effects of Homoplantaginin (Hom) for IVDD due to its convincing anti-inflammatory and antioxidant functions. TNF-α was used to simulate the inflammatory environment for nucleus pulposus (NP) cells in vitro. We verified that Hom could alleviate the TNF-α-induced inflammation and disturbance of ECM homeostasis through blocking the NF-κB/MAPK signaling pathways. Subsequently, we screened the binding targets of Hom and confirmed that Hom could directly bind to TAK1 and inhibit its phosphorylation to down-regulate the inflammation-related pathways. The therapeutic effects of Hom on IVDD were further validated through a needle puncture rat model in vivo. Overall, Hom was a promising small molecule for IVDD early intervention, possessing huge clinical translational value.

Extraction, purification and in vitro assessment of the antioxidant and anti-inflammatory activity of policosanols from non-psychoactive Cannabis sativa L

Policosanols (PCs) are bioactive compounds extracted from different natural waxes. In this work, the purification, characterization and assessment of the antioxidant and anti-inflammatory activity was carried out on PCs from an innovative source, i.e. a waxy material from supercritical-fluid extraction (SFE) of non-psychoactive Cannabis sativa L. (hemp) inflorescences. Starting from this material, PCs were obtained by microwave-assisted trans-esterification and hydrolysis, followed by preparative liquid chromatography under normal phase conditions. The purified product was characterized using high-performance liquid chromatography (HPLC) with an evaporative light scattering detector (ELSD). In vitro cell-free and cell-based antioxidant and anti-inflammatory assays were then performed to assess their bioactivity. HPLC-ELSED analysis of the purified mixture from hemp wax revealed C26OH and C28OH as the main compounds. In vitro assays indicated an inhibition of intracellular reactive oxygen species (ROS) production, a reduction of nuclear factor kappa B (NF-κB) activation and of the activity of the neutrophil elastase. Immunoblotting assays allowed us to hypothesize the mechanism of action of the compounds of interest, given the higher levels of MAPK-activated protein kinase 2 (MK2) and heme oxygenase-1 (HO-1) protein expression in the PC pretreated HaCaT cells. In conclusion, even if more research is needed to unveil other molecular mechanisms involved in hemp PC activity, the results of this work suggest that these compounds may have potential for use in oxinflammation processes.

Advances in the regulation of radiation-induced apoptosis by polysaccharides: A review

Polysaccharides are biomolecules composed of monosaccharides that are widely found in animals, plants and microorganisms and are of interest for their various health benefits. Cumulative studies have shown that the modulation of radiation-induced apoptosis by polysaccharides can be effective in preventing and treating a wide range of radiation injuries with safety and few side effects. Therefore, this paper summarizes the monosaccharide compositions, molecular weights, and structure-activity relationships of natural polysaccharides that regulate radiation-induced apoptosis, and also reviews the molecular mechanisms by which these polysaccharides modulate radiation-induced apoptosis, primarily focusing on promoting cancer cell apoptosis to enhance radiotherapy efficacy, reducing radiation damage to normal tissues, and inhibiting apoptosis in normal cells. Additionally, the role of gut microbiota in mediating the interaction between polysaccharides and radiation is discussed, providing innovative ideas for various radiation injuries, including hematopoiesis, immunity, and organ damage. This review will contribute to a better understanding of the value of natural polysaccharides in the field of radiation and provide guidance for the development of natural radioprotective agents and radiosensitizers.

The role of endoplasmic reticulum stress, mitochondrial dysfunction and their crosstalk in intervertebral disc degeneration

Low back pain (LBP) is a pervasive global health issue. Roughly 40% of LBP cases are attributed to intervertebral disc degeneration (IVDD). While the underlying mechanisms of IVDD remain incompletely understood, it has been confirmed that apoptosis and extracellular matrix (ECM) degradation caused by many factors such as inflammation, oxidative stress, calcium (Ca2+) homeostasis imbalance leads to IVDD. Endoplasmic reticulum (ER) stress and mitochondrial dysfunction are involved in these processes. The initiation of ER stress precipitates cell apoptosis, and is also related to inflammation, levels of oxidative stress, and Ca2+ homeostasis. Additionally, mitochondrial dynamics, antioxidative systems, disruption of Ca2+ homeostasis are closely associated with Reactive Oxygen Species (ROS) and inflammation, promoting cell apoptosis. However, numerous crosstalk exists between the ER and mitochondria, where they interact through inflammatory cytokines, signaling pathways, ROS, or key molecules such as CHOP, forming positive and negative feedback loops. Furthermore, the contact sites between the ER and mitochondria, known as mitochondria-associated membranes (MAM), facilitate direct signal transduction such as Ca2+ transfer. However, the current attention towards this issue is insufficient. Therefore, this review summarizes the impacts of ER stress and mitochondrial dysfunction on IVDD, along with the possibly potential crosstalk between them, aiming to unveil novel avenues for IVDD intervention.

Identification of 6 cuproptosis-related genes for active ulcerative colitis with both diagnostic and therapeutic values

Cuproptosis has been reported to affect a variety of diseases. Therefore, we aimed to examine the role of cuproptosis-related genes in active ulcerative colitis (UC). We acquired 2 datasets of active UC from the Gene Expression Omnibus database and created immune cell infiltrations to research immune cell dysregulation. Based on the cuproptosis gene set and differentially expressed genes (DEGs), we identified the differentially expressed genes of cuproptosis (CuDEGs). We then used 2 machine learning methods to screen hub CuDEGs. Subsequently, we performed validation on additional datasets and investigated the relationship between hub CuDEGs and drug treatments. Thirty-five controls with inactive UC and 90 patients with active UC were obtained from the training sets. A total of 9157 DEGs and 27 CuDEGs were identified, respectively. Immune cell infiltration analysis revealed that patients with active UC exhibited higher levels of activated dendritic cells and neutrophils as well as lower levels of CD8+ T cells, regulatory T cells (Tregs), and macrophage M2. A six-gene cuproptosis signature was identified using machine learning algorithms. We further validated that the 6 hub CuDEGs showed a strong correlation with active UC and acted as cuproptosis-related biomarkers of active UC. Moreover, the expression of ATOX1 was downregulated, and SUMF1, MT1G, ATP7B, FDX1, and LIAS expression was upregulated in the colonic mucosa of active UC patients who responded to golimumab or vedolizumab therapy. With the exception of ATP7B, the expression patterns of hub CuDEGs before and after infliximab treatment of patients with active UC were similar to those of golimumab and vedolizumab. Cuproptosis and active UC have a complex relationship, as illustrated in our study. ATOX1, SUMF1, MT1G, ATP7B, FDX1, and LIAS are cuproptosis-related hub genes of active UC. Our study opens new avenues for investigating UC progression and developing novel therapeutic potential targets for the disease.

IL-1β-mediated inflammatory responses in intervertebral disc degeneration: Mechanisms, signaling pathways, and therapeutic potential

Intervertebral disc degeneration (IDD) has been widely recognized as the primary cause of low back pain and is one of the major chronic diseases imposing a severe socioeconomic burden worldwide. IDD is a degenerative process characterized by inflammatory responses, and its underlying pathological mechanisms remain complex. Genetic, developmental, biochemical, and biomechanical factors contribute to the development of IDD. There is a pressing need for an effective non-surgical treatment, mainly due to the lack of comprehensive understanding of the specific mechanisms involved and the effective therapeutic targets for IDD. Recently, interleukin (IL)-1β has been recognized as an essential inflammatory factor and a key mediator of the inflammatory process in IDD. Current studies have found that IL-1β is mainly involved in IDD by affecting the metabolism of the extracellular matrix and regulating cell death (RCD), such as apoptosis, pyroptosis, and ferroptosis (a new form of RCD). Although analysis of clinical samples from different laboratories confirmed how IL-1β is induced in IDD, its specific signal transduction pathway, and the inflammatory role mediated in IDD remains unclear. This review describes the molecules and mechanisms involved in IL-1β-mediated inflammatory responses, and their roles in resolving the inflammatory process in IDD. Understanding the signaling pathways involved in IL-1β may lead to a new class of targets that promote remission for IDD patients. This review aims to provide a framework for the treatment of IDD by analyzing the signaling mechanism and function related to IL-1β, especially in terms of inflammation, matrix metabolism, and cell death regulation.