IκBα Degradation Research Articles

Training Status Influences Regulation of Muscle and PBMC TLR4 Expression and Systemic Cytokine Responses to Vigorous Endurance Exercise.

A bout of vigorous endurance exercise transiently activates Toll-like receptor 4 (TLR4) and reduces TLR4 protein expressed on peripheral blood mononuclear cells (PBMCs). Endurance training, on the other hand, reduces TLR4-mediated signaling and minimizes the physiological stress imposed by exercise. Less is known about what occurs in skeletal muscle regarding TLR4 regulation and signaling. Therefore, this study aimed to investigate the regulation of TLR4 expressed in different tissue types (PBMCs and skeletal muscle samples) between endurance-trained and untrained men following vigorous endurance exercise and determine the effect of training status on cytokine responses associated with TLR4 activation. Endurance-trained (n = 7) and untrained (n = 5) men cycled for 1-hr at their respiratory compensation point, with blood and skeletal muscle samples collected pre- and 3-hours post-exercise. In response to vigorous exercise, untrained men experienced a decrease in inhibitor of κBα (IκBα) protein (suggesting IκB degradation and the activation of TLR4-associated transcription factor NF-κB) and TLR4 protein levels, along with a simultaneous increase in TLR4 mRNA expression in both skeletal muscle and PBMCs. Moreover, this exercise session led to elevated levels of circulating interleukin-6, tumor necrosis factor-α, and interleukin-1β. Collectively, these results suggest a heightened TLR4-mediated signaling pathway in untrained men. However, no changes in these targets were observed in endurance-trained men, possibly indicating a potential mechanism by which regular endurance training blunts systemic inflammation. These findings highlight the potential of endurance training to mitigate TLR4-mediated signaling, such as systemic inflammation, and shed light on the effects of exercise on TLR4 expression in PBMCs and skeletal muscle.

Isoginkgetin Inhibits RANKL-induced Osteoclastogenesis and Alleviates Bone Loss

Osteoporosis is characterized by excessive osteoclast activity leading to bone loss, decreased bone mineral density, and increased susceptibility to fractures. Through in vivo/vitro experiments, along with network pharmacology analysis, we aimed to explore the underlying mechanisms of Isoginkgetin (IGG) in inhibiting osteoclastogenesis, providing valuable insights for further research in the future. Firstly, we ascertained the safe concentration of IGG stimulation on BMMs, followed by a systematic exploration of the concentration gradient at which IGG inhibited osteoclastogenesis using TRAP analysis. An osteoporosis model was established to further validate the in vitro experimental findings by combining Micro-CT and immunohistochemical analysis. The results show that IGG did not exhibit cytotoxicity or proliferative effects on BMMs at concentrations equal to or less than 10 μM. Additionally, IGG inhibited the activity of osteoclastogenesis and bone resorption function at lower concentrations. RT-PCR and Western Blot results demonstrated that IGG could downregulate genes and proteins associated with osteoclastogenesis. The Western Blot results also showed that IGG inhibited the phosphorylation expression of P38, ERK, and P65 in the MAPK and NF-κB pathways. At the same time, it rescued the degradation of IκB-α at 15 and 60 min. IGG can also impact the relative expression levels of oxidative proteins such as SOD-1, HO-1, and catalase, thereby influencing cellular equilibrium and stress levels, ultimately inhibiting the formation of mature OC. In vivo experiments demonstrated that IGG alleviated bone loss caused by osteoclasts and improved relevant parameters of trabecular bone. So, IGG effectively attenuated osteoclastogenesis, and improved bone density, thereby portraying its role in osteoporosis management.

Molecular Mechanisms of Curdlan-Induced Suppression of NFATc1 Expression in Osteoclasts.

Osteoclasts derived from hematopoietic stem cells express immunoreceptors on their cell surface. Previously, we showed that the β-glucan curdlan suppressed osteoclastogenesis via binding to dectin-1, a pattern recognition receptor. Curdlan negatively regulates osteoclast differentiation and bone resorption capacity by suppressing the expression of nuclear factor of activated T cells 1 (NFATc1), a master factor for osteoclast differentiation, in a dectin-1-dependent manner; however, the mechanism involved in this process has not yet been fully elucidated. In this study, we aimed to elucidate the molecular mechanism involved in the suppression of RANKL-induced osteoclast differentiation by curdlan. Real-time RT-qPCR results showed that curdlan suppressed the expression of NFATc1 in cells of the osteoclast progenitor cell line RAW264.7 overexpressing dectin-1 (d-RAW cells), without altering the expression of negative regulators. Therefore, we examined the effect of curdlan on the NF-κB pathway, which is important for the induction of NFATc1 expression. Western blot analysis results showed that curdlan addition suppressed RANKL-induced NF-κB activation in the vector control line (c-RAW) cells with low expression of dectin-1, in d-RAW cells, and the parental RAW264.7 (RAW) cells. The results of tartrate-resistant alkaline phosphatase staining and real-time RT-qPCR showed that curdlan addition suppressed osteoclast differentiation in RAW cells, suggesting the presence of a dectin-1-independent modification system. Finally, we focused on the complement receptor 3 (CR3), which binds β-glucan, and revealed that blocking the binding of β-glucan to the CD11b molecule, a component of CR3, by neutralizing antibody, recovered the suppression of IκBα degradation by curdlan. These results suggest that the suppression of osteoclast differentiation by curdlan involves not only the dectin-1-dependent pathway but also the negative regulation of NFATc1 via modification of the NF-κB pathway via CR3 recognition. The results of this study may aid to establish treatment methods for metabolic bone diseases and inflammatory bone destruction and to clarify their pathogenesis.

Anti-Inflammatory Effects and Metabolomic Analysis of Ilex Rotunda Extracted by Supercritical Fluid Extraction.

Ilex rotunda is a famous medicinal plant with many ethnopharmacological uses. It is traditionally employed for treating inflammation and cardiovascular diseases. In this study, we established green technology to extract the leaves and twigs of I. rotunda. The obtained extracts and their fractions were evaluated for their anti-inflammatory potential. In cytokine assays, the extract, n-hexane (H), methylene chloride (MC), and EtOAc (E) fractions of the twigs of I. rotunda significantly inhibited lipopolysaccharide (LPS)-induced nitric oxide (NO), interleukin (IL)-6, and tumor necrosis factor (TNF)-α production in RAW264.7 macrophages. Furthermore, the extract, H, and MC fractions of the leaves of I. rotunda modulated cytokine expression by downregulating LPS-induced NO, IL-6, and TNF-α production in RAW264.7 macrophages. Western blotting analysis revealed that the extracts and fractions of the leaves and twigs of I. rotunda inhibited inflammatory cytokines by inactivating nuclear factor kappa B (NFκB) action by reducing the phosphorylation of transcript factor (p65) and nuclear factor-kappa B inhibitor alpha (IκBα) degradation, or by inactivating mitogen-activated protein kinase (MAPK) through the p38 or ERK signaling pathways via the active ingredients of the leaves and twigs of I. rotunda. Ultra-high-resolution liquid chromatography-Orbitrap mass analysis (UHPLC-ESI-Orbitrap-MS/MS)-based molecular networking, in cooperation with social open platform-guided isolation and dereplication, led to the identification of metabolites in this plant. Our findings indicate that the leaves and twigs of I. rotunda could be promising candidates for developing therapeutic strategies to treat anti-inflammatory diseases.

Wedelolactone alleviates inflammation and cartilage degeneration by suppressing the NF-κB signaling pathway in osteoarthritis

Inflammation and extracellular matrix (ECM) degradation are two major factors involved in the pathogenesis of osteoarthritis (OA). Wedelolactone, a natural compound classified as a coumestan, is isolated from the medicinal plants Eclipta alba and Wedelia calendulacea. In this study, we assessed the protective effects of Wedelolactone on chondrocytes in OA. Our findings show that pretreatment with Wedelolactone effectively inhibited the IL-1β-induced upregulation of COX‑2, iNOS, TNF-α, and IL6 in chondrocytes, contributing to inflammation suppression. Moreover, pretreatment with Wedelolactone followed by IL-1β treatment significantly increased the expression of Collagen II and SOX9, while decreasing the expression of Adamts5, MMP1, MMP3, and MMP13, thereby promoting ECM protection. Through Network pharmacology Analysis, we identified 14 key targets that link Wedelolactone and OA. GO and KEGG pathway analysis suggested that Wedelolactone primarily impacted OA by targeting inflammatory responses, particularly the NF-κB signaling pathway. Further studies demonstrated Wedelolactone prevented IL-1β-induced activation of NF-κB signaling pathway by inhibiting the translocation of p65 and the preventing the degradation of IκBα in human chondrocytes. Molecular docking studies also indicated that Wedelolactone can directly bind to the NF-κB complex, thereby inhibited the nuclear localization of p65. In vivo experiments demonstrated that Wedelolactone can alleviate cartilage damage in DMM mice model. In summary, Wedelolactone appears to mitigate inflammation and cartilage degeneration by suppressing the NF-κB signaling pathway, thereby alleviating OA progression. Our results suggested Wedelolactone may offer therapeutic advantages for OA treatment.

Anti-inflammatory effects of phytosphingosine-regulated cytokines and NF-kB and MAPK mechanism.

Phytosphingosine (PHS) is a major component of the skin barrier and a multifunctional physiologically active substance. This study aimed to investigate the types of cytokines regulated by PHS, their anti-skin inflammatory effects, and their anti-inflammatory mechanisms. RAW264.7 cells stimulated with Lipopolysaccharides (LPS) were treated with PHS to measure inflammatory factors such as nitric oxide (NO) and prostaglandin E2 (PGE2), and gene expressions of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX2) were confirmed by q-PCR. Cytokines regulated by PHS against LPS-induced inflammation were found through cytokine array, and each factor was reconfirmed through ELISA. Western blot was performed to confirm anti-inflammatory mechanism of Iκbα and MAPK. To confirm anti-skin inflammatory efficacy, HaCaT cells stimulated with TNF-α/IFN-γ were treated with PHS, and TARC, IL-6, and IL-8 were detected by ELISA. PHS suppressed the gene expression of iNOS and COX2, which were increased by LPS, and suppressed NO and PGE2 production. Through cytokine array, it was confirmed that IL-6, IL-10, IL-27 p28/IL-30, IP-10, I-TAC, MCP-5, and TIMP-1 increased by LPS were decreased by PHS. PHS inhibited NF-κB signaling by inhibiting LPS-induced NF-κB nuclear migration and p-Iκbα-mediated Iκbα degradation, and inhibited p38, ERK, and JNK signaling pathways. PHS reduced the production of TARC, IL-6, and IL-8 increased by TNF-α/IFN-γ. These results indicate PHS has anti-inflammatory effects via the suppression of inflammatory factors and pro-inflammatory cytokines through the NF-κB and MAPK pathways. Moreover, these results may explain beneficial effects of PHS in the treatment of skin inflammatory conditions induced by TNF-α/IFN-γ.

β-glucan regulates the intestinal immunity of pearl gentian grouper via the nuclear factor kappa B signaling pathway

The preceding study observed that yeast β-glucan supplementation enhanced intestinal health and augmented disease resistance in pearl gentian grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀), which occurred concurrently with the activation of the nuclear factor kappa B (NFκB) signaling pathway. Thus, we hypothesized that β-glucan improves intestinal health in grouper by modulating the NFκB pathway. Accordingly, the present study examined the effects of NFκB pathway disruption using a specific inhibitor on the intestinal health of pearl gentian grouper that had been injected with β-glucan. The experimental groups were as follows, (1) CD group: PBS injected; (2) βG group: β-glucan injected at a dose of 80 mg/kg; (3) PDTC group: NFκB inhibitor PDTC injected at a dose of 30 mg/kg; (4) βG + PDTC group: a combination of β-glucan (80 mg/kg) and PDTC (30 mg/kg) injected together. The results demonstrated that β-glucan-induced increases in mRNA expression levels of NFκB inhibitor α (iκbα) and p65, the degradation and phosphorylation of IκBα, and the phosphorylation of NFκB p65 were significantly inhibited following NFκB inhibition using PDTC in the intestine of grouper. The PDTC injection resulted in a significant reduction in the β-glucan-induced increase in mucin levels. The β-glucan-induced elevation of alkaline phosphatase (AKP) activity, component 3 (C3) content, and inflammatory factors were significantly suppressed following NFκB inhibition. The βG + PDTC treatment resulted in a restoration of catalase (CAT) enzyme activity to the level observed in the CD treatment, while total antioxidant capacity (T-AOC) was decreased to the level of the βG treatment. The β-glucan-induced downregulation of caspase8 (casp8) was reversed following NFκB inhibition, as well as the mRNA levels of casp3 and casp9 being elevated to a greater extent. In conclusion, the β-glucan-regulated intestinal immunity in grouper may be mediated by the NFκB pathway. Furthermore, the inhibitory effect of β-glucan on apoptosis and oxidative stress may not be related to the NFκB signaling pathway.

Combination of bortezomib and venetoclax targets the pro-survival function of LMP-1 and EBNA-3C of Epstein-Barr virus in spontaneous lymphoblastoid cell lines.

Epstein-Barr virus (EBV) manipulates the ubiquitin-proteasome system and regulators of Bcl-2 family to enable the persistence of the virus and survival of the host cells through the expression of viral proteins in distinct latency patterns. We postulate that the combination of bortezomib (proteasome inhibitor) and venetoclax (Bcl-2 inhibitor) [bort/venetoclax] will cause synergistic killing of post-transplant lymphoproliferative disorder (PTLD) through targeting the pro-survival function of latent viral proteins such as latent membrane protein-1 (LMP-1) and EBV nuclear antigen-3C (EBNA-3C). Bort/venetoclax could synergistically kill spontaneous lymphoblastoid cell lines (sLCLs) derived from patients with PTLD and EBV-associated hemophagocytic lymphohistiocytosis by inducing DNA damage response, apoptosis and G1-S cell cycle arrest in a ROS-dependent manner. Bortezomib potently induced the expression of Noxa, a pro-apoptotic initiator and when combined with venetoclax, inhibited Mcl-1 and Bcl-2 simultaneously. Bortezomib prevented LMP-1 induced proteasomal degradation of IκBα leading to the suppression of the NF-κB signaling pathway. Bortezomib also rescued Bcl-6 from EBNA-3C mediated proteasomal degradation thus maintaining the repression of cyclin D1 and Bcl-2 causing G1-S arrest and apoptosis. Concurrently, venetoclax inhibited Bcl-2 upregulated by either LMP-1 or EBNA-3C. Bort/venetoclax decreased the expression of phosphorylated p65 and Bcl-2 at serine 70 thereby suppressing the NF-κB signaling pathway and promoting apoptosis, respectively. These data corroborated the marked suppression of the growth of xenograft of sLCL in SCID mice (p<0.001). Taken together, the combination of bortezomib and venetoclax targets the pro-survival function of LMP-1 and EBNA-3C of Epstein-Barr virus in spontaneous lymphoblastoid cell lines.

Transformable peptide blocks NF-κB/IκBα pathway through targeted coating IκBα against rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by destructive effects. Although current therapies utilizing antibodies against inflammatory cytokines have shown some success, the inhibition of a single inflammatory molecule may not suffice to impede the progression of RA due to the intricate pathogenesis involving multiple molecules. In this study, we have developed an intelligent transformable peptide, namely BP-FFVLK-DSGLDSM (BFD). BFD has the ability to self-assemble into spherical nanoparticles in water or in the blood circulation to facilitate their delivery and distribution. When endocytosed into immune cells, BFD can identify and attach to phosphorylation sites on IκBα and in situ transform into a nanofibrous network coating NF-κB/IκBα complexes, blocking the phosphorylation and degradation of IκBα. As a result, BFD enables decreasing expression of proinflammatory mediators. In the present study, we demonstrate that BFD exhibits notable efficacy in alleviating arthritis-related manifestations, such as joints and tissues swelling, as well as bone and cartilage destruction on the collagen-induced arthritis (CIA) rat model. The investigation of intracellular biodistribution, phosphorylation of IκBα, and cytokine detection in culture medium supernatant, joint tissue, and serum exhibits strong associations with therapeutic outcomes. The utilization of transformable peptide presents a novel approach for the management of inflammatory diseases.

Oral inoculation of Fusobacterium nucleatum exacerbates ulcerative colitis via the secretion of virulence adhesin FadA

ABSTRACT Fusobacterium nucleatum (F. nucleatum), an anaerobic resident of the oral cavity, is increasingly recognized as a contributing factor to ulcerative colitis (UC). The adhesive properties of F. nucleatum are mediated by its key virulence protein, FadA adhesin. However, further investigations are needed to understand the pathogenic mechanisms of this oral pathogen in UC. The present study aimed to explore the role of the FadA adhesin in the colonization and invasion of oral F. nucleatum in dextran sulphate sodium (DSS)-induced colitis mice via molecular techniques. In this study, we found that oral inoculation of F. nucleatum strain carrying the FadA adhesin further exacerbated DSS-induced colitis, leading to elevated alveolar bone loss, disease severity, and mortality. Additionally, CDH1 gene knockout mice treated with DSS presented increases in body weight and alveolar bone density, as well as a reduction in disease severity. Furthermore, FadA adhesin adhered to its mucosal receptor E-cadherin, leading to the phosphorylation of β-catenin and the degradation of IκBα, the activation of the NF-κB signalling pathway and the upregulation of downstream cytokines. In conclusion, this research revealed that oral inoculation with F. nucleatum facilitates experimental colitis via the secretion of the virulence adhesin FadA. Targeting the oral pathogen F. nucleatum and its virulence factor FadA may represent a promising therapeutic approach for a portion of UC patients.

Kurarinone, a flavonoid from Radix Sophorae Flavescentis, inhibits RANKL-induced osteoclastogenesis in mouse bone marrow-derived monocyte/macrophages.

Inflammation-induced osteoclast proliferation is a crucial contributor to impaired bone metabolism. Kurarinone (KR), a flavonoid extracted from the Radix Sophorae Flavescentis, exhibits notable anti-inflammatory properties. Nevertheless, the precise influence of KR on osteoclast formation remains unclear. This study's objective was to assess the impact of KR on osteoclast activity in vitro and unravel its underlying mechanism. Initially, a target network for KR-osteoclastogenesis-osteoporosis was constructed using network pharmacology. Subsequently, the intersecting targets were identified through the Venny platform and a PPI network was created using Cytoscape 3.9.1. Key targets within the network were identified employing topological algorithms. GO enrichment and KEGG pathway analysis were then performed on these targets to explore their specific functions and pathways. Additionally, molecular docking of potential core targets of KR was conducted, and the results were validated through cell experiments. A total of 83 target genes overlapped between KR and osteoclastogenesis-osteoporosis targets. Enrichment analysis revealed their role in inflammatory response, protein tyrosine kinase activity, osteoclast differentiation, and MAPK and NF-κB signaling pathways. PPI analysis and molecular docking demonstrate that key targets MAPK14 and MAPK8 exhibit more stable binding with KR compared to other proteins. In vitro experiments demonstrate that KR effectively inhibits osteoclast differentiation and bone resorption without cellular toxicity. It suppresses key osteoclast genes (NFATc1, c-Fos, TRAP, MMP9, Ctsk, Atp6v2), hinders IκB-α degradation, and inhibits ERK and JNK phosphorylation, while not affecting p38 phosphorylation. The results indicate that KR may inhibit osteoclast maturation and bone resorption by blocking NF-κB and MAPK signaling pathways, suggesting its potential as a natural therapeutic agent for osteoporosis.

Suppressive effect of isofraxidin on the overexpression of IL-6 and its molecular mechanism in a TPA-treated human hepatocellular carcinoma cell line, HuH-7.

Interleukin-6 (IL-6) is a pleiotropic cytokine that has many biological activities, including inflammation, hematopoiesis, bone metabolism, embryonic development, and other fundamental processes. Recently, IL-6 has been widely recognized as an important pro-inflammatory cytokine involved in cytokine storm pathogenesis during severe inflammatory diseases, such as coronavirus disease 2019 (COVID-19). Therefore, IL-6 is considered to be a therapeutic target for inhibiting cytokine storm. In the present study, we investigated the suppressive effect of isofraxidin, a major coumarin compound of Acanthopanax senticosus, on the overexpression of IL-6 and its molecular mechanism. The expression of IL-6 mRNA was measured using quantitative real-time PCR, and intracellular signaling molecules were detected using western blotting. When the HuH-7 human hepatocellular carcinoma cell line and HepG2 human hepatoblastoma cell line were treated with 12-O-tetradecanoylphorbol 13-acetate (TPA), a marked induction of IL-6 mRNA expression was observed in HuH-7 cells compared with HepG2 cells. Isofraxidin significantly suppressed TPA-induced IL-6 mRNA expression in HuH-7 cells in a dose-dependent manner. Furthermore, isofraxidin inhibited TPA-induced phosphorylation of ERK1/2 in a dose-dependent manner. Similarly, the MAPK/ERK inhibitor U0126 suppressed TPA-induced IL-6 mRNA expression. However, isofraxidin had no effects on TPA-induced phosphorylation of SAPK/JNK, Akt (Ser473), and STAT3 (Tyr705), nuclear translocation of NF-κB p65, and degradation of IκB. Taken together, isofraxidin suppresses TPA-induced overexpression of IL-6 mRNA by selectively inhibiting the activation of the MAPK/ERK pathway in HuH-7 cells, indicating that isofraxidin may be an effective anti-inflammatory agent for treating cytokine storm.

NrCAM activates the NF-κB signalling pathway by competitively binding to SUMO-1 and promotes Th17 cell differentiation in Graves' disease.

This study aimed to explore the molecular mechanism of neuronal cell adhesion molecule (NrCAM) by regulating Th17 cell differentiation in the pathogenesis of Graves' disease (GD). Naïve CD4+ T cells were isolated from peripheral blood mononuclear cells of GD patients and healthy control (HC) subjects. During the differentiation of CD4+ T cells into Th17 cells, NrCAM level in GD group was improved. Interference with NrCAM in CD4+ T cells of GD patients decreased the percentage of Th17 cells. NrCAM overexpression in CD4+ T cells of HC subjects increased the percentage of Th17 cells and upregulated p-IκBα, p50, p65, c-Rel protein expressions, and NF-κB inhibitor BAY11-7082 partially reversed NrCAM effect. NrCAM overexpression promoted the degradation of IκBα, and overexpression of small ubiquitin-related modifier 1 (SUMO-1) inhibited IκBα degradation. NrCAM overexpression reduced IκBα binding to SUMO-1. During Th17 cell differentiation in HC group, NrCAM overexpression increased IL-21 levels and secretion, and IL-21 neutralizing antibody reversed this effect. IL-21 level was decreased after p65 interference in CD4+ T cells of HC subjects. p65 interacts with IL-21 promoter region. In conclusion, NrCAM binds to SUMO-1 and increases phosphorylation of IκBα, leading to activation of NF-κB pathway, which promotes Th17 cell differentiation.

Protective Effect of Hibifolin on Lipopolysaccharide-Induced Acute Lung Injury Through Akt Phosphorylation and NFκB Pathway.

Acute lung injury (ALI) is a difficult condition to manage, especially when it is complicated by bacterial sepsis. Hibifolin, a flavonoid glycoside, has anti-inflammatory properties that make it a potential treatment for ALI. However, more research is needed to determine its effectiveness in LPS-induced ALI. In this study, male ICR mice were treated with hibifolin before LPS-induced ALI. Protein content and neutrophil count in bronchoalveolar lavage (BAL) fluid were measured by BCA assay and Giemsa staining method, respectively. The levels of proinflammatory cytokines and adhesive molecules were detected by ELISA assay. The expression of NFκB p65 phosphorylation, IκB degradation, and Akt phosphorylation was assessed by western blot assay. Hibifolin pre-treatment significantly reduced pulmonary vascular barrier dysfunction and neutrophil infiltration into the BAL fluid in LPS-induced ALI mice. In addition, LPS-induced expression of proinflammatory cytokines (IL-1β, IL-6, TNF-α) and adhesive molecules (ICAM-1, VCAM-1) within the BAL fluid were markedly reduced by hibifolin in LPS-induced ALI mice. More, hibifolin inhibited LPS-induced phosphorylation of NFκB p65, degradation of IκB, and phosphorylation of Akt in lungs with ALI mice. In conclusion, hibifolin shows promise in improving the pathophysiological features and proinflammatory responses of LPS-induced ALI in mice through the NFκB pathway and its upstream factor, Akt phosphorylation.

Eugenol: A Potential Modulator of Human Platelet Activation and Mouse Mesenteric Vascular Thrombosis via an Innovative cPLA2-NF-κB Signaling Axis.

Platelets, a type of anucleated cell, play a crucial role in cardiovascular diseases (CVDs). Therefore, targeting platelet activation is essential for mitigating CVDs. Endogenous agonists, such as collagen, activate platelets by initiating signal transduction through specific platelet receptors, leading to platelet aggregation. Eugenol, primarily sourced from clove oil, is known for its antibacterial, anticancer, and anti-inflammatory properties, making it a valuable medicinal agent. In our previous study, eugenol was shown to inhibit platelet aggregation induced by collagen and arachidonic acid. We concluded that eugenol exerts a potent inhibitory effect on platelet activation by targeting the PLCγ2-PKC and cPLA2-TxA2 pathways, thereby suppressing platelet aggregation. In our current study, we found that eugenol significantly inhibits NF-κB activation. This led us to investigate the relationship between the NF-κB and cPLA2 pathways to elucidate how eugenol suppresses platelet activation. In this study, we prepared platelet suspensions from the blood of healthy human donors to evaluate the inhibitory mechanisms of eugenol on platelet activation. We utilized immunoblotting and confocal microscopy to analyze these mechanisms in detail. Additionally, we assessed the anti-thrombotic effect of eugenol by observing fluorescein-induced platelet plug formation in the mesenteric microvessels of mice. For immunoblotting and confocal microscopy studies, eugenol significantly inhibited NF-κB-mediated signaling events stimulated by collagen in human platelets. Specifically, it reduced the phosphorylation of IKK and p65 and prevented the degradation of IκBα. Additionally, CAY10502, a cPLA2 inhibitor, significantly reduced NF-κB-mediated signaling events. In contrast, BAY11-7082, an IKK inhibitor, did not affect collagen-stimulated cPLA2 phosphorylation. These findings suggest that cPLA2 acts as an upstream regulator of NF-κB activation during platelet activation. Furthermore, both BAY11-7082 and CAY10502 significantly reduced the collagen-induced rise in intracellular calcium levels. In the animal study, eugenol demonstrated potential as an anti-thrombotic agent by significantly reducing platelet plug formation in fluorescein-irradiated mouse mesenteric microvessels. Our study uncovered a novel pathway in platelet activation involving the cPLA2-NF-κB axis, which plays a key role in the antiplatelet effects of eugenol. These findings suggest that eugenol could serve as a valuable and potent prophylactic or therapeutic option for arterial thrombosis.

Ferritin Light Chain Alleviates Cerebral Ischemic-Reperfusion Injury-Induced Neuroinflammation via the HIF1α Mediated NF-κB Signaling Pathways.

Ferritin light chain (FtL) is a complex formed by apoferritin and iron core and is one of the main storage forms of iron. Currently, the precise role of FtL in cerebral ischemia/reperfusion injury (CIRI) remains undetermined. This investigation aimed to elucidate the roles and underlying mechanisms of FtL in CIRI. To induce CIRI, an oxygen-glucose deprivation (OGD) model in microglia and middle cerebral artery occlusion (MCAO) model were established using C57BL/6J mice. The in vivo and in vitro FtL expression patterns were assessed. Furthermore, the potential regulatory mechanism of FtL at the upstream level was also explored. In addition, the in vivo and in vitro role of FtL in post-ischemic inflammation was also clarified. The results indicated that FtL was up-regulated in OGD-induced microglia and CIRI mice. Moreover, OGD activated HIF1α, which interacted with the FtL promoter region as an activator, thereby increasing FtL expression. Furthermore, FtL attenuated the release of pro-inflammatory cytokines (TNFα, IL6) and decreased levels of COX2 and iNOS in microglia; however, FtL knockdown had the opposite effects. Up-regulated FtL was observed to inhibit OGD-induced NF-κB activation in microglia, decreased IκBα degradation, and reduced NF-κB/p65 nuclear translocation. In summary, this study revealed an underlying mechanism of FtL upregulation via HIF1α and highlighted its protective role against post-ischemic neuroinflammation, indicating the potential of FtL as a target for CIRI treatment.

MG132 dramatically reduces SAA expression in chicken hepatocellular carcinoma cells at the transcript level independent of its endogenous promoter

BackgroundMG132, a proteasome inhibitor, is widely used to inhibit nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activity by proteasome-mediated degradation of IκB. It has been marketed as a specific, reversible, cell-permeable and low-cost inhibitor. However, adverse effects of the compound have been reported in the literature. We recently discovered and characterised a point mutation in the acute phase protein serum amyloid A (SAA) in chickens, by overexpressing the protein in chicken hepatocellular carcinoma (LMH) cells. This serine to arginine exchange at amino acid position 90 (SAA.R90S) leads to intra- and extracellular accumulation of SAA, which is surprisingly counteracted by MG132 treatment, independent of SAA’s intrinsic promoter.Methods and ResultsTo test, whether low proteasomal degradation of SAA.R90S is responsible for the observed intra- and extracellular SAA accumulation, we intended to inhibit the proteasome in SAA wild type (SAA.WT) overexpressing cells with MG132. However, we observed an unexpected drastic decrease in SAA protein expression at the transcript level. NF-κB gene expression was unchanged by MG132 at the measured time point.ConclusionsThe observed results demonstrate that MG132 inhibits SAA expression at the transcript level, independent of its endogenous promoter. Further, the data might indicate that NF-κB is not involved in the observed MG132-induced inhibition of SAA expression. We, consequently, question in this brief report whether MG132 should truly be categorised as a specific ubiquitin proteasome inhibitor and recommend the usage of alternative compounds.

Scutellarein Suppresses the Production of ROS and Inflammatory Mediators of LPS-Activated Bronchial Epithelial Cells and Attenuates Acute Lung Injury in Mice.

Scutellarein is a key active constituent present in many plants, especially in Scutellaria baicalensis Georgi and Erigeron breviscapus (vant.) Hand-Mazz which possesses both anti-inflammatory and anti-oxidative activities. It also is the metabolite of scutellarin, with the ability to relieve LPS-induced acute lung injury (ALI), strongly suggesting that scutellarein could suppress respiratory inflammation. The present study aimed to investigate the effects of scutellarein on lung inflammation by using LPS-activated BEAS-2B cells (a human bronchial epithelial cell line) and LPS-induced ALI mice. The results showed that scutellarein could reduce intracellular reactive oxygen species (ROS) accumulation through inhibiting the activation of NADPH oxidases, markedly downregulating the transcription and translation of pro-inflammatory cytokines, including interleukin-6 (IL-6), C-C motif chemokine ligand 2 (CCL2), and C-X-C motif chemokine ligand (CXCL) 8 in LPS-activated BEAS-2B cells. The mechanism study revealed that it suppressed the phosphorylation and degradation of IκBα, consequently hindering the translocation of p65 from the cytoplasm to the nucleus and its subsequent binding to DNA, thereby decreasing NF-κB-regulated gene transcription. Notably, scutellarein had no impact on the activation of AP-1 signaling. In LPS-induced ALI mice, scutellarein significantly decreased IL-6, CCL2, and tumor necrosis factor-α (TNF-α) levels in the bronchoalveolar lavage fluid, attenuated lung injury, and inhibited neutrophil infiltration. Our findings suggest that scutellarein may be a beneficial agent for the treatment of infectious pneumonia by virtue of its anti-oxidative and anti-inflammatory activities.

Key features of the innate immune response is mediated by the immunoproteasome in microglia.

Microglia are the resident immune cells of the central nervous system (CNS). We and others have shown that the inflammatory response of microglia is partially regulated by the immunoproteasome, an inducible form of the proteasome responsible for the generation of major histocompatibility complex (MHC) class I epitopes. While the role of the proteasome in the adaptive immune system is well established, emerging evidence suggests the immunoproteasome may have discrete functions in the innate immune response. Here, we show that inhibiting the immunoproteasome reduces the IFNγ-dependent induction of complement activator C1q, suppresses phagocytosis, and alters the cytokine expression profile in a microglial cell line and microglia derived from human inducible pluripotent stem cells. Moreover, we show that the immunoproteasome regulates the degradation of IκBα, a modulator of NF-κB signaling. Finally, we demonstrate that NADH prevents induction of the immunoproteasome, representing a potential pathway to suppress immunoproteasome-dependent immune responses.

Protective effects of piperlongumine against adjuvant-induced arthritis in rats through modulating OPG/RANKL/NF-κB signaling pathway.

We examined the antirheumatoid effects of piperlongumine (PLM) on rat adjuvant-induced arthritis (AIA) and explored the underlying mechanisms involved. PLM (2.5, 5, and 10 mg/kg) was administered intraperitoneally to AIA rats to assess its effectiveness. Blood, thymus, spleen, ankle joint, and synovial tissue samples were gathered for subsequent analyses, like enzyme-linked immunosorbent assay, thymus/spleen index measurement, ankle joint pathological examination, immunohistochemistry assay, polymerase chain reaction, and western blot assay. Moreover, the involvement of osteoprotegerin (OPG)/receptor activators of nuclear factor κB ligand (RANKL)/nuclear factor-κB (NF-κB) signaling was investigated. PLM effectively relieved inflammation and joint destruction in AIA rats, as indicated by reductions in hind paw swelling, arthritis index, thymus/spleen index, ankle joint pathological damage, production of TNF-α, IL-1β, and IL-6 in both serum and synovium, and osteoclast formation. Also, PLM treatment raised OPG production, reduced RANKL expression, and elevated the OPG/RANKL ratio in synovial tissues. Furthermore, PLM prevented IκBα degradation and phosphorylation, resulting in a reduced expression of the nuclear NF-κB p65 protein in AIA rat synovial tissues. PLM demonstrated strong antiarthritic effects in rats with AIA by influencing the OPG/RANKL/NF-κB signaling pathway, highlighting its potential clinical relevance in treating rheumatoid arthritis.