NF-κB p65 dimerization and DNA-binding is important for inflammatory gene expression

Pharmacological insights and role of bufalin (bufadienolides) in inflammation modulation: a narrative review

Bufadienolides, specifically bufalin, have garnered attention for their potential therapeutic application in modulating inflammatory pathways. Bufalin is derived from toad venom and exhibits promising anti-inflammatory properties. Its anti-inflammatory effects have been demonstrated by influencing crucial signaling pathways like NF-B, MAPK, and JAK-STAT, resulting in the inhibition of pro-inflammatory substances like cytokines, chemokines, and adhesion molecules. Bufalin blocks inflammasome activation and reduces oxidative stress, hence increasing its anti-inflammatory properties. Bufalin has shown effectiveness in reducing inflammation-related diseases such as cancer, cardiovascular problems, and autoimmune ailments in preclinical investigations. Furthermore, producing new approaches of medication delivery and combining therapies with bufalin shows potential for improving its effectiveness and reducing adverse effects. This review explores the pharmacological effects and mechanistic approaches of bufalin as an anti-inflammatory agent, which further highlights its potential for therapy and offers the basis for further study on its therapeutic application in inflammation-related disorders.

Molecular signatures of astrocytes and microglia maladaptive responses to acute stress are rescued by a single administration of ketamine in a rodent model of PTSD

Stress affects the brain and alters its neuroarchitecture and function; these changes can be severe and lead to psychiatric disorders. Recent evidence suggests that astrocytes and microglia play an essential role in the stress response by contributing to the maintenance of cerebral homeostasis. These cells respond rapidly to all stimuli that reach the brain, including stressors. Here, we used a recently validated rodent model of post-traumatic stress disorder in which rats can be categorized as resilient or vulnerable after acute inescapable footshock stress. We then investigated the functional, molecular, and morphological determinants of stress resilience and vulnerability in the prefrontal cortex, focusing on glial and neuronal cells. In addition, we examined the effects of a single subanesthetic dose of ketamine, a fast-acting antidepressant recently approved for the treatment of resistant depression and proposed for other stress-related psychiatric disorders. The present results suggest a prompt glial cell response and activation of the NF-κB pathway after acute stress, leading to an increase in specific cytokines such as IL-18 and TNF-α. This response persists in vulnerable individuals and is accompanied by a significant change in the levels of critical glial proteins such as S100B, CD11b, and CX43, brain trophic factors such as BDNF and FGF2, and proteins related to dendritic arborization and synaptic architecture such as MAP2 and PSD95. Administration of ketamine 24 h after the acute stress event rescued many of the changes observed in vulnerable rats, possibly contributing to support brain homeostasis. Overall, our results suggest that pivotal events, including reactive astrogliosis, changes in brain trophic factors, and neuronal damage are critical determinants of vulnerability to acute traumatic stress and confirm the therapeutic effect of acute ketamine against the development of stress-related psychiatric disorders.

In silico screening of phytoconstituents as potential anti-inflammatory agents targeting NF-κB p65: an approach to promote burn wound healing

Chronic burn wounds are frequently characterised by a prolonged and dysregulated inflammatory phase that is mediated by over-activation of NF-κB p65. Synthetic wound healing drugs used for treatment of inflammation are primarily associated with several shortcomings which reduce their therapeutic index. In this scenario, phytoconstituents that exhibit multifaceted biological activities including anti-inflammatory effects have emerged as a promising therapeutic alternative. However, identification and isolation of phytoconstituents from medicinal herbs is a cumbersome method that is linked to profound uncertainty. Hence, present study aimed to identify prospective phytoconstituents as inhibitors of RHD of NF-κB p65 by utilizing in silico approach. Virtual screening of 2821 phytoconstituents was performed against protein model. Out of 2821 phytoconstituents, 162 phytoconstituents displayed a higher binding affinity (≤ -8.0 kcal/mol). These 162 phytoconstituents were subjected to ADMET predictions, and 15 of them were found to satisfy Lipinski's rule of five and showed favorable pharmacokinetic properties. Among these 15 phytoconstituents, 5 phytoconstituents with high docking scores i.e. silibinin, bismurrayaquinone A, withafastuosin B, yuccagenin, (+)-catechin 3-gallate were selected for molecular dynamics (MD) simulation analysis. Results of MD simulation indicated that withafastuosin B, (+)-catechin 3-gallate and yuccagenin produced a compact and stable complex with protein without significant variations in conformation. Relative binding energy analysis of best hit molecules indicate that withafastuosin B, and (+)-catechin 3-gallate exhibit high binding affinity with target protein among other lead molecules. Findings of study suggest that these phytoconstituents could serve as promising anti-inflammatory agents for treatment of burn wounds by inhibiting the RHD of NF-κB p65.Communicated by Ramaswamy H. Sarma.

Sarcococca saligna fabricated gold nanoparticles alleviated in vitro oxidative stress and inflammation in human adipose-derived stem cells

Oxidative stress is a destructive phenomenon that affects various cell structures including membranes, proteins, lipoproteins, lipids, and DNA. Oxidative stress and inflammation owing to lifestyle changes may lead to serious diseases such as Cancers, Gout, and Arthritis etc. These disorders can be prevented using different therapeutic strategies including nanomedicine. Biosynthesized gold nanoparticles (GNPs) because of their anti-inflammatory and antioxidant bioactivities can be key player in reversal of these ailments. This study was carried out to evaluate the anti-inflammatory and antioxidant potential of bio fabricated GNPs with Sarcococca saligna (S. saligna) extract on injured human adipose-derived Mesenchymal stem cells (hADMSCs). GNPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, Scanning Electron Microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and energy dispersive x-ray (EDS). Phytochemical screening of biosynthesized GNPs exhibited a significant release of polyphenols, that is, total phenolic content (TPC) and total flavonoid content (TFC). GNPs priming amended the in vitro injury caused by Monosodium Iodoacetate (MIA) as exhibited by improved cell viability, wound closure response and superoxide dismutase activity (SOD). The anti-inflammatory conduct assessed through NF-κB pathway and other associated inflammatory markers reported down-regulation of TNF-α (0.644 ± 0.045), IL-1β (0.694 ± 0.147) and IL-6 (0.622 ± 0.112), apoptosis causing genes like Caspase-3 (0.734 ± 0.13) and BAX (0.830 ± 0.12), NF-κB pathway, p65 (0.672 ± 0.084) and p105 (0.539 ± 0.083) associated genes. High SOD activity (95 ± 5.25%) revealed by treated hADMSCs with GNPs also supported the antioxidant role of GNPs in vitro model. This study concludes that S. saligna bio fabricated GNPs priming may improve the therapeutic potential of hADMSCs against chronic inflammatory problems by regulating NF-κB pathway.

Alcohol-induced liver injury in signalling pathways and curcumin's therapeutic potential

Confronting the profound public health concern of alcohol-induced liver damage calls for inventive therapeutic measures. The social, economic, and clinical ramifications are extensive and demand a comprehensive understanding. This thorough examination uncovers the complex relationship between alcohol intake and liver damage, with a special emphasis on the pivotal roles of the Toll-like receptor 4 (TLR4)/NF-κB p65 and CYP2E1/ROS/Nrf2 signalling networks. Different alcohol consumption patterns, determined by a myriad of factors, have significant implications for liver health, leading to a spectrum of adverse effects. The TLR4/NF-κB p65 pathway, a principal regulator of inflammation and immune responses, significantly contributes to various disease states when its balance is disrupted. Notably, the TLR4/MD-2-TNF-α pathway has been linked to non-alcohol related liver disease, while NF-κB activation is associated with alcohol-induced liver disease (ALD). The p65 subunit of NF-κB, primarily responsible for the release of inflammatory cytokines, hastens the progression of ALD. Breakthrough insights suggest that curcumin, a robust antioxidant and anti-inflammatory compound sourced from turmeric, effectively disrupts the TLR4/NF-κB p65 pathway. This heralds a new approach to managing alcohol-induced liver damage. Initial clinical trials support curcumin's therapeutic potential, highlighting its ability to substantially reduce liver enzyme levels. The narrative surrounding alcohol-related liver injury is gradually becoming more intricate, intertwining complex signalling networks such as TLR4/NF-κB p65 and CYP2E1/ROS/Nrf2. The protective role of curcumin against alcohol-related liver damage marks the dawn of new treatment possibilities. However, the full realisation of this promising therapeutic potential necessitates rigorous future research to definitively understand these complex mechanisms and establish curcumin's effectiveness and safety in managing alcohol-related liver disorders.

Modified Curcuminoid-Rich Extract Liposomal CRE-SDInhibits Osteoclastogenesis via the Canonical NF-κB Signaling Pathway

Curcuminoids, namely curcumin, demethoxycurcumin, and bisdemethoxycurcumin, are the major active compounds found in Curcuma longa L. (turmeric). Although their suppressive effects on bone resorption have been demonstrated, their pharmacokinetic disadvantages remain a concern. Herein, we utilized solid dispersion of a curcuminoid-rich extract (CRE), comprising such curcuminoids, to prepare CRE-SD; subsequently, we performed liposome encapsulation of the CRE-SD to yield liposomal CRE-SD. In vitro release assessment revealed that a lower cumulative mass percentage of CRE-SD was released from liposomal CRE-SD than from CRE-SD samples. After culture of murine RANKL-stimulated RAW 264.7 macrophages, our in vitro examinations confirmed that liposomal CRE-SD may impede osteoclastogenesis by suppressing p65 and IκBα phosphorylation, together with nuclear translocation and transcriptional activity of phosphorylated p65. Blind docking simulations showed the high binding affinity between curcuminoids and the IκBα/p50/p65 protein complex, along with many intermolecular interactions, which corroborated our in vitro findings. Therefore, liposomal CRE-SD can inhibit osteoclastogenesis via the canonical NF-κB signaling pathway, suggesting its pharmacological potential for treating bone diseases with excessive osteoclastogenesis.

Circular RNA Tmcc1 improves astrocytic glutamate metabolism and spatial memory via NF-κB and CREB signaling in a bile duct ligation mouse model: transcriptional and cellular analyses

BACKGROUND

Hepatic encephalopathy-induced hyperammonemia alters astrocytic glutamate metabolism in the brain, which is involved in cognitive decline. To identify specific therapeutic strategies for the treatment of hepatic encephalopathy, various molecular signaling studies, such as non-coding RNA functional study, have been conducted. However, despite several reports of circular RNAs (circRNAs) in the brain, few studies of circRNAs in hepatic encephalopathy-induced neuropathophysiological diseases have been conducted.

METHODS

In this study, we performed RNA sequencing to identify whether the candidate circRNA cirTmcc1 is specifically expressed in the brain cortex in a bile duct ligation (BDL) mouse model of hepatic encephalopathy.

RESULTS

Based on transcriptional and cellular analysis, we investigated the circTmcc1-dysregulation-induced changes in the expression of several genes that are associated with intracellular metabolism and astrocyte function. We found that the circTmcc1 binds with the NF-κB p65-CREB transcriptional complex and regulates the expression of the astrocyte transporter EAAT2. Furthermore, circTmcc1 contributed to the secretion of proinflammatory mediators and glutamate metabolism in astrocytes and subsequently modulated an improvement in spatial memory by mediating neuronal synaptic plasticity.

CONCLUSIONS

Thus, circTmcc1 may be a promising circRNA candidate for targeted interventions to prevent and treat the neuropathophysiological complications that occur due to hepatic encephalopathy.

MALT1 paracaspase is overexpressed in hepatocellular carcinoma and promotes cancer cell survival and growth

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and the third leading cause of cancer-related deaths worldwide. Despite recent advances in treatment options, therapeutic management of HCC remains a challenge, emphasizing the importance of exploring novel targets. MALT1 paracaspase is a druggable signaling molecule whose dysregulation has been linked to hematological and solid tumors. However, the role of MALT1 in HCC remains poorly understood, leaving its molecular functions and oncogenic implications unclear. Here we provide evidence that MALT1 expression is elevated in human HCC tumors and cell lines, and that correlates with tumor grade and differentiation state, respectively. Our results indicate that ectopic expression of MALT1 confers increased cell proliferation, 2D clonogenic growth, and 3D spheroid formation in well differentiated HCC cell lines with relatively low MALT1 levels. In contrast, stable silencing of endogenous MALT1 through RNA interference attenuates these aggressive cancer cell phenotypes, as well as migration, invasion, and tumor-forming ability, in poorly differentiated HCC cell lines with higher paracaspase expression. Consistently, we find that pharmacological inhibition of MALT1 proteolytic activity with MI-2 recapitulates MALT1 depletion phenotypes. Finally, we show that MALT1 expression is positively correlated with NF-kB activation in human HCC tissues and cell lines, suggesting that its tumor promoting functions may involve functional interaction with the NF-kB signaling pathway. This work unveils new insights into the molecular implications of MALT1 in hepatocarcinogenesis and places this paracaspase as a potential marker and druggable liability in HCC.

Interleukin-1β triggers matrix metalloprotease-3 expression through p65/RelA activation in melanoma cells

Melanoma shows highly aggressive behavior (i.e., local invasion and metastasis). Matrix metalloprotease-3 (MMP-3), a zinc-dependent endopeptidase, degrades several extracellular substrates and contributes to local invasion by creating a microenvironment suitable for tumor development. Here, we report that interleukin-1β (IL-1β) triggers the MMP-3 expression in canine melanoma cells. The activity of MMP-3 in the culture supernatant was increased in IL-1β-treated melanoma cells. IL-1β time- and dose-dependently provoked the mRNA expression of MMP-3. IL-1β induced the migration of melanoma cells; however, this migration was attenuated by UK356618, an MMP-3 inhibitor. When the cells were treated with the nuclear factor-κB (NF-κB) inhibitor TPCA-1, the inhibition of MMP-3 expression was observed. In IL-1β-treated cells, the phosphorylation both of p65/RelA and p105 was detected, indicating NF-κB pathway activation. In p65/RelA-depleted melanoma cells, IL-1β-mediated mRNA expression of MMP-3 was inhibited, whereas this reduction was not observed in p105-depleted cells. These findings suggest that MMP-3 expression in melanoma cells is regulated through IL-1β-mediated p65/RelA activation, which is involved in melanoma cell migration.

Epigenomic and transcriptomic analyses reveal differences between low-grade inflammation and severe exhaustion in LPS-challenged murine monocytes

Emerging studies suggest that monocytes can be trained by bacterial endotoxin to adopt distinct memory states ranging from low-grade inflammation to immune exhaustion. While low-grade inflammation may contribute to the pathogenesis of chronic diseases, exhausted monocytes with pathogenic and immune-suppressive characteristics may underlie the pathogenesis of polymicrobial sepsis including COVID-19. However, detailed processes by which the dynamic adaption of monocytes occur remain poorly understood. Here we exposed murine bone-marrow derived monocytes to chronic lipopolysaccharide (LPS) stimulation at low-dose or high-dose, as well as a PBS control. The cells were profiled for genome-wide H3K27ac modification and gene expression. The gene expression of TRAM-deficient and IRAK-M-deficient monocytes with LPS exposure was also analyzed. We discover that low-grade inflammation preferentially utilizes the TRAM-dependent pathway of TLR4 signaling, and induces the expression of interferon response genes. In contrast, high dose LPS uniquely upregulates exhaustion signatures with metabolic and proliferative pathways. The extensive differences in the epigenomic landscape between low-dose and high-dose conditions suggest the importance of epigenetic regulations in driving differential responses. Our data provide potential targets for future mechanistic or therapeutic studies.

[Mechanisms of age-related changes in the morphology of the pulp system of the first lower molars]

OBJECTIVE

To study the coupling of age-related systemic changes in inflammation-mediated apoptosis with the features of the anatomy of the pulp system of the first mandibular molars in patients with chronic pulpitis and periodontitis.

MATERIAL AND METHODS

The study included 55 patients of both sexes from 18 to 75 years of age in three age groups - young (18-44 years) (n=17), middle (45-59 years) (n=18), elderly (60-74 years) (n=20) with indications for endodontic treatment. Diagnostic measures were supplemented with New Tom 3G cone-beam tomography. The concentration of anitapoptotic protein Bcl-XL and tumor necrosis factor-a (TNF-a) was determined in the blood, and the level of the nuclear transcription factor NF-KB subunit p65 was determined in the lysates of mononuclear cells.

RESULTS

As a result of the analysis of the sections, significant obliteration of the pulp was revealed throughout and an increase in the frequency of occurrence of slit-shaped channels in the distal root of the first molar of the mandible in elderly patients.

CONCLUSION

The pathogenetic factors leading to a change in the morphology of the pulp system include old age and an imbalance in the system of anti-inflammatory cytokine transcription mechanisms, which contributes to increased apoptosis and the protracted nature of inflammation.

Monitoring the Levels of Cellular NF-κB Activation States

The NF-κB signaling system plays an important regulatory role in the control of many biological processes. The activities of NF-κB signaling networks and the expression of their target genes are frequently elevated in pathophysiological situations including inflammation, infection, and cancer. In these conditions, the outcome of NF-κB activity can vary according to (i) differential activation states, (ii) the pattern of genomic recruitment of the NF-κB subunits, and (iii) cellular heterogeneity. Additionally, the cytosolic NF-κB activation steps leading to the liberation of DNA-binding dimers need to be distinguished from the less understood nuclear pathways that are ultimately responsible for NF-κB target gene specificity. This raises the need to more precisely determine the NF-κB activation status not only for the purpose of basic research, but also in (future) clinical applications. Here we review a compendium of different methods that have been developed to assess the NF-κB activation status in vitro and in vivo. We also discuss recent advances that allow the assessment of several NF-κB features simultaneously at the single cell level.

Evaluation of Gallic Acid-Coated Gold Nanoparticles as an Anti-Aging Ingredient

Hyperglycemic environment-induced oxidative stress-mediated matrix metalloproteinase-1 (MMP-1) plays a crucial role in the degradation of the extracellular matrix (ECM), which might contribute to premature skin aging. Synthesized, environmentally friendly gallic acid-coated gold nanoparticles (GA–AuNPs) have been evaluated as an anti-aging antioxidant. Their microstructure was characterized by transmission electron microscopy (TEM), which showed that GA–AuNPs are spherical when prepared at pH 11. Dynamic light scattering (DLS) analysis revealed that the average hydrodynamic diameter of a GA–AuNP is approximately 40 nm and with a zeta potential of −49.63 ± 2.11 mV. Additionally, the present data showed that GA–AuNPs have a superior ability to inhibit high glucose-mediated MMP-1-elicited type I collagen degradation in dermal fibroblast cells. Collectively, our data indicated that high-glucose-mediated ROS production was reduced upon cell treatment with GA–AuNPs, which blocked p38 MAPK/ERK-mediated c-Jun, c-Fos, ATF-2 phosphorylation, and the phosphorylation of NFκB, leading to the down-regulation of MMP-1 mRNA and protein expression in high glucose-treated cells. Our findings suggest that GA-AuNPs have a superior ability to inhibit high-glucose-mediated MMP-1-elicited ECM degradation, which highlights its potential as an anti-aging ingredient.

The hepatocyte IKK:NF-κB axis promotes liver steatosis by stimulating de novo lipogenesis and cholesterol synthesis

OBJECTIVE

Obesity-related chronic inflammation plays an important role in the development of Metabolic Associated Fatty Liver Disease (MAFLD). Although the contribution of the pro-inflammatory NF-κB signaling pathway to the progression from simple steatosis to non-alcoholic steatohepatitis (NASH) is well-established, its role as an initiator of hepatic steatosis and the underlying mechanism remains unclear. Here, we investigated the hypothesis that the hepatocytic NF-κB signaling pathway acts as a metabolic regulator, thereby promoting hepatic steatosis development.

METHODS

A murine model expressing a constitutively active form of IKKβ in hepatocytes (Hep-IKKβca) was used to activate hepatocyte NF-κB. In addition, IKKβca was also expressed in hepatocyte A20-deficient mice (IKKβca;A20^LKO). A20 is an NF-κB-target gene that inhibits the activation of the NF-κB signaling pathway upstream of IKKβ. These mouse models were fed a sucrose-rich diet for 8 weeks. Hepatic lipid levels were measured and using [1-¹³C]-acetate de novo lipogenesis and cholesterol synthesis rate were determined. Gene expression analyses and immunoblotting were used to study the lipogenesis and cholesterol synthesis pathways.

RESULTS

Hepatocytic NF-κB activation by expressing IKKβca in hepatocytes resulted in hepatic steatosis without inflammation. Ablation of hepatocyte A20 in Hep-IKKβca mice (IKKβca;A20^LKO mice) exacerbated hepatic steatosis, characterized by macrovesicular accumulation of triglycerides and cholesterol, and increased plasma cholesterol levels. Both De novo lipogenesis (DNL) and cholesterol synthesis were found elevated in IKKβca;A20^LKO mice. Phosphorylation of AMP-activated kinase (AMPK) - a suppressor in lipogenesis and cholesterol synthesis - was decreased in IKKβca;A20^LKO mice. This was paralleled by elevated protein levels of hydroxymethylglutaryl-CoA synthase 1 (HMGCS1) and reduced phosphorylation of HMG-CoA reductase (HMGCR) both key enzymes in the cholesterol synthesis pathway. Whereas inflammation was not observed in young IKKβca;A20^LKO mice sustained hepatic NF-κB activation resulted in liver inflammation, together with elevated hepatic and plasma cholesterol levels in middle-aged mice.

CONCLUSIONS

The hepatocytic IKK:NF-κB axis is a metabolic regulator by controlling DNL and cholesterol synthesis, independent of its central role in inflammation. The IKK:NF-κB axis controls the phosphorylation levels of AMPK and HMGCR and the protein levels of HMGCS1. Chronic IKK-mediated NF-κB activation may contribute to the initiation of hepatic steatosis and cardiovascular disease risk in MAFLD patients.

Tumor necrosis factor-induced ArhGEF10 selectively activates RhoB contributing to human microvascular endothelial cell tight junction disruption

Capillary endothelial cells (ECs) maintain a semi-permeable barrier between the blood and tissue by forming inter-EC tight junctions (TJs), regulating selective transport of fluid and solutes. Overwhelming inflammation, as occurs in sepsis, disrupts these TJs, leading to leakage of fluid, proteins, and small molecules into the tissues. Mechanistically, disruption of capillary barrier function is mediated by small Rho-GTPases, such as RhoA, -B, and -C, which are activated by guanine nucleotide exchange factors (GEFs) and disrupted by GTPase-activating factors (GAPs). We previously reported that a mutation in a specific RhoB GAP (p190BRhoGAP) underlays a hereditary capillary leak syndrome. Tumor necrosis factor (TNF) treatment disrupts TJs in cultured human microvascular ECs, a model of capillary leak. This response requires new gene transcription and involves increased RhoB activation. However, the specific GEF that activates RhoB in capillary ECs remains unknown. Transcriptional profiling of cultured tight junction-forming human dermal microvascular endothelial cells (HDMECs) revealed that 17 GEFs were significantly induced by TNF. The function of each candidate GEF was assessed by short interfering RNA depletion and trans-endothelial electrical resistance screening. Knockown of ArhGEF10 reduced the TNF-induced loss of barrier which was phenocopied by RhoB or dual ArhGEF10/RhoB knockdown. ArhGEF10 knockdown also reduced the extent of TNF-induced RhoB activation and disruption at tight junctions. In a cell-free assay, immunoisolated ArhGEF10 selectively catalyzed nucleotide exchange to activate RhoB, but not RhoA or RhoC. We conclude ArhGEF10 is a TNF-induced RhoB-selective GEF that mediates TJ disruption and barrier loss in human capillary endothelial cells.

Challenges with Methods for Detecting and Studying the Transcription Factor Nuclear Factor Kappa B (NF-κB) in the Central Nervous System

The transcription factor nuclear factor kappa B (NF-κB) is highly expressed in almost all types of cells. NF-κB is involved in many complex biological processes, in particular in immunity. The activation of the NF-κB signaling pathways is also associated with cancer, diabetes, neurological disorders and even memory. Hence, NF-κB is a central factor for understanding not only fundamental biological presence but also pathogenesis, and has been the subject of intense study in these contexts. Under healthy physiological conditions, the NF-κB pathway promotes synapse growth and synaptic plasticity in neurons, while in glia, NF-κB signaling can promote pro-inflammatory responses to injury. In addition, NF-κB promotes the maintenance and maturation of B cells regulating gene expression in a majority of diverse signaling pathways. Given this, the protein plays a predominant role in activating the mammalian immune system, where NF-κB-regulated gene expression targets processes of inflammation and host defense. Thus, an understanding of the methodological issues around its detection for localization, quantification, and mechanistic insights should have a broad interest across the molecular neuroscience community. In this review, we summarize the available methods for the proper detection and analysis of NF-κB among various brain tissues, cell types, and subcellular compartments, using both qualitative and quantitative methods. We also summarize the flexibility and performance of these experimental methods for the detection of the protein, accurate quantification in different samples, and the experimental challenges in this regard, as well as suggestions to overcome common challenges.

Herpes Simplex Virus Type 2 Glycoprotein D Inhibits NF-κB Activation by Interacting with p65

NF-κB plays a crucial role in regulating cell proliferation, inflammation, apoptosis, and immune responses. HSV type 2 (HSV-2) is one of the most predominant sexually transmitted pathogens worldwide, and its infection increases the risk of HIV type 1 (HIV-1) acquisition and transmission. HSV-2 glycoprotein D (gD), highly homologous to HSV-1 gD, is essential for viral adhesion, fusion, entry, and spread. It is known that HSV-1 gD can bind herpesvirus entry mediator (HVEM) to trigger NF-κB activation and thereby facilitate viral replication at the early stage of infection. In this study, we found that purified HSV-2 gD triggered NF-κB activation at the early stage of infection, whereas ectopic expression of HSV-2 gD significantly downregulated TNF-α-induced NF-κB activity as well as TNF-α-induced IL-6 and IL-8 expression. Mechanistically, HSV-2 gD inhibited NF-κB, but not IFN-regulatory factor 3 (IRF3), activation and suppressed NF-κB activation mediated by overexpression of TNFR-associated factor 2 (TRAF2), IκB kinase α (IKKα), IKKβ, or p65. Coimmunoprecipitation and binding kinetic analyses demonstrated that HSV-2 gD directly bound to the NF-κB subunit p65 and abolished the nuclear translocation of p65 upon TNF-α stimulation. Mutational analyses further revealed that HSV-2 gD interacted with the region spanning aa 19-187 of p65. Findings in this study together demonstrate that HSV-2 gD interacts with p65 to regulate p65 subcellular localization and thereby prevents NF-κB-dependent gene expression, which may contribute to HSV-2 immune evasion and pathogenesis.

CCL8 mediates crosstalk between endothelial colony forming cells and triple-negative breast cancer cells through IL-8, aggravating invasion and tumorigenicity

Triple-negative breast cancer (TNBC) is an aggressive type of breast cancer with a poor prognosis for which no effective therapeutic measures are currently available. The present study aimed to investigate whether interactions with endothelial colony-forming cells (ECFCs) promote aggressive progression of TNBC cells. Herein, using an indirect co-culture system, we showed that co-culture increased the invasive and migratory phenotypes of both MDA-MB-231 TNBC cells and ECFCs. Through a cytokine antibody array and RT-PCR analysis, we revealed that co-culture markedly induced secretion of the chemokine C-C motif ligand (CCL)8 from ECFCs and that of interleukin (IL)-8 from MDA-MB-231 cells. CCL8 was crucial for ECFC-induced IL-8 secretion and invasion of MDA-MB-231 cells as well as for MDA-MB-231-enhanced MMP-2 secretion and angiogenesis of ECFCs. We suggest c-Jun as a transcription factor for CCL8-induced IL-8 expression in MDA-MB-231 cells. IL-8 was important for co-culture-induced CCL8 and MMP-2 upregulation and invasion of ECFCs. Notably, our findings reveal a positive feedback loop between CCL8 and IL-8, which contributes to the aggressive phenotypes of both ECFC and TNBC cells. Using an MDA-MB-231 cell-based xenograft model, we show that tumor growth and metastasis are increased by co-injected ECFCs in vivo. Increased expression of IL-8 was observed in tissues with bone metastases in mice injected with conditioned media from co-cultured cells. High IL-8 levels are correlated with poor recurrence-free survival in TNBC patients. Together, these results suggest that CCL8 and IL-8 mediate the crosstalk between ECFCs and TNBC, leading to aggravation of tumorigenicity in TNBC.

IL-6 Regulates Hepcidin Expression Via the BMP/SMAD Pathway by Altering BMP6, TMPRSS6 and TfR2 Expressions at Normal and Inflammatory Conditions in BV2 Microglia

The hormone hepcidin plays a central role in controlling iron homeostasis. Iron-mediated hepcidin synthesis is triggered via the BMP/SMAD pathway. At inflammation, mainly IL-6 pro-inflammatory cytokine mediates the regulation of hepcidin via the JAK/STAT signalling pathway. Microglial cells of the central nervous system are able to recognize a broad spectrum of pathogens via toll-like receptors and initiate inflammatory response. Although the regulation of hepcidin synthesis is well described in many tissues, little is known about the inflammation mediated hepcidin regulation in microglia. In this study, we investigated the pathways, which are involved in HAMP regulation in BV2 microglia due to inflammatory mediators and the possible relationships between the iron regulatory pathways. Our results showed that IL-6 produced by resting BV2 cells was crucial in maintaining the basal HAMP expression and hepcidin secretion. It was revealed that IL-6 neutralization decreased both STAT3 and SMAD1/5/9 phosphorylation suggesting that IL-6 proinflammatory cytokine is necessary to maintain SMAD1/5/9 activation. We revealed that IL-6 influences BMP6 and TMPRSS6 protein levels, moreover it modified TfR2 expression, as well. In this study, we revealed that BV2 microglia increased their hepcidin secretion upon IL-6 neutralization although the major regulatory pathways were inhibited. Based on our results it seems that both at inflammation and at normal condition the absence of IL-6 triggered HAMP transcription and hepcidin secretion via the NFκB pathway and possibly by the autocrine effect of TNFα cytokine on BV2 microglia.

Regulation of Transcription Factor NF-κB in Its Natural Habitat: The Nucleus

Activation of the transcription factor NF-κB elicits an individually tailored transcriptional response in order to meet the particular requirements of specific cell types, tissues, or organs. Control of the induction kinetics, amplitude, and termination of gene expression involves multiple layers of NF-κB regulation in the nucleus. Here we discuss some recent advances in our understanding of the mutual relations between NF-κB and chromatin regulators also in the context of different levels of genome organization. Changes in the 3D folding of the genome, as they occur during senescence or in cancer cells, can causally contribute to sustained increases in NF-κB activity. We also highlight the participation of NF-κB in the formation of hierarchically organized super enhancers, which enable the coordinated expression of co-regulated sets of NF-κB target genes. The identification of mechanisms allowing the specific regulation of NF-κB target gene clusters could potentially enable targeted therapeutic interventions, allowing selective interference with subsets of the NF-κB response without a complete inactivation of this key signaling system.

Effects of Carvedilol on the Expression of TLR4 and its Downstream Signaling Pathway in the Liver Tissues of Rats with Cholestatic Liver Fibrosis

Objectives:

This study was designed to investigate the effects of carvedilol on the expression of TLR4 and its downstream signaling pathway in the liver tissues of rats with cholestatic liver fibrosis and provide experimental evidence for clinical treatment of liver fibrosis with carvedilol.

Methods:

A total of fifty male Sprague Dawley rats were randomly divided into five groups (10 rats per group): sham operation (SHAM) control group, bile duct ligation (BDL) model group, low-dose carvedilol treatment group (0.1mg·kg-1·d-1), medium-dose carvedilol treatment group (1mg·kg-1·d-1), and high-dose carvedilol treatment group (10mg·kg-1·d-1). Rat hepatic fibrosis model was established by applying BDL. Forty-eight hours after the operation, carvedilol was administered twice a day. The blood and liver were simultaneously collected under the aseptic condition for further detection in two weeks after the operation. The alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBil) and albumin (Alb) in serum were measured. HE and Masson staining were used to determine hepatic fibrosis degree. Hydroxyproline assay was employed to detect liver collagen synthesis. Western Blot was used to measure the expression of TLR4, NF-κB p65 and β-arrestin2 protein. Quantitative analysis of TLR4, MyD88, TNF-α and IL-6 mRNA was performed by Realtime-PCR.

Results:

Compared with the SHAM group, the BDL group showed obvious liver injury, increased levels of inflammatory factors, and continued progression of liver fibrosis. The above changes in the BDL group were alleviated in the carvedilol treatment groups. The improvement effects augmented as dosages increased. In addition, compared with the BDL group, the reduction of the expressions of TLR4, MyD88 and NF-κB p65 in liver tissues and the increase of the expression of β -arrestin2 in the high-dose carvedilol group were more significant.

Conclusions:

Carvedilol can reduce the release of inflammatory mediators by downregulating TLR4 expression and inhibiting its downstream signaling pathway, thus playing a potential therapeutic role in cholestatic liver fibrosis.

Role of the NF-κB system in context-specific tuning of the inflammatory gene response

The canonical NF-κB pathway instructs the expression of inflammatory genes by the RelA:p50 transcription factor in response to diverse cell-activating stimuli. However, this mainstay RelA:p50 transcriptional output must also be curated so as to provide for stimulus-type-specific and cell-type-specific inflammatory responses adapted to the local tissue-microenvironment. Here, we summarize the fundamental mechanisms regulating RelA:p50-mediated gene expressions and discuss how the NF-κB system imparts specificity in the inflammatory gene program. We put forward a conceptual framework where the dynamical attributes and the composition of the nuclear NF-κB complexes cumulatively instruct context-specific inflammatory gene patterns. We propose that integrating mechanistic knowledge and systems-level analyses may offer further insights on NF-κB-mediated inflammatory gene control in the future.

Mutual regulation of metabolic processes and proinflammatory NF-κB signaling

The nuclear factor kappa B (NF-κB) signaling system, a key regulator of immunologic processes, also affects a plethora of metabolic changes associated with inflammation and the immune response. NF-κB-regulating signaling cascades, in concert with NF-κB-mediated transcriptional events, control the metabolism at several levels. NF-κB modulates apical components of metabolic processes including metabolic hormones such as insulin and glucagon, the cellular master switches 5' AMP-activated protein kinase and mTOR, and also numerous metabolic enzymes and their respective regulators. Vice versa, metabolic enzymes and their products also exert multilevel control of NF-κB activity, thereby creating a highly connected regulatory network. These insights have resulted in the identification of the noncanonical IκB kinase kinases IκB kinase ɛ and TBK1, which are upregulated by overnutrition, and may therefore be suitable potential therapeutic targets for metabolic syndromes. An inhibitor interfering with the activity of both kinases reduces obesity-related metabolic dysfunctions in mouse models and the encouraging results from a recent clinical trial indicate that targeting these NF-κB pathway components improves glucose homeostasis in a subset of patients with type 2 diabetes.

Nuclear Factor Kappa B Signaling Complexes in Acute Inflammation

Significance: Nuclear factor kappa B (NF-κB) is a master regulator of the inflammatory response and represents a key regulatory node in the complex inflammatory signaling network. In addition, selective NF-κB transcriptional activity on specific target genes occurs through the control of redox-sensitive NF-κB interactions. Recent Advances: The selective NF-κB response is mediated by redox-modulated NF-κB complexes with ribosomal protein S3 (RPS3), Pirin (PIR). cAMP response element-binding (CREB)-binding protein (CBP)/p300, peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), activator protein-1 (AP-1), signal transducer and activator of transcription 3 (STAT3), early growth response protein 1 (EGR-1), and SP-1. NF-κB is cooperatively coactivated with AP-1, STAT3, EGR-1, and SP-1 during the inflammatory process, whereas NF-κB complexes with CBP/p300 and PGC-1α regulate the expression of antioxidant genes. PGC-1α may act as selective repressor of phospho-p65 toward interleukin-6 (IL-6) in acute inflammation. p65 and nuclear factor erythroid 2-related factor 2 (NRF2) compete for binding to coactivator CBP/p300 playing opposite roles in the regulation of inflammatory genes. S-nitrosylation or tyrosine nitration favors the recruitment of specific NF-κB subunits to κB sites. Critical Issues: NF-κB is a redox-sensitive transcription factor that forms specific signaling complexes to regulate selectively the expression of target genes in acute inflammation. Protein-protein interactions with coregulatory proteins, other transcription factors, and chromatin-remodeling proteins provide transcriptional specificity to NF-κB. Furthermore, different NF-κB subunits may form distinct redox-sensitive homo- and heterodimers with distinct affinities for κB sites. Future Directions: Further research is required to elucidate the whole NF-κB interactome to fully characterize the complex NF-κB signaling network in redox signaling, inflammation, and cancer.

A single ChIP-seq dataset is sufficient for comprehensive analysis of motifs co-occurrence with MCOT package

Recognition of composite elements consisting of two transcription factor binding sites gets behind the studies of tissue-, stage- and condition-specific transcription. Genome-wide data on transcription factor binding generated with ChIP-seq method facilitate an identification of composite elements, but the existing bioinformatics tools either require ChIP-seq datasets for both partner transcription factors, or omit composite elements with motifs overlapping. Here we present an universal Motifs Co-Occurrence Tool (MCOT) that retrieves maximum information about overrepresented composite elements from a single ChIP-seq dataset. This includes homo- and heterotypic composite elements of four mutual orientations of motifs, separated with a spacer or overlapping, even if recognition of motifs within composite element requires various stringencies. Analysis of 52 ChIP-seq datasets for 18 human transcription factors confirmed that for over 60% of analyzed datasets and transcription factors predicted co-occurrence of motifs implied experimentally proven protein-protein interaction of respecting transcription factors. Analysis of 164 ChIP-seq datasets for 57 mammalian transcription factors showed that abundance of predicted composite elements with an overlap of motifs compared to those with a spacer more than doubled; and they had 1.5-fold increase of asymmetrical pairs of motifs with one more conservative 'leading' motif and another one 'guided'.

Chloroquine and Rapamycin Augment Interleukin-37 Expression via the LC3, ERK, and AP-1 Axis in the Presence of Lipopolysaccharides

IL-37 is a cytokine that plays critical protective roles in many metabolic inflammatory diseases, and its therapeutic potential has been confirmed by exogenous IL-37 administration. However, its regulatory mechanisms remain unclear. U937 cells were treated with autophagy-modifying reagents (3-MA, chloroquine, and rapamycin) with or without LPS stimulation. Thereafter, IL-37 expression and autophagic markers (Beclin1, P62/SQSTM1, and LC3) were determined. For regulatory signal pathways, phosphorylated proteins of NF-κB (p65 and IκBα), AP-1 (c-Fos/c-Jun), and MAPK signal pathways (Erk1/2 and p38 MAPK) were quantified, and the agonists and antagonists of MAPK and NF-κB pathways were also used. Healthy human peripheral blood mononuclear cells were treated similarly to confirm our results. Four rhesus monkeys were also administered chloroquine to evaluate IL-37 induction in vivo and its bioactivity on CD4 proliferation and activation. IL-37 was upregulated by rapamycin and chloroquine in both U937 cells and human PBMCs in the presence of LPS. IL-37 was preferentially induced in autophagic cells associated with LC3 conversion. AP-1 and p65 binding motifs could be deduced in the sequence of the IL-37 promoter. Inductive IL-37 expression was accompanied with increased phosphorylated Erk1/2 and AP-1 and could be completely abolished by an Erk1/2 inhibitor or augmented by Erk1/2 agonists. In monkeys, chloroquine increased IL-37 expression, which was inversely correlated with CD4 proliferation and phosphorylated STAT3. IL-37 levels were induced by rapamycin and chloroquine through the LC3, Erk1/2, and NF-κB/AP-1 pathways. Functional IL-37 could also be induced in vivo.

Single-Cell Analysis of Multiple Steps of Dynamic NF-κB Regulation in Interleukin-1α-Triggered Tumor Cells Using Proximity Ligation Assays

The frequently occurring heterogeneity of cancer cells and their functional interaction with immune cells in the tumor microenvironment raises the need to study signaling pathways at the single cell level with high precision, sensitivity, and spatial resolution. As aberrant NF-κB activity has been implicated in almost all steps of cancer development, we analyzed the dynamic regulation and activation status of the canonical NF-κB pathway in control and IL-1α-stimulated individual cells using proximity ligation assays (PLAs). These systematic experiments allowed the visualization of the dynamic dissociation and re-formation of endogenous p65/IκBα complexes and the nuclear translocation of NF-κB p50/p65 dimers. PLA combined with immunostaining for p65 or with NFKBIA single molecule mRNA-FISH facilitated the analysis of (i) further levels of the NF-κB pathway, (i) its functionality for downstream gene expression, and (iii) the heterogeneity of the NF-κB response in individual cells. PLA also revealed the interaction between NF-κB p65 and the P-body component DCP1a, a new p65 interactor that contributes to efficient p65 NF-κB nuclear translocation. In summary, these data show that PLA technology faithfully mirrored all aspects of dynamic NF-κB regulation, thus allowing molecular diagnostics of this key pathway at the single cell level which will be required for future precision medicine.

Chemotherapeutic Drugs Inhibiting Topoisomerase 1 Activity Impede Cytokine-Induced and NF-κB p65-Regulated Gene Expression

Inhibitors of DNA topoisomerase I (TOP1), an enzyme relieving torsional stress of DNA by generating transient single-strand breaks, are clinically used to treat ovarian, small cell lung and cervical cancer. As torsional stress is generated during transcription by progression of RNA polymerase II through the transcribed gene, we tested the effects of camptothecin and of the approved TOP1 inhibitors Topotecan and SN-38 on TNFα-induced gene expression. RNA-seq experiments showed that inhibition of TOP1 but not of TOP2 activity suppressed the vast majority of TNFα-triggered genes. The TOP1 effects were fully reversible and preferentially affected long genes. TNFα stimulation led to inducible recruitment of TOP1 to the gene body of IL8, where its inhibition by camptothecin reduced transcription elongation and also led to altered histone H3 acetylation. Together, these data show that TOP1 inhibitors potently suppress expression of proinflammatory cytokines, a feature that may contribute to the increased infection risk occurring in tumor patients treated with these agents. On the other hand, TOP1 inhibitors could also be considered as a therapeutic option in order to interfere with exaggerated cytokine expression seen in several inflammatory diseases.