Gamma interferon and lipopolysaccharide interact at the level of transcription to induce tumor necrosis factor alpha expression

Effects of parity and early pregnancy on peripheral blood leukocytes in dairy cattle

Subfertility remains a major problem in the dairy industry. Only 35-40% of high-yielding dairy cows and 55-65% of nonlactating heifers become pregnant after their first service. The immune system plays a critical role in the establishment of pregnancy. However, it can also create challenges for embryo survival and contribute to reduced fertility. We conducted 2 separate experiments to characterize changes in subsets of peripheral blood leukocytes (PBL) and their phenotype over the estrous cycle and early pregnancy in heifers and cows. We used flow cytometry and RT-qPCR to assess protein and mRNA expression of molecules important for immune function. We observed that monocytes and T cells were most affected by pregnancy status in heifers, whereas, CD8+ lymphocytes and natural killer (NK) cells were most affected during early pregnancy in cows. Changes in immune parameters measured appeared to be greater in heifers than cows including changes in expression of numerous immune function molecules. To test the hypothesis, we conducted a third experiment to simultaneously analyze the immunological responses to pregnancy between cows and heifers. We observed that cows had greater expression of proinflammatory cytokines and molecules associated with leukocyte migration and phagocytosis compared to heifers. Moreover, animals that failed to become pregnant showed altered expression of anti-inflammatory molecules. Overall, these findings support the hypothesis that early pregnancy signaling alters the proportions and functions of peripheral blood immune cells and differences between cows and heifers may yield insight into the reduced fertility of mature lactating dairy cows.

Ependymal cells undergo astrocyte-like reactivity in response to neuroinflammation

Ependymal cells form a specialized brain-cerebrospinal fluid (CSF) interface and regulate local CSF microcirculation. It is becoming increasingly recognized that ependymal cells assume a reactive state in response to aging and disease, including conditions involving hypoxia, hydrocephalus, neurodegeneration, and neuroinflammation. Yet what transcriptional signatures govern these reactive states and whether this reactivity shares any similarities with classical descriptions of glial reactivity (i.e., in astrocytes) remain largely unexplored. Using single-cell transcriptomics, we interrogated this phenomenon by directly comparing the reactive ependymal cell transcriptome to the reactive astrocyte transcriptome using a well-established model of autoimmune-mediated neuroinflammation (MOG35-55 EAE). In doing so, we unveiled core glial reactivity-associated genes that defined the reactive ependymal cell and astrocyte response to MOG35-55 EAE. Interestingly, known reactive astrocyte genes from other CNS injury/disease contexts were also up-regulated by MOG35-55 EAE ependymal cells, suggesting that this state may be conserved in response to a variety of pathologies. We were also able to recapitulate features of the reactive ependymal cell state acutely using a classic neuroinflammatory cocktail (IFNγ/LPS) both in vitro and in vivo. Taken together, by comparing reactive ependymal cells and astrocytes, we identified a conserved signature underlying glial reactivity that was present in several neuroinflammatory contexts. Future work will explore the mechanisms driving ependymal reactivity and assess downstream functional consequences.

Development of an in vitro co-culture model using Caco-2 and J774A.1 cells to mimic intestinal inflammation

In vitro models that mimic the pathophysiology in vivo are important tools to study mechanisms of disease and assess the pharmacology and toxicity of drugs. In this work, we report the development of a novel model of intestinal inflammation. This model is based on the co-culture of intestinal epithelial Caco-2 cells and murine J774A.1 macrophages. The model is shown to mimic the intestinal barrier in both healthy and inflamed state. In the healthy state, without external stimulation, Caco-2 and J774A.1 cells were co-cultured in one system without affecting the barrier integrity of intestinal epithelial cells and without inducing release of cytokines from macrophages. To mimic the inflamed intestine, Caco-2 cells were primed with an optimised cytokine cocktail (TNF-⍺, IFN-γ and IL-1β) and J774A.1 cells were pre-exposed to lipopolysaccharide (LPS) and IFN-γ for 24 h before combining the two cell lines into co-culture. In these conditions, a significant disruption of the epithelial barrier and an increase in pro-inflammatory cytokine (TNF-⍺ and IL-6) levels released from macrophages were detected. The data also show that inflammation in the co-culture model was temporary and reversible upon the removal of the inflammatory stimulus. This new in vitro model could be a valuable tool for investigating the safety and efficacy of drugs in the context of intestinal inflammation and provides advantages over other reported co-culture models of intestinal inflammation in terms of cost and simplicity.

Protective Activities of Growth Hormone-Releasing Hormone Antagonists against Toxin-Induced Endothelial Injury

GHRH regulates the secretion of GH from the anterior pituitary gland, previously associated with cancer progression and inflammation. An emerging body of evidence suggests that GHRHAnt support endothelial barrier function, but the mechanisms mediating these events are not completely understood. In the present study, it is demonstrated that the GHRHAnt JV-1-36 counteracts barrier dysfunction due to LPS or LTA treatment in HUVECs, utilizing the Dextran-FITC assay. Moreover, it is shown in BPAECs that these bacterial toxins increase ROS generation, and that this effect is counteracted by JV-1-36, which reinstates the redox balance. The possible involvement of NEK2 in the beneficial activities of GHRHAnt in IFN-γ- and LPS-triggered hyperpermeability was also assessed, since that kinase is involved in inflammatory responses. NEK2 was increased in the inflamed cells, and JV-1-36 counteracted those endothelial events. Our data support the beneficial effects of GHRHAnt in toxin-induced endothelial injury.

An early glycolysis burst in microglia regulates mitochondrial dysfunction in oligodendrocytes under neuroinflammation

Metabolism and energy processes governing oligodendrocyte function during neuroinflammatory disease are of great interest. However, how varied cellular environments affect oligodendrocyte activity during neuroinflammation is unknown. We demonstrate that activated microglial energy metabolism controls oligodendrocyte mitochondrial respiration and activity. Lipopolysaccharide/interferon gamma promote glycolysis and decrease mitochondrial respiration and myelin protein synthesis in rat brain glial cells. Enriched microglia showed an early burst in glycolysis. In microglia-conditioned medium, oligodendrocytes did not respire and expressed less myelin. SCENITH revealed metabolic derangement in microglia and O4-positive oligodendrocytes in endotoxemia and experimental autoimmune encephalitogenic models. The early burst of glycolysis in microglia was mediated by PDPK1 and protein kinase B/AKT signaling. We found that microglia-produced NO and itaconate, a tricarboxylic acid bifurcated metabolite, reduced mitochondrial respiration in oligodendrocytes. During inflammation, we discovered a signaling pathway in microglia that could be used as a therapeutic target to restore mitochondrial function in oligodendrocytes and induce remyelination.

Reduced IL-8 Secretion by NOD-like and Toll-like Receptors in Blood Cells from COVID-19 Patients

Severe inflammatory responses are associated with the misbalance of innate and adaptive immunity. TLRs, NLRs, and cytokine receptors play an important role in pathogen sensing and intracellular control, which remains unclear in COVID-19. This study aimed to evaluate IL-8 production in blood cells from COVID-19 patients in a two-week follow-up evaluation. Blood samples were taken at admission (t1) and after 14 days of hospitalization (t2). The functionality of TLR2, TLR4, TLR7/8, TLR9, NOD1, and NOD2 innate receptors and IL-12 and IFN-γ cytokine receptors was evaluated by whole blood stimulation with specific synthetic receptor agonists through the quantification of IL-8, TNF-α, or IFN-γ. At admission, ligand-dependent IL-8 secretion was 6.4, 13, and 2.5 times lower for TLR2, TLR4, and endosomal TLR7/8 receptors, respectively, in patients than in healthy controls. Additionally, IL-12 receptor-induced IFN-γ secretion was lower in COVID-19 patients than in healthy subjects. We evaluated the same parameters after 14 days and observed significantly higher responses for TLR2, TLR4, TLR7/8, TLR9, and NOD1, NOD2, and IFN-γ receptors. In conclusion, the low secretion of IL-8 through stimulation with agonists of TLR2, TLR4, TLR7/8, TLR9, and NOD2 at t1 suggests their possible contribution to immunosuppression following hyperinflammation in COVID-19 disease.

In Vitro Cytotoxicity and Cytokine Production by Lipid-Substituted Low Molecular Weight Branched PEIs Used for Gene Delivery

Lipid-modified low molecular weight branched polyethyleneimines (PEIs) are promising non-viral gene delivery systems that have been successfully explored for treatment of various diseases. The present study aims to determine in vitro safety of these delivery systems based on assessment of cytotoxicity with peripheral blood mononuclear cells (PBMCs), hemolysis with human red blood cells (RBC) and cytokine secretion from several sources of PBMCs. The viability of cells treated with lipopolymer/pDNA complexes was dependent on the polymer:pDNA ratio used but remained low at therapeutically relevant concentrations for most lipopolymers, except for the propionic acid substituted PEIs. The extent of hemolysis was minimal and below the accepted safety levels with most of the lipopolymers; however, some linoleic acid substituted PEIs yielded significant hemolysis activity. Unlike strong cytokine secretion from PMA/IO stimulated cells, most lipopolymer/pDNA complexes remained non-responsive, showing minimal changes in cytokine secretion (TNF-α, IL-6 and IFN-γ) irrespective of the lipopolymer/pDNA formulations. The 0.6 kDa PEI with lauric acid substituent displayed slight cytokine upregulation, however it remained low relative to the positive controls. This study demonstrated that the lipid modified LMW PEIs are expected to be safe in contact with blood components. However, close attention to lipopolymer concentration and ratio of polymer to pDNA in formulations might be required for individual lipopolymers for optimal safety response in nucleic acid therapies. STATEMENT OF SIGNIFICANCE: : This manuscript investigated the safety aspects of various lipid modified low molecular weight polyethylenimine (LMW-PEI) polymers employed for pDNA delivery through in vitro studies. Using peripheral blood mononuclear cells (PBMCs) from multiple sources, we show that the hemolysis ability was minimal for most polymers, although a particular lipid substituent (linoleic acid) at specific ratios exhibited hemolysis. The levels of pro-inflammatory cytokines (TNF-α, IL-6 and IFN-γ) were slightly upregulated only with a lauric acid substituted 0.6PEI, but remained low relative to positive control treatments. We further report the beneficial effect of polyacrylic acid additives on hemolysis and cytokine secretion to a reasonable extent. This study confirms the feasibility of using LMW-PEI as safe delivery agents for various therapeutic purposes.

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.

JAK2-STAT Epigenetically Regulates Tolerized Genes in Monocytes in the First Encounter With Gram-Negative Bacterial Endotoxins in Sepsis

Microbial challenges, such as widespread bacterial infection in sepsis, induce endotoxin tolerance, a state of hyporesponsiveness to subsequent infections. The participation of DNA methylation in this process is poorly known. In this study, we perform integrated analysis of DNA methylation and transcriptional changes following in vitro exposure to gram-negative bacterial lipopolysaccharide, together with analysis of ex vivo monocytes from septic patients. We identify TET2-mediated demethylation and transcriptional activation of inflammation-related genes that is specific to toll-like receptor stimulation. Changes also involve phosphorylation of STAT1, STAT3 and STAT5, elements of the JAK2 pathway. JAK2 pathway inhibition impairs the activation of tolerized genes on the first encounter with lipopolysaccharide. We then confirm the implication of the JAK2-STAT pathway in the aberrant DNA methylome of patients with sepsis caused by gram-negative bacteria. Finally, JAK2 inhibition in monocytes partially recapitulates the expression changes produced in the immunosuppressive cellular state acquired by monocytes from gram-negative sepsis, as described by single cell-RNA-sequencing. Our study evidences both the crucial role the JAK2-STAT pathway in epigenetic regulation and initial response of the tolerized genes to gram-negative bacterial endotoxins and provides a pharmacological target to prevent exacerbated responses.

The response of two polar monocyte subsets to inflammation

Macrophages are a central component of innate immunity that play an important role in the defense of the organism. Macrophages are highly plastic and are activated by interaction with other cells and environmental factors. In this work, we study the effect of lipopolysaccharide on macrophages derived from the two most polar (CD14+ and CD16+ monocytes) as well as the intermediate subset of blood monocytes from healthy donors and assess what happens to the subset most prone to polarization on the transcriptomic and proteomic level. It has been shown that, according to primary pro-inflammatory polarization markers, their cytokine profile, and their phagocytic activity, macrophages derived from CD14+ monocytes exhibit higher sensitivity to inducers of pro-inflammatory polarization. Flow cytometry analysis revealed increased levels of CD86, while secretome analysis demonstrated significant increase of pro-inflammatory and anti-inflammatory cytokines observed in CD14+-derived macrophages, as compared to CD16+-derived macrophages in conditioned media. Assessment of the transcriptome and proteome of CD14+-derived macrophages with further bioinformatic analysis identified the most significant differences after polarization towards the pro-inflammatory phenotype. Immune-, membrane-, IFN-γ-, cytokine-, and defense-associated pathways were found significantly prevalent, while downregulated pathways were represented by RNA binding-, housekeeping-, exocytosis-, intracellular transport-, peptide and amide metabolic-related signaling. This data could be useful for macrophage-based cell therapeutics of cancer, as it provides additional background for the manipulation of donor monocytes intended for back transplantation.

Heat Stress in Broiler Chickens and the Effect of Dietary Polyphenols, with Special Reference to Willow (Salix spp.) Bark Supplements-A Review

Over the last decade, there has been a growing interest in the use of a wide range of phytoadditives to counteract the harmful effects of heat stress in poultry. Willow (Salix spp.) is a tree with a long history. Among various forms, willow bark is an important natural source of salicin, β-O-glucoside of saligenin, but also of polyphenols (flavonoids and condensed tannins) with antioxidant, antimicrobial, and anti-inflammatory activity. In light of this, the current review presents some literature data aiming to: (1) describe the relationship between heat stress and oxidative stress in broilers, (2) present or summarize literature data on the chemical composition of Salix species, (3) summarize the mechanisms of action of willow bark in heat-stressed broilers, and (4) present different biological effects of the extract of Salix species in different experimental models.

Molecular characterization and expression analysis of rockfish (Sebastes schlegelii) viperin, and its ability to enervate RNA virus transcription and replication in vitro

Viperin, also known as RSAD2 (Radical S-adenosyl methionine domain containing 2), is an interferon-induced endoplasmic reticulum-associated antiviral protein. Previous studies have shown that viperin levels are elevated in the presence of viral RNA, but it has rarely been characterized in marine organisms. This study was designed to functionally characterize rockfish viperin (SsVip), to examine the effects of different immune stimulants on its expression, and to determine its subcellular localization. SsVip is a 349 amino acid protein with a predicted molecular mass of 40.24 kDa. It contains an S-adenosyl l-methionine binding conserved domain with a CNYKCGFC sequence. Unchallenged tissue expression analysis using quantitative real time PCR (qPCR) revealed SsVip expression to be the highest in the blood, followed by the spleen. When challenged with poly I:C, SsVip was upregulated by approximately 60-fold in the blood after 24 h, and approximately 50-fold in the spleen after 12 h. Notable upregulation was detected throughout the poly I:C challenge experiment in both tissues. Significant expression of SsVip was detected in the blood following Streptococcus iniae and lipopolysaccharide challenge, and viral hemorrhagic septicemia virus (VHSV) gene transcription was significantly downregulated during SsVip overexpression. Furthermore, cell viability assay and virus titer quantification with the presence of SsVip revealed a significant reduction in virus replication. As with previously identified viperin counterparts, SsVip was localized in the endoplasmic reticulum. Our findings show that SsVip is an antiviral protein crucial to innate immune defense.

The underdeveloped innate immunity in embryonic stem cells: The molecular basis and biological perspectives from early embryogenesis

Embryonic stem cells (ESCs) have been intensively studied as a promising cell source for regenerative medicine. The rapid advancements in the field have not only proven the feasibility of ESC-based cell therapy, but also led to a better understanding of pluripotent stem cells (PSCs) as a unique cell population at an early stage of embryogenesis. Recent studies have revealed that both human and mouse ESCs have attenuated innate immune responses to infectious agents and inflammatory cytokines. These findings raise interesting questions about the rationale for ESCs, the PSCs experimentally derived from preimplantation stage embryos, to not have an innate defense mechanism that has been adapted so well in somatic cells. All somatic cells have innate immune systems that can be activated by pathogen-associated molecular patterns (PAMPs) or cellular damage-associated molecular patterns (DAMPs), leading to production of cytokines. The underdeveloped innate immunity represents a unique property of PSCs that may have important implications. This review discusses the immunological properties of PSCs, the molecular basis underlying their diminished innate immune responses, and the hypothesis that the attenuated innate immune responses could be an adaptive mechanism that allows PSCs to avoid cytotoxicity associated with inflammation and immune responses during early embryogenesis.

Characterization of embryonic stem cell-differentiated fibroblasts as mesenchymal stem cells with robust expansion capacity and attenuated innate immunity

BACKGROUND

Mesenchymal stem cells (MSCs) isolated from adult tissues (Ad-MSCs) have shown great promise for use in regenerative medicine. However, their poor in vitro expansion capacity and tissue scarcity have been major limitations. In this study, we demonstrate that mouse embryonic stem cells (mESCs) can differentiate into cells with MSC properties.

METHODS

Using previously established methods that characterize Ad-MSCs, we analyzed mESC-differentiated fibroblasts (mESC-FBs), including plastic adherence, clonogenic growth, MSC marker expression, tri-lineage differentiation potential, and the capacity to express immunomodulators.

RESULTS

Although previously characterized as mESC-differentiated fibroblasts (mESC-FBs), these cells exhibit major properties of Ad-MSCs. However, mESC-FBs also display unique features inherited from ESCs, including robust expansion capacity, senescence resistance, and attenuated innate immunity. In particular, mESC-FBs are insensitive to bacterial endotoxin (lipopolysaccharide, LPS) and do not express LPS-induced inflammatory molecules, in contrast to bone marrow (BM)-MSCs. We further demonstrate that mESC-FBs are resistant to the cytotoxicity associated with inflammatory cytokines, bacterial endotoxins (LPS and heat-killed bacteria), and macrophage-mediated inflammation.

CONCLUSIONS

While it remains to be determined how the unique properties of mESC-FBs will affect their immunoregulatory activity under an in vivo condition, our findings demonstrate that ESCs could be used as an alternative source to generate a new class of ESC-MSCs with unique features potentially useful in regenerative medicine.

Immune senescence, epigenetics and autoimmunity

Aging of the immune system in humans and animals is characterized by a decline in both adaptive and innate immune responses. Paradoxically, aging is also associated with a state of chronic inflammation ("inflammaging") and an increased likelihood of developing autoimmune diseases. Epigenetic changes in non-dividing and dividing cells, including immune cells, due to environmental factors contribute to the inflammation and autoimmunity that characterize both the state and diseases of aging. Here, we review the epigenetic mechanisms involved in the development of immune senescence and autoimmunity in old age.

Toll-Like Receptor Ligands and Interferon-γ Synergize for Induction of Antitumor M1 Macrophages

Tumor-associated macrophages may either promote or suppress tumor growth depending on their activation status. Interferon-γ (IFN-γ) has been identified as a key factor for inducing tumoricidal M1 phenotype in macrophages. However, it remains unclear whether IFN-γ is sufficient or if additional stimuli are required. Here, we tested IFN-γ and a panel of toll-like receptor (TLR) agonists for the ability to activate murine macrophages toward a tumoricidal M1 phenotype. The following TLR ligands were used: TLR1/TLR2 agonist Pam3CSK4, TLR2/TLR6 agonist lipotechoic acid, TLR3 agonist poly(I:C), TLR4 agonist lipopolysaccharide (LPS), TLR5 agonist flagellin, TLR7 agonist CL264, and TLR9 agonist CpG. We used an in vitro growth inhibition assay to measure both cytotoxic and cytostatic activity of mouse macrophages against Lewis lung carcinoma (LLC) and MOPC315 plasmacytoma tumor cells. Production of nitric oxide (NO) and cytokines by activated macrophages was quantified. We found that IFN-γ alone was not able to render macrophages tumoricidal. Similarly, macrophage activation with single TLR agonists was inefficient. In sharp contrast, IFN-γ was shown to synergize with TLR agonists for induction of macrophage tumoricidal activity and production of both NO and pro-inflammatory cytokines (TNF-α, IL-12p40, and IL-12p70). Furthermore, IFN-γ was shown to suppress macrophage IL-10 secretion induced by TLR agonists. NO production was necessary for macrophage tumoricidal activity. We conclude that two signals from the microenvironment are required for optimal induction of antitumor M1 macrophage phenotype. Combination treatment with IFN-γ and TLR agonists may offer new avenues for macrophage-based cancer immunotherapy.

Baseline JAK phosphorylation profile of peripheral blood leukocytes, studied by whole blood phosphospecific flow cytometry, is associated with 1-year treatment response in early rheumatoid arthritis

Background

We found recently that baseline signal transducer and activator of transcription 3 phosphorylation in peripheral blood CD4⁺ T cells of patients with early rheumatoid arthritis (RA) is associated with treatment response to synthetic disease-modifying antirheumatic drugs (DMARDs). This prompted us to study the baseline phosphorylation profiles of Janus kinases (JAKs) in blood leukocytes with respect to treatment response in early RA.

Methods

Thirty-five DMARD-naïve patients with early RA provided blood samples for whole blood flow cytometric determination of phosphorylation of JAKs in CD4⁺ and CD8⁺ T cells, CD19⁺ B cells, and CD14⁺ monocytes. Treatment response was determined after 1 year of treatment with synthetic DMARDs, with remission defined as absence of tender and swollen joints and normal erythrocyte sedimentation rate. Exact logistic regression was used to investigate the association of baseline variables with treatment response. Ninety-five percent CIs of means were estimated by bias-corrected bootstrapping.

Results

High JAK3 phosphorylation in CD4⁺ and CD8⁺ T cells, CD19⁺ B cells, and CD14⁺ monocytes and low JAK2 phosphorylation in CD14⁺ monocytes were significantly associated with remission following treatment with synthetic DMARDs.

Conclusions

Baseline JAK phosphorylation profile in peripheral blood leukocytes may provide a means to predict treatment response achieved by synthetic DMARDs among patients with early RA.

Idiosyncratic Drug-Induced Liver Injury: Is Drug-Cytokine Interaction the Linchpin?

Idiosyncratic drug-induced liver injury continues to be a human health problem in part because drugs that cause these reactions are not identified in current preclinical testing and because progress in prevention is hampered by incomplete knowledge of mechanisms that underlie these adverse responses. Several hypotheses involving adaptive immune responses, inflammatory stress, inability to adapt to stress, and multiple, concurrent factors have been proposed. Yet much remains unknown about how drugs interact with the liver to effect death of hepatocytes. Evidence supporting hypotheses implicating adaptive or innate immune responses in afflicted patients has begun to emerge and is bolstered by results obtained in experimental animal models and in vitro systems. A commonality in adaptive and innate immunity is the production of cytokines, including interferon-γ (IFNγ). IFNγ initiates cell signaling pathways that culminate in cell death or inhibition of proliferative repair. Tumor necrosis factor-α, another cytokine prominent in immune responses, can also promote cell death. Furthermore, tumor necrosis factor-α interacts with IFNγ, leading to enhanced cellular responses to each cytokine. In this short review, we propose that the interaction of drugs with these cytokines contributes to idiosyncratic drug-induced liver injury, and mechanisms by which this could occur are discussed.

Influence of Promoter Polymorphisms of the TNF-α (-308G/A) and IL-6 (-174G/C) Genes on Therapeutic Response to Etanercept in Rheumatoid Arthritis

Background

The study was undertaken to assess the influence of functional -308G/A TNF-α (rs 1800629) and -174G/C IL-6 (rs1800795) promoter polymorphisms on the therapeutic response to etanercept, a TNF-α blocker, in patients with rheumatoid arthritis (RA).

Methods

Seventy-three patients suffering from active RA were studied, at baseline and 6 and 12 months after therapy. The therapeutic response was estimated according to the European League Against Rheumatism response criteria. Patients were genotyped for -308G/A TNF-α and -174G/C IL-6 polymorphisms by the PCR-RFLP method, and the influence of genotype on etanercept response was assessed.

Results

No difference in the percentage of responders (patients who had DAS28 improvement > 1.2) between patients with the TNF-α-308GG and GA and AA genotype was detected after 6 and 12 months of treatment. After 12 months of treatment the percentage of responders was significantly increased in patients with the IL-6 -174GG genotype compared with those with the GC or CC genotype (p=0.006 by Chi-square test). Evaluation of the patients according to their combined IL-6/TNF-α genotypes showed that patients with the IL-6 -174GG / TNF-α-308GG genotype were more frequent among the responders compared to those with other combined genotypes (p=0.022 by Chi-square test). More precisely, all patients with the combined IL-6 -174GG / TNF-α-308GG genotype were responders after 12 months of etanercept treatment.

Conclusions

The study suggests that patients who are genetically low TNF-α and IL-6 producers are the best responders to etanercept therapy.

Identification of transactivation-responsive DNA-binding protein 43 (TARDBP43; TDP-43) as a novel factor for TNF-α expression upon lipopolysaccharide stimulation in human monocytes

BACKGROUND AND OBJECTIVE

Tumor necrosis factor alpha (TNF-α) is a major cytokine implicated in various inflammatory diseases. The nature of the nuclear factors associated with human TNF-α gene regulation is not well elucidated. We previously identified a novel region located from -550 to -487 in human TNF-α promoter that did not contain the reported binding sites for nuclear factor kappa B (NF-κB) but showed lipopolysaccharide (LPS)-induced transcriptional activity. The purpose of this study is to identify novel factors that bind to the promoter region and regulate TNF-α expression.

MATERIAL AND METHODS

To identify DNA-binding proteins that bound to the target region of TNF-α promoter, a cDNA library from LPS-stimulated human monocytic cell line THP-1 was screened using a yeast one-hybrid system. Cellular localizations of the DNA-binding protein in the cells were examined by subcellular immunocytochemistry. Nuclear amounts of the protein in LPS-stimulated THP-1 cells were identified by western blot analysis. Expression of mRNA of the protein in the cells was quantified by real-time polymerase chain reaction. Electrophoretic mobility shift assays were performed to confirm the DNA-binding profile. Overexpression of the protein and knockdown of the gene were also performed to investigate the role for TNF-α expression.

RESULTS

Several candidates were identified from the cDNA library and transactivation-responsive DNA-binding protein 43 (TARDBP43; TDP-43) was focused on. Western blot analysis revealed that nuclear TDP-43 protein was increased in the LPS-stimulated THP-1 cells. Expression of TDP-43 mRNA was already enhanced before TNF-α induction by LPS. Electrophoretic mobility shift assay analysis showed that nuclear extracts obtained by overexpressing FLAG-tagged TDP-43 bound to the -550 to -487 TNF-α promoter fragments. Overexpression of TDP-43 in THP-1 cells resulted in an increase of TNF-α expression. Knockdown of TDP-43 in THP-1 cells downregulated TNF-α expression.

CONCLUSION

We identified TDP-43 as one of the novel TNF-α factors and found that it bound to the LPS-responsive element in the TNF-α promoter to increase TNF-α expression.

Noncoding RNAs and LRRFIP1 regulate TNF expression

Noncoding RNAs have been implicated in the regulation of expression of numerous genes; however, the mechanism is not fully understood. We identified bidirectional, long noncoding RNAs upstream of the TNF gene using five different methods. They arose in a region where the repressors LRRFIP1, EZH2, and SUZ12 were demonstrated to bind, suggesting a role in repression. The noncoding RNAs were polyadenylated, capped, and chromatin associated. Knockdown of the noncoding RNAs was associated with derepression of TNF mRNA and diminished binding of LRRFIP1 to both RNA targets and chromatin. Overexpression of the noncoding RNAs led to diminished expression of TNF and recruitment of repressor proteins to the locus. One repressor protein, LRRFIP1, bound directly to the noncoding RNAs. These data place the noncoding RNAs upstream of TNF gene as central to the transcriptional regulation. They appear to serve as a platform for the assembly of a repressive complex.

Anti-inflammation of spirocyclopiperazinium salt compound LXM-10 targeting α7 nAChR and M4 mAChR and inhibiting JAK2/STAT3 pathway in rats

The present study aims to investigate the therapeutic effects of LXM-10 by intragastric administration in both acute and chronic inflammatory models, and to explore the underlying molecular mechanisms. The results showed that LXM-10 produced significant anti-inflammatory effects on carrageenan induced paw edema and complete Freund's adjuvant (CFA) induced arthritis, in which LXM-10 inhibited paw swelling in a dose- and time-dependent manner. ELISA analysis showed the production of pro-inflammatory cytokines including TNF-α and IL-6 was decreased by LXM-10. Western blot analysis showed that LXM-10 significantly reduced phosphorylation of Janus kinase 2 (JAK2) and further blunted phosphorylation of signal transducer and activator of transcription-3 (STAT3). The effects that LXM-10 had shown were attenuated by methyllycaconitine citrate (an α7 nicotinic acetylcholine receptor antagonist) or tropicamide (an M4 muscarinic acetylcholine receptor antagonist) in vivo. In conclusion, the studies showed that intragastric administration of LXM-10 exerted significant anti-inflammation effects in acute and chronic models, which may be attribute to the activation of α7 nicotinic acetylcholine receptor and M4 muscarinic acetylcholine receptor, thereby inhibiting the JAK2/STAT3 signal pathway, and ultimately reducing the production of pro-inflammatory cytokines of TNF-α and IL-6.

Role of epigenetics in inflammation-associated diseases

There is considerable evidence suggesting that epigenetic mechanisms may mediate development of chronic inflammation by modulating the expression of pro-inflammatory cytokine TNF-α, interleukins, tumor suppressor genes, oncogenes and autocrine and paracrine activation of the transcription factor NF-κB. These molecules are constitutively produced by a variety of cells under chronic inflammatory conditions, which in turn leads to the development of major diseases such as autoimmune disorders, chronic obstructive pulmonary diseases, neurodegenerative diseases and cancer. Distinct or global changes in the epigenetic landscape are hallmarks of chronic inflammation driven diseases. Epigenetics include changes to distinct markers on the genome and associated cellular transcriptional machinery that are copied during cell division (mitosis and meiosis). These changes appear for a short span of time and they necessarily do not make permanent changes to the primary DNA sequence itself. However, the most frequently observed epigenetic changes include aberrant DNA methylation, and histone acetylation and deacetylation. In this chapter, we focus on pro-inflammatory molecules that are regulated by enzymes involved in epigenetic modifications such as arginine and lysine methyl transferases, DNA methyltransferase, histone acetyltransferases and histone deacetylases and their role in inflammation driven diseases. Agents that modulate or inhibit these epigenetic modifications, such as HAT or HDAC inhibitors have shown great potential in inhibiting the progression of these diseases. Given the plasticity of these epigenetic changes and their readiness to respond to intervention by small molecule inhibitors, there is a tremendous potential for the development of novel therapeutics that will serve as direct or adjuvant therapeutic compounds in the treatment of these diseases.

JAK2 inhibition prevents innate immune responses and rescues animals from sepsis

Sepsis, a leading cause of death in hospitalized patients, is characterized by lethal systemic inflammatory responses. JAK2 is an essential tyrosine kinase modulating immune responses. However, the implications of JAK2 in infectious disorders remain undetermined. Here, we report that JAK2 inhibitors rescue animals from polymicrobial sepsis in a clinically relevant time frame. JAK2 inhibition with AG490 prevents NF-kappaB activation, modulates macrophage activation, and restrains the production of inflammatory cytokines. The inhibition of JAK2 blunted TNF production in both macrophages and splenocytes in a concentration-dependent manner. JAK2 inhibition specifically prevents LPS-induced STAT3 tyrosine phosphorylation without affecting serine phosphorylation in macrophages. JAK2 inhibitor prevents the activation of the canonical p65RelA/p50NF-kappaB1 pathway but not the other NF-kappaB proteins. In vivo, JAK2 inhibition restrains serum TNF levels by modulating TNF production in the lung and the spleen and protects mice from lethal endotoxemia in a concentration-dependent manner. AG490 also inhibits extracellular release of HMGB1 from macrophages and prevents an increase in serum HMGB1 levels during sepsis. JAK2 inhibition started at 24 h after the onset of sepsis rescued the mice from polymicrobial sepsis. Our study is the first experimental evidence that JAK2 inhibitors may provide a pharmacological advantage for the treatment of sepsis in a clinically relevant time frame.

Tumor necrosis factor-a augments lipopolysaccharide-induced suppressor of cytokine signalling 3 (SOCS-3) protein expression by preventing the degradation

The regulatory role of tumour necrosis factor-a (TNF-a) on the expression of suppressor of cytokine signalling 3 (SOCS-3) in response to lipopolysaccharide (LPS) was examined using peritoneal macrophages from TNF-a-deficient mice. The LPS-induced SOCS-3 expression was markedly augmented in macrophages from wild-type mice whereas such augmentation was not seen in the cells from TNF-a-deficient mice. However, there was no significant difference in the level of SOCS-3 messenger RNA expression between macrophages from wild-type mice and those from TNF-a-deficient mice. The addition of exogenous TNF-a augmented the LPS-induced SOCS-3 expression in macrophages from TNF-a-deficient mice. The pulse chase analysis suggested augmented degradation of LPS-induced SOCS-3 protein in macrophages from TNF-a-deficient mice. Moreover, MG 132, a 26S proteasome inhibitor, sustained the LPS-induced SOCS-3 expression in those cells. The tyrosine phosphorylation of SOCS-3 was definitely induced in LPS-stimulated macrophages from TNF-a-deficient mice but not wild-type mice. A tyrosine phosphatase inhibitor enhanced the tyrosine phosphorylation of SOCS-3 in wild-type mice and accelerated the degradation. Therefore, it was suggested that TNF-a prevented the degradation of SOCS-3 protein via inhibition of the tyrosine phosphorylation in LPS-stimulated macrophages.

Neutralization of TNFalpha alters inflammation in guinea pig tuberculous pleuritis

Previously, treatment with anti-gpTNFalpha antibody enhanced TNFalpha mRNA expression in pulmonary granulomas microdissected from non-vaccinated guinea pigs, and modified splenic granuloma architecture. In this study, pleural fluid, cells, and granulomatous tissues were collected 3, 5, and 8 days post-pleurisy induction in guinea pigs treated with anti-gpTNFalpha or normal serum control. Neutralizing TNFalpha reduced the percentage of macrophages in the pleural exudate while increasing the proportions of neutrophils and lymphocytes. Cell-associated mycobacterial loads were increased in guinea pigs treated with anti-gpTNFalpha antibody. Cells from the pleural exudate in both treatment groups at day 3 expressed predominantly TNFalpha and IFNgamma mRNA. By day 5, treatment with anti-gpTNFalpha antibody significantly reduced TNFalpha mRNA and increased TGFbeta and iNOS mRNA expression, a transition which did not occur in the control group until day 8. TNFalpha mRNA overwhelmed the cytokine milieu of microdissected pleural granulomas in the control group at day 3 whereas TNFalpha, IFNgamma, and TGFbeta mRNA dominated the anti-gpTNFalpha-treated group. At day 8, granulomas from the control group began shifting towards an anti-inflammatory profile with increased levels of TGFbeta mRNA. Neutralization of TNFalpha hastened the transition to an anti-inflammatory cytokine response in guinea pig pleural granulomas and exudate cells.

Polarization of primary human monocytes by IFN-gamma induces chromatin changes and recruits RNA Pol II to the TNF-alpha promoter

Monocyte polarization by IFN-gamma or IL-4 drives a complex series of cellular responses leading to increased intracellular killing (IFN-gamma) or enhanced healing (IL-4) among other functional responses. We studied the effect of IL-4 and IFN-gamma polarization on histone modifications at the TNF-alpha locus in human primary monocytes. IFN-gamma polarization markedly increased the expression of TNF-alpha, whereas IL-4 treatment decreased the expression. We found that IFN-gamma alone increased histone H4 acetylation at the TNF-alpha promoter. The effect of IFN-gamma on TNF-alpha expression was durable upon cytokine washout and even repolarization with IL-4. Concordantly, IFN-gamma-mediated H4 acetylation was also durable. IFN-gamma recruited activating transcription factor-2 via p38 to the TNF-alpha promoter, but inhibition of p38 had minimal effect on H4 acetylation. In a novel finding, we found that IFN-gamma recruited RNA Pol II to the human TNF-alpha promoter via ERK signaling, but did so without initiating transcription, leading to a poised condition. These studies provide an important perspective on monocyte polarization. Polarization by IFN-gamma has a durable effect on TNF-alpha expression, and histone acetylation may provide a mechanism for persistence of the effect.

Epigenetic regulation of tumor necrosis factor alpha

Tumor necrosis factor alpha (TNF-alpha) is a potent cytokine which regulates inflammation via the induction of adhesion molecules and chemokine expression. Its expression is known to be regulated in a complex manner with transcription, message turnover, message splicing, translation, and protein cleavage from the cell surface all being independently regulated. This study examined both cell lines and primary cells to understand the developmental regulation of epigenetic changes at the TNF-alpha locus. We demonstrate that epigenetic modifications of the TNF-alpha locus occur both developmentally and in response to acute stimulation and, importantly, that they actively regulate expression. DNA demethylates early in development, beginning with the hematopoietic stem cell. The TNF-alpha locus migrates from heterochromatin to euchromatin in a progressive fashion, reaching euchromatin slightly later in differentiation. Finally, histone modifications characteristic of a transcriptionally competent gene occur with myeloid differentiation and progress with differentiation. Additional histone modifications characteristic of active gene expression are acquired with stimulation. In each case, manipulation of these epigenetic variables altered the ability of the cell to express TNF-alpha. These studies demonstrate the importance of epigenetic regulation in the control of TNF-alpha expression. These findings may have relevance for inflammatory disorders in which TNF-alpha is overproduced.

Modulation of TNF-alpha gene expression by IFN-gamma and pamidronate in murine macrophages: regulation by STAT1-dependent pathways

Aminobisphosphonates are drugs used in the treatment of hypercalcemia, Paget's disease, osteoporosis, and malignancy. Some patients treated with aminobisphosphonates have a transient febrile reaction that may be caused by an increased serum concentration of proinflammatory cytokines. Aminobisphosphonates induce the production of certain proinflammatory cytokines in vitro, especially in cells of monocytic lineage. A unique feature of aminobisphosphonates is that they bind the Vgamma2Vdelta2 class of T cells, which are found only in primates, and stimulate cytokine production. The effects of aminobisphosphonates on other cells, including macrophages, are incompletely understood. We show in this study that treatment of murine macrophages with pamidronate, a second generation aminobisphosphonate, induces TNF-alpha production. Furthermore, pretreatment of murine macrophages with pamidronate before stimulation with IFN-gamma significantly augments IFN-gamma-dependent production of TNF-alpha. This pamidronate-mediated augmentation of TNF-alpha production results in sustained phosphorylation of the tyrosine residue at position 701 of STAT1 after IFN-gamma treatment. Our data suggest that this sustained phosphorylation results from inhibition of protein tyrosine phosphatase activity. We also show that pamidronate treatment increases TNF-alpha production in vivo in mice. Pamidronate-augmented TNF-alpha production by macrophages might be a useful strategy for cytokine-based anticancer therapy.

Regulation of inflammation

Inflammation is part of the response to infection. It is often considered to be part of the innate response to infection, but it plays a significant role in molding the adaptive response. Conserved pathways that have evolved to contain the infection and mold the ensuing adaptive response can cause deleterious effects when dysregulated. In this review, the various roles of TNFalpha will be discussed. Its pleomorphic effects require complex regulatory strategies. Our work has focused on the role of TNFalpha in autoimmune diseases and the regulation of its expression by transcription factors and chromatin remodeling.

Kinetics of a gamma interferon response: expression and assembly of CIITA promoter IV and inhibition by methylation

Chromatin immunoprecipitation assays were employed to assess the kinetics of transcription factor assembly and histone modifications that occur during gamma interferon (IFN-gamma) induction of CIITA gene expression. CIITA is the master regulator of major histocompatibility complex class II transcription. Promoter IV (PIV), the major IFN-gamma responsive promoter for CIITA expression, requires both STAT1 and IFN regulatory factor 1 (IRF-1) for induction by IFN-gamma. STAT1 binding to PIV was detected first and was accompanied by a modest acetylation of histones H3 and H4 that were associated with the region. Despite these changes, which occurred within 30 min of IFN-gamma treatment, CIITA mRNA was not detected until IRF-1 protein was synthesized and bound to its site, a process that required >120 min. In contrast to these events, fetal trophoblast-like cell lines, which are refractory to CIITA induction by IFN-gamma, failed to assemble the above factors or modify their chromatin, suggesting that accessibility to the promoter is blocked. Bisulfite sequencing of PIV showed strong hypermethylation of PIV, providing a link between methylation, chromatin structure, and factor binding. Together, this analysis provides a kinetic view of the activation of the CIITA gene in response to IFN-gamma and shows that regulatory factor assembly, chromatin modification, and gene expression proceed in discrete steps.