Key inflammatory signaling pathways are regulated by the proteasome

The preliminary study suggests an association between NF-ĸB pathway activation and increased plasma 20S proteasome activity in intracranial aneurysm patients

The significant role of increased activation of 20S proteasomes in the development of abdominal aortic aneurysms has been well-established in a mouse model. The available literature lacks similar studies concerning brain aneurysms. The aim of the study was to verify the hypothesis that patients with unruptured intracranial aneurysms (UIA) have increased 20S proteasome ChT-L activity compared to the control group of individuals without vascular lesions in the brain. In the next step, the relationship between the activity of 20S proteasomes ChT-L and precursor proteins from the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) family, namely NF-κB1 (p105), NF-κB2 (p100), NF-κB p65, and the inflammatory chemokine MCP-1, was examined. Patients with UIA had significantly higher 20S ChT-L proteasome activity compared to the control group. Patients with multiple aneurysms had significantly higher 20S proteasome ChT-L activity compared to those with single aneurysms. In patients with UIA, the activity of the 20S proteasome ChT-L negatively correlated with the concentration of NF-κB1 (p105) and NF-κB p65 precursor proteins and positively correlated with the concentration of the cerebrospinal fluid chemokine MCP-1. Our results may suggest that increased 20S proteasome ChT-L activity in UIA patients modulates inflammation in the cerebral arterial vessel via the MCP-1 chemokine as a result of activation of the canonical NF-κB pathway.

Crosstalk between phytochemicals and inflammatory signaling pathways

Novel bioactive constituents from natural sources are actively being investigated. The phytochemicals in these phenolic compounds are believed to have a variety of beneficial effects on human health. Several phenolic compounds have been found in plants. The antioxidant potential of phenols has been discussed in numerous studies along with their anti-inflammatory effects on pro-inflammatory cytokine, inducible cyclooxygenase-2, and nitric oxide synthase. Through current study, an attempt is made to outline and highlight a wide variety of inflammation-associated signaling pathways that have been modified by several natural compounds. These signaling pathways include nuclear factor-kappa B (NF-кB), activator protein (AP)-1, protein tyrosine kinases (PTKs), mitogen-activated protein kinases (MAPKs), nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factors, tyrosine phosphatidylinositol 3-kinase (PI3K)/AKT, and the ubiquitin-proteasome system. In light of the influence of natural substances on signaling pathways, their impact on the production of inflammatory mediator is highlighted in this review.

Dysregulation of Gene Expression of Key Signaling Mediators in PBMCs from People with Type 2 Diabetes Mellitus

Diabetes is currently the fifth leading cause of death by disease in the USA. The underlying mechanisms for type 2 Diabetes Mellitus (DM2) and the enhanced susceptibility of such patients to inflammatory disorders and infections remain to be fully defined. We have recently shown that peripheral blood mononuclear cells (PBMCs) from non-diabetic people upregulate expression of inflammatory genes in response to proteasome modulators, such as bacterial lipopolysaccharide (LPS) and soybean lectin (LEC); in contrast, resveratrol (RES) downregulates this response. We hypothesized that LPS and LEC will also elicit a similar upregulation of gene expression of key signaling mediators in (PBMCs) from people with type 2 diabetes (PwD2, with chronic inflammation) ex vivo. Unexpectedly, using next generation sequencing (NGS), we show for the first time, that PBMCs from PwD2 failed to elicit a robust LPS- and LEC-induced gene expression of proteasome subunit LMP7 (PSMB8) and mediators of T cell signaling that were observed in non-diabetic controls. These repressed genes included: PSMB8, PSMB9, interferon-γ, interferon-λ, signal-transducer-and-activator-of-transcription-1 (STAT1), human leukocyte antigen (HLA DQB1, HLA DQA1) molecules, interleukin 12A, tumor necrosis factor-α, transporter associated with antigen processing 1 (TAP1), and several others, which showed a markedly weak upregulation with toxins in PBMCs from PwD2, as compared to those from non-diabetics. Resveratrol (proteasome inhibitor) further downregulated the gene expression of these inflammatory mediators in PBMCs from PwD2. These results might explain why PwD2 may be susceptible to infectious disease. LPS and toxins may be leading to inflammation, insulin resistance, and thus, metabolic changes in the host cells.

A Novel Mechanism of Immunoproteasome Regulation via miR-369-3p in Intestinal Inflammatory Response

The immunoproteasome is a multi-catalytic protein complex expressed in hematopoietic cells. Increased expression of immuno-subunits followed by increased proteasome activities is associated with the pathogenesis of IBD. Therefore, the identification of molecules that could inhibit the activities of this complex has been widely studied. microRNAs are small molecules of non-coding RNA that regulate the expression of target genes. Our purpose was to demonstrate that miR-369-3p is able to reduce the expression of the PSMB9 subunit and consequently modulate the catalytic activities of immunoproteasome. After bioinformatics prediction of the gene target of miR-369-3p, we validated its modulation on PSMB9 expression in the RAW264.7 cell line in vitro. We also found that miR-369-3p indirectly reduced the expression of other immunoproteasome subunits and that this regulation reduced the catalytic functions of the immunoproteasome. Increased levels of PSMB9 were observed in colon samples of acute IBD patients compared to the remission IBD group and control group. Our data suggest that miR-369-3p may be a future alternative therapeutic approach to several compounds currently used for the treatment of inflammatory disorders including IBD.

Reprograming of Gene Expression of Key Inflammatory Signaling Pathways in Human Peripheral Blood Mononuclear Cells by Soybean Lectin and Resveratrol

Inflammation is linked to several human diseases like microbial infections, cancer, heart disease, asthma, diabetes, and neurological disorders. We have shown that the prototype inflammatory agonist LPS modulates the activity of Ubiquitin-Proteasome System (UPS) and regulates transcription factors such as NF-κB, leading to inflammation, tolerance, hypoxia, autophagy, and apoptosis of cells. We hypothesized that proteasome modulators resveratrol and soybean lectin would alter the gene expression of mediators involved in inflammation-induced signaling pathways, when administered ex vivo to human peripheral blood mononuclear blood cells (PBMCs) obtained from normal healthy controls. To test this hypothesis, analysis of RNA derived from LPS-treated human PBMCs, with or without resveratrol and soybean lectin, was carried out using Next Generation Sequencing (NGS). Collectively, the findings described herein suggest that proteasome modulators, resveratrol (proteasome inhibitor) and lectins (proteasome activator), have a profound capacity to modulate cytokine expression in response to proteasome modulators, as well as expression of mediators in multiple signaling pathways in PBMCs of control subjects. We show for the first-time that resveratrol downregulates expression of mediators involved in several key signaling pathways IFN-γ, IL-4, PSMB8 (LMP7), and a subset of LPS-induced genes, while lectins induced IFN-γ, IL-4, PSMB8, and many of the same genes as LPS that are important for innate and adaptive immunity. These findings suggest that inflammation may be influenced by common dietary components and this knowledge may be used to prevent or reverse inflammation-based diseases.

Understanding the Interplay Between Health Disparities and Epigenomics

Social epigenomics has emerged as an integrative field of research focused on identification of socio-environmental factors, their influence on human biology through epigenomic modifications, and how they contribute to current health disparities. Several health disparities studies have been published using genetic-based approaches; however, increasing accessibility and affordability of molecular technologies have allowed for an in-depth investigation of the influence of external factors on epigenetic modifications (e.g., DNA methylation, micro-RNA expression). Currently, research is focused on epigenetic changes in response to environment, as well as targeted epigenetic therapies and environmental/social strategies for potentially minimizing certain health disparities. Here, we will review recent findings in this field pertaining to conditions and diseases over life span encompassing prenatal to adult stages.

H2S counteracts proinflammatory effects of LPS through modulation of multiple pathways in human cells

BACKGROUND

Hydrogen sulfide donors reduce inflammatory signaling in vitro and in vivo. The biological effect mediated by H₂S donors depends on the kinetics of the gas release from the donor molecule. However, the molecular mechanisms of H₂S-induced immunomodulation were poorly addressed. Here, we studied the effect of two different hydrogen sulfide (H₂S)-producing agents on the generation of the LPS-induced inflammatory mediators. Importantly, we investigated the transcriptomic changes that take place in human cells after the LPS challenge, combined with the pretreatment with a slow-releasing H₂S donor-GYY4137.

METHODS

We investigated the effects of GYY4137 and sodium hydrosulfide on the release of proinflammatory molecules such as ROS, NO and TNF-α from LPS-treated human SH-SY5Y neuroblastoma and the THP-1 promonocytic cell lines. Transcriptomic and RT-qPCR studies using THP-1 cells were performed to monitor the effects of the GYY4137 on multiple signaling pathways, including various immune-related and proinflammatory genes after combined action of LPS and GYY4137.

RESULTS

The GYY4137 and sodium hydrosulfide differed in the ability to reduce the production of the LPS-evoked proinflammatory mediators. The pre-treatment with GYY4137 resulted in a drastic down-regulation of many TNF-α effectors that are induced by LPS treatment in THP-1 cells. Furthermore, GYY4137 pretreatment of LPS-exposed cells ameliorates the LPS-mediated induction of multiple pro-inflammatory genes and decreases expression of immunoproteasome genes. Besides, in these experiments we detected the up-regulation of several important pathways that are inhibited by LPS.

CONCLUSION

Based on the obtained results we believe that our transcriptomic analysis significantly contributes to the understanding of the molecular mechanisms of anti-inflammatory and cytoprotective activity of hydrogen sulfide donors, and highlights their potential against LPS challenges and other forms of inflammation.

Toddalolactone Protects Lipopolysaccharide-Induced Sepsis and Attenuates Lipopolysaccharide-Induced Inflammatory Response by Modulating HMGB1-NF-κB Translocation

Toddalolactone (TA-8) is a main compound isolated from Toddalia asiatica (L.) Lam., and its anti-inflammatory activity and anti-inflammatory mechanism are less studied. In the present study, we investigated the anti-inflammatory effects of TA-8. Our experimental results showed that TA-8 inhibited the production of pro-inflammatory cytokines by both lipopolysaccharide (LPS)-activated RAW 264.7 cells and septic mice. Moreover, TA-8 suppressed the NF-κB transcriptional activity, reduced the nuclear translocation and phosphorylation of NF-κB, blocked the translocation of HMGB1 from the nucleus to cytosol, and decreased LPS-induced up-regulation of TLR4 and IKBKB expression, and decreased IκBα phosphorylation. In addition, the administration of TA-8 decreased LPS-induced liver damage markers (AST and ALT), attenuated infiltration of inflammatory cells and tissue damage of lung, liver, and kidney, and improved survival in septic mice. Taken together, these results suggested that toddalolactone protects LPS-induced sepsis and attenuates LPS-induced inflammatory response by modulating HMGB1-NF-κB translocation. TA-8 could potentially be a novel anti-inflammatory and immunosuppressive drug candidate in the treatment of sepsis and septic shock.

Resveratrol Downregulates Biomarkers of Sepsis Via Inhibition of Proteasome's Proteases

Lipopolysaccharide (LPS) is the main agonist of gram-negative bacteria and initiates inflammation. We recently reported that plasmas from sepsis patients revealed increased levels of following group of biomarkers; VCAM-1, ICAM1, CRP, resistin, and proteasome LMP subunits. Our objective here was to compare effects of resveratrol (shown to be a nonspecific proteasome inhibitor by us) and a known LMP7 inhibitor (ONX-0914, specific inhibitor) on proteasome's activities, as well as on inflammatory markers mentioned above in human blood monocytes. Using fluorescence-based assays on blood monocytes purified proteasomes, resveratrol (0-100 μM) inhibited all three protease activities, predominantly LMP7. Similarly, resveratrol inhibited all three protease activities using cell-based luminescence assay. In contrast, ONX-0914 was more selective and potent for LMP7 activity. Resveratrol and ONX-0914, both significantly inhibited expression of LPS-induced biomarkers mentioned above in CD14 monocytes. Moreover, resveratrol itself, as well as in combination with LPS, accumulated pIκBα in CD14 monocytes. Collectively, our data suggest that resveratrol is a less potent inhibitor of all three; CT-like (predominantly LMP7), T-like and PA protease activities and is less toxic to human monocytes than ONX-0914 (a selector inhibitor of only LMP7) as observed by an autophagy detection kit. Also, resveratrol reduces LPS-induced inflammatory cytokine expression by decreasing the translocation of NF-κB due to an increase in inhibitor pIκBα. Therefore, resveratrol can be used to curb inflammation in diseased states like sepsis and other disorders.

A Marine Diterpenoid Modulates the Proteasome Activity in Murine Macrophages Stimulated with LPS

The proteasome is an intracellular complex that degrades damaged or unfolded proteins and participates in the regulation of several processes. The immunoproteasome is a specialized form that is expressed in response to proinflammatory signals and is particularly abundant in immune cells. In a previous work, we found an anti-inflammatory effect in a diterpenoid extracted from the octocoral Pseudopterogorgia acerosa, here called compound 1. This compound prevented the degradation of inhibitor κB α (IκBα) and the subsequent activation of nuclear factor κB (NFκB), suggesting that this effect might be due to inhibition of the ubiquitin-proteasome system. Here we show that compound 1 inhibits the proteasomal chymotrypsin-like activity (CTL) of murine macrophages in the presence of lipopolysaccharide (LPS) but not in its absence. This effect might be due to the capacity of this compound to inhibit the activity of purified immunoproteasome. The compound inhibits the cell surface expression of major histocompatibility complex (MHC)-I molecules and the production of proinflammatory cytokines induced by LPS in vitro and in vivo, respectively. Molecular docking simulations predicted that compound 1 selectively binds to the catalytic site of immunoproteasome subunits β1i and β5i, which are responsible for the CTL activity. Taken together these findings suggest that the compound could be a selective inhibitor of the immunoproteasome, and hence could pave the way for its future evaluation as a candidate for the treatment of inflammatory disorders and autoimmune diseases.

Proteasome inhibitors modulate anticancer and anti-proliferative properties via NF-kB signaling, and ubiquitin-proteasome pathways in cancer cell lines of different organs

BACKGROUND

Cancer is second most common cause of death in the United State. There are over 100 different types of cancer associated with different human organs, predominantly breast, liver, pancreas, prostate, colon, rectum, lung, and stomach. We have recently reported properties of pro-inflammatory (for treatment of various types of cancers), and anti-inflammatory (for cardiovascular disease and diabetes) compounds. The major problem associated with development of anticancer drugs is their lack of solubility in aqueous solutions and severe side effects in cancer patients. Therefore, the present study was carried out to check anticancer properties of selected compounds, mostly aqueous soluble, in cancer cell lines from different organs.

METHODS

The anticancer properties, anti-proliferative, and pro-apoptotic activity of novel naturally occurring or FDA approved, nontoxic, proteasome inhibitors/activators were compared. In addition to that, effect of δ-tocotrienol on expression of proteasome subunits (X, Y, Z, LMP7, LMP2, LMP10), ICAM-1, VCAM-1, and TNF-α using total RNAs derived from plasmas of hepatitis C patients was investigated.

RESULTS

Our data demonstrated that following compounds are very effective in inducing apoptosis of cancer cells: Thiostrepton, dexamethasone, 2-methoxyestradiol, δ-tocotrienol, quercetin, amiloride, and quinine sulfate have significant anti-proliferation properties in Hela cells (44% - 87%) with doses of 2.5-20 μM, compared to respective controls. Anti-proliferation properties of thiostrepton, 2-methoxyestradiol, δ-tocotrienol, and quercetin were 70% - 92%. However, thiostrepton, dexamethasone, 2-methoxyestradiol, δ-tocotrienol, quercetin, and quinine sulphate were effective in pancreatic, prostate, breast, lungs, melanoma, Β-lymphocytes, and T-cells (Jurkat: 40% to 95%) compared to respective controls. In lung cancer cells, these compounds were effective between 5 and 40 μM. The IC₅₀ values of anti-proliferation properties of thiostrepton in most of these cell lines were between doses of 2.5-5 μM, dexamethasone 2.5-20 μM, 2-methoxyestradiol 2.5-10 μM, δ-tocotrienol 2.5-20 μM, quercetin 10-40 μM, and (-) Corey lactone 40-80 μM. In hepatitis C patients, δ-tocotrienol treatment resulted in significant decrease in the expression of pro-inflammatory cytokines.

CONCLUSIONS

These data demonstrate effectiveness of several natural-occurring compounds with anti-proliferative properties against cancer cells of several organs of humans. Thiostrepton, dexamethasone, 2-methoxyestradiol, δ-tocotrienol and quercetin are very effective for apoptosis of cancer cells in liver, pancreas, prostate, breast, lung, melanoma, Β-lymphocytes and T-cells. The results have provided an opportunity to test these compounds either individually or in combination as dietary supplements in humans for treatment of various types of cancers.

Of Mice and Men: Proteasome's Role in LPS-Induced Inflammation and Tolerance

The molecular basis responsible for tolerance following inflammatory response to lipopolysaccharide (LPS) is not well understood. We hypothesized that inflammation/tolerance in monocytes/ macrophages is dependent on the proteases of proteasome. To test our hypothesis, first, we examined the expression of different proteasome subunits in different human and mouse monocytes/macrophages. Secondly, we investigated the effect of proteasome subunits/ proteases on LPS-induced expression of tumor necrosis factor-α (TNF-α) and nitric oxide (NO) during inflammation and tolerance using mouse RAW 264.7 macrophages, THP1 cells, and cluster of differentiation 14 positive (CD14) human monocytes. We found that RAW 264.7 cells (XYZ), mouse peritoneal resident, thioglycollate-elicited macrophages, primed RAW 264.7 (XYZ, LMP), and human monocytes (LMP) expressed different types of proteasome subunits/activities. Cells containing predominantly either LMP subunits (such as THP-1 and human monocytes), or only X, Y, Z subunits (RAW 264.7 cells not primed) could only induce TNF-α, but not NO, while cells containing all five to six subunits (XYZ, LMP) of the proteasome could induce both mediators in response to LPS. Distinct states of inflammation/tolerance in LPS treated cells, strongly correlated with an upregulation or downregulation of proteasome's subunits (proteases), respectively. Moreover, interferon-γ treatment of tolerant cells caused robust induction of proteasome's subunit expression in mouse macrophages and human monocytes, and cells regained their ability to respond to LPS. These studies are vital for understanding function of proteasome's subunits during inflammation/tolerance in mouse and human cells, and for design of therapeutic strategies for all diseases based on inflammation.

The role of the immunoproteasome in interferon-γ-mediated microglial activation

Microglia regulate the brain microenvironment by sensing damage and neutralizing potentially harmful insults. Disruption of central nervous system (CNS) homeostasis results in transition of microglia to a reactive state characterized by morphological changes and production of cytokines to prevent further damage to CNS tissue. Immunoproteasome levels are elevated in activated microglia in models of stroke, infection and traumatic brain injury, though the exact role of the immunoproteasome in neuropathology remains poorly defined. Using gene expression analysis and native gel electrophoresis we characterize the expression and assembly of the immunoproteasome in microglia following interferon-gamma exposure. Transcriptome analysis suggests that the immunoproteasome regulates multiple features of microglial activation including nitric oxide production and phagocytosis. We show that inhibiting the immunoproteasome attenuates expression of pro-inflammatory cytokines and suppresses interferon-gamma-dependent priming of microglia. These results imply that targeting immunoproteasome function following CNS injury may attenuate select microglial activity to improve the pathophysiology of neurodegenerative conditions or the progress of inflammation-mediated secondary injury following neurotrauma.

Age influences inflammatory responses, hemodynamics, and cardiac proteasome activation during acute lung injury

BACKGROUND

Acute lung injury (ALI) is a significant source of morbidity and mortality in critically ill patients. Age is a major determinant of clinical outcome in ALI. The increased ALI-associated mortality in the older population suggests that there are age-dependent alterations in the responses to pulmonary challenge. The objective of this observational study was to evaluate age-dependent differences in the acute (within 6 hours) immunological and physiological responses of the heart and lung, to pulmonary challenge, that could result in increased severity.

METHODS

Male C57Bl/6 mice (young: 2-3 months, old: 18-20 months) were challenged intratracheally with cell wall components from Gram-positive bacteria (lipoteichoic acid and peptidoglycan). After 6 hours, both biochemical and physiological consequences of the challenge were assessed. Alveolar infiltration of inflammatory cells and protein, airspace and blood cytokines, cardiac function and myocardial proteasome activity were determined.

RESULTS

In young mice, there was a dose-dependent response to pulmonary challenge resulting in increased airspace neutrophil counts, lung permeability, and concentrations of cytokines in bronchoalveolar lavage fluid and plasma. A midrange dose was then selected to compare the responses in young and old animals. In comparison, the old animals displayed increased neutrophil accumulation in the airspaces, decreased arterial oxygen saturation, body temperatures, plasma cytokine concentrations, and a lack of myocardial proteasome response, following challenge.

CONCLUSIONS

Age-dependent differences in the onset of systemic response and in maintenance of vital functions, including temperature control, oxygen saturation, and myocardial proteasome activation, are evident. We believe a better understanding of these age-related consequences of ALI can lead to more appropriate treatments in the elderly patient population.

Roles of Toll-Like Receptor 4, IκB Kinase, and the Proteasome in the Intestinal Alterations Caused by Sepsis

BACKGROUND

Lipopolysaccharide decreases intestinal contractility and induces the production of cytokines, which play an important role in the pathogenesis of sepsis.

AIM

The objective of the present study was to examine the role of Toll-like receptor 4, IκB kinase, and the proteasome in the intestinal alterations induced by lipopolysaccharide.

METHODS

Sepsis was induced in rabbits by intravenous injection of lipopolysaccharide. Contractility studies of rabbit duodenum were performed in an organ bath. Expressions of interleukin-1β, interleukin-6, interleukin-8, interleukin-10, IκB kinase-α, IκB kinase-β, IκB kinase-γ, and the proteasome mRNA were determined by RT-PCR on rabbit duodenum.

RESULTS

Neomycin and polymyxin B (Toll-like receptor 4 inhibitors), IKK NBD peptide (IκB kinase complex inhibitor), and MG-132 (proteasome inhibitor) blocked partially the effects of lipopolysaccharide on the acetylcholine-, prostaglandin E2-, substance P-, and KCl-induced contractions in the longitudinal and circular smooth muscle of rabbit duodenum. Lipopolysaccharide increased the mRNA expression of interleukin-6 and interleukin-8 in duodenal tissue, and this effect was partly reversed by neomycin, polymyxin B, IKK NBD peptide, and MG-132. IκB kinase-α, IκB kinase-β, IκB kinase-γ, and the proteasome mRNA expressions was not affected by lipopolysaccharide treatment.

CONCLUSIONS

Toll-like receptor 4, the IκB kinase complex, and the proteasome could be therapeutic targets in the treatment of sepsis symptoms in the intestine.

[Features of immune proteasome expression in the development of rat central nervous system]

Formation of the central nervous system in ontogeny and function in adult mammals are controlled by universal ubiquitin-proteasome proteolytic system. The aim of this work was to study the dynamics of expression of immune proteasomes in comparison with the dynamics of ChLA and CLA proteasome and expression of the transcription factor Zif268 in the structures of the brain (cortex, hippocampus, and brainstem) in embryonic (E19, E21 days of embryonic development) and early postnatal (P1, P3, P4, P5, P7, P15 days of post-natal development) development in rats. ChLA and CLA in clarified homogenates of rat brain structures were determined by hydrolysis of fluorogenic commercial oligopeptides Suc-LLVY-AMC and Z-LLG-AMC, respectively. In the cortex and hippocampus of the brain was observed upregulation of immune subunits LMP7 during the active formation of biochemical mediatory structure and efferent neuronal projections at the period P7-P15. In the cerebral cortex during this period ChLA and CLA also are increased. In all structures of the brain the LMP2 immune subunits content was significantly increased at the period P7-P15. Contents of proteolytic constitutive subunit β1 in all structures decreased by P4 compare to P1 levels and was increased on P15 relative to the P1 levels. However, the level of expression of proteolytic constitutive subunit β5 increased in cortex, hippocampus and brainstem from E21 and reached maximum values on P3, P5 and P1, respectively with a sharp decrease to P7 in all studied structures. In all structures expression of LM P2 immune subunits and β1 constitutive subunits increased simultaneously with LMP7 immune subunits and sharply on P15. Also shown a positive correlation of increased expression regulator PA28 and constitutive β5 subunits in the hippocampus during the period P3-P5 and in the brainstem at the period P1-P5. The peculiarity of the studied brain regions during P7-P15 of rat early development is a correlation of expression of immune subunits LMP2 and LMP7 proteasome and ChLA with the expression of the transcription factor Zif268. Probably immune proteasome plays an important role in the regulation of key biochemical processes in the early ontogenesis of the central nervous system and are necessary for the emergence and realization of synaptic plasticity in the brain structures studied in rats.

The effect of bortezomib on expression of inflammatory cytokines and survival in a murine sepsis model induced by cecal ligation and puncture

PURPOSE

Although the proteasome inhibitor known as bortezomib can modulate the inflammatory process through the nuclear factor-kappa B signaling pathway, the immunomodulatory effect of pre-incubated bortezomib has not been fully evaluated for inflammation by infectious agents. Therefore, we evaluated the effect of bortezomib on the expression of inflammatory cytokines and mediators in macrophage cell lines and on survival in a murine peritonitis sepsis model.

MATERIALS AND METHODS

Bortezomib was applied 1 hr before lipopolysaccharide (LPS) stimulation in RAW 264.7 cells. The cecal ligation and puncture (CLP) experiments were performed in C57BL/6J mice.

RESULTS

Pre-incubation with bortezomib (25 nM or 50 nM) prior to LPS (50 ng/mL or 100 ng/mL) stimulation significantly recovered the number of viable RAW 264.7 cells compared to those samples without pre-incubation. Bortezomib decreased various inflammatory cytokines as well as nitric oxide production in LPS-stimulated cells. The 7-day survival rate in mice that had received bortezomib at 0.01 mg/kg concentration 1 hr prior to CLP was significantly higher than in the mice that had only received a normal saline solution of 1 mL 1 hr prior to CLP. In addition, the administration of bortezomib at 0.01 mg/kg concentration 1 hr before CLP resulted in a significant decrease in inflammation of the lung parenchyma. Collectively, pretreatment with bortezomib showed an increase in the survival rate and changes in the levels of inflammatory mediators.

CONCLUSION

These results support the possibility of pretreatment with bortezomib as a new therapeutic target for the treatment of overwhelming inflammation, which is a characteristic of severe sepsis.

Comparative genomics RNAi screen identifies Eftud2 as a novel regulator of innate immunity

The extent of the innate immune response is regulated by many positively and negatively acting signaling proteins. This allows for proper activation of innate immunity to fight infection while ensuring that the response is limited to prevent unwanted complications. Thus mutations in innate immune regulators can lead to immune dysfunction or to inflammatory diseases such as arthritis or atherosclerosis. To identify novel innate immune regulators that could affect infectious or inflammatory disease, we have taken a comparative genomics RNAi screening approach in which we inhibit orthologous genes in the nematode Caenorhabditis elegans and murine macrophages, expecting that genes with evolutionarily conserved function also will regulate innate immunity in humans. Here we report the results of an RNAi screen of approximately half of the C. elegans genome, which led to the identification of many candidate genes that regulate innate immunity in C. elegans and mouse macrophages. One of these novel conserved regulators of innate immunity is the mRNA splicing regulator Eftud2, which we show controls the alternate splicing of the MyD88 innate immunity signaling adaptor to modulate the extent of the innate immune response.

Generation and purification of highly specific antibodies for detecting post-translationally modified proteins in vivo

Post-translational modifications alter protein structure, affecting activity, stability, localization and/or binding partners. Antibodies that specifically recognize post-translationally modified proteins have a number of uses including immunocytochemistry and immunoprecipitation of the modified protein to purify protein-protein and protein-nucleic acid complexes. However, antibodies directed at modified sites on individual proteins are often nonspecific. Here we describe a protocol to purify polyclonal antibodies that specifically detect the modified protein of interest. The approach uses iterative rounds of subtraction and affinity purification, using stringent washes to remove antibodies that recognize the unmodified protein and low sequence complexity epitopes containing the modified amino acid. Dot blot and western blot assays are used to assess antibody preparation specificity. The approach is designed to overcome the common occurrence that a single round of subtraction and affinity purification is not sufficient to obtain a modified protein-specific antibody preparation. One full round of antibody purification and specificity testing takes 6 d of discontinuous time.

Anti-inflammatory activity of Cymbopogon citratus leaves infusion via proteasome and nuclear factor-κB pathway inhibition: contribution of chlorogenic acid

ETHNOPHARMACOLOGICAL RELEVANCE

Cymbopogon citratus (DC.) Stapf leaves infusion is used in traditional medicine for the treatment of inflammatory conditions, however little is known about their bioactive compounds.

AIM OF THE STUDY

Investigate the compounds responsible for anti-inflammatory potential of Cymbopogon citratus (Cy) on cytokines production induced by lipopolysaccharide (LPS) in human and mouse macrophages, and the action mechanisms involved.

MATERIALS AND METHODS

An essential oil-free infusion of Cy was prepared and polyphenol-rich fractions (PFs) were obtained from it by column chromatography. Chlorogenic acid (CGA) was identified, by HPLC/PDA/ESI-MS(n). The expression of cytokines, namely TNF-α and CCL5, was analyzed by real-time RT-PCR, on LPS-stimulated human macrophages. Activation of nuclear factor (NF)-κB, a master regulator of inflammation, was investigated by western blot and gene reporter assay. Proteasome activity was assessed using a fluorogenic peptide.

RESULTS

Cymbopogon citratus extract and its polyphenols inhibited the cytokine production on human macrophages. This supports the anti-inflammatory activity of Cy polyphenols in physiologically relevant cells. Concerning the effect on the activation of NF-κB pathway, the results pointed to an inhibition of LPS-induced NF-κB activation by Cy and PFs. CGA was identified, by HPLC/PDA/ESI-MS(n), as the main phenolic acid of the Cy infusion, and it demonstrated to be, at least in part, responsible by that effect. Additionally, it was verified for the first time that Cy and PFs inhibited the proteasome activity, a complex that controls NF-κB activation, having CGA a strong contribution.

CONCLUSIONS

The results evidenced, for the first time, the anti-inflammatory properties of Cymbopogon citratus through proteasome inhibition and, consequently NF-κB pathway and cytokine expression. Additionally, Cy polyphenols, in particular chlorogenic acid, were highlighted as bioactive compounds.

Proteasome inhibition decreases inflammation in human endothelial cells exposed to lipopolysaccharide

BACKGROUND

The proteasome degrades ubiquitinated proteins and is the major pathway for intracellular protein degradation. The role of the proteasome in endothelial dysfunction observed in septic shock remains unknown. We stimulated primary cultures of human umbilical vein endothelial cells with lipopolysaccharide (LPS) and investigated effects on the proteasome. We hypothesized that proteasome inhibition would decrease endothelial cell activation, oxidative stress, and alter the proteome.

METHODS

Endothelial cells were exposed to LPS (100 ng/mL) for 6 hours with or without lactacystin (5 mM), a proteasome inhibitor. Proteasome content and ubiquitinated proteins were measured by enzyme-linked immunosorbent assay and immunoblot, respectively. Markers of cellular activation, vascular cell adhesion molecule-1 and intercellular adhesion molecule-1, were measured by immunoblot and immunoassay. Superoxide anion production was determined by dihydroethidium assay, and nitrotyrosine (a marker of peroxynitrite) was visualized by immunofluoresence. The endothelial cell proteome was analyzed by 2D gel electrophoresis.

RESULTS

LPS stimulation of endothelial cells significantly increased proteasome content, whereas the total levels of ubquitinated proteins decreased. This suggests that LPS activates the proteasome system in endothelial cells. LPS increased total content and cell surface expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1, whereas proteasome inhibition ameliorated these increases. LPS increased both superoxide anion production and nitrotyrosine staining. Proteasome inhibition decreased both markers of cellular oxidative stress. Proteomic analysis identified two novel proteins upregulated by LPS and normalized with proteasome inhibition as follows: guanine nucleotide binding protein-1 and heterogeneous ribonucleoprotein K transcript variant.

CONCLUSIONS

These results suggest that inhibition of the proteasome diminishes a number of markers of cellular stress induced by LPS. The proteasome may be a promising therapeutic target in clinical situations of severe pro-inflammatory stress.

Nutritional Supplement-5 with a Combination of Proteasome Inhibitors (Resveratrol, Quercetin, δ-Tocotrienol) Modulate Age-Associated Biomarkers and Cardiovascular Lipid Parameters in Human Subjects

BACKGROUND

Age-associated altered redox imbalances and dysregulated immune function, contribute to the development of a variety of age associated diseases. Inflammatory markers and lipid profiles are useful prognostic indicators of a variety of age-associated and cardiovascular diseases. We have previously studied the impact of several proteasome inhibitors on several markers of inflammation and lipid profiles in vitro, in vivo, in cell lines, animal models, and in human subjects. The current study represents an extension of this work. Our main hypothesis is that a combination of various naturally-occurring proteasome inhibitors, which inhibits nitric oxide (NO), and C-reactive protein (CRP) mediated inflammation, will have better efficacy in the prevention and treatment of age-associated disorders including cardiovascular disease.

METHODS

Two double blind, randomized, placebo-controlled cross-over trials were conducted to determine the impact of a mixture of NS-5 (resveratrol, pterostilbene, quercetin, δ-tocotrienol, nicotinic acid) on serum NO, CRP, γ-glutamyl-transferase (γ-GT) activity, total antioxidant status (TAS), total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides levels. Healthy seniors (Group-1; n = 32) free-living (A, B; 16/group), and hypercholesterolemic (Group-2; n = 64) subjects on AHA-Step-1-diet were divided into two groups (C, D; 32/group). Baseline levels were established for parameters as mentioned above. Groups A, C were administered 4-capsules/d of NS-5 and groups B, D, placebo (starch) for 6-weeks. Groups were crossed-over, followed by a 2-week wash-out period. Groups A, C were given 4-capsules/d of placebo and groups B, D, 4-capsules/d of NS-5 for 6-weeks. Groups C, D were continued on AHA-Step-1-diet.

RESULTS

All the subjects completed each phase in both studies without any complaints. There were significant ( P < 0.01 - 0.05) decreases in the serum levels of NO (30%, 26%), CRP (29%, 21%), γ-GT activity (14%, 17%), and blood pressure (systolic/diastolic, 3/6%, 3/3%) of Groups A and B, respectively, of free-living healthy seniors without affecting the total, HDL-, LDL-cholesterol or triglycerides compared to their respective baseline values. However, serum levels of NO (36%, 43%), CRP (31%, 48%), γ-GT (17%, 20%), total cholesterol (19%, 15%), LDL-cholesterol (28%, 20%), triglycerides (11%, 18%) of Groups C and D were significantly ( P < 0.01-0.05) decreased with NS-5 treatment of hypercholesterolemic subjects compared to baseline values, without affecting the serum HDL-cholesterol levels. The serum levels of total antioxidant status (TAS) were increased (10%, 14%; P < 0.05) in Groups A and B, increased (19%, 24%; P < 0.02), and blood pressure (systolic/diastolic, 5/6%, 3/5%) in Groups C and D with NS-5 treatment, compared to respective baseline values.

CONCLUSIONS

The consumption of NS-5 mixture decreased significantly serum NO, CRP and γ-GT levels, improved TAS and lipid profiles at risk cardiovascular and hold promise for delaying onset of age-associated diseases.

Proteasome protease mediated regulation of cytokine induction and inflammation

We have previously demonstrated that proteasome serves as a central regulator of inflammation and macrophage function. Until recently, proteasomes have generally been considered to play a relatively passive role in the regulation of cellular activity, i.e., any ubiquitinated protein was considered to be in discriminatively targeted for degradation by the proteasome. We have demonstrated, however, by using specific proteasome protease inhibitors and knockout mice lacking specific components of immunoproteasomes, that proteasomes (containing X, Y, and Z protease subunits) and immunoproteasomes (containing LMP7, LMP2, and LMP10 protease subunits) have well-defined functions in cytokine induction and inflammation based on their individual protease activities. We have also shown that LPS-TLR mediated signaling in the murine RAW 264.7 macrophage cell line results in the replacement of macrophage immunoproteasomal subunits. Such modifications serve as pivotal regulators of LPS-induced inflammation. Our findings support the relatively novel concept that defects in structure/function of proteasome protease subunits caused by genetic disorders, aging, diet, or drugs may well have the potential to contribute to modulation of proteasome activity. Of particular relevance, we have identified quercetin and resveratrol, significant constituents present in berries and in red wine respectively, as two novel proteasome inhibitors that have been previously implicated as disease-modifying natural products. We posit that natural proteasome inhibitors/activators can potentially be used as therapeutic response modifiers to prevent/treat diseases through pathways involving the ubiquitin-proteasome pathway (UP-pathway), which likely functions as a master regulator involved in control of overall inflammatory responses. This article is part of a Special Issue entitled: Ubiquitin Drug Discovery and Diagnostics.

A critical role for the inducible proteasomal subunits LMP7 and MECL1 in cytokine production by activated murine splenocytes

BACKGROUND AND PURPOSE

The proteasome is a multi-subunit complex that proteolytically cleaves proteins. The replacement of the constitutive proteasome subunits β1, β2, and/or β5 with the IFNγ-inducible subunits LMP2, MECL1, and/or LMP7 results in the 'immunoproteasome'. The inducible subunits change the cleavage specificities of the proteasome, but it is unclear whether they have functions in addition to this. The purpose of the present study was to determine the role of the proteasome in general, as well as LMP7 and MECL1 specifically, with regard to cytokine production by activated primary splenocytes.

METHODS

A LMP7/MECL1-null mouse was engineered to determine the roles of these subunits in cytokine production. Isolated splenocytes from wild-type and LMP7/MECL1-/- mice were treated with lactacystin and activated with PMA and ionomycin and subsequently cytokine mRNA levels were quantified.

RESULTS

The present study demonstrates that LMP7/MECL1 regulates the expression of IFNγ, IL4, IL10, IL2Rβ, GATA3, and t-bet. In contrast, the regulation of IL2, IL13, TNFα, and IL2Rα by the proteasome appears to occur independently of LMP7/MECL1.

CONCLUSIONS

Collectively, the present study demonstrates that LMP7 and MECL1 regulate cytokine expression, suggesting this system represents a novel mechanism for the regulation of cytokines and cytokine signaling.

Inhibition of nitric oxide in LPS-stimulated macrophages of young and senescent mice by δ-tocotrienol and quercetin

Background

Changes in immune function believed to contribute to a variety of age-related diseases have been associated with increased production of nitric oxide (NO). We have recently reported that proteasome inhibitors (dexamethasone, mevinolin, quercetin, δ-tocotrienol, and riboflavin) can inhibit lipopolysaccharide (LPS)-induced NO production in vitro by RAW 264.7 cells and by thioglycolate-elicited peritoneal macrophages derived from four strains of mice (C57BL/6, BALB/c, LMP7/MECL-1^-/- and PPAR-α^-/- knockout mice). The present study was carried out in order to further explore the potential effects of diet supplementation with naturally-occurring inhibitors (δ-tocotrienol and quercetin) on LPS-stimulated production of NO, TNF-α, and other pro-inflammatory cytokines involved in the ageing process. Young (4-week-old) and senescent mice (42-week old) were fed control diet with or without quercetin (100 ppm), δ-tocotrienol (100 ppm), or dexamethasone (10 ppm; included as positive control for suppression of inflammation) for 4 weeks. At the end of feeding period, thioglycolate-elicited peritoneal macrophages were collected, stimulated with LPS, LPS plus interferon-β (IFN-β), or LPS plus interferon-γ (IFN-γ), and inflammatory responses assessed as measured by production of NO and TNF-α, mRNA reduction for TNF-α, and iNOS genes, and microarray analysis.

Results

Thioglycolate-elicited peritoneal macrophages prepared after four weeks of feeding, and then challenged with LPS (10 ng or 100 ng) resulted in increases of 55% and 73%, respectively in the production of NO of 46-week-old compared to 8-week-old mice fed control diet alone (respective control groups), without affecting the secretion of TNF-α among these two groups. However, macrophages obtained after feeding with quercetin, δ-tocotrienol, and dexamethasone significantly inhibited (30% to 60%; P < 0.02) the LPS-stimulated NO production, compared to respective control groups. There was a 2-fold increase in the production of NO, when LPS-stimulated macrophages of quercetin, δ-tocotrienol, or dexamethasone were also treated with IFN-β or IFN-γ compared to respective control groups. We also demonstrated that NO levels and iNOS mRNA expression levels were significantly higher in LPS-stimulated macrophages from senescent (0.69 vs 0.41; P < 0.05), compared to young mice. In contrast, age did not appear to impact levels of TNF-α protein or mRNA expression levels (0.38 vs 0.35) in LPS-stimulated macrophages. The histological analyses of livers of control groups showed lesions of peliosis and microvesicular steatosis, and treated groups showed Councilman body, and small or large lymphoplasmacytic clusters.

Conclusions

The present results demonstrated that quercetin and δ-tocotrienols inhibit the LPS-induced NO production in vivo. The microarray DNA analyses, followed by pathway analyses indicated that quercetin or δ-tocotrienol inhibit several LPS-induced expression of several ageing and pro-inflammatory genes (IL-1β, IL-1α, IL-6, TNF-α, IL-12, iNOS, VCAM1, ICAM1, COX2, IL-1RA, TRAF1 and CD40). The NF-κB pathway regulates the production of NO and inhibits the pro-inflammatory cytokines involved in normal and ageing process. These ex vivo results confirmed the earlier in vitro findings. The present findings of inhibition of NO production by quercetin and δ-tocotrienol may be of clinical significance treating several inflammatory diseases, including ageing process.

The immunoproteasomes regulate LPS-induced TRIF/TRAM signaling pathway in murine macrophages

We have proposed the novel concept that the macrophage ubiquitin-proteasome pathway functions as a key regulator of Lipopolysaccharide (LPS)-induced inflammation signaling. These findings suggest that proteasome-associated protease subunits X, Y, and Z are replaced by LMP subunits after LPS treatment of RAW 264.7 cells. The objective here was to determine the contribution of selective LMP proteasomal subunits to LPS-induced nitric oxide (NO) and TNF-α production in primary murine macrophages. Accordingly, thioglycollate-elicited macrophages from LMP7, LMP2, LMP10 (MECL-1), and LMP7/MECL-1 double knockout mice were stimulated in vitro with LPS, and were found to generate markedly reduced NO levels compared to wild-type (WT) mice, whereas TNF-α levels responses were essentially unaltered relative to wild-type responses. The recent studies suggest that the TRIF/TRAM pathway is defective in LMP knockouts which may explain why iNOS/NO are not robustly induced in LPS-treated macrophages from knockouts. Treating these macrophages with IFN-γ and LPS, however, reverses this defect, leading to robust NO induction. TNF-α is induced by LPS in the LMP knockout macrophages because IκB and IRAK are degraded normally via the MyD88 pathway. Collectively, these findings strongly support the concept that LMP7/MECL-1 proteasomes subunits actively function to regulate LPS-induced NO production by affecting the TRIF/TRAM pathway.

LPS-induced formation of immunoproteasomes: TNF-α and nitric oxide production are regulated by altered composition of proteasome-active sites

Stimulation of mouse macrophages with LPS leads to tumor necrosis factor (TNF-α) secretion and nitric oxide (NO) release at different times through independent signaling pathways. While the precise regulatory mechanisms responsible for these distinct phenotypic responses have not been fully delineated, results of our recent studies strongly implicate the cellular cytoplasmic ubiquitin-proteasome pathway as a key regulator of LPS-induced macrophage inflammatory responses. Our objective in this study was to define the relative contribution of specific proteasomal active-sites in induction of TNF-α and NO after LPS treatment of RAW 264.7 macrophages using selective inhibitors of these active sites. Our data provide evidence that LPS stimulation of mouse macrophages triggers a selective increase in the levels of gene and protein expression of the immunoproteasomes, resulting in a modulation of specific functional activities of the proteasome and a corresponding increase in NO production as compared to untreated controls. These findings suggest the LPS-dependent induction of immunoproteasome. In contrast, we also demonstrate that TNF-α expression is primarily dependent on both the chymotrypsin- and the trypsin-like activities of X, Y, Z subunits of the proteasome. Proteasome-associated post-acidic activity alone also contributes to LPS-induced expression of TNF-α. Taken together; our results indicate that LPS-induced TNF-α in macrophages is differentially regulated by each of the three proteasome activities. Since addition of proteasome inhibitors to mouse macrophages profoundly affects the degradation of proteins involved in signal transduction, we conclude that proteasome-specific degradation of several signaling proteins is likely involved in differential regulation of LPS-dependent secretion of proinflammatory mediators.

Suppression of nitric oxide induction and pro-inflammatory cytokines by novel proteasome inhibitors in various experimental models

Background

Inflammation has been implicated in a variety of diseases associated with ageing, including cancer, cardiovascular, and neurologic diseases. We have recently established that the proteasome is a pivotal regulator of inflammation, which modulates the induction of inflammatory mediators such as TNF-α, IL-1, IL-6, and nitric oxide (NO) in response to a variety of stimuli. The present study was undertaken to identify non-toxic proteasome inhibitors with the expectation that these compounds could potentially suppress the production of inflammatory mediators in ageing humans, thereby decreasing the risk of developing ageing related diseases. We evaluated the capacity of various proteasome inhibitors to suppress TNF-α, NO and gene suppression of TNF-α, and iNOS mRNA, by LPS-stimulated macrophages from several sources. Further, we evaluated the mechanisms by which these agents suppress secretion of TNF-α, and NO production. Over the course of these studies, we measured the effects of various proteasome inhibitors on the RAW 264.7 cells, and peritoneal macrophages from four different strains of mice (C57BL/6, BALB/c, proteasome double subunits knockout LMP7/MECL-1^-/-, and peroxisome proliferator-activated receptor-α,^-/- (PPAR-α,^-/-) knockout mice. We also directly measured the effect of these proteasome inhibitors on proteolytic activity of 20S rabbit muscle proteasomes.

Results

There was significant reduction of chymotrypsin-like activity of the 20S rabbit muscle proteasomes with dexamethasone (31%), mevinolin (19%), δ-tocotrienol (28%), riboflavin (34%), and quercetin (45%; P < 0.05). Moreover, quercetin, riboflavin, and δ-tocotrienol also inhibited chymotrypsin-like, trypsin-like and post-glutamase activities in RAW 264.7 whole cells. These compounds also inhibited LPS-stimulated NO production and TNF-α, secretion, blocked the degradation of P-IκB protein, and decreased activation of NF-κB, in RAW 264.7 cells. All proteasome inhibitors tested also significantly inhibited NO production (30% to 60% reduction) by LPS-induced thioglycolate-elicited peritoneal macrophages derived from all four strains of mice. All five compounds also suppressed LPS-induced TNF-α, secretion by macrophages from C57BL/6 and BALB/c mice. TNF-α, secretion, however, was not suppressed by any of the three proteasome inhibitors tested (δ-tocotrienol, riboflavin, and quercetin) with LPS-induced macrophages from LMP7/MECL-1^-/- and PPAR-α,^-/- knockout mice. Results of gene expression studies for TNF-α, and iNOS were generally consistent with results obtained for TNF-α, protein and NO production observed with four strains of mice.

Conclusions

Results of the current study demonstrate that δ-tocotrienol, riboflavin, and quercetin inhibit NO production by LPS-stimulated macrophages of all four strains of mice, and TNF-α, secretion only by LPS-stimulated macrophages of C57BL/6 and BALB/c mice. The mechanism for this inhibition appears to be decreased proteolytic degradation of P-IκB protein by the inhibited proteasome, resulting in decreased translocation of activated NF-κB to the nucleus, and depressed transcription of gene expression of TNF-α, and iNOS. Further, these naturally-occurring proteasome inhibitors tested appear to be relatively potent inhibitors of multiple proteasome subunits in inflammatory proteasomes. Consequently, these agents could potentially suppress the production of inflammatory mediators in ageing humans, thereby decreasing the risk of developing a variety of ageing related diseases.

Uraemic serum induces dysfunction of vascular endothelial cells: role of ubiquitin-proteasome pathway

The ubiquitin-proteasome pathway (UPP) has been indicated to contribute to dysfunction of endothelial cells (ECs). Nevertheless, the relationship between UPP and vascular complications of uraemia remains unknown. We aimed to determine whether the UPP is activated in vascular ECs when cultured with uraemic serum, and to examine the role of the UPP on dysfunction of ECs in uraemia. Rabbit aortic endothelial cells (RAECs) were cultured with normal serum or different concentrations of uraemic serum. The expression of the ubiquitin-activating enzyme (E1), an indicator of the UPP, was detected by real-time RT-PCR and Western blot; proteasome activity was determined by fluorescence spectrophotometry; and nuclear factor-κB (NF-κB) activity and expression, as well as tumour necrosis factor-α (TNF-α) expression, were also detected. We found that the expression of E1 and the activities of three kinds of proteasomes were increased significantly in RAECs after incubation with uraemic serum. Proliferation of RAECs was increased significantly by incubation with 3-15% uraemic serum but decreased markedly when incubated with uraemic serum above 15% (increased apoptosis). Incubation of RAECs with uraemic serum induced increased NF-B DNA-binding activity and nuclear translocation of NF-κB, decreased nitric oxide production and increased expression of TNF-α, which is the final effector of inflammatory activation of cells. All of these responses in RAECs were suppressed by the specific proteasome inhibitor, MG132. The inhibition of inflammatory responses by MG132 was further supported by a parallel experiment with pyrrolidine dithiocarbamate, a specific inhibitor of κNF-B. These findings suggest that the UPP was activated in RAECs by administration of uraemic serum, and played a pivotal role in the dysfunction of vascular ECs, such as inflammatory activation.

δ-Tocotrienol and quercetin reduce serum levels of nitric oxide and lipid parameters in female chickens

BACKGROUND

Chronic, low-grade inflammation provides a link between normal ageing and the pathogenesis of age-related diseases. A series of in vitro tests confirmed the strong anti-inflammatory activities of known inhibitors of NF-κB activation (δ-tocotrienol, quercetin, riboflavin, (-) Corey lactone, amiloride, and dexamethasone). δ-Tocotrienol also suppresses β-hydroxy-β-methylglutaryl coenzyme A (HMG-CoA) reductase activity (the rate-limiting step in de novo cholesterol synthesis), and concomitantly lowers serum total and LDL cholesterol levels. We evaluated these compounds in an avian model anticipating that a dietary additive combining δ-tocotrienol with quercetin, riboflavin, (-) Corey lactone, amiloride, or dexamethasone would yield greater reductions in serum levels of total cholesterol, LDL-cholesterol and inflammatory markers (tumor necrosis factor-α [TNF-α], and nitric oxide [NO]), than that attained with the individual compounds.

RESULTS

The present results showed that supplementation of control diets with all compounds tested except riboflavin, (-) Corey lactone, and dexamethasone produced small but significant reductions in body weight gains as compared to control. (-) Corey lactone and riboflavin did not significantly impact body weight gains. Dexamethasone significantly and markedly reduced weight gain (>75%) compared to control. The serum levels of TNF-α and NO were decreased 61% - 84% (P < 0.001), and 14% - 67%, respectively, in chickens fed diets supplemented with δ-tocotrienol, quercetin, riboflavin, (-) Corey lactone, amiloride, or dexamethasone as compared to controls. Significant decreases in the levels of serum total and LDL-cholesterol were attained with δ-tocotrienol, quercetin, riboflavin and (-) Corey lactone (13% - 57%; P < 0.05), whereas, these levels were 2-fold higher in dexamethasone treated chickens as compared to controls. Parallel responses on hepatic lipid infiltration were confirmed by histological analyses. Treatments combining δ-tocotrienol with the other compounds yielded values that were lower than individual values attained with either δ-tocotrienol or the second compound. Exceptions were the significantly lower total and LDL cholesterol and triglyceride values attained with the δ-tocotrienol/(-) Corey lactone treatment and the significantly lower triglyceride value attained with the δ-tocotrienol/riboflavin treatment. δ-Tocotrienol attenuated the lipid-elevating impact of dexamethasone and potentiated the triglyceride lowering impact of riboflavin. Microarray analyses of liver samples identified 62 genes whose expressions were either up-regulated or down-regulated by all compounds suggesting common impact on serum TNF-α and NO levels. The microarray analyses further identified 41 genes whose expression was differentially impacted by the compounds shown to lower serum lipid levels and dexamethasone, associated with markedly elevated serum lipids.

CONCLUSIONS

This is the first report describing the anti-inflammatory effects of δ-tocotrienol, quercetin, riboflavin, (-) Corey lactone, amiloride, and dexamethasone on serum TNF-δ and NO levels. Serum TNF-δ levels were decreased by >60% by each of the experimental compounds. Additionally, all the treatments except with dexamethasone, resulted in lower serum total cholesterol, LDL-cholesterol and triglyceride levels. The impact of above mentioned compounds on the factors evaluated herein was increased when combined with δ-tocotrienol.

The proteasome regulates bacterial CpG DNA-induced signaling pathways in murine macrophages

Our previous work has provided strong evidence that the proteasome is central to most of the genes induced in mouse macrophages in response to LPS stimulation. In the studies presented here, we evaluated the role of the macrophage proteasome in response to a second microbial product CpG DNA (unmethylated bacterial DNA). For these studies, we applied Affymetrix microarray analysis of RNA derived from murine macrophages stimulated with CpG DNA in the presence or absence of proteasome inhibitor, lactacystin. The results of these studies revealed that similar to LPS, most of those macrophage genes regulated by CpG DNA are also under the control of the proteasome at 4 h. In contrast to LPS stimulation, however, many of these genes were induced much later than 4 h, at 18 h, in response to CpG DNA. Lactacystin treatment of macrophages completely blocked the CpG DNA-induced gene expression of TNF-α and other genes involved in the production of inflammatory mediators. These data strongly support the conclusion that similar to LPS, the macrophage proteasome is a key regulator of CpG DNA-induced signaling pathways.

Tocotrienols inhibit lipopolysaccharide-induced pro-inflammatory cytokines in macrophages of female mice

Background

Inflammation has been implicated in cardiovascular disease, and the important role of proteasomes in the development of inflammation and other macrophage functions has been demonstrated. Tocotrienols are potent hypocholesterolemic agents that inhibit β-hydroxy-β-methylglutaryl coenzyme A reductase activity, which is degraded via the ubiquitin-proteasome pathway. Our objective was to evaluate the effect of tocotrienols in reducing inflammation. Lipopolysaccharide (LPS) was used as a prototype for inflammation in murine RAW 264.7 cells and BALB/c female mice.

Results

The present results clearly demonstrate that α-, γ-, or δ-tocotrienol treatments inhibit the chymotrypsin-like activity of 20 S rabbit muscle proteasomes (> 50%; P < 0.05). Chymotrypsin, trypsin, and post-glutamase activities were decreased > 40% (P < 0.05) with low concentrations (< 80 μM), and then increased gradually with concentrations of (80 - 640 μM) in RAW 264.7 whole cells. Tocotrienols showed 9 - 33% (P < 0.05) inhibitions in TNF-α secretion in LPS-stimulated RAW 264.7 cells. Results of experiments carried out in BALB/c mice demonstrated that serum levels of TNF-α after LPS treatment were also reduced (20 - 48%; P < 0.05) by tocotrienols with doses of 1 and 10 μg/kg, and a corresponding rise in serum levels of corticosterone (19 - 41%; P < 0.05) and adrenocorticotropic hormone (81 - 145%; P < 0.02) was observed at higher concentrations (40 μM). Maximal inhibition of LPS-induced TNF-α was obtained with δ-tocotrienol (10 μg/kg). Low concentrations of δ-Tocotrienols (< 20 μM) blocked LPS-induced gene expression of TNF-α, IL-1β, IL-6 and iNOS (> 40%), while higher concentrations (40 μM) increased gene expression of the latter in peritoneal macrophages (prepared from BALB/c mice) as compared to control group.

Conclusions

These results represent a novel approach by using natural products, such as tocotrienols as proteasome modulators, which may lead to the development of new dietary supplements of tocotrienols for cardiovascular diseases, as well as others that are based on inflammation.

Preventive effect of a proteasome inhibitor on the formation of accelerated atherosclerosis in rabbits with uremia

Inflammation plays a central role in the pathogenesis of atherosclerosis. This study investigated whether the proteasome inhibitor has the same preventive effect on the formation of accelerated atherosclerosis in rabbits with uremia compared with a NF-kappaB inhibitor. New Zealand white rabbits were subjected to five-sixths nephrectomy (chronic renal failure [CRF]) or to a sham operation. Rats in each group were randomly assigned into three subgroups (n = 24 in each group) and treated with repeated intramuscular injections of proteasome inhibitor MG132 or NF-kappaB inhibitor PDTC for a specified period. Compared with sham rabbits, CRF rabbits displayed typical atherosclerotic changes (endothelial cell damage, intimal thickens, and appearance of foam cells). CRF rabbits had significantly higher levels of proteasome activity, NF-kappaB mRNA, protein, and DNA binding activity as well as tumor necrosis factor-a and proliferative cell nuclear antigen protein expression in aortic wall cells. CRF rabbits also showed lower levels of IkappaBalpha. Compared with CRF rabbits, CRF rabbits treatment with proteasome inhibitor MG132 showed restoration of IkappaBalpha mRNA and protein expression and decreased NF-kappaB DNA binding activity and tumor necrosis factor-a expression. Treatment with either proteasome inhibitor MG132 or NF-kappaB inhibitor PDTC could reverse these pathologic changes in the aortic wall cells of CRF rabbits. A comparison between the inhibitory effects of the two treatments revealed no statistical difference. These results suggest that ubiquitin-proteasome activation play a pivotal role in the pathogenesis of uremia-accelerated atherosclerosis. The ubiquitin-proteasome signaling pathway in aortic cells may therefore be an important target for preventing uremia-accelerated atherosclerosis.

Identification of JAK-STAT pathways as important for the anti-inflammatory activity of a Hypericum perforatum fraction and bioactive constituents in RAW 264.7 mouse macrophages

Hypericum perforatum extracts have been used to treat diseases, including mild-to-moderate depression and inflammatory conditions. It is particularly important to identify which constituents present in the H. perforatum extracts are responsible for its anti-inflammatory activity since consumers are taking H. perforatum preparations to treat inflammation. We used a combination of four putative bioactive constituents, called the 4-component-system that interacted synergistically to explain the light-activated anti-inflammatory activity of an H. perforatum fraction in RAW 264.7 mouse macrophages. We also combined the constituents at concentrations detected in the fraction to identify key molecular targets. LPS was used to model an inflammatory response, and the 4-component-system and H. perforatum fraction were used as treatments that inhibited LPS-induced prostaglandin E(2) (PGE(2)) production in RAW 264.7 mouse macrophages in the studies of gene expression profiles. We used Affymetrix genechips, statistical analysis, and quantitative real-time PCR to identify key gene targets of the 4-component-system and the sub-fraction from an H. perforatum ethanol extract. The H. perforatum sub-fraction, with or without LPS stimulation, affected far more genes than the 4-component-system with and without LPS. Genes involved in Janus kinase, as well as a signal transducer and activator of transcription (JAK-STAT) and eicosanoid pathways were identified that could account for the reduction in PGE(2) observed with both treatments in LPS-stimulated macrophages. Ten genes may be particularly important targets for activity of the 4-component-system and the fraction with LPS stimulation and these genes were involved in inflammatory signaling pathways, namely the JAK-STAT and eicosanoid pathways.

Differential effects of lactacystin on cytokine production in activated Jurkat cells and murine splenocytes

Previous studies have demonstrated that the proteasome inhibitor, lactacystin, suppresses cytokine production and induction of other inflammatory mediators by LPS-stimulated macrophages. The purpose of the present studies was to determine the effect of lactacystin upon the function of activated human Jurkat T cells and murine splenocytes. Lactacystin treatment suppressed interleukin (IL)-2, interferon (IFN)gamma, and IL-13 production similarly in both activated Jurkat cells and primary splenocytes. Interestingly, lactacystin produced differential effects on IL-4 transcription in the two models. While lactacystin inhibited IL-4 mRNA transcription in primary splenocytes, it induced IL-4 mRNA in a concentration-dependent manner in Jurkat cells. The increase in IL-4 mRNA levels by lactacystin did not correlate with increases in T(H2)-specific transcription factors, avian musculoaponeurotic fibrosarcoma AS42 oncogene homolog (c-maf) or GATA binding protein 3 (GATA-3). In addition, the binding of both GATA-3 and t-bet to their respective response elements was essentially unchanged by lactacystin treatment in both splenocytes and Jurkat T cells, suggesting the induction of IL-4 is due to other mechanisms. Collectively, the current studies suggest proteasomal activity has differential effects on IL-4 transcription in activated Jurkat cells and primary splenocytes.

A combination of proteasome inhibitors and antibiotics prevents lethality in a septic shock model

Our recent studies with lactacystin, a prototype proteasome inhibitor, have suggested that the proteasome is a key regulator of LPS-induced signaling pathways contributing to the inflammatory process. Moreover, lactacystin protects animals from LPS-induced shock. Therefore, we sought to identify other less toxic compounds that would block the chymotrypsin-like activity of the proteasome or LPS-induced nitric oxide (NO). After screening over 100 natural compounds (based on chemistry and inhibition of LPS-induced biological activities), we now report for the first time that quercetin, like lactacystin (the prototype proteasome inhibitor), and mevinolin are also inhibitors of the chymotrypsin-like activity of the cellular proteasome within living cells. In addition, this study also suggests that mevinolin and quercetin both have relatively potent anti-inflammatory effects on LPS-treated macrophages in vitro. Interestingly, both of these compounds behave like lactacystin in that they block LPS-induced NO to a greater extent than TNF-alpha. The results of our experiments clearly suggest that mevinolin, in combination with the antibiotic imipenem, can provide protection against polymicrobial septic lethality induced by cecal-ligation and puncture in mice. Collectively, these studies strongly support the conclusion that therapeutic targeting of cellular proteasomes, in conjunction with standard antimicrobial therapy, may be of considerable survival benefit in the treatment of septic shock.

Targeting the ubiquitin proteasome pathway for the treatment of septic shock in patients

Endotoxic shock is a serious systemic inflammatory response to an external biological stressor. The responsiveness of NF-kappaB is built upon rapid protein modification and degradation involving the ubiquitin proteasome pathway. Using transgenic mice, we have obtained in vivo evidence that interference with this pathway can alleviate the symptoms of toxic shock. We posit that administration of proteasome inhibitors may enhance the survival of patients with septic shock.

Genome-wide transcriptional profiling of mononuclear phagocytes recruited to mouse lungs in response to alveolar challenge with the TLR2 agonist Pam3CSK4

Compared with the Toll-like receptor 4 (TLR4) ligand LPS restricted to gram-negative bacteria, few studies have addressed induction of lung inflammation and concomitant leukocyte recruitment in response to TLR2 ligands. This study is the first report showing that selective TLR2 stimulation by its ligand Pam(3)-Cys-Ser-Lys-Lys-Lys-Lys-OH (Pam(3)CSK(4)) within the alveolar compartment promoted lung inflammation in mice and induced the migration of circulatory immune cells including mononuclear phagocytes into the inflamed alveolar space. By using the transgenic CX(3)CR1(+/GFP) mouse strain for high-purity sorting of circulating and alveolar recruited mononuclear phagocytes together with SMART preamplification and whole genome oligonucleotide microarray techniques, we found that alveolar trafficking of mononuclear phagocytes was associated with profound changes of their gene expression profiles (approximately 900 differentially regulated genes postrecruitment). In particular, alveolar recruited mononuclear phagocytes showed upregulated transcripts of genes encoding cytokines/chemokines and pattern recognition receptor (PRR)-associated molecules. Notably, we observed a dynamic change of the genetic program of recruited mononuclear phagocytes obtained from bronchoalveolar lavage fluid at different time points (24 vs. 48 h) post-Pam(3)CSK(4) challenge. In early alveolar recruited mononuclear phagocytes, mRNA levels of both proinflammatory (e.g., TNF-alpha, CCL2, and IL-6) and central anti-inflammatory/ proresolution [e.g., IL-1-receptor antagonist (IL-1RN), CD200 receptor (CD200R), IL-1 receptor-associated kinase (IRAK-M), IL-10, and Bcl-2-associated X protein (Bax)] mediators were found to be highly upregulated simultaneously. In corresponding cells recruited until later time points, transcript levels of anti-inflammatory/proresolution molecules persisted at the same level, whereas mRNA levels of proinflammatory mediators were found to decline. Collectively, our in vivo study identifies genetic programs by which alveolar recruited mononuclear phagocytes may contribute to the development and termination of pneumonia caused by gram-positive bacteria.

Immune- and stress-related transcriptomic responses of Solea senegalensis stimulated with lipopolysaccharide and copper sulphate using heterologous cDNA microarrays

The sole, Solea senegalensis, is a common flatfish of Atlantic and Mediterranean waters with a high potential for aquaculture. However, its cultivation is hampered by high sensitivity to different stresses and several infectious diseases. Improving protection from pathogens and stressors is thus a key step in reaching a standardized production. Fish were exposed to lipopolysaccharide (LPS), a mimetic of bacterial infections, and copper sulphate (CuSO(4)), used in aquaculture to control algae and outbreaks of infectious diseases. We employed a European flounder cDNA microarray to determine the transcriptomic responses of Senegalese sole to these exposures. Microarray analyses showed that many genes were altered in expression following both LPS and copper treatments in comparison to vehicle controls. Gene ontology analysis highlighted copper-specific induction of genes related to cellular adhesion and cell signalling, LPS-specific induction of genes related to the immune response, and a common induction of genes related to unfolded protein binding, intracellular transport/secretion and proteasome. Additionally transcripts for glutathione-S-transferases were down-regulated by LPS, and those for digestive enzymes were down-regulated by both treatments. We selected nine changing genes for absolute quantification of transcript copy numbers by real-time RT-PCR to validate microarray differential expression and to assess inter-individual variability in individual fishes. The quantitative RT-PCR data correlated highly with the microarray results. Overall, data reported provide novel insights into the molecular pathways that could mediate the immune and heavy metal stress responses in Senegalese sole and thus might have biotechnological applications in the culture of this important fish species.

Inductive and suppressive networks regulate TLR9-dependent gene expression in vivo

Bacterial DNA expressing unmethylated CpG motifs binds to TLR9, thereby stimulating a broadly protective, innate immune response. Although CpG-mediated signal transduction has been studied, the scope of TLR9-dependent gene expression is incompletely understood. To resolve these issues, mice were treated with immunostimulatory CpG oligonucleotides (ODN) and splenic mRNA levels monitored from 30 min through 3 days by microarray. Through the unique application of bioinformatic analysis to these experimental data, this study is the first to describe the complex regulatory networks responsible for TLR9-mediated gene expression. Current results are the first to establish that CpG-induced stimulation of the innate immune system proceeds in multiple waves over time, and gene up-regulation is mediated by a small number of temporally activated "major inducers" and "minor inducers". An additional study of TNF knockout mice supports the conclusion that the regulatory networks identified by our bioinformatic analysis accurately identified CpG ODN-driven gene-gene interactions in vivo. Equally important, this work identifies the counter-regulatory mechanisms embedded within the signaling cascade that suppresses the proinflammatory response triggered in vivo by CpG DNA stimulation. Identifying these network interactions provides novel and global insights into the regulation of TLR9-mediated gene activation, improves our understanding of TLR-mediated host defense, and facilitates the development of interventions designed to optimize the nature and duration of the ensuing response.

Lipid A-mediated tolerance and cancer therapy

The term "tolerance" from an immunological perspective, broadly encompasses a number of phenomena, but generally refers to a diminished responsiveness to LPS and/or other microbial products. With the discovery that many of the immunological, physiological and/or pathophysiological effects of LPS can be attributed to the lipid A moiety of the LPS molecule, a number of different lipid A analogs were synthesized with the goal of developing a drug that could be used clinically to treat cancer. In many instances, the development of tolerance to the lipid A congeners confounded the utility of these analogs as cancer therapeutics. In certain circumstances, however, the development of tolerance in patients has been utilized therapeutically to protect immunosuppressed patients from sepsis. Although numerous studies have been designed to investigate the development of tolerance, the underlying molecular mechanism remains unclear. This may be due, in part, to differences in the experimental models used, the sources and types of microbes and microbial products studied, kinetics of responses, and/or other experimental conditions. Nonetheless, a number of different signaling pathways have been identified as potentially modulating and/or triggering the development of tolerance. Though complex and incompletely understood, the capacity of tolerance to impact lipid A-based therapeutics, either positively or negatively, is inarguable, thus underscoring the necessity for further investigation toward elucidating the mechanisms contributing to the development of tolerance to lipid A and its analogs.

Stromal cells in bone marrow play important roles in pro-inflammatory cytokine secretion causing fever following bortezomib administration in patients with multiple myeloma

Bortezomib blocks the activation of nuclear factor-kappaB-mediated pro-inflammatory cytokines, however, systemic inflammatory symptoms following bortezomib administration have been reported, although their mechanisms remain elusive. Serum samples were obtained from five patients, who participated in a phase I/II study of Japanese patients with relapsed or refractory multiple myeloma (MM), and developed cyclic fever following bortezomib administration, to measure cytokine levels. Significant correlations between interleukin (IL)-6 or interferon (IFN)-gamma and the body temperature were observed in two patients each. Furthermore, we found that IL-6 elevation was not observed after the addition of bortezomib to any examined MM cells alone, but was noted in a case of bone marrow stromal cells (BMSCs) of macrophage origin alone or co-cultured with MM cells. Similarly, a marked increase in IFN-gamma levels was induced by adding bortezomib to BMSCs of fibroblast origin. Although this investigation was a preliminary study with a small number of patients, our results suggested that pro-inflammatory cytokines causing bortezomib-associated fever were secreted from BMSCs rather than MM cells.

Role of proteasomes in disease

A functional ubiquitin proteasome system is essential for all eukaryotic cells and therefore any alteration to its components has potential pathological consequences. Though the exact underlying mechanism is unclear, an age-related decrease in proteasome activity weakens cellular capacity to remove oxidatively modified proteins and favours the development of neurodegenerative and cardiac diseases. Up-regulation of proteasome activity is characteristic of muscle wasting conditions including sepsis, cachexia and uraemia, but may not be rate limiting. Meanwhile, enhanced presence of immunoproteasomes in aging brain and muscle tissue could reflect a persistent inflammatory defence and anti-stress mechanism, whereas in cancer cells, their down-regulation reflects a means by which to escape immune surveillance. Hence, induction of apoptosis by synthetic proteasome inhibitors is a potential treatment strategy for cancer, whereas for other diseases such as neurodegeneration, the use of proteasome-activating or -modulating compounds could be more effective. Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com).

The value of sepsis definitions in daily ICU-practice

Sepsis is a major disease entity with important clinical and economic implications. Sepsis is the hosts' reaction to infection and is characterized by a systemic inflammatory response. Because of difficulties in defining sepsis, the SIRS was introduced trying to summarize the inflammatory response in a limited set of elementary characteristics (fever or hypothermia, leucocytosis or leucopenia, tachycardia, hyperventilation). In daily practice it is essential to identify septic patients as soon as possible because early recognition results in better survival rates. However, in order to allow early detection, a more stringent description of "the septic profile" is needed. From the start, even after revision of the primary sepsis description, these definitions have caused much controversy and debate because they lack sensitivity and specificity. Conclusively, almost all patients admitted to the intensive care unit meet or develop the systemic inflammatory response syndrome. Therefore, it is difficult to distinguish patients with true sepsis from those with severe inflammation due to non-infectious causes. This review highlights the current sepsis definitions, and discusses their strengths as well as their shortcomings for daily intensive care unit practice.