Involvement of ERK-1/2 in IL-21-induced cytokine production in leukemia cells and human monocytes

Cytokines play an important role in the immune system, and abnormalities in their production have been found in many human diseases. Interleukin-21 (IL-21), a type I cytokine produced by activated T cells, has diverse effects on the immune system, but its ability to induce production of other cytokines is not well delineated. Furthermore, the signaling pathway underlying its action is poorly understood. Here, we have evaluated IL-21-induced cytokine production in human monocytes and U937 leukemia cells. We found that IL-21 induces upregulation of a variety of cytokines from multiple cytokine families. We also found that IL-21 triggers rapid activation of ERK1/2. Neutralizing antibody to the IL-21R prevented both IL-21-induced cytokine production and IL-21-induced activation of ERK1/2. Inhibition of ERK1/2 activity by the ERK-selective inhibitor U0126 reverses the ability of IL-21 to upregulate cytokine production, suggesting that IL-21-induced cytokine production is dependent on ERK1/2 activation.     

Cytokine Regulation of Neuronal Survival

Interleukin-1 is a cytokine involved in the immune response to infection and inflammation as well as a growth promotor for several cell types. Interleukin-1-like immunoreactive material has been found in the nervous system. We now show that antisera, which blocked the T-cell proliferative effects of interleukin-1 alpha, decreased neuronal cell counts (to 40% of control) in dissociated spinal cord cultures derived from fetal mice. This neuronal loss was prevented by addition of interleukin-1 alpha, and to a lesser extent by interleukin-1 beta. Exogenous interleukin-1 alpha increased the survival of neurons when added to cultures in which the electrical activity was blocked with tetrodotoxin, whereas no such cytokine-related increase in neuronal survival was observed in electrically active cultures. The antiserum-induced death could also be prevented by cotreatment of the cultures with 0.1 nM vasoactive intestinal peptide, a substance that induces the secretion of neuronal trophic factors from nonneuronal spinal cord cells and thereby increases neuronal survival in electrically inactive cultures. These studies indicate that the cytokine interleukin-1, or an immunologically cross-reactive protein, can increase neuronal survival.     

Use of the anti-inflammatory cytokine interleukin-11 to reverse HIV-1gp120 repression of a natural killer cell line

Enhancing natural killer (NK) cell activation has been associated with protection from human immunodeficiency virus-1 (HIV-1) infections and slowed onset of immunodeficiency. However, soluble HIV-1 envelope protein, gp120, has been shown to impair NK cell cytokine secretion and cell-mediated cytotoxicity. Here we show that gp120 suppressed IFN-γ production and cytotoxic function of a human NK cell line NK-92MI. We furthermore demonstrated that an anti-inflammatory cytokine interleukin-11 can restore effector functions to repressed NK-92MI cells. These studies support the notion that IL-11 administration may reduce HIV-1-mediated immune activation and exhaustion while achieving elimination of virally-infected cells through restored NK cell function.     

Cystatin SA, a cysteine proteinase inhibitor, induces interferon-gamma expression in CD4-positive T cells

Recently, it has been demonstrated that family 2 cystatins upregulate interleukin-6 production by human gingival fibroblasts. In the present study, we investigated the effects of cystatin SA on cytokine production by helper T cells. Human CD4-positive T cells were cultured with phytohemagglutinin in the presence or absence of 0.1 microM recombinant cystatin SA1 or SA2. When the amounts of interleukin-4 (IL-4) and interferon-gamma (IFNgamma) were analyzed in an ELISA system after stimulation with either cystatin, no significantly increased levels of IL-4 were detected. However, the amounts of IFNgamma were significantly increased after stimulation with the cystatins. Our results suggest that salivary family 2 cystatins are involved in immune responses through the cytokine network.     

NLRP3炎性小体研究新进展

NLRP3炎性小体是一种分子量约为700Kda的大分子多蛋白复合体,能被多种病原相关的分子模式或损伤相关的分子模式活化,对固有免疫系统免疫功能的发挥具有极其重要的作用。但如果其被过度激活则可通过活化的半胱天冬酶-1持续地将pro-IL-1β和pro-IL-18剪切为成熟的IL-1β和IL-18,进而激活下游信号转导通路,产生大量的炎性介质,引起机体发生严重的炎症反应,最终促进多种炎症性疾病的发生与发展,如Muckle—wells综合征、2型糖尿病、非酒精性脂肪肝、动脉粥样硬化、炎症性肠病和阿尔兹海默病等。因此,对NLRP3炎性小体进行深入的研究不仅有助于阐释固有免疫系统如何有效地发挥其免疫功能,而且作为系列炎症反应的核心,NLRP3炎性小体：还可能成为多种炎症性疾病防治的新靶点。我们就NLRP3炎性小体的结构与功能,激活与调控,分布与疾病的近期研究作一综：违。     

Leptin as an immunomodulator

Leptin is an adipocyte-derived hormone/cytokine that links nutritional status with neuroendocrine and immune functions. In humans, leptin influences energy homeostasis and regulates neuroendocrine function primarily in states of energy deficiency. Initially described as an antiobesity hormone, leptin has subsequently been shown also to influence basal metabolism, hematopoiesis, thermogenesis, reproduction, and angiogenesis. As a cytokine, leptin can affect thymic homeostasis and the secretion of acute-phase reactants such as interleukin-1 (IL-1) and tumor-necrosis factor-alpha (TNF-α). Leptin links nutritional status and proinflammatory T helper 1 (Th1) immune responses and the decrease in leptin plasma concentration during food deprivation leads to impaired immune function. Similar to other pro-inflammatory cytokines, leptin promotes Th1-cell differentiation and can modulate the onset and progression of autoimmune responses in several animal models of disease. Here, we review the advances and controversy for a role of leptin in the pathophysiology of immune responses and discuss novel possible therapeutic implications for leptin modulators.     

Anti-human cytomegalovirus activity of cytokines produced by CD4+ T-cell clones specifically activated by IE1 peptides in vitro.

The control of latent cytomegalovirus (CMV) infections by the immune system is poorly understood. We have previously shown that CD4+ T cells specific for the human CMV major regulatory protein IE1 are frequent in latently infected healthy blood donors. In order to learn about the possible role of these cells, we have developed IE1-specific CD4+ T-cell clones and, in this study, analyzed their epitope specificity and function in vitro. We measured their cytokine production when stimulated with specific IE1 peptides or whole recombinant IE1 protein. Their cytokine profiles, as deduced from gamma interferon (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), and interleukin-4 (IL-4) and IL-6 production, were of the Th0- and Th1-like phenotypes. Supernatants from IE1-specific clones producing IFN-gamma and TNF-alpha were shown to inhibit CMV replication in U373 MG cells. This effect was due, as found by using cytokine-specific neutralizing antibodies, mostly to IFN-gamma, which was secreted at higher levels than TNF-alpha. To better assess the anti-CMV activity of cytokines, recombinant IFN-gamma and TNF-alpha were used and shown to have a synergistic effect on the inhibition of CMV replication and protein expression. Thus, IE1-specific CD4+ T cells display in vitro anti-CMV activity through cytokine secretion and may play a role in the control of in vivo latent infections.     

A Coding IRAK2 Protein Variant Compromises Toll-like receptor (TLR) Signaling and Is Associated with Colorectal Cancer Survival

Within innate immune signaling pathways, interleukin-1 receptor-associated kinases (IRAKs) fulfill key roles downstream of multiple Toll-like receptors and the interleukin-1 receptor. Although human IRAK4 deficiency was shown to lead to severe immunodeficiency in response to pyogenic bacterial infection during childhood, little is known about the role of human IRAK2. We here identified a non-synonymous IRAK2 variant, rs35060588 (coding R214G), as hypofunctional in terms of NF-κB signaling and Toll-like receptor-mediated cytokine induction. This was due to reduced ubiquitination of TRAF6, a key step in signal transduction. IRAK2 rs35060588 occurs in 3–9% of individuals in different ethnic groups, and our studies suggested a genetic association of rs35060588 with colorectal cancer survival. This for the first time implicates human IRAK2 in a human disease and highlights the R214G IRAK2 variant as a potential novel and broadly applicable biomarker for disease or as a therapeutic intervention point.     

Evolution of interleukin-1beta

All jawed vertebrates possess a complex immune system, which is capable of anticipatory and innate immune responses. Jawless vertebrates posses an equally complex immune system but with no evidence of an anticipatory immune response. From these findings it has been speculated that the initiation and regulation of the immune system within vertebrates will be equally complex, although very little has been done to look at the evolution of cytokine genes, despite well-known biological activities within vertebrates. In recent years, cytokines, which have been well characterised within mammals, have begun to be cloned and sequenced within non-mammalian vertebrates, with the number of cytokine sequences available from primitive vertebrates growing rapidly. The identification of cytokines, which are mammalian homologues, will give a better insight into where immune system communicators arose and may also reveal molecules, which are unique to certain organisms. Work has focussed on interleukin-1 (IL-1), a major mediator of inflammation which initiates and/or increases a wide variety of non-structural, function associated genes that are characteristically expressed during inflammation. Other than mammalian IL-1β sequences there are now full cDNA sequences and genomic organisations available from bird, amphibian, bony fish and cartilaginous fish, with many of these genes having been obtained using an homology cloning approach. This review considers how the IL-1β gene has changed through vertebrate evolution and whether its role and regulation are conserved within selected non-mammalian vertebrates.     

Therapeutic efficacy of IL-17 neutralization in murine experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is widely regarded as an animal model of the human disease multiple sclerosis. A multitude of studies has investigated the neuroantigen-specific T-cell mediated cytokine pattern present in animals with EAE. In particular, the role of the so-called Th1- and Th2-cytokines has been addressed. In a recent study, it has been demonstrated that IL-23 rather than IL-12 is critical for modulating the character of the developing immune response towards a proinflammatory response and leading to EAE. IL-17 is a crucial effector cytokine, whose production is specifically triggered by IL-23, and it has been shown to be an essential inflammatory mediator in other autoimmune diseases and inflammatory conditions. This led us to investigate the role of IL-17 in EAE. Strong antigen-specific production of IL-17 was demonstrated both in peripheral immune organs and in the CNS in acute and chronic EAE, as demonstrated by ELISPOT and RT-PCR analysis. Therapeutic neutralization of IL-17 with IL-17-receptor-Fc-protein in acute EAE ameliorated clinical symptoms. Neutralization of IL-17 with a monoclonal antibody also ameliorated the disease course. We conclude that IL-17 is crucially involved in the cytokine network as an effector cytokine in EAE.     

Single-step purification and structural characterization of human interleukin-6 produced in Escherichia coli from a T7 RNA polymerase expression vector

Human interleukin-6 or B-cell stimulatory factor-2 is a cytokine involved in acute phase and immune response. Cloning of cDNA for human interleukin-6 in the pT7.7 expression plasmid under the control of a bacteriophage T7 RNA polymerase promoter system allows rapid production of the cytokine in Escherichia coli. Upon cell induction with isopropyl thiogalactopyranoside, recombinant human interleukin-6 is overexpressed and forms insoluble inclusion bodies. Solubilization of the protein with 6 M guanidine hydrochloride and refolding in the presence of a reduction/oxidation system results in a quantitative recovery of recombinant human interleukin-6. This material is already 70% pure and can be further purified to homogeneity with a single passage over a weak anionic-exchange column. Extended structural characterization of the purified protein by electrospray mass spectrometry, automated Edman degradation and peptide mapping by high-pressure liquid chromatography/fast-atom-bombardment mass spectrometry demonstrates that recombinant human interleukin-6 is identical to the natural protein both in amino acid sequence and S-S bridge content. However, it contains a minor component accounting for about 20% of the entire translated protein which exhibits a Met-Ala dipeptide extension at the N-terminus. Purified recombinant human interleukin-6 is biologically active because it is able to induce at least 70-fold the human C-reactive promoter transfected in human hepatoma Hep 3B cells and is stable for several months in 10% glycerol at 4 degrees C. The expression system described in the present work has the main advantage of producing a high yield of recombinant human interleukin-6 (about 25 mg/l) combined with a very simple purification scheme.     

Dual biological effects of the cytokines interleukin-10 and interferon-γ

It is generally thought that each cytokine exerts either immune stimulatory (inflammatory) or immune inhibitory (antiinflammatory or regulatory) biological activities. However, multiple cytokines can enact both inhibitory and stimulatory effects on the immune system. Two of these cytokines are interleukin (IL)-10 and interferon-gamma (IFNγ). IL-10 has demonstrated antitumor immunity even though it has been known for years as an immunoregulatory protein. Generally perceived as an immune stimulatory cytokine, IFNγ can also induce inhibitory molecule expression including B7-H1 (PD-L1), indoleamine 2,3-dioxygenase (IDO), and arginase on multiple cell populations (dendritic cells, tumor cells, and vascular endothelial cells). In this review, we will summarize current knowledge of the dual roles of both of these cytokines and stress the previously underappreciated stimulatory role of IL-10 and inhibitory role of IFNγ in the context of malignancy. Our progressive understanding of the dual effects of these cytokines is important for dissecting cytokine-associated pathology and provides new avenues for developing effective immune therapy against human diseases, including cancer.     

Cytokine Gene Expression Within the Central Nervous System

1. The identification of cytokine genes expressed in the central nervous system is critical to understanding the immune network in various diseases of brain, such as infection, degeneration, and malignancy.2. Expression of cytokine genes in human astrocytoma cell lines and in fresh brain specimens was studied by the reverse-transcribed/polymerase chain reaction method.3. The correlation between clinical malignancy and cytokine gene expression within malignant glioma was examined, especially regarding the relevancy of inhibitory cytokines, such as transforming growth factor- and interleukin-10.     

Anti-Inflammatory Effects of IL-27 in Zymosan-Induced Peritonitis: Inhibition of Neutrophil Recruitment Partially Explained by Impaired Mobilization from Bone Marrow and Reduced Chemokine Levels

Rapid activation of the innate immune system is critical for an efficient host response to invading pathogens. However, the inflammatory reaction has to be strictly controlled to minimize harmful immunopathology. A number of mediators including the cytokine interleukin-27 (IL-27) appear to be responsible for limitation and resolution of inflammation. Despite increasing knowledge of its suppressive effects on T cells, the influence on neutrophils and macrophages is poorly understood. To determine the role of IL-27 in innate immune responses we analysed the effect of IL-27 in a T cell independent model of zymosan-induced peritonitis. Early administration of recombinant IL-27 strongly reduced the number of neutrophils recruited to the peritoneal cavity after zymosan application as well as the neutrophil frequency in the blood. Simultaneously, IL-27 reduced the release of neutrophils from the bone marrow upon inflammation. Although cytokine levels were not affected by IL-27 treatment, the levels of the chemokines KC, MCP-1 and MIP-1α in the peritoneal fluid were strongly decreased. These findings demonstrate that IL-27 is able to control mobilisation and recruitment of neutrophils into the peritoneal cavity and identify a novel mechanism to limit inflammation caused by innate immune cells.     

Homologues of human macrophage migration inhibitory factor from a parasitic nematode. Gene cloning,protein activity,and crystal structure

Cytokines are the molecular messengers of the vertebrate immune system, coordinating the local and systemic immune responses to infective organisms. We report here functional and structural data on cytokine-like proteins from a eukaryotic pathogen. Two homologues of the human cytokine macrophage migration inhibitory factor (MIF) have been isolated from the parasitic nematode Brugia malayi. Both molecules (Bm-MIF-1 and Bm-MIF-2) show parallel functions to human MIF. They are chemotactic for human monocytes and activate them to produce IL-8, TNF-alpha, and endogenous MIF. The human and nematode MIF homologues share a tautomerase enzyme activity, which is in each case abolished by the mutation of the N-terminal proline residue. The crystal structure of Bm-MIF-2 at 1.8-A resolution has been determined, revealing a trimeric assembly with an inner pore created by beta-stranded sheets from each subunit. Both biological activity and crystal structure reveal remarkable conservation between a human cytokine and its parasite counterpart despite the considerable phylogenetic divide among these organisms. The strength of the similarity implies that MIF-mediated pathways play an important role in nematode immune evasion strategies.     

The peptidyl-prolyl isomerase Pin1 regulates granulocyte-macrophage colony-stimulating factor mRNA stability in T lymphocytes

Cytokine production is associated with both the normal and pathologic inflammatory response to injury. Previous studies have shown that the immunosuppressants cyclosporin A or FK506, which interact with the peptidyl-propyl isomerases cyclophilin A and FK506-binding protein (FKBP12), respectively, block cytokine expression. A third member of the peptidyl-propyl isomerase family, Pin1 is expressed by immune and other cells. Pin1 has been implicated in cell cycle progression, is overexpressed in human tumors, and may rescue neurons from tau-associated degeneration. However, the role of Pin1 in the immune system remains largely unknown. In this study, we analyze the role of Pin1 in GM-CSF expression by human PBMC and CD4+ lymphocytes. We show that Pin1 isomerase activity is necessary for activation-dependent, GM-CSF mRNA stabilization, accumulation, and protein secretion, but not non-AU-rich elements containing cytokine mRNAs, including TGF-beta and IL-4. Mechanistically, Pin1 mediated the association of the AU-rich element-binding protein, AUF1, with GM-CSF mRNA, which determined the rate of decay by the exosome.     

Natural antibodies to IL-2

Natural antibodies to human interleukin-2 are present in sera of patients infected with human immunodeficiency virus and also, at a lower titre, in sera of healthy individuals. These antibodies could be purified by affinity-chromatography. Purified human anti-hIL-2 antibodies can interfere with lymphocyte proliferation both in the lymphokine activated killer cell assay and in the mixed lymphocyte culture. The neutralizing activity observedin vitro suggests that these antibodies play a role in the elaborate cytokine network by which the immune system regulates its response.     

Spontaneous production of interleukin-1-like cytokine from a mouse osteoblastic cell line (MC3T3-E1)

We have investigated the role of interleukin-1 in the regulatory mechanisms of a bone remodeling system. Osteoblastic cell line (MC3T3-E1) established from newborn mouse calvaria spontaneously produced interleukin-1-like cytokine. Although the interleukin-1-like activity was not observed in culture supernatants of the cells during their exponential phase of growth, a most remarkable interleukin-1-like activity was detected in the supernatants of cells cultured in serum-free alpha-MEM on day 5 after the cells had formed a confluent monolayer. Gel filtration analysis indicated that the interleukin-1-like cytokine exhibits some heterogeneity in size.     

The weight of leptin in immunity

Leptin is an adipocyte-derived hormone/cytokine that links nutritional status with neuroendocrine and immune functions. As a hormone, leptin regulates food intake and basal metabolism, and is sexually dimorphic - that is, its serum concentration is higher in females than in males with a similar body fat mass. As a cytokine, leptin can affect thymic homeostasis and the secretion of acute-phase reactants such as interleukin-1 and tumour-necrosis factor. Similar to other pro-inflammatory cytokines, leptin promotes T helper 1 (TH1)-cell differentiation and can modulate the onset and progression of autoimmune responses in several animal models of disease. Here, we review the advances and controversy for a role of leptin in the pathophysiology of immune responses.