Interleukin-1β Inhibits Glutamate Release in Hippocampus of Young,But Not Aged,Rats

The proinflammatory cytokine, interleukin-1, is synthesized in neuronal and glial cells and is released in response to stress/injury. IL-1 exerts profound effects on the central nervous system, which include an inhibitory effect on synaptic activity in hippocampus, a brain area expressing a high density of IL-1 receptors. We report that IL-1β has an inhibitory effect on KCl-stimulated release of glutamate and KCl-stimulated [⁴⁵Ca] influx in synaptosomes prepared from hippocampus of 4-month-old rats. These effects were inhibited by the endogenous receptor antagonist, IL-1ra, and by the phospholipase A₂ (PLA₂) inhibitor, quinacrine, suggesting that IL-1 receptor activation is coupled to PLA₂. An inhibitory effect of IL-1β on protein kinase C activity was also observed. KCl-induced calcium-dependent release and calcium influx, and protein kinase C activity were significantly decreased in hippocampal synaptosomes prepared from 22-month-old compared to 4-month-old animals. In contrast to the inhibitory effect of IL-1β in synaptosomes prepared from young adult animals, no effect was observed on release, calcium influx, or protein kinase C activity in synaptosomes prepared from aged animals. We report that there is an age-related increase in expression of IL-1β in hippocampus and propose that this change may underlie the attenuated responses to IL-1β in hippocampus of aged animals.     

The Role of Neutral Sphingomyelinase in Interleukin-1β Signal Transduction in Mouse Cerebral Cortex Cells

The cytokine interleukin-1 (IL-1) is an important mediator of neuroimmune interactions, though it has not been established precisely how the IL-1 signal is transmitted in nerve cells. This study demonstrates the involvement of the sphingomyelin cascade in IL-1 signal transduction in the P2 membrane fraction of the mouse cerebral cortex. The key role of the membrane enzyme neutral sphingomyelinase in initiating the sphingomyelin signal transduction pathway for this cytokine is supported. The stimulating activity of IL-1 on sphingomyelinase activity in the P2 fraction of the cerebral cortex was found to be dose-dependent. Studies using this membrane fraction from mice lacking the IL-1 type I receptor due to genomic mutations, along with studies using an IL-1 receptor antagonist, yielded data showing that IL-1 binding with the type I receptor is a necessary event for activation of neutral sphingomyelinase. The results obtained here lead to the conclusion that the action of IL-1 in the CNS is mediated by the IL-1 type I receptor and activation of neutral sphingomyelinase as the initiating enzyme of the sphingomyelin cascade.     

Interleukin-1β in human colostrum

The two forms of interleukin-1, IL-1α and IL-1β respectively, and tumour necrosis factor (TNF) are polypeptides sharing different biological activities which are often associated with host defence mechanisms. Because of the well-recognized benefits of breast feeding for newborns, colostrum from 9 healthy lactating women was analysed for the presence of these 3 cytokines. Specific radioimmunoassay revealed that colostrum contains a significant amount of IL-1β (mean ± SEM values of 1,130 ± 259 pg/ml). The concentrations of IL-1α and TNF were negligible.Colostral leukocytes are able to produce IL-1 since high activity was found after stimulation with Staphylococcus epidermidis. In addition, these cells produced IL-1 spontaneously in vitro, in contrast to resting maternal blood monocytes. As IL-1 increases resistance to infection, the presence of this cytokine represent a beneficial aspect of breast feeding.     

Tubular Overexpression of Transforming Growth Factor-β1 Induces Autophagy and Fibrosis but Not Mesenchymal Transition of Renal Epithelial Cells

We recently showed in a tetracycline-controlled transgenic mouse model that overexpression of transforming growth factor (TGF)-β1 in renal tubules induces widespread peritubular fibrosis and focal degeneration of nephrons. In the present study we have analyzed the mechanisms underlying these phenomena. The initial response to tubular cell-derived TGF-β1 consisted of a robust proliferation of peritubular cells and deposition of collagen. On sustained expression, nephrons degenerated in a focal pattern. This process started with tubular dedifferentiation and proceeded to total decomposition of tubular cells by autophagy. The final outcome was empty collapsed remnants of tubular basement membrane embedded into a dense collagenous fibrous tissue. The corresponding glomeruli survived as atubular remnants. Thus, TGF-β1 driven autophagy may represent a novel mechanism of tubular decomposition. The fibrosis seen in between intact tubules and in areas of tubular decomposition resulted from myofibroblasts that were derived from local fibroblasts. No evidence was found for a transition of tubular cells into myofibroblasts. Neither tracing of injured tubules in electron micrographs nor genetic tagging of tubular epithelial cells revealed cells transgressing the tubular basement membrane. In conclusion, overexpression of TGF-β1 in renal tubules in vivo induces interstitial proliferation, tubular autophagy, and fibrosis, but not epithelial-to-mesenchymal transition.The release of transforming growth factor (TGF)-β1 plays a central role in fibrosis following tissue injury. On the one hand, the formation of fibrous scars contributes to healing in various tissues. On the other hand, fibrosis is considered a driving force in the progression of chronic renal failure. Therefore, much effort has been made in unraveling the cellular and molecular processes, which underlie renal interstitial fibrosis. TGF-β1 is thought to trigger several mechanisms that lead to fibrosis, among them activation of resident fibroblasts and stimulation of tubular epithelial cells to transform into mesenchymal cells, ie, into fibroblasts and myofibroblasts.^1,2,3,4,5 This latter process is called epithelial-to-mesenchymal transition (EMT)^6,7; its impact on fibrosis development in chronic renal disease is a matter of controversy.We recently reported a tetracycline-inducible transgenic mouse model, in which conditional overexpression of TGF-β1 in renal tubules induced widespread peritubular fibrosis and focal nephron degeneration.⁸ Thus, this model provides a unique tool to titrate parenchymal injury and fibrosis induced by TGF-β1. We used this model to study in detail the mechanism of tubular decomposition and the development of fibrosis in response to TGF-β1 including the role of EMT in these processes.The damage induced by TGF-β1 overexpression was analyzed by structural and immunocytochemical techniques. In particular, we wanted to elucidate the sequence how tubules undergo decomposition and tubular cells participate in fibrosis development. An epithelial cell is a polarized cell with clearly separated apical and basolateral surfaces. A fibroblast/myofibroblast is an unpolarized cell generally with many cell processes. Thus, if an epithelial cell transforms into a fibroblastoid cell, we would expect to encounter intermediate stages with an intermediate transitional morphology. Moreover, renal tubular epithelial cells are strictly enclosed into a continuous cylinder of the tubular basement membrane (TBM). Thus, for a tubular cell to become a fibroblast/myofibroblast, it is not only necessary that it changes its morphology and its specific protein composition, but it has also to change its location. It has to leave the tubular compartment, to migrate through the TBM, and to take residency in the peritubular interstitium. Furthermore, it has to undergo a genetic reprogramming to (re)differentiate into a specialized different cell type. These changes in shape and in location should be detectable in usual histopathological specimens by high-resolution light and electron microscopy. In addition, we used fate-tracing techniques to identify the origin of cells involved in peritubular proliferation.     

Critical Role for Interleukin-1β (IL-1β) during Chlamydia muridarum Genital Infection and Bacterial Replication-Independent Secretion of IL-1β in Mouse Macrophages

Recent findings have implicated interleukin-1β (IL-1β) as an important mediator of the inflammatory response in the female genital tract during chlamydial infection. But how IL-1β is produced and its specific role in infection and pathology are unclear. Therefore, our goal was to determine the functional consequences and cellular sources of IL-1β expression during a chlamydial genital infection. In the present study, IL-1β^−/− mice exhibited delayed chlamydial clearance and decreased frequency of hydrosalpinx compared to wild-type (WT) mice, implying an important role for IL-1β both in the clearance of infection and in the mediation of oviduct pathology. At the peak of IL-1β secretion in WT mice, the major producers of IL-1β in vivo are F4/80⁺ macrophages and GR-1⁺ neutrophils, but not CD45⁻ epithelial cells. Although elicited mouse macrophages infected with Chlamydia muridarum in vitro secrete minimal IL-1β, in vitro prestimulation of macrophages by Toll-like receptor (TLR) ligands such as lipopolysaccharide (LPS) purified from Escherichia coli or C. trachomatis L2 prior to infection greatly enhanced secretion of IL-1β from these cells. By using LPS-primed macrophages as a model system, it was determined that IL-1β secretion was dependent on caspase-1, potassium efflux, and the activity of serine proteases. Significantly, chlamydia-induced IL-1β secretion in macrophages required bacterial viability but not growth. Our findings demonstrate that IL-1β secreted by macrophages and neutrophils has important effects in vivo during chlamydial infection. Additionally, prestimulation of macrophages by chlamydial TLR ligands may account for the elevated levels of pro-IL-1β mRNA observed in vivo in this cell type.The obligate intracellular pathogen Chlamydia trachomatis is the most common cause of sexually transmitted infection worldwide. Infection can lead to oviduct pathology and infertility in females. Cells respond to infection with C. trachomatis by upregulating a wide assortment of genes, including those for proinflammatory cytokines such as tumor necrosis factor alpha, interleukin-1β (IL-1β), and IL-6 (34, 54, 55, 68). The cellular paradigm of chlamydial pathogenesis states that tissue damage resulting from chlamydial infection is caused by excessive production of these proinflammatory cytokines (61). In support of this theory, caspase-1 knockout (KO) and Toll-like receptor 2 (TLR2) KO mice exhibit less upper genital tract pathology than wild-type (WT) mice, despite equivalent courses of infection (12, 15). This finding is noteworthy because caspase-1 KO mice lack the protease required to activate IL-1β (32) and TLR2 KO fibroblasts express less mRNA for IL-1β and lower levels of other inflammatory cytokines than WT fibroblasts during in vitro chlamydial infections (15). Additionally, administration of an IL-1β antagonist prevents C. trachomatis-induced cytotoxicity in a human fallopian tube organ culture model (30). Overall, these observations suggest that IL-1β may be a potentially important factor in the development of oviduct pathology, underscoring the need to define the role of IL-1β during in vivo chlamydial infections and to mechanistically determine how the IL-1β-converting enzyme caspase-1 is activated upon contact with Chlamydia spp. to produce mature IL-1β.Caspase-1 is the central component of the host “inflammasome” (reviewed in reference 38) and exists at rest as a 45-kDa zymogen. When activated by proteolysis, it forms a tetramer consisting of two 10- to 20-kDa heterodimers (65), with the 20-kDa portion containing the active-site cysteine necessary to cleave the cytokine precursors pro-IL-1β and pro-IL-18 and also the TH2 cytokine precursor pro-IL-33 (10, 24, 59, 63). Caspase-1 has many other substrates in the cell (60), but its two main targets relevant to inflammation are IL-1β (10) and IL-18 (24). Both IL-1β and IL-18 require this processing for biologic activity. IL-18 plays a role in stimulating gamma interferon production from T cells (18, 56) and natural killer cells (11), suggesting a protective role for IL-18 during genital chlamydial infection. This leads to the theory that the detrimental role of caspase-1 for oviduct pathology during chlamydial infection is mediated mainly via overproduction of the proinflammatory cytokine IL-1β.Several studies have shown that caspase-1 activation during intracellular bacterial infection involves active contribution from the bacteria. For instance, activation occurs following bacterial type III secretion (T3S)-dependent introduction into the cytosol of Yersinia pestis YopJ (35), Pseudomonas aeruginosa flagellin (42), or Salmonella enterica flagellin (20). Early work examining the role of caspase-1 during chlamydial infection by using HeLa cells demonstrated that the activation of caspase-1 late in the infection cycle (36 to 48 h postinfection) is dependent on both chlamydial viability and protein synthesis (36). Additionally, the T3S antagonist INP0007 prevents activation of caspase-1 in C. trachomatis-infected HeLa cells (66). Low-level production of IL-1β was abolished in caspase-1 KO mouse peritoneal macrophages infected in vitro with mouse chlamydia C. muridarum (12), which can replicate effectively in mouse macrophages (46). However, it is not known if the infected epithelial cells or the inflammatory cells recruited to the site of infection are the main producers of IL-1β during an in vivo genital infection. Furthermore, the specific role for IL-1β during in vivo genital infection has not been addressed. In this study, we show that IL-1β is required for optimal chlamydial clearance but also contributes to the development of genital tract pathology. Additionally, macrophages and neutrophils and not epithelial cells account for the high expression levels of IL-1β in vivo. We further describe mechanistic details of IL-1β production by using in vitro infections of lipopolysaccharide (LPS)-primed macrophages. Overall, these macrophages produced IL-1β by both caspase-1- and serine protease-dependent mechanisms, but surprisingly, IL-β secretion by these cells occurred in a bacterial protein synthesis-independent manner, although chlamydial viability was required.     

Nickel Induces Interleukin-1β Secretion via the NLRP3–ASC–Caspase-1 Pathway

Exposure to nickel (Ni²⁺) can trigger allergic reactions in susceptible individuals, which is widely accepted as the major cause of allergic contact hypersensitivity (CHS) worldwide. Although Ni²⁺-induced proinflammatory responses clearly play a pivotal role in CHS, the underlying molecular mechanism has not been fully defined. Here we report that Ni²⁺ activates the NLRP3–ASC–caspase-1 immune signaling pathway in antigen-presenting cells, leading to the proteolytic processing and secretion of a proinflammatory cytokine, interleukin-1β (IL-1β). The activation of this signaling axis is independent of phagolysosome–cathepsin B pathway. Instead, Ni²⁺ induces mitochondrial reactive oxygen species accumulation and cation fluxes, both of which are required for activating the NLRP3–ASC–caspase-1 pathway. Together, these results identified a novel innate immune signaling pathway (NLRP3–ASC–caspase-1–IL-1β) activated by Ni²⁺ and provided a mechanistic basis for optimizing the therapeutic intervention against Ni²⁺-induced allergy in patients.     

Interleukin-1β induces expression of cyclooxygenase-2 mRNA in human gingival fibroblasts

The effect of interleukin-1 (IL-1) on the expression of cyclooxygenase-1 and –2 (COX-1 and COX-2) mRNA and its relation to prostaglandin E₂ (PGE₂) biosynthesis in human gingival fibroblasts was studied. IL-1 increased levels of mRNA for COX-2 whereas the COX-1 mRNA level was unaffected. The increased COX-2 mRNA levels were accompanied by enhanced PGE₂ formation. The phorbol, 12-myristate 13-acetate (PMA), known to stimulate protein kinase C (PKC), also induced expression of COX-2 mRNA. When gingival fibroblasts were treated simultaneously with IL-1 and PMA, the cytokine IL-1 synergistically increased levels of COX-2 mRNA, accompanied by a corresponding increase in PGE₂ biosynthesis. The anti-inflammatory steroid, dexamethasone (DEX) abolished the enhanced expression of COX-2 mRNA as well as PGE₂ formation induced by IL-1, PMA or the combination of IL-1 and PMA. The study indicates that the IL-1 induced PGE₂ formation is mediated by an enhanced gene expression of COX-2 in gingival fibroblasts suggesting that the enzyme COX-2 may play an important role in the regulation of prostanoid formation at inflammatory lesions in gingival tissue.     

Gender-related Distribution of the Interleukin-1β and Interleukin-1 Receptor Antagonist Gene Polymorphisms in Patients with End-stage Liver Disease

Interleukin-1β (IL-1β) genetic polymorphisms and IL-1 receptor antagonist (IL1RN) variable number tandem repeat (VNTR) seem to be related with the occurrence of chronic diseases. This study aimed to verify whether IL-1β -511>C/T, -31>T/C, +3953>C/T and IL1RN VNTR were associated to the development of liver cirrhosis. Two hundred forty cirrhotic patients were involved in the study. A significant trend was detected, for increasing cirrhosis frequencies, grouping the patients as follows: females and males carrying neither the IL-1β (-511 -31) T-C/T-C or T-C/(T-T or C-C) diplotypes nor any IL1RN A2 allele (138/292), males carrying either the IL-1β T-C/T-C or T-C/(T-T or C-C) diplotypes or at least one IL1RN A2 allele (74/147) and males carrying either the IL-1β T-C/T-C or T-C/(T-T or C-C) diplotypes and at least one IL1RN A2 allele (28/37) (p?<?0.01). IL-1β polymorphisms are associated with the occurrence of end stage liver disease. IL-1β inflammatory activity appears more pronounced in males.     

Interleukin-1β of Red nucleus involved in the development of allodynia in spared nerve injury rats

Previous studies have indicated that interleukin-1β (IL-1β) is involved not only in immune modulation, but also in the modulation of pain in both the peripheral and central nervous systems. The current study investigated the expression of IL-1β in the brain of rats with spared nerve injury (SNI), using immunohistochemical technique. The results showed that immunoreactive-like IL-1β protein was significantly elevated in the Red nucleus (RN) 2 weeks after SNI. To further study the function of IL-1β in RN, different doses of IL-1β neutralizing antibody (10, 1.0 and 0.1 ng) were microinjected into the RN contralateral to the nerve injury side of neuropathic rats. The results indicated that the higher doses of anti-IL-1β antibody (10 and 1.0 ng) significantly attenuated the mechanical allodynia of neuropathic rats. However, administration of 0.1 ng anti-IL-1β antibody did not show anti-allodynia effect. These results suggest that IL-1β of RN is involved in the development of neuropathic pain in SNI rats.     

Interleukin-1β in innate inflammation,autophagy and immunity

Although IL-1β is the master inflammatory cytokine in the IL-1 family, after more than ten years of continuous breeding, mice deficient in IL-1β exhibit no spontaneous disease. Therefore, one concludes that IL-1β is not needed for homeostasis. However, IL-1β-deficient mice are protected against local and systemic inflammation due to live infections, autoimmune processes, tumor metastasis and even chemical carcinogenesis. Based on a large number of preclinical studies, blocking IL-1β activity in humans with a broad spectrum of inflammatory conditions has reduced disease severity and for many, has lifted the burden of disease. Rare and common diseases are controlled by blocking IL-1β. Immunologically, IL-1β is a natural adjuvant for responses to antigen. Alone, IL-1β is not a growth factor for lymphocytes; rather in antigen activated immunocompetent cells, blocking IL-1 reduces IL-17 production. IL-1β markedly increases in the expansion of naive and memory CD4T cells in response to challenge with their cognate antigen. The response occurs when only specific CD4T cells respond to IL-1β and not to IL-6 or CD-28. A role for autophagy in production of IL-1β has emerged with deletion of the autophagy gene ATG16L1. Macrophages from ATG16L1-deficient mice produce higher levels of IL-1β after stimulation with TLR4 ligands via a mechanism of caspase-1 activation. The implications for increased IL-1β release in persons with defective autophagy may have clinical importance for disease.     

Overexpression of ERβ inhibits the proliferation through regulating TNG-β signaling pathway in osteosarcoma

The present study aimed to explore the potential anti-tumor effect of ERβ overexpression and investigate its related mechanism in osteosarcoma. Cell cycle and apoptosis rates were measured by flow cytometry. Cell proliferation and formation of autophagosome were assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and dansylcadaverine (MDC) staining assay. Cell migration and invasion were detected by wound healing assay and transwell assay. Western blot analysis was designed to detect the protein expressions of surviving, Bax, LC-3 П, Beclin-1, ERβ, TβRⅠ, TβRⅡ, Smad2, Smad3 and Smad7. Real-Time fluorogenic PCR was designed to examine the mRNA expressions of surviving, Bax, ERβ, TβRⅠ, TβRII, Smad2, Smad3 and Smad7. The results showed that ERβ overexpression inhibited cell proliferation, migration and invasion, blocked cell cycle, and induced apoptosis and autophagy. Additionally, ERβ overexpression significantly inhibited the expression of surviving, TβRⅠ, TβRⅡ, Smad2 and Smad3. Meanwhile, the expressions of Bax, LC-3 П, Beclin-1 and Smad7 were dramatically upregulated by ERβ overexpression. In conclusion, ERβ overexpression could inhibit cell proliferation, migration and invasion, block cell cycle, and promote apoptosis and autophagy in OS by downregulating TNG-β signaling pathway.     

Effect of Interleukin-1β on Lipid Peroxidation in Emotiogenic Structures of the Brain in Rats during Acute Stress

We studied the effects of immunomodulatory cytokine interleukin-1β on lipid peroxidation in emotiogenic structures of the brain (hypothalamus, sensorimotor cortex, and amygdala) of behaviorally active and passive rats with different prognostic resistance to stress. Immobilization of animals with simultaneous electrocutaneous stimulation (1 h) served as the model of acute emotional stress. Intraperitoneal injection of IL-1β (5 μg/kg) was followed by accumulation of malonic dialdehyde (end-product of lipid peroxidation) in all structures of the brain in passive rats, as well as in the hypothalamus of active animals. As differentiated from active rats, stress exposure in passive specimens was accompanied by a selective increase in malonic dialdehyde content in the sensorimotor cortex and amygdala. Pretreatment with IL-1β prevented activation of lipid peroxidation in the studied structures of the brain in passive rats after stress exposure. Our results show the specifi c effect of IL-1β on free-radical processes in the hypothalamus, sensorimotor cortex, and amygdala in rats with various behavioral parameters. Regional features of lipid peroxidation in emotiogenic structures of the brain in animals with different emotional reactivity probably contribute to the existence of signifi cant variations in the individual resistance to emotional stress.     

A Two Step Purification of Recombinant Human Interleukin-1β Expressed in E. Coli

Recombinant human interleukin-1β has been expressed in high yield using E. coli with a cDNA clone obtained from SKhep1RNA. The rIL-1β is purified to apparent homogeneity using freeze-thaw extractions followed by hydrophobic interaction chromatography over phenyl Sepharose. The procedure can provide pure rIL-1β (up to 15 mg per liter of E. coli culture) without the use of denaturants and if desired, in the absence of column chromatographic steps. Purity is defined by the presence of a single band on 1-D polyacrylamide gels and a single spot on 2-D polyacrylamide gels. The purified protein exhibits a biological activity of 1 × 10⁷ units/mg in a fibroblast proliferation assay and is shown to cross-react with rabbit anti-human IL-1β sera.     

Effect of Interleukin-1β on the Expression of Tight Junction Proteins in the Culture of HaCaT Keratinocytes

We studied the effect of IL-1β on the expression of tight junction proteins (occludin and claudins) in cultured HaCaT keratinocytes and changes of transepithelial resistance. Addition of IL-1β had little effect on transepithelial resistance, increased the expression of claudin-1, and did not modify the expression of occludin. In other tissues, IL-1β also increases claudin-1 expression, but significantly decreases occludin expression. These changes are accompanied by the reduction of transepithelial resistance. The IL-1β-induced increase in the expression of claudin-1 in cultured HaCaT keratinocytes simulates the appearance of claudin-1 at the early stage of skin wound healing. It is accompanied by an increase in IL-1β concentration in the wound fluid.     

IL‐1β Induces and TGF‐β Reduces Vitamin D3‐Induced Bone Resorption in Mouse Calvarial Bone Cells

Bone cells produce multiple growth factors and cytokines that have effects on bone metabolism and can be incorporated into the bone matrix. The present study was designed to extend these observations by examining the interactions between transforming growth factor‐β (TGF‐β) or interleukin‐1β (IL‐1β) and bone cells in a rat long bone culture model. IL‐1β regulates several activities of the osteoblast cells derived from rat long bone explants in vitro. IL‐1β stimulated cellular proliferation and the synthesis of prostaglandin E₂ and plasminogen activator activity in the cultured cells in a dose‐dependent manner. TGF‐β is present in the bone matrix and potentially can be released during bone resorption. TGF‐β reduced basal bone resorption and inhibited vitamin D₃ [1,25(OH)₂D₃]‐induced bone resorption in rat long bone cells. These studies support the role of IL‐1β in the pathological modulation of bone cell metabolism, with regard to implication in the pathogenesis of osteoporosis by IL‐1β, and that TGF‐β is positively inhibiting the bone resorption.     

Effect of Interleukin-1β on the Behavior of Rats during Mild Stress in the Open-Field Test

We studied the effect of interleukin-1β on the behavior of rats with different individual typological characteristics during mild stress in the open-field test. Intraperitoneal injection of interleukin-1β (5 μg/kg, 108 U/mg) was followed by a decrease in orientation and exploratory activity of passive and, particularly, of active animals in the open field. As differentiated from rats receiving physiological saline, the initial differences in behavioral characteristics of active and passive animals were not revealed in the repeated test after injection of interleukin-1β. We conclude that interleukin-1β abolishes the behavioral differences between active and passive specimens in the open field. These data suggest that administration of interleukin-1β to rats leads to reorganization of the mechanisms for emotional evaluation of adverse emotiogenic factors under conditions of mild stress in the open-field test.