Kinetics of IL1 beta mRNA and protein accumulation in human mononuclear cells

Unconventional Protein Secretion in Brain Tumors Biology: Enlightening the Mechanisms for Tumor Survival and Progression

Non-canonical secretion pathways, collectively known as unconventional protein secretion (UPS), are alternative secretory mechanisms usually associated with stress-inducing conditions. UPS allows proteins that lack a signal peptide to be secreted, avoiding the conventional endoplasmic reticulum-Golgi complex secretory pathway. Molecules that generally rely on the canonical pathway to be secreted may also use the Golgi bypass, one of the unconventional routes, to reach the extracellular space. UPS studies have been increasingly growing in the literature, including its implication in the biology of several diseases. Intercellular communication between brain tumor cells and the tumor microenvironment is orchestrated by various molecules, including canonical and non-canonical secreted proteins that modulate tumor growth, proliferation, and invasion. Adult brain tumors such as gliomas, which are aggressive and fatal cancers with a dismal prognosis, could exploit UPS mechanisms to communicate with their microenvironment. Herein, we provide functional insights into the UPS machinery in the context of tumor biology, with a particular focus on the secreted proteins by alternative routes as key regulators in the maintenance of brain tumors.

Calcific tendonitis of the rotator cuff: From formation to resorption

Calcific tendonitis of the rotator cuff is due to apatite deposits in the shoulder tendons. Patients affected by calcific tendonitis have chronic shoulder pain and disability. Although the disease is frequent, about 10 to 42% of painful shoulders, mechanisms leading to this pathological mineralization are still largely unknown. Research reported in the 1990s suggested that the formation of calcific deposits is linked to cells looking like chondrocytes identified around calcium deposits within a fibrocartilage area. They were considered to be derived from tenocytes but more recently, tendon stem cells, able to differentiate into chondrocytes, were isolated. The pro-mineralizing properties of these chondrocytes-like cells, especially the role of alkaline phosphatase, are not currently clarified. The calcium deposits contain poorly crystalline carbonated apatite associated with protein. Among these proteins, only osteopontin has been consistently identified as a potential regulating factor. During the disease, spontaneous resorption can occur with migration of apatite crystals into the subacromial bursa causing severe pain and restriction of movement. In in vivo and in vitro experiments, apatite crystals were able to induce an influx of leucocytes and a release of IL-1β and IL-18 through the activation of the NLRP3 inflammasome. However, mechanisms leading to spontaneous resolution of this inflammation and disappearance of the calcification still need to be elucidated.

Intracellular innate immunity in gouty arthritis: role of NALP3 inflammasome

Gout is an inflammatory disease caused by the deposition of monosodium urate (MSU) crystals in the joint. Recent studies have significantly advanced our knowledge on the understanding of mechanisms underlying MSU crystal-induced inflammation. MSU crystals act as a 'danger signal' that can be recognized by pattern recognition receptors both at cell surface and cytoplasm, indicating the importance of innate immunity in gout. This review focuses on the critical role of intracellular NALP3 inflammasome in MSU crystal-induced inflammation.

Effects of caspase inhibition on the progression of experimental glomerulonephritis

BACKGROUND

Caspase-3 has a central role in the execution of apoptosis. In a nephrotoxic nephritis (NTN) model, we previously demonstrated an up-regulation of caspase-3 that was associated with inappropriate renal apoptosis, inflammation, tubular atrophy, and renal scarring.

METHODS

We applied a pan caspase inhibitor, Boc-Asp (OMe)-fluoro-methyl-ketone (B-D-FMK), directly to rat NTN kidney using an intrarenal cannula fed from an osmotic pump. Animals were treated either for the first 7 days (acutely) to determine the effects on renal inflammation (ED-1 staining) and apoptosis (in situ end labeling of fragmented DNA), or for 28 days commencing 15 days after NTN (chronically) to observe the effects on cell death and renal fibrosis. Changes of caspase-3 and caspase-1 activity were detected by fluorometric substrate cleavage assay. Changes in caspase-3 and caspase-1, interleukin-1 beta (IL-1 beta), and collagen I, III, and IV proteins and mRNA were detected by Western blotting and Northern blotting, respectively.

RESULTS

In both treated groups, caspase-3 activity was inhibited, and 17 and 24 kD active caspase-3 proteins were reduced significantly. A compensatory increase of caspase-3 mRNA occurred in the acutely treated group, but decreased in the chronically treated group (P < 0.05). Although there were no significant changes in caspase-1 activity and its active protein, the observed decrease in its precursor in the chronic group was increased by treatment (P < 0.05). Further, IL-1 beta precursor and its mRNA were significantly reduced by treatment only in the chronically treated group. Apoptosis was decreased in the glomeruli of acutely treated rats, and in the tubules and interstitium of chronically treated animals (P < 0.05). Glomerular inflammation was decreased only in the acutely treated group, whereas tubulointerstitial inflammation was lowered in both treated groups (P < 0.05). Glomerulosclerosis was reduced in both inhibitor groups, with a reduction in tubulointerstitial fibrosis and collagen I, III, and IV mRNA restricted to chronically treated animals (P < 0.05). Proteinuria was significantly decreased with caspase inhibition in both treated groups, but not serum creatinine level.

CONCLUSION

This study clearly indicates that caspase inhibition reduces renal apoptosis, ameliorates inflammation and fibrosis, and improves proteinuria in experimental glomerulonephritis, which may mainly be related to changes in the caspase enzymatic system.

Bovine interleukin-1 expression by cultured mammary epithelial cells (MAC-T) and its involvement in the release of MAC-T derived interleukin-8

MAC-T cells, an established bovine mammary epithelial cell line, were utilized to investigate both expression of interleukin-1 (IL-1) mRNA and secretion of IL-1 after Escherichia coli lipopolysaccharide (E. coli LPS) stimulation. In addition, recombinant human IL-1beta, recombinant human IL-1 receptor antagonist (IL-1ra) and a neutralizing goat antibody against type I human IL-1 receptor were used to study the involvement of IL-1 in the release of IL-8. The expression of MAC-T derived IL-1alpha mRNA was correlated to production of IL-1alpha protein as measured by an IL-1alpha sandwich ELISA. Secretion of IL-1alpha was dose- and time-dependent, with a maximal level of 600 pg/ml detectable upon 2-h stimulation with 20 microg of LPS per ml. IL-1ra and the neutralizing antibody significantly blocked the ability of IL-1beta to stimulate secretion of IL-8 by MAC-T cells. During this study, we have demonstrated that MAC-T cells secrete IL-1 in response to LPS stimulation and IL-1 is an important mediator for the release of the bovine IL-8 by MAC-T cells. These results further indicate the potential importance of mammary epithelial cells as a source of immunoregulation in the mammary gland via cytokine elaboration.

Endothelial activation in monosodium urate monohydrate crystal-induced inflammation: in vitro and in vivo studies on the roles of tumor necrosis factor alpha and interleukin-1

OBJECTIVE

There is relatively little direct evidence for the roles of interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha) in activating endothelium in vivo. The aim of this study was to use in vitro and in vivo models to investigate the contribution of these cytokines to both E-selectin expression and the recruitment of polymorphonuclear cells (PMN) in monosodium urate monohydrate (MSU) crystal-induced inflammation.

METHODS

MSU crystals were incubated with freshly isolated mononuclear cells, after which the harvested supernatants were tested for their ability to induce E-selectin expression during coculture with human umbilical vein endothelial cells. Subsequent experiments were performed with the addition of neutralizing anticytokine antibodies/antisera. The role of TNF alpha was then studied in an MSU crystal-induced monarthritis model, in the presence or absence of anti-TNF alpha (5 mg/kg intravenously). 99mtechnetium (99mTc)-labeled PMN cells and (111)indium (111In)-labeled anti-E-selectin monoclonal antibody (MAb) 1.2B6 were intravenously administered 4 hours after intraarticular injection to quantify PMN recruitment and E-selectin expression in inflamed joints.

RESULTS

MSU crystals were a potent stimulus for IL-1 and TNF alpha production by monocytes in vitro, and these cytokines fully accounted for MSU crystal-stimulated, monocyte-mediated endothelial activation. In the MSU crystal-induced monarthritis model, TNF alpha blockade was very effective in suppressing both E-selectin expression and PMN emigration into the inflamed joints, as judged by gamma-camera image analysis and postmortem tissue counting following the intravenous injection of 99mTc-PMN and 111In-anti-E-selectin MAb.

CONCLUSION

IL-1 and TNF alpha appear to be the only factors released by monocytes following incubation with MSU crystals, which induce E-selectin expression in vitro. Anti-TNF alpha is effective in suppressing endothelial activation and PMN recruitment in vivo E-selectin imaging can be used to assess the endothelial response to therapy and may prove useful for clinical studies.

Effect of sulfur dioxide on cytokine production of human alveolar macrophages in vitro

Tumor necrosis factor-alpha, interleukin-1beta, interleukin-6, and transforming growth factor-beta are cytokines synthesized by alveolar macrophages. We investigated the effect of sulfur dioxide, a major air pollutant, on the production of these cytokines by alveolar macrophages. The cells were layered on a polycarbonate membrane and exposed for 30 min to 0.0, 1.0, 2.5, and 5.0 ppm sulfur dioxide at 37 degrees C and 100% air humidity. The cells were incubated for 24 h after exposure, thus allowing cytokine release. Cytotoxic effects of sulfur dioxide were evaluated by trypan blue exclusion. Cytokines were measured with enzyme-linked immunosorbent assays (i.e., tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6) or by use of a specific bioassay (i.e., transforming growth factor-beta). The toxicity of sulfur dioxide for alveolar macrophages ranged from 3.1 % to 9.5 %. A 30-min exposure to sulfur dioxide induced a significant decrease in spontaneous and lipopolysaccharide-stimulated tumor necrosis factor-alpha (p < .001) and lipopolysaccharide-stimulated interleukin-1beta release (p < .05). The release of interleukin-6 and transforming growth factor-beta was not affected significantly by sulfur dioxide exposure. Our results demonstrated a functional impairment of alveolar macrophages after sulfur dioxide exposure (i.e., release of tumor necrosis factor-alpha and interleukin-1beta). Neither spontaneous nor stimulated release of interleukin-6 and transforming growth factors were influenced by exposure to sulfur dioxide.

Interleukin-1 beta converting enzyme in murine Langerhans cells and epidermal-derived dendritic cell lines

Interleukin (IL)-1 beta plays an essential role in the induction of T cell-mediated immune responses in skin. Langerhans cells (LC), which constitutively express IL-1 beta mRNA, have been assumed to be the primary source of IL-1 beta in murine epidermis. The purpose of this study was to determine whether LC express mRNA for the IL-1 beta converting enzyme (ICE), a protease that is required for processing pro-IL-1 beta into an active form. Here, we report that both IL-1 beta and ICE mRNA are expressed by the Ia+ population (i.e. LC) in murine epidermis. Moreover, murine epidermal-derived DC lines (XS series) also express both IL-1 beta and ICE mRNA, and they secrete relatively large amounts of IL-1 beta following lipopolysaccharide (LPS) stimulation. Finally, LPS-triggered IL-1 beta secretion by XS cells is blocked almost completely by the ICE inhibitor acetyl-Tyr-Val-Ala-Asp-CH2OC(O)-[2,6-(CF3)2]Ph. These results demonstrate that LC are the primary source of IL-1 beta within the epidermis, and suggest that the proinflammatory role of IL-1 beta may be regulated pharmacologically by ICE inhibitors in vivo.

Modulation of interleukin-1 secretion by immunosuppressive drugs, alone and in combination

This study evaluates the ability of the immunosuppressive drugs dexamethasone, cyclosporine, FK506 and rapamycin, alone and in combination to suppress interleukin-1 beta (IL-1 beta) secretion in vitro by THP-1 cells when stimulated by lipopolysaccharide. All four drugs, when added to cell culture medium at therapeutic concentrations, significantly decrease secretion of the monokine to well below control levels. However, only dexamethasone completely suppresses IL-1 beta secretion in a dose-dependent fashion. Cyclosporine, FK506 and rapamycin only partially suppress secretion of IL-1 beta at concentrations within their therapeutic ranges and increasing concentrations of the drugs do not result in further suppression of secretion. Likewise, the combination of any two of these three drugs does not provide any additional suppressive effect. Dexamethasone, however, when added in increasing concentrations in combination with any of the other drugs, results in further suppression of IL-1 secretion in a dose-dependent fashion. These data suggest that cyclosporine, FK506 and rapamycin all share a common effect on the production of IL-1 beta, different from that of dexamethasone.

Interleukin-1 and its inhibitors: implications for disease biology and therapy

IL-1 alpha and IL-1 beta are polypeptide hormones that exhibit a broad spectrum of beneficial and harmful biologic activities. Clinical trials designed to benefit from its stimulatory effects on human hematopoiesis and from its role in improving host defenses, are being currently conducted. Other in vivo studies, using IL-1 inhibitors with an attempts to block the detrimental effects of IL-1, are underway. Because of the multifunctional effects of IL-1 in human physiology and its pathogenetic role in several diseases, the capability to control the effects of IL-1 may prove to be a useful tool in medical practice.

In situ hybridization of interleukin-1 in CD14-positive cells in rheumatoid arthritis

Interleukin 1 (IL-1) has been implicated as an inflammatory mediator in rheumatoid arthritis (RA). Many cell types, including macrophages, lymphocytes, fibroblasts, and endothelial cells, can produce IL-1 and it is known that IL-1 production is under transcriptional control. It has, however, been difficult to define in vivo the predominant cellular source of this mediator in RA. Here, we have used the combination of in situ hybridization of mRNA and cellular immunophenotyping with monoclonal antibodies to show that the IL-1 beta gene is expressed predominantly by CD14-positive macrophages in synovial tissue from patients with RA. Synovial macrophages were also associated with the immunoreactive IL-1 peptide. These cells appear to be the major source of IL-1 beta within the rheumatoid synovium in vivo and must be regarded as playing a central role in the chronic inflammation and joint destruction of RA.