Reactive nitrogen and oxygen species in interleukin-1-mediated DNA damage associated with osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is associated with increased levels of reactive nitrogen and oxygen species and pro-inflammatory cytokines, such as interleukin-1 (IL-1). Nitric oxide (NO) can mediate a number of the catabolic effects of IL-1 in articular cartilage. The aims of this study were to determine if OA cartilage shows evidence of DNA damage, and if IL-1 could induce DNA damage in non-OA cartilage by increasing NO or superoxide.

METHODS

Articular chondrocytes were isolated from porcine femoral condyles and embedded in 1.2% alginate. The effects of 24h incubation with IL-1, the nitric oxide synthase 2 (NOS2)-selective inhibitor, the free radical scavenger superoxide dismutase (SOD), the NO donor NOC18, or the combined NO and peroxynitrite donor SIN-1 on DNA damage were tested, using the "comet" assay. NO production was measured using the Griess assay. The type of oxidative damage present was assessed using a modified comet assay.

RESULTS

OA cartilage had significantly more DNA damage than non-OA cartilage (P<0.001). IL-1 caused an increase in DNA damage (P<0.01), which was associated with increased NO production (P<0.01). Both oxidative DNA strand breaks and base modifications of purines and pyrimidines were observed. IL-1-induced DNA damage was inhibited by an NOS2 inhibitor or by SOD (P<0.01). Furthermore, NOC18 or SIN-1 caused DNA damage (P<0.001).

CONCLUSION

Our work shows chondrocytes in osteoarthritic cartilage exhibit DNA damage, and that IL-1 induces DNA damage and reactive oxygen and nitrogen species in non-OA chondrocytes in alginate.

Hyaluronan inhibits expression of ADAMTS4 (aggrecanase-1) in human osteoarthritic chondrocytes

BACKGROUND

Intra-articular injection of hyaluronan (HA) has been suggested to have a disease-modifying effect in osteoarthritis, but little is known about the possible mechanisms.

OBJECTIVE

To investigate the effects of HA species of different molecular mass, including 800 kDa (HA800) and 2700 kDa (HA2700), on the expression of aggrecanases (ie, ADAMTS species), which play a key role in aggrecan degradation.

METHODS

The effects of HA species on the expression of ADAMTS1, 4, 5, 8, 9 and 15 in interleukin 1alpha (IL1alpha)-stimulated osteoarthritic chondrocytes were studied by reverse transcription PCR and real-time PCR. Expression of ADAMTS4 protein and aggrecanase activity and signal transduction pathways of IL1, CD44 and intracellular adhesion molecule 1 (ICAM1) were examined by immunoblotting.

RESULTS

IL1alpha treatment of chondrocytes induced ADAMTS4, and HA800 and HA2700 significantly decreased IL1alpha-induced expression of ADAMTS4 mRNA and protein. IL1alpha-stimulated aggrecanase activity in osteoarthritic chondrocytes was reduced by treatment with HA2700 or transfection of small interfering RNA for ADAMTS4. A similar result was obtained when HA2700 was added to explant cultures of osteoarthritic cartilage. HA2700 neither directly inhibited nor bound to ADAMTS4. Downregulation of ADAMTS4 expression by HA2700 was attenuated by treatment of IL1alpha-treated chondrocytes with antibodies to CD44 and/or ICAM1. The increased phosphorylation of IL1 receptor-associated kinase-1 and extracellular signal-regulated protein kinase1/2 induced by the IL1alpha treatment was downregulated by enhanced IRAK-M expression after HA2700 treatment.

CONCLUSION

These data suggest that HA2700 suppresses aggrecan degradation by downregulating IL1alpha-induced ADAMTS4 expression through the CD44 and ICAM1 signalling pathways in osteoarthritic chondrocytes.

Inhibition of keratinocyte differentiation by the synergistic effect of IL-17A, IL-22, IL-1α, TNFα and oncostatin M

Keratinocyte differentiation program leading to an organized epidermis plays a key role in maintaining the first line of defense of the skin. Epidermal integrity is regulated by a tight communication between keratinocytes and leucocytes, particularly under cytokine control. Imbalance of the cytokine network leads to inflammatory diseases such as psoriasis. Our attempt to model skin inflammation showed that the combination of IL-17A, IL-22, IL-1α, OSM and TNFα (Mix M5) synergistically increases chemokine and antimicrobial-peptide expression, recapitulating some features of psoriasis. Other characteristics of psoriasis are acanthosis and down-regulation of keratinocyte differentiation markers. Our aim was to characterize the specific roles of these cytokines on keratinocyte differentiation, and to compare with psoriatic lesion features. All cytokines decrease keratinocyte differentiation markers, but IL-22 and OSM were the most powerful, and the M5 strongly synergized the effects. In addition, IL-22 and OSM induced epidermal hyperplasia in vitro and M5 induced epidermal thickening and decreased differentiation marker expression in a mouse model, as observed in human psoriatic skin lesions. This study highlights the precise role of cytokines in the skin inflammatory response. IL-22 and OSM more specifically drive epidermal hyperplasia and differentiation loss while IL-1α, IL-17A and TNFα were more involved in the activation of innate immunity.

Activation of focal adhesion kinase enhances the adhesion and invasion of pancreatic cancer cells via extracellular signal-regulated kinase-1/2 signaling pathway activation

BACKGROUND

Interaction with integrin and focal adhesion kinase (FAK) regulates the cancer cell adhesion and invasion into extracellular matrix (ECM). In addition, phosphorylation of FAK correlates with the increase of cell motility and invasion. Adhesion and spreading of cancer cells on a variety of ECM proteins, including collagen type IV (Coll IV), leads to an increase in tyrosine phosphorylation and activation of FAK. In this study, we investigated the mechanism of activation of FAK and its downstream extracellular signal-regulated kinase (ERK)-1/2 signaling following stimulation by interleukin (IL)-1alpha and adhesion to ECM with subsequent enhancement of pancreatic cancer cell adhesion and invasion.

RESULTS

In immunoblotting analysis, all three pancreatic cancer cell lines (AsPC-1, BxPC-3, and Capan-2) expressed the protein of FAK and beta1 integrin. Enhancement of FAK protein association with beta1 integrin when cells were plated on Coll IV was more increased by stimulation with IL-1alpha. Preincubation with anti-beta1 integrin antibody and FAK siRNA transfection inhibited the association of FAK with beta1 integrin of pancreatic cancer cells. FAK phosphorylation was observed by adhesion to Coll IV, furthermore, stronger FAK phosphorylation was observed by stimulation with IL-1alpha of pancreatic cancer cells adhered to Coll IV in time-dependent manner. Genistein, a tyrosine kinase inhibitor, markedly inhibited the FAK phosphorylation. IL-1alpha stimulation and Coll IV adhesion enhanced the activation of Ras, as evidenced by the increased Ras-GTP levels in pancreatic cancer cells. Activation of Ras correlated with the phosphorylation of ERK. While not statistical affecting the apoptosis of pancreatic cancer cells, IL-1alpha-induced adhesion and invasion on Coll IV were inhibited with FAK gene silencing by siRNA, beta1 integrin blocking, and inhibition of FAK phosphorylation. PD98059, a MEK inhibitor, also inhibited IL-1alpha-induced enhancement of adhesion and invasion in pancreatic cancer cells.

CONCLUSION

Our results demonstrated that activation of FAK is involved with the aggressive capability in pancreatic cancer through Ras/ERK signaling pathway. Based on our results, we suggest that the modification of IL-1, FAK, and integrins functions might be a novel therapeutic approach to aggressive spread of pancreatic cancer.

UVB and proinflammatory cytokines synergistically activate TNF-alpha production in keratinocytes through enhanced gene transcription

UVB irradiation potently induces cytokines in the skin, including IL-1alpha and tumor necrosis factor-alpha (TNF-alpha). The mechanism for TNF-alpha induction in UVB-irradiated keratinocytes is not clear. In this study, we explored the effects of UVB and cytokines, alone or in combination in human keratinocytes. Keratinocytes were sham- or UVB-irradiated with 30 mJ cm(-2), and then incubated in the absence or presence of IFN-alpha2b, TNF-alpha, or IL-1alpha. UVB and IL-1alpha treatment synergistically enhanced TNF-alpha secretion and mRNA levels in human keratinocytes, similar to the findings reported previously in human fibroblasts. Exogenous recombinant TNF-alpha up-regulates its own mRNA level. However, addition of IFN-alpha2b did not show any additive effect on TNF-alpha mRNA induction. To understand the regulation of TNF-alpha mRNA by UVB, with or without IL-1alpha, we examined the transcription rate and half-life of TNF-alpha mRNA. Treatment of keratinocytes with IL-1alpha or UVB alone increased TNF-alpha gene transcription 4- to 5-fold over sham treatment, and TNF-alpha gene transcription increased 11-fold in cells treated with UVB plus IL-1alpha over sham. UVB with IL-1alpha did not enhance the half-life of TNF-alpha mRNA over that seen with UVB alone. In conclusion, TNF-alpha expression in primary keratinocytes is upregulated transcriptionally by UVB and IL-1alpha.

Interleukin-1alpha stimulates proinflammatory cytokine expression in human cardiac myofibroblasts

Cardiac myofibroblasts (CMF) play a key role in infarct repair and scar formation following myocardial infarction (MI) and are also an important source of proinflammatory cytokines. We postulated that interleukin-1alpha (IL-1alpha), a potential early trigger of acute inflammation post-MI, could stimulate human CMF to express additional proinflammatory cytokines. Furthermore, we hypothesized that these effects may be modulated by the anti-inflammatory cytokine interleukin-10 (IL-10). Human CMF were cultured from atrial biopsies from multiple patients. Interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and cardiotrophin-1 (CT-1) mRNA expression and secretion were measured using quantitative real-time RT-PCR and enzyme-linked immunosorbent assay. IL-1alpha (0.001-10 ng/ml, 0-6 h) stimulated IL-1beta, TNF-alpha, and IL-6 mRNA expression with distinct temporal and concentration profiles, resulting in increased cytokine secretion. The response to IL-1alpha was much greater than with TNF-alpha. Neither IL-1alpha nor TNF-alpha treatment modulated CT-1 mRNA expression. Immunoblotting with phosphospecific antibodies revealed that IL-1alpha stimulated the extracellular signal-regulated kinase (ERK)-1/2, p38 mitogen-activated protein kinase (MAPK), c-Jun NH(2)-terminal kinase (JNK), phosphatidylinositol 3-kinase (PI 3-kinase)/protein kinase B (Akt), and nuclear factor (NF)-kappaB signaling pathways. Pharmacological inhibitor studies indicated roles for PI 3-kinase/Akt and NF-kappaB pathways in mediating IL-1beta expression, and for NF-kappaB and p38 MAPK pathways in mediating TNF-alpha expression. IL-1alpha-induced IL-6 mRNA expression was reduced by p38 MAPK inhibition, but increased by ERK and JNK pathway inhibitors. IL-10 produced a consistent but modest reduction in IL-1alpha-induced IL-6 mRNA levels (not IL-1beta or TNF-alpha), but this was not reflected by reduced IL-6 protein secretion. In conclusion, IL-1alpha stimulates human CMF to express IL-1beta, TNF-alpha, and IL-6 via specific signaling pathways, responses that are unaffected by IL-10 exposure.

Receptor activator of NF-κB ligand induces the expression of carbonic anhydrase II, cathepsin K, and matrix metalloproteinase-9 in osteoclast precursor RAW264.7 cells

Interleukin-1 (IL-1) is a proinflammatory cytokine that is a potent stimulator of bone resorption and an inhibitor of bone formation, whereas macrophage colony-stimulating factor (M-CSF) and receptor activator of NF-kappaB (RANK) ligand (RANKL) are essential and sufficient for osteoclast differentiation. Recently, we showed that IL-1alpha affects mineralized nodule formation in vitro and halts bone matrix turnover. We also showed that IL-1alpha stimulates osteoclast formation via the interaction of RANKL with RANK by increasing M-CSF and prostaglandin E(2) and decreasing osteoprotegerin. Here, we examined the effects of IL-1alpha or RANKL and/or M-CSF in the presence of IL-1alpha on the expression of carbonic anhydrase II (CAII), cathepsin K, matrix metalloproteinase-9 (MMP-9), RANK, M-CSF receptor (c-fms), and c-fos transcription factor using RAW264.7 cells as osteoclast precursors. Cells were cultured for up to 14 days in 0 or 100 U/ml IL-1alpha and either 50 ng/ml RANKL, 10 ng/ml M-CSF, or 50 ng/ml RANKL+10 ng/ml M-CSF in the presence of 100 U/ml IL-1alpha. The formation of osteoclast-like cells was estimated using tartrate-resistant acid phosphatase staining. Expression of the genes coding for the six proteins of interest was determined using real-time PCR, and the expression of the three enzymes was examined using Western blotting or ELISA. In the presence of IL-1alpha, expression of CAII, cathepsin K, and MMP-9 was markedly increased in cells cultured with RANKL or M-CSF+RANKL, whereas expression was difficult to detect in cells cultured with IL-1alpha alone and M-CSF. RANK and c-fos expression was also increased in cells cultured with RANKL or M-CSF+RANKL in the presence of IL-1alpha, whereas c-fms expression did not change. These results indicate that the expression of CAII, cathepsin K, and MMP-9 in RAW264.7 cells is not induced by M-CSF, but by RANKL in the presence of IL-1alpha.

IL-17 and IL-22 mediate IL-20 subfamily cytokine production in cultured keratinocytes via increased IL-22 receptor expression

IL-20 cytokine subfamily members, including IL-19, IL-20, and IL-24, are highly expressed in psoriatic skin lesions. Here, we demonstrate that psoriasis mediators IL-17 and IL-22 synergistically induce the production of IL-20 subfamily proteins in cultured human keratinocytes. Interestingly, expression of the IL-22 receptor (IL-22R) also increased in epidermal lesions versus normal skin. IL-22R over-expression using an adenoviral vector to mimic psoriatic conditions in cultured keratinocytes significantly enhanced IL-17- and IL-22-induced production of IL-20 subfamily cytokines. Furthermore, IL-17 and IL-22 coordinately enhanced MIP-3alpha, IL-8, and heparin-binding EGF-like growth factor (HB-EGF) production, depending on the amount of IL-22R expression. Additionally, because IL-20 and IL-24 share the IL-22R with IL-22, the function of IL-20 and IL-24 was also increased. IL-20 and IL-24 have effects similar to that of IL-22; IL-24 showed more potent expression than IL-20. A combination of IL-24 and IL-17 increased the production of MIP-3alpha, IL-8, and HB-EGF, as did a combination of IL-22 and IL-17. These data indicate that increased IL-22R expression in epidermal keratinocytes contributes to the pathogenesis of psoriasis through enhancing the coordinated effects of IL-22 and IL-17, inducing the production of the IL-20 subfamily, chemokines, and growth factors.

Induction of indoleamine 2,3-dioxygenase by interferon-gamma in human islets

Indoleamine 2,3-dioxygenase (IDO) catalyzes the initial, rate-limiting step of tryptophan (Trp) catabolism along the kynurenine (KYN) pathway, and its induction in cells of the immune system in response to cytokines has been implicated in the regulation of antigen presentation and responses to cell-mediated immune attack. Microarray and quantitative PCR analyses of isolated human islets incubated with interferon (IFN)-gamma for 24 h revealed increased expression of IDO mRNA (>139-fold) and Trp-tRNA synthase (WARS) (>17-fold) along with 975 other transcripts more than threefold, notably the downstream effectors janus kinase (JAK)2, signal transducer and activator of transcription (STAT)1, IFN-gamma regulatory factor-1, and several chemokines (CXCL9/MIG, CXCL10/IP10, CXCL11/1-TAC, CCL2, and CCL5/RANTES) and their receptors. IDO protein expression was upregulated in IFN-gamma-treated islets and accompanied by increased intracellular IDO enzyme activity and the release of KYN into the media. The response to IFN-gamma was countered by interleukin-4 and 1alpha-methyl Trp. Immunohistochemical localization showed IDO to be induced in cells of both endocrine, including pancreatic duodenal homeobox 1-positive beta-cells, and nonendocrine origin. We postulate that in the short term, IDO activation may protect islets from cytotoxic damage, although chronic exposure to various Trp metabolites could equally lead to beta-cell attrition.

Mechanisms of murine lacrimal gland repair after experimentally induced inflammation

PURPOSE

The authors recently reported that a severe inflammatory response resulting in substantial loss of acinar cells was induced by a single injection of interleukin-1alpha into the lacrimal gland and that this effect was reversible. The purpose of the present study was to determine the mechanisms involved in lacrimal gland injury and repair.

METHODS

Inflammation was induced by direct injection of recombinant human interleukin-1alpha (IL-1alpha, 1 microg in 2 microL) into the exorbital lacrimal glands of anesthetized female BALB/c mice. Animals were killed 1, 2, 3, 4, 5, 6, or 7 days after injection. Exorbital lacrimal glands were then removed and processed for measurement of protein secretion, histology, immunohistochemistry, and Western blotting.

RESULTS

The results show that lacrimal gland acinar cells are lost through programmed cell death (apoptosis) and autophagy. They also show that the number of nestin (a stem cell marker)-positive cells increased 2 to 3 days after injury and that some of these cells were also positive for Ki67 (a cell proliferation marker) and alpha-smooth muscle actin (a marker of myoepithelial cells). Finally, they show that the amount of phosphorylated Smad1/5/8 (effector molecules of bone morphogenetic protein 7 [BMP7]) increased 2 to 3 days after injury and could also be detected in nestin-positive cells.

CONCLUSIONS

The lacrimal gland contains stem/progenitor cells capable of tissue repair after injury. Programmed cell death after injury triggers proliferation and differentiation of these cells, presumably through activation of the BMP7 pathway.

The anemia of inflammation/malignancy: mechanisms and management

Anemia is a common complication in patients with inflammatory diseases of many kinds, including cancer. The mechanisms that have captured the most attention include cytokine-mediated changes in both the production of and the response to erythropoietin (Epo), as well as important alterations in iron metabolism. The last is brought about by the relatively recently recognized peptide hormone, hepcidin. The availability of recombinant human Epo and its derivatives (known by class as Erythropoietic Stimulating Agents, ESAs) has dramatically changed anemia management in patients with cancer but, in the process, has raised as many issues as have been answered. This chapter reviews the mechanisms resulting in anemia in inflammation, including cancer, and focuses on the controversies around management with the ESAs and the adjuvant use of iron in anemia management.

Phospholipid composition of in vitro endothelial microparticles and their in vivo thrombogenic properties

INTRODUCTION

Microparticles from activated endothelial cells (EMP) are well known to expose tissue factor (TF) and initiate coagulation in vitro. TF coagulant activity is critically dependent on the presence of aminophospholipids, such as phosphatidylserine (PS) and phosphatidylethanolamine (PE), but it is unknown whether or not TF-exposing EMP are enriched in such aminophospholipids. Furthermore, despite the fact that EMP have been reported in several pathological conditions, direct evidence for their (putative) coagulant properties in vivo is still lacking. We investigated the phospholipid composition of endothelial MP (EMP) and their thrombogenic properties in vivo.

MATERIALS AND METHODS

Human umbilical vein endothelial cells (HUVEC; n=3) were incubated with or without interleukin (IL)-1alpha (5 ng/mL; 0-72 h). Phospholipid composition of EMP was determined by high-performance thin layer chromatography. The association between EMP, TF antigen and activity was confirmed in vitro (ELISA, Western blot and thrombin generation). Thrombogenic activity of EMP in vivo was determined in a rat venous stasis model.

RESULTS

Levels of TF antigen increased 3-fold in culture medium of IL-1alpha-treated cells (P<0.0001). This TF antigen was associated with EMP and appeared as a 45-47 kDa protein on Western blot. In addition, EMP from activated cells were enriched in both PS (P<0.0001) and PE (P<0.0001), and triggered TF-dependent thrombin formation in vitro and thrombus formation in vivo. In contrast, EMP from control cells neither initiated coagulation in vitro nor thrombus formation in vivo.

CONCLUSIONS

EMP from activated endothelial cells expose coagulant tissue factor and are enriched in its cofactors PS and PE.

Differential regulation of proteoglycan 4 metabolism in cartilage by IL-1alpha, IGF-I, and TGF-beta1

OBJECTIVES

To determine (1) if interleukin-1 alpha (IL-1alpha), insulin like growth factor I (IGF-I), and transforming growth factor-beta 1 (TGF-beta1) regulate proteoglycan 4 (PRG4) metabolism in articular cartilage, in terms of chondrocytes expressing PRG4 and PRG4 bound at the articular surface, and (2) if these features of cartilage PRG4 metabolism correlate with its secretion.

METHODS

Articular cartilage explants were harvested and cultured for 6 days with or without 10% fetal bovine serum (FBS), alone, or with the addition of 10ng/ml IL-1alpha, 300ng/ml IGF-I, or 10ng/ml TGF-beta1. PRG4 expression by chondrocytes in the cartilage disks was assessed by immunohistochemistry (IHC). PRG4 bound to the articular surface of disks was quantified by extraction and enzyme-linked immunosorbent assay (ELISA). PRG4 secreted into culture medium was quantified by ELISA and characterized by Western Blot.

RESULTS

PRG4 expression by chondrocytes near the articular surface was markedly decreased by IL-1alpha, stimulated by TGF-beta1, and not affected by IGF-I. The level of PRG4 accumulation in the culture medium was correlated with the number of chondrocytes expressing PRG4. The amount of PRG4 bound at the articular surface was modulated by incubation in medium including FBS, but did not correlate with levels of PRG4 secretion.

CONCLUSIONS

Cartilage secretion of PRG4 is highly regulated by certain cytokines and growth factors, in part through alteration of the number of PRG4-secreting chondrocytes near the articular surface. The biochemical milieu may regulate the PRG4 content of synovial fluid during cartilage injury or repair.

Interleukin-1alpha regulates antimicrobial peptide expression in human keratinocytes

Human epidermis and epithelium serve as physiologic barriers to protect against noxious and infectious agents. Contributing to the defense against infection, epithelial cells express antimicrobial peptides (AMPs). The expression of AMPs in keratinocytes is generally regulated directly by bacteria and indirectly by proinflammatory cytokines. Bacteria may also regulate AMP expression by inducing keratinocyte expression of the autonomous proinflammatory cytokine, interleukin-1alpha (IL-1alpha). To test the hypothesis that AMP expression may be regulated by cell autonomous cytokines, we investigated the effect of IL-1alpha on the expression of AMPs in human keratinocytes (HaCaT cells) by microarray, northern blot, reverse transcriptase (RT)-PCR and western blot analyses. IL-1alpha increased expression of mRNA in a dose- and time-dependent manner specific for lipocalin 2, S100A8, S100A9 and secretory leukocyte protease inhibitor (SLPI) more than twofold relative to nonstimulated cells (control), and slightly upregulated S100A7 and beta-defensin-2. Furthermore, the expression of lipocalin 2, S100A7, S100A8, S100A9 and SLPI proteins were upregulated by IL-1alpha. On the other hand, HaCaT cells expressed mRNA specific for other AMPs, including cystatin 3, adrenomedullin, RNase-7 and mucin 5, which were unaffected by IL-1alpha treatment. These results suggest that the autonomous keratinocyte cytokine, IL-1alpha, selectively upregulates the expression of AMPs which may modulate innate epithelial cell immunity in skin and mucosa.

Interleukin 1 alpha (IL1A) is a novel regulator of the blood-testis barrier in the rat

Throughout spermatogenesis, leptotene spermatocytes must traverse the blood-testis barrier (BTB) at stages VIII-XI to gain entry into the adluminal compartment for continued development. However, the mechanism underlying BTB restructuring remains somewhat elusive. In this study, interleukin 1 alpha (IL1A) was administered intratesticularly to adult rats in order to assess its effects on spermatogenesis. IL1A was shown to perturb Sertoli-germ cell adhesion, resulting in germ cell loss from approximately 50% of seminiferous tubules by 15 days posttreatment. Equally important, the functional integrity of the BTB was compromised when inulin-fluorescein isothiocyanate was detected in the adluminal compartment of the seminiferous epithelium following its administration via the jugular vein. Interestingly, IL1A did not affect the steady-state levels of proteins that confer BTB function, namely OCLN, CLDN1, F11R, TJP1, and CDH2. Instead, the localizations of OCLN, F11R, and TJP1 in the seminiferous epithelium were altered; these proteins appeared to move away from sites of cell-cell contact. Moreover, IL1A was shown to perturb the orderly arrangement of filamentous actin at the BTB and apical ectoplasmic specialization with distinct areas illustrating loss of actin filaments. Taken collectively, these results suggest that IL1A-induced BTB disruption is not mediated via the reduction of target protein levels. Instead, IL1A's primary cellular target appears to be the Sertoli cell actin cytoskeleton. It is possible that localized production of IL1A by Sertoli and/or germ cells in vivo results in BTB restructuring, and this may facilitate the movement of leptotene spermatocytes across the BTB.

Microvascular endothelial cells express a phosphatidylserine receptor: a functionally active receptor for phosphatidylserine-positive erythrocytes

Phosphatidylserine (PS)-positive erythrocytes adhere to endothelium and subendothelial matrix components. While thrombospondin mediates these inter-actions, it is unknown whether PS-associated erythrocyte-endothelial adhesion occurs in the absence of plasma ligands. Using ionophore-treated PS-expressing control HbAA erythrocytes, we demonstrate that PS-positive erythrocytes adhered to human lung microendothelial cells in the absence of plasma ligands, that this adhesion was enhanced following endothelial activation with IL-1alpha, TNF-alpha, LPS, hypoxia, and heme, and that this adhesive interaction was selective to erythrocyte PS. We next explored whether microendothelial cells express an adhesion receptor that recognizes cell surface-expressed PS (PSR) similar to that expressed on activated macrophages. We demonstrate constitutive expression of both PSR mRNA and protein that were up-regulated in a time-dependent manner following endothelial activation. While minimal PSR expression was noted on unstimulated cells, endothelial activation up-regulated PSR surface expression. In antibody-blocking studies, using PS-positive erythrocytes generated either artificially via ionophore treatment of control erythrocytes or from patients with sickle cell disease, we demonstrate that PSR was functional, supporting PS-mediated erythrocyte adhesion to activated endothelium. Our results demonstrate the existence of a novel functional adhesion receptor for PS on the microendothelium that is up-regulated by such pathologically relevant agonists as hypoxia, cytokines, and heme.

Synergism of TNF and IL-1 in the induction of matrix metalloproteinase-3 in trabecular meshwork

PURPOSE

TNF and IL-1 increase matrix metalloproteinase-3 (MMP-3) expression in the trabecular meshwork (TM). TNF-alpha, in combination with IL-1alpha or IL-1beta, produces highly synergistic MMP-3 increases. Possible mechanisms for this synergism in TM cells were investigated.

METHODS

Porcine and human TM cells were treated with TNF-alpha, IL-1alpha, IL-1beta and their combinations. Western immunoblots were used to evaluate MMP-3, MMP-9, MMP-12, TNF-alpha, IL-1alpha, IL-1beta, IL-6, TNF receptor I (RI), IL-1 RI, and IL-1 RII levels and the phosphorylation of Erk, JNK, and p38 MAP kinases. Dose-response effects for TNF-alpha, IL-1alpha and IL-1beta on MMP-3 were evaluated. Microarray and quantitative RT-PCR were used to determine mRNA levels. MMP-3 transcription rate was assessed by transfecting TM cells with an MMP-3 promoter/reporter construct. Combined cytokine effects on outflow facility were appraised in perfused anterior segment organ culture.

RESULTS

TNF-alpha, IL-1alpha, and IL-1beta each individually increased MMP-3 levels, whereas TNF-alpha in combination with IL-1alpha or IL-1beta produced highly synergistic increases. MMP-9 and MMP-12 levels were also elevated, but only MMP-12 showed synergism. IL-1alpha, IL-1beta, and IL-6, but not TNF-alpha mRNA or protein level, were elevated by these cytokines. Maximum MMP-3 production for individual cytokines, even at high doses, was far less than with dual cytokine doses. Erk 1 and 2, JNK 1 and 2, and p38 alpha and beta phosphorylation increased, but not synergistically. However, phosphorylation of novel isoforms of JNK and p38 delta and gamma did show synergism. MMP-3 mRNA levels and transcription rates also demonstrated synergism. TNF-alpha significantly increased IL-1 RI levels. Synergism in outflow facility was observed with TNF-alpha and IL-1alpha.

CONCLUSIONS

TNF-alpha, in combination with IL-1alpha or IL-1beta, produced intense synergistic increases in MMP-3 and MMP-12 but not in MMP-9. Induction of IL-1 RI by TNF-alpha partially explains the synergism. Responses of novel JNK and p38 MAP kinase delta and gamma isoforms also partially account for the synergism. Understanding this strong synergistic effect may provide useful insight into optimizing therapeutic regulation of intraocular pressure in glaucoma.

Modulatory effect of interleukin-1α on expression of structural matrix proteins, MMPs and TIMPs in human cardiac myofibroblasts: role of p38 MAP kinase

The proinflammatory cytokine interleukin-1 (IL-1) elicits catabolic effects on the myocardial extracellular matrix (ECM) early after myocardial infarction but there is little understanding of its direct effects on cardiac myofibroblasts (CMF), or the role of p38 mitogen-activated protein kinase (MAPK). We used a focused RT-PCR microarray to investigate the effects of IL-1α on expression of 41 ECM genes in CMF cultured from different patients, and explored regulation by p38 MAPK. IL-1α (10 ng/ml, 6h) had minimal effect on mRNA expression of structural ECM proteins, including collagens, laminins, fibronectin and vitronectin. However, it induced marked increases in expression of specific ECM proteases, including matrix metalloproteinases MMP-1 (collagenase-1), MMP-3 (stromelysin-1), MMP-9 (gelatinase-B) and MMP-10 (stromelysin-2). Conversely, IL-1α reduced mRNA and protein expression of ADAMTS1, a metalloproteinase that suppresses neovascularization. IL-1α increased expression of TIMP-1 slightly, but not TIMP-2. Data for MMP-1, MMP-2, MMP-3, MMP-9, MMP-10 and ADAMTS1 were confirmed by quantitative real-time RT-PCR. Tumor necrosis factor-alpha (TNFα), another important myocardial proinflammatory cytokine, did not alter expression of these metalloproteinases. IL-1α strongly activated the p38 MAPK pathway in human CMF. Pharmacological inhibitors of p38-α/β (SB203580) or p38-α/β/γ/δ (BIRB-0796) reduced MMP-3 and ADAMTS1 mRNA expression, but neither inhibitor affected MMP-9 levels. MMP-1 and MMP-10 expression were inhibited by BIRB-0796 but not SB203580, suggesting roles for p38-γ/δ. In summary, IL-1α induces a distinct pattern of ECM protein and protease expression in human CMF, in part regulated by distinct p38 MAPK subtypes, affirming the key role of IL-1α and CMF in post-infarction cardiac remodeling.

Imatinib mesylate (Gleevec®) enhances mature osteoclast apoptosis and suppresses osteoclast bone resorbing activity

Recent studies have reported that imatinib mesylate, a kinase inhibitor that targets the intracellular tyrosine kinase BCR-ABL and the platelet derived growth factor (PDGF) receptor, is an effective inhibitor of the macrophage colony stimulating factor (M-CSF) receptor, c-FMS. Given that M-CSF signalling through c-FMS plays an important role in osteoclast biology, we speculated that blocking such a pathway with imatinib may modulate osteoclast activity. Using a cell model of mature rabbit osteoclasts, we thus investigated the effect of imatinib on in vitro osteoclast apoptosis and bone resorbing activity. Our findings demonstrate that imatinib dose-dependently stimulates osteoclast apoptosis, a phenomenon which is blocked by the caspase I inhibitor Z-VAD-fmk. The ability of imatinib to enhance osteoclast cell death was accompanied by a dose-dependent inhibition of osteoclast bone resorbing activity. Imatinib was also found to inhibit M-CSF-induced osteoclast survival as well as M-CSF-induced osteoclast bone resorbing activity, but was without effect on interleukin 1alpha (IL-1alpha) and receptor activator of nuclear factor kappa B ligand (RANKL)-induced inhibition of osteoclasts apoptosis, further supporting the hypothesis that imatinib may affect mature osteoclasts through the inhibition of c-FMS. Taken together, these results suggest that imatinib could be of clinical value in treating diseases where bone destruction can occur due to excessive M-CSF production such as osteoporosis, inflammatory-and tumor-induced osteolysis.

IL-20 gene expression is induced by IL-1beta through mitogen-activated protein kinase and NF-kappaB-dependent mechanisms

IL-20 is a novel member of the IL-10 cytokine family with pleiotropic effects. Current knowledge of what triggers and regulates IL-20 gene expression is sparse. The aim of this study was to investigate the regulation of IL-20 expression in cultured normal human keratinocytes. The expression of IL-20 was rapidly induced by proinflammatory stimuli, in particular IL-1beta, IL-6, and UVB irradiation. Using kinase inhibitors and small-interfering RNA, we discovered that the p38 mitogen-activated protein kinase (MAPK) as well as inhibitory kappaB kinase-NF-kappaB signaling pathways are crucial for IL-20 expression. By electrophoretic mobility shift assay two kappaB-binding sites were identified upstream from the start codon in the IL-20 gene. Supershift analysis revealed binding of the p50/p65 heterodimer. Furthermore, the p38 MAPK was shown to exert its effects on IL-20 expression through activation of the downstream kinase mitogen- and stress-activated kinase 1 (MSK1), indicating transactivation of NF-kappaB driven IL-20 messenger RNA transcription as an important mechanism of action. IL-20 is assumed to be a key cytokine in the pathogenesis of psoriasis and possibly cancer, and therefore the p38 MAPK, MSK1, and NF-kappaB may be important new molecular targets for the modulation of IL-20 expression in these diseases.

Elevated expression levels of miR-143/5 in saphenous vein smooth muscle cells from patients with Type 2 diabetes drive persistent changes in phenotype and function

Type 2 diabetes (T2DM) promotes premature atherosclerosis and inferior prognosis after arterial reconstruction. Vascular smooth muscle cells (SMC) respond to patho/physiological stimuli, switching between quiescent contractile and activated synthetic phenotypes under the control of microRNAs (miRs) that regulate multiple genes critical to SMC plasticity. The importance of miRs to SMC function specifically in T2DM is unknown. This study was performed to evaluate phenotype and function in SMC cultured from non-diabetic and T2DM patients, to explore any aberrancies and investigate underlying mechanisms. Saphenous vein SMC cultured from T2DM patients (T2DM-SMC) exhibited increased spread cell area, disorganised cytoskeleton and impaired proliferation relative to cells from non-diabetic patients (ND-SMC), accompanied by a persistent, selective up-regulation of miR-143 and miR-145. Transfection of premiR-143/145 into ND-SMC induced morphological and functional characteristics similar to native T2DM-SMC; modulating miR-143/145 targets Kruppel-like factor 4, alpha smooth muscle actin and myosin VI. Conversely, transfection of antimiR-143/145 into T2DM-SMC conferred characteristics of the ND phenotype. Exposure of ND-SMC to transforming growth factor beta (TGFβ) induced a diabetes-like phenotype; elevated miR-143/145, increased cell area and reduced proliferation. Furthermore, these effects were dependent on miR-143/145. In conclusion, aberrant expression of miR-143/145 induces a distinct saphenous vein SMC phenotype that may contribute to vascular complications in patients with T2DM, and is potentially amenable to therapeutic manipulation.

Enhancing effect of IL-1alpha on neurogenesis from adult human mesenchymal stem cells: implication for inflammatory mediators in regenerative medicine

Mesenchymal stem cells (MSCs) are mesoderm-derived cells, primarily resident in adult bone marrow. MSCs show lineage specificity in generating specialized cells such as stroma, fat, and cartilage. MSCs express MHC class II and function as phagocytes and APCs. Despite these immune-enhancing properties, MSCs also exert veto functions and show evidence for allogeneic transplantation. These properties, combined with ease in isolation and expansion, demonstrate MSCs as attractive candidates for tissue repair across allogeneic barriers. MSCs have also been shown to transdifferentiate in neuronal cells. We have reported expression of the neurotransmitter gene, Tac1, in MSC-derived neuronal cells, with no evidence of translation unless cells were stimulated with IL-1alpha. This result led us to question the potential role of immune mediators in the field of stem cell therapy. Using Tac1 as an experimental model, IL-1alpha was used as a prototypical inflammatory mediator to study functions on MSC-derived neuronal cells. Undifferentiated MSCs and those induced to form neurons were studied for their response to IL-1alpha and other proinflammatory cytokines using production of the major Tac1 peptide, substance P (SP), as readout. Although IL-1alpha induced high production of SP, a similar effect was not observed for all tested cytokines. The induced SP was capable of reuptake via its high-affinity NK1R and was found to stabilize IL-1R mRNA. IL-1alpha also enhanced the rate of neurogenesis, based on expression of neuronal markers and cRNA microarray analyses. The results provide evidence that inflammatory mediators need to be considered when deciding the course of MSC transplantation.

Profile of MMP and TIMP Expression in Human Pancreatic Stellate Cells: Regulation by IL-1α and TGFβ and Implications for Migration of Pancreatic Cancer Cells

Pancreatic ductal adenocarcinoma is characterized by a prominent fibroinflammatory stroma with both tumor-promoting and tumor-suppressive functions. The pancreatic stellate cell (PSC) is the major cellular stromal component and the main producer of extracellular matrix proteins, including collagens, which are degraded by metalloproteinases (MMPs). PSCs interact with cancer cells through various factors, including transforming growth factor (TGF)β and interleukin (IL)-1α. The role of TGFβ in the dual nature of tumor stroma, i.e., protumorigenic or tumor suppressive, is not clear. We aimed to investigate the roles of TGFβ and IL-1α in the regulation of MMP profiles in PSCs and the subsequent effects on cancer cell migration. Human PSCs isolated from surgically resected specimens were cultured in the presence of pancreatic cancer cell lines, as well as IL-1α or TGFβ. MMP production and activities in PSCs were quantified by gene array transcripts, mRNA measurements, fluorescence resonance energy transfer-based activity assay, and zymography. PSC-conditioned media and pancreatic cancer cells were included in a collagen matrix cell migration model. We found that production of IL-1α by pancreatic cancer cells induced alterations in MMP and tissue inhibitors of matrix metalloproteinase (TIMP) profiles and activities in PSCs, upregulated expression and activation of MMP1 and MMP3, and enhanced migration of pancreatic cancer cells in the collagen matrix model. TGFβ counteracted the effects of IL-1α on PSCs, reestablished PSC MMP and TIMP profiles and activities, and inhibited migration of cancer cells. This suggests that tumor TGFβ has a role as a suppressor of stromal promotion of tumor progression through alterations in PSC MMP profiles with subsequent inhibition of pancreatic cancer cell migration.

Ozone exposure of macrophages induces an alveolar epithelial chemokine response through IL-1alpha

Ozone is known to produce an acute influx of neutrophils, and alveolar epithelial cells can secrete chemokines and modulate inflammatory processes. However, direct exposure of alveolar epithelial cells and macrophages to ozone (O(3)) produces little chemokine response. To determine if cell-cell interactions might be responsible, we investigated the effect of alveolar macrophage-conditioned media after ozone exposure (MO(3)CM) on alveolar epithelial cell chemokine production. Serum-free media were conditioned by exposing a rat alveolar macrophage cell line NR8383 to ozone for 1 hour. Ozone stimulated secretion of IL-1alpha, IL-1beta, and IL-18 from NR8383 cells, but there was no secretion of chemokines or TNF-alpha. Freshly isolated type II cells were cultured, so as to express the biological markers of type I cells, and these cells are referred to as type I-like cells. Type I-like cells were exposed to diluted MO(3)CM for 24 hours, and this conditioned medium stimulated secretion of cytokine-induced neutrophil chemattractant-1 (CXCL1) and monocyte chemoattractant protein-1 (CCL2). Secretion of these chemokines was inhibited by the IL-1 receptor antagonist. Although both recombinant IL-1alpha and IL-1beta stimulated alveolar epithelial cells to secrete chemokines, recombinant IL-1alpha was 100-fold more potent than IL-1beta. Furthermore, neutralizing anti-rat IL-1alpha antibodies inhibited the secretion of chemokines by alveolar epithelial cells, whereas neutralizing anti-rat IL-1beta antibodies had no effect. These observations indicate that secretion of IL-1alpha from macrophages stimulates alveolar epithelial cells to secrete chemokines that can elicit an inflammatory response.

Interleukin 1alpha-induced NFkappaB activation and chemokine mRNA stabilization diverge at IRAK1

Interleukin 1alpha (IL-1alpha) is capable of driving pro-inflammatory gene expression through both the initiation of transcription and by prolonging the half-life of short-lived mRNAs. Although the signaling events linking the IL-1 receptor to the activation of NFkappaB and the initiation of transcription have been well characterized, less is known about the signaling events linking to mRNA stabilization. As a model to study the control of mRNA stability we have used the mouse chemokine KC, expression of which requires both NFkappaB-driven transcription and stabilization of the constitutively unstable mRNA. We have evaluated the role of signaling adaptors known to play a role in IL-1alpha-driven NFkappaB activation in the generation of mRNA stability. Surprisingly, although TRAF6 is essential for NFkappaB activation, it is not required for IL-1alpha-induced mRNA stabilization. IRAK1, which is recognized to function upstream of TRAF6, is required for both mRNA stabilization and activation of NFkappaB. Consistent with the previous findings, the TRAF6 interaction sites in IRAK1 are required for NFkappaB activation but do not play a role in mRNA stabilization. These findings indicate that signals from the IL-1 receptor segregate into at least two separate pathways at the level of IRAK1; one couples through TRAF6 to NFkappaB activation while a second utilizes a TRAF6-independent pathway that is responsible for mRNA stabilization.