Activated Endothelial Cells Induce Apoptosis in Leukemic Cells by Endothelial Interleukin-8

Amorphous-Crystalline Calcium Phosphate Coating Promotes In Vitro Growth of Tumor-Derived Jurkat T Cells Activated by Anti-CD2/CD3/CD28 Antibodies

A modern trend in traumatology, orthopedics, and implantology is the development of materials and coatings with an amorphous-crystalline structure that exhibits excellent biocopatibility. The structure and physico-chemical and biological properties of calcium phosphate (CaP) coatings deposited on Ti plates using the micro-arc oxidation (MAO) method under different voltages (200, 250, and 300 V) were studied. Amorphous, nanocrystalline, and microcrystalline statesof CaHPO4 and β-Ca2P2O7 were observed in the coatings using TEM and XRD. The increase in MAO voltage resulted in augmentation of the surface roughness Ra from 2.5 to 6.5 µm, mass from 10 to 25 mg, thickness from 50 to 105 µm, and Ca/P ratio from 0.3 to 0.6. The electrical potential (EP) of the CaP coatings changed from -456 to -535 mV, while the zeta potential (ZP) decreased from -53 to -40 mV following an increase in the values of the MAO voltage. Numerous correlations of physical and chemical indices of CaP coatings were estimated. A decrease in the ZP magnitudes of CaP coatings deposited at 200-250 V was strongly associated with elevated hTERT expression in tumor-derived Jurkat T cells preliminarily activated with anti-CD2/CD3/CD28 antibodies and then contacted in vitro with CaP-coated samples for 14 days. In turn, in vitro survival of CD4+ subsets was enhanced, with proinflammatory cytokine secretion of activated Jurkat T cells. Thus, the applied MAO voltage allowed the regulation of the physicochemical properties of amorphous-crystalline CaP-coatings on Ti substrates to a certain extent. This method may be used as a technological mechanism to trigger the behavior of cells through contact with micro-arc CaP coatings. The possible role of negative ZP and Ca2+ as effectors of the biological effects of amorphous-crystalline CaP coatings is discussed. Micro-arc CaP coatings should be carefully tested to determine their suitability for use in patients with chronic lymphoid malignancies.

Endothelial IL-8 induced by porcine circovirus type 2 affects dendritic cell maturation and antigen-presenting function

Background

Porcine circovirus (PCV) disease caused by PCV type 2 (PCV2) is mainly attributed to immunosuppression and immune damage. PCV2 can infect vascular endothelial cells and induce high expression of endothelial IL-8. Dendritic cells (DCs), as professional antigen-presenting cells, can not only present antigens but also activate naïve T-cells, causing an immune response.

Methods

To demonstrate whether endothelial IL-8 is the main factor inhibiting the maturation and related functions of dendritic cells during PCV2 infection, monocyte-derived DCs (MoDCs) and porcine iliac artery endothelial cells (PIECs) processed by different methods were co-cultured in two ways. Flow cytometry, molecular probe labeling, fluorescence quantitative PCR, and the MTS assay were used to detect the changes in related functions and molecules of MoDCs.

Results

Compared to those in the PIEC-DC group, the endothelial IL-8 upregulation co-culture group showed significantly lower double-positive rates for CD80/86 and MHC-II of MoDCs and significantly increased endocytosis of MoDCs. Meanwhile, the adhesion rate and average fluorescence intensity of MoDCs were significantly downregulated in migration and adhesion experiments. Furthermore, the MHC-I and LAMP7 mRNA levels in MoDCs and the proliferation of MoDC-stimulated T-cells were markedly reduced. However, the changes in MoDCs of the endothelial IL-8 downregulation co-culture group were the opposite.

Conclusions

PCV2-induced endothelial IL-8 reduces the adhesion and migration ability of MoDCs, resulting in a decreased maturation rate of MoDCs, and further inhibits antigen presentation by DCs. These results may explain the immunosuppressive mechanism of PCV2 from the perspective of the interaction between endothelial cells and DCs in vitro.

Rough Titanium Oxide Coating Prepared by Micro-Arc Oxidation Causes Down-Regulation of hTERT Expression, Molecular Presentation, and Cytokine Secretion in Tumor Jurkat T Cells

The response of the human Jurkat T cell leukemia-derived cell line (Jurkat T cells) after 24 h of in vitro exposure to a titanium substrate (12 × 12 × 1 mm³) with a bilateral rough (R_a = 2.2–3.7 μm) titanium oxide coating (rTOC) applied using the micro-arc method in a 20% orthophosphoric acid solution was studied. A 1.5-fold down-regulation of hTERT mRNA expression and decreases in CD3, CD4, CD8, and CD95 presentation and IL-4 and TNFα secretion were observed. Jurkat T cell inactivation was not correlated with the generation of intracellular reactive oxygen species (ROS) and was not mediated by TiO₂ nanoparticles with a diameter of 14 ± 8 nm at doses of 1 mg/L or 10 mg/L. The inhibitory effect of the rTOC (R_a = 2.2–3.7 μm) on the survival of Jurkat T cells (Spearman’s coefficient r_s = −0.95; n = 9; p < 0.0001) was demonstrated by an increase in the necrotic cell count among the cell population. In turn, an elevation of the Ra index of the rTOC was accompanied by a linear increase (r = 0.6; p < 0.000001, n = 60) in the magnitude of the negative electrostatic potential of the titanium oxide surface. Thus, the roughness of the rTOC induces an electrostatic potential and decreases the viability of the immortalized Jurkat T cells through mechanisms unrelated to ROS generation. This may be useful for replacement surgery applications of rough TiO₂ implants in cancer patients.

Imbalance of morphofunctional responses of Jurkat T lymphoblasts at short-term culturing with relief zinc- or copper-containing calcium phosphate coating on titanium

Morphofunctional response of Jurkat T cells that were cultured for 24 h on substrates prepared from commercially pure titanium with relief microarc bilateral calcium phosphate coating containing copper or zinc was studied. Changes in the concentration of essential trace elements contained in this coating can cause significant imbalance of molecular processes of differentiation, secretion, apoptosis, and necrosis and reduce tumor cell survival.

Anti-cancer, anti-inflammatory and anti-microbial activities of plant extracts used against hematological tumors in traditional medicine of Jordan

ETHNOPHARMACOLOGICAL RELEVANCE

Mercurialis annua L., Bongardia chrysogonum L., and Viscum cruciatum Sieb have been traditionally used by local herbalists in Jordan for the treatment of hematopoietic neoplasms.

AIM OF THE STUDY

To determine the anti-cancer, anti-inflammatory and anti-microbial potentials of the three extracts against two of the most common hematopoietic malignancies in the Jordanian populations; Burkitt's lymphoma and Multiple myeloma.

MATERIALS AND METHODS

The anti-cancer activity was tested against the two cell lines (BJAB Burkitt's lymphoma and U266 multiple myeloma) using the MTT and trypan blue assays. The agar dilution assay was used to study the anti-microbial activity against Gram-positive bacteria, Gram-negative bacteria, anaerobic bacteria and yeast. The pro-inflammatory cytokines interleukin (IL) -1β, IL-8 and tumor necrosis factor-α (TNF-α) were measured in the pretreated cell lines using ELISA assay to determine the anti-inflammatory activity of Viscum cruciatum Sieb against the two cell lines.

RESULTS

The results show no evidence of stimulation of tumor growth by any of the three extracts comprising cell lines from hematological malignancies, but Viscum cruciatum Sieb showed a selective anticancer activity against BJAB cells, with IC(50) value of 14.21μg/ml. The antimicrobial effect was only noticed with Viscum cruciatum extract by inhibiting Staphylococcus aureus, Candida albicans and Propionibacterium acne, but not Pseudomonas aeruginosa at MIC of 1.25, 1.25, 0.625 and <5mg/ml, respectively. The highest activity was against the anaerobic bacteria Propionibacterium acne. Viscum cruciatum Sieb extract showed an inhibitory effect on the pro-inflammatory cytokine IL-8, but it increased TNF-α and IL-1β secretions in BJAB cells. Whereas, it had an inhibitory effect on TNF-α and IL-1β cytokines while it enhanced IL-8 secretions in U266 cells.

CONCLUSION

Among the three tested herbal extracts used in the traditional medicine in Jordan, only Viscum cruciatum Sieb showed high anti-cancer and anti-microbial potentials. They also had an anti-inflammatory effect. These observations raise the prospects of using Viscum cruciatum Sieb for treatment of diseases associated with some bacterial and fungal infections, for imbalanced cytokine production and for enhancing cancer and other immunotherapies.

Circulating IL-6 mediates lung injury via CXCL1 production after acute kidney injury in mice

Serum IL-6 is increased in patients with acute kidney injury (AKI) and is associated with prolonged mechanical ventilation and increased mortality. Inhibition of IL-6 in mice with AKI reduces lung injury associated with a reduction in the chemokine CXCL1 and lung neutrophils. Whether circulating IL-6 or locally produced lung IL-6 mediates lung injury after AKI is unknown. We hypothesized that circulating IL-6 mediates lung injury after AKI by increasing lung endothelial CXCL1 production and subsequent neutrophil infiltration. To test the role of circulating IL-6 in AKI-mediated lung injury, recombinant murine IL-6 was administered to IL-6-deficient mice. To test the role of CXCL1 in AKI-mediated lung injury, CXCL1 was inhibited by use of CXCR2-deficient mice and anti-CXCL1 antibodies in mice with ischemic AKI or bilateral nephrectomy. Injection of recombinant IL-6 to IL-6-deficient mice with AKI increased lung CXCL1 and lung neutrophils. Lung endothelial CXCL1 was increased after AKI. CXCR2-deficient and CXCL1 antibody-treated mice with ischemic AKI or bilateral nephrectomy had reduced lung neutrophil content. In summary, we demonstrate for the first time that circulating IL-6 is a mediator of lung inflammation and injury after AKI. Since serum IL-6 is increased in patients with either AKI or acute lung injury and predicts prolonged mechanical ventilation and increased mortality in both conditions, our data suggest that serum IL-6 is not simply a biomarker of poor outcomes but a pathogenic mediator of lung injury.

Recent advances in underlying pathologies provide insight into interleukin-8 expression-mediated inflammation and angiogenesis

Interleukin-8 has long been recognized to have anti-inflammatory activity, which has been established in various models of infection, inflammation, and cancer. Several cell types express the receptor for the cytokine IL-8 and upon its recognition produce molecules that are active both locally and systemically. Many different types of cells, in particular monocytes, neutrophils, epithelial, fibroblast, endothelial, mesothelial, and tumor cells, secrete IL-8. Increased expression of IL-8 and/or its receptors has been characterized in many chronic inflammatory conditions, including psoriasis, ARDS, COPD, and RA as well as many cancers, and its upregulation often correlates with disease activity. IL-8 constitutes the CXC class of chemokines, a potent chemoattractant and activator of neutrophils and other immune cells. It is a proangiogenic cytokine that is overexpressed in many human cancers. Therefore, inhibiting the effects of IL-8 signaling may be a significant therapeutic intervention.

Glycogen synthase kinase--3β inhibitors suppress leukemia cell growth

OBJECTIVE

The objective of this study was to investigate the effect of small molecule inhibitors of glycogen synthase kinase-3β (GSK-3β) on leukemia cell growth and survival.

MATERIALS AND METHODS

Analysis of cytotoxicity and cell proliferation was conducted using the MTS assay, cell-cycle analysis, and division tracking. Apoptosis was investigated by Annexin-V/7-aminoactinomycin D and caspase-3 expression. The effect of GSK-3β inhibitors was also tested in vivo in an animal model of leukemia. Gene expression analysis was performed to identify the genes modulated by GSK-3β inhibition in leukemia cells.

RESULTS

GSK-3β inhibitors suppress cell growth and induce apoptosis in seven leukemia cell lines of diverse origin, four acute myeloid leukemia, one myelodysplastic syndrome, and one acute lymphoblastic leukemia samples. GSK-3β inhibitors are cytotoxic for rapidly dividing clonogenic leukemia blasts, and higher doses of the inhibitors are needed to eliminate primitive leukemia progenitor/stem cells. Slow cell-division rate, low drug uptake, and interaction with bone marrow stroma make leukemia cells more resistant to apoptosis induced by GSK-3β inhibitors. Global gene expression analysis combined with functional approaches identified multiple genes and specific signaling pathways modulated by GSK-3β inhibition. An important role for Bcl2 in the regulation of apoptosis induced by GSK-3β inhibitors was defined by expression analysis and confirmed by using pharmacological inhibitors of the protein. In vivo administration of GSK-3β inhibitors delayed tumor formation in a mouse leukemia model. GSK-3β inhibitors did not affect hematopoietic recovery following irradiation.

CONCLUSIONS

Our data support further evaluation of GSK-3β inhibitors as promising novel agents for therapeutic intervention in leukemia and warrant clinical investigation in leukemia patients.

Developmental changes in circulating IL-8/CXCL8 isoforms in neonates

Interleukin-8 (IL-8/CXCL8) is widely expressed in fetal tissues although inflammatory changes are not seen. Circulating IL-8 is comprised of an endothelial-derived [ala-IL-8](77) isoform and another, more potent [ser-IL-8](72) secreted by most other cells; [ala-IL-8](77) can be converted into [ser-IL-8](72) by proteolytic removal of an N-terminal pentapeptide from [ala-IL-8](77). In this study, we show [ala-IL-8](77) is the predominant circulating isoform of IL-8 in premature neonates but not in term neonates/adults, who have [ser-IL-8](72) as the major isoform. This isoform switch from the less potent [ala-IL-8](77) to [ser-IL-8](72) correlates with a maturational increase in the neutrophil chemotactic potency of plasma IL-8. The emergence of [ser-IL-8](72) as the major isoform is likely due to increased plasma [ala-IL-8](77)-convertase activity and/or changes in the cellular sources of IL-8. Developmental changes in IL-8 isoforms may serve to minimize its inflammatory effects in the fetus and also provide a mechanism to restore its full activity after birth.

Continuous treatment of bestatin induces anti-angiogenic property in endothelial cells

CD13/aminopeptidase-N (CD13/APN) is an important regulator of angiogenesis where its expression on activated blood vessels is induced by angiogenic signals. A previous study demonstrated that angiogenesis is suppressed under the presence of high concentrations of aminopeptidase antagonists. However, the mechanisms underlying the inhibition of morphogenesis by aminopeptidase antagonists have not been elucidated. In this study, we have for the first time examined the effects of continuous treatment of therapeutic dose of aminopeptidase antagonists on vascular endothelial capillary-like tube formation. In the antagonists tested, only bestatin significantly interfered in the capillary tube formation of primary endothelial cells (EC) after treatment for 72 h. Aminopeptidase analysis revealed that inhibitory activity of bestatin was not specific for CD13/APN, and the other inhibitors lacking anti-angiogenic properties also inhibit cell-surface aminopeptidase activity as well or more potently than bestatin, suggesting that the angiogenesis-inhibitory effect of bestatin was not due to inhibition of CD13/APN activity at this concentration. To elucidate the influence of continuous treatment of bestatin on endothelial cells, we performed microarray analysis and revealed that 72-h treatment of a pharmacokinetic dose of bestatin modulated the several angiogenesis-related genes including vascular endothelial growth factor (VEGF). Northern blot analysis indicated that modulation of the VEGF gene became obvious after 48 h of treatment. Furthermore, knockdown of the VEGF gene by siRNA remarkably suppressed capillary tube formation and required a higher concentration of exogenous VEGF to reverse the capillary formation ability. These data suggested that bestatin decreases a reactivity of EC to angiogenesis stimuli, and it can be achieved by the regulation of angiogenesis-related gene expression.

Changes in gene expression profiles in response to selenium supplementation among individuals with arsenic-induced pre-malignant skin lesions

The molecular basis and downstream targets of oral selenium supplementation in individuals with elevated risk of cancer due to chronic exposure from environmental carcinogens has been largely unexplored. In this study, we investigated genome-wide differential gene expression in peripheral blood mononuclear cells (PBMC) from individuals with pre-malignant arsenic (As)-induced skin lesions before and after 6 months daily oral supplementation of 200 microg L-selenomethionine. The Affymetrix GeneChip Human 133A 2.0 array, containing probes for 22,277 gene transcripts, was used to assess gene expression. Three different normalization methods, RMA (robust multi-chip analysis), GC-RMA and PLIER (Probe logarithmic intensity error), were applied to explore differentially expressed genes. We identified a list of 28 biologically meaningful, significantly differentially expressed genes. Genes up-regulated by selenium supplementation included TNF, IL1B, IL8, SOD2, CXCL2 and several other immunological and oxidative stress-related genes. When mapped to a biological association network, many of the differentially expressed genes were found to regulate functional classes such as fibroblast growth factor, collagenase, matrix metalloproteinase and stromelysin-1, and thus, considered to affect cellular processes like apoptosis, proliferation and others. Many of the significantly up-regulated genes following selenium-supplementation were previously found by us to be down-regulated in a different set of individuals with As-induced skin lesions compared to those without. In conclusion, findings from this study may elucidate the biological effect of selenium supplementation in humans. Additionally, this study suggests that long-term selenium supplementation may revert some of the gene expression changes presumably induced by chronic As exposure in individuals with pre-malignant skin lesions.

Stimulation of endothelial IL-8 (eIL-8) production and apoptosis by phenolic metabolites of benzene in HL-60 cells and human bone marrow endothelial cells

Benzene toxicity is considered to be elicited by its metabolites and phenolic metabolites of benzene are known to induce apoptosis in leukemia cells in culture and in human bone marrow progenitor cells. One potential mechanism of apoptosis induced by benzene metabolites that has not been examined is the production of pro-apoptotic cytokines such as endothelial IL-8 from endothelial cells in bone marrow stroma. In this study, we utilized HL-60 cells which are known to produce the endothelial form of IL-8 (elL-8) and human bone marrow endothelial cells (HBMEC) as model systems. Hydroquinone (HQ), Catechol (Cat) and benzenetriol (BT) all induced eIL-8 production and apoptosis in HL-60 cells. HQ induced a marked 50-70-fold stimulation of eIL-8 levels and HL-60 cells were shown to have the eIL-8 receptor, CXCR I thus enabling an autocrine pathway of apoptosis. However, treatment with recombinant elL-8 failed to induce apoptosis in HL-60 cells as previously reported and antibodies to either IL-8 or CXCRI did not significantly abrogate benzene metabolite-induced apoptosis. HQ and Cat but not BT also induced stimulation of elL-8 production in HBMEC. These data demonstrate that although metabolites of benzene induce marked stimulation of eIL-8, this is unlikely to be responsible for apoptosis induced in HL-60 cells. Our data also demonstrates that phenolic metabolites of benzene stimulate the production of eIL-8 from HBMEC suggesting that higher levels of endothelial-derived cytokines may occur in bone marrow after benzene exposure.

Stimulation of endothelial IL-8 (eIL-8) production and apoptosis by phenolic metabolites of benzene in HL-60 cells and human bone marrow endothelial cells

Benzene toxicity is considered to be elicited by its metabolites and phenolic metabolites of benzene are known to induce apoptosis in leukemia cells in culture and in human bone marrow progenitor cells. One potential mechanism of apoptosis induced by benzene metabolites that has not been examined is the production of pro-apoptotic cytokines such as endothelial IL-8 from endothelial cells in bone marrow stroma. In this study, we utilized HL-60 cells which are known to produce the endothelial form of IL-8 (eIL-8) and human bone marrow endothelial cells (HBMEC) as model systems. Hydroquinone (HQ), Catechol (Cat) and benzenetriol (BT) all induced eIL-8 production and apoptosis in HL-60 cells. HQ induced a marked 50-70 fold stimulation of eIL-8 levels and HL-60 cells were shown to have the eIL-8 receptor, CXCR1 thus enabling an autocrine pathway of apoptosis. However, treatment with recombinant eIL-8 failed to induce apoptosis in HL-60 cells as previously reported and antibodies to either IL-8 or CXCR1 did not significantly abrogate benzene metabolite-induced apoptosis. HQ and Cat but not BT also induced stimulation of eIL-8 production in HBMEC. These data demonstrate that although metabolites of benzene induce marked stimulation of eIL-8, this is unlikely to be responsible for apoptosis induced in HL-60 cells. Our data also demonstrates that phenolic metabolites of benzene stimulate the production of eIL-8 from HBMEC suggesting that higher levels of endothelial-derived cytokines may occur in bone marrow after benzene exposure.

The chemokine receptor CCR8 mediates rescue from dexamethasone-induced apoptosis via an ERK-dependent pathway

Several chemokines have been shown to regulate cellular apoptosis following discrete stimuli. It was previously demonstrated that the CC chemokine CCL1 (I-309) rescues thymic lymphoma cells from apoptosis by unknown mechanisms. The aim of our study was to characterize the role of the CC chemokine receptor 8 (CCR8), the only described receptor for CCL1, in the rescue of murine thymic lymphoma cells and murine thymocytes from dexamethasone (dex)-induced apoptosis. We show here that the CCR8-restricted agonist Kaposi sarcoma-associated herpesvirus-encoded chemokine viral macrophage-inflammatory protein-1 (vMIP-1) rescues thymic lymphoma cells from dex-induced apoptosis, similar to CCL1, and that such rescue is extracellular-regulated kinase-dependent. Although it has been hypothesized that the rescuing effect of CCL1 from apoptosis could be CCR8-mediated, here, we formally demonstrate the role of such receptor as its selective antagonist encoded by the MC148 gene of molluscum contagiosum virus MC148/vMCC-I inhibits v-MIP-1- and CCL1-induced rescue activity. In addition, CCR8 ligands inhibit dex-induced apoptosis of murine thymocytes with potential implications for thymic selection.

IL-8 expression and its possible relationship with estrogen-receptor-negative status of breast cancer cells

Estrogen-receptor (ER) status is an important parameter in breast cancer management as ER-positive breast cancers have a better prognosis than ER-negative tumors. This difference comes essentially from the lower aggressiveness and invasiveness of ER-positive tumors. Here, we demonstrate, that interleukin-8 (IL-8) was clearly overexpressed in most ER-negative breast, ovary cell lines and breast tumor samples tested, whereas no significant IL-8 level could be detected in ER-positive breast or ovarian cell lines. We have also cloned human IL-8 from ER-negative MDA-MB-231 cells, and we show that IL-8 produced by breast cancer cells is identical to monocyte-derived IL-8. Interestingly, the invasion potential of ER-negative breast cancer cells is associated at least in part with expression of IL-8, but not with IL-8 receptor levels. Moreover, IL-8 increases the invasiveness of ER-positive breast cancer cells by two fold, thus confirming the invasion-promoting role of IL-8. On the other hand, exogenous expression of estrogen receptors in ER-negative cells led to a decrease of IL-8 levels. In summary, our data show that IL-8 expression is negatively linked to ER status of breast and ovarian cancer cells. We also support the idea that IL-8 expression is associated with a higher invasiveness potential of cancer cells in vitro, which suggests that IL-8 could be a novel marker of tumor aggressiveness.

Growth-related oncogene alpha induction of apoptosis in osteoarthritis chondrocytes

OBJECTIVE

To evaluate the apoptotic effect of the chemokine growth-related oncogene alpha (GROalpha), which we recently reported to be up-regulated in osteoarthritis (OA) chondrocytes. Chondrocyte apoptosis is considered to be a major determinant of cartilage damage in OA, a disease resulting from the aberrant production of inflammatory mediators (cytokines and chemokines) and effectors (matrix metalloproteinases and reactive oxygen and nitrogen species) by chondrocytes.

METHODS

We investigated the apoptotic effect of GROalpha on isolated human cells and on in vitro-cultured cartilage explants by conventional methods (morphology, detection of DNA fragmentation in situ and in solution, exposure of phosphatidylserine) and by analysis of "early" biochemical events (plasma membrane depolarization, activation of caspase 3, and phosphorylation of c-Jun N-terminal kinase/stress-activated protein kinase).

RESULTS

We clearly demonstrated that GROalpha was able to initiate a series of morphologic, biochemical, and molecular changes that led to chondrocyte apoptosis. Moreover, we found that additional signals delivered from the extracellular matrix (ECM) were essential in the control of chondrocyte susceptibility to GROalpha-induced apoptosis, since cell death was detected only when cells were stimulated after reestablishment of their proper interactions with the ECM, or in cartilage explant samples with reduced ECM, as indicated by decreased Safranin O staining.

CONCLUSION

GROalpha can induce apoptosis in articular chondrocytes, and the induction is dependent upon additional signals from the ECM. These findings are relevant to understanding the pathogenesis of OA, in view of the availability of the GROalpha chemokine in the joint space in the course of this rheumatic disease.

A monoclonal antibody and an enzyme immunoassay for human Ala-IL-8(77)

Interleukin-8 (IL-8) plays a central role in neutrophil chemotaxis and exerts a wide range of effects on various cells, ranging from tumor angiogenesis to impairment of neuronal signaling. Two main forms of IL-8 exist, one containing 77 amino acids (Ala-IL-8(77)) and a second containing 72 amino acids (Ser-IL-8(72)), which comprise more than 90% of IL-8 protein in cell cultures. IL-8(77) was reported to be produced predominantly by endothelial cells and is known as "endothelial" IL-8. IL-8(72) predominates in monocyte cultures and is known as "leukocyte" IL-8. While both forms have equal chemotactic activity in vivo, recent data suggest that their biological activities might be different. Here we describe the generation of a mouse monoclonal antibody (mAb) specific for IL-8(77) and the development of a corresponding immunoassay. Various immunization protocols were investigated. Immunization with conjugates of a peptide from the N-terminus of IL-8(77) (NTP(77)) resulted in the production of an IgG1 mAb (N11) that recognizes human IL-8(77) and neutralizes its chemotactic activity. A sensitive ELISA specific for IL-8(77) was developed using N11 for capture and a biotinylated mAb to IL-8(72) for detection. Using this immunoassay it was shown that the only form of IL-8 secreted in cell culture was IL-8(77) and that the IL-8(72) present was the result of proteolysis of IL-8(77). IL-8(77) was detected in plasma and cerebrospinal fluid (CSF) from patients with sepsis and meningitis.

New vessel formation and aberrant VEGF/VEGFR signaling in acute leukemia: does it matter?

Although many patients with acute leukemia achieve a hematological complete remission with aggressive intensive therapy protocols, a large proportion shows reoccurrence of disease. Novel strategies are warranted. In acute leukemia new vessel formation is observed. New vessel formation is the result of angiogenesis and vasculogenesis. The degree of neovascularization in the bone marrow is correlated with vascular endothelial growth factor (VEGF) expression in the leukemic cells. The present review discusses the impact of new vessel formation related to acute leukemia, the relation with various angiogenic factors and will focus on VEGF/VEGF receptor signaling.

Human gingival fibroblasts rescue butyric acid-induced T-cell apoptosis

We previously demonstrated that butyric acid, an extracellular metabolite from periodontopathic bacteria, induces cytotoxicity and apoptosis in murine thymocytes, splenic T cells, and human Jurkat T cells. In this study, we used a cell-to-cell interaction system to examine the contribution of gingival fibroblasts to the regulation of T-cell death induced by butyric acid. Butyric acid slightly suppressed fibroblast viability in a concentration-dependent fashion. However, DNA fragmentation assays indicated that butyric acid did not induce apoptosis for up to 21 h in human gingival fibroblasts (Gin 1, F41-G, and H. pulp cells). The culture supernatants were assayed for interleukin 1alpha (IL-1alpha), IL-1beta, IL-6, IL-8, IL-11, tumor necrosis factor alpha, and transforming growth factor beta, but only the IL-6, IL-8, and IL-11 levels were significantly increased by addition of butyric acid. Butyric acid- or Fas-induced Jurkat-cell apoptosis was attenuated when Jurkat cells were cocultured with either F41-G or Gin 1 cells that had been preincubated for 6 h with butyric acid. IL-8 slightly stimulated butyric acid- or Fas-induced Jurkat-cell apoptosis in a dose-dependent manner, although a low dose of IL-8 had a mildly inhibitory effect on apoptosis. In contrast, IL-6 and IL-11 significantly suppressed butyric acid- or Fas-induced apoptosis in a dose-dependent fashion. Furthermore, the addition of monoclonal antibodies against human IL-6 and IL-11 to cocultures of gingival fibroblasts and Jurkat cells partially eliminated T-cell recovery. These results suggest that the proinflammatory cytokines such as IL-6 and IL-11, produced in fibroblasts stimulated with butyric acid, are involved in the attenuation of T-cell apoptosis by gingival fibroblasts.

Orphan G protein-coupled receptor, GPR41, induces apoptosis via a p53/Bax pathway during ischemic hypoxia and reoxygenation

Orphan receptors that couple to G protein without known ligands are considered to relate directly to drug discovery. Here, we examine the expression of various orphan receptors in H9c2 cells during ischemic hypoxia and reoxygenation. Among orphan receptors examined, the level of G protein-coupled receptor 41 (GPR41) mRNA increases significantly, with a peak at 2 h after reoxygenation, and recovers to the control level by 3 h after reoxygenation. The level of glyceraldehyde-3-phosphate dehydrogenase mRNA used as an internal control remains almost constant. The levels of c-fos and c-jun mRNA increase significantly with ischemic hypoxia and reoxygenation. The transfection of GPR41 into H9c2 cells results in a significant decrease in cell number, with DNA fragmentation observed by in vitro and in situ assay. The amount of p53 protein increases significantly in the nuclei of cells expressing GPR41, accompanying an increase in the transcriptional activity of p53. Consistent with the activation of p53, the level of bax mRNA is significantly increased, which leads to an increase in Bax protein. Furthermore, the expression of a deletion mutant of a GPR41, which lacks the G protein binding site and shows an attenuation of intracellular phosphorylation signals to H9c2 cells, inhibits cell death and the increase in p53 protein within 24 h after reoxygenation. These observations demonstrate that GPR41 is a novel receptor that activates p53 leading to apoptosis during reoxygenation after ischemic hypoxia in H9c2 cells. We have designated GPR41 as the hypoxia-induced apoptosis receptor, HIA-R.

The Pathogenetic Role of Apoptosis in Hypercoagulable States

Hypercoagulable states are common disorders with high risk of thrombosis associated with cardiovascular and malignant diseases. The pathogenesis of hypercoagulability is multifactorial. The basic physiological mechanism is the imbalance between anticoagulant activities and procoagulant activities in hemostatic system. In this review, we discuss the correlation between apoptosis and thrombogenesis in hypercoagulable states. Some cell-associated cofactors in coagulation system, including phosphatidylserine, tissue factor, thrombomodulin and cancer procoagulant, are regulated during apoptosis of various cell types. Vascular endothelial cells may act as one of the most important aspects affecting the balance of anticoagulant and procoagulant activities. When endothelial cells are activated or induced to undergo apoptosis by a number of physiological factors, such as inflammatory cytokines and bacterial lipopolysaccharide, the procoagulant activities of endothelial cells are enhanced. Other cell types such as apoptotic vascular smooth muscle cells, monocytes and macrophages may also contribute to the pathogenesis in atherosclerosis. Apoptotic tumor cells, which express high level of procoagulant activities, may act as a direct trigger for coagulation activation.

Nitric oxide augments release of chemokines from monocytic U937 cells: modulation by anti-inflammatory pathways

Nitric oxide (NO) appears to act as an inflammatory mediator on monocytic cells. Exogenous NO augmented release of chemokines from human promonocytic U937 cells and peripheral blood mononuclear cells. Pharmacological strategies aiming at modulation of NO-induced release of interleukin-8 (IL-8) were investigated in U937 cells in detail. Release of IL-8 was down-regulated by transforming growth factor beta2 (TGF-beta2), by the protein tyrosine-kinase inhibitor genistein, and via rises in intracellular cyclic AMP, generated by prostaglandin E(2), rolipram, pentoxifylline, forskolin, or dibutyryl-cyclic AMP. In addition, incubation with the synthetic glucocorticoid dexamethasone or suppression of activity of p38 mitogen-activated protein (MAP) kinases by SB-203580 modulated release of IL-8. Activation of p38 MAP kinases was confirmed by the demonstration of an augmented appearance of phosphorylated p38 in the presence of NO. The present data suggest that exposure to exogenous NO resembles activation of U937 cells by proinflammatory stimuli. The anti-inflammatory cytokine TGF-beta2, as well as anti-inflammatory or immunosuppressive agents such as genistein, pentoxifylline, rolipram, dexamethasone, and SB-203580 modulate inflammatory, chemokine-inducing actions of NO.

A new apoptotic pathway for the complement factor B-derived fragment Bb

Apoptosis is involved in both the cellular and humoral immune system destroying tumors. An apoptosis-inducing factor from HL-60 myeloid leukemia cells was obtained, purified, and sequenced. The protein found has been identified as a human complement factor B-derived fragment Bb, although it is known that factor B is able to induce apoptosis in several leukemia cell lines. Monoclonal antibodies against fragment Ba and Bb inhibited the apoptotic activity of factor B. When the purified fragment Bb was used for apoptosis induction, only the anti-Bb antibody inhibited Bb-induced apoptosis, and not the anti-Ba antibody. The apoptosis-inducing activity was found to be enhanced under conditions facilitating the formation of Bb. Blocking TNF/TNFR or FasL/Fas interactions did not interfere with the factor B-induced apoptosis. CD11c (iC3bR) acts as the main subunit of a heterodimer binding to fragment Bb in the apoptosis pathway, and the factor B-derived fragment Bb was found to possess the previously unknown function of inducing apoptosis in leukemic cells through a suicide mechanism of myeloid lineage cells during the differentiation stage.

Methotrexate causes apoptosis in postmitotic endothelial cells

Methotrexate (MTX) is a commonly used chemotherapy agent for a variety of cancers. However, therapeutic levels are associated with numerous untoward effects such as central nervous system damage in children with acute lymphoblastic leukemia. The purpose of this study was to determine if MTX caused injury to endothelial cells using cultured bovine pulmonary artery endothelial cells as a model. Light microscopy showed gaps between cells and reduced numbers of endothelial cells after exposure to MTX (10(-9) to 10(-5) M), a range consistent with therapeutic drug levels. Proliferation and viability of subconfluent and confluent MTX-treated endothelial cells were measured by colorimetric (MTS) assay. There was a significant decline in cell numbers in MTX-treated subconfluent (growing) cells cultured after 4 days of MTX exposure compared to controls, as expected. However, there was also an unexpected decline in cell numbers in MTX-treated postmitotic endothelial cells after 1, 3, and 4 days of drug exposure. This suggested that MTX induced endothelial cell death. Fluorescent ApoAlert Enhanced Annexin-V binding demonstrated apoptosis in endothelial cells after 1 day of MTX exposure. Apoptosis was confirmed by a DNA fragment assay. This is apparently the first report of MTX-induced apoptosis of postmitotic, cultured endothelial cells. The findings suggest that apoptosis may be one mechanism of MTX-induced injury to endothelial cells.

Interleukin 8 (IL-8) and the release of leukocytes from the bone marrow

Interleukin 8 (IL-8) is produced by various cells upon stimulation and influences a variety of functions of leukocytes in particular neutrophils. Systemic administration of IL-8 induces a rapid neutropenia associated by sequestration of neutrophils in the lung that is followed by a neutrophilia characterized by the rapid release of neutrophils from the bone marrow. These cells are released predominantly from the bone marrow venous sinusoids. In addition, several studies have shown the potential role of IL-8 in hematopoiesis and trafficking of hematopoietic stem cells. Systemic administration of IL-8 induces a rapid mobilization of progenitors from the bone marrow with long-term myelo-lymphoid repopulation capacity. It has been employed clinically to mobilize hematopoietic progenitor cells into the peripheral blood and used for autologous or allogeneic bone marrow transplantation. The mechanism for these effects of IL-8 is largely speculative. This report summarizes current ideas on the possible mechanisms how IL-8 influences cell trafficking in and from the bone marrow.

Acute myeloid leukaemia triggering via CD40 induces leukocyte chemoattraction and cytotoxicity against allogenic or autologous leukemic targets

The CD40 antigen is a member of the tumor necrosis factor receptor superfamily which interacts with its ligand and regulates the immune response via a dialogue between T-lymphocytes and antigen-presenting or tumor cells. Tumor triggering via CD40 exerts direct effects on cancer cells, which have mainly been investigated in terminally differentiated hematological malignancies such as low-grade lymphoma. We focused our attention on minimally differentiated acute myeloid leukemia (AML-M0), an aggressive hematological malignancy in which severe prognosis suggests the requirement for innovative therapeutic strategies. Here we demonstrate, for the first time to our knowledge, a CD40-triggered IL-8, RANTES and IL-12 secretion by leukemic cells. Supernatants from CD40-stimulated leukemia cells had chemoattractant effects on T-lymphocytes, natural killer cells and monocytes. Moreover, these supernatants, when complemented with low-dose IL-2, induced significant lymphokine-activated and natural killer cytotoxicity, leading to leukemia lysis both in allogenic HLA-matched and autologous settings. Stimulation of leukemia cells via CD40 could participate significantly to the anti-leukemia immune response by contributing to the development of an inflammatory response and to in situ cytotoxicity. Leukemia(2000) 14, 123-128.