The in vivo expression of membrane-bound CD14 in periodontal health and disease

BACKGROUND

Membrane-bound CD14 (mCD14) is a myeloid differentiation antigen expressed on monocytes/macrophages and neutrophils. It is a key molecule responsible for the innate recognition of bacteria by host cells and functions as an important receptor for bacterial lipopolysaccharide. This study investigated the in vivo expression profile and levels of mCD14 in healthy and diseased gingival tissues.

METHODS

Gingival biopsies were obtained from 24 patients with chronic periodontitis, including 22 periodontal pocket tissues, 13 clinically healthy tissues, and 18 inflamed connective tissues (i.e., granulation tissues). Gingival biopsies from seven periodontally healthy subjects were used as controls. mCD14 was detected by immunohistochemistry.

RESULTS

mCD14 was detected in 21 of 22 periodontal pocket tissues and all other categories of tissues. The mCD14-positive cells were mainly confined to the gingival epithelium-connective tissue interface. The expression levels in periodontally healthy subjects were significantly higher than in the patients. Within the patients, clinically healthy tissues showed greater levels of mCD14 than periodontal pocket tissues and granulation tissues.

CONCLUSIONS

mCD14 was commonly expressed in both healthy and diseased gingival tissues and was predominantly confined to the epithelium-connective tissue interface. The positive relationship observed between mCD14 expression levels and periodontal health may imply that mCD14 is associated with favorable host responses to bacterial challenge and contributes to maintaining periodontal homeostasis.

Differential regulation of resveratrol on lipopolysacchride-stimulated human macrophages with or without IFN-γ pre-priming

Resveratrol, a polyphenol compound found in grapes and red wines, is a prominent anti-cancer agent. In this study, we demonstrate that resveratrol enhanced TNF-alpha, IL-12 and IL-1beta production from LPS activated phorbol myristate acetate (PMA) differentiated THP-1 human macrophages. Expression of CD86 on macrophages was enhanced by resveratrol alone and with LPS. When macrophages were primed with IFN-gamma, resveratrol suppressed the expression of HLA-ABC, HLA-DR, CD80, CD86 and inhibited production of TNF-alpha, IL-12, IL-6 and IL-1beta induced by LPS. The differential impact of resveratrol on expression of CD14 might be correlated with differential response of macrophages to LPS with or without IFN-gamma priming.

A CD14 promoter polymorphism is associated with CD14 expression and Chlamydia-stimulated TNFα production

CD14, a pattern recognition receptor on monocyte and macrophage, plays a central role in innate immunity through recognition of bacterial lipopolysaccharide and initiation of inflammatory response. Recently, CD14/-260C>T promoter gene polymorphism has been found to be related to a risk of inflammatory diseases. Our results showed that the C allele frequency among Chinese in Taiwan was lower than those in Western countries. The membrane CD14 expression was significantly higher in TT as compared with CT and CC genotypes (P=0.034, 0.044, respectively). There was a higher level of soluble CD14 in TT and CT genotypes than in CC genotypes. In addition, TNFalpha production in whole blood was significantly higher in TT genotype than in CC genotype after stimulation by Chlamydiae. In conclusion, the single base pair polymorphism of CD14 promoter gene is associated with CD14 expression and Chlamydia-stimulated TNFalpha production, and may thus play some role in the chlamydia-induced inflammatory response.

The effect of local anesthetics on monocyte mCD14 and human leukocyte antigen-DR expression

It has been demonstrated that local anesthetics have several effects on the immune system. Monocytes and macrophages are essential components of the host response to microbial infection; however, the effect of local anesthetics on monocyte surface receptor expression remains unclear. We designed this study to investigate the effects of local anesthetics on monocyte mCD14 and human leukocyte antigen (HLA)-DR expression and lipopolysaccharide (LPS)-induced or staphylococcal enterotoxin B (SEB)-induced tumor necrosis factor (TNF)-alpha production. Blood samples were obtained from 10 healthy volunteers. The effects of local anesthetics on LPS- or SEB-induced TNF-alpha production were determined by using an enzyme-linked immunosorbent assay. After different doses of local anesthetics were added, the blood was stimulated with LPS (10 ng/mL) or SEB (10 micro g/mL) for 4 h. The effects of local anesthetics on monocyte mCD14 and HLA-DR expression were measured by dual monoclonal antibody staining and flow cytometry. Local anesthetics showed no effect on LPS- or SEB-induced TNF-alpha production in human whole blood. Local anesthetics suppressed monocyte HLA-DR expression in a dose-dependent manner (P < 0.05) but had no effect on monocyte mCD14 expression. This study demonstrated that local anesthetics suppress HLA-DR expression on the surface of human monocytes.

IMPLICATIONS

Monocyte surface receptors have a crucial role in the host response to microbial infection. We investigated the effects of local anesthetics on monocyte mCD14 and human leukocyte antigen (HLA)-DR expression. Our results show that local anesthetics suppress HLA-DR expression on the surface of human monocytes.

Dexamethasone inhibits IL-12p40 production in lipopolysaccharide-stimulated human monocytic cells by down-regulating the activity of c-Jun N-terminal kinase, the activation protein-1, and NF-kappa B transcription factors

IL-12 plays a critical role in the development of cell-mediated immune responses and in the pathogenesis of inflammatory and autoimmune disorders. Dexamethasone (DXM), an anti-inflammatory glucocorticoid, has been shown to inhibit IL-12p40 production in LPS-stimulated monocytic cells. In this study, we investigated the molecular mechanism by which DXM inhibits IL-12p40 production by studying the role of the mitogen-activated protein kinases (MAPKs), and the key transcription factors involved in human IL-12p40 production in LPS-stimulated monocytic cells. A role for c-Jun N-terminal kinase (JNK) MAPK in LPS-induced IL-12p40 regulation in a promonocytic THP-1/CD14 cell line was demonstrated by using specific inhibitors of JNK activation, SP600125 and a dominant-negative stress-activated protein/extracellular signal-regulated kinase kinase-1 mutant. To identify transcription factors regulating IL-12p40 gene transcription, extensive deletion analyses of the IL-12p40 promoter was performed. The results revealed the involvement of a sequence encompassing the AP-1-binding site, in addition to that of NF-kappaB. The role of AP-1 in IL-12p40 transcription was confirmed by using antisense c-fos and c-jun oligonucleotides. Studies conducted to understand the regulation of AP-1 and NF-kappaB activation by JNK MAPK revealed that both DXM and SP600125 inhibited IL-12p40 gene transcription by inhibiting the activation of AP-1 and NF-kappaB transcription factors as revealed by luciferase reporter and gel mobility shift assays. Taken together, our results suggest that DXM may inhibit IL-12p40 production in LPS-stimulated human monocytic cells by down-regulating the activation of JNK MAPK, the AP-1, and NF-kappaB transcription factors.

Escherichia coli LPS induces heat shock protein 25 in intestinal epithelial cells through MAP kinase activation

Protection of colonic epithelial integrity and function is critical, because compromises in mucosal functions can lead to adverse and potentially life-threatening effects. The gut flora may contribute to this protection, in part, through the sustained induction of cytoprotective heat shock proteins (HSPs) in surface colonocytes. In this study, we investigated whether Escherichia coli LPS mediates bacteria-induced HSP by using cultured young adult mouse colon (YAMC) cells, an in vitro model of the colonic epithelium. E. coli LPS led to an epithelial cell-type specific induction of HSP25 in a time- and concentration-dependent manner, an effect that did not involve changes in HSP72. YAMC cells expressed the toll-like receptors (TLR)2 and TLR4 but not the costimulatory CD14 molecule. Whereas LPS stimulated both the p38 and ERK1/2 but not the stress-activated protein kinase/c-Jun NH(2)-terminal kinase, signaling pathways in the YAMC cells, all three were stimulated in RAW macrophage cells (in which no LPS-induced HSP25 expression was observed). The p38 inhibitor SB-203580 and the MAP kinase kinase-1 inhibitor PD-98059 inhibited HSP25 induction by LPS. LPS treatment also conferred protection against actin depolymerization induced by the oxidant monochloramine. The HSP25 dependence of the LPS protective effect was outlined in inhibitor studies and through adenovirus-mediated overexpression of HSP25. In conclusion, LPS may be an important mediator of enteric bacteria-induced expression of intestinal epithelial HSP25, an effect that may contribute to filamentous actin stabilization under physiological as well as pathophysiological conditions and thus protection of colonic epithelial integrity.

Saucernetin-7 isolated from Saururus chinensis inhibits proliferation of human promyelocytic HL-60 leukemia cells via G0/G1 phase arrest and induction of differentiation

In the present study, we investigated the in vitro effect of saucernetin-7, which is a dineolignan isolated from Saururus chinensis, on the proliferation, cell cycle-regulation and differentiation of HL-60 human promyelocytic leukemia cells. Saucernetin-7 potently inhibited the proliferation of HL-60 cells in both a dose- and time-dependent manner with an IC50, approximately 5 microM. DNA flow-cytometry indicated that saucernetin-7 markedly induced a G1 phase arrest of HL-60 cells. Among the G1 phase cell cycle-related proteins, the levels of cyclin-dependent kinase (CDK)6 and cyclin D1 were reduced by saucernetin-7, whereas the steady-state levels of CDK2, CDK4, cyclin D2, cyclin D3 and cyclin E were unaffected. The protein and mRNA levels of a CDK inhibitor p21CIP1/WAF1, but not p27KIP1, were markedly increased by saucernetin-7 and p21CIP1/WAF1 induction is likely to occur at the transcriptional level because actinomycin D blocked this induction. In addition, saucernetin-7 markedly enhanced the binding of p21CIP1/WAF1 with CDK2 and CDK6, resulting in the reduced activity of both kinases and the hypophosphorylation of Rb protein. We furthermore suggest that saucernetin-7 is a potent inducer of the differentiation of HL-60 cells, based on observations such as a reduction of the nitroblue tetrazolium level, an increase in the esterase activities and phagocytic activity, morphology changes, and the expression of CD14 and CD66b surface antigens. In conclusion, the onset of saucernetin-7-induced the G0/G1 arrest of HL-60 cells prior to the differentiation is linked to a sharp up-regulation of the p21CIP1/WAF1 level and a decrease in the CDK2 and CDK6 activities. This is the first report demonstrating that saucernetin-7 potently inhibits the proliferation of human promyelocytic HL-60 cells via the G1 phase cell cycle arrest and differentiation induction.

On the mechanism and significance of ligand-induced internalization of human neutrophil chemokine receptors CXCR1 and CXCR2

It is well established that leukocyte chemotactic receptors, a subset of G protein-coupled receptors, undergo endocytosis after stimulation by ligand. However, the significance of this phenomenon to cell motility and other important leukocyte functions induced by chemoattractants has not been clearly defined. Here we show that in primary human neutrophils, the threshold levels of agonist required for endocytosis of the chemotactic receptors CXCR1 and CXCR2 were approximately 10-fold or higher than those needed for maximal chemotactic and calcium flux responses. Moreover, when stimulated by agonists at concentrations that are high enough for chemotaxis but too low for receptor endocytosis, neutrophil CXCR1 and CXCR2 could be reactivated in response to repeated application of the same agonist. Both receptors were excluded from Triton X-100-insoluble lipid rafts, and at high agonist concentrations were rapidly endocytosed by a clathrin/rab5/dynamin-dependent pathway. These data support the conclusion that neutrophil migration in response to CXCR1 or CXCR2 agonists is not dependent on endocytosis of CXCR1 or CXCR2. Rather than being integral to the process of cell migration, receptor endocytosis may be a terminal stop signal when cells reach the focus of inflammation where the chemoattractant concentrations are the highest.

Dichotomy between Lactobacillus rhamnosus and Klebsiella pneumoniae on dendritic cell phenotype and function

The reaction of the intestinal immune system to intestinal bacteria shows striking differences between various bacterial strains. Whereas Klebsiella pneumoniae induces a fierce proinflammatory reaction, the probiotic strain Lactobacillus rhamnosus has clear anti-inflammatory effect in gastrointestinal disease and allergy. The molecular basis for this dichotomy is poorly understood but is likely to involve different modulation of antigen-presenting dendritic cells (DC) by L. rhamnosus and K. pneumoniae. Hence we evaluated phenotypic and functional characteristics of DC matured in the presence of L. rhamnosus and K. pneumoniae. Monocyte-derived immature DC were cultured in the presence of live bacteria to obtain mature DC. Both micro-organisms induced maturation of immature DC as shown by CD83 and CD86 expression, but receptors involved in activation of Th1 cells were expressed predominantly on DC exposed to K. pneumoniae. In contrast to K. pneumoniae, maturation with L. rhamnosus resulted in lower TNF-alpha, IL-6, and IL-8 production by immature DC and lower IL-12 and IL-18 production by mature DC. Moreover, L. rhamnosus led to the development of T cells without a typical Th phenotype whereas K. pneumoniae induced a Th1 immune response, dependent mainly on IL-12 production. Thus our results strongly support the concept that differential modulation of DC explains the differences in the immune response to various bacterial strains and indicates that K. pneumoniae induces Th1 immune responses via DC.

Intravenous immunoglobulin inhibits NF-kappaB activation and affects Fcgamma receptor expression in monocytes/macrophages

High-dose intravenous immunoglobulin (IVIG) therapy is well established as a standard therapy for Kawasaki disease (KD) that reduces the risk of developing coronary artery aneurysms. Activation of monocytes/macrophages and tumor necrosis factor-alpha (TNF-alpha) activity are responsible for severe vascular injury in acute KD. We examined whether or not IVIG inhibits TNF-alpha-induced activation of transcription factor NF-kappaB, a factor that is essential for the expression of proinflammatory cytokines, in human monocytic U-937 cells. The inhibitory effect of IVIG on NF-kappaB activation induced by TNF-alpha was evaluated by Western blotting and flow cytometry. In addition, we examined the effect of IVIG on the expression of FcgammaIII (CD16) and FcgammaRIIb (CD32b) in U-937 cells and peripheral blood CD14+ monocytes/macrophages by flow cytometry. Western blotting demonstrated that IVIG inhibits NF-kappaB activation in U-937 cells, and flow cytometry that IVIG inhibits NF-kappaB activation in U-937 cells in a dose-related manner. Western blotting of cytoplasmic extracts of U-937 cells revealed that IVIG inhibited degradation of the IkappaBalpha protein. Moreover, flow cytometry demonstrated that IVIG decreased the expression of FcgammaRIII in U-937 cells and peripheral blood CD14+ monocytes/macrophages. However, Western blotting revealed that IVIG did not affect the quantity of FcgammaRIII protein, and PCR that IVIG did not affect the quantity of FcgammaRIII mRNA in the cells. These findings suggest that IVIG inhibits TNF-alpha-induced NF-kappaB activation in monocytes/macrophages, and blocks FcgammaRIII on the membranes of monocytes/macrophages.

Tetrahydrobiopterin biosynthesis in white and brown adipose tissues is enhanced following intraperitoneal administration of bacterial lipopolysaccharide

Tetrahydrobiopterin is an essential cofactor for nitric oxide synthase (NOS). This study was undertaken to examine the effects of intraperitoneally injected lipopolysaccharide on tetrahydrobiopterin biosynthesis in murine white and brown adipose tissues. Tetrahydrobiopterin content, catalytic activity and mRNA expression level of GTP cyclohydrolase I (GCH), rate-controlling enzyme in de novo biosynthesis of tetrahydrobiopterin, in both adipose tissues were up-regulated by 500-microg lipopolysaccharide at 6 h after the injection. On the contrary, treatment of 3T3-L1 adipocytes with lipopolysaccharide alone did not affect GCH mRNA expression level, whereas the combination of lipopolysaccharide, tumor necrosis factor (TNF)-alpha, and interferon gamma induced the increase in expression levels of GCH mRNA and CD14 mRNA. Collectively, our results showed that tetrahydrobiopterin biosynthesis can be augmented by increased GCH activity caused by a synergistic effect of lipopolysaccharide and cytokines in white and brown adipose tissues. These observations support the view that tetrahydrobiopterin biosynthesis in the adipose tissues is a target of inflammatory events triggered by peripheral LPS injection.

Involvement of CD14 and Toll-Like Receptor 4 in the Acute Phase Response of Serum Amyloid A Proteins and Serum Amyloid P Component in the Liver After Burn Injury

Acute phase proteins such as serum amyloid A proteins (SAAs) and serum amyloid P component (SAP) are induced in the liver after various insults (e.g., infection, injury). The cellular and molecular mechanisms controlling the expression of these acute phase proteins may be specifically designed for different insults. The roles of two central molecules of the lipopolysaccharide (LPS)-mediated inflammation pathway (CD14 and toll-like receptor 4 [Tlr4]) were investigated for the regulation of SAAs and SAP in the liver of mice after an 18% total body surface area burn injury. RT-PCR analysis revealed a subtype- and time-dependent induction of SAA mRNAs between 3 h and 3 days, while there was a peak induction of SAP mRNA at day 1. Marked elevations of SAA and SAP protein levels at day 1 supported the mRNA data. Furthermore, a differential regulation of SAAs and SAP mRNAs was noted between CD14 knockout (KO) and their control mice after injury. SAA protein was induced to a lesser degree after injury in C3H/HeJ (Tlr4-defective) mice than in their control mice. In addition, in both CD14 KO and C3H/HeJ mice, the induction of SAP protein was significantly reduced compared with respective controls. These data provide evidence that CD14 and Tlr4 participate, at least in part, in a cascade of signaling events that control the immediate-early and differential induction of SAAs and SAP in the liver after injury. They also suggest that LPS may be one of the initial inducing agents associated with these acute phase responses in the liver after injury.

Localization of GPI-80, a beta2-integrin-associated glycosylphosphatidyl-inositol anchored protein, on strongly CD14-positive human monocytes

Human monocyte/macrophage systems are extremely heterogeneous. Although many attempts have been made to define monocyte subpopulations, few antigens distinguish them. We previously reported that GPI-80, a novel glycosylphosphatidyl-inositol (GPI)-anchored protein that is expressed mainly on human neutrophils regulates neutrophil adherence and migration, and that GPI-80 is expressed on monocytes. In this study, we examined the precise distribution of GPI-80-positive monocytes using flow cytometry. Using anti-CD14 and anti-CD16 mAbs, almost all GPI-80-bearing monocytes belong to the strongly CD14-positive monocyte subpopulation. Furthermore, flow cytometric analysis of GPI-80 and other monocyte markers revealed that GPI-80 expression was high in CD11b-, CD32-, and CD64-positive monocytes. In contrast, GPI-80 expression was low in HLA-DQ-positive monocytes. These results suggest that almost all GPI-80 positive monocytes belong to a monocyte subpopulation that is superior in phagocytosis and reactive oxygen production, but inferior in antigen presentation. GPI-80 may be a useful antigen for classifying monocytes into subpopulations.

Synergistic effects of lipopolysaccharide and interferon-gamma in inducing interleukin-8 production in human monocytic THP-1 cells is accompanied by up-regulation of CD14, Toll-like receptor 4, MD-2 and MyD88 expression

Lipopolysaccharide (LPS) and interferon (IFN)-gamma synergistically induced interleukin-8 (IL-8) production in human monocytic THP-1 cells. IFN-gamma-primed THP-1 cells produced higher levels of IL-8 on stimulation with LPS than non-primed cells and the level correlated with duration of priming up to 24 h, although the level of IL-8 induced was most comparable to that induced by co-stimulation with LPS and IFN-gamma. Unstimulated THP-1 cells were shown by flow cytometry to be practically devoid of membrane CD14 (mCD14). LPS and IFN-gamma enhanced mCD14 and Toll-like receptor (TLR) 4 expression in THP-1 cells, respectively, and co-stimulation with LPS and IFN-gamma induced higher levels of mCD14 and TLR4 expression than stimulation with either agent alone. LPS and IFN-gamma alone each augmented MD-2 and MyD88 mRNA expression in THP-1 cells, and co-stimulation with LPS and IFN-gamma markedly enhanced MD-2 and MyD88 mRNA expression in the cells compared to those with either LPS or IFN-gamma alone. Anti-CD14 and anti-TLR4 monoclonal antibodies almost completely inhibited IL-8 production induced by LPS plus IFN-gamma in THP-1 cells. These findings suggest that combined stimulation of THP-1 cells with LPS and IFN-gamma up-regulate mCD14, TLR4, MD-2 and MyD88 expression by these cells, which might be involved in synergistic IL-8 production by the cells.

[Expression of the lipopolysaccharide receptors in the rat liver cells in inflammation and in norm]

The liver can be a primary target organ for bacterial endotoxins--lipopolysaccharides, which serve as the major triggers of anaphylotoxin's generation. Both lipopolysaccharides and anaphylotoxins induce the acute-phase reaction in the liver. The acute-phase reaction comprises a variety of systemic changes. Synthesis of several plasma proteins in the liver and glucose output from hepatocytes undergo dramatic changes during inflammation. These changes are mediated by soluble factors. Mechanism of signal transduction is reviewed in detail. Attention is payed to the differences between expression of the lipopolysaccharide receptors under normal and inflammatory conditions.

The role of monocytes/macrophages in TCR-zeta chain downregulation and apoptosis of T lymphocytes in malignant pleural effusions

The aim of this study was to assess alterations of zeta chain expression and their relation to apoptosis of T lymphocytes. T lymphocytes were obtained from malignant pleural effusions (MPE) of 15 patients. The work focused on TCR-zeta chain expression, apoptosis of T lymphocytes, and on the content of monocyte/macrophages in effusions. Analysis was performed using three color flow cytometry combining CD3, TCR-zeta and TUNEL reaction. The content of tumor and monocyte/macrophage cells has been determined using CD3, CD14, and cytokeratins, as markers of distinct cell subpopulations. Our findings strongly indicate that decreased zeta chain expression in T cells depends on the content of monocyte/macrophage cells, and that the range of the decrease is inversely proportional to the number of monocytes/macrophages in the effusion. Those having low zeta chain expression were the main subpopulation of T cells undergoing apoptosis. These data suggest that decreased zeta chain expression in T cells in MPE may be related to the abundance of monocyte/macrophages in effusions.

Detecting and quantifying colocalization of cell surface molecules by single particle fluorescence imaging

Single particle fluorescence imaging (SPFI) uses the high sensitivity of fluorescence to visualize individual molecules that have been selectively labeled with small fluorescent particles. The positions of particles are determined by fitting the intensity profile of their images to a 2-D Gaussian function. We have exploited the positional information obtained from SPFI to develop a method for detecting colocalization of cell surface molecules. This involves labeling two different molecules with different colored fluorophores and determining their positions separately by dual wavelength imaging. The images are analyzed to quantify the overlap of the particle images and hence determine the extent of colocalization of the labeled molecules. Simulated images and experiments with a model system are used to investigate the extent to which colocalization occurs from chance proximity of randomly distributed molecules. A method of correcting for positional shifts that result from chromatic aberration is presented. The technique provides quantification of the extent of colocalization and can detect whether colocalized molecules occur singly or in clusters. We have obtained preliminary data for colocalization of molecules on intact cells. Cells often exhibit particulate autofluorescence that can interfere with the measurements; a method for overcoming this problem by triple wavelength imaging is described.

Diverse Origin and Function of Cells With Endothelial Phenotype Obtained From Adult Human Blood

Cells with endothelial phenotype generated from adult peripheral blood have emerging diagnostic and therapeutic potential. This study examined the lineage relationship between, and angiogenic function of, early endothelial progenitor cells (EPCs) and late outgrowth endothelial cells (OECs) in culture. Culture conditions were established to support the generation of both EPCs and OECs from the same starting population of peripheral blood mononuclear cells (PBMCs). Utilizing differences in expression of the surface endotoxin receptor CD14, it was determined that the vast majority of EPCs arose from a CD14 + subpopulation of PBMCs but OECs developed exclusively from the CD14 − fraction. Human OECs, but not EPCs, expressed key regulatory proteins endothelial nitric oxide synthase (eNOS) and caveolin-1. Moreover, OECs exhibited a markedly greater capacity for capillary morphogenesis in in vitro and in vivo matrigel models, tube formation by OECs being in part dependent on eNOS function. Collectively, these data indicate lineage and functional heterogeneity in the population of circulating cells capable of assuming an endothelial phenotype and provide rationale for the investigation of new cell-therapeutic approaches to ischemic cardiovascular disease.

Lysines 128 and 132 enable lipopolysaccharide binding to MD-2, leading to Toll-like receptor-4 aggregation and signal transduction

Three cell-surface proteins have been recognized as components of the mammalian signaling receptor for bacterial lipopolysaccharide (LPS): CD14, Toll-like receptor-4 (TLR4), and MD-2. Biochemical and visual studies shown here demonstrate that the role of CD14 in signal transduction is to enhance LPS binding to MD-2, although its expression is not essential for cellular activation. These studies clarify how MD-2 functions: we found that MD-2 enables TLR4 binding to LPS and allows the formation of stable receptor complexes. MD-2 must be bound to TLR4 on the cell surface before binding can occur. Consequently, TLR4 clusters into receptosomes (many of which are massive) that recruit intracellular toll/IL-1/resistance domain-containing adapter proteins within minutes, thus initiating signal transduction. TLR4 activation correlates with the ability of MD-2 to bind LPS, as MD-2 mutants that still bind TLR4, but are impaired in the ability to bind LPS, conferred a greatly blunted LPS response. These findings help clarify the earliest events of TLR4 triggering by LPS and identify MD-2 as an attractive target for pharmacological intervention in endotoxin-mediated diseases.

Coordinated but depressed expression of human leukocyte antigen-DR, intercellular adhesion molecule-1, and CD14 on peritoneal macrophages in women with pelvic endometriosis

OBJECTIVE

To investigate the macrophage response in endometriosis, we determined the expression of human leukocyte antigen (HLA)-DR, intercellular adhesion molecule (ICAM)-1, and CD14 on peritoneal macrophages.

DESIGN

Case-control study of immunologic markers.

SETTING

University hospital.

PATIENT(S)

Forty-five Japanese women with endometriosis were compared with 48 control subjects with other laparoscopic diagnoses.

INTERVENTION(S)

Venipuncture and laparoscopic peritoneal fluid (PF) collection.

MAIN OUTCOME MEASURE(S)

Expression of HLA-DR, ICAM-1, and CD14 on peripheral blood (PB) monocytes and PF macrophages were quantitated as mean fluorescence intensities by flow cytometry. Expression of each marker on PF macrophages was divided by that on PB monocytes, as an index of macrophage activation (macrophage activation ratio).

RESULT(S)

In women with endometriosis, PF macrophages showed significant positive correlations between expression of HLA-DR and ICAM-1, HLA-DR and CD14, and ICAM-1 and CD14. However, expression of individual markers on PF macrophages and their activation ratios were significantly lower than in control.

CONCLUSION(S)

Coordinated but relatively low expression of HLA-DR, ICAM-1, and CD14 on PF macrophages indicates a positive but limited immune response to events in the peritoneal cavity in women with endometriosis, which may induce immune tolerance to implanted or metaplastic endometrial tissue.

The 'Immunological-Synapse' at its APC side in relapsing and secondary-progressive multiple sclerosis: modulation by interferon-β

Reciprocal interactions between T cells and antigen-presenting cells (APCs) within the 'Immunological-Synapse' (IS) govern immune cell autoreactivity in multiple sclerosis (MS). The present study examined the expression of a range of co-stimulatory molecules: CD40, CD54, CD80, CD86 and HLA-DR, on the cell-surface of CD14(+) peripheral blood monocytes (PBM) from relapsing-remitting (RR) and secondary-progressive (SP)-MS patients, prior to and during 1 year of Interferon (IFN)-beta-1a (Rebif(R)) therapy. Prior to treatment, patients from both MS subtypes expressed elevated CD80 and reduced CD40 levels in comparison to controls. CD86 expression was significantly reduced in SP compared to RR patients and controls. IFN-beta therapy led to a significant reduction in the expression of CD54 and CD80 in both groups of patients as well as to elevation of CD40 and CD86 expression in SP patients. These results confirm IFN-mediated modulation of the APC surface within the immunological-synapse and implicate CD80 and CD86 as targets for interventional therapies in MS as well as other Th1-mediated autoimmune diseases.

Pregnancy induces minor histocompatibility antigen-specific cytotoxic T cells: implications for stem cell transplantation and immunotherapy

Recipients of HLA-identical stem cell transplants have a poorer transplant outcome if the donor is female rather than male. We analyzed whether pregnancy primes for minor histocompatibility (H) antigens. Peripheral blood mononuclear cells (PBMCs) from healthy multiparous female blood donors were depleted for CD4+, CD14+, CD16+, and CD19+ cells, stained with minor H antigen-specific HLA-A2 tetramers, sorted by fluorescence-activated cell sorting, and tested for cytotoxic activity. Minor H antigens HY-, HA-1-, and HA-2-specific cytotoxic T cells (CD8+, CD45RA-) were present in PBMCs from 4 of 7 female donors up to 22 years after the last delivery. Interestingly, in 2 of the 4 cases microchimerism of the putative immunizing minor H antigen was observed. Thus, pregnancy can lead to alloimmune responses against the infant's paternal minor H antigens. The minor H antigen immunization status of female donors raises important questions for the clinical practice of stem cell transplantation.

Relevance of monocytic features for neovascularization capacity of circulating endothelial progenitor cells

BACKGROUND

Transplantation of ex vivo expanded circulating endothelial progenitor cells (EPCs) from peripheral blood mononuclear cells improves the neovascularization after critical ischemia. However, the origin of the endothelial progenitor lineage and its characteristics have not yet been clearly defined. Therefore, we investigated whether the phenotype and functional capacity of EPCs to improve neovascularization depend on their monocytic origin.

METHODS AND RESULTS

Monocytic CD14+ cells were isolated from mononuclear cells and incubated on fibronectin-coated dishes in endothelial medium in the presence of vascular endothelial growth factor. After 4 days of cultivation, adherent cells deriving from CD14+ or CD14- mononuclear cells showed equal expression of endothelial marker proteins and capacity for clonal expansion as determined by measuring endothelial colony-forming units. In addition, transplanted EPCs (5x10(5) cells) deriving from CD14+ or CD14- cells were incorporated into vascular structures of nude mice after hind-limb ischemia and significantly improved neovascularization from 0.27+/-0.12 (no cells) to 0.66+/-0.12 and 0.65+/-0.17, respectively (P<0.001; laser Doppler-derived relative blood flow). In contrast, no functional improvement of neovascularization was detected when freshly isolated CD14+ mononuclear cells without ex vivo expansion were used (0.33+/-0.17). Moreover, macrophages or dendritic cells differentiated from isolated CD14+ cells were significantly less effective in improving neovascularization than EPCs cultivated from the same starting population (P<0.01).

CONCLUSIONS

These data demonstrate that EPCs can be generated from nonmonocytic CD14- peripheral blood mononuclear cells and exhibit a unique functional activity to improve neovascularization after hind-limb ischemia.

Smooth muscle cells in human atherosclerotic plaques express the fractalkine receptor CX3CR1 and undergo chemotaxis to the CX3C chemokine fractalkine (CX3CL1)

BACKGROUND

Chemokines are important mediators of inflammatory cell recruitment that play a significant role in atherosclerosis. Fractalkine (CX3CL1) is an unusual membrane-bound chemokine that mediates chemotaxis through the CX3CR1 receptor. Recently, functional polymorphisms in the human CX3CR1 gene have been described that are associated with coronary artery disease.

METHODS AND RESULTS

We investigated the expression of the CX3C chemokine fractalkine and its receptor CX3CR1 in human coronary artery plaques by immunocytometry. We show that a subset of mononuclear cells expresses high levels of fractalkine in human coronary atherosclerotic plaques and that smooth muscle cells within the neointima express the fractalkine receptor CX3CR1. There is a positive correlation between the number of fractalkine-expressing cells and the number of CX3CR1-positive cells in human atherosclerotic plaques (r=0.70, n=15 plaques). Furthermore, we demonstrate that cultured vascular smooth muscle cells express the CX3CR1 receptor and undergo chemotaxis to fractalkine that can be inhibited by G protein inactivation by pertussis toxin.

CONCLUSIONS

These results suggest that in human atherosclerosis, fractalkine, rather than mediating inflammatory cell recruitment, can act as a mediator of smooth muscle cell migration.

Relevance of monocytic features for neovascularization capacity of circulating endothelial progenitor cells

BACKGROUND

Transplantation of ex vivo expanded circulating endothelial progenitor cells (EPCs) from peripheral blood mononuclear cells improves the neovascularization after critical ischemia. However, the origin of the endothelial progenitor lineage and its characteristics have not yet been clearly defined. Therefore, we investigated whether the phenotype and functional capacity of EPCs to improve neovascularization depend on their monocytic origin.

METHODS AND RESULTS

Monocytic CD14+ cells were isolated from mononuclear cells and incubated on fibronectin-coated dishes in endothelial medium in the presence of vascular endothelial growth factor. After 4 days of cultivation, adherent cells deriving from CD14+ or CD14- mononuclear cells showed equal expression of endothelial marker proteins and capacity for clonal expansion as determined by measuring endothelial colony-forming units. In addition, transplanted EPCs (5x10(5) cells) deriving from CD14+ or CD14- cells were incorporated into vascular structures of nude mice after hind-limb ischemia and significantly improved neovascularization from 0.27+/-0.12 (no cells) to 0.66+/-0.12 and 0.65+/-0.17, respectively (P<0.001; laser Doppler-derived relative blood flow). In contrast, no functional improvement of neovascularization was detected when freshly isolated CD14+ mononuclear cells without ex vivo expansion were used (0.33+/-0.17). Moreover, macrophages or dendritic cells differentiated from isolated CD14+ cells were significantly less effective in improving neovascularization than EPCs cultivated from the same starting population (P<0.01).

CONCLUSIONS

These data demonstrate that EPCs can be generated from nonmonocytic CD14- peripheral blood mononuclear cells and exhibit a unique functional activity to improve neovascularization after hind-limb ischemia.

An inhibitor of the EGF receptor family blocks myeloma cell growth factor activity of HB-EGF and potentiates dexamethasone or anti-IL-6 antibody-induced apoptosis

We previously found that some myeloma cell lines express the heparin-binding epidermal growth factor-like growth factor (HB-EGF) gene. As the proteoglycan syndecan-1 is an HB-EGF coreceptor as well as a hallmark of plasma cell differentiation and a marker of myeloma cells, we studied the role of HB-EGF on myeloma cell growth. The HB-EGF gene was expressed by bone marrow mononuclear cells in 8 of 8 patients with myeloma, particularly by monocytes and stromal cells, but not by purified primary myeloma cells. Six of 9 myeloma cell lines and 9 of 9 purified primary myeloma cells expressed ErbB1 or ErbB4 genes coding for HB-EGF receptor. In the presence of a low interleukin-6 (IL-6) concentration, HB-EGF stimulated the proliferation of the 6 ErbB1+ or ErbB4+ cell lines, through the phosphatidylinositol 3-kinase/AKT (PI-3K/AKT) pathway. A pan-ErbB inhibitor blocked the myeloma cell growth factor activity and the signaling induced by HB-EGF. This inhibitor induced apoptosis of patients'myeloma cells cultured with their tumor environment. It also increased patients' myeloma cell apoptosis induced by an anti-IL-6 antibody or dexamethasone. The ErbB inhibitor had no effect on the interaction between multiple myeloma cells and stromal cells. It was not toxic for nonmyeloma cells present in patients' bone marrow cultures or for the growth of hematopoietic progenitors. Altogether, these data identify ErbB receptors as putative therapeutic targets in multiple myeloma.

Evidence that HIV budding in primary macrophages occurs through the exosome release pathway

Lipid rafts are specialized regions of cell membranes enriched in cholesterol and sphingolipids that are involved in immune activation and signaling. Studies in T-cells indicate that these membrane domains serve as sites for release of human immunodeficiency virus (HIV). By budding through lipid rafts in T-cells, HIV selectively incorporates raft markers and excludes non-raft proteins. This process has been well studied in T-cells, but it is unknown whether lipid rafts serve as budding sites for HIV in macrophages. Recently, we proposed a new model of retroviral biogenesis called the Trojan exosome hypothesis (Gould, S. J., Booth, A., and Hildreth, J. E. K. (2003) Proc. Natl. Acad. Sci. U. S. A. 100, 10592-10597). This model proposes that retroviruses coopt the existing cellular machinery for exosomal release. Here, we performed the first test designed to differentiate between the lipid raft hypothesis of retroviral biogenesis and the Trojan exosome hypothesis. Using macrophages, we examined the relative abundance of several host proteins on the cell surface, in lipid rafts, and on both HIV particles and exosomes derived from these cells. Our results show significant differences in the abundance of host proteins on the cell surface and in HIV. Moreover, our data demonstrate discordance in the abundance of some proteins in lipid rafts and in HIV. Finally, our data reveal a strong concordance between the host cell protein profile of exosomes and that of HIV. These results strongly support the Trojan exosome hypothesis and its prediction that retroviral budding represents exploitation of a pre-existing cellular pathway of intercellular vesicle trafficking.

Reduced interferon gamma production and soluble CD14 levels in early life predict recurrent wheezing by 1 year of age

It is unknown whether reduced production of IFNgamma in early life, before any lower respiratory tract illness, is a risk factor for recurrent wheezing in infancy. We followed 238 infants prospectively from birth to 1 year of age. At birth and at 3 months of age, IFNgamma production from polyclonally stimulated peripheral blood mononuclear cells and soluble CD14 (sCD14) levels in plasma were measured. The odds of developing recurrent wheezing (assessed by questionnaire) in the first year of life were up to 4.5 times higher for children in the lowest quartile of IFNgamma production at 3 months (p = 0.0005) and 3.2 times higher for children in the lowest quartile of sCD14 levels at birth (p = 0.004) as compared with children in the other 3 combined quartiles of IFNgamma and sCD14, respectively. Findings were confirmed in the multivariate analysis. IFNgamma production at 3 months and sCD14 levels at birth were correlated (r = 0.188, p = 0.031). Our findings from a longitudinal cohort suggest that impaired IFNgamma production at 3 months and reduced plasma-sCD14 levels at birth significantly increase the risk of developing recurrent wheezing in the first year of life.

Leptin, tumor necrosis factor-α (TNF), and CD14 in ovine adipose tissue and changes in circulating TNF in lean and fat sheep2

Four studies were designed to determine whether 1) tumor necrosis factor-alpha (TNF) and the Lipopolysaccharide (LPS) binding ligand, CD14, are produced by sheep adipose tissue; 2) nutritional reserves and/or short-term fasting affect circulating concentrations of TNF; 3) there is a relationship between TNF and metabolic factors in sheep; and 4) inflammation alters circulating concentrations of leptin. In Exp. 1 and 2, ewes were assigned, based on ultrasonic assessments of last-rib subcutaneous fat measurements to fat (fat thickness > 1 cm; mean = 1.52 +/- 0.03 cm) or thin (fat thickness < 1 cm; mean = 0.25 +/- 0.03 cm) groups. Fat and thin ewes were assigned to fed or fasted groups for a total of four groups (fed-fat; fasted-fat; fed-thin; fasted-thin). Fed-ewes had ad libitum access to feed, and fasted-ewes were prohibited feed 48 h before initiation of sample collection. In Exp. 1, subcutaneous fat samples were collected from just above the last rib for detection of TNF and CD14 mRNA, and immunoreactivity. Tumor necrosis factor-alpha-like immunoreactivity in adipocytes was sparse, more pronounced in cells in fed-ewes than fasted-ewes, and localized to membranes between adjacent cells in nucleated regions. Immunoreactivity for CD14 was minimally observed but present in adipocytes and widely expressed in infiltrating monocytes and epithelial vascular cells. Leptin was detected in adipocytes. In Exp. 2, plasma samples collected every 6 h for 24 h were analyzed for plasma concentrations of TNF. Fat ewes had greater plasma concentrations of TNF than thin ewes (P = 0.039). In Exp. 3, wethers were injected i.v. with interleukin-1beta or TNF. Blood samples were collected every 15 min for 8 h following injection. Plasma concentration of leptin was not affected by treatment (P > 0.39). In Exp. 4, wethers were injected with LPS. Blood samples were collected every 15 min for 8 h following injection. Plasma concentration of leptin was not altered by LPS (P > 0.20). These results provide evidence: 1) of TNF-like immunoreactivity within fat tissue; 2) that elements within fatty tissues have CD14 that may allow adipocyte function to be directly affected by LPS; 3) that plasma concentrations of leptin are not altered by LPS treatment; and 4) that circulating concentrations of TNF are elevated with obesity in sheep.

Measurements of associations of cell-surface receptors by single-particle fluorescence imaging

SPFI (single-particle fluorescence imaging) uses the high sensitivity of fluorescence to visualize individual molecules that have been selectively labelled with small fluorescent particles. The images of particles are diffraction-limited spots that are analysed by fitting with a two-dimensional Gaussian function. The spot intensities depend on whether they arise from one or more particles; this provides the basis for determining self-association of cell-surface receptors. We have used this approach to determine dimerization of MHC class II molecules and its disruption by interface peptides. We have also exploited the positional information obtained from SPFI to detect co-localization of cell-surface molecules. This involves labelling two different molecules with different coloured fluorophores and determining their positions separately by dual wavelength imaging. The images are analysed to quantify the overlap of the particle images and hence determine the extent of co-localization of the labelled molecules. The technique provides quantification of the extent of co-localization and can detect whether co-localized molecules occur singly or in clusters. We have obtained preliminary data for co-localization of lipopolysaccharide and CD14 on intact cells. We also show that HLA-DR (human leukocyte antigen-DR) and CD74 are partially co-localized and that interaction between these molecules involves the peptide-binding groove of HLA-DR.

Flow cytometric technique for the detection of phagocytosed wear particles in patients with total joint arthroplasty

Wear particles from prosthetic implants have been shown to cause inflammatory synovitis and periprosthetic osteolysis. These particle-induced pathologies are manifestations of adverse cellular responses to phagocytosed particles. In this study, phagocytosis of polyethylene particles was analyzed using flow cytometry (FCM), and the clinical utility of FCM in diagnosing particle-induced synovitis was examined. Ultra high molecular weight polyethylene particles exhibited natural autofluorescence at fluorescein isothiocyanate wavelengths when determined by FCM. Using this autofluorescent property of the particles, peripheral blood monocytes (PBMs) phagocytosing the particles could be detected by autofluorescence emission from intracellular particles. This autofluorescence from PBMs increased with particles/cell ratio in a dose-dependent manner. Particle phagocytosis was also detectable in joint fluid cells obtained from the patients with particle-induced synovitis following total joint arthroplasty (TJA). Phenotypic analysis indicated that phagocytes were typically CD14(+)CD16(-) macrophages, with occasional CD14(+)CD16(+) macrophages. Interestingly, decreased autofluorescence intensity of CD14(+) cells was observed after arthroscopic drainage, suggesting that FCM was useful in examining whether the treatment was successful. In summary, these results indicate that FCM analysis offers a simple and useful method of detecting phagocytosis of polyethylene particles and estimating the severity of particle-induced synovitis in post-TJA patients.

Prevention of ethanol-induced liver injury in rats by an agonist of peroxisome proliferator-activated receptor-gamma, pioglitazone

Agonists of peroxisome proliferator-activated receptor (PPAR)-gamma have been shown to reduce tumor necrosis factor-alpha (TNF-alpha)-induced insulin resistance. On the other hand, sensitization of Kupffer cells to lipopolysaccharide (LPS) and their production of TNF-alpha are critical for progression of alcoholic liver injury. This study was intended to determine whether pioglitazone, a PPAR-gamma agonist, could prevent alcohol-induced liver injury. Rats were given ethanol (5 g/kg b.wt.) and pioglitazone (500 microg/kg) once every 24 h intragastrically. Ethanol for 8 weeks caused pronounced steatosis, necrosis, and inflammation in the liver. These pathological parameters were diminished greatly by pioglitazone. Kupffer cells were sensitized to LPS after ethanol for 4 weeks as evidenced by aggravation of liver pathology induced by LPS (5 mg/kg) and enhancement of LPS (100 ng/ml)-induced intracellular Ca2+ concentration elevation in Kupffer cells. The parameters were diminished by treatment with pioglitazone. LPS-induced TNF-alpha production by Kupffer cells from the 4-week ethanol group was 3 to 4 times higher than control. This increase was blunted by 70% with pioglitazone. Gut permeability was 10-fold higher in the 4-week ethanol group, and pioglitazone treatment did not change the value. Inclusion of TNF-alpha in culture media of Kupffer cells enhanced CD14 expression, LPS-induced intracellular Ca2+ concentration response, and production of TNF-alpha. These results indicate that pioglitazone prevents alcoholic liver injury through abrogation of Kupffer cell sensitization to LPS.

Toll-like receptor (TLR) 2 and TLR5, but not TLR4, are required for Helicobacter pylori-induced NF-kappa B activation and chemokine expression by epithelial cells

Infection with Helicobacter pylori, a Gram-negative, microaerophilic, flagellated bacteria that adheres to human gastric mucosa, is strongly associated with gastric ulcers and adenocarcinoma. The mechanisms through which gastric epithelial cells recognize this organism are unclear. In this study we evaluated the interactions between the Toll-like receptors (TLRs) and H. pylori-mediated NF-kappa B activation and the induction of chemokine mRNA expression. By reverse transcriptase-PCR we determined that MKN45 gastric epithelial cells express low but detectable amounts of TLR2, -4, and -5 but no MD-2. To determine which, if any, TLRs may play a role in the response of epithelial cells to H. pylori, HEK293 cells were cotransfected with the NF-kappa B-Luc reporter, CD14 and MD2 expression plasmids, and expression plasmids for TLR2, TLR4, or TLR5. Infection of the cultures with H. pylori (strain 26695) induced NF-kappa B activity in cells transfected with TLR2 and TLR5, but not TLR4. Consistent with the HEK293 experiments, H. pylori-induced NF-kappa B activation was decreased in MKN45 gastric epithelial cells by transfection of dominant-negative versions of TLR2 and TLR5 but not TLR4. Highly purified lipopolysaccharide from H. pylori strain 26695 activated NF-kappa B in HEK293 via TLR2 but not TLR4. Partially purified flagellin from H. pylori was also capable of inducing NF-kappa B activation in HEK cells transfected with TLR5. Additionally, chemokine gene expression was induced by H. pylori in HEK293 cells following stable transfection with TLR2 or TLR5 expression plasmids. These studies demonstrate that gastric epithelial cells recognize and respond to H. pylori infection at least in part via TLR2 and TLR5. Furthermore, the unique lipopolysaccharide of H. pylori is a TLR2, not a TLR4 agonist.

Receptors involved in the oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine-mediated synthesis of interleukin-8. A role for Toll-like receptor 4 and a glycosylphosphatidylinositol-anchored protein

We demonstrated previously that oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (ox-PAPC) and, specifically, the component lipid 1-palmitoyl-2-(5,6-epoxyisoprostane E2)-sn-glycero-3-phosphorylcholine increase interleukin-8 (IL-8) synthesis in aortic endothelial cells. The goal of the current studies was to characterize the receptor complex mediating the increased transcription of IL-8. We demonstrate that scavenger receptor class A, types I and II, lectin-like ox-LDL receptor-1, macrophage receptor with collagenous structure, and CD36 are not responsible for the increase in IL-8. Using dominant-negative constructs and antisense oligonucleotides, we demonstrate a role for Toll-like receptor 4 (TLR4) as the ox-PAPC receptor mediating IL-8 transcription. We demonstrate that a glycosylphosphatidylinositol (GPI)-anchored protein is also necessary because phosphatidylinositol-specific phospholipase C pretreatment inhibited the effect of ox-PAPC. CD14, a GPI-anchored protein that associates with TLR4 in mediating lipopolysaccharide action, did not appear to mediate ox-PAPC action because ox-PAPC-induced IL-8 transcription was not blocked by anti-CD14 neutralizing antibodies nor was it augmented by the addition of soluble CD14 or overexpression of membrane CD14. Instead, anti-TLR4 antibodies immunoprecipitated a 37-kDa protein that also bound ox-PAPC. A protein of this same size was found in aerolysin overlays used to detect GPI-anchored proteins. Therefore, these studies suggest that ox-PAPC may initially bind to a 37-kDa GPI-anchored protein, which interacts with TLR4 to induce IL-8 transcription.

Effect of CD14 blockade on endotoxin-induced acute lung injury in mice

CD14 functions as a cell surface receptor for endotoxin (lipopolysaccharide [LPS]) and is thought to have an essential role in innate immune responses to infection. Previous studies have revealed attenuation of the systemic response after sepsis by blocking CD14. In this study, we tested the hypothesis that CD14 blockade protects against inflammatory responses associated with LPS pneumonia. We examined the effect of an anti-murine CD14 monoclonal antibody (4C1) on the development of acute lung injury induced by intratracheal LPS in mice. We also measured the production of cytokines (tumor necrosis factor-alpha, interleukin-6, and macrophage inflammatory protein-2) and nitric oxide by murine peritoneal macrophages exposed to LPS in vitro. Nuclear factor (NF)-kappa B translocation was evaluated in nuclear extracts from lung homogenates. 4C1 significantly attenuated pulmonary edema and neutrophil emigration after LPS administration. The production of cytokines and nitric oxide by LPS-stimulated macrophages was significantly decreased by 4C1 treatment. NF-kappa B translocation induced by LPS instillation was also suppressed by 4C1. These results suggest that blockade of CD14 might attenuate acute lung injury after intratracheal instillation of LPS through the suppression of NF-kappa B translocation. The inhibitory effect of CD14 blockade on cytokine production and nitric oxide release of macrophages might contribute to the attenuation of lung injury.

P-selectin enhances generation of CD14+CD16+ dendritic-like cells and inhibits macrophage maturation from human peripheral blood monocytes

Endothelial cells play a critical role in monocyte differentiation. Platelets also affect terminal maturation of monocytes in vitro. P-selectin is an important adhesion molecule expressed on both endothelial cells and activated platelets. We investigated its effects on human peripheral blood monocyte differentiation under the influence of different cytokines. Generation of dendritic-like cells (DLCs) from peripheral blood monocytes was promoted by immobilized P-selectin in the presence of M-CSF and IL-4 as judged by dendritic cell (DC) morphology; increased expression of CD1a, a DC marker; low phagocytic activity; and high alloreactivity to naive T cells. In contrast to typical DCs, DLCs expressed CD14 and FcgammaRIII (CD16). These features link the possible identity of DLCs to that of an uncommon CD14(+)CD16(+)CD64(-) monocyte subset found to be expanded in a variety of pathological conditions. Functionally, DLCs generated by P-selectin in combination with M-CSF plus IL-4 primed naive allogeneic CD4(+) T cells to produce significantly less IFN-gamma than cells generated by BSA in the presence of M-CSF and IL-4. P-selectin effects on enhancing CD14(+)CD16(+) DLC generation were completely abrogated by pretreatment of cells with the protein kinase C delta inhibitor rottlerin, but not by classical protein kinase C inhibitor Gö6976. Immobilized P-selectin also inhibited macrophage differentiation in response to M-CSF alone as demonstrated by morphology, phenotype, and phagocytosis analysis. The effects of P-selectin on macrophage differentiation were neutralized by pretreatment of monocytes with Ab against P-selectin glycoprotein ligand 1. These results suggest a novel role for P-selectin in regulating monocyte fate determination.

Mouse soluble CD14 truncated at amino acid 71 in transgenic mice: preventive effect on endotoxin-mediated toxic shock

Mouse soluble CD14 truncated at amino acid 71 (N71) contains the lipopolysaccharide (LPS)-binding sequence. Transgenic mice carrying alpha1-antitrypsin (AT) promoter-N71 fusion genes, designated AT363-1 and AT363-2, were produced. These mice constitutively produced elevated levels of N71. The concentration of LPS in sera after intraperitoneal LPS injection was lower in AT363-1 mice than in nontransgenic mice. The expression of N71 mRNA was enhanced by subcutaneous turpentine oil injection. The levels of serum LPS and tumor necrosis factor-alpha (TNF-alpha) after intraperitoneal LPS injections were lower in AT363-1 mice than in nontransgenic mice. Cell surface TNF-alpha and CD14 expression in exudate peritoneal macrophages prepared by intraperitoneal injection of proteose peptone and then LPS were higher in AT363-1 mice than in nontransgenic mice. Neutrophil infiltration in the liver after induction of the generalized Shwartzman reaction was lower in AT363-1 mice than in nontransgenic mice. Lethality of the Shwartzman reaction was significantly lower in AT363-1 than in nontransgenic mice. These findings suggest that the endotoxin-binding protein (N71) from CD14 prevents endotoxin-mediated toxic shock.

Plasmacytoid dendritic cell-derived IFN-alpha induces TNF-related apoptosis-inducing ligand/Apo-2L-mediated antitumor activity by human monocytes following CpG oligodeoxynucleotide stimulation

Immunostimulatory oligodeoxynucleotides (ODN) containing the CpG motif are being tested as immune adjuvants in many disease settings. Of the human PBMC examined, plasmacytoid dendritic cells (pDC) are a major source of type I IFN upon stimulation with CpG ODN. IFNs have numerous immunostimulatory effects, including the induction of TNF-related apoptosis-inducing ligand (TRAIL)/Apo-2L on monocytes, NK cells, and T cells. Importantly, IFN has also been linked to antitumor responses. Thus, we tested whether CpG ODN stimulation of PBMC led to TRAIL/Apo-2L-induced tumor cell death. When PBMC were stimulated with CpG ODN, TRAIL/Apo-2L-dependent tumor cell death was observed. Further examination of CpG ODN-stimulated PBMC revealed that TRAIL/Apo-2L expression was limited to CD14(+) cells, which, when depleted, led to a loss of the TRAIL/Apo-2L-mediated tumor cell killing. Moreover, pDC depletion also abolished the TRAIL/Apo-2L-mediated killing of tumor cell targets. Analysis of the pDC showed IFN-alpha production after CpG ODN stimulation. Finally, inclusion of neutralizing IFN-alpha antiserum with the PBMC during CpG ODN stimulation abrogated TRAIL/Apo-2L-mediated tumor cell killing. These results define a mechanism by which CpG ODN induces TRAIL/Apo-2L-dependent killing of tumor cells by CD14(+) PBMC, in which CpG ODN-activated pDC produce IFN-alpha that stimulates CD14(+) PBMC to express functional TRAIL/Apo-2L.

Clinical-scale generation of dendritic cells in a closed system

Immunotherapy of malignant diseases based on dendritic cells (DCs) pulsed with tumor antigens is a promising approach. Therefore, there is a demand for large-scale, clinical-grade ex vivo generation of DCs. Here, a procedure is presented that combines monocyte selection and tissue culture in closed systems under current good manufacturing practice conditions. Leukocytes from three patients with urologic cancers were collected by leukapheresis and subjected to immunomagnetic enrichment. From leukapheresis products containing 1.6 +/- 0.2 x 1010 (mean +/- SEM) leukocytes with a frequency of CD14+ monocytes of 18.7 +/- 2.3%, monocytes were enriched to 94.3 +/- 2.2%. CD14+ cell recovery was 67.0 +/- 4.7%. After 6 days of culture in Teflon bags in X-Vivo 15 medium supplemented with autologous plasma, GM-CSF, and IL-4, cells showed an immature DC phenotype and efficient antigen uptake. Following an additional 3 days of culture in the presence of GM-CSF, IL-4, IL-1beta, IL-6, TNFalpha, and PGE(2), cells (82.0 +/- 5.8% CD83+) displayed a mature DC morphology and phenotype, including expression of CD11b, CD11c, CD18, CD25, CD40, CD54, CD58, CD80, CD86, HLA class I, and HLA-DR as well as expression of CCR7 but not CCR5. The mature DC phenotype remained stable for at least 5 days in the absence of cytokines. Yield of DC was 14.0 +/- 4.7% and viability was 91.9 +/- 3.5%. Mature DCs effectively clustered with naive T cells and potently induced allogeneic T-cell proliferation and IL-2 and IFNgamma but not IL-4 production. Thus, this procedure allows large-scale generation of stably mature, Th1 responses inducing DCs under cGMP conditions in a closed system from cancer patients and is therefore well suited for immunotherapy.

DNA microarray analysis of human gingival fibroblasts from healthy and inflammatory gingival tissues

In the inflammatory gingival tissues of patients with periodontitis, cytokines such as interleukin (IL)-1 alpha, IL-1 beta, IL-6, IL-8, and tumor necrosis factor (TNF)-alpha have been detected. Gingival fibroblasts are the major constituents of gingival tissue. We recently demonstrated that lipopolysaccharide (LPS) from periodontopathic bacteria induces inflammatory reactions in various tissues via CD14 and/or Toll-like receptors (TLRs) in gingival tissues [Biochem. Biophys. Res. Commun. 273 (2000) 1161]. To confirm this, we examined the expression of IL-1 alpha, IL-1 beta, IL-6, IL-8, TNF-alpha, CD14, TLR2, and TLR4 in human gingival fibroblasts (HGFs) obtained from patients with healthy or inflammatory gingiva using DNA microarray analysis. We also studied the expression levels of these proteins by flow cytometric analysis (FACS). The expression levels of all eight genes in the HGFs of the Inflammatory group were significantly higher than those in the Healthy group on DNA microarray analysis. FACS revealed that the expression levels of all eight proteins on the HGFs of the Inflammatory group were higher than those on the Healthy group. Our data indicated that these eight proteins in HGFs are involved in inflammatory conditions in the gingiva, including periodontal disease. Our results suggested that these eight proteins, in turn, act directly or indirectly on the immune response by activating host cells involved in inflammatory processes.

Resistance to phorbol 12-myristate 13-acetate-induced cell growth arrest in an HL60 cell line chronically exposed to a glutathione S-transferase pi inhibitor

Glutathione S-transferase pi (GSTpi; EC 2.5.1.18) has been shown recently to be a regulator of mitogen-activated protein kinases (MAPK). We have developed, by chronic exposure of HL60 cells to increasing concentrations of a peptidomimetic GSTpi inhibitor TLK199, a 10-fold resistant cell line (HL60/TLK199). Among the cellular adaptations observed in this cell line was an increase in extracellular signal-regulated kinase (ERK) activity without modification of basal expression levels. Phorbol 12-myristate 13-acetate (PMA) induced monocyte/macrophage cytodifferentiation in both HL60 wild-type (WT) and HL60/TLK199 cells. In contrast, PMA induced a pronounced cell growth inhibition and G(0)/G(1) cell cycle arrest in HL60 WT cells, while this differentiating agent had only a mild effect on cell growth without G(0)/G(1) cell cycle arrest in HL60/TLK199. This effect was associated with a rapid and sustained activation of ERK (up to 6hr) in HL60 WT cells but only a transient induction of these kinases (between 30 and 60min) in HL60/TLK199. Furthermore, treatment of both cell lines with PMA in combination with the protein tyrosine phosphatase inhibitors sodium orthovanadate (OV) or 3,4-dephostatin (DPN) circumvented the resistance to cell growth arrest and potentiated differentiation in HL60/TLK199 but had no effect on HL60 WT cells. The circumvention of the resistance to PMA was associated with a sustained activation of ERK. These data suggest that chronic exposure of HL60 cells to TLK199 alters cellular ERK activation by PMA, which may contribute to the differential response of the WT and resistant cells to PMA.

iC3b arrests monocytic cell differentiation into CD1c-expressing dendritic cell precursors: a mechanism for transiently decreased dendritic cells in vivo after human skin injury by ultraviolet B

Our previous data indicated that C3, its bioactive product iC3b, and the iC3b ligand CD11b are critical for ultraviolet-induced immunosuppression. We thus hypothesized that iC3b is an important skin-based factor regulating CD11b+ monocytic cell function in the acute post-ultraviolet period. Although monocytic cell migration peaked at 1-3 d after ultraviolet exposure of skin, dermal CD1c dendritic cells underwent a rapid and prolonged depletion that did not recover until day 7. Because ultraviolet-induced iC3b deposits are reciprocally maximal on day 3, but fade by day 7, we next hypothesized that iC3b can be responsible for the delay in differentiation into dendritic cells of monocytic cells migrating into ultraviolet-exposed skin. Analysis of dermal cells derived from keratome biopsies suggested that iC3b exposure could inhibit the development of CD1c+ dermal cells. To model newly immigrating blood monocytes entering ultraviolet-exposed, iC3b-containing dermis, purified monocytes from human blood were induced with granulocyte-macrophage colony stimulating factor to generate a population of dendritic cell precursors expressing CD1c. Incubation with iC3b markedly inhibited the appearance of CD1c+ cells (p<0.05) and induced CD1c-CD14+ cells. This inhibition was reversed by coincubation with an anti-CD11b antibody that blocks the iC3b binding site. Other functions associated with dendritic cell maturation were also inhibited by iC3b, such as interleukin-12p70 production as well as CD80 and CD40 expression. Restimulation of monocytes for DC maturation revealed that iC3b induced a temporary inhibition of DC differentiation. Thus, a human skin response in which iC3b is transiently (3-7 d) generated in dermis, such as ultraviolet, can arrest monocytic skin-infiltrating cells from undergoing dendritic cell precursor differentiation.

Inhibition of IFN-gamma signaling by glucocorticoids

Recent reports suggest that a novel mechanism of glucocorticoid (GC) immunosuppressive action is inhibition of signaling by IL-2 and IL-12, cytokines that use the Janus kinase-STAT signaling pathway. We investigated whether GCs could also block activation of Janus kinase-STAT signaling by IFN-gamma, a potent proinflammatory cytokine. Addition of dexamethasone to PBMC cultures resulted in a dramatic inhibition of IFN-gamma activation of STAT1. Several days of exposure to GCs were required for inhibition of IFN-gamma signaling to become apparent, and the underlying mechanism was down-regulation of STAT1 expression. GCs suppressed the expression of STAT1 mRNA, but did not affect STAT1 protein stability. STAT1 expression and IFN-gamma signaling were preferentially suppressed in macrophages. GCs did not act directly on macrophages, but worked indirectly by regulating macrophage-lymphocyte interactions that control STAT1 expression. GCs inhibited IFN-gamma-inducible gene expression, thus demonstrating the physiological significance of inhibition of signal transduction. Our results identify a novel level of regulation of IFN-gamma signaling, whereby GCs control the amplitude of IFN-gamma signaling by regulating STAT1 expression. These results suggest that inhibition of IFN-gamma signaling contributes to the immunosuppressive action of GCs.

A novel myeloid-like NK cell progenitor in human umbilical cord blood

Natural killer (NK) cell differentiation from pluripotent CD34(+) human hematopoietic stem cells or oligopotent lymphoid progenitors has already been reported. In the present study, long-term cultures of the CD56(-)/CD34(-) myeloid-like adherent cell fraction (ACF) from umbilical cord blood (UCB), characterized by the expression of CD14(+) as well as other myeloid markers, were set up with flt3 ligand (FL) and interleukin-15 (IL-15). The UCB/ACF gradually expressed the CD56 marker, which reached fairly high levels (approximately 90% of the cells were CD56(+)) by day 15. FL plus IL-15-driven ACF/CD56(+) cells progressively expressed a mature NK functional program lysing both NK- and lymphokine-activate killer (LAK)-sensitive tumor targets and producing high levels of interferon-gamma (IFN-gamma), granulocyte-macrophage colony-stimulating factor, tumor necrosis factor alpha, and IL-10 upon stimulation with IL-12 and IL-18. Similar results were obtained when highly purified CD14(+) cells from UCB were cultured with FL and IL-15. In contrast, UCB/CD34(+) cells cultured under the same conditions showed a delayed expression of CD56 and behaved functionally differently in that they exhibited NK but not LAK cytotoxicity and produced significantly fewer cytokines. Kinetic studies on the phenotype of UCB/ACF or UCB/CD14(+) cells cultured in the presence of FL and IL-15 showed a rapid decrease in CD14 expression after day 5, which reached levels of zero by day 20. Approximately 60% of the CD56(+) derived from the UCB/ACF or the UCB/CD14(+) cells coexpressed CD14 by day 5. Taken together, our data support the role of CD14(+) myeloid-like cells within UCB as a novel progenitor for lymphoid NK cells.

Modulation of human beta-defensin-2 transcription in pulmonary epithelial cells by lipopolysaccharide-stimulated mononuclear phagocytes via proinflammatory cytokine production

Human beta-defensin (hBD)-2, a cationic antimicrobial peptide primarily induced in epithelial cells in response to inflammatory stimuli, plays an important role in host defense. To elucidate the expression mechanism of hBD-2 in the lung, we investigated the modulation of hBD-2 transcription in pulmonary epithelial cells by mononuclear phagocytes stimulated with LPS. Coculture of A549 pulmonary epithelial cells with Mono-Mac-6 monocytic cells in the presence of Escherichia coli LPS markedly up-regulated hBD-2 promoter activity, whereas A549 alone did not respond to LPS to activate the hBD-2 promoter. Furthermore, IL-1beta and TNF-alpha in the culture supernatants from LPS-stimulated monocytic cells activated the hBD-2 promoter in A549 cells. Of note, IL-1beta was more potent than TNF-alpha in this effect. In addition, a mutation of the NF-kappaB site at -200 (pkappaB1 site) completely abolished this IL-1beta- and TNF-alpha-induced hBD-2 promoter activation, whereas NF-kappaB inhibitors (MG-132 and helenalin) strongly suppressed it. Moreover, electrophoretic mobility shift assay suggested that NF-kappaB, consisting of p65-p50 heterodimer, could bind to the pkappaB1 site in cytokine-stimulated A549 cells. Interestingly, flow cytometric analysis revealed that A549 cells expressed CD14 but lacked Toll-like receptor 4, which may account for the hyporesponsiveness of A549 cells to LPS. Taken together, these results suggest that hBD-2 expression in pulmonary epithelial cells is modulated by NF-kappaB via the actions of IL-1beta and TNF-alpha produced by LPS-stimulated mononuclear phagocytes.

Strategic compartmentalization of Toll-like receptor 4 in the mouse gut

Pattern recognition receptors (PRRs), which include the Toll-like receptors (TLRs), are involved in the innate immune response to infection. TLR4 is a model for the TLR family and is the main LPS receptor. We wanted to determine the expression of TLR4 and compare it with that of TLR2 and CD14 along the gastrointestinal mucosa of normal and colitic BALB/c mice. Colitis was induced with 2.5% dextran sodium sulfate (DSS). Mucosa from seven segments of the digestive tract (stomach, small intestine in three parts, and colon in three parts) was isolated by two different methods. Mucosal TLR4, CD14, TLR2, MyD88, and IL-1beta mRNA were semiquantified by Northern blotting. TLR4 protein was determined by Western blotting. TLR4/MD-2 complex and CD14 were evaluated by immunohistochemistry. PRR genes were constitutively expressed and were especially stronger in colon. TLR4 and CD14 mRNA were increased in the distal colon, but TLR2 mRNA was expressed more strongly in the proximal colon, and MyD88 had a uniform expression throughout the gut. Accordingly, TLR4 and CD14 protein levels were higher in the distal colon. TLR4/MD-2 and CD14 were localized at crypt bottom epithelial cells. TLR4/MD2, but not CD14, was found in mucosal mononuclear cells. Finally, DSS-induced inflammation was localized in the distal colon. All genes studied were up-regulated during DSS-induced inflammation, but the normal colon-stressed gut distribution was preserved. Our findings demonstrate that TLR4, CD14, and TLR2 are expressed in a compartmentalized manner in the mouse gut and provide novel information about the in vivo localization of PRRs.

Modulation of TNF-alpha expression in bone marrow macrophages: involvement of vitamin D response element

The calcium-regulating hormone, 1,25(OH)(2)D(3), induces tumor necrosis factor-alpha (TNF-alpha) synthesis and release from bone marrow macrophages (BMMs). To investigate the mechanism of this regulation, we have examined the effects of 1,25(OH)(2)D(3) on the cytokine message. 1,25(OH)(2)D(3) increased TNF-alpha mRNA abundance in a dose- and time-dependent manner. The combined treatment of BMMs with LPS and 1,25(OH)(2)D(3) resulted in a synergistic increase of TNF-alpha. The steroid also increased the expression of CD14 (LPS receptor). Vitamin D receptors (VDRs) mediate 1,25(OH)(2)D(3) genomic effects by forming homodimers or heterodimers with retinoic acid receptors (RARs) or retinoic X receptors (RXRs). The RXR ligand, 9-cis retinoic acid (9cRA), reduced TNF-alpha mRNA abundance in BMMs, but increased CD14 mRNA levels. 1,25(OH)(2)D(3) or LPS did not affect TNF-alpha transcript stability. 9cRA, however, caused TNF-alpha mRNA destabilization. Next, we searched for potential vitamin D response elements (VDREs) in the promoter region (1.2 kb) of the TNF-alpha gene, and identified six such sequences. Using electrophoresis mobility shift assay (EMSA) we identified one of those sequences (-1008 to -994) as a likely candidate to be a VDRE (tnfVDRE). The binding of tnfVDRE to BMM-derived nuclear extract was increased following cell treatment with 1,25(OH)(2)D(3). No induction was observed with 9cRA treatment, but the retinoid enhanced the activity of 1,25(OH)(2)D(3) when added together. Previously characterized VDREs (mouse osteopontin and rat osteocalcin) competed effectively with tnfVDRE, demonstrating the nature of the TNF-alpha-derived sequence as a VDRE. We observed super-shift and block-shift of the complex in the presence of either anti-VDR or anti-RXR antibodies. Our data suggest that 1,25(OH)(2)D(3) increases TNF-alpha transcript abundance in BMMs via a transcriptional mechanism; 9cRA decreases TNF-alpha mRNA by destabilizing the transcript, and possibly also by forming transcriptionally inactive complex with 1,25(OH)(2)D(3) on the tnfVDRE. The receptor complex interacting with tnfVDRE found in the promoter of the cytokine gene is probably composed of VDR-RXR heterodimer.

Lipopolysaccharide promotes the survival of osteoclasts via Toll-like receptor 4, but cytokine production of osteoclasts in response to lipopolysaccharide is different from that of macrophages

Lipopolysaccharide is a pathogen that causes inflammatory bone loss. Monocytes and macrophages produce proinflammatory cytokines such as IL-1, TNF-alpha, and IL-6 in response to LPS. We examined the effects of LPS on the function of osteoclasts formed in vitro in comparison with its effect on bone marrow macrophages, osteoclast precursors. Both osteoclasts and bone marrow macrophages expressed mRNA of Toll-like receptor 4 (TLR4) and CD14, components of the LPS receptor system. LPS induced rapid degradation of I-kappaB in osteoclasts, and stimulated the survival of osteoclasts. LPS failed to support the survival of osteoclasts derived from C3H/HeJ mice, which possess a missense mutation in the TLR4 gene. The LPS-promoted survival of osteoclasts was not mediated by any of the cytokines known to prolong the survival of osteoclasts, such as IL-1beta, TNF-alpha, and receptor activator of NF-kappaB ligand. LPS stimulated the production of proinflammatory cytokines such as IL-1beta, TNF-alpha, and IL-6 in bone marrow macrophages and peritoneal macrophages, but not in osteoclasts. These results indicate that osteoclasts respond to LPS through TLR4, but the characteristics of osteoclasts are quite different from those of their precursors, macrophages, in terms of proinflammatory cytokine production in response to LPS.