The proinflammatory CD14+CD16+DR++ monocytes are a major source of TNF

In human blood two monocyte populations can be distinguished, i.e., the CD14(++)CD16(-)DR(+) classical monocytes and the CD14(+)CD16(+)DR(++) proinflammatory monocytes that account for only 10% of all monocytes. We have studied TNF production in these two types of cells using three-color immunofluorescence and flow cytometry on whole peripheral blood samples stimulated with either LPS or with the bacterial lipopeptide S-(2,3-bis(palmitoyloxy)-(2-RS)-propyl)-N-palmitoyl-(R)-Cys-(S)-Ser-(S)-Lys(4)-OH,trihydrochloride (Pam3Cys). After stimulation with LPS the median fluorescence intensity for TNF protein was 3-fold higher in the proinflammatory monocytes when compared with the classical monocytes. After stimulation with Pam3Cys they almost exclusively responded showing 10-fold-higher levels of median fluorescence intensity for TNF protein. The median fluorescence intensity for Toll-like receptor 2 cell surface protein was found 2-fold higher on CD14(+)CD16(+)DR(++) monocytes, which may explain, in part, the higher Pam3Cys-induced TNF production by these cells. When analyzing secretion of TNF protein into the supernatant in PBMCs after depletion of CD16(+) monocytes we found a reduction of LPS-induced TNF by 28% but Pam3Cys-induced TNF was reduced by 64%. This indicates that the minor population of CD14(+)CD16(+) monocytes are major producers of TNF in human blood.

A Polymorphism* in the 5' flanking region of the CD14 gene is associated with circulating soluble CD14 levels and with total serum immunoglobulin E

Total serum immunoglobulin (Ig)E levels are genetically regulated, but the mechanism of inheritance is not well understood. Cytokines produced by T-helper (Th)1 and Th2 lymphocytes control IgE synthesis. Bacterial antigens may favor the development of Th1 cells from naive CD4-positive T cells through a CD14-dependent pathway. CD14 is constitutively expressed on the surface of monocytes and macrophages, and is also present in serum in a soluble form (sCD14). The CD14 gene maps to chromosome 5q31.1, a candidate region for loci regulating total serum IgE. We hypothesized that genetic variants in the CD14 gene could influence Th-cell differentiation and thus total serum IgE. We identified a C-to-T transition at base pair -159 from the major transcription start site (CD14/-159). Among 481 children recruited from a general population sample, frequency of allele C was 51.4%. TT homozygotes had significantly higher sCD14 levels than did carriers of both the CC and CT genotypes (P = 0.01). TT homozygotes also had significantly lower levels of IgE than did carriers of the other two genotypes, but differences were significant only among children who were skin test-positive to local aeroallergens (P = 0.004). There was no association between CD14/-159 and either interleukin (IL)-4 or interferon (IFN)-gamma responses by peripheral blood mononuclear cells. However, IFN-gamma and IL-4 responses were positively and negatively correlated, respectively, with serum sCD14 levels. We conclude that CD14/-159 plays a significant role in regulating serum sCD14 levels and total serum IgE levels.

Plasma cytokine parameters and mortality in patients with chronic heart failure

BACKGROUND

Inflammatory immune activation is an important feature in chronic heart failure (CHF). Little is known about the prognostic importance of tumor necrosis factor-alpha (TNF-alpha), soluble TNF-receptor 1 and 2 (sTNF-R1/sTNF-R2), interleukin-6 (IL-6), and soluble CD14 receptors (sCD14) in CHF patients.

METHODS AND RESULTS

In 152 CHF patients (age 61+/-1 years, New York Heart Association [NYHA] class 2.6+/-0.1, peak VO(2) 17.3+/-0.6 mL. kg(-1). min(-1), mean+/-SEM) plasma concentrations of immune variables were prospectively assessed. During a mean follow-up of 34 months (>12 months in all patients), 62 patients (41%) died. Cumulative mortality was 28% at 24 months. In univariate analyses, increased total and trimeric TNF-alpha, sTNF-R1, and sTNF-R2 (all P</=0.0001), sCD14 (P=0.0007), and IL-6 (P=0.005) predicted 24-month mortality. With multivariate analysis and receiver operating characteristics, sTNF-R1 emerged among all cytokine parameters as the strongest and most accurate prognosticator in this CHF population, regardless of follow-up duration and independently of NYHA class, peak VO(2), VE/VCO(2) slope, left ventricular ejection fraction, and wasting (P<0.001). The receiver operating characteristic area under the curve for sTNF-R1 was greater than for sTNF-R2 at 6, 12, and 18 months (all P<0.05).

CONCLUSIONS

sTNF-R1 was the strongest and most accurate prognosticator, independent of established markers of CHF severity. Assessment of sTNF-R1 may be useful in identifying patients who are at high risk of death and in monitoring patients undergoing anti-TNF-alpha treatment.

Accumulation of tissue factor into developing thrombi in vivo is dependent upon microparticle P-selectin glycoprotein ligand 1 and platelet P-selectin

Using a laser-induced endothelial injury model, we examined thrombus formation in the microcirculation of wild-type and genetically altered mice by real-time in vivo microscopy to analyze this complex physiologic process in a system that includes the vessel wall, the presence of flowing blood, and the absence of anticoagulants. We observe P-selectin expression, tissue factor accumulation, and fibrin generation after platelet localization in the developing thrombus in arterioles of wild-type mice. However, mice lacking P-selectin glycoprotein ligand 1 (PSGL-1) or P-selectin, or wild-type mice infused with blocking P-selectin antibodies, developed platelet thrombi containing minimal tissue factor and fibrin. To explore the delivery of tissue factor into a developing thrombus, we identified monocyte-derived microparticles in human platelet-poor plasma that express tissue factor, PSGL-1, and CD14. Fluorescently labeled mouse microparticles infused into a recipient mouse localized within the developing thrombus, indicating that one pathway for the initiation of blood coagulation in vivo involves the accumulation of tissue factor- and PSGL-1-containing microparticles in the platelet thrombus expressing P-selectin. These monocyte-derived microparticles bind to activated platelets in an interaction mediated by platelet P-selectin and microparticle PSGL-1. We propose that PSGL-1 plays a role in blood coagulation in addition to its known role in leukocyte trafficking.

Increased lipopolysaccharide binding protein in cirrhotic patients with marked immune and hemodynamic derangement

Intestinal bacterial overgrowth and translocation, both common in cirrhosis with ascites, may lead to the activation of monocytes and lymphocytes, increased levels of proinflammatory cytokines, and enhanced synthesis of nitric oxide present in cirrhosis. Bacterial endotoxin promotes the synthesis of lipopolysaccharide (LPS)-binding protein (LBP), and forms a LPS-LBP complex that binds to CD14. This study was designed to evaluate LBP levels and their correlation to the immune response and the hemodynamic status in cirrhotic patients. Plasma LBP, endotoxin, soluble CD14 (sCD14), cytokines, renin, nitrites, and systemic vascular resistance were determined before and 4 weeks after norfloxacin or placebo in 102 cirrhotic patients and 30 controls. LBP was elevated in 42% of ascitic cirrhotic patients (15.7 +/- 0.7 versus 6.06 +/- 0.5 microg/mL, P <.01). In 60% of high LBP patients, endotoxin was within normal range. Among ascitic patients, those with high LBP showed greater (P <.05) levels of sCD14, tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), nitrites + nitrates (NOx)/creatinine, and renin, and lower vascular resistance. In the cirrhotic patients with high LBP, norfloxacin normalized (P <.01) LBP (from 16.6 +/- 0.5 to 5.82 +/- 0.8 microg/mL) and sCD14; reduced the level of cytokines, NOx/creatinine, and renin; and increased vascular resistance; but lacked effect in patients with normal LBP. Portal pressure was unchanged after norfloxacin in another group of 18 cirrhotic patients with high and 19 with normal LBP. In conclusion, the subset of ascitic cirrhotic patients with marked immune and hemodynamic derangement is identified by increased LBP levels. Amelioration of these abnormalities by norfloxacin suggests the involvement of enteric bacteria or their products in the triggering of the process.

Gene expression profiling of human decidual macrophages: evidence for immunosuppressive phenotype

Background

Although uterine macrophages are thought to play an important regulatory role at the maternal-fetal interface, their global gene expression profile is not known.

Methodology/Principal Findings

Using micro-array comprising approximately 14,000 genes, the gene expression pattern of human first trimester decidual CD14+ monocytes/macrophages was characterized and compared with the expression profile of the corresponding cells in blood. Some of the key findings were confirmed by real time PCR or by secreted protein. A unique gene expression pattern intrinsic of first trimester decidual CD14+ cells was demonstrated. A large number of regulated genes were functionally related to immunomodulation and tissue remodelling, corroborating polarization patterns of differentiated macrophages mainly of the alternatively activated M2 phenotype. These include known M2 markers such as CCL-18, CD209, insulin-like growth factor (IGF)-1, mannose receptor c type (MRC)-1 and fibronectin-1. Further, the selective up-regulation of triggering receptor expressed on myeloid cells (TREM)-2, alpha-2-macroglobulin (A2M) and prostaglandin D2 synthase (PGDS) provides new insights into the regulatory function of decidual macrophages in pregnancy that may have implications in pregnancy complications.

Conclusions/Significance

The molecular characterization of decidual macrophages presents a unique transcriptional profile replete with important components for fetal immunoprotection and provides several clues for further studies of these cells.

Differential chemokine receptor expression and function in human monocyte subpopulations

The subset of human blood monocytes expressing low levels of CD14 and high levels of CD16 (CD14+CD16+) exhibits features resembling mature tissue macrophages and can be expanded in inflammatory conditions. We analyzed expression of CC chemokine receptors (CCR) in CD14+CD16+ versus CD14++ monocytes, which may be crucial for specific trafficking. Multicolor flow cytometric analysis of whole peripheral blood revealed that, as opposed to CD14++ monocytes, the CD14+CD16+ subset lacked surface expression of monocyte chemotactic protein-1 (MCP-1) receptor CCR2, however, it showed significantly higher surface expression of the macrophage inflammatory protein 1alpha (MIP-1alpha)/RANTES receptor CCR5. This was paralleled by differences in mRNA expression in the subsets, as shown by reverse transcriptase-polymerase chain reaction using sorted cells. In comparison to CD14++ monocytes, CD14+CD16+ cells expressed lower CCR2 but higher CCR5 transcript levels, whereas CCR1 levels were equivalent. Flow cytometric analysis of isolated human monocytes recovered after transendothelial chemotaxis assays revealed that the percentage of CD14+CD16+ cells was dramatically reduced in the fraction migrating toward MCP-1 compared with the fraction that did not migrate or the input, showing that polarized CCR2 expression was accompanied by a differential chemotactic responsiveness. Moreover, CD11b surface expression was preferentially up-regulated by MCP-1 in CD14++ cells but by MIP-1alpha in CD14+CD16+ monocytes, confirming the functional relevance of distinct CCR expression. The characteristics of CD14+CD16+ cells may reflect preactivation by cytokines and determine their predilective localization during specific inflammatory conditions or susceptibility to infection.

Elevated soluble CD14 receptors and altered cytokines in chronic heart failure

We hypothesized that in patients with chronic heart failure mesenteric venous congestion leads to increased bowel permeability, bacterial translocation, and thereby endotoxin release; the increased endotoxin challenge then causes immune activation with increased soluble CD14 levels and tumor necrosis factor (TNF)-alpha production. Patients with high soluble CD14 levels (indicative of endotoxin-cell interaction) have markedly increased plasma levels of TNF-alpha, soluble TNF receptors 1 and 2, and intracellular adhesion molecule-1, supporting this hypothesis.

Clinical recovery from surgery correlates with single-cell immune signatures

Delayed recovery from surgery causes personal suffering and substantial societal and economic costs. Whether immune mechanisms determine recovery after surgical trauma remains ill-defined. Single-cell mass cytometry was applied to serial whole-blood samples from 32 patients undergoing hip replacement to comprehensively characterize the phenotypic and functional immune response to surgical trauma. The simultaneous analysis of 14,000 phosphorylation events in precisely phenotyped immune cell subsets revealed uniform signaling responses among patients, demarcating a surgical immune signature. When regressed against clinical parameters of surgical recovery, including functional impairment and pain, strong correlations were found with STAT3 (signal transducer and activator of transcription), CREB (adenosine 3',5'-monophosphate response element-binding protein), and NF-κB (nuclear factor κB) signaling responses in subsets of CD14(+) monocytes (R = 0.7 to 0.8, false discovery rate <0.01). These sentinel results demonstrate the capacity of mass cytometry to survey the human immune system in a relevant clinical context. The mechanistically derived immune correlates point to diagnostic signatures, and potential therapeutic targets, that could postoperatively improve patient recovery.

Soluble forms of Toll-like receptor (TLR)2 capable of modulating TLR2 signaling are present in human plasma and breast milk

Dysregulation of the initial, innate immune response to bacterial infection may lead to septic shock and death. Toll-like receptors (TLRs) play a crucial role in this innate immune response, and yet the regulatory mechanisms controlling microbial-induced TLR triggering are still to be fully understood. We have therefore sought specific regulatory mechanisms that may modulate TLR signaling. In this study, we tested for the possible existence of a functionally active soluble form of TLR2. We demonstrated the existence of natural soluble forms of TLR2 (sTLR2), which we show to be capable of modulating cell activation. We found that blood monocytes released sTLR2 constitutively and that the kinetics of sTLR2 release increased upon cell activation. Analysis of cells expressing the human TLR2 cDNA or its c-myc-tagged version indicated that sTLR2 resulted from the posttranslational modification of the TLR2 protein in an intracellular compartment. Moreover, an intracellular pool of sTLR2 is maintained. sTLR2 was found naturally expressed in breast milk and plasma. Milk sTLR2 levels mirrored those of the TLR coreceptor soluble CD14. Depletion of sTLR2 from serum resulted in an increased cellular response to bacterial lipopeptide. Notably, serum sTLR2 was lower in tuberculosis patients. Coimmunoprecipitation experiments and computational molecular docking studies showed an interaction between sTLR2 and soluble CD14 in plasma and milk. These findings suggest the existence of a novel and specific innate immune mechanism regulating microbial-induced TLR triggering, and may lead to new therapeutics for the prevention and/or treatment of severe infectious diseases.

Host response to translocated microbial products predicts outcomes of patients with HBV or HCV infection

BACKGROUND & AIMS

Chronic infection with hepatitis B or C virus (HBV or HCV) is a leading cause of cirrhosis by unknown mechanisms of pathogenesis. Translocation of gut microbial products into the systemic circulation might increase because of increased intestinal permeability, bacterial overgrowth, or impaired clearance of microbial products by Kupffer cells. We investigated whether the extent and progression of liver disease in patients with chronic HBV or HCV infection are associated with microbial translocation and subsequent activation of monocytes.

METHODS

In a retrospective study, we analyzed data from 16 patients with minimal fibrosis, 68 with cirrhosis, and 67 uninfected volunteers. We analyzed plasma levels of soluble CD14 (sCD14), intestinal fatty acid binding protein, and interleukin-6 by enzyme-linked immunosorbent assay, and lipopolysaccharide (LPS) by the limulus amebocyte lysate assay, at presentation and after antiviral treatment.

RESULTS

Compared with uninfected individuals, HCV- and HBV-infected individuals had higher plasma levels of LPS, intestinal fatty acid binding protein (indicating enterocyte death), sCD14 (produced upon LPS activation of monocytes), and interleukin-6. Portal hypertension, indicated by low platelet counts, was associated with enterocyte death (P=.045 at presentation, P<.0001 after therapy). Levels of sCD14 correlated with markers of hepatic inflammation (P=.02 for aspartate aminotransferase, P=.002 for ferritin) and fibrosis (P<.0001 for γ-glutamyl transpeptidase, P=.01 for alkaline phosphatase, P<.0001 for α-fetoprotein). Compared to subjects with minimal fibrosis, subjects with severe fibrosis at presentation had higher plasma levels of sCD14 (P=.01) and more hepatic CD14+ cells (P=.0002); each increased risk for disease progression (P=.0009 and P=.005, respectively).

CONCLUSIONS

LPS-induced local and systemic inflammation is associated with cirrhosis and predicts progression to end-stage liver disease in patients with HBV or HCV infection.

CD14+,CD16+ blood monocytes and joint inflammation in rheumatoid arthritis

OBJECTIVE

CD14+,CD16+ monocytes, identified as a minor population of monocytes in human peripheral blood (PB), have been implicated in several inflammatory diseases. We undertook this study to investigate the relevance of this phenotype to joint inflammation in rheumatoid arthritis (RA).

METHODS

The expression of CD14, CD16, CC chemokine receptor 1 (CCR1), CCR5, and intercellular adhesion molecule 1 (ICAM-1) on monocytes was measured by flow cytometric analysis. Concentrations of the cytokines known to induce CD16 (including transforming growth factor beta1 [TGFbeta1], macrophage colony-stimulating factor [M-CSF], and interleukin-10 [IL-10]) and concentrations of the soluble form of CD14 (sCD14) in plasma and synovial fluid (SF) samples were measured by enzyme-linked immunosorbent assay. The induction of CD16 on RA blood monocytes cultured for 18 hours with 1 or with all 3 cytokines was determined.

RESULTS

The mean +/- SD frequency of CD14+,CD16+ blood monocytes was significantly increased in RA patients (11.7 +/- 5.6%; n = 105) compared with healthy controls (9.5 +/- 2.2%; n = 15) (P < 0.01), and the patient group with an increased frequency of CD16+ monocytes (> or =13.9%) had active disease, as defined by increased counts of tender and swollen joints, levels of acute-phase reactants, and titers of rheumatoid factor. The response to drug therapy correlated with changes in the frequency of this phenotype. The expression of CD16 on SF monocytes from RA patients was markedly elevated compared with the expression on PB monocytes. CD16 expression on RA blood monocytes was augmented in vitro by IL-10, M-CSF, and TGFbeta1. Plasma concentrations of these cytokines and of sCD14 were significantly higher in RA patients with high CD16+ monocyte frequencies than in those with low CD16+ monocyte frequencies or in healthy controls. CD14+,CD16+ monocytes expressed higher levels of CCR1, CCR5, and ICAM-1 than did regular CD14++,CD16- monocytes, particularly in active RA.

CONCLUSION

These results indicate that the maturation of blood monocytes into tissue-infiltrative CD16+ cells before entry into the joint, induced by cytokine spillover from the inflamed joint, may contribute to the persistent joint inflammation of RA.

Human circulating CD14+ monocytes as a source of progenitors that exhibit mesenchymal cell differentiation

Circulating CD14+ monocytes are precursors of phagocytes, such as macrophages and dendritic cells. Here we report primitive cells with a fibroblast-like morphology derived from human peripheral blood CD14+ monocytes that can differentiate into several distinct mesenchymal cell lineages. We named this cell population monocyte-derived mesenchymal progenitor (MOMP). MOMPs were obtained in vitro from human peripheral blood mononuclear cells cultured on fibronectin in the presence of fetal bovine serum alone as a source of growth factors. MOMPs had a unique molecular phenotype-CD14+CD45+CD34+type I collagen+-and showed mixed morphologic and molecular features of monocytes and endothelial and mesenchymal cells. MOMPs were found to be derived from a subset of circulating CD14+ monocytes, and their differentiation required that they bind fibronectin and be exposed to one or more soluble factors derived from peripheral blood CD14- cells. MOMPs could be expanded in culture without losing their original phenotype for up to five passages. The induction of MOMPs to differentiate along multiple limb-bud mesodermal lineages resulted in the expression of genes and proteins specific for osteoblasts, skeletal myoblasts, chondrocytes, and adipocytes. Our findings represent the first evidence that human circulating CD14+ monocytes are a source of progenitors that exhibit mesenchymal cell differentiation.

Expression of CD14 and Toll-like receptor 2 in farmers' and non-farmers' children

Children of farmers are at decreased risk of developing allergies. Results of epidemiological studies suggest increased exposure to microbial compounds might be responsible for this reduced risk. Alterations in adaptive immune response are thought to be the underlying mechanism. We measured expression of receptors for microbial compounds known to trigger the innate immune response. We showed that blood cells from farmers' children express significantly higher amounts of CD14 (0.96 vs 0.43, p=0.0013), and Toll-like receptor 2 (0.11 vs 0.04, p<0.0001) than those from non-farmers' children. We propose that the innate immune system responds to the microbial burden in the environment and modulates the development of allergic disease.

Circulating monocytes from systemic sclerosis patients with interstitial lung disease show an enhanced profibrotic phenotype

Profibrotic cells derived from circulating CD14+ monocytes include fibrocytes and alternatively activated macrophages. These cells are associated with interstitial lung disease (ILD) and are implicated in the pathogenesis of systemic sclerosis (SSc); however, the simultaneous presence of profibrotic cells and their associated mediators in the circulation of these patients has not been defined. We hypothesized that monocytes from patients with SSc-related ILD (SSc-ILD) would show profibrotic characteristics when compared with normal controls. We recruited patients with SSc-ILD (n=12) and normal controls (n=27) and quantified circulating collagen-producing cells by flow cytometry for CD45 and pro-collagen I. The in vitro activation potential of CD14+ monocytes in response to lipopolysaccharide was assessed using flow cytometry for CD163, and by ELISA for CCL18 and IL-10 secretion. Profibrotic mediators in plasma were quantified using Luminex-based assays. The concentration of circulating collagen-producing cells was increased in the SSc-ILD patients when compared with controls. These cells were composed of both CD34+ fibrocytes and a population of CD34+CD14+ cells. Cultured CD14+ monocytes from SSc-ILD patients revealed a profibrotic phenotype characterized by expression of CD163 and by enhanced secretion of CCL18 and IL-10 in response to proinflammatory activation. Plasma levels of IL-10, MCP-1, IL-1RA, and TNF levels were significantly elevated in the plasma of the SSc-ILD cohort. Subgroup analysis of the normal controls revealed that unlike the subjects < or =35 years, subjects > or =60 years old showed higher levels of circulating CD34+CD14+ cells, collagen-producing CD14+ monocytes, CD163+ monocytes, IL-4, IL-10, IL-13, MCP-1, and CCL18. These data indicate that the blood of patients with SSc-ILD and of healthy aged controls is enriched for fibrocytes, profibrotic monocytes, and fibrosis-associated mediators. Investigations defining the factors responsible for this peripheral blood profile may provide new insight into SSc-ILD as well as the pathophysiology of aging.

CD14 is an acute-phase protein

The origin of soluble CD14 (sCD14) in the circulation is uncertain. To examine whether CD14 could be an acute-phase protein (APP), the levels of sCD14, IL-6, and C-reactive protein were determined by ELISA in serum and synovial fluid (SF) of patients with various arthropathies, and the regulation of CD14 synthesis was examined in liver cells. In patients with crystal-mediated or immunologically mediated arthritis (rheumatoid arthritis), serum levels of sCD14 were higher than or similar to those found in infection-mediated arthritis (reactive arthritis), precluding a relation with bacteria exposure. Levels of sCD14 were similar in SF and serum, and did not correlate with the number of SF leukocytes, excluding an important source from leukocyte membrane-bound CD14, by protease-mediated shedding. In contrast, serum levels of sCD14 in patients correlated with those of C-reactive protein, a classical APP, and IL-6, a cytokine known to regulate the synthesis of APP in the liver. Serum levels of sCD14 also correlated with disease activity in rheumatoid arthritis and reactive arthritis patients. IL-6 stimulated the production of CD14 by HepG2 hepatoma cells. By real-time PCR, the inducibility of CD14 by IL-6 was also observed at the mRNA level both in HepG2 cells and human primary hepatocytes. These in vitro results were confirmed by in vivo studies in IL-6(-/-) mice injected with turpentine, an experimental model of acute-phase response. Liver levels of CD14 mRNA increased in IL-6(+/+), but not in IL-6(-/-) mice. These results indicate that sCD14 can be considered as a type 2 APP.

Evaluation of a newly identified soluble CD14 subtype as a marker for sepsis

CD14, a high-affinity receptor for lipopolysaccharide (LPS), is a glycoprotein expressed on the surface membranes of monocytes/macrophages. We have identified a previously unknown form of soluble CD14, named soluble CD14 subtype (sCD14-ST), that is increased in patients with sepsis. To measure sCD14-ST concentrations in plasma, we prepared anti-sCD14-ST antibodies and developed an enzyme immunoassay (EIA) for this soluble form of CD14. With this assay, quantitative measurements are available within 4 h, and we compared the levels of sCD14-ST in plasma from normal subjects (healthy controls), patients with systemic inflammatory response syndrome (SIRS), and sepsis patients. The level of sCD14-ST in subjects with sepsis was much higher than the levels in subjects with SIRS and the healthy controls. Additionally, when a subject's sCD14-ST level was used as a diagnostic marker for sepsis, the area under the receiver operating characteristic (ROC) curve was 0.817, thereby demonstrating that elevated sCD14-ST levels were a better marker for sepsis than the other molecular markers we tested. sCD14-ST levels also correlated with procalcitonin (PCT) levels and with sequential organ failure assessment (SOFA) scores. Finally, changes in sCD14-ST concentration correlated with the severity of sepsis. Taken together, these results indicate that sCD14-ST is a useful marker for the rapid diagnosis of sepsis and for monitoring the severity of the disease.

Does an index composed of clinical data reflect effects of inflammation, coagulation, and monocyte activation on mortality among those aging with HIV?

BACKGROUND

When added to age, CD4 count and human immunodeficiency virus type 1 (HIV-1) RNA alone (Restricted Index), hemoglobin, FIB-4 Index, hepatitis C virus (HCV), and estimated glomerular filtration rate improve prediction of mortality. Weighted and combined, these 7 routine clinical variables constitute the Veterans Aging Cohort Study (VACS) Index. Because nonroutine biomarkers of inflammation (interleukin 6 [IL-6]), coagulation (D-dimer), and monocyte activation (sCD14) also predict mortality, we test the association of these indices and biomarkers with each other and with mortality.

METHODS

Samples from 1302 HIV-infected veterans on antiretroviral therapy were analyzed. Indices were calculated closest to date of collection. We calculated Spearman correlations stratified by HIV-1 RNA and HCV status and measured association with mortality using C statistics and net reclassification improvement (NRI).

RESULTS

Of 1302 subjects, 915 had HIV-1 RNA <500 copies/mL and 154 died. The VACS Index was more correlated with IL-6, D-dimer, and sCD14 than the Restricted Index (P < .001). It was also more predictive of mortality (C statistic, 0.76; 95% confidence interval [CI], .72-.80) than any biomarker (C statistic, 0.66-0.70) or the Restricted Index (C statistic, 0.71; 95% CI, .67-.75). Compared to the Restricted Index alone, NRI resulted from incremental addition of VACS Index components (10%), D-dimer (7%), and sCD14 (4%), but not from IL-6 (0%).

CONCLUSIONS

Among HIV-infected individuals, independent of CD4, HIV-1 RNA, and age, hemoglobin and markers of liver and renal injury are associated with inflammation. Addition of D-dimer and sCD14, but not IL-6, improves the predictive accuracy of the VACS Index for mortality.

Innate recognition of bacteria in human milk is mediated by a milk-derived highly expressed pattern recognition receptor, soluble CD14

Little is known about innate immunity to bacteria after birth in the hitherto sterile fetal intestine. Breast-feeding has long been associated with a lower incidence of gastrointestinal infections and inflammatory and allergic diseases. We found in human breast milk a 48-kD polypeptide, which we confirmed by mass spectrometry and sequencing to be a soluble form of the bacterial pattern recognition receptor CD14 (sCD14). Milk sCD14 (m-sCD14) concentrations were up to 20-fold higher than serum sCD14 from nonpregnant, pregnant, or lactating women. In contrast, lipopolysaccharide (LPS)-binding protein was at very low levels. Mammary epithelial cells produced 48-kD sCD14. m-sCD14 mediated activation by LPS and whole bacteria of CD14 negative cells, including intestinal epithelial cells, resulting in release of innate immune response molecules. m-sCD14 was undetectable in the infant formulas and commercial (cows') milk tested, although it was present in bovine colostrum. These findings indicate a sentinel role for sCD14 in human milk during bacterial colonization of the gut, and suggest that m-sCD14 may be involved in modulating local innate and adaptive immune responses, thus controlling homeostasis in the neonatal intestine.

Divergent response to LPS and bacteria in CD14-deficient murine macrophages

Gram-negative bacteria and the LPS constituent of their outer membranes stimulate the release of inflammatory mediators believed to be responsible for the clinical manifestations of septic shock. The GPI-linked membrane protein, CD14, initiates the signaling cascade responsible for the induction of this inflammatory response by LPS. In this paper, we report the generation and characterization of CD14-null mice in which the entire coding region of CD14 was deleted. As expected, LPS failed to elicit TNF-alpha and IL-6 production in macrophages taken from these animals, and this loss in responsiveness is associated with impaired activation of both the NF-kappaB and the c-Jun N-terminal mitogen-activated protein kinase pathways. The binding and uptake of heat-killed Escherichia coli, measured by FACS analysis, did not differ between CD14-null and wild-type macrophages. However, in contrast to the findings with LPS, whole E. coli stimulated similar levels of TNF-alpha release from CD14-null and wild-type macrophages at a dose of 10 bioparticles per cell. This effect was dose dependent, and at lower bacterial concentrations CD14-deficient macrophages produced significantly less TNF-alpha than wild type. Approximately half of this CD14-independent response appeared to be mediated by CD11b/CD18, as demonstrated by receptor blockade using neutrophil inhibitory factor. An inhibitor of phagocytosis, cytochalasin B, abrogated the induction of TNF-alpha in CD14-deficient macrophages by E. coli. These data indicate that CD14 is essential for macrophage responses to free LPS, whereas other receptors, including CD11b/CD18, can compensate for the loss of CD14 in response to whole bacteria.

Candidate serological biomarkers for cancer identified from the secretomes of 23 cancer cell lines and the human protein atlas

Although cancer cell secretome profiling is a promising strategy used to identify potential body fluid-accessible cancer biomarkers, questions remain regarding the depth to which the cancer cell secretome can be mined and the efficiency with which researchers can select useful candidates from the growing list of identified proteins. Therefore, we analyzed the secretomes of 23 human cancer cell lines derived from 11 cancer types using one-dimensional SDS-PAGE and nano-LC-MS/MS performed on an LTQ-Orbitrap mass spectrometer to generate a more comprehensive cancer cell secretome. A total of 31,180 proteins was detected, accounting for 4,584 non-redundant proteins, with an average of 1,300 proteins identified per cell line. Using protein secretion-predictive algorithms, 55.8% of the proteins appeared to be released or shed from cells. The identified proteins were selected as potential marker candidates according to three strategies: (i) proteins apparently secreted by one cancer type but not by others (cancer type-specific marker candidates), (ii) proteins released by most cancer cell lines (pan-cancer marker candidates), and (iii) proteins putatively linked to cancer-relevant pathways. We then examined protein expression profiles in the Human Protein Atlas to identify biomarker candidates that were simultaneously detected in the secretomes and highly expressed in cancer tissues. This analysis yielded 6-137 marker candidates selective for each tumor type and 94 potential pan-cancer markers. Among these, we selectively validated monocyte differentiation antigen CD14 (for liver cancer), stromal cell-derived factor 1 (for lung cancer), and cathepsin L1 and interferon-induced 17-kDa protein (for nasopharyngeal carcinoma) as potential serological cancer markers. In summary, the proteins identified from the secretomes of 23 cancer cell lines and the Human Protein Atlas represent a focused reservoir of potential cancer biomarkers.

Serum lipopolysaccharide-binding protein in endotoxemic patients with inflammatory bowel disease

BACKGROUND

In inflammatory bowel disease (IBD), enhanced inflammatory activity in the gut is thought to increase the risk of bacterial translocation and endotoxemia. By searching for signs of endotoxin-signaling cascade activation, including augmented levels of endotoxin, lipopolysaccharide-binding protein (LBP), and soluble CD14 receptor (sCD14), this prospective study sought to establish whether endotoxemia could contribute to greater clinical activity of disease.

METHODS

Concentrations of plasma endotoxin, LBP, sCD14, several cytokines, acute phase proteins and clinical activity indices were determined in 104 patients with Crohn's disease (CD) and 52 patients with ulcerative colitis (UC).

RESULTS

Endotoxemia was present in 48% of the patients with CD and in 28% of the patients with UC. The mean LBP was higher in patients with active CD (23.1 +/- 13.7 microg/mL) and UC (21.4 +/- 10.9 microg/mL) than in healthy controls (7.2 +/- 1.8 microg/mL; P < 0.01). Elevated serum concentrations of endotoxin and LBP were even detected in patients with inactive CD. Among the patients with active IBD, those with higher endotoxin levels had the worst clinical activity scores and the highest LBP levels. Treatment normalized LBP concentrations, from 29.1 +/- 13.0 to 15.2 +/- 7.3 microg/mL; (P < 0.05) in active CD and from 21.7 +/- 9.8 to 13.6 +/- 5.7 microg/mL; (P < 0.01) in active UC, along with normalizing endotoxin and sCD14 plasma concentrations.

CONCLUSIONS

Patients with IBD show increased serum levels of endotoxin, LBP and sCD14. This alteration correlates with disease activity, with normal levels recovered after treatment, although less completely in Crohn's disease, and parallels a rise in proinflammatory cytokines, suggesting a contribution of bacterial products to the inflammatory cascade in these patients.

Myeloid-derived suppressor cell measurements in fresh and cryopreserved blood samples

Myeloid-derived suppressor cells (MDSC) present in the human peripheral blood, represent a heterogeneous population of cells with monocytic and granulocytic features. To provide guidelines for reliable assessments of the frequency and function of MDSC, we compared fresh vs. cryopreserved peripheral blood mononuclear cell (PBMC) samples obtained from normal controls and patients with cancer. PBMC were obtained from 4 healthy donors and 21 patients with cancer. They were stained with labeled antibodies, and the frequency of DR⁻/LIN⁻/CD11b+, DR⁻/LIN⁻/CD15+, DR⁻/LIN⁻/CD33+ and DR(-/low)/CD14+ cells was determined by flow cytometry before and after cryopreservation. CFSE-based suppressor assays were used to test inhibitory functions of MDSC. Arginase I expression and reactive oxygen species (ROS) upregulation in MDSC subsets were evaluated by flow cytometry. The DR(-/low)/CD14+ and DR⁻/LIN⁻/CD11b+ subsets of MDSC were found to be more resistant to the cryopreservation/thawing procedure compared to the DR⁻/LIN⁻/CD15+ and DR⁻/LIN⁻/CD33+ subsets. The frequency of the latter two MDSC subsets was significantly reduced after cryopreservation. All but DR⁻/LIN⁻/CD15+ cells inhibited proliferation of autologous CSFE-labeled CD4+ cells but lost suppressor activity after cryopreservation. Only DR⁻/LIN-/CD15+ cells were positive for Arginase I, but lost its expression after cryopreservation. Only fresh DR⁻/LIN⁻/CD11b+ and DR⁻/LIN⁻/CD15+ cells produced ROS after in vitro stimulation. Studies of human MDSC should be performed in fresh blood samples. If samples have to be cryopreserved, monitoring of CD11b+ and CD14+ MDSC subsets provides the most reliable results. Arginase I expression or stimulated ROS production assessed by flow cytometry are useful markers for MDSC subsets only in fresh samples.

A TLR4 polymorphism is associated with asthma and reduced lipopolysaccharide-induced interleukin-12(p70) responses in Swedish children

BACKGROUND

Bacterial signals play an important role in the maturation of the immune system. Polymorphisms in genes coding for receptors to bacterial components can alter the immune responsiveness of the host to microbial agents and may indicate the development of aberrant immune responses that are associated with immune-mediated diseases such as atopic diseases.

OBJECTIVE

The study's objective was to investigate the relationship between TLR4 and CD14 gene polymorphisms, the LPS responsiveness of PBMCs, and the presence of asthma and allergic rhinoconjunctivitis in children.

METHODS

The TLR4 (Asp299Gly) and CD14/-159 polymorphisms were determined in 115 Swedish children aged 8 and 14 years. LPS-induced IL-12(p70), IL-10, and IFN-gamma responses of PBMCs from 69 of the children were analyzed by means of ELISA. The levels of soluble CD14 in serum samples were analyzed by means of ELISA, and the total IgE levels were analyzed by means of UniCAP Total IgE (Pharmacia Diagnostics, Uppsala, Sweden).

RESULTS

Decreased LPS-induced IL-12(p70) and IL-10 responses were associated with the TLR4 (Asp299Gly) polymorphism and independently with asthma, especially atopic asthma. The TLR4 (Asp299Gly) polymorphism was associated with a 4-fold higher prevalence of asthma in school-aged children (adjusted odds ratio 4.5, 95% CI 1.1-17.4) but not to allergic rhinoconjunctivitis.

CONCLUSION

A TLR4 polymorphism modifies innate immune responses in children and may be an important determinant for the development of asthma. This may influence the outcome of intervention studies that use microbial stimuli as immune modulators.

Invasive assessment of bacterial endotoxin and inflammatory cytokines in patients with acute heart failure

AIMS

To test the hypothesis that during acute heart failure endotoxin might be increased in hepatic veins as a sign of bacterial or endotoxin translocation from the bowel into the blood stream.

METHODS AND RESULTS

In patients with acute heart failure (NYHA IV; n=17) levels of endotoxin, soluble (s) CD14, tumor necrosis factor alpha (TNFalpha and interleukin 6 (IL6)) were measured in blood drawn from an antecubital vein on admission and compared with age-matched patients with stable chronic heart failure (n=21) and healthy volunteers (n=9). All levels were systemically elevated during acute heart failure (all P<0.05); once patients were stable enough to undergo cardiac catheterization, endotoxin was found to be significantly higher in hepatic veins (0.62+/-0.05 EU/ml) than left ventricles (0.46+/-0.04 EU/ml; P<0.05), whereas sCD14, TNFalpha and IL6 were not different between these sites. At follow-up (29+/-6 days) endotoxin but not sCD14, TNFalpha or IL-6 was significantly lower as compared to baseline (P<0.05).

CONCLUSIONS

Higher levels of endotoxin in hepatic veins as compared to the left ventricle during acute heart failure are suggestive of bacterial or endotoxin translocation from the bowel into the blood stream. This may lead to new treatment strategies. The lack of difference in TNFalpha levels between the pulmonary artery and the left ventricle sheds doubt on the heart as a source of systemically elevated TNFalpha levels.