A polymorphism in CD14 modifies the effect of farm milk consumption on allergic diseases and CD14 gene expression

BACKGROUND

Consumption of farm milk in early life is associated with less asthma and allergies.

OBJECTIVE

We hypothesized that genetic variation in the innate immunity receptor CD14 might modify the association between farm milk consumption and asthma and atopy.

METHODS

Questionnaire data, serum IgE levels, and genotypes for 4 single nucleotide polymorphisms in CD14 were assessed in farmers' and nonfarmers' children from 2 European populations (Allergy and Endotoxin study, n = 576; Prevention of Allergy Risk factors for Sensitization in children related to Farming and Anthroposophic Lifestyle study, n = 1539). In a subsample (n = 222) CD14 gene expression was measured in peripheral blood leukocytes. The effects of farm milk and CD14 genotypes on asthma, allergies, and CD14 expression and their interactions were investigated.

RESULTS

We found a significant interaction between genetic variation in CD14/-1721 and farm milk consumption. Adjusted odds ratios for the association between farm milk and asthma varied between the genotypes: AA, 0.18 (95% CI, 0.07-0.47); AG, 0.47 (95% CI, 0.26-0.86); and GG, 0.98 (95% CI, 0.46-2.08). Similar patterns were observed for symptoms of allergic rhinoconjunctivitis and pollen sensitization. CD14/-1721 also modified the association between farm milk and CD14 gene expression (adjusted geometric means ratios: AA, 1.61 (95% CI, 0.98-2.66); AG, 1.11 (95% CI, 0.71-1.72); and GG, 0.76 (95% CI, 0.39-1.48).

CONCLUSION

The protective effect of farm milk consumption on allergic diseases is stronger in children carrying the A allele in CD14/-1721 than in children homozygous for the G allele. This might be mediated through farm milk-induced upregulated CD14 gene expression.

CLINICAL IMPLICATIONS

Our results support the hypothesis that the inverse association between farm milk consumption and allergic diseases is mediated by CD14-activated innate immune mechanisms.

Increases in circulating T lymphocytes expressing HLA-DR and CD40 ligand in patients with dilated cardiomyopathy

Inflammatory and immunological mechanisms are implicated in the development of idiopathic dilated cardiomyopathy (DCM). Since activated T lymphocytes express surface HLA-DR antigens, an increased level of these cells in the circulation could indicated an ongoing immune response. While the role of activated T lymphocytes in experimental myocarditis has been elucidated, the contribution of T lymphocyte activation in clinical DCM remains unclear. We therefore examined the role of T-cell activation in peripheral blood samples obtained from 10 patients with DCM (mean age, 49 +/- 12 years) and from 10 age-matched healthy controls. Citrated whole blood was mixed with fluorescein isothiocyanate- or phycoerythrin-conjugated specific monoclonal antibodies and analyzed using a fluorescence-activated cell sorter (FACS). The ratio (%) of histocompatibility leukocyte antigen (HLA)-DR positive cells in the FACS gated lymphocyte population was significantly higher in DCM patients than in controls (7.9% +/- 5.3% vs 2.0% +/- 0.9%; P < 0.01). The expression of CD40L on T cells determined as mean fluorescence intensity (MFI) was also significantly higher in DCM patients than in controls (3.6 +/- 2.1 vs 1.8 +/- 0.4 MFI; P < 0.05). Furthermore, the ratios of T cells expressing HLA-DR and serum brain natriuretic peptide (BNP) levels closely correlated (P = 0.0008). We showed that HLA-DR on peripheral T cells significantly correlated with serum BNP levels and that high CD40L expression on T cells was concomitant with increased BNP levels (P < 0.05). Therefore the magnitude of T-cell expression, such as increased expression of HLA-DR and CD40L, contributes to myocardial dysfunction in DCM.

TNF-alpha drives human CD14+ monocytes to differentiate into CD70+ dendritic cells evoking Th1 and Th17 responses

Many mechanisms involving TNF-alpha, Th1 responses, and Th17 responses are implicated in chronic inflammatory autoimmune disease. Recently, the clinical impact of anti-TNF therapy on disease progression has resulted in re-evaluation of the central role of this cytokine and engendered novel concept of TNF-dependent immunity. However, the overall relationship of TNF-alpha to pathogenesis is unclear. Here, we demonstrate a TNF-dependent differentiation pathway of dendritic cells (DC) evoking Th1 and Th17 responses. CD14(+) monocytes cultured in the presence of TNF-alpha and GM-CSF converted to CD14(+) CD1a(low) adherent cells with little capacity to stimulate T cells. On stimulation by LPS, however, they produced high levels of TNF-alpha, matrix metalloproteinase (MMP)-9, and IL-23 and differentiated either into mature DC or activated macrophages (M phi). The mature DC (CD83(+) CD70(+) HLA-DR (high) CD14(low)) expressed high levels of mRNA for IL-6, IL-15, and IL-23, induced naive CD4 T cells to produce IFN-gamma and TNF-alpha, and stimulated resting CD4 T cells to secret IL-17. Intriguingly, TNF-alpha added to the monocyte culture medium determined the magnitude of LPS-induced maturation and the functions of the derived DC. In contrast, the M phi (CD14(high)CD70(+)CD83(-)HLA-DR(-)) produced large amounts of MMP-9 and TNF-alpha without exogenous TNF stimulation. These results suggest that the TNF priming of monocytes controls Th1 and Th17 responses induced by mature DC, but not inflammation induced by activated M phi. Therefore, additional stimulation of monocytes with TNF-alpha may facilitate TNF-dependent adaptive immunity together with GM-CSF-stimulated M phi-mediated innate immunity.

Calcitriol and calcium regulate cytokine production and adipocyte-macrophage cross-talk

OBJECTIVE

The objective of this study was to investigate the effects of calcitriol on adipocyte and macrophage cytokine expression as well as release and on adipocyte-macrophage cross-talk in local modulation of inflammation.

RESEARCH PROCEDURES AND RESULTS

We investigated calcitriol modulation of the expression of macrophage inhibitory factor (MIF) and macrophage surface-specific protein CD14, two key factors in regulating macrophage function and survival, in differentiated human adipocytes. Calcitriol significantly increased MIF and CD14 expression by 59% and 33%, respectively, while calcium-channel antagonism with nifedipine completely reversed these effects, indicating that calcitriol stimulates MIF and CD14 expression via a calcium-dependent mechanism. Similar results were also found in cultured 3T3-L1 adipocytes; in addition, calcitriol also up-regulated macrophage colony-stimulating factor, macrophage inflammatory protein, interleukin-6 (IL-6) as well as monocyte chemoattractant protein-1 expression in 3T3-L1 adipocytes and stimulated tumor necrosis factor as well as IL-6 expression in RAW 264 macrophages. These effects were blocked by either a calcium-channel antagonist (nifedipine) or a mitochondrial uncoupler (dinitrophenol). Moreover, co-culture of 3T3-L1 adipocytes with RAW 264 macrophages significantly increased the expression and production of multiple inflammatory cytokines in response to calcitriol in both cell types.

CONCLUSIONS

These data demonstrate that calcitriol regulates local inflammation via modulating the interaction between adipocytes and macrophages as well as regulating inflammatory cytokine production in each cell type via calcium-dependent and mitochondrial uncoupling-dependent mechanisms. These data provide further mechanistic explanation for our recent observations that suppression of calcitriol by dietary calcium reduces inflammatory cytokine expression and oxidative stress in adipose tissue.

[Characterization and biological significance of peripheral blood dendritic cell subsets in patients with severe burn]

OBJECTIVE

To investigate the characteristics of dendritic cells (DCs) in patients with severe burn.

METHODS

Peripheral blood samples were obtained from 12 patients with severe burn 1, 2, 3, and 4 weeks after burn, and from 10 healthy donors as controls. Mononuclear cells were isolated, and GM-CSF 1000 and IL-4 were used to induce the transformation of DCs. Mature DCs were harvested and underwent flow cytometry to detect the expression of HLA-DR, CD80, CD83, CD86, CD14, and CD11c.

RESULT

1, 2, 3, and 4 weeks after burn, the expression levels of HLA-DR were 62.1% +/- 8.4%, 65.0% +/- 6.2%, 68.4% +/- 5.7%, and 75.4% +/- 8.4% respectively; the expression levels of CD80 were 12.9% +/- 3.7%, 14.7% +/- 2.5%, 16.1% +/- 4.2%, and 16.2% +/- 4.8%; the expression levels of CD83 were 15.1% +/- 4.2%, 15.1% +/- 4.0%, 22.2% +/- 7.7%, and 21.3% +/- 7.0% respectively; the expression levels of CD86 were 69.2% +/- 7.1%, 70.5% +/- 5.4%, 75.1% +/- 6.1%, and 79.6% +/- 6.4% respectively, all significantly lower than that of the control group (84.3% +/- 8.2%, all P < 0.001). 1, 2, 3, and 4 weeks after burn, the expression levels of CD14 in the DCs of the severe burn patients were 12.7% +/- 1.9%, 12.0% +/- 1.5%, 11.3% +/- 1.3%, and 9.3% +/- 1.7% respectively, all significantly higher than that of the control group (7.3% +/- 1.5%, P < 0.001). 1, 2, 3, and 4 weeks after burn, the expression levels of CD11c in the DCs of the severe burn patients were 86.8% +/- 6.1%, 89.5% +/- 5.1%, 91.3% +/- 2.8%, and 89.4% +/- 4.0% respectively, a little lower than that of the control group, however, without significant difference (92.6% +/- 3.8%, P > 0.05).

CONCLUSION

The functions of DCs in the patients with severe burn are declined, which may partly contribute to infection after burn.

Platelet-Derived Growth Factor Receptor Regulates Myeloid and Monocytic Differentiation of HL-60 Cells

Here, we show that the platelet-derived growth factor receptor (PDGFR) regulates myeloid and monocytic differentiation of HL-60 myeloblastic leukemia cells in response to retinoic acid (RA) and vitamin D3 (D3), respectively. Both RA and D3 decreased the expression of PDGFR-alpha and PDGFR-beta throughout differentiation. When cells were treated with the PDGFR inhibitor AG1296 in addition to RA or D3, signs of terminal differentiation such as inducible oxidative metabolism and cell substrate adhesion were enhanced. These changes were accompanied by an increased extracellular signal-regulated kinase 1/2 activation. AG1296 also resulted in elevated expression of differentiation markers CD11b and CD66c when administered with RA or D3. Interestingly, other markers did not follow the same pattern. Cells receiving AG1296 in addition to RA or D3 showed decreased G1-G0 arrest and CD14, CD38, and CD89 expression. We thus provide evidence that certain sets of differentiation markers can be enhanced, whereas others can be inhibited by the PDGFR pathway. In addition, we found calcium levels to be decreased by RA and D3 but increased when AG1296 was given in addition to RA or D3, suggesting that calcium levels decrease during myeloid or monocytic differentiation, and elevated calcium levels can disturb the expression of certain differentiation markers.

Myeloproliferative Defects following Targeting of the Drf1 Gene Encoding the Mammalian Diaphanous–Related Formin mDia1

Rho GTPase-effector mammalian diaphanous (mDia)-related formins assemble nonbranched actin filaments as part of cellular processes, including cell division, filopodia assembly, and intracellular trafficking. Whereas recent efforts have led to thorough characterization of formins in cytoskeletal remodeling and actin assembly in vitro, little is known about the role of mDia proteins in vivo. To fill this knowledge gap, the Drf1 gene, which encodes the canonical formin mDia1, was targeted by homologous recombination. Upon birth, Drf1+/- and Drf1-/- mice were developmentally and morphologically indistinguishable from their wild-type littermates. However, both Drf1+/- and Drf1-/- developed age-dependent myeloproliferative defects. The phenotype included splenomegaly, fibrotic and hypercellular bone marrow, extramedullary hematopoiesis in both spleen and liver, and the presence of immature myeloid progenitor cells with high nucleus-to-cytoplasm ratios. Analysis of cell surface markers showed an age-dependent increase in the percentage of CD11b+-activated and CD14+-activated monocytes/macrophages in both spleen and bone marrow in Drf1+/- and Drf1-/- animals. Analysis of the erythroid compartment showed a significant increase in the proportion of splenic cells in S phase and an expansion of erythroid precursors (TER-119+ and CD71+) in Drf1-targeted mice. Overall, knocking out mDia1 expression in mice leads to a phenotype similar to human myeloproliferative syndrome (MPS) and myelodysplastic syndromes (MDS). These observations suggest that defective DRF1 expression or mDia1 function may contribute to myeloid malignancies and point to mDia1 as an attractive therapeutic target in MDS and MPS.

EFFECTS OF CD14-159 C/T POLYMORPHISM ON CD14 EXPRESSION AND THE BALANCE BETWEEN PROINFLAMMATORY AND ANTI-INFLAMMATORY CYTOKINES IN WHOLE BLOOD CULTURE

CD14 is an important receptor of innate immunity. When CD14 is anchored by ligands to LPS, peptidoglycans, or lipoteichoic acid, it can result in either proinflammatory or anti-inflammatory responses. To determine whether CD14-159 C/T polymorphism is associated with CD14 expression and the balance of proinflammatory and anti-inflammatory responses, we studied 118 healthy ethnic Han Chinese using a whole blood culture model. The CD14-159 C/T polymorphism was determined by polymerase chain reaction and subsequent HaeIII restriction enzyme digestion of the polymerase chain reaction products. Meanwhile, CD14 mRNA expression in leukocytes and the levels of soluble CD14, TNF-alpha, IL-6, and IL-10 were also determined in the supernatants. Among the 118 individuals, there were 40 TT homozygotes, 62 heterozygotes, and 16 subjects homozygous for C allele. After LPS stimulation, the levels of CD14 mRNA expression in TT and TC genotypes were significantly higher than in CC homozygotes (P = 0.017), and soluble CD14 levels were also higher than in CC genotypes (P = 0.008). In addition, TT homozygotes had the highest LPS-stimulated TNF-alpha, IL-6 production (P = 0.044, P = 0.004), and the lowest IL-10 release (P = 0.003). In conclusion, CD14-159 C/T polymorphism is correlated with CD14 expression and may thus influence the balance of proinflammatory and anti-inflammatory responses in ethnic Han Chinese. These results suggest that CD14-159 C/T polymorphism might partly explain the difference in predisposition to develop complications of infectious diseases in different patients and may provide a therapeutic target for sepsis intervention strategies.

Soluble CD14 and CD83 from human neonatal antigen-presenting cells are inducible by commensal bacteria and suppress allergen-induced human neonatal Th2 differentiation

CD14 is expressed on the cell surface of various antigen-presenting cells, and CD83 is a maturation marker for dendritic cells (DC). CD14 and CD83 are also present as soluble proteins, and both have immunoregulatory functions. We examined whether neonatal cord blood monocytes or DC released soluble CD14 (sCD14) or sCD83 when exposed to the commensal intestinal bacteria Clostridium perfringens, Staphylococcus aureus, Lactobacillus rhamnosus, Escherichia coli, and Bacteroides fragilis. We found that the gram-positive bacteria C. perfringens and S. aureus, but not gram-negative bacteria, induced the release of sCD14 from monocytes. DC, on the other hand, released sCD14 in response to both gram-positive and gram-negative bacteria. Moreover, the expression of the virulence factor staphylococcal protein A seemed to be important for S. aureus-induced sCD14 production from both monocytes and DC. Soluble CD83 was released from DC, but not from monocytes, when exposed to both gram-positive and gram-negative bacteria. Finally, to investigate whether sCD14 or sCD83 could modulate neonatal allergen-induced T-cell differentiation, DC were exposed to birch allergen alone or in the presence of sCD14 or sCD83 and then cocultured with autologous T cells. We demonstrate that sCD14 and sCD83 inhibited the birch allergen-induced Th2 differentiation by suppressing interleukin 13 production. Together, these results suggest that the commensal intestinal flora may be an important stimulus for the developing immune system by inducing the immunoregulatory proteins sCD14 and sCD83, which may be involved in preventing T-cell sensitization to allergens in infants.

CD14-159 C allele is associated with increased risk of mortality after burn injury

Although comprehension of postburn pathophysiology has grown in recent years, we are still unable to accurately identify burn patients who are at an increased risk of infectious complications and death. This unexplained variation is likely influenced by heritable factors; the genetic predisposition for death from infection has been estimated as greater than that for cardiovascular disease or cancer. Identify genetic variants associated with increased mortality after burn injury. A total of 233 patients with burns of 15% of total body surface area or greater or smoke inhalation injury who survived more than 48 h after admission and were without significant nonburn-related trauma (injury severity score > or = 16), traumatic or anoxic brain injury, or spinal cord injury. We examined the influence of genotype at five candidate loci (interleukin [IL]-1beta, IL-6, tumor necrosis factor-alpha, toll-like receptor 4, CD14) on mortality risk after burn injury. DNA was isolated from residual blood from laboratory draws and candidate genotypes were determined by real-time polymerase chain reaction using TaqMan probes. Clinical data were prospectively collected into a local, curated database. Allelic associations were analyzed by multivariate logistic regression. After adjustment for age, full-thickness burn size, inhalation injury, ethnicity, and sex, carriage of the CD14-159 C allele imparted at least a 1.3-fold increased risk for death after burn injury, relative to TT homozygotes (adjusted odds ratio, 2.9; 95% confidence interval, 1.3-6.8; P = 0.01). This association was stronger (adjusted odds ratio, 3.3; 95% confidence interval, 1.3-8.4; P = 0.01) when the analysis was conducted only on deaths accompanied by severe sepsis. In addition, a gene dosage effect for increased mortality was apparent for carriage of the CD14-159 C allele (P = 0.006). The gene dosage effect remained when white, Hispanic, or African American patients were analyzed independently, although statistical significance was not achieved in the subgroup analysis. None of the other single nucleotide polymorphisms examined were significantly associated with mortality. These data provide strong evidence that a CD14 promoter allele that is known to impart lower baseline and induced CD14 transcription also affects mortality risk after burn injury. A potential (although untested) mechanism for our observation is that reduced signaling through CD14/toll-like receptor 4 in response to challenge by gram-negative bacteria after burns results in a blunted innate immune response and subsequent increased likelihood for systemic infection and death.

Streptococcus suisSerotype 2, an Important Swine and Human Pathogen, Induces Strong Systemic and Cerebral Inflammatory Responses in a Mouse Model of Infection

Streptococcus suis, an important swine and human pathogen, causes septic shock and meningitis. The pathogenesis of both systemic and CNS infections caused by S. suis is poorly understood. A hematogenous model of infection in CD1 mice was developed to study the systemic release of cytokines during the septic shock phase and the proinflammatory events in the CNS associated with this pathogen. Using a liquid array system, high levels of systemic TNF-alpha, IL-6, IL-12, IFN-gamma, CCL2, CXCL1, and CCL5 were observed 24 h after infection and might be responsible for the sudden death of 20% of animals. Infected mice that survived the early sepsis later developed clinical signs of meningitis and exhibited lesions in the meninges and in numerous regions of the brain, such as the cortex, hippocampus, thalamus, hypothalamus, and corpus callosum. Bacterial Ags were found in association with microglia residing only in the affected zones. In situ hybridization combined with immunocytochemistry showed transcriptional activation of TLR2 and TLR3 as well as CD14, NF-kappaB, IL-1beta, CCL2, and TNF-alpha, mainly in myeloid cells located in affected cerebral structures. Early transcriptional activation of TLR2, CD14, and inflammatory cytokines in the choroid plexus and cells lining the brain endothelium suggests that these structures are potential entry sites for the bacteria into the CNS. Our data indicate an important role of the inflammatory response in the pathogenesis of S. suis infection in mice. This experimental model may be useful for studying the mechanisms underlying sepsis and meningitis during bacterial infection.

Binding of caspase-3 prodomain to heat shock protein 27 regulates monocyte apoptosis by inhibiting caspase-3 proteolytic activation

Caspase-3 is an essential executioner of apoptosis responsible for regulating many important cellular processes, among them the number of circulating monocytes, central players in the innate immune response. The activation of caspase-3 requires its processing from an inactive precursor. Here we show that the small heat shock protein 27 (Hsp27) associates with caspase-3 and protein-protein interaction experiments in vivo and with purified proteins demonstrate a direct interaction between Hsp27 and the amino-terminal prodomain of caspase-3. Using an in vitro caspase-3 activation assay, our results further establish that the interaction of Hsp27 with the caspase-3 prodomain inhibits the second proteolytic cleavage necessary for caspase-3 activation, revealing a novel mechanism for the regulation of this effector caspase. Hsp27 expression in monocytes is constitutive. Consistent with a central role of Hsp27 in blocking caspase-3 activation, Hsp27 down-regulation by double-stranded RNA interference induces apoptosis of macrophages, whereas Hsp27 overexpression increases the life span of monocytes by inhibiting apoptosis. Highlighting the importance of cell partitioning in the regulation of apoptosis, immunofluorescence, and subcellular fractionation studies revealed that whereas both caspase-3 and Hsp27 are cytoplasmic in fresh monocytes (i.e. not undergoing apoptosis), Hsp27 moves to the nucleus during apoptosis, a relocalization that can be blocked by promoting the differentiation of monocytes to macrophages or by inhibiting cell death. These results reveal a novel mechanism of caspase-3 regulation and underscore a novel and fundamental role of Hsp27 in the regulation of monocyte life span.

Efficient activation of autologous tumor-specific T cells: a simple coculture technique of autologous dendritic cells compared to established cell fusion strategies in primary human colorectal carcinoma

Different technologies have been employed to deliver the whole spectrum of tumor antigens (TAs) to dendritic cells (DCs) to be presented to T cells. These include whole tumor RNA-transfected DCs, preparations of DCs loaded with tumor-derived apoptotic bodies or tumor cell lysates, and DC tumor cell fusions. Early clinical trials have been conducted using such techniques. The presented study was aimed to revisit the necessity of tumor cell manipulation in DC-based immunotherapy strategies for colorectal carcinoma. We investigated a simple coculture method of autologous monocyte-derived DCs and human primary colorectal carcinoma (pCC) in comparison with 2 well-described cell fusion strategies for the efficacy of uptake, processing and presentation of TAs to autologous T cells. Before coculture or fusion, pCC had been cryopreserved without further manipulation. Fluorescence microscopy and flow cytometry analyses of fluorescent dye labeled cells were used for monitoring engulfment of pCC by DCs. The coculture procedure resulted in a double positive cell fraction of up to 22% and thus was comparable to that observed after cell fusion. More important, DCs after coculture with autologous pCC induced significant tumor-specific interferon-gamma-producing autologous T cells in the same number of patients as DC/pCC fusions. Furthermore, tumor-specific major histocompatibility complex class I restricted cytotoxic T lymphocytes were generated by stimulation with DCs cocultured with pCC. In prior studies for human carcinomas coculture techniques were described to be inferior. In contrast, our data strongly suggest that at least for human pCC and autologous DCs this simple coculture method is similarly efficient compared to established fusion techniques.

An anti-endotoxin peptide that generates from the amino-terminal domain of complement regulatory protein C1 inhibitor

C1 inhibitor (C1INH), a complement regulatory protein, prevents endotoxin shock via a direct interaction of the amino-terminal domain with gram-negative bacterial lipopolysaccharide (LPS). Importantly, the cleaved, inactive C1INH still is an anti-endotoxin effector indicating the anti-endotoxin peptide that generates from the amino-terminal domain of C1INH. In this study, we first identified that a cleaved fragment within the major part of the amino-terminal domain in in vitro proteolytic analysis of C1INH had an ability to bind to LPS. We synthesized several peptides overlapping the C1INH cleaved fragment. Among these synthetic peptides, a 13-mer derivative peptide at position from 18 to 30, named N2((18-30)), exhibited the most powerful anti-endotoxin activity in vitro, enlightening that it was most strong at binding to LPS, inhibiting the interaction of LPS with LPS-binding protein (LBP), blocking LPS binding to CD14(+) cells, and suppressing production of tumor necrosis factor (TNF)-alpha by murine macrophages, RAW 264.7. In the murine endotoxin shock model, the peptide N2((18-30)) protected mice from LPS-induced lethal septic shock by inhibiting macrophage activation. These data indicate that the peptide N2((18-30)) derived from the amino-terminal region of C1INH is anti-endotoxin.

Optimized THP-1 differentiation is required for the detection of responses to weak stimuli

OBJECTIVES

The differentiation of THP-1 monocytes into macrophages is mainly conducted at a phorbol 12-myristate 13-acetate (PMA) concentration of 10-400 ng/ml. However, this concentration might be high enough to upregulate the expressions of some genes in differentiated macrophages, which could overwhelm gene expression increases induced by other stimuli. The present study was performed to optimize the PMA concentration required to differentiate monocytes whilst minimizing gene upregulation.

METHODS

THP-1 cells were treated with 2.5-100 ng/ml PMA and analyzed for the extent of cell adherence, the surface marker of macrophages, and stable differentiation without undesirable gene upregulation. The stably differentiated THP-1 cells at the minimum PMA concentration were treated with 10 ng/ml LPS or 125 nM amyloid beta (Abeta(1-42)).

RESULTS

The treatment of THP-1 with 5 ng/ml PMA was found to be sufficient to induce stable differentiation without undesirable gene upregulation. These macrophages differentiated at 5 ng/ml responded well to secondary weak stimuli like 10 ng/ml LPS or 125 nM of amyloid beta (Abeta(1-42)).

CONCLUSIONS

This finding suggests that THP-1 cells are well differentiated by 5 ng/ml PMA, and that the resulting differentiated macrophages respond well to secondary weak stimuli without being overwhelmed by undesirable gene upregulation induced by PMA.

The CD16+Monocyte Subset Is More Permissive to Infection and Preferentially Harbors HIV-1 In Vivo

HIV-1 persists in peripheral blood monocytes in individuals receiving highly active antiretroviral therapy (HAART) with viral suppression, despite these cells being poorly susceptible to infection in vitro. Because very few monocytes harbor HIV-1 in vivo, we considered whether a subset of monocytes might be more permissive to infection. We show that a minor CD16+ monocyte subset preferentially harbors HIV-1 in infected individuals on HAART when compared with the majority of monocytes (CD14highCD16-). We confirmed this by in vitro experiments showing that CD16+ monocytes were more susceptible to CCR5-using strains of HIV-1, a finding that is associated with higher CCR5 expression on these cells. CD16+ monocytes were also more permissive to infection with a vesicular stomatitis virus G protein-pseudotyped reporter strain of HIV-1 than the majority of monocytes, suggesting that they are better able to support HIV-1 replication after entry. Consistent with this observation, high molecular mass complexes of apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G (APOBEC3G) were observed in CD16+ monocytes that were similar to those observed in highly permissive T cells. In contrast, CD14highCD16- monocytes contained low molecular mass active APOBEC3G, suggesting this is a mechanism of resistance to HIV-1 infection in these cells. Collectively, these data show that CD16+ monocytes are preferentially susceptible to HIV-1 entry, more permissive for replication, and constitute a continuing source of viral persistence during HAART.

Targeting bacterial endotoxin: two sides of a coin

The term sepsis describes a potentially lethal clinical condition that develops as a result of a dysregulated host response to bacterial infection. The most common bacterial component implicated in initiating the septic syndrome is a cell wall molecule derived from Gram-negative bacteria, known as lipopolysaccharide (LPS) or endotoxin. Like all mammals, humans are equipped with an LPS-sensing machinery consisting, primarily, of LPS-binding protein (LBP), CD14, a glycosylphosphatidylinositol (GPI)-anchored monocyte differentiation antigen, and toll-like receptor 4 (TLR4), a signal-transducing integral membrane protein. Modest stimulation of TLR4 facilitates the elimination of invading microorganisms. Potent TLR4 stimulation, however, produces severe reactions in the host, often leading to multiple organ failure and death. The search for pharmaceuticals that reduce mortality in septic patients has been a painstaking process. Thus far, only a few compounds have been found to significantly reduce mortality rates. Perhaps one of the more promising therapeutic strategies currently pursued is based on the identification of synthetic or naturally occurring substances that neutralize LPS or inhibit LPS-mediated activation of host immune cells, such as monocytes and macrophages. Here, we describe a number of diverse molecular structures with a capacity to either enhance or blunt LPS-induced monocyte activation. The underlying molecular mechanisms are discussed.

Arginase, prostaglandins, and myeloid-derived suppressor cells in renal cell carcinoma

Tumor-induced tolerance is a well-established phenomenon in cancer patients that can severely impair the therapeutic efficacy of immunotherapy. One mechanism leading to T-cell tolerance is the generation of myeloid-derived suppressor cells (MDSC) by soluble factors produced by the tumor. MDSC express CD11b(+) as a common marker but may vary in their stage of maturation, depending on the tumor factors being produced. Arginase production by MDSC depletes arginine from the tumor microenvironment and impairs T-cell signal transduction and function. We studied whether an increase in MDSC could explain the molecular alterations and dysfunction found in T cells of patients with renal cell carcinoma (RCC). Arginase activity in the peripheral blood mononuclear cells of 117 RCC patients was increased between 6- to 8-fold compared with normal controls. The increased arginase activity was limited to the CD11b(+)CD14(-) myeloid cells and resulted in significantly decreased serum levels of arginine and increased ornithine in patients. Depletion of MDSC restored IFN-gamma production and T-cell proliferation. Preliminary data suggest that prostaglandin E(2) produced by the tumor induces arginase I expression in MDSC. Therefore, blocking MDSC activity may enhance the therapeutic efficacy of immunotherapy in RCC.

Role of TLR4 tyrosine phosphorylation in signal transduction and endotoxin tolerance

In this study, we examined whether tyrosine phosphorylation of the Toll-IL-1 resistance (TIR) domain of Toll-like receptor (TLR) 4 is required for signaling and blocked in endotoxin tolerance. Introduction of the P712H mutation, responsible for lipopolysaccharide (LPS) unresponsiveness of C3H/HeJ mice, into the TIR domain of constitutively active mouse DeltaTLR4 and mutation of the homologous P714 in human CD4-TLR4 rendered them signaling-incompetent and blocked TLR4 tyrosine phosphorylation. Mutations of tyrosine residues Y674A and Y680A within the TIR domains of CD4-TLR4 impaired its ability to elicit phosphorylation of p38 and JNK mitogen-activated protein kinases, IkappaB-alpha degradation, and activation of NF-kappaB and RANTES reporters. Likewise, full-length human TLR4 expressing Y674A or Y680A mutations showed suppressed capacities to mediate LPS-inducible cell activation. Signaling deficiencies of the Y674A and Y680A TLR4s correlated with altered MyD88-TLR4 interactions, increased associations with a short IRAK-1 isoform, and decreased amounts of activated IRAK-1 in complex with TLR4. Pretreatment of human embryonic kidney (HEK) 293/TLR4/MD-2 cells with protein tyrosine kinase or Src kinase inhibitors suppressed LPS-driven TLR4 tyrosine phosphorylation, p38 and NF-kappaB activation. TLR2 and TLR4 agonists induced TLR tyrosine phosphorylation in HEK293 cells overexpressing CD14, MD-2, and TLR4 or TLR2. Induction of endotoxin tolerance in HEK293/TLR4/MD-2 transfectants and in human monocytes markedly suppressed LPS-mediated TLR4 tyrosine phosphorylation and recruitment of Lyn kinase to TLR4, but did not affect TLR4-MD-2 interactions. Thus, our data demonstrate that TLR4 tyrosine phosphorylation is important for signaling and is impaired in endotoxin-tolerant cells, and suggest involvement of Lyn kinase in these processes.

Endotoxin-binding Proteins Modulate the Susceptibility of Bacterial Endotoxin to Deacylation by Acyloxyacyl Hydrolase

Acyloxyacyl hydrolase (AOAH) is an eukaryotic lipase that partially deacylates and detoxifies Gram-negative bacterial lipopolysaccharides and lipooligosaccharides (LPSs or LOSs, endotoxin) within intact cells and inflammatory fluids. In cell lysates or as purified enzyme, in contrast, detergent is required for AOAH to act on LPS or LOS (Erwin, A. L., and Munford, R. S. (1990) J. Biol. Chem. 265, 16444-16449 and Katz, S. S., Weinrauch, Y., Munford, R. S., Elsbach, P., and Weiss, J. (1999) J. Biol. Chem. 274, 36579-36584). We speculated that the sequential interactions of endotoxin (E) with endotoxin-binding proteins (lipopolysaccharide-binding protein (LBP), CD14, and MD-2) might produce changes in endotoxin presentation that would allow AOAH greater access to its substrate, lipid A. To test this hypothesis, we measured the activity of purified AOAH against isolated, metabolically labeled meningococcal LOS and Escherichia coli LPS that were presented either as aggregates (LOSagg or LPSagg)+/-LBP or as monomeric protein (sCD14 or MD-2)-endotoxin complexes. Up to 100-fold differences in the efficiency of endotoxin deacylation by AOAH were observed, with the following rank order of susceptibility to AOAH: E:sCD14>or=endotoxin aggregates (Eagg):LBP (molar ratio of E/LBP 100:1)>>Eagg, Eagg:LBP (E/LBP approximately 1, mol/mol), or E:MD-2. AOAH treatment of LOS-sCD14 produced partially deacylated LOS still complexed with sCD14. The underacylated LOS complexed to sCD14 transferred to MD-2 and thus formed a complex capable of preventing TLR4 activation. These findings strongly suggest that LBP- and CD14-dependent extraction and transfer of endotoxin monomers are accompanied by increased exposure of fatty acyl chains within lipid A and that the acyl chains are then sequestered when LOS binds MD-2. The susceptibility of the monomeric endotoxin-CD14 complex to AOAH may help constrain endotoxin-induced TLR4 activation when endotoxin and membrane CD14 are present in excess of MD-2/TLR-4.

IL-3 can not replace GM-CSF in inducing human monocytes to differentiate into Langerhans cells

Receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) share a common beta subunit. We recently reported that GM-CSF acts in concert with transforming growth factor-beta1 (TGF-beta1) and Notch ligand Delta-1 (Delta-1) to promote the differentiation of human blood monocytes into Langerhans cells. In the present study, we examined whether IL-3, in place of GM-CSF, can induce the development of Langerhans cells from blood monocytes in the presence of TGF-beta1 and Delta-1, because the IL-3 receptor alpha chain was substantially expressed on monocytes. However, the generation of Langerhans cells was not obtained by the combination of IL-3, TGF-beta1 and Delta-1, even though GM-CSF and IL-3 exhibited a similar effect with respect to the differentiation of monocytes into macrophages and dendritic cells. The addition of GM-CSF to the culture supplemented with IL-3, TGF-beta1 and Delta-1 restored the differentiation of monocytes toward Langerhans cells. A microarray analysis revealed that a number of genes including Langerhans cell markers, E-cadherin and Langerin, were specifically expressed in cells from GM-CSF-containing cultures but not in those from IL-3-containing cultures. These data suggest that IL-3 can not replace GM-CSF to induce the differentiation of human monocytes into Langerhans cells in culture.

1alpha,25-dihydroxycholecalciferol activates binding of CREB to a CRE site in the CD14 promoter and drives promoter activity in a phosphatidylinositol-3 kinase-dependent manner

1,25-dihydroxycholecalciferol, also known as 1alpha,25-dihydroxyvitamin D3 or calcitriol, regulates the differentiation and functional properties of mononuclear phagocytes. Many of these effects involve nongenomic signaling pathways, which are not fully understood. Activation of CD14 expression, a monocyte differentiation marker and coreceptor with TLR-2 for bacterial LPS, by calcitriol was shown previously to be PI-3K-dependent [1]; however, the mechanism of gene activation remained undefined. Using a transcription factor-binding array screen coupled with EMSA, we found evidence for PI-3K-dependent activation of CREB in THP-1 cells incubated with calcitriol. Furthermore, analysis of the proximal promoter of human CD14 identified regions that contained up to seven sequences, which showed significant similarity to a canonical CRE sequence, 5'-TGACGTCA-3'. Treatment of THP-1 cells with calcitriol activated CREB binding to one of these regions at Positions -37 to -55, relative to the transcription start site in a PI-3K-dependent manner. This 19-mer region also became transcriptionally active in a reporter assay in response to calcitriol, again dependent on PI-3K. Mutation of the CRE within the 19-mer abolished this activity. Taken together, these results show that calcitriol signaling, leading to activation of the CD14 promoter, involves CREB activation downstream of PI-3K.

Biological activities of 2alpha-substituted analogues of 1alpha,25-dihydroxyvitamin D3 in transcriptional regulation and human promyelocytic leukemia (HL-60) cell proliferation and differentiation

Biological activities of 2alpha-substituted 1alpha,25-dihydroxyvitamin D3 analogues were evaluated in vitro. Their binding affinity was examined with calf thymus cytosolic vitamin D receptor (VDR) and rat plasma vitamin D-binding protein (DBP). In addition, the transcriptional activity of the analogues was measured using a rat 25-hydroxyvitamin D3-24-hydroxylase gene promoter, a human osteocalcin gene promoter, and VDR-GAL4 system. This study investigated the biological activities of 2alpha-substituted analogues in comparison with 2beta-substitued analogues at the molecular level, with regard to the structural differences of alkyl, hydroxyalkyl, hydroxyalkoxy substituents at the 2-position of 1alpha,25-dihydroxyvitamin D3.

Decitabine and vitamin D3 differentially affect hematopoietic transcription factors to induce monocytic differentiation

Standard chemotherapy is not curative for many patients with acute myeloid leukemia (AML). New treatment strategies combining demethylating agents, such as decitabine, and drugs that induce myelomonocytic differentiation (i.e. Vitamin D3) may re-establish functional hematopoiesis in these patients. We studied the effects of decitabine alone or in combination with Vitamin D3 (VD3) on U937 cells and AML blasts. Preincubation with decitabine (0.1-1 microM) and subsequent exposure to VD3 (3 nM) synergistically induced monocytic differentiation. To elucidate the mechanisms of decitabine- and VD3-induced monocytic differentiation, we investigated the effects of the two drugs on transcription factors implicated in monocytic differentiation. Northern and Western blotting showed that decitabine induced transcription of c-jun but not PU.1, while VD3 increased PU.1, IRF8, and C/EBPbeta but not c-jun. Using electromobility shift assays, we demonstrated increased DNA binding of nuclear proteins from decitabine- and VD3-induced U937 cells to the CD11b promoter. In addition, we investigated whether the myeloid transcription factor Sp1 played a role in decitabine- and VD3-induced CD14 expression. Indeed, we found that mithramycin A, a specific inhibitor of Sp1, inhibited both VD3- and decitabine-induced upregulation of CD14, which is in line with previous data showing that Sp1 is critical for CD14 promoter activity. Induction of CD11b and/or CD14 by decitabine and/or VD3 was confirmed in primary AML patient samples at the time of diagnosis. In conclusion, decitabine synergizes with Vitamin D3 to induce CD11b and CD14 expression, likely by enhancing PU.1/c-jun and Sp1 transcriptional activity.

Enhancement of caffeic acid phenethyl ester on all-trans retinoic acid-induced differentiation in human leukemia HL-60 cells

All-trans retinoic acid (ATRA) induces complete remission in a high proportion of patients with acute promyelocytic leukemia (APL); however, the response is sometimes very slow. Furthermore, relapse and resistance to treatment often occur despite continued treatment with ATRA. Thereafter, combination treatment strategies have been suggested to circumvent these problems. The present study demonstrates that caffeic acid phenethyl ester (CAPE), a major component of honeybee propolis, enhanced ATRA-induced granulocytic differentiation in HL-60, a human promyelocytic cell line. The differentiation was assessed by Wright-Giemsa stain, nitroblue tetrazolium reduction, and membrane differentiation marker CD11b. In addition, CAPE enhanced ATRA-induced cell cycle arrest at the G1 phase by decreasing the association of cdk2-cyclin E complex. Finally, it was demonstrated that CAPE promoted the ATRA-mediated nuclear transcription activation of RARalpha assessed by EMSA assay and enhanced the expression of target genes including RARalpha, C/EBPepsilon, and p21 protein resulting in the differentiation development of leukemia. It is suggested that CAPE possesses the potential to enhance the efficiency of ATRA in the differentiation therapy of APL.

Synthesis of .GAMMA.-Hydroxybutenolides Applying Crossed Aldol Condensation in the Presence of a Bulky Lewis Acid and Their Anti-tumor Activity

An improved synthesis of gamma-hydroxybutenolides 1a-d was achieved via crossed aldol condensation between aldehydes 2a-d and the protected gamma-hydroxy-beta-methylbutenolides 3 or 4 using the bulky Lewis acid, aluminum tris(2,6-diphenylphenoxide) (ATPH). Using this same methodology, the gamma-hydroxybutenolides 17a-d having various heteroaromatic rings were synthesized and their anti-tumor activities were evaluated.

Cloning, characterization and mapping of porcine CD14 reveals a high conservation of mammalian CD14 structure, expression and locus organization

The cell surface protein CD14 plays a central role in innate immunity as a pattern recognition receptor. CD14 is part of a receptor complex also including toll-like receptor 4 and MD2 proteins. Binding of the ligand lipopolysaccharide to the complex on myeloid cells leads to release of pro-inflammatory cytokines and mediators from the cell. In this study, we present the cloning, characterization and tissue expression pattern of a porcine CD14 encoding cDNA, and the chromosomal localization of the porcine CD14 gene. The open reading frame is predicted to encode a protein of 373 amino acids, which shows conservation of structural as well as functional regions when compared to other mammalian species. The CD14 gene was localized to porcine chromosome 2 in a region syntenic to human chromosome 5q. Transcription analysis shows that CD14 is widely expressed in tissues examined in this study, which correlates well with expression primarily on myeloid cells.

Inhibition of dendritic cell generation and function by serum from prostate cancer patients: correlation with serum-free PSA

Tumor produces a number of immunosuppressive factors that block maturation of dendritic cells (DCs). Here, we demonstrated that endogenous factors presented in the serum of patients with prostate cancer (CaP) inhibited the generation of functionally active DCs from CD14+ monocytes in vitro. We have shown a significant inhibitory potential of serum obtained from patients with CaP and benign prostate hyperplasia benign prostatic hyperplasia (BPH) when compared with serum from healthy volunteers. As assessed by flow cytometry, expression of CD83, CD86, and CD40 molecules was strongly inhibited by CaP and BPH serum. In addition, these DCs were weak stimulators of allogeneic T cell proliferation when compared with DCs produced in the presence of healthy volunteer serum. Statistical analysis of the results revealed a positive relationship between the inhibition of expression of DC markers CD83 and CD80 and the levels of serum-free prostate-specific antigen (PSA). These data suggest that the DC system may be impaired in CaP patients.

Molecular cloning, chromosomal location, and expression analysis of porcine CD14

CD14 is a membrane-associated glycosylphosphatidylinositol (GPI)-anchored protein that binds lipopolysaccharide (LPS) of Gram-negative bacteria and enables LPS-dependent responses in a variety of cells. In this study a cDNA containing the porcine CD14 coding sequence has been cloned and its complete sequence determined. The amino acid sequence deduced from pig CD14 cDNA encodes a 373 amino acid polypeptide that exhibits 75%, 72%, 69%, 66%, 57% and 56% similarity to CD14 from cow, horse, human, rabbit, mouse and rat, respectively. Structural analysis showed that the porcine CD14 is a membrane glycoprotein with a GPI-anchor site and an extracellular domain containing 11 leucine-rich repeats. In addition, the LPS-binding regions identified in the human CD14 are highly conserved in the N-terminal domain of the porcine sequence. Fluorescence in situ hybridization was used to locate the CD14 gene on the pig chromosome 2, band q28. Expression analysis revealed that porcine CD14 transcripts were detected in all tissues and cells examined, suggesting that the expression of porcine CD14 gene is not restricted to myeloid cell lineage. Finally, we report that LPS stimulation significantly up-regulated CD14 gene expression in porcine alveolar macrophages.

Lung carcinomas decrease the number of monocytes/macrophages (CD14+ cells) that produce TNF-alpha

The role that inflammation plays in cancer is puzzling. In peripheral blood, TNF-alpha-producing monocytes (CD14+ cells) were compared among patients with lung cancer, patients with tuberculosis and healthy donors; also, in pleural effusion TNF-alpha-producing CD14+ cells were compared between tuberculous patients and lung cancer patients. To analyze the level of the cellular alteration in TNF-alpha production, an experimental model was set up. TNF-alpha-producing CD14+ cells in peripheral blood from lung cancer patients were significantly lower than those from healthy donors. In pleural effusion, TNF-alpha-producing CD14+ cells were significantly lower in lung cancer patients than in tuberculous patients. Based on the results obtained from an experimental model, we suggest that this phenomenon was attributed to a reduced expression of TNF-alpha transcript. These findings provide evidence that lung carcinomas reduce TNF-alpha production by macrophages, possibly by inducing in these cells an M2 phenotype, which favor tumor progression.

Transient Expression of Bone Morphogenic Protein-2 in Acute Liver Injury by Carbon Tetrachloride

Acute liver injury induced by administration of carbon tetrachloride (CCl4) was shown to be a model of wound-repair in rat liver. Albumin gene expression was significantly reduced at 24 h post injection with CCl4, but recovered at 48 h. We also observed significant and transient expression of bone morphogenic protein-2 (BMP-2) at 6-24 h post treatment. This expression was also shown with depletion of Kupffer cell by GdCl3, and immunostaining with anti-BMP-2 antibody showed BMP-2-producing cells interspersed in intralobular spaces of injured liver. These observations suggest that BMP-2 secreted from oval-like cells plays important roles in the wound healing response of injured liver.

The CD14+ CD16+ blood monocytes: their role in infection and inflammation

Blood monocyte subpopulations have been defined in man initially, and the two major types of monocytes are the CD14++ CD16- and the CD14+ CD16+ monocytes. These cells have been shown to exhibit distinct phenotype and function, and the CD14+ CD16+ were labeled proinflammatory based on higher expression of proinflammatory cytokines and higher potency in antigen presentation. The current review describes these properties, including the relationship to dendritic cells, and summarizes the host of publications about CD14+ CD16+ monocytes in inflammation and infectious disease in man, all of which suggest a crucial role of these cells in the disease processes. The review also covers the more recent description of homologues of these cells in other model species, which is expected to better define the role of monocyte subsets in disease.

Unique molecular characteristics of the environmental responses of mucosal macrophages

Macrophages are thought to be the cells that initially respond to environmental information and transmit this information to other immune cells. We hypothesize that there is a "network system" consisting of various tissue macrophages; the macrophages respond to stimulation and transmit secondary information to neighboring cells, which is important for the maintenance of homeostasis. Macrophages exist in all animal organs as tissue macrophages, and their cellular characteristics may change as an adaption to tissue-specific environments. It is believed that mucosal macrophages are particularly important in the macrophage network system because mucosa exist where there is regular exposure to foreign substances. However, the molecular mechanism by which intestinal mucosal macrophages respond to the external environment is not yet clear. In this review the biological characteristics of mucosal macrophages are introduced and how they recognize and eradicate various foreign substances is discussed.

Rhesus macaque polyclonal and monoclonal antibodies inhibit simian immunodeficiency virus in the presence of human or autologous rhesus effector cells

Although antibodies can prevent or modulate lentivirus infections in nonhuman primates, the biological functions of antibody responsible for such effects are not known. We sought to determine the role of antibody-dependent cell-mediated virus inhibition (ADCVI), an antibody function that inhibits virus yield from infected cells in the presence of Fc receptor-bearing effector cells, in preventing or controlling SIVmac251 infection in rhesus macaques (Macaca mulatta). Using CEMx174 cells infected with simian immunodeficiency virus mac251 (SIVmac251), both polyclonal and monoclonal anti-SIV antibodies were capable of potent virus inhibition in the presence of human peripheral blood mononuclear cell (PBMC) effector cells. In the absence of effector cells, virus inhibition was generally very poor. PBMCs from healthy rhesus macaques were also capable of mediating virus inhibition either against SIVmac251-infected CEMx174 cells or against infected, autologous rhesus target cells. We identified both CD14(+) cells and, to a lesser extent, CD8(+) cells as the effector cell population in the rhesus PBMCs. Finally, pooled, nonneutralizing SIV-antibody-positive serum, shown in a previous study to prevent infection of neonatal macaques after oral SIVmac251 challenge, had potent virus-inhibitory activity in the presence of effector cells; intact immunoglobulin G, rather than F(ab')(2), was required for such activity. This is the first demonstration of both humoral and cellular ADCVI functions in the macaque-SIV model. ADCVI activity in nonneutralizing serum that prevents SIV infection suggests that ADCVI may be a protective immune function. Finally, our data underscore the potential importance of Fc-Fc receptor interactions in mediating biological activities of antibody.

Antibiotics modulate the stimulated cytokine response to endotoxin in a human ex vivo, in vitro model

BACKGROUND

Sepsis may lead to the suppression of stimulated cytokine release after Gram-negative stimuli, correlating with a fatal outcome. Treatment of sepsis includes adequate therapy with antibiotics. The aim of this study was to investigate the role of antibiotics in the modulation of the lipopolysaccharide (LPS)-stimulated cytokine response of human monocytes.

METHODS

In this ex vivo, in vitro study, whole blood samples were taken from 10 healthy volunteers, stimulated with LPS in the presence or absence of various antibiotics (penicillin, amoxicillin, cefuroxime, ceftazidime, cefotaxime, piperacillin/tazobactam, imipenem/cilastatin, gentamicin, netilmicin, ciprofloxacin, vancomycin) and cultured for 24 h. Thereafter, tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) were measured in the supernatants by enzyme-linked immunosorbent assay (ELISA). Furthermore, CD14 and HLA-DR expression on monocytes was assessed using flow cytometry.

RESULTS

All cephalosporins decreased LPS-stimulated IL-10 release. Cefuroxime and cefotaxime also decreased the expression density of the LPS recognition molecule CD14 on monocytes. An increase in LPS-stimulated IL-10 release was observed with vancomycin. A suppression of LPS-stimulated TNF-alpha and IL-10 release was observed in the presence of ciprofloxacin.

CONCLUSION

These results indicate a modulation of the expression density of CD14 on monocytes, together with a shift from a balanced to an inflammatory cytokine release pattern, by cefuroxime and cefotaxime. Vancomycin changes the response to an anti-inflammatory release pattern. After ciprofloxacin, a profound unresponsiveness of immune-competent cells to LPS stimulation is observed. Because of the critical role of a balanced innate immune response, these data may be of importance for the selection of antibiotics in septic patients.

Increased Soluble 4-1BB Ligand (4-1BBL) Levels in Peripheral Blood of Patients with Multiple Sclerosis

4-1BB ligand (4-1BBL; CD137L) is a member of the tumour necrosis factor superfamily expressed primarily on antigen presenting cells such as B cells, macrophages and dendritic cells. Its engagement with the receptor 4-1BB (CD137) has been shown to promote T-cell activation and regulate proliferation and survival of T cells. The role of the costimulatory molecule in multiple sclerosis (MS) remains unclear. In this study, the expression of 4-1BBL and soluble 4-1BBL (s4-1BBL) protein levels were analysed in peripheral blood of MS patients. Compared with healthy controls, MS patients had an increase in both plasma s4-1BBL protein levels and expression of 4-1BBL in CD14(+) monocytes. In contrast, myelin basic protein-reactive T-cell proliferation was not found to be inhibited by the use of an anti-4-1BBL antibody. The elevated s4-1BBL protein levels in the MS patients may function as a self-regulatory mechanism of 4-1BB/4-1BBL interaction and costimulation.

Polymorphisms of the CD14 gene and atopic phenotypes in Czech patients with IgE-mediated allergy

IgE-mediated allergy is a common chronic disorder resulting from interactions between genetic and environmental factors. The gene encoding CD14 is a positional candidate gene for allergic diseases as it is localised on chromosome 5q31.1, a region linked to asthma and bronchial hyperresponsiveness. We investigated the relationship among atopic phenotypes and six polymorphisms in the CD14 gene. Polymerase chain reaction with RFLP analyses was used to determine the CD14 genotypes in subjects with IgE-mediated allergic diseases (n=282) and random controls (n=187). No significant differences in allele or genotype frequencies for individual polymorphisms between patients and controls were found. However, when atopic patients were subdivided into subjects with positive and with negative skin prick tests for separate antigens, T allele of the 1341G/T polymorphism was significantly associated with positive reactivity to mites (P=0.007) and moulds (P=0.041). Similarly, the C allele frequency of the -159C/T variant was increased in patients with positive skin prick tests for mites (P=0.046) and moulds (P=0.056). In haplotype analysis, the common -1619A/-1359G/-550C/-159C/+1188G/+1341T haplotype was associated with positive reaction to these antigens (P values: 0.0008-0.0035). Our study supports the idea that CD14 plays a role in IgE-mediated allergic diseases, and its gene polymorphisms can be important for manifestation of these disorders.

[Effects of Qinggan Huoxue Recipe and its decomposed formulas on CD14, Toll like receptor 4 and nuclear factor-kappaB expressed by Kupffer cells]

OBJECTIVE

To investigate the effects of Qinggan Huoxue Recipe (QGHXR), a compound Chinese herbal medicine, and its decomposed formulas Qinggan Recipe (QGR) and Huoxue Recipe (HXR) on expressions of CD14, Toll like receptor 4 (TLR(4)) and nuclear factor-kappaB (NF-kappaB) in Kupffer cells.

METHODS

The isolated primary rat Kupffer cells were treated with lipopolysaccharide (LPS) for a certain period of time, a series of concentrations of drug-containing serums of QGHXR and its decomposed formulas were added, the expressions of NF-kappaB, tumor necrosis factor-alpha (TNF-alpha), CD14, and TLR(4) of the Kupffer cells were detected in different culture conditions by using Western blot, real-time reverse transcription polymerase chain reaction (RT-PCR) and ELISA methods respectively.

RESULTS

QGR could down-regulate the expression of membrane receptor CD14, but the expression of NF-kappaB and TNF-alpha were not significantly decreased after QGR treatment. HXR could down-regulate the expression of membrane receptor TLR4 and inhibit the expressions of NF-kappaB and TNF-alpha. QGHXR could down regulate the expressions of membrane receptors CD14 and TLR(4) and inhibit the expressions of NF-kappaB and TNF-alpha.

CONCLUSION

QGHXR can protect liver cells by down regulating the expressions of CD14, TLR(4) and NF-kappaB and inhibiting TNF-alpha expression.

Induction of differentiation in leukemic cell strains with myelopeptide-4

We studied the capacity of myelopeptide-4 (regulatory peptide of the bone marrow origin) to induce terminal differentiation of HL-60 and K-562 leukemic cells. Myelopeptide-4 increased the expression of CD14 and CD38 differentiation antigens on the surface of HL-60 cells and of CD44 antigen on K-562 cells, induced the appearance of mature monocyte/macrophages in HL-60 culture and hemoglobin-producing cells in K-562 cell culture, and stimulated phagocytic activity of THP-1 leukemic cells. Myelopeptide-4 is an endogenous factor of cell differentiation, a prospective agent for antileukemic therapy.

GM-CSF regulates a PU.1-dependent transcriptional program determining the pulmonary response to LPS

Alveolar macrophages (AMs) normally respond to lipopolysaccharide (LPS) by activating Toll-like receptor (TLR)-4 signaling, a mechanism critical to lung host defense against gram-negative bacteria such as Pseudomonas aeruginosa. Because granulocyte macrophage colony-stimulating factor (GM-CSF)-deficient (GM(-/-)) mice are hyporesponsive to LPS, we evaluated the role of GM-CSF in TLR-4 signaling in AMs. Pulmonary TNF-alpha levels and neutrophil recruitment 4 h after intratracheal administration of Pseudomonas LPS were reduced in GM(-/-) compared with wild-type (GM(+/+)) mice. Secretion of TNF-alpha by AMs exposed to LPS ex vivo was also reduced in GM(-/-) mice and restored in mice expressing GM-CSF specifically in the lungs (SPC-GM(+/+)/GM(-/-) mice). LPS-dependent NF-kappaB promoter activity, TNF-alpha secretion, and neutrophil chemokine release were reduced in AM cell lines derived from GM(-/-) mice (mAM) compared with GM(+/+) (MH-S). Retroviral expression of PU.1 in mAM cells, which normally lack PU.1, rescued all of these AM defects. To determine whether GM-CSF, via PU.1, regulated expression of TLR-4 pathway components, mRNA and protein levels for key components were evaluated in MH-S cells (GM(+/+), PU.1(Positive)), mAM cells (GM(-/-), PU.1(Negative)), and mAMPU.1+ cells (GM(-/-), PU.1(Positive)). Cluster of differentiation antigen-14, radioprotective 105, IL-1 receptor-associated kinase (IRAK)-M mRNA, and protein were dependent upon GM-CSF and restored by expression of PU.1. In contrast, expression of other TLR-4 pathway components (myeloid differentiation-2, TLR-4, IRAK-1, IRAK-2, Toll/IL-1 receptor domain containing adapter protein/MyD88 adaptor-like, myeloid differentiation primary-response protein 88, IRAK-4, TNF receptor-associated factor-6, NF-kappaB, inhibitor of NF-kappaB kinase) were not GM-CSF or PU.1-dependent. These results show that GM-CSF, via PU.1, enables AM responses to P. aeruginosa LPS by regulating expression of a specific subset of components of the TLR-4 signaling pathway.

Erythroid cells play essential roles in angiogenesis by bone marrow cell implantation

Bone marrow cell implantation (BMI) has been utilized to treat patients with limb and heart ischemia. BMI provides angiogenic precursors and angiogenic cytokine-producing cells, especially erythroid cells. In this study, we induced in vitro angiogenesis cultures and in vivo BMI simulation using a murine limb ischemia model to examine the role of erythroid cells and the effect of erythropoietin (EPO). Human erythroid colonies (BFU-e) induced capillary networks around the colonies in vitro. Erythroid cells in human bone marrow produced vascular endothelial growth factor and placental growth factor. The angiogenic effects of erythroid cells were further amplified in the presence of EPO. Limb-ischemic mice were treated with BMI +/- EPO, and limb survival, blood flow recovery, and muscle histology were analyzed. Treatment with whole bone marrow cells + EPO significantly improved limb survival and blood flow. The cumulative effects of EPO on BMI induced and increase in capillary number and artery enlargement. Erythroid cells were essential for the in vivo effects of BMI, and CD14-positive cells supported the biological effects. In addition to the direct effect of EPO on angiogenesis, EPO showed indirect effect on angiogenesis through amplifying the angiogenic effects by erythroid cells supported by CD14-positive cells.

An α-Glucan of Pseudallescheria boydii Is Involved in Fungal Phagocytosis and Toll-like Receptor Activation

The host response to fungi is in part dependent on activation of evolutionarily conserved receptors, including toll-like receptors and phagocytic receptors. However, the molecular nature of fungal ligands responsible for this activation is largely unknown. Herein, we describe the isolation and structural characterization of an alpha-glucan from Pseudallescheria boydii cell wall and evaluate its role in the induction of innate immune response. These analyses indicate that alpha-glucan of P. boydii is a glycogen-like polysaccharide consisting of linear 4-linked alpha-D-Glcp residues substituted at position 6 with alpha-D-Glcp branches. Soluble alpha-glucan, but not beta-glucan, led to a dose-dependent inhibition of conidia phagocytosis. Furthermore, a significant decrease in the phagocytic index occurred when alpha-glucan from conidial surface was removed by enzymatic treatment with alpha-amyloglucosidase, thus indicating an essential role of alpha-glucan in P. boydii internalization by macrophages. alpha-Glucan stimulates the secretion of inflammatory cytokines by macrophages and dendritic cells; again this effect is abolished by treatment with alpha-amyloglucosidase. Finally, alpha-glucan induces cytokine secretion by cells of the innate immune system in a mechanism involving toll-like receptor 2, CD14, and MyD88. These results might have relevance in the context of infections with P. boydii and other fungi, and alpha-glucan could be a target for intervention during fungal infections.

Lipopolysaccharide-induced decreased protein S expression in liver cells is mediated by MEK/ERK signaling and NFkappaB activation: involvement of membrane-bound CD14 and toll-like receptor-4

BACKGROUND

The vitamin K-dependent protein S (PS), mainly synthesized in hepatocytes and endothelial cells, plays a critical role in the anticoagulant activity of plasma. The decreased plasma level of PS in sepsis is associated with thrombotic tendency, but the mechanism is unclear.

OBJECTIVES

In the present study, we examined the effect of lipopolysaccharide (LPS) on PS expression in vivo in rat liver, and in vitro in isolated hepatocytes and sinusoidal endothelial cells (SECs) from normal rats.

RESULTS

LPS induced a progressive decrease of plasma PS antigen level up to 12 h with a slight recovery at 24 h, and a transient decrease of liver PS mRNA level at 4-8 h with a complete recovery at 24 h. In the in vitro studies, LPS decreased PS antigen and mRNA levels in both hepatocytes and SECs. After LPS treatment, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and interferon-gamma (IFN-gamma) transiently increased in plasma. IL-6 increased the protein expression of PS from hepatocytes, while TNF-alpha decreased it from SECs. LPS increased CD14 in hepatocytes and decreased it in SECs, but did not affect toll-like receptor-4 (TLR-4) expression in both cells. Antirat CD14 and antirat TLR-4 antibodies inhibited LPS-induced NFkappaB activation, and a NFkappaB inhibitor suppressed LPS-induced decreased PS expression in both cells. Furthermore, MEK inhibitor blocked LPS-induced decreased PS expression in both cells.

CONCLUSIONS

These findings suggest that LPS-induced decreased PS expression in hepatocytes and SECs is mediated by MEK/ERK signaling and NFkappaB activation and that membrane-bound CD14 and TLR-4 are involved in this mechanism. These findings may explain in part the decreased level of plasma PS and thrombotic tendency in sepsis.

HIV-1 protease inhibitor ritonavir potentiates the effect of 1,25-dihydroxyvitamin D3 to induce growth arrest and differentiation of human myeloid leukemia cells via down-regulation of CYP24

HIV-1 protease inhibitor, ritonavir (RTV) is a potent inhibitor of cytochrome p450 (CYPs) enzymes. This study explored the effects of RTV on CYP24 which converts 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] to its inactive form 1,24,25,(OH)(3). Real-time RT-PCR showed that exposure of HL-60 cells to 1,25(OH)(2)D(3) induced expression of CYP24, and pre-incubation of these cells with RTV decreased this transcripts, resulting in increased intracellular levels of 1,25(OH)(2)D(3) and potentiation of the ability of 1,25(OH)(2)D(3) to induce growth arrest and differentiation of these cells. Taken together, inhibition of CYP24 might open a new paradigm for therapy using Vitamin D compounds.

Functional and phenotypic changes in monocytes from patients with tuberculosis are reversed with treatment

Alterations of monocyte/macrophages have been reported in patients with tuberculosis (TB), but their significance is poorly understood. Blood mononuclear cells from patients with different clinical forms of TB, at various times of anti-TB treatment, and healthy tuberculin positive individuals, were double-stained for CD14 plus CD206, TLR-2, IFN-gammaR1, CD40, HLA-DR, CD36 and CD163, and analyzed by flow cytometry. Monocytes were infected with Mycobacterium tuberculosis H37Rv and 24h later the phenotype, induction of necrosis and apoptosis and production of tumor necrosis factor TNFalpha, interleukin (IL)-10 and IL-12p40 were determined. TB patients presented higher percentage of CD14+ cells but lower percentage of CD14+DR+ and CD14+CD36+ cells. Expression of CD14, HLA-DR and CD36 was decreased in TB patients. Normal percentages and expression were restored during anti-TB treatment. Monocytes from TB patients underwent necrosis and apoptosis after M. tuberculosis infection, whereas monocytes from healthy controls exhibited only apoptosis. Anti-TB treatment reverted necrosis. There were no differences between the various clinical forms of TB. In vitro M. tuberculosis infection decreased expression of the membrane molecules studied. HLA-DR and CD36 inhibition correlated with induction of apoptosis. Restoration of monocyte alterations during anti-TB treatment suggests that such alterations may be caused by the high M. tuberculosis load present during active disease.

A postmigrational switch among skin-derived dendritic cells to a macrophage-like phenotype is predetermined by the intracutaneous cytokine balance

Migration of dendritic cells (DC) to secondary lymphoid organs under proinflammatory conditions coincides with their maturation and acquisition of T cell stimulatory abilities. In contrast, impaired activation of DC, e.g., in tumor-conditioned environments, may hamper their activation and possibly their subsequent migration to lymph nodes, leading to either immunological tolerance or ignorance, respectively. In this study, the influence of cytokines in the peripheral skin microenvironment on the activation state of migrating cutaneous DC was assessed using an ex vivo human skin explant model. We observed a phenotypic shift from mature CD83(+) DC to immature CD14(+) macrophage-like cells within 7 days subsequent to migration from unconditioned skin. These macrophage-like cells displayed a poor T cell stimulatory ability and lacked expression of CCR7, thus precluding their migration to paracortical T cell areas in the lymph nodes. The balance of suppressive and stimulatory cytokines during the initiation of migration decided the postmigrational fate of DC with IL-10 accelerating and GM-CSF and IL-4 preventing the phenotypic switch, which proved irreversible once established. These observations indicate that, in immunosuppressed environments, a postmigrational DC-to-macrophage shift may hinder T cell activation, but also that it may be prevented by prior conditioning of the tissue microenvironment by GM-CSF and/or IL-4.

Intracellular monocyte cytokine production and CD 14 expression are up-regulated in severe vs mild chronic heart failure

BACKGROUND

The role of circulating monocytes in the process of low-grade inflammation, characteristic of chronic heart failure (CHF), has recently been questioned. Lipopolysaccharide (LPS) desensitization has been proposed to mediate reduced monocyte cytokine elaboration in patients with severe CHF.

METHODS

Intracellular monocyte production of interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6) and tumor necrosis factor (TNF)-alpha, and monocyte CD 14 expression were measured flow-cytometrically without and after 8-hour LPS stimulation in 46 patients with CHF and in a healthy control group.

RESULTS

Basal cytokine concentrations were similar for the control and the mild CHF groups (New York Heart Association [NYHA] Class I or II). After LPS stimulation, IL-6 (p=0.002) and TNF-alpha levels (p=0.001) were lower in the latter group, whereas IL-1 beta production was comparable. For the moderate-severe CHF patients, unstimulated IL-1 beta (p=0.04) was higher, whereas IL-6 (p=0.2) and TNF-alpha (p=0.1) levels were not different from the controls. Measurement of LPS-stimulated cytokine production showed no differences between the control group and patients with moderate-severe CHF (all p= 0.5). Upon comparing mild vs moderate-severe CHF patients, higher levels of unstimulated cytokine production (IL-1 beta, p=0.002; IL-6, p=0.01; TNF-alpha, p=0.003), stimulated IL-1 beta (p=0.002) and IL-6 (p=0.008) were found in the latter patients. CD 14 expression in the moderate-severe CHF group was higher than in the mild-CHF group (p = 0.03) and was strongly related to stimulated IL-1 beta (r=0.62, p<0.0001), IL-6 (r=0.56, p=0.0002) and TNF-alpha (r=0.41, p=0.006) production.

CONCLUSIONS

CD 14 expression and monocyte cytokine production, both unstimulated and after LPS stimulation, are increased in moderate-severe CHF when compared with mild CHF. These data suggest that circulating monocytes, possibly via increased CD 14 expression, may play a significant role in the immunologic dysbalance observed in advanced CHF.

Role of Toll-like receptor 4 for the pathogenesis of acute lung injury in Gram-negative sepsis

BACKGROUND AND OBJECTIVE

Proinflammatory cytokines as well as nitric oxide (NO) play a major role in mediating the response to lipopolysaccharide (LPS). The present study tested the hypothesis that LPS induces proinflammatory cytokines in the lung via the Toll-like receptor 4 (TLR4)/CD14 signalling cascade.

METHODS

Control mice and TLR4-deficient (TLR4-D) mice were used to test TLR4-mediated effects of LPS. Both strains received either Escherichia coli LPS (20 mg kg-1 intraperitoneal) or saline and their lungs were collected at different time points. Pulmonary nuclear factor kappaB (NFkappaB) activation was investigated with electromobility shift assay. mRNA expression of inflammatory mediators and their corresponding receptors were detected with Ribonuclease Protection Assay. Protein expression was detected by ELISA and western blotting. Inducible NO synthase (iNOS) expression was monitored by RT-PCR and iNOS activity by conversion of l-arginine to citrulline. Immune cells were sampled by bronchoalveolar lavage (BAL) and classified.

RESULTS

LPS application induced CD14-, but not TLR4 protein expression in control mice. Activation of pulmonary NFkappaB was observed within 60 min in control, but not in TLR4-D mice. Six hours of LPS administration induced a significant increase in pulmonary tumour necrosis factor alpha-, interleukin-1beta- and interleukin-6 mRNA and protein expression in control mice compared to TLR4-D mice. Furthermore, LPS induced a significantly higher increase of the iNOS expression and catalytic activity in control mice than in TLR4-D mice. BAL revealed an increase in total cell count in all LPS treated mice.

CONCLUSION

Our findings suggest that TLR4 plays a key role for regulating the expression of relevant cytokines within the lung during endotoxic shock.

Wolbachia Endosymbiotic Bacteria of Brugia malayi Mediate Macrophage Tolerance to TLR- and CD40-Specific Stimuli in a MyD88/TLR2-Dependent Manner

Lymphatic filarial nematodes are able to down-regulate parasite-specific and nonspecific responses of lymphocytes and APC. Lymphatic filariae are reliant on Wolbachia endosymbiotic bacteria for development and survival. We tested the hypothesis that repeated exposure to Wolbachia endosymbionts would drive macrophage tolerance in vitro and in vivo. We pre-exposed murine peritoneal-elicited macrophages to soluble extracts of Brugia malayi female worms (BMFE) before restimulating with BMFE or TLR agonists. BMFE tolerized macrophages (in terms of IFN-beta, IL-1beta, IL-6, IL-12p40, and TNF-alpha inflammatory cytokine production) in a dose-dependent manner toward self, LPS, MyD88-dependent TLR2 or TLR9 ligands (peptidoglycan, triacyl lipopeptide, CpG DNA) and the MyD88-independent/TRIF-dependent TLR3 ligand, polyinosinic-polycytidylic acid. This was accompanied with down-regulation in surface expression of TLR4 and up-regulation of CD14, CD40, and TLR2. BMFE tolerance extended to CD40 activation in vitro and systemic inflammation following lethal challenge in an in vivo model of endotoxin shock. The mechanism of BMFE-mediated macrophage tolerance was dependent on MyD88 and TLR2 but not TLR4. Evidence that desensitization was driven by Wolbachia-specific ligands was determined by use of extracts from Wolbachia-depleted B. malayi, aposymbiotic filarial species, and a cell line stably infected with Wolbachia pipientis. Our data promote a role for Wolbachia in contributing toward the dysregulated and tolerized immunological phenotype that accompanies the majority of human filarial infections.

[The influence of CD14 genomic polymorphism on CD14 gene expression as well as protein release and its clinical significance in patients with extensive burns]

OBJECTIVE

To investigate the influence of a lipopolysaccharide receptor CD14-159C/T genomic polymorphism on CD14 gene expression as well as protein release, and the relation of sepsis susceptibility and prognosis in patients with extensive burns.

METHODS

The study group consisted of 26 patients with burns covering more than 30% of the total body surface area. The CD14 gene polymorphism was determined by polymerase chain reaction (PCR) and subsequent HaeIII restriction enzyme digestion of the PCR products. Meanwhile, the association of CD14, TNF-alpha mRNA expression in leukocytes and soluble CD14 (sCD14) levels in serum with CD14-159 polymorphism as well as prognosis after burns was also studied.

RESULTS

The T allele frequencies in sepsis patients and non-survivors were higher than those in non-septic patients and survivors. The levels of CD14 mRNA, TNF-alpha mRNA expression and serum sCD14 were significantly different among patient groups with TT, TC, and CC genotypes. The above differences were also existed between survivors and non-survivors. CD14 mRNA expression was higher in heterozygotes (TT and TC) than in C homozygous patients (P < 0.05 or P < 0.01), and sCD14 level was higher in heterozygotes (TC) than C homozygous patients on day 7 postburn (P < 0.05). During the 28-day observation period, mean TNF-alpha mRNA expression was higher in patients homozygous for T allele than C homozygotes (P < 0.05). In addition, higher CD14 mRNA values were found in non-survivors compared to those in survivors on days 7 and 28 postburn (P < 0.05).

CONCLUSIONS

CD14C-159T polymorphism might markedly influence CD14 mRNA expression and sCD14 levels, and it seems to be associated with sepsis susceptibility and prognosis in patients with extensive burns. The T allele could be a genetic risk marker of adverse prognosis.