Circulating levels of the long pentraxin PTX3 correlate with severity of infection in critically ill patients

OBJECTIVE

To evaluate the recently discovered long pentraxin PTX3 in plasma of critically ill patients and to compare it with the classic short pentraxin C-reactive protein and with other indicators of inflammation.

DESIGN

A cohort study on plasma samples.

SETTING

Medical intensive care unit (ICU) of the University Hospital of Basel.

PATIENTS

A total of 101 consecutive critically ill patients admitted to the medical ICU.

INTERVENTIONS

Venous blood samples were routinely obtained at entry, on day 2, and at discharge or before death.

MEASUREMENTS AND MAIN RESULTS

Plasma samples were obtained from 101 consecutive critically ill patients admitted to the ICU with systemic inflammatory response syndrome, sepsis, or septic shock. PTX3 plasma levels were measured by enzyme-linked immunosorbent assay. PTX3 was elevated in critically ill patients, with a gradient from systemic inflammatory response syndrome to septic shock. PTX3 levels correlated with clinical scores reflecting severity of disease (e.g., Acute Physiology and Chronic Health Evaluation II: p =.00097). In addition, high levels of PTX3 were associated with unfavorable outcome.

CONCLUSIONS

The long pentraxin PTX3 is elevated in critically ill patients and correlates with severity of disease and infection. Compared with the short pentraxin C-reactive protein, PTX3 may be a more direct indicator of tissue involvement by inflammatory and infectious processes.

The LPS receptor (CD14) links innate immunity with Alzheimer's disease

To rapidly respond to invading microorganisms, humans call on their innate immune system. This occurs by microbe-detecting receptors, such as CD14, that activate immune cells to eliminate the pathogens. Here, we link the lipopolysaccharide receptor CD14 with Alzheimer's disease, a severe neurodegenerative disease resulting in dementia. We demonstrate that this key innate immunity receptor interacts with fibrils of Alzheimer amyloid peptide. Neutralization with antibodies against CD14 and genetic deficiency for this receptor significantly reduced amyloid peptide induced microglial activation and microglial toxicity. The observation of strongly enhanced microglial expression of the LPS receptor in brains of animal models of Alzheimer's disease indicates a clinical relevance of these findings. These data suggest that CD14 may significantly contribute to the overall neuroinflammatory response to amyloid peptide, highlighting the possibility that the enormous progress currently being made in the field of innate immunity could be extended to research on Alzheimer's disease.

Human monocyte CD14 is upregulated by lipopolysaccharide

Membrane CD14 is involved in lipopolysaccharide (LPS)-induced monocyte activation; it binds LPS, and antibodies against CD14 block the effects of low-dose LPS. It is unknown how LPS regulates its own receptor CD14 in vitro. Therefore, we investigated the effects of LPS on CD14 mRNA and membrane and soluble CD14 (mCD14 and sCD14, respectively) in human monocytes and macrophages. No changes were observed during the first 3 h of LPS stimulation. After 6 to 15 h, LPS weakly reduced CD14 mRNA and mCD14 and transiently enhanced sCD14 release. A 2-day incubation with LPS caused increases in the levels of CD14 mRNA (2-fold), mCD14 (2-fold), sCD14 (1.5-fold), and LPS-fluorescein isothiocyanate binding (1.5-fold); a 5-h incubation with LPS was sufficient to induce the late effects on mCD14 and sCD14. The maximal effect on mCD14 and sCD14 was reached with > or = 1 ng of LPS per ml; the proportional distribution of the two sCD14 isoforms was not modified by LPS. Besides rough and smooth LPS, lipid A, heat-killed Escherichia coli, lipoteichoic acid, and Staphylococcus aureus cell wall extract (10 micrograms/ml) caused similar increases of mCD14. The LPS effect was blocked by polymyxin B but not by anti-tumor necrosis factor alpha, anti-interleukin-6, anti-gamma interferon, and anti-LPS-binding protein. LPS-induced tumor necrosis factor alpha production was abolished after a second 4-h challenge. In contrast, the LPS-induced increases CD14 mRNA, mCD14, and sCD14 were stronger and appeared earlier after a second LPS challenge. In conclusion, CD14 is transcriptionally upregulated by LPS and other bacterial cell wall constituents.

Molecular and cellular permeability control at the blood-brain barrier

The blood-brain barrier (BBB) is formed by brain capillary endothelial cells. These cells have at least three properties which distinguish them from their peripheral counterparts: (1) tight junctions (TJs) of extremely low permeability; (2) low rates of fluid-phase endocytosis; (3) specific transport and carrier molecules. In combination, these features restrict the nonspecific flux of ions, proteins, and other substances into the central nervous system (CNS) environment. The restriction protects neurons from harmful compositional fluctuations occurring in the blood and allows uptake of essential molecules. Breakdown of the BBB is associated with a variety of CNS disorders and results in aggravation of the condition. Restoration of the BBB is thus one strategy during therapy of CNS diseases. Its success depends on a precise knowledge of the structural and functional principles underlying BBB functionality. In this review we have tried to summarise the current knowledge of TJs, including information gained from non-neuronal systems, and describe selected mechanisms involved in permeability regulation.

Increased circulating soluble CD14 is associated with high mortality in gram-negative septic shock

The soluble glycoprotein sCD14 binds lipopolysaccharide, a complex that activates endothelial cells and that may be crucial in gram-negative sepsis. Therefore, serum sCD14 was analyzed in 54 patients with gram-negative septic shock and in 26 healthy controls. sCD14 was tested by ELISA and Western blotting. Patients had higher sCD14 concentrations than controls (median, 3.23 vs. 2.48 micrograms/mL, P = .002). Increased levels were associated with high mortality (median, 4.2 micrograms/mL in nonsurvivors vs. 2.8 micrograms/mL in survivors, P = .001). sCD14 was found in two isoforms (49 and 55 kDa) in monocyte cultures. In sera only one of either form was detectable. Controls had the 49-kDa form, and patients had either the 49- or 55-kDa form, but patients with high levels of sCD14 had only the 55-kDa form. Twenty-one (53%) of 39 with the 55-kDa form and 8 (57%) of 14 with the 49-kDa form died. Thus, the level of sCD14 but not its biochemical form had a prognostic value in patients with gram-negative septic shock.

CD14, new aspects of ligand and signal diversity

The glycosyl-phosphatidylinositol-linked glycoprotein CD14 is expressed in myeloid cells and serum. It binds Gram-negative and -positive bacterial cell wall components and endogenous phospholipids. Toll-like receptors, NF-kappaB and MAP kinases participate in CD14 signaling of inflammation. Alterations of CD14 in inflammatory diseases support a pathogenic role for this microbial receptor.

Function of soluble CD14 in serum from patients with septic shock

Soluble CD14 (sCD14) mediates lipopolysaccharide (LPS) activation of epithelial cells in vitro and may thereby be harmful in sepsis. sCD14 function was analyzed in sera from 62 patients with septic shock and compared with data from appropriate controls. sCD14 function was measured as sCD14-dependent LPS-induced interleukin (IL)-8 release in the SW620 epithelial cell line. In these cells, IL-8 production correlated with LPS concentration and the amount of sCD14. The effect of natural recombinant sCD14 was maximal at 100 ng/mL and blocked by anti-CD14 antibodies. Patient and control sera (0.5% final concentration) promoted induction of IL-8 by 100 ng/mL LPS in SW620 cells. In sepsis patients (highest serum sCD14), values were significantly higher than in the other groups. The LPS-induced IL-8 response was blocked by anti-CD14 and correlated with the serum CD14 level in sepsis patients. Thus, sCD14 could play a pathogenic role in sepsis.

Effect of cytokines and lipopolysaccharide on CD14 antigen expression in human monocytes and macrophages

The 52 kD myeloid membrane glycoprotein CD14 represents the receptor for complexes of lipopolysaccharide (LPS) and LPS binding protein (LBP); it is involved in LPS induced tumor necrosis factor-alpha production. Expression of CD14 increases in monocytes differentiating into macrophages, and it is reduced by rIFNg in monocytes in vitro. In the present study CD14 membrane antigen expression was investigated in cultures of human mononuclear leucocytes (PBL), in elutriated, purified monocytes, and in blood monocyte derived Teflon cultured macrophages. Cells were incubated for 15 or 45 h with rIL-1, rIL-2, rIL-3, rIL-5, rIL-6, rTNFa, rGM-CSF, rM-CSF, rTGFb1, rIFNa, lipopolysaccharide (LPS), and, as a control, rIFNg. The monoclonal antibodies Leu-M3 and MEM 18 were used for labelling of CD14 antigen by indirect immunofluorescence and FACS analysis of scatter gated monocytes or macrophages. IFNg concentrations were determined in PBL culture supernatants by ELISA. rIFNa and rIL-2 reduced CD14 in 15 and 45 h PBL cultures, an effect mediated by endogenous IFNg, since it was abolished by simultaneous addition of an anti-IFNg antibody. rIFNa and rIL-2 were ineffective in purified monocytes or macrophages. rIL-4 strongly reduced CD14 in PBL and purified monocytes after 45 h, whereas in macrophages the decrease was weak, although measurable after 15 h. The other cytokines investigated did not change CD14 antigen expression. Cycloheximide alone reduced CD14, but when added in combination with rIFNg the effect on CD14 downregulation was more pronounced. The effect of rIFNg on CD14 in PBL cultures was dose-dependently inhibited by rIL-4 and this inhibition is probably due to an IL-4 mediated blockade of IFNg secretion. LPS at a low dose increased CD14, at a high dose it produced a variable decrease of CD14 in PBL, which was probably due to LPS induced IFNg secretion. LPS strongly enhanced CD14 in 45 h cultures of purified monocytes. The results, showing that CD14 antigen expression is upregulated by LPS and downregulated by rIFNg and rIL-4, suggest that the LPS-LBP receptor is involved in the feedback response of IFNg and IL-4 to LPS stimulation.

In vivo survival of teicoplanin-resistant Staphylococcus aureus and fitness cost of teicoplanin resistance

Glycopeptide resistance, in a set of in vitro step-selected teicoplanin-resistant mutants derived from susceptible Staphylococcus aureus SA113, was associated with slower growth, thickening of the bacterial cell wall, increased N-acetylglucosamine incorporation, and decreased hemolysis. Differential transcriptome analysis showed that as resistance increased, some virulence-associated genes became downregulated. In a mouse tissue cage infection model, an inoculum of 10(4) CFU of strain SA113 rapidly produced a high-bacterial-load infection, which triggered MIP-2 release, leukocyte infiltration, and reduced leukocyte viability. In contrast, with the same inoculum of the isogenic glycopeptide-resistant derivative NM67, CFU initially decreased, resulting in the elimination of the mutant in three out of seven cages. In the four cages in which NM67 survived, it partially regained wild-type characteristics, including thinning of the cell wall, reduced N-acetylglucosamine uptake, and increased hemolysis; however, the survivors also became teicoplanin hypersusceptible. The elimination of the teicoplanin-resistant mutants and selection of teicoplanin-hypersusceptible survivors in the tissue cages indicated that glycopeptide resistance imposes a fitness burden on S. aureus and is selected against in vivo, with restoration of fitness incurring the price of resistance loss.

Plasma catecholamines and cardiac, renal and peripheral vascular adrenoceptor-mediated responses in different age groups of normal and hypertensive subjects

The role of the sympathetic nervous system in cardiac, renal and peripheral vascular adrenoceptor-mediated responses was investigated in patients with essential hypertension and age-matched normotensive subjects. Regardless of age plasma adrenaline was significantly higher in hypertensive when compared with normotensive subjects. This suggests a sympatho-adrenal factor in essential hypertension. Plasma noradrenaline tended to increase with age but its similarity between normotensive and hypertensive subjects points to similar postganglionic neural activity and/or similar overflow of noradrenaline into the circulation. On the other hand, beta-adrenoceptor-mediated tachycardia in response to exercise and intravenous isoproterenol as well as the forearm vasodilator response to intraarterial isoproterenol decreased in normal subjects with older age. In hypertensives this age-dependent beta-receptor-related effect tends to be enhanced as judged from the greater reduction of cardiac isoproterenol sensitivity and the blunted renin response to exercise stimulation. The dilator response to alpha-adrenoceptor blockade with phentolamine was not different in both groups. Therefore a qualitative rather than quantitative derangement of sympathetic control of vascular resistance - in which beta-dilator effects are reduced and alpha-constrictor mechanisms prevail - may contribute to the maintenance of established hypertension.

Role of lipopolysaccharide susceptibility in the innate immune response to Salmonella typhimurium infection: LPS, a primary target for recognition of Gram-negative bacteria

Lipopolysaccharide is an important recognition marker by virtue of which the innate immune system senses and reacts against Gram-negative bacteria invading the LPS susceptible host. This review deals with the factors affecting LPS susceptibility and with the role of the latter in the course and outcome of Salmonella typhimurium infection.

LPS directly induces oxygen radical production in human monocytes via LPS binding protein and CD14

In human monocytes, superoxide (O2-) generation accompanies phagocytosis and is important for bactericidal activity. It also contributes to tissue damage in inflammation. In the present study we investigated, whether lipopolysaccharide (LPS) directly stimulates monocyte O2- production with kinetics known for other LPS effects and, if so, by which mechanism. LPS caused a time- and dose-dependent O2- release in nonadherent purified monocytes. The effect appeared after 5 min, peaked at 30 min, and disappeared after 2 h. It was maximal with 10 ng/ml lipid A (+148 +/- 22%, P < .001), 1 ng/ml LPS Escherichia coli Re (+226 +/- 68%, P < .001), and 100 ng/ml LPS Salmonella abortus equi sm (+272 +/- 52%, P < .001), respectively. The effect was not observed in buffer, even when using 10 micrograms/ml LPS. It was dependent on the presence of heat-inactivated AB serum, with a maximal effect at > or = 0.5%. Serum could be replaced by LPS-binding protein (LBP). Polymyxin B and anti-LBP antiserum, respectively, blocked the LPS effect. LPS-induced O2- generation was also completely blocked by anti-CD14 antibodies (3C10 and 63D3) and by their corresponding F(ab')2 fragments. Monocytes treated with phosphoinositol-specific phospholipase C and monocytes from patients with paroxysmal nocturnal hemoglobinuria, lacking the phosphatidylinositol-anchored CD14, did not respond to LPS stimulation with O2- production. Similarly to LPS, E. coli caused stronger O2- production with heat-inactivated serum than without, and this effect was blocked by anti-CD14 antibodies. In conclusion, these data indicate that LPS directly stimulates O2- production in human monocytes via CD14 depending on LBP.

Human B cells express membrane-bound and soluble forms of the CD14 myeloid antigen

The expression of the myeloid differentiation antigen CD14 on the B lineage was analyzed. A CD14-specific monoclonal antibody was used to isolate the antigen from normal B, B-type chronic lymphocytic leukemia cells, and a representative Epstein-Barr virus-transformed B lymphoblastoid cell line (EBVLCL). A soluble form of this protein was detected in the culture supernatant of all the B cell types tested. The molecule expressed in the normal B and B-type chronic lymphocytic leukemia cells was identical in size to the 52,000 mol. wt monocyte-isolated CD14 glycoprotein. A 64,000 mol. wt antigen was isolated from the lymphoblastoid cell line. Similar 2-D gel electrophoretic patterns to that of the monocyte-derived CD14 were obtained from the normal B and B-type chronic lymphocytic leukemia cell-isolated molecules. These similarities were reflected in minor isoelectric point (pI) differences between the polypeptide spots (pI 4.8), in the first dimension, and identical molecular weight (52,000) in the second dimension. The EBVLCL-isolated polypeptide, when analyzed by 2-D gel electrophoresis, showed a pI identical to that of the myeloid antigen (pI 4.6). The isolated soluble form was of smaller (47,000 mol. wt, normal B and B-type chronic lymphocytic leukemia cells) or similar size (64,000 mol. wt, lymphoblastoid cell line) compared with their corresponding membrane-bound forms. Interestingly, two-colour immunofluorescence analysis showed that only two out of four CD14-specific mAb tested bound to the B cells. We conclude that the CD14 antigen is, in fact, expressed in the B lineage. Its cell surface expression and serum level in the prognosis of B-type chronic lymphocytic leukemia patients needs to be evaluated.

Unaltered monocyte function in patients with major depression before and after three months of antidepressive therapy

Monocyte phenotypes and functions were studied in 22 patients with major depression, and compared with those of 22 matched healthy controls. Immune measures were performed before and after dexamethasone suppression, and after 4 and 12 weeks of moclobemide therapy in patients. Seven patients terminated after 4 weeks because of treatment failure; 11 out of 15 patients responded to therapy after 12 weeks. Monocyte human leukocyte antigen class II and CD14 antigen expression, tumor necrosis factor production, and plasma interferon-gamma and neopterin did not differ in patients before treatment and controls. The reaction to dexamethasone was also similar in patients and controls. Neither antidepressive treatment per se nor the clinical response to it affected any immunological parameter. In conclusion, corticosteroid-controlled monocyte functions were similar in untreated and treated depressed patients and in controls, and unrelated to the clinical course of the disease.

Interferon-gamma and interleukin-4 down-regulate soluble CD14 release in human monocytes and macrophages

CD14 is a 53-kd glycoprotein that is mainly expressed in myeloid cells and exists in two forms. The membrane-bound form represents the receptor for complexes of lipopolysaccharide (LPS) with LPS binding protein. The function and regulation of the soluble form are unknown. In the present study we investigated the release of soluble CD14 (sCD14) in cultures of human mononuclear leukocytes, elutriated monocytes, and monocyte-derived macrophages. The release of sCD14 into the medium of the cells cultured for 15 and 45 h was investigated in the absence or presence of selected cytokines. sCD14 release occurred constitutively and correlated with cell number. In monocytes differentiating into macrophages, cumulative release of sCD14 was linear from day 1 to day 7. Spontaneous sCD14 release after 15 h of culture (2 x 10(6) cells/ml) was higher in the supernatant from monocytes (314 +/- 58 ng/ml) than that from mononuclear leukocytes (68 +/- 10 ng/ml) and similar to that from macrophages (469 +/- 79 ng/ml). Cycloheximide and actinomycin D inhibited sCD14 release. Recombinant interferon-gamma (rIFN-gamma) and recombinant interleukin-4 (rIL-4) directly decreased sCD14 release in mononuclear leukocyte, monocyte, and macrophage cultures. rIL-2 and rIFN-alpha reduced sCD14 release into the supernatants of mononuclear leukocytes only. Use of anti-IFN-gamma antibodies indicated that the down-regulation of sCD14 release by rIL-2 and rIFN-alpha was partially due to induction of endogenous IFN-gamma. The down-regulation of sCD14 release by all four cytokines was both time and dose dependent. rIFN-gamma and rIL-4 added simultaneously had a synergistic effect on sCD14 down-regulation. In conclusion, sCD14 release may have an immunomodulatory role in circulating monocytes, is apparently not related to the process of macrophage differentiation, and is selectively down-regulated during an immune response when levels of IFN-gamma and IL-4 are high.

Calcitonin gene-related peptide expression in sepsis: postulation of microbial infection-specific response elements within the calcitonin I gene promoter

BACKGROUND

Recently, we reported an unexpected ubiquitous expression of calcitonin (CT)-mRNA in a hamster peritonitis model of sepsis. Using this animal model,we undertook a study to further investigate the pattern of expression of the calcitonin I (CALC-I) gene and CT gene-related peptide (CGRP)-mRNA in sepsis.

METHODS

Live Escherichia coli impregnated in agar pellets were implanted in the peritoneal cavities of hamsters. Twelve hours after sepsis induction, the septic and healthy control animals were sacrificed and tissues and peritoneal macrophages were collected. CGRP-mRNA content was evaluated by reverse transcription polymerase chain reaction (RT-PCR), quantitated by the Taq-Man technique, and compared with the mRNA expression of CT, tumor necrosis factor alpha (TNF-alpha), and interleukin-6 (IL-6). The 5' untranslated regions of the mRNA and potential alternative splicing sites were identified by 5' rapid amplification of cDNA ends.

RESULTS

We found a tissue-wide, ubiquitous and uniform expression of CGRP-mRNA in all septic tissues examined. CGRP-mRNA was detectable by RT-PCR in various extraneuronal and extrathyroidal septic tissues, but not in healthy control tissues. As found for CT-mRNA in our earlier studies, CGRP-mRNA seemed to be more specifically up-regulated as compared with other classical cytokines (ie, II-6 and TNF-alpha). Importantly, the 5' untranslated sequence in control and septic thyroid was similar to the sequence obtained from septic spleen.

CONCLUSIONS

We postulate the presence of microbial infection-specific response elements in the CALC-I gene promotor, which, upon a specific stimulus, override the tissue-selective expression pattern. This new form of endocrine plasticity may be of importance in the response to systemic inflammation.

Role for CD14, TLR2, and TLR4 in bacterial product-induced anorexia

The cell surface component CD14 and the toll-like receptors 2 and 4 (TLR2 and TLR4) are important in mediating the immune responses to bacterial products in mammals. Using mice genetically deficient in CD14, TLR2, or TLR4, we studied the role of these molecules in the anorectic effects of LPS and muramyl dipeptide (MDP). CD14 or TLR2 knockout (KO) and TLR4-deficient (TLR4-DEF) mice as well as corresponding wild-type (WT) colittermates were injected intraperitoneally at dark onset with LPS (2 microg/mouse), MDP (10 mg/kg), interleukin-1 beta (IL-1 beta, 150 ng/mouse), or vehicle, and food intake was recorded. LPS and MDP reduced food intake in WT mice of all genotypes tested. The anorectic effect of LPS was attenuated (P < 0.04) in CD14-KO and TLR4-DEF mice but not in TLR2-KO (P > 0.05). The anorectic effect of MDP was blunted in CD14-KO and TLR2-KO (P < 0.02) mice but not in TLR4-DEF mice. IL-1 beta reduced food intake similarly in all genotypes tested. These results indicate that CD14 is involved in mediating the anorectic effects of both LPS and MDP. Furthermore, TLR4 and TLR2 are specifically involved in mediating the anorectic effects of LPS and MDP, respectively. The results are consistent with the hypothesis that TLR4 functions as the true LPS receptor and that TLR2 is involved in recognition of gram-positive bacterial products.

Association between the activation of macrophages, changes of iron metabolism and the degree of anaemia in patients with malignant disorders

In this study, we investigated a possible association between the degree of macrophage activation - as measured by serum neopterin concentrations - and disturbances of iron metabolism, determined by the concentrations of ferritin and serum iron, in patients with malignant disorders. Additionally we evaluated correlations between these factors and the degree and type of anaemia. Seventy-three patients, who suffered from non-Hodgkin's lymphoma (NHL) (n = 43), Hodgkin's disease (n = 11), myeloma or monoclonal gammopathy of unknown significance (n = 9), myelodysplastic syndrome (n = 1), and solid tumours (n = 9), were examined. Mean neopterin levels were raised in all groups, patients with NHL showing the highest concentrations. Ferritin but not neopterin concentrations were higher in males than in females. A significant correlation was found between neopterin and ferritin concentrations (p less than 0.01). Considering only female patients the strength of the correlation was the same (p less than 0.02). In addition, we found inverse correlations of neopterin with haemoglobin and iron concentrations (all p less than 0.01). Similar relationships existed in patients during follow-up. Our results support the hypothesis of an association between the degree of activation of macrophages and the development of anaemia by a shift or iron towards the storage sites.

Soluble CD14 activates monocytic cells independently of lipopolysaccharide

The glycoprotein CD14 acts as a receptor for lipopolysaccharide (LPS), either when anchored in the myeloid cell membrane (mCD14) or as a soluble molecule (sCD14) in serum. sCD14-LPS complexes activate cells devoid of mCD14. However, the role of sCD14 independent of LPS is unknown. Therefore, the effect of sCD14 on monocyte functions was investigated in the monocytic cell lines THP1 and Mono Mac 6 and in fresh human monocytes. Under serum-free conditions, endotoxin-free human recombinant sCD14(1-348), (rsCD14(1-348)) induced tumor necrosis factor alpha (TNF-alpha). The TNF-alpha effect was stronger in THP1 cells than in Mono Mac 6 cells or monocytes. It was dose dependent, with a maximum at 1 microg/ml, and time dependent, with a maximum after 2 h. sCD14 purified from urine had the same cytokine-activating capacity. In contrast, C-terminally truncated rsCD14(1-152) was inactive. The rsCD14 effect was not due to LPS contamination, since it was resistant to polymyxin and lipid IVa but sensitive to heat and trypsin. The rsCD14-induced cytokine induction was blocked by preincubation of rsCD14 with a monoclonal anti-CD14 antibody that did not recognize the LPS-binding site. Release of the TNF-alpha disappeared upon pretreatment of rsCD14 in 50% plasma or in complete, heat-inactivated or sCD14-depleted serum. Moreover, cytokine production was no longer observed when rsCD14 was pretreated with thrombocytes. The thrombocyte effect was dose and time dependent. In conclusion, sCD14 is able to activate myeloid cells, and the effect is prevented by the presence of plasma, serum, or thrombocytes.

Elevated adrenaline and increased alpha-adrenoceptor-mediated vasoconstriction in essential hypertension

In patients with essential hypertension, plasma adrenaline, regardless of age, was consistently higher than in normotensive controls; adrenaline correlated with heart rate and the vasodilator response in the forearm circulation produced by postjunctional alpha 1-adrenoceptor blockade with prazosin. This dilator response to prazosin was greater in hypertensive patients. Together, this suggests elevated sympathetic activity and enforced vasoconstriction via postjunctional alpha 1-adrenoceptors in essential hypertension. beta-Adrenoceptor-mediated cardiovascular responses decrease with age and even more with high blood pressure, which contributes to unopposed alpha-adrenoceptor-mediated vasoconstriction. This could explain the transition from an early high cardiac output into a later high peripheral resistance form of hypertension.

Establishment and characterization of long-term cultured cell lines of murine resident macrophages

Murine resident macrophages can proliferate in vitro when they are grown in coculture on a layer of mesothelial or endothelial type feeder cells. Resident macrophages were obtained from lung explants of C57Bl/6 lpr/lpr mice and from spleen explants or peritoneal washing of Balb/c mice; the cells were seeded without further washing. After 3-4 weeks of culture, the macrophages began to proliferate on a confluent layer of feeder cells. The macrophages then could be collected in the fluid phase and reseeded for permanent culture after generation of a new feeder layer. These cells were characterized as macrophages by the following criteria: 1) their morphology, ultrastructure, and adherence properties; 2) more than 90% of the macrophages phagocytized yeasts compared with less than 1% of the feeder cells; 3) the presence of functional Fc and mannose receptors, nonspecific cytoplasmic esterases, and membrane ectoenzymes such as nicotinamide adenine dinucleotide (NAD) glycohydrolase and nucleotide pyrophosphatase; 4) by cytofluorographic phenotype analysis with monoclonal antibodies, characterizing a normal macrophage population (MAC1+, Fcrec+, H-2K+, THY1-, LYT2-, L3T4-). 5) by functional studies proving that the expanded macrophages could function as accessory cells in the induction of lymphocyte proliferation in response to concanavalin A (Con A), that they generated reactive oxygen radicals and that they were cytotoxic for tumor cells. During coculture, growth or activating factors such as macrophage colony-stimulating factor or gamma-interferon were released in the medium. Long-term cultured macrophages had chromosomal abnormalities. Our study suggests that tissue macrophages can proliferate in vitro and hence that it is possible to establish long-term cultured cell lines of macrophages of defined and reproducible characteristics.

Weak effect of metal type and ica genes on staphylococcal infection of titanium and stainless steel implants

Currently, ica is considered to be the major operon responsible for staphylococcal biofilm. The effect of biofilm on susceptibility to staphylococcal infection of different implant materials in vivo is unclear. The interaction of ica-positive (wild-type (WT)) and ica-negative (ica(-)) Staphylococcus aureus and Staphylococcus epidermidis strains with titanium and both smooth and rough stainless steel surfaces was studied by scanning electron microscopy in vitro and in a mouse tissue cage model during 2 weeks following perioperative or postoperative inoculation in vivo. In vitro, WT S. epidermidis adhered equally and more strongly than did WT S. aureus to all materials. Both WT strains, but not ica(-) strains, showed multilayered biofilm. In vivo, 300 CFUs of WT and ica(-)S. aureus led, in all metal cages, to an infection with a high level of planktonic CFUs and only 0.89% adherent CFUs after 8 days. In contrast, 10(6) CFUs of the WT and ica(-) strains were required for postoperative infection with S. epidermidis. In all metal types, planktonic numbers of S. epidermidis dropped to <100 WT, and adherent CFUs were low in WT-infected cages and absent in ica(-)-infected cages after 14 days. Perioperative S. epidermidis inoculation resulted in slower clearance than postoperative inoculation, and in titanium cages adherent WT bacteria survived in higher numbers than ica(-) bacteria. In conclusion, the metal played a minor role in susceptibility to and persistence of staphylococcal infection; the presence of ica genes had a strong effect on biofilm in vitro and a weak effect in vivo; and S. epidermidis was more pathogenic when introduced during implantation than after implantation.

Modulation of interferon-gamma-induced major histocompatibility (MHC) and CD14 antigen changes by lipophilic muramyltripeptide MTP-PE in human monocytes

The lipophilic muramylpeptide derivative muramyltripeptide-phosphatidylethanolamine (MTP-PE, 0.05 to 5 micrograms/ml) and human recombinant interferon-gamma (rIFN-gamma, 1 to 100 U/ml) were applied singly or in combination to fresh human mononuclear blood leucocytes in vitro. After 15 to 72 hr incubation, culture- and drug-induced changes in beta 2-microglobulin (MHC class I associated), HLA-DR (MHC class II), and Leu-M3 (CD14) antigen expression were investigated by flow cytometry; changes in monocyte morphology (forward light scatter and side scatter) were assessed by scatter analysis. It was found that (1) rIFN-gamma caused a simultaneous down-regulation of the CD14 antigen and an up-regulation of MHC class I and class II molecules on the surface of cultured monocytes; (2) MTP-PE, which by itself failed to influence the expression of these antigens, synergized with rIFN-gamma in increasing MHC antigens and reducing CD14; (3) at high concentrations rIFN-gamma reduced monocyte viability to a small but significant extent and this effect was further potentiated by MTP-PE; and (4) untreated monocytes in culture showed an apparently MTP-PE-insensitive increase in size, density, and beta 2-microglobulin, HLA-DR, and CD14 antigen expression. The influence of MTP-PE on rIFN-gamma-induced surface marker changes may contribute to its immunoadjuvant activity in vivo.