Monocyte Chemotactic Responsiveness Research Articles

Anti-Folate Receptor-α IgE but not IgG Recruits Macrophages to Attack Tumors via TNFα/MCP-1 Signaling.

IgE antibodies are key mediators of antiparasitic immune responses, but their potential for cancer treatment via antibody-dependent cell-mediated cytotoxicity (ADCC) has been little studied. Recently, tumor antigen-specific IgEs were reported to restrict cancer cell growth by engaging high-affinity Fc receptors on monocytes and macrophages; however, the underlying therapeutic mechanisms were undefined and in vivo proof of concept was limited. Here, an immunocompetent rat model was designed to recapitulate the human IgE-Fcε receptor system for cancer studies. We also generated rat IgE and IgG mAbs specific for the folate receptor (FRα), which is expressed widely on human ovarian tumors, along with a syngeneic rat tumor model expressing human FRα. Compared with IgG, anti-FRα IgE reduced lung metastases. This effect was associated with increased intratumoral infiltration by TNFα+ and CD80+ macrophages plus elevated TNFα and the macrophage chemoattractant MCP-1 in lung bronchoalveolar lavage fluid. Increased levels of TNFα and MCP-1 correlated with IgE-mediated tumor cytotoxicity by human monocytes and with longer patient survival in clinical specimens of ovarian cancer. Monocytes responded to IgE but not IgG exposure by upregulating TNFα, which in turn induced MCP-1 production by monocytes and tumor cells to promote a monocyte chemotactic response. Conversely, blocking TNFα receptor signaling abrogated induction of MCP-1, implicating it in the antitumor effects of IgE. Overall, these findings show how antitumor IgE reprograms monocytes and macrophages in the tumor microenvironment, encouraging the clinical use of IgE antibody technology to attack cancer beyond the present exclusive reliance on IgG. Cancer Res; 77(5); 1127-41. ©2017 AACR.

Cryopreservation of primary human monocytes does not negatively affect their functionality or their ability to be labelled with radionuclides: basis for molecular imaging and cell therapy.

BackgroundCirculating white blood cells crucially contribute to maintenance and repair of solid organs. Therefore, certain cell populations such as monocytes are attractive targets for use in molecular imaging and cell imaging, e.g. after labelling with radionuclides, as well as for cell therapies. However, the preparation of monocytes may require freezing and thawing to preserve cells for timely and standardised applications. Additional modifications of these cells such as radioisotope labelling are necessary prior to their application in vivo. We therefore tested the hypothesis whether cryopreservation of freshly isolated circulating human monocytes affects their functional phenotype or their suitability for radionuclide labelling.ResultsCD14+CD16− monocytes were isolated from human peripheral blood. They were either directly used for cellular assays and labelling or frozen down using cryoprotectants. In the latter case, cells were thawed prior to further use and analysed for survival, chemotactic responses to various growth factors and adhesion on endothelial cells. In addition, both fresh and cryopreserved monocytes were labelled with radiotracers followed by assessment of survival and chemotactic responses. In all functional assays performed, cryopreserved monocytes did not significantly differ from freshly isolated monocytes with regard to their functionality. Cryopreservation did not affect cell survival. There was no effect on the chemotactic response of monocytes towards different growth factors. Likewise, adhesion properties remained unchanged following cryopreservation. Moreover, the labelling efficiency was similar for freshly isolated and cryopreserved monocytes. Labelling did not negatively affect monocyte survival and function.ConclusionsOur data indicate that cryopreservation of freshly isolated human primary monocytes is feasible and does not negatively affect their functionality when used for labelling and functional assessment.

MONOCYTE CHEMOTACTIC PROTEIN AND RESPONSE TO PEGYLATED INTERFERON-ALPHA-2A TREATMENT IN PATIENTS WITH CHRONIC HEPATITIS C (CHC) GENOTYPE 4.

The prevalence of hepatitis C virus (HCV) infection varies across the world, with the highest number of infections reported in Egypt. Monocyte chemotactic protein-1 (MCP-1) is a potent chemokine, and its hepatic expression is up-regulated during chronic HCV infection. Fifty naive patients with chronic hepatitis C in National Hepatology & Tropical Medicine Research Institute and 20 healthy volunteers as controls were enrolled in a prospective study designed with strict inclusion criteria to nullify the effect of confounding variables and further minimize selection bias. Fifty naive patients were treated with PEG-IFN-a2b, at a dose of 1801 g/kg subcutaneously every week plus ribavirin at a dose of 1000- 1200 mg/day, according to the patient's body weight, for 48 weeks. Quantification of HCV-RNA by real-time PCR and MCP-1 by ELISA were performed for every patient and controls. There was a sta- tistically significant difference between patients and control group as regards the quantity of MCP-1 (P < 0.05) (Mann-Whitney test) (P = 0.004). There was a significant difference between responders and nonresponses regarding MCP-1 (P < 0.05), responders showed a higher percentage of cases with initial MCP-1 < 306 (P < 0.05). We conclude the importance of the detection of MCP-1 expression at the start of therapy as a factor for assessing the likelihood of HCV genotype 4 patients to achieving a sustained virological response to treatment with IFN-a2 in combination with ribavirin.

The role of the ribosomal protein S19 C-terminus in altering the chemotaxis of leucocytes by causing functional differences in the C5a receptor response

Ribosomal protein S19 (RP S19) oligomers have been discovered as the first chemoattractant of migrating monocytes/macrophages to apoptotic cells via the C5a receptor (C5aR). In contrast to C5a, a fusion of the C-terminus (I(134)-H(145)) of RP S19 to C5a, the C5a/RP S19 chimera, substitutes for the RP S19 oligomers and is able to replicate C5aR antagonist-induced and agonist-induced dual effects on neutrophil and monocyte chemotactic responses, respectively. We recently discovered a gain of binding affinity when the I(134)-H(145) inhibited the activation of neutrophil C5aR-mediated chemotactic pathways. However, the opposing ligand-dependent chemotactic mechanisms are not fully understood. In this study, a loss of this additional binding affinity appeared to cause the monocyte C5aR to activate an alternative signalling pathway. The p38 mitogen activated-protein kinase (MAPK) pathway was linked to cell migration rather than a classical extracellular-regulated kinase 1/2 pathway commonly used by C5a. C5aR internalization was not involved in the alternative chemotactic pathway. We propose a model of activation involving a C5aR co-molecule that interferes with the C5aR-Gi protein interaction upon binding to the I(134)-H(145) in neutrophils; however, a free I(134)-H(145) from the C5aR co-molecule can guide the alternative activation of the chemotactic p38MAPK pathway in monocytes/macrophages.

Maggot secretions suppress pro-inflammatory responses of human monocytes through elevation of cyclic AMP

Aims/hypothesisMaggots of the blowfly Lucilia sericata are used for the treatment of chronic wounds. As monocytes may contribute to the excessive inflammatory responses in such wounds, this study focussed on the effects of maggot secretions on the pro-inflammatory activities of these cells.MethodsFreshly isolated monocytes were incubated with a range of secretions for 1 h and then stimulated with lipopolysaccharides (range 0–100 ng/ml) or lipoteichoic acid (range 0–5 µg/ml) for 18 h. The expression of cell surface molecules, cytokine and chemokine levels in culture supernatants, cell viability, chemotaxis, and phagocytosis and killing of Staphylococcus aureus were measured.ResultsMaggot secretions dose-dependently inhibited production of the pro-inflammatory cytokines TNF-α, IL-12p40 and macrophage migration inhibitory factor by lipopolysaccharides- and lipoteichoic acid-stimulated monocytes, while enhancing production of the anti-inflammatory cytokine IL-10. Expression of cell surface receptors involved in pathogen recognition remained unaffected by secretions. In addition, maggot secretions altered the chemokine profile of monocytes by downregulating macrophage inflammatory protein-1β and upregulating monocyte chemoattractant protein-1 and IL-8. Nevertheless, chemotactic responses of monocytes were inhibited by secretions. Furthermore, maggot secretions did not affect phagocytosis and intracellular killing of S. aureus by human monocytes. Finally, secretions induced a transient rise in the intracellular cyclic AMP concentration in monocytes and Rp-cyclic AMPS inhibited the effects of secretions.Conclusions/interpretationMaggot secretions inhibit the pro-inflammatory responses of human monocytes through a cyclic AMP-dependent mechanism. Regulation of the inflammatory processes by maggots contributes to their beneficial effects on chronic wounds.

Nerve growth factor stimulation promotes CXCL-12 attraction of monocytes but decreases human immunodeficiency virus replication in attracted population

The neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) are key molecules in the central nervous system development, which also exert specific effects on cells of the immune system. With regard to the latter, in vitro as well as in vivo data suggested that neurotrophins may play a role in human immunodeficiency virus (HIV) infection, especially in perivascular spaces where infiltrated macrophages express NGF. In the present study, we examined the expression of neurotrophins and their receptors in human monocyte-derived macrophages (MDMs) during infection by the R5 prototype HIV1/Ba-L strain. We then assessed to what extent neurotrophins themselves modulate infected macrophage survival and the level of virus production. The data show that neurotrophins and neurotrophin receptors are not modulated during HIV replication. Likewise, exogenous neurotrophins, or alternatively the blocking of neurotrophin receptors, neither modulated MDM sensitivity to HIV infection and replication nor altered their viability. In contrast, NGF clearly increased CD184 expression in macrophages, but this did not sensitize them to the X4 isolate HIV-1/Lai infection. Nevertheless, NGF enhanced monocyte chemotactic response to low CXCL-12 concentration regardless of infection. Surprisingly, CXCL-12-attracted monocytes from NGF-stimulated, HIV-infected cultures produced decreased amounts of virus progeny than their non-NGF-stimulated counterparts. This suggests a preferential effect on uninfected monocytes. Together these findings suggest a role for NGF in the continuous attraction of activated monocytes to the perivascular spaces, contributing to the chronic inflammatory state rather than neuroinvasion by HIV.

Evaluating the potential of IP-10 and MCP-2 as biomarkers for the diagnosis of tuberculosis

The aim of the present study was to evaluate the potential of diagnostic tests based on interferon-gamma inducible protein (IP)-10 and monocyte chemotactic protein (MCP)-2, and compare the performance with the QuantiFERON TB Gold In-Tube (QFT-IT; Cellestis, Carnagie, Australia) test. IP-10 and MCP-2 were determined in supernatants from whole blood stimulated with Mycobacterium tuberculosis-specific antigens. Samples were obtained from 80 patients with culture- and/or PCR-proven tuberculosis (TB), and 124 unexposed healthy controls: 86 high school students and 38 high school staff. IP-10 and MCP-2 test cut-offs were established based on receiver operating characteristic curve analysis. TB patients produced significantly higher levels (median) of IP-10 (2158 pg x mL(-1)) and MCP-2 (379 pg x mL(-1)) compared with interferon (IFN)-gamma (215 pg x mL(-1)). The QFT-IT, IP-10 and MCP-2 tests detected 81, 83 and 71% of the TB patients; 0, 3 and 0% of the high school students and 0, 16 and 3% of the staff, respectively. Agreement between tests was high (>89%). By combining IP-10 and IFN-gamma tests, the detection rate increased among TB patients to 90% without a significant increase in positive responders among the students. In conclusion, interferon-gamma inducible protein-10 and monocyte chemotactic protein-2 responses to Mycobacterium tuberculosis-specific antigens could be used to diagnose infection. Combining interferon-gamma inducible protein-10 and interferon-gamma may be a simple approach to increase the detection rate of the Mycobacterium tuberculosis-specific in vitro tests.

Hypercholesterolaemia impairs monocyte function in CAD patients

Hypercholesterolaemia (HC) impairs arteriogenesis, i.e. collateral artery growth. Monocytes are crucial mediators of arteriogenesis. We investigated the impact of the cardiovascular risk factor HC on ligand-induced monocyte chemotaxis. The migratory response of monocytes towards the arteriogenic ligands vascular endothelial growth factor-A (VEGF-A) and monocyte chemoattractant protein-1 (MCP-1) in hypercholesterolaemic coronary artery disease (CAD) patients (n = 14), hypercholesterolaemic controls (n = 8) and age-matched healthy controls (n = 19) was analysed. Furthermore, the serum VEGF-A level was determined in all individuals. VEGF-A-induced monocyte chemotaxis was severely impaired in hypercholesterolaemic CAD patients when compared with age-matched healthy controls (P < 0.001). The same was true for the migratory response towards MCP-1 (P < 0.001). VEGF-A- and MCP-1-induced monocyte chemotaxis of hypercholesterolaemic controls was also decreased in comparison with the healthy control group, but not as severe as observed in the hypercholesterolaemic CAD patients. VEGF-A serum levels did not differ between the three study groups. Hypercholesterolaemia severely impairs monocyte function in hypercholesterolaemic CAD patients. Monocyte dysfunction is probably connected to impaired collateral artery growth. The duration of the cardiovascular risk factor HC seems to influence the extent of monocyte dysfunction, as there exists a continuum of diminished monocyte chemotaxis in the three study groups. Further trials are warranted in order to determine whether statins can reverse the negative influence of HC on cell function.

Feeling No (Chronic) Pain

Abbadie et al. investigated the role of chemotactic chemokine receptor 2 (CCR2) in pain and discovered evidence implicating this receptor in chronic neuropathic pain. Chronic neuropathic pain, a condition that can have substantial effects on quality of life and may interfere with common activities of daily living, can be difficult to treat and remains poorly understood. Abbadie et al. compared the responses of wild-type mice and mutant mice lacking CCR2, which mediates the chemotactic response of monocytes to the inflammatory chemokine monocyte attractant protein-1 (MCP-1), in several models of pain. After injury to the sciatic nerve, the mutant mice lacked a behavioral response associated with chronic neuropathic pain. In wild-type mice, nerve injury led to increased levels of CCR2 in the sciatic nerve and dorsal root ganglia. In addition, numerous CCR2-immunoreactive macrophages were identified in the sciatic nerve and CCR2-immunoreactive microglia were observed in the spinal cord. The CCR2 knockout mice had fewer astrocytes in the dorsal horn of the spinal cord after nerve injury than did wild-type mice, and their microglia showed lower levels of p38 mitogen-activated protein kinase. Both of these observations are indicative of reduced glial activation. CCR2's role in chronic neuropathic pain could lead to new therapies for this condition. C. Abbadie, J. A. Lindia, A. M. Cumiskey, L. B. Peterson, J. S. Mudgett, E. K. Bayne, J. A. DeMartino, D. E. MacIntyre, M. J. Forrest, Impaired neuropathic pain responses in mice lacking the chemokine receptor CCR2. Proc. Natl. Acad. Sci. U.S.A. 100 , 7947-7952 (2003). [Abstract] [Full Text]

Effects of Shuanghuanglian and Qingkailing, two multi-components of traditional Chinese medicinal preparations, on human leukocyte function

Qingkailing (QKL) and Shuanghuanglian (SHHL) are two commonly used Chinese herbal preparations with reported antiinflammatory activity. The effects of these two preparations on the capacity of staphylococcal toxic shock syndrome toxin 1 (TSST-1) to stimulate the production of cytokines (IL-1β, IL-6, TNF-α, IFN-γ) and chemokines (MIP-1α, MIP-1β and MCP-1) by peripheral blood mononuclear cell (PBMC) was tested. We also evaluated their effect on LPS-stimulated NF-κB transcriptional activity in a THP-1 cell line, and on human monocyte chemotactic response to chemoattractants. Non-cytotoxic concentrations of QKL (0.1~2%) and SHHL (6~120 μg) significantly inhibited production of cytokines and chemokines in a dose-dependent manner (P < 0.05). Both, QKL at 1:100 and SHHL at 60 μg/ml, markedly inhibited RANTES, MIP-1α, SDF-1α and fMLP induced human monocyte migration (P < 0.05 or 0.01). QKL (1%) did not inhibit monocyte chemotaxis induced by super-or sub-optimal concentrations of fMLP (10 -5, 10 -6 and 10 -10 M), but only inhibited chemotaxis induced by optimal concentrations of fMLP at 10 -7, 10 -8 and 10 -9 M. QKL (0.1% or 1%) and SHHL(6 or 60 μg/ml) markedly inhibited LPS-induced NF-κB activity in THP-1 cells. The results suggested that the pharmacological basis for the antiinflammatory effects of QKL and SHHL is the result of suppression of NF-κB regulated gene transcription, leading to suppressed production of proinflammatory cytokine and chemokine. Interference with leukocyte chemotaxis also contributes to the antiinflammatory and immunomodulating effects of these medicinals. Identification of the responsible components in these two herbal preparations may yield compounds suitable for structural modification into potent novel drugs.

Delineating Integrin Activation and Migration

Monocyte chemoattractant protein-1 (MCP-1) is important for both integrin activation and cell migration during the chemotactic response of monocytes. Although these two processes are closely connected, the signaling pathways associated with each have not been well defined. Ashida et al. show that different mitogen-activated protein kinase (MAPK) pathways are required in each process. Inhibition of p38 MAPK inhibited chemotaxis, whereas ERK (extracellular-regulated kinase) inhibition greatly reduced integrin activation, as measured by adhesion to fibronectin. Additionally, inhibiting the function of Rho or Rho kinase also blocked migration but not integrin activation. Although the biochemical signaling point at which both MCP-1-dependent pathways diverge has not been identified, the elucidation of specific proteins involved in migration and integrin activation should help clarify these signaling pathways. N. Ashida, H. Arai, M. Yamasaki, T. Kita, Distinct signaling pathways for MCP-1-dependent integrin activation and chemotaxis. J. Biol. Chem. 276 , 16555-16560 (2001). [Abstract] [Full Text]

Distinct chemotactic and angiogenic activities of peptides derived from Kaposi's sarcoma virus encoded chemokines.

The vMIPs are chemokine-like proteins expressed by the Kaposi's sarcoma-associated herpesvirus (KSHV/HHV8) during the lytic phase of viral infection. vMIP-I activates CCR8, a chemokine receptor expressed by Th2 lymphocytes and cultured monocytes. vMIP-II is an agonist for CCR3, a receptor expressed by eosinophils, and an antagonist for several other chemokine receptors. Both are highly angiogenic in the chick chorio-allantoic membrane. We designed and tested three 26-mer peptides, derived from vMIP-I (pK-I), from vMIP-II (pK-II) and from the control MIP-1alpha (pM), spanning key residues of chemokines. pK-I, pK-II and pM all were able to activate a strong chemotactic response in monocytes, higher than parental vMIP-I and II. This corresponded to induction of calcium fluxes in these cells, typical of chemokines. Interestingly, pK-II and pM were also active on PMN neutrophils. In vivo studies (matrigel sponge and rabbit cornea models) showed that pK-I retains the strong angiogenic potential exerted by vMIP-I, while pK-II and pM induced an inflammatory response, probably mediated by PMN recruitment. Our observations indicate that chemokine-derived peptides can show biological activity at pharmacological concentrations. pK-I, in particular, displays the angiogenic activity of full-length vMIP-I, while all peptides appear to have acquired additional properties, stimulating new cellular targets.

Inhibition of MIP-1α-induced human neutrophil and monocyte chemotactic activity by reactive oxygen and nitrogen metabolites

Peroxynitrite, formed by the reaction between nitric oxide (NO) and superoxide, has been implicated in the pathogenesis of numerous disease processes. Several studies have shown that peroxynitrite-induced protein nitration may compromise enzyme and protein function. We hypothesized that peroxynitrite may regulate cytokine function during inflammation. To test this hypothesis, the neutrophil and monocyte chemotactic responses of macrophage inflammatory protein-1α (MIP-1α) incubated with and without peroxynitrite were evaluated. Peroxynitrite attenuated neutrophil chemotactic activity (NCA) and monocyte chemotactic activity (MCA) by MIP-1α in a dose-dependent manner (P <.05). The inhibitory effects were not significant on NCA and MCA induced by leukotriene B4 or complement-activated serum incubated with peroxynitrite. The reducing agents deferoxamine, dithiothreitol, and exogenous L -tyrosine abrogated the NCA and MCA inhibition by peroxynitrite. Papa-NONOate, an NO donor, or a combination of xanthine and xanthine oxidase to generate superoxide, did not show an inhibitory effect on NCA and MCA induced by MIP-1α. In contrast, 3-morpholinosydnonimine (SIN-1), a peroxynitrite generator, elicited a concentration-dependent reduction in NCA and MCA induced by MIP-1α. Consistent with its capacity to reduce NCA and MCA, peroxynitrite treatment reduced MIP-1α binding to neutrophils and monocytes. Nitrotyrosine was detected in the MIP-1α incubated with peroxynitrite. These findings are consistent with nitration of tyrosine by peroxynitrite with subsequent inhibition of MIP-1α binding to neutrophils and monocytes and a reduction in NCA and MCA. These data demonstrate that peroxynitrite modulates the inflammatory cell migration by MIP-1α, and they suggest that oxidants may play an important role in the regulation of MIP-1α-induced inflammatory cell chemotaxis. (J Lab Clin Med 2000;135:161-9)

Bidirectional heterologous desensitization of opioid and chemokine receptors.

Opioids are known to suppress a number of elements of the immune response, including antimicrobial resistance, antibody production, and delayed-type hypersensitivity. Phagocytic cells may be particularly susceptible to opioid administration, since reduced production of the cytokines IL-1, IL-6 and TNF-alpha, monocyte-mediated phagocytosis, and both neutrophil and monocyte chemotaxis have all been well established. Earlier studies have shown that both mu- and delta-opioid agonists induce a chemotactic response in monocytes and neutrophils. In addition, mu- and delta-opioid administration inhibited the chemotactic response of these cell populations to a number of chemokines through a process of heterologous desensitization. We report here that mu-, delta-, and kappa-opioid agonists also induce a chemotactic response in T lymphocytes. Using the human T-cell line Jurkat, we have confirmed previous observations that pre-incubation with met-enkephalin (MetEnk), an endogenous opioid agonist, prevents the subsequent chemotactic response to the chemokine RANTES. On the other hand, treatment with MetEnk does not alter the response to the chemokine SDF-1 alpha. Moreover, we found that pre-treatment with RANTES prevented a subsequent response of monocytes to the mu-opioid agonist DAMGO. These results suggest that activation of members of the opioid and chemokine receptor families leads to downregulation of each other's leukocyte migratory activities.

Chemokine receptor CCR2 expression and monocyte chemoattractant protein-1-mediated chemotaxis in human monocytes. A regulatory role for plasma LDL.

The subendothelial accumulation of macrophage-derived foam cells is one of the hallmarks of atherosclerosis. The recruitment of monocytes to the intima requires the interaction of locally produced chemokines with specific cell surface receptors, including the receptor (CCR2) for monocyte chemoattractant protein-1 (MCP-1). We have previously reported that monocyte CCR2 gene expression and function are effectively downregulated by proinflammatory cytokines. In this study we identified low density lipoprotein (LDL) as a positive regulator of CCR2 expression. Monocyte CCR2 expression was dramatically increased in hypercholesterolemic patients compared with normocholesterolemic controls. Similarly, incubation of human THP-1 monocytes with LDL induced a rapid increase in CCR2 mRNA and protein. By 24 hours the number of cell surface receptors was doubled, causing a 3-fold increase in the chemotactic response to MCP-1. The increase in CCR2 expression and chemotaxis was promoted by native LDL but not by oxidized LDL. Oxidized LDL rapidly downregulated CCR2 expression, whereas reductively methylated LDL, which does not bind to the LDL receptor, had only modest effects on CCR2 expression. A neutralizing anti-LDL receptor antibody prevented the effect of LDL, suggesting that binding and internalization of LDL were essential for CCR2 upregulation. The induction of CCR2 expression appeared to be mediated by LDL-derived cholesterol, because cells treated with free cholesterol also showed increased CCR2 expression. These data suggest that elevated plasma LDL levels in conditions such as hypercholesterolemia enhance monocyte CCR2 expression and chemotactic response and potentially contribute to increased monocyte recruitment to the vessel wall in chronic inflammation and atherogenesis.

Influence of Chlorpyrifos, an Organophosphate Insecticide, on the Immune System of Nile Tilapia

Abstract Recent reports about laboratory rodents indicate that parameters of the immune system, including total immune cell number in hematopoietic compartments and ability to elicit both specific and nonspecific immune responses, may be among the most sensitive indicators of environmental contaminant exposure. In several species of wild-caught and laboratory-exposed fish, altered monocyte chemotactic ability, chemiluminescent responses (metabolic oxidative burst), and phagocytosis have recently been found to be associated with exposure to polycyclic aromatic hydrocarbons and organometals, indicating that parameters of immunity may also served as potential sensitive markers of chemical exposure in fish. In the present experiments, Nile tilapia Oreochromis niloticus exposed to the organophosphate insecticide, chlorpyrifos, at a concentration of 1 μg/L displayed significantly lower total pronephros cell counts than did untreated controls. In addition, macrophages isolated from the pronephros of the treated ...

Activation of thromboxane A2 receptors alters lipopolysaccharide-induced adherence of THP-1 cells.

U46619, a thromboxane A2 (TXA2) mimetic, inhibits human monocyte chemotactic responses, suggesting that TXA2, an arachidonic acid metabolite, may alter monocyte adhesion. We tested the hypothesis that TXA2 alters Lipopolysaccharide (LPS)-induced adhesion of THP-1 cells, a human monocytic leukemia cell line. Salmonella enteritidis endotoxin (1 microgram/mL) induced a significant (p < .05; n = 6) increase in the adherence of THP-1 cells (basal, 5.7 +/- 1.8 micrograms/well; LPS, 78.8 +/- 4.9 micrograms/well). Treatment of THP-1 cells with indomethacin or TXA2 receptor antagonists before LPS stimulation significantly (p < .05) enhanced adhesion, suggesting that endogenously produced TXA2 or prostaglandins alter LPS-induced THP-1 cell adhesion. TXA2 mimetics significantly decreased (p < .05; n = 5 and n = 3, respectively) LPS-induced THP-1 cell adhesion. This effect was blocked by three structurally dissimilar TXA2 receptor antagonists. These results support the hypothesis that TXA2 alters LPS-induced adhesion of THP-1 cells.

Interleukin-8 and monocyte chemotactic activating factor responses to cardiopulmonary bypass

Cardiac operations with cardiopulmonary bypass cause a systemic inflammatory response. Neutrophils and monocytes-macrophages play an important role in triggering the initiation of the inflammatory response. Recently, some kinds of cytokines that are powerful leukocyte chemotactic factors have been characterized concerning an inflammatory response: interleukin-8 has a potent chemoattractant activity for neutrophils, and monocyte chemoattractant factor has monocyte-macrophage chemotactic activity. To investigate the possible roles of the cytokines in the inflammatory response in cardiopulmonary bypass, 12 adult patients undergoing cardiopulmonary bypass were studied for measurement of interleukin-8 and monocyte chemoattractant factor. Systemic blood was collected before cardiopulmonary bypass, at the end of cardiopulmonary bypass, and at 3, 12, 24, and 48 hours after cardiopulmonary bypass from the patients' radial arteries. Significant increases in levels of interleukin-8 and monocyte chemoattractant factor were detected with a peak level at 3 hours after bypass compared with levels before cardiopulmonary bypass (p < 0.05). This study demonstrated that interleukin-8 and monocyte chemoattractant factor are released into the circulation after adult hypothermic cardiopulmonary bypass and reach a maximum level 3 hours after bypass.

C5a-induced migration of human monocytes is primed by dexamethasone.

Allergic inflammation in the lung is characteristic of allergic asthma. This inflammatory process is inhibited by treatment with glucocorticoids. One of the cell types involved in the inflammatory process, the monocyte, is found in enhanced numbers in mucosal lung biopsies of asthmatic patients. Little is known about the mechanisms that lead to increased numbers of monocytes in lung tissue. We studied one of the processes involved, chemotaxis, in a modified Boyden Chamber assay. The effect of the antiinflammatory drug dexamethasone was tested on monocyte chemotactic responses to complement fragment C5a. Human monocytes from peripheral blood of normal human volunteers were purified by centrifugal elutriation. The monocytes showed a reproducible chemotactic response toward C5a with an optimum at a concentration of 10(-9) M. After culture of the monocytes overnight, the monocyte responses were clearly impaired. It is interesting that upon culture, dexamethasone increased monocyte chemotaxis in a dose-dependent manner. Analysis of the filters with an image analyzer showed that the effect was not through modulation of a subpopulation of monocytes. This steroid effect was specific and modulated via steroid receptors, because the introduction of RU 38486, a steroid receptor antagonist, completely inhibited the effect of dexamethasone. These findings are a further illustration of the complex mechanisms involved in the orchestration of the inflammatory response in asthma.

Comparison of retroviral p15E-related factors and interferon alpha in head and neck cancer.

Head and neck squamous cell carcinomas (HNscc) produce low-molecular-mass factors (low-M(r) factors, M(r) < or = 25,000), which are antigenically related to the immunosuppressive retroviral transmembrane envelope protein p15E. These P15E-related tumour factors are thought to be responsible for some immunological impairments found in these patients (particularly the defective monocyte chemotaxis). A sequential and functional homology has been reported to exist between a bioactive fragment of interferon alpha (IFN alpha) and the putative immunosuppressive region of retroviral p15E (CKS-17). In this study we investigated (a) a possible functional and structural relationship between p15E and IFN alpha, and (b) the presence of and the relationship between p15E-related low-M(r) factors and IFN alpha in HNscc patients. We report the following results. (a) Recombinant human (rhu) IFN alpha was able to inhibit monocyte chemotaxis. (b) The anti-p15E antibodies crossreacted with rhuIFN alpha in a dot-blot technique; however, the anti-IFN alpha antibodies did not crossreact with disrupted murine leukaemia virus (p15E source). (c) Low-M(r) factors (n = 8-11) prepared from the sera of HNscc patients, which inhibit the monocyte chemotactic responsiveness, could be adsorbed by the anti-p15E antibodies as well as by the anti-IFN alpha antibodies. However, the abilities of the factors to adsorb to the two categories of antibodies (namely, anti-p15E and anti-IFN alpha) did not correlate. (d) Immunohistochemically we found IFN alpha-related epitopes, in almost all HNscc specimens studied (17/18), in locations distinctive from those of p15E-related factors. The anti-IFN alpha antibodies used in this study mainly reacted with basal epithelial cells close to the basal membrane, the prickle and granular cells of the squamous cell carcinomas. The anti-p15E antibodies mainly reacted with corneal layers, the granular and prickle cells, and did not react with basal epithelial cells. Our findings suggest that the immunosuppressive factors produced by HNscc cells are heterogeneous and p15E- and/or IFN alpha-related.