Process Of Macrophage Activation Research Articles

#5536 CIRCULATING LEVELS OF COPEPTIN, GROWTH DIFFERENTIATION FACTOR 15 (GDF15) AND INTERLEUKIN 6 (ILA-6) IN PATIENTS WITH ADVANCED KIDNEY DISEASE

Abstract Background and Aims The search for new serum biomarkers of cardiovascular risk and mortality in patients with CKD is relevant to improve the monitoring of these patients. Copeptin is a glycopeptide that is released equimolarly with arginine-vasopressin. GDF-15 is a cytokine involved in macrophage activation processes and is a marker of response to oxidative stress, and IL-6 as a marker of systemic inflammation. Objective: To study the serum levels of copeptin, GDF-15 and IL-6 in patients with advanced CKD. Method Cross-sectional study in 32 patients with advanced CKD. In all patients, the estimated glomerular filtration rate (eGFR) was determined by CKD-EPI, the albumin/creatinine ratio (CrAI) and the serum concentrations of copeptin (immunofluorescence, Thermo Fisher), GDF-15 (chemiluminescence, Roche Diagnostics International) and IL-6 (Siemens Healthineers). Results were compared to laboratory reference values (RVs) for copeptin (VN<4.2 pmol/L) and IL-6 (VN<4.4 pg/mL). The VR of GDF-15 (708±227 pg/ml) corresponds to own data from 10 Blood Bank donors. Results for copeptin and GDF-15 (normal distribution) are shown as mean ± SD. IL-6 results (without normal distribution) as median and interquartile range. Results In CKD we observed an increase in copeptin (26.9±22 pmol/l, 90% >4.2 VR) and GDF-15 (4703±2683 pg/ml p<0.0001 vs. control population). Median IL6 3.2 pg/ml (IQR: 2.7-5.1, 35% >4.4 VR). We did not find differences in the levels of copeptin, GDF-15 or IL-6 based on age, sex and presence or absence of diabetes. A significant correlation was found between GDF15 levels and eGFR (r=-0.54 p<0.002). Conclusion Serum levels of copeptin and GDF-15, but not IL6, are increased in CKD patients. Our data suggest a significant inverse relationship between GDF15 and eGFR. More studies are needed to know the possible role of GDF-15 on the progression of kidney damage and cardiovascular complications in patients with CKD.

Sequential activation of M1\xa0and M2 phenotypes in macrophages by Mg degradation from Ti-Mg alloy for enhanced osteogenesis

BackgroundEven though the modulatory effects of Magnisum (Mg) and its alloys on bone-healing cells have been widely investigated during the last two decades, relatively limited attention has been paid on their inflammation-modulatory properties. Understanding the activation process of macrophages in response to the dynamic degradation process of Mg as well as the relationship between macrophage phenotypes and their osteogenic potential is critical for the design and development of advanced Mg-based or Mg-incorporated biomaterials.MethodsIn this work, a Ti-0.625 Mg (wt.%) alloy fabricated by mechanical alloying (MA) and subsequent spark plasma sintering (SPS) was employed as a material model to explore the inflammatory response and osteogenic performance in vitro and in vivo by taking pure Ti as the control. The data analysis was performed following Student’s t-test.ResultsThe results revealed that the macrophages grown on the Ti-0.625 Mg alloy underwent sequential activation of M1 and M2 phenotypes during a culture period of 5 days. The initially increased environmental pH (~ 8.03) was responsible for the activation of M1 macrophages, while accumulated Mg2+ within cells contributed to the lateral M2 phenotype activation. Both M1 and M2 macrophages promoted osteoblast-like SaOS-2 cell maturation. In vivo experiment further showed the better anti-inflammatory response, regenerative potentiality and thinner fibrous tissue layer for the Ti-0.625 Mg alloy than pure Ti.ConclusionThe results highlighted the roles of Mg degradation in the Ti-0.625 Mg alloy on the sequential activation of macrophage phenotypes and the importance of modulating M1-to-M2 transition in macrophage phenotypes for the design and development of inflammation-modulatory biomaterials.

Target-Dependent Coordinated Biogenesis of Secondary MicroRNAs by miR-146a Balances Macrophage Activation Processes.

ABSTRACTMicroRNAs (miRNAs) repress protein expression by binding to the target mRNAs. Exploring whether the expression of one miRNA can regulate the abundance and activity of other miRNAs, we noted the coordinated biogenesis of miRNAs in activated macrophages. miRNAs with higher numbers of binding sites (the “primary” miRNAs) induce expression of other miRNAs (“secondary” miRNAs) having binding sites on the 3′ untranslated region (UTR) of common target mRNAs. miR-146a-5p, in activated macrophages, acts as a “primary” miRNA that coordinates biogenesis of “secondary” miR-125b, miR-21, or miR-142-3p to target new sets of mRNAs to balance the immune responses. During coordinated biogenesis, primary miRNA drives the biogenesis of secondary miRNA in a target mRNA- and Dicer1 activity-dependent manner. The coordinated biogenesis of miRNAs was observed across different cell types. The target-dependent coordinated miRNA biogenesis also ensures a cumulative mode of action of primary and secondary miRNAs on the secondary target mRNAs. Interestingly, using the “primary” miR-146a-5p-specific inhibitor, we could inhibit the target-dependent biogenesis of secondary miRNAs that can stop the miRNA-mediated buffering of cytokine expression and inflammatory response occurring in activated macrophages. Computational analysis suggests the prevalence of coordinated biogenesis of miRNAs also in other contexts in human and in mouse.

MicroRNA exporter HuR clears the internalized pathogens by promoting pro‐inflammatory response in infected macrophages

HuR is a miRNA derepressor protein that can act as miRNA sponge for specific miRNAs to negate their action on target mRNAs. Here we have identified how HuR, by inducing extracellular vesicles‐mediated export of miRNAs, ensures robust derepression of miRNA‐repressed cytokines essential for strong pro‐inflammatory response in activated mammalian macrophages. Leishmania donovani, the causative agent of visceral leishmaniasis, on the contrary alters immune response of the host macrophage by a variety of complex mechanisms to promote anti‐inflammatory response essential for the survival of the parasite. We have found that during Leishmania infection, the pathogen targets HuR to promote onset of anti‐inflammatory response in mammalian macrophages. In infected macrophages, Leishmania also upregulate protein phosphatase 2A that acts on Ago2 protein to keep it in dephosphorylated and miRNA‐associated form. This causes robust repression of the miRNA‐targeted pro‐inflammatory cytokines to establish an anti‐inflammatory response in infected macrophages. HuR has an inhibitory effect on protein phosphatase 2A expression, and mathematical modelling of macrophage activation process supports antagonistic miRNA‐modulatory roles of HuR and protein phosphatase 2A which mutually balances immune response in macrophage by targeting miRNA function. Supporting this model, ectopic expression of the protein HuR and simultaneous inhibition of protein phosphatase 2A induce strong pro‐inflammatory response in the host macrophage to prevent the virulent antimonial drug‐sensitive or drug‐resistant form of L. donovani infection. Thus, HuR can act as a balancing factor of immune responses to curtail the macrophage infection process by the protozoan parasite.

The Macrophage Activation Induced by Bacillus thuringiensis Cry1Ac Protoxin Involves ERK1/2 and p38 Pathways and the Interaction with Cell-Surface-HSP70.

Here, we aimed to further characterize the mechanisms involved in protoxin (p) Cry1Ac-induced macrophage activation. We demonstrated that pCry1Ac induces MAPK ERK1/2, p38, and JNK phosphorylation in RAW264.7 macrophages. Because MAPK activation is mainly triggered via ligand-receptor interactions, we focused on the identification of potential pCry1Ac-receptor proteins. Flow cytometry and confocal analysis showed specific saturable pCry1Ac-binding to the macrophage surface and evidenced its internalization via the clathrin-pathway. We performed immunoprecipitation assays and identified by MALDI-TOF-TOF several possible pCry1Ac-binding proteins, such as heat shock proteins (HSPs), vimentin, α-enolase, and actin; whose interaction and presence was confirmed, respectively, by ligand blot and Western blot assays. We also detected cell-surface (cs) pCry1Ac-HSP70 colocalization, so HSP70 was chosen for further characterization. Co-immunoprecipitation with HSP70 antibodies followed by Western blot confirmed the pCry1Ac-HSP70 interaction. Furthermore, pretreatment of RAW264.7 cells with HSP70 antibodies reduced pCry1Ac-induced ERK1 phosphorylation and MCP-1 production; thus suggest the functional participation of csHSP70 in pCry1Ac-induced macrophage activation. csHSP70 also was evaluated in peritoneal-cavity (PerC) macrophages of untreated BALB/c mice, interestingly it was found that the predominant population namely large-peritoneal-macrophages (LPM) displayed csHSP70 + hi. Furthermore, the dynamics of PerC macrophage subsets, LPM, and small-peritoneal macrophages (SPM) were evaluated in response to in vivo pCry1Ac stimuli in presence or not of phenylethynesulfonamide (PES) a functional HSP70 inhibitor. It was found that pCry1Ac increased the proportion of SPM CD11b + F4/80 + lowMHCII + csHSP70 + low and markedly reduced the amount of LPM CD11b + F4/80 + hiMHCII-csHSP70 + hi; while PES, partially suppressed this pCry1Ac-induced effect, further suggesting the participation of HSP70 in macrophage activation process. J. Cell. Biochem. 119: 580-598, 2018. © 2017 Wiley Periodicals, Inc.

Low-grade elevation of fibrinogen-degradation products is an important parameter to identify acute presentation of autoimmune hepatitis

ABSTRACTObjective: Diagnosing early-stage acute autoimmune hepatitis (AIH) without pathological findings is difficult. Recent reports indicated that macrophages are not activated during disease development, unlike in other acute liver injuries. We suggest that hepatitis without macrophage activation should lack sinusoidal fibrin deposition, which might help diagnose the acute presentation of AIH. Material and methods: To test this hypothesis, 295 consecutive patients with acute liver injury enrolled into this study. Their clinical data on admission were analyzed to verify the differences between acute presentation of AIH and other liver injuries. Results: The distribution of plasma fibrinogen degradation products (FDP) showed two clusters: patients without elevated FDP and those with measurable FDP levels of various degrees. Most AIH patients are included in the former. Multivariate logistic analysis of patients’ laboratory data was performed for useful parameters to identify the acute presentation of AIH. FDP, alanine transaminase, zinc sulfate turbidity test and HBsAg levels were significant. Based on the odds ratio obtained from the analysis, we assigned each result individual points and constructed a convenient scoring system, which showed high sensitivity and specificity to identify AIH. Additionally, the area under the receiver operating characteristic curve was 0.928. Conclusions: Our results indicated that the process of macrophage activation and subsequent sinusoidal fibrin deposition was not involved in the development of the acute presentation of AIH. Our new scoring system including FDP levels could contribute to rapid diagnosis of the acute presentation of AIH without liver biopsy.

Influence of the culture medium on the production of nitric oxide and expression of inducible nitric oxide synthase by activated macrophages in vitro

Macrophages play an important role in immune and inflammatory responses, and have been extensively studied in vitro using culture media such as RPMI1640 medium, Dulbecco's modified Eagle medium (DMEM), and Ham's F-12 medium (F-12). We found that the activation phenotypes of a murine macrophage-like cell line, J774.1/JA-4, were obviously different in two distinct culture media (F-12 and DMEM), both of which were supplemented with 10% of the same fetal bovine serum (FBS). Among these phenotypes, nitric oxide (NO) production as well as inducible NO synthase (iNOS) expression, induced by lipopolysaccharide (LPS) and interferon-γ (IFN-γ), were remarkably different. iNOS expression was higher in the macrophages cultured in DMEM than in F-12 for 20h, while no significant differences were shown in NO production between in F-12 and DMEM. It might be the reason why DMEM have reduced NO production by the induced iNOS. Besides, O2−-generating activity, and production of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the activated macrophages were also different between the cultures in F-12 and DMEM. These results suggest that F-12 and DMEM contain certain components responsible for modification of macrophage activation processes and/or macrophage functions. Our present results provide evidence that the choice of culture medium is important in the study and analysis of macrophage activation.

IL-3 and GM-CSF in combination alters protein tyrosine kinase activity of splenic macrophages in leukemic mice.

Objectives: Murine macrophages were playing a key role against microbes and foreign particles as well as help in solid tumorigenesis in the host body. In this experiment we were trying to evaluate the protein tyrosine kinase (PTK) activity in macrophages from experimentally induced leukemic animal model.Methods: Balb/C mice were divided into four groups, two groups were challenged with N-N ethyl nitrosourea (ENU) and two groups remained without ENU challenged condition. After confirmation of leukemia induction, one normal and one ENU challenged groups were received rmIL-3 for 4 days followed by rmGM-CSF for 4 days. Disease was confirmed by histological studies of peripheral blood and bone marrow smear. PTK activity assay were done using universal protein tyrosine assay kit.Results: Protein tyrosine kinase (PTK) activity of macrophages was increased in leukemic animal significantly which were reduced after combination of IL-3 and GM-CSF treatment. IFN- ? level in blood serum were increased in leukemic mice and reduced after treatment as normal level. Conclusion: Results suggest that, in leukemia reduced macrophage number can be increased by IL-3 and GM-CSF administration in combination but PTK activity is not involved to increase the number of macrophages. PTK activity may be involved in macrophage activation process in Leukemic animal.

Time and Demand are Two Critical Dimensions of Immunometabolism: The Process of Macrophage Activation and the Pentose Phosphate Pathway.

A process is a function of time; in immunometabolism, this is reflected by the stepwise adaptation of metabolism to sustain the bio-energetic demand of an immune-response in its various states and shades. This perspective article starts by presenting an early attempt to investigate the physiology of inflammation, in order to illustrate one of the basic concepts of immunometabolism, wherein an adapted metabolism of infiltrating immune cells affects tissue function and inflammation. We then focus on the process of macrophage activation and aim to delineate the factor time within the current molecular context of metabolic-rewiring important for adapting primary carbohydrate metabolism. In the last section, we will provide information on how the pentose phosphate pathway may be of importance to provide both nucleotide precursors and redox-equivalents, and speculate how carbon-scrambling events in the non-oxidative pentose phosphate pathway might be regulated within cells by demand. We conclude that the adapted metabolism of inflammation is specific in respect to the effector-function and appears as a well-orchestrated event, dynamic by nature, and based on a functional interplay of signaling- and metabolic-pathways.

Vizantin Inhibits Endotoxin-Mediated Immune Responses via the TLR 4/MD-2 Complex

Vizantin has immunostimulating properties and anticancer activity. In this study, we investigated the molecular mechanism of immune activation by vizantin. THP-1 cells treated with small interfering RNA for TLR-4 abolished vizantin-induced macrophage activation processes such as chemokine release. In addition, compared with wild-type mice, the release of MIP-1β induced by vizantin in vivo was significantly decreased in TLR-4 knockout mice, but not in TLR-2 knockout mice. Vizantin induced the release of IL-8 when HEK293T cells were transiently cotransfected with TLR-4 and MD-2, but not when they were transfected with TLR-4 or MD-2 alone or with TLR-2 or TLR-2/MD-2. A dipyrromethene boron difluoride-conjugated vizantin colocalized with TLR-4/MD-2, but not with TLR-4 or MD-2 alone. A pull-down assay with vizantin-coated magnetic beads showed that vizantin bound to TLR-4/MD-2 in extracts from HEK293T cells expressing both TLR-4 and MD-2. Furthermore, vizantin blocked the LPS-induced release of TNF-α and IL-1β and inhibited death in mice. We also performed in silico docking simulation analysis of vizantin and MD-2 based on the structure of MD-2 complexed with the LPS antagonist E5564; the results suggested that vizantin could bind to the active pocket of MD-2. Our observations show that vizantin specifically binds to the TLR-4/MD-2 complex and that the vizantin receptor is identical to the LPS receptor. We conclude that vizantin could be an effective adjuvant and a therapeutic agent in the treatment of infectious diseases and the endotoxin shock caused by LPS.

Serum myeloid-related protein 8/14 complex is associated with microalbuminuria in patients with type 2 diabetes

Microalbuminuria (MA) is associated independently with cardiovascular risk and progression of renal disease in patients with diabetes and the normal population. MA is an accepted factor for microvascular defects, in particular in patients with diabetes, and is associated with inflammation. Activated transmigrating macrophages are key cells in these inflammatory processes. Based on the theory that myeloid-related protein 8/14 complex (MRP8/14) is secreted by transmigrating macrophages, we hypothesized that MA was accompanied by elevated MRP8/14 and investigated whether MA predicts MRP8/14 in patients with type 2 diabetes. A total of 86 men with type 2 diabetes were grouped according to urinary albumin excretion in normoalbuminuria and MA. Serum MRP8/14 levels were measured by enzyme-linked immunosorbent assay. Established cardiovascular risk factors were quantified in both groups and compared with urinary albumin excretion. Albuminuria (mg/day) was positively associated with MRP8/14 (r = 0.34) and systemic blood pressure (r = 0.33). Patients with type 2 diabetes and MA demonstrated significantly higher MRP8/14 levels than patients with normoalbuminuria [median (interquartile range), 1.24 (0.97-2.28) µg/ml versus 0.97 (0.67-1.35) µg/ml, p < 0.05]. Serum creatinine levels, systolic blood pressure (SBP), very low density lipoprotein levels and the incidence of hypertension and coronary artery disease were significantly higher in the group with MA. Both groups did not differ significantly in other cardiovascular risk factors. MA was an independent predictor of serum MRP8/14 levels (β = 0.454) as well as SBP (β = 0.625) and haemoglobin A1c (β = 0.322). Our data demonstrate that albumin excretion is associated with the process of macrophage activation determined by MRP8/14 levels. These data not only suggest tissue inflammation as a factor for elevated cardiovascular risk in patients with type 2 diabetes, they further point to a role of macrophage activation in this process.

Foetal-maternal junctions in placentome as an experimental model to study the effect of xenobiotics on the course of pregnancy in cows

Macrophages play an important role in immune and inflammatory responses, and have been extensively studied in vitro using culture media such as RPMI1640 medium, Dulbecco's modified Eagle medium (DMEM), and Ham's F-12 medium (F-12). We found that the activation phenotypes of a murine macrophage-like cell line, J774.1/JA-4, were obviously different in two distinct culture media (F-12 and DMEM), both of which were supplemented with 10% of the same fetal bovine serum (FBS). Among these phenotypes, nitric oxide (NO) production as well as inducible NO synthase (iNOS) expression, induced by lipopolysaccharide (LPS) and interferon-γ (IFN-γ), were remarkably different. iNOS expression was higher in the macrophages cultured in DMEM than in F-12 for 20 h, while no significant differences were shown in NO production between in F-12 and DMEM. It might be the reason why DMEM have reduced NO production by the induced iNOS. Besides, O2−-generating activity, and production of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the activated macrophages were also different between the cultures in F-12 and DMEM. These results suggest that F-12 and DMEM contain certain components responsible for modification of macrophage activation processes and/or macrophage functions. Our present results provide evidence that the choice of culture medium is important in the study and analysis of macrophage activation.

Defective Macrophage Migration in Gαi2- but Not Gαi3-Deficient Mice

Various heterotrimeric G(i) proteins are considered to be involved in cell migration and effector function of immune cells. The underlying mechanisms, how they control the activation of myeloid effector cells, are not well understood. To elucidate isoform-redundant and -specific roles for Gα(i) proteins in these processes, we analyzed mice genetically deficient in Gα(i2) or Gα(i3). First, we show an altered distribution of tissue macrophages and blood monocytes in the absence of Gα(i2) but not Gα(i3). Gα(i2)-deficient but not wild-type or Gα(i3)-deficient mice exhibited reduced recruitment of macrophages in experimental models of thioglycollate-induced peritonitis and LPS-triggered lung injury. In contrast, genetic ablation of Gα(i2) had no effect on Gα(i)-dependent peritoneal cytokine production in vitro and the phagocytosis-promoting function of the Gα(i)-coupled C5a anaphylatoxin receptor by liver macrophages in vivo. Interestingly, actin rearrangement and CCL2- and C5a anaphylatoxin receptor-induced chemotaxis but not macrophage CCR2 and C5a anaphylatoxin receptor expression were reduced in the specific absence of Gα(i2). Furthermore, knockdown of Gα(i2) caused decreased cell migration and motility of RAW 264.7 cells, which was rescued by transfection of Gα(i2) but not Gα(i3). These results indicate that Gα(i2), albeit redundant to Gα(i3) in some macrophage activation processes, clearly exhibits a Gα(i) isoform-specific role in the regulation of macrophage migration.

Abstract 5531: Administration of the most potent macrophage activating factor, GcMAF, to cancer patients eradicates a variety of cancers indiscriminately

Abstract Intratumor BCG administration eradicates local as well as metastasized tumors (e.g., skin cancer). Administration of BCG into noncancerous tissues, however, results in no effect on the tumors. Inflammation induced by BCG in normal tissues releases lysophospholipids that activate macrophages. Because cancerous tissues contain alkylphospholipids, BCG-induced inflammation of cancerous tissues produces alkyl-lysophospholipids and alkylglycerols that activate macrophages approximately 400 times more effective than lysophospholipids, implying that highly activated macrophages are tumoricidal. Inflammation-primed macrophage activation is the principal macrophage activation process that requires serum Gc protein (known as vitamin D-binding protein) and participation of B and T lymphocytes. A trisaccharide composed of N-acetylgalactosamine with dibranched galactose and sialic acid termini at 420 threonine residue of Gc protein is hydrolyzed by the β-galactosidase (Bgl) of inflammation-primed B cells and the Neu-1 sialidase of T cells to yield the macrophage activating factor (MAF), the protein with N-acetylgalactoamine as the remaining sugar. Thus, Gc protein is the precursor for the principal MAF. However, the MAF precursor activity of serum Gc protein of cancer patients was lost or reduced because Gc protein is deglycosylated by serum α-N-acetylgalactosaminidase (Nagalase) secreted from cancerous cells. Thus, serum Nagalase activity is proportional to tumor burden and serves as an excellent prognostic index. Deglycosylated serum Gc protein can not be converted to MAF, leading to immunosuppression. Stepwise treatment of purified serum Gc protein with immobilized β-galactosidase and sialidase generates probably the most potent MAF (termed GcMAF) ever discoverd that produces no side effect in humans. Intramuscular administration of 100 ng GcMAF activates systemic macrophages at maximal level with 100-fold increased ingestion index and 30-fold increased superoxide generating capacity in 6 hrs. These activated macrophages developed an enormous variation of receptors that recognize cell surface abnormality (known as tumor associated antigen, TAA) of a variety of cancer cells and become tumoricidal to a variety of cancers indiscriminately. When those cancer patients bearing breast, prostate, colorectal, stomach, liver, lung, esophagus, kidney, bladder, uterus or ovarian cancer, or melanoma, fibrosarcoma, leukemia, glioblastoma or mesothelioma were intramuscularly administered with 100 ng GcMAF/week, their tumors were eradicated in 16 – 54 weeks which is roughly proportional to their original tumor burden. The curative rate of adenocarcinomas is a biphasic pattern due to a mixture of highly undifferentiated and differentiated tumor cells while the curative rate of all other cancer types is linear. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5531. doi:10.1158/1538-7445.AM2011-5531

Effect of LPS, dsRNA or interferons on the phagocytosis of dying cells or mycobacteria by macrophages

Infection with intracellular pathogens can trigger a panel of innate immune responses including cell death. Coupled with phagocytosis this often leads to clearance of the invader. However, some pathogens use the process to disseminate and proliferate. During Mycobacterium marinum infection, dying infected macrophages recruit fresh ones to the site of granuloma formation. The recruited macrophages phagocytose infected cell remnants, get infected and die, thus ensuring efficient spread and multiplication of the pathogen. Maturation of granuloma, the characteristic lesions of tuberculosis, requires tumor necrosis factor (TNF) and interferon (IFN)-gamma and represents a stalemate between host and pathogen sufficient to arrest infection without eliminating the bacteria. Indeed, our macrophage / mycobacterial infection model demonstrates that virulent H37RvMycobacterium tuberculosis is more efficient in macrophage infection and killing than the attenuated Mycobacterium bovis BCG vaccine. Today it is still unclear whether the signal promoting macrophage engagement in phagocytosis is originating from a pathogen or the infected host, and whether the effect is general or target specific. Therefore, we used a quantitative cell line based assay to study the effects of PAMPs or cellular alarm signals on the phagocytic engagement and capacity of macrophages to engulf virulent or attenuated mycobacteria and dying cells. Our results demonstrate that pretreatment of macrophage like cells with double stranded RNA, lipopolysaccharide, type I or II IFN but not with TNF, can significantly increase their capacity to phagocytose apoptotic and necrotic cells but has little effect on the phagocytosis of free mycobacteria. Although this macrophage activation process is probably an innate immune response reinforcing the capacity of the host to dispose of dying infected cells, pathogens may exploit it for their propagation.

Activation process of macrophages afterin vitrotreatment of mouse lymphocytes with dodecylglycerol

Alkylglycerols, inflammation products of cancerous membrane lipids, efficiently activate macrophages. A brief in vitro treatment (30 min) of peritoneal cells (mixture of non-adherent and adherent cells) with a small amount (50 ng/ml) of synthetic dodecylglycerol (DDG) resulted in greatly enhanced Fc-receptor-mediated ingestion activity of macrophages. However, treatment of adherent cells (macrophages) alone with DDG produced no significant enhancement of macrophage ingestion activity, implying that macrophage activation requires a contribution of non-adherent cells. DDG-treated non-adherent cells were found to generate a macrophage-activating signal factor. Studies with a serum free-0.1% egg albumin-supplemented RPMI 1640 medium revealed that a serum factor is essential for macrophage activation process. Time course analysis of stepwise transfers of conditioned media of DDG-treated or untreated B cells and T cells revealed that DDG-treated B cells rapidly transmit a factor to untreated T cells which yield the ultimate macrophage-activating factor. This signal transmission among these cells for the macrophage activation process is too rapid to allow time for synthesis of inducible gene products. Thus, we hypothesized that a serum factor is modified by the pre-existing function of DDG-treated B cells and further modified by the pre-existing function of untreated T cells to yield macrophage-activating factor. This hypothesis was confirmed by the demonstration that DDG-treated splenic non-adherent cell ghosts modify a serum factor to yield macrophage-activating factor.

Temporal and spatiotemporal variations in a mathematical model of macrophage–tumor interaction

In the present paper we study a three-component mathematical model of tumor–immune system interaction. A number of solid tumors contain a high proportion of macrophages and these immune cells are known to have a remarkable impact on the progression and dormancy of such tumors. We assume these macrophages as the main immune system component facilitating tumor destruction. Stability criteria of the basic model around the steady state of coexistence are derived. Next, we consider the process of macrophage activation as non-instantaneous by using a distributed delay with a weak kernel and obtain a range for the macrophage death rate that ensures system stability. Finally, we incorporate the spatial irregularity of solid tumors by making the delay nonlocal. Analysis of the resulting spatiotemporal model gives a number of thresholds in terms of different system parameters that guarantee tumor stability. Numerical simulations are performed to justify analytical findings.

Hyperferritinemia as indicator for intravenous immunoglobulin treatment in reactive macrophage activation syndromes.

The underlying mechanisms of reactive macrophage activation syndromes (rMAS) are not understood in detail, and there is no specific treatment. This observational study was prompted by intravenous immunoglobulin (IVIG), dramatically halting two distinct rMAS episodes in the same patient. We evaluated the potential benefits of IVIG administration in treating fulminant rMAS and the usefulness of monitoring serum ferritin levels as an indication for emergency treatment with IVIG. Ten females and 10 males experiencing 22 episodes of rMAS were recruited on the basis of serum ferritin levels >or=10,000 microg/l and/or direct evidence of haemophagocytosis in 11 intensive care units in secondary and tertiary care hospitals in Switzerland between October 1993 and May 2000. In individual patients, serially measured ferritin was closely related to disease activity. Abrupt increases of up to >100,000 microg/l could be observed within hours. Rapid and profound beneficial effects of emergency IVIG treatment were seen in 12 episodes of rMAS accompanied by a prompt decrease of serum ferritin. IVIG produced partial or delayed improvements in 5 patients. No apparent effects were seen in 5 patients. IVIG was only successful if started early during the ferritin run-up to peak values. In conclusion, IVIG is effective in at least a subgroup of adult rMAS when started at the beginning of the macrophage activation process. The monitoring of serum ferritin levels might be helpful in detecting macrophage activation in order to commence IVIG treatment early enough.

Role of macrophage activation in the pathogenesis of Alzheimer's disease and human immunodeficiency virus type 1-associated dementia.

The structure and function of neurons are changed not only during development of the central nervous system but also in certain neurological disorders, such as Alzheimer's disease and human immunodeficiency virus type 1 (HIV-1) -associated dementia. Immunological activation and altered production of neurotoxins and neurotrophins by brain macrophages are thought to play an important role in neuronal structure and function. This review describes the clinical and pathological features of both Alzheimer's disease and HIV-1-associated dementia and tries to interpret the role of the macrophage and astrocytes therein. The consequences of activation of macrophages by amyloid-beta in Alzheimer's disease and HIV infection of macrophages in HIV-1-associated dementia and the similarities between these diseases will be discussed. Although the neuropathology of Alzheimer's disease and HIV-1-associated dementia differs, Alzheimer's disease is a cortical dementia and HIV-1-associated dementia is a subcortical dementia, the process of macrophage activation and the resulting pathways leading to neurotoxicity seem very similar. In both Alzheimer's disease and HIV-1-associated dementia, interaction of macrophages and astrocytes appear to play an important role.

The src family-selective tyrosine kinase inhibitor PP1 blocks LPS and IFN-gamma-mediated TNF and iNOS production in murine macrophages.

Tyrosine phosphorylation pathways are essential components of the process of macrophage activation and the resultant production of inflammatory mediators such as tumor necrosis factor (TNF) and nitric oxide (NO). Several lines of evidence suggest that members of the src family of protein tyrosine kinases play important roles in macrophage activation by gram-negative bacterial lipopolysaccharide (LPS) or the cytokine interferon-gamma (IFN-gamma), but targeted disruption of three members of the src family (hck, fgr, and lyn) in mice failed to demonstrate a requirement for these particular kinases in macrophage activation. We report that the pyrazolopyrimidine PP1, a src family-selective tyrosine kinase inhibitor, potently inhibits the production of TNF and inducible nitric oxide synthase (iNOS) in RAW 264.7 murine macrophages stimulated with LPS, rlFN-gamma, or LPS + rIFN-gamma. Furthermore, the tested concentrations of PP1 inhibit LPS- and rlFN-gamma-mediated tyrosine phosphorylation of the hck tyrosine kinase and its putative substrate, vav, but fail to block rlFN-gamma-mediated JAK2 tyrosine phosphorylation. These findings provide additional support for a model of macrophage activation involving one or more src-related kinases. Selective inhibitors of this signaling pathway should be studied in animal models of sepsis.