Role of monocytes and macrophages in experimental and human acute liver failure

Acute liver failure (ALF) is a devastating clinical syndrome characterised by progressive encephalopathy, coagulopathy, and circulatory dysfunction, which commonly leads to multiorgan failure and death. Central to the pathogenesis of ALF is activation of the immune system with mobilisation of cellular effectors and massive production of cytokines. As key components of the innate immune system, monocytes and macrophages are postulated to play a central role in the initiation, progression and resolution of ALF. ALF in humans follows a rapidly progressive clinical course that poses inherent difficulties in delineating the role of these pivotal immune cells. Therefore, a number of experimental models have been used to study the pathogenesis of ALF. Here we consider the evidence from experimental and human studies of ALF on the role of monocytes and macrophages in acute hepatic injury and the ensuing extrahepatic manifestations, including functional monocyte deactivation and multiple organ failure.

Differential Effects of Alternative Glycoforms of IgG on Human Monocytes and Macrophages: Sialylated IgG Induces Novel Expression Signatures of Cell Surface Markers, Cytokines, and Chemokines

The effector functions elicited by the fragment crystallizable (Fc) region of immunoglobulin G (IgG) antibodies are subject to variation by the presence of terminal sialic acid (Sia) residues at asparagine-297 (Asn-297). We have previously shown that the sialic acid-containing (Sia+) fraction of intravenous immune globulin (IVIG) influences cell surface marker expression and cytokine/ chemokine secretion during the differentiation and maturation of human dendritic cells (DC). The present study examined the effects of Sia+ IgG on human peripheral blood mononuclear cell (PBMC)-derived monocyte and macrophage surface marker expression and cytokine/chemokine secretion. Sia+ IgG induced increased expression of CD80 and dendritic cell immunoreceptor (DCIR) on monocytes, whereas the expression of HLA-DR was decreased. In addition, the production of IL-6, TNFα, IL-1β, and CXCL1 by monocytes was profoundly increased by treatment with Sia+ IgG. Sia+ IgG also increased the expression of cell surface markers associated with macrophage polarization (e.g. CD40 and CD206) on monocytes. In macrophage-colony stimulating factor (MCSF) generated macrophages, Sia+ IgG induced increased production of numerous cytokines/ chemokines including IL-6, TNFα, CXCL1, and IL-10, and the expression of the macrophage surface marker CD163. Our data extended prior observations of Sia+ IgG on DC function and showed that Sia+ IgG was able to differentially modulate multiple pathways in monocytes and macrophages. Our data indicate that the Sia+ fraction of IVIG possesses the ability to influence inflammatory processes in multiple immune cell types and induces novel signatures in cell surface marker expression and cytokine/chemokine production.

Infiltration by monocytes of the central nervous system and its role in multiple sclerosis: reflections on therapeutic strategies

Mononuclear macrophage infiltration in the central nervous system is a prominent feature of neuroinflammation. Recent studies on the pathogenesis and progression of multiple sclerosis have highlighted the multiple roles of mononuclear macrophages in the neuroinflammatory process. Monocytes play a significant role in neuroinflammation, and managing neuroinflammation by manipulating peripheral monocytes stands out as an effective strategy for the treatment of multiple sclerosis, leading to improved patient outcomes. This review outlines the steps involved in the entry of myeloid monocytes into the central nervous system that are targets for effective intervention: the activation of bone marrow hematopoiesis, migration of monocytes in the blood, and penetration of the blood–brain barrier by monocytes. Finally, we summarize the different monocyte subpopulations and their effects on the central nervous system based on phenotypic differences. As activated microglia resemble monocyte-derived macrophages, it is important to accurately identify the role of monocyte-derived macrophages in disease. Depending on the roles played by monocyte-derived macrophages at different stages of the disease, several of these processes can be interrupted to limit neuroinflammation and improve patient prognosis. Here, we discuss possible strategies to target monocytes in neurological diseases, focusing on three key aspects of monocyte infiltration into the central nervous system, to provide new ideas for the treatment of neurodegenerative diseases.

Essential role of monocytes and macrophages in the progression of acute pancreatitis

Acute pancreatitis(AP) is an inflammatory condition of the pancreas caused by an imbalance in factors involved in maintaining cellular homeostasis.Earliest events in AP occur within acinar cells accompanied by other principal contributors to the inflammatory response i.e.the endothelial cells,immunocytes(granulocytes,monocytes/macrophages,lymphocytes) and neutrophils.Monocytes/macrophages are important inflammatory mediators,involved in the pathophysiology of AP,known to reside in the peritoneal cavity(in the vicinity of the pancreas) and in peripancreatic tissue.Recent studies suggested that impaired clearance of injured acini by macrophages is associated with an altered cytokine reaction which may constitute a basis for progression of AP.This review focuses on the role of monocytes/macrophages in progression of AP and discusses f indings on the inflammatory process involved.

Specific function and modulation of teleost monocytes/macrophages: polarization and phagocytosis

Macrophages exist in most tissues and play a variety of functions in vertebrates.Teleost fish species are found in most aquatic environments throughout the world and are quite diverse for a group of vertebrate animals.Due to whole genome duplication and en vironme ntal adaptati on,teleost monocytes/macrophages possess a variety of different functions and modulations compared with those of mammals.A deeper understanding of teleost monocytes/macrophages in the immune system will not only help develop teleost-specific methods of disease prevention but will also help improve our understanding of the various immune mechanisms in mammals.In this review,we summarize the differences in polarizati on and phagocytosis of teleost and mammalian macrophages to improve our understanding of the various immune mechanisms in vertebrates.

Mudskipper interleukin-34 modulates the functions of monocytes/macrophages via the colony-stimulating factor-1 receptor 1

Interleukin-34(IL-34)is a novel cytokine that plays an important role in innate immunity and inflammatory processes by binding to the colonystimulating factor-1 receptor(CSF-1R).However,information on the function of IL-34 in fish remains limited.In the present study,we identified an IL-34 homolog from mudskippers(Boleophthalmus pectinirostris).In silico analysis showed that the mudskipper IL-34(BpIL-34)was similar to other known IL-34 variants in sequence and structure and was most closely related to an orange-spotted grouper(Epinephelus coioides)homolog.BpIL-34 transcripts were constitutively expressed in various tissues,with the highest level of expression found in the brain.Edwardsiella tarda infection significantly up-regulated the mRNA expression of BpIL-34 in the mudskipper tissues.The recombinant mature BpIL-34 peptide(rBpIL-34)was purified and used to produce anti-rBpIL-34 IgG.Western blot analysis combined with PNGase F digestion revealed that native BpIL-34 in monocytes/macrophages(MOs/MФs)was N-glycosylated.In vitro,rBpIL-34 treatment enhanced the phagocytotic and bactericidal activity of mudskipper MOs/MФs,as well as the mRNA expression of pro-inflammatory cytokines like tumor necrosis factorα(BpTNF-α)and BpIL-1βin these cells.Furthermore,the knockdown of mudskipper CSF-1R1(BpCSF-1R1),but not mudskipper BpCSF-1R2,significantly inhibited the rBpIL-34-mediated enhanced effect on MO/MФfunction.In conclusion,our results indicate that mudskipper BpIL-34 modulates the functions of MOs/MФs via BpCSF-1R1.

Effects of Leptin on Expression of Acyl-coenzymeA:Cholesterol Acyltransferases-1 in Cultured Human Monocyte-macrophages

Summary: To investigate the effects of leptin on expression of acyl-coenzymeA:cholesterol acyltransferases-1 (ACAT-1) in monocyte-macrophage differentiation, human monocytic cells (THP-1) were cultured in RPMI 1640 and made to differentiate into macrophages under the incubation with phorbol myristate acetate (PMA) for 48 h. The cells were divided into 4 groups according to different intervention factors as follows: MCs cultured in RPMI1640 medium with 10 % FBS for 48 h served as MC group (control group), MCs cultured in medium with serum-free RPMI1640 containing 5 % BSA, 100 nmol/L PMA for 48 h as MP group, MCs cultured in RPMI1640 medium with 10 % FBS, 10 μmol/ml leptin for 48 h as leptin-MC group, and MCs cultured in medium with serum-free RPMI1640 containing 5 % BSA, 100 nmol/L PMA, and 10 μmol/ml leptin for 48 h as leptin-MP group. Immunocytochemistry, reverse transcription polymerase chain reaction (RT-PCR) and Western blot were performed, respectively, to observe the effects of leptin on expression of ACAT-1 in the monocyte-macrophage differentiation. Our results showed that expression of ACAT-1 protein and mRNA in MP-group is two times that in MC-group (P<0.05), and the expression of ACAT-1 protein and mRNA increased by up to 4 folds in leptin-MP group as compared with that of MC group (P<0.01). Thus, our results support the idea that expression of ACAT-1 increases more in cultured human macrophages than in monocytes, and leptin can significantly promote ACAT-1 expression. It was concluded that high expression of ACAT-1 may accelerate the development of human atherogenesis,and leptin might participate in atherogenesis by increasing expression of ACAT-1.

Role of macrophages and monocytes in hepatitis C virus infections

A number of studies conducted over many years have shown that hepatitis C virus(HCV)can infect a variety of cell types.In vivo infection of monocytes,macrophages,and dendritic cells by HCV has been frequently shown by a number of researchers.These studies have demonstrated replication of HCV by detecting the presence of both negative genomic strands and a variety of non-structural HCV proteins in infected cells.In addition,analyses of genome sequences have also shown that different cell types can harbor different HCV variants.Investigators have also done preliminary studies of which cellular genes are affected by HCV infection,but there have not yet been a sufficient number of these studies to understand the effects of infection on these cells.Analyses of in vitro HCV replication have shown that monocytes,macrophages and dendritic cells can be infected by HCV from patient sera or plasma.These studies suggest that entry and cellular locations may vary between different cell types.Some studies suggest that macrophages may preferentially allow HCV genotype 1 to replicate,but macrophages do not appear to select particular hypervariable regions.Overall,these studies agree with a model where monocytes and macrophages act as an amplification system,in which these cells are infected and show few cytopathic effects,but continuously produce HCV.This allows them to produce virus over an extended time and allows its spread to other cell types.

Effects of living and metabolically inactive mesenchymal stromal cells and their derivatives on monocytes and macrophages

Mesenchymal stromal cells (MSCs) are multipotent and self-renewing stem cellsthat have great potential as cell therapy for autoimmune and inflammatorydisorders, as well as for other clinical conditions, due to their immunoregulatoryand regenerative properties. MSCs modulate the inflammatory milieu by releasingsoluble factors and acting through cell-to-cell mechanisms. MSCs switch theclassical inflammatory status of monocytes and macrophages towards a nonclassicaland anti-inflammatory phenotype. This is characterized by an increasedsecretion of anti-inflammatory cytokines, a decreased release of pro-inflammatorycytokines, and changes in the expression of cell membrane molecules and inmetabolic pathways. The MSC modulation of monocyte and macrophage phenotypesseems to be critical for therapy effectiveness in several disease models, sincewhen these cells are depleted, no immunoregulatory effects are observed. Here,we review the effects of living MSCs (metabolically active cells) and metabolicallyinactive MSCs (dead cells that lost metabolic activity by induced inactivation) andtheir derivatives (extracellular vesicles, soluble factors, extracts, and microparticles)on the profile of macrophages and monocytes and the implications forimmunoregulatory and reparative processes. This review includes mechanisms ofaction exhibited in these different therapeutic appro-aches, which induce the antiinflammatoryproperties of monocytes and macrophages. Finally, we overviewseveral possibilities of therapeutic applications of these cells and their derivatives,with results regarding monocytes and macrophages in animal model studies andsome clinical trials.

MOSPD2 is a receptor mediating the LEAP-2 effect on monocytes/macrophages in a teleost,Boleophthalmus pectinirostris

Liver-expressed antimicrobial peptide 2(LEAP-2)is a cationic peptide that plays an important role in a host’s innate immune system.We previously demonstrated that mudskipper(Boleophthalmus pectinirostris)LEAP-2(BpLEAP-2)induces chemotaxis and activation of monocytes/macrophages(MO/MΦ).However,the molecular mechanism by which BpLEAP-2 regulates MO/MΦ remains unclear.In this study,we used yeast twohybrid cDNA library screening to identify mudskipper protein(s)that interacted with BpLEAP-2,and characterized a sequence encoding motile sperm domain-containing protein 2(BpMOSPD2).The interaction between BpLEAP-2 and BpMOSPD2 was subsequently confirmed by co-immunoprecipitation(Co-IP).Sequence analyses revealed that the predicted BpMOSPD2 contained an N-terminal extracellular portion composed of a CRAL-TRIO domain and a motile sperm domain,a C-terminal transmembrane domain,and a short cytoplasmic tail.Phylogenetic tree analysis indicated that BpMOSPD2 grouped tightly with fish MOSPD2 homologs and was most closely related to that of the Nile tilapia(Oreochromis niloticus).The recombinant BpMOSPD2 was produced by prokaryotic expression and the corresponding antibody was prepared for protein concentration determination.RNA interference was used to knockdown BpMOSPD2 expression in the mudskipper MO/MΦ,and the knockdown efficiency was confirmed by quantitative real-time polymerase chain reaction(qRT-PCR)and western blotting.Knockdown of BpMOSPD2 significantly inhibited BpLEAP-2-induced chemotaxis of mudskipper MO/MΦand BpLEAP-2-induced bacterial killing activity.Furthermore,knockdown of BpMOSPD2 inhibited the effect of BpLEAP-2 on mRNA expression levels of BpIL-10,BpTNFα,BpIL-1β,and BpTGFβ in MO/MΦ.In general,BpMOSPD2 directly interacted with BpLEAP-2,and mediated the effects of BpLEAP-2 on chemotaxis and activation of mudskipper MO/MΦ.This is the first identification of MOSPD2 as a receptor for LEAP-2.

Macrophage Inflammatory Protein-lalpha mediates Matrix Metalloproteinase-9 enhancement in human adherent monocytes fed with malarial pigment

Objective:To investigate the role of macrophage inflammatory protein-1alpha(MIP-1 alpha) in the detrimental enhancement of matrix mnetalloproteinase-9(MMP-9) expression,release and activity induced by phagocytosis of malarial pigment(haemozoin,HZ) in human monocytes. Methods:Human adherent monocytes were unfed/fed with native HZ for 2 h.After 24 hours. MIP-1 alpha production was evaluated by ELISA in cell supernatants.Alternatively.HZunfed /fed monocytes were treated in presence/absence of anti-human MIP-1 alpha blocking antibodies or recombinant human MIP-lalpha for 15 h(RNA studies) or 24 h(protein studies): therefore,MMP-9 mRNA expression was evaluated in cell lysatcs by Real Time RT-PCR,whereas proMMP-9 and active MMP-9 protein release were measured in cell supernatants by Western blotting and gelatin zvmography.Results:Phagocytosis of HZ by human monocytes increased production of MIP-1 alpha.mRNA expression of MMP-9 and protein release of proMMP-9 and active MMP-9.All the HZ-enbancing effects on MMP-9 were abrogated by anti-human MIP- 1 alpha blocking antibodies and mimicked by recombinant human MIP-l alpha.Conclusions: The present work suggests a role for MIP-lalpha in the HZ-dependent enhancement of MMP-9 expression,release and activity observed in human monocytes.higbligbtiug new detrimental effects of HZ-triggered proinflammatory response by phagocytic cells in falciparum malaria.

Adult endothelial progenitor cells from human peripheral blood maintain monocyte/macrophage function throughout in vitro culture

Mononuclear cells （MNCs） isolated from peripheral blood by density gradient centrifugation were plated on human fibronectin-coated culture plates and cultured in EGM-2 medium. Attached spindle-shaped cells, reported as endothelial progenitor cells （EPCs） by some investigators, had elongated from adherent round cells, but had not proliferated from a small number of cells as supposed previously. The growth curve of the primary EPCs showed that the cells had little proliferative capacity. Flow cytometry analysis showed that the cells could express some of the endothelial lineage markers, while they could also express CD 14, which is considered a marker of monocyte/macrophage lineages throughout culture. In endothelial function assays, the cells demonstrated a lower level of expression of eNOS than mature endothelial cells in the reverse transcription-polymerase chain reaction and did not show an ability to develop tube-like structures in angiogenesis assay in vitro. In this study, we identified the monocytoid function of EPCs by the combined Dillabeled acetylated low-density lipoprotein （Dil-Ac-LDL） and Indian ink uptake tests. All the cells were double positive for Dil- Ac-LDL and Indian ink uptake at days 4, 14 and 28 of culture, which means the EPCs maintained monocytoid function throughout the culture. Therefore, although adult EPCs from peripheral MNCs have some endothelial lineage properties, they maintain typical monocytic function and have little proliferative capacity.

Monocyte and macrophage function in respiratory viral infections

Pulmonary macrophages,such as tissue-resident alveolar and interstitial macrophages and recruited monocyte-derived macrophages,are the major macrophages present in the lungs during homeostasis and diseased conditions.While tissue-resident macrophages act as sentinels of the alveolar space and play an important role in maintaining homeostasis and immune regulation,recruited macrophages accumulate in the respiratory tract after acute viral infections.Despite sharing similar anatomical niches,these macrophages are distinct in terms of their origins,surface marker expression,and transcriptional profiles,which impart macrophages with distinguished characteristics in physi-ological and pathophysiological conditions.In this review,we summarize the current view on these macrophage populations,their shared functions,and what makes them distinct from each other in the context of homeostasis andrespiratoryviral infections.

Super-resolution immunohistochemistry study on CD4 and CD8 cells and the relation to macrophages in human cochlea

Recently, the human cochlea has been shown to contain numerous resident macrophages under steady-state. The macrophages accumulate in the stria vascularis, among the auditory nerves, and are also spotted in the human organ of Corti. These macrophages may process antigens reaching the cochlea by invasion of pathogens and insertion of CI electrode. Thus, macrophages execute an innate, and possibly an adaptive immunity. Here, we describe the molecular markers CD4 and CD8 of T cells, macrophage markers MHCⅡ and CD11b, as well as the microglial markers TEME119 and P2Y12, in the human cochlea. Immunohistochemistry and the advantageous super-resolution structured illumination microscopy(SR-SIM) were used in the study. CD4^+ and CD8^+ cells were found in the human cochleae. They were seen in the modiolus in a substantial number adjacent to the vessels, in the peripheral region of the Rosenthal's canal, and occasionally in the spiral ligament. While there are a surprisingly large number of macrophages in the stria vascularis as well as between the auditory neurons,CD4^+ and CD8^+ cells are hardly seen in these areas, and neither are seen in the organ of Corti. In the modiolus,macrophages, CD4^+ and CD8^+ cells appeared often in clusters. Interaction between these different cells was easily observed with SR-SIM, showing closely placed cell bodies, and the processes from macrophages reaching out and touching the lymphocytes. Otherwise the CD4^+ and CD8^+ cells in human cochlear tissue are discretely scattered. The possible roles of these immune cells are speculated.

Streptococcus mutans activates the AIM2, NLRP3 and NLRC4 inflammasomes in human THP-1 macrophages

Streptococcus mutans(S. mutans), a major aetiologic agent of dental caries, is involved in systemic diseases, such as bacterial endocarditis, if it enters the bloodstream through temporary bacteraemia. Interleukin(IL)-1β, a proinflammatory cytokine, is related to the host defences against pathogens, and its synthesis, maturation, and secretion are tightly regulated by the activation of the inflammasome, an inflammatory signalling complex. This study examined the signalling mechanism of IL-1β secretion and the inflammasome pathway induced by S. mutans to explain the molecular mechanism through which systemic infection by oral streptococci can occur. After infection of THP-1 cells with S. mutans, the expression of inflammasome components was detected using various methods. S. mutans induced IL-1β secretion via caspase-1 activation, and S. mutans-induced IL-1β secretion required absent in melanoma(AIM2), NLR family pyrin domain-containing 3(NLRP3) and NLR family CARD domain-containing 4(NLRC4)inflammasome activation. In particular, the S. mutans-induced NLRP3 inflammasome was mediated by adenosine triphosphate(ATP) release, potassium depletion and lysosomal damage. Our study provides novel insight into the innate immune response against S. mutans infection.

Infection and Immunity of Herpes Simplex Virusin the Culture System sof Lym phocytes and Monocyte-Macrophages

The study was made by the method of experimental infection using cultured cells in vitro. The characteristic of HSV infection of the cells and the effects of immunity factors on the infection were analyzed by cytopathic effect, double antibodies sandwich ELISA for immunoglobulin yield, hemolytic plaque assay for specific SRBC antibody forming cells, microcytopathy assay for viral titer, IFA for viral antigen and PCR for viral DNA.The results were as follows: ①A series of models of HSV infection were established, including the model of HSV 1 persistent infection of Raji cells, the model of acute and cytocidal HSV 1 infection of HSB\-2 cells, the models of temporary persistent HSV 1 infection of LPS stimulated U\-\{937\} cells and murine peritoneal macrophages and the models of inhibitions both of IgG synthesis and specific SRBC antibody production by HSV 1 infection of human tonsillar lymphocytes activated by PWM stimulating. ②According to the characteristic of HSV infection of lymphocyte and monocyte macrophage, it was reasonable that stimulating with antigen, mitogen, LPS, or inflammatory factors might make lymphocytes and/or monocyte macrophages become permissive cells of replicative HSV infection, or might activate the latent virus, resulting in HSV dissemination by blood circulation. ③It was proved that IFN α, IFN γ, TNF, M CSF, GM CSF and IL 3 have an inhibitory effect on HSV replication in lymphocyte and monocyte macrophage, respectively and reversed the replicative enhancement activity of LPS, suggesting that applications of these immunity factors favour lymphocytes and monocyte macrophages with a resistance to HSV replicative infection and with an inhibition of latent virus reactivation in vivo, and therefore, it might be helpful for preventing the virus from dissemination by blood circulation.\;

Studies on the Electron Microscopic Localization of Con A and WGA Receptors in Human Peritoneal Macrophages

The electron microscopic topology of Con A and WGA receptors was investi-gated in human peritoneal macrophagcs by utilizing avidin-gold colloids.Our observa-tions confirmed that both the receptors were distributed on the cell membranes,yet thereceptor expression showed variations among the individual cells.Some cells had abun-dant receptors,while others had only few receptors.The data obtained in the presentstudy indicate that human peritoneal macrophages may be a functionally andbiochemically heterogenous population,and the study may also serve as a theorcticalreference for future clinical exploitation of human peritoneal macrophages.

Malarial pigment does not induce MMP-2 and TIMP-2 protein release by human monocytes

Dear editor, In the recent years growing evidence on the involvement of human matrix metalloproteinases(MMPs) and tissue inhibitors of metalloproteinases(TIMPs) in cerebral malaria (CM) has been reported[1]and a role for malarial pigment haemozoin(HZ) has been proposed[2,3].In a recent work my group showed that in human microvascular endothelial

Inhibition of matrix metalloproteinase-9 secretion by dimethyl sulfoxide and cyclic adenosine monophosphate in human monocytes

BACKGROUND Matrix metalloproteinases(MMPs),including MMP-9,are an integral part of the immune response and are upregulated in response to a variety of stimuli.New details continue to emerge concerning the mechanistic and regulatory pathways that mediate MMP-9 secretion.There is significant evidence for regulation of inflammation by dimethyl sulfoxide(DMSO)and 3',5'-cyclic adenosine monophosphate(cAMP),thus investigation of how these two molecules may regulate both MMP-9 and tumor necrosis factorα(TNFα)secretion by human monocytes was of high interest.The hypothesis tested in this study was that DMSO and cAMP regulate MMP-9 and TNFαsecretion by distinct mechanisms.AIM To investigate the regulation of lipopolysaccharide(LPS)-stimulated MMP-9 and tumor necrosis factorαsecretion in THP-1 human monocytes by dimethyl sulfoxide and cAMP.METHODS The paper describes a basic research study using THP-1 human monocyte cells.All experiments were conducted at the University of Missouri-St.Louis in the Department of Chemistry and Biochemistry.Human monocyte cells were grown,cultured,and prepared for experiments in the University of Missouri-St.Louis Cell Culture Facility as per accepted guidelines.Cells were treated with LPS for selected exposure times and the conditioned medium was collected for analysis of MMP-9 and TNFαproduction.Inhibitors including DMSO,cAMP regulators,and anti-TNFαantibody were added to the cells prior to LPS treatment.MMP-9 secretion was analyzed by gel electrophoresis/western blot and quantitated by ImageJ software.TNFαsecretion was analyzed by enzyme-linked immuno sorbent assay.All data is presented as the average and standard error for at least 3 trials.Statistical analysis was done using a two-tailed paired Student t-test.P values less than 0.05 were considered significant and designated as such in the Figures.LPS and cAMP regulators were from Sigma-Aldrich,MMP-9 standard and antibody and TNFαantibodies were from R&D Systems,and amyloid-βpeptide was from rPeptide.RESULTS In our investigation of MMP-9 secretion from THP-1 human monocytes,we made the following findings.Inclusion of DMSO in the cell treatment inhibited LPSinduced MMP-9,but not TNFα,secretion.Inclusion of DMSO in the cell treatment at different concentrations inhibited LPS-induced MMP-9 secretion in a dosedependent fashion.A cell-permeable cAMP analog,dibutyryl cAMP,inhibited both LPS-induced MMP-9 and TNFαsecretion.Pretreatment of the cells with the adenylyl cyclase activator forskolin inhibited LPS-induced MMP-9 and TNFαsecretion.Pretreatment of the cells with the general cAMP phosphodiesterase inhibitor IBMX reduced LPS-induced MMP-9 and TNFαin a dose-dependent fashion.Pre-treatment of monocytes with an anti-TNFαantibody blocked LPSinduced MMP-9 and TNFαsecretion.Amyloid-βpeptide induced MMP-9 secretion,which occurred much later than TNFαsecretion.The latter two findings strongly suggested an upstream role for TNFαin mediating LPS-stimulate MMP-9 secretion.CONCLUSION The cumulative data indicated that MMP-9 secretion was a distinct process from TNFαsecretion and occurred downstream.First,DMSO inhibited MMP-9,but not TNFα,suggesting that the MMP-9 secretion process was selectively altered.Second,cAMP inhibited both MMP-9 and TNFαwith a similar potency,but at different monocyte cell exposure time points.The pattern of cAMP inhibition for these two molecules suggested that MMP-9 secretion lies downstream of TNFαand that TNFαmay a key component of the pathway leading to MMP-9 secretion.This temporal relationship fit a model whereby early TNFαsecretion directly led to later MMP-9 secretion.Lastly,antibody-blocking of TNFαdiminished MMP-9 secretion,suggesting a direct link between TNFαsecretion and MMP-9 secretion.

Transient over-expression of human papillomavirus type 16 E6 protein down-regulate the secretion of TNF-αor IL-1β LPS-induced from macrophages

In order to provide the experimental basis for the further studies on the oncogenic mechanism of the E6 protein from human papillomavirus type 16 （HPV16）, the eukaryotic expression vector pcDNA3.1 （-）/E6 was used for the study on the effect of E6 protein to influence the secretory activity of LPS-induced 3MP-1-macrophages, and the reconstructed plasmid pcDNA3.1 （-）/E6 was transfected into THP-1-macrophages. The expression of E6 gene was assayed in macrophage lysates by using Western blot analysis and the level of TNF-α or IL-1β was examined by ELISA. All of data were analyzed by SPSS12.0. As demonstrated by Western blot analysis, the expression of E6 protein with a molecular weight of about 18 kDa by plasmid pcDNA3.1 （-）/E6 in THP-1-macrophages could be detected. However, as demonstrated by ELISA assay, the level of TNF-α or IL-1β in lysates of THP-1-macrophages showed an obvious difference between the pcDNA3.1 （-）/E6 group and the LPS control group or the pcDNA3.1 （-） control group （P 〈 0.01）, but no significant difference existed between pcDNA3.1 （-） control group and LPS control group （ P 〉 0.05）. All these results illustrate that the transient over-expression of HPV6 E6 protein reduces the production of TNF-α and IL-1β induced by LPS in THP-1-macrophages.