Recent insights into the characteristics and role of peritoneal macrophages from ascites of cirrhotic patients

Macrophages are a diverse myeloid cell population involved in innate and adaptive immune responses,embryonic development,wound repair,and regulation of tissue homeostasis.These cells link the innate and adaptive immunities and are crucial in the development and sustainment of various inflammatory diseases.Macrophages are tissue-resident cells in steady-state conditions;however,they are also recruited from blood monocytes after local pathogen invasion or tissue injury.Peritoneal macrophages vary based on their cell complexity,phenotype,and functional capabilities.These cells regulate inflammation and control bacterial infections in the ascites of decompensated cirrhotic patients.Our recent work reported several phenotypic and functional characteristics of these cells under both healthy and pathological conditions.A direct association between cell size,CD14/CD16 expression,intracellular level of GATA-6,and expression of CD206 and HLA-DR activation/maturation markers,indicate that the large peritoneal macrophage CD14^(high)CD16^(high)subset constitutes the mature phenotype of human resident peritoneal macrophages during homeostasis.Moreover,elevated expression of CD14/CD16 is related to the phagocytic capacity.The novel large CD14^(high)CD16^(high)peritoneal subpopulation is increased in the ascites of cirrhotic patients and is highly sensitive to lipopolysaccharide(LPS)-induced activation,thereby exhibiting features of inflammatory priming.Thus,phosphorylation of ERK1/2,PKB/Akt,and c-Jun is remarkably increased in response to LPS in vitro,whereas that of p38 MAPK is reduced compared with the monocyte-derived macrophages from the blood of healthy controls.Furthermore,in vitro activated monocyte-derived macrophages from ascites of cirrhotic patients secreted significantly higher levels of IL-6,IL-10,and TNF-αand lower amounts of IL-1βand IL-12 than the corresponding cells from healthy donor’s blood.Based on these results,other authors have recently reported that the surface expression level of CD206 can be used to identify mature,resident,inflammatory peritoneal macrophages in patients with cirrhosis.Soluble CD206 is released from activated large peritoneal macrophages,and increased concentrations in patients with cirrhosis and spontaneous bacterial peritonitis(SBP)indicate reduced odds of survival for 90 d.Hence,the level of soluble CD206 in ascites might be used to identify patients with SBP at risk of death.In conclusion,peritoneal macrophages present in ascites of cirrhotic patients display multiple phenotypic modifications characterized by reduced ratio of cells expressing several membrane markers,together with an increase in the ratios of complex and intermediate subpopulations and a decrease in the classiclike subset.These modifications may lead to the identification of novel pharmaceutical targets for prevention and treatment of hepatic damage.

Lipopolysaccharide enhances the inhibition of NF-κB expression in NNK-mediated peritoneal macrophages

Objective： The aim of the study was to investigate the effect of lipopolysaccharide （LPS） on the expression of nuclear factor kappa B （NF-κB） in 4-（methylitrosamino）-1-（3-pyridyl）-1-butanone （NNK）-mediated primary mouse peritoneal macrophages in vitro. Methods： The activity of peritoneal rnacrophages treated with different concentrations of LPS was detected by MTT assay in rider to find the optimal concentration. Peritoneal macrophages were also treated with NNK （100-500 μM）, with or without LPS for 9 h. The expression of NF-κB was demonstrated via immunocytochemistry （ICC） and Western- blot, respectively. Results： The concentration of LPS at 25 μg/mL was found to be the optimal concentration to improve the activity of peritoneal macrophages （P 〈 0.01）. Simultaneously, LPS （25 μg/mL） increased the expression of NF-κB in both the nucleus and cytoplasm and facilitated transfer of NF-κB to the nucleus. NNK treatment significantly inhibited the expression of NF-κB in a concentration-dependent manner, among the LPS-stimulated or unstimulated peritoneal macrophages, especially when cotreated with LPS （25 μg/mL, P 〈 0.01 ）. Furthermore, NNK treatment （500 μM） with LPS yielded a significant decrease in NF-κB translocation to nucleus and inhibited the expression of NF-κB （P 〈 0.005）. Conclusion： LPS enhances the suppression of NF-κB expression in NNK-mediated mouse peritoneal macrophages, which may provide a theoretical basis for the inhibition of cancer.

Influence of whole peptidoglycan of bifidobacterium on cytotoxic effectors produced by mouse peritoneal macrophages

INTRODUCTIONBifidobacteria are physiologically beneficial bacteria which are perdominant in human intestine ,and possess the most important functions .They play an important role in maintaining microbial balance of the intestine .Furthermore , their presence is thought to be an important indication of health of the body [1-4].Whole peptidoglycan ( WPG) is the major component in the cell wall of bifidobacterium ,which is also a biological responsemodifier with nontoxic side dffcets.

THE EFFECTS OF RADIX SALVIAE MILTIORRHIZAE ON LIPID ACCUMULATION OF PEROXIDIZED LOW DENSITY LIPOPROTEIN IN MOUSE PERITONEAL MACROPHAGES ?LIPID ANALYSIS AND MORPHOLOGICAL STUDIES

Mouse peritoneal macrophages were incubated in DMEM with pox-LDL and Rradlx Salviae Miltiorrhizae (RSM) to investigate the effects of RSM on the internalization of peroxidized low density lipoprotein (pox-LDL) by using lipid analysis and electron microscopy. Lipid peroxide (LPO) concentrations were increased slightly in the medium after incubation of macrophages with normal LDL (n-LDL), while decreased significantly in the media after incubation of macrophages with pox-LDL. In the three groups with pox-LDL, it could be found that there was a dose-dependent decrease of concentrations of LPO and total cholesterol (TCH) in the two RSM groups, and the decrease in the two RSM groups was much greater than in the group without RSM. RSM accelerated a more decrease of LPO than cholesterol contents in the media containing pox-LDL. The ultrastructural studies also showed that RSM induced the accumulation of lipid droplets in the cytoplasm of mouse peritoneal macrophages. The results suggested that RSM could accelerate the phagocytosis and degradation of pox-LDL by macrophages.

Effects of quercetin on hepatocyte stimulating factor production by mouse peritoneal macrophages

Objective: To study the effects of quercetin on hepatocyte stimulating factor production from mouse peritoneal macrophages. Methods: Hepatocyte stimulating factor was evaluated by the amount of fibrinogen synthesized in Hep3B cells. Interleukin-6 activity was measured by B9 cell proliferation methyl thiazolyl tetrazolium colorimetric method. Hep3B cell supernatant fibrinogen was quantitated with ELISA. Results: LPS induced the synthesis of hepatocyte stimulating factor in mouse peritoneal macrophages, and hepatocyte stimulating factor promotes the synthesis of fibrinogen from Hep3B cells. Quercetin(5 to 40μmol/ L) inhibited the synthesis of hepatocyte stimulating factor stimulated by LPS. Quercetin(5 to 20μmol/ L) inhibited release of interleukin-6 from mouse peritoneal macrophages induced by 0. 5 g/ L fibrin fibrinogen degradation products. Conclusion: Quercetin inhibits the synthesis of hepatocyte stimulating factor in macrophages.

Inhibition of Emodin on LPS-induced Nitric Oxide Generation by Suppressing PLC-γ Phosphorylation in Rat Peritoneal Macrophages

Objective To investigate the inhibitory mechanism of emodin on lipopolysaccharide (LPS)-induced nitric oxide (NO) generation in rat peritoneal macrophages. Methods NO production and iNOS expression were measured through nitrite assay and Western blotting assay, respectively. NF-κB activity and nuclei P65 expression were estimated by dual-luciferase and Western blotting assay, respectively. Intracellular free Ca2+ ([Ca2+]i) was detected using the ratiometric fluorescent calcium indicator dye, Fura-2, and a microspectrofluorometer. PLC-γ phosporylation was analyzed by Western blotting assay. Results First, emodin was found playing active roles in suppressing LPS-induced NF-κB activation in rat peritoneal macrophages. Second, emodin down-regulated transient [Ca2+]i and could increase in NF-κB upstream signal. Finally, emodin suppressed phosphorylation of PLC-γ by LPS stimulation in the upstream of [Ca2+]i. Conclusion Suppression of PLC-γ phosphorylation is involved in emodin inhibiting NO generation by LPS stimulation in rat peritoneal macrophages.

Effects of Dachengqi (大承气)Decoction on the CytoplasmicFree Calcium in Peritoneal Macrophages of Miceof Bacteria Peritonitis

Effects of Dachengqi Decoction (DCQD) on the cytoplasmic free calcium ([Ca2+ ]i ) in theperitoneal macrophages (PM) of mice were measured with Ca2+ fluorescent indicator Fura-2/Am. Resultsshowed that the level of Ca2+ in PM of the mice with bacterial peritonitis induced by injecting Proteus vul-garis and Escherichia coli in resting was obviously increased compared with that of normal saline (NS) group.In the groups of DCQD, the mice after treated with DCQD for 2 days suffered from bacterial peritonitis, andthen they were continuously treated with DCQD for 3 days. Under this condition, the levels of PM[Ca2+ ] i,in resting or when the same doses of CaCI2 were added, were obviously decreased compared with that of theperitonitis model group (P < 0. 01 ) . Futhermore, the decrease of Ca2+ levels of DCQD groups was dose de-pendent. This result shows that DCQD has excellent protective effects on the bacterial peritonitis induced byProteus vulgaris or Escherichia coli .

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.

Inhibiting Effect of Lobenzarit Disodium on the Inter-leukin-1 Activity in Normal and in Adjuvant ArthritisKats and on the H_2O_2 Release from Rat Peritoneal Macro-phages

The effects of Lobenzarit disodium (CCA) upon the activity of interleukin-1(IL-1) of peritoneal macrophages(PMΦ)in normal and in adjuvant arthritis AA) rats and on the release of hydrogen peroxide(H_2O_2)of rat peritoneal macrophages were studied. CCA 10～200 μg/ml could inhibit IL-1activity in normal rat in vitro;CCA 10 and 50 mg/kg could depress the level of increased IL-1 in AA rats in vivo;CCA 5～100μg/ml could inhibit the release of H_2O_2 from rat PMΦin vitro.The results suggest that these effects could be one of the mechanisms of anti-inflammatory action of CCA.

Effects of shenmai injection on expression of TNF-α mRNA in peritoneal macrophages of scald mice

Objective To explore the effect of shenmai injection (SI) on expression of TNF-α mRNA in peritoneal macrophages (pMΦs) of scald mice.Methods BALB/c mice were inflicted with 11% of body surface area Ⅲ degree scald and injected intraperitoneally (ip) with SI daily for 5 days, and expression of TNF-α mRNA in pMΦs was determined by semi-quantitative RT-PCR.Results In scald mice, the expression of TNF-α mRNA in pMΦs increased significantly, but it was reduced obviously (P<0.01) after SI administration, while the livability was increased markedly (P<0.05).Conclusions For scald mice, the cause of death at early stage might be related to the high expression of TNF-α mRNA in pMΦs and the use of SI can decrease the death rate.

Bacteroides fragilis Supernatant Extracts Enriched in Phenylacetic Acid Induce a Cytotoxic Effect in Mammalian Cells

Bacteroides species are nearly half of the fecal flora community and some are host symbionts crucial to host nutrition and systemic immunity. Among Bacteroides species B. fragilis strains are considered to be the opportunistic ones, being the most isolated anaerobic bacteria in clinical samples. Cell-free supernatants of 65 B. fragilis strains were assayed and they were capable of inducing vacuolating phenotype on Vero cells lineage. The supernatant of the Bacteroides fragilis ATCC 23745 strain was elicited to have the strongest vacuolating effect on Vero cells monolayers and peritoneal macrophages. Some drastic cell alterations were observed, such as a general disorganization of cytoplasm and chromatin condensation, evidencing cell death. By transmission electron microscopy it was confirmed that the vacuoles observed were, in fact, swollen mitochondria. An immunocytochemical assay, TUNEL, was used to confirm this hypothesis and showed that Vero cells and peritoneal macrophages were dying by apoptotic process after exposition of B. fragilis cell-free supernatant. Physical analysis of the apoptotic factor has revealed properties similar to short-chain fatty acids. After gas chromatography and mass spectrometry analysis, phenylacetic acid (PA) was characterized as the major compound present in the most purified active fraction. We believe that the PA is responsible for the pro-apoptotic effect elicited by the supernatant of B. fragilis cultures.

Effects of Andrographolide on the Activation of Mitogen Activated Protein Kinases and Nuclear Factor-κ B in Mouse Peritoneal Macrophage-derived Foam Cells

Objective： To observe the effect of andrographolide on the activation of mitogen-activated protein kinases （MAPKs） and expression of nuclear factor- kB （NF-kB） in macrophage foam cells. Methods： The mouse peritoneal macrophages were cultured in the media in the presence of oxidized low-density lipoprotein （ox-LDL）, ox-LDL＋andrographolide, or neither （control）. The phosphorylation of MAPK molecules （p38MAPK, JNK, ERK1/2） and the expressions of NK- kB p65 were examined by Western blot. Results： As compared with cells in the control group, the expressions of phospho-p38 and NF- kB p65 were increased in the cells cultured with either ox-LDL or ox-LDL＋andrographolide （P〈0.01）, but attenuated significantly in the presence of ox-LDL＋ andrographolide when compared with ox-LDL （P〈0.05）. The phospho-JNK increased in the presence of either ox-LDL or ox-LDL＋andrographolide when compared with control cells （P〈0.01）, but no significant difference existed between ox-LDL and ox-LDL＋andrographolide （P〉0.05）. The expression of phospho-ERK1/2 was increased in the presence of ox-LDL compared with the control cells （P〈0.01）, but no significant differences existed between the cells cultured in the presence of ox-LDL＋andrographolide and the control medium （P〉0.05）. Conclusions： Andrographolide could inhibit the activation of ERK1/2, p38MAPK and NK-kB induced by ox-LDL in macrophage foam cells, which might be one of its mechanisms in preventing atherosclerosis.