Overactivation Of Macrophages Research Articles

Schisandrin A suppresses lipopolysaccharide-induced inflammation and oxidative stress in RAW 264.7 macrophages by suppressing the NF-κB, MAPKs and PI3K/Akt pathways and activating Nrf2/HO-1 signaling.

Schisandrin A is a bioactive lignan occurring in the fruits of plants of the Schisandra genus that have traditionally been used in Korea for treating various inflammatory diseases. Although the anti-inflammatory and antioxidant effects of lignan analogues similar to schisandrin A have been reported, the underlying molecular mechanisms have remained elusive. In the present study, schisandrin A significantly suppressed the lipopolysaccharide (LPS)-induced production of the key pro-inflammatory mediators nitric oxide (NO) and prostaglandin E2 by suppressing the expression of inducible NO synthase and cyclooxygenase-2 at the mRNA and protein levels in RAW 264.7 macrophages. Furthermore, schisandrin A was demonstrated to reduce the LPS-induced secretion of pro-inflammatory cytokines, including tumor necrosis factor-α and interleukin-1β; this was accompanied by a simultaneous decrease in the respective mRNA and protein levels in the macrophages. In addition, the LPS- induced translocation of nuclear factor-κB (NF-κB), as well as activation of mitogen-activated protein kinases (MAPKs) and phosphatidylinositol-3 kinase (PI3K)/Akt pathways were inhibited by schisandrin A. Furthermore, schisandrin A significantly diminished the LPS-stimulated accumulation of intracellular reactive oxygen species, and effectively enhanced the expression of NF erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). These results suggested that schisandrin A has a protective effect against LPS-induced inflammatory and oxidative responses in RAW 264.7 cells by inhibiting the NF-κB, MAPK and PI3K/Akt pathways; these effects are mediated, at least in part, by the activation of the Nrf2/HO-1 pathway. Based on these results, it is concluded that schisandrin A may have therapeutic potential for treating inflammatory and oxidative disorders caused by over-activation of macrophages.

Melatonin modulates microsomal PGE synthase 1 and NF‐E2‐related factor‐2‐regulated antioxidant enzyme expression in LPS‐induced murine peritoneal macrophages

Increasing evidence demonstrates that melatonin regulates inflammatory and immune processes acting as both an activator and inhibitor of these responses. Nevertheless, the molecular mechanisms of its anti-inflammatory action remain unclear. Here we have characterized the cellular mechanisms underlying the redox modulation of LPS-stimulated inflammatory responses in murine peritoneal macrophages by melatonin to provide insight into its anti-inflammatory effects. Murine peritoneal macrophages were isolated and treated with melatonin in the presence or absence of LPS (5 μg·mL(-1) ) for 18 h. Cell viability was determined using sulforhodamine B assay and NO production was measured using the Griess reaction. Pro-inflammatory enzymes and transcription factors were detected by Western blotting. Without affecting cell viability, melatonin (12.5, 25, 50 and 100 μM) reduced the level of nitrites, inducible NOS (iNOS), COX-2 and microsomal PGE synthase-1 (mPGES1) protein, and p38 MAPK phosphorylation, and prevented NF-κB translocation. Furthermore, melatonin treatment significantly increased NF-E2-related factor 2 (Nrf2) and haem oxygenase 1 (HO1) protein levels in murine macrophages exposed to LPS. Melatonin reduced pro-inflammatory mediators and enhanced the expression of HO1 via NF-κB, p38 MAPK and Nrf2 cascade signalling pathways in murine macrophages. Thus, melatonin might be a promising target for diseases associated with overactivation of macrophages.

Shock State

Some patients with drug reaction with eosinophilia and systemic symptoms (DRESS) are probably admitted in intensive care unit (ICU), but data concerning their clinical features at admission are scarce. Therefore, in the present study, we used a clinical network of French intensivists to study the clinical features and evolution of DRESS patients hospitalized in ICU. A national, retrospective, multicenter study collected DRESS cases hospitalized in ICU for DRESS from 2000 to end of 2011. All files were analyzed through the RegiSCAR scoring system as "no," "possible," "probable," or "definite" DRESS. Patients were included only if they had a probable or definite DRESS. Demographic, hemodynamic, biological, and infectious data were recorded. Twenty-one patients were included. Hospital mortality was 10 (47%) of 21, and 16 of 21 patients had on admission a shock state necessitating vasopressor agents. Echocardiographic ejection fraction in shock patients was depressed (47% ± 13%). Mechanical ventilation was required in 13 of 21 cases. Hepatic failure was observed in 11 of 21 cases, acute renal failure in 18 of 20 cases, and lactic acidosis in 12 of 20 patients. Initial bacteriology was negative in all patients. Human herpesvirus reactivations were found in five of 15 cases. In conclusion, shock without bacteriological documentation associated with multiple organ failure is the most common presentation of DRESS at admission in ICU and is associated with a higher mortality than previously described.

A fraction of stem bark extract of Entada africana suppresses lipopolysaccharide-induced inflammation in RAW 264.7 cells

Ethnopharmacological relevanceEntada africana is a plant used in African traditional medicine for the treatment of stomachache, fever, liver related diseases, wound healing, cataract and dysentery. Aims of the studyThis study aimed at evaluating the anti-inflammatory activity of fractions of the stem bark extract of the plant using lipopolysaccharide (LPS)-induced inflammation in RAW 264.7 macrophages model. Materials and methodsThe crude extract was prepared using the mixture CH2Cl2/MeOH (1:1, v/v) and fractionated by flash chromatography using solvents of increasing polarity to obtain five different fractions. The effects of the fractions on the cells viability were studied by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and their inhibitory activity against LPS-induced nitric oxide (NO) production screened by Griess test. The most active fraction was further investigated for its effects on reactive oxygen species (ROS) production using flux cytometry, the expression of inducible nitric oxide synthase (iNOS), pro-and anti-inflammatory cytokines (IL1β, TNFα, IL6, IL10 and IL13) by RT-PCR, and the activity of the enzyme p38 MAPK kinase by enzyme-linked immunosorbent assay (ELISA). ResultsThe fractions presented no significant effect on the viability of macrophages at 100μg/ml after 24h incubation. The CH2Cl2/MeOH 5% (Ea5) fraction was found to be the most potent in inhibiting NO production with a half inhibition concentration (IC50)=18.36μg/ml, and showed the highest inhibition percentage (89.068%) in comparison with Baicalin (63.34%), an external standard at 50μg/ml. Ea5, as well as Baicalin significantly (P<0.05) inhibited the expression of TNFα, IL6 and IL1β mRNA, attenuated mRNA expression of inducible NO synthase in a concentration-dependent manner, stimulated the expression of anti-inflammatory cytokines (IL10 and IL13), and showed a 30% inhibition of the activity of p38 MAPK kinase. ConclusionThe results of the present study indicate that the fraction Ea5 of Entada africana possesses most potent in vitro anti-inflammatory activity and may contain compounds useful as a therapeutic agent in the treatment of inflammatory related diseases cause by over-activation of macrophages.

Ramalin inhibits LPS‐induced autophagic response in macrophages through the downregulation of iNOS expression

Activation of macrophages is essential for the host defense system and accumulating evidence suggests that autophagy is an important component in macrophage activity. Prolonged activation of macrophages, however, becomes detrimental and contributes to the progression of chronic inflammatory diseases with abnormal cell death. Therefore, controlling the overactivation of macrophages may be a new therapeutic strategy for various inflammatory diseases. Here we showed that ramalin, an antioxidant compound from the Antarctic lichen Ramalina terebrata, inhibited both LPS‐induced autophagy and iNOS in macrophages. To verify the role of NO in autophagy, we compared autophagy‐related gene expression in LPS‐stimulated and SNP‐stimulated macrophages by western blotting. Interestingly, ramalin did not suppress NO and autophagy in macrophages exposed to NO donor, SNP. In addition, inhibition of NO production by SMT significantly reduced LPS‐induced autophagy. These finding imply that ramalin might suppress LPS‐induced autophagy by inhibiting NO secretion. Ramalin also showed inhibitory effect on LPS‐induced NF‐κB and MAPK activation. Overall, these finding indicate that ramalin suppresses autophagy in LPS‐stimulated macrophages by preventing NO production and downregulating both NF‐κB and MAPK activation.

Inhibition of Pim-1 Kinase Ameliorates Dextran Sodium Sulfate-Induced Colitis in Mice

Pim-1 kinase is involved in the control of cell growth, differentiation and apoptosis. Recent evidence suggests that Pim kinases play a role in immune regulation and inflammation. However, the role of Pim-1 kinase in inflammatory bowel diseases (IBD) remains unclear. The aims of this study were to explore the role of Pim-1 kinase in the pathology of IBD and to assess whether inhibiting Pim-1 kinase may be of therapeutic benefit as a treatment regimen for IBD. Colitic mouse model was established by the induction of dextran sodium sulfate. The expression of Pim-1 in the colonic samples of control and colitic mice was examined. Furthermore, the mice were treated with Pim-1inhibitor (PIM-Inh), then the body weight and colon inflammation were evaluated, and the production of cytokines including IFN-γ, IL-4, TGF-β and IL-17 in colon tissues was determined by ELISA. The expression of T cell master transcription factors T-bet, ROR-γt, GATA-3 and Foxp3 and Nuclear factor κB (NF-κB) and inducible nitric oxide synthase in colon tissues was detected by real-time PCR and western blot. Finally, the effect of LPS on Pim-1 expression and the effects of PIM-Inh on LPS-induced upregualtion of p65 and TNF-α in RAW264.7 cells were examined by real-time PCR and western blot. Pim-1 expression was correlated with the degree of mucosal inflammation in vivo, and it was significantly induced by LPS in vitro. PIM-Inh had protective effects on acute colitis in vivo. Mechanistically, PIM-Inh reduced the proinflammatory immune response through the inhibition of the overactivation of macrophages and the down-regulation of excessive Th1- and Th17-type immune responses. Furthermore, PIM-Inh could skew T cell differentiation towards a Treg phenotype. Pim-1 kinase is involved in mucosal injury/inflammation and Pim-1 kinase inhibitor may provide a novel therapeutic approach for IBD.

A new treatment strategy for acute liver failure

Acute liver failure (ALF) is a syndrome defined by coagulopathy and encephalopathy and no effective treatments have been established, except for liver transplantation. However, considering the limited supply of donors, we should endeavor to prevent the progression of this syndrome in its early stage to improve the prognosis of patients with ALF. Recently, several authors have reported that over-activation of intrahepatic macrophages plays an important role in the progression of ALF and we have developed a new treatment method, transcatheter arterial steroid injection therapy (TASIT), to suppress macrophage activation. We have now used TASIT for 5 years and have found that TASIT is effective for patients with over-activation of macrophages in the liver but not for those with lesser activation of macrophages. Therefore, to identify the most appropriate patients for TASIT, we tried to categorize patients with ALF or acute liver injury according to markers for the degree of intrahepatic macrophage activation. This approach was helpful to select the appropriate treatment including liver transplantation. We believe that it is essential to analyze disease progression in each patient before selecting the most appropriate treatment.

A high prevalence of extreme hyperferritinemia in acute hepatitis patients

Although the mechanism underlying acute liver failure (ALF) has not been clarified, recent reports indicate overactivation of macrophages is involved in its progression. In diseases in which activated macrophages participate in the progression, elevated serum ferritin concentration counts among the characteristic laboratory findings. If activated macrophages play a key role in the development of ALF, serum ferritin levels might reflect the severity of acute liver injury. To confirm this, we evaluated the correlation between the serum ferritin concentration and other laboratory measurements in patients with acute hepatitis including ALF. One hundred consecutive patients with acute liver injury were enrolled, of whom 19 fulfilled the criteria for ALF. Serum ferritin concentrations correlated with serum alanine transferase activity as a whole. Interestingly, the correlation was strong in patients infected by hepatitis viruses, but weak in others. Although most patients with ALF had high levels of serum ferritin, not a few patients without ALF showed similar results. The serum ferritin level was generally increased in acute hepatitis patients, probably reflecting the degree of macrophage activation in the liver. Overactivation of macrophages appears to be essential, but not sufficient, for the development of ALF.

A new parameter using serum lactate dehydrogenase and alanine aminotransferase level is useful for predicting the prognosis of patients at an early stage of acute liver injury: A retrospective study

BackgroundAlthough most patients with severe acute hepatitis are conservatively cured, some progress to acute liver failure (ALF) with a high rate of mortality. Based on the evidence that over-activation of macrophages, followed by disturbance of the hepatic microcirculation, plays a key role in ALF, we hypothesized that the production of serum lactate dehydrogenase (LDH) might increase in the liver under hypoxic conditions and could be an indicator to discriminate between conservative survivors and fatal patients at an early stage.ResultsTo confirm this hypothesis, we developed a new parameter with serum alanine aminotransferase (ALT) and LDH: the ALT-LDH index = serum ALT/(serum LDH - median of normal LDH range). We analyzed retrospectively 33 patients suffering acute liver injury (serum ALT more than 1000 U/L or prothrombin time expressed as international normalized ratio over 1.5 at admission) and evaluated the prognostic value of the ALT-LDH index, comparing data from the first 5 days of hospitalization with the Model for End-Stage Liver Disease (MELD) score. Patients whose symptoms had appeared more than 10 days before admission were excluded from this study. Among those included, 17 were conservative survivors, 9 underwent liver transplantation (LT) and 7 died waiting for LT. We found a rapid increase in the ALT-LDH index in conservative survivors but not in fatal patients. While the prognostic sensitivity and specificity of the ALT-LDH index was low on admission, at day 3 they were superior to the results of MELD.ConclusionALT-LDH index was useful to predict the prognosis of the patients with acute liver injury and should be helpful to begin preparation for LT soon after admission.

Viral form of hemophagocytic syndrome with erythrodermal clinical picture: Case report

Hemophagocytic syndrome is patophysiological entity with proliferation and over-activation of macrophages, with hemophagocytosis and production of proinflammatory cytokines. It arises as hereditary forms, or acquired, during viral, autoimmune or malignant diseases, and is usually a disorder with fulminant course and high incidence of lethal outcome. The precise mechanism is not resolved; it is a consequence of cytokine storm generated by over-activated T cells and macrophages, due to defects in T cellular cytototoxic function and inadequate down-regulation of immune response. A male patient, 26 years old, previously healthy, is presented. Generalized exfoliative dermatitis and lymphadenomegalia had lasted for half a year before admission to the hospital. Hemophagocytosis in lymph gland histology was diagnostic, with T cellular immunohistochemical profile CD3+, CD5-, CD8/-, CD43+/-, CD45RO+, bcl-2+, and numerous CD68+ histiocytes. Apart from elevated titer of Adenovirus serology, other laboratory findings and bone marrow histology were within normal limits. Two weeks of oral antibiotic and topical skin corticosteroid therapy were followed by a rapid improvement of clinical features. Residual skin lesions, linear petechia and flares of pale pink erythema used to recur for the next half a year. During the follow up, two years later there was no lymph gland enlargement, skin rash, or other signs. The diagnosis of virus-associated hemophagocytic syndrome with mild clinical course and seemingly spontaneous improvement was established, although it did not fulfill all proposed diagnostic criteria. It is possible that it increased the clinical awareness for these mild forms in immune-competent patients could account for the improved recognition of atypical cases with favorable outcome.

Anti-inflammatory effects of short chain fatty acids in IFN-γ-stimulated RAW 264.7 murine macrophage cells: Involvement of NF-κB and ERK signaling pathways

The overactivation of macrophages causes abnormal cell death and chronic inflammatory diseases. Therefore, the modulation of macrophage-mediated cytotoxicity is expected to become a new therapeutic strategy for various inflammatory diseases. In this study, three types of short chain fatty acids (sodium butyrate (NaB), sodium phenylbutyrate (NaPB), sodium phenylacetate (NaPA)) were found to have anti-inflammatory effects in IFN-γ-stimulated RAW 264.7 cells. They inhibited the expression of iNOS, TNF-α, and IL-6 induced by IFN-γ, while they enhanced the expression of the anti-inflammatory cytokine, IL-10. Their potency as anti-inflammatory agents was in the order of NaB>NaPB>NaPA. Further mechanistic studies revealed these three agents to repress the DNA binding and transcriptional activities of NF-κB, which is an important modulator of inflammation. In addition, these agents repressed the IFN-γ-induced ERK1/2 phosphorylation without affecting the Jak/STAT activities. The potency of NF-κB and ERK inhibition was also in the order of NaB>NaPB>NaPA. The results suggest that the NF-κB and ERK signaling pathways are at least in part involved in the anti-inflammatory activities of these SCFAs. Considering that SCFAs are normally present in the body and have few side effects, they might be promising agents for the prevention and/or treatment of various inflammatory diseases.

Alterations in endothelial barrier permeability in multiple organs during overactivation of macrophages in rats.

Macrophage hyperactivity has been suggested to play an important role in septic complications and the development of multiple organ failure. Intraperitoneal administration of macrophage stimulants, e.g., zymosan, induce a systemic inflammatory response, with concomitant gut origin sepsis, and organ dysfunction. However, little is known about alterations in endothelial permeability during macrophage hyperactivation. In the present study, the effect of macrophage hyperactivation on endothelial permeability, assessed by 125I-labeled HSA and 51Cr-labeled EDTA, and the difference between cytolytic and noncytolytic inflammatory macrophages induced by i.p. injection of .25 or .50 mg/g of zymosan, concanavalin A (Con A) or thioglycollate medium (TM) diluted in 4 mL of paraffin, as well as the potential relationship with the doses used, were evaluated in the rat. Overactivation of cytolytic inflammatory macrophages induced a pronounced alteration in endothelial barrier permeability, characterized by a decrease in whole body plasma volume and an increase in whole body interstitial fluid volume, while overactivation of noncytolytic inflammatory macrophages only induced leakage of proteins and plasma to several of the organs studied. Macrophage activators, like zymosan, Con A and TM, exhibited varying effects on endothelial permeability related to the dose used. The results in the present study imply that overactivation of cytolytic inflammatory macrophages may play an important role in endothelial barrier injury and that zymosan possesses a more potent effect as compared to Con A when administered at the same dose.