Intracellular Macrophage Migration Inhibitory Factor Research Articles

NF-κB inhibition leads to increased synthesis and secretion of MIF in human CD4+T cells (48.2)

Abstract To examine the effects of NF-κB inhibition on the secretion of macrophage migration inhibitory factor (MIF) in CD4+ T cells. Isolated human CD4+ T cells were cultured with NF-κB inhibitors for 24 hrs. MIF levels were evaluated by intracellular FACs, ELISA, and real time PCR. The levels of intracellular O2-, H2O2, and glutathione were evaluated by intracellular FACs. The amounts of phosphorylated Akt and c-Jun were measured by Western blotting. Treatment of CD4+ T cells with NF-κB inhibitors resulted in a significant increase of MIF concentration in culture supernatants, MIF gene expression and O2- production and decrease of intracellular MIF, H2O2, and GSH. Treatment with LY294002, and SP600125 suppressed NF-κB inhibitors induced MIF mRNA expression and MIF secretion and inhibited parthenolide induced phosphorylation of Akt and c-Jun. Treatment with H2O2 also decreased the amounts of intracellular MIF protein and increased MIF level in the culture supernatant. NAC, an antioxidant precursor of GSH, inhibited parthenolide or H2O2 induced secretion of MIF. These results indicate inhibition of NF-κB leads to release of MIF through de novo synthesis of MIF and secretion of preformed MIF in CD4+ T cells through reactive oxygen species production. .

NF-κB inhibition leads to increased synthesis and secretion of MIF in human CD4 + T cells

To examine the effects of nuclear factor kappa B (NF-κB) inhibition on the secretion of macrophage migration inhibitory factor (MIF) in human CD4 + T cells. Isolated human CD4 + T cells were cultured for 24 h with pharmacological inhibitors of NF-κB including parthenolide, pyrrolidine dithiocarbamate, BAY 11-7082, gliotoxin, oridonin, andrographolide, and NF-κB shRNA. MIF concentration was measured by intracellular flow cytometry, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction. The intracellular concentrations O 2 −, H 2O 2, and glutathione were measured using the oxidation-sensitive fluorescent dyes dihydroethidium, dichlorodihydrofluorescein diacetate, and monochlorobimane, respectively. The amount of phosphorylated c-Jun was measured by Western blotting. Treatment of CD4 + T cells with NF-κB inhibitors significantly increased MIF concentration in culture supernatants, MIF gene expression, and O 2 − production, and decreased the intracellular concentrations of MIF, H 2O 2, and glutathione. Treatment with LY294002 (PI3K inhibitor) and SP600125 (JNK inhibitor) suppressed NF-κB inhibitor induced MIF mRNA expression and MIF secretion. LY294002 and SP600125 inhibited the parthenolide-induced phosphorylation of c-Jun. Treatment with H 2O 2 decreased the amount of intracellular MIF protein and increased MIF concentration in the culture supernatant. N-acetylcysteine, an antioxidant precursor of glutathione, inhibited the parthenolide-induced and H 2O 2-induced secretion of MIF. These results indicate that pharmacological inhibition of NF-κB causes the release of MIF through de novo synthesis of MIF and the secretion of preformed MIF in CD4 + T cells through the production of reactive oxygen species.

Knockdown of Macrophage Migration Inhibitory Factor Disrupts Adipogenesis in 3T3-L1 Cells

Obesity is a condition in which adipose tissue mass is expanded. Increases in both adipocyte size and number contribute to enlargement of adipose tissue. The increase in cell number is thought to be caused by proliferation and differentiation of preadipocytes. Macrophage migration inhibitory factor (MIF) is expressed in adipocytes, and intracellular MIF content is increased during adipogenesis. Therefore, we hypothesized that MIF is associated with adipocyte biology during adipogenesis and focused on the influence of MIF on adipogenesis. To examine the effects of MIF on adipocytes, MIF expression in 3T3-L1 preadipocytes was inhibited by RNA interference, and cell differentiation was induced by standard procedures. The triglyceride content of MIF small interfering RNA (siRNA)-transfected 3T3-L1 cells was smaller than that of nonspecific siRNA-transfected cells. In addition, MIF knockdown apparently abrogated increases in adiponectin mRNA levels during differentiation. Gene expression of peroxisome proliferator-activated receptor (PPAR)gamma, CCAAT/enhancer binding protein (C/EBP)alpha, and C/EBPdelta decreased with MIF siRNA transfection, but C/EBPbeta expression increased. Cell number and incorporation of 5-bromo-2-deoxyuridine into cells decreased from 1-3 d and from 14-20 h, respectively, after induction of differentiation in MIF siRNA-transfected cells, thus suggesting that MIF siRNA inhibits mitotic clonal expansion. Taken together, these results indicated that MIF regulates differentiation of 3T3-L1 preadipocytes, at least partially, through inhibition of mitotic clonal expansion and/or C/EBPdelta expression.

The microsatellite, macrophage migration inhibitory factor ‐794, may influence gene expression in human mononuclear cells stimulated with E. coli or S. pneumoniae

Polymorphisms within the gene encoding macrophage migration inhibitory factor (MIF) have been associated with susceptibility to inflammatory diseases such as rheumatoid arthritis and increased risk of developing sepsis. We investigated the effects of the MIF-173G>C polymorphism and the MIF-794 CATT microsatellite on MIF expression. These are in moderate linkage disequilibrium. Mononuclear cells from healthy donors were stimulated with bacterial pathogens associated with sepsis (Streptococcus pneumoniae or Escherichia coli ). MIF mRNA and protein levels were measured by real-time polymerase chain reaction and ELISA, respectively. Carriage of the C allele of MIF-173G>C or the 7 CATT repeat of the MIF-794 microsatellite correlated with lower basal and stimulated MIF mRNA levels. However, levels of intracellular and extracellular MIF protein were similar. This discordance between effects on MIF mRNA and protein was not explained by differential effects of genotype on stability of MIF mRNA (detected by actinomycin D mRNA chase). Gel shift assays revealed no differences in the profile of nuclear proteins from mononuclear cells bound by the G and C alleles of MIF-173G>C, but alleles at the microsatellite marker showed differential binding. Our data suggest that the MIF-794 CATT microsatellite influences transcription by differential binding of nuclear transcription factors. This may impact on inflammatory processes.

The levels of macrophage migration inhibitory factor as an indicator of disease activity and severity in adult-onset Still's disease

Objectives: This study investigated the levels of macrophage migration inhibitory factor (MIF) in adult-onset Still's disease (AOSD) and explored the role of this pro-inflammatory cytokine in the systemic inflammation of AOSD. Design and methods: Serum MIF levels were measured by ELISA in patients with AOSD and controls. Intracellular MIF production by peripheral blood leukocytes was detected by three-color flow cytometry. Results: Serum MIF levels were significantly increased in patients with AOSD. Serum MIF levels were significantly higher in AOSD patients with sore throat, myalgias, splenomegaly, or pleuritis, and were closely correlated with clinical disease severity and activity. Examined by flow cytometry, the intracellular MIF levels in monocytes and T-lymphocytes from AOSD patients were significantly higher than those from healthy subjects. Conclusion: These data represent the first demonstration of increased MIF expression in AOSD, and suggest that MIF may be an important marker for disease evaluation and monitoring.

Oxidoreductase macrophage migration inhibitory factor is simultaneously increased in leukocyte subsets of patients with severe sepsis

The oxidoreductase Macrophage Migration Inhibitory Factor (MIF) is discussed as a promising target for immunomodulatory therapy in patients with severe sepsis. Moreover, MIF expresses tautomerase as well as thiol-protein oxidoreductase activities and has a potential role in cellular redox homeostasis, apoptosis inhibition, endotoxin responsiveness as well as regulation of nuclear transcription factors. To further elucidate a potential role of intracellular MIF in severe sepsis, we assessed alterations of intracellular MIF content in peripheral blood leukocytes of patients with severe sepsis in comparison to healthy controls and non-septic patients after major surgery. Intracellular MIF was significantly elevated simultaneously in lymphocytes, B-cells, macrophages and granulocytes of patients with severe sepsis when compared to healthy control individuals (p < 0.05) and increased when compared to non-septic patients after major surgery. In parallel, plasma MIF levels were elevated in severe sepsis (p < 0.05). There was no difference of intracellular MIF in lymphocytes, B-cells, macrophages or granulocytes between surviving and non-surviving patients with severe sepsis (p > 0.05). However, in survivors LPS ex vivo stimulation increased MIF secretion but not in non-survivors of sepsis (p < 0.05). This finding underlines the role of intracellular MIF in inflammatory diseases. It suggests monitoring of intracellular MIF in further clinical and non-clinical research valuable.

The Potential Role of Macrophage Migration Inhibitory Factor on the Migration of Vascular Smooth Muscle Cells

Macrophage migration inhibitory factor (MIF) is known as a pro-inflammatory cytokine that regulates a broad spectrum of inflammatory reactions. MIF is expressed in vascular smooth muscle cells (VSMCs), and inhibition of the progression of atherosclerosis was observed in MIF-deficient atherosclerotic mice. However, the functional role of MIF in VSMCs has not been elucidated. The aim of this study was to investigate the role of MIF on the migration of VSMCs. Cultured rat A10 cells, derived from rat embryonic aortic smooth muscle cells, were stimulated with oxLDL, and the effect of MIF knockdown on oxLDL-mediated migration of A10 cells was analyzed. Intracellular MIF content was significantly increased and a marked increase of MIF concent-ration was observed in the supernatant of A10 cells treated with oxLDL. The migration of A10 cells was significantly accelerated by the stimulation of recombinant MIF in a dose-dependent manner. Notably, knockdown of intracellular MIF by siRNA abolished oxLDL-induced migration of A10 cells. These findings suggest that MIF acts on the migration of VSMCs in an autocrine and paracrine fashion. MIF appears to be a novel target for the prevention of cardiovascular events.

Lack of Macrophage Migration Inhibitory Factor Regulation Is Linked to the Increased Chronotropic Action of Angiotensin II in SHR Neurons

Macrophage migration inhibitory factor acts via its intrinsic thiol-protein oxidoreductase activity to negatively regulate the neuronal chronotropic actions of angiotensin II in normotensive rat neurons. Because the chronotropic action of angiotensin II is potentiated in spontaneously hypertensive rat neurons, we investigated whether this negative regulatory mechanism is absent in these rats. Angiotensin II (100 nM) elicited an approximately 89% increase in neuronal firing in Wistar-Kyoto rat hypothalamus and brain stem cultured neurons and an increase in intracellular macrophage migration inhibitory factor levels in the same cells. The chronotropic action of angiotensin II was significantly greater (approximately 212% increase) in spontaneously hypertensive rat neurons, but angiotensin II failed to alter macrophage migration inhibitory factor expression in these cells. Intracellular application of recombinant macrophage migration inhibitory factor (0.8 nM) or its specific neuronal overexpression via Ad5-SYN-MIF (1x10(7) infectious units) significantly attenuated the chronotropic action of angiotensin II in spontaneously hypertensive rat neurons, similar to results from Wistar-Kyoto rat neurons. In contrast, C60S-macrophage migration inhibitory factor (0.8 nM), which lacks thiol-protein oxidoreductase activity, failed to alter the chronotropic action of angiotensin II in neurons from either rat strain. Thus, whereas macrophage migration inhibitory factor has the potential to depress the chronotropic action of angiotensin II in spontaneously hypertensive rat neurons, it is unlikely that this regulatory mechanism occurs, because angiotensin II does not increase the expression of this protein. The lack of this regulatory mechanism may contribute to the increased chronotropic action of angiotensin II in spontaneously hypertensive rat neurons.

Ursolic acid promotes the release of macrophage migration inhibitory factor via ERK2 activation in resting mouse macrophages

Macrophage migration inhibitory factor (MIF) plays some pivotal roles in innate immunity and inflammation. Ursolic acid (UA), an anti-inflammatory triterpene carboxylic acid, was recently reported to induce the release of pro-inflammatory mediators in resting macrophages (Mϕ). We investigated the effects of UA on MIF protein release in resting RAW264.7 mouse Mϕ, and found that it decreased intracellular MIF protein levels and promoted the release of MIF into the culture media in dose- and time-dependent manners, without affecting mRNA levels. Further, the triterpene strikingly induced activation of mitogen-activated protein kinase kinase 1/2 (MEK1/2) and extracellular signal-regulated kinase 1/2 (ERK1/2) within 30 min, whereas no phosphorylation of p38 MAPK or JNK protein was observed. In addition, UA-promoted MIF release was significantly inhibited by PD98059, a MEK1/2 inhibitor, while siRNA for ERK2, but not ERK1, significantly decreased the amount of MIF protein released. These results suggest that UA triggers the release of intracellular MIF protein through the ERK2 activation.

Rapid and transient activation of the ERK MAPK signalling pathway by macrophage migration inhibitory factor (MIF) and dependence on JAB1/CSN5 and Src kinase activity

Macrophage migration inhibitory factor (MIF) is a 12.5 kD polypeptide that serves as a critical regulator of cell functions such as gene expression, proliferation or apoptosis. However, the signal transduction pathways through which MIF takes part in cellular regulation are only incompletely understood. MIF leads to CD74-dependent “sustained” activation of ERK1/2 MAPK, but MIF's role in “transient” ERK activation and the involved upstream pathways are unknown. Here we report that the transient ERK pathway was markedly activated by MIF. This effect involved the phosphorylation and activation of Raf-1, MEK, ERK, and Elk-1. Of note, rapid and transient ERK phosphorylation by MIF was measurable in MIF-deficient cells, suggesting that MIF acted in a non-autocrine fashion. Applying the inhibitor genistein, a tyrosine kinase (TPK) activity was identified as a critical upstream signalling event in MIF-induced transient ERK signalling. Experiments using the Src kinase inhibitor PP2 indicated that the involved TPK was a Src-type tyrosine kinase. A role for an upstream Src kinase was proven by applying Src-deficient cells which did not exhibit transient ERK activation upon treatment with MIF, but in which MIF-induced ERK signalling could be restored by re-expressing Src. Intriguingly, JAB1/CSN5, a signalosome component, cellular binding protein of MIF and regulator of cell proliferation and survival, had a marked, yet dual, effect on MIF-induced ERK signalling. JAB1 overexpression inhibited sustained, but not transient, ERK phosphorylation. By contrast, JAB1-knock-down by siRNA revealed that minimum JAB1 levels were necessary for transient activation of ERK by MIF. In conclusion, MIF rapidly and transiently activates the ERK pathway, an effect that has not been recognized previously. This signalling pathway involves the upstream activation of a Src-type kinase and is co-regulated by the cellular MIF binding protein JAB1/CSN5. Our study thus has unravelled a novel MIF-driven signalling pathway and an intricate regulatory system involving extra- and possibly intracellular MIF, and which likely critically participates in controlling cell proliferation and survival.

Macrophage Migration Inhibitory Factor Stimulates Angiogenic Factor Expression and Correlates With Differentiation and Lymph Node Status in Patients With Esophageal Squamous Cell Carcinoma

The objectives of this study were: 1) to examine the expression of macrophage migration inhibitory factor (MIF) in esophageal squamous cell carcinoma (ESCC); 2) to see if a relationship exists between MIF expression, clinicopathologic features, and long-term prognosis; and 3) to ascertain the possible biologic function of MIF in angiogenesis. MIF has been linked to fundamental processes such as those controlling cell proliferation, cell survival, angiogenesis, and tumor progression. Its role in ESCC, and the correlation of MIF expression and tumor pathologic features in patients, has not been elucidated. The expression of MIF in tumor and nontumor tissues was examined by immunohistochemical staining. Concentrations of MIF, vascular endothelial growth factor (VEGF), and interleukin-8 (IL-8) in patients' sera and in the supernatant of tumor cells culture were examined by ELISA. Correlations with clinicopathologic factors were made. In 72 patients with ESCC, intracellular MIF was overexpressed in esophagectomy specimens. The expression of MIF correlated with both tumor differentiation and lymph node status. The median survival in the low-MIF expression group (<50% positively stained cancer cells on immunohistochemistry) and high expression group (>/=50% positively stained cancer cells) was 28.3 months and 15.8 months, respectively (P = 0.03). The 3-year survival rates for the 2 groups were 37.7% and 12.1%, respectively. MIF expression was related to microvessel density; increased MIF serum levels also correlated with higher serum levels of VEGF. In addition, in vitro MIF stimulation of esophageal cancer cell lines induced a dose-dependent increase in VEGF and IL-8 secretion. These results demonstrate, for the first time, that human esophageal carcinomas express and secrete large amounts of MIF. Through its effects on VEGF and IL-8, MIF may serve as an autocrine factor in angiogenesis and thus play an important role in the pathogenesis of ESCC.

Macrophage Migration Inhibitory Factor: An Intracellular Inhibitor of Angiotensin II-Induced Increases in Neuronal Activity

Angiotensin II (Ang II) elicits Ang II type 1 receptor (AT1-R)-mediated increases in neuronal firing within the hypothalamus and brainstem that are ultimately responsible for physiological actions such as increased blood pressure and fluid intake. Although there is a growing literature on the intracellular mechanisms that mediate the actions of Ang II via AT1-R in neurons, little is known about the mechanisms that diminish or "switch-off" the neuronal chronotropic action of Ang II. In the present study, we identified macrophage migration inhibitory factor (MIF) as an intracellular inhibitor of the actions of Ang II in neurons. The evidence is as follows. First, Ang II, acting via AT1-R, increases the intracellular levels of MIF in neurons cultured from rat hypothalamus and brainstem. Second, elevation of intracellular MIF by Ang II prevents further chronotropic actions of this peptide. Third, intracellular application of exogenous recombinant MIF abolishes the Ang II-induced chronotropic action in neurons. Finally, intracellular application of the MIF peptide fragment MIF-(50-65), which harbors the thiol oxidoreductase property of the MIF molecule, mimics the inhibitory actions of MIF on Ang II-stimulated neuronal firing. Thus, this study is the first to demonstrate the existence of an intracellular negative regulator of Ang II-induced actions in neurons and indicates that MIF may act as a physiological brake for the chronotropic effects of Ang II in rat neurons.

Upregulation of macrophage migration inhibitory factor contributes to induced N-Myc expression by the activation of ERK signaling pathway and increased expression of interleukin-8 and VEGF in neuroblastoma.

Macrophage migration inhibitory factor (MIF) has been linked to fundamental processes such as control of cell proliferation, cell survival, angiogenesis, and tumor progression. The expression of MIF has been reported in several tumors. However, the precise role of MIF in tumor cells remains unclear. In the present study, we investigated the expression pattern and the function of MIF in neuroblastoma. Our results showed that intracellular MIF was upregulated in neuroblastoma tumor tissues and cell lines. MIF protein expression significantly correlated with the grade of tumor differentiation. In addition, we found that MIF induced a significant dose-dependent increase of vascular endothelial growth factor and interleukin-8 secretion. We also observed that an increased MIF expression level correlated with N-Myc protein (the N-myc oncogene product) expression in neuroblastoma tissues. MIF increased the expression of N-myc mRNA and N-Myc protein and induced N-Myc translocation from the cytoplasm to nucleus in neuroblastoma cell lines. MIF-induced N-Myc expression was found to be dependent on ERK signaling pathways. The inhibition of ERK activation reduced MIF-mediated N-Myc expression. These results suggest that MIF may contribute to the progression of neuroblastoma by (a) inducing N-Myc expression and (b) upregulating the expression of angiogenic factors.

Interferon-gamma induces macrophage migration inhibitory factor synthesis and secretion by tubular epithelial cells.

Macrophage migration inhibitory factor (MIF) promotes macrophage accumulation and leucocyte activation during inflammation. Macrophage migration inhibitory factor is upregulated in intrinsic renal cells in many types of kidney diseases, and has a pathogenic role in rat crescentic nephritis. However, little is known about the factors that regulate the production and secretion of MIF in kidney cells. In this study, we evaluated whether interferon-gamma (IFN-gamma), a cytokine implicated in the development of kidney disease and a potent inducer of MIF production in macrophages, could promote MIF synthesis and secretion from renal tubular epithelial cells. Northern blot analysis detected constitutive expression of MIF mRNA in rat tubular epithelial cells (NRK52E), which increased twofold after a 6-h stimulation with IFN-gamma. Macrophage migration inhibitory factor protein was found only in the cytoplasm of NRK52E cells. Following IFN-gamma stimulation, intracellular MIF in NRK52E cells was rapidly secreted with a maximal reduction of 50% after 20 min, which returned to normal levels after 2-4 h. Rapid secretion of MIF in response to IFN-gamma was also seen in rat mesangial cells. These findings indicate that IFN-gamma induces rapid secretion of MIF by tubular epithelial cells, and suggest that this may be an important mechanism leading to inflammatory cell accumulation and activation during kidney disease.

Secretion of macrophage migration inhibitory factor differs from interleukin-6 in hydrogen peroxide- and LPS-stimulated human fibroblasts

To investigate the mechanism for secretion of macrophage migration inhibitory factor (MIF) in cultured human fibroblasts, we compared it with the secretion of interleukin-6 (IL-6) after stimulation with lipopolysaccharides (LPS) and H 2O 2. MIF content of the medium of 2.0×10 6 cells/20 ml after 20 h culture of nonstimulated fibroblasts was 0.30±0.06 ng/ml, whereas LPS-stimulation (10 μg/ml) only led to a 1.5-fold increase as compared with the nonstimulated cells. In contrast, a significant increase of IL-6 was induced by LPS-stimulation (6048±488 pg/ml in LPS-stimulated cells vs. 58±36 pg/ml in control cells). On the other hand, higher concentrations of H 2O 2 (0.6–1.2 mM) caused an increase of MIF secretion into the culture medium irrespective of LPS-stimulation; with 1.2 mM H 2O 2-stimulation for 20 h, it was increased to 40-fold as compared with the nonstimulated cells. However, lower concentrations (0.1–0.4 mM) did not cause this. Interestingly, H 2O 2-stimulation not only failed to increase IL-6 production from fibroblasts, but also repressed induction of IL-6 by LPS-stimulation in a dose-dependent manner. Genistein, a tyrosine kinase inhibitor, and H-7, a protein kinase C inhibitor, also inhibited IL-6 secretion but not MIF secretion in both LPS- and H 2O 2-stimulated fibroblasts. From analysis of trypan blue exclusion, formazan formation, morphological changes, and intracellular MIF content by Western blotting, we found that MIF secretion by H 2O 2 seemed to be mainly due to cell death and subsequent leakage of intracellular MIF. Taken together, these results suggest that MIF secretion differs from IL-6 via LPS-mediated signaling pathways.

Secretion mechanism of macrophage migration inhibitory factor in hydrogen peroxide-and LPS-stimulated human fibroblasts differs from interleukin-6

In order to investigate the mechanism for secretion of macrophage migration inhibitory factor (MIF) in cultured human fibroblasts, we compared with the secretion of interleukin-6 (IL-6) as stimulated with lipopolysaccharides (LPS) and H2O2. MIF content of the medium of 2.0×106 cells/20 ml after 20 h culture of non-stimulated fibroblasts was 0.30±0.06 ng/ml, whereas LPS-stimulation (10μg/ml) led to increase only 1.5 fold as compared with the nonstimulated cells. In contrast, a significant increase of IL-6 was induced by LPS-stimulation (6048±488 pg/ml in LPS-stimulated cells vs 58±36 pg/ml in control cells) . On the other hand, the higher concentrations of H2O2 (0.6 mM-1.2 mM) caused an increase of MIF secretion into the culture medium irrespective of LPS-stimulation, showing that 1.2 mM H2O2-stimulation for 20 h was increased to 40 fold as compared with the nonstimulated cells. However, the lower concentrations (0.1 mM-0.4 mM) did not cause this. Interestingly, H2O2-stimulation not only failed to increase IL-6 production from fibroblasts, but also repressed induction of IL-6 by LPS-stimulation in a dose dependent manner. Genistein, a tyrosine kinase inhibitor and H-7, a protein kinase C inhibitor also inhibited IL-6 secretion but not MIF secretion in both LPS-and H2O2-stimulated fibroblasts. From analyses of trypan blue exclusion, formazan formation, morphological changes, and intracellular MIF content by Western blot, we found that MIF secretion by H2O2 seems to be mainly due to cell-death and subsequently leakage of intracellular MIF. Taken together, these results suggest that MIF secretion differs from IL-6 via LPS-mediated signaling pathways.

Intracellular distribution of macrophage migration inhibitory factor predicts the prognosis of patients with adenocarcinoma of the lung

Macrophage migration inhibitory factor (MIF) is known to be a proinflammatory cytokine and glucocorticoid-induced immunomodulator as well as a regulator of tumor growth. Although positive and negative effects of MIF on tumor cell growth have been reported, to the authors' knowledge the precise role of MIF in tumorigenesis remains unclear. In the current study the authors assessed expression of MIF protein and mRNA in lung adenocarcinomas with regard to patient prognosis. Immunohistochemical analysis was performed on tissue specimens surgically obtained from 74 patients with primary lung adenocarcinoma (American Joint Committee on Cancer pathologic Stages I, II, and IIIa). In addition, expression of MIF mRNA in the cancerous tissue was investigated using in situ hybridization. Patient prognosis was evaluated with regard to MIF expression levels and its distribution was analyzed with the Kaplan-Meier method. MIF mRNA and MIF protein were observed in the bronchial epithelium, alveolar epithelium, vascular smooth muscle, and alveolar macrophages in the normal lung tissue. In tumor tissue from lung adenocarcinoma specimens, both MIF mRNA and protein were observed at much higher levels than in the normal alveolar epithelium. MIF protein was observed diffusely in the cytoplasm of tumor cells in all tumor specimens examined. MIF protein also was observed in the nuclei of tumor cells from 59 patients (79.7%), whereas it was not observed in the nuclei of tumor cells from 15 patients (20.3%). The patients without nuclear MIF expression had a worse prognosis compared with those patients with MIF expression in the nuclei (P = 0.04). The results of the current study suggest that intracellular MIF distribution predicts patient prognosis in individuals with adenocarcinoma of the lung.

Expression and glucocorticoid regulation of macrophage migration inhibitory factor (MIF) in hippocampal and neocortical rat brain cells in culture

The biosynthesis of macrophage-migration inhibitory factor (MIF) and its regulation by the glucocorticoid dexamethasone was examined in cultured hippocampal and neocortical embryonic rat cells. Using immunohistochemical methods, MIF was found to be localized in neuronal as well as in non-neuronal cells. During the whole 12 day culture period, levels of MIF transcripts were detectable in both hippocampal and neocortical cells with an apparent increase in extracellular MIF protein at the later time points examined. Treatment with even very low concentrations (10 −11 M) of dexamethasone did not alter MIF mRNA levels but resulted in a rapid release of intracellular MIF protein within 1 and 4 h and a subsequent replenishment after 24 h. These data suggest that glucocorticoids do not affect the transcriptional activity of the MIF gene but induce the secretion of the protein, which suggests a close functional relationship of both mediators in the CNS.

Regulation of Macrophage Migration Inhibitory Factor (MIF) Expression by Glucose and Insulin in Adipocytes In Vitro

It has been reported that macrophage migration inhibitory factor (MIF) stimulated insulin secretion from pancreatic islet beta-cells in an autocrine manner, which suggests its pivotal role in the glucose metabolism. According to this finding, we evaluated MIF expression in cultured adipocytes and epididymal fat pads of obese and diabetic rats to investigate its role in adipose tissue. The murine adipocyte cell line 3T3-L1 was used to examine MIF mRNA expression and production of MIF protein in response to various concentrations of glucose and insulin. Epididymal fat pads of Otsuka Long-Evans Tokushima fatty (OLETF) and Wistar fatty rats, animal models of obesity and diabetes, were subjected to Northern blot analysis to determine MIF mRNA levels. MIF mRNA of 3T3-L1 adipocytes was up-regulated by costimulation with glucose and insulin. Intracellular MIF content was significantly increased by stimulation, whereas its content in the culture medium was decreased. When the cells were treated with cytochalasin B, MIF secretion in the medium was increased. Pioglitazone significantly increased MIF content in the culture medium of 3T3-L1 cells. However, MIF mRNA expression of both epididymal fat pads of OLETF and Wistar fatty rats was down-regulated despite a high plasma glucose level. The plasma MIF level of Wistar fatty rats was significantly increased by treatment with pioglitazone. We show here that the intracellular glucose level is critical to determining the MIF mRNA level as well as its protein content in adipose tissue. MIF is known to play an important role in glucose metabolism as a positive regulator of insulin secretion. In this context, it is conceivable that MIF may affect the pathophysiology of obesity and diabetes.

Effect of vitamin E on production of macrophage migration inhibitory factor (MIF) by macrophages.

Macrophage migration inhibitory factor (MIF), a putative cytokine involved in inflammatory and immune responses, was identified in rat peritoneal macrophages by Western blot analysis and its secretion into culture medium by enzyme-linked immunosorbent assay. To clarify the possibility of vitamin E as an immune modulator, we investigated the effect of vitamin E on MIF production in macrophages in response to calcium ionophore A23187 and lipopolysaccharide (LPS). Intraperitoneal injections of vitamin E (5 mg per rat) for 6 successive days resulted in a significant increase of alpha-tocopherol content in peritoneal macrophages. Alpha-tocopherol content of macrophages in vitamin E-treated rats was 478.3 +/- 90.7 ng/10(6) cells, whereas in control rats it was 1.5 +/- 0.5 ng/10(6) cells. For the control macrophages, total MIF content of the medium (2.5 x 10(6) cells/18 ml) without stimulation was 40.7 +/- 3.6 ng after 14 h culture, whereas stimulation with calcium ionophore A23187 (400 nM) and LPS (5.0 microg/ml) induced the elevation of MIF content to 65.9 +/- 7.5 ng and 74.3 +/- 10.4 ng, respectively (p < 0.05, n = 3). On the other hand, vitamin E-enriched macrophages without stimulation showed less MIF content (14.0 +/- 4.2 ng) than the control (p < 0.05, n = 3). Similarly, the increase of MIF of vitamin E-treated macrophages was significantly suppressed after stimulation with calcium ionophore A23187 or LPS, compared with the control macrophages (p < 0.01, n = 3). From analysis of intracellular MIF content by Western blot, we found no alteration of intracellular MIF content of vitamin E-macrophages, in contrast to the decreased content of control stimulated-macrophages, showing that vitamin E suppressed MIF secretion into the culture medium. Taken together, these results indicate that vitamin E may contribute to the regulation of inflammatory and immune responses through regulation of MIF secretion, possibly by modulating macrophage-membrane architecture.