Regulatory role for macrophage migration inhibitory factor in acute respiratory distress syndrome

Acute lung injury induced by lipopolysaccharide is independent of complement activation

Although acute lung injury (ALI) is an important problem in humans, its pathogenesis is poorly understood. Airway instillation of bacterial LPS, a known complement activator, represents a frequently used model of ALI. In the present study, pathways in the immunopathogenesis of ALI were evaluated. ALI was induced in wild-type, C3(-/-), and C5(-/-) mice by airway deposition of LPS. To assess the relevant inflammatory mediators, bronchoalveolar lavage fluids were evaluated by ELISA analyses and various neutralizing Abs and receptor antagonists were administered in vivo. LPS-induced ALI was neutrophil-dependent, but it was not associated with generation of C5a in the lung and was independent of C3, C5, or C5a. Instead, LPS injury was associated with robust generation of macrophage migration inhibitory factor (MIF), leukotriene B(4) (LTB4), and high mobility group box 1 protein (HMGB1) and required engagement of receptors for both MIF and LTB4. Neutralization of MIF or blockade of the MIF receptor and/or LTB4 receptor resulted in protection from LPS-induced ALI. These findings indicate that the MIF and LTB4 mediator pathways are involved in the immunopathogenesis of LPS-induced experimental ALI. Most strikingly, complement activation does not contribute to the development of ALI in the LPS model.

Up-regulation of macrophage migration inhibitory factor induced by endotoxin in experimental otitis media with effusion in mice

CONCLUSION

Injection of endotoxin into the middle ear causes production of macrophage migration inhibitory factor (MIF) in an experimental mouse model of otitis media with effusion (OME). Down-regulation of MIF may become a new approach for the management of OME.

OBJECTIVE

To determine the role of MIF in OME.

MATERIALS AND METHODS

Mice were divided into two groups and their middle ears were injected with either endotoxin or phosphate-buffered saline (PBS). Mice were sacrificed at 6 h, 12 h, or 1, 3, 7, or 14 days after injection and concentrations of MIF, interleukin-1 beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) in middle ear effusions were measured by enzyme-linked immunosorbent assay.

RESULTS

Concentrations of MIF in the endotoxin group at 1 day and 3 days were significantly higher than in the PBS control group. Concentrations of IL-1beta in the endotoxin group at 6 h, 12 h, 1 day, and 3 days were significantly higher than in controls. Concentrations of TNF-alpha in the endotoxin group at 1 day and 3 days were significantly higher than in controls. Concentration of MIF in the endotoxin group was positively correlated with that of IL-1beta and TNF-alpha.

Making genomics functional: deciphering the genetics of acute lung injury

Acute lung injury (ALI) is a common and frequently devastating illness characterized by acute hypoxemic respiratory failure, profound inflammation, and flooding of the alveoli. Despite recent advances in ALI care, the morbidity and mortality of ALI continues to be unacceptably high. ALI-inciting events (e.g., sepsis, trauma, aspiration, pneumonia) are quite common, yet only a fraction of patients develop the syndrome. This heterogeneity of patients presenting with ALI has sparked interest in identifying the role of genetic factors that contribute to ALI susceptibility and prognosis. Recent advances in high-throughput sequencing and expression technologies now provide the tools to perform large-scale genomic analyses in complex disorders such as ALI; gene expression profiling and pathway analysis provide further insight into previously described molecular pathways involved in the syndrome. In this article, we describe the use of genomewide association studies, ortholog in silico techniques, utility of consomic rat methods, and candidate gene approaches using expression profiling and pathway analyses. These methods have confirmed suspected ALI candidate genes (e.g., IL-6 and MIF), but more impressively have identified novel genes (e.g., GADD45alpha and PBEF) not previously suspected in ALI. The analysis of the molecular pathways (e.g., the cytoskeleton in vascular barrier regulation) has identified additional genes contributing to the development and severity of ALI (e.g., MLCK), thereby providing therapeutic targets in this devastating illness.

Integrating genomic and clinical medicine: searching for susceptibility genes in complex lung diseases

The integration of molecular, genomic, and clinical medicine in the post-genome era provides the promise of novel information on genetic variation and pathophysiologic cascades. The current challenge is to translate these discoveries rapidly into viable biomarkers that identify susceptible populations and into the development of precisely targeted therapies. In this article, we describe the application of comparative genomics, microarray platforms, genetic epidemiology, statistical genetics, and bioinformatic approaches within examples of complex pulmonary pathobiology. Our search for candidate genes, which are gene variations that drive susceptibility to and severity of enigmatic acute and chronic lung disorders, provides a logical framework to understand better the evolution of genomic medicine. The dissection of the genetic basis of complex diseases and the development of highly individualized therapies remain lofty but achievable goals.

Differential and cell-type specific regulation of responses to Toll-like receptor agonists by ISO-1

Macrophage migration inhibitory factor (MIF) plays vital roles in the regulation of responses to stimuli acting via Toll-like receptor (TLR)-4. Recently, a specific small molecule inhibitor of MIF (ISO-1) has been described. We investigated the effects of ISO-1 on TLR responses in primary human monocytes and monocyte-derived macrophages (MDM). In monocytes, ISO-1 caused marked suppression of TLR4-induced proinflammatory cytokine production, and to a lesser extent suppression of TLR2-induced responses. The lipopolysaccharide (LPS)-induced activation of cocultures of monocytes and endothelial cells was strongly inhibited by ISO-1. Suppression of monocyte TLR4 signalling by ISO-1 was associated with alterations in extracellular signal-related kinase (ERK)-1/2 activation status. Previously, regulation of TLR4 signalling by MIF has been noted to be through control of TLR4 expression, but we observed that the actions of ISO-1 were mediated without changes in cell surface TLR4 levels. In contrast, ISO-1 pretreatment did not inhibit responses of MDM to LPS. ISO-1 is a promising parent molecule which inhibits TLR-induced ERK activation and inflammatory cytokine production in monocytes, whose role may be complicated by cell-type specificity.

A role for macrophage migration inhibitory factor in the neonatal respiratory distress syndrome

Using a mouse model of neonatal respiratory distress syndrome (RDS), we demonstrate a central role for macrophage migration inhibitory factor (MIF) in lung maturation at the developmental stage when human neonates are most susceptible to RDS. We prematurely delivered mouse pups at embryonic day 18, during the early saccular stage of pulmonary development. Only 8% of the prematurely delivered pups genetically deficient in MIF survived 8 h vs 75% of wild-type controls (p<0.001). This phenotype was corrected when pups of all genotypes were bred from dams heterozygote for MIF deficiency. Local production of MIF in the lung increased at embryonic day 18, continued until full-term at embryonic day 19.5, and decreased in adulthood, thus coinciding with this developmental window. The lungs of pups genetically deficient in MIF were less mature upon histological evaluation, and demonstrated lower levels of vascular endothelial growth factor and corticosterone--two factors that promote fetal lung maturation. In vitro studies support a role for MIF in surfactant production by pulmonary epithelial cells. In a cohort of human neonates with RDS, higher intrapulmonary MIF levels were associated with a lower likelihood of developing bronchopulmonary dysplasia, a sequelae of RDS (p<0.03). This study demonstrates for the first time a role for MIF in lung maturation, and supports a protective role for MIF in newborn lung disease.

Macrophage migration inhibitory factor stimulates AMP-activated protein kinase in the ischaemic heart

Understanding cellular response to environmental stress has broad implications for human disease. AMP-activated protein kinase (AMPK) orchestrates the regulation of energy-generating and -consuming pathways, and protects the heart against ischaemic injury and apoptosis. A role for circulating hormones such as adiponectin and leptin in the activation of AMPK has received recent attention. Whether local autocrine and paracrine factors within target organs such as the heart modulate AMPK is unknown. Here we show that macrophage migration inhibitory factor (MIF), an upstream regulator of inflammation, is released in the ischaemic heart, where it stimulates AMPK activation through CD74, promotes glucose uptake and protects the heart during ischaemia-reperfusion injury. Germline deletion of the Mif gene impairs ischaemic AMPK signalling in the mouse heart. Human fibroblasts with a low-activity MIF promoter polymorphism have diminished MIF release and AMPK activation during hypoxia. Thus, MIF modulates the activation of the cardioprotective AMPK pathway during ischaemia, functionally linking inflammation and metabolism in the heart. We anticipate that genetic variation in MIF expression may impact on the response of the human heart to ischaemia by the AMPK pathway, and that diagnostic MIF genotyping might predict risk in patients with coronary artery disease.

Systemic fetal inflammation and reduced concentrations of macrophage migration inhibitory factor in tracheobronchial aspirate fluid of extremely premature infants

OBJECTIVE

Macrophage migration inhibitory factor is a proinflammatory mediator of innate immunity, enhances cell growth, and plays a role in preterm delivery. We speculated that funisitis, reflecting fetal systemic inflammation, would be associated with higher concentrations of macrophage migration inhibitory factor in airways of extremely premature infants.

STUDY DESIGN

We measured macrophage migration inhibitory factor by enzyme linked immunosorbent assay in tracheobronchial aspirate fluid of 35 ventilated infants less than 30 weeks' gestational age, throughout the first week of life. Three groups were distinguished histologically: chorioamnionitis, funisitis, and control.

RESULTS

Unexpectedly, funisitis was associated with significantly decreased macrophage migration inhibitory factor in tracheobronchial aspirate fluid on day 1 (P < .01) and levels remained lower than in the chorioamnionitis group thereafter. For the 35 patients in total, macrophage migration inhibitory factor steadily declined.

CONCLUSION

Decreased macrophage migration inhibitory factor concentrations in airways of extremely premature infants with systemic fetal inflammation early in life might predispose them to pulmonary infection and interfere with maturation of the lung, contributing to adverse pulmonary outcome.

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.

Serum macrophage migration inhibitory factor (MIF) levels after allogeneic hematopoietic stem cell transplantation

Macrophage migration inhibitory factor (MIF) may play an important role in the pathogenesis of acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), as MIF plays an important role to regulate the production of tumor necrosis factor-alpha (TNF-alpha), one of the inflammatory cytokines which induces and exacerbates aGVHD. We examined the association between serum MIF levels and aGVHD vs. chronic GVHD (cGVHD) in allo-SCT patients in this study. We found a significant increase in the peak serum MIF (14.46 ng +/- 1.47 ng/ml) at onset in patients that developed aGVHD (n = 23, P = 0.009). We also found that mean serum MIF levels in patients who developed extensive type cGVHD within 6 months (12.58 +/- 2.18 ng/ml, n = 13) were significantly higher than MIF levels before allo-HSCT (7.86 +/- 1.17 ng/ml, n = 19, P = 0.04). Therefore, we speculated that serum MIF levels increase during the active phase of both aGVHD and cGVHD.

The role of macrophage migration inhibitory factor in the cascade of events leading to reperfusion-induced inflammatory injury and lethality

Ischemia and reperfusion (I/R) injury is associated with a systemic inflammatory response, characterized by intense tumor necrosis factor (TNF)-alpha production and TNF-alpha-dependent tissue injury. Macrophage migration inhibitory factor (MIF) is a potent proinflammatory cytokine that may induce TNF-alpha release and play an important role in innate immune and inflammatory responses. The aim of this work was to assess whether MIF was involved the inflammatory cascade and injury that follows intestinal I/R. To this end, wild-type (WT) and MIF-deficient (MIF(-/-)) mice underwent 60 minutes of ischemia followed by 60 minutes of reperfusion, after which they were culled for the assessment of inflammatory parameters. I/R was accompanied by an increase in circulating levels of MIF and an increase of vascular permeability, hemorrhage, and production of TNF-alpha in the intestine and lungs. The latter parameters were markedly suppressed in reperfused MIF(-/-) mice, and this was associated with decreased lethality (80% in WT versus 20% in MIF(-/-) mice). Interestingly, the reperfusion-associated neutrophil accumulation in the intestine and lungs was similar in WT and MIF(-/-) mice. Leukocytes isolated from lungs of MIF(-/-) mice were less activated, as assessed by their response to zymosan in a luminol-enhanced chemiluminescence assay. In conclusion, our results suggest that MIF plays an important role in the cascade of events leading to TNF-alpha production and reperfusion-induced tissue injury and lethality in mice.

Abrogation of macrophage migration inhibitory factor decreases West Nile virus lethality by limiting viral neuroinvasion

The flavivirus West Nile virus (WNV) is an emerging pathogen that causes life-threatening encephalitis in susceptible individuals. We investigated the role of the proinflammatory cytokine macrophage migration inhibitory factor (MIF), which is an upstream mediator of innate immunity, in WNV immunopathogenesis. We found that patients suffering from acute WNV infection presented with increased MIF levels in plasma and in cerebrospinal fluid. MIF expression also was induced in WNV-infected mice. Remarkably, abrogation of MIF action by 3 distinct approaches (antibody blockade, small molecule pharmacologic inhibition, and genetic deletion) rendered mice more resistant to WNV lethality. Mif(-/-) mice showed a reduced viral load and inflammatory response in the brain when compared with wild-type mice. Our results also indicate that MIF favors viral neuroinvasion by compromising the integrity of the blood-brain barrier. In conclusion, the data obtained from this study provide direct evidence for the involvement of MIF in viral pathogenesis and suggest that pharmacotherapeutic approaches targeting MIF may hold promise for the treatment of WNV encephalitis.

Macrophage migration inhibitory factor polymorphisms do not predict therapeutic response to glucocorticoids or to tumour necrosis factor alpha-neutralising treatments in rheumatoid arthritis

BACKGROUND

Macrophage migration inhibitory factor (MIF) is an inflammatory mediator associated with RA severity. In various diseases, MIF polymorphisms are associated with clinical response glucocorticoid (GC) treatment. It is unclear whether MIF polymorphisms determine GC response in rheumatoid arthritis (RA) and to other RA treatments. Therefore, the question of whether two functional variants in MIF are associated with the response to tumour necrosis factor (TNF)alpha-neutralising and GC treatments in RA was investigated.

METHODS

Data from two cohorts of an RA registry were used. For patients who started with TNFalpha-neutralising (infliximab) or GC treatment, courses with a duration of at least 3 months were included and response to TNFalpha blockers or GC was calculated according to the European League Against Rheumatism response criteria. MIF -173G-->C genotyping was achieved using an assay-on-demand allelic discrimination assay, and alleles of the CATT repeat element were identified using a fluorescently labelled PCR primer and capillary electrophoresis. Logistic-regression modelling was used for the statistical analysis.

RESULTS

In total, 192 courses of oral prednisone or methylprednisolone injections in 98 patients with RA and 90 patients with RA who were on TNFalpha-neutralising treatments were documented. In all, 27% of the patients with RA were found to be heterozygous for seven CATT repeats (CATT(7)) and 31% were heterozygous for -173C. Respectively, 4% and 6% of the patients with RA were homozygous for the MIF CATT(7) repeat or the MIF -173C allele. Carrier status and homozygosity for CATT(7 )repeat and the MIF -173C allele were not associated with response to GC (odds ratios (ORs) close to 1) or to TNFalpha-neutralising treatment (ORs close to 2).

CONCLUSION

The MIF-CATT(7) repeat and the MIF-173G-->C functional variant are not strongly associated with a decreased clinical response to TNFalpha-neutralising or GC treatment in RA.

Lung-derived macrophage migration inhibitory factor in sepsis induces cardio-circulatory depression

BACKGROUND

Acute lung injury is common during sepsis. Whereas gaseous exchange often can be supported adequately, death results frequently from cardio-circulatory depression, the mechanisms of which remain unclear. The aim of this study was to determine whether cardio-circulatory dysfunction during sepsis results from release of macrophage migration inhibitory factor (MIF) by the lung.

METHODS

Polymicrobial sepsis was induced by cecal ligation and puncture (CLP) in adult Sprague-Dawley rats. Macrophage MIF was measured in the plasma sampled from the right ventricle (pre-lung) and left atrium (post-lung).

RESULTS

The concentration of macrophage MIF in each of the post-lung samples was higher than in the corresponding pre-lung sample at 6 h (p = 0.015; paired t-test), 20 h (p = 0.008), and 30 h (p = 0.026) after the induction of sepsis. Next, rats that underwent CLP were treated with either saline (control) or our specific MIF inhibitor, (S, R )-3-(4-hydroxyphenyl)-4,5-dehydro-5-isoxazole acetic acid methyl ester (ISO-1). Echocardiography revealed that ISO-1 significantly improved the left ventricular end-diastolic volume index (p = 0.02), stroke volume index (p = 0.01), and cardiac index (p = 0.02) at 30 h after the induction of sepsis.

CONCLUSIONS

The lung appears to release significant amounts of macrophage MIF into the systemic circulation during late sepsis. Inhibition of MIF in a clinically relevant time frame blocked polymicrobial peritonitis-induced cardio-circulatory dysfunction. Inhibition of MIF may be a useful strategy to prevent cardio-circulatory deterioration associated with late sepsis.

Macrophage migration inhibitory factor does not modulate co-activation of androgen receptor by Jab1/CSN5

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory immune modulator that plays an important role in the regulation of innate and adaptive immune responses. MIF signaling involves CD74/CD44 membrane receptor complexes, the chemokine receptors CXCR2 and 4 as well as uptake by non-receptor mediated endocytosis. Endocytosed or endogenous MIF interacts with Jun activation domain-binding protein 1 (Jab1), originally described as transcriptional co-activator for the transcription factor AP-1, that is also known as subunit 5 of the COP9 signalosome (CSN5). Since Jab1/CSN5 also functions as a co-activator for a number of steroid hormone receptors (SHRs), it had been speculated that MIF could modulate Jab1/CSN5-SHR interactions. Here we show (i) that fluorescently labeled MIF is internalized by NIH 3T3 cells within minutes, (ii) compromises the induction of phospho-c-Jun levels by TNFalpha and PMA and, hence, is biologically active, but (iii) is not able to interfere with co-activation by Jab1/CSN5 of the androgen receptor.

Increased serum levels of macrophage migration inhibitory factor in patients with Kawasaki disease

OBJECTIVE

To determine whether serum levels of macrophage migration inhibitory factor (MIF) increase in patients with Kawasaki disease (KD) and also correlate with other inflammatory indices.

METHODS

Serum samples from 10 patients with KD, 15 normal healthy subjects, and seven febrile control subjects were assayed for MIF by enzyme-linked immunosorbent assay (ELISA).

RESULTS

There was a significant increase in the serum levels of MIF in the acute stage of KD [113.06 (range 20.6-157.36) ng/mL] compared with those in the subacute stage [28.11 (8.57-143.48) ng/mL, p<0.01], normal controls [12.95 (8.40-18.67) ng/mL, p<0.001], and febrile controls [36.58 (21.31-59.67) ng/mL, p = 0.01]. The increase in MIF correlated with an increase in interleukin-6 (IL-6) (r = 0.52, p = 0.047).

CONCLUSION

MIF may be a useful marker in the acute stage of KD and may provide important clues to the pathogenesis of this disease.

Acute alcohol intake impairs lung inflammation by changing pro- and anti-inflammatory mediator balance

Previous studies have shown that alcohol (ethanol [EtOH]) intoxication impairs lung immunity by affecting cytokines pivotal to the inflammatory process. The objective of this study was to test the hypothesis that acute alcohol intoxication impairs lung innate immunity by downregulating the expression of proinflammatory mediators while simultaneously upregulating anti-inflammatory mediators. EtOH was administered to the mice 0.5h prior to an intratracheal injection of Escherichia coli lipopolysaccharide (LPS). The animals were killed either 4 or 24h after LPS to recover plasma, lungs, and bronchoalveolar lavage fluid. Lung inflammatory cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1beta), IL-6, macrophage inhibitory factor (MIF), IL-10, TGF-beta, and receptors for TNF-alpha, IL-1beta, IL-6, and TGF-beta as well as glycoprotein (gp)130 and corticosterone (CS) levels were evaluated at mRNA and protein level. While the mRNA expression and the soluble TNF-Rp55 levels were significantly upregulated by EtOH, LPS-induced TNF-alpha activity, TNF-Rp55 mRNA expression, and soluble TNF-Rp55 levels were significantly suppressed. The LPS-induced expression of IL-1beta, IL-6, MIF, gp130, and receptors IL-1RI, IL-1RII, and IL-6Ralpha were also significantly impaired by EtOH. EtOH increased significantly the basal IL-10 activity at 3h, which continued to remain elevated even at 24h. The EtOH effect on IL-10 activity persisted even in LPS-challenged mice. EtOH and LPS augmented lung CS levels independently of each other. EtOH suppressed upregulation of TGF-beta1 mRNA expression by LPS and blocked completely LPS-induced TGF-beta1 secretion. In conclusion, the data suggest that the suppression of acute lung inflammation by EtOH intoxication is largely due to impairment by EtOH of proinflammatory cytokine signaling at the levels of cytokine expression and secretion as well as receptor expression and soluble receptor activity. The augmentation by EtOH of anti-inflammatory mediators' secretion most likely shifts the cytokine balance in the anti-inflammatory direction.

Macrophage migration inhibitory factor: gene polymorphisms and susceptibility to inflammatory diseases

The cytokine macrophage migration inhibitory factor (MIF) is a constitutive element of the host antimicrobial defenses and stress response that promotes proinflammatory function of the innate and acquired immune systems. MIF plays an important role in the pathogenesis of acute and chronic inflammatory or autoimmune disorders, such as sepsis, acute respiratory distress syndrome, asthma, rheumatoid arthritis, and inflammatory bowel diseases. Polymorphisms of the human MIF gene (that is, guanine-to-cytosine transition at position -173 or CATT-tetranucleotide repeat at position -794) have been associated with increased susceptibility to or severity of juvenile idiopathic and adult rheumatoid arthritis, ulcerative colitis, atopy, or sarcoidosis. Whether these MIF polymorphisms affect the susceptibility to and outcome of sepsis has not yet been examined. Analyses of MIF genotypes in patients with sepsis may help to classify patients into risk categories and to identify those patients who may benefit from anti-MIF therapeutic strategies.

Macrophage migration inhibitory factor in acute lung injury: expression, biomarker, and associations

The macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine central to the response to endotoxemia, is a putative biomarker in acute lung injury (ALI). To explore MIF as a molecular target and candidate gene in ALI, the MIF gene and protein expression were examined in murine and canine models of ALI (high tidal volume mechanical ventilation, endotoxin exposure) and in patients with either sepsis or sepsis-induced ALI. MIF gene expression and protein levels were significantly increased in each ALI model, with serum MIF levels significantly higher in patients with either sepsis or ALI compared with healthy controls (African- and European-descent). The association of 8 MIF gene polymorphisms (single-nucleotide polymorphisms (SNPs)) (within a 9.7-kb interval on chromosome 22q11.23) with the development of sepsis and ALI in European-descent and African-descent populations was studied next. Genotyping in 506 DNA samples (sepsis patients, sepsis-associated ALI patients, and healthy controls) revealed haplotypes located in the 3' end of the MIF gene, but not individual SNPs, associated with sepsis and ALI in both populations. These data, generated via functional genomic and genetic approaches, suggest that MIF is a relevant molecular target in ALI.

Structural and functional characterization of a secreted hookworm Macrophage Migration Inhibitory Factor (MIF) that interacts with the human MIF receptor CD74

Hookworms, parasitic nematodes that infect nearly one billion people worldwide, are a major cause of anemia and malnutrition. We hypothesize that hookworms actively manipulate the host immune response through the production of specific molecules designed to facilitate infection by larval stages and adult worm survival within the intestine. A full-length cDNA encoding a secreted orthologue of the human cytokine, Macrophage Migration Inhibitory Factor (MIF) has been cloned from the hookworm Ancylostoma ceylanicum. Elucidation of the three-dimensional crystal structure of recombinant AceMIF (rAceMIF) revealed an overall structural homology with significant differences in the tautomerase sites of the human and hookworm proteins. The relative bioactivities of human and hookworm MIF proteins were compared using in vitro assays of tautomerase activity, macrophage migration, and binding to MIF receptor CD74. The activity of rAceMIF was not inhibited by the ligand ISO-1, which was previously determined to be an inhibitor of the catalytic site of human MIF. These data define unique immunological, structural, and functional characteristics of AceMIF, thereby establishing the potential for selectively inhibiting the hookworm cytokine as a means of reducing parasite survival and disease pathogenesis.

Macrophage migration inhibitory factor is essential for allergic asthma but not for Th2 differentiation

Macrophage migration inhibitory factor (MIF) is increased in asthmatic patients and plays a critical role in the pathogenesis of asthma. We show here that mice lacking MIF failed to develop airway hyper-responsiveness (AHR), tissue eosinophilia, and mucus metaplasia. Analysis of the bronchoalveolar fluids revealed a substantial reduction of IL-13, eotaxin and cysteinyl-leukotrienes. The lack of these cardinal features of asthma in MIF(-/-) mice occurs regardless of high concentrations of IL-4 in the lung and OVA-specific IgE in the serum. Antigen-specific lymphocyte proliferation and IL-13 production were similarly increased in the draining lymph nodes of OVA-immunized and challenged MIF(-/-) mice compared to WT, but were reduced in the spleen of MIF(-/-), thus indicating differential roles of MIF in these compartments. Stimulation of naive CD4(+) cells with anti-CD3 antibody demonstrated that MIF(-/-) cells produced increased amounts of IFN-gamma and IL-4 compared to WT CD4(+) cells. Finally, treatment of sensitized BALB/c mice with neutralizing anti-MIF antibody abrogated the development of ARH and airway inflammation without affecting the production of Th2 cytokines or IgE. The present study demonstrates that MIF is required for allergic inflammation, adding important elements to our knowledge of asthma pathogenesis and suggesting that neutralization of MIF might be of therapeutic value in asthma.

Macrophage migration inhibitory factor: a probable link between inflammation and cancer

The pleiotropic effects of macrophage migration inhibitory factor (MIF) place it in a central position in the immunopathogenesis of many diseases. Here we discuss the current understanding of MIF's role and highlight it as a potential link between inflammatory activation and malignant progression.

INCREASES IN SERUM MACROPHAGE MIGRATION INHIBITORY FACTOR IN PATIENTS WITH SEVERE SEPSIS PREDICT EARLY MORTALITY

This prospective study aimed to delineate the association between the serum levels of macrophage migration inhibitory factor (MIF) and the risks of early mortality in 112 patients who presented with clinically severe sepsis. Previous studies showed that elevated serum MIF levels on the first day are associated with an increased risk of 28-day mortality. Nonsurvivors may be the sickest population on arrival. Not all patients with severe sepsis follow the same clinical pathway, however, and the sequential change in MIF might be an important predictor of mortality. We hypothesized that, for septic patients, in addition to serum MIF levels on day 1, the percentage of change in MIF between days 1 and 2 after arriving in the emergency department predicts the probability of early mortality. Serum MIF levels were measured on days 1 (emergency department arrival) and 2 (24 h after arrival). Patients with a high percentage of increase between MIF levels on days 1 and 2 had higher 3-day (odds ratio, 1.8; 95% confidence interval, 1.2-2.6; P = 0.003) and 7-day mortalities (odds ratio, 1.4; 95% confidence interval, 1.0-1.9; P = 0.03) after adjusting for age and day-1 serum MIF levels. In conclusion, an increase in serum MIF from the first to second day of admission in patients with severe sepsis indicates a higher risk of early mortality; therefore, these patients need more aggressive therapeutic intervention.

Downregulation of migration inhibitory factor is critical for estrogen-mediated attenuation of lung tissue damage following trauma-hemorrhage

Although studies have shown that 17β-estradiol (E2) prevents neutrophil infiltration and organ damage following trauma-hemorrhage, the mechanism by which E2inhibits neutrophil transmigration remains unknown. Macrophage migration inhibitory factor (MIF) is thought to play a central role in exacerbation of inflammation and is associated with lung injury. MIF regulates the inflammatory response through modulation of Toll-like receptor 4 (TLR4). Activation of TLR4 results in the release of proinflammatory cytokines and chemokines, which induce neutrophil infiltration and subsequent tissue damage. We hypothesized that E2mediates its salutary effects in the lung following trauma-hemorrhage via negative regulation of MIF and modulation of TLR4 and cytokine-induced chemotaxis. C3H/HeOuJ mice were subjected to trauma-hemorrhage (mean blood pressure 35 ± 5 mmHg for ∼90 min, then resuscitation) or sham operation. Mice received vehicle, E2, or E2in combination with recombinant mouse MIF protein (rMIF). Trauma-hemorrhage increased lung MIF and TLR4 protein levels as well as lung and systemic levels of cytokines/chemokines. Treatment of animals with E2following trauma-hemorrhage prevented these changes. However, administration of rMIF protein with E2abolished the E2-mediated decrease in lung TLR4 levels, lung and plasma levels of IL-6, TNF-α, monocyte chemoattractant protein-1, and keratinocyte-derived chemokine (KC). Administration of rMIF protein also prevented E2-mediated reduction in neutrophil influx and tissue damage in the lungs following trauma-hemorrhage. These results suggest that the protective effects of E2on lung injury following trauma-hemorrhage are mediated via downregulation of lung MIF and TLR4-induced cytokine/chemokine production.

MIF is a noncognate ligand of CXC chemokine receptors in inflammatory and atherogenic cell recruitment

The cytokine macrophage migration inhibitory factor (MIF) plays a critical role in inflammatory diseases and atherogenesis. We identify the chemokine receptors CXCR2 and CXCR4 as functional receptors for MIF. MIF triggered G(alphai)- and integrin-dependent arrest and chemotaxis of monocytes and T cells, rapid integrin activation and calcium influx through CXCR2 or CXCR4. MIF competed with cognate ligands for CXCR4 and CXCR2 binding, and directly bound to CXCR2. CXCR2 and CD74 formed a receptor complex, and monocyte arrest elicited by MIF in inflamed or atherosclerotic arteries involved both CXCR2 and CD74. In vivo, Mif deficiency impaired monocyte adhesion to the arterial wall in atherosclerosis-prone mice, and MIF-induced leukocyte recruitment required Il8rb (which encodes Cxcr2). Blockade of Mif but not of canonical ligands of Cxcr2 or Cxcr4 in mice with advanced atherosclerosis led to plaque regression and reduced monocyte and T-cell content in plaques. By activating both CXCR2 and CXCR4, MIF displays chemokine-like functions and acts as a major regulator of inflammatory cell recruitment and atherogenesis. Targeting MIF in individuals with manifest atherosclerosis can potentially be used to treat this condition.

Macrophage migration inhibitory factor induces MMP-9 expression in macrophages via the MEK-ERK MAP kinase pathway

We have shown previously that macrophage migration inhibitory factor (MIF) may play a role in the destabilization of atherosclerotic plaques by activating matrix metalloproteinase protein-9 (MMP-9). The aim of this study is to investigate the signaling mechanism by which MIF induces MMP-9 expression and activation in a murine macrophage line (RAW264.7). MIF was able to activate extracellular signal-regulated kinase 1/2 (ERK1/2), to a less extent JNK, but not p38 mitogen-activated protein (MAP), MAP kinase to induce MMP9 mRNA and protein expression in RAW264.7 murine macrophages. This was confirmed by the findings that addition of an ERK MAP kinase inhibitor (PD98059) but not a p38 inhibitor (SB203589) abolished MIF-induced MMP-9 expression and activation, whereas addition of a JNK inhibitor (SP600125) produced a partially inhibitory effect. The functional role of mitogen-activated protein kinase kinase (MEK)-ERK MAP kinase in MIF-induced MMP-9 expression was further confirmed by overexpressing dominant negative MEK (DN-MEK) and DN-ERK MAP kinases. Interestingly, constitutive expression of a wild-type (WT)-MEK alone was also capable of inducing a low, but significant MMP-9 mRNA and protein expression but did not cause a further increase in MMP-9 in response to MIF. MIF activates the MEK-ERK MAP kinase pathway to induce MMP-9 expression by murine macrophages. Activation of this pathway is necessary for MMP-9 expression and activation in response to MIF stimulation.

The macrophage migration inhibitory factor-glucocorticoid dyad: regulation of inflammation and immunity

The cytokine macrophage migration inhibitory factor (MIF) occupies a unique position in physiology by its ability to directly regulate the immunosuppressive actions of glucocorticoids. We review herein the interactions between MIF and glucocorticoids within the immune system and discuss the relevance of the MIF-glucocorticoid regulatory dyad in physiology and immunopathology. Therapeutic antagonism of MIF may be an effective approach for steroid-sparing therapies in patients with refractory autoimmune or inflammatory diseases.

Serum macrophage migration inhibitory factor is an early marker of pancreatic necrosis in acute pancreatitis

OBJECTIVE

To determine if 24-hour blood concentrations of macrophage migration inhibitory factor (MIF), soluble CD14, and CD163 receptors could predict complications associated with acute pancreatitis (AP).

SUMMARY BACKGROUND DATA

Soluble receptor proteins derived from the macrophage-monocyte lineage potentiate the inflammatory cytokine response early in AP. Understanding the temporal expression of these molecules could afford better measures for therapeutic intervention.

METHODS

Patients with AP (amylase >5 times normal) were recruited within 24-hour of onset of pain. Peripheral blood was analyzed for MIF, sCD163, and sCD14 levels and levels correlated with CRP, APACHE-II score, and clinical disease severity (Atlanta criteria); subclassified as multiorgan dysfunction (MOF), pancreatic necrosis (PN >30% on contrast CT), and death.

RESULTS

In total, 64 patients with AP (severe, 19: 8 had MOF alone, 7 both PN and MOF, 2 PN without MOF, and 2 single-organ failures with local septic complications) were recruited. Both sCD14 and MIF concentrations were elevated in patients with severe attacks (P = 0.004 and P < 0.001 respectively), and patients who developed MOF (P = 0.004 and P < 0.001). However, only serum MIF was significantly raised in patients who subsequently developed PN (median, 92.5 ng/mL; IQR, 26-181 vs. 31.1 ng/mL; IQR, 5-82, P < 0.001), independently of MOF (P = 0.01). Multivariate analysis demonstrated serum MIF as an independent predictor of PN (P = 0.01; OR = 2.73; 95% CI, 2.72-2.74).

CONCLUSION

The prognostic utility of 24-hour plasma MIF concentration in predicting PN has major clinical and healthcare resource implications. Its mechanistic pathway may afford novel therapeutic interventions in clinical disease by using blocking agents to ameliorate the systemic manifestations of AP.

Macrophage migration inhibitory factor induces macrophage recruitment via CC chemokine ligand 2

Macrophage migration inhibitory factor (MIF) was originally identified for its ability to inhibit the random migration of macrophages in vitro. MIF is now recognized as an important mediator in a range of inflammatory disorders. We recently observed that the absence of MIF is associated with a reduction in leukocyte-endothelial cell interactions induced by a range of inflammatory mediators, suggesting that one mechanism whereby MIF acts during inflammatory responses is by promoting leukocyte recruitment. However, it is unknown whether MIF is capable of inducing leukocyte recruitment independently of additional inflammatory stimuli. In this study, we report that MIF is capable of inducing leukocyte adhesion and transmigration in postcapillary venules in vivo. Moreover, leukocytes recruited in response to MIF were predominantly CD68(+) cells of the monocyte/macrophage lineage. Abs against the monocyte-selective chemokine CCL2 (JE/MCP-1) and its receptor CCR2, but not CCL3 and CXCL2, significantly inhibited MIF-induced monocyte adhesion and transmigration. CCL2(-/-) mice displayed a similar reduction in MIF-induced recruitment indicating a critical role of CCL2 in the MIF-induced response. This hypothesis was supported by findings that MIF induced CCL2 release from primary microvascular endothelial cells. These data demonstrate a previously unrecognized function of this pleiotropic cytokine: induction of monocyte migration into tissues. This function may be critical to the ability of MIF to promote diseases such as atherosclerosis and rheumatoid arthritis, in which macrophages are key participants.

Macrophage migration inhibitory factor (MIF) -173G/C promoter polymorphism influences upper gastrointestinal tract involvement and disease activity in patients with Crohn's disease

BACKGROUND

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with increased expression in inflammatory bowel disease. The aim of the study was to analyze the role of the MIF -173G/C single nucleotide polymorphism in Crohn's disease (CD).

METHODS

Using restriction fragment length polymorphism analysis, genomic DNA of 198 patients with CD and 159 unrelated controls was analyzed for the -173G/C SNP in the MIF promoter region. Colonic MIF mRNA expression was measured by quantitative polymerase chain reaction (PCR), serum MIF levels by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Thirty-six of the 146 G/G wildtype carriers (24.7%) but only 3 of the 45 G/C heterozygotes (6.7%) and only 1 of the C/C homozygotes (14.3%) were diagnosed with upper gastrointestinal tract involvement (P = 0.009, odds ratio [OR] = 0.22, 95% confidence interval [CI], 0.06-0.75 for wildtype versus hetero- and homozygous carriers). This result was confirmed in a second prospective study, in which all patients diagnosed with upper gastrointestinal involvement (n = 13) were G/G wildtype carriers (P = 0.01 versus controls). All patients (n = 12; 100%) with a Crohn's disease activity index (CDAI) > 300 were G/G wildtype carriers compared to only 65.6% wildtype carriers in the group with a CDAI < 150 (P = 0.016). MIF is expressed in the colonic mucosa of CD patients and intestinal epithelial cells but its mRNA expression does not correlate with the degree of inflammation and is not upregulated by proinflammatory cytokines. In CD, MIF serum levels are not influenced by the MIF -173G/C polymorphism.

CONCLUSIONS

The MIF -173G/C polymorphism appears to be a factor contributing to a particular CD phenotype characterized by protection against upper gastrointestinal tract involvement and severe disease activity.

Pathophysiology of pulmonary complications of acute pancreatitis

Acute pancreatitis in its severe form is complicated by multiple organ system dysfunction, most importantly by pulmonary complications which include hypoxia, acute respiratory distress syndrome, atelectasis, and pleural effusion. The pathogenesis of some of the above complications is attributed to the production of noxious cytokines. Clinically significant is the early onset of pleural effusion, which heralds a poor outcome of acute pancreatitis. The role of circulating trypsin, phospholipase A2, platelet activating factor, release of free fatty acids, chemoattractants such as tumor necrosis factor (TNF)-alpha, interleukin (IL)-1, IL-6, IL-8, fMet-leu-phe (a bacterial wall product), nitric oxide, substance P, and macrophage inhibitor factor is currently studied. The hope is that future management of acute pancreatitis with a better understanding of the pathogenesis of lung injury will be directed against the production of noxious cytokines.

Cutting Edge: Deficiency of Macrophage Migration Inhibitory Factor Impairs Murine Airway Allergic Responses

Increased levels of macrophage migration inhibitory factor (MIF) in serum, sputum, and bronchioalveolar lavage fluid (BALF) from asthmatic patients and time/dose-dependent expression of MIF in eosinophils in response to phorbol myristate acetate suggest the participation of MIF in airway inflammation. In this study, we examined inflammation in OVA-sensitized mouse lungs in wild-type and MIF-deficient mice (MIF(-/-)). We report increased MIF in the lung and BALF of sensitized wild-type mice. MIF(-/-) mice demonstrated significant reductions in serum IgE and alveolar inflammatory cell recruitment. Reduced Th1/Th2 cytokines and chemokines also were detected in serum or BALF from MIF(-/-) mice. Importantly, alveolar macrophages and mast cells, but not dendritic cells or splenocytes, from MIF(-/-) mice demonstrated impaired CD4+ T cell activation, and the reconstitution of wild-type mast cells in MIF(-/-) mice restored the phenotype of OVA-induced airway inflammation, revealing a novel and essential role of mast cell-derived MIF in experimentally induced airway allergic diseases.

KL4-surfactant prevents hyperoxic and LPS-induced lung injury in mice

KL(4)-surfactant contains the novel KL(4) peptide, sinapultide, which mimics properties of the hydrophobic pulmonary surfactant protein SP-B, in a phospholipid formulation and may be lung protective in experimental acute respiratory distress syndrome/acute lung injury. Our objective was to determine the protective role of airway delivery of KL(4)-surfactant in murine models of hyperoxic and lipopolysaccharide (LPS)-induced lung injury and further explore the mechanisms of protection. For the hyperoxic injury model, mice exposed to 80% O(2) for 6 days received an intranasal bolus of vehicle, beractant, or KL(4)-surfactant on days 3, 4, 5, and 6 of the exposure, and lungs were evaluated on day 7. Mice in the LPS-induced lung injury model received an intratracheal bolus of LPS followed by an intranasal bolus of KL(4)-surfactant or control at 1, 3, and 19 hr post-LPS challenge, and lungs were evaluated after 24 hr. To explore the mechanisms of protection, in vitro assays were performed with human and murine endothelial cell monolayers, and polymorphonuclear leukocyte (PMN) transmigration in the presence or absence of KL(4)-surfactant or lipid controls was evaluated. Based on morphology, histopathology, white blood cell count, percentage of PMNs, and protein concentration in bronchoalveolar lavage fluid, our data showed KL(4)-surfactant, unlike vehicle or beractant, blocked neutrophil influx into alveoli and suppressed lung injury. Furthermore, in vitro assays showed KL(4)-surfactant decreased neutrophil transmigration at the endothelial cell level. KL(4)-surfactant decreased inflammation and lung permeability compared with controls in both mouse models of lung injury. Evidence suggests the anti-inflammatory mechanism of the KL(4)-peptide is through inhibition of PMN transmigration through the endothelium.

Resistance to experimental colitis depends on cytoprotective heat shock proteins in macrophage migration inhibitory factor null mice

Macrophage migration inhibitory factor plays an important role in inflammatory diseases. We investigated the role of macrophage migration inhibitory factor (MIF) in the development of dextran sulfate sodium (DSS)-induced colitis using MIF null ((-/-)) mice. MIF(-/-) mice given 3% DSS showed no clinical and histological feature of colitis in contrast to wild-type (WT) mice. Lack of MIF suppressed the up-regulation of TNF-alpha and IFN-gamma as Th1-derived cytokines, and increased the level of IL-4 as Th2-derived cytokine in the colon tissues. Moreover, we found that the expressions of heat shock protein (HSP)40 and HSP70 were markedly up-regulated in the colon of MIF(-/-) mice in response to DSS compared with WT mice. Additionally, quercetin, an inhibitor of HSP synthesis, inhibited the up-regulation of HSP40 and 70 expressions and developed DSS-induced colitis in MIF(-/-) mice. Our findings in this study provide more information in the role of MIF in colitis.

Respuesta inflamatoria y apoptosis en la lesión pulmonar aguda

One of the principal mechanisms of pulmonary injury in acute respiratory distress is due to the effects of the precipitated inflammatory response. The damage produced to the alveolar epithelium and underlying endothelium depends on the sequestration and activation of inflammatory cells, which in turn exert their actions through mediators. On the other hand, apoptosis is a mechanism responsible for epithelial damage and regulation of inflammation. Response of the lung tissue subjected to mechanical ventilation stimulus is added to the previous mechanisms. All these processes flow into a series of common pathways of cellular activation. Knowledge of these mechanisms could serve to identify which patients would benefit from a specific treatment before applying therapies that act indiscriminately in the inflammatory response.

Macrophage migration inhibitory factor in zinc-allergic systemic contact dermatitis

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine whose expression has been found to be critical to the generation of the antigen-specific immune response. Recent studies suggested that MIF plays a role in the initiation and maintenance of allergic disease. The aim of this study was to investigate whether MIF is involved in the pathogenesis of zinc-allergic systemic contact dermatitis. A 49-year-old Japanese woman developed facial edema, blepharedema and pruritic edematous erythema with papules over the entire body. Based of the results of a metal patch test, drug lymphocyte stimulating test and drug challenge test, diagnosis of zinc-allergic systemic contact dermatitis was made. Serum MIF and TNF-alpha levels of the patient, 20 healthy controls and other 6 patients who showed positive reaction to metal patch test were measured by an ELISA. Moreover we examined MIF production of peripheral blood mononuclear cells (PBMCs) from our patient, 3 healthy controls and other 2 patients who showed positive reaction to metal patch test at various metal concentrations. The patient's serum showed high MIF and TNF-alpha levels compared to healthy controls and other metal allergy patients. Furthermore, zinc stimulation of patient's PBMC showed higher MIF and TNF-alpha secretion compared with healthy subjects. The MIF content of 2 patients with other metal allergy was not significantly increased after metal stimulation. Our data suggest that zinc in the peripheral blood of zinc-allergic patients induce PBMCs to produce increased MIF levels, which could lead to systemic contact dermatitis.

Gastric epithelial expression of macrophage migration inhibitory factor is not altered by Helicobacter pylori infection in humans

BACKGROUND

Recent reports have shown an upregulation of macrophage migration inhibitory factor (MIF) during gastric ulcer development in a rat model and elevated counts of MIF-positive cells in biopsies from Helicobacter pylori-infected patients. H. pylori infection is a proven cofactor in humans causing gastritis and gastric ulcers. The aim of this study was to characterize MIF expression in human gastric epithelial cells in response to H. pylori.

METHODS

MIF mRNA and MIF protein expression was detected in human gastric epithelial cell lines after stimulation with proinflammatory cytokines or infection with H. pylori (cagA+/vacA+) using real-time reverse transcriptase-polymerase and enzyme-linked immunosorbent assay. Interleukin-8 secretion was measured as positive control. MIF mRNA and MIF protein expression was assessed in H. pylori-positive and -negative human gastric biopsy samples.

RESULTS

While interleukin-8 mRNA expression and interleukin-8 secretion were upregulated in gastric epithelial cells in vitro after H. pylori infection, no changes in MIF mRNA expression and MIF secretion could be detected. We found no significant differences in MIF expression in total RNA extracted from gastric biopsy tissue when comparing H. pylori-positive to control patients. Likewise, MIF protein expression in gastric epithelium was unaffected by H. pylori infection as compared to uninfected tissue.

CONCLUSIONS

While an increased MIF expression and positive effects of MIF blockade in ulcer healing have been shown in a rodent model and elevated numbers of MIF-positive cells have been found in H. pylori-infected human tissue, we herein could not confirm any differences in human gastric epithelial MIF expression and secretion after H. pylori infection in vitro and in vivo.

Dual regulation of macrophage migration inhibitory factor (MIF) expression in hypoxia by CREB and HIF-1

Macrophage migration inhibitory factor (MIF) is a well-described pro-inflammatory mediator that has also been implicated in the process of oncogenic transformation and tumor progression. However, despite the compelling evidence that MIF is overexpressed in, and contributes to, the pathology of inflammatory and malignant diseases the mechanisms that contribute to exaggerated expression of MIF have been poorly described. Here we show that hypoxia, and specifically HIF-1alpha, is a potent and rapid inducer of MIF expression. In addition, we demonstrate that hypoxia-induced MIF expression is dependent upon a HRE in the 5'UTR of the MIF gene but is further modulated by CREB expression. We propose a model where hypoxia-induced MIF expression is driven by HIF-1 but amplified by hypoxia-induced degradation of CREB. Given the importance of MIF in inflammatory and malignant diseases these data reveal a HIF-1-mediated pathway as a potential therapeutic target for suppression of MIF expression in hypoxic tissues.

Macrophage migration inhibitory factor has a proinflammatory activity via the p38 pathway in glucocorticoid-resistant ulcerative colitis

Macrophage migration inhibitory factor (MIF) is a cytokine that has potent anti-steroid effects and might be implicated in the pathogenesis of Ulecrative colitis (UC). We defined the functional role of MIF in the glucocorticoid (GC)-resistant inflammatory response in UC. Twenty-four colonic samples were obtained from GC responsive cases, GC refractory cases, Crohn's disease and controls. LPMC were isolated from surgical specimens. MIF was strongly expressed at mRNA levels in refractory cases rather than responsive cases with UC and controls. IL-8 production from LPMC was significantly reduced by GC addition in responsive cases but not in refractory cases. In refractory cases, anti-MIF Ab ameliorated GC-resistant IL-8 production and p38-MAPK activity of LPMC. In addition, p38-MAPK antagonist SB230580 also ameliorated GC-resistant IL-8 production. These results suggest that MIF has an additional proinflammatory activity through the p38-MAPK pathway in GC-resistant UC.

Effect of macrophage migration inhibitory factor (MIF) on acute graft-versus-host disease in a murine model of allogeneic stem cell transplantation

Macrophage migration inhibitory factor (MIF) may play an important role in the pathogenesis of acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic stem cell transplantation (HSCT). We examined whether MIF has an influence on the development of aGVHD and survival using BALB/c-based MIF knock-out (MIF KO) mice. Although MIF expression was observed in lymphocytes that had infiltrated the liver during aGVHD in both wild-type (WT) and MIF KO mice that received bone marrow cells (BM) and spleen cells (SP) from C57BL/6N mice, no significant difference was found in severity of aGVHD or survival rate between the two groups of mice. However, MIF level had decreased at 1 week after HSCT when MIF KO mice were used as the recipients. In the experiment using MIF KO mice as the donors, the recipient mice transplanted with BM and SP from MIF KO mice had significantly lower aGVHD scores on days 14, 21, and 35 than those in the recipient mice transplanted with BM and SP from WT-BALB/c mice. Histopathological findings supported these observations, showing that the bile ducts and lobules in the liver were destroyed by infiltrating MIF-expressing lymphocytes in the recipients of BM and SP from WT-BALB/c mice, while the bile ducts were not destroyed even by infiltrating MIF-deficient lymphocytes in the recipients of BM and SP from MIF KO mice. Therefore, these findings suggest that MIF has an effect on the development of aGVHD in a murine model of allogeneic stem cell transplantation.

Trauma: the role of the innate immune system

Immune dysfunction can provoke (multiple) organ failure in severely injured patients. This dysfunction manifests in two forms, which follow a biphasic pattern. During the first phase, in addition to the injury by trauma, organ damage is caused by the immune system during a systemic inflammatory response. During the second phase the patient is more susceptible for sepsis due to host defence failure (immune paralysis). The pathophysiological model outlined in this review encompasses etiological factors and the contribution of the innate immune system in the end organ damage. The etiological factors can be divided into intrinsic (genetic predisposition and physiological status) and extrinsic components (type of injury or "traumaload" and surgery or "intervention load"). Of all the factors, the intervention load is the only one which, can be altered by the attending emergency physician. Adjustment of the therapeutic approach and choice of the most appropriate treatment strategy can minimize the damage caused by the immune response and prevent the development of immunological paralysis. This review provides a pathophysiological basis for the damage control concept, in which a staged approach of surgery and post-traumatic immunomonitoring have become important aspects of the treatment protocol. The innate immune system is the main objective of immunomonitoring as it has the most prominent role in organ failure after trauma. Polymorphonuclear phagocytes and monocytes are the main effector-cells of the innate immune system in the processes that lead to organ failure. These cells are controlled by cytokines, chemokines, complement factors and specific tissue signals. The contribution of tissue barrier integrity and its interaction with the innate immune system is further evaluated.

Macrophage migration inhibitory factor and glucocorticoid sensitivity

Glucocorticoids (GCs) are widely used in the treatment of inflammatory diseases including rheumatoid arthritis (RA). Treatment with GC is associated with significant dose-dependent side-effects. The pro-inflammatory cytokine macrophage migration inhibitory factor (MIF) has emerged in recent years as a candidate factor which could regulate GC sensitivity. MIF is induced by GC, and is able to override anti-inflammatory actions of GCs. In this review, we summarize the pro-inflammatory actions of MIF with respect to RA, describe the interactions between MIF and GC and examine new evidence, which identifies MIF as a specific target for steroid sparing.

New insights on macrophage migration inhibitory factor: Based on molecular and functional analysis of its homologue of Chinese amphioxus

Macrophage migration inhibitory factor (MIF) is an intricate cytokine. Many questions about it are not fully resolved. In order to identify the role of MIF in Chinese amphioxus, its genomic organization, transcription pattern and enzymatic activity were studied. It's found that MIF has multi-copy gene number in the Chinese amphioxus genome and special transcription pattern in reproductive organs. Interestingly, the recombinant Bbt-MIF has tantomerase and redox activity, but fails to utilize GSH to reduce insulin instead of DTT, strikingly different from MIF in mammalian. All these results indicate that MIF gene must have undergone important changes in structure and function during the transition of invertebrate/vertebrate and might exert important role in this primitive species, which may be quite different from those found in vertebrate.

A critical role for the host mediator macrophage migration inhibitory factor in the pathogenesis of malarial anemia

The pathogenesis of malarial anemia is multifactorial, and the mechanisms responsible for its high mortality are poorly understood. Studies indicate that host mediators produced during malaria infection may suppress erythroid progenitor development (Miller, K.L., J.C. Schooley, K.L. Smith, B. Kullgren, L.J. Mahlmann, and P.H. Silverman. 1989. Exp. Hematol. 17:379–385; Yap, G.S., and M.M. Stevenson. 1991. Ann. NY Acad. Sci. 628:279–281). We describe an intrinsic role for macrophage migration inhibitory factor (MIF) in the development of the anemic complications and bone marrow suppression that are associated with malaria infection. At concentrations found in the circulation of malaria-infected patients, MIF suppressed erythropoietin-dependent erythroid colony formation. MIF synergized with tumor necrosis factor and γ interferon, which are known antagonists of hematopoiesis, even when these cytokines were present in subinhibitory concentrations. MIF inhibited erythroid differentiation and hemoglobin production, and it antagonized the pattern of mitogen-activated protein kinase phosphorylation that normally occurs during erythroid progenitor differentiation. Infection of MIF knockout mice with Plasmodium chabaudi resulted in less severe anemia, improved erythroid progenitor development, and increased survival compared with wild-type controls. We also found that human mononuclear cells carrying highly expressed MIF alleles produced more MIF when stimulated with the malarial product hemozoin compared with cells carrying low expression MIF alleles. These data suggest that polymorphisms at the MIF locus may influence the levels of MIF produced in the innate response to malaria infection and the likelihood of anemic complications.

Migration inhibitory factor up-regulates vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 via Src, PI3 kinase, and NFkappaB

Cell adhesion molecules are critical in monocyte (MN) recruitment in immune-mediated and hematologic diseases. We investigated the novel role of recombinant human migration inhibitory factor (rhMIF) in up-regulating vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) and their signaling pathways in human MNs. rhMIF-induced expression of VCAM-1 and ICAM-1 was significantly higher compared with nonstimulated MNs. rhMIF induced MN VCAM-1 and ICAM-1 expression in a concentration-dependent manner (P < .05). Antisense oligodeoxynucleotides (ODNs) and inhibitors of Src, PI3K, p38, and NFkappaB significantly reduced rhMIF-induced MN VCAM-1 and ICAM-1 expression (P < .05). However, Erk1/2 and Jak2 were not involved. Silencing RNA directed against MIF, and inhibitors of Src, PI3K, NFkappaB, anti-VCAM-1, and anti-ICAM-1 significantly inhibited rhMIF-induced adhesion of HL-60 cells to human dermal microvascular endothelial cells (HMVECs) or an endothelial cell line, HMEC-1, in cell adhesion assays, suggesting the functional significance of MIF-induced adhesion molecules (P < .05). rhMIF also activated MN phospho-Src, -Akt, and -NFkappaB in a time-dependent manner. rhMIF induced VCAM-1 and ICAM-1 up-regulation in 12 hours via Src, PI3K, and NFkappaB as shown by Western blotting and immunofluorescence. MIF and MIF-dependent signaling pathways may be a potential target for treating diseases characterized by up-regulation of cell adhesion molecules.

Macrophage migration inhibitory factor interacts with HBx and inhibits its apoptotic activity

HBx, a transcriptional transactivating protein of hepatitis B virus (HBV), is required for viral infection and has been implicated in virus-mediated liver oncogenesis. However, the precise molecular mechanism remains largely elusive. We used the yeast two-hybrid system to identify that HBx interacts with MIF directly. Macrophage migration inhibitory factor (MIF) is implicated in the regulation of inflammation, cell growth, and even tumor formation. The interaction between HBx and MIF was verified with co-immunoprecipitation, GST pull-down, and cellular colocalization. The expression of MIF was up-regulated in HBV particle producing cell 2.2.15 compared with HepG2 cell. Both HBx and MIF cause HepG2 cell G(0)/G(1) phase arrest, proliferation inhibition, and apoptosis. However, MIF can counteract the apoptotic effect of HBx. These results may provide evidence to explain the link between HBV infection and hepatocellular carcinoma.