Parasitic organisms have evolved specialized strategies to evade immune defense mechanisms. We describe herein an ortholog of the cytokine, macrophage migration inhibitory factor (MIF), which is produced by the obligate intracellular parasite, Leishmania major. The Leishmania MIF protein, Lm1740MIF, shows significant structural homology with human MIF as revealed by a high-resolution x-ray crystal structure (1.03 A). Differences between the two proteins in the N-terminal tautomerization site are evident, and we provide evidence for the selective, species-specific inhibition of MIF by small-molecule antagonists that target this site. Lm1740MIF shows significant binding interaction with the MIF receptor, CD74 (K(d) = 2.9 x 10(-8) M). Like its mammalian counterpart, Lm1740MIF induces ERK1/2 MAP kinase activation in a CD74-dependent manner and inhibits the activation-induced apoptosis of macrophages. The ability of Lm1740MIF to inhibit apoptosis may facilitate the persistence of Leishmania within the macrophage and contribute to its evasion from immune destruction.

Despite the existence of a large body of information on the subject, the mechanisms of opiate tolerance and dependence are not yet fully understood. Although the traditional mechanisms of receptor down-regulation and desensitization seem to play a role, they cannot entirely explain the phenomena of tolerance and dependence. Therefore, other mechanisms, such as the presence of antiopiate systems and the coupling of opiate receptors to alternative G-proteins, should be considered. A further complication of studies of opiate tolerance and dependence is the multiplicity of endogenous opiate receptors and peptides. This review will focus on the endogenous opioid system--peptides, receptors, and coupling of receptors to intracellular signaling via G-proteins--in the context of their roles in tolerance and dependence. Opioid peptides include the recently discovered endomorphins and those encoded by three known genes--pro-opiomelanocortin, pro-enkephalin, and pro-dynorphin. They bind to three types of receptors--mu, delta, and kappa. Each of the receptor types is further divided into multiple subtypes. These receptors are widely known to be coupled to G-proteins of the Gi and Go subtypes, but an increasing body of results suggests coupling to other G-proteins, such as Gs. The coupling of opiate receptors to Gs, in particular, has implications for tolerance and dependence. Alterations at the receptor and transduction level have been the focus of many studies of opiate tolerance and dependence. In these studies, both receptor down-regulation and desensitization have been demonstrated in vivo and in vitro. Receptor down-regulation has been more easily observed in vitro, especially in response to morphine, a phenomenon which suggests that some factor which is missing in vitro prevents receptors from down-regulating in vivo and may play a critical role in tolerance and dependence. We suggest that antiopiate peptides may operate in vivo in this capacity, and we outline the evidence for the antiopiate properties of three peptides: neuropeptide FF, orphanin FQ/nociceptin, and Tyr-W-MIF-1. In addition, we provide new results suggesting that Tyr-W-MIF-1 may act as an antiopiate at the cellular level by inhibiting basal G-protein activation, in contrast to the activation of G-proteins by opiate agonists.

First identified nearly 40 years ago, macrophage migration inhibitory factor (MIF) is a potent pro-inflammatory cytokine and is an essential component of immune and inflammatory responses. Recent studies suggest that MIF may also contribute to multiple aspects of tumor progression and neoplasia. This review will attempt to summarize these findings focusing on MIF's ability to modulate cell proliferation, tumor angiogenesis and tumor suppressor activity.

A man from Chile developed an aggressive mature T cell leukemia associated with marked eosinophilia. The neoplastic lymphocytes were of T helper surface phenotype, and they expressed the p24 and p19 antigens of human T cell leukemia virus (HTLV). A cell line (ME) was established from the patient's peripheral blood cells that was initially composed of eosinophils and T and B lymphocytes. The B lymphocytes of the cell line are polyclonal and contain Epstein-Barr virus (EBV) DNA. Many of the T lymphocytes, a few of the B lymphocytes, and none of the eosinophils express HTLV p19 and p24 antigens. By 6 months of culture, the ME line no longer contained eosinophils. A variant line of ME was established; this variant (ME-2) is notable because the cells (greater than 80%) adhere tightly to the bottom of the culture flask; they do not express T lymphocyte markers, but 30% of the cells contain cytoplasmic mu heavy immunoglobulin chains. These pre-B and null lymphocytes contain p19 and p24 antigens (80% of cells), have the HTLV-I genome, and are able to transform normal T lymphocytes in vitro. We isolated a B lymphocyte clone (11A) from ME that expresses cytoplasmic immunoglobulin (70% of cells) and p19 and p24 antigens (75% of cells), contains the EBV and HTLV genomes, and can transform T lymphocytes from normal volunteers. These data show that B lymphocytes can be infected with HTLV, although no disease of HTLV-infected B lymphocytes has been reported. The T lymphocytes from normal adult peripheral blood were easily immortalized (about 70% efficiency) by cocultivation with lethally irradiated ME cells. Twenty-five of 27 of the transformant lines were composed of T lymphocytes with helper antigens, and two of the lines were of T suppressor antigen phenotype. All the cell lines that were tested constitutively produce lymphokines, including colony-stimulating factor (CSF), erythroid-potentiating activity (EPA), macrophage migration-inhibitory factory (MIF), neutrophil-inhibitory factor (NIF), and differentiation-inducing factor (DIF).

There is a large inter-subject variability in serum creatine kinase (CK) response after eccentric exercise. This study examined and compared the variability of CK activity, other serum protein increases (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, aldolase, myoglobin),changes in muscle damage indicators (maximal isometric force: MIF, relaxed and flexed elbow joint angle: RANG and FANG, circumference: CIR, and muscle soreness level: SOR), and changes in magnetic resonance (MR) images. Ten male subjects (21.7 +/- 1.6 yrs) performed 24 maximal eccentric actions of the elbow flexors, and measurements except MR images were taken immediately before and after, and for 10 days after exercise. MR images were taken 7 days after exercise. A large variability in peak CK response (236 - 25,244 IU.I(-1) was found among subjects. Spearman rank-order correlation coefficients (r) revealed significant correlations of peak CK with peak serum protein levels (r = 0.79-0.95), peak changes in MIF (r = 0.73-0.79), RANG (r = 0.69), and CIR (r = 0.91). The higher the peak CK levels, the more profound the abnormality in the MR images and the larger the changes in MR signal intensity (r = 0.90-0.94). It is concluded that the large variability in CK response after exercise seems to be related to the variability in exercise-induced muscle damage.

Macrophage migration inhibitory factor (MIF), which inhibits apoptosis and promotes angiogenesis, is expressed in cancers suppressing immune surveillance. Its biological role in human glioblastoma is, however, only poorly understood. We examined in-vivo expression of MIF in 166 gliomas and 23 normal control brains by immunohistochemistry. MIF immunoreactivity was enhanced in neoplastic astrocytes in WHO grade II glioma and increased significantly in higher tumour grades (III-IV). MIF expression was further assessed in 12 glioma cell lines in vitro. Quantitative RT-PCR showed that MIF mRNA expression was elevated up to 800-fold in malignant glioma cells compared with normal brain. This translated into high protein levels as assessed by immunoblotting of total cell lysates and by ELISA-based measurement of secreted MIF. Wild-type p53-retaining glioma cell lines expressed higher levels of MIF, which may be connected with the previously described role of MIF as a negative regulator of wild-type p53 signalling in tumour cells. Stable knockdown of MIF by shRNA in glioma cells significantly increased tumour cell susceptibility towards NK cell-mediated cytotoxicity. Furthermore, supernatant from mock-transfected cells, but not from MIF knockdown cells, induced downregulation of the activating immune receptor NKG2D on NK and CD8+ T cells. We thus propose that human glioma cell-derived MIF contributes to the immune escape of malignant gliomas by counteracting NK and cytotoxic T-cell-mediated tumour immune surveillance. Considering its further cell-intrinsic and extrinsic tumour-promoting effects and the availability of small molecule inhibitors, MIF seems to be a promising candidate for future glioma therapy.

OBJECTIVE

To investigate the role of macrophage migration inhibitory factor (MIF) as a marker of severity of systemic inflammation in patients with severe sepsis and critically ill postsurgical patients.

METHODS

Prospective observational study in consecutive patients with severe sepsis, critically ill nonseptic postsurgical patients, and healthy blood donors.

METHODS

A surgical intensive care unit of a university hospital.

METHODS

19 patients with severe sepsis, 18 critically ill nonseptic postsurgical patients, and 10 healthy blood donors.

RESULTS

MIF plasma levels of patients and participants were measured. Interleukin 6 plasma levels were monitored as a control marker of inflammation. The median MIF plasma level was four to five times higher in patients with severe sepsis (2.70 ng/ml, range 0.31-19.59) and in critically ill nonseptic postsurgical patients (2.43 ng/ml, range 0.49-4.31) than in healthy blood donors (0.56 ng/ml, range 0.16-1.68). MIF plasma levels did not differ between the patient groups.

CONCLUSIONS

MIF serves as a general marker for systemic inflammation in septic and nonseptic acute critical illness, but MIF does not discriminate for severity or differentiate between infectious and noninfectious origins of an acute critical illness.

BACKGROUND

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine and has been shown to be involved in the development of chronic murine colitis. In the +173 G/C polymorphism of the MIF gene, the presence of C creates the binding motif of activator protein 4. This study explored the association of this polymorphism with ulcerative colitis (UC).

METHODS

Genotyping was carried out, with a tetra-primer polymerase chain reaction (PCR) method, for 659 DNA specimens from 438 healthy volunteers and 221 patients with UC. Genotype distribution between cases and controls and the association of patients' genotypes with clinical parameters were statistically evaluated.

RESULTS

No significant difference in genotype distribution was found between UC patients and healthy controls. However, when the relation of the C/C genotype to clinical parameters in UC patients was evaluated by Fisher's exact test, it was found that the frequency of the C/C genotype was higher in patients with pancolitis type than in those with other types restricted to the distal or left-sided colon (odds ratio [OR], 10.781; 95% confidence interval [CI], 1.342-86.619; P = 0.0074).

CONCLUSIONS

These data suggest that the MIF -173 G/C polymorphism may be related to the extent of disease in UC in a Japanese population.

D-Dopachrome tautomerase shares a low homologous amino acid sequence (33% homology) with the macrophage migration inhibitory factor (MIF) and possesses similar tautomerase activity as well. MIF is a cytokine involved in inflammatory reactions and immune responses. Whereas recent studies have identified MIF as a pituitary hormone and immunoregulator, much less is known about the structural basis of these physiological functions and the real significance of tautomerase activity. Therefore, interest in the structure-function relationship between D-dopachrome tautomerase and MIF has increased, especially with regard to inflammation and immune responses. We have determined the X-ray crystal structure of human D-dopachrome tautomerase at 1.54 A resolution. D-Dopachrome tautomerase folds to form a homotrimer that has extensive contact between subunits by intersubunit beta-sheets. Its overall topology and trimeric formations are similar to those of human MIF. The N-terminal proline is located at the bottom of a positively charged pocket in which the conformations of Lys32 and Ser63 are highly conserved. These positively charged properties are also seen in the active site pocket of human MIF, bacterial 5-(carboxymethyl)-2-hydroxymuconate isomerase (CHMI), and 4-oxalocrotonate tautomerase (4-OT). A detailed comparison of these structures revealed significant differences in the environment around the potential active site, the intersubunit contacts, and charge distribution on the molecular surface. It can be concluded that these features are related to the physiological role and tautomerase activity of MIF and D-dopachrome tautomerase. The present structural study could be helpful for designing effective inhibitors that modulate immunoregulatory and hormone-like effects.

Helicobacter pylori may cause chronic gastritis, gastric cancer, or lymphoma. Myeloid antigen-presenting cells (APCs) are most likely involved in the induction and expression of the underlying inflammatory responses. To study the interaction of human APC subsets with H. pylori, we infected monocytes, monocyte-derived dendritic cells (DCs), and monocyte-derived (classically activated; M1) macrophages with H. pylori and analyzed phenotypic alterations, cytokine secretion, phagocytosis, and immunostimulation. Since we detected CD163(+) (alternatively activated; M2) macrophages in gastric biopsy specimens from H. pylori-positive patients, we also included monocyte-derived M2 macrophages in the study. Upon H. pylori infection, monocytes secreted interleukin-1β (IL-1β), IL-6, IL-10, and IL-12p40 (partially secreted as IL-23) but not IL-12p70. Infected DCs became activated, as shown by the enhanced expression of CD25, CD80, CD83, PDL-1, and CCR7, and secreted IL-1β, IL-6, IL-10, IL-12p40, IL-12p70, and IL-23. However, infection led to significantly downregulated CD209 and suppressed the constitutive secretion of macrophage migration inhibitory factor (MIF). H. pylori-infected M1 macrophages upregulated CD14 and CD32, downregulated CD11b and HLA-DR, and secreted mainly IL-1β, IL-6, IL-10, IL-12p40, and IL-23. Activation of DCs and M1 macrophages correlated with increased capacity to induce T-cell proliferation and decreased phagocytosis of dextran. M2 macrophages upregulated CD14 and CD206 and secreted IL-10 but produced less of the proinflammatory cytokines than M1 macrophages. Thus, H. pylori affects the functions of human APC subsets differently, which may influence the course and the outcome of H. pylori infection. The suppression of MIF in DCs constitutes a novel immune evasion mechanism exploited by H. pylori.

OBJECTIVE

Interleukin-8 (IL-8) plays an important role in the migration of inflammatory cells into the synovium and joint fluids in rheumatoid arthritis (RA). This study was undertaken to investigate the IL-8 inductive activity of the macrophage migration inhibitory factor (MIF) in RA synovial fibroblasts. The regulatory mechanism of IL-8 was compared with that of IL-1beta.

METHODS

MIF-induced IL-8 and IL-1beta transcriptional activation was studied in RA synovial fibroblasts by Northern blot analysis, enzyme-linked immunosorbent assay, and electromobility shift assay. The effect of anti-MIF antibody administration on murine passive collagen-induced arthritis (CIA) was also evaluated by histologic examination and reverse transcriptase-polymerase chain reaction.

RESULTS

MIF up-regulated the IL-8 messenger RNA (mRNA) and protein levels in a dose-dependent manner. The IL-8 mRNA up-regulation started 1 hour poststimulation by MIF, and reached a maximum level at 6 hours. IL-1beta mRNA was also up-regulated by MIF. The mRNA up-regulation of IL-8 and IL-1beta by MIF was inhibited by 2 tyrosine kinase inhibitors, a protein kinase C (PKC) inhibitor, an activator protein 1 (AP-1) inhibitor, and by an NF-kappaB inhibitor. A cAMP-dependent kinase inhibitor did not inhibit it. MIF enhanced AP-1 and NF-kappaB binding activities in a dose-dependent manner. Passive CIA enhanced mRNA levels of macrophage inflammatory protein 2 and cytokine-induced neutrophil chemoattractants and, moreover, migration and proliferation of inflammatory cells within the synovium, which were suppressed by administration of an anti-MIF antibody.

CONCLUSIONS

MIF may play an important role in the migration of inflammatory cells into the synovium of rheumatoid joints via induction of IL-8. MIF up-regulates IL-8 and IL-1beta mRNA via tyrosine kinase-, PKC-, AP-1-, and NF-kappaB-dependent pathways.

Human uveal melanoma arises in an immune privileged ocular environment in which both adaptive and innate immune effector mechanisms are suppressed. Uveal melanoma is the most common intraocular tumor in adults and is derived from tissues in the eye that produce macrophage migration-inhibitory factor (MIF), a cytokine that has recently been demonstrated to produce immediate inhibition of NK cell-mediated lytic activity. Although NK cell-mediated lysis of uveal melanomas is inhibited in the eye, melanoma cells that disseminate from the eye are at risk for surveillance by NK cells. Moreover, uveal melanoma cells demonstrate a propensity to metastasize to the liver, an organ with one of the highest levels of NK activity in the body. Therefore, we speculated that uveal melanomas produced MIF as a means of escaping NK cell-mediated lysis. Accordingly, seven primary uveal melanoma cell lines and two cell lines derived from uveal melanoma metastases were examined for their production of MIF. MIF was detected in melanoma culture supernatants by both ELISA and the classical bioassay of macrophage migration inhibition. Melanoma-derived MIF inhibited NK cell-mediated lysis of YAC-1 and uveal melanoma cells. Cell lines derived from uveal melanoma metastases produced approximately twice as much biologically active MIF as cultures from primary uveal melanomas. Inhibition of NK cell-mediated killing by uveal melanoma-derived MIF was specifically inhibited in a dose-dependent manner by anti-MIF Ab. The results suggest that human uveal melanoma cells maintain a microenvironment of immune privilege by secreting active MIF that protects against NK cell-mediated killing.

Asthma is recognized as a heterogeneous disorder, although in most patients, the clinical manifestations are effectively managed with established combination therapies. However, 5-10% of asthmatics have severe asthma, which does not respond to treatment, and these patients account for >50% of asthma-related healthcare costs. New investigations into the pathogenesis of glucocorticoid resistance in severe asthma indicate that pulmonary macrophages may play central roles in promoting airway inflammation, particularly in asthma that is resistant to steroid therapy. Importantly, factors that are linked to the activation of pulmonary macrophages may contribute to glucocorticoid resistance and severe asthma. Here, we review recent advances in understanding the roles of pulmonary macrophages in the mechanisms of glucocorticoid resistance and the pathogenesis of severe asthma. We discuss the role of macrophage phenotype, infection, IFN-γ, LPS, associated signaling pathways, TNF-α, MIF, and other macrophage-associated factors. Understanding the pathogenesis of steroid-resistant severe asthma will contribute to the identification of optimal therapeutic strategies for the effective management of the disease.

Macrophage migration inhibitory factor (MIF) is a ubiquitous protein that is found in virtually all cells. Its precise function in the majority of cells is not known, but studies performed over the last decade indicate that it is a critical upstream regulator of the innate and acquired immune response. MIF is released under a variety of circumstances, regulates cytokine secretion and the expression of receptors that are involved in innate immunity, inhibits p53 function, and activates components of the mitogen-activated protein kinase and Jun-activation domain-binding protein-1 (Jab-1) pathways. Compelling in vitro and in vivo evidence has focused attention on this protein as a new therapeutic target for inflammatory and autoimmune diseases. Unique structural features, including an intrinsic catalytic activity, offer attractive opportunities for the discovery and design of therapeutic MIF inhibitors.

The proinflammatory cytokine macrophage migration inhibitory factor (MIF) has been shown to be cardioprotective under various pathological conditions. However, the underlying mechanisms still remain elusive. In this study, we revealed that MIF deficiency overtly exacerbated abdominal aorta constriction-induced cardiac hypertrophy and contractile anomalies. MIF deficiency interrupted myocardial autophagy in hypertrophied hearts. Rapamycin administration mitigated the exacerbated hypertrophic responses in MIF(-/-) mice. Using the phenylephrine-induced hypertrophy in vitro model in H9C2 myoblasts, we confirmed that MIF governed the activation of AMP-activated protein kinase-mammalian target of rapamycin-autophagy cascade. Confocal microscopic examination demonstrated that MIF depletion prevented phenylephrine-induced mitophagy in H9C2 myoblasts. Myocardial Parkin, an E3 ubiquitin ligase and a marker for mitophagy, was significantly upregulated after sustained pressure overload, the effect of which was prevented by MIF knockout. Furthermore, our data exhibited that levels of MIF, AMP-activated protein kinase activation, and autophagy were elevated concurrently in human failing hearts. These data indicate that endogenous MIF regulates the mammalian target of rapamycin signaling to activate autophagy to preserve cardiac geometry and protect against hypertrophic responses.

The purpose of this study was to investigate changes in muscle hardness after eccentric exercise of the elbow flexors muscles that produce muscle shortening and swelling. To assess muscle hardness, a pressure method was used in which the force required to deform the tissue (skin, subcutaneous tissue, muscle) was recorded. Eleven healthy male students performed 24 maximal eccentric actions of the elbow flexor muscles with their non-dominant arms. Muscle hardness, maximal isometric force (MIF), muscle soreness, plasma creatine kinase (CK) activity, relaxed elbow joint angle (RANG), upper-arm circumference (CIR) and B-mode ultrasound transverse images were measured before, immediately after, and 1-5 days after exercise. A long-lasting decrease in MIF, muscle swelling shown by increases in CIR and muscle thickness, large increases in plasma CK activity, and development of muscle soreness indicated that damage occurred to the elbow flexor muscles. The RANG had decreased by approximately 20 degrees at 1-3 days after exercise and showed a gradual recovery thereafter. The CIR increased gradually after exercise and peaked on day 5 post-exercise, the mean amount of increase in CIR being 18 mm. Muscle hardness measured at the relaxed elbow position did not change until 3 days after exercise, but increased significantly (P < 0.01) on days 4 and 5 post-exercise. On the other hand, muscle hardness measured when forcibly extending the shortened elbow joint increased significantly (P < 0.01) with time and peaked at 3 days after exercise. Muscle hardness assessed by the pressure method seems to reflect changes in muscle stiffness and swelling.

Tumor-derived growth factors and cytokines stimulate neoangiogenesis from surrounding capillaries to support tumor growth. Recent studies have revealed that macrophage migration inhibitory factor (MIF) expression is increased in lung cancer, particularly non-small cell lung carcinomas (NSCLC). Because MIF has important autocrine effects on normal and transformed cells, we investigated whether autocrine MIF and its only known family member, D-dopachrome tautomerase (D-DT), promote the expression of proangiogenic factors CXCL8 and vascular endothelial growth factor in NSCLC cells. Our results demonstrate that the expression of CXCL8 and vascular endothelial growth factor are strongly reliant upon both the individual and cooperative activities of the two family members. CXCL8 transcriptional regulation by MIF and D-DT appears to involve a signaling pathway that includes the activation of JNK, c-jun phosphorylation, and subsequent AP-1 transcription factor activity. Importantly, HUVEC migration and tube formation induced by supernatants from lung adenocarcinoma cells lacking either or both MIF and D-DT are substantially reduced when compared with normal supernatants. Finally, we demonstrate that the cognate MIF receptor, CD74, is necessary for both MIF- and D-DT-induced JNK activation and CXCL8 expression, suggesting its potential involvement in angiogenic growth factor expression. This is the first demonstration of a biological role for D-DT, and its synergism with MIF suggests that the combined therapeutic targeting of both family members may enhance current anti-MIF-based therapies.

MIF is a proinflammatory cytokine and is implicated in cancer. A higher MIF level is found in many human cancer and cancer-prone inflammatory diseases, including chronic pancreatitis and pancreatic cancer. We tested the hypothesis that MIF contributes to pancreatic cancer aggressiveness and predicts disease outcome in resected cases. Consistent with our hypothesis we found that an elevated MIF mRNA expression in tumors was significantly associated with poor outcome in resected cases. Multivariate Cox-regression analysis further showed that MIF is independently associated with patients' survival (HR = 2.26, 95% CI = 1.17-4.37, p = 0.015). Mechanistic analyses revealed that MIF overexpression decreased E-cadherin and increased vimentin mRNA and protein levels in pancreatic cancer cell lines, consistent with the features of epithelial-to-mesenchymal transition (EMT). Furthermore, MIF-overexpression significantly increased ZEB1/2 and decreased miR-200b expression, while shRNA-mediated inhibition of MIF increased E-cadherin and miR-200b expression, and reduced the expression of ZEB1/2 in Panc1 cells. Re-expression of miR-200b in MIF overexpressing cells restored the epithelial characteristics, as indicated by an increase in E-cadherin and decrease in ZEB1/2 and vimentin expression. A reduced sensitivity to the chemotherapeutic drug, gemcitabine, occurred in MIF-overexpressing cells. Indicative of an increased malignant potential, MIF over-expressing cells showed significant increase in their invasion ability in vitro, and tumor growth and metastasis in an orthotopic xenograft mouse model. These results support a role of MIF in disease aggressiveness, indicating its potential usefulness as a candidate target for designing improved treatment in pancreatic cancer.

OBJECTIVE

Determining the genetic changes associated with the development of metastatic prostate cancer is of utmost importance in patient prognosis and therapy. Our goal is to identify genes whose enhanced expression is associated with metastatic prostate cancer.

METHODS

Total ribonucleic acid was isolated from prostatic tissue exhibiting no histologic evidence of carcinoma and from a prostatic adenocarcinoma lymph node metastasis. The differential display polymerase chain reaction (DD-PCR) technique was used to isolate genes that exhibited increased expression in the metastatic tissue sample. Isolated PCR products were cloned, sequenced, and identified by screening complementary deoxyribonucleic acid (cDNA) databases.

RESULTS

Using DD-PCR, we identified three cDNA clones that exhibit enhanced expression in metastatic prostatic tissue. Two of these cDNA clones have not been identified because they show no homology to known database sequences. The third cDNA is 166 base pairs in length and exhibits 93% homology to nucleotides 662 to 828 of human macrophage migration inhibitory factor (MIF). Slot blot analysis using RNA from various prostate-derived sources suggests that increased expression of MIF is associated with metastatic prostate cancer.

CONCLUSIONS

These results show that the DD-PCR technique is applicable for the identification and cloning of human genes that exhibit enhanced expression in prostate cancer metastases. These results indicate the possibility that MIF production by prostate cancer cells plays a role in the development of metastases. The enhanced expression of MIF by prostate cancer cells may be a potential prognostic marker for metastatic prostate cancer.

OBJECTIVE

Macrophage migration inhibitory factor (MIF) is a central mediator of innate immunity. Our aim was to investigate the triangular association between MIF genotypes, circulating MIF concentrations and incident type 2 diabetes, and to use a Mendelian randomisation approach to assess the causal role of MIF.

METHODS

Using a case-cohort design within the population-based MONICA/KORA Augsburg Study, based on 502 individuals with incident type 2 diabetes (293 men, 209 women) and 1,632 non-cases (859 men, 773 women), we determined MIF serum levels at baseline and genotyped four MIF single nucleotide polymorphisms (SNPs).

RESULTS

The C allele of SNP rs1007888 (3.8 kb 3' of the translation termination codon) was associated with increased circulating MIF. MIF genotype rs1007888CC was associated with an increased risk of type 2 diabetes in women [hazard ratio (95% CI) 1.74 (1.02-2.97)], but not in men [1.17 (0.75-1.81)]. Elevated MIF serum levels were associated with higher type 2 diabetes risk also only in women [HR (95% CI) 1.95 (1.15-3.29) comparing extreme quartiles after multiple adjustment], but not in men (p for interaction 0.039). The association between MIF levels and incident type 2 diabetes was significantly higher in obese women (111 cases, 147 non-cases) compared with non-obese women (98 cases, 626 non-cases; p for BMI interaction 0.0002).

CONCLUSIONS

The consistent triangular relationship between genotypes, serum levels and incident type 2 diabetes in women indicates that MIF may play a causal role in the aetiology of type 2 diabetes and that elevated MIF levels confer a higher disease risk.

The recent cloning of MIF receptor fills an important gap in our understanding of the molecular biology and immunology of MIF. The MIF receptor, like MIF, does not fall into any established family of protein mediators, providing both new challenges and opportunities for the structural and functional analysis of MIF signal transduction.

BACKGROUND

Severe malarial anemia (SMA) resulting from Plasmodium falciparum infection is one of the leading causes of childhood mortality in sub-Saharan Africa. The innate immune mediator macrophage migration inhibitory factor (MIF) plays a critical role in the pathogenesis of SMA.

METHODS

To investigate the influence of MIF genetic variation on susceptibility to SMA, haplotypes of the MIF -173G/C and -794CATT5-8 polymorphisms were examined in a cohort of Kenyan children.

RESULTS

A statistically significant relationship between increasing frequencies of longer CATT repeats at -794 and increasing severity of malarial anemia was observed. In addition, there was a strong association between lower MIF concentrations and longer CATT repeats. Multivariate logistic regression analyses demonstrated that the 6G haplotype (ie, MIF -794CATT6/-173G) was associated with protection against SMA, whereas carriers of the 7C or 8C haplotype had increased risk of developing SMA. Furthermore, carriers of the 7C or 8C haplotype had reduced plasma MIF levels during acute disease.

CONCLUSIONS

The findings demonstrate that variation in the MIF promoter influences susceptibility to SMA and peripheral MIF production. However, the MIF -173 and -794 polymorphisms appear to have both independent and interactive effects on different measures of disease severity, suggesting that MIF plays a complex role in malarial pathogenesis.

The cytokine, macrophage migration inhibitory factor (MIF), is encoded in a functionally polymorphic locus and subjects with high-expression MIF alleles are at an increased risk of inflammatory disease. Severe sepsis is the leading cause of death in intensive care units, and the prevailing hypothesis is that an excessive innate response contributes to its pathogenesis. To assess if MIF alleles influence the clinical course of infection, we conducted a case-control study to assess susceptibility and a parallel inception cohort study of community-acquired pneumonia (CAP) to assess risk of severe sepsis and 90-d mortality. Two distinct polymorphisms in the MIF promoter were analyzed: a G/C transition at -173 and a CATT repeat at -794. The frequency of both polymorphisms was similar in the CAP cohort (n=1739) and controls (n=639); however, the 90-d mortality was lower for the high-expression C allele (P=0.003). This association remained significant after adjusting for demographics, comorbid conditions, and disease severity score [hazard ratio=0.64 (0.44-0.91), P=0.01]. The hazard ratio was similar in different geographic subcohorts, and the association remained significant after adjusting for false discovery. These data indicate that polymorphisms associated with higher MIF expression may have a beneficial effect in community-acquired pneumonia.

BACKGROUND

The mediator known historically as macrophage migration inhibitory factor (MIF) has been identified recently as being released into the circulation by the anterior pituitary gland as a consequence of stress or during a systemic inflammatory response. Macrophages and T cells also secrete MIF, both in response to proinflammatory factors or upon stimulation with glucocorticoids. Once released, MIF "overrides" or counterregulates the immunosuppressive effects of steroids on cytokine production and immune cellular activation. To further investigate the biology of MIF and its role in the neuroendocrine system, we have studied the regional and cellular expression of MIF in brain tissue obtained from normal rats and rats administered LPS intracisternally.

METHODS

Rat brain sections were analyzed by immunohistochemistry utilizing an affinity-purified, anti-MIF antibody raised to recombinant MIF, and by in situ hybridization using a digoxigenin-labeled, antisense MIF cRNA probe. The kinetics of MIF mRNA expression in brain were compared with that of IL-1, IL-6, and TNF-alpha by RT-PCR of total brain RNA. The cerebrospinal fluid content of MIF and TNF-alpha proteins was analyzed by Western blotting and ELISA.

RESULTS

A strong baseline expression pattern for MIF was observed in neurons of the cortex, hypothalamus, hippocampus, cerebellum, and pons. By in situ hybridization, MIF mRNA was found predominantly in cell bodies whereas MIF protein was detected mostly within the terminal fields associated with neurons. There was a marked pattern of MIF immunoreactivity within the mossy fibers of the dentate gyrus and dendrites of the hippocampal CA3 field. These structures have been shown previously to be involved in glucocorticoid-induced tissue damage within the hippocampus, suggesting an association between MIF and targets of glucocorticoid action. The intracisternal injection of LPS increased MIF mRNA and protein expression in brain and MIF immunoreactivity was due in part to infiltrating monocytes/macrophages. MIF protein also was found to be rapidly released into the cerebrospinal fluid. This response corresponded with that of LPS-induced cytokine release and MIF mRNA expression increased in a distribution that colocalized in large part with that of TNF-alpha, IL-1 beta, and IL-6.

CONCLUSIONS

The significant levels of baseline and inducible MIF expression in the brain and its regional association with glucocorticoid action underscore the importance of this mediator as a physiological regulator of the inflammatory stress response and further define its role within the neuroendocrine system.