Showing papers by "Richard Bucala published in 2008"

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

Abstract: 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

A Novel, Macrophage Migration Inhibitory Factor Suicide Substrate Inhibits Motility and Growth of Lung Cancer Cells

Abstract: Although chemokine and growth factor receptors are attractive and popular targets for cancer therapeutic intervention, structure-based targeting of the ligands themselves is generally not considered practical. New evidence indicates that a notable exception to this is macrophage migration inhibitory factor (MIF). MIF, an autocrine- and paracrine-acting cytokine/growth factor, plays a pivotal role in both the initiation and maintenance of neoplastic diseases. MIF possesses a nonphysiologic enzymatic activity that is evolutionarily well-conserved. Although small molecule antagonists of MIFs enzymatic active site have been reported to inhibit biological activities of MIF, universally high IC(50)s have limited their clinical appeal. Using a computational virtual screening strategy, we have identified a unique small molecule inhibitor that serves as a suicide substrate for MIF, resulting in the covalent modification of the catalytically active NH(2)-terminal proline. Our studies further reveal that this compound, 4-iodo-6-phenylpyrimidine (4-IPP), is approximately 5x to 10x times more potent in blocking MIF-dependent catalysis and lung adenocarcinoma cell migration and anchorage-independent growth than the prototypical MIF inhibitor, ISO-1. Finally, using an in silico combinatorial optimization strategy, we have identified four unique congeners of 4-IPP that exhibit MIF inhibitory activity at concentrations 10x to 20x lower than that of parental 4-IPP.

Macrophage Migration Inhibitory Factor Contributes to the Immune Escape of Ovarian Cancer by Down-Regulating NKG2D

Abstract: The proinflammatory cytokine macrophage migration inhibitory factor (MIF) stimulates tumor cell proliferation, migration, and metastasis; promotes tumor angiogenesis; suppresses p53-mediated apoptosis; and inhibits antitumor immunity by largely unknown mechanisms. We here describe an overexpression of MIF in ovarian cancer that correlates with malignancy and the presence of ascites. Functionally, we find that MIF may contribute to the immune escape of ovarian carcinoma by transcriptionally down-regulating NKG2D in vitro and in vivo which impairs NK cell cytotoxicity toward tumor cells. Together with the additional tumorigenic properties of MIF, this finding provides a rationale for novel small-molecule inhibitors of MIF to be used for the treatment of MIF-secreting cancers.

Acute Lung Injury Induced by Lipopolysaccharide Is Independent of Complement Activation

Abstract: 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.

Macrophage migration inhibitory factor and autism spectrum disorders.

Abstract: OBJECTIVE. Autistic spectrum disorders are childhood neurodevelopmental disorders characterized by social and communicative impairment and repetitive and stereotypical behavior. Macrophage migration inhibitory factor (MIF) is an upstream regulator of innate immunity that promotes monocyte/macrophage-activation responses by increasing the expression of Toll-like receptors and inhibiting activation-induced apoptosis. On the basis of results of previous genetic linkage studies and reported altered innate immune response in autism spectrum disorder, we hypothesized that MIF could represent a candidate gene for autism spectrum disorder or its diagnostic components. METHODS. Genetic association between autism spectrum disorder and MIF was investigated in 2 independent sets of families of probands with autism spectrum disorder, from the United States (527 participants from 152 families) and Holland (532 participants from 183 families). Probands and their siblings, when available, were evaluated with clinical instruments used for autism spectrum disorder diagnoses. Genotyping was performed for 2 polymorphisms in the promoter region of the MIF gene in both samples sequentially. In addition, MIF plasma analyses were conducted in a subset of Dutch patients from whom plasma was available. RESULTS. There were genetic associations between known functional polymorphisms in the promoter for MIF and autism spectrum disorder–related behaviors. Also, probands with autism spectrum disorder exhibited higher circulating MIF levels than did their unaffected siblings, and plasma MIF concentrations correlated with the severity of multiple autism spectrum disorder symptoms. CONCLUSIONS. These results identify MIF as a possible susceptibility gene for autism spectrum disorder. Additional research is warranted on the precise relationship between MIF and the behavioral components of autism spectrum disorder, the mechanism by which MIF contributes to autism spectrum disorder pathogenesis, and the clinical use of MIF genotyping.

A Leishmania Ortholog of Macrophage Migration Inhibitory Factor Modulates Host Macrophage Responses

Abstract: 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 (Kd = 2.9 × 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.

Cooperative Regulation of Non-Small Cell Lung Carcinoma Angiogenic Potential by Macrophage Migration Inhibitory Factor and Its Homolog, d-Dopachrome Tautomerase

Abstract: 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.

Circulating Fibrocytes: Cellular Basis for NSF

Abstract: Since the discovery of the circulating fibrocyte as a collagen-producing cell of the peripheral blood, the physiologic and pathologic role of this unique cell population has grown steadily. The present review summarizes the known biology of fibrocytes and discusses evidence for their role in the pathogenesis of nephrogenic systemic fibrosis. Possible mechanisms by which gadolinium may influence the activation or trafficking properties of fibrocytes leading to tissue fibrosis are discussed.

The renin-angiotensin system contributes to renal fibrosis through regulation of fibrocytes.

Abstract: BACKGROUND The renin-angiotensin system is a major pathway in the pathogenesis of cardiovascular and renal diseases. Bone marrow-derived fibrocytes, which are dual positive for CD45 and type I collagen, are now considered to contribute to the pathogenesis of various fibrotic diseases. We hypothesized that fibrocytes might contribute to renal fibrosis by an angiotensin II dependent pathway. RESULTS In murine models of renal fibrosis, angiotensin II type 2 receptor (AT2R)-deficient mice, when compared with wild-type mice, showed increased renal fibrosis and fibrocyte infiltration with a concomitant upregulation of renal transcripts of procollagen type I (alpha) (COL1A1). Fibrocyte numbers in the bone marrow also were increased in AT2R-deficient mice. By contrast, pharmacological inhibition of angiotensin II type 1 receptor (AT1R) with valsartan reduced the degree of renal fibrosis and the number of fibrocytes in both the kidney and the bone marrow. In isolated human fibrocytes, inhibition of AT2R signaling increased the angiotensin II-stimulated expression of type I collagen, whereas inhibition of AT1R decreased collagen synthesis. These results suggest that AT1R/AT2R signaling may contribute to the pathogenesis of renal fibrosis by at least two mechanisms: by regulating the number of fibrocytes in the bone marrow, and by activation of fibrocytes.

Tumor growth-promoting properties of macrophage migration inhibitory factor.

Abstract: Macrophage migration inhibitor factor (MIF) is a highly conserved and evolutionarily ancient mediator with pleiotropic effects that has been implicated in tumor growth and progression. MIF's function is unique among cytokines and its effects extend to multiple processes fundamental to tumorigenesis such as tumor proliferation, evasion of apoptosis, angiogenesis and invasion. These pleiotropic functional aspects are paralleled by MIF's unique signaling properties, which involve activation of the ERK-1/2 and AKT pathways and the regulation of JAB1, p53, SCF ubiquitin ligases and HIF-1. These properties reflect features central to growth regulation, apoptosis and cell cycle control than is typical for an immune cytokine. The significance of these pro-tumorigenic properties has found support in several in vitro and in vivo models of cancer and in the positive association between MIF production and tumor aggressiveness and metastatic potential in a variety of human tumors.

Macrophage migration inhibitory factor (MIF) is critical for the host resistance against Toxoplasma gondii

Abstract: Macrophage migration inhibitory factor (MIF) exerts either a protective or a deleterious role in the immune response to different pathogens We ana- lyzed herein the role of MIF in the host control of toxoplasmosis using MIF / mice backcrossed to ei- ther the BALB/c or the C57BL/6 genetic backgrounds Both, wild-type (WT) BALB/c and MIF / BALB/c mice were susceptible to infection with highly virulent RH as well as moderately virulent ME49 strains of T gondii MIF / mice, however, showed greater liver damage and more brain cysts, produced less proinflam- matory cytokines, and succumbed significantly faster than WT mice Bone marrow-derived dendritic cells (BMDCs) from MIF / mice produced less interleu- kin-1, interleukin-12, and tumor necrosis factor- than WT BMDCs after stimulation with soluble Toxo- plasma antigen (STAg) Similar observations were made in CD11c low-density cells isolated from the spleens of MIF / mice challenged with STAg MIF / C57BL/6 mice succumbed to ME49 infection faster than their WT counterparts C57BL/6 mice that suc- cumbed to infection with the ME49 strain produced less MIF than resistant BALB/c mice similarly infected Interestingly, an analysis of brains from patients with cerebral toxoplasmosis showed low levels of MIF ex- pression Together, these findings demonstrate that MIF plays a critical role in mediating host resistance against T Gondii—Flores, M, Saavedra, R, Bautista, R, Viedma, R, Tenorio, E P, Leng, L, Sanchez, Y, Juarez, I, Satoskar, A A, Shenoy, A S, Terrazas, L I, Bucala, R, Barbi J, Satoskar, A R, Rodriguez-Sosa, M Macrophage migration inhibitory factor (MIF) is criti- cal for the host resistance against Toxoplasma gondii FASEB J 22, 000 - 000 (2008)

A Role for Macrophage Migration Inhibitory Factor in the Neonatal Respiratory Distress Syndrome

Abstract: 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 p

The conformational flexibility of the carboxy terminal residues 105-114 is a key modulator of the catalytic activity and stability of macrophage migration inhibitory factor.

Abstract: Macrophage migration inhibitory factor (MIF) is a multifunctional protein and a major mediator of innate immunity. Although X-ray crystallography revealed that MIF exists as a homotrimer, its oligomerization state in vivo and the factors governing its oligomerization and stability remain poorly understood. The C-terminal region of MIF is highly conserved and participates in several intramolecular interactions that suggest a role in modulating the stability and biochemical activity of MIF. To determine the importance of these interactions, point mutations (A48P, L46A), insertions (P107) at the monomer-monomer interfaces, and C-terminal deletion (Delta 110-114NSTFA and Delta 105-114NVGWNNSTFA) variants were designed and their structural properties, thermodynamic stability, oligomerization state, catalytic activity and receptor binding were characterized using a battery of biophysical methods. The C-terminal deletion mutants DeltaC5 huMIF 1-109 and DeltaC10 huMIF 1-104 were enzymatically inactive and thermodynamically less stable than wild type MIF. Analytical ultracentrifugation studies demonstrate that both C-terminal mutants sediment as trimers and exhibit similar binding to CD74 as the wild type protein. Disrupting the conformation of the C-terminal region 105-114 and increasing its conformational flexibility through the insertion of a proline residue at position 107 was sufficient to reproduce the structural, biochemical and thermodynamic properties of the deletion mutants. P107 MIF forms an enzymatically inactive trimer and exhibits reduced thermodynamic stability relative to the wild type protein. To provide a rationale for the changes induced by these mutations at the molecular level, we also performed molecular dynamics simulations on these mutants in comparison to the wild type MIF. Together, our studies demonstrate that intersubunit interactions involving the C-terminal region 105-114, including a salt-bridge interaction between Arg73 of one monomer and the carboxy terminus of a neighboring monomer, play critical roles in modulating tertiary structure stabilization, enzymatic activity, and thermodynamic stability of MIF, but not its oligomerization state and receptor binding properties. Our results suggest that targeting the C-terminal region could provide new strategies for allosteric modulation of MIF enzymatic activity and the development of novel inhibitors of MIF tautomerase activity.

A time capsule for rheumatology.

Abstract: This communication is based on a review of the contents of Arthritis and Rheumatism (AR only 9 authors (2%) were not North Americans In contrast, one issue (May 2007) contained 37 full-length articles, 24 authored by nonNorth Americans (Asians, Europeans, Australians) The charge to each past AR before doing that, it is appropriate to comment briefly on the themes that were dominant in work published in the Journal during the early 1970s Coincident with the founding of AR Jane E Salmon, MD: Hospital for Special Surgery, New York, New York; Richard Bucala, MD, PhD: Yale University School of Medicine, New Haven, Connecticut Address correspondence to Charles L Christian, MD, University of Florida Health Science Center, 653 West 8th Street, Jacksonville, FL 32209 E-mail: charleschristian@jaxufledu Submitted for publication September 12, 2007; accepted September 12, 2007

Aging-associated Alteration in the Cardiac MIF-AMPK Cascade in Response to Ischemic Stress

Abstract: An important role for a macrophage migration inhibitory factor (MIF)-AMP-activated protein kinase (AMPK) signaling pathway in ameliorating myocardial damage following ischemia/reperfusion has been described. An aging-associated reduction in AMPK activity may be associated with a decline in the ability of cardiac cells to activate the MIF-AMPK cascade, thereby resulting in reduced tolerance to ischemic insults. To test this hypothesis, in vivo regional ischemia was induced by occlusion of the left anterior descending (LAD) coronary artery in young (4-6 months) and aged (24-26 months) mice. The ischemic AMPK activation response was impaired in aged hearts compared to young ones (p<0.01). Notably, cardiac MIF expression in aged hearts was lower than in young hearts (p<0.01). Dual staining data clearly demonstrated larger infarct size in aged hearts following ischemia and reperfusion compared to young hearts (p<0.05). Ischemia-induced AMPK activation in MIF knock out (MIF KO) hearts was blunted, leading to greater contractile dysfunction of MIF KO cardiomyocytes during hypoxia than that of wild type (WT) cardiomyocytes. Finally exogenous recombinant MIF significantly reversed the contractile dysfunction of aged cardiomyocytes in response to hypoxia. We conclude that an aging-associated reduction in ischemic AMPK activation contributes to ischemic intolerance in aged hearts.