Role of macrophage migration inhibitory factor in the regulation of the immune response.
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Amino Acid Sequence↗
Biomedical subjects
R Bucala
Publications and source records attributed to R Bucala.
Macrophage migration inhibitory factor: a regulator of glucocorticoid activity with a critical role in inflammatory disease.
Macrophage migration inhibitory factor (MIF) was one of the first cytokines to be identified. In the early 1990s it was 'rediscovered' as a hormone that is secreted by the anterior pituitary gland and counter-regulates the anti-inflammatory effects of glucocorticoids. We now know that glucocorticoids stimulate the release of MIF from T cells and macrophages; this appears to be a physiological response to override the effects of glucocorticoids at the inflammatory site. However, this response can become pathological in acute respiratory distress syndrome (ARDS), in which high concentrations of MIF in the alveoli might contribute to ARDS pathogenesis. New insights into the structure and function of MIF, and the possibility of increasing the efficacy of glucocorticoids in the clinic by inhibiting MIF, are discussed in this review.
Animals↗
Efficient scavenging of fatty acid oxidation products by aminoguanidine.
Lipid oxidation leads to the formation of reactive aldehydes that may play an important role in atherogenesis by altering the normal pathway of lipoprotein metabolism and by exerting toxic effects on vascular wall components. Recent studies indicate that advanced glycation end products, which form spontaneously from the reaction of reducing sugars with amino groups, may promote oxidative damage in vivo. Moreover, the pharmacological inhibitor of advanced glycation aminoguanidine has been shown to lower circulating low-density lipoprotein levels in human subjects and to inhibit certain oxidative reactions in vitro. To define more precisely the potential interaction of AG with oxidized lipids, we have studied and identified the major products that form from the reaction of AG with the oxidation products 4-hydroxynonenal and malondialdehyde. AG was found to be an efficient scavenger of alpha,beta-unsaturated aldehydes when compared to nucleophilic amino acids (Cys, Lys, His), suggesting that one of its mechanisms of action in vivo is to protect tissue constituents from the damaging effects of oxidative stress.
Aldehydes↗
Reduction of plasma apolipoprotein-B by effective removal of circulating glycation derivatives in uremia.
Patients with diabetes and renal insufficiency (Db/ESRD), a group subject to accelerated atherosclerosis exhibit marked increases in the levels of circulating, glycation-derived reactive substances, termed advanced glycation endoproducts (AGEs). These products have been previously shown to react covalently with apoliprotein B (ApoB) to form AGE-ApoB, a modification that results in delayed low density lipoprotein (LDL) clearance and possibly to dyslipidemia. Because the effect of hemodialysis on AGE removal was shown to be unsatisfactory, based on single intradialytic studies, we examined the effect of long-term hemodialysis therapy on serum AGE-ApoB levels, as well as on total serum ApoB of 25 Db/ESRD patients treated by two types of hemodialysis filters, the Fresenius Inc. F8, as the low flux (LF), or high-flux polysulfone AN69 (HF) for two months using an AGE-specific ELISA. At the end of eight weeks, circulating AGE-ApoB levels were reduced significantly (by 35%) from baseline (P = 0.039) in patients treated by HF compared to a modest 16% reduction noted in patients treated by LF (P = 0.05) N = 12, P = 0.047). Of note, total plasma ApoB was reduced by 27% from baseline (P = 0.02) in patients treated by HF compared to a 6% reduction noted in those treated with LF (P = 0.8). In vitro comparison of AGE mass balance, and mass adsorption by the different filters revealed that the higher efficiency of HF filter was due to greater adsorption. The association of reduced AGE-ApoB levels with a decrease in total circulating ApoB by HF and not by LF dialysis suggests: (1) a causal link between AGE clearance and dyslipidemia in diabetic ESRD, and, (2) that more efficient modes of renal replacement treatment and AGE removal could significantly benefit clinical outcome.
Apolipoproteins B↗
Regulatory role for macrophage migration inhibitory factor in acute respiratory distress syndrome.
Migration inhibitory factor (MIF) is known to exert significant pro-inflammatory effects and has the potential to override the anti-inflammatory action of glucocorticoids. In this study we have identified significant quantities of MIF in the alveolar airspaces of patients with acute respiratory distress syndrome (ARDS). We show in alveolar cells from patients with ARDS that MIF augments pro-inflammatory cytokine secretion (TNF alpha and IL-8), anti-MIF significantly attenuates TNF alpha and IL-8 secretion and MIF overrides, in a concentration-related fashion, the anti-inflammatory effects of glucocorticoids. These findings suggest that MIF may act as a mediator sustaining the pulmonary inflammatory response in ARDS and that an anti-MIF strategy may represent a novel therapeutic approach in inflammatory diseases such as ARDS.
Cells, Cultured↗
Peripheral blood fibrocytes: novel fibroblast-like cells that present antigen and mediate tissue repair.
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Animals↗
Up-regulation of macrophage colony-stimulating factor (M-CSF) and migration inhibitory factor (MIF) expression and monocyte recruitment during lipid-induced glomerular injury in the exogenous hypercholesterolaemic (ExHC) rat.
Although macrophages play an important role in lipid-induced glomerular injury, we know little of the mechanisms by which hyperlipidaemia induces monocyte recruitment. This study investigated the role of M-CSF and macrophage MIF in monocyte recruitment during the development of lipid-induced glomerular injury in the susceptible ExHC rat strain. Groups of five ExHC rats were fed a high cholesterol diet (HCD) containing 3% cholesterol, 0.6% sodium cholate and 15% olive oil, and killed after 3 days, 1, 2 or 6 weeks. Control animals were killed on day 0 or after 6 weeks on a normal diet. Animals were hypercholesterolaemic 3 days after the induction of the HCD, but showed no change in plasma triglycerides over the 6-week period. Glomerular macrophage accumulation was first evident at 1-2 weeks and increased up to week 6, when macrophage-derived foam cells were seen in almost all glomeruli, and segmental lesions and mild proteinuria were also evident. Combined in situ hybridization and immunohistochemistry staining demonstrated that, coincident with the induction of hypercholesterolaemia on day 3, there was marked up-regulation of M-CSF and MIF mRNA expression by intrinsic glomerular cells (mostly mesangial cells and podocytes) which preceded monocyte recruitment. There was a highly significant correlation between the number of M-CSF and MIF-positive cells and glomerular macrophage accumulation over the 6-week period. Although some glomerular macrophages and foam cells exhibited M-CSF and MIF expression, the major source of these molecules was intrinsic glomerular cells. No local macrophage proliferation was observed during the development of glomerular lesions. In conclusion, hypercholesterolaemia caused marked up-regulation of M-CSF and MIF expression by intrinsic glomerular cells, which correlated with monocyte recruitment and the development of lipid-induced glomerular injury. This is the first study to implicate local synthesis of MIF in the pathogenesis of lipid-induced lesions.
Animals↗
Lipid and lipoprotein modification by advanced glycosylation end-products: role in atherosclerosis.
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Amino Acid Sequence↗
Macrophage migration inhibitory factor (MIF): a glucocorticoid counter-regulator within the immune system.
Originally described as a T lymphocyte-derived factor that inhibited the random migration of macrophages, the protein known as macrophage migration inhibitory factor (MIF) was an enigmatic cytokine for almost 3 decades. In recent years, the discovery of MIF as a product of the anterior pituitary gland and the cloning and expression of bioactive, recombinant MIF protein have led to the definition of its critical biological role in vivo. MIF has the unique property of being released from macrophages and T lymphocytes that have been stimulated by glucocorticoids. Once released, MIF overcomes the inhibitory effects of glucocorticoids on TNF alpha, IL-1 beta, IL-6, and IL-8 production by LPS-stimulated monocytes in vitro and suppresses the protective effects of steroids against lethal endotoxemia in vivo. MIF also antagonizes glucocorticoid inhibition of T-cell proliferation in vitro by restoring IL-2 and IFN-gamma production. This observation has identified a pivotal role for MIF within the immune system and fills an important gap in our understanding of the control of inflammatory and immune responses. Glucocorticoids have long been considered to be an integral component of the stress response to infection or tissue invasion and serve to modulate inflammatory and immune responses. MIF is the first mediator to be identified that can counter-regulate the inhibitory effects of glucocorticoids and thus plays a critical role in the host control of inflammation and immunity.
Amino Acid Sequence↗
Migration inhibitory factor expression in experimentally induced endotoxemia.
Macrophage migration inhibitory factor (MIF) is an important constituent of the host response to stress and infection and is the first mediator that has been identified to be released from immune cells upon stimulation with glucocorticoids. MIF also has been shown to be secreted from the anterior pituitary gland, monocytes/macrophages, and T cells activated by various proinflammatory stimuli. Once released, MIF acts to counter-regulate the inhibitory effect of glucocorticoids on inflammatory cytokine production. To characterize more precisely the role of MIF in the host response to infection, we undertook a systematic analysis of MIF expression in various organs of the rat after endotoxin (lipopolysaccharide) administration. MIF protein and mRNA were analyzed by immunohistochemistry and in situ hybridization, respectively. MIF was found to be expressed constitutively in organs such as the lung, liver, kidney, spleen, adrenal gland, and skin. Significant quantities of MIF protein were detected preformed in various cell types and appeared to be released as a consequence of endotoxemia. In virtually all tissues examined, the loss of MIF protein 6 hours after lipopolysaccharide administration was accompanied by the induction of MIF mRNA and, at 24 hours, by the restoration of immunoreactive, intracellular MIF. The constitutive production of MIF by several cell and tissue types together with its rapid release from intracellular pools distinguishes MIF from other cytokines or hormonal mediators and significantly expands the physiological role of this unique counter-regulator of glucocorticoid action.
Adrenal Glands↗
Advanced glycation end products (AGEs) co-localize with AGE receptors in the retinal vasculature of diabetic and of AGE-infused rats.
Advanced glycation end products (AGEs), formed from the nonenzymatic glycation of proteins and lipids with reducing sugars, have been implicated in many diabetic complications; however, their role in diabetic retinopathy remains largely unknown. Recent studies suggest that the cellular actions of AGEs may be mediated by AGE-specific receptors (AGE-R). We have examined the immunolocalization of AGEs and AGE-R components R1 and R2 in the retinal vasculature at 2, 4, and 8 months after STZ-induced diabetes as well as in nondiabetic rats infused with AGE bovine serum albumin for 2 weeks. Using polyclonal or monoclonal anti-AGE antibodies and polyclonal antibodies to recombinant AGE-R1 and AGE-R2, immunoreactivity (IR) was examined in the complete retinal vascular tree after isolation by trypsin digestion. After 2, 4, and 8 months of diabetes, there was a gradual increase in AGE IR in basement membrane. At 8 months, pericytes, smooth muscle cells, and endothelial cells of the retinal vessels showed dense intracellular AGE IR. AGE epitopes stained most intensely within pericytes and smooth muscle cells but less in basement membrane of AGE-infused rats compared with the diabetic group. Retinas from normal or bovine-serum-albumin-infused rats were largely negative for AGE IR. AGE-R1 and -R2 co-localized strongly with AGEs of vascular endothelial cells, pericytes, and smooth muscle cells of either normal, diabetic, or AGE-infused rat retinas, and this distribution did not vary with each condition. The data indicate that AGEs accumulate as a function of diabetes duration first within the basement membrane and then intracellularly, co-localizing with cellular AGE-Rs. Significant AGE deposits appear within the pericytes after long-term diabetes or acute challenge with AGE infusion conditions associated with pericyte damage. Co-localization of AGEs and AGE-Rs in retinal cells points to possible interactions of pathogenic significance.
Animals↗
TNF-alpha up-regulates renal MIF expression in rat crescentic glomerulonephritis.
BACKGROUND: Macrophage migration inhibitory factor (MIF) is a potent proinflammatory mediator that participates in the pathogenesis of endotoxemia and experimental crescentic glomerulonephritis. However, very little is known about how MIF production is regulated in disease. We therefore examined whether tumor necrosis factor alpha (TNF-alpha), a known inducer of MIF expression by macrophages in vitro, up-regulates local and systemic MIF expression in a macrophage-mediated rat model of crescentic glomerulonephritis. MATERIALS AND METHODS: Anti-glomerular basement membrane (GBM) glomerulonephritis was induced in groups of six primed rats. Animals were treated with 1 mg/kg soluble TNF-alpha receptor (TNFbp) or saline from the time of disease induction until they were killed on Days 1, 7, or 14. Renal MIF expression was assessed by in situ hybridization, immunohistochemistry, and ELISA, and compared with macrophage accumulation and indices of renal damage. RESULTS: Although TNFbp treatment on Day 1 of the disease had only a partial effect upon the up-regulation of glomerular MIF expression, on Days 7 to 14 it almost completely abrogated the increase in glomerular and interstitial MIF mRNA and protein expression. In addition, TNFbp treatment significantly inhibited MIF secretion by cultured glomeruli and reduced serum MIF levels. The inhibition of renal MIF expression was paralleled by a significant inhibition of glomerular and interstitial macrophage infiltration (p < 0.001 versus saline treated), a significant suppression of renal injury (proteinuria and serum creatinine), and a marked reduction in histologic damage (glomerular hypercellularity, crescent formation, and interstitial fibrosis; all p < 0.01 versus saline treated). CONCLUSIONS: This study demonstrates for the first time that TNF-alpha up-regulates local MIF expression by both infiltrating macrophages and resident kidney cells in rat crescentic glomerulonephritis. In addition, TNF-alpha regulates systemic MIF production. Thus, TNF-alpha, together with MIF, may play a pathological role in immunologically induced renal disease.
Animals↗
Immunocytochemical localization of macrophage migration inhibitory factor in human hypophysis and pituitary adenomas.
OBJECTIVE: To establish the presence of macrophage migration inhibitory factor (MIF) in human nontumorous and adenomatous pituitaries. DESIGN, SETTING, AND PATIENTS: Macrophage migration inhibitory factor was demonstrated by immunocytochemistry on paraffin sections with a polyclonal antirecombinant murine MIF using the streptavidin-biotin-peroxidase complex method. Nontumorous hypophyses (14 cases) obtained from autopsy and 54 surgically removed pituitary adenomas were studied. In nontumorous pituitaries, serial sections were immunostained for both pituitary hormones and MIF. RESULTS: Macrophage migration inhibitory factor was localized in all corticotrophs, including basophils extending into the posterior lobe, Crooke's cells, and a few thyrotrophs. The posterior lobe was immunonegative for MIF. Densely (five cases) and sparsely (six cases) granulated somatotroph and lactotroph (six cases) adenomas lacked MIF immunostaining. Macrophage migration inhibitory factor was found in 3 of 4 thyrotroph adenomas, 3 of 6 gonadotroph adenomas, 10 of 11 functioning corticotroph and 8 of 10 silent corticotroph adenomas, 3 of 3 null cell adenomas, and 3 of 3 oncocytic adenomas. The immunopositivity was diffuse or focal, and the intensity was variable. CONCLUSIONS: This study is the first to demonstrate the presence of MIF in human nontumorous and adenomatous pituitaries using an immunocytochemical staining technique.
Adenoma↗
Elevated AGE-modified ApoB in sera of euglycemic, normolipidemic patients with atherosclerosis: relationship to tissue AGEs.
BACKGROUND: Advanced glycation endproducts (AGEs) are implicated in the pathogenesis of atherosclerotic vascular disease of diabetic and nondiabetic etiology. Recent research suggests that advanced glycation of ApoB contributes to the development of hyperlipidemia. AGE-specific receptors, expressed on vascular endothelium and mononuclear cells, may be involved in both the clearance of, and the inflammatory responses to AGEs. The aim of this study was to examine whether there is a relationship between serum AGE-ApoB and AGEs in arterial tissue of older normolipidemic nondiabetic patients with occlusive atherosclerotic disease, compared with age-matched and younger asymptomatic persons. MATERIALS AND METHODS: Serum AGE-ApoB was measured by ELISA in 21 cardiac bypass patients. Furthermore, an AGE-specific monoclonal antibody, and polyclonal antibodies against anti-AGE-receptor (anti-AGE-R) 1 and 2 were used to explore the localization and distribution of AGEs and AGE-R immunoreactivity (IR) in arterial segments excised from these patients. RESULTS: Serum AGE-ApoB levels were significantly elevated in the asymptomatic, older population, compared with those in young healthy persons (259 +/- 24 versus 180 +/- 21 AGE U/mg of ApoB, p < 0.01). Higher AGE-ApoB levels were observed in those patients with atherosclerosis (329 +/- 23 versus 259 +/- 24 AGE U/mg ApoB, p < 0.05). Comparisons of tissue AGE-collagen with serum AGE-ApoB levels showed a significant correlation (r = 0.707, p < 0.01). In early lesions, AGE-IR occurred mostly extracellularly. In fatty streaks and dense, cellular atheromatous lesions, AGE-IR was visible within lipid-containing smooth muscle cells and macrophages, while in late-stage, acellular plaques, AGE-IR occurred mostly extracellularly. AGE-R1 and -R2 were observed on vascular endothelial and smooth-muscle cells and on infiltrating mononuclear cells in the early-stage lesions, whereas in dense, late-stage plaques, they colocalized mostly with lipid-laden macrophages. On tissue sections, scoring of AGE-immunofluorescence correlated with tissue AGE and plasma AGE-ApoB. CONCLUSIONS: (1) The correlation between arterial tissue AGEs and circulating AGE-ApoB suggests a causal link between AGE modification of lipoproteins and atherosclerosis. AGE-specific receptors may contribute to this process. (2) Serum AGE-ApoB may serve to predict atherosclerosis in asymptomatic patients.
Adult↗
Molecular characterization of a mouse genomic element mobilized by advanced glycation endproduct modified-DNA (AGE-DNA).
BACKGROUND: DNA modified by advanced glycation endproducts (AGEs) undergoes a high frequency of insertional mutagenesis. In mouse lymphoid cells, these mutations are due in part to the transposition of host genomic elements that contain a DNA region homologous to the Alu family of repetitive elements. One particular 853 bp insertion, designated INS-1, was identified previously as a DNA element common to plasmids recovered from multiple, independent lymphoid cell transfections. MATERIALS AND METHODS: To characterize the genomic origin of this element, we used a 281-bp region of non-Alu-containing INS-1 sequence, designated. CORE, as a probe in Southern hybridization and for screening a bacteriophage mouse genomic DNA library. The resultant clones were sequenced and localized within the mouse genome. RESULTS: Two distinct genomic clones of 15 kB and 17 kB in size were isolated. A 522-bp unique region common to INS-1 and corresponding to the CORE sequence was identified in each clone. In both cases, CORE was found to be surrounded by repetitive DNA sequences: a 339-bp MT repeat at the 5' end, and a 150-bp B1 repeat at the 3' end. The CORE sequence was localized to mouse chromosome 1. CONCLUSIONS: These studies revealed that the CORE region of INS is present in low copy number but is associated with known repetitive DNA elements. The presence of these repetitive elements may facilitate the transposition of CORE by recombination or other, more complex rearrangement events, and explain in part the origin of AGE-induced insertional mutations.
Animals↗
An essential regulatory role for macrophage migration inhibitory factor in T-cell activation.
The protein known as macrophage migration inhibitory factor (MIF) was one of the first cytokines to be discovered and was described 30 years ago to be a T-cell-derived factor that inhibited the random migration of macrophages in vitro. A much broader role for MIF has emerged recently as a result of studies that have demonstrated it to be released from the anterior pituitary gland in vivo. MIF also is the first protein that has been identified to be secreted from monocytes/macrophages upon glucocorticoid stimulation. Once released, MIF acts to "override" or counter-regulate the suppressive effects of glucocorticoids on macrophage cytokine production. We report herein that MIF plays an important regulatory role in the activation of T cells induced by mitogenic or antigenic stimuli. Activated T cells produce MIF and neutralizing anti-MIF antibodies inhibit T-cell proliferation and interleukin 2 production in vitro, and suppress antigen-driven T-cell activation and antibody production in vivo. T cells also release MIF in response to glucocorticoid stimulation and MIF acts to override glucocorticoid inhibition of T-cell proliferation and interleukin 2 and interferon gamma production. These studies indicate that MIF acts in concert with glucocorticoids to control T-cell activation and assign a previously unsuspected but critical role for MIF in antigen-specific immune responses.
Animals↗
An agent cleaving glucose-derived protein crosslinks in vitro and in vivo.
Glucose and other reducing sugars react with proteins by a nonenzymatic, post-translational modification process called nonenzymatic glycosylation or glycation. The sugar-derived carbonyl group adds to a free amine, forming a reversible adduct which over time rearranges to produce a class of products termed advanced-glycation end-products (AGEs). These remain irreversibly bound to macromolecules and can covalently crosslink proximate amino groups. The formation of AGEs on long-lived connective tissue and matrix components accounts largely for the increase in collagen crosslinking that accompanies normal ageing and which occurs at an accelerated rate in diabetes. AGEs can activate cellular receptors and initiate a variety of pathophysiological responses. They modify an appreciable fraction of circulating low-density lipoproteins preventing uptake of these particles by their high-affinity tissue receptors. Advanced glycation has also been implicated in the pathology of Alzheimer's disease. Because AGEs may form by a pathway involving reactive alpha-dicarbonyl intermediates, we investigated a potential pharmacological strategy for selectively cleaving the resultant glucose-derived protein crosslinks. We now describe a prototypic AGE crosslink 'breaker', N-phenacylthiazolium bromide (PTB), which reacts with and cleaves covalent, AGE-derived protein crosslinks. The ability of PTB to break AGE crosslinks in vivo points to the importance of an alpha-dicarbonyl intermediate in the advanced glycation pathway and offers a potential therapeutic approach for the removal of established AGE crosslinks.
Amyloid beta-Peptides↗
Crystal structure at 2.6-A resolution of human macrophage migration inhibitory factor.
Macrophage migration inhibitory factor (MIF) was the first cytokine to be described, but for 30 years its role in the immune response remained enigmatic. In recent studies, MIF has been found to be a novel pituitary hormone and the first protein identified to be released from immune cells on glucocorticoid stimulation. Once secreted, MIF counterregulates the immunosuppressive effects of steroids and thus acts as a critical component of the immune system to control both local and systemic immune responses. We report herein the x-ray crystal structure of human MIF to 2.6 angstrom resolution. The protein is a trimer of identical subunits. Each monomer contains two antiparallel alpha-helices that pack against a four-stranded beta-sheet. The monomer has an additional two beta-strands that interact with the beta-sheets of adjacent subunits to form the interface between monomers. The three beta-sheets are arranged to form a barrel containing a solvent-accessible channel that runs through the center of the protein along a molecular 3-fold axis. Electrostatic potential maps reveal that the channel has a positive potential, suggesting that it binds negatively charged molecules. The elucidated structure for MIF is unique among cytokines or hormonal mediators, and suggests that this counterregulator of glucocorticoid action participates in novel ligand-receptor interactions.
Amino Acid Sequence↗