MIF as a disease target: ISO-1 as a proof-of-concept therapeutic. Future Med Chem. 2011;3:45-63. [PMID: 21428825 DOI: 10.4155/fmc.10.281]

The Role of Inflammatory Mediators in the Pathogenesis of Alzheimer's Disease

Alzheimer's disease (AD), a neurodegenerative disorder associated with advanced age, is the most common cause of dementia globally. AD is characterised by cognitive dysfunction, deposition of amyloid plaques, neurofibrillary tangles and neuro-inflammation. Inflammation of the brain is a key pathological hallmark of AD. Thus, clinical and immunopathological evidence of AD could be potentially supported by inflammatory mediators, including cytokines, chemokines, the complement system, acute phase proteins and oxidative mediators. In particular, oxidative mediators may actively contribute to the progression of AD and on-going inflammation in the brain. This review provides an overview of the functions and activities of inflammatory mediators in AD. An improved understanding of inflammatory processes and their role in AD is needed to improve therapeutic research aims in the field of AD and similar diseases.

Macrophage migration inhibitory factor: a key cytokine and therapeutic target in colon cancer

Macrophage migration inhibitory factor (MIF) was one of the first cytokines to be discovered, over 40 years ago. Since that time a burgeoning interest has developed in the role that MIF plays in both the regulation of normal physiology and the response to pathology. MIF is a pleotropic cytokine that functions to promote inflammation, drive cellular proliferation, inhibit apoptosis and regulate the migration and activation state of immune cells. These functions are particularly relevant for the development of cancer and it is notable that various solid tumours over express MIF. This includes tumours of the gastrointestinal tract and MIF appears to play a particularly prominent role in the development and progression of colonic adenocarcinoma. Here we review the role that MIF plays in colonic carcinogenesis through the promotion of colonic inflammation, as well as the progression of primary and metastatic colon cancer. The recent development of various antagonists and antibodies that inhibit MIF activity indicates that we may soon be able to classify MIF as a therapeutic target in colon cancer patients.

Inhibition of macrophage migration inhibitory factor reduces diabetic nephropathy in type II diabetes mice

Macrophage migration inhibitory factor (MIF) plays a critical role in inflammation and is elevated in diabetic kidney. However, whether MIF plays a causative role in diabetic nephropathy (DN) remains unclear. In the present study, we have demonstrated that after treatment of 8-week-old diabetic db/db and nondiabetic db/m mice with the MIF inhibitor ISO-1 (20 mg/kg) for 8 weeks, there was a significant decrease in blood glucose, albuminuria, extracellular matrix accumulation, epithelial-mesenchymal transition (EMT), and macrophage activation in the kidney of db/db mice. Incubation of macrophages with MIF induced the production of proinflammatory cytokines, including interleukin (IL) 6, IL-1β, tumor necrosis factor α (TNF-α). The conditioned media (CM) of MIF-activated macrophages and TNF-α induced by MIF caused podocyte damage. Moreover, CM from MIF-activated macrophages induced EMT of renal tubular cells, and this effect was blocked by ISO-1. Thus, MIF inhibition may be a potential therapeutic strategy for DN. This effect may be attributable to its inhibitory effect on macrophage activation in the diabetic kidney.

Macrophage migration inhibitory factor promotes cyst growth in polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by renal cyst formation, inflammation, and fibrosis. Macrophages infiltrate cystic kidneys, but the role of these and other inflammatory factors in disease progression are poorly understood. Here, we identified macrophage migration inhibitory factor (MIF) as an important regulator of cyst growth in ADPKD. MIF was upregulated in cyst-lining epithelial cells in polycystin-1-deficient murine kidneys and accumulated in cyst fluid of human ADPKD kidneys. MIF promoted cystic epithelial cell proliferation by activating ERK, mTOR, and Rb/E2F pathways and by increasing glucose uptake and ATP production, which inhibited AMP-activated protein kinase signaling. MIF also regulated cystic renal epithelial cell apoptosis through p53-dependent signaling. In polycystin-1-deficient mice, MIF was required for recruitment and retention of renal macrophages, which promoted cyst expansion, and Mif deletion or pharmacologic inhibition delayed cyst growth in multiple murine ADPKD models. MIF-dependent macrophage recruitment was associated with upregulation of monocyte chemotactic protein 1 (MCP-1) and inflammatory cytokine TNF-α. TNF-α induced MIF expression, and MIF subsequently exacerbated TNF-α expression in renal epithelial cells, suggesting a positive feedback loop between TNF-α and MIF during cyst development. Our study indicates MIF is a central and upstream regulator of ADPKD pathogenesis and provides a rationale for further exploration of MIF as a therapeutic target for ADPKD.

Multiple binding modes of isothiocyanates that inhibit macrophage migration inhibitory factor

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that has roles in the innate immune response, and also contributes to inflammatory disease. While the biological properties of MIF are closely linked to protein-protein interactions, MIF also has tautomerase activity. Inhibition of this activity interferes with the interaction of MIF with protein partners e.g. the CD74 receptor, and tautomerase inhibitors show promise in disease models including multiple sclerosis and colitis. Isothiocyanates inhibit MIF tautomerase activity via covalent modification of the N-terminal proline. We systematically explored variants of benzyl and phenethyl isothiocyanates, to define determinants of inhibition. In particular, substitution with hydroxyl, chloro, fluoro and trifluoro moieties at the para and meta positions were evaluated. In assays on treated cells and recombinant protein, the IC50 varied from 250 nM to >100 μM. X-ray crystal structures of selected complexes revealed that two binding modes are accessed by some compounds, perhaps owing to strain in short linkers between the isothiocyanate and aromatic ring. The variety of binding modes confirms the existence of two subsites for inhibitors and establishes a platform for the development of potent inhibitors of MIF that only need to target one of these subsites.

Pharmacological inhibition of MIF interferes with trophoblast cell migration and invasiveness

INTRODUCTION

Macrophage migration inhibitory factor (MIF) is expressed by villous and extravillous cytotrophoblast. This study was aimed to investigate functional relevance of MIF for human trophoblast.

METHODS

MIF mRNA and protein were documented in cytotrophoblast (CT) and extravillous trophoblast cell line HTR-8/SVneo by RT-PCR, Western blot (WB), and immunocytochemistry. Recombinant human MIF (rhMIF), or its specific inhibitor (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1) were used in Wound healing migration and Matrigel invasion tests. Potential effectors, integrin subunits and matrix metalloproteinases (MMP) were studied using WB and gelatin zymography, respectively.

RESULTS

Blocking endogenous MIF by ISO-1 decreased HTR-8/SVneo cell migration dose dependently, most significantly with 200 μg/ml to 65% of control. Supplementation with rhMIF induced a significant stimulation to 129% of control with 200 ng/ml. In CT cell invasion test, ISO-1 at 200 μg/ml reduced invasion to 59% of control, while rhMIF (200 ng/ml) induced stimulation to 159% of control. In HTR-8/SVneo cells, invasion was significantly inhibited by ISO-1 to 40%, and increased to 150% of control by rhMIF (200 ng/ml). Integrin α1 was reduced by ISO-1 in both cell types, while integrins α5 and β1 were not changed. Addition of rhMIF increased integrin α1. In the presence of ISO-1, levels of MMP-2 and MMP-9 were reduced in CT and HTR-8/SVneo, while rhMIF stimulated MMP-2 in CT and MMP-9 in HTR-8/SVneo cells.

CONCLUSION

Reported findings provide the first insight into the cellular effects of MIF in human trophoblast, which acts to promote cell migration and invasion.

Macrophage migration inhibitory factor triggers chemotaxis of CD74+CXCR2+ NKT cells in chemically induced IFN-γ-mediated skin inflammation

IFN-γ mediates chemically induced skin inflammation; however, the mechanism by which IFN-γ-producing cells are recruited to the sites of inflammation remains undefined. Secretion of macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, from damaged cells may promote immune cell recruitment. We hypothesized that MIF triggers an initial step in the chemotaxis of IFN-γ-producing cells in chemically induced skin inflammation. Using acute and chronic models of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced skin inflammation in mouse ears, MIF expression was examined, and its role in this process was investigated pharmacologically. The cell populations targeted by MIF, their receptor expression patterns, and the effects of MIF on cell migration were examined. TPA directly caused cytotoxicity accompanied by MIF release in mouse ear epidermal keratinocytes, as well as in human keratinocytic HaCaT cells. Treatment with the MIF antagonist (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester considerably attenuated TPA-induced ear swelling, leukocyte infiltration, epidermal cell proliferation, and dermal angiogenesis. Inhibition of MIF greatly diminished the dermal infiltration of IFN-γ(+) NKT cells, whereas the addition of exogenous TPA and MIF to NKT cells promoted their IFN-γ production and migration, respectively. MIF specifically triggered the chemotaxis of NKT cells via CD74 and CXCR2, and the resulting depletion of NKT cells abolished TPA-induced skin inflammation. In TPA-induced skin inflammation, MIF is released from damaged keratinocytes and then triggers the chemotaxis of CD74(+)CXCR2(+) NKT cells for IFN-γ production.

Blocking macrophage migration inhibitory factor activity alleviates mouse acute otitis media in vivo

This study was to investigate the role of macrophage migration inhibitory factor (MIF) in mouse acute otitis media (AOM), we hypothesize that blocking MIF activity will relieve mouse AOM. A mouse AOM model was constructed by injecting lipopolysaccharide (LPS) into the middle ear of C57BL/6 mice through the tympanic membrane (TM). MIF levels were measured by real-time PCR (RT-PCR) and ELISA after LPS application. Normal or AOM mice were given PBS or ISO-1 (MIF antagonist) every day for 10 days and the hearing levels were determined by measuring auditory brainstem response (ABR) threshold. After the ABR test finished, H&E staining was conducted and the inflammation was also measured by detecting interleukin (IL)-1β, tumor necrosis factor (TNF)-α and vascular endothelial growth factor (VEGF) levels with RT-PCR and ELISA. TLR-4 expression was determined by western blotting and NF-κB activation was determined by electrophoretic mobility shift assays. Compared with the normal control, MIF levels in the middle ear of LPS-induced AOM mice were significant increased. The ABR results showed that mean ABR thresholds in ISO-1 treated AOM mice were significantly reduced compared with PBS treated AOM mice since day 7, indicating that ISO-1 treatment potentially improved the hearing levels of AOM mice. H&E staining showed that ISO-1 treatment could reduce the mucosal thickness of AOM mice. In ISO-1 treated mice, TLR-4 expression and levels of IL-1β, TNF-α and VEGF were significantly lower compared with PBS treated AOM mice. ISO-1 treatment also significantly inhibited NF-κB activation in AOM mice compared with PBS treated AOM mice. These results suggested that blocking the activity of MIF by ISO-1 could reduce the inflammation in AOM mice in which process TLR-4 and NF-κB were involved. The reduction in MIF activity is conducive to alleviate mouse AOM, which may serve as a potential therapeutic target for the treatment of AOM.

The Potential Role of Chemokines in Alzheimer's Disease Pathogenesis

Alzheimer's disease (AD) is a neurodegenerative disorder and leading cause of dementia, which begins with impaired memory. The neuropathological hallmarks of AD include destructive alterations of neurons by neurofibrillary tangles, neuritic amyloid plaques, and neuroinflammatory process in the brain. Chemokines have a major role in inflammatory cell attraction and glial cell activation and/or modulation in the central nervous system. Moreover, the clinical and immunopathological evidence could show dual key role of chemokines in their pro- and anti-inflammatory properties in AD. However, their effects in neurodegeneration and/or neuroprotection remain an area of investigation. This review article provides an overview of characteristic, cellular source and activity of chemokines, and their roles in neuronal glial cell interaction in AD.

ISO-66, a novel inhibitor of macrophage migration, shows efficacy in melanoma and colon cancer models

Macrophage migration inhibitory factor (MIF) is a pleiotropic pro-inflammatory cytokine, which possesses a contributing role in cancer progression and metastasis and, thus, is now considered a promising anticancer drug target. Many MIF-inactivating strategies have proven successful in delaying cancer growth. Here, we report on the synthesis of ISO-66, a novel, highly stable, small-molecule MIF inhibitor, an analog of ISO-1 with improved characteristics. The MIF:ISO-66 co-crystal structure demonstrated that ISO-66 ligates the tautomerase active site of MIF, which has previously been shown to play an important role in its biological functions. In vitro, ISO-66 enhanced specific and non-specific anticancer immune responses, whereas prolonged administration of ISO-66 in mice with established syngeneic melanoma or colon cancer was non-toxic and resulted in a significant decrease in tumor burden. Subsequent ex vivo analysis of mouse splenocytes revealed that the observed decrease in tumor growth rates was likely mediated by the selective in vivo expansion of antitumor-reactive effector cells induced by ISO-66. Compared to other MIF-inactivating strategies employed in vivo, the anticancer activity of ISO-66 is demonstrated to be of equal or better efficacy. Our findings suggest that targeting MIF, via highly specific and stable compounds, such as ISO-66, may be effective for cancer treatment and stimulation of anticancer immune responses.

Targeting distinct tautomerase sites of D-DT and MIF with a single molecule for inhibition of neutrophil lung recruitment

We report a new inflammatory activity for extracellular d-dopachrome tautomerase (D-DT), the recruitment of neutrophils to the lung on D-DT intratracheal installation of C57BL/6J mice with an EC50 of 5.6 μg. We also find that D-DT and macrophage migration inhibitory factor (MIF) have additive effects in neutrophil recruitment. Although the tautomerase site of D-DT and its homologue MIF are biophysically very different, 4-iodo-6-phenylpyrimidine (4-IPP) forms a covalent bond with Pro-1 of both proteins, resulting in a 6-phenylpyrimidine (6-PP) adduct. Recruitment of neutrophils to the lung for the 6-PP adducts of D-DT and MIF are reduced by ∼ 50% relative to the apo proteins, demonstrating that an unmodified Pro-1 is important for this activity, but there is no cooperativity in inhibition of the proteins together. The differences in the binding mode of the 6-PP adduct for D-DT was determined by crystallographic studies at 1.13 Å resolution and compared to the structure of the MIF-6-PP complex. There are major differences in the location of the 6-PP adduct to the D-DT and MIF active sites that provide insight into the lack of cooperativity by 4-IPP and into tuning the properties of the covalent inhibitors of D-DT and MIF that are necessary for the development of therapeutic small molecules against neutrophil damage from lung infections such as Pseudomonas aeruginosa in cystic fibrosis and immunocompromised patients.

Novel inhibitors of macrophage migration inhibitory factor prevent cytokine-induced beta cell death

Macrophage migration inhibitory factor is a multifunctional cytokine involved in the regulation of immune processes and also in apoptosis induction. Elevated MIF expression is detrimental for insulin-producing beta cells and MIF inhibition protected beta cells from several cytotoxic insults such as inflammatory cytokines, high fatty acids or high glucose concentrations. Therefore, the aim of this study was to investigate two newly synthesized small molecule MIF inhibitors (K664-1 and K647-1) and to compare them with previously established effects of the prototypical MIF inhibitor, ISO-1. Our results indicate that K664-1 and K647-1 are 160- and 40-fold more effective in inhibition of MIF׳s tautomerase activity than ISO-1. Also, new inhibitors confer beta cell protection from cytokine-triggered apoptosis at significantly lower concentrations than ISO-1. Although all three MIF inhibitors inhibit caspase 3 activity, K664-1 and K647-1 suppress pro-apoptotic BAX protein expression and up-regulate anti-apoptotic Bcl-2 mRNA. Finally, all three MIF inhibitors operate through blockade of nitric oxide production stimulated by cytokines. In conclusion, two novel MIF inhibitors are more potent than ISO-1 and operate through inhibition of the mitochondria-related apoptotic pathway. We propose that these compounds represent a unique class of anti-MIF antagonists that should be further tested for therapeutic use.

Migration inhibitory factor enhances inflammation via CD74 in cartilage end plates with Modic type 1 changes on MRI

BACKGROUND

Type 1 Modic changes are characterized by edema, vascularization, and inflammation, which lead to intervertebral disc degeneration. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine closely related to the inflammatory cytokines detected in degenerative intervertebral disc tissues. However, the existence and role of MIF and its receptor CD74 in intervertebral disc degeneration have not been elucidated.

QUESTIONS/PURPOSES

We asked whether (1) MIF and its receptor CD74 are expressed in cartilage end plates with Type 1 Modic changes, (2) MIF is associated with cartilage end plate degeneration, (3) the MIF antagonist (S, R)-3(4-hydroxyphenyl)-4, 5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1) suppresses MIF-induced inflammatory cytokine release, and (4) inflammatory cytokines are released by cartilage end plate chondrocytes via CD74 by activating the CD74 antibody (CD74Ab).

METHODS

We examined MIF and CD74 expression by human cartilage end plate chondrocytes and tissues with Type 1 Modic changes from eight patients using immunocytofluorescence and immunohistochemistry. MIF production by the chondrocytes was assessed by ELISA and PCR. We compared cytokine release by chondrocytes treated with MIF in the presence or absence of exogenous ISO-1 by ELISA. Cytokine release by chondrocytes after treatment with CD74Ab was determined by ELISA.

RESULTS

MIF was expressed in degenerated human cartilage end plate tissues and chondrocytes. Lipopolysaccharide and tumor necrosis factor α (TNF-α) upregulated MIF expression and increased MIF secretion in chondrocytes in a dose-dependent manner. MIF increased the secretion of IL-6, IL-8, and prostaglandin E2 (PGE2) in a dose-dependent manner. ISO-1 reduced the secretion of IL-6, IL-8, and PGE2. CD74Ab activated CD74 and induced release of inflammatory cytokines.

CONCLUSIONS

Chondrocytes in cartilage end plate with Type 1 Modic changes express MIF and its receptor CD74. MIF might promote the inflammatory response through CD74. MIF-induced cytokine release appears to be suppressed by ISO-1, and CD74Ab could induce cytokine release.

CLINICAL RELEVANCE

The MIF/CD74 pathway may represent a crucial target for treating disc degeneration since inhibiting the function of MIF with its antagonist ISO-1 can reduce MIF-induced inflammation and exert potent therapeutic effects.

Virtual Screening of Some Active Human Macrophage Migration Inhibitory Factor Antagonists

Macrophage migration inhibitory factor (MIF) is an autocrine- and paracrine-acting cytokine that is involved in several inflammatory, autoimmune, infectious, and oncogenic diseases. Clinical data have shown that inhibition of MIF, especially its tautomerase activity, with small compounds has been beneficial in some disease models. A virtual screening (VS) experiment is conducted for searching some active compounds to inhibit the tautomerase activity of MIF from the ZINC database. By using an x-ray-determined structure OXIM-11 as the query and an in-house developed two-dimensional scaffold comparing method designated as Sfilter, we have screened out some 1500 compounds for ranking by our previously published docking method ADDock. After further ranking by ADDock on 119 compounds screened, we have decided to choose 17 of them for measuring their inhibitory activity IC50 against the MIF tautomerase experimentally. The IC50's are measured using both human monocytic THP-1 cell lysate and purified recombinant human MIF protein. We have found that the IC50's measured for three searched compounds (namely, ZINC02693801, ZINC00141102, and ZINC12368346) are better than that determined for ISO-1, a known MIF tautomerase inhibitor and standard used throughout our VS experiment. Moreover, the scaffolds of most of our active compounds searched are also quite different from those searched and published by others previously.

MIF: mood improving/inhibiting factor?

Although major depressive disorder imposes a serious public health burden and affects nearly one in six individuals in developed countries over their lifetimes, there is still no consensus on its pathophysiology. Inflammation and cytokines have emerged as a promising new avenue in depression research, and, in particular, macrophage migration inhibitory factor (MIF) has been shown to be significant in depression physiology. In this review we summarize current research on MIF and depression. We highlight the arguments for MIF as a pro- and antidepressant species and discuss the potential implications for therapeutics.

Human single-chain variable fragment antibody inhibits macrophage migration inhibitory factor tautomerase activity

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine, secreted from a variety of immune cells, that regulates innate and adaptive immune responses. Elevation of MIF levels in plasma correlates with the severity of inflammatory diseases in humans. Inhibition of MIF or its tautomerase activity ameliorates disease severity by reducing inflammatory responses. In this study, the human single-chain variable fragment (HuScFv) antibody specific to MIF was selected from the human antibody phage display library by using purified recombinant full-length human MIF (rMIF) as the target antigen. Monoclonal HuScFv was produced from phage-transformed bacteria and tested for their binding activities to rMIF by indirect enzyme-linked immunosorbent assay as well as to native MIF by western blot analysis and immunofluorescence assay. The HuScFv with highest binding signal to rMIF also inhibited the tautomerase activities of both rMIF and native MIF in human monoblastic leukemia (U937) cells in a dose-dependent manner. Mimotope searching and molecular docking concordantly demonstrated that the HuScFv interacted with Lys32 and Ile64 in the MIF tautomerase active site. To the best of our knowledge, this is the first study to focus on MIF-specific fully-human antibody fragment with a tautomerase-inhibitory effect that has potential to be developed as anti-inflammatory biomolecules for human use.

The role of MIF in type 1 and type 2 diabetes mellitus

Autoimmunity and chronic low-grade inflammation are hallmarks of diabetes mellitus type one (T1DM) and type two (T2DM), respectively. Both processes are orchestrated by inflammatory cytokines, including the macrophage migration inhibitory factor (MIF). To date, MIF has been implicated in both types of diabetes; therefore, understanding the role of MIF could affect our understanding of the autoimmune or inflammatory responses that influence diabetic pathology. This review highlights our current knowledge about the involvement of MIF in both types of diabetes in the clinical environment and in experimental disease models.

P115 promotes growth of gastric cancer through interaction with macrophage migration inhibitory factor

AIM: To investigate the role of P115 in the proliferation of gastric cancer cells and the mechanism involved.

METHODS: The RNA and protein level of P115 and macrophage migration inhibitory factor (MIF) in gastric cancer and normal gastric tissue/cells were measured and the effect of P115 on cell proliferation was assessed. The role of P115 in cell cycle checkpoints was investigated and the related proteins and signaling pathways, such as cyclin D1, Mcm2, p53, PCNA as well as the MAPK signaling pathway were determined. The interaction between P115 and MIF and the effect of P115 on MIF secretion were examined. The data were analyzed via one-way ANOVA comparisons between groups and P < 0.05 was considered significant.

RESULTS: P115 and MIF were both specifically expressed in gastric cancer tissues compared with normal gastric mucosa (both P < 0.01). The mRNA and protein levels of P115 and MIF in gastric cancer cell lines MKN-28 and BGC-823 were higher than in the human gastric epithelial cell line GES-1 (both P < 0.01). In MKN-28 and BGC-823 cell lines, P115 promoted cell proliferation and G₀-G₁ to S phase transition. In addition, several cell cycle-related regulators, including cyclin D1, Mcm2, PCNA, pERK1/2 and p53 were up-regulated by P115. Furthermore, the interaction between P115 and MIF was confirmed by co-immunoprecipitation assay. ELISA showed that P115 stimulated the secretion of MIF into the culture supernatant (P < 0.01) and the compensative expression of MIF in cells was observed by Western blotting.

CONCLUSION: P115 promotes proliferation of gastric cancer cells through an interaction with MIF.

Novel arylazoarylmethane as potential inhibitor of macrophage migration inhibitory factor

Macrophage migration inhibitory factor (MIF), a cytokine involved in the pathogenesis of sepsis, diabetes, asthma, arthritis, and cancer, has an enzymatic active site that has proven to be an effective target for small molecule-based inhibitors. Herein, we describe the synthesis of a novel arylazoarylmethane compound (3) from a known arylhydrazone MIF inhibitor (2). This new compound has improved stability and in vivo biological activity.

Macrophage migration inhibitory factor inhibition is deleterious for high-fat diet-induced cardiac dysfunction

Aims

Development of metabolic syndrome is associated with impaired cardiac performance, mitochondrial dysfunction and pro-inflammatory cytokine increase, such as the macrophage migration inhibitory factor MIF. Depending on conditions, MIF may exert both beneficial and deleterious effects on the myocardium. Therefore, we tested whether pharmacological inhibition of MIF prevented or worsened metabolic syndrome-induced myocardial dysfunction.

Methods and Results

C57BL/6J mice were fed for ten weeks with 60% fat-enriched diet (HFD) or normal diet (ND). MIF inhibition was obtained by injecting mice twice a week with ISO-1, for three consecutive weeks. Then, triglycerides, cholesterol, fat mass, glucose intolerance, insulin resistance, ex vivo cardiac contractility, animal energetic substrate utilization assessed by indirect calorimetry and mitochondrial respiration and biogenesis were evaluated. HFD led to fat mass increase, dyslipidemia, glucose intolerance and insulin resistance. ISO-1 did not alter these parameters. However, MIF inhibition was responsible for HFD-induced cardiac dysfunction worsening. Mouse capacity to increase oxygen consumption in response to exercise was reduced in HFD compared to ND, and further diminished in ISO-1-treated HFD group. Mitochondrial respiration was reduced in HFD mice, treated or not with ISO-1. Compared to ND, mitochondrial biogenesis signaling was upregulated in the HFD as demonstrated by mitochondrial DNA amount and PGC-1α expression. However, this increase in biogenesis was blocked by ISO-1 treatment.

Conclusion

MIF inhibition achieved by ISO-1 was responsible for a reduction in HFD-induced mitochondrial biogenesis signaling that could explain majored cardiac dysfunction observed in HFD mice treated with MIF inhibitor.

Macrophage migration inhibitory factor: a potential marker for cancer diagnosis and therapy

Macrophage migration inhibitory factor (MIF) is a pluripotent cytokine which plays roles in inflammation, immune responses and cancer development. It assists macrophages in carrying out functions like phagocytosis, adherence and motility. Of late, MIF is implicated in almost all stages of neoplasia and expression is a feature of most types of cancer. The presence of MIF in almost all tumors and all stages of cancer makes it an interesting candidate for cancer therapy. This review explores the roles of MIF in neoplasia.

Capillary and arteriolar pericytes attract innate leukocytes exiting through venules and 'instruct' them with pattern-recognition and motility programs

Coordinated navigation within tissues is essential for cells of the innate immune system to reach the sites of inflammatory processes, but the signals involved are incompletely understood. Here we demonstrate that NG2(+) pericytes controlled the pattern and efficacy of the interstitial migration of leukocytes in vivo. In response to inflammatory mediators, pericytes upregulated expression of the adhesion molecule ICAM-1 and released the chemoattractant MIF. Arteriolar and capillary pericytes attracted and interacted with myeloid leukocytes after extravasating from postcapillary venules, 'instructing' them with pattern-recognition and motility programs. Inhibition of MIF neutralized the migratory cues provided to myeloid leukocytes by NG2(+) pericytes. Hence, our results identify a previously unknown role for NG2(+) pericytes as an active component of innate immune responses, which supports the immunosurveillance and effector function of extravasated neutrophils and macrophages.

Macrophage migration inhibitory factor covalently complexed with phenethyl isothiocyanate

Macrophage migration inhibitory factor is irreversibly inhibited via covalent modification by phenethyl isothiocyanate, a naturally occurring compound with anti-inflammatory and anticancer properties. The structure of the modified protein obtained from X-ray diffraction data to 1.64 Å resolution is presented. The inhibitor sits within a deep hydrophobic pocket between subunits of the homotrimer and is highly ordered. The secondary structure of macrophage migratory inhibitory factor is unchanged by this modification, but there are significant rearrangements, including of the side-chain position of Tyr37 and the main chain of residues 31-34. These changes may explain the decreased binding of the modified protein to the receptor CD74. Together with the pocket, the areas of conformational change define specific targets for the design of more selective and potent inhibitors as potential therapeutics.

Macrophage migration inhibitory factor inhibits the migration of cartilage end plate-derived stem cells by reacting with CD74

BACKGROUND

Macrophage migration inhibitory factor (MIF) is a multifunctional cytokine that regulates inflammatory reactions and the pathophysiology of many inflammatory diseases. Intervertebral disc (IVD) degeneration is characterized by an inflammatory reaction, but the potential role of MIF in IVD degeneration has not been determined. Recent studies have shown that MIF and its receptor, CD74, are involved in regulating the migration of human mesenchymal stem cells (MSCs); Thus, MIF might impair the ability of mesenchymal stem cells (MSCs) to home to injured tissues. Our previous studies indicated that cartilage endplate (CEP)-derived stem cells (CESCs) as a type of MSCs exist in human degenerate IVDs. Here, we investigate the role of MIF in regulating the migration of CESCs.

METHODS AND FINDINGS

CESCs were isolated and identified. We have shown that MIF was distributed in human degenerate IVD tissues and was subject to regulation by the pro-inflammatory cytokine TNF-α. Furthermore, in vitro cell migration assays revealed that nucleus pulposus (NP) cells inhibited the migration of CESCs in a number-dependent manner, and ELISA assays revealed that the amount of MIF in conditioned medium (CM) was significantly increased as a function of increasing cell number. Additionally, recombinant human MIF (r-MIF) inhibited the migration of CESCs in a dose-dependent manner. CESCs migration was restored when an antagonist of MIF, (S, R)-3(4-hydroxyphenyl)-4, 5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1), was added. Finally, a CD74 activating antibody (CD74Ab) was used to examine the effect of CD74 on CESCs motility and inhibited the migration of CESCs in a dose-dependent manner.

CONCLUSIONS

We have identified and characterized a novel regulatory mechanism governing cell migration during IVD degeneration. The results will benefit understanding of another possible mechanism for IVD degeneration, and might provide a new method to repair degenerate IVD by enhancing CESCs migration to degenerated NP tissues to exert their regenerative effects.

Novel anti-inflammatory activity of epoxyazadiradione against macrophage migration inhibitory factor: inhibition of tautomerase and proinflammatory activities of macrophage migration inhibitory factor

Macrophage migration inhibitory factor (MIF) is responsible for proinflammatory reactions in various infectious and non-infectious diseases. We have investigated the mechanism of anti-inflammatory activity of epoxyazadiradione, a limonoid purified from neem (Azadirachta indica) fruits, against MIF. Epoxyazadiradione inhibited the tautomerase activity of MIF of both human (huMIF) and malaria parasites (Plasmodium falciparum (PfMIF) and Plasmodium yoelii (PyMIF)) non-competitively in a reversible fashion (K(i), 2.11-5.23 μm). Epoxyazadiradione also significantly inhibited MIF (huMIF, PyMIF, and PfMIF)-mediated proinflammatory activities in RAW 264.7 cells. It prevented MIF-induced macrophage chemotactic migration, NF-κB translocation to the nucleus, up-regulation of inducible nitric-oxide synthase, and nitric oxide production in RAW 264.7 cells. Epoxyazadiradione not only exhibited anti-inflammatory activity in vitro but also in vivo. We tested the anti-inflammatory activity of epoxyazadiradione in vivo after co-administering LPS and MIF in mice to mimic the disease state of sepsis or bacterial infection. Epoxyazadiradione prevented the release of proinflammatory cytokines such as IL-1α, IL-1β, IL-6, and TNF-α when LPS and PyMIF were co-administered to BALB/c mice. The molecular basis of interaction of epoxyazadiradione with MIFs was explored with the help of computational chemistry tools and a biological knowledgebase. Docking simulation indicated that the binding was highly specific and allosteric in nature. The well known MIF inhibitor (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1) inhibited huMIF but not MIF of parasitic origin. In contrast, epoxyazadiradione inhibited both huMIF and plasmodial MIF, thus bearing an immense therapeutic potential against proinflammatory reactions induced by MIF of both malaria parasites and human.

Thyroxine is a potential endogenous antagonist of macrophage migration inhibitory factor (MIF) activity

Abnormally low plasma concentrations of thyroid hormones during sepsis often occur in the absence of thyroidal illness; however, the mechanisms involved in the "euthyroid sick syndrome" remain poorly understood. Here, we describe a previously unrecognized interaction between the thyroid hormone thyroxine (T(4)) and the proinflammatory cytokine macrophage migration inhibitory factor (MIF), together with its clinical relevance in sepsis. We found that in both patients with severe sepsis, and our rodent model, low plasma T(4) concentrations were inversely correlated with plasma MIF concentrations. The MIF molecule contains a hydrophobic pocket that is important for many of its proinflammatory activities. Binding of L-T(4) (or its hormonally inert isomer D-T(4)) significantly, and dose-dependently, inhibited the catalytic activity of this pocket. Moreover, administration of exogenous D-T(4) significantly improved survival in mice with severe sepsis. To examine the specificity of the MIFT(4) interaction, wild-type and MIF knockout mice were subjected to the carrageenan-air pouch model of inflammation and then treated with D-T(4) or vehicle. D-T(4) significantly inhibited leukocyte infiltration in wild-type mice but not in MIF knockout mice, providing evidence that in vivo T(4) may influence MIF-mediated inflammatory responses via inhibition of its hydrophobic proinflammatory pocket. These findings demonstrate a new physiological role for T(4) as a natural inhibitor of MIF proinflammatory activity. The data may also, in part, explain the low plasma T(4) concentrations in critically ill, euthyroid patients and suggest that targeting the imbalance between MIF and T(4) may be beneficial in improving outcome from sepsis.