Virtual Screening of Some Active Human Macrophage Migration Inhibitory Factor Antagonists

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

Macrophage migration inhibitory factor (MIF) is a major mediator in innate immunity and inflammation and a potential therapeutic target in multiple inflammatory, infectious and autoimmune diseases including cancer. Current therapeutic strategies for targeting MIF focus on modulating its biological activities using anti-MIF neutralizing antibodies or developing inhibitors of its tautomerase activity. Although the identity of its natural substrate remains unknown, several small molecule inhibitors have been reported to be effective inhibitors of MIF tautomerase activity in vitro. All these inhibitors were identified by rational design and structure-activity studies based on the structure of the catalytic site and/or non physiologic substrates of MIF. The lack of suitable high-throughput screening (HTS) assays has hindered the screening of chemical libraries and discovery of more diverse inhibitors. Motivated by the goal of discovering diverse classes of MIF inhibitors that modulate MIF activity specific targeting of its biochemical, conformation and quaternary structure properties, both activity based endpoint and kinetic HTS assays were developed, optimized and performed on diverse set of libraries. Using the endpoint assay, out of 15440 compounds screened, twelve novel inhibitors of MIF's catalytic activity (∼ 0.1% hit rate) with IC50s in the range of 1.5 to 15.5 µM were identified and validated. The interaction site and mechanism of action of all these inhibitors were defined using structure activity studies and a battery of biochemical and biophysical methods, including mass spectrometry, light scattering, and NMR. The effect on MIF biological activities was also examined on MIF-mediated glucocorticoid overriding and MIF-induced Akt phosphorylation. Using the kinetic-based activity assay, we screened 80,000 small molecules and identified and validated thirteen novel inhibitors of MIF catalytic activity with inhibition constant (Ki,app) values ranging from 0.5 to 13 µM. According to the structure and potency some of these molecules could be of great therapeutic potential. The MIF inhibitors emerging from these studies could be divided into four classes: 1) molecules that covalently modify the catalytic site at the N-terminal proline residue, Pro1 which could be classified into 5 groups; 2) a novel class of catalytic site inhibitors, 3) a class of trimer destabilizing inhibitors. These findings demonstrate the potential of HTS assays as attractive means to identify novel classes of MIF inhibitors as lead drug candidates and/or chemical tools for elucidating the biochemical and structural bases underlying the multifunctionality of MIF's in health and disease. Having these molecules in hand, will advance our understanding of protein-protein interactions mechanism for MIF oligomerization and may help to elucidate the role of MIF enzymatic activity in health and disease.

Macrophage migration inhibitory factor (MIF) is a proinflammatory mediator with unique tautomerase enzymatic activity; the precise function has not been clearly defined. We previously demonstrated that individual patients with cystic fibrosis (CF) who are genetically predisposed to be high MIF producers develop accelerated end-organ injury. To characterize the effects of the MIF-CATT polymorphism in patients with CF ex vivo. To investigate the role of MIF's tautomerase activity in a murine model of Pseudomonas aeruginosa infection. MIF and tumor necrosis factor (TNF)-α protein levels were assessed in plasma or peripheral blood mononuclear cell (PBMC) supernatants by ELISA. A murine pulmonary model of chronic Pseudomonas infection was used in MIF wild-type mice (mif(+/+)) and in tautomerase-null, MIF gene knockin mice (mif (P1G/P1G)). MIF protein was measured in plasma and PBMCs from 5- and 6-CATT patients with CF; LPS-induced TNF-α production from PBMCs was also assessed. The effect of a specific inhibitor of MIF-tautomerase activity, ISO-1, was investigated in PBMCs. In the murine infection model, total weight loss, differential cell counts, bacterial load, and intraacinar airspace/tissue volume were measured. MIF and TNF-α levels were increased in 6-CATT compared with 5-CATT patients with CF. LPS-induced TNF-α production from PBMCs was attenuated in the presence of ISO-1. In a murine model of Pseudomonas infection, significantly less pulmonary inflammation and bacterial load was observed in mif(P1G/P1G) compared with mif(+/+) mice. MIF-tautomerase activity may provide a novel therapeutic target in patients with chronic inflammatory diseases such as CF, particularly those patients who are genetically predisposed to produce increased levels of this cytokine.

<div>Abstract<p>Pancreatic cancer is a deadly disease that is largely resistant to immunotherapy, in part because of the accumulation of immunosuppressive cells in the tumor microenvironment (TME). Much evidence suggests that tumor-derived exosomes (TDE) contribute to the immunosuppressive activity mediated by myeloid-derived suppressor cells (MDSC) within the pancreatic cancer TME. However, the underlying mechanisms remain elusive. Herein, we report that macrophage migration inhibitory factor (MIF) in TDEs has a key role in inducing MDSC formation in pancreatic cancer. We identified MIF in both human and murine pancreatic cancer–derived exosomes. Upon specific shRNA-mediated knockdown of MIF, the ability of pancreatic cancer–derived exosomes to promote MDSC differentiation was abrogated. This phenotype was rescued by reexpression of the wild-type form of MIF rather than a tautomerase-null mutant or a thiol-protein oxidoreductase-null mutant, indicating that both MIF enzyme activity sites play a role in exosome-induced MDSC formation in pancreatic cancer. RNA sequencing data indicated that MIF tautomerase regulated the expression of genes required for MDSC differentiation, recruitment, and activation. We therefore developed a MIF tautomerase inhibitor, IPG1576. The inhibitor effectively inhibited exosome-induced MDSC differentiation <i>in vitro</i> and reduced tumor growth in an orthotopic pancreatic cancer model, which was associated with decreased numbers of MDSCs and increased infiltration of CD8<sup>+</sup> T cells in the TME. Collectively, our findings highlight a pivotal role for MIF in exosome-induced MDSC differentiation in pancreatic cancer and underscore the potential of MIF tautomerase inhibitors to reverse the immunosuppressive pancreatic cancer microenvironment, thereby augmenting anticancer immune responses.</p></div>

In a previous study, we showed that murine dendritic cells (DCs) can increase the number of neural stem/progenitor cells (NSPCs) in vitro and in vivo. In the present study, we identified macrophage migration inhibitory factor (MIF) as a novel factor that can support the proliferation and/or survival of NSPCs in vitro. MIF is secreted by DCs and NSPCs, and its function in the normal brain remains largely unknown. It was previously shown that in macrophages, MIF binds to a CD74-CD44 complex. In the present study, we observed the expression of MIF receptors in mouse ganglionic-eminence-derived neurospheres using flow cytometry in vitro. We also found CD74 expression in the ganglionic eminence of E14 mouse brains, suggesting that MIF plays a physiological role in vivo. MIF increased the number of primary and secondary neurospheres. By contrast, retrovirally expressed MIF shRNA and MIF inhibitor (ISO-1) suppressed primary and secondary neurosphere formation, as well as cell proliferation. In the neurospheres, MIF knockdown by shRNA increased caspase 3/7 activity, and MIF increased the phosphorylation of Akt, Erk, AMPK and Stat3 (Ser727), as well as expression of Hes3 and Egfr, the products of which are known to support cell survival, proliferation and/or maintenance of NSPCs. MIF also acted as a chemoattractant for NSPCs. These results show that MIF can induce NSPC proliferation and maintenance by multiple signaling pathways acting synergistically, and it may be a potential therapeutic factor, capable of activating NSPC, for the treatment of degenerative brain disorders.

Constitutively expressed by innate immune cells, the cytokine macrophage migration inhibitory factor (MIF) initiates host immune responses and drives pathogenic responses in infectious, inflammatory, and autoimmune diseases. Dendritic cells (DCs) express high levels of MIF, but the role of MIF in DC function remains poorly characterized. As migration is critical for DC immune surveillance, we investigated whether MIF promoted the migration of DCs. In classical transwell experiments, MIF-/- bone marrow-derived DCs (BMDCs) or MIF+/+ BMDCs treated with ISO-1, an inhibitor of MIF, showed markedly reduced spontaneous migration and chemotaxis. CD74-/- BMDCs that are deficient in the ligand-binding component of the cognate MIF receptor exhibited a migration defect similar to that of MIF-/- BMDCs. Adoptive transfer experiments of LPS-matured MIF+/+ and MIF-/- and of CD74+/+ and CD74-/- BMDCs injected into the hind footpads of homologous or heterologous mice showed that the autocrine and paracrine MIF activity acting via CD74 contributed to the recruitment of DCs to the draining lymph nodes. Mechanistically, MIF activated the Src/PI3K signaling pathway and myosin II complexes, which were required for the migration of BMDCs. Altogether, these data show that the cytokine MIF exerts chemokine-like activity for DC motility and trafficking.

Chronic kidney disease (CKD) is characterized by gradual and progressive deterioration of renal function over time, and its pathogenesis is strongly associated with immune cell imbalance, Th cell diversification, and oxidative stress. This study aimed to investigate the impact of alterations in the Th17/Treg ratio mediated by the secretory protein macrophage migration inhibitory factor (MIF) on renal injury in CKD patients. Single-cell sequencing was performed on peripheral blood mononuclear cell (PBMC) from 15 CKD patients and 20 healthy individuals to compare the characteristics of T-cell subsets, followed by differential signaling pathway analysis. Peripheral blood samples from 20 CKD patients and 10 healthy donors were analyzed using flow cytometry to quantify CD4 + T cell subsets and MIF expression. A 5/6 nephrectomy mouse model and blood CD4 + T cells were extracted to verify the effects of MIF-related proteins on the Th17/Treg ratio and progression of CKD. Besides, AAV-MIF was locally administered into the renal tissue to achieve kidney-specific MIF suppression in CKD model. Single-cell sequencing revealed significant correlation between MIF levels and Th17/Treg ratios, identifying MIF-(CD74 + CXCR4) pathway involvement. Flow cytometry analysis of the clinical cohort demonstrated an elevated Th17/Treg ratio (p < 0.01) in CKD patients compared to normal controls. MIF levels also correlated with renal parameters (Crea, p < 0.001; BUN, p < 0.0001; eGFR, p < 0.0001). In vitro experiments confirmed a significant increase (p < 0.05) in Th17/Treg cells after MIF protein or serum from CKD patients, and these changes were partially reversed by an MIF inhibitor (ISO-1) (p < 0.001). Moreover, renal injury in CKD mice in the AAV-MIF group was significantly reversed. This study revealed that MIF promotes the progression of CKD by regulating the Th17/Treg ratio and that MIF serves as a potential target to prevent CKD.Graphical MIF regulates the Th17/Treg ratio to exacerbate kidney injury in chronic kidney diseaseSupplementary InformationThe online version contains supplementary material available at 10.1007/s10753-025-02418-x.

Identification of the MIF-CD74/CD44 signaling axis as a therapeutic target in pediatric Acute Myeloid Leukemia

While it is well established that the haemodynamic cause of hypoxic pulmonary hypertension is increased pulmonary vascular resistance, the molecular pathogenesis of the increased resistance remains incompletely understood. Macrophage migration inhibitory factor is a pleiotropic cytokine with endogenous tautomerase enzymatic activity as well as both intracellular and extracellular signalling functions. In several diseases, macrophage migration inhibitory factor has pro-inflammatory roles that are dependent upon signalling through the cell surface receptors CD74, CXCR2 and CXCR4. Macrophage migration inhibitory factor expression is increased in animal models of hypoxic pulmonary hypertension and macrophage migration inhibitory factor tautomerase inhibitors, which block some of the functions of macrophage migration inhibitory factor, and have been shown to attenuate hypoxic pulmonary hypertension in mice and monocrotaline-induced pulmonary hypertension in rats. However, because of the multiple pathways through which it acts, the integrated actions of macrophage migration inhibitory factor during the development of hypoxic pulmonary hypertension were unclear. We report here that isolated lungs from adult macrophage migration inhibitory factor knockout (MIF–/–) mice maintained in normoxic conditions showed greater acute hypoxic vasoconstriction than the lungs of wild type mice (MIF+/+). Following exposure to hypoxia for three weeks, isolated lungs from MIF–/– mice had significantly higher pulmonary vascular resistance than those from MIF+/+ mice. The major mechanism underlying the greater increase in pulmonary vascular resistance in the hypoxic MIF–/– mice was reduction of the pulmonary vascular bed due to an impairment of the normal hypoxia-induced expansion of the alveolar capillary network. Taken together, these results demonstrate that macrophage migration inhibitory factor plays a central role in the development of the pulmonary vascular responses to chronic alveolar hypoxia.

Owing to its implication in a range of pathological conditions, including asthma, rheumatoid arthritis, atherosclerosis, inflammatory bowel disease and cancer, the pleiotropic cytokine macrophage migration inhibitory factor (MIF) has been the subject of intensive recent investigation. In the field of dermatology, MIF is believed to be a detrimental factor in diseases such as systemic sclerosis, atopic dermatitis, psoriasis, eczema and UV radiation damage. However, its contribution to other aspects of cutaneous biology is currently unclear. Although its expression in intact skin is well characterized, little is known about MIF's role in cutaneous homoeostasis. However, recent data do identify MIF as a key player in the immune privilege of hair follicles. Similarly, although MIF is rapidly released and its local expression significantly induced upon wounding, its primary role in the ensuing repair process remains a source of contention. MIF has been identified as being a key effector of the beneficial effects of estrogen on wound repair, yet studies employing Mif null mice, recombinant MIF, and neutralizing anti-MIF antibodies have failed to provide a consensus as to whether it benefits or inhibits healing. In fact MIF appears to be able to exert both positive and negative effects, with the cell-specific relevancy of MIF in wound healing still unclear. Thus, if MIF and/or its downstream targets are to be therapeutically useful in the context of cutaneous repair, more needs to be done to establish the nature and mechanism of action of MIF and its receptors in healing wounds.

The macrophage migration inhibitory factor (MIF) in the plasma, hydrops articuli, and synovium, and its relationship with laboratory indexes in patients with rheumatoid arthritis (RA) were determined, for the purpose to reveal the role of MIF on the pathogenesis of RA. MIF mRNA expression in PBMCs was detected by qPCR. Plasma MIF was measured by enzyme linked immunosorbent assay (ELISA). MIF in hydrops articuli and synovium from RA patientsand OA patients was evaluated by immunofluorescence (IF) and immunohistochemistry (IHC). The relationship between MIF and laboratory indexes of RA patients was analyzed. Human fibroblast-like synoviocytes (FLS) were treated with recombinant human MIF, and expression of inflammatory factors was determined by qPCR. The matrix metalloproteinase (MMP) 9 and extracellular regulated protein kinases (ERK)1/2 in FLS with MIF treatment were detected. MIF is significantly increased in plasma and hydrops articuli in RA patients. The expression of multiple inflammatory factors and MMPs was increased in RA patients and in FLS with rhMIF treatment. MIF was correlated with laboratory indexes in RA patients. Mechanistically, MIF promoted production of MMP9 by FLS through the ERK1/2 pathway. Our results indicated that increased MIF was correlated with disease activity of RA patients. These findings also suggested that MIF induced multiple inflammatory factors and MMP 9 in FLS via ERK 1/2 pathway. Key Points • MIF plays a key role in the initiation of RA by promoting the expression of various inflammatory factors in FLS and MMPs. • This study provides a basis for MIF-targeted RA clinical therapy and for exploring the feasibility of MIF as a therapeutic target for RA. • Increased MIF correlates with disease activity in RA patients.

Pseudomonas aeruginosa causes severe sight-threatening corneal infections, with the inflammatory response to the pathogen being the major factor resulting in damage to the cornea that leads to loss of visual acuity. We found that mice deficient for macrophage migration inhibitory factor (MIF), a key regulator of inflammation, had significantly reduced consequences from acute P. aeruginosa keratitis. This improvement in the outcome was manifested as improved bacterial clearance, decreased neutrophil infiltration, and decreased inflammatory responses when P. aeruginosa-infected MIF knock out (KO) mice were compared to infected wild-type mice. Recombinant MIF applied to infected corneas restored the susceptibility of MIF deficient mice to P. aeruginosa-induced disease, demonstrating that MIF is necessary and sufficient to cause significant pathology at this immune privileged site. A MIF inhibitor administered during P. aeruginosa-induced infection ameliorated the disease-associated pathology. MIF regulated epithelial cell responses to infection by enhancing synthesis of proinflammatory mediators in response to P. aeruginosa infection and by promoting bacterial invasion of corneal epithelial cells, a correlate of virulence in the keratitis model. Our results uncover a host factor that elevates inflammation and propagates bacterial cellular invasion, and further suggest that inhibition of MIF during infection may have a beneficial therapeutic effect.

Macrophage migration inhibitory factor (MIF) is a multifunctional mammalian cytokine, which exhibits tautomerase and oxidoreductase activity. MIF homologues with pairwise sequence identities to human MIF ranging from 31% to 41% have been detected in various cyanobacteria. The gene encoding the MIF homologue from the marine cyanobacterium Prochlorococcus marinus strain MIT9313 has been cloned and the corresponding protein (PmMIF) overproduced, purified, and subjected to functional and structural characterization. Kinetic and (1)H NMR spectroscopic studies show that PmMIF tautomerizes phenylenolpyruvate and (p-hydroxyphenyl)enolpyruvate at low levels. The N-terminal proline of PmMIF is critical for these reactions because the P1A mutant has strongly reduced tautomerase activities. PmMIF shows high structural homology with mammalian MIFs as revealed by a crystal structure of PmMIF at 1.63 A resolution. MIF contains a Cys-X-X-Cys motif that mediates oxidoreductase activity, which is lacking from PmMIF. Engineering of the motif into PmMIF did not result in oxidoreductase activity but increased the tautomerase activity 8-fold. The shared tautomerase activities and the conservation of the beta-alpha-beta structural fold and key functional groups suggest that eukaryotic MIFs and cyanobacterial PmMIF are related by divergent evolution from a common ancestor. While several MIF homologues have been identified in eukaryotic parasites, where they are thought to play a role in modulating the host immune response, PmMIF is the first nonparasitic, bacterial MIF-like protein characterized in detail. This work sets the stage for future studies which could address the question whether a MIF-like protein from a free-living bacterium possesses immunostimulatory features similar to those of mammalian MIFs and MIF-like proteins found in parasitic nematodes and protozoa.

Clear cell renal carcinoma (CCRC) is the most common form of renal cancer, resulting in 50,000 new cases per year in the US, and greater than 10,000 deaths. CCRC is frequently characterized by alterations in the von Hippel-Lindau protein (VHL), an E3 ligase that mediates oxygen dependent degradation of the alpha subunit of the hypoxia inducible factor (HIF). Activation of HIF and many of its transcriptional target genes are critical for renal tumorigenesis. The macrophage migration inhibitor factor (MIF) is a pleiotropic cytokine that has roles in inflammation, cell signaling, and cell cycle regulation. MIF is regulated by HIF, and is expressed in a variety of tumor types wherein MIF expression correlates with poor outcome. Functionally, MIF can negatively regulate p53, and thus may be particularly relevant in cancers like clear cell carcinoma in which p53 is not commonly mutated. The purpose if this study is to determine the role of MIF in CCRC. In order to determine if MIF is expressed in CCRC patient samples, we stained tumor microarrays with over 95 primary CCRC tumors for MIF expression. In keeping with its reported regulation by the VHL/HIF pathway, MIF demonstrated high expression in greater than 90% of the tumors compared to normal kidney samples. Likewise, in CCRC tumor cell lines MIF expression was highly expressed compared to cell lines in which VHL expression has been reconstituted. To determine the significance of MIF expression in CCRC tumor cell lines, MIF was depleted using two independent shRNAs and we observed significant decreases cell proliferation and clonogenic survival in a variety of CCRC cell lines. These observations were replicated by silencing the expression of the MIF receptor CD74, suggesting the MIF signaling pathway is intact and functional CCRC. At the mechanistic level, MIF is known to inhibit the function of p53 through promotion of MDM2 mediated degradation. To assess whether the role of MIF in CCRC is to regulate p53, we determined the effects on p53 signaling when MIF expression was inhibited. We found that inhibition of MIF lead to an increase in p53 stability and subsequent expression of the canonical p53 target gene p21. Together these observations suggest that MIF expression may play a critical role as a target of the HIF/VHL pathway that leads to the development of clear cell carcinoma. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1117. doi:10.1158/1538-7445.AM2011-1117

Macrophages play an important role in mediating damage after Spinal cord injury (SCI) by secreting macrophage migration inhibitory factor (MMIF) as a secondary injury mediator. We aimed to systematically review the role of MMIF as a therapeutic target after traumatic SCI. Our systematic review has been performed according to the PRISMA 2009 Checklist. A systematic search in the scientific databases was carried out for studies published before 20 February 2019 from major databases. Two researchers independently screened titles. The risk of bias of eligible articles was assessed, and data were extracted. Finally, we systematically analyzed and interpreted related data. 785 papers were selected for the title and abstract screening. 12 papers were included for data extraction. Eight animal studies were of high quality and the remaining two were of medium quality. One of the two human studies was of poor quality and the other was of fair quality. MMIF as a pro-inflammatory mediator can cause increased susceptibility to glutamate-related neurotoxicity, increased nitrite production, increased ERK activation, and increased COX2/PGE2 signaling pathway activation and subsequent stimulation of CCL5-related chemotaxis. Two human studies and six animal studies demonstrated that MMIF level increases after SCI. MMIF inhibition might be a potential therapeutic target in SCI by multiple different mechanisms (6/12 studies). Most animal studies demonstrate significant neurologic improvement after administration of MMIF inhibitors, but these inhibitors have not been studied in humans yet. Further clinical trials are need to further understand MMIF inhibitor utility in acute or chronic SCI. Diagnostic: individual cross-sectional studies with the consistently applied reference standard and blinding.