Advances and Insights for Small Molecule Inhibition of Macrophage Migration Inhibitory Factor

Therapeutic Opportunities in Breast Cancer by Targeting Macrophage Migration Inhibitory Factor as a Pleiotropic Cytokine

As a heterogeneous disease, breast cancer (BC) has been characterized by the uncontrolled proliferation of mammary epithelial cells. The tumor microenvironment (TME) also contains inflammatory cells, fibroblasts, the extracellular matrix (ECM), and soluble factors that all promote BC progression. In this sense, the macrophage migration inhibitory factor (MIF), a pleiotropic pro-inflammatory cytokine and an upstream regulator of the immune response, enhances breast tumorigenesis through escalating cancer cell proliferation, survival, angiogenesis, invasion, metastasis, and stemness, which then brings tumorigenic effects by activating key oncogenic signaling pathways and inducing immunosuppression. Against this background, this review was to summarize the current understanding of the MIF pathogenic mechanisms in cancer, particularly BC, and address the central role of this immunoregulatory cytokine in signaling pathways and breast tumorigenesis. Furthermore, different inhibitors, such as small molecules as well as antibodies (Abs) or small interfering RNA (siRNA) and their anti-tumor effects in BC studies were examined. Small molecules and other therapy target MIF. Considering MIF as a promising therapeutic target, further clinical evaluation of MIF-targeted agents in patients with BC was warranted.

Mechanistic insight into the mode of inhibition of dietary flavonoids; targeting macrophage migration inhibitory factor

Introduction: The Macrophage Migration Inhibitory Factor (MIF), a key pro-inflammatory mediator, is responsible for modulating immune responses. An array of inflammatory and autoimmune diseases has been linked to the dysregulated activity of MIF. The significance in physiological as well as pathophysiological phenomena underscores the potential of MIF as an attractive target with pharmacological relevance. Extensive research in past has uncovered a number of inhibitors, while the ISO-1, or (S, R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester being recognized as a benchmark standard so far. Recent work by Yang and coworkers identified five promising dietary flavonoids, with superior activity compared to the standard ISO-1. Nevertheless, the exact atomic-level inhibitory mechanism is still elusive. Methods: To improve the dynamic research, and rigorously characterize, and compare molecular signatures of MIF complexes with ISO-1 and flavonoids, principal component analysis (PCA) was linked with molecular dynamics (MD) simulations and binding free energy calculations. Results: The results suggest that by blocking the tautomerase site these small molecule inhibitors could modify the MIF activity by disrupting the intrinsic dynamics in particular functional areas. The stability matrices revealed the average deviation values ranging from 0.27-0.32 nm while the residue level fluctuations indicated that binding of the selected flavonoids confer enhanced stability relative to the ISO-1. Furthermore, the gyration values extracted from the simulated trajectories were found in the range of 1.80-1.83 nm. Discussion: Although all the tested flavonoids demonstrated remarkable results, the one obtained for the potent inhibitors, particularly Morin and Amentoflavone exhibited a good correlation with biological activity. The PCA results featured relatively less variance and constricted conformational landscape than others. The stable ensembles and reduced variation in turns might be the possible reasons for their outstanding performance documented previously. The results from the present exploration provide a comprehensive understanding of the molecular complexes formed by flavonoids and MIF, shedding light on their potential roles and impacts. Future studies on MIF inhibitors may benefit from the knowledge gathered from this investigation.

The role of MIF in periodontitis: A potential pathogenic driver, biomarker, and therapeutic target

OBJECTIVE

Periodontitis is an inflammatory disease that involves an imbalance in the oral microbiota, activation of inflammatory and immune responses, and alveolar bone destruction. Macrophage migration inhibitory factor (MIF) is a versatile cytokine involved in several pathological reactions, including inflammatory processes and bone destruction, both of which are characteristics of periodontitis. While the roles of MIF in cancer and other immune diseases have been extensively characterized, its role in periodontitis remains inconclusive.

RESULTS

In this review, we describe a comprehensive analysis of the potential roles of MIF in periodontitis from the perspective of immune response and bone regulation at the cellular and molecular levels. Moreover, we discuss its potential reliability as a novel diagnostic and therapeutic target for periodontitis.

CONCLUSION

This review can aid dental researchers and clinicians in understanding the current state of MIF-related pathogenesis, diagnosis, and treatment of periodontitis.

Unpacking Immune Modulation as a Site of Therapeutics Innovation for Nematode Parasite Wuchereria bancrofti: A Temporal Quantitative Phosphoproteomics Profiling of Macrophage Migration Inhibitory Factor 2

Nematode infections are common in both humans and livestock, with major adverse planetary health and economic impacts. Wuchereria bancrofti is a parasitic nematode that causes lymphatic filariasis, a neglected tropical disease that can lead to severe disability and deformity worldwide. For the long-term survival of the bancroftian parasites in the host, a complex immune invasion strategy is involved through immunomodulation. Therefore, immunomodulation can serve as a site of research and innovation for molecular targets. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine crucial to the host antimicrobial alarm system and stress response. Interestingly, the nematode parasite W. bancrofti also produces two homologs of MIF (Wba-MIF1 and 2). Using a mass spectrometry-based phosphoproteomics approach, we report new findings on the immunomodulatory effect and signaling mechanism of Wba-MIF2 in macrophage cells. Accordingly, we observed 1201 phosphorylated sites on 467 proteins. Out of the 1201 phosphorylated sites, 1075, 117, and 9 were found on serine (S), threonine (T), and tyrosine (Y) residues, respectively. Our bioinformatics analysis led to identification of major pathways, including spliceosomes, T cell receptor signaling pathway, Th17 differentiation pathway, interleukin-17 signaling pathway, and insulin signaling pathway upon Wba-MIF2 treatment. Wba-MIF2 treatment also enriched CDK4, CDK1, and DNAPK kinases. The comparison of the signaling pathway of Wba-MIF2 with that of human-MIF suggests both share similar signaling pathways. These findings collectively offer new insights into the role and mechanism of Wba-MIF2 as an immunomodulator and inform future diagnostics and drug discovery research for W. bancrofti.

Anti-macrophage migration inhibitory factor (MIF) activity of ibudilast: A repurposing drug attenuates the pathophysiology of leptospirosis

To develop the macrophage migration inhibitory factor (MIF) directed therapeutic approach for the treatment of leptospirosis, we identified potential MIF inhibitors by screening 10 essential tautomerase inhibition classes of chemical compounds and 7 existing anti-inflammatory and anti-microbial drugs. Dopachrome tautomerase assay was performed to measure the anti-MIF activity of selected compounds. Among 17 chemical compounds, ibudilast, an anti-inflammatory agent showed the MIF tautomerase IC50 value at a very lower concentration (9.5 ± 5.6 μM) which is considered similar to the IC50 of standard MIF antagonist, ISO-1 (6.2 ± 3.8 μM) with non-significant cytotoxicity. The in vitro analysis of the therapeutic potential of MIF inhibitor revealed that ibudilast significantly reduced the leptospiral lipopolysaccharide (LPS) mediated expression of inflammatory mediators such as intercellular adhesion molecule (ICAM), p38 and p44/42 mitogen-activated protein kinase (MAPK), inflammatory cytokines, and decreased the reactive oxygen species (ROS) production, mitochondrial membrane potential (ΔΨm) loss and cell death of LPS treated THP-1 cells. In vivo analysis demonstrated that the administration of anti-MIF Ibudilast significantly reduced the histopathological changes, downregulates the pro-inflammatory cytokines, and protects the leptospiral BALB/c model from lethality by increasing the survival rate from 25% to 66%. Finally, the biocompatibility of the evaluated anti-MIF compound was explored by cytotoxicity, hemocompatibility, and cell death assay. Ibudilast showed no significant cytotoxicity and hemolytic activity was noticed even at the higher concentration of ≤50 μM and ≥250 μM, when compared with the positive control, 0.1% Triton X-100; no significant cell death was observed at ≤50 μM concentration of Ibudilast in THP-1 cells. From these lines of evidence, we propose that Ibudilast may be a great MIF targeting repurposing drug for reliable supportive treatment of severe leptospirosis.

Immunomodulatory Role of Thioredoxin Interacting Protein in Cancer's Impediments: Current Understanding and Therapeutic Implications

Cancer, which killed ten million people in 2020, is expected to become the world's leading health problem and financial burden. Despite the development of effective therapeutic approaches, cancer-related deaths have increased by 25.4% in the last ten years. Current therapies promote apoptosis and oxidative stress DNA damage and inhibit inflammatory mediators and angiogenesis from providing temporary relief. Thioredoxin-binding protein (TXNIP) causes oxidative stress by inhibiting the function of the thioredoxin system. It is an important regulator of many redox-related signal transduction pathways in cells. In cancer cells, it functions as a tumor suppressor protein that inhibits cell proliferation. In addition, TXNIP levels in hemocytes increased after immune stimulation, suggesting that TXNIP plays an important role in immunity. Several studies have provided experimental evidence for the immune modulatory role of TXNIP in cancer impediments. TXNIP also has the potential to act against immune cells in cancer by mediating the JAK-STAT, MAPK, and PI3K/Akt pathways. To date, therapies targeting TXNIP in cancer are still under investigation. This review highlights the role of TXNIP in preventing cancer, as well as recent reports describing its functions in various immune cells, signaling pathways, and promoting action against cancer.

OxMIF: a druggable isoform of macrophage migration inhibitory factor in cancer and inflammatory diseases

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with a pleiotropic spectrum of biological functions implicated in the pathogenesis of cancer and inflammatory diseases. MIF is constitutively present in several cell types and non-lymphoid tissues and is secreted after acute stress or inflammation. MIF triggers the release of proinflammatory cytokines, overrides the anti-inflammatory effects of glucocorticoids, and exerts chemokine function, resulting in increased migration and recruitment of leukocytes into inflamed tissue. Despite this, MIF is a challenging target for therapeutic intervention because of its ubiquitous nature and presence in the circulation and tissue of healthy individuals. Oxidized MIF (oxMIF) is an immunologically distinct disease-related structural isoform found in the plasma and tissues of patients with inflammatory diseases and in solid tumor tissues. MIF converts to oxMIF in an oxidizing, inflammatory environment. This review discusses the biology and activity of MIF and the potential for autoimmune disease and cancer modification by targeting oxMIF. Anti-oxMIF antibodies reduce cancer cell invasion/migration, angiogenesis, proinflammatory cytokine production, and ERK and AKT activation. Anti-oxMIF antibodies also elicit apoptosis and alter immune cell function and/or migration. When co-administered with a glucocorticoid, anti-oxMIF antibodies produced a synergistic response in inflammatory models. Anti-oxMIF antibodies therefore counterregulate biological activities attributed to MIF. oxMIF expression has been observed in inflammatory diseases (eg, sepsis, psoriasis, asthma, inflammatory bowel disease, and systemic lupus erythematosus) and oxMIF has been detected in ovarian, colorectal, lung, and pancreatic cancers. In contrast to MIF, oxMIF is specifically detected in plasma and/or tissues of diseased patients, but not in healthy individuals. Therefore, as a druggable isoform of MIF, oxMIF represents a potential new therapeutic target in inflammatory diseases and cancer. Fully human, monoclonal anti-oxMIF antibodies have been shown to selectively bind oxMIF in preclinical and phase I studies; however, additional clinical assessments are necessary to validate their use as either a monotherapy or in combination with standard-of-care regimens (ie, immunomodulatory agents/checkpoint inhibitors, anti-angiogenic drugs, chemotherapeutics, and glucocorticoids).

Macrophage Migration Inhibitory Factor (MIF) Makes Complex Contributions to Pain-Related Hyperactivity of Nociceptors after Spinal Cord Injury

Neuropathic pain is a major, inadequately treated challenge for people with spinal cord injury (SCI). While SCI pain mechanisms are often assumed to be in the CNS, rodent studies have revealed mechanistic contributions from primary nociceptors. These neurons become chronically hyperexcitable after SCI, generating ongoing electrical activity that promotes ongoing pain. A major question is whether extrinsic chemical signals help to drive ongoing electrical activity after SCI. People living with SCI exhibit acute and chronic elevation of circulating levels of macrophage migration inhibitory factor (MIF), a cytokine implicated in preclinical pain models. Probable nociceptors isolated from male rats and exposed to an MIF concentration reported in human plasma (1 ng/ml) showed hyperactivity similar to that induced by SCI, although, surprisingly, a 10-fold higher concentration failed to increase excitability. Conditioned behavioral aversion to a chamber associated with peripheral MIF injection suggested that MIF stimulates affective pain. A MIF inhibitor, Iso-1, reversed SCI-induced hyperexcitability. Unlike chronic SCI-induced hyperexcitability, acute MIF-induced hyperexcitability was only partially abrogated by inhibiting ERK signaling. Unexpectedly, MIF concentrations that induced hyperactivity in nociceptors from naive animals, after SCI induced a long-lasting conversion from a highly excitable nonaccommodating type to a rapidly accommodating, hypoexcitable type, possibly as a homeostatic response to prolonged depolarization. Treatment with conditioned medium from cultures of DRG cells obtained after SCI was sufficient to induce MIF-dependent hyperactivity in neurons from naive rats. Thus, changes in systemic and DRG levels of MIF may help to maintain SCI-induced nociceptor hyperactivity that persistently promotes pain.SIGNIFICANCE STATEMENT Chronic neuropathic pain is a major challenge for people with spinal cord injury (SCI). Pain can drastically impair quality of life, and produces substantial economic and social burdens. Available treatments, including opioids, remain inadequate. This study shows that the cytokine macrophage migration inhibitory factor (MIF) can induce pain-like behavior and plays an important role in driving persistent ongoing electrical activity in injury-detecting sensory neurons (nociceptors) in a rat SCI model. The results indicate that SCI produces an increase in MIF release within sensory ganglia. Low MIF levels potently excite nociceptors, but higher levels trigger a long-lasting hypoexcitable state. These findings suggest that therapeutic targeting of MIF in neuropathic pain states may reduce pain and sensory dysfunction by curbing nociceptor hyperactivity.

Discovery of novel MIF inhibitors that attenuate microglial inflammatory activation by structures-based virtual screening and in vitro bioassays

Macrophage migration inhibitory factor (MIF) is a pluripotent pro-inflammatory cytokine and is related to acute and chronic inflammatory responses, immune disorders, tumors, and other diseases. In this study, an integrated virtual screening strategy and bioassays were used to search for potent MIF inhibitors. Twelve compounds with better bioactivity than the prototypical MIF-inhibitor ISO-1 (IC₅₀ = 14.41 μM) were identified by an in vitro enzymatic activity assay. Structural analysis revealed that these inhibitors have novel structural scaffolds. Compound 11 was then chosen for further characterization in vitro, and it exhibited marked anti-inflammatory efficacy in LPS-activated BV-2 microglial cells by suppressing the activation of nuclear factor kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs). Our findings suggest that MIF may be involved in the regulation of microglial inflammatory activation and that small-molecule MIF inhibitors may serve as promising therapeutic agents for neuroinflammatory diseases.

Macrophage Migration Inhibitory Factor (MIF) as a Stress Molecule in Renal Inflammation

Renal inflammation is an initial pathological process during progressive renal injury regardless of the initial cause. Macrophage migration inhibitory factor (MIF) is a truly proinflammatory stress mediator that is highly expressed in a variety of both inflammatory cells and intrinsic kidney cells. MIF is released from the diseased kidney immediately upon stimulation to trigger renal inflammation by activating macrophages and T cells, and promoting the production of proinflammatory cytokines, chemokines, and stress molecules via signaling pathways involving the CD74/CD44 and chemokine receptors CXCR2, CXCR4, and CXCR7 signaling. In addition, MIF can function as a stress molecule to counter-regulate the immunosuppressive effect of glucocorticoid in renal inflammation. Given the critical position of MIF in the upstream inflammatory cascade, this review focuses on the regulatory role and molecular mechanisms of MIF in kidney diseases. The therapeutic potential of targeting MIF signaling to treat kidney diseases is also discussed.

Novel regulators of airway epithelial barrier function during inflammation: potential targets for drug repurposing

INTRODUCTION

Endogenous inflammatory signaling molecules resulting from deregulated immune responses, can impair airway epithelial barrier function and predispose individuals with airway inflammatory diseases to exacerbations and lung infections. Targeting the specific endogenous factors disrupting the airway barrier therefore has the potential to prevent disease exacerbations without affecting the protective immune responses.

AREAS COVERED

Here, we review the endogenous factors and specific mechanisms disrupting airway epithelial barrier during inflammation and reflect on whether these factors can be specifically targeted by repurposed existing drugs. Literature search was conducted using PubMed, drug database of US FDA and European Medicines Agency until and including September 2021.

EXPERT OPINION

IL-4 and IL-13 signaling are the major pathways disrupting the airway epithelial barrier during airway inflammation. However, blocking IL-4/IL-13 signaling may adversely affect protective immune responses and increase susceptibility of host to infections. An alternate approach to modulate airway epithelial barrier function involves targeting specific downstream component of IL-4/IL-13 signaling or different inflammatory mediators responsible for regulation of airway epithelial barrier. Airway epithelium-targeted therapy using inhibitors of HDAC, HSP90, MIF, mTOR, IL-17A and VEGF may be a potential strategy to prevent airway epithelial barrier dysfunction in airway inflammatory diseases.

Thieno[2,3-d]pyrimidine-2,4(1H,3H)-dione Derivative Inhibits d-Dopachrome Tautomerase Activity and Suppresses the Proliferation of Non-Small Cell Lung Cancer Cells

The homologous cytokines macrophage migration inhibitory factor (MIF) and d-dopachrome tautomerase (d-DT or MIF2) play key roles in cancers. Molecules binding to the MIF tautomerase active site interfere with its biological activity. In contrast, the lack of potent MIF2 inhibitors hinders the exploration of MIF2 as a drug target. In this work, screening of a focused compound collection enabled the identification of a MIF2 tautomerase inhibitor R110. Subsequent optimization provided inhibitor 5d with an IC₅₀ of 1.0 μM for MIF2 tautomerase activity and a high selectivity over MIF. 5d suppressed the proliferation of non-small cell lung cancer cells in two-dimensional (2D) and three-dimensional (3D) cell cultures, which can be explained by the induction of cell cycle arrest via deactivation of the mitogen-activated protein kinase (MAPK) pathway. Thus, we discovered and characterized MIF2 inhibitors (5d) with improved antiproliferative activity in cellular models systems, which indicates the potential of targeting MIF2 in cancer treatment.

Molecular Level Insights Into the Structural and Dynamic Factors Driving Cytokine Function

Cytokines are key mediators of cellular communication and regulators of biological advents. The timing, quantity and localization of cytokines are key features in producing specific biological outcomes, and thus have been thoroughly studied and reviewed while continuing to be a focus of the cytokine biology community. Due to the complexity of cellular signaling and multitude of factors that can affect signaling outcomes, systemic level studies of cytokines are ongoing. Despite their small size, cytokines can exhibit structurally promiscuous and dynamic behavior that plays an equally important role in biological activity. In this review using case studies, we highlight the recent insight gained from observing cytokines through a molecular lens and how this may complement a system-level understanding of cytokine biology, explain diversity of downstream signaling events, and inform therapeutic and experimental development.

Repurposing Old Drugs as Novel Inhibitors of Human MIF from Structural and Functional Analysis

Human macrophage migration inhibitory factor (MIF) is an important pro-inflammatory cytokine that plays multiple pleiotropic functions. It is considered as a promising therapeutic target for the infectious, autoimmune, and cardiovascular diseases and cancers. The development of MIF inhibitors has not been translated into clinical success despite decades of research. Given the time and cost of developing new drugs, existing drugs with clarified safety and pharmacokinetics are explored for their potential as novel MIF inhibitors. This study identified five known drugs that could inhibit MIF's tautomerase activity and MIF-mediated cell chemotaxis in RAW264.7 cells. It was found that compounds D2 (histamine), D5 (metaraminol), and D8 (nebivolol) exhibited micromolar-range inhibition potency close to the positive control ISO-1. Kinetics and the mechanism for inhibition were subsequently determined. Moreover, the detailed inhibitor-binding patterns were investigated by X-ray crystallography, computational molecular docking, and structure-based analysis. Therefore, this study elucidates the molecular mechanism of repurposed drugs acting on MIF and provides a structural foundation for lead optimization to promote the clinical development of MIF-targeted drugs.

4-Iodopyrimidine Labeling Reveals Nuclear Translocation and Nuclease Activity for Both MIF and MIF2*

Macrophage migration inhibitory factor (MIF) and its homolog MIF2 (also known as D‐dopachrome tautomerase or DDT) play key roles in cell growth and immune responses. MIF and MIF2 expression is dysregulated in cancers and neurodegenerative diseases. Accurate and convenient detection of MIF and MIF2 will facilitate research on their roles in cancer and other diseases. Herein, we report the development and application of a 4‐iodopyrimidine based probe 8 for the selective labeling of MIF and MIF2. Probe 8 incorporates a fluorophore that allows in situ imaging of these two proteins. This enabled visualization of the translocation of MIF2 from the cytoplasm to the nucleus upon methylnitronitrosoguanidine stimulation of HeLa cells. This observation, combined with literature on nuclease activity for MIF, enabled the identification of nuclease activity for MIF2 on human genomic DNA.

Macrophage migration inhibitory factor (MIF) inhibitor 4-IPP downregulates stemness phenotype and mesenchymal trans-differentiation after irradiation in glioblastoma multiforme

Radiation therapy is among the most essential treatment methods for glioblastoma multiforme (GBM). Radio-resistance and cancer stem cell properties can cause therapeutic resistance, cancer heterogeneity, and poor prognoses in association with GBM. Furthermore, the GBM subtype transition from proneural to the most malignant mesenchymal subtype after radiation therapy also accounts for high resistance to conventional treatments. Here, we demonstrate that the inhibition of macrophage migration inhibitory factor (MIF) and D-dopachrome tautomerase (DDT) by 4-iodo-6-phenylpyrimidine (4-IPP), a dual inhibitor targeting MIF and DDT, downregulates stemness phenotype, intracellular signaling cascades, mesenchymal trans-differentiation, and induces apoptosis in proneural glioma stem cells (GSCs). In an analysis of The Cancer Genome Atlas, high MIF and DDT expression were associated with poor prognosis. GSC growth was effectively inhibited by 4-IPP in a time- and dose-dependent manner, and 4-IPP combined with radiation therapy led to significantly reduced proliferation compared with radiation therapy alone. The expression of stemness factors, such as Olig2 and SOX2, and the expression of pAKT, indicating PI3K signaling pathway activation, were decreased in association with both 4-IPP monotherapy and combination treatment. The expression of mesenchymal markers, TGM2 and NF-κB, and expression of pERK (indicating MAPK signaling pathway activation) increased in association with radiation therapy alone but not with 4-IPP monotherapy and combination therapy. In addition, the combination of 4-IPP and radiation therapy significantly induced apoptosis compared to the monotherapy of 4-IPP or radiation. In vivo results demonstrated a significant tumor-suppressing effect of 4-IPP when combined with radiation therapy. Collectively, our results showed that the targeted inhibition of MIF and DDT has the potential to strengthen current clinical strategies by enhancing the anticancer effects of radiation therapy.

Identification and Structure-Activity Relationships of Dietary Flavonoids as Human Macrophage Migration Inhibitory Factor (MIF) Inhibitors

Dietary flavonoids are known to have anti-inflammatory and anticancer effects, but their influences on human macrophage migration inhibitory factor (MIF), a vital proinflammatory cytokine recognized as a therapeutic target for infectious diseases and cancers, have been rarely reported. Here, we identified 24 dietary flavonoids that could inhibit the tautomerase activity of MIF, five of which exerted IC₅₀ values lower than the positive control ISO-1 in the micromolar range: morin (IC₅₀ = 11.01 ± 0.45 μM) and amentoflavone (IC₅₀ = 13.32 ± 0.64 μM) exhibited the most potent efficacy followed by apigenin (IC₅₀ = 42.74 ± 4.20 μM), naringin (IC₅₀ = 51.38 ± 2.12 μM), and fisetin (IC₅₀ = 51.99 ± 0.63 μM). X-ray crystallography, molecular docking, and cellular experiments were utilized to illustrate the molecular binding details and structure-activity relationships. Scaffold modifications of flavonoids significantly influenced the potency. What stands out for morin is the unique 2'-OH substitution. In addition, amentoflavone situated at the MIF trimer pore may impact MIF-CD74 signaling. The results also showed that flavonoids could suppress cell chemotaxis and nitric oxide production in RAW264.7 cells. Our results elucidate the molecular mechanism of flavonoids acting on MIF and shed light on developing lead compounds against MIF-involved diseases.

The role of serum macrophage migration inhibitory factor in preoperative prediction of chronic rhinosinusitis with nasal polyps endotypes

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a highly heterogeneous disease and can be categorized into eosinophilic CRSwNP (eCRSwNP) and non-eosinophilic CRSwNP (neCRSwNP). Exploring effective biomarkers to distinguish endotypes is important for personalized therapies. The present study aims to evaluate the predictive value of serum MIF in CRSwNP endotypes.

METHODS

One hundred and twenty CRSwNP patients, including 51 eCRSwNP and 69 neCRSwNP, 40 chronic rhinosinusitis without nasal polyps (CRSsNP) patients and 40 healthy controls (HC) were enrolled. Serum MIF levels were determined by enzyme-linked immunosorbent assay (ELISA). The patients' clinical variables were analyzed for correlations with serum MIF. Receiver operating characteristic (ROC) curve and multivariate analysis were utilized to assess the predictive value of serum MIF in CRSwNP endotypes.

RESULTS

The serum MIF levels were significantly higher in CRSwNP group than CRSsNP group and HC group (P < 0.001), and the serum MIF levels were increased in eCRSwNP compared to neCRSwNP group (P = 0.006). Elevated serum MIF levels were significantly correlated with blood eosinophil (B-EOS) count (r = 0.411, P < 0.001), B-EOS percentage (r = 0.377, P < 0.001), visual analog scale score (r = 0.204, P = 0.025), tissue eosinophil (T-EOS) count (r = 0.705, P < 0.001) and T-EOS percentage (r = 0.671, P < 0.001) in CRSwNP patients. ROC curve demonstrated that serum MIF exhibited good preoperative prediction in CRSwNP endotypes (area under the curve = 0.925, P < 0.001). Multivariate regression analysis showed that serum MIF was an independent factor associated with CRSwNP endotypes.

CONCLUSIONS

This was the first study identifying serum MIF as a possible specific biomarker for preoperatively distinguishing CRSwNP endotypes. Furthermore, the serum MIF levels were found to be closely associated with the degree of mucosal eosinophil infiltration.

Proteolysis Targeting Chimera (PROTAC) for Macrophage Migration Inhibitory Factor (MIF) Has Anti-Proliferative Activity in Lung Cancer Cells

Macrophage migration inhibitory factor (MIF) is involved in protein-protein interactions that play key roles in inflammation and cancer. Current strategies to develop small molecule modulators of MIF functions are mainly restricted to the MIF tautomerase active site. Here, we use this site to develop proteolysis targeting chimera (PROTAC) in order to eliminate MIF from its protein-protein interaction network. We report the first potent MIF-directed PROTAC, denoted MD13, which induced almost complete MIF degradation at low micromolar concentrations with a DC50 around 100 nM in A549 cells. MD13 suppresses the proliferation of A549 cells, which can be explained by deactivation of the MAPK pathway and subsequent induction of cell cycle arrest at the G2/M phase. MD13 also exhibits antiproliferative effect in a 3D tumor spheroid model. In conclusion, we describe the first MIF-directed PROTAC (MD13) as a research tool, which also demonstrates the potential of PROTACs in cancer therapy.

Antiviral potential of plant polysaccharide nanoparticles actuating non-specific immunity

The development of high-end targeted drugs and vaccines against modern pandemic infections, such as COVID-19, can take a too long time that lets the epidemic spin up and harms society. However, the countermeasures must be applied against the infection in this period until the targeted drugs became available. In this regard, the non-specific, broad-spectrum anti-viral means could be considered as a compromise allowing overcoming the period of trial. One way to enhance the ability to resist the infection is to activate the nonspecific immunity using a suitable driving-up agent, such as plant polysaccharides, particularly our drug Panavir isolated from the potato shoots. Earlier, we have shown the noticeable anti-viral and anti-bacterial activity of Panavir. Here we demonstrate the pro-inflammation activity of Panavir, which four-to-eight times intensified the ATP and MIF secretion by HL-60 cells. This effect was mediated by the active phagocytosis of the Panavir particles by the cells. We hypothesized the physiological basis of the Panavir proinflammatory activity is mediated by the indol-containing compounds (auxins) present in Panavir and acting as a plant analog of serotonin.

Advances in immunological research of amphioxus

Amphioxus, one of the most closely related invertebrates to vertebrates, is an important animal model for studying the origin and evolution of vertebrate immunity, especially the transition from innate immunity to adaptive immunity. The current research progresses of amphioxus in the field of immune organs, immune cells, complement system, cytokines, nuclear factor kappa B, immune-related lectins and enzymes are summarized, and some issues that remain to be understood or are in need of further clarification are highlighted. We hope to provide references for more in-depth study of the amphioxus immune system and lay a solid foundation for the construction of three-dimensional immune network in amphioxus from ontogeny to phylogeny.

Targeting Macrophage Migration Inhibitory Factor in Acute Pancreatitis and Pancreatic Cancer

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine implicated in the pathogenesis of inflammation and cancer. It is produced by various cells and circulating MIF has been identified as a biomarker for a range of diseases. Extracellular MIF mainly binds to the cluster of differentiation 74 (CD74)/CD44 to activate downstream signaling pathways. These in turn activate immune responses, enhance inflammation and can promote cancer cell proliferation and invasion. Extracellular MIF also binds to the C-X-C chemokine receptors cooperating with or without CD74 to activate chemokine response. Intracellular MIF is involved in Toll-like receptor and inflammasome-mediated inflammatory response. Pharmacological inhibition of MIF has been shown to hold great promise in treating inflammatory diseases and cancer, including small molecule MIF inhibitors targeting the tautomerase active site of MIF and antibodies that neutralize MIF. In the current review, we discuss the role of MIF signaling pathways in inflammation and cancer and summarize the recent advances of the role of MIF in experimental and clinical exocrine pancreatic diseases. We expect to provide insights into clinical translation of MIF antagonism as a strategy for treating acute pancreatitis and pancreatic cancer.

MIF-Dependent Control of Tumor Immunity

Initially identified as a T lymphocyte-elicited inhibitor of macrophage motility, macrophage migration inhibitory factor (MIF) has since been found to be expressed by nearly every immune cell type examined and overexpressed in most solid and hematogenous malignant cancers. It is localized to both extracellular and intracellular compartments and physically interacts with more than a dozen different cell surface and intracellular proteins. Although classically associated with and characterized as a mediator of pro-inflammatory innate immune responses, more recent studies demonstrate that, in malignant disease settings, MIF contributes to anti-inflammatory, immune evasive, and immune tolerant phenotypes in both innate and adaptive immune cell types. This review will summarize the studies describing MIF in tumor-specific innate and adaptive immune responses and attempt to reconcile these various pleiotropic functions in normal physiology.

7-Hydroxycoumarins Are Affinity-Based Fluorescent Probes for Competitive Binding Studies of Macrophage Migration Inhibitory Factor

Macrophage migration inhibitory factor (MIF) is a cytokine with key roles in inflammation and cancer, which qualifies it as a potential drug target. Apart from its cytokine activity, MIF also harbors enzyme activity for keto–enol tautomerization. MIF enzymatic activity has been used for identification of MIF binding molecules that also interfere with its biological activity. However, MIF tautomerase activity assays are troubled by irregularities, thus creating a need for alternative methods. In this study, we identified a 7-hydroxycoumarin fluorophore with high affinity for the MIF tautomerase active site (K_i = 18 ± 1 nM) that binds with concomitant quenching of its fluorescence. This property enabled development of a novel competition-based assay format to quantify MIF binding. We also demonstrated that the 7-hydroxycoumarin fluorophore interfered with the MIF–CD74 interaction and inhibited proliferation of A549 cells. Thus, we provide a high-affinity MIF binder as a novel tool to advance MIF-oriented research.

Inhibition of Macrophage Migration Inhibitory Factor by a Chimera of Two Allosteric Binders

Human Macrophage Migration Inhibitory Factor (MIF) is a trimeric cytokine implicated in a number of inflammatory and autoimmune diseases and cancer. We previously reported that the dye p425 (Chicago Sky Blue), which bound MIF at the interface of two MIF trimers covering the tautomerase and allosteric pockets, revealed a unique strategy to block MIF's pro-inflammatory activities. Structural liabilities, including the large size, precluded p425 as a medicinal chemistry lead for drug development. We report here a rational design strategy linking only the fragment of p425 that binds over the tautomerase pocket to the core of ibudilast, a known MIF allosteric site-specific inhibitor. The chimeric compound, termed L2-4048, was shown by X-ray crystallography to bind at the allosteric and tautomerase sites as anticipated. L2-4048 retained target binding and blocked MIF's tautomerase CD74 receptor binding, and pro-inflammatory activities. Our studies lay the foundation for the design and synthesis of smaller and more drug-like compounds that retain the MIF inhibitory properties of this chimera.

Migration Inhibitory Factor in Conditioned Medium from Human Umbilical Cord Blood-Derived Mesenchymal Stromal Cells Stimulates Hair Growth

Conventional therapeutic applications of mesenchymal stromal cells (MSCs) focus on cell replacement and differentiation; however, increasing evidence suggests that most of their therapeutic effects are carried out by their various secretions. This study investigated the application of conditioned medium (CM) from human umbilical cord blood-derived MSCs (hUCB-MSCs) to improve hair growth and developed a method to reliably produce this optimized CM. Primed MSC-derived CM (P-CM) with combinations of TGF-β1 and LiCl was optimized by comparing its effects on the cell viability of dermal papilla cells (DPCs). P-CM significantly increased the viability of DPCs compared to CM. The secretion of vascular endothelial growth factor (VEGF) in DPCs was regulated by the macrophage migration inhibitory factor (MIF) in the P-CM secreted by MSCs. These findings suggest that P-CM can improve the efficacy in hair growth via a paracrine mechanism and that MIF in P-CM exerts hair growth-promoting effects via a VEGF-related β-catenin and p-GSK-3β [SER9] signaling pathway. Furthermore, clinical trials have shown that 5% P-CM improved androgenetic alopecia through producing an increased hair density, thickness, and growth rate, suggesting that this topical agent may be a novel and effective treatment option for patients with androgenetic alopecia.

Remodeling adipose tissue inflammasome for type 2 diabetes mellitus treatment: Current perspective and translational strategies

Obesity-associated type 2 diabetes mellitus (T2DM) is characterized by low-grade chronic systemic inflammation that arises primarily from the white adipose tissue. The interplay between various adipose tissue-derived chemokines drives insulin resistance in T2DM and has therefore become a subject of rigorous investigation. The adipocytokines strongly associated with glucose homeostasis include tumor necrosis factor-α, various interleukins, monocyte chemoattractant protein-1, adiponectin, and leptin, among others. Remodeling the adipose tissue inflammasome in obesity-associated T2DM is likely to treat the underlying cause of the disease and bring significant therapeutic benefit. Various strategies have been adopted or are being investigated to modulate the serum/tissue levels of pro- and anti-inflammatory adipocytokines to improve glucose homeostasis in T2DM. These include use of small molecule agonists/inhibitors, mimetics, antibodies, gene therapy, and other novel formulations. Here, we discuss adipocytokines that are strongly associated with insulin activity and therapies that are under investigation for modulation of their levels in the treatment of T2DM.

Emerging Role of the Macrophage Migration Inhibitory Factor Family of Cytokines in Neuroblastoma. Pathogenic Effectors and Novel Therapeutic Targets?

Neuroblastoma (NB) is the most frequent extracranial pediatric tumor. Despite the current available multiple therapeutic options, the prognosis for high-risk NB patients remains unsatisfactory and makes the disease a clear unmet medical need. Thus, more tailored therapeutic approaches are warranted to improve both the quality of life and the survival of the patients. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that plays a key role in several diseases, including cancer. Preclinical and clinical studies in NB patients convergently indicate that MIF exerts pro-tumorigenic properties in NB. MIF is upregulated in NB tumor tissues and cell lines and it contributes to NB aggressiveness and immune-escape. To date, there are only a few data about the role of the second member of the MIF family, the MIF homolog d-dopachrome tautomerase (DDT), in NB. Here, we review the preclinical and clinical studies on the role of the MIF family of cytokines in NB and suggest that MIF and possibly DDT inhibitors may be promising novel prognostic and therapeutic targets in NB management.

Measurement of serum macrophage migration inhibitory factor (MIF) and correlation with severity and pruritus scores in client owned dogs with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a common inflammatory skin disease of dogs. Macrophage migration inhibitory factor (MIF) initiates pro-inflammatory cytokine release in human AD and serum concentrations are correlated with disease severity.

HYPOTHESIS

Canine serum MIF concentrations are increased in dogs with AD and correlate with clinical lesion and pruritus scores.

ANIMALS

Client owned dogs (n = 49) diagnosed with AD and 17 healthy, unaffected control dogs were used for the study.

METHODS AND MATERIALS

A commercially available MIF ELISA was optimized for the dog and serum from clinical cases used. Information regarding treatment, Canine Atopic Dermatitis Extent and Severity Index, (CADESI-4) and pruritus Visual Analog Scale (pVAS) were recorded for each dog at the time of serum collection.

RESULTS

Dogs with AD which had not received steroid therapy and those treated with oclacitinib had significantly elevated serum MIF concentrations compared to controls. Concentrations of MIF were not significantly different in AD dogs receiving steroids compared to controls. There was no significant correlation between MIF concentrations and clinical scores (CADESI-4 or pVAS).

CONCLUSIONS AND CLINICAL IMPORTANCE

Serum MIF concentrations are increased in dogs with AD and MIF might be a target for therapy.

The Multitasking Potential of Alarmins and Atypical Chemokines

When the human genome was sequenced, it came as a surprise that it contains “only” 21,306 protein-coding genes. However, complexity and diversity are multiplied by alternative splicing, non-protein-coding transcripts, or post-translational modifications (PTMs) on proteome level. Here, we discuss how the multi-tasking potential of proteins can substantially enhance the complexity of the proteome further, while at the same time offering mechanisms for the fine-regulation of cell responses. Discoveries over the past two decades have led to the identification of “surprising” and previously unrecognized functionalities of long known cytokines, inflammatory mediators, and intracellular proteins that have established novel molecular networks in physiology, inflammation, and cardiovascular disease. In this mini-review, we focus on alarmins and atypical chemokines such as high-mobility group box protein-1 (HMGB-1) and macrophage migration-inhibitory factor (MIF)-type proteins that are prototypical examples of these classes, featuring a remarkable multitasking potential that allows for an elaborate fine-tuning of molecular networks in the extra- and intracellular space that may eventually give rise to novel “task”-based precision medicine intervention strategies.

Macrophage Migration Inhibitory Factor (MIF) Inhibition in a Murine Model of Bleomycin-Induced Pulmonary Fibrosis

Background: Pulmonary hypertension (PH) is a common complication of idiopathic pulmonary fibrosis (IPF) that significantly contributes to morbidity and mortality. Macrophage migration inhibitory factor (MIF) is a critical factor in vascular remodeling of the pulmonary circulation. Objectives: We tested the effects of two small molecules targeting MIF on bleomycin (BLM)-induced collagen deposition, PH, and vascular remodeling in mouse lungs. Methods: We examined the distribution pattern of MIF, CD74, and CXCR4 in the lungs of patients with IPF-PH and the lungs of BLM-injected mice. Then, treatments were realized with (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1) and N-(3-hydroxy-4-fluorobenzyl)-5 trifluoromethylbenzoxazol-2-thione 31 (20 mg/kg/day per os for 3 weeks) started 24 h after an intratracheal BLM administration. Results: More intense immunoreactivity was noted for MIF, CD74, and CXCR4 in lungs from IPF-PH patients and BLM-injected mice. Furthermore, we found that treatments of BLM-injected mice with ISO-1 or compound 31 attenuated lung collagen deposition and right ventricular systolic pressure increase. Additionally, reduced pulmonary inflammatory infiltration and pulmonary arterial muscularization were observed in the lungs of BLM-injected mice treated with ISO-1 or compound 31. Conclusions: Treatments with ISO-1 or compound 31 attenuates BLM-induced inflammation and fibrosis in lung, and prevents PH development in mice, suggesting that MIF is an important factor for IPF-PH development.

Role of MIF and D-DT in immune-inflammatory, autoimmune, and chronic respiratory diseases: from pathogenic factors to therapeutic targets

Macrophage migration inhibitory factor (MIF) is a protein that acts as a cytokine-, enzyme-, endocrine- and chaperon-like molecule. It binds to the cell-surface receptor CD74 in association with CD44, which activates the downstream signal transduction pathway. In addition, MIF acts also as a noncognate ligand for C-X-C chemokine receptor type 2 (CXCR2), type 4 (CXCR4), and type 7 (CXCR7). Recently, D-dopachrome tautomerase (D-DT), a second member of the MIF superfamily, was identified. From a pharmacological and clinical point of view, the nonredundant biological properties of MIF and D-DT anticipate potential synergisms from their simultaneous inhibition. Here, we focus on the role of MIF and D-DT in human immune-inflammatory, autoimmune, and chronic respiratory diseases, providing an update on the progress made in the identification of specific small-molecule inhibitors of these proteins.