Macrophage migration inhibitory factor (MIF) promotes fibroblast migration in scratch-wounded monolayers in vitro

Bioactive coating provides antimicrobial protection through immunomodulation and phage therapeutics

Medical implant-associated infections (IAI) is a growing threat to patients undergoing implantation surgery. IAI prevention typically relies on medical implants endowed with bactericidal properties achieved through surface modifications with antibiotics. However, the clinical efficacy of this traditional paradigm remains suboptimal, often necessitating revision surgery and posing potentially lethal consequences for patients. To bolster the existing anti-IAI arsenal, we propose herein a chitosan-based bioactive coating, i.e., ChitoAntibac, which exerts bacteria-inhibitory effects either through immune modulation or phage-directed microbial clearance, without relying on conventional antibiotics. The immuno-stimulating effects and phage-induced bactericidal properties can be tailored by engineering the loading dynamic of macrophage migration inhibitory factor (MIF), which polarizes macrophages towards the proinflammatory subtype (M1) with enhanced bacterial phagocytosis, and Staphylococcal Phage K, resulting in rapid and targeted pathogenic clearance (>99.99%) in less than 8 h. Our innovative antibacterial coating opens a new avenue in the pursuit of effective IAI prevention through immuno-stimulation and phage therapeutics.

WISP1 induces the expression of macrophage migration inhibitory factor in human lung fibroblasts through Src kinases and EGFR-activated signaling pathways

Wnt1-inducible signaling protein 1 (WISP1/CCN4) is a secreted matricellular protein that is implicated in lung and airway remodeling. The macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that has been associated with chronic lung diseases. In this study, we aimed to investigate the WISP1 signaling pathway and its ability to induce the expression of MIF in primary cultures of fibroblasts from normal human lungs (HLFs). Our results showed that WISP1 significantly stimulated the expression of MIF in a concentration- and time-dependent fashion. In WISP1-induced expression of MIF, αvβ5-integrin and chondroitin sulfate proteoglycans as well as Src tyrosine kinases, MAP kinases, phosphatidylinositol 3-kinase/Akt, PKC, and NF-κB were involved. WISP1-induced expression of MIF was attenuated in the presence of the Src kinase inhibitor PP2 or the MIF tautomerase activity inhibitor ISO-1. Moreover, WISP1 significantly increased the phosphorylation and activation of EGF receptor (EGFR) through transactivation by Src kinases. WISP1 also induced the expression of MIF receptor CD74 and coreceptor CD44, through which MIF exerts its effects on HLFs. In addition, it was found that MIF induced its own expression, as well as its receptors CD74/CD44, acting in an autocrine manner. Finally, WISP1-induced MIF promoted the expression of cyclooxygenase 2, prostaglandin E2, IL-6, and matrix metalloproteinase-2 demonstrating the regulatory role of WISP1-MIF axis in lung inflammation and remodeling involving mainly integrin αvβ5, Src kinases, PKC, NF-κB, and EGFR. The specific signaling pathways involved in WISP1-induced expression of MIF may prove to be excellent candidates for novel targets to control inflammation in chronic lung diseases.NEW & NOTEWORTHY The present study demonstrates for the first time that Wnt1-inducible signaling protein 1 (WISP1) regulates migration inhibitory factor (MIF) expression and activity and identifies the main signaling pathways involved. The newly discovered WISP1-MIF axis may drive lung inflammation and could result in the design of novel targeted therapies in inflammatory lung diseases.

Crosstalk with lung fibroblasts shapes the growth and therapeutic response of mesothelioma cells

Mesothelioma is an aggressive cancer of the mesothelial layer associated with an extensive fibrotic response. The latter is in large part mediated by cancer-associated fibroblasts which mediate tumour progression and poor prognosis. However, understanding of the crosstalk between cancer cells and fibroblasts in this disease is mostly lacking. Here, using co-cultures of patient-derived mesothelioma cell lines and lung fibroblasts, we demonstrate that fibroblast activation is a self-propagated process producing a fibrotic extracellular matrix (ECM) and triggering drug resistance in mesothelioma cells. Following characterisation of mesothelioma cells/fibroblasts signalling crosstalk, we identify several FDA-approved targeted therapies as far more potent than standard-of-care Cisplatin/Pemetrexed in ECM-embedded co-culture spheroid models. In particular, the SRC family kinase inhibitor, Saracatinib, extends overall survival well beyond standard-of-care in a mesothelioma genetically-engineered mouse model. In short, we lay the foundation for the rational design of novel therapeutic strategies targeting mesothelioma/fibroblast communication for the treatment of mesothelioma patients.

Characterization of the soft-tissue wall lining residual periodontal pockets and implications in periodontal wound healing

AIM

To characterize the soft-tissue wall of remaining periodontal pockets for wound healing-related parameters versus healthy gingival crevices in the same individuals.

MATERIALS AND METHODS

Gingival tissues collected from the diseased interface of pockets (GT biopsies) and from healthy gingival crevices (G biopsies) were subjected to RT2-profiler PCR Array for wound healing-related markers and network analysis of differentially expressed genes. Lymphangiogenesis-related gene expression was determined by qRT-PCR. The migration potential of mesenchymal stem cells isolated from GT biopsies (GT-MSCs) and G biopsies (G-MSCs) was evaluated by the scratch- and the transwell migration assays. The total collagen protein content was determined in GT-MSCs and G-MSCs homogenates.

RESULTS

Gene-ontology analysis on significantly upregulated genes expressed in GT biopsies revealed enrichment of several genes involved in processes related to matrix remodeling, collagen deposition, and integrin signaling. No significantly expressed genes were seen in G biopsies. Regarding lymphangiogenesis-related genes, GT biopsies demonstrated greater expression for PROX1 than G biopsies (p = 0.05). Lower migration potential (p < 0.001), yet greater production of collagen protein (p = 0.05), was found for GT-MSCs over G-MSCs.

CONCLUSION

Differential expression patterns of various molecular pathways in biopsies and cell cultures of diseased versus healthy gingival tissues indicate a potential of the former for tissue remodeling and repair.

CLINICAL RELEVANCE

In the course of periodontitis, granulation tissue is formed within a periodontal defect in an attempt to reconstruct the site. Following treatment procedures periodontal granulation tissue remains inflamed but appears to retain healing potential.

Fibroblasts at the curtain call: from ensemble to principal dancers in immunometabolism and inflammaging

Inflammation is a necessary step in response to injuries, being vital in restoring homeostasis and facilitating tissue healing. Among the cells that play a crucial role in inflammatory responses, stromal cells, including fibroblasts, have an undeniable significance in fine-tuning the magnitude of mediators that directly affect hyper-inflammatory responses and tissue destruction. Fibroblasts, the dominant cells in the gingival connective tissue, are a very heterogeneous population of cells, and more recently they have been receiving well deserved attention as central players and often the 'principal dancers' of many pathological processes ranging from inflammation and fibrosis to altered immunity and cancer. The goal of the current investigation is to dive into the exact role of the stromal fibroblast and the responsible mechanistic factors involved in both regulation and dysregulation of the inflammatory responses. This article reviews the most recent literature on how fibroblasts, in their different activation states or subtypes, play a crucial role in contributing to inflammatory outcomes. We will focus on recent findings on inflammatory diseases. We will also provide connections regarding the stromal-immune relationship, which supports the idea of fibroblast coming out from the 'ensemble' of cell types to the protagonist role in immunometabolism and inflammaging. Additionally, we discuss the current advances in variation of fibroblast nomenclature and division into clusters with their own suggested function and particularities in gene expression. Here, we provide a perspective for the periodontal implications, discussing the fibroblast role in the infection-driven and inflammatory mediated diseases such as periodontitis.

Wound healing in aged skin exhibits systems-level alterations in cellular composition and cell-cell communication

Delayed and often impaired wound healing in the elderly presents major medical and socioeconomic challenges. A comprehensive understanding of the cellular/molecular changes that shape complex cell-cell communications in aged skin wounds is lacking. Here, we use single-cell RNA sequencing to define the epithelial, fibroblast, immune cell types, and encompassing heterogeneities in young and aged skin during homeostasis and identify major changes in cell compositions, kinetics, and molecular profiles during wound healing. Our comparative study uncovers a more pronounced inflammatory phenotype in aged skin wounds, featuring neutrophil persistence and higher abundance of an inflammatory/glycolytic Arg1^Hi macrophage subset that is more likely to signal to fibroblasts via interleukin (IL)-1 than in young counterparts. We predict systems-level differences in the number, strength, route, and signaling mediators of putative cell-cell communications in young and aged skin wounds. Our study exposes numerous cellular/molecular targets for functional interrogation and provides a hypothesis-generating resource for future wound healing studies.

The Role of Macrophage Migration Inhibitory Factor in Adipose-Derived Stem Cells Under Hypoxia

Background: Adipose-derived stem cells (ASCs) are multipotent mesenchymal stem cells characterized by their strong regenerative potential and low oxygen consumption. Macrophage migration inhibitory factor (MIF) is a multifunctional chemokine-like cytokine that is involved in tissue hypoxia. MIF is not only a major immunomodulator but also is highly expressed in adipose tissue such as subcutaneous adipose tissue of chronic non-healing wounds. In the present study, we investigated the effect of hypoxia on MIF in ASCs isolated from healthy versus inflamed adipose tissue. Methods: Human ASCs were harvested from 17 patients (11 healthy adipose tissue samples, six specimens from chronic non-healing wounds). ASCs were treated in a hypoxia chamber at <1% oxygen. ASC viability, MIF secretion as well as expression levels of MIF, its receptor CD74, hypoxia-inducible transcription factor-1α (HIF-1α) and activation of the AKT and ERK signaling pathways were analyzed. The effect of recombinant MIF on the viability of ASCs was determined. Finally, the effect of MIF on the viability and production capacity of ASCs to produce the inflammatory cytokines tumor necrosis factor (TNF), interleukin (IL)-6, and IL-1β was determined upon treatment with recombinant MIF and/or a blocking MIF antibody. Results: Hypoxic treatment inhibited proliferation of ASCs derived from healthy or chronic non-healing wounds. ASCs from healthy adipose tissue samples were characterized by a low degree of MIF secretion during hypoxic challenge. In contrast, in ASCs from adipose tissue samples of chronic non-healing wounds, secretion and expression of MIF and CD74 expression were significantly elevated under hypoxia. This was accompanied by enhanced ERK signaling, while AKT signaling was not altered. Recombinant MIF did stimulate HIF-1α expression under hypoxia as well as AKT and ERK phosphorylation, while no effect on ASC viability was observed. Recombinant MIF significantly reduced the secretion of IL-1β under hypoxia and normoxia, and neutralizing MIF-antibodies diminished TNF-α and IL-1β release in hypoxic ASCs. Conclusions: Collectively, MIF did not affect the viability of ASCs from neither healthy donor site nor chronic wounds. Our results, however, suggest that MIF has an impact on the wound environment by modulating inflammatory factors such as IL-1β.

Extracellular MIF, but not its homologue D-DT, promotes fibroblast motility independently of its receptor complex CD74/CD44

Macrophage migration inhibitory factor (MIF) and its homologue D-dopachrome tautomerase (D-DT) are widely expressed pro-inflammatory cytokines with chemokine-like functions that coordinate a wide spectrum of biological activities, such as migration. Here, we biotin-tagged intracellular MIF/D-DT in vivo to identify important cytosolic interactors and found a plethora of actin cytoskeleton-associated proteins. Although the receptor complex between CD74 and CD44 (CD74/CD44) is essential for signalling transduction in fibroblasts via extracellular MIF/D-DT, our interactome data suggested direct effects. We, thus, investigated whether MIF/D-DT can modulate cell migration independently of CD74/CD44. To distinguish between receptor- and non-receptor-mediated motility, we used fibroblasts that are either deficient or that express CD74/CD44 proteins, and treated them with recombinant MIF/D-DT. Interestingly, only MIF could stimulate chemokinesis in the presence or absence of CD74/CD44. The pro-migratory effects of MIF depended on lipid raft/caveolae-mediated but not clathrin-mediated endocytosis, on its tautomerase activity and, probably, on its thiol protein oxidoreductase activity. As MIF treatment restrained actin polymerisation in vitro, our findings establish a new intracellular role for MIF/D-DT in driving cell motility through modulation of the actin cytoskeleton.

Characterization and expression of macrophage migration inhibitory factor (mif) in Chinese sturgeon (Acipenser sinensis)

The Chinese sturgeon (Acipenser sinensis) is one of the critically endangered aquatic species in China. It is also among the oldest extant actinopterygian fish species. To advance the characterization of the Chinese sturgeon immune system, we identified the gene encoding the macrophage migration inhibitory factor (MIF), a multifunctional cytokine that contributes to both innate and adaptive immune responses. Molecular and phylogenic analysis indicates the Chinese sturgeon (cs) MIF share a high degree of structural conservation with other MIF sequences and is closely related to other bony fish MIF. At steady state, cs-mif gene is expressed at relatively high levels in the brain, and to a lesser but significant level in liver, spleen, kidney, gut and skin. The spatial expression patterns determined by in situ hybridization indicates a preferential distribution of cs-mif transcripts in the cerebral cortex, the gut epithelium, hematopoietic tissues of kidney, spleen and liver parenchyma, and skin epidermis. Marked increase of cs-mif gene expression was induced by lipopolysaccharide (LPS) stimulation and Aeromonas hydrophila infection in all tested tissues. Furthermore, higher cs-mif transcript levels were detected in the liver, spleen, kidney, gut and skin during stress response resulting from hyperthermia. These results are not only consistent with the expected role of cs-mif gene in innate immunity but also suggest a potential role of this gene in stress response to hyperthermia in the Chinese sturgeon.

The effect of the macrophage migration inhibitory factor (MIF) on excisional wound healing in vivo

Background: The macrophage migration inhibitory factor (MIF) has been determined as a cytokine exerting a multitude of effects in inflammation and angiogenesis. Earlier studies have indicated that MIF may also be involved in wound healing and flap surgery. Methods: We investigated the effect of MIF in an excisional wound model in wildtype, Mif^-/- and recombinant MIF treated mice. Wound closure rates as well as the macrophage marker Mac-3, the pro-inflammatory cytokine tumor necrosis factor α (TNFα) and the pro-angiogenic factor von Willebrand factor (vWF) were measured. Finally, we used a flap model in Mif^-/- and WT mice with an established perfusion gradient to identify MIF's contribution in flap perfusion. Results: In the excision wound model, we found reduced wound healing after MIF injection, whereas Mif deletion improved wound healing. Furthermore, a reduced expression of Mac-3, TNFα and vWF in Mif^-/- mice was seen when compared to WT mice. In the flap model, Mif^-/- knockout mice showed mitigated flap perfusion with lower hemoglobin content and oxygen saturation as measured by O₂C measurements when compared to WT mice. Conclusions: Our data suggest an inhibiting effect of MIF in wound healing with increased inflammation and perfusion. In flaps, by contrast, MIF may contribute to flap vascularization.

Early biological responses in ocular tissue after SMILE and LASIK surgery

We studied the early protein profile in the ocular tissue extracted after LASIK and SMILE surgery. SMILE and LASIK was performed in contralateral eyes and stromal tissue samples were collected from 10 eyes of 5 donors. The stromal tissue samples were analyzed using label free quantification approach and ITRAQ labelling approach in LC-MS/MS. Combined functional analysis revealed many differentially expressed proteins which were involved in important biological processes. About 117 unique differentially expressed proteins were identified using two different proteomic approaches. Collagens, proteoglycans, corneal crystallins were enriched and showed differential expression in SMILE and LASIK as compared to the non-surgical control. Apart from these, 14-3-3 class of proteins, Lysozyme (LYZ), Macrophage Migratory Inhibitory Factor protein (MIF), Pigment Epithelial Derived Factor (PEDF) were differentially expressed when compared between LASIK and SMILE. Peroxiredoxin 1 (PRDX1) expression was found to be reduced in LASIK as compared to SMILE. The expression of Lysozyme C and Macrophage Migratory Inhibitory Factor inflammatory response was found to be less in SMILE as compared to LASIK. Western blot validation of specific markers such as Collagen IV (COL4), Keratocan (KERA), Lumican (LUM), Aldehyde dehydrogenase 3 A1 (ALDH3A1), Lysozyme C (LYZC) confirmed the differences in the protein levels observed in SMILE and LASIK operated tissues as compared to non-surgical controls. In conclusion, this study revealed the early molecular changes occurring in the cornea resulting from these two surgical procedures which may have implications on managing post-operative complications.

Multiple roles of macrophage migration inhibitory factor in pulmonary hypertension

Pulmonary hypertension (PH) is a life-threatening condition arising from the loss and obstructive remodeling of the pulmonary arteries, leading to the sustained elevation of pulmonary arterial pressure (PAP) and pulmonary vascular resistance (PVR) and subsequently right ventricular (RV) failure and death. PH encompasses a group of multifactorial diseases, such as pulmonary arterial hypertension (PAH) and chronic thromboembolic PH, for which there is no treatment that can stop or reverse the progression of remodeling of the pulmonary vasculature. The identification of new molecular targets for the development of more effective drugs is thus urgently needed. In this context, macrophage migration inhibitory factor (MIF), a pleiotropic upstream proinflammatory mediator, is emerging as a promising molecular target, as it contributes to perivascular inflammation and pulmonary arterial remodeling, two key hallmarks of PAH that are not specifically targeted by currently approved therapies. The objective of this review is to summarize the scientific evidence on the pathogenic roles of MIF and its potential as a biomarker and therapeutic target in PH/PAH.

The Proinflammatory and Proangiogenic Macrophage Migration Inhibitory Factor Is a Potential Regulator in Proliferative Diabetic Retinopathy

The macrophage migration inhibitory factor (MIF)/CD74 signaling pathway is strongly implicated in inflammation and angiogenesis. We investigated the expression of MIF and its receptor CD74 in proliferative diabetic retinopathy (PDR) to reveal a possible role of this pathway in the pathogenesis of PDR. Levels of MIF, soluble (s)CD74, soluble intercellular adhesion molecule-1 (sICAM-1) and vascular endothelial growth factor (VEGF) were significantly increased in the vitreous from patients with PDR compared to nondiabetic control samples. We detected significant positive correlations between the levels of MIF and the levels of sICAM-1 (r = 0.43; p = 0.001) and VEGF (r = 0.7; p < 0.001). Through immunohistochemical analysis of PDR epiretinal membranes, significant positive correlations were also found between microvessel density (CD31 expression) and the numbers of blood vessels expressing MIF (r = 0.56; p = 0.045) and stromal cells expressing MIF (r = 0.79; p = 0.001) and CD74 (r = 0.59; p = 0.045). Similar to VEGF, MIF was induced in Müller cells cultured under hypoxic conditions and MIF induced phosphorylation of ERK1/2 and VEGF production in Müller cells. Intravitreal administration of MIF in normal rats induced increased retinal vascular permeability and significant upregulation of phospho-ERK1/2, NF-κB, ICAM-1 and vascular cell adhesion molecule-1 expression in the retina. MIF induced migration and proliferation of human retinal microvascular endothelial cells. These results suggest that MIF/CD74 signaling is involved in PDR angiogenesis.

5-HT1A Receptor Function Makes Wound Healing a Happier Process

Skin wound healing is a multistage phenomenon that is regulated by cell–cell interplay and various factors. Endogenous serotonin is an important neurotransmitter and cytokine. Its interaction with the serotonin 1A receptor (5-HTR1A) delivers downstream cellular effects. The role of serotonin (5-hydroxytryptamine, 5-HT) and the 5-HT1A receptor has been established in the regeneration of tissues such as the liver and spinal motor neurons, prompting the investigation of the role of 5-HT1A receptor in skin healing. This study assessed the role of 5-HT1A receptor in excisional wound healing by employing an excisional punch biopsy model on 5-Ht1a receptor knockout mice. Post-harvest analysis revealed 5-Ht1a receptor knockout mice showed impaired skin healing, accompanied by a greater number of F4/80 macrophages, which prolongs the inflammatory phase of wound healing. To further unravel this phenomenon, we employed the 5-HT1A receptor agonist [(R)-(+)-8-Hydroxy-DPAT hydrobromide] as a topical cream treatment in an excisional punch biopsy model. The 5-HT1A receptor agonist treated group showed a smaller wound area, scar size, and improved neovascularization, which contributed to improve healing outcomes as compared to the control. Collectively, these findings revealed that serotonin and 5-HT1A receptor play an important role during the healing process. These findings may open new lines of investigation for the potential treatment alternatives to improve skin healing with minimal scarring.

Macrophage migration inhibitory factor (MIF) in the development and progression of pulmonary arterial hypertension

Macrophage migration inhibitory factor (MIF) has been described as a pro-inflammatory cytokine and regulator of neuro-endocrine function. It plays an important upstream role in the inflammatory cascade by promoting the release of other inflammatory cytokines such as TNF-alpha and IL-6, ultimately triggering a chronic inflammatory immune response. As lungs can synthesize and release MIF, many studies have investigated the potential role of MIF as a biomarker in assessment of patients with pulmonary arterial hypertension (PAH) and using anti-MIFs as a new therapeutic modality for PAH.

Roles of macrophage migration inhibitory factor in Guillain-Barré syndrome and experimental autoimmune neuritis: beneficial or harmful?

INTRODUCTION

Macrophage migration inhibitory factor (MIF) plays an important role in the pathogenesis of Guillain-Barré syndrome (GBS) and its animal model experimental autoimmune neuritis (EAN), which may offer an opportunity for the development of the novel therapeutic strategies for GBS. Areas covered: 'macrophage migration inhibitory factor' and 'Guillain-Barré syndrome' were used as keywords to search for related publications on Pub-Med, National Center for Biotechnology Information (NCBI), USA. MIF is involved in the etiology of various inflammatory and autoimmune disorders. However, the roles of MIF in GBS and EAN have not been summarized in the publications we identified. Therefore, in this review, we described and analyzed the major roles of MIF in GBS/EAN. Primarily, this molecule aggravates the inflammatory responses in this disorder. However, multiple studies indicated a protective role of MIF in GBS. The potential of MIF as a therapeutic target in GBS has been recently demonstrated in experimental and clinical studies, although clinical trials have been unavailable to date. Expert opinion: MIF plays a critical role in the initiation and progression of GBS and EAN, and it may represent a potential therapeutic target for GBS.

Influence of white matter injury on gray matter reactive gliosis upon stab wound in the adult murine cerebral cortex

Traumatic brain injury frequently affects the cerebral cortex, yet little is known about the differential effects that occur if only the gray matter (GM) is damaged or if the injury also involves the white matter (WM). To tackle this important question and directly compare similarities and differences in reactive gliosis, we performed stab wound injury affecting GM and WM (GM+) and one restricted to the GM (GM-) in the adult murine cerebral cortex. First, we examined glial reactivity in the regions affected (WM and GM) and determined the influence of WM injury on reactive gliosis in the GM comparing the same area in the two injury paradigms. In the GM+ injury microglia proliferation is increased in the WM compared with GM, while proliferating astrocytes are more abundant in the GM than in the WM. Interestingly, WM lesion exerted a strong influence on the proliferation of the GM glial cells that was most pronounced at early stages, 3 days post lesion. While astrocyte proliferation was increased, NG2 glia proliferation was decreased in the GM+ compared with GM- lesion condition. Importantly, these differences were not observed when a lesion of the same size affected only the GM. Unbiased proteomic analyses further corroborate our findings in support of a profound difference in GM reactivity when WM is also injured and revealed MIF as a key regulator of NG2 glia proliferation.

Characterization of extracellular vesicles derived from cardiac cells in an in vitro model of preconditioning

Preconditioning is a promising technique to protect the heart from ischaemia-reperfusion injury. In this context, the crosstalk between different cardiac cell types and especially the exchange of cardioprotective mediators has come into the focus of current research. Recently, extracellular vesicles (EVs), nano-sized structures, emerged as possible communication mediators. They are taken up by recipient cells and can alter gene expression or activate intracellular signal cascades. It has been shown that all cardiac cell types are able to secrete EVs, but so far the influence of an in vitro preconditioning stimulus on EV concentration and composition has not been investigated. Therefore, we stimulated primary cardiac myocytes and fibroblasts from neonatal rats, as well as H9c2 cells, with two known in vitro preconditioning stimuli: hypoxia or isoflurane. EVs were isolated from cell culture supernatants 48 h after stimulation by differential centrifugation and size exclusion chromatography. They were characterized by transmission electron microscopy, tunable resistive pulse sensing, miRNA array and Western blot analysis. The detected EVs had the typical cup-shaped morphology and a size of about 150 nm. No significant differences in EV concentration were observed between the different groups. The protein and miRNA load was affected by in vitro preconditioning with isoflurane or hypoxia. EV markers like Alix, CD63, flotillin-1 and especially heat shock protein 70 were significantly up-regulated by the treatments. Several miRNAs like miR-92b-3p, miR-761 and miR-101a-5p were also significantly affected. A migration assay confirmed the physiological benefit of these EVs. Taken together, our findings show that a model of in vitro preconditioning of cardiac cells does not influence EV concentration but strongly regulates the EV cargo and affects migration. This might indicate a role for EV-mediated communication in isoflurane- and hypoxia-induced in vitro preconditioning.

Specific recruitment of circulating angiogenic cells using biomaterials as filters

Endogenous recruitment of circulating angiogenic cells (CACs) is an emerging strategy to induce angiogenesis within a defect site, and multiple recent strategies have deployed soluble protein releasing biomaterials for this purpose. However, the way in which the design of biomaterials affects CAC recruitment and invasion are poorly understood. Here we used an enhanced-throughput cell invasion assay to systematically examine the effects of biomaterial design on CAC recruitment. The screens co-optimized hydrogel presentation of a stromal-derived factor-1α (SDF-1α) gradient, hydrogel degradability, and hydrogel stiffness for maximal CAC invasion. We also examined the specificity of this invasion by assessing dermal fibroblast, mesenchymal stem cell, and lymphocyte invasion individually and in co-culture with CACs to identify hydrogels specific to CAC invasion. These screens suggested a subset of MMP-degradable hydrogels presenting a specific range of SDF-1α gradient slopes that induced specific invasion of CACs, and we posit that the design parameters of this subset of hydrogels may serve as instructive templates for the future design of biomaterials to specifically recruit CACs. We also posit that this design concept may be applied more broadly in that it may be possible to utilize these specific subsets of biomaterials as "filters" to control which types of cell populations invade into and populate the biomaterial.

STATEMENT OF SIGNIFICANCE

The recruitment of specific cell types for cell-based therapies in vivo is of great interest to the regenerative medicine community. Circulating angiogenic cells (CACs), CD133+ cells derived from the blood stream, are of particular interest for induction of angiogenesis in ischemic tissues, and recent studies utilizing soluble-factor releasing biomaterials to recruit these cells in vivo show great promise. However, these studies are largely "proof of concept" and are not systematic in nature. Thus, little is currently known about how biomaterial design affects the recruitment of CACs. In the present work, we use a high throughput cell invasion screening platform to systematically examine the effects of biomaterial design on circulating angiogenic cell (CAC) recruitment, and we successfully screened 263 conditions at 3 replicates each. Our results identify a particular subset of conditions that robustly recruit CACs. Additionally, we found that these conditions also specifically recruited CACs and excluded the other tested cells types of dermal fibroblasts, mesenchymal stem cells, and lymphocytes. This suggests an intriguing new role for biomaterials as "filters" to control the types of cells that invade and populate that biomaterial.

D-dopachrome tautomerase in adipose tissue inflammation and wound repair

D-dopachrome tautomerase (D-DT/MIF-2) is a member of the macrophage migration inhibitory factor (MIF) cytokine superfamily, and a close structural homolog of MIF. MIF and D-DT have been reported to be involved in obesity, but there is little known about the regulation of D-DT in adipose tissue inflammation and wound healing. Subcutaneous adipose tissue was collected from 54 healthy donors and 28 donors with acutely inflamed wounds undergoing wound debridement. In addition, epididymal fat pads of mice were injected with lipopolysaccharide to study receptor expression and cell migration in vivo. D-DT protein levels and mRNA expression were significantly decreased in subcutaneous adipose tissue adjacent to acutely inflamed wounds. D-DT improved fibroblast viability and increased proliferation in vitro. While D-DT alone did not have a significant effect on in vitro fibroblast wound healing, simultaneous addition of neutralizing MIF antibody resulted in a significant improvement of fibroblast wound healing. Interestingly, expression of the MIF and D-DT receptor CD74 was down-regulated while the MIF receptors CXCR2 and CXCR4 were up-regulated primarily on macrophages indicating that the MIF-CXCR2/4 axis may promote recruitment of inflammatory cells into adipose tissue. Our results describe a reciprocal role of D-DT to MIF in inflamed adipose tissue, and indicate that D-DT may be beneficial in wound repair by improving fibroblast survival and proliferation.

The Effect of Lipoaspirates on Human Keratinocytes

BACKGROUND

One increasingly important trend in plastic, reconstructive, and aesthetic surgery is the use of fat grafts to improve cutaneous wound healing. In clinical practice, lipoaspirates (adipose tissue harvested by liposuction) are re-injected in a procedure called lipofilling. Previous studies, however, mainly evaluated the regenerative effect of isolated adipocytes, adipose-derived stem cells, and excised en bloc adipose tissue on keratinocytes, whereas no study to date has examined the effect of lipoaspirates.

OBJECTIVES

The authors aimed to investigate differences in the regenerative property of en bloc adipose tissue and lipoaspirates on keratinocytes.

METHODS

Human keratinocytes, lipoaspirates, and en bloc adipose tissue from 36 healthy donors were isolated. In vitro proliferation, differentiation, migration, stratification, and wound healing of keratinocyte monolayers were measured. Furthermore, secreted levels of VEGF, bFGF, IGF-1, MMP-9, and MIF were detected by ELISA.

RESULTS

Migration, proliferation, and wound healing of keratinocytes were increased by lipoaspirates. Interestingly, the effect of lipoaspirates on keratinocyte proliferation was significantly higher than by en bloc adipose tissue after 5 days. The differentiation of keratinocytes was equally attenuated by lipoaspirates and en bloc adipose tissue. Stratification of keratinocyte layers was enhanced by lipoaspirates and en bloc fat when compared to controls. Lipoaspirates secrete higher levels of bFGF, whereas higher levels of VEGF and IGF-1 are released by en bloc adipose tissue.

CONCLUSION

We show that lipoaspirates and en bloc adipose tissue have a regenerative effect on keratinocytes. One reason for the higher effect of lipoaspirates on keratinocyte proliferation may be the secretion of different cytokines.

Macrophage Migration Inhibitory Factor in Acute Adipose Tissue Inflammation

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine and has been implicated in inflammatory diseases. However, little is known about the regulation of MIF in adipose tissue and its impact on wound healing. The aim of this study was to investigate MIF expression in inflamed adipose and determine its role in inflammatory cell recruitment and wound healing. Adipose tissue was harvested from subcutaneous adipose tissue layers of 24 healthy subjects and from adipose tissue adjacent to acutely inflamed wounds of 21 patients undergoing wound debridement. MIF protein and mRNA expression were measured by ELISA and RT-PCR. Cell-specific MIF expression was visualized by immunohistochemistry. The functional role of MIF in cell recruitment was investigated by a chemotaxis assay and by flow cytometry of labeled macrophages that were injected into Mif^–/–and wildtype mice. Wound healing was evaluated by an in vitro scratch assay on human fibroblast monolayers. MIF protein levels of native adipose tissue and supernatants from acutely inflamed wounds were significantly elevated when compared to healthy controls. MIF mRNA expression was increased in acutely inflamed adipose tissue indicating the activation of MIF gene transcription in response to adipose tissue inflammation. MIF is expressed in mature adipocytes and in infiltrated macrophages. Peripheral blood mononuclear cell migration was significantly increased towards supernatants derived from inflamed adipose tissue. This effect was partially abrogated by MIF-neutralizing antibodies. Moreover, when compared to wildtype mice, Mif^–/–mice showed reduced infiltration of labeled macrophages into LPS-stimulated epididymal fat pads in vivo. Finally, MIF antibodies partially neutralized the detrimental effect of MIF on fibroblast wound healing. Our results indicate that increased MIF expression and rapid activation of the MIF gene in fat tissue adjacent to acute wound healing disorders may play a role in cell recruitment to the site of inflammation and wound healing.

Chronic macrophage migration inhibitory factor exposure induces mesenchymal epithelial transition and promotes gastric and colon cancers

Macrophage Migration Inhibitory Factor (MIF) is an inflammatory cytokine that is highly produced in gastrointestinal cancers. Since chronic inflammation is a risk factor for tumorigenesis in these cancers, in this study, the role of MIF in pro-tumorigenic events was examined. MIF and its receptor, CD74, were examined in gastric and colon tumors and found to be increased in most tumors with significantly higher expression in tumors from patients with lymph node metastasis. MIF was also found to be highly produced by cancer associated fibroblasts isolated from human tumors compared to fibroblasts from matched normal tissues from uninvolved areas. Fibroblast-produced MIF highly increased GI cancer cell proliferation, which was decreased upon neutralizing MIF or CD74. Chronic MIF treatment led to sustained proliferation and signaling events in non-transformed GI fibroblast cells, which was maintained upon removing MIF treatment for 8 weeks. Additionally, chronic treatment of normal GI cells expressing fibroblast markers for up to 16 weeks with MIF led to a drastic decrease of fibroblast markers with concurrent increase of epithelial markers. Transformation was examined by telomerase and focus forming assays. These results suggest the MIF promotes mesenchymal epithelial transition, cell transformation and tumorigenesis in GI cancers, and thus may be an important link between chronic inflammation and tumorigenesis.

MIF promotes B cell chemotaxis through the receptors CXCR4 and CD74 and ZAP-70 signaling

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine with chemokine-like functions that plays a pivotal role in the pathogenesis of inflammatory diseases by promoting leukocyte recruitment. We showed that MIF promotes the atherogenic recruitment of monocytes and T cells through its receptors CXCR2 and CXCR4. Effects of MIF on B cell recruitment have not been addressed. In this study, we tested the involvement of MIF in B cell chemotaxis and studied the underlying mechanism. We show that MIF promotes primary murine B cell chemotaxis in a dose-dependent manner, comparable to the B cell chemokines CXCL13 and CXCL12. Splenic B cells express CXCR4 and the receptor CD74 but not CXCR2. Inhibition of CXCR4 or CD74 or a genetic deficiency of Cd74 in primary B cells fully abrogated MIF-mediated B cell migration, implying cooperative involvement of both receptors. MIF stimulation of B cells resulted in a rapid increase in intracellular Ca(2+) mobilization and F-actin polymerization. Intriguingly, the tyrosine kinase ZAP-70 was activated upon MIF and CXCL12 treatment in a CXCR4- and CD74-dependent manner. Pharmacological inhibition of ZAP-70 resulted in abrogation of primary B cell migration. Functional involvement of ZAP-70 was confirmed by small interfering RNA-mediated knockdown in Ramos B cell migration. Finally, primary B cells from ZAP-70 gene-deficient mice exhibited ablated transmigration in response to MIF or CXCL12. We conclude that MIF promotes the migration of B cells through a ZAP-70-dependent pathway mediated by cooperative engagement of CXCR4 and CD74. The data also suggest that MIF may contribute to B cell recruitment in vivo (e.g., in B cell-related immune disorders).

Role of migratory inhibition factor in age-related susceptibility to radiation lung injury via NF-E2-related factor-2 and antioxidant regulation

Microvascular injury and increased vascular leakage are prominent features of radiation-induced lung injury (RILI), and often follow cancer-associated thoracic irradiation. Our previous studies demonstrated that polymorphisms in the gene (MIF) encoding macrophage migratory inhibition factor (MIF), a multifunctional pleiotropic cytokine, confer susceptibility to acute inflammatory lung injury and increased vascular permeability, particularly in senescent mice. In this study, we exposed wild-type and genetically engineered mif(-/-) mice to 20 Gy single-fraction thoracic radiation to investigate the age-related role of MIF in murine RILI (mice were aged 8 wk, 8 mo, or 16 mo). Relative to 8-week-old mice, decreased MIF was observed in bronchoalveolar lavage fluid and lung tissue of 8- to 16-month-old wild-type mice. In addition, radiated 8- to 16-month-old mif(-/-) mice exhibited significantly decreased bronchoalveolar lavage fluid total antioxidant concentrations with progressive age-related decreases in the nuclear expression of NF-E2-related factor-2 (Nrf2), a transcription factor involved in antioxidant gene up-regulation in response to reactive oxygen species. This was accompanied by decreases in both protein concentrations (NQO1, GCLC, and heme oxygenase-1) and mRNA concentrations (Gpx1, Prdx1, and Txn1) of Nrf2-influenced antioxidant gene targets. In addition, MIF-silenced (short, interfering RNA) human lung endothelial cells failed to express Nrf2 after oxidative (H2O2) challenge, an effect reversed by recombinant MIF administration. However, treatment with an antioxidant (glutathione reduced ester), but not an Nrf2 substrate (N-acetyl cysteine), protected aged mif(-/-) mice from RILI. These findings implicate an important role for MIF in radiation-induced changes in lung-cell antioxidant concentrations via Nrf2, and suggest that MIF may contribute to age-related susceptibility to thoracic radiation.

Toll-Like Receptor 4 (TLR4) expression and stimulation in a model of intervertebral disc inflammation and degeneration

STUDY DESIGN

We measured the expression and responses of Toll-Like Receptor 4 (TLR4) activation in the intervertebral disc (IVD) in vitro and in vivo. We hypothesize that stimulation of the IVD with the TLR4 ligand lipopolysaccharide (LPS) results in upregulation of a coordinated set of proinflammatory mediators and inhibition of matrix expression, both consistent with a molecular profile of degeneration.

OBJECTIVE

To characterize early inflammatory and morphological changes induced by TLR4 activation in the IVD.

SUMMARY OF BACKGROUND DATA

TLR4 is a pattern recognition receptor activated in innate immunity that has been implicated in disease mechanisms of inflammatory cartilaginous degeneration. However, no study to date has examined the expression and responses of TLR4 in the IVD.

METHODS

IVD cells were stimulated with LPS in a dose-dependent manner, and inflammatory cytokine levels were measured by quantitative reverse transcription-polymerase chain reaction. Histological and inflammatory changes due to in vivo injection of LPS into the rat caudal IVD were measured by enzyme-linked immunosorbent assay and immunoblotting.

RESULTS

Baseline TLR4 expression in IVD tissue varied according to cell type. LPS stimulation resulted in significant increases in tumor necrosis factor α (TNF)-α, interleukin (IL)-1β, IL-6, and nitric oxide levels and significant inhibition in aggrecan and collagen-2. Intradiscal injection of LPS was found to cause moderate degenerative changes in the IVD, with increases in tissue levels of IL-1β, TNF-α, high mobility group box 1 protein (HMGB1), and macrophage migration inhibitory factor (MIF).

CONCLUSION

This study provides the first evidence that IVD cells express TLR4 and are responsive to TLR4 activation by upregulating a coordinated set of inflammatory cytokines. This study suggests that intradiscal injection of LPS offers a model for triggering inflammation of the IVD, demonstrating that inflammatory insults alone may potentially trigger degenerative changes of the IVD.

Differential roles of angiogenic chemokines in endothelial progenitor cell-induced angiogenesis

This study aimed to analyze the role of endothelial progenitor cell (EPC)-derived angiogenic factors and chemokines in the multistep process driving angiogenesis with a focus on the recently discovered macrophage migration inhibitory factor (MIF)/chemokine receptor axis. Primary murine and murine embryonic EPCs (eEPCs) were analyzed for the expression of angiogenic/chemokines and components of the MIF/CXC chemokine receptor axis, focusing on the influence of hypoxic versus normoxic stimulation. Hypoxia induced an upregulation of CXCR2 and CXCR4 but not CD74 on EPCs and triggered the secretion of CXCL12, CXCL1, MIF, and vascular endothelial growth factor (VEGF). These factors stimulated the transmigration activity and adhesive capacity of EPCs, with MIF and VEGF exhibiting the strongest effects under hypoxia. MIF-, VEGF-, CXCL12-, and CXCL1-stimulated EPCs enhanced tube formation, with MIF and VEGF exhibiting again the strongest effect following hypoxia. Tube formation following in vivo implantation utilizing angiogenic factor-loaded Matrigel plugs was only promoted by VEGF. Coloading of plugs with eEPCs led to enhanced tube formation only by CXCL12, whereas MIF was the only factor which induced differentiation towards an endothelial and smooth muscle cell (SMC) phenotype, indicating an angiogenic and differentiation capacity in vivo. Surprisingly, CXCL12, a chemoattractant for smooth muscle progenitor cells, inhibited SMC differentiation. We have identified a role for EPC-derived proangiogenic MIF, VEGF and MIF receptors in EPC recruitment following hypoxia, EPC differentiation and subsequent tube and vessel formation, whereas CXCL12, a mediator of early EPC recruitment, does not contribute to the remodeling process. By discerning the contributions of key angiogenic chemokines and EPCs, these findings offer valuable mechanistic insight into mouse models of angiogenesis and help to define the intricate interplay between EPC-derived angiogenic cargo factors, EPCs, and the angiogenic target tissue.

Macrophage migration inhibitory factor is elevated in obese adolescents

OBJECTIVES

The prevalence of obesity in childhood and adolescence is continuing rising. Macrophage migration inhibitory factor (MIF) participates in inflammatory and immune responses as a pro-inflammatory cytokine. The present study aimed to investigate MIF in overweight adolescents.

METHODS

Seventy-nine male adolescents were enrolled. Thirty-eight were overweight according to the 90th%ile of the age-specific waist circumference. Various parameters were recorded at one visit, including body mass index. MIF was determined using multiplex immune-assay technology.

RESULTS

Overweight adolescents had increased systolic blood pressure and CRP levels. Furthermore, increased circulating MIF concentrations were observed (Median: 964.6 pg/ml, Interquartile range: 590.3-2019.4 versus Median: 562.7 pg/ml, Interquartile range: 430.6-813.7, p = 0.003). Increased MIF concentrations were associated with increased markers of inflammation and obesity.

CONCLUSIONS

We demonstrated elevated MIF levels in obese adolescents. Taken together with other markers, this indicates the presence of low-grade inflammation in these young subjects, possibly representing a link between obesity and related co-morbidities.

Levels of macrophage migration inhibitory factor and glucocorticoids in chronic wound patients and their potential interactions with impaired wound endothelial progenitor cell migration

Macrophage migration inhibitory factor (MIF), a structurally and functionally unique pleiotropic mediator in inflammation and immune processes, was identified decades ago. There is now strong evidence that MIF promotes revascularization and is involved in wound healing processes. However, its exact role in wound healing is still a matter of debate. A cohort of 33 patients was recruited, including 14 patients with acute and 19 patients with chronic wounds. Both serum and wound fluid samples were collected from each patient, and MIF and cortisol concentrations were determined. To functionally underscore MIF's potential role in wound revascularization, a chemotaxis assay was adapted to test whether and to what extent serum samples and wound fluids of each group promote the chemotactic migration of endothelial progenitor cells (EPCs). MIF serum levels were significantly higher in chronic wound patients than in acute wound patients. Wound exudates of chronic wounds, however, contained a significantly lower concentration of MIF. In chronic wound patients, EPC migration might be delayed, as suggested by in vitro chemotaxis experiments. Despite the overall descriptive nature of this study, we conclude that MIF is correlated with occurrence of chronic wound. The increased MIF levels in the serum of chronic wound patients might be due to MIF's systemic effect of its proinflammatory activities, while its locally decreased levels in chronic wound exudates might be responsible for impaired recruitment of EPCs. Additional prospective data and detailed in vivo models are needed for a more comprehensive understanding of the role of MIF in chronic wound healing.

Platelet-derived growth factor-BB mediates cell migration through induction of activating transcription factor 4 and tenascin-C

The acute response to vascular cell injury, which underpins vasculo-occlusive pathologies such as atherogenesis and restenosis after percutaneous coronary intervention, involves a complex series of molecular events that alter patterns of gene expression and favor a synthetic phenotype. One transcription factor that has been implicated in this process is the evolutionarily conserved mammalian stress response pathway regulator activating transcription factor 4 (ATF-4). Here, we show for the first time that both mRNA and protein levels of ATF-4 are induced in smooth muscle cells (SMCs) by the potent migratory factor PDGF-BB through PDGFR-β. PDGF-BB also stimulates the expression of tenascin-C (TN-C), an extracellular matrix glycoprotein that regulates the activity of focal adhesion complexes, facilitating the SMC migration that underlies negative vascular remodeling in response to injury. Overexpression of ATF-4 increased transcript levels of the four TN-C isoforms in rat vascular SMCs, and ATF-4 knockdown inhibited PDGF-BB-inducible TN-C expression in vitro and injury-inducible TN-C protein expression in the balloon-injured rat artery wall. Furthermore, we show that ATF-4 is required for PDGF-BB-inducible SMC migration in response to injury. PDGF-BB-induced migration was also compromised in ATF-4 null mEFs, and this effect was rescued by the addition of TN-C. Our findings thus demonstrate the role of ATF-4 in both injury- and PDGF-BB-inducible TN-C expression and cell migration.

Macrophage migration inhibitory factor mediates hypoxia-induced pulmonary hypertension

Pulmonary hypertension (PH) is a devastating disease leading to progressive hypoxemia, right ventricular failure, and death. Hypoxia can play a pivotal role in PH etiology, inducing pulmonary vessel constriction and remodeling. These events lead to increased pulmonary vessel wall thickness, elevated vascular resistance and right ventricular hypertrophy. The current study examined the association of the inflammatory cytokine macrophage migration inhibitory factor (MIF) with chronic lung disease and its role in the development of hypoxia-induced PH. We found that plasma MIF in patients with primary PH or PH secondary to interstitial lung disease (ILD) was significantly higher than in the control group (P = 0.004 and 0.007, respectively). MIF involvement with hypoxia-induced fibroblast proliferation was examined in both a human cell-line and primary mouse cells from wild-type (mif⁺/⁺) and MIF-knockout (mif⁻/⁻) mice. In vitro, hypoxia-increased MIF mRNA, extracellular MIF protein accumulation and cell proliferation. Inhibition of MIF inflammatory activity reduced hypoxia-induced cell proliferation. However, hypoxia only increased proliferation of mif⁻/⁻ cells when they were supplemented with media from mif⁺/⁺ cells. This growth increase was suppressed by MIF inhibition. In vivo, chronic exposure of mice to a normobaric atmosphere of 10% oxygen increased lung tissue expression of mRNA encoding MIF and accumulation of MIF in plasma. Inhibition of the MIF inflammatory active site, during hypoxic exposure, significantly reduced pulmonary vascular remodeling, cardiac hypertrophy and right ventricular systolic pressure. The data suggest that MIF plays a critical role in hypoxia-induced PH, and its inhibition may be beneficial in preventing the development and progression of the disease.

Expression and function of macrophage migration inhibitory factor in the pathogenesis of UV-induced cutaneous nonmelanoma skin cancer

Chronic skin exposure to ultraviolet light stimulates the production of cytokines known to be involved in the initiation of skin cancer. Recent studies in mouse models suggested a role for macrophage migration inhibitory factor (MIF) in the UVB-induced pathogenesis of nonmelanoma skin cancer (NMSC). Our studies aimed at defining the pathophysiological function of MIF in cutaneous inflammatory reactions and in the development and progression of NMSC. Immunohistochemical analysis revealed a moderate expression of MIF in normal human skin samples but an enhanced expression of this cytokine in lesional skin of patients with actinic keratosis or cutaneous SCC. Enzyme-linked immunosorbent assay studies showed a time-dependent increase in MIF secretion after a moderate single-dose UVB irradiation in NHEKs and SCC tumor cells. MIF is known to interact with CXCR2, CXCR4 and CD74. These receptors are not constitutively expressed in keratinocytes and HaCaT cells and their expression is not induced by UVB irradiation either. However, stimulation with IFNγ upregulated CD74 surface expression in these cells. Affymetrix(®) Gene Chip analysis revealed that only keratinocytes prestimulated with IFNγ are responsive to MIF. These findings indicate that MIF may be an important factor in the pathogenesis of NMSC tumorigenesis and progression in an inflammatory environment.

Distinct immunoregulatory properties of macrophage migration inhibitory factors encoded by Eimeria parasites and their chicken host

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that plays an important role in host defense against a variety of microorganisms including protozoan parasites. Interestingly, some microbial pathogens also express a MIF-like protein, although its role in disease pathogenesis is not well understood. The aim of this study was to compare an Eimeria-encoded MIF (E.MIF) protein with chicken MIF (C.MIF) on the basis of their structural, immunological, and biological properties. E.MIF and C.MIF proteins, each with a glutathione S-transferase epitope tag, were expressed in Escherichia coli or COS-7 cells and purified by glutathione affinity chromatography. Rabbit antisera against the purified proteins demonstrated their mutual immunological cross-reactivity on Western blots, and immunolocalized intracellular native E.MIF to the Eimeria schizont, merozoite, and oocyst life cycle stages. HD11 chicken macrophages treated in vitro with C.MIF recombinant protein expressed increased levels of transcripts encoding interleukin-6 (IL-6), IL-17, and tumor necrosis factor superfamily member 15 (TNFSF15), but decreased levels of IL-8 transcripts, compared with cells treated with the PBS control; similar treatment with E.MIF only down-regulated IL-8 transcripts. Unlike recombinant E.MIF, C.MIF exhibited in vitro chemotactic activity for HD11 cells. Conversely, E.MIF, but not C.MIF, enhanced protection against experimental Eimeria infection, compared with the PBS control. These studies provide evidence for overlapping structural and antigenic properties, but distinct immunoregulatory roles, of E.MIF and C.MIF.

YK-4-279 inhibits ERG and ETV1 mediated prostate cancer cell invasion

Background

Genomic rearrangements involving the ETS family of transcription factors occur in 40–70% of prostate cancer cases. ERG and ETV1 are the most common ETS members observed in these genetic alterations. The high prevalence of these rearrangements and their biological significance represents a novel therapeutic target for the treatment of prostate cancer.

Methods and Findings

We recently reported the development of YK-4-279, a small molecule inhibitor of EWS-FLI1 oncoprotein in Ewing's Sarcoma. Since ERG and ETV1 belong to the same class of ETS factors as FLI1, we tested the ability of YK-4-279 to inhibit biological functions of ERG and ETV1 proteins in prostate cancer. YK-4-279 inhibited ERG and ETV1 mediated transcriptional activity in a luciferase assay. YK-4-279 also decreased ERG and ETV1 downstream target mRNA and protein expression in ETV1-fusion positive LNCaP and ERG fusion positive VCaP cells. YK-4-279 reduced the motility of LNCaP cells in a scratch assay and the invasive phenotype of both LNCaP and VCaP cells in a HUVEC invasion assay. Fusion-negative PC3 cells were unresponsive to YK-4-279. SiRNA mediated ERG knockdown in VCaP cells resulted in a loss of drug responsiveness. Concurrently, transient ERG expression in PC-3 cells resulted in increased invasive potential, which was reduced by YK-4-279.

Conclusion

These data demonstrate that YK-4-279 inhibits ERG and ETV1 biological activity in fusion-positive prostate cancer cells leading to decreased motility and invasion. Therefore, YK-4-279 may have an impact on metastasis in prostate cancer and it may be further evaluated for its clinical applications in prostate cancer in addition to Ewing's sarcoma.

MIF: a key player in cutaneous biology and wound healing

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.

A macrophage migration inhibitory factor like gene from scallop Chlamys farreri: Involvement in immune response and wound healing

Macrophage migration inhibitory factor (MIF) is an evolutionarily ancient and highly conserved cytokine with multiple functions. In the present study, a MIF-like gene was cloned from Zhikong scallop Chlamys farreri (designated as CfMIF) based on expressed sequence tag (EST) analysis and rapid amplification of cDNA ends (RACE) approach. The full-length cDNA of CfMIF was of 2296bp, consisting of a 5' untranslated region (UTR) of 60bp, a 3' UTR of 1903bp with a poly(A) tail and an open reading frame (ORF) of 333bp encoded 111 amino acid residues with a calculated molecular mass of 12.6kDa and a theoretical isoelectric point of 5.63. The deduced amino acid sequence of CfMIF shared 27-50.5% similarity with those of other known MIFs. A conserved MIF domain was identified in the deduced amino acid sequence of CfMIF, and conserved proline(2) and lysine(33) were also found to be present in CfMIF. Phylogenetic analysis revealed that CfMIF is one of MIF members. The tissue distribution and temporal expression of CfMIF in hemocytes of scallop after lipopolysaccharide (LPS), peptidoglycan (PGN) and β-glucan stimulation were detected by real-time RT-PCR. CfMIF gene was ubiquitously expressed in six selected tissues of healthy scallops, with the higher expression levels in hepatopancreas, mantle and gill. In comparison with the control group, the expression of CfMIF mRNA in hemocytes was up-regulated significantly at 6h, 24h and 48h after LPS treatment, and at all time points after PGN and glucan treatment. The cDNA fragment encoding mature peptide of CfMIF was recombined and expressed in Escherichia coli BL21 (DE3) pLysS. The recombinant protein of CfMIF (rCfMIF) promoted sheep fibroblast migration into scraped spaces in vitro. These results generated from the present study encourage us to suggest that CfMIF was a novel member of MIF family, and it was involved in immune response and wound healing by promoting fibroblast migration.

Macrophage migration inhibitory factor: a multifunctional cytokine in rheumatic diseases

Macrophage migration inhibitory factor (MIF) was originally identified in the culture medium of activated T lymphocytes as a soluble factor that inhibited the random migration of macrophages. MIF is now recognized to be a multipotent cytokine involved in the regulation of immune and inflammatory responses. Moreover, the pivotal nature of its involvement highlights the importance of MIF to the pathogenesis of various inflammatory disorders and suggests that blocking MIF may be a useful therapeutic strategy for treating these diseases. This paper discusses the function and expressional regulation of MIF in several rheumatic diseases and related conditions.

Enriched environment downregulates macrophage migration inhibitory factor and increases parvalbumin in the brain following experimental stroke

Housing rodents in an enriched environment (EE) following experimental stroke enhances neurological recovery. Understanding the underlying neural cues may provide the basis for improving stroke rehabilitation. We studied the contribution of brain macrophage migration inhibitory factor (MIF) to functional recovery after permanent middle cerebral artery occlusion (pMCAo) in rats. In the cerebral cortex, MIF is predominantly found in neurons, particularly in parvalbumin interneurons. Following pMCAo, MIF increases around the infarct core, where it is located to neurons and astrocytes. Housing rats in an EE after pMCAo resulted in a decrease of MIF protein levels in peri-infarct areas, which was accompanied by an increase in parvalbumin immunoreactive interneurons. Our data suggest that MIF is part of a signaling network involved in brain plasticity, and elevated neuronal and/or astrocytic MIF levels repress the recovery of sensory-motor function after stroke. Downregulating MIF could constitute a new therapeutic approach to promote recovery after stroke.

Dual role of macrophage migration inhibitory factor (MIF) in human breast cancer

Background

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine and mediator of acute and chronic inflammatory diseases. MIF is overexpressed in various tumours and has been suggested as a molecular link between chronic inflammation and cancer. MIF overexpression is observed in breast cancer but its causal role in the development of this tumour entity is unclear.

Methods

MIF levels in breast cancer cell lines were determined by ELISA and Western blot. CD74 was measured by Western blot, fluorescence microscopy and flow cytometry. Cell proliferation was studied by BrdU incorporation, cell adhesion by Matrigel adhesion assay, and cell invasion by migration assay through Matrigel-coated filters using the Transwell system. MIF expression in primary human breast cancers was measured by tissue microarray and a semi-quantitative immunoreactivity score (IRS) and comparison with histopathological parameters and patient outcome data.

Results

MIF was abundantly expressed in the non-invasive breast cancer cell lines MDA-MB-468 and ZR-75-1, but not in invasive MDA-MB-231 cells, which in turn expressed higher levels of the MIF-receptor CD74. Stimulation with exogenous MIF led to a dramatic upregulation of MIF secretion (50-fold) in MDA-MB-231 cells. Autocrine MIF promoted tumour cell proliferation, as indicated by blockade of MIF or CD74 in MDA-MB-231 and MDA-MB-468, and MDA-MB-231 invasiveness was enhanced by exogenous MIF. We correlated the expression of MIF with histopathological parameters and patient outcome data, using a tissue microarray of 175 primary invasive breast cancers and 35 normal control tissues. MIF was upregulated in breast cancer versus normal tissue (median IRS = 8 versus 6). MIF expression showed positive correlations with progesterone (p = 0.006) and estrogen (p = 0.028) receptor expression, markers of a favourable prognosis and a negative correlation to tumour size (p = 0.007). In line with these data, disease-specific overall (OS) as well as recurrence-free (RFS) survival was significantly improved in breast cancer patients with abundant cytosolic MIF expression compared to MIF low expressers (5-year OS = 67% versus 50%, p = 0.0019; 5-year RFS = 52% versus 36%, p = 0.0327).

Conclusion

We conclude that intracellular expression of MIF in breast cancer cells is beneficial, whereas extracellular MIF may play a pro-oncogenic role in promoting breast cancer cell-stroma interactions.

Surface expression of CD74 by type II alveolar epithelial cells: a potential mechanism for macrophage migration inhibitory factor-induced epithelial repair

Macrophage migration inhibitory factor (MIF) is a pleiotropic proinflammatory cytokine involved in acute lung injury and other processes such as wound repair and tumor growth. MIF exerts pro-proliferative effects on a variety of cell types including monocytes/macrophages, B cells, and gastric epithelial cell lines through binding to the major histocompatibility complex type II-associated invariant chain, CD74. In acute lung injury, inflammatory damage of the alveolar epithelium leads to loss of type I alveolar epithelial cells (AEC-I), which are replaced by proliferation and differentiation of type II alveolar epithelial cells (AEC-II). In this study we have investigated the potential of MIF to contribute to alveolar repair by stimulating alveolar epithelial cell proliferation. We show that murine AEC-II, but not AEC-I, express high surface levels of CD74 in vivo. Culture of AEC-II in vitro resulted in decreased mRNA levels for CD74 and loss of surface CD74 expression, which correlated with a transition of AEC-II to an AEC-I-like phenotype. MIF stimulation of AEC-II induced rapid and prolonged phosphorylation of ERK1/2 and Akt, increased expression of cyclins D1 and E, as well as AEC-II proliferation. Corresponding MIF signaling and enhanced thymidine incorporation was observed after MIF stimulation of MLE-12 cells transfected to overexpress CD74. In contrast, MIF did not induce MAPK activation, gene transcription, or increased proliferation in differentiated AEC-I-like cells that lack CD74. These data suggest a previously unidentified role of MIF-CD74 interaction by inducing proliferation of AEC-II, which may contribute to alveolar repair.

Amblyomma americanum (L): tick macrophage migration inhibitory factor peptide immunization lengthens lone star tick feeding intervals in vivo

Immunizations of New Zealand White rabbits with specific macrophage migration inhibitory factor (MIF) tick peptide (PEP) produced circulating anti-tick PEP antibodies in the hosts. Antibody titers of greater than 1:5000 to tick MIF peptide were observed for crude sera from PEP-immunized rabbits. PEP- and BSA-vaccinated rabbits were infested with Amblyomma americanum adults. Feeding intervals, female weights, egg masses and percent egg hatch were measured for ticks feeding on control and immunized hosts. Feeding intervals were significantly lengthened to 13.3 days for PEP-vaccinated hosts compared to BSA-vaccinated controls at 12.4 days, while female engorgement weights and egg masses were unchanged. By immunizing hosts using specific tick PEP, we were able to alter the length of time the ticks fed on their hosts.

Structural determinants of MIF functions in CXCR2-mediated inflammatory and atherogenic leukocyte recruitment

We have recently identified the archaic cytokine macrophage migration inhibitory factor (MIF) as a non-canonical ligand of the CXC chemokine receptors CXCR2 and CXCR4 in inflammatory and atherogenic cell recruitment. Because its affinity for CXCR2 was particularly high, we hypothesized that MIF may feature structural motives shared by canonical CXCR2 ligands, namely the conserved N-terminal Glu-Leu-Arg (ELR) motif. Sequence alignment and structural modeling indeed revealed a pseudo-(E)LR motif (Asp-44-X-Arg-11) constituted by non-adjacent residues in neighboring loops but with identical parallel spacing as in the authentic ELR motif. Structure-function analysis demonstrated that mutation of residues R11, D44, or both preserve proper folding and the intrinsic catalytic property of MIF but severely compromises its binding to CXCR2 and abrogates MIF/CXCR2-mediated functions in chemotaxis and arrest of monocytes on endothelium under flow conditions. R11A-MIF and the R11A/D44A-MIF double-mutant exhibited a pronounced defect in triggering leukocyte recruitment to early atherosclerotic endothelium in carotid arteries perfused ex vivo and upon application in a peritonitis model. The function of D44A-MIF in peritoneal leukocyte recruitment was preserved as a result of compensatory use of CXCR4. In conjunction, our data identify a pseudo-(E)LR motif as the structural determinant for MIF's activity as a non-canonical CXCR2 ligand, epitomizing the structural resemblance of chemokine-like ligands with chemokines and enabling selective targeting of pro-inflammatory MIF/CXCR2 interactions.

Macrophage migration inhibitory factor: a key cytokine in RA, SLE and atherosclerosis

Originally discovered and named as an in vitro inhibitor of macrophage migration, the cytokine macrophage migration inhibitory factor (MIF) has now been shown to be a key regulator of acute and chronic immuno-inflammatory conditions including rheumatoid arthritis (RA), atherosclerosis, and more recently systemic lupus erythematosus (SLE). Common inflammatory events in these diseases include activation of cells and infiltration by immune cells at the site of injury. MIF actively participates in multiple stages of the inflammatory response, acting on cells directly and/or potentiating the effects entrained by other stimuli. The overlap of inflammatory processes operating in these diseases, the known activities of MIF, and the observation of atherosclerosis as a major comorbidity of RA and SLE, make MIF a strong candidate for therapeutic targeting in these diseases. Moreover, the unique relationship between MIF and glucocorticoids, commonly used in the treatment of RA and SLE but associated with significant side effects, highlights the potential of MIF as a 'steroid sparing' therapeutic target encompassing all three conditions.