Macrophage migration inhibitory factor is required for NLRP3 inflammasome activation

Anemoside B4 Protects against Acute Lung Injury by Attenuating Inflammation through Blocking NLRP3 Inflammasome Activation and TLR4 Dimerization

Acute lung injury (ALI) is an acute inflammatory process in the lung parenchyma. Anemoside B4 (B4) was isolated from Pulsatilla, a plant-based drug against inflammation and commonly applied in traditional Chinese medicine. However, the anti-inflammatory effect and the mechanisms of B4 are not clear. In this study, we explored the potential mechanisms and anti-inflammatory activity of B4 both in vitro and in vivo. The results indicated that B4 suppressed the expression of iNOS, COX-2, NLRP3, caspase-1, and IL-1β. The ELISA assay results showed that B4 significantly restrained the release of inflammatory cytokines like TNF-α, IL-6, and IL-1β in macrophage cells. In addition, B4 rescued mitochondrial membrane potential (MMP) loss in (lipopolysaccharide) LPS plus ATP stimulated macrophage cells. Co-IP and molecular docking results illustrated that B4 disrupted the dimerization of TLR4. For in vivo results, B4 exhibited a protective effect on LPS and bleomycin- (BLM-) induced ALI in mice through suppressing the lesions of lung tissues, the release of inflammatory cytokines, and the levels of white blood cells, neutrophils, and lymphoid cells in the blood. Collectively, B4 has a protective effect on ALI via blocking TLR4 dimerization and NLRP3 inflammasome activation, suggesting that B4 is a potential agent for the treatment of ALI.

RACK1 Mediates NLRP3 Inflammasome Activation by Promoting NLRP3 Active Conformation and Inflammasome Assembly

The NLRP3 inflammasome, a critical component of the innate immune system, induces caspase-1 activation and interleukin (IL)-1β maturation in response to microbial infection and cellular damage. However, aberrant activation of the NLRP3 inflammasome contributes to the pathogenesis of several inflammatory disorders, including cryopyrin-associated periodic syndromes, Alzheimer's disease, type 2 diabetes, and atherosclerosis. Here, we identify the receptor for activated protein C kinase 1 (RACK1) as a component of the NLRP3 complexes in macrophages. RACK1 interacts with NLRP3 and NEK7 but not ASC. Suppression of RACK1 expression abrogates caspase-1 activation and IL-1β release in response to NLRP3- but not NLRC4- or AIM2-activating stimuli. This RACK1 function is independent of its ribosomal binding activity. Mechanistically, RACK1 promotes the active conformation of NLRP3 induced by activating stimuli and subsequent inflammasome assembly. These results demonstrate that RACK1 is a critical mediator for NLRP3 inflammasome activation.

Organic Selenium Reaches the Central Nervous System and Downmodulates Local Inflammation: A Complementary Therapy for Multiple Sclerosis?

Multiple sclerosis (MS) is an inflammatory and demyelinating disease of the central nervous system (CNS). The persistent inflammation is being mainly attributed to local oxidative stress and inflammasome activation implicated in the ensuing demyelination and axonal damage. Since new control measures remain necessary, we evaluated the preventive and therapeutic potential of a beta-selenium-lactic acid derivative (LAD-βSe), which is a source of organic selenium under development, to control experimental autoimmune encephalomyelitis (EAE) that is an animal model for MS. Two EAE murine models: C57BL/6 and SJL/J immunized with myelin oligodendrocyte glycoprotein and proteolipid protein, respectively, and a model of neurodegeneration induced by LPS in male C57BL/6 mice were used. The preventive potential of LAD-βSe was initially tested in C57BL/6 mice, the chronic MS model, by three different protocols that were started 14 days before or 1 or 7 days after EAE induction and were extended until the acute disease phase. These three procedures were denominated preventive therapy -14 days, 1 day, and 7 days, respectively. LAD-βSe administration significantly controlled clinical EAE development without triggering overt hepatic and renal dysfunction. In addition of a tolerogenic profile in dendritic cells from the mesenteric lymph nodes, LAD-βSe also downregulated cell amount, activation status of macrophages and microglia, NLRP3 (NOD-like receptors) inflammasome activation and other pro-inflammatory parameters in the CNS. The high Se levels found in the CNS suggested that the product crossed the blood-brain barrier having a possible local effect. The hypothesis that LAD-βSe was acting locally was then confirmed by using the LPS-induced neurodegeneration model that also displayed Se accumulation and downmodulation of pro-inflammatory parameters in the CNS. Remarkably, therapy with LAD-βSe soon after the first remitting episode in SJL/J mice, also significantly downmodulated local inflammation and clinical disease severity. This study indicates that LAD-βSe, and possibly other derivatives containing Se, are able to reach the CNS and have the potential to be used as preventive and therapeutic measures in distinct clinical forms of MS.

MIF associated with pulmonary hypertension susceptibility and severity in non-dialysis Chronic kidney disease patients

Pulmonary hypertension (PAH) is one of the more serious complications of Chronic kidney disease (CKD), and its exact pathogenesis has not been clarified. As an upstream proinflammatory factor, macrophage migration inhibitor (MIF) is involved in the occurrence and development of many diseases. This study aimed to detect the relationship between serum MIF and PAH in non-dialysis CKD patients. A total of 382 non-dialysis CKD patients were enrolled in this study. Bio-Plex cytokine assay was used to detect MIF. CKD patients were divided into the PAH group and non-PAH group according to echocardiographic results. Relative risk was determined by logistic regression analysis. The pulmonary artery pressure in the CKD group was higher than that in the control group ( p < 0.01). Pulmonary arterial pressure was higher in stage 4 to 5 CKD patients than in Stage 1 to 3 CKD patients ( p < 0. 01), and the incidence of PAH was also increased ( p < 0. 01). MIF in the CKD group were higher than in the control group ( p < 0.05). MIF in CKD patients with PAH were higher than those without PAH ( p < 0.05). Multivariate logistic regression analysis showed that MIF is correlated with PAH (OR = 10.745; 95% CI 2.288–89.447, p < 0.05). PAH is common in non-dialysis CKD patients, and with the deterioration of kidney disease, the incidence of PAH is gradually increased, indicating that MIF plays an important role in the development of PAH in CKD patients.

Necrotic cell death increases the release of macrophage migration inhibitory factor by monocytes/macrophages

Macrophage migration inhibitory factor (MIF) is a pleiotropic inflammatory molecule with both cytokine and noncytokine activity. MIF is constitutively released from multiple cell types via an unconventional secretory pathway that is not well defined. Here, we looked at MIF release from human and mouse monocytes/macrophages in response to different stimuli. While MIF release was not significantly altered in response to lipopolysaccharide or heat-killed Escherichia coli, cytotoxic stimuli strongly promoted release of MIF. MIF release was highly upregulated in cells undergoing necrosis, necroptosis and NLRP3 inflammasome-dependent pyroptosis. Our data suggest that cell death represents a major route for MIF release from myeloid cells. The functional significance of these findings and their potential importance in the context of autoimmune and inflammatory diseases warrant further investigation.

Macleaya cordata extracts exert antiviral effects in newborn mice with rotavirus-induced diarrhea via inhibiting the JAK2/STAT3 signaling pathway

Accumulating evidence demonstrates that Macleaya cordata extract exerts antiviral and anti-inflammatory effects in various diseases. The present study aimed to investigate the potential effects of M. cordata on rotavirus SA11-induced diarrhea in mice. Diarrhea severity, levels of inflammatory cytokines, histological changes in the small intestine and the underlying mechanisms were evaluated in rotavirus-stimulated mice treated with 1, 2 and 4 mg/kg/day M. cordata or 4 mg/kg/day ribavirin (positive control). M. cordata treatment effectively ameliorated rotavirus-induced diarrhea in a dose-dependent manner by decreasing viral RNA levels. In addition, M. cordata reduced the release of pro-inflammatory cytokines including migration inhibitory factor, interleukin (IL)-8, IL-β, interferon-γ and tumor necrosis factor-α, and elevated the secretion of the anti-inflammatory cytokine IL-10 following rotavirus infection. M. cordata inhibited intestinal epithelial cell apoptosis and improved intestinal inflammation after rotavirus infection. The study also revealed that M. cordata exerted antiviral and anti-inflammatory effects on rotavirus-induced diarrhea by suppressing the Janus kinase 2 (JAK2)/STAT3 pathway, as reflected by decreased protein expression of phosphorylated (p)-JAK2 and p-STAT3. Overall, M. cordata effectively inhibited the inflammation caused by rotavirus, which was closely associated with the suppression of JAK2/STAT3 phosphorylation. These data suggested that M. cordata may be applied as a treatment for rotavirus-induced diarrhea.

Role of the NLRP3 inflammasome in autoimmune diseases

NOD-like receptor family pyrin domain containing 3 (NLRP3) is an intracellular receptor that senses foreign pathogens and endogenous danger signals. It assembles with apoptosis-associated speck-like protein containing a CARD (ASC) and caspase-1 to form a multimeric protein called the NLRP3 inflammasome. Among its various functions, the NLRP3 inflammasome can induce the release of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 while also promoting gasdermin D (GSDMD)-mediated pyroptosis. Previous studies have established a vital role for the NLRP3 inflammasome in innate and adaptive immune system as well as its contribution to several autoimmune diseases including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), systemic sclerosis (SSc), and ankylosing spondylitis (AS). In this review, we briefly introduce the biological features of the NLRP3 inflammasome and present the mechanisms underlying its activation and regulation. We also summarize recent studies that have reported on the roles of NLRP3 inflammasome in the immune system and several autoimmune diseases, with a focus on therapeutic and clinical applications.

Novel cytokine marker available for skin irritation testing of medical devices using reconstructed human epidermis models

In biological safety evaluation of medical devices, false-negative results have been observed during skin irritation testing using the reconstructed human epidermis (RhE) model when measuring cell viability as a single marker. Therefore, to improve testing accuracy, this study conducted a comprehensive survey and performance evaluation of cytokines to identify a second marker. In addition to IL-1α, macrophage migration inhibitory factor (MIF) was newly identified as a candidate marker, in the Bio-Plex assay of EpiDerm model exposed to polymer sample extracts. Irritation based on cell viability level was not accurately determined in LabCyte model using silicone spiked with 25% heptanoic acid (HA). By contrast, the irritation potency was accurately assessed in detail by measuring IL-1α or MIF. Further, IL-1α and MIF levels in EpiDerm, LabCyte, and EpiSkin models stimulated with sodium dodecyl sulfate (SDS) were inversely correlated with cell viability, and were detected even at low SDS concentrations without cell toxicity. Additionally, MIF demonstrated greater S/N ratio and dose-dependency at high SDS concentrations in some models compared to IL-1α. These results indicated that MIF might be a useful second marker for improving the sensitivity and accuracy of skin irritation testing with RhE models.

Transcriptional and in silico analyses of MIF cytokine and TLR signalling interplay in the LPS inflammatory response of Ciona robusta

The close phylogenetic relationship between Ciona robusta and vertebrates makes it a powerful model for studying innate immunity and the evolution of immune genes. To elucidate the nature and dynamics of the immune response, the molecular mechanisms by which bacterial infection is detected and translated into inflammation and how potential pattern recognition receptors (PRRs) are involved in pathogen recognition in tunicate C. robusta (formerly known as Ciona intestinalis), we applied an approach combining bacterial infections, next-generation sequencing, qRT-PCR, bioinformatics and in silico analyses (criteria of a p-value < 0.05 and FDR < 0.05). A STRING analysis indicated a functional link between components of the Tlr/MyD88-dependent signalling pathway (Tlr2, MyD88, and Irak4) and components of the Nf-κB signalling pathway (Nf-κB, IκBα, and Ikkα) (p-value < 0.05, FDR < 0.05). A qRT-PCR analysis of immune genes selected from transcriptome data revealed Mif as more frequently expressed in the inflammatory response than inflammation mediator or effector molecules (e.g., Il-17s, Tnf-α, Tgf-β, Mmp9, Tlrs, MyD88, Irak4, Nf-κB, and galectins), suggesting close interplay between Mif cytokines and Nf-κB signalling pathway components in the biphasic activation of the inflammatory response. An in silico analyses of the 3′-UTR of Tlr2, MyD88, IκBα, Ikk, and Nf-κB transcripts showed the presence of GAIT elements, which are known to play key roles in the regulation of immune gene-specific translation in humans. These findings provide a new level of understanding of the mechanisms involved in the regulation of the C. robusta inflammatory response induced by LPS and suggest that in C. robusta, as in humans, a complex transcriptional and post-transcriptional control mechanism is involved in the regulation of several inflammatory genes.

Soluble mediators in packed red blood cells augment lipopolysaccharide-induced monocyte interleukin-1β production

BACKGROUND AND OBJECTIVES

Soluble mediators in packed red-blood-cell (PRBC) units have been hypothesized as a mechanism associated with transfusion-related immune modulation. Soluble mediators including damage-associated molecular patterns (DAMPs) are known to activate inflammasomes. Inflammasome complexes maturate caspase-1 and interleukin (IL)-1β. We assessed whether PRBC supernatants (SN) modulated IL-1β driven inflammation and whether macrophage migration inhibitory factor (MIF) was a contributing factor.

MATERIALS AND METHODS

Isolated monocytes were incubated with PRBC-SN in an in vitro transfusion model. Lipopolysaccharide (LPS) was added in parallel to model a bacterial infection. Separately, recombinant MIF was used in the model to assess its role in IL-1β driven inflammation. IL-1β and caspase-1 were quantified in the PRBC-SN and culture SN from the in vitro model.

RESULTS

PRBC-SN alone did not induce IL-1β production from monocytes. However, PRBC-SN alone increased caspase-1 production. LPS alone induced both IL-1β and caspase-1 production. PRBC-SN augmented LPS-driven IL-1β and caspase-1 production. Recombinant MIF did not modulate IL-1β production in our model.

CONCLUSIONS

Soluble mediators in PRBC modulate monocyte IL-1β inflammation, which may be a contributing factor to adverse effects of transfusion associated with poor patient outcomes. While MIF was present in PRBC-SN, we found no evidence that MIF was responsible for IL-1β associated immune modulation.

The role of annexin A1 in the modulation of the NLRP3 inflammasome

Annexins are well-known Ca²⁺ phospholipid-binding proteins, which have a wide variety of cellular functions. The role of annexin A1 (AnxA1) in the innate immune system has focused mainly on the anti-inflammatory and proresolving properties through its binding to the formyl-peptide receptor 2 (FPR2)/ALX receptor. However, studies suggesting an intracellular role of AnxA1 are emerging. In this study, we aimed to understand the role of AnxA1 for interleukin (IL)-1β release in response to activators of the nucleotide-binding domain leucine-rich repeat (NLR) and pyrin domain containing receptor 3 (NLRP3) inflammasome. Using AnxA1 knockout mice, we observed that AnxA1 is required for IL-1β release in vivo and in vitro. These effects were due to reduction of transcriptional levels of IL-1β, NLRP3 and caspase-1, a step called NLRP3 priming. Moreover, we demonstrate that AnxA1 co-localize and directly bind to NLRP3, suggesting the role of AnxA1 in inflammasome activation is independent of its anti-inflammatory role via FPR2. Therefore, AnxA1 regulates NLRP3 inflammasome priming and activation in a FPR2-independent manner.

Is Vimentin the Cause or Effect of Obstructive Sleep Apnea Development?

PURPOSE

In obstructive sleep apnea (OSA), hypoxia secondary to apnea and hypopnea and the resulting systemic inflammatory response are the main causes of comorbidities. The aim of this study was to investigate the relationship between OSA and vimentin, which plays an important role in the activation of cells that synthesize inflammatory cytokines.

MATERIALS AND METHODS

The study included 150 OSA patients (50 mild, 50 moderate, and 50 severe OSA) and 50 patients without OSA as a control group. Plasma vimentin levels were measured from peripheral blood samples using a commercial enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

The OSA patients in our study had significantly higher body mass index, apnea-hypopnea index (AHI), triglyceride level, mean oxygen desaturation, and plasma vimentin levels compared to the healthy control group (p = 0.007, 0.001, 0004, 0.001, and 0.001, respectively). Plasma vimentin level was significantly higher in the moderate and severe OSA groups compared to the control and mild OSA groups (p = 0.001 for all). There was no difference between severe and moderate OSA. There were significant correlations between plasma vimentin levels and OSA patients' AHI and mean oxygen desaturation (r = 0.46, p = 0.001; r = 0.214, p = 0.005).

CONCLUSION

In this study, we observed significant positive correlations between plasma vimentin level and OSA severity, weight, AHI, and mean oxygen desaturation. Vimentin may have utility as a biomarker in the follow-up and treatment of OSA.

Pathogenic contribution of the Macrophage migration inhibitory factor family to major depressive disorder and emerging tailored therapeutic approaches

BACKGROUND

Immunoinflammatory disorders are often accompanied by depression. Here, we review the available preclinical and clinical studies suggesting a role for the pro-inflammatory cytokine Macrophage migration inhibitory factor (MIF) and the second member of the MIF family, D-dopachrome tautomerase (D-DT; DDT), in the pathogenesis of Major Depressive Disorders (MDD).

METHODS

We prepared a narrative review from a search on PubMed of studies pertaining to MDD and MIF, as for October 2019. Both humans and animal studies haves been considered.

RESULTS

Preclinical data show conflicting results on the role of endogenous MIF and DDT in depression. In contrast, several human studies show that circulating MIF levels tend to increase during the course of MDD. Higher levels of inflammatory biomarkers have also been associated with poorer responses to antidepressants and the levels of MIF significantly decrease after treatment, despite this may not be necessarily associated to an improvement in psychiatric symptoms.

LIMITATIONS

This is a narrative and not a systematic review of the literature on the involvement of MIF in MDD. We have highlighted studies performed in humans and in animal models, irrespective of population size and methodological approach.

CONCLUSIONS

This review highlights a role of MIF, and possibly DDT, in the pathogenesis of MDD. Whilst studies in animal models are discordant, the studies in patients with MDD convergently suggest that MIF plays a role in induction and maintenance of the disease. Additional studies are also needed on DDT that often displays synergistic function with MIF and their receptors.

Deletion of macrophage migration inhibitory factor ameliorates inflammation in mice model severe acute pancreatitis

BACKGROUND

Macrophage migration inhibitory factor (MIF) is an important pro-inflammatory cytokine implicated in sepsis, rheumatoid arthritis and other diseases. However, the role of MIF in acute pancreatitis (AP) remains unclear. This study aims to explore the role of MIF in the pathogenesis of AP using MIF^-/- mice (referred to as KO) and the biological effects of pharmacological inhibition of MIF in l-arginine induced AP.

METHODS

AP was induced in C57BL/6 wild-type (referred to as WT) and KO mice by administration of l-arginine. The severity of AP was assessed by serum analysis of amylase and lipase, and of these pro-inflammatory cytokines TNF-α and IL-1β. Histological hematoxylin and eosin (H&E) and immunohistochemical staining of pancreatic tissues were examined for inflammation and expression of pro-inflammatory mediators. We also investigated the biological effects of pharmacological inhibition of MIF activity using ISO-1((S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester).

RESULTS

At 72 h after the induction of AP with l-arginine, significantly lower levels of serum amylase, lipase, TNF-α, and IL-1β were observed in KO mice when compared with WT controls. Histological examination further showed protective effects against pancreatic tissue damage and inflammation, with pancreatic expression of TNF-α, IL-1β and NF-κB p65 markedly reduced. Pharmacological inhibition of MIF activity with ISO-1 markedly mirrored the protective effect seen in the KO AP model providing further evidence that MIF is involved in the pathogenesis of AP.

CONCLUSION

Our data provided strong evidence for the participation of MIF in the pathogenesis of AP and subsequent inflammatory response. The genetic ablation of MIF or its inhibition with pharmacological agents significantly ameliorated the severity of AP.

Advances in Disease Mechanisms and Translational Technologies: Clinicopathologic Significance of Inflammasome Activation in Autoimmune Diseases

Autoimmune diseases are characterized by dysregulated immune tolerance to self and inflammatory damage to tissues and organs. The development of inflammation involves multiple innate and adaptive immune pathways. Inflammasomes are multimeric cytosolic protein complexes that form to mediate host immune responses upon recognizing pathogen- or damage-associated molecular patterns via pattern-recognition receptors (PRRs). The accelerating pace of inflammasome research has demonstrated important roles for inflammasome activation in many pathologic conditions, including infectious, metabolic, autoinflammatory, and autoimmune diseases. The inflammasome generally comprises a PRR, procaspase 1, and an adaptor molecule connecting the PRR and procaspase 1. Upon inflammasome activation, procaspase 1 becomes active caspase 1 that converts pro-interleukin-1β (proIL-1β) and proIL-18 into mature and active IL-1β and IL-18, respectively. The cytokines IL-1β and IL-18 have multipotent effects on immune and nonimmune cells and induce and promote systemic and local inflammatory responses. Human studies have shown increased levels of these cytokines, altered activation of inflammasome-related molecules, and/or the presence of inflammasome activators in rheumatic diseases, including systemic lupus erythematosus, rheumatoid arthritis, crystal-induced arthropathies, and Sjögren's syndrome. Such changes are found in the primary target organs, such as the kidneys, joints, and salivary glands, as well as in the cardiovascular system. In animal models of rheumatic diseases, inflammation and tissue damage improve upon genetic or pharmacologic targeting of the inflammasome, supporting its pathogenic role. Herein, we review the clinicopathologic significance and therapeutic targeting of inflammasome activation in rheumatic diseases and related conditions based on recent findings.

Parsing the IL-37-Mediated Suppression of Inflammasome Function

Interleukin (IL)-37 is a member of the IL-1 family of cytokines. Although its broad anti-inflammatory properties are well described, the effects of IL-37 on inflammasome function remain poorly understood. Performing gene expression analyses, ASC oligomerization/speck assays and caspase-1 assays in bone marrow-derived macrophages (BMDM), and employing an in vivo endotoxemia model, we studied how IL-37 affects the expression and maturation of IL-1β and IL-18, inflammasome activation, and pyroptosis in detail. IL-37 inhibited IL-1β production by NLRP3 and AIM2 inflammasomes, and IL-18 production by the NLRP3 inflammasome. This inhibition was partially attributable to effects on gene expression: whereas IL-37 did not affect lipopolysaccharide (LPS)-induced mRNA expression of Il18 or inflammasome components, IL-37-transgenic BMDM displayed an up to 83% inhibition of baseline and LPS-stimulated Il1b compared to their wild-type counterparts. Importantly, we observed that IL-37 suppresses nigericin- and silica-induced ASC oligomerization/speck formation (a step in inflammasome activation and subsequent caspase-1 activation), and pyroptosis (-50%). In mice subjected to endotoxemia, IL-37 inhibited plasma IL-1β (-78% compared to wild-type animals) and IL-18 (-61%). Thus, our study adds suppression of inflammasome activity to the portfolio of anti-inflammatory pathways employed by IL-37, highlighting this cytokine as a potential tool for treating inflammasome-driven diseases.

The Role of Macrophage Migration Inhibitory Factor in Alzheimer's Disease: Conventionally Pathogenetic or Unconventionally Protective?

Recent preclinical and clinical observations have offered relevant insights on the etiopathogenesis of late onset Alzheimer′s disease (AD) and upregulated immunoinflammatory events have been described as underlying mechanisms involved in the development of AD. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine produced by several cells of the innate and adaptive immune system, as well as non-immune cells. In the present review, we highlight experimental, genetic, and clinical studies on MIF in rodent models of AD and AD patients, and we discuss emerging therapeutic opportunities for tailored modulation of the activity of MIF, that may potentially be applied to AD patients. Dismantling the exact role of MIF and its receptors in AD may offer novel diagnostic and therapeutic opportunities in AD.

Assays for Inducing and Measuring Cell Death to Detect Macrophage Migration Inhibitory Factor (MIF) Release

Cell death is a vital process for maintaining tissue homeostasis and removing potentially harmful cells. Cell death can be both programmed and non-programmed and is commonly divided into two main forms, termed apoptotic and necrotic death modes. In this chapter cell death is classified into apoptosis, primary necrosis, pyroptosis, and necroptosis. This chapter outlines the measurement of these different types of cell death and the relationship of measuring MIF release in these assays.

Assessing the Role of MIF in Plasmodium spp. Infections Using Ex Vivo Models

Ex vivo techniques are a valuable tool for the investigation of how immune cells respond to Plasmodium spp. antigen, allowing examination of various aspects of the immune response under controlled conditions. Here we describe how to isolate peripheral blood mononuclear cells (PBMC) from donors and coculture them with purified P. falciparum-infected red blood cells (iRBC) to investigate the role of MIF during Plasmodium spp. infection.

Staining MIF in Cells for Confocal Microscopy

Confocal microscopy is a powerful technique for immunofluorescence imaging of cells and tissues. The technique allows for detailed analysis of intracellular localization of molecules, as well as three-dimensional representation and analysis of samples, and can be used as a gateway to more advanced techniques, including FLIM-FRET and super-resolution microscopy. Relatively few studies have used confocal microscopy to study intracellular localization of macrophage migration inhibitory factor (MIF) in detail. This chapter outlines basic protocols and tips for staining MIF in fixed cells for confocal analysis.

Flow Cytometry Phenotyping of Bone Marrow-Derived Macrophages from Wild-Type and Mif-/- Mice

Phenotyping cells by flow cytometry is a powerful way to identify cell type and any morphological changes during cell culture. The staining procedure used in this chapter enables the characterization of mouse macrophages by a flow cytometry antibody panel which can be used for both bone marrow-derived macrophages (BMM) and macrophages derived from other tissues, such as the mouse spleen or peritoneal cavity. The surface and intracellular staining methods are versatile and can be applied to flow cytometry staining of several different cell types by changing the surface markers used with knowledge of which receptors are expressed on different cell types.

Assays for Measuring the Role of MIF in NLRP3 Inflammasome Activation

Hallmarks of NLRP3 inflammasome activation include the cleavage and secretion of the mature forms of caspase-1, IL-1β, and IL-18 and aggregation of ASC into "specks." We have previously shown that macrophage migratory inhibitory factor (MIF) directly regulates activation of the NLRP3 inflammasome, inhibiting the release of interleukin (IL)-1α, IL-1β, and IL-18. Here we present protocols for studying activation of the NLRP3 inflammasome in human and mouse macrophages and peripheral blood mononuclear cells (PBMCs). These protocols can also be applied to different cell types, such as fibroblasts, neutrophils, endothelial cells, and epithelial cells, although further optimization may be required for each. We also cover the stimulation of macrophages with established NLRP3 inflammasome activators.

The small molecule macrophage migration inhibitory factor antagonist MIF098, inhibits pulmonary hypertension associated with murine SLE

Pulmonary arterial hypertension (PAH) is a severe complication of systemic lupus erythematosus (SLE), with unclear etiopathogenesis. We evaluated the role of macrophage migration inhibitory factor (MIF), which has been implicated in idiopathic pulmonary hypertension (PH), in SLE-associated PAH. Circulating MIF was measured in SLE patients, SLE-PAH patients, and healthy donors. In situ pulmonary artery MIF protein expression was determined in spontaneous SLE mice (MRL/lpr) and hypoxia-induced C57BL/6J mice. Daily MIF098 was administered to C57BL/6J mice, and these mice were maintained in a hypoxic chamber for 4 weeks. The right ventricular systolic pressure (RVSP) and pathological characteristics of the pulmonary artery (PA), such as hyperproliferation, muscularization, and fibrosis were then measured in each group of mice. Data were also obtained in vitro using pulmonary smooth muscle cells (PASMC) challenged with platelet-derived growth factor (PDGF)-BB or 1% O2 hypoxia. As a result, circulating MIF was elevated in SLE-PAH patients compared with SLE patients or healthy donors. Higher RVSP SLE mice produced more MIF protein than lower RVSP SLE mice in the pulmonary artery. MIF098 decreased RVSP and inhibited distal pulmonary artery hyperproliferation, muscularization, and collagen deposition in hypoxia challenged mice. In addition, MIF098 inhibited PASMC proliferation and migration by regulating mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 (MAPK/ERK1/2) signal- and cell-cycle-related proteins. MIF098 also reduced collagen synthesis by inhibiting the TGFβ1/Smad2/Smad3 pathway in cell-based experiments. In conclusion, MIF may serve as a biomarker and a therapeutic target of SLE-associated PAH. Pharmacologic MIF antagonism may be an effective means to ameliorate SLE-PAH.

A MIF-like effector suppresses plant immunity and facilitates nematode parasitism by interacting with plant annexins

Plant-parasitic nematodes secrete numerous effectors to facilitate parasitism, but detailed functions of nematode effectors and their plant targets remain largely unknown. Here, we characterized four macrophage migration inhibitory factors (MIFs) in Meloidogyne incognita resembling the MIFs secreted by human and animal parasites. Transcriptional data showed MiMIFs are up-regulated in parasitism. Immunolocalization provided evidence that MiMIF proteins are secreted from the nematode hypodermis to the parasite surface, detected in plant tissues and giant cells. In planta MiMIFs RNA interference in Arabidopsis decreased infection and nematode reproduction. Transient expression of MiMIF-2 could suppress Bax- and RBP1/Gpa2-induced cell death. MiMIF-2 ectopic expression led to higher levels of Arabidopsis susceptibility, suppressed immune responses triggered by flg22, and impaired [Ca2+]cyt influx induced by H2O2. The immunoprecipitation of MiMIF-2-interacting proteins, followed by co-immunoprecipitation and bimolecular fluorescence complementation validations, revealed specific interactions between MiMIF-2 and two Arabidopsis annexins, AnnAt1 and AnnAt4, involved in the transport of calcium ions, stress responses, and signal transduction. Suppression of expression or overexpression of these annexins modified nematode infection. Our results provide functional evidence that nematode effectors secreted from hypodermis to the parasite cuticle surface target host proteins and M. incognita uses MiMIFs to promote parasitism by interfering with the annexin-mediated plant immune responses.

Macrophage Migration Inhibitory Factor Triggers Inflammatory Responses During Very Virulent Infectious Bursal Disease Virus Infection

Infectious bursal disease (IBD) is one of the main threats to the poultry industry worldwide. In China, very virulent IBD virus (vvIBDV) is the main prevalent virus strain, causing inflammation, immunosuppression, and high mortality in young chickens. To determine whether this acute inflammation can trigger lesions or even death in chickens, it is important to study the mechanism of vvIBDV pathogenicity. Thus, in the current study, we investigated the inflammation response, bursal lesions, and mortality in chickens caused by vvIBDV at different time points postinfection. Results showed an upregulation of proinflammatory cytokines, including interleukin-1β and interleukin-18, and macrophage infiltration in bursa in response to vvIBDV infection. High-throughput proteomic sequencing based on isobaric tags for relative and absolute quantitation showed that chicken macrophage migration inhibitory factor (chMIF) was upregulated uniquely in primary bursal cells infected with vvIBDV compared with infection by nonpathogenic attenuated IBDV. We confirmed that chMIF was upregulated by vvIBDV infection both in vivo and in vitro. Moreover, chMIF was extracellularly secreted by infected DT40 and primary bursal cells. Further experiments revealed that the secreted chMIF could induce migration of peripheral blood mononuclear cells and promote transcription of proinflammatory cytokines in chicken primary macrophages. Notably, these effects of chMIF could be reduced by using an MIF specific inhibitor. Thus, our study elucidates critical molecular determinants underlying vvIBDV-mediated initiation of acute inflammation, which might be pivotal to understand the mechanism of vvIBDV pathogenicity.

BioStruct-Africa: empowering Africa-based scientists through structural biology knowledge transfer and mentoring - recent advances and future perspectives

Being able to visualize biology at the molecular level is essential for our understanding of the world. A structural biology approach reveals the molecular basis of disease processes and can guide the design of new drugs as well as aid in the optimization of existing medicines. However, due to the lack of a synchrotron light source, adequate infrastructure, skilled persons and incentives for scientists in addition to limited financial support, the majority of countries across the African continent do not conduct structural biology research. Nevertheless, with technological advances such as robotic protein crystallization and remote data collection capabilities offered by many synchrotron light sources, X-ray crystallography is now potentially accessible to Africa-based scientists. This leap in technology led to the establishment in 2017 of BioStruct-Africa, a non-profit organization (Swedish corporate ID: 802509-6689) whose core aim is capacity building for African students and researchers in the field of structural biology with a focus on prevalent diseases in the African continent. The team is mainly composed of, but not limited to, a group of structural biologists from the African diaspora. The members of BioStruct-Africa have taken up the mantle to serve as a catalyst in order to facilitate the information and technology transfer to those with the greatest desire and need within Africa. BioStruct-Africa achieves this by organizing workshops onsite at our partner universities and institutions based in Africa, followed by post-hoc online mentoring of participants to ensure sustainable capacity building. The workshops provide a theoretical background on protein crystallography, hands-on practical experience in protein crystallization, crystal harvesting and cryo-cooling, live remote data collection on a synchrotron beamline, but most importantly the links to drive further collaboration through research. Capacity building for Africa-based researchers in structural biology is crucial to win the fight against the neglected tropical diseases, e.g. ascariasis, hookworm, trichuriasis, lymphatic filariasis, active trachoma, loiasis, yellow fever, leprosy, rabies, sleeping sickness, onchocerciasis, schistosomiasis, etc., that constitute significant health, social and economic burdens to the continent. BioStruct-Africa aims to build local and national expertise that will have direct benefits for healthcare within the continent.

Macrophage migration inhibitory factor (MIF) as a therapeutic target for rheumatoid arthritis and systemic lupus erythematosus

Introduction. Macrophage migration inhibitory factor (MIF) is a pleiotropic inflammatory cytokine with upstream regulatory roles in innate and adaptive immunity and is implicated in the pathogenesis of autoimmune diseases including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Several classes of MIF inhibitors such as small molecule inhibitors and peptide inhibitors are in clinical development. Areas covered. The role of MIF in the pathogenesis of RA and SLE is examined; the authors review the structure, physiology and signaling characteristics of MIF and the related cytokine D-DT/MIF-2. The preclinical and clinical trial data for MIF inhibitors are also reviewed; information was retrieved from PubMed and ClinicalTrials.gov using the keywords MIF, D-DT/MIF-2, CD74, CD44, CXCR2, CXCR4, Jab-1, rheumatoid arthritis, systemic lupus erythematosus, MIF inhibitor, small molecule, anti-MIF, anti-CD74, and peptide inhibitor. Expert opinion. Studies in mice and in humans demonstrate the therapeutic potential of MIF inhibition for RA and SLE. MIF- directed approaches could be particularly efficacious in patients with high expression MIF genetic polymorphisms. In patients with RA and SLE and high expression MIF alleles, targeted MIF inhibition could be a precision medicine approach to treatment. Anti-MIF pharmacotherapies could also be steroid-sparing in patients with chronic glucocorticoid dependence or refractory autoimmune disease.

The NLRP3 Inflammasome: An Overview of Mechanisms of Activation and Regulation

The NLRP3 inflammasome is a critical component of the innate immune system that mediates caspase-1 activation and the secretion of proinflammatory cytokines IL-1β/IL-18 in response to microbial infection and cellular damage. However, the aberrant activation of the NLRP3 inflammasome has been linked with several inflammatory disorders, which include cryopyrin-associated periodic syndromes, Alzheimer's disease, diabetes, and atherosclerosis. The NLRP3 inflammasome is activated by diverse stimuli, and multiple molecular and cellular events, including ionic flux, mitochondrial dysfunction, and the production of reactive oxygen species, and lysosomal damage have been shown to trigger its activation. How NLRP3 responds to those signaling events and initiates the assembly of the NLRP3 inflammasome is not fully understood. In this review, we summarize our current understanding of the mechanisms of NLRP3 inflammasome activation by multiple signaling events, and its regulation by post-translational modifications and interacting partners of NLRP3.

MIF/CD74 axis participates in inflammatory activation of Schwann cells following sciatic nerve injury

Based on deep RNA sequencing of distal segments of lesioned sciatic nerves, a huge number of differentially expression genes (DEGs) were thus obtained and functionally analyzed. The inflammatory response was denoted as one of most significant biological processes following sciatic nerve injury. In the present study, ingenuity pathway analysis (IPA) demonstrated that macrophage migration inhibitory factor (MIF) was identified as a core regulator of inflammatory response through interaction with CD74 membrane receptor. By establishment of rat sciatic nerve transection model, we displayed that MIF was upregulated following sciatic nerve axotomy, in colocalization with Schwann cells (SCs). MIF promoted migration, proliferation, together with inflammatory responses of SCs in vitro. Immunoprecipitation showed that MIF interacted with CD74 receptor, through which to activate intracellular ERK and JNK signaling pathways. Interference of CD74 receptor using specific siRNA showed that the transcription of proinflammatory cytokines including TNF-α, IL-1β, as well as cytokine receptor TLR4 in SCs was significantly attenuated, supporting an participation of MIF/CD74 signal axis in SCs inflammatory response. The data provide a novel role of MIF in eliciting inflammatory response of peripheral nerve injury, which might be beneficial for precise therapy of peripheral nerve inflammation.

Circulating soluble levels of MIF in women with breast cancer in the molecular subtypes: relationship with Th17 cytokine profile

Breast cancer (BC) is a health problem worldwide; there is evidence that inflammatory cytokines are increased in BC. Macrophage migration inhibitory factor (MIF) has multiple effects on immune cells, inflammation and cancer. Besides, in previous studies, contradictory and uncertain results have been presented on the implication of Th17 cytokine profile in BC. The aim of this study was to evaluate the plasma levels of MIF and the Th17 cytokine profile in BC and their association with their molecular subtypes and clinical stage. A total of 150 women with BC of Ella Binational Breast Cancer Study and 60 healthy women (HW) were evaluated in cross-sectional study. The molecular subtypes were identified by immunohistochemistry. The plasma levels of MIF were quantified by ELISA and Th17 cytokine profile by multiplex system. MIF and IL-17 were significantly increased in BC versus HW (11.1 vs. 5.2 ng/mL and 14.8 pg/mL vs. 2.5 pg/mL p < 0.001, respectively). Our analysis showed that both MIF and IL-17A were associated with increased risk of breast cancer (OR 3.85 CI 95% 1.98-7.50 and OR 4.51 95% 1.83-11.15, respectively), higher in aggressive subtypes Luminal B, HER2 and TN. Likewise, we observed positive correlation between MIF and IL-17A (p < 0.001). In addition, IL-17E was lower in BC versus HW (p <0.001). Likewise, we observed a positive correlation between MIF and IL-17A (p < 0.001). In conclusion, both MIF and IL-17A were associated with high risk for breast cancer and aggressive molecular subtypes.

Expression of macrophage migration inhibitory factor in Aspergillus fumigatus keratitis

AIM

To investigate the expression of macrophage migration inhibitory factor (MIF) and detect its role in the innate immune response of fungal keratitis (FK).

METHODS

We collected the paraffin-embedded cornea tissues from 10 FK and 6 ocular trauma patients to explore the MIF expression by immunohistochemistry. Then we cultured telomease-immortalized human corneal epithelial cells (THCEs), stimulated by the hyphae suspension of Aspergillus fumigatus (A. fumigatus) to detect the change of MIF with or without the pretreatment of MIF inhibitor [4-Iodo-6-phenylpyrimidine (4-IPP)] by real-time polymerase chain reaction (PCR). The protein level of MIF was also tested by immunohistochemistry, and the level of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) mRNA were compared between normal, hyphae stimulated and 4-IPP pretreated groups by real-time PCR to study the influence of MIF on the expression of TNF-α and IL-6. Corneal severity of rats' FK models was documented by clinical scores, and real-time PCR. Western blot and immunohistochemistry were used to test the expression of MIF, TNF-α and IL-6 in rats' corneas.

RESULTS

In the corneas of FK patients, there was much stronger expression of MIF than that in the normal group showed by immunohistochemistry. In cultured THCEs stimulated by A. fumigatus, the expression of MIF became stronger in both immunohistochemistry and PCR at 16, 24, 32 and 48h post infection (p.i.; P<0.01, P<0.01, P<0.01, P<0.05). After pretreated with 4-IPP, the expression of MIF reduced at 4, 8, 16h p.i. (P<0.05, P<0.05, P<0.05) and the downstream TNF-α and IL-6 decreased obviously (P<0.05, P<0.01). In rats with A. fumigatus keratitis, the relative mRNA and protein level of MIF increased than those in the normal group by PCR (at 1d: P<0.01, 3d: P<0.01, 5d: P<0.01), Western blot and immunohistochemistry. After blocked MIF with 4-IPP, the clinical outcomes of rat keratitis showed markedly reduced inflammatory response (P<0.01), with TNF-α and IL-6 decreased in accordance with those in THCEs by PCR (P<0.05, P<0.01).

CONCLUSION

The expression of MIF increased significantly in FK patients, THCEs and rats stimulated by A. fumigatus. After blocked with 4-IPP, the expression of MIF reduced, and so did its downstream cytokines: TNF-α and IL-6. The inflammation reaction of the rats' corneas lightened after pretreated with 4-IPP. MIF may play a role in the innate immune response of the corneal resistance against A. fumigatus.

Macrophage migration inhibitory factor is involved in inflammation response in pathogen challenged Apostichopus japonicus

Macrophage migration inhibitory factor (MIF) is a cytokine and plays critical roles in inflammatory and immune responses in vertebrates. However, its functional role in inflammation has not been well studied in invertebrates. In the present study, we cloned and characterized MIF gene from Apostichopus japonicus by RNA-seq and RACE approaches (designated as AjMIF). A 1047 bp fragment representing the full-length cDNA of AjMIF was obtained, including a 5' UTR of 100 bp, an open reading frame (ORF) of 366 bp encoding a polypeptide of 121 amino acids residues with the molecular weight of 13.43 kDa and theoretical isoelectric point of 5.63 and a 3' UTR of 580 bp. SMART analysis showed that AjMIF has conserved MIF domain (2-117aa) similar to its mammalian counterparts. The amino terminal proline residue (P²) and invariant lysine residue (K³³) which are critical active sites of tautomerase activity in mammalian MIF were also detected. Phylogenic analysis and multiple alignments have shown that AjMIF shared higher degree of structural conservation and sequence identities with other counterparts from invertebrates and vertebrates. For Vibrio splendidus challenged sea cucumber, the peak expression of AjMIF mRNAs in coelomocytes were detected at 6 h (23.5-fold) and remained at high levels until 24 h (4.01-fold), and returned to normal level at 48 h in comparison with that of the control group. Similarly, a significant increase in the relative mRNA levels of AjMIF was also found in 10 μg mL^-1 LPS-exposed primary cultured coelomocytes. Functional analysis indicated that recombinant AjMIF incubation could promote inflammatory response related genes of Ajp105, AjVEGF, AjMMP1 and AjHMGB3 expression by 1.35-fold, 1.36-fold, 1.83-fold and 1.27-fold increase, respectively, which was consistent with the findings in vertebrate MIFs. All these results collectively suggested that AjMIF had a similar function to MIFs in higher animals and might serve as a candidate cytokine in inflammatory regulation in sea cucumber.

NLRP3 Inflammasome and Inflammatory Bowel Disease

NLRP3 inflammasome can be widely found in epithelial cells and immune cells. The NOD-like receptors (NLRs) family member NLRP3 contains a central nucleotide-binding and oligomerization (NACHT) domain which facilitates self-oligomerization and has ATPase activity. The C-terminal conserves a leucine-rich repeats (LRRs) domain which can modulate NLRP3 activity and sense endogenous alarmins and microbial ligands. In contrast, the N-terminal pyrin domain (PYD) can account for homotypic interactions with the adaptor protein-ASC of NLRP3 inflammasome. These characters enable it function in innate immunity. Its downstream effector proteins include caspase-1 and IL-1β etc. which exhibit protective or detrimental roles in mucosal immunity in different studies. Here, we comprehensively review the current literature regarding the physiology of NLRP3 inflammasome and its potential roles in the pathogenesis of IBD. We also discuss about the complex interactions among the NLRP3 inflammasome, mucosal immune response, and gut homeostasis as found in experimental models and IBD patients.

Secretory vimentin is associated with coronary artery disease in patients and induces atherogenesis in ApoE-/- mice

PURPOSE

The present study aimed to investigate the relationship between serum levels of secretory vimentin and coronary artery disease (CAD). The biological effect of secretory vimentin was ascertained by experiments.

METHODS

We analysed serum levels of secretory vimentin in CAD patients (n = 288) and non-CAD controls (n = 195) by ELISA. To evaluate the pro-inflammatory effects of secreted vimentin, the human aortic endothelial cells (HAECs) and human peripheral blood mononuclear cells (PBMCs) were treated with recombinant vimentin or saline. Intraperitoneal injection of vimentin (1 μg/each) or saline was performed every other day for 12 weeks in ApoE^-/- mice for assessment of atherogenic effect.

RESULTS

Serum levels of secretory vimentin were significantly increased in CAD patients than in health controls (p < 0.05), and correlated with the number of diseased coronary arteries, Syntax and Gensini score (for all comparison, p < 0.01). Logistic regression analysis showed that vimentin level is an independent determinant of CAD. In experiments, recombinant vimentin protein enhanced the expression of adhesion molecules and inflammatory cytokines in both endothelial cells and macrophages. This protein also promoted macrophage-endothelial cells adhesion in vitro and the recruitment of leukocytes to mesenteric venules in C57BL/6 mice. Compared with saline, intraperitoneal injection of recombinant vimentin (1 μg/each) every other day induced atherogenesis in ApoE^-/- mice at 12-weeks, with significant increase of inflammatory cytokine and adhesion molecules expression in aortic tissue (p < 0.05).

CONCLUSION

Serum vimentin levels are associated with the presence and the severity of CAD. Vimentin protein promotes atherogenesis in ApoE^-/- mice.

Optimization of Laboratory Ordering Practices for Complete Blood Count With Differential

Objectives

To investigate the utilization of CBC and CBC with differential (CBC w/diff) tests at University of Alabama at Birmingham Hospital, and to determine if a reduction in CBC w/diff tests could be achieved without negatively impacting patient care.

Methods

The quantity of testing and distribution of repeated tests before, during, and after an educational intervention were compared.

Results

CBC w/diff tests were ordered 10-fold more frequently than CBC tests. The trauma burn intensive care unit ordered the most CBC w/diff tests, with repeat tests done every 4 or 12 hours. The educational intervention reduced the number of CBC w/diff tests ordered and tests repeated every 12 hours.

Conclusions

The educational intervention changed the ordering practices of CBC w/diff and CBC tests. This was sustained after the intervention and no negative effects on patient care were noted. Similar interventions may lead to optimization of ordering practices of other laboratory tests.

Tissue Destruction Caused by Entamoeba histolytica Parasite: Cell Death, Inflammation, Invasion, and the Gut Microbiome

Purpose of Review

Entamoeba histolytica is a protozoan parasite that causes amebiasis, which remains a significant cause of morbidity and mortality worldwide. E. histolytica causes tissue destruction which leads to clinical disease. This review outlines some of the recent advances that have furthered our understanding of the processes that lead to the tissue damage caused by E. histolytica.

Recent Findings

Recent studies have identified new mechanisms involved in E. histolytica–induced tissue damage. These include (i) new form of contact-dependent killing called trogocytosis; (ii) parasite-produced cytokine, macrophage migration inhibitory factor, that contributes to inflammation; (iii) exploitation of host immune response to promote invasion; and (iv) the contribution of the gut microbiome to clinical disease.

Summary

Targeting these mechanisms that result in tissue injury should be a focus of future research for the development of improved preventive and therapeutic strategies for amebiasis.

Cells under stress: The mechanical environment shapes inflammasome responses to danger signals

Many intracellular signals, such as host danger-associated molecules and bacterial toxins during infection, elicit inflammasome activation. However, the mechanical environment in tissues may also influence the sensitivity of various inflammasomes to activation. The cellular mechanical environment is determined by the extracellular tissue stiffness, or its inverse, tissue compliance. Tissue stiffness is sensed by the intracellular cytoskeleton through a process termed mechanotransduction. Thus, extracellular compliance and the intracellular cytoskeleton may regulate the sensitivity of inflammasome activation. Control of proinflammatory signaling by tissue compliance may contribute to the pathogenesis of diseases such as ventilator-induced lung injury during bacterial pneumonia and tissue fibrosis in inflammatory disorders. The responsible signaling cascades in inflammasome activation pathways and mechanotransduction crosstalk are not yet fully understood. This rather different immunomodulatory perspective will be reviewed and open questions discussed here.

Inhibition of macrophage migration inhibitory factor attenuates inflammation and fetal kidney injury in a rat model of acute pancreatitis in pregnancy

Acute pancreatitis in pregnancy (APIP) is a severe disease during pregnancy that mostly occurs during the third trimester. It can lead to additional complications including preterm delivery and high fetal mortality. In this study, we investigated the protective effects of (S, R)-3-(4-hydroxyphenyl)-4, 5dihydro-5-isoxazole acetic methyl ester (ISO-1), an inhibitor of macrophage migration inhibitory factor (MIF), on fetal kidney injury associated with the maternal acute necrotizing pancreatitis (ANP) and its potential mechanisms in a rat model. The APIP rat model was induced by retrograde infusion of sodium taurocholate saline solution into biliopancreatic duct. ISO-1 was given by intraperitoneally injection 30 min before the model was induced. The levels of maternal serum amylase, lipase, tumor necrosis factor-α (TNF-α) and interleukins (IL)-1β were measured. Maternal pancreas and fetal kidney injury were evaluated, and the expressions of MIF, phospho-p38MAPK (p-p38), nuclear factor-κB (NF-κB), TNF-α, IL-1β in fetal kidneys were detected. The results showed that fetal rats exhibited obvious acute kidney injury during APIP, and pregnant rats pretreated with ISO-1 notably attenuated the lesions. ISO-1 also significantly reduced the expression of MIF and the activations of p38MAPK, NF-κB, as well as the levels of TNF-α and IL-1β. These results indicated that ISO-1 could attenuate fetal kidney injury in pregnant rats with ANP by inhibiting MIF mediated p38MAPK/NF-κB signal pathways to reduce inflammatory response.

Modulating T Cell Responses via Autophagy: The Intrinsic Influence Controlling the Function of Both Antigen-Presenting Cells and T Cells

Autophagy is a homeostatic and inducible process affecting multiple aspects of the immune system. This intrinsic cellular process is involved in MHC-antigen (Ag) presentation, inflammatory signaling, cytokine regulation, and cellular metabolism. In the context of T cell responses, autophagy has an influential hand in dictating responses to self and non-self by controlling extrinsic factors (e.g., MHC-Ag, cytokine production) in antigen-presenting cells (APC) and intrinsic factors (e.g., cell signaling, survival, cytokine production, and metabolism) in T cells. These attributes make autophagy an attractive therapeutic target to modulate T cell responses. In this review, we examine the impact autophagy has on T cell responses by modulating multiple aspects of APC function; the importance of autophagy in the activation, differentiation and homeostasis of T cells; and discuss how the modulation of autophagy could influence T cell responses.

Macrophage Migration Inhibitory Factor (MIF) Drives Murine Psoriasiform Dermatitis

The immunomodulator Macrophage Migration Inhibitory Factor (MIF) exerts pleiotropic immunomodulatory activities and has been implicated in the pathogenesis of diverse inflammatory diseases. Expression levels of MIF are also significantly elevated in the skin and serum of psoriasis patients, but the pathogenic significance of MIF in psoriasis is unknown. We have therefore addressed the role of MIF in two mouse models of psoriasis, namely in the imiquimod-induced psoriasiform dermatitis (IIPD) and the IL-23-induced dermatitis model. Daily treatment with Aldara™ cream, containing imiquimod, markedly increased the abundance of MIF in the skin and generated a cellular skin expression pattern of MIF closely resembling that in human plaque psoriasis. Deficiency in MIF significantly alleviated IIPD. On the clinical level, all hallmarks of psoriasiform dermatitis, including erythema, skin infiltration, and desquamation were reduced in Mif^−/− mice. On the histopathological level, MIF deficiency decreased keratinocyte hyperproliferation, inflammatory cell infiltration, specifically with respect to monocyte-derived cells, and dermal angiogenesis, suggesting that MIF may be involved in the pathogenesis of psoriasiform dermatitis through several mechanisms. Similarly, MIF deficiency also significantly reduced disease in the IL-23-induced dermatitis model, suggesting that MIF is involved in the pathogenic pathways activated by IL-23 and required to achieve full-blown psoriasiform dermatitis. Collectively, our results lend support to a possible disease-promoting role of MIF in psoriasis, which should be further investigated.

Neutralization of macrophage migration inhibitory factor improves host survival after Clostridium difficile infection

Clostridium difficile is an important cause of nosocomial diarrhea in the western world. Toxins (A, B, and binary toxins) generated by C. difficile bacteria damage intestinal epithelial cells. Hallmarks of host response to C. difficile infection (CDI) include upregulation of inflammatory mediators and tissue infiltration by immune cells. Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine that is known to enhance the host immune response to infectious pathogens. Additionally, MIF can adversely impact host survival to numerous infections. The role of MIF in the pathogenesis of CDI remains poorly understood. Here, we show that patients with CDI had significantly higher circulating MIF compared to patients who had diarrhea but tested negative for C. difficile (non-CDI controls). Similarly, in a mouse model, C. difficile challenge significantly increased levels of plasma and tissue MIF. Antibody-mediated depletion of MIF decreased C. difficile-induced inflammatory responses, clinical disease, and mortality. Together, these results uncover a potential role for MIF in exacerbating CDI and suggest that use of anti-MIF antibodies may represent a therapeutic strategy to curb host inflammatory responses and improve disease outcomes in CDI.

Blocking Macrophage Migration Inhibitory Factor Protects Against Cisplatin-Induced Acute Kidney Injury in Mice

Macrophage migration inhibitory factor (MIF) is elevated in patients with acute kidney injury (AKI) and is suggested as a potential predictor for renal replacement therapy in AKI. In this study, we found that MIF also plays a pathogenic role and is a therapeutic target for AKI. In a cisplatin-induced AKI mouse model, elevated plasma MIF correlated with increased serum creatinine and the severity of renal inflammation and tubular necrosis, whereas deletion of MIF protected the kidney from cisplatin-induced AKI by largely improving renal functional and histological injury, and suppressing renal inflammation including upregulation of cytokines such as interleukin (IL)-1β, tumor necrosis factor-alpha (TNF-α), IL-6, inducible nitric oxide synthase (iNOS), MCP-1, IL-8, and infiltration of macrophages, neutrophils, and T cells. We next developed a novel therapeutic strategy for AKI by blocking the endogenous MIF with an MIF inhibitor, ribosomal protein S19 (RPS19). Similar to the MIF-knockout mice, treatment with RPS19, but not the mutant RPS19, suppressed cisplatin-induced AKI. Mechanistically, we found that both genetic knockout and pharmacological inhibition of MIF protected against AKI by inactivating the CD74-nuclear factor κB (NF-κB) signaling. In conclusion, MIF is pathogenic in cisplatin-induced AKI. Targeting MIF with an MIF inhibitor RPS19 could be a promising therapeutic potential for AKI.