Rediscovering MIF: New Tricks for an Old Cytokine

MIF-Modulated Spinal Proteins Associated with Persistent Bladder Pain: A Proteomics Study

Bladder pain is a prominent symptom in Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS). We studied spinal mechanisms of bladder pain in mice using a model where repeated activation of intravesical Protease Activated Receptor-4 (PAR4) results in persistent bladder hyperalgesia (BHA) with little or no bladder inflammation. Persistent BHA is mediated by spinal macrophage migration inhibitory factor (MIF), and is associated with changes in lumbosacral proteomics. We investigated the contribution of individual spinal MIF receptors to persistent bladder pain as well as the spinal proteomics changes associated with relief of persistent BHA by spinal MIF antagonism. Female mice with persistent BHA received either intrathecal (i.t.) MIF monoclonal antibodies (mAb) or mouse IgG1 (isotype control antibody). MIF antagonism temporarily reversed persistent BHA (peak effect: 2 h), while control IgG1 had no effect. Moreover, i.t. antagonism of the MIF receptors CD74 and C-X-C chemokine receptor type 4 (CXCR4) partially reversed persistent BHA. For proteomics experiments, four separate groups of mice received either repeated intravesical scrambled peptide and sham i.t. injection (control, no pain group) or repeated intravesical PAR4 and: sham i.t.; isotype IgG1 i.t. (15 μg); or MIF mAb (15 μg). L6-S1 spinal segments were excised 2 h post-injection and examined for proteomics changes using LC-MS/MS. Unbiased proteomics analysis identified and relatively quantified 6739 proteins. We selected proteins that showed significant changes compared to control (no pain group) after intravesical PAR4 (sham or IgG i.t. treatment) and showed no significant change after i.t. MIF antagonism. Six proteins decreased during persistent BHA (V-set transmembrane domain-containing protein 2-like confirmed by immunohistochemistry), while two proteins increased. Spinal MIF antagonism reversed protein changes. Therefore, spinal MIF and MIF receptors mediate persistent BHA and changes in specific spinal proteins. These novel MIF-modulated spinal proteins represent possible new targets to disrupt spinal mechanisms that mediate persistent bladder pain.

Inflammasome-Related Genetic Polymorphisms as Severity Biomarkers of COVID-19

The most critical forms of coronavirus disease 2019 (COVID-19) are associated with excessive activation of the inflammasome. Despite the COVID-19 impact on public health, we still do not fully understand the mechanisms by which the inflammatory response influences disease prognosis. Accordingly, we aimed to elucidate the role of polymorphisms in the key genes of the formation and signaling of the inflammasome as biomarkers of COVID-19 severity. For this purpose, a large and well-defined cohort of 377 COVID-19 patients with mild (n = 72), moderate (n = 84), severe (n = 100), and critical (n = 121) infections were included. A total of 24 polymorphisms located in inflammasome-related genes (NLRP3, NLRC4, NLRP1, CARD8, CASP1, IL1B, IL18, NFKB1, ATG16L1, and MIF) were genotyped in all of the patients and in the 192 healthy controls (HCs) (who were without COVID-19 at the time of and before the study) by RT-qPCR. Our results showed that patients with mild, moderate, severe, and critical COVID-19 presented similar allelic and genotypic distribution in all the variants studied. No statistically significant differences in the haplotypic distribution of NLRP3, NLRC4, NLRP1, CARD8, CASP1, IL1B, and ATG16L1 were observed between COVID-19 patients, who were stratified by disease severity. Each stratified group of patients presented a similar genetic distribution to the HCs. In conclusion, our results suggest that the inflammasome polymorphisms studied are not associated with the worsening of COVID-19.

High temperature requirement A1 and macrophage migration inhibitory factor in the cerebrospinal fluid; a potential marker of conversion from relapsing-remitting to secondary progressive multiple sclerosis

BACKGROUND

Predictive and prognostic biomarkers for multiple sclerosis (MS) remain a significant gap in MS diagnosis and treatment monitoring. Currently, there are no timely markers to diagnose the transition to secondary progressive MS (SPMS).

OBJECTIVE

This study aims to evaluate the discriminatory potential of the High temperature requirement serine protease (HTRA1)/Macrophage migration inhibitory factor (MIF) cerebrospinal fluid (CSF) ratio in distinguishing relapsing-remitting (RRMS) patients from SPMS patients.

METHODS

The MIF and HTRA1 CSF levels were determined using ELISA in healthy controls (n = 23), RRMS patients before (n = 22) and after 1 year of dimethyl fumarate treatment (n = 11), as well as in SPMS patients before (n = 11) and after 2 years of mitoxantrone treatment (n = 7). The ability of the HTRA1/MIF ratio to discriminate the different groups was determined using receiver operating curve (ROC) analyses.

RESULTS

The ratio was significantly increased in treatment naïve RRMS patients while decreased again in SPMS patients at baseline. Systemic administrated disease modifying treatment (DMT) only significantly affected the ratio in RRMS patients. ROC analysis demonstrated that the ratio could discriminate treatment naïve RRMS patients from SPMS patients with 91% sensitivity and 100% specificity.

CONCLUSION

The HTRA1/MIF ratio is a strong candidate as a MS biomarker for SPMS conversion.

MIF modulates p38/ERK phosphorylation via MKP-1 induction in sarcoidosis

Macrophage migration inhibitory factor (MIF) is a versatile cytokine that influences a variety of cellular processes important for immune regulation and tissue homeostasis. Sarcoidosis is a granulomatous disease characterized by extensive local inflammation and increased T helper cell mediated cytokines. We have shown that MIF has a modulatory role in cytokine networks in sarcoidosis. We investigated the effect of exogenous MIF on sarcoidosis alveolar macrophages (AMs), CD14+ monocytes and peripheral blood mononuclear cells (PBMCs). Our results showed that MIF negatively regulates the increased MAPKs (pp38 and pERK1/2) activation by inducing Mitogen-activated protein kinase phosphatase (MKP)-1. We found that MIF decreased IL-6 and IL-1β production, increased the percentage of regulatory T-cells (Tregs), and induced IL-1R antagonist (IL-1RA) and IL-10 production. Thus, the results of our study suggest that exogenous MIF modulates MAPK activation by inducing MKP-1and Tregs as well as IL-10 and IL-1RA, and hence plays a modulatory role in immune activation in sarcoidosis.

Association of MIF-173G/C, IL-4 VNTR, and IL-1RA VNTR variants with FMF-related amyloidosis in a Turkish cohort

The most important complication of familial Mediterranean fever (FMF) is secondary amyloidosis. The aim of this study is to investigate the risk of developing FMF-related amyloidosis with macrophage migration inhibitory factor (MIF), interleukin 4 (IL-4), and IL-1 receptor antagonist (IL-1RA) variants. This study included 62 FMF patients with amyloidosis, 110 FMF patients without amyloidosis, and 120 controls. The clinical information of the patient groups was compared. MIF-173G/C, IL-4 variant number tandem repeat (VNTR), and IL-1RA VNTR variants were analyzed for all participants. The use of colchicine, pleurisy, and appendectomy was more common in FMF patients with amyloidosis than in FMF patients without amyloidosis. MIF-173G/C C/C genotype and C allele were higher in both patient groups compared to controls. IL-1RA VNTR A1/A2 and A1/A4 genotypes and A1-A4 alleles were more common in both patient groups than controls. The IL-4 VNTR P1 allele was more common in FMF patients with amyloidosis compared to controls. The MIF-173G/C allele and the IL-1RA VNTR A1-A4 allele are associated with FMF in the Turkish population but not with amyloidosis risk in FMF patients. The IL-4 VNTR P1 allele is more common in FMF patients with amyloidosis than in healthy individuals.

Identification of genes associated with gall bladder cell carcinogenesis: Implications in targeted therapy of gall bladder cancer

Gall bladder cancer (GBC) is becoming a very devastating form of hepatobiliary cancer in India. Every year new cases of GBC are quite high in India. Despite recent advanced multimodality treatment options, the survival of GBC patients is very low. If the disease is diagnosed at the advanced stage (with local nodal metastasis or distant metastasis) or surgical resection is inoperable, the prognosis of those patients is very poor. So, perspectives of targeted therapy are being taken. Targeted therapy includes hormone therapy, proteasome inhibitors, signal transduction and apoptosis inhibitors, angiogenesis inhibitors, and immunotherapeutic agents. One such signal transduction inhibitor is the specific short interfering RNA (siRNA) or short hairpin RNA (shRNA). For developing siRNA-mediated therapy shRNA, although several preclinical studies to evaluate the efficacy of these key molecules have been performed using gall bladder cells, many more clinical trials are required. To date, many such genes have been identified. This review will discuss the recently identified genes associated with GBC and those that have implications in its treatment by siRNA or shRNA.

Inflammation plays a critical role in damage to the bronchiolar epithelium induced by Trueperella pyogenes in vitro and in vivo

Trueperella pyogenes can cause severe pulmonary disease in swine, but the mechanism of pathogenesis is not well defined. T. pyogenes-induced damage to porcine bronchial epithelial cells (PBECs), porcine precision-cut lung slices (PCLS), and respiratory epithelium of mice remains unknown. In this study, we used T. pyogenes 20121 to infect PBECs in air-liquid interface conditions and porcine PCLS. T. pyogenes could adhere to, colonize, and induce cytotoxic effect on PBECs and the luminal surface of bronchi in PCLS, which damaged the bronchiolar epithelium. Moreover, bronchiolar epithelial cells showed extensive degeneration in the lungs of infected mice. Furthermore, western blot showed that the NOD-like receptor (NLR)/C-terminal caspase recruitment domain (ASC)/caspase-1 axis and nuclear factor-kappa B pathway were involved in inflammation in PCLS and lungs of mice, which also confirms that porcine PCLS provide a platform to analyze the pulmonary immune response. Meanwhile, the levels of p-c-Jun N-terminal kinase, p-extracellular signal-regulated kinase, and p-protein kinase B (AKT) were increased significantly, which indicated the mitogen-activated protein kinase and Akt pathways were also involved in inflammation in T. pyogenes-infected mice. In addition, we used T. pyogenes 20121 to infect tumor necrosis factor-alpha (tnf-α-/-) mice, and the results indicated that apoptosis and injury in respiratory epithelium of infected tnf-α-/- mice were alleviated. Thus, the pro-inflammatory cytokine TNF-α played a role in apoptosis and the respiratory epithelium injury in mouse lungs. Collectively, our study provides insight into the inflammatory injury induced by T. pyogenes and suggests that blocking NLR may be a potential therapeutic strategy against T. pyogenes infection.

Circulating inflammatory cytokines and hypertensive disorders of pregnancy: a two-sample Mendelian randomization study

Background

Hypertensive disorders of pregnancy (HDP) pose a significant risk to maternal and fetal well-being; however, the etiology and pathogenesis of HDP remain ambiguous. It is now widely acknowledged that inflammatory response and the immune system are closely related to HDP. Previous research has identified several inflammatory cytokines are associated with HDP. This study applied Mendelian randomization (MR) analysis to further assess causality.

Methods

Patients with HDP who participated in the MR analysis presented with four types of HDP: pre-eclampsia or eclampsia (PE); gestational hypertension (GH); pre-existing hypertension complicating pregnancy, childbirth and the puerperium (EH); and pre-eclampsia or poor fetal growth (PF). A two-sample MR analysis was used to analyze the data in the study. The causal relationship between exposure and outcome was analyzed with inverse variance weighting (IVW), MR Egger, weighted median, weighted mode, and simple mode methods, where IVW was the primary method employed.

Results

Our MR analysis demonstrated a reliable causative effect of Interleukin-9 (IL-9) and macrophage migration inhibitory factor (MIF) on reducing HDP risk, while macrophage inflammatory protein 1-beta (MIP1b), Interleukin-13 (IL-13), and Interleukin-16 (IL-16) were associated with promoting HDP risk.

Conclusions

This study demonstrated that IL-9, MIF, MIP1b, IL-13, and IL-16 may be cytokines associated with the etiology of HDP, and that a number of inflammatory cytokines are probably involved in the progression of HDP. Additionally, our study revealed that these inflammatory cytokines have causal associations with HDP and may likely be potential therapeutic targets for HDP.

Exploring the anti-inflammatory activity of sulforaphane

Dysregulation of innate immune responses can result in chronic inflammatory conditions. Glucocorticoids, the current frontline therapy, are effective immunosuppressive drugs but come with a trade-off of cumulative and serious side effects. Therefore, alternative drug options with improved safety profiles are urgently needed. Sulforaphane, a phytochemical derived from plants of the brassica family, is a potent inducer of phase II detoxification enzymes via nuclear factor-erythroid factor 2-related factor 2 (NRF2) signaling. Moreover, a growing body of evidence suggests additional diverse anti-inflammatory properties of sulforaphane through interactions with mediators of key signaling pathways and inflammatory cytokines. Multiple studies support a role for sulforaphane as a negative regulator of nuclear factor kappa-light chain enhancer of activated B cells (NF-κB) activation and subsequent cytokine release, inflammasome activation and direct regulation of the activity of macrophage migration inhibitory factor. Significantly, studies have also highlighted potential steroid-sparing activity for sulforaphane, suggesting that it may have potential as an adjunctive therapy for some inflammatory conditions. This review discusses published research on sulforaphane, including proposed mechanisms of action, and poses questions for future studies that might help progress our understanding of the potential clinical applications of this intriguing molecule.

Exploring the Role of CD74 and D-Dopachrome Tautomerase in COVID-19: Insights from Transcriptomic and Serum Analyses

The COVID-19 pandemic has posed a significant threat to public health worldwide. While some patients experience only mild symptoms or no symptoms at all, others develop severe illness, which can lead to death. The host immune response is believed to play a crucial role in determining disease severity. In this study, we investigated the involvement of CD74 and D-DT in COVID-19 patients with different disease severities, by employing an in silico analysis of a publicly available transcriptomic dataset and by measuring their serum levels by ELISA. Our results showed a significant increase in MIF levels in PBMCs from COVID-19 patients, as well as a significant increase in the D-DT levels in PBMCs. However, we observed no modulation in the serum levels of D-DT. We also observed a concordant reduction in the serum levels and PBMCs expression levels of CD74. Furthermore, we found a negative correlation between CD74 serum levels and IL-13. In conclusion, our study sheds light on the involvement of CD74 and D-DT in COVID-19, with potential implications for disease severity and treatment. Further studies are needed to fully elucidate the mechanisms underlying these observations and to explore the potential therapeutic value of targeting CD74 and IL-13 in COVID-19.

MIF Increases sFLT1 Expression in Early Uncomplicated Pregnancy and Preeclampsia

Insufficient immune tolerance during pregnancy is associated with pathological conditions such as preeclampsia (PE). Soluble fms-like tyrosine kinase-1 (sFLT1), which exerts a role in the late stage of PE, has shown its beneficial anti-inflammatory effects in inflammation-associated diseases. Macrophage migration inhibitory factor (MIF) was reported to upregulate sFLT1 production in experimental congenital diaphragmatic hernia. However, the placental sFLT1 expression in early uncomplicated pregnancy and whether MIF can regulate sFLT1 expression in uncomplicated and preeclamptic pregnancy are unclear. We collected first-trimester placentas and term placentas from uncomplicated and preeclamptic pregnancies to investigate sFLT1 and MIF expression in vivo. Primary cytotrophoblasts (CTBs) and a human trophoblast cell line (Bewo) were used to study the regulation of MIF on sFLT1 expression in vitro. In placentas from first-trimester pregnancy, we observed a high expression of sFLT1, specifically in extravillous trophoblasts (EVTs) and syncytiotrophoblast (STB) cells. MIF mRNA levels strongly correlated with sFLT1 expression in term placentas from preeclamptic pregnancies. In in vitro experiments, sFLT1 and MIF levels increased significantly in CTBs during their differentiation to EVTs and STBs, and MIF inhibitor (ISO-1) significantly reduced sFLT1 expression in a dose-dependent manner during this process. sFLT1 showed significant upregulation with increasing doses of MIF in Bewo cells. Our results show that sFLT1 is highly expressed at the maternal-fetal interface during early pregnancy and that MIF can increase sFLT1 expression in early uncomplicated pregnancy and PE, which suggests that sFLT1 plays an essential role in the modulation of inflammation in pregnancy.

Tumor-associated macrophages facilitate oral squamous cell carcinomas migration and invasion by MIF/NLRP3/IL-1β circuit: A crosstalk interrupted by melatonin

Invasion and migration are significant challenges for treatment of oral squamous cell carcinomas (OSCCs). Tumor-associated macrophages (TAMs) interact with cancer cells and are involved in tumor progression. Our recent study demonstrated that melatonin inhibits OSCC invasion and migration; however, the mechanism by which melatonin influences crosstalk between TAMs and OSCCs is poorly understood. In this study, a co-culture system was established to explore the interactions between human monocytic cells (THP-1 cells) and human tongue squamous cell carcinoma cells (SCC-15 cells). The results were verified using monocyte-derived macrophages (MDMs) isolated and differentiated from primary peripheral blood mononuclear cells. In vivo, assays were performed to confirm the anticancer effects of melatonin. SCC-15 cells co-cultured with THP-1 cells or MDMs exhibited increased migration and invasion, which was reversed by melatonin. Co-culture also increased the expression of macrophage migration inhibitory factor (MIF), CD40, CD163 and IL-1β, and these changes were also reversed by melatonin. Moreover, IL-1β secretion in THP-1 cells was MIF- and NLR family pyrin domain-containing 3 (NLRP3)-dependent, and treated with IL-1β enhanced the invasion and migration of SCC-15 cells. Furthermore, melatonin treatment significantly decreased tumor volumes and weights, and tumors from mice treated with melatonin had lower levels of MIF, NLRP3, and IL-1β than tumor from control mice. These results demonstrate that macrophages facilitate the progression of OSCCs by promoting the MIF/NLRP3/IL-1β signaling axis, which can be interrupted by melatonin. Therefore, melatonin could act as an alternative anticancer agent for OSCCs by targeting this signaling axis.

Unraveling the Complex Interconnection between Specific Inflammatory Signaling Pathways and Mechanisms Involved in HIV-Associated Colorectal Oncogenesis

The advancement of HIV treatment has led to increased life expectancy. However, people living with HIV (PLWH) are at a higher risk of developing colorectal cancers. Chronic inflammation has a key role in oncogenesis, affecting the initiation, promotion, transformation, and advancement of the disease. PLWH are prone to opportunistic infections that trigger inflammation. It has been documented that 15-20% of cancers are triggered by infections, and this percentage is expected to be increased in HIV co-infections. The incidence of parasitic infections such as helminths, with Ascariasis being the most common, is higher in HIV-infected individuals. Cancer cells and opportunistic infections drive a cascade of inflammatory responses which assist in evading immune surveillance, making them survive longer in the affected individuals. Their survival leads to a chronic inflammatory state which further increases the probability of oncogenesis. This review discusses the key inflammatory signaling pathways involved in disease pathogenesis in HIV-positive patients with colorectal cancers. The possibility of the involvement of co-infections in the advancement of the disease, along with highlights on signaling mechanisms that can potentially be utilized as therapeutic strategies to prevent oncogenesis or halt cancer progression, are addressed.

Elevated Serum Macrophage Migration Inhibitory Factor Levels are Associated With Major Depressive Disorder

Background

Previous studies have suggested the involvement of an activated inflammatory process in major depressive disorder (MDD), as altered expression of inflammatory cytokines is observed in depression. This alteration can be the cause or a consequence of MDD. However, acknowledging inflammatory cytokines as prospective biomarkers would aid in diagnosing or guiding better therapeutic options. Therefore, we designed this study to assess the macrophage migration inhibitory factor (MIF) in depression.

Method

We collected blood samples from 115 MDD patients and 113 healthy controls (HCs) matched by age and sex. MDD patients were diagnosed by a qualified psychiatrist based on the symptoms mentioned in the diagnostic and statistical manual of mental disorders (DSM-5). We applied the Hamilton depression (Ham-D) rating scale to assess the severity of depression. We assessed serum levels of MIF using ELISA kit (Boster Bio, USA).

Result

We detected increased serum MIF levels in MDD patients compared to HCs (6.15 ± 0.23 ng/mL vs 3.95 ± 0.21 ng/mL, P < 0.001). Moreover, this increase is more among female patients than female controls. Also, we noticed a positive correlation between altered MIF levels and the Ham-D scores (r = 0.233; P = 0.012), where we found that patients who scored higher on the Ham-D scale had higher MIF levels in serum. Moreover, the area under the curve (AUC) of receiver operating characteristic (ROC) curve represented the good diagnostic performance of altered serum MIF.

Conclusion

Our study findings indicate the association of pro-inflammatory cytokine MIF in the pathophysiology of depression as we identified elevated serum MIF levels in depressive patients compared to HCs. However, more researches are required to confirm whether this alteration of cytokine is the causative factor or a consequence of depression. We recommend conducting further studies to understand the pattern of this alteration of MIF levels in MDD patients.

Macrophage migration inhibitory factor promotes glucocorticoid resistance of neutrophilic inflammation in a murine model of severe asthma

Background

Severe neutrophilic asthma is resistant to treatment with glucocorticoids. The immunomodulatory protein macrophage migration inhibitory factor (MIF) promotes neutrophil recruitment to the lung and antagonises responses to glucocorticoids. We hypothesised that MIF promotes glucocorticoid resistance of neutrophilic inflammation in severe asthma.

Methods

We examined whether sputum MIF protein correlated with clinical and molecular characteristics of severe neutrophilic asthma in the Unbiased Biomarkers for the Prediction of Respiratory Disease Outcomes (U-BIOPRED) cohort. We also investigated whether MIF regulates neutrophilic inflammation and glucocorticoid responsiveness in a murine model of severe asthma in vivo.

Results

MIF protein levels positively correlated with the number of exacerbations in the previous year, sputum neutrophils and oral corticosteroid use across all U-BIOPRED subjects. Further analysis of MIF protein expression according to U-BIOPRED-defined transcriptomic-associated clusters (TACs) revealed increased MIF protein and a corresponding decrease in annexin-A1 protein in TAC2, which is most closely associated with airway neutrophilia and NLRP3 inflammasome activation. In a murine model of severe asthma, treatment with the MIF antagonist ISO-1 significantly inhibited neutrophilic inflammation and increased glucocorticoid responsiveness. Coimmunoprecipitation studies using lung tissue lysates demonstrated that MIF directly interacts with and cleaves annexin-A1, potentially reducing its biological activity.

Conclusion

Our data suggest that MIF promotes glucocorticoid-resistance of neutrophilic inflammation by reducing the biological activity of annexin-A1, a potent glucocorticoid-regulated protein that inhibits neutrophil accumulation at sites of inflammation. This represents a previously unrecognised role for MIF in the regulation of inflammation and points to MIF as a potential therapeutic target for the management of severe neutrophilic asthma.

Macrophage Migration Inhibitory Factor (MIF) Promotes Increased Proportions of the Highly Permissive Th17-like Cell Profile during HIV Infection

In this study, we evaluate the role of the MIF/CD74 axis in the functionality of CD4⁺ T lymphocytes (CD4TL) during HIV infection. MDMs from healthy donors were infected with a R5-tropic or Transmitted/Founder (T/F) HIV strain. At day 11 post-MDM infection, allogeneic co-cultures with uninfected CD4TLs plus MIF stimulus were performed. Cytokine production was evaluated by ELISA. MIF plasma levels of people with HIV (PWH) were evaluated by ELISA. The phenotype and infection rate of CD4TLs from PWH were analyzed after MIF stimulus. Intracellular cytokines and transcription factors were evaluated by flow cytometry. Data were analyzed by parametric or non-parametric methods. The MIF stimulation of HIV-infected MDMs induced an increased expression of IL-6, IL-1β and IL-8. In CD4TL/MDM co-cultures, the MIF treatment increased IL-17A/RORγt-expressing CD4TLs. Higher concentrations of IL-17A in supernatants were also observed. These results were recapitulated using transmitted/founder (T/F) HIV-1 strains. The MIF treatment appeared to affect memory CD4TLs more than naïve CD4TLs. MIF blocking showed a negative impact on IL17A⁺CD4TL proportions. Higher MIF concentrations in PWH-derived plasma were correlated with higher IL-17A⁺CD4TL percentages. Finally, MIF stimulation in PWH-derived PBMCs led to an increase in Th17-like population. MIF may contribute to viral pathogenesis by generating a microenvironment enriched in activating mediators and Th17-like CD4TLs, which are known to be highly susceptible to HIV-1 infection and relevant to viral persistence. These observations establish a basis for considering MIF as a possible therapeutic target.

Investigating immunoregulatory effects of myeloid cell autophagy in acute and chronic inflammation

Studies have highlighted a critical role for autophagy in the regulation of multiple cytokines. Autophagy inhibits the release of interleukin (IL)‐1 family cytokines, including IL‐1α, IL‐1β and IL‐18, by myeloid cells. This, in turn, impacts the release of other cytokines by myeloid cells, as well as other cells of the immune system, including IL‐22, IL‐23, IL‐17 and interferon‐γ. Here, we assessed the impact of genetic depletion of the autophagy gene Atg7 in myeloid cells on acute and chronic inflammation. In a model of acute lipopolysaccharide‐induced endotoxemia, loss of autophagy in myeloid cells resulted in increased release of proinflammatory cytokines, both locally and systemically. By contrast, loss of Atg7 in myeloid cells in the Lyn^−/− model of lupus‐like autoimmunity resulted in reduced systemic release of IL‐6 and IL‐10, with no effects on other cytokines observed. In addition, Lyn^−/− mice with autophagy‐deficient myeloid cells showed reduced expression of autoantibodies relevant to systemic lupus erythematosus, including anti‐histone and anti‐Smith protein. In vitro, loss of autophagy, through pharmacological inhibition or small interfering RNA against Becn1, inhibited IL‐10 release by human and mouse myeloid cells. This effect was evident at the level of Il10 messenger RNA expression. Our data highlight potentially important differences in the role of myeloid cell autophagy in acute and chronic inflammation and demonstrate a direct role for autophagy in the production and release of IL‐10 by macrophages.

The multifaceted roles of NLRP3-modulating proteins in virus infection

The innate immune response to viruses is critical for the correct establishment of protective adaptive immunity. Amongst the many pathways involved, the NLRP3 [nucleotide-binding oligomerisation domain (NOD)-like receptor protein 3 (NLRP3)] inflammasome has received considerable attention, particularly in the context of immunity and pathogenesis during infection with influenza A (IAV) and SARS-CoV-2, the causative agent of COVID-19. Activation of the NLRP3 inflammasome results in the secretion of the proinflammatory cytokines IL-1β and IL-18, commonly coupled with pyroptotic cell death. While this mechanism is protective and key to host defense, aberrant NLRP3 inflammasome activation causes a hyperinflammatory response and excessive release of cytokines, both locally and systemically. Here, we discuss key molecules in the NLRP3 pathway that have also been shown to have significant roles in innate and adaptive immunity to viruses, including DEAD box helicase X-linked (DDX3X), vimentin and macrophage migration inhibitory factor (MIF). We also discuss the clinical opportunities to suppress NLRP3-mediated inflammation and reduce disease severity.

Association of Macrophage Migration Inhibitory Factor Gene –173 G/C Polymorphism (rs755622) with Familial Mediterranean Fever in Children

Objectives The aim of this study was to identify the genotypic analysis and allele frequencies of the –173 G/C polymorphism in the macrophage migration inhibitory factor (MIF) gene in children diagnosed with familial Mediterranean fever (FMF).

Methods The study included 98 children who were diagnosed with FMF according to the Tel Hashomer criteria and one hundred and 57 healthy children as the control group. Genotyping was done for a polymorphism in a promoter region of the MIF gene (G/C at position –173).

Results The relationship of FMF prevalence and –173 G/C genotype of the MIF gene was statistically significant. Individuals with the CC genotype seem to be predisposed to FMF.

Conclusion The C/C polymorphism at position –173 of the MIF gene could be associated with excessive inflammation and immune response and can lead to susceptibility to FMF

TRPM2 deficiency in mice protects against atherosclerosis by inhibiting TRPM2-CD36 inflammatory axis in macrophages

Atherosclerosis is the major cause of ischemic heart disease and stroke, the leading causes of mortality worldwide. The central pathological features of atherosclerosis include macrophage infiltration and foam cell formation. However, the detailed mechanisms regulating these two processes remain unclear. Here we show that oxidative stress-activated Ca²⁺-permeable transient receptor potential melastatin 2 (TRPM2) plays a critical role in atherogenesis. Both global and macrophage-specific Trpm2 deletion protect Apoe^−/− mice against atherosclerosis. Trpm2 deficiency reduces oxidized low-density lipoprotein (oxLDL) uptake by macrophages, thereby minimizing macrophage infiltration, foam cell formation and inflammatory responses. Activation of the oxLDL receptor CD36 induces TRPM2 activity, and vice versa. In cultured macrophages, TRPM2 is activated by CD36 ligands oxLDL and thrombospondin-1 (TSP1), and deleting Trpm2 or inhibiting TRPM2 activity suppresses the activation of CD36 signaling cascade induced by oxLDL and TSP1. Our findings establish the TRPM2-CD36 axis as a molecular mechanism underlying atherogenesis, and suggest TRPM2 as a potential therapeutic target for atherosclerosis.

Nematode Orthologs of Macrophage Migration Inhibitory Factor (MIF) as Modulators of the Host Immune Response and Potential Therapeutic Targets

One of the adaptations of nematodes, which allows long-term survival in the host, is the production of proteins with immunomodulatory properties. The parasites secrete numerous homologs of human immune mediators, such as macrophage migration inhibitory factor (MIF), which is a substantial regulator of the inflammatory immune response. Homologs of mammalian MIF have been recognized in many species of nematode parasites, but their role has not been fully understood. The application of molecular biology and genetic engineering methods, including the production of recombinant proteins, has enabled better characterization of their structure and properties. This review provides insight into the current state of knowledge on MIF homologs produced by nematodes, as well as their structure, enzymatic activity, tissue expression pattern, impact on the host immune system, and potential use in the treatment of parasitic, inflammatory, and autoimmune diseases.

Macrophage migration inhibitory factor is overproduced through EGR1 in TET2low resting monocytes

Somatic mutation in TET2 gene is one of the most common clonal genetic events detected in age-related clonal hematopoiesis as well as in chronic myelomonocytic leukemia (CMML). In addition to being a pre-malignant state, TET2 mutated clones are associated with an increased risk of death from cardiovascular disease, which could involve cytokine/chemokine overproduction by monocytic cells. Here, we show in mice and in human cells that, in the absence of any inflammatory challenge, TET2 downregulation promotes the production of MIF (macrophage migration inhibitory factor), a pivotal mediator of atherosclerotic lesion formation. In healthy monocytes, TET2 is recruited to MIF promoter and interacts with the transcription factor EGR1 and histone deacetylases. Disruption of these interactions as a consequence of TET2-decreased expression favors EGR1-driven transcription of MIF gene and its secretion. MIF favors monocytic differentiation of myeloid progenitors. These results designate MIF as a chronically overproduced chemokine and a potential therapeutic target in patients with clonal TET2 downregulation in myeloid cells.

To improve our understanding of the pathological role of TET2 mutations, Pronier, Imanci et al. use mice and human cells to show that TET2 downregulation promotes the production of macrophage migration inhibitory factor (MIF). In addition they show that whilst TET2 is recruited to the MIF promoter in healthy monocytes, decreased TET2 expression results in chronic overproduction of MIF - suggesting that MIF signaling could therefore constitute a potential therapeutic target for conditions associated with TET2 mutations.

Macrophage migration inhibitory factor family proteins are multitasking cytokines in tissue injury

The family of macrophage migration inhibitory factor (MIF) proteins in humans consist of MIF, its functional homolog D-dopachrome tautomerase (D-DT, also known as MIF-2) and the relatively unknown protein named DDT-like (DDTL). MIF is a pleiotropic cytokine with multiple properties in tissue homeostasis and pathology. MIF was initially found to associate with inflammatory responses and therefore established a reputation as a pro-inflammatory cytokine. However, increasing evidence demonstrates that MIF influences many different intra- and extracellular molecular processes important for the maintenance of cellular homeostasis, such as promotion of cellular survival, antioxidant signaling, and wound repair. In contrast, studies on D-DT are scarce and on DDTL almost nonexistent and their functions remain to be further investigated as it is yet unclear how similar they are compared to MIF. Importantly, the many and sometimes opposing functions of MIF suggest that targeting MIF therapeutically should be considered carefully, taking into account timing and severity of tissue injury. In this review, we focus on the latest discoveries regarding the role of MIF family members in tissue injury, inflammation and repair, and highlight the possibilities of interventions with therapeutics targeting or mimicking MIF family proteins.

The IL-25-dependent tuft cell circuit driven by intestinal helminths requires macrophage migration inhibitory factor (MIF)

Macrophage migration inhibitory factor (MIF) is a key innate immune mediator with chemokine- and cytokine-like properties in the inflammatory pathway. While its actions on macrophages are well-studied, its effects on other cell types are less understood. Here we report that MIF is required for expansion of intestinal tuft cells during infection with the helminth Nippostrongylus brasiliensis. MIF-deficient mice show defective innate responses following infection, lacking intestinal epithelial tuft cell hyperplasia or upregulation of goblet cell RELMβ, and fail to expand eosinophil, type 2 innate lymphoid cell (ILC2) and macrophage (M2) populations. Similar effects were observed in MIF-sufficient wild-type mice given the MIF inhibitor 4-IPP. MIF had no direct effect on epithelial cells in organoid cultures, and MIF-deficient intestinal stem cells could generate tuft cells in vitro in the presence of type 2 cytokines. In vivo the lack of MIF could be fully compensated by administration of IL-25, restoring tuft cell differentiation and goblet cell expression of RELM-β, demonstrating its requirement upstream of the ILC2-tuft cell circuit. Both ILC2s and macrophages expressed the MIF receptor CXCR4, indicating that MIF may act as an essential co-factor on both cell types to activate responses to IL-25 in helminth infection.

Canonical (CD74/CD44) and Non-Canonical (CXCR2, 4 and 7) MIF Receptors Are Differentially Expressed in Rheumatoid Arthritis Patients Evaluated by DAS28-ESR

Macrophage migration inhibitory factor (MIF) significantly contributes to rheumatoid arthritis (RA) pathogenesis. We aimed to evaluate the canonical (CD74/CD44) and non-canonical MIF receptors (CXCR2,4 and 7) expression and sCD74 to establish their association with RA clinical activity according to DAS28-ESR.

METHODOLOGY

101 RA patients with different clinical activities (remission (n = 27), low (n = 16), moderate (n = 35) and high (n = 23)) and 9 control subjects (CS) were included. Expression was evaluated by flow cytometry and levels of soluble CD74 (sCD74) by ELISA. Data analysis was performed with FlowJov10.0, STATAv12.0, and GraphPad Prism v7.0.

RESULTS

According to disease activity, CXCR7 expression (percentage of expression and mean fluorescence intensity (MFI)) was higher in granulocytes from patients in remission, while the expression of CXCR4 was higher in patients with high disease activity (p < 0.05). The expression of CD74 was higher in B cells (p < 0.05) and monocytes (p < 0.01) from patients in remission. Regarding sCD74 levels these were higher in patients with high disease activity when compared to those in remission (p <0.05).

CONCLUSIONS

The results support the need for further study of the role of sCD74 as a soluble MIF decoy receptor, sequestering it to negatively regulate MIF signaling though its membrane receptors. The expression patterns of CXCR4 and CXCR7 show that the latter is a scavenger-type receptor that prevents endocytosis and even degradation of CXCR4 under inflammatory conditions.

Immunopathophysiology of Juvenile Spondyloarthritis (jSpA): The "Out of the Box" View on Epigenetics, Neuroendocrine Pathways and Role of the Macrophage Migration Inhibitory Factor (MIF)

Juvenile spondyloarthritis (jSpA) is a an umbrella term for heterogeneous group of related seronegative inflammatory disorders sharing common symptoms. Although it mainly affects children and adolescents, it often remains active during adulthood. Genetic and environmental factors are involved in its occurrence, although the exact underlying immunopathophysiology remains incompletely elucidated. Accumulated evidence suggests that, in affected patients, subclinical gut inflammation caused by intestinal dysbiosis, is pivotal to the future development of synovial-entheseal complex inflammation. While the predominant role of IL17/23 axis, TNF-α, and IL-7 in the pathophysiology of SpA, including jSpA, is firmly established, the role of the cytokine macrophage migration inhibitory factor (MIF) is generally overlooked. The purpose of this review is to discuss and emphasize the role of epigenetics, neuroendocrine pathways and the hypothalamic-pituitary (HPA) axis, and to propose a novel hypothesis of the role of decreased NLRP3 gene expression and possibly MIF in the early phases of jSpA development. The decreased NLRP3 gene expression in the latter, due to hypomethylation of promotor site, is (one of) the cause for inflammasome malfunction leading to gut dysbiosis observed in patients with early jSpA. In addition, we highlight the role of MIF in the complex innate, adaptive cellular and main effector cytokine network, Finally, since treatment of advanced bone pathology in SpA remains an unmet clinical need, I suggest possible new drug targets with the aim to ultimately improve treatment efficacy and long-term outcome of jSpA patients.

Functional Characterization of the Wheat Macrophage Migration Inhibitory Factor TaMIF1 in Wheat-Stripe Rust (Puccinia striiformis) Interaction

Simple Summary

There have been many breakthroughs in MIF function and mechanism investigation in vertebrates, but it has rarely been studied in plants. Here, we aimed to characterize the function of MIF in wheat and its potential role in Wheat-Stripe rust interaction. We showed that wheat MIF has some similarities with that MIF in vertebrates, such as subcellular localization in both the cytosol and nuclei, as well as significant tautomerase activity, and both can inhibit Bax-induced programmed cell death. In the wheat–Pst interaction, TaMIF1 is upregulated during Pst infection. Silencing TaMIF1 decreased Pst infection of wheat tissues, and the accumulation of ROS was increased in TaMIF1-silenced wheat leaves, which hinted that TaMIF1 mainly modulates the ROS signaling and then alters the subsequent immune responses. The function characterization of TaMIF1 provides significant insight into the role of MIFs across kingdoms and helpful in-depth functional mechanism analysis on these proteins.

Abstract

Macrophage migration inhibitory factor (MIF), named for its role in inhibiting macrophage/monocyte migration, has multiple functions in modulation of inflammation, cell proliferation, angiogenesis, and tumorigenesis in vertebrates. Although homologs of this gene can be found in plants, the function of MIF in plants remains obscure. Here, we characterized TaMIF1 in Triticum aestivum resembling the MIF secreted from Homo sapiens. Transcript analysis revealed that TaMIF1 responded to stripe rust infection of wheat and was upregulated during the infection stage. TaMIF1 was localized to both the cytosol and nuclei in wheat mesophyll protoplast. Additionally, TaMIF1 possessed significant tautomerase activity, indicating conservation of MIFs across kingdoms. Agrobacterium tumefaciens infiltration assay demonstrated that TaMIF1 was capable of suppressing programmed cell death hinting its role in plant immunity. Heterologous expression of TaMIF1 increased fission yeast sensitivity to oxidative stress. Silencing TaMIF1 decreased the susceptibility of wheat to Pst seemingly through increasing reactive oxygen species accumulation. In conclusion, functions of the TaMIF1 were investigated in this study, which provides significant insight into understanding the role of MIFs across kingdoms.

Overexpression of D-dopachrome tautomerase increases ultraviolet B irradiation-induced skin tumorigenesis in mice

Ultraviolet irradiation (UV) exposure is the leading factor underlying the development of skin malignancies. D-dopachrome tautomerase (D-DT), a functional homolog of macrophage migration inhibitory factor (MIF), has functional similarities to MIF. However, its role, unlike the role of MIF in photocarcinogenesis, is unknown. We therefore explored the role of D-DT in photocarcinogenesis by developing D-DT transgenic (D-DT Tg) mice and provided a research model for future studies targeting D-DT. Chronic UVB exposure accelerated tumor development in D-DT Tg mice compared with wild-type (WT) mice, with a higher incidence of tumors observed in D-DT Tg mice than in WT mice. In D-DT Tg irradiated mouse keratinocytes, the p53, PUMA, and Bax expression was lower than that in WT mice. These results indicate that D-DT Tg overexpression confers prevention against UVB-induced apoptosis in keratinocytes. Taken together, these findings support D-DT as a functionally important cytokine in photocarcinogenesis and potential therapeutic target for the prevention of photocarcinogenesis.

Advances in immunological research of amphioxus

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

Major signaling pathways and key mediators of macrophages in acute kidney injury (Review)

Acute kidney injury (AKI) has become a global public health problem with high morbidity and mortality rates, as well as high healthcare costs. Immune cells, particularly macrophages, which regulate tissue development, destroy pathogens, control homeostasis and repair wounds, play crucial and complex roles in AKI. In various types of AKI, numerous rapidly recruited monocytes and tissue-resident macrophages act in a coordinated manner. Thus, elucidating the phenotypic and functional characteristics of macrophages in AKI is essential for identifying potential therapeutic targets. Macrophage-sensing mediators and macrophage-derived mediators participate in the major macrophage-related signaling pathways in AKI, which regulate macrophage polarization and determine disease progression. In conclusion, macrophages change their roles and regulatory mechanisms during the occurrence and development of AKI. The aim of the present review was to contribute to an improved understanding of AKI and to the identification of novel therapeutic targets for this condition.

Targeting Macrophage Migration Inhibitory Factor in Acute Pancreatitis and Pancreatic Cancer

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

Macrophage migration inhibitory factor in human early pregnancy events and association with placental pathologies

Macrophage migration inhibitory factor (MIF) is a versatile cytokine acting as an important regulator of innate and adaptive immunity and implicated in many physiological and pathological processes. It is abundantly expressed at the feto-maternal interface and proposed to have a role in establishing and maintaining a healthy pregnancy. This review presents the current literature data regarding the MIF role in early pregnancy events and its association with some of the placental pathological conditions, including infection, preeclampsia, gestational diabetes mellitus and choriocarcinoma. General information regarding MIF structure and function is followed by an overview of its expression in reproductive tissues and in pregnancy. Futher, we discuss MIF's involvement in the survival of decidual stromal cells, placenta of the first trimester of pregnancy, and in trophoblast cell functions studied in vitro. Current findings associating this cytokine to placental infection, preeclampsia, gestational diabetes mellitus and choriocarcinoma are presented in the final part.

Role of the Macrophage Migration Inhibitory Factor in the Pathophysiology of Pre-Eclampsia

Proinflammatory cytokines are produced in pregnancy in response to the invading pathogens and/or nonmicrobial causes such as damage-associated molecules and embryonic semi-allogenic antigens. While inflammation is essential for a successful pregnancy, an excessive inflammatory response is implicated in several pathologies including pre-eclampsia (PE). This review focuses on the proinflammatory cytokine macrophage migration inhibitory factor (MIF), a critical regulator of the innate immune response and a major player of processes allowing normal placental development. PE is a severe pregnancy-related syndrome characterized by exaggerated inflammatory response and generalized endothelial damage. In some cases, usually of early onset, it originates from a maldevelopment of the placenta, and is associated with intrauterine growth restriction (IUGR) (placental PE). In other cases, usually of late onset, pre-pregnancy maternal diseases represent risk factors for the development of the disease (maternal PE). Available data suggest that low MIF production in early pregnancy could contribute to the abnormal placentation. The resulting placental hypoxia in later pregnancy could produce high release of MIF in maternal serum typical of placental PE. More studies are needed to understand the role of MIF, if any, in maternal PE.

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.

IL-10 and class 1 histone deacetylases act synergistically and independently on the secretion of proinflammatory mediators in alveolar macrophages

Introduction

Anti-inflammatory cytokine IL-10 suppresses pro-inflammatory IL-12b expression after Lipopolysaccharide (LPS) stimulation in colonic macrophages, as part of the innate immunity Toll-Like Receptor (TLR)-NF-κB activation system. This homeostatic mechanism limits excess inflammation in the intestinal mucosa, as it constantly interacts with the gut flora. This effect is reversed with Histone Deacetylase 3 (HDAC3), a class I HDAC, siRNA, suggesting it is mediated through HDAC3. Given alveolar macrophages’ prominent role in Acute Lung Injury (ALI), we aim to determine whether a similar regulatory mechanism exists in the typically sterile pulmonary microenvironment.

Methods

Levels of mRNA and protein for IL-10, and IL-12b were determined by qPCR and ELISA/Western Blot respectively in naïve and LPS-stimulated alveolar macrophages. Expression of the NF-κB intermediaries was also similarly assessed. Experiments were repeated with AS101 (an IL-10 protein synthesis inhibitor), MS-275 (a selective class 1 HDAC inhibitor), or both.

Results

LPS stimulation upregulated all proinflammatory mediators assayed in this study. In the presence of LPS, inhibition of IL-10 and/or class 1 HDACs resulted in both synergistic and independent effects on these signaling molecules. Quantitative reverse-transcriptase PCR on key components of the TLR4 signaling cascade demonstrated significant diversity in IL-10 and related gene expression in the presence of LPS. Inhibition of IL-10 secretion and/or class 1 HDACs in the presence of LPS independently affected the transcription of MyD88, IRAK1, Rela and the NF-κB p50 subunit. Interestingly, by quantitative ELISA inhibition of IL-10 secretion and/or class 1 HDACs in the presence of LPS independently affected the secretion of not only IL-10, IL-12b, and TNFα, but also proinflammatory mediators CXCL2, IL-6, and MIF. These results suggest that IL-10 and class 1 HDAC activity regulate both independent and synergistic mechanisms of proinflammatory cytokine/chemokine signaling.

Conclusions

Alveolar macrophages after inflammatory stimulation upregulate both IL-10 and IL-12b production, in a highly class 1 HDAC-dependent manner. Class 1 HDACs appear to help maintain the balance between the pro- and anti-inflammatory IL-12b and IL-10 respectively. Class 1 HDACs may be considered as targets for the macrophage-initiated pulmonary inflammation in ALI in a preclinical setting.

Macrophage Migration Inhibitory Factor (MIF) and Its Homologue d-Dopachrome Tautomerase (DDT) Inversely Correlate with Inflammation in Discoid Lupus Erythematosus

Discoid Lupus Erythematosus (DLE) is a chronic cutaneous disease of unknown etiology and of immunoinflammatory origin that is characterized by inflammatory plaques and may lead to disfiguring scarring and skin atrophy. Current treatments are limited, with a large proportion of patients either poorly or not responsive, which makes DLE an unmet medical need. Macrophage migration inhibitory factor (MIF) is the prototype of a pleiotropic family of cytokine that also includes the recently discovered homologue D-dopachrome tautomerase (DDT) or MIF2. MIF and DDT/MIF-2 exert several biological properties, primarily, but not exclusively of a proinflammatory nature. MIF and DDT have been suggested to play a key role in the pathogenesis of several autoimmune diseases, such as multiple sclerosis and type 1 diabetes, as well as in the development and progression of certain forms of cancers. In the present study, we have performed an immunohistochemistry analysis for the evaluation of MIF in DLE lesions and normal skin. We found high levels of MIF in the basal layer of the epidermis as well as in the cutaneous appendage (eccrine glands and sebocytes) of normal skin. In DLE lesions, we observed a significant negative correlation between the expression of MIF and the severity of inflammation. In addition, we performed an analysis of MIF and DDT expression levels in the skin of DLE patients in a publicly available microarray dataset. Interestingly, while these in silico data only evidenced a trend toward reduced levels of MIF, they demonstrated a significant pattern of expression and correlation of DDT with inflammatory infiltrates in DLE skins. Overall, our data support a protective role for endogenous MIF and possibly DDT in the regulation of homeostasis and inflammation in the skin and open up novel avenues for the treatment of DLE.

Protective effect of ISO-1 with inhibition of RIPK3 up-regulation and neutrophilic accumulation on acetaminophen-induced liver injury in mice

Overdose use of acetaminophen (APAP) often occurs a severe liver injury, and its liver injury is lethal in some cases. Macrophage migration inhibitory factor (MIF) is expressed in a variety of cells and has multifunctional roles. However, the role of MIF in APAP-induced liver injury has not been fully investigated. In this study, we investigated whether treatment with (S,R)-3-(4-hydroxyphenil)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1), a MIF inhibitor, protected mice from acute APAP-induced liver injury. Acute liver injury was induced by injection of APAP (300 mg/kg body weight). Mice were treated with a single injection of ISO-1(15 mg/kg body weight) 1 h (h) before APAP administration. Histological, biochemical and molecular analyses were performed in liver of mice 12 h after APAP administration. ISO-1 remarkably improved the histological findings of APAP-induced liver injury in mice. The increases in serum levels of alanine aminotransferase (ALT), and macrophage inflammatory protein-2 (MIP-2) by APAP were inhibited by ISO-1. In addition, ISO-1 reduced the increased number of the myeloperoxidase-staining cells and that of TUNEL-positive staining cells in the liver of mice with APAP-induced liver injury. Up-regulation of hepatic receptor interacting protein kinase (RIPK)3 and heat shock protein70 by APAP was suppressed in the liver of mice given ISO-1. These results provide the additional evidence that inhibition of MIF activity may be clinically effective for treatment of acute APAP-induced liver injury.

Expression profile of macrophage migration inhibitory factor in periodontitis

OBJECTIVE

Macrophage migration inhibitory factor (MIF) is a pivotal mediator of host innate immunity and influences the development of several inflammatory diseases. The role of MIF in periodontitis is unclear.

METHODS

Eighteen periodontally healthy volunteers and 18 patients with stage III or IV periodontitis were enrolled. Blood samples and gingival tissues were collected from all individuals. The serum concentrations of MIF and MCP-1 were measured by ELISA. The protein and mRNA levels of MIF and MCP-1 in gingival tissue were evaluated by immunohistochemical staining and quantitative PCR. The levels of secreted MIF and MCP-1, as well as their mRNA levels, were determined by ELISA and quantitative PCR in oral epithelial cells infected with Porphyromonas gingivalis.

RESULTS

After adjusting for age, the level of MCP-1 was significantly higher in the serum and gingival tissue of periodontitis patients, as well as in infected epithelial cells. The serum concentration of MIF was increased in periodontitis patients (15.25 ± 2.16 ng/mL, P < 0.05) compared to healthy controls (10.43 ± 1.02 ng/mL). Increased MIF immunoreactivity was found in gingival epithelial tissue but not in the gingival connective tissue of periodontitis patients. The secretion of MIF was 3.82-fold higher in the supernatant of infected cells than in the supernatant of control (P < 0.01). No increase in the MIF mRNA level was found in either gingival tissue or epithelial cells.

CONCLUSIONS

Based on our limited evidence, we showed the level of MIF was related to periodontal conditions. P. gingivalis may contribute to the development and progression of periodontitis through MIF.

Single-cell analysis of developing and azoospermia human testicles reveals central role of Sertoli cells

Clinical efficacy of treatments against non-obstructive azoospermia (NOA), which affects 1% of men, are currently limited by the incomplete understanding of NOA pathogenesis and normal spermatogenic microenvironment. Here, we profile >80,000 human testicular single-cell transcriptomes from 10 healthy donors spanning the range from infant to adult and 7 NOA patients. We show that Sertoli cells, which form the scaffold in the testicular microenvironment, are severely damaged in NOA patients and identify the roadmap of Sertoli cell maturation. Notably, Sertoli cells of patients with congenital causes (Klinefelter syndrome and Y chromosome microdeletions) are mature, but exhibit abnormal immune responses, while the cells in idiopathic NOA (iNOA) are physiologically immature. Furthermore, we find that inhibition of Wnt signaling promotes the maturation of Sertoli cells from iNOA patients, allowing these cells to regain their ability to support germ cell survival. We provide a novel perspective on the development of diagnostic methods and therapeutic targets for NOA.

Non-obstructive azoospermia affects 1% of men. Here, authors perform single-cell transcriptomic analysis of human testicular cells from healthy donors and non-obstructive azoospermia patients and find that inhibition of Wnt signaling promotes the maturation of Sertoli cells from 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.

Atypical Membrane-Anchored Cytokine MIF in a Marine Dinoflagellate

Macrophage Migration Inhibitory Factors (MIF) are pivotal cytokines/chemokines for vertebrate immune systems. MIFs are typically soluble single-domain proteins that are conserved across plant, fungal, protist, and metazoan kingdoms, but their functions have not been determined in most phylogenetic groups. Here, we describe an atypical multidomain MIF protein. The marine dinoflagellate Lingulodinium polyedra produces a transmembrane protein with an extra-cytoplasmic MIF domain, which localizes to cell-wall-associated membranes and vesicular bodies. This protein is also present in the membranes of extracellular vesicles accumulating at the secretory pores of the cells. Upon exposure to biotic stress, L. polyedra exhibits reduced expression of the MIF gene and reduced abundance of the surface-associated protein. The presence of LpMIF in the membranes of secreted extracellular vesicles evokes the fascinating possibility that LpMIF may participate in intercellular communication and/or interactions between free-living organisms in multispecies planktonic communities.

Role of MIF Cytokine/CD74 Receptor Pathway in Protecting Against Injury and Promoting Repair

Wound healing after an injury is essential for life. An in-depth understanding of the healing process is necessary to ultimately improve the currently limited treatment options for patients suffering as a result of damage to various organs and tissues. Injuries, even the most minor, trigger an inflammatory response that protects the host and activates repair pathways. In recent years, substantial progress has been made in delineating the mechanisms by which inflammatory cytokines and their receptors facilitate tissue repair and regeneration. This mini review focuses on emerging literature on the role of the cytokine macrophage migration inhibitory factor (MIF) and its cell membrane receptor CD74, in protecting against injury and promoting healing in different parts of the body.

MiMIF-2 Effector of Meloidogyne incognita Exhibited Enzyme Activities and Potential Roles in Plant Salicylic Acid Synthesis

Plant-parasitic nematodes secrete a series of effectors to promote parasitism by modulating host immunity, but the detailed molecular mechanism is ambiguous. Animal parasites secrete macrophage migration inhibitory factor (MIF)-like proteins for evasion of host immune systems, in which their biochemical activities play essential roles. Previous research demonstrated that MiMIF-2 effector was secreted by Meloidogyne incognita and modulated host immunity by interacting with annexins. In this study, we show that MiMIF-2 had tautomerase activity and protected nematodes against H₂O₂ damage. MiMIF-2 expression not only decreased the amount of H₂O₂ generation during nematode infection in Arabidopsis, but also suppressed Bax-induced cell death by inhibiting reactive oxygen species burst in Nicotiana benthamiana. Further, RNA-seq transcriptome analysis and RT-qPCR showed that the expression of some heat-shock proteins was down regulated in MiMIF-2 transgenic Arabidopsis. After treatment with flg22, RNA-seq transcriptome analysis indicated that the differentially expressed genes in MiMIF-2 expressing Arabidopsis were pointed to plant hormone signal transduction, compound metabolism and plant defense. RT-qPCR and metabolomic results confirmed that salicylic acid (SA) related marker genes and SA content were significantly decreased. Our results provide a comprehensive understanding of how MiMIF-2 modulates plant immunity and broaden knowledge of the intricate relationship between M. incognita and host plants.

Knockout of macrophage migration inhibitory factor accentuates side-stream smoke exposure-induced myocardial contractile dysfunction through dysregulated mitophagy

Second hand smoke exposure increases the prevalence of chronic diseases partly attributed to inflammatory responses. Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, is involved in the pathogenesis of multiple diseases although its role in second hand smoke exposure-induced cardiac anomalies remains elusive. This study evaluated the impact of MIF knockout on side-stream smoke exposure-induced cardiac pathology and underlying mechanisms. Adult WT and MIF knockout (MIFKO) mice were placed in a chamber exposed to cigarette smoke for 1 h daily for 60 consecutive days. Echocardiographic, cardiomyocyte function and intracellular Ca²⁺ handling were evaluated. Autophagy, mitophagy and apoptosis were examined using western blot. DHE staining was used to evaluate superoxide anion (O₂^-) generation. Masson trichrome staining was employed to assess interstitial fibrosis. Our data revealed that MIF knockout accentuated side-stream smoke-induced cardiac anomalies in fractional shortening, cardiomyocyte function, intracellular Ca²⁺ homeostasis, myocardial ultrastructure and mitochondrial content along with overt apoptosis and O₂^- generation. In addition, unfavorable effects of side-stream smoke were accompanied by excessive formation of autophagolysosome and elevated TFEB, the effect of which was exacerbated by MIF knockout. Recombinant MIF rescued smoke extract-induced myopathic anomalies through promoting AMPK activation, mitophagy and lysosomal function. Taken together, our data suggest that MIF serves as a protective factor against side-stream smoke exposure-induced myopathic changes through facilitating mitophagy and autophagolysosome formation.

Secretome-Mediated Interactions with Intestinal Epithelial Cells: A Role for Secretome Components from Lactobacillus rhamnosus R0011 in the Attenuation of Salmonella enterica Serovar Typhimurium Secretome and TNF-α-Induced Proinflammatory Responses

Recent evidence suggests that lactic acid bacteria communicate with host cells via secretome components to influence immune responses but less is known about gut-pathogen secretomes, impact of lactic acid bacteria secretomes on host-pathogen interactions, and the mechanisms underlying these interactions. Genome-wide microarrays and cytokine profiling were used to interrogate the impact of the Lactobacillus rhamnosus R0011 secretome (LrS) on TNF-α and Salmonella enterica subsp. enterica serovar Typhimurium secretome (STS)-induced outcomes in human intestinal epithelial cells. The LrS attenuated both TNF-α- and STS-induced gene expression involved in NF-κB and MAPK activation, as well as expression of genes involved in other immune-related signaling pathways. Specifically, the LrS induced the expression of dual specificity phosphatase 1 (DUSP1), activating transcription factor 3 (ATF3), and tribbles pseudokinase 3 (TRIB3), negative regulators of innate immune signaling, in HT-29 intestinal epithelial cells challenged with TNF-α or STS. TNF-α- and STS-induced acetylation of H3 and H4 histones was attenuated by the LrS, as was the production of TNF-α- and STS-induced proinflammatory cytokines and chemokines. Interestingly, the LrS induced production of macrophage migration inhibitory factor (MIF), a cytokine involved in host-microbe interactions at the gut interface. We propose that the LrS attenuates proinflammatory mediator expression through increased transcription of negative regulators of innate immune activity and changes in global H3 and H4 histone acetylation. To our knowledge, these findings provide novel insights into the complex multifaceted mechanisms of action behind secretome-mediated interdomain communication at the gut-mucosal interface.

The role of MIF in chronic lung diseases: looking beyond inflammation

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that has been associated with many diseases. Most studies found in literature describe MIF as a proinflammatory cytokine involved in chronic inflammatory conditions, but evidence from last years suggests that many of its key effects are not directly related to inflammation. In fact, MIF is constitutively expressed in most human tissues and in some cases in high levels, which does not reflect the pattern of expression of a classic proinflammatory cytokine. Moreover, MIF is highly expressed during embryonic development and decreases during adulthood, which point toward a more likely role as growth factor. Accordingly, MIF knockout mice develop age-related spontaneous emphysema, suggesting that MIF presence (e.g., in younger individuals and wild-type animals) is part of a healthy lung. In view of this new line of evidence, we aimed to review data on the role of MIF in the pathogenesis of chronic lung diseases.

Targeting Parasite-Produced Macrophage Migration Inhibitory Factor as an Antivirulence Strategy With Antibiotic-Antibody Combination to Reduce Tissue Damage

Targeting virulence factors represents a promising alternative approach to antimicrobial therapy, through the inhibition of pathogenic pathways that result in host tissue damage. Yet, virulence inhibition remains an understudied area in parasitology. Several medically important protozoan parasites such as Plasmodium, Entamoeba, Toxoplasma, and Leishmania secrete an inflammatory macrophage migration inhibitory factor (MIF) cytokine homolog, a virulence factor linked to severe disease. The aim of this study was to investigate the effectiveness of targeting parasite-produced MIF as combination therapy with standard antibiotics to reduce disease severity. Here, we used Entamoeba histolytica as the model MIF-secreting protozoan, and a mouse model that mirrors severe human infection. We found that intestinal inflammation and tissue damage were significantly reduced in mice treated with metronidazole when combined with anti-E. histolytica MIF antibodies, compared to metronidazole alone. Thus, this preclinical study provides proof-of-concept that combining antiparasite MIF-blocking antibodies with current standard-of-care antibiotics might improve outcomes in severe protozoan infections.

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.