Role of macrophage migration inhibitory factor in heat-induced apoptosis in keratinocytes

Fever-range whole body hyperthermia leads to changes in immune-related genes and miRNA machinery in Wistar rats

OBJECTIVE

Fever is defined as a rise in body temperature upon disease. Fever-range hyperthermia (FRH) is a simplified model of fever and a well-established medical procedure. Despite its beneficial effects, the molecular changes induced by FRH remain poorly characterized. The aim of this study was to investigate the influence of FRH on regulatory molecules such as cytokines and miRNAs involved in inflammatory processes.

METHODS

We developed a novel, fast rat model of infrared-induced FRH. The body temperature of animals was monitored using biotelemetry. FRH was induced by the infrared lamp and heating pad. White blood cell counts were monitored using Auto Hematology Analyzer. In peripheral blood mononuclear cells, spleen and liver expression of immune-related genes (IL-10, MIF and G-CSF, IFN-γ) and miRNA machinery (DICER1, TARBP2) was analyzed with RT-qPCR. Furthermore, RT-qPCR was used to explore miRNA-155 levels in the plasma of rats.

RESULTS

We observed a decrease in the total number of leukocytes due to lower number of lymphocytes, and an increase in the number of granulocytes. Furthermore, we observed elevated expressions of DICER1, TARBP2 and granulocyte colony-stimulating factor (G-CSF) in the spleen, liver and PBMCs immediately following FRH. FRH treatment also had anti-inflammatory effects, evidenced by the downregulation of pro-inflammatory macrophage migration inhibitor factor (MIF) and miR-155, and the increased expression of anti-inflammatory IL-10.

CONCLUSION

FRH affects the expression of molecules involved in inflammatory processes leading to alleviated inflammation. We suppose these effects may be miRNAs-dependent and FRH can be involved in therapies where anti-inflammatory action is needed.

Macrophage migration inhibitory factor protects bone marrow mesenchymal stem cells from hypoxia/ischemia-induced apoptosis by regulating lncRNA MEG3

OBJECTIVES

This research was performed to explore the effect of macrophage migration inhibitory factor (MIF) on the apoptosis of bone marrow mesenchymal stem cells (BMSCs) in ischemia and hypoxia environments.

METHODS

The cell viability of BMSCs incubated under hypoxia/ischemia (H/I) conditions with or without pretreatment with MIF or triglycidyl isocyanurate (TGIC) was detected using cell counting kit-8 (CCK-8) analysis. Plasmids containing long noncoding RNA (lncRNA) maternally expressed gene 3 (MEG3) or β-catenin small interfering RNA (siRNA) were used to overexpress or downregulate the corresponding gene, and the p53 signaling pathway was activated by pretreatment with TGIC. The influences of MIF, overexpression of lncRNA MEG3, activation of the p53 signaling pathway, and silencing of β-catenin on H/I-induced apoptosis of BMSCs were revealed by western blotting, flow cytometry, and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) staining.

RESULTS

From the results of CCK-8 assay, western blotting, and flow cytometry, pretreatment with MIF significantly decreased the H/I-induced apoptosis of BMSCs. This effect was inhibited when lncRNA MEG3 was overexpressed by plasmids containing MEG3. The p53 signaling pathway was activated by TGIC, and β-catenin was silenced by siRNA. From western blot results, the expression levels of β-catenin in the nucleus and phosphorylated p53 (p-p53) were downregulated and upregulated, respectively, when the lncRNA MEG3 was overexpressed. Through flow cytometry, MIF was also shown to significantly alleviate the increased reactive oxygen species (ROS) level of BMSCs caused by H/I.

CONCLUSIONS

In summary, we conclude that MIF protected BMSCs from H/I-induced apoptosis by downregulating the lncRNA MEG3/p53 signaling pathway, activating the Wnt/β-catenin signaling pathway, and decreasing ROS levels.

Expression of macrophage migration inhibitory factor and its receptor CD74 in systemic sclerosis

Macrophage migration inhibitory factor (MIF) has been associated with the pathogenesis of several rheumatic diseases. In systemic sclerosis (SSc) it has been shown that MIF expression is dysregulated in serum and skin. However, the MIF receptor, CD74, has been poorly investigated and its potential role in the pathogenesis of SSc remains unknown. This study aimed to analyze mRNA, tissue, and serum expression of MIF and CD74 in patients with limited (lcSSc) and diffuse (dcSSc) systemic sclerosis. A case-control study in 20 SSc patients and 20 control subjects (CS) from southern México was conducted. MIF and CD74 mRNA expression levels were quantified by real-time PCR, MIF serum levels were measured by an ELISA kit, and MIF and its receptor CD74 were evaluated by immunohistochemistry of skin biopsies. MIF mRNA expression was significantly higher in CS than in SSc patients (p = 0.02), while CD74 showed no differences between patients and CS. MIF serum levels were similar between SSc patients and CS: dcSSc = 3.82 ng/ml, lcSSc = 3.57 ng/ml, and CS = 3.28 ng/ml. In skin biopsies of SSc, MIF and CD74 were enhanced in keratinocytes, while they showed decreased expression in endothelial cells. On the other hand, the staining of CD74 was high in fibroblasts of dcSSc patients. Our findings show MIF and CD74 deregulation at the transcriptional and translational levels in SSc, which might be associated with the proinflammatory process leading to tissue remodeling and excessive fibrosis in SSc.

Macrophage migration inhibitory factor (MIF): A multifaceted cytokine regulated by genetic and physiological strategies

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine encoded within a functionally polymorphic genetic locus. MIF was initially recognized as a cytokine generated by activated T cells, but in recent days it has been identified as a multipotent key cytokine secreted by many other cell types involved in immune response and physiological processes. MIF is a highly conserved 12.5 kDa secretory protein that is involved in numerous biological processes. The expression and secretion profile of MIF suggests that MIF to be ubiquitously and constitutively expressed in almost all mammalian cells and is vital for numerous physiological processes. MIF is a critical upstream mediator of host innate and adaptive immunity and survival pathways resulting in the clearance of pathogens thus playing a protective role during infectious diseases. On the other hand, MIF being an immune modulator accelerates detrimental inflammation, promotes cancer metastasis and progression, thus worsening disease conditions. Several reports demonstrated that genetic and physiological factors, including MIF gene polymorphisms, posttranslational regulations, and receptor binding control the functional activities of MIF. Taking into consideration the multi-faceted role of MIF both in physiology and pathology, we thought it is timely to review and summarize the expressional and functional regulation of MIF, its functional mechanisms associated with its beneficial and pathological roles, and MIF-targeting therapies. Thus, our review will provide an overview on how MIF is regulated, its response, and the potency of the therapies that target MIF.

Role of the Macrophage Migration Inhibitory Factor (MIF) in the survival of first trimester human placenta under induced stress conditions

Macrophage Migration Inhibitory Factor (MIF) is a multifunctional molecule highly secreted by human placenta mainly in the early phases of pregnancy. Studies in different cells show that MIF is a pro-survival factor by binding to its receptor CD74. By using the in vitro model of placental explants from first trimester pregnancy, we investigated the role of MIF in the survival of placental cells under induced stress conditions that promote apoptosis or mimic the hypoxia/re-oxygenation (H/R) injury that placenta could suffer in vivo. We demonstrated that recombinant MIF (rMIF) treatment was able to reduce caspase-3 activation when cultures were challenged with the apoptosis-inducer Carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP) while, in the cultures exposed to H/R, the treatment with rMIF did not show any effect. However, a significant increase in caspase-3 and caspase-8 activation was found when H/R-exposed cultures, were treated with anti-MIF or anti-CD74 antibody. We also observed that under H/R, a significant amount of endogenous MIF was released into the medium, which could account for the lack of effect of rMIF added to the cultures. Our results demonstrate for the first time that the MIF/CD74 axis contributes to maintain trophoblast homeostasis, by preventing abnormal apoptotic death.

Role of lincRNA‑p21 in the protective effect of macrophage inhibition factor against hypoxia/serum deprivation‑induced apoptosis in mesenchymal stem cells

Stem cell transplantation is a promising clinical strategy for curing ischemic cardiomyopathy. However, its efficacy is impaired by low cell survival following transplantation, partly caused by insufficient resistance of the transplanted stem cells to severe oxidative stress at the injury site. In the current study, it was demonstrated that the small‑molecule macrophage migration inhibitory factor (MIF) enhanced the defense of bone marrow‑derived mesenchymal stem cells (MSCs) against hypoxia/serum deprivation (SD)‑induced apoptosis in vitro. MIF significantly suppressed apoptosis and caspase family activities through inhibition of long intergenic noncoding (linc) RNA‑p21 to maintain activation of the Wnt/β‑catenin signaling pathway. The regulatory loop between MIF and the lincRNA‑p21‑Wnt/β‑catenin signaling pathway was identified to be associated with the inhibition of oxidative stress. The involvement of the lincRNA‑p21‑Wnt/β‑catenin signaling pathway in the effects of MIF in MSCs by overexpression of lincRNA‑p21and silencing β‑catenin using small interfering RNA was also demonstrated, both of which abolished the anti‑apoptotic and anti‑oxidative effects of MIF in MSCs under hypoxia/SD conditions. In conclusion, MIF protected MSCs from hypoxia/SD‑induced apoptosis by interacting with lincRNA‑p21, leading to activation of the downstream Wnt/β‑catenin signaling pathway and decreased oxidative stress. Thus, treatment with MIF may have important therapeutic implications in improving MSC survival and therapeutic efficiency.