Targeting MIF in Cancer: Therapeutic Strategies, Current Developments, and Future Opportunities

The role of macrophage migration inhibitory factor family and CD74 in the pathogenesis of melanoma

Melanoma is an aggressive tumour with poor prognosis that arises from the malignant transformation of melanocytes. Over the past few decades, intense research into the pathogenesis of melanoma has led to the development of BRAF and immune checkpoint inhibitors, including antibodies against programmed cell death protein 1 (PD-1) and cytotoxic T lymphocyte-associated protein 4 (CTLA-4), which have shown clinically significant efficacy. However, some tumours do not respond to these therapies initially or become treatment resistant. Most melanoma tissues appear to possess biological characteristics that allow them to evade these treatments, and identifying these characteristics is one of the major challenges facing cancer researchers. One such characteristic that has recently gained attention is the role of macrophage migration inhibitory factor (MIF) and its receptor CD74. This review outlines the cellular and molecular functions of CD74, MIF and their family of proteins. We then review their roles in tumours based on previous reports, highlight their pathological significance in melanoma and discuss their potential as therapeutic targets.

Understanding the immunosuppressive microenvironment of glioma: mechanistic insights and clinical perspectives

Glioblastoma (GBM), the predominant and primary malignant intracranial tumor, poses a formidable challenge due to its immunosuppressive microenvironment, thereby confounding conventional therapeutic interventions. Despite the established treatment regimen comprising surgical intervention, radiotherapy, temozolomide administration, and the exploration of emerging modalities such as immunotherapy and integration of medicine and engineering technology therapy, the efficacy of these approaches remains constrained, resulting in suboptimal prognostic outcomes. In recent years, intensive scrutiny of the inhibitory and immunosuppressive milieu within GBM has underscored the significance of cellular constituents of the GBM microenvironment and their interactions with malignant cells and neurons. Novel immune and targeted therapy strategies have emerged, offering promising avenues for advancing GBM treatment. One pivotal mechanism orchestrating immunosuppression in GBM involves the aggregation of myeloid-derived suppressor cells (MDSCs), glioma-associated macrophage/microglia (GAM), and regulatory T cells (Tregs). Among these, MDSCs, though constituting a minority (4-8%) of CD45+ cells in GBM, play a central component in fostering immune evasion and propelling tumor progression, angiogenesis, invasion, and metastasis. MDSCs deploy intricate immunosuppressive mechanisms that adapt to the dynamic tumor microenvironment (TME). Understanding the interplay between GBM and MDSCs provides a compelling basis for therapeutic interventions. This review seeks to elucidate the immune regulatory mechanisms inherent in the GBM microenvironment, explore existing therapeutic targets, and consolidate recent insights into MDSC induction and their contribution to GBM immunosuppression. Additionally, the review comprehensively surveys ongoing clinical trials and potential treatment strategies, envisioning a future where targeting MDSCs could reshape the immune landscape of GBM. Through the synergistic integration of immunotherapy with other therapeutic modalities, this approach can establish a multidisciplinary, multi-target paradigm, ultimately improving the prognosis and quality of life in patients with GBM.

Blocking the MIF-CD74 axis augments radiotherapy efficacy for brain metastasis in NSCLC via synergistically promoting microglia M1 polarization

BACKGROUND

Brain metastasis is one of the main causes of recurrence and death in non-small cell lung cancer (NSCLC). Although radiotherapy is the main local therapy for brain metastasis, it is inevitable that some cancer cells become resistant to radiation. Microglia, as macrophages colonized in the brain, play an important role in the tumor microenvironment. Radiotherapy could activate microglia to polarize into both the M1 and M2 phenotypes. Therefore, searching for crosstalk molecules within the microenvironment that can specifically regulate the polarization of microglia is a potential strategy for improving radiation resistance.

METHODS

We used databases to detect the expression of MIF in NSCLC and its relationship with prognosis. We analyzed the effects of targeted blockade of the MIF/CD74 axis on the polarization and function of microglia during radiotherapy using flow cytometry. The mouse model of brain metastasis was used to assess the effect of targeted blockade of MIF/CD74 axis on the growth of brain metastasis.

RESULT

Our findings reveals that the macrophage migration inhibitory factor (MIF) was highly expressed in NSCLC and is associated with the prognosis of NSCLC. Mechanistically, we demonstrated CD74 inhibition reversed radiation-induced AKT phosphorylation in microglia and promoted the M1 polarization in combination of radiation. Additionally, blocking the MIF-CD74 interaction between NSCLC and microglia promoted microglia M1 polarization. Furthermore, radiation improved tumor hypoxia to decrease HIF-1α dependent MIF secretion by NSCLC. MIF inhibition enhanced radiosensitivity for brain metastasis via synergistically promoting microglia M1 polarization in vivo.

CONCLUSIONS

Our study revealed that targeting the MIF-CD74 axis promoted microglia M1 polarization and synergized with radiotherapy for brain metastasis in NSCLC.

Coupled scRNA-seq and Bulk-seq reveal the role of HMMR in hepatocellular carcinoma

Background

Hyaluronan-mediated motility receptor (HMMR) is overexpressed in multiple carcinomas and influences the development and treatment of several cancers. However, its role in hepatocellular carcinoma (HCC) remains unclear.

Methods

The "limma" and "GSVA" packages in R were used to perform differential expression analysis and to assess the activity of signalling pathways, respectively. InferCNV was used to infer copy number variation (CNV) for each hepatocyte and "CellChat" was used to analyse intercellular communication networks. Recursive partitioning analysis (RPA) was used to re-stage HCC patients. The IC50 values of various drugs were evaluated using the "pRRophetic" package. In addition, quantitative reverse transcription polymerase chain reaction (qRT-PCR) was performed to confirm HMMR expression in an HCC tissue microarray. Flow cytometry (FCM) and cloning, Edu and wound healing assays were used to explore the capacity of HMMR to regulate HCC tumour.

Results

Multiple cohort studies and qRT-PCR demonstrated that HMMR was overexpressed in HCC tissue compared with normal tissue. In addition, HMMR had excellent diagnostic performance. HMMR knockdown inhibited the proliferation and migration of HCC cells in vitro. Moreover, high HMMR expression was associated with "G2M checkpoint" and "E2F targets" in bulk RNA and scRNA-seq, and FCM confirmed that HMMR could regulate the cell cycle. In addition, HMMR was involved in the regulation of the tumour immune microenvironment via immune cell infiltration and intercellular interactions. Furthermore, HMMR was positively associated with genomic heterogeneity with patients with high HMMR expression potentially benefitting more from immunotherapy. Moreover, HMMR was associated with poor prognosis in patients with HCC and the re-staging by recursive partitioning analysis (RPA) gave a good prognosis prediction value and could guide chemotherapy and targeted therapy.

Conclusion

The results of the present study show that HMMR could play a role in the diagnosis, prognosis, and treatments of patients with HCC based on bulk RNA-seq and scRAN-seq analyses and is a promising molecular marker for HCC.

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

OBJECTIVE

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

RESULTS

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

CONCLUSION

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

Lactic acid in macrophage polarization: A factor in carcinogenesis and a promising target for cancer therapy

Cancer remains a formidable challenge, continually revealing its intricate nature and demanding novel treatment approaches. Within this intricate landscape, the tumor microenvironment and its dynamic components have gained prominence, particularly macrophages that can adopt diverse polarization states, exerting a profound influence on cancer progression. Recent revelations have spotlighted lactic acid as a pivotal player in this complex interplay. This review systematically explores lactic acid's multifaceted role in macrophage polarization, focusing on its implications in carcinogenesis. We commence by cultivating a comprehensive understanding of the tumor microenvironment and the pivotal roles played by macrophages. The dynamic landscape of macrophage polarization, typified by M1 and M2 phenotypes, is dissected to reveal its substantial impact on tumor progression. Lactic acid, a metabolic byproduct, emerges as a key protagonist, and we meticulously unravel the mechanisms underpinning its generation within cancer cells, shedding light on its intimate association with glycolysis and its transformative effects on the tumor microenvironment. Furthermore, we decipher the intricate molecular framework that underlies lactic acid's pivotal role in facilitating macrophage polarization. Our review underscores lactic acid's dual role in carcinogenesis, orchestrating tumor growth and immune modulation within the tumor microenvironment, thereby profoundly influencing the balance between pro-tumor and anti-tumor immune responses. This duality highlights the therapeutic potential of selectively manipulating lactic acid metabolism for cancer treatment. Exploring strategies to inhibit lactic acid production by tumor cells, novel approaches to impede lactic acid transport in the tumor microenvironment, and the burgeoning field of immunotherapeutic cancer therapies utilizing lactic acid-induced macrophage polarization form the core of our investigation.

Ibudilast Protects Retinal Bipolar Cells from Excitotoxic Retinal Damage and Activates the mTOR Pathway

Ibudilast, an inhibitor of macrophage migration inhibitory factor (MIF) and phosphodiesterase (PDE), has been recently shown to have neuroprotective effects in a variety of neurologic diseases. We utilize a chick excitotoxic retinal damage model to investigate ibudilast's potential to protect retinal neurons. Using single cell RNA-sequencing (scRNA-seq), we find that MIF, putative MIF receptors CD74 and CD44, and several PDEs are upregulated in different retinal cells during damage. Intravitreal ibudilast is well tolerated in the eye and causes no evidence of toxicity. Ibudilast effectively protects neurons in the inner nuclear layer from NMDA-induced cell death, restores retinal layer thickness on spectral domain optical coherence tomography, and preserves retinal neuron function, particularly for the ON bipolar cells, as assessed by electroretinography. PDE inhibition seems essential for ibudilast's neuroprotection, as AV1013, the analogue that lacks PDE inhibitor activity, is ineffective. scRNA-seq analysis reveals upregulation of multiple signaling pathways, including mTOR, in damaged Müller glia (MG) with ibudilast treatment compared to AV1013. Components of mTORC1 and mTORC2 are upregulated in both bipolar cells and MG with ibudilast. The mTOR inhibitor rapamycin blocked accumulation of pS6 but did not reduce TUNEL positive dying cells. Additionally, through ligand-receptor interaction analysis, crosstalk between bipolar cells and MG may be important for neuroprotection. We have identified several paracrine signaling pathways that are known to contribute to cell survival and neuroprotection and might play essential roles in ibudilast function. These findings highlight ibudilast's potential to protect inner retinal neurons during damage and show promise for future clinical translation.

Differential cytokine and chemokine expression after ablation vs. resection in colorectal cancer liver metastasis

Background

Surgical resection remains the main curative treatment for colorectal liver metastases (CRLM). Radiofrequency ablation (RFA) is increasingly employed for small, deep lying or otherwise inoperable lesions. However, RFA can induce pro-tumorigenic effects on residual tumor cells, hereby possibly promoting tumor recurrence. Contrastingly, post-RFA tumor debris as an antigen source can also generate anti-cancer immune responses. Utilizing this, current studies on combining RFA with immune therapy appear promising. Here, in an attempt to shed light on this controversy, cytokines involved in inflammation, (lymph)angiogenesis, immune cell recruitment and tumor cell invasion were investigated post-RFA versus post-resection in CRLM patients.

Methods

Cytokine and chemokine serum levels pre-operation, 4 h and 24 h post-operation were analyzed in CRLM patients undergoing RFA (n = 8) or partial hepatectomy (n = 9) using Multiplex immunoassays. Statistical analyses were performed between as well as within individual intervention groups.

Results

Post-RFA, significantly increased levels of acute phase proteins SAA1 and S100A8, IL-6, IL-1Ra, MIP3b (CCL19) and MMP9 were observed along with decreases in Fibronectin, MCP-1 (CCL2), and Tie-2. Post-resection, increased levels of PDGFbb, I309 (CCL1), Apelin, MIF, IL-1b and TNFα were seen. All p-values <0.05.

Conclusion

Pro-inflammatory responses mediated by different cytokines were seen after both RFA and resection, possibly influencing residual tumor cells and tumor recurrence. As both ablation and resection trigger inflammation and immune cell recruitment (albeit via distinct mechanisms), these data suggest that further research may explore combining immune therapy with not only RFA but also resection.

Key message

Analysis of patients' serum after radiofrequency ablation versus resection of colorectal liver metastases (CRLM) showed that these interventions trigger inflammation and immune cell recruitment, via different cyto- and chemokine pathways. This suggests a possible future strategy of combining immune therapy with not only ablative techniques but also with resection of CRLM.

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

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

Association between circulating inflammatory markers and adult cancer risk: a Mendelian randomization analysis

BACKGROUND

Tumour-promoting inflammation is a "hallmark" of cancer and conventional epidemiological studies have reported links between various inflammatory markers and cancer risk. The causal nature of these relationships and, thus, the suitability of these markers as intervention targets for cancer prevention is unclear.

METHODS

We meta-analysed 6 genome-wide association studies of circulating inflammatory markers comprising 59,969 participants of European ancestry. We then used combined cis-Mendelian randomization and colocalisation analysis to evaluate the causal role of 66 circulating inflammatory markers in risk of 30 adult cancers in 338,294 cancer cases and up to 1,238,345 controls. Genetic instruments for inflammatory markers were constructed using genome-wide significant (P < 5.0 × 10-8) cis-acting SNPs (i.e., in or ±250 kb from the gene encoding the relevant protein) in weak linkage disequilibrium (LD, r2 < 0.10). Effect estimates were generated using inverse-variance weighted random-effects models and standard errors were inflated to account for weak LD between variants with reference to the 1000 Genomes Phase 3 CEU panel. A false discovery rate (FDR)-corrected P-value ("q-value") <0.05 was used as a threshold to define "strong evidence" to support associations and 0.05 ≤ q-value < 0.20 to define "suggestive evidence". A colocalisation posterior probability (PPH4) >70% was employed to indicate support for shared causal variants across inflammatory markers and cancer outcomes. Findings were replicated in the FinnGen study and then pooled using meta-analysis.

FINDINGS

We found strong evidence to support an association of genetically-proxied circulating pro-adrenomedullin concentrations with increased breast cancer risk (OR: 1.19, 95% CI: 1.10-1.29, q-value = 0.033, PPH4 = 84.3%) and suggestive evidence to support associations of interleukin-23 receptor concentrations with increased pancreatic cancer risk (OR: 1.42, 95% CI: 1.20-1.69, q-value = 0.055, PPH4 = 73.9%), prothrombin concentrations with decreased basal cell carcinoma risk (OR: 0.66, 95% CI: 0.53-0.81, q-value = 0.067, PPH4 = 81.8%), and interleukin-1 receptor-like 1 concentrations with decreased triple-negative breast cancer risk (OR: 0.92, 95% CI: 0.88-0.97, q-value = 0.15, PPH4 = 85.6%). These findings were replicated in pooled analyses with the FinnGen study. Though suggestive evidence was found to support an association of macrophage migration inhibitory factor concentrations with increased bladder cancer risk (OR: 2.46, 95% CI: 1.48-4.10, q-value = 0.072, PPH4 = 76.1%), this finding was not replicated when pooled with the FinnGen study. For 22 of 30 cancer outcomes examined, there was little evidence (q-value ≥0.20) that any of the 66 circulating inflammatory markers examined were associated with cancer risk.

INTERPRETATION

Our comprehensive joint Mendelian randomization and colocalisation analysis of the role of circulating inflammatory markers in cancer risk identified potential roles for 4 circulating inflammatory markers in risk of 4 site-specific cancers. Contrary to reports from some prior conventional epidemiological studies, we found little evidence of association of circulating inflammatory markers with the majority of site-specific cancers evaluated.

FUNDING

Cancer Research UK (C68933/A28534, C18281/A29019, PPRCPJT∖100005), World Cancer Research Fund (IIG_FULL_2020_022), National Institute for Health Research (NIHR202411, BRC-1215-20011), Medical Research Council (MC_UU_00011/1, MC_UU_00011/3, MC_UU_00011/6, and MC_UU_00011/4), Academy of Finland Project 326291, European Union's Horizon 2020 grant agreement no. 848158 (EarlyCause), French National Cancer Institute (INCa SHSESP20, 2020-076), Versus Arthritis (21173, 21754, 21755), National Institutes of Health (U19 CA203654), National Cancer Institute (U19CA203654).

MIF contribution to progressive brain diseases

Progressive brain diseases create a huge social and economic burden on modern societies as a major cause of disability and death. Incidence of brain diseases has a significantly increasing trend and merits new therapeutic strategies. At the base of many progressive brain malfunctions is a process of unresolved, chronic inflammation. Macrophage migration inhibitory factor, MIF, is an inflammatory mediator that recently gained interest of neuro-researchers due to its varied effects on the CNS such as participation of nervous system development, neuroendocrine functions, and modulation of neuroinflammation. MIF appears to be a candidate as a new biomarker and target of novel therapeutics against numerous neurologic diseases ranging from cancer, autoimmune diseases, vascular diseases, neurodegenerative pathology to psychiatric disorders. In this review, we will focus on MIF's crucial role in neurological diseases such as multiple sclerosis (MS), Alzheimer's disease (AD) and glioblastoma (GBM).

Temporal genomic analysis of melanoma rejection identifies regulators of tumor immune evasion

Decreased intra-tumor heterogeneity (ITH) correlates with increased patient survival and immunotherapy response. However, even highly homogenous tumors may display variability in their aggressiveness, and how immunologic-factors impinge on their aggressiveness remains understudied. Here we studied the mechanisms responsible for the immune-escape of murine tumors with low ITH. We compared the temporal growth of homogeneous, genetically-similar single-cell clones that are rejected vs. those that are not-rejected after transplantation in-vivo using single-cell RNA sequencing and immunophenotyping. Non-rejected clones showed high infiltration of tumor-associated-macrophages (TAMs), lower T-cell infiltration, and increased T-cell exhaustion compared to rejected clones. Comparative analysis of rejection-associated gene expression programs, combined with in-vivo CRISPR knockout screens of candidate mediators, identified Mif (macrophage migration inhibitory factor) as a regulator of immune rejection. Mif knockout led to smaller tumors and reversed non-rejection-associated immune composition, particularly, leading to the reduction of immunosuppressive macrophage infiltration. Finally, we validated these results in melanoma patient data.

Decoding meningioma heterogeneity and neoplastic cell-macrophage interaction through single-cell transcriptome profiling across pathological grades

BACKGROUND

Analyzing meningioma of distinct pathological types at the single-cell level can provide new and valuable insights into the specific biological mechanisms of each cellular subpopulation, as well as their vital interplay within the tumor microenvironment.

METHODS

We recruited patients diagnosed with four distinct types of meningioma and performed single-cell RNA sequencing on their tumor samples, concurrently analyzing a publicly available dataset for comparison. Next, we separated the cells into discrete clusters and identified their unique identities. Using pseudotime analysis, we demonstrated cellular differentiation and dynamics. To investigate biological function, we employed weighted gene co-expression network analysis, gene regulatory network, and gene set enrichment analysis. Additionally, we conducted cell-cell communication analyses to characterize interactions among different clusters and validated a crucial interaction using multiple immunofluorescence staining.

RESULTS

The single-cell transcriptomic profiles for five meningioma of different pathological types demonstrated that neoplastic cells exhibited high inter-sample heterogeneity and diverse biological functions featured by metabolic regulation. A small cluster of neoplastic cells (N5 cluster, < 3%) was most proliferative, indicated by high expression of MKI67 and TOP2A. They were primarily observed in our atypical and transitional meningioma samples and located at the beginning of the pseudotime differentiation branch for neoplastic cells. Macrophages, the most abundant immune cells present, showed two distinct developmental trajectories, one promoting and the other suppressing meningioma growth, with the MIF-CD74 interaction serving as the primary signaling pathway for MIF signals in the tumor environment. Unexpectedly, despite its small cluster size, the N5 cluster demonstrated a significant contribution in this interaction. By staining pathological sections of more samples, we found that this interaction was widely present in different types of meningiomas.

CONCLUSIONS

Meningioma neoplastic cells' diverse types cause inter-sample heterogeneity and a wide range of functions. Some proliferative neoplastic cell may educate macrophages, which promotes tumorigenesis possibly through the MIF-CD74 interaction. It provides novel clues for future potential therapeutic avenues.

MIF promotes Th17 cell differentiation in Hashimoto's thyroiditis by binding HVEM and activating NF-κB signaling pathway

Hashimoto's thyroiditis is a typical thyroid autoimmune disease and Th17 cells are crucial in its development. In recent years, MIF (Macrophage Migration Inhibitory Factor) has been found to promote the secretion of IL-17A and the production and differentiation of Th17 cells. However, the specific mechanism of it remains unclear. Here, we found that the expression of MIF, IL-17A and HVEM (Herpes Virus Entry Mediator) were up-regulated in HT patients. The proportion of Th17 cells in peripheral blood mononuclear cells was positively correlated with the serum MIF protein level. We further found that the expression of HVEM and the phosphorylation level of NF-κB in peripheral blood mononuclear cells of HT patients were significantly increased. Therefore, we speculated that MIF promotes Th17 cell differentiation through HVEM and NF-κB signaling pathways. Further mechanism studies showed that MIF could directly bind to HVEM, and the stimulation of rhMIF in vitro could increase the expression of HVEM and activate NF-κB signaling pathways to promote Th17 cell differentiation. After blocking HVEM with HVEM antibody, the effect of MIF on Th17 cell differentiation disappeared. The results above show that the differentiation of Th17 cells is promoted by MIF combined with HVEM through NF-κB signaling pathways. Our research provides a new theory to the regulation mechanism of Th17 cell differentiation and gives hint to new potential therapeutic targets for HT.

Macrophage migration inhibitory factor (MIF) and its homolog D-dopachrome tautomerase (D-DT) are significant promotors of UVB- but not chemically induced non-melanoma skin cancer

Non-melanoma skin cancer (NMSC) is the most common cancer in Caucasians worldwide. We investigated the pathophysiological role of MIF and its homolog D-DT in UVB- and chemically induced NMSC using Mif-/-, D-dt-/- and Mif-/-/D-dt-/- mice on a hairless SKH1 background. Knockout of both cytokines showed similar attenuating effects on inflammation after acute UVB irradiation and tumor formation during chronic UVB irradiation, without additive protective effects noted in double knockout mice, indicating that both cytokines activate a similar signaling threshold. In contrast, genetic deletion of Mif and D-dt had no major effects on chemically induced skin tumors. To get insight into the contributing mechanisms, we used an in vitro 3D skin model with incorporated macrophages. Application of recombinant MIF and D-DT led to an accumulation of macrophages within the epidermal part that could be reversed by selective inhibitors of MIF and D-DT pathways. In summary, our data indicate that MIF and D-DT contribute to the development and progression of UVB- but not chemically induced NMSC, a role at least partially accounted by effects of both cytokines on epidermal macrophage accumulation. These data highlight that MIF and D-DT are both potential therapeutic targets for the prevention of photocarcinogenesis but not chemical carcinogenesis.

Association between circulating inflammatory markers and adult cancer risk: a Mendelian randomization analysis

Background

Tumour-promoting inflammation is a "hallmark" of cancer and conventional epidemiological studies have reported links between various inflammatory markers and cancer risk. The causal nature of these relationships and, thus, the suitability of these markers as intervention targets for cancer prevention is unclear.

Methods

We meta-analysed 6 genome-wide association studies of circulating inflammatory markers comprising 59,969 participants of European ancestry. We then used combined cis-Mendelian randomization and colocalisation analysis to evaluate the causal role of 66 circulating inflammatory markers in risk of 30 adult cancers in 338,162 cancer cases and up to 824,556 controls. Genetic instruments for inflammatory markers were constructed using genome-wide significant (P < 5.0 x 10-8) cis-acting SNPs (i.e. in or ±250 kb from the gene encoding the relevant protein) in weak linkage disequilibrium (LD, r2 < 0.10). Effect estimates were generated using inverse-variance weighted random-effects models and standard errors were inflated to account for weak LD between variants with reference to the 1000 Genomes Phase 3 CEU panel. A false discovery rate (FDR)-corrected P-value ("q-value") < 0.05 was used as a threshold to define "strong evidence" to support associations and 0.05 ≤ q-value < 0.20 to define "suggestive evidence". A colocalisation posterior probability (PPH4) > 70% was employed to indicate support for shared causal variants across inflammatory markers and cancer outcomes.

Results

We found strong evidence to support an association of genetically-proxied circulating pro-adrenomedullin concentrations with increased breast cancer risk (OR 1.19, 95% CI 1.10-1.29, q-value=0.033, PPH4=84.3%) and suggestive evidence to support associations of interleukin-23 receptor concentrations with increased pancreatic cancer risk (OR 1.42, 95% CI 1.20-1.69, q-value=0.055, PPH4=73.9%), prothrombin concentrations with decreased basal cell carcinoma risk (OR 0.66, 95% CI 0.53-0.81, q-value=0.067, PPH4=81.8%), macrophage migration inhibitory factor concentrations with increased bladder cancer risk (OR 1.14, 95% CI 1.05-1.23, q-value=0.072, PPH4=76.1%), and interleukin-1 receptor-like 1 concentrations with decreased triple-negative breast cancer risk (OR 0.92, 95% CI 0.88-0.97, q-value=0.15), PPH4=85.6%). For 22 of 30 cancer outcomes examined, there was little evidence (q-value ≥ 0.20) that any of the 66 circulating inflammatory markers examined were associated with cancer risk.

Conclusion

Our comprehensive joint Mendelian randomization and colocalisation analysis of the role of circulating inflammatory markers in cancer risk identified potential roles for 5 circulating inflammatory markers in risk of 5 site-specific cancers. Contrary to reports from some prior conventional epidemiological studies, we found little evidence of association of circulating inflammatory markers with the majority of site-specific cancers evaluated.

A transcriptomic pan-cancer signature for survival prognostication and prediction of immunotherapy response based on endothelial senescence

BACKGROUND

The microvascular endothelium inherently controls nutrient delivery, oxygen supply, and immune surveillance of malignant tumors, thus representing both biological prerequisite and therapeutic vulnerability in cancer. Recently, cellular senescence emerged as a fundamental characteristic of solid malignancies. In particular, tumor endothelial cells have been reported to acquire a senescence-associated secretory phenotype, which is characterized by a pro-inflammatory transcriptional program, eventually promoting tumor growth and formation of distant metastases. We therefore hypothesize that senescence of tumor endothelial cells (TEC) represents a promising target for survival prognostication and prediction of immunotherapy efficacy in precision oncology.

METHODS

Published single-cell RNA sequencing datasets of different cancer entities were analyzed for cell-specific senescence, before generating a pan-cancer endothelial senescence-related transcriptomic signature termed EC.SENESCENCE.SIG. Utilizing this signature, machine learning algorithms were employed to construct survival prognostication and immunotherapy response prediction models. Machine learning-based feature selection algorithms were applied to select key genes as prognostic biomarkers.

RESULTS

Our analyses in published transcriptomic datasets indicate that in a variety of cancers, endothelial cells exhibit the highest cellular senescence as compared to tumor cells or other cells in the vascular compartment of malignant tumors. Based on these findings, we developed a TEC-associated, senescence-related transcriptomic signature (EC.SENESCENCE.SIG) that positively correlates with pro-tumorigenic signaling, tumor-promoting dysbalance of immune cell responses, and impaired patient survival across multiple cancer entities. Combining clinical patient data with a risk score computed from EC.SENESCENCE.SIG, a nomogram model was constructed that enhanced the accuracy of clinical survival prognostication. Towards clinical application, we identified three genes as pan-cancer biomarkers for survival probability estimation. As therapeutic perspective, a machine learning model constructed on EC.SENESCENCE.SIG provided superior pan-cancer prediction for immunotherapy response than previously published transcriptomic models.

CONCLUSIONS

We here established a pan-cancer transcriptomic signature for survival prognostication and prediction of immunotherapy response based on endothelial senescence.

MAPK4 silencing in gastric cancer drives liver metastasis by positive feedback between cancer cells and macrophages

Liver metastasis is a major cause of death in gastric cancer patients, but the underlying mechanisms are poorly understood. Through a combination of in vivo screening and transcriptome profiling followed by quantitative RT-PCR and tissue array analyses, we found that mitogen-activated protein kinase 4 (MAPK4) downregulation in gastric cancer tissues from patients is significantly associated with liver metastasis and poor prognosis. The knockdown of MAPK4 in gastric cancer cells promotes liver metastasis in orthotopic mouse models. MAPK4 depletion in gastric cancer cells induces the secretion of macrophage migration inhibitory factor (MIF) to polarize tumor-associated macrophages (TAMs) in orthotopic xenograft tumors. Moreover, TAMs activate epithelial-mesenchymal transition of gastric cancer cells to suppress MAPK4 expression, which further increases MIF secretion to polarize TAMs. Taken together, our results suggest a previously undescribed positive feedback loop between cancer cells and macrophages mediated by MAPK4 silencing that facilitates gastric cancer liver metastasis.

MIF promotes cell invasion by the LRP1-uPAR interaction in pancreatic cancer cells

Introduction

Pancreatic ductal adenocarcinoma (PDAC) is characterized by high aggressiveness and a hypoxic tumour microenvironment. Macrophage migration inhibitory factor (MIF) is a hypoxia-related pleiotropic cytokine that plays important roles in cancer. However, its role in PDAC progression has not been fully elucidated.

Methods

The clinical significance of MIF and hypoxia inducible factor 1 subunit alpha (HIF1A) in PDAC was analysed using immunohistochemical staining on PDAC tissues and data from KM-Plotter database. Spatial distribution of MIF and HIF1A gene expression was visualized by spatial transcriptomics in PDAC cell xenografts. To monitor the role of MIF in PDAC cell malignancy, immunostaining, lentivirus shRNA, migration assays, flow cytometry, transcriptomics and in vivo tumorigenicity were performed.

Results

The spatial distribution of MIF and HIF1A was highly correlated and that high MIF expression was associated with poor prognosis of PDAC patients. MIF knockdown impaired cell invasion, with a decrease in the expression of urokinase-type plasminogen activator receptor (uPAR). Although PLAUR transcript was not reduced, a uPAR endocytic receptor, low-density lipoprotein receptor-related protein 1 (LRP1), was upregulated at both the mRNA and protein levels after MIF knockdown. The LRP1 antagonist RAP restored uPAR expression and invasiveness. MIF attenuated the nuclear translocation of p53, a transcriptional regulator of LRP1. Furthermore, MIF downregulation blunted the growth of PDAC cell xenografts and inhibited cell proliferation under normoxia and hypoxia. Transcriptome analysis also provided evidence for the role of MIF in cancer-associated pathways.

Discussion

We demonstrate a novel link between the two pro-invasive agents MIF and uPAR and explain how MIF increases PDAC cell invasion capability. This finding provides a basis for therapeutic intervention of MIF in PDAC progression.

Targeted therapies and checkpoint inhibitors in sarcoma

Sarcomas are defined as a group of mesenchymal malignancies with over 100 heterogeneous subtypes. As a rare and difficult to diagnose entity, micrometastasis is already present at the time of diagnosis in many cases. Current treatment practice of sarcomas consists mainly of surgery, (neo)adjuvant chemo- and/or radiotherapy. Although the past decade has shown that particular genetic abnormalities can promote the development of sarcomas, such as translocations, gain-of-function mutations, amplifications or tumor suppressor gene losses, these insights have not led to established alternative treatment strategies so far. Novel therapeutic concepts with immunotherapy at its forefront have experienced some remarkable success in different solid tumors while their impact in sarcoma remains limited. In this review, the most common immunotherapy strategies in sarcomas, such as immune checkpoint inhibitors, targeted therapy and cytokine therapy are concisely discussed. The programmed cell death (PD)-1/PD-1L axis and apoptosis-inducing cytokines, such as TNF-related apoptosis-inducing ligand (TRAIL), have not yielded the same success like in other solid tumors. However, in certain sarcoma subtypes, e.g. liposarcoma or undifferentiated pleomorphic sarcoma, encouraging results in some cases when employing immune checkpoint inhibitors in combination with other treatment options were found. Moreover, newer strategies such as the targeted therapy against the ancient cytokine macrophage migration inhibitory factor (MIF) may represent an interesting approach worth investigation in the future.

Bone Marrow Macrophages Induce Inflammation by Efferocytosis of Apoptotic Prostate Cancer Cells via HIF-1α Stabilization

The clearance of apoptotic cancer cells by macrophages, known as efferocytosis, fuels the bone-metastatic growth of prostate cancer cells via pro-inflammatory and immunosuppressive processes. However, the exact molecular mechanisms remain unclear. In this study, single-cell transcriptomics of bone marrow (BM) macrophages undergoing efferocytosis of apoptotic prostate cancer cells revealed a significant enrichment in their cellular response to hypoxia. Here, we show that BM macrophage efferocytosis increased hypoxia inducible factor-1alpha (HIF-1α) and STAT3 phosphorylation (p-STAT3 at Tyr705) under normoxic conditions, while inhibitors of p-STAT3 reduced HIF-1α. Efferocytosis promoted HIF-1α stabilization, reduced its ubiquitination, and induced HIF-1α and p-STAT3 nuclear translocation. HIF-1α stabilization in efferocytic BM macrophages resulted in enhanced expression of pro-inflammatory cytokine MIF, whereas BM macrophages with inactive HIF-1α reduced MIF expression upon efferocytosis. Stabilization of HIF-1α using the HIF-prolyl-hydroxylase inhibitor, Roxadustat, enhanced MIF expression in BM macrophages. Furthermore, BM macrophages treated with recombinant MIF protein activated NF-κB (p65) signaling and increased the expression of pro-inflammatory cytokines. Altogether, these findings suggest that the clearance of apoptotic cancer cells by BM macrophages triggers p-STAT3/HIF-1α/MIF signaling to promote further inflammation in the bone tumor microenvironment where a significant number of apoptotic cancer cells are present.

D-dopachrome tautomerase in cardiovascular and inflammatory diseases-A new kid on the block or just another MIF?

Macrophage migration inhibitory factor (MIF) as well as its more recently described structural homolog D-dopachrome tautomerase (D-DT), now also termed MIF-2, are atypical cytokines and chemokines with key roles in host immunity. They also have an important pathogenic role in acute and chronic inflammatory conditions, cardiovascular diseases, lung diseases, adipose tissue inflammation, and cancer. Although our mechanistic understanding of MIF-2 is relatively limited compared to the extensive body of evidence available for MIF, emerging data suggests that MIF-2 is not only a functional phenocopy of MIF, but may have differential or even oppositional activities, depending on the disease and context. In this review, we summarize and discuss the similarities and differences between MIF and MIF-2, with a focus on their structures, receptors, signaling pathways, and their roles in diseases. While mainly covering the roles of the MIF homologs in cardiovascular, inflammatory, autoimmune, and metabolic diseases, we also discuss their involvement in cancer, sepsis, and chronic obstructive lung disease (COPD). A particular emphasis is laid upon potential mechanistic explanations for synergistic or cooperative activities of the MIF homologs in cancer, myocardial diseases, and COPD as opposed to emerging disparate or antagonistic activities in adipose tissue inflammation, metabolic diseases, and atherosclerosis. Lastly, we discuss potential future opportunities of jointly targeting MIF and MIF-2 in certain diseases, whereas precision targeting of only one homolog might be preferable in other conditions. Together, this article provides an update of the mechanisms and future therapeutic avenues of human MIF proteins with a focus on their emerging, surprisingly disparate activities, suggesting that MIF-2 displays a variety of activities that are distinct from those of MIF.

PCSK9 promotes the progression and metastasis of colon cancer cells through regulation of EMT and PI3K/AKT signaling in tumor cells and phenotypic polarization of macrophages

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is the ninth member of the proprotein convertase family that regulates lipoprotein homeostasis and altered PCSK9 expression was reportedly associated with tumor development and progression. This study assessed PCSK9 expression and functions in human colon cancer and then explored the underlying molecular events.

Methods

Colon cancer tissues were utilized for analysis of PCSK9 expression for association with clinicopathological factors from patients by immunohistochemistry assay. Manipulation of PCSK9 expression was assessed in vitro and in vivo for colon cancer cell proliferation, migration, and invasion using cell viability CCK-8, Transwell tumor cell migration and invasion, and wound-healing assays. Next, proteomic analysis, Western blot, qRT-PCR and Flow cytometry were conducted to assess downstream targets and tumor cell-derived PCSK9 action on macrophage polarization.

Results

PCSK9 expression was upregulated in colon cancer tissues versus the normal tissues, and associated with advanced tumor pathological grade. Knockdown of PCSK9 expression reduced colon cancer cell proliferation, migration, and invasion and suppressed tumor metastasis in vivo. PCSK9 directly or indirectly upregulated Snail 1 and in turn to downregulate E-cadherin expression, but upregulate N-cadherin and MMP9 levels and thereafter, to induce colon cancer cell epithelial-mesenchymal transition (EMT) process and activated PI3K/AKT signaling. However, PCSK9 overexpression showed the inverse effects on colon cancer cells. Knockdown of PCSK9 expression inhibited M2 macrophage polarization, but also promoted M1 macrophage polarization by reduction of lactate, protein lactylation and macrophage migration inhibitory factor (MIF) levels.

Conclusion

PCSK9 played an important role in the progression and metastasis of colon cancer by regulation of tumor cell EMT and PI3K/AKT signaling and in the phenotypic polarization of macrophages by mediating MIF and lactate levels. Targeting PCSK9 expression or activity could be used to effectively control colon cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02477-0.

Chronic inflammation, cancer development and immunotherapy

Chronic inflammation plays a pivotal role in cancer development. Cancer cells interact with adjacent cellular components (pro-inflammatory cells, intrinsic immune cells, stromal cells, etc.) and non-cellular components to form the inflammatory tumor microenvironment (TME). Interleukin 6 (IL-6), macrophage migration inhibitory factor (MIF), immune checkpoint factors and other pro-inflammatory cytokines produced by intrinsic immune cells in TME are the main mediators of intercellular communication in TME, which link chronic inflammation to cancer by stimulating different oncogenic signaling pathways and improving immune escape to promote cancer development. In parallel, the ability of monocytes, T regulatory cells (Tregs) and B regulatory cells (Bregs) to perform homeostatic tolerogenic functions is hijacked by cancer cells, leading to local or systemic immunosuppression. Standard treatments for advanced malignancies such as chemotherapy and radiotherapy have improved in the last decades. However, clinical outcomes of certain malignant cancers are not satisfactory due to drug resistance and side effects. The clinical application of immune checkpoint therapy (ICT) has brought hope to cancer treatment, although therapeutic efficacy are still limited due to the immunosuppressive microenvironment. Emerging evidences reveal that ideal therapies including clearance of tumor cells, disruption of tumor-induced immunosuppression by targeting suppressive TME as well as reactivation of anti-tumor T cells by ICT. Here, we review the impacts of the major pro-inflammatory cells, mediators and their downstream signaling molecules in TME on cancer development. We also discuss the application of targeting important components in the TME in the clinical management of cancer.

The role of macrophage subtypes and exosomes in immunomodulation

Macrophages are influential members of the innate immune system that can be reversibly polarized by different microenvironment signals. Cell polarization leads to a wide range of features, involving the migration, development, and organization of the cells. There is mounting evidence that macrophage polarization plays a key role in the initiation and development of a wide range of diseases. This study aims to give an overview of macrophage polarization, their different subtypes, and the importance of alternatively activated M2 macrophage and classically activated M1 macrophage in immune responses and pathological conditions. This review provides insight on the role of exosomes in M1/M2-like macrophage polarization and their potential as a promising therapeutic candidate.

Hypoxia-induced MIF induces dysregulation of lipid metabolism in Hep2 laryngocarcinoma through the IL-6/JAK-STAT pathway

Purpose

Hypoxia is a common feature of laryngocarcinoma. Alterations in lipid metabolism are an important metabolic rewiring phenomenon for malignant cells to maintain their rapid proliferation in the hypoxic microenvironment, which makes most cancers, including laryngocarcinoma, difficult to cure. However, the mechanisms involved in lipid metabolism in laryngocarcinoma is still unclear. This study aimed to clarify the changes in lipid metabolism of laryngocarcinoma cells under hypoxic conditions and explore the related mechanisms.

Methods

Hep2 cells were incubated in a normoxic or hypoxic environment (5% CO₂ and 1% O₂) at 37 °C for 24 h. CCK-8 cell viability assay and colony formation assay were performed to detect cells proliferation. And lipid metabolic indices including TG and NEFA were determined by kits. The mechanism involved in the regulation of lipid metabolism was explored by RNA-seq and bioinformatic analysis. The MIF inhibitor ISO-1 and JAK inhibitor XL019 were used to verify the mechanism. Finally, a tumour xenograft model was applied to further verify these results in vivo.

Results

Hypoxia promoted cell proliferation and increased the levels of TG and NEFA in Hep2 cells. Three genes, MIF, ENO2, and LDHA, that were screened by the intersection of hypoxia gene sets and fatty gene sets and were verified by qPCR. The MIF levels were elevated when cells were exposed to hypoxia. Through GSEA and RNA-seq analysis, the JAK/STAT pathway was screened. Hypoxia increased MIF levels and activated the IL-6/JAK/STAT pathway. The MIF inhibitor ISO-1inhibited cell proliferation under hypoxia and reversed the change in TG levels and IL-6 levels. And ISO-1 reversed the expression pattern of the screened genes in the JAK/STAT pathway. Finally, a tumour xenograft model further verified these results in vivo.

Conclusion

Hypoxia induced reprogramming of lipid metabolism in laryngocarcinoma cells through the MIF/IL-6/JAK-STAT pathway. This study revealed one mechanism that allows laryngocarcinoma cells to adapt to the hypoxic tumour microenvironment. Therefore, a drug targeting the MIF/IL-6/JAK-STAT pathway might be a promising therapeutic option for the treatment of laryngocarcinoma.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-022-01693-z.

Association Among MIF, IFIH1, and IL6 Gene Polymorphisms and Non-Segmental Vitiligo in a Chinese Han Population

Objective

The aim of the present study was to investigate the association of single-nucleotide polymorphisms (SNPs) in the macrophage migration inhibiting factor (MIF), interferon-induced Helicase C domain 1 (IFIH1), interleukin-6 (IL6) genes, circulating levels with non-segmental vitiligo (NSV) susceptibility in the Chinese population, and to analyze the relationships between gene polymorphisms and clinical characteristics of vitiligo.

Methods

In this study, genotyping was conducted in 155 patients with NSV and 117 unaffected controls using polymerase chain reaction and snapshot technique. Serum concentrations were determined by ELISA kit.

Results

There were strong associations between IFIH1 H843R and IL6-572G/C polymorphisms and NSV susceptibility (p = 0.013; p = 0.009). In contrast to previous studies, we found no significant difference in the MIF-173G/C polymorphism between the two groups. In addition, the frequency of allelic distribution for MIF-173G/C in patients with active NSV was significantly higher than stable NSV (p = 0.011), and IFIH1 H843R with early-onset (≤ 20), active or family history of NSV was significantly higher than late-onset (> 20), stable or no family history of NSV (p = 0.033; p = 0.045; p = 0.039). Serum concentrations of MIF were higher in patients with active NSV, serum IFIH1 and IL6 concentrations were related to the presence of polymorphisms in patients with NSV (p = 0.009; p = 0.011).

Conclusion

Our results suggested that IFIH1 H843R and IL6-572G/C gene polymorphisms and expression levels are obviously correlated with the onset of NSV. MIF-173G/C allele and serum concentrations may be associated with active NSV, and IFIH1 H843R allele may be associated with youth, active or family history of NSV.

Dissecting Intra-Tumoral Changes Following Immune Checkpoint Blockades in Intrahepatic Cholangiocarcinoma via Single-Cell Analysis

Purpose

To dissect the tumor ecosystem following immune checkpoint blockades (ICBs) in intrahepatic cholangiocarcinoma (ICC) at a single-cell level.

Methods

Single-cell RNA sequencing (scRNA-seq) data of 10 ICC patients for the ICB clinical trial were extracted from GSE125449 and systematically reanalyzed. Bulk RNA-seq data of 255 ICC patients were analyzed. Infiltration levels of SPP1⁺CD68⁺ tumor-associated macrophages (TAMs) were examined by dual immunofluorescence (IF) staining in 264 resected ICC samples. The correlation between SPP1⁺ TAMs and clinicopathological features as well as their prognostic significance was evaluated.

Results

Among the 10 patients, five received biopsy at baseline, and others were biopsied at different timings following ICBs. Single-cell transcriptomes for 5,931 cells were obtained. A tighter cellular communication network was observed in ICB-treated ICC. We found a newly emerging VEGF signaling mediated by PGF-VEGFR1 between cancer-associated fibroblasts (CAFs) and endothelial cells in ICC following ICBs. SPP1 expression was dramatically upregulated, and SPP1⁺ TAM gene signatures were enriched in TAMs receiving ICB therapy. We also identified SPP1⁺ TAMs as an independent adverse prognostic indicator for survival in ICC.

Conclusion

Our analyses provide an overview of the altered tumor ecosystem in ICC treated with ICBs and highlight the potential role of targeting CAFs and SPP1⁺TAMs in developing a more rational checkpoint blockade-based therapy for ICC.

MIF/SCL3A2 depletion inhibits the proliferation and metastasis of colorectal cancer cells via the AKT/GSK-3β pathway and cell iron death

This study investigated the mechanisms of migration inhibitory factor (MIF) and solute carrier family 3 member 2 (SLC3A2) in colorectal cancer progression. The levels of MIF and SLC3A2 expression in cells were measured by RT-qPCR. SW480 and SW620 cells were transfected with sh-MIF and sh-SLC3A2, respectively. MIF, SLC3A2, GPX4, E-cadherin and N-cadherin expression were detected by immunofluorescence (IF). CCK8 and Transwell assays were performed to detect cell proliferation and migration. Co-immunoprecipitation (CoIP) was used to measure the binding activity of MIF and SLC3A2. Finally, a nude mouse tumorigenicity assay was used to confirm the functions of MIF and SLC3A2 in colorectal cancer. Results showed that the levels of MIF and SLC3A2 expression were up-regulated in colorectal cancer cells. Inhibition of MIF or SLC3A2 expression prevented cell proliferation, migration, epithelial-mesenchymal transition (EMT) and invasion. In addition, knockdown of MIF and SLC3A2 promoted iron death in SW480 and SW620 cells. CoIP results showed that MIF and SLC3A2 directly interact with each other. Knockdown of both MIF and SLC3A2 inhibited tumour growth and metastasis via the AKT/GSK-3β pathway in vivo. The Akt/GSK-3β pathway was found to participate in regulating MIF and SLC3A2 both in vivo and in vitro. MIF and SLC3A2 might be potential biomarkers for monitoring the treatment of colorectal cancer.

Polymorphisms in the hypoxia inducible factor binding site of the macrophage migration inhibitory factor gene promoter in schizophrenia

Background

Macrophage migration inhibitory factor (MIF) is a multifunctional cytokine that promotes neurogenesis and neuroprotection. MIF is predominantly expressed in astrocytes in the brain. The serum MIF level and microsatellites/single nucleotide polymorphisms (SNPs) in the MIF gene promoter region are known to be associated with schizophrenia (SCZ). Interestingly, previous studies reported that hypoxia, an environmental risk factor for SCZ, induced MIF expression through binding of the hypoxia inducible factor (HIF)-1 to the hypoxia response element (HRE) in the MIF promoter.

Methods

We investigated the involvement of MIF in SCZ while focusing on the HIF pathway. First, we conducted an association study of the SNP rs17004038 (C>A) in the HRE of the MIF promoter between 1758 patients with SCZ and 1507 controls. Next, we investigated the effect of hypoxia on MIF expression in primary cultured astrocytes derived from neonatal mice forebrain.

Results

SNP rs17004038 was significantly associated with SCZ (p = 0.0424, odds ratio = 1.445), indicating that this SNP in the HRE of the MIF promoter was a genetic risk factor for SCZ. Hypoxia induced MIF mRNA expression and MIF protein production and increased HIF-1 binding to the MIF promoter, while the activity of the MIF promoter was suppressed by mutations in the HRE and by deletion of the HRE in astrocytes.

Conclusion

These results suggest that SNP rs17004038 in the HRE of the MIF promoter was significantly associated with SCZ and may be involved in the pathophysiology of SCZ via suppression of hypoxia and HIF pathway-induced MIF expression.

Neurological complications associated with Covid-19; molecular mechanisms and therapeutic approaches

With the progression of investigations on the pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), neurological complications have emerged as a critical aspect of the ongoing coronavirus disease 2019 (Covid‐19) pandemic. Besides the well‐known respiratory symptoms, many neurological manifestations such as anosmia/ageusia, headaches, dizziness, seizures, and strokes have been documented in hospitalised patients. The neurotropism background of coronaviruses has led to speculation that the neurological complications are caused by the direct invasion of SARS‐CoV‐2 into the nervous system. This invasion is proposed to occur through the infection of peripheral nerves or via systemic blood circulation, termed neuronal and haematogenous routes of invasion, respectively. On the other hand, aberrant immune responses and respiratory insufficiency associated with Covid‐19 are suggested to affect the nervous system indirectly. Deleterious roles of cytokine storm and hypoxic conditions in blood‐brain barrier disruption, coagulation abnormalities, and autoimmune neuropathies are well investigated in coronavirus infections, as well as Covid‐19. Here, we review the latest discoveries focussing on possible molecular mechanisms of direct and indirect impacts of SARS‐CoV‐2 on the nervous system and try to elucidate the link between some potential therapeutic strategies and the molecular pathways.

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.

Multifaceted interconnections between macrophage migration inhibitory factor and psychiatric disorders

Inflammation is involved in the pathogenesis of psychiatric disorders. Many previous studies have defined the important roles of inflammatory factors in the pathogenesis, diagnosis, and treatment outcomes of psychiatric disorders. Macrophage migration inhibitory factor (MIF), a pro-inflammatory factor, has been gradually recognized to be involved in the development of neurological diseases in recent years. Our current review focuses on discussing the potential beneficial and detrimental roles of MIF in psychiatric disorders. We will provide new mechanistic insights for the development of potential diagnostic and therapeutic biomarkers based on MIF for psychiatric diseases.

Uveal melanoma exosomes induce a pro-metastatic microenvironment through macrophage migration inhibitory factor (MIF)

Uveal melanoma (UM) is a rare melanoma subtype different from cutaneous melanoma, with high incidence of liver metastasis and poor prognosis. Cancer cell derived extracellular vesicles (EVs) have been shown to induce pro-inflammatory and pro-metastatic signaling in the tumor microenvironment and at distant sites. The characterization of UM exosome cargo and its role in metastatic spread is essential to identify targets and intervene in the early stages of metastatic development. Our study characterizes the proteomic content of UM exosomes and identified the presence of markers with metastatic properties. We demonstrated that UM exosomes induce activation of cell signaling pathways and the release of cytokines and growth factors from hepatocytes. These exosome-stimulated liver cells could in turn induce migration of UM cells, confirming that the exosomes have a functional role in the crosstalk between these two cell types. We found that the pro-inflammatory cytokine macrophage migration inhibitory factor (MIF) was a major player in these mechanisms and its blockade inhibited cell migration in co-culture with exosome-stimulated hepatocytes and prevented the development of metastases in vivo. Targeting MIF in the early stages of metastasis may represent a novel adjuvant drug therapy to prevent metastatic spread in uveal melanoma. Implications: This study provides the first in vivo evidence that MIF inhibition may serve as a novel adjuvant drug therapy to prevent metastasis in uveal melanoma.

Bioinformatics reveal macrophages marker genes signature in breast cancer to predict prognosis

Background: Breast cancer is a pivotal cause of global women cancer death. Immunotherapy has become a promising means to cure breast cancer. As constitutes of immune microenvironment of breast cancer, macrophages exert complicated functions in the tumour development and treatment. This study aims to develop a prognostic macrophage marker genes signature (MMGS).Methods: Single cell RNA sequence data analysis was performed to identify macrophage marker genes in breast cancer. TCGA database was used to construct MMGS model as a training cohort, and GSE96058 dataset was used to validate the MMGS as a validation cohort.Results: Genes included in the MMGS model were: SERPINA1, CD74, STX11, ADAM9, CD24, NFKBIA, PGK1. MMGS risk score stratified by overall survival of patients divided them into high- and low-risk groups. And MMGS risk score remained independent prognostic factor in multivariate analysis after adjusting for classical clinical factors in both training and validation cohorts. Besides, hormone receptors negative and human epidermal growth factor receptor 2 (HER2) positive patients had higher risk score. MMGS showed better distinguishing capability between high-risk and low-risk groups in hormone receptor positive and HER2 negative subgroup.Conclusion: MMGS provides a new understanding of immune cell marker genes in breast cancer prognosis and may offer reference for immunotherapy decision for breast cancer patients.

The modulating effect of methoxy-derivatives of 2'-hydroxychalcones on the release of IL-8, MIF, VCAM-1 and ICAM-1 by colon cancer cells

Colon cancer is one of the leading causes of death in the world. The search for effective and minimally invasive methods of treating colon cancer is the aim of modern medicine. Chalcones and their derivatives have shown an anticancer activity. The aim of the study was to evaluate the effect of methoxy-derivatives of 2'-hydroxychalcones: 2'-hydroxy-3"-methoxychalcone (TJ3), 2'-hydroxy-2"-methoxychalcone (TJ6) and 2'-hydroxy-4"-metoxychalcone (TJ7) at the concentrations of 10 µM and 25 µM on the release of IL-8, MIF, VCAM-1, ICAM-1 by colon cancer SW480 and SW620 cell lines. The cytokines and adhesion molecules were detected using the Bio-Plex Magnetic Luminex Assay and the Bio-Plex Suspension Array System. Our results showed that all tested methoxy-derivatives of 2'-hydroxychalcone compounds significantly reduced ICAM-1 released by SW480 cancer cells. The tested compounds at both concentrations did not significantly affect VCAM-1 released by SW480 and SW620 cancer cell lines. All methoxy-derivatives significantly reduced the concentration of MIF in dose dependent manner on SW480 cells. The TJ3 at the concentration of 25 µM significantly decreased IL-8 secreted by SW480 and SW620 cancer cells. Our results demonstrated that tested methoxy-derivatives of 2'-hydroxychalcones showed modulating effect on colon cancer cells.

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

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

Macrophage migration inhibitory factor (MIF): 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.

Targeting Adipokines in Obesity-Related Tumors

Obesity, a global epidemic, is an independent risk factor for the occurrence and development of a variety of tumors, such as breast cancer, pancreatic cancer, ovarian cancer and colorectal cancer. Adipocytes are important endocrine cells in the tumor microenvironment of obesity-related tumors, which can secrete a variety of adipokines (such as leptin, adiponectin, estrogen, resistin, MIF and MCP-1, etc.), among which leptin, adiponectin and estrogen are the most in-depth and valuable ones. These adipokines are closely related to tumorigenesis and the progression of tumors. In recent years, more and more studies have shown that under chronic inflammatory conditions such as obesity, adipocytes secrete more adipokines to promote the tumorigenesis and development of tumors. However, it is worth noting that although adiponectin is also secreted by adipocytes, it has an anti-tumor effect, and can cross-talk with other adipokines (such as leptin and estrogen) and insulin to play an anti-tumor effect together. In addition, obesity is the main cause of insulin resistance, which can lead to the increase of the expression levels of insulin and insulin-like growth factor (IGF). As important regulators of blood glucose and lipid metabolism, insulin and IGF also play an important role in the progress of obesity related tumors. In view of the important role of adipokines secreted by adipocytes and insulin/IGF in tumors, this article not only elaborates leptin, adiponectin and estrogen secreted by adipocytes and their mechanism of action in the development of obesity- related tumors, but also introduces the relationship between insulin/IGF, a regulator of lipid metabolism, and obesity related tumors. At the same time, it briefly describes the cancer-promoting mechanism of resistin, MIF and MCP-1 in obesity-related tumors, and finally summarizes the specific treatment opinions and measures for various adipokines and insulin/insulin-like growth factors in recent years.

Macrophage migration inhibitory factor: A promising oncogenic serological biomarker for oral squamous cell carcinoma

There are few reports in oral squamous cell carcinoma (OSCC) that indicate the expression of macrophage migration inhibitory factor (MIF) in tissues, serum, or saliva of patients with OSCC. The aim of this study was to evaluate the mRNA expression and protein of MIF in tissues and serum, respectively, in OSCC patients and its association with the TNM stage. A cross-sectional study was performed. Serum and tissues of 25 patients with OSCC and 25 healthy control subjects (HCS) were included to evaluate the MIF mRNA expression and protein serum levels by real-time PCR and ELISA, respectively. Serum MIF levels were significantly higher in OSCC compared with control subjects. Furthermore, in the OSCC group, MIF was significantly increased in accordance with tumor disease stage (TNM III–IV), as well as in poorly differentiated tumors. The mRNA showed significantly higher levels in HCS, as well as in more differentiated tumors. The results of this study suggest that MIF could be an indicator of severity and progression of OSCC. Further studies are required to explore the role of MIF as a serological biomarker for OSCC.

Chicago sky blue 6B (CSB6B), an allosteric inhibitor of macrophage migration inhibitory factor (MIF), suppresses osteoclastogenesis and promotes osteogenesis through the inhibition of the NF-κB signaling pathway

Macrophage migration inhibitory factor (MIF) is a pleiotropic pro-inflammatory mediator involved in various pathophysiological and inflammatory states. Accumulating line of evidence suggests a role for MIF in regulating bone metabolism and therefore a prime candidate for therapeutic targeting. In this study, we showed that Chicago sky blue 6B (CSB6B) suppresses RANKL-induced osteoclast and bone resorption in vitro via the inhibition of NF-κB signaling activation and promoting proteasome-mediated degradation of MIF. Consequently, the induction of NFATc1 was impaired resulting in downregulation of NFATc1-responsive osteoclast genes. We also demonstrated that CSB6B treatment enhanced primary calvarial osteoblast differentiation and bone mineralization in vitro via the suppression of NF-κB activation and upregulation of Runx expression. Using two murine models of osteolytic bone disorders, we further showed that administration of CSB6B protected mice against pathological inflammatoryc calvarial bone destruction induced by titanium particles mice as well as estrogen-deficiency induced bone loss as a result of ovariectomy. Together, as an MIF inhibitor, CSB6B can inhibit osteoclast differentiation and bone resorption function and enhance the mineralization of osteoblasts through the inhibition of NF-κB pathway. MIF is a prime target for therapeutic targeting for the treatment of osteolytic bone disorders and the MIF inhibitor CSB6B could be potential anti-osteoporosis drug.

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

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

Autophagy inhibition in breast cancer cells induces ROS-mediated MIF expression and M1 macrophage polarization

Autophagy can function as a survival mechanism for cancer cells and therefore, its inhibition is currently being explored as a therapy for different cancer types. For breast cancer, triple negative breast cancer (TNBC) is the subtype most sensitive to the inhibition of autophagy; but its inhibition has also been shown to promote ROS-dependent secretion of macrophage migration inhibitory factor (MIF), a pro-tumorigenic cytokine. In this work, we explore the role of MIF in breast cancer, the mechanism by which autophagy inhibition promotes MIF secretion and its effects on neighboring cancer cell signaling and macrophage polarization. We analyzed MIF mRNA expression levels in tumors from breast cancer patients from different subtypes and found that Luminal B, HER2 and Basal subtypes, which are associated to high proliferation, displayed high MIF levels. However, MIF expression had no prognostic relevance in any breast cancer subtype. In addition, we found that autophagy inhibition in 66cl4 TNBC cells increased intracellular Reactive Oxygen Species (ROS) levels, which increased MIF expression and secretion. MIF secreted from 66cl4 TNBC cells induced the activation of MIF-regulated pathways in syngeneic cell lines, increasing Akt phosphorylation in 4T1 cells and ERK phosphorylation in 67NR cells. Regarding MIF/ chemokine receptors, higher levels of CD74 and CXCR2 were found in TNBC tumor cell lines when compared to non-tumorigenic cells and CXCR7 was elevated in the highly metastatic 4T1 cell line. Finally, secreted MIF from autophagy deficient 66cl4 cells induced macrophage polarization towards the M1 subtype. Together, our results indicate an important role for the inhibition of autophagy in the regulation of ROS-mediated MIF gene expression and secretion, with paracrine effects on cancer cell signaling and pro-inflammatory repercussions in macrophage M1 polarization. This data should be considered when considering the inhibition of autophagy as a therapy for different types of cancer.

Intratumor Heterogeneity of MIF Expression Correlates With Extramedullary Involvement of Multiple Myeloma

Macrophage migration inhibitory factor (MIF) has been shown to promote disease progression in many malignancies, including multiple myeloma (MM). We previously reported that MIF regulates MM bone marrow homing and knockdown of MIF favors the extramedullary myeloma formation in mice. Here, based on MIF immunostaining of myeloma cells in paired intramedullary and extramedullary biopsies from 17 patients, we found lower MIF intensity in extramedullary MM (EMM) versus intramedullary MM (IMM). Flow cytometry and histology analysis in xenograft models showed a portion of inoculated human MM cells lost their MIF expression (MIF^Low) in vivo. Of note, IMM had dominantly MIF^High cells, while EMM showed a significantly increased ratio of MIF^Low cells. Furthermore, we harvested the extramedullary human MM cells from a mouse and generated single-cell transcriptomic data. The developmental trajectories of MM cells from the MIF^High to MIF^Low state were indicated. The MIF^High cells featured higher proliferation. The MIF^Low ones were more quiescent and harbored abundant ribosomal protein genes. Our findings identified in vivo differential regulation of MIF expression in MM and suggested a potential pathogenic role of MIF in the extramedullary spread of disease.

MIF promoter polymorphism increases peripheral blood expression levels, contributing to increased susceptibility and poor prognosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world. The etiology and pathogenesis of HCC remain unclear. Macrophage migration inhibitory factor (MIF) plays a critical role in the pathogenesis of hepatocellular carcinoma. The association between MIF polymorphisms and its expression level in HCC has rarely been demonstrated. In the present study, the peripheral blood of 202 patients with HCC (HCC group), 242 patients with chronic hepatitis B (CHB group), 215 patients with liver cirrhosis (LC group) and 227 healthy volunteers (normal group) were collected, DNA was extracted and the target fragment of MIF gene was amplified using PCR. The products were then sequenced, and the expression levels of MIF protein were tested using ELISA. The results showed that the MIF rs755622 polymorphism was associated with an increased susceptibility and metastasis of HCC, and that the genotypes GC and CC were associated with poor prognosis of HCC. Compared with the normal, CHB and LC groups, the expression of MIF in the peripheral blood of the HCC group was significantly increased, and the high expression was associated with to poor prognosis. In the HCC group, MIF protein levels for genotypes GC and CC were increased compared with those of genotype GG. The current study indicated that the MIF rs755622 polymorphism is associated with susceptibility and metastasis of HCC, and that the GC and CC genotypes may be indicators of poor prognosis, which may be ascribed to the MIF rs755622 polymorphism leading to elevated MIF protein expression in peripheral blood.

Musashi-1 Regulates MIF1-Mediated M2 Macrophage Polarization in Promoting Glioblastoma Progression

Simple Summary

Glioblastoma (GBM) is the most lethal type of brain cancer. It is well known that the malignancy of cancers is dependent not only on the oncogenic properties of the tumor cells, but also on the composition of the tumor microenvironment, which includes macrophages of the immune system. The prevalence of M2 type macrophages usually promotes tumor progression as opposed to tumor-suppressing function of M1 type macrophages. In our previous studies, we identified Musashi-1 (MSI1) RNA-binding protein as a principal oncogenic factor in GBM. In this study, in a pursuit of finding secreted factors that may alter tumor microenvironment in GBM, we identified MIF1 cytokine to be positively regulated by MSI1. Moreover, we found that MSI1-mediated MIF1 secretion promotes differentiation of macrophages into pro-oncogenic M2 phenotype. The oncogenic role of MSI1/MIF1/M2 macrophage regulatory axis was also confirmed in GBM mouse models, which makes it a promising target for novel drug discovery.

Abstract

Glioblastoma (GBM) is the most malignant brain tumor which is characterized by high proliferation and migration capacity. The poor survival rate has been attributed to limitations of the current standard therapies. The search for novel biological targets that can effectively hamper tumor progression remains extremely challenging. Previous studies indicated that tumor-associated macrophages (TAMs) are the abundant elements in the tumor microenvironment that are closely implicated in glioma progression and tumor pathogenesis. M2 type TAMs are immunosuppressive and promote GBM proliferation. RNA-binding protein Musashi-1 (MSI1) has recently been identified as a marker of neural stem/progenitor cells, and its high expression has been shown to correlate with the growth of GBM. Nevertheless, the relationship between MSI1 and TAMs in GBM is still unknown. Thus, in our present study, we aimed to investigate the molecular interplay between MSI1 and TAMs in contributing to GBM tumorigenesis. Our data revealed that the secretion of macrophage inhibitory factor 1 (MIF1) is significantly upregulated by MSI1 overexpression in vitro. Importantly, M2 surface markers of THP-1-derived macrophages were induced by recombinant MIF1 and reduced by using MIF1 inhibitor (S,R)-3-(4-hHydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid (ISO-1). Furthermore, GBM tumor model data suggested that the tumor growth, MIF1 expression and M2 macrophage population were significantly downregulated when MSI1 expression was silenced in vivo. Collectively, our findings identified a novel role of MSI1 in the secretion of MIF1 and the consequent polarization of macrophages into the M2 phenotype in promoting GBM tumor progression.

Macrophage migration inhibitory factor (MIF) enhances hypochlorous acid production in phagocytic neutrophils

BACKGROUND

Macrophage migration inhibitory factor (MIF) is an important immuno-regulatory cytokine and is elevated in inflammatory conditions. Neutrophils are the first immune cells to migrate to sites of infection and inflammation, where they generate, among other mediators, the potent oxidant hypochlorous acid (HOCl). Here, we investigated the impact of MIF on HOCl production in neutrophils in response to phagocytic stimuli.

METHODS

Production of HOCl during phagocytosis of zymosan was determined using the specific fluorescent probe R19-S in combination with flow cytometry and live cell microscopy. The rate of phagocytosis was monitored using fluorescently-labeled zymosan. Alternatively, HOCl production was assessed during phagocytosis of Pseudomonas aeruginosa by measuring the oxidation of bacterial glutathione to the HOCl-specific product glutathione sulfonamide. Formation of neutrophil extracellular traps (NETs), an oxidant-dependent process, was quantified using a SYTOX Green plate assay.

RESULTS

Exposure of human neutrophils to MIF doubled the proportion of neutrophils producing HOCl during early stages of zymosan phagocytosis, and the concentration of HOCl produced was greater. During phagocytosis of P. aeruginosa, a greater fraction of bacterial glutathione was oxidized to glutathione sulfonamide in MIF-treated compared to control neutrophils. The ability of MIF to increase neutrophil HOCl production was independent of the rate of phagocytosis and could be blocked by the MIF inhibitor 4-IPP. Neutrophils pre-treated with MIF produced more NETs than control cells in response to PMA.

CONCLUSION

Our results suggest a role for MIF in potentiating HOCl production in neutrophils in response to phagocytic stimuli. We propose that this newly discovered activity of MIF contributes to its role in mediating the inflammatory response and enhances host defence.

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.