Macrophage migration inhibitory factor may contribute to vasculopathy in systemic sclerosis

Digital ulcers associated with scleroderma: A major unmet medical need

Scleroderma or systemic sclerosis (SSc)-associated digital ischaemic complications, such as digital ulcers (SSc-DUs), appear relatively early during the disease course and are a major burden with substantial deterioration of quality of life. Expert rheumatologist and wound specialists have defined a DU; however, international application of the definition is still disorganised. Appearance of SSc-DUs is secondary to the onset of Raynaud's phenomenon and as a consequence, recommended first-line of treatment mainly includes vasodilators; however, many DUs are refractory to this treatment. Despite important practical issues, such as a lack of well-characterised SSc-wound healing animal model, significant efforts are needed to mechanistically understand the pathogenesis of SSc-DUs for developing clinically targetable disease modifying therapies.

Cellular and Molecular Diversity in Scleroderma

With the increasing armamentarium of high-throughput tools available at manageable cost, it is attractive and informative to determine the molecular underpinnings of patient heterogeneity in systemic sclerosis (SSc). Given the highly variable clinical outcomes of patients labelled with the same diagnosis, unravelling the cellular and molecular basis of disease heterogeneity will be crucial to predicting disease risk, stratifying management and ultimately informing a patient-centered precision medicine approach. Herein, we summarise the findings of the past several years in the fields of genomics, transcriptomics, and proteomics that contribute to unraveling the cellular and molecular heterogeneity of SSc. Expansion of these findings and their routine integration with quantitative analysis of histopathology and imaging studies into clinical care promise to inform a scientifically driven patient-centred personalized medicine approach to SSc in the near future.

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.

Flow cytometry evaluation of CD14/CD16 monocyte subpopulations in systemic sclerosis patients: a cross sectional controlled study

BACKGROUND

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by vasculopathy and fibrosis, which can be subclassified into diffuse cutaneous (dSSc) and limited cutaneous (lSSc) subtypes. Previous studies suggest that an increase in monocytes can be a hallmark of various inflammatory diseases, including SSc. Our aim was to evaluate circulating blood monocyte subpopulations (classical, intermediate and non-classical) of SSc patients and their possible association with disease manifestations.

METHODS

Fifty consecutive patients fulfilling the 2013 ACR/EULAR classification criteria for SSc were included in a cross-sectional study. Monocyte subpopulations were identified based on their expression of CD64, CD14 and CD16, evaluated by flow cytometry, and were correlated with the clinical characteristics of the patients; furthermore, the expression of HLA-DR, CD163, CD169 and CD206 in the monocytes was studied. Thirty-eight age- and sex-matched healthy individuals were recruited as a control group.

RESULTS

SSc patients had an increased number of circulating peripheral blood monocytes with an activated phenotypic profile compared to healthy subjects. Absolute counts of CD16+ (intermediary and non-classical) monocyte subpopulations were higher in SSc patients. There was no association between monocyte subpopulations and the clinical manifestations evaluated.

CONCLUSION

We identified higher counts of all monocyte subpopulations in SSc patients compared to the control group. There was no association between monocyte subpopulations and major fibrotic manifestations. CD169 was shown to be more representative in dSSc, being a promising marker for differentiating disease subtypes.

Macrophage migration inhibitory factor polymorphisms are a potential susceptibility marker in systemic sclerosis from southern Mexican population: association with MIF mRNA expression and cytokine profile

INTRODUCTION

Systemic sclerosis (SSc) is a complex autoimmune disease, characterized by microvascular lesions, autoimmunity, and fibrosis. It is suggested that MIF participates in the amplification of the proinflammatory process in SSc; moreover, the promoter polymorphisms - 794 CATT_5-8 (rs5844572) and - 173G>C (rs755622) in the MIF gene have been associated with an increase in MIF serum levels in several autoimmune diseases. The aim of this study was to analyze the relationship of the - 794 CATT_5-8 and - 173G>C MIF polymorphisms with mRNA expression, MIF serum levels, and the Th1/Th2/Th17 cytokine profile in SSc.

MATERIALS AND METHODS

A case-control study was carried out that included 50 patients with SSc and 100 control subjects (CS). Both polymorphisms were genotyped by PCR and PCR-RFLP. MIF levels were measured by ELISA kit. The cytokine profile and the MIF mRNA expression were quantified by BioPlex MagPix system and real-time PCR, respectively.

RESULTS

An association between the - 794 CATT₇ and - 173*C MIF alleles and the 7C haplotype with SSc susceptibility was found (p < 0.05). Also, the 7C haplotype was associated with increased MIF mRNA expression (p = 0.03) in SSc. In addition, an increase of IL-1β and IL-6 serum levels in SSc patients was found as well as a positive correlation between MIF serum levels and Th1 and Th17 cytokine profiles.

CONCLUSION

The MIF 7C haplotype is a susceptibility marker for SSc in the southern Mexican population and is associated with MIF mRNA expression. Moreover, there is a positive correlation between MIF serum levels and Th1 and Th17 inflammatory response in SSc.

Analysis of serum macrophage migration inhibitory factor and D-dopachrome tautomerase in systemic sclerosis

Objectives

Macrophage migration inhibitory factor (MIF) and D‐dopachrome tautomerase (DDT), members of the same cytokine superfamily, are linked to the pathogenesis of a number of inflammatory diseases. The aim of this study was to investigate their clinical relevance in systemic sclerosis (SSc).

Methods

Serum MIF and DDT were quantified in 105 SSc patients by ELISA and levels compared to healthy controls (HC) (47) and patients with systemic lupus erythematosus (SLE) (184). Clinical parameters included organ involvement, serum laboratory markers and results of pulmonary function tests, and overall disease activity assessed using the European Scleroderma Trials and Research group (EUSTAR) activity index.

Results

There was no significant difference in serum DDT concentrations between patients with SSc and HC. However, serum MIF was significantly increased in SSc compared to both HC and SLE cohorts. Serum MIF was increased in SSc patients with low forced vital capacity (FVC) and was also associated with the use of angiotensin II receptor blockers and beta blockers in SSc, confirmed after adjusting for the presence of systemic hypertension and low FVC. Serum DDT was significantly higher in SSc patients with low FEV1 and negatively correlated with EUSTAR score, particularly in patients with limited disease.

Conclusion

Although not significantly linked to specific clinical parameters, serum MIF was significantly higher in SSc patients than in HC and SLE patients, suggesting a fundamental role for MIF in SSc. DDT, while closely related to MIF, did not show a similar expression profile, suggesting functional differences between these molecules.

Macrophage migration inhibitory factor contributes to the pathogenesis of benign lymphoepithelial lesion of the lacrimal gland

Background

Benign Lymphoepithelial Lesion (BLEL) is a rare disease observed in the adult population. Despite the growing numbers of people suffering from BLEL, the etiology and mechanisms underlying its pathogenesis remain unknown.

Methods

In the present study, we used gene and cytokines expression profiling, western blot and immunohistochemistry to get further insight into the cellular and molecular mechanisms involved in the pathogenesis of BLEL of the lacrimal gland.

Results

The results showed that Macrophage Migration Inhibitory Factor (MIF) was the most highly expressed cytokine in BLEL, and its expression positively correlated with the expression of Th2 and Th17 cells cytokines. MIF was found to regulate biological functions and pathways involved in BLEL pathogenesis, such as proliferation, resistance to apoptosis, MAPK and PI3K/Akt pathways. We also found that MIF promotes fibrosis in BLEL by inducing BLEL fibroblast differentiation into myofibroblasts as well as the synthesis and the deposit of extracellular matrix in BLEL tissues.

Conclusions

Our findings demonstrate the contribution of MIF to the pathogenesis of BLEL of the lacrimal gland and suggested MIF as a promising therapeutic target for its treatment.

Electronic supplementary material

The online version of this article (10.1186/s12964-018-0284-4) contains supplementary material, which is available to authorized users.

An MIF Promoter Polymorphism Is Associated with Susceptibility to Pulmonary Arterial Hypertension in Diffuse Cutaneous Systemic Sclerosis

Objective.

Systemic sclerosis (SSc) is a fibrotic immune-mediated disease of unknown etiology. Among its clinical manifestations, pulmonary involvement is the leading cause of mortality in patients with SSc. However, the genetic factors involved in lung complication are not well defined. We aimed to review the association of the MIF gene, which encodes a cytokine implicated in idiopathic pulmonary hypertension among other diseases, with the susceptibility and clinical expression of SSc, in addition to testing the association of this polymorphism with SSc-related pulmonary involvement.

Methods.

A total of 4392 patients with SSc and 16,591 unaffected controls from 6 cohorts of European origin were genotyped for the MIF promoter variant rs755622. An inverse variance method was used to metaanalyze the data.

Results.

A statistically significant increase of the MIF rs755622*C allele frequency compared with controls was observed in the subgroups of patients with diffuse cutaneous SSc (dcSSc) and with pulmonary arterial hypertension (PAH) independently (dcSSc: p = 3.20E–2, OR 1.13; PAH: p = 2.19E–02, OR 1.32). However, our data revealed a stronger effect size with the subset of patients with SSc showing both clinical manifestations (dcSSc with PAH: p = 6.91E–3, OR 2.05).

Conclusion.

We reviewed the association of the MIF rs755622*C allele with SSc and described a phenotype-specific association of this variant with the susceptibility to develop PAH in patients with dcSSc.

Macrophage migration inhibitory factor as a novel biomarker of portopulmonary hypertension

Portopulmonary hypertension (POPH) is a poorly understood complication of liver disease associated with significant morbidity and mortality. We sought to identify novel biomarkers of POPH disease presence and severity. We performed a prospective, multicenter, case-control study involving patients with liver disease undergoing right heart catheterization. POPH cases were defined as a mean pulmonary arterial pressure (mPAP) ≥25 mmHg and pulmonary vascular resistance (PVR) >240 dynes˙s˙cm^-5. Plasma samples were collected from the systemic and pulmonary circulation, and antibody microarray was used to identify biomarkers. Characterization and validation of a candidate cytokine, macrophage migration inhibitory factor (MIF), was performed using enzyme-linked immunosorbent assay. Continuous variables were compared using a Mann-Whitney U test and correlated with disease severity using Spearman correlation. MIF levels were elevated in both the systemic and pulmonary circulation in patients with POPH compared with controls (median MIF level [interquartile range] in systemic circulation: 46.68 ng/mL [32.31-76.04] vs. 31.19 ng/mL [26.92-42.17], P = 0.009; in pulmonary circulation: 49.59 ng/mL [35.90-108.80] vs. 37.78 [21.78-45.53], P = 0.002). In patients with POPH, MIF levels were positively correlated with PVR (r = 0.58, P = 0.006) and inversely correlated with cardiac output (r = -0.57, P = 0.007). MIF >60 ng/mL or tricuspid regurgitation gradient >50 mmHg had a 92% sensitivity and specificity for the diagnosis of POPH, with a positive predictive value of 86% and a negative predictive value of 96%. MIF is a promising novel biomarker of POPH disease presence and severity in patients with liver disease and portal hypertension.

The role of macrophage migration inhibitory factor in mast cell-stimulated fibroblast proliferation and collagen production

Current clinical and translational studies have shown that mast cell plays a pivotal role in multiple fibrotic diseases including scleroderma. However, the lack of mature human mast cell culture model exhibits a major obstacle for further dissection of cytokines and signaling molecules required for mast cell mediated fibrosis in various diseases. Macrophage Migration Inhibitory Factor is a mast cell released pro-inflammatory cytokine which is deregulated in scleroderma patients and is also involved in non-scleroderma related fibrosis. In the current study, we successfully generated a practical and reliable human mast cell culture system with bone marrow CD34+ hematopietic precursors. The derivative mast cell is normal in terms of both morphology and function as manifested by normal degranulation. More importantly, we were able to show mast cell conditioned medium as well as MIF supplementation augments fibroblast proliferation and collagen synthesis. This positive regulatory effect of mast cell conditioned medium can be dampened by MIF antibody. In addition, MIF-knockdown significantly inhibits pro-fibrotic activities of CD34+ hematopietic precursor derived mast cells. These data strongly suggest that mast cell released MIF is required for mast cell mediated fibrogenic activities. The current manuscript seems to be the first mechanistic report showing the significance of MIF in mast cell mediated fibrosis, which may pave the way for the development of potential MIF-targeted therapy for fibrotic diseases to a further extent. Moreover, we strongly believe mast cell culture and differentiation model as well as corresponding genetic manipulation methodology will be helpful in characterizing novel mast cell based therapeutic targets.

Systemic sclerosis biomarkers discovered using mass-spectrometry-based proteomics: a systematic review

CONTEXT

Systemic sclerosis (SSc) is an autoimmune disease with incompletely known physiopathology. There is a great challenge to predict its course and therapeutic response using biomarkers.

OBJECTIVE

To critically review proteomic biomarkers discovered from biological specimens from systemic sclerosis patients using mass spectrometry technologies.

METHODS

Medline and Embase databases were searched in February 2014.

RESULTS

Out of the 199 records retrieved, a total of 20 records were included, identifying 116 candidate proteomic biomarkers.

CONCLUSION

Research in SSc proteomic biomarkers should focus on biomarker validation, as there are valuable mass-spectrometry proteomics studies in the literature.

Role of macrophage migration inhibitory factor in the proliferation of smooth muscle cell in pulmonary hypertension

Pulmonary hypertension (PH) contributes to the mortality of patients with lung and heart diseases. However, the underlying mechanism has not been completely elucidated. Accumulating evidence suggests that inflammatory response may be involved in the pathogenesis of PH. Macrophage migration inhibitory factor (MIF) is a critical upstream inflammatory mediator which promotes a broad range of pathophysiological processes. The aim of the study was to investigate the role of MIF in the pulmonary vascular remodeling of hypoxia-induced PH. We found that MIF mRNA and protein expression was increased in the lung tissues from hypoxic pulmonary hypertensive rats. Intensive immunoreactivity for MIF was observed in smooth muscle cells of large pulmonary arteries (PAs), endothelial cells of small PAs, and inflammatory cells of hypoxic lungs. MIF participated in the hypoxia-induced PASMCs proliferation, and it could directly stimulate proliferation of these cells. MIF-induced enhanced growth of PASMCs was attenuated by MEK and JNK inhibitor. Besides, MIF antagonist ISO-1 suppressed the ERK1/2 and JNK phosphorylation induced by MIF. In conclusion, the current finding suggested that MIF may act on the proliferation of PASMCs through the activation of the ERK1/2 and JNK pathways, which contributes to hypoxic pulmonary hypertension.

MIF: a key player in cutaneous biology and wound healing

Owing to its implication in a range of pathological conditions, including asthma, rheumatoid arthritis, atherosclerosis, inflammatory bowel disease and cancer, the pleiotropic cytokine macrophage migration inhibitory factor (MIF) has been the subject of intensive recent investigation. In the field of dermatology, MIF is believed to be a detrimental factor in diseases such as systemic sclerosis, atopic dermatitis, psoriasis, eczema and UV radiation damage. However, its contribution to other aspects of cutaneous biology is currently unclear. Although its expression in intact skin is well characterized, little is known about MIF's role in cutaneous homoeostasis. However, recent data do identify MIF as a key player in the immune privilege of hair follicles. Similarly, although MIF is rapidly released and its local expression significantly induced upon wounding, its primary role in the ensuing repair process remains a source of contention. MIF has been identified as being a key effector of the beneficial effects of estrogen on wound repair, yet studies employing Mif null mice, recombinant MIF, and neutralizing anti-MIF antibodies have failed to provide a consensus as to whether it benefits or inhibits healing. In fact MIF appears to be able to exert both positive and negative effects, with the cell-specific relevancy of MIF in wound healing still unclear. Thus, if MIF and/or its downstream targets are to be therapeutically useful in the context of cutaneous repair, more needs to be done to establish the nature and mechanism of action of MIF and its receptors in healing wounds.

Autoimmune diseases: MIF as a therapeutic target

IMPORTANCE OF THE FIELD

Autoimmune inflammatory diseases occur commonly in developed countries. The treatment of these diseases is usually non-curative and is aimed at suppressing inflammatory end-organ damage. Macrophage migration inhibitory factor (MIF) is a multipotent cytokine that has been implicated in the pathogenesis of numerous autoimmune inflammatory disorders. The selective targeting of MIF with either anti-MIF antibody or specific MIF antagonists may offer new therapeutic avenues for these diseases.

AREAS COVERED IN THIS REVIEW

Our aim is to discuss MIF-directed therapies as a novel therapeutic approach. The review covers literature from the past 10 years.

WHAT THE READER WILL GAIN

MIF inhibition has been shown to be efficacious in many experimental and pre-clinical studies of autoimmune inflammatory diseases. The close regulatory relationship between MIF and glucocorticoids makes therapeutic antagonism of MIF a potential steroid-sparing therapy in patients with refractory autoimmune diseases.

TAKE HOME MESSAGE

We expect that MIF antagonism by either small-molecule- or antibody-based approaches will find wide application in the treatment of autoimmune inflammatory diseases. Such therapy also may be informed by the MIF genotype of affected patients.