High-dose corticosteroid administration induces increase of serum macrophage migration inhibitory factor in patients with Vogt-Koyanagi-Harada's disease

The roles of macrophage migration inhibitory factor in retinal diseases

Macrophage migration inhibitory factor (MIF), a multifunctional cytokine, is secreted by various cells and participates in inflammatory reactions, including innate and adaptive immunity. There are some evidences that MIF is involved in many vitreoretinal diseases. For example, MIF can exacerbate many types of uveitis; measurements of MIF levels can be used to monitor the effectiveness of uveitis treatment. MIF also alleviates trauma-induced and glaucoma-induced optic nerve damage. Furthermore, MIF is critical for retinal/choroidal neovascularization, especially complex neovascularization. MIF exacerbates retinal degeneration; thus, anti-MIF therapy may help to mitigate retinal degeneration. MIF protects uveal melanoma from attacks by natural killer cells. The mechanism underlying the effects of MIF in these diseases has been demonstrated: it binds to cluster of differentiation 74, inhibits the c-Jun N-terminal kinase pathway, and triggers mitogen-activated protein kinases, extracellular signal-regulated kinase-1/2, and the phosphoinositide-3-kinase/Akt pathway. MIF also upregulates Toll-like receptor 4 and activates the nuclear factor kappa-B signaling pathway. This review focuses on the structure and function of MIF and its receptors, including the effects of MIF on uveal inflammation, retinal degeneration, optic neuropathy, retinal/choroidal neovascularization, and uveal melanoma.

Assessment of the involvement of the macrophage migration inhibitory factor-glucocorticoid regulatory dyad in the expression of matrix metalloproteinase-2 during periodontitis

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine and counter-regulator of endogenous glucocorticoids (GCs). It is implicated in acute and chronic inflammatory diseases. This study investigated the role of the MIF-GC regulatory dyad in the expression and release of matrix metalloproteinase-2 (MMP-2) during periodontitis, in vivo and in vitro. In a Mif-knockout (KO) mouse model of ligature-induced periodontitis, gingival tissues and blood were collected and analysed for levels of interleukin-6 (IL-6), MIF, MMP-2, and corticosterone. In addition, human gingival fibroblasts (HGFs) were tested for production of IL-6 and MMP-2 after stimulation with hydrocortisone (HC), MIF, tumour necrosis factor-alpha (TNF-α), or Fusobacterium nucleatum, a pathogen known to elicit immune responses during periodontitis. Wild-type (WT) mice showed a local and systemic increase of MIF levels during inflammation, which was confirmed by increased local IL-6 concentrations. Systemic GC levels were reduced in WT and Mif-KO mice during inflammation, with overall lower concentrations in Mif-KO mice. In vivo and in vitro, MMP-2 production was not dependent on MIF or inflammatory stimuli, but was inhibited by HC. Therefore, MIF does not appear to stimulate expression of MMP-2 in the gingival tissues, whereas GC upregulates MIF and downregulates MMP-2. Our findings further suggest that MIF may regulate systemic GC levels.

Candidate genes expression profile associated with antidepressants response in the GENDEP study: differentiating between baseline 'predictors' and longitudinal 'targets'

To improve the 'personalized-medicine' approach to the treatment of depression, we need to identify biomarkers that, assessed before starting treatment, predict future response to antidepressants ('predictors'), as well as biomarkers that are targeted by antidepressants and change longitudinally during the treatment ('targets'). In this study, we tested the leukocyte mRNA expression levels of genes belonging to glucocorticoid receptor (GR) function (FKBP-4, FKBP-5, and GR), inflammation (interleukin (IL)-1α, IL-1β, IL-4, IL-6, IL-7, IL-8, IL-10, macrophage inhibiting factor (MIF), and tumor necrosis factor (TNF)-α), and neuroplasticity (brain-derived neurotrophic factor (BDNF), p11 and VGF), in healthy controls (n=34) and depressed patients (n=74), before and after 8 weeks of treatment with escitalopram or nortriptyline, as part of the Genome-based Therapeutic Drugs for Depression study. Non-responders had higher baseline mRNA levels of IL-1β (+33%), MIF (+48%), and TNF-α (+39%). Antidepressants reduced the levels of IL-1β (-6%) and MIF (-24%), and increased the levels of GR (+5%) and p11 (+8%), but these changes were not associated with treatment response. In contrast, successful antidepressant response was associated with a reduction in the levels of IL-6 (-9%) and of FKBP5 (-11%), and with an increase in the levels of BDNF (+48%) and VGF (+20%)-that is, response was associated with changes in genes that did not predict, at the baseline, the response. Our findings indicate a dissociation between 'predictors' and 'targets' of antidepressant responders. Indeed, while higher levels of proinflammatory cytokines predict lack of future response to antidepressants, changes in inflammation associated with antidepressant response are not reflected by all cytokines at the same time. In contrast, modulation of the GR complex and of neuroplasticity is needed to observe a therapeutic antidepressant effect.

Tumour necrosis factor-α up-regulates macrophage migration inhibitory factor expression in endometrial stromal cells via the nuclear transcription factor NF-κB

BACKGROUND

A series of controlled changes including proliferation, secretion and menstrual shedding occur in the human endometrium during every normal menstrual cycle. Macrophage migration inhibitory factor (MIF), a multifunctional cytokine with numerous proinflammatory, immunomodulatory and angiogenic properties, appears to be expressed in the human endometrium and to follow a regulated cycle phase-dependent expression, but the mechanisms underlying endometrial MIF expression remain to be fully elucidated.

METHODS AND RESULTS

Results from enzyme-linked immunosorbent assay (ELISA) demonstrated a significant dose- and time-dependent increase in MIF secretion by human endometrial cells in response to tumour necrosis factor-alpha (TNF-alpha) (0.1-100 ng/ml). This increase was also observed at the mRNA level as shown by reverse transcription (RT)-PCR. Curcumin (10(-8) mol/l), a known nuclear factor (NF)-kappaB inhibitor, inhibited the TNF-alpha-induced pIkappaB phosphorylation as shown by western blotting, NF-kappaB translocation into the nucleus as shown by electrophoretic mobility shift assay, and MIF synthesis and secretion as measured by ELISA and RT-PCR. The expression of a dominant-negative NF-kappaB inhibitor (IkappaB) significantly decreased the TNF-alpha-induced MIF promoter activity as analysed by transient cell transfection.

CONCLUSIONS

These results indicate clearly that TNF-alpha up-regulates the expression of MIF in endometrial stromal cells. This took place possibly through NF-kappaB activation, and may play an important role in the physiology of the human endometrium.

Usefulness of quantifying serum KL-6 levels in the follow-up of uveitic patients with sarcoidosis

BACKGROUND

KL-6 is a human glycoprotein secreted by type II alveolar cells in the lung, and its serum levels increase in pneumonia of various causes. We previously reported that serum KL-6 levels in uveitis patients with sarcoidosis were significantly higher than those of other uveitis patients and healthy controls. Additionally, the combined measurement of serum KL-6 and angiotensin converting enzyme (ACE) was useful for screening uveitic patients to diagnose sarcoidosis. The purpose of the present study was to investigate the clinical usefulness of quantifying serum KL-6 levels for following-up the patients with sarcoidosis.

METHODS

Sera were obtained from 36 uveitic patients diagnosed with sarcoidosis and the same number of healthy volunteers. To examine the influence of systemic medication, we also collected blood samples from four more sarcoidosis patients, who were systemically treated with corticosteroid or angiotensin converting enzyme (ACE) inhibitor, an anti-hypertensive drug. The serum concentration of KL-6 was measured by a human KL-6 electrochemiluminescence immunoassay (ECLIA).

RESULTS

The mean KL-6 concentrations of sarcoidosis patients and healthy controls were 449.3+/-66.3 (mean+/-SE) and 192.1+/-11.3, respectively. The average levels of serum KL-6 were significantly elevated in sarcoidosis patients compared with healthy control subjects (P<0.001), and there were significant correlations between serum KL-6 and ACE levels in the patients with sarcoidosis (r=0.70 and P<0.0001). Moreover, serum KL-6 concentrations were less affected by systemic corticosteroid, and unaffected by ACE inhibitory drugs in contrast to ACE levels.

CONCLUSIONS

Measurement of serum KL-6 in the uveitic patients may be useful to follow-up the diagnosed sarcoidosis, as well as for diagnosing sarcoidosis, because the serum KL-6 level was well correlated with the ACE level, and less affected by systemic medication than ACE levels.

Macrophage migration inhibitory factor in allergic rhinitis: its identification in eosinophils at the site of inflammation

The aim of this study was to assess the potential role of macrophage migration inhibitory factor (MIF) in the pathogenesis of allergic rhinitis (AR). Serum MIF concentrations were measured by a specific enzyme-linked immunosorbent assay. In order to elucidate the cellular source of MIF, we performed double immunostaining of biopsy specimens of the nasal mucous membrane with markers for MIF and for inflammatory cells. The mean MIF level in sera from patients with AR was significantly higher than that in sera from healthy controls. Moreover, the levels were significantly correlated with the severity of the clinical symptoms. The majority of the MIF-positive cells at the site of allergic inflammation were eosinophils. These data suggest that MIF plays a role in the initiation and maintenance of AR. Eosinophils formed the largest population of MIF-producing cells; this finding suggests that they may be a major source of MIF at inflammatory sites in atopic disease.

Macrophage migration inhibitory factor

Macrophage migration inhibitory factor (MIF) is a ubiquitous protein that is found in virtually all cells. Its precise function in the majority of cells is not known, but studies performed over the last decade indicate that it is a critical upstream regulator of the innate and acquired immune response. MIF is released under a variety of circumstances, regulates cytokine secretion and the expression of receptors that are involved in innate immunity, inhibits p53 function, and activates components of the mitogen-activated protein kinase and Jun-activation domain-binding protein-1 (Jab-1) pathways. Compelling in vitro and in vivo evidence has focused attention on this protein as a new therapeutic target for inflammatory and autoimmune diseases. Unique structural features, including an intrinsic catalytic activity, offer attractive opportunities for the discovery and design of therapeutic MIF inhibitors.

Neuroendocrine properties of macrophage migration inhibitory factor (MIF)

The cytokine macrophage migration inhibitory factor (MIF) is produced by neuroendocrine and immune tissues and possesses several features that allow it to be characterized as a neuroendocrine mediator. Its pro-inflammatory action and its pathogenic role in inflammatory diseases, such as septic shock, arthritis and other diseases, have clearly been demonstrated and may be based in part on neuroendocrine mechanisms. Macrophage migration inhibitory factor possesses glucocorticoid-antagonist properties within the immune system and participates in the regulation of several endocrine circuits. This review summarizes the current state of MIF research and focuses on MIF expression and function in nervous and endocrine tissues.