Functional polymorphisms of macrophage migration inhibitory factor as predictors of morbidity and mortality of pneumococcal meningitis

The human MIF polymorphism CATT7 enhances pro-inflammatory macrophage polarization in a clinically relevant model of allergic airway inflammation

High level expression of the pro-inflammatory cytokine macrophage migration inhibitory factor (MIF) has been associated with severe asthma. The role of MIF and its functional promotor polymorphism in innate immune training is currently unknown. Using novel humanized CATT7 MIF mice, this study is the first to investigate the effect of MIF on bone marrow-derived macrophage (BMDM) memory after house dust mite (HDM) challenge. CATT7 BMDMs demonstrated a significant primed increase in M1 markers following HDM and LPS stimulation, compared to naive mice. This M1 signature was found to be MIF-dependent, as administration of a small molecule MIF inhibitor, SCD-19, blocked the induction of this pro-inflammatory M1-like phenotype in BMDMs from CATT7 mice challenged with HDM. Training naive BMDMs in vitro with HDM for 24 h followed by a rest period and subsequent stimulation with LPS led to significantly increased production of the pro-inflammatory cytokine TNFα in BMDMs from CATT7 mice but not WT mice. Addition of the pan methyltransferase inhibitor MTA before HDM training significantly abrogated this effect in BMDMs from CATT7 mice, suggesting that HDM-induced training is associated with epigenetic remodelling. These findings suggest that trained immunity induced by HDM is under genetic control, playing an important role in asthma patients with the high MIF genotypes (CATT6/7/8).

The Role of Macrophage Migration Inhibitory Factor (MIF) and D-Dopachrome Tautomerase (D-DT/MIF-2) in Infections: A Clinical Perspective

Macrophage migration inhibitory factor (MIF) and its homolog, D-dopachrome tautomerase (D-DT), are cytokines that play critical roles in the immune response to various infectious diseases. This review provides an overview of the complex involvement of MIF and D-DT in bacterial, viral, fungal, and parasitic infections. The role of MIF in different types of infections is controversial, as it has either a protective function or a host damage-enhancing function depending on the pathogen. Depending on the specific role of MIF, different therapeutic options for MIF-targeting drugs arise. Human MIF-neutralizing antibodies, anti-parasite MIF antibodies, small molecule MIF inhibitors or MIF-blocking peptides, as well as the administration of exogenous MIF or MIF activity-augmenting small molecules have potential therapeutic applications and need to be further explored in the future. In addition, MIF has been shown to be a potential biomarker and therapeutic target in sepsis. Further research is needed to unravel the complexity of MIF and D-DT in infectious diseases and to develop personalized therapeutic approaches targeting these cytokines. Overall, a comprehensive understanding of the role of MIF and D-DT in infections could lead to new strategies for the diagnosis, treatment, and management of infectious diseases.

Human macrophage migration inhibitory factor potentiates mesenchymal stromal cell efficacy in a clinically relevant model of allergic asthma

Current asthma therapies focus on reducing symptoms but fail to restore existing structural damage. Mesenchymal stromal cell (MSC) administration can ameliorate airway inflammation and reverse airway remodeling. However, differences in patient disease microenvironments seem to influence MSC therapeutic effects. A polymorphic CATT tetranucleotide repeat at position 794 of the human macrophage migration inhibitory factor (hMIF) gene has been associated with increased susceptibility to and severity of asthma. We investigated the efficacy of human MSCs in high- vs. low-hMIF environments and the impact of MIF pre-licensing of MSCs using humanized MIF mice in a clinically relevant house dust mite (HDM) model of allergic asthma. MSCs significantly attenuated airway inflammation and airway remodeling in high-MIF-expressing CATT7 mice but not in CATT5 or wild-type littermates. Differences in efficacy were correlated with increased MSC retention in the lungs of CATT7 mice. MIF licensing potentiated MSC anti-inflammatory effects at a previously ineffective dose. Mechanistically, MIF binding to CD74 expressed on MSCs leads to upregulation of cyclooxygenase 2 (COX-2) expression. Blockade of CD74 or COX-2 function in MSCs prior to administration attenuated the efficacy of MIF-licensed MSCs in vivo. These findings suggest that MSC administration may be more efficacious in severe asthma patients with high MIF genotypes (CATT6/7/8).

MIF is a common genetic determinant of COVID-19 symptomatic infection and severity

BACKGROUND

Genetic predisposition to coronavirus disease 2019 (COVID-19) may contribute to its morbidity and mortality. Because cytokines play an important role in multiple phases of infection, we examined whether commonly occurring, functional polymorphisms in macrophage migration inhibitory factor (MIF) are associated with COVID-19 infection or disease severity.

AIM

To determine associations of common functional polymorphisms in MIF with symptomatic COVID-19 or its severity.

METHODS

This retrospective case-control study utilized 1171 patients with COVID-19 from three tertiary medical centers in the USA, Hungary and Spain, together with a group of 637 pre-pandemic, healthy control subjects. Functional MIF promoter alleles (-794 CATT5-8,rs5844572), serum MIF and soluble MIF receptor levels, and available clinical characteristics were measured and correlated with COVID-19 diagnosis and hospitalization. Experimental mice genetically engineered to express human high- or low-expression MIF alleles were studied for response to coronavirus infection.

RESULTS

In patients with COVID-19, there was a lower frequency of the high-expression MIF CATT7 allele when compared to healthy controls [11% vs. 19%, odds ratio (OR) 0.54 [0.41-0.72], P < 0.0001]. Among inpatients with COVID-19 (n = 805), there was a higher frequency of the MIF CATT7 allele compared to outpatients (n = 187) (12% vs. 5%, OR 2.87 [1.42-5.78], P = 0.002). Inpatients presented with higher serum MIF levels when compared to outpatients or uninfected healthy controls (87 ng/ml vs. 35 ng/ml vs. 29 ng/ml, P < 0.001, respectively). Among inpatients, circulating MIF concentrations correlated with admission ferritin (r = 0.19, P = 0.01) and maximum CRP (r = 0.16, P = 0.03) levels. Mice with a human high-expression MIF allele showed more severe disease than those with a low-expression MIF allele.

CONCLUSIONS

In this multinational retrospective study of 1171 subjects with COVID-19, the commonly occurring -794 CATT7MIF allele is associated with reduced susceptibility to symptomatic SARS-CoV-2 infection but increased disease progression as assessed by hospitalization. These findings affirm the importance of the high-expression CATT7MIF allele, which occurs in 19% of the population, in different stages of COVID-19 infection.

Streptococcus pneumoniae meningitis and the CNS barriers

Streptococcus pneumoniae (SPN) is a globally significant cause of meningitis, the pathophysiology of which involves damage to the brain by both bacterial virulence factors and the host inflammatory response. In most cases of SPN meningitis bacteria translocate from the blood into the central nervous system (CNS). The principal site of SPN translocation into the CNS is not known, with possible portals of entry proposed to be the cerebral or meningeal blood vessels or the choroid plexus. All require SPN to bind to and translocate across the vascular endothelial barrier, and subsequently the basement membrane and perivascular structures, including an additional epithelial barrier in the case of the blood-CSF barrier. The presence of SPN in the CNS is highly inflammatory resulting in marked neutrophilic infiltration. The secretion of toxic inflammatory mediators by activated neutrophils within the CNS damages pathogen and host alike, including the non-replicative neurons which drives morbidity and mortality. As with the translocation of SPN, the recruitment of neutrophils into the CNS in SPN meningitis necessitates the translocation of neutrophils from the circulation across the vascular barrier, a process that is tightly regulated under basal conditions - a feature of the 'immune specialization' of the CNS. The brain barriers are therefore central to SPN meningitis, both through a failure to exclude bacteria and maintain CNS sterility, and subsequently through the active recruitment and/or failure to exclude circulating leukocytes. The interactions of SPN with these barriers, barrier inflammatory responses, along with their therapeutic implications, are explored in this review.

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.

Modes of action and diagnostic value of miRNAs in sepsis

Sepsis is a clinical syndrome defined as a dysregulated host response to infection resulting in life-threatening organ dysfunction. Sepsis is a major public health concern associated with one in five deaths worldwide. Sepsis is characterized by unbalanced inflammation and profound and sustained immunosuppression, increasing patient susceptibility to secondary infections and mortality. microRNAs (miRNAs) play a central role in the control of many biological processes, and deregulation of their expression has been linked to the development of oncological, cardiovascular, neurodegenerative and metabolic diseases. In this review, we discuss the role of miRNAs in sepsis pathophysiology. Overall, miRNAs are seen as promising biomarkers, and it has been proposed to develop miRNA-based therapies for sepsis. Yet, the picture is not so straightforward because of the versatile and dynamic features of miRNAs. Clearly, more research is needed to clarify the expression and role of miRNAs in sepsis, and to promote the use of miRNAs for sepsis management.

The Role of MIF and IL-10 as Molecular Yin-Yang in the Modulation of the Host Immune Microenvironment During Infections: African Trypanosome Infections as a Paradigm

African trypanosomes are extracellular flagellated unicellular protozoan parasites transmitted by tsetse flies and causing Sleeping Sickness disease in humans and Nagana disease in cattle and other livestock. These diseases are usually characterized by the development of a fatal chronic inflammatory disease if left untreated. During African trypanosome infection and many other infectious diseases, the immune response is mediating a see-saw balance between effective/protective immunity and excessive infection-induced inflammation that can cause collateral tissue damage. African trypanosomes are known to trigger a strong type I pro-inflammatory response, which contributes to peak parasitaemia control, but this can culminate into the development of immunopathologies, such as anaemia and liver injury, if not tightly controlled. In this context, the macrophage migration inhibitory factor (MIF) and the interleukin-10 (IL-10) cytokines may operate as a molecular “Yin-Yang” in the modulation of the host immune microenvironment during African trypanosome infection, and possibly other infectious diseases. MIF is a pleiotropic pro-inflammatory cytokine and critical upstream mediator of immune and inflammatory responses, associated with exaggerated inflammation and immunopathology. For example, it plays a crucial role in the pro-inflammatory response against African trypanosomes and other pathogens, thereby promoting the development of immunopathologies. On the other hand, IL-10 is an anti-inflammatory cytokine, acting as a master regulator of inflammation during both African trypanosomiasis and other diseases. IL-10 is crucial to counteract the strong MIF-induced pro-inflammatory response, leading to pathology control. Hence, novel strategies capable of blocking MIF and/or promoting IL-10 receptor signaling pathways, could potentially be used as therapy to counteract immunopathology development during African trypanosome infection, as well as during other infectious conditions. Together, this review aims at summarizing the current knowledge on the opposite immunopathological molecular “Yin-Yang” switch roles of MIF and IL-10 in the modulation of the host immune microenvironment during infection, and more particularly during African trypanosomiasis as a paradigm.

MIF but not MIF-2 recruits inflammatory macrophages in an experimental polymicrobial sepsis model

Excessive inflammation drives the progression from sepsis to septic shock. Macrophage migration inhibitory factor (MIF) is of interest because MIF promoter polymorphisms predict mortality in different infections, and anti-MIF antibody improves survival in experimental models when administered 8 hours after infectious insult. The recent description of a second MIF superfamily member, D-dopachrome tautomerase (D-DT/MIF-2), prompted closer investigation of MIF-dependent responses. We subjected Mif-/- and Mif-2-/- mice to polymicrobial sepsis and observed a survival benefit with Mif but not Mif-2 deficiency. Survival was associated with reduced numbers of small peritoneal macrophages (SPMs) that, in contrast to large peritoneal macrophages (LPMs), were recruited into the peritoneal cavity. LPMs produced higher quantities of MIF than SPMs, but SPMs expressed higher levels of inflammatory cytokines and the MIF receptors CD74 and CXCR2. Adoptive transfer of WT SPMs into Mif-/- hosts reduced the protective effect of Mif deficiency in polymicrobial sepsis. Notably, MIF-2 lacks the pseudo-(E)LR motif present in MIF that mediates CXCR2 engagement and SPM migration, supporting a specific role for MIF in the recruitment and accumulation of inflammatory SPMs.

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.

Community-acquired bacterial meningitis

Progress has been made in the prevention and treatment of community-acquired bacterial meningitis during the past three decades but the burden of the disease remains high globally. Conjugate vaccines against the three most common causative pathogens (Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae) have reduced the incidence of disease, but with the replacement by non-vaccine pneumococcal serotypes and the emergence of bacterial strains with reduced susceptibility to antimicrobial treatment, meningitis continues to pose a major health challenge worldwide. In patients presenting with bacterial meningitis, typical clinical characteristics (such as the classic triad of neck stiffness, fever, and an altered mental status) might be absent and cerebrospinal fluid examination for biochemistry, microscopy, culture, and PCR to identify bacterial DNA are essential for the diagnosis. Multiplex PCR point-of-care panels in cerebrospinal fluid show promise in accelerating the diagnosis, but diagnostic accuracy studies to justify routine implementation are scarce and randomised, controlled studies are absent. Early administration of antimicrobial treatment (within 1 hour of presentation) improves outcomes and needs to be adjusted according to local emergence of drug resistance. Adjunctive dexamethasone treatment has proven efficacy beyond the neonatal age but only in patients from high-income countries. Further progress can be expected from implementing preventive measures, especially the development of new vaccines, implementation of hospital protocols aimed at early treatment, and new treatments targeting checkpoints of the inflammatory cascade.

Macrophage migration inhibitory factor promotes the migration of dendritic cells through CD74 and the activation of the Src/PI3K/myosin II pathway

Constitutively expressed by innate immune cells, the cytokine macrophage migration inhibitory factor (MIF) initiates host immune responses and drives pathogenic responses in infectious, inflammatory, and autoimmune diseases. Dendritic cells (DCs) express high levels of MIF, but the role of MIF in DC function remains poorly characterized. As migration is critical for DC immune surveillance, we investigated whether MIF promoted the migration of DCs. In classical transwell experiments, MIF^-/- bone marrow-derived DCs (BMDCs) or MIF^+/+ BMDCs treated with ISO-1, an inhibitor of MIF, showed markedly reduced spontaneous migration and chemotaxis. CD74^-/- BMDCs that are deficient in the ligand-binding component of the cognate MIF receptor exhibited a migration defect similar to that of MIF^-/- BMDCs. Adoptive transfer experiments of LPS-matured MIF^+/+ and MIF^-/- and of CD74^+/+ and CD74^-/- BMDCs injected into the hind footpads of homologous or heterologous mice showed that the autocrine and paracrine MIF activity acting via CD74 contributed to the recruitment of DCs to the draining lymph nodes. Mechanistically, MIF activated the Src/PI3K signaling pathway and myosin II complexes, which were required for the migration of BMDCs. Altogether, these data show that the cytokine MIF exerts chemokine-like activity for DC motility and trafficking.

Macrophage-derived cytokines in pneumonia: Linking cellular immunology and genetics

Macrophages represent the first line of anti-pathogen defense - they encounter invading pathogens to perform the phagocytic activity, to deliver the plethora of pro- and anti-inflammatory cytokines, and to shape the tissue microenvironment. Throughout pneumonia course, alveolar macrophages and infiltrated blood monocytes produce increasing cytokine amounts, which activates the antiviral/antibacterial immunity but can also provoke the risk of the so-called cytokine "storm" and normal tissue damage. Subsequently, the question of how the cytokine spectrum is shaped and balanced in the pneumonia context remains a hot topic in medical immunology, particularly in the COVID19 pandemic era. The diversity in cytokine profiles, involved in pneumonia pathogenesis, is determined by the variations in cytokine-receptor interactions, which may lead to severe cytokine storm and functional decline of particular tissues and organs, for example, cardiovascular and respiratory systems. Cytokines and their receptors form unique profiles in individual patients, depending on the (a) microenvironmental context (comorbidities and associated treatment), (b) lung monocyte heterogeneity, and (c) genetic variations. These multidisciplinary strategies can be proactively considered beforehand and during the pneumonia course and potentially allow the new age of personalized immunotherapy.

ICBP90 Regulates MIF Expression, Glucocorticoid Sensitivity, and Apoptosis at the MIF Immune Susceptibility Locus

OBJECTIVE

Macrophage migration inhibitory factor (MIF) is an inflammatory and neurorendocrine mediator that counterregulates glucocorticoid immunosuppression. MIF polymorphisms, which comprise a variant promoter microsatellite (-794 CATT_5-8 ), are linked genetically to autoimmune disease severity and to glucocorticoid resistance. While invasive stimuli increase MIF expression, MIF also is up-regulated by glucocorticoids, which serve as a physiologic regulator of inflammatory responses. This study was undertaken to define interactions between the MIF promoter, the glucocorticoid receptor (GR), and the transcription factor inverted CCAAT box binding protein 90 kd (ICBP90) (also referred to as UHRF1), which binds to the promoter in a -794 CATT_5-8 length-dependent manner, to regulate MIF transcription.

METHODS

Interactions of ICBP90, GR, and activator protein 1 (AP-1) with MIF -794 CATT_5-8 promoter constructs were assessed by coimmunoprecipitation, Western blotting, and genetic knockdown. Nuclear colocalization studies were performed using anti-transcription factor antibodies and confocal microscopy of glucocorticoid-treated cells. MIF transcription was studied in CEM-C7 T cells, and the impact of the MIF -794 CATT_5-8 microsatellite variation confirmed in peripheral blood T cells and in rheumatoid synovial fibroblasts of defined MIF genotype. Functional interactions were quantified by apoptosis and apoptotic signaling in high- and low-genotypic MIF-expressing human cells.

RESULTS

We defined functional interactions between the transcription factors ICBP90, the GR, and AP-1 that up-regulated MIF transcription in a -794 CATT_5-8 length-dependent manner. Experimental reduction of ICBP90, GR, or AP-1 decreased MIF expression and increased glucocorticoid sensitivity, leading to enhanced apoptosis in T lymphocytes and in rheumatoid synovial fibroblasts.

CONCLUSION

These findings suggest a mechanism for genetic variation of glucocorticoid-regulated MIF transcription, with implications for autoimmune disease severity and glucocorticoid responsiveness.

Trained Immunity Confers Broad-Spectrum Protection Against Bacterial Infections

Background

The innate immune system recalls a challenge to adapt to a secondary challenge, a phenomenon called trained immunity. Training involves cellular metabolic, epigenetic and functional reprogramming, but how broadly trained immunity protects from infections is unknown. For the first time, we addressed whether trained immunity provides protection in a large panel of preclinical models of infections.

Methods

Mice were trained and subjected to systemic infections, peritonitis, enteritis, and pneumonia induced by Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Citrobacter rodentium, and Pseudomonas aeruginosa. Bacteria, cytokines, leukocytes, and hematopoietic precursors were quantified in blood, bone marrow, and organs. The role of monocytes/macrophages, granulocytes, and interleukin 1 signaling was investigated using depletion or blocking approaches.

Results

Induction of trained immunity protected mice in all preclinical models, including when training and infection were initiated in distant organs. Trained immunity increased bone marrow hematopoietic progenitors, blood Ly6C^high inflammatory monocytes and granulocytes, and sustained blood antimicrobial responses. Monocytes/macrophages and interleukin 1 signaling were required to protect trained mice from listeriosis. Trained mice were efficiently protected from peritonitis and listeriosis for up to 5 weeks.

Conclusions

Trained immunity confers broad-spectrum protection against lethal bacterial infections. These observations support the development of trained immunity-based strategies to improve host defenses.

The chemotactic cytokines in the cerebrospinal fluid of patients with neuroborreliosis

BACKGROUND

The outcome of neuroborreliosis (NB) is variable and may partially depend on host-related immune factors. In NB, the cerebrospinal fluid (CSF) contains a large population of T lymphocytes, but the mechanisms and consequences of their recruitment have not been fully elucidated. We have studied expression of T lymphocyte chemoattractant cytokines in association with CSF cytometric parameters and clinical data in NB patients.

METHODS

The blood and CSF of 17 patients with NB and blood of 12 patients with erythema migrans (EM) were obtained before the antibiotic administration, and in fraction of NB patients during and/or after antibiotic treatment. The control samples came from blood donors (blood) and patients in whom neuroinfection was excluded by a lumbar puncture (CSF). Concentrations of IL-16, CXCL9, CXCL10, CXCL11, CCL2 and CCL5 in serum and CSF were measured with commercial ELISA. Data were analyzed with non-parametric tests, p < 0.05 considered significant.

RESULTS

The serum concentrations of IL-16, CXCL9, CXCL10 and CCL5 were increased, higher in NB than in EM. In CSF all the cytokines were upregulated, CXCL10, CXCL9 and IL-16 over ten-fold. The CSF concentration index favored the intrathecal synthesis of all the cytokines except CCL5, for which it could not be reliably estimated. CCL2, CXCL10 and CXCL9 created concentration gradients towards CSF. The intrathecal expression of IL-16, CCL5 and CXCL9 correlated with CSF lymphocyte counts, of IL-16, CXCL9 and CXCL10 - with a blood-brain barrier disruption, and of CXCL9 and CXCL10 with intrathecal specific IgG synthesis. The expression of CCL2, CXCL10 and CXCL11 peaked early after NB onset and decreased naturally afterwards. High initial CSF CXCL9, CXCL10 and CXCL11 levels associated with a persistent CSF pleocytosis and BBB disruption after treatment, but no cytokine was predictive of clinical outcome. In follow up (post-treatment) examinations, CSF CXCL10 and CCL5 associated positively and CCL2 negatively with a protracted lymphocytic pleocytosis.

CONCLUSIONS

Several cytokines chemotactic for T lymphocytes are upregulated intrathecally in NB, with different dynamics and relation to other inflammatory parameters, suggesting their distinct pathogenetic roles. CXCL10 and CXCL9 are vividly upregulated and seem deeply involved in the pathogenesis of the intrathecal inflammation. IL-16 and CCL5 may directly drive T lymphocyte migration from periphery, but their ability to create an adequate chemotactic gradient remains to be confirmed. A delayed normalization of pleocytosis is accompanied by higher intrathecal expression of Th1-related and lower of Th2-related chemokines, in agreement with the protective role of Th1 to Th2 transition in the course of NB.

Individual responsiveness of macrophage migration inhibitory factor predicts long-term cognitive impairment after bacterial meningitis

Background

Patients with pneumococcal meningitis are at risk for death and neurological sequelae including cognitive impairment. Functional genetic polymorphisms of macrophage migration inhibitory factor (MIF) alleles have shown to predict mortality of pneumococcal meningitis.

Methods

We investigated whether MIF concentrations during the acute phase of disease were predictive for death in a nationwide prospective cohort study. Subsequently, we studied whether individual ex vivo MIF response years after meningitis was associated with the development of cognitive impairment.

Results

We found that in the acute illness of pneumococcal meningitis, higher plasma MIF concentrations were predictive for mortality (p = 0.009). Cognitive impairment, examined 1–5 years after meningitis, was present in 11 of 79 patients after pneumococcal meningitis (14%), as compared to 1 of 63 (2%) in controls, and was consistently associated with individual variability in MIF production by peripheral blood mononuclear cells after ex vivo stimulation with various infectious stimuli.

Conclusions

Our study confirms the role of MIF in poor disease outcome of pneumococcal meningitis. Inter-individual differences in MIF production were associated with long-term cognitive impairment years after pneumococcal meningitis. The present study provides evidence that MIF mediates long-term cognitive impairment in bacterial meningitis survivors and suggests a potential role for MIF as a target of immune-modulating adjunctive therapy.

The search for novel treatment strategies for Streptococcus pneumoniae infections

This review provides an overview of the most important novel treatment strategies against Streptococcus pneumoniae infections published over the past 10 years. The pneumococcus causes the majority of community-acquired bacterial pneumonia cases, and it is one of the prime pathogens in bacterial meningitis. Over the last 10 years, extensive research has been conducted to prevent severe pneumococcal infections, with a major focus on (i) boosting the host immune system and (ii) discovering novel antibacterials. Boosting the immune system can be done in two ways, either by actively modulating host immunity, mostly through administration of selective antibodies, or by interfering with pneumococcal virulence factors, thereby supporting the host immune system to effectively overcome an infection. While several of such experimental therapies are promising, few have evolved to clinical trials. The discovery of novel antibacterials is hampered by the high research and development costs versus the relatively low revenues for the pharmaceutical industry. Nevertheless, novel enzymatic assays and target-based drug design, allow the identification of targets and the development of novel molecules to effectively treat this life-threatening pathogen.

The role of host genetics in the immune response to SARS-CoV-2 and COVID-19 susceptibility and severity

This article provides a review of studies evaluating the role of host (and viral) genetics (including variation in HLA genes) in the immune response to coronaviruses, as well as the clinical outcome of coronavirus-mediated disease. The initial sections focus on seasonal coronaviruses, SARS-CoV, and MERS-CoV. We then examine the state of the knowledge regarding genetic polymorphisms and SARS-CoV-2 and COVID-19. The article concludes by discussing research areas with current knowledge gaps and proposes several avenues for future scientific exploration in order to develop new insights into the immunology of SARS-CoV-2.

The Role of MIF-173G/C Gene Polymorphism in the Susceptibility of Autoimmune Diseases

Some certain genetic polymorphisms have been considered to implicate in the pathogenesis and progression of autoimmune diseases and may predispose to an early stage of general autoimmune susceptibility. Recent studies have been conducted to investigate the association between macrophage migration inhibitory factor- (MIF-) 173G/C gene polymorphism and autoimmune diseases; however, the results were not exactly identical. In the present study, a systematic review and meta-analysis of case-control studies was performed to estimate the relationship. A comprehensive search of PubMed, Ebsco, EMbase, WanFang databases and CNKI was done. Odds ratio (ORs) and corresponding 95% confidence intervals (CIs) were combined to pool the effect size. The publication bias was examined by Begg's funnel plots and Egger's test. RevMan 5.3 and STATA 12.0 software were used for statistical processing. 23 papers were included, and the results revealed that MIF-173G/C was significantly associated with an increased risk of autoimmune diseases in five genetic models (recessive genetic model: OR = 1.95, 95% CI: 1.52-2.50; dominant genetic model: OR = 1.35, 95% CI: 1.24-1.46; allele model: OR = 1.32, 95% CI: 1.23-1.41; homozygote model: OR = 1.92, 95% CI: 1.57-2.35; heterozygote model: OR = 4.92, 95% CI: 4.03-6.02), whether in Asia, Europe, or North America. Furthermore, subgroup analysis showed an increasing risk in rheumatoid arthritis (RA), ulcerative colitis (UC), Crohn's disease (CD), atopic dermatitis (AD), Henoch-Schonlein purpura (HSP), and Henoch-Schonlein purpura nephritis (HSPN), but it was not related to the susceptibility of autoimmune hepatitis (AIH). Therefore, it could be considered that MIF-173G/C polymorphism could increase the susceptibility of autoimmune diseases, while there may be the discrepancy of disease entity.

Quality Control Measures and Validation in Gene Association Studies: Lessons for Acute Illness

Acute illness is a complex constellation of responses involving dysregulated inflammatory and immune responses, which are ultimately associated with multiple organ dysfunction. Gene association studies have associated single-nucleotide polymorphisms (SNPs) with clinical and pharmacological outcomes in a variety of disease states, including acute illness. With approximately 4 to 5 million SNPs in the human genome and recent studies suggesting that a large portion of SNP studies are not reproducible, we suggest that the ultimate clinical utility of SNPs in acute illness depends on validation and quality control measures. To investigate this issue, in December 2018 and January 2019 we searched the literature for peer-reviewed studies reporting data on associations between SNPs and clinical outcomes and between SNPs and pharmaceuticals (i.e., pharmacogenomics) published between January 2011 to February 2019. We review key methodologies and results from a variety of clinical and pharmacological gene association studies, including trauma and sepsis studies, as illustrative examples on current SNP association studies. In this review article, we have found three key points which strengthen the potential accuracy of SNP association studies in acute illness and other diseases: providing evidence of following a protocol quality control method such as the one in Nature Protocols or the OncoArray QC Guidelines; enrolling enough patients to have large cohort groups; and validating the SNPs using an independent technique such as a second study using the same SNPs with new patient cohorts. Our survey suggests the need to standardize validation methods and SNP quality control measures in medicine in general, and specifically in the context of complex disease states such as acute illness.

Dual Deletion of the Sirtuins SIRT2 and SIRT3 Impacts on Metabolism and Inflammatory Responses of Macrophages and Protects From Endotoxemia

Sirtuin 2 (SIRT2) and SIRT3 are cytoplasmic and mitochondrial NAD-dependent deacetylases. SIRT2 and SIRT3 target proteins involved in metabolic, proliferation and inflammation pathways and have been implicated in the pathogenesis of neurodegenerative, metabolic and oncologic disorders. Both pro- and anti-inflammatory effects have been attributed to SIRT2 and SIRT3, and single deficiency in SIRT2 or SIRT3 had minor or no impact on antimicrobial innate immune responses. Here, we generated a SIRT2/3 double deficient mouse line to study the interactions between SIRT2 and SIRT3. SIRT2/3^−/− mice developed normally and showed subtle alterations of immune cell populations in the bone marrow, thymus, spleen, blood and peritoneal cavity that contained notably more anti-inflammatory B-1a cells and less NK cells. In vitro, SIRT2/3^−/− macrophages favored fatty acid oxidation (FAO) over glycolysis and produced increased levels of both proinflammatory and anti-inflammatory cytokines. In line with metabolic adaptation and increased numbers of peritoneal B-1a cells, SIRT2/3^−/− mice were robustly protected from endotoxemia. Yet, SIRT2/3 double deficiency did not modify endotoxin tolerance. Overall, these data suggest that sirtuins can act in concert or compensate each other for certain immune functions, a parameter to be considered for drug development. Moreover, inhibitors targeting multiple sirtuins developed for clinical purposes may be useful to treat inflammatory diseases.

Host genetic variability and pneumococcal disease: a systematic review and meta-analysis

Background

Pneumonia, sepsis, meningitis, and empyema due to Streptococcus pneumoniae is a major cause of morbidity and mortality. We provide a systemic overview of genetic variants associated with susceptibility, phenotype and outcome of community acquired pneumococcal pneumonia (CAP) and invasive pneumococcal disease (IPD).

Methods

We searched PubMed for studies on the influence of host genetics on susceptibility, phenotype, and outcome of CAP and IPD between Jan 1, 1983 and Jul 4, 2018. We listed methodological characteristics and when genetic data was available we calculated effect sizes. We used fixed or random effect models to calculate pooled effect sizes in the meta-analysis.

Results

We identified 1219 studies of which 60 studies involving 15,358 patients were included. Twenty-five studies (42%) focused on susceptibility, 8 (13%) on outcome, 1 (2%) on disease phenotype, and 26 (43%) on multiple categories. We identified five studies with a hypothesis free approach of which one resulted in one genome wide significant association in a gene coding for lincRNA with pneumococcal disease susceptibility. We performed 17 meta-analyses of which two susceptibility polymorphisms had a significant overall effect size: variant alleles of MBL2 (odds ratio [OR] 1·67, 95% confidence interval [CI] 1·04–2·69) and a variant in CD14 (OR 1·77, 95% CI 1·18–2·66) and none of the outcome polymorphisms.

Conclusions

Studies have identified several host genetics factors influencing risk of pneumococcal disease, but many result in non-reproducible findings due to methodological limitations. Uniform case definitions and pooling of data is necessary to obtain more robust findings.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0572-x) contains supplementary material, which is available to authorized users.

Macrophage migration inhibitory factor (MIF) as a therapeutic target for rheumatoid arthritis and systemic lupus erythematosus

Introduction. Macrophage migration inhibitory factor (MIF) is a pleiotropic inflammatory cytokine with upstream regulatory roles in innate and adaptive immunity and is implicated in the pathogenesis of autoimmune diseases including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Several classes of MIF inhibitors such as small molecule inhibitors and peptide inhibitors are in clinical development. Areas covered. The role of MIF in the pathogenesis of RA and SLE is examined; the authors review the structure, physiology and signaling characteristics of MIF and the related cytokine D-DT/MIF-2. The preclinical and clinical trial data for MIF inhibitors are also reviewed; information was retrieved from PubMed and ClinicalTrials.gov using the keywords MIF, D-DT/MIF-2, CD74, CD44, CXCR2, CXCR4, Jab-1, rheumatoid arthritis, systemic lupus erythematosus, MIF inhibitor, small molecule, anti-MIF, anti-CD74, and peptide inhibitor. Expert opinion. Studies in mice and in humans demonstrate the therapeutic potential of MIF inhibition for RA and SLE. MIF- directed approaches could be particularly efficacious in patients with high expression MIF genetic polymorphisms. In patients with RA and SLE and high expression MIF alleles, targeted MIF inhibition could be a precision medicine approach to treatment. Anti-MIF pharmacotherapies could also be steroid-sparing in patients with chronic glucocorticoid dependence or refractory autoimmune disease.

Novel and preclinical treatment strategies in pneumococcal meningitis

PURPOSE OF REVIEW

Pneumococcal meningitis is the most frequent form of bacterial meningitis in Europe and the United States. Although early antimicrobial and adjuvant therapy with dexamethasone have helped to improve disease outcome in adults, mortality and morbidity rates remain unsatisfactorily high, emphasizing the need for additional treatment options. Promising targets for adjuvant therapy have been identified recently and will be the focus of this review.

RECENT FINDINGS

Brain disease in pneumococcal meningitis is caused by direct bacterial toxicity and excessive meningeal inflammation. Accordingly, promising targets for adjuvant therapy comprise limiting the release of toxic bacterial products and suppressing inflammation in a way that maximally protects against tissue injury without hampering pathogen eradication by antibiotics. Among the agents tested so far in experimental models, complement inhibitors, matrix-metalloproteinase inhibitors, and nonbacteriolytic antibiotics or a combination of the above have the potential to more efficiently protect the brain either alone (e.g., in children and outside the high-income settings) or in addition to adjuvant dexamethasone. Additionally, new protein-based pneumococcal vaccines are being developed that promise to improve disease prevention, namely by addressing the increasing problem of serotype replacement seen with pneumococcal conjugate vaccines.

SUMMARY

Pneumococcal meningitis remains a life-threatening disease requiring early antibiotic and targeted anti-inflammatory therapy. New adjuvant therapies showed promising results in animal models but need systematic clinical testing.

Macrophage migration inhibitory factor enhances influenza-associated mortality in mice

Influenza-associated mortality continues to occur annually despite available antiviral therapies. New therapies that improve host immunity could reduce influenza virus disease burden. Targeting macrophage migration inhibitory factor (MIF) has improved the outcomes of certain inflammatory diseases, but its role in influenza viral infection is unclear. Here, we showed that, during influenza viral infection, Mif-deficient mice have less inflammation, viral load, and mortality compared with WT control mice; conversely, Tg mice, overexpressing Mif in alveolar epithelial cells, had higher inflammation, viral load, and mortality. Antibody-mediated blockade of MIF in WT mice during influenza viral infection improved their survival. Mif-deficient murine lungs showed reduced levels of parkin, a mitophagy protein that negatively regulates antiviral signaling, prior to infection and augmented antiviral type I/III IFN levels in the airspaces after infection as compared with WT lungs. Additionally, in vitro assays with human lung epithelial cells showed that treatment with recombinant human MIF increased the percentage of influenza virus-infected cells. In conclusion, our study reveals that MIF impairs antiviral host immunity and increases inflammation during influenza infection and suggests that targeting MIF could be therapeutically beneficial during influenza viral infection.

Fulminant arterial vasculitis as an unusual complication of disseminated staphylococcal disease due to the emerging CC1 methicillin-susceptible Staphylococcus aureus clone: a case report

BACKGROUND

Staphylococcus aureus has emerged as a leading cause of invasive severe diseases with a high rate of morbidity and mortality worldwide. The wide spectrum of clinical manifestations and outcome observed in staphylococcal illness may be a consequence of both microbial factors and variability of the host immune response.

CASE PRESENTATION

A 14-years old child developed limb ischemia with gangrene following S. aureus bloodstream infection. Histopathology revealed medium-sized arterial vasculitis. The causing strain belonged to the emerging clone CC1-MSSA and numerous pathogenesis-related genes were identified. Patient's genotyping revealed functional variants associated with severe infections. A combination of virulence and host factors might explain this unique severe form of staphylococcal disease.

CONCLUSION

A combination of virulence and genetic host factors might explain this unique severe form of staphylococcal disease.

Macrophage migration inhibitory factor regulates innate γδ T-cell responses via IL-17 expression

T cells expressing invariant γδ antigen receptors (γδ T cells) bridge innate and adaptive immunity and facilitate barrier responses to pathogens. Macrophage migration inhibitory factor (MIF) is an upstream mediator of host defense that up-regulates the expression of pattern recognition receptors and sustains inflammatory responses by inhibiting activation-induced apoptosis in monocytes and macrophages. Surprisingly, Mif^-/- γδ T cells, when compared with wild type, were observed to produce >10-fold higher levels of the proinflammatory cytokine IL-17 after stimulation with gram-positive exotoxins. High-IL-17 expression was associated with the characteristic features of IL-17-producing γδ T (γδ17) cells, including expression of IL-23R, IL-1R1, and the transcription factors RORγt and Sox13. In the gram-positive model of shock mediated by toxic shock syndrome toxin (TSST-1), Mif^-/- mice succumbed to death more quickly with increased pulmonary neutrophil accumulation and higher production of cytokines, including IL-1β and IL-23. Mif^-/- γδ T cells also produced high levels of IL-17 in response to Mycobacterium lipomannan, and depletion of γδ T cells improved survival from acutely lethal Mycobacterium infection or TSST-1 administration. These data indicate that MIF deficiency is associated with a compensatory amplification of γδ17 cell responses, with implications for innate immunity and IL-17-mediated pathology in situations such as gram-positive toxic shock or Mycobacterium infection.-Kim, H. K., Garcia, A. B., Siu, E., Tilstam, P., Das, R., Roberts, S., Leng, L., Bucala, R. Macrophage migration inhibitory factor regulates innate γδ T-cell responses via IL-17 expression.

Low expression Macrophage Migration Inhibitory Factor (MIF) alleles and tuberculosis in HIV infected South Africans

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Low expression MIF alleles are prevalent in South Africa, which has the greatest burden of TB and HIV.

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Low genotypic MIF expressers were more frequent among HIV cases with TB compared to those without TB.

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Serum MIF correlated with lower CD4 cells regardless of TB, suggesting HIV impacts MIF expression.

Host immunity is crucial for controlling M. tuberculosis infection. Functional polymorphisms in the cytokine macrophage migration inhibitory factor (MIF) show global population stratification, with the highest prevalence of low expression MIF alleles found in sub-Saharan Africans, which is a population with the greatest confluence of both TB and HIV infection and disease. We investigated the association between MIF alleles and tuberculosis (TB) and HIV in South Africa. We acquired clinical information and determined the frequency of two MIF promoter variants: a functional −794 CATT_5-8 microsatellite and an associated −173 G/C SNP in two HIV-positive cohorts of patients with active laboratory-confirmed TB and in controls without active TB who were all HIV positive. We found a greater frequency of low expression MIF promoter variants (-794 CATT_5,6) among TB disease cases compared to controls (OR = 2.03, p = 0.023), supporting a contribution of genetic low MIF expression to the high prevalence of TB in South Africa. Among those with HIV, circulating MIF levels also were associated with lower CD4 cell counts irrespective of TB status (p = 0.016), suggesting an influence of HIV immunosuppression on MIF expression.

Genetic Polymorphisms in Sepsis and Cardiovascular Disease: Do Similar Risk Genes Suggest Similar Drug Targets?

Genetic variants are associated with altered clinical outcome of patients with sepsis and cardiovascular diseases. Common gene signaling pathways may be involved in the pathophysiology of these diseases. A better understanding of genetic commonality among these diseases may enable the discovery of important genes, signaling pathways, and therapeutic targets for these diseases. We investigated the common genetic factors by a systematic search of the literature. Twenty-four genes (ADRB2, CD14, FGB, FV, HMOX1, IL1B, IL1RN, IL6, IL10, IL17A, IRAK1, MASP2, MBL, MIR608, MIF, NOD2, PCSK9, PPARG, PROC, SERPINE1, SOD2, SVEP1, TF, TIRAP, TLR1) were extracted as reported genetic variations associated with altered outcome of both sepsis and cardiovascular diseases. Of these genes, the adverse allele (or combinations) was same in nine (ADRB2, FV, HMOX1, IL6, MBL, MIF, NOD2, PCSK9, SERPINE1), and the effect appears to be in the same direction in both sepsis and cardiovascular disease. Shared gene signaling pathways suggest that these are true biological results and could point to overlapping drug targets in sepsis and cardiovascular disease.

Sirtuin 5 Deficiency Does Not Compromise Innate Immune Responses to Bacterial Infections

Sirtuin 5 (SIRT5) is a member of the family of NAD⁺-dependent lysine/histone deacetylases. SIRT5 resides mainly in the mitochondria where it catalyzes deacetylation, demalonylation, desuccinylation, and deglutarylation of lysine to regulate metabolic and oxidative stress response pathways. Pharmacologic inhibitors of SIRT5 are under development for oncologic conditions, but nothing is known about the impact of SIRT5 on antimicrobial innate immune defenses. Using SIRT5 knockout mice, we show that SIRT5 deficiency does not affect immune cell development, cytokine production and proliferation by macrophages and splenocytes exposed to microbial and immunological stimuli. Moreover, preclinical models suggest that SIRT5 deficiency does not worsen endotoxemia, Klebsiella pneumoniae and Streptococcus pneumoniae pneumonia, Escherichia coli peritonitis, listeriosis, and staphylococcal infection. Altogether, these data support the safety profile in terms of susceptibility to infections of SIRT5 inhibitors under development.

Small-molecule inhibitors of macrophage migration inhibitory factor (MIF) as an emerging class of therapeutics for immune disorders

Macrophage migration inhibitory factor (MIF) is an important cytokine for which an increasing number of functions is being described in the pathogenesis of inflammation and cancer. Nevertheless, the availability of potent and druglike MIF inhibitors that are well-characterized in relevant disease models remains limited. Development of highly potent and selective small-molecule MIF inhibitors and validation of their use in relevant disease models will advance drug discovery. In this review, we provide an overview of recent advances in the identification of MIF as a pharmacological target in the pathogenesis of inflammatory diseases and cancer. We also give an overview of the current developments in the discovery and design of small-molecule MIF inhibitors and define future aims in this field.

Increased serum levels and promoter polymorphisms of macrophage migration inhibitory factor in schizophrenia

BACKGROUND

Numerous studies have suggested that an immune system imbalance plays an important role in schizophrenia. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine. It plays multiple roles in various biological processes, including inflammation and neurogenesis. Furthermore, several exhaustive serum proteomic profiling studies have identified MIF as a potential biomarker of schizophrenia. Here, we investigate MIF protein levels in serum and postmortem prefrontal cortex in patients with schizophrenia and controls. Moreover, we investigate the association of two functional polymorphisms in the MIF gene promoter region (MIF-794CATT_5-8 microsatellite and MIF-173G/C single-nucleotide polymorphism [SNP]) with schizophrenia.

METHODS

We measured serum MIF levels with an enzyme-linked immunosorbent assay (ELISA) (51 patients vs. 86 controls) and postmortem brain MIF levels with a western blotting assay (18 patients vs. 22 controls). Subsequently, we genotyped the MIF-794CATT_5-8 microsatellite with a fluorescence-based fragment assay and the MIF-173G/C SNP with a TaqMan SNP genotyping assay (1483 patients vs. 1454 controls).

RESULTS

Serum MIF levels were significantly higher in patients with schizophrenia than in controls (p=0.00118), and were positively correlated with antipsychotic dose (Spearman's r=0.222, p=0.0402). In addition, an earlier age of onset was observed in patients with a high serum MIF level (≥40ng/mL) than those with a low serum MIF level (<40ng/mL) (p=0.0392). However, postmortem brain MIF levels did not differ between patients with schizophrenia and controls. The association study revealed that the CATT₆-G haplotype was nominally significantly associated with schizophrenia (p=0.0338), and that the CATT₆ allele and CATT₆-G haplotype were significantly associated with female adolescent-onset schizophrenia (AsOS) (corrected p=0.0222 and p=0.0147, respectively).

CONCLUSIONS

These results suggest that serum MIF level is a potential pharmacodynamic and/or monitoring marker of schizophrenia, and is related to a novel antipsychotic effect beyond dopamine antagonism. Furthermore, the MIF gene polymorphisms are associated with the risk for schizophrenia especially in adolescent females, and are potential stratification markers of schizophrenia. Further studies of MIF are warranted to elucidate the pathophysiology of schizophrenia and the effects of antipsychotics.

Novel half-life extended anti-MIF nanobodies protect against endotoxic shock

Sepsis-leading to septic shock-is the leading cause of death in intensive care units. The systemic inflammatory response to infection, which is initiated by activated myeloid cells, plays a key role in the lethal outcome. Macrophage migration inhibitory factor (MIF) is an upstream immunoregulatory mediator, released by myeloid cells, that underlies a common genetic susceptibility to different infections and septic shock. Accordingly, strategies that are aimed at inhibiting the action of MIF have therapeutic potential. Here, we report the isolation and characterization of tailorable, small, affinity-matured nanobodies (Nbs; single-domain antigen-binding fragments derived from camelid heavy-chain Abs) directed against MIF. Of importance, these bioengineered Nbs bind both human and mouse MIFs with nanomolar affinity. NbE5 and NbE10 inhibit key MIF functions that can exacerbate septic shock, such as the tautomerase activity of MIF (by blocking catalytic pocket residues that are critical for MIF's conformation and receptor binding), the TNF-inducing potential, and the ability of MIF to antagonize glucocorticoid action. A lead NbE10, tailored to be a multivalent, half-life extended construct (NbE10-NbAlb8-NbE10), attenuated lethality in murine endotoxemia when administered via single injection, either prophylactically or therapeutically. Hence, Nbs, with their structural and pharmacologic advantages over currently available inhibitors, may be an effective, novel approach to interfere with the action of MIF in septic shock and other conditions of inflammatory end-organ damage.-Sparkes, A., De Baetselier, P., Brys, L., Cabrito, I., Sterckx, Y. G.-J., Schoonooghe, S., Muyldermans, S., Raes, G., Bucala, R., Vanlandschoot, P., Van Ginderachter, J. A., Stijlemans, B. Novel half-life extended anti-MIF nanobodies protect against endotoxic shock.

New Strategies Using Antibody Combinations to Increase Cancer Treatment Effectiveness

Antibodies have proven their high value in antitumor therapy over the last two decades. They are currently being used as the first-choice to treat some of the most frequent metastatic cancers, like HER2⁺ breast cancers or colorectal cancers, currently treated with trastuzumab (Herceptin) and bevacizumab (Avastin), respectively. The impressive therapeutic success of antibodies inhibiting immune checkpoints has extended the use of therapeutic antibodies to previously unanticipated tumor types. These anti-immune checkpoint antibodies allowed the cure of patients devoid of other therapeutic options, through the recovery of the patient’s own immune response against the tumor. In this review, we describe how the antibody-based therapies will evolve, including the use of antibodies in combinations, their main characteristics, advantages, and how they could contribute to significantly increase the chances of success in cancer therapy. Indeed, novel combinations will consist of mixtures of antibodies against either different epitopes of the same molecule or different targets on the same tumor cell; bispecific or multispecific antibodies able of simultaneously binding tumor cells, immune cells or extracellular molecules; immunomodulatory antibodies; antibody-based molecules, including fusion proteins between a ligand or a receptor domain and the IgG Fab or Fc fragments; autologous or heterologous cells; and different formats of vaccines. Through complementary mechanisms of action, these combinations could contribute to elude the current limitations of a single antibody which recognizes only one particular epitope. These combinations may allow the simultaneous attack of the cancer cells by using the help of the own immune cells and exerting wider therapeutic effects, based on a more specific, fast, and robust response, trying to mimic the action of the immune system.

MIF and D-DT are potential disease severity modifiers in male MS subjects

Little is known about mechanisms that drive the development of progressive multiple sclerosis (MS), although inflammatory factors, such as macrophage migration inhibitory factor (MIF), its homolog D-dopachrome tautomerase (D-DT), and their common receptor CD74 may contribute to disease worsening. Our findings demonstrate elevated MIF and D-DT levels in males with progressive disease compared with relapsing-remitting males (RRMS) and female MS subjects, with increased levels of CD74 in females vs. males with high MS disease severity. Furthermore, increased MIF and D-DT levels in males with progressive disease were significantly correlated with the presence of two high-expression promoter polymorphisms located in the MIF gene, a -794CATT_5-8 microsatellite repeat and a -173 G/C SNP. Conversely, mice lacking MIF or D-DT developed less-severe signs of experimental autoimmune encephalomyelitis, a murine model of MS, thus implicating both homologs as copathogenic contributors. These findings indicate that genetically controlled high MIF expression (and D-DT) promotes MS progression in males, suggesting that these two factors are sex-specific disease modifiers and raising the possibility that aggressive anti-MIF treatment of clinically isolated syndrome or RRMS males with a high-expresser genotype might slow or prevent the onset of progressive MS. Additionally, selective targeting of MIF:CD74 signaling might provide an effective, trackable therapeutic approach for MS subjects of both sexes.

Sirtuin 2 Deficiency Increases Bacterial Phagocytosis by Macrophages and Protects from Chronic Staphylococcal Infection

Sirtuin 2 (SIRT2) is one of the seven members of the family of NAD⁺-dependent histone deacetylases. Sirtuins target histones and non-histone proteins according to their subcellular localization, influencing various biological processes. SIRT2 resides mainly in the cytoplasm and regulates cytoskeleton dynamics, cell cycle, and metabolic pathways. As such, SIRT2 has been implicated in the pathogenesis of neurodegenerative, metabolic, oncologic, and chronic inflammatory disorders. This motivated the development of SIRT2-directed therapies for clinical purposes. However, the impact of SIRT2 on antimicrobial host defense is largely unknown. Here, we address this question using SIRT2 knockout mice. We show that SIRT2 is the most highly expressed sirtuin in myeloid cells, especially macrophages. SIRT2 deficiency does not affect immune cell development and marginally impacts on intracellular signaling and cytokine production by splenocytes and macrophages. However, SIRT2 deficiency enhances bacterial phagocytosis by macrophages. In line with these observations, in preclinical models, SIRT2 deficiency increases survival of mice with chronic staphylococcal infection, while having no effect on the course of toxic shock syndrome toxin-1, LPS or TNF-induced shock, fulminant Escherichia coli peritonitis, sub-lethal Klebsiella pneumoniae pneumonia, and chronic candidiasis. Altogether, these data support the safety profile of SIRT2 inhibitors under clinical development in terms of susceptibility to infections.

The increased concentration of macrophage migration inhibitory factor in serum and cerebrospinal fluid of patients with tick-borne encephalitis

Background

Host factors determining the clinical presentation of tick-borne encephalitis (TBE) are not fully elucidated. The peripheral inflammatory response to TBE virus is hypothesized to facilitate its entry into central nervous system by disrupting the blood-brain barrier with the involvement of a signaling route including Toll-like receptor 3 (TLR3) and pro-inflammatory cytokines macrophage migration inhibitory factor (MIF), tumor necrosis factor-α (TNFα), and interleukin-1 beta (IL-1β).

Methods

Concentrations of MIF, TNFα, and IL-1β were measured with commercial ELISA in serum and cerebrospinal fluid (CSF) from 36 hospitalized TBE patients, 7 patients with non-TBE meningitis, and 6 controls. The CSF albumin quotient (AQ) was used as a marker of blood-brain barrier permeability. Single nucleotide polymorphisms rs3775291, rs5743305 (associated with TLR3 expression), and rs755622 (associated with MIF expression) were assessed in blood samples from 108 TBE patients and 72 non-TBE controls. The data were analyzed with non-parametric tests, and p < 0.05 was considered significant.

Results

The median serum and CSF concentrations of MIF and IL-1β were significantly increased in TBE group compared to controls. MIF concentration in serum tended to correlate with AQ in TBE, but not in non-TBE meningitis. The serum concentration of TNFα was increased in TBE patients bearing a high-expression TLR3 rs5743305 TT genotype, which also associated with the increased risk of TBE. The low-expression rs3775291 TLR3 genotype TT associated with a prolonged increase of CSF protein concentration. The high-expression MIF rs755622 genotype CC tended to correlate with an increased risk of TBE, and within TBE group, it was associated with a mild presentation.

Conclusions

The results point to the signaling route involving TLR3, MIF, and TNFα being active in TBE virus infection and contributing to the risk of an overt neuroinvasive disease. The same factors may play a protective role intrathecally contributing to the milder course of neuroinfection. This suggests that the individual variability of the risk and clinical presentation of TBE might be traced to the variable peripheral and intrathecal expression of the mediators of the inflammatory response, which in turn associates with the host genetic background.

Sirtuin 3 deficiency does not alter host defenses against bacterial and fungal infections

Sirtuin 3 (SIRT3) is the main mitochondrial deacetylase. SIRT3 regulates cell metabolism and redox homeostasis, and protects from aging and age-associated pathologies. SIRT3 may drive both oncogenic and tumor-suppressive effects. SIRT3 deficiency has been reported to promote chronic inflammation-related disorders, but whether SIRT3 impacts on innate immune responses and host defenses against infections remains essentially unknown. This aspect is of primary importance considering the great interest in developing SIRT3-targeted therapies. Using SIRT3 knockout mice, we show that SIRT3 deficiency does not affect immune cell development and microbial ligand-induced proliferation and cytokine production by splenocytes, macrophages and dendritic cells. Going well along with these observations, SIRT3 deficiency has no major impact on cytokine production, bacterial burden and survival of mice subjected to endotoxemia, Escherichia coli peritonitis, Klebsiella pneumoniae pneumonia, listeriosis and candidiasis of diverse severity. These data suggest that SIRT3 is not critical to fight infections and support the safety of SIRT3-directed therapies based on SIRT3 activators or inhibitors for treating metabolic, oncologic and neurodegenerative diseases without putting patients at risk of infection.

Plasma Levels of Macrophage Migration Inhibitory Factor and d-Dopachrome Tautomerase Show a Highly Specific Profile in Early Life

Macrophage migration inhibitory factor (MIF) is a pleiotropic, constitutively expressed, pro-inflammatory cytokine and an important regulator of immune responses. d-dopachrome tautomerase (DDT), a newly described member of the MIF protein superfamily, shares sequence homology and biological activities with MIF. We recently reported that high expression levels of MIF sustain innate immune responses in newborns. Here, we elected to further characterize age-dependent MIF expression and to define whether DDT shares a similar expression profile with MIF. Therefore, we delineated the circulating concentrations of MIF and DDT throughout life using a large cohort of 307 subjects including fetuses, newborns, infants, children, and adults. Compared to levels measured in healthy adults (median: 5.7 ng/ml for MIF and 16.8 ng/ml for DDT), MIF and DDT plasma concentrations were higher in fetuses (median: 48.9 and 29.6 ng/ml), increased further at birth (median: 82.6 and 52.0 ng/ml), reached strikingly elevated levels on postnatal day 4 (median: 109.5 and 121.6 ng/ml), and decreased to adult levels during the first months of life. A strong correlation was observed between MIF and DDT concentrations in all age groups (R = 0.91, P < 0.0001). MIF and DDT levels correlated with concentrations of vascular endothelial growth factor, a protein upregulated under low oxygen tension and implicated in vascular and lung development (R = 0.70, P < 0.0001 for MIF and R = 0.65, P < 0.0001 for DDT). In very preterm infants, lower levels of MIF and DDT on postnatal day 6 were associated with an increased risk of developing bronchopulmonary dysplasia and late-onset neonatal sepsis. Thus, MIF and DDT plasma levels show a highly specific developmental profile in early life, supporting an important role for these cytokines during the neonatal period.

Mannose-binding lectin-associated serine protease 2 (MASP-2) contributes to poor disease outcome in humans and mice with pneumococcal meningitis

Background

Pneumococcal meningitis is the most common and severe form of bacterial meningitis. Fatality rates are substantial, and long-term sequelae develop in about half of survivors. Disease outcome has been related to the severity of the pro-inflammatory response in the subarachnoid space. The complement system, which mediates key inflammatory processes, has been implicated as a modulator of pneumococcal meningitis disease severity in animal studies.

Methods

We investigated mannose-binding lectin-associated serine protease (MASP-2) levels in cerebrospinal fluid (CSF) samples derived from the diagnostic lumbar puncture, which was available for 307 of 792 pneumococcal meningitis episodes included in our prospective nationwide cohort study (39%), and the association between these levels and clinical outcome. Subsequently, we studied the role of MASP-2 in our experimental pneumococcal meningitis mouse model using Masp2^−/− mice and evaluated the potential of adjuvant treatment with MASP-2-specific monoclonal antibodies in wild-type (WT) mice.

Results

MASP-2 levels in cerebrospinal fluid of patients with bacterial meningitis were correlated with poor functional outcome. Consistent with these human data, Masp2-deficient mice with pneumococcal meningitis had lower cytokine levels and increased survival compared to WT mice. Adjuvant treatment with MASP-2-specific monoclonal antibodies led to reduced complement activation and decreased disease severity.

Conclusions

MASP-2 contributes to poor disease outcome in human and mice with pneumococcal meningitis. MASP-2-specific monoclonal antibodies can be used to attenuate the inflammatory response in pneumococcal meningitis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0770-9) contains supplementary material, which is available to authorized users.

Association study of MIF promoter polymorphisms with suicide completers in the Japanese population

BACKGROUND

Numerous studies suggest that inflammation plays a key role in suicidal behavior. Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, has received increasing attention in depression research. However, no study has investigated whether MIF has genetic involvement in completed suicide. In this study, we sought to explore the relationship between two functional polymorphisms on the MIF gene promoter (MIF-794CATT_5-8 microsatellite and MIF-173G/C single-nucleotide polymorphism [SNP]) and completed suicide by using one of the largest samples of suicide completers ever reported.

METHODS

The subjects comprised 602 suicide completers and 728 healthy controls. We genotyped MIF-794CATT_5-8 microsatellite by polymerase chain reaction-based size discrimination assay and MIF-173G/C SNP by TaqMan^® SNP genotyping assay. The allele-, genotype-, or haplotype-based association analyses between the suicide completers and the controls were carried out with the χ² test, the Cochran-Armitage trend test, or Fisher's exact test.

RESULTS

Analyses of allele or genotype frequency distributions of the polymorphisms studied here did not reveal any significant differences between the suicide completers and the controls. Haplotype analysis also revealed no association with completed suicide.

CONCLUSION

To our knowledge, this is the first study that has examined the genetic association between MIF and completed suicide. Our results suggest that the effects of MIF-794CATT_5-8 microsatellite and MIF-173G/C SNP on the MIF gene promoter might not contribute to the genetic risk of completed suicide in the Japanese population.

Impact of the microbial derived short chain fatty acid propionate on host susceptibility to bacterial and fungal infections in vivo

Short chain fatty acids (SCFAs) produced by intestinal microbes mediate anti-inflammatory effects, but whether they impact on antimicrobial host defenses remains largely unknown. This is of particular concern in light of the attractiveness of developing SCFA-mediated therapies and considering that SCFAs work as inhibitors of histone deacetylases which are known to interfere with host defenses. Here we show that propionate, one of the main SCFAs, dampens the response of innate immune cells to microbial stimulation, inhibiting cytokine and NO production by mouse or human monocytes/macrophages, splenocytes, whole blood and, less efficiently, dendritic cells. In proof of concept studies, propionate neither improved nor worsened morbidity and mortality parameters in models of endotoxemia and infections induced by gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae), gram-positive bacteria (Staphylococcus aureus, Streptococcus pneumoniae) and Candida albicans. Moreover, propionate did not impair the efficacy of passive immunization and natural immunization. Therefore, propionate has no significant impact on host susceptibility to infections and the establishment of protective anti-bacterial responses. These data support the safety of propionate-based therapies, either via direct supplementation or via the diet/microbiota, to treat non-infectious inflammation-related disorders, without increasing the risk of infection.

[Changes in blood CD4+CD25+ regulatory T cells in children with severe purulent meningitis]

OBJECTIVE

To preliminarily study the changes in CD4⁺CD25⁺ regulatory T cells (Tregs) in children with severe purulent meningitis at the early stage and its possible implications.

METHODS

A retrospective analysis was performed on the clinical data of 39 children with severe purulent meningitis who were admitted to the pediatric intensive care unit from August 2014 to December 2015. According to whether Tregs count was decreased within 12 hours of hospitalization (considering Tregs count <410/mm³ as decreased), they were divided into two groups: decrease group and non-decrease group. The associations between the changes in Tregs cells and the clinical manifestations, laboratory marker levels, and prognosis were analyzed.

RESULTS

Of the 39 cases, 13 (33%) showed a decrease in the proportion of Tregs cells (<31%) and 18 (46%) showed a decrease in the absolute Tregs cell count (<410/mm³). Four deaths were all in the Tregs decrease group. Compared with the non-decrease group, the decrease group showed a significantly higher proportion of children with a peripheral blood leukocyte count lower than the normal range and a significantly greater increase in the level of serum procalcitonin (P<0.05).

CONCLUSIONS

Tregs might be suppressed in children with severe purulent meningitis at the early stage. And its suppression could be related to the severer inflammation reaction and higher mortality in those patients.