Showing papers by "Richard Bucala published in 2016"

CD74-Downregulation of Placental Macrophage-Trophoblastic Interactions in Preeclampsia.

Abstract: Rationale: MWe hypothesized that Cluster of differentiation 74 (CD74) downregulation on placental macrophages, leading to altered macrophage-trophoblast interaction, is involved in preeclampsia. Objective: Preeclamptic pregnancies feature hypertension, proteinuria and placental anomalies. Feto-placental macrophages regulate villous trophoblast differentiation during placental development. Disturbance of this well-balanced regulation can lead to pathological pregnancies. Methods and Results: We performed whole genome expression analysis of placental tissue. CD74 was one of the most downregulated genes in placentas from preeclamptic women. By RT-PCR, we confirmed this finding in early onset (<34 gestational week, n=26) and late onset (≥34 gestational week, n=24) samples from preeclamptic women, compared to healthy pregnant controls (n=28). CD74 protein levels were analyzed by Western blot and flow cytometry. We identified placental macrophages to express CD74 by immunofluorescence, flow cytometry and RT-PCR. CD74-positive macrophages were significantly reduced in preeclamptic placentas compared to controls. CD74-silenced macrophages showed that the adhesion molecules ALCAM, ICAM4, and Syndecan-2, as well as macrophage adhesion to trophoblasts were diminished. Naive and activated macrophages lacking CD74 showed a shift towards a pro-inflammatory signature with an increased secretion of TNF , CCL5, and MCP-1, when co-cultured with trophoblasts compared to control macrophages. Trophoblasts stimulated by these factors express more CYP2J2, sFlt1, TNF and IL-8. CD74-knockout mice showed disturbed placental morphology, reduced junctional zone, smaller placentas and impaired spiral artery remodeling with fetal growth restriction. Conclusions: CD74 downregulation in placental macrophages is present in preeclampsia. CD74 downregulation leads to altered macrophage activation towards a pro-inflammatory signature and a disturbed crosstalk with trophoblasts.

Macrophage Migration Inhibitory Factor (MIF) Deficiency Exacerbates Aging-Induced Cardiac Remodeling and Dysfunction Despite Improved Inflammation: Role of Autophagy Regulation.

Abstract: Aging leads to unfavorable geometric and functional sequelae in the heart. The proinflammatory cytokine macrophage migration inhibitory factor (MIF) plays a role in the maintenance of cardiac homeostasis under stress conditions although its impact in cardiac aging remains elusive. This study was designed to evaluate the role of MIF in aging-induced cardiac anomalies and the underlying mechanism involved. Cardiac geometry, contractile and intracellular Ca2+ properties were examined in young (3–4 mo) or old (24 mo) wild type and MIF knockout (MIF−/−) mice. Our data revealed that MIF knockout exacerbated aging-induced unfavorable structural and functional changes in the heart. The detrimental effect of MIF knockout was associated with accentuated loss in cardiac autophagy with aging. Aging promoted cardiac inflammation, the effect was attenuated by MIF knockout. Intriguingly, aging-induced unfavorable responses were reversed by treatment with the autophagy inducer rapamycin, with improved myocardial ATP availability in aged WT and MIF−/− mice. Using an in vitro model of senescence, MIF knockdown exacerbated doxorubicin-induced premature senescence in H9C2 myoblasts, the effect was ablated by MIF replenishment. Our data indicated that MIF knockout exacerbates aging-induced cardiac remodeling and functional anomalies despite improved inflammation, probably through attenuating loss of autophagy and ATP availability in the heart.

Macrophage Migration Inhibitory Factor Mediates Proliferative GN via CD74

Abstract: Pathologic proliferation of mesangial and parietal epithelial cells (PECs) is a hallmark of various glomerulonephritides. Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that mediates inflammation by engagement of a receptor complex involving the components CD74, CD44, CXCR2, and CXCR4. The proliferative effects of MIF may involve CD74 together with the coreceptor and PEC activation marker CD44. Herein, we analyzed the effects of local glomerular MIF/CD74/CD44 signaling in proliferative glomerulonephritides. MIF, CD74, and CD44 were upregulated in the glomeruli of patients and mice with proliferative glomerulonephritides. During disease, CD74 and CD44 were expressed de novo in PECs and colocalized in both PECs and mesangial cells. Stress stimuli induced MIF secretion from glomerular cells in vitro and in vivo, in particular from podocytes, and MIF stimulation induced proliferation of PECs and mesangial cells via CD74. In murine crescentic GN, Mif-deficient mice were almost completely protected from glomerular injury, the development of cellular crescents, and the activation and proliferation of PECs and mesangial cells, whereas wild-type mice were not. Bone marrow reconstitution studies showed that deficiency of both nonmyeloid and bone marrow-derived Mif reduced glomerular cell proliferation and injury. In contrast to wild-type mice, Cd74-deficient mice also were protected from glomerular injury and ensuing activation and proliferation of PECs and mesangial cells. Our data suggest a novel molecular mechanism and glomerular cell crosstalk by which local upregulation of MIF and its receptor complex CD74/CD44 mediate glomerular injury and pathologic proliferation in GN.

MIF allele-dependent regulation of the MIF coreceptor CD44 and role in rheumatoid arthritis

Abstract: Fibroblast-like synoviocytes mediate joint destruction in rheumatoid arthritis and exhibit sustained proinflammatory and invasive properties. CD44 is a polymorphic transmembrane protein with defined roles in matrix interaction and tumor invasion that is also a signaling coreceptor for macrophage migration inhibitory factor (MIF), which engages cell surface CD74. High-expression MIF alleles (rs5844572) are associated with rheumatoid joint erosion, but whether MIF signaling through the CD74/CD44 receptor complex promotes upstream autoimmune responses or contributes directly to synovial joint destruction is unknown. We report here the functional regulation of CD44 by an autocrine pathway in synovial fibroblasts that is driven by high-expression MIF alleles to up-regulate an inflammatory and invasive phenotype. MIF increases CD44 expression, promotes its recruitment into a functional signal transduction complex, and stimulates alternative exon splicing, leading to expression of the CD44v3-v6 isoforms associated with oncogenic invasion. CD44 recruitment into the MIF receptor complex, downstream MAPK and RhoA signaling, and invasive phenotype require MIF and CD74 and are reduced by MIF pathway antagonists. These data support a functional role for high-MIF expression alleles and the two-component CD74/CD44 MIF receptor in rheumatoid arthritis and suggest that pharmacologic inhibition of this pathway may offer a specific means to interfere with progressive joint destruction.

Transcription factor ICBP90 regulates the MIF promoter and immune susceptibility locus

Abstract: The immunoregulatory cytokine macrophage migration inhibitory factor (MIF) is encoded in a functionally polymorphic locus that is linked to the susceptibility of autoimmune and infectious diseases. The MIF promoter contains a 4-nucleotide microsatellite polymorphism (-794 CATT) that repeats 5 to 8 times in the locus, with greater numbers of repeats associated with higher mRNA levels. Because there is no information about the transcriptional regulation of these common alleles, we used oligonucleotide affinity chromatography and liquid chromatography-mass spectrometry to identify nuclear proteins that interact with the -794 CATT5-8 site. An analysis of monocyte nuclear lysates revealed that the transcription factor ICBP90 (also known as UHRF1) is the major protein interacting with the MIF microsatellite. We found that ICBP90 is essential for MIF transcription from monocytes/macrophages, B and T lymphocytes, and synovial fibroblasts, and TLR-induced MIF transcription is regulated in an ICBP90- and -794 CATT5-8 length-dependent manner. Whole-genome transcription analysis of ICBP90 shRNA-treated rheumatoid synoviocytes uncovered a subset of proinflammatory and immune response genes that overlapped with those regulated by MIF shRNA. In addition, the expression levels of ICBP90 and MIF were correlated in joint synovia from patients with rheumatoid arthritis. These findings identify ICBP90 as a key regulator of MIF transcription and provide functional insight into the regulation of the polymorphic MIF locus.

Macrophage migration inhibitory factor drives neutrophil accumulation by facilitating IL-1β production in a murine model of acute gout.

Abstract: This study evaluated the role of macrophage migration inhibitory factor in inflammation caused by monosodium urate crystals. The concentration of macrophage migration inhibitory factor was increased in synovial fluid of patients with acute gout, and there was a positive correlation between intra-articular macrophage migration inhibitory factor and IL-1β concentrations. In mice, the injection of monosodium urate crystals into the knee joint increased the levels of macrophage migration inhibitory factor in macrophages and in inflamed tissue. The injection of recombinant macrophage migration inhibitory factor into the joint of mice reproduced the inflammatory response observed in acute gout, including histologic changes, the recruitment of neutrophils, and increased levels of IL-1β and CXCL1. Importantly, the accumulation of neutrophils and the amount IL-1β in the joints were reduced in macrophage migration inhibitory factor-deficient mice when injected with monosodium urate crystals. We observed a similar effect when we blocked macrophage migration inhibitory factor with (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid or anti-macrophage migration inhibitory factor. In addition, the blockade of IL-1R and CXCR2 reduced recombinant macrophage migration inhibitory factor-induced neutrophil recruitment. Mechanistically, recombinant macrophage migration inhibitory factor is important for the synthesis of il1β mRNA in vivo and in isolated macrophages. Altogether, macrophage migration inhibitory factor promotes neutrophil accumulation and is important for IL-1β production, which are 2 crucial events contributing to the pathogenesis of acute gout.

Endogenous macrophage migration inhibitory factor reduces the accumulation and toxicity of misfolded SOD1 in a mouse model of ALS

Abstract: Mutations in superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease characterized by the loss of upper and lower motor neurons in the brain and spinal cord. It has been suggested that the toxicity of mutant SOD1 results from its misfolding and accumulation on the cytoplasmic faces of intracellular organelles, including the mitochondria and endoplasmic reticulum (ER) of ALS-affected tissues. Recently, macrophage migration inhibitory factor (MIF) was shown to directly inhibit the accumulation of misfolded SOD1 and its binding to intracellular membranes, but the role of endogenous MIF in modulating SOD1 misfolding in vivo remains unknown. To elucidate this role, we bred MIF-deficient mice with SOD1G85R mice, which express a dismutase-inactive mutant of SOD1 and are considered a model of familial ALS. We found that the accumulation of misfolded SOD1, its association with mitochondrial and ER membranes, and the levels of sedimentable insoluble SOD1 aggregates were significantly higher in the spinal cords of SOD1G85R-MIF−/− mice than in their SOD1G85R-MIF+/+ littermates. Moreover, increasing MIF expression in neuronal cultures inhibited the accumulation of misfolded SOD1 and rescued from mutant SOD1-induced cell death. In contrast, the complete elimination of endogenous MIF accelerated disease onset and late disease progression and shortened the lifespan of the SOD1G85R mutant mice. These findings indicate that MIF plays a significant role in the folding and misfolding of SOD1 in vivo, and they have implications for the potential therapeutic role of up-regulating MIF within the nervous system to modulate the selective accumulation of misfolded SOD1.

Predicted structure of MIF/CD74 and RTL1000/CD74 complexes

Abstract: Macrophage migration inhibitory factor (MIF) is a key cytokine in autoimmune and inflammatory diseases that attracts and then retains activated immune cells from the periphery to the tissues. MIF exists as a homotrimer and its effects are mediated through its primary receptor, CD74 (the class II invariant chain that exhibits a highly structured trimerization domain), present on class II expressing cells. Although a number of binding residues have been identified between MIF and CD74 trimers, their spatial orientation has not been established. Using a docking program in silico, we have modeled binding interactions between CD74 and MIF as well as CD74 and a competitive MIF inhibitor, RTL1000, a partial MHC class II construct that is currently in clinical trials for multiple sclerosis. These analyses revealed 3 binding sites on the MIF trimer that each were predicted to bind one CD74 trimer through interactions with two distinct 5 amino acid determinants. Surprisingly, predicted binding of one CD74 trimer to a single RTL1000 antagonist utilized the same two 5 residue determinants, providing strong suggestive evidence in support of the MIF binding regions on CD74. Taken together, our structural modeling predicts a new MIF(CD74)3 dodecamer that may provide the basis for increased MIF potency and the requirement for ~3-fold excess RTL1000 to achieve full antagonism.

A Macrophage Migration Inhibitory Factor Polymorphism Is Associated with Autoimmune Hepatitis Severity in US and Japanese Patients

Abstract: The pathogenesis of autoimmune hepatitis (AIH) is incompletely understood. Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine implicated in the pathophysiology of multiple autoimmune diseases. We recently reported that MIF expression was increased in a US AIH cohort. MIF expression in non-Western AIH patients is unknown. A MIF-173 GC single nucleotide polymorphism in the MIF promoter (rs755622) is clinically associated with steroid resistance in several inflammatory disorders but has not been evaluated in AIH. To compare MIF polymorphisms and their relationship to clinical parameters in AIH patients from the USA and Japan. DNA and matched sera from AIH patients and healthy controls from Japan (N = 52) were compared to the US group. Serum concentrations of MIF and its circulating receptor CD74 were measured by ELISA. MIF-173 GC (rs755622) and MIF-794 CATT5–8 (rs5844572) polymorphisms were analyzed by standard methods. MIF genotypes were correlated with serum ALT and steroid requirements. Serum MIF was increased in Japanese AIH patients versus local controls, in agreement with the US AIH patients. Within both AIH groups, ALT was higher in CC/GC versus GG patients. Further, the steroid requirement was higher in AIH patients with GC/CC genotypes from both groups. In the Japanese patient group, the GC/CC genotype also was associated with acute symptomatic presentation. The MIF-173 CC/GC genotypes may be associated with both higher ALT and maintenance steroid requirements in AIH patients from the USA and Japan. This polymorphism could be a marker of disease severity in AIH patients.

MIF-mediated hemodilution promotes pathogenic anemia in experimental African trypanosomosis

Abstract: Animal African trypanosomosis is a major threat to the economic development and human health in sub-Saharan Africa. Trypanosoma congolense infections represent the major constraint in livestock production, with anemia as the major pathogenic lethal feature. The mechanisms underlying anemia development are ill defined, which hampers the development of an effective therapy. Here, the contribution of the erythropoietic and erythrophagocytic potential as well as of hemodilution to the development of T. congolense-induced anemia were addressed in a mouse model of low virulence relevant for bovine trypanosomosis. We show that in infected mice, splenic extramedullary erythropoiesis could compensate for the chronic low-grade type I inflammation-induced phagocytosis of senescent red blood cells (RBCs) in spleen and liver myeloid cells, as well as for the impaired maturation of RBCs occurring in the bone marrow and spleen. Rather, anemia resulted from hemodilution. Our data also suggest that the heme catabolism subsequent to sustained erythrophagocytosis resulted in iron accumulation in tissue and hyperbilirubinemia. Moreover, hypoalbuminemia, potentially resulting from hemodilution and liver injury in infected mice, impaired the elimination of toxic circulating molecules like bilirubin. Hemodilutional thrombocytopenia also coincided with impaired coagulation. Combined, these effects could elicit multiple organ failure and uncontrolled bleeding thus reduce the survival of infected mice. MIF (macrophage migrating inhibitory factor), a potential pathogenic molecule in African trypanosomosis, was found herein to promote erythrophagocytosis, to block extramedullary erythropoiesis and RBC maturation, and to trigger hemodilution. Hence, these data prompt considering MIF as a potential target for treatment of natural bovine trypanosomosis.

Leishmania-encoded orthologs of macrophage migration inhibitory factor regulate host immunity to promote parasite persistence

Abstract: Leishmania major encodes 2 orthologs of the cytokine macrophage migration inhibitory factor (MIF), whose functions in parasite growth or in the host-parasite interaction are unknown. To determine the importance of Leishmania-encoded MIF, both LmMIF genes were removed to produce an mif(-/-) strain of L. major This mutant strain replicated normally in vitro but had a 2-fold increased susceptibility to clearance by macrophages. Mice infected with mif(-/-) L. major, when compared to the wild-type strain, also showed a 3-fold reduction in parasite burden. Microarray and functional analyses revealed a reduced ability of mif(-/-) L. major to activate antigen-presenting cells, resulting in a 2-fold reduction in T-cell priming. In addition, there was a reduction in inflammation and effector CD4 T-cell formation in mif(-/-) L. major-infected mice when compared to mice infected with wild-type L. major Notably, effector CD4 T cells that developed during infection with mif(-/-) L. major demonstrated statistically significant differences in markers of functional exhaustion, including increased expression of IFN-γ and IL-7R, reduced expression of programmed death-1, and decreased apoptosis. These data support a role for LmMIF in promoting parasite persistence by manipulating the host response to increase the exhaustion and depletion of protective CD4 T cells.-Holowka, T., Castilho, T. M., Baeza Garcia, A., Sun, T., McMahon-Pratt, D., Bucala, R. Leishmania-encoded orthologs of macrophage migration inhibitory factor regulate host immunity to promote parasite persistence.

Editorial: The Enduring Value of Reporting Randomized Controlled Clinical Trials in Arthritis & Rheumatology: 2016 and Beyond.

Abstract: One year ago, we discussed the continued importance of reporting randomized controlled clinical trials in Arthritis & Rheumatology (A&R) (1). The journal encouraged submissions through a fast-track option and consultation with a senior clinical trialist (Dr. Michael Weinblatt) to help facilitate submissions and reviews. The process appears to be working. In 2016, A&R published results of 14 randomized clinical trials (RCTs), whereas during 2014–2015 the number was 7. Perhaps more important, of the RCTs published during the past year, 8 were accepted for fast-track review, and the mean turnaround time for fast-track review was 17 days. The current issue of A&R reports 2 important parallel phase IIb RCTs of the same selective JAK-1 inhibitor, ABT-494 (2,3). These 2 trials evaluated this new JAK-1 inhibitor in 2 populations of patients with rheumatoid arthritis (RA). The study by Genovese et al (2) focuses on patients with moderate-to-severe RA and an inadequate response to methotrexate (MTX), and the study by Kremer et al (3) examines a similar population of patients who have had an inadequate response to a tumor necrosis factor antagonist. These are both highly clinically relevant populations to study for this agent. The investigators tested ABT494 using a range of dosages, and after 12 weeks of treatment, both studies demonstrated positive outcomes for both the primary end point, i.e., the proportion of patients who met the American College of Rheumatology 20% improvement criteria (achieved an ACR20 response) (4), and the secondary end points, i.e., the proportions of patients achieving ACR50 and ACR70 responses and the proportion of patients achieving a score of #3.2 or ,2.6 on the 28-joint Disease Activity Score using the C-reactive protein level (5). As phase IIb studies, there are several aspects of both trials that are worth discussing. Phase II trials are intended to test the effectiveness of treatments in patients with the targeted clinical condition, typically after phase I trials have demonstrated an acceptable safety profile. Different dosages of a drug are often tested against placebo, and trials are often brief but allow for planning of more definitive phase III trials. The 2 trials reported in this issue have led to an active phase III trials program that will likely be reported in the ensuing few years. The emphasis on RCTs by the journal speaks to several issues. First, RCTs provide a very high level of evidence for clinical practice. Determining the value of any new treatment in medicine requires adequately powered and well-conducted RCTs. While an intervention’s safety often can be best determined from phase IV postmarketing surveillance, RCTs provide information to determine the most efficacious treatments that clinicians can offer to patients. Second, our focus on RCTs flows from the journal’s interest in serving its readers, many of whom are practicing rheumatologists looking to offer the best therapies to their patients. Increasingly, patients come to the clinic with information from journals and other sources for providers to consider. Publishing high-quality evidence through RCTs ensures that provider–patient discussions are informed and timely. Finally, RCTs play a vital role in establishing standards of care and defining the future therapeutic armamentarium for rheumatology. Advances in immunology Daniel H. Solomon, MD, MPH (Deputy Editor, A&R): Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts; Richard J. Bucala, MD, PhD (Editor in Chief, A&R): Yale University School of Medicine, New Haven, Connecticut. Address correspondence to Daniel H. Solomon, MD, Division of Rheumatology, Immunology, and Allergy, Brigham and Women’s Hospital, 75 Francis Street, PBB-B3, Boston, MA 02120. E-mail: dhsolomon@partners.org. Submitted for publication August 12, 2016; accepted August 16, 2016.