Biology subjects

Bernhagen, J.

Publications and source records attributed to Bernhagen, J..

10 recordsLinked to original sources

bioRxiv2026

Mapping the MIF-2 Chemokine Interactome Reveals MIF-2-CCL20 Complex Formation in Liver Fibrosis

D-dopachrome tautomerase (D-DT/MIF-2) is an inflammatory cytokine, atypical chemokine (ACK) and member of the macrophage migration-inhibitory factor (MIF) family. While interactions among classical chemokines (CKs) are established, ACK-CK interactions remain underexplored. Here, we screened for MIF-2 binding-partners using a protein array encompassing all CKs and selected ACKs, and validated candidate interactors by surface-plasmon resonance. CCL20/MIP-3 was prioritized based on RNA-sequencing suggesting induction during liver fibrosis. MIF-2/CCL20 complex formation was verified by microscale thermophoresis and interaction interfaces mapped using peptide array and in-silico modeling. The deduced binding-site near the MIF-2 tautomerase pocket was consistent with inhibition of its tautomerase activity by CCL20. We found both proteins abundantly expressed in human liver tissue, with a positive correlation. Pull-down confirmed complex formation and proximity ligation assay demonstrated MIF-2/CCL20 complexes in liver in situ, with higher levels in fibrotic tissue. Functionally, MIF-2/CCL20 complexes suppressed MIF-2-driven CD4 T-cell chemotaxis and fibroblast IL-6 secretion, indicating modulation of immune and stromal responses. This study extends the ACK interactome to MIF-2 and suggests ACK/CK complexes modulate chemokine activities in liver fibrosis.

immunology↗

bioRxiv2025

Neural CXCR4 contributes to neuroimmune modulation of atherosclerosis in a cardio-metabolic Ldlr-/- mouse model

BackgroundAtherosclerosis is a chronic inflammatory disease characterized by metabolic and immune dysregulation. Emerging evidence suggests that specific central nervous system (CNS) regions modulate its progression via neuroimmune cardiovascular interfaces (NICIs). While the C-X-C motif chemokine receptor 4 (CXCR4) is known to participate in atherogenesis by regulating immune cell dynamics and vascular wall responses, the role of neural CXCR4 in atherosclerotic plaque formation remains unclear. MethodsWe generated a Nestin-Cre-mediated conditional Cxcr4 knockout mouse model on a low-density lipoprotein receptor-deficient (Ldlr-/-) background and fed these mice a western diet (WD) for up to 12 weeks to induce atherosclerosis. To evaluate the impact of neural CXCR4 function, we quantified atherosclerotic plaque burden, systemic metabolic parameters and circulating immune cell profiles, comparing neural Cxcr4-deficient mice with corresponding genetic controls. Spatial transcriptomics and RNAscope were employed to map Cxcr4 mRNA and its non-canonical ligand macrophage migration inhibitory factor (Mif) mRNA in neuroimmune-regulatory brain regions, and to assess diet-induced expression changes in relation to neuroinflammatory responses. ResultsNeural conditional deletion of Cxcr4 in Ldlr-/- mice significantly reduced atherosclerotic plaque formation in the aortic arch and aorta, without affecting body weight, lipid levels, glucose tolerance, or circulating immune cells. Cxcr4 gene expression was found to be uniformly low across hypothalamic subregions implicated in neuroimmune regulation of systemic inflammation and atherogenesis. Importantly, WD feeding did not modify this consistently low expression in male Ldlr-/- mice. In contrast, Mif mRNA expression was significantly upregulated in the PVN after 5-day WD feeding, but not after 8 weeks. Exploratory spatial transcriptomic analysis of PVN-containing coronal brain sections from male Ldlr-/- mice suggested that 5-day WD exposure is associated with MIF-CXCR4 signaling and downstream neuroinflammatory pathways in the PVN. ConclusionsThis study identifies neural CXCR4 as a component of neuroimmune modulation in atherosclerosis, exerting its effect independently of systemic metabolic or inflammatory changes. Short-term WD exposure activated gene expression of the CXCR4 ligand Mif in the PVN, pointing to a neuroimmune axis that may promote vascular inflammation and atherosclerotic plaque development. These findings establish a link between CNS CXCR4 and vascular disease and suggest that MIF-CXCR4-dependent neuroimmune pathways may play a role in cardiometabolic risk. Trial registrationNot applicable.

immunology↗

bioRxiv2025

MIF-induced CD74+ microglia/macrophages are clinically relevant disease-associated subpopulations in brain metastasis and other CNS disorders

The upregulation of CD74, a chaperone involved in MHC-II antigen processing 1,2, has been broadly reported in virtually all brain disorders analyzed by single-cell RNA sequencing 3-6. However, its expression is usually interpreted as indicative of antigen presentation. In parallel, CD74 expression has also been described in cancer cells across multiple tumor types, but interestingly in glioma its expression has been mainly identified in the microenvironment. However, the functional contribution of CD74 to disease progression in the brain, and specifically in secondary brain tumors, has not been directly addressed. Here we described that, in contrast to what it has been assumed, the presence of CD74+ microglia/macrophages, which is induced by increased levels of interferon gamma in the brain affected by metastases, does not relate to its canonical pathway. Instead, CD74s alternative function as cytokine receptor is pivotal. Rewired by increasing levels of its ligand MIF, produced by proliferating cancer cells, the CD74 receptor, upon binding to this ligand, translocates to the nucleus activating a NF-{kappa}B-dependent program promoting metastasis progression. A brain metastasis-associated CD74 signature involves a more aggressive progression of the local disease in patients, while it has no clinical correlation with the matched primary tumor. Furthermore, we identified the CD74+ myeloid population in additional brain disorders including Alzheimers disease and multiple sclerosis, which shared a pan-disease non-canonical signature with clinical relevance. The brain-penetrant drug ibudilast, which prevents the binding of MIF to CD74, decreases brain metastases in experimental models in vivo and in patient-derived organotypic cultures ex vivo in a primary tumor-agnostic manner. Our findings suggest that MIF/CD74-induced reprogramming of myeloid cells in brain disorders is a novel vulnerability that could be exploited therapeutically against brain metastases, and possibly other brain disorders, guided by a non-invasive molecular strategy.

cancer biology↗

bioRxiv2023

The novel coronary artery disease risk factor ADAMTS-7 modulates atherosclerotic plaque formation by degradation of TIMP-1

BackgroundThe ADAMTS7 locus was genome-wide significantly associated with coronary artery disease (CAD). Lack of the extracellular matrix (ECM) protease ADAMTS-7 was shown to reduce atherosclerotic plaque formation. ObjectiveTo identify molecular mechanisms and downstream targets of ADAMTS-7 mediating risk of atherosclerosis. MethodsTargets of ADAMTS-7 were identified by high-resolution mass spectrometry of atherosclerotic plaques from Apoe-/- and Apoe-/-Adamts7-/- mice. ECM proteins were identified using solubility profiling. Putative targets were validated using immunofluorescence, in vitro degradation assays, co-immunoprecipitation, and Forster resonance energy transfer (FRET)-based protein-protein interaction assays. ADAMTS7 expression was measured in fibrous caps of human carotid artery plaques. ResultsIn humans, ADAMTS7 expression was higher in caps of unstable as compared to stable carotid plaques. Compared to Apoe-/- mice, atherosclerotic aortas of Apoe-/- mice lacking Adamts-7 (Apoe-/-Adamts7-/-) contained higher protein levels of tissue inhibitor of metalloproteases 1 (Timp-1). In co-immunoprecipitation experiments, the catalytic domain of ADAMTS-7 bound to TIMP-1, which was degraded in the presence of ADAMTS-7 in vitro. ADAMTS-7 reduced the inhibitory capacity of TIMP-1 at its canonical target matrix metalloprotease 9 (MMP-9) As a downstream mechanism, we investigated collagen content in plaques of Apoe-/- and Apoe-/-Adamts7-/- mice after Western diet. Picrosirius red staining of the aortic root revealed less collagen as a readout of higher MMP-9 activity in Apoe-/- as compared to Apoe-/- Adamts7-/- mice. In order to facilitate high-throughput screening for ADAMTS-7 inhibitors with the aim to decrease TIMP-1 degradation, we designed a FRET-based assay targeting the ADAMTS-7 catalytic site. ConclusionADAMTS-7, which is induced in unstable atherosclerotic plaques, decreases TIMP-1 stability reducing its inhibitory effect on MMP-9, which is known to promote collagen degradation and is likewise genome-wide significantly associated with CAD. Disrupting the interaction of ADAMTS-7 and TIMP-1 might be a strategy to increase collagen content and plaque stability for reduction of atherosclerosis-related events.

molecular biology↗

bioRxiv2023

Structures of Arabidopsis thaliana MDL Proteins and Synergistic Effects with the Cytokine MIF on Human Receptors

Vertebrates have developed effective immune mechanisms to fight microbial attacks, relying on a sophisticated network of innate and adaptive responses, a circulatory system, and numerous orchestrating soluble mediators such as cytokines. Mammalian macrophage migration inhibitory factor (MIF) and its paralog D-dopachrome tautomerase (D-DT/MIF-2) are multifunctional inflammatory cytokines with chemokine-like properties that modulate immunity. Plants possess orthologous MIF/D-DT-like (MDL) proteins, whose function is largely unexplored. Driven by the previous discovery of cross-kingdom mimicry of plant (Arabidopsis thaliana) MDL proteins and human MIF receptor signaling, we here characterized the structures of the three A. thaliana MDLs by X-ray crystallography and explored the mechanism underlying the interplay between plant MDLs, human MIF, and its receptors. We obtained high-resolution structures at 1.56 [A], 1.40 [A], and 2.00 [A] resolution for MDL1, MDL2, and MDL3, respectively, revealing a typical trimeric assembly and a high three-dimensional similarity to human MIF. Although residues at the catalytic site of the three MDLs show high identity to human MIF, the proteins showed low tautomerase activity for the substrate 4-hydroxyphenylpyruvate (HPP). Structural differences likely explain the enzymatic inactivity of plant MDLs for HPP. Strikingly, employing in vitro, in vivo, and in planta test systems, we found that MIF and MDL proteins interact with each other and have the capacity to form hetero-oligomeric complexes. The functional consequences of this interaction were demonstrated applying a yeast-based reporter system specific for the MIF chemokine receptors CXCR2 and CXCR4. MDLs not only triggered receptor signaling on their own, but exhibited pronounced synergism regarding the activation of the CXCR2- and CXCR4-dependent signaling pathways, when co-applied with MIF. These findings were substantiated by the co-administration of pharmacological inhibitors that either disrupt MIF receptor binding or block the catalytic cavity. Moreover, biochemical and biophysical experiments using an allosteric oligomer-specific MIF inhibitor established hexa-oligomer formation between MIF and MDLs as the putative basis for the synergistic effect. Our results are the starting point for a mechanistic understanding of the immunomodulatory activity of a family of highly conserved plant proteins. One Sentence SummaryA. thaliana MDLs and human macrophage inhibitory factor interact with each other and induce synergistic effects in activating CXCR2 and CXCR4.

immunology↗

bioRxiv2021

MIF-2/D-DT is an atypical atherogenic chemokine that promotes advanced atherosclerosis and hepatic lipogenesis

Atherosclerosis is the underlying cause of cardiovascular diseases (CVDs) such as myocardial infarction and ischemic stroke. It is a lipid-triggered chronic inflammatory condition of the arterial vascular wall that is driven by various inflammatory pathways including atherogenic cytokines and chemokines. D-dopachrome tautomerase (D-DT), also known as macrophage migration inhibitory factor-2 (MIF-2), belongs to the MIF protein family, which is best known for its pathogenic role in a variety of inflammatory and immune conditions including CVDs. While MIF is well known as a promoter of atherogenic processes, MIF-2 has not been studied in atherosclerosis. Here, we investigated atherosclerosis in hyperlipidemic Mif-2-/-Apoe-/- mice and studied the role of MIF-2 in various atherogenic assays in vitro. We found that global Mif-2 deficiency as well as its pharmacological blockade by 4-CPPC protected against atherosclerotic lesion formation and vascular inflammation in models of early and advanced atherogenesis. On cellular level, MIF-2 promoted monocyte migration in 2D and 3D and monocyte arrest on aortic endothelial monolayers, promoted B-cell chemotaxis in vitro and B-cell homing in vivo, and increased macrophage foam cell formation. Dose curves and direct comparison in a 3D migration set-up suggest that MIF-2 may be a more potent chemokine than MIF for monocytes and B cells. We identify CXCR4 as a novel receptor for MIF-2. The evidence relies on a CXCR4 inhibitor, CXCR4 internalization experiments, MIF-2/CXCR4 binding studies by yeast-CXCR4 transformants, and fluorescence spectroscopic titrations with a soluble CXCR4 surrogate. Of note, Mif-2-/-Apoe-/- mice exhibited decreased plasma cholesterol and triglyceride levels, lower body weights, smaller livers, and profoundly reduced hepatic lipid accumulation compared to Apoe-/- mice. Mechanistic experiments in Huh-7 hepatocytes suggest that MIF-2 regulates the expression and activation of sterol-regulatory element binding protein-1 and -2 (SREBP-1, SREBP-2) to induce lipogenic downstream genes such as FASN and LDLR, while it attenuated the activation of the SREBP inhibiting AMPK pathway. Studies using receptor Inhibitors showed that SREBP activation and hepatic lipoprotein uptake by MIF-2 is mediated by both CXCR4 and CD74. Lastly and in line with a combined role of MIF-2 in vascular inflammation and hepatic lipid accumulation, MIF-2 was found to be profoundly upregulated in unstable human carotid plaques, underscoring a critical role for MIF-2 in advanced stages of atherosclerosis. Together, these data identify MIF-2 as a novel atherogenic chemokine and CXCR4 ligand that not only promotes lesion formation and vascular inflammation but also strongly affects hepatic lipogenesis in an SREBP-mediated manner, possibly linking atherosclerosis and hepatic steatosis.

immunology↗

bioRxiv2021

Link between aging and atheroprotection in Mif-deficient atherosclerotic mice

AbstractAtherosclerosis is a lipid-triggered chronic inflammatory condition of our arteries and the main underlying pathology of myocardial infarction and stroke. Pathogenesis is age-dependent, but the mechanistic links between disease progression, age, and atherogenic cytokines and chemokines are incompletely understood. Here, we studied the chemokine-like inflammatory cytokine macrophage migration inhibitory factor (MIF) in atherogenic Apoe-/- mice across different stages of aging and cholesterol-rich high-fat diet (HFD). MIF promotes atherosclerosis by mediating atherogenic monocyte and T-cell recruitment, amplifying lesional inflammation, and suppressing atheroprotective B-cell responses. However, age-related links between atherogenesis and MIF and its role in advanced atherosclerosis in aged mice have not been systematically explored. We compared effects of global Mif-gene deficiency in 30-, 42-, and 48-week-old Apoe-/- mice on HFD for 24, 36, or 42 weeks, respectively, and in 52-week-old mice on a 6-week HFD. While a regio-specific atheroprotective phenotype of Mif-deficiency was observed in the 30/24-week-old group, atheroprotection was not detected in the 48/42- and 52/6-week-old groups, suggesting that atheroprotection afforded by global Mif-gene deletion differs across aging stages and atherogenic diet duration. We identify a combination of mechanisms that could explain this phenotype: i) Mif-deficiency promotes lesional Trem2+ macrophage numbers in younger but not aged mice; ii) Mif-deficiency favors formation of lymphocyte-rich stage-I/II ATLOs in younger mice but ATLO numbers equalize with those in Apoe-/- controls in the older mice; and iii) plasma anti-oxLDL-IgM antibody levels are decreased in aged Mif-deficient mice. Of note, these three markers (Trem2+ macrophages, ATLOs, anti-oxLDL-IgM antibodies) have been previously linked to atheroprotection. Together, our study thus suggests that regio-specific atheroprotection due to global Mif-gene deficiency in atherogenic Apoe-/- mice is lost upon advanced aging and identifies mechanisms that could explain this phenotype shift. These observations may have implications for translational MIF- directed strategies.

immunology↗

bioRxiv2021

Heterocomplexes between the Atypical Chemokine MIF and the CXC-Motif Chemokine CXCL4L1 Regulate Inflammation and Thrombus Formation

To fulfil their orchestrating function in immune cell trafficking in homeostasis and disease, a network of 49 chemokines and 23 receptors capitalizes on features of specificity, redundancy, and functional selectivity such as biased agonism. The discovery of the chemokine interactome, i.e. heteromeric chemokine-chemokine interactions, even across CC- and CXC-class borders, has further expanded the complexity within the network. Moreover, some inflammatory mediators, which are not structurally linked to classical CC-, CXC-, CX3C-, or C-chemokines, can bind to chemokine receptors and behave as atypical chemokines (ACKs). We identified the cytokine macrophage migration inhibitory factor (MIF) as an ACK that binds to the chemokine receptors CXCR2 and CXCR4 to promote atherogenic leukocyte recruitment. Here, we hypothesized that chemokine-chemokine interactions extend to ACKs and that MIF may form heterocomplexes with classical chemokines. We tested this hypothesis, applying an unbiased chemokine protein binding array. The platelet chemokine CXCL4L1, but not its variant CXCL4 or the CXCR2/CXCR4 ligands CXCL8 or CXCL12, was identified as a candidate interactor. MIF/CXCL4L1 complexation was verified by co-immunoprecipitation, surface plasmon-resonance analysis, and microscale thermophoresis, which also established high-affinity binding (KD{asymp}100-150 nM). The binding interface was predicted by peptide array-based mapping and molecular docking. We next determined whether heterocomplex formation modulates inflammatory and atherogenic activities of MIF. MIF-elicited T-cell chemotaxis as assessed in a 3D-matrix-based live cell-imaging set-up was abrogated, when cells were co-incubated with MIF and CXCL4L1. Heterocomplexation also blocked MIF-triggered migration of Egfp+ microglia in cortical cultures in situ. Of note, CXCL4L1 blocked the binding of Alexa-MIF to a soluble ectodomain mimic of CXCR4 and co-incubation with CXCL4L1 attenuated MIF-triggered dynamic mass redistribution in HEK293-CXCR4 transfectants, indicating that complex formation interferes with MIF/CXCR4 pathways. As MIF and CXCL4L1 are abundant platelet products, we finally tested their role in platelet activation. Multi-photon microscopy, FLIM- FRET, and proximity ligation assay visualized heterocomplexes in platelet aggregates and clinical human thrombus sections. Moreover, heterocomplex formation inhibited MIF- stimulated thrombus formation under flow and skewed the morphology of adhering platelets from a large to a small lamellipodia phenotype. Together, our study establishes a novel molecular interaction, adding to the complexity of the chemokine interactome and chemokine/receptor network. MIF/CXCL4L1, or more generally, ACK/CXC-motif chemokine heterocomplexes may be promising target structures to modulate inflammation and thrombosis.

immunology↗

bioRxiv2021

CCL2/CCR2 inhibition in atherosclerosis: a meta-analysis of preclinical studies

RationaleThe CC-chemokine ligand-2 (CCL2)/ CC-chemokine receptor-2 (CCR2) axis governs monocyte recruitment to atherosclerotic lesions. Coherent evidence from experimental studies employing genetic deletion of CCL2 or CCR2 and human epidemiological studies support a causal involvement of the CCL2/CCR2 axis in atherosclerosis. Still, preclinical studies testing pharmacological inhibition of CCL2 or CCR2 in atheroprone mice apply widely different approaches and report inconsistent results, thus halting clinical translation. ObjectiveTo systematically review and meta-analyze preclinical studies pharmacologically targeting the CCL2/CCR2 axis in atherosclerosis in an effort to inform the design of future trials. Methods and ResultsWe identified 14 studies testing CCL2/CCR2 inhibition using 11 different pharmacological agents in mouse models of atherosclerosis. In meta-analyses, blockade of CCL2 or CCR2 attenuated atherosclerotic lesion size in the aortic root or arch (g=-0.75 [-1.17 to -0.32], p=6x10-4; N=171/171 mice in experimental/control group), the carotid (g=-2.39 [-4.23 to -0.55], p=0.01; N=24/25) and the femoral artery (g=-2.38 [-3.50 to -1.26], p=3x10-5; N=10/10). Furthermore, CCL2/CCR2 inhibition reduced intralesional macrophage accumulation and increased smooth muscle cell content and collagen deposition, consistent with a plaque-stabilizing effect. While there was heterogeneity across studies, the effects of CCL2/CCR2 inhibition on lesion size correlated with reductions in plaque macrophage accumulation, in accord with a prominent role of CCL2/CCR2 signaling in monocyte recruitment. Subgroup analyses revealed similar efficacy of both CCL2- and CCR2-inhibiting approaches across different atherosclerosis models in reducing lesion size and intralesional macrophage accumulation, but stronger atheroprotective effects in carotid and femoral arteries, as compared to the aorta. ConclusionsPharmacological targeting of CCL2 or CCR2 lowers atherosclerotic lesion burden and confers plaque stability in mice across different vascular territories, drug candidates, and models of atherosclerosis. Our findings in conjunction with recent human data highlight the translational potential of targeting the CCL2/CCR2 axis in atherosclerosis and can inform future clinical trials. Subject codesatherosclerosis, inflammation, vascular biology, translational studies

immunology↗

bioRxiv2020

Positioning of nucleosomes containing γ-H2AXprecedes active DNA demethylation and transcription initiation

In addition to nucleosomes, chromatin contains non-histone chromatin-associated proteins, of which the high-mobility group (HMG) proteins are the most abundant. Chromatin-mediated regulation of transcription involves DNA methylation and histone modifications. However, the order of events and the precise function of HMG proteins during transcription initiation remain unclear. Here we show that HMG AT-hook 2 protein (HMGA2) induces DNA nicks at the transcription start site, which are required by the histone chaperone FACT (facilitates chromatin transcription) complex to incorporate nucleosomes containing the histone variant H2A.X. Further, phosphorylation of H2A.X at S139 ({gamma}-H2AX) is required for repair-mediated DNA demethylation and transcription activation. The relevance of these findings is demonstrated within the context of TGFB1 signaling and idiopathic pulmonary fibrosis, suggesting therapies against this lethal disease. Our data support that chromatin opening during transcriptional initiation involves intermediates with DNA breaks that subsequently require DNA repair mechanisms to ensure the integrity of the genome.

molecular biology↗