'Nur'turing tumor T cell tolerance and exhaustion: novel function for Nuclear Receptor Nur77 in immunity.

The nuclear receptor Nur77 is expressed in a multitude of tissues, regulating cell differentiation and homeostasis. Dysregulation of Nur77 signaling is associated with cancer, cardiovascular disease, and disorders of the CNS. The role of Nur77 in T cells has been studied for almost 30 years now. There is a clear appreciation that Nur77 is crucial for apoptosis of self-reactive T cells. However, the regulation and function of Nur77 in mature T cells remains largely unclear. In an exciting development, Nur77 has been recently demonstrated to impinge on cancer immunotherapy involving chimeric antigen receptor (CAR) T cells and tumor infiltrating lymphocytes (TILs). These studies indicated that Nur77 deficiency reduced T cell tolerance and exhaustion, thus raising the effectiveness of immune therapy in mice. Based on these novel insights, it may be proposed that regulation of Nur77 activity holds promise for innovative drug development in the field of cellular immunotherapy in cancer. In this review, we therefore summarize the role of Nur77 in T cell selection and maturation; and further develop the idea of targeting its activity in these cells as a potential strategy to augment current cancer immunotherapy treatments.

Exhausted CD8+ T cells exhibit low and strongly inhibited TCR signaling during chronic LCMV infection.

Chronic viral infections are often associated with impaired CD8+ T cell function, referred to as exhaustion. Although the molecular and cellular circuits involved in CD8+ T cell exhaustion are well defined, with sustained presence of antigen being one important parameter, how much T cell receptor (TCR) signaling is actually ongoing in vivo during established chronic infection is unclear. Here, we characterize the in vivo TCR signaling of virus-specific exhausted CD8+ T cells in a mouse model, leveraging TCR signaling reporter mice in combination with transcriptomics. In vivo signaling in exhausted cells is low, in contrast to their in vitro signaling potential, and despite antigen being abundantly present. Both checkpoint blockade and adoptive transfer of naïve target cells increase TCR signaling, demonstrating that engagement of co-inhibitory receptors curtails CD8+ T cell signaling and function in vivo.

Liang-Ge-San, a classic traditional Chinese medicine formula, attenuates acute inflammation in zebrafish and RAW 264.7 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Liang-Ge-San (LGS) is a traditional Chinese medicine formula that commonly used in acute inflammatory diseases. However, the anti-inflammatory effects and the underlying mechanisms of LGS are not fully studied. AIM OF THE STUDY: This study aims to investigate the anti-inflammatory activity and explore the underlying mechanisms of LGS in zebrafish and cell inflammation models. MATERIALS AND METHODS: LPS-induced zebrafish inflammation model was established by LPS-yolk microinjection. The protective effect of LGS on zebrafish injected with LPS was observed using survival analysis. Infiltration of inflammatory cells was determined by H&E staining assay. Expression levels of key inflammatory cytokines TNF-α and IL-6 were measured by q-PCR assay. Recruitment of neutrophils and macrophages were observed by fluorescence microscopy, SB staining and NR staining. In vitro anti-inflammatory effects of LGS were evaluated on LPS-stimulated RAW 264.7 cells. The generation of IL-6 and TNF-α was detected by ELISA. The protein expression levels of JNK, p-JNK (Thr183/Tyr185), Nur77 and p-Nur77 (Ser351) were determined by Western blotting. Finally, two additional inflammatory models in zebrafish, which were induced by CuSO4 or tail fin injury, were also established and the recruitment of neutrophils and macrophages were observed for the determination of the anti-inflammatory activity of LGS. RESULTS: LGS protected zebrafish against LPS-induced death and dose-dependently inhibited LPS-induced acute inflammatory response in zebrafish, as indicated by increased survival rate, reduced infiltration of inflammatory cells, decreased recruitment of macrophages and neutrophils, and downregulated expression levels of TNF-α and IL-6. Additionally, LGS inhibited the secretion of TNF-α and IL-6, increased the expression of Nur77, and reduced the expression of p-Nur77 (Ser351) and p-JNK (Thr183/Tyr185) in LPS-stimulated RAW 264.7 cells. The anti-inflammatory action of LGS was also observed in another two zebrafish inflammation models, which was supported by the inhibition on neutrophils and macrophages recruitment. CONCLUSION: The present study demonstrates that LGS possesses anti-inflammatory activity in zebrafish inflammation models and LPS-stimulated RAW 264.7 cells, which is related to the inhibition on p-JNK and p-Nur77. This finding provides a pharmacological basis for LGS in the control of inflammatory disorder.

Adaptation by naïve CD4+ T cells to self-antigen-dependent TCR signaling induces functional heterogeneity and tolerance.

Naïve CD4+ T cells experience weak T cell receptor (TCR) signals induced by self-peptides presented by MHC II. To investigate how these "basal" TCR signals influence responses to agonist TCR ligand stimulation, we analyzed naïve CD4+ cells expressing varying amounts of CD5, Ly6C, and Nur77-GFP, markers that reflect the strength of basal TCR signaling. Phenotypic analyses indicate that the broadest range of basal TCR signal strength can be visualized by a combination of Nur77-GFP and Ly6C. A range of basal TCR signaling is detectable even in populations that express identical TCRs. Whereas moderate basal TCR signal strength correlates with higher IL-2 secretion at early time points following TCR stimulation, weak basal TCR signaling correlated with higher IL-2 secretion at later time points. We identify a population of Nur77-GFPHI Ly6C- cells that could not be reliably marked by either of CD5, Ly6C, or Nur77-GFP alone. These cells experience the strongest basal TCR signaling, consistently produce less IL-2, and express PD-1 and markers associated with anergy, such as Grail and Cbl-b. We propose that adaptation to the strength of basal TCR signaling drives the phenotypic and functional heterogeneity of naïve CD4+ cells.

Nur77 Links Chronic Antigen Stimulation to B Cell Tolerance by Restricting the Survival of Self-Reactive B Cells in the Periphery.

Nur77 (Nr4a1) belongs to a small family of orphan nuclear receptors that are rapidly induced by BCR stimulation, yet little is known about its function in B cells. We have previously characterized a reporter of Nr4a1 transcription, Nur77-eGFP, in which GFP expression faithfully detects Ag encounter by B cells in vitro and in vivo. In this study, we report that Nur77 expression correlates with the degree of self-reactivity, counterselection, and anergy among individual B cell clones from two distinct BCR transgenic mouse models but is dispensable for all of these tolerance mechanisms. However, we identify a role for Nur77 in restraining survival of self-reactive B cells in the periphery under conditions of competition for a limited supply of the survival factor BAFF. We find that Nur77 deficiency results in the progressive accumulation of self-reactive B cells in the mature repertoire with age and is sufficient to break B cell tolerance in VH3H9 H chain transgenic mice. We thus propose that Nur77 is upregulated in self-reactive B cells in response to chronic Ag stimulation and selectively restricts the survival of these cells, gradually pruning self-reactivity from the mature repertoire to impose a novel layer of peripheral B cell tolerance.

Mesenchymal COX2-PG secretome engages NR4A-WNT signalling axis in haematopoietic progenitors to suppress anti-leukaemia immunity.

The bone marrow (BM) microenvironment (niche) plays important roles in supporting normal/abnormal haematopoiesis. We investigated the interaction between leukaemic mesenchymal niche and haematopoietic stem and progenitor cells (HSPCs) using the model of Fanconi anaemia (FA), a genetic disorder characterized by BM failure and leukaemia. Healthy donor HSPCs co-cultured on mesenchymal stromal cells (MSCs) derived from FA patients with acute myeloid leukaemia (AML) exhibited higher human engraftment and myeloid expansion in Non-obese diabetic severe combined immunodeficiency IL-2γ-/- /SGM3 recipients. Untargeted metabolomics analysis revealed the progressively elevated prostaglandins (PGs) in the MSCs of FA patients with myelodysplastic syndromes (MDS) and AML. Reduced secretion of PGs subsequent to inflammatory cyclooxygenase 2 (COX2) inhibition ameliorated HSPC/myeloid expansion. Transcriptome analysis demonstrated dysregulation of genes involved in the NR4A family of transcription factors (TFs) and WNT/ß-catenin signalling pathway in FA-AML-MSC-co-cultured-CD34+ cells. COX2 inhibition led to significantly decreased NR4A TFs and WNT signalling genes expression. Mechanistically, NR4A1 and NR4A2 synergistically activate the CTNNB1 gene promoter . Knocking down CTNNB1 or NR4A1 in AML-MSC-co-cultured-CD34+ cells increased leukaemia-reactive T-effector cells production and rescued anti-leukaemia immunity. Together, these findings suggest that specific interactions between leukaemic mesenchymal niche and HSPCs orchestrate a novel COX2/PG-NR4A/WNT signalling axis, connecting inflammation, cellular metabolism and cancer immunity.

Nur77 serves as a molecular brake of the metabolic switch during T cell activation to restrict autoimmunity.

T cells critically depend on reprogramming of metabolic signatures to meet the bioenergetic demands during activation and clonal expansion. Here we identify the transcription factor Nur77 as a cell-intrinsic modulator of T cell activation. Nur77-deficient T cells are highly proliferative, and lack of Nur77 is associated with enhanced T cell activation and increased susceptibility for T cell-mediated inflammatory diseases, such as CNS autoimmunity, allergic contact dermatitis and collagen-induced arthritis. Importantly, Nur77 serves as key regulator of energy metabolism in T cells, restricting mitochondrial respiration and glycolysis and controlling switching between different energy pathways. Transcriptional network analysis revealed that Nur77 modulates the expression of metabolic genes, most likely in close interaction with other transcription factors, especially estrogen-related receptor α. In summary, we identify Nur77 as a transcriptional regulator of T cell metabolism, which elevates the threshold for T cell activation and confers protection in different T cell-mediated inflammatory diseases.

The role of monocytosis and neutrophilia in atherosclerosis.

Monocytosis and neutrophilia are frequent events in atherosclerosis. These phenomena arise from the increased proliferation of hematopoietic stem and multipotential progenitor cells (HSPCs) and HSPC mobilization from the bone marrow to other immune organs and circulation. High cholesterol and inflammatory signals promote HSPC proliferation and preferential differentiation to the myeloid precursors (i.e., myelopoiesis) that than give rise to pro-inflammatory immune cells. These cells accumulate in the plaques thereby enhancing vascular inflammation and contributing to further lesion progression. Studies in animal models of atherosclerosis showed that manipulation with HSPC proliferation and differentiation through the activation of LXR-dependent mechanisms and restoration of cholesterol efflux may have a significant therapeutic potential.

NR4A1 and NR4A3 restrict HSC proliferation via reciprocal regulation of C/EBPα and inflammatory signaling.

Members of the NR4A subfamily of nuclear receptors have complex, overlapping roles during hematopoietic cell development and also function as tumor suppressors of hematologic malignancies. We previously identified NR4A1 and NR4A3 (NR4A1/3) as functionally redundant suppressors of acute myeloid leukemia (AML) development. However, their role in hematopoietic stem cell (HSC) homeostasis remains to be disclosed. Using a conditional Nr4a1/Nr4a3 knockout mouse (CDKO), we show that codepletion of NR4A1/3 promotes acute changes in HSC homeostasis including loss of HSC quiescence, accumulation of oxidative stress, and DNA damage while maintaining stem cell regenerative and differentiation capacity. Molecular profiling of CDKO HSCs revealed widespread upregulation of genetic programs governing cell cycle and inflammation and an aberrant activation of the interferon and NF-κB signaling pathways in the absence of stimuli. Mechanistically, we demonstrate that NR4A1/3 restrict HSC proliferation in part through activation of a C/EBPα-driven antiproliferative network by directly binding to a hematopoietic-specific Cebpa enhancer and activating Cebpa transcription. In addition, NR4A1/3 occupy the regulatory regions of NF-κB-regulated inflammatory cytokines, antagonizing the activation of NF-κB signaling. Taken together, our results reveal a novel coordinate control of HSC quiescence by NR4A1/3 through direct activation of C/EBPα and suppression of activation of NF-κB-driven proliferative inflammatory responses.

Myeloid receptor CD36 is required for early phagocytosis of myocardial infarcts and induction of Nr4a1-dependent mechanisms of cardiac repair.

Phagocytosis after myocardial infarction (MI) is a prerequisite to cardiac repair. Recruited monocytes clear necrotic cardiomyocytes and differentiate into cardiac macrophages. Some studies have linked apoptotic cell receptors on cardiac macrophages to tissue repair; however, the contribution of precursor monocyte phagocytic receptors, which are the first to interact with the cardiac parenchyma, is unclear. The scavenger receptor cluster of differentiation (CD)36 protein was detected on cardiac Ly6cHI monocytes, and bone marrow-derived Cd36 was essential for both early phagocytosis of dying cardiomyocytes and for smaller infarct sizes in female and male mice after permanent coronary ligation. Cd36 deficiency led to reduced expression of phagocytosis receptor Mertk and nuclear receptor Nr4a1 in cardiac macrophages, the latter previously shown to be required for phagocyte survival. Nr4a1 was required for phagocytosis-induced Mertk expression, and Nr4a1 protein directly bound to Mertk gene regulatory elements. To test the overall contribution of the Cd36-Mertk axis, MI was induced in Cd36-/- Mertk-/- double-knockout mice and led to increases in myocardial rupture. These data implicate monocyte CD36 in the mitigation of early infarct size and transition to Mertk-dependent macrophage function. Increased myocardial rupture in the absence of both Cd36 and Mertk underscore the physiologic significance of phagocytosis during tissue injury.-Dehn, S., Thorp, E. B. Myeloid receptor CD36 is required for early phagocytosis of myocardial infarcts and induction of Nr4a1-dependent mechanisms of cardiac repair.

Exhaustion-associated regulatory regions in CD8+ tumor-infiltrating T cells.

T-cell exhaustion is a progressive loss of effector function and memory potential due to persistent antigen exposure, which occurs in chronic viral infections and cancer. Here we investigate the relation between gene expression and chromatin accessibility in CD8+ tumor-infiltrating lymphocytes (TILs) that recognize a model tumor antigen and have features of both activation and functional exhaustion. By filtering out accessible regions observed in bystander, nonexhausted TILs and in acutely restimulated CD8+ T cells, we define a pattern of chromatin accessibility specific for T-cell exhaustion, characterized by enrichment for consensus binding motifs for Nr4a and NFAT transcription factors. Anti-PD-L1 treatment of tumor-bearing mice results in cessation of tumor growth and partial rescue of cytokine production by the dysfunctional TILs, with only limited changes in gene expression and chromatin accessibility. Our studies provide a valuable resource for the molecular understanding of T-cell exhaustion in cancer and other inflammatory settings.

Deleting an Nr4a1 Super-Enhancer Subdomain Ablates Ly6Clow Monocytes while Preserving Macrophage Gene Function.

Mononuclear phagocytes are a heterogeneous family that occupy all tissues and assume numerous roles to support tissue function and systemic homeostasis. Our ability to dissect the roles of individual subsets is limited by a lack of technologies that ablate gene function within specific mononuclear phagocyte sub-populations. Using Nr4a1-dependent Ly6Clow monocytes, we present a proof-of-principle approach that addresses these limitations. Combining ChIP-seq and molecular approaches we identified a single, conserved, sub-domain within the Nr4a1 enhancer that was essential for Ly6Clow monocyte development. Mice lacking this enhancer lacked Ly6Clow monocytes but retained Nr4a1 gene expression in macrophages during steady state and in response to LPS. Because Nr4a1 regulates inflammatory gene expression and differentiation of Ly6Clow monocytes, decoupling these processes allows Ly6Clow monocytes to be studied independently.

6-Mercaptopurine attenuates tumor necrosis factor-α production in microglia through Nur77-mediated transrepression and PI3K/Akt/mTOR signaling-mediated translational regulation.

BACKGROUND: The pathogenesis of several neurodegenerative diseases often involves the microglial activation and associated inflammatory processes. Activated microglia release pro-inflammatory factors that may be neurotoxic. 6-Mercaptopurine (6-MP) is a well-established immunosuppressive drug. Common understanding of their immunosuppressive properties is largely limited to peripheral immune cells. However, the effect of 6-MP in the central nervous system, especially in microglia in the context of neuroinflammation is, as yet, unclear. Tumor necrosis factor-α (TNF-α) is a key cytokine of the immune system that initiates and promotes neuroinflammation. The present study aimed to investigate the effect of 6-MP on TNF-α production by microglia to discern the molecular mechanisms of this modulation. METHODS: Lipopolysaccharide (LPS) was used to induce an inflammatory response in cultured primary microglia or murine BV-2 microglial cells. Released TNF-α was measured by enzyme-linked immunosorbent assay (ELISA). Gene expression was determined by real-time reverse transcription polymerase chain reaction (RT-PCR). Signaling molecules were analyzed by western blotting, and activation of NF-κB was measured by ELISA-based DNA binding analysis and luciferase reporter assay. Chromatin immunoprecipitation (ChIP) analysis was performed to examine NF-κB p65 and coactivator p300 enrichments and histone modifications at the endogenous TNF-α promoter. RESULTS: Treatment of LPS-activated microglia with 6-MP significantly attenuated TNF-α production. In 6-MP pretreated microglia, LPS-induced MAPK signaling, IκB-α degradation, NF-κB p65 nuclear translocation, and in vitro p65 DNA binding activity were not impaired. However, 6-MP suppressed transactivation activity of NF-κB and TNF-α promoter by inhibiting phosphorylation and acetylation of p65 on Ser276 and Lys310, respectively. ChIP analyses revealed that 6-MP dampened LPS-induced histone H3 acetylation of chromatin surrounding the TNF-α promoter, ultimately leading to a decrease in p65/coactivator-mediated transcription of TNF-α gene. Furthermore, 6-MP enhanced orphan nuclear receptor Nur77 expression. Using RNA interference approach, we further demonstrated that Nur77 upregulation contribute to 6-MP-mediated inhibitory effect on TNF-α production. Additionally, 6-MP also impeded TNF-α mRNA translation through prevention of LPS-activated PI3K/Akt/mTOR signaling cascades. CONCLUSIONS: These results suggest that 6-MP might have a therapeutic potential in neuroinflammation-related neurodegenerative disorders through downregulation of microglia-mediated inflammatory processes.

Transcription factor Nr4a1 couples sympathetic and inflammatory cues in CNS-recruited macrophages to limit neuroinflammation.

The molecular mechanisms that link the sympathetic stress response and inflammation remain obscure. Here we found that the transcription factor Nr4a1 regulated the production of norepinephrine (NE) in macrophages and thereby limited experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. Lack of Nr4a1 in myeloid cells led to enhanced NE production, accelerated infiltration of leukocytes into the central nervous system (CNS) and disease exacerbation in vivo. In contrast, myeloid-specific deletion of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis, protected mice against EAE. Furthermore, we found that Nr4a1 repressed autocrine NE production in macrophages by recruiting the corepressor CoREST to the Th promoter. Our data reveal a new role for macrophages in neuroinflammation and identify Nr4a1 as a key regulator of catecholamine production by macrophages.

Deficiency of Nuclear Receptor Nur77 Aggravates Mouse Experimental Colitis by Increased NFκB Activity in Macrophages.

Nuclear receptor Nur77, also referred to as NR4A1 or TR3, plays an important role in innate and adaptive immunity. Nur77 is crucial in regulating the T helper 1/regulatory T-cell balance, is expressed in macrophages and drives M2 macrophage polarization. In this study we aimed to define the function of Nur77 in inflammatory bowel disease. In wild-type and Nur77-/- mice, colitis development was studied in dextran sodium sulphate (DSS)- and 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced models. To understand the underlying mechanism, Nur77 was overexpressed in macrophages and gut epithelial cells. Nur77 protein is expressed in colon tissues from Crohn's disease and Ulcerative colitis patients and colons from colitic mice in inflammatory cells and epithelium. In both mouse colitis models inflammation was increased in Nur77-/- mice. A higher neutrophil influx and enhanced IL-6, MCP-1 and KC production was observed in Nur77-deficient colons after DSS-treatment. TNBS-induced influx of T-cells and inflammatory monocytes into the colon was higher in Nur77-/- mice, along with increased expression of MCP-1, TNFα and IL-6, and decreased Foxp3 RNA expression, compared to wild-type mice. Overexpression of Nur77 in lipopolysaccharide activated RAW macrophages resulted in up-regulated IL-10 and downregulated TNFα, MIF-1 and MCP-1 mRNA expression through NFκB repression. Nur77 also strongly decreased expression of MCP-1, CXCL1, IL-8, MIP-1α and TNFα in gut epithelial Caco-2 cells. Nur77 overexpression suppresses the inflammatory status of both macrophages and gut epithelial cells and together with the in vivo mouse data this supports that Nur77 has a protective function in experimental colitis. These findings may have implications for development of novel targeted treatment strategies regarding inflammatory bowel disease and other inflammatory diseases.

The transcription factor NR4A1 is essential for the development of a novel macrophage subset in the thymus.

Tissue macrophages function to maintain homeostasis and regulate immune responses. While tissue macrophages derive from one of a small number of progenitor programs, the transcriptional requirements for site-specific macrophage subset development are more complex. We have identified a new tissue macrophage subset in the thymus and have discovered that its development is dependent on transcription factor NR4A1. Functionally, we find that NR4A1-dependent macrophages are critically important for clearance of apoptotic thymocytes. These macrophages are largely reduced or absent in mice lacking NR4A1, and Nr4a1-deficient mice have impaired thymocyte engulfment and clearance. Thus, NR4A1 functions as a master transcription factor for the development of this novel thymus-specific macrophage subset.

Differential roles for Bim and Nur77 in thymocyte clonal deletion induced by ubiquitous self-antigen.

Negative selection, primarily mediated through clonal deletion of self-reactive thymocytes, is critical for establishing self-tolerance and preventing autoimmunity. Recent studies suggest that the molecular mechanisms of negative selection differ depending on the thymic compartment and developmental stage at which thymocytes are deleted. Using the physiological HY(cd4) TCR transgenic model of negative selection against ubiquitous self-antigen, we previously found that one of the principal mediators implicated in clonal deletion, Bim, is required for caspase-3 activation but is ultimately dispensable for negative selection. On the basis of these data, we hypothesized that Nur77, another molecule thought to be a key mediator of clonal deletion, could be responsible for Bim-independent deletion. Despite comparable Nur77 induction in thymocytes during negative selection, Bim deficiency resulted in an accumulation of high-affinity-signaled thymocytes as well as impairment in caspase-mediated and caspase-independent cell death. Although these data suggested that Bim may be required for Nur77-mediated cell death, we found that transgenic Nur77 expression was sufficient to induce apoptosis independently of Bim. However, transgenic Nur77-induced apoptosis was significantly inhibited in the context of TCR signaling, suggesting that endogenous Nur77 could be similarly regulated during negative selection. Although Nur77 deficiency alone did not alter positive or negative selection, combined deficiency in Bim and Nur77 impaired clonal deletion efficiency and significantly increased positive selection efficiency. Collectively, these data shed light on the different roles for Bim and Nur77 during ubiquitous Ag-mediated clonal deletion and highlight potential differences from their reported roles in tissue-restricted Ag-mediated clonal deletion.

Orphan nuclear receptor Nur77 Inhibits Oxidized LDL-induced differentiation of RAW264.7 murine macrophage cell line into dendritic like cells.

BACKGROUND: Nur77 is an orphan nuclear receptor expressed in human atheroma. In vascular cells in vitro, Nur77 expression is induced by pro-inflammatory factors, such as oxidized LDL (oxLDL). METHODS: We analyze the role of Nur77 in the oxLDL-induced differentiation of macrophages into dendritic cells (DC). The murine RAW264.7 macrophage cell line was stably transfected with expression plasmids encoding either GFP or GFP fusions with either full-length Nur77 (GFP-Nur77), Nur77 lacking the DNA binding domain (GFP-Nur77-ΔDBD) or Nur77 lacking the transactivation domain (GFP-Nur77-ΔTAD). RESULTS: GFP-Nur77 overexpression significantly suppressed the effect of oxLDL treatment on DC morphologic changes, expression of DC maturation markers, endocytic activity, allogeneic activation of T cell proliferation, and the activity and secretion of pro-inflammatory cytokines. Analysis of GFP-Nur77-ΔTAD and GFP-Nur77-ΔDBD indicated that the Nur77 DNA binding and transactivation domains were both required for this effect. GFP-Nur77-ΔDBD consistently had the opposite effect to GFP-Nur77, increasing DC-type differentiation in all assays. Interestingly, GFP-Nur77-ΔDBD protein was cytosolic, whereas GFP-Nur77 and GFP-Nur77-ΔTAD were both nuclear. CONCLUSIONS: These data show that GFP-Nur77 inhibited differentiation of oxLDL-treated macrophages into DC. The effects of Nur77 on the macrophage phenotype may involve changes in its subcellular distribution.

Genetic susceptibility and loss of Nr4a1 enhances macrophage-mediated renal injury in CKD.

Nuclear hormone receptors of the NR4A subgroup have been implicated in cancer, atherosclerosis, and metabolic disease. However, little is known about the role of these receptors in kidney health or disease. Nr4a1-deficient rats (Nr4a1(-/-)) developed on a genetic background susceptible to kidney injury (fawn-hooded hypertensive rat [FHH]) were evaluated for BP, proteinuria, renal function, and metabolic parameters from 4 to 24 weeks-of-age. By week 24, Nr4a1(-/-) rats exhibited significantly higher proteinuria (approximately 4-fold) and decreased GFR compared with FHH controls. The severity of tubular atrophy, tubular casts, and interstitial fibrosis increased significantly in Nr4a1(-/-) rats and was accompanied by a large increase in immune cell infiltration, predominantly macrophages and to a lesser extent T cells and B cells. Global transcriptome and network analyses at weeks 8, 16, and 24 identified several proinflammatory genes and pathways differentially regulated between strains. Bone marrow crosstransplantation studies demonstrated that kidney injury in Nr4a1(-/-) rats was almost completely rescued by bone marrow transplanted from FHH controls. In vitro, macrophages isolated from Nr4a1(-/-) rats demonstrated increased immune activation compared with FHH-derived macrophages. In summary, the loss of Nr4a1 in immune cells appears to cause the increased kidney injury and reduced renal function observed in the Nr4a1(-/-) model.