Publications by authors named "Aaron denDekker"

19 Publications

  • Page 1 of 1

Inhibition of macrophage histone demethylase JMJD3 protects against abdominal aortic aneurysms.

J Exp Med 2021 Jun;218(6)

Section of Vascular Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI.

Abdominal aortic aneurysms (AAAs) are a life-threatening disease for which there is a lack of effective therapy preventing aortic rupture. During AAA formation, pathological vascular remodeling is driven by macrophage infiltration, and the mechanisms regulating macrophage-mediated inflammation remain undefined. Recent evidence suggests that an epigenetic enzyme, JMJD3, plays a critical role in establishing macrophage phenotype. Using single-cell RNA sequencing of human AAA tissues, we identified increased JMJD3 in aortic monocyte/macrophages resulting in up-regulation of an inflammatory immune response. Mechanistically, we report that interferon-β regulates Jmjd3 expression via JAK/STAT and that JMJD3 induces NF-κB-mediated inflammatory gene transcription in infiltrating aortic macrophages. In vivo targeted inhibition of JMJD3 with myeloid-specific genetic depletion (JMJD3f/fLyz2Cre+) or pharmacological inhibition in the elastase or angiotensin II-induced AAA model preserved the repressive H3K27me3 on inflammatory gene promoters and markedly reduced AAA expansion and attenuated macrophage-mediated inflammation. Together, our findings suggest that cell-specific pharmacologic therapy targeting JMJD3 may be an effective intervention for AAA expansion.
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http://dx.doi.org/10.1084/jem.20201839DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8008365PMC
June 2021

Dysregulation of intercellular signaling by MOF deletion leads to liver injury.

J Biol Chem 2020 Dec 29. Epub 2020 Dec 29.

Medicine; Biochemistry and Molecular Medicine, University of Southern California, United States.

Epigenetic mechanisms that alter heritable gene expression and chromatin structure play an essential role in many biological processes, including liver function. Human MOF (males absent on the first) is a histone acetyltransferase that is globally downregulated in human steatohepatitis. However, the function of MOF in the liver remains unclear. Here, we report that MOF plays an essential role in adult liver. Genetic deletion of Mof by Mx1-Cre in liver leads to acute liver injury, with increase of lipid deposition and fibrosis akin to human steatohepatitis. Surprisingly, hepatocyte specific Mof deletion had no overt liver abnormality. Using the in vitro co-culturing experiment, we show that Mof deletion-induced liver injury requires coordinated changes and reciprocal signaling between hepatocytes and Kupffer cells, which enables feedforward regulation to augment inflammation and apoptotic responses. At the molecular level, Mof deletion induced characteristic changes in metabolic gene programs, which bore noticeable similarity to the molecular signature of human steatohepatitis. Simultaneous deletion of Mof in both hepatocytes and macrophages results in enhanced expression of inflammatory genes and NO signaling in vitro. These changes, in turn, lead to apoptosis of hepatocytes and lipotoxicity. Our work highlights the importance of histone acetyltransferase MOF in maintaining metabolic liver homeostasis and sheds light on the epigenetic dysregulation in liver pathogenesis.
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http://dx.doi.org/10.1074/jbc.RA120.016079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7948572PMC
December 2020

Epigenetic regulation of the PGE2 pathway modulates macrophage phenotype in normal and pathologic wound repair.

JCI Insight 2020 09 3;5(17). Epub 2020 Sep 3.

Section of Vascular Surgery, Department of Surgery.

Macrophages are a primary immune cell involved in inflammation, and their cell plasticity allows for transition from an inflammatory to a reparative phenotype and is critical for normal tissue repair following injury. Evidence suggests that epigenetic alterations play a critical role in establishing macrophage phenotype and function during normal and pathologic wound repair. Here, we find in human and murine wound macrophages that cyclooxygenase 2/prostaglandin E2 (COX-2/PGE2) is elevated in diabetes and regulates downstream macrophage-mediated inflammation and host defense. Using single-cell RNA sequencing of human wound tissue, we identify increased NF-κB-mediated inflammation in diabetic wounds and show increased COX-2/PGE2 in diabetic macrophages. Further, we identify that COX-2/PGE2 production in wound macrophages requires epigenetic regulation of 2 key enzymes in the cytosolic phospholipase A2/COX-2/PGE2 (cPLA2/COX-2/PGE2) pathway. We demonstrate that TGF-β-induced miRNA29b increases COX-2/PGE2 production via inhibition of DNA methyltransferase 3b-mediated hypermethylation of the Cox-2 promoter. Further, we find mixed-lineage leukemia 1 (MLL1) upregulates cPLA2 expression and drives COX-2/PGE2. Inhibition of the COX-2/PGE2 pathway genetically (Cox2fl/fl Lyz2Cre+) or with a macrophage-specific nanotherapy targeting COX-2 in tissue macrophages reverses the inflammatory macrophage phenotype and improves diabetic tissue repair. Our results indicate the epigenetically regulated PGE2 pathway controls wound macrophage function, and cell-targeted manipulation of this pathway is feasible to improve diabetic wound repair.
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http://dx.doi.org/10.1172/jci.insight.138443DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7526451PMC
September 2020

Palmitate-TLR4 signaling regulates the histone demethylase, JMJD3, in macrophages and impairs diabetic wound healing.

Eur J Immunol 2020 12 20;50(12):1929-1940. Epub 2020 Jul 20.

Section of Vascular Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI, USA.

Chronic macrophage inflammation is a hallmark of type 2 diabetes (T2D) and linked to the development of secondary diabetic complications. T2D is characterized by excess concentrations of saturated fatty acids (SFA) that activate innate immune inflammatory responses, however, mechanism(s) by which SFAs control inflammation is unknown. Using monocyte-macrophages isolated from human blood and murine models, we demonstrate that palmitate (C16:0), the most abundant circulating SFA in T2D, increases expression of the histone demethylase, Jmjd3. Upregulation of Jmjd3 results in removal of the repressive histone methylation (H3K27me3) mark on NFκB-mediated inflammatory gene promoters driving macrophage-mediated inflammation. We identify that the effects of palmitate are fatty acid specific, as laurate (C12:0) does not regulate Jmjd3 and the associated inflammatory profile. Further, palmitate-induced Jmjd3 expression is controlled via TLR4/MyD88-dependent signaling mechanism, where genetic depletion of TLR4 (Tlr4 ) or MyD88 (MyD88 ) negated the palmitate-induced changes in Jmjd3 and downstream NFκB-induced inflammation. Pharmacological inhibition of Jmjd3 using a small molecule inhibitor (GSK-J4) reduced macrophage inflammation and improved diabetic wound healing. Together, we conclude that palmitate contributes to the chronic Jmjd3-mediated activation of macrophages in diabetic peripheral tissue and a histone demethylase inhibitor-based therapy may represent a novel treatment for nonhealing diabetic wounds.
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http://dx.doi.org/10.1002/eji.202048651DOI Listing
December 2020

Epigenetic Regulation of TLR4 in Diabetic Macrophages Modulates Immunometabolism and Wound Repair.

J Immunol 2020 05 23;204(9):2503-2513. Epub 2020 Mar 23.

Section of Vascular Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI 48109;

Macrophages are critical for the initiation and resolution of the inflammatory phase of wound healing. In diabetes, macrophages display a prolonged inflammatory phenotype preventing tissue repair. TLRs, particularly TLR4, have been shown to regulate myeloid-mediated inflammation in wounds. We examined macrophages isolated from wounds of patients afflicted with diabetes and healthy controls as well as a murine diabetic model demonstrating dynamic expression of TLR4 results in altered metabolic pathways in diabetic macrophages. Further, using a myeloid-specific mixed-lineage leukemia 1 (MLL1) knockout ( ), we determined that MLL1 drives expression in diabetic macrophages by regulating levels of histone H3 lysine 4 trimethylation on the promoter. Mechanistically, MLL1-mediated epigenetic alterations influence diabetic macrophage responsiveness to TLR4 stimulation and inhibit tissue repair. Pharmacological inhibition of the TLR4 pathway using a small molecule inhibitor (TAK-242) as well as genetic depletion of either ( ) or myeloid-specific resulted in improved diabetic wound healing. These results define an important role for MLL1-mediated epigenetic regulation of TLR4 in pathologic diabetic wound repair and suggest a target for therapeutic manipulation.
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http://dx.doi.org/10.4049/jimmunol.1901263DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7443363PMC
May 2020

TNF-α regulates diabetic macrophage function through the histone acetyltransferase MOF.

JCI Insight 2020 03 12;5(5). Epub 2020 Mar 12.

Department of Surgery.

A critical component of wound healing is the transition from the inflammatory phase to the proliferation phase to initiate healing and remodeling of the wound. Macrophages are critical for the initiation and resolution of the inflammatory phase during wound repair. In diabetes, macrophages display a sustained inflammatory phenotype in late wound healing characterized by elevated production of inflammatory cytokines, such as TNF-α. Previous studies have shown that an altered epigenetic program directs diabetic macrophages toward a proinflammatory phenotype, contributing to a sustained inflammatory phase. Males absent on the first (MOF) is a histone acetyltransferase (HAT) that has been shown be a coactivator of TNF-α signaling and promote NF-κB-mediated gene transcription in prostate cancer cell lines. Based on MOF's role in TNF-α/NF-κB-mediated gene expression, we hypothesized that MOF influences macrophage-mediated inflammation during wound repair. We used myeloid-specific Mof-knockout (Lyz2Cre Moffl/fl) and diet-induced obese (DIO) mice to determine the function of MOF in diabetic wound healing. MOF-deficient mice exhibited reduced inflammatory cytokine gene expression. Furthermore, we found that wound macrophages from DIO mice had elevated MOF levels and higher levels of acetylated histone H4K16, MOF's primary substrate of HAT activity, on the promoters of inflammatory genes. We further identified that MOF expression could be stimulated by TNF-α and that treatment with etanercept, an FDA-approved TNF-α inhibitor, reduced MOF levels and improved wound healing in DIO mice. This report is the first to our knowledge to define an important role for MOF in regulating macrophage-mediated inflammation in wound repair and identifies TNF-α inhibition as a potential therapy for the treatment of chronic inflammation in diabetic wounds.
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http://dx.doi.org/10.1172/jci.insight.132306DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7141388PMC
March 2020

p53 Integrates Temporal WDR5 Inputs during Neuroectoderm and Mesoderm Differentiation of Mouse Embryonic Stem Cells.

Cell Rep 2020 01;30(2):465-480.e6

Department of Ophthalmology & Visual Sciences, University of Michigan, Ann Arbor, MI, USA; Department of Pathology, University of Michigan, Ann Arbor, MI, USA; Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI, USA; Taubman Institute, University of Michigan, Ann Arbor, MI, USA; Section of Ophthalmology, Surgical Service, Veterans Administration Ann Arbor Healthcare System, Ann Arbor, MI, USA. Electronic address:

How ubiquitous transcription factors (TFs) coordinate temporal inputs from broadly expressed epigenetic factors to control cell fate remains poorly understood. Here, we uncover a molecular relationship between p53, an abundant embryonic TF, and WDR5, an essential member of the MLL chromatin modifying complex, that regulates mouse embryonic stem cell fate. Wild-type Wdr5 or transient Wdr5 knockout promotes a distinct pattern of global chromatin accessibility and spurs neuroectodermal differentiation through an RbBP5-dependent process in which WDR5 binds to, and activates transcription of, neural genes. Wdr5 rescue after its prolonged inhibition targets WDR5 to mesoderm lineage-specifying genes, stimulating differentiation toward mesoderm fates in a p53-dependent fashion. Finally, we identify a direct interaction between WDR5 and p53 that enables their co-recruitment to, and regulation of, genes known to control cell proliferation and fate. Our results unmask p53-dependent mechanisms that temporally integrate epigenetic WDR5 inputs to drive neuroectoderm and mesoderm differentiation from pluripotent cells.
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http://dx.doi.org/10.1016/j.celrep.2019.12.039DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7024586PMC
January 2020

Sepsis Induces Prolonged Epigenetic Modifications in Bone Marrow and Peripheral Macrophages Impairing Inflammation and Wound Healing.

Arterioscler Thromb Vasc Biol 2019 11 5;39(11):2353-2366. Epub 2019 Sep 5.

From the Section of Vascular Surgery, Department of Surgery (F.M.D., A.D., A.D.J., A.S.K., A.T.O., W.J.M., K.A.G.), University of Michigan, Ann Arbor.

Objective: Sepsis represents an acute life-threatening disorder resulting from a dysregulated host response. For patients who survive sepsis, there remains long-term consequences, including impaired inflammation, as a result of profound immunosuppression. The mechanisms involved in this long-lasting deficient immune response are poorly defined. Approach and Results: Sepsis was induced using the murine model of cecal ligation and puncture. Following a full recovery period from sepsis physiology, mice were subjected to our wound healing model and wound macrophages (CD11b+, CD3-, CD19-, Ly6G-) were sorted. Post-sepsis mice demonstrated impaired wound healing and decreased reepithelization in comparison to controls. Further, post-sepsis bone marrow-derived macrophages and wound macrophages exhibited decreased expression of inflammatory cytokines vital for wound repair (IL [interleukin]-1β, IL-12, and IL-23). To evaluate if decreased inflammatory gene expression was secondary to epigenetic modification, we conducted chromatin immunoprecipitation on post-sepsis bone marrow-derived macrophages and wound macrophages. This demonstrated decreased expression of , an epigenetic enzyme, and impaired histone 3 lysine 4 trimethylation (activation mark) at NFκB (nuclear factor kappa-light-chain-enhancer of activated B cells)-binding sites on inflammatory gene promoters in bone marrow-derived macrophages and wound macrophages from postcecal ligation and puncture mice. Bone marrow transplantation studies demonstrated epigenetic modifications initiate in bone marrow progenitor/stem cells following sepsis resulting in lasting impairment in peripheral macrophage function. Importantly, human peripheral blood leukocytes from post-septic patients demonstrate a significant reduction in compared with nonseptic controls.

Conclusions: These data demonstrate that severe sepsis induces stable mixed-lineage leukemia 1-mediated epigenetic modifications in the bone marrow, which are passed to peripheral macrophages resulting in impaired macrophage function and deficient wound healing persisting long after sepsis recovery.
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http://dx.doi.org/10.1161/ATVBAHA.119.312754DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6818743PMC
November 2019

The Histone Methyltransferase Setdb2 Modulates Macrophage Phenotype and Uric Acid Production in Diabetic Wound Repair.

Immunity 2019 08 23;51(2):258-271.e5. Epub 2019 Jul 23.

Department of Surgery, University of Michigan, Ann Arbor, MI, USA; Department of Microbiology and Immunology, University of Michigan, Ann Arbor, MI, USA. Electronic address:

Macrophage plasticity is critical for normal tissue repair to ensure transition from the inflammatory to the proliferative phase of healing. We examined macrophages isolated from wounds of patients afflicted with diabetes and of healthy controls and found differential expression of the methyltransferase Setdb2. Myeloid-specific deletion of Setdb2 impaired the transition of macrophages from an inflammatory phenotype to a reparative one in normal wound healing. Mechanistically, Setdb2 trimethylated histone 3 at NF-κB binding sites on inflammatory cytokine gene promoters to suppress transcription. Setdb2 expression in wound macrophages was regulated by interferon (IFN) β, and under diabetic conditions, this IFNβ-Setdb2 axis was impaired, leading to a persistent inflammatory macrophage phenotype in diabetic wounds. Setdb2 regulated the expression of xanthine oxidase and thereby the uric acid (UA) pathway of purine catabolism in macrophages, and pharmacologic targeting of Setdb2 or the UA pathway improved healing. Thus, Setdb2 regulates macrophage plasticity during normal and pathologic wound repair and is a target for therapeutic manipulation.
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http://dx.doi.org/10.1016/j.immuni.2019.06.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6703945PMC
August 2019

SIRT3 Regulates Macrophage-Mediated Inflammation in Diabetic Wound Repair.

J Invest Dermatol 2019 12 15;139(12):2528-2537.e2. Epub 2019 Jun 15.

Department of Surgery, University of Michigan, Ann Arbor, Michigan, USA; Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA. Electronic address:

Control of inflammation is critical for the treatment of nonhealing wounds, but a delicate balance exists between early inflammation that is essential for normal tissue repair and the pathologic inflammation that can occur later in the repair process. This necessitates the development of novel therapies that can target inflammation at the appropriate time during repair. Here, we found that SIRT3 is essential for normal healing and regulates inflammation in wound macrophages after injury. Under prediabetic conditions, SIRT3 was decreased in wound macrophages and resulted in dysregulated inflammation. In addition, we found that FABP4 regulates SIRT3 in human blood monocytes, and inhibition of FABP4 in wound macrophages decreases inflammatory cytokine expression, making FABP4 a viable target for the regulation of excess inflammation and wound repair in diabetes. Using a series of ex vivo and in vivo studies with genetically engineered mouse models and diabetic human monocytes, we showed that FABP4 expression is epigenetically upregulated in diabetic wound macrophages and, in turn, diminishes SIRT3 expression, thereby promoting inflammation. These findings have significant implications for controlling inflammation and promoting tissue repair in diabetic wounds.
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http://dx.doi.org/10.1016/j.jid.2019.05.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7185380PMC
December 2019

Histone Methylation Directs Myeloid TLR4 Expression and Regulates Wound Healing following Cutaneous Tissue Injury.

J Immunol 2019 03 1;202(6):1777-1785. Epub 2019 Feb 1.

Section of Vascular Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI 48109;

Myeloid cells are critical for orchestrating regulated inflammation during wound healing. TLRs, particularly TLR4, and its downstream-signaling MyD88 pathway play an important role in regulating myeloid-mediated inflammation. Because an initial inflammatory phase is vital for tissue repair, we investigated the role of TLR4-regulated, myeloid-mediated inflammation in wound healing. In a cutaneous tissue injury murine model, we found that TLR4 expression is dynamic in wound myeloid cells during the course of normal wound healing. We identified that changes in myeloid TLR4 during tissue repair correlated with increased expression of the histone methyltransferase, mixed-lineage leukemia 1 (MLL1), which specifically trimethylates the histone 3 lysine 4 (H3K4me3) position of the TLR4 promoter. Furthermore, we used a myeloid-specific Mll1 knockout ( ) to determine MLL1 drives expression during wound healing. To understand the critical role of myeloid-specific TLR4 signaling, we used mice deficient in ( ), (), and myeloid-specific to demonstrate delayed wound healing at early time points postinjury. Furthermore, in vivo wound myeloid cells isolated from and wounds demonstrated decreased inflammatory cytokine production. Importantly, adoptive transfer of monocyte/macrophages from wild-type mice trafficked to wounds with restoration of normal healing and myeloid cell function in -deficient mice. These results define a role for myeloid-specific, MyD88-dependent TLR4 signaling in the inflammatory response following cutaneous tissue injury and suggest that MLL1 regulates TLR4 expression in wound myeloid cells.
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http://dx.doi.org/10.4049/jimmunol.1801258DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6401313PMC
March 2019

Chorioamnionitis exposure remodels the unique histone modification landscape of neonatal monocytes and alters the expression of immune pathway genes.

FEBS J 2019 01 22;286(1):82-109. Epub 2018 Dec 22.

Department of Pathology, Michigan Medicine, Ann Arbor, MI, USA.

Chorioamnionitis is an intrauterine infection involving inflammation of the chorion, amnion, and placenta. It leads to a fetal systemic inflammatory response that can alter the transcription of neonatal immune genes. We have previously shown that neonatal monocytes gain the activating histone tail modification H3K4me3 at promoter sites of immunologically important genes as development progresses from preterm neonate to adult. In this study, we applied ChIP-seq and RNA-seq to evaluate the impact of chorioamnionitis on the neonatal monocyte H3K4me3 histone modification landscape over the course of fetal and neonatal immune system development. Chorioamnionitis exposure in neonatal monocytes resulted in a net increase in total monocyte H3K4me3, primarily in introns and intergenic regions. Immune gene expression was decreased in chorioamnionitis-exposed monocytes, with the majority of enriched transcripts falling into pathways that are not linked to the immune system. Over half of all neonatal monocyte H3K4me3 peaks, independent of their location, were associated with active gene transcription. Overall, chorioamnionitis exposure resulted in the global remodeling of the neonatal monocyte H3K4me3 landscape and changes in the expression of known immune genes. These changes resulted in a less robust inflammatory response upon exposure to a secondary challenge, which may explain why chorioamnionitis-exposed neonates have an increased risk of sepsis. DATABASE: ChIP-seq data for U30/O30/Term: GEO GSE81957 ChIP-seq data for U30C/O30C/TermC: GEO GSE111873 RNA-seq data for U/L/CU/CL: GEO GSE111927.
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http://dx.doi.org/10.1111/febs.14728DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6326865PMC
January 2019

Murine macrophage chemokine receptor CCR2 plays a crucial role in macrophage recruitment and regulated inflammation in wound healing.

Eur J Immunol 2018 09 26;48(9):1445-1455. Epub 2018 Jun 26.

Department of Surgery, University of Michigan, Ann Arbor, MI, USA.

Macrophages play a critical role in the establishment of a regulated inflammatory response following tissue injury. Following injury, CCR2 monocytes are recruited from peripheral blood to wound tissue, and direct the initiation and resolution of inflammation that is essential for tissue repair. In pathologic states where chronic inflammation prevents healing, macrophages fail to transition to a reparative phenotype. Using a murine model of cutaneous wound healing, we found that CCR2-deficient mice (CCR2 ) demonstrate significantly impaired wound healing at all time points postinjury. Flow cytometry analysis of wounds from CCR2 and WT mice revealed a significant decrease in inflammatory, Ly6C recruited monocyte/macrophages in CCR2 wounds. We further show that wound macrophage inflammatory cytokine production is decreased in CCR2 wounds. Adoptive transfer of mT/mG monocyte/macrophages into CCR2 and CCR2 mice demonstrated that labeled cells on days 2 and 4 traveled to wounds in both CCR2 and CCR2 mice. Further, adoptive transfer of monocyte/macrophages from WT mice restored normal healing, likely through a restored inflammatory response in the CCR2-deficient mice. Taken together, these data suggest that CCR2 plays a critical role in the recruitment and inflammatory response following injury, and that wound repair may be therapeutically manipulated through modulation of CCR2.
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http://dx.doi.org/10.1002/eji.201747400DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6371802PMC
September 2018

Ly6C Blood Monocyte/Macrophage Drive Chronic Inflammation and Impair Wound Healing in Diabetes Mellitus.

Arterioscler Thromb Vasc Biol 2018 05 1;38(5):1102-1114. Epub 2018 Mar 1.

From the Department of Surgery (A.K., A.J., F.M.D., A.D., A.B., A.O., P.K.H., K.A.G.)

Objective: Wound monocyte-derived macrophage plasticity controls the initiation and resolution of inflammation that is critical for proper healing, however, in diabetes mellitus, the resolution of inflammation fails to occur. In diabetic wounds, the kinetics of blood monocyte recruitment and the mechanisms that control in vivo monocyte/macrophage differentiation remain unknown.

Approach And Results: Here, we characterized the kinetics and function of Ly6C [Lin (CD3CD19NK1.1Ter-119) Ly6GCD11b] and Ly6C [Lin (CD3CD19NK1.1Ter-119) Ly6GCD11b] monocyte/macrophage subsets in normal and diabetic wounds. Using flow-sorted -labeled Ly6C monocyte/macrophages, we show Ly6C cells transition to a Ly6C phenotype in normal wounds, whereas in diabetic wounds, there is a late, second influx of Ly6C cells that fail transition to Ly6C. The second wave of Ly6C cells in diabetic wounds corresponded to a spike in MCP-1 (monocyte chemoattractant protein-1) and selective administration of anti-MCP-1 reversed the second Ly6C influx and improved wound healing. To examine the in vivo phenotype of wound monocyte/macrophages, RNA-seq-based transcriptome profiling was performed on flow-sorted Ly6C [LinLy6GCD11b] and Ly6C [LinLy6GCD11b] cells from normal and diabetic wounds. Gene transcriptome profiling of diabetic wound Ly6C cells demonstrated differences in proinflammatory and profibrotic genes compared with controls.

Conclusions: Collectively, these data identify kinetic and functional differences in diabetic wound monocyte/macrophages and demonstrate that selective targeting of CD11bLy6C monocyte/macrophages is a viable therapeutic strategy for inflammation in diabetic wounds.
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http://dx.doi.org/10.1161/ATVBAHA.118.310703DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5920725PMC
May 2018

Neonatal monocytes exhibit a unique histone modification landscape.

Clin Epigenetics 2016 20;8:99. Epub 2016 Sep 20.

Department of Pathology, University of Michigan Medical Center, Ann Arbor, MI 48109 USA.

Background: Neonates have dampened expression of pro-inflammatory cytokines and difficulty clearing pathogens. This makes them uniquely susceptible to infections, but the factors regulating neonatal-specific immune responses are poorly understood. Epigenetics, including histone modifications, can activate or silence gene transcription by modulating chromatin structure and stability without affecting the DNA sequence itself and are potentially modifiable. Histone modifications are known to regulate immune cell differentiation and function in adults but have not been well studied in neonates.

Results: To elucidate the role of histone modifications in neonatal immune function, we performed chromatin immunoprecipitation on mononuclear cells from 45 healthy neonates (gestational ages 23-40 weeks). As gestation approached term, there was increased activating H3K4me3 on the pro-inflammatory , , , and cytokine promoters ( < 0.01) with no change in repressive H3K27me3, suggesting that these promoters in preterm neonates are less open and accessible to transcription factors than in term neonates. Chromatin immunoprecipitation with massively parallel DNA sequencing (ChIP-seq) was then performed to establish the H3K4me3, H3K9me3, H3K27me3, H3K4me1, H3K27ac, and H3K36me3 landscapes in neonatal and adult CD14+ monocytes. As development progressed from neonate to adult, monocytes lost the poised enhancer mark H3K4me1 and gained the activating mark H3K4me3, without a change in additional histone modifications. This decreased H3K4me3 abundance at immunologically important neonatal monocyte gene promoters, including , , , , and was associated with reduced gene expression.

Conclusions: These results provide evidence that neonatal immune cells exist in an epigenetic state that is distinctly different from adults and that this state contributes to neonatal-specific immune responses that leaves them particularly vulnerable to infections.
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http://dx.doi.org/10.1186/s13148-016-0265-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5028999PMC
April 2017

MLL1 and MLL1 fusion proteins have distinct functions in regulating leukemic transcription program.

Cell Discov 2016 17;2:16008. Epub 2016 May 17.

Department of Pathology, University of Michigan, Ann Arbor, MI, USA; Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA.

Mixed lineage leukemia protein-1 (MLL1) has a critical role in human MLL1 rearranged leukemia (MLLr) and is a validated therapeutic target. However, its role in regulating global gene expression in MLLr cells, as well as its interplay with MLL1 fusion proteins remains unclear. Here we show that despite shared DNA-binding and cofactor interacting domains at the N terminus, MLL1 and MLL-AF9 are recruited to distinct chromatin regions and have divergent functions in regulating the leukemic transcription program. We demonstrate that MLL1, probably through C-terminal interaction with WDR5, is recruited to regulatory enhancers that are enriched for binding sites of E-twenty-six (ETS) family transcription factors, whereas MLL-AF9 binds to chromatin regions that have no H3K4me1 enrichment. Transcriptome-wide changes induced by different small molecule inhibitors also highlight the distinct functions of MLL1 and MLL-AF9. Taken together, our studies provide novel insights on how MLL1 and MLL fusion proteins contribute to leukemic gene expression, which have implications for developing effective therapies in the future.
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http://dx.doi.org/10.1038/celldisc.2016.8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4869169PMC
July 2016

Rat Mcs1b is concordant to the genome-wide association-identified breast cancer risk locus at human 5q11.2 and MIER3 is a candidate cancer susceptibility gene.

Cancer Res 2012 Nov 19;72(22):6002-12. Epub 2012 Sep 19.

Center for Genetics and Molecular Medicine, Department of Biochemistry and Molecular Biology, and James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40292, USA.

Low-penetrance alleles associated with breast cancer risk have been identified in population-based studies. Most risk loci contain either no or multiple potential candidate genes. Rat mammary carcinoma susceptibility 1b (Mcs1b) is a quantitative trait locus on RN02 that confers decreased susceptibility when Copenhagen (COP)-resistant alleles are introgressed into a Wistar Furth (WF)-susceptible genome. Five WF.COP congenic lines containing COP RN02 segments were compared. One line developed an average of 3.4 ± 2.0 and 5.5 ± 3.6 mammary carcinomas per rat ± SD when females were Mcs1b-resistant homozygous and Mcs1b heterozygous, respectively. These phenotypes were significantly different from susceptible genotype littermates (7.8 ± 3.1 mean mammary carcinomas per rat ± SD, P = 0.0001 and P = 0.0413, respectively). All other congenic lines tested were susceptible. Thus, Mcs1b was narrowed to 1.8 Mb of RN02 between genetic markers ENSRNOSNP2740854 and g2UL2-27. Mammary gland-graft carcinoma susceptibility assays were used to determine that donor (P = 0.0019), but not recipient Mcs1b genotype (P = 0.9381), was associated with ectopic mammary carcinoma outcome. Rat Mcs1b contains sequence orthologous to human 5q11.2, a breast cancer susceptibility locus identified in multiple genome-wide association studies. Human/rat MAP3K1/Map3k1 and mesoderm induction early response (MIER; MIER3)/MIER3 are within these orthologous segments. We identified MIER3 as a candidate Mcs1b gene based on 4.5-fold higher mammary gland levels of MIER3 transcripts in susceptible compared with Mcs1b-resistant females. These data suggest that the human 5q11.2 breast cancer risk allele marked by rs889312 is mammary gland autonomous, and MIER3 is a candidate breast cancer susceptibility gene.
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http://dx.doi.org/10.1158/0008-5472.CAN-12-0748DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3500408PMC
November 2012

The loss of vacuolar protein sorting 11 (vps11) causes retinal pathogenesis in a vertebrate model of syndromic albinism.

Invest Ophthalmol Vis Sci 2011 May 11;52(6):3119-28. Epub 2011 May 11.

Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.

Purpose: To establish the zebrafish platinum mutant as a model for studying vision defects caused by syndromic albinism diseases such as Chediak-Higashi syndrome, Griscelli syndrome, and Hermansky-Pudlak syndrome (HPS).

Methods: Bulked segregant analysis and candidate gene sequencing revealed that the zebrafish platinum mutation is a single-nucleotide insertion in the vps11 (vacuolar protein sorting 11) gene. Expression of vps11 was determined by RT-PCR and in situ hybridization. Mutants were analyzed for pigmentation defects and retinal disease by histology, immunohistochemistry, and transmission electron microscopy.

Results: Phenocopy and rescue experiments determined that a loss of Vps11 results in the platinum phenotype. Expression of vps11 appeared ubiquitous during zebrafish development, with stronger expression in the developing retina and retinal pigmented epithelium (RPE). Zebrafish platinum mutants exhibited reduced pigmentation in the body and RPE; however, melanophore development, migration, and dispersion occurred normally. RPE, photoreceptors, and inner retinal neurons formed normally in zebrafish platinum mutants. However, a gradual loss of RPE, an absence of mature melanosomes, and the subsequent degradation of RPE/photoreceptor interdigitation was observed.

Conclusions: These data show that Vps11 is not necessary for normal retinal development or initiation of melanin biosynthesis, but is essential for melanosome maturation and healthy maintenance of the RPE and photoreceptors.
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http://dx.doi.org/10.1167/iovs.10-5957DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3109019PMC
May 2011

Permeability of fructose-1,6-bisphosphate in liposomes and cardiac myocytes.

Mol Cell Biochem 2004 Apr;259(1-2):105-14

Department of Biochemistry and Molecular Biology, University of Louisville School of Medicine, Louisville, KY 40292, USA.

Fructose-1,6-bisphosphate (FBP) helps preserve heart and other organs under ischemic conditions. Previous studies indicated that it can be taken up by various cell types. Here we extended observations from our group that FBP could penetrate artificial lipid bilayers and be taken up by cardiac myocytes, comparing the uptake of FBP to that of L-glucose. Using liposomes prepared by the freeze-thaw method, FBP entered about 200-fold slower than L-glucose. For liposomes of either soybean or egg lipids, 50 mM FBP enhanced the permeability of FBP itself, with little effect on general permeability (measured by uptake of L-glucose). In experiments with isolated cardiac myocytes at 21 degrees C, FBP uptake exceeded the uptake of L-glucose by several fold and appeared to equilibrate by 60 min. There was both a saturable component at micromolar levels and a nonsaturable component which dominated at millimolar levels. The saturable component was inhibited by Pi and by other phosphorylated sugars, though with lower affinity than FBP. Both saturable and nonsaturable uptakes were also observed at 3 degrees C. The results indicate that FBP enters myocytes not by simple penetration through the lipid bilayer, but via at least two distinct protein-dependent processes. The uptake could lead to intracellular effects important in hypothermic heart preservation.
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http://dx.doi.org/10.1023/b:mcbi.0000021356.89867.0dDOI Listing
April 2004