Publications by authors named "Steven L Kunkel"

175 Publications

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

NOTCH1 and DLL4 are involved in the human tuberculosis progression and immune response activation.

Tuberculosis (Edinb) 2020 09 8;124:101980. Epub 2020 Aug 8.

Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo - FCFRP/USP, Ribeirão Preto, São Paulo, Brazil. Electronic address:

Tuberculosis (TB) is the leading cause of mortality among infectious diseases worldwide. The study of molecular targets for therapy and diagnosis suggested that Notch signaling is an important pathway for the maintenance of the immune response during Mycobacterium tuberculosis (Mtb) infection. We evaluated the participation of the Notch pathway in the modulation of immune response during Mtb infection, and observed that patients with active TB had increased DLL4 expression in intermediate and non-classic monocytes. Further, patients with moderate and advanced lung injury have higher Notch1 expression in CD4 T cells when compared to patients with a minimal lung injury. When we considered the severity of disease in active TB patients, the expression of the DLL4 in intermediate monocytes and the expression of Notch1 in CD4 T cells are positively correlated with the degree of lung injury. In vitro, PBMCs treated with the Notch pharmacological inhibitor reduced the production of IL-17A and IL-2, whereas anti-hDLL4 treatment promoted a significant increase in TNF-α and phagocytosis. We suggest that Notch1 and DLL4 are associated with immune response activation in human tuberculosis, and can be a novel target to be exploited in the future in the searching of biomarkers.
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http://dx.doi.org/10.1016/j.tube.2020.101980DOI Listing
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

Pneumococcal conjugate vaccine modulates macrophage-mediated innate immunity in pneumonia caused by Streptococcus pneumoniae following influenza.

Microbes Infect 2020 09 17;22(8):312-321. Epub 2020 Jan 17.

Department of Microbiology and Infectious Diseases, Faculty of Medicine, Toho University Graduate School of Medicine, Tokyo, 143-8540, Japan.

Pneumococcal conjugate vaccination (PCV) may prevent influenza-related pneumonia, including Streptococcus pneumoniae pneumonia. To investigate PCV efficacy against secondary pneumococcal pneumonia following influenza, PCV was administered intramuscularly 2 and 5 weeks before S. pneumoniae serotype-3 colonization of murine nasopharynges followed by intranasal challenge with a sublethal dose of influenza A virus. Bacterial and viral loads, including innate immune responses were compared across conditions. PCV vaccination improved the survival of mice with secondary pneumococcal pneumonia and significantly reduced the pulmonary bacterial burden. Increased monocyte/macrophage influx into the lungs, alleviated loss of alveolar macrophages and decreased neutrophil influx into the lungs occurred in PCV-treated mice irrespective of pneumococcal colonization. Higher monocyte chemoattractant protein 1 levels and lower levels of CXCL1, interferon-γ, interleukin-17A, and IL-10, were detected in PCV-treated mice. Additionally, PCV treatment activated the macrophage intracellular killing of S. pneumoniae. Collectively, PCV potentially modulates the host's innate immunity and specific antibodies induction. Macrophage-related innate immunity should be further explored to elucidate the efficacy and mechanisms of PCV versus influenza-related life-threatening diseases.
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http://dx.doi.org/10.1016/j.micinf.2019.12.005DOI Listing
September 2020

Ly6CLo Monocyte/Macrophages are Essential for Thrombus Resolution in a Murine Model of Venous Thrombosis.

Thromb Haemost 2020 Feb 30;120(2):289-299. Epub 2019 Dec 30.

Department of Surgery, Conrad Jobst Vascular Research Laboratories, University of Michigan, Ann Arbor, Michigan, United States.

Venous thrombosis (VT) resolution is a complex process, resembling sterile wound healing. Infiltrating blood-derived monocyte/macrophages (Mo/MΦs) are essential for the regulation of inflammation in tissue repair. These cells differentiate into inflammatory (CD11bLy6C) or proreparative (CD11bLy6C) subtypes. Previous studies have shown that infiltrating Mo/MΦs are important for VT resolution, but the precise roles of different Mo/MΦs subsets are not well understood. Utilizing murine models of stasis and stenosis inferior vena cava thrombosis in concert with a Mo/MΦ depletion model (CD11b-diphtheria toxin receptor [DTR]-expressing mice), we examined the effect of Mo/MΦ depletion on thrombogenesis and VT resolution. In the setting of an 80 to 90% reduction in circulating CD11bMo/MΦs, we demonstrated that Mo/MΦs are not essential for thrombogenesis, with no difference in thrombus size, neutrophil recruitment, or neutrophil extracellular traps found. Conversely, CD11bMo/MΦ are essential for VT resolution. Diphtheria toxoid (DTx)-mediated depletion after thrombus creation depleted primarily CD11bLy6C Mo/MΦs and resulted in larger thrombi. DTx-mediated depletion did not alter CD11bLy6C Mo/MΦ recruitment, suggesting a protective effect of CD11bLy6C Mo/MΦs in VT resolution. Confirmatory Mo/MΦ depletion with clodronate lysosomes showed a similar phenotype, with failure to resolve VT. Adoptive transfer of CD11bLy6C Mo/MΦs into Mo/MΦ-depleted mice reversed the phenotype, restoring normal thrombus resolution. These findings suggest that CD11bLy6C Mo/MΦs are essential for normal VT resolution, consistent with the known proreparative function of this subset, and that further study of Mo/MΦ subsets may identify targets for immunomodulation to accelerate and improve thrombosis resolution.
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http://dx.doi.org/10.1055/s-0039-3400959DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7365023PMC
February 2020

Inhibition of the stem cell factor 248 isoform attenuates the development of pulmonary remodeling disease.

Am J Physiol Lung Cell Mol Physiol 2020 01 20;318(1):L200-L211. Epub 2019 Nov 20.

Department of Pathology, University of Michigan, Ann Arbor, Michigan.

Stem cell factor (SCF) and its receptor c-kit have been implicated in inflammation, tissue remodeling, and fibrosis. Ingenuity Integrated Pathway Analysis of gene expression array data sets showed an upregulation of SCF transcripts in idiopathic pulmonary fibrosis (IPF) lung biopsies compared with tissue from nonfibrotic lungs that are further increased in rapid progressive disease. SCF248, a cleavable isoform of SCF, was abundantly and preferentially expressed in human lung fibroblasts and fibrotic mouse lungs relative to the SCF220 isoform. In fibroblast-mast cell coculture studies, blockade of SCF248 using a novel isoform-specific anti-SCF248 monoclonal antibody (anti-SCF248), attenuated the expression of , and transcripts in cocultured IPF but not normal lung fibroblasts. Administration of anti-SCF248 on days 8 and 12 after bleomycin instillation in mice significantly reduced fibrotic lung remodeling and , , and transcript expression. In addition, bleomycin increased numbers of c-kit+ mast cells, eosinophils, and ILC2 in lungs of mice, whereas they were not significantly increased in anti-SCF248-treated animals. Finally, mesenchymal cell-specific deletion of SCF significantly attenuated bleomycin-mediated lung fibrosis and associated fibrotic gene expression. Collectively, these data demonstrate that SCF is upregulated in diseased IPF lungs and blocking SCF248 isoform significantly ameliorates fibrotic lung remodeling in vivo suggesting that it may be a therapeutic target for fibrotic lung diseases.
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http://dx.doi.org/10.1152/ajplung.00114.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6985874PMC
January 2020

Disruption of Neutrophil Extracellular Traps (NETs) Links Mechanical Strain to Post-traumatic Inflammation.

Front Immunol 2019 24;10:2148. Epub 2019 Oct 24.

Department of Surgery, University of Michigan Medical School, Ann Arbor, MI, United States.

Inflammation after trauma is both critical to normal wound healing and may be highly detrimental when prolonged or unchecked with the potential to impair physiologic healing and promote pathology. Mechanical strain after trauma is associated with impaired wound healing and increased inflammation. The exact mechanisms behind this are not fully elucidated. Neutrophil extracellular traps (NETs), a component of the neutrophil response to trauma, are implicated in a range of pro-inflammatory conditions. In the current study, we evaluated their role in linking movement and inflammation. We found that a link exists between the disruption and amplification of NETs which harbors the potential to regulate the wound's response to mechanical strain, while leaving the initial inflammatory signal necessary for physiologic wound healing intact.
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http://dx.doi.org/10.3389/fimmu.2019.02148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6821718PMC
October 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

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

Attracting Attention: Discovery of IL-8/CXCL8 and the Birth of the Chemokine Field.

J Immunol 2019 01;202(1):3-4

Department of Pathology, University of Michigan, Ann Arbor, MI 48109.

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http://dx.doi.org/10.4049/jimmunol.1801485DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6559818PMC
January 2019

GM-CSF Administration Improves Defects in Innate Immunity and Sepsis Survival in Obese Diabetic Mice.

J Immunol 2019 02 21;202(3):931-942. Epub 2018 Dec 21.

Division of Acute Care Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI 48109;

Sepsis is the leading cause of death in the intensive care unit with an overall mortality rate of 20%. Individuals who are obese and have type 2 diabetes have increased recurrent, chronic, nosocomial infections that worsen the long-term morbidity and mortality from sepsis. Additionally, animal models of sepsis have shown that obese, diabetic mice have lower survival rates compared with nondiabetic mice. Neutrophils are essential for eradication of bacteria, prevention of infectious complications, and sepsis survival. In diabetic states, there is a reduction in neutrophil chemotaxis, phagocytosis, and reactive oxygen species (ROS) generation; however, few studies have investigated the extent to which these deficits compromise infection eradication and mortality. Using a cecal ligation and puncture model of sepsis in lean and in diet-induced obese mice, we demonstrate that obese diabetic mice have decreased "emergency hematopoiesis" after an acute infection. Additionally, both neutrophils and monocytes in obese, diabetic mice have functional defects, with decreased phagocytic ability and a decreased capacity to generate ROS. Neutrophils isolated from obese diabetic mice have decreased transcripts of and , which partially explains the phagocytic dysfunction. Furthermore, we found that exogenous GM-CSF administration improves sepsis survival through enhanced neutrophil and monocytes phagocytosis and ROS generation abilities in obese, diabetic mice with sepsis.
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http://dx.doi.org/10.4049/jimmunol.1800713DOI Listing
February 2019

Role of Chemokine Receptor CCR4 and Regulatory T Cells in Wound Healing of Diabetic Mice.

J Invest Dermatol 2019 05 19;139(5):1161-1170. Epub 2018 Nov 19.

Institute of Biomedical Sciences, Pharmacology and Inflammation Program, Federal University of Rio de Janeiro, Center for Health Sciences, Rio de Janeiro, Rio de Janeiro, Brazil; Institute of Biophysics Carlos Chagas Filho, Immunobiology Program, Federal University of Rio de Janeiro, Center for Health Sciences, Rio de Janeiro, Rio de Janeiro, Brazil. Electronic address:

Wound healing is a well-coordinated process that involves inflammatory mediators and cellular responses; however, if any disturbances are present during this process, tissue repair is impaired. Chronic wounds are one of the serious long-term complications associated with diabetes mellitus. The chemokine receptor CCR4 and its respective ligands, CCL17 and CCL22, are involved in regulatory T cell recruitment and activation in inflamed skin; however, the role of regulatory T cells in wounds is still not clear. Our aim was to investigate the role of CCR4 and regulatory T cells in cutaneous wound healing in diabetic mice. Alloxan-induced diabetic wild- type mice (diabetic) developed wounds that were difficult to heal, differently from CCR4 diabetic mice (CCR4 diabetic), and also from anti-CCL17/22 or anti-CD25-injected diabetic mice that presented with accelerated wound healing and fewer regulatory T cells in the wound bed. Consequently, CCR4 diabetic mice also presented with alteration on T cells population in the wound and draining lymph nodes; on day 14, these mice also displayed an increase of collagen fiber deposition. Still, cytokine levels were decreased in the wounds of CCR4 diabetic mice on day 2. Our data suggest that the receptor CCR4 and regulatory T cells negatively affect wound healing in diabetic mice.
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http://dx.doi.org/10.1016/j.jid.2018.10.039DOI Listing
May 2019

Spred2 Deficiency Exacerbates D-Galactosamine/Lipopolysaccharide -induced Acute Liver Injury in Mice via Increased Production of TNFα.

Sci Rep 2018 01 9;8(1):188. Epub 2018 Jan 9.

Department of Pathology and Experimental Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.

Acute liver injury (ALI) is characterized by hepatocyte damage and inflammation. In the present study, we examined whether the absence of Sprouty-related EVH1-domain-containing protein 2 (Spred2), a negative regulator of the Ras/Raf/ERK/MAPK pathway, influences ALI induced by D-galactosamine (D-GalN) and lipopolysaccharide (LPS). Compared to wild-type mice, Spred2 mice developed exacerbated liver injury represented by enhanced hepatocyte damage and inflammation. Enhanced ERK activation was observed in Spred2-livers, and the MEK/ERK inhibitor U0126 ameliorated ALI. Hepatic tumour necrosis factor α (TNFα) and interleukin (IL)-1β levels were increased in Spred-2-livers, and the neutralization of TNFα dramatically ameliorated ALI, which was associated with decreased levels of endogenous TNFα and IL-1β. When mice were challenged with D-GalN and TNFα, much severer ALI was observed in Spred2 mice with significant increases in endogenous TNFα and IL-1β in the livers. Immunohistochemically, Kupffer cells were found to produce TNFα, and isolated Kupffer cells from Spred2 mice produced significantly higher levels of TNFα than those from wild-type mice after LPS stimulation, which was significantly decreased by U0126. These results suggest that Spred2 negatively regulates D-GalN/LPS-induced ALI under the control of TNFα in Kupffer cells. Spred2 may present a therapeutic target for the treatment of ALI.
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http://dx.doi.org/10.1038/s41598-017-18380-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5760641PMC
January 2018

CXCR3 Signaling Is Required for Restricted Homing of Parenteral Tuberculosis Vaccine-Induced T Cells to Both the Lung Parenchyma and Airway.

J Immunol 2017 10 21;199(7):2555-2569. Epub 2017 Aug 21.

Department of Pathology and Molecular Medicine, McMaster Immunology Research Centre, McMaster University, Hamilton, Ontario L8S 4K1, Canada;

Although most novel tuberculosis (TB) vaccines are designed for delivery via the muscle or skin for enhanced protection in the lung, it has remained poorly understood whether systemic vaccine-induced memory T cells can readily home to the lung mucosa prior to and shortly after pathogen exposure. We have investigated this issue by using a model of parenteral TB immunization and intravascular immunostaining. We find that systemically induced memory T cells are restricted to the blood vessels in the lung, unable to populate either the lung parenchymal tissue or the airway under homeostatic conditions. We further find that after pulmonary TB infection, it still takes many days before such T cells can enter the lung parenchymal tissue and airway. We have identified the acquisition of CXCR3 expression by circulating T cells to be critical for their entry to these lung mucosal compartments. Our findings offer new insights into mucosal T cell biology and have important implications in vaccine strategies against pulmonary TB and other intracellular infections in the lung.
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http://dx.doi.org/10.4049/jimmunol.1700382DOI Listing
October 2017

The STAT4/MLL1 Epigenetic Axis Regulates the Antimicrobial Functions of Murine Macrophages.

J Immunol 2017 09 21;199(5):1865-1874. Epub 2017 Jul 21.

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

Macrophages are critical immune cells for the clearance of microbial pathogens and cellular debris from peripheral tissues. Macrophage inflammatory responses are governed by gene expression patterns, and these patterns are often subject to epigenetic control. Chromatin modifications, such as histone methylation, regulate gene accessibility in macrophages, and macrophage polarization is governed in part by the expression and function of chromatin-modifying enzymes. The histone methyltransferase mixed-lineage leukemia 1 (MLL1) preferentially modifies lysine residue 4 on the unstructured protein tail of histone H3. MLL1 expression and function have been shown to be governed by signal transduction pathways that are activated by inflammatory stimuli, such as NF-κB. Therefore, we sought to investigate the role of MLL1 in mediating macrophage inflammatory responses. Bone marrow-derived macrophages from mice with a targeted MLL1 gene knockout (Lys2-Cre MLL1) exhibited decreased proinflammatory gene expression with concurrent decreases in activating histone methylation. However, MLL1-deficient macrophages also exhibited increased phagocytic and bacterial killing activity in vitro. RNA profiling of MLL1-knockout macrophages identified numerous genes involved with inflammatory responses whose expression was altered in response to TLR ligands or proinflammatory cytokines, including STAT4. STAT4-dependent cytokines, such as type I IFNs were able to drive MLL1 expression in macrophages, and MLL1-knockout macrophages exhibited decreased activating histone methylation in the STAT4 promoter. These results implicate an important role for MLL1-dependent epigenetic regulation of macrophage antimicrobial functions.
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http://dx.doi.org/10.4049/jimmunol.1601272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5568492PMC
September 2017

Macrophage-Mediated Inflammation in Normal and Diabetic Wound Healing.

J Immunol 2017 07;199(1):17-24

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

The healing of cutaneous wounds is dependent on the progression through distinct, yet overlapping phases of wound healing, including hemostasis, inflammation, proliferation, and resolution/remodeling. The failure of these phases to occur in a timely, progressive fashion promotes pathologic wound healing. The macrophage (MΦ) has been demonstrated to play a critical role in the inflammatory phase of tissue repair, where its dynamic plasticity allows this cell to mediate both tissue-destructive and -reparative functions. The ability to understand and control both the initiation and the resolution of inflammation is critical for treating pathologic wound healing. There are now a host of studies demonstrating that metabolic and epigenetic regulation of gene transcription can influence MΦ plasticity in wounds. In this review, we highlight the molecular and epigenetic factors that influence MΦ polarization in both physiologic and pathologic wound healing, with particular attention to diabetic wounds.
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http://dx.doi.org/10.4049/jimmunol.1700223DOI Listing
July 2017

Evaluation of Salivary Cytokines for Diagnosis of both Trauma-Induced and Genetic Heterotopic Ossification.

Front Endocrinol (Lausanne) 2017 24;8:74. Epub 2017 Apr 24.

Burn/Wound and Regenerative Medicine Laboratory, Department of Surgery, University of Michigan, Ann Arbor, MI, USA.

Purpose: Heterotopic ossification (HO) occurs in the setting of persistent systemic inflammation. The identification of reliable biomarkers can serve as an early diagnostic tool for HO, especially given the current lack of effective treatment strategies. Although serum biomarkers have great utility, they can be inappropriate or ineffective in traumatic acute injuries and in patients with fibrodysplasia ossificans progressiva (FOP). Therefore, the goal of this study is to profile the cytokines associated with HO using a different non-invasive source of biomarkers.

Methods: Serum and saliva were collected from a model of trauma-induced HO (tHO) with hind limb Achilles' tenotomy and dorsal burn injury at indicated time points (pre-injury, 48 h, 1 week, and 3 weeks post-injury) and a genetic non-trauma HO model ( ). Samples were analyzed for 27 cytokines using the Bio-Plex assay. Histologic evaluation was performed in mice and at 48 h and 1 week post-injury in burn tenotomy mice. The mRNA expression levels of these cytokines at the tenotomy site were also quantified with quantitative real-time PCR. Pearson correlation coefficient was assessed between saliva and serum.

Results: Levels of TNF-α and IL-1β peaked at 48 h and 1 week post-injury in the burn/tenotomy cohort, and these values were significantly higher when compared with both uninjured ( < 0.01,  < 0.03) and burn-only mice ( < 0.01,  < 0.01). Immunofluorescence staining confirmed enhanced expression of IL-1β, TNF-α, and MCP-1 at the tenotomy site 48 h after injury. Monocyte chemoattractant protein-1 (MCP-1) and VEGF was detected in saliva showing elevated levels at 1 week post-injury in our tHO model when compared with both uninjured ( < 0.001,  < 0.01) and burn-only mice ( < 0.005,  < 0.01). The Pearson correlation between serum MCP-1 and salivary MCP-1 was statistically significant ( = 0.9686,  < 0.001) Similarly, the Pearson correlation between serum VEGF and salivary VEGF was statistically significant ( = 0.9709,  < 0.05).

Conclusion: In this preliminary study, we characterized the diagnostic potential of specific salivary cytokines that may serve as biomarkers for an early-stage diagnosis of HO. This study identified two candidate biomarkers for further study and suggests a novel method for diagnosis in the context of current difficult diagnosis and risks of current diagnostic methods in certain patients.
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http://dx.doi.org/10.3389/fendo.2017.00074DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5401868PMC
April 2017

Enhancement of macrophage inflammatory responses by CCL2 is correlated with increased miR-9 expression and downregulation of the ERK1/2 phosphatase Dusp6.

Cell Immunol 2017 04 22;314:63-72. Epub 2017 Feb 22.

Department of Pathology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA. Electronic address:

Macrophage polarization plays a central role in both protective immunity and immunopathology. While the role of cytokines in driving macrophage polarization is well characterized, less is understood about the role of chemokines. The purpose of this study was to determine if CC chemokine 2 (CCL2/MCP1) could influence macrophage polarization in response to subsequent activation with cytokines and microbial products. Treatment of bone marrow-derived macrophages with CCL2 alone did not result in increased expression of either classical or alternatively-activated macrophage genes as compared to standard skewing cytokines or Toll-like receptor agonists. However, subsequent stimulation of CCL2 pre-treated macrophages with classical activation stimuli resulted in enhanced expression of genes associated with classical activation. This enhancement correlated with increased phosphorylation of ERK1/2 kinases, a decrease in expression of the ERK phosphatase Dusp6 and enhanced expression of miR-9. These results indicate that CCL2 supports the classical activation of macrophages, with miR-9 mediated down-regulation of Dusp6 and enhanced ERK-mediated signal transduction possibly mediating this enhanced pro-inflammatory gene expression.
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http://dx.doi.org/10.1016/j.cellimm.2017.02.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5425952PMC
April 2017

Systemic Expression of Notch Ligand Delta-Like 4 during Mycobacterial Infection Alters the T Cell Immune Response.

Front Immunol 2016 24;7:527. Epub 2016 Nov 24.

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

The Notch ligand delta-like 4 (DLL4) is known to fine-tune the CD4 T cell cytokine response. DLL4 is expressed on the surface of antigen-presenting cells (APCs) in a MyD88-dependent manner. We found that DLL4 expression was upregulated on bone marrow progenitor cells and APCs in mice infected with BCG . Transfer of DLL4 progenitor cells from infected hosts resulted in an increase DLL4 myeloid cells in the spleen, indicating that expression of the gene is propagated throughout hematopoiesis. We also found an increase in DLL4 monocytes from individuals who were infected with . In latent individuals, DLL4 expression correlated with increased cytokine production from T cells in response to PPD stimulation. Finally, antibody blockade of DLL4 reduced T cell cytokine production from naïve T cells stimulated with antigen. These results demonstrate that the Notch ligand DLL4 can influence T cell cytokine production in both humans and mice, and further reveal that expression of DLL4 is upregulated on early hematopoietic progenitors in response to chronic mycobacterial infection. These data suggest that widespread DLL4 expression may occur as a result of mycobacterial infection, and that this expression may alter CD4 T cell responses to both previously encountered and novel antigens.
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http://dx.doi.org/10.3389/fimmu.2016.00527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5121470PMC
November 2016

Intact Toll-like receptor 9 signaling in neutrophils modulates normal thrombogenesis in mice.

J Vasc Surg 2016 Nov 23;64(5):1450-1458.e1. Epub 2015 Oct 23.

Department of Vascular Surgery, University of Michigan Medical School, Ann Arbor, Mich. Electronic address:

Background: Deletion of Toll-like receptor 9 (Tlr9) signaling, which is important for sterile inflammatory processes, results in impaired resolution of venous thrombosis (VT) in mice. The purpose of this study was to determine if deletion of Tlr9 affected sterile necrosis, apoptosis, and neutrophil extracellular trap (NET) production in VT.

Methods: Stasis and nonstasis murine models of VT were used in wild-type (WT) and Tlr9 mice, with assessment of thrombus size and determination of NETs, necrosis, and apoptosis markers. Anti-polymorphonuclear neutrophil (PMN) and antiplatelet antibody strategies were used to determine the cellular roles and their roles in WT and Tlr9 mice.

Results: At 2 days, stasis thrombi in Tlr9 mice were 62% larger (n = 6-10), with 1.4-fold increased uric acid levels, 1.7-fold more apoptotic cells, 2-fold increased citrullinated histones, 2-fold increased peptidylarginine deiminase 4 (PAD4), and 1.5-fold increased elastase and a 2.4-fold reduction in tissue factor pathway inhibitor compared with WT mice (all n = 4-7; P < .05). In contrast, the sizes of nonstasis thrombi were not significantly different in Tlr9 mice (n = 4-6), and they did not have elevated necrosis or NET markers. Stasis thrombus size was not reduced at the 2-day time point in WT or Tlr9 mice that received treatment with deoxyribonuclease I or in PAD4 mice, which are incapable of forming NETs. In Tlr9 mice undergoing PMN depletion (n = 8-10), stasis thrombus size was reduced 18% and was associated with 29-fold decreased citrullinated histones, 1.3-fold decreased elastase, and 1.5-fold increased tissue factor pathway inhibitor (all n = 6; P < .05). Last, platelet depletion (>90% reduction) did not significantly reduce stasis thrombus size in Tlr9 mice.

Conclusions: These data suggest that the thrombogenic model affects Tlr9 thrombogenic mechanisms and that functional Tlr9 signaling in PMNs, but not in platelets or NETs, is an important mechanism in early stasis experimental venous thrombogenesis.
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http://dx.doi.org/10.1016/j.jvs.2015.08.070DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4834067PMC
November 2016

Double-Stranded RNA Interacts With Toll-Like Receptor 3 in Driving the Acute Inflammatory Response Following Lung Contusion.

Crit Care Med 2016 Nov;44(11):e1054-e1066

1Department of Surgery, University of Michigan, Ann Arbor, MI. 2Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI. 3Department of Pathology, University of Michigan, Ann Arbor, MI. 4Department of Chemistry, University of Michigan, Ann Arbor, MI. 5Department of Medicine, Cedar Sinai Medical Center, Los Angeles, CA.

Objectives: Lung contusion is a major risk factor for the development of acute respiratory distress syndrome. We set to determine the role of toll-like receptor 3 and the binding of double-stranded RNA in the pathogenesis of sterile injury following lung contusion.

Design: Toll-like receptor 3 expression was analyzed in postmortem lung samples from patients with lung contusion. Unilateral lung contusion was induced in toll-like receptor 3 (-/-), TIR-domain-containing adapter-inducing interferon-β (-/-), and wild-type mice. Subsequently, lung injury and inflammation were evaluated. Apoptotic indices, phagocytic activity, and phenotypic characterization of the macrophages were determined. Double-stranded RNA in bronchoalveolar lavage and serum samples following lung contusion was measured. A toll-like receptor 3/double-stranded RNA ligand inhibitor was injected into wild-type mice prior to lung contusion.

Measurements And Main Results: Toll-like receptor 3 expression was higher in patients and wild-type mice with lung contusion. The degree of lung injury, inflammation, and macrophage apoptosis was reduced in toll-like receptor 3 (-/-), TIR-domain-containing adapter-inducing interferon-β (-/-), and wild-type mice with toll-like receptor 3 antibody neutralization. Alveolar macrophages from toll-like receptor 3 (-/-) mice had a lower early apoptotic index, a predominant M2 phenotype and increased surface translocation of toll-like receptor 3 from the endosome to the surface. When compared with viral activation pathways, lung injury in lung contusion demonstrated increased p38 mitogen-activated protein kinases, extracellular signal-regulated kinase 1/2 phosphorylation with inflammasome activation without a corresponding increase in nuclear factor-κB or type-1 interferon production. Additionally, pretreatment with toll-like receptor 3/double-stranded RNA ligand inhibitor led to a reduction in injury, inflammation, and macrophage apoptosis.

Conclusions: We conclude that the interaction of double-stranded RNA from injured cells with toll-like receptor 3 drives the acute inflammatory response following lung contusion.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5069108PMC
http://dx.doi.org/10.1097/CCM.0000000000001879DOI Listing
November 2016

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

Histone Deacetylase Inhibition Protects Mice Against Lethal Postinfluenza Pneumococcal Infection.

Crit Care Med 2016 10;44(10):e980-7

1Division of Pulmonary Medicine, Department of Medicine, Keio University School of Medicine, Tokyo, Japan.2Department of Immunology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan.3Second Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki, Japan.4Department of Infectious Diseases, Keio University School of Medicine, Tokyo, Japan.5Center for Infectious Diseases and Infection Control, Keio University School of Medicine, Tokyo, Japan.6Department of Pathology, University of Michigan Medical School, Ann Arbor, MI.

Objectives: Secondary bacterial pneumonia following influenza virus infection is associated with high mortality, but the mechanism is largely unknown. Epigenetic gene regulation appears to play key roles in innate and adaptive immunity. We hypothesized that histone acetylation, a major epigenetic mechanism associated with transcriptionally active chromatin, might contribute to the poor outcome of postinfluenza pneumonia.

Design: Prospective experimental study.

Setting: University research laboratory.

Subjects: C57BL/6 male mice.

Interventions: Mice were infected intranasally with 1.0 × 10 colony-forming units of Streptococcus pneumoniae, 7 days after intranasal inoculation with five plaque-forming units of influenza virus A/H1N1/PR8/34. The mice were intraperitoneally injected with the histone deacetylase inhibitor trichostatin A (1 mg/kg) or vehicle once a day from 1 hour after pneumococcal infection throughout the course of the experiment. The primary outcome was survival rate.

Measurements And Main Results: Trichostatin A significantly suppressed histone deacetylase activity and significantly improved the survival rate of mice (56.3%) after postinfluenza pneumococcal infection when compared with vehicle-treated mice (20.0%), which was associated with a significant decrease in the total cell count of the bronchoalveolar lavage fluid. The interleukin-1β level in the serum and the number of natural killer cells in the lungs were significantly lower in the trichostatin A-treated group.

Conclusions: The histone deacetylase inhibitor trichostatin A protects mice against postinfluenza pneumonia possibly through multiple factors, including decreasing local cell recruitment into the lungs and suppressing systemic inflammation.
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http://dx.doi.org/10.1097/CCM.0000000000001821DOI Listing
October 2016

IL-36γ is secreted in microparticles and exosomes by lung macrophages in response to bacteria and bacterial components.

J Leukoc Biol 2016 08 10;100(2):413-21. Epub 2016 Feb 10.

Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine.

Interleukin-36 is a family of novel interleukin-1-like proinflammatory cytokines that are highly expressed in epithelial tissues and several myeloid-derived cell types. Like those of classic interleukin-1 cytokines, the secretion mechanisms of interleukin-36 are not well understood. Interleukin-36γ secretion in dermal epithelial cells requires adenosine 5'-triphosphate, which suggests a nonclassical mechanism of secretion. In this study, murine pulmonary macrophages and human alveolar macrophages were treated with recombinant pathogen-associated molecular patterns (intact bacteria: Klebsiella pneumoniae or Streptococcus pneumoniae). Cell lysates were analyzed for messenger ribonucleic acid by quantitative real-time polymerase chain reaction, and conditioned medium was analyzed for interleukin-36γ by enzyme-linked immunosorbent assay, with or without sonication. In addition, conditioned medium was ultracentrifuged at 25,000 g and 100,000 g, to isolate microparticles and exosomes, respectively, and interleukin-36γ protein was assessed in each fraction by Western blot analysis. Interleukin-36γ mRNA was induced in both murine and human lung macrophages by a variety of pathogen-associated molecular patterns, as well as heat-killed and live Klebsiella pneumoniae and Streptococcus pneumoniae, and induction occurred in a myeloid differentiation response gene 88-dependent manner. Secretion of interleukin-36γ protein was enhanced by adenosine 5'-triphosphate. Furthermore, extracellular interleukin-36γ protein detection was markedly enhanced by sonication to disrupt membrane-bound structures. Interleukin-36γ protein was detected by Western blot in microparticles and exosome fractions isolated by ultracentrifugation. Interleukin-36γ was induced and secreted from lung macrophages in response to Gram-negative and -positive bacterial stimulation. The results suggest that interleukin-36γ is secreted in a non-Golgi-dependent manner by lung macrophages in response to Gram-positive and -negative bacterial challenge.
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http://dx.doi.org/10.1189/jlb.4A0315-087RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4945350PMC
August 2016

Sprouty-Related Ena/Vasodilator-Stimulated Phosphoprotein Homology 1-Domain-Containing Protein-2 Critically Regulates Influenza A Virus-Induced Pneumonia.

Crit Care Med 2016 07;44(7):e530-43

1Department of Pathology and Experimental Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan. 2Department of Immunology, Nara Medical University, Kashihara, Japan. 3Department of Virology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan. 4Department of Pediatrics, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan. 5Department of Pathology, University of Michigan Medical School, Ann Arbor, MI.

Objectives: Influenza A virus causes acute respiratory infections that induce annual epidemics and occasional pandemics. Although a number of studies indicated that the virus-induced intracellular signaling events are important in combating influenza virus infection, the mechanism how specific molecule plays a critical role among various intracellular signaling events remains unknown. Raf/MEK/extracellular signal-regulated kinase cascade is one of the key signaling pathways during influenza virus infection, and the Sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein has recently been identified as a negative regulator of Raf-dependent extracellular signal-regulated kinase activation. Here, we examined the role of Raf/MEK/extracellular signal-regulated kinase cascade through sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein in influenza A viral infection because the expression of sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein was significantly enhanced in human influenza viral-induced pneumonia autopsy samples.

Design: Prospective animal trial.

Setting: Research laboratory.

Subjects: Wild-type and sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein-2 knockout mice inoculated with influenza A.

Interventions: Wild-type or sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein-2 knockout mice were infected by intranasal inoculation of influenza A (A/PR/8). An equal volume of phosphate-buffered saline was inoculated intranasally into mock-infected mice.

Measurements And Main Results: Influenza A infection of sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein-2 knockout mice led to higher mortality with greater viral load, excessive inflammation, and enhanced cytokine production than wild-type mice. Administration of MEK inhibitor, U0126, improved mortality and reduced both viral load and cytokine levels. Furthermore, bone marrow chimeras indicated that influenza A-induced lung pathology was most severe when sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein-2 expression was lacking in nonimmune cell populations. Furthermore, microarray analysis revealed knockdown of sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein-2 led to enhanced phosphatidylinositol 3-kinase signaling pathway, resulting that viral clearance was regulated by sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein-2 expression through the phosphatidylinositol 3-kinase signaling pathway in murine lung epithelial cells.

Conclusions: These data support an important function of sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein-2 in controlling influenza virus-induced pneumonia and viral replication. Sprouty-related Ena/vasodilator-stimulated phosphoprotein homology 1-domain-containing protein-2 may be a novel therapeutic target for controlling the immune response against influenza influenza A virus infection.
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http://dx.doi.org/10.1097/CCM.0000000000001562DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4911260PMC
July 2016

Type I Interferon Induced Epigenetic Regulation of Macrophages Suppresses Innate and Adaptive Immunity in Acute Respiratory Viral Infection.

PLoS Pathog 2015 Dec 28;11(12):e1005338. Epub 2015 Dec 28.

Department of Pathology, University of Michigan, Ann Arbor, Michigan, United States of America.

Influenza A virus (IAV) is an airborne pathogen that causes significant morbidity and mortality each year. Macrophages (Mϕ) are the first immune population to encounter IAV virions in the lungs and are required to control infection. In the present study, we explored the mechanism by which cytokine signaling regulates the phenotype and function of Mϕ via epigenetic modification of chromatin. We have found that type I interferon (IFN-I) potently upregulates the lysine methyltransferase Setdb2 in murine and human Mϕ, and in turn Setdb2 regulates Mϕ-mediated immunity in response to IAV. The induction of Setdb2 by IFN-I was significantly impaired upon inhibition of the JAK-STAT signaling cascade, and chromatin immunoprecipitation revealed that both STAT1 and interferon regulatory factor 7 bind upstream of the transcription start site to induce expression. The generation of Setdb2LacZ reporter mice revealed that IAV infection results in systemic upregulation of Setdb2 in myeloid cells. In the lungs, alveolar Mϕ expressed the highest level of Setdb2, with greater than 70% lacZ positive on day 4 post-infection. Silencing Setdb2 activity in Mϕ in vivo enhanced survival in lethal IAV infection. Enhanced host protection correlated with an amplified antiviral response and less obstruction to the airways. By tri-methylating H3K9, Setdb2 silenced the transcription of Mx1 and Isg15, antiviral effectors that inhibit IAV replication. Accordingly, a reduced viral load in knockout mice on day 8 post-infection was linked to elevated Isg15 and Mx1 transcript in the lungs. In addition, Setdb2 suppressed the expression of a large number of other genes with proinflammatory or immunomodulatory function. This included Ccl2, a chemokine that signals through CCR2 to regulate monocyte recruitment to infectious sites. Consistently, knockout mice produced more CCL2 upon IAV infection and this correlated with a 2-fold increase in the number of inflammatory monocytes and alveolar Mϕ in the lungs. Finally, Setdb2 expression by Mϕ suppressed IL-2, IL-10, and IFN-γ production by CD4+ T cells in vitro, as well as proliferation in IAV-infected lungs. Collectively, these findings identify Setdb2 as a novel regulator of the immune system in acute respiratory viral infection.
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http://dx.doi.org/10.1371/journal.ppat.1005338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4692439PMC
December 2015