Publications by authors named "Evelyn Kurt-Jones"

99 Publications

Expression of SARS coronavirus 1 spike protein from a herpesviral vector induces innate immune signaling and neutralizing antibody responses.

Virology 2021 Apr 21;559:165-172. Epub 2021 Apr 21.

Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA. Electronic address:

SARS coronavirus 1 (SARS-CoV-1) causes a respiratory infection that can lead to acute respiratory distress characterized by inflammation and high levels of cytokines in the lung tissue. In this study we constructed a herpes simplex virus 1 replication-defective mutant vector expressing SARS-CoV-1 spike protein as a potential vaccine vector and to probe the effects of spike protein on host cells. The spike protein expressed from this vector is functional in that it localizes to the surface of infected cells and induces fusion of ACE2-expressing cells. In immunized mice, the recombinant vector induced antibodies that bind to spike protein in an ELISA assay and that show neutralizing activity. The spike protein expressed from this vector can induce the expression of cytokines in an ACE2-independent, MyD88-dependent process. These results argue that the SARS-CoV-1 spike protein intrinsically activates signaling pathways that induce cytokines and contribute directly to the inflammatory process of SARS.
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http://dx.doi.org/10.1016/j.virol.2021.04.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8058630PMC
April 2021

Astrocyte- and Neuron-Derived CXCL1 Drives Neutrophil Transmigration and Blood-Brain Barrier Permeability in Viral Encephalitis.

Cell Rep 2020 09;32(11):108150

Center for Immunology and Inflammatory Diseases, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA. Electronic address:

Herpes simplex virus (HSV)-1 encephalitis has significant morbidity partly because of an over-exuberant immune response characterized by leukocyte infiltration into the brain and increased blood-brain barrier (BBB) permeability. Determining the role of specific leukocyte subsets and the factors that mediate their recruitment into the brain is critical to developing targeted immune therapies. In a murine model, we find that the chemokines CXCL1 and CCL2 are induced in the brain following HSV-1 infection. Ccr2 (CCL2 receptor)-deficient mice have reduced monocyte recruitment, uncontrolled viral replication, and increased morbidity. Contrastingly, Cxcr2 (CXCL1 receptor)-deficient mice exhibit markedly reduced neutrophil recruitment, BBB permeability, and morbidity, without influencing viral load. CXCL1 is produced by astrocytes in response to HSV-1 and by astrocytes and neurons in response to IL-1α, and it is the critical ligand required for neutrophil transendothelial migration, which correlates with BBB breakdown. Thus, the CXCL1-CXCR2 axis represents an attractive therapeutic target to limit neutrophil-mediated morbidity in HSV-1 encephalitis.
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http://dx.doi.org/10.1016/j.celrep.2020.108150DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7548103PMC
September 2020

Alcohol-induced adipose tissue macrophage phenotypic switching is independent of myeloid Toll-like receptor 4 expression.

Am J Physiol Cell Physiol 2019 10 3;317(4):C687-C700. Epub 2019 Jul 3.

Graduate School of Biomedical Sciences, University of Massachusetts Medical School, Worcester, Massachusetts.

Alcoholic liver disease results from a combination of immune and metabolic pathogenic events. In addition to liver injury, chronic alcohol consumption also causes adipose tissue inflammation. The specific immune mechanisms that drive this process are unknown. Here, we sought to determine the role of the innate immune receptor Toll-like receptor 4 (TLR4) in alcohol-induced adipose tissue inflammation. Using a model of chronic, multiple-binge alcohol exposure, we showed that alcohol-mediated accumulation of proinflammatory adipose tissue macrophages was absent in global TLR4 knockout mice. Proinflammatory macrophage accumulation did not depend on macrophage TLR4 expression; LysMCre-driven deletion of from myeloid cells did not affect circulating endotoxin or the accumulation of M1 macrophages in adipose tissue following alcohol exposure. Proinflammatory cytokine/chemokine production in the adipose stromal vascular fraction also occurred independently of TLR4. Finally, the levels of other adipose immune cells, such as dendritic cells, neutrophils, B cells, and T cells, were modulated by chronic, multiple-binge alcohol and the presence of TLR4. Together, these data indicate that TLR4 expression on cells, other than myeloid cells, is important for the alcohol-induced increase in proinflammatory adipose tissue macrophages.
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http://dx.doi.org/10.1152/ajpcell.00276.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6850994PMC
October 2019

The role of platelets in mediating a response to human influenza infection.

Nat Commun 2019 04 16;10(1):1780. Epub 2019 Apr 16.

Department of Medicine, Division of Cardiovascular Medicine, 368 Plantation Street, Worcester, MA, 01605, USA.

Influenza infection increases the incidence of myocardial infarction but the reason is unknown. Platelets mediate vascular occlusion through thrombotic functions but are also recognized to have immunomodulatory activity. To determine if platelet processes are activated during influenza infection, we collected blood from 18 patients with acute influenza infection. Microscopy reveals activated platelets, many containing viral particles and extracellular-DNA associated with platelets. To understand the mechanism, we isolate human platelets and treat them with influenza A virus. Viral-engulfment leads to C3 release from platelets as a function of TLR7 and C3 leads to neutrophil-DNA release and aggregation. TLR7 specificity is confirmed in murine models lacking the receptor, and platelet depletion models support platelet-mediated C3 and neutrophil-DNA release post-influenza infection. These findings demonstrate that the initial intrinsic defense against influenza is mediated by platelet-neutrophil cross-communication that tightly regulates host immune and complement responses but can also lead to thrombotic vascular occlusion.
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http://dx.doi.org/10.1038/s41467-019-09607-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6467905PMC
April 2019

A Disintegrin and Metalloproteinase 9 Domain (ADAM9) Is a Major Susceptibility Factor in the Early Stages of Encephalomyocarditis Virus Infection.

mBio 2019 02 5;10(1). Epub 2019 Feb 5.

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA

Encephalomyocarditis virus (EMCV) is a picornavirus that produces lytic infections in murine and human cells. Employing a genome-wide CRISPR-Cas9 knockout screen to find host factors required for EMCV infection, we identified a role for ADAM9 in EMCV infection. CRISPR-mediated deletion of ADAM9 in multiple human cell lines rendered the cells highly resistant to EMCV infection and cell death. Primary fibroblasts from ADAM9 KO mice were also strongly resistant to EMCV infection and cell death. In contrast, ADAM9 KO and WT cells were equally susceptible to infection with other viruses, including the picornavirus Coxsackie virus B. ADAM9 KO cells failed to produce viral progeny when incubated with EMCV. However, bypassing EMCV entry into cells through delivery of viral RNA directly to the cytosol yielded infectious EMCV virions from ADAM9 KO cells, suggesting that ADAM9 is not required for EMCV replication post-entry. These findings establish that ADAM9 is required for the early stage of EMCV infection, likely for virus entry or viral genome delivery to the cytosol. Viral myocarditis is a leading cause of death in the United States, contributing to numerous unexplained deaths in people ≤35 years old. Enteroviruses contribute to many cases of human myocarditis. Encephalomyocarditis virus (EMCV) infection causes viral myocarditis in rodent models, but its receptor requirements have not been fully identified. CRISPR-Cas9 screens can identify host dependency factors essential for EMCV infection and enhance our understanding of key events that follow viral infection, potentially leading to new strategies for preventing viral myocarditis. Using a CRISPR-Cas9 screen, we identified isintegrin nd etalloproteinase 9 domain (ADAM9) as a major factor required for the early stages of EMCV infection in both human and murine infection.
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http://dx.doi.org/10.1128/mBio.02734-18DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6428755PMC
February 2019

Micro RNAs from DNA Viruses are Found Widely in Plasma in a Large Observational Human Population.

Sci Rep 2018 04 23;8(1):6397. Epub 2018 Apr 23.

University of Massachusetts Medical School, Department of Medicine, Division of Cardiovascular Medicine, Worcester, MA, 01605, USA.

Viral infections associate with disease risk and select families of viruses encode miRNAs that control an efficient viral cycle. The association of viral miRNA expression with disease in a large human population has not been previously explored. We sequenced plasma RNA from 40 participants of the Framingham Heart Study (FHS, Offspring Cohort, Visit 8) and identified 3 viral miRNAs from 3 different human Herpesviridae. These miRNAs were mostly related to viral latency and have not been previously detected in human plasma. Viral miRNA expression was then screened in the plasma of 2763 participants of the remaining cohort utilizing high-throughput RT-qPCR. All 3 viral miRNAs associated with combinations of inflammatory or prothrombotic circulating biomarkers (sTNFRII, IL-6, sICAM1, OPG, P-selectin) but did not associate with hypertension, coronary heart disease or cancer. Using a large observational population, we demonstrate that the presence of select viral miRNAs in the human circulation associate with inflammatory biomarkers and possibly immune response, but fail to associate with overt disease. This study greatly extends smaller singular observations of viral miRNAs in the human circulation and suggests that select viral miRNAs, such as those for latency, may not impact disease manifestation.
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http://dx.doi.org/10.1038/s41598-018-24765-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913337PMC
April 2018

Cyclic GMP-AMP Synthase Is the Cytosolic Sensor of Genomic DNA and Activates Type I IFN in Malaria.

J Immunol 2018 01 6;200(2):768-774. Epub 2017 Dec 6.

Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605;

Innate immune receptors have a key role in the sensing of malaria and initiating immune responses. As a consequence of infection, systemic inflammation emerges and is directly related to signs and symptoms during acute disease. We have previously reported that plasmodial DNA is the primary driver of systemic inflammation in malaria, both within the phagolysosome and in the cytosol of effector cells. In this article, we demonstrate that genomic DNA delivered to the cytosol of human monocytes binds and activates cyclic GMP-AMP synthase (cGAS). Activated cGAS synthesizes 2'3'-cGAMP, which we subsequently can detect using liquid chromatography-tandem mass spectrometry. 2'3'-cGAMP acts as a second messenger for STING activation and triggers TBK1/IRF3 activation, resulting in type I IFN production in human cells. This induction of type I IFN was independent of IFI16. Access of DNA to the cytosolic compartment is mediated by hemozoin, because incubation of purified malaria pigment with DNase abrogated IFN-β induction. Collectively, these observations implicate cGAS as an important cytosolic sensor of genomic DNA and reveal the role of the cGAS/STING pathway in the induction of type I IFN in response to malaria parasites.
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http://dx.doi.org/10.4049/jimmunol.1701048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5912257PMC
January 2018

Innate Immune Mechanisms and Herpes Simplex Virus Infection and Disease.

Adv Anat Embryol Cell Biol 2017 ;223:49-75

Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA.

Innate immune responses play a major role in the control of herpes simplex virus (HSV) infections, and a multiplicity of mechanisms have emerged as a result of human evolution to sense and respond to HSV infections. HSV in turn has evolved a number of ways to evade immune detection and to blunt human innate immune responses. In this review, we summarize the major host innate immune mechanisms and the HSV evasion mechanisms that have evolved. We further discuss how disease can result if this equilibrium between virus and host response is disrupted.
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http://dx.doi.org/10.1007/978-3-319-53168-7_3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7254490PMC
June 2018

miR-718 represses proinflammatory cytokine production through targeting phosphatase and tensin homolog (PTEN).

J Biol Chem 2017 04 16;292(14):5634-5644. Epub 2017 Feb 16.

From the Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts 01605 and.

Bacterial sepsis involves a complex interaction between the host immune response and bacterial LPS. LPS binds Toll-like receptor (TLR) 4, which leads to the release of proinflammatory cytokines that are essential for a potent innate immune response against pathogens. The innate immune system is tightly regulated, as excessive inflammation can lead to organ failure and death. MicroRNAs have recently emerged as important regulators of the innate immune system. Here we determined the function of miR-718, which is conserved across mammals and overlaps with the 5' UTR of the interleukin 1 receptor-associated kinase () gene. As IRAK1 is a key component of innate immune signaling pathways that are downstream of most TLRs, we hypothesized that miR-718 helps regulate the innate immune response. Activation of TLR4, but not TLR3, induced the expression of miR-718 in macrophages. miR-718 expression was also induced in the spleens of mice upon LPS injection. miR-718 modulates PI3K/Akt signaling by directly down-regulating phosphatase and tensin homolog (PTEN), thereby promoting phosphorylation of Akt, which leads to a decrease in proinflammatory cytokine production. Phosphorylated Akt induces let-7e expression, which, in turn, down-regulates TLR4 and further diminishes TLR4-mediated proinflammatory signals. Decreased miR-718 expression is associated with bacterial burden during infection and alters the infection dynamics of Furthermore, miR-718 regulates the induction of LPS tolerance in macrophages. We propose a role for miR-718 in controlling TLR4 signaling and inflammatory cytokine signaling through a negative feedback regulation loop involving down-regulation of TLR4, IRAK1, and NF-κB.
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http://dx.doi.org/10.1074/jbc.M116.749325DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5392559PMC
April 2017

Endoplasmic Reticulum Stress-induced Hepatocellular Death Pathways Mediate Liver Injury and Fibrosis via Stimulator of Interferon Genes.

J Biol Chem 2016 Dec 3;291(52):26794-26805. Epub 2016 Nov 3.

From the Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605

Fibrosis, driven by inflammation, marks the transition from benign to progressive stages of chronic liver diseases. Although inflammation promotes fibrogenesis, it is not known whether other events, such as hepatocyte death, are required for the development of fibrosis. Interferon regulatory factor 3 (IRF3) regulates hepatocyte apoptosis and production of type I IFNs. In the liver, IRF3 is activated via Toll-like receptor 4 (TLR4) signaling or the endoplasmic reticulum (ER) adapter, stimulator of interferon genes (STING). We hypothesized that IRF3-mediated hepatocyte death is an independent determinant of chemically induced liver fibrogenesis. To test this, we performed acute or chronic CCl administration to WT and IRF3-, Toll/Interleukin-1R (TIR) domain-containing adapter-inducing interferon-β (TRIF)-, TRIF-related adaptor molecule (TRAM)-, and STING-deficient mice. We report that acute CCl administration to WT mice resulted in early ER stress, activation of IRF3, and type I IFNs, followed by hepatocyte apoptosis and liver injury, accompanied by liver fibrosis upon repeated administration of CCl Deficiency of IRF3 or STING prevented hepatocyte death and fibrosis both in acute or chronic CCl In contrast, mice deficient in type I IFN receptors or in TLR4 signaling adaptors, TRAM or TRIF, upstream of IRF3, were not protected from hepatocyte death and/or fibrosis, suggesting that the pro-apoptotic role of IRF3 is independent of TLR signaling in fibrosis. Hepatocyte death is required for liver fibrosis with causal involvement of STING and IRF3. Thus, our results identify that IRF3, by its association with STING in the presence of ER stress, couples hepatocyte apoptosis with liver fibrosis and indicate that innate immune signaling regulates outcomes of liver fibrosis via modulation of hepatocyte death in the liver.
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http://dx.doi.org/10.1074/jbc.M116.736991DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5207187PMC
December 2016

Group B Streptococcus Degrades Cyclic-di-AMP to Modulate STING-Dependent Type I Interferon Production.

Cell Host Microbe 2016 Jul;20(1):49-59

Institut Pasteur, Unité de Biologie des Bactéries Pathogènes à Gram-Positif, 75724 Paris, France; Centre National de la Recherche Scientifique (CNRS) ERL 3526, 75724 Paris, France.

Induction of type I interferon (IFN) in response to microbial pathogens depends on a conserved cGAS-STING signaling pathway. The presence of DNA in the cytoplasm activates cGAS, while STING is activated by cyclic dinucleotides (cdNs) produced by cGAS or from bacterial origins. Here, we show that Group B Streptococcus (GBS) induces IFN-β production almost exclusively through cGAS-STING-dependent recognition of bacterial DNA. However, we find that GBS expresses an ectonucleotidase, CdnP, which hydrolyzes extracellular bacterial cyclic-di-AMP. Inactivation of CdnP leads to c-di-AMP accumulation outside the bacteria and increased IFN-β production. Higher IFN-β levels in vivo increase GBS killing by the host. The IFN-β overproduction observed in the absence of CdnP is due to the cumulative effect of DNA sensing by cGAS and STING-dependent sensing of c-di-AMP. These findings describe the importance of a bacterial c-di-AMP ectonucleotidase and suggest a direct bacterial mechanism that dampens activation of the cGAS-STING axis.
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http://dx.doi.org/10.1016/j.chom.2016.06.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5382021PMC
July 2016

Type I Interferon Induction by Neisseria gonorrhoeae: Dual Requirement of Cyclic GMP-AMP Synthase and Toll-like Receptor 4.

Cell Rep 2016 06 2;15(11):2438-48. Epub 2016 Jun 2.

Division of Infectious Diseases, University of Massachusetts Medical School, Worcester, MA 01605, USA; Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA; Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, MG 30190-002, Brazil. Electronic address:

The innate immune system is the first line of defense against Neisseria gonorrhoeae (GC). Exposure of cells to GC lipooligosaccharides induces a strong immune response, leading to type I interferon (IFN) production via TLR4/MD-2. In addition to living freely in the extracellular space, GC can invade the cytoplasm to evade detection and elimination. Double-stranded DNA introduced into the cytosol binds and activates the enzyme cyclic-GMP-AMP synthase (cGAS), which produces 2'3'-cGAMP and triggers STING/TBK-1/IRF3 activation, resulting in type I IFN expression. Here, we reveal a cytosolic response to GC DNA that also contributes to type I IFN induction. We demonstrate that complete IFN-β induction by live GC depends on both cGAS and TLR4. Type I IFN is detrimental to the host, and dysregulation of iron homeostasis genes may explain lower bacteria survival in cGAS(-/-) and TLR4(-/-) cells. Collectively, these observations reveal cooperation between TLRs and cGAS in immunity to GC infection.
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http://dx.doi.org/10.1016/j.celrep.2016.05.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5401638PMC
June 2016

Cutting Edge: DNA in the Lung Microenvironment during Influenza Virus Infection Tempers Inflammation by Engaging the DNA Sensor AIM2.

J Immunol 2016 Jan 20;196(1):29-33. Epub 2015 Nov 20.

Program in Innate Immunity, Division of Infectious Diseases, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605; Centre for Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, 7491 Trondheim, Norway

Innate sensing of nucleic acids lies at the heart of antiviral immunity. During viral infection, dying cells may also release nucleic acids into the tissue microenvironment. It is unknown what effect such host signals have on the quality or duration of the immune response to viruses. In this study, we uncovered an immune-regulatory pathway that tempers the intensity of the host response to influenza A virus (IAV) infection. We found that host-derived DNA accumulates in the lung microenvironment during IAV infection. Ablation of DNA in the lung resulted in increased mortality, increased cellular recruitment, and increased inflammation following IAV challenge. The released DNA, in turn, was sensed by the DNA receptor absent in melanoma 2. Aim2(-/-) mice showed similarly exaggerated immune responses to IAV. Taken together, our results identify a novel mechanism of cross-talk between pathogen- and damage-associated molecular pattern-sensing pathways, wherein sensing of host-derived DNA limits immune-mediated damage to infected tissues.
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http://dx.doi.org/10.4049/jimmunol.1501048DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4793160PMC
January 2016

Virulence of Group A Streptococci Is Enhanced by Human Complement Inhibitors.

PLoS Pathog 2015 Jul 22;11(7):e1005043. Epub 2015 Jul 22.

Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, Malmö, Sweden.

Streptococcus pyogenes, also known as Group A Streptococcus (GAS), is an important human bacterial pathogen that can cause invasive infections. Once it colonizes its exclusively human host, GAS needs to surmount numerous innate immune defense mechanisms, including opsonization by complement and consequent phagocytosis. Several strains of GAS bind to human-specific complement inhibitors, C4b-binding protein (C4BP) and/or Factor H (FH), to curtail complement C3 (a critical opsonin) deposition. This results in diminished activation of phagocytes and clearance of GAS that may lead to the host being unable to limit the infection. Herein we describe the course of GAS infection in three human complement inhibitor transgenic (tg) mouse models that examined each inhibitor (human C4BP or FH) alone, or the two inhibitors together (C4BPxFH or 'double' tg). GAS infection with strains that bound C4BP and FH resulted in enhanced mortality in each of the three transgenic mouse models compared to infection in wild type mice. In addition, GAS manifested increased virulence in C4BPxFH mice: higher organism burdens and greater elevations of pro-inflammatory cytokines and they died earlier than single transgenic or wt controls. The effects of hu-C4BP and hu-FH were specific for GAS strains that bound these inhibitors because strains that did not bind the inhibitors showed reduced virulence in the 'double' tg mice compared to strains that did bind; mortality was also similar in wild-type and C4BPxFH mice infected by non-binding GAS. Our findings emphasize the importance of binding of complement inhibitors to GAS that results in impaired opsonization and phagocytic killing, which translates to enhanced virulence in a humanized whole animal model. This novel hu-C4BPxFH tg model may prove invaluable in studies of GAS pathogenesis and for developing vaccines and therapeutics that rely on human complement activation for efficacy.
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http://dx.doi.org/10.1371/journal.ppat.1005043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4511809PMC
July 2015

Inhibition of sterile danger signals, uric acid and ATP, prevents inflammasome activation and protects from alcoholic steatohepatitis in mice.

J Hepatol 2015 Nov 20;63(5):1147-55. Epub 2015 Jun 20.

University of Massachusetts Medical School, Worcester, MA, USA. Electronic address:

Background & Aims: The inflammasome is a well-characterized inducer of inflammation in alcoholic steatohepatitis (ASH). Inflammasome activation requires two signals for mature interleukin (IL)-1β production. Here we asked whether metabolic danger signals trigger inflammasome activation in ASH.

Methods: Wild-type mice, ATP receptor 2x7 (P2rx7)-KO mice, or mice overexpressing uricase were fed Lieber-DeCarli ethanol or control diet. We also implemented a pharmacological approach in which mice were treated with probenecid or allopurinol.

Results: The sterile danger signals, ATP and uric acid, were increased in the serum and liver of alcohol-fed mice. Depletion of uric acid or ATP, or lack of ATP signaling attenuated ASH and prevented inflammasome activation and its major downstream cytokine, IL-1β. Pharmacological depletion of uric acid with allopurinol provided significant protection from alcohol-induced inflammatory response, steatosis and liver damage, and additional protection was achieved in mice treated with probenecid, which depletes uric acid and blocks ATP-induced P2rx7 signaling. We found that alcohol-damaged hepatocytes released uric acid and ATP in vivo and in vitro and that these sterile danger signals activated the inflammasome in LPS-exposed liver mononuclear cells.

Conclusions: Our data indicate that the second signal in inflammasome activation and IL-1β production in ASH results from the endogenous danger signals, uric acid and ATP. Inhibition of signaling triggered by uric acid and ATP may have therapeutic implications in ASH.
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http://dx.doi.org/10.1016/j.jhep.2015.06.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4615393PMC
November 2015

Metabolic danger signals, uric acid and ATP, mediate inflammatory cross-talk between hepatocytes and immune cells in alcoholic liver disease.

J Leukoc Biol 2015 Aug 1;98(2):249-56. Epub 2015 May 1.

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA

Inflammation defines the progression of ALD from reversible to advanced stages. Translocation of bacterial LPS to the liver from the gut is necessary for alcohol-induced liver inflammation. However, it is not known whether endogenous, metabolic danger signals are required for inflammation in ALD. Uric acid and ATP, 2 major proinflammatory danger signals, were evaluated in the serum of human volunteers exposed to a single dose of ethanol or in supernatants of primary human hepatocytes exposed to ethanol. In vitro studies were used to evaluate the role of uric acid and ATP in inflammatory cross-talk between hepatocytes and immune cells. The significance of signaling downstream of uric acid and ATP in the liver was evaluated in NLRP3-deficient mice fed a Lieber-DeCarli ethanol diet. Exposure of healthy human volunteers to a single dose of ethanol resulted in increased serum levels of uric acid and ATP. In vitro, we identified hepatocytes as a significant source of these endogenous inflammatory signals. Uric acid and ATP mediated a paracrine inflammatory cross-talk between damaged hepatocytes and immune cells and significantly increased the expression of LPS-inducible cytokines, IL-1β and TNF-α, by immune cells. Deficiency of NLRP3, a ligand-sensing component of the inflammasome recognizing uric acid and ATP, prevented the development of alcohol-induced liver inflammation in mice and significantly ameliorated liver damage and steatosis. Endogenous metabolic danger signals, uric acid, and ATP are involved in inflammatory cross-talk between hepatocytes and immune cells and play a crucial role in alcohol-induced liver inflammation.
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http://dx.doi.org/10.1189/jlb.3AB1214-590RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4501673PMC
August 2015

Positive Selection Drives Preferred Segment Combinations during Influenza Virus Reassortment.

Mol Biol Evol 2015 Jun 23;32(6):1519-32. Epub 2015 Feb 23.

Department of Medicine, University of Massachusetts Medical School, Worcester.

Influenza A virus (IAV) has a segmented genome that allows for the exchange of genome segments between different strains. This reassortment accelerates evolution by breaking linkage, helping IAV cross species barriers to potentially create highly virulent strains. Challenges associated with monitoring the process of reassortment in molecular detail have limited our understanding of its evolutionary implications. We applied a novel deep sequencing approach with quantitative analysis to assess the in vitro temporal evolution of genomic reassortment in IAV. The combination of H1N1 and H3N2 strains reproducibly generated a new H1N2 strain with the hemagglutinin and nucleoprotein segments originating from H1N1 and the remaining six segments from H3N2. By deep sequencing the entire viral genome, we monitored the evolution of reassortment, quantifying the relative abundance of all IAV genome segments from the two parent strains over time and measuring the selection coefficients of the reassorting segments. Additionally, we observed several mutations coemerging with reassortment that were not found during passaging of pure parental IAV strains. Our results demonstrate how reassortment of the segmented genome can accelerate viral evolution in IAV, potentially enabled by the emergence of a small number of individual mutations.
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http://dx.doi.org/10.1093/molbev/msv044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4462674PMC
June 2015

Heparin octasaccharide decoy liposomes inhibit replication of multiple viruses.

Antiviral Res 2015 Apr 28;116:34-44. Epub 2015 Jan 28.

Department of Medicine, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, United States.

Heparan sulfate (HS) is a ubiquitous glycosaminoglycan that serves as a cellular attachment site for a number of significant human pathogens, including respiratory syncytial virus (RSV), human parainfluenza virus 3 (hPIV3), and herpes simplex virus (HSV). Decoy receptors can target pathogens by binding to the receptor pocket on viral attachment proteins, acting as 'molecular sinks' and preventing the pathogen from binding to susceptible host cells. Decoy receptors functionalized with HS could bind to pathogens and prevent infection, so we generated decoy liposomes displaying HS-octasaccharide (HS-octa). These decoy liposomes significantly inhibited RSV, hPIV3, and HSV infectivity in vitro to a greater degree than the original HS-octa building block. The degree of inhibition correlated with the density of HS-octa displayed on the liposome surface. Decoy liposomes with HS-octa inhibited infection of viruses to a greater extent than either full-length heparin or HS-octa alone. Decoy liposomes were effective when added prior to infection or following the initial infection of cells in vitro. By targeting the well-conserved receptor-binding sites of HS-binding viruses, decoy liposomes functionalized with HS-octa are a promising therapeutic antiviral agent and illustrate the utility of the liposome delivery platform.
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http://dx.doi.org/10.1016/j.antiviral.2015.01.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4988063PMC
April 2015

Interferon γ-inducible protein (IFI) 16 transcriptionally regulates type i interferons and other interferon-stimulated genes and controls the interferon response to both DNA and RNA viruses.

J Biol Chem 2014 Aug 7;289(34):23568-81. Epub 2014 Jul 7.

From the Division of Infectious Disease and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605,

The interferon γ-inducible protein 16 (IFI16) has recently been linked to the detection of nuclear and cytosolic DNA during infection with herpes simplex virus-1 and HIV. IFI16 binds dsDNA via HIN200 domains and activates stimulator of interferon genes (STING), leading to TANK (TRAF family member-associated NF-κB activator)-binding kinase-1 (TBK1)-dependent phosphorylation of interferon regulatory factor (IRF) 3 and transcription of type I interferons (IFNs) and related genes. To better understand the role of IFI16 in coordinating type I IFN gene regulation, we generated cell lines with stable knockdown of IFI16 and examined responses to DNA and RNA viruses as well as cyclic dinucleotides. As expected, stable knockdown of IFI16 led to a severely attenuated type I IFN response to DNA ligands and viruses. In contrast, expression of the NF-κB-regulated cytokines IL-6 and IL-1β was unaffected in IFI16 knockdown cells, suggesting that the role of IFI16 in sensing these triggers was unique to the type I IFN pathway. Surprisingly, we also found that knockdown of IFI16 led to a severe attenuation of IFN-α and the IFN-stimulated gene retinoic acid-inducible gene I (RIG-I) in response to cyclic GMP-AMP, a second messenger produced by cyclic GMP-AMP synthase (cGAS) as well as RNA ligands and viruses. Analysis of IFI16 knockdown cells revealed compromised occupancy of RNA polymerase II on the IFN-α promoter in these cells, suggesting that transcription of IFN-stimulated genes is dependent on IFI16. These results indicate a broader role for IFI16 in the regulation of the type I IFN response to RNA and DNA viruses in antiviral immunity.
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http://dx.doi.org/10.1074/jbc.M114.554147DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4156042PMC
August 2014

3-Hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor (statin)-induced 28-kDa interleukin-1β interferes with mature IL-1β signaling.

J Biol Chem 2014 Jun 30;289(23):16214-22. Epub 2014 Apr 30.

From the Division of Infectious Disease and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605 and

Multiple clinical trials have shown that the 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors known as statins have anti-inflammatory effects. However, the underlying molecular mechanism remains unclear. The proinflammatory cytokine interleukin-1β (IL-1β) is synthesized as a non-active precursor. The 31-kDa pro-IL-1β is processed into the 17-kDa active form by caspase-1-activating inflammasomes. Here, we report a novel signaling pathway induced by statins, which leads to processing of pro-IL-1β into an intermediate 28-kDa form. This statin-induced IL-1β processing is independent of caspase-1- activating inflammasomes. The 28-kDa form of IL-1β cannot activate interleukin-1 receptor-1 (IL1R1) to signal inflammatory responses. Instead, it interferes with mature IL-1β signaling through IL-1R1 and therefore may dampen inflammatory responses initiated by mature IL-1β. These results may provide new clues to explain the anti-inflammatory effects of statins.
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http://dx.doi.org/10.1074/jbc.M114.571505DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4047391PMC
June 2014

Platelet-TLR7 mediates host survival and platelet count during viral infection in the absence of platelet-dependent thrombosis.

Blood 2014 Jul 22;124(5):791-802. Epub 2014 Apr 22.

Division of Cardiovascular Medicine, Department of Medicine, University of Massachusetts Medical School, Worcester, MA;

Viral infections have been associated with reduced platelet counts, the biological significance of which has remained elusive. Here, we show that infection with encephalomyocarditis virus (EMCV) rapidly reduces platelet count, and this response is attributed to platelet Toll-like receptor 7 (TLR7). Platelet-TLR7 stimulation mediates formation of large platelet-neutrophil aggregates, both in mouse and human blood. Intriguingly, this process results in internalization of platelet CD41-fragments by neutrophils, as assessed biochemically and visualized by microscopy, with no influence on platelet prothrombotic properties. The mechanism includes TLR7-mediated platelet granule release, translocation of P-selectin to the cell surface, and a consequent increase in platelet-neutrophil adhesion. Viral infection of platelet-depleted mice also led to increased mortality. Transfusion of wild-type, TLR7-expressing platelets into TLR7-deficient mice caused a drop in platelet count and increased survival post EMCV infection. Thus, this study identifies a new link between platelets and their response to single-stranded RNA viruses that involves activation of TLR7. Finally, platelet-TLR7 stimulation is independent of thrombosis and has implications to the host immune response and survival.
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http://dx.doi.org/10.1182/blood-2013-11-536003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4118487PMC
July 2014

Both bone marrow-derived and non-bone marrow-derived cells contribute to AIM2 and NLRP3 inflammasome activation in a MyD88-dependent manner in dietary steatohepatitis.

Liver Int 2014 Oct 17;34(9):1402-13. Epub 2014 Apr 17.

Department of Medicine, University of Massachusetts Medical School, Worcester, MA, USA.

Background & Aims: Inflammation promotes the progression of non-alcoholic steatohepatitis (NASH). Toll-like receptor 4 (TLR4) and TLR9 activation through myeloid differentiation primary response gene 88 (MyD88) and production of mature interleukin-1β (IL-1β) via inflammasome activation contribute to steatohepatitis. Here, we investigated the inter-relationship between TLR signalling and inflammasome activation in dietary steatohepatitis.

Methods: Wild type (WT), TLR4- and MyD88-deficient (KO) mice received methionine-choline-deficient (MCD) or -supplemented (MCS) diets for 5 weeks and a subset was challenged with TLR9 ligand CpG-DNA.

Results: TLR4, TLR9, AIM2 (absent in melanoma 2) and NLRP3 (NLR family pyrin domain containing 3) inflammasome mRNA, and mature IL-1β protein levels were increased in MCD diet-induced steatohepatitis compared to MCS controls. TLR9 stimulation resulted in greater up-regulation of the DNA-sensing AIM2 expression and IL-1β production in livers of MCD compared to MCS diet-fed mice. High mobility group box 1 (HMGB1), a TLR9-activating danger molecule and phospho-HMGB1 protein levels were also increased in livers of MCD diet-fed mice. MyD88- but not TLR4-deficiency prevented up-regulation of AIM2, NLRP3 mRNA and IL-1β protein production in dietary steatohepatitis. Selective MyD88 deficiency either in bone marrow (BM)-derived or non-BM-derived cells attenuated hepatic up-regulation of inflammasome mRNA, caspase-1 activation and IL-1β protein production, but only BM-derived cell-specific MyD88-deficiency attenuated liver injury.

Conclusions: Our data demonstrate that both bone marrow-derived and non-BM-derived cells contribute to inflammasome activation in a MyD88-dependent manner in dietary steatohepatitis. We show that AIM2 inflammasome expression and activation are further augmented by TLR9 ligands in dietary steatohepatitis.
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http://dx.doi.org/10.1111/liv.12537DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169310PMC
October 2014

Dicer's role as an antiviral: still an enigma.

Curr Opin Immunol 2014 Feb 22;26:49-55. Epub 2013 Nov 22.

Department of Medicine, Division of Infectious Diseases and Immunology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA 01605, USA. Electronic address:

Dicer is a multifunctional protein that is essential across species for the generation of microRNAs, a function that is highly conserved across the plant and animal kingdoms. Intriguingly, Dicer exhibits antiviral functions in lower organisms including Drosophila melanogaster and Caenorhabditis elegans. Antiviral activity occurs via small interfering RNA production following cytoplasmic sensing of viral dsRNA. Notably, such antiviral activity has not yet been clearly demonstrated in higher organisms such as mammals. Here, we review the evidence for Dicer as an innate antiviral across species.
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http://dx.doi.org/10.1016/j.coi.2013.10.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932008PMC
February 2014

The transcriptional repressor BLIMP1 curbs host defenses by suppressing expression of the chemokine CCL8.

J Immunol 2014 Mar 29;192(5):2291-304. Epub 2014 Jan 29.

Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605;

The transcriptional repressor B lymphocyte-induced maturation protein 1 (BLIMP1) is a master regulator of B and T cell differentiation. To examine the role of BLIMP1 in innate immunity, we used a conditional knockout (CKO) of Blimp1 in myeloid cells and found that Blimp1 CKO mice were protected from lethal infection induced by Listeria monocytogenes. Transcriptome analysis of Blimp1 CKO macrophages identified the murine chemokine (C-C motif) ligand 8, CCL8, as a direct target of Blimp1-mediated transcriptional repression in these cells. BLIMP1-deficient macrophages expressed elevated levels of Ccl8, and consequently Blimp1 CKO mice had higher levels of circulating CCL8, resulting in increased neutrophils in the peripheral blood, promoting a more aggressive antibacterial response. Mice lacking the Ccl8 gene were more susceptible to L. monocytogenes infection than were wild-type mice. Although CCL8 failed to recruit neutrophils directly, it was chemotactic for γ/δ T cells, and CCL8-responsive γ/δ T cells were enriched for IL-17F. Finally, CCL8-mediated enhanced clearance of L. monocytogenes was dependent on γ/δ T cells. Collectively, these data reveal an important role for BLIMP1 in modulating host defenses by suppressing expression of the chemokine CCL8.
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http://dx.doi.org/10.4049/jimmunol.1301799DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943885PMC
March 2014

Evolution of the influenza A virus genome during development of oseltamivir resistance in vitro.

J Virol 2014 Jan 23;88(1):272-81. Epub 2013 Oct 23.

Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA.

Influenza A virus (IAV) is a major cause of morbidity and mortality throughout the world. Current antiviral therapies include oseltamivir, a neuraminidase inhibitor that prevents the release of nascent viral particles from infected cells. However, the IAV genome can evolve rapidly, and oseltamivir resistance mutations have been detected in numerous clinical samples. Using an in vitro evolution platform and whole-genome population sequencing, we investigated the population genomics of IAV during the development of oseltamivir resistance. Strain A/Brisbane/59/2007 (H1N1) was grown in Madin-Darby canine kidney cells with or without escalating concentrations of oseltamivir over serial passages. Following drug treatment, the H274Y resistance mutation fixed reproducibly within the population. The presence of the H274Y mutation in the viral population, at either a low or a high frequency, led to measurable changes in the neuraminidase inhibition assay. Surprisingly, fixation of the resistance mutation was not accompanied by alterations of viral population diversity or differentiation, and oseltamivir did not alter the selective environment. While the neighboring K248E mutation was also a target of positive selection prior to H274Y fixation, H274Y was the primary beneficial mutation in the population. In addition, once evolved, the H274Y mutation persisted after the withdrawal of the drug, even when not fixed in viral populations. We conclude that only selection of H274Y is required for oseltamivir resistance and that H274Y is not deleterious in the absence of the drug. These collective results could offer an explanation for the recent reproducible rise in oseltamivir resistance in seasonal H1N1 IAV strains in humans.
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http://dx.doi.org/10.1128/JVI.01067-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3911755PMC
January 2014

STING-IRF3 pathway links endoplasmic reticulum stress with hepatocyte apoptosis in early alcoholic liver disease.

Proc Natl Acad Sci U S A 2013 Oct 19;110(41):16544-9. Epub 2013 Sep 19.

Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605.

Emerging evidence suggests that innate immunity drives alcoholic liver disease (ALD) and that the interferon regulatory factor 3 (IRF3),a transcription factor regulating innate immune responses, is indispensable for the development of ALD. Here we report that IRF3 mediates ALD via linking endoplasmic reticulum (ER) stress with apoptotic signaling in hepatocytes. We found that ethanol induced ER stress and triggered the association of IRF3 with the ER adaptor, stimulator of interferon genes (STING), as well as subsequent phosphorylation of IRF3. Activated IRF3 associated with the proapoptotic molecule Bax [B-cell lymphoma 2 (Bcl2)-associated X protein] and contributed to hepatocyte apoptosis. Deficiency of STING prevented IRF3 phosphorylation by ethanol or ER stress, and absence of IRF3 prevented hepatocyte apoptosis. The pathogenic role of IRF3 in ALD was independent of inflammation or Type-I interferons. Thus, STING and IRF3 are key determinants of ALD, linking ER stress signaling with the mitochondrial pathway of hepatocyte apoptosis.
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http://dx.doi.org/10.1073/pnas.1308331110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3799324PMC
October 2013

Chronic alcohol-induced microRNA-155 contributes to neuroinflammation in a TLR4-dependent manner in mice.

PLoS One 2013 9;8(8):e70945. Epub 2013 Aug 9.

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA.

Introduction: Alcohol-induced neuroinflammation is mediated by pro-inflammatory cytokines and chemokines including tumor necrosis factor-α (TNFα), monocyte chemotactic protein-1 (MCP1) and interleukin-1-beta (IL-1β). Toll-like receptor-4 (TLR4) pathway induced nuclear factor-κB (NF-κB) activation is involved in the pathogenesis of alcohol-induced neuroinflammation. Inflammation is a highly regulated process. Recent studies suggest that microRNAs (miRNAs) play crucial role in fine tuning gene expression and miR-155 is a major regulator of inflammation in immune cells after TLR stimulation.

Aim: To evaluate the role of miR-155 in the pathogenesis of alcohol-induced neuroinflammation.

Methods: Wild type (WT), miR-155- and TLR4-knockout (KO) mice received 5% ethanol-containing or isocaloric control diet for 5 weeks. Microglia markers were measured by q-RTPCR; inflammasome activation was measured by enzyme activity; TNFα, MCP1, IL-1β mRNA and protein were measured by q-RTPCR and ELISA; phospho-p65 protein and NF-κB were measured by Western-blotting and EMSA; miRNAs were measured by q-PCR in the cerebellum. MiR-155 was measured in immortalized and primary mouse microglia after lipopolysaccharide and ethanol stimulation.

Results: Chronic ethanol feeding up-regulated miR-155 and miR-132 expression in mouse cerebellum. Deficiency in miR-155 protected mice from alcohol-induced increase in inflammatory cytokines; TNFα, MCP1 protein and TNFα, MCP1, pro-IL-1β and pro-caspase-1 mRNA levels were reduced in miR-155 KO alcohol-fed mice. NF-κB was activated in WT but not in miR-155 KO alcohol-fed mice. However increases in cerebellar caspase-1 activity and IL-1β levels were similar in alcohol-fed miR-155-KO and WT mice. Alcohol-fed TLR4-KO mice were protected from the induction of miR-155. NF-κB activation measured by phosphorylation of p65 and neuroinflammation were reduced in alcohol-fed TLR4-KO compared to control mice. TLR4 stimulation with lipopolysaccharide in primary or immortalized mouse microglia resulted in increased miR-155.

Conclusion: Chronic alcohol induces miR-155 in the cerebellum in a TLR4-dependent manner. Alcohol-induced miR-155 regulates TNFα and MCP1 expression but not caspase-dependent IL-1β increase in neuroinflammation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0070945PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3739772PMC
March 2014

Alcohol-induced IL-1β in the brain is mediated by NLRP3/ASC inflammasome activation that amplifies neuroinflammation.

J Leukoc Biol 2013 Jul 26;94(1):171-82. Epub 2013 Apr 26.

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA.

Alcohol-induced neuroinflammation is mediated by proinflammatory cytokines, including IL-1β. IL-1β production requires caspase-1 activation by inflammasomes-multiprotein complexes that are assembled in response to danger signals. We hypothesized that alcohol-induced inflammasome activation contributes to increased IL-1β in the brain. WT and TLR4-, NLRP3-, and ASC-deficient (KO) mice received an ethanol-containing or isocaloric control diet for 5 weeks, and some received the rIL-1ra, anakinra, or saline treatment. Inflammasome activation, proinflammatory cytokines, endotoxin, and HMGB1 were measured in the cerebellum. Expression of inflammasome components (NLRP1, NLRP3, ASC) and proinflammatory cytokines (TNF-α, MCP-1) was increased in brains of alcohol-fed compared with control mice. Increased caspase-1 activity and IL-1β protein in ethanol-fed mice indicated inflammasome activation. TLR4 deficiency protected from TNF-α, MCP-1, and attenuated alcohol-induced IL-1β increases. The TLR4 ligand, LPS, was not increased in the cerebellum. However, we found up-regulation of acetylated and phosphorylated HMGB1 and increased expression of the HMGB1 receptors (TLR2, TLR4, TLR9, RAGE) in alcohol-fed mice. NLRP3- or ASC-deficient mice were protected from caspase-1 activation and alcohol-induced IL-1β increase in the brain. Furthermore, in vivo treatment with rIL-1ra prevented alcohol-induced inflammasome activation and IL-1β, TNF-α, and acetylated HMGB1 increases in the cerebellum. Conversely, intracranial IL-1β administration induced TNF-α and MCP-1 in the cerebellum. In conclusion, alcohol up-regulates and activates the NLRP3/ASC inflammasome, leading to caspase-1 activation and IL-1β increase in the cerebellum. IL-1β amplifies neuroinflammation, and disruption of IL-1/IL-1R signaling prevents alcohol-induced inflammasome activation and neuroinflammation. Increased levels of acetylated and phosphorylated HMGB1 may contribute to alcoholic neuroinflammation.
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http://dx.doi.org/10.1189/jlb.1212659DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3685015PMC
July 2013

Tuning innate immune activation by surface texturing of polymer microparticles: the role of shape in inflammasome activation.

J Immunol 2013 Apr 20;190(7):3525-32. Epub 2013 Feb 20.

Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA.

Polymeric microparticles have been widely investigated as platforms for delivery of drugs, vaccines, and imaging contrast agents and are increasingly used in a variety of clinical applications. Microparticles activate the inflammasome complex and induce the processing and secretion of IL-1β, a key innate immune cytokine. Recent work suggests that although receptors are clearly important for particle phagocytosis, other physical characteristics, especially shape, play an important role in the way microparticles activate cells. We examined the role of particle surface texturing not only on uptake efficiency but also on the subsequent immune cell activation of the inflammasome. Using a method based on emulsion processing of amphiphilic block copolymers, we prepared microparticles with similar overall sizes and surface chemistries but having either smooth or highly microtextured surfaces. In vivo, textured (budding) particles induced more rapid neutrophil recruitment to the injection site. In vitro, budding particles were more readily phagocytosed than smooth particles and induced more lipid raft recruitment to the phagosome. Remarkably, budding particles also induced stronger IL-1β secretion than smooth particles through activation of the NLRP3 inflammasome. These findings demonstrate a pronounced role of particle surface topography in immune cell activation, suggesting that shape is a major determinant of inflammasome activation.
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http://dx.doi.org/10.4049/jimmunol.1200492DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3646559PMC
April 2013

Sialylneolacto-N-tetraose c (LSTc)-bearing liposomal decoys capture influenza A virus.

J Biol Chem 2013 Mar 28;288(12):8061-8073. Epub 2013 Jan 28.

Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts 01605. Electronic address:

Influenza is a severe disease in humans and animals with few effective therapies available. All strains of influenza virus are prone to developing drug resistance due to the high mutation rate in the viral genome. A therapeutic agent that targets a highly conserved region of the virus could bypass resistance and also be effective against multiple strains of influenza. Influenza uses many individually weak ligand binding interactions for a high avidity multivalent attachment to sialic acid-bearing cells. Polymerized sialic acid analogs can form multivalent interactions with influenza but are not ideal therapeutics due to solubility and toxicity issues. We used liposomes as a novel means for delivery of the glycan sialylneolacto-N-tetraose c (LSTc). LSTc-bearing decoy liposomes form multivalent, polymer-like interactions with influenza virus. Decoy liposomes competitively bind influenza virus in hemagglutination inhibition assays and inhibit infection of target cells in a dose-dependent manner. Inhibition is specific for influenza virus, as inhibition of Sendai virus and respiratory syncytial virus is not observed. In contrast, monovalent LSTc does not bind influenza virus or inhibit infectivity. LSTc decoy liposomes prevent the spread of influenza virus during multiple rounds of replication in vitro and extend survival of mice challenged with a lethal dose of virus. LSTc decoy liposomes co-localize with fluorescently tagged influenza virus, whereas control liposomes do not. Considering the conservation of the hemagglutinin binding pocket and the ability of decoy liposomes to form high avidity interactions with influenza hemagglutinin, our decoy liposomes have potential as a new therapeutic agent against emerging influenza strains.
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http://dx.doi.org/10.1074/jbc.M112.437202DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3605625PMC
March 2013