Phylogenetic conservatism and antiquity of a tropical specialization: Army-ant-following in the typical antbirds (Thamnophilidae)

One of the most novel foraging strategies in Neotropical birds is army-ant-following, in which birds prey upon arthropods and small vertebrates flushed from the forest floor by swarm raids of the army-ant Eciton burchellii. This specialization is most developed in the typical antbirds (Thamnophilidae) which are divisible into three specialization categories: (1) those that forage at swarms opportunistically as army-ants move through their territories (occasional followers), (2) those that follow swarms beyond their territories but also forage independently of swarms (regular followers), and (3) those that appear incapable of foraging independently of swarms (obligate followers). Although army-ant-following is one of the great spectacles of tropical forests, basic questions about its evolution remain unaddressed. Using a strongly resolved molecular phylogeny of the typical antbirds, we found that army-ant-following is phylogenetically conserved, with regular following having evolved only three times, and that the most likely evolutionary progression was from least (occasional) to more (regular) to most (obligate) specialized, with no reversals from the obligate state. Despite the dependence of the specialists on a single ant species, molecular dating indicates that army-ant-following has persisted in antbirds since the late Miocene. These results provide the first characterization of army-ant-following as an ancient and phylogenetically conserved specialization. © 2007 Elsevier Inc. All rights reserved

IL-1β Production through the NLRP3 Inflammasome by Hepatic Macrophages Links Hepatitis C Virus Infection with Liver Inflammation and Disease

Chronic hepatitis C virus (HCV) infection is a leading cause of liver disease. Liver inflammation underlies infection-induced fibrosis, cirrhosis and liver cancer but the processes that promote hepatic inflammation by HCV are not defined. We provide a systems biology analysis with multiple lines of evidence to indicate that interleukin-1β (IL-1β) production by intrahepatic macrophages confers liver inflammation through HCV-induced inflammasome signaling. Chronic hepatitis C patients exhibited elevated levels of serum IL-1β compared to healthy controls. Immunohistochemical analysis of healthy control and chronic hepatitis C liver sections revealed that Kupffer cells, resident hepatic macrophages, are the primary cellular source of hepatic IL-1β during HCV infection. Accordingly, we found that both blood monocyte-derived primary human macrophages, and Kupffer cells recovered from normal donor liver, produce IL-1β after HCV exposure. Using the THP-1 macrophage cell-culture model, we found that HCV drives a rapid but transient caspase-1 activation to stimulate IL-1β secretion. HCV can enter macrophages through non-CD81 mediated phagocytic uptake that is independent of productive infection. Viral RNA triggers MyD88-mediated TLR7 signaling to induce IL-1β mRNA expression. HCV uptake concomitantly induces a potassium efflux that activates the NLRP3 inflammasome for IL-1β processing and secretion. RNA sequencing analysis comparing THP1 cells and chronic hepatitis C patient liver demonstrates that viral engagement of the NLRP3 inflammasome stimulates IL-1β production to drive proinflammatory cytokine, chemokine, and immune-regulatory gene expression networks linked with HCV disease severity. These studies identify intrahepatic IL-1β production as a central feature of liver inflammation during HCV infection. Thus, strategies to suppress NLRP3 or IL-1β activity could offer therapeutic actions to reduce hepatic inflammation and mitigate disease

Innate Immune Tolerance and the Role of Kupffer Cells in Differential Responses to Interferon Therapy Among Patients With HCV Genotype 1 Infection

In patients with hepatitis C virus (HCV) infection, interferon alfa (IFN-α) alters expression of IFN-stimulated genes (ISGs), but little is understood about factors that determine outcomes of therapy. We used a systems biology approach to evaluate the acute response of patients with chronic hepatitis C to IFN-α therapy

Distinct RIG-I and MDA5 Signaling by RNA Viruses in Innate Immunity▿

Alpha/beta interferon immune defenses are essential for resistance to viruses and can be triggered through the actions of the cytoplasmic helicases retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5). Signaling by each is initiated by the recognition of viral products such as RNA and occurs through downstream interaction with the IPS-1 adaptor protein. We directly compared the innate immune signaling requirements of representative viruses of the Flaviviridae, Orthomyxoviridae, Paramyxoviridae, and Reoviridae for RIG-I, MDA5, and interferon promoter-stimulating factor 1 (IPS-1). In cultured fibroblasts, IPS-1 was essential for innate immune signaling of downstream interferon regulatory factor 3 activation and interferon-stimulated gene expression, but the requirements for RIG-I and MDA5 were variable. Each was individually dispensable for signaling triggered by reovirus and dengue virus, whereas RIG-I was essential for signaling by influenza A virus, influenza B virus, and human respiratory syncytial virus. Functional genomics analyses identified cellular genes triggered during influenza A virus infection whose expression was strictly dependent on RIG-I and which are involved in processes of innate or adaptive immunity, apoptosis, cytokine signaling, and inflammation associated with the host response to contemporary and pandemic strains of influenza virus. These results define IPS-1-dependent signaling as an essential feature of host immunity to RNA virus infection. Our observations further demonstrate differential and redundant roles for RIG-I and MDA5 in pathogen recognition and innate immune signaling that may reflect unique and shared biologic properties of RNA viruses whose differential triggering and control of gene expression may impact pathogenesis and infection

Rapid reversal of innate immune dysregulation in blood of patients and livers of humanized mice with HCV following DAA therapy

<div><p>Chronic hepatitis C virus (HCV) infection results in sustained immune activation in both the periphery and hepatic tissue. HCV infection induces innate immune signaling that is responsible for recognition of dsRNA, leading to activation of transcription factors and production of Type I and III IFNs, as well as pro-inflammatory cytokines and chemokines. Continued activation of host-immune mediated inflammation is thought to contribute to pathologic changes that result in progressive hepatic fibrosis. The current standard treatment for chronic HCV infection is directly-acting antivirals (DAAs), which have provided the unique opportunity to determine whether successful, rapid treatment-induced eradication of viral RNA normalizes the dysregulated antiviral innate immune response in patients chronically infected with HCV.</p><p>Results</p><p>First, in patients receiving two different combinations of DAAs, we found that DAAs induced not only rapid viral clearance, but also a re-setting of antiviral immune responses in the peripheral blood. Specifically, we see a rapid decline in the expression of genes associated with chronic IFN stimulation (IFIT3, USP18, IFIT1) as well as a rapid decline in genes associated with inflammation (IL1β, CXCL10, CXCL11) in the peripheral blood that precedes the complete removal of virus from the blood. Interestingly, this rapid reversal of innate immune activation was not seen in patients who successfully clear chronic HCV infection using IFN-based therapy. Next, using a novel humanized mouse model <i>(Fah</i>^<i>-/-</i><i>RAG2</i>^<i>-/-</i><i>IL2rg</i>^<i>null</i>—FRG), we assessed the changes that occur in the hepatic tissue following DAA treatment. DAA-mediated rapid HCV clearance resulted in blunting of the expression of proinflammatory responses while functionally restoring the RIG-I/MAVS axis in the liver of humanized mice.</p><p>Conclusions</p><p>Collectively, our data demonstrate that the rapid viral clearance following treatment with DAAs results in the rebalancing of innate antiviral response in both the peripheral blood and the liver as well as enhanced antiviral signaling within previously infected hepatocytes.</p></div

DAA therapy induces rapid suppression of some but not all antiviral signaling molecules.

<p>Kinetic analysis of transcriptional levels of CXCL10 (black), CXCL11 (purple), RIG-I (yellow), IRF3 (blue), IFIT1(ISG56) (red), IFITM1 (grey), USP18 (green), IL1β (black circles, dotted line) and plasma viral load (black crosses with black dashed line) from PBMCs in DAA patient cohort 2 (n = 11).</p

Restoration of HCV-suppressed antiviral signaling in the liver of humanized mice treated with DAAs.

<p><b>(A)</b> Serum levels of HCV in mice injected with 1.4 x 10⁶ IU HCV intravenously. <b>(B)</b> HCV viral loads after treatment with Sofosbuvir (2.0mg daily), Daclatasvir (0.3mg daily), Asunaprevir (0.5mg twice daily) or DMSO vehicle control via oral gavage. <b>(C)</b> Protein expression of NS3, MAVS, IFITM1, and IRF3 following 14 days of DMSO treatment or DAA treatment in whole liver tissue via immunofluorescence staining. N = 3 mice per group. ****P<0.0001, NS = Not significant.</p

Predicted changes in activation status of upstream regulators (IPA) in the peripheral blood of patients receiving DAA therapy.

<p>Predicted changes in activation status of upstream regulators (IPA) in the peripheral blood of patients receiving DAA therapy.</p

Differential transcriptional changes are associated with IFN-free DAA therapy and IFN/Ribavirin therapy.

<p><b>(A)</b> Representation of the shared and different transcriptional changes in DAA therapy (EOT) compared to IFNα/Ribavirin therapy (wk 10) (19). The top 1000 genes statistically significantly changed from pretreatment in both data sets were compared to the expression of the given gene in the other treatment cohort. <b>(B)</b> List of the 32 genes that were statistically changed from post treatment to pretreatment in both data sets. <b>(C)</b> Quantitative RT-PCR comparing fold change from pretreatment at twelve weeks following DAA therapy (Black Bars) and twenty-four weeks following IFNα/Ribavirin therapy (White bars). P value represents comparison between both treatments. P<0.05, ***P<0.001, NS = Not significant. N = 8-11patients per group.</p