A Fluorescent Reporter Mouse for Inflammasome Assembly Demonstrates an Important Role for Cell-Bound and Free ASC Specks during In Vivo Infection.

Inflammasome activation is associated with numerous diseases. However, in vivo detection of the activated inflammasome complex has been limited by a dearth of tools. We have developed transgenic mice that ectopically express the fluorescent adaptor protein, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and characterized the formation of assembled inflammasome complexes ("specks") in primary cells and tissues.

CD200R1 supports HSV-1 viral replication and licenses pro-inflammatory signaling functions of TLR2.

The CD200R1:CD200 axis is traditionally considered to limit tissue inflammation by down-regulating pro-inflammatory signaling in myeloid cells bearing the receptor. We generated CD200R1(-/-) mice and employed them to explore both the role of CD200R1 in regulating macrophage signaling via TLR2 as well as the host response to an in vivo, TLR2-dependent model, herpes simplex virus 1 (HSV-1) infection. CD200R1(-/-) peritoneal macrophages demonstrated a 70-75% decrease in the generation of IL-6 and CCL5 (Rantes) in response to the TLR2 agonist Pam(2)CSK(4) and to HSV-1.

Methods for in vivo and in vitro analysis of innate immune responses to Helicobacter pylori infection.

It is estimated that half of the world's population is infected by Helicobacter pylori (H. pylori) (Polk and Peek, Nat Rev Cancer 10:403-414, 2010; Peek et al., Physiol Rev 90:831-858, 2010).

Role of interferon regulatory factor 7 in T cell responses during acute lymphocytic choriomeningitis virus infection.

Type I interferons (IFNs), predominantly IFN-α and -β, play critical roles in both innate and adaptive immune responses against viral infections. Interferon regulatory factor 7 (IRF7), a key innate immune molecule in the type I IFN signaling pathway, is essential for the type I IFN response to many viruses, including lymphocytic choriomeningitis virus (LCMV). Here, we show that although IRF7 knockout (KO) mice failed to control the replication of LCMV in the early stages of infection, they were capable of clearing LCMV infection.

CD14 deficiency impacts glucose homeostasis in mice through altered adrenal tone.

The toll-like receptors comprise one of the most conserved components of the innate immune system, signaling the presence of molecules of microbial origin. It has been proposed that signaling through TLR4, which requires CD14 to recognize bacterial lipopolysaccharide (LPS), may generate low-grade inflammation and thereby affect insulin sensitivity and glucose metabolism. To examine the long-term influence of partial innate immune signaling disruption on glucose homeostasis, we analyzed knockout mice deficient in CD14 backcrossed into the diabetes-prone C57BL6 background at 6 or 12 months of age.

Role of specific innate immune responses in herpes simplex virus infection of the central nervous system.

Herpes simplex virus 1 (HSV-1) causes a spectrum of disease, including herpes labialis, herpes keratitis, and herpes encephalitis, which can be lethal. Viral recognition by pattern recognition receptors plays a central role in cytokine production and in the generation of antiviral immunity. The relative contributions of different Toll-like receptors (TLRs) in the innate immune response during central nervous system infection with HSV-1 have not been fully characterized.

Requirement of UNC93B1 reveals a critical role for TLR7 in host resistance to primary infection with Trypanosoma cruzi.

UNC93B1 associates with TLR3, 7, and 9, mediating their translocation from the endoplasmic reticulum to the endolysosome, thus allowing proper activation by microbial nucleic acids. We found that the triple-deficient 3d mice, which lack functional UNC93B1 as well as functional endosomal TLRs, are highly susceptible to infection with Trypanosoma cruzi. The enhanced parasitemia and mortality in 3d animals were associated with impaired proinflammatory response, including reduced levels of IL-12p40 and IFN-γ.

The critical role of IL-1 receptor-associated kinase 4-mediated NF-κB activation in modified low-density lipoprotein-induced inflammatory gene expression and atherosclerosis.

Exciting discoveries related to IL-1R/TLR signaling in the development of atherosclerosis plaque have triggered intense interest in the molecular mechanisms by which innate immune signaling modulates the onset and development of atherosclerosis. Previous studies have clearly shown the definitive role of proinflammatory cytokine IL-1 in the development of atherosclerosis. Recent studies have provided direct evidence supporting a link between innate immunity and atherogenesis.

UNC93B1 mediates host resistance to infection with Toxoplasma gondii.

UNC93B1 associates with Toll-Like Receptor (TLR) 3, TLR7 and TLR9, mediating their translocation from the endoplasmic reticulum to the endolysosome, hence allowing proper activation by nucleic acid ligands. We found that the triple deficient '3d' mice, which lack functional UNC93B1, are hyper-susceptible to infection with Toxoplasma gondii. We established that while mounting a normal systemic pro-inflammatory response, i.

Discovery of a novel TLR2 signaling inhibitor with anti-viral activity.

Blockade of Toll-like receptor (TLR)-mediated inflammatory responses represents a new approach in the development of anti-inflammation therapeutics. In the present study, we have screened for TLR2-mediated inflammation inhibitors from small molecule compound libraries using a sensitive cell line stably expressing TLR2, CD14, and an NF-kappaB-driven-luciferase reporter gene. Lymphocytic choriomeningitis virus (LCMV) was used as a virus model.

Induction and inhibition of type I interferon responses by distinct components of lymphocytic choriomeningitis virus.

Type I interferons (IFNs) play a critical role in the host defense against viruses. Lymphocytic choriomeningitis virus (LCMV) infection induces robust type I IFN production in its natural host, the mouse. However, the mechanisms underlying the induction of type I IFNs in response to LCMV infection have not yet been clearly defined.

Inhibitor of growth-4 promotes IkappaB promoter activation to suppress NF-kappaB signaling and innate immunity.

Ing4 is a member of the inhibitor of growth (ING) family of chromatin-modifying proteins. Biochemical experiments indicate that Ing4 is a subunit of the HB01-JADE-hEAF6 histone acetyltransferase complex responsible for most nucleosomal histone H4 acetylation in eukaryotes, and transfection studies suggest that Ing4 may regulate a wide variety of cellular processes, including DNA repair, apoptosis, cell-cycle regulation, metastasis, angiogenesis, and tumor suppression. However, in vivo evidence for a physiological role for Ing4 in cell-growth regulation is lacking.

Complement receptor 1 expression on mouse erythrocytes mediates clearance of Streptococcus pneumoniae by immune adherence.

Complement-containing immune complexes can be presented to phagocytes by human erythrocytes bearing complement receptor 1 (CR1). Although this has long been assumed to be a mechanism by which humans are able to protect themselves from "extracellular" bacteria such as pneumococci, there is little direct evidence. In these studies we have investigated this question by comparing results for erythrocytes from transgenic mice expressing human CR1 on their erythrocytes to the results for wild-type mouse erythrocytes that do not express CR1.

Mutations in bone marrow-derived stromal stem cells unmask latent malignancy.

Neoplastic epithelia may remain dormant and clinically unapparent in human patients for decades. Multiple risk factors including mutations in tumor cells or the stromal cells may affect the switch from dormancy to malignancy. Gene mutations, including p53 mutations, within the stroma of tumors are associated with a worse clinical prognosis; however, it is not known if these stromal mutations can promote tumors in genetically at-risk tissue.

MDA5 and MAVS mediate type I interferon responses to coxsackie B virus.

Coxsackie B viruses (CVB) are enteroviruses that have been associated with a variety of human diseases, including myocarditis. In the present study, we found that MDA5 and its adaptor molecule MAVS are critical for type I interferon responses to CVB, since the absence of either MAVS or MDA5 leads to deficient type I interferon production and early mortality in mice infected with CVB. Pancreatic and hepatic necrosis were observed on histopathological examination of MAVS and MDA5 knockout mice infected with CVB.

Human erythrocytes bind and inactivate type 5 adenovirus by presenting Coxsackie virus-adenovirus receptor and complement receptor 1.

Type 5 adenovirus (Ad5) is a human pathogen that has been widely developed for therapeutic uses, with only limited success to date. We report here the novel finding that human erythrocytes present Coxsackie virus-adenovirus receptor (CAR) providing an Ad5 sequestration mechanism that protects against systemic infection. Interestingly, erythrocytes from neither mice nor rhesus macaques present CAR.

MyD88 intrinsically regulates CD4 T-cell responses.

Myeloid differentiation factor 88 (MyD88) is an essential adaptor protein in the Toll-like receptor-mediated innate signaling pathway, as well as in interleukin-1 receptor (IL-1R) and IL-18R signaling. The importance of MyD88 in the regulation of innate immunity to microbial pathogens has been well demonstrated. However, its role in regulating acquired immunity to viral pathogens and neuropathogenesis is not entirely clear.

Respiratory syncytial virus activates innate immunity through Toll-like receptor 2.

Respiratory syncytial virus (RSV) is a common cause of infection that is associated with a range of respiratory illnesses, from common cold-like symptoms to serious lower respiratory tract illnesses such as pneumonia and bronchiolitis. RSV is the single most important cause of serious lower respiratory tract illness in children <1 year of age. Host innate and acquired immune responses activated following RSV infection have been suspected to contribute to RSV disease.

Toll-like receptor-mediated activation of neutrophils by influenza A virus.

Influenza virus infection of the respiratory tract is characterized by a neutrophil infiltrate accompanied by inflammatory cytokine and chemokine production. We and others have reported that Toll-like receptor (TLR) proteins are present on human neutrophils and that granulocyte-macrophage colony-stimulating factor (GM-CSF) treatment enhances IL-8 (CXCL8) secretion in response to stimulation with TLR ligands. We demonstrate that influenza virus can induce IL-8 and other inflammatory cytokines from GM-CSF-primed human neutrophils.

Lymphocytic choriomeningitis virus (LCMV) infection of CNS glial cells results in TLR2-MyD88/Mal-dependent inflammatory responses.

In response to invading pathogens, Toll-like receptors (TLR) play a critical role in the initiation of the innate immune response, which can be either beneficial or detrimental to the host. In the present study, we demonstrated that central nervous system (CNS) glial cells are activated by Lymphocytic Choriomeningitis Virus (LCMV) in a TLR2-MyD88/Mal-dependent manner. Specifically, in response to LCMV, both astrocytes and microglial cells isolated from wild-type (WT) mice produced chemokines, such as MCP-1, RANTES and TNF-alpha.

Role of MyD88 in route-dependent susceptibility to vesicular stomatitis virus infection.

TLRs are important components of the innate immune response. The role of the TLR signaling pathway in host defense against a natural viral infection has been largely unexplored. We found that mice lacking MyD88, an essential adaptor protein in TLR signaling pathway, were extremely sensitive to intranasal infection with vesicular stomatitis virus, and this susceptibility was dose dependent.

Trefoil family factor 2 is expressed in murine gastric and immune cells and controls both gastrointestinal inflammation and systemic immune responses.

Trefoil family factor 2 (TFF2), also known as spasmolytic peptide, is a low-molecular-weight protein that is upregulated in gastric tissues infected with Helicobacter or having other inflammatory conditions, but a precise function is yet to be elucidated. The role of TFF2 in the development of gastritis, colitis, and inflammatory cytokine responses was examined both in vivo and in vitro using wild-type and TFF2 knockout mice. TFF2 knockout and wild-type mice were infected with Helicobacter felis (H.

The erythrocyte viral trap: transgenic expression of viral receptor on erythrocytes attenuates coxsackievirus B infection.

Viruses rely on attachment to specific cell surface receptors to infect host cells. Selective expression of viral receptors has the potential to attenuate infection of susceptible tissues by redirecting virus to cells that cannot support viral replication. We propose that erythrocytes are an ideal instrument for this strategy, because they are present in vast numbers, permeate every organ, and cannot serve as hosts for viral propagation.

Coxsackievirus and adenovirus receptor is essential for cardiomyocyte development.

The coxsackievirus and adenovirus receptor (CAR) is a transmembrane protein that is known to be a site of viral attachment and entry, but its physiologic functions are undefined. CAR expression is maximal in neonates and wanes rapidly after birth in organs such as heart, muscle, and brain, suggesting that CAR plays a role in the development of these tissues. Here, we show that CAR deficiency resulted in an embryonic lethal condition associated with cardiac defects.

MyD88 is critical for the development of innate and adaptive immunity during acute lymphocytic choriomeningitis virus infection.

We investigated the roles of Toll-like receptor 2 (TLR2) and myeloid differentiation factor 88 (MyD88) in the course of a lymphocytic choriomeningitis virus (LCMV) infection and revealed the following: (i) studies of transfected cells and murine peritoneal macrophages demonstrated that TLR2 and MyD88 are essential for the initial pro-inflammatory cytokine response (human IL-8, mouse IL-6) to LCMV; (ii) TLR2 knockout (KO) mice and MyD88 KO mice challenged with LCMV produced less IL-6 and monocyte chemotactic protein-1 in the serum than wild-type mice; (iii) in contrast to inflammatory cytokines, the production of type 1 IFN (IFN-alpha) in response to LCMV was MyD88 independent; (iv) MyD88 plays an essential role in antiviral CD8(+) T cell responses, CD8(+) T cells in MyD88 KO mice were defective in their expression of intracellular antiviral cytokines; and (v) the failure of MyD88 KO mice to activate CD8(+) T cells was accompanied by persistent viral infection in MyD88 KO mice. We demonstrate that TLR-mediated responses are important in the innate immune response to LCMV and that MyD88 is essential for the control of the LCMV infection and the maturation/activation of virus-specific CD8(+) T cells.