Immunology and Infectious Disease Commons^™

Dual Engagement Of The Nlrp3 And Aim2 Inflammasomes By Plasmodium-Derived Hemozoin And Dna During Malaria, Parisa Kalantari, Rosane B. Deoliveira, Jennie Chan, Yolanda Corbett, Vijay A. K. Rathinam, Andrea Stutz, Eicke Latz, Ricardo T. Gazzinelli, Douglas T. Golenbock, Katherine A. Fitzgerald

Katherine A. Fitzgerald

Hemozoin (Hz) is the crystalline detoxification product of hemoglobin in Plasmodium-infected erythrocytes. We previously proposed that Hz can carry plasmodial DNA into a subcellular compartment that is accessible to Toll-like receptor 9 (TLR9), inducing an inflammatory signal. Hz also activates the NLRP3 inflammasome in primed cells. We found that Hz appears to colocalize with DNA in infected erythrocytes, even before RBC rupture or phagolysosomal digestion. Using synthetic Hz coated in vitro with plasmodial genomic DNA (gDNA) or CpG oligodeoxynucleotides, we observed that DNA-complexed Hz induced TLR9 translocation, providing a priming and an activation signal for inflammasomes. After phagocytosis, Hz and …

Serine/Threonine Acetylation Of Tgfbeta-Activated Kinase (Tak1) By Yersinia Pestis Yopj Inhibits Innate Immune Signaling, Nicholas Paul Paquette, Joseph E. Conlon, Charles R. Sweet, Florentina Rus, Lindsay Wilson, Andrea J. Pereira, Charles V. Rosadini, Nadege Goutagny, Alexander N. R. Weber, William S. Lane, Scott A. Shaffer, Stephanie Maniatis, Katherine A. Fitzgerald, Lynda M. Stuart, Neal S. Silverman

Katherine A. Fitzgerald

The Gram-negative bacteria Yersinia pestis, causative agent of plague, is extremely virulent. One mechanism contributing to Y. pestis virulence is the presence of a type-three secretion system, which injects effector proteins, Yops, directly into immune cells of the infected host. One of these Yop proteins, YopJ, is proapoptotic and inhibits mammalian NF-kappaB and MAP-kinase signal transduction pathways. Although the molecular mechanism remained elusive for some time, recent work has shown that YopJ acts as a serine/threonine acetyl-transferase targeting MAP2 kinases. Using Drosophila as a model system, we find that YopJ inhibits one innate immune NF-kappaB signaling pathway (IMD) but not …

Pattern Recognition Receptors And The Innate Immune Response To Viral Infection, Mikayla R. Thompson, John J. Kaminski Iii, Evelyn A. Kurt-Jones, Katherine A. Fitzgerald

Katherine A. Fitzgerald

The innate immune response to viral pathogens is critical in order to mobilize protective immunity. Cells of the innate immune system detect viral infection largely through germline-encoded pattern recognition receptors (PRRs) present either on the cell surface or within distinct intracellular compartments. These include the Toll-like receptors (TLRs), the retinoic acid-inducble gene I-like receptors (RLRs), the nucleotide oligomerization domain-like receptors (NLRs, also called NACHT, LRR and PYD domain proteins) and cytosolic DNA sensors. While in certain cases viral proteins are the trigger of these receptors, the predominant viral activators are nucleic acids. The presence of viral sensing PRRs in multiple …

Superior Immunogenicity Of Inactivated Whole Virus H5n1 Influenza Vaccine Is Primarily Controlled By Toll-Like Receptor Signalling, Felix Geeraedts, Nadege Goutagny, Veit Hornung, Martina Severa, Aalzen De Haan, Judity Pool, Jan Wilschut, Katherine A. Fitzgerald, Anke Huckriede

Katherine A. Fitzgerald

In the case of an influenza pandemic, the current global influenza vaccine production capacity will be unable to meet the demand for billions of vaccine doses. The ongoing threat of an H5N1 pandemic therefore urges the development of highly immunogenic, dose-sparing vaccine formulations. In unprimed individuals, inactivated whole virus (WIV) vaccines are more immunogenic and induce protective antibody responses at a lower antigen dose than other formulations like split virus (SV) or subunit (SU) vaccines. The reason for this discrepancy in immunogenicity is a long-standing enigma. Here, we show that stimulation of Toll-like receptors (TLRs) of the innate immune system, …

Functional Regulation Of Myd88-Activated Interferon Regulatory Factor 5 By K63-Linked Polyubiquitination, Mumtaz Yaseen Balkhi, Katherine A. Fitzgerald, Paula M. Pitha

Katherine A. Fitzgerald

Interferon regulatory factor 5 (IRF-5) plays an important role in the innate antiviral and inflammatory response. Specific IRF-5 haplotypes are associated with dysregulated expression of type I interferons and predisposition to autoimmune disorders. IRF-5 is activated by Toll-like receptor 7 (TLR7) and TLR9 via the MyD88 pathway, where it interacts with both MyD88 and the E3 ubiquitin ligase, TRAF6. To understand the role of these interactions in the regulation of IRF-5, we examined the role of ubiquitination and showed that IRF-5 is subjected to TRAF6-mediated K63-linked ubiquitination, which is important for IRF-5 nuclear translocation and target gene regulation. We show …

Dengue Virus Nonstructural Protein Ns5 Induces Interleukin-8 Transcription And Secretion, Carey L. Medin, Katherine A. Fitzgerald, Alan L. Rothman

Katherine A. Fitzgerald

Elevated circulating levels of chemokines have been reported in patients with dengue fever and are proposed to contribute to the pathogenesis of dengue disease. To establish in vitro models for chemokine induction by dengue 2 virus (DEN2V), we studied a variety of human cell lines and primary cells. DEN2V infection of HepG2 and primary dendritic cells induced the production of interleukin-8 (IL-8), RANTES, MIP-1alpha, and MIP-1beta, whereas only IL-8 and RANTES were induced following dengue virus infection of HEK293 cells. Chemokine secretion was accompanied by an increase in steady-state mRNA levels. No chemokine induction was observed in HEK293 cells treated …

Detecting Microrna Activity From Gene Expression Data, Stephen F. Madden, Susan B. Carpenter, Ian B. Jeffery, Harry Bjorkbacka, Katherine A. Fitzgerald, Luke A. J. O'Neill, Desmond G. Higgins

Katherine A. Fitzgerald

BACKGROUND: MicroRNAs (miRNAs) are non-coding RNAs that regulate gene expression by binding to the messenger RNA (mRNA) of protein coding genes. They control gene expression by either inhibiting translation or inducing mRNA degradation. A number of computational techniques have been developed to identify the targets of miRNAs. In this study we used predicted miRNA-gene interactions to analyse mRNA gene expression microarray data to predict miRNAs associated with particular diseases or conditions.

RESULTS: Here we combine correspondence analysis, between group analysis and co-inertia analysis (CIA) to determine which miRNAs are associated with differences in gene expression levels in microarray data sets. …

Lps-Tlr4 Signaling To Irf-3/7 And Nf-Kappab Involves The Toll Adapters Tram And Trif, Katherine A. Fitzgerald, Daniel C. Rowe, Betsy J. Barnes, Daniel R. Caffrey, Alberto Visintin, Eicke Latz, Brian G. Monks, Paula M. Pitha, Douglas T. Golenbock

Katherine A. Fitzgerald

Toll-IL-1-resistance (TIR) domain-containing adaptor-inducing IFN-beta (TRIF)-related adaptor molecule (TRAM) is the fourth TIR domain-containing adaptor protein to be described that participates in Toll receptor signaling. Like TRIF, TRAM activates interferon regulatory factor (IRF)-3, IRF-7, and NF-kappaB-dependent signaling pathways. Toll-like receptor (TLR)3 and 4 activate these pathways to induce IFN-alpha/beta, regulated on activation, normal T cell expressed and secreted (RANTES), and gamma interferon-inducible protein 10 (IP-10) expression independently of the adaptor protein myeloid differentiation factor 88 (MyD88). Dominant negative and siRNA studies performed here demonstrate that TRIF functions downstream of both the TLR3 (dsRNA) and TLR4 (LPS) signaling pathways, whereas the …

The Induction Of Macrophage Gene Expression By Lps Predominantly Utilizes Myd88-Independent Signaling Cascades, Harry Bjorkbacka, Katherine A. Fitzgerald, Francois Huet, Xiaoman Li, James A. Gregory, Melinda Lee, Christine M. Ordija, Nicole E. Dowley, Douglas T. Golenbock, Mason W. Freeman

Katherine A. Fitzgerald

Myeloid differentiation protein-88 (MyD88) is a signal adaptor protein required for cytokine production following engagement of Toll-like receptors (TLRs) by their cognate ligands. Activation of both TLR-3 and TLR-4, however, can engage signaling events independent of MyD88 expression. The relative importance of these MyD88-dependent and -independent signaling pathways in the macrophage response to lipopolysaccharide (LPS) is unknown. Here we define these events using microarray expression profiling of LPS-stimulated macrophages taken from MyD88-null and wild-type mice. Of the 1,055 genes found to be LPS responsive, only 21.5% were dependent on MyD88 expression, with MyD88-independent genes constituting 74.7% of the genetic response. …