Type I interferon is required for T helper (Th) 2 induction by dendritic cells

Type 2 inflammation is a defining feature of infection with parasitic worms (helminths), as well as being responsible for widespread suffering in allergies. However, the precise mechanisms involved in T helper (Th) 2 polarization by dendritic cells (DCs) are currently unclear. We have identified a previously unrecognized role for type I IFN (IFN‐I) in enabling this process. An IFN‐I signature was evident in DCs responding to the helminth Schistosoma mansoni or the allergen house dust mite (HDM). Further, IFN‐I signaling was required for optimal DC phenotypic activation in response to helminth antigen (Ag), and efficient migration to, and localization with, T cells in the draining lymph node (dLN). Importantly, DCs generated from Ifnar1^?/? mice were incapable of initiating Th2 responses in vivo. These data demonstrate for the first time that the influence of IFN‐I is not limited to antiviral or bacterial settings but also has a central role to play in DC initiation of Th2 responses.     

The role of type I interferon production by dendritic cells in host defense

Type I interferons (IFN) and dendritic cells (DC) share an overlapping history, with rapidly accumulating evidence for vital roles for both production of type 1 IFN by DC and the interaction of this IFN both with DC and components of the innate and adaptive immune responses. Within the innate immune response, the plasmacytoid DC (pDC) are the "professional" IFN producing cells, expressing specialized toll-like receptors (TLR7 and -9) and high constitutive expression of IRF-7 that allow them to respond to viruses with rapid and extremely robust IFN production; following activation and production of IFN, the pDC subsequently mature into antigen presenting cells that help to shape the adaptive immune response. However, like most cells in the body, the myeloid or conventional DC (mDC or cDC) also produce type I IFNs, albeit typically at a lower level than that observed with pDC, and this IFN is also important in innate and adaptive immunity induced by these classic antigen presenting cells. These two major DC subsets and their IFN products interact both with each other as well as with NK cells, monocytes, T helper cells, T cytotoxic cells, T regulatory cells and B cells to orchestrate the early immune response. This review discusses some of the converging history of DC and IFN as well as mechanisms for IFN induction in DC and the effects of this IFN on the developing immune response.     

Type I interferon receptor controls B-cell expression of nucleic acid-sensing Toll-like receptors and autoantibody production in a murine model of lupus

Introduction  

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the production of high-titer IgG autoantibodies directed against nuclear autoantigens. Type I interferon (IFN-I) has been shown to play a pathogenic role in this disease. In the current study, we characterized the role of the IFNAR2 chain of the type I IFN (IFN-I) receptor in the targeting of nucleic acid-associated autoantigens and in B-cell expression of the nucleic acid-sensing Toll-like receptors (TLRs), TLR7 and TLR9, in the pristane model of lupus.     

Nonlinear laser photomodification of nucleic acids induced by intercalating dyes

Results of a cycle of investigations of two-quantum affinity modification of nucleic acids (NA) are presented. The modification is induced by laser excitation of chromophoric molecules which are in intercalative complexes with NA. The following subjects are considered: theoretical basis of the two-quantum affinity modification: experimental investigation of nonlinear scission of DNA; theory and experiment on the light--induced diffusion of DNA. The latter is an effect which accompanies the scission and allows one to obtain information on it. The modification specificity and universality in a dye type are established experimentally. Influence of free radicals, oxygen, heating and hydrodynamical phenomena in bulk are excluded. The modification has been shown to be dependent on NA structure (secondary and tertiary) and to provide information on it. Total aggregate of the data obtained is in agreement with the suggested modification mechanism which is based on the radiationless transfer of two-quantum excitation energy from the chromophore to NA.     

Type I gamma phosphatidylinositol phosphate kinase is required for EGF-stimulated directional cell migration

Phosphatidylinositol 4,5-bisphosphate (PI4,5P(2)) modulates a plethora of cytoskeletal interactions that control the dynamics of actin assembly and, ultimately, cell migration. We show that the type Igamma phosphatidylinositol phosphate kinase 661 (PIPKIgamma661), an enzyme that generates PI4,5P(2), is required for growth factor but not G protein-coupled receptor-stimulated directional migration. By generating PI4,5P(2) and regulating talin assembly, PIPKIgamma661 modulates nascent adhesion formation at the leading edge to facilitate cell migration. The epidermal growth factor (EGF) receptor directly phosphorylates PIPKIgamma661 at tyrosine 634, and this event is required for EGF-induced migration. This phosphorylation regulates the interaction between PIPKIgamma661 and phospholipase Cgamma1 (PLCgamma1, an enzyme previously shown to be involved in the regulation of EGF-stimulated migration). Our results suggest that phosphorylation events regulating specific PIPKIgamma661 interactions are required for growth factor-induced migration. These interactions in turn define the spatial and temporal generation of PI4,5P(2) and derived messengers required for directional migration.     

Functional interferon system is required for clearance of lassa virus

Lassa virus (LASV) is the causative agent of Lassa hemorrhagic fever (LF) in humans, a deadly disease endemic to West Africa that results in 5,000 to 10,000 deaths annually. Here we present results demonstrating that functional type I and type II interferon (IFN) signaling is required for efficient control of LASV dissemination and clearance.     

Type I interferon as a stimulus for cross-priming

Type I interferon (IFN-alpha/beta) is induced rapidly by infection and is well recognised for its crucial role in innate defence. However, it is evident that IFN-alpha/beta also serves as a signal for the generation of adaptive immune responses. In this review, we focus on the involvement of IFN-alpha/beta in the induction of CD8+ T cell responses by cross-priming.     

Autophagy in Drosophila ovaries is induced by starvation and is required for oogenesis

Autophagy, an evolutionarily conserved lysosome-mediated degradation, promotes cell survival under starvation and is controlled by insulin/target of rapamycin (TOR) signaling. In Drosophila, nutrient depletion induces autophagy in the fat body. Interestingly, nutrient availability and insulin/TOR signaling also influence the size and structure of Drosophila ovaries, however, the role of nutrient signaling and autophagy during this process remains to be elucidated. Here, we show that starvation induces autophagy in germline cells (GCs) and in follicle cells (FCs) in Drosophila ovaries. This process is mediated by the ATG machinery and involves the upregulation of Atg genes. We further demonstrate that insulin/TOR signaling controls autophagy in FCs and GCs. The analysis of chimeric females reveals that autophagy in FCs, but not in GCs, is required for egg development. Strikingly, when animals lack Atg gene function in both cell types, ovaries develop normally, suggesting that the incompatibility between autophagy-competent GCs and autophagy-deficient FCs leads to defective egg development. As egg morphogenesis depends on a tightly linked signaling between FCs and GCs, we propose a model in which autophagy is required for the communication between these two cell types. Our data establish an important function for autophagy during oogenesis and contributes to the understanding of the role of autophagy in animal development.     

PERP,a host tetraspanning membrane protein,is required for Salmonella‐induced inflammation

Salmonella enterica Typhimurium induces intestinal inflammation through the activity of type III secreted effector (T3SE) proteins. Our prior results indicate that the secretion of the T3SE SipA and the ability of SipA to induce epithelial cell responses that lead to induction of polymorphonuclear transepithelial migration are not coupled to its direct delivery into epithelial cells from Salmonella. We therefore tested the hypothesis that SipA interacts with a membrane protein located at the apical surface of intestinal epithelial cells. Employing a split ubiquitin yeast‐two‐hybrid screen, we identified the tetraspanning membrane protein, p53 effector related to PMP‐22 (PERP), as a SipA binding partner. SipA and PERP appear to have intersecting activities as we found PERP to be involved in proinflammatory pathways shown to be regulated by SipA. In sum, our studies reveal a critical role for PERP in the pathogenesis of S. Typhimurium, and for the first time demonstrate that SipA, a T3SE protein, can engage a host protein at the epithelial surface.     

Cytostasis is required for IL-1 induced nitric oxide production in transformed hamster fibroblasts

Interleukin-1 (IL-1) is known to inhibit proliferation in some tumor cells. This proinflammatory cytokine also induces nitric oxide production in a variety of cell types. In the present studies we determined if nitric oxide is involved in IL-1 induced growth inhibition in spontaneously transformed hamster embryonic fibroblasts (STHE cells). Both IL-1α and IL-1β were found to stimulate nitric oxide production and to reduce ³H-thymidine (TdR) incorporation in high density cultures of STHE cells. However, maximal cytostasis was observed at least 24 h before significant amounts of nitric oxide accumulated in the cultures. In addition, doses of IL-1 which were too low to stimulate nitric oxide synthesis were effective in inducing cytostasis. Furthermore, in low density cultures of STHE cells, IL-1 inhibited DNA synthesis without inducing nitric oxide production. The nitric oxide synthase inhibitor N^G-monomethyl-l-arginine (L-NMMA) had no effect on proliferation of cells plated at low density. In contrast, L-NMMA treatment resulted in a 40–60% reduction in IL-1 induced cytostasis in high density cultures. Neutralizing antibodies to IL-1 were found to completely block IL-1 induced cytostasis and nitric oxide production in cells plated at both densities. Although anti-IL-1α and anti-lL-1β antibodies were highly specific and did not cross react, anti-tumor necrosis factor-α (TNF-α) antibody was able to partially suppress activation of STHE cells by both IL-1α and IL-1β. These data suggest a potential involvement of endogenous TNF-α in IL-1 induced cytostasis and nitric oxide production. Exponentially growing STHE cells produced six-times less nitric oxide than non-proliferating cells. A ten-fold excess of l-arginine was found to stimulate nitric oxide synthesis, an action that was independent of the rate of cellular proliferation. Taken together these data suggest that nitric oxide is not a major mediator of IL-1 induced cytostasis in STHE cells. Moreover, cytostasis appears to be required for nitric oxide synthesis in these cells. © 1996 Wiley-Liss, Inc.     

IL-22 production is regulated by IL-23 during Listeria monocytogenes infection but is not required for bacterial clearance or tissue protection

Listeria monocytogenes (LM) is a gram-positive bacterium that is a common contaminant of processed meats and dairy products. In humans, ingestion of LM can result in intracellular infection of the spleen and liver, which can ultimately lead to septicemia, meningitis, and spontaneous abortion. Interleukin (IL)-23 is a cytokine that regulates innate and adaptive immune responses by inducing the production of IL-17A, IL-17F, and IL-22. We have recently demonstrated that the IL-23/IL-17 axis is required for optimal recruitment of neutrophils to the liver, but not the spleen, during LM infection. Furthermore, these cytokines are required for the clearance of LM during systemic infection. In other infectious models, IL-22 induces the secretion of anti-microbial peptides and protects tissues from damage by preventing apoptosis. However, the role of IL-22 has not been thoroughly investigated during LM infection. In the present study, we show that LM induces the production of IL-22 in vivo. Interestingly, IL-23 is required for the production of IL-22 during primary, but not secondary, LM infection. Our findings suggest that IL-22 is not required for clearance of LM during primary or secondary infection, using both systemic and mucosal models of infection. IL-22 is also not required for the protection of LM infected spleens and livers from organ damage. Collectively, these data indicate that IL-22 produced during LM infection must play a role other than clearance of LM or protection of tissues from pathogen- or immune-mediated damage.     

Lactosylceramide is required in apoptosis induced by N-Smase

Lactosylceramide (LacCer) is a member of the glycosphingolipid family which has been recently recognized as a signaling intermediate in the regulation of cell proliferation and cell adhesion. In this paper, we present our studies pointing to a potential role of LacCer in inducing apoptosis. In our studies we employed a human osteosarcoma cell line MG-63 (wild type, WT) and a neutral sphingomyelinase (N-SMase) deficient cell line CC derived from MG-63 (mutant) cells. We observed that WT cells were highly sensitive to tumor necrosis factor-α (TNF-α), ceramide and LacCer-induced apoptosis. In contrast, the mutant cells were insensitive to TNF-α-induced apoptosis as they did not generate ceramide and LacCer. However, the exogenous supply of ceramide and/or LacCer rendered the mutant cells apoptotic. Interestingly, preincubation of cells with D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP), an inhibitor of glucosylceramide synthase and lactosylceramide synthase, abrogated ceramide-induced apoptosis but not LacCer-induced apoptosis in both WT cells and the mutant cells. Moreover, TNF-α and LacCer-induced apoptosis required the generation of reactive oxygen species (ROS) in WT cells. However, since mutant cells did not produce significant amounts of LacCer and ROS in response to TNF-α treatment they are insensitive to TNF-α-induced apoptosis. In summary, our studies suggest that TNF-α-induced N-SMase activation and production of ceramide is required to activate the apoptosis pathway in human osteosarcoma cells. But it is not sufficient to induce apoptosis. Rather, the conversion of ceramide to LacCer and ROS generation are critical for apoptosis.     

Murine dendritic cell type I IFN production induced by human IgG-RNA immune complexes is IFN regulatory factor (IRF)5 and IRF7 dependent and is required for IL-6 production

Dendritic cell (DC) activation by nucleic acid-containing IgG complexes is implicated in systemic lupus erythematosus (SLE) pathogenesis. However, it has been difficult to definitively examine the receptors and signaling pathways by which this activation is mediated. Because mouse FcgammaRs recognize human IgG, we hypothesized that IgG from lupus patients might stimulate mouse DCs, thereby facilitating this analysis. In this study, we show that sera and purified IgG from lupus patients activate mouse DCs to produce IFN-alpha, IFN-beta, and IL-6 and up-regulate costimulatory molecules in a FcgammaR-dependent manner. This activation is only seen in sera with reactivity against ribonucleoproteins and is completely dependent on TLR7 and the presence of RNA. As anticipated, IFN regulatory factor (IRF)7 is required for IFN-alpha and IFN-beta production. Unexpectedly, however, IRF5 plays a critical role in IFN-alpha and IFN-beta production induced not only by RNA-containing immune complexes but also by conventional TLR7 and TLR9 ligands. Moreover, DC production of IL-6 induced by these stimuli is dependent on a functional type I IFNR, indicating the need for a type I IFN-dependent feedback loop in the production of inflammatory cytokines. This system may also prove useful for the study of receptors and signaling pathways used by immune complexes in other human diseases.     

An antioxidant system required for host protection against gut infection in Drosophila

A fundamental question that applies to all organisms is how barrier epithelia efficiently manage continuous contact with microorganisms. Here, we show that in Drosophila an extracellular immune-regulated catalase (IRC) mediates a key host defense system that is needed during host-microbe interaction in the gastrointestinal tract. Strikingly, adult flies with severely reduced IRC expression show high mortality rates even after simple ingestion of microbe-contaminated foods. However, despite the central role that the NF-kappaB pathway plays in eliciting antimicrobial responses, NF-kappaB pathway mutant flies are totally resistant to such infections. These results imply that homeostasis of redox balance by IRC is one of the most critical factors affecting host survival during continuous host-microbe interaction in the gastrointestinal tract.     

Inhibition of virus-induced diabetes mellitus by interferon is influenced by the host strain

The diabetogenic variant of encephalomyocarditis virus (EMC-D) induces a diabetes-like syndrome in certain strains of mice. A study was done to determine if virus-induced diabetes could be prevented by interferon (IFN). It was found that the production of diabetes by EMC-D was blocked by either IFN beta or a variety of IFN-inducers in SWR/J, but not ICR Swiss mice. The replication of EMC-D in cell culture was inhibited by IFN beta. It is concluded that the response of pancreatic beta cells to the protective effect of IFN, is probably under genetic control.