bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sporozoite-Mediated Hepatocyte Wounding Limits Plasmodium Parasite Development via MyD88-Mediated NF-κB Activation and Inducible NO Synthase Expression
Authors: Torgler Ralph , Bongfen Silayuv E. , Romero Jackeline C. , Tardivel Aubry , Thome Margot , Corradin Giampietro 
Published: April 2014

Abstract
Plasmodium sporozoites traverse several host cells before infecting hepatocytes. In the process, the plasma membranes of the cells are ruptured, resulting in the release of cytosolic factors into the microenvironment. This released endogenous material is highly stimulatory/immunogenic and can serve as a danger signal initiating distinct responses in various cells. Thus, our study aimed at characterizing the effect of cell material leakage during Plasmodium infection on cultured mouse primary hepatocytes and HepG2 cells. We observed that wounded cell-derived cytosolic factors activate NF-κB, a main regulator of host inflammatory responses, in cells bordering wounded cells, which are potential host cells for final parasite infection. This activation of NF-κB occurred shortly after infection and led to a reduction of infection load in a time-dependent manner in vitro and in vivo, an effect that could be reverted by addition of the specific NF-κB inhibitor BAY11-7082. Furthermore, no NF-κB activation was observed when Spect−/− parasites, which are devoid of hepatocyte traversing properties, were used. We provide further evidence that NF-κB activation causes the induction of inducible NO synthase expression in hepatocytes, and this is, in turn, responsible for a decrease in Plasmodium-infected hepatocytes. Furthermore, primary hepatocytes from MyD88−/− mice showed no NF-κB activation and inducible NO synthase expression upon infection, suggesting a role of the Toll/IL-1 receptor family members in sensing cytosolic factors. Indeed, lack of MyD88 significantly increased infection in vitro and in vivo. Thus, host cell wounding due to parasite migration induces inflammation which limits the extent of parasite infection.
Lack of Toll IL-1R8 Exacerbates Th17 Cell Responses in Fungal Infection
Authors: Bozza Silvia , Zelante Teresa , Moretti Silvia , Bonifazi Pierluigi , DeLuca Antonella , D’Angelo Carmen , Giovannini Gloria , Garlanda Cecilia , Boon Louis , Bistoni Francesco , Puccetti Paolo , Mantovani Alberto , Romani Luigina 
Published: April 2014

Abstract
TLRs contribute to the inflammatory response in fungal infections. Although inflammation is an essential component of the protective response to fungi, its dysregulation may significantly worsen fungal diseases. In this study, we tested the hypothesis that Toll IL-1R8 (TIR8)/single Ig IL-1-related receptor, a member of the IL-1R family acting as a negative regulator of TLR/IL-1R signaling, affects TLR responses in fungal infections. Genetically engineered Tir8−/− mice were assessed for inflammatory and adaptive Th cell responses to Candida albicans and Aspergillus fumigatus. Inflammatory pathology and susceptibility to infection were higher in Tir8−/− mice and were causally linked to the activation of the Th17 pathway. IL-1R signaling was involved in Th17 cell activation by IL-6 and TGF-β in that limited inflammatory pathology and relative absence of Th17 cell activation were observed in IL-1RI−/− mice. These data demonstrate that TIR8 is required for host resistance to fungal infections and that it functions to negatively regulate IL-1-dependent activation of inflammatory Th17 responses. TIR8 may contribute toward fine-tuning the balance between protective immunity and immunopathology in infection.
SOCS-1 Protects against Chlamydia pneumoniae-Induced Lethal Inflammation but Hampers Effective Bacterial Clearance
Authors: Yang Tangbin , Stark Patrik , Janik Katrin , Wigzell Hans , Rottenberg Martin E. 
Published: April 2014

Abstract
Suppressor of cytokine signaling 1 (SOCS1) plays a major role in the inhibition of STAT1-mediated responses. STAT1-dependent responses are critical for resistance against infection with Chlamydia pneumoniae. We studied the regulation of expression of SOCS1 and SOCS3, and the role of SOCS1 during infection with C. pneumoniae in mice. Bone marrow-derived macrophages (BMM) and dendritic cells in vitro or lungs in vivo all showed enhanced STAT1-dependent SOCS1 mRNA accumulation after infection with C. pneumoniae. Infection-increased SOCS1 mRNA levels were dependent on IFN-αβ but not on IFN-γ. T or B cells were not required for SOCS1 mRNA accumulation in vivo. Infection-induced STAT1-phosphorylation occurred more rapidly in SOCS1−/− BMM. In agreement, expression of IFN-γ responsive genes, but not IL-1β, IL-6, or TNF-α were relatively increased in C. pneumoniae-infected SOCS1−/− BMM. Surprisingly, C. pneumoniae infection-induced IFN-α, IFN-β, and IFN-γ expression in BMM were attenuated by SOCS1. C. pneumoniae infection of RAG1−/−/SOCS1−/− mice induced a rapid lethal inflammation, accompanied by diminished pulmonary bacterial load and increased levels of iNOS and IDO but not IL-1β, IL-6, or TNF-α mRNA. In summary, C. pneumoniae infection induces a STAT1, IFN-αβ-dependent and IFN-γ independent SOCS1 mRNA accumulation. Presence of SOCS1 controls the infection-induced lethal inflammatory disease but impairs the bacterial control.
Functional CD8+ T Cell Responses in Lethal Ebola Virus Infection
Authors: Bradfute Steven B. , Warfield Kelly L. , Bavari Sina 
Published: April 2014

Abstract
Ebola virus (EBOV) causes highly lethal hemorrhagic fever that leads to death in up to 90% of infected humans. Like many other infections, EBOV induces massive lymphocyte apoptosis, which is thought to prevent the development of a functional adaptive immune response. In a lethal mouse model of EBOV infection, we show that there is an increase in expression of the activation/maturation marker CD44 in CD4+ and CD8+ T cells late in infection, preceding a dramatic rebound of lymphocyte numbers in the blood. Furthermore, we observed both lymphoblasts and apoptotic lymphocytes in spleen late in infection, suggesting that there is lymphocyte activation despite substantial bystander apoptosis. To test whether these activated lymphocytes were functional, we performed adoptive transfer studies. Whole splenocytes from moribund day 7 EBOV-infected animals protected naive animals from EBOV, but not Marburgvirus, challenge. In addition, we observed EBOV-specific CD8+ T cell IFN-γ responses in moribund day 7 EBOV-infected mice, and adoptive transfer of CD8+ T cells alone from day 7 mice could confer protection to EBOV-challenged naive mice. Furthermore, CD8+ cells from day 7, but not day 0, mice proliferated after transfer to infected recipients. Therefore, despite significant lymphocyte apoptosis, a functional and specific, albeit insufficient, adaptive immune response is made in lethal EBOV infection and is protective upon transfer to naive infected recipients. These findings should cause a change in the current view of the ‘impaired’ immune response to EBOV challenge and may help spark new therapeutic strategies to control lethal filovirus disease.
Deoxynucleic Acids from Cryptococcus neoformans Activate Myeloid Dendritic Cells via a TLR9-Dependent Pathway
Authors: Nakamura Kiwamu , Miyazato Akiko , Xiao Gang , Hatta Masumitsu , Inden Ken , Aoyagi Tetsuji , Shiratori Kohei , Takeda Kiyoshi , Akira Shizuo , Saijo Shinobu , Iwakura Yoichiro , Adachi Yoshiyuki , Ohno Naohito , Suzuki Kazuo , Fujita Jiro , Kaku Mitsuo , Kawakami Kazuyoshi 
Published: April 2014

Abstract
The mechanism of host cell recognition of Cryptococcus neoformans, an opportunistic fungal pathogen in immunocompromised patients, remains poorly understood. In the present study, we asked whether the DNA of this yeast activates mouse bone marrow-derived myeloid dendritic cells (BM-DCs). BM-DCs released IL-12p40 and expressed CD40 upon stimulation with cryptococcal DNA, and the response was abolished by treatment with DNase, but not with RNase. IL-12p40 production and CD40 expression were attenuated by chloroquine, bafilomycin A, and inhibitory oligodeoxynucleotides (ODN) that suppressed the responses caused by CpG-ODN. Activation of BM-DCs by cryptococcal DNA was almost completely abrogated in TLR9 gene-disrupted (TLR9−/−) mice and MyD88−/− mice, similar to that by CpG-ODN. In addition, upon stimulation with whole yeast cells of acapsular C. neoformans, TLR9−/− BM-DCs produced a lower amount of IL-12p40 than those from wild-type mice, and TLR9−/− mice were more susceptible to pulmonary infection with this fungal pathogen than wild-type mice, as shown by increased number of live colonies in lungs. Treatment of cryptococcal DNA with methylase resulted in reduced IL-12p40 synthesis by BM-DCs. Furthermore, using a luciferase reporter assay, cryptococcal DNA activated NF-κB in HEK293 cells transfected with the TLR9 gene. Finally, confocal microscopy showed colocalization of fluorescence-labeled cryptococcal DNA with CpG-ODN and the findings merged in part with the distribution of TLR9 in BM-DCs. Our results demonstrate that cryptococcal DNA causes activation of BM-DCs in a TLR9-dependent manner and suggest that the CpG motif-containing DNA may contribute to the development of inflammatory responses after infection with C. neoformans.
Functional Adaptation of Nef to the Immune Milieu of HIV-1 Infection In Vivo
Authors: Lewis Martha J. , Balamurugan Arumugam , Ohno Ayako , Kilpatrick Stephanie , Ng Hwee L. , Yang Otto O. 
Published: April 2014

Abstract
Nef-mediated down-regulation of MHC class I (MHC-I) molecules on HIV-1-infected cells has been proposed to enhance viral persistence through evasion of host CTLs. This conclusion is based largely on demonstrations that Nef from laboratory HIV-1 strains reduces the susceptibility of infected cells to CTL killing in vitro. However, the function and role of Nef-mediated MHC-I down-regulation in vivo have not been well described. To approach this issue, nef quasispecies from chronically HIV-1-infected individuals were cloned into recombinant reporter viruses and tested for their ability to down-regulate MHC-I molecules from the surface of infected cells. The level of function varied widely between individuals, and although comparison to the immunologic parameters of blood CD4+ T lymphocyte count and breadth of the HIV-1-specific CTL response showed positive correlations, no significant correlation was found in comparison to plasma viremia. The ability of in vivo-derived Nef to down-regulate MHC-I predicted the resistance of HIV-1 to suppression by CTL. Taken together, these data demonstrate the functionality of Nef to down-regulate MHC-I in vivo during stable chronic infection, and suggest that this function is maintained by the need of HIV-1 to cope with the antiviral CTL response.
Characterization of Pulmonary T Cell Response to Helper-Dependent Adenoviral Vectors following Intranasal Delivery
Authors: Kushwah Rahul , Cao Huibi , Hu Jim 
Published: April 2014

Abstract
In spite of the extensive research in the field of gene therapy, host immune responses continue to be the major barrier in translating basic research to clinical practice. Helper-dependent adenoviral (HD-Ad) vectors show great potential for pulmonary gene therapy, but the knowledge of pulmonary immune responses toward these vectors is very limited. In this study, we show that HD-Ad vectors are potent stimulators of dendritic cell (DC) maturation, thus leading to stimulation of T cell proliferation with ∼6% of naive CD4+ T cells from pulmonary mediastinal lymph node responding to HD-Ad-treated DCs. In contrast to the belief that HD-Ad vectors are unable to prime adaptive immune response, we show for the first time, through in vivo pulmonary studies in mice, that HD-Ad vectors can prime CD4+ and CD8+ T cell responses in the lung at high and substantially low doses. This indicates cross-presentation of HD-Ad-derived epitopes by DCs to prime CD8+ T cell responses. To assess the basis of pulmonary T cell response against HD-Ad vectors, we examined the response of conventional DCs (cDCs) and plasmacytoid DCs (pDCs) in the lung. In response to HD-Ad delivery, there is induction of maturation in both cDC and pDC subsets, but it is the cDCs, not pDCs, that migrate rapidly to draining lymph nodes within the first 2 days after vector delivery to prime adaptive immune response against these vectors. These findings have implications for development of strategies to prevent adaptive immune responses against gene therapy vectors.
Deviation from a Strong Th1-Dominated to a Modest Th17-Dominated CD4 T Cell Response in the Absence of IL-12p40 and Type I IFNs Sustains Protective CD8 T Cells
Authors: Orgun Nural N. , Mathis Meredith A. , Wilson Christopher B. , Way Sing Sing 
Published: April 2014

Abstract
The differentiation of naive CD4 T cells into specific effector subsets is controlled in large part by the milieu of cytokines present during their initial encounter with Ag. Cytokines that drive differentiation of the newly described Th17 lineage have been characterized in vitro, but the cytokines that prime commitment to this lineage in response to infection in vivo are less clear. Listeria monocytogenes (Lm) induces a strong Th1 response in wild-type mice. By contrast, we demonstrate that in the absence of IL-12p40 (or IFN-γ) and type I IFN receptor signaling, the Th1 Ag-specific CD4 T cell response is virtually abolished and replaced by a relatively low magnitude Th17-dominated response. This Th17 response was dependent on TGF-β and IL-6. Despite this change in CD4 T cell response, neither the kinetics of the CD4 and CD8 T cell responses, the quality of the CD8 T cell response, nor the ability of CD8 T cells to mediate protection were affected. Thus, generation of protective CD8 T cell immunity was resilient to perturbations that replace a strong Th1-dominated to a reduced magnitude Th17-dominated Ag-specific CD4 T cell response.
IFN-β Increases Listeriolysin O-Induced Membrane Permeabilization and Death of Macrophages
Authors: Zwaferink Heather , Stockinger Silvia , Hazemi Parastoo , Lemmens-Gruber Rosa , Decker Thomas 
Published: April 2014

Abstract
Type I IFN (IFN-I) signaling is detrimental to cells and mice infected with Listeria monocytogenes. In this study, we investigate the impact of IFN-I on the activity of listeriolysin O (LLO), a pore-forming toxin and virulence protein released by L. monocytogenes. Treatment of macrophages with IFN-β increased the ability of sublytic LLO concentrations to cause transient permeability of the plasma membrane. At higher LLO concentrations, IFN-β enhanced the complete breakdown of membrane integrity and cell death. This activity of IFN-β required Stat1. Perturbation of the plasma membrane by LLO resulted in activation of the p38MAPK pathway. IFN-β pretreatment enhanced LLO-mediated signaling through this pathway, consistent with its ability to increase membrane damage. p38MAPK activation in response to LLO was independent of TLR4, a putative LLO receptor, and inhibition of p38MAPK neither enhanced nor prevented LLO-induced death. IFN-β caused cells to express increased amounts of caspase 1 and to produce a detectable caspase 1 cleavage product after LLO treatment. Contrasting recent reports with another pore-forming toxin, this pathway did not aid cell survival as caspase1-deficient cells were equally sensitive to lysis by LLO. Key lipogenesis enzymes were suppressed in IFN-β-treated cells, which may exacerbate the membrane damage caused by LLO.
Mannose-Binding Lectin (MBL) Facilitates Opsonophagocytosis of Yeasts but Not of Bacteria despite MBL Binding
Authors: Brouwer Nannette , Dolman Koert M. , van Houdt Michel , Sta Marleen , Roos Dirk , Kuijpers Taco W. 
Published: April 2014

AbstractMannose-binding lectin (MBL) is a serum protein of the innate immune system. After binding to a microorganism, MBL in complex with MBL-associated serine proteases activates the complement system, resulting in cleavage of complement factor C3. Cleaved C3 on the surface of the microorganism mediates opsonization for clearance, but the impact of MBL on subsequent phagocytosis has not been widely studied. We investigated the role of MBL in complement activation and phagocytosis of various bacteria and yeast species by flow cytometry. We measured both the C3 deposition during serum opsonization of fluorescent-labeled microorganisms as well as subsequent uptake of these microorganisms by human neutrophils. In MBL-deficient sera, a consistently decreased C3 deposition on both zymosan and Candida albicans was found and a reduced phagocytosis by neutrophils that was restored by exogenous MBL. This indicates that the lectin pathway of complement activation is important for the opsonophagocytosis of yeasts. In contrast, the C1q-dependent classical pathway dominated in the opsonization and phagocytosis of Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli, whereas no effect of MBL was found. Both the lectin and the classical pathway of complement activation were highly amplified by the alternative route for opsonophagocytosis by neutrophils of yeast as well as microbial species. In summary, our data demonstrate that yeast species are preferentially opsonized and subsequently phagocytosed via activation of the lectin pathway of complement, whereas the uptake of bacterial strains was found to be largely MBL independent.
Anthrax Lethal Toxin Increases Superoxide Production in Murine Neutrophils via Differential Effects on MAPK Signaling Pathways
Authors: Xu Lixin , Fang Hui , Frucht David M. 
Published: April 2014

Abstract
The combination of lethal factor and its receptor-binding partner, protective Ag, is termed lethal toxin (LT) and has critical pathogenic activity during infection with Bacillus anthracis. We herein report that anthrax LT binds and enters murine neutrophils, leading to the cleavage of mitogen-activated protein kinase kinase/MEK/MAPKK 1–4 and 6, but not mitogen-activated protein kinase kinase 5 and 7. Anthrax LT treatment of neutrophils disrupts signaling to downstream MAPK targets in response to TLR stimulation. Following anthrax LT treatment, ERK family and p38 phosphorylation are nearly completely blocked, but signaling to JNK family members persists in vitro and ex vivo. In contrast to previous reports involving human neutrophils, anthrax LT treatment of murine neutrophils increases their production of superoxide in response to PMA or TLR stimulation in vitro or ex vivo. Although this enhanced superoxide production correlates with effects due to the LT-induced blockade of ERK signaling, it requires JNK signaling that remains largely intact despite the activity of anthrax LT. These findings reveal a previously unrecognized mechanism through which anthrax LT supports a critical proinflammatory response of murine neutrophils.
Endogenous IFN-γ Production Is Induced and Required for Protective Immunity against Pulmonary Chlamydial Infection in Neonatal Mice
Authors: Jupelli Madhulika , Guentzel M. Neal , Meier Patricia A. , Zhong Guangming , Murthy Ashlesh K. , Arulanandam Bernard P. 
Published: April 2014

AbstractChlamydia trachomatis infection in neonates, not adults, has been associated with the development of chronic respiratory sequelae. Adult chlamydial infections induce Th1-type responses that subsequently clear the infection, whereas the neonatal immune milieu in general has been reported to be biased toward Th2-type responses. We examined the protective immune responses against intranasal Chlamydia muridarum challenge in 1-day-old C57BL/6 and BALB/c mice. Infected C57BL/6 pups displayed earlier chlamydial clearance (day 14) compared with BALB/c pups (day 21). However, challenged C57BL/6 pups exhibited prolonged deficits in body weight gain (days 12–30) compared with BALB/c pups (days 9–12), which correlated with continual pulmonary cellular infiltration. Both strains exhibited a robust Th1-type response, including elevated titers of serum antichlamydial IgG2a and IgG2b, not IgG1, and elevated levels of splenic C. muridarum-specific IFN-γ, not IL-4, production. Additionally, elevated IFN-γ, not IL-4 expression, was observed locally in the infected lungs of both mouse strains. The immune responses in C57BL/6 pups were significantly greater compared with BALB/c pups after chlamydial challenge. Importantly, infected mice deficient in IFN-γ or IFN-γ receptor demonstrated enhanced chlamydial dissemination, and 100% of animals died by 2 wk postchallenge. Collectively, these results indicate that neonatal pulmonary chlamydial infection induces a robust Th1-type response, with elevated pulmonary IFN-γ production, and that endogenous IFN-γ is important in protection against this infection. The enhanced IFN-γ induction in the immature neonatal lung also may be relevant to the development of respiratory sequelae in adult life.
ERK5/BMK1 Is Indispensable for Optimal Colony-Stimulating Factor 1 (CSF-1)-Induced Proliferation in Macrophages in a Src-Dependent Fashion
Authors: Rovida Elisabetta , Spinelli Elena , Sdelci Sara , Barbetti Valentina , Morandi Andrea , Giuntoli Serena , Dello Sbarba Persio 
Published: April 2014

Abstract
CSF-1, by binding to its high-affinity receptor CSF-1R, sustains the survival and proliferation of monocyte/macrophages, which are central cells of innate immunity and inflammation. The MAPK ERK5 (also known as big MAPK-1, BMK1, or MAPK7) is a 98-kDa molecule sharing high homology with ERK1/2. ERK5 is activated by oxidative stress or growth factor stimulation. This study was undertaken to characterize ERK5 involvement in macrophage signaling that is elicited by CSF-1. Exposure to the CSF-1 of primary human macrophages or murine macrophage cell lines, as well as murine fibroblasts expressing ectopic CSF-1R, resulted in a rapid and sustained increase of ERK5 phosphorylation on activation-specific residues. In the BAC1.2F5 macrophage cell line, ERK5 was also activated by another mitogen, GM-CSF, while macrophage activators such as LPS or IFN-γ and a number of nonproliferative cytokines failed. Src family kinases were found to link the activation of CSF-1R to that of ERK5, whereas protein kinase C or the serine phosphatases PP1 and PP2A seem not to be involved in the process. Treatment of macrophages with ERK5-specific small interfering RNA markedly reduced CSF-1-induced DNA synthesis and total c-Jun phosphorylation and expression, while increasing the expression of the cyclin-dependent kinase inhibitor p27. Following CSF-1 treatment, the active form of ERK5 rapidly translocated from cytosol to nucleus. Taken together, the results reported in this study show that ERK5 is indispensable for optimal CSF-1-induced proliferation and indicate a novel target for its control.