bluuebunny/crossref_metadata_2025 huggingface dataset:
Cytokine-Mediated Disruption of Lymphocyte Trafficking, Hemopoiesis, and Induction of Lymphopenia, Anemia, and Thrombocytopenia in Anti-CD137-Treated Mice
Authors: Niu Liguo , Strahotin Simona , Hewes Becker , Zhang Benyue , Zhang Yuanyuan , Archer David , Spencer Trent , Dillehay Dirck , Kwon Byoung , Chen Lieping , Vella Anthony T. , Mittler Robert S.
Published: April 2014

CD137-mediated signals costimulate T cells and protect them from activation-induced apoptosis; they induce curative antitumor immunity and enhance antiviral immune responses in mice. In contrast, anti-CD137 agonistic mAbs can suppress T-dependent humoral immunity and reverse the course of established autoimmune disease. These results have provided a rationale for assessing the therapeutic potential of CD137 ligands in human clinical trials. In this study, we report that a single 200-μg injection of anti-CD137 given to otherwise naive BALB/c or C57BL/6 mice led to the development of a series of immunological anomalies. These included splenomegaly, lymphadenopathy, hepatomegaly, multifocal hepatitis, anemia, altered trafficking of B cells and CD8 T cells, loss of NK cells, and a 10-fold increase in bone marrow (BM) cells bearing the phenotype of hemopoietic stem cells. These events were dependent on CD8 T cells, TNF-α, IFN-γ, and type I IFNs. BM cells up-regulated Fas, and there was a significant increase in the number of CD8+ T cells that correlated with a loss of CD19+ and Ab-secreting cells in the BM. TCR Vαβ usage was random and polyclonal among liver-infiltrating CD8 T cells, and multifocal CD8+ T cell infiltrates were resolved upon termination of anti-CD137 treatment. Anti-CD137-treated mice developed lymphopenia, thrombocytopenia, and anemia, and had lowered levels of hemoglobin and increased numbers of reticulocytes.
Non-Cell Autonomous Expression of TNF-α-Converting Enzyme ADAM17 Is Required for Normal Lymphocyte Development
Authors: Li Nianyu , Boyd Kelli , Dempsey Peter J. , Vignali Dario A. A.
Published: April 2014

TNF-α converting enzyme (TACE; ADAM17), a member of the ADAM (a disintegrin and metalloprotease) family of metalloproteases, has been shown to cleave a wide variety of cell surface proteins of immunological importance. Due to the broad expression of TACE and the early postnatal lethality of TACE-deficient mice, it has been difficult to assess the role of TACE in lymphocyte development. Indeed, it is not known whether hemopoietic and/or nonhemopoietic expression of TACE is required for normal lymphocyte development. In the current study, we analyzed the lymphoid system of taceΔZn/ΔZn mice and taceΔZn/ΔZn bone marrow RAG1−/− recipients. Our results clearly show that nonlymphocyte expression of TACE is required for normal lymphocyte development and lymphoid organ structure. Lack of TACE function resulted in a partial block in T cell development at the double-negative 4:double-positive transition in the thymus, a loss of B cell development/maturation in the spleen, and a lack of B cell follicle and germinal center formation in the spleen. Thus, TACE serves as a lymphocyte extrinsic factor that is essential for normal T development and peripheral B cell maturation.
Regulation of Carcinogenesis by IL-5 and CCL11: A Potential Role for Eosinophils in Tumor Immune Surveillance
Authors: Simson Ljubov , Ellyard Julia I. , Dent Lindsay A. , Matthaei Klaus I. , Rothenberg Marc E. , Foster Paul S. , Smyth Mark J. , Parish Christopher R.
Published: April 2014

The role of the immune system in the surveillance of transformed cells has seen a resurgence of interest in the last 10 years, with a substantial body of data in mice and humans supporting a role for the immune system in host protection from tumor development and in shaping tumor immunogenicity. A number of earlier studies have demonstrated that eosinophils, when recruited into tumors, can very effectively eradicate transplantable tumors. In this study, we investigated whether eosinophils also play a role in tumor immune surveillance by determining the incidence of methylcholanthrene (MCA)-induced fibrosarcomas in IL-5 transgenic mice that have greatly enhanced levels of circulating eosinophils, CCL11 (eotaxin-1)-deficient mice that lack a key chemokine that recruits eosinophils into tissues, and the eosinophil-deficient mouse strains, IL-5/CCL11−/− and ΔdblGATA. It was found that MCA-induced tumor incidence and growth were significantly attenuated in IL-5 transgenic mice of both the BALB/c and C57BL/6 backgrounds. Histological examination revealed that the protective effect of IL-5 was associated with massively enhanced numbers of eosinophils within and surrounding tumors. Conversely, there was a higher tumor incidence in CCL11−/− BALB/c mice, which was associated with a reduced eosinophil influx into tumors. This correlation was confirmed in the eosinophil-deficient IL-5/CCL11−/− and ΔdblGATA mouse strains, where tumor incidence was greatly increased in the total absence of eosinophils. In addition, subsequent in vitro studies found that eosinophils could directly kill MCA-induced fibrosarcoma cells. Collectively, our data support a potential role for the eosinophil as an effector cell in tumor immune surveillance.
Limited Peripheral T Cell Anergy Predisposes to Retinal Autoimmunity
Authors: Lambe Teresa , Leung Janson C. H. , Ferry Helen , Bouriez-Jones Tiphaine , Makinen Kimmo , Crockford Tanya L. , Jiang Hui R. , Nickerson John M. , Peltonen Leena , Forrester John V. , Cornall Richard J.
Published: April 2014

Autoimmune uveoretinitis accounts for at least 10% of worldwide blindness, yet it is unclear why tolerance to retinal Ags is so fragile and, particularly, to what extent this might be due to defects in peripheral tolerance. To address this issue, we generated double-transgenic mice expressing hen egg lysozyme, under the retinal interphotoreceptor retinoid-binding promoter, and a hen egg lysozyme-specific CD4+ TCR transgene. In this manner, we have tracked autoreactive CD4+ T cells from their development in the thymus to their involvement in uveoretinitis and compared tolerogenic mechanisms induced in a variety of organs to the same self-Ag. Our findings show that central tolerance to retinal and pancreatic Ags is qualitatively similar and equally dependent on the transcriptional regulator protein AIRE. However, the lack of Ag presentation in the eye-draining lymph nodes results in a failure to induce high levels of T cell anergy. Under these circumstances, despite considerable central deletion, low levels of retinal-specific autoreactive CD4+ T cells can induce severe autoimmune disease. The relative lack of anergy induction by retinal Ags, in contrast to the same Ag in other organs, helps to explain the unique susceptibility of the eye to spontaneous and experimentally induced autoimmune disease.
Human TIM-1 Associates with the TCR Complex and Up-Regulates T Cell Activation Signals
Authors: Binné Lauri L. , Scott Martin L. , Rennert Paul D.
Published: April 2014

The T cell, Ig domain, and mucin domain-1 (TIM-1) gene is associated with Th2 T cell responses and human atopic diseases. The mechanism by which TIM-1 influences T cell responses remains unknown. We demonstrate that TIM-1 is recruited to the TCR-signaling complex via association with CD3. TIM-1 up-regulates TCR-associated signaling events, including phosphorylation of Zap70 and IL-2-inducible T cell kinase. This activity requires TIM-1 tyrosine phosphorylation. TIM-1 expression induces formation of a novel complex that includes PI3K and ITK. Finally, the consequences of TIM-1 activation include increased expression of effector cytokines. These results demonstrate that TIM-1 is a critical component of the human T cell response and provide a mechanistic hypothesis for the role of TIM-1 in disease.
Peroxisome Proliferator-Activated Receptor-α Activation Inhibits Langerhans Cell Function
Authors: Dubrac Sandrine , Stoitzner Patrizia , Pirkebner Daniela , Elentner Andreas , Schoonjans Kristina , Auwerx Johan , Saeland Sem , Hengster Paul , Fritsch Peter , Romani Nikolaus , Schmuth Matthias
Published: April 2014

Epidermal Langerhans cells (LC) play a pivotal role in initiating and maintaining primary immune responses in the skin. In the present study, we asked whether peroxisome proliferator-activated receptor-α (PPARα) activation modulates LC function. Our results show that PPARα is expressed in immature LC and is down-regulated in mature LC suggesting that an early decrease of PPARα expression in LC may allow them to mature after contact with an Ag. We further show that pharmacologic PPARα activation inhibits LC maturation, migratory capacity, cytokine expression, and the ability to drive T cell proliferation. Moreover, PPARα activation inhibits NF-κB but not stress-activated protein kinase/JNK, p38MAPK, and ERK1/2. In conclusion, PPARα activation by endogenous ligands may provide a molecular signal that allows LC to remain in an immature state within the epidermis for extended periods of time despite minor environmental stimuli.
Bcl10 Controls TCR- and FcγR-Induced Actin Polymerization
Authors: Rueda Daniel , Gaide Olivier , Ho Liza , Lewkowicz Elodie , Niedergang Florence , Hailfinger Stephan , Rebeaud Fabien , Guzzardi Montserrat , Conne Béatrice , Thelen Marcus , Delon Jérôme , Ferch Uta , Mak Tak W. , Ruland Jürgen , Schwaller Jürg , Thome Margot
Published: April 2014

Bcl10 plays an essential role in the adaptive immune response, because Bcl10-deficient lymphocytes show impaired Ag receptor-induced NF-κB activation and cytokine production. Bcl10 is a phosphoprotein, but the physiological relevance of this posttranslational modification remains poorly defined. In this study, we report that Bcl10 is rapidly phosphorylated upon activation of human T cells by PMA/ionomycin- or anti-CD3 treatment, and identify Ser138 as a key residue necessary for Bcl10 phosphorylation. We also show that a phosphorylation-deficient Ser138/Ala mutant specifically inhibits TCR-induced actin polymerization yet does not affect NF-κB activation. Moreover, silencing of Bcl10, but not of caspase recruitment domain-containing MAGUK protein-1 (Carma1) induces a clear defect in TCR-induced F-actin formation, cell spreading, and conjugate formation. Remarkably, Bcl10 silencing also impairs FcγR-induced actin polymerization and phagocytosis in human monocytes. These results point to a key role of Bcl10 in F-actin-dependent immune responses of T cells and monocytes/macrophages.
The Bxs6 Locus of BXSB Mice Is Sufficient for High-Level Expression of gp70 and the Production of gp70 Immune Complexes
Authors: Rankin Joanna , Boyle Joseph J. , Rose S. Jane , Gabriel Luisa , Lewis Margarita , Thiruudaian Vasuky , Rogers Nicola J. , Izui Shozo , Morley Bernard J.
Published: April 2014

High levels of the retroviral envelope protein gp70 and gp70 immune complexes have been linked to a single locus on chromosome 13 (Bxs6) in the BXSB model, to which linkage of nephritis was also seen. Congenic lines containing the BXSB Bxs6 interval on a non-autoimmune C57BL/10 background were bred in the presence or absence of the BXSB Y chromosome autoimmune accelerator gene (Yaa), which accelerates disease in male mice. In these mice, we have shown that Bxs6 is sufficient to cause high-level expression of gp70 and the production of gp70 autoantibodies, independently of Yaa, with gp70 immune complex levels enhanced by Yaa. In the presence of Yaa, Bxs6 also causes mild nephritis, and interestingly the sporadic production of high levels of anti-DNA Abs in some mice. Fine mapping using rare recombinant mice suggested that Bxs6 lies between 59.7 and 74.8 megabases (Mb), although the interval of 0.6 Mb between 73.6 and 78.6 Mb on chromosome 13 cannot be excluded in this study.
Human KIR2DL5 Is an Inhibitory Receptor Expressed on the Surface of NK and T Lymphocyte Subsets
Authors: Estefanía Ernesto , Flores Raquel , Gómez-Lozano Natalia , Aguilar Helena , López-Botet Miguel , Vilches Carlos
Published: April 2014

Human NK cells, by means of a repertoire of clonally distributed killer cell Ig-like receptors (KIR), survey the expression of individual self HLA class I molecules, which is often altered in infections and tumors. KIR2DL5 (CD158f) is the last identified KIR gene and, with KIR2DL4, constitutes a structurally divergent lineage conserved in different primate species. Research on KIR2DL5 has thus far been limited to its genetic aspects due to a lack of reagents to detect its product. We report here the identification and characterization of the receptor encoded by KIR2DL5 using a newly generated specific mAb that recognizes its most commonly expressed allele, KIR2DL5A*001. KIR2DL5 displays a variegated distribution on the surface of CD56dim NK cells. This contrasts with the expression pattern of its structural homolog KIR2DL4 (ubiquitous transcription, surface expression restricted to CD56bright NK cells) and resembles the profile of KIR recognizing classical HLA class I molecules. Like other MHC class I receptors, KIR2DL5 is also found in a variable proportion of T lymphocytes. KIR2DL5 is detected on the cell surface as a monomer of ∼60 kDa that, upon tyrosine phosphorylation, recruits the Src homology region 2-containing protein tyrosine phosphatase-2 and, to a lesser extent, Src homology region 2-containing protein tyrosine phosphatase-1. Ab-mediated cross-linking of KIR2DL5 inhibits NK cell cytotoxicity against murine FcR+ P815 cells. KIR2DL5 is thus an inhibitory receptor gathering a combination of genetic, structural, and functional features unique among KIR, which suggests that KIR2DL5 plays a specialized role in innate immunity.
Peptide Mimics of the Group B Meningococcal Capsule Induce Bactericidal and Protective Antibodies after Immunization
Authors: Lo Passo Carla , Romeo Angela , Pernice Ida , Donato Paolo , Midiri Angelina , Mancuso Giuseppe , Arigò Milena , Biondo Carmelo , Galbo Roberta , Papasergi Salvatore , Felici Franco , Teti Giuseppe , Beninati Concetta
Published: April 2014

Neisseria meningitidis serogroup B (MenB) is a leading cause of sepsis and meningitis in children. No vaccine is available for the prevention of these infections because the group B capsular polysaccharide (CP) (MenB CP) is unable to stimulate an immune response, due to its similarity with human polysialic acid. Because the MenB CP bears both human cross-reactive and non-cross-reactive determinants, we developed immunogenic peptide mimics of the latter epitopes. Peptides were selected from phage display libraries for their ability to bind to a protective anti-MenB CP mAb. One of these peptides (designated 9M) induced marked elevations in serum bactericidal activity, but not polysialic acid cross-reacting Abs, after gene priming followed by carrier-conjugate boosting. Moreover, the occurrence of bacteremia was prevented in infant rats by administration of immune sera before MenB challenge. 9M is a promising lead candidate for the development of an effective and affordable anti-MenB vaccine.
TLR Ligand-Dependent Activation of Naive CD4 T Cells by Plasmacytoid Dendritic Cells Is Impaired in Hepatitis C Virus Infection
Authors: Yonkers Nicole L. , Rodriguez Benigno , Milkovich Kimberly A. , Asaad Robert , Lederman Michael M. , Heeger Peter S. , Anthony Donald D.
Published: April 2014

Chronic hepatitis C virus (HCV) infection is characterized by diminished numbers and function of HCV-reactive T cells and impaired responses to immunization. Because host response to viral infection likely involves TLR signaling, we examined whether chronic HCV infection impairs APC response to TLR ligand and contributes to the origin of dysfunctional T cells. Freshly purified myeloid dendritic cells (MDC) and plasmacytoid DC (PDC) obtained from subjects with chronic HCV infection and healthy controls were exposed to TLR ligands (poly(I:C), R-848, or CpG), in the presence or absence of cytokine (TNF-α or IL-3), and examined for indices of maturation and for their ability to activate allogeneic naive CD4 T cells to proliferate and secrete IFN-γ. TLR ligand was observed to enhance both MDC and PDC activation of naive CD4 T cells. Although there was increased CD83 and CD86 expression on MDC from HCV-infected persons, the ability of MDC to activate naive CD4 T cells in the presence or absence of poly(I:C) or TNF-α did not differ between HCV-infected and healthy control subjects. In contrast, PDC from HCV-infected persons had reduced activation marker (HLA-DR) and cytokine (IFN-α) expression upon R-848 stimulation, and these were associated with impaired activation of naive CD4 T cells. These data indicate that an impaired PDC responsiveness to TLR ligation may play an important role in the fundamental and unexplained failure to induce new T cell responses to HCV Ags and to other new Ags as a consequence of HCV infection.
Francisella tularensis Induces IL-23 Production in Human Monocytes
Authors: Butchar Jonathan P. , Rajaram Murugesan V. S. , Ganesan Latha P. , Parsa Kishore V. L. , Clay Corey D. , Schlesinger Larry S. , Tridandapani Susheela
Published: April 2014

Francisella tularensis, the causative agent of tularemia, is phagocytosed by immune cells such as monocytes and macrophages. Instead of being destroyed in the phagolysosome, the bacterium escapes the phagosome and replicates within the host cytosol. Recent studies indicate that phagosomal escape may have a major impact on the nature of the inflammatory cytokine response to infection. To better understand the host cell response to Francisella infection, we exposed human peripheral blood monocytes to Francisella novicida and analyzed transcriptional changes using high-density oligonucleotide microarrays. Results showed a nearly 300-fold up-regulation of transcripts for the p19 subunit of IL-23, and a nearly 18-fold up-regulation for the p40 subunit of IL-12. IL-23 is formed by the heterodimerization of p19 and p40, and is an important cytokine of the innate immune response. Up-regulation of p19 and p40 was confirmed at the protein level by Western blotting and ELISA analyses, and was found to be largely dependent on PI3K and NF-κB activity. Studies using medium from infected monocytes with or without a p19 blocking Ab showed that the secreted IL-23 induced IFN-γ production from NK cells, suggesting a potential biologically important role for IL-23 in host defense. Finally, infection of human monocytes by the highly virulent Francisella SCHU S4 strain likewise led to IL-23 production, suggesting that the IL-23 response may be relevant during tularemia.
The Human Cytomegalovirus MHC Class I Homolog UL18 Inhibits LIR-1+ but Activates LIR-1− NK Cells
Authors: Prod’homme Virginie , Griffin Cora , Aicheler Rebecca J. , Wang Eddie C. Y. , McSharry Brian P. , Rickards Carole R. , Stanton Richard J. , Borysiewicz Leszek K. , López-Botet Miguel , Wilkinson Gavin W. G. , Tomasec Peter
Published: April 2014

The inhibitory leukocyte Ig-like receptor 1 (LIR-1, also known as ILT2, CD85j, or LILRB1) was identified by its high affinity for the human CMV (HCMV) MHC class I homolog gpUL18. The role of this LIR-1-gpUL18 interaction in modulating NK recognition during HCMV infection has previously not been clearly defined. In this study, LIR-1+ NKL cell-mediated cytotoxicity was shown to be inhibited by transduction of targets with a replication-deficient adenovirus vector encoding UL18 (RAd-UL18). Fibroblasts infected with an HCMV UL18 mutant (ΔUL18) also exhibited enhanced susceptibility to NKL killing relative to cells infected with the parental virus. In additional cytolysis assays, UL18-mediated protection was also evident in the context of adenovirus vector transduction and HCMV infection of autologous fibroblast targets using IFN-α-activated NK bulk cultures derived from a donor with a high frequency of LIR-1+ NK cells. A single LIR-1high NK clone derived from this donor was inhibited by UL18, while 3 of 24 clones were activated. CD107 mobilization assays revealed that LIR-1+ NK cells were consistently inhibited by UL18 in all tested donors, but this effect was often masked in the global response by UL18-mediated activation of a subset of LIR-1− NK cells. Although Ab-blocking experiments support UL18 inhibition being induced by a direct interaction with LIR-1, the UL18-mediated activation is LIR-1 independent.
IL-12 and Type-I IFN Synergize for IFN-γ Production by CD4 T Cells, Whereas Neither Are Required for IFN-γ Production by CD8 T Cells afterListeria monocytogenesInfection
Authors: Way Sing Sing , Havenar-Daughton Colin , Kolumam Ganesh A. , Orgun Nural N. , Murali-Krishna Kaja
Published: April 2014

Differentiation of Ag-specific T cells into IFN-γ producers is essential for protective immunity to intracellular pathogens. In addition to stimulation through the TCR and costimulatory molecules, IFN-γ production is thought to require other inflammatory cytokines. Two such inflammatory cytokines are IL-12 and type I IFN (IFN-I); both can play a role in priming naive T cells to produce IFN-γ in vitro. However, their role in priming Ag-specific T cells for IFN-γ production during experimental infection in vivo is less clear. In this study, we examine the requirements for IL-12 and IFN-I, either individually or in combination, for priming Ag-specific T cell IFN-γ production after Listeria monocytogenes (Lm) infection. Surprisingly, neither individual nor combined defects in IL-12 or IFN-I signaling altered IFN-γ production by Ag-specific CD8 T cells after Lm infection. In contrast, individual defects in either IL-12 or IFN-I signaling conferred partial (∼50%) reductions, whereas combined deficiency in both IL-12 and IFN-I signaling conferred more dramatic (75–95%) reductions in IFN-γ production by Ag-specific CD4 T cells. The additive effects of IL-12 and IFN-I signaling on IFN-γ production by CD4 T cells were further demonstrated by adoptive transfer of transgenic IFN-IR+/+ and IFN-IR−/− CD4 T cells into normal and IL-12-deficient mice, and infection with rLm. These results demonstrate an important dichotomy between the signals required for priming IFN-γ production by CD4 and CD8 T cells in response to bacterial infection.
Evidence for Evolving Toll-IL-1 Receptor-Containing Adaptor Molecule Function in Vertebrates
Authors: Sullivan Con , Postlethwait John H. , Lage Christopher R. , Millard Paul J. , Kim Carol H.
Published: April 2014

In mammals, Toll-IL-1R-containing adaptor molecule 1 (TICAM1)-dependent TLR pathways induce NF-κB and IFN-β responses. TICAM1 activates NF-κB through two different pathways involving its interactions with TNFR-associated factor 6 and receptor-interacting protein 1. It also activates IFN regulatory factor 3/7 through its interaction with TANK-binding kinase-1, leading to the robust up-regulation of IFN-β. In this study, we describe the role of zebrafish (Danio rerio) TICAM1 in activating NF-κB and zebrafish type I IFN. Zebrafish IFN is unique in that it cannot be categorized as being α- or β-like. Through comprehensive sequence, phylogenetic, and syntenic analyses, we fully describe the identification of a zebrafish TICAM1 ortholog. Zebrafish TICAM1 exhibits sequence divergence from its mammalian orthologs and our data demonstrate that these sequence differences have functional consequences. Zebrafish TICAM1 activates zebrafish IFN; however, it does so in an apparently IFN regulatory factor 3/7-independent manner. Furthermore, zebrafish TICAM1 does not interact with zebrafish TNFR-associated factor 6, thus NF-κB activation is dependent upon its interaction with receptor-interacting protein 1. Comparative genome analysis suggests that TICAM1 and TICAM2 evolved from a common vertebrate TICAM ancestor following a gene duplication event and that TICAM2 was lost in teleosts following the divergence of the rayfin and lobefin fishes 450 million years ago. These studies provide evidence, for the first time, of the evolving function of a vertebrate TLR pathway.
MyD88-Dependent Signals Are Essential for the Host Immune Response in Experimental Brain Abscess
Authors: Kielian Tammy , Phulwani Nirmal K. , Esen Nilufer , Syed Mohsin Md. , Haney Anessa C. , McCastlain Kelly , Johnson Jennifer
Published: April 2014

Brain abscesses form in response to a parenchymal infection by pyogenic bacteria, with Staphylococcus aureus representing a common etiologic agent of human disease. Numerous receptors that participate in immune responses to bacteria, including the majority of TLRs, the IL-1R, and the IL-18R, use a common adaptor molecule, MyD88, for transducing activation signals leading to proinflammatory mediator expression and immune effector functions. To delineate the importance of MyD88-dependent signals in brain abscesses, we compared disease pathogenesis using MyD88 knockout (KO) and wild-type (WT) mice. Mortality rates were significantly higher in MyD88 KO mice, which correlated with a significant reduction in the expression of several proinflammatory mediators, including but not limited to IL-1β, TNF-α, and MIP-2/CXCL2. These changes were associated with a significant reduction in neutrophil and macrophage recruitment into brain abscesses of MyD88 KO animals. In addition, microglia, macrophages, and neutrophils isolated from the brain abscesses of MyD88 KO mice produced significantly less TNF-α, IL-6, MIP-1α/CCL3, and IFN-γ-induced protein 10/CXCL10 compared with WT cells. The lack of MyD88-dependent signals had a dramatic effect on the extent of tissue injury, with significantly larger brain abscesses typified by exaggerated edema and necrosis in MyD88 KO animals. Interestingly, despite these striking changes in MyD88 KO mice, bacterial burdens did not significantly differ between the two strains at the early time points examined. Collectively, these findings indicate that MyD88 plays an essential role in establishing a protective CNS host response during the early stages of brain abscess development, whereas MyD88-independent pathway(s) are responsible for pathogen containment.
Active Suppression of the Pulmonary Immune Response by Francisella tularensis Schu4
Authors: Bosio Catharine M. , Bielefeldt-Ohmann Helle , Belisle John T.
Published: April 2014

Francisella tularensis is an obligate, intracellular bacterium that causes acute, lethal disease following inhalation. As an intracellular pathogen F. tularensis must invade cells, replicate, and disseminate while evading host immune responses. The mechanisms by which virulent type A strains of Francisella tularensis accomplish this evasion are not understood. Francisella tularensis has been shown to target multiple cell types in the lung following aerosol infection, including dendritic cells (DC) and macrophages. We demonstrate here that one mechanism used by a virulent type A strain of F. tularensis (Schu4) to evade early detection is by the induction of overwhelming immunosuppression at the site of infection, the lung. Following infection and replication in multiple pulmonary cell types, Schu4 failed to induce the production of proinflammatory cytokines or increase the expression of MHCII or CD86 on the surface of resident DC within the first few days of disease. However, Schu4 did induce early and transient production of TGF-β, a potent immunosuppressive cytokine. The absence of DC activation following infection could not be attributed to the apoptosis of pulmonary cells, because there were minimal differences in either annexin or cleaved caspase-3 staining in infected mice compared with that in uninfected controls. Rather, we demonstrate that Schu4 actively suppressed in vivo responses to secondary stimuli (LPS), e.g., failure to recruit granulocytes/monocytes and stimulate resident DC. Thus, unlike attenuated strains of F. tularensis, Schu4 induced broad immunosuppression within the first few days after aerosol infection. This difference may explain the increased virulence of type A strains compared with their more attenuated counterparts.
Recognition of Double-Stranded RNA by TLR3 Induces Severe Small Intestinal Injury in Mice
Authors: Zhou Rongbin , Wei Haiming , Sun Rui , Tian Zhigang
Published: April 2014

The role of TLRs on intestinal epithelial cells (IECs) is controversial, and the mechanisms by which TLRs influence mucosal homeostasis are obscure. In this study, we report that genomic dsRNA from rotavirus, and its synthetic analog polyinosinic-polycytidylic acid (poly(I:C)), induce severe mucosal injury in the small intestine. Upon engaging TLR3 on IECs, dsRNA triggers IECs to secrete IL-15, which functions to increase the percentage of CD3+NK1.1+ intestinal intraepithelial lymphocytes (IELs) and enhances the cytotoxicity of IELs. Moreover, The CD3+NK1.1+ IELs are proved as CD8αα+ IELs. These results provide direct evidence that abnormal TLR3 signaling contributes to breaking down mucosal homeostasis and the first evidence of pathogenic effects mediated by CD8αα+ IELs. The data also suggest that genomic dsRNA may be involved in the pathogenesis of acute rotavirus gastroenteritis.
Infection with a Helminth Parasite Prevents Experimental Colitis via a Macrophage-Mediated Mechanism
Authors: Smith Philip , Mangan Niamh E. , Walsh Caitriona M. , Fallon Rosie E. , McKenzie Andrew N. J. , van Rooijen Nico , Fallon Padraic G.
Published: April 2014

The propensity of a range of parasitic helminths to stimulate a Th2 or regulatory cell-biased response has been proposed to reduce the severity of experimental inflammatory bowel disease. We examined whether infection with Schistosoma mansoni, a trematode parasite, altered the susceptibility of mice to colitis induced by dextran sodium sulfate (DSS). Mice infected with schistosome worms were refractory to DSS-induced colitis. Egg-laying schistosome infections or injection of eggs did not render mice resistant to colitis induced by DSS. Schistosome worm infections prevent colitis by a novel mechanism dependent on macrophages, and not by simple modulation of Th2 responses, or via induction of regulatory CD4+ or CD25+ cells, IL-10, or TGF-β. Infected mice had marked infiltration of macrophages (F4/80+CD11b+CD11c−) into the colon lamina propria and protection from DSS-induced colitis was shown to be macrophage dependent. Resistance from colitis was not due to alternatively activated macrophages. Transfer of colon lamina propria F4/80+ macrophages isolated from worm-infected mice induced significant protection from colitis in recipient mice treated with DSS. Therefore, we propose a new mechanism whereby a parasitic worm suppresses DSS-induced colitis via a novel colon-infiltrating macrophage population.
Histamine Release from the Basophils of Control and Asthmatic Subjects and a Comparison of Gene Expression between “Releaser” and “Nonreleaser” Basophils
Authors: Youssef Lama A. , Schuyler Mark , Gilmartin Laura , Pickett Gavin , Bard Julie D. J. , Tarleton Christy A. , Archibeque Tereassa , Qualls Clifford , Wilson Bridget S. , Oliver Janet M.
Published: April 2014

Most human blood basophils respond to FcεRI cross-linking by releasing histamine and other inflammatory mediators. Basophils that do not degranulate after anti-IgE challenge, known as “nonreleaser” basophils, characteristically have no or barely detectable levels of the Syk tyrosine kinase. The true incidence of the nonreleaser phenotype, its relationship (if any) to allergic asthma, and its molecular mechanism are not well understood. In this study, we report statistical analyses of degranulation assays performed in 68 control and 61 asthmatic subjects that establish higher basal and anti-IgE-stimulated basophil degranulation among the asthmatics. Remarkably, 28% of the control group and 13% of the asthmatic group were nonreleasers for all or part of our 4-year long study and cycling between the releaser and nonreleaser phenotypes occurred at least once in blood basophils from 8 (of 8) asthmatic and 16 (of 23) control donors. Microarray analysis showed that basal gene expression was generally lower in nonreleaser than releaser basophils. In releaser cells, FcεRI cross-linking up-regulated >200 genes, including genes encoding receptors (the FcεRI α and β subunits, the histamine 4 receptor, the chemokine (C-C motif) receptor 1), signaling proteins (Lyn), chemokines (IL-8, RANTES, MIP-1α, and MIP-1β) and transcription factors (early growth response-1, early growth response-3, and AP-1). FcεRI cross-linking induced fewer, and quite distinct, transcriptional responses in nonreleaser cells. We conclude that “nonreleaser” and “cycler” basophils represent a distinct and reversible natural phenotype. Although histamine is more readily released from basophils isolated from asthmatics than controls, the presence of nonreleaser basophils does not rule out the diagnosis of asthma.
Loss of SLP-76 Expression within Myeloid Cells Confers Resistance to Neutrophil-Mediated Tissue Damage while Maintaining Effective Bacterial Killing
Authors: Clemens Regina A. , Lenox Laurie E. , Kambayashi Taku , Bezman Natalie , Maltzman Jonathan S. , Nichols Kim E. , Koretzky Gary A.
Published: April 2014

The Src homology 2 domain-containing leukocyte phosphoprotein of 76 kDa (SLP-76) is an adaptor molecule critical for immunoreceptor and integrin signaling in multiple hemopoietic lineages. We showed previously that SLP-76 is required for neutrophil function in vitro, including integrin-induced adhesion and production of reactive oxygen intermediates, and to a lesser extent, FcγR-induced calcium flux and reactive oxygen intermediate production. It has been difficult to determine whether SLP-76 regulates neutrophil responses in vivo, because Slp-76−/− mice exhibit marked defects in thymocyte and vascular development, as well as platelet and mast cell function. To circumvent these issues, we generated mice with targeted loss of SLP-76 expression within myeloid cells. Neutrophils obtained from these animals failed to respond to integrin activation in vitro, similar to Slp-76−/− cells. Despite these abnormalities, SLP-76-deficient neutrophils migrated normally in vivo in response to Staphylococcus aureus infection and efficiently cleared micro-organisms. Interestingly, SLP-76-deficient neutrophils did not induce a robust inflammatory response in the localized Shwartzman reaction. Collectively, these data suggest that disruption of integrin signaling via loss of SLP-76 expression differentially impairs neutrophil functions in vivo, with preservation of migration and killing of S. aureus but reduction in LPS-induced tissue damage and vascular injury.
TGF-β1-Mediated Control of Central Nervous System Inflammation and Autoimmunity through the Inhibitory Receptor CD26
Authors: Preller Vera , Gerber Annegret , Wrenger Sabine , Togni Mauro , Marguet Didier , Tadje Janine , Lendeckel Uwe , Röcken Christoph , Faust Jürgen , Neubert Klaus , Schraven Burkhart , Martin Roland , Ansorge Siegfried , Brocke Stefan , Reinhold Dirk
Published: April 2014

The T cell marker CD26/dipeptidyl peptidase (DP) IV is associated with an effector phenotype and markedly elevated in the human CNS disorder multiple sclerosis. However, little is known about the in vivo role of CD26/DP IV in health and disease, and the underlying mechanism of its function in CNS inflammation. To directly address the role of CD26/DP IV in vivo, we examined Th1 immune responses and susceptibility to experimental autoimmune encephalomyelitis in CD26−/− mice. We show that gene deletion of CD26 in mice leads to deregulation of Th1 immune responses. Although production of IFN-γ and TNF-α by pathogenic T cells in response to myelin Ag was enhanced in CD26−/− mice, production of the immunosuppressive cytokine TGF-β1 was diminished in vivo and in vitro. In contrast to the reduction in TGF-β1 production, responsiveness to external TGF-β1 was normal in T cells from CD26−/− mice, excluding alterations in TGF-β1 sensitivity as a mechanism causing the loss of immune regulation. Natural ligands of CD26/DP IV induced TGF-β1 production in T cells from wild-type mice. However, natural ligands of CD26/DP IV failed to elicit TGF-β1 production in T cells from CD26−/− mice. The striking functional deregulation of Th1 immunity was also seen in vivo. Thus, clinical experimental autoimmune encephalomyelitis scores were significantly increased in CD26−/− mice immunized with peptide from myelin oligodendrocyte glycoprotein. These results identify CD26/DP IV as a nonredundant inhibitory receptor controlling T cell activation and Th1-mediated autoimmunity, and may have important therapeutic implications for the treatment of autoimmune CNS disease.
T Cell Activation by Antibody-Like Immunoreceptors: The Position of the Binding Epitope within the Target Molecule Determines the Efficiency of Activation of Redirected T Cells
Authors: Hombach Andreas A. , Schildgen Verena , Heuser Claudia , Finnern Ricarda , Gilham David E. , Abken Hinrich
Published: April 2014

Recombinant TCRs confer specificity to T cells and trigger their activation. Receptors with Ab-derived binding domains have the advantages of MHC-independent Ag recognition and of targeting a variety of chemically different molecules. We explored the impact of the position of a defined epitope within the target molecule on the efficacy of receptor-mediated T cell activation. T cells were grafted with recombinant immunoreceptors that recognize either the membrane distal N or the proximal A3 domain of carcinoembryonic Ag (CEA). Upon binding to isolated, solid-phase immobilized CEA, receptor-mediated T cell activation correlates with the binding efficiency, irrespectively, of the epitope position. Upon binding to CEA expressed on the cell membrane, in contrast, the A3 epitope mediates more efficiently T cell activation than the N epitope, although the N epitope is bound with higher affinity. The CEA N epitope when expressed in a more membrane proximal position, however, activated receptor grafted T cells with higher efficiency than in the distal position. The position of the targeted epitope within the molecule obviously has major impact on the efficacy of T cell activation independently of the binding efficiency of the immunoreceptor.
Augmentation of NZB Autoimmune Phenotypes by the Sle1c Murine Lupus Susceptibility Interval
Authors: Giles Brendan M. , Tchepeleva Svetlana N. , Kachinski Julie J. , Ruff Katherine , Croker Byron P. , Morel Laurence , Boackle Susan A.
Published: April 2014

The Sle1c lupus susceptibility interval spans a 7-Mb region on distal murine chromosome 1. Cr2 is the strongest candidate gene for lupus susceptibility in this interval, as its protein products are structurally and functionally altered. B6.Sle1c congenic mice develop Abs to chromatin by 9 mo of age with a 30% penetrance and do not develop GN. To determine whether the New Zealand White (NZW)-derived Sle1c interval would interact with New Zealand Black (NZB) genes to result in enhanced autoimmune phenotypes, NZB mice were bred with B6 or B6.Sle1c congenic mice and ∼20 female offspring were selected from each breeding for longitudinal study. These mice differ only at the Sle1c locus at which they have either a NZB/B6 or NZB/NZW genotype. NZB × B6.Sle1c mice had an accelerated onset of anti-chromatin Abs (100 vs 68% at 6 mo, p = 0.006) and anti-dsDNA Abs (45 vs 5% at 9 mo, p = 0.0048). Furthermore, median titers of anti-chromatin and anti-dsDNA Abs were significantly higher in the NZB × B6.Sle1c group compared with the NZB × B6 group. This corresponded with a higher prevalence of proliferative GN at 12 mo (55 vs 16%, p = 0.0214) as well as increased glomerular deposition of C3 (p = 0.0272) and IgG (p = 0.032), although blood urea nitrogen remained normal and significant proteinuria was not identified in either group. These data show that the Sle1c interval accelerates and augments the loss of tolerance to chromatin and dsDNA induced by NZB genes and induces significantly greater end-organ damage.
Intratumoral Injection of α-gal Glycolipids Induces Xenograft-Like Destruction and Conversion of Lesions into Endogenous Vaccines
Authors: Galili Uri , Wigglesworth Kim , Abdel-Motal Ussama M.
Published: April 2014

This study describes a novel cancer immunotherapy treatment that exploits the natural anti-Gal Ab to destroy tumor lesions and convert them into an endogenous vaccine targeted to APC via FcγR. Anti-Gal constitutes 1% of immunoglobulins in humans and interacts specifically with α-gal epitopes (Galα1-3Galβ1-4GlcNAc-R). The binding of anti-Gal to α-gal epitopes on pig cells mediates xenograft rejection. The proposed method uses glycolipid micelles with multiple α-gal epitopes (α-gal glycolipids). These glycolipids are extracted from rabbit red cell membranes and are comprised of ceramides with carbohydrate chains containing 5–25 carbohydrates, all capped with α-gal epitopes. Efficacy of this treatment was demonstrated in α1,3-galactosyltransferase knockout mice producing anti-Gal and bearing B16 melanoma or B16/OVA producing OVA as a surrogate tumor Ag. These mice are unique among nonprimate mammals in that, similar to humans, they lack α-gal epitopes and can produce the anti-Gal Ab. Intratumoral injection of α-gal glycolipids results in local inflammation mediated by anti-Gal binding to the multiple α-gal epitopes and activation of complement. These glycolipids spontaneously insert into tumor cell membranes. The binding of anti-Gal to α-gal expressing tumor cells induces the destruction of treated lesions as in anti-Gal-mediated xenograft rejection. Anti-Gal further opsonizes tumor cells within the lesion and, thus, targets them for effective uptake by APC that transport the tumor Ags to draining lymph nodes. APC further cross-present immunogenic tumor Ag peptides and elicit a systemic anti-tumor immune response. Similar intratumoral injection of α-gal glycolipids in humans is likely to induce the destruction of treated lesions and elicit a protective immune response against micrometastases.
Drosophila Hemopoiesis and Cellular Immunity
Authors: Williams Michael J.
Published: April 2014

In Drosophila melanogaster larvae, three classes of circulating cellular immune surveillance cells (hemocytes) can be identified: plasmatocytes, crystal cells, and lamellocytes. Plasmatocytes are professional phagocytes most similar to the mammalian monocyte/macrophage lineage and make up ∼95% of circulating hemocytes. The other ∼5% of circulating hemocytes consists of crystal cells, which secrete components necessary for the melanization of invading organisms, as well as for wound repair. A third cell type known as lamellocytes are rarely seen in healthy larvae and are involved in the encapsulation of invading pathogens. There are no obvious mammalian counterparts for crystal cells or lamellocytes, and there is no equivalent to the lymphoid lineage in insects. In this review, I will discuss what is currently known about Drosophila hemopoiesis and the cellular immune response and where possible compare it to vertebrate mechanisms.
Cutting Edge: Tlr5−/− Mice Are More Susceptible to Escherichia coli Urinary Tract Infection
Authors: Andersen-Nissen Erica , Hawn Thomas R. , Smith Kelly D. , Nachman Alex , Lampano Aaron E. , Uematsu Satoshi , Akira Shizuo , Aderem Alan
Published: April 2014

Although TLR5 regulates the innate immune response to bacterial flagellin, it is unclear whether its function is essential during in vivo murine infections. To examine this question, we challenged Tlr5−/− mice transurethrally with Escherichia coli. At 2 days postinfection, wild-type mice exhibited increased inflammation of the bladder in comparison to Tlr5−/− mice. By day 5 postinfection, Tlr5−/− mice had significantly more bacteria in the bladders and kidneys in comparison to wild-type mice and showed increased inflammation in both organs. In addition, flagellin induced high levels of cytokine and chemokine expression in the bladder that was dependent on TLR5. Together, these data represent the first evidence that TLR5 regulates the innate immune response in the urinary tract and is essential for an effective murine in vivo immune response to an extracellular pathogen.
Cutting Edge: Antigen Is Not Required for the Activation and Maintenance of Virus-Specific Memory CD8+ T Cells in the Lung Airways
Authors: Kohlmeier Jacob E. , Miller Shannon C. , Woodland David L.
Published: April 2014

Respiratory virus infections establish a population of memory CD8+ T cells in the lung airways that persist for months after infection. However, the relationship between Ag-specific memory T cells in the lung airways and the systemic memory T cell pool is not well understood. The majority of lung airway memory T cells express a highly activated phenotype (CD69+/CD127−), suggesting that recent Ag stimulation is required to drive T cell activation and recruitment to the lung airways. In this study, we demonstrate that the lung airway environment itself in the absence of cognate Ag alters the expression of acute activation markers such as CD69 and CD127 on memory CD8+ T cells. Furthermore, the steady-state recruitment of virus-specific memory CD8+ T cells to the lung airways from the circulation can occur without recent Ag stimulation. These findings alter the current perceptions concerning the contribution of Ag to the maintenance of peripheral T cell memory.
Dissociation of Experimental Allergic Encephalomyelitis Protective Effect and Allergic Side Reactions in Tolerization with Neuroantigen
Authors: Lichtenegger Felix S. , Kuerten Stefanie , Faas Susan , Boehm Bernhard O. , Tary-Lehmann Magdalena , Lehmann Paul V.
Published: April 2014

Administration of autoantigens under conditions that induce type 2 immunity frequently leads to protection from T cell-mediated autoimmune diseases. Such treatments, however, are inherently linked to the induction of IgG1 Abs and to the risk of triggering anaphylactic reactions. We studied the therapeutic benefit vs risk of immune deviation in experimental allergic encephalomyelitis of SJL mice induced by MP4, a myelin basic protein-proteolipid protein (PLP) fusion protein. MP4 administration in IFA induced type 2 T cell immunity, IgG1 Abs, and experimental allergic encephalomyelitis protection, and all three were enhanced by repeat injections. Despite high Ab titers, anaphylactic side reactions were not observed when MP4 was repeatedly injected in IFA or as soluble Ag s.c. In contrast, lethal anaphylaxis was seen after s.c. injection of soluble PLP:139–151 peptide, but not when the peptide was reinjected in IFA. Therefore, the Ab response accompanying the immune therapy constituted an anaphylactic risk factor only when the autoantigen was not retained in an adjuvant and when it was small enough to be readily disseminated within the body. Taken together, our data show that treatment regimens can be designed to boost the protective type 2 T cell response while avoiding the risk of Ab-mediated allergic side effects.
An Essential Role for IL-18 in CD8 T Cell-Mediated Suppression of IgE Responses
Authors: Salagianni Maria , Loon Wong Kok , Thomas Matthew J. , Noble Alistair , Kemeny David M.
Published: April 2014

The ability of CD8 T cells to suppress IgE responses is well established. Previously, we demonstrated that CD8 T cells inhibit IgE responses via the induction of IL-12, which promotes Th1 and suppresses Th2 responses. In this study, we show that IL-18 also plays an essential role in IgE suppression. In vitro, IL-18 synergized with IL-12 to promote Th1/T cytotoxic 1 and inhibit Th2/T cytotoxic 2 differentiation. OVA-specific TCR transgenic (OT-I) CD8 cells induced both IL-12 and IL-18 when cultured with OVA257–264 peptide-pulsed dendritic cells. In vivo, IL-18−/− mice exhibited higher IgE and IgG1 levels compared with wild-type mice after immunization with OVA/alum. Furthermore, adoptive transfer of CD8 T cells from OVA-primed mice suppressed IgE responses in OVA/alum-immunized mice, but not in IL-18−/− mice. IgE suppression in IL-18−/− mice was restored if CD8 T cells were coadoptively transferred with IL-18-competent wild-type bone marrow dendritic cell progenitors, demonstrating an essential role of IL-18 in CD8 T cell-mediated suppression of IgE responses. The data suggest that CD8 T cells induce IL-18 production during a cognate interaction with APCs that synergizes with IL-12 to promote immune deviation away from the allergic phenotype. Our data identify IL-18 induction as a potentially useful target in immunotherapy of allergic disease.