bluuebunny/crossref_metadata_2025 huggingface dataset:
B7-DC/PD-L2 Cross-Linking Induces NF-κB-Dependent Protection of Dendritic Cells from Cell Death
Authors: Radhakrishnan Suresh , Nguyen Loc T. , Ciric Bogoljub , Van Keulen Virginia P. , Pease Larry R.
Published: April 2014

Cross-linking cell surface molecules with IgM Abs is a specific approach for activating cells in vitro or in vivo. Dendritic cells (DC) activated with a human B7-DC (PD-L2)-specific IgM Ab can induce strong antitumor responses and block inflammatory airway disease in experimental models, yet the Ab-mediated molecular events promoting these responses remain unclear. Analysis of human or mouse DC treated with the B7-DC cross-linking Ab revealed PI3K-dependent phosphorylation of AKT accompanied by mobilization of NF-κB. Ab-activated DC up-regulated expression of cytokine and chemokine genes in an NF-κB-dependent manner. Importantly, PI3K→AKT→NF-κB activation was found to be indispensable for B7-DC cross-linking Ab-mediated protection of DC from cell death caused by cytokine withdrawal. Although other DC activators similarly protect DC from cell death, a synergy between cross-linking B7-DC and ligating RANK was observed. The parallel signaling events induced in human and mouse DC demonstrate that activation of cells using IgM Ab results in a response governed by a common mechanism and support the hypothesis that B7-DC cross-linking using this Ab may provide beneficial therapeutic immune modulation in human patients similar to those seen in animal models.
Naturally Occurring Lung CD4+CD25+ T Cell Regulation of Airway Allergic Responses Depends on IL-10 Induction of TGF-β
Authors: Joetham Anthony , Takada Katsuyuki , Taube Christian , Miyahara Nobuaki , Matsubara Satoko , Koya Toshiyuki , Rha Yeong-Ho , Dakhama Azzeddine , Gelfand Erwin W.
Published: April 2014

Peripheral tolerance to allergens is mediated in large part by the naturally occurring lung CD4+CD25+ T cells, but their effects on allergen-induced airway responsiveness have not been well defined. Intratracheal, but not i.v., administration of naive lung CD4+CD25+ T cells before allergen challenge of sensitized mice, similar to the administration of the combination of rIL-10 and rTGF-β, resulted in reduced airway hyperresponsiveness (AHR) and inflammation, lower levels of Th2 cytokines, higher levels of IL-10 and TGF-β, and less severe lung histopathology. Significantly, CD4+CD25+ T cells isolated from IL-10−/− mice had no effect on AHR and inflammation, but when incubated with rIL-10 before transfer, suppressed AHR, and inflammation, and was associated with elevated levels of bronchoalveolar lavage TGF-β levels. By analogy, anti-TGF-β treatment reduced regulatory T cell activity. These data identify naturally occurring lung CD4+CD25+ T cells as capable of regulating lung allergic responses in an IL-10- and TGF-β-dependent manner.
Targeting of CD25 and Glucocorticoid-Induced TNF Receptor Family-Related Gene-Expressing T Cells Differentially Modulates Asthma Risk in Offspring of Asthmatic and Normal Mother Mice
Authors: Hubeau Cedric , Apostolou Irina , Kobzik Lester
Published: April 2014

Immunological mechanisms leading to increased asthma susceptibility in early life remain obscure. In this study, we examined the effects of neonatal Ab treatments targeting T cell populations on the development of an asthma syndrome. We used a model of increased asthma susceptibility where offspring of asthmatic BALB/c mother mice are more prone (than normal pups) to develop the disease. Neonatal pretreatment of naive pups with mAb directed against the IL-2Rα chain (CD25), the costimulatory molecule glucocorticoid-induced TNFR family related gene, and the inhibitory molecule CTLA-4 elicited contrasting effects in offspring depending on the mother’s asthma status. Specifically, neonatal CD25high T cell depletion stimulated asthma susceptibility in normal offspring whereas it ameliorated the condition of pups born of asthmatic mothers. Conversely, glucocorticoid-induced TNFR family related gene ligation as a primary signal reduced the spleen cellularity and largely abrogated asthma susceptibility in asthma-prone offspring, without inducing disease in normal pups. Striking changes in Th1/Th2 cytokine levels, especially IL-4, followed mAb pretreatment and were consistent with the impact on asthma susceptibility. These results point to major differences in neonatal T cell population and responsiveness related to maternal asthma history. Interventions that temporarily remove and/or inactivate specific T cell subsets may therefore prove useful to attenuate early life asthma susceptibility and prevent the development of Th2-driven allergic airway disease.
BTNL2, a Butyrophilin/B7-Like Molecule, Is a Negative Costimulatory Molecule Modulated in Intestinal Inflammation
Authors: Arnett Heather A. , Escobar Sabine S. , Gonzalez-Suarez Eva , Budelsky Alison L. , Steffen Lori A. , Boiani Norman , Zhang Ming , Siu Gerald , Brewer Avery W. , Viney Joanne L.
Published: April 2014

Butyrophilin-like 2 (BTNL2) is a butyrophilin family member with homology to the B7 costimulatory molecules, polymorphisms of which have been recently associated through genetic analyses to sporadic inclusion body myositis and sarcoidosis. We have characterized the full structure, expression, and function of BTNL2. Structural analysis of BTNL2 shows a molecule with an extracellular region containing two sets of two Ig domains, a transmembrane region, and a previously unreported cytoplasmic tail. Unlike most other butyrophilin members, BTNL2 lacks the prototypical B30.2 ring domain. TaqMan and Northern blot analysis indicate BTNL2 is predominantly expressed in digestive tract tissues, in particular small intestine and Peyer’s patches. Immunohistochemistry with BTNL2-specific Abs further localizes BTNL2 to epithelial and dendritic cells within these tissues. Despite its homology to the B7 family, BTNL2 does not bind any of the known B7 family receptors such as CD28, CTLA-4, PD-1, ICOS, or B and T lymphocyte attenuator. Because of its localization in the gut and potential role in the immune system, BTNL2 expression was analyzed in a mouse model of inflammatory bowel disease. BTNL2 is overexpressed during both the asymptomatic and symptomatic phase of the Mdr1a knockout model of spontaneous colitis. In functional assays, soluble BTNL2-Fc protein inhibits the proliferation of murine CD4+ T cells from the spleen, mesenteric lymph node, and Peyer’s patch. In addition, BTNL2-Fc reduces proliferation and cytokine production from T cells activated by anti-CD3 and B7-related protein 1. These data suggest a role for BTNL2 as a negative costimulatory molecule with implications for inflammatory disease.
Secretory Antibody Formation: Conserved Binding Interactions between J Chain and Polymeric Ig Receptor from Humans and Amphibians
Authors: Braathen Ranveig , Hohman Valerie S. , Brandtzaeg Per , Johansen Finn-Eirik
Published: April 2014

Abs of the secretory Ig (SIg) system reinforce numerous innate defense mechanisms to protect the mucosal surfaces against microbial penetration. SIgs are generated by a unique cooperation between two distinct cell types: plasma cells that produce polymers of IgA or IgM (collectively called pIgs) and polymeric Ig receptor (pIgR)-expressing secretory epithelial cells that mediate export of the pIgs to the lumen. Apical delivery of SIgs occurs by cleavage of the pIgR to release its extracellular part as a pIg-bound secretory component, whereas free secretory components are derived from an unoccupied receptor. The joining chain (J chain) is crucial in pIg/SIg formation because it serves to polymerize Igs and endows them with a binding site for the pIgR. In this study, we show that the J chain from divergent tetrapods including mammals, birds, and amphibians efficiently induced polymerization of human IgA, whereas the J chain from nurse shark (a lower vertebrate) did not. Correctly assembled polymers showed high affinity to human pIgR. Sequence analysis of the J chain identified two regions, conserved only in tetrapods, which by mutational analysis were found essential for pIgA-pIgR complexing. Furthermore, we isolated and characterized pIgR from the amphibian Xenopus laevis and demonstrated that its pIg binding domain showed high affinity to human pIgA. These results showed that the functional site of interaction between pIgR, J chain and Ig H chains is conserved in these species and suggests that SIgs originated in an ancestor common to tetrapods.
Suppression of Early IL-4 Production Underlies the Failure of CD4 T Cells Activated by TLR-Stimulated Dendritic Cells to Differentiate into Th2 Cells
Authors: Sun Jie , Pearce Edward J.
Published: April 2014

Dendritic cells (DCs) activated through TLRs provide a potent negative signal for Th2 cell development that is independent of positive signals for Th1 cell development such as IL-12 and IFN-γ. In this study we demonstrate that the ability of TLR-activated DCs to suppress Th2 cell development is Ag dose-independent and unique to DCs that have been activated through TLRs vs by cytokines. We show that TLR-activated DCs inhibit early IL-4 production by CD4 T cells and thus inhibit their ability to subsequently increase GATA-3 expression and commit to the Th2 lineage. This occurs independently of expression of the GATA-3 antagonist T-bet. Although CD4 T cells activated by TLR-activated DCs make IL-2, they are not capable of phosphorylating STAT5 in response to this cytokine. This inhibition of responsiveness to IL-2 appears to underlie the failure to make early IL-4. Our findings suggest that DCs provide instructional signals for T cell differentiation before cytokine-mediated Th cell selection and outgrowth.
Fiber-Modified Adenovirus Vectors Decrease Liver Toxicity through Reduced IL-6 Production
Authors: Koizumi Naoya , Yamaguchi Tomoko , Kawabata Kenji , Sakurai Fuminori , Sasaki Tomomi , Watanabe Yoshiteru , Hayakawa Takao , Mizuguchi Hiroyuki
Published: April 2014

Adenovirus (Ad) vectors are one of the most commonly used viral vectors in gene therapy clinical trials. However, they elicit a robust innate immune response and inflammatory responses. Improvement of the therapeutic index of Ad vector gene therapy requires elucidation of the mechanism of Ad vector-induced inflammation and cytokine/chemokine production as well as development of the safer vector. In the present study, we found that the fiber-modified Ad vector containing poly-lysine peptides in the fiber knob showed much lower serum IL-6 and aspartate aminotransferase levels (as a maker of liver toxicity) than the conventional Ad vector after i.v. administration, although the modified Ad vector showed higher transgene production in the liver than the conventional Ad vector. RT-PCR analysis showed that spleen, not liver, is the major site of cytokine, chemokine, and IFN expression. Splenic CD11c+ cells were found to secret cytokines. The tissue distribution of Ad vector DNA showed that spleen distribution was much reduced in this modified Ad vector, reflecting reduced IL-6 levels in serum. Liver toxicity by the conventional Ad vector was reduced by anti-IL-6R Ab, suggesting that IL-6 signaling is involved in liver toxicity and that decreased liver toxicity of the modified Ad vector was due in part to the reduced IL-6 production. This study contributes to an understanding of the biological mechanism in innate immune host responses and liver toxicity toward systemically administered Ad vectors and will help in designing safer gene therapy methods that can reduce robust innate immunity and inflammatory responses.
C3a Is Required for the Production of CXC Chemokines by Tubular Epithelial Cells after Renal Ishemia/Reperfusion
Authors: Thurman Joshua M. , Lenderink Amanda M. , Royer Pamela A. , Coleman Kathrin E. , Zhou Jian , Lambris John D. , Nemenoff Raphael A. , Quigg Richard J. , Holers V. Michael
Published: April 2014

The complement system is one of the major ways by which the body detects injury to self cells, and the alternative pathway of complement is rapidly activated within the tubulointerstitium after renal ischemia/reperfusion (I/R). In the current study, we investigate the hypothesis that recognition of tubular injury by the complement system is a major mechanism by which the systemic inflammatory response is initiated. Gene array analysis of mouse kidney following I/R initially identified MIP-2 (CXCL2) and keratinocyte-derived chemokine (KC or CXCL1) as factors that are produced in a complement-dependent fashion. Using in situ hybridization, we next demonstrated that these factors are expressed in tubular epithelial cells of postischemic kidneys. Mouse proximal tubular epithelial cells (PTECs) in culture were then exposed to an intact alternative pathway and were found to rapidly produce both chemokines. Selective antagonism of the C3a receptor significantly attenuated production of MIP-2 and KC by PTECs, whereas C5a receptor antagonism and prevention of membrane attack complex (MAC) formation did not have a significant effect. Treatment of PTECs with an NF-κB inhibitor also prevented full expression of these factors in response to an intact alternative pathway. In summary, alternative pathway activation after renal I/R induces production of MIP-2 and KC by PTECs. This innate immune system thereby recognizes hypoxic injury and triggers a systemic inflammatory response through the generation of C3a and subsequent activation of the NF-κB system.
High Concentration of Antioxidants N-Acetylcysteine and Mitoquinone-Q Induces Intercellular Adhesion Molecule 1 and Oxidative Stress by Increasing Intracellular Glutathione
Authors: Mukherjee Tapan K. , Mishra Anurag K. , Mukhopadhyay Srirupa , Hoidal John R.
Published: April 2014

In endothelial cells, the intracellular level of glutathione is depleted during offering protection against proinflammatory cytokine TNF-α-induced oxidative stress. Administration of anti-inflammatory drugs, i.e., N-acetylcysteine (NAC) or mitoquinone-Q (mito-Q) in low concentrations in the human pulmonary aortic endothelial cells offered protection against depletion of reduced glutathione and oxidative stress mediated by TNF-α. However, this study addressed that administration of NAC or mito-Q in high concentrations resulted in a biphasic response by initiating an enhanced generation of both reduced glutathione and oxidized glutathione and enhanced production of reactive oxygen species, along with carbonylation and glutathionylation of the cellular proteins. This study further addressed that IκB kinase (IKK), a phosphorylation-dependent regulator of NF-κB, plays an important regulatory role in the TNF-α-mediated induction of the inflammatory cell surface molecule ICAM-1. Of the two catalytic subunits of IKK (IKKα and IKKβ), low concentrations of NAC and mito-Q activated IKKα activity, thereby inhibiting the downstream NF-κB and ICAM-1 induction by TNF-α. High concentrations of NAC and mito-Q instead caused glutathionylation of IKKα, thereby inhibiting its activity that in turn enhanced the downstream NF-κB activation and ICAM-1 expression by TNF-α. Thus, establishing IKKα as an anti-inflammatory molecule in endothelial cells is another focus of this study. This is the first report that describes a stressful situation in the endothelial cells created by excess of antioxidative and anti-inflammatory agents NAC and mito-Q, resulting in the generation of reactive oxygen species, carbonylation and glutathionylation of cellular proteins, inhibition of IKKα activity, and up-regulation of ICAM-1expression.
Identification of pH-Regulated Antigen 1 Released from Candida albicans as the Major Ligand for Leukocyte Integrin αMβ2
Authors: Soloviev Dmitry A. , Fonzi William A. , Sentandreu Rafael , Pluskota Elzbieta , Forsyth Christopher B. , Yadav Satya , Plow Edward F.
Published: April 2014

Candida albicans is a common opportunistic fungal pathogen and is the leading cause of invasive fungal disease in immunocompromised individuals. The induction of cell-mediated immunity to C. albicans is of critical importance in host defense and the prime task of cells of the innate immune system. We previously demonstrated that the integrin αMβ2 (CD11b/CD18) is the major leukocyte receptor involved in C. albicans recognition, mediating both adhesive and migratory responses to the fungus. In the present study, we demonstrate that various C. albicans strains release a protease-sensitive activity into their conditioned medium that supports αMβ2-mediated cell adhesion and migration. The isolation and characterization of this protein was undertaken by two independent approaches: 1) immunoaffinity purification on a mAb raised to conditioned medium which blocked αMβ2-dependent adhesion and migration; and 2) affinity chromatography on purified αMβ2. Each approach led to the isolation of the same protein, which was unequivocally identified as pH-regulated Ag 1 (Pra1p), based on mass spectrometry and amino acid sequence analyses. C. albicans mutant strains lacking Pra1p were unable to support leukocyte adhesion or migration. In a neutrophil-mediated fungal killing assay, such mutant strains were resistant to killing and/or phagocytosis. Addition of purified Pra1p or reagents that block αMβ2 function prevented killing of Pra1p-expressing but not Pra1p-deficient strains of C. albicans. Together, these data indicate that Pra1p is a ligand of αMβ2 on C. albicans and that the soluble form of Pra1p may assist the fungus in escaping host surveillance.
Differential CD40/CD40L Expression Results in Counteracting Antitumor Immune Responses
Authors: Murugaiyan Gopal , Agrawal Reena , Mishra Gyan C. , Mitra Debashis , Saha Bhaskar
Published: April 2014

Establishment of host-protective memory T cells against tumors is the objective of an antitumor immunoprophylactic strategy such as reinforcing T cell costimulation via CD40-CD40L interaction. Previous CD40-targeted strategies assumed that T cell costimulation is an all-or-none phenomenon. It was unknown whether different levels of CD40L expression induce quantitatively and qualitatively different effector T cell responses. Using mice expressing different levels of CD40L, we demonstrated that the greater the T cell CD40L expression the less tumor growth occurred; the antitumor T cell response was host-protective. Lower levels of CD40L expression on T cells induced IL-10-mediated suppression of tumor-regressing effector CD8+ T cells and higher productions of IL-4 and IL-10. Using mice expressing different levels of CD40 or by administering different doses of anti-CD40 Ab, similar observations were recorded implying that the induction of protumor or antitumor T cell responses was a function of the extent of CD40 cross-linking. IL-10 neutralization during priming with tumor Ags resulted in a stronger tumor-regressing effector T cell response. Using IL-10−/− DC for priming of mice expressing different levels of CD40L and subsequent transfer of the T cells from the primed mice to nu/nu mice, we demonstrated the protumor role of IL-10 in the induction of tumor-promoting T cells. Our results demonstrate that a dose-dependent cross-linking of a costimulatory molecule dictates the functional phenotype of the elicited effector T cell response. The T cell costimulation is a continuum of a function that induces not only graded T cell responses but also two counteracting responses at two extremes.
Cognate CD4+ Help Elicited by Resting Dendritic Cells Does Not Impair the Induction of Peripheral Tolerance in CD8+ T Cells
Authors: Steptoe Raymond J. , Ritchie Janine M. , Wilson Nicholas S. , Villadangos Jose A. , Lew Andrew M. , Harrison Leonard C.
Published: April 2014

Peripheral tolerance is required to prevent autoimmune tissue destruction by self-reactive T cells that escape negative selection in the thymus. One mechanism of peripheral tolerance in CD8+ T cells is their activation by resting dendritic cells (DC). In contrast, DC can be “licensed” by CD4+ T cells to induce cytotoxic function in CD8+ T cells. The question that then arises, whether CD4+ T cell help could impair peripheral tolerance induction in self-reactive CD8+ T cells, has not been addressed. In this study we show that CD4+ T cell activation by resting DC results in helper function that transiently promotes the expansion and differentiation of cognate CD8+ T cells. However, both the CD4+ and CD8+ T cell populations ultimately undergo partial deletion and acquire Ag unresponsiveness, disabling their ability to destroy OVA-expressing pancreatic β cells and cause diabetes. Thus, effective peripheral tolerance can be induced by resting DC in the presence of CD4+ and CD8+ T cells with specificity for the same Ag.
Natural Regulatory T Cells and De Novo-Induced Regulatory T Cells Contribute Independently to Tumor-Specific Tolerance
Authors: Zhou Gang , Levitsky Hyam I.
Published: April 2014

Thymus-derived, naturally occurring CD4+CD25+Foxp3+ regulatory T cells (nTregs) and Tregs induced in the periphery (iTregs) have both been implicated in regulating immune responses. However, the relationship between these populations in the same host, and their relative contribution to the overall Treg pool, has not been examined. Using a tumor-induced T cell tolerance model, we find that expansion of nTregs and de novo generation of iTregs both contribute to tumor-specific T cell tolerance. In this system in which the number of tumor-specific nTregs can be controlled, the efficiency of nTreg expansion significantly exceeds that of the induction of Tregs from uncommitted progenitors in the tumor-bearing host. However, pre-existing nTregs are neither required for the induction of Tregs nor measurably impact on the extent of their accumulation. Instead, induction of Ag-specific regulatory cells from naive cells is intrinsically influenced by the tumor microenvironment and the presence of tumor Ag.
Insect Baculoviruses Strongly Potentiate Adaptive Immune Responses by Inducing Type I IFN
Authors: Hervas-Stubbs Sandra , Rueda Paloma , Lopez Lissette , Leclerc Claude
Published: April 2014

Baculoviruses (BVs) are dsDNA viruses that are pathogenic for insects. They have been used worldwide as selective bioinsecticides and for producing recombinant proteins in insect cells. Surprisingly, despite their widespread use in research and industry and their dissemination in the environment, the potential effects of these insect viruses on the immune responses of mammals remain totally unknown. We show in this study that BVs have strong adjuvant properties in mice, promoting potent humoral and CD8+ T cell adaptive responses against coadministered Ag. BVs also induce the in vivo maturation of dendritic cells and the production of inflammatory cytokines. We demonstrate that BVs play a major role in the strong immunogenicity of virus-like particles produced in the BV-insect cell expression system. The presence of even small numbers of BVs among the recombinant proteins produced in the BV expression system may therefore strengthen the immunological properties of these proteins. This adjuvant behavior of BVs is mediated primarily by IFN-αβ, although mechanisms independent of type I IFN signaling are also involved. This study demonstrates that nonpathogenic insect viruses may have a strong effect on the mammalian immune system.
Evidence for Phagocytosis of Influenza Virus-Infected, Apoptotic Cells by Neutrophils and Macrophages in Mice
Authors: Hashimoto Yumi , Moki Takeshi , Takizawa Takenori , Shiratsuchi Akiko , Nakanishi Yoshinobu
Published: April 2014

Influenza virus-infected cells undergo apoptosis and become susceptible to phagocytosis by macrophages in vitro, and this leads to the propagation of the virus being inhibited. We previously showed that inhibitors of phagocytosis increased the rate of mortality among influenza virus-infected mice. However, the mode of the phagocytosis of influenza virus-infected cells in vivo has not been investigated. We, in this study, assessed this issue by histochemically analyzing bronchoalveolar lavage cells and lung tissue obtained from C57BL/6 mice infected with influenza A/WSN (H1N1) virus. Both neutrophils and macrophages accumulated in the lung soon after the viral challenge, and either type of cell was capable of phagocytosing influenza virus-infected, apoptotic cells. Changes in the level of phagocytosis and the amount of virus in lung tissue roughly correlated with each other. Furthermore, alveolar macrophages prepared from influenza virus-infected mice showed greater phagocytic activity than those from uninfected mice. The phagocytic activity of macrophages was stimulated in vitro by a heat-labile substance(s) released from influenza virus-infected cells undergoing apoptosis. These results suggested that the level of phagocytosis is augmented both quantitatively and qualitatively in the lung of influenza virus-infected animals so that infected cells are effectively eliminated. Finally, lack of TLR4 caused an increase in the rate of mortality among influenza virus-challenged mice and a decrease in the level of phagocytosis of apoptotic cells in the lung. TLR4 could thus play an important role in the host defense against influenza by positively regulating the phagocytic elimination of infected cells.
FTY720 Ameliorates Th1-Mediated Colitis in Mice by Directly Affecting the Functional Activity of CD4+CD25+ Regulatory T Cells
Authors: Daniel Carolin , Sartory Nico , Zahn Nadine , Geisslinger Gerd , Radeke Heinfried H. , Stein Juergen M.
Published: April 2014

Following the present concepts, the synthetic sphingosine analog of myriocin FTY720 alters migration and homing of lymphocytes via sphingosine 1-phosphate receptors. However, several studies indicate that the immunosuppressive properties of FTY720 may alternatively be due to tolerogenic activities via modulation of dendritic cell differentiation or based on direct effects on CD4+CD25+ regulatory T cells (Treg). As Treg play an important role for the cure of inflammatory colitis, we used the Th1-mediated 2,4,6-trinitrobenzene sulfonic acid (TNBS) colitis model to address the therapeutic potential of FTY720 in vivo. A rectal enema of TNBS was given to BALB/c mice. FTY720 was administered i.p. from days 0 to 3 or 3 to 5. FTY720 substantially reduced all clinical, histopathologic, macroscopic, and microscopic parameters of colitis analyzed. The therapeutic effects of FTY720 were associated with a down-regulation of IL-12p70 and subsequent Th1 cytokines. Importantly, FTY720 treatment resulted in a prominent up-regulation of FoxP3, IL-10, TGFβ, and CTLA4. Supporting the hypothesis that FTY720 directly affects functional activity of CD4+CD25+ Treg, we measured a significant increase of CD25 and FoxP3 expression in isolated lamina propria CD4+ T cells of FTY720-treated mice. The impact of FTY720 on Treg induction was further confirmed by concomitant in vivo blockade of CTLA4 or IL-10R which significantly abrogated its therapeutic activity. In conclusion, our data provide clear evidence that in addition to its well-established effects on migration FTY720 leads to a specific down-regulation of proinflammatory signals while simultaneously inducing functional activity of CD4+CD25+ Treg. Thus, FTY720 may offer a promising new therapeutic strategy for the treatment of IBD.
Regulation of Th2 Cytokine Genes by p38 MAPK-Mediated Phosphorylation of GATA-3
Authors: Maneechotesuwan Kittipong , Xin Yao , Ito Kazuhiro , Jazrawi Elen , Lee Kang-Yun , Usmani Omar S. , Barnes Peter J. , Adcock Ian M.
Published: April 2014

GATA-3 plays a critical role in allergic diseases by regulating the release of cytokines from Th2 lymphocytes. However, the molecular mechanisms involved in the regulation of GATA-3 in human T lymphocytes are not yet understood. Using small interfering RNA to knock down GATA-3, we have demonstrated its critical role in regulating IL-4, IL-5, and IL-13 release from a human T cell line. Specific stimulation of T lymphocytes by costimulation of CD3 and CD28 to mimic activation by APCs induces translocation of GATA-3 from the cytoplasm to the nucleus, with binding to the promoter region of Th2 cytokine genes, as determined by chromatin immunoprecipitation. GATA-3 nuclear translocation is dependent on its phosphorylation on serine residues by p38 MAPK, which facilitates interaction with the nuclear transporter protein importin-α. This provides a means whereby allergen exposure leads to the expression of Th2 cytokines, and this novel mechanism may provide new approaches to treating allergic diseases.
CD43 Collaborates with P-Selectin Glycoprotein Ligand-1 to Mediate E-Selectin-Dependent T Cell Migration into Inflamed Skin
Authors: Matsumoto Masanori , Shigeta Akiko , Furukawa Yuko , Tanaka Toshiyuki , Miyasaka Masayuki , Hirata Takako
Published: April 2014

Activated T cell migration into nonlymphoid tissues is initiated by the interactions of P- and E-selectin expressed on endothelial cells and their ligands on T cells. P-selectin glycoprotein ligand-1 (PSGL-1) has been the only E-selectin ligand demonstrated to function during the in vivo migration of activated T cells. We show in this study that CD43-deficient Th1 cells, like PSGL-1-deficient cells, exhibited reduced E-selectin-binding activity compared with wild-type cells. Th1 cells with a PSGL-1 and CD43 double deficiency showed even less E-selectin-binding activity. In migration assays in which adoptively transferred cells migrate to inflamed skin P- and E-selectin dependently, CD43 contributed significantly to PSGL-1-independent Th1 cell migration. In addition, in vivo activated T cells from the draining lymph nodes of sensitized mice deficient in PSGL-1 and/or CD43 showed significantly decreased E-selectin-binding activity and migration efficiency, with T cells from double-deficient mice showing the most profound decrease. Collectively, these results demonstrate that the CD43 expressed on activated T cells functions as an E-selectin ligand and thereby mediates T cell migration to inflamed sites, in collaboration with PSGL-1.
Cutting Edge: Bim Is Required for Superantigen-Mediated B Cell Death
Authors: Goodyear Carl S. , Corr Maripat , Sugiyama Fujimi , Boyle David L. , Silverman Gregg J.
Published: April 2014

To impair B cell clonal regulation, the microbial virulence factor, protein A of Staphylococcus aureus, can interact with evolutionarily conserved BCR-binding sites to induce a form of Fas-independent activation-associated B cell death that results in selective immune tolerance. We now show that this in vivo death pathway is associated with induction of increased transcript and protein levels of Bim, a BH3-only proapoptotic Bcl-2 family protein, which is inhibited by excess B cell-activating factor. An absolute requirement for Bim was documented, since Bim-deficient B cells were protected from in vivo superantigen-induced death and instead underwent persistent massive supraclonal expansion without functional impairment. These studies characterize a BCR-dependent negative clonal selection pathway that has been co-opted by a common bacterial pathogen to induce selective defects in host immune defenses.
Fetal Immune Responses to Plasmodium falciparum Antigens in a Malaria-Endemic Region of Cameroon
Authors: Metenou Simon , Suguitan Amorsolo L. , Long Carole , Leke Rose G. F. , Taylor Diane Wallace
Published: April 2014

Plasmodium falciparum infection during pregnancy can lead to the transplacental passage of malarial Ags that are capable of inducing acquired immune responses in the fetus. Studies have identified cytokines produced by malaria-specific cord blood (CB) T cells, but information on fetal B cells is limited. Thus, CB mononuclear cells from 120 Cameroonian newborns were cultured for 7 days in vitro and supernatants were assessed by ELISA for Abs to an extract of malarial schizonts (MA), recombinant apical merozoite Ag 1 (AMA-1), the 42-kDa C-terminal region of merozoite surface protein 1 (MSP-142), a B epitope of ring-infected erythrocyte surface Ag (RESA), and the dominant B epitope of the circumsporozoite protein (CSP). Only 12% of supernatants contained IgM to MA but 78% had IgG to one or more malarial Ags, with 53% having IgG to AMA-1, 38% to MSP-142, 3% to RESA, and 0% to CSP. The Abs to AMA-1 and MSP-142 were predominantly IgG1 and IgG3. CB mononuclear cells were also tested for the ability to secrete cytokines in response to MA and a pool of conserved MSP-1 T cell epitopes. Among the Ag-reactive samples, 39.3% produced only Th2-type cytokines, whereas 60.6% produced a combination of Th1- and Th2-type cytokines. Although a Th2 bias was observed, the in utero cytokine environment was adequate to support isotype switching to cytophilic IgGs, the isotypes that are protective in adults. Because many infants living in a low transmission area are born with malaria-specific B and T cells, the influence of in utero priming on neonatal immunity merits further investigation.
Lack of Effective MUC1 Tumor Antigen-Specific Immunity in MUC1-Transgenic Mice Results from a Th/T Regulatory Cell Imbalance That Can Be Corrected by Adoptive Transfer of Wild-Type Th Cells
Authors: Turner Michael S. , Cohen Patrice A. , Finn Olivera J.
Published: April 2014

Glycoprotein tumor Ag MUC1 is overexpressed on the majority of epithelial adenocarcinomas. CTLs that recognize MUC1 and can kill tumor cells that express this molecule have been found in cancer patients, yet they are present in low frequency and unable to eradicate MUC1+ tumors. Patients also make anti-MUC1 Abs but predominantly of the IgM isotype reflecting the lack of effective MUC1-specific Th responses. Mice transgenic for the human MUC1 gene (MUC1-Tg) are similarly hyporesponsive to MUC1. We used a vaccine consisting of dendritic cells loaded with a long synthetic MUC1 peptide to investigate the fate and function of MUC1-specific CD4+ Th elicited in wild-type (WT) or MUC1-Tg mice or adoptively transferred from vaccinated WT mice. We show that hyporesponsiveness of MUC1-Tg mice to this vaccine is a result of insufficient expansion of Th cells, while at the same time their regulatory T cells are efficiently expanded to the same extent as in WT mice and exert a profound suppression on MUC1-specific B and T cell responses in vivo. Adoptive transfer of WT Th cells relieved this suppression and enhanced T and B cell responses to subsequent MUC1 immunization. Our data suggest that the balance between Th and regulatory T cells is a critical parameter that could be modulated to improve the response to cancer vaccines.
Effect of Both Ultraviolet B Irradiation and Histamine Receptor Function on Allergic Responses to an Inhaled Antigen
Authors: McGlade Jacqueline P. , Gorman Shelley , Lenzo Jason C. , Tan Jamie W. , Watanabe Takeshi , Finlay-Jones John J. , Thomas Wayne R. , Hart Prue H.
Published: April 2014

Exposure of skin to UVB radiation (290–320 nm) modulates the immune system, with most studies showing a suppression of Th1-driven immune responses. This study investigated the effects of UVB on Th2-associated immune responses using a murine model of allergic respiratory inflammation. C57BL/6, histamine receptor-1 knockout (H1RKO), and histamine receptor-2 knockout (H2RKO) mice were exposed to a single 4 kJ/m2 dose of UVB (twice a minimal edemal dose) on shaved dorsal skin 3 days before intranasal sensitization with papain, a cysteine protease homologue of the dust mite allergen Der p 1. H1RKO mice demonstrated enhanced papain-specific inflammatory responses in the lung-draining lymph nodes (LDLNs), whereas the responses of H2RKO mice closely mimicked those of C57BL/6 mice. UVB irradiation 3 days before sensitization reduced in vitro papain-specific proliferation of LDLN cells of C57BL/6 and H1RKO mice but not H2RKO mice 24 h after challenge. The regulatory effect of UVB was transferred by adoptive transfer of unfractionated LDLN cells from UVB-irradiated, papain-sensitized C57BL/6 and H1RKO donor mice in naive recipients of the corresponding strain that were subsequently sensitized and challenged with papain. Additionally, UVB exposure suppressed papain-induced IL-5 and IL-10 production in vitro by LDLN cells from H1RKO mice but not from C57BL/6 mice or H2RKO mice. The results of this study demonstrate systemic immunomodulation of responses to intranasally delivered Ag by UVB irradiation and implicate a role for the H2 receptor in UVB-induced suppression of Ag-specific responses in the draining lymph nodes.
Staphylococcus aureus Protein A Triggers T Cell-Independent B Cell Proliferation by Sensitizing B Cells for TLR2 Ligands
Authors: Bekeredjian-Ding Isabelle , Inamura Seiichi , Giese Thomas , Moll Hermann , Endres Stefan , Sing Andreas , Zähringer Ulrich , Hartmann Gunther
Published: April 2014

B cells possess functional characteristics of innate immune cells, as they can present Ag to T cells and can be stimulated with microbial molecules such as TLR ligands. Because crude preparations of Staphylococcus aureus are frequently used as polyclonal B cell activators and contain potent TLR2 activity, the scope of this study was to analyze the impact of S. aureus-derived TLR2-active substances on human B cell activation. Peripheral B cells stimulated with chemically modified S. aureus cell wall preparations proliferated in response to stimulation with crude cell wall preparations but failed to be activated with pure peptidoglycan, indicating that cell wall molecules other than peptidoglycan are responsible for B cell proliferation. Subsequent analysis revealed that surface protein A (SpA), similar to BCR cross-linking with anti-human Ig, sensitizes B cells for the recognition of cell wall-associated TLR2-active lipopeptides (LP). In marked contrast to TLR7- and TLR9-triggered B cell stimulation, stimulation with TLR2-active LP and SpA or with crude cell wall preparations failed to induce IgM secretion, thereby revealing qualitative differences in TLR2 signaling compared with TLR7/9 signaling. Notably, combined stimulation with SpA plus TLR2 ligands induced vigorous proliferation of a defined B cell subset that expressed intracellular IgM in the presence of IL-2. Conclusion: S. aureus triggers B cell activation via SpA-induced sensitization of B cells for TLR2-active LP. Combined SpA and TLR2-mediated B cell activation promotes B cell proliferation but fails to induce polyclonal IgM secretion as seen after TLR7 and TLR9 ligation.
Tumor Cells Loaded with α-Galactosylceramide Induce Innate NKT and NK Cell-Dependent Resistance to Tumor Implantation in Mice
Authors: Shimizu Kanako , Goto Akira , Fukui Mikiko , Taniguchi Masaru , Fujii Shin-ichiro
Published: April 2014

Dendritic cells (DCs) loaded with α-galactosylceramide (α-GalCer) are known to be active APCs for the stimulation of innate NKT and NK cell responses in vivo. In this study, we evaluated the capacity of non-DCs to present α-GalCer in vitro and in vivo, particularly tumor cells loaded with α-GalCer (tumor/Gal). Even though the tumor cells lacked expression of CD40, CD80, and CD86 costimulatory molecules, the i.v. injection of tumor/Gal resulted in IFN-γ secretion by NKT and NK cells. These innate responses to tumor/Gal, including the induction of IL-12p70, were comparable to or better than α-GalCer-loaded DCs. B16 melanoma cells that were stably transduced to express higher levels of CD1d showed an increased capacity relative to wild-type B16 cells to present α-GalCer in vivo. Three different tumor cell lines, when loaded with α-GalCer, failed to establish tumors upon i.v. injection, and the mice survived for at least 6 mo. The resistance against tumor cells was independent of CD4 and CD8 T cells but dependent upon NKT and NK cells. Mice were protected from the development of metastases if the administration of live B16 tumor cells was followed 3 h or 3 days later by the injection of CD1dhigh-α-GalCer-loaded B16 tumor cells with or without irradiation. Taken together, these results indicate that tumor/Gal are effective APCs for innate NKT and NK cell responses, and that these innate immune responses are able to resist the establishment of metastases in vivo.
Induced SHIP Deficiency Expands Myeloid Regulatory Cells and Abrogates Graft-versus-Host Disease
Authors: Paraiso Kim H. T. , Ghansah Tomar , Costello Amy , Engelman Robert W. , Kerr William G.
Published: April 2014

Graft-vs-host disease (GVHD) is the leading cause of treatment-related death in allogeneic bone marrow (BM) transplantation. Immunosuppressive strategies to control GVHD are only partially effective and often lead to life-threatening infections. We previously showed that engraftment of MHC-mismatched BM is enhanced and GVHD abrogated in recipients homozygous for a germline SHIP mutation. In this study, we report the development of a genetic model in which SHIP deficiency can be induced in adult mice. Using this model, we show that the induction of SHIP deficiency in adult mice leads to a rapid and significant expansion of myeloid suppressor cells in peripheral lymphoid tissues. Consistent with expansion of myeloid suppressor cells, splenocytes and lymph node cells from adult mice with induced SHIP deficiency are significantly compromised in their ability to prime allogeneic T cell responses. These results demonstrate that SHIP regulates homeostatic signals for these immunoregulatory cells in adult physiology. Consistent with these findings, induction of SHIP deficiency before receiving a T cell-replete BM graft abrogates acute GVHD. These findings indicate strategies that target SHIP could increase the efficacy and utility of allogeneic BM transplantation, and thereby provide a curative therapy for a wide spectrum of human diseases.
Mcl-1 Depletion in Apoptosis Elicited by Ionizing Radiation in Peritoneal Resident Macrophages of C3H Mice
Authors: Kubota Yoshihisa , Kinoshita Keiji , Suetomi Katsutoshi , Fujimori Akira , Takahashi Sentaro
Published: April 2014

Remarkably, apoptosis was induced by exposing peritoneal resident macrophages (PRM) of C3H mice, but not other strains of mice, to ionizing radiation. The molecular mechanism of this strain-specific apoptosis in PRM was studied. The apoptosis elicited in C3H mouse PRM 4 h after exposure was effectively blocked by proteasome inhibitors. Irradiation-induced disruption of mitochondrial transmembrane potential and the release of cytochrome c into the cytosol were also suppressed by a proteasome inhibitor but not by a caspase inhibitor. To determine whether the apoptosis occurred due to a depletion of antiapoptotic proteins, Bcl-2 family proteins were examined. Irradiation markedly decreased the level of Mcl-1, but not Bcl-2, Bcl-XL, Bax, A1, or cIAP1. Mcl-1’s depletion was suppressed by a proteasome inhibitor but not by a caspase inhibitor. The amount of Mcl-1 was well correlated with the rate of apoptosis in C3H mouse PRM exposed to irradiation and not affected by irradiation in radioresistant B6 mouse PRM. Irradiation increased rather than decreased the Mcl-1 mRNA expression in C3H mouse PRM. On the other hand, Mcl-1 protein synthesis was markedly suppressed by irradiation. Global protein synthesis was also suppressed by irradiation in C3H mouse PRM but not in B6 mouse PRM. The down-regulation of Mcl-1 expression with Mcl-1-specific small interfering RNA or antisense oligonucleotide significantly induced apoptosis in both C3H and B6 mouse PRM without irradiation. It was concluded that the apoptosis elicited in C3H mouse PRM by ionizing radiation was attributable to the depletion of Mcl-1 through radiation-induced arrest of global protein synthesis.
Peroxisome Proliferator-Activated Receptor γ Is Required for Regulatory CD4+ T Cell-Mediated Protection against Colitis
Authors: Hontecillas Raquel , Bassaganya-Riera Josep
Published: April 2014

Peroxisome proliferator-activated receptor (PPAR) γ activation has been implicated in the prevention of immunoinflammatory disorders; however, the mechanisms of regulation of effector and regulatory CD4+ T cell functions by endogenously activated PPAR-γ remain unclear. We have used PPAR-γ-deficient CD4+ T cells obtained from tissue-specific PPAR-γ null mice (i.e., PPAR-γ fl/fl; MMTV-Cre+) to investigate the role of endogenous PPAR-γ on regulatory T cell (Treg) and effector CD4+ T cell function. Overall, we show that the loss of PPAR-γ results in enhanced Ag-specific proliferation and overproduction of IFN-γ in response to IL-12. These findings correlate in vivo with enhanced susceptibility of tissue-specific PPAR-γ null mice to trinitrobenzene sulfonic acid-induced colitis. Furthermore, the transfer of purified PPAR-γ null CD4+ T cells into SCID recipients results in enteric disease. To test the assertion that the deficiency of PPAR-γ in Treg impairs their ability to prevent effector T cell-induced colitis, we performed cotransfer studies. These studies demonstrate that PPAR-γ-expressing, but not PPAR-γ null Treg, prevent colitis induced by transfer of naive CD4+ T cells into SCID recipients. In line with these findings, the production of IFN-γ by spleen and mesenteric lymph node-derived CD4+ T cells was down-regulated following transfer of PPAR-γ-expressing, but not PPAR-γ null, Treg. In conclusion, our data suggest that endogenous PPAR-γ activation represents a Treg intrinsic mechanism of down-regulation of effector CD4+ T cell function and prevention of colitis.
CC Chemokine Receptor 7 Contributes to Gi-Dependent T Cell Motility in the Lymph Node
Authors: Okada Takaharu , Cyster Jason G.
Published: April 2014

Naive T cells migrate extensively within lymph node (LN) T zones to scan for Ag-bearing dendritic cells. However, the extracellular signals controlling T cell motility in LNs are not well defined. In this study, by real-time imaging of LNs, we show that the inhibition of Gi signaling in T cells severely impairs their migration. The chemokine CCL21, a ligand of CCR7, strongly induces chemokinesis in vitro, and T cell motility in LNs from CCR7 ligand-deficient plt/plt mice was reduced. CCR7-deficient T cells in wild-type LNs showed a similar reduction in motility, and antagonism of CXCR4 function did not further decrease their motility. The effect of CCR7 or CCR7-ligand deficiency could account for ∼40% of the Gi-dependent motility. These results reveal a role for CCR7 in promoting T cell migration within lymphoid organ T zones, and they suggest the additional involvement of novel Gi-coupled receptors in promoting T cell motility at these sites.
Conformational Changes in Mannan-Binding Lectin Bound to Ligand Surfaces
Authors: Dong Mingdong , Xu Sailong , Oliveira Cristiano L. P. , Pedersen Jan S. , Thiel Steffen , Besenbacher Flemming , Vorup-Jensen Thomas
Published: April 2014

The binding of soluble proteins to target surfaces is vital in triggering the immune response. However, structural insight into such processes is still lacking. Mannan-binding lectin (MBL) is a classic example of a pattern recognition molecule with important roles in innate immunity against microbial infections. By small angle x-ray scattering analysis we show that the large MBL complex in solution is folded into a ramified structure with a striking rotational symmetry and a structure permissive of elongation by unbending. Nevertheless, the structure in solution is found to be very stable. However, when the MBL molecule interacts with surface-immobilized ligands, the stable MBL structure is broken into a stretched state with separation of the ligand-binding domains as shown by high resolution atomic force microscopy. These studies provide a snapshot of the single molecule mechanics of MBL and the first direct evidence that the transition from the soluble state to surface-bound protein involves large conformational changes in the quaternary structure, thus highlighting the role of surface topography in immune recognition.