bluuebunny/crossref_metadata_2025 huggingface dataset:
Coordinated and Distinct Roles for IFN-αβ, IL-12, and IL-15 Regulation of NK Cell Responses to Viral Infection
Authors: Nguyen Khuong B. , Salazar-Mather Thais P. , Dalod Marc Y. , Van Deusen Jeffrey B. , Wei Xiao-qing , Liew Foo Y. , Caligiuri Michael A. , Durbin Joan E. , Biron Christine A.
Published: April 2014

NK cell cytotoxicity, IFN-γ expression, proliferation, and accumulation are rapidly induced after murine CMV infections. Under these conditions, the responses were shown to be elicited in overlapping populations. Nevertheless, there were distinct signaling molecule requirements for induction of functions within the subsets. IL-12/STAT4 was critical for NK cell IFN-γ expression, whereas IFN-αβ/STAT1 were required for induction of cytotoxicity. The accumulation/survival of proliferating NK cells was STAT4-independent but required IFN-αβ/STAT1 induction of IL-15. Taken together, the results define the coordinated interactions between the cytokines IFN-αβ, IL-12, and IL-15 for activation of protective NK cell responses during viral infections, and emphasize these factors’ nonredundant functions under in vivo physiological conditions.
Isotype Switching by Human B Cells Is Division-Associated and Regulated by Cytokines
Authors: Tangye Stuart G. , Ferguson Anthea , Avery Danielle T. , Ma Cindy S. , Hodgkin Philip D.
Published: April 2014

Isotype switching by murine B cells follows a pattern whereby the proportion of cells undergoing switching increases with division number and is regulated by cytokines. Here we explored whether human B cells behaved in a similar manner. The effect of IL-4, IL-10, and IL-13, alone or in combination, on Ig isotype switching by highly purified naive human CD40 ligand (CD40L)-activated B cells was measured against division number over various harvest times. Switching to IgG was induced by IL-4 and, to a lesser extent, IL-13 and IL-10. The combination of IL-10 with IL-4, but not IL-13, induced a higher percentage of cells to undergo switching. Isotype switching to IgG by human CD40L-activated naive B cells was found to be linked to the division history of the cells: IgG+ cells appeared in cultures of B cells stimulated with CD40L and IL-4 after approximately the third cell division, with the majority expressing IgG1, thus revealing a predictable pattern of IgG isotype switching. These results reveal a useful quantitative framework for monitoring the effects of cytokines on proliferation and isotype switching that should prove valuable for screening Ig immunodeficiencies and polymorphisms in the population for a better understanding of the regulation of human humoral immune responses.
P-, E-, and L-Selectin Mediate Migration of Activated CD8+ T Lymphocytes into Inflamed Skin
Authors: Hirata Takako , Furie Barbara C. , Furie Bruce
Published: April 2014

P- and E-selectin mediate CD4+ Th1 cell migration into the inflamed skin in a murine contact hypersensitivity model. In this model, not only CD4+ T cells but also CD8+ T cells infiltrate the inflamed skin, and the role of CD8+ type 1 cytotoxic T (Tc1) cells as effector cells has been demonstrated. Here we show that in mice deficient in both P- and E-selectin, the infiltration of CD8+ T cells in the inflamed skin is reduced, suggesting the role of these selectins in CD8+ T cell migration. We directly studied the role of selectins using in vitro-generated Tc1 cells. These cells are able to migrate into the inflamed skin of wild-type mice. This migration is partially mediated by P- and E-selectin, as shown by the reduced Tc1 cell migration into the inflamed skin of mice deficient in both P- and E-selectin or wild-type mice treated with the combination of anti-P-selectin and anti-E-selectin Abs. During P- and E-selectin-mediated migration of Tc1 cells, P-selectin glycoprotein ligand-1 appears to be the sole ligand for P-selectin and one of the ligands for E-selectin. P- and E-selectin-independent migration of Tc1 cells into the inflamed skin was predominantly mediated by L-selectin. These observations indicate that all three selectins can mediate Tc1 cell migration into the inflamed skin.
Human CD4 Expression at the Late Single-Positive Stage of Thymic Development Supports T Cell Maturation and Peripheral Export in CD4-Deficient Mice
Authors: Boyer Olivier , Marodon Gilles , Cohen José L. , Lejeune Laurence , Irinopoulou Théano , Liblau Roland , Bruneval Patrick , Klatzmann David
Published: April 2014

Positive selection of developing thymocytes is initiated at the double-positive (DP) CD4+CD8+ stage of their maturation. Accordingly, expression of a human CD4 (hCD4) transgene beginning at the DP stage has been shown to restore normal T cell development and function in CD4-deficient mice. However, it is unclear whether later onset CD4 expression would still allow such a restoration. To investigate this issue, we used transgenic mice in which a hCD4 transgene is not expressed on DP, but only on single-positive cells. By crossing these animals with CD4-deficient mice, we show that late hCD4 expression supports the maturation of T cell precursors and the peripheral export of mature TCRαβ+ CD8− T cells. These results were confirmed in two different MHC class II-restricted TCR transgenic mice. T cells arising by this process were functional in the periphery because they responded to agonist peptide in vivo. Interestingly, thymocytes of these mice appeared refractory to peptide-induced negative selection. Together, these results indicate that the effect of CD4 on positive selection of class II-restricted T cells extends surprisingly late into the maturation process by a previously unrecognized pathway of differentiation, which might contribute to the generation of autoreactive T cells.
Stromal Cells Provide the Matrix for Migration of Early Lymphoid Progenitors Through the Thymic Cortex
Authors: Prockop Susan E. , Palencia Sharina , Ryan Christina M. , Gordon Kristie , Gray Daniel , Petrie Howard T.
Published: April 2014

During steady state lymphopoiesis in the postnatal thymus, migration of precursors outward from the deep cortex toward the capsule is required for normal differentiation. Such migration requires, at a minimum, expression of adhesive receptors on the migrating lymphoid cells, as well as a stable matrix of their ligands persisting throughout the region of migration. In this study, we address the nature of this adhesive matrix. Although some precursor stages bound efficiently to extracellular matrix ligands, a specific requirement for the cell surface ligand VCAM-1 was also found. In situ analysis revealed that early precursors are found in intimate contact with a matrix formed by stromal cells in the cortex, a proportion of which expresses VCAM-1. In vivo administration of an anti-VCAM-1 Ab resulted in decreased thymic size and altered distribution of early precursors within the cortex. These results indicate that precursors migrating outward through the cortex may use a cellular, rather than extracellular, matrix for adhesion, and suggest that the VCAM-1+ subset of cortical stroma may play a crucial role in supporting the migration of early precursors in the steady state thymus.
Artiodactyl IgD: The Missing Link
Authors: Zhao Yaofeng , Kacskovics Imre , Pan Qiang , Liberles David A. , Geli Janos , Davis Scott K. , Rabbani Hodjattallah , Hammarstrom Lennart
Published: April 2014

IgD has been suggested to be a recently developed Ig class, only present in rodents and primates. However, in this paper the cow, sheep, and pig Ig δ genes have been identified and shown to be transcriptionally active. The deduced amino acid sequences from their cDNAs show that artiodactyl IgD H chains are structurally similar to human IgD, where the cow, sheep, and pig IgD H chain constant regions all contain three domains and a hinge region, sharing homologies of 43.6, 44, and 46.8% with their human counterpart, respectively. According to a phylogenetic analysis, the Cδ gene appears to have been duplicated from the Cμ gene >300 million yr ago. The ruminant μCH1 exon and its upstream region was again duplicated before the speciation of the cow and sheep, ∼20 million yr ago, inserted upstream of the δ gene hinge regions, and later modified by gene conversion. A short Sδ (switch δ) sequence resulting from the second duplication, is located immediately upstream of the bovine Cδ gene and directs regular μ-δ class switch recombination in the cow. The presence of Cδ genes in artiodactyls, possibly in most mammals, suggests that IgD may have some as yet unknown biological properties, distinct from those of IgM, conferring a survival advantage.
FcγR-Mediated Phagocytosis Stimulates Localized Pinocytosis in Human Neutrophils
Authors: Botelho Roberto J. , Tapper Hans , Furuya Wendy , Mojdami Donna , Grinstein Sergio
Published: April 2014

Engulfment of IgG-coated particles by neutrophils and macrophages is an essential component of the innate immune response. This process, known as phagocytosis, is triggered by clustering of FcγR at sites where leukocytes make contact with the opsonized particles. We found that phagocytosis is accompanied by a burst of fluid phase pinocytosis, which is largely restricted to the immediate vicinity of the phagosomal cup. FcγR-induced pinocytosis preceded and appeared to be independent of phagosomal sealing. Accordingly, fluid phase uptake was accentuated by actin depolymerization, which precludes phagocytosis. Stimulation of pinocytosis required phosphatidylinositol 3-kinase activity and was eliminated when changes in the cytosolic free Ca2+ concentration were prevented. Because stimulation of FcγR also induces secretion, which is similarly calcium and phosphatidylinositol 3-kinase dependent, we studied the possible relationship between these events. Neutrophil fragments devoid of secretory granules (cytoplasts) were prepared by sedimentation through Ficoll gradients. Cytoplasts could perform FcγR-mediated phagocytosis, which was not accompanied by activation of pinocytosis. This observation suggests that granule exocytosis is required for stimulation of pinocytosis. Analysis of the cytosolic Ca2+ dependence of secretion and pinocytosis suggests that primary (lysosomal) granule exocytosis is the main determinant of pinocytosis during FcγR stimulation. Importantly, primary granules are secreted in a polarized fashion near forming phagosomes. Focal pinocytosis during particle engulfment may contribute to Ag processing and presentation and/or to retrieval of components of the secretory machinery. Alternatively, it may represent an early event in the remodeling of the phagosomal membrane, leading to phagosomal maturation.
IFN-γ Production from Liver Mononuclear Cells of Mice in Burn Injury As Well As in Postburn Bacterial Infection Models and the Therapeutic Effect of IL-18
Authors: Ami Katsunori , Kinoshita Manabu , Yamauchi Akira , Nishikage Tetsuro , Habu Yoshiko , Shinomiya Nariyoshi , Iwai Takehisa , Hiraide Hoshio , Seki Shuhji
Published: April 2014

Hosts after severe burn injury are known to have a defect in the Th1 immune response and are susceptible to bacterial infections. We herein show that liver NK cells are potent IFN-γ producers early after burn injury. However, when mice were injected with LPS 24 h after burn injury, IFN-γ production from liver mononuclear cells (MNC; which we previously showed to be NK cells) was suppressed, and the serum IFN-γ concentration did not increase, while serum IL-10 conversely increased compared with control mice. Interestingly, a single injection of IL-18 simultaneously with LPS greatly restored the serum IFN-γ concentration in mice with burn injury and also increased IFN-γ production from liver MNC. Nevertheless, a single IL-18 injection into mice simultaneously with LPS was no longer effective in the restoration of serum IFN-γ and IFN-γ production from the liver MNC at 7 days after burn injury, when mice were considered to be the most immunocompromised. However, IL-18 injections into mice on alternate days beginning 1 day after burn injury strongly up-regulated LPS-induced serum IFN-γ levels and IFN-γ production from liver and spleen MNC of mice 7 days after burn injury and down-regulated serum IL-10. Furthermore, similar IL-18 therapy up-regulated serum IFN-γ levels in mice with experimental bacterial peritonitis 7 days after burn injury and greatly decreased mouse mortality. Thus, IL-18 therapy restores the Th1 response and may decrease the susceptibility to bacterial infection in mice with burn injury.
Retroviral Interference on STAT Activation in Individuals Coinfected with Human T Cell Leukemia Virus Type 2 and HIV-1
Authors: Bovolenta Chiara , Pilotti Elisabetta , Mauri Massimiliano , Panzeri Barbara , Sassi Monica , Dall’Aglio PierPaolo , Bertazzoni Umberto , Poli Guido , Casoli Claudio
Published: April 2014

Human T cell leukemia virus (HTLV) type-2 is a human retrovirus whose infection has not been tightly linked to human diseases. However, the fairly high prevalence of this infection among HIV-1-positive individuals indicates the importance of better understanding the potential interference of HTLV-2 infection on HIV-1 infection and AIDS. We previously demonstrated that one signature of PBMC freshly derived from HIV-1-infected individuals is the constitutive activation of a C-terminal truncated STAT5 (STAT5Δ). Therefore, we analyzed the potential activation of STATs in HTLV-2 monoinfected and HTLV-2/HIV-1 dually infected individuals. We observed that PBMC of HTLV-2-infected individuals do not show STAT activation unless they are cultivated ex vivo, in the absence of any mitogenic stimuli, for at least 8 h. The emergence of STAT activation, namely of STAT1, in culture was mostly related to the secretion of IFN-γ. Of note, this phenomenon is not only a characteristic feature of HTLV-2-infected individuals but also occurred with PBMC of HIV-1+ individuals. Surprisingly, HTLV-2/HIV-1 coinfection resulted in low/absent STAT activation in vivo that paralleled a diminished secretion of IFN-γ after ex vivo cultivation. Our findings indicate that both HTLV-2 and HIV-1 infection prime T lymphocytes for STAT1 activation, but they also highlight an interference exerted by HTLV-2 on HIV-1-induced STAT1 activation. Although the nature of such a phenomenon is unclear at the present, these findings support the hypothesis that HTLV-2 may interfere with HIV-1 infection at multiple levels.
The Innate Immune Response Differs in Primary and SecondarySalmonellaInfection
Authors: Kirby Alun C. , Yrlid Ulf , Wick Mary Jo
Published: April 2014

This study examines innate immunity to oral Salmonella during primary infection and after secondary challenge of immune mice. Splenic NK and NKT cells plummeted early after primary infection, while neutrophils and macrophages (Mφ) increased 10- and 3-fold, respectively. In contrast, immune animals had only a modest reduction in NK cells, no loss of NKT cells, and a slight increase in phagocytes following secondary challenge. During primary infection, the dominant sources of IFN-γ were, unexpectedly, neutrophils and Mφ, the former having intracellular stores of IFN-γ that were released during infection. IFN-γ-producing phagocytes greatly outnumbered IFN-γ-producing NK cells, NKT cells, and T cells during the primary response. TNF-α production was also dominated by neutrophils and Mφ, which vastly outnumbered NKT cells producing this cytokine. Neither T cells nor NK cells produced TNF-α early during primary infection. The TNF-α response was reduced in a secondary response, but remained dominated by neutrophils and Mφ. Moreover, no significant IFN-γ production by Mφ was associated with the secondary response. Indeed, only NK1.1+ cells and T cells produced IFN-γ in these mice. These studies provide a coherent view of innate immunity to oral Salmonella infection, reveal novel sources of IFN-γ, and demonstrate that immune status influences the nature of the innate response.
Synergistic Engagement of an Ineffective Endogenous Anti-Tumor Immune Response and Induction of IFN-γ and Fas-Ligand-Dependent Tumor Eradication by Combined Administration of IL-18 and IL-2
Authors: Wigginton Jon M. , Lee Jong-Keuk , Wiltrout Theresa A. , Alvord W. Gregory , Hixon Julie A. , Subleski Jeffrey , Back Timothy C. , Wiltrout Robert H.
Published: April 2014

IFN-γ is a critical component of the endogenous and many cytokine-induced antitumor immune responses. In this study we have shown that the combination of IL-18 and IL-2 (IL-18/IL-2) synergistically enhances IFN-γ production both in vitro and in vivo, and synergizes in vivo to induce complete durable regression of well-established 3LL tumors in >80% of treated mice. We have observed a nascent, but ineffective, host immune response against 3LL that depends on endogenous IFN-γ and IL-12 production and the Fas/Fas ligand (Fas-L) pathway. The combined administration of IL-18/IL-2 engages this endogenous response to induce tumor regression via a mechanism that is independent of NK and NKT cells or IL-12, but is critically dependent on CD8+ T cells, IFN-γ, and the Fas/Fas-L pathway. These studies demonstrate the importance of IFN-γ as well as the Fas/Fas-L pathway in both endogenous and cytokine-driven antitumor immune responses engaged by IL-18/IL-2 and provide preclinical impetus for clinical investigation of this potent anti-tumor combination.
Differential Requirement for NF-κB Family Members in Control of Helminth Infection and Intestinal Inflammation
Authors: Artis David , Shapira Sagi , Mason Nicola , Speirs Kendra M. , Goldschmidt Michael , Caamaño Jorge , Liou Hsiou-Chi , Hunter Christopher A. , Scott Phillip
Published: April 2014

The NF-κB family of transcription factors is critical in controlling the expression of a wide range of immune response genes. However, whether individual family members perform specific roles in regulating immunity and inflammation remains unclear. Here we investigated the requirement for NF-κB1, NF-κB2, and c-Rel in the expression of Th2 cytokine responses, development of host protective immunity, and regulation of intestinal inflammation following infection with the gut-dwelling helminth parasite Trichuris muris. While mice deficient in c-Rel mounted sufficient Th2 responses to expel infection, NF-κB1 knockout (KO) and NF-κB2 KO mice developed chronic infections associated with elevated production of Ag-specific IFN-γ. However, only infected NF-κB1 KO mice exhibited polarized IFN-γ responses associated with the loss of intestinal goblet cells and the development of destructive colitis-like pathology. Furthermore, blockade of IL-12 (previously shown to confer resistance in susceptible strains) recovered Ag-specific IL-13 responses and resistance to infection in NF-κB2 KO, but not NF-κB1 KO mice. Therefore, unique infection, immunological, and pathological outcomes were observed in different NF-κB KO strains. Taken together, these results provide direct evidence of nonoverlapping functions for NF-κB family members in the development of Th2 cytokine-mediated resistance to T. muris and the control of infection-induced intestinal inflammation.
The Mouse Model of Amebic Colitis Reveals Mouse Strain Susceptibility to Infection and Exacerbation of Disease by CD4+ T Cells
Authors: Houpt Eric R. , Glembocki David J. , Obrig Tom G. , Moskaluk Christopher A. , Lockhart Lauren A. , Wright Rhonda L. , Seaner Regina M. , Keepers Tiffany R. , Wilkins Tracy D. , Petri William A.
Published: April 2014

Amebic colitis is an important worldwide parasitic disease for which there is not a well-established animal model. In this work we show that intracecal inoculation of Entamoeba histolytica trophozoites led to established infection in 60% of C3H mice, while C57BL/6 or BALB/c mice were resistant, including mice genetically deficient for IL-12, IFN-γ, or inducible NO synthase. Infection was a chronic and nonhealing cecitis that pathologically mirrored human disease. Characterization of the inflammation by gene chip analysis revealed abundant mast cell activity. Parasite-specific Ab and cellular proliferative responses were robust and marked by IL-4 and IL-13 production. Depletion of CD4+ cells significantly diminished both parasite burden and inflammation and correlated with decreased IL-4 and IL-13 production and loss of mast cell infiltration. This model reveals important immune factors that influence susceptibility to infection and demonstrates for the first time the pathologic contribution of the host immune response in amebiasis.
Differences Between T Cell Epitopes Recognized After Immunization and After Infection
Authors: Vogel Thorsten U. , Horton Helen , Fuller Deborah H. , Carter Donald K. , Vielhuber Kathy , O’Connor David H. , Shipley Tim , Fuller Jim , Sutter Gerd , Erfle Volker , Wilson Nancy , Picker Louis J. , Watkins David I.
Published: April 2014

Evidence suggests that cellular immune responses play a crucial role in the control of HIV and SIV replication in infected individuals. Several vaccine strategies have therefore targeted these CD8+ and CD4+ responses. Whether vaccination induces the same repertoire of responses seen after infection is, however, a key unanswered question in HIV vaccine development. We therefore compared the epitope specificity induced by vaccination to that present postchallenge in the peripheral blood. Intracellular cytokine staining of PBMC stimulated with overlapping 15/20-mer peptides spanning the proteins of SIV were measured after DNA/modified vaccinia Ankara vaccination of eight rhesus macaques. Lymphocytes from 8 animals recognized a total of 39 CD8 epitopes and 41 CD4 epitopes encoded by the vaccine. T cell responses were again monitored after challenge with SIVmac239 to investigate the evolution of these responses. Only 57% of all CD8+ T cell responses and 19% of all CD4+ T cell responses present after vaccination were recalled after infection as measured in the peripheral blood. Interestingly, 29 new CD8 epitopes and 5 new CD4 epitopes were recognized by PBMC in the acute phase. These new epitopes were not detected after vaccination, and only some of them were maintained in the chronic phase (33% of CD8 and no CD4 responses). Additionally, 24 new CD8 epitopes and 7 new CD4 epitopes were recognized by PBMC in the chronic phase of infection. The repertoire of the immune response detected in the peripheral blood after immunization substantially differed from the immune response detected in the peripheral blood after infection.
Pseudomonas aeruginosaActivates Human Mast Cells to Induce Neutrophil Transendothelial Migration Via Mast Cell-Derived IL-1α and β
Authors: Lin Tong-Jun , Garduno Rafael , Boudreau Robert T. M. , Issekutz Andrew C.
Published: April 2014

The mechanisms of neutrophil (PMN) recruitment to Pseudomonas aeruginosa infection remain incompletely defined. Mast cells (MC) involvement in this process has not been studied previously. In this study, we demonstrate that human cord blood-derived MC phagocytose P. aeruginosa and release mediators that activate HUVEC monolayers for supporting PMN transmigration. Pretreatment of supernatants from P. aeruginosa-MC cocultures with neutralizing anti-IL-1α plus anti-IL-1β Abs, or IL-1R antagonist before addition to HUVEC for stimulation completely abrogated MC-induced PMN transmigration, while anti-TNF-α treatment had no effect. The expression of E-selectin and ICAM-1 on HUVEC, the latter a ligand for PMN CD11/CD18, was significantly up-regulated by P. aeruginosa-induced MC mediators. Pretreatment of human PMN with anti-CD18 mAb or pretreatment of HUVEC with a combination of three mAbs (against ICAM-1, ICAM-2, and E-selectin) inhibited by 85% the MC-dependent PMN transmigration. Moreover, P. aeruginosa-induced production of IL-1α and IL-1β was down-regulated by IL-10 and dexamethasone. This study demonstrates for the first time that MC may mediate P. aeruginosa-induced PMN recruitment via production of IL-1α and β. These findings have important implications for diseases involving P. aeruginosa infection and suggest novel targets for modulating P. aeruginosa-induced inflammation.
Leukocyte Rolling Velocities and Migration Are Optimized by Cooperative L-Selectin and Intercellular Adhesion Molecule-1 Functions
Authors: Kadono Takafumi , Venturi Guglielmo M. , Steeber Douglas A. , Tedder Thomas F.
Published: April 2014

Selectin family members largely mediate initial tethering and rolling of leukocytes on vascular endothelium, whereas integrin and Ig family members are essential for leukocyte firm adhesion. To quantify functional synergy between L-selectin and Ig family members during leukocyte rolling, the EA.hy926 human vascular endothelial line was transfected with either fucosyltransferase VII (926-FtVII) cDNA to generate L-selectin ligands alone or together with ICAM-1 cDNA (926-FtVII/ICAM-1). The ability of transfected 926 cells to support human leukocyte interactions was assessed in vitro using parallel plate flow chamber assays. Lymphocyte rolling on 926-FtVII cells was increased by ∼70% when ICAM-1 was expressed at physiological levels. Although initial tether formation was similar for both cell types, lymphocyte rolling was 26% slower on 926-FtVII/ICAM-1 cells. Pretreatment of lymphocytes with an anti-CD18 mAb eliminated the increase in rolling, and all rolling was blocked by anti-L-selectin mAb. In addition, rolling velocities of lymphocytes from CD18-hypomorphic mice were 48% faster on 926-FtVII/ICAM-1 cells, with a similar reduction in rolling frequency relative to wild-type lymphocytes. CD18-hypomorphic lymphocytes also showed an ∼40% decrease in migration to peripheral and mesenteric lymph nodes during in vivo migration assays compared with wild-type lymphocytes. Likewise, wild-type lymphocyte migration to peripheral lymph nodes was reduced by ∼50% in ICAM-1−/− recipient mice. Similar to human lymphocytes, human neutrophils showed enhanced rolling interactions on 926-FtVII/ICAM-1 cells, but also firmly adhered. Thus, in addition to mediating leukocyte firm adhesion, CD18 integrin/ICAM-1 interactions regulate leukocyte rolling velocities and thereby optimize L-selectin-mediated leukocyte rolling.
HIV-1 Envelope gp41 Peptides Promote Migration of Human FcεRI+ Cells and Inhibit IL-13 Synthesis Through Interaction with Formyl Peptide Receptors
Authors: de Paulis Amato , Florio Giovanni , Prevete Nella , Triggiani Massimo , Fiorentino Isabella , Genovese Arturo , Marone Gianni
Published: April 2014

We evaluated the effects of synthetic peptides (2017, 2019, 2020, 2021, 2023, 2027, 2029, 2030, 2031, and 2035) encompassing the structure of HIV-1MN envelope gp41 on both chemotaxis of human basophils and the release of preformed mediators (histamine) and of cytokines (IL-13). Peptides 2019 and 2021 were potent basophil chemoattractants, whereas the other peptides examined were ineffective. Preincubation of basophils with FMLP or gp41 2019 resulted in complete desensitization to a subsequent challenge with homologous stimulus. Incubation of basophils with low concentration (5 × 10−7 M) of FMLP, which binds with high affinity to N-formyl peptide receptor (FPR), but not to FPR-like 1, did not affect the chemotactic response to a heterologous stimulus (gp41 2019). In contrast, a high concentration (10−4 M) of FMLP, which binds also to FPR-like 1, significantly reduced the chemotactic response to gp41 2019. The FPR antagonist cyclosporin H inhibited chemotaxis induced by FMLP, but not by gp41 2019. None of these peptides singly induced the release of histamine or cytokines (IL-4 and IL-13) from basophils. However, low concentrations of peptides 2019 and 2021 (10−8–10−6 M) inhibited histamine release from basophils challenged with FMLP but not the secretion caused by anti-IgE and gp120. Preincubation of basophils with peptides 2019 and 2021 inhibited the expression of both IL-13 mRNA, and the FMLP-induced release of IL-13 from basophils. These data highlight the complexity of the interactions between viral and bacterial peptides with FPR subtypes on human basophils.
Receptors and Signaling Mechanisms Required for Prostaglandin E2-Mediated Regulation of Mast Cell Degranulation and IL-6 Production
Authors: Nguyen MyTrang , Solle Michael , Audoly Laurent P. , Tilley Stephen L. , Stock Jeffrey L. , McNeish John D. , Coffman Thomas M. , Dombrowicz David , Koller Beverly H.
Published: April 2014

Mast cells are implicated in the pathogenesis of a broad spectrum of immunological disorders. These cells release inflammatory mediators in response to a number of stimuli, including IgE-Ag complexes. The degranulation of mast cells is modified by PGs. To begin to delineate the pathway(s) used by PGs to regulate mast cell function, we examined bone marrow-derived mast cells (BMMC) cultured from mice deficient in the EP1, EP2, EP3, and EP4 receptors for PGE2. Although BMMCs express all four of these PGE2 receptors, potentiation of Ag-stimulated degranulation and IL-6 cytokine production by PGE2 is dependent on the EP3 receptor. Consistent with the coupling of this receptor to Gαi, PGE2 activation of the EP3 receptor leads to both inhibition of adenylate cyclase and increased intracellular Ca2+. The magnitude of increase in intracellular Ca2+ induced by EP3 activation is similar to that observed after activation of cells with IgE and Ag. Although PGE alone is not sufficient to initiate BMMC degranulation, stimulation of cells with PGE along with PMA induces degranulation. These actions are mediated by the EP3 receptor through signals involving Ca2+ mobilization and/or decreased cAMP levels. Accordingly, these studies identify PGE2/EP3 as a proinflammatory signaling pathway that promotes mast cell activation.
The Relationship Between Allergen-Induced Tissue Eosinophilia and Markers of Repair and Remodeling in Human Atopic Skin
Authors: Phipps Simon , Ying Sun , Wangoo Arun , Ong Yee-Ean , Levi-Schaffer Francesca , Kay A. Barry
Published: April 2014

Several in vitro studies suggest that eosinophils may play a role in fibrosis, remodeling, and repair processes associated with IgE-mediated hypersensitivity. However, the relationship in vivo, between allergen-induced tissue eosinophilia and markers of repair has yet to be established in human atopic subjects. Using the allergen-induced cutaneous late-phase reaction as a model of allergic inflammation, we have tested the hypothesis that eosinophil-derived TGF-β1 and IL-13 are temporarily associated with myofibroblast formation and deposition of tenascin and procollagen I. Biopsies were taken from atopic volunteers at 1, 3, 6, 24, 48, and 72 h after intradermal allergen challenge and were examined by immunohistochemistry. Following the peak of the late-phase reaction (6 h) there were persisting TGF-β1+ eosinophils, α-smooth muscle actin+ myofibroblasts, tenascin immunoreactivity, and procollagen-I+ cells 24–48 h postchallenge. Direct evidence of generation of repair markers was obtained by coculture of eosinophils and fibroblasts. This resulted in α-smooth muscle actin immunoreactivity that was inhibitable by neutralizing Abs to TGF-β as well as production of tenascin transcripts and protein product. TGF-β1 and IL-13 also induced tenascin expression. We conclude that TGF-β1 and IL-13, provided partially by eosinophils, contribute to repair and remodeling events in allergic inflammation in human atopic skin.
Membrane Attack Complex Contributes to Destruction of Vascular Integrity in Acute Lung Allograft Rejection
Authors: Nakashima Shinji , Qian Zhiping , Rahimi Salma , Wasowska Barbara A. , Baldwin William M.
Published: April 2014

The lung is known to be particularly susceptible to complement-mediated injury. Both C5a and the membrane attack complex (MAC), which is formed by the terminal components of complement (C5b-C9), can cause acute pulmonary distress in nontransplanted lungs. We used C6-deficient rats to investigate whether MAC causes injury to lung allografts. PVG.R8 lungs were transplanted orthotopically to MHC class I-incompatible PVG.1U recipients. Allografts from C6-sufficient (C6+) donors to C6+ recipients were rejected with an intense vascular infiltration and diffuse alveolar hemorrhage 7 days after transplantation (n = 5). Ab and complement (C3d) deposition was accompanied by extensive vascular endothelial injury and intravascular release of von Willebrand factor. In contrast, lung allografts from C6-deficient (C6−) donors to C6− recipients survived 13–17 days (n = 5). In the absence of C6, perivascular mononuclear infiltrates of ED1+ macrophages and CD8+ T lymphocytes were present 7 days after transplantation, but vascular endothelial cells were quiescent, with minimal von Willebrand factor release and no evidence of alveolar hemorrhage or edema. Lung allografts were performed from C6− donors to C6+ recipients (n = 5) and from C6+ donors to C6− recipients (n = 5) to separate the effects of systemic and local C6 production. Lungs transplanted from C6+ donors to C6− recipients had increased alveolar macrophages and capillary injury. C6 production by lung allografts was demonstrated at the mRNA and protein levels. These results demonstrate that MAC causes vascular injury in lung allografts and that the location of injury is dependent on the source of C6.
Constitutive OX40/OX40 Ligand Interaction Induces Autoimmune-Like Diseases
Authors: Murata Kazuko , Nose Masato , Ndhlovu Lishomwa C. , Sato Takayuki , Sugamura Kazuo , Ishii Naoto
Published: April 2014

The interaction between OX40 and OX40 ligand (OX40L) is suggested to provide T cells with an effective costimulatory signals during T cell-APC interaction. To examine the in vivo effect of constitutive OX40/OX40L interaction during immune regulation, we report the establishment of OX40L-transgenic (OX40L-Tg) mice that constitutively express OX40L on T cells. Markedly elevated numbers of effector memory CD4+ T cells, but not CD8+ T cells, were observed in the secondary lymphoid organs of OX40L-Tg mice. Upon immunization with keyhole limpet hemocyanin in the absence of adjuvant, profound T cell proliferative responses and cytokine productions were seen in the OX40L-Tg mice as compared with wild-type mice. Furthermore, in OX40L-Tg mice administrated with superantigen, this constitutive OX40/OX40L interaction on CD4+ T cells completely prevented normal in vivo clonal T cell deletion. Interestingly, OX40L-Tg mice on the C57BL/6 background spontaneously developed interstitial pneumonia and inflammatory bowel disease that was accompanied with a significant production of anti-DNA Ab in the sera. Surprisingly, these diseases were not evident on the OX40L-Tg mice on the BALB/c strain. However, such inflammatory diseases were successfully reproducible in recombination-activating gene (RAG)2-deficient mice upon transfer of OX40L-Tg CD4+ T cells. Blockade of OX40/OX40L interaction in the recipient RAG2-deficient mice completely prevented disease development. The present results orchestrated in this study indicate that OX40/OX40L interaction may be a vital link in our understanding of T cell-mediated organ-specific autoimmunity.
MHC Susceptibility Genes to IgA Deficiency Are Located in Different Regions on Different HLA Haplotypes
Authors: De la Concha Emilio G. , Fernandez-Arquero Miguel , Gual Lorena , Vigil Patricia , Martinez Alfonso , Urcelay Elena , Ferreira Antonio , Garcia-Rodriguez Maria C. , Fontan Gumersindo
Published: April 2014

Familial predisposition to IgA deficiency (IgAD) suggests that genetic factors influence susceptibility. Most studies support a polygenic inheritance with a susceptibility locus (designated IGAD1) in the MHC, but its exact location is still controversial. This study aimed to map the predisposing IGAD1 locus (or loci) within the MHC by investigating the pattern of association of the disease with several markers in the region. DNA-based techniques were used to type individual alleles of four polymorphic HLA genes (HLA-DR, -DQA1, -DQB1, and HLA-B), six microsatellites (all located between HLA-DR and HLA-B), and three single nucleotide polymorphisms on the TNF gene. The frequencies of these alleles were compared among ethnically matched populations comprising 182 patients and 343 controls. Additionally, we investigated parents and siblings of 100 of these patients. All four parental haplotypes were established in each family (n = 400), and transmission disequilibrium tests were performed. Surprisingly, our results did not support the hypothesis of a unique susceptibility gene being shared by all MHC susceptibility haplotypes. On HLA-DR1 and -DR7-positive haplotypes IGAD1 mapped to the class II region, whereas on haplotypes carrying HLA-DR3 the susceptibility locus mapped to the telomeric end of the class III region, as reported previously. Our results show how, in complex diseases, individuals may be affected for different genetic reasons and a single linkage signal to a region of a chromosome may actually be the result of disease-predisposing alleles in different linked genes in different pedigrees.
Helper-Dependent Adenoviral Vectors Efficiently Express Transgenes in Human Dendritic Cells but Still Stimulate Antiviral Immune Responses
Authors: Roth Michael D. , Cheng Qingwen , Harui Airi , Basak Saroj K. , Mitani Kohnosuke , Low Teresa A. , Kiertscher Sylvia M.
Published: April 2014

Adenoviral (AdV) vectors can be used to transduce a wide range of human cells and tissues. However, pre-existing immunity to AdV, and enhancement of this immunity after repeated administration, limits their clinical application. This may be especially relevant when vectors are loaded into APCs. Helper-dependent AdV (Hd-AdV), in which viral coding regions are replaced by human stuffer DNA, offers a new approach for limiting antiviral responses. To evaluate their immunogenicity, human dendritic cells (DCs) were infected with either an Hd-AdV or a conventional replication-deficient E1-deleted AdV (E1-AdV) and were evaluated for their capacity to stimulate antiviral T cell responses. Hd-AdV proved to be 50- to 275-fold more effective than E1-AdV at expressing the lacZ transgene in human DCs. PCR demonstrated similar transduction efficiencies, but RT-PCR revealed much higher expression of transgene mRNA after transduction with Hd-AdV. Functionally, DCs transduced with Hd-AdV stimulated the proliferation of autologous T cells to the same level as DCs transduced with E1-AdV. Identical viral-specific T cell responder frequencies were observed and T cells stimulated with either type of AdV-transduced DC lysed viral-infected target cells. Disrupting transcription of vector-based genes had no effect on T cell activation, suggesting that responses against both vectors were directed against preformed components of the viral capsid. We conclude that Hd-AdV vectors can be used to obtain higher transgene expression in human DCs but that they still evoke a vector-related immune response similar to that generated by E1-AdV.
Dynamics of T Cells and TCR Excision Circles Differ After Treatment of Acute and Chronic HIV Infection
Authors: Lewin Sharon R. , Ribeiro Ruy M. , Kaufmann Gilbert R. , Smith Don , Zaunders John , Law Matthew , Solomon Ajantha , Cameron Paul U. , Cooper David , Perelson Alan S.
Published: April 2014

We quantified T cell proliferation and thymic function in primary HIV infection (PHI; n = 19) and chronic HIV infection (CHI; n = 14) by measuring Ki67 staining and TCR excision circle (TREC) number. After antiretroviral therapy of PHI there is a profound decrease in the number and percentage of Ki67+ T cells (<6% Ki67+) with no significant increase in TREC per million cells and a transient increase in TREC per milliliter. In contrast, after antiretroviral therapy of CHI there is a reduction in the percentage but little change in the total number of Ki67+CD4+ T cells associated with increases in both TREC per million cells and TREC per milliliter. Using a mathematical model that accounts for proliferation, death, and redistribution of T cells, we find that redistribution is consistent with the TREC changes observed during treatment of PHI and that an increase in thymic output is needed to explain the increase in TREC during treatment of CHI. Consideration of TREC per milliliter shows that changes in proliferation alone cannot explain the changes in TREC. In addition, although increased proliferation of memory cells in HIV infection has been established, we find no difference in TREC per million CD45RA− “memory” T cells between healthy and infected individuals (p = 0.154 for CD4+; p = 0.383 for CD8+). Finally, although the number of TREC per million cells is always much lower in memory T cells than in naive T cells, in the setting of HIV infection, given that memory cells make up a larger proportion of total T cells, we find that 50% of TREC per milliliter in CD4+ T cells is harbored in the CD45RA− “memory” subset of our infected subjects.
Allograft Rejection by Primed/Memory CD8+ T Cells Is CD154 Blockade Resistant: Therapeutic Implications for Sensitized Transplant Recipients
Authors: Zhai Yuan , Meng Lingzhong , Gao Feng , Busuttil Ronald W. , Kupiec-Weglinski Jerzy W.
Published: April 2014

We have shown that CD8+ CTLs are the key mediators of accelerated rejection, and that CD8+ T cells represent the prime targets of CD154 blockade in sensitized mouse recipients of cardiac allografts. However, the current protocols require CD154 blockade at the time of sensitization, whereas delayed treatment fails to affect graft rejection in sensitized recipients. To elucidate the mechanisms of costimulation blockade-resistant rejection and to improve the efficacy of CD154-targeted therapy, we found that alloreactive CD8+ T cells were activated despite the CD154 blockade in sensitized hosts. Comparative CD8 T cell activation study in naive vs primed hosts has shown that although both naive and primed/memory CD8+ T cells relied on the CD28 costimulation for their activation, only naive, not primed/memory, CD8+ T cells depend on CD154 signaling to differentiate into CTL effector cells. Adjunctive therapy was designed accordingly to deplete primed/memory CD8+ T cells before the CD154 blockade. Indeed, unlike anti-CD154 monotherapy, transient depletion of CD8+ T cells around the time of cardiac engraftment significantly improved the efficacy of delayed CD154 blockade in sensitized hosts. Hence, this report provides evidence for 1) differential requirement of CD154 costimulation signals for naive vs primed/memory CD8+ T cells, and 2) successful treatment of clinically relevant sensitized recipients to achieve stable long term graft acceptance.
Cutting Edge: Impaired Toll-Like Receptor Expression and Function in Aging
Authors: Renshaw Mary , Rockwell Julie , Engleman Carrie , Gewirtz Andrew , Katz Jacqueline , Sambhara Suryaprakash
Published: April 2014

Toll-like receptors (TLR) are pattern recognition receptors that recognize conserved molecular patterns on microbes and link innate and adaptive immune systems. We investigated whether the enhanced susceptibility to bacterial, yeast, and viral infections and poor adaptive immune responses in aging are a result of diminished expression and function of TLRs. We examined the expression and function of all murine TLRs on macrophages from young and aged mice. Both splenic and activated peritoneal macrophages from aged mice expressed significantly lower levels of all TLRs. Furthermore, macrophages from aged mice secreted significantly lower levels of IL-6 and TNF-α when stimulated with known ligands for TLR1 and 2, 2 and 6,TLR3, TLR4, TLR5, and TLR9 when compared with those from young mice. These results support the concept that increased susceptibility to infections and poor adaptive immune responses in aging may be due to the decline in TLR expression and function.
Cutting Edge: CD4+CD25+ Regulatory T Cells Suppress Antigen-Specific Autoreactive Immune Responses and Central Nervous System Inflammation During Active Experimental Autoimmune Encephalomyelitis
Authors: Kohm Adam P. , Carpentier Pamela A. , Anger Holly A. , Miller Stephen D.
Published: April 2014

Autoreactive CD4+ T cells exist in normal individuals and retain the capacity to initiate autoimmune disease. The current study investigates the role of CD4+CD25+ T-regulatory (TR) cells during autoimmune disease using the CD4+ T cell-dependent myelin oligodendrocyte glycoprotein (MOG)-specific experimental autoimmune encephalomyelitis model of multiple sclerosis. In vitro, TR cells effectively inhibited both the proliferation of and cytokine production by MOG35–55-specific Th1 cells. In vivo, adoptive transfer of TR cells conferred significant protection from clinical experimental autoimmune encephalomyelitis which was associated with normal activation of autoreactive Th1 cells, but an increased frequency of MOG35–55-specific Th2 cells and decreased CNS infiltration. Lastly, transferred TR cells displayed an enhanced ability to traffic to the peripheral lymph nodes and expressed increased levels of the adhesion molecules ICAM-1 and P-selectin that may promote functional interactions with target T cells. Collectively, these findings suggest that TR cells contribute notably to the endogenous mechanisms that regulate actively induced autoimmune disease.
Most Murine CD8+ Intestinal Intraepithelial Lymphocytes Are Partially But Not Fully Activated T Cells
Authors: Wang Heuy-Ching , Zhou Qin , Dragoo Jolene , Klein John R.
Published: April 2014

Murine small intestine intraepithelial lymphocytes (IELs) bear properties of both activated and nonactivated T cells, although the significance of that dichotomy remains unclear. In this study, we show that although IELs express CD69 in situ and ex vivo, and have cytotoxic activity ex vivo, most CD8+ IELs from normal mice are phenotypically similar to naive T cells in that they are CD45RBhigh, CD44low/int, and lack or have low levels of expression of CD25, Ly-6C, OX40, Fas ligand (FasL), and intracellular IFN-γ synthesis. Unlike CD8+ lymph node cells, IELs express high levels of the FasL gene, but do not express surface FasL until after CD3-mediated stimulation has occurred. Additionally, anti-CD3 stimulation of IELs in the presence of actinomycin-D did not inhibit FasL expression, suggesting that regulation FasL expression on IELs is controlled at least partially at the posttranscriptional level. Following CD3-mediated stimulation, IELs synthesize and secrete IFN-γ more rapidly and to greater levels than CD8+ lymph node cells, and they acquire the phenotype of fully activated effector cells as seen by an up-regulation of CD44, Ly-6C, OX40, FasL, and CD25 with the kinetics of memory T cells, with down-regulation of CD45RB expression. These findings indicate that contrary to previous interpretations, most small intestine IELs are not fully activated T cells, but rather that they are semiactivated T cells ready to shift to a fully activated state once a CD3-mediated signal has been received. These data also imply that under appropriate conditions it is possible for T cells to be sustained in a state of partial activation.
T Cell Hyporesponsiveness Induced by Oral Administration of Ovalbumin Is Associated with Impaired NFAT Nuclear Translocation and p27kip1Degradation
Authors: Asai Kazumi , Hachimura Satoshi , Kimura Motoko , Toraya Terumasa , Yamashita Masakatsu , Nakayama Toshinori , Kaminogawa Shuichi
Published: April 2014

Oral tolerance is an important physiological component of the immune system whereby the organism avoids dangerous reactions such as hypersensitivity to ingested food proteins and other luminal Ags which may cause tissue damage and inflammation. In addition, it has been shown in animal models and in humans that oral tolerance can be applied to controlling undesired immune responses, including autoimmune diseases, allergies, and organ transplant rejections. However, the molecular mechanisms of oral tolerance have been poorly defined. In this study, we investigated the molecular basis underlying the hyporesponsiveness of orally tolerant CD4 T cells using a TCR transgenic mouse system in which oral tolerance was induced by long-term feeding with high dose Ag. We demonstrate that the hyporesponsive state of the CD4 T cells was maintained by a selective impairment in the TCR-induced calcium/NFAT signaling pathway and in the IL-2R-induced degradation of p27kip1 and cell cycle progression. Thus, physiological mucosal tolerance is revealed to be associated with a unique type of T cell hyporesponsiveness which differs from previously described anergic T cells.