bluuebunny/crossref_metadata_2025 huggingface dataset:
The Induction and Persistence of T Cell IFN-γ Responses after Vaccination or Natural Exposure Is Suppressed byPlasmodium falciparum
Authors: Bejon Philip , Mwacharo Jedidah , Kai Oscar , Todryk Stephen , Keating Sheila , Lowe Brett , Lang Trudie , Mwangi Tabitha W. , Gilbert Sarah C. , Peshu Norbert , Marsh Kevin , Hill Adrian V. S.
Published: April 2014

Epidemiological observations suggest that T cell immunity may be suppressed in malaria-endemic areas. In vitro studies, animal models, and limited data in humans link immunosuppression with malaria, malnutrition, and other parasitic infections. However, there are no data to determine whether malaria-induced immunosuppression is significant in the long-term, or relative data comparing it with other factors in malaria-endemic areas, so as to measure the impact of malaria, other parasitic disease, nutritional status, age. and location on the acquisition and longevity of IFN-γ responses in children in Kenya. We studied these factors in two cohorts of 1- to 6-year-old children in a malaria-endemic area. T cell responses were induced by vaccination in one cohort, and acquired as a result of natural exposure in a second cohort. Serial ELISPOT assays conducted over a 1-year period measured the induction and kinetics of IFN-γ production in response to the malaria Ag thrombospondin-related adhesion protein. Induced responses in both cohorts and the longevity of response in the vaccinated cohort were fitted to potential explanatory variables. Parasitemia was prospectively associated with reduced IFN-γ-producing T cells in both cohorts (by 15–25%), and both parasitemia and episodes of febrile malaria were associated with 19 and 31% greater attrition of T cell responses, respectively. Malaria may reduce the efficacy vaccinations such as bacillus Calmette-Guérin and investigational T cell-inducing vaccines, and may delay the acquisition of immunity following natural exposure to malaria and other pathogens.
CD45RB Ligation Inhibits Allergic Pulmonary Inflammation by Inducing CTLA4 Transcription
Authors: Jen Kai Yu , Campo Monica , He Hongzhen , Makani Samir S. , Velasco German , Rothstein David M. , Perkins David L. , Finn Patricia W.
Published: April 2014

CD45, a type I transmembrane protein tyrosine phosphatase expressed on nucleated hemopoietic cells, is prominently involved in T cell activation. Ligation of CD45RB isoforms has been associated with transplant tolerance. A recent genotyping analysis of asthma indicates a correlation with CD45 splicing. In this study, we administered an anti-CD45RB mAb (aCD45) in a murine model of allergic asthma and found that CD45RB ligation decreases allergic responses. aCD45 decreases allergen-induced pulmonary eosinophilia, bronchoalveolar lavage IL-13, IgE, and airway responses. Also, aCD45 increases the expression of CTLA4, a negative regulator of T cell activation. Furthermore, CD45RB signals no longer decrease allergic inflammation when CTLA4 is inhibited. These data support a role for CTLA4 in CD45RB-mediated inhibition of allergic inflammation. T cells and splenocytes stimulated with aCD45 exhibited increased CTLA4 levels, and analysis of CTLA4 promoter gene constructs identified a CD45RB-inducible regulatory region localized from −335 to –62 bp relative to the transcription start site. Together, these findings suggest that CD45RB signals mediate a novel role in the modulation of allergic inflammation, orchestrated by T cells through induction of CTLA4 transcription.
Postimmunization with IFN-γ-Secreting Glioma Cells Combined with the Inducible Nitric Oxide Synthase Inhibitor Mercaptoethylguanidine Prolongs Survival of Rats with Intracerebral Tumors
Authors: Badn Wiaam , Visse Edward , Darabi Anna , Smith Karin Enell , Salford Leif G. , Siesjö Peter
Published: April 2014

High-grade gliomas are one of the most aggressive human tumors with <1% of patients surviving 5 years after surgery. Immunotherapy could offer a possibility to eradicate remnant tumor cells after conventional therapy. Experimental immunotherapy can induce partial cure of established intracerebral tumors in several rodent models. One reason for the limited therapeutic effects could be immunosuppression induced by both the growing tumor and the induced immune reaction. NO has been implicated in tumor-derived immune suppression in tumor-bearing hosts, and unspecific inhibitors of NO synthase have been shown to boost antitumor immunity. In this study, we show that the inducible NO synthase (iNOS)-specific inhibitor mercaptoethylguanidine (MEG) superiorly enhanced lymphocyte reactivity after polyclonal stimulation compared with the iNOS-specific inhibitor l-NIL and the unspecific NO synthase inhibitor l-NAME. Both iNOS inhibitors increased the number and proliferation of T cells but not of B cells. When combined during postimmunization with IFN-γ-secreting N32 rat glioma cells of rats harboring intracerebral tumors, only MEG increased the cure rate. However, this was only achieved when MEG was administered after immunizations. These findings implicate that NO has both enhancing and suppressive effects after active immunotherapy.
Interaction between Transmembrane TNF and TNFR1/2 Mediates the Activation of Monocytes by Contact with T Cells
Authors: Rossol Manuela , Meusch Undine , Pierer Matthias , Kaltenhäuser Sylke , Häntzschel Holm , Hauschildt Sunna , Wagner Ulf
Published: April 2014

Monocytes and monocytic cells produce proinflammatory cytokines upon direct cell contact with activated T cells. In the autoimmune disease rheumatoid arthritis, the pivotal role of TNF-α implies that the interaction between transmembrane TNF-α (mTNF) and the TNF receptors (TNFR1 and TNFR2) might participate in the T cell contact-dependent activation of monocytes. Accordingly, treatment of rheumatoid arthritis by administration of a TNF-α-blocking Ab was found to significantly decrease TNF-α production by monocytes. Several lines of evidence indicated that signaling through TNFR1/2 and through mTNF (reverse signaling) is involved in TNF-α production by monocytes after T cell contact: 1) blocking mTNF on activated T cells leads to a significant reduction in TNF-α production; 2) down-regulation of TNFR1/2 on monocytes by transfection with small interfering RNA results in diminished TNF-α production; 3) blocking or down-regulating TNFR2 on activated T cells inhibits TNF-α production, indicating that mTNF on the monocyte surface mediates signaling; 4) ligation of mTNF on monocytes by surface TNFR2 transfected into resting T cells induces TNF-α production due to reverse signaling by mTNF; and 5) ligation of mTNF on monocytes by a soluble TNFR2:Ig receptor construct induces TNF-α production due to reverse signaling. In conclusion, we identified mTNF and TNFR1/2 as interaction partners contributing to TNF-α production in monocytes. Both pathways initiated by mTNF-TNFR interaction are likely to be inhibited by treatment with anti-TNF-α Abs.
Accelerated Telomere Erosion Is Associated with a Declining Immune Function of Caregivers of Alzheimer’s Disease Patients
Authors: Damjanovic Amanda K. , Yang Yinhua , Glaser Ronald , Kiecolt-Glaser Janice K. , Nguyen Huy , Laskowski Bryon , Zou Yixiao , Beversdorf David Q. , Weng Nan-ping
Published: April 2014

Caregivers of Alzheimer’s disease patients endure chronic stress associated with a decline of immune function. To assess the psychological and immunological changes of caregivers, we compared depressive symptoms, PBMC composition, in vitro activation-induced proliferation and cytokine production, and telomere length and telomerase activity of 82 individuals (41 caregivers and 41 age- and gender-matched controls). We found depressive symptoms were significantly higher in caregivers than in controls (p < 0.001). Correspondingly, caregivers had significantly lower T cell proliferation but higher production of immune-regulatory cytokines (TNF-α and IL-10) than controls in response to stimulation in vitro. We examined the impact of these changes on cellular replicative lifespan and found that caregivers had significantly shorter telomere lengths in PBMC than controls (6.2 and 6.4 kb, respectively, p < 0.05) with similar shortening in isolated T cells and monocytes and that this telomere attrition in caregivers was not due to an increase of shorter telomere possessing T cell subsets in PBMC. Finally, we showed that basal telomerase activity in PBMC and T cells was significantly higher in caregivers than in controls (p < 0.0001), pointing to an unsuccessful attempt of cells to compensate the excessive loss of telomeres in caregivers. These findings demonstrate that chronic stress is associated with altered T cell function and accelerated immune cell aging as suggested by excessive telomere loss.
Rituximab-CD20 Complexes Are Shaved from Z138 Mantle Cell Lymphoma Cells in Intravenous and Subcutaneous SCID Mouse Models
Authors: Li Yongli , Williams Michael E. , Cousar John B. , Pawluczkowycz Andrew W. , Lindorfer Margaret A. , Taylor Ronald P.
Published: April 2014

Infusion of standard-dose rituximab (RTX) in chronic lymphocytic leukemia (CLL) patients promotes rapid complement activation and deposition of C3 fragments on CLL B cells. However, immediately after RTX infusions, there is substantial loss (shaving) of CD20 from circulating malignant cells. Because shaving can compromise efficacies of anticancer immunotherapeutic mAbs, we investigated whether shaving occurs in SCID mouse models. Z138 cells, a B cell line derived from human mantle cell lymphoma, were infused i.v. or s.c. The i.v. model recapitulates findings we previously reported for therapeutic RTX in CLL: i.v. infused RTX rapidly binds to Z138 cells in lungs, and binding is accompanied by deposition of C3 fragments. However, within 1 h targeted cells lose bound RTX and CD20, and these shaved cells are still demonstrable 40 h after RTX infusion. Z138 cells grow in tumors at s.c. injection sites, and infusion of large amounts of RTX (0.50 mg on each of 4 days) leads to considerable loss of CD20 from these cells. Human i.v. Ig blocked shaving, suggesting that FcγRI on cells of the mononuclear phagocytic system promote shaving. Examination of frozen tumor sections from treated mice by immunofluorescence revealed large areas of B cells devoid of CD20, with CD20 intact in adjacent areas; it is likely that RTX had opsonized Z138 cells closest to capillaries, and these cells were shaved by monocyte/macrophages. The shaving reaction occurs in neoplastic B cells in tissue and in peripheral blood, and strategies to enhance therapeutic targeting and block shaving are under development.
Down-Modulation of CXCR3 Surface Expression and Function in CD8+ T Cells from Cutaneous T Cell Lymphoma Patients
Authors: Winter Dorian , Moser Julia , Kriehuber Ernst , Wiesner Christoph , Knobler Robert , Trautinger Franz , Bombosi Paula , Stingl Georg , Petzelbauer Peter , Rot Antal , Maurer Dieter
Published: April 2014

Viruses can escape destruction by the immune system by exploitation of the chemokine-chemokine receptor system. It is less established whether human cancers can adopt similar strategies to evade immunologic control. In this study, we show that advanced cutaneous T cell lymphoma (CTCL) is associated with selective and efficient inactivation of CXCR3-dependent T cell migration. Our studies demonstrate that this alteration is at least in part due to CXCR3 down-regulation in vivo by elevated serum levels of CXCR3 ligands. The T cell population most affected by this down-regulatory mechanism are CD8+ cytotoxic effector T cells. In CTCL patients, cytotoxic effector T cells have strongly reduced surface CXCR3 expression, accumulate in peripheral blood, but are virtually absent from CTCL tumor lesions, indicating an inability to extravasate into lymphoma tissue. CTCL-associated inactivation of effector cell recruitment may be a paradigmatic example of a new type of immune escape mechanisms shielding the neoplasm from a tumoricidal attack.
Massive Load of Functional Effector CD4+ and CD8+ T Cells against Cytomegalovirus in Very Old Subjects
Authors: Vescovini Rosanna , Biasini Claudia , Fagnoni Francesco F. , Telera Anna Rita , Zanlari Luca , Pedrazzoni Mario , Bucci Laura , Monti Daniela , Medici Maria Cristina , Chezzi Carlo , Franceschi Claudio , Sansoni Paolo
Published: April 2014

A progressive, systemic, and low-grade proinflammatory status is one of the major characteristics of immunosenescence. Emerging data suggest a possible contribution of CMV, known to chronically infect a large proportion of humans, lifelong from newborns to centenarians. To test this hypothesis, we evaluated functional T cell responses to two CMV immunogenic proteins, pp65 and IE-1, in 65 chronically infected subjects aged 25–100 years. PBMC were stimulated with mixtures of peptides spanning the entire sequence of both proteins, and Ag specificity and magnitude of intracellular IFN-γ- and TNF-α-positive cells were then analyzed within both CD4+ and CD8+ T cells. Results indicate that pp65 and, to a lesser extent, IE-1 constitute major Ags against which aged people target functionally efficient T cell effector responses with massive production of Th1 cytokines and exhibition of CD107a degranulation marker. As a result, the production of IFN-γ induced in T cells by both Ags was seven to eight times greater in very old than in young subjects. The comparative analysis of pp65-specific responses in these very long-term carriers revealed a reciprocal relationship between CD4+ and CD8+ producing IFN-γ in the same individuals. These results indicate that CMV represents an important pathogen responsible for a strong immune activation in human aging. Such a remarkable burden of effector CD4+ and CD8+ T cells may be necessary to protect the elderly from CMV endogenous reactivation, but can turn detrimental by giving a substantial contribution to the proinflammatory status that accompanies the main age-related diseases.
A New Class of Reverse Signaling Costimulators Belongs to the TNF Family
Authors: Sun Mingyi , Fink Pamela J.
Published: April 2014

Recent evidence shows that many molecules of the TNF family serve as counter-receptors, inducing costimulation through reverse signals in addition to delivering signals through their respective TNF receptors. In this review, we will discuss this new class of costimulators with a focus on the mechanism of costimulation transduced by reverse signaling through Fas ligand.
Copolymer-1 Induces Adaptive Immune Anti-inflammatory Glial and Neuroprotective Responses in a Murine Model of HIV-1 Encephalitis
Authors: Gorantla Santhi , Liu Jianou , Sneller Hannah , Dou Huanyu , Holguin Adelina , Smith Lynette , Ikezu Tsuneya , Volsky David J. , Poluektova Larisa , Gendelman Howard E.
Published: April 2014

Copolymer-1 (COP-1) elicits neuroprotective activities in a wide range of neurodegenerative disorders. This occurs, in part, by adaptive immune-mediated suppression of microglial inflammatory responses. Because HIV infection and immune activation of perivascular macrophages and microglia drive a metabolic encephalopathy, we reasoned that COP-1 could be developed as an adjunctive therapy for disease. To test this, we developed a novel animal model system that reflects HIV-1 encephalitis in rodents with both innate and adaptive arms of the immune system. Bone marrow-derived macrophages were infected with HIV-1/vesicular stomatitis-pseudotyped virus and stereotactically injected into the basal ganglia of syngeneic mice. HIV-1 pseudotyped with vesicular stomatitis virus envelope-infected bone marrow-derived macrophages induced significant neuroinflammation, including astrogliosis and microglial activation with subsequent neuronal damage. Importantly, COP-1 immunization reduced astro- and microgliosis while diminishing neurodegeneration. Hippocampal neurogenesis was, in part, restored. This paralleled reductions in proinflammatory cytokines, including TNF-α and IL-1β, and inducible NO synthase, and increases in brain-derived neurotrophic factor. Ingress of Foxp3- and IL-4-expressing lymphocytes into brains of COP-1-immunized animals was observed. We conclude that COP-1 may warrant therapeutic consideration for HIV-1-associated cognitive impairments.
Binding of Lymphoid Chemokines to Collagen IV That Accumulates in the Basal Lamina of High Endothelial Venules: Its Implications in Lymphocyte Trafficking
Authors: Yang Bo-Gie , Tanaka Toshiyuki , Jang Myoung Ho , Bai Zhongbin , Hayasaka Haruko , Miyasaka Masayuki
Published: April 2014

Certain lymphoid chemokines are selectively and constitutively expressed in the high endothelial venules (HEV) of lymph nodes and Peyer’s patches, where they play critical roles in the directional migration of extravasating lymphocytes into the lymphoid tissue parenchyma. How these chemokines are selectively localized and act in situ, however, remains unclear. In the present study, we examined the possibility that basal lamina-associated extracellular matrix proteins in the HEVs are responsible for retaining the lymphoid chemokines locally. Here we show that collagen IV (Col IV) bound certain lymphoid chemokines, including CCL21, CXCL13, and CXCL12, more potently than did fibronectin or laminin-1, but it bound CCL19 and CCL5 only weakly, if at all. Surface plasmon resonance analysis indicated that Col IV bound CCL21 with a low nanomolar KD, which required the C-terminal region of CCL21. Col IV can apparently hold these chemokines in their active form upon binding, because the Col IV-bound chemokines induced lymphocyte migration efficiently in vitro. We found by immunohistochemistry that Col IV and CCL21, CXCL13, and CXCL12 were colocalized in the basal lamina of HEVs. When injected s.c. into plt/plt mice, CCL21 colocalized at least partially with Col IV on the basal lamina of HEVs in draining lymph nodes. Collectively, our results suggest that Col IV contributes to the creation of a lymphoid chemokine-rich environment in the basal lamina of HEVs by binding an array of locally produced lymphoid chemokines that promote directional lymphocyte trafficking from HEVs into the lymphoid tissue parenchyma.
Normal Establishment of Virus-Specific Memory CD8 T Cell Pool following Primary Infection during Pregnancy
Authors: Constantin Carolyn M. , Masopust David , Gourley Tania , Grayson Jason , Strickland Ora L. , Ahmed Rafi , Bonney Elizabeth A.
Published: April 2014

Suppression of cell-mediated immunity has been proposed as a mechanism that promotes maternal tolerance of the fetus but also contributes to increased occurrence and severity of certain infections during pregnancy. Despite decades of research examining the effect of pregnancy on Ag-specific T cell responses, many questions remain. In particular, quantitative examination of memory CD8 T cell generation following infection during pregnancy remains largely unknown. To examine this issue, we evaluated the generation of protective immunity following infection during pregnancy with a nonpersistent strain of lymphocytic choriomeningitis virus (LCMV) in mice. The CD8 T cell response to LCMV occurred normally in pregnant mice compared with the nonpregnant cohort with rapid viral clearance in all tissues tested except for the placenta. Despite significant infiltration of CD8 T cells to the maternal-fetal interface, virus persisted in the placenta until delivery. Live pups were not infected and generated normal primary immune responses when challenged as adults. Memory CD8 T cell development in mice that were pregnant during primary infection was normal with regards to the proliferative capacity, number of Ag-specific cells, cytokine production upon re-stimulation, and the ability to protect from re-infection. These data suggest that virus-specific adaptive memory is normally generated in mice during pregnancy.
Human Effector Memory CD4+ T Cells Directly Recognize Allogeneic Endothelial Cells In Vitro and In Vivo
Authors: Shiao Stephen L. , Kirkiles-Smith Nancy C. , Shepherd Benjamin R. , McNiff Jennifer M. , Carr Edward J. , Pober Jordan S.
Published: April 2014

The frequency of circulating alloreactive human memory T cells correlates with allograft rejection. Memory T cells may be divided into effector memory (TEM) and central memory (TCM) cell subsets, but their specific roles in allograft rejection are unknown. We report that CD4+ TEM (CD45RO+CCR7−CD62L−) can be adoptively transferred readily into C.B-17 SCID/bg mice and mediate the destruction of human endothelial cells (EC) in vascularized human skin grafts allogeneic to the T cell donor. In contrast, CD4+ TCM (CD45RO+CCR7+CD62L+) are inefficiently transferred and do not mediate EC injury. In vitro, CD4+ TEM secrete more IFN-γ within 48 h in response to allogeneic ECs than do TCM. In contrast, TEM and TCM secrete comparable amounts of IFN-γ in response to allogeneic monocytes (Mo). In the same cultures, both TEM and TCM produce IL-2 and proliferate in response to IFN-γ-treated allogeneic human EC or Mo, but TCM respond more vigorously in both assays. Blockade of LFA-3 strongly inhibits both IL-2 and IFN-γ secretion by CD4+ TEM cultured with allogeneic EC but only minimally inhibits responses to allogeneic Mo. Blockade of CD80 and CD86 strongly inhibits IL-2 but not IFN-γ production by in response to allogeneic EC or Mo. Transduction of EC to express B7-2 enhances allogeneic TEM production of IL-2 but not IFN-γ. We conclude that human CD4+ TEM directly recognize and respond to allogeneic EC in vitro by secreting IFN-γ and that this response depends on CD2 but not CD28. Consistent with EC activation of effector functions, human CD4+ TEM can mediate allogeneic EC injury in vivo.
The Transcription Factor Zbtb7b Promotes CD4 Expression by Antagonizing Runx-Mediated Activation of the CD4 Silencer
Authors: Wildt Kathryn F. , Sun Guangping , Grueter Baerbel , Fischer Maria , Zamisch Monica , Ehlers Marc , Bosselut Rémy
Published: April 2014

The persistence of CD4 expression is a key event distinguishing the differentiation of MHC class II-restricted thymocytes into CD4 T cells from that of MHC class I-restricted thymocytes into CD8 T cells. The zinc finger transcription factor Zbtb7b (or cKrox or Thpok) is normally expressed in MHC class II-restricted thymocytes and promotes CD4 lineage choice. When expressed in MHC class I-restricted cells, Zbtb7b redirects these cells from their normal CD8 fate to CD4 differentiation, implying that it promotes, directly or not, sustained CD4 expression; the present study has investigated the mechanism of this effect. We demonstrate that, although Zbtb7b does not enhance CD4 expression on its own, it antagonizes the CD4 repression mediated by the transcription factor Runx3, which is normally up-regulated during CD8 differentiation and promotes CD4 silencing. Zbtb7b also antagonizes CD4 repression by the related protein Runx1, which is expressed in CD4 lineage cells. This antagonism is observed both in vitro and in vivo, is transcriptional, and requires domains of Zbtb7b that are essential to its ability to promote CD4 differentiation in vivo. Furthermore, Zbtb7b fails to antagonize Runx in cells treated with histone deacetylase inhibitors, suggesting that Zbtb7b acts by reducing the expression of thus far unknown factors that cooperate with Runx molecules to repress CD4. These findings demonstrate that the transcription factor Zbtb7b promotes CD4 expression by antagonizing Runx-mediated CD4 repression.
IL-27 Suppresses Th2 Cell Development and Th2 Cytokines Production from Polarized Th2 Cells: A Novel Therapeutic Way for Th2-Mediated Allergic Inflammation
Authors: Yoshimoto Tomohiro , Yoshimoto Takayuki , Yasuda Koubun , Mizuguchi Junichiro , Nakanishi Kenji
Published: April 2014

IL-27 up-regulates Th1 but down-regulates Th2 responses. However, its molecular mechanism and regulatory effects on polarized Th2 cells remain unclear. In this study, we have revealed that IL-27 inhibits Th2 cell development as well as Th2 cytokines production from already polarized Th2 cells by down-regulation of GATA-3 and up-regulation of T-bet expression simultaneously. In vivo daily IL-27 treatment for 1 wk after Leishmania major infection protects BALB/c mice from footpad swelling by diminishing parasite burden via reciprocal regulation of Th1 and Th2 responses. Furthermore, IL-27 stimulation causes marked reduction in the capacity of host mouse to mount a Th2 response against Strongyloides venezuelensis infection. Thus, IL-27-treated mice failed to develop intestinal mastocytosis after S. venezuelensis infection and exhibited a marked delay in parasite expulsion. Finally, intranasal administration of IL-27 inhibits OVA-induced airway hyperresponsiveness and inflammation in OVA-sensitized animals. Thus, IL-27 could provide us with a novel therapeutic way for treating Th2-associated diseases such as bronchial asthma.
Intercellular Transfer of Carcinoembryonic Antigen from Tumor Cells to NK Cells
Authors: Stern-Ginossar Noam , Nedvetzki Shlomo , Markel Gal , Gazit Roi , Betser-Cohen Gili , Achdout Hagit , Aker Memet , Blumberg Richard S. , Davis Daniel M. , Appelmelk Ben , Mandelboim Ofer
Published: April 2014

The inhibition of NK cell killing is mainly mediated via the interaction of NK inhibitory receptors with MHC class I proteins. In addition, we have previously demonstrated that NK cells are inhibited in a class I MHC-independent manner via homophilic carcinoembryonic Ag (CEA) cell adhesion molecules (CEACAM1)-CEACAM1 and heterophilic CEACAM1-CEA interactions. However, the cross-talk between immune effector cells and their target cells is not limited to cell interactions per se, but also involves a specific exchange of proteins. The reasons for these molecular exchanges and the functional outcome of this phenomenon are still mostly unknown. In this study, we show that NK cells rapidly and specifically acquire CEA molecules from target cells. We evaluated the role of cytotoxicity in the acquisition of CEA and demonstrated it to be mostly killing independent. We further demonstrate that CEA transfer requires a specific interaction with an unknown putative NK cell receptor and that carbohydrates are probably involved in CEA recognition and acquisition by NK cells. Functionally, the killing of bulk NK cultures was inhibited by CEA-expressing cells, suggesting that this putative receptor is an inhibitory receptor.
Surfactant Protein A Activation of Atypical Protein Kinase C ζ in IκB-α-Dependent Anti-Inflammatory Immune Regulation
Authors: Moulakakis Christina , Adam Stefanie , Seitzer Ulrike , Schromm Andra B. , Leitges Michael , Stamme Cordula
Published: April 2014

The pulmonary collectin surfactant protein (SP)-A has a pivotal role in anti-inflammatory modulation of lung immunity. The mechanisms underlying SP-A-mediated inhibition of LPS-induced NF-κB activation in vivo and in vitro are only partially understood. We previously demonstrated that SP-A stabilizes IκB-α, the primary regulator of NF-κB, in alveolar macrophages (AM) both constitutively and in the presence of LPS. In this study, we show that in AM and PBMC from IκB-α knockout/IκB-β knockin mice, SP-A fails to inhibit LPS-induced TNF-α production and p65 nuclear translocation, confirming a critical role for IκB-α in SP-A-mediated LPS inhibition. We identify atypical (a) protein kinase C (PKC) ζ as a pivotal upstream regulator of SP-A-mediated IκB-α/NF-κB pathway modulation deduced from blocking experiments and confirmed by using AM from PKCζ−/− mice. SP-A transiently triggers aPKCThr410/403 phosphorylation, aPKC kinase activity, and translocation in primary rat AM. Coimmunoprecipitation experiments reveal that SP-A induces aPKC/p65 binding under constitutive conditions. Together the data indicate that anti-inflammatory macrophage activation via IκB-α by SP-A critically depends on PKCζ activity, and thus attribute a novel, stimulus-specific signaling function to PKCζ in SP-A-modulated pulmonary immune response.
T Regulatory Cells Control Numbers of NK Cells and CD8α+ Immature Dendritic Cells in the Lymph Node Paracortex
Authors: Giroux Martin , Yurchenko Ekaterina , St.-Pierre Jessica , Piccirillo Ciriaco A. , Perreault Claude
Published: April 2014

The spleen contains numerous NK cells whose differentiation profile is characterized by a preponderance of mature elements located mainly in the red pulp. In contrast, lymph nodes (LNs) contain few NK cells and they are sited mostly in T cell zones and skewed toward immature developmental stages. We show that, in mice, naturally occurring CD4+Foxp3+ regulatory T (Treg) cells are both necessary and sufficient to repress accumulation of NK cells in resting LNs. Moreover, we present evidence that Treg cells hamper generation of mature NK cells through short-range interactions with NK precursors. In turn, mature NK cells specifically regulate the amount of CD8α+ phenotypically immature dendritic cells present in LN T cell zones. We propose that the dominant influence of Treg cells on NK cell precursors and CD8α+ immature dendritic cells explains why “quiescent” LNs in the absence of infection function as privileged sites for induction and maintenance of tolerance to peripheral Ags.
EAE Tolerance Induction with Hsp70-Peptide Complexes Depends on H60 and NKG2D Activity
Authors: Galazka Grazyna , Jurewicz Anna , Orlowski Wojciech , Stasiolek Mariusz , Brosnan Celia F. , Raine Cedric S. , Selmaj Krzysztof
Published: April 2014

Inflammation leads to induction of tissue stress conditions that might contribute to the generation of mechanisms limiting ongoing immune responses. We have shown previously that peptides derived from brain tissue of mice with experimental autoimmune encephalomyelitis (EAE) complexed with the chaperone heat shock protein 70 (Hsp70-pc) induce an NK-cell-dependent tolerance for subsequent EAE sensitization. We now present data that showed that the MHC class I-related glycoprotein H60 determines Hsp70-pc-induced EAE inhibition. Hsp70-pc led to significant and selective up-regulation of H60 expression in SJL/J mice, and Ab-blocking of H60 expression led to loss of EAE tolerance. Similarly, blocking of the NK cell receptor for H60, NKG2D, also reversed the Hsp70-pc-induced EAE inhibition. In contrast, in C57BL/6 mice H60 was not expressed, and Hsp70-pc-induced tolerance was not detected. The NK cell mediated Hsp70-pc-induced tolerance to EAE was dependent on modulation of dendritic cells function leading to diminished T cell reactivity to PLP. As, no increase of H60 expression on T cells from EAE mice immunized with PLP was detected, and no enhanced loss of CD3+H60+over CD3+H60− cells in Hsp70-pc-induced EAE tolerance was found direct killing of H60+ PLP-reactive cells seems not to be involved in the Hsp70-pc-induced tolerance induction. We have provided evidence that Hsp70-pc-induced tolerance for EAE, mediated by NK cells, involves induction of H60 ligand and its interaction with NKG2D receptor. NK cells tolerization of EAE depends on altered dendritic cells activity leading to enhanced death of Ag reactive cells.
Pathogen-Specific CD8 T Cell Responses Are Directly Inhibited by IL-10
Authors: Biswas Partha Sarathi , Pedicord Virginia , Ploss Alexander , Menet Ewa , Leiner Ingrid , Pamer Eric G.
Published: April 2014

Regulation of CD8 T cell expansion and contraction is essential for successful immune defense against intracellular pathogens. IL-10 is a regulatory cytokine that can restrict T cell responses by inhibiting APC functions. IL-10, however, can also have direct effects on T cells. Although blockade or genetic deletion of IL-10 enhances T cell-mediated resistance to infections, the extent to which IL-10 limits in vivo APC function or T cell activation/proliferation remains unknown. Herein, we demonstrate that primary and memory CD8 T cell responses following Listeria monocytogenes infection are enhanced by the absence of IL-10. Surface expression of the IL-10R is transiently up-regulated on CD8 T cells following activation, suggesting that activated T cells can respond to IL-10 directly. Consistent with this notion, CD8 T cells lacking IL-10R2 underwent greater expansion than wild-type T cells upon L. monocytogenes infection. The absence of IL-10R2 on APCs, in contrast, did not enhance T cell responses following infection. Our studies demonstrate that IL-10 produced during bacterial infection directly limits expansion of pathogen-specific CD8 T cells and reveal an extrinsic regulatory mechanism that modulates the magnitude of memory T cell responses.
Skin-Derived Dendritic Cells Can Mediate Deletional Tolerance of Class I-Restricted Self-Reactive T Cells
Authors: Waithman Jason , Allan Rhys S. , Kosaka Hiroshi , Azukizawa Hiroaki , Shortman Ken , Lutz Manfred B. , Heath William R. , Carbone Francis R. , Belz Gabrielle T.
Published: April 2014

Skin-draining lymph nodes contain a number of dendritic cell (DC) subsets of different origins. Some of these are migratory, such as the skin-derived epidermal Langerhans cells and a separate dermal DC subset, whereas others are lymphoid resident in nature, such as the CD8+ DCs found throughout the lymphoid tissues. In this study, we examine the DC subset presentation of skin-derived self-Ag by migratory and lymphoid-resident DCs, both in the steady state and under conditions of local skin infection. We show that presentation of self-Ag is confined to skin-derived migrating DCs in both settings. Steady state presentation resulted in deletional T cell tolerance despite these DCs expressing a relatively mature phenotype as measured by traditional markers such as the level of MHC class II and CD86 expression. Thus, self-Ag can be carried to the draining lymph nodes by skin-derived DCs and there presented by these same cells for tolerization of the circulating T cell pool.
IFN-ε Mediates TNF-α-Induced STAT1 Phosphorylation and Induction of Retinoic Acid-Inducible Gene-I in Human Cervical Cancer Cells
Authors: Matsumiya Tomoh , Prescott Stephen M. , Stafforini Diana M.
Published: April 2014

Retinoic acid inducible gene-I (RIG-I) plays important roles during innate immune responses to viral infections and as a transducer of cytokine signaling. The mechanisms of RIG-I up-regulation after cytokine stimulation are incompletely characterized. It was previously reported that IFN–γ induces the expression of RIG-I in endothelial cells. In this study, we characterized the mechanism of type I IFN-mediated up-regulation of RIG-I in HeLa cells and found that, in addition to type I IFN, TNF-α, a cytokine that regulates innate immune responses, induced expression of RIG-I. To investigate whether TNF-α- and type I IFN-mediated up-regulations of RIG-I were causally related, we studied the kinetics of these responses. Our results were consistent with a model in which TNF-α functioned upstream of type I IFNs. The ability of TNF-α to up-regulate RIG-I required protein synthesis, expression of functional type I IFNRs, and STAT1 signaling. We also found that IFN-ε was the only IFN isoform expressed constitutively in HeLa cells and that its expression was up-regulated in response to stimulation with TNF-α. The mechanism of up-regulation involved stabilization of IFN-ε mRNA in the absence of transcriptional activation. Silencing the expression of IFN-ε attenuated STAT1 expression and phosphorylation and inhibited RIG-I expression, providing additional support for the participation of IFN-ε upstream of STAT1. Our findings support a sequential mechanism whereby TNF-α leads to stabilization of IFN-ε mRNA, increased IFN-ε synthesis, engagement of type I IFNRs, increased STAT1 expression and phosphorylation, and up-regulation of RIG-I expression. These findings have implications for our understanding of the immune responses that follow cytokine stimulation.
CD83 Expression Is a Sensitive Marker of Activation Required for B Cell and CD4+ T Cell Longevity In Vivo
Authors: Prazma Charlene M. , Yazawa Norihito , Fujimoto Yoko , Fujimoto Manabu , Tedder Thomas F.
Published: April 2014

CD83 is a surface marker that differentiates immature and mature human dendritic cell populations. Thymic epithelial cell expression of CD83 is also necessary for efficient CD4+ T cell development in mice. The altered phenotypes of peripheral B and CD4+ T cells, and the reduction of peripheral CD4+ T cells in CD83−/− mice, suggest additional functions for CD83. To assess this, a panel of mAbs was generated to characterize mouse CD83 expression by peripheral leukocytes. As in humans, activation of conventional and plasmacytoid murine dendritic cell subsets led to rapid up-regulation of CD83 surface expression in mice. In primary and secondary lymphoid compartments, a subset of B cells expressed low-level CD83, while CD83 was not detected on resting T cells. However, CD83 was prominently up-regulated on the majority of spleen B and T cells within hours of activation in vitro. In vivo, a low dose of hen egg lysozyme (1 μg) induced significant CD83 but not CD69 expression by Ag-specific B cells within 4 h of Ag challenge. Although B cell development appeared normal in CD83−/− mice, B and CD4+ T cell expression of CD83 was required for lymphocyte longevity in adoptive transfer experiments. Thus, the restricted expression pattern of CD83, its rapid induction following B cell and T cell activation, and its requirement for B cell and CD4+ T cell longevity demonstrate that CD83 is a functionally significant and sensitive marker of early lymphocyte activation in vivo.
Characterization of the Functional Properties of the Voltage-Gated Potassium Channel Kv1.3 in Human CD4+ T Lymphocytes
Authors: Hu Lina , Pennington Michael , Jiang Qiong , Whartenby Katharine A. , Calabresi Peter A.
Published: April 2014

Previous studies have shown that central memory T (TCM) cells predominantly use the calcium-dependent potassium channel KCa3.1 during acute activation, whereas effector memory T (TEM) cells use the voltage-gated potassium channel Kv1.3. Because Kv1.3-specific pharmacological blockade selectively inhibited anti-CD3-mediated proliferation, whereas naive T cells and TCM cells escaped inhibition due to up-regulation of KCa3.1, this difference indicated a potential for selective targeting of the TEM population. We examined the effects of pharmacological Kv1.3 blockers and a dominant-negative Kv1.x construct on T cell subsets to assess the specific effects of Kv1.3 blockade. Our studies indicated both TCM and TEM CD4+ T cells stimulated with anti-CD3 were inhibited by charybdotoxin, which can block both KCa3.1 and Kv1.3, whereas margatoxin and Stichodactyla helianthus toxin, which are more selective Kv1.3 inhibitors, inhibited proliferation and IFN-γ production only in the TEM subset. The addition of anti-CD28 enhanced proliferation of freshly isolated cells and rendered them refractory to S. helianthus, whereas chronically activated TEM cell lines appeared to be costimulation independent because Kv1.3 blockers effectively inhibited proliferation and IFN-γ regardless of second signal. Transduction of CD4+ T cells with dominant-negative Kv1.x led to a higher expression of CCR7+ TCM phenotype and a corresponding depletion of TEM. These data provide further support for Kv1.3 as a selective target of chronically activated TEM without compromising naive or TCM immune functions. Specific Kv1.3 blockers may be beneficial in autoimmune diseases such as multiple sclerosis in which TEM are found in the target organ.
Killing Kinetics of Simian Immunodeficiency Virus-Specific CD8+ T Cells: Implications for HIV Vaccine Strategies
Authors: Rollman Erik , Smith Miranda Z. , Brooks Andrew G. , Purcell Damian F. J. , Zuber Bartek , Ramshaw Ian A. , Kent Stephen J.
Published: April 2014

Both the magnitude and function of vaccine-induced HIV-specific CD8+ CTLs are likely to be important in the outcome of infection. We hypothesized that rapid cytolysis by CTLs may facilitate control of viral challenge. Release kinetics of the cytolytic effector molecules granzyme B and perforin, as well as the expression of the degranulation marker CD107a and IFN-γ were simultaneously studied in SIV Gag164–172 KP9-specific CD8+ T cells from Mane-A*10+ pigtail macaques. Macaques were vaccinated with either prime-boost poxvirus vector vaccines or live-attenuated SIV vaccines. Prime-boost vaccination induced Gag-specific CTLs capable of only slow (after 3 h) production of IFN-γ and with limited (<5%) degranulation and granzyme B release. Vaccination with live-attenuated SIV resulted in a rapid cytolytic profile of SIV-specific CTLs with rapid (<0.5 h) and robust (>50% of tetramer-positive CD8+ T cells) degranulation and granzyme B release. The cytolytic phenotype following live-attenuated SIV vaccinations were similar to that associated with the partial resolution of viremia following SIVmac251 challenge of prime-boost-vaccinated macaques, albeit with less IFN-γ expression. High proportions of KP9-specific T cells expressed the costimulatory molecule CD28 when they exhibited a rapid cytolytic phenotype. The delayed cytolytic phenotype exhibited by standard vector-based vaccine-induced CTLs may limit the ability of T cell-based HIV vaccines to rapidly control acute infection following a pathogenic lentiviral exposure.
Phosphatidylinositol 3-Kinase/Akt Activation by Integrin-Tumor Matrix Interaction Suppresses Fas-Mediated Apoptosis in T Cells
Authors: Su Chung-Chen , Lin Yu-Ping , Cheng Yu-Jung , Huang Jyun-Yuan , Chuang Woei-Jer , Shan Yan-Shen , Yang Bei-Chang
Published: April 2014

It has recently become apparent that the microenvironment made up of the extracellular matrix may affect cell signaling. In this study, we evaluated Fas-triggered apoptosis in T cells in contact with tumor cells, which resembles the cell-to-cell interactions found in tumor regions. Jurkat cells were less susceptible to the Fas-mediated apoptosis when cocultured with U118, HeLa, A549, and Huh-7 tumor cells. This was indicated by less plasma membrane alteration, an amelioration of the loss of mitochondria membrane potential, a decrease in caspase-8 and caspase-3 activation, a decrease in DNA fragmentation factor-45/35 cleavage, and a reduction in the breakage of DNA when compared with Jurkat cells cultured alone. In contrast, the tumor cell lines MCF-7 and HepG2 produced no such protective effect. This protective event was independent of the expression of Fas ligand on the tumor cells. Interrupting the β integrins-matrix interaction diminished the coculture effect. In Jurkat cells, cell matrix contact reduced the assembly of the Fas death-inducing signaling complex and Bcl-xL cleavage, but enhanced the phosphorylation of ERK1/2, p38 MAPK, and Akt. Only PI3K inhibitor, but not kinase inhibitors for MEK, ERK1/2, p38 MAPK, JNK, protein kinase C, and protein kinase A, completely abolished this tumor cell contact-associated protection and in parallel restored Fas-induced Bcl-xL cleavage as well as decreasing the phosphorylation of Bad at serine 136. Together, our results indicate that stimulation of the β integrin signal of T cells by contact with tumor cells may trigger a novel protective signaling through the PI3K/Akt pathway of T cells against Fas-mediated apoptosis.
Calcineurin Negatively Regulates TLR-Mediated Activation Pathways
Authors: Kang Young Jun , Kusler Brenda , Otsuka Motoyuki , Hughes Michael , Suzuki Nobutaka , Suzuki Shinobu , Yeh Wen-Chen , Akira Shizuo , Han Jiahuai , Jones Patricia P.
Published: April 2014

In innate immunity, microbial components stimulate macrophages to produce antimicrobial substances, cytokines, other proinflammatory mediators, and IFNs via TLRs, which trigger signaling pathways activating NF-κB, MAPKs, and IFN response factors. We show in this study that, in contrast to its activating role in T cells, in macrophages the protein phosphatase calcineurin negatively regulates NF-κB, MAPKs, and IFN response factor activation by inhibiting the TLR-mediated signaling pathways. Evidence for this novel role for calcineurin was provided by the findings that these signaling pathways are activated when calcineurin is inhibited either by the inhibitors cyclosporin A or FK506 or by small interfering RNA-targeting calcineurin, and that activation of these pathways by TLR ligands is inhibited by the overexpression of a constitutively active form of calcineurin. We further found that IκB-α degradation, MAPK activation, and TNF-α production by FK506 were reduced in macrophages from mice deficient in MyD88, Toll/IL-1R domain-containing adaptor-inducing IFN-β (TRIF), TLR2, or TLR4, whereas macrophages from TLR3-deficient or TLR9 mutant mice showed the same responses to FK506 as those of wild-type cells. Biochemical studies indicate that calcineurin interacts with MyD88, TRIF, TLR2, and TLR4, but not with TLR3 or TLR9. Collectively, these results suggest that calcineurin negatively regulates TLR-mediated activation pathways in macrophages by inhibiting the adaptor proteins MyD88 and TRIF, and a subset of TLRs.
Qa-1b-Dependent Modulation of Dendritic Cell and NK Cell Cross-Talk In Vivo
Authors: Colmenero Paula , Zhang Angela L. , Qian Ting , Lu Linrong , Cantor Harvey , Söderström Kalle , Engleman Edgar G.
Published: April 2014

Dendritic cells (DC) trigger activation and IFN-γ release by NK cells in lymphoid tissues, a process important for the polarization of Th1 responses. Little is known about the molecular signals that regulate DC-induced NK cell IFN-γ synthesis. In this study, we analyzed whether the interaction between Qa-1b expressed on DC and its CD94/NKG2A receptor on NK cells affects this process. Activation of DC using CpG-oligodeoxynucleotides in Qa-1b-deficient mice, or transfer of CpG-oligodeoxynucleotide-activated Qa-1b-deficient DC into wild-type mice, resulted in dramatically increased IFN-γ production by NK cells, as compared with that induced by Qa-1b-expressing DC. Masking the CD94/NKG2A inhibitory receptor on NK cells in wild-type mice similarly enhanced the IFN-γ response of these cells to Qa-1b-expressing DC. Furthermore, NK cells from CD94/NKG2A-deficient mice displayed higher IFN-γ production upon DC stimulation. These results demonstrate that Qa-1b is critically involved in regulating IFN-γ synthesis by NK cells in vivo through its interaction with CD94/NKG2A inhibitory receptors. This receptor-ligand interaction may be essential to prevent unabated cytokine production by NK cells during an inflammatory response.
All-trans Retinoic Acid Enhances Murine Dendritic Cell Migration to Draining Lymph Nodes via the Balance of Matrix Metalloproteinases and Their Inhibitors
Authors: Darmanin Stephanie , Chen Jian , Zhao Songji , Cui Hongyan , Shirkoohi Reza , Kubo Naoki , Kuge Yuji , Tamaki Nagara , Nakagawa Koji , Hamada Jun-ichi , Moriuchi Tetsuya , Kobayashi Masanobu
Published: April 2014

Cancers escape immune surveillance through the manipulation of the host’s immune system. Sequestration of dendritic cells (DCs) within tumor tissues and the subsequent inhibition of their migration is one of the several mechanisms by which tumors induce immunosuppression. In view of recent findings depicting the improvement of tumor immune responses in cancer patients following all-trans retinoic acid (ATRA) treatment, we sought to identify the effects of ATRA on DC mobility in the context of tumor immunotherapy. Our results demonstrate that ATRA, added to differentiating murine bone marrow progenitor cells, enhances the invasive capacity of the resulting DCs. Immature DCs injected intratumorally in mice show increased accumulation in draining lymph nodes, but not in nondraining lymph nodes and spleens, when differentiated in the presence of ATRA. The in vitro migration of mature DCs through the basement membrane matrix toward the lymphoid chemokines CCL19 and CCL21 is enhanced in these cells, albeit not in the presence of a matrix metalloproteinase (MMP) inhibitor. An increase in MMP production with a simultaneous decrease in the production of their inhibitors (tissue inhibitors of matrix metalloproteinase or TIMPs) is provoked by ATRA. This affects the MMP/TIMP balance in DCs, in particular that of MMP-9 and TIMP-1, favoring protease activity and thus allowing for enhanced DC mobilization. In conclusion, this study demonstrates that ATRA is capable of improving DC trafficking in a tumor milieu and, in view of the encouraging results obtained in the clinic, further supports the notion that ATRA might be a valuable chemical adjuvant to current immunotherapeutic strategies for cancer.