Browsing by Subject "Dendritic cells."
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Item Gene expression profiling to understand the alterations in the monocyte compartment of pediatric systemic lupus erythematosus.(2008-06-11T17:41:33Z) Patel, Pinakeen Shankarbhai.; Pascual, Virginia.; Banchereau, Jacques.; Biomedical Studies.; Baylor University. Institute of Biomedical Studies.Blood monocytes from SLE patients display DC function, as they are able to induce the proliferation of allogeneic T cells. Furthermore, sera from SLE patients induce healthy monocytes to differentiate into DCs. This DC-inducing property is in part due to the presence of type-I IFNs in SLE sera, as well as other, yet uncharacterized factors. To understand these alterations, we performed a thorough phenotypic analysis and gene expression profiling of monocytes from children with active, newly diagnosed and untreated disease. Phenotypic analysis of freshly isolated SLE blood monocytes revealed a modest expansion of CD14highCD16+ cells and an otherwise lack of expression of molecules related to DC function. Further characterization of a fraction of SLE monocytes inducing allogeneic T cell proliferation revealed that upon contact with T cells, SLE monocytes secrete proinflammatory cytokines such as IL-1 and IL-6 and do upregulate expression of innate immunity receptors involved in DC differentiation and molecules responsible for antigen presentation. To recapitulate the initial events leading to monocyte differentiation in this disease, we studied the effects of SLE serum on healthy monocyte at the trasncriptional and protein levels. These studies revealed the upregulation of expression on these cells of chemokine receptor such as CX3CR1 and CCR7, which may lead to the migration of blood monocytes to inflammed tissues and/or secondary lymphoid organs respectively in vivo. There, contact with T cells would lead to the acquisition of antigen presenting function and skewing from tolerogenic to immunogenic responses.Item Humanized mice to test vaccination against influenza virus via dendritic cells.(2008-06-11T14:19:03Z) Yu, Chun-I, 1975-; Palucka, Karolina, 1959-; Banchereau, Jacques.; Biomedical Studies.; Baylor University. Institute of Biomedical Studies.Critical to the development of human vaccines is the availability of in vivo models of the human immune system that permit testing of vaccine efficacy. Here,we used NOD-SCID-β²m-/- immunodeficient mice which, when engrafted with human CD34⁺ hematopoietic progenitors, develop all subsets of human dendritic cells(DCs) and B cells. T cells and their subsets were reconstituted by adoptive transfer. We found myeloid DCs, plasmacytoid DCs and monocytes in the bone marrow, spleen, and peripheral tissues including skin and lungs. To test DC biologyin vivo, we first used live influenza A/PR8/34 (H1N1) virus. Upon intranasal inoculation, all subsets of human antigen presenting cells were activated. Matured DCs were found accumulated in mediastinal lymph nodes. To evaluate the value of these mice for testing human vaccines, humanized mice were immunized with1) ex vivo-generated DCs, 2) seasonal influenza vaccines and 3) protein antigens fused to anti-DC receptor. Upon vaccination with ex vivo-generated DCs pulsed with heat-inactivated influenza virus, mice developed influenza-specific immunity, i.e. influenza-specific immunoglobulins (Igs) in the serum and influenza virus matrix protein 1 (FluM1)-specific CD8⁺ T cells in the blood, spleen and lungs. Influenza-specific Igs were protective as sera from vaccinated mice inhibited influenza virus-induced hemagglutination in vitro and offered passive protection in vivo. Upon vaccination with seasonal influenza vaccines, i.e. live attenuated trivalent vaccine (LAIV) or killed trivalent vaccine (TIV), humanized mice developed both humoral and cellular immunity. Plasma cells differentiation and the secretion of specific Igs were dependent on the reconstitution with CD45RA⁻CD27⁺CD4⁺ central memory T cells. CD8⁺ T cells specific to two influenza antigens, i.e. FluM1 and NS1, were detected in mice vaccinated with LAIV. TIV-vaccinated mice showed the expansion of FluM1, but not NS1, specific CD8⁺ T cells. Antigen-specific CD8⁺ T cells produced IFN-γ and expressed surface CD107a consistent with the acquisition of effector function. Finally, upon vaccination with anti-DC receptor (DCIR)-FluM1 fusion protein and poly I:C as an adjuvant, DCs efficiently cross-presented FluM1 and expanded antigen-specific CD8⁺T cells. Therefore, humanized mice might be valuable model for testing human vaccines against influenza virus.Item Respiratory Syncytial Virus triggers immune tolerance through induction of tolerogenic dendritic cells and expansion of regulatory T cells.(2010-06-23T12:28:05Z) Guo, Haisu.; Connolly, John Edward.; Biomedical Studies.; Baylor University. Institute of Biomedical Studies.Dendritic cells have the ability to control the balance between immunity and tolerance. Upon viral exposure, Dendritic Cells (DCs) steadily detect pathogens and exert their antigen presentation function to induce adaptive T cell response. Respiratory Syncytial Virus (RSV) is an important respiratory pathogen in infants and young children worldwide. Here we show that RSV exposure polarizes DC maturation to a tolerogenic state. RSV exposed DCs (RSV-DCs) are unable to prime allogeneic CD4+ T cell proliferation and cytokine production. Strikingly, RSV exposed DCs are able to efficiently inhibit on-going Mixed Leukocyte Reaction (MLR) in trans. Phenotypic characterization of RSV-DCs indicates that they express a variety of surface inhibitory molecules and secrete high amount of the cytokine IL-10. Autocrine IL-10 receptor signaling is required for tolerogenic conversion. A direct comparison with pharmacologically generated tolerogenic DCs indicates RSV-DCs are much more potent at inhibiting CD4+ T cell alloproliferation. Furthermore, we find that RSV-DCs propagate their tolerogenic signal through expansion of regulatory T cells (Tregs). RSV- DCs induce the selective expansion of CD4+/CD25+/FoxP3+/CTLA+/GITR+ Tregs in the bulk T cell population. These Tregs are able to inhibit on-going MLR in trans, indicating their functional potency. An analysis of the non-proliferating target CD4+ T cells indicates that they are in a state of phenotypic and functional anergy. These T cells express anergy markers and are unresponsive to secondary anti-CD3/CD28 restimulation. Interaction of B7 negative co-stimualtor PD-L1 and its receptor PD-1 are required for Treg expansion and function as blockade led to a reversal of anergy induction in the target population. These in vitro observations led us to investigate the impact of RSV-DCs on immune tolerance in vivo. We did preliminary studies demonstrating RSV exposure induces BALB/c bone marrow derived DCs (BM-DCs) tolerogenic characterized by inhibition of C57BL/6 CD4 T cell alloproliferation and upregulation of mouse PD-L1 molecule. Similarly to what we observed in human cells, RSV-mouse DCs are able to expand a population of CD4+CD25+FoxP3+ regulatory T cells. These cells with immune suppressive function can then be adoptively transferred into murine models of autoimmune diseases and organ transplantion to suppress antigen-specific immune activation in vivo.