from The Journal of Immunology current issue https://ift.tt/2HWmzo5
Showing posts with label The Journal of Immunology current issue. Show all posts
Showing posts with label The Journal of Immunology current issue. Show all posts
Monday, May 7, 2018
Comment on "Development of Asthma in Inner-City Children: Possible Roles of MAIT Cells and Variation in the Home Environment" [LETTERS TO THE EDITOR]
from The Journal of Immunology current issue https://ift.tt/2rr2nj7
Response to Comment on "Development of Asthma in Inner-City Children: Possible Roles of MAIT Cells and Variation in the Home Environment" [LETTERS TO THE EDITOR]
from The Journal of Immunology current issue https://ift.tt/2HVR7WY
Flow Cytometry Data Preparation Guidelines for Improved Automated Phenotypic Analysis [IMMUNOLOGY NOTES AND RESOURCES]
Advances in flow cytometry (FCM) increasingly demand adoption of computational analysis tools to tackle the ever-growing data dimensionality. In this study, we tested different data input modes to evaluate how cytometry acquisition configuration and data compensation procedures affect the performance of unsupervised phenotyping tools. An analysis workflow was set up and tested for the detection of changes in reference bead subsets and in a rare subpopulation of murine lymph node CD103+ dendritic cells acquired by conventional or spectral cytometry. Raw spectral data or pseudospectral data acquired with the full set of available detectors by conventional cytometry consistently outperformed datasets acquired and compensated according to FCM standards. Our results thus challenge the paradigm of one-fluorochrome/one-parameter acquisition in FCM for unsupervised cluster-based analysis. Instead, we propose to configure instrument acquisition to use all available fluorescence detectors and to avoid integration and compensation procedures, thereby using raw spectral or pseudospectral data for improved automated phenotypic analysis.
from The Journal of Immunology current issue https://ift.tt/2rs7OhF
Invariant NKT Cells and Control of the Thymus Medulla [BRIEF REVIEWS]
Most αβ T cells that form in the thymus are generated during mainstream conventional thymocyte development and involve the generation and selection of a diverse αβ TCR repertoire that recognizes self-peptide/MHC complexes. Additionally, the thymus also supports the production of T cell subsets that express αβ TCRs but display unique developmental and functional features distinct from conventional αβ T cells. These include multiple lineages of CD1d-restricted invariant NKT (iNKT) cells that express an invariant αβ TCR, branch off from mainstream thymocytes at the CD4+CD8+ stage, and are potent producers of polarizing cytokines. Importantly, and despite their differences, iNKT cells and conventional αβ T cells share common requirements for thymic epithelial microenvironments during their development. Moreover, emerging evidence suggests that constitutive cytokine production by iNKT cells influences both conventional thymocyte development and the intrathymic formation of additional innate CD8+ αβ T cells with memory-like properties. In this article, we review evidence for an intrathymic innate lymphocyte network in which iNKT cells play key roles in multiple aspects of thymus function.
from The Journal of Immunology current issue https://ift.tt/2KINv8L
Cutting Edge: Blockade of Inhibitor of Apoptosis Proteins Sensitizes Neutrophils to TNF- but Not Lipopolysaccharide-Mediated Cell Death and IL-1{beta} Secretion [CUTTING EDGE]
The mammalian inhibitor of apoptosis proteins (IAPs) are key regulators of cell death and inflammation. A major function of IAPs is to block the formation of a cell death–inducing complex, termed the ripoptosome, which can trigger caspase-8–dependent apoptosis or caspase-independent necroptosis. Recent studies report that upon TLR4 or TNF receptor 1 (TNFR1) signaling in macrophages, the ripoptosome can also induce NLRP3 inflammasome formation and IL-1β maturation. Whether neutrophils have the capacity to assemble a ripoptosome to induce cell death and inflammasome activation during TLR4 and TNFR1 signaling is unclear. In this study, we demonstrate that murine neutrophils can signal via TNFR1-driven ripoptosome assembly to induce both cell death and IL-1β maturation. However, unlike macrophages, neutrophils suppress TLR4-dependent cell death and NLRP3 inflammasome activation during IAP inhibition via deficiencies in the CD14/TRIF arm of TLR4 signaling.
from The Journal of Immunology current issue https://ift.tt/2rr2lI1
Cutting Edge: Protection by Antiviral Memory CD8 T Cells Requires Rapidly Produced Antigen in Large Amounts [CUTTING EDGE]
Numerous attempts to produce antiviral vaccines by harnessing memory CD8 T cells have failed. A barrier to progress is that we do not know what makes an Ag a viable target of protective CD8 T cell memory. We found that in mice susceptible to lethal mousepox (the mouse homolog of human smallpox), a dendritic cell vaccine that induced memory CD8 T cells fully protected mice when the infecting virus produced Ag in large quantities and with rapid kinetics. Protection did not occur when the Ag was produced in low amounts, even with rapid kinetics, and protection was only partial when the Ag was produced in large quantities but with slow kinetics. Hence, the amount and timing of Ag expression appear to be key determinants of memory CD8 T cell antiviral protective immunity. These findings may have important implications for vaccine design.
from The Journal of Immunology current issue https://ift.tt/2HVUJs8
HLA-B*39:06 Efficiently Mediates Type 1 Diabetes in a Mouse Model Incorporating Reduced Thymic Insulin Expression [AUTOIMMUNITY]
Type 1 diabetes (T1D) is characterized by T cell–mediated destruction of the insulin-producing β cells of the pancreatic islets. Among the loci associated with T1D risk, those most predisposing are found in the MHC region. HLA-B*39:06 is the most predisposing class I MHC allele and is associated with an early age of onset. To establish an NOD mouse model for the study of HLA-B*39:06, we expressed it in the absence of murine class I MHC. HLA-B*39:06 was able to mediate the development of CD8 T cells, support lymphocytic infiltration of the islets, and confer T1D susceptibility. Because reduced thymic insulin expression is associated with impaired immunological tolerance to insulin and increased T1D risk in patients, we incorporated this in our model as well, finding that HLA-B*39:06–transgenic NOD mice with reduced thymic insulin expression have an earlier age of disease onset and a higher overall prevalence as compared with littermates with typical thymic insulin expression. This was despite virtually indistinguishable blood insulin levels, T cell subset percentages, and TCR Vβ family usage, confirming that reduced thymic insulin expression does not impact T cell development on a global scale. Rather, it will facilitate the thymic escape of insulin-reactive HLA-B*39:06–restricted T cells, which participate in β cell destruction. We also found that in mice expressing either HLA-B*39:06 or HLA-A*02:01 in the absence of murine class I MHC, HLA transgene identity alters TCR Vβ usage by CD8 T cells, demonstrating that some TCR Vβ families have a preference for particular class I MHC alleles.
from The Journal of Immunology current issue https://ift.tt/2rs7IGP
Netting Neutrophils Activate Autoreactive B Cells in Lupus [AUTOIMMUNITY]
Lupus erythematosus (LE) patients develop autoantibodies that form circulating immune complexes (ICs) with extracellular self-nucleic acids. These ICs are deposited into peripheral tissues, where they trigger detrimental organ inflammation. Recent evidence suggests that ICs contain LL37–DNA complexes derived from neutrophil extracellular traps (NETs) and that LE patients develop pathogenic autoantibodies against these structures, including Abs to LL37. However, the mechanism that leads to the generation of these Abs is unknown. In this study, we show that NETs directly trigger Ab production by human memory B cells. This occurs via LL37–DNA complexes present in NETs, which have the unique ability to gain access to endosomal compartments of B cells and to trigger TLR9 activation. In LE patients, NET-derived LL37–DNA complexes trigger polyclonal B cell activation via TLR9, but also specifically expand self-reactive memory B cells producing anti-LL37 Abs in an Ag-dependent manner. These findings suggest a unique link between neutrophils and B cells in which NETs trigger a concerted activation of TLR9 and BCR leading to anti-NET autoantibody production in lupus.
from The Journal of Immunology current issue https://ift.tt/2KHmToF
Multiple Homozygous Variants in the STING-Encoding TMEM173 Gene in HIV Long-Term Nonprogressors [CLINICAL AND HUMAN IMMUNOLOGY]
Among HIV-infected individuals, long-term nonprogressor (LTNP) patients experience slow CD4 T cell decline and almost undetectable viral load for several years after primary acquisition of HIV. Type I IFN has been suggested to play a pathogenic role in HIV pathogenesis, and therefore diminished IFN responses may underlie the LTNP phenotype. In this study, we examined the presence and possible immunological role of multiple homozygous single-nucleotide polymorphisms in the stimulator of IFN genes (STING) encoding gene TMEM173 involved in IFN induction and T cell proliferation in HIV LTNP patients. We identified LTNPs through the Danish HIV Cohort and performed genetic analysis by Sanger sequencing, covering the R71H-G230A-R293Q (HAQ) single-nucleotide polymorphisms in TMEM173. This was followed by investigation of STING mRNA and protein accumulation as well as innate immune responses and proliferation following STING stimulation and infection with replication-competent HIV in human blood–derived cells. We identified G230A-R293Q/G230A-R293Q and HAQ/HAQ homozygous TMEM173 variants in 2 out of 11 LTNP patients. None of the 11 noncontrollers on antiretroviral treatment were homozygous for these variants. We found decreased innate immune responses to DNA and HIV as well as reduced STING-dependent inhibition of CD4 T cell proliferation, particularly in the HAQ/HAQ HIV LTNP patients, compared with the age- and gender-matched noncontrollers on antiretroviral treatment. These findings suggest that homozygous HAQ STING variants contribute to reduced inhibition of CD4 T cell proliferation and a reduced immune response toward DNA and HIV, which might result in reduced levels of constitutive IFN production. Consequently, the HAQ/HAQ TMEM173 genotype may contribute to the slower disease progression characteristic of LTNPs.
from The Journal of Immunology current issue https://ift.tt/2rs7Gib
CD83 Antibody Inhibits Human B Cell Responses to Antigen as well as Dendritic Cell-Mediated CD4 T Cell Responses [CLINICAL AND HUMAN IMMUNOLOGY]
Anti-CD83 Ab capable of Ab-dependent cellular cytotoxicity can deplete activated CD83+ human dendritic cells, thereby inhibiting CD4 T cell–mediated acute graft-versus-host disease. As CD83 is also expressed on the surface of activated B lymphocytes, we hypothesized that anti-CD83 would also inhibit B cell responses to stimulation. We found that anti-CD83 inhibited total IgM and IgG production in vitro by allostimulated human PBMC. Also, Ag-specific Ab responses to immunization of SCID mice xenografted with human PBMC were inhibited by anti-CD83 treatment. This inhibition occurred without depletion of all human B cells because anti-CD83 lysed activated CD83+ B cells by Ab-dependent cellular cytotoxicity and spared resting (CD83–) B cells. In cultured human PBMC, anti-CD83 inhibited tetanus toxoid–stimulated B cell proliferation and concomitant dendritic cell–mediated CD4 T cell proliferation and expression of IFN- and IL-17A, with minimal losses of B cells (<20%). In contrast, the anti-CD20 mAb rituximab depleted >80% of B cells but had no effect on CD4 T cell proliferation and cytokine expression. By virtue of the ability of anti-CD83 to selectively deplete activated, but not resting, B cells and dendritic cells, with the latter reducing CD4 T cell responses, anti-CD83 may be clinically useful in autoimmunity and transplantation. Advantages might include inhibited expansion of autoantigen- or alloantigen-specific B cells and CD4 T cells, thus preventing further production of pathogenic Abs and inflammatory cytokines while preserving protective memory and regulatory cells.
from The Journal of Immunology current issue https://ift.tt/2HWmrF7
TCF-1 Inhibits IL-17 Gene Expression To Restrain Th17 Immunity in a Stage-Specific Manner [IMMUNE REGULATION]
T cell factor 1 (TCF-1) is expressed in both developing and mature T cells and has been shown to restrain mature T cell–mediated Th17 responses by inhibiting IL-17 expression. However, it is not clear when TCF-1 is required in vivo to restrain the magnitude of peripheral Th17 responses and what the molecular mechanisms responsible for TCF-1–regulated IL-17 gene expression are. In this study, we showed that conditional deletion of TCF-1 at the early but not later CD4+CD8+ double-positive stage in mice enhanced Th17 differentiation and aggravated experimental autoimmune encephalomyelitis, which correlates with abnormally high IL-17 expression. Expression of TCF-1 in TCF-1–deficient thymocytes but not TCF-1–deficient Th17 cells inhibited IL-17 expression. TCF-1 binds to IL-17 promoter regions, and deletion of two TCF-1 binding sites relieves TCF-1–mediated inhibition of IL-17 promoter activity. Lastly, wild-type TCF-1, but not a TCF-1 mutant that has no intrinsic histone deacetylase activity, was able to inhibit IL-17 expression in TCF-1 deficient mouse thymocytes. Thus, our study demonstrates the requirement of TCF-1 in vivo at stages earlier than double-positive cells to restrain peripheral Th17 immunity by directly binding and inhibiting IL-17 promoter in its intrinsic histone deacetylase–dependent manner.
from The Journal of Immunology current issue https://ift.tt/2rr2fA9
Stearic Acid Induces CD11c Expression in Proinflammatory Macrophages via Epidermal Fatty Acid Binding Protein [IMMUNE REGULATION]
Obesity is associated with elevated levels of free fatty acids (FAs) and proinflammatory CD11c+ macrophages. However, whether and how free FAs contribute to CD11c+ macrophage differentiation and proinflammatory functions remain unclear. Here we report that dietary saturated FAs, but not unsaturated FAs, promoted the differentiation and function of CD11c+ macrophages. Specifically, we demonstrated that stearic acid (SA) significantly induced CD11c expression in monocytes through activation of the nuclear retinoid acid receptor. More importantly, cytosolic expression of epidermal FA binding protein (E-FABP) in monocytes/macrophages was shown to be critical to the mediation of the SA-induced effect. Depletion of E-FABP not only inhibited SA-induced CD11c upregulation in macrophages in vitro but also abrogated high-saturated-fat diet–induced skin lesions in obese mouse models in vivo. Altogether, our data demonstrate a novel mechanism by which saturated FAs promote obesity-associated inflammation through inducing E-FABP/retinoid acid receptor–mediated differentiation of CD11c+ macrophages.
from The Journal of Immunology current issue https://ift.tt/2KINuSf
Crk Adaptor Proteins Regulate NK Cell Expansion and Differentiation during Mouse Cytomegalovirus Infection [IMMUNE REGULATION]
Natural killer cells are critical in the immune response to infection and malignancy. Prior studies have demonstrated that Crk family proteins can influence cell apoptosis, proliferation, and cell transformation. In this study, we investigated the role of Crk family proteins in mouse NK cell differentiation and host defense using a mouse CMV infection model. The number of NK cells, maturational state, and the majority of the NKR repertoire was similar in Crk x Crk-like (CrkL)–double-deficient and wild type NK cells. However, Crk family proteins were required for optimal activation, IFN- production, expansion, and differentiation of Ly49H+ NK cells, as well as host defense during mouse CMV infection. The diminished function of Crk x CrkL–double-deficient NK cells correlated with decreased phosphorylation of STAT4 and STAT1 in response to IL-12 and IFN-α stimulation, respectively. Together, our findings analyzing NK cell–specific Crk-deficient mice provide insights into the role of Crk family proteins in NK cell function and host defense.
from The Journal of Immunology current issue https://ift.tt/2rs7AXR
Tuning T Cell Signaling Sensitivity Alters the Behavior of CD4+ T Cells during an Immune Response [IMMUNE REGULATION]
Intricate processes in the thymus and periphery help curb the development and activation of autoreactive T cells. The subtle signals that govern these processes are an area of great interest, but tuning TCR sensitivity for the purpose of affecting T cell behavior remains technically challenging. Previously, our laboratory described the derivation of two TCR-transgenic CD4 T cell mouse lines, LLO56 and LLO118, which recognize the same cognate Listeria epitope with the same affinity. Despite the similarity of the two TCRs, LLO56 cells respond poorly in a primary infection whereas LLO118 cells respond robustly. Phenotypic examination of both lines revealed a substantial difference in their surface of expression of CD5, which serves as a dependable readout of the self-reactivity of a cell. We hypothesized that the increased interaction with self by the CD5-high LLO56 was mediated through TCR signaling, and was involved in the characteristic weak primary response of LLO56 to infection. To explore this issue, we generated an inducible knock-in mouse expressing the self-sensitizing voltage-gated sodium channel Scn5a. Overexpression of Scn5a in peripheral T cells via the CD4-Cre promoter resulted in increased TCR-proximal signaling. Further, Scn5a-expressing LLO118 cells, after transfer into BL6 recipient mice, displayed an impaired response during infection relative to wild-type LLO118 cells. In this way, we were able to demonstrate that tuning of TCR sensitivity to self can be used to alter in vivo immune responses. Overall, these studies highlight the critical relationship between TCR–self-pMHC interaction and an immune response to infection.
from The Journal of Immunology current issue https://ift.tt/2KHGlkZ
Crucial Role of Linear Ubiquitin Chain Assembly Complex-Mediated Inhibition of Programmed Cell Death in TLR4-Mediated B Cell Responses and B1b Cell Development [IMMUNE REGULATION]
Linear ubiquitin chain assembly complex (LUBAC)-mediated linear polyubiquitin plays crucial roles in thymus-dependent and -independent type II Ab responses and B1 cell development. In this study, we analyzed the role of LUBAC in TLR-mediated B cell responses. A mouse strain in which LUBAC activity was ablated specifically in B cells (B-HOIPlinear mice) showed defective Ab responses to a type I thymus–independent Ag, NP-LPS. B cells from B-HOIPlinear mice (HOIPlinear B cells) underwent massive cell death in response to stimulation of TLR4, but not TLR9. TLR4 stimulation induced caspase-8 activation in HOIPlinear B cells; this phenomenon, as well as TLR4-induced cell death, was suppressed by ablation of TRIF, a signal inducer specific for TLR4. In addition, LPS-induced survival, proliferation, and differentiation into Ab-producing cells of HOIPlinear B cells were substantially restored by inhibition of caspases together with RIP3 deletion, but not by RIP3 deletion alone, suggesting that LPS stimulation kills HOIPlinear B cells by apoptosis elicited via the TRIF pathway. Further examination of the roles of cell death pathways in B-HOIPlinear mice revealed that deletion of RIP3 increased the number of B1 cells, particularly B1b cells, in B-HOIPlinear mice, indicating that B1b cell homeostasis is controlled via LUBAC-mediated suppression of necroptosis. Taken together, the data show that LUBAC regulates TLR4-mediated B cell responses and B1b cell development and/or maintenance by inhibiting programmed cell death.
from The Journal of Immunology current issue https://ift.tt/2rs7AqP
c-Myb Coordinates Survival and the Expression of Genes That Are Critical for the Pre-BCR Checkpoint [IMMUNE SYSTEM DEVELOPMENT]
The c-Myb transcription factor is required for adult hematopoiesis, yet little is known about c-Myb function during lineage-specific differentiation due to the embryonic lethality of Myb-null mutations. We previously used tissue-specific inactivation of the murine Myb locus to demonstrate that c-Myb is required for differentiation to the pro-B cell stage, survival during the pro-B cell stage, and the pro-B to pre-B cell transition during B lymphopoiesis. However, few downstream mediators of c-Myb–regulated function have been identified. We demonstrate that c-Myb regulates the intrinsic survival of CD19+ pro-B cells in the absence of IL-7 by repressing expression of the proapoptotic proteins Bmf and Bim and that levels of Bmf and Bim mRNA are further repressed by IL-7 signaling in pro-B cells. c-Myb regulates two crucial components of the IL-7 signaling pathway: the IL-7Rα-chain and the negative regulator SOCS3 in CD19+ pro-B cells. Bypassing IL-7R signaling through constitutive activation of Stat5b largely rescues survival of c-Myb–deficient pro-B cells, whereas constitutively active Akt is much less effective. However, rescue of pro-B cell survival is not sufficient to rescue proliferation of pro-B cells or the pro-B to small pre-B cell transition, and we further demonstrate that c-Myb–deficient large pre-B cells are hypoproliferative. Analysis of genes crucial for the pre-BCR checkpoint demonstrates that, in addition to IL-7Rα, the genes encoding 5, cyclin D3, and CXCR4 are downregulated in the absence of c-Myb, and 5 is a direct c-Myb target. Thus, c-Myb coordinates survival with the expression of genes that are required during the pre-BCR checkpoint.
from The Journal of Immunology current issue https://ift.tt/2HYd8o2
Blocking IL-2 Signal In Vivo with an IL-2 Antagonist Reduces Tumor Growth through the Control of Regulatory T Cells [IMMUNOTHERAPY AND VACCINES]
IL-2 is critical for peripheral tolerance mediated by regulatory T (Treg) cells, which represent an obstacle for effective cancer immunotherapy. Although IL-2 is important for effector (E) T cell function, it has been hypothesized that therapies blocking IL-2 signals weaken Treg cell activity, promoting immune responses. This hypothesis has been partially tested using anti–IL-2 or anti–IL-2R Abs with antitumor effects that cannot be exclusively attributed to lack of IL-2 signaling in vivo. In this work, we pursued an alternative strategy to block IL-2 signaling in vivo, taking advantage of the trimeric structure of the IL-2R. We designed an IL-2 mutant that conserves the capacity to bind to the αβ-chains of the IL-2R but not to the c-chain, thus having a reduced signaling capacity. We show our IL-2 mutein inhibits IL-2 Treg cell–dependent differentiation and expansion. Moreover, treatment with IL-2 mutein reduces Treg cell numbers and impairs tumor growth in mice. A mathematical model was used to better understand the effect of the mutein on Treg and E T cells, suggesting suitable strategies to improve its design. Our results show that it is enough to transiently inhibit IL-2 signaling to bias E and Treg cell balance in vivo toward immunity.
from The Journal of Immunology current issue https://ift.tt/2HWmkJH
Efficacy and Mechanism of Antitumor Activity of an Antibody Targeting Transferrin Receptor 1 in Mouse Models of Human Multiple Myeloma [IMMUNOTHERAPY AND VACCINES]
The transferrin receptor 1 (TfR1) is an attractive target for Ab-mediated cancer therapy. We previously developed a mouse/human chimeric IgG3 Ab (ch128.1) targeting human TfR1, which exhibits direct in vitro cytotoxicity against certain human malignant B cells through TfR1 degradation and iron deprivation. ch128.1 also demonstrates exceptional antitumor activity against the B cell malignancy multiple myeloma (MM) in xenograft models of SCID-Beige mice bearing either disseminated ARH-77 or KMS-11 cells in an early disease setting. Interestingly, this activity is observed even against KMS-11 cells, which show no sensitivity to the direct cytotoxic activity of ch128.1 in vitro. To understand the contributions of the Fc fragment, we generated a ch128.1 mutant with impaired binding to FcRs and to the complement component C1q, which retains binding to the neonatal Fc receptor. We now report that this mutant Ab does not show antitumor activity in these two MM models, indicating a crucial role of the Fc fragment in the antitumor activity of ch128.1, which can be attributed to effector functions (Ab-dependent cell-mediated cytotoxicity, Ab-dependent cell-mediated phagocytosis, and/or complement-dependent cytotoxicity). Interestingly, in the KMS-11 model, complement depletion does not affect protection, whereas macrophage depletion does. Consistent with this observation, we found that ch128.1 induces Ab-dependent cell-mediated cytotoxicity and Ab-dependent cell-mediated phagocytosis against KMS-11 cells in the presence of murine bone marrow–derived macrophages. Finally, we found that ch128.1 therapy effectively increases survival in a late MM disease setting. Our results suggest that macrophages play a major role in ch128.1-mediated antitumor protection in our models and that ch128.1 can be effective against human B cell malignancies such as MM.
from The Journal of Immunology current issue https://ift.tt/2rr2b3n
