Ticks are ectoparasitic arthropods that can transmit a variety of microorganisms to humans and animals during blood feeding, causing serious infectious disorders, including Lyme disease. Acaricides are pharmacologic agents that kill ticks. The emergence of acaricide-resistant ticks calls for alternative control strategies for ticks and tick-borne diseases. Many animals develop resistance to ticks after repeated infestations, but the nature of this acquired anti-tick immunity remains poorly understood. Here we investigated the cellular and molecular mechanisms underlying acquired resistance to Haemaphysalis longicornis ticks in mice and found that antibodies were required, as was IgFc receptor expression on basophils but not on mast cells. The infiltration of basophils at tick-feeding sites occurred during the second, but not the first, tick infestation. To assess the requirement for basophil infiltration to acquired tick resistance, mice expressing the human diphtheria toxin receptor under the control of the mast cell protease 8 (Mcpt8) promoter were generated. Diphtheria toxin administration to these mice selectively ablated basophils. Diphtheria toxin–mediated basophil depletion before the second tick infestation resulted in loss of acquired tick resistance. These data provide the first clear evidence, to our knowledge, that basophils play an essential and nonredundant role in antibody-mediated acquired immunity against ticks, which may suggest new strategies for controlling tick-borne diseases.
Takeshi Wada, Kenji Ishiwata, Haruhiko Koseki, Tomoyuki Ishikura, Tsukasa Ugajin, Naotsugu Ohnuma, Kazushige Obata, Ryosuke Ishikawa, Soichiro Yoshikawa, Kaori Mukai, Yohei Kawano, Yoshiyuki Minegishi, Hiroo Yokozeki, Naohiro Watanabe, Hajime Karasuyama
Studies in mice and humans have revealed that the T cell, immunoglobulin, mucin (TIM) genes are associated with several atopic diseases. TIM-1 is a type I membrane protein that is expressed on T cells upon stimulation and has been shown to modulate their activation. In addition to a recently described interaction with dendritic cells, TIM-1 has also been identified as a phosphatidylserine recognition molecule, and several protein ligands have been proposed. Our understanding of its activity is complicated by the possibility that TIM-1 possesses multiple and diverse binding partners. In order to delineate the function of TIM-1, we generated monoclonal antibodies directed to a cleft formed within the IgV domain of TIM-1. We have shown here that antibodies that bind to this defined cleft antagonize TIM-1 binding to specific ligands and cells. Notably, these antibodies exhibited therapeutic activity in a humanized SCID model of experimental asthma, ameliorating inflammation, and airway hyperresponsiveness. Further experiments demonstrated that the effects of the TIM-1–specific antibodies were mediated via suppression of Th2 cell proliferation and cytokine production. These results demonstrate that modulation of the TIM-1 pathway can critically influence activated T cells in a humanized disease model, suggesting that TIM-1 antagonists may provide potent therapeutic benefit in asthma and other immune-mediated disorders.
Sanchaita Sriwal Sonar, Yen-Ming Hsu, Melanie Lynn Conrad, Gerard R. Majeau, Ayse Kilic, Ellen Garber, Yan Gao, Chioma Nwankwo, Gundi Willer, Jan C. Dudda, Hellen Kim, Véronique Bailly, Axel Pagenstecher, Paul D. Rennert, Harald Renz
The renin-angiotensin-aldosterone system (RAAS) is a key hormonal system regulating blood pressure. However, expression of RAAS components has recently been detected in immune cells, and the RAAS has been implicated in several mouse models of autoimmune disease. Here, we have identified Ang II as a paracrine mediator, sustaining inflammation in the CNS in the EAE mouse model of MS via TGF-β. Ang II type 1 receptors (AT1Rs) were found to be primarily expressed in CNS-resident cells during EAE. In vitro, astrocytes and microglia responded to Ang II treatment by inducing TGF-β expression via a pathway involving the TGF-β–activating protease thrombospondin-1 (TSP-1). TGF-β upregulation in astrocytes and microglia during EAE was blocked with candesartan (CA), an inhibitor of AT1R. Treatment of EAE with CA ameliorated paralysis and blunted lymphocyte infiltration into the CNS, outcomes that were also seen with genetic ablation of AT1Ra and treatment with an inhibitor of TSP-1. These data suggest that AT1R antagonists, frequently prescribed as antihypertensives, may be useful to interrupt this proinflammatory, CNS-specific pathway in individuals with MS.
Tobias V. Lanz, Zhaoqing Ding, Peggy P. Ho, Jian Luo, Ankur N. Agrawal, Hrishikesh Srinagesh, Robert Axtell, Hui Zhang, Michael Platten, Tony Wyss-Coray, Lawrence Steinman
Evan Nair-Gill, Stephanie M. Wiltzius, Xiao X. Wei, Donghui Cheng, Mireille Riedinger, Caius G. Radu, Owen N. Witte
Abetalipoproteinemia (ABL) is a rare Mendelian disorder of lipid metabolism due to genetic deficiency in microsomal triglyceride transfer protein (MTP). It is associated with defects in MTP-mediated lipid transfer onto apolipoprotein B (APOB) and impaired secretion of APOB-containing lipoproteins. Recently, MTP was shown to regulate the CD1 family of lipid antigen-presenting molecules, but little is known about immune function in ABL patients. Here, we have shown that ABL is characterized by immune defects affecting presentation of self and microbial lipid antigens by group 1 (CD1a, CD1b, CD1c) and group 2 (CD1d) CD1 molecules. In dendritic cells isolated from ABL patients, MTP deficiency was associated with increased proteasomal degradation of group 1 CD1 molecules. Although CD1d escaped degradation, it was unable to load antigens and exhibited functional defects similar to those affecting the group 1 CD1 molecules. The reduction in CD1 function resulted in impaired activation of CD1-restricted T and invariant natural killer T (iNKT) cells and reduced numbers and phenotypic alterations of iNKT cells consistent with central and peripheral CD1 defects in vivo. These data highlight MTP as a unique regulator of human metabolic and immune pathways and reveal that ABL is not only a disorder of lipid metabolism but also an immune disease involving CD1.
Sebastian Zeissig, Stephanie K. Dougan, Duarte C. Barral, Yvonne Junker, Zhangguo Chen, Arthur Kaser, Madelyn Ho, Hannah Mandel, Adam McIntyre, Susan M. Kennedy, Gavin F. Painter, Natacha Veerapen, Gurdyal S. Besra, Vincenzo Cerundolo, Simon Yue, Sarah Beladi, Samuel M. Behar, Xiuxu Chen, Jenny E. Gumperz, Karine Breckpot, Anna Raper, Amanda Baer, Mark A. Exley, Robert A. Hegele, Marina Cuchel, Daniel J. Rader, Nicholas O. Davidson, Richard S. Blumberg
The inhibitory receptor programmed death 1 (PD-1) is upregulated on antigen-specific CD8+ T cells during persistent viral infections. Interaction with PD-1 ligand 1 (PD-L1) contributes to functional exhaustion of responding T cells and may limit immunopathology during infection. PD-L1 is expressed on both hematopoietic and nonhematopoietic cells in tissues. However, the exact roles of PD-L1 on hematopoietic versus nonhematopoietic cells in modulating immune responses are unclear. Here we used bone marrow chimeric mice to examine the effects of PD-L1 deficiency in hematopoietic or nonhematopoietic cells during lymphocytic choriomeningitis virus clone 13 (LCMV CL-13) infection. We found that PD-L1 expression on hematopoietic cells inhibited CD8+ T cell numbers and function after LCMV CL-13 infection. In contrast, PD-L1 expression on nonhematopoietic cells limited viral clearance and immunopathology in infected tissues. Together, these data demonstrate that there are distinct roles for PD-L1 on hematopoietic and nonhematopoietic cells in regulating CD8+ T cell responses and viral clearance during chronic viral infection.
Scott N. Mueller, Vijay K. Vanguri, Sang-Jun Ha, Erin E. West, Mary E. Keir, Jonathan N. Glickman, Arlene H. Sharpe, Rafi Ahmed
Neutrophils are a major component of the innate immune response. Their homeostasis is maintained, in part, by the regulated release of neutrophils from the bone marrow. Constitutive expression of the chemokine CXCL12 by bone marrow stromal cells provides a key retention signal for neutrophils in the bone marrow through activation of its receptor, CXCR4. Attenuation of CXCR4 signaling leads to entry of neutrophils into the circulation through unknown mechanisms. We investigated the role of CXCR2-binding ELR+ chemokines in neutrophil trafficking using mouse mixed bone marrow chimeras reconstituted with Cxcr2–/– and WT cells. In this context, neutrophils lacking CXCR2 were preferentially retained in the bone marrow, a phenotype resembling the congenital disorder myelokathexis, which is characterized by chronic neutropenia. Additionally, transient disruption of CXCR4 failed to mobilize Cxcr2–/– neutrophils. However, neutrophils lacking both CXCR2 and CXCR4 displayed constitutive mobilization, showing that CXCR4 plays a dominant role in neutrophil trafficking. With regard to CXCR2 ligands, bone marrow endothelial cells and osteoblasts constitutively expressed the ELR+ chemokines CXCL1 and CXCL2, and CXCL2 expression was induced in endothelial cells during G-CSF–induced neutrophil mobilization. Collectively, these data suggest that CXCR2 signaling is a second chemokine axis that interacts antagonistically with CXCR4 to regulate neutrophil release from the bone marrow.
Kyle J. Eash, Adam M. Greenbaum, Priya K. Gopalan, Daniel C. Link
Mutations in the tumor-suppressor gene phosphatase and tensin homolog deleted on chromosome 10 (Pten) are associated with multiple cancers in humans, including T cell malignancies. Targeted deletion of Pten in T cells induces both a disseminated “mature phenotype” lymphoma and a lymphoproliferative autoimmune syndrome in mice. Here, we have shown that these two diseases are separable and mediated by T lineage cells of distinct developmental stages. Loss of PTEN was found to be a powerful driver of lymphomagenesis within the thymus characterized by overexpression of the c-myc oncogene. In an otherwise normal thymic environment, PTEN-deficient T cell lymphomas invariably harbored RAG-dependent reciprocal t(14:15) chromosomal translocations involving the T cell receptor alpha/delta locus and c-myc, and their survival and growth was TCR dependent, but Notch independent. However, lymphomas occurred even if TCR recombination was prevented, although these lymphomas were less mature, arose later in life, and, importantly, were dependent upon Notch pathways to upregulate c-myc expression. In contrast, using the complementary methods of early thymectomy and adoptive transfers, we found that PTEN-deficient mature T cells were unable to undergo malignant transformation but were sufficient for the development of autoimmunity. These data suggest multiple and distinct regulatory roles for PTEN in the molecular pathogenesis of lymphoma and autoimmunity.
Xiaohe Liu, Jodi L. Karnell, Bu Yin, Ruan Zhang, Jidong Zhang, Peiying Li, Yongwon Choi, Jonathan S. Maltzman, Warren S. Pear, Craig H. Bassing, Laurence A. Turka
Establishing long-term allograft acceptance without the requirement for continuous immunosuppression, a condition known as allograft tolerance, is a highly desirable therapeutic goal in solid organ transplantation. Determining which recipients would benefit from withdrawal or minimization of immunosuppression would be greatly facilitated by biomarkers predictive of tolerance. In this study, we identified the largest reported cohort to our knowledge of tolerant renal transplant recipients, as defined by stable graft function and receiving no immunosuppression for more than 1 year, and compared their gene expression profiles and peripheral blood lymphocyte subsets with those of subjects with stable graft function who are receiving immunosuppressive drugs as well as healthy controls. In addition to being associated with clinical and phenotypic parameters, renal allograft tolerance was strongly associated with a B cell signature using several assays. Tolerant subjects showed increased expression of multiple B cell differentiation genes, and a set of just 3 of these genes distinguished tolerant from nontolerant recipients in a unique test set of samples. This B cell signature was associated with upregulation of CD20 mRNA in urine sediment cells and elevated numbers of peripheral blood naive and transitional B cells in tolerant participants compared with those receiving immunosuppression. These results point to a critical role for B cells in regulating alloimmunity and provide a candidate set of genes for wider-scale screening of renal transplant recipients.
Kenneth A. Newell, Adam Asare, Allan D. Kirk, Trang D. Gisler, Kasia Bourcier, Manikkam Suthanthiran, William J. Burlingham, William H. Marks, Ignacio Sanz, Robert I. Lechler, Maria P. Hernandez-Fuentes, Laurence A. Turka, Vicki L. Seyfert-Margolis
The potent regulatory properties of NKT cells render this subset of lipid-specific T cells a promising target for immunotherapeutic interventions. The marine sponge glycolipid α-galactosylceramide (αGalCer) is the prototypic NKT cell agonist, which elicits this function when bound to CD1d. However, our understanding of the in vivo properties of NKT cell agonists and the host factors that control their bioactivity remains very limited. In this report, we isolated the enzyme fatty acid amide hydrolase (FAAH) from mouse serum as an αGalCer-binding protein that modulates the induction of key effector functions of NKT cells in vivo. FAAH bound αGalCer in vivo and in vitro and was required for the efficient targeting of lipid antigens for CD1d presentation. Immunization of Faah-deficient mice with αGalCer resulted in a reduced systemic cytokine production, but enhanced expansion of splenic NKT cells. This distinct NKT response conferred a drastically increased adjuvant effect and strongly promoted protective CTL responses. Thus, our findings identify not only the presence of FAAH in normal mouse serum, but also its critical role in the tuning of immune responses to lipid antigens by orchestrating their transport and targeting for NKT cell activation. Our results suggest that the serum transport of lipid antigens directly shapes the quality of NKT cell responses, which could potentially be modulated in support of novel vaccination strategies.
Stefan Freigang, Victoria Zadorozhny, Michele K. McKinney, Philippe Krebs, Rana Herro, Joanna Pawlak, Lisa Kain, Nicolas Schrantz, Kim Masuda, Yang Liu, Paul B. Savage, Albert Bendelac, Benjamin F. Cravatt, Luc Teyton