Immunology
Abstract
Alloantibodies in pre-sensitized transplant candidates deposit complement membrane attack complexes (MAC) on graft endothelial cells (ECs), increasing risk of CD8+ T cell-mediated acute rejection. We recently showed (a) human ECs endocytose MAC into Rab5+ endosomes, creating a signaling platform that stabilizes NF-κB–inducing kinase (NIK) protein; (b) endosomal NIK activates both non-canonical NF-κB signaling to synthesize pro-IL-1β and an NLRP3 inflammasome to process and secrete active IL-1β; and (c) IL-1β activates ECs, increasing recruitment and activation of alloreactive effector memory CD4+ T (TEM) cells. Here, we report IFN-γ priming induced nuclear expression of IL-15/IL-15Rα complexes in cultured human ECs and that MAC-induced IL-1β stimulated translocation of IL-15/IL-15Rα complexes to the EC surface in a canonical NF-κB-dependent process, where IL-15/IL-15Rα transpresentation increased activation and maturation of alloreactive CD8+ TEM. Blocking NLRP3 inflammasome assembly, IL-1 receptor or IL-15 on ECs inhibited the augmented CD8+ TEM responses, indicating this pathway was not redundant. Adoptively transferred alloantibody and mouse complement deposition induced IL-15/IL-15Rα expression by human ECs lining human coronary artery grafts in immunodeficient mice and enhanced intimal CD8+ T cell infiltration, which was markedly reduced by inflammasome inhibition, linking alloantibody to acute rejection. Inhibiting MAC signaling may similarly limit other complement-mediated pathologies.
Authors
Catherine B. Xie, Bo Jiang, Lingfeng Qin, George Tellides, Nancy C. Kirkiles-Smith, Dan Jane-wit, Jordan S. Pober
Abstract
Single nucleotide polymorphisms and locus amplification link the NF-κB transcription factor c-Rel to human autoimmune diseases and B cell lymphomas, respectively. However, the functional consequences of enhanced c-Rel levels remain enigmatic. Here, we overexpressed c-Rel specifically in mouse B cells from BAC-transgenic gene loci and demonstrate that c-Rel protein levels linearly dictated expansion of germinal center (GC) B cells and isotype-switched plasma cells. c-Rel expression in B cells of otherwise c-Rel-deficient mice fully rescued terminal B cell differentiation, underscoring its critical B cell-intrinsic roles. Unexpectedly, in GCB cells transcription-independent regulation produced the highest c-Rel protein levels amongst B cell subsets. In c-Rel overexpressing GCB cells this caused enhanced nuclear translocation, a profoundly altered transcriptional program and increased proliferation. Finally, we provide a link between c-Rel gain and autoimmunity by showing that c-Rel overexpression in B cells caused autoantibody production and renal immune complex deposition.
Authors
Maike Kober-Hasslacher, Hyunju Oh-Strauß, Dilip Kumar, Valeria Soberón, Carina Diehl, Maciej Lech, Thomas Engleitner, Eslam Katab, Vanesa Fernandez Saiz, Guido Piontek, Hongwei Li, Björn Menze, Christoph Ziegenhain, Wolfgang Enard, Roland Rad, Jan P. Böttcher, Hans-Joachim Anders, Martina Rudelius, Marc Schmidt-Supprian
Abstract
Plasmacytoid dendritic cells (pDC), the major producers of Type I interferon, are principally recognized as key mediators of antiviral immunity. However, their role in tumor immunity is less clear. Depending on the context, pDC can both promote or suppress antitumor immune responses. In this study, we identified a naturally occurring pDC subset expressing high levels of OX40 (OX40+ pDC) enriched in the tumor microenvironment (TME) of head and neck squamous cell carcinoma. OX40+ pDC were distinguished by a distinct immunostimulatory phenotype, cytolytic function and ability to synergize with conventional dendritic cells (cDC) in generating potent tumor antigen-specific CD8+ T cell responses. Transcriptomically, we found they selectively utilized EIF2 signaling and oxidative phosphorylation pathways. Moreover, depletion of pDC in the murine OX40+ pDC-rich tumor model accelerated tumor growth. Collectively, we present evidence of a pDC subset in the TME that favors antitumor immunity.
Authors
Kate O. Poropatich, Donye Dominguez, Wen-Ching Chan, Jorge Andrade, Yuanyuan Zha, Brian D. Wray, Jason Miska, Lei Qin, Lisa E. Cole, Sydney Coates, Urjeet A. Patel, Sandeep Samant, Bin Zhang
Abstract
As treatment of the early, inflammatory phase of sepsis improves, post-sepsis immunosuppression and secondary infection have increased in importance. How early inflammation drives immunosuppression remains unclear. Although IFNγ typically helps microbial clearance, we found that increased plasma IFNγ in early clinical sepsis was associated with the later development of secondary Candida infection. Consistent with this observation, we found that exogenous IFNγ suppressed macrophage phagocytosis of zymosan in vivo, and antibody blockade of IFNγ after endotoxemia improved survival of secondary candidemia. Transcriptomic analysis of innate lymphocytes during endotoxemia suggested that NKT cells drove IFNγ production by NK cells via mTORC1. Activation of iNKT cells with glycolipid antigen drove immunosuppression. Deletion of iNKT cells in Cd1d-/- mice or inhibition of mTOR by rapamycin reduced immunosuppression and susceptibility to secondary Candida infection. Thus, although rapamycin is typically an immunosuppressive medication, in the context of sepsis, rapamycin has the opposite effect. These results implicated a NKT cell-mTOR-IFNγ axis in immunosuppression following endotoxemia or sepsis. In summary, in vivo iNKT cells activated mTORC1 in NK cells to produce IFNγ , which worsened macrophage phagocytosis, clearance of secondary Candida infection and mortality.
Authors
Edy Y. Kim, Hadas Ner-Gaon, Jack Varon, Aidan M. Cullen, Jingyu Guo, Jiyoung Choi, Diana Barragan-Bradford, Angelica Higuera, Mayra Pinilla-Vera, Samuel A.P. Short, Antonio J. Arciniegas-Rubio, Tomoyoshi Tamura, David E. Leaf, Rebecca M. Baron, Tal Shay, Michael B. Brenner
Abstract
Neutrophil accumulation is associated with lung pathology during active tuberculosis (ATB). However, the molecular mechanism(s) by which neutrophils accumulate in the lung and contribute to TB immunopathology is not fully delineated. Using the well-established mouse model of TB, our new data provides evidence that the alarmin S100A8/A9 mediates neutrophil accumulation during progression to chronic TB. Depletion of neutrophils or S100A8/A9 deficiency resulted in improved Mycobacterium tuberculosis (Mtb) control during chronic but not acute TB. Mechanistically, we demonstrate that following Mtb infection, S100A8/A9 expression is required for upregulation of the integrin molecule CD11b specifically on neutrophils, mediating their accumulation during chronic TB disease. These findings are further substantiated by increased expression of S100A8 and S100A9 mRNA in whole blood in human TB progressors when compared to non-progressors, and rapidly decreased S100A8/A9 protein levels in the serum upon TB treatment. Furthermore, we demonstrate that S100A8/A9 serum levels along with chemokines are useful in distinguishing between ATB and asymptomatic Mtb-infected latent individuals. Thus, our results support targeting S100A8/A9 pathways as host-directed therapy for TB.
Authors
Ninecia R. Scott, Rosemary V. Swanson, Noor Al-Hammadi, Racquel Domingo-Gonzalez, Javier Rangel-Moreno, Belinda A. Kriel, Allison N. Bucsan, Shibali Das, Mushtaq Ahmed, Smriti Mehra, Puthayalai Treerat, Alfredo Cruz-Lagunas, Luis Jimenez-Alvarez, Marcela Muñoz-Torrico, Karen Bobadilla-Lozoya, Thomas Vogl, Gerhard Walzl, Nelita du Plessis, Deepak Kaushal, Thomas Scriba, Joaquin Zuñiga, Shabaana Khader
Abstract
PD-1 expression is a hallmark of both early antigen-specific T-cell activation and later chronic stimulation suggesting key roles in both naive T-cell priming and memory T-cell responses. Although important similarities exist between T cells and NK cells, there are critical differences reflecting their biology and functions. The putative role of PD-1 expression in NK cell immunoregulation has been controversial. Our objective was to comprehensively assess PD-1 expression on NK cells using multiple sources and readouts. Primary human tumor samples, ex vivo culturing, mouse tumors and viral models were all assessed using flow cytometry, qRT-PCR and RNA sequencing. We demonstrate that under multiple activating conditions, highly purified human and mouse NK cells consistently lack PD-1 expression despite the marked upregulation of other regulatory markers such as TIGIT. We further show that neither NK cells from T-cell deficient Rag2-/- mice nor from transgenic PD-1 reporter mice express PD-1 using tumor or viral infection models. Asialo-GM1 (ASGM1), a receptor commonly targeted for NK-specific depletion, was also expressed on activated T cells co-expressing PD-1 contributing to in vivo effects previously attributed to NK cells. These data have important implications when attempting to discern NK from T cell effects depending on the models used and whether PD-1 blockade will directly impact NK cell therapies.
Authors
Sean J. Judge, Cordelia Dunai, Ethan G. Aguilar, Sarah C. Vick, Ian R. Sturgill, Lam T. Khuat, Kevin M. Stoffel, Jonathan Van Dyke, Dan L. Longo, Morgan A. Darrow, Stephen K. Anderson, Bruce R. Blazar, Arta M. Monjazeb, Jonathan S. Serody, Robert J. Canter, William J. Murphy
Abstract
The precise mechanism leading to profound immunodeficiency of HIV-infected patients is still only partially understood. Here, we show that more than 80% of CD4 T cells from HIV-infected patients have morphological abnormalities. Their membranes exhibited numerous large abnormal membrane microdomains (aMMDs), which trap and inactivate physiological receptors, such as that for IL-7. In patient plasma, we identified phospholipase A2 group IB (PLA2G1B) as the key molecule responsible for the formation of aMMDs. At physiological concentrations, PLA2G1B synergized with the HIV gp41 envelope protein, which appears to be a driver that targets PLA2G1B to the CD4 T-cell surface. The PLA2G1B/gp41 pair induced CD4 T cell unresponsiveness (anergy). At high concentrations in vitro, PLA2G1B acted alone, independently of gp41, and inhibited the IL-2, IL-4, and IL-7 responses, as well as TCR-mediated activation and proliferation, of CD4 T cells. PLA2G1B also decreased CD4 T-cell survival in vitro, likely playing a role in CD4 lymphopenia in conjunction with its induced IL-7 receptor defects. The effects on CD4 T-cell anergy could be blocked by a PLA2G1B-specific neutralizing mAb in vitro and in vivo. The PLA2G1B/gp41 pair constitutes a new mechanism of immune dysfunction and a compelling target for boosting immune responses in HIV-infected patients.
Authors
Julien Pothlichet, Thierry Rose, Florence Bugault, Louise Jeammet, Annalisa Meola, Ahmed Haouz, Frederick Saul, David Geny, José Alcami, Ezequiel Ruiz-Mateos Carmona, Luc Teyton, Gérard Lambeau, Jacques Thèze
Abstract
The molecular mechanisms responsible for the high immunosuppressive capacity of CD4+ regulatory T cells (Tregs) in tumors are poorly known. High-dimensional single cell profiling of T cells from chemotherapy-naïve individuals with non-small cell lung cancer identified the transcription factor IRF4 as specifically expressed by a subset of intratumoral CD4+ effector Tregs with superior suppressive activity. In contrast to the IRF4– counterparts, IRF4+ Tregs expressed a vast array of suppressive molecules, and their presence correlated with multiple exhausted subpopulations of T cells. Integration of transcriptomic and epigenomic data revealed that IRF4, either alone or in combination with its partner BATF, directly controlled a molecular program responsible for immunosuppression in tumors. Accordingly, deletion of Irf4 exclusively in Tregs resulted in delayed tumor growth in mice while the abundance of IRF4+ Tregs correlated with poor prognosis in patients with multiple human cancers. Thus, a common mechanism underlies immunosuppression in the tumor microenvironment irrespectively of the tumor type.
Authors
Giorgia Alvisi, Jolanda Brummelman, Simone Puccio, Emilia Maria Cristina Mazza, Elisa Paoluzzi Tomada, Agnese Losurdo, Veronica Zanon, Clelia Peano, Federico S. Colombo, Alice Scarpa, Marco Alloisio, Ajithkumar Vasanthakumar, Rahul Roychoudhuri, Marinos Kallikourdis, Massimiliano Pagani, Egesta Lopci, Pierluigi Novellis, Jonas Blume, Axel Kallies, Giulia Veronesi, Enrico Lugli
Abstract
Mycobacterium tuberculosis (Mtb) has co-evolved with humans for millennia and developed multiple mechanisms to evade host immunity. Restoring host immunity in order to improve outcomes and potentially shorten existing therapy will require identifying the full complement by which host immunity is inhibited. Perturbing host DNA methylation is a mechanism induced by chronic infections such as HIV, HPV, LCMV and schistosomiasis to evade host immunity. Here, we evaluated the DNA methylation status of TB patients and their asymptomatic household contacts demonstrating that TB patients have DNA hyper-methylation of the IL-2-STAT5, TNF-NF-ϰB and IFN-γ signaling pathways. By MSRE-qPCR, multiple genes of the IL-12-IFN-γ signaling pathway (IL12B, IL12RB2, TYK2, IFNGR1, JAK1 and JAK2) were hyper-methylated in TB patients. The DNA hyper-methylation of these pathways is associated with decreased immune responsiveness with decreased mitogen-induced upregulation of IFN-γ, TNF, IL-6, CXCL9, CXCL10 and IL-1β production. The DNA hyper-methylation of the IL-12-IFN-γ pathway was associated with decreased IFN-γ induced gene expression and decreased IL-12 inducible up-regulation of IFN-γ. This work demonstrates that immune cells from TB patients are characterized by DNA hyper-methylation of genes critical to mycobacterial immunity resulting in decreased mycobacteria-specific and non-specific immune responsiveness.
Authors
Andrew DiNardo, Kimal Rajapakshe, Tomoki Nishiguchi, Godwin Mtetwa, Sandra L. Grimm, Qiniso Dlamini, Jaquiline Kahari, Sanjana Mahapatra, Alexander W. Kay, Gugu Maphalala, Emily M. Mace, George Makedonas, Jeffrey D. Cirillo, Mihai Netea, Reinout van Crevel, Cristian Coarfa, Anna M. Mandalakas
Abstract
The mechanisms underlying rapid elimination of herpes simplex virus-2 (HSV-2) in the human genital tract despite low tissue-resident CD8+ and CD4+ T-cell density (TRM) are unknown. We analyzed shedding episodes during chronic HSV-2 infection: viral clearance always predominated within 24 hours of detection even if viral load exceeded 107 HSV DNA copies; surges in granzyme B and interferon-γ occurred within the early hours after reactivation and correlated with local viral load. We next developed an agent-based mathematical model of an HSV-2 genital ulcer to integrate mechanistic observations of TRM in situ proliferation, trafficking, cytolytic effects and cytokine alarm signaling from murine studies with viral kinetics, histopathology and lesion size data from humans. A sufficiently high density of HSV-2 specific TRM predicted rapid elimination of infected cells, but our data suggest that such TRM densities are relatively uncommon in infected tissues. At lower, more commonly observed TRM densities, TRM must initiate a rapidly diffusing, polyfunctional cytokine response with activation of bystander T cells in order to eliminate a majority of infected cells and eradicate briskly spreading HSV-2 infection.
Authors
Pavitra Roychoudhury, David A. Swan, Elizabeth R. Duke, Lawrence Corey, Jia Zhu, Veronica A. Davé, Laura E. Richert-Spuhler, Jennifer M. Lund, Martin Prlic, Joshua T. Schiffer
Copyright © 2020 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)