Research Article
Abstract
EAE is a mouse T cell–mediated autoimmune disease of the CNS used to model the human condition MS. The contributions of B cells to EAE initiation and progression are unclear. In this study, we have shown that EAE disease initiation and progression are differentially influenced by the depletion of B cells from mice with otherwise intact immune systems. CD20 antibody–mediated B cell depletion before EAE induction substantially exacerbated disease symptoms and increased encephalitogenic T cell influx into the CNS. Increased symptom severity resulted from the depletion of a rare IL-10–producing CD1dhiCD5+ regulatory B cell subset (B10 cells), since the adoptive transfer of splenic B10 cells before EAE induction normalized EAE in B cell–depleted mice. While transfer of regulatory B10 cells was maximally effective during early EAE initiation, they had no obvious role during disease progression. Rather, B cell depletion during EAE disease progression dramatically suppressed symptoms. Specifically, B cells were required for the generation of CD4+ T cells specific for CNS autoantigen and the entry of encephalitogenic T cells into the CNS during disease progression. These results demonstrate reciprocal regulatory roles for B cells during EAE immunopathogenesis. The therapeutic effect of B cell depletion for the treatment of autoimmunity may therefore depend on the relative contributions and the timing of these opposing B cell activities during the course of disease initiation and pathogenesis.
Authors
Takashi Matsushita, Koichi Yanaba, Jean-David Bouaziz, Manabu Fujimoto, Thomas F. Tedder
Abstract
Glycogen synthase kinase–3 (GSK-3) is a widely expressed and highly conserved serine/threonine protein kinase encoded by 2 genes, GSK3A and GSK3B. GSK-3 is thought to be involved in tissue repair and fibrogenesis, but its role in these processes is currently unknown. To investigate the function of GSK-3β in fibroblasts, we generated mice harboring a fibroblast-specific deletion of Gsk3b and evaluated their wound-healing and fibrogenic responses. We have shown that Gsk3b-conditional-KO mice (Gsk3b-CKO mice) exhibited accelerated wound closure, increased fibrogenesis, and excessive scarring compared with control mice. In addition, Gsk3b-CKO mice showed elevated collagen production, decreased cell apoptosis, elevated levels of profibrotic α-SMA, and increased myofibroblast formation during wound healing. In cultured Gsk3b-CKO fibroblasts, adhesion, spreading, migration, and contraction were enhanced. Both Gsk3b-CKO mice and fibroblasts showed elevated expression and production of endothelin-1 (ET-1) compared with control mice and cells. Antagonizing ET-1 reversed the phenotype of Gsk3b-CKO fibroblasts and mice. Thus, GSK-3β appears to control the progression of wound healing and fibrosis by modulating ET-1 levels. These results suggest that targeting the GSK-3β pathway or ET-1 may be of benefit in controlling tissue repair and fibrogenic responses in vivo.
Authors
Mohit Kapoor, Shangxi Liu, Xu Shi-wen, Kun Huh, Matthew McCann, Christopher P. Denton, James R. Woodgett, David J. Abraham, Andrew Leask
Abstract
Asthma is a complex heritable disease that is increasing in prevalence and severity, particularly in developed countries such as the United States, where 11% of the population is affected. The contribution of environmental and genetic factors to this growing epidemic is currently not well understood. We developed the hypothesis, based on previous literature, that changes in DNA methylation resulting in aberrant gene transcription may enhance the risk of developing allergic airway disease. Our findings indicate that in mice, a maternal diet supplemented with methyl donors enhanced the severity of allergic airway disease that was inherited transgenerationally. Using a genomic approach, we discovered 82 gene-associated loci that were differentially methylated after in utero supplementation with a methyl-rich diet. These methylation changes were associated with decreased transcriptional activity and increased disease severity. Runt-related transcription factor 3 (Runx3), a gene known to negatively regulate allergic airway disease, was found to be excessively methylated, and Runx3 mRNA and protein levels were suppressed in progeny exposed in utero to a high-methylation diet. Moreover, treatment with a demethylating agent increased Runx3 gene transcription, further supporting our claim that a methyl-rich diet can affect methylation status and consequent transcriptional regulation. Our findings indicate that dietary factors can modify the heritable risk of allergic airway disease through epigenetic mechanisms during a vulnerable period of fetal development in mice.
Authors
John W. Hollingsworth, Shuichiro Maruoka, Kathy Boon, Stavros Garantziotis, Zhuowei Li, John Tomfohr, Nathaniel Bailey, Erin N. Potts, Gregory Whitehead, David M. Brass, David A. Schwartz
Abstract
The threat of avian influenza A (H5N1) infection in humans remains a global health concern. Current influenza vaccines stimulate antibody responses against the surface glycoproteins but are ineffective against strains that have undergone significant antigenic variation. An alternative approach is to stimulate pre-existing memory T cells established by seasonal human influenza A infection that could cross-react with H5N1 by targeting highly conserved internal proteins. To determine how common cross-reactive T cells are, we performed a comprehensive ex vivo analysis of cross-reactive CD4+ and CD8+ memory T cell responses to overlapping peptides spanning the full proteome of influenza A/Viet Nam/CL26/2005 (H5N1) and influenza A/New York/232/2004 (H3N2) in healthy individuals from the United Kingdom and Viet Nam. Memory CD4+ and CD8+ T cells isolated from the majority of participants exhibited human influenza–specific responses and showed cross-recognition of at least one H5N1 internal protein. Participant CD4+ and CD8+ T cells recognized multiple synthesized influenza peptides, including peptides from the H5N1 strain. Matrix protein 1 (M1) and nucleoprotein (NP) were the immunodominant targets of cross-recognition. In addition, cross-reactive CD4+ and CD8+ T cells recognized target cells infected with recombinant vaccinia viruses expressing either H5N1 M1 or NP. Thus, vaccine formulas inducing heterosubtypic T cell–mediated immunity may confer broad protection against avian and human influenza A viruses.
Authors
Laurel Yong-Hwa Lee, Do Lien Anh Ha, Cameron Simmons, Menno D. de Jong, Nguyen Van Vinh Chau, Reto Schumacher, Yan Chun Peng, Andrew J. McMichael, Jeremy J. Farrar, Geoffrey L. Smith, Alain R.M. Townsend, Brigitte A. Askonas, Sarah Rowland-Jones, Tao Dong
Abstract
Although acute lung injury contributes significantly to critical illness, resolution often occurs spontaneously via activation of incompletely understood pathways. We recently found that mechanical ventilation of mice increases the level of pulmonary adenosine, and that mice deficient for extracellular adenosine generation show increased pulmonary edema and inflammation after ventilator-induced lung injury (VILI). Here, we profiled the response to VILI in mice with genetic deletions of each of the 4 adenosine receptors (ARs) and found that deletion of the A2BAR gene was specifically associated with reduced survival time and increased pulmonary albumin leakage after injury. In WT mice, treatment with an A2BAR-selective antagonist resulted in enhanced pulmonary inflammation, edema, and attenuated gas exchange, while an A2BAR agonist attenuated VILI. In bone marrow–chimeric A2BAR mice, although the pulmonary inflammatory response involved A2BAR signaling from bone marrow–derived cells, A2BARs located on the lung tissue attenuated VILI-induced albumin leakage and pulmonary edema. Furthermore, measurement of alveolar fluid clearance (AFC) demonstrated that A2BAR signaling enhanced amiloride-sensitive fluid transport and elevation of pulmonary cAMP levels following VILI, suggesting that A2BAR agonist treatment protects by drying out the lungs. Similar enhancement of pulmonary cAMP and AFC were also observed after β-adrenergic stimulation, a pathway known to promote AFC. Taken together, these studies reveal a role for A2BAR signaling in attenuating VILI and implicate this receptor as a potential therapeutic target during acute lung injury.
Authors
Tobias Eckle, Almut Grenz, Stefanie Laucher, Holger K. Eltzschig
Abstract
In acute inflammation, infiltrating polymorphonuclear leukocytes (also known as PMNs) release preformed granule proteins having multitudinous effects on the surrounding environment. Here we present what we believe to be a novel role for PMN-derived proteins in bacterial phagocytosis by both human and murine macrophages. Exposure of macrophages to PMN secretion markedly enhanced phagocytosis of IgG-opsonized Staphylococcus aureus both in vitro and in murine models in vivo. PMN secretion activated macrophages, resulting in upregulation of the Fcγ receptors CD32 and CD64, which then mediated the enhanced phagocytosis of IgG-opsonized bacteria. The phagocytosis-stimulating activity within the PMN secretion was found to be due to proteins released from PMN primary granules; thorough investigation revealed heparin-binding protein (HBP) and human neutrophil peptides 1–3 (HNP1–3) as the mediators of the macrophage response to PMN secretion. The use of blocking antibodies and knockout mice revealed that HBP acts via β2 integrins, but the receptor for HNP1–3 remained unclear. Mechanistically, HBP and HNP1–3 triggered macrophage release of TNF-α and IFN-γ, which acted in an autocrine loop to enhance expression of CD32 and CD64 and thereby enhance phagocytosis. Thus, we attribute what may be a novel role for PMN granule proteins in regulating the immune response to bacterial infections.
Authors
Oliver Soehnlein, Ylva Kai-Larsen, Robert Frithiof, Ole E. Sorensen, Ellinor Kenne, Karin Scharffetter-Kochanek, Einar E. Eriksson, Heiko Herwald, Birgitta Agerberth, Lennart Lindbom
Abstract
Genital coinfections increase an individual’s risk of becoming infected with HIV-1 by sexual contact. Several mechanisms have been proposed to explain this, such as the presence of ulceration and bleeding caused by the coinfecting pathogen. Here we demonstrate that Langerhans cells (LCs) are involved in the increased susceptibility to HIV-1 in the presence of genital coinfections. Although LCs are a target for HIV-1 infection in genital tissues, we found that immature LCs did not efficiently mediate HIV-1 transmission in an ex vivo human skin explant model. However, the inflammatory stimuli TNF-α and Pam3CysSerLys4 (Pam3CSK4), the ligand for the TLR1/TLR2 heterodimer, strongly increased HIV-1 transmission by LCs through distinct mechanisms. TNF-α enhanced transmission by increasing HIV-1 replication in LCs, whereas Pam3CSK4 acted by increasing LC capture of HIV-1 and subsequent trans-infection of T cells. Genital infections such as Candida albicans and Neisseria gonorrhea not only triggered TLRs but also induced TNF-α production in vaginal and skin explants. Thus, during coinfection, LCs could be directly activated by pathogenic structures and indirectly activated by inflammatory factors, thereby increasing the risk of acquiring HIV-1. Our data demonstrate a decisive role for LCs in HIV-1 transmission during genital coinfections and suggest antiinflammatory therapies as potential strategies to prevent HIV-1 transmission.
Authors
Marein A.W.P. de Jong, Lot de Witte, Menno J. Oudhoff, Sonja I. Gringhuis, Philippe Gallay, Teunis B.H. Geijtenbeek
Abstract
Plasmacytoid DCs (pDCs) have been implicated as crucial cells in antiviral immune responses. On recognizing HIV, they become activated, secreting large amounts of IFN-α and inflammatory cytokines, thereby potentiating innate and adaptive antiviral immune responses. Here, we have shown that HIV-stimulated human pDCs can also induce the differentiation of naive CD4+ T cells into Tregs with suppressive function. This differentiation was independent of pDC production of IFN-α and primarily dependent on pDC expression of indoleamine 2,3-dioxygenase, which was induced through the TLR/MyD88 pathway, following binding of HIV to CD4 and triggering of TLR7 by HIV genomic RNA. Functionally, the Tregs induced by pDCs were shown to inhibit the maturation of bystander conventional DCs. This study therefore reveals what we believe to be a novel mechanism by which pDC may regulate and potentially limit anti-HIV immune responses.
Authors
Olivier Manches, David Munn, Anahita Fallahi, Jeffrey Lifson, Laurence Chaperot, Joel Plumas, Nina Bhardwaj
Abstract
The underlying molecular mechanisms that cause immune cells, mediators of our defense system, to promote tumor invasion and angiogenesis remain incompletely understood. Constitutively activated Stat3 in tumor cells has been shown to promote tumor invasion and angiogenesis. Therefore, we sought to determine whether Stat3 activation in tumor-associated inflammatory cells has a similar function. We found that Stat3 signaling mediates multidirectional crosstalk among tumor cells, myeloid cells in the tumor stroma, and ECs that contributes to tumor angiogenesis in mice. Myeloid-derived suppressor cells and macrophages isolated from mouse tumors displayed activated Stat3 and induced angiogenesis in an in vitro tube formation assay via Stat3 induction of angiogenic factors, including VEGF and bFGF. Stat3-regulated factors produced by both tumor cells and tumor-derived myeloid cells also induced constitutive activation of Stat3 in tumor endothelium, and inhibiting Stat3 in ECs substantially reduced in vitro tumor factor–induced endothelial migration and tube formation. In vivo assays demonstrated the requirement for Stat3 signaling in tumor-associated myeloid cells for tumor angiogenesis. Our results indicate that, by virtue of the ability of Stat3 in tumor cells and tumor-derived myeloid cells to upregulate expression of factors that activate Stat3 in ECs, Stat3 mediates multidirectional crosstalk among tumor cells, tumor-associated myeloid cells, and ECs that contributes to tumor angiogenesis.
Authors
Maciej Kujawski, Marcin Kortylewski, Heehyoung Lee, Andreas Herrmann, Heidi Kay, Hua Yu
Abstract
The integrity of the endothelial monolayer is essential to blood vessel homeostasis and active regulation of endothelial permeability. The FGF system plays important roles in a wide variety of physiologic and pathologic conditions; however, its role in the adult vasculature has not been defined. To assess the role of the FGF system in the adult endothelial monolayer, we disrupted FGF signaling in bovine aortic endothelial cells and human saphenous vein endothelial cells in vitro and in adult mouse and rat endothelial cells in vivo using soluble FGF traps or a dominant inhibitor of all FGF receptors. The inhibition of FGF signaling using these approaches resulted in dissociation of the VE-cadherin/p120-catenin complex and disassembly of adherens and tight junctions, which progressed to loss of endothelial cells, severe impairment of the endothelial barrier function, and finally, disintegration of the vasculature. Thus, FGF signaling plays a key role in the maintenance of vascular integrity.
Authors
Masahiro Murakami, Loc T. Nguyen, Zhen W. Zhang, Karen L. Moodie, Peter Carmeliet, Radu V. Stan, Michael Simons
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