Research Article
Abstract
The two most common forms of inflammatory bowel disease (IBD), Crohn’s disease and ulcerative colitis, affect approximately 1 million people in the United States. Uncontrolled APC reactivity toward commensal bacteria is implicated in the pathogenesis of the disease. A number of functionally distinct APC populations exist in the mucosal lamina propria (LP) below the intestinal epithelium, but their relative contributions to inflammation remain unclear. Here, we demonstrate in mice important roles for the chemokine receptor CX3CR1 in maintaining LP macrophage populations, preventing translocation of commensal bacteria to mesenteric lymph nodes (mLNs), and limiting colitogenic Th17 responses. CX3CR1 was found to be expressed in resident LP macrophages (defined as CD11b+F4/80+) but not DCs (defined as CD11c+CD103+). LP macrophage frequency and number were decreased in two strains of CX3CR1-knockout mice and in mice deficient in the CX3CR1 ligand CX3CL1. All these knockout strains displayed markedly increased translocation of commensal bacteria to mLNs. Additionally, the severity of DSS-induced colitis was dramatically enhanced in the knockout mice as compared with controls. Disease severity could be limited by either administration of neutralizing IL-17A antibodies or transfer of CX3CR1-sufficient macrophages. Our data thus suggest key roles for the CX3CR1/CX3CL1 axis in the intestinal mucosa; further clarification of CX3CR1 function will likely direct efforts toward therapeutic intervention for mucosal inflammatory disorders such as IBD.
Authors
Oscar Medina-Contreras, Duke Geem, Oskar Laur, Ifor R. Williams, Sergio A. Lira, Asma Nusrat, Charles A. Parkos, Timothy L. Denning
Abstract
NF-κB–inducing kinase (NIK) is an essential upstream kinase in noncanonical NF-κB signaling. NIK-dependent NF-κB activation downstream of several TNF receptor family members mediates lymphoid organ development and B cell homeostasis. Peripheral T cell populations are normal in the absence of NIK, but the role of NIK during in vivo T cell responses to antigen has been obscured by other developmental defects in NIK-deficient mice. Here, we have identified a T cell–intrinsic requirement for NIK in graft-versus-host disease (GVHD), wherein NIK-deficient mouse T cells transferred into MHC class II mismatched recipients failed to cause GVHD. Although NIK was not necessary for antigen receptor signaling, it was absolutely required for costimulation through the TNF receptor family member OX40 (also known as CD134). When we conditionally overexpressed NIK in T cells, mice suffered rapid and fatal autoimmunity characterized by hyperactive effector T cells and poorly suppressive Foxp3+ Tregs. Together, these data illuminate a critical T cell–intrinsic role for NIK during immune responses and suggest that its tight regulation is critical for avoiding autoimmunity.
Authors
Susan E. Murray, Fanny Polesso, Alexander M. Rowe, Soumen Basak, Yoshinobu Koguchi, Katelynne Gardner Toren, Alexander Hoffmann, David C. Parker
Abstract
Hereditary sensory and autonomic neuropathy type 1 (HSAN1) causes sensory loss that predominantly affects the lower limbs, often preceded by hyperpathia and spontaneous shooting or lancinating pain. It is caused by several missense mutations in the genes encoding 2 of the 3 subunits of the enzyme serine palmitoyltransferase (SPT). The mutant forms of the enzyme show a shift from their canonical substrate l-serine to the alternative substrate l-alanine. This shift leads to increased formation of neurotoxic deoxysphingolipids (dSLs). Our initial analysis showed that in HEK cells transfected with SPTLC1 mutants, dSL generation was modulated in vitro in the presence of various amino acids. We therefore examined whether in vivo specific amino acid substrate supplementation influenced dSL levels and disease severity in HSAN1. In mice bearing a transgene expressing the C133W SPTLC1 mutant linked to HSAN1, a 10% l-serine–enriched diet reduced dSL levels. l-serine supplementation also improved measures of motor and sensory performance as well as measures of male fertility. In contrast, a 10% l-alanine–enriched diet increased dSL levels and led to severe peripheral neuropathy. In a pilot study with 14 HSAN1 patients, l-serine supplementation similarly reduced dSL levels. These observations support the hypothesis that an altered substrate selectivity of the mutant SPT is key to the pathophysiology of HSAN1 and raise the prospect of l-serine supplementation as a first treatment option for this disorder.
Authors
Kevin Garofalo, Anke Penno, Brian P. Schmidt, Ho-Joon Lee, Matthew P. Frosch, Arnold von Eckardstein, Robert H. Brown, Thorsten Hornemann, Florian S. Eichler
Abstract
Current therapies for non-Hodgkin lymphoma commonly include CD20 mAb to deplete tumor cells. However, the response is not durable in a substantial proportion of patients. Herein, we report our studies in mice testing the hypothesis that heterogeneity in endogenous tissue CD20+ B cell depletion influences in vivo lymphoma therapy. Using highly effective CD20 mAbs that efficiently deplete endogenous mature B cells and homologous CD20+ primary lymphoma cells through monocyte- and antibody-dependent mechanisms, we found that lymphoma depletion and survival were reduced when endogenous host B cells were not depleted, particularly a rare IL-10–producing B cell subset (B10 cells) known to regulate inflammation and autoimmunity. Even small numbers of adoptively transferred B10 cells dramatically suppressed CD20 mAb–mediated lymphoma depletion by inhibiting mAb-mediated monocyte activation and effector function through IL-10–dependent mechanisms. However, the activation of innate effector cells using a TLR3 agonist that did not activate B10 cells overcame the negative regulatory effects of endogenous B10 cells and enhanced lymphoma depletion during CD20 immunotherapy in vivo. Thus, we conclude that endogenous B10 cells are potent negative regulators of innate immunity, with even small numbers of residual B10 cells able to inhibit lymphoma depletion by CD20 mAbs. Consequently, B10 cell removal could provide a way to optimize CD20 mAb–mediated clearance of malignant B cells in patients with non-Hodgkin lymphoma.
Authors
Mayuka Horikawa, Veronique Minard-Colin, Takashi Matsushita, Thomas F. Tedder
Abstract
Wounds that fail to heal in a timely manner, for example, diabetic foot ulcers, pose a health, economic, and social problem worldwide. For decades, conventional wisdom has pointed to growth factors as the main driving force of wound healing; thus, growth factors have become the center of therapeutic developments. To date, becaplermin (recombinant human PDGF-BB) is the only US FDA-approved growth factor therapy, and it shows modest efficacy, is costly, and has the potential to cause cancer in patients. Other molecules that drive wound healing have therefore been sought. In this context, it has been noticed that wounds do not heal without the participation of secreted Hsp90α. Here, we report that a 115-aa fragment of secreted Hsp90α (F-5) acts as an unconventional wound healing agent in mice. Topical application of F-5 peptide promoted acute and diabetic wound closure in mice far more effectively than did PDGF-BB. The stronger effect of F-5 was due to 3 properties not held by conventional growth factors: its ability to recruit both epidermal and dermal cells; the fact that its ability to promote dermal cell migration was not inhibited by TGF-β; and its ability to override the inhibitory effects of hyperglycemia on cell migration in diabetes. The discovery of F-5 challenges the long-standing paradigm of wound healing factors and reveals a potentially more effective and safer agent for healing acute and diabetic wounds.
Authors
Chieh-Fang Cheng, Divya Sahu, Fred Tsen, Zhengwei Zhao, Jianhua Fan, Rosie Kim, Xinyi Wang, Kathryn O’Brien, Yong Li, Yuting Kuang, Mei Chen, David T. Woodley, Wei Li
Abstract
Fetal and neonatal immune thrombocytopenia (FNIT) is a severe bleeding disorder caused by maternal antibody–mediated destruction of fetal/neonatal platelets. It is the most common cause of severe thrombocytopenia in neonates, but the frequency of FNIT-related miscarriage is unknown, and the mechanism(s) underlying fetal mortality have not been explored. Furthermore, although platelet αIIbβ3 integrin and GPIbα are the major antibody targets in immune thrombocytopenia, the reported incidence of anti-GPIbα–mediated FNIT is rare. Here, we developed mouse models of FNIT mediated by antibodies specific for GPIbα and β3 integrin and compared their pathogenesis. We found, unexpectedly, that miscarriage occurred in the majority of pregnancies in our model of anti-GPIbα–mediated FNIT, which was far more frequent than in anti-β3–mediated FNIT. Dams with anti-GPIbα antibodies exhibited extensive fibrin deposition and apoptosis/necrosis in their placentas, which severely impaired placental function. Furthermore, anti-GPIbα (but not anti-β3) antiserum activated platelets and enhanced fibrin formation in vitro and thrombus formation in vivo. Importantly, treatment with either intravenous IgG or a monoclonal antibody specific for the neonatal Fc receptor efficiently prevented anti-GPIbα–mediated FNIT. Thus, the maternal immune response to fetal GPIbα causes what we believe to be a previously unidentified, nonclassical FNIT (i.e., spontaneous miscarriage but not neonatal bleeding) in mice. These results suggest that a similar pathology may have masked the severity and frequency of human anti-GPIbα–mediated FNIT, but also point to possible therapeutic interventions.
Authors
Conglei Li, Siavash Piran, Pingguo Chen, Sean Lang, Alessandro Zarpellon, Joseph W. Jin, Guangheng Zhu, Adili Reheman, Dianne E. van der Wal, Elisa K. Simpson, Ran Ni, Peter L. Gross, Jerry Ware, Zaverio M. Ruggeri, John Freedman, Heyu Ni
Abstract
Type 1 diabetes (T1D) is an autoimmune disease that shows familial aggregation in humans and likely has genetic determinants. Disease linkage studies have revealed many susceptibility loci for T1D in mice and humans. The mouse T1D susceptibility locus insulin-dependent diabetes susceptibility 3 (Idd3), which has a homologous genetic interval in humans, encodes cytokine genes Il2 and Il21 and regulates diabetes and other autoimmune diseases; however, the cellular and molecular mechanisms of this regulation are still being elucidated. Here we show that T cells from NOD mice produce more Il21 and less Il2 and exhibit enhanced Th17 cell generation compared with T cells from NOD.Idd3 congenic mice, which carry the protective Idd3 allele from a diabetes-resistant mouse strain. Further, APCs from NOD and NOD.Idd3 mice played a central role in this differential Th17 cell development, and IL-21 signaling in APCs was pivotal to this process. Specifically, NOD-derived APCs showed increased production of pro-Th17 mediators and dysregulation of the retinoic acid (RA) signaling pathway compared with APCs from NOD.Idd3 and NOD.Il21r-deficient mice. These data suggest that the protective effect of the Idd3 locus is due, in part, to differential RA signaling in APCs and that IL-21 likely plays a role in this process. Thus, we believe APCs provide a new candidate for therapeutic intervention in autoimmune diseases.
Authors
Sue M. Liu, David H. Lee, Jenna M. Sullivan, Denise Chung, Anneli Jäger, Bennett O.V. Shum, Nora E. Sarvetnick, Ana C. Anderson, Vijay K. Kuchroo
Abstract
Diabetes mellitus is associated with platelet hyperactivity, which leads to increased morbidity and mortality from cardiovascular disease. This is coupled with enhanced levels of thromboxane (TX), an eicosanoid that facilitates platelet aggregation. Although intensely studied, the mechanism underlying the relationship among hyperglycemia, TX generation, and platelet hyperactivity remains unclear. We sought to identify key signaling components that connect high levels of glucose to TX generation and to examine their clinical relevance. In human platelets, aldose reductase synergistically modulated platelet response to both hyperglycemia and collagen exposure through a pathway involving ROS/PLCγ2/PKC/p38α MAPK. In clinical patients with platelet activation (deep vein thrombosis; saphenous vein graft occlusion after coronary bypass surgery), and particularly those with diabetes, urinary levels of a major enzymatic metabolite of TX (11-dehydro-TXB2 [TX-M]) were substantially increased. Elevated TX-M persisted in diabetic patients taking low-dose aspirin (acetylsalicylic acid, ASA), suggesting that such patients may have underlying endothelial damage, collagen exposure, and thrombovascular disease. Thus, our study has identified multiple potential signaling targets for designing combination chemotherapies that could inhibit the synergistic activation of platelets by hyperglycemia and collagen exposure.
Authors
Wai Ho Tang, Jeremiah Stitham, Scott Gleim, Concetta Di Febbo, Ettore Porreca, Cristiano Fava, Stefania Tacconelli, Marta Capone, Virgilio Evangelista, Giacomo Levantesi, Li Wen, Kathleen Martin, Pietro Minuz, Jeffrey Rade, Paola Patrignani, John Hwa
Abstract
Systemic inflammatory response syndrome (SIRS) is a potentially lethal condition, as it can progress to shock, multi-organ failure, and death. It can be triggered by infection, tissue damage, or hemorrhage. The role of tissue injury in the progression from SIRS to shock is incompletely understood. Here, we show that treatment of mice with concanavalin A (ConA) to induce liver injury triggered a G-CSF–dependent hepatic infiltration of CD11b+Gr-1+Ly6G+Ly6C+ immature myeloid cells that expressed the orphan receptor myeloid DAP12–associated lectin–1 (MDL-1; also known as CLEC5A). Activation of MDL-1 using dengue virus or an agonist MDL-1–specific antibody in the ConA-treated mice resulted in shock. The MDL-1+ cells were pathogenic, and in vivo depletion of MDL-1+ cells provided protection. Triggering MDL-1 on these cells induced production of NO and TNF-α, which were found to be elevated in the serum of treated mice and required for MDL-1–induced shock. Surprisingly, MDL-1–induced NO and TNF-α production required eNOS but not iNOS. Activation of DAP12, DAP10, Syk, PI3K, and Akt was critical for MDL-1–induced shock. In addition, Akt physically interacted with and activated eNOS. Therefore, triggering of MDL-1 on immature myeloid cells and production of NO and TNF-α may play a critical role in the pathogenesis of shock. Targeting the MDL-1/Syk/PI3K/Akt/eNOS pathway represents a potential new therapeutic strategy to prevent the progression of SIRS to shock.
Authors
Ricky Cheung, Fran Shen, Joseph H. Phillips, Mandy J. McGeachy, Daniel J. Cua, Paul G. Heyworth, Robert H. Pierce
Abstract
TLRs are a family of receptors that mediate immune system pathogen recognition. In the respiratory system, TLR activation has both beneficial and deleterious effects in asthma. For example, clinical data indicate that TLR6 activation exerts protective effects in asthma. Here, we explored the mechanism or mechanisms through which TLR6 mediates this effect using mouse models of Aspergillus fumigatus–induced and house dust mite antigen–induced (HDM antigen–induced) chronic asthma. Tlr6–/– mice with fungal- or HDM antigen–induced asthma exhibited substantially increased airway hyperresponsiveness, inflammation, and remodeling compared with WT asthmatic groups. Surprisingly, whole-lung levels of IL-23 and IL-17 were markedly lower in Tlr6–/– versus WT asthmatic mice. Tlr6–/– DCs generated less IL-23 upon activation with lipopolysaccharide, zymosan, or curdlan. Impaired IL-23 generation in Tlr6–/– mice also corresponded with lower levels of expression of the pathogen-recognition receptor dectin-1 and expansion of Th17 cells both in vivo and in vitro. Exogenous IL-23 treatment of asthmatic Tlr6–/– mice restored IL-17A production and substantially reduced airway hyperresponsiveness, inflammation, and lung fungal burden compared with that in untreated asthmatic Tlr6–/– mice. Together, our data demonstrate that TLR6 activation is critical for IL-23 production and Th17 responses, which both regulate the allergic inflammatory response in chronic fungal-induced asthma. Thus, therapeutics targeting TLR6 activity might prove efficacious in the treatment of clinical asthma.
Authors
Ana Paula Moreira, Karen A. Cavassani, Ugur B. Ismailoglu, Rikki Hullinger, Michael P. Dunleavy, Darryl A. Knight, Steven L. Kunkel, Satoshi Uematsu, Shizuo Akira, Cory M. Hogaboam
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