Research Article
Abstract
IFN-β, a type I IFN, is widely used for the treatment of MS. However, the mechanisms behind its therapeutic efficacy are not well understood. Using a murine model of MS, EAE, we demonstrate that the Th17-mediated development of autoimmune disease is constrained by Toll–IL-1 receptor domain–containing adaptor inducing IFN-β–dependent (TRIF-dependent) type I IFN production and its downstream signaling pathway. Mice with defects in TRIF or type I IFN receptor (IFNAR) developed more severe EAE. Notably, these mice exhibited marked CNS inflammation, as manifested by increased IL-17 production. In addition, IFNAR-dependent signaling events were essential for negatively regulating Th17 development. Finally, IFN-β–mediated IL-27 production by innate immune cells was critical for the immunoregulatory role of IFN-β in the CNS autoimmune disease. Together, our findings not only may provide a molecular mechanism for the clinical benefits of IFN-β in MS but also demonstrate a regulatory role for type I IFN induction and its downstream signaling pathways in limiting Th17 development and autoimmune inflammation.
Authors
Beichu Guo, Elmer Y. Chang, Genhong Cheng
Abstract
In the liver, the JNK cascade is induced downstream of TNF receptors (TNFRs) in response to inflammatory, microbial, and toxic challenges. Sustained activation of JNK triggers programmed cell death (PCD), and hepatocyte survival during these challenges requires induction of the NF-κB pathway, which antagonizes this activation by upregulating target genes. Thus, modulation of JNK activity is crucial to the liver response to TNFR-mediated challenge. The basis for this modulation, however, is unknown. Here, we investigated the role of the NF-κB target Gadd45b in the regulation of hepatocyte fate during liver regeneration after partial hepatectomy. We generated Gadd45b–/– mice and found that they exhibited decreased hepatocyte proliferation and increased PCD during liver regeneration. Notably, JNK activity was markedly increased and sustained in livers of Gadd45b–/– mice compared with control animals after partial hepatectomy. Furthermore, imposition of a Jnk2-null mutation, attenuating JNK activity, completely rescued the regenerative response in Gadd45b–/– mice. Interestingly, Gadd45β ablation did not affect hepatotoxic JNK signaling after a TNFR-mediated immune challenge, suggesting specificity in the inducible hepatic program for JNK restraint activated during distinct TNFR-mediated challenges. These data provide a basis for JNK suppression during liver regeneration and identify Gadd45β as a potential therapeutic target in liver diseases.
Authors
Salvatore Papa, Francesca Zazzeroni, Yang-Xin Fu, Concetta Bubici, Kellean Alvarez, Kathryn Dean, Peter A. Christiansen, Robert A. Anders, Guido Franzoso
Abstract
Osteoclastogenesis is a tightly regulated biological process, and deregulation can lead to severe bone disorders such as osteoporosis. The regulation of osteoclastic signaling is incompletely understood, but ubiquitination of TNF receptor–associated factor 6 (TRAF6) has recently been shown to be important in mediating this process. We therefore investigated the role of the recently identified deubiquitinating enzyme CYLD in osteoclastogenesis and found that mice with a genetic deficiency of CYLD had aberrant osteoclast differentiation and developed severe osteoporosis. Cultured osteoclast precursors derived from CYLD-deficient mice were hyperresponsive to RANKL-induced differentiation and produced more and larger osteoclasts than did controls upon stimulation. We assessed the expression pattern of CYLD and found that it was drastically upregulated during RANKL-induced differentiation of preosteoclasts. Furthermore, CYLD negatively regulated RANK signaling by inhibiting TRAF6 ubiquitination and activation of downstream signaling events. Interestingly, we found that CYLD interacted physically with the signaling adaptor p62 and thereby was recruited to TRAF6. These findings establish CYLD as a crucial negative regulator of osteoclastogenesis and suggest its involvement in the p62/TRAF6 signaling axis.
Authors
Wei Jin, Mikyoung Chang, Emmanuel M. Paul, Geetha Babu, Andrew J. Lee, William Reiley, Ato Wright, Minying Zhang, Jun You, Shao-Cong Sun
Abstract
Normal food intake and body weight homeostasis require the direct action of leptin on hypothalamic proopiomelanocortin (POMC) neurons. It has been proposed that leptin action requires PI3K activity. We therefore assessed the contribution of PI3K signaling to leptin’s effects on POMC neurons and organismal energy balance. Leptin caused a rapid depolarization of POMC neurons and an increase in action potential frequency in patch-clamp recordings of hypothalamic slices. Pharmacologic inhibition of PI3K prevented this depolarization and increased POMC firing rate, indicating a PI3K-dependent mechanism of leptin action. Mice with genetically disrupted PI3K signaling in POMC cells failed to undergo POMC depolarization or increased firing frequency in response to leptin. Insulin’s ability to hyperpolarize POMC neurons was also abolished in these mice. Moreover, targeted disruption of PI3K blunted the suppression of feeding elicited by central leptin administration. Despite these differences, mice with impaired PI3K signaling in POMC neurons exhibited normal long-term body weight regulation. Collectively, these results suggest that PI3K signaling in POMC neurons is essential for leptin-induced activation and insulin-induced inhibition of POMC cells and for the acute suppression of food intake elicited by leptin, but is not a major contributor to the regulation of long-term organismal energy homeostasis.
Authors
Jennifer W. Hill, Kevin W. Williams, Chianping Ye, Ji Luo, Nina Balthasar, Roberto Coppari, Michael A. Cowley, Lewis C. Cantley, Bradford B. Lowell, Joel K. Elmquist
Abstract
Dystrophic epidermolysis bullosa (DEB) is a severe skin fragility disorder associated with trauma-induced blistering, progressive soft tissue scarring, and increased risk of skin cancer. DEB is caused by mutations in type VII collagen. In this study, we describe the generation of a collagen VII hypomorphic mouse that serves as an immunocompetent animal model for DEB. These mice expressed collagen VII at about 10% of normal levels, and their phenotype closely resembled characteristics of severe human DEB, including mucocutaneous blistering, nail dystrophy, and mitten deformities of the extremities. The oral blistering experienced by these mice resulted in growth retardation, and repeated blistering led to excessive induction of tissue repair, causing TGF-β1–mediated contractile fibrosis generated by myofibroblasts and pseudosyndactyly in the extremities. Intradermal injection of WT fibroblasts resulted in neodeposition of collagen VII and functional restoration of the dermal-epidermal junction. Treated areas were also resistant to induced frictional stress. In contrast, untreated areas of the same mouse showed dermal-epidermal separation following induced stress. These data demonstrate that fibroblast-based treatment can be used to treat DEB in a mouse model and suggest that this approach may be effective in the development of clinical therapeutic regimens for patients with DEB.
Authors
Anja Fritsch, Stefan Loeckermann, Johannes S. Kern, Attila Braun, Michael R. Bösl, Thorsten A. Bley, Hauke Schumann, Dominik von Elverfeldt, Dominik Paul, Miriam Erlacher, Dirk Berens von Rautenfeld, Ingrid Hausser, Reinhard Fässler, Leena Bruckner-Tuderman
Abstract
Patients with sickle-cell disease (SCD) suffer from tissue damage and life-threatening complications caused by vasoocclusive crisis (VOC). Endothelin receptors (ETRs) are mediators of one of the most potent vasoconstrictor pathways in mammals, but the relationship between vasoconstriction and VOC is not well understood. We report here that pharmacological inhibition of ETRs prevented hypoxia-induced acute VOC and organ damage in a mouse model of SCD. An in vivo ultrasonographic study of renal hemodynamics showed a substantial increase in endothelin-mediated vascular resistance during hypoxia/reoxygenation-induced VOC. This increase was reversed by administration of the dual ETR antagonist (ETRA) bosentan, which had pleiotropic beneficial effects in vivo. It prevented renal and pulmonary microvascular congestion, systemic inflammation, dense rbc formation, and infiltration of activated neutrophils into tissues with subsequent nitrative stress. Bosentan also prevented death of sickle-cell mice exposed to a severe hypoxic challenge. These findings in mice suggest that ETRA could be a potential new therapy for SCD, as it may prevent acute VOC and limit organ damage in sickle-cell patients.
Authors
Nathalie Sabaa, Lucia de Franceschi, Philippe Bonnin, Yves Castier, Giorgio Malpeli, Haythem Debbabi, Ariane Galaup, Micheline Maier-Redelsperger, Sophie Vandermeersch, Aldo Scarpa, Anne Janin, Bernard Levy, Robert Girot, Yves Beuzard, Christophe Leboeuf, Annie Henri, Stéphane Germain, Jean-Claude Dussaule, Pierre-Louis Tharaux
Abstract
Loss-of-function mutations in bone morphogenetic protein receptor II (BMP-RII) are linked to pulmonary arterial hypertension (PAH); the ligand for BMP-RII, BMP-2, is a negative regulator of SMC growth. Here, we report an interplay between PPARγ and its transcriptional target apoE downstream of BMP-2 signaling. BMP-2/BMP-RII signaling prevented PDGF-BB–induced proliferation of human and murine pulmonary artery SMCs (PASMCs) by decreasing nuclear phospho-ERK and inducing DNA binding of PPARγ that is independent of Smad1/5/8 phosphorylation. Both BMP-2 and a PPARγ agonist stimulated production and secretion of apoE by SMCs. Using a variety of methods, including short hairpin RNAi in human PASMCs, PAH patient–derived BMP-RII mutant PASMCs, a PPARγ antagonist, and PASMCs isolated from PPARγ- and apoE-deficient mice, we demonstrated that the antiproliferative effect of BMP-2 was BMP-RII, PPARγ, and apoE dependent. Furthermore, we created mice with targeted deletion of PPARγ in SMCs and showed that they spontaneously developed PAH, as indicated by elevated RV systolic pressure, RV hypertrophy, and increased muscularization of the distal pulmonary arteries. Thus, PPARγ-mediated events could protect against PAH, and PPARγ agonists may reverse PAH in patients with or without BMP-RII dysfunction.
Authors
Georg Hansmann, Vinicio A. de Jesus Perez, Tero-Pekka Alastalo, Cristina M. Alvira, Christophe Guignabert, Janine M. Bekker, Stefan Schellong, Takashi Urashima, Lingli Wang, Nicholas W. Morrell, Marlene Rabinovitch
Abstract
CTLs have the potential to attack tumors, and adoptive transfer of CTLs can lead to tumor regression in mouse models and human clinical settings. However, the dynamics of tumor cell elimination during efficient T cell therapy is unknown, and it is unclear whether CTLs act directly by destroying tumor cells or indirectly by initiating the recruitment of innate immune cells that mediate tumor damage. To address these questions, we report real-time imaging of tumor cell apoptosis in vivo using intravital 2-photon microscopy and a Förster resonance energy transfer–based (FRET-based) reporter of caspase 3 activity. In a mouse model of solid tumor, we found that tumor regression after transfer of in vitro–activated CTLs occurred primarily through the direct action of CTLs on each individual tumor cell, with a minimal bystander effect. Surprisingly, the killing of 1 target cell by an individual CTL took an extended period of time, 6 hours on average, which suggested that the slow rate of killing intrinsically limits the efficiency of antitumor T cell responses. The ability to visualize when, where, and how tumor cells are killed in vivo offers new perspectives for understanding how immune effectors survey cancer cells and how local tumor microenvironments may subvert immune responses.
Authors
Béatrice Breart, Fabrice Lemaître, Susanna Celli, Philippe Bousso
Abstract
Retroviral vector–mediated HSC gene therapy has been used to treat individuals with a number of life-threatening diseases. However, some patients with SCID-X1 developed retroviral vector–mediated leukemia after treatment. The selective growth advantage of gene-modified cells in patients with SCID-X1 suggests that the transgene may have played a role in leukemogenesis. Here we report that 2 of 2 dogs and 1 of 2 macaques developed myeloid leukemia approximately 2 years after being transplanted with cells that overexpressed homeobox B4 (HOXB4) and cells transduced with a control gammaretroviral vector that did not express HOXB4. The leukemic cells had dysregulated expression of oncogenes, a block in myeloid differentiation, and overexpression of HOXB4. HOXB4 knockdown restored differentiation in leukemic cells, suggesting involvement of HOXB4. In contrast, leukemia did not arise from the cells carrying the control gammaretroviral vector. In addition, leukemia did not arise in 5 animals with high-level marking and polyclonal long-term repopulation following transplantation with cells transduced with an identical gammaretrovirus vector backbone expressing methylguanine methyltransferase. These findings, combined with the absence of leukemia in many other large animals transplanted with cells transduced with gammaretroviral vectors expressing genes other than HOXB4, show that HOXB4 overexpression poses a significant risk of leukemogenesis. Our data thus suggest the continued need for caution in genetic manipulation of repopulating cells, particularly when the transgene might impart an intrinsic growth advantage.
Authors
Xiao-Bing Zhang, Brian C. Beard, Grant D. Trobridge, Brent L. Wood, George E. Sale, Reeteka Sud, R. Keith Humphries, Hans-Peter Kiem
Abstract
Nontyphoidal strains of Salmonella (NTS) are a common cause of bacteremia among African children. Cell-mediated immune responses control intracellular infection, but they do not protect against extracellular growth of NTS in the blood. We investigated whether antibody protects against NTS bacteremia in Malawian children, because we found this condition mainly occurs before 2 years of age, with relative sparing of infants younger than 4 months old. Sera from all healthy Malawian children tested aged more than 16 months contained anti-Salmonella antibody and successfully killed NTS. Killing was mediated by complement membrane attack complex and not augmented in the presence of blood leukocytes. Sera from most healthy children less than 16 months old lacked NTS-specific antibody, and sera lacking antibody did not kill NTS despite normal complement function. Addition of Salmonella-specific antibody, but not mannose-binding lectin, enabled NTS killing. All NTS strains tested had long-chain lipopolysaccharide and the rck gene, features that resist direct complement-mediated killing. Disruption of lipopolysaccharide biosynthesis enabled killing of NTS by serum lacking Salmonella-specific antibody. We conclude that Salmonella-specific antibody that overcomes the complement resistance of NTS develops by 2 years of life in Malawian children. This finding and the age-incidence of NTS bacteremia suggest that antibody protects against NTS bacteremia and support the development of vaccines against NTS that induce protective antibody.
Authors
Calman A. MacLennan, Esther N. Gondwe, Chisomo L. Msefula, Robert A. Kingsley, Nicholas R. Thomson, Sarah A. White, Margaret Goodall, Derek J. Pickard, Stephen M. Graham, Gordon Dougan, C. Anthony Hart, Malcolm E. Molyneux, Mark T. Drayson
No posts were found with this tag.
Copyright © 2026 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)