M2 macrophages, innate lymphoid type 2 cells (ILC2s), eosinophils, Tregs, and invariant NK T cells (iNKT cells) all help to control adipose tissue inflammation, while M1 macrophages, TNF, and other inflammatory cytokines drive inflammation and insulin resistance in obesity. Stromal cells regulate leukocyte responses in lymph nodes, but the role of stromal cells in adipose tissue inflammation is unknown. PDGFRα+ stromal cells are major producers of IL-33 in adipose tissue. Here, we show that mesenchymal cadherin-11 modulates stromal fibroblast function. Cadherin-11–deficient mice displayed increased stromal production of IL-33, with concomitant enhancements in ILC2s and M2 macrophages that helped control adipose tissue inflammation. Higher expression levels of IL-33 in cadherin-11–deficient mice mediated ILC2 activation, resulting in higher IL-13 expression levels and M2 macrophage expansion in adipose tissue. Consistent with reduced adipose tissue inflammation, cadherin-11–deficient mice were protected from obesity-induced glucose intolerance and adipose tissue fibrosis. Importantly, anti–cadherin-11 mAb blockade similarly improved inflammation and glycemic control in obese WT mice. These results suggest that stromal fibroblasts expressing cadherin-11 regulate adipose tissue inflammation and thus highlight cadherin-11 as a potential therapeutic target for the management of obesity.
Sook Kyung Chang, Ayano C. Kohlgruber, Fumitaka Mizoguchi, Xavier Michelet, Benjamin J. Wolf, Kevin Wei, Pui Y. Lee, Lydia Lynch, Danielle Duquette, Victòria Ceperuelo-Mallafré, Alexander S. Banks, Michael B. Brenner
Asthma is associated with exposure to a wide variety of allergens and adjuvants. The extent to which overlap exists between the cellular and molecular mechanisms triggered by these various agents is poorly understood, but it might explain the differential responsiveness of patients to specific therapies. In particular, it is unclear why some, but not all, patients benefit from blockade of TNF. Here, we characterized signaling pathways triggered by distinct types of adjuvants during allergic sensitization. Mice sensitized to an innocuous protein using TLR ligands or house dust extracts as adjuvants developed mixed eosinophilic and neutrophilic airway inflammation and airway hyperresponsiveness (AHR) following allergen challenge, whereas mice sensitized using proteases as adjuvants developed predominantly eosinophilic inflammation and AHR. TLR ligands, but not proteases, induced TNF during allergic sensitization. TNF signaled through airway epithelial cells to reprogram them and promote Th2, but not Th17, development in lymph nodes. TNF was also required during the allergen challenge phase for neutrophilic and eosinophilic inflammation. In contrast, TNF was dispensable for allergic airway disease in a protease-mediated model of asthma. These findings might help to explain why TNF blockade improves lung function in only some patients with asthma.
Gregory S. Whitehead, Seddon Y. Thomas, Karim H. Shalaby, Keiko Nakano, Timothy P. Moran, James M. Ward, Gordon P. Flake, Hideki Nakano, Donald N. Cook
Obesity promotes a chronic inflammatory and hypercoagulable state that drives cardiovascular disease, type 2 diabetes, fatty liver disease, and several cancers. Elevated thrombin activity underlies obesity-linked thromboembolic events, but the mechanistic links between the thrombin/fibrin(ogen) axis and obesity-associated pathologies are incompletely understood. In this work, immunohistochemical studies identified extravascular fibrin deposits within white adipose tissue and liver as distinct features of mice fed a high-fat diet (HFD) as well as obese patients. Fibγ390–396A mice carrying a mutant form of fibrinogen incapable of binding leukocyte αMβ2-integrin were protected from HFD-induced weight gain and elevated adiposity. Fibγ390–396A mice had markedly diminished systemic, adipose, and hepatic inflammation with reduced macrophage counts within white adipose tissue, as well as near-complete protection from development of fatty liver disease and glucose dysmetabolism. Homozygous thrombomodulin-mutant ThbdPro mice, which have elevated thrombin procoagulant function, gained more weight and developed exacerbated fatty liver disease when fed a HFD compared with WT mice. In contrast, treatment with dabigatran, a direct thrombin inhibitor, limited HFD-induced obesity development and suppressed progression of sequelae in mice with established obesity. Collectively, these data provide proof of concept that targeting thrombin or fibrin(ogen) may limit pathologies in obese patients.
Anna K. Kopec, Sara R. Abrahams, Sherry Thornton, Joseph S. Palumbo, Eric S. Mullins, Senad Divanovic, Hartmut Weiler, A. Phillip Owens III, Nigel Mackman, Ashley Goss, Joanne van Ryn, James P. Luyendyk, Matthew J. Flick
Proinflammatory leukotrienes (LTs) are produced by 5-lipoxygenase (5-LO) aided by 5-LO–activating protein (FLAP). LT biosynthesis inhibitors are currently under clinical investigation as treatments for respiratory and cardiovascular diseases. Here, we have revealed a sex bias in the efficiency of clinically relevant LT biosynthesis inhibitors, showing that their effects are superior in females. We found that androgens cause these sex differences by impeding the LT-biosynthetic 5-LO/FLAP complex assembly. Lower doses of the FLAP inhibitor MK886 were required to reduce LTB4 levels in exudates of female versus male mice and rats. Following platelet-activating factor–induced shock, MK886 increased survival exclusively in female mice, and this effect was abolished by testosterone administration. FLAP inhibitors and the novel-type 5-LO inhibitors licofelone and sulindac sulfide exhibited higher potencies in human blood from females, and bioactive 5-LO/FLAP complexes were formed in female, but not male, human and murine leukocytes. Supplementation of female blood or leukocytes with 5α-dihydrotestosterone abolished the observed sex differences. Our data suggest that females may benefit from anti-LT therapy to a greater extent than males, prompting consideration of sex issues in LT modifier development.
Simona Pace, Carlo Pergola, Friederike Dehm, Antonietta Rossi, Jana Gerstmeier, Fabiana Troisi, Helmut Pein, Anja M. Schaible, Christina Weinigel, Silke Rummler, Hinnak Northoff, Stefan Laufer, Thorsten J. Maier, Olof Rådmark, Bengt Samuelsson, Andreas Koeberle, Lidia Sautebin, Oliver Werz
The mechanisms that regulate cell death and inflammation play an important role in liver disease and cancer. Receptor-interacting protein kinase 1 (RIPK1) induces apoptosis and necroptosis via kinase-dependent mechanisms and exhibits kinase-independent prosurvival and proinflammatory functions. Here, we have used genetic mouse models to study the role of RIPK1 in liver homeostasis, injury, and cancer. While ablating either RIPK1 or RelA in liver parenchymal cells (LPCs) did not cause spontaneous liver pathology, mice with combined deficiency of RIPK1 and RelA in LPCs showed increased hepatocyte apoptosis and developed spontaneous chronic liver disease and cancer that were independent of TNF receptor 1 (TNFR1) signaling. In contrast, mice with LPC-specific knockout of Ripk1 showed reduced diethylnitrosamine-induced (DEN-induced) liver tumorigenesis that correlated with increased DEN-induced hepatocyte apoptosis. Lack of RIPK1 kinase activity did not inhibit DEN-induced liver tumor formation, showing that kinase-independent functions of RIPK1 promote DEN-induced hepatocarcinogenesis. Moreover, mice lacking both RIPK1 and TNFR1 in LPCs displayed normal tumor formation in response to DEN, demonstrating that RIPK1 deficiency decreases DEN-induced liver tumor formation in a TNFR1-dependent manner. Therefore, these findings indicate that RIPK1 cooperates with NF-κB signaling to prevent TNFR1-independent hepatocyte apoptosis and the development of chronic liver disease and cancer, but acts downstream of TNFR1 signaling to promote DEN-induced liver tumorigenesis.
Trieu-My Van, Apostolos Polykratis, Beate Katharina Straub, Vangelis Kondylis, Nikoletta Papadopoulou, Manolis Pasparakis
The quantity and activation state of adipose tissue macrophages (ATMs) impact the development of obesity-induced metabolic diseases. Appetite-controlling hormones play key roles in obesity; however, our understanding of their effects on ATMs is limited. Here, we have shown that human and mouse ATMs express NPFFR2, a receptor for the appetite-reducing neuropeptide FF (NPFF), and that NPFFR2 expression is upregulated by IL-4, an M2-polarizing cytokine. Plasma levels of NPFF decreased in obese patients and high-fat diet–fed mice and increased following caloric restriction. NPFF promoted M2 activation and increased the proliferation of murine and human ATMs. Both M2 activation and increased ATM proliferation were abolished in NPFFR2-deficient ATMs. Mechanistically, the effects of NPFF involved the suppression of E3 ubiquitin ligase RNF128 expression, resulting in enhanced stability of phosphorylated STAT6 and increased transcription of the M2 macrophage–associated genes IL-4 receptor α (Il4ra), arginase 1 (Arg1), IL-10 (Il10), and alkylglycerol monooxygenase (Agmo). NPFF induced ATM proliferation concomitantly with the increase in N-Myc downstream-regulated gene 2 (Ndrg2) expression and suppressed the transcription of Ifi200 cell-cycle inhibitor family members and MAF bZIP transcription factor B (Mafb), a negative regulator of macrophage proliferation. NPFF thus plays an important role in supporting healthy adipose tissue via the maintenance of metabolically beneficial ATMs.
Syed F. Hassnain Waqas, Anh Cuong Hoang, Ya-Tin Lin, Grace Ampem, Hind Azegrouz, Lajos Balogh, Julianna Thuróczy, Jin-Chung Chen, Ivan C. Gerling, Sorim Nam, Jong-Seok Lim, Juncal Martinez-Ibañez, José T. Real, Stephan Paschke, Raphaëlle Quillet, Safia Ayachi, Frédéric Simonin, E. Marion Schneider, Jacqueline A. Brinkman, Dudley W. Lamming, Christine M. Seroogy, Tamás Röszer
Platelets play a critical role in atherogenesis and thrombosis-mediated myocardial ischemia, processes that are accelerated in diabetes. Whether hyperglycemia promotes platelet production and whether enhanced platelet production contributes to enhanced atherothrombosis remains unknown. Here we found that in response to hyperglycemia, neutrophil-derived S100 calcium-binding proteins A8/A9 (S100A8/A9) interact with the receptor for advanced glycation end products (RAGE) on hepatic Kupffer cells, resulting in increased production of IL-6, a pleiotropic cytokine that is implicated in inflammatory thrombocytosis. IL-6 acts on hepatocytes to enhance the production of thrombopoietin, which in turn interacts with its cognate receptor c-MPL on megakaryocytes and bone marrow progenitor cells to promote their expansion and proliferation, resulting in reticulated thrombocytosis. Lowering blood glucose using a sodium-glucose cotransporter 2 inhibitor (dapagliflozin), depleting neutrophils or Kupffer cells, or inhibiting S100A8/A9 binding to RAGE (using paquinimod), all reduced diabetes-induced thrombocytosis. Inhibiting S100A8/A9 also decreased atherogenesis in diabetic mice. Finally, we found that patients with type 2 diabetes have reticulated thrombocytosis that correlates with glycated hemoglobin as well as increased plasma S100A8/A9 levels. These studies provide insights into the mechanisms that regulate platelet production and may aid in the development of strategies to improve on current antiplatelet therapies and to reduce cardiovascular disease risk in diabetes.
Michael J. Kraakman, Man K.S. Lee, Annas Al-Sharea, Dragana Dragoljevic, Tessa J. Barrett, Emilie Montenont, Debapriya Basu, Sarah Heywood, Helene L. Kammoun, Michelle Flynn, Alexandra Whillas, Nordin M.J. Hanssen, Mark A. Febbraio, Erik Westein, Edward A. Fisher, Jaye Chin-Dusting, Mark E. Cooper, Jeffrey S. Berger, Ira J. Goldberg, Prabhakara R. Nagareddy, Andrew J. Murphy
Tissue-resident immune cells play a key role in local and systemic immune responses. The liver, in particular, hosts a large number of invariant natural killer T (iNKT) cells, which are involved in diverse immune responses. However, the mechanisms that regulate survival and homeostasis of liver iNKT cells are poorly defined. Here we have found that liver iNKT cells constitutively express the costimulatory TNF superfamily receptor OX40 and that OX40 stimulation results in massive pyroptotic death of iNKT cells, characterized by the release of potent proinflammatory cytokines that induce liver injury. This OX40/NKT pyroptosis pathway also plays a key role in concanavalin A–induced murine hepatitis. Mechanistically, we demonstrated that liver iNKT cells express high levels of caspase 1 and that OX40 stimulation activates caspase 1 via TNF receptor–associated factor 6–mediated recruitment of the paracaspase MALT1. We also found that activation of caspase 1 in iNKT cells results in processing of pro–IL-1β to mature IL-1β as well as cleavage of the pyroptotic protein gasdermin D, which generates a membrane pore–forming fragment to produce pyroptotic cell death. Thus, our study has identified OX40 as a death receptor for iNKT cells and uncovered a molecular mechanism of pyroptotic cell death. These findings may have important clinical implications in the development of OX40-directed therapies.
Peixiang Lan, Yihui Fan, Yue Zhao, Xiaohua Lou, Howard P. Monsour, Xiaolong Zhang, Yongwon Choi, Yaling Dou, Naoto Ishii, Rafik M. Ghobrial, Xiang Xiao, Xian Chang Li
Proinflammatory cytokine overproduction and excessive cell death, coupled with impaired clearance of apoptotic cells, have been implicated as causes of failure to resolve gut inflammation in inflammatory bowel diseases. Here we have found that dendritic cells expressing the apoptotic cell–recognizing receptor CD300f play a crucial role in regulating gut inflammatory responses in a murine model of colonic inflammation. CD300f-deficient mice failed to resolve dextran sulfate sodium–induced colonic inflammation as a result of defects in dendritic cell function that were associated with abnormal accumulation of apoptotic cells in the gut. CD300f-deficient dendritic cells displayed hyperactive phagocytosis of apoptotic cells, which stimulated excessive TNF-α secretion predominantly from dendritic cells. This, in turn, induced secondary IFN-γ overproduction by colonic T cells, leading to prolonged gut inflammation. Our data highlight a previously unappreciated role for dendritic cells in controlling gut homeostasis and show that CD300f-dependent regulation of apoptotic cell uptake is essential for suppressing overactive dendritic cell–mediated inflammatory responses, thereby controlling the development of chronic gut inflammation.
Ha-Na Lee, Linjie Tian, Nicolas Bouladoux, Jacquice Davis, Mariam Quinones, Yasmine Belkaid, John E. Coligan, Konrad Krzewski
The growth factor receptor Kit is involved in hematopoietic and nonhematopoietic development. Mice bearing
Pierre Cunin, Loka R. Penke, Jonathan N. Thon, Paul A. Monach, Tatiana Jones, Margaret H. Chang, Mary M. Chen, Imene Melki, Steve Lacroix, Yoichiro Iwakura, Jerry Ware, Michael F. Gurish, Joseph E. Italiano, Eric Boilard, Peter A. Nigrovic
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