Research Article
Abstract
Degeneration of the neuromuscular system is a characteristic feature of spinal and bulbar muscular atrophy (SBMA), a CAG/polyglutamine (polyQ) expansion disorder caused by mutation in the androgen receptor (AR). Using a gene-targeted mouse model of SBMA, AR113Q mice, we demonstrate age-dependent degeneration of the neuromuscular system that initially manifests with muscle weakness and atrophy and progresses to include denervation of neuromuscular junctions and lower motor neuron soma atrophy. Using this model, we tested the hypothesis that therapeutic intervention targeting skeletal muscle during this period of disease progression arrests degeneration of the neuromuscular system. To accomplish this, AR-targeted antisense oligonucleotides were administered subcutaneously to symptomatic AR113Q mice to reduce expression of polyQ AR in peripheral tissues but not in the spinal cord. This intervention rescued muscle atrophy, neuromuscular junction innervation, lower motor neuron soma size, and survival in aged AR113Q mice. Single-nucleus RNA sequencing revealed age-dependent transcriptional changes in the AR113Q spinal cord during disease progression, which were mitigated by peripheral AR gene silencing. Our findings underscore the intricate interplay between peripheral tissues and the central nervous system in SBMA and emphasize the therapeutic effectiveness of peripheral gene knockdown in symptomatic disease.
Authors
Changwoo Lee, Zhigang Yu, Curtis J. Kuo, Leon Tejwani, Rosalie M. Grijalva, Eunwoo Bae, Hien T. Zhao, Janghoo Lim, Andrew P. Lieberman
Abstract
Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome is a hemato-rheumatoid disease caused by somatic UBA1 mutations in hematopoietic stem cells (HSCs). The pathogenic cell type(s) responsible for the syndrome are unknown, and murine models recapitulating the disease are lacking. We report that loss of Uba1 in various mouse hematopoietic cell types resulted in pleiotropic consequences and demonstrate that an approximate 70% loss of Uba1 in neutrophils (NEs) of murine mutants induced nonlethal VEXAS-like symptoms. Depletion of Uba1 in HSCs induced extensive hematopoietic cell loss, whereas depletion of Uba1 in B cells, T cells, or megakaryocytes induced corresponding cell death, but these mutant mice appeared normal. Depletion of Uba1 in monocytes and NEs failed to induce cell death, and the mutant mice were viable. Among the tested models, only depletion of Uba1 in NEs induced autoinflammatory symptoms including increased counts and percentages of NEs, increased proinflammatory cytokines, presence of vacuoles in myeloid cells, splenomegaly, and dermatitis. Residual Uba1 was approximately 30% in the mutant NEs, which disrupted cellular hemostasis. Finally, genetic loss of the myeloid prosurvival regulator Morrbid partially mitigated the VEXAS-like symptoms. The established VEXAS-like murine model will further our understanding and treatment of the newly identified autoinflammatory syndrome prevalent among aged men.
Authors
Ge Dong, Jingjing Liu, Wenyan Jin, Hongxi Zhou, Yuchen Wen, Zhiqin Wang, Keyao Xia, Jianlin Zhang, Linxiang Ma, Yunxi Ma, Lorie Chen Cai, Qiufan Zhou, Huaquan Wang, Wei Wei, Ying Fu, Zhigang Cai
Abstract
Sustained CD4+ T cell immunity is required for resolution of acute hepatitis C virus (HCV) infection, but the response remains poorly characterized. Here, circulating CD4+ T cells with high programmed cell death 1 (PD-1) and ICOS coexpression were temporally associated with onset of virus control, seroconversion, and hepatitis in HCV-infected chimpanzees. Coproduction of T follicular helper (Tfh) (IL-21 and CXCL13) and Th1 (IFN-γ and TNF) cytokines after stimulation with HCV nonstructural proteins demonstrated that the response was predominately Tfh1 like and virus specific. Transcriptional analysis verified a Tfh1 lineage assignment. Effector-related genes such as ADGRG1 (GPR56), ZNF683 (Hobit), and KLRB1 (CD161) were also expressed. HCV-specific PD-1hiICOShi CD4+ Tfh1-like cells were enriched in liver, suggesting the potential for B and CD8+ T cell help at the site of virus replication. Most circulating and intrahepatic PD-1hiICOShi CD4+ Tfh1-like cells did not express CXCR5 and therefore resembled CXCR5–CXCL13+ peripheral helper cells that infiltrate tumors and tissues inflamed by autoimmunity. PD-1hiICOShi CD4+ Tfh1-like cells also peaked after hepatitis A virus infection, but the response was accelerated by several weeks compared with HCV infection. The PD-1hiICOShi phenotype and temporal association between the peak response and alanine aminotransferase may provide markers to guide human studies of CD4+ T cell immunity against HCV and other hepatotropic viruses.
Authors
Heather Blasczyk, William Bremer, Christopher C. Phelps, Yan Zhou, David G. Bowen, Zhaohui Xu, Robert Lanford, Naglaa H. Shoukry, Arash Grakoui, Nicole Skinner, Christopher M. Walker
Abstract
Toll like receptor (TLR) 7 and 9, endosomal sensors for RNA and DNA, are key mediators of autoreactivity. Although generally considered homologous, they paradoxically have opposing effects on lupus: TLR7 exacerbates the disease while TLR9 protects from it How they mediate opposing effects in autoimmunity remains undetermined. We hypothesized that differences in signaling qualities of the Toll-Interleukin 1 Receptor (TIR) domains of TLR7 and TLR9 could be responsible for their opposing effects. To test this, we introduced the TIR domain of TLR9 into the endogenous Tlr7 locus and the TLR7 TIR domain into the endogenous Tlr9 locus of mice, creating chimeric molecules termed TLR779 and TLR997. Lupus-prone MRL/lpr mice carrying Tlr779 had greatly ameliorated disease, while MRL/lpr mice carrying Tlr997 had markedly exacerbated disease compared with respective TlrWT mice. These experiments establish that TLR7 and TLR9 TIR domains have divergent properties and control disease quality, thus explaining the longstanding “TLR paradox”.
Authors
Claire Leibler, Kayla B. Thomas, Coralie Josensi, Russell C. Levack, Shuchi Smita, Shinu John, Daniel J. Wikenheiser, Sheldon Bastacky, Sebastien Gingras, Kevin M. Nickerson, Mark J. Shlomchik
Abstract
Severe systemic inflammatory reactions, including sepsis, often lead to shock, organ failure, and death, in part through an acute release of cytokines that promote vascular dysfunction. However, little is known about the vascular endothelial signaling pathways regulating the transcriptional profile in failing organs. Our work focused on signaling downstream of IL-6, due to its clinical importance as a biomarker for disease severity and predictor of mortality. Here, we show that loss of endothelial expression of the IL-6 pathway inhibitor SOCS3 promoted a type I IFN–like (IFNI-like) gene signature in response to endotoxemia in mouse kidneys and brains. In cultured primary human endothelial cells, IL-6 induced transient IFNI-like gene expression in a noncanonical, IFN-independent fashion. We further show that STAT3, which we had previously demonstrated to control IL-6–driven endothelial barrier function, was dispensable for this activity. Instead, IL-6 promoted a transient increase in cytosolic mitochondrial DNA and required STAT1, cGAS, STING, and IRF1, -3, and -4. Inhibition of this pathway in endothelial cell–specific STING-KO mice or global STAT1-KO mice led to reduced the severity of the response to acute endotoxemic challenge and prevented expression of an endotoxin-induced IFNI-like gene signature. These results suggest that permeability and DNA-sensing responses are driven by parallel pathways downstream of this cytokine, provide potential insights into the complex response to acute inflammatory responses, and offer the possibility of novel therapeutic strategies for independently controlling the intracellular responses to IL-6 in order to tailor the inflammatory response.
Authors
Nina Martino, Erin K. Sanders, Ramon Bossardi Ramos, Iria Di John Portela, Fatma Awadalla, Shuhan Lu, Dareen Chuy, Neil Poddar, Mei Xing G. Zuo, Uma Balasubramanian, Peter A. Vincent, Pilar Alcaide, Alejandro P. Adam
Abstract
Idiopathic pulmonary fibrosis (IPF) is a disease of progressive lung remodeling and collagen deposition that leads to respiratory failure. Myeloid cells are abundant in IPF lung and in murine lung fibrosis, but their functional effects are incompletely understood. Using mouse and human lung models, we show that ornithine produced by myeloid cells expressing arginase 1 (ARG1) serves as a substrate for proline and collagen synthesis by lung fibroblasts. The predominant ARG1-expressing myeloid cells in mouse lung were macrophages, but in IPF lung, high-dimensional imaging revealed ARG1 was expressed mainly in neutrophils. Small-molecule ARG1 inhibition suppressed both ornithine levels and collagen expression in cultured, precision-cut IPF lung slices and in murine lung fibrosis. These results were confirmed in macrophage-specific Arg1-KO mice. Furthermore, we found that this pathway is regulated by cell-to-cell crosstalk, starting with purinergic signaling: extracellular ATP receptor P2RX4 was necessary for fibroblast IL-6 expression, which, in turn, was necessary for ARG1 expression by myeloid cells. Taken together, our findings define an immune-mesenchymal circuit that governs profibrotic metabolism in lung fibrosis.
Authors
Preeti Yadav, Javier Gómez Ortega, Prerna Dabral, Whitney Tamaki, Charles Chien, Kai-Chun Chang, Nivedita Biswas, Sixuan Pan, Julia Nilsson, Xiaoyang Yin, Aritra Bhattacharyya, Kaveh Boostanpour, Tanay Jujaray, Jasper T. Wang, Tatsuya Tsukui, Christopher J. Molina, Vincent C. Auyeung, Dean Sheppard, Baosheng Li, Mazharul Maishan, Hiroki Taenaka, Michael A. Matthay, Rieko Muramatsu, Lenka Maliskova, Arnab Ghosh, Walter L. Eckalbar, Ari B. Molofsky, Stanley J. Tamaki, Trever G. Bivona, Adam R. Abate, Allon Wagner, Satish K. Pillai, Paul J. Wolters, Kevin M. Tharp, Mallar Bhattacharya
Abstract
The incretin receptor agonists semaglutide and tirzepatide have transformed the medical management of obesity. The neural mechanisms by which incretin analogs regulate appetite remain incompletely understood, and dissecting this process is critical for the development of next-generation antiobesity drugs that are more targeted and tolerable. Moreover, the physiologic functions of incretins in appetite regulation and gut-brain communication have remained elusive. Using in vivo fiber photometry, we discovered distinct pharmacologic and physiologic roles for the incretin hormones glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1). We showed that GIP, but not GLP-1, was required for normal nutrient-mediated inhibition of hunger-promoting AgRP neurons. By contrast, both GIP and GLP-1 analogs at pharmacologic doses were sufficient to inhibit AgRP neurons. The magnitude of neural inhibition was proportional to the effect of each incretin on food intake, and dual GIP and GLP-1 receptor agonism more potently inhibited AgRP neurons and suppressed food intake than either agonist alone. Our results have revealed a role for endogenous GIP in gut-brain appetite regulation and indicate that incretin analogs act in part via AgRP neurons to mediate their anorectic effects.
Authors
Hayley E. McMorrow, Andrew B. Cohen, Carolyn M. Lorch, Nikolas W. Hayes, Stefan W. Fleps, Joshua A. Frydman, Jessica L. Xia, Ricardo J. Samms, Lisa R. Beutler
Abstract
Mutations that initiate acute myeloid leukemia (AML) can cause clonal expansion without transformation (clonal hematopoiesis). Cooperating mutations, usually in signaling genes, are needed to cause overt disease, but these may require a specific fitness state to be tolerated. Here, we show that nearly all AMLs arising in a mouse model expressing 2 common AML-initiating mutations (Dnmt3aR878H and Npm1cA) acquired a single copy amplification of chromosome 7 (chr7), followed by activating mutations in signaling genes. We show that overexpression of a single gene on chr7 (Gab2, which coordinates signaling pathways) was tolerated in the presence of the Npm1cA mutation, could accelerate the development of AML, and was important for the survival of fully transformed AML cells. GAB2 is likewise overexpressed in many human AMLs with mutations in NPM1 and/or signaling genes, and also in acute promyelocytic leukemia initiated by PML::RARA; the PML::RARA fusion protein may activate GAB2 by directly binding to its 5′ flanking region. A similar pattern of GAB2 overexpression preceding mutations in signaling genes has been described in other human malignancies. GAB2 overexpression may represent an oncogene-driven adaptation that facilitates the action of signaling mutations, suggesting an important (and potentially targetable) missing link between the initiating and progression mutations associated with AML.
Authors
Michael H. Kramer, Stephanie N. Richardson, Yang Li, Tiankai Yin, Nichole M. Helton, Daniel R. George, Michelle Cai, Sai Mukund Ramakrishnan, Casey D.S. Katerndahl, Christopher A. Miller, Timothy J. Ley
Abstract
Osteoarthritis (OA) is the most common joint disease. Controlling the complex pathogenesis is challenging, thus, disease-modifying OA drugs are not available. Forkhead box O (FOXO) transcription factors contribute to cartilage homeostasis through autophagy and oxidative stress resistance. Here, we sought to discover FOXO activators and found that cyproheptadine, a histamine H1 receptor (HRH1) inverse agonist, promoted FOXO3 nuclear translocation and increased FOXO target genes while suppressing inflammation. In a murine OA model, cyproheptadine reduced structural joint tissue damage and pain behaviors. Mechanistically, the inhibition of HRH1 constitutive activity mediated the effects of cyproheptadine on calcium balance between endoplasmic reticulum (ER) and cytoplasm, and FOXO activation was part of this mechanism. The antiinflammatory effect of cyproheptadine involved the inhibition of protein kinase C/NF-κB pathway. HRH1 inhibition also suppressed osteogenesis in mesenchymal stem cells and nerve growth factor expression, which are mechanisms of osteophyte formation and pain behaviors. Moreover, cyproheptadine suppressed ER stress–induced lipogenesis by upregulating insulin-induced gene 1. Our findings suggest that HRH1 constitutive activity controls important OA-promoting mechanisms and indicate that HRH1 inverse agonists are promising drug repurposing candidates for structure and pain improvement in OA.
Authors
Ichiro Kurakazu, Merissa Olmer, Hannah Swahn, Kevin Myers, Chelsea Kenvisay, Yukio Akasaki, Yasuharu Nakashima, Martin K. Lotz
Abstract
Sepsis is a life-threatening disease caused by a dysfunctional host response to infection. During sepsis, inflammation-related immunosuppression is the critical factor causing secondary infection and multiple organ dysfunction syndrome. The regulatory mechanisms underlying Treg differentiation and function, which significantly contribute to septic immunosuppression, require further clarification. In this study, we found that neutrophil extracellular traps (NETs) participated in the development of sepsis-induced immunosuppression by enhancing Treg differentiation and function via direct interaction with CD4+ T cells. Briefly, NETs anchored enolase 1 (ENO1) on the membrane of CD4+ T cells through its key protein myeloperoxidase (MPO) and subsequently recruited interferon-induced transmembrane protein 2 (IFITM2). IFITM2 acted as a DNA receptor that sensed NET-DNA and activated intracellular RAS-associated protein 1B (RAP1B) and its downstream ERK signaling pathway to promote Treg differentiation and function. ENO1 inhibition significantly attenuated NET-induced Treg differentiation and alleviated sepsis in mice. Overall, we demonstrated the role of NETs in sepsis-induced immunosuppression by enhancing Treg differentiation, identified ENO1 as an anchor of NET-MPO, and elucidated the downstream molecular mechanism by which IFITM2-RAP1B-ERK regulates Treg differentiation. These findings improve our understanding of the immunopathogenesis of sepsis and provide potential therapeutic targets for sepsis-induced immunosuppression.
Authors
Yi Jiang, Shenjia Gao, Xiya Li, Hao Sun, Xinyi Wu, Jiahui Gu, Zhaoyuan Chen, Han Wu, Xiaoqiang Zhao, Tongtong Zhang, Ronen Ben-Ami, Yuan Le, Timothy R. Billiar, Changhong Miao, Jie Zhang, Jun Wang, Wankun Chen
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ISSN: 0021-9738 (print), 1558-8238 (online)