Issue published September 2, 2025 Previous issue
- Volume 135, Issue 17
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On the cover: Combating intracellular mycobacterial infections
Andrade et al. identify an antimicrobial gene signature regulated by Th1/Th17 cytokines and associated with reduced Mycobacterium leprae burden, highlighting potential antimicrobial effectors and therapeutic targets for improving mycobacterial infection outcomes. The cover image is a scanning electron micrograph of M. leprae bacilli exposed to CCL17. Image credit: Priscila R. Andrade. Colorized by Robert L. Modlin using ChatGPT Pro.
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Review Series
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Abstract
Inflammatory bowel diseases (IBDs) are complex immune disorders that arise at the intersection of genetic susceptibility, environmental exposures, and dysbiosis of the gut microbiota. Our understanding of the role of the microbiome in IBD has greatly expanded over the past few decades, although efforts to translate this knowledge into precision microbiome-based interventions for the prevention and management of disease have thus far met limited success. Here we survey and synthesize recent primary research in order to propose an updated conceptual framework for the role of the microbiome in IBD. We argue that accounting for gut microbiome context — elements such disease regionality, phase of disease, diet, medication use, and patient lifestyle — is essential for the development of a clear and mechanistic understanding of the microbiome’s contribution to pathogenesis or health. Armed with better mechanistic and contextual understanding, we will be better prepared to translate this knowledge into effective and precise strategies for microbiome restitution.
Authors
Megan S. Kennedy, Eugene B. Chang
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Reviews
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Abstract
Trained immunity (TRIM) is a form of long-lasting functional reprogramming of innate immune cells and their progenitors that enhances responsiveness to subsequent stimuli. Although first characterized in myeloid cells, TRIM was recently extended to nonmyeloid cell types, including endothelial and glial cells, which also exhibit stimulus-driven, memory-like behavior. While initially recognized as a protective mechanism, particularly in the context of vaccines and acute infections, TRIM can also become maladaptive, promoting chronic inflammation, immune dysfunction, and disease. This Review focuses on virus-induced TRIM while also addressing microbial, metabolic, and endogenous inducers. We examine key ligands and receptors that initiate TRIM and dissect the associated signaling and epigenetic pathways. Importantly, we argue that maladaptive TRIM arises not from a specific ligand, receptor, or molecular event, but from contextual factors such as stimulus persistence, dose, tissue microenvironment, and preexisting inflammation. The nature of the secondary challenge also shapes whether a trained response is adaptive or maladaptive. We further discuss TRIM induction in the bone marrow, involvement of both myeloid and nonmyeloid cells, and the role of lipid rafts in sustaining TRIM. We review maladaptive TRIM’s potential contribution to systemic diseases, such as atherosclerosis, diabetes, sepsis, cancer, and autoimmunity, along with its influence on viral vaccine responses. Finally, we outline potential strategies to redirect maladaptive TRIM and propose key outstanding questions for future research.
Authors
Dmitri Sviridov, Mihai G. Netea, Michael I. Bukrinsky
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Air pollution comprises a complex mixture of gaseous and particulate components. Particulate matter (PM) air pollution is associated with 4.7 million premature deaths per year. Among modifiable risk factors, air pollution exposure contributes to 8% of disability adjusted life years and ranks above factors such as high blood pressure, smoking, and high fasting plasma glucose. As the site of entry, exposure to PM air pollution causes respiratory symptoms and is a significant cause of respiratory morbidity and mortality. In this Review, we discuss the studies that link air pollution exposure with respiratory diseases. We review the epidemiological evidence linking PM exposure and lung diseases including asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, pneumonia, acute respiratory distress syndrome, and lung cancer. We also provide an overview of current knowledge about the mechanisms by which PM exerts its biological effects leading to adverse health effects in the respiratory system.
Authors
Robert B. Hamanaka, Gökhan M. Mutlu
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Commentaries
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Abstract
The search for transformative medicines has continuously uncovered select diseases associated with the disruption of the endocannabinoid (eCB) signaling system in the brain and emphasized the therapeutic value of small molecules that rescue this signaling system. In this issue of JCI, Wang et al. report that genetic disruption of PPP2R1A function in mouse forebrain, a preclinical mouse model of neurodevelopmental disorders, resulted in pronounced impairment of eCB signaling. Notably, small-molecule inhibitors of eCB inactivation rescued both eCB signaling and cognitive dysfunction in this model, providing a solid foundation to move such transformative therapeutic approaches based on targeting eCB signaling toward human clinical trial testing.
Authors
Nephi Stella
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Cerebrospinal fluid dynamics play an important role in maintaining brain health and clearing metabolic waste from the brain. In this issue of the JCI, Gursky et al. investigate how CSF distribution is affected when its primary efflux pathway — the deep cervical lymph nodes — is disrupted by cauterization. This timely study reveals compensatory fluid drainage routes from the skull, age-dependent adaptations in CSF homeostasis, and the emergence of neuroinflammation when an efflux pathway is occluded. The findings underscore the need to better understand the physiological mechanisms governing CSF clearance, how these pathways evolve with aging, and whether CSF influx and efflux exhibit region-specific dynamics shaped by neuroanatomy. Additionally, the study raises important questions about whether peripheral injury can influence central nervous system states. A more complete understanding of CSF flow regulation may offer new perspectives on the origins of neuropathology.
Authors
Lauren M. Hablitz, Maiken Nedergaard
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Research Letters
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Abstract
Authors
James G. Krueger, Mrinal K. Sarkar, Mark G. Lebwohl, Akimichi Morita, Kenneth Gordon, Rachael Bogle, Christopher Cole, Anthony Coon, Richard G. Langley, Richard B. Warren, Arash Mostaghimi, Bruce Strober, A. David Burden, Min Zheng, Aaron R. Mangold, Milan J. Anadkat, Jonathan N. Barker, Joseph F. Merola, Lam C. Tsoi, Ming Tang, Kolja Becker, Denis Delic, Christian Thoma, Johann E. Gudjonsson
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Authors
Siyan Cao, Khai M. Nguyen, Kaiming Ma, Tingyi Tan, Xin Yao, Ta-Chiang Liu, Malek Ayoub, Jalpa Devi, Sami Samaan, Yizhou Liu, Radhika Smith, Matthew L. Silviera, Steven R. Hunt, Paul E. Wise, Matthew G. Mutch, Sean C. Glasgow, William C. Chapman Jr., Michelle L. Cowan, Matthew A. Ciorba, Marco Colonna, Parakkal Deepak, SPARC IBD Investigators
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Authors
Rudy J. Castellani, Hinda Najem, Amy B. Heimberger, Pouya Jamshidi
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Research Articles
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Abstract
Metabolic dysfunction–associated steatohepatitis (MASH) is a globally prevalent but intractable disease lacking effective pharmacotherapies. Here, we performed an integrated multilayered screening for pathogenic genes and druggable targets for MASH. We identified the subclass of metabolite-sensing G protein–coupled receptors, specifically GPR31, a critical contributor to MASH occurrence, which, to our knowledge, was previously uncharacterized. Mechanistically, Gαi3 is the essential downstream effector for the pro-MASH efficiency of GPR31 via glycosylation-dependent interaction with GPR31 and extra activation of PKCδ-MAPK signaling. Hepatocyte-specific GPR31 deficiency robustly blocked hepatic lipotoxicity and fibrosis in a mouse model of diet-induced MASH, whereas expression of the GPR31 transgene aggravated MASH development. Of translational importance, we developed a small-molecule inhibitor, named G4451, that specifically inhibits the GPR31-Gαi3 interaction by targeting the GPR31 conformational transition. Encouragingly, oral administration of G4451 effectively blocked MASH progression in preclinical models in both rodents and nonhuman primates. Collectively, the present study provides proof of concept that interference with GPR31 constitutes an attractive therapeutic strategy for MASH.
Authors
Xiao-Jing Zhang, Jiajun Fu, Xu Cheng, Hong Shen, Hailong Yang, Kun Wang, Wei Li, Han Tian, Tian Tian, Junjie Zhou, Song Tian, Zhouxiang Wang, Juan Wan, Lan Bai, Hongfei Duan, Xin Zhang, Ruifeng Tian, Haibo Xu, Rufang Liao, Toujun Zou, Jing Shi, Weiyi Qu, Liang Fang, Jingjing Cai, Peng Zhang, Zhi-Gang She, Jingwei Jiang, Yufeng Hu, Yibin Wang, Hongliang Li
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Congenital hydrocephalus is a life-threatening condition that might affect brain development by increasing the pressure on the brain parenchyma. Here, we describe 6 male patients from 1 family, all presenting with an isolated X-linked congenital hydrocephalus. Exome sequencing identified a likely pathogenic variant of angiomotin (AMOT) that segregated with the phenotype in the extended family. We show that the variant, affecting the first methionine, translated into a shorter AMOT protein lacking 91 amino acids from the N-terminus. Mechanistically, we unraveled that the absence of the N-terminus leads to abnormally increased AMOT protein levels due to the loss of both the N-degron degradation signal and the tankyrase-binding domain. Altered degradation of AMOT disrupted the barrier integrity of the cells. Thus, the identified AMOT variant likely underlies the clinical presentation of isolated X-linked hydrocephalus in this family, and our data underscore the importance of tight regulation of AMOT protein level in the brain. AMOT now joins the list of genes involved in congenital hydrocephalus in humans. These findings are instrumental for the genetic counseling of affected families.
Authors
Nurcan Hastar, Hagit Daum, Nikoletta Kardos-Török, Gael Ganz, Leon Obendorf, Peter Vajkoczy, Orly Elpeleg, Petra Knaus
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Coatomer protein complex subunit α (COPA) syndrome is a monogenic disorder of immune dysregulation that leads to interstitial lung disease and high-titer autoantibodies. Constitutive activation of the innate immune molecule stimulator of interferon genes (STING) is centrally involved in disease. However, the mechanisms by which STING results in autoimmunity are not well understood in COPA syndrome and other STING-associated diseases. Prior studies showed a cell autonomous role for STING in thymocyte development. Single-cell data of human thymus demonstrated that STING is highly expressed in medullary thymic epithelial cells (mTECs) and at levels much greater than in T cells. Here, we show that in certain contexts, activated STING exerts a functional role in the thymic epithelium to alter thymocyte selection and predisposes to autoimmunity. In CopaE241K/+ mice, activated STING in mTECs amplified IFN signaling, impaired macroautophagy, and caused a defect in negative selection of T cell precursors. WT mice given a systemic STING agonist phenocopied the selection defect and showed enhanced thymic escape of a T cell clone targeting a self-antigen also expressed in melanoma. Our work demonstrates that STING activation in TECs shapes the T cell repertoire and contributes to autoimmunity, findings that are important for conditions that activate thymic STING.
Authors
Zimu Deng, Christopher S. Law, Santosh Kurra, Noa Simchoni, Anthony K. Shum
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The balance of hematopoietic stem cell (HSC) self-renewal versus differentiation is essential to ensure long-term repopulation capacity while allowing response to events that require increased hematopoietic output. Proliferation and differentiation of HSCs and their progeny are controlled by the JAK/STAT pathway downstream of cytokine signaling. E3 ubiquitin ligases, like Cullin 5 (CUL5), can regulate JAK/STAT signaling by degrading signaling intermediates. Here we report that mice lacking CUL5 in hematopoietic cells (Cul5Vav-Cre) have increased numbers of hematopoietic stem and progenitor cells (HSPCs), splenomegaly, and extramedullary hematopoiesis. Differentiation in Cul5Vav-Cre mice is myeloid- and megakaryocyte-biased, resulting in leukocytosis, anemia, and thrombocytosis. Cul5Vav-Cre mice had increased HSC proliferation and circulation, associated with a decrease in CXCR4 surface expression. In bone marrow cells, we identified LRRC41 coimmunoprecipitated with CUL5, and vice versa, supporting that CRL5 forms a complex with LRRC41. We identified an accumulation of LRRC41 and STAT5 in Cul5Vav-Cre HSCs during IL-3 stimulation, supporting their regulation by CUL5. Whole-cell proteome analysis of HSPCs from Cul5Vav-Cre bone marrow identified upregulation of many STAT5 target genes and associated pathways. Finally, JAK1/2 inhibition with ruxolitinib normalized hematopoiesis in Cul5Vav-Cre mice. These studies demonstrate the function of CUL5 in HSC function, stem cell fate decisions, and regulation of IL-3 signaling.
Authors
Siera A. Tomishima, Dale D. Kim, Nadia Porter, Ipsita Guha, Asif A. Dar, Yohaniz Ortega-Burgos, Jennifer Roof, Hossein Fazelinia, Lynn A. Spruce, Christopher S. Thom, Robert L. Bowman, Paula M. Oliver
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Facioscapulohumeral muscular dystrophy (FSHD) is a genetic muscle disease caused by ectopic expression of the toxic protein DUX4, resulting in muscle weakness. However, the mechanism by which DUX4 exerts its toxicity remains unclear. In this study, we observed abnormal iron accumulation in muscles of patients with FSHD and in mice with muscle-specific DUX4 expression (DUX4-Tg mice). Treatment with iron chelators, an iron-deficient diet, and genetic modifications inhibiting intracellular uptake of iron did not improve but rather exacerbated FSHD pathology in DUX4-Tg mice. Unexpectedly, however, iron supplementation, from either a high-iron diet or intravenous iron administration, resulted in remarkable improvement in grip strength and running performance in DUX4-Tg mice. Iron supplementation suppressed abnormal iron accumulation and the ferroptosis-related pathway involving increased lipid peroxidation in DUX4-Tg muscle. Muscle-specific DUX4 expression led to retinal vasculopathy, a part of FSHD pathology, which was prevented by iron administration. Furthermore, high-throughput compound screening of the ferroptosis pathway identified drug candidates including ferrostatin-1 (Fer-1), a potent inhibitor of lipid peroxidation. Treatment with Fer-1 dramatically improved physical function in DUX4-Tg mice. Our findings demonstrate that DUX4-provoked toxicity is involved in the activation of the ferroptosis-related pathway and that supplementary iron could be a promising and readily available therapeutic option for FSHD.
Authors
Kodai Nakamura, Huascar Pedro Ortuste Quiroga, Naoki Horii, Shin Fujimaki, Toshiro Moroishi, Keiichi I. Nakayama, Shinjiro Hino, Yoshihiko Saito, Ichizo Nishino, Yusuke Ono
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The outflow of ‘dirty’ brain fluids from the glymphatic system drains via the meningeal lymphatic vessels to the lymph nodes in the neck, primarily the deep cervical lymph nodes (dcLN). However, it is unclear whether dcLN drainage is essential for normal cerebral homeostasis. Using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and computational fluid dynamics, we studied the impact of long-term mechanical stress from compromised dcLN drainage on brain solute and fluid outflow in anesthetized rats. We found that in young, but not middle-aged, rats, impairment of dcLN drainage was linked to moderately increased intracranial pressure and the emergence of extracranial perivenous drainage, with no evidence of hydrocephalus at any age. Surprisingly, both age groups showed enhanced brain solute clearance despite reduced glymphatic influx. CSF proteomic analysis revealed cellular stress in the form of low-grade inflammation and upregulation of pathways associated with neurodegeneration and blood brain barrier leakage in the rats with impaired lymphatic drainage. Our findings highlight that dcLN drainage is indeed a prerequisite for normal cerebral homeostasis in the rat and reveal the brain’s age-dependent compensatory responses to chronic impairment of its lymphatic drainage pathways.
Authors
Zachary Gursky, Zohaib Nisar Khan, Sunil Koundal, Ankita Bhardwaj, Joaquin Caceres Melgarejo, Kaiming Xu, Xinan Chen, Hung-Mo Lin, Xianfeng Gu, Hedok Lee, Jonathan Kipnis, Yoav Dori, Allen Tannenbaum, Laura Santambrogio, Helene Benveniste
×Abstract
There is growing evidence for direct actions of follicle-stimulating hormone (FSH) on tissues other than the ovaries and testes. Blocking FSH action, either genetically or pharmacologically, protects against bone loss, fat gain, and memory loss in mice. We thus developed a humanized FSH-blocking antibody, MS-Hu6, as a lead therapeutic for 3 diseases of public health magnitude — osteoporosis, obesity, and Alzheimer’s disease (AD) — that track together in postmenopausal women. Here, we report the crystal structure of MS-Hu6 and its interaction with FSH in atomistic detail. Using our Good Laboratory Practice platform (21 CFR 58), we formulated MS-Hu6 and the murine equivalent, Hf2, at an ultra-high concentration; both formulated antibodies displayed enhanced thermal and colloidal stability. A single injection of 89Zr-labeled MS-Hu6 revealed a β phase t½ of 79 and 132 hours for female and male mice, respectively, with retention in regions of interest. Female mice injected subcutaneously with Hf2 displayed a dose-dependent reduction in body weight and body fat, in the face of reduced free (bioavailable) FSH and unperturbed estrogen levels. Hf2 also rescued recognition memory and spatial learning loss in a context- and time-dependent manner in AD-prone 3xTg and APP/PS1 mice. MS-Hu6 injected into African green monkeys (8 mg/kg) intravenously, and then subcutaneously at monthly intervals, was safe, and without effects on vital signs, blood chemistries, or blood counts. There was a notable approximately 4% weight loss in all 4 monkeys after the first injection, which continued in 2 of the monkeys. We thus provide Investigational New Drug–enabling data for a planned first-in-human study.
Authors
Anusha R. Pallapati, Funda Korkmaz, Satish Rojekar, Steven Sims, Anurag Misra, Judit Gimenez-Roig, Aishwarya Gangadhar, Victoria Laurencin, Anisa Gumerova, Uliana Cheliadinova, Farhath Sultana, Darya Vasilyeva, Liam Cullen, Jonathan Schuermann, Jazz Munitz, Hasni Kannangara, Surabhi Parte, Georgii Pevnev, Guzel Burganova, Zehra Tumoglu, Ronit Witztum, Soleil Wizman, Natan Kramskiy, Liah Igel, Fazilet Sen, Anna Ranzenigo, Anne Macdonald, Susan Hutchison, Abraham J.P. Teunissen, Heather Burkart, Mansi Saxena, Yelena Ginsburg, Ki Goosens, Weibin Zhou, Vitaly Ryu, Ofer Moldavski, Orly Barak, Michael Pazianas, John Caminis, Shalender Bhasin, Richard Fitzgerald, Se-Min Kim, Matthew Quinn, Shozeb Haider, Susan Appt, Tal Frolinger, Clifford J. Rosen, Daria Lizneva, Yogesh K. Gupta, Tony Yuen, Mone Zaidi
×Abstract
Protein phosphatase 2A (PP2A) is a serine/threonine phosphatase in the brain. Mutations in PPP2R1A, encoding the scaffolding subunit, are linked to intellectual disability, although the underlying mechanisms remain unclear. This study examined mice with heterozygous deletion of Ppp2r1a in forebrain excitatory neurons (NEX-het-conditional knockout [NEX-het-cKO]). These mice exhibited impaired spatial learning and memory, resembling Ppp2r1a-associated intellectual disability. Ppp2r1a haploinsufficiency also led to increased excitatory synaptic strength and reduced inhibitory synapse numbers on pyramidal neurons. The increased excitatory synaptic transmission was attributed to increased presynaptic release probability, likely due to reduced levels of 2-arachidonoyl glycerol (2-AG). This reduction in 2-AG was associated with increased transcription of monoacylglycerol lipase (MAGL), driven by destabilization of enhancer of zeste homolog 2 (EZH2) in NEX-het-cKO mice. Importantly, the MAGL inhibitor JZL184 effectively restored both synaptic and learning deficits. Our findings uncover an unexpected role of PPP2R1A in regulating endocannabinoid signaling, providing fresh molecular and synaptic insights into the mechanisms underlying intellectual disability.
Authors
Yirong Wang, Weicheng Duan, Hua Li, Zhiwei Tang, Ruyi Cai, Shangxuan Cai, Guanghao Deng, Liangpei Chen, Hongyan Luo, Liping Chen, Yulong Li, Jian-Zhi Wang, Bo Xiong, Man Jiang
×Abstract
A20, encoded by the TNFAIP3 gene, is a protein linked to Crohn’s disease and celiac disease in humans. We now find that mice expressing point mutations in A20’s M1-ubiquitin–binding zinc finger 7 (ZF7) motif spontaneously develop proximal enteritis that requires both luminal microbes and T cells. Cellular and transcriptomic profiling reveals expansion of Th17 cells and exuberant expression of IL-17A and IL-22 in intestinal lamina propria of A20ZF7 mice. While deletion of IL-17A from A20ZF7/ZF7 mice exacerbates enteritis, deletion of IL-22 abrogates intestinal epithelial cell hyperproliferation, barrier dysfunction, and alarmin expression. Colonization of adult germ-free mice with microbiota from adult WT specific pathogen–free mice drives duodenal IL-22 expression and duodenitis. A20ZF7/ZF7 Th17 cells autonomously express more RORγt and IL-22 after differentiation in vitro. ATAC sequencing identified an enhancer region upstream of the Il22 gene, and this enhancer demonstrated increased activating histone acetylation coupled with exaggerated Il22 transcription in A20ZF7/ZF7 T cells. Acute inhibition of RORγt normalized histone acetylation at this enhancer. Finally, CRISPR/Cas9–mediated ablation of A20ZF7 in human T cells increases RORγt expression and IL22 transcription. These studies link A20’s M1-ubiquitin binding function with RORγt expression, expansion of Th17 cells, and epigenetic activation of IL-22–driven enteritis.
Authors
Christopher J. Bowman, Dorothea M. Stibor, Xiaofei Sun, Nika Lenci, Hiromichi Shimizu, Emily F. Yamashita, Rommel Advincula, Min Cheol Kim, Jessie A. Turnbaugh, Yang Sun, Bahram Razani, Peter J. Turnbaugh, Chun Jimmie Ye, Barbara A. Malynn, Averil Ma
×Abstract
The dystrophin-glycoprotein complex (DGC) is composed of peripheral and integral membrane proteins at the muscle cell membrane that link the extracellular matrix with the intracellular cytoskeleton. While it is well established that genetic mutations that disrupt the structural integrity of the DGC result in numerous muscular dystrophies, the 3D structure of the complex has remained elusive. Two recent elegant cryoEM structures of the DGC illuminate its molecular architecture and reveal the unique structural placement of sarcospan (SSPN) within the complex. SSPN, a 25 kDa tetraspanin-like protein, anchors β-dystroglycan to the β-, γ- and δ-sarcoglycan trimer, supporting the conclusions of biochemical studies that SSPN is a core element for DGC assembly and stabilization. Here, we advance these studies by revealing that SSPN provides scaffolding in δ-sarcoglycanopathies, enabling substitution of δ-sarcoglycan by its homolog, ζ-sarcoglycan, leading to the structural integrity of the DGC and prevention of limb-girdle muscular dystrophy R5. Three-dimensional modeling reveals that ζ-sarcoglycan preserves protein-protein interactions with the sarcospan, sarcoglycans, dystroglycan, and dystrophin. The structural integrity of the complex maintains myofiber attachment to the extracellular matrix and protects the cell membrane from contraction-induced damage. These findings demonstrate that sarcospan prevents limb-girdle muscular dystrophy R5 by remodeling of the sarcoglycan complex composition.
Authors
Ekaterina I. Mokhonova, Daniel Helzer, Ravinder Malik, Hafsa Mamsa, Jackson Walker, Mark Maslanka, Tess S. Fleser, Mohammad H. Afsharinia, Shiheng Liu, Johan Holmberg, Z. Hong Zhou, Eric J. Deeds, Kirk C. Hansen, Elizabeth M. McNally, Rachelle H. Crosbie
×Abstract
Cytoplasmic transactive response DNA-binding protein 43 (TDP43) mislocalization and aggregation are pathological hallmarks of amyotrophic lateral sclerosis (ALS). However, the initial cellular insults that lead to TDP43 mislocalization remain unclear. In this study, we demonstrate that nemo-like kinase (NLK) — a proline-directed serine-threonine kinase — promotes the mislocalization of TDP43 and other RNA-binding proteins by disrupting nuclear import. NLK levels were selectively elevated in neurons exhibiting TDP43 mislocalization in tissues from patients with ALS, and genetic reduction of NLK reduced toxicity in human neuron models of ALS. Our findings suggest that NLK is a promising therapeutic target for neurodegenerative diseases.
Authors
Michael E. Bekier II, Emile Pinarbasi, Gopinath Krishnan, Jack J. Mesojedec, Madelaine Hurley, Harisankar Harikumar Sheela, Catherine A. Collins, Layla Ghaffari, Martina de Majo, Erik M. Ullian, Mark Koontz, Sarah Coleman, Xingli Li, Elizabeth M.H. Tank, Jacob Waksmacki, Fen-Biao Gao, Sami J. Barmada
×Abstract
Bloodstream bacterial infections cause one-third of deaths from bacterial infections, and eradication of circulating bacteria is essential to prevent disseminated infections. Here, we found that hepcidin, the master regulator of systemic iron homeostasis, affected Kupffer cell (KC) immune defense against bloodstream bacterial infections by modulating the gut commensal bacteria–derived tryptophan derivative indole-3-propionic acid (IPA). Hepcidin deficiency impaired bacterial capture by KCs and exacerbated systemic bacterial dissemination through morphological changes in KCs. Gut microbiota depletion and fecal microbiota transplantation revealed that the gut microbiota mediated the alteration of KCs volume. Mechanistically, hepcidin deficiency led to a decreased abundance of the IPA-producing commensal Lactobacillus intestinalis and a concomitant reduction in the gut-to-liver shuttling of its metabolite IPA. IPA supplementation or L. intestinalis colonization restored the KC volume and hepatic immune defense against bloodstream bacterial infection in hepcidin-deficient mice. Moreover, hepcidin levels in patients with bacteremia were associated with days of antibiotic usage and hospitalization. Collectively, our findings highlight a previously unappreciated role of hepcidin in sustaining KC-mediated hepatic defense against bloodstream bacterial infections through the gut commensal L. intestinalis and its tryptophan derivative IPA. More importantly, we show that restoring the crosstalk between the gut microbiota and liver through IPA-inspired therapies may offer a promising strategy for enhancing the host defense against bloodstream bacterial infections in those with low hepcidin levels and a high risk for bacterial infections.
Authors
Yihang Pan, Lihua Shen, Zehua Wu, Xueke Wang, Xiwang Liu, Yan Zhang, Qinyu Luo, Sijin Liu, Xiangming Fang, Qiang Shu, Qixing Chen
×Abstract
Elevated cholesterol poses cardiovascular risks. The glucocorticoid receptor (GR) harbors a still undefined role in cholesterol regulation. Here, we report that a coding SNP in the gene encoding the GR, rs6190, is associated with increased cholesterol in women according to UK Biobank and All of Us (NIH) datasets. In SNP-genocopying mice, we found that the SNP enhanced hepatic GR activity to transactivate Pcsk9 and Bhlhe40, negative regulators of LDL and HDL receptors, respectively. In mice, the SNP was sufficient to elevate circulating cholesterol across all lipoprotein fractions and the risk and severity of atherosclerotic lesions on the proatherogenic hAPOE*2/*2 background. The SNP effect on atherosclerosis was blocked by in vivo liver knockdown of Pcsk9 and Bhlhe40. Also, corticosterone and testosterone were protective against the mutant GR program in cholesterol and atherosclerosis in male mice, while the SNP effect was additive to estrogen loss in females. Remarkably, we found that the mutant GR program was conserved in human hepatocyte-like cells using CRISPR-engineered, SNP-genocopying human induced pluripotent stem cells. Taken together, our study leverages a nonrare human variant to uncover a GR-dependent mechanism contributing to atherogenic risk, particularly in women.
Authors
Hima Bindu Durumutla, April Haller, Greta Noble, Ashok Daniel Prabakaran, Kevin McFarland, Hannah Latimer, Akanksha Rajput, Olukunle Akinborewa, Bahram Namjou-Khales, David Y. Hui, Mattia Quattrocelli
×Abstract
Neuropathic pain is often comorbid with affective disorders. Synaptic plasticity in anterior cingulate cortex (ACC) is assumed to be a crucial interface for pain perception and emotion. Laminin 1 (LAMB1), a key element of extracellular matrix (ECM) in ACC was recently revealed to convey extracellular alterations to intracellular synaptic plasticity and underlie neuropathic pain and aversive emotion. However, it remains elusive what triggers activity-dependent changes of LAMB1 and ECM remodeling after nerve injury. Here, we uncovered a key role of retinoic acid (RA)/RA receptor β (RARB) signaling in neuropathic pain and associated anxiodepression via regulation of ECM homeostasis. We showed that nerve injury reduced RA levels in the serum and ACC in mice and humans, which brought about downregulation of RA’s corresponding receptor, RARB. Overexpressing RARB relieved pain hypersensitivity and comorbid anxiodepression, while silencing RARB exacerbated pain sensitivity and induced anxiodepression. Further mechanistic analysis revealed that RARB maintained ECM homeostasis via transcriptional regulation of LAMB1, reversing abnormal synaptic plasticity and eventually improving neuropathic pain and aversive emotion. Taken together with our previous study, we revealed an intracellular-extracellular-intracellular feed-forward regulatory network in modulating pain plasticity. Moreover, we identified cingulate RA/RARB signaling as a promising therapeutic target for treatment of neuropathic pain and associated anxiodepression.
Authors
Zhen-Zhen Li, Wan-Neng Liu, Ke-Xin Liu, Zhi-Wei Dou, Rui Zhao, Yun Chen, Meng-Meng Wang, Tao-Zhi Wang, Fei Wang, Wen-Juan Han, Wen-Guang Chu, Xing-Xing Zheng, Rou-Gang Xie, Hua Yuan, Xiao-Fan Jiang, Xiao-Long Sun, Ceng Luo, Sheng-Xi Wu
×Abstract
BACKGROUND Reversal reactions (RRs) in leprosy are acute immune episodes marked by inflammation and bacterial clearance, offering a model to study the dynamics of host responses to Mycobacterium leprae. These episodes are often severe and difficult to treat, frequently progressing to permanent disabilities. We aimed to characterize the immune mechanisms and identify antimicrobial effectors during RRs.METHODS We performed RNA-Seq on paired skin biopsy specimens collected from 9 patients with leprosy before and at RR diagnosis, followed by differential gene expression and functional analysis. A machine-learning classifier was applied to predict membrane-permeabilizing proteins. Antimicrobial activity was assessed in M. leprae–infected macrophages and axenic cultures.RESULTS In the paired pre-RR and RR biopsy specimens, a 64-gene antimicrobial response signature was upregulated during RR and correlated with reduced M. leprae burden. Predicted upstream regulators included IL-1β, TNF, IFN-γ, and IL-17, indicating activation of both the Th1 and Th17 pathways. A machine-learning classifier identified 28 genes with predicted membrane-permeabilizing antimicrobial activity, including S100A8. Four proteins (S100A7, S100A8, CCL17, and CCL19) demonstrated antimicrobial activity against M. leprae in vitro. Scanning electron microscopy revealed membrane damage in bacteria exposed to these proteins.CONCLUSION RR is associated with a robust antimicrobial gene program regulated by Th1 and Th17 cytokines. We identified potentially novel host antimicrobial effectors that showed activity against M. leprae, suggesting potential strategies to bolster Th1 and Th17 responses for combating intracellular mycobacterial infections.FUNDING NIH grants R01 AI022553, R01 AR040312, R01 AR073252, R01 AI166313, R01 AI169526, P50 AR080594, and 4R37 AI052453-21 and National Science Foundation (NSF) grant DMR2325840.
Authors
Priscila R. Andrade, Feiyang Ma, Jing Lu, Jaime de Anda, Ernest Y. Lee, George W. Agak, Craig J. Dobry, Bruno J. de Andrade Silva, Rosane M.B. Teles, Lilah A. Mansky, Jonathan Perrie, Dennis J. Montoya, Bryan D. Bryson, Johann E. Gudjonsson, Gerard C.L. Wong, Euzenir N. Sarno, Matteo Pellegrini, Robert L. Modlin
×Abstract
Because the lung is a mucosal barrier organ with a unique immunologic environment, mechanisms of immunoregulation in lung cancer may differ from those of other malignancies. Consistent with this notion, we found that CD8+ T cells played a paradoxical role in facilitating, rather than ameliorating, the growth of multiple lung adenocarcinoma models. These included spontaneous, carcinogen-induced, and transplantable tumor cell line models. Specifically, we found that CD8+ T cells promoted homing of CD4+Foxp3+ Tregs to the tumor bed by increasing the levels of CCR5 chemokines in the tumor microenvironment in an IFN-γ– and TNF-α–dependent manner. Contrary to their canonical role, these Th1 cytokines contributed to accelerated growth of murine lung adenocarcinomas, while suppressing the growth of other malignancies. Surprisingly, lung cancer cells themselves can serve as a dominant source of IFN-γ, and deletion of this cytokine from cancer cells using CRISPR/Cas9 decreases tumor growth. Importantly for translational applications, in patients with lung cancer, a high level of IFN-γ was also found at both the mRNA and protein levels. Our data outline what we deem a novel and previously undefined lung cancer–specific immunoregulatory pathway that may be harnessed to tailor immune-based therapy specifically for this malignancy.
Authors
Christina Kratzmeier, Mojtaba Taheri, Zhongcheng Mei, Isabelle Lim, May A. Khalil, Brandon Carter-Cooper, Rachel E. Fanaroff, Chin S. Ong, Eric B. Schneider, Stephanie Chang, Erica Leyder, Dongge Li, Irina G. Luzina, Anirban Banerjee, Alexander Sasha Krupnick
×Abstract
BACKGROUND Patients with sickle cell disease (SCD) frequently receive RBC units stored near the end of their permissible storage duration. We aimed to determine whether RBC storage duration influences recipient hematological, metabolic, and clinical chemistry parameters.METHODS In a randomized, prospective, double-blind trial, 24 adults with SCD receiving chronic transfusion therapy were assigned to receive three consecutive outpatient transfusions with RBCs stored for either ≤10 days (short-stored; n = 13) or ≥30 days (long-stored; n = 11). Blood samples were collected from transfused units and from recipients at predefined time points for metabolomics, cytokine, and clinical laboratory analyses. The primary outcomes included post-transfusion hemoglobin and RBC count increments, metabolic markers of oxidative stress, iron metabolism, inflammation, and renal function.RESULTS Transfusion of short-stored RBCs was associated with significantly higher circulating 2,3-bisphosphoglycerate levels for up to 2 weeks after transfusion. Nadir RBC counts and hemoglobin A levels were higher in recipients of short-stored RBCs. In contrast, recipients of long-stored RBCs had higher transferrin saturation and plasma iron levels, elevated markers of oxidative stress and renal dysfunction, and increased proinflammatory cytokines and immunomodulatory metabolites. Metabolomics revealed storage age–dependent alterations in glycolysis, purine, and sphingolipid metabolism. Cytokine profiles and hematologic parameters corroborated the metabolic findings, indicating improved post-transfusion metabolic and inflammatory status with short-stored RBCs.CONCLUSION Transfusion of short-stored RBCs yielded favorable metabolic and hematologic outcomes in adults with SCD, independent of immediate clinical endpoints.TRIAL REGISTRATION ClinicalTrials.gov NCT03704922FUNDING National Heart, Lung, and Blood Institute (NHLBI), NIH (K23HL136787, R01HL148151, R01HL146442, and R01HL149714).
Authors
Matthew S. Karafin, Abby L. Grier, Ross M. Fasano, Anton Ilich, David Wichlan, Ada Chang, Sonjile M. James, Hailly E. Butler, Oleg Kolupaev, Melissa C. Caughey, Daniel J. Stephenson, Julie A. Reisz, Nigel S. Key, Joshua J. Field, Jane A. Little, Steven L. Spitalnik, Angelo D’Alessandro
×Abstract
Oncogene expression can cause replication stress (RS), leading to DNA double-strand breaks (DSBs) that require repair through pathways such as homologous recombination, nonhomologous end-joining, and microhomology-mediated end-joining (MMEJ). Cyclin D1 (encoded by CCND1) is a well-known oncoprotein overexpressed in cancer; however, its role in RS is unknown. Using mantle cell lymphoma (MCL) as a naturally occurring model of cyclin D1 overexpression, we examined the impact of cyclin D1 on RS and DSB repair mechanisms. Cyclin D1 overexpression elevated RS, increased DNA damage, especially during mitosis, and caused specific upregulation of MMEJ. Furthermore, cyclin D1 activated polymerase theta (POLQ) transcription by binding its promoter loci, driving POLΘ-mediated MMEJ that is essential to withstand cyclin D1–induced RS. Moreover, concurrent ATM deficiency further intensified RS, enhanced POLQ expression, and heightened reliance on MMEJ-mediated DNA damage repair. Consequently, inhibition of POLΘ in cyclin D1–overexpressed settings further exacerbated RS, causing single-strand DNA gap accumulations and chromosomal instability, ultimately leading to apoptosis, an effect amplified in ATM-deficient cells. Targeting MMEJ via POLΘ inhibition is therefore an effective strategy in the context of cyclin D1 overexpression and ATM deficiency and may provide a unique therapeutic approach for treating MCL and other malignancies characterized by similar alterations.
Authors
Jithma P. Abeykoon, Shuhei Asada, Guangli Zhu, Yuna Hirohashi, Lisa Moreau, Divya Iyer, Sirisha Mukkavalli, Kalindi Parmar, Gabriella Zambrano, Lige Jiang, Dongni Yi, Michelle Manske, Kimberly Gwin, Rebecca L. King, James R. Cerhan, Xiaosheng Wu, Zhenkun Lou, Geoffrey I. Shapiro, Thomas Witzig, Alan D’Andrea
×Abstract
SPNS1 is a lysosomal transporter that mediates the salvage of lysoglycerophospholipids, the degradative products of lysosomal phospholipid catabolism. However, an understanding of the role of lysolipid transport and salvage in regulating cellular lipid homeostasis and in disease is lacking. Here, we identified members of 2 families with biallelic SPNS1 loss-of-function variants, who presented primarily with progressive liver and striated muscle injury. Patients’ fibroblasts accumulated lysophospholipids including lysoplasmalogens and cholesterol in lysosomes with reduced cellular plasmalogens. Notably, SPNS1 deficiency resulted in reduced biogenesis of cytosolic lipid droplets containing triglycerides and cholesteryl esters. Mechanistically, we found that lysophospholipids transported by SPNS1 into the cytosol quantitatively contributed to triglyceride synthesis, whereas lysosomal buildup of lyso-ether-phospholipid inhibited lysosomal cholesterol egress, effects that were enhanced with inhibition of mTOR. These findings support a gene-disease association and reveal connectivity between lysosomal transport of lysophospholipids and storage of reserve cellular energy as triglycerides and the regulation of cholesterol homeostasis, processes that become important under nutrient limitation.
Authors
Menglan He, Mei Ding, Michaela Chocholouskova, Cheen Fei Chin, Martin Engvall, Helena Malmgren, Matias Wagner, Marlen C. Lauffer, Jacob Heisinger, May Christine V. Malicdan, Valerie Allamand, Madeleine Durbeej, Angelica Delgado Vega, Thomas Sejersen, Ann Nordgren, Federico Torta, David L. Silver
×Abstract
Although virus-like particle (VLP) vaccines were shown to be effective against several viruses, their advantage over vaccines that include envelope protein only is not completely clear, particularly for mRNA-encoded VLPs. We conducted a side-by-side comparison of the immunogenicity and protective efficacy of mRNA vaccines encoding the Marburg virus (MARV) full-length glycoprotein (GP) delivered alone or as a VLP. Electron microscopy confirmed VLP formation when MARV GP and matrix protein VP40 were coexpressed. We vaccinated guinea pigs with a 2-component mRNA vaccine encoding GP and VP40 (VLP) or GP alone. At the highest dose, both vaccines protected fully, although the VLP vaccine elicited a slightly lower humoral response than did the GP-only mRNA vaccine. However, at low doses, GP-only mRNA conferred 100% protection, whereas the VLP vaccine conferred only partial protection. In mice, VLP mRNA induced a moderate preference for GP-specific CD8+ T cell responses, whereas the GP-only mRNA somewhat favored CD4+ T cell responses. Guinea pig whole-blood RNA-Seq revealed that the VLP vaccine downregulated genes associated with various biological and metabolic processes, including the NF-κB signaling pathway, whereas the GP-only vaccine upregulated IFN signaling. Overall, the VLP mRNA vaccine was less immunogenic and protective, whereas the GP-only mRNA vaccine conferred robust protection with a dose of as little as 1 μg in guinea pigs.
Authors
Chandru Subramani, Michelle Meyer, Matthew A. Hyde, Margaret E. Comeaux, Haiping Hao, James E. Crowe Jr., Vsevolod L. Popov, Harshwardhan Thaker, Sunny Himansu, Andrea Carfi, Alexander Bukreyev
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