Issue published June 16, 2025 Previous issue

On the cover: Colistin activity against multidrug-resistant mcr+ bacterial pathogens

Kumaraswamy et al. report that the antibiotic colistin retains antimicrobial activity against multidrug-resistant bacterial pathogens expressing the plasmid-borne mobilized colistin resistance (mcr) gene in the presence of physiologic media or host immunity, although this activity is not detected using standard antimicrobial susceptibility testing. Image credit: Adapted from Jezper/Shutterstock and Basica/Shutterstock.

Review Series
Abstract

The complement system is an important component of the innate immune system involved in host defense and maintaining homeostasis. While the liver is the main source of complement proteins in the bloodstream, recent research has shown that various tissues, including the kidneys, can produce complement components locally in response to both acute and chronic inflammation. This Review highlights evidence from animal models of glomerular and tubulointerstitial kidney disease showing increased expression of intracellular complement in the kidneys. Studies using knockout mice for complement and complement receptors, along with complement inhibitors, have demonstrated that reduced complement activation in animal models of kidney fibrosis led to reduced inflammation and fibrosis, thereby supporting the pathogenic role of complement activation. Data from single-cell RNA-sequencing, spatial transcriptomics, and proteomics studies further demonstrate that alterations in local complement levels contribute to the fibrotic microenvironment observed in these models. Additionally, kidney biopsy results from patients with acute kidney injury and chronic kidney disease (CKD) indicate an increased expression of intracellular complement components as disease progresses. Developing drugs aimed at diminishing the expression and activation of local complement in glomerular and tubulointerstitial kidney disease could provide a novel approach to managing CKD.

Authors

Didier Portilla, Vikram Sabapathy, Daniel Chauss

×

Abstract

Animal experiments have long been a cornerstone of advancements in biomedical research, particularly in developing novel therapeutic strategies for inflammatory and autoimmune diseases. However, these historically important approaches are now facing growing scrutiny for ethical reasons, concerns about translational limitations to human biology, and the rising availability of animal-free research methods. This shift raises a critical question: How relevant and effective are animal models for driving future advancements in today’s research landscape? This Review aims to explore this question within the field of biomedical research on the complement system, critically evaluating the contribution of animal models to the recent advancements and clinical successes of complement-targeted therapies. Specifically, we assess areas where animal studies have been indispensable for elucidating disease mechanisms and conducting preclinical evaluations, alongside instances where findings from animal models failed to translate successfully to human trials. Furthermore, we discuss similarities and differences in the complement system between animals and humans and explore innovations in animal research designed to improve translatability to human biology. By assessing the contributions of animal studies to complement therapeutics, this Review aims to provide insights into animal models’ strengths, limitations, and evolving role in complement research.

Authors

Felix Poppelaars, V. Michael Holers, Joshua M. Thurman

×

Abstract

The complement system is a highly conserved and essential immune component with pivotal roles in innate and adaptive immunity. It is increasingly recognized that the complement system has a profound impact on disease. Current complement-targeting therapeutics for clinical use almost exclusively target the complement system in circulation. However, recent discoveries have demonstrated that complement is not only liver derived and plasma operative, but also synthesized and activated inside many cells locally within tissues, performing noncanonical, cell-autonomous intracellular functions, collectively referred to as the complosome. These intracellular complement pathways are distinct from the classical plasma-based system and critical for regulating fundamental cellular processes, including metabolism, gene transcription, autophagy, and the activation and resolution of inflammation. This Review explores the emerging roles of the complosome and current knowledge regarding its relation to human diseases, highlighting evidence across organ systems and disease states, including the kidneys, digestive tract, lungs, heart, CNS, musculoskeletal system, skin, and cancer. We also review current scientific approaches for detecting and functionally investigating the complosome, addressing challenges such as technological limitations and the need for advanced experimental models to delineate its tissue-specific roles. Finally, we discuss central unanswered questions critical for developing innovative therapeutic strategies targeting intracellular complement pathways. These strategies hold potential to modulate disease-specific mechanisms while preserving systemic complement activity.

Authors

Tilo Freiwald, Behdad Afzali

×
Commentaries
Abstract

Bardet-Biedl syndrome (BBS) is a complex genetic condition that can affect multiple organ systems, frequently causing pigmentary retinopathy, renal abnormalities, polydactyly, and obesity. Metabolic disturbances including obesity, unsuppressed appetite, and an increased risk of type 2 diabetes (T2D) present clinical management challenges. In this issue of the JCI, Singh et al. present a mouse model of a specific BBS subtype with genetic deletion of the Bbs5 gene. The model recapitulates many of the clinical features observed in patients living with BBS5 and sheds light on adipocyte biology, as well as the hypothalamic mechanisms driving hunger- and food-seeking behaviors that fuel the adverse metabolic phenotype. Importantly, exogenous GLP-1 receptor agonist treatment suppressed both appetite and weight, opening opportunities for direct translation into the clinical setting.

Authors

Jeremy W. Tomlinson

×

Abstract

Microglia play critical roles in immune defense within the central nervous system (CNS), and microglia-mediated immune changes in the brain are observed in various neurodegenerative diseases, including Parkinson’s disease (PD). While PET imaging with a range of radiolabeled ligands has been invaluable for visualizing and quantifying neuroimmune changes in the brains of patients with PD, no PET ligands currently exist that are specific to microglia. In this issue of the JCI, Mills et al. used the PET radioligand [¹¹C]CPPC to image colony stimulating factor 1 receptor (CSF1R), revealing a connection between increased CSF1R expression and microglia-mediated brain immune changes in patients with PD. The study demonstrated that elevated CSF1R expression colocalized with a microglial-specific marker in brain regions vulnerable to PD. Moreover, quantifying CSF1R density with [¹¹C]CPPC-PET imaging in living brains may provide an indicator of motor and cognitive impairments in the early stages of PD. These findings underscore the potential of CSF1R-PET imaging as a microglial-sensitive biomarker of brain immune function in PD.

Authors

So Jeong Lee, Changning Wang, Jacob Hooker

×

Abstract

Uromodulin is the most abundant protein in human urine, playing diverse roles, from providing frontline defense against uropathogens to regulating electrolyte balance via modulation of ion channels and cotransporters. In this issue of the JCI, Nanamatsu et al. unveil an alternatively spliced isoform of uromodulin that was dynamically induced in response to oxidative stress and tubular injury. Unlike the canonical secreted form, this isoform was retained in the cell, where it interacted with solute carrier proteins primarily localized to the mitochondrial membrane. Through these interactions, it modulated mitochondrial energetics and enhanced tubular cell resilience to injury. These findings broaden our understanding of uromodulin’s multifaceted functions, uncover an adaptive mechanism by which the kidney responds to cellular stress, and open avenues for therapeutic strategies targeting kidney injury and repair.

Authors

Ronak Lakhia, Chunzi Song, Vishal Patel

×

Abstract

The effect of food intake patterns on growth remain largely unknown. In this issue of the JCI, Hornsby et al. provide compelling evidence that, in young males, confining food intake to three meals a day entrains preprandial ghrelin release, leading to postprandial growth hormone pulse release that is associated with an increase in epiphysial plate expansion — a measure indicative of increased bone growth. The positive effects of discrete meal intake, on bone, was dependent on an intact ghrelin signaling system. This Commentary posits that meal-entrained ghrelin release may enhance skeletal accrual, whether through direct action on bone cells, via stimulation of growth hormone secretion, or in concert with other nutrient-responsive hormones. Coordinating these hormonal cues with food intake could maximize bone acquisition and improve bone health throughout the lifespan.

Authors

Rhonda D. Kineman, Shoshana Yakar

×
Research Letters
Research Articles
Abstract

Patients with systemic lupus erythematosus (SLE) are photosensitive, developing skin inflammation with even ambient ultraviolet radiation (UVR), and this cutaneous photosensitivity can be associated with UVR-induced flares of systemic disease, which can involve increased autoantibodies and further end-organ injury. Mechanistic insight into the link between the skin responses and autoimmunity is limited. Signals from skin are transmitted directly to the immune system via lymphatic vessels, and here we show evidence for potentiation of UVR-induced lymphatic flow dysfunction in SLE patients and murine models. Improving lymphatic flow by manual lymphatic drainage (MLD) or with a transgenic model with increased lymphatic vessels reduces both cutaneous inflammation and lymph node B and T cell responses, and long-term MLD reduces splenomegaly and titers of a number of autoantibodies. Mechanistically, improved flow restrains B cell responses in part by stimulating a lymph node fibroblastic reticular cell-monocyte axis. Our results point to lymphatic modulation of lymph node stromal function as a link between photosensitive skin responses and autoimmunity and as a therapeutic target in lupus, provide insight into mechanisms by which the skin state regulates draining lymph node function, and suggest the possibility of MLD as an accessible and cost-effective adjunct to add to ongoing medical therapies for lupus and related diseases.

Authors

Mir J. Howlader, William G. Ambler, Madhavi Latha S. Chalasani, Aahna Rathod, Ethan S. Seltzer, Ji Hyun Sim, Jinyeon Shin, Noa Schwartz, William D. Shipman III, Dragos C. Dasoveanu, Camila B. Carballo, Ecem Sevim, Salma Siddique, Yurii Chinenov, Scott A. Rodeo, Doruk Erkan, Raghu P. Kataru, Babak J. Mehrara, Theresa T. Lu

×

Abstract

Colistin (COL) is a cationic cyclic peptide that disrupts the membranes of Gram-negative bacteria and is often used as a last resort antibiotic against multidrug-resistant strains. The emergence of plasmid-borne mcr genes, which confer transferable COL resistance, has raised serious concerns, particularly in strains also carrying extended-spectrum β-lactamase and carbapenemase genes. Standard antimicrobial susceptibility testing (AST), performed in enriched bacteriological media, indicates no activity of COL against mcr+ strains, leading to its exclusion from treatment regimens. However, these media poorly reflect in vivo physiology and lack host immune components. Here we show that COL retained bactericidal activity against mcr-1+ Escherichia coli, Klebsiella pneumoniae, and Salmonella enterica when tested in tissue culture medium containing physiological bicarbonate. COL enhanced serum complement deposition on bacterial surfaces and synergized with human serum to kill pathogens. At clinically achievable concentrations, COL killed mcr-1+ strains in freshly isolated human blood and was effective as monotherapy in a murine E. coli bacteremia model. These findings suggest that COL, currently dismissed based on conventional AST, may offer clinical benefit against mcr-1+ infections when evaluated under more physiological conditions — warranting reconsideration in clinical microbiology practices and future trials for high-risk patients.

Authors

Monika Kumaraswamy, Angelica Montenegro Riestra, Anabel Flores, Samira Dahesh, Fatemeh Askarian, Satoshi Uchiyama, Jonathan Monk, Sean Jung, Gunnar Bondsäter, Victoria Nilsson, Melanie Chang, Jüergen B. Bulitta, Yinzhi Lang, Armin Kousha, Elisabet Bjånes, Natalie Chavarria, Ty’Tianna Clark, Hideya Seo, George Sakoulas, Victor Nizet

×

Abstract

Weight loss medications are emerging candidates for pharmacotherapy of sleep-disordered breathing (SDB). A melanocortin 4 receptor (MC4R) agonist, setmelanotide (Set), is used to treat obesity caused by abnormal melanocortin and leptin signaling. We hypothesized that Set can treat SDB in mice with diet-induced obesity. We performed a proof-of-concept randomized crossover trial of a single dose of Set versus vehicle and a 2-week daily Set versus vehicle trial, examined colocalization of Mc4r mRNAs with the markers of CO2-sensing neurons Phox2b and neuromedin B in the brainstem, and expressed Cre-dependent designer receptors exclusively activated by designer drugs (DREADDs) or caspase in obese Mc4r-Cre mice. Set increased minute ventilation across sleep/wake states, enhanced the hypercapnic ventilatory response (HCVR), and abolished apneas during sleep. Phox2b+ neurons in the nucleus of the solitary tract (NTS) and the parafacial region expressed Mc4r. Chemogenetic stimulation of the MC4R+ neurons in the parafacial region, but not in the NTS, augmented HCVR without any changes in metabolism. Caspase elimination of the parafacial MC4R+ neurons abolished effects of Set on HCVR. Parafacial MC4R+ neurons projected to the respiratory premotor neurons retrogradely labeled from C3–C4. In conclusion, MC4R agonists enhance the HCVR and treat SDB by acting on the parafacial MC4R+ neurons.

Authors

Mateus R. Amorim, Noah R. Williams, O. Aung, Melanie Alexis Ruiz, Frederick Anokye-Danso, Junia L. de Deus, Jiali Xiong, Olga Dergacheva, Shannon Bevans-Fonti, Sean M. Lee, Jeffrey S. Berger, Mark N. Wu, Rexford S. Ahima, David Mendelowitz, Vsevolod Y. Polotsky

×

Abstract

Cancer cachexia is a multifactorial condition characterized by skeletal muscle wasting that impairs quality of life and longevity for many cancer patients. A greater understanding of the molecular etiology of this condition is needed for effective therapies to be developed. We performed a quantitative proteomic analysis of skeletal muscle from cachectic pancreatic ductal adenocarcinoma (PDAC) patients and non-cancer controls, followed by immunohistochemical analyses of muscle cross sections. These data provide evidence of a local inflammatory response in muscles of cachectic PDAC patients, including an accumulation of plasma proteins and recruitment of immune cells into muscle that may promote the pathological remodeling of muscle. Our data further support the complement system as a potential mediator of these processes, which we tested by injecting murine pancreatic cancer cells into wild-type mice and mice with genetic deletion of the central complement component 3 (C3–/– mice). Compared with wild-type mice, C3–/– mice showed attenuated tumor-induced muscle wasting and dysfunction and reduced immune cell recruitment and fibrotic remodeling of muscle. These studies demonstrate that complement activation contributes to the skeletal muscle pathology and dysfunction in PDAC, suggesting that the complement system may possess therapeutic potential in preserving skeletal muscle mass and function.

Authors

Andrew C. D’Lugos, Jeremy B. Ducharme, Chandler S. Callaway, Jose G. Trevino, Carl Atkinson, Sarah M. Judge, Andrew R. Judge

×

Abstract

Diffuse midline gliomas (DMGs) are lethal brain tumors characterized by p53-inactivating mutations and oncohistone H3.3K27M mutations that rewire the cellular response to genotoxic stress. We used RCAS/tv-a retroviruses and Cre recombinase to inactivate p53 and induce native H3.3K27M mutations in a lineage- and spatially directed manner. We generated primary mouse tumors that recapitulated human DMG. Disrupting ataxia-telangiectasia mutated (ATM) kinase enhanced the efficacy of radiation therapy (RT) in murine and patient-derived DMG models and increased survival. Microscopy-based in situ sequencing was used to spatially resolve transcriptional profiles in more than 750,000 single cells with or without ATM disruption and RT, revealing altered immune-neoplastic and endothelial cell interactions after treatment. An allelic series of primary murine DMG models with different p53 mutations confirmed that transactivation-independent p53 activity was a key mediator of radiosensitivity after ATM disruption. We generated primary DMG mouse models and performed deep profiling that revealed mechanisms of response to ATM disruption and RT that can be utilized as a therapeutic strategy.

Authors

Avani Mangoli, Vennesa Valentine, Spencer M. Maingi, Sophie R. Wu, Harrison Q. Liu, Michael Aksu, Vaibhav Jain, Bronwen E. Foreman, Joshua A. Regal, Loren B. Weidenhammer, Connor E. Stewart, Maria E. Guerra Garcia, Emily Hocke, Karen Abramson, Tal Falick Michaeli, Nerissa T. Williams, Lixia Luo, Megan Romero, Katherine Deland, Samantha Gadd, Eita Uchida, Laura Attardi, Kouki Abe, Rintaro Hashizume, David M. Ashley, Oren J. Becher, David G. Kirsch, Simon G. Gregory, Zachary J. Reitman

×

Abstract

GM1 gangliosidosis is a lysosomal storage disorder (LSD) caused by genetic defects in lysosomal β-galactosidase (β-gal). The primary substrate of β-gal is GM1 ganglioside (GM1), a sialylated glycosphingolipid abundant in the central nervous system (CNS). Deficiency in β-gal causes GM1 to accumulate in neural cells, leading to a rapid decline in psychomotor functions, seizures, and premature death. There is currently no therapy available. Although enzyme replacement therapy has been approved for other LSDs, its effects on the CNS are limited owing to the blood-brain barrier (BBB). Here, we assessed the therapeutic efficacy of a systemic infusion of an adeno-associated virus vector carrying a gene expressing a BBB-penetrable enzyme under the control of a liver-specific promoter in GM1 gangliosidosis model mice. The BBB-penetrable enzyme consisted of the variable region of the anti–transferrin receptor antibody fused with β-gal. The BBB-penetrable enzyme was only produced in the liver and secreted into the blood, which was efficiently distributed to various organs, including the brain. GM1 accumulation in the CNS was completely normalized, with improved neurological functions and animal survival. This therapeutic approach is expected to be applied for the treatment of several hereditary neurological diseases with CNS involvement.

Authors

Saki Kondo Matsushima, Yohta Shimada, Masafumi Kinoshita, Takashi Nagashima, Shinichiro Okamoto, Sayoko Iizuka, Haruna Takagi, Shunsuke Iizuka, Takashi Higuchi, Hiroyuki Hioki, Ayako M. Watabe, Hiroyuki Sonoda, Toya Ohashi, Hiroshi Kobayashi

×

Abstract

BACKGROUND Tebentafusp is the first T cell receptor–based bispecific protein approved for clinical use in HLA-A*02:01+ adult patients with unresectable/metastatic uveal melanoma. It redirects T cells toward gp100-expressing target cells, frequently inducing skin-related early adverse events.METHODS This study investigated immunological and cellular responses using single-cell and spatial analysis of skin biopsies from patients with metastatic uveal melanoma treated with tebentafusp.RESULTS 81.8% of patients developed acute cutaneous adverse events, which correlated with improved survival. Multimodal analysis revealed a brisk infiltration of CD4+ and CD8+ T cells, while melanocyte numbers declined. Single-cell RNA-sequencing revealed T cell activation, proliferation, and IFN-γ/cytotoxic gene upregulation. CD8+ T cells colocalized with melanocytes and upregulated LAG3, suggesting potential for combination therapies with tebentafusp. Melanocytes upregulated antigen presentation and apoptotic pathways, while pigmentation gene expression decreased. However, gp100 remained stably expressed.CONCLUSION Sequential skin biopsies enable in vivo pharmacodynamic modeling of tebentafusp, offering insights into immune activation, toxicity, and treatment response. Examining the on-target effects of bispecifics in tissues amenable to longitudinal sampling enhances our understanding of toxicity and therapeutic escape mechanisms, guiding strategies for treatment optimization.FUNDING Cancer Research Foundation, Swiss National Science Foundation (323630_207029, 733 310030_170320, 310030_188450, CRSII5_183478), Iten-Kohaut Foundation, European Research Council no. 882424, University Priority Project Translational Cancer Research of the University of Zurich (UZH), UZH PostDoc grant (K-85810-02-01).

Authors

Ramon Staeger, Aizhan Tastanova, Adhideb Ghosh, Nicola Winkelbeiner, Prachi Shukla, Isabel Kolm, Patrick Turko, Adel Benlahrech, Jane Harper, Anna Broomfield, Antonio Camera, Marianna Ambrosio, Veronika Haunerdinger, Phil F. Cheng, Egle Ramelyte, James Pham, Stefanie Kreutmair, Burkhard Becher, Mitchell P. Levesque, Reinhard Dummer, Barbara Meier-Schiesser

×

Abstract

The efficacy of T cell–activating therapies against glioma is limited by an immunosuppressive tumor microenvironment and tumor-induced T cell sequestration. We investigated whether peripherally infused nonantigen specific autologous lymphocytes could accumulate in intracranial tumors. We observed that nonspecific autologous CD8+ ALT cells can indeed accumulate in this context, despite endogenous T cell sequestration in bone marrow. Rates of intratumoral accumulation were markedly increased when expanding lymphocytes with IL-7 compared with IL-2. Pretreatment with IL-7 ALT also enhanced the efficacy of multiple tumor-specific and nontumor-specific T cell–dependent immunotherapies against orthotopic murine and human xenograft gliomas. Mechanistically, we detected increased VLA-4 on mouse and human CD8+ T cells following IL-7 expansion, with increased transcription of genes associated with migratory integrin expression (CD9). We also observed that IL-7 increases S1PR1 transcription in human CD8+ T cells, which we have shown to be protective against tumor-induced T cell sequestration. These observations demonstrate that expansion with IL-7 enhances the capacity of ALT to accumulate within intracranial tumors and that pretreatment with IL-7 ALT can boost the efficacy of subsequent T cell–activating therapies against glioma. Our findings will inform the development of future clinical trials where ALT pretreatment can be combined with T cell–activating therapies.

Authors

Kirit Singh, Kelly M. Hotchkiss, Sarah L. Cook, Pamy Noldner, Ying Zhou, Eliese M. Moelker, Chelsea O. Railton, Emily E. Blandford, Bhairavy J. Puviindran, Shannon E. Wallace, Pamela K. Norberg, Gary E. Archer, Beth H. Shaz, Katayoun Ayasoufi, John H. Sampson, Mustafa Khasraw, Peter E. Fecci

×

Abstract

BACKGROUND Decoding the clinical impact of genetic variants is particularly important for precision medicine in cancer. Genetic screening of mainly patients with breast and ovarian cancer has identified numerous BRCA1/BRCA2 variants of uncertain significance (VUS) that remain unclassified owing to a lack of pedigrees and functional data.METHODS Here, we used CRISPR-Select — a technology that exploits unique inbuilt controls at the endogenous locus — to assess 54 rare ClinVar VUS located in the PALB2-binding domain of BRCA2. Variant deleteriousness was examined in the absence and presence of PARPi, cisplatin, or mitomycin C.RESULTS Marked functional deficiency was observed for variants in the exon 2 donor splice region (A22 = c.66A>C, A22 = c.66A>G, A22 = c.66A>T, and D23H) and Trp31 aa (W31G, W31L, and W31C), both critical for BRCA2 function. Moreover, T10K and G25R resulted in an intermediate phenotype, suggesting these variants are hypomorphic in nature. Combining our functional results with the latest ClinGen BRCA1/2 Variant Curation Expert Panel recommendations, we classified 49 of the 54 VUS as either likely benign (n = 45) or likely pathogenic (n = 4).CONCLUSION Therefore, CRISPR-Select is an important tool for efficient variant clinical classification. Application of this technology in the future will ultimately improve patient care.FUNDING Danish Cancer Society, Novo Nordisk Foundation, Sygeforsikring Danmark, Børnecancerfonden, Neye-Fonden, Roche, Novartis, Pfizer, AstraZeneca, MSD, and Daiichi Sankyo Europe GmbH.

Authors

Muthiah Bose, Manika Indrajit Singh, Morten Frödin, Bent Ejlertsen, Claus S. Sørensen, Maria Rossing

×

Abstract

In the kidney, cells of thick ascending limb of the loop of Henle (TAL) are resistant to ischemic injury, despite high energy demands. This adaptive metabolic response is not fully understood even though the integrity of TAL cells is essential for recovery from acute kidney injury (AKI). TAL cells uniquely express uromodulin, the most abundant protein secreted in healthy urine. Here, we demonstrate that alternative splicing generates a conserved intracellular isoform of uromodulin, which contributes to metabolic adaptation of TAL cells. This splice variant was induced by oxidative stress and was upregulated by AKI that is associated with recovery, but not by severe AKI and chronic kidney disease (CKD). This intracellular variant was targeted to the mitochondria, increased NAD+ and ATP levels, and protected TAL cells from hypoxic injury. Augmentation of this variant using antisense oligonucleotides after severe AKI improved the course of injury. These findings underscore an important role of condition-specific alternative splicing in adaptive energy metabolism to hypoxic stress. Enhancing this protective splice variant in TAL cells could become a therapeutic intervention for AKI.

Authors

Azuma Nanamatsu, George J. Rhodes, Kaice A. LaFavers, Radmila Micanovic, Virginie Lazar, Shehnaz Khan, Daria Barwinska, Shinichi Makino, Amy Zollman, Ying-Hua Cheng, Emma H. Doud, Amber L. Mosley, Matthew J. Repass, Malgorzata M. Kamocka, Aravind Baride, Carrie L. Phillips, Katherine J. Kelly, Michael T. Eadon, Jonathan Himmelfarb, Matthias Kretzler, Robert L. Bacallao, Pierre C. Dagher, Takashi Hato, Tarek M. El-Achkar

×

Abstract

Gestational hypertension (GH) is prevalent, with life-long health burdens for mothers and their children exposed in utero. We analyzed the nation-wide Epic Cosmos dataset and found significantly higher rates of seizures in children of mothers with GH than in children of normotensive mothers. Complementary studies of nested Iowa and Stanford cohorts and a large Taiwanese cohort also revealed significantly increased seizure risk after covariate adjustments. We modeled this association in an angiotensin (ANG) II mouse model of GH. Maternal ANG II significantly increased seizure grade and deaths elicited by pilocarpine among male but not female offspring. Electrical stimulation increased seizure grade and death across sexes in offspring from ANG II–treated dams. Proinflammatory and microglial gene expression in the brain were upregulated only in male offspring from ANG II–treated dams. Chronic phenylephrine, a GH model lacking the maternal proinflammatory aspects of ANG II, induced similar offspring seizure phenotypes. PLX5622-induced depletion of microglia or antiinflammatory pentoxifylline abolished this sensitized seizure response and lowered mortality in the ANG II model. These results suggest that GH programs offspring risk for seizures in a sex-dependent manner in humans and mice. Neuroinflammatory mechanisms may contribute to the elevated sensitivity and mortality from seizures elicited by GH exposure in utero.

Authors

Baojian Xue, Serena B. Gumusoglu, Grant Tiarks, Brittany P. Todd, Angela Wong, Donna A. Santillan, Chin-Chi Kuo, Hsiu-Yin Chiang, Rohith Ravindranath, Sophia Y. Wang, Vinit B. Mahajan, Alan Kim Johnson, Heath A. Davis, Polly Ferguson, Elizabeth A. Newell, Mark K. Santillan, Jason M. Misurac, Alexander G. Bassuk

×

Abstract

Hormone receptor–positive and human epidermal growth factor receptor 2–negative breast cancer (HR+/HER2− BC) is the most common subtype, with a high risk of long-term recurrence and metastasis. Endocrine therapy (ET) combined with cyclin-dependent kinase 4/6 (CDK4/6) inhibitors is a standard treatment for advanced/metastatic HR+/HER2– BC, but resistance remains a major clinical challenge. We report that kinesin family member C2 (KIFC2) was amplified in approximately 50% of patients with HR+/HER2– BC, and its high expression was associated with poor disease outcome, increased tumor protein p53 (TP53) somatic mutation, and active pyrimidine metabolism. Functional assays revealed that depletion of KIFC2 suppressed growth and enhanced sensitivity of HR+/HER2– BC cells to tamoxifen and CDK4/6 inhibitors. Mechanistically, KIFC2 stabilized CDK4 by enhancing its interaction with ubiquitin-specific peptidase 9 X-linked (USP9X). Importantly, reexpression of CDK4 in KIFC2-depleted cells partially rescued the decreased growth and increased sensitivity to tamoxifen and CDK4/6 inhibitors caused by KIFC2 depletion. Clinically, high KIFC2 mRNA expression was negatively associated with the survival rate of patients with HR+/HER2– BC who received adjuvant ET alone or in combination with CDK4/6 inhibitors. Collectively, these findings identify an important role for KIFC2 in HR+/HER2– BC growth and therapeutic resistance, and support its potential as a therapeutic target and predictive biomarker.

Authors

Shao-Ying Yang, Ming-Liang Jin, Lisa Andriani, Qian Zhao, Yun-Xiao Ling, Cai-Jin Lin, Min-Ying Huang, Jia-Yang Cai, Yin-Ling Zhang, Xin Hu, Zhi-Ming Shao, Fang-Lin Zhang, Xi Jin, A Yong Cao, Da-Qiang Li

×

Abstract

The nucleolus is a membraneless organelle and an excellent stress sensor. Any changes in its architecture or composition lead to nucleolar stress, resulting in cell cycle arrest and interruption of ribosomal activity, critical factors in aging and cancer. In this study, we identified and described the pivotal role of the RNA-binding protein HNRNPK in ribosome and nucleolar dynamics. We developed an in vitro model of endogenous HNRNPK overexpression and an in vivo mouse model of ubiquitous HNRNPK overexpression. These models showed disruptions in translation as the HNRNPK overexpression caused alterations in the nucleolar structure, resulting in p53-dependent nucleolar stress, cell cycle arrest, senescence, and bone marrow failure phenotype, similar to what is observed in patients with ribosomopathies. Together, our findings identify HNRNPK as a master regulator of ribosome biogenesis and nucleolar homeostasis through p53, providing what we believe to be a new perspective on the orchestration of nucleolar integrity, ribosome function and cellular senescence.

Authors

Pedro Aguilar-Garrido, María Velasco-Estévez, Miguel Ángel Navarro-Aguadero, Álvaro Otero-Sobrino, Marta Ibáñez-Navarro, Miguel Ángel Marugal, María Hernández-Sánchez, Prerna Malaney, Ashley Rodriguez, Oscar Benitez, Xiaroui Zhang, Marisa J.L. Aitken, Alejandra Ortiz-Ruiz, Diego Megías, Manuel Pérez, Gadea Mata, Jesús Gomez, Miguel Lafarga, Orlando Domínguez, Osvaldo Graña-Castro, Eduardo Caleiras, Pilar Ximénez-Embun, Marta Isasa, Paloma Jimena de Andres, Sandra Rodríguez-Perales, Raúl Torres-Ruiz, Enrique Revilla, Rosa María García-Martín, Daniel Azorín, Josune Zubicaray, Julián Sevilla, Oleksandra Sirozh, Vanesa Lafarga, Joaquín Martínez-López, Sean M. Post, Miguel Gallardo

×

Abstract

Bardet-Biedl syndrome (BBS), a ciliopathy characterized by obesity, hyperphagia, and learning deficits, arises from mutations in Bbs genes. Exacerbated symptoms occur with mutations in genes encoding the BBSome, a complex regulating primary cilia function. We investigated the mechanisms underlying BBS-induced obesity using a Bbs5-knockout (Bbs5–/–) mouse model. Bbs5–/– mice were characterized by hyperphagia, learning deficits, glucose/insulin intolerance, and disrupted metabolic hormones, phenocopying human BBS. White adipose tissue in these mice had a unique immunophenotype, with increased proinflammatory macrophages and dysfunctional Tregs, suggesting a mechanism for adiposity distinct from those of typical obesity models. Additionally, Bbs5–/– mice exhibited pancreatic islet hyperplasia but failed to normalize blood glucose, suggesting defective insulin action. Hypothalamic transcriptomics revealed dysregulation of endocrine signaling pathways, with functional analyses confirming defects in insulin, leptin, and cholecystokinin (CCK) signaling, while glucagon-like peptide-1 receptor (GLP-1R) responsiveness was preserved. Notably, treatment with a GLP-1RA effectively alleviated hyperphagia and body weight gain, improved glucose tolerance, and regulated circulating metabolic hormones in Bbs5–/– mice. This study suggests that Bbs5–/– mice represent a valuable translational model of BBS for understanding pathogenesis and developing better treatments. Our findings highlight the therapeutic potential of GLP-1RAs for managing BBS-associated metabolic dysregulation, indicating that further investigation for clinical application is warranted.

Authors

Arashdeep Singh, Naila Haq, Mingxin Yang, Shelby Luckey, Samira Mansouri, Martha Campbell-Thompson, Lei Jin, Sofia Christou-Savina, Guillaume de Lartigue

×

Abstract

Castration-resistant prostate cancer (CRPC) marks the advanced and lethal stage of prostate cancer (PCa). TRIM28, also known as KAP1, is a transcriptional regulator recently shown to promote CRPC cell proliferation and xenograft tumor growth. Nonetheless, knowledge gaps persist regarding the mechanisms underlying TRIM28 upregulation in CRPC as well as the genomic targets regulated by TRIM28. Here, we report that TRIM28 is a E2F1 target in CRPC. Using an integrated genomic approach, we have demonstrated that TRIM28 forms a positive feedback loop to promote the transcriptional activation and genomic function of E2F1 independent of retinoblastoma (Rb) status. Furthermore, we identified RSK1 as a kinase that directly phosphorylates TRIM28 at S473, and, as such, RSK1 drives the TRIM28/E2F1 feedback loop. Accordingly, pS473-TRIM28 promotes CRPC progression, which is mitigated by RSK inhibition. In summary, our study reveals a critical role of the RSK1–TRIM28–E2F1 axis in CRPC progression, which may be exploited as a vulnerability in treating Rb-deficient CRPC.

Authors

Miyeong Kim, Jinpeng Liu, Yanquan Zhang, Ruixin Wang, Ryan Goettl, Jennifer Grasso, Derek B. Allison, Chi Wang, Tianyan Gao, Xiaoqi Liu, Ka-Wing Fong

×

Abstract

As antimicrobial resistance rises, new antibacterial candidates are urgently needed. Using sequence space information from over 14,743 functional antimicrobial peptides (AMPs), we improved the antimicrobial properties of citropin 1.1, an AMP with weak antimethicillin resistant Staphylococcus aureus (MRSA) activity, producing a short and potent antistaphylococcal peptide, CIT-8 (13 residues). At 40 μg/mL, CIT-8 eradicated 1 × 108 drug-resistant MRSA and vancomycin resistant S. aureus (VRSA) persister cells within 30 minutes of exposure and reduced the number of viable biofilm cells of MRSA and VRSA by 3 log10 and 4 log10 in established biofilms, respectively. CIT-8 (at 32 μg/mL) depolarized and permeated the S. aureus MW2 membrane. In a mouse model of MRSA skin infection, CIT-8 (2% w/w in petroleum jelly) significantly reduced the bacterial burden by 2.3 log10 (P < 0.0001). Our methodology accelerated AMP design by combining traditional peptide design strategies, such as truncation, substitution, and structure-guided alteration, with machine learning–backed sequence optimization.

Authors

Biswajit Mishra, Anindya Basu, Fadi Shehadeh, LewisOscar Felix, Sai Sundeep Kollala, Yashpal Singh Chhonker, Mandar T. Naik, Charilaos Dellis, Liyang Zhang, Narchonai Ganesan, Daryl J. Murry, Jianhua Gu, Michael B. Sherman, Frederick M. Ausubel, Paul P. Sotiriadis, Eleftherios Mylonakis

×

Abstract

BACKGROUND Microglia-mediated brain immune changes play a role in the pathogenesis of Parkinson’s disease (PD), but imaging microglia in living people with PD has relied on positron emission tomography (PET) ligands that lack specificity in labeling immune cells in the nervous system. We aimed to develop imaging of colony stimulating factor 1 receptor (CSF1R) as a microglial-sensitive marker of innate immunity.METHODS IHC using a CSF1R antibody evaluated colocalization with Iba-1 in PD (n = 4) and control (n = 4) human brain samples. Autoradiography using a CSF1R tritiated ligand in human brain samples from individuals with PD (n = 5) and in a control group (n = 4) was performed to obtain Bmax. PET imaging using a CSF1R radioligand was performed in 10 controls and 12 people with PD, and VT was compared between groups and correlated with disease severity.RESULTS IHC of CSF1R in human brain samples shows colocalization with Iba-1 and is significantly increased in brain samples from individuals with PD compared with individuals in a control group. Autoradiography revealed significantly increased CSF1R ligand binding in the inferior parietal cortex of patients with PD. [11C]CPPC PET showed higher binding in people with moderate PD compared with people in a control group and ligand binding correlated with more severe motor disability and poorer verbal fluency.CONCLUSION This study underscores the significance of CSF1R imaging as a promising biomarker for brain immune function in Parkinson’s disease, which may be associated with cognitive and motor disease severity.FUNDING PET imaging: the Michael J. Fox Foundation and the RMS Family Foundation. Radiotracer development: NIH (R01AG066464 and P41 EB024495). Postmortem brain tissues: NIH P30 AG066507 and BIOCARD study NIH U19 AG033655.

Authors

Kelly A. Mills, Yong Du, Jennifer M. Coughlin, Catherine A. Foss, Andrew G. Horti, Katelyn R. Jenkins, Yana Skorobogatova, Ergi Spiro, Chelsie S. Motley, Robert F. Dannals, Wojciech G. Lesniak, Jae-Jin Song, Yu Ree Choi, Javier Redding-Ochoa, Juan C. Troncoso, Valina L. Dawson, Tae-In Kam, Martin G. Pomper, Ted M. Dawson

×

Abstract

Myxomatous valve disease (MVD) is the most common form of cardiac valve disease in the developed world. A small fraction of MVD is syndromic and arises in association with matrix protein defects such as those in Marfan syndrome, but most MVD is acquired later in life through an undefined pathogenesis. The KLF2/4 transcription factors mediate endothelial fluid shear responses, including those required to create cardiac valves during embryonic development. Here we test the role of hemodynamic shear forces and downstream endothelial KLF2/4 in mature cardiac valves. We find that loss of hemodynamic forces in heterotopically transplanted hearts or genetic deletion of KLF2/4 in cardiac valve endothelium confers valve cell proliferation and matrix deposition associated with valve thickening, findings also observed in mice expressing the mutant fibrillin-1 protein known to cause human MVD. Transcriptomic and histologic analysis reveals increased monocyte recruitment and TGF-β signaling in both fibrillin-1–mutant valves and valves lacking hemodynamic forces or endothelial KLF2/4 function, but only loss of TGF-β/SMAD signaling rescued myxomatous changes. We observed reduced KLF2/4 expression and augmented SMAD signaling in human MVD. These studies identify hemodynamic activation of endothelial KLF2/4 as an environmental homeostatic regulator of cardiac valves and suggest that non-syndromic MVD may arise in association with disturbed blood flow across the aging valve.

Authors

Jesse A. Pace, Lauren M. Goddard, Courtney C. Hong, Liqing Wang, Jisheng Yang, Mei Chen, Yitian Xu, Martin H. Dominguez, Siqi Gao, Xiaowen Chen, Patricia Mericko-Ishizuka, Can Tan, Tsutomu Kume, Wenbao Yu, Kai Tan, Wayne W. Hancock, Giovanni Ferrari, Mark L. Kahn

×

Abstract

The physiological effect of ultradian temporal feeding patterns remains a major unanswered question in nutritional science. We have used automated and nasogastric feeding to address this question in male rodents and human volunteers. While grazing and meal-feeding reduced food intake in parallel (compared with ad libitum–fed rodents), body length and tibial epiphysial plate width were maintained in meal-fed rodents via the action of ghrelin and its receptor, GHS-R. Grazing and meal-feeding initially suppressed elevated preprandial ghrelin levels in rats, followed by either a sustained elevation in ghrelin in grazing rats or preprandial ghrelin surges in meal-fed rats. Episodic growth hormone (GH) secretion was largely unaffected in grazing rats, but meal-feeding tripled GH secretion, with burst height augmented and 2 additional bursts of GH per day. Continuous nasogastric infusion of enteral feed in humans failed to suppress circulating ghrelin, producing continuously elevated circulating GH levels with minimal rhythmicity. In contrast, bolus enteral infusion elicited postprandial ghrelin troughs accompanied by reduced circulating GH, with enhanced ultradian rhythmicity. Taken together, our data imply that the contemporary shift from regular meals to snacking behavior may be detrimental to optimal skeletal growth outcomes by sustaining circulating ghrelin at levels associated with undernourishment and diminishing GH pulsatility.

Authors

Amanda K.E. Hornsby, Richard C. Brown, Thomas W. Tilston, Harry A. Smith, Alfonso Moreno-Cabañas, Bradley Arms-Williams, Anna L. Hopkins, Katie D. Taylor, Simran K.R. Rogaly, Lois H.M. Wells, Jamie J. Walker, Jeffrey S. Davies, Yuxiang Sun, Jeffrey M. Zigman, James A. Betts, Timothy Wells

×

Abstract

The presence of B cells is essential for the formation of CD8+ T cell memory after infection and vaccination. In this study, we investigated whether B cells influence the programming of naive CD8+ T cells prior to their involvement in an immune response. RNA sequencing indicated that B cells are necessary for sustaining the FOXO1-controlled transcriptional program, which is critical for homeostasis of these T cells. Without an appropriate B cell repertoire, mouse naive CD8+ T cells exhibit a terminal, effector-skewed phenotype, which significantly impacts their response to vaccination. A similar effector-skewed phenotype with reduced FOXO1 expression was observed in naive CD8+ T cells from human patients undergoing B cell–depleting therapies. Furthermore, we show that patients without B cells have a defect in generating long-lived CD8+ T cell memory following COVID vaccination. In summary, we demonstrate that B cells promote the quiescence of naive CD8+ T cells, poising them to become memory cells upon vaccination.

Authors

Cameron Manes, Miguel Guerrero Moreno, Jennifer Cimons, Marc A. D’Antonio, Tonya M. Brunetti, Michael G. Harbell, Sean Selva, Christopher Mizenko, Tyler L. Borko, Erika L. Lasda, Jay R. Hesselberth, Elena W.Y. Hsieh, Michael R. Verneris, Amanda L. Piquet, Laurent Gapin, Ross M. Kedl, Jared Klarquist

×

Abstract

The progression of metabolic dysfunction–associated steatotic liver disease (MASLD) to metabolic dysfunction–associated steatohepatitis (MASH) involves alterations in both liver-autonomous and systemic metabolism that influence the liver’s balance of fat accretion and disposal. Here, we quantify the contributions of hepatic oxidative pathways to liver injury in MASLD-MASH. Using NMR spectroscopy, UHPLC-MS, and GC-MS, we performed stable isotope tracing and formal flux modeling to quantify hepatic oxidative fluxes in humans across the spectrum of MASLD-MASH, and in mouse models of impaired ketogenesis. In humans with MASH, liver injury correlated positively with ketogenesis and total fat oxidation, but not with turnover of the tricarboxylic acid cycle. Loss-of-function mouse models demonstrated that disruption of mitochondrial HMG-CoA synthase (HMGCS2), the rate-limiting step of ketogenesis, impairs overall hepatic fat oxidation and induces an MASLD-MASH–like phenotype. Disruption of mitochondrial β-hydroxybutyrate dehydrogenase (BDH1), the terminal step of ketogenesis, also impaired fat oxidation, but surprisingly did not exacerbate steatotic liver injury. Taken together, these findings suggest that quantifiable variations in overall hepatic fat oxidation may not be a primary determinant of MASLD-to-MASH progression, but rather that maintenance of ketogenesis could serve a protective role through additional mechanisms that extend beyond overall rates of fat oxidation.

Authors

Eric D. Queathem, David B. Stagg, Alisa B. Nelson, Alec B. Chaves, Scott B. Crown, Kyle Fulghum, D. Andre d’Avignon, Justin R. Ryder, Patrick J. Bolan, Abdirahman Hayir, Jacob R. Gillingham, Shannon Jannatpour, Ferrol I. Rome, Ashley S. Williams, Deborah M. Muoio, Sayeed Ikramuddin, Curtis C. Hughey, Patrycja Puchalska, Peter A. Crawford

×

Abstract

Autosomal dominant optic atrophy (ADOA), the most prevalent hereditary optic neuropathy, leads to retinal ganglion cell (RGC) degeneration and vision loss. ADOA is primarily caused by mutations in the optic atrophy type 1 (OPA1) gene, which encodes a conserved GTPase important for mitochondrial inner membrane dynamics. To date, the disease mechanism remains unclear, and no therapies are available. We generated a mouse model carrying the pathogenic Opa1R290Q/+ allele that recapitulated key features of human ADOA, including mitochondrial defects, age-related RGC loss, optic nerve degeneration, and reduced RGC functions. We identified sterile alpha and TIR motif containing 1 (SARM1), a neurodegeneration switch, as a key driver of RGC degeneration in these mice. Sarm1 KO nearly completely suppressed all the degeneration phenotypes without reversing mitochondrial fragmentation. Additionally, we show that a portion of SARM1 localized within the mitochondrial intermembrane space. These findings indicated that SARM1 was activated downstream of mitochondrial dysfunction in ADOA, highlighting it as a promising therapeutic target.

Authors

Chen Ding, Papa S. Ndiaye, Sydney R. Campbell, Michelle Y. Fry, Jincheng Gong, Sophia R. Wienbar, Whitney Gibbs, Philippe Morquette, Luke H. Chao, Michael Tri H. Do, Thomas L. Schwarz

×

In-Press Preview - More

Abstract

Pro-inflammatory signaling in adipocytes is essential for healthy adipose expansion, remodeling, and tissue integrity. We investigated the effects of targeting inflammation in either adipocytes or mammary gland epithelial cells, in the context of mammary tumor development, by locally expressing the anti-inflammatory adenoviral RIDα/β protein complex in a cell type-specific manner. Suppression of adipocyte inflammation (“RIDad mice”) in a mammary tumor model driven by MMTV-PyMT (“PyMT-RIDad mice”) led to an elevated number of tumor-associated macrophages (TAMs) and upregulation of immunoregulatory molecules in the mammary fat pad (MFP). This was accompanied by metabolic dysfunction and abnormal mammary gland development. Importantly, this phenotype correlated with accelerated mammary tumor onset, enhanced growth, and lung metastasis. Tumors in PyMT-RIDad mice exhibited upregulated CD36 expression, suggesting enhanced fatty acid uptake. Conversely, suppression of inflammation in mammary gland epithelial cells by RIDα/β expression (“RIDMMTV mice”) decelerated mammary tumor growth without affecting tumor onset or macrophage accumulation. These findings highlight the differential impact on tumor development exerted through the suppression of inflammatory signals in different cell types in the microenvironment. Our results underscore the role of the suppression of adipocyte inflammation leading to a tumor-friendly microenvironment, promoting mammary cancer progression. This study sheds light on the complex interplay between inflammation, specifically driven by the adipocyte, in breast cancer pathogenesis.

Authors

Dae-Seok Kim, Toshiharu Onodera, Jan-Bernd Funcke, Kyounghee Min, Qingzhang Zhu, Qian Lin, Shiuhwei Chen, Chanmin Joung, Min Kim, R. Max Wynn, Joselin Velasco, Charlotte Lee, Megan Virostek, Chao Li, Philipp E. Scherer

×

Abstract

Atherosclerosis arises from disrupted cholesterol metabolism, notably impaired macrophage cholesterol efflux leading to foam cell formation. Through single-cell and bulk RNA sequencing, we identified Listerin as a regulator of macrophage cholesterol metabolism. Listerin expression increased during atherosclerosis progression in humans and rodents. Its deficiency suppressed cholesterol efflux, promoted foam cell formation, and exacerbated plaque features (macrophage infiltration, lipid deposition, necrotic cores) in macrophage-specific knockout mice. Conversely, Listerin overexpression attenuated these atherosclerotic manifestations. Mechanistically, Listerin stabilizes ABCA1, a key cholesterol efflux mediator, by catalyzing K63-linked polyubiquitination at residues K1884/K1957, countering ESCRT-mediated lysosomal degradation of ABCA1 induced by oxLDL. ABCA1 agonist Erythrodiol restored cholesterol efflux in Listerin-deficient macrophages, while ABCA1 knockout abolished Listerin's effects in THP-1 cells. This study establishes Listerin as a protective factor in atherosclerosis via post-translational stabilization of ABCA1, offering a potential therapeutic strategy targeting ABCA1 ubiquitination to enhance cholesterol efflux.

Authors

Lei Cao, Jie Zhang, Liwen Yu, Wei Yang, Wenqian Qi, Ruiqing Ren, Yapeng Liu, Yonghao Hou, Yu Cao, Qian Li, Xiaohong Wang, Zhengguo zhang, Bo Li, Wenhai Sui, Yun Zhang, Chengjiang Gao, Cheng Zhang, Meng Zhang

×

Abstract

Late-onset Tay-Sachs (LOTS) disease is a lysosomal storage disorder most commonly caused by a point mutation (c.805G>A) in the HEXA gene encoding the α-subunit of the lysosomal enzyme β-hexosaminidase A. LOTS manifests as a range of gradually worsening neurological symptoms beginning in young adulthood. Here, we explored the efficacy of an adenine base editor (ABE) programmed with a small guide RNA (sgRNA) to correct the HEXA c.805G>A mutation. Base editing in LOTS patient fibroblasts successfully converted the pathogenic HEXA c.805A to G and partially restored β-hexosaminidase activity, with minimal genome-wide off-target editing. We generated a LOTS mouse model in which the mice exhibited decreased β-hexosaminidase activity, accumulation of GM2 ganglioside in the brain, progressive neurological manifestations, and reduced lifespan. Treatment of LOTS mice with the neurotropic virus AAV-PHP.eB carrying the ABE and an sgRNA targeting the LOTS point mutation partially corrected the c.805G>A mutation in the CNS, significantly increased brain β-hexosaminidase activity, and substantially reduced GM2 ganglioside accumulation in the brain. Moreover, the therapy delayed symptom onset and significantly extended median lifespan. These findings highlight the potential of base editing as an effective treatment for LOTS and its broader applicability to other lysosomal storage disorders.

Authors

Maria L Allende, Mari Kono, Y. Terry Lee, Samantha M. Olmsted, Vienna Huso, Jenna Y. Bakir, Florencia Pratto, Cuiling Li, Colleen Byrnes, Galina Tuymetova, Hongling Zhu, Cynthia J. Tifft, Richard L. Proia

×

Abstract

The incretin peptides glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors coordinate β-cell secretion that is proportional to nutrient intake. This effect permits consistent and restricted glucose excursions across a range of carbohydrate intake. The canonical signaling downstream of ligand-activated incretin receptors involves coupling to Gɑs protein and generation of intracellular cyclic adenosine monophosphate (cAMP). However, recent reports have highlighted the importance of additional signaling nodes engaged by incretin receptors, including other G-proteins and β-arrestin proteins. Here, the importance of Gɑs signaling was tested in mice with conditional, post-developmental β-cell deletion of Gnas (encoding Gɑs) under physiological and pharmacological conditions. Deletion of Gɑs/cAMP signaling induced immediate and profound hyperglycemia that responded minimally to incretin receptor agonists, a sulfonylurea, or bethanechol. While islet area and insulin content were not affected in Gnasβcell-/-, perifusion of isolated islets demonstrated impaired responses to glucose, incretins, acetylcholine and IBMX. In the absence of Gɑs, incretin-stimulated insulin secretion was impaired but not absent, with some contribution from Gɑq signaling. Collectively, these findings validate a central role for cAMP to mediate incretin signaling, but also demonstrate broad impairment of insulin secretion in the absence of Gɑs that causes both fasting hyperglycemia and glucose intolerance.

Authors

Megan E. Capozzi, David Bouslov, Ashot Sargsyan, Michelle Y. Chan, Sarah M. Gray, Katrina Viloria, Akshay Bareja, Jonathan D. Douros, Sophie L. Lewandowski, Jason C.L. Tong, Annie Hasib, Federica Cuozzo, Elizabeth C. Ross, Matthew W. Foster, Lee S. Weinstein, Mehboob A. Hussain, Matthew J. Merrins, Francis S. Willard, Mark O. Huising, Kyle W. Sloop, David J. Hodson, David A. D'Alessio, Jonathan E. Campbell

×

Abstract

The mechanism of neutrophilic and mixed neutrophilic-eosinophilic asthma is poorly understood. We found that extracellular DNA and nucleosomes (Nuc) were elevated in the airways from neutrophilic-eosinophilic asthma patients and correlated with bronchoalveolar lavage neutrophils. Bronchial tissue from neutrophilic-eosinophilic asthma expressed increased DNA sensor-positive cells. Intranasally administered DNA did not induce airway hyperreactivity (AHR) or any pathology but induced AHR and neutrophilic-eosinophilic inflammation when co- administered with the allergen Alternaria (Alt). Nuc alone induced anti-inflammatory/defensive genes whereas the Nuc-Alt combo increased TNF and innate cytokines. The Alt-Nuc phenotype was abolished in Cgas-/-, ALR-/-, Sting-/-, LysMCre:Stingf/f, IL7RCre:Rorαf/f and Tnfr2-/- mice. Alt, unexpectedly, played an essential role in the Nuc-induced phenotype. It abrogated Nuc-induction of anti-inflammatory genes, facilitated Nuc uptake, induced ILC2s, which, in presence of Nuc, produced high levels of TNFα and promoted neutrophilic infiltration. We established a paradigm where allergens inhibit the anti-inflammatory effects of DNA/Nuc and facilitate STING-TNFα-driven neutrophilic-eosinophilic inflammation in asthma.

Authors

Anand Sripada, Divya Verma, Rangati Varma, Kapil Sirohi, Carolyn Kwiat, Mohini Pathria, Mukesh Verma, Anita Sahu, Vamsi P. Guntur, Laurie A. Manka, Brian Vestal, Camille M. Moore, Richard J. Martin, Magdalena M. Gorska, John Cambier, Andrew Getahun, Rafeul Alam

×

Advertisement

Review Series - More

Complement Biology and Therapeutics

Series edited by Claudia Kemper

The complement system executes an evolutionarily ancient innate immune response with important roles in many human diseases, including a variety of conditions involving the kidney, autoimmune disorders, age-related macular degeneration, and more. This series of reviews, curated by Dr. Claudia Kemper, highlights the latest discoveries in complement biology and examines ongoing efforts to target complement therapeutically. From the relatively newly uncovered functions of intracellular complement (complosome) to the complexities involved in using animal models of complementopathies, these reviews convey the challenges of studying complement and developing complement-targeted therapeutics as well as call attention to recent findings that supply momentum to the field.

×