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Abstract
Authors
Allen Duong, Sajad Moshkelgosha, Tereza Martinu, Stephen Juvet
Abstract
The pathogenesis of Bartter syndrome (BS) has long been attributed to decreased salt reabsorption in the thick ascending limb of Henle’s loop (TAL). By studying Clc-k2 (mouse ortholog of ClC-Kb)-knockout (Clc-k2-/-) mice, we recently uncovered an additional mechanism in which loss of Clc-k2 induces TAL hypoplasia in neonatal kidneys, exacerbating BS severity. Here, we further investigated this mechanism. TALs and distal convoluted tubules (DCTs) isolated from Clc-k2-/- and wild-type mice were used for transcriptome, proteomics, cell cycle, and proliferation assays. Mitochondrial morphology and function were studied using electron microscopy and mitochondrial respiration assays. Our results revealed impairments in cell proliferation, S-to-G2/M cell cycle transition, mitochondrial biogenesis, oxidative phosphorylation, glycolysis, and fatty acid oxidation in Clc-k2-/- TALs and DCTs. Increasing transport function by introducing a gain-of-function with-no-lysine kinase 4 mutation in Clc-k2-/- mice restored these metabolic and proliferative impairments and improved phenotype. Transgenic expression of peroxisome proliferator-activated receptor gamma coactivator-1α, a master regulator of mitochondrial biogenesis, in Clc-k2-/- mice also alleviated mitochondrial dysfunction and phenotype. These findings support the hypothesis that mitochondrial hypofunction, resulting from decreased transport function, contributes to cell cycle arrest and tubular hypoplasia in BS. Targeting mitochondria early in life could be a potential therapeutic approach for BS.
Authors
Chiao-Hui Hsieh, Yu-Jen Chen, Chih-Chien Sung, Emily Morrison, Chou-Long Huang, Chih-Jen Cheng
Abstract
Mycobacteriumtuberculosis (Mtb), the causative agent of tuberculosis (TB), is the most common coinfection in people living with HIV-1 (PLWH). This coinfection is associated with accelerated HIV-1 disease progression and reduced survival. However, the immunological and virological mechanisms driving this progression are not completely understood. To address this knowledge gap, using pleural effusion samples from PLWH and TB, we investigated how the HIV-1 genetic landscape and the anti-HIV-1 immune response are impacted by a TB-associated microenvironment. Our results revealed an enrichment of genetically intact HIV-1 and impaired CD8+ T cell-mediated antiviral response at this site of HIV-1/Mtb coinfection. Moreover, efficient CD8+ T cell activation was inhibited by lipids present in the TB-associated pleural effusion. These findings indicate that this immune microenvironment induced by TB promotes the persistence of cells infected with replication-competent HIV-1 by creating a niche of reduced antiviral immune pressure, potentially contributing to the worsened clinical outcomes observed in PLWH and TB.
Authors
Samantha Cronin, Jennifer Simpson, Andrea Pereyra-Casanova, Yuchen Li, Josefina Marín-Rojas, Freja A. Warner van Dijk, Katie Fisher, Daniel J. Buffa, Hafsa Rana, Zoï Vahlas, Joaquina Barros, Mariano Maio, Thomas R. O'Neil, Kirstie M. Bertram, Eunok Lee, Najla Nasr, Andrew N. Harman, Gabriela Turk, Maria Florencia Quiroga, Anthony D. Kelleher, Christel Vérollet, Luciana Balboa, Sarah Palmer, Gabriel Duette
Abstract
Skeletal muscle is composed of heterogeneous myofiber types and non-myocyte populations. Myopathies occur in many diseases, but mechanisms driving these pathologies remain largely unknown, partly because conventional approaches cannot link histopathological features to molecular states at single-fiber resolution. To address this challenge, we brought histopathology and spatial transcriptomics together by applying high-resolution Seq-Scope technology to a mouse model of mTORC1 hyperactivation. Cross-sections from extensor digitorum longus (EDL) and soleus (SOL), two muscles with distinct fiber-type compositions, were profiled to determine how transcriptome changes are linked to histopathological outcomes. mTORC1 hyperactivation elicited distinct, fiber-type-dependent pathological programs. Type I and IIa fibers were largely resistant to mTORC1-induced pathology, exhibiting relatively limited morphological alterations. In contrast, type IIx fibers diverged into opposing fates: in SOL, they underwent abnormal enlargement associated with sustained growth signaling, cytoskeletal remodeling, and impaired proteostasis; in EDL, they developed basophilia associated with increased RNA content and lipid, oxidative, and nucleotide metabolism-related signatures. Within EDL, type IIb fibers displayed heterogeneity with discrete transcriptional states. Non-myocytic populations, including macrophages and fibroblasts, accumulated preferentially in SOL, forming a fibrotic microenvironment associated with inflammation, remodeling, and hypertrophy. These findings provide a link between histopathological phenotypes and molecular states at single-fiber resolution.
Authors
Jer-En Hsu, Qingyang Zhao, Weiqiu Cheng, Hyun Min Kang, Susan V. Brooks, Myungjin Kim, Jun Hee Lee
Abstract
Plasmodium falciparum sporozoite (PfSPZ) vaccines, comprised of aseptic, purified, live parasites that arrest during or just after liver stage development, show excellent safety and efficacy in humans. They can induce complete protection against Pf infection, mediated primarily by cellular immune responses against parasite antigens expressed in hepatocytes. Current PfSPZ vaccines rely on the West African PfNF54 parasite, which uniquely produces high numbers of PfSPZ in mosquitoes, facilitating manufacturing efficiency. However, PfNF54 has relatively low hepatocyte infectivity, limiting potency. We created hybrid pan-African Pf strains by genetically crossing PfNF54 with East African Pf strains. The hybrid, AV27, was selected for development based on balanced contribution of parental genomes, high PfSPZ production and high liver stage infectivity. As compared to NF54-based PfSPZ vaccines, we expect AV27-based vaccines will have greater and broader efficacy at lower doses due to higher liver stage infectivity and inclusion of unique East African CD8+ T cell epitopes.
Authors
Lucia Pazzagli, Bethany Jenkins, Ankit Dwivedi, Asha Patil, Yonas Abebe, Tales V. Pascini, Urvashi Rai, Priya Gupta, Nastaran Rezakhani, Chakshu Gandhi, Yiwei Yang, Sudhir Kumar, Mohd Kamil, Gigliola Zanghí, Manuel Llinás, Stephen L. Hoffman, Joana C. Silva, Ashley M. Vaughan, B. Kim Lee Sim
Abstract
Systemic lupus erythematosus (SLE) is a progressive autoimmune disease that affects multiple organs and tissues, with lupus nephritis (LN) as one of its most severe complications. While LN progression is associated with compromised permeability of human renal glomerular endothelial cells (HRGECs), the underlying mechanisms are not fully defined. Herein, we demonstrate that aberrant glycolysis drives this glomerular endothelial barrier defect by suppressing the transcription of tight junction (TJ) genes. Mechanistically, circulating self-DNA in SLE plasma acts as a ligand that activates the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway in HRGECs, driving aberrant glycolytic adaption. The resulting glycolytic product, lactate, serves as a substrate for protein lactylation, leading to extensive lactylation and subsequent ubiquitination of the enhancer of zeste homolog 2 (EZH2). In consequence, EZH2 deficiency results in reduced H3K27me3 levels, thereby suppressing the transcription of TJ genes. In a self-DNA-induced SLE model, inhibition of cGAS-STING signaling or lactate production effectively restored the integrity of TJs of HRGECs and concurrently alleviated key LN symptoms. Together, lactate programs lactylation and ubiquitination of EZH2 to impair glomerular endothelial barrier in human SLE.
Authors
Jiaxin Lei, Xingyu Zhai, Yixin Wang, Ying Li, Lei Li, Mengdi Liu, Jing Guo, Lingyi Li, Zhezhuyun Chen, Qinghua Cao, Zhichun Liu, Ting Liu, Lin Xu, Zhenke Wen
Abstract
Authors
Kadambari Vijaykumar, Liang Ma, Kevin Chen, Liping Tang, Nikoleta Pavelkova, Elex Harris, Kajal Jadhav, Qian Li, Mohamed Hanafy, Hinnerk Schulz-Hildebrandt, Guillermo J. Tearney, Finn Hawkins, Darrell N. Kotton, Steven M. Rowe
Abstract
Chronic kidney disease is a global health concern characterized by maladaptive repair processes leading to kidney fibrosis. Following injury, early alterations in the extracellular matrix precede the development of kidney fibrosis and represent potential therapeutic targets to improve kidney repair. In this context, studies from our laboratory and others have shown that the matricellular protein SMOC2 can be targeted to decrease inflammation and tubulointerstitial fibrosis following kidney injury. The tubular epithelial cells (TECs), which are abundant and particularly susceptible to injury, play a central role in maladaptive repair; however, whether SMOC2 affects their functionality after kidney injury has not been explored. In this study, we show that SMOC2 localizes to the basement membrane of injured TECs across three murine models of kidney injury. Our in vitro studies demonstrate that SMOC2 induces a partial epithelial-to-mesenchymal (EMT) transition of TECs. We further demonstrate that its extracellular calcium-binding domain mediates binding to the decellularized extracellular matrix and mediates most of its effects on TECs. Mechanistically, SMOC2 promotes partial EMT effects through an integrin-dependent pathway. Together, these findings provide new mechanistic insight into how SMOC2 drives maladaptive repair by modulating TEC behavior and identify its calcium-binding domain as a key functional mediator.
Authors
Schrodinger Cenatus, Peng Gao, Nathalie Henley, Caroline Lamarche, Xue-Song Liu, Frédérick A. Mallette, Jonatan Barrera-Chimal, Casimiro Gerarduzzi
Abstract
The glymphatic-meningeal pathway, important for brain homeostasis, depends on the drainage function of the cervical lymphatic system. Although new therapies aim to modulate this pathway, a lack of methods for quantifying lymphatic drainage function hinders our ability to understand how targeting the cervical lymph nodes may benefit brain health. To address this, we developed and applied a fluid transport model to dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data to visualize and quantify tracer-tagged lymph through the deep cervical lymph nodes (dcLN). The model incorporated physical principles of solute transport to provide a biologically interpretable framework for analyzing microflows in real-time. We applied this model to investigate the effects of chronic hypertension on dcLN drainage by comparing normotensive Wistar-Kyoto rats with spontaneously hypertensive stroke-prone (SHRSP) rats. In normal rats, the model revealed complex and tortuous lymph streams, of a 200 kDa tracer transported through the sinus system of the dcLN. In contrast, SHRSP rats exhibited significantly altered fluid dynamics, characterized by simpler stream patterns and reduced flow through the dcLN. These findings demonstrated that untreated chronic hypertension adversely affects lymph node drainage function. This provides new insight into impaired lymphatic drainage as a mechanism linking systemic disease to brain health.
Authors
Kaiming Xu, Ankita Bhardwaj, Sunil Koundal, Qin Ren, Chenyu You, Xenophon Papademetris, Helene Benveniste, Tryphon T. Georgiou
Abstract
Bone marrow-derived circulating monocytes continuously replenish intestinal macrophages, which become dysregulated in inflammatory bowel disease (IBD) and contribute to disease pathology. The origins of this dysregulation remain poorly understood. Here, we investigate the reprogramming of circulating monocytes in IBD prior to tissue recruitment using single-cell transcriptomic, epigenomic and functional approaches. We characterise blood monocyte heterogeneity in newly diagnosed, treatment-naïve IBD patients and healthy controls and show that monocytes in Crohn’s disease (CD) display a distinct transcriptional profile and altered distributions across inferred developmental trajectories; less pronounced changes are observed in ulcerative colitis (UC). We link CD-associated transcriptional changes to alterations in chromatin accessibility and identify NFB, EGR, KLF and AP-1 family transcription factors as putative regulators of an inflammatory gene program in blood monocytes from CD patients. We uncover a potential role for IFN- in priming blood monocytes for inflammatory function in CD by limiting their capacity to be regulated by IL-10. Finally, we show that the transcriptional and functional alterations in monocytes from CD patients are maintained in monocyte-derived cells from the intestine. Together these data suggest that intestinal macrophage dysfunction in CD is, at least in part, pre-established by systemic signals prior to tissue recruitment.
Authors
Eve Hornsby, Radha Gadhok, Inva Hoti, Eva Wozniak, James R. Boot, Emma Connick, Paul A Stevens, Holly Creed, Amy Lewis, Andrew Silver, James O Lindsay, Andrew J. Stagg
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