Research
Abstract
Repetitive mild traumatic brain injuries (mTBI) disrupt central nervous system (CNS) barriers, the erosion of which has been linked to long-term neurodegenerative and psychiatric conditions. Although much attention has been devoted to CNS vasculature following mTBI, little is known about the glia limitans superficialis - a barrier of surface-associated astrocytes that helps protect the CNS parenchyma and maintain homeostasis. Here, we identify the glia limitans superficialis as a crucial barrier surface whose breakdown after acute repeat mTBI facilitates increased cell death and recruitment of peripheral myelomonocytic cells. Using intravital microscopy, we show that brain resident microglia fortify this structure after a single mTBI yet fail to do so following secondary injury, which triggers massive recruitment of myelomonocytic cells from the periphery that contribute to further destruction of the glia limitans superficialis but not cortical cell death. We demonstrate instead that reactive oxygen species (ROS) generated in response to repeat head injury are largely responsible for enhanced cortical cell death, and therapeutic administration of the antioxidant, glutathione, markedly reduces this cell death, preserves the glia limitans, and prevents myelomonocytic cells from entering the brain parenchyma. Collectively, our findings underscore the importance of preserving the glia limitans superficialis after brain injury and offer a therapeutic means to protect this structure and the underlying cortex.
Authors
Hannah D. Mason, Alexis M. Johnson, Nicole A. Mihelson, Panagiotis Mastorakos, Dorian B. McGavern
Abstract
IgA nephropathy is caused by deposition of circulatory IgA1 in the kidney. Hypo-galactosylated IgA1 has the propensity to form poly-IgA aggregates that are prone to deposition. We purified poly-IgA from the plasma of IgA nephrology patients and showed the complex being susceptible to reducing condition, suggesting intermolecular disulfide connections between IgA units. We sought to find the cysteine residue(s) in forming intermolecular disulfide. Naturally assembled dimeric IgA, also known as secretory IgA, involves a J-chain subunit connected with two IgA1 molecules via their penultimate cysteine-471 residue on ‘tailpiece’ segment of IgA heavy chain. It is plausible that, with the absence of J-chain, the cysteine residue of mono-IgA1 might aberrantly form disulfide bond in poly-IgA formation. Mutagenesis confirmed cysteine-471 capable of promoting IgA aggregation. These discoveries prompted us to test thiol-based drugs for stabilizing cysteine. Specifically, cystine-reducing drug cysteamine used for treatment of cystinosis showed a remarkable potency in preventing IgA from self-aggregation. When administrated to rat and mouse models of IgA nephropathy, cysteamine significantly reduced glomerular IgA deposition. Collectively, our results revealed a novel molecular mechanism for aberrant formation of IgA aggregates, to which repurposed cystinosis drug cysteamine was efficacious in preventing renal IgA deposition.
Authors
Xinfang Xie, Li Gao, Pan Liu, Jicheng Lv, Wan-Hong Lu, Hong Zhang, Jing Jin
Abstract
The prevalence of hypertension is increasing globally, while strategies for prevention and treatment of hypertension remain limited. FG-4592 (Roxadustat) is a novel, orally active small-molecule HIF stabilizer, and is being used clinically to treat CKD anemia. In the present study, we evaluate the effects of FG-4592 on hypertension. In an Ang II hypertension model, FG-4592 abolished hypertensive responses, prevented vascular thickening, cardiac hypertrophy, and kidney injury, downregulated AGTR1 expression, and enhanced AGTR2, eNOS, and HIF1α protein levels in the aortas of mice. Additionally, the levels of thiobarbituric acid reactive substances (TBARs) in blood and urine were diminished by FG-4592 treatment. In vascular smooth muscle cells, FG-4592 treatment reduced AGTR1 and increased AGTR2 levels, while preventing Ang II-induced oxidative stress. In vascular endothelial cells, FG-4592 upregulated total and phosphorylated eNOS. Moreover, FG-4592 treatment was hypotensive in L-NAME-induced hypertension. In summary, FG-4592 treatment remarkably ameliorated hypertension and organ injury, possibly through stabilizing HIF1α and subsequently targeting eNOS, AGTR1, AGTR2, and oxidative stress. Therefore, in addition to its role in treating CKD anemia, FG-4592 could be explored as a treatment for hypertension associated with high RAS activity or eNOS defects.
Authors
Jing Yu, Shuqin Wang, Wei Shi, Wei Zhou, Yujia Niu, Songming Huang, Yue Zhang, Aihua Zhang, Zhanjun Jia
Abstract
MicroRNA-150 (miR-150) is downregulated in patients with multiple cardiovascular diseases and in diverse mouse models of heart failure (HF). MiR-150 is significantly associated with HF severity and outcome in humans. We previously reported that miR-150 is activated by β-blocker carvedilol (Carv) and plays a protective role in the heart using a systemic miR-150 knockout (KO) mouse model. However, mechanisms that regulate cell-specific miR-150 expression and function in HF are unknown. Here, we demonstrate that novel conditional cardiomyocyte (CM)-specific miR-150 knockout (miR-150 cKO) in mice worsens maladaptive cardiac remodeling after myocardial infarction (MI). Genome-wide transcriptomic analysis in miR-150 cKO mouse hearts identifies small proline-rich protein 1a (Sprr1a) as a novel target of miR-150. Our studies further reveal that Sprr1a expression is upregulated in CMs isolated from ischemic myocardium and subjected to simulated ischemia/reperfusion, while its expression is downregulated in hearts and CMs by Carv. We also show that left ventricular SPRR1A is upregulated in patients with HF and that Sprr1a knockdown in mice prevents maladaptive post-MI remodeling. Lastly, protective roles of CM miR-150 are in part attributed to the direct and functional repression of pro-apoptotic Sprr1a. Our findings suggest a crucial role for the miR-150/SPRR1A axis in regulating CM function post-MI.
Authors
Tatsuya Aonuma, Bruno Moukette, Satoshi Kawaguchi, Nipuni P. Barupala, Marisa N. Sepulveda, Christopher Corr, Yaoliang Tang, Suthat Liangpunsakul, R. Mark Payne, Monte S. Willis, Il-man Kim
Abstract
Neutrophils provide a critical line of defense in immune responses to various pathogens, but also inflict self-damage upon transition to a hyperactivated, procoagulant state. Recent work has highlighted proinflammatory neutrophil phenotypes contributing to lung injury and acute respiratory distress syndrome (ARDS) in patients suffering from COVID-19. Here, we utilize state-of-the art mass spectrometry-based proteomics, transcriptomic and correlative analyses as well as functional in vitro and in vivo studies to dissect how neutrophils contribute to the progression to severe COVID-19. We identify a reinforcing loop of both systemic and neutrophil intrinsic interleukin-8 (CXCL8/IL-8) dysregulation, which initiates and perpetuates neutrophil-driven immunopathology. This positive feedback loop of systemic and neutrophil autocrine IL-8 production leads to an activated, prothrombotic neutrophil phenotype characterized by degranulation and neutrophil extracellular trap (NET) formation. In severe COVID-19, neutrophils directly initiate the coagulation and complement cascade, highlighting a link to the immunothrombotic state observed in these patients. Targeting the IL-8-CXCR-1/-2 axis interferes with this vicious cycle and attenuates neutrophil activation, degranulation, NETosis, and IL-8 release. Finally, we show that blocking IL-8-like signaling reduces SARS-CoV-2 spike protein-induced, hACE2-dependent pulmonary microthrombosis in mice. In summary, our data provide comprehensive insights into the activation mechanisms of neutrophils in COVID-19 and uncover a self-sustaining neutrophil-IL-8-axis as promising therapeutic target in severe SARS-CoV-2 infection.
Authors
Rainer Kaiser, Alexander Leunig, Kami Pekayvaz, Oliver Popp, Markus Joppich, Vivien Polewka, Raphael Escaig, Afra Anjum, Marie-Louise Hoffknecht, Christoph Gold, Sophia Brambs, Anouk Engel, Sven Stockhausen, Viktoria Knottenberg, Anna Titova, Mohamed Haji, Clemens Scherer, Maximilian Muenchhoff, Johannes C. Hellmuth, Kathrin Saar, Benjamin Schubert, Anne Hilgendorff, Christian Schulz, Stefan Kääb, Ralf Zimmer, Norbert Hübner, Steffen Massberg, Philipp Mertins, Leo Nicolai, Konstantin Stark
Abstract
Autoimmune disease has presented an insurmountable barrier to restoration of durable immune tolerance. Previous studies indicate that chronic therapy with metabolic inhibitors can reduce autoimmune inflammation, but it remains unknown whether acute metabolic modulation enables permanent immune tolerance to be established. In an animal model of lupus, we determined that targeting glucose metabolism with 2-deoxyglucose (2DG) and mitochondrial metabolism with metformin enables endogenous immune tolerance mechanisms to respond to tolerance induction. A 2-week course of 2DG and metformin, when combined with tolerance-inducing therapy anti-CD45RB, prevented renal deposition of autoantibodies for 6 months after initial treatment and also restored tolerance induction to allografts in lupus-prone mice. The restoration of durable immune tolerance was linked to changes in T cell surface glycosylation patterns, illustrating a role for glycoregulation in immune tolerance. These findings indicate that metabolic therapy may be applied as a powerful preconditioning to reinvigorate tolerance mechanisms in autoimmune and transplant settings that resist current immune therapies.
Authors
Christopher S. Wilson, Blair T. Stocks, Emilee M. Hoopes, Jillian P. Rhoads, Kelsey L. McNew, Amy S. Major, Daniel J. Moore
Abstract
Venous valve (VV) failure causes chronic venous insufficiency, but the molecular regulation of valve development is poorly understood. A primary lymphatic anomaly, caused by mutations in the receptor tyrosine kinase EPHB4, was recently described, with these patients also presenting with venous insufficiency. Whether the venous anomalies are the result of an effect on VVs is not known. VV formation requires complex ‘organization’ of valve-forming endothelial cells, including their reorientation perpendicular to the direction of blood flow. Using quantitative ultrasound we identified substantial VV aplasia and deep venous reflux in patients with mutations in EPHB4. We used a GFP reporter, in mice, to study expression of its ligand, ephrinB2, and analysed developmental phenotypes following conditional deletion of floxed Ephb4 and Efnb2 alleles. EphB4 and ephrinB2 expression patterns were dynamically regulated around organizing valve-forming cells. Efnb2 deletion disrupted the normal endothelial expression patterns of the gap junction proteins connexin37 and connexin43 (both required for normal valve development) around reorientating valve-forming cells, and produced deficient valve-forming cell elongation, reorientation, polarity, and proliferation. Ephb4 was also required for valve-forming cell organization, and subsequent growth of the valve leaflets. These results uncover a potentially novel cause of primary human VV aplasia.
Authors
Oliver Lyons, James Walker, Christopher Seet, Mohammed Ikram, Adam Kuchta, Andrew Arnold, Magda Hernández-Vásquez, Maike Frye, Gema Vizcay-Barrena, Roland A. Fleck, Ashish S. Patel, Soundrie Padayachee, Peter Mortimer, Steve Jeffery, Siren Berland, Sahar Mansour, Pia Ostergaard, Taija Makinen, Bijan Modarai, Prakash Saha, Alberto Smith
Abstract
Glioblastoma is a highly malignant brain tumor with no curative treatment options, and immune checkpoint blockade has not yet shown major impact. We hypothesized that drugs targeting mitosis might impact the tumor microenvironment and sensitize cancer cells to immunotherapy. We used two glioblastoma mouse models with different immunogenicity profiles, GL261 and SB28, to test the efficacy of antineoplastic and immunotherapy combinations. The spindle assembly checkpoint activator BAL101553 (lisavanbulin), agonistic anti-CD40 antibody, and double immune checkpoint blockade (anti-PD-1 and anti-CTLA-4) were evaluated individually or in combination for treating orthotopic GL261 and SB28 tumors. Genomic and immunological analyses were used to predict and interpret therapy responsiveness. BAL101553 monotherapy increased survival in immune checkpoint blockade resistant SB28 glioblastoma tumors and synergized with anti-CD40 antibody, in a T-cell independent manner. In contrast, the more immunogenic and highly mutated GL261 model responded best to anti-PD-1 and anti-CTLA-4 therapy and more modestly to BAL101553 and anti-CD40 combination. Our results show that BAL101553 is a promising therapeutic agent for glioblastoma and could synergize with innate immune stimulation. Overall, these data strongly support immune profiling of glioblastoma patients and preclinical testing of combination therapies with appropriate models for particular patient groups.
Authors
Vassilis Genoud, Felipe I. Espinoza, Eliana Marinari, Viviane Rochemont, Pierre-Yves Dietrich, Paul McSheehy, Felix Bachmann, Heidi A. Lane, Paul R. Walker
Abstract
Kawasaki disease (KD) is the leading cause of acquired heart disease among children. Murine and human data suggest that the NLRP3-IL-1β pathway is the main driver of KD pathophysiology. NLRP3 can be activated during defective autophagy/mitophagy. We used the Lactobacillus casei cell wall extract (LCWE) murine model of KD vasculitis, to examine the role of autophagy/mitophagy on cardiovascular lesion development. LCWE-injected mice had impaired autophagy/mitophagy and increased levels of ROS in cardiovascular lesions, together with increased systemic 8-OHdG release. Enhanced autophagic flux significantly reduced cardiovascular lesions in LCWE-injected mice, whereas autophagy blockade increased inflammation. Vascular smooth muscle cell specific deletion of Atg16l1 and global Parkin-/- significantly increased disease formation, supporting the importance of autophagy/mitophagy in this model. Ogg1-/- mice had significantly increased lesions with increased NLRP3 activity, whereas treatment with MitoQ, reduced vascular tissue inflammation, ROS production and systemic 8-OHdG release. Treatment with MN58b or Metformin (increasing AMPK and reducing ROS), resulted in decreased disease formation. Our results demonstrate that impaired autophagy/mitophagy and ROS-dependent damage exacerbate the development of murine KD vasculitis. This pathway can be efficiently targeted to reduce disease severity. These findings enhance our understanding of KD pathogenesis and identify novel therapeutic avenues for KD treatment.
Authors
Stefanie Marek-Iannucci, A. Beyza Ozdemir, Debbie Moreira, Angela C. Gomez, Malcolm Lane, Rebecca A Porritt, Youngho Lee, Kenichi Shimada, Masanori Abe, Aleksandr Stotland, David Zemmour, Sarah Parker, Elsa Sanchez-Lopez, Jennifer Van Eyk, Roberta A. Gottlieb, Michael Fishbein, Michael Karin, Timothy R Crother, Magali Noval Rivas, Moshe Arditi
Abstract
Oligoarticular juvenile idiopathic arthritis (oligo JIA) is the most common form of chronic inflammatory arthritis in children; yet, the cause of this disease remains unknown. To understand immune responses in oligo JIA, we immunophenotyped synovial fluid T cells with flow cytometry, bulk and single-cell RNA sequencing, DNA methylation studies, and Treg suppression assays. In synovial fluid, CD4+, CD8+, and γδ T cells expressed Th1-related markers, while Th17 cells were not enriched. Th1 skewing was prominent in CD4+ T cells, including Tregs, and was associated with severe disease. Transcriptomic studies confirmed a Th1 signature in CD4+ T cells from synovial fluid. The regulatory gene expression signature was preserved in Tregs, even those exhibiting Th1 polarization. These Th1-like Tregs maintained Treg specific methylation patterns and suppressive function, supporting the stability of this Treg population in the joint. While synovial fluid CD4+ T cells displayed an overall Th1 phenotype, scRNA-seq uncovered heterogeneous effector and regulatory sub-populations, including interferon-induced Tregs, peripheral helper T cells, and cytotoxic CD4+ T cells. In conclusion, oligo JIA is characterized by Th1 polarization that encompasses Tregs but does not compromise their regulatory identity. Targeting Th1-driven inflammation and augmenting Treg function may represent important therapeutic approaches in oligo JIA.
Authors
Amélie M. Julé, Kacie J. Hoyt, Kevin Wei, Maria Gutierrez-Arcelus, Maria L. Taylor, Julie Ng, James A. Lederer, Siobhan M. Case, Margaret H. Chang, Ezra M. Cohen, Fatma Dedeoglu, Melissa M. Hazen, Jonathan S. Hausmann, Olha Halyabar, Erin Janssen, Jeffrey Lo, Mindy S. Lo, Esra Meidan, Jordan E. Roberts, Mary Beth F. Son, Robert P. Sundel, Pui Y. Lee, Talal Chatila, Peter A. Nigrovic, Lauren A. Henderson
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