In this issue, Khan et al. report a comprehensive analysis of antibody responses in children and adults to the four endemic human coronaviruses. Antibody repertoires differed between children and adults, with children more frequently having antibodies that target functionally important and structurally conserved regions of the spike, nucleocapsid, and matrix proteins. Moreover, they found antibodies targeting a highly conserved region of the spike protein that were cross-reactive among multiple coronaviruses, suggesting a potential important target for vaccine design. The cover image is an illustration of antibodies and a coronavirus. Image credit: Tatiana Shepeleva/Shutterstock.
ORM1-like 3 (ORMDL3) has strong genetic linkage to childhood onset asthma. To determine whether ORMDL3 selective expression in airway smooth muscle (ASM) influences ASM function we used cre/lox techniques to generate transgenic mice (hORMDL3Myh11eGFP-cre) which express human ORMDL3 selectively in smooth muscle cells. In vitro studies of ASM cells isolated from the bronchi of hORMDL3Myh11eGFP-cre mice demonstrated that they developed hypertrophy (quantitated by FACS and image analysis), hyperplasia (assessed by BrdU incorporation), and expressed increased levels of tropomysin proteins TPM1 and TPM4. siRNA knockdown of TPM1 or TPM4 demonstrated their importance to ORMDL3 mediated ASM proliferation but not hypertrophy. In addition, ASM derived from hORMDL3Myh11eGFP-cre mice had increased contractility to histamine in vitro which was associated with increased levels of intracellular Ca2+, increased cell surface membrane Orai1 Ca2+ channels which mediate influx of Ca2+ into the cytoplasm, and increased expression of ASM contractile genes Serca2b and Sm22. In vivo studies of hORMDL3Myh11eGFP-cre mice demonstrated that they had a spontaneous increase in ASM and AHR. ORMDL3 expression in ASM thus induces changes in ASM (hypertrophy, hyperplasia, increased contractility) which may explain the contribution of ORMDL3 to the development of AHR in childhood onset asthma which is highly linked to ORMDL3 on chromosome 17q12-21.
Alexa K. Pham, Marina Miller, Peter Rosenthal, Sudipta Das, Ning Weng, Sunghoon Jang, Richard C. Kurten, Jana Badrani, Taylor A. Doherty, Brian G. Oliver, David H. Broide
During denervation induced muscle atrophy, the loss of neuro-muscular junction (NMJ) integrity and the consequent cessation of nerve signal transmission to muscle, lead to a decline in myofiber size mass and contractile activity. However, the identity of the cell types implicated in the muscle response to nerve injury has not been clearly defined. Here, we describe a subpopulation of muscle resident glial cells activated by loss of NMJ integrity. Gene expression analysis at bulk and single cell level revealed the existence of a population of Itga7-expressing cells, which are distinct from muscle satellite cells and are selectively activated upon nerve injury. Upon nerve lesion, these cells expanded and activated a neurotrophic gene program, including the expression of a prospective selection marker – Ngfr – and a number of neurotrophic genes as well as ECM components. Among them, we observed that Tenascin C (Tnc) was specifically produced by muscle glial cells activated by nerve injury and preferentially localized to NMJ. Activation of muscle-resident glial cells by nerve injury induced a neurotrophic phenotype, which was reversible upon recovery of NMJ integrity; by contrast, muscle-resident glial cells in skeletal muscles of a mouse model of Amyotrophic Lateral Sclerosis (ALS) steadily increased over the course of the disease and exhibited an impaired neurotrophic activity, suggesting that pathogenic activation of glial cells may be implicated in ALS progression.
Daisy Proietti, Lorenzo Giordani, Marco De Bardi, Chiara D'Ercole, Biliana Lozanoska-Ochser, Susanna Amadio, Cinzia Volontè, Sara Marinelli, Antoine Muchir, Marina Bouchè, Giovanna Borsellino, Alessandra Sacco, Pier Lorenzo Puri, Luca Madaro
Secretory protein misfolding has been linked to ER stress and cell death. We expressed a TGrdw transgene encoding TG-G(2298)R, a misfolded mutant thyroglobulin reported to be linked to thyroid cell death. When the TGrdw transgene was expressed at low-level in thyrocytes of TGcog/cog mice that experience severe ER stress, we observed increased thyrocyte cell death and increased expression of CIDE-A (Cell death-inducing DFFA-like effector-A, a protein of lipid droplets) in whole thyroid gland. Here we demonstrate that acute ER stress in cultured PCCL3 thyrocytes increases Cidea mRNA levels, maintained at least in part by increased mRNA stability, while being negatively regulated by ATF6 — with similar observations other cell types. CIDE-A protein is sensitive to proteasomal degradation yet is stabilized by ER stress, and elevated expression levels accompany increased cell death. Unlike acute ER stress, PCCL3 cells adapted and surviving chronic ER stress maintain a disproportionately lower relative mRNA level of Cidea compared to that of other, classical ER stress markers, as well as a blunted Cidea mRNA response to a new, unrelated acute ER stress challenge. We suggest that CIDE-A is a novel marker linked to a non-canonical ER stress-response program, with implications for cell death and survival.
Yoshiaki Morishita, Aaron P. Kellogg, Dennis Larkin, Wei Chen, Suryakiran Vadrevu, Leslie S. Satin, Ming Liu, Peter Arvan
Introduction: Coronavirus 2019 (COVID-19) clinical course is heterogeneous, ranging from mild to severe multi-organ failure and death. In this study, we analyzed cell-free DNA (cfDNA) as a biomarker of injury to define the sources of tissue injury that contribute to such different trajectories. Methods: We conducted a multi-center prospective cohort study to enroll COVID-19 patients and collect plasma samples. Plasma cfDNA was subject to bisulfite sequencing. A library of tissue-specific DNA methylation signatures was used to analyze sequence reads to quantitate cfDNA from different tissue types. We then determined the correlation of tissue-specific cfDNA measures to COVID-19 outcomes. Similar analyses was performed for healthy controls and a comparator group of patients with respiratory syncytial virus and influenza. Results: We found markedly elevated levels and divergent tissue sources of cfDNA in COVID-19 patients compared to influenza and respiratory syncytial virus patients or healthy controls. The major sources of cfDNA in COVID-19 were hematopoietic cells, vascular endothelium, hepatocyte, adipocyte, kidney, heart and lung. cfDNA levels positively correlated with COVID-19 disease severity, c reactive protein, D-Dimer. cfDNA profile at admission identified patients who subsequently required intensive care or died during hospitalization. Furthermore, the increased cfDNA in COVID-19 patients generates excessive mitochondrial reactive oxygen species (mtROS) in renal tubular cells in a concentration-dependent manner. This mtROS production was inhibited by a toll-like receptor 9 (TLR-9)-specific antagonist. Conclusion cfDNA maps tissue injury that predict COVID-19 outcomes, and may mechanistically propagates COVID-19 induced tissue injury. Funding sources: Intramural Targeted Anti-COVID-19 grant, National Institutes of Health
Temesgen E. Andargie, Naoko Tsuji, Fayaz Seifuddin, Moon Kyoo Jang, Peter S.T. Yuen, Hyesik Kong, Ilker Tunc, Komudi Singh, Ananth Charya, Kenneth J. Wilkins, Steven D. Nathan, Andrea L. Cox, Mehdi Pirooznia, Robert A. Star, Sean Agbor-Enoh
Gene replacement for Duchenne muscular dystrophy (DMD) with micro-dystrophins has entered clinical trials, but efficacy on preventing heart failure is unknown. Although most DMD patients die from heart failure, cardiomyopathy is undetectable until the teens so efficacy from trials in young boys will be unknown for a decade. Available DMD animal models were sufficient to demonstrate micro-dystrophin efficacy on earlier onset skeletal muscle pathology underlying loss of ambulation and respiratory insufficiency in patients. However, no mouse models progressed into heart failure and dog models show highly variable progression insufficient to evaluate efficacy of micro-dystrophin or other therapies on DMD heart failure. To overcome this barrier, we have generated the first DMD mouse model that reproducibly progresses into heart failure. This model shows cardiac inflammation and fibrosis occur prior to reduced function. Fibrosis does not continue to accumulate, but inflammation persists after function declines. We used this model to test micro-dystrophin gene therapy efficacy on heart failure prevention for the first time. Micro-dystrophin prevents declines in cardiac function and prohibits onset of inflammation and fibrosis. This model will allow identification of committed pathogenic steps to heart failure and testing of genetic and non-genetic therapies to optimize cardiac care for DMD patients.
Zachary M. Howard, Lisa E. Dorn, Jeovanna Lowe, Megan D. Gertzen, Pierce C. Ciccone, Neha Rastogi, Guy L. Odom, Federica Accornero, Jeffrey S. Chamberlain, Jill A. Rafael-Fortney
JCI This Month is a digest of the research, reviews, and other features published each month.