Publications by authors named "Anh Leith"

5 Publications

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Drug Repurposing: The Anthelmintics Niclosamide and Nitazoxanide Are Potent TMEM16A Antagonists That Fully Bronchodilate Airways.

Front Pharmacol 2019 14;10:51. Epub 2019 Feb 14.

Department of Inflammation Research, Amgen Inc., Thousand Oaks, CA, United States.

There is an unmet need in severe asthma where approximately 40% of patients exhibit poor β-agonist responsiveness, suffer daily symptoms and show frequent exacerbations. Antagonists of the Ca-activated Cl channel, TMEM16A, offers a new mechanism to bronchodilate airways and block the multiple contractiles operating in severe disease. To identify TMEM16A antagonists we screened a library of ∼580,000 compounds. The anthelmintics niclosamide, nitazoxanide, and related compounds were identified as potent TMEM16A antagonists that blocked airway smooth muscle depolarization and contraction. To evaluate whether TMEM16A antagonists resist use- and inflammatory-desensitization pathways limiting β-agonist action, we tested their efficacy under harsh conditions using maximally contracted airways or airways pretreated with a cytokine cocktail. Stunningly, TMEM16A antagonists fully bronchodilated airways, while the β-agonist isoproterenol showed only partial effects. Thus, antagonists of TMEM16A and repositioning of niclosamide and nitazoxanide represent an important additional treatment for patients with severe asthma and COPD that is poorly controlled with existing therapies. It is of note that drug repurposing has also attracted wide interest in niclosamide and nitazoxanide as a new treatment for cancer and infectious disease. For the first time we identify TMEM16A as a molecular target for these drugs and thus provide fresh insights into their mechanism for the treatment of these disorders in addition to respiratory disease.
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http://dx.doi.org/10.3389/fphar.2019.00051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6382696PMC
February 2019

A Genome-wide Framework for Mapping Gene Regulation via Cellular Genetic Screens.

Cell 2019 01 3;176(1-2):377-390.e19. Epub 2019 Jan 3.

Department of Genome Sciences, University of Washington, Seattle, WA 98105, USA; Brotman Baty Institute for Precision Medicine, University of Washington, Seattle, WA 98105, USA; Howard Hughes Medical Institute, Seattle, WA 98105, USA. Electronic address:

Over one million candidate regulatory elements have been identified across the human genome, but nearly all are unvalidated and their target genes uncertain. Approaches based on human genetics are limited in scope to common variants and in resolution by linkage disequilibrium. We present a multiplex, expression quantitative trait locus (eQTL)-inspired framework for mapping enhancer-gene pairs by introducing random combinations of CRISPR/Cas9-mediated perturbations to each of many cells, followed by single-cell RNA sequencing (RNA-seq). Across two experiments, we used dCas9-KRAB to perturb 5,920 candidate enhancers with no strong a priori hypothesis as to their target gene(s), measuring effects by profiling 254,974 single-cell transcriptomes. We identified 664 (470 high-confidence) cis enhancer-gene pairs, which were enriched for specific transcription factors, non-housekeeping status, and genomic and 3D conformational proximity to their target genes. This framework will facilitate the large-scale mapping of enhancer-gene regulatory interactions, a critical yet largely uncharted component of the cis-regulatory landscape of the human genome.
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http://dx.doi.org/10.1016/j.cell.2018.11.029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6690346PMC
January 2019

Accurate classification of BRCA1 variants with saturation genome editing.

Nature 2018 10 12;562(7726):217-222. Epub 2018 Sep 12.

Department of Genome Sciences, University of Washington, Seattle, WA, USA.

Variants of uncertain significance fundamentally limit the clinical utility of genetic information. The challenge they pose is epitomized by BRCA1, a tumour suppressor gene in which germline loss-of-function variants predispose women to breast and ovarian cancer. Although BRCA1 has been sequenced in millions of women, the risk associated with most newly observed variants cannot be definitively assigned. Here we use saturation genome editing to assay 96.5% of all possible single-nucleotide variants (SNVs) in 13 exons that encode functionally critical domains of BRCA1. Functional effects for nearly 4,000 SNVs are bimodally distributed and almost perfectly concordant with established assessments of pathogenicity. Over 400 non-functional missense SNVs are identified, as well as around 300 SNVs that disrupt expression. We predict that these results will be immediately useful for the clinical interpretation of BRCA1 variants, and that this approach can be extended to overcome the challenge of variants of uncertain significance in additional clinically actionable genes.
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http://dx.doi.org/10.1038/s41586-018-0461-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6181777PMC
October 2018

IL-17RA Signaling in Airway Inflammation and Bronchial Hyperreactivity in Allergic Asthma.

Am J Respir Cell Mol Biol 2015 Dec;53(6):810-21

1 Inflammation Research, and.

Asthma is a heterogeneous disease characterized by airway inflammation and hyperreactivity. IL-17 receptor A (IL-17RA) is a shared receptor subunit required for activity of IL-17 family cytokines, including IL-17A and IL-25. IL-17A and IL-25 induce different proinflammatory responses, and concentrations are elevated in subjects with asthma. However, the individual contributions of IL-17A and IL-25 to disease pathogenesis are unclear. We explored proinflammatory activities of the IL-17 pathway in models of pulmonary inflammation and assessed its effects on contractility of human bronchial airway smooth muscle. In two mouse models, IL-17RA, IL-17RB, or IL-25 blockade reduced airway inflammation and airway hyperreactivity. Individually, IL-17A and IL-25 enhanced contractility of human bronchial smooth muscle induced by methacholine or carbachol. IL-17A had more pronounced effects on methacholine-induced contractility in bronchial rings from donors with asthma compared with donors without asthma. Blocking the IL-17 pathway via IL-17RA may be a useful therapy for some patients with asthma by reducing pulmonary inflammation and airway hyperreactivity.
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http://dx.doi.org/10.1165/rcmb.2015-0038OCDOI Listing
December 2015