Publications by authors named "Sunit Singla"

12 Publications

  • Page 1 of 1

Chronic E-Cigarette Aerosol Inhalation Alters the Immune State of the Lungs and Increases ACE2 Expression, Raising Concern for Altered Response and Susceptibility to SARS-CoV-2.

Front Physiol 2021 31;12:649604. Epub 2021 May 31.

Pulmonary Critical Care Section, VA San Diego Healthcare System, La Jolla, CA, United States.

Conventional smoking is known to both increase susceptibility to infection and drive inflammation within the lungs. Recently, smokers have been found to be at higher risk of developing severe forms of coronavirus disease 2019 (COVID-19). E-cigarette aerosol inhalation (vaping) has been associated with several inflammatory lung disorders, including the recent e-cigarette or vaping product use-associated lung injury (EVALI) epidemic, and recent studies have suggested that vaping alters host susceptibility to pathogens such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To assess the impact of vaping on lung inflammatory pathways, including the angiotensin-converting enzyme 2 (ACE2) receptor known to be involved in SARS-CoV-2 infection, mice were exposed to e-cigarette aerosols for 60 min daily for 1-6 months and underwent gene expression analysis. Hierarchical clustering revealed extensive gene expression changes occurred in the lungs of both inbred C57BL/6 mice and outbred CD1 mice, with 2,933 gene expression changes in C57BL/6 mice, and 2,818 gene expression changes in CD1 mice (>abs 1.25-fold change). Particularly, large reductions in IgA and CD4 were identified, indicating impairment of host responses to pathogens reductions in immunoglobulins and CD4 T cells. CD177, facmr, tlr9, fcgr1, and ccr2 were also reduced, consistent with diminished host defenses decreased neutrophils and/or monocytes in the lungs. Gene set enrichment (GSE) plots demonstrated upregulation of gene expression related to cell activation specifically in neutrophils. As neutrophils are a potential driver of acute lung injury in COVID-19, increased neutrophil activation in the lungs suggests that vapers are at higher risk of developing more severe forms of COVID-19. The receptor through which SARS-CoV-2 infects host cells, ACE2, was found to have moderate upregulation in mice exposed to unflavored vape pens, and further upregulation (six-fold) with JUUL mint aerosol exposure. No changes were found in mice exposed to unflavored Mod device-generated aerosols. These findings suggest that specific vaping devices and components of e-liquids have an effect on ACE2 expression, thus potentially increasing susceptibility to SARS-CoV-2. In addition, exposure to e-cigarette aerosols both with and without nicotine led to alterations in eicosanoid lipid profiles within the BAL. These data demonstrate that chronic, daily inhalation of e-cigarette aerosols fundamentally alters the inflammatory and immune state of the lungs. Thus, e-cigarette vapers may be at higher risk of developing infections and inflammatory disorders of the lungs.
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http://dx.doi.org/10.3389/fphys.2021.649604DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8194307PMC
May 2021

Cigarette Smoke and Nicotine-Containing Electronic-Cigarette Vapor Downregulate Lung WWOX Expression, Which Is Associated with Increased Severity of Murine Acute Respiratory Distress Syndrome.

Am J Respir Cell Mol Biol 2021 01;64(1):89-99

Division of Pulmonary, Critical Care, Sleep and Allergy Medicine, University of Illinois, Chicago, Illinois.

A history of chronic cigarette smoking is known to increase risk for acute respiratory distress syndrome (ARDS), but the corresponding risks associated with chronic e-cigarette use are largely unknown. The chromosomal fragile site gene, WWOX, is highly susceptible to genotoxic stress from environmental exposures and thus an interesting candidate gene for the study of exposure-related lung disease. Lungs harvested from current versus former/never-smokers exhibited a 47% decrease in WWOX mRNA levels. Exposure to nicotine-containing e-cigarette vapor resulted in an average 57% decrease in WWOX mRNA levels relative to vehicle-treated controls. In separate studies, endothelial (EC)-specific WWOX knockout (KO) versus WWOX flox control mice were examined under ARDS-producing conditions. EC WWOX KO mice exhibited significantly greater levels of vascular leak and histologic lung injury. ECs were isolated from digested lungs of untreated EC WWOX KO mice using sorting by flow cytometry for CD31 CD45cells. These were grown in culture, confirmed to be WWOX deficient by RT-PCR and Western blotting, and analyzed by electric cell impedance sensing as well as an FITC dextran transwell assay for their barrier properties during methicillin-resistant or LPS exposure. WWOX KO ECs demonstrated significantly greater declines in barrier function relative to cells from WWOX flox controls during either methicillin-resistant or LPS treatment as measured by both electric cell impedance sensing and the transwell assay. The increased risk for ARDS observed in chronic smokers may be mechanistically linked, at least in part, to lung WWOX downregulation, and this phenomenon may also manifest in the near future in chronic users of e-cigarettes.
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http://dx.doi.org/10.1165/rcmb.2020-0145OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7780991PMC
January 2021

Death of the Endothelium in Sepsis: Understanding the Crime Scene.

Am J Respir Cell Mol Biol 2018 07;59(1):3-4

2 Division of Pulmonary, Critical Care, Sleep, and Occupational Medicine Indiana University Indianapolis, Indiana.

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http://dx.doi.org/10.1165/rcmb.2018-0051EDDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6039871PMC
July 2018

Micro-RNA-1 is decreased by hypoxia and contributes to the development of pulmonary vascular remodeling via regulation of sphingosine kinase 1.

Am J Physiol Lung Cell Mol Physiol 2018 03 22;314(3):L461-L472. Epub 2017 Nov 22.

Division of Pulmonary, Critical Care, Sleep, and Occupational Medicine, Indiana University , Indianapolis, Indiana.

Sphingosine kinase 1 (SphK1) upregulation is associated with pathologic pulmonary vascular remodeling in pulmonary arterial hypertension (PAH), but the mechanisms controlling its expression are undefined. In this study, we sought to characterize the regulation of SphK1 expression by micro-RNAs (miRs). In silico analysis of the SphK1 3'-untranslated region identified several putative miR binding sites, with miR-1-3p (miR-1) being the most highly predicted target. Therefore we further investigated the role of miR-1 in modulating SphK1 expression and characterized its effects on the phenotype of pulmonary artery smooth muscle cells (PASMCs) and the development of experimental pulmonary hypertension in vivo. Our results demonstrate that miR-1 is downregulated by hypoxia in PASMCs and can directly inhibit SphK1 expression. Overexpression of miR-1 in human PASMCs inhibits basal and hypoxia-induced proliferation and migration. Human PASMCs isolated from PAH patients exhibit reduced miR-1 expression. We also demonstrate that miR-1 is downregulated in mouse lung tissues during experimental hypoxia-mediated pulmonary hypertension (HPH), consistent with upregulation of SphK1. Furthermore, administration of miR-1 mimics in vivo prevented the development of HPH in mice and attenuated induction of SphK1 in PASMCs. These data reveal the importance of miR-1 in regulating SphK1 expression during hypoxia in PASMCs. A pivotal role is played by miR-1 in pulmonary vascular remodeling, including PASMC proliferation and migration, and its overexpression protects from the development of HPH in vivo. These studies improve our understanding of the molecular mechanisms underlying the pathogenesis of pulmonary hypertension.
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http://dx.doi.org/10.1152/ajplung.00057.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5900352PMC
March 2018

Hemin Causes Lung Microvascular Endothelial Barrier Dysfunction by Necroptotic Cell Death.

Am J Respir Cell Mol Biol 2017 09;57(3):307-314

Division of Pulmonary, Critical Care, Sleep, and Allergy Medicine, Department of Medicine, University of Illinois, Chicago, Illinois.

Hemin, the oxidized prosthetic moiety of hemoglobin, has been implicated in the pathogenesis of acute chest syndrome in patients with sickle cell disease by virtue of its endothelial-activating properties. In this study, we examined whether hemin can cause lung microvascular endothelial barrier dysfunction. By assessing transendothelial resistance using electrical cell impedance sensing, and by directly measuring trans-monolayer fluorescein isothiocyanate-dextran flux, we found that hemin does cause endothelial barrier dysfunction in a concentration-dependent manner. Pretreatment with either a Toll-like receptor 4 inhibitor, TAK-242, or an antioxidant, N-acetylcysteine, abrogated this effect. Increased monolayer permeability was found to be associated with programmed cell death by necroptosis, as evidenced by Trypan blue staining, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, Western blotting for activated forms of key effectors of cell death pathways, and studies utilizing specific inhibitors of necroptosis and apoptosis. Further studies examining the role of endothelial cell necroptosis in promoting noncardiogenic pulmonary edema during acute chest syndrome are warranted and may open a new avenue of potential treatments for this devastating disease.
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http://dx.doi.org/10.1165/rcmb.2016-0287OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5625223PMC
September 2017

Loss of lung WWOX expression causes neutrophilic inflammation.

Am J Physiol Lung Cell Mol Physiol 2017 06 10;312(6):L903-L911. Epub 2017 Mar 10.

Division of Pulmonary, Critical Care, Sleep, and Allergy Medicine, Department of Medicine, University of Illinois, Chicago, Illinois.

The tumor suppressor WW domain-containing oxidoreductase (WWOX) exhibits regulatory interactions with an array of transcription factors and signaling molecules that are positioned at the well-known crossroads between inflammation and cancer. WWOX is also subject to downregulation by genotoxic environmental exposures, making it of potential interest to the study of lung pathobiology. Knockdown of lung WWOX expression in mice was observed to cause neutrophil influx and was accompanied by a corresponding vascular leak and inflammatory cytokine production. In cultured human alveolar epithelial cells, loss of WWOX expression resulted in increased c-Jun- and IL-8-dependent neutrophil chemotaxis toward cell monolayers. WWOX was observed to directly interact with c-Jun in these cells, and its absence resulted in increased nuclear translocation of c-Jun. Finally, inhibition of the c-Jun-activating kinase JNK abrogated the lung neutrophil influx observed during WWOX knockdown in mice. Altogether, these observations represent a novel mechanism of pulmonary neutrophil influx that is highly relevant to the pathobiology and potential treatment of a number of different lung inflammatory conditions.
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http://dx.doi.org/10.1152/ajplung.00034.2017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5495942PMC
June 2017

Nicotinamide Phosphoribosyltransferase Promotes Pulmonary Vascular Remodeling and Is a Therapeutic Target in Pulmonary Arterial Hypertension.

Circulation 2017 04 15;135(16):1532-1546. Epub 2017 Feb 15.

From Division of Pulmonary, Critical Care Medicine, Sleep and Allergy, Department of Medicine (J.C., J.R.S., S.S., S.Z., A.Y., T.A., K.M.S., S.S., V.R., A.S., H.G., J.T., R.F.M.), Department of Pharmacology (J.R.S., R.F.M.), and Department of Bioengineering (A.V.-J., T.A.), University of Illinois at Chicago; Institute of Precision Medicine, Jining Medical University, China (J.C.); Department of Pharmacy, College of Pharmacy, Kinjo Gakuin University, Nagoya, Japan (A.Y.); Department of Medicine, Mercy Hospital and Medical Center, Chicago, IL (T.A.); Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.G.); Department of Medicine, University of Arizona, Tucson (S.M.C., H.T., J.X.-J.Y., J.G.N.G.); Department of Biomedical and Health Informatics and Department of Pediatrics, Children's Mercy Hospital and University of Missouri-Kansas City School of Medicine (S.Q.Y.); Department of Pathobiology, Lerner Research Institute, Pulmonary and Critical Care Medicine, Respiratory Institute, Cleveland Clinic, OH (S.C., R.D.); and Division of Pulmonary and Critical Care Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD (P.H.).

Background: Pulmonary arterial hypertension is a severe and progressive disease, a hallmark of which is pulmonary vascular remodeling. Nicotinamide phosphoribosyltransferase (NAMPT) is a cytozyme that regulates intracellular nicotinamide adenine dinucleotide levels and cellular redox state, regulates histone deacetylases, promotes cell proliferation, and inhibits apoptosis. We hypothesized that NAMPT promotes pulmonary vascular remodeling and that inhibition of NAMPT could attenuate pulmonary hypertension.

Methods: Plasma, mRNA, and protein levels of NAMPT were measured in the lungs and isolated pulmonary artery endothelial cells from patients with pulmonary arterial hypertension and in the lungs of rodent models of pulmonary hypertension. mice were exposed to 10% hypoxia and room air for 4 weeks, and the preventive and therapeutic effects of NAMPT inhibition were tested in the monocrotaline and Sugen hypoxia models of pulmonary hypertension. The effects of NAMPT activity on proliferation, migration, apoptosis, and calcium signaling were tested in human pulmonary artery smooth muscle cells.

Results: Plasma and mRNA and protein levels of NAMPT were increased in the lungs and isolated pulmonary artery endothelial cells from patients with pulmonary arterial hypertension, as well as in lungs of rodent models of pulmonary hypertension. mice were protected from hypoxia-mediated pulmonary hypertension. NAMPT activity promoted human pulmonary artery smooth muscle cell proliferation via a paracrine effect. In addition, recombinant NAMPT stimulated human pulmonary artery smooth muscle cell proliferation via enhancement of store-operated calcium entry by enhancing expression of Orai2 and STIM2. Last, inhibition of NAMPT activity attenuated monocrotaline and Sugen hypoxia-induced pulmonary hypertension in rats.

Conclusions: Our data provide evidence that NAMPT plays a role in pulmonary vascular remodeling and that its inhibition could be a potential therapeutic target for pulmonary arterial hypertension.
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http://dx.doi.org/10.1161/CIRCULATIONAHA.116.024557DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5400780PMC
April 2017

Expression profiling elucidates a molecular gene signature for pulmonary hypertension in sarcoidosis.

Pulm Circ 2016 Dec;6(4):465-471

Division of Pulmonary, Critical Care, Sleep and Allergy, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA.

Pulmonary hypertension (PH), when it complicates sarcoidosis, carries a poor prognosis, in part because it is difficult to detect early in patients with worsening respiratory symptoms. Pathogenesis of sarcoidosis occurs via incompletely characterized mechanisms that are distinct from the mechanisms of pulmonary vascular remodeling well known to occur in conjunction with other chronic lung diseases. To address the need for a biomarker to aid in early detection as well as the gap in knowledge regarding the mechanisms of PH in sarcoidosis, we used genome-wide peripheral blood gene expression analysis and identified an 18-gene signature capable of distinguishing sarcoidosis patients with PH ( = 8), sarcoidosis patients without PH ( = 17), and healthy controls ( = 45). The discriminative accuracy of this 18-gene signature was 100% in separating sarcoidosis patients with PH from those without it. If validated in a large replicate cohort, this signature could potentially be used as a diagnostic molecular biomarker for sarcoidosis-associated PH.
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http://dx.doi.org/10.1086/688316DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5210052PMC
December 2016

The imitation game in pulmonary arterial hypertension. Sex, bone morphogenetic protein receptor, and the estrogen paradox.

Am J Respir Crit Care Med 2015 Mar;191(6):612-3

1 Division of Pulmonary, Critical Care Medicine, Sleep and Allergy University of Illinois at Chicago Chicago, Illinois.

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http://dx.doi.org/10.1164/rccm.201501-0204EDDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5442984PMC
March 2015

Statins as a novel therapeutic strategy in acute lung injury.

Pulm Circ 2012 Oct;2(4):397-406

Institute for Personalized Respiratory Medicine, Section of Pulmonary, Critical Care, Sleep and Allergy, University of Illinois at Chicago, Chicago, Illinois, USA.

Acute lung injury (ALI) is a devastating clinical condition associated with pulmonary and systemic inflammation and characterized by incompetence of the pulmonary microvascular barrier culminating in noncardiogenic pulmonary edema. An understanding of the mechanisms underlying endothelial barrier dysfunction in ALI has been facilitated by study of the effects of statins in relevant cellular and animals models. Many of the pleotropic properties of these drugs, including direct effects on endothelial cell (EC) cytoskeletal rearrangement, NADPH oxidase, and nitric oxide activity, as well as effects on differential EC gene expression, are relevant to the pathobiology of ALI and suggest a potential therapeutic role for statins in this context. Moreover, results from preclinical studies and observations in relevant patient populations support the protective potential of statins in ALI, paving the way now for definitive clinical trials.
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http://dx.doi.org/10.4103/2045-8932.105028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3555410PMC
October 2012

Pro-inflammatory endothelial cell dysfunction is associated with intersectin-1s down-regulation.

Respir Res 2011 Apr 12;12:46. Epub 2011 Apr 12.

Pulmonary and Critical Care Medicine, Rush University Medical Center, 1750 W, Harrison Street, 297 Jelke, Chicago, IL 60612, USA.

Background: The response of lung microvascular endothelial cells (ECs) to lipopolysaccharide (LPS) is central to the pathogenesis of lung injury. It is dual in nature, with one facet that is pro-inflammatory and another that is cyto-protective. In previous work, overexpression of the anti-apoptotic Bcl-XL rescued ECs from apoptosis triggered by siRNA knockdown of intersectin-1s (ITSN-1s), a pro-survival protein crucial for ECs function. Here we further characterized the cyto-protective EC response to LPS and pro-inflammatory dysfunction.

Methods And Results: Electron microscopy (EM) analyses of LPS-exposed ECs revealed an activated/dysfunctional phenotype, while a biotin assay for caveolae internalization followed by biochemical quantification indicated that LPS causes a 40% inhibition in biotin uptake compared to controls. Quantitative PCR and Western blotting were used to evaluate the mRNA and protein expression, respectively, for several regulatory proteins of intrinsic apoptosis, including ITSN-1s. The decrease in ITSN-1s mRNA and protein expression were countered by Bcl-XL and survivin upregulation, as well as Bim downregulation, events thought to protect ECs from impending apoptosis. Absence of apoptosis was confirmed by TUNEL and lack of cytochrome c (cyt c) efflux from mitochondria. Moreover, LPS exposure caused induction and activation of inducible nitric oxide synthase (iNOS) and a mitochondrial variant (mtNOS), as well as augmented mitochondrial NO production as measured by an oxidation oxyhemoglobin (oxyHb) assay applied on mitochondrial-enriched fractions prepared from LPS-exposed ECs. Interestingly, expression of myc-ITSN-1s rescued caveolae endocytosis and reversed induction of iNOS expression.

Conclusion: Our results suggest that ITSN-1s deficiency is relevant for the pro-inflammatory ECs dysfunction induced by LPS.
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http://dx.doi.org/10.1186/1465-9921-12-46DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3096597PMC
April 2011

Efficacy and safety of dopamine versus norepinephrine in the management of septic shock.

Shock 2010 Apr;33(4):375-80

Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rush University Medical Center and Rush Medical College, Chicago, Illinois 60612, USA.

The optimum septic shock vasopressor support strategy is currently debated. This study was performed to evaluate the efficacy and safety of norepinephrine (NE) and dopamine (DA) as the initial vasopressor in septic shock patients who were managed with a specific treatment protocol. A prospective, randomized, open-label, clinical trial was used in a medical intensive care unit comparing DA with NE as the initial vasopressor in fluid-resuscitated 252 adult patients with septic shock. If the maximum dose of the initial vasopressor was unable to maintain the hemodynamic goal, then fixed-dose vasopressin was added to each regimen. If additional vasopressor support was needed to achieve the hemodynamic goal, then phenylephrine was added. The primary efficacy end point was all-cause 28-day mortality. Secondary end points included organ dysfunction, hospital and intensive care unit length of stay, and safety (primarily occurrence of arrhythmias). The 28-day mortality rate was 50% (67/134) with DA as the initial vasopressor compared with 43% (51/118) for NE treatment (P = 0.282). There was a significantly greater incidence of sinus tachycardia with DA (24.6%; 33/134) than NE (5.9%; 7/118) and arrhythmias noted with DA treatment (19.4%; 26/134) compared with NE treatment (3.4%; 4/118; P < 0.0001), respectively. Logistic regression analysis identified Acute Physiologic and Chronic Health Evaluation II score (P < 0.0001) and arrhythmia (P < 0.015) as significant predictors of outcome. In this protocol-directed vasopressor support strategy for septic shock, DA and NE were equally effective as initial agents as judged by 28-day mortality rates. However, there were significantly more cardiac arrhythmias with DA treatment. Patients receiving DA should be monitored for the development of cardiac arrhythmias (NCT00604019).
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http://dx.doi.org/10.1097/SHK.0b013e3181c6ba6fDOI Listing
April 2010
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