Biology subjects

Caohuy, H.

Publications and source records attributed to Caohuy, H..

3 recordsLinked to original sources

bioRxiv2026

PM2.5 toxin benzopyrene induces life-limiting inflammation and oxidative stress in the airway by up-regulation of TRPC6 and inactivation of β2AR/CFTR signaling

Abstract2O_ST_ABSBackgroundC_ST_ABSSustained exposures to high atmospheric levels of PM2.5 at population scale are associated with increased risks for pulmonary inflammatory diseases. These are marked by activation of the TRPC6 (Transient Receptor Potential Canonical type 6) calcium channel, increased reactive oxygen species (ROS) and oxidative stress. Long term exposures are associated with reduced life span, and increased incidences of cardiovascular diseases, dementia, Parkinsons and Alzheimer disease, and increased risk of autism and autism spectrum disorders. It has been proposed that the PM2.5 toxin is benzo[a]pyrene (B[a]P) that is adsorbed to the surface of the PM2.5 particle.. But the mechanism by which B[a]P might drive pulmonary inflammatory diseases, or any other of the indications above, are not known. HypothesisB[a]P was recently reported to bind irreversibly and destructively to the {beta}2 Adrenergic Receptor ({beta}2AR) in the lung. We have therefore hypothesized that B[a]P is the adsorbed PM2.5 toxin, and that {beta}2AR is the B[a]P receptor responsible for TRPC6 activation in lung epithelial cells. ResultsTo test this hypothesis, we exposed a polarized organoid model of normal human lung epithelia, polarized lung epithelial 16HBE14o-cells, and tracheobronchial slice cultures from ferret lung to either PM2.5 or B[a]P. We found that both PM2.5 and B[a]P: (i) irreversibly activated of {beta}2AR signaling via Gi to PI3K/AKT; (ii) increased NF{kappa}B-activated release of proinflammatory cytokines through IKK{beta} activation by PI3K/AKT, which was suppressed by the PI3K inhibitor LY 294002 (iii) desensitized and destroyed the activated {beta}2AR receptor by endocytic recycling; (iv) also destroyed {beta}2ARs signalplex partner CFTR by the same process; (v) activated the CFTR-bound calcium channel protein TRPC6 due to loss of inhibitory CFTR; leading to (vi) increased cytosolic [Ca2+] concentration; (vii) increased ROS due to mitochondrial uncoupling; and (viii) increased expression of oxidative stress. Treatment with the TRPC6 inhibitor BI 749327 blocked steps (vi-viii), and preserved CFTR from endocytic loss. Treatment of tracheobronchial slice cultures of ferret lung with either PM2.5 or B[a]P resulted in increased secretion of IL-6, increased expression of TRPC6, and reduced expression of {beta}2AR and CFTR. Finally, we found that exposure of lung organoids to B[a]P significantly reduced expression of the same five microRNAs (miR-126a-3p, miR-30b-5p, miR-103a-3p, miR-26a-5p, and miR-766-3p) previously identified in sera from service members exposed to PM2.5 from burn pit emissions during deployment to Iraq and Afghanistan. ConclusionPM2.5 and the PM2.5 toxin benzo[a]pyrene (B[a]P) induce inflammation and oxidative stress in the airway by increased expression of TRPC6 and inactivation of {beta}2AR/CFTR signaling. These discoveries mark the first identification of a mechanism by which exposure to PM2.5 or the PM2.5 toxin B[a]P itself can induce inflammation and TRPC6-dependent oxidative stress in lung epithelia.

pharmacology and toxicology↗

bioRxiv2022

Inflammation in the COVID-19 airway is due to inhibition of CFTR signaling by the SARS-CoV-2 Spike protein

BackgroundSARS-CoV-2-contributes to sickness and death in COVID-19 patients partly by inducing a hyper-proinflammatory immune response in the host airway. This hyper- proinflammatory state involves activation of signaling by NF{kappa}B and ENaC, and expression of high levels of cytokines and chemokines. Post-infection inflammation may contribute to "Long COVID", and there are long term consequences for acute severe COVID-19, which double or triple the chances of dying from any cause within a year. Enhanced signaling by NF{kappa}B and ENaC also marks the airway of patients suffering from cystic fibrosis, a lethal proinflammatory genetic disease due to inactivating mutations in the CFTR gene. We therefore hypothesized that inflammation in the COVID-19 airway might be due to inhibition of CFTR signaling by SARS- CoV-2 Spike protein. MethodsThis hypothesis was tested using the hTERT-transformed BCi-NS1.1 basal stem cell, previously derived from small airway epithelia, which were differentiated into a model of small airway epithelia on an air-liquid-interface (ALI). CyclicAMP-activated CFTR chloride channel activity was measured using an Ussing Chamber. Cell surface-CFTR was labeled with the impermeant biotin method. ResultsExposure of differentiated airway epithelia to SARS-CoV-2 Spike protein resulted in loss of CFTR protein expression. As hypothesized, TNF/NF{kappa}B signaling was activated, based on increased protein expression of TNFR1, the TNF receptor; TRADD, the first intracellular adaptor for the TNF/TNFR1 complex; phosphorylated I{kappa}B, and the chemokine IL8. ENaC activity was also activated, based on specific changes in molecular weights for and {gamma} ENaC. Exposure of the epithelia to viral Spike protein suppressed cAMP-activated CFTR chloride channel activity. However, 30 nM concentrations of cardiac glycoside drugs ouabain, digitoxin and digoxin, prevented loss of channel activity. ACE2 and CFTR were found to co- immunoprecipitate (co-IP) in both basal cells and epithelia, suggesting that the mechanism for Spike-dependent CFTR loss might involve ACE2 as a bridge between Spike and CFTR. In addition, Spike exposure to the epithelia resulted in failure of endosomal recycling to return CFTR to the plasma membrane, suggesting that failure of CFTR recovery from endosomal recycling might be a mechanism for spike-dependent loss of CFTR. ConclusionBased on experiments with this model of small airway epithelia, we predict that inflammation in the COVID-19 airway may be mediated by inhibition of CFTR signaling by SARS-CoV-2 Spike protein, thus inducing a CFTR-null, cystic fibrosis-like clinical phenotype.

microbiology↗

bioRxiv2021

Common cardiac medications potently inhibit ACE2 binding to the SARS-CoV-2 Spike, and block virus penetration into human lung cells

To initiate SARS-CoV-2 infection, the Receptor Binding Domain (RBD) on the viral spike protein must first bind to the host receptor ACE2 protein on pulmonary and other ACE2-expressing cells. We hypothesized that cardiac glycoside drugs might block the binding reaction between ACE2 and the Spike (S) protein, and thus block viral penetration into target cells. To test this hypothesis we developed a biochemical assay for ACE2:Spike binding, and tested cardiac glycosides as inhibitors of binding. Here we report that ouabain, digitoxin, and digoxin are high-affinity competitive inhibitors of ACE2 binding to the Wuhan S1 and the European [E614G] S1 proteins. These drugs also inhibit ACE2 binding to the Wuhan RBD, as well as to RBD proteins containing the S. Africa [E484K], Mink [Y453F] and UK [N501Y] mutations. As hypothesized, we also found that ouabain and digitoxin blocked penetration by SARS-CoV-2 Spike-pseudotyped virus into human lung cells. These data indicate that cardiac glycosides may block viral penetration into the target cell by first inhibiting ACE2:Spike binding. Clinical concentrations of ouabain and digitoxin are relatively safe for short term use for subjects with normal hearts. It has therefore not escaped our attention that these common cardiac medications could be deployed worldwide as inexpensive repurposed drugs for anti-COVID-19 therapy.

pharmacology and toxicology↗