Nicotine Changes Airway Epithelial Phenotype and May Increase the SARS-COV-2 Infection Severity.

Leonardo Lupacchini,Fabrizio Maggi,Patrizia Russo,Chiara De Dominicis,Cristiana Mollinari,Daniela Merlo,Carlo Tomino,Massimo Fini,Stefano Bonassi

doi:10.3390/molecules26010101

Abstract

(1) Background: Nicotine is implicated in the SARS-COV-2 infection through activation of the α7-nAChR and over-expression of ACE2. Our objective was to clarify the role of nicotine in SARS-CoV-2 infection exploring its molecular and cellular activity. (2) Methods: HBEpC or si-mRNA-α7-HBEpC were treated for 1 h, 48 h or continuously with 10−7 M nicotine, a concentration mimicking human exposure to a cigarette. Cell viability and proliferation were evaluated by trypan blue dye exclusion and cell counting, migration by cell migration assay, senescence by SA-β-Gal activity, and anchorage-independent growth by cloning in soft agar. Expression of Ki67, p53/phospho-p53, VEGF, EGFR/pEGFR, phospho-p38, intracellular Ca2+, ATP and EMT were evaluated by ELISA and/or Western blotting. (3) Results: nicotine induced through α7-nAChR (i) increase in cell viability, (ii) cell proliferation, (iii) Ki67 over-expression, (iv) phospho-p38 up-regulation, (v) EGFR/pEGFR over-expression, (vi) increase in basal Ca2+ concentration, (vii) reduction of ATP production, (viii) decreased level of p53/phospho-p53, (ix) delayed senescence, (x) VEGF increase, (xi) EMT and consequent (xii) enhanced migration, and (xiii) ability to grow independently of the substrate. (4) Conclusions: Based on our results and on evidence showing that nicotine potentiates viral infection, it is likely that nicotine is involved in SARS-CoV-2 infection and severity.

Highlights

Nicotine (Table 1) [1,2,3,4,5,6,7,8,9] is the addictive compound of tobacco and exerts its effect after binding to nAChR [10,11,12]
(4) Conclusions: Based on our results and on evidence showing that nicotine potentiates viral infection, it is likely that nicotine is involved in SARS-CoV-2 infection and severity
Human Bronchial Epithelial Cells (HBEpC), which reached the level of 0.56 ± 0.11 and 1.33 ± 0.31 ng/mL, increasing by 138% with respect to untreated cell (Figure 6A,B) and 0.58 ± 0.08 IU/mL and 1.14 ± 0.09 IU/mL with an increase of 97.2%, respectively (Figure 6C,D). si-mRNA-α7-HBEpC showed a low level of both EGFR and pEGFR that did not increase after nicotine exposure (Figure 6)

Summary

Introduction

Nicotine (Table 1) [1,2,3,4,5,6,7,8,9] is the addictive compound of tobacco and exerts its effect after binding to nAChR [10,11,12]. ACh is the natural ligand of both nAChR and mAChR. Nicotine binds with high affinity to the α4β2-nAChR with a Ki = 1 nM inducing a desensitized state that in turn reduces functional activity of the α4β2-nAChR [13], and with low affinity binding to the α7 receptor with Ki = 1600 nM [14]. This observation is important because means that α4β2-nAChR are desensitized by nicotine and are not able to function. The role of the α7 receptor is the best characterized on the lung [12]

Objectives

Methods

Results