Ultrastructure of human nasal epithelium during an episode of coronavirus infection

Abstract

The nasal epithelium from a young girl was examined by electron microscopy and found to be infected by coronavirus. Virions are seen within and outside the ciliated cells, but not outside or within the goblet cells or other cells of the nasal mucosa. Some virions are located near the microvilli, others in pockets in the apical cell membrane. The cytoplasm contains many small vesicles with a single virion, large apical vesicles containing hundreds of virions, and lysosome-like cytosomes with a moderate number of virions. Some virus-like particles devoid of an electron-dense interior are seen both in the cytosomes and extracellularly. Virus budding was observed in the Golgi apparatus but nowhere else in the cell. The ciliated cells seem not to be destroyed by the viruses, although in many cases the cilia are withdrawn into the cell body. The loss of cilia is likely to cause rhinorrhoea.

Activity of budesonide on nasal neutrophilic inflammation and obstruction in children with recurrent upper airway infections

“…Viral or bacterial respiratory infections have been shown to heavily decrease or abrogate mucociliary clearance, thus decreasing a key physical defense mechanism and facilitating recurrency [26]. Upper respiratory tract infections also induce the activation of various resident cell types, including nasal epithelial cells [27], but release of cytokines and chemotactic factors able to recruit and activate polymorphonuclear leukocytes, have been reported also outside of acute episodes in patients with chronic/recurrent upper respiratory tract diseases [1][2][3][4][5][6][7][8][26][27][28].…”

“…Upper respiratory tract infections also induce the activation of various resident cell types, including nasal epithelial cells [27], but release of cytokines and chemotactic factors able to recruit and activate polymorphonuclear leukocytes, have been reported also outside of acute episodes in patients with chronic/recurrent upper respiratory tract diseases [1][2][3][4][5][6][7][8][26][27][28]. Consistent with these findings, nasal neutrophilic inflammation was present in all children here evaluated, suggesting that an ongoing recruitment of polymorphonuclear leukocytes was present.…”

The effects of coronavirus on human nasal ciliated respiratory epithelium

“…In contrast, there are many published reports of in vitro coronavirus-infected cells [26][27][28]. AFZELIUS [11] documented a single case of coronavirus infection of the nasal respiratory epithelium in a 2-yr-old girl with no symptoms of a common cold. This was an incidental finding on a biopsy taken to rule out the diagnosis of primary ciliary dyskinesia.…”

“…Other data include an incidental finding, on electron microscopy, of HCoV infection in a 2-yr-old female being investigated for ciliary dyskinesia. It is of interest that this infection was asymptomatic with no signs of a common cold at the time of biopsy or afterwards [11].…”

Pathophysiology of Allergic Rhinitis

“…Sulfur dioxide causes nasal congestion as well as an increase in both mast cells and lymphocytes in nasal lav age fluids. Tobacco smoking or passive smoking can in some patients induce a nasal reaction interfering with al lergens by inducing symptoms of rhinitis [159], Viral in fections are known to induce the activation of various cell types including nasal epithelial cells [160] and the release of various cytokines [161,162], Cold air can induce an inflam matory response with the activation of mast cells [163,164] and the occurrence of a L PR [165], …”