Enhanced susceptibility of nasal polyp tissues to avian and human influenza viruses

Transcriptomics unravels molecular changes associated with cilia and COVID-19 in chronic rhinosinusitis with nasal polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common upper respiratory tract complication where the pathogenesis is largely unknown. Herein, we investigated the transcriptome profile in nasal mucosa biopsies of CRSwNP patients and healthy individuals. We further integrated the transcriptomics data with genes located in chromosomal regions containing genome-wide significant gene variants for COVID-19. Among the most significantly upregulated genes in polyp mucosa were CCL18, CLEC4G, CCL13 and SLC9A3. Pathways involving "Ciliated epithelial cells" were the most differentially expressed molecular pathways when polyp mucosa and non-polyp mucosa from the same patient was compared. Natural killer T-cell (NKT) and viral pathways were the most statistically significant pathways in the mucosa of CRSwNP patients compared with those of healthy control individuals. Upregulated genes in polyp mucosa, located within the genome-wide associated regions of COVID-19, included LZTFL1, CCR9, SLC6A20, IFNAR1, IFNAR2 and IL10RB. Interestingly, the second most over-expressed gene in our study, CLEC4G, has been shown to bind directly to SARS-CoV-2 spike's N-terminal domain and mediate its entry and infection. Our results on altered expression of genes related to cilia and viruses point to the de-regulation of viral defenses in CRSwNP patients, and may give clues to future intervention strategies.

Expression of Neu5Acα2,3Gal and Neu5Acα2,6Gal on the nasal mucosa of patients with chronic rhinosinusitis and its possible effect on bacterial biofilm formation

OBJECTIVE

Adherence of pathogen to nasal mucosa and colonization is the first step of bacterial biofilm(BBF) formation in patients with chronic rhinosinusitis (CRS).Terminal sialic acids presenting on cell surface are potential targets for bacterial binding, thus may partly contribute to the pathogenesis of CRS. However, little has been published in this respect, the purpose of our study aimed to investigate the expression of sialic acids on the nasal mucosa in CRS patients and its possible effect on BBF formation.

METHODS

Sinus mucosa were harvested from CRS patients undergoing endoscopic surgery. The positive of BBF formation were detected by scanning electronic microscopy (SEM) and the expression of Neu5Acα2,3Gal(α2,3-linked sialic acid) and Neu5Acα2,6Gal(α2,6-linked sialic acid) on nasal mucosa were determined by fluorescent-immunohistochemical staining (F-IHC) with MAL-II and SNA respectively. A semi-quantitative scoring system was used to assess their different expression between CRS group and the control, as well as BBF positive and negative group.

RESULTS

Expression of Neu5Acα2,3Gal and Neu5Acα2,6Gal were both detected in the epithelium and submucosal glands of all 40 CRS patients and 23 controls, they were significantly up-regulated in CRS group(p < 0.05). Among 24 CRS patients, typical BBF formation were identified in 13 cases while the other 11 were regarded as negative, Between the subgroup of BBF(+) and BBF(-), both of Neu5Acα2,3Gal and Neu5Acα2,6Gal had a trend of increasing in BBF(+) group, however, the increased expression of Neu5Acα2,3Gal was statistical significance (4.77 ± 0.90 versus 3.45 ± 1.40; p = 0.0282), whereas the difference of Neu5Acα2,6Gal was insignificant(4.15 ± 1.27 versus 3.55 ± 1.59; p = 0.4281).

CONCLUSION

Expression of MAL-II binding (most probable Neu5Acα2,3Gal) and SNA binding (Neu5Acα2,6Gal) were up-regulated in inflamed nasal mucosa, and the increased expression of them may contribute to bacterial biofilm formation which deserved a further investigation.

The distribution of sialic acid receptors of avian influenza virus in the reproductive tract of laying hens

The susceptibility of the host to influenza virus is determined by the distribution of the sialic acid (SA) receptors on host cell membrane. Avian influenza virus (AIV) preferentially binds to SA α-2,3-galactose (SA α2,3-gal) linked receptors, while human strains bind to sialic acid α2,6-galactose (SA α2,6-gal) linked receptors. Here, we describe the SA patterns and distributions in the reproductive tract of hens by employing two specific lectins, Maackia amurensis agglutinin (MAA) for SA α2,3-gal and sambucus nigra agglutinin (SNA) for SA α 2,6-gal receptors. Our results revealed that both SA α2,3-gal and SA α2,6-gal receptors exist in the reproductive tract of hens, including magnum, isthmus, uterus and vagina except for infundibulum. The distribution of SAα-2,3-gal receptor was more abundantly in the columnar epithelium cells of magnum, isthmus and uterus. Only minimal positive results for SA α-2,6-gal receptors were detected in the columnar epithelium cells of magnum, isthmus, uterus and vagina. Furthermore, AIV in tissues of the reproductive tract tissues of laying hens were detected by SYBR green-based reverse transcription and polymerase chain reaction (RT-PCR). Results showed that both viral loads and pathological changes in different parts of the reproductive tract were positively correlated with the expression of both receptors. Our results revealed that the reproductive tract of hens may provide an environment for the replication of both avian and human influenza viruses.

Nasal epithelial repair and remodeling in physical injury, infection, and inflammatory diseases

PURPOSE OF REVIEW

To summarize the current knowledge of cellular and molecular mechanisms of nasal epithelial repair and remodeling during physical and pathophysiological conditions.

RECENT FINDINGS

Nasal epithelial repair and remodeling is a highly organized and well coordinated process, involving inflammation, proliferation, differentiation, matrix deposition, and remodeling, and is regulated by a wide variety of growth factors and cytokines. From the in-vivo and in-vitro studies conducted in both human and animal models, undifferentiated basal cells (progenitors) are able to migrate from adjacent epithelium, spread over the denuded basement membrane, and proliferate in injured regions (self-renewal) in necessary (homeostasis) or excessive (hyperplasia) degree. Progenitor cells reorient to an apical-basal polarity, and progressively differentiate into ciliated and nonciliated columnar cells and goblet cells, reconstituting a functional respiratory epithelium after several weeks. This recovery process can be observed during various types and severity of injury, and also in common nasal diseases, including acute viral, allergic, and nonallergic rhinitis, as well as chronic rhinosinusitis with and without nasal polyps.

SUMMARY

Although nearly 10 000 articles about nasal epithelium have been published in the last decade, the mechanisms underlying the nasal epithelial repair are still understood at only a superficial descriptive level. In order to advance rhinology to the next level of a comprehensive knowledge of the orchestrated genetic and molecular processes acting during epithelial repair, combined clinical and experimental studies using sophisticated investigational plans to elucidate the functions of both the protein-coding and regulatory portions of the human genome are required.

Atopic conditions other than asthma and risk of the 2009 novel H1N1 infection in children: a case-control study

A recent study showed an increased risk of 2009 novel H1N1 influenza (H1N1) infection among asthmatic children. Little is known whether this is true for other atopic conditions. This study was designed to determine the association between atopic dermatitis and/or allergic rhinitis and the risk of H1N1 infection among children. We conducted a case-control study in Olmsted County, MN. We randomly selected children ≤18 years of age with a positive test for H1N1. Controls were randomly selected from a pool of residents with negative H1N1 tests and were matched to cases with regard to birthday, gender, clinic registration date, diagnostic test, and month of influenza testing using frequency matching. We compared the frequency of atopic conditions other than asthma between cases and their matched controls. We enrolled 168 cases and 172 controls. Among cases, 91 (54.2%) were male patients, and 106 (63.1%) were white. The median age of cases was 6.3 years (interquartile range, 3.1-11.5). Among cases, 79 (47.0%) had atopic dermatitis and/or allergic rhinitis diagnosed before or after the index date, whereas 54 (31.4%) controls had such conditions (odds ratio [OR], 1.89; 95% CI, 1.15-3.12; p = 0.012, adjusting for asthma status, 2008-2009 seasonal influenza vaccine, time of illness at index date, and other comorbid conditions). History of receiving 2008-2009 seasonal influenza vaccine was associated with H1N1 infection (adjusted OR, 2.06; 95% CI, 1.32-3.28; p = 0.002). Our results suggest an association between H1N1 infection and atopic conditions other than asthma. The association between 2008-2009 seasonal influenza vaccinations and the risk of H1N1 requires further investigation.

Use of ex vivo and in vitro cultures of the human respiratory tract to study the tropism and host responses of highly pathogenic avian influenza A (H5N1) and other influenza viruses

The tropism of influenza viruses for the human respiratory tract is a key determinant of host-range, and consequently, of pathogenesis and transmission. Insights can be obtained from clinical and autopsy studies of human disease and relevant animal models. Ex vivo cultures of the human respiratory tract and in vitro cultures of primary human cells can provide complementary information provided they are physiologically comparable in relevant characteristics to human tissues in vivo, e.g. virus receptor distribution, state of differentiation. We review different experimental models for their physiological relevance and summarize available data using these cultures in relation to highly pathogenic avian influenza H5N1, in comparison where relevant, with other influenza viruses. Transformed continuous cell-lines often differ in important ways to the corresponding tissues in vivo. The state of differentiation of primary human cells (respiratory epithelium, macrophages) can markedly affect virus tropism and host responses. Ex vivo cultures of human respiratory tissues provide a close resemblance to tissues in vivo and may be used to risk assess animal viruses for pandemic threat. Physiological factors (age, inflammation) can markedly affect virus receptor expression and virus tropism. Taken together with data from clinical studies on infected humans and relevant animal models, data from ex vivo and in vitro cultures of human tissues and cells can provide insights into virus transmission and pathogenesis and may provide understanding that leads to novel therapeutic interventions.

The battle between influenza and the innate immune response in the human respiratory tract

Influenza is a viral infection of the respiratory tract. Infection is normally confined to the upper respiratory tract but certain viral strains have evolved the ability to infect the lower respiratory tract, including the alveoli, leading to inflammation and a disease pattern of diffuse alveolar damage. Factors leading to this sequence of events are novel influenza strains, or strains that have viral proteins, in particular the NS1 protein that allow it to escape the innate immune system. There are three main barriers that prevent infection of pneumocytes - mucin, host defence lectins and cells such as macrophages. Viruses have developed strategies such as neuraminidase and glycosylation patterns that allow this evasion. Though there has been much investment in antiviral drugs, it is proposed that more attention should be directed towards developing or utilizing compounds that enhance the ability of the innate immune system to combat viral infection.

Exacerbations of severe asthma

Exacerbations occur frequently in severe asthma. They result in significant morbidity and can lead to hospitalization and death. Severe exacerbations can also lead to an accelerated decline in lung function. Phenotyping severe asthma can aid with both prognostication of exacerbation risk and maintenance treatment selection to minimize future risks of exacerbations in severe asthma. The rate of exacerbations differs by phenotype, and is most frequent in refractory eosinophilic asthma and early onset allergic asthma. Phenotype specific therapy can reduce exacerbations in both these forms of severe asthma. Exacerbations are multi-component events. Each exacerbation represents an opportunity to assess and target treatment to the domains of airway pharmacotherapy, self-management behaviour, risk factors, and relevant co-morbidities.

Herpes simplex virus type 1 infection facilitates invasion of Staphylococcus aureus into the nasal mucosa and nasal polyp tissue

BACKGROUND

Staphylococcus aureus (S. aureus) plays an important role in the pathogenesis of severe chronic airway disease, such as nasal polyps. However the mechanisms underlying the initiation of damage and/or invasion of the nasal mucosa by S. aureus are not clearly understood. The aim of this study was to investigate the interaction between S. aureus and herpes simplex virus type 1 (HSV1) in the invasion of the nasal mucosa and nasal polyp tissue.

METHODOLOGY/PRINCIPAL FINDINGS

Inferior turbinate and nasal polyp samples were cultured and infected with either HSV1 alone, S. aureus alone or a combination of both. Both in turbinate mucosa and nasal polyp tissue, HSV1, with or without S. aureus incubation, led to focal infection of outer epithelial cells within 48 h, and loss or damage of the epithelium and invasion of HSV1 into the lamina propria within 72 h. After pre-infection with HSV1 for 24 h or 48 h, S. aureus was able to pass the basement membrane and invade the mucosa. Epithelial damage scores were significantly higher for HSV1 and S. aureus co-infected explants compared with control explants or S. aureus only-infected explants, and significantly correlated with HSV1-invasion scores. The epithelial damage scores of nasal polyp tissues were significantly higher than those of inferior turbinate tissues upon HSV1 infection. Consequently, invasion scores of HSV1 of nasal polyp tissues were significantly higher than those of inferior turbinate mucosa in the HSV1 and co-infection groups, and invasion scores of S. aureus of nasal polyp tissues were significantly higher than those of inferior turbinate tissues in the co-infection group.

CONCLUSIONS/SIGNIFICANCE

HSV1 may lead to a significant damage of the nasal epithelium and consequently may facilitate invasion of S. aureus into the nasal mucosa. Nasal polyp tissue is more susceptible to the invasion of HSV1 and epithelial damage by HSV1 compared with inferior turbinate mucosa.

Case report: Increased viral receptor expression associated with high viral load and severe pneumonia in a young patient infected with 2009 H1N1 influenza a with no pre-existing conditions

A case of unusually high severity of influenza pneumonia leading to acute respiratory distress syndrome and death was investigated. This was a previously a healthy 28-year-old man with no underlying conditions, admitted to a hospital during the first wave of influenza pandemic in Thailand in July 2009. He had experienced high fever and influenza-like illness for 5 days before coming to the hospital. He developed acute respiratory distress syndrome and expired on day 7 after admission. In comparison to three other cases of influenza pneumonia in the same outbreak with known risk factors for severe influenza, such as pregnancy and diabetes mellitus, a much higher viral load was detected in the lungs of this patient despite antiviral treatment. In agreement with the high viral load, the lung specimens from this patient, but not the other three patients, showed a high expression of α-2,6-linked sialic acid by lectin staining. The gene responsible for the synthesis of this sialic acid was also found to be upregulated. The data indicated overexpression of the viral receptor as a potential mechanism for severe disease in some patients.

Retinoic acid-inducible gene 1-like receptors in the upper respiratory tract

BACKGROUND

Retinoic acid-inducible gene 1-like receptors (RLRs) are a novel family of pattern recognition receptors that include retinoic acid-inducible gene 1 (RIG-1), melanoma differentiation-associated gene 5 (MDA-5), and laboratory of genomics and physiology 2 (LGP-2). The knowledge of RLRs and their function in the human airway is limited. This study explores the role of RLRs in the upper respiratory tract.

METHODS

Tonsils, adenoids, nasal polyps, and biopsy specimens from the nasal mucosa were examined for the occurrence of the RIG-1, MDA-5, and LGP-2 using real-time reverse-transcription polymerase chain reaction and immunohistochemistry. The nasopharyngeal epithelial cell line FaDu was cultured with the RIG-1/MDA-5 ligand poly(I:C)/LyoVec (Invivogen, San Diego, CA) and analyzed for cytokine release using ELISA.

RESULTS

RIG-1, MDA-5, and LGP-2 mRNA were found in all tissues tested. The airway epithelium appeared to be their most prominent location. The RIG-1 and MDA-5 mRNA levels were higher in nasal polyps than in normal nasal mucosa, a state that seemed to be reversed by local steroid treatment. Culture of FaDu with poly(I:C)/LyoVec resulted in IL-6 and IL-8 release. No alteration in RLR expression in tonsils was seen on infection.

CONCLUSION

This study shows the presence and functional activity of RLRs in the human upper airways. It also suggests a role for RLRs in nasal polyposis.