Host transcriptional responses in nasal swabs identify potential SARS-CoV-2 infection in PCR negative patients

Unveiling the prevalence and impact of silent rhinovirus infection in chronic rhinosinusitis with nasal polyps

BACKGROUND

Chronic rhinosinusitis with nasal polyps (CRSwNPs) involves persistent sinus inflammation, with emerging evidence suggesting a potential role of rhinovirus (RV) in its pathophysiology. However, whether RV exists in nasal tissues and affects the nasal mucosa after the resolution of infection symptoms remains unknown.

OBJECTIVE

To investigate the prevalence and impact of silent RV infection in nasal tissues.

METHODS

RV loads were detected in the nasal tissues of 47 controls and 101 patients with CRSwNP without respiratory infection. Participants were categorized into RV-positive (+), RV-negative (-), and the "gray zone" groups. Quantitative polymerase chain reaction, Western blotting, and immunofluorescence assays were used to analyze the impact of silent RV infection on the immune status of nasal tissues.

RESULTS

Silent RV infection was prevalent in both control (34%) and CRSwNP (30.7%) tissues, with higher viral loads observed in the nasal polyps. In controls, it was associated with high expression of types 1 and 2 interferon (IFN), type 2 inflammation, interleukin (IL)-17A, and IL-10. In patients with CRSwNP, silent RV infection was associated with lower levels of type 1 IFN, IL-17A, type 2 inflammation, and IL-10 but higher levels of type 2 IFN compared with those without RV infection. Meanwhile, RV (+) nasal polyps exhibited fewer tissue eosinophils and neutrophils than RV (-) nasal polyps.

CONCLUSION

Silent RV infection was prevalent in the nasal tissues, with a higher viral load detected in the nasal polyps. This silent RV infection is associated with distinct immune responses in healthy controls and patients with CRSwNP, involving differential modulation of IFNs, TH2 cytokines, IL-17A, IL-10, and eosinophil and neutrophil levels.

Metatranscriptomic profiling reveals pathogen and host response signatures of pediatric acute sinusitis and upper respiratory infection

BACKGROUND

Acute sinusitis (AS) is a frequent cause of antibiotic prescriptions in children. Distinguishing bacterial AS from common viral upper respiratory infections (URIs) is crucial to prevent unnecessary antibiotic use but is challenging with current diagnostic methods. Despite its speed and cost, untargeted RNA sequencing of clinical samples from children with suspected AS has the potential to overcome several limitations of other methods. In addition, RNA-seq may reveal novel host-response biomarkers for development of future diagnostic assays that distinguish bacterial from viral infections. There are however no available RNA-seq datasets of pediatric AS that provide a comprehensive view of both pathogen etiology and host immune response.

METHODS

Here, we performed untargeted RNA-seq (metatranscriptomics) of nasopharyngeal samples from 221 children with AS and performed a comprehensive analysis of pathogen etiology and the impact of bacterial and viral infections on host immune responses. Accuracy of RNA-seq-based pathogen detection was evaluated by comparison with culture tests for three common bacterial pathogens and qRT-PCR tests for 12 respiratory viruses. Host gene expression patterns were explored to identify potential host responses that distinguish bacterial from viral infections.

RESULTS

RNA-seq-based pathogen detection showed high concordance with culture or qRT-PCR, showing 87%/81% sensitivity (sens) / specificity (spec) for detecting three AS-associated bacterial pathogens, and 86%/92% (sens/spec) for detecting 12 URI-associated viruses, respectively. RNA-seq also detected an additional 22 pathogens not tested for clinically and identified plausible pathogens in 11/19 (58%) of cases where no organism was detected by culture or qRT-PCR. We reconstructed genomes of 196 viruses across the samples including novel strains of coronaviruses, respiratory syncytial virus, and enterovirus D68, which provide useful genomic data for ongoing pathogen surveillance programs. By analyzing host gene expression, we identified host-response signatures that differentiate bacterial and viral infections, revealing hundreds of candidate gene biomarkers for future diagnostic assays.

CONCLUSIONS

Our study provides a one-of-kind dataset that profiles the interplay between pathogen infection and host responses in pediatric AS and URI. It reveals bacterial and viral-specific host responses that could enable new diagnostic approaches and demonstrates the potential of untargeted RNA-seq in diagnostic analysis of AS and URI.

Longitudinal host transcriptional responses to SARS-CoV-2 infection in adults with extremely high viral load

Current understanding of viral dynamics of SARS-CoV-2 and host responses driving the pathogenic mechanisms in COVID-19 is rapidly evolving. Here, we conducted a longitudinal study to investigate gene expression patterns during acute SARS-CoV-2 illness. Cases included SARS-CoV-2 infected individuals with extremely high viral loads early in their illness, individuals having low SARS-CoV-2 viral loads early in their infection, and individuals testing negative for SARS-CoV-2. We could identify widespread transcriptional host responses to SARS-CoV-2 infection that were initially most strongly manifested in patients with extremely high initial viral loads, then attenuating within the patient over time as viral loads decreased. Genes correlated with SARS-CoV-2 viral load over time were similarly differentially expressed across independent datasets of SARS-CoV-2 infected lung and upper airway cells, from both in vitro systems and patient samples. We also generated expression data on the human nose organoid model during SARS-CoV-2 infection. The human nose organoid-generated host transcriptional response captured many aspects of responses observed in the above patient samples, while suggesting the existence of distinct host responses to SARS-CoV-2 depending on the cellular context, involving both epithelial and cellular immune responses. Our findings provide a catalog of SARS-CoV-2 host response genes changing over time and magnitude of these host responses were significantly correlated to viral load.

Nasopharyngeal metatranscriptomics reveals host-pathogen signatures of pediatric sinusitis

Acute sinusitis (AS) is the fifth leading cause of antibiotic prescriptions in children. Distinguishing bacterial AS from common viral upper respiratory infections in children is crucial to prevent unnecessary antibiotic use but is challenging with current diagnostic methods. Despite its speed and cost, untargeted RNA sequencing of clinical samples from children with suspected AS has the potential to overcome several limitations of other methods. However, the utility of sequencing-based approaches in analysis of AS has not been fully explored. Here, we performed RNA-seq of nasopharyngeal samples from 221 children with clinically diagnosed AS to characterize their pathogen and host-response profiles. Results from RNA-seq were compared with those obtained using culture for three common bacterial pathogens and qRT-PCR for 12 respiratory viruses. Metatranscriptomic pathogen detection showed high concordance with culture or qRT-PCR, showing 87%/81% sensitivity (sens) / specificity (spec) for detecting bacteria, and 86%/92% (sens/spec) for viruses, respectively. We also detected an additional 22 pathogens not tested for in the clinical panel, and identified plausible pathogens in 11/19 (58%) of cases where no organism was detected by culture or qRT-PCR. We assembled genomes of 205 viruses across the samples including novel strains of coronaviruses, respiratory syncytial virus (RSV), and enterovirus D68. By analyzing host gene expression, we identified host-response signatures that distinguished bacterial and viral infections and correlated with pathogen abundance. Ultimately, our study demonstrates the potential of untargeted metatranscriptomics for in depth analysis of the etiology of AS, comprehensive host-response profiling, and using these together to work towards optimized patient care.

Longitudinal host transcriptional responses to SARS-CoV-2 infection in adults with extremely high viral load

Current understanding of viral dynamics of SARS-CoV-2 and host responses driving the pathogenic mechanisms in COVID-19 is rapidly evolving. Here, we conducted a longitudinal study to investigate gene expression patterns during acute SARS-CoV-2 illness. Cases included SARS-CoV-2 infected individuals with extremely high viral loads early in their illness, individuals having low SARS-CoV-2 viral loads early in their infection, and individuals testing negative for SARS-CoV-2. We could identify widespread transcriptional host responses to SARS-CoV-2 infection that were initially most strongly manifested in patients with extremely high initial viral loads, then attenuating within the patient over time as viral loads decreased. Genes correlated with SARS-CoV-2 viral load over time were similarly differentially expressed across independent datasets of SARS-CoV-2 infected lung and upper airway cells, from both in vitro systems and patient samples. We also generated expression data on the human nose organoid model during SARS-CoV-2 infection. The human nose organoid-generated host transcriptional response captured many aspects of responses observed in the above patient samples, while suggesting the existence of distinct host responses to SARS-CoV-2 depending on the cellular context, involving both epithelial and cellular immune responses. Our findings provide a catalog of SARS-CoV-2 host response genes changing over time.