The epithelial barrier theory and its associated diseases.

The prevalence of many chronic noncommunicable diseases has been steadily rising over the past six decades. During this time, over 350,000 new chemical substances have been introduced to the lives of humans. In recent years, the epithelial barrier theory came to light explaining the growing prevalence and exacerbations of these diseases worldwide. It attributes their onset to a functionally impaired epithelial barrier triggered by the toxicity of the exposed substances, associated with microbial dysbiosis, immune system activation, and inflammation. Diseases encompassed by the epithelial barrier theory share common features such as an increased prevalence after the 1960s or 2000s that cannot (solely) be accounted for by the emergence of improved diagnostic methods. Other common traits include epithelial barrier defects, microbial dysbiosis with loss of commensals and colonization of opportunistic pathogens, and circulating inflammatory cells and cytokines. In addition, practically unrelated diseases that fulfill these criteria have started to emerge as multimorbidities during the last decades. Here, we provide a comprehensive overview of diseases encompassed by the epithelial barrier theory and discuss evidence and similarities for their epidemiology, genetic susceptibility, epithelial barrier dysfunction, microbial dysbiosis, and tissue inflammation.

Promoting patient-centred care in the management of allergic rhinitis in Asia-Pacific countries.

Background: Allergic rhinitis (AR) has a high burden of disease in the Asia-Pacific region (APAC). Although guidelines provide recommendations regarding the diagnosis and treatment of AR, it is increasingly being recognised that there are gaps in their implementation. Patient-centred care involves accounting for the specific needs and desires of patients as well as including the patient in the decision-making process, and this may provide a means to reduce these gaps and consequently the burden of AR. Methods: A group of 11 experts in immunology and otorhinolaryngology from APAC provided information regarding their practices and experiences in the management of AR through an online survey. The group then discussed the barriers and solutions for the implementation of patient-centred care across the patient journey in a face-to-face meeting. Results: Key barriers to the implementation of patient-centred care for AR in APAC included a lack of patient awareness of the condition and treatment options, low adherence to treatments, financial constraints for patients, and time constraints for physicians. The solutions proposed include improving the knowledge of the patients about their conditions, the use of shared decision-making, the consideration of patient characteristics when choosing treatments, and the use of outcome measures to aid the optimisation of patient care. We provide specific recommendations for clinical practice. Conclusion: A greater focus on patient-centred approaches has the potential to improve the management of AR in APAC. More emphasis should be placed on each patient's specific health needs and desired outcomes.

Prodrug-conjugated tumor-seeking commensals for targeted cancer therapy.

Prodrugs have been explored as an alternative to conventional chemotherapy; however, their target specificity remains limited. The tumor microenvironment harbors a range of microorganisms that potentially serve as tumor-targeting vectors for delivering prodrugs. In this study, we harness bacteria-cancer interactions native to the tumor microbiome to achieve high target specificity for prodrug delivery. We identify an oral commensal strain of Lactobacillus plantarum with an intrinsic cancer-binding mechanism and engineer the strain to enable the surface loading of anticancer prodrugs, with nasopharyngeal carcinoma (NPC) as a model cancer. The engineered commensals show specific binding to NPC via OppA-mediated recognition of surface heparan sulfate, and the loaded prodrugs are activated by tumor-associated biosignals to release SN-38, a chemotherapy compound, near NPC. In vitro experiments demonstrate that the prodrug-loaded microbes significantly increase the potency of SN-38 against NPC cell lines, up to 10-fold. In a mouse xenograft model, intravenous injection of the engineered L. plantarum leads to bacterial colonization in NPC tumors and a 67% inhibition in tumor growth, enhancing the efficacy of SN-38 by 54%.

An unusually high prevalence of allergic rhinitis at high altitudes in 6-7 year old children - An epidemiological study.

Objectives: To compare the epidemiology and disease patterns of allergic rhinitis (AR) at 2 different altitudes in children aged 6-7 years, and subsequently to compare with and augment data from international studies. Materials and methods: This is a multistage, clustered and stratified random sample study. The study area comprises 2 distinct areas within Yunnan Province, China. Low altitude was represented by Xishuangbanna Prefecture (XB), while high altitude was represented by Diqing Prefecture (DiQ). Each study area was subdivided into 3 sub-areas, and children aged 6-7 years were randomly sampled based on proportion-weighted sampling. The area studied includes the well-known area of Shangri-La city. Questionnaires were distributed and jointly completed by study participants and their parents or guardians, under the guidance of professional medical staff. Results: 2796 valid questionnaires out of 2933 distributed were obtained (survey response rate 95.3%). The prevalence of AR is statistically significantly higher at high altitude (DiQ, 36.0%, 95%CI 33.2-38.8) as compared to low altitude (XB, 19.7%, 95%CI 17.8-21.6) (p < 0.001). Both areas studied had a greater prevalence of AR compared to international data. In both XB and DiQ, male gender, history of early antibiotic use, urban place of birth and place of residence, presence of smokers within the same household, family history of allergic diseases (such as atopic dermatitis), as well as higher parental educational level were all associated with a higher prevalence of AR (p < 0.05). In DiQ, the prevalence of AR in Han ethnicity was greater than that of ethnic minorities (p < 0.05). In XB, being a single child was associated with an increased prevalence of AR compared to those who had siblings (p < 0.05). Conclusion: Our study found that the prevalence of AR is relatively greater at higher altitudes. Genetic and environmental factors both play an important role in the pathogenesis of AR. While altitude may be an important environmental factor, confounding factors may include humidity, temperature and distribution pattern of common aeroallergens.

Updated epithelial barrier dysfunction in chronic rhinosinusitis: Targeting pathophysiology and treatment response of tight junctions.

Tight junction (TJ) proteins establish a physical barrier between epithelial cells, playing a crucial role in maintaining tissue homeostasis by safeguarding host tissues against pathogens, allergens, antigens, irritants, etc. Recently, an increasing number of studies have demonstrated that abnormal expression of TJs plays an essential role in the development and progression of inflammatory airway diseases, including chronic obstructive pulmonary disease, asthma, allergic rhinitis, and chronic rhinosinusitis (CRS) with or without nasal polyps. Among them, CRS with nasal polyps is a prevalent chronic inflammatory disease that affects the nasal cavity and paranasal sinuses, leading to a poor prognosis and significantly impacting patients' quality of life. Its pathogenesis primarily involves dysfunction of the nasal epithelial barrier, impaired mucociliary clearance, disordered immune response, and excessive tissue remodeling. Numerous studies have elucidated the pivotal role of TJs in both the pathogenesis and response to traditional therapies in CRS. We therefore to review and discuss potential factors contributing to impair and repair of TJs in the nasal epithelium based on their structure, function, and formation process.

Multicenter effect analysis of one-step acellular dermis combined with autologous ultra-thin split thickness skin composite transplantation in treating burn and traumatic wounds.

To evaluate the efficacy of one-step acellular dermis combined with autologous split thickness skin grafting in the treatment of burn or trauma wounds by a multicenter controlled study. In patients with extensive burns, it is even difficult to repair the wounds due to the shortage of autologous skin. The traditional skin grafting method has the disadvantages of large damage to the donor site, insufficient skin source and unsatisfactory appearance, wear resistance and elasticity of the wound tissue after skin grafting. One-step acellular dermis combined with autologous ultra-thin split thickness skin graft can achieve better healing effect in the treatment of burn and trauma wounds. A total of 1208 patients who underwent single-layer skin grafting and one-step composite skin grafting in the First Affiliated Hospital of Wannan Medical College, Wuhan Third People's Hospital and Lu 'an People's Hospital from 2019 to 2022 were retrospectively analysed. The total hospitalization cost, total operation cost, hospitalization days after surgery, wound healing rate after 1 week of skin grafting and scar follow-up at 6 months after discharge were compared and studied. The total cost of hospitalization and operation in the composite skin grafting group was significantly higher than those in the single-layer autologous skin grafting group. The wound healing rate after 1 week of skin grafting and the VSS score of scar in the follow-up of 6 months after discharge were better than those in the single-layer skin grafting group. One-step acellular dermis combined with autologous ultra-thin split thickness skin graft has high wound healing rate, less scar, smooth appearance and good elasticity in repairing burn and trauma wounds, which can provide an ideal repair method for wounds.

Epithelial Tight Junction Anomalies in Nasal Inverted Papilloma.

OBJECTIVES: As a critical component of the epithelial barrier, tight junctions (TJs) are essential in nasal mucosa against pathogen invasion. However, the function of TJs has rarely been reported in nasal inverted papilloma (NIP). This study aims to investigate the potential factors of TJs' abnormality in NIP. METHODS: We assessed the expression of ZO-1, occludin, claudin-1, claudin-3, and claudin-7 in healthy controls and NIP by real-time quantitative polymerase chain reaction and immunofluorescent staining. The correlation between TJs expression and neutrophil count, TH 1/TH 2/TH 17 and regulatory T cell biomarkers, and the proportion of nasal epithelial cells was investigated. RESULTS: Upregulation of ZO-1, occludin, claudin-1, and claudin-7, along with downregulation of claudin-3, was found in NIP compared to control (all p < 0.05). An abnormal proportion with a lower number of ciliated cells (control vs. NIP: 37.60 vs. 8.67) and goblet cells (12.52 vs. 0.33) together with a higher number of basal cells (45.58 vs. 124.00) in NIP. Meanwhile, claudin-3 was positively correlated with ciliated and goblet cells (all p < 0.01). Additionally, neutrophils were excessively infiltrated in NIP, negatively correlated with ZO-1, but positively with claudin-3 (all p < 0.05). Furthermore, FOXP3, IL-10, TGF-ß1, IL-5, IL-13, and IL-22 levels were induced in NIP (all p < 0.01). Occludin level was negatively correlated with IL-10, IL-5, IL-13, and IL-22, whereas ZO-1 was positively with TGF-ß1 (all p < 0.05). CONCLUSION: Nasal epithelial barrier dysfunction with TJs anomalies is commonly associated with abnormal proliferation and differentiation of epithelial cells and imbalance of immune and inflammatory patterns in NIP. LEVEL OF EVIDENCE: NA Laryngoscope, 134:552-561, 2024.

Type 2 Biomarkers for the Indication and Response to Biologics in CRSwNP.

PURPOSE OF REVIEW: Three biologics targeting type 2 inflammation have been approved for the treatment of severe and uncontrolled chronic rhinosinusitis with nasal polyps (CRSwNP). Nevertheless, around 40-60% of patients do not respond well to these biological treatments. Selecting appropriate patients is crucial to improve treatment outcome of biologics. This review summarizes the literature data on type 2 biomarkers, with a specific focus on the indication to biologics for severe CRSwNP. RECENT FINDINGS: No consensus has been reached on how to define mucosal type 2 inflammation in CRSwNP. Clinical markers (e.g., 22-item Sino-nasal Outcome Test (SNOT-22) score, Lund-Mackay CT score (LMS), ethmoid/maxillary sinus CT score, and CT-radiomics), nasal secretion biomarkers (e.g., eosinophil cationic protein and interleukin-5), blood and nasal cytology eosinophil counts, and nasal swab eosinophil peroxidase activity have been reported to be associated with type 2 inflammation in CRSwNP. The time duration since the last surgery, SNOT-22 score at 1 week of treatment, and baseline serum osteoprotegerin levels might indicate the response to dupilumab. LMS and asthma control test scores were found to have moderate predictive value for acceptable improvement after 24-week treatment of omalizumab. High blood eosinophil levels at baseline were associated with treatment response to mepolizumab and benralizumab. Although several clinical and biological markers might be associated with type 2 inflammation and response to biologics in patients with CRSwNP, their validity requires further investigation. Identifying clinically applicable biomarkers for biologic treatment holds significant promise for advancing personalized approaches to biologics and optimizing treatment outcomes for patients with CRSwNP.

Hypoxia-inducible factor 1α activates the NLRP3 inflammasome to regulate epithelial differentiation in chronic rhinosinusitis.

BACKGROUND: Chronic rhinosinusitis (CRS) is an upper airway inflammation disease associated with hypoxia-mediated inflammation. The effect of hypoxia-inducible factor 1α (HIF-1α) on NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation in the pathogenesis of sinonasal mucosa is unclear. OBJECTIVE: We investigated the effect and mechanism of HIF-1α on NLRP3 inflammasome activation in the primary human nasal epithelial cells (hNECs). METHODS: We measured the expression levels of HIF-1α and the NLRP3 inflammasome in nasal biopsy samples and hNECs derived from negative controls (healthy) and patients with CRS with and without nasal polyps, then further analyzed the specific mechanism of HIF-1α regulation of the NLRP3 inflammasome and its effect on hNEC differentiation. RESULTS: Increased mRNA and protein expression levels of HIF-1α and the NLRP3 inflammasome were found in all CRS biopsy samples. HIF-1α enhanced expression of phosphorylated NLRP3 (S295) in both HEK293T cells and hNECs; it also promoted recruitment of caspase-1 and apoptotic speck-like protein containing caspase recruitment domain (aka ASC) by NLRP3. HIF-1α also improved NLRP3's stability by preventing NLRP3 degradation caused by hypoxia-mediated inflammation. In addition, HIF-1α could also increase expression of Mucin5AC and decrease expression of α-tubulin by promoting activation of the NLRP3 inflammasome in hNECs. In addition, HIF-1α could also directly promote P63 expression in hNECs. CONCLUSION: HIF-1α could potentially induce cilia loss and enhance the proliferation of goblet cells, possibly mediated by the regulation of NLRP3 phosphorylation in CRS inflammation.

Mepolizumab in chronic rhinosinusitis with nasal polyposis.

Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a heterogeneous upper airway disease that is prevalent globally. Recent research into the molecular basis of the disease has led to the development of biologics as a new therapeutic option for severe and recalcitrant forms of CRSwNP. Mepolizumab is a monoclonal antibody targeting IL-5, one of the signature cytokines of the type 2 immune response and which plays an important role in the pathogenesis of CRSwNP. Here we present the latest evidence behind mepolizumab, examining disease pathophysiology and pharmacology, as well as data from clinical trials, real-life studies and meta-analyses. As we welcome this promising step forward into precision medicine, we discuss practical issues and future perspectives on mepolizumab and biologics for CRSwNP.

Mepolizumab is a new injectable drug developed to control difficult-to-treat cases of chronic rhinosinusitis with nasal polyposis (CRSwNP), an inflammatory disease of the nose that affects many people worldwide. It works by blocking the action of IL-5, an important protein in the body that regulates inflammation. One of the main effects of this protein is promoting the activity of eosinophils, a type of white blood cell. Eosinophils contribute to tissue damage when activated inappropriately. A recent large-scale study (SYNAPSE) on patients using this drug has been completed, reporting favorable results. In this article, we discuss the science behind the disease, the drug and data from patient studies. We conclude by discussing several future challenges and opportunities in the management of CRSwNP.

Dicoumarol is an effective post-exposure prophylactic for SARS-CoV-2 Omicron infection in human airway epithelium.

Repurposing existing drugs to inhibit SARS-CoV-2 infection in airway epithelial cells (AECs) is a quick way to find novel treatments for COVID-19. Computational screening has found dicoumarol (DCM), a natural anticoagulant, to be a potential SARS-CoV-2 inhibitor, but its inhibitory effects and possible working mechanisms remain unknown. Using air-liquid interface culture of primary human AECs, we demonstrated that DCM has potent antiviral activity against the infection of multiple Omicron variants (including BA.1, BQ.1 and XBB.1). Time-of-addition and drug withdrawal assays revealed that early treatment (continuously incubated after viral absorption) of DCM could markedly inhibit Omicron replication in AECs, but DCM did not affect the absorption, exocytosis and spread of viruses or directly eliminate viruses. Mechanistically, we performed single-cell sequencing analysis (a database of 77,969 cells from different airway locations from 10 healthy volunteers) and immunofluorescence staining, and showed that the expression of NAD(P)H quinone oxidoreductase 1 (NQO1), one of the known DCM targets, was predominantly localised in ciliated AECs. We further found that the NQO1 expression level was positively correlated with both the disease severity of COVID-19 patients and virus copy levels in cultured AECs. In addition, DCM treatment downregulated NQO1 expression and disrupted signalling pathways associated with SARS-CoV-2 disease outcomes (e.g., Endocytosis and COVID-19 signalling pathways) in cultured AECs. Collectively, we demonstrated that DCM is an effective post-exposure prophylactic for SARS-CoV-2 infection in the human AECs, and these findings could help physicians formulate novel treatment strategies for COVID-19.

Predictive Significance of Claudin-3 for Epithelial Barrier Dysfunction in Chronic Rhinosinusitis With Nasal Polyps.

PURPOSE: The abnormal expression of tight junction (TJ) plays a vital role in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP). However, there is no appropriate tool to distinguish and diagnose epithelial barrier defects in clinical practice. This study aimed to evaluate the predictive value of claudin-3 for epithelial barrier dysfunction in CRSwNP. METHODS: In this study, TJ protein levels were evaluated by real-time quantitative polymerase chain reaction, immunofluorescent, and immunohistochemistry staining in control subjects and CRSwNP patients. The receiver operating characteristic (ROC) curve was created to assess the predictive value of TJ breakdown in clinical outcomes. In vitro, human nasal epithelial cells were cultured at the air-liquid interface to analyze the transepithelial electrical resistance (TER) level. RESULTS: The expression levels of occludin, tricellulin, claudin-3, and claudin-10 were decreased (all P < 0.05), and those of claudin-1 was increased (P < 0.05) in CRSwNP patients as compared to healthy subjects. Additionally, claudin-3 and occludin levels were negatively correlated with the computed tomography score in CRSwNP (all P < 0.05), and the ROC curve indicated that the claudin-3 level had the most predictive accuracy in evaluating epithelial barrier disruption (area under the curve = 0.791, P < 0.001). Finally, the time-series analysis showed the highest correlation coefficient between TER and claudin-3 (cross-correlation function = 0.75). CONCLUSION: In this study, we suggest that claudin-3 could be a valuable biomarker for predicting nasal epithelial barrier defects and disease severity in CRSwNP.

Prolonged Primary Rhinovirus Infection of Human Nasal Epithelial Cells Diminishes the Viral Load of Secondary Influenza H3N2 Infection via the Antiviral State Mediated by RIG-I and Interferon-Stimulated Genes.

Our previous study revealed that prolonged human rhinovirus (HRV) infection rapidly induces antiviral interferons (IFNs) and chemokines during the acute stage of infection. It also showed that expression levels of RIG-I and interferon-stimulated genes (ISGs) were sustained in tandem with the persistent expression of HRV RNA and HRV proteins at the late stage of the 14-day infection period. Some studies have explored the protective effects of initial acute HRV infection on secondary influenza A virus (IAV) infection. However, the susceptibility of human nasal epithelial cells (hNECs) to re-infection by the same HRV serotype, and to secondary IAV infection following prolonged primary HRV infection, has not been studied in detail. Therefore, the aim of this study was to investigate the effects and underlying mechanisms of HRV persistence on the susceptibility of hNECs against HRV re-infection and secondary IAV infection. We analyzed the viral replication and innate immune responses of hNECs infected with the same HRV serotype A16 and IAV H3N2 at 14 days after initial HRV-A16 infection. Prolonged primary HRV infection significantly diminished the IAV load of secondary H3N2 infection, but not the HRV load of HRV-A16 re-infection. The reduced IAV load of secondary H3N2 infection may be explained by increased baseline expression levels of RIG-I and ISGs, specifically MX1 and IFITM1, which are induced by prolonged primary HRV infection. As is congruent with this finding, in those cells that received early and multi-dose pre-treatment with Rupintrivir (HRV 3C protease inhibitor) prior to secondary IAV infection, the reduction in IAV load was abolished compared to the group without pre-treatment with Rupintrivir. In conclusion, the antiviral state induced from prolonged primary HRV infection mediated by RIG-I and ISGs (including MX1 and IFITM1) can confer a protective innate immune defense mechanism against secondary influenza infection.

Review on the Advancements of Stethoscope Types in Chest Auscultation.

Stethoscopes were originally designed for the auscultation of a patient's chest for the purpose of listening to lung and heart sounds. These aid medical professionals in their evaluation of the cardiovascular and respiratory systems, as well as in other applications, such as listening to bowel sounds in the gastrointestinal system or assessing for vascular bruits. Listening to internal sounds during chest auscultation aids healthcare professionals in their diagnosis of a patient's illness. We performed an extensive literature review on the currently available stethoscopes specifically for use in chest auscultation. By understanding the specificities of the different stethoscopes available, healthcare professionals can capitalize on their beneficial features, to serve both clinical and educational purposes. Additionally, the ongoing COVID-19 pandemic has also highlighted the unique application of digital stethoscopes for telemedicine. Thus, the advantages and limitations of digital stethoscopes are reviewed. Lastly, to determine the best available stethoscopes in the healthcare industry, this literature review explored various benchmarking methods that can be used to identify areas of improvement for existing stethoscopes, as well as to serve as a standard for the general comparison of stethoscope quality. The potential use of digital stethoscopes for telemedicine amidst ongoing technological advancements in wearable sensors and modern communication facilities such as 5G are also discussed. Based on the ongoing trend in advancements in wearable technology, telemedicine, and smart hospitals, understanding the benefits and limitations of the digital stethoscope is an essential consideration for potential equipment deployment, especially during the height of the current COVID-19 pandemic and, more importantly, for future healthcare crises when human and resource mobility is restricted.

Evaluation of In Vitro and In Vivo Antiviral Activities of Vitamin D for SARS-CoV-2 and Variants.

The COVID-19 pandemic has brought about unprecedented medical and healthcare challenges worldwide. With the continual emergence and spread of new COVID-19 variants, four drug compound libraries were interrogated for their antiviral activities against SARS-CoV-2. Here, we show that the drug screen has resulted in 121 promising anti-SARS-CoV-2 compounds, of which seven were further shortlisted for hit validation: citicoline, pravastatin sodium, tenofovir alafenamide, imatinib mesylate, calcitriol, dexlansoprazole, and prochlorperazine dimaleate. In particular, the active form of vitamin D, calcitriol, exhibits strong potency against SARS-CoV-2 on cell-based assays and is shown to work by modulating the vitamin D receptor pathway to increase antimicrobial peptide cathelicidin expression. However, the weight, survival rate, physiological conditions, histological scoring, and virus titre between SARS-CoV-2 infected K18-hACE2 mice pre-treated or post-treated with calcitriol were negligible, indicating that the differential effects of calcitriol may be due to differences in vitamin D metabolism in mice and warrants future investigation using other animal models.

The respiratory syncytial virus SH protein is incorporated into infectious virus particles that form on virus-infected cells.

The association of the SH protein with respiratory syncytial virus (RSV) particles was examined in HEp2 cells and human ciliated nasal epithelial cells. Imaging of infected cells demonstrated the presence of the SH protein in virus filaments, and analysis of purified RSV particles revealed a SH protein species whose size was consistent with the glycosylated SH protein. Although the SH protein was detected in virus filaments it was not required for virus filament formation. Analysis of RSV-infected ciliated cells also revealed that the SH protein was trafficked into the cilia, and this correlated with reduced cilia density on these cells. Reduced cilia loss was not observed on ciliated cells infected with a RSV isolate that failed to express the SH protein. These data provide direct evidence that the SH protein is trafficked into virus particles, and suggests that the SH protein may also promote cilia dysfunction on nasal epithelial cells.

The Diagnostic and Prognostic Role of Biomarkers in Chronic Rhinosinusitis.

Chronic rhinosinusitis (CRS) refers to an inflammatory disease of the sinonasal mucosa, with a significant economic burden and impact on quality of life. The diagnosis of CRS is conventionally made on careful history and physical examination, including nasoendoscopic assessment which requires technical expertise. There has been increasing interest in using biomarkers in the non-invasive diagnosis and prognostication of CRS, tailored to the disease inflammatory endotype. Potential biomarkers currently being studied can be isolated from peripheral blood, exhaled nasal gases or nasal secretions, as well as sinonasal tissue. In particular, various biomarkers have revolutionized the way in which CRS is managed, revealing new inflammatory pathways where novel therapeutic drugs are employed to curb the inflammatory process, which may be different from one patient to the next. Biomarkers that have been extensively studied in CRS, such as eosinophil count, IgE, and IL-5, have been associated with a TH2 inflammatory endotype which correlates with an eosinophilic CRSwNP phenotype that predicts a poorer prognosis, tends to recur after conventional surgical treatment, but responds to glucocorticoid treatment. Newer biomarkers that demonstrate potential, such as nasal nitric oxide, can support a diagnosis of CRS with or without nasal polyps, especially when invasive tests such as nasoendoscopy are unavailable. Other biomarkers such as periostin can be used to monitor disease course after treatment of CRS. With a personalized treatment plan, the management of CRS can be individualized, optimizing treatment efficiency and reducing adverse outcomes. As such, this review aims to compile and summarize the existing literature regarding the utility of biomarkers in CRS in terms of diagnosis and prognostication, and also makes recommendations for further studies to fill current knowledge gaps.

Pathophysiology of SARS-CoV-2 Infection of Nasal Respiratory and Olfactory Epithelia and Its Clinical Impact.

PURPOSE OF REVIEW: While the predominant cause for morbidity and mortality with SARS-CoV-2 infection is the lower respiratory tract manifestations of the disease, the effects of SARS-CoV-2 infection on the sinonasal tract have also come to the forefront especially with the increased recognition of olfactory symptom. This review presents a comprehensive summary of the mechanisms of action of the SARS-CoV-2 virus, sinonasal pathophysiology of COVID-19, and the correlation with the clinical and epidemiological impact on olfactory dysfunction. RECENT FINDINGS: ACE2 and TMPRSS2 receptors are key players in the mechanism of infection of SARS-CoV-2. They are present within both the nasal respiratory as well as olfactory epithelia. There are however differences in susceptibility between different groups of individuals, as well as between the different SARS-CoV-2 variants. The sinonasal cavity is an important route for SARS-CoV-2 infection. While the mechanism of infection of SARS-CoV-2 in nasal respiratory and olfactory epithelia is similar, there exist small but significant differences in the susceptibility of these epithelia and consequently clinical manifestations of the disease. Understanding the differences and nuances in sinonasal pathophysiology in COVID-19 would allow the clinician to predict and counsel patients suffering from COVID-19. Future research into molecular pathways and cytokine responses at different stages of infection and different variants of SARS-CoV-2 would evaluate the individual clinical phenotype, prognosis, and possibly response to vaccines and therapeutics.

Generation of self-replicating airway organoids from the cave nectar bat Eonycteris spelaea as a model system for studying host-pathogen interactions in the bat airway epithelium.

Bats are reservoir hosts for various zoonotic viruses with pandemdic potential in humans and livestock. In vitro systems for studying bat host-pathogen interactions are of significant interest. Here, we establish protocols to generate bat airway organoids (AOs) and airway epithelial cells differentiated at the air-liquid interface (ALI-AECs) from tracheal tissues of the cave-nectar bat Eonycteris spelaea. In particular, we describe steps which enable laboratories that do not have access to live bats to perform extended experimental work upon procuring an initial batch of bat primary airway tissue. Complete mucociliary differentiation required treatment with IL-13. E. spelaea ALI-AECs supported productive infection with PRV3M, an orthoreovirus for which Pteropodid bats are considered the reservoir species. However, these ALI-AECs did not support SARS-CoV-2 infection, despite E. spelaea ACE2 receptor being capable of mediating SARS-CoV-2 spike pseudovirus entry. This work provides critical model systems for assessing bat species-specific virus susceptibility and the reservoir likelihood for emerging infectious agents.